JPH06316661A - Resin composition and laminate - Google Patents

Abstract

PURPOSE:To provide a resin composition useful as a laminate having excellent transparency, gas barrier properties, drop impact resistance, etc., comprising a saponified material of an ethylene-vinyl acetate copolymer and an epoxy group-introduced olefinic polymer in a specific ratio. CONSTITUTION:The composition comprises (A) 60-190wt.% of a saponified material of an ethylene-vinyl acetate copolymer having 20-60mol% ethylene content and >=95% saponification degree of vinyl acetate component and (B) 40-5wt.% of an olefinic polymer into which 700-10,000 epoxy equivalent of epoxy group is introduced.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a resin composition which is excellent in transparency and gas barrier property, and is excellent in flexibility such as drop impact resistance, bending resistance, air bag prevention property, suitability for skin pack packaging, suitability for shrink film and the like. And a laminate comprising at least one layer of the composition.

[0002]

2. Description of the Related Art Saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH) is a thermoplastic resin excellent in transparency, gas barrier property, oil resistance and aroma retention compared with other resins. It is used in various gas barrier films and gas barrier layers of gas barrier containers.
However, a multilayer film that uses EVOH as a gas barrier layer,
Multilayer containers can often have problems due to the high rigidity of EVOH. For example, a multi-layer film or container filled with contents may be easily broken or broken when dropped, a pin hole may occur in the multi-layer film filled with contents due to bending or vibration during transportation, The problems include occurrence of wrinkles during skin pack packaging, insufficient stretchability as a shrink wrapping film, and insufficient shrinkability. Therefore, there has been proposed a method of blending EVOH with another thermoplastic resin to improve these drawbacks. For example, blending EVOH with an ethylene-carboxylic acid vinyl ester copolymer or an ethylene-acrylic acid ester copolymer improves the flex resistance (JP-A-61-220839), and EVOH has an α, β-unsaturated carboxyl group. It is known that blending an acid anhydride-modified ethylene-carboxylic acid vinyl ester copolymer and an ethylene-acrylic acid ester copolymer improves the impact resistance of EVOH (JP-A-61-83035). However, although the bending resistance and impact resistance of EVOH are improved by these methods, the transparency, which is a characteristic of EVOH, is impaired, and it has not been put to practical use in applications requiring transparency.

As a composition having good transparency, a composition comprising EVOH and polyamide can be mentioned. However, the deterioration of the gas barrier property due to blending is large, the thermal stability at the time of molding is poor, and a gel is generated in a short time. However, this composition has not been put to practical use.

Regarding the blending of EVOH with a partially saponified ethylene-vinyl acetate copolymer, the provision of interlayer adhesion with a polyolefin, and the provision of low temperature heat sealability, JP-B-51- 485
1 and JP-A-60-161477.
When molded products such as films are produced by these conventional techniques, there are problems such as lack of flexibility, poor thermal stability, severe moldability due to severe neck-in, and patterns such as stripes and satin. There are drawbacks such as generation on the film surface. Further, JP-A-53-88075 describes that EVOH and an ethylene polymer containing an epoxy group are blended to remarkably improve the adhesiveness to various base materials, particularly metals. In the case of blending a small amount of EVOH as shown in (3), flex resistance and gas barrier property are insufficient.

[0005]

DISCLOSURE OF THE INVENTION The present invention does not have the above-mentioned problems, that is, it has excellent transparency and gas barrier properties, and has drop impact resistance, flex resistance, air bag prevention, skin pack suitability, The present invention provides a resin composition and a laminate having flexibility such as suitability for shrink film.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have found that an ethylene-vinyl acetate copolymer saponified product (A) 60-having an ethylene content of 20 to 60 mol% and a saponification degree of a vinyl acetate component of 95 mol% or more. 95% by weight and epoxy equivalent 700
The resin composition comprising 40 to 5% by weight of the olefin polymer (B) in which 1 to 10,000 epoxy groups are introduced has excellent transparency and gas barrier properties, and has significantly higher flexibility than EVOH alone. It has been found that a laminate containing at least one composition layer is extremely useful as a laminate excellent in drop impact resistance, air bag prevention, skin pack suitability and shrink film suitability, and completed the present invention. It was

