JP2983068B2 - Laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate, and more particularly, to a polyolefin resin layer / ethylene-vinyl acetate copolymer via an adhesive layer with an ethylene-vinyl acetate copolymer saponified layer as an intermediate layer. It is an object of the present invention to provide a laminate having excellent barrier properties even in a high-temperature and high-humidity state, in which a layer of a mixed composition of an oxide / ethylene copolymer and an innermost and outermost layer are composed of a polyolefin-based resin layer.

[0002]

2. Description of the Related Art Saponified ethylene-vinyl acetate copolymer is a thermoplastic resin which is mechanically good and has excellent gas barrier properties, fragrance retention properties, oil resistance and the like. However, since it is hydrophilic, it has the disadvantage that the above properties are lost when exposed to a high humidity atmosphere or when it comes into contact with a polar solvent such as water or alcohol. Therefore, a laminate comprising at least three layers of a saponified ethylene-vinyl acetate copolymer and a hydrophobic polyolefin, particularly a saponified ethylene-vinyl acetate copolymer as an intermediate layer, and an innermost and an outermost layer thereof via an adhesive layer A laminate consisting of three layers and five layers, each of which is protected by a polyolefin, is frequently used in the current market.

However, in recent years, sterilization, sterilization, and the like have become necessary in the fields of foods, pharmaceuticals, and the like, and materials having excellent gas barrier properties in a high-temperature and high-humidity state such as retort treatment have been demanded. The loss of the water vapor barrier effect of the polyolefin layer at the time has led to a decrease in the barrier properties of the saponified ethylene-vinyl acetate copolymer under humid conditions, and has a drawback that it does not play a role as a barrier material.

[0004]

Thus, the saponified ethylene-vinyl acetate copolymer of the prior art is used as the intermediate layer,
The laminate in which the innermost and outermost layers are made of polyolefin via the adhesive layer has a problem that the gas barrier property is significantly deteriorated under high temperature and high humidity conditions such as retort treatment. From the above, the present invention does not have these drawbacks (problems), that is, takes advantage of the gas-barrier properties and fragrance retention properties of the saponified ethylene-vinyl acetate copolymer, and can be used under high temperature and high humidity conditions such as retort treatment. To obtain a laminate in which the gas barrier properties do not significantly deteriorate.

[0005]

According to the present invention, these objects are attained in that the ethylene copolymerization ratio is 10 to 65 mol% and the ethylene-vinyl acetate copolymer is at least 90%.
The saponified ethylene-vinyl acetate copolymer layer obtained by the above saponification is used as an intermediate layer, and (a) copolymerization of (b) ethylene with respect to 100 parts by weight of the polyolefin resin is performed via an adhesive layer. The ratio is 10 to 65 mol%
And an ethylene-vinyl acetate copolymer of at least 9
10 to 90 parts by weight of a saponified ethylene-vinyl acetate copolymer obtained by saponifying 0% or more (c) an ethylene copolymer of ethylene and an ethylenically unsaturated monomer containing an epoxy group, or a vinyl copolymer thereof; A solution in which the layer of the mixed composition and the innermost and outermost layers comprise a polyolefin-based resin layer in which a copolymer with an ester and / or an unsaturated carboxylic acid is mixed in an amount of 5 to 90 parts by weight. it can.

Hereinafter, the present invention will be described specifically. A. Polyolefin resinA typical example of the polyolefin resin used for the polyolefin resin layer and the mixture layer used for producing the polyolefin resin layer of the present invention is polypropylene, and other examples include a random mixture of propylene and ethylene. Or a block copolymer, a random or block copolymer of propylene and / or ethylene and at most 12 other α-olefins (copolymerization ratio with α-olefin is at most 20% by weight), Examples thereof include a homopolymer of ethylene, a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, and a homopolymer of an α-olefin having 4 to 6 carbon atoms.

