JPS62252446A - Resin composition containing saponified ethylene copolymer - Google Patents

Abstract

PURPOSE:To provide the title compsn. which gives a film having excellent gas barrier properties, impact resistance, etc., by blending a highly saponified ethylene/vinyl acetate copolymer with a polyamide having terminals modified with a monoamine. CONSTITUTION:Ethylene monomer is copolymerized with vinyl acetate monomer. The resulting copolymer is saponified to obtain a saponified ethylene/vinyl acetate copolymer composed of 5-50mol% of a repeating unit (-CH2-CH2-) originating from the ethylene monomer and having a degree of saponification of not lower than 80%. 100pts.wt. said saponified copolymer is mixed with 5-150pts.wt. polyamide (e.g., nylon 6/12 copolymer) having a terminal amino group content of lower than 8X10<-5> equivalents/g, a terminal carboxyl group content of not higher than 3X10<-5> equivalents/g, a relative viscosity of 2.1-3.5 and terminals modified with a monoamine to obtain the titled resin compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Applicability] The present invention relates to a resin composition containing a saponified ethylene copolymer. Specifically, from the resin composition of the present invention, which is a resin composition in which a specific polyamide is blended in a specific ratio to a saponified product in which an ethylene-vinyl acetate copolymer is highly saponified. Films or containers formed by extrusion have excellent gas barrier properties and impact resistance (pinhole resistance), and can be particularly suitably used as food packaging films or containers. Moreover, molded articles molded from the resin composition of the present invention by injection molding 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] In general, saponified ethylene-vinyl acetate copolymers (hereinafter abbreviated as EVOH) have extremely good gas barrier properties, so they are required to have a low oxygen gas permeation rate. Used as a material to form food packaging films or containers. In addition, EVOH blended with glass fiber has high rigidity and heat resistance, so metal parts (
It is used in various functional parts as an alternative to AJI die casting, Zn die casting, etc.).

However, this EVOH has the drawback that its molded product is hard and brittle, and this limits its use. For example, when used as a film or sheet for food packaging, the film tends to tear or form pinholes during packaging, moving, and transporting the packaged product, and its excellent gas barrier properties cannot be fully maintained. I am unable to make the most of it. Furthermore, this injection molded product of EVOH is
In particular, problems such as cracks often occur immediately after molding or when used at low temperatures.

In general, the physical properties and moldability of EVOH change depending on the ethylene content and degree of saponification. However, the gas barrier properties, which are the characteristics of EVOH, deteriorate.

There were strong expectations for a new technology that would improve impact resistance without significantly compromising rigidity or heat resistance.

As a means to improve these EVOH problems,
Methods of using resin compositions in which EVOH is mixed with various polyamides are disclosed, for example, in Japanese Patent Publication No. 44-24277, Japanese Patent Publication No. 48-22833, and Japanese Patent Application Laid-open No. 1977-121.
This method is disclosed in JP-A-347, JP-A-54-78749, JP-A-54-78750, JP-A-55-34956, and the like.

In the above method, since EVOH and polyamide are mutually compatible, if polyamide is blended with EVOH and mixed, the polyamide acts to improve the impact resistance, and the original superiority of EVOH is improved. This does not significantly impair gas barrier properties, rigidity, and heat resistance.

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

In other words, when EVOH and polyamide are mixed in a molten state at high temperatures and then molded, a chemical reaction occurs between the two, increasing the melt viscosity and eventually gelling, making molding impossible. It is.

This problem of gelation becomes more pronounced as the molding temperature is higher, so methods have been proposed in which various copolyamides with low melting points are used as polyamides for the purpose of molding at lower temperatures. Such methods include, for example, JP-A-54-78749 and JP-A-54-78750.
For example, methods disclosed in Japanese Patent Application Laid-open No. 55-34956 and the like can be mentioned.

However, even with these methods, it is difficult to completely prevent gelation, and EVOH
There is a strong need for a practical method to improve the impact resistance of.

[Requirements and effects of the present invention] As a result of intensive research to improve the impact resistance of EVOH, the present inventors have found that a polyamide modified with a specific end group is mixed with a specific EVOH. The resin composition is
It was discovered that gelation does not easily occur during molding, and that the gas barrier properties, rigidity, heat resistance, etc. of the molded product are not impaired, and that the pinhole resistance (impact resistance) can be improved, and the present invention was completed. It has arrived.

That is, the resin composition of the present invention comprises (a) a repeating unit based on ethylene monomer (-CH2-
100 parts by weight of a saponified ethylene-vinyl acetate copolymer having 5 to 50 mol% of CHz-) and a degree of saponification of 80% or more; and (b) an amide 7 group terminal concentration of 8X10- 5 equivalents/g and the carboxyl end group concentration is 3×10-s equivalents/g.
g or less, and a relative viscosity of 2.1 to 3.5, and 5 to 150 parts by weight of a polyamide terminal-modified with a monoamine.

