JPH06100740A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic resin composition having excellent temporarily warping effect and vibration-damping properties. CONSTITUTION:A thermoplastic resin composition comprises (a) a polypropylene- based polymer having 3-20g/10 minutes melt index at 230 deg.C, (b) a polystyrenic resin and (c) a block copolymer composed of at least one polymer block A consisting essentially of a vinyl aromatic compound and at least one polymer block B consisting essentially of a conjugated diene compound, having 10-75wt.% content of the vinyl aromatic compound and is obtained by blending 100 pts.wt. total amounts of 60-99 pts.wt. component (a) and 1-40 pts.wt. component (b) with 1-20 pts.wt. component (c).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition having a low warpage effect and excellent vibration damping properties.

[0002]

2. Description of the Related Art Polypropylene resins are used for many purposes as inexpensive general-purpose resins having excellent mechanical strength and oil resistance. Another characteristic is that the material has a relatively large tan δ near room temperature and has a high vibration damping property. However, when it is used for a flat molded product, it largely warps, and it is often difficult to achieve the required dimensional accuracy.

Therefore, in order to reduce the warpage, alloying with a polystyrene resin which is an amorphous resin has been studied (Plastic Age Vol. 37, No. 3, p. 17).
5 (1991)). However, since polypropylene and polystyrene resin have poor compatibility with each other, even if they are mechanically mixed, only those having a low practical value can be obtained. In order to improve this drawback, a composition comprising a styrene-conjugated diene block copolymer and a hydrogenated block copolymer thereof has been proposed (JP-A-56-38338 and JP-A-64-38). 87645).

[0004]

However, the resin composition proposed above has a poor balance between mechanical strength, low warpage effect and vibration damping property, and is particularly excellent in low warp effect and vibration damping property. No composition has been obtained.

Therefore, an object of the present invention is to provide a thermoplastic resin composition having a low warp effect and excellent vibration damping properties.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that (a) a polypropylene resin having a specific melt index
We have found that a thermoplastic resin composition comprising (b) a polystyrene resin and (c) a block copolymer having a specific composition is excellent in low warpage effect and vibration damping property, and has completed the present invention.

That is, according to the present invention, the above objects are
(a) a polypropylene resin having a melt index of 3 to 20 g / 10 min at 230 ° C. under a load of 2.16 kg, (b) a polystyrene resin, and (c) at least one polymer block A mainly composed of a vinyl aromatic compound. Or more and at least one polymer block B mainly composed of a conjugated diene compound, and a block copolymer having a vinyl aromatic compound content in the range of 10 to 75% by weight, (a) 60 to 99 parts by weight of component, 1 to component (b)
40 parts by weight and a total of 10 of the components (a) and (b)
It can be achieved by a thermoplastic resin composition containing 1 to 20 parts by weight of the component (c) with respect to 0 parts by weight.

Examples of the polypropylene resin used as the component (a) of the present invention include polypropylene, ethylene-propylene copolymer, carboxyl-modified resin and silane-modified resin of these. Also,
It may be a mixture of these.

The melt index of the component (a) at 230 ° C. must be in the range of 3 to 20 g / 10 min. This melt index is 3g / 10m
When it is less than in or exceeds 20 g / min, the low warpage effect is not exhibited, which is not preferable.

Examples of the polystyrene resin used as the component (b) of the present invention include general-purpose polystyrene, high-impact polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, and the like. Also, a mixture of these may be used.

The melt index of the component (b) at 230 ° C. is preferably in the range of 1 to 30 g / 10 min.

In the thermoplastic resin composition of the present invention,
The ratio of the melt index at 230 ° C. of the polypropylene resin as the component (a) and the polystyrene resin as the component (b) preferably satisfies the range defined by the following formula (I). 0.1 ≦ α / β ≦ 2.0 (I) (wherein α represents the melt index of the polypropylene resin and β represents the melt index of the polystyrene resin).

