JPH05331330A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE:To obtain a polypropylene resin composition which can easily give a molding having easily improved vibration-damping properties in a high- temperature atmosphere and is less brittle for its high-rigidity. CONSTITUTION:The composition is prepared by adding a reinforcing inorganic filler to a resin component comprising a crystalline PP, a high-density PE and an aromatic hydrocarbon resin. The resin component further contains a hydrogenated aromatic vinyl/conjugated diene block copolymer (SEBS).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene resin composition. In particular, the present invention is suitable for a resin molded product that requires damping properties in a high temperature atmosphere.

Examples of the resin molded product include a timing belt cover around an engine of an automobile, a gear cover, an air cleaner case, a cylinder head cover and the like.

The following is a list of abbreviations used in this specification.

PE ... Polyethylene, PP ... Polypropylene SEBS ... Hydrogenated products of aromatic vinyl-conjugated diene block copolymers.

MI (melt index) ... at 190 ° C.
211. When the force of 82 N is applied, the amount of resin extruded from the orifice of diameter 2.1 mm φ x 8 mm L (g number (JIS K 7210
reference).

[0006] In the present specification, the compounding unit is a weight unit unless otherwise specified.

[0007]

2. Description of the Related Art As a molding material for a resin molded article as described above, PP and PE, which are the lightest and relatively well-balanced physical properties among resin materials, and which are inexpensive, are used as base polymers. A polypropylene resin composition having the following constitution was filed by the applicant of the present application and is disclosed in JP-A-2-28.
It is disclosed as Japanese Patent Application No. 1056 (Japanese Patent Application No. 1-104129).

"(A) Crystalline polypropylene resin 37-
92% by weight and (B) polyethylene resin 5 to 60% by weight
And (C) an aromatic hydrocarbon resin in an amount of 3 to 30% by weight. "

[0009]

With the recent demands for higher temperature and less noise in the engine room, further improvement of the vibration damping performance in the high temperature atmosphere is required for the above resin molded products. It started to come.

Further, compared with the improvement of the vibration damping performance, the rigidity and the high degree of impact resistance, that is, the toughness is large (the amount of energy until the material breaks is large) and the low brittleness (deformation before the material break down). It has become necessary to be large).

However, based on the above resin composition,
When an inorganic filler is blended, sufficient vibration damping performance at high temperatures may not be obtained, and the impact resistance is lower than the rigidity, and the brittleness tends to be particularly high.

In view of the above, the object of the present invention is to easily improve the vibration damping performance in a high temperature atmosphere, and
It is intended to provide a polypropylene-based resin composition capable of easily forming a molded article having a low brittleness as compared with rigidity.

[0013]

Means for Solving the Problems The inventors of the present invention have earnestly made efforts to solve the above problems, and as a result, have conceived a PP resin composition having the following constitution.

In a PP-based resin composition prepared by adding a reinforcing inorganic filler to a resin component obtained by adding and mixing crystalline PP with high-density PE and an aromatic hydrocarbon resin, a resin component is further added as a resin component. The aromatic hydrogen-conjugated diene block copolymer hydrogenated product (SEBS) is added and mixed.

[0015]

[Detailed Description of Means] Next, a detailed description will be given of each configuration of the above means.

(1) As the crystalline PP, propylene homopolymer or propylene-ethylene copolymer (ethylene content is usually 20% or less regardless of random block)
It is possible to use a general-purpose PP such as. Here, for these general-purpose PP, modified PP having a carboxyl group introduced, etc.
It is desirable to mix and use it in the range of%.

The crystalline PP usually has MI = 5 to 5
Use 0 g / 10 minutes (desirably 10-40 g / 10 minutes). When the MI is less than 5 g / 10 minutes, the moldability and the appearance of the molded product are likely to be deteriorated, and 50 g / 10
If it exceeds the minute, the impact resistance tends to be adversely affected.

Here, the blending ratio of the crystalline PP in the resin component is usually 50 to 97%, preferably 60 to 80%. If it is less than 50%, it is difficult to maintain the strength and heat resistance of the molded product (see Comparative Example 3), and if it exceeds 97%, the blending ratio of other resin components becomes too small, and it is difficult to expect the effect of the present invention.

(2) As the high-density PE, it is possible to use one having a weight average molecular weight of tens of thousands to hundreds of thousands produced by the medium pressure method or the low pressure method. At this time, a medium density PE, a low density PE, a linear low density PE, or a plurality of types of these may be used together.

