JPH0124068B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a copolymer of ethylene and an α,β-unsaturated carboxylic acid or a metal salt thereof and a copolymer of ethylene and an α,β-unsaturated carboxylic acid.
-Relating to a laminate comprising an olefin copolymer and having excellent interlayer adhesion, transparency, and moisture permeability. Copolymers of ethylene and α,β-unsaturated carboxylic acids or their metal salts, especially ionomers, have low-temperature heat-sealing properties, hot-tack properties, oil resistance,
Laminated films with ionomer heat-sealing layers are used as various packaging materials because of their excellent adhesion to nylon and metals. However, even though ionomers have excellent properties as mentioned above, they are hygroscopic and have poor moisture permeability.
When packaging items that contain moisture or that deteriorate due to moisture absorption, it is necessary to use a material that is laminated with a material that is highly resistant to moisture absorption. Materials with excellent moisture absorption resistance include metal materials such as aluminum foil, polyolefin, etc. However, although laminated films with aluminum foil have improved moisture absorption resistance, they lack transparency, which is one of the characteristics of ionomers. Unable to utilize
It is not suitable for packaging applications where you want to show the contents. on the other hand,
Although the laminate with polyolefin had excellent transparency, it had poor interlayer adhesion and there was a risk of interlayer peeling during use. Ethylene/vinyl acetate copolymers are known to have relatively good interlayer adhesion with ionomers, but they have poor water vapor permeability and odor, so they have low practical value. As a method for improving the interlayer adhesion between an ionomer and a polyolefin, a method has been proposed in which polyolefin is added to the ionomer and then laminated with the ionomer.However, although this method improves the interlayer adhesion to some extent, it does not reduce the transparency. loss,
Since bumps and gels are produced during film molding, it is not always possible to obtain a laminate that is of practical value. A method has also been proposed in which an ethylene-propylene copolymer rubber is interposed between the ionomer and the polyolefin, but it has been difficult to obtain strong adhesive strength because the copolymer rubber has low mechanical strength. Therefore, the present inventors conducted research to improve the interlayer adhesion between a copolymer of ethylene and an α,β-unsaturated carboxylic acid or a metal salt thereof, and a polyolefin. It was found that by using a copolymer of α-olefin having 3 to 20 carbon atoms, a laminate having excellent interlayer adhesion, transparency, and moisture permeability can be obtained, and the present invention was achieved. That is, the present invention provides a copolymer of ethylene and α,β-unsaturated carboxylic acid or a metal salt thereof (A) layer with a density of 0.910 to less than 0.940 g/cm ³ and a crystallinity of 48 to 62% by X-rays. The object of the present invention is to provide a laminate comprising a copolymer (B) layer of less than or equal to ethylene and an α-olefin having 3 to 20 carbon atoms. The copolymer of ethylene and α,β-unsaturated carboxylic acid or its metal salt (A) used in the present invention is:
Usually 0.2 α,β-unsaturated carboxylic acid is added to ethylene.
