JPH0653386B2 - Translucent polypropylene film - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a translucent polypropylene film.

[0002]

2. Description of the Related Art At present, semi-transparent films containing a polypropylene resin as a main component and having a rough surface are being actively developed as medical, industrial and food packaging films.

As a method for producing a translucent polypropylene film having such a rough surface, a polyolefin other than polypropylene, for example, polyethylene is added to polypropylene, a foaming agent is added to polypropylene, or a special quinacridone derivative or the like is used. A method has been proposed in which a nucleating agent is added to polypropylene, the mixture is melt-molded to form a polypropylene sheet having a β-type crystal structure, and the polypropylene sheet is stretched.

[0004]

In these methods, the optimum condition range for obtaining a desired rough surface is narrow, special molding conditions are required, the degree of roughening is low, or There are problems such as improper balance with other physical properties, and considerable improvement is required.

As a result of intensive investigations by the present inventors on a translucent polypropylene film, a specific propylene-
By combining the ethylene block copolymer with a specific organic peroxide, a film having a significantly increased haze, which is a measure of translucency, can be obtained, and the melt flow index can be easily controlled, and The inventors have found that the haze is unlikely to change depending on the molding conditions and have reached the present invention.

[0006]

That is, the present invention provides (A)
0.5 to 60% by weight of a block polymerization part having an ethylene content of 50 to 100% by weight, and a propylene homopolymerization part having a propylene content of 80% by weight or more, or a copolymerization part of propylene and another α-olefin. 100 parts by weight of a crystalline propylene-ethylene block copolymer consisting of 99.5 to 40% by weight, and (B) 0.001 to 1 part by weight of an organic peroxide having a decomposition temperature of 60 ° C. or more with a half-life of 10 hours. Parts, and (C) 0.5 to 100 parts by weight of a copolymer of polyethylene or ethylene having an ethylene content of 50% or more and another α-olefin and / or a radically polymerizable polar unsaturated compound. An unstretched film, a uniaxially stretched film, or a biaxially stretched film produced by using the product, and a product including the film as at least one layer and further another film layer. It relates to an unstretched film of layers, a uniaxially stretched film or a biaxially stretched film.

The crystalline propylene-ethylene block copolymer which is the component (A) used in the present invention has a block-polymerized portion having an ethylene content of 50 to 100% by weight. The polymerized portion other than the block polymerized portion is composed of a propylene homopolymerized portion having a propylene content of 80% by weight or more or a copolymerized portion of propylene and another α-olefin. Examples of the α-olefin include one or two or more selected from ethylene, butene-1, isobutene, hexene-1, 4-methylpentene-1, styrene and the like.

The proportion of the block polymerized portion in the component (A) is 0.5 to 60% by weight, preferably 2 to 40% by weight, and particularly preferably 3 to 30% by weight. 0.5
When the amount is less than wt%, the haze is small and the effect of increasing the haze due to the organic peroxide is less likely to appear. 60% by weight
If it exceeds, the haze becomes almost the upper limit, and the manufacturing cost of the block copolymer itself is considerably high, so that there is little merit.

When the ethylene content in the block polymerized portion of the component (A) is less than 50% by weight, the haze is small, and the production of this block copolymer becomes very difficult. It is difficult to do and has little merit.

As the organic peroxide which is the component (B) used in the present invention, one having a decomposition temperature at which the half-life is 10 hours is 60 ° C. or higher, preferably 60 to 150 ° C. is suitable. Examples of such organic peroxides include lauroyl peroxide (62 ° C.), benzoyl peroxide (72 ° C.), cyclohexanone peroxide (97 ° C.), t-butyl peroxyisopropyl carbonate (98 ° C.), t-butyl peroxide. Oxybenzoate (105 ° C), methyl ethyl ketone peroxide (1
05 ° C), dicumyl peroxide (117 ° C), 2,5
-Dimethyl-2,5-di (t-butylperoxy) hexane (118 ° C), di-t-butylperoxide (126
C.), 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane-3 (160.degree. C.) and the like.

The amount of the component (B) used is 100 parts of the component (A).
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. If the amount is less than 0.001 part by weight, the effect of adding the organic peroxide cannot be seen. 1
Although the addition effect is seen when the amount is more than parts by weight, the melt flow index of the obtained polypropylene resin composition becomes too high,
Not suitable for film production.

