JPH07369B2 - Laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminate having excellent gas permeation resistance, moisture permeation resistance, mechanical strength, interlayer adhesion and the like. More specifically, it relates to a laminate comprising an oleophine layer and a polyvinylidene chloride layer.

[Conventional technology]

Polyolefin films represented by polyethylene film and polypropylene film are excellent in heat sealing property, mechanical strength and water resistance, and are lightweight, non-toxic, tasteless and odorless, and thus are most often used as a film for food packaging. However, on the other hand, it has relatively high gas permeability such as oxygen and carbon dioxide gas, and is slightly inferior in oil resistance and grease resistance. Therefore, it is not suitable for foods such as fish meat, meat or processed products thereof that easily perish or oily foods. It has the drawback that it cannot be used by itself. As a method for improving this drawback, it has been proposed to laminate polyvinylidene chloride excellent in gas permeability resistance and oil resistance, and a saponified product of ethylene / vinyl acetate copolymer, but since polyolefin does not have a polar group. However, even if they are directly laminated with these resins, the interlayer adhesive strength is very low and they cannot be put to practical use.

As a method for improving the interlayer adhesion between the polyolefin layer and the polyvinylidene chloride layer, a method of using a modified polyolefin in which an unsaturated carboxylic acid or a derivative thereof is grafted as the polyolefin (JP-B-57-14970)
Has been proposed and has been effective. However, in recent years, there has been a demand for a laminate having further improved interlayer adhesion depending on the use, and it has been found that the proposed method is partially insufficient.

[Problems to be solved by the invention]

In view of such a situation, the present inventors have variously studied to obtain a laminate composed of a polyolefin layer and a polyvinylidene chloride layer having excellent gas permeation resistance, moisture permeation resistance, mechanical strength, interlayer adhesion, etc. It was found that the above object can be achieved by using a modified product obtained by graft-modifying a low crystalline or amorphous ethylene / α-olefin random copolymer as a layer with an unsaturated carboxylic acid or a derivative thereof, and the present invention was completed. It came to do.

[Means for solving problems]

That is, in the present invention, (a) a polyolefin (A) layer and (b) an intermediate layer, an unsaturated carboxylic acid or a derivative thereof is grafted in an amount of 0.1 to 50% by weight, and a melt flow rate is 0.01 to 50 g / 10 m.
In-modified ethylene polymer (B ₁ ) 1 to 20% by weight Melt flow rate graft-modified with unmodified or unsaturated carboxylic acid or its derivative: 0.1 to 50 g / 10
min, density: 0.850 to 0.900 g / cm ³ , ethylene content: 30
To 95 mol% and an X-ray crystallinity: 40% or less of an ethylene / α-olefin random copolymer (B ₂ ) 99 to 80% by weight, and the composition (B). B) is an unsaturated carboxylic acid or its derivative grafted: 0.01
To 10% by weight, melt flow rate: 0.1 to 50 g / 10
min, density: 0.850 to 0.900 g / cm ³ , ethylene content: 30
To 95 mol% and a degree of crystallinity by X-ray: 40% or less, the composition (B) layer, and (c) a polyvinylidene chloride (C) layer. Gas permeability,
It is intended to provide a laminate having excellent moisture resistance, mechanical strength, interlayer adhesion and the like.

[Work]

The polyolefin (A) constituting the laminate of the present invention is
Ethylene, propylene, 1-butene, 1-hexene, 4
-Homopolymers of α-olefin such as methyl-1-pentene, copolymers of α-olefins, or copolymers of α-olefin with vinyl compounds such as vinyl acetate, vinyl chloride, methyl methacrylate and styrene. And
Specifically, for example, high pressure method low density polyethylene (HP-LDP
E), medium / low pressure low density polyethylene (so-called L-LDP
E), ethylene / 1-butene random copolymer, ethylene / propylene random copolymer, polypropylene (P
P), propylene random copolymer, propylene block copolymer, propylene / ethylene random copolymer,
Propylene / 1-butene random copolymer, poly-1-butene, 1-butene / propylene copolymer, poly-4-methyl-1-pentene, ethylene / vinyl acetate copolymer (EV
A), ethylene-ethyl methacrylate copolymer (EEA)
Etc. These polyolefins (A) are usually melt flow rate: MFR (polypropylene containing propylene as a main component is ASTM D 1238: L, 4-methyl-1-
Pentene-based polyolefins have a load of 5 kg, temperature of 260 ° C, ethylene-based polyolefins and other polyolefins have ASTM D 1238, E) of 0.01 to 200 g / 10 min, preferably 0.1 to 100 g / 10 min. It is a thing.

