CN107936501B - Injection molded article and method of making the same - Google Patents

Injection molded article and method of making the same Download PDF

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CN107936501B
CN107936501B CN201610892111.7A CN201610892111A CN107936501B CN 107936501 B CN107936501 B CN 107936501B CN 201610892111 A CN201610892111 A CN 201610892111A CN 107936501 B CN107936501 B CN 107936501B
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blend
poly
thermoplastic cellulose
cellulose
injection molding
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CN107936501A (en
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詹姆斯·洪学·王
周炳
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
    • C08F251/02—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof on to cellulose or derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
    • C08L51/02—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to polysaccharides

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  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Abstract

The invention relates to a blend injection molding product of thermoplastic cellulose, microbial synthetic polyester and reactive monomer, which mainly solves the technical problems of high viscosity and poor injection molding processability of the thermoplastic cellulose in the low-temperature processing process and limited application field in the prior art. The invention adopts an injection molding product, contains a grafted modified thermoplastic cellulose and microbial synthetic polyester blend, and the grafted modified thermoplastic cellulose and microbial synthetic polyester blend comprises the following components in parts by mass: 1)20 to 80 parts of thermoplastic cellulose; 2)80 to 20 parts of a microbiologically synthesized polyester; 3)0.1 to 10 parts of a reactive monomer; the technical proposal that the reactive monomer in the blend is grafted at least to one of the thermoplastic cellulose and the microbial synthetic polyester better solves the problem and can be used in the industrial production of biodegradable injection molding products.

Description

Injection molded article and method of making the same
Technical Field
The invention belongs to the field of injection molding products, particularly relates to a blend injection molding product of graft modified thermoplastic cellulose and microbial synthetic polyester with special rheological properties, and also relates to a method for preparing the blend injection molding product of the graft modified thermoplastic cellulose and the microbial synthetic polyester with the special rheological properties.
Technical Field
Cellulose is the most abundant organic polymer on earth and also the most renewable biomass material every year. Cellulose is the structural material in the cell wall of green plants, woody plants contain about 30-40% cellulose, and cotton fibers contain about 90% cellulose. The main industrial uses of cellulose are paper and board, with a small amount of cellulose being used for the preparation of regenerated cellulose such as cellulophenol (Cellophane), viscose (Rayon) and some cellulose derivatives.
Since cellulose is a natural polymer that plants convert carbon dioxide and water in the atmosphere into carbon dioxide and water through photosynthesis, carbon elements in cellulose belong to recently fixed carbon and are different from carbon elements fixed millions of years ago in fossil fuels such as petroleum or coal and petrochemical products thereof, and carbon elements fixed at different periods can pass through14And C isotope calibration method. Due to the fact thatBased on the differences, the bio-based polymer product prepared from the biomass raw material has the advantage of low carbon of the raw material compared with the petroleum-based polymer product, and the green low-carbon polymer product can be produced by adopting the production process with low energy consumption and low carbon emission. In view of such considerations, natural polymers, including cellulose, hemicellulose, lignin, starch, chitin, etc., and derivatives thereof, are receiving increasing attention and research and development in the world to develop high-quality green, low-carbon, and environmentally-friendly products. The wide application of the green low-carbon products confirmed by Life Cycle Assessment (Life Cycle Assessment) is helpful for supporting green production and green Life style, and contributes to reducing the content of greenhouse effect gases (carbon dioxide and the like) in the atmosphere and relieving global climate change.
Although cellulose has the advantage of low carbon in raw materials, the amount of cellulose used as plastic injection molded articles is small because cellulose does not have thermoplastic properties due to its thermal decomposition temperature below its melting point. In order to overcome the defect of cellulose, researchers have developed regenerated cellulose produced by a solution method, i.e. cellulose or a cellulose derivative is dissolved in a solvent, and is processed and formed by the solution to be prepared into a film or is converted into cellulose after spinning, and viscose in the textile industry is prepared by the method.
In addition, the cellulose derivative has a low melting or plasticizing temperature after sufficient chemical transformation of the three hydroxyl groups of each repeated anhydroglucose unit, can be subjected to limited thermoplastic processing to form thermoplastic cellulose, and the materials comprise cellulose ester and cellulose ether with a certain degree of substitution. Because the yield and the product variety of the cellulose derivatives are limited, the viscosity of the industrialized products is higher, and is particularly obvious at lower processing temperature, and the products are not suitable for processing methods needing low melt viscosity, such as spinning, injection molding and the like; cellulose esters and cellulose ethers are currently used in large part as additives in the field of coatings or adhesives [ gayal, manoming, biomass materials and applications, 2008 ]. Therefore, from the viewpoint of processing applications, there is a technical need to develop a thermoplastic cellulose derivative having a low viscosity and good processability to meet the market demand of the relevant raw materials.
To date, no document has reported the particular rheological behavior of graft-modified thermoplastic cellulose and microbial synthetic polyester blends, and no method has been provided in the prior art to effectively reduce the melt viscosity of thermoplastic cellulose and microbial synthetic polyester blends, limiting the utility of such blends.
The invention discloses a continuous melt extrusion method for effectively reducing the melt viscosity of a blend of thermoplastic cellulose and microbial synthetic polyester, discovers unexpected phenomena and results, discloses a blend composition with special rheological properties, and successfully applies the blend to the field of injection molding products.
Disclosure of Invention
One of the technical problems solved by the invention is that the melt viscosity of the thermoplastic cellulose and microorganism synthetic polyester blend in the prior art is too high to be applied to injection molding products prepared by low melt viscosity, and provides a graft modified thermoplastic cellulose and microorganism synthetic polyester blend injection molding product with special rheological property, and the blend material adopted by the injection molding product can effectively reduce the viscosity of the blend to be lower than the theoretical viscosity of the blend addition of the thermoplastic cellulose and microorganism synthetic polyester starting materials; the blend has the processing performance of making injection molding products at lower temperature, is superior to the similar blend in the prior art, and can save more energy in the processing process due to low melt viscosity of the blend.
The second technical problem to be solved by the present invention is to provide a process for preparing an injection molded article of a graft-modified thermoplastic cellulose and microbial synthetic polyester blend having specific rheological properties, the melt viscosity of the blend obtained by the process being at a low shear rate (100 s)-1) At least about 50% lower than the theoretical value of the additive blend of the two starting materials under the conditions; at high shear rate (1363 s)-1) Under the condition, the additive ratio is at least 45 percent lower than the blending additive theoretical value of the two starting materials.
In order to solve one of the above technical problems, the technical scheme adopted by the invention is as follows: an injection molding product contains a blend of graft modified thermoplastic cellulose and microbial synthetic polyester, and the blend of the graft modified thermoplastic cellulose and the microbial synthetic polyester comprises the following components in parts by mass:
(1)20 to 80 parts of thermoplastic cellulose;
(2)80 to 20 parts of a microbiologically synthesized polyester;
(3)0.1 to 10 parts of a reactive monomer;
wherein the reactive monomer in the blend is grafted onto at least one of the thermoplastic cellulose and the microbial synthetic polyester.
In the above technical solution, the injection molded article is prepared from the graft-modified thermoplastic cellulose and microbial synthetic polyester blend, wherein the graft-modified thermoplastic cellulose and microbial synthetic polyester blend has special rheological properties, for example, but not limited to, preferably the melt viscosity of the blend is 100s at low shear rate-1Under the condition, the additive ratio is at least 50 percent lower than the blending additive theoretical value of the two main starting materials; at high shear rate 1363s-1At least 45% lower than the blended addition theoretical starting material of the two main starting materials.
In the above technical scheme, the two main starting materials refer to thermoplastic cellulose and microbial synthetic polyester
In the above technical solution, the substitution degree of the thermoplastic cellulose is preferably greater than 1.0; more suitable cellulose derivatives have a degree of substitution of more than 1.5, particularly suitable cellulose derivatives have a degree of substitution of more than 2.0.
In the above-mentioned embodiment, the thermoplastic cellulose is preferably cellulose acetate butyrate ester, cellulose acetate valerate ester, cellulose acetate caproate ester, cellulose acetate enanthate ester, cellulose acetate caprylate ester, cellulose acetate pelargonate ester, cellulose acetate caprate ester, cellulose acetate laurate ester, cellulose acetate palmitate ester, cellulose acetate stearate ester, cellulose propionate butyrate ester, cellulose propionate valerate ester, cellulose propionate caproate ester, cellulose propionate enanthate ester, cellulose propionate caprylate ester, cellulose propionate pelargonate ester, cellulose propionate caprate ester, cellulose propionate laurate ester, cellulose propionate stearate ester, or the like.
In the technical scheme, the microbial synthetic polyester is a polyester which is prepared by a microbial fermentation method and can be completely biodegraded and completely bio-based.