In order to further improve the haze of a film made from the composition containing the component (A) and the component (B), or to improve the film forming suitability, the following component (C) is added. Often effective. Component (C): Polyethylene having an ethylene content of 50% or more, or a copolymer of ethylene and another α-olefin and / or a radical-polymerizable polar unsaturated compound.

The component (C) will be specifically described. 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, and copolymers with one or more selected from them.

The preferable addition ratio of the component (C) is
0.5 to 100 parts by weight per 100 parts by weight of component (A),
Preferably 1 to 50 parts by weight, more preferably 2 to
30 parts by weight.

When producing the translucent polypropylene film of the present invention, various known additives are added as necessary to the composition containing the components (A), (B) and (C). Things are free. Known additives include
Examples include various stabilizers, antistatic agents, organic lubricants, antiblocking agents, and coloring agents.

When the translucent polypropylene film of the present invention is produced, the raw materials may be mixed in advance and pelletized for molding, or they may be simply put in a molding machine. The mixture of the above raw materials may be directly supplied.

The semitransparent polypropylene film of the present invention is an unstretched film produced using only the above composition,
It may be a uniaxially or biaxially stretched film, or an unstretched film produced by using only the above composition, a uniaxially or biaxially stretched film to another unstretched polyolefin film or a uniaxially or biaxially stretched polyolefin film. It may be a film obtained by laminating the above composition or a film obtained by laminating the above composition and another polyolefin by coextrusion. Incidentally, a film obtained by laminating an unstretched polyolefin film or a uniaxially stretched polyolefin film, or a film obtained by laminating the above composition and another polyolefin by coextrusion is further subjected to a stretching process to form a uniaxially or biaxially stretched film. You can also do it. Thus, the translucent polypropylene film of the present invention may be used in an unstretched state, or may be used in a uniaxially or biaxially stretched state, if necessary.
A more beautiful and uniformly roughened surface can be obtained by uniaxially or biaxially stretching.

The semi-transparent film of the present invention, particularly the stretched semi-transparent film, has a wide range of uses as follows: (1) By laminating the present film on a printed matter or photograph, Change the shiny appearance into a moist and calm appearance. (2) When this film is printed, the printed finish will have a moist and calm appearance. (3) By sticking this film and a metal foil such as aluminum, the glittering feeling of the metal foil can be eliminated. (4) By vapor-depositing a metal such as aluminum on this film, a vapor-deposited film with no glitter can be obtained. (5) Since this film has a good impregnation property for oils such as electric insulating oil, it is also excellent as an insulating layer for electric devices (such as capacitors and transformers) that require oil impregnation. (6) Since this film has excellent releasability, it can be used as a release film when molding an unsaturated polyester resin or a melamine resin. (7) Since this film can be heat-sealed, it can be directly made into a bag or placed in an automatic packing machine. Further, when heat is applied to the rough surface side, only that portion becomes transparent. Therefore, by utilizing this, a patterned film in which transparent portions and semi-transparent portions are mixed can be formed. This transparency can also be achieved by printing a colorless ink on the rough surface side. (8) If an adhesive is applied to one side of the present film to form an adhesive tape or an adhesive sheet, even if the adhesive tape is adhered to an article, the adhesive portion does not stand out. Also,
Even if you repair damaged parts such as documents with this tape and copy it, the tape hardly appears on the copy side,
You can make a clean copy.

As described above, the translucent polypropylene film of the present invention has a very wide range of uses and is very useful. The present invention will be described in more detail by the following examples, which are not intended to limit the present invention.

Example 1 A crystalline propylene-ethylene block copolymer (ASTM D-1238) comprising about 25% by weight of a block copolymerized portion having an ethylene content of 76% by weight and about 75% by weight of a propylene homopolymerized portion. 90 parts by weight of melt index 4.5 g / 10 min) measured under the condition L of -73.
0.08 parts by weight of dicumyl peroxide and 10 parts by weight of low-density polyethylene (melt index 5 g / 10 minutes measured by ASTM D-1238, condition E) were sufficiently mixed with a mixer and supplied to a pelletizer.
Melt processed at ° C to pellet. The melt index of this pellet (according to condition L of ASTM D-1238-73) was 7.8 g / 10 minutes. The pellets obtained are fed to an extruder and the thickness is about 160 μm at 240 ° C.
It was melt-extrusion laminated on a uniaxially stretched polypropylene film to obtain a bilayer sheet having a total thickness of 180 μm.

