JP2770199B2 - Polyolefin resin composition and injection molded article thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyolefin resin composition and an injection-molded product thereof, and in particular, has a sufficiently small coefficient of linear expansion of the injection-molded product, and is suitable for a molding method and dimensional stability. The present invention relates to a polyolefin resin composition having excellent impact resistance and mechanical strength, and an injection-molded product thereof.

[Conventional technology]

Polypropylene is widely used in various fields because of its light weight and excellent mechanical strength. However, various polypropylene resins obtained by adding ethylene-propylene copolymer rubber (EPR), inorganic fillers, and the like to a propylene-ethylene block copolymer have been proposed for the purpose of improving the impact resistance. ing.

JP-A-61-12742 discloses (a) a propylene-based resin having an ethylene content of 2 to 3% by weight and a melt flow rate of 40 to 45 g / 10 minutes.
62-57% by weight of ethylene block copolymer, (b) ethylene content of 70-80% by weight, Mooney viscosity ML _{1 + 4} (100 ° C) 55-
26 to 28% by weight of 58 ethylene-propylene copolymer rubber,
(C) Density 0.955 to 0.960 g / cm ³ , melt flow rate 18
2-3% by weight of high-density polyethylene up to 22g / 10min, (d)
It is composed of 10 to 12% by weight of talc having an average particle size of 1.8 to 2.2 μm and a specific surface area of 36000 to 42000 cm ² / g.
18 g / 10 min, a density 0.950~0.980g / cm ^3, flexural modulus 11500～
14000kg / cm ² , Coefficient of linear expansion between 20 and 80 ° C 7 × 10 ^-5 to 10 × 1
0 ^-5 discloses resin composition characterized by cm / cm / ° C. is and JIS-Z8741 60 ° -60 ° surface glossiness of 55% or more by method.

JP-A-63-57653 discloses an inorganic filler composed of 100 parts of polypropylene, 20 to 50 parts of ethylene propylene rubber, 0 to 20 parts of talc, and 2.5 to 20 parts of whiskers. Disclosed is a resin composition characterized by containing an agent.

JP-A-63-95252, (a) having an ethylene content of 3 to 30% by weight and a melt index (MI) at 230 ° C of 4 g / 10
Min. Or more, a crystalline ethylene-propylene block copolymer of 40 to 80% by weight, (b) a propylene-ethylene block copolymer content of 10 to 90% by weight, and a Mooney viscosity ML _{1 + 4 at} 100 ° C (100 ° C 5) to 10% by weight of an ethylene-propylene copolymer rubber and / or an ethylene-propylene-diene terpolymer rubber wherein (c) is from 15 to 110, and (c) a surface treatment agent in a dry or semi-dry pulverizer. 2 to 25% by weight of surface-treated talc, (d) 2 to 25% by weight of barium sulfate having an average particle diameter of 1 μm or less, (e) Columnar or needle-like having an average particle diameter of 5 μm or less and an aspect ratio of 2.5 or more 1 to 10% by weight of calcium carbonate, and (f) nucleating agent 0.01 to
It discloses a resin composition comprising 0.5% by weight (based on the total amount of the above components (a) to (e)).

JP-A-1-118557 discloses a resin composition characterized by mixing 5 to 15% by weight of potassium titanate whiskers in a resin composition in which a polypropylene resin and an ethylene propylene rubber are mixed. I have.

Further, JP-A-1-149845 discloses that (a) 5 to 12% by weight of a boiling xylene-soluble component having an ethylene content of 20 to 60% by weight.
A propylene-ethylene block copolymer having an ethylene content of 1 to 7% by weight and a melt flow rate of 15 to 50 g / 10 minutes, 59 to 74% by weight, and (b) a propylene content of 20 to 60%. Weight% and Mooney viscosity ML _{1 + 4} (100
℃) 100-150 ethylene-propylene copolymer rubber
Disclosed is a resin composition comprising 35 to ²⁰ % by weight and (c) 3 to 6% by weight of talc having a specific surface area of 30,000 cm ² / g or more and an average particle size of 0.5 to 2.0 μm. doing.

[Problems to be solved by the invention]

However, JP-A-61-12742 and JP-A-63-95252
No., JP-A-1-149845 resin composition is 6 × 10 ^-5 cm / cm /
℃ ° C or higher, which tends to cause dimensional errors during assembly.For example, when used as a bumper, the bumper may have a different linear expansion coefficient from the vehicle body when placed in a high temperature environment. There is a problem in that it is easily deformed, which may impair the appearance.

The resin composition disclosed in JP-A-1-118557 has a low coefficient of linear expansion, but has a problem in that the impact resistance at low temperatures is poor.

