JPH0994934A - Multilayered laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered laminated film showing excellent interlaminar strength, especially, showing excellent bonding strength to a base material film at relatively high temp., for example, at 60 deg.C. SOLUTION: A multilayered laminated film is obtained by laminating a first layer (A) composed of a propylene polymer and at least uniaxially oriented, a second layer (B) composed of a propylene copolymer having an m.p. lower than that of the propylene polymer of the first layer, a third layer (C) composed of a polymer compsn. containing a graft modified olefin polymer to which unsaturated carboxylic acid or a derivative thereof is grafted and a fourth layer (D) composed of an ethylene/vinyl alcohol copolymer in this order.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a multilayer laminated film. More specifically, it relates to a multilayer laminated film comprising a polyolefin layer and an ethylene / vinyl alcohol copolymer layer and exhibiting excellent interlayer adhesion.

[0002]

2. Description of the Related Art Stretched polyolefin films, especially biaxially stretched polypropylene films, are widely used as packaging films because they are inexpensive and have excellent transparency and mechanical strength. However, this polyolefin film has a drawback that it has a poor gas barrier property. In order to improve this drawback, a polypropylene biaxially stretched film has heretofore been coated with an emulsion of polyvinylidene chloride (PVDC) to form a layer, which has been used for applications such as cigarette packaging which require aroma retention. . However, this film can cause problems when incinerated and a replacement was desired.

On the other hand, polar materials such as nylon and ethylene-vinyl alcohol copolymer are known as materials having gas barrier properties, and many laminated films comprising these gas barrier resin layers and polyolefin layers have been proposed. ing. However, in a laminated film in which a polyolefin is stretched, the adhesive strength between these polar materials and the polyolefin is extremely low, which is a level that cannot be put to practical use.

[0004]

SUMMARY OF THE INVENTION The first object of the present invention is to provide a multilayer laminated film having excellent gas barrier properties, transparency and mechanical strength. Another object of the present invention is to provide a laminated film comprising a polyolefin layer and an ethylene / vinyl alcohol copolymer layer and having excellent interlayer adhesion. Another object of the present invention is to provide a laminated film having excellent heat resistance. Still another object of the present invention is to provide a laminated film which is less likely to cause environmental problems during production and which can be easily incinerated or recycled after use. Still another object of the present invention is to
An object of the present invention is to provide a multi-layer laminated film that maintains excellent adhesive strength even at relatively high temperatures such as 60 ° C. Further objects and advantages of the present invention will be apparent from the following description.

[0005]

According to the present invention, the above objects and advantages of the present invention are that (A) at least uniaxially oriented first layer of propylene polymer, (B) first layer of propylene. Second layer comprising a propylene copolymer having a melting point lower than that of the polymer, (C) third polymer comprising a graft modified olefin polymer grafted with an unsaturated carboxylic acid or a derivative thereof The layer and the fourth layer consisting of (D) ethylene vinyl alcohol copolymer are achieved by a multilayer laminated film laminated in this order.

As described above, the multilayer laminated film of the present invention has each of the first to fourth layers. The first layer comprises a propylene polymer and is at least uniaxially oriented. The propylene polymer of the first layer may be a homopolymer of propylene or a copolymer of propylene and the content of other α-olefin of 2 mol% or less with other α-olefin. Other α-olefins include, for example, ethylene, 1-butene, 1-hexene, 4-methyl-1.
-Pentene, 1-octene, 1-decene and the like can be mentioned. As the propylene polymer, a homopolymer of propylene is preferable. As the propylene polymer, A
Melt flow rate (MFR) measured according to STM D1238 (230 ° C, load 2,160g) is 0.0
Those which are 1 to 100 g / min, more preferably 0.1 to 10 g / min are advantageously used.

The first layer is preferably biaxially stretched and oriented. As the biaxial stretching method, various methods known per se can be adopted.