In the above technical solution, the microbial synthetic polyester is preferably: poly 3-hydroxybutyrate (PHB), poly 3-hydroxyvalerate (PHV), poly 3-hydroxyhexanoate (PHH), poly 3-hydroxyheptanoate, poly 3-hydroxyoctanoate, poly 3-hydroxynonanoate, poly 3-hydroxydecanoate, poly 3-hydroxylaurate, poly 3-hydroxypalmitate, poly 3-hydroxystearate and other microbial synthetic homopolyesters as well as poly 3-hydroxybutyrate-3-hydroxyvalerate (PHBV, P3HB3HV), poly 3-hydroxybutyrate-4 hydroxybutyrate (P3HB4HB), poly 3-hydroxybutyrate-3-hydroxyhexanoate (PHBHHx or 3HBHx), poly 3-hydroxybutyrate-3-hydroxyheptanoate, poly 3-hydroxybutyrate-3-hydroxyoctanoate, poly-3-hydroxybutyrate-3-hydroxynonanoate, poly-3-hydroxybutyrate-3-hydroxydecanoate, poly-3-hydroxybutyrate-3-hydroxylaurate, poly-3-hydroxybutyrate-3-hydroxypalmitate, poly-3-hydroxybutyrate-3-hydroxystearate; poly 3-hydroxypentanoic acid-3-hydroxyhexanoate, poly 3-hydroxypentanoic acid-3-hydroxyheptanoate, poly 3-hydroxypentanoic acid-3-hydroxyoctanoate, poly 3-hydroxypentanoic acid-3-hydroxynonanoate, poly 3-hydroxypentanoic acid-3-hydroxydecanoate, poly 3-hydroxypentanoic acid-3-hydroxylaurate, poly 3-hydroxypentanoic acid-3-hydroxypalmitate, poly 3-hydroxypentanoic acid-3-hydroxystearate; poly 3-hydroxyhexanoate-3-hydroxyheptanoate, poly 3-hydroxyhexanoate-3-hydroxyoctanoate, poly 3-hydroxyhexanoate-3-hydroxynonanoate, poly 3-hydroxyhexanoate-3-hydroxydecanoate, poly 3-hydroxyhexanoate-3-hydroxylaurate, poly 3-hydroxyhexanoate-3-hydroxypalmitate, poly 3-hydroxyhexanoate-3-hydroxystearate; poly-3-hydroxyheptanoate-3-hydroxyoctanoate, poly-3-hydroxyheptanoate-3-hydroxynonanoate, poly-3-hydroxyheptanoate-3-hydroxydecanoate, poly-3-hydroxyheptanoate-3-hydroxylaurate, poly-3-hydroxyheptanoate-3-hydroxypalmitate, 3-hydroxyheptanoate-3-hydroxystearate; poly 3-hydroxyoctanoic acid-3-hydroxynonanoate, poly 3-hydroxyoctanoic acid-3-hydroxydecanoate, poly 3-hydroxyoctanoic acid-3-hydroxylaurate, poly 3-hydroxyoctanoic acid-3-hydroxypalmitate, poly 3-hydroxyoctanoic acid-3-hydroxystearate; poly-3-hydroxynonanoate-3-hydroxydecanoate, poly-3-hydroxynonanoate-3-hydroxylaurate, poly-3-hydroxynonanoate-3-hydroxypalmitate, poly-3-hydroxynonanoate-3-hydroxystearate; at least one of copolyester synthesized by microorganisms such as poly 3-hydroxydecanoic acid-3-hydroxylaurate, poly 3-hydroxydecanoic acid-3-hydroxy palmitate and poly 3-hydroxydecanoic acid-3-hydroxystearate.
In the above technical solution, the microorganism-synthesized polyester is more preferably: at least one of poly 3-hydroxybutyrate, poly 3-hydroxybutyrate-3-hydroxyvalerate, poly 3-hydroxybutyrate-4-hydroxybutyrate, poly 3-hydroxybutyrate-3-hydroxyhexanoate, poly 3-hydroxybutyrate-3-hydroxyoctanoate, poly 3-hydroxybutyrate-3-hydroxynonanoate, poly 3-hydroxybutyrate-3-hydroxydecanoate, poly 3-hydroxybutyrate-3-hydroxylaurate, poly 3-hydroxybutyrate-3-hydroxypalmitate, poly 3-hydroxybutyrate-3-hydroxystearate and the like.
In the above embodiment, the melt index of the blend is at least about 90% higher than the theoretical value of the blend addition of the two main starting materials.
In the above technical scheme, the reactive monomer is at least one of compounds having polar groups such as hydroxyl, carboxyl, carbonyl, ester, amino, mercapto, sulfonic acid, ether bond, halogen, peptide bond, and acid anhydride bond, and further containing unsaturated carbon-carbon double bond. The reactive monomer can react with other components in the blend under certain conditions, and then is grafted to other components through covalent bonds, so that a special modification effect is achieved.
In the above technical solution, the reactive monomer is preferably at least one of maleic anhydride, acrylic acid, methacrylic acid, acrylate, methacrylate, acrylamide, methacrylamide and the like.
In the above technical solution, the blend preferably further comprises: 0.01 to 1 part by mass of an initiator.
In the above technical solution, the initiator is a radical initiator, and is an organic compound that can be decomposed under certain conditions to generate radicals, including but not limited to: acyl peroxides, such as Benzoyl Peroxide (BPO); alkyl (dialkyl) peroxides such as di-t-butylperoxide, di-cumylperoxide, cumylperoxide butyl, 3, 5-trimethylcyclohexane-1, 1-diperoxy-t-butyl, 2, 5-dimethyl-2, 5-di-t-butylperoxyhexane, and the like; peresters such as t-butyl peroxypivalate, t-butyl per-2-ethylhexanoate, t-butyl perbenzoate, peroxydodecanoic acid, etc.; alkyl hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, etc.; ketone peroxides, such as methyl ethyl ketone peroxide; azo compounds, such as Azobisisobutyronitrile (AIBN).
In the above technical solution, the initiator is preferably at least one of benzoyl peroxide, azobisisobutyronitrile, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoic acid peroxide, 2, 5-dimethyl-2, 5-di-tert-butyl peroxy hexane, and the like.
In the above technical solution, the thermoplastic cellulose is preferably cellulose acetate butyrate ester, the microbial synthetic polyester is preferably poly-3-hydroxybutyrate, poly-3-hydroxybutyrate-3-hydroxyvalerate, poly-3-hydroxybutyrate-3-hydroxyhexanoate, etc., the reactive monomer is preferably hydroxyethyl methacrylate, glycidyl methacrylate, etc., and the initiator is preferably benzoyl peroxide, 2, 5-dimethyl-2, 5-di-tert-butyl hexane peroxide (bis-penta), etc., at this time, the mixture components have good compatibility, and the mixture shows special rheological properties, which can greatly widen the application range of the starting material, and the lower melt viscosity can reduce the energy consumption in the material processing process.
In the above technical solution, the blend material most preferably contains 20 to 80 parts by mass of thermoplastic cellulose, 80 to 20 parts by mass of the microbial synthetic polyester, 0.1 to 10 parts by mass of the reactive monomer and 0.01 to 1 part by mass of the initiator, at this time, the synergistic interaction between the components is most obvious, and the rheological property and compatibility of the obtained blend are both optimal.
In the above technical solution, the blend material preferably further contains at least one of a compatibilizer, an inorganic filler, an antioxidant, a lubricant, a colorant, and the like.
In the above technical scheme, the melt viscosity of the blend injection-molded product is preferably at low shear rate (100 s)-1) Under the conditions of at least 65% lower (preferably 50 to 20 parts by mass of the microbiologically synthesized polyester and 50 to 80 parts by mass of the thermoplastic cellulose, 2 to 8 parts by mass of the reactive monomer, and 0.05 to 0.2 parts by mass of the initiator), and further preferably at least 70% lower (more preferably 35 parts by mass of the microbiologically synthesized polyester and 65 parts by mass of the thermoplastic cellulose, 2 to 6 parts by mass of the reactive monomer, and 0.075 to 0.15 parts by mass of the initiator) than the blending addition theoretical value of the two main starting materials.
In the above technical solution, the melt viscosity of the blend injection molded article is preferably at a high shear rate (1363 s)-1) Under conditions of at least 60% lower than the blending addition theoretical value of the two main starting materials (preferably 50 to 20 parts by mass of the microbial synthetic polyester and 50 to 80 parts by mass of the thermoplastic cellulose, 2 to 8 parts by mass of the reactive monomer, and 0.05 to 0.2 part by mass of the initiator), and further preferably at least 65% lower (more preferably 35 parts by mass of the microbial synthetic polyester and 65 parts by mass of the thermoplastic cellulose, 2 to 6 parts by mass of the reactive monomer, and 0.075 to 0.15 parts by mass of the initiator).
In the above-mentioned embodiment, the melt index of the injection-molded article of the blend is preferably at least about 90% higher, more preferably at least about 200% higher than the theoretical value of the blend addition of the two main starting materials (preferably 50 to 20 parts by mass of the microbial synthetic polyester and 50 to 80 parts by mass of the thermoplastic cellulose, the reactive monomer is 2 to 8 parts by mass, and the initiator is 0.05 to 0.2 parts by mass), and more preferably at least about 300% higher (more preferably 35 parts by mass of the microbial synthetic polyester and 65 parts by mass of the thermoplastic cellulose, the reactive monomer is 2 to 6 parts by mass, and the initiator is 0.075 to 0.15 parts by mass).
In the technical scheme, the microbial synthetic polyester (polyhydroxyalkanoate) comprises short-side-chain polyhydroxyalkanoate and medium-side-chain polyhydroxyalkanoate. Short-side polyhydroxyalkanoates include polyhydroxyalkanoates containing 4 and 5 carbon units such as poly-3-hydroxybutyrate, 3-hydroxybutyrate-3-hydroxyvalerate, which can be synthesized by a variety of bacteria including ralstonia eutropha, Alcaligenes latices. The crystallinity of the polyhydroxyalkanoates is higher, such as the crystallinity of poly 3-hydroxybutyrate (PHB) can reach 70 percent, the melting point is high (about 180 ℃) and is close to the decomposition temperature of the PHB, and the polyhydroxyalkanoates are not easy to be subjected to thermoplastic processing; PHB has high modulus (3.5 GPa can be achieved), high strength (>40MPa), but the elongation at break of the material (about 5%) is low. 3-hydroxybutyrate-3-hydroxyvalerate (PHBV) has a crystallinity (about 60%) slightly lower than that of PHB, a lower melting point than that of PHB, and a lower melting point as the hydroxyvalerate content in PHBV increases. The thermoplastic processing temperature window of PHBV is wider than that of PHB, but the crystallization speed of PHBV is slower and can reach several minutes or longer, and the thermoplastic processing is difficult.
