JPH03250040A - Polyolefin resin composition and its injection molding - Google Patents

Abstract

PURPOSE:To obtain the title composition which can give injection moldings having a low coefficient of linear expansion and excellent impact resistance and mechanical strengths by mixing PP with an ethylene/propylene copolymer rubber and/or an ethylene/butene copolymer rubber and talc in a specified mixing ratio. CONSTITUTION:30-60wt.% PP (A) is mixed with 30-40wt.% ethylene/propylene copolymer rubber and/or ethylene/butene copolymer rubber (B) and 10-30wt.% talc in a B to A weight ratio of 0.5 or higher.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a polyolefin resin composition and an injection molded article thereof, and in particular, the injection molded article has a sufficiently low coefficient of linear expansion and has good moldability and dimensional stability. The present invention relates to a polyolefin resin composition having excellent impact resistance and mechanical strength, and injection molded products thereof.

[Conventional technology]

Polypropylene is lightweight and has excellent mechanical strength, so it is widely used in various fields. However, it has poor impact resistance, so in order to improve it,
Various polypropylene resins have been proposed, which are made by adding ethylene-propylene copolymer rubber (EPR), inorganic fillers, etc. to a propylene-ethylene block copolymer.

JP-A-61-12742 discloses (a) ethylene content of 2 to
3% by weight, melt flow rate 40-45g/10 min Nofrovirene-ethylene block copolymer 62-57% by weight, (b) ethylene content 70-80% by weight, Mooney viscosity, +4 (100°C) 55- 58 ethylene-propylene copolymer rubber 26-28% by weight, (c) density 0.
955-0.960 g/cut.

2-3% by weight of high-density polyethylene with a melt flow rate of 18-22g/10min, (d) average particle size of 1.8-2.
2, consisting of 10-12% by weight of talc with a specific surface area of 36,000-42,000 cd/g, and a melt flow rate of 1
3 le 18 density 0. 950-0. 980 g/ca
t, flexural modulus 11500-14000 kg/c
Ill, linear expansion coefficient between 20 and 80℃ 7×10″S~
10X 110-5a/am/ and JIS-28
741 60°-60.

The present invention discloses a resin composition characterized by a surface gloss of 55% or more by a method.

JP-A No. 63-57653 discloses that polypropylene is
1 part, 20 to 50 parts of ethylene propylene rubber, 0 to 20 parts of talc, and 2 parts of whiskers.

Discloses a resin composition characterized in that it contains 5 to 20 parts of an inorganic filler.

JP-A No. 63-95252 discloses that (a) the ethylene content is 3
~30% by weight, melt index at 230°C (
(b) Crystalline ethylene-propylene block copolymer having Ml) of 4 g/10 min or more 40-80% by weight, (b) Propylene-ethylene block copolymer content 10-90%
Weight %, Mooney viscosity ML. at 100°C. ．． ．． (100
5 to 10% by weight of ethylene-propylene copolymer rubber and/or ethylene-propylene-diene terpolymer rubber having a temperature of 15 to 110 °C), (c) a surface treatment agent in a dry or semi-dry pulverizer; Talc surface treated with 2
~25% by weight, (d) Barium sulfate with an average particle size of 1 or less 2-25% by weight, (e) Columnar or acicular carbonic acid with an average particle size of 5 or less and an aspect ratio of 2.5 or more Calcium 1-IO wt%, and (f) nucleating agent 0
．． 01 to 0.5% by weight (However, the above components (a) to (
Discloses a resin composition consisting of (based on the total amount of e)).

Furthermore, JP-A-1-118557 discloses a resin composition characterized in that 5 to 15% by weight of potassium titanate whiskers are mixed in a resin composition in which polypropylene resin and ethylene propylene rubber are mixed. There is.

Furthermore, JP-A No. 1-149845 discloses that (a) boiling xylene solubles having an ethylene content of 20 to 60% by weight are
(b) a propylene-ethylene block copolymer containing 12% by weight, an ethylene content of the entire polymer of 1 to 7% by weight, and a melt flow rate of 15 to 50 g/10 minutes; 20 to 60% by weight and Mooney viscosity MLl+4 (100°C) is 100 to 15
(e) 3 to 6% by weight of talc having a specific surface area of 30,000 cal/g or more and an average particle size of 0.5 to 2.0 mm. Discloses a resin composition characterized in that it is made by blending.

[Problem to be solved by the invention]

However, JP-A-61-12742, JP-A-63-
Since the resin compositions of No. 95252 and JP-A-1-149845 have linear expansion coefficients of 6 x 10-'cm/cm/ or more, dimensional errors are likely to occur during assembly, and they are not suitable for use in bumpers, for example. In some cases, there is a problem in that the bumper is easily deformed due to the difference in coefficient of linear expansion with the vehicle body when placed in a high-temperature environment, which may impair its appearance.