The modified ethylene polymer (B ₁ ) that constitutes the intermediate layer (B) of the laminate of the present invention is a graft amount of unsaturated carboxylic acid or its derivative of 0.1 to 50% by weight and a melt flow rate of 0.01 to 50 g / 10 min, usually a homopolymer of ethylene with a density of 0.98 to 0.90 g / cm ³ and a crystallinity by X-ray of 90 to 40% or ethylene and a small amount of other α
-Olefins such as propylene, 1-butene, 4-
Methyl-1-pentene, 1-hexene, 1-octene,
It is a copolymer mainly composed of ethylene with 1-decene or the like.

Similarly, an ethylene-α-olefin random copolymer graft-modified with an unmodified or unsaturated carboxylic acid or a derivative thereof constituting the intermediate layer (B) of the laminate of the present invention (hereinafter, these are collectively referred to as modified Abbreviated to random copolymer) (B ₂ ), modified ethylene-α-
The olefin random copolymer is a graft amount of unsaturated carboxylic acid or its derivative of 0.01 to 10% by weight, preferably 0.1 to 5% by weight, and a melt flow rate (MFR).
(L): ASTM D 1238, L) 0.1 to 50 g / 10 min, preferably 0.2 to 20 g / 10 min, density 0.850 to 0.900 g / cm
³ , preferably 0.855 to 0.895 g / cm ³ , an ethylene content of 30 to 95 mol%, preferably 40 to 92 mol% and a crystallinity by X-ray of 40% or less, preferably 30% or less part or It is a graft-modified ethylene / α-olefin random copolymer which is wholly graft-modified.

If the graft amount of the unsaturated carboxylic acid or its derivative in the composition of the intermediate layer is less than 0.01% by weight, the adhesiveness with polyvinylidene chloride (C) will not be improved, while if it exceeds 10% by weight, it will be partially crosslinked. And the moldability tends to be poor.

If the MFR (L) is outside the above range, the melt viscosity will be too high or too low, resulting in poor moldability. Density is 0.
Polyvinylidene chloride (C) with 900 g / cm ³ , ethylene content of 92 mol% and crystallinity of more than 40% by X-ray
The adhesive strength with is poor. Further, those having an ethylene content of less than 30 mol% also have poor adhesion to polyvinylidene chloride (C).

The α-olefin which constitutes the modified random copolymer (B ₂ ) of the present invention is usually α-olefin having 2 to 20 carbon atoms, specifically, for example, propylene, 1-butene, 1-hexene, 4-methyl. -1-pentene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene, etc.,
Each is composed of a single compound or a mixture of two or more compounds.

The modified random copolymer (B ₂ ) of the present invention is, as described above, a low crystalline or amorphous modified polyolefin, and the low crystalline copolymer usually has a melting point (STMA D 3418) of 100.
It is below ℃.

The ethylene / α-olefin random copolymer that is the base of the modified random copolymer (B ₂ ) used in the present invention is usually
MFR (L) 0.1 to 50g / 10min, density 0.850 to 0.
It is a random copolymer of ethylene and α-olefin with 900 g / cm ³ , an ethylene content of 30 to 95 mol% and a crystallinity by X-ray of 40% or less, preferably 30% or less.

