JPS6213449A - Saponified ethylene copolymer resin composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. which has excellent gas barrier properties, transparency and chemical resistance, is freed from the problem of forming pinholes and gives films and molding having excellent rigidity and resistance to heat and impact, consisting of a saponified ethylene/vinyl acetate copolymer and a terminal-modified polyamide. CONSTITUTION:100pts.wt. saponified ethylene/vinyl acetate copolymer (A) having a degree of saponification of 80% or above and contg. 5-50mol% of a repeating unit of the formula derived from ethylene monomer is uniformly mixed with 5-150pts.wt. terminal-modified polyamide (B) rich in the terminal NH2 group, which contains at least 8X10<-5> equivalents of terminal NH2 group/g, not more than 3X10<-5> equivalents of terminal COOH group/g and a relative viscosity of 2.1-3.5. The mixture is melt-kneaded in an extruder or a kneader.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a resin composition of a saponified ethylene copolymer. Specifically, the present invention relates to a resin composition in which a specific polyamide is blended in a specific ratio to a highly saponified ethylene-vinyl acetate copolymer. A film or container formed by extrusion molding from the resin composition of the present invention has excellent gas barrier properties and impact resistance (pinhole resistance).

In particular, it can be suitably used for food packaging films or containers. Furthermore, molded articles made by injection molding from the resin composition of the present invention have excellent not only rigidity and heat resistance but also impact strength, and can be used as engineering plastics for various functional parts.

[Description of prior art]

General D. Saponified product of ethylene-vinyl acetate copolymer C is hereinafter abbreviated as EVOH. ) has extremely good gas barrier properties and is therefore used as a material for forming food packaging films or containers that require a low oxygen gas permeation rate. In addition, FiVOH especially blended with glass fiber has high rigidity and heat resistance, so metal parts (A
/, die casting), Zn die casting, etc.) for various functional parts.

However, this EVOH has the drawback that the molded product is hard and brittle, and is subject to restrictions in terms of its use. For example 1
When used as a film or sheet for food packaging,
The film may be torn during packaging, moving or transporting the packaged items.

Excellent gas barrier with easy pinhole formation
I am unable to make full use of my sexuality.

Furthermore, even when used in injection molded products, complaints such as cracks often occur, especially immediately after molding and at low temperatures.

Generally, the physical properties and moldability of EVOH change depending on the ethylene content and saponification degree, and as the ethylene content increases and the saponification degree decreases.

Although moldability and impact resistance become good, gas barrier properties, rigidity, and heat resistance deteriorate. For this reason.

There were strong expectations for a new technology that would improve impact resistance without significantly impairing the gas barrier properties, rigidity, and heat resistance that characterize EVOH.

As a means to improve the disadvantages of EVOH,
There is a method using a resin composition in which VOH is mixed with various polyamides.For example, Japanese Patent Publication No. 44-24277,
Japanese Patent Publication No. 48-22833, Japanese Patent Publication No. 50-1213
No. 47, JP-A-54-78749, JP-A-Sho 5
This method is well known from publications such as Japanese Patent Application Laid-open No. 4-78750 and Japanese Unexamined Patent Publication No. 55-34956.

In the above method, since EVOH and polyamide are highly compatible with each other, by blending polyamide with KVOH, the polyamide acts to improve impact resistance, and the original excellent properties of EVOH are improved. It does not impair gas barrier properties, rigidity, or heat resistance.

However, this resin composition, which is a mixture of EVOH and polyamide, has major problems.

That is, when *EV OH and polyamide are mixed in a molten state, a chemical reaction occurs between the two, the melt viscosity increases, and eventually gelation occurs, making molding impossible.

This gelation becomes more pronounced as the molding temperature increases, so methods have been proposed to use various copolyamides with low melting points as polyamides.
For example, JP-A-54-78749, JP-A-54-
Examples include methods disclosed in Japanese Patent Application Laid-open No. 78750, Japanese Patent Application Laid-Open No. 55-34956, and the like.

