JPS606457A - Cylindrical laminated film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Low density polyethylene resins have been used in many fields due to their excellent mechanical properties and transparency.

However, the film obtained by molding low-density polyethylene resin by the commonly used inflation molding method, that is, the top-blown air-cooled inflation method, does not have sufficient transparency. When using fat, the film becomes a film with a marked decrease in transparency.

Therefore, in order to solve this drawback, a method was proposed in which the extruded material was rapidly cooled by the downward water-cooling inflation method. However, although transparency is improved according to this method, there are disadvantages in that the blocking resistance of the obtained film is deteriorated and the opening property is also reduced. Therefore, the amount of antiblocking agent added must be increased, which inevitably has a negative effect on transparency. Further, in this method, the transparency of the film improves as the cooling is performed more quickly, but there is also the essential and serious drawback that the film curls significantly inward. This curling causes problems such as reduced handling and printing workability during processing and cutting, as well as poor appearance due to distortion of products such as bags.

As described above, a cylindrical film with excellent transparency, good opening properties, blocking resistance, etc., and less curling has not yet been put into practical use.

Therefore, the inventors of the present invention conducted extensive research to develop a film with the above-mentioned properties. As a result, a cylindrical laminated film containing a specific resin in its inner and outer layers has excellent transparency, opening properties, anti-blocking properties, etc. The present invention was completed based on the knowledge that curling was also reduced.

That is, the present invention has a density of 0.900 to 0.9509/c.
This is a cylindrical laminated film formed of an outer layer made of an ethylene polymer of "RRT" and an inner layer made of a polyolefin polymer having a melting point higher than that of the ethylene polymer.

In the present invention, the outer layer has a density of 0.900 to 0.95.
0 g, 73, preferably 0.91O to 0.940g/
cyt” is used.The density is 0.9.
If it is less than 007A-ffL3, blocking resistance will deteriorate, and if it exceeds 0.950 g or 43, transparency will deteriorate, which is not preferable. The ethylene polymer for the outer layer may have a density within the above range, but generally has a melt index (Mx) of 0.5 to 20 to 710.
minutes are used.

Examples of the ethylene polymer include ethylene homopolymers as well as copolymers of ethylene and other α-olefins. Specifically, high-pressure low-density polyethylene, medium-density polyethylene, copolymers of ethylene and α-olefin having 3 to 12 carbon atoms, i.e., linear low-density polyethylene (for example, ethylene-butene- 1 copolymer, ethylene-4-methylpentene-1 copolymer, f (combination, ethylene-ofufane-1 copolymer, etc.).

A copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms is preferred;
A copolymer containing 5 wt% is preferably used. The melting point of high-pressure low-density polyethylene is usually 100 to 120°C, and the melting point of medium-low pressure ethylene-α-olefin co-educated composite is usually 110 to 130°C.

Next, in the present invention, a polyolefin polymer having a higher melting point than the ethylene polymer of the outer layer is used as the inner layer. Examples of polyolefin polymers include propylene homopolymers, copolymers of propylene and ethylene or α-olefins having 4 to 12 carbon atoms (α-olefin content: 1
5% by weight or less) and high-density polyethylene (ethylene homopolymer or copolymer of ethylene and α-olefin having 3 to 12 carbon atoms) with a density of 0.940 to 0.970 l/cry. .The difference in melting point depends on the type of resin used,
It may be selected appropriately considering the layer thickness ratio of the inner and outer layers, the molding method, etc., but usually the difference is 5 to 50"C1, preferably &!10C or more.

Various additives such as stabilizers (antioxidants, thermal decomposition inhibitors, etc.), anti-blocking agents, slip agents, colorants, fillers, etc. may be added to the inner and outer layers as necessary to the extent that they do not impair the purpose of the present invention. It is possible to apply a force t. Further, a crystal nucleating agent can be added to the polyolefin polymer of the inner layer. Here, the crystal nucleating agent regulates the crystal nucleation rate of the polyolefin polymer and accelerates the crystallization rate.
It has the effect of suppressing the size of crystals. Specifically, metal salts of organic acids such as benzoic acid, cyclohexanecarbo/acid, diphenylacetic acid, etc. are used as organic crystal nucleating agents.
innicotinic acid, adipic acid, sepacic acid, phthalic acid,
Magnesium such as benzenesulfonic acid and glycolic acid,
Metal salts of calcium, sodium, aluminum, titanium, etc.; amine salts of organic O, such as benzoic acid, phthalic acid.

Examples include amines derived from adipic acid and the like.

Further, as the inorganic nucleating agent, fine powder of silica, alumina, talc, etc. is used.

Other a-fat layers may be laminated between the inner and outer layers or on the outside of both layers as long as the purpose of the present invention is not impaired. The cylindrical laminated film of the present invention can be produced by various molding methods. For example, after melt-kneading each material and extruding it through a circular die, it is manufactured by a bottom-blown water-cooled inflation molding method, a top-blown air-cooled inflation molding method, a bottom-blown spray-cooled inflation molding method, etc., especially a bottom-blown water-cooled inflation molding method. is preferred. These inflation moldings are usually carried out at a blow ratio of 0.8 to 3.0, preferably 1.1 to 2.5.

Also, the layer ratio of the outer layer and inner layer is outer layer: inner layer = 50:50
-97:3, preferably 60:40-95:5. If the thickness of the inner layer exceeds 50%, the properties of the ethylene polymer as a film are lost. Moreover, if it is less than 3%, molding becomes difficult and it becomes impossible to obtain a film that does not cause curling.

Since the cylindrical laminated film of the present invention uses materials for the inner and outer layers that satisfy specific conditions, the solidification of the inner layer will not be much slower than that of the outer layer even if it is rapidly cooled during inflation molding. , 7 (No curling occurs in the film. Therefore, it has excellent moldability and is excellent in workability in secondary processing such as bag making and printing. In addition, this film has extremely good transparency and is free from blocking. In addition, it has good physical properties such as balan 7 and maintains flexibility, which is a characteristic of low-density polyethylene.

Therefore, the cylindrical private layer film of the present invention is suitable for clothing.

It is extremely useful as a packaging material for foods, miscellaneous goods, etc.

Next, the present invention will be explained in detail with reference to examples.

Examples 1 to 10 The resins for the inner layer and outer layer shown in Table 1 were each supplied to two extruders (50 uφ, L//D=2d) and melt-kneaded. Next, a circular die with internal adhesive (150 m
iφ, grip-rip interval 2 mm) and extruded downward, followed by bottom-blown water-cooled inflation molding at a blow ratio of 1.3 (
A cylindrical coextruded laminated film having a thickness of 40 μm was obtained by cooling directly externally with cooling water at a temperature of 25° C. The melting point was measured using a scanning pyrolysis apparatus (DSO) and in accordance with ASTM D-34.
17, the peak temperature was defined as the melting point after an endothermic calculation. Table 1 shows the results of measuring the physical properties of the obtained film.

Comparative Example A monolayer film was produced using the resins shown in Table 1 according to the example. The results are shown in Table 1.

*1 ・-ethylene-octene-1 copolymer, density 0
．． 927 knots/cm3. MI 4.9/10 minutes, melting point 125°C *2...Ethylene-4-methylpentene-1 copolymer, density 0,9259/crn3. MI 2,4ri/
10 minutes.

Melting point 124℃ *3...Ethylene-octene-1 copolymer, density 0
．． 940 li/ca", MI 4.0 li/1o min, melting point 126°C Season 4...High pressure low density polyethylene, density 0.92
09A-IIL3. MI 2.1/10 minutes, melting point 1
11.4℃*5 ...Polypropylene, density 0.91
9/cm3. MI8.0/10 minutes, melting point 170'C *6...°Random polypropylene, density o, 90
g/cm3. RlI 7.09/10 min, melting point 15
5°C *7 - High density polyethylene, density 0.95
59/cm".

MI O8059/10 minutes, melting point 132℃*8 ・=J
Conforms to IS Z 1702 *9-JIS P 8134
Compliant with *] 0...Film impact method (The film was fixed in a ring shape, and the film was struck with a pendulum with a 1-inch impact head, and the energy required was measured. Using a film impact tester manufactured by Toyo Seiki Seisakusho. ) *11... Based on ASTM D 1003 *12...
- Based on ASTM D 523 *13: The obtained cylindrical film was judged visually.

◎・・・No curls at all ○...Slightly curly ××・・・curls violently

Claims (1)

[Scope of Claims] (]) An outer layer made of an ethylene polymer having a density of 0.900 to 0.95 oti/ctna and an inner layer made of a polyolefin polymer having a melting point higher than that of the ethylene polymer. A cylindrical laminated film. (2) The cylindrical laminated film according to claim 1, wherein the layer ratio of the outer layer to the inner layer is from 50:50 to 97:3. (3) Ethylene polymer has ethylene and carbon number 3 to 12
The cylindrical laminated film according to claim 1, which is a copolymer of α-olefin. (4) The cylindrical laminated film according to claim 1, wherein the polyolefin polymer is a polypropylene polymer.