The metal salt is an ionic copolymer in which part or all of the carboxylic acid is cross-linked with a metal ion having a valence of 1 to 3. It is. Copolymerized with ethylene. Specifically, α,β-unsaturated carboxylic acids include acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, maleic acid,
Monoesters of fumaric acid and dicarboxylic acids, such as monomethyl maleate, monomethyl fumarate, monoethyl fumarate, and the like. In addition, metal ions having a valence of 1 to 3 and used for cross-bonding (neutralizing) α,β-unsaturated carboxylic acids refer to metal ions with a valence of 1 to 3 in groups such as -A and in the periodic table of the elements. It is a metal ion having a valence of, specifically, for example,
Na ⁺ , K ⁺ , Li ⁺ , Cs ⁺ , Ag ⁺ , Hg ⁺ , Cu ⁺ , Be,
Mg, Ca, Sr, Ba, Cu, Cd, Hg
, Sn, Pb, Fe, Co, Ni, Zn,
Al, Sc, Fe, Y, etc. Further, the degree of neutralization by metal ions is usually at least 5% or more, preferably 10 to 60%. The ethylene/α-olefin copolymer (B) used in the present invention has a density of 0.910 to less than 0.940 g/cm ³ ,
Preferably less than 0.920 to 0.930 g/cm ³ , X-ray crystallinity of 48 to less than 62%, preferably 50
or less than 57% and preferably has a melting point of 110 or more
It is a copolymer with an α-olefin having 3 to 20 carbon atoms, preferably 6 to 18 carbon atoms, at a temperature of 126°C, more preferably 115 to 123°C. The ethylene/α-olefin copolymer (B) having the above properties used in the present invention is obtained by polymerizing ethylene and α-olefin in a ratio to obtain the required density by a so-called medium-low pressure method using a transition metal catalyst. It can be obtained by letting In this case, a molecular weight regulator such as hydrogen may be used to obtain the desired melt flow rate. Polymerization can be carried out by various methods such as slurry polymerization, gas phase polymerization, and high temperature solution polymerization. Density less than 0.910g/ ^cm3 and crystallinity
If it is less than 48%, although it has adhesion to the copolymer of ethylene and α,β-unsaturated carboxylic acid or its metal salt (A), its mechanical strength is low, resulting in weak adhesion and poor durability. It also has poor moisture permeability. density is
Those with a crystallinity of 0.940 g/cm ³ and 62% or more have poor adhesion. In addition, the density in this invention is ASTM
This is a value measured using D1505. The melting point of the copolymer (B) was determined from the endothermic curve measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C/min.
It is the highest temperature among one or more endothermic peaks, often two or three. melting point
Those below 110°C have poor heat resistance, and those above 126°C have poor adhesive properties. The α-olefin having 3 to 20 carbon atoms to be copolymerized with ethylene in the copolymer (B) includes propylene, 1-butene, 1-pentene, 1-hexene,
1-heptene, 4-methyl-1-pentene, 1-
Octene, 1-decene, 1-tetradecene, 1-
Examples include octadecene or a mixture of at least two thereof. So-called high-pressure low-density polyethylene, which is a homopolymer of ethylene and has a low density, has poor adhesion or adhesive force between ethylene and α,β-unsaturated carboxylic acid or its metal salt (A). The copolymer of ethylene and α,β-unsaturated carboxylic acid or its metal salt (A) and copolymer (B) may optionally contain a weathering stabilizer, a heat stabilizer, an antistatic agent, Various compounding agents such as anti-fogging agents, anti-blocking agents, slip agents, lubricants, pigments, dyes, etc., which are usually added to polyolefins, etc., and other polyolefins may be blended within the range that does not impair the purpose of the present invention. You can leave it there. When the laminate of the present invention is in the form of a film or sheet, the laminate is prepared by first adding ethylene, α,
After forming a film or sheet of β-unsaturated carboxylic acid copolymer or its metal salt (A) or copolymer (B),
A method of extrusion lamination of α,β-unsaturated carboxylic acid copolymer or its metal salt (A), ethylene/
