JP2766250B2 - Laminate and its use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is excellent in transparency and gas barrier properties, flexibility such as drop impact resistance, bending resistance, air bag prevention, skin pack packaging suitability, shrink film suitability, and interlayer adhesion. And a use thereof.

[0002]

2. Description of the Related Art Saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH) is a thermoplastic resin having extremely excellent transparency, gas barrier properties, oil resistance and fragrance retention properties as compared with other resins. It is used in various gas barrier films and gas barrier layers of gas barrier containers.
However, a multilayer film using EVOH as a gas barrier layer,
Multi-layer containers often have problems due to the high rigidity of EVOH. For example, a multilayer film or container filled with contents may easily break or break when dropped, pinholes may occur in the multilayer film filled with contents due to bending or vibration during transportation, and airbags for multilayer tubes may be damaged. Problems such as generation, wrinkling during packaging of the skin pack, stretchability as a film for shrink packaging, and insufficient shrinkage.

Therefore, a method has been proposed in which another thermoplastic resin is blended with EVOH to improve these disadvantages. For example, when EVOH is blended with an ethylene-carboxylate vinyl ester copolymer or an ethylene-acrylate ester copolymer, the flex resistance is improved (Japanese Patent Application Laid-Open No.
1-220839) or blending EVOH with an α, β-unsaturated carboxylic anhydride-modified ethylene-carboxylate vinyl ester copolymer or ethylene-acrylate ester copolymer improves the impact resistance of EVOH. (JP-A-61-83035) is known. However, these methods improve the bending resistance and impact resistance of EVOH, but impair the transparency characteristic of EVOH, and have not been put to practical use in applications requiring transparency.

[0004] As a composition having good transparency, a composition comprising EVOH and polyamide can be mentioned. However, the gas barrier property is greatly reduced by blending, 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.

[0005] Further, the blending of EVOH with a partially saponified ethylene-vinyl acetate copolymer, the provision of interlayer adhesion to polyolefins, and the provision of low-temperature heat-sealing properties are described in Japanese Patent Publication No. 485
1 and JP-A-60-161377,
Fabricating molded products such as films with these conventional techniques has problems such as insufficient flexibility, poor thermal stability, severe neck-in and poor moldability. There are drawbacks such as occurrence on the film surface.

JP-A-53-88075 discloses EVOH.
And an ethylene polymer containing an epoxy group,
It is described that the adhesion to various substrates, especially metals, is remarkably improved. However, when EVOH having a high ethylene content as shown in the examples is blended, the gas barrier property is completely insufficient. It is.

[0007]

SUMMARY OF THE INVENTION The present invention does not have the above-mentioned problems, that is, it has good transparency and gas barrier properties, resistance to drop impact, bending resistance, airbag prevention, suitability for skin packs, An object of the present invention is to provide a laminate having flexibility such as suitability for a shrink film and interlayer adhesion, and a direct blow container, a tube and a film comprising the laminate.

[0008]

Means for Solving the Problems The present inventors have proposed a saponified ethylene-vinyl acetate copolymer (A) 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 an epoxy equivalent of 700
Olefin polymer obtained by introducing an epoxy group to 10000 (B) 40 to 5 consisting wt% the resin composition layer is carbo
Through an adhesive resin layer composed of an acid-modified olefin polymer
The laminate formed by laminating with a resin layer has excellent transparency and gas barrier properties, is much more flexible than a laminate using EVOH alone, and has a drop impact resistance, airbag prevention, and skin. It has been found that it is extremely useful as a laminate having excellent suitability for pack and shrink film and good interlayer adhesion. Furthermore, the direct blow container made of the laminate was found to be particularly useful, and the present invention was completed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The EVOH used in the present invention is:
It is a resin having 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 mol% or more. 20 ethylene content
If the amount is less than mol%, gelling tends to occur during melt molding, so that not only a beautiful molded product such as a film cannot be obtained, but also the gas barrier property under high humidity deteriorates. On the other hand, if the ethylene content is higher than 60 mol%, the gas barrier property is undesirably deteriorated. If the degree of saponification is less than 95 mol%, as in the case where the ethylene content is less than 20 mol%, gelation tends to occur during melt molding, and stable operation cannot be performed for a long time.

