JPH062861B2 - Polypropylene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polypropylene resin composition having high rigidity, high molding fluidity, and excellent in coatability and especially low temperature impact resistance.

Conventionally, polypropylene resins have been widely used in various fields because of their excellent physical properties such as light specific gravity, high rigidity, and chemical resistance, but they have the drawback of being inferior in impact resistance at low temperatures. Therefore, a resin excellent in low temperature impact resistance has been developed by copolymerization with ethylene, and impact resistance and paintability have also been improved by blending ethylene-propylene copolymer rubber with a low propylene content. There is.

Further, it is generally practiced to further improve rigidity, heat resistance, dimensional stability, paintability and the like by blending various fillers with polypropylene resin.

However, at present, high rigidity, high heat resistance, easy paintability,
Along with high molding fluidity, high impact resistance and contradictory physical properties are required, and each has come to require high-level physical properties.

The various methods currently proposed for these purposes show sufficient physical property values for the requirements of one part, but the other physical properties are inferior. It must be said that it is not sufficient to meet the high physical property balance demanded by the market.

In addition, in order to satisfy various physical properties, it is necessary to increase the amount of rubber components, fillers, etc. added, or a specially treated one is required, and inevitably the price becomes high.

The present invention solves these drawbacks by providing a specific crystalline ethylene-propylene block copolymer, an ethylene-propylene copolymer rubber having a specific composition and viscosity, and an inorganic filler having a specified particle size. By adding a specified amount of the agent, a polypropylene resin composition having high rigidity, high molding flow, excellent coatability, and particularly low temperature impact resistance, and inexpensive is provided.

That is, the present invention is composed of the following components (a) to (c), and the proportion of each component is (a), (b):
0-65 parts by weight, (b) 10-35 parts by weight and (c) 2-2
The polypropylene resin composition is 5 parts by weight.

(a) Ethylene content 6 to 30% by weight, boiling n-heptane insoluble matter 75% by weight or more, tetralin solution (135 ° C.) intrinsic viscosity 1.2 to 2.0, melt flow index 8 or more crystalline ethylene-propylene block copolymer weight Coalescing.

(b) Propylene content is 40 to 60% by weight and 100 ° C.
An ethylene / propylene copolymer rubber having a Mooney viscosity of 15 to 80.

(c) An inorganic filler having a particle size of 6 μm or less.

The resin composition of the present invention has a physical property balance of high rigidity, low temperature impact resistance, high molding fluidity, excellent paintability, and is inexpensive, so that it can be used for large moldings such as automobile bumpers, fenders, and side moldings. Suitable for use in.

The propylene-ethylene block copolymer used in the present invention has an ethylene content of 6 to 30% by weight, a boiling n-heptane insoluble content of 75% by weight or more, a tetralin 135 ° C solution having an intrinsic viscosity of 1.2 to 2.0, and a melt flow rate. The index is 8 or more. When the above ethylene content is less than 6% by weight, the coatability of the obtained molded article decreases,
When it exceeds 30% by weight, the flexural modulus of the molded product becomes small. Further, when the n-heptane insoluble content of the polypropylene component is less than 75% by weight, the flexural modulus of the molded product becomes small, and when the intrinsic viscosity of the tetralin 135 ° C. solution is less than 1.20, the molded product has a When the low temperature impact strength becomes small, the melt flow index of the obtained polypropylene composition becomes small when it exceeds 2.0, and when the above melt flow index is less than 8, the melt flow index of the polypropylene composition obtained at the same time becomes small. The polypropylene resin composition becomes smaller, and in any case, the rigidity, impact resistance, and molding fluidity of the resulting polypropylene resin composition decrease, which is not preferable.

The ethylene / propylene copolymer rubber used in the present invention has a propylene content of 40 to 60% by weight and 100%.
It is limited to those having a Mooney viscosity of 15-80 at ° C. If the propylene content is less than 40% by weight, the appearance and low-temperature impact resistance of the molded product deteriorate, and if it exceeds 60% by weight, the flexural modulus and coatability of the resulting molded product deteriorate, which is not preferable. When an ethylene / propylene copolymer rubber having a Mooney viscosity of less than 15 or more than 80 is added to the crystalline ethylene-propylene block copolymer, the particle size of each dispersed ethylene / propylene copolymer rubber is small, or It is not preferable because it becomes too large and the physical properties of the resulting molded article are unbalanced.

