JPH11245342A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a non-polyvinyl chloride laminated film which is good at flexibility, processability, and the balance of strength, and does not generate harmful gas in incineration. SOLUTION: In a laminated film constituted at least from both outer layers and an intermediate layer, the intermediate layer consists of a block copolymer mainly containing at least one vinyl aromatic hydrocarbon block and at least one block mainly consisting of a conjugated diene or its hydrogen adduct, and both outer layers consist of a polyethylene resin. The ratio of the total thickness of both layers to that of the intermediate layer is 1:0.2-50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film having excellent balance between flexibility, processability and strength.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of protection of the global environment, films that do not generate harmful gas have been used instead of vinyl chloride resins that generate harmful gas when incinerated. However, conventional PVC replacement films are
Compared to films made of vinyl chloride resin, flexibility,
There is a drawback that workability is inferior, and improvement thereof is strongly desired. In addition, it is pointed out that the tensile elongation at break is small particularly in applications requiring flexibility. For example, JP-A-61-106645 and JP-A-2-4846 describe polyethylene-based plastic films made from a mixture of an ethylene-ethylenically unsaturated ester copolymer and polyethylene. In this system, the tensile elongation at break was not sufficient.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an excellent non-vinyl chloride laminated film which is excellent in balance of flexibility, processability and strength and which does not generate harmful gas even when incinerated. is there.

[0004] The inventors of the present invention have intensively studied to obtain a non-PVC film having excellent performance, and the intermediate layer is composed of a specific block copolymer, and both outer layers are composed of polyethylene resin. The inventors have found that a laminated film having at least three layers achieves the object of the present invention, and have completed the present invention.

[0005]

That is, the present invention is directed to a laminated film comprising at least both outer layers and an intermediate layer, wherein the intermediate layer comprises at least one vinyl aromatic hydrocarbon polymer block and at least one vinyl aromatic hydrocarbon polymer block. A block copolymer (A) or a hydrogenated product thereof (A ′) comprising a plurality of conjugated diene-based polymer blocks,
Both outer layers are layers made of polyethylene resin (B),
The thickness ratio of the intermediate layer is 0.2 to 50 with respect to the total thickness 1 of both outer layers. Hereinafter, the present invention will be described in detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The laminated film of the present invention is a laminated film having at least three layers composed of both outer layers and an intermediate layer. The intermediate layer is composed of at least one vinyl aromatic hydrocarbon polymer block and at least one conjugated diene-based polymer block (A) or a hydrogenated product thereof (A ′). It is a layer composed of Here, the polymer block mainly composed of a conjugated diene is a polymer block having a conjugated diene content of 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. In the polymer block mainly composed of a conjugated diene, a vinyl aromatic hydrocarbon may be copolymerized, and the vinyl aromatic hydrocarbon may be uniformly distributed in the polymer. They may be distributed in a par. The weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene in the block copolymer is not particularly limited, but is, for example, 30:70 to 55:45, preferably 30:70.
70 to 50:50.

[0007] Examples of the above-mentioned vinyl aromatic hydrocarbon include styrene, o-methylstyrene, p-methylstyrene, pt-butylstyrene, α-methylstyrene and the like. These may be used alone or in combination of two or more. A particularly common one is styrene. The conjugated diene is a diolefin having a pair of conjugated double bonds.
Butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene,
Examples thereof include 3-pentadiene and 1,3-hexadiene. These may be used alone or in combination of two or more. Particularly common are 1,3-butadiene,
Isoprene. In addition, the block copolymer (A) used in the present invention can be used as a hydrogenated product (A ′) obtained by hydrogenation in an inert solvent, if desired.

Specific examples of the block copolymer (A) or its hydrogenated product (A ') include styrene-butadiene-styrene block copolymer (SBS) and styrene-isoprene-styrene block copolymer. (SI
S), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS) and the like. Among them, styrene-butadiene-styrene block copolymer (SBS) is preferable.

Further, the intermediate layer may further contain various resins, if necessary, as long as the effects of the present invention are not impaired. For example, to further improve workability,
A polyethylene resin may be contained.