The melt index of EVOH (value measured under the conditions of a temperature of 190 ° C. and a load of 2160 g: where the melting point is around 190 ° C. or exceeds 190 ° C. is measured at a plurality of temperatures above the melting point under a load of 2160 g). , A value obtained by plotting the reciprocal of the absolute temperature on the abscissa and the melt index on the ordinate in a semilogarithmic graph and extrapolating 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 is 5 mol%
It may be modified with the following range of comonomer,
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-vinylpyrrolidone, N-normal butoxymethyl acrylamide, vinyl triacrylate Examples thereof include methoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, N- (2-dimethylaminoethyl) methacrylamide or a quaternary product thereof, and N-vinylimidazole or a quaternary product thereof.

The olefin polymer having an epoxy group introduced therein used in the present invention means that an olefin monomer and an epoxy group-containing ethylenically unsaturated monomer are randomly copolymerized, or an epoxy group is added to the olefin polymer. Modified olefin polymers and the like obtained by subjecting a group-containing ethylenically unsaturated monomer to graft polymerization using 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 and glycidyl ether of hydroxyl methacrylate. The modification amount is 700 to 700 in epoxy equivalent.
It is 10,000, more preferably 1000-6000.
Here, the epoxy equivalent is represented by the number of grams of a resin containing 1 g equivalent of an epoxy group. When the epoxy equivalent is less than 700, the thickening is severe and gelation occurs, and disadvantages such as impairing the moldability occur. On the other hand, when the epoxy equivalent exceeds 10,000,
Because of poor compatibility with EVOH, transparency of the composition,
Unsatisfactory mechanical properties.

Examples of the olefin monomer include ethylene, propylene, butylene and the like. Specific examples of the olefin polymer include polyethylene (low density, medium density, high density) and ethylene-propylene copolymer. And ethylene-α-olefin copolymers such as ethylene-butylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, butyl rubber, and the like. Particularly preferred is low-density polyethylene. , An ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer, and an ethylene-acrylate copolymer. The olefin-based polymer may be copolymerized with another unsaturated monomer in a small amount as long as the object of the present invention is not impaired. In addition, the MI of the olefin polymer having an epoxy group introduced in the present invention is not particularly limited, but is preferably 0.1 to 50 g / 10 minutes, and more preferably 0.5 to 15 g / 10 minutes.

The resin composition of the present invention is a mixture of EVOH (A) and an olefin polymer (B) into which an epoxy group has been introduced, and the compounding ratio is A / B = 60 to 95 /
40 to 5 (weight ratio), more preferably A / B = 70
90/30 to 10 (weight ratio). When the blending amount of the olefin polymer having an epoxy group introduced is less than 5% by weight based on the composition, drop impact resistance and bending resistance are poor. On the other hand, if it exceeds 40% by weight, not only the transparency is poor but also the gas barrier properties are poor.

As a method for mixing EVOH and an olefin polymer having an epoxy group introduced therein, there are methods using a Banbury mixer, a single-screw or twin-screw extruder, a Brabender plast mill, or the like. The molding may be performed while being supplied to the machine and kneading with the molding machine.
When kneading them, a plasticizer, a lubricant, an antioxidant, a colorant, various resins and the like may be added as long as the effects of the present invention are not impaired.

The laminate of the present invention comprises at least one resin composition layer as described above, wherein the resin composition layer is a carboxylic acid-modified oleate.
With a resin layer via an adhesive resin layer composed of a fin-based polymer
It is a laminated body that is laminated. At this time, the resin composition of the present invention can be used in any of the intermediate layer, the outermost layer, and the innermost layer, but is interposed between the resin composition layer and the resin layer.
It is important that the adhesive resin layer to be formed is a layer composed of a carboxylic acid-modified olefin polymer. Adhesion of such layer
By using a resin layer , it is possible to obtain a laminated body having excellent drop impact resistance, airbag prevention and interlayer adhesion, as is clear from the examples described later.