However, even with these methods, it is difficult to completely prevent gelation, and gvoH
A practical method for improving the impact resistance of is desired.

[Requirements and effects of the present invention]

As a result of intensive research aimed at improving the impact resistance of such EVOH, the present inventors found that a resin composition in which a specific EVOH is mixed with a polyamide modified with a specific end group does not gel during molding. It has been found that the gas barrier properties, rigidity, and heat resistance of the molded product are not impaired, and the pinhole resistance and impact resistance are further improved.

completed this invention.

That is, the present invention relates to a copolymer of ethylene and vinyl acetate that has 5 to 50 moles of repeating units (-CH2-CH2-) based on ethylene monomer and has a degree of saponification of about 80 or more. 100 parts by weight of a compound, and a relative viscosity of 2.1 to 3.5.

An ethylene system characterized by comprising 5 to 150 parts by weight of an amino terminal-rich terminal-modified polyamide having 8 x 10 equivalents/1 or more of amino terminal groups and 3 x 10 equivalents/g or less of carboxy terminal groups. The present invention relates to a resin composition of a saponified copolymer.

The resin composition of this invention.

(a) When molding films, containers, injection molded products, etc., it will not gel and become difficult to mold;
Maybe.

(b) The molded product has sufficient gas barrier properties and rigidity.

Since it has heat resistance and improved bottle ball resistance or impact resistance, it can be suitably used as a packaging material or functional parts.

[Detailed explanation of each requirement of the present invention]

The saponified copolymer of ethylene and vinyl acetate (EVOH) used in the present invention contains repeating units I based on ethylene monomer in a molar ratio of 5 to 50 based on the total amount of the polymer.
Preferably 10 to 45 molt, particularly preferably 15 to 4 molt.
It has a ratio of 0 molti and a saponification degree of about 80.
"Saponified ethylene-vinyl acetate copolymer" having a content of at least 90%, preferably at least 90%, particularly preferably at least 95%.
It is.

The saponified product (EVOH) is produced by saponifying an ethylene-vinyl acetate copolymer obtained by polymerizing ethylene monomer and vinyl acetate monomer by a known method, and is produced by saponifying an ethylene-vinyl acetate copolymer obtained by polymerizing ethylene monomer and vinyl acetate monomer, and If the unit I is less than 5 mole based on the saponified product, the moldability of the resin composition obtained using such a saponified product will be poor, so it is not suitable. If it has more than 50 mol.

It is not suitable because the gas barrier properties, rigidity, and heat resistance of molded products formed from resin compositions containing such saponified products deteriorate.

In this Yorikiri, the degree of polymerization of EVOH is not particularly limited, but the intrinsic viscosity (15%
KVOH (measured at 30° C.) of 0.07 to 0.17 is preferably used.

Polyamides that can be used in this invention include nylon 6° and nylon 610. Nylon 12. There are such things.

In particular, from the viewpoint of compatibility with EVOH and lowering the molding temperature, nylon 6 paste copolymers 1, such as 6/66 copolymer, 6
/12 copolymer, 66/610/6 copolymer, etc. are preferred. The feature of the present invention is the use of a polyamide modified with a specific terminal group, and the amino terminal group is 8×1.
0 equivalent weight is 77 or more and the carboxyl terminal group is 3×1
It is necessary that the ratio is 0 equivalent/1 or less. KVOH using polyamide that does not satisfy these conditions for end groups.
When blended with, the melt viscosity increases during molding, making continuous molding difficult over a long period of time. Known methods can be applied to obtain polyamides having such terminal groups.
For example, it can be obtained by adding diamino such as aliphatic diamino such as hexamethylene diamino or aromatic diamino such as metaxylene diamino during polymerization.

Regarding the degree of polymerization of the polyamide used in the present invention, the relative viscosity is 2.1 to 3.5. Preferably.