The second layer comprises a propylene copolymer having a melting point lower than that of the propylene polymer of the first layer.
This propylene copolymer includes propylene and other α
-A copolymer with an olefin, in which the propylene content is 80 to 98 mol% is preferable. Other α-
As the olefin, the same ones as described above for the propylene polymer of the first layer can be exemplified. Preferred examples of the propylene copolymer for the second layer include propylene / ethylene random copolymer, propylene / 1-butene random copolymer and propylene / ethylene / 1-butene random copolymer.
These can be used alone or in combination of two or more. The propylene copolymer of the second layer preferably has a melting point of 120 to 140 ° C. Further, this propylene copolymer was prepared according to ASTM D1238 (230 ° C, load 2,16).
Melt flow rate (MFR) measured according to
, Preferably 0.1 to 100 g / min, more preferably 1 to 10 g / min.

The polymer composition of the third layer is characterized by containing a graft-modified olefin polymer grafted with an unsaturated carboxylic acid or a derivative thereof. By containing this graft-modified olefin polymer, it exhibits excellent adhesion to the second layer and the fourth layer. The graft modified olefin polymer is contained in the polymer composition in an amount of preferably 1 to 30% by weight, more preferably 1 to 20% by weight. The graft modified olefin polymer is produced by grafting an unsaturated carboxylic acid or its derivative onto an olefin polymer by a method known per se.
As the olefin polymer before the graft modification, for example, ethylene homopolymer, propylene homopolymer, copolymer of ethylene and other α-olefin, copolymer of propylene and other α-olefin are preferable. Can be mentioned.

The copolymers of ethylene and other α-olefins include ethylene and α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-hexene, 4
-Methyl-1-pentene, 1-octene, 1-decene,
Examples thereof include copolymers with 1-tetradecene, 1-octadecene and the like. The other α-olefin is contained in an amount of preferably 10 mol% or less, more preferably 5 mol% or less. Further, as a copolymer of propylene and other α-olefin, propylene and a carbon number of 2 or 4 to 20
Α-olefins such as ethylene, 1-butene, 1-
Hexene, 4-methyl-1-pentene, 1-octene,
Examples thereof include copolymers with 1-decene, 1-tetradecene, and 1-octadecene. The other α-olefin is again preferably contained at 30 mol% or less, more preferably 10 mol% or less.

As the graft-modified olefin polymer,
Preferably, a graft modified ethylene copolymer, that is, a graft modified product of a copolymer of ethylene and another α-olefin or a graft modified propylene copolymer, that is, a graft modified product of a copolymer of propylene and another α-olefin is used. It is used to advantage.

Examples of the unsaturated carboxylic acid or its derivative include acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid and nadic acid (endocis-bicyclo [2.2. 1] Unsaturated carboxylic acids such as hept-5-ene-2,3-dicarboxylic acid); or derivatives thereof such as acid halides, amides, imides, anhydrides and esters. Specific examples of such derivatives include maleenyl chloride, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate and the like. Of these, unsaturated dicarboxylic acids or acid anhydrides thereof are preferred, and maleic acid, nadic acid or acid anhydrides thereof are particularly preferably used.

The graft-modified olefin polymer graft-modified with the unsaturated carboxylic acid or its derivative is preferably 0.05 based on the olefin polymer before modification.
.About.15% by weight, and more preferably 0.1 to 10% by weight, of the unsaturated carboxylic acid or its derivative. The graft-modified olefin polymer preferably has a melt flow rate (MFR, 230 ° C.) of 0.1.
-50 g / 10 min, more preferably MFR 0.3-30
Indicates g / 10 minutes. Melt flow rate is ASTM D
1238 (190 ° C. for ethylene polymer, 230 ° C. for propylene polymer, load 2,160 g).

The polymer composition of the third layer may contain other polymer in addition to the modified olefin polymer. Preferred examples of the other polymer include polyethylene, polypropylene, ethylene / α-olefin random copolymer, propylene / ethylene random copolymer, ethylene / α-olefin copolymer rubber, and hydrocarbon resin. it can. Of these, ethylene / α with an ethylene content of 95 to 90 mol%
-Olefin random copolymer, specifically ethylene
Preferred examples include propylene random copolymer, ethylene / butene random copolymer and hydrocarbon resin.

