JPS61136546A - Modification of propylene/ethylene block copolymer - Google Patents

Abstract

PURPOSE:To obtain the titled modified copolymer which is excellent in rigidity, impact resistance, flow and moldability and can give a thin-walled molding, by mixing a specified propylene/ethylene block copolymer with an inorganic filler and an organic peroxide and heat-treating the mixture. CONSTITUTION:100pts.wt. propylene/ethylene block copolymer of a MI of 1-20g/10min and a C2H4 content of 4-20wt% is mixed with 0.5-9pts.wt. inorganic filler such as talc of an average particle diameter of 0.1-3.0mum, 0.01-0.2pt.wt. organic peroxide such as 1,3-bis(t-butylperoxyisopropyl)-benzene and, optionally, additives such as an antioxidant, antistatic agent, colorant, weathering agent and UV absorber, and the mixture is heat-treated at 190-260 deg.C to modify the titled copolymer.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a method for modifying a propylene-ethylene block copolymer, and more specifically, the present invention relates to a method for modifying a propylene-ethylene block copolymer. is excellent,
Moreover, the present invention relates to a method for modifying a propylene-ethylene block copolymer with excellent fluidity during processing.

[Technical background of the invention and its problems] Propylene-ethylene block copolymers have excellent rigidity and impact resistance, and are widely used as industrial materials in various fields.

Various attempts have also been made to further improve the physical properties of this copolymer. For example, JP-A-55-120E
i43, JP-A-56-88447, JP-A-57-7
No. 3033, JP-A-58-145748, etc. disclose that the copolymer is blended with inorganic fillers such as talc, calcium carbonate, and glass to further improve its rigidity and impact resistance. ing. However, the methods disclosed in these publications result in poor flow characteristics during production, leading to a decrease in moldability.

On the other hand, as a method of improving fluidity (processing characteristics), a method of adding organic peroxide was proposed in Japanese Patent Publication No. 51-30102.
No., JP 58-7885, JP 57-47305
No. 58-78444, etc. Although these methods do improve fluidity, they have the disadvantage that rigidity and impact resistance do not improve.

[Object of the invention] The present invention solves the above-mentioned problems, and provides a propylene-ethylene block copolymer that has high rigidity and impact resistance, and also has good fluidity during processing. The purpose is to provide a method for modifying.

[Summary of the Invention] As a result of intensive research to achieve the above-mentioned object, the inventors of the present invention have mixed the propylene-ethylene block copolymer described below with an inorganic filler and an organic peroxide in the amounts described below. When the propylene-ethylene block copolymer was heat-treated at the temperature described below, it was discovered that the resulting propylene-ethylene block copolymer had excellent rigidity and impact resistance, good appearance, and good fluidity during processing. It has been completed.

That is, the method for modifying a propylene-ethylene block copolymer of the present invention includes adding an inorganic filler to 100 parts by weight of a propylene-ethylene block copolymer having an MI of 1 to 20 g/10 minutes and an ethylene content of 4 to 20% by weight. 0.5 to 9 parts by weight and 0.01 to 0.2 parts by weight of organic peroxide are mixed,
It is characterized by performing heat treatment at 190 to 280°C.

First, the substances to be mixed in the present invention and their blending amounts are as follows.

Propylene-ethylene block copolymer.

1 to 20 g/10 minutes, preferably 2 to 10 g/1
0 minutes, the ethylene content is from 4 to 20% by weight, preferably 8
~15% by weight copolymer. MI of copolymer is Ig
If it is less than /10 minutes, no improvement in the elastic modulus can be expected even if the modification treatment of the present invention is performed, and if it exceeds 20 g/lo minutes, the impact strength will be insufficient. In addition, if the ethylene content is 4% by weight without grooves, the impact strength will be insufficient and 20% by weight.
If it exceeds % by weight, it will no longer exist as a block copolymer.

The method for producing the propylene-ethylene block copolymer to which the present invention is applied is not particularly limited, but can be produced, for example, as follows.

JP-A-58-122!309, JP-A-59-1208
As disclosed in Japanese Patent Application No. 11, etc., it is produced by multistage polymerization of two or three stages or more using a Ziegler-Natsuta catalyst. In this case, a propylene homopolymer is polymerized in the first stage, and a propylene-ethylene block copolymer is obtained by copolymerizing in the presence of ethylene or ethylene and propylene in the second and subsequent stages.

Next, as the inorganic filler, for example, the following can be used. Namely, talc, silica, mica, calcium carbonate, glass peas, barium sulfate,
Magnesium hydroxide.

Wallas night, calcium silicate fiber, carbon f#Ii fiber, magnesium oxysulfate fiber.

These include potassium titanate fiber, magnesium hydroxide, titanium oxide, calcium sulfite, white carbon, clay, glass fiber, and calcium sulfate.

Each of these may be used alone, or two or more types may be used in an appropriate combination.

Among these, it is preferable to use talc. In particular, the average particle size is 0.1 to 3.0 p-ta, preferably 0.
．． Talc of 5 to 2.5 l is useful because it contributes to improving impact strength and rigidity. Note that the average particle diameter of talc is 0.1
If it is less than JLm, impact strength and rigidity will decrease, and 3.0
If it exceeds pm, impact strength and rigidity will decrease.

The blending amount of the above-mentioned inorganic filler is 0.5 to 9 parts by weight, preferably 1 to 8 parts by weight, based on 100 parts by weight of the propylene-ethylene block copolymer.