The medium side chain polyhydroxyalkanoate includes polyhydroxyalkanoate having 6 and 14 carbon units such as poly-3-hydroxybutyric acid-3-hydroxyhexanoate, poly-3-hydroxybutyric acid-3-hydroxyoctanoate, poly-3-hydroxybutyric acid-3-hydroxynonanoate, poly-3-hydroxybutyric acid-3-hydroxydecanoate, poly-3-hydroxybutyric acid-3-hydroxylaurate and the like, which can be synthesized by Pseudomonas putida and the like. The polyhydroxy fatty acid ester has low melting point, obviously improved ductility along with the increase of the number and the content of the carbon atoms of the side chain units, and even has ductility and recoverable deformation similar to an elastomer in some cases. Of these, poly-3-hydroxybutyrate-3-hydroxyhexanoate is particularly useful in the present invention.
In order to solve the second technical problem, the technical scheme adopted by the invention is as follows: a method for preparing the grafted modified thermoplastic cellulose with special rheological property and the microbial synthetic polyester blend injection molding product adopts melt blending, the required amount of components are uniformly mixed in a molten state, the blend melt is cooled and granulated, the blend particles are injected into a mold cavity by an injection screw after being melted and plasticized on an injection molding machine, and the blend melt is separated from an injection mold to form the injection molding product after being cooled in the mold cavity under certain pressure and dwell time.
In the above-mentioned embodiment, the required amounts of the respective components include the required amount of the thermoplastic cellulose, the required amount of the microbial synthetic polyester, the required amount of the reactive monomer, and further preferably the required amount of the initiator.
In the above technical scheme, the melt blending method of the graft modified thermoplastic cellulose and microbial synthetic polyester blend is preferably a twin-screw continuous extrusion method.
In the above technical scheme, the melt blending method of the graft modified thermoplastic cellulose and the microbial synthetic polyester blend preferably comprises the steps of continuously extruding and granulating the thermoplastic cellulose powder, blending the thermoplastic cellulose powder with the microbial synthetic polyester, the reactive monomer and the initiator according to a required ratio, and then adding the mixture to a twin-screw extruder for extrusion and granulation.
In the above technical scheme, the melt blending method of the graft modified thermoplastic cellulose and the microbial synthetic polyester blend preferably comprises the steps of continuously extruding and granulating the thermoplastic cellulose powder, and then respectively metering and adding the thermoplastic cellulose powder, the microbial synthetic polyester, the reactive monomer and the initiator into a double screw extruder according to the required feeding proportion for extrusion and granulation.
In the above technical scheme, the melt blending method of the graft modified thermoplastic cellulose and microbial synthetic polyester blend preferably comprises the steps of respectively metering the thermoplastic cellulose powder, the microbial synthetic polyester, the reactive monomer and the initiator according to a certain feeding proportion, and extruding and granulating the mixture on a twin-screw extruder.
In the above technical scheme, the screw rotation speed of the melt blending method of the graft modified thermoplastic cellulose and the microbial synthetic polyester blend is preferably 50rpm to 1500rpm.
In the above technical solution, the temperature of the melt blending method of the graft-modified thermoplastic cellulose and the microbial synthetic polyester blend is preferably 140 ℃ to 240 ℃.
In order to solve the second technical problem, another method for preparing the injection molded article of the graft modified thermoplastic cellulose and microbial synthetic polyester blend with special rheological properties according to any one of the above technical solutions can be selected: adding the core layer material or the blend into a double-material common injection molding machine, plasticizing and melting the mixture, injecting the mixture into a mold cavity by an injection screw, maintaining pressure and cooling the mixture, separating the mixture from an injection mold to form a core layer of an injection molded product, adding the surface layer material or the blend into another injection molding machine, injecting the mixture into a second mold cavity filled with the core layer, maintaining pressure and cooling the mixture to form a surface layer, and preparing the double-layer injection molded product; wherein, at least one layer of the double-layer injection molding product is the blend of the grafted modified thermoplastic cellulose and the microbial synthetic polyester, and when the two layers are the blend of the grafted modified thermoplastic cellulose and the microbial synthetic polyester, the blend of the grafted modified thermoplastic cellulose and the microbial synthetic polyester in the two layers has different composition ratios of the thermoplastic cellulose, the microbial synthetic polyester, the reactive monomer and the initiator.
In the above technical solution, the thickness of the core layer of the double-layer injection molding product accounts for 95 to 55% of the total thickness (including the core layer and the skin layer) of the double-layer injection molding product.
In the technical scheme, the surface layer part and the core part of the double-layer injection molding product have different physical properties, chemical properties, mechanical properties and the like, for example, the surface layer part has higher toughness than the core part, so that the injection molding product is not easy to damage under the action of external stress and impact force; or the surface layer portion has a higher degree of wear resistance than the core portion, and the injection molded article is less likely to be damaged by external mechanical wear, etc.
In the above technical scheme, the core layer material and the surface layer material are completely different materials from the blend of the present invention, such as low density polyethylene, linear low density polyethylene, high density polyethylene, polypropylene, polyolefin elastomer, ethylene propylene rubber, polyethylene terephthalate, polyamide, polyurethane, etc.
The materials and preparation methods used in the present invention are briefly described below:
1. thermoplastic cellulose
The thermoplastic cellulose is a cellulose derivative with a wide range, and the three hydroxyl groups on each repeated anhydroglucose unit of the cellulose derivative are partially or completely chemically modified in the forms of esterification, etherification, etc. The parameter characterizing its Degree of modification is the Degree of Substitution (Degree of Substitution), which is defined as the average number of substitutions in the three hydroxyl groups per repeating anhydroglucose unit, with a maximum of 3.0(3 hydroxyl groups are completely substituted) and a minimum of 0 (pure cellulose).
The thermoplastic cellulose ester included in the present invention includes a mixed cellulose ester of cellulose and two or more kinds of organic aliphatic carboxylic acid, organic aliphatic acid anhydride and organic aliphatic acid halide, and the difference in the number of carbon atoms between different organic aliphatic carboxylic acid, organic aliphatic acid anhydride and organic aliphatic acid halide is 1 or more.
Cellulose esters are typically made by reacting natural cellulose with an organic acid, anhydride or acid chloride, etc., with a degree of substitution of the hydroxyl groups in the cellulose of from 0.5 to 2.8. Suitable cellulose ester products include Eastman, produced by Eastman chemical company, USATMCellulose acetate butyrate CAB-171-15, CAB-321-0.1, CAB-381-0.1, CAB-381-0.5, CAB-381-20, CAB-485-10, CAB-500-5, CAB-531-1 and the like. For example: CAB-531-1 contains butyryl component 50 wt%, acetyl component 2.8 wt%, and hydroxyl component 1.7 wt%, and has a viscosity of 5.6 poise measured according to ASTM 1343. Cellulose ester is used in fiber, textile, paint, food additive, pharmaceutical industry and other industries. In the coating industry, the addition of cellulose esters can improve the coating effect, including: hardness, flow, flatness, transparency, gloss, and the like. Cellulose Acetate Propionate (CAP) and Cellulose Acetate Butyrate (CAB) are two types of mixed cellulose esters that have a wide range of commercial uses.
2. Microbial synthetic polyester
The microbial synthetic polyester of the invention is a polyester which is prepared by a microbial fermentation method and can be completely biodegraded and completely bio-based. The biopolyester comprises a homopolymer (homo), i.e., a polyester formed from a hydroxy fatty acid ester including poly 3-hydroxybutyrate (PHB), poly 3-hydroxyvalerate (PHV), poly 3-hydroxyhexanoate (PHH), poly 3-hydroxyheptanoate, poly 3-hydroxyoctanoate, poly 3-hydroxynonanoate, poly 3-hydroxydecanoate, poly 3-hydroxylauranate, poly 3-hydroxypalmitate, poly 3-hydroxystearate, and the like.
