JPS6185462A - Production of polypropylene resin composition - Google Patents

Abstract

PURPOSE:To provide the titled composition having high rigidity as well as high impact strength, and suitable for automobile use, etc., by compounding specific amounts of an organic perixode and a crosslinking assistant to a composition composed of a propylene-ethylene block copolymer having low MI value and a specific ethylene-alpha-olefin random copolymer. CONSTITUTION:The objective composition can be produced by compounding 100pts.(wt.) of a resin composition consisting of (A) 60-80(wt)%, preferably 65-75% propylene-ethylene block copolymer having an MI value of 0.01-5;10min and an ethylene content of preferably 1.0-15% and (B) 15-40%, preferably 25-35% ethylene-alpha-olefin random copolymer having an ethylene content of 40-80%, with (C) 0.01-1pt. of an organic peroxide (e.g. benzoyl peroxide) and (D) 0.05-5pts. of a crosslinking agent (e.g. sulfur, divinylbenzene, etc.) (C/D=1/1-1/10), and melting and kneading the mixture.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for producing a polypropylene resin composition,
More specifically, the present invention relates to a method for producing a polypropylene resin composition that has both high rigidity and impact strength, especially low-temperature impact strength.

[Technical background of the invention and its problems]

Although polypropylene resin has high rigidity, it has the disadvantage of low impact strength, particularly low-temperature impact strength.

As an improvement method for this point, ■ ethylene propylene rubber,
A method of mechanically friending butadiene rubber, etc., and a method of copolymerizing it with ethylene, butadiene or other α-olefins have been proposed and implemented. Since these methods all involve the presence of a rubber component, the impact strength of the resulting resin composition is improved.

However, on the other hand, it has the disadvantage of causing a decrease in rigidity.

Therefore, there is a strong need for a method for producing a polypropylene resin composition that has excellent both rigidity and impact strength.

[Purpose of the invention]

The present invention aims to provide a new method for producing a polypropylene resin composition that maintains high rigidity and has high impact strength. [Summary of the Invention] The present inventors have conducted extensive research to achieve the above objectives. As a result of stacking, an organic peroxide and a crosslinking coagent are added to a resin composition of a predetermined ratio of a propylene-ethylene block copolymer having a low MI value and an ethylene-α olefin random copolymer having a predetermined ethylene content. When blended in a predetermined amount and melted and kneaded,
It was discovered that the obtained polypropylene resin composition has both of the above properties at a high level, and the method of the present invention was developed.

That is, the method for producing a polypropylene resin composition of the present invention has a melt index (MI) of 0.01 to 5 g/
10 minutes of propylene-ethylene block copolymer (A
) 60-85% by weight and ethylene content 4o-sow f
is ethylene-α olefin random copolymer (B)
0.01 to 1.0 parts by weight of organic peroxide (C) and 0.05 to 5.0 parts by weight of crosslinking aid (D) per 100 parts by weight of a resin composition consisting of 15 to 40 parts by weight. It is characterized by adding and mixing, and then melting and kneading.

First, in a resin composition consisting of a copolymer (A) and a copolymer (B), the amount of the former is 60 to 85% by weight, preferably 65 to 75% by weight, and therefore the amount of the latter is 15-40% by weight.

Preferably, the content is 25 to 35% by weight. If the amount of the former is less than 60% by weight (if the amount of the latter exceeds 40% by weight), the mechanical strength originally possessed by the polypropylene resin will be reduced in the final polypropylene resin composition. 9. Characteristics may not be fully demonstrated. Moreover, if the amount exceeds 85% by weight (the latter amount is less than 15N), the impact strength will not improve.

At this time, the copolymer (A) has an MI value of 0.01 to
Use one that weighs 5g and 710 minutes. Preferably 0.01
~3 g/l 0 min, more preferably 0.1-1.09
/10 minutes. If a material with an MI value of less than 0.019710 minutes is used, its fluidity will be poor and crosstalk during composition production will be difficult; conversely, if a material with an MI value of more than 5 g/10 minutes is used, The impact strength of the resulting resin composition is not sufficiently improved.