The carboxylic acid-modified olefin polymer is
Refers to an olefin polymer having a carboxyl group in the molecule, an unsaturated carboxylic acid or its anhydride is an olefin polymer, for example, low-density polyethylene, linear low-density polyethylene, polypropylene, polyolefin such as polybutylene, Copolymers of olefins with unsaturated monomers copolymerizable therewith (such as vinyl esters and unsaturated carboxylic esters), such as ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer.
And a modified olefin-based polymer obtained by chemically bonding (for example, by an addition reaction or a graft reaction).

Specifically, maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer, etc. are selected. One or two
Mixtures of more than one species are mentioned as suitable. Also, these carboxylic acid-modified olefin polymers include EVO
H, for example, the resin composition of the present invention can be mixed within a range that does not impair the effects of the present invention.

In the laminate of the present invention, the resin composition layer is
Adhesive resin layer composed of rubonic acid-modified olefin polymer
Are laminated with a resin layer via a resin layer. here,
The resin to be laminated with the resin composition layer is not particularly limited, and generally a resin having good transparency is preferable, but low-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, polybutene Such as polyolefins, ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, ionomers, copolymers based on olefins such as carboxylic acid-modified polyethylene, polystyrene, polyamide, polyethylene terephthalate, polycarbonate, poly Examples thereof include vinyl chloride and the like, and mixtures thereof. Of these, particularly preferably used are low-density polyethylene, linear low-density polyethylene, polypropylene, and ethylene-
It is a propylene copolymer or an ethylene-vinyl acetate copolymer alone or a mixture thereof.

The laminate of the present invention can be formed into a film, a sheet, a tube, a bottle, etc., and the thickness constitution of each layer is not particularly limited. It is preferably used in a thickness of 300 μ or less, more preferably 200 μ or less.

The method for laminating the resin composition of the present invention is not particularly limited, and examples thereof include a co-extrusion method, an extrusion lamination method, and a dry lamination method. It is preferable because the adhesiveness is good and the characteristics of the resin composition of the present invention can be exhibited.

The thus obtained laminate is suitable for a container having excellent drop impact resistance, particularly a direct blow container which is co-extruded and directly blow-molded. Moreover, since it is excellent in flexibility, it is also suitable for a tube excellent in airbag prevention. In addition, it can also be used as a bag-in-box excellent in bending resistance, a film excellent in suitability for skin pack, a good suitability for shrink film, and the like.

[0024]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. “Parts” or “%” in the examples are on a weight basis unless otherwise specified.

Example 1 EVOH having an ethylene content of 44 mol%, a saponification degree of a vinyl acetate component of 99.1 mol%, and a MI of 5.5 g / 10 min
70 parts, an epoxy equivalent of 1050, and an MI of 4.3 g /
A 15 μm-thick intermediate layer composed of 30 parts of glycidyl methacrylate random copolymerized low-density polyethylene for 10 minutes, and 30 μm-thick 4-methyl-1 on both sides of the intermediate layer.
Pentane as a copolymer component, a surface layer composed of linear low-density polyethylene containing 3.2 mol% of the copolymer component and having an MI of 2.1 g / 10 min, and acetic acid having a thickness of 5 μm between each layer. Extrusion of three laminated films having a total thickness of 85 μm arranged via an adhesive resin layer composed 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. Using a three-layer, five-layer multilayer die head. As the resin composition used for the intermediate layer, pellets previously blended by an extruder were used.

The obtained laminated film is subjected to a gelbo flex test until the occurrence of pinholes in the laminated film is observed. It was measured under the condition of% RH. The sample of flex fatigue at each stage was a plane of 12 inches × 8 inches and measured at the center. The measuring method is as follows.

The flex resistance was evaluated by using a gelbo flex tester manufactured by Rigaku Kogyo Co., Ltd., forming a 12-inch × 8-inch film into a cylindrical shape having a diameter of 3.5 inches. At a distance of 7 inches, a grip distance of 1 inch at the maximum bending, a twist of 440 degrees at the first 3.5 inches of the stroke, and a reciprocating motion of a linear horizontal movement for the next 2.5 inches is repeated 40 times. The test was carried out at a rate of times / minute at 20 ° C. and 65% RH.