The EVOH used in the present invention has an ethylene content of 20 to 60 mol%, preferably 25 to 55 mol%, and a saponification degree of the vinyl acetate component of 95 mol% or more, preferably 98.
It is a resin of mol% or more. When the ethylene content is less than 20 mol%, not only a beautiful molded product such as a film cannot be obtained because it easily gels during melt molding, but also the gas barrier property under high humidity deteriorates. On the other hand, when the ethylene content is higher than 60 mol%, the gas barrier property is greatly deteriorated, which is not preferable. When the degree of saponification is less than 95 mol%, like the case where the ethylene content is less than 20 mol%, gelation is likely to occur during melt molding, and stable operation cannot be performed for a long time. Also,
EVOH melt index (temperature 190 ℃, load 2
Value measured under the condition of 160 g: However, melting point is 190 ° C.
Values near or above 190 ° C were measured under a load of 2160 g at a plurality of temperatures above the melting point. In a semilogarithmic graph, the reciprocal of absolute temperature was plotted on the horizontal axis and the melt index was plotted on the vertical axis, and the value was extrapolated to 190 ° C. Hereinafter, referred to as MI) is more preferably 0.5 to 15 g / 10 minutes.
Further, EVOH referred to in the present invention may be modified with a copolymerization monomer in the range of 5 mol% or less, and as the modifying monomer, propylene, 1-butene, 1-hexene,
4-methyl-1-pentene, acrylic acid ester, methacrylic acid ester, maleic acid, fumaric acid, itaconic acid, higher fatty acid vinyl ester, alkyl vinyl ether, N-vinyl pyrrolidone, N-normal butoxymethyl acrylamide, vinyl trimethoxysilane, Examples thereof include vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, N- (2-dimethylaminoethyl) methacrylamides or quaternary products thereof, and N-vinylimidazole or quaternary products thereof.

The olefin-based polymer introduced with an epoxy group used in the present invention is a random copolymer of an olefin monomer and an epoxy group-containing ethylenically unsaturated monomer, or an olefin-based polymer with an epoxy resin. It is a modified olefin polymer obtained by graft-polymerizing a group-containing ethylenically unsaturated monomer with an initiator such as peroxide, heat, light, or ionizing radiation. Examples of the epoxy group-containing ethylenically unsaturated monomer include glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, vinyl glycidyl ether, hydroxyalkyl acrylate or hydroxyl methacrylate glycidyl ether. The modification amount is 700 to 10,000, more preferably 1,000 to 10,000 in terms of epoxy equivalent.
It is 6000. Here, the epoxy equivalent is represented by g of a resin containing 1 g equivalent of an epoxy group. When the epoxy equivalent is less than 700, there are disadvantages such as vigorous thickening, gelation and deterioration of moldability.
If it exceeds 0, the transparency and mechanical properties of the composition may be poor, possibly due to poor compatibility with EVOH, which is not preferable. Further, examples of the olefin monomer include ethylene, propylene, butylene and the like, and examples of the olefin polymer include polyethylene (low density, medium density, high density,
Linear low density), polypropylene, polybutylene and the like. Particularly preferably, low density polyethylene is used. The MI of the olefin-based polymer introduced with an epoxy group in the present invention is not particularly limited, but is 0.1 to 0.1.
50 g / 10 minutes is preferable, more preferably 0.5 to 15
g / 10 minutes.

The resin composition of the present invention is a mixture of EVOH (A) and an epoxy group-introduced olefin polymer (B), and the mixing ratio thereof is A / B = 60 to 95 /
40 to 5 (weight ratio), more preferably A / B = 70
˜90 / 30 to 10 (weight ratio). If the blending amount of the olefin polymer having an epoxy group introduced therein is less than 5% by weight based on the composition, the drop impact resistance and the flex resistance are poor. On the other hand, when it exceeds 40% by weight, not only the transparency is poor, but also the gas barrier property is poor.

