GB2249550A

GB2249550A - Reinforced polypropylene resin composition

Info

Publication number: GB2249550A
Application number: GB9123528A
Authority: GB
Inventors: Shigeji Ichikawa; Katsunori Arai; Hideyo Morita; Kouhei Ueno; Tatsushi Akou
Original assignee: Kansei Corp; Ube Industries Ltd
Current assignee: Marelli Corp; Ube Corp
Priority date: 1990-11-08
Filing date: 1991-11-06
Publication date: 1992-05-13
Anticipated expiration: 2011-11-06
Also published as: JPH04175354A; GB2249550B; CA2054975A1; GB9123528D0; JP2829121B2; DE4136687A1

Abstract

A reinforced polypropylene resin composition comprising, based on the total weight of the composition, the total amount of the components (b) and (c) being 2 to 14%. (a) 45 to 75% by weight of a polypropylene modified with an organosilane compound or an unsaturated acid, or of said modified polypropylene together with an unmodified polypropylene; (b) 1 to 10% by weight of a noncrystalline ethylene- alpha -olefin copolymer; (c) 1 to 10% by weight of a styrenic hydrogenated block copolymer; (d) 2 to 12% by weight of a glass fibre having a moan fibre diameter of 4 to 15m mu ; and (e) 15 to 35% by weight of a hard mica having a tensile strength of 30 kg/mm<2> or more, a mean particle diameter of 50 to 250 m mu and an aspect ratio of 15 to 80. The composition may also contain a nucleating agent in an amount of from 0.2 to 1.0 pan per 100 parts by weight of the composition.

Description

) "D.; 5 -)

DESCRIPTION REINFORCED POLYPROPYLENE RESIN COMPOSITION

The present invention relates to a reinforced polypropylene resin composition suitable particularly for instrument panels. More particularly, the present invention is concerned with a reinforced polypropylene resin composition having a good moldability and such well balanced properties that when it is molded into an article, the molded article has a tensile strength, a flexural modulus, a flexural strength, a hardness, a falling ball impact strength and other properties sufficient for practical use and is excellent in other properties and less susceptible to warpage deformation while maintaining. rigidity and impact resistance at a high temperature.

In order to improve the mechanical strength, rigidity, heat deformation resistance and other properties, it is a common practice to incorporate into polypropylene various fillers, for example, fibrous fillers such as glass fibers, carbon fibers, whiskers or metallic fibers, flakv fillers such as mica, talc, kaolinite or glass flake, and particulate -2fillers such as calcium carbonate, diatomaceous earth, alumina or glass beads. This method has already found wide applications.

Among the above-described fillers in various forms, fibrous fillers exhibit a much better reinforcing effect than do fillers in the other forms. Polypropylene resin compositions reinforced with glass fibre have found wide use in various fields as materials suitable for the production of molded articles having high rigidity and high heat resistance.

However, when a glass-fibre reinforced polypropylene resin composition is molded into particularly a large-sized article, whilst the product is free from problems in respect of rigidity and heat resistance, it is liable to exhibit a larger "warpage" (deformation). This is a problem encountered when glass-fibre reinforced polypropylene resin compositions are used as molding materials for largesized molded articles.

On the other hand, the use of a flaky filler and a particulate filler as a filler for the polypropylene resin reduces the warpage deformation. In this case, however, the reinforcing effect on the tensile strength, flexural modulus, flexural strength, Izod impact resistance and thermal rigidity is much smaller than that is the case where use is made of a fibrous filler. Nevertheless, since an article moulded from a polypropylene resin composition reinforced with a flaky filler, such as mica or talc, exhibits good rigidity, an attempt has been made to combined the use of a fibrous filler and a flaky filler. This is disclosed in, for example, Japanese Patent Laid-Open Nos. 36141/1977, 130647/1979, 16049/1980, 21438/1980, 45715/1980, 206659/1983, 226041/1984, 23432/1985 and 98758/1986.

