JPS61152754A - Modification of polypropylene - Google Patents

Abstract

PURPOSE:Small amounts of an organic peroxide and a crosslinking agent area added to polypropylene so that they keep a prescribed ratio, then they are heat-treated at a specific temperature to improve melt tension and toughness without any adversely effecting shock resistance. CONSTITUTION:(A) 100pts.wt. of a polypropylene with a melt index of 0.5-30, preferably 2-20g/10min are combined with (B) 0.01-0.2, preferably 0.02-0.1pt.wt. of an organic peroxide, preferably whose decomposition temperature is 150-270 deg.C, when its half life is set to 1min, such as 1,3-bis(t- butylperoxisopropyl)benzene and (C) 0.05-1.5, preferably 0.06-1.2pt.wt. of a crossing agent, preferably a divinyl compound, maleimide or quinone dioxime so that the weight ratio of C/B becomes 3-12, preferably 4-10 and the resultant composition is heat-treated at 180-270 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for modifying polypropylene, and more particularly, the present invention relates to a method for modifying polypropylene, and more specifically, it improves polypropylene by dramatically improving melt tension and increasing rigidity without reducing impact strength. The present invention relates to a method for modifying polypropylene to improved polypropylene.

[Technical background of Masumei and its problems]

Among polyolefins, polypropylene is superior to other polymers in terms of transparency, rigidity, surface gloss, and heat resistance.

However, since such polypropylene has a low melt tension, its moldability decreases when it is applied to a blow molding method.

A known method for improving the melt tension of polypropylene is to blend polypropylene with low-density polyethylene obtained by a high-pressure method, but when these methods are applied, trying to improve the melt tension results in problems with transparency, A problem arises in that other physical properties such as rigidity deteriorate. Therefore, in order to deal with such problems, it is known to add inorganic fillers such as aluminum, mica, Merck, etc. for the purpose of improving rigidity, but this method reduces the impact strength after molding. However, a problem arises in that the specific gravity increases. Furthermore, it is known that a large amount of organic peroxide and cross-linking aid are blended to form a three-dimensional structure to improve heat resistance; However, a well-balanced modification method has not yet been developed.

[Purpose of the invention]

The present invention aims to solve the above-mentioned problems and provide a method for modifying polypropylene into polypropylene that has dramatically improved melt tension and improved rigidity without reducing impact strength.

[Summary of the invention]

As a result of intensive research to achieve the above-mentioned objective, the present inventors have found that polypropylene, which will be described later, is blended with a very small amount of an organic peroxide and a crosslinking aid, which will be described later, in a predetermined mixing ratio. The present invention was completed by discovering the fact that by heat-treating the polypropylene at the temperature described below, the polypropylene can be modified into a material with dramatically improved melt tension and improved rigidity without a decrease in impact strength. I came to the conclusion.

That is, in the method for modifying polypropylene of the present invention, 0.01 to 0.01 to 0.01 to 100 parts by weight of polypropylene having a melt index of 0.5 to 30 t and 710 minutes of polypropylene is added.
0.2 parts by weight and 0.05 to 1.5 parts by weight of the crosslinking aid (B) in the blending ratio of the organic peroxide (A) and the crosslinking aid (B). It is characterized in that it is blended in a weight ratio of 3 to 12 and heat treated at 180 to 270°C.

First, the polypropylene in the present invention has a melt index of 0.5 to 30 f/10 minutes, preferably 2.0 to 30 f/10 minutes.
20 f/10 min polypropylene. The type of polypropylene is not particularly limited, and examples include homopolymers and propylene-ethylene copolymers with an ethylene content of up to 20%.

The melt index is outside the above range and is 0.5f/
If it is less than 10 minutes, the fluidity of the polypropylene during modification will decrease, and if it exceeds 302/10 minutes, crosslinking will not be sufficiently performed and the improvement in melt tension will be insufficient.

Next, as for organic peroxides, those having a decomposition temperature in the range of 150 to 270° C. to give a half-life of 1 minute are preferable, and specifically, benzoyl peroxide and dichlorobenzoyl peroxide.

dicumyl peroxide, di-t-butyl peroxide,
2.5-Dimethyl-2,5-di(peroxide benzoate)hexyne-3,1,3-bis(t-butylperoxyisopropyl)benzene, lauroyl peroxide, -butyl peracetate.

2.5-dimethyl-λ5-di(butylperoxy)
Hexyne-3,2,5-dimethyl-2,5-di(i-butylperoxy)hexane, t-butyl perbenzoate, t-butyl perphenylacetate.

t-butyl burnin butyrate, t-butyl parzen ea
-Octate, t-butyl pervivalate.

/ MiA/perpivalate, t-butyl perdiethyl acetate, and the like. Of these,
1.3-bis(t-butylperoxyisopropyl)benzene, dicumyl peroxide, di-t-butyl peroxide, λ5-dimethyl-2.5-di(-1-pudelperoxy)hexyne-3,2,5- Dimethyl-λ5-di(
Preferred examples include i-butylperoxy)hexane.