A method of coextruding α, β-unsaturated carboxylic acid copolymer or its metal salt (A) and copolymer (B) from a multilayer die, ethylene α-β-unsaturated carboxylic acid copolymer or metal It can be obtained by stacking films or sheets of salt (A) and copolymer (B) and melting and pressurizing them. If the laminate is in the shape of a bottle, barrel, pipe, or tube, it can be obtained by coextrusion. Among these, coextrusion molding is preferred because a laminate with excellent interlayer adhesion can be easily obtained. The thickness of each layer of the laminate of the present invention is not particularly limited, but the ethylene/α,β-unsaturated carboxylic acid copolymer or its metal salt (A) layer and the copolymer (B)
The layer thickness is usually 5 to 500μ, preferably 10
It ranges from 100μ to 100μ. The laminate of the present invention has low-temperature heat-sealing properties, hot-tack properties, oil resistance, and transparency of the ethylene/α,β-unsaturated carboxylic acid copolymer or its metal salt (A) layer, and the copolymer (B) layer. Because it does not impair its moisture permeability and transparency, and has excellent interlayer adhesion, it is used as a packaging material in all fields, including watery products, high-moisture products, oil-based products, and products containing water and oil. be able to. In addition, the laminate of the present invention may further include non-stretched, uniaxially or biaxially stretched low-density polyethylene, high-density polyethylene, polypropylene, polyester, polyamide, polyvinyl alcohol, ethylene/vinyl alcohol copolymer,
Various materials having excellent moisture permeability or gas permeation resistance, such as polyvinyl chloride or polyvinylidene chloride layers, may be laminated. In this case, polyolefins such as low-density polyethylene can be laminated with a copolymer (B) layer, and if polyamide is laminated with an ionomer layer, a laminate with excellent interlayer adhesion can be obtained without an adhesive. A modified polyolefin may also be used. Next, the present invention will be explained 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. Example 1 From an extruder (30 mmφ), ethylene content was 85 mol%, neutralization degree was 59%, and mel flow rate was 1.2 g/
10min (ASTM D1238:E) Na salt of ethylene methacrylic acid copolymer (trade name: Himilan)
1707, manufactured by Mitsui Polychemical Co., Ltd. (hereinafter abbreviated as EM-Na) was heated at 230℃ using an extruder (40 mmφ) to produce an ethylene/α-olefin copolymer (B) at a melt flow rate of 2 g/10 min (ASTM D1238:
E), density 0.921g/cm ³ , crystallinity by X-ray 51%
and melting point 123℃ (there are other peaks at 119℃ and 104℃)
After melting each of the ethylene/4-methyl-1-pentene copolymer (hereinafter abbreviated as EMP-) at 230℃,
Supplied to a two-layer circular die (resin temperature 230℃), a two-layer film (inner layer: EM-Na/outer layer: EMP-=30μ/
30μ) was obtained. Next, the physical properties of the film were evaluated by the following method. Initial interlayer adhesion strength: From the film, width 15mm x length
A 100mm test piece was taken, and the layers were peeled off at a peeling speed of 300mm/min using the T-peel method using an Instron tensile tester.
It was determined from the average value of the required strength. Interlayer adhesive strength after boiling: After the film was boiled in hot water at 80°C for 1 hour, interlayer adhesive strength was determined in the same manner as above. Heat seal strength: Using a heat sealer manufactured by Toyo Seiki Co., Ltd., heat seal the inner layers at 2 kg/cm ² × 1 sec at a temperature of 140°C, then peel off the heat sealed portion at a peeling speed of 300 mm/min to determine the required strength. The average value was taken as the heat seal strength. Haze: ASTM D1003 Moisture permeability: Temperature 40°C, humidity 90% by cup method
It was conducted based on JIS Z0208 under RH conditions. The results are shown in Table 1. Examples 2 to 6 Instead of the EMP used in Example 1, each melt flow rate was 2 g/10 min, density 0.910 g/
cm ³ and crystallinity 49% ethylene 4-methyl-1
-Pentene copolymer (hereinafter abbreviated as EMP-), melt flow rate 2g/10min, density 0.915g/
cm ³ and crystallinity 50% ethylene 4-methyl-1