Both outer layers are layers composed of a polyethylene resin (B). Polyethylene resin is ethylene-
A resin composition containing the ethylenically unsaturated ester copolymer (b1) is preferred. As the polyethylene resin (B), a resin composition containing the ethylene-ethylenically unsaturated ester copolymer (b1) and the polyethylene (b2) is more preferable in terms of processability. The mixing ratio of the ethylene-ethylene unsaturated ester copolymer (b1) and the polyethylene (b2) is not particularly limited,
For example, it is 10:90 to 90:10 parts by weight. Examples of the ethylenically unsaturated ester include vinyl acetate or an α, β-unsaturated carboxylic acid alkyl ester. The α, β-unsaturated carboxylic acid alkyl ester includes an unsaturated carboxylic acid having 3 to 8 carbon atoms, such as an alkyl (meth) acrylate, and specific examples thereof include methyl acrylate and ethyl acrylate. N-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate,
Examples include n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, and isobutyl methacrylate. Among these, vinyl acetate, methyl acrylate, ethyl acrylate, n-butyl acrylate and methyl methacrylate are preferred, and methyl methacrylate is particularly preferred.

The polyethylene (b2) is not particularly limited, but examples thereof include low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and linear ultra-low-density polyethylene. In addition, polyethylene (b2)
The melt flow rate (MFR) is 0.02-
Polyethylene having a density of 0.850 to 0.945 g / cm ³ and a melt flow rate (MFR) of 0.02 to 5 g / 10 minutes are more preferable. In particular, the polyethylene resin (B)
Repeating units derived from ethylenically unsaturated esters (hereinafter referred to as "ethylenically unsaturated ester units")
10 to 40% by weight, melt flow rate (MF
R) A resin containing an ethylene-ethylenically unsaturated ester copolymer (b1) of 0.5 to 40 g / 10 min and a polyethylene (b2) of a melt flow rate (MFR) of 0.02 to 5.0 g / 10 min. The resin composition has a content of ethylenically unsaturated ester units of 7
-25% by weight, and more preferably a resin composition having an MFR ratio of the component (b1) / (b2) of 1 to 120.

In order to further improve the physical properties of the intermediate layer and both outer layers of the present invention, 2,6-di-t-butyl-
p-cresol (BHT), tetrakis [methylene-3
-(3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (IRGANOX 101
0), n-octadecyl-3- (4'-hydroxy-
Phenolic stabilizers represented by 3,5'-di-t-butylphenyl) propionate (IRGANOX 1076); bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, tris (2,4 −
Phosphite stabilizers represented by di-t-butylphenyl) phosphite; lubricants represented by higher fatty acid amides and higher fatty acid esters; glycerin esters, sorbitan acid esters and polyethylene glycol esters of fatty acids having 8 to 22 carbon atoms Anti-static agents such as calcium stearate; processability improvers represented by fatty acid metal salts such as calcium stearate; and anti-blocking agents represented by silica, calcium carbonate, talc and the like.

The resin components and additives such as antioxidants, anti-blocking agents, lubricants, and processability improvers to be blended according to various purposes may be melt-kneaded in advance and then subjected to film processing. Dry blending or one or more master batches may be used for film processing after dry blending, and any method may be used.

In the laminated film of the present invention, the thickness ratio of the intermediate layer is 0.2 to 5 with respect to the total thickness of the two outer layers.
0, preferably 0.5 to 20, more preferably 1 to 5. If this ratio is too low, the flexibility is poor, and if it is too high, the heat resistance is poor.

In order to produce the laminated film of the present invention, techniques such as a co-extrusion method and an extrusion coating method (also referred to as an extrusion lamination method) are generally employed using an inflation film production apparatus or a T-die film production apparatus. can do. Further, using the multilayer or single-layer film obtained by using these apparatuses, a desired multilayer film is produced by a known technique such as a lamination method such as a dry lamination method, a wet lamination method, a sand lamination method, and a hot melt lamination method. You can also.

[0016]

Hereinafter, the present invention will be described based on examples.
The present invention is not limited to these examples. The evaluation method was performed as follows. (1) Density (d) According to the method specified in JIS K6760. (2) Melt flow rate (MFR) The MFR of the polyethylene resin was measured at 190 ° C under a load of 2.16 kg according to the method specified in JIS K6760. MFR of block copolymer is 200 ℃, 5kg
It was measured by load. (3) Content of methyl methacrylate unit A press sheet was prepared, and the absorbance of characteristic absorption in the infrared absorption spectrum was corrected for thickness, and the content was determined by a calibration curve method. As characteristic absorption, methyl methacrylate
The peak at 50 cm ^-1 was used. (4) Processability Film processing was performed using three 30 mmφ granulators and three types of three-layer T dies, and the processability at this time was evaluated. The point of evaluation was the state of sticking to the chill roll.
The thickness of the film was 80 μm, the set temperature of the extruder was 150 ° C. in a cylinder, 170 ° C. in a die, the take-up speed was 5 m / min, the die width was 250 mm, the chill roll was a mirror roll, and the roll temperature was 20 ° C. (5) Tensile breaking strength and tensile breaking elongation The method specified in JIS K6781 was used. (6) 100% elongation strength (flexibility) According to a method specified in JIS K6781, when a tensile test was performed, the strength at a point where the elongation between chucks became 100% was measured. The smaller the value, the better the flexibility.