The EVOH and the epoxy group-introduced olefin-based polymer can be mixed by using a Banbury mixer, a single or twin screw extruder, a Brabender plast mill, etc. It may be supplied to a molding machine and kneaded by a molding machine to be molded.
Further, when kneading these, a plasticizer, a lubricant, an antioxidant, a colorant, various resins and the like may be added within a range that does not impair the effects of the present invention.

The resin composition of the present invention is preferably used in a laminate. At this time, the resin composition of the present invention is an intermediate layer,
It can be used as either the outermost layer or the innermost layer.
The resin to be laminated with the resin composition of the present invention is not particularly limited, but a resin having good transparency is generally preferable, and examples thereof include low density polyethylene, linear low density polyethylene, polypropylene, and ethylene-propylene copolymer. Coalescing,
Polyolefin such as polybutene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, copolymer mainly composed of olefin such as ionomer, polystyrene, polyamide, polyethylene terephthalate,
Examples include polycarbonate, polyvinyl chloride, and the like, or a mixture thereof. Of these, particularly preferably used are low density polyethylene, linear low density polyethylene, polypropylene, ethylene-propylene copolymer,
The ethylene-vinyl acetate copolymer is a homopolymer or a mixture thereof.

When the interlayer adhesion between these resins and the resin composition of the present invention is not sufficient, it is preferable to provide an adhesive resin layer. The adhesive resin is not particularly limited as long as it does not cause delamination at a practical stage, and is not particularly limited, and an unsaturated carboxylic acid or an anhydride thereof is used as an olefin polymer (for example, low density polyethylene, linear low density Polyolefins such as polyethylene, polypropylene and polybutylene, copolymers of olefins and unsaturated monomers copolymerizable therewith (vinyl esters, unsaturated carboxylic acid esters, etc.), for example ethylene-vinyl acetate copolymers, ethylene- A modified olefin-based polymer containing a carboxyl group, which is obtained by chemically bonding (for example, by an addition reaction or a graft reaction) to the acrylic acid ethyl ester copolymer}. Specifically, one or a mixture of two or more selected from maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer and the like. Are preferred. EVOH, for example, the resin composition of the present invention may be mixed with these adhesive resins within a range that does not impair the effects of the present invention. The resin composition of the present invention, as a laminate, a film, a sheet,
It can be molded into a tube, a bottle and the like, and the thickness constitution of each layer is not particularly limited, but from the viewpoint of transparency, the resin composition layer of the present invention is preferably used in a thickness of 300 μm or less, and more preferably Is 200 μ or less.

The method for laminating the resin composition of the present invention is not particularly limited, and examples thereof include a coextrusion method, an extrusion lamination method and a dry lamination method. Particularly, according to the coextrusion method, the resin composition of the present invention can be obtained. It is preferable because the characteristics can be exhibited.

The laminate thus obtained is suitable for containers having excellent drop impact resistance, tubes having excellent air bag prevention, bag-in-box having excellent flex resistance, suitability for skin pack, and suitability for shrink film. It can be used as an excellent film or the like.

[0015]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. "Parts" or "%" in the examples are by weight unless otherwise specified. Example 1 Melt index (MI) measured according to ASTM D1238 65T under the conditions of ethylene content of 32 mol%, saponification degree of vinyl acetate component of 99.4 mol%, 190 ° C. and 2160 g load was 4.0 g / 10 minutes EVOH
70 parts and epoxy equivalent of 1050, MI of 4.3 g /
10 minutes of 30 parts of glycidyl methacrylate random copolymer modified low-density polyethylene was blended and pelletized at a temperature of 220 ° C. by a 30φ different-direction biaxial extruder. Then, using these pellets, an extruder temperature of 180 to 220 ° C. was measured by a film forming machine consisting of an extruder of 40φ and a T die.
The film was formed under the condition of T-die temperature of 215 ° C. to obtain a film having a thickness of 25 μm. The film was evaluated for film surface, moldability, haze, loop stiffness, flex resistance, Young's modulus, and oxygen gas transmission rate (OTR). The evaluation of the film surface was performed by visually scoring streaks, satin and spots in five grades A to E shown in Table 1.