When the amount is less than 0.5 parts by weight, the impact strength is rather reduced, and when it exceeds 9 parts by weight, the appearance becomes poor.

As the organic peroxide, for example, the following can be used. That is, 1.3 bis-(t-butylperoxyisopropyl)benzene, dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxybenzoate, 2.5 dimethyl-2,5-
Di(t-butylperoxy)-hexane, diinpropylbenzene hydroperoxide, E-butylcumyl peroxide, n-butyl 4,4'-bis(t-butylperoxy)murelate. 2.2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane.

These include di-t-butyl peroxyisophthalate, t-butyl peroxy acetate, methyl ethyl ketone peroxide, and the like.

Each of these may be used alone, or two or more types may be used in an appropriate combination.

The amount of the organic peroxide mentioned above is preferably 0.01 to 0.2 parts by weight per 100 parts by weight of the copolymer.
~0.1 part by weight. If the blending amount is less than 0 or oi parts by weight, high fluidity cannot be obtained, resulting in poor moldability, and if it exceeds 0.2 parts by weight, the molecular weight becomes excessively small, resulting in a significant drop in impact strength. descend.

In addition to the above-mentioned propylene-ethylene block copolymer, inorganic filler, and organic peroxide, additives such as antioxidants, antistatic agents, coloring agents, protective agents, and ultraviolet absorbers may be added as necessary. May be added.

The relationship between the order of mixing the above-mentioned substances and the heat treatment is determined by one of the following methods.

That is, during heat treatment, organic
How to mix j4 # compounds.

(B) A method in which a 7' propylene-ethylene block copolymer, an inorganic filler, and an organic peroxide are mixed, preferably triblended, and then heat treated.

Methods other than those described above, for example, a method in which an organic peroxide is added to a propylene-ethylene block copolymer in advance and modified by heat treatment as described below, and then an inorganic filler is mixed, improves the rigidity and impact strength of the copolymer. does not improve.

The following mixing and heat treatment are carried out using ordinary equipment 1.For example, mixing is carried out using a V-blender, Sfuper floater, etc.; heat treatment is carried out using a twin-screw kneader,
This may be carried out using a single screw extruder or the like.

The temperature during the above heat treatment is set in the range of 130 to 280"C, preferably 210 to 240"C.
If the temperature is less than 190°C, high fluidity during processing cannot be obtained, and if it exceeds 280°C, decomposition progresses too much and the impact strength decreases.

In the present invention, the copolymer that has been modified by the method of the present invention may be further modified by applying the method of the present invention again.

[Examples of the invention] Examples 1 to 9 Formerly, 100 parts by weight of a propylene-ethylene block copolymer with an ethylene content of the indicated value was added with an average particle size of 1 or 2.
Ratio of p, ra talc and 1.3 bis-(t-butylperoxyisopropyl)benzene (parts by weight)
After blending and mixing in a super floater for 10 minutes, heat treatment was performed at 230" O using a twin-screw mixer to mix the pellets. After measuring the MI of the obtained pellets, they were mixed in an injection molding machine. A test piece of a predetermined standard was prepared, and its flexural modulus, falling weight impact strength, and appearance were measured and evaluated.These evaluations were performed based on the following usage.

MI: Compliant with JIS K 721G.

Flexural modulus: Based on JIS K 7203.

Falling weight impact strength: Compliant with JIS K 7211.

Striking core diameter in inches, cradle inner diameter It was set to 5hm. Test piece size The length is 120mm, and the thickness is -120mm.

Appearance: The surface color tone of the 85 mm x 85 mm square plate was visually observed and evaluated as follows.

0...Good color tone.

×・・・・・・The surface appears darkened.

Comparative Examples 1 to 9 In Comparative Examples 1 to 6, talc and 1.3 bis-( t-butylperoxyisopropyl)benzene was added.

Comparative Example 7 is an example in which only talc was added to the copolymer,
Comparative Examples 8 and 9 are examples in which only an organic peroxide was added to the copolymer.

Comparative Example 10.11 The copolymer of Example 2.5 was heat-treated with an organic peroxide at 230°C, then talc was added thereto, and the mixture was kneaded and extruded into pellets at 230°C with a twin-screw kneader. After measuring the MI of the obtained pellet, a test piece of a predetermined standard was prepared using an injection molding machine, and its flexural modulus, falling weight impact strength, and appearance were measured and evaluated. That is, Example 2 corresponds to Comparative Example 11, and Example 5 corresponds to Comparative Example 10, and these are almost the same except for the different mixing order. [Effect of the Invention] From the Examples of the Invention As is clear, if a propylene-ethylene block copolymer is modified by the method of the great invention, the copolymer will have improved rigidity and impact resistance, as well as good fluidity during processing, and will also improve its appearance. Becomes good. therefore.

According to the present invention, it is possible to reduce the thickness of molded products made of the copolymer, improve productivity (l\cycle), and make it useful for manufacturing industrial materials in various fields such as home appliances and automobiles. be.

R6Q-

Claims (1)

[Claims] 1. MI 1-20 g/10 min, ethylene content 4-20
wt% propylene-ethylene block copolymer 100
A propylene-ethylene block combination characterized by mixing 0.5 to 9 parts by weight of an inorganic filler and 0.01 to 0.2 parts by weight of an organic peroxide, and heat-treating the mixture at 190 to 260°C. Method for modifying polymers. 2. The propylene according to claim 1, wherein the inorganic filler is talc with an average particle size of 0.1 to 3.0 μm.
Method for modifying ethylene block copolymer.