The ethylene / α-olefin random copolymer is
The unsaturated carboxylic acid or derivative thereof
Acrylic acid, maleic acid, fumaric acid, tetrahydrofuran
Talic acid, itaconic acid, citraconic acid, crotonic acid, iso
Crotonic acid, nadic acid (Endocis-bicyclo [2,
2,1] hept-5-ene-2,3-dicarboxylic acid)
Saturated carboxylic acids, or their derivatives, such as acid halide
, Amides, imides, anhydrides, esters, etc.
Specifically, maleenyl chloride, maleimide, maleic anhydride
In-acid, citraconic anhydride, monomethyl maleate,
Examples include dimethyl oleate and glycidyl maleate.
Be done. Among these, unsaturated dicarboxylic acids or their
Acid anhydrides are preferred, especially maleic acid and nadic acid.
Alternatively, these acid anhydrides are suitable.

In order to produce a modified product by graft-copolymerizing a graft monomer selected from the unsaturated carboxylic acid or its derivative with the random copolymer, various conventionally known methods can be adopted. For example, there is a method in which the random copolymer (E) is melted and a graft monomer is added to perform graft copolymerization, or a method in which the random copolymer (E) is dissolved in a solvent and the graft monomer is added to perform graft copolymerization. In any case, it is preferable to carry out the reaction in the presence of a radical initiator in order to efficiently graft-copolymerize the graft monomer. The grafting reaction is usually performed at a temperature of 60 to 350 ° C. The proportion of the radical initiator used is usually in the range of 0.001 to 1 part by weight per 100 parts by weight of the random copolymer. Examples of the radical initiator include organic peroxides, organic peresters, and other azo compounds. Among these radical initiators, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di ( Dialkyl peroxides such as tert-butylperoxy) hexane and 1,4-bis (tert-butylperoxyisopropyl) benzene are preferred.

The graft-modified ethylene / α-olefin random copolymer (B ₂ ) used in the present invention may be partially diluted with the ethylene / α-olefin random copolymer, but in that case, unsaturated carboxylic acid, etc. It is necessary that the total graft amount of the above is within the above range.

Further, the modified random copolymer (B ₂ ) used in the present invention contains
Within the range that does not impair the object of the present invention, heat stabilizers, weather stabilizers, antistatic agents, nucleating agents, pigments, dyes and the like, various compounding agents usually used by adding to polyolefins, the polyolefin (A), inorganic A filler, an adhesive, a styrene resin, polyvinylidene chloride, polyurethane, an acrylic resin, a nitrile resin, a polyester resin, a polyamide resin, and wax may be blended in advance.

The polyvinylidene chloride (C) constituting the laminate of the present invention is a copolymer of vinylidene chloride as a main component and vinylidene chloride and acrylonitrile, vinyl chloride, an acrylic ester or a methacrylic ester.

The composition (B) of the present invention comprises a modified ethylene polymer (B ₁ ) and an unmodified or modified ethylene / α-olefin random copolymer (B ₂ ) as long as the properties of the resulting composition are within the above range. The amount of the modified ethylene polymer (B ₁ ) is usually 1 to 20% by weight, preferably 2 to 10% by weight, although the amount thereof is not particularly limited.

The composition (B) of the present invention is used by adding it to ordinary polyolefin such as heat resistance stability, weather resistance stability, antistatic agent, nucleating agent, pigment, dye, etc. within a range that does not impair the object of the present invention. You may mix | blend various compounding agents or the polyolefin (A), an inorganic filler, an adhesive, a styrene resin, polyvinylidene chloride, polyurethane, an acrylic resin, a nitrile resin, a polyester resin, a polyamide resin, and wax which are mentioned.

The laminate of the present invention is composed of a polyolefin (A) layer / a modified random copolymer (B) layer / a polyvinylidene chloride (C) layer, and such (A) / (B) / (C) is a basic structure. As long as it is, (A) / (B) / (C) / (B) /
It may be the structure of (C). Also, the repro layer (D)
(A) / (D) / (B) / (C), (A) /
(D) / (B) / (C) / (B) / (A) and (A)
The structure may be / (D) / (B) / (C) / (B) / (D) / (A). Further, of course, a structure in which (B) is changed to the composition (J) may be used.