Even the inventions disclosed in the above-described documents, however, cannot provide any molded article satisfying the requirements tor warpage and torsion.

An object of the present invention is to provide a reinforced polypropylene resin composition having a good moldability and such wellbalanced properties that when it is molded into an article, the molded article has a tensile strength, a flexural modulus, a flexural strength, a hardness, a falling ball impact strength and other properties sufficient for practical use and is excellent in other properties and less susceptible to warpage deformation while maintaining rigidity and impact resistance at a high temperature.

It has now been found that a reinforced polypropylene resin composition capable of attaining the above-described object can be obtained by incorporating a mica in a particular form and a particular elastomer each in a particular amount into a glass-fibre reinforced polypropylene resin.

The present invention provides a reinforced polypropylene resin composition comprising, based on the total weight of the composition:

(a) 45 to 75% by weight of a polypropylene modified with an organosilane compound or an unsaturated acid, or of said modified polypropylene together with an unmodified polypropylene; (b) 1 to 10% by weight of a noncrystalline ethylene-a-olefin copolymer; (c) 1 to 10% by weight of a styrenic hydrogenated block copolymer; (d) 2 to 12% by weight of glass fibre having a mean fibre diameter of 4 to 15 my; and (e) 15 to 35% by weight of a hard mica having a tensile strength of 30 kg/MM2 or more, a mean particle diameter of 50 to 250 mp and an aspect ratio of 15 to 80, the total amount of said components (b) and (c) being 2 to 14%.

The modified polypropylene of component (a) is one modified with an organosilane compound or an unsaturated acid and can be prepared by subjecting polypropylene and an organosilane compound or an unsaturated acid to a melt kneading treatment in the presence of an organic peroxide.

When component (a) contains both modified polypropylene and unmodified polypropylene the amount of the modified polypropylene in component (a) is preferably such as to provide at least 20% by weight based on the total weight of the composition. When the amount of the modified polypropylene is less than 20% by weight, there is a fear of both the rigidity and the impact resistance becoming insufficient.

The organosilane compound used for preparing the modified polypropylene may be an organosilane compound having an ethylenically unsaturated bond, such as a vinyl group, an allyl group or a methacryloxy group, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (P- methoxyethoxy) silane and "Il'methacryloxypropyltrimethoxysilane. An unsaturated acid may be used instead of the -6organosilane compound. Examples of the unsaturated acid include unsaturated carboxylic acids and their anhydrides, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, citraconic acid, maleic anhydride and itaconic anhydride.

In the present invention, a crystalline ethylenepropylene block copolymer having an ethylene content of 2 to 20% by weight, preferably 3 to 15% by weight, may be used as the polypropylene constituting component (a). When the ethylene content exceeds 20% by weight, the rigidity becomes insufficient, while when the ethylene content is less than 2% by weight, there is a fear of the impact resistance becoming insufficient.

In the present invention, the amount of the organosilane compound or unsaturated acid preferably ranges from 0.01 to 3 parts by weight, more preferably from 0.3 to 1 part by weight, based on 100 parts by weight of the crystalline ethylenepropylene block copolymer. When this amount exceeds 3 parts by weight, the appearance of the molding is liable to become poor, while when it is less than 0.01 part by -7weight, it is difficult to improve the properties.

It is preferred that the decomposition temperature for attaining a halflife period of one minute of the organic peroxide used for preparing the modified polypropylene be 200'C or below. Examples of organic peroxides of this type include tert-butyl peroxybenzoate, tert-butyl peroxymaleic acid, tert-butyl peroxylaurate, cyclohexanone peroxide, 2,5-dimethyl-2,5di(benzoylperoxy)hexane, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, dicumyl peroxide, 2,5dimethyl2,5-di(tert-butyl-peroxy)hexane, tert-butyl cumyl peroxide and ditert-butyl peroxide.

The amount of the organic peroxide is preferably 0.05 to 1 part by weight based on 100 parts by weight of the crystalline ethylene-propylene block copolymer.