Further, although the resin composition of JP-A-63-57653 has a low coefficient of linear expansion of 7 × 10 ⁻⁵ cm / cm / ° C. or less, the coefficient of linear expansion in the longitudinal direction (MD direction) of the injection-molded article is low. Yes, it's still not small enough. If the linear expansion coefficient in the longitudinal direction (MD direction) can be further reduced, the molding efficiency and assembling efficiency of various molded products can be advantageously improved.

Accordingly, an object of the present invention is to provide a polyolefin resin composition having a sufficiently small linear expansion coefficient, particularly a linear expansion coefficient in a longitudinal direction, of an injection-molded article, and having good impact resistance and mechanical strength, and an injection-molded article thereof. It is to be.

[Means for solving the problem]

As a result of intensive studies in view of the above problems, the present inventors have found that polypropylene and ethylene-propylene copolymer rubber and / or
Or in a composition comprising a predetermined amount of each of an ethylene-butene copolymer rubber and an inorganic filler such as talc,
An injection molded product of a resin composition in which the blending ratio of ethylene-propylene copolymer rubber and / or ethylene-butene copolymer rubber and polypropylene is limited to a specific range has a linear expansion coefficient, particularly a linear expansion in the longitudinal direction. The inventors have found that the rate is sufficiently small, and have reached the present invention.

That is, the first polyolefin resin composition of the present invention comprises: (a) 30 to 60% by weight of a propylene-ethylene block copolymer having an ethylene content of 5 to 15% by weight, and (b) ethylene-propylene copolymer. (C) 10 to 30% by weight of talc, and (b) ethylene relative to the (a) propylene-ethylene block copolymer. -The weight ratio [(b) / (a)] of the propylene copolymer rubber and / or the ethylene-butene copolymer rubber is 0.5 to 1.2.

Further, the second polyolefin resin composition of the present invention comprises: (a) 30 to 60% by weight of a propylene-ethylene block copolymer having an ethylene content of 5 to 15% by weight, and (b) an ethylene-propylene copolymer. A rubber and / or an ethylene-butene copolymer rubber in an amount of 30 to 40% by weight, and (c) talc and whiskers in an amount of 10 to 30% by weight. The weight ratio [(b) / (a)] of the ethylene-propylene copolymer rubber and / or the ethylene-butene copolymer rubber is 0.5 to 1.2, and the weight ratio of whisker / talc is 0.5 or less. Features.

Further, the injection molded article of the present invention comprising the above composition,
The linear expansion coefficient in the longitudinal direction at a temperature of 20 to 80 ° C. is 4.5 × 10
^-5 cm / cm / ° C. or less, and an average linear expansion coefficient in the longitudinal direction and the width direction is 5 × 10 ⁻⁵ cm / cm / ° C. or less.

 The present invention will be described in detail below.

The propylene-ethylene block copolymer used in the present invention has an ethylene content of 5 to 15% by weight. Further, the melt flow rate (MFR230 ° C., 2.16 kg load) is preferably 0.5 to 50 g / 10 min, and 9 to 30 g / 10 min.
More preferably, it is in the range of minutes.

The content of the propylene-ethylene block copolymer as described above is 30 to 60% by weight, preferably 37 to 56% by weight. 30% by weight of propylene-ethylene block copolymer
If it is less than 60%, the mechanical strength decreases. If it exceeds 60% by weight, it becomes difficult to sufficiently reduce the linear expansion coefficient of the injection molded product.

Note that the content of the propylene-ethylene block copolymer is not a value determined by itself, but as described later, the ethylene-propylene copolymer rubber and / or the ethylene-butene copolymer rubber has a specific weight. It is set to be a ratio.

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

The Mooney viscosity ML _{1 + 4} (100 ° C.) of EPR is preferably in the range of 1 to 120, more preferably 5 to 100.

In the present invention, the ethylene-butene copolymer rubber (EBR) is a block copolymer having a butene-1 content of 10 to 90% by weight, and particularly a butene-1 content of 20 to 90% by weight.
80% by weight is preferred.

Mooney viscosity ML of the above ethylene-butene copolymer rubber
_{1 + 4} (100 ° C.) is preferably in the range of 1 to 120,
More preferably, it is 5 to 100.

The above ethylene-propylene copolymer rubber (EP
R) and ethylene-butene copolymer rubber (EBR) are basically composed of the above-mentioned repeating units, but contain other resin components as long as the properties of these copolymer rubbers are not impaired. Things can also be used.

The ethylene-propylene copolymer rubber and / or ethylene-butene copolymer rubber may be used alone,
You may use both together.