[0016]

[Table 1]

The haze was measured using a Poic integrating sphere type light transmittance meter manufactured by Nippon Seimitsu Optical Co., Ltd. The loop stayness is the repulsive force when a film with a width of 15 mm is bent into a loop with a length of 60 mm by a loop stay funnel tester manufactured by Toyo Seiki Co., Ltd., and the loop diameter is compressed to 20 mm at 20 ° C. and 65% RH. It was measured under the conditions of. The loop stiffness is important as a measure of the air bag prevention property, and it is considered that a composition having a small loop stiffness has a good air bag prevention property.

The flex resistance was evaluated by using a Gelbo flex tester manufactured by Rigaku Kogyo Co., Ltd., and a film of 12 inches × 8 inches was formed into a cylindrical shape having a diameter of 3.5 inches. Spacing of 7 inches, gripping distance of 1 inch at maximum bending, a twist of 440 degrees was added at the first 3.5 inches of the stroke, and 2.5 inches after that, a reciprocating reciprocating motion of linear horizontal motion was performed. 300 ° C. and 400 at 20 ° C. and 65% RH conditions
The number of pinholes was determined for the film after repeating the number of times.

Young's modulus is ASTM D-882-67
The measurement was performed under the conditions of 20 ° C. and 65% RH according to the above. Young's modulus is important in relation to suitability for skin pack and shrink film. That is, it can be said that a resin composition having a low Young's modulus, which can be stretched with a smaller force, is suitable for skin pack packaging and shrink film packaging including a stretching step.

The oxygen gas transmission rate (OTR) is measured by Mo
OX-TRAN 10 manufactured by Dern Control
-50A was used, and it measured on 20 degreeC and 65% RH conditions. The evaluation results are shown in Table 2. The resin composition has good film surface and transparency, and has excellent loop stability, flex resistance, Young's modulus and other flexibility and gas barrier properties. There is.

Examples 2 to 3 Using various EVOH and various epoxy group-containing olefin polymers, films having a thickness of 25 μm were prepared in the same manner as in Example 1 and various evaluations were performed. The results are shown in Tables 2 and 3. Here, the various epoxy group-containing olefin-based polymers used in each example are shown below. That is, in Example 2, the epoxy equivalent was 2900 and the MI was 4.1.
G / 10 min glycidyl methacrylate random copolymer modified low density polyethylene was used. In Example 3, glycidyl acrylate copolymer-modified low density polyethylene having an epoxy equivalent of 830 and an MI of 2.0 g / 10 min was used. In each of Examples 2 to 3, both the film surface and the transparency are good, and the loop stiffness, the flexibility represented by Young's modulus and the gas barrier property are excellent.

Comparative Example 1 In Example 1, the ethylene content was 32 mol%, the saponification degree of the vinyl acetate component was 99.4 mol%, and the MI was 4.0 g.
/ 10 minutes EVOH 70 parts and epoxy equivalent 1050
In place of the resin composition consisting of 30 parts of glycidyl methacrylate random copolymer modified low density polyethylene having an MI of 4.3 g / 10 min, the EVOH alone has a thickness of 25 μm.
Table 2 and Table 3 show the results of various evaluations of the above film. Although the film surface, transparency and gas barrier property are good, the Young's modulus is high and the flexibility is poor, so that the flex resistance is poor.