Examples of the hydrocarbon resin include petroleum,
C obtained by disassembling naphtha, etc. _FourFraction, C_FiveFraction, this
Mixtures of these or any fractions thereof, such as C_Five
Mainly isoprene and 1,3-pentadiene in the distillate
Aliphatic hydrocarbon resin used as raw material; decomposition of petroleum, naphtha, etc.
C obtained by₉Styrene derivatives and a
Aromatic hydrocarbon resin whose main raw material is nden; C_Four・
C_FiveAny fraction of fraction and C₉Aliphatic and aromatic copolymerized fractions
Aromatic Copolymer Hydrocarbon Resin; Hydrogen Aromatic Hydrocarbon Resin
Added alicyclic hydrocarbon resin; aliphatic, alicyclic and
A synthetic terpene-based hydrocarbon resin having a structure containing an aromatic;
Terpene based on α, β-pinene in turpentine
Hydrocarbon resins; indene and coal tar naphtha
And styrene-based coumarone-indene hydrocarbons
Resin: Low molecular weight styrene resin and rosin hydrocarbon
Resin can be mentioned. Hydrocarbon resin is the third layer
In the combined composition, an amount of 30% by weight or less is advantageously used.
Can be blended.

As the polymer composition of the third layer, 50 to 97% by weight of an ethylene / α-olefin random copolymer having a crystallinity of less than 40% as measured by an X-ray method, and 1 to 20% by weight of a hydrocarbon resin. %, And 1 to 30% by weight of a graft-modified olefin copolymer, and 30 to 93% by weight of a propylene / ethylene random copolymer, ethylene / α.
It is preferably composed of 5 to 40% by weight of olefin copolymer rubber, 1 to 20% by weight of high-pressure polyethylene and 1 to 30% by weight of graft-modified olefin polymer. In the former composition, the graft modified olefin polymer is more preferably a graft modified ethylene polymer. Also,
In the latter composition, the propylene / ethylene random copolymer preferably has an ethylene content of 10 mol% or less,
It is more preferably 5 to 3 mol%. The content is preferably 35 to 70% by weight. In addition, ethylene
The preferable contents of the α-olefin copolymer rubber, the high-pressure polyethylene and the graft-modified olefin polymer are 10 to 35% by weight, 5 to 20% by weight and 2 to 20% by weight, respectively.
% By weight.

The fourth layer comprises an ethylene / vinyl alcohol copolymer. The ethylene / vinyl alcohol copolymer preferably has an ethylene content of 20 to 50 mol%. The ethylene / vinyl alcohol copolymer can be prepared by saponifying ethylene and vinyl acetate copolymer. The ethylene / vinyl alcohol copolymer used in the present invention preferably has a melting point of 130 to 200 ° C.

The multilayer laminated film of the present invention is, for example, the first
A two-layer base film consisting of a layer and a second layer is produced by coextrusion, while a two-layer film consisting of a third layer and a fourth layer is also produced by coextrusion, these two-layer films being in the molten state, By superposing the second layer and the third layer so that they are adjacent to each other, it can be industrially advantageously manufactured. Of course, the first layer, the second layer, the third layer, and the fourth layer are prepared in advance, and these are heated at once to be laminated, or the first layer and the second layer are laminated to obtain It can be manufactured by a method of sequentially laminating each layer, such as laminating a third layer on a laminated sheet and further laminating a fourth layer.

In the multilayer laminated film of the present invention, the first
The thickness of each of the layers, the second layer, the third layer and the fourth layer is 5 to 5, respectively.
It can be in the range of 100 μm, 0.5-10 μm, 0.5-50 μm and 0.5-50 μm. Further, the multilayer laminated film of the present invention is preferably 6.5 to 101.
It has a thickness of 5 μm, especially 10 to 50 μm. The multilayer laminated film of the present invention includes, for example, foods such as fish, meat, dairy products, coffee, tea, cocoa, spices, seasonings and fruits,
It is advantageously used for packaging cigarettes and food additives.
Especially because it has interlayer adhesion even at relatively high temperatures,
It can be used to advantage when used in such a way that the contents are filled before the sealing part is cooled.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples. The invention is in no way limited by these examples.