The resin composition of the present invention: (a) during molding of films, containers, injection molded products, etc.
(b) The molded product has sufficient gas barrier properties, rigidity, and heat resistance, and has improved pinpole resistance (impact resistance). Therefore, it can be suitably used as packaging material or functional parts.

[Detailed explanation of each requirement of the present invention] The saponified product of the copolymer of ethylene and vinyl acetate (EVOH) used in the present invention is a repeating unit (-CH2-CH2-) based on ethylene monomer (hereinafter referred to as 5 to 50 mol%, preferably 10 to 45 mol%, particularly preferably 15 to 45 mol%, based on the total amount of the polymer
The saponification degree is about 80% or more, preferably 90% or more, particularly preferably 95% or more.

This EVO)I is produced by saponifying an ethylene-vinyl acetate copolymer obtained by polymerizing ethylene monomer and vinyl acetate monomer by a known method, and the repeating unit process based on ethylene monomer is If it is less than 5 mol % based on the saponified product, the moldability of the resin composition obtained using such a saponified product will be deteriorated, so it is not suitable.

On the other hand, if the repeating unit I based on ethylene monomer is
If the amount is more than 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 the present invention, the degree of polymerization of EVOH is not particularly limited, but it is preferable to have an intrinsic viscosity of 0.07 to 0.17 (measured at 30'C! in 15% by weight hydrated phenol).

Polyamides used in the present invention include terminally modified polyamides such as nylon 6, nylon 610, and nylon 12 (hereinafter referred to as "terminally modified polyamides").
Copolymers mainly composed of nylon 6, such as nylon 6766 copolymer, nylon 6/12 copolymer, nylon 66 Terminal-modified polyamides based on /610/6 copolymers and the like are preferred.

When such a polyamide is used as a component of the resin composition of the present invention, the molecular chain terminal thereof is modified with an amine, and the amino end group concentration is less than 8×10−5 equivalents/g. and carboxyl end group concentration is 3X
It is necessary that it is 10-5 equivalent/g or less. Polyamides that do not satisfy these terminal group concentration conditions are EV
When blended with OH, the melt viscosity during molding increases, making continuous molding difficult over a long period of time. Monoamines used to modify the terminals of polyamide include:
Examples include aliphatic monoamines such as laurylamine and aromatic monoamines such as methylbenzylamine. By adding these during the polymerization reaction for producing polyamide, the terminals can be modified.

Also, such polyamides, in addition to the above requirements,
Its relative viscosity is 2.1-3.5, preferably 2.2-3
．． It is necessary to be 2. Products with too high a relative viscosity (high degree of polymerization) are difficult to manufacture, and those with a very low relative viscosity (low degree of polymerization) will not achieve the desired pin resistance when blended with EVOH. It is not possible to achieve improvement in hole properties (#impact properties).

In the resin composition of the present invention, the blending ratio of EVOH and polyamide is 5 to 150 parts by weight, preferably 10 to 100 parts by weight, per 100 parts by weight of EVOH.

In the resin composition of the present invention, if the blending ratio of polyamide to EVOH is too small, the mechanical properties such as pinhole resistance (impact resistance) of the molded product formed from such a resin composition may be deteriorated. This is not appropriate as it cannot be improved. Furthermore, if the blending ratio of polyamide to EVOR is too large, the gas barrier properties of the molded product formed from such a resin composition may deteriorate.
It is not suitable because the rigidity etc. will be insufficient.

Other components such as pigments, heat stabilizers, antioxidants, weathering agents, crystallization promoters, lubricants, fillers, plasticizers, etc. may be added in appropriate amounts to the resin composition of the present invention, if necessary. You can also do that. In particular, those filled with glass fiber have high rigidity, creep resistance, and heat resistance, and are therefore effective when used as injection molded products.

The resin composition of the present invention can be prepared, for example, by uniformly mixing EVOH and polyamide in the form of pellets or powder, then melting and kneading them in an extrusion kneader to form pellets, and using the pellets for molding. , or by uniformly mixing pellets, powder, etc. of the saponified product and polyamide,
A suitable method is to directly supply the mixture to a film molding machine or an injection molding machine, and mold the mixture while kneading it in the molding machine.

In order to make films, containers, injection molded products, etc. from the resin composition of the present invention, ordinary extrusion molding methods and injection molding methods can be applied. Stable continuous molding is possible.

Films, sheets, etc. made of the resin composition of the present invention are
In addition to having excellent gas barrier properties and pinhole resistance,
It also maintains transparency and chemical resistance, making it highly useful. Furthermore, injection molded products made from the resin composition of the present invention have excellent rigidity, heat resistance, and impact resistance, as well as excellent wear properties and chemical resistance, and can be used as engineering plastics for various functional parts. Can be used.