The measurement of the oxygen gas permeation amount (OTR) is determined by Mo
OX-TRAN 10 manufactured by dern Control
It measured using 20A and 65% RH conditions using -50A. The haze was measured using a Poick integrating sphere light transmittance meter of Nippon Seimitsu Optics Co., Ltd.

As a result of the evaluation, there was almost no change in the oxygen gas permeation amount in the bending fatigue test process until the pinhole was generated. The occurrence of pinholes was not observed until the flex fatigue test passed 7000 reciprocations. After the elapse of 7,100 reciprocations, it was recognized that one pinhole had already occurred when the inspection for pinholes was performed. . Also, no delamination between the layers was observed. The haze of the film was 5%, the transparency was good, and no streaks or satin were observed. The measurement results are shown in Table 1.

Comparative Example 1 In Example 1, the intermediate layer had an ethylene content of 44 mol%, a degree of saponification of a vinyl acetate component of 99.1 mol%, and a MI of MI.
Was used in the same manner as in Example 1 except that EVOH alone was used at 5.5 g / 10 minutes, and various evaluations were made. Table 1 shows the results. The film has poor flexibility and poor flex fatigue resistance.

Comparative Example 2 In Example 1, the intermediate layer had an ethylene content of 44 mol%, a degree of saponification of the vinyl acetate component of 99.1 mol%, and a MI of
Example 1 except for using an intermediate layer consisting of 70 parts of 5.5 g / 10 min EVOH and 30 parts of glycidyl methacrylate random copolymerized low density polyethylene having an epoxy equivalent of 600 and an MI of 4.3 g / 10 min. A laminated film was prepared in the same manner as described above, and various evaluations were made. Table 1 shows the results
Shown in The film has many gels and fish eyes, has insufficient flexibility, and has insufficient bending fatigue resistance.

Comparative Example 3 In Example 1, the intermediate layer had an ethylene content of 88 mol%, a degree of saponification of the vinyl acetate component of 98.0 mol%, and a MI of
Glycidyl methacrylate random copolymerized low-density polyethylene 30 having an EVOH of 70 parts and an epoxy equivalent of 1050, and an MI of 4.3 g / 10 minutes.
A laminated film was produced in the same manner as in Example 1 except that an intermediate layer consisting of a part was used, and various evaluations were made. Table 1 shows the results. Although the film has good flexibility and bending fatigue resistance, it has extremely poor gas barrier properties.

Comparative Example 4 In Example 1, the adhesive resin layer had a vinyl acetate content of 20.
A laminated film was prepared in the same manner as in Example 1 except that an ethylene-vinyl acetate copolymer which was not maleic anhydride-modified by weight% was used, and various evaluations were made. Table 1 shows the results
Shown in Although the film has good flexibility, 10
Delamination occurred in the bending tests, and the interlayer adhesion was poor.

[0034]

[Table 1]

Reference Example 1 EVOH having an ethylene content of 44 mol%, a saponification degree of a vinyl acetate component of 99.1 mol%, and a MI of 5.5 g / 10 min.
70 parts, an epoxy equivalent of 2900, and an MI of 4.1 g /
An intermediate layer composed of 30 parts of glycidyl methacrylate random copolymer modified low-density polyethylene for 10 minutes and having an average thickness of 50 μm, 70 parts of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5% by weight on both sides of the intermediate layer, and maleic anhydride An average thickness of all layers consisting of 30 parts of a maleic anhydride-modified ethylene-vinyl acetate copolymer having an acid content of 0.5% by weight is 300 μm each.
Was obtained by coextrusion and direct blow molding using two extruders and a multilayer die head for two and three layers. Here, as the resin composition used for the intermediate layer, pellets previously blended by an extruder were used. This container is filled with 10 L of water,
Although it was dropped three times from a height of m, it did not break and showed good impact resistance.