The content of the above-mentioned (b) ethylene-propylene copolymer rubber and / or ethylene-butene copolymer rubber is
It is 30 to 40% by weight, preferably 32 to 38% by weight. If the content exceeds the above upper and lower limits, it becomes difficult to sufficiently lower the linear expansion coefficient of the injection molded article.

In the present invention, the weight ratio ((b) / (a)) of (a) ethylene-propylene copolymer rubber and / or ethylene-butene copolymer rubber to (a) propylene-ethylene block copolymer is as follows: 0.5 to 1.2. If the weight ratio is less than 0.5, it is difficult to sufficiently reduce the coefficient of linear expansion, particularly the coefficient of linear expansion in the longitudinal direction (MD direction). A preferred weight ratio range is 0.6 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 preferably has an average particle size of 1 to 15 μm.

The content of the talc is 10 to 30% by weight, preferably 12 to 30% by weight.
25% by weight. If the talc is less than 10% by weight, the coefficient of linear expansion increases, while if it exceeds 30% by weight, the impact resistance decreases.

In the present invention, whiskers can be added together with the above-described talc for the purpose of further reducing the coefficient of linear expansion in the MD direction.

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

The whisker preferably has a length of 5 to 100 μm, and a diameter of 0.1 to 1 μm.

The addition amount of the whisker is not set alone, but is related to the talc content described above, and is added in such a range that the weight ratio of whisker / talc is 0.5 or less. If the whisker / talc exceeds 0.5, the anisotropy becomes too large, and the coefficient of linear expansion in the width direction (TD direction) increases. The preferred weight ratio is between 0.1 and 0.5.

However, when whiskers are contained, the total amount of talc + whisker needs to be in the range of 10 to 30% by weight, similarly to the above-mentioned talc content. When the amount of talc + whisker is less than 10% by weight, the coefficient of linear expansion increases, while
If the content exceeds 10% by weight, the impact resistance is reduced. The preferred talc + whisker content is 12 to 25% by weight.

When whiskers are contained, the content of talc is 10
It is preferably from 20 to 20% by weight, particularly preferably from 12 to 15% by weight.
The maximum whisker content is 10% by weight (when talc is 20% by weight and talc + whisker is 30% by weight).

The polyolefin resin composition of the present invention has, for the purpose of modifying it, other additives such as a heat stabilizer, an antioxidant, a light stabilizer, a flame retardant, a plasticizer, an antistatic agent, a release agent, A foaming agent or the like can be added.

Such a composition of the present invention, using an extruder such as a single-screw extruder and a twin-screw extruder, at 190 to 250 ° C, preferably 200 to 230 ° C.
It can be obtained by melt-kneading at ℃.

In addition, the composition of the present invention obtained in this way is 210 to 2
A molded product obtained by injection molding at an injection temperature of 30 ° C. has an average linear expansion coefficient of 5.0 × 10 ⁻⁵ cm / cm / ° C. or less in the longitudinal direction (MD direction) and the width direction (TD direction). Yes, especially in the longitudinal direction (MD direction) is 4.5 × 10 ⁻⁵ cm / cm / ° C. or less, which is a significantly lower value.

(Operation)

Polyolefin resin composition of the present invention, propylene-
A predetermined amount of ethylene block copolymer, ethylene-propylene copolymer rubber and / or ethylene-butene copolymer rubber, talc, and, if necessary, whisker is contained, and the mixing ratio of the polypropylene and the rubber component Is limited to a specific range, the linear expansion coefficient of the injection molded product is sufficiently low, and the impact resistance and mechanical strength are also good.

Although the reason why such an effect can be obtained is not necessarily clear, while limiting each component to the scope 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. It is considered that this is because the mixing ratio becomes optimum in terms of impact resistance and mechanical strength.

〔Example〕

 The present invention is described in more detail by the following examples.

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

[1] Propylene-ethylene block copolymer BPP: [BJ315 manufactured by Tonen Petrochemical Co., Ltd., melt flow rate (MFR, 230 ° C., 2.16 kg load) 15 g / 10 min, ethylene content 7.0% by weight] [2] Ethylene-propylene copolymer rubber EPR: [Nippon Synthetic Rubber Co., Ltd. EP02P, Mooney viscosity 24,
Propylene content 26% by weight] [3] Talc: [Mistron manufactured by Nippon Mistron Co., Ltd.]
850-JS] [4] Whisker (i) Basic magnesium sulfate whisker MgSW: [Mos Heidi manufactured by Ube Industries, Ltd.] (ii) Potassium titanate whisker TiKW: [Tismo manufactured by Otsuka Chemical Co., Ltd.] (iii) Boric acid Aluminum whiskers AlB: [Arbolex G manufactured by Shikoku Chemicals Co., Ltd.] Examples 1 to 12, Comparative Examples 1 to 5 Propylene-ethylene block copolymer, ethylene-propylene copolymer rubber in the proportions shown in Table 1 Dry blend talc and whiskers as needed with a super mixer, then put into a 45 mm twin screw extruder,
Kneading was performed at 0 ° C. to obtain pellets.