-Pentene copolymer (hereinafter abbreviated as EMP-), melt flow rate 3g/10min, density 0.926g/
cm ³ and crystallinity 52% ethylene 4-methyl-1
-Pentene copolymer (hereinafter abbreviated as EMP-), melt flow rate 2g/10min, density 0.930g/
cm ³ and crystallinity 54% ethylene 4-methyl-1
-Pentene copolymer (hereinafter abbreviated as EMP-V), melt flow rate 2g/10min, density 0.936
Ethylene/4-methyl-1-pentene copolymer (hereinafter abbreviated as EMP-) with g/cm ³ and crystallinity of 58%
The same procedure as in Example 1 was carried out except that . The results are shown in Table 1. Comparative Examples 1 to 3 Instead of EMP used in Example 1, each melt flow rate was 2 g/10 min, density 0.905 g/
cm ³ and crystallinity 47% ethylene 4-methyl-1
-Pentene copolymer (hereinafter abbreviated as EMP-), melt flow rate 2.7g/10min, density 0.940g/
cm ³ and crystallinity 62% ethylene 4-methyl-1
-Pentene copolymer (hereinafter abbreviated as EMP-), melt flow rate 6g/10min, density 0.945
Ethylene/4-methyl-1-pentene copolymer (hereinafter abbreviated as EMP-) with g/cm ³ and crystallinity of 65%
The same procedure as in Example 1 was carried out except that . The results are shown in Table 1. Examples 7 to 9 Instead of EMP used in Example 1, each melt flow rate was 3 g/10 min, density 0.921 g/
cm ³ and crystallinity of 49% ethylene-propylene copolymer (hereinafter abbreviated as EPC), melt flow rate 3
g/10min, density 0.921g/ ^cm3 and crystallinity 48%
Ethylene-1-butene copolymer (hereinafter abbreviated as EBC) with a melt flow rate of 2 g/10 min, a density of 0.921 g/cm ³ and a crystallinity of 51%.
The same procedure as in Example 1 was carried out except that the -octene copolymer (hereinafter abbreviated as EOC) was used. The results are shown in Table 1. Comparative Examples 4 and 5 Instead of EMP used in Example 1, each melt flow rate was 2 g/10 min, density 0.921 g/
cm ³ and crystallinity 51% high pressure low density polyethylene (hereinafter abbreviated as HPPE) and melt flow rate 2.5
g/10min, density 0.940g/ ^cm3 and crystallinity 36%
The same procedure as in Example 1 was carried out except that the ethylene/vinyl acetate copolymer (hereinafter abbreviated as EVA) was used.
The results are shown in Table 1. Examples 10 and 11 Instead of EM-Na used in Example 1, the melt flow rate was 4.5 g/10 min and the density was 0.940 g/1.
cm ³ , ethylene content 91 mol%, neutralization degree 15% Zn salt of ethylene/methacrylic acid copolymer (hereinafter referred to as EM-
(abbreviated as Zn) and melt flow rate 15g/
10min, density 0.940g/ ^cm3 and ethylene content 87
Mol% of ethylene methacrylic acid copolymer (hereinafter
Example 1 was carried out in the same manner as in Example 1, except for using EMC (abbreviated as EMC). The results are shown in Table 1. Example 12 EM-Na used in Example 1 as an ionomer was transferred from an extruder (30 mmφ) to an extruder (30 mmφ).
EMP used in Example 1 was melted at 230℃ from a (40mmφ) extruder, and polypropylene (trade name: Mitsui Petrochemical Polypro F600, manufactured by Mitsui Petrochemical Industries, hereinafter abbreviated as PP) was melted from an extruder (40mmφ). After that, it was fed to a three-layer circular die (resin temperature 230°C) and a three-layer film (inner layer: EM-Na/middle layer: EMP-/outer layer: PP=20μ/20μ/20μ) was obtained by water-cooled inflation method. . Performance was then evaluated using the method described in Example 1. The results are shown in Table 1. Example 13 The same procedure as Example 12 was carried out except that HPPE used in Comparative Example 4 was used instead of PP used in Example 12. The results are shown in Table 1. Comparative Examples 6 and 7 The same procedure as in Example 12 was carried out except that EVA used in Comparative Example 4 was used instead of EMP- used in Example 12. The results are shown in Table 1. 【table】

Claims (1)

[Scope of Claims] 1. A copolymer of ethylene and α,β-unsaturated carboxylic acid or a metal salt thereof (A) layer, having a density of 0.910 to less than 0.940 g/cm ³ and a crystallinity of 48 to 48 by X-rays. A laminate comprising a copolymer (B) layer of less than 62% ethylene and an α-olefin having 3 to 20 carbon atoms.