U.S. patent application number 08/837874 was filed with the patent office on 2001-07-19 for polyolefin-based resin composition and automotive molded plastic made from same.
Invention is credited to ADACHI, MINORU, HIRATA, TOMIO, ICHIKAWA, SATORU, KAMAE, HIROSUKE, KAWAI, AKIRA, MATSUYAMA, KAZUO, OHASHI, TAMIHIRO, OHNISHI, KAZUSHIGE, TERADA, MASAHIRO, YAMAMOTO, KAZUYUKI.
Application Number | 20010008915 08/837874 |
Document ID | / |
Family ID | 14449081 |
Filed Date | 2001-07-19 |
United States Patent
Application |
20010008915 |
Kind Code |
A1 |
HIRATA, TOMIO ; et
al. |
July 19, 2001 |
POLYOLEFIN-BASED RESIN COMPOSITION AND AUTOMOTIVE MOLDED PLASTIC
MADE FROM SAME
Abstract
The invention relates to a polyolefin-based resin composition
that is in an amount of 100 wt % in total. This composition
includes (a) 60-66 wt % of a crystalline propylene-ethylene block
copolymer, (b) 12-20 wt % of an ethylene-propylene copolymer
rubber, and (c) 18-25 wt % of an inorganic filler. The block
copolymer contains a first segment of a homopolymer of propylene
and a second segment of a copolymer of propylene and ethylene, and
has an isotactic pentad tacticity of at least 0.96. The ratio of
the weight average molecular weight of the block copolymer to the
number average molecular weight thereof is not greater than 6. The
copolymer rubber contains therein 50-60 wt % of ethylene, and has a
Mooney viscosity of from 45 to 55 at 125.degree. C. The inorganic
filler is one selected from the group consisting of a talc, a first
combination of the talc and a glass fiber, and a second combination
of the talc and a whisker. The talc has an average particle
diameter of not greater than 2 .mu.m. The glass fiber has an
average fiber length of from 5 to 10 mm and an average diameter of
from 15 to 20 .mu.m. The whisker has an average fiber length of
from 15 to 25 .mu.m and an average diameter of from 0.5 to 1 .mu.m.
A molded plastic article made from the resin composition is
substantially improved in scratch resistance.
Inventors: |
HIRATA, TOMIO; (EATON,
OH) ; ADACHI, MINORU; (CHIBA, JP) ; OHASHI,
TAMIHIRO; (CHIBA, JP) ; MATSUYAMA, KAZUO;
(SHIZUOKA, JP) ; YAMAMOTO, KAZUYUKI; (SHIZUOKO,
JP) ; OHNISHI, KAZUSHIGE; (SHIZUOKA, JP) ;
ICHIKAWA, SATORU; (KANAGAWA, JP) ; TERADA,
MASAHIRO; (KANAGAWA, JP) ; KAMAE, HIROSUKE;
(KANAGAWA, JP) ; KAWAI, AKIRA; (KANAGAWA,
JP) |
Correspondence
Address: |
FOLEY & LARDNER
3000 K STREET NW SUITE 500
P O BOX 25696
WASHINGTON
DC
200078696
|
Family ID: |
14449081 |
Appl. No.: |
08/837874 |
Filed: |
April 25, 1997 |
Current U.S.
Class: |
524/423 ;
524/451 |
Current CPC
Class: |
C08L 53/00 20130101;
C08L 2666/04 20130101; C08L 53/00 20130101 |
Class at
Publication: |
524/423 ;
524/451 |
International
Class: |
C08K 003/30 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 1996 |
JP |
8-107043 |
Claims
What is claimed is:
1. A polyolefin-based resin composition that is in an amount of 100
wt % in total, said composition comprising: (a) 60-66 wt % of a
crystalline propylene-ethylene block copolymer, said block
copolymer comprising a first segment of a homopolymer of propylene
and a second segment of a copolymer of propylene and ethylene, said
block copolymer having an isotactic pentad tacticity of at least
0.96, a ratio of a weight average molecular weight of said block
copolymer to a number average molecular weight of said block
copolymer being not greater than 6; (b) 12-20 wt % of an
ethylene-propylene copolymer rubber containing therein 50-60 wt %
of ethylene, said rubber having a Mooney viscosity of from 45 to 55
at 125.degree. C.; (c) 18-25 wt % of an inorganic filler that is
one selected from the group consisting of a talc, a first
combination of said talc and a glass fiber, and a second
combination of said talc and a whisker, said talc having an average
particle diameter of not greater than 2 .mu.m, said glass fiber
having an average fiber length of from 5 to 10 mm and an average
diameter of from 15 to 20 .mu.m, and said whisker having an average
fiber length of from 15 to 25 .mu.m and an average diameter of from
0.5 to 1 .mu.m.
