JPH07108655A - Laminate having gas barrier properties - Google Patents

Abstract

PURPOSE:To obtain a laminate having an adhesive layer imparting strong adhesive force generating no delamination by forming a barrier layer from an ethylene/vinyl alcohol copolymer and forming the adhesive layer from an adhesive compsn. prepared by compounding a tackifier with a specific saponified ethylene/vinyl acetate copolymer. CONSTITUTION:A laminate has at least one combination of barrier layer/ adhesive layer/thermoplastic resin layer in its laminated structure and also contains a laminated structure having a combination of various thermoplastic resin layers other than the aforementioned combination. The barrier layer is composed of an ethylene/vinyl alcohol copolymer and the adhesive layer is composed of an adhesive compsn. wherein 30-90 pts.wt. of an ethylene/vinyl acetate copolymer with vinyl acetate content of 8-42wt.% and a melt flow rate of 0.1-70g/10min, 5-40 pts.wt. of a saponified ethylene/vinyl acetate copolymer with vinyl acetate content of 10-70wt.% and a saponification value of 5-100% and 5-30pts.wt. of a tackifier are compounded so that the total amt. becomes 100 pts.wt.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a gas barrier laminate which does not cause delamination during processing or during use, particularly when processed into a container and sealed with a lid material, the sealed lid material is used. The present invention relates to a gas barrier layered product in which the barrier layer does not peel off when removed.

[0002]

2. Description of the Related Art A food container made of a thermoplastic resin is usually laminated with a gas barrier layer in order to block oxygen and prevent the contents from being altered. Generally, an ethylene-vinyl alcohol copolymer layer is used as the gas barrier layer, which is laminated on the thermoplastic resin layer via an ethylene-vinyl acetate copolymer-based adhesive layer. Copolymer adhesives have a low adhesive strength to ethylene-vinyl alcohol copolymer, so they often peel off when subjected to a small impact or friction during transportation or use, and in containers with sealed lids. However, there is a drawback that the surface layer of the container is peeled off from the adhesive layer portion when the lid material is removed.

Recently, an adhesive having improved adhesion between polyolefin and ethylene-vinyl alcohol copolymer has been developed. However, this adhesive has insufficient adhesion to polystyrene, polycarbonate, polyamide and polyethylene terephthalate, In order to obtain a laminate containing these thermoplastic resin layers, other adhesives having a large adhesive force to these thermoplastic resins must be used in combination, the ethylene-vinyl alcohol copolymer layer and polyethylene, polystyrene, To date no adhesives have been known which can be used alone in a laminate comprising a layer of polycarbonate, polyamide or polyethylene terephthalate.

[0004]

DISCLOSURE OF THE INVENTION The present invention is directed to a laminate obtained by laminating an ethylene-vinyl alcohol copolymer as a barrier layer on a thermoplastic resin substrate layer, and removing a lid material which is being transported, used or sealed. At that time, it was made for the purpose of obtaining a product having an adhesive layer which gives a strong adhesive force without causing delamination.

[0005]

The present inventors have been keen to develop an adhesive layer suitable for being interposed between an ethylene-vinyl alcohol copolymer layer and another thermoplastic resin layer. As a result of repeated research, it is possible to significantly increase the adhesive strength by adding a specific amount of a tackifier to an ethylene-vinyl acetate copolymer-based resin composition having a specific composition. However, the inventors have found that they also have a strong adhesive force to polystyrene, polycarbonate, polyamide, and polyethylene terephthalate, and have completed the present invention based on this finding.

That is, according to the present invention, in a laminate comprising a structure in which the barrier layer is laminated with another thermoplastic resin layer via an adhesive layer, (A) the barrier layer is composed of an ethylene-vinyl alcohol copolymer, B) The adhesive layer has a vinyl acetate content of 8 to 42% by weight and a melt flow rate of 0.1 to 70.
g / 10 min ethylene-vinyl acetate copolymer 30-90
1 part by weight, 5 to 40 parts by weight of vinyl acetate content, 10 to 70% by weight of vinyl acetate, 5 to 40% by weight of saponified ethylene-vinyl acetate copolymer and 5 to 30 parts by weight of tackifier.
The present invention provides a gas barrier laminate, which comprises an adhesive composition formulated to be 100 parts by weight.