Moreover, in this copolymer (A), it is preferable that the ethylene content is 1.0 to 15% by weight.

Copolymer (A) fi can be produced by a two-stage or three-stage multistage polymerization method using a Ziegler-Natsuta catalyst. For example, in the first stage, a propylene homopolymer is polymerized, and in the second and subsequent stages, the polymerization reaction is carried out in the presence of ethylene or in the coexistence of ethylene and propylene. The pressure in each stage of the polymerization reaction is from several atmospheres to 40 atmospheres, and the temperature is from room temperature to 80C.
Also, the polymerization reaction is solution polymerization.

Slurry polymerization, gas phase polymerization, or a combination thereof can be applied.

The copolymer (B) used has an ethylene content of 40 to 80% by weight. If a polypropylene resin composition having an ethylene content of less than 40% by weight is used, the low-temperature impact strength of the obtained polypropylene resin composition will be extremely reduced and crystal growth will be too advanced, which is not preferable. Moreover, if more than 80% by weight is used, crystallinity becomes too high, which is not preferable.

The α-olefin in the copolymer (B) may be an α-olefin having 3 to 15 carbon atoms, and among these, propylene, 1-butene, 1-hexene, etc. are preferred.

Next, the organic peroxide (C) is preferably one whose decomposition temperature at which the half-life is 1 minute is in the range of 150 to 270C, and specifically, benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide,
Di-L-butyl peroxide, 2,5-dimethyl-2,
5-di(peroxide benzoate) hexyne-3゜1
．． 3-bis(1-butylperoxyisopropyl)benzene, lauroylperoxide, t-butylperacetate), 2,5-dimethyl-2,5-cy(t-phthylperoxy)hexyne-3,2,5- Dimethyl-2,5-di(t-butylperoxy)hexane, t-buterperpensoate, t-butylperphenylacetate, t
-butylbar isobutyre), t-fulbar 5e
Examples include c-octate, t-butyl perbivalate, cumyl verpivalate), and t-phthyl verdiethyl acetate. Among these, 1,3-bis(
t-butylperoxyisopropyl)benzene, dicumyl peroxide, di-t-butyl peroxide.

2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3,2,5-dimethyl-2,5-di(t-
) (ethylperoxy)hexane and the like are preferred.

These organic peroxides (C) are the above-mentioned copolymers (A)
αol to 1.0 parts by weight are added to 100 parts by weight of the resin composition consisting of copolymer CB) and copolymer CB). If this amount is less than 0.01 part by weight, the impact strength improvement effect will be insufficient, and if it is more than 1 part by CNjf, the polypropylene resin will undergo many molecular breaks and the overall mechanical strength will deteriorate. This results in a decrease in Preferably 0.05-0. This is the IM quantity department.

Examples of the crosslinking aid (D) include sulfur; divinyl compounds such as divinylbenzene; diallyl compounds such as diallyl phthalate; p-quinonedioxime, p, p
oxime compounds such as '-dibenzoylquinone dioxime; maleimide compounds such as phenylmaleimide;
Besides, triallyl cyanurate, triallyl isocyanurate, ethylene glycol methacrylate, polyethylene glycol methacrylate.

1.3.5-) Liacryloylhexahydro-3-triazine, oligomers having a double bond in the main chain or side chain such as liquid 1,2-polybutadiene, etc. Polymers having a double bond in the main chain or side chain can be mentioned. , α0
It is blended in an amount of 1 to 5.0 parts by weight. If the amount is less than 0.01 parts by weight, the effect as a crosslinking aid will not be sufficiently exhibited, and if it is more than 5.0 parts by weight, the impact strength will not be further improved. It is meaningless and meaningless.

The blending ratio of the organic peroxide (C) and the crosslinking aid (D) is preferably set to 1/1 to 1/10. If this value is larger than 1/1, the crosslinking phenomenon will not progress to a dominant degree, and if it is smaller than 1/10, the crosslinking aid will remain and the mechanical properties of the 7'C resin composition will deteriorate. This is because it may invite

The polypropylene resin composition according to the present invention can be produced, for example, as follows.

