JPH08165414A - Biodegradable resin composition - Google Patents

Abstract

PURPOSE: To obtain a completely biodegradable resin composition having excellent moldability and mechanical performances. CONSTITUTION: This biodegradable resin composition comprises a poly-3- hydroxybutyric acid having >=5,000P viscosity and a polycaprolactone having >=3,000P viscosity both at 185 deg.C under conditions of 1mm diameter and 10mm length of capillary dimensions and 10kgf/cm<2> pressure. The composition is excellent in moldability and mechanical performances.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention has excellent moldability and mechanical performance, and is used as a packaging member for chemicals, cosmetics, foods and industrial materials / machines, machine parts, fibers, monofilaments, clothing and the like. The present invention relates to a resin composition having excellent biodegradability.

[0002]

2. Description of the Related Art A large number of plastics have hitherto been used in various industrial fields as molding materials for packaging materials, clothing, fibers, monofilaments and industrial machine parts. At the same time, from the standpoint of environmental protection, the reuse of plastics is called for, and the development of biodegradable polymer materials that are completely decomposed by biodegradable polymer materials that are completely decomposed by the action of microorganisms under natural environmental conditions. Is socially strongly demanded.

Poly-3-hydroxybutyric acid (hereinafter abbreviated as PHB) is generally manufactured by a fermentation method using a microorganism, and polycaprolactone (hereinafter abbreviated as PCL) is manufactured by a chemical synthesis. PHB and PCL have the biodegradability that they are completely decomposed by the action of microorganisms widely distributed in the natural world, and because they are thermoplastic, they are actively investigated for use in various applications by existing molding methods. Is being done. However, it is known that PHB lacks thermal stability in a molten state and is difficult to mold, and the molded product obtained has a small elongation and is hard and brittle.
On the other hand, although PCL has a large elongation, it has a drawback of low heat resistance because of its low melting point of 60 ° C. For this reason,
Although PHB and PCL have excellent biodegradability to meet social demands for environmental protection, they have not yet been fully utilized in various fields.

Further, Japanese Patent Laid-Open No. 3-157450 discloses a PH
It has been shown that the presence of the copolymer of B and PCL makes it possible to obtain a film having good elongation. However, on the contrary, this film causes a decrease in crystallization rate and a gas barrier performance due to the presence of the copolymer. Further, the present inventors have recently shown that a practical biodegradable resin can be produced by defining the melt viscosity ratio of PHB and PCL. However, in this case, when trying to obtain a biodegradable resin by mixing PHB and PCL, not only the melt viscosity ratio but also the PHB used
If the melt viscosity of PCL itself is low, melt molding may become difficult, or the mechanical performance of the obtained molded product may not be sufficiently satisfied.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above problems found in the prior art and is excellent in moldability.
It is an object of the present invention to provide a highly practical biodegradable resin composition that gives a molded article having excellent physical properties.

[0006]

The inventors of the present invention have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, the viscosity at 185 ° C. is as follows: capillary size, diameter 1 mmφ, length 10
mm under a pressure of 10 kgf / cm ²
A resin composition having biodegradability and excellent in moldability and mechanical performance, which is characterized by comprising PHB of poise or more and PCL of 3,000 poise or more.

The PHB used in the present invention may be chemically synthesized or produced by a microorganism.
For example, genus Alcaligenes, genus Azotobacter, methylobacterium (Methyl
It can be produced by a known fermentation method using a bacterium of the genus obacterium, the genus Nocardia, the genus Pseudomonas and the like. Regarding the method for separating and purifying PHB from the PHB-containing cells obtained by the fermentation method, for example, US Pat.
101533, No. 3275610, and European Patent No. 15123 describe a purification method using a solvent such as pyridine, methylene chloride, 1,2-propylene carbonate, chloroform and 1,2-dichloroethane, and Japanese Patent Application No. 323019 describes a method of crushing bacterial cells with a high-pressure homogenizer, separating PHB, and treating the separated PHB with an oxygen-based bleaching agent.

PCL, which is another constituent of the composition of the present invention, is a polyester synthesized by a chemical reaction such as a ring-opening polymerization reaction of caprolactone,
It has been revealed that this PCL is also completely biodegraded by the action of microorganisms widely distributed in nature.