The blending ratio of high-density PE is usually 1 to 30.
%, Preferably 5 to 20%. When medium density / low density PE is used in combination, the proportion thereof is usually 60% or less.

If the high density PE is too small, the effect of improving the vibration damping performance at high temperature cannot be expected, and if it is too high, the strength and
The heat resistance is relatively reduced. Further, it is desirable to use only high-density PE from the viewpoint of balancing rigidity and vibration damping property (see Examples 2 to 9 in Table 2).

(3) The aromatic hydrocarbon resin is styrene,
It means one having a copolymer structure of a polymerizable aromatic compound such as indene or coumarone, or one containing them as a main component.

Specifically, the softening point (ring and ball type: JIS K 220
7, the same below) 80-170 ° C, preferably 100-1
Examples thereof include aromatic petroleum resins, coumarone-indene resins and the like at 40 ° C., or a mixture thereof with a phenol resin and a rosin resin.

Of these, aromatic petroleum resins having good reinforcing properties are particularly desirable, and more specifically, "Nisseki Neopolymer 120" (manufactured by Nippon Petrochemical Co., Ltd.) and "Petrogin 100. 120/130 "(Mitsui Petrochemical Co., Ltd.)
Manufactured by K.K.), “Escorez 3102”, and the like.

The blending ratio of the aromatic hydrocarbon resin in the resin component is usually 1 to 20%, preferably 5 to 15%.

If the amount of the aromatic hydrocarbon resin is too small, the effect of improving the vibration damping performance of the molded article cannot be expected, and if it is too large, the strength and heat resistance are relatively lowered.

(4) The reinforcing inorganic filler is not particularly limited, but from the viewpoint of imparting impact resistance, it is desirable to use a fibrous and powdery filler together.

Examples of the fibrous filler include glass fiber, carbon fiber, metal fiber (whisker) and asbestos.

Examples of the powdery and granular filler include talc, calcium carbonate, silica, clay, fly ash, hollow glass body, mica, barium sulfate and the like.

Of these, a combination of glass fiber and talc is particularly preferable.

The amount of the above-mentioned filler compounded is the total amount of fibrous and powdery particles, and is usually 10 to 1 per 100 parts of the resin component.
The amount is 00 parts, preferably 20 to 60 parts. Here, the fibrous filler and the granular filler are the former / the latter = 5/5 to 1
/ 9.

If the compounding amount of the inorganic filler is too small, the effect of improving the mechanical properties such as rigidity, heat resistance and strength of the molded product cannot be expected, and if it is too large, it has a negative effect on the vibration damping performance. It is easy to have an influence. Further, if the amount of the fibrous filler is too small, the effect of improving the impact resistance, rigidity and heat resistance cannot be expected, and if the amount of the fibrous filler is too large, the vibration damping performance is likely to be negatively affected.

(5) The hydrogenated product of an aromatic vinyl-conjugated diene block copolymer is generally abbreviated as SEBS, which is a block copolymer of an aromatic vinyl such as styrene and a conjugated diene such as butadiene. A polymer in which a conjugated diene polymer portion is hydrogenated and saturated. And a commercially available molecular weight of 30,000 to 70,000 and styrene content of 20
Any of up to 40% can be used. Among these,
A compound having an average molecular weight of 50,000 and a styrene content of 20% is desirable from the viewpoint of reducing brittleness (see Example 3).

Specifically, "Tuftec H-105
2 "(manufactured by Asahi Kasei Co., Ltd.)," Clayton G1657 "(manufactured by Shell Chemical Co.) and the like.

The mixing ratio of the SEBS in the resin component is
1 to 20%, preferably 2 to 10%.

If SEBS is too small, the effect of the present invention,
It is difficult to expect low brittleness of molded products, and conversely, if too much,
The mechanical properties of the molded product such as rigidity and heat resistance are likely to be adversely affected.

(6) The above composition can be prepared using an ordinary kneader such as a single-screw extruder, a twin-screw extruder, a kneader, a Brabender, a Banharley mixer and the like. Normally,
Tumbler blender with each blending component in a predetermined ratio,
Mix with a Henshur mixer, ribbon mixer, etc.
Then, the mixture is kneaded with an extruder or the like to obtain a pellet-shaped molding material. Using the material, a resin molded product such as a timing belt cover and a gear cover is manufactured by injection molding or the like.