These organic peroxides (8) are added in an amount of 0.01 to 0.2 parts by weight, preferably 0.02 to 0.1 parts by weight, per 100 parts by weight of the polypropylene mentioned above, and at the same time are added to the crosslinking aid described below. ) is required to satisfy the blending ratio CB)/(A). If the amount is less than 0.01 parts by weight, the reactivity will be poor and excellent physical properties will not be obtained, and if it exceeds 0.2 parts by weight, the reactivity will be too high and the fluidity will be poor. .

(in the crosslinking aid), for example, sulfur; divinyl compounds such as divinylbenzene; diallyl compounds such as diallyl phthalate; p-ginone dioxime + PN
Oxime compounds such as P'-dibenzoylquinone dioxime; maleimide compounds such as phenylmaleimide; as well as triallyl cyanurate, triallylisocyanurate, ethylene glycol methacrylate, polyethylene glycol methacrylate, 1,3.5- ) lyacryloylhexahydro-5-) riazine, liquid 1
．． Examples include oligomers having double bonds in the main chain or side chains such as 2-polybutadiene, and polymers having double bonds in the main chain or side chains such as syndiotactic-1,2-polybutadiene. Among these, divinyl compounds, ? They are leimide compounds and quinone dioxime compounds.

These crosslinking aids (B) are the polypropylene 10 described above.
0.05 to 1.5 parts by weight, preferably 0 parts by weight
．． 06 to 1.2 parts by weight, and at the same time, it is necessary to satisfy the later-described blending ratio (]1/(6) with the organic peroxide (A) mentioned above.This blending amount is 0.05 parts by weight. If the amount is less than 1 part by weight, the decomposition reaction will take priority and the physical properties will deteriorate, and if it exceeds 1.5 parts by weight, no further improvement in the physical properties will be observed, so it is meaningless.

The blending ratio of the organic peroxide (6) and the crosslinking aid (B) is (
6)/(A) is set at a weight ratio of 3 to 12, preferably 4 to 10. If this value is less than 3, the decomposition reaction takes precedence and the physical properties deteriorate; if it exceeds 12, no further improvement in the physical properties is observed, which is meaningless.

The modification of polypropylene of the present invention is carried out, for example, as follows. First, a predetermined amount of the above-mentioned polypropylene, organic peroxide, and crosslinking aid are mixed, for example, tri-blended, and then heat-treated at the temperature described below using a single-screw extruder or twin-screw kneader, and the mixture is melt-kneaded. and get a beret.

The temperature of heat treatment is 180-270℃, preferably 190-2
The temperature is 50°C. If the heat treatment temperature is less than 180°C, the organic peroxide will not be completely decomposed, and if it exceeds 270°C, the decomposition reaction will take priority and the physical properties will deteriorate.

[Embodiments of the invention]

Examples 1-8. Comparative Examples 1 to 4 Polypropylenes 1 to 5 shown in Table IK as polypropylenes
prepared. The melt index (MI) and various physical properties (flexural strength 1 flexural modulus, melt tension, Izod impact strength) of these polypropylenes were measured according to the following specifications and are also listed in Table 1.

Melt index: Compliant with JISK7210.

Bending strength: Based on JIS K7203.

Flexural modulus: Based on JIS K7203.

Using a melt tension tester manufactured by Toyo Seiki Co., Ltd., molten resin heated to 230°C was extruded from an orifice with a diameter of 2.09 m and a length of 8 mm at a speed of 20 m/min, and the extrudate was subjected to tension detection. This is the value of the tension when the extrudate is transferred to a commercial pulley and rotated at 20 r, p9 m, and the pulley winds up the extrudate.

Izotsu impact strength: Compliant with JIS K7110.

A notch was provided in the test piece.

Table 1 Organic peroxide (8) %a:L3'-bis(-
7' (peroxyisopropyl)benzene and (b) dicumyl peroxide were prepared.

As the crosslinking aid (6), a-nidivinylbenzene and b=
Paraquinone dioxime was prepared.

100 parts by weight of each of the polypropylenes described above was triblended with the organic peroxide (A) and crosslinking aid (B) in the amounts shown in Table 2, and then subjected to a tri-blend using a single-screw extruder. The mixture was melted and mixed at a good heat treatment temperature as shown in step 2, and then pelletized.

After measuring the melt index (MI) of the pellet, various test specimens were prepared using an injection molding machine, and the bending strength (2) flexural modulus and melt tensile (9) isot impact strength were measured according to the specifications described above. The ratio with the value of polypropylene before modification was calculated, and the measured value ratio is listed in Table 2.

〔Effect of the invention〕

As is clear from the above description, according to the method of the present invention, polypropylene can be modified into polypropylene that has dramatically improved melt tension and improved rigidity without reducing impact strength.

Therefore, even if the melt index is large, blow molding is possible, and it is effective when applied to the production of hollow molded products such as automobile materials 1 and materials related to low electric current.

Claims (1)

[Claims] Organic peroxide (A) 0.0.
01 to 0.2 parts by weight and crosslinking aid (B) 0.05 to 1.
5 parts by weight of the organic peroxide (A) and the crosslinking aid (B)
A method for modifying polypropylene, which comprises blending the polypropylene so that the blending ratio (B)/(A) is 3 to 12 by weight, and heat-treating at 180 to 270°C.