Next, the obtained pellet is processed by a 350Ton injection molding machine.
It was formed into a 350 mm x 100 mm x 3 mm sheet at an injection temperature of 230 ° C.

For the sheet obtained in this way, the linear expansion coefficient,
The flexural modulus, tensile strength at break, and Izod impact strength were measured. The results are shown in Table 1 together with the melt flow rate of the composition.

(1) Linear expansion coefficient: The sheet was left at −30 ° C., 23 ° C., and 80 ° C. for 30 minutes to measure the dimensions in the longitudinal direction (MD) and the width direction (TD). Calculated by the formula.

Was calculated by

(2) MFR: Measured at 230 ° C under a load of 2160 g according to JIS K7210.

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

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

(5) Izod impact strength: JIS K7110 at -30 ° C
Measured by

As is clear from Table 1, the injection molded article of the polyolefin resin composition of the present invention had an average value of linear expansion coefficient of 5.0 cm / cm / ° C. or less. Especially the coefficient of linear expansion in the MD direction is
It was extremely low at 4.5 cm / cm / ° C. In addition, those containing whiskers together with talc tended to have a lower linear expansion coefficient in the MD direction. In addition, the composition of each Example had good bending elastic modulus, tensile breaking strength, and Izod impact strength.

In contrast, the weight ratio of ethylene-propylene copolymer rubber to propylene-ethylene block copolymer is
The injection-molded articles of the composition of Comparative Example 1 having a content of ethylene-propylene copolymer rubber of less than 0.5, the composition of Comparative Example 2 having too much content of ethylene-propylene copolymer rubber, and the composition of Comparative Example 3 having too little content of talc were linear. The expansion rate was large.

A molded article of the composition of Comparative Example 4 containing excessive talc had a low linear expansion coefficient, but a small value of Izod impact strength.

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

〔The invention's effect〕

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

Such a composition of the present invention is suitable for various automobile parts, for example, bumpers, side moldings, spoilers, mat guards and the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 23/16 C08L 23/16 (72) Inventor Isao Baba 3-1, Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa-ken Tonen Petrochemical Co., Ltd. Technology Development Center (72) Inventor Yoshiharu Saito 3-1 Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Tonen Petrochemical Co., Ltd. Technology Development Center (72) Inventor Masato Komatsu 3-6 Nishiki, Naka-ku, Nagoya-shi, Aichi 29 Tonen Petrochemical Co., Ltd. Nagoya Branch (56) References JP-A-2-182739 (JP, A) JP-A-63-57653 (JP, A) JP-A-62-91545 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C08L 23/00-23/36

Claims (4)

(57) [Claims] (1) An ethylene content of 5 to 15% by weight.
30-60% by weight of propylene-ethylene block copolymer
And (b) 30 to 40% by weight of an ethylene-propylene copolymer rubber and / or an ethylene-butene copolymer rubber; and (c) 10 to 30% by weight of talc. A polyolefin, wherein the weight ratio [(b) / (a)] of the ethylene-propylene copolymer rubber and / or the ethylene-butene copolymer rubber (b) to the block copolymer is 0.5 to 1.2. Resin composition. (A) the content of ethylene is 5 to 15% by weight;
30-60% by weight of propylene-ethylene block copolymer
And (b) 30 to 40% by weight of an ethylene-propylene copolymer rubber and / or an ethylene-butene copolymer rubber; and (c) 10 to 30% by weight of talc and whisker, The weight ratio [(b) / (a)] of the (b) ethylene-propylene copolymer rubber and / or ethylene-butene copolymer rubber to the ethylene block copolymer is 0.5 to 1.2, and whisker / A polyolefin resin composition, wherein the weight ratio of talc is 0.5 or less. 3. The polyolefin resin composition according to claim 2, wherein the whiskers are one or two or more selected from basic magnesium sulfate whiskers, potassium titanate whiskers, and aluminum borate whiskers. Polyolefin resin composition. 4. The injection molded article of the polyolefin resin composition according to claim 1, wherein a linear expansion coefficient in a longitudinal direction at a temperature of 20 to 80 ° C. is 4.5 × 10 ⁻⁵ cm / cm / ° C. An injection-molded article characterized by having an average linear expansion coefficient of 5 × 10 ⁻⁵ cm / cm / ° C. or less in the longitudinal direction and the width direction.