Comparative Examples 2 to 8 Various EVOH and various epoxy group-containing olefin polymers were used to prepare 25 μm-thick films in the same manner as in Example 1, and various evaluations were performed. The results are shown in Tables 2 and 3. The epoxy group-containing olefin polymer used in Comparative Examples 2, 3, and 7 is the same as that described in Example 1. The epoxy group-containing olefin polymer used in Comparative Example 8 is the same as that described in Example 4. In Comparative Example 3, 1 part of glycidyl acrylate and 0.5 part of dicumyl peroxide were added to 100 parts of ethylene-vinyl acetate copolymer having an ethylene content of 88% by weight and kneaded in a Brabender plastomill at 150 ° C. for 80 minutes. A glycidyl acrylate-grafted ethylene-vinyl acetate copolymer having an epoxy equivalent of 12000 and an MI of 1.9 g / 10 min was used. In Comparative Example 5, glycidyl acrylate copolymerization modified low density polyethylene having an epoxy equivalent of 600 and an MI of 1.1 g / 10 min was used.

Similar to Comparative Example 1, Comparative Example 2 has good film surface, transparency, and gas barrier property, but has a high Young's modulus and poor flexibility, and therefore has poor bending resistance. This is because the compounding ratio of the epoxy group-containing olefin polymer is 3
This is probably because the percentage is too small. In Comparative Example 3, when the compounding ratio of the epoxy group-containing olefin polymer is as high as 50%, the flexibility is high, but the gas barrier property is extremely poor.

In Comparative Example 4, although the flexibility is high, the dispersion state of the epoxy group-containing olefin polymer is poor and the transparency is poor, probably because the epoxy equivalent is low. Comparative Examples 5-7
Has many spots and the film surface is extremely poor. Comparative Example 8
When EVOH has a high ethylene content of 65 mol%, the EVOH has good flexibility, but is not practical because of its low gas barrier property.

[0026]

[Table 2]

[0027]

[Table 3]

Example 4 EVOH having an ethylene content of 44 mol%, a saponification degree of a vinyl acetate component of 99.1 mol%, and an MI of 5.5 g / 10 min.
70 parts and epoxy equivalent of 1050, MI of 4.3 g /
A 15 μm-thick intermediate layer consisting of 10 minutes of 30 parts of glycidyl methacrylate random copolymer modified low-density polyethylene, and 4-methyl-1 having a thickness of 30 μm on each side of the intermediate layer.
-Pentene as a copolymerization component, having 3.2 mol% of the copolymerization component and having a surface layer made of linear low-density polyethylene having an MI of 2.1 g / 10 min, and acetic acid having a thickness of 5 µ between the layers. Extrusion of three laminated films of 85 μm in total, which were arranged through an adhesive resin layer made of a maleic anhydride-modified ethylene-vinyl acetate copolymer having a vinyl content of 20% by weight and a maleic anhydride content of 0.5% by weight. Was obtained by a co-extrusion method using a multi-layer die head for three types of five layers. As the resin composition used for the intermediate layer, pellets preliminarily blended by an extruder were used. The obtained laminated film was subjected to gelbo flex test until the occurrence of pinholes in the laminated film, and the oxygen gas permeation amount at each stage until the occurrence of pinholes was 20 ° C. and 65% RH. It was measured under the conditions. The samples of flexural fatigue at each stage were formed into a 12 inch × 8 inch flat surface, and the measurement was made at the center thereof. The measurement results are shown in Table 4. In the bending fatigue test process until the pinhole was generated, there was almost no change in the oxygen gas permeation amount. In addition, the occurrence of pinholes was not observed until the bending fatigue test was repeated 7,000 times,
After 100 round trips, it was confirmed that one pinhole had already occurred at the time when the presence or absence of the pinhole was inspected.
Moreover, delamination between the layers was not observed at all. The haze of the film was 5%, the transparency was good, and no stripes or satin was observed.

Comparative Example 9 In Example 4, the intermediate layer had an ethylene content of 44 mol%, a vinyl acetate component saponification degree of 99.1 mol%, and MI.
Was used in the same manner as in Example 4 except that EVOH alone was used at 5.5 g / 10 min, and various evaluations were performed. The results are shown in Table 4. The film has poor flexibility and poor bending fatigue resistance.