Those in the range of 2.2 to 3.2 are used.

In order to obtain terminal groups as used in the present invention, it is difficult to polymerize materials with a high relative viscosity.

If the relative viscosity is too low, the desired improvement in pinhole resistance or impact resistance cannot be achieved when blended with KVOH.

゛ The resin composition of the present invention has the above-mentioned EVOH100
parts by weight and 5 to 150 parts by weight of the aforementioned polyamide.

The resin composition preferably contains 10 to 100 parts by weight of a saponified ethylene copolymer as a polymer component.

In the resin composition of the present invention, if the ratio of polyamide to saponified material is too small, the mechanical properties such as pinhole resistance or impact resistance of molded products formed from such resin composition may be poor. However, if the ratio of polyamide to the saponified product is too large, the gas barrier properties, rigidity, etc. of the molded product formed from such a resin composition will be insufficient. It's not appropriate.

The method for preparing the resin composition of the present invention is not particularly limited, and can be carried out by a commonly known method of "mixing the saponified product and polyamide."

That is, as a known method for mixing the saponified product and polyamide, for example, mixing the saponified product and polyamide,
A method of uniformly mixing pellets, powder, etc., then melting and kneading with an extrusion kneader to form pellets, and using the pellets for molding, or a method of uniformly mixing pellets, powder, etc. of the saponified product and polyamide. and feed the mixture directly to a film molding machine or injection molding machine.

A method of molding while kneading in the molding machine is suitable.

In order to make films, containers, injection molded products, etc. from the resin composition of this invention, 9 ordinary extrusion molding methods and injection molding methods can be applied, and in these moldings, no gelation occurs for a long time, Stable continuous molding is possible.

Films, sheets, etc. made of the resin composition of the present invention have excellent gas barrier properties and pinhole resistance, as well as transparency and chemical resistance, and have high utility value. Furthermore, injection molded products made from the resin composition of this invention have excellent rigidity, heat resistance, and impact resistance, as well as wear resistance and chemical resistance, and are used as engineering plastics for various functional parts. can.

Note that the resin composition of this invention may contain other components.

For example, pigments, heat stabilizers, antioxidants, weathering agents.

It also includes those to which appropriate amounts of crystallization accelerators, lubricants, fillers, plasticizers, etc. are added. In particular, those filled with glass fiber are useful as injection molded products because of their high rigidity, creep resistance, and heat resistance.

〔Example〕

EXAMPLES The resin composition of the present invention will be described in more detail below with reference to Examples and Comparative Examples. How to measure the physical properties of the film in each Example or Comparative Example.

It was measured according to the method described below.

(1) Oxygen permeability Measured using an oxygen gas permeability measuring device (manufactured by Modern Control Co., Ltd., Model 0XYTRAN-100) under conditions of 20° C. 2 in an absolutely dry state.

(2) Pinhole resistance A tensile test in the pulling direction (M, D,) was conducted in accordance with ASTM D-882 in an absolutely dry state at 2°C.

The tensile modulus and elongation were used as measures of pinhole resistance. That is, in the above test, the lower the tensile modulus and the higher the elongation rate, the better the pinhole resistance is evaluated.

In addition, in the following Examples and Comparative Examples, the relative viscosity was measured using JlsK-6810, and the amino terminal group and carboxy terminal group were measured using JlsK-6810.

Waltz, J.E., Anal Chsm 19
, 448 (1947). The amino end groups were determined by dissolving the sample in a mixed solution of phenol and methanol, and neutralization titration with 1201 hydrochloric acid using a methyl orange xylene cyatool FF indicator. , was determined by dissolving a sample in hot benzyl alcohol and performing neutralization titration with an aqueous NaOH solution using a phenolphthalein indicator.