Further, the present invention also includes a modified polyolefin obtained by graft-polymerizing a compound having at least one double bond (eg, an unsaturated carboxylic acid or a vinylsilane compound) to these polyolefin resins. . These polyolefin resins and modified polyolefins may be used alone or in combination of two or more. In addition, among these polyolefin resins and modified polyolefins,
Two or more kinds may be used as a resin blend at an arbitrary ratio.

Further, an inorganic filler may be further added to these polyolefin resins, and the inorganic filler is generally widely used in the fields of synthetic resins and rubbers. As these inorganic fillers, those which do not react with oxygen and water and which do not decompose during kneading and molding are preferably used.

As the inorganic filler, aluminum,
Metal oxides such as copper, iron, lead, nickel, magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony, and titanium, hydrates (hydroxides), sulfates, carbonates, and silicic acids Compounds such as salts,
These double salts and their mixtures are roughly classified.

Representative examples of the inorganic filler include the above-mentioned aluminum oxide (alumina), its hydrate, calcium hydroxide, magnesium oxide (magnesia), magnesium hydroxide, zinc oxide (zinc white), lead tin and Lead oxide such as lead white, magnesium carbonate, calcium carbonate, basic magnesium carbonate, white carbon, asbestos, mica, talc, glass fiber, glass powder, glass beads, clay, diatomaceous earth, silica, wollastonite, oxidation Examples include iron, antimony oxide, titanium oxide (titania), lithobon, pumice powder, aluminum sulfate (eg, gypsum), zirconium silicate, zirconium oxide, barium carbonate, dolomite, molybdenum disulfide, and iron sand.

Among these inorganic fillers, the powdery ones having a diameter of 20 μm or less (preferably 10 μm or less) are preferable. In the case of a fibrous material, the diameter is 1 to 500.
μm (preferably 1 to 300 μm) and a length of 0.1
の も の 6 mm (preferably 0.1-5 mm) is desirable. Further, the plate-like one has a diameter of 30 μm or less (preferably
μm or less) is preferred. Among these inorganic fillers, those in the form of a plate (flake) and those in the form of powder are particularly preferred.

The melt index of the polyolefin resin (measured under the conditions of 14 according to JIS K7210, hereinafter referred to as "MI (1)") is usually 0.005 to 100 g.
/ 10 min, preferably from 0.01 to 80 g / 10 min, and particularly preferably from 0.02 to 50 g / 10 min. If a polyolefin resin having an MI (1) of less than 0.005 g / 10 minutes is used, extrusion molding cannot be performed due to poor fluidity, and a sheet layer cannot be formed. On the other hand, 100
If you use a polyolefin resin exceeding g / 10 minutes,
When manufacturing these co-extruded sheets, it is not possible to obtain a good product having a large drawdown.

When the inorganic filler is blended, the blending ratio of the inorganic filler in the total amount of the polyolefin resin and the inorganic filler is generally at most 80% by weight, and 70% by weight or less. Preferably, it is particularly preferably at most 60% by weight. If the blending ratio of the inorganic filler in the total amount exceeds 80% by weight, it is difficult to form a sheet by extrusion and a good sheet cannot be obtained.

B. Saponified ethylene-vinyl acetate copolymer In the present invention, the saponified ethylene-vinyl acetate copolymer used in the saponified ethylene-vinyl acetate copolymer layer and the ethylene-vinyl acetate copolymer used in the mixed composition layer The saponified polymer contains at least 9 ethylene-vinyl acetate copolymers having an ethylene content of 10 to 65 mol%.
It is saponified at 0 mol% or more.

Further, those having a molecular weight which can be formed into a film or a sheet are desirable, and a melt index [JIS K7
According to 210, temperature is 210 ℃ and load is 2.16kg
And hereinafter referred to as "MI (2)"].
g / 10 min, preferably 0.1-20 g / 10 min. When a saponified ethylene-vinyl acetate copolymer having an MI (2) of less than 0.1 g / 10 minutes is used to produce a laminate,
Since the fluidity of the resin is low, the resin does not flow and a good laminate cannot be obtained. On the other hand, when a saponified ethylene-vinyl acetate copolymer exceeding 20 g / 10 minutes is used, when a laminate is produced, the fluidity of the resin is too high to obtain a good laminate.