Suitable microbiologically synthesized polyesters for the present invention include copolyesters formed from two or more hydroxy fatty acid esters including poly 3-hydroxybutyrate-3-hydroxyvalerate (PHBV, P3HB3HV), poly 3-hydroxybutyrate-4 hydroxybutyrate (P3HB4HB), poly 3-hydroxybutyrate-3-hydroxyhexanoate (PHBHx or 3HBHx), poly 3-hydroxybutyrate-3-hydroxyheptanoate, poly 3-hydroxybutyrate-3-hydroxyoctanoate, poly 3-hydroxybutyrate-3-hydroxynonanoate, poly 3-hydroxybutyrate-3-hydroxydecanoate, poly 3-hydroxybutyrate-3-hydroxylaurate, poly 3-hydroxybutyrate-3-hydroxypalmitate, poly 3-hydroxybutyrate-3-hydroxystearate; poly 3-hydroxypentanoic acid-3-hydroxyhexanoate, poly 3-hydroxypentanoic acid-3-hydroxyheptanoate, poly 3-hydroxypentanoic acid-3-hydroxyoctanoate, poly 3-hydroxypentanoic acid-3-hydroxynonanoate, poly 3-hydroxypentanoic acid-3-hydroxydecanoate, poly 3-hydroxypentanoic acid-3-hydroxylaurate, poly 3-hydroxypentanoic acid-3-hydroxypalmitate, poly 3-hydroxypentanoic acid-3-hydroxystearate; poly 3-hydroxyhexanoate-3-hydroxyheptanoate, poly 3-hydroxyhexanoate-3-hydroxyoctanoate, poly 3-hydroxyhexanoate-3-hydroxynonanoate, poly 3-hydroxyhexanoate-3-hydroxydecanoate, poly 3-hydroxyhexanoate-3-hydroxylaurate, poly 3-hydroxyhexanoate-3-hydroxypalmitate, poly 3-hydroxyhexanoate-3-hydroxystearate; poly-3-hydroxyheptanoate-3-hydroxyoctanoate, poly-3-hydroxyheptanoate-3-hydroxynonanoate, poly-3-hydroxyheptanoate-3-hydroxydecanoate, poly-3-hydroxyheptanoate-3-hydroxylaurate, poly-3-hydroxyheptanoate-3-hydroxypalmitate, 3-hydroxyheptanoate-3-hydroxystearate; poly 3-hydroxyoctanoic acid-3-hydroxynonanoate, poly 3-hydroxyoctanoic acid-3-hydroxydecanoate, poly 3-hydroxyoctanoic acid-3-hydroxylaurate, poly 3-hydroxyoctanoic acid-3-hydroxypalmitate, poly 3-hydroxyoctanoic acid-3-hydroxystearate; poly-3-hydroxynonanoate-3-hydroxydecanoate, poly-3-hydroxynonanoate-3-hydroxylaurate, poly-3-hydroxynonanoate-3-hydroxypalmitate, poly-3-hydroxynonanoate-3-hydroxystearate; poly 3-hydroxydecanoic acid-3-hydroxylaurate, poly 3-hydroxydecanoic acid-3-hydroxystearate, and the like.
The microbiologically synthesized polyesters particularly suitable for the present invention include poly-3-hydroxybutyrate, 3-hydroxybutyrate-3-hydroxyvalerate, poly-3-hydroxybutyrate-4-hydroxybutyrate, poly-3-hydroxybutyrate-3-hydroxyhexanoate, poly-3-hydroxybutyrate-3-hydroxyoctanoate, poly-3-hydroxybutyrate-3-hydroxynonanoate, poly-3-hydroxybutyrate-3-hydroxydecanoate, poly-3-hydroxybutyrate-3-hydroxylaurate, poly-3-hydroxybutyrate-3-hydroxypalmitate, poly-3-hydroxybutyrate-3-hydroxystearate and the like.
The microorganism-synthesized polyester of the present invention can be produced by a biological fermentation method using bacteria, yeast, etc., and carbon sources which can be used include various kinds of sugar compounds or lipid substances such as glucose, sucrose, fructose, soybean oil, rapeseed oil, etc. When the microorganisms in the culture broth (e.g., Alcaligenes eutrophus, etc.) multiply to the desired number through cell division, the nitrogen and phosphorus contents of the nutrient broth can then be controlled to inhibit the propagation process, and the bacteria begin to store carbon in a manner that the bacteria have synthesized Polyhydroxyalkanoates (PHAs) under conditions of limited nitrogen and phosphorus in nutrition. After a certain period of time, a higher concentration, such as 10-400 g/l, can be achieved in the fermentation broth, the weight in the dried bacterial cells can be 80% or more, and then Polyhydroxyalkanoate (PHA) is separated from the cells by methods such as cell wall disruption (e.g., using surfactants), solvent extraction, and the like.
The polyhydroxyalkanoate can be prepared from a natural microorganism or a genetically recombinant microorganism. The classes of microorganisms include bacteria, yeast, and the like. Polyhydroxyalkanoates also can be synthesized from transgenic plants containing PHA synthase, including corn, tobacco, switchgrass (switchgrass), and harvested transgenic plants are subjected to solvent extraction to collect polyhydroxyalkanoates.
The polyhydroxyalkanoate includes short-side chain polyhydroxyalkanoate and medium-side chain polyhydroxyalkanoate. Short-side polyhydroxyalkanoates include polyhydroxyalkanoates containing 4 and 5 carbon units such as poly-3-hydroxybutyrate, 3-hydroxybutyrate-3-hydroxyvalerate, which can be synthesized by a variety of bacteria including ralstonia eutropha, Alcaligenes latices. The crystallinity of the polyhydroxyalkanoates is higher, such as the crystallinity of poly 3-hydroxybutyrate (PHB) can reach 70 percent, the melting point is high (about 180 ℃) and is close to the decomposition temperature of the PHB, and the polyhydroxyalkanoates are not easy to be subjected to thermoplastic processing; PHB has high modulus (3.5 GPa can be achieved), high strength (>40MPa), but the elongation at break of the material (about 5%) is low. 3-hydroxybutyrate-3-hydroxyvalerate (PHBV) has a crystallinity (about 60%) slightly lower than that of PHB, a lower melting point than that of PHB, and a lower melting point as the hydroxyvalerate content in PHBV increases. The thermoplastic processing temperature window of PHBV is wider than that of PHB, but the crystallization speed of PHBV is slower and can reach several minutes or longer, and the thermoplastic processing is difficult.
The medium side chain polyhydroxyalkanoate includes polyhydroxyalkanoate having 6 and 14 carbon units such as poly-3-hydroxybutyric acid-3-hydroxyhexanoate, poly-3-hydroxybutyric acid-3-hydroxyoctanoate, poly-3-hydroxybutyric acid-3-hydroxynonanoate, poly-3-hydroxybutyric acid-3-hydroxydecanoate, poly-3-hydroxybutyric acid-3-hydroxylaurate and the like, which can be synthesized by Pseudomonas putida and the like. The polyhydroxy fatty acid ester has low melting point, obviously improved ductility along with the increase of the number and the content of the carbon atoms of the side chain units, and even has ductility and recoverable deformation similar to an elastomer in some cases. Of these, poly-3-hydroxybutyrate-3-hydroxyhexanoate is particularly useful in the present invention. 3. Reactive monomer
The reactive monomer in the present invention is a vinyl compound having a polar group including, but not limited to: hydroxyl, carboxyl, carbonyl, ester, amino, mercapto, sulfonic acid, ether bond, halogen, peptide bond, acid anhydride bond, etc. The reactive monomer can react with other components in the blend under certain conditions, and then is grafted to other components through covalent bonds, so that a special modification effect is achieved.
The reactive monomer in the present invention is preferably at least one of maleic anhydride, acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, acrylamide, methacrylamide and the like. More preferred reactive monomers are methacrylates, such as at least one of hydroxyethyl methacrylate (HEMA), Glycidyl Methacrylate (GMA), and the like.
4. Initiator
The initiator described in the present invention is a free radical initiator which under certain conditions can decompose an organic compound which generates free radicals, including but not limited to: acyl peroxides, such as Benzoyl Peroxide (BPO); alkyl (dialkyl) peroxides such as di-t-butylperoxide, di-cumylperoxide, cumylperoxide butyl, 3, 5-trimethylcyclohexane-1, 1-diperoxy-t-butyl, 2, 5-dimethyl-2, 5-di-t-butylperoxyhexane, and the like; peresters such as t-butyl peroxypivalate, t-butyl per-2-ethylhexanoate, t-butyl perbenzoate, peroxydodecanoic acid, etc.; alkyl hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, etc.; ketone peroxides, such as methyl ethyl ketone peroxide; azo compounds, such as Azobisisobutyronitrile (AIBN).
The initiator suitable for use in the present invention is preferably at least one of benzoyl peroxide, azobisisobutyronitrile, dicumyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, benzoic acid peroxide, 2, 5-dimethyl-2, 5-di-t-butylperoxyhexane, and the like. More preferred initiators are at least one of benzoyl peroxide, 2, 5-dimethyl-2, 5-di-tert-butylperoxyhexane.
5. Graft-modified thermoplastic cellulose and microbial synthetic polyester blend
The blend of the present invention comprises a thermoplastic cellulose, a biodegradable, microbially synthesized polyester, a reactive monomer and an initiator, wherein the blend comprises 20 to 80 parts by mass of the thermoplastic cellulose, 80 to 20 parts by mass of the microbially synthesized polyester, 0.1 to 10 parts by mass of the reactive monomer and 0.01 to 1 part by mass of the initiator. The blend comprises, in addition to the above components, at least one additive selected from the group consisting of: compatibility agents, inorganic fillers, antioxidants, lubricants, colorants, and the like.
The physical and chemical properties (such as melt viscosity, melt index, etc.) of the polymer blend are mainly determined by the types and composition ratios of the polymers constituting the polymer blend. The polymer type mainly determines the compatibility between the components of the blend, which is a measure of the interaction between different polymers, and when the interaction between different polymers is strong, it can be stably and uniformly mixed on a molecular scale, it is called a miscible (mismixing) system; the interaction between other polymers is weak, and the polymers can be stably and uniformly dispersed in a nano scale or a micron scale although the polymers cannot be mutually dissolved in a molecular scale, so that the blend is called a compatible system; other polymers have weak interactions and even if they are mixed by force, they tend to form separate phase regions, and such blends are incompatible systems. Incompatible systems have distinct phase separation of the different components, i.e.form a phase separated system. Polymer blend glass transition temperature (' Tg") information can be used as a simple judgment basis for the compatibility among the components [ multicomponent polymer-principle, structure and performance, King's institute and editions, 2013, p.20-22 ], if the blend respectively keeps the glass transition temperature of the raw material components, the compatibility among the components is not good, and if the blend only has one glass transition temperature, the compatibility among the components is better. Under the condition of determined polymer types, a certain functional relationship exists between some physical and chemical properties (such as melt viscosity, melt index and the like) of the blend and the composition ratio thereof [ handbook of plastics engineering handbook, Huangrui kingdom, 2000, p.633-637; melt Rheology of Polymer Blends from Melt Flow Index, International Journal of Polymeric Materials,1984,10, p.213-235, one can generally infer and even design Blends with specific properties. In some poorly compatible blending systems, a situation may occur in which the viscosity of the blend is lower than that of the raw material components [ fourth statistical mechanics, golden sun, 1998, p.630-633 ], the reason for this phenomenon being currently uncertain, one of which is explained by the interfacial slippage between the different phases leading to a decrease in the overall viscosity after mixing. Similar phenomena in phaseBlend systems with good compatibility have not been reported, and the blend systems with good compatibility have great potential if the phenomena can be applied to the systems with good compatibility.