In the thermoplastic resin composition of the present invention,
The polypropylene resin as the component (a) and the polystyrene resin as the component (b) are required to be used in a weight ratio of 60:40 to 99: 1, preferably 70:30 to.
The ratio is in the range of 95: 5. When the proportion of the polypropylene resin as the component (a) is less than 60, the vibration damping characteristic of the polypropylene resin is significantly deteriorated.

In the present invention, the block copolymer as the component (c) has at least one polymer block A mainly containing a vinyl aromatic compound and at least one polymer block B mainly containing a conjugated diene compound. A block copolymer having one or more and a vinyl aromatic compound content in the range of 10 to 75% by weight is used.

When the content of the vinyl aromatic moiety in the block A of the copolymer as the component (c) is less than 10% by weight, the rigidity may be lowered, and when it is more than 75% by weight, the content of (a)
The compatibility between the component and the component (b) may decrease, and various physical properties may decrease.

The vinyl aromatic hydrocarbon of the block A of the component (c) includes styrene, α-methylstyrene, o,
Examples thereof include m, p-methylstyrene and 2,4-dimethylstyrene, and styrene and α-methylstyrene are preferably used. As the conjugated diene of block B, isoprene, 1,3-butadiene, 2,3-dimethyl-1,3
-Butadiene, 1,3-pentadiene and the like are used, and isoprene, 1,3-butadiene and isoprene-butadiene are preferably used.

The conjugated diene polymer of the block B as the component (c) is preferably hydrogenated with 35% or more of the carbon-carbon double bonds in the block, and in view of heat resistance and weather resistance, Higher addition ratio is more preferable.

The block structure of the copolymer as the component (c) may be linear or branched. From the viewpoint of ease of production, an ABA type or an AB type structure is preferably used. The weight average molecular weight of the copolymer is preferably in the range of 3 × 10 ⁴ to 30 × 10 ⁴ .

The copolymer of component (c) can be produced by a known method, for example, the method described in JP-A-2-300250.

In the present invention, the block copolymer as the component (c) is used in an amount of 1 to 20 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of the total of the components (a) and (b). Be compounded. If the blending amount is too small, the compatibility between the component (a) and the component (b) will decrease, and if it is too large, the rigidity of the resin composition may decrease.

Glass fibers and flake fillers such as mica, graphite and glass flakes may be added to the thermoplastic resin composition of the present invention as long as the characteristics of the present invention are not impaired. In addition, a small amount of other additives such as antioxidants, ultraviolet absorbers, lubricants, pigments, plasticizers and the like may be added.

There is no limitation on the method of producing the composition of the present invention, such as a single screw extruder, a twin screw extruder, a kneader,
It can be produced by kneading with a kneading machine such as a Banbury mixer. When kneading, (a) component, (b)
It is preferable that sufficient kneading is performed so that the component and the component (c) are uniformly dispersed.

The thermoplastic resin composition of the present invention is not particularly limited in shape and can be formed into pellets by the above-mentioned method, or by a processing method such as injection molding, press molding, extrusion molding, for example, electric equipment housing, box shape. It can be a resin molded product that requires characteristics such as a low warp effect and a vibration damping property of a molded product and a propeller fan.

[0024]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, the following method was adopted as the test method for the evaluation items.

(1) Standard deviation of warp of disc A disc molded product was fixed, and an arbitrary 16 points on the disc were measured using a three-dimensional coordinate measuring machine (XYZAX manufactured by Tokyo Seimitsu Co., Ltd.). The reference plane was set, and the standard deviation of 16 points of deviation from the reference plane was determined.

(2) Tan δ Using a rod-shaped test piece with a width of 1 mm cut out from a molded product of 3 mm, the viscoelastic spectrum was measured by Rheovibron manufactured by Orientec Co., Ltd., and the value of tan δ at 25 ° C. was obtained.

(3) Notched Izod Impact Strength: A test piece having a thickness of 3 mm was used and determined according to JIS K-7110.