Example 1 As the polyethylene resin (B), low-density polyethylene produced by high-pressure radical polymerization (density 0.922 g / cm ³ , M
FR 0.3 g / 10 min) 30 wt%, ethylene-methyl methacrylate copolymer (methyl methacrylate unit content 25 wt%, MFR 7.0 g / 10 min) 70 wt%, and 100 parts by weight of the two components of the resin , Heat stabilizer 2
00 ppm, lubricant 1200 ppm and silica 8000 p
A resin composition obtained by melt-kneading and granulating pm with a twin-screw extruder was used. The MFR ratio of this resin composition was 23.3, and the content of methyl methacrylate units was 18% by weight.
As the block copolymer (A), a styrene-butadiene-styrene block copolymer (DEXCO P
OLYMER SBS, VECTOR 6241D, styrene unit content 40% by weight, MFR 23 g / 10
Min). Three 30mmφ using these resins
Two types and three layers of coextruded films were produced with an extruder. The layer configuration is (B) / (A) / (B) = 10 μm / 60 μm / 10
μm, and the thickness ratio of the intermediate layer to the total thickness of both outer layers was 1. Table 1 shows the evaluation results of this film.

COMPARATIVE EXAMPLE 1 A single-layer film made of only the same polyethylene resin (B) as that used in Example 1 was prepared without using the block copolymer (A). The thickness of the film was 80 μm. Table 1 shows the results.

Comparative Example 2 A single-layer film processing of only the same block copolymer (A) as used in Example 1 was performed without using the polyethylene resin (B). Could not be made.

[0020]

[Table 1]

[0021]

As described above, according to the present invention, it is possible to provide a laminated film having a better balance of flexibility, processability and strength than conventionally known films. The laminated film can be suitably used for miscellaneous goods such as stationery. Further, the above laminated film is suitable for medical use such as a bandage after laminating an adhesive.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08L 23:08 25:10

Claims (7)

[Claims] 1. A laminated film comprising at least both outer layers and an intermediate layer, wherein the intermediate layer is mainly composed of at least one vinyl aromatic hydrocarbon polymer block and at least one conjugated diene. A layer comprising a block copolymer (A) comprising a block or a hydrogenated product thereof (A '), wherein both outer layers are layers comprising a polyethylene resin (B), and the thickness ratio thereof is the total thickness of both outer layers 1. A laminated film, wherein the thickness of the intermediate layer is from 0.2 to 50 with respect to 1. 2. The method according to claim 1, wherein the polyethylene resin (B) is ethylene-
The laminated film according to claim 1, which is a resin composition containing an ethylenically unsaturated ester copolymer (b1). 3. The method according to claim 1, wherein the polyethylene resin (B) is ethylene-
The laminated film according to claim 1, which is a resin composition containing an ethylenically unsaturated ester copolymer (b1) and polyethylene (b2). 4. The polyethylene resin (B) has a content of a repeating unit derived from an ethylenically unsaturated ester of 1
0-40% by weight, melt flow rate (MFR) 0.5
Ethylene-ethylenically unsaturated ester copolymer (b1) and melt flow rate (MFR) of ４０40 g / 10 min
A resin composition containing polyethylene (b2) having a content of 0.02 to 5.0 g / 10 minutes, and a content of a repeating unit derived from an ethylenically unsaturated ester in the resin composition is 7 to 25% by weight. %, And the MFR ratio of the component (b1) / the component (b2) is from 1 to 120.
The laminated film according to the above. 5. The laminated film according to claim 2, wherein the ethylenically unsaturated ester is an alkyl (meth) acrylate. 6. The polyethylene (b2) has a density of 0.850.
The laminated film of claim 3 or 4, wherein wherein the ~0.945g / cm ^3. 7. The laminated film according to claim 1, wherein the block copolymer (A) is a styrene-butadiene-styrene block copolymer (SBS).