Polypropylene and the organosilane compound or the unsaturated acid may be subjected to a meltkneading treatment to prepare a modified polypropylene by various known methods. one simple and favorable method comprises adding the organosilane compound or unsaturated acid and the organic peroxide to polypropylene, agitating and mixing them by means of a Henschel mixer or the like, and melt kneadina the mixture preferably at a temperature of 180 to 250'C for 1 to 20 min through the use of an extruder.

The amount of component (a) is 45 to 75% by weight. When this amount is less than 45% by weight, the moldability becomes poor, while when it exceeds 75% by weight, the balance between the rigidity and the impact resistance becomes poor.

The noncrystalline ethylene-a-olefin copolymer as the component (b) is preferably one which has an ethylene content of 30 to 80% by weight and a Mooney viscosity MI'1+4 (1000C)t Of 10 to 150 Examples of the non crystalline ethylene-a-olefin copolymer include ethylene-propylene rubber, ethylenebutene-1 rubber, ethylene-propylene-butene rubber, ethylenepropylenediene rubber, and ethylene-butemediene rubber. The amount of said non crystalline copolymer is preferably 1 to 8% by weight based on the total weight of the composition.

SEBS, SEPS, etc., are preferably used as the styrenic hydrogenated block copolymer of component (c) of the present invention. They are commercially available under the trade names of Kraton G (Shell Kagaku Co. , Ltd.), Taftec (Asahi Chemical Industry Co., Ltd.) and Septon (Kuraray Co., Ltd.). The amount of the styrenic copolymer is preferably 1 to 8% by weight based on the total weight of the composition.

In the present invention, the total amount of the components (b) and (c) is 2 to 14% by weight, preferably 2 to 10% by weight. When the total amount is less than 2% by weight, the warpage becomes excessively large. On the other hand, when it exceeds 14% by weight, the rigidity becomes insufficient. The glass fibre as the component (d) of the present invention may be chopped glass strand or glass roving such as those produced and commercially available for the reinforcement of resins, may have a mean fibre diameter and a mean fibre length of 4 to 15 mp and 2 to 15 mm, respectively, most preferably 6 to 13 my and 2 to 5mm, respectively, for achieving rigidity and impact resistance. When the mean fibre diameter is less than 4mp, the fibre is broken during the kneading, so that the rigidity is lowered. On the other hand, when it exceeds 15mp, the glass fibre comes up on the molded article. When the mean fibre length is less than 2mm, the rigidity becomes insufficient. on the other hand, when it exceeds 15mm, the dispersibility is lowered, so that the appearance of the molded article becomes poor.

The glass fibre is preferably one subjected to surface treatment with a coupling agent such as an aminosilane compound, an epoxysilane compound, a vinylsilane compound or a methacrylosilane compound.

The mean fibre length of the glass fibre in the final moulded article is preferably 0.5mm or more. For this purpose, it is desirable to produce a glass fibre-reinforce polypropylene by a method wherein the melt kneading is conducted through the use of an extruder provided with a feedstock supply port at its cylinder in addition to an ordinary feedstock supply port while feeding the components (a), (b), (c) and (e) from the ordinary feedstock supply port and feeding the component (d) from the feedstock supply port provided at the cylinder.

The amount of the glass fiber is 2 to 12% by weight, preferably 3 to 10% by weight. When this amount is less than 2% by weight, the rigidity becomes insufficient, while when it exceeds 12% by weight, the warpage becomes excessively large.

The hard mica as the component (e) of the present invention should have a tensile strength of 30 kg/mm2 or more and a mean particle diameter of 50 to 250 mp.

2 When-the tensile strength is less than 30 kg/mm ' the rigidity of the molded article becomes insufficient. When the mean particle diameter is less than 50 mi, the rigidity of the molded article becomes insufficient and the warpage becomes excessively large, while when it 250 mi, the impact resistance becomes insufficient.

There is no particular limitation on the variety of mica to be used in the composition of the present invention provided that the tensile strength, mean particle diameter and aspect ratio fall each within the above-described range, and the mica may be selected from a wide variety of mica such as biotite, muscovite and phlogopite.