Example 1 (1) As a polymer composition for forming the third layer, an ethylene / propylene random copolymer (ethylene content 80 mol%, density 0.87 g / cm ³ , MI = 4. 5, X
85% by weight of crystallinity less than 1% measured by the linear diffraction method, aliphatic hydrocarbon resin (manufactured by Arakawa Chemical Industry Co., Ltd., trade name)
Alcon, softening point 125 ° C 10% by weight and maleic anhydride grafted polyethylene (ethylene content 100
%, Graft ratio 2% by weight, MI = 5) 5% by weight, a polymer composition (hereinafter, referred to as polymerization composition A) was prepared.

(2) Polymer composition A and ethylene / vinyl alcohol copolymer (Kuraray Co., Ltd., Eval EP-
L105, hereinafter referred to as EVOH) was supplied to a two-layer extrusion laminator (die width = 500 mm) to obtain a polymer composition A.
A layer (thickness 4 μm) / ethylene / vinyl alcohol copolymer layer (thickness 4 μm) coextruded laminate (thickness 8 μm) was obtained, which was immediately formed into a first layer (A) and a second layer (B). The second layer (B) of the layer base film and the polymer composition A layer were laminated so as to directly overlap each other to produce a four-layer laminated film. The two-layer base film is the first layer (A)
Is a propylene homopolymer (MFR (230 ° C) =
1.2) is a biaxially stretched layer having a thickness of 23 μm, and the second layer (B) is made of a propylene / 1-butene copolymer (1-butene content 15 mol%, melting point 135 ° C.) It is a 2 μm layer. With respect to the obtained four-layer laminate, the adhesive force (g / 15 mm) between the second layer and the third layer and between the third layer and the fourth layer was measured (peel rate 300 mm / m.
in). The results are shown in Table 1.

Example 2 As a polymer composition, an ethylene / 1-butene random copolymer (ethylene content 90%, crystallinity 20% measured by X-ray diffraction method, density 0.88 g / cm ³ , MI =
3.6) 85% by weight, alicyclic hydrocarbon resin (Arakawa Chemical Industry Co., Ltd., trade name Alcon, softening point 125 ° C.) 10
% By weight and polyethylene modified with maleic anhydride (ethylene content 100%, graft rate 2% by weight, MI = 5) 5
A polymer composition B consisting of wt% was prepared. A four-layer laminate was obtained in the same manner as in Example 1 except that the polymer composition B was used in place of the polymer composition A. The adhesive strength of this laminate is shown in Table 1.

Example 3 As a polymer composition, 50% by weight of a propylene / ethylene random copolymer (ethylene content 2 mol%, MI = 20), an ethylene / propylene random copolymer (ethylene content 70 mol%, Density 0.88 g / cm ³ , MI = 4
5) 30% by weight, high-pressure polyethylene (100% ethylene content, density 0.917 g / cm3, MI = 7) 10% by weight and maleic anhydride grafted polypropylene (propylene content 100%, grafting rate 3% by weight, MI =
100) A polymer composition C consisting of 10% by weight was prepared. A four-layer laminate was obtained in the same manner as in Example 1 except that the polymer composition C was used in place of the polymer composition A. The adhesive strength of this laminate is shown in Table 1.

Example 4 As a polymer composition, an ethylene / 1-butene random copolymer (ethylene content 90% by weight, density 0.89 g /
cm ³ , MI = 18) 45% by weight, ethylene-4-methyl-1-pentene copolymer (ethylene content 96% by weight, density 0.920 g / cm ³ , MI = 8) 30% by weight,
High-pressure polyethylene (100% ethylene content, density 0.917 g / cm ³ , MI = 7) 10% by weight, alicyclic hydrocarbon resin (softening point 125 ° C.) 10% by weight and maleic anhydride graft-modified polyethylene ( A polymer composition D having an ethylene content of 100%, a graft rate of 2% by weight, and MI = 5) of 5% by weight was prepared.

In the same manner as in Example 1 except that the polymer composition D was used in place of the polymer composition A in Example 1, 4
A layer stack was obtained. The adhesive strength of this laminate is shown in Table 1.