Furthermore, although the resin composition of JP-A-1-118557 has a low coefficient of linear expansion, it has a problem of poor impact resistance at low temperatures.

Furthermore, although the resin composition of JP-A No. 63-57653 has a low linear expansion coefficient of 7 x 10-5 cm/am/°C or less, the linear expansion coefficient in the longitudinal direction (MD force direction) of the injection molded product is I can't say it's still small enough.If...
If the coefficient of linear expansion in the longitudinal direction (MD force direction) can be further reduced, it is advantageous because the molding efficiency and assembly efficiency of various molded products can be improved.

Therefore, the purpose of the present invention is to improve the linear expansion coefficient of injection molded products.
Particularly, the object of the present invention is to provide a polyolefin resin composition having a sufficiently small coefficient of linear expansion in the longitudinal direction and good impact resistance and mechanical strength, and an injection molded product thereof.

[Means to solve the problem]

As a result of intensive research in view of the above problems, the present inventors have developed a composition comprising polypropylene, ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber, and an inorganic filler such as talc in predetermined amounts. In, ethylene-propylene copolymer rubber and/or ethylene-propylene copolymer rubber
It has been discovered that an injection molded product made of a resin composition in which the blending ratio of butene copolymer rubber and polypropylene is limited to a specific range has a sufficiently small coefficient of linear expansion, particularly in the longitudinal direction, and has developed the present invention. I came up with the idea.

That is, the first polyolefin resin composition of the present invention comprises (a) 30 to 60% by weight of polypropylene, and (b) 30 to 40% by weight of ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber. and (c) 10 to 30% by weight of talc, and the weight ratio of the (a) polypropylene to the (b) ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber (b) / (a) is larger than 0.5.

Further, the second polyolefin resin composition of the present invention comprises (a) 30 to 60% by weight of polypropylene, and (b) 30 to 40% by weight of ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber. , (c) containing 10 to 30% by weight of talc and whiskers, and the weight ratio (b) of the (a) polypropylene to the (b) ethylene propylene copolymer rubber and/or ethylene-butene copolymer rubber. / (a) is larger than 0.5, and (c) the weight ratio of talc and whiskers (whisker/talc) is 1/2 or less.

Furthermore, the injection molded article of the present invention made of the above composition is characterized in that the average coefficient of linear expansion in the longitudinal direction and the width direction at a temperature of 20 to 80°C is 5 x 10-5 cm/cm/t' or less. shall be.

The present invention will be explained in detail below.

In the present invention, (a) polypropylene is not limited to a homopolymer, but also a random or block copolymer with other complementary olefins containing a propylene component of 50 mol% or more, preferably 80 mol% or more can also be used. Comonomers copolymerized with propylene include ethylene and other α-olefins, with ethylene being particularly preferred. Therefore, the term "polypropylene" used herein is not limited to homopolymers of propylene, but should be understood to include copolymers as well.

When a propylene-ethylene block copolymer is used as the polypropylene, the ethylene content is preferably 4 to 20% by weight, particularly preferably 5 to 15% by weight. Also, the melt fluorate (MPR230t, 2.16kg
Load) is preferably in the range of 0.5 to 50 g/10 minutes, more preferably 9 to 30 g/10 minutes.

The content of polypropylene as mentioned above is 30-60% by weight, preferably 37-56% by weight. If the polypropylene content is less than 30% by weight, the mechanical strength will decrease;
If it exceeds % by weight, it becomes difficult to sufficiently reduce the coefficient of linear expansion of the injection molded product.

Note that the content of polypropylene itself is not a legal value by itself, but is set at a specific weight ratio with ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber, as described below. be done.

In the present invention, (b) ethylene-propylene copolymer (BPR) rubber has a content of repeating units derived from ethylene of 10 to 90 mol% and a content of repeating units derived from propylene of 90 to 10% by mole. Preferably it is mol%. A more preferable range is 20 to 80 mol% of the ethylene repeating unit and 80 to 20 mol% of the propylene repeating unit.

Further, the Mooney viscosity ML of BPR (at 100°C) is preferably in the range of 1 to 120, more preferably 5 to 100.

Furthermore, in the present invention, ethylene-butene copolymer rubber (
BBR) means that the content of butene-1 is 10 to 90% by weight.
A block copolymer having a butene-1 content of 20 to 80% by weight is particularly preferred.

Mooney viscosity ML of the above ethylene-butene copolymer rubber,
, (100°C) is preferably in the range of 1-120, more preferably 5-100.

In addition, the above ethylene-propylene copolymer (t!PR)
and ethylene-butene copolymer rubber (BBR) basically consist of the above-mentioned repeating units, but may contain other resin components within the range that does not impair the properties of these copolymer rubbers. can be used.