Further, the mica to be used in the present invention may be one not subjected to any surface treatment or one subjected to a surface treatment with various surface treatments.

The mica is used in an amount of 15 to 35% by weight. When this amount is less than 15% by weight, the rigidity becomes insufficient, while when it exceeds 35% by weight, the impact resistance becomes insufficient.

In order to shorten the molding cycle in the injection molding of the composition of the present invention, it is preferred to incorporate 0.1 to 1. parts, preferably 0.2 to 1.0 part, of a nucleating agent in 100 parts of the composition of the presen invention. Since the nucleating agent deforms the molded article, it has not hitherto usually been used when alleviation of the deformation is intended. Since the incorporation of a nucleating agent was known to enhance the rigidity but lower the impact resistance, nucleating agents have hitherto been used for materials having a low rigidity. When a nucleating agent is incorporated in the composition of the present invention however, there are obtained quite unexpected results such that a composition having a high rigidity and a short molding cycle can be prepared without detriment to the impact resistance.

In the composition of the present invention, the above-described components may be used in combination with various additives, for example, antioxidants, ultraviolet absorbers, antistatic agents, heat-resistant materials, nucleating agents and pigments.

The present invention will now he described in more detail with reference to the followina Examples and Comparative Examples, though it is not limited to these only.

In order to evaluate the effect of the present invention, the properties were evaluated by the following methods.

-13Evaluation Methods Used in Examples and Comparative Examples 1. Melt flow rate (MFR) Determined according to JIS K7210 (230'C). 2. Flexural strength (FS) Determined according to JIS K7203 (23'C) 3. Flexural modulus (FM) Determined according to JIS K7203 (23'C). 4. Izod impact resistance (notched) Determined according to JIS K7110 (23'C). 5. Heat deformation temperature (HDT) Determined according to JIS K7207 (load: 18. 5 kg/cm 2).

6. Degree of warpage deformation A flat plate having a thickness of 2 nim, a longitudinal length of 360 mm and a lateral length of 160 mm with a single-point gate (a side gate) provided at a position 75 mm inside from the end in the longitudinal direction was prepared by injection molding for use as a test piece. It was allowed to stand at a temperature of 230C and a humidity of 50% for 48 hr and put on a platen to measure the distance (height) from both ends of the test piece to the platen, and the average distance value was determined.

7. Aspect ratio The aspect ratio was calculated from the mean particle diameter and mean thickness.of the mica.

- Mean particle diameter of mica Particle size distribution was measured through the use of a JIS sieve by means of a Model 200 LS air jet sieve, manufactured By Alpine, while the mean particle diameter was determined from the diameter on a logarithmic probability paper. Mean thickness of mica The mean thickness was measured from the area of a monomolecular film by Kyodai Arakawa. method.

- Mean aspect ratio The mean aspect ratio was calculated by the following equation:

mean particle diameter mean aspect ratio = mean thickness 8. Molding cycle The molding cycle of expressed by the shortest molding cycle in the case where an instrument panel having a length of 1400 mm, a height of 300 mm, a width of 450 mm and a weight of 3.5 kg is injectionmolded (molding machine: 2500 tons, Toshiba Kikai IS-250ODN, molding temperature: 230'C).

9. Heat deformation resistance The instrument panel was irradiated with infrared rays from an infrared lamp (Model T-10S manufactured by Tabai Espec Corp.) for 4 hr in such a manner that the surface temperature of the instrument panel and the atmosphere temperature reached 115 3'C and 80 2'C, respectively, and then allowed to stand at room temperature.

Then, whether or not the degree of deformation (upward and downward) of the front end (garnish) of the instrument panel is larger than the reference value (3 mm) was determined.

G: a degree of deformation of 3 mm or less, NG: a degree of deformation of more than 3 mm.