Further, in the present invention, the blending amount of the ethylene-propylene copolymer rubber is such that the total amount of the crystalline ethylene-propylene block copolymer and the ethylene-propylene copolymer rubber is 1
10 to 35 parts by weight with respect to 00 parts by weight, impact resistance and paintability of the resulting composition deteriorate with a compounding amount of less than 10 parts by weight, and molding fluidity when the amount exceeds 35 parts by weight, The flexural modulus decreases, which is not preferable in any case.

The inorganic filler used in the present invention is a powdered inorganic filler, for example, calcium oxide, magnesium oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, magnesium carbonate, calcium silicate, magnesium silicate, calcium sulfate. , Calcium carbonate,
Examples thereof include barium sulfate, calcium sulfite, talc, clay, glass, basic magnesium carbonate, dolomite, and bilsonite, but calcium carbonate, barium sulfate, calcium silicate, and talc are particularly preferable.

Further, in the present invention, it is essential that the particle diameter of the inorganic filler used is 6 μm or less, and particularly preferably 5 μm or less. When an inorganic filler having a particle size of more than 6 μm is used, the impact resistance of the obtained polypropylene resin composition is lowered.

Regarding the particle size of the inorganic filler, there is a method of defining the unidirectional diameter, unidirectional equal area diameter, equal area diameter, Stokes diameter, etc., which are commonly used. It is measured by the measuring method of. The particle diameter in the present invention is an equal area diameter obtained by the light transmission method, and the measurement is performed by using, for example, a light transmission type particle size distribution measuring instrument manufactured by Seishin Enterprise Co., Ltd., model name SKC2000, and the like. The value obtained as the particle size (generally referred to as D ₅₀ ) can be used.

In the present invention, the addition ratio of the inorganic filler having a particle size of 6 μm or less is such that the resin component 10 comprising the crystalline ethylene / propylene block copolymer and the ethylene / propylene copolymer rubber is used.
It is in the range of 2 to 25 parts by weight with respect to 0 parts by weight. When the addition ratio of the inorganic filler is less than 2 parts by weight, the rigidity is not improved so much and the addition effect is small, which is not preferable. If added in excess of 25 parts by weight, the rigidity will be improved to some extent, but the impact resistance and paintability will be reduced, and especially the inorganic filler in the resin will absorb moisture and swell between the resin layer and the coating film. Therefore, the hot water resistance and the humidity resistance are deteriorated, which is not preferable.

Mixing of each component used in the polypropylene composition of the present invention, a single-screw extruder commonly used in the art, FC
It is carried out using a twin-screw extruder such as M or CIM.

An antioxidant that is generally added to polypropylene resins, as long as it does not significantly impair the effects of the present invention,
A heat stabilizer, an ultraviolet absorber, a flame retardant, a nucleating agent, an organic / inorganic pigment or the like may be used alone or in combination.

Hereinafter, the present invention will be specifically described with reference to examples. In the following description, the melt flow index is ASTM D-123.
8, flexural modulus is ASTM D-790, Izod impact value is ASTM
Measured according to D-256.

Example 1 Ethylene content 15% by weight, boiling n-heptane insoluble matter 9
3% by weight, tetralin 135 ° C. solution intrinsic viscosity 1.5, melt flow index 12, crystalline ethylene / propylene block copolymer (PP-A) 75 parts by weight, propylene content 50% by weight, Mooney viscosity at 100 ° C. 24 is ethylene-propylene copolymer rubber (EPR-A)
After adding 5 parts by weight of talc having a particle size of 1.3 μm as an inorganic filler to 100 parts by weight of the total amount of PP-A and ERP-A, and a small amount of other heat stabilizers, antioxidants, etc. The whole was mixed with a Henschel mixer and pelletized with an extruder. The obtained pellets were molded into a predetermined test piece using an injection molding machine, and each physical property value was measured.

The paintability was evaluated by the following method.

A test piece obtained by using an injection molding machine was coated with a two-component acrylic-chlorinated polypropylene undercoat paint having a film thickness of 10 μm.
And a two-component acrylic-urethane topcoat paint to a film thickness of 25 μm.
After drying at 90 ° C. for 30 minutes, it was left at room temperature for 24 hours to obtain a coatability test piece.

The coating film of this test piece is cut by a cutter with a length of 1 mm and a width of 1 mm
After cutting 100 grids, the cellophane tape was adhered, and then the cellophane tape was rapidly peeled off, and the initial adhesion was evaluated by the ratio of the grids of the remaining coating film (grid peeling test). Further, the coatability test piece was immersed in warm water at 40 ° C. for 240 hours, and then the hot water resistance was evaluated by observing the state of the coating film surface and peeling the cross-cut.