First, predetermined amounts of the copolymer (A) and copolymer (B), which have already been described in detail, are triblended and then melt-kneaded to form pellets of the resin composition. The mixer used for triblending may be a tumbler, a Ribbon Fender 1 Hensiel mixer, or the like.

However, Panbali mixer is not preferred. Melting crosstalk is
This may be carried out at a temperature of 180 to 260C using a conventional single-screw extruder or the like.

Next, a predetermined amount of the above-mentioned organic peroxide (C) and a crosslinking aid (D''>17) are blended into a predetermined amount of the pellet of this resin composition, and the whole is melt-kneaded using, for example, a single-screw extruder. Pelletize.

The temperature applied during this melting and crossing is 190 to 240C.

Preferably it is 200-220C. If the temperature is less than 190G, the impact strength of the resulting resin composition will not improve, and if it is higher than 240G, decomposition occurs preferentially over crosslinking during melt mixing, which is not preferable. The time for performing the melt crossing is 0.5 to 2 minutes, preferably 1 to L5 minutes. If the time is shorter than 0.5 minutes, the decomposition of the blended organic peroxide (C) will not be completed, and if it is longer than 5 minutes, crosslinking will proceed excessively and the mechanical properties of the resulting resin composition will deteriorate. impact strength is not improved.

[Embodiments of the invention]

Examples 1-7. Comparative Examples 1 to 4 The following three types of propylene-ethylene block copolymers (A) were prepared.

(a): Idemitsu Voliv e+ E-150G (MI
(b): Idemitsu Polypro E-250G (MI 0.67
9/10 minutes, ethylene content 4.0% by weight; same as above) (C)
: Idemitsu Polypro J-750H2 (MI 9.19/1
0 minutes, ethylene content 5.1% by weight; same as above) As the ethylene-propylene random copolymer (B), ethylene content 73% by weight, Mooney viscosity ML! +4 (100C)
70 ethylene propylene rubber, organic peroxide (C
1,3-bis(t,-)benzene was prepared as the tilting agent, and divinylbenzene was prepared as the tilting agent.

First, copolymer (A) and copolymer CB) were triblended in the indicated combinations and proportions and mixed thoroughly, and then fed into a single-screw extruder at a set temperature of 230C to form pellets.

Organic peroxide (
C) and the crosslinking aid (D) were blended in the indicated proportions (parts by weight) and mixed again.

Next, this mixture was supplied to a single-screw extruder with a set temperature of 210C and melt-kneaded for 1 minute to form pellets. Finally, test pieces were prepared by injection molding this pellet, and various properties of each of these test pieces were measured according to the following specifications. The results are summarized in the table.

Bending strength: Compliant with JIS K7203 Flexural modulus: Compliant with JIS K7203 Izot impact strength: Compliant with JIS K7110 [Effects of the Invention] As is clear from the above explanation, the method of the present invention provides high rigidity and impact strength, especially low-temperature impact strength. It is possible to produce a polypropylene resin composition that has both of the following characteristics. A polypropylene resin composition having such characteristics is useful because it can be applied to various industrial material fields such as automobile materials 1 and materials related to low electric current.

Claims (1)

[Claims] 1. Melt index (MI) is 0.01 to 5 g/1
0 minute propylene-ethylene block copolymer 60-8
5% by weight and 15-40% by weight of an ethylene-α olefin random copolymer with an ethylene content of 40-80% by weight, 0% by weight of organic peroxide.
．． 1. A method for producing a polypropylene resin composition, which comprises adding and mixing 0.01 to 1.0 parts by weight and 0.01 to 5.0 parts by weight of a crosslinking aid, followed by melt-kneading. 2. The method for producing a polypropylene resin composition according to claim 1, wherein the propylene-ethylene block copolymer has an MI of 0.1 to 1.0 g/10 min.