10. Impact resistance An aluminum head form (1650, 6.8 kg) was impacted against the instrument panel at a speed of 24 km/hr according to FMVSS201, ECE No. 21 (testing apparatus: Model AI-150P, manufactured by Itoh Seiki Co., Ltd.). The impact resistance was evaluated based on whether or not the test piece can satisfy a requirement that the generation acceleration rate does not exceed 80 g for 3 msec or more without interruption and a requirement that no sharp edge occur on the impact face.

G: satisfied, ro NG: not satisfied. Example 1 100 parts by weight of a crystalline ethylenepropylene block copolymer having a MFR value of 1 g/10 min and an ethylene content of 7.6% by weight was mixed with 0.3 part by weight of itaconic anhydride, 0.15 part by weight of tert-butyl peroxybenzoate, 0.1 part of 2,6-di-tert-butyl-4-methylpheno1 and 0.1 part of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4hydroxyphenyl)propionatel, and the mixture was meltkneaded in a single-screw extruder at 200C for 2 min to give a modified polypropylene grafted with itaconic anhydride (hereinafter referred to as "modified PP-1") having an MFR value of 12 g/10 min.

65% by weight of the modified PP-1, 3% by weight of an ethylene-propylene copolymer having an ethylene content of 75% by weight and a Mooney viscosity ML1+4 (100'C) of 70 (hereinafter referred to as "EPR"), 2% by weight of Kraton G1650 (a product of Shell Kagaku Co., Ltd.; hereinafter referred to as I'St-l") as a styrenic hyerogenated block copolymer and 25% by weight of a mica having a tensile strength of 34 kg/mm 2, a mean particle diameter of 140 mii and a mean aspect ratio of 64 (a product of Repco; hereinafter referred to as "mica-l") were sufficiently mixed with -17each other in a tumbler and fed into an ordinary feedstock supply port of a twin-screw extruder equipped with two feedstock supply ports, while 5% by weight of a chopped strand glass fiber having a diameter of 10 mv and a length of 3 mm and subjected to surface treatment with 0.3% by weight of an aminosilane (a product of Nippon Electric Glass Co., Ltd.; hereinafter referred to as "GF") was fed after being metered from another feedstock supply port provided at the cylinder. The mixture was melted, kneaded, extruded at a temperature of 230 to 240'C, and pelletized. The resultant pellets were injection-molded to prepare a test piece for use in various evaluation tests. The evaluation test results are given in Table 1.

Example 2

The procedure of the Example 1 was repeated, except that the proportions of the modified PP-1, EPR, St-1 and GF were changed to 59% by wight, 1% by weight, 7% by weight and 8% by weight, respectively. The evaluation test results are given in Table 1.

Example 3

The procedure of the Example 1 was repeated, except that the proportion of the modified PP-1 was changed to 30% by weight, 30% by weight of a crystalline ethylene-propylene block copolymer having a MFR value of 9 g/10 min and an ethylene content of 7.5% by weight (hereinafter referred to as "PP") was added, the proportions of the St-1, GF and mica-1 were changed to 3% by weight, 6% by weight and 28% by weight, respectively, and 0.4 part by weight, based on 100 parts by weight of the whole components including 3% by weight of EPR, of a nucleating agent (aluminum p-tert butylbenzoate) was added. The evaluation test results are given in Table 1.

Example 4

The procedure of the Example 3 was repeated, except that the proportion of the unmodified PP was changed to 32% by weight, Septon 2003 (a product of Kuraray Co., Ltd.; hereinafter referred to as "St-2") was used as the styrenic hydrogenated block copolymer in an amount of 3% by weight and the proportions of FPR and GF were changed to 2% by weight and 5% by weight, respectively. The evaluation test results are given in Table 1.

Example 5

The procedure of the Example 4 was repeated, except that the amount of the nucleating a gent was changed to 0.8 part by weight based on 100 Darts by weight of the whole components wherein the proportions -19of the modified PP-1, unmodified PP, EPR, St-2, GF, mica-1 and a mica having a tensile strength of 39 2 kg/mm '. a mean particle diameter of 60 mij and a mean aspect ratio of 37 (a product of Repco; hereinafter referred to as "mica-2") were 25% by weight, 47% by weight, 1% by weight, 1% by weight, 4% by weight, 12% by weight and 10% by weight, respectively. The evaluation test results are given in Table 1.

