Disclosed is a glass fiber-reinforced composition, which comprises (A) 99-40 wt. % of a modified ethylene/propylene block copolymer having a polar monomer content of at least 0.05 wt. %, which is obtained by graft-modifying at least partially a crystalline ethylene/propylene block copolymer, in which the ethylene content is 3-15 wt. %, the melt flow rate is 0.1 to 70 g/10 min, the intrinsic viscosity of the portion soluble in p-xylene at normal temperature is 2.5-6 as measured in decalin at 135.degree. C. and the ethylene content of the portion insoluble in p-xylene at normal temperature is 1.5-10 wt. %, with a polar monomer and an organic peroxide in an extruder, (B) up to 20 wt. % of a polyolefin rubber, and (C) 1 to 45 wt. % of a surface-treated glass fiber. This composition gives a molded article having an excellent rigidity and impact resistance.

cl BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
The present invention relates to a glass fiber-reinforced polypropylene 
composition which gives a molded article having excellent rigidity and 
impact resistance. 
(2) Description of the Related Art 
Polypropylene has ekcellent physical and chemical properties and is widely 
used for electric appliances, construction materials, automobile parts, 
and parts of various machines. 
In fields where high rigidity is required, various fillers are incorporated 
into polypropylene, and in fields where an especially high rigidity is 
necessary, glass fiber-reinforced polypropylene is used. 
Glass fiber-reinforced polypropylene is unsatisfactory in touch and 
appearance because the glass fiber rises on the surface of a molded 
article, the gloss of the surface is poor, and the surface is rough and 
gritty. Further, the impact resistance is low, and accordingly, the 
commercial value is low. 
To improve the physical properties of glass fiber-reinforced polypropylene, 
a resin composition has been proposed wherein polypropylene grafted with 
maleic anhydride is substituted for the polypropylene (see Japanese 
Examined Patent Publication No. 51-10265). This resin composition, 
however, has a low impact resistance and accordingly, the commercial value 
is low. 
Accordingly, to improve the impact resistance of a molded article of glass 
fiber-reinforced polypropylene, a composition has been proposed in which a 
linear amorphous rubbery polymer is incorporated into polypropylene (see 
Japanese Examined Patent Publication No. 59-2294). This composition 
comprises 40 to 85 parts by weight of crystalline polypropylene grafted 
with a polar vinyl monomer or other crystalline polyolefin, 5 to 50 parts 
by weight of a glass fiber, and 5 to 35 parts by weight of a linear 
amorphous rubbery elastomer. However, this composition is not preferred 
from the practical viewpoint because the composition has a poor impact 
resistance, especially a drop weight impact strength which is an important 
factor in practice. 
SUMMARY OF THE INVENTION 
It is a primary object of the present invention to solve the 
above-mentioned problems involved in the conventional glass 
fiber-reinforced polypropylene compositions and provide a composition that 
can give a glass fiber-reinforced polypropylene molded article having high 
rigidity and high impact resistance, especially a high drop weight impact 
resistance. 
More specifically, in accordance with the present invention, there is 
provided a glass fiber-reinforced polypropylene composition, which 
comprises, based on the total weight of the composition, (A) 99 to 40% by 
weight of a modified ethylene/propylene block copolymer having a polar 
monomer content of at least 0.05% by weight, which is obtained by 
graft-modifying at least a part of a crystalline ethylene/propylene block 
copolymer, in which the ethylene content is 3 to 15% by weight, the melt 
flow rate is 0.1 to 70 g/10 min, the intrinsic viscosity of the portion 
soluble in p-xylene at normal temperature is 2.5 to 6 as measured in 
decalin at 135.degree. C. (the same will apply hereinafter) and the 
ethylene content of the portion insoluble in p-xyIene at normal 
temperature is 1.5 to 10% by weight, with a polar monomer and an organic 
peroxide in an extruder, (B) up to 20% by weight of a polyolefin rubber, 
and (C) 1 to 45% by weight of a surface-treated glass fiber. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
According to the present invention, since graft modification can be carried 
out in an extruder even though a crystalline ethylene/propylene block 
copolymer is used in substitution for polypropylene, a polypropylene 
composition having an excellent rigidity and impact resistance can be 
obtained by a simple operation. 