Example 1 A saponified product of ethylene-vinyl acetate copolymer (EVOH) containing 1 t"38 mole of repeating units based on ethylene monomer, with a degree of saponification of 99%, an intrinsic viscosity of 0.14, and a melting point of 173 °C )” to 100 parts by weight, relative viscosity 2.
7. Nylon 6 with amino end groups 9.7 X 10"5 equivalents/y, carboxy end groups 2.OX 10"5 equivalents/g
(A) 43 parts by weight were blended in the form of pellets. The mixture was supplied to an extrusion molding machine (T-Guy extrusion molding machine, nuclear diameter is 408), and melt extrusion was performed at 250°C to form a resin consisting of the EVOH and nylon 6 (A) polymer components. The film-like product was extruded and then cooled and solidified on a casting drum whose surface temperature was 70°C to form a film with a thickness of about 50 μm. The following physical properties were evaluated for this film.

Regarding the gelling behavior during molding, the molding temperature was set at 250°C.
°C and strict conditions against gelation.

The time required for gel to form on the film was measured.

These results are shown in Table 1.

In the above-mentioned film formation, the resin composition used did not cause gelation, and no gelled product was generated even when molded at a high temperature of 250°C or 10 hours after molding.

The film obtained by the above film formation had significantly improved pinhole resistance and also had good gas barrier properties.

Example 2 Instead of nylon 6G), 6/66 copolymer (A) [
The molar ratio (6/66) of the constitutional units of nylon 6 and nylon 66 is 85/15, and the melting point is 195°C.
1 relative viscosity is 2.8 and amino end group is 9.0X10
Example 1 except that 43 parts by weight of 2.2×10 carboxy end groups were used.
A film was formed in the same manner as above.

The results are shown in Table 1.

The obtained film had good gas barrier properties and pinhole resistance, and no gelled material was generated during film formation.

Example 3 The same procedure as in Example 1 was carried out except that the amount of 6X66 copolymer (A) used in Example 2 was changed to 11 parts by weight.

A film was formed.

Example 4 The amount of 6X66 copolymer (A) used in Example 2 was 100M.
The same procedure as Example 1 was carried out except that the parts were changed.

A film was formed.

These results are shown in Table 1, and Example 3 and Example 4
Good results were obtained in both cases.

Example 5 6X12 copolymer (A) [nylon 6
The molar ratio of the constituent units of and the constituent units of nylon 12 (6/
12) is 80720, melting point is 196°C, relative viscosity is 2.5. The amino end group is 10.5X10 equivalents/1. The carboxy terminal group is 2. except that 43 parts by weight of IX 10-5 equivalents/litre were used.

A film was molded in the same manner as in Example 1.

The results are shown in Table 1.

The obtained film had good gas barrier properties and pinhole resistance, and no gelled material was generated even after 10 hours of molding.

Comparative Example 1 A film was molded in the same manner as in Example 1, except that no polyamide was used.

The results are shown in Table 1.

The film obtained as described above has good gas barrier properties, but is hard and has low elongation, so it has poor pinhole resistance.

Comparative Example 2 As a polyamide, the relative viscosity was 2.9. Amino terminal group 4.
6 X 10 equivalents/g. Carboxy end group 5.6×
A film was molded in the same manner as in Example 1, except that 45 parts by weight of nylon 6(B) having a weight of 10 equivalents/y was used.

Comparative Example 3 As a polyamide, 6X66 copolymer (B) [molar ratio of nylon 6 constituent units to nylon 66 constituent units (6
/66) is 85/15, the melting point is 195°C, the relative viscosity is 2.7, and the amino end group is 6.8 × 10 6 equivalents/g.
A film was formed in the same manner as in Example 1, except that 43 parts by weight of 2.4 parts by weight of 0-5 equivalents/g of carboxy end groups were used.

Comparative Example 4 As polyamide, 6X66 copolymer (C) [molar ratio of nylon 6 constituent units to nylon 66 constituent units (6
/66) is 85/15, the melting point is 195°C, the relative viscosity is 2.6, and the amino end group is 8.5 x 10 equivalents/9.
Carboxy end group5. I Xl 0-5 equivalent/y] to 4
A film was molded in the same manner as in Example 1, except that 3 parts by weight were used.