2. A resin composition according to claim 1, wherein said inorganic
filler is said talc.
3. A resin composition according to claim 1, wherein said inorganic
filler is said first combination, and a weight ratio of said talc
to said glass fiber is from 1:1 to 3:1.
4. A resin composition according to claim 1, wherein said inorganic
filler is said second combination, and a weight ratio of said talc
to said whisker is from 1:1 to 3:1.
5. A resin composition according to claim 1, wherein said
ethylene-propylene copolymer rubber has a Mooney viscosity of from
48 to 52 at 125.degree. C.
6. A resin composition according to claim 1, wherein said
ethylene-propylene copolymer rubber contains 52-56 wt % of
ethylene.
7. A resin composition according to claim 1, wherein said whisker
is made of basic magnesium sulfate.
8. A molded plastic article made from a polyolefin-based resin
composition according to claim 1.
9. A molded plastic article according to claim 8, wherein said
molded plastic article has a melt flow rate of at least 10 g/10
min, a specific gravity of from 1.00 to 1.09, a flexural elastic
modulus of at least 1,960 MPa, and an Izod impact value of at least
9.8 kJ/m.sup.2 at 0.degree. C.
10. A molded plastic article according to claim 8, wherein said
molded plastic article is an automotive garnish member for covering
a part of an automobile.
11. A molded plastic article according to claim 10, wherein said
part of said automobile is one of an automotive pillar and an
automotive door.
12. A molded plastic article according to claim 8, wherein said
molded plastic article is an automotive instrument panel.
13. A molded plastic article according to claim 11, wherein said
automotive pillar is one of front, center and rear pillars of a
vehicle body of said automobile.
14. A molded plastic article according to claim 11, wherein said
automotive garnish member has a major portion and a plurality of
reinforcing ribs that extend from said major portion toward said
pillar such that said reinforcing ribs are positioned between said
major portion and said pillar, and wherein said reinforcing ribs
are arranged such that a clearance between said reinforcing ribs
and said pillar is at least 0.5 mm.
15. A molded plastic article according to claim 14, wherein each of
said reinforcing ribs has a thickness of from 0.8 to 1.7 mm, and
wherein said reinforcing ribs are arranged such that a distance
between two of said reinforcing ribs, which two are adjacent to
each other, is from 5 to 50 mm.
16. A molded plastic article according to claim 8, wherein said
molded plastic article has a Rockwell hardness of at least 50 under
R scale.
17. A molded plastic article according to claim 15, wherein said
distance is from 15 to 30 mm.
18. A molded plastic article according to claim 8, wherein said
molded plastic article is prepared by a method comprising steps of:
(a) stirring said resin composition; (b) melting said resin
composition obtained by the step (a) at a temperature of from 150
to 300.degree. C., thereby to prepare a melt; (c) pelletizing said
melt into pellets; and (d) molding said pellets into said molded
plastic article.
19. A molded plastic article according to claim 18, wherein said
temperature of the step (b) is from 180 to 250.degree. C.
20. A molded plastic article according to claim 18, wherein the
step (d) is conducted by one of injection molding, gas injection
molding, and injection compression molding.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to polyolefin-based resin
compositions reinforced with filler and to automotive molded
plastics made from the resin compositions, such as automotive
garnish or trim members, which are disposed in the interior (i.e.,
passenger compartment) of an automobile, for covering pillars and
side roof rails of the automobile. With the use of such plastics,
the automobile interior is improved in appearance.
[0002] Conventional automotive molded plastics by themselves which
are made from conventional polyolefin-based resin compositions are
not sufficient in scratch resistance. Some of these plastics are
improved in scratch resistance by increasing hardness thereof. They
are, however, still not sufficient in scratch resistance. In other
words, they have a sufficient resistance to weak scratching caused,
for example, by rubbing of cloth, by fingernails, and by other
members, but still have an insufficient resistance to strong
scratching caused by a sharply cornered object. Thus, conventional
automotive molded plastics used, for example, as pillar garnish
member (i.e., garnish for covering automotive pillars) may have
scratches by a strong impact, for example, of the tongue portion of
an automotive seat belt. In FIG. 3, there is shown an automotive
pillar garnish member 10 for covering an automotive front pillar
12. This pillar garnish member 10 is made from a thermoplastic
resin and has conventional reinforcing ribs 14. The automotive
pillar garnish member 10 is required to have characteristics of
decoration, stoutness, high rigidity, high quality, and the like.
In particular, it is required to have high rigidity at the time of
its installation in automobile and at high temperature and high
moldability. A thermoplastic resin reinforced with filler (e.g.,
talc) has good characteristics such as high moldability. An
automotive pillar garnish member made from this resin is, however,
still insufficient in scratch resistance.