In the present invention, a modified ethylene/propylene block copolymer 
which is at least partially graft-modified with a polar monomer and has a 
polar monomer content of at least 0.05% by weight is used in substitution 
for the polypropylene. The polyolefin used in the present invention for 
obtaining the modified ethylene/propylene block copolymer is a crystalline 
ethylene/propylene block copolymer in which the ethylene content is 3 to 
15% by weight, the melt flow rate (MFR) is 0.1 to 70 g/10 min, preferably 
0.3 to 20 g/10 min (ASTM D-1238, 230.degree. C., 2160 g), the intrinsic 
viscosity of the portion soluble in p-xylene at normal temperature 
(preferably in an amount of 5 to 25% by weight) is 2.5 to 6, preferably 3 
to 5, and the ethylene content of the portion insoluble in p-xylene at 
normal temperature (preferably in an amount of 75 to 95% by weight) is 1.5 
to 10% by weight, preferably 3 to 7% by weight. If the total ethylene 
content or the ethylene content of the portion insoluble in p-xylene at 
normal temperature is too low and below the above-mentioned range, the 
impact resistance of the obtained composition is low. In contrast, if the 
ethylene content exceeds the upper limit, the ethylene component is 
crosslinked during the graft modification carried out in an extruder, and 
the impact resistance is reduced and the appearance of the molded article 
degraded. If the intrinsic viscosity of the portion soluble in p-xylene at 
normal temperature is lower than the lower limit, the impact resistance of 
the composition is low. In contrast, if this intrinsic viscosity is higher 
than the upper limit, crosslinking is readily caused in an extruder and 
the impact resistance of the obtained composition is reduced. It is 
difficult to prepare polypropylene having an MFR lower than the 
above-mentioned lower limit, and if the MFR exceeds the upper limit, 
pelletization after the graft modification in an extruder is difficult and 
handling is not easy. 
The crystalline ethylene/propylene block copolymer is graft-modified by 
melt-mixing the copolymer with a polar monomer and an organic peroxide in 
an extruder, preferably at 175.degree. to 280.degree. C. for about 1 to 
about 20 minutes. 
The polar monomer is not particularly critical. Unsaturated carboxylic 
acids and their functional derivatives, such as itaconic anhydride, maleic 
anhydride, acrylic acid and derivatives thereof can be mentioned. Of 
these, itaconic anhydride is preferred. 
The organic peroxide is not particularly critical. An organic peroxide in 
which the decomposition temperature giving a half value period of 1 minute 
is not lower than the melting point of the crystalline ethylene/propylene 
block copolymer used and not higher than 220.degree. C. is preferred. For 
example, there can be mentioned t-butyl peroxybenzoate, cyclohexanone 
peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butyl peroxyacetate, 
methyl ethyl ketone peroxide, dicumyl peroxide and 
2,5-dimethyl-2,5-di(t-butylperoxy)hexane. 
Preferably, the graft polymerization can be accomplished by mixing 100 
parts by weight of the crystalline ethylene/propylene block copolymer with 
0.05 to 3 parts by weight of the polar monomer and 0.002 to 1 part by 
weight of the organic peroxide and melt-kneading the mixture in nitrogen 
or air. It is preferred that pelletization be carried out after the graft 
modification in the extruder. The resultant graft-modified 
ethylene/propylene block copolymer may be used as it is or after it has 
been mixed with the above-mentioned unmodified ethylene/propylene block 
copolymer so that the polar monomer content in the mixture is at least 
0.05% by weight, preferably 0.05 to 1% by weight. It is preferred that the 
MFR of the thus-obtained modified ethylene/propylene block copolymer be 1 
to 150 g/10 min. 