[Example] The resin composition of the present invention will be explained in more detail below with reference to Examples and Comparative Examples. The physical properties of the film in each Example or Comparative Example were measured according to the method described below.

(1) Oxygen permeability: Oxygen gas permeability measurement device (manufactured by Modern Control Co., Ltd.) under absolute dry conditions of 20°C1.

0XYTRAN-100 type) was used for measurement.

(2) Pinhole resistance A tensile test in the pulling direction (M, D,) was conducted in accordance with ASTM D-882 at 23° C. in an absolutely dry state. The tensile modulus and elongation were used as measures of pinhole resistance. That is, in the above test, the lower the tensile modulus,
It is evaluated that the higher the elongation rate, the better the pinhole resistance.

(3) Thickening and gelling properties■ EVOH and terminally modified polyamide are melt-kneaded in a single-screw extruder to form pellets of the resin composition of the present invention, and the pellets are sealed in nitrogen gas and transferred into a glass tube. It was enclosed in. Thereafter, the pellets were melted and heated in a 250°C oil bath for a predetermined period of time (approximately 6 hours), and the melt viscosity of the pellets was measured using a capillary rheometer under the following conditions.

Measurement temperature: 250°C Measurement shear rate: 100 sec' Ratio between the melt viscosity η of the untreated oil bath material measured in this way and the viscosity η after heat treatment for 6 hours (η6/η
) was taken as the gelation rate.

■For gelation behavior during film molding, molding temperature 2
After extrusion molding at 50°C, the evaluation was based on the time until a gelled product was generated.

The thickening and gelling properties were evaluated using the above (1) and (2).

(4) In addition, the method for measuring relative viscosity in the following Examples and Comparative Examples is in accordance with JIS K-6810, and the method for measuring amine end group concentration and carboxyl end group concentration is in accordance with Waltz, J.E., Anal Ohem.

448 (1947). For amine end groups, the sample was dissolved in a phenol/methanol solution and m
- Determined by neutralization titration with hydrochloric acid, and carboxyl end groups are determined by dissolving the sample in hot benzyl alcohol.
The 2-enol phthalein indicator was determined by neutralization titration with an aqueous m-sodium hydroxide solution.

Example 1 Based on ethylene monomer, containing 38 mol% of anti-ff units I, having a degree of saponification of 99%, an intrinsic viscosity of 0.14 and a melting point of 173°C, 100 parts by weight of 6EVOH, and nylon 6 The molar ratio (6/66) of the constituent units of and the constituent units of nylon 66 is 85/15, and the melting point is 195 ° C.
1 relative viscosity is 2.6, carboxyl end group concentration is 2.2
×10-5 equivalents/g and amine end group concentration of 7.5XI
43 parts by weight of a laurylamine-terminated nylon 6/nylon 66 copolymer (hereinafter referred to as "polyamide A") having an O-5 equivalent/g were mixed until uniform pellets were obtained. Then, this mixture was extruded into an extruder (T-gui extruder, screw diameter was 40 mm).
mm) and melt-extruded at 250°C to form a film. The film was then cooled and solidified on a casting drum with a surface temperature of 70"C to obtain a film having a thickness of about 501 L. The physical properties of this film were evaluated using the method described above. The results are shown in Table 1.

Example 2 Instead of polyamide A, the molar ratio of the structural units of nylon 6 and the structural units of nylon 66 (6/66) was 85/
15, melting point 195°C, relative viscosity 3.2, carboxyl end group concentration 2.6X10-5 equivalents/g and amino end group concentration 5.3X10-5 equivalents/g, methylbenzyl terminated. Amine-modified nylon 6/nylon 66 copolymer (hereinafter referred to as "polyamide B")
A film was molded in the same manner as in Example 1 except that 43 parts by weight was used. The same tests as in Example 1 were conducted on this film. The results are shown in Table 1.

Examples 3 and 4 Films were molded in the same manner as in Example 1, except that the amount of polyamide A used was 11 parts by weight in Example 3 and 100 parts by weight in Example 4. The same tests as in Example 1 were conducted on these films. The results are shown in Table 1.

Example 5 Instead of polyamide A, the molar ratio (6/12) of the constituent units of nylon 6 and the constituent units of nylon 12 was 80/2.
laurylamine with a melting point of 196°C, a relative viscosity of 2.8, a carboxyl end group concentration of 1.9XIO-5 equivalents/g and an amino end group concentration of 5.9/10-5 equivalents/g. Nylon 6/Nylon 1 whose ends are modified with
A film was molded in the same manner as in Example 1 except that 43 parts by weight of the 2 copolymer was used. The same tests as in Example 1 were conducted on this film. The results are shown in Table 1.