C. Ethylene copolymer In the present invention, the melt index of the ethylene copolymer used in the mixed composition layer (measured under the condition 4 according to JIS K7210, hereinafter referred to as “MI (3)”) is usually 1.0.
To 1,000 g / 10 min, preferably 1.0 to 800 g / 10 min, and particularly preferably 2.0 to 700 g / 10 min. When an ethylene copolymer having an MI (3) of less than 1.0 g / 10 minutes is used, the compatibility in the mixed composition layer is poor, so that only those having significantly reduced impact resistance can be obtained, and the polyolefin-based copolymer can be obtained. Adhesion with the resin layer is poor, and a practically usable laminate cannot be obtained. MI (3) is 1,000g / 10
If an ethylene copolymer exceeding the amount is used, the compatibility in the mixed composition layer similarly deteriorates, so that the impact resistance decreases,
Poor adhesion with the polyolefin-based resin layer occurs, and a laminated body that can withstand practical use cannot be obtained.

Further, the ethylene copolymer used in the mixed composition layer in the present invention may be an ethylene copolymer composed of ethylene and a comonomer (1) whose representative examples are described later. ) And a comonomer (2) whose representative examples are described below. Comonomer (1) is an ethylenically unsaturated monomer containing an epoxy group.

Representative examples of the comonomer (1) include those represented by the following formulas (formulas (I) and (II)).

Embedded image

Embedded image (In these formulas, R ₁ , R ₂ , R ₃ and R ₄ may be the same or different and are a hydrogen atom or a methyl group, and R ₅ is a linear or branched alkylene group having 1 to 12 carbon atoms. Typical examples of the epoxy compounds represented by the formulas (I) and (II) include glycidyl methacrylate, glycidyl acrylate, α-methyl glycidyl acrylate, α-methyl glycidyl methacrylate, vinyl glycidyl ether, and allyl. Glycidyl ether and methacryl glycidyl ether;

Furthermore, the comonomer (2) is selected from vinyl esters and unsaturated carboxylic esters. Among the comonomers (2), the vinyl ester generally has 4 to 25 carbon atoms, preferably 4 to 20 carbon atoms, and more preferably 4 to 16 carbon atoms. Representative examples of suitable vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, and the like.

The unsaturated carboxylic acid ester usually has 4 to 40 carbon atoms, preferably 4 to 30 carbon atoms, and particularly preferably 4 to 20 carbon atoms. Representative examples of suitable unsaturated carboxylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate and the like.
In addition, alkoxyalkyl (meth) acrylate as an unsaturated carboxylic acid ester is also exemplified as a comonomer. The alkoxyalkyl (meth) acrylate preferably has an alkyl group having 1 to 8 (preferably 1 to 4) carbon atoms. It is desirable that the alkoxy group has 1 to 8 (preferably 1 to 4) carbon atoms. Representative examples of suitable alkoxyalkyl (meth) acrylates include methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, and butoxyethyl (meth) acrylate.

D. Mixing ratio of mixed composition and its production Mixing ratio of each resin used in the mixed composition layer of the present invention,
The saponified ethylene-vinyl acetate copolymer is 10 to 90 parts by weight and the ethylene copolymer is 5 to 90 parts by weight with respect to 100 parts by weight of the polyolefin resin, and the proportion of the polyolefin resin in the mixture composition is It is 20 to 80 parts by weight, preferably 30 to 70% by weight.

If the proportion of the polyolefin resin in the mixed composition is less than 10% by weight, the adhesion to the innermost and outermost polyolefin layers is weak and a laminate which can withstand practical use cannot be obtained. Only those having significantly deteriorated gas barrier properties under high temperature and high humidity conditions such as treatment can be obtained.