In the laminate of the present invention, as the base material layer,
Polyolefin, polystyrene such as polyethylene, polypropylene, ethylene-propylene copolymer, copolymer of ethylene and α-olefin having 4 or more carbon atoms, polystyrene,
Polycarbonate, polyamide, polyethylene terephthalate and the like are preferable, but other thermoplastic resins such as polyvinyl chloride, polyvinylidene chloride, acrylic resin, polyacetal, and fluororesin can be used if desired.

[0008] Among them, the use of polystyrene gives thermoformability and rigidity, the use of polyolefin gives moisture resistance, and the use of polyamide, polycarbonate, polyethylene terephthalate gives a laminate excellent in chemical resistance and abrasion resistance. Obtainable.

Next, in the present invention, an ethylene-vinyl alcohol copolymer is used as the barrier layer, which has an ethylene content of 25 to 50 mol%, a melt flow rate (JIS K7210, 190 ° C., a load of 2160 g). ) Is preferably 0.5 to 25 g / 10 minutes. If the ethylene content is less than 25%, the molding temperature range will be narrow, and melt molding will be difficult and the stretchability will be poor. 50%
If it is larger than the above range, the gas barrier property is deteriorated, which is not preferable. The melt flow rate is 0.5 to 25 g /
If it is outside the range of 10 minutes, poor flowability may occur, or the moldability may be poor, so that lamination by coextrusion with another thermoplastic resin becomes difficult.

In the present invention, as the adhesive layer, (a)
It has a vinyl acetate content (JIS K6730) of 8 to 42% by weight, preferably 10 to 20% by weight, and a melt flow rate (JIS K6730) of 0.1 to 70 g / 10 minutes, preferably 0.8 to 20 g / 10 minutes. Containing ethylene-vinyl acetate copolymer, (b) saponified ethylene-vinyl acetate copolymer having vinyl acetate content of 10 to 70% by weight, preferably 15 to 50% by weight, and (c) tackifier. It is necessary to use an adhesive composition.

If a vinyl acetate content of less than 8% by weight is used as the component (a), sufficient adhesive strength cannot be obtained even if other conditions are satisfied. When the vinyl acetate content exceeds 42% by weight, pellet blocking and the like occur, making it difficult to handle the pellet. Further, if the melt flow rate deviates from the above range, the moldability and the adhesive strength are lowered.

As the component (b), a saponified ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 70% by weight is used, and the saponification degree is 5 to 100%, preferably Is suitably 30 to 60%. This vinyl acetate content is less than 10% by weight,
When the one having a saponification degree of less than 5% is used, the adhesive strength to the ethylene-vinyl alcohol copolymer becomes low.

In the present invention, as the tackifier used as the component (c) of the adhesive layer, an aliphatic hydrocarbon resin, an alicyclic hydrocarbon resin, an aromatic hydrocarbon resin, a polyterpene resin, a rosin Examples thereof include styrene resins and styrene resins. Examples of the aliphatic hydrocarbon resin include
Examples of alicyclic hydrocarbon resins such as 1-butene, isobutylene, butadiene, and polymers containing C4-5 mono- or di-olefins as main components such as 1,3-pentadiene include Spent C ₄ To a resin obtained by polymerizing a diene component in a C ₅ fraction after cyclization and dimerization, a resin obtained by polymerizing a cyclic monomer such as cyclopentadiene, a hydrogenated dicyclopentadiene resin, and an aromatic hydrocarbon resin. Examples of aromatic hydrocarbon resins such as internally hydrogenated resins include resins containing vinyltoluene, indene, vinyl aromatic hydrocarbons having 9 carbon atoms such as α-methylstyrene as a main component,
Examples of the polyterpene-based resin, α-pinene polymer,
Examples of rosins such as β-pinene polymer, dipentene polymer, terpene-phenol copolymer, α-pinene-phenol copolymer are rosin, polymerized rosin, hydrogenated rosin, rosin glycerin ester and its hydrogenated Examples of styrenic resins, such as compounds or polymers, rosin pentaerythritol ester and hydrogenated products or polymers thereof,
Examples thereof include styrene-based monomers and vinyltoluene-α-methylstyrene copolymers. Among these various tackifiers, an alicyclic hydrocarbon resin is preferable in terms of color tone, odor and the like.