In the present invention, the PHB used has a viscosity of 5,000 POISE or more, and the PCL has a viscosity of 3.0.
It is necessary to be 00 POISE or more. This is because if PHB having a lower viscosity is used,
The viscosity of the other component, PCL, greatly depends on the moldability and mechanical performance, and as a result, molding can be performed only in a narrow range in consideration of the melt viscosity ratio of PHB and PCL, and the required performance cannot be obtained. There is a risk. Also, P
If a CL having a viscosity lower than this is used, a uniform melt mixture is not provided, and there is a risk of inconveniences such as uneven discharge during molding, uneven surface of the molded product, and poor appearance of the molded product. is there. Therefore, the melt viscosity is 5,000
PHB of 0 POISE or more and melt viscosity of 3,000 PO
A biodegradable resin composition comprising PCL that is ISE or higher provides a biodegradable resin composition that is excellent in moldability, mechanical strength, heat resistance, and gas barrier properties without considering factors such as melt viscosity ratio. Can be obtained.

The resin composition of the present invention may contain conventional auxiliary additives such as inorganic fillers, pigments, antioxidants and plasticizers. The composition of the present invention includes injection molding, injection blow molding, injection stretch blow molding, extrusion, extrusion blow molding, extrusion stretch blow molding, stretching, rolling, thermoforming, spinning,
By a molding processing method that can be generally applied to thermoformable resins such as spinning accompanied by stretching, spinning, and weaving, sheets, films, soft and hard containers / bottles, tubes, monofilaments, fibers, nonwoven fabrics, woven fabrics, machine parts, It can be converted into sports equipment parts products. As a particularly specific application of these molded products, materials that are impossible or difficult to collect or reuse after use, such as medical instruments and equipment, containers for foods, drugs, fragrances, garbage bags, fishing lines, fishing nets, etc. Yarn, net, medical cloth, industrial cloth, other industrial and agricultural materials, and the like.

[0011]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. The melt viscosity and tensile properties shown below were measured as follows. (1) Melt viscosity device: Capillary rheometer (Co., Ltd.)
Shimadzu, Flow tester CFT-500) Capillary dimensions: Diameter 1 mm φ Length 10 mm Measuring temperature: 185 ° C. Pressure: 10 kgf / cm ² (2) Tensile test device: Tensile tester (Toyo Seiki Co., Ltd., Strograph V1-) C) Test piece shape: strip type length 100 mm, width 10 m
m, 50 mm between chucks Peeling speed: 50 mm / min Measurement conditions: Temperature 23 ° C or 40 ° C, relative humidity 50%

Examples 1 to 4 Protomonas e, a bacterium that has been deposited at the Institute of Biotechnology, Institute of Biotechnology, AIST.
xtorquens) K (consignment number: FERM BP-354
Using 8), continuous culture was performed aerobically using methanol as a carbon source. The culture conditions are a culture temperature of 32 ° C. and a culture pH of 6.
5. The average residence time was 40 hours, and continuous culture was performed so that the nitrogen supply rate was the rate-determining factor for bacterial cell growth. According to recent literature, this bacterium is a methylobacterium (Methylobac
terium) (IJBousfield and
PNGreen; Int. J. Syst. Bacteriol., 35,209 (1985), T.
Urakami et al .; Int.J.Syst.Bacteriol., 43,504-513 (1
993)). The bacterial cells obtained by continuous culturing were used in the above-mentioned Japanese Patent Application No. 5-
According to the method for separating and purifying PHB described in 323019, after destroying with a high-pressure homogenizer, PHB was centrifuged, and the separated PHB was first treated with protease and then treated with hydrogen peroxide to obtain high-purity PHB.

The PHB was pelletized using a screw type extruder. The PHB pellets thus obtained had a melt viscosity of 6310 poise. This PHB and PCL having a melt viscosity of 35400 poise ("Plaxel H-7" manufactured by Daicel Chemical Industries, Ltd.) were mixed so as to be PHB parts by weight of 20%, 40%, 60% and 80%, respectively, and then a single screw extruder was used. (Manufactured by Toyo Seiki Co., Ltd., Labo Plastomill, screw diameter: 20 mm) is used, and the cylinder temperature is 170 to 190 ° C. by the T-die / cooling roll method (cooling roll temperature: 25 to 55 ° C.), thickness about 2
A sheet of 00 μm was prepared. Cut a strip-shaped test piece 100 mm long and 10 mm wide from the obtained sheet, and
A tensile test was performed at 3 ° C. Table 1 shows the results.