The ratio of the saponified ethylene-vinyl acetate copolymer in the mixture is as follows:
The amount is 10 to 90 parts by weight, preferably 15 to 80 parts by weight based on 00 parts by weight. If the amount is less than 10 parts by weight, only a gas barrier property remarkably deteriorated under high-temperature and high-humidity conditions such as a retort treatment can be obtained. I can't get my body.

The proportion of the ethylene copolymer resin in the mixed composition is from 5 to 90 parts by weight, preferably from 10 to 80 parts by weight, based on 100 parts by weight of the polyolefin resin. If the proportion of the ethylene-based copolymer resin is less than 5 parts by weight, the dispersion of the saponified ethylene-vinyl acetate copolymer in the mixed composition is poor, so that the impact resistance is remarkably low or under high temperature and high humidity conditions. The effect of preventing deterioration of gas barrier properties is not exhibited.

On the other hand, if it exceeds 90 parts by weight, only those having significantly deteriorated gas barrier properties under low temperature and high humidity conditions such as retort treatment, low impact resistance, or poor adhesion to the polyolefin layer can be obtained. A laminated body that can withstand practical use cannot be obtained due to any of the problems.

The production of the mixed composition of the present invention may be carried out by mixing the resins constituting the mixed composition with a mixing mixer such as a tumbler, a Henschel mixer or a super mixer.
It is also obtained by mixing with a mixing mixer of the raw material supply system before the extruder, and further kneading each resin constituting the mixed composition is generally used in the synthetic resin field such as a screw type extruder, a Banbury mixer, a kneader and the like. It can also be produced by melt mixing using a machine.

E. Production of laminate The laminate of the present invention comprises a saponified ethylene-vinyl acetate copolymer layer as an intermediate layer, and the above-described mixed composition layer and the innermost and outermost layers each comprising a polyolefin resin layer via an adhesive layer. It is a laminate. A laminate of these layers can be obtained by a generally known coextrusion method, for example, a film, a sheet by coextrusion T-die molding, a film, a sheet by cocircular die molding, a container, a bottle, a co-injection by coextrusion hollow molding. Various types of containers such as various containers can be obtained by molding.

The extrusion temperature of the coextrusion molding for obtaining the laminate of the present invention is generally from 100 to 350 ° C., and from 150 to 3 ° C.
30 ° C is suitable, and particularly preferably 180 to 300 ° C.

The thickness of each layer of the laminate of the present invention is 2 to 500 μm, preferably 5 to 300 μm, for the saponified ethylene-vinyl acetate copolymer layer as the intermediate layer. If the thickness of the saponified ethylene-vinyl acetate copolymer layer constituting the intermediate layer is less than 2 μm, the gas barrier effect is poor.
If it exceeds μ, it is effective, but the cost increases and the product becomes impractical.

The thickness of the mixed composition layer is 10 to 300 on one side.
0 μ, preferably 15 to 2000 μ. When the thickness of the mixed composition layer is less than 10 μm, the effect of preventing the gas barrier property from deteriorating under high temperature and high humidity conditions is not exhibited.
If it exceeds μ, it will be difficult to mold and produce a product with poor practicality.

Further, the polyolefin resin layer constituting the innermost and outermost layers has a thickness of 10 to 3000 μm on one side, preferably 15 to 3000 μm.
２０００2000 μm. When one surface of the polyolefin layer as the innermost and outermost layers is less than 10 μm, there is no effect of preventing the gas barrier property from deteriorating under high-temperature and high-humidity conditions.

In the present invention, the adhesive between the saponified ethylene-vinyl acetate copolymer and the mixture layer is a maleic adhesive which is a known adhesive between the saponified ethylene-vinyl acetate copolymer and a polyolefin resin. A resin made of an acid-modified polyolefin or the like may be used as the adhesive layer resin.