As a method for producing the laminate of the present invention, various known methods,
For example, if the laminate is in the form of a film or sheet, oliolefine (A), composition (B) and polyvinylidene chloride (C) are melted by separate extruders and fed to a three-layer structure die, A method of co-extruding the composition (B) as an intermediate layer, forming a polyolefin (A) layer and a polyvinylidene chloride (C) layer in advance, and forming the composition (B) between the layers (A) and (C). ) Is melt-extruded, the so-called Germany delamination method, in which a preformed polyvinylidene chloride (C) layer is melted with a polyolefin (A) and a composition (B) by separate extruders and laminated from a die having a two-layer structure. A so-called co-extrusion laminating method in which a film is extruded and laminated is exemplified. If the laminate has a bottle, barrel, pipe, or tube shape, a coextrusion method may be used. Further, when the polyolefin (A) layer or the polyvinylidene chloride (C) layer is previously formed, the layer may be uniaxially or biaxially stretched.

The thickness of each layer of the laminate of the present invention can be variously determined according to the use, but in the case of a film or a sheet, a polyolefin (A) layer is 5 to 3000 μm and a composition (B) layer is 2 to 1000 μm.
μ, and the polyvinylidene chloride (C) layer is preferably in the range of 2 to 1000 μ.

〔The invention's effect〕

The laminate of the present invention has water resistance, heat sealability, mechanical characteristics, food hygiene characteristics that are characteristic of polyolefin, and gas permeation resistance, oil resistance, moisture resistance that is characteristic of polyvinylidene chloride, and has interlayer adhesion. Since it has excellent properties, durability and hygiene, it can be used as a packaging material for foods, pharmaceuticals and the like.

〔Example〕

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Comparative Example 1 Maleic anhydride graft-modified ethylene / propylene random copolymer (MAH-EPR-1; MFR (L) 0.5 g / 10 min, density 0.865 g / cm ³ , ethylene content 80 mol%, crystallinity 4
%, Maleic anhydride graft ratio 0.5 g / 100 g polymer) was used to prepare a 150 μ sheet by compression molding, and then 150 μ polyvinylidene chloride (PVDC) was applied to both outer surfaces of the sheet.
-1) [Dow Chemical (USA), trade name: SARAN, X05253-16] layer and 150μ high pressure low density polyethylene (HP-LDPE-1); MFR (E) 6.0g / 10min, density 0.920 g / cm ³ ) layer so that the intermediate layer is the MAH-EPR-1 layer, and the temperature is 230
PVDC by heat-bonding at ℃, time 3 seconds, pressure 1kg / cm ^2.
A three-layer laminate composed of −1 / MAH-EPR-1 / HP-LDPE-1 was prepared. A test piece with a width of 15 mm was cut out from this three-layer laminate, and PVDC-1 layer, MAH-EPR-1 layer and MAH-EPR-1 layer were cut.
The interlayer adhesive strength between the HP-LDPE-1 layer and the HP-LDPE-1 layer was measured by performing a T-peel test (peel rate 300 mm / min, measurement temperature 23 ° C.). The results are shown in Table 1.

Comparative Example 2 Instead of MAH-EPR-1 used in Comparative Example 1, maleic anhydride graft-modified ethylene / 1-butene random copolymer (MAH-EBR-1; MFR (L) 6.0 g / 10 min, density 0.885 g / c
Example 3 was repeated except that m ³ , crystallinity 16%, ethylene content 90 mol%, maleic anhydride graft ratio 0.5 g / 100 g-polymer) were used. The results are shown in Table 1.

Comparative Example 3 Instead of MAH-EPR-1 used in Comparative Example 1, maleic anhydride graft-modified ethylene / propylene random copolymer (MAH-EPR-2; MFR (L) 1.8 g / 10 min, density 0.864 g / cm
^3. Crystallinity 4%, ethylene content 80 mol%, maleic anhydride graft ratio 0.1 g / 100 g-A polymer was used in the same manner as in Comparative Example 1 except that a polymer was used. The results are shown in Table 1.

Comparative Example 4 Instead of MAH-EPR-1 used in Comparative Example 1, 50 parts by weight of MAH-EPR-1 used in Comparative Example 1 and MAH-E used in Comparative Example 2 were used.
The same procedure as in Comparative Example 1 was carried out except that a modified mixture obtained by melt mixing BR-1 (50 parts by weight) was used. The results are shown in Table 1.