Example 6

The procedure of the Example 1 was repeated, except that 0.5 part by weight of y-methacryloxypropyltrimethoxysilane was used instead of itaconic anhydride used in the Example 1 and 0.25 part by weight of tertbutyl peroxybenzoate was used, thereby preparing a modified polypropylene having a MFR value of 15 g/10 min grafted with a silane (hereinafter referred to as "modified PP-2"). Then, the procedure of the Example 5 was repeated, except that use was made of 38% by weight of the modified PP-2 instead of the modified PP-1 used in the Example 5, 14% by weight of the unmodified PP, 7% by weight of FPR, 2% by weight of St-I instead of St-2, 6% by weight of GF, 10% by weight of mica-1, 23% by weight of mica 2 and 0.5% by weight of a nucleating agent. The evaluation test results are given in Table 1.

Comparative Example 1 The procedure of the Example 1 was repeated, except that the proportions of GF and mica-1 were changed to 15% by weight and 15% by weight, respectively. The evaluation test results are given in Table 2.

Comparative Example 2 The procedure of the Example 1 was repeated, except that the proportions of the modified PP-1 and St-1 were changed to 60% by weight and 10% by weight, respectively, and no EPR was added. The evaluation test results are given in Table 2.

Comparative Examples 3 and 4 The procedure of the Example 1 was repeated, except that in Comparative Example 3, the proportion of mica-1 was changed to 30% by weight and no GF was added, and in Comparative Example 4, the proportions of the modified PP-1 and mica-1 were changed to 50% by weight and 40% by weight, respectively. The evaluation test results are given in Table 2.

Comparative Examples 5 and 6 The -Procedure of the Example 4 was repeated, except that in Comparative Example 5, the proportion of the modified PP-1 was 35% by weight and neither EPR nor St2 was added, and in Comparative Example 6, a -21mica-3 having a tensile strength of 18 kg/mm 2, a mean particle diameter of 160 mp and a mean aspect ratio of 65 (manufactured by Repco) was used instead of mica-1. The evaluation test results are given in Table 2.

Comparative Example 7 The procedure of the Example 1 was repeated, except that the proportion of EPR used in the Example 1 was changed to 5% by weight and no St-1 was used. The evaluation test results are given in Table 2.

Table 1

Ex. No.

1 2 3 4 5 6 modified PP-1 65 59 30 30 25 modified PP-2 - - - - - 38 unmodified PP 30 32 47 14 EPR 3 1 3 2 1 7 mixing St-1 2 7 3 - - 2 ratio St-2 - - - 3 1 - ratio) (wt GF 5 8 6 5 4 6 mica-1 25 25 28 28 12 10 mica-2 - - - - 10 23 nucleating agent - - 0.4 0.4 0.8 0.5 MFR (g/IQ min) 3.5 3.2 4.5 4.7 5.1 3.6 F (kg /CM2) 682 700 705 697 631 710 FM (kg/ CM2) 40,500 42,800 44,000 43,200 39,300 43,900 Izod (kg-cm/cm) 11.5 12.0 10.0 10.6 8.4 10.3 HDT (OC) 122 125 127 126 120 125 evalution warpage 0.12 0.33 0.20 0.19 0.21 0.10 deformation (mm) molding cycle 82 88 76 76 70 77 (sec) heat deformation G -G G G G G resistance impact G G G G G G resistance I NJ Nj I modified PP-1 modified PP-2 unmodified pp F- P R mixing ratio (wt: ratio) evaluatin Table 2

COMP. Ex. No.