In the adhesive composition used as the adhesive layer of the present invention, the above-mentioned components are added in an amount of 30 to 90 parts by weight of component (a) and 5 to 40 parts of component (b) based on 100 parts by weight of the adhesive composition. It is necessary to mix in a ratio of 5 parts by weight and 5 to 30 parts by weight of tackifier. The amount of component (a) is 3
If it is less than 0 parts by weight, the adhesive strength to each resin layer will be reduced, and if the amount of the component (b) is less than 5 parts by weight, ethylene-
The adhesive strength to the vinyl alcohol copolymer decreases, and when it exceeds 40 parts by weight, the adhesive strength to other thermoplastic resins decreases. On the other hand, when the compounding amount of the component (c) is less than 5 parts by weight, the adhesive strength to the ethylene-vinyl alcohol copolymer is lowered, and when it is more than 30 parts by weight, the melt viscosity of the entire composition is lowered and Sex becomes insufficient.

If desired, the adhesive composition used in the present invention may further contain an antioxidant, a lubricant, a weathering stabilizer, a plasticizer, a filler, an antistatic agent, a pigment, a dye, an antifogging agent, an antiblocking agent, A nucleating agent, an organic peroxide, etc. can be contained in an amount within the range where the characteristics are not impaired.

This adhesive composition comprises (a) component, (b)
It is prepared by uniformly kneading a predetermined amount of the component, the component (c) and the desired component.

This kneading can be carried out by using a Henschel mixer, a conical blender, a V blender or the like according to a conventional method, but for more uniform kneading,
It is preferable to use a single-screw or multi-screw extruder, a kneader, a Banbury mixer, a roll kneader, or the like.

The laminate of the present invention can be produced by integrally extrusion-molding the barrier layer, the adhesive layer and the thermoplastic resin layer by, for example, a co-extrusion method. The blow-molding method or the co-injection molding method can be used. Can be used for molding, or can be molded by using an extrusion lamination method.

The laminate of the present invention has at least one combination of barrier layer / adhesive layer / thermoplastic resin layer in its laminated structure, and in addition to that, two or more combinations of various thermoplastic resins. It may include a laminated structure having a combination of layers.

Therefore, examples of the laminate of the present invention include those having the following structures. In the following structural examples, AD is an adhesive layer, EVOH is an ethylene-vinyl alcohol copolymer layer, PS is a polystyrene layer, PP is a polypropylene layer, NY is a nylon layer,
PET is an abbreviation for polyethylene terephthalate layer, and PC is an abbreviation for polycarbonate layer.

(A) PS / AD / EVOH / AD / PS (b) PS / AD / PP / AD / EVOH / AD / PP
/ AD / PS (C) PS / AD / EVOH / AD / PP (D) PS / AD / EVOH / AD / NY (V) PS / AD / EVOH / AD / PC (F) PS / AD / EVOH / AD / PET (to) PS / AD / EVOH (h) PS / AD / EVOH / AD

In the above (a), PS having good thermoformability and rigidity is provided with a barrier property, and (b) and (c) are those obtained by further imparting moisture resistance to (a), (d) ) Is a product with chemical resistance and abrasion resistance, and (e) is a base layer made of P
C changed to C, (F) changed the base layer to PET,
(G) is an example in which EVOH is used as a surface layer to impart aroma and chemical resistance, and (H) is an example in which AD is attached to the surface to enable adhesion to another object.

The laminate of the present invention can be formed into not only a multilayer sheet, but also a film, a pipe, a block, or any other desired shape. In particular, a shape suitable for use as a packaging material or a food container can be obtained. Is advantageous. Further, when the cover material is composed of base material / EVOH / sealant container inner surface layer is a thermoplastic resin, EVOH /
It can also be used advantageously as a sealant / thermoplastic structure.

[0024]

EXAMPLES The present invention will be described in more detail with reference to examples.