Further, the above ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber may be used alone or in combination.

The content of (b) ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber as described above is 3
0 to 40% by weight, preferably 32 to 38% by weight.

If the content exceeds the above upper and lower limits, it will be difficult to sufficiently reduce the coefficient of linear expansion of the injection molded product.

In addition, in the present invention, the blending ratio of (a) polypropylene and c) ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber as described above is the weight ratio ((b) / (a ) must exceed 0.5. If the above weight ratio is 0.5 or less, it becomes difficult to make the coefficient of linear expansion sufficiently low, especially in the longitudinal direction (MO force direction).The preferred range of the weight ratio is 0.5 to 1.
．． 2, particularly preferably 066 to 1.0.

In the present invention, talc is added as an inorganic filler to (a) and (b) as described above.

In the present invention, talc has an average particle size of 1 to 15. CN is preferred.

The content of the above talc is 10 to 30% by weight, preferably 1
It is 2 to 25% by weight. If the talc content is less than 10% by weight, the coefficient of linear expansion will increase, while if it exceeds 30% by weight, the impact resistance will decrease.

Further, in the present invention, whiskers can be added together with the above-mentioned talc for the purpose of further lowering the coefficient of linear expansion in the MO force direction.

In the present invention, the whisker is not particularly limited, but basic magnesium sulfate whiskers, potassium titanate whiskers, aluminum borate whiskers, and the like are preferred.

The length of the whisker is preferably 5 to 100 m, and the diameter is preferably 0.1 to 1 ρ.

The amount of the whiskers to be added is not set independently, but is related to the above-mentioned talc content, and is added in such a range that the whisker/talc weight ratio is 0.5 or less. When the whisker/talc ratio exceeds 0.5, the anisotropy becomes too large and the coefficient of linear expansion in the width direction (TO force direction becomes large).The preferable weight ratio is 0.1 to 0.5.

However, if whiskers are included, the total amount of talc + whiskers is 10 to 30, similar to the talc content above.
It is necessary that the amount is within the range of % by weight. If the content of talc + whiskers is less than 10% by weight, the coefficient of linear expansion will increase, while if it exceeds 30% by weight, the impact resistance will decrease. The preferred talc+whisker content is 12-25% by weight.

In addition, when whiskers are included, the talc content is 10
-20% by weight is preferred, particularly 12-15% by weight. Also, the maximum whisker content is 10% by weight (talc is 20% by weight, talc + whiskers is 30% by weight).
weight%).

The polyolefin resin composition of the present invention may also contain other additives for the purpose of modification, such as heat stabilizers, antioxidants, light stabilizers, flame retardants, plasticizers, antistatic agents, mold release agents, A blowing agent etc. can be added.

Such a composition of the present invention is prepared at 190 to 250°C, preferably 20°C using an extruder such as a single screw extruder or a twin screw extruder.
It can be obtained by melt-kneading at 0 to 230°C.

Moreover, the composition of the present invention obtained in this way is
The molded product obtained by injection molding at an injection temperature of 230°C has an average coefficient of linear expansion in the longitudinal direction (MD force direction) and the width direction (TD force direction) of 5.OXl0-'cm/cm.
/ is less than 4.5 x 10-'cII/cm/, especially in the longitudinal direction (MD force direction), which is a significantly lower value.

[For production]

The polyolefin resin composition of the present invention contains a predetermined amount of polypropylene, an ethylene-propylene copolymer rubber and/or an ethylene-butene copolymer rubber, talc, and whiskers as necessary, and comprises the polypropylene and the rubber. Since the blending ratio with the components is limited to a specific range, the injection molded product has a sufficiently low coefficient of linear expansion, and also has good impact resistance and mechanical strength.

The reason why such an effect is obtained is not necessarily clear, but by limiting each component to the range of the present invention and limiting the ratio of the rubber component to polypropylene to a specific range, each of the above components has a linear expansion coefficient. This is thought to be due to the optimum blending ratio in terms of impact resistance and mechanical strength.

〔Example〕

The present invention will be explained in further detail by the following examples.

The following materials were used as raw materials: polypropylene, ethylene-propylene copolymer rubber, talc, and whiskers.