Comparative Example 5 As polyamide, 6/12 copolymer ω) [nylon 6
The molar ratio of the constituent units of and the constituent units of nylon 12 (6/
12) is 80/g0, the melting point is 196°C, the relative viscosity is 2.6.7, the mino end group is 6.7X-10 equivalents/g. The carboxy terminal group is 3. I x 10-5 equivalent/g] to 4
A film was molded in the same manner as in Example 1, except that 5 parts by weight was used.

These results are shown in Table 1, and Comparative Examples 2 and 3°4.5
In both cases, gel was generated 1 to 2 hours after molding, and when molding was continued, it became difficult to form a film.

Comparative Example 6 A film was molded in the same manner as in Example 1, except that the amount of 6X66 copolymer (A) used in Example 2 was changed to 3 parts by weight.

The results are shown in Table 1, and the pinhole resistance of the film obtained as described above was hardly improved.

Comparative Example 7 Same as Example 1 except that the amount of 6X66 copolymer (A) used in Example 2 was changed to 230 parts by weight.

A film was formed.

The results are shown in Table 1, and the film obtained as described above had significantly deteriorated gas barrier properties.

Comparative example day As a polyamide, 6/66 copolymer (D) [molar ratio of the constituent units of nylon 6 and the constituent units of nylon 66 (6
/66) is 85/15, the melting point is 195°C, the relative viscosity is 2.8, and the amino end group is 2.2 x 10 equivalents/9.
Film molding was carried out in the same manner as in Example 1 except that 46 parts by weight of carboxy terminal group 95, 0-5 equivalent/y] was used, but a significant amount of gel was formed during molding, making film formation difficult. became.

Example 6 11! contains 38 moles of repeating units (■) based on ethylene monomer, has a degree of saponification of 99 degrees, an intrinsic viscosity of 0.11 degrees, and a melting point of 173 degrees Celsius! :25 glass fiber to VOH
6/66 copolymer (A
) 43 parts by weight were blended in the form of pellets. Using the mixture, the tensile test piece (ASTM) was put into an injection molding machine.
D-638) and Izotsu impact test pieces (ASTM
D-256) was molded at a cylinder temperature of 250°C.

Even when injection molding was performed for a long time, no gelled material was generated.

The test pieces molded as described above were measured in accordance with ASTM standards, and the impact resistance was improved with a tensile elongation at break of 16% and an izod impact strength (notched) of 9.4 mm/cm. was.

Comparative Example 9 A test piece was injection molded in the same manner as in Example 6, except that no polyamide was used. Measurements were made on this test piece, and the elongation at break was 9%.

Izotsu impact strength (with notch) 6.8Kg・cm /
It was cm.

Comparative Example 10 In place of the 6/66 copolymer (A) in Example 6, 43 parts by weight of the 6/66 copolymer (B) used in Comparative Example 3 was used, and the same procedure as in Example 6 was carried out. , the specimens were injection molded. After 100 shots of molding (approximately 1 hour after the start of molding), a gelatinized substance began to form from the heat, and when molding was continued, molding became difficult due to the gelatinized substance.

Procedural amendment (voluntary) March 2, 1986

Claims (1)

[Claims] Repeating unit based on ethylene monomer (-CH_2--C
100 parts by weight of a saponified copolymer of ethylene and vinyl acetate having 5 to 50 mol% of H_2-) and a degree of saponification of about 80% or more, and a relative viscosity of 2.1 to 3.
．． 5 and 5 to 150 parts by weight of an amino terminal-rich terminal-modified polyamide having 8 x 10 equivalents/g or more of amino terminal groups and 3 x 10 equivalents/g or less of carboxy terminal groups. Characteristic resin composition of saponified ethylene copolymer.