Comparative Example 5 In Example 2, the ethylene content was 44 mol%, the degree of saponification of the vinyl acetate component was 99.1 mol%, and the MI was 5.5 g.
Except that the EVOH alone was used as the resin for the intermediate layer,
A multilayer direct blow container was molded in the same manner as in Example 2, and a similar drop test was performed. This container was destroyed by the first drop and had poor impact resistance.

Comparative Example 6 In Example 2, 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.
70 parts of EVOH / 10 minutes and epoxy equivalent of 18000
A multi-layer direct blow container was molded in the same manner as in Example 2, except that a resin composition comprising 30 parts of glycidyl methacrylate copolymer modified low-density polyethylene having an MI of 3.5 g / 10 min was used as the resin for the intermediate layer. Then, a similar drop test was performed. This container was also broken by the first drop, and had poor impact resistance.

Comparative Example 7 A multilayer direct blow container was formed in the same manner as in Example 2 except that the ethylene-vinyl acetate copolymer having a vinyl acetate content of 5% by weight was used alone on both sides of the intermediate layer. Then, a similar drop test was performed. This container was delaminated by the first drop, and had poor impact resistance.

Example 2 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, epoxy equivalent of 2900, MI of 4.1 / 1
An intermediate layer having an average thickness of 20 μm and 30 parts of glycidyl methacrylate random copolymer modified low-density polyethylene of 0 minute, 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
.mu. surface layer and a 15 .mu.m thick adhesive resin layer comprising a maleic anhydride-modified ethylene-vinyl acetate copolymer having a thickness of 15 .mu.m and containing 20% by weight of vinyl acetate and 0.5% by weight of maleic anhydride. Was obtained by co-extrusion and direct blow molding using three extruders, three kinds of five-layer multilayer die heads. Here, as the resin composition used for the intermediate layer, pellets previously blended by an extruder were used.

The center of the body of the obtained tube is 15 mm in width.
And cut it with a loop stay
The resilience upon compression was 700 mg. here,
Loop stiffness is measured by using a loop stiffness tester manufactured by Toyo Seiki Co., Ltd. to convert a 15 mm wide film to a 60 m long.
The repulsive force was measured under the conditions of 20 ° C. and 65% RH when bent into a loop shape of m and compressed until the loop diameter became 20 mm. Loop stiffness is important as a measure of airbag prevention, and it is considered that a composition having low loop stiffness has good airbag prevention.

Comparative Example 8 In Example 3, the intermediate layer had an ethylene content of 44 mol%, a degree of saponification of the vinyl acetate component of 99.1 mol%, and a MI of
In addition to using EVOH alone at 5.5 g / 10 minutes, a multilayer tube was formed in the same manner as in Example 3 and a loop stiffness test was performed.
Met.

Comparative Example 9 In Example 3, the adhesive resin layer had a vinyl acetate content of 20.
A multilayer tube was molded and subjected to a loop stiffness test in the same manner as in Example 3 except that an ethylene-vinyl acetate copolymer which was not maleic anhydride-modified by weight% was used. there were. But,
The multilayer tube delaminated during the test.

[0043]

The laminate of the present invention has excellent transparency and gas barrier properties, is much more flexible than a laminate using EVOH alone, has resistance to drop impact, airbag prevention and skin. It is extremely useful as a laminate excellent in pack suitability and shrink film suitability. A direct blow container using this laminate is excellent in drop impact resistance, airbag prevention, and interlayer adhesion.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // (C08L 29/04 23:26)

Claims (4)

(57) [Claims] 1. A saponified ethylene-vinyl acetate copolymer (A) having an ethylene content of 20 to 60 mol% and a degree of saponification of a vinyl acetate component of 95 mol% or more and an epoxy equivalent of 700 to 95% by weight. The resin composition layer composed of 40 to 5% by weight of an olefin polymer (B) having 10,000 epoxy groups introduced therein is a carboxylic acid-modified olefin polymer.
A laminated body laminated with a resin layer via an adhesive resin layer made of the same. 2. A direct blow container comprising the laminate according to claim 1. 3. A tube comprising the laminate according to claim 1. 4. A film comprising the laminate according to claim 1.