(4) Flexural modulus Using a test piece having a thickness of 6 mm, it was determined according to JISK-7203.

Example 1 75 parts of homopropylene (J-115G manufactured by Ube Industries, Ltd.) having a melt index of 230 ° C. (hereinafter sometimes abbreviated as MI) of 15 g / min,
Similarly, 25 parts of general-purpose polystyrene having an MI of 230 g at 10 g / min (Stylon 666 manufactured by Asahi Kasei Co., Ltd., which may be abbreviated as PS hereinafter), styrene-hydrogenated isoprene-styrene (ABA type) block copolymer ( Kuraray Septon KL-2104, which may be abbreviated as SEPS, hereinafter
(Styrene content 65% by weight, weight average molecular weight 7,000
0)) 5 parts were kneaded and pelletized by a twin-screw extruder under the condition of a cylinder temperature of 230 ° C. Using the pellets, a disk having a diameter of 15 cm, a bending test piece of 6 mm, and an Izod impact test piece of 3 mm were molded by an injection molding machine under the condition of a cylinder temperature of 230 ° C. The molded product was allowed to stand for 48 hours or more after molding, and then the above evaluation items were measured. Table 1
As shown in, shows a low warpage effect, vibration damping, impact resistance,
It can be seen that a molded product excellent in elastic modulus was obtained.

Example 2 90 parts of homopropylene (J-105G manufactured by Ube Industries, Ltd.) having an MI at 230 ° C. of 5 g / min and MI at 230 ° C.
Of 10 g / min for general-purpose polystyrene (Styron 666 manufactured by Asahi Kasei Corp.), styrene-hydrogenated isoprene-styrene block copolymer (Septon KL-2 manufactured by Kuraray Co., Ltd.)
104) 5 parts were used in the same manner as in Example 1 to obtain a molded product. The results of these evaluations are shown in Table 1. From this result, it can be seen that a molded product having a low warpage effect and excellent in vibration damping property, impact resistance and elastic modulus was obtained.

Example 3 75 parts of homopropylene (J-105G manufactured by Ube Industries, Ltd.) having an MI at 230 ° C. of 5 g / min and MI at 230 ° C.
Of 20 g / min of general-purpose polystyrene (Styron 679 manufactured by Asahi Kasei), styrene-hydrogenated isoprene-styrene block copolymer (Septon KL-2 manufactured by Kuraray Co., Ltd.)
104) 5 parts were used to obtain a molded product in the same manner as in Example 1. The results of these evaluations are shown in Table 1. From this result,
It can be seen that a molded product having a low warpage effect and excellent in vibration damping property, impact resistance and elastic modulus was obtained.

Example 4 65 parts of homopropylene (J-105G manufactured by Ube Industries, Ltd.) having an MI at 230 ° C. of 5 g / min and MI at 230 ° C.
Of 10 g / min of general-purpose polystyrene (Styron 666 manufactured by Asahi Kasei Corporation), styrene-hydrogenated isoprene-styrene block copolymer (Septon KL-2 manufactured by Kuraray Co., Ltd.)
104) 5 parts were used to obtain a molded product in the same manner as in Example 1. The results of these evaluations are shown in Table 1. From this result,
It can be seen that a molded product having a low warpage effect and excellent in vibration damping property, impact resistance and elastic modulus was obtained.

[0033]

[Table 1]

Comparative Example 1 Example 1 was prepared by using 100 parts of homopropylene (J-115G manufactured by Ube Industries, Ltd.) having an MI of 15 g / min at 230 ° C.
A molded product was obtained in the same manner as in. The results of these evaluations are shown in Table 2. The obtained molded product had a large warp.

Comparative Example 2 75 parts of homopropylene (J-105G manufactured by Ube Industries, Ltd.) having an MI at 230 ° C. of 5 g / min and MI at 230 ° C.
A molded article was obtained in the same manner as in Example 1 by using 25 parts of general-purpose polystyrene (Styron 666 manufactured by Asahi Kasei Co., Ltd.) of 10 g / min. The results of these evaluations are shown in Table 2. The obtained molded product had poor impact resistance.