When glass fibers are mixed in the above composition, glass fiber reinforced PP granules can be used.

In the present invention, in addition to the above components, additives such as an antioxidant, an ultraviolet absorber, a lubricant, an antistatic agent, a nucleating agent, a pigment, a flame retardant, a filler, a processing aid and the like are mixed. May be.

[0040]

As described above, the PP resin composition of the present invention comprises a reinforcing inorganic filler in a resin component obtained by adding and mixing crystalline PP with high-density PE and an aromatic hydrocarbon resin. In the PP-based resin composition prepared by blending SEBS with SEBS as a resin component, a high temperature is obtained as compared with a conventional olefin-based resin composition, as shown in Examples described later. It becomes easy to improve the vibration damping performance of the above, and at the same time, it becomes easy to meet the demand for the improvement of impact resistance, especially the reduction of brittleness.

Therefore, the PP resin composition of the present invention can be used as a molding material for parts in an engine room of automobiles, interior parts, exterior parts, and other electric and mechanical parts.
In particular, it is suitable for parts that generate vibration noise in the engine room of an automobile, such as a timing belt cover, a gear cover, and an air cleaner case.

[0042]

EXAMPLES Examples and comparative examples according to the present invention will be described below.

A. Preparation of Test Pieces Mixtures of each compounding recipe (total amount 100%) shown in Tables 1 and 2 were mixed with a twin-screw extruder (L / D of each screw = 27, 30).
Was melt-kneaded to prepare a pellet molding material.

The resin component blends and inorganic fillers used in each of the examples and comparative examples are as follows.

Crystalline PP, glass fiber ... "Hipol J
-800 "(homo PP) and" FRPP-E-7000 "
Prepared by mixing with (homo PP containing 30% glass fiber).
All made by Mitsui Petrochemical Industry Co., Ltd. High-density PE ... "Ace Polyethylene F6080V" Showa Denko KK Low-density PE ... "Mirason 67" Mitsui Petrochemical Industry Co., Ltd.
SEBS made ... "Tuftec H1052" Asahi Kasei Corporation
Aromatic petroleum resin: "Nisseki Neopolymer 120" manufactured by Nippon Petrochemical Co., Ltd. Talc: "LMR100" manufactured by Fuji Talc Co., Ltd. A test piece was molded by an injection molding machine using the above pellet material. The injection conditions are cylinder temperature: 220 ° C,
Mold temperature: 40 ° C.

B. Test method For each test piece, the tests of the following items were performed.

(1) Flexural Modulus and Flexural Strength A test was conducted according to ASTM D790.

(2) Heat distortion temperature According to ASTM D648, a load of 450.8 KPa (4.6 k)
The test was performed at gf / cm ² ).

(3) Izod Impact Value A test piece with a machined notch was tested according to ASTM D256.

(4) Bending Deflection In the above Izod impact test, the following variables were measured and determined by the following formula.

D (bending bending amount) = 6 h · Vt / L ² where h: sample thickness (cm), V: bending speed (cm / min)
), T: time to break (min), L: distance between fulcrums (cm).

(5) Loss coefficient A square flat plate having a length of 150 mm and a width of 3 mm and a thickness of 3 mm was prepared by injection molding, and the central portion of the flat plate was set to 0. The transfer function was measured by vibrating at 1G. Then, the loss coefficient η was calculated from the primary resonance point by the half-width method.

C. Test Results and Evaluation From the test results shown in Table 1, Examples 1 to 6 of the present invention in which high density / low density PE are used in combination are superior to Comparative Example 1 in vibration damping performance at high temperature. With Izod
It can be seen that the impact value is large, the bending deflection is large, and the impact resistance is good.

From the test results shown in Table 2, it is understood that when only high-density PE is used as the PE, the vibration damping performance is further improved as compared with the case where the low-density PE is used together. Further, it is understood that Examples 7 to 9 have a large bending deflection amount and low brittleness as compared with Comparative Example 2.

[0055]

[Table 1]

[0056]

[Table 2]

Claims (1)

[Claims] 1. A high density polyethylene (PE) and an aromatic hydrocarbon resin are added to crystalline polypropylene (PP).
A polypropylene resin composition in which a reinforcing inorganic filler is mixed with the mixed resin component, and as the resin component, a hydrogenated product of an aromatic vinyl-conjugated diene block copolymer is further added and mixed. A polypropylene-based resin composition comprising: