JPS6142739B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polypropylene resin composition particularly suitable for producing translucent polypropylene films.

Currently, semitransparent films with rough surfaces mainly composed of polypropylene resin are being actively developed as films for medical, industrial, and food packaging applications.

As a method for manufacturing a translucent film having such a rough surface, there are methods of adding a polyolefin such as polyethylene to polypropylene, adding a blowing agent to polypropylene, or adding a special nucleating agent such as a quinacridone derivative to polypropylene. , a method has been proposed in which a polypropylene sheet having a β-type crystal structure is created by melt molding and then stretched.

These methods either have a narrow range of optimal conditions for obtaining the desired rough surface, require special molding conditions, have a low degree of surface roughening, or are inappropriately balanced with other physical properties. However, there are still some problems, and considerable improvements are needed.

In a co-pending application, the present inventors have proposed that by combining propylene polymers or copolymers (including propylene-ethylene block copolymers), optionally ethylene polymers or copolymers, and organic peroxides, haze, a measure of translucency, can be obtained. It is proposed that films with significantly increased strength can be obtained.

However, it has been found that with the above combination, the resulting product smells of organic peroxide decomposition, which may be undesirable in practice.

Therefore, as a result of intensive studies, the present inventors found that by using a basic inorganic compound in the above composition, not only the decomposition odor of organic peroxide is extremely reduced, but also the haze, which is a measure of translucency, is reduced. The inventors have discovered that the power can be further increased, and have arrived at the present invention.

That is, the present invention provides: A: crystalline polypropylene, crystalline propylene-
At least one type of ethylene block copolymer or crystalline propylene-α-olefin (excluding propylene) copolymer, B: Polyethylene or ethylene as necessary.
(a) At least one copolymer of α-olefin (excluding ethylene) and/or (b) a radically polymerizable polar unsaturated compound, C: The decomposition temperature to obtain a half-life of 10 hours is approximately 60℃
At least one of the above organic peroxides,
and D: consisting of at least one kind of basic inorganic compound of group A metal of the periodic table, and the above component C is 100% of the above component A or (A+B).
A polypropylene composition for producing a translucent polypropylene film, characterized in that the component D is 0.001 to 1.0 parts by weight based on 100 parts by weight of component A or (A+B). It is related to.

A used in the present invention: crystalline polypropylene, crystalline propylene-ethylene block copolymer, or crystalline propylene-α-olefin 1 (excluding propylene) copolymer (α-olefin content 35wt) % or less is preferable)
refers to propylene homopolymers and propylene and other α-olefins such as ethylene, butene-
1, isobutene, hexene-1, 4-methylpentene-1, styrene, etc., or a copolymer with one or more selected from styrene, etc.

B used as necessary in the present invention: polyethylene, ethylene and α-olefin〓2(a)(〓
2 (excluding ethylene) and/or a copolymer with a radically polymerizable polar unsaturated compound (b) [{(a)+
The content of (b)} is preferably 50% by weight or less] means high density polyethylene, medium density polyethylene, low density polyethylene, and ethylene and propylene, butene-1, isobutene, hexene-1, 4-methylpentene-1 , styrene, vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate and the like.

C used in the present invention: The decomposition temperature to obtain a half-life of 10 hours is about 60°C or higher, preferably 60°C.
Organic peroxides with a temperature of ~150°C include lauroyl peroxide, benzoyl peroxide, cyclohexanone peroxide, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoate, methyl ethyl ketone peroxide, dicumyl peroxide, 2, 5-dimethyl 2,5-di(t-butylperoxy)hexane, di-t-butyl peroxide, 2,5-
Dimethyl-2,5-di(t-butylperoxy)
Hexine-3, etc.

The amount of C used is A+ if A or B is added.
The amount is 0.001 to 1 part by weight, preferably 0.005 to 0.5 part by weight, and particularly preferably 0.01 to 0.2 part by weight based on 100 parts by weight of B. If the amount is less than 0.001 weight, no effect of the addition of organic peroxide can be seen. If the amount is more than 1 part by weight, the effect of the addition of the present invention can be seen, but
The melt flow index of the resulting polypropylene composition becomes too high, making it unsuitable for film production.

D: Basic inorganic compound used in the present invention is selected from oxides, hydroxides, carbonates of metals in group A of the periodic table, and basic inorganic compounds containing these as main components, such as magnesium oxide, Examples include calcium oxide, magnesium hydroxide, calcium hydroxide, magnesium carbonate, and calcium carbonate.

The usage amount of D is A when A or B is added.
0.01 to 2.0 parts by weight per 100 parts by weight of +B,
Preferably it is 0.05 to 1.0 parts by weight. If the amount is less than 0.01 part by weight, no effect will be obtained, and if it is added more than 2.0 parts by weight, it may cause staining of the die during film formation, which is not preferable.

The composition of the present invention may also contain various commonly used additives such as stabilizers, antistatic agents, and lubricants, if necessary.

The polypropylene resin composition of the present invention may be used for molding by mixing each raw material in advance and pelletizing it, or by simply feeding the mixture of each raw material directly to a molding machine. I don't mind.

When using the polypropylene resin composition of the present invention, it may be used as it is as an unstretched film, uniaxially or biaxially stretched film, or it may be used as an unstretched polyolefin film or a uniaxially or biaxially stretched polyolefin film. You can laminate it and use it. After laminating the present resin composition on one or both sides of an unstretched polyolefin film, this may be uniaxially or biaxially stretched. Alternatively, the resin composition may be laminated on one or both sides of a uniaxially stretched polyolefin film, and then stretched in a direction perpendicular to the front. Thus, a single film or a laminate film using the polypropylene resin composition of the present invention may be used in an unstretched state or, if necessary, in a uniaxially or biaxially stretched state. A more beautiful and uniformly roughened surface can be obtained by uniaxially or biaxially stretching.

A translucent film made from the resin composition of the present invention, particularly a stretched translucent film, can be used in a wide range of applications as follows.

1. By pasting this film on printed matter, photographs, etc., the shiny appearance can be changed to a calm and calm appearance.

2. When printing is applied to this film, the printed finish has a smooth and calm appearance.

3. By laminating the film with metal foil such as aluminum, you can eliminate the glitter of the metal foil.

4 When a metal such as aluminum is vapor-deposited on a film, a vapor-deposited film with no glitter can be created.

5 This film has good impregnability with oils such as electrical insulating oil, so it is also excellent as an insulating layer for electrical equipment that requires oil impregnation (condensers, transformers, etc.).

6 This film has excellent mold releasability, so it is used as a mold release film when molding unsaturated polyester resins, melamine resins, etc.

7 This film can be heat-sealed, so it can be used to make bags as it is or put it in an automatic packaging machine. Furthermore, when heat is applied to the rough side, only that part becomes transparent, and this can be used to create a patterned film with a mixture of transparent and semi-transparent parts. This transparency can also be achieved by printing on the rough side with colorless ink.

8. If an adhesive tape or adhesive sheet is made by applying an adhesive to one side of this film, the adhesive portion will not be noticeable even when attached to an article. Furthermore, even if you use this tape to repair a torn part of a document, etc. and copy it, the tape will hardly come out on the copying surface, resulting in clean copies.

As described above, the film made of the composition of the present invention has a very wide range of uses and is very useful. The present invention will be explained in more detail with reference to the following examples, but these examples are not intended to limit the present invention.

Example 1 The following composition was mixed uniformly with a mixer, supplied to a pelletizer, and melt-extruded at 230°C to form pellets.

[Composition] A: Propylene-ethylene block copolymer
¹ 90 parts by weight, B: Low density polyethylene ² 10 parts by weight, C: 0.1 part by weight cyclohexanone peroxide, D: 0.1 part by weight magnesium oxide, 1: Ethylene content 20% by weight. ASTM
Melt index measured under condition L of D1238-73: 4.0 g/10 minutes.

2: Melt index 6.2 g/10 minutes measured under ASTM condition E above.

The pellets were fed into an extruder, melt-extruded at 250°C, and laminated on top of a uniaxially stretched polypropylene sheet with a thickness of approximately 160 μm, resulting in a total thickness of approximately
It was made into a 180 μm two-layer laminated sheet. This sheet was set on a film stretcher manufactured by TMLong, and was uniaxially stretched 7 times in the direction perpendicular to the stretching direction of the base polypropylene sheet while heating to 147°C. The obtained film was a clear translucent film and exhibited a haze value of 63% (the haze was measured by measuring one film according to the method of ASTM D 1003-61).

For comparison, I made a film in exactly the same way using the above composition without magnesium oxide, component D, but this film had a faint peroxide odor and had a haze level of 48.
%, which was a rather low value.

Example 2 Isotactic polypropylene pellets (melt index 2.5 g/10 min measured under condition L of ASTM D 1238-73) and pellets of the composition used in Example 1 were coextruded at 260°C. A two-layer laminated sheet with a thickness of about 1 m/m was prepared (900 μm of polypropylene layer and 100 μm of the composition layer of the present invention). After preheating this sheet to 135℃,
While heating with an infrared heater, the film was stretched 5.0 times in the longitudinal direction using the difference in circumferential speed between the rolls, and then cooled to room temperature. Next, this is sent to a stenter, heated to 155°C, and stretched 10 times in the width direction.
After heat treatment at 156°C for 5 seconds, it was cooled and rolled up. The obtained film with a thickness of about 20 μm has a haze degree of 56
It was a beautiful translucent film.

Example 3 Instead of MgO as component D used in Example 1
A two-layer laminated biaxially stretched film was obtained in the same manner as in Example 1 except that CaCO ₃ was used. The haze of the film thus obtained was 55%, and the film had excellent translucency.

Comparative Example 1 A two-layer laminated biaxially stretched film was obtained in the same manner as in Example 1, except that the cyclohexanone peroxide of component C used in Example 1 was not added.

The haze of the film thus obtained was 11%, and a satisfactory translucent film could not be obtained.

Claims (1)

[Scope of Claims] 1 A: At least one of crystalline polypropylene, crystalline propylene-ethylene block copolymer, or crystalline propylene-α-olefin (excluding propylene) copolymer, B: Polyethylene if necessary Or with ethylene
(a) At least one copolymer of α-olefin (excluding ethylene) and/or (b) a radically polymerizable polar unsaturated compound, C: The decomposition temperature to obtain a half-life of 10 hours is approximately 60℃
D: at least one basic inorganic compound of group a metal of the periodic table;
A polypropylene composition for producing a translucent polypropylene film, characterized in that the component D is 0.001 to 1.0 parts by weight based on 100 parts by weight of component A or (A+B). .