In the present invention, a polyolefin rubber may be incorporated. As the 
polyolefin rubber, there can be preferably used an ethylene/propylene 
copolymer rubber (EPR) having an ethylene content of about 30 to about 80% 
by weight, an ethylene/propylene/nonconjugated diene copolymer rubber 
(EPDM), and an ethylene/butene- 1 copolymer rubber. Of these, the 
ethylene/propylene copolymer rubber is most preferable. The polyolefin 
rubber may be graft-modified with a polar monomer as mentioned above. The 
method for introducing the polar monomer by graft modification is not 
particularly critical. For example, the introduction can be accomplished 
according to a solution method or heat-kneading method using a radical 
initiator such as an organic peroxide as mentioned above. It is preferred 
that the polar monomer be grafted to the polyolefin rubber for the 
modification in an amount of 0.05 to 3.5% by weight. After the graft 
modification, the graft-modified polyolefin rubber can be recovered 
according to known procedures. It is preferred that the ML.sub.1+4 value 
(100.degree. C.) of the graft-modified polyolefin rubber be in the range 
of from 10 to 100. 
In the present invention, a surface-treated glass fiber is used. The shape 
or length of the glass fiber is not particularly critical. A chopped 
strand having a diameter of 3 to 30.mu. and a length of 2 to 10 mm, or a 
roving, may be used. As the surface-treating agent used for the surface 
treatment, there can be mentioned vinyltriethoxysilane, 
vinyltris(.beta.-methoxyethoxy)silane, 
.gamma.-methacryloxypropyltrimethoxysilane, 
.gamma.-glycidoxypropyltrimethoxysilane, 
n-(dimethoxymethylsilylpropyl)ethylenediamine, 
n-(triemthoxysilylpropyl)ethylenediamine, 
.gamma.-aminopropyltriethoxysilane and 
.gamma.-aminopropyltrimethoxysilane. It is preferred that the amount of 
the surface-treating agent be 0.05 to 3% by weight. A commercially 
available surface-treated glass fiber may be used as it is. 
The mixing ratios of the respective components in the glass 
fiber-reinforced polypropylene composition are such that the amount of the 
modified ethylene/propylene block copolymer (A) is 99 to 40% by weight, 
preferably 85 to 50% by weight, the amount of the polyolefin rubber (B) is 
up to 20% by weight, preferably 3 to 20% by weight, and the amount of the 
surface-treated glass fiber (C) is 1 to 45% by weight, preferably 5 to 45% 
by weight, more preferably 10 to 30% by weight. If the amount of the glass 
fiber is smaller than the lower limit, the reinforcing effect is low and 
the heat distortion temperature and rigidity of the molded article are 
reduced. If the amount of the glass fiber is larger than the upper limit, 
the flowability of the composition is reduced and the appearance of the 
molded article is degraded. If the amount of the polyolefin rubber exceeds 
the upper limit, the heat distortion temperature and rigidity of the 
molded article are reduced. 
Known additives may be added to the glass fiber-reinforced polypropylene 
composition of the present invention. For example, there may be added 
pigments, antioxidants, ultraviolet absorbers, flame retardants, 
antistatic agents, lubricants, nucleating agents, organic and inorganic 
fillers such as talc, calcium carbonate, mica, barium sulfate, (calcined) 
kaolin, silica, magnesium silicate, zeolite, carbon fiber, aromatic 
polyamide fiber, potassium titanate fiber, asbestos fiber, metal fiber, 
and boron fiber, and other thermoplastic resins such as nylon, polyester 
and polycarbonate, in so far as there is no adverse influence on the 
physical properties of the glass fiber-reinforced polypropylene 
composition. The amounts of these additives are appropriately determined 
based on the results of experiments. 