Comparative Example 3 50 parts of homopropylene (J-105G manufactured by Ube Industries, Ltd.) having an MI at 230 ° C. of 5 g / min and MI at 230 ° C.
Of 10 g / min of general-purpose polystyrene (Styron 666 manufactured by Asahi Kasei), styrene-hydrogenated isoprene-styrene block copolymer (Septon KL-2 manufactured by Kuraray Co., Ltd.)
104) 5 parts were used to obtain a molded product in the same manner as in Example 1. The results of these evaluations are shown in Table 2. The obtained molded product did not have a low warpage effect, and was inferior in vibration damping property and impact resistance.

Comparative Example 4 75 parts of homopropylene (J-105G manufactured by Ube Industries, Ltd.) having an MI at 230 ° C. of 5 g / min and MI at 230 ° C.
Of 10 g / min for general-purpose polystyrene (Styron 666 manufactured by Asahi Kasei Corp.), styrene-hydrogenated isoprene-styrene block copolymer (Septon KL-2 manufactured by Kuraray Co., Ltd.)
104) 30 parts were used to obtain a molded product in the same manner as in Example 1. The results of these evaluations are shown in Table 2. The obtained molded product had a low elastic modulus.

Comparative Example 5 75 parts of homopropylene (J-130G manufactured by Ube Industries, Ltd.) having an MI at 230 ° C. of 30 g / min and M at 230 ° C.
25 parts of general-purpose polystyrene (Styron 666 manufactured by Asahi Kasei Corporation) having an I of 10 g / min, styrene-hydrogenated isoprene-
Styrene block copolymer (Kuraray Septon KL-
A molded article was obtained in the same manner as in Example 1 using 5 parts of 2104). The results of these evaluations are shown in Table 2. The obtained molded product had a large warp.

Comparative Example 6 75 parts of homopropylene (B-101H manufactured by Ube Industries, Ltd.) having an MI at 230 ° C. of 1 g / min and MI at 230 ° C.
Of 10 g / min for general-purpose polystyrene (Styron 666 manufactured by Asahi Kasei Corp.), styrene-hydrogenated isoprene-styrene block copolymer (Septon KL-2 manufactured by Kuraray Co., Ltd.)
104) 5 parts were used to obtain a molded product in the same manner as in Example 1. The results of these evaluations are shown in Table 2. The obtained molded product had a large warp.

[0040]

[Table 2]

[0041]

As described above, a thermoplastic resin composition comprising a polypropylene-based resin having a specific melt index, a polystyrene-based resin and a specific block copolymer is excellent in low warpage effect and vibration damping property, Moreover, it has excellent impact resistance and rigidity, and is useful for electric equipment housings, propeller fans, and the like.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area C08L 53:02) 7142-4J

Claims (2)

[Claims] 1. A heavy resin mainly composed of (a) a polypropylene resin having a melt index of 3 to 20 g / 10 min at 230 ° C. under a load of 2.16 kg, (b) a polystyrene resin, and (c) a vinyl aromatic compound. A block copolymer having at least one united block A and at least one polymer block B mainly composed of a conjugated diene compound, and having a vinyl aromatic compound content in the range of 10 to 75% by weight. 60 parts by weight of the component (a), 1 to 40 parts by weight of the component (b), and 1 part of the component (c) to 100 parts by weight of the total of the components (a) and (b).
A thermoplastic resin composition containing about 20 parts by weight. 2. The thermoplastic resin according to claim 1, wherein the ratio of the melt index at 230 ° C. of the polypropylene resin (a) and the polystyrene resin (b) satisfies the following formula (I). Resin composition 0.1 ≦ α / β ≦ 2.0 (I) (wherein α represents the melt index of the polypropylene resin and β represents the melt index of the polystyrene resin).