[0033]

The present invention will be described in more detail with reference to the following examples. The oxygen permeability of each sample in Examples and Comparative Examples was measured using an oxygen permeation measuring apparatus “Modern Control (USA) Model OX-RTAN10 / 50” at a measurement temperature of 23 ° C. and a relative humidity of 60%. . Also,
For the adhesive strength, a sample of 15 mm width was sampled from the obtained laminated sheet, and this material was collected at a take-off speed of 100 mm / min.
A peel test was performed in the direction of 80 degrees to determine the adhesive strength. Further, the impact resistance strength of the sheet is determined by cutting a 150 mm wide × 150 mm wide sheet from the manufactured laminated sheet to prepare a measurement sample, and performing a falling weight impact test at 23 ° C. in accordance with ASTM D 1709. The sexual strength was determined. The types and physical properties of the polyolefin resin, the saponified ethylene-vinyl acetate copolymer, and the ethylene copolymer used in Examples and Comparative Examples are shown below.

[(A) Polyolefin-based resin] As a polyolefin-based resin, an ethylene-propylene block copolymer having MI (1) of 0.6 g / 10 minutes and a copolymerization ratio of ethylene of 18% by weight [hereinafter referred to as ""PP(A)"], a propylene homopolymer having an MI (1) of 2.0 g / 10 min [hereinafter referred to as "PP (B)"], and a MI (3) of 0.2 g / 10 min. An ethylene homopolymer having a density of 0.955 g / cm ³ (hereinafter referred to as “PE (1)”),
A mixture containing 85% by weight of PP (A) and 15% by weight of PE (1) [hereinafter referred to as "PP (c)"] was used.

[(B) Saponified ethylene-vinyl acetate copolymer] As a saponified ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate copolymer having a copolymerization ratio of ethylene of 25 mol% is saponified. [Saponification degree: 99%, MI (2) 5.0 g /
10 minutes, hereinafter referred to as "EVOH (1)"]. Further, as a saponified ethylene-vinyl acetate copolymer, a saponified product obtained by saponifying an ethylene-vinyl acetate copolymer having a copolymerization ratio of ethylene of 38 mol% [a saponification degree of 99%, MI (2) 3.0 g / 10 min, hereinafter referred to as “EVOH
(2) ").

[(C) Ethylene-based copolymer] As an ethylene-based copolymer, an ethylene-vinyl acetate-glycidyl methacrylate copolymer having MI (3) of 50 g / 10 minutes [[copolymerization ratio of vinyl acetate] 6.0% by weight and a copolymerization ratio of glycidyl methacrylate of 12.5% by weight] are hereinafter referred to as "EAG (1)".] Ethylene-vinyl acetate-glycidyl methacrylate having MI (3) of 3.0 g / 10 min. The acrylate copolymer [the copolymerization ratio of vinyl acetate 5.0% by weight and the copolymerization ratio of glycidyl methacrylate 11.5% by weight] is hereinafter referred to as "EAG (2)". MI (3) 7.0 g
/ 10 min. Ethylene-vinyl acetate-glycidyl methacrylate copolymer [[vinyl acetate copolymerization ratio 3.0
8. wt%, copolymerization ratio of glycidyl methacrylate
[EAG (3)] was used.

[(D) Adhesive] The adhesive between the saponified ethylene-vinyl acetate copolymer and the mixture layer is a modified polyolefin resin ER321P manufactured by Showa Denko K.K. ER321P], and a modified polyolefin resin ER403 (hereinafter referred to as "ER403") manufactured by Showa Denko KK when the innermost and outermost layers were made of polyethylene resin.

Examples 1 to 5 and Comparative Examples 1 to 4 An extruder having an L / D = 24 and a diameter of 65 mmφ was prepared by mixing the mixed compositions constituting the mixed composition layer at the mixing ratio of each resin shown in Table 1. The mixture was kneaded and mixed at an extrusion temperature of 220 ° C. to prepare pellets for a mixed composition layer.