[0027]

[Table 1]

Comparative Example 1 A three-layer laminate was obtained in the same manner as in Example 2 except that a 20 μm-thick biaxially stretched monolayer film made of propylene homopolymer was used as the base film. The adhesive strength between the first layer and the second layer and between the second layer and the third layer was measured for the obtained three-layer laminate. Table 2 shows the results.

Comparative Example 2 As a base film, a biaxially stretched propylene homopolymer film (MFR (230 ° C.) = 1.2, thickness 20 μm)
A three-layer laminate was obtained in the same manner as in Example 3 except that m) was used. The adhesive strength between the first layer and the second layer and between the second layer and the third layer was measured for the obtained three-layer laminate. Table 2 shows the results
Shown in

[0030]

[Table 2]

Example 5 Four layers were prepared in the same manner as in Example 2 except that a propylene / ethylene random copolymer having a melting point of 147 ° C. (ethylene content 2.3 mol%) was used for the second layer as the base film. A laminated body was obtained. With respect to the obtained four-layer laminate, the adhesive force between the second layer and the third layer and between the third layer and the fourth layer was measured.
The results are shown in Table 3.

[0032]

[Table 3]

[0033]

EFFECT OF THE INVENTION The multi-layer laminated film of the present invention has an excellent interlayer adhesive force and is advantageously used for packaging foods and the like.

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Claims (13)

[Claims] 1. A first layer of (A) a propylene polymer which is at least uniaxially oriented, and (B) a second layer of a propylene copolymer having a melting point lower than that of the propylene polymer of the first layer, (C) Third layer comprising a polymer composition containing a graft-modified olefin polymer grafted with an unsaturated carboxylic acid or a derivative thereof, and (D)
A multilayer laminated film in which a fourth layer made of an ethylene / vinyl alcohol copolymer is laminated in this order. 2. The propylene polymer in the first layer has a propylene homopolymer or other α-olefin content of 2 or less.
The multilayer laminated film according to claim 1, which is a copolymer of mol% or less of propylene and another α-olefin. 3. The multilayer laminated film according to claim 1, wherein the first layer is biaxially oriented. 4. The multilayer laminated film according to claim 1, wherein the propylene content of the propylene copolymer of the second layer is in the range of 80 to 98 mol%. 5. The propylene copolymer of the second layer is a propylene / ethylene random copolymer, a propylene / 1-butene random copolymer or a propylene / ethylene / 1-.
The multilayer laminated film according to claim 4, which is at least one random copolymer selected from the group consisting of butene random copolymers. 6. The propylene copolymer of the second layer is 120-
The multilayer laminated film according to any one of claims 1 to 5, which has a melting point in the range of 140 ° C. 7. The graft-modified olefin polymer in the polymer composition of the third layer is a graft-modified ethylene copolymer or a graft-modified propylene copolymer.
The multilayer laminated film described. 8. The multilayer laminated film according to claim 7, wherein the polymer composition of the third layer contains the graft-modified olefin polymer in a proportion of 1 to 30% by weight. 9. The polymer composition of the third layer comprises 50 to 97% by weight of an ethylene / α-olefin random copolymer having a crystallinity of less than 40% as measured by an X-ray method, and a hydrocarbon resin 1 to
20% by weight and graft-modified olefin polymers 1 to 3
The multilayer laminated film according to claim 8, which comprises 0% by weight. 10. The polymer composition of the third layer is propylene
The ethylene random copolymer 30 to 93% by weight, the ethylene / α-olefin copolymer rubber 5 to 40% by weight, the high pressure polyethylene 1 to 20% by weight, and the graft modified olefin polymer 1 to 30% by weight. Multi-layer laminated film. 11. The multilayer laminated film according to claim 1, wherein the ethylene content of the ethylene / vinyl alcohol copolymer of the fourth layer is 20 to 50 mol%. 12. The first layer, the second layer, the third layer and the fourth layer each have a thickness of 5 to 100 μm, 0.5 to 10 μm,
The multilayer laminated film according to any one of claims 1 to 10, which is in the range of 0.5 to 50 µm and 0.5 to 50 µm. 13. The multilayer laminated film according to claim 12, wherein the total thickness of the first layer, the second layer, the third layer and the fourth layer is in the range of 10 to 50 μm.