[0030]

[Table 4]

Example 5 EVOH having an ethylene content of 44 mol%, a saponification degree of a vinyl acetate component of 99.1 mol%, and an MI of 5.5 g / 10 min.
70 parts and epoxy equivalent is 2900, MI is 4.1 g /
An intermediate layer having an average thickness of 50 μm consisting of 30 parts of glycidyl methacrylate random copolymer modified low density polyethylene for 10 minutes, and 70 parts of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5% by weight on both sides of the intermediate layer, maleic anhydride. An average thickness of all layers consisting of 30 parts of maleic anhydride-modified ethylene-vinyl acetate copolymer having an acid content of 0.5% by weight of 300 μm each
A container having inner and outer layers (10 l in volume) was obtained by coextrusion / direct blow molding using two extruders and a two-layer, three-layer multi-layer die head. The resin composition used for the intermediate layer here was pellets blended in advance with an extruder. Fill this container with 10 l of water and
When dropped three times from the height of m, the bag did not break and showed good impact resistance.

Comparative Example 10 In Example 5, the ethylene content was 44 mol%, the saponification degree of the vinyl acetate component was 99.1 mol%, and the MI was 5.5 g.
/ 10 minutes EVOH 70 parts and epoxy equivalent 18000
Then, a multilayer direct blow container was molded in the same manner as in Example 5, except that the resin composition for the intermediate layer was a resin composition consisting of 30 parts of glycidyl methacrylate copolymerization-modified low-density polyethylene having MI of 3.5 g / 10 min. Then, the same drop test was performed. The container broke in the first drop and had poor impact resistance.

Example 6 EVOH having an ethylene content of 44 mol%, a saponification degree of a vinyl acetate component of 99.1 mol%, and an MI of 5.5 g / 10 min.
70 parts and epoxy equivalent is 2900, MI is 4.1 / 1
An intermediate layer having an average thickness of 20 μm consisting of 0 part of glycidyl methacrylate random copolymer-modified low-density polyethylene of 30 parts, and an average thickness of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 8% by weight on both sides of the intermediate layer. 150
An adhesive resin layer comprising a maleic anhydride-modified ethylene-vinyl acetate copolymer having a vinyl acetate content of 20% by weight and a maleic anhydride content of 0.5% by weight and having a surface layer of .mu. A laminated tube having an average thickness of 350 μm for all layers was obtained by coextrusion / direct blow molding using three extruders and a three-layer five-layer multilayer die head. The resin composition used for the intermediate layer here was pellets blended in advance with an extruder. The repulsive force was 700 mg when the center of the body of the obtained tube was cut to a width of 15 mm and compressed by a loop stay funnel tester for 10 mm.

Comparative Example 11 In Example 6, the intermediate layer had an ethylene content of 44 mol%, a vinyl acetate component saponification degree of 99.1 mol%, and MI.
When EVOH of 5.5 g / 10 min was used alone, a multilayer tube was molded in the same manner as in Example 6, and a loop stiffness test was conducted. The repulsive force was 1500 mg.
Met.

[0035]

EFFECT OF THE INVENTION The resin composition of the present invention has excellent transparency and gas barrier properties, and has significantly higher flexibility than EVOH alone. A laminate containing at least one layer of the resin composition is
It is extremely useful as a laminate having excellent drop impact resistance, air bag prevention, skin pack suitability, and shrink film suitability.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location (C08L 29/04 23:26)

Claims (2)

[Claims] 1. An ethylene-vinyl acetate copolymer saponified product (A) having an ethylene content of 20 to 60 mol% and a saponification degree of a vinyl acetate component of 95 mol% or more, and an epoxy equivalent of 700 to 700%. A resin composition comprising 40 to 5% by weight of an olefin polymer (B) having 10000 epoxy groups introduced therein. 2. A laminate comprising at least one resin composition layer according to claim 1.