Comparative Example 1 Using PCL having a melt viscosity of 3,400 poise, a thickness of about 200 μm was obtained in the same manner as in Examples 1 to 4.
The sheet of was produced. 100m length from the obtained sheet
A strip-shaped test piece of m and a width of 10 mm was cut out and a tensile test was performed at 23 ° C. Table 1 shows the results.

Comparative Examples 2-3 PHB used in Examples 1-4 and melt viscosity of 220 poi
PCL (separated from Daicel Chemical Industries Ltd. "Plaxel H-4" whose melt viscosity has been lowered by heating), which is SE, is blended so as to have PHB parts by weight of 40% and 60%, respectively. A sheet having a thickness of 200 μm was produced in the same manner as in the method shown in FIGS. In either case, the nonuniformity of the surface and the poor appearance were remarkable, and it was impossible to prepare a sheet.

Examples 5 to 8 Protomonas extorence
quens) K (accession number: FERM BP-3548), and aerobically and continuously cultivated using methanol as a carbon source. The culturing conditions were a culturing temperature of 32 ° C., a culturing pH of 6.5, and an average residence time of 40 hours. The PHB was pelletized using a screw type extruder. The PHB thus obtained had a melt viscosity of 9310 poise. This PHB and PCL with a melt viscosity of 3400 poise
("Placcel H-7" manufactured by Daicel Chemical Industries, Ltd., whose melt viscosity has been lowered by heating) and PHB parts by weight of 20%, 40%, 60%, and 80%, respectively, and then mixed. A sheet having a thickness of about 200 μm was produced in the same manner as in the methods shown in Examples 1 to 4. A strip-shaped test piece having a length of 100 mm and a width of 10 mm was cut out from the obtained sheet and subjected to a tensile test at 23 ° C. Table 1 shows the results.

Examples 9 to 12 The sheets obtained in Examples 1 to 4 were subjected to a tensile test at 40 ° C. The results are shown in Table 2.

Comparative Example 4 The sheet obtained in Comparative Example 1 was subjected to a tensile test at 40 ° C. The results are shown in Table 2 together with Comparative Example 1.

[0019]

[Table 1] Table 1 Mixing ratio Melt viscosity Melt viscosity Tension Tension Tension Example Temperature PHB / PCL (POISE) Strength Elongation Modulus (℃) (wt / wt) PHB PCL (kgf / mm ² ) (%) (kgf / mm ² ) Example 1 23 20/80 6310 35400 1.5> 500 42 Example 2 23 40/60 6310 35400 1.7 370 75 Example 3 23 60/40 6310 35400 2.6 17 142 Example 4 23 80/20 6310 35400 2.6 3.3 178 Example 5 23 20/80 9310 3400 1.5> 500 42 Example 6 23 40/60 9310 3400 2.0> 500 97 Example 7 23 60/40 9310 3400 2.7 126 164 Example 8 23 80/20 9310 3400 3.0 1.9 225 ────────────────────────────────── Comparative Example 1 23 0/100-3400 1.4> 500 26

[0020]

[Table 2] Table 2 Measurement Mixing ratio Tensile strength Tensile elastic modulus Example Temperature PHB / PCL (kgf / mm ² ) (kgf / mm ² ) (℃) (wt / wt) Example 9 40 20/80 1.2 49 Implementation Example 10 40 40/60 1.2 51 Example 11 40 60/40 1.7 107 Example 12 40 80/20 1.8 142 ───────────────────────── ────── Comparative example 1 23 0/100 1.4 26 Comparative example 4 40 0/100 0.7 10

[0021]

According to the present invention, it is possible to provide a completely biodegradable resin molded product which is excellent in moldability and has excellent mechanical strength such as tensile performance without considering the melt viscosity ratio of PHB and PCL. You can

Claims (1)

[Claims] 1. Viscosity at 185 ° C., capillary size, diameter 1 mmφ, length 10 mm, pressure 10 kgf /
Under conditions of cm ² , poly- of 5,000 poise or more
A biodegradable resin composition comprising 3-hydroxybutyric acid and 3,000 poise or more polycaprolactone having excellent moldability and mechanical performance.