The blend composition disclosed by the invention also contains reactive monomers and initiators which are good in compatibility with main components of the blend, such as hydroxyethyl methacrylate, glycidyl methacrylate and the like, the reactive monomers are different from common plasticizers and have high reactivity, free radical reaction is easy to occur in a twin-screw extruder under the conditions of high shear rate, high melt temperature (above 200 ℃) and the existence of the initiators, theoretically, the reactive monomers can be grafted on any C-H bond in the blend components (FIGS. 1 and 2 are two possible structural schematic diagrams generated in the invention), the effect of the reactive monomers is obviously different from that of the plasticizers, and after reactive extrusion, unreacted monomers can be removed in a devolatilization process, so that the situation that the viscosity reduction of a mixed system is not established by simply regarding the reactive monomers as the plasticizers. The initiator is not only added in a small amount, but also easily decomposed at high temperature to generate free radicals to be consumed. After reactive grafting, the interaction between the thermoplastic cellulose and the biodegradable polyester will be stronger due to the presence of the grafting monomer compared to a blend of the same composition without grafting. In conclusion, the special rheological property of the grafted modified thermoplastic cellulose and microbial synthetic polyester blend disclosed by the invention is caused by the special interaction among the components, the compatibility among the components of the mixed system is good, and the phenomenon of viscosity reduction after mixing is less in the compatible mixed system, and related reports are rarely found in literature data.
There are a number of ways in which the properties of the blend can be described, the rule of addition being one of the simplest. The theoretical properties of some polymer blends can be generally presumed by the rule of addition, which can be expressed by the following formula (only the major components are considered here, neglecting the components below 2%):
P＝c1P1+c2P2
p is a property of the blend, c1And P1Is the concentration and nature of component 1; c. C2And P2Is the concentration and nature of component 2. The properties (P) of the thermoplastic cellulose and microbial synthetic polyester blend, such as melt apparent viscosity, melt index and the like, can be calculated by using an addition rule to obtain a theoretically predicted value, namely defined as an addition theoretical value, and the value can be compared with the experimentally detected values, such as apparent viscosity, melt index and the like. The concentration of the components can be expressed by mass fraction or volume fraction, and the mass fraction is selected to calculate a theoretical value in the invention.
A blend composition according to one embodiment of the present invention comprises 20 to 80 parts by mass of a thermoplastic cellulose acetate butyrate ester, 80 to 20 parts by mass of a microbially synthesized polyester such as poly-3-hydroxybutyrate or poly-3-hydroxybutyrate-3-hydroxyvalerate or poly-3-hydroxybutyrate-3-hydroxyhexanoate, 0.1 to 10 parts by mass of a reactive monomer such as hydroxyethyl methacrylate or glycidyl methacrylate and 0.01 to 1 part by mass of an initiator such as benzoyl peroxide or bis-penta peroxide, and is characterized in that the melt viscosity of the blend is at a low shear rate (100 s)-1) Under conditions at least 50% lower than the theoretical value of the mixed addition of the two main starting materials. The melt viscosity of some more preferred compositions of the blends is at low shear rate (100 s)-1) Under conditions at least 65% lower than the theoretical value of the mixed addition of the two main starting materials; some of the most preferred compositions of the blends have melt viscosities at low shear rates (100 s)-1) Under conditions at least 70% lower than the theoretical value of the mixed addition of the two main starting materials.
A blend composition according to one embodiment of the present invention comprises 20 to 80 parts by mass of a thermoplastic cellulose acetate butyrate ester, 80 to 20 parts by mass of a microbially synthesized polyester such as poly-3-hydroxybutyrate or poly-3-hydroxybutyrate-3-hydroxyvalerate or poly-3-hydroxybutyrate-3-hydroxyhexanoate, 0.1 to 10 parts by mass of a reactive monomer such as hydroxyethyl methacrylate or glycidyl methacrylate and 0.01 to 1 part by mass of an initiator such as benzoyl peroxide or bis-penta initiator, and is characterized in that the melt viscosity of the blend is at a high shear rate (1363 s)-1) Under conditions at least 45% lower than the theoretical value of the mixed addition of the two main starting materials. The melt viscosity of some more preferred compositions of the blends is at high shear rate (1363 s)-1) At least 60% lower than the theoretical value of the mixed addition of the two main starting materials under the conditions; the melt viscosity of some of the most preferred compositions of the blends is at high shear rate (1363 s)-1) Under conditions at least 65% lower than the theoretical value of the mixed addition of the two main starting materials.
A blend composition in accordance with one embodiment of the present invention comprises 20 to 80 parts by mass of a thermoplastic cellulose acetate butyrate ester, 80 to 20 parts by mass of a microbially synthesized polyester such as poly-3-hydroxybutyrate or poly-3-hydroxybutyrate-3-hydroxyvalerate or poly-3-hydroxybutyrate-3-hydroxyhexanoate, 0.1 to 10 parts by mass of a reactive monomer such as hydroxyethyl methacrylate or glycidyl methacrylate and 0.01 to 1 part by mass of an initiator such as benzoyl peroxide or bis-penta initiator, characterized in that the melt index of the blend is at least about 90% higher than the theoretical value of the combined addition of the two primary starting materials. Some more preferred compositions have a melt index at least 200% higher than the theoretical value of the mixed addition of the two main starting materials; some of the most preferred compositions have a melt index at least 300% higher than the theoretical value of the mixed addition of the two main starting materials.
The blends of the present invention, which are composed in certain proportions, have "unusually", "unexpectedly" ratios of the main starting materials: the lower theoretical value of the additive mixing of pure thermoplastic cellulose and the starting material of the microbiologically synthesized polyester, i.e. the "concave" curve in the "apparent Viscosity-composition" diagram, which is reflected by the phenomenon of "Melt Viscosity traps" (Melt Viscosity Well), indicates that the blend has an "Anti-Synergistic Effect" of the apparent Viscosity (Anti Effect or Anti-synthetic Effect).
The blends of the present invention, which are composed in certain proportions, have "unusually", "unexpectedly" ratios of the main starting materials: the Melt index (MFR: Melt Flow Rate) of the pure thermoplastic cellulose and the starting material of the microbial synthetic polyester with higher theoretical value of mixed addition is shown as a convex curve in a relation graph of Melt index and composition, and is shown as a Melt index Peak phenomenon, and the blend has Synergistic Effect of Melt index (Synergistic Effect).
6. Method for preparing graft modified thermoplastic cellulose and microbial synthetic polyester blend
The invention relates to a method for preparing a grafted modified thermoplastic cellulose and microbial synthetic polyester blend. The process comprises homogeneously mixing in a continuous process the desired amount of thermoplastic cellulose, the desired amount of microbially synthesised polyester, the desired amount of reactive monomer and the desired amount of initiator in the molten state and extrusion granulating the mixture to obtain a blend characterized by a melt viscosity at a low shear rate (100 s)-1) Under the condition, the additive ratio is at least 50 percent lower than the blending additive theoretical value of the two main starting materials; at high shear rate (1363 s)-1) At conditions at least 45% lower than the theoretical value of the additive blend of the two primary starting materials, and the melt index of the blend is at least about 90% higher than the theoretical value of the additive blend of the two primary starting materials.
The continuous melting preparation method comprises a two-step method and a one-step method. In the two-step method, thermoplastic cellulose powder is firstly granulated by a single-screw or double-screw extruder, then thermoplastic cellulose particles, microbial synthetic polyester particles, reactive monomers and an initiator are uniformly mixed according to a certain proportion, and then a feeding machine is used for adding the mixture into a feeding port of the double-screw extruder according to a certain feeding rate. The feeder can be a weight loss feeder or a volume feeder. The other embodiment is that a plurality of feeders are adopted to respectively meter the thermoplastic cellulose particles, the microbial synthetic polyester particles, the reactive monomers and the initiator into a double screw extruder according to a certain feeding proportion to carry out reaction extrusion granulation.
The one-step method of the invention is that the thermoplastic cellulose powder is directly added into the feeding port of the double-screw extruder by a feeder according to a certain feeding rate without being processed and granulated by heat, meanwhile, the microbial synthetic polyester particles, the reactive monomer and the initiator are added into the feeding port of the double-screw extruder by other feeders according to a certain feeding rate, and are extruded by double screws, and extruded sample strips are cut into granules by a water tank or underwater to prepare the blend particles. The extrudate can also be air cooled by an anhydrous process and then pelletized.
Extrusion temperatures suitable for the present invention are preferably from 140 ℃ to those having a low thermal decomposition temperature of the thermoplastic cellulose and the microbiologically synthesized polyester, more preferably from 140 ℃ to 240 ℃. The rotation speed of the extruder is preferably 50rpm to 1500rpm, more preferably 100rpm to 800 rpm.