nucleating agent MFR (g/10 min) FS (kg/cm') FM (kg/cml) Izod (kg. cm/cm) 3. 4 3.3 3.6 758 46,500 12.6 HDT (C) 130 warpage deformation (MM) molding cycle (sec) heat deformation resistance impact resistance 3.1 583 35,100 13.5 4.8 83 NG 615 36,300 8.0 0.11 86 NG 764 51,000 768 650 49,600 40,200 6.0 9.0 6.3 119 128 134 0.10 0.11 2.9 88 85 75 77 G G G G G NG NG NG 124 0.53 NG G 1 m (A 1 668 39,600 10.0 118 0.36 84 NG G The reinforced polypropylene resin composition of the present invention has such well-balanced properties that when it is molded into an article, the molded article has a tensile strength, a flexural modulus, a flexural strength, a hardness, a falling ball impact strength and other properties sufficient for practical use and is excellent in other properties and less susceptible to warpage deformation. In particular, when the reinforced polypropylene composition of the present invention is molded into a large-sized article, the molded article exhibits "warpage" significantly alleviated to such an extent as will bring about no problem in practical use as compared with the molded article prepared from the conventional polypropylene composition reinforced with a glass fiber.

Thus, the reinforced polypropylene composition of the present invention have attained the object unattainable by the conventional glass fiberreinforced polypropylene composition, that is, the object of alleviating the "warpage" without lowering the strength and heat resistance of 1-he molded article. For example, the reinforced polypropylene composition of the present invention is useful particularly as a reinforced polypropylene resin -25composition having a good moldability suitable for the production of a molded article used in applications where a molded article having a large size and being less susceptible to deformation is required, for example, core materials of instrument panels for automobile parts.

The reinforced polypropylene composition according to the present invention can be molded into having a high rigidity, a high heat and a high impact resistance at a high temperature and a very small warpage deformation, which renders the composition of the present invention very suitable as a core material of an instrument panel for automobiles.

an article resistance

Claims

-26CLAIMS

1. A reinforced polypropylene resin composition characterised by comprising based on the total weight of the composition:

(a) 45 to 75% by weight of a polypropylene modified with an organosilane compound or an unsaturated acid, or of said modified polypropylene together with an unmodified polypropylene; (b) 1 to 10% by weight of a noncrystalline ethylene-a-olefin copolymer; (c) 1 to 10% by weight of a styrenic hydrogenated block copolymer; (d) 2 to 12% by weight of a glass fibre having a mean fibre diameter of 4 to 15 my; and (e) 15 to 35% by weight of a hard mica having a tensile strength of 30 kg/mm2 or more, a mean particle diameter of 50 to 250 my and an aspect ratio of 15 to 80, the total amount of said components (b) and (c) being 2 to 14%.

2. A reinforced polypropylene resin composition according to claim 1, characterised in that a nucleating agent is used in an amount of 0.1 to 1. 5 parts by weight based on 100 parts of the total amount of said components (a) to (e).

3. A reinforced polypropylene resin composition -27according to claim 1 or 2, characterised in that the polypropylene constituting said component (a) is a crystalline ethylene-propylene block copolymer having an ethylene content of 2 to 20% by weight.

4. A reinforced polypropylene resin composition according to any of claims 1 to 3, characterised in that said component (b) is a noncrystalline ethylene-a-olefin copolymer having an ethylene content of 30 to 80% by weight and a Mooney viscosity ML1+4 (1000C) of 10 to 150.

5. A reinforced polypropylene resin composition according to claim 4, wherein said noncrystalline ethylene-a-olefin copolymer is ethylenepropylene rubber, ethylene-butene-1 rubber, ethylene-propylenebutene rubber, ethylene-propylene-diene rubber or ethylene-butene-diene rubber.

6. A reinforced polypropylene resin composition according to any of claims 1 to 5, characterised in that said component (c) is SEBS or SEPS.

7. A reinforced polypropylene resin composition according to any of claims 1 to 6, characterised in that said component (d) is a glass fibre which has been subjected to a surface treatment with a coupling agent selected from the group consisting of an aminosilane compound, an epoxysilane compound, a vinylsilane compound and a methacrylosilane compound.

--------------------------------------------------------------