Next, the obtained pellets for the mixed composition layer,
And a polyolefin resin, an adhesive resin, and a saponified ethylene-vinyl acetate copolymer resin of four types and seven layers (manufactured by Toshiba Machine Co., Ltd., two feed block 65 mmφ extruders, 40 mmφ extruders) 2) using a polyolefin-based resin layer / mixed composition layer / adhesive layer / ethylene-vinyl acetate copolymer saponified layer / adhesive layer / mixed composition layer / polyolefin-based resin layer A laminated sheet having a target structure having a saponified vinyl copolymer layer as a central layer was produced.

In the production of the laminated sheet, the polyolefin resin layer was extruded at an extrusion temperature of 23 mm using a 65 mm diameter extruder.
At 0 ° C., the mixed composition layer uses a 40 mm diameter extruder, the extrusion temperature is 230 ° C., the adhesive layer uses a 40 mm diameter extruder, the extrusion temperature is 220 ° C., and the ethylene-vinyl acetate copolymer saponified layer is Extrusion temperature 2 using a 40 mm diameter extruder
At 00 ° C., a laminated sheet was manufactured with the configuration of each layer shown in Table 2. Table 2 shows the results of measuring the adhesive strength and the impact resistance of each of the thus obtained laminated sheets.

Further, a container having a diameter of 81.2 mm, a depth of 40 mm and a capacity of 160 cc was manufactured from each of the laminated sheets by using a vacuum forming machine (model FLX02, manufactured by Asano Research Laboratory Co., Ltd.). Then, each of the obtained containers is filled with water so that 5% of the total content becomes a space portion, and a propylene-based polymer having a thickness of 60 μm on both sides is interposed between aluminum foils having a thickness of 20 μm. The manufactured lid is heated at a temperature of 200 ° C. and a pressure of 2.5
Ring sealing was performed for 3 seconds under the condition of kg / cm ² to prepare a container filled with water. This container was placed in a retort pot (Daiwa Seikan, pneumatic type, retort treatment device) and retorted at 120 ° C. for 20 minutes. Table 2 shows the results of measuring the oxygen permeability of the retorted container and the unretorted container with an oxygen permeation measuring device.

In Comparative Examples, pellets of the mixed compositions 6 to 9 shown in Table 1 having a resin composition outside the scope of the present invention were prepared.
A laminated sheet having the configuration shown in Table 2 was manufactured. Then, the adhesive strength and the impact resistance strength of the obtained laminated sheet were measured, and the results are shown in Table 2. Further, a container was prepared from the obtained laminated sheet by vacuum forming in the same manner as in Example 1, and the oxygen permeability of the container subjected to the retort treatment and the container not subjected to the retort treatment were measured. The obtained results are shown in Table 2.

The results obtained as described above are shown in Table 2 as Examples and Comparative Examples. The laminated sheet of the present invention has high adhesive strength, excellent impact resistance, and before and after retort treatment. It is clear that the barrier properties have hardly changed.

Table 1 Mixing ratio of each resin in the mixed composition layer

[0045]

[Table 2]

[0046]

The laminate of the present invention can be formed by coextrusion T-die molding, coextrusion circular die molding, coextrusion hollow molding, coextrusion injection molding, etc., into films, sheets, pipes, and various containers such as balls and trays. It is molded into containers shaped like bottles, bottles, and tanks, and is used in a wide range of fields, such as general food packaging, chemicals, pharmaceuticals, and general industrial applications. Excellent effect in the field of use.

Claims (1)

(57) [Claims] An ethylene-vinyl acetate copolymer saponified layer obtained by saponifying at least 90% or more of an ethylene-vinyl acetate copolymer having an ethylene copolymerization ratio of 10 to 65 mol%. And (b) a copolymerization ratio of (b) ethylene to 10 to 65 parts by weight with respect to 100 parts by weight of the polyolefin-based resin.
Mol%, wherein the saponified ethylene-vinyl acetate copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer by at least 90% or more. Wherein the layer and the innermost and outermost layers of the mixed composition are a mixture of an ethylene copolymer with an unsaturated unsaturated monomer or a copolymer thereof with a vinyl ester and / or an unsaturated carboxylic acid in an amount of 5 to 90 parts by weight. A laminate comprising a base resin layer.