Melt blending devices suitable for use in the present invention include a variety of mixers, Farrel continuous mixers, Banbury mixers, single screw extruders, twin screw extruders, multiple screw extruders (more than two screws), reciprocating single screw extruders such as Buss Ko-kneaders (Buss Ko-kneaders), and the like. Preferred processes are continuous melt blending extrusion processes including twin screw extrusion processes. Continuous twin-screw extruders suitable for use in the present invention include twin-screw extruders of different designs, such as the ZSK Mcc18 co-rotating parallel twin-screw extruder manufactured by Coperion, Germany, and the like.
The invention demonstrates that the graft-modified thermoplastic cellulose prepared by the twin-screw continuous melt coextrusion process has an "unexpected" low melt viscosity when blended with a microbial synthetic polyester. One embodiment of the invention is that the melt viscosity of the blend is lower than the theoretical value of the mixed addition of the thermoplastic cellulose and the microbial synthetic polyester starting material under the same conditions. This viscosity reduction is prevalent, including at lower shear rates such as 100s-1And at higher shear rates, e.g. 1363s-1. At 100s-1The melt viscosity of the blend is at least 50% lower than the theoretical value of the mixed addition of the two main starting materials at shear rate. Some more preferred compositions (50 to 20 parts by mass of the microbial synthetic polyester and 50 to 80 parts by mass of the thermoplastic cellulose, 2 to 8 parts by mass of the reactive monomer, and 0.05 to 0.2 parts by mass of the initiator) have a melt viscosity at least 65% lower than the theoretical value of the mixed addition of the two main starting materials, and some most preferred compositions (35 parts by mass of the microbial synthetic polyester and 65 parts by mass of the thermoplastic cellulose, 2 to 6 parts by mass of the reactive monomer, and 0.075 to 0.15 parts by mass of the initiator) have a melt viscosity at least 70% lower than the theoretical value of the mixed addition of the two main starting materials. At 1363s-1Melt of the blend at shear rateThe viscosity is at least 45% lower than the theoretical value of the mixed addition of the two main starting materials, the melt viscosity of a blend of some more preferred compositions (preferably 50 to 20 parts by mass of the microbial synthetic polyester and 50 to 80 parts by mass of the thermoplastic cellulose, 2 to 8 parts by mass of the reactive monomer, and 0.05 to 0.2 parts by mass of the initiator) is at least 60% lower than the theoretical value of the mixed addition of the two main starting materials, and the melt viscosity of a blend of some most preferred compositions (35 parts by mass of the microbial synthetic polyester and 65 parts by mass of the thermoplastic cellulose, 2 to 6 parts by mass of the reactive monomer, and 0.075 to 0.15 parts by mass of the initiator) is at least 65% lower than the theoretical value of the mixed addition of the two main starting materials.
One concrete embodiment of the graft modified thermoplastic cellulose and microbial synthetic polyester blend material prepared by the invention is that the melt index of the blend is higher than the mixed addition theoretical value of two main starting materials. It is preferred that the melt index of the blend of the composition is at least about 90% higher than the theoretical value of the mixed addition of the two main starting materials, more preferably the melt index of the blend of the composition (50 to 20 parts by mass of the microbial synthetic polyester and 50 to 80 parts by mass of the thermoplastic cellulose, 2 to 8 parts by mass of the reactive monomer, and 0.05 to 0.2 parts by mass of the initiator) is at least 200% higher than the theoretical value of the mixed addition of the two main starting materials, and most preferably the melt index of the blend of the composition (35 parts by mass of the microbial synthetic polyester and 65 parts by mass of the thermoplastic cellulose, 2 to 6 parts by mass of the reactive monomer, and 0.075 to 0.15 parts by mass of the initiator) may be at least 300% higher than the theoretical value of the mixed addition of the two main starting materials.
7. Method for preparing graft modified thermoplastic cellulose and microorganism synthetic polyester blend injection molding product
The invention discloses a method for preparing a grafted modified thermoplastic cellulose and microbial synthetic polyester blend injection molding product with special rheological property, which is characterized in that the blend consists of 20 to 80 parts by mass of thermoplastic cellulose, 80 to 20 parts by mass of microbial synthetic polyester, 0.1 to 10 parts by mass of reactive monomer and 0.01 to 1 part by mass of initiator. The blend was prepared by the continuous melt extrusion blending process described above. BlendsAt a low shear rate (100 s)-1) Under the condition, the addition theoretical value is at least 50 percent lower than that of the two main raw materials; at high shear rate (1363 s)-1) Under the condition of at least 45% lower than the addition theoretical value of two main raw materials. The blend has better injection molding processing performance than the main starting material, in the method, the blend is plasticized and melted on an injection molding machine and then is injected into a mold cavity by an injection screw, and the blend melt is separated from an injection mold after being cooled in the mold cavity under certain pressure and dwell time to form an injection molding product.
In the injection molding process, the blend of the present invention is fed into a screw-type injection machine through a hopper, the barrel of the injection machine is heated to a temperature suitable for 160 ℃ to 240 ℃ and more suitably 180 ℃ to 220 ℃ by an electric heating system.
In an injection cycle, the injection machine plasticizes and melts the blend by the mechanical energy of the screw rotation and the thermal energy provided by the heating cylinder, and injects a mass of the blend melt into a closed mold cavity at a pressure and speed for a certain period of time; after injection, the screw continues to apply pressure and maintain a constant pressure (dwell pressure) to increase the density of the blend melt to avoid shrinkage of the injection molded article, with dwell pressures of 5 bar (0.5MPa) to 2000 bar (200MPa) being suitable. The mold then enters a cooling stage, where cooling is accomplished by a cooling fluid (water or other liquid) flowing in a cooling line in the injection mold, suitably at a mold temperature of 5 ℃ to 100 ℃, more suitably at a mold temperature of 10 ℃ to 80 ℃, and most suitably at a mold temperature of 20 ℃ to 60 ℃. The cooling time in the mold is 1 second to 200 seconds, more preferably 5 seconds to 100 seconds, and most preferably 10 seconds to 80 seconds. The cooled injection molded article is released from the mold by an ejector pin (ejector).
The blend of the present invention is injection molded into articles including various sizes and shapes. The blends of the invention allow the preparation of very thin injection-molded articles due to their special rheological properties. The preferred thickness of the injection molded articles of the present invention is from 100 micrometers to 50 millimeters, in some embodiments from 250 micrometers to 25 millimeters, and in still other embodiments from 500 micrometers to 5 millimeters.
The injection molded articles of the present invention include single layer injection molded articles and double or multilayer injection molded articles. The double-layer injection molding machine comprises two independent injection molding systems: 1) an injection molding machine, which is responsible for injecting the core of the double injection molded article, can inject the blend of the invention with special rheological properties; 2) and an injection molding machine is used for injecting the surface layer part of the double-layer injection molding product, the thermoplastic surface layer material is added into the injection molding machine, and the injection molding machine performs injection, pressure maintaining and cooling in a second mold cavity provided with the core layer to form the surface layer, so that the double-layer injection molding product is prepared. Wherein the skin portion may be a specific blend of the present invention but of a different composition than the core portion of the injection molded article, for example the skin portion may be a blend comprising 20 parts by mass of thermoplastic cellulose and 80 parts by mass of a microbially synthesized polyester, and the required amounts of reactive monomers and initiators; the core part contains 60 mass parts of thermoplastic cellulose and 40 mass parts of a microbial synthetic polyester and required amounts of reactive monomers and an initiator; another embodiment is that the skin material is a completely different material from the present invention, such as low density polyethylene, linear low density polyethylene, high density polyethylene, polypropylene, polyolefin elastomer, ethylene propylene rubber, polyethylene terephthalate, polyamide, polyurethane, etc.
The thickness of the core layer in the two-layer injection molded article is 95 to 55% of the total thickness of the two-layer injection molded article (including the core layer and the skin layer). More preferably, the core layer thickness of the two-layer injection molded article is 90 to 60% of the total thickness of the two-layer injection molded article. Further preferred is a two-layer injection molded article wherein the core layer thickness is 80 to 65% of the total thickness of the two-layer injection molded article.
The surface layer portion of the injection molded article has physical properties, chemical properties, mechanical properties, etc. different from those of the core portion due to the difference in composition, and it is a specific embodiment of the present invention that the surface layer portion of the injection molded article has higher toughness than the core portion, and the injection molded article is less likely to be damaged by external stress and impact. Another embodiment is that the surface portion of the injection-molded article has a higher degree of wear resistance than the core portion, and the injection-molded article is less susceptible to damage from external mechanical wear. Multilayer injection molded articles have a wider range of applications than single layer injection molded articles. By making a bi-layer injection molded article, we can effectively incorporate a green, low carbon thermoplastic cellulosic material into an injection molded article. The twin screw extrusion temperature of the blend injection molded article is from 140 ℃ to 240 ℃, preferably from 160 ℃ to 220 ℃. The number of revolutions of the twin-screw extruder is 10 to 500rpm, preferably 20 to 300 rpm.
The grafted modified thermoplastic cellulose and microbial synthetic polyester blend injection molding product with special rheological property prepared by the continuous extrusion blending method disclosed by the invention has lower melt viscosity, higher melt index and better injection molding performance than the mixing addition theoretical value of two main starting materials, is suitable for preparing injection molding products with large volume and thin wall thickness, has wide application potential and obtains better technical effect.
Drawings
FIG. 1 is a schematic structural diagram of a possible HEMA graft-modified PHBV (PHBV-g-HEMA).
FIG. 2 is a schematic diagram of the structure of one possible HEMA graft-modified CAB (CAB-g-HEMA).
FIG. 3180 ℃ is a graph showing the relationship between the apparent shear viscosity and shear rate of each compounded particle.
FIG. 4180 ℃ for 100s for each of the compounded particles-1The dashed line in the figure is the line of the addition theoretical calculation numerical value of PHBV and CAB.
FIG. 5180 deg.C, each compounded particle is 1363s-1The dashed line in the figure is the line of the addition theoretical calculation numerical value of PHBV and CAB.
FIG. 6 DSC cooling curves of the respective compounded particles.
FIG. 7 DSC second temperature rise profile for each compounded particle.
FIG. 8 is a graph showing the relationship between the glass transition temperature and the composition of each compounded particle.
Fig. 9 TGA profile of each compounded particle under air atmosphere.
FIG. 10 is a graph showing the relationship between the melt index (190 ℃,2.16kg) and the composition of each of the blended particles, wherein the dotted line is a line representing the theoretical calculated value of the addition of PHBV and CAB.
FIG. 11 morphology of injection molded bars of each blend.
The invention carries out performance measurement according to the following method:
melt index (MFR) determination method: according to ISO 1133 standard, the melt index meter is adopted to measure, the cylinder temperature is 190 ℃, the weight load is 2.16kg, the diameter of a die is 2.095mm, the length is 8mm, the preheating time is 4min, samples are automatically cut at set time intervals, 5 times of averaging is carried out, and the measurement result is expressed by grams per 10 minutes (g/10 min).
Rheological behavior determination method: measured by a Malvern Instruments Rosand RH7 hot high pressure capillary rheometer with the processing software of Lannch
Figure BDA0001129716430000191
Version 8.60. The test uses a sensor with 10000Psi pressure and a 16/1.0/180 round hole type capillary die. For batch loading compaction at the time of loading, two 0.5MPa preloads and 2 minute preheats were performed prior to testing to ensure complete melting and compaction of the particles at the selected temperature (180 ℃).
Thermogravimetric analysis (TGA): the testing was performed on a Discovery series thermogravimetric analyzer from TA Instruments with the processing software TA Instruments Trios version 3.1.4. The temperature of the isobalance chamber was required to be stabilized at 40 ℃ before testing. During testing, 5-10 mg of sample is weighed and placed in a ceramic crucible, and the test is carried out in the air atmosphere with the flow rate of 20mL/min, the temperature rise range is 30-600 ℃, and the temperature rise rate is 10 ℃/min.
Thermal performance analysis (DSC): the tests were performed on a Discovery series Differential Scanning Calorimeter (DSC) manufactured by TA Instruments, Inc., with the processing software TA Instruments Trios version 3.1.5, equipped with a TA modified cooking System 90 mechanical refrigeration accessory. The testing atmosphere is 50mL/min of nitrogen, and the amount of the sample required by the test is 5-10 mg. The test procedure was as follows: the temperature is stabilized at 40 ℃ first and thenHeating to 250 deg.C at 10 deg.C/min, keeping the temperature for 2min to remove heat history, cooling to-70 deg.C at 10 deg.C/min, and heating to 250 deg.C at 10 deg.C. And recording the temperature reduction process and the second temperature rise process to research the thermal performance of the sample. By DSC measurement, software can be used to directly derive the crystallization temperature ("T") of a samplec"), melting temperature (" T ")m"), glass transition (" T ")g"), enthalpy change (". DELTA.H "), etc.
Detailed Description
The present invention is specifically described by the following examples. It should be noted that the following examples are given solely for the purpose of illustration and are not to be construed as limitations on the scope of the invention, as many insubstantial modifications and variations of the invention may be made by those skilled in the art in light of the above teachings.
Comparative example 1
The poly-3-hydroxybutyrate-3-hydroxyvalerate (PHBV) used in this invention is manufactured by Ningbo Tianan Biotech Co., Ltd under the brand name ENMATTMY1000P. Raw material ENMATTMY1000P PHBV pellets were extruded and pelletized using a PolyLab HAAKE Rheomex OS PTW16 co-rotating twin-screw extruder (screw diameter 16mm, L/D40) from Thermo Fisher scientific Co., USA as comparative example. The extruder has a total of 11 sections from the feed port to the die, numbered 1-11, wherein section 1 serves only as a feed and is not heated. A volumetric particle feeder attached to the extruder, calibrated for feeding the ENMATTMY1000P PHBV raw material was fed into twin screws at a feed rate of 1600 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 206 ℃, and the torque is 48.5-60%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 21.3g/10 min.
Comparative example 2
Cellulose Acetate Butyrate (CAB) used in the present invention was produced by Eastman, USATMCompany, brand EastmanTMCAB-381-0.5. Raw material EastmanTMCAB-381-0.5 powder was pelletized by extrusion using a PolyLab HAAKE Rheomex OS PTW16 co-rotating twin-screw extruder (screw diameter 16mm, L/D. 40) from Thermo Fisher scientific Co., U.S.A.. The extruder has a total of 11 sections from the feed port to the die, numbered 1-11, wherein section 1 serves only as a feed and is not heated. The attached volumetric powder feeder of the extruder is used for Eastman after being calibratedTMCAB-381-0.5 raw material is fed into the twin screw, and the feeding speed is 1600 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 198 ℃, and the torque is 50-54.5%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 8.7g/10 min.
[ example 1 ]
The grafting monomer hydroxyethyl methacrylate (HEMA) used in the invention is an analytical pure product of Tokyo chemical industry Co., Ltd (TCI), and the dosage of the grafting monomer hydroxyethyl methacrylate (HEMA) is 2% of the total mass of PHBV and CAB. The initiator 2, 5-dimethyl-2, 5-di-tert-butyl hexane peroxide (bis-dipenta) used in the invention is an analytically pure product of carbofuran technologies ltd, and the dosage of the initiator is 5 percent of the dosage of HEMA, namely 1 per mill of the total mass of PHBV and CAB. Mixing ENMATTMY1000P PHBV and EastmanTMCAB-381-0.5 in a mass ratio of 4:1, adding the required amount of HEMA and bis-penta, stirring well, melt blending in the above mentioned PolyLab HAAKE Rheomex OS PTW16 co-rotating twin screw extruder, extruding and granulating. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 1600 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm,after stabilization, the melt temperature is about 205 ℃ and the torque is 32.5-36%. The extruder is provided with a circular neck ring with the diameter of 3mm, a sample strip is extruded from the neck ring and is cooled by water bath, the cooling hardening speed of the sample strip is slow, and the sample strip needs to be collected and cut into cylindrical particles with the diameter of about 3mm by a granulator after being completely hardened (about 15 minutes). Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 35.5g/10 min. According to the feeding and processing conditions, besides some side reactions, HEMA graft modified PHBV (figure 1 is a schematic diagram of a possible PHBV-g-HEMA structure) and/or HEMA graft modified CAB structure (figure 2 is a schematic diagram of a possible CAB-g-HEMA structure) can be generated in the system, and the compatibility and interaction among the components can be enhanced while the molecular weight of the components is increased to a certain extent.
[ example 2 ]
Mixing ENMATTMY1000P PHBV and EastmanTMCAB-381-0.5 according to the mass ratio of 13:7, adding the required amount of HEMA and bis-penta, fully stirring uniformly, melting, blending and extruding in the above mentioned polyLab HAAKE Rheomex OS PTW16 co-rotating twin-screw extruder for granulation. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 1600 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 205 ℃, and the torque is 28-32%. The extruder is provided with a circular neck ring with the diameter of 3mm, a sample strip is extruded from the neck ring and is cooled by water bath, the cooling hardening speed of the sample strip is slow, and the sample strip needs to be collected and cut into cylindrical particles with the diameter of about 3mm by a granulator after being completely hardened (about 45 minutes). Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The pellets had a melt index of 48.1g/10min at 190 ℃ under 2.16 kg.
[ example 3 ]
Mixing ENMATTMY1000P PHBV and EastmanTMCAB-381-0.5 at a mass ratio of 1:1, and adding the required amount of HEMA and Bidawu, stirring well, PolyLab HAAKE R mentioned aboveMelt blending and extruding the mixture in a hemex OS PTW16 co-rotating twin-screw extruder for granulation. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 1600 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 204 ℃, and the torque is 27-31%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 54.0g/10 min.
[ example 4 ]
Mixing ENMATTMY1000P PHBV and EastmanTMCAB-381-0.5 in a mass ratio of 7:13, adding the required amount of HEMA and bis-penta, fully stirring uniformly, melt blending in the above mentioned PolyLab HAAKE Rheomex OS PTW16 co-rotating twin-screw extruder, extruding and granulating. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 1600 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 204 ℃, and the torque is 27-34%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 52.8g/10 min.
[ example 5 ]
Mixing ENMATTMY1000P PHBV and EastmanTMCAB-381-0.5 in a mass ratio of 1:4, adding the required amount of HEMA and bis-penta, fully stirring uniformly, melt blending in the above mentioned PolyLab HAAKE Rheomex OS PTW16 co-rotating twin-screw extruder, extruding and granulating. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 1600g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 204 ℃, and the torque is 27-32.5%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 42.6g/10 min.
[ example 6 ]
All 7 of the above particles, including comparative examples 1-2 and examples 1-5, were subjected to rheological behavior measurements on a Malvern Instruments Rosand RH7 hot high pressure capillary rheometer, the test methods being as described above. The apparent shear viscosity of each particle at 180 ℃ is related to the shear rate in FIG. 3. Wherein the shear rate is 100s-1And 1363s-1The apparent shear viscosity versus composition is shown in FIGS. 4 and 5, respectively, with specific values listed in tables 1 and 2.