In addition, the pellets obtained above have a temperature of 30 ° C and a humidity of 90%.
After leaving for 1 week in the atmosphere of
A flat plate having a thickness of 0 mm × 80 mm × 2 mm was molded and the surface condition of the molded product was observed. The melt flow index of the obtained polypropylene resin, the flexural modulus of the test piece and the measured value of Izod impact strength, the evaluation result of the coating property and the surface condition of the molded product are shown in Table-1.

Example 2 In Example 1, the propylene content was 5 instead of EPR-A.
Tests were conducted in the same manner as in Example 1 except that 5% by weight of ethylene-propylene copolymer rubber (EPR-B) having a Mooney viscosity of 4.7 at 100 ° C. was used, and the obtained results are shown in Table 1. .

Example 3 In Example 1, in place of PP-A, the ethylene content was 14% by weight, the boiling n-heptane insoluble content was 85% by weight, the intrinsic viscosity of a tetralin 135 ° C. solution was 1.4, and the crystalline ethylene-propylene having a melt flow index of 35 was used. The same test as in Example 1 was carried out except that the block copolymer (PP-B) was used, and the obtained results are shown in Table 1.

Example 4 In Example 1, the amount of PP-A added was 80 parts by weight, EPR-A
Was tested in the same manner as in Example 1 except that the amount added was 20 parts by weight, and the results obtained are shown in Table 1.

Example 5 A test was performed in the same manner as in Example 1 except that the amount of talc used was changed to 2 parts by weight, and the obtained results are shown in Table 1.

Examples 6 to 8 In Example 1, barium sulfate having a particle size of 1.2 μm, calcium carbonate having a particle size of 1.9 μm, and calcium silicate having a particle size of 1.0 μm were replaced with talc used as an inorganic filler.
Compounded in the ratio shown in Table 1, and the obtained results are shown in Table-1.

Comparative Example 1 Table 2 shows the results obtained by the same test as in Example 1 except that the inorganic filler was not added in Example 1.

Comparative Example 2 In Example 1, the ethylene content was changed to 7.2 instead of PP-A.
% By weight, boiling n-heptane insoluble matter 93.8% by weight, tetralin 135 ° C. solution intrinsic viscosity of 2.4, crystalline ethylene-propylene block copolymer (PP-C) having a melt flow index of 1.6 was used. The results obtained by the same tests as in Table 2 are shown in Table 2.

Comparative Example 3 Example 3 was repeated except that the ethylene-propylene copolymer rubber (EPR-C) having a propylene content of 26% by weight and a Mooney viscosity of 24 at 100 ° C. was used instead of EPR-A. The test results obtained in the same manner as in Example 1 are shown in Table 2.

Comparative Example 4 Table-2 shows the results obtained by the same test as in Example 1 except that the talc having a particle size of 7 μm was used in place of the talc having a particle size of 1.3 μm used in Example 1.

Comparative Example 5 The results obtained by the same test as in Example 1 except that the addition amount of talc used in Example 1 was 30 parts by weight are shown in Table-2.

Comparative Example 6 Table 2 shows the results obtained by the same test as in Example 1 except that the amounts of PP-A and EPR-A used in Example 1 were each 50 parts by weight.

 ─────────────────────────────────────────────────── ─── Continuation of the front page Judge Masato Ikeda (56) References JP-A-53-64257 (JP, A) JP-A-57-55952 (JP, A) JP-A-58-32650 (JP, A) Special Kaisho 58-111846 (JP, A)

Claims (1)

[Claims] 1. A composition comprising the following components (a) to (c), wherein the proportion of each component is (a) 90 to 100 parts by weight based on the total amount of 100 parts by weight of (a) and (b):
A polypropylene resin composition comprising 65 parts by weight, (b) 10 to 35 parts by weight, and (c) 2 to 25 parts by weight. (a) Ethylene content 6 to 30% by weight, boiling n-heptane insoluble matter 75% by weight or more, intrinsic viscosity of tetralin solution (135 ° C) 1.
2 to 2.0, a crystalline ethylene-propylene block copolymer having a melt flow index of 8 or more. (b) An ethylene-propylene copolymer rubber having a propylene content of 40 to 60% by weight and a Mooney viscosity at 100 ° C. of 15 to 80. (c) An inorganic filler having a particle size of 6 μm or less.