Then, the obtained sheet was T. M. Lon
The film was set on a film stretcher manufactured by Company g and heated to 150 ° C., and stretched 7 times in the direction perpendicular to the stretching direction of the uniaxially stretched polypropylene as a base material to obtain a clean semitransparent film having a thickness of about 25 μm. This film has a base polypropylene in a biaxially stretched state, and a layer thereover in a uniaxially stretched state. The haze of this film is 5
It showed a very high value of 6% (measurement of haze was determined by ASTM
D-1003-61 was used to measure one film).

Comparative Example 1 Pellets were prepared in the same manner as in Example 1 without using dicumyl peroxide. The melt index of the obtained pellets was 4.7 g / 10 minutes, and the haze of the film formed from the pellets in the same manner as in Example 1 was 28%, which was inferior to that in Example 1.

Example 2 The pellets used in Example 1 were fed to an extruder to produce 25
It was melt extruded at 0 ° C. to make a sheet having a thickness of about 1 mm. This sheet was preheated to 130 ° C. and then stretched 5 times in the longitudinal direction between two sets of nip rolls having different rotation speeds by utilizing the difference in peripheral speed of the rolls. This uniaxially stretched sheet was fed into a tenter, stretched 10 times in the width direction while being heated to 150 ° C., then heat-treated at 150 ° C. for 4 seconds, then cooled and wound. The resulting film having a thickness of about 20 μm had a paper-like feel and a haze of 75%.

Example 3 Pellets (a) used in Example 1 and polypropylene (Mitsui Noblen JH-G, melt index 3.8 g)
/ 10 min) and (b) were fed to a two-layer film extruder (extrusion temperature was set to 250 ° C.) in which two 20 mmφ extruders were combined, and the thickness ratio of (a) layer / (b) layer was 1/2
Then, a sheet having a total thickness of 700 μm was prepared. Then, the obtained sheet was T.I. M. The film was set on a film stretcher manufactured by Long Co., and heated at 150 ° C. and stretched 5 times in the MD direction and 7 times in the TD direction to obtain a biaxially stretched film having a thickness of about 20 μm. The haze of this film was extremely high at 67%.

[0025]

As described above, the translucent polypropylene film of the present invention is a film in which the degree of haze, which is a measure of translucency, is significantly increased, and the melt flow index can be easily controlled, and The haze hardly changes depending on molding conditions, has a very wide range of applications, and is very useful.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08L 53/00 LLY 7142-4J // B29K 23:00 C08L 23:16 (72) Inventor Ken Kawakami City 1-1-1, Sonoyama, Otsu City, Shiga Prefecture

Claims (2)

[Claims] 1. (A) 0.5 to 60% by weight of a block polymerization part having an ethylene content of 50 to 100% by weight, and a propylene homopolymerization part having a propylene content of 80% by weight or more or propylene and other 100 parts by weight of a crystalline propylene-ethylene block copolymer consisting of 99.5 to 40% by weight of a copolymerized portion with an α-olefin, (B) an organic solvent having a decomposition temperature of 60 ° C. or higher for a half-life of 10 hours. Oxide 0.001 to 1 part by weight, and (C) Polyethylene having an ethylene content of 50% or more, or a copolymer of ethylene and another α-olefin and / or a radical-polymerizable polar unsaturated compound 0.5 To 100 parts by weight, a non-stretched film, a uniaxially stretched film or a biaxially stretched film. 2. (A) 0.5 to 60% by weight of a block polymerization part having an ethylene content of 50 to 100% by weight, and a propylene homopolymerization part having a propylene content of 80% by weight or more, or propylene and other 100 parts by weight of a crystalline propylene-ethylene block copolymer composed of 99.5 to 40% by weight of a copolymerized portion with an α-olefin, and (B) an organic solvent having a decomposition temperature of 60 ° C. or higher with a half-life of 10 hours. Oxide 0.001 to 1 part by weight, and (C) Polyethylene having an ethylene content of 50% or more, or a copolymer of ethylene and another α-olefin and / or a radical-polymerizable polar unsaturated compound 0.5 To 100 parts by weight, a non-stretched film, a uniaxially stretched film, or a laminated unstretched film having at least one biaxially stretched film, Biaxially stretched film or biaxially oriented film.