The physical properties in each example are evaluated according to the following criteria. (1) Sheeting property: Using 3 to 5 extruders equipped with a feed block and a T-die, a multilayer laminate was manufactured, and the moldability in the coextrusion sheet molding line was examined and evaluated according to the following criteria. .

⊚: No peeling was observed in the line, and no peeling occurred even if the sample was extremely bent. ◯: No peeling is observed in the line, but peeling occurs if the sample is extremely bent. ×: Partial peeling was observed even in the line, and it was completely peeled off when extreme bending was applied.

(2) Hot-filling property: Shown by the maximum limit temperature at which peeling does not occur when the contents are filled at 70 ° C. or higher. (3) Container characteristics: The multilayer laminate obtained in (1) is CM-6
Using a 333-type molding machine, vacuum pressure molding was performed to create a container having a expansion ratio of 2 and a caliber of 80 mm, and bending stress was applied to observe the presence or absence of peeling. . (4) Peel strength; at a tensile speed of 300 mm / min,
It is expressed as the force required for 180 degree peeling (kgf / 15 mm). (5) Comprehensive evaluation; ○ is a container suitable for a comprehensive judgment, Δ is a container that can withstand practical use, and X is a container that cannot be used.
And

Reference Examples 1 to 3 Ethylene-vinyl acetate copolymer [Tosoh Corporation, trade name Ultrasen 627, vinyl acetate content 20% by weight,
Melt flow rate 0.8 g / 10 minutes, density 0.940
g / cm ³ ] and saponified ethylene-vinyl acetate copolymer (vinyl acetate content before saponification: 28% by weight, saponification degree: 4
0%, melt flow rate 16 g / 10 min, density 0.9
5 g / cm ³ ) and alicyclic hydrogenated petroleum resin [Arakawa Chemical Co., Ltd., trade name Alcon P125, ring and ball softening point 12]
5 ° C., bromine number 2] in a ratio shown in Table 1, mixed by a V blender, and then kneaded and granulated using a 40 mm diameter single screw extruder (full flight screw) at a set temperature of 180 ° C. while cooling the screw. , Adhesive composition AD ₁
The ~AD ₃ was prepared.

Next, these adhesive compositions were mixed with an ethylene-vinyl alcohol copolymer [Kuraray Co., Ltd., trade name Kuraray Eval EP-E, ethylene content 44 mol%, melt flow rate 5.5 g]. / 10 minutes, density 1.1
4 g / cm ³ ] and two-layer cast molding under the following conditions to produce a laminate of an adhesive layer (outer layer) 20 μm and an ethylene-vinyl alcohol copolymer layer (inner layer) 50 μm.

Extruder: Outer layer 20 mmφ extruder, tip temperature 210 ° C. Inner layer 25 mmφ extruder, tip temperature 200 ° C. T-die set temperature; 210 ° C. line speed; 8 m / min

90% between the adhesive layer and the ethylene-vinyl alcohol copolymer layer in the thus obtained laminate
Table 1 shows the interfacial peel strength of the peeling.

Reference Examples 4,5 Saponification products of ethylene-vinyl acetate copolymer having a saponification degree of 20% and a melt flow rate of 15 g / 10 minutes,
Or saponification degree 80%, melt flow rate 16g / 10
Adhesive compositions (AD ₄ and AD ₅ ) were prepared in the same manner as in Reference Example 1 except that the above components were used. Table 1 shows the peel strength of the laminate with the ethylene-vinyl alcohol copolymer produced in the same manner as in Reference Example 1.

Reference Example 6 An adhesive composition was prepared in the same manner as in Reference Example 1 except that an ethylene-vinyl acetate copolymer having a vinyl acetate content of 26% by weight and a melt flow rate of 2.4 g / 10 min was used. (AD ₆ ) was prepared. Table 1 shows the peel strength of the laminate with the ethylene-vinyl alcohol copolymer produced in the same manner as in Reference Example 1.

