JPH08176234A - Polypropylene resin for non-oriented film - Google Patents

Abstract

PURPOSE: To obtain a polypropylene resin for a non-oriented film improved in longitudinal tearing strength, impact strength, transparency and surface gloss by degrading a specified PP resin in the presence of an organic peroxide. CONSTITUTION: 0.005-0.1 pt.wt. organic peroxide is added to 100 pts.wt. PP resin having a melt flow rate(MFR) of 0.5-5g/10min and an Mw/Mn ratio of 5-7 (Mw is the weightaverage molecular weight and Mn is the number-average molecular weight) and the obtained mixture is melt-kneaded at 180-260 deg.C to obtain the degraded product being a PP resin for a non-oriented film, having an MFR of 7-20g/10min and an Mw/Mn ratio of 5 or below.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polypropylene resin for molding unstretched films.

[0002]

2. Description of the Related Art Conventionally, polypropylene resins for unstretched polypropylene films (hereinafter sometimes abbreviated as CPP) have a melt flow rate (MFR) of 5 to 12 from the practical viewpoint.

[Outside 3] However, such polypropylene resin is
When used at a film-forming speed of about 0 to 150 m / min, the obtained CPP has sufficient mechanical properties such as longitudinal tear (MD) strength and impact strength, and optical properties such as transparency and surface gloss. However, there was a desire for improvement. Also, for the purpose of improving productivity, when the film forming speed is increased to 180 m / min or more, the orientation of the film in the machine direction (MD) becomes large, and the physical properties of MD and transverse direction (TD) are anisotropic. As a result, the resulting CPP has a problem in that the MD strength and the impact strength are lowered, and the CPP cannot be put to practical use.

[0003]

The present invention not only solves the above-mentioned problems in the conventional ordinary film forming speed, but also obtains a CPP obtained even in a high speed film forming speed of 180 m / min or more. However, it is an object of the present invention to provide a polypropylene resin having good physical properties.

[0004]

Means for Solving the Problems As a result of earnest studies, the present inventors have found that a specific MFR and a specific MFR obtained by degrading a polypropylene resin having a specific MFR and a molecular weight distribution with an organic peroxide. The present invention has been accomplished by finding that a polypropylene resin exhibiting a molecular weight distribution can achieve the object of the present invention.

That is, the present invention has a melt flow rate (MFR) of 0.5 to 5 g / 10 minutes.

[Outside 4] To the effect.

The polypropylene resin used in the present invention is a polymer containing propylene as a main component, and other than homopolypropylene, propylene and other oleins such as ethylene, 1-butene and 1-hexene up to about 5% by weight. Copolymers are also included.

This polypropylene resin is required to have a specific melt flow rate (MFR) and molecular weight distribution, and MFR (JIS K7210; load 2.16k).
g, measured at 230 ° C.) is 0.5 to 5 g / 10 min, preferably 1 to 4 g / 10 min, molecule

[Outside 5] Is industrially difficult, and even if the specified value is adjusted, the object of the present invention cannot be achieved, and neither is preferable.

The above polypropylene resin (hereinafter referred to as raw material PP
Say. Examples of the organic peroxide used for degrading) include di-t-butyl peroxide, t-butylcumylperoxide, dicumyl peroxide, α, α′-
Bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t
-Butylperoxy) -3-hexene and the like.

The method of degrading the raw material PP using these organic peroxides is required by the polypropylene resin for an unstretched film (hereinafter referred to as the product PP) which is the object of the present invention.

[Outside 6] Although it is not specified, the raw material PP is usually added to the raw material PP1.
0.005 to 0.1 parts by weight of the organic peroxide is added per 100 parts by weight.
In addition to 0 parts by weight, it is usually carried out in an extruder or the like by melt-kneading at a temperature for melting the resin, for example, 180 to 260 ° C.

[0010] Degradation is made especially by using the MFR of the product PP as the raw material P.
It is desirable to be 2 to 30 times the MFR of P. Further, if necessary, additives such as an antioxidant, a neutralizing agent, an antiblocking agent and a slipperiness imparting agent may be added to the raw material PP before the degradation. Further, the organic peroxide may be diluted with an appropriate medium in order to improve the dispersibility in the raw material PP.

[0011]

[Outside 7] When the film is formed on P, the extrudability is poor and good molding cannot be performed.
If it exceeds 20 g / 10 minutes, drawdown will occur and not only the film-forming property will become a problem, but also the tear strength and the impact strength

[Outside 8] CPP having mechanical properties and optical properties cannot be obtained, and neither is preferable.

Polypropylene resin of the present invention (product PP)
The method of forming a non-stretched film by using is not specified, and a method generally used in industry is performed.

[0013]

EXAMPLES The present invention will now be described in more detail by way of examples. The percentages (%) in the examples are by weight except for the case of haze and gloss.

The physical properties of the raw material PP, the product PP and the unstretched film were measured according to the following methods.

[0015]

[Outside 9] Measured using GPC (gel permeation chromatography).

Haze ASTM D1003 Gloss JIS K7105 Tear strength ASTM D1922 MD strength is a value obtained by stacking 16 films, and TD strength is 1.
The value for a sheet of film. Punching impact strength A film impact tester manufactured by Toyo Seiki Co., Ltd. is used.

Measured at 23 ° C. using a hemispherical impact head with a diameter of 15 mm.

(Examples 1 to 3) 100 parts by weight of a raw material PP having the composition and physical properties shown in Table 1 (hereinafter referred to as "parts by weight") was added with 2,5
-A mixture of 20% dimethyl-2,5-di (t-butylperoxy) hexane and 80% liquid paraffin shown in Table 1, 0.1 part of antioxidant, 0.05 part of neutralizing agent,
0.1 part of an antiblocking agent and 0.1 part of a slipperiness | lubricity imparting agent were added, respectively, and it fully mixed with a Henschel mixer.

This product was supplied to a 50 mmφ single-screw extruder and extruded at 240 ° C. to obtain pellets made of product PP. Using the obtained pellets, a tandem extruder (1
A film having a thickness of 25 μm is obtained by extruding at 240 ° C. with an unstretched film extruder having 50 mmφ, 90 mmφ), rapidly cooling with a cooling roll at 30 ° C., and winding at a film forming speed of 120 m / min or 180 m / min. Was formed into a film.

The physical properties of the obtained film were measured and are shown in Table 2.

(Comparative Examples 1 to 3) The raw material PP having the composition and physical properties shown in Table 1 is used without being degraded or used in Example 3.

[Outside 10] A non-stretched film was formed in the same manner as in Examples 1 to 3 except that PP was used. The physical properties of these films were measured and are shown in Table 2.

[0022]

[Table 1]

[Table 2]

[0023]

The unstretched film obtained by using the polypropylene resin of the present invention has a film-forming speed (12
(0-150 m / min) not only the longitudinal tear (MD) strength, impact strength, transparency and surface gloss, which are problems in film physical properties, are greatly improved, but also high speed of 180 m / min or more. The mechanical strength can be improved even in film formation at
By showing good physical properties and enabling high-speed good film formation, which was not possible in the past, a great improvement in productivity can be achieved.

Claims (2)

[Claims] 1. A melt flow rate (MFR) of 0.5.
~ 5g / 10 minutes, heavy [External 1] [Claim 2] Polypropylene resin for stretched film.