[1] Polypropylene propylene-ethylene block copolymer BPP: [: BJ315 manufactured by Tonen Petrochemical ■, melt flow rate (MF
R, 230℃, 2.16kg load) 15g/10 minutes,
Ethylene content 7.0% by weight] [2] Ethylene-propylene copolymer rubber EPR: C Japan Synthetic Rubber ■Mouth PO2P, Mooney viscosity 24, Propylene content 26% by weight] [3] Talc: [Nippon Mistron■ Mistron 850-JS] [4] Whisker (i) Basic magnesium sulfate whisker Mg5W: [
MOSHIGE manufactured by Ube Industries ■] (10 Potassium titanate whisker TiKW + [Tismo manufactured by Otsuka Chemical ■) (B) Aluminum borate whisker^1! B: C Alborex G manufactured by Shikoku Kasei ■ Examples 1 to 12, Comparative example 1 ~5 Tri-blend polypropylene, ethylene-propylene copolymer rubber, talc, and whiskers if necessary in a super mixer at the blending ratios shown in Table 1, and then
The mixture was put into a twin-screw extruder manufactured by φ City and kneaded at 200°C to obtain pellets.

Next, the obtained pellets were molded into 350 mm x 100 mm at an injection temperature of 230°C using a 350Ton injection molding machine.
It was molded into a sheet of X 3 mo+.

The sheet thus obtained was measured for linear expansion coefficient, flexural modulus, tensile strength at break, and Izot impact strength. The results, along with the melt flow rate of the composition, are
Shown in the table.

(1) Coefficient of linear expansion: The sheet was left at -30°C, 23°C, and 80°C for 30 minutes, respectively, in the longitudinal direction (MD) and width direction (
Measure the dimensions of TO), and calculate the coefficient of linear expansion of each using the following formula.

Furthermore, the average value is Calculated by.

(2) MFR: 230℃ according to JIS K7210
, measured under a load of 2160 g.

(3) Flexural modulus: Measured according to JIS K7203.

(4) Tensile breaking strength: Measured according to JIS K7113.

(5) Izot impact strength knee at 30℃ JIS
Measured by K7110.

As is clear from Table 1, all injection molded products of the polyolefin resin composition of the present invention had an average linear expansion coefficient of 5.0 cm/cm/ or less. In particular, the linear expansion coefficient in the MD force direction was extremely low at 4.5 cm/cm/t. In addition, it was observed that the coefficient of linear expansion in the MD force direction tended to be lower in those containing whiskers together with talc. The compositions of each example had good flexural modulus, tensile strength at break, and Izot impact strength.

In contrast, the composition of Comparative Example 1 in which the weight ratio of polypropylene and ethylene-propylene copolymer rubber was 0.5 or less, the composition of Comparative Example 2 in which the content of ethylene-propylene copolymer rubber was too high, and The injection molded product of the composition of Comparative Example 3, which contained too little talc, had a large coefficient of linear expansion.

Furthermore, although the molded article of the composition of Comparative Example 4 containing an excessive amount of talc had a low coefficient of linear expansion, it had a low Izot impact strength value.

Furthermore, the molded article of the composition of Comparative Example 5 in which the weight ratio of whiskers to talc exceeds 0.5 had a low coefficient of linear expansion in the MD force direction, but a large coefficient of linear expansion in the TD direction.

〔Effect of the invention〕

As detailed above, the polyolefin resin composition of the present invention has a low coefficient of linear expansion in injection molded products, and has good impact resistance and mechanical strength.

Such a composition of the present invention is suitable for various automobile parts, such as EVA bumpers, side moldings, spoilers, mudguards, etc.

Applicant: Tonen Petrochemical Co., Ltd.

Claims (5)

[Claims] (1) (a) 30-60% by weight of polypropylene; (b)
) 30 to 40% by weight of ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber, and (c) 10 to 30% by weight of talc, wherein the (a) polypropylene and the (b) ethylene - A polyolefin resin composition characterized in that the weight ratio (b)/(a) of propylene copolymer rubber and/or ethylene-butene copolymer rubber is greater than 0.5. (2) (a) 30-60% by weight of polypropylene; (b)
) 30 to 40% by weight of ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber; (c) 10 to 30% by weight of talc and whiskers; ) ethylene-
The weight ratio (b)/(a) of the propylene copolymer rubber and/or ethylene-butene copolymer rubber is greater than 0.5, and the weight ratio (whisker/talc) of the talc and whiskers (c) is 0. .5 or less. (3) In the polyolefin resin composition according to claim 1 or 2, the weight ratio (b) of the (a) polypropylene and (b) ethylene-propylene copolymer rubber and/or ethylene-butene copolymer rubber /(a) is 0.5-1
．． 2. A polyolefin resin composition characterized by: (4) The polyolefin resin composition according to claim 2 or 3, wherein the whisker is one or more selected from basic magnesium sulfate whiskers, potassium titanate whiskers, and aluminum borate whiskers. polyolefin resin composition. (5) In the injection molded product of the polyolefin resin composition according to any one of claims 1 to 4, the temperature is 20 to 80°C.
The average coefficient of linear expansion in the longitudinal and width directions is 5 x 10^-
An injection molded product characterized by a temperature of 5cm/cm/℃ or less.