From FIG. 3, it can be seen that the shear thinning phenomenon, i.e., the shear viscosity decreases with increasing shear rate, is very common in polymer systems, indicating that the basic properties of the system do not change significantly after blending. The apparent shear viscosity of the mixture is substantially equal to that of ENMAT under the same conditionsTMY1000P PHBV and EastmanTMThe viscosity of the system is obviously reduced after mixing under CAB-381-0.5. Referring specifically to fig. 4 and 5, it can be seen that the apparent shear viscosity of the particles after blending is lower than that of either of the pure starting materials, and the viscosity curve is "concave," i.e., an unexpected "viscosity trap," which indicates that the particles after blending exhibit a decrease in viscosity at both high and low shear rates.
Hydroxyethyl methacrylate (HEMA) added as a small molecule to the whole can be considered as a plasticizer, but different from the common plasticizer, HEMA has higher reactivity and is very easy to generate radical reaction in a twin-screw extruder under the conditions of high shear rate, high melt temperature (above 200 ℃) and the existence of initiator bis-di-five, theoretically, reactive monomers can be grafted on any C-H bond in the blend components (fig. 1 and fig. 2 are two possible structural schematic diagrams generated in the invention), and obviously, the HEMA is simply considered as the plasticizer to explain that the viscosity of the mixed system is reduced and is not true. The adding amount of the diindipentan is small, the diindipentan is easy to decompose at high temperature to generate free radicals to be consumed, and plays a role in preventing the reduction of the molecular weight of raw materials in the processing process, namely preventing the reduction of the viscosity of a system, so the adding of the diindipentan is not a reason for the reduction of the viscosity of a mixed system. In conclusion, the viscosity reduction of the mixed system is caused by special interaction among the components, the compatibility among the components of the mixed system is good, and the phenomenon of viscosity reduction after mixing is less in the compatible blending system, and related reports are rarely made on literature data.
Some of the performance parameters after blending of the polymers can be inferred from the theoretical values of addition, determined according to the following formula (only the main components are considered here, neglecting the components at a level of 2% and below):
P＝c1P1+c2P2
wherein P is the theoretical value of addition, P1The corresponding parameter values for component 1 in the mixture, c1Is its mass fraction, P2The corresponding parameter value of component 2 in the mixture, c2Is the mass fraction thereof. If the measured value of the mixture parameter differs more from the theoretical value of the addition, a more pronounced synergistic (or anti-synergistic) action between the components is indicated.
From Table 1, it can be found that when the shear rate is 100s-1When the actual blend apparent shear viscosity is about 48.3% (example 1) to 47.8% (example 4) lower than the addition theoretical value.
From Table 2, it can be found that when the shear rate is 1363s-1When the actual blend apparent shear viscosity is about 44.8% (example 1) to 65.1% (example 4) lower than the addition theoretical value.
[ example 7 ]
All of the above 7 particles, including comparative examples 1-2 and examples 1-5, were subjected to Differential Scanning Calorimetry (DSC) tests according to the procedure described above, and the temperature decrease curves and the second temperature increase curves are shown in fig. 6 and 7. Can be directly obtained from the raw materials by softwareTo the glass transition temperature ("T") of the respective particlesg") versus composition is shown in fig. 8.
As can be seen from FIG. 6, the crystallinity of PHBV was significantly reduced after the addition of CAB, and almost no peak was observed in the DSC temperature decrease curves of examples 1 to 5. On the second temperature rise curve, examples 3-5 have substantially no crystallization and melting signals, except for examples 1-2, which have temperature rise crystallization peaks and melting peaks (where both the crystallization and melting peaks of example 2 are smaller). From FIGS. 6-8, it can be seen that the mixed particles all have only one glass transition temperature ("T")g") indicates that the compatibility of the components in the blended particles is good, and TgThe value of (a) increases with increasing CAB content.
[ example 8 ]
All 7 of the above seeds, including comparative examples 1-2 and examples 1-5, were subjected to thermogravimetric analysis (TGA) testing according to the procedure described above, and the results of the testing are shown in fig. 9. As can be seen from the figure, the thermal decomposition curves of the particles after blending are all between the curves of comparative examples 1-2, indicating that the thermal stability of CAB and PHBV is not much changed before and after blending, which is consistent with the expectation. And the thermal decomposition curves of the blends each present two distinct stages, corresponding to the decomposition temperatures of the two main raw materials (PHBV and CAB) among them, and moreover, the ratio of the two thermal decomposition stages corresponds to the composition of the blend.
[ example 9 ]
All of the above 7 types of particles, including comparative examples 1-2 and examples 1-5, were subjected to melt index (MFR) testing (190 ℃,2.16kg) according to the procedure described above, and the relationship between the measured MFR values and the composition is shown in FIG. 10. The specific values obtained from FIG. 10 are shown in Table 3, which includes the "theoretical values for addition" mentioned above.
From Table 3, it can be seen that the actual melt index of example 1 after melt blending of the components is 16.8g/10min higher than the theoretical value of addition, the percentage is about 89.4%, which is the smallest percentage value among examples 1-5; the actual melt index of example 4 was 39.7g/10min higher than the theoretical value of addition, the percentage was about 303%, and the percentage was the largest among examples 1-5. The other examples are between 89.4% and 303% higher than the addition theory. These exceptionally high melt indices are unexpected, rare in compatible polymer blend systems, and not yet discovered in CAB and PHBV blends.
[ example 10 ]
The above 7 types of particles, including comparative examples 1-2 and examples 1-5, were processed at HAKKE of Thermo Fisher scientific Co., USATMInjection molding experiments were performed in a MiniJet II micro injection molding machine. The mold is a 557-2295-60 × 10 × 1 mold produced by Thermo Fisher science and technology, and the temperature of the material cavity and the temperature of the mold in the experimental process are respectively set as follows: 200 ℃ and 50 ℃. Setting the pressure at 300bar in the injection molding process for 5s, maintaining the pressure at 100bar for 60s in the subsequent pressure maintaining process, demolding, and collecting injection molded sample bars.
Under the same injection molding conditions, the injection molding properties of the materials are different due to the difference of the flow properties of the materials, and the injection molding properties are reflected in the filling degree of samples obtained by injection molding. All 7 injection molded bars are shown in FIG. 11, where the shortest injection molded bar was produced from the starting material CAB (comparative example 2), indicating the lowest flowability under these conditions. The injection-molded bars prepared from the starting material PBS (comparative example 1), although somewhat longer than comparative example 2, still did not fill the mold. After blending, the sample bars basically and completely fill the mold, which shows that the injection molding performance is obviously improved. Due to the improved rheological properties after blending, the blends of the invention allow the production of larger, thinner injection-molded parts under the same conditions. While high flowability also offers the possibility of producing more injection-molded articles in the same time.
TABLE 1180 ℃ shear rate of 100s-1Measured apparent shear viscosity, theoretical apparent shear viscosity, and difference and percentage difference between the two
Figure BDA0001129716430000261
Table 2180 ℃ C. at a shear rate of 1363s-1Measured apparent shear viscosity, theoretical apparent shear viscosity, and difference and percentage difference between the two
Figure BDA0001129716430000271
Table 3 measured melt index (190 ℃,2.16kg) and addition theoretical melt index and the difference and percent difference between the two
Figure BDA0001129716430000272

Claims (3)

1. An injection molding product contains a blend of graft modified thermoplastic cellulose and microbial synthetic polyester, and the blend of the graft modified thermoplastic cellulose and the microbial synthetic polyester comprises the following components in parts by mass:
(1)20 to 80 parts of thermoplastic cellulose;
(2)80 to 20 parts of a microbiologically synthesized polyester;
(3)0.1 to 10 parts of a reactive monomer;
(4)0.01 to 1 part of an initiator;
characterized in that the blend has a reactive monomer grafted onto at least one of the thermoplastic cellulose and the microbial synthetic polyester; the reactive monomer is hydroxyethyl methacrylate; the thermoplastic cellulose is cellulose acetate butyrate; the microbial synthetic polyester is poly 3-hydroxybutyric acid-3-hydroxyvalerate; the initiator is at least one of benzoyl peroxide, azodiisobutyronitrile, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoic acid peroxide and 2, 5-dimethyl-2, 5-di-tert-butyl peroxy hexane;
the melt viscosity of the blend was 100s at low shear rate-1Under conditions at least 50% lower than the theoretical value of the additive blend of the two main starting materials, at a high shear rate of 1363s-1At least 45% lower than the blended addition theoretical starting material of the two main starting materials.
2. A method for preparing the injection-molded product of claim 1, wherein the required amount of each component is mixed and granulated, melted and plasticized on an injection molding machine, and then injected into a mold cavity by an injection screw to form a blend melt, and the blend melt is subjected to pressure maintaining in the mold cavity, cooled and separated from the injection mold to form the injection-molded product.
3. A method for preparing the injection molding product of claim 1, wherein the core layer material or the blend is added to a double-material co-injection molding machine, is injected into a mold cavity by an injection screw after being melted and plasticized, is separated from an injection mold after being subjected to pressure maintaining and cooling to form the core layer of the injection molding product, and the surface layer material or the blend is added to another injection molding machine and is injected, pressure maintaining and cooling in another mold cavity provided with the core layer to form a surface layer, so that the double-layer injection molding product is prepared; wherein, at least one layer of the double-layer injection molding product is the blend of the grafted modified thermoplastic cellulose and the microbial synthetic polyester, and when the two layers are the blend of the grafted modified thermoplastic cellulose and the microbial synthetic polyester, the blend of the grafted modified thermoplastic cellulose and the microbial synthetic polyester in the two layers has different composition ratios of the thermoplastic cellulose, the microbial synthetic polyester, the reactive monomer and the initiator.
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