In the case where the glass fiber is a chopped strand, the glass 
fiber-reinforced polypropylene composition of the present invention can be 
prepared by kneading the above-mentioned components by an extruder, a 
Banbury mixer, an intensive mixer or the like. When the polyolefin rubber 
is used, the composition is preferably obtained by melt-kneading the 
graft-modified crystalline ethylene/propylene block copolymer (optionally 
together with the unmodified crystalline ethylene/propylene block 
copolymer) and the polyolefin rubber by a twin-screw extruder and kneading 
the obtained molten polymer mixture with the glass fiber by a single screw 
extruder. According to this method, breaking of the glass fiber is 
controlled and good results are obtained. 
The glass fiber-reinforced polypropylene composition of the present 
invention can be used in fields where a high rigidity and impact 
resistance are required, for example, for automobile parts, electric 
appliances, construction materials, and industrial parts.

The present invention will now be described in detail with reference to the 
following examples and comparative examples. In these examples, all of 
"parts" and "%" are by weight. 
In the examples, the ethylene content in the polymer was determined by the 
infrared spectrophotometry. With respect to injection-molded test pieces, 
the tensile strength was determined according to ASTM D-638, the flexural 
modulus was determined according to ASTM D-790, the heat distortion 
temperature was determined according to ASTM D-648 (at 18.6 kg/cm.sup.2), 
and the Izod impact strength (notched) was determined according to D-256 
(at 23.degree. C.). The appearance of the molded article was evaluated 
based on the gloss and surface roughness and on whether or not the glass 
fiber rose on the surface; the mark "A" indicates a good appearance, mark 
"B" indicates a slightly bad appearance, and mark "C" indicates a bad 
appearance. 
EXAMPLE 1 AND COMATIVE EXAMPLES 1 THROUGH 4 
In a tumbler, 100 parts of a crystalline ethylene/propylene block copolymer 
or crystalline propylene homopolymer shown in Table 1 was homogeneously 
mixed with 0.5 part of itaconic anhydride and 0.15 part of t-butyl 
peroxybenzoate, and the graft modification was carried out at a 
temperature of 200.degree. C. in a single screw extruder having a diameter 
of 65 mm for a residence time of 2 minutes, followed by pelletization, to 
obtain graft-modified polypropylene (the grafting ratio was 0.36% in 
Example 1). 
In a tumbler, 80 parts of this graft-modified polypropylene was mixed with 
20 parts of a glass fiber having a diameter of 10 .mu.m and a length of 6 
mm, treated with 0.1% of aminosilane, and by using a single screw extruder 
having a diameter of 65 mm, and the mixture was kneaded at a temperature 
of 220.degree. C. for a residence time of 2 minutes, followed by 
pelletization, to obtain a pellet of a glass fiber-reinforced 
polypropylene composition having a diameter of 3 mm and a length of 5 mm. 
A test piece obtained by injection-molding this pellet was evaluated. The 
obtained results are shown in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Comparative 
Comparative 
Comparative 
Comparative 
Example 1 
Example 1 
Example 2 
Example 
Example 
__________________________________________________________________________ 
4 
Crystalline 
MFR (g/10 min) 2 2 2 2 2 
polypro- 
Ethylene content (%) 
6.0 9.6 15.6 2.5 0 
pylene Intrinsic viscosity of portion soluble 
.sup. 4.0*.sup.1 
10.7 3.2 2.7 -- 
in p-xylene at normal temperature 
Ethylene content in portion insoluble in 
4.3 7.6 14.6 1.3 -- 
p-xylene at normal temperature (%) 
Physical 
Tensile strength (kg/cm.sup.2) 
640 600 580 650 880 
properties 
Flexural modulus (kg/cm.sup.2) 
33,000 30,000 28,000 33,000 38,000 
Heat distortion temperature (.degree.C.) 