Example 6 Instead of polyamide A, the molar ratio (6/12) of the constituent units of nylon 6 and the constituent units of nylon 12 was 60/40.
, a melting point of 150 to 160°C, a relative viscosity of 2.5,
The carboxyl end group concentration is 2.0 x 104 equivalents/g and the amino end group concentration is 5.8 x 104 equivalents/g.
A film was formed in the same manner as in Example 1, except that 43 parts by weight of a nylon 6/nylon 66 copolymer terminal-modified with laurylamine was used. The same tests as in Example 1 were conducted on this film.

The results are shown in Table 1.

As is clear from the table, the films obtained in Examples 1 to 6 all had good gas barrier properties and significantly improved pinhole resistance. Moreover, no gelled material was generated even after 10 hours had passed after molding.

Comparative Example 1 A film was formed in the same manner as in Example 1, except that no polyamide was used, and its physical properties were measured. The results are shown in Table 1.

Comparative example 2 Nylon 6 structural unit and nylon 66 as polyamide
The molar ratio (6/66) with the structural unit of A film was formed in the same manner as in Example 1, except that a non-terminated nylon 6/nylon 66 copolymer having a concentration of 4.7×to-5 equivalents/g was used, and its physical properties were measured. did. The results are shown in Table 1.

Comparative example 3 Nylon 6 structural unit and nylon 12 as polyamide
The molar ratio (6/12) with the structural unit of The concentration is 5.6 x 10-5 equivalents/g. A film was formed in the same manner as in Example 1, except that 43 parts by weight of a nylon 6/nylon 12 copolymer terminal-modified with laurylamine was used, and its physical properties were measured. The results are shown in Table 1.

Comparative example 4 Nylon 6 structural unit and nylon 12 as polyamide
The molar ratio (6/12) with the structural unit of A film was formed in the same manner as in Example 1, except that 43 parts by weight of a stearic acid-terminated nylon 6/nylon 12 copolymer having a concentration of 2.4 x 10 -5 equivalents/g was used. and measured its physical properties. The results are shown in Table 1.

Comparative Examples 5 and 6 Films were formed in the same manner as in Example 1, except that the amount of polyamide A used was 3 parts by weight in Comparative Example 5 and 230 parts by weight in Comparative Example 6, and its physical properties were measured. . The results are shown in the table.

As is clear from the table, the films obtained in Comparative Examples 1 to 6 had unsatisfactory physical properties as shown below.

That is, the films of Comparative Examples 1 to 5 showed good gas barrier properties, but the film of Comparative Example 6 showed good values.
It was greatly inferior. Regarding pinhole resistance, the films of Comparative Examples 1 and 5 were very poor because they were hard and had little elongation. Regarding the generation of gelled substances during molding, in the film of Comparative Example 2, gelled substances were generated 1 hour after molding, and in the film of Comparative Example 3, gelled substances were generated 2 hours after molding. Furthermore, in the film of Comparative Example 4, it was difficult to form a film because a gelled product was generated immediately after molding.

Example 7 100 parts by weight of EVOH containing 138 mol% of repeating units based on ethylene monomer, having a degree of saponification of 99%, an intrinsic viscosity of 0.11 and a melting point of 173° C. and 25% glass fiber. Then, 43 parts by weight of polyamide A was blended in the form of a pellet. Using the mixture, tensile test pieces (prepared according to ASTM D-638) and Izot impact test pieces (ASTM D-638) were prepared using an injection molding machine.
256) at a cylinder temperature of 250°C.
It was molded with. Even when injection molding was performed for a long time, no gelled material was generated. The test pieces molded as described above were measured according to ASTM standards, and the tensile elongation at break was 14%, and the isot impact strength (notched) was 9.2 kg.
cm/am and impact resistance were improved.

Comparative Example 7 A test piece was injection molded in the same manner as in Example 6, except that no polyamide was used. Measurements were performed on this test piece, and the elongation at break was 9%, and the Izot impact strength (with notches) was 6.8 kg·cm/cm.

Comparative Example 8 A test piece was injection molded in the same manner as in Example 7, except that 43 parts by weight of the 6/66 copolymer used in Comparative Example 2 was used instead of polyamide A in Example 7.

Gelled products began to form around 100 shots of molding (approximately 1 hour after the start of molding), and as molding was continued, molding became difficult due to the gelled products.

2 procedural amendments from the bottom line of page 14 of the specification and from the bottom of page 15 July 4, 1986

Claims (1)

[Scope of Claims] (a) An ethylene-vinyl acetate copolymer containing 5 to 50 mol% of repeating units (-CH_2-CH_2-) based on ethylene monomer and having a saponification degree of 80% or more. 100 parts by weight of a saponified product of
5 equivalents/g or less and a relative viscosity of 2.1 to 3.5, monoamine-terminated polyamide 5 to
150 parts by weight of a saponified ethylene-vinyl acetate copolymer-containing resin composition.