Reference Example 7 Reference Example 1 except that an ethylene-vinyl acetate copolymer having a vinyl acetate content of 6% by weight, a melt flow rate of 2.5 g / 10 minutes and a density of 0.927 g / cm ³ was used.
An adhesive composition (AD ₇ ) was prepared in the same manner as in. Table 1 shows the peel strength of the laminate with the ethylene-vinyl alcohol copolymer produced in the same manner as in Reference Example 1.

Reference Examples 8 to 11 As an adhesive composition, a saponified ethylene-vinyl acetate copolymer having a saponification degree of 40%, a melt flow rate of 16 g / 10 minutes and a density of 0.95 g / cm ³ was used. A laminate with an ethylene-vinyl alcohol copolymer was produced in the same manner as in. The peel strength of this product is shown in Table 1.

[0036]

[Table 1]

Using the adhesive compositions obtained in Examples 1 to 5 and Comparative Examples 1 and 2, a laminate having the structure shown in Table 2 was produced by coextrusion, and the results of evaluation of the physical properties are shown in Table 2. Shown in.

The material abbreviations used in each example have the following meanings. PP ₁ ... Idemitsu Petrochemical Co., Ltd. trade name Idemitsu Polypropylene F-205S PS ₁ ... Idemitsu Petrochemical Co., Ltd. trade name Idemitsu Polystyrene ET-60 PS ₂ ... Philips Oil Company trade name K Resin K
R-03 EVOH ₁ ... Made by Kuraray Co., Ltd. Product name Eval EP-
E105 EVOH ₂ ... Made by Kuraray Co., Ltd. Trade name Eval EP-
T102 NY ₁ ... Ube Industries, Ltd. product name UBE Nylon 6 1023FD1 PC ₁ ... Idemitsu Petrochemical Co., Ltd. product name Tufflon A3
000 PET ₁ ... Product name PET-G manufactured by Kodak
6763

[0039]

[Table 2]

In this table, those of Comparative Examples 1 and 2 are
Although it has a problem in physical properties and cannot be put to practical use, those of Examples 1 to 5 have sufficient adhesive strength and satisfy other required properties.

Application Example A container body was produced using a laminate having the structure shown in Table 3 produced in the same manner as in the example, and a laminate comprising polyethylene terephthalate, barrier EVOH ₁ and sealant AD ₃ or AD ₇ was used as the lid material. Table 3 shows the peel strength when used in combination as.

[0042]

[Table 3]

As is clear from this table, No. 1 to N
o. No. 5 can be used as a container, but No. 6
~ No. No. 8 cannot be used because the lid material peels off during transportation or immediately after sealing.

[0044]

EFFECTS OF THE INVENTION The present invention is a laminate in which a barrier layer and a thermoplastic resin base layer are firmly adhered to each other, and when a container is manufactured using this, peeling does not occur when the sealed lid material is removed, Further, it is possible to provide a material having excellent barrier properties and surface characteristics that do not cause delamination during transportation or long-term use.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taro Yamashita 3778-2 Nishisakabe-cho, Yokkaichi-shi, Mie

Claims (4)

[Claims] 1. A laminate comprising a structure in which a barrier layer is laminated with another thermoplastic resin layer via an adhesive layer, wherein (A)
The barrier layer is composed of an ethylene-vinyl alcohol copolymer, and the (B) adhesive layer has a vinyl acetate content of 8 to 42% by weight and a melt flow rate of 0.1 to 70 g / 10 min. 90 parts by weight, vinyl acetate content of 10 to 70% by weight, saponification degree of 5 to 100% of ethylene-vinyl acetate copolymer 5 to 40 parts by weight, and tackifier of 5 to 30 parts by weight to a total amount of 100 parts by weight. A gas barrier laminate, comprising an adhesive composition formulated as follows. 2. The gas barrier laminate according to claim 1, wherein the ethylene-vinyl alcohol copolymer has an ethylene content of 25 to 50 mol% and a melt flow rate of 0.5 to 25 g / 10 minutes. 3. The gas barrier laminate according to claim 1, wherein the thermoplastic resin layer has a melt flow rate of 0.5 to 25 g / 10 minutes. 4. The thermoplastic resin layer comprises polyethylene, polypropylene, polystyrene, polycarbonate, polyamide or polyethylene terephthalate.
The gas barrier laminate according to 2 or 3.