141 136 135 143 153 
Izod impact strength (kg .multidot. cm/cm) 
15 12 9 8 9 
H.S.I.*.sup.2 (kg .multidot. cm) 
110 60 40 10 0 
Appearance of molded article 
A B C A A 
General evaluation A C C C C 
__________________________________________________________________________ 
Note 
.sup.1 The proportion of the portion soluble in pxylene at 
normaltemperature was 9%. 
.sup.2 The H.S.I. value was determined according to the Ube method 
(falling missile impact strength, which is a kind of drop weight impact 
strength). The value indicates the energy required for breaking the test 
piece when a missile having a top end diameter of 1 inch was caused to 
impact at a speed of 2.5 m/sec on the test piece, which was an 
injectionmolded disk having a thickness of 3 mm and a diameter of 100 mm. 
Note 
(1) The proportion of the portion soluble in p-xylene at normal temperature 
was 9%. 
(2) The H.S.I value was determined according to the Ube method (falling 
missile impact strength, which is a kind of drop weight impact strength). 
The value indicates the energy required for breaking the test piece when a 
missile having a top end diameter of 1 inch was caused to impact at a 
speed of 2.5 m/sec on the test piece, which was an injection-molded disk 
having a thickness of 3 mm and a diameter of 100 mm. 
EXAMPLE 2 
A glass fiber-reinforced polypropylene composition (pelletized) was 
obtained from 70 parts of the graft-modified polypropylene obtained in 
Example 1, 10 parts of graft-modified EPR (ethylene content=75%, Mooney 
viscosity ML.sub.1+4 (100.degree. C.)=80, maleic anhydride grafting 
ratio=1%) obtained by carrying out graft modification at 135.degree. C. 
for 4 hours with dicumyl peroxide as the catalyst in o-dichlorobenzene, 20 
parts of the same glass fiber as used in Example 1, 0.2 PHR (based on 
polypropylene) of Irganox 1010 (trademark, hindered phenol antioxidant) 
and 0.1 PHR (based on polypropylene) of BHT by using a continuous 
two-stage extruder. In the first stage of the extruder, mixing of the 
polymer components was carried out by using a twin screw extruder at 
200.degree. to 240.degree. C., and, in the second stage of the extuder, 
mixing of the polymer mixture with glass fiber was carried out by using a 
65 mm-diameter single screw extruder while a glass fiber is supplied from 
feed portion of the single screw extruder, at a mixing temperature of 
200.degree. to 280.degree. C. 
The composition was evaluated in the same manner as described in Example 1. 
It was found that the tensile strength was 590 kg/cm.sup.2, the flexural 
modulus was 30,000 kg/cm.sup.2, the heat distortion temperature was 
136.degree. C., the Izod impact strength was 25 kg.cm, the H.S.I value was 
200 kg.cm, the appearance of the molded article was good, and the general 
evaluation was good (A). 
EXAMPLES 3 AND 4 AND COMATIVE EXAMPLE 5 
A box-shaped molded article having a length of 500 mm, a width of 150 mm, 
and a height of 200 mm was prepared from the glass fiber-reinforced 
polypropylene (pellet) obtained in Example 1 (Example 3), Example 2 
(Example 4), or Comparative Example 1 (Comparative Example 5) by using an 
injection molding machine (Model UBE MAX 415-50 supplied by Ube 
Industries). 
With respect to each injection-molded article, 10 test pieces were tested 
in the following manner. Namely, a steel ball having a weight of 1 kg was 
allowed to fall from a height of 1 m onto the surface of the sample at 
-10.degree. C. The number of the samples where cracking or breaking 
occurred was checked. In Example 3, no sample was cracked or broken, and 
in Example 4 no sample was cracked or broken, but 10 samples were cracked 
or broken in Comparative Example 5. 
As is apparent from the foregoing description, a glass fiber-reinforced 
polypropylene composition having an excellent rigidity and impact strength 
can be obtained by a simple operation according to the present invention.