Comparative Example 5 Instead of MAH-EPR-1 used in Comparative Example 1, 50 parts by weight of MAH-EPR-1 used in Comparative Example 1 and an ethylene / propylene random copolymer (EPR-3; MFR (L)) were used. 3.5g / 10min, density 0.
864 g / cm ³ , crystallinity 4%, ethylene content 80 mol%: 50
The same procedure as in Comparative Example 1 was carried out except that a modified mixture obtained by melt-mixing 1 part by weight of the mixture was used. The results are shown in Table 1.

Example 1 Instead of MAH-EPR-1 used in Comparative Example 1, 95 parts by weight of EPR-3 used in Comparative Example 5 and maleic anhydride graft-modified polyethylene (MAH-PE-1; MFR (E) 4.3) were used. g / 10min, density
0.962 g / cm ³ , crystallinity 72%, butene content 0.5 mol%,
Mixed modified product (MFR (L)) obtained by melt mixing 5% by weight of maleic anhydride graft ratio of 2.2 g / 100 g-polymer)
3.6g / 10min, density 0.869g / cm ³ , crystallinity 7%, ethylene content 81mol%, maleic anhydride graft ratio 0.11g / 100g
Polymer was used in the same manner as in Comparative Example 1. The results are shown in Table 1.

Comparative Example 6 Instead of HP-LDPE-1 used in Comparative Example 1, a propylene-ethylene random copolymer (MFR (L) 6.3 g / 10 min,
The procedure of Comparative Example 1 was repeated except that the ethylene content was 4 mol%). The results are shown in Table 1.

Example 2 90% by weight of MAH-EPR-1 used in Comparative Example 1 and 10 parts by weight of MAH-PE-1 used in Example 1 were melt mixed to obtain a mixed modified product (MFR (L) 0.63 g / 10min, density: 0.875g / c
m ^3, crystallinity of 11%, an ethylene content of 82 mol%, in the same manner except for using the graft ratio 0.67 g / 100 g-polymer of maleic anhydride) and Comparative Example 1 KoTsuta. The results are shown in Table 1.

Comparative Example 7 Instead of MAH-EPR-1 used in Comparative Example 1, ethylene.
Propylene random copolymer (MFR (L) 0.6g / 10min,
The procedure of Comparative Example 1 was repeated except that the density was 0.864 g / cm ³ , the crystallinity was 4%, and the ethylene content was 80 mol%). The results are shown in Table 1.
Shown in.

Comparative Example 8 Instead of MAH-EPR-1 used in Comparative Example 1, maleic anhydride graft-modified polyethylene (MFR (L) 2.1 g / 10 mi
n, density 0.955 g / cm ³ , crystallinity 65%, maleic anhydride graft ratio 0.3 g / 100 g-polymer) Comparative Example 1
I went as well. The results are shown in Table 1.

Claims (1)

[Claims] 1. A graft layer of an unsaturated carboxylic acid or its derivative: 0.1 to 50% by weight, a melt flow rate: 0.01 to 50 g / 10 m, as (a) a polyolefin (A) layer and (b) an intermediate layer.
In-modified ethylene polymer (B ₁ ) 1 to 20% by weight Melt flow rate graft-modified with unmodified or unsaturated carboxylic acid or its derivative: 0.1 to 50 g / 10
min, density: 0.850 to 0.900 g / cm ³ , ethylene content: 30
To 95 mol% and an X-ray crystallinity: 40% or less of an ethylene / α-olefin random copolymer (B ₂ ) 99 to 80% by weight, and the composition (B). B) is an unsaturated carboxylic acid or its derivative grafted: 0.01
To 10% by weight, melt flow rate: 0.1 to 50 g / 10
min, density: 0.850 to 0.900 g / cm ³ , ethylene content: 30
To 95 mol% and the degree of crystallinity by X-ray: 40% or less, the composition (B) layer, and (c) a polyvinylidene chloride (C) layer. .