[0003] Some of conventional molded plastics, such as plastics used
as automotive bumpers, are prepared by adding elastomers to the
other components thereof. Such plastics are, however, insufficient
in elastic modulus for the use, for example, as pillar garnish
member.
SUMMARY OF THE INVENTION
[0004] It is therefore an object of the present invention to
provide a polyolefin-based resin composition that is capable of
providing a molded plastic article which is substantially improved
in scratch resistance, while the molded plastic has good
characteristics, such as high rigidity, which are comparable to
those of conventional pillar garnish members.
[0005] It is another object of the present invention to provide
such molded plastic article.
[0006] According to the present invention, there is provided a
polyolefin-based resin composition that is in an amount of 100 wt %
in total, said composition comprising:
[0007] (a) 60-66 wt % of a crystalline propylene-ethylene block
copolymer, said block copolymer comprising a first segment of a
homopolymer of propylene and a second segment of a copolymer of
propylene and ethylene, said block copolymer having an isotactic
pentad tacticity of at least 0.96, a ratio of a weight average
molecular weight of said block copolymer to a number average
molecular weight of said block copolymer being not greater than
6;
[0008] (b) 12-20 wt % of an ethylene-propylene copolymer rubber
containing therein 50-60 wt % of ethylene, said rubber having a
Mooney viscosity of from 45 to 55 at 125.degree. C.;
[0009] (c) 18-25 wt % of an inorganic filler that is one selected
from the group consisting of a talc, a first combination of said
talc and a glass fiber, and a second combination of said talc and a
whisker, said talc having an average particle diameter of not
greater than 2 .mu.m, said glass fiber having an average fiber
length of from 5 to 10 mm and an average diameter of from 15 to 20
.mu.m, and said whisker having an average fiber length of from 15
to 25 .mu.m and an average diameter of from 0.5 to 1 .mu.m.
[0010] According to the present invention, there is further
provided a molded plastic article made from the above
polyolefin-based resin composition.
[0011] A polyolefin-based resin composition according to the
present invention is capable of producing a molded plastic article
which is particularly improved in scratch resistance (i.e.,
resistance to scratching). In other words, a molded plastic article
according to the present invention hardly receives substantial
damage (e.g., scratches, cuts, marks, and the like) thereon, even
if a sharply cornered object (e.g., the tongue portion of an
automotive seat belt) hits strongly against the molded plastic
article. In the invention, the molded plastic article is provided
with good elasticity by the incorporation of the above particular
amount of the special copolymer rubber. With this, the molded
plastic article is substantially improved in scratch resistance.
Furthermore, the inventors have unexpectedly found that Izod impact
value of a molded plastic article is an effective parameter for
evaluating scratch resistance thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a sectional view showing a first automotive pillar
garnish member that covers an automotive front pillar and has
reinforcing ribs according to a first embodiment of the present
invention;
[0013] FIG. 2 is a view similar to FIG. 1, but showing a second
automotive pillar garnish member having reinforcing ribs according
to a second embodiment of the present invention; and
[0014] FIG. 3 is a view similar to FIG. 1, but showing an
automotive pillar garnish member having conventional reinforcing
ribs.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] In FIG. 1, there is shown an exemplary first automotive
pillar garnish member 20 for covering an automotive front pillar 22
(windshield pillar) disposed between a front windshield and a door
glass plate. The front pillar 22 has inner and outer portions 22a
and 22b that are attached to each other at their flanges by spot
welding or the like. The pillar garnish member 20 is shaped such
that the front pillar 22 is fully covered or concealed thereby.
According to need for decoration, it is optional to provide the
surface of the pillar garnish member 20 with an uneven fine pattern
thereon or to cover the same with an outer skin layer that is a
synthetic resin or fabric sheet having thereon fibers or the like.
A rubber sealing member 24 is provided at one end portion of the
pillar garnish member 20 in order to conceal clearance between the
pillar garnish member 20 and the front pillar 22 and a welded
portion of the front pillar 22. It is preferable that the first
automotive pillar garnish member 20 has reinforcing ribs 26
according to a first embodiment of the present invention, as shown
in FIG. 1. There is provided in FIG. 2 a second automotive pillar
garnish member 30 having reinforcing ribs 32 according to a second
embodiment of the present invention. These reinforcing ribs 26 and
32 have sectional shapes that are different from that of the
conventional ones 14 shown in FIG. 3. The reinforcing ribs 26 or 32
and a major portion 28 or 34 of the pillar garnish member 20 or 30
constitute a one-piece body. The pillar garnish member 20 or 30 is
provided with the reinforcing ribs 26 or 32 for the purpose of
suppressing deformation (expansion of a mouth portion) of the
pillar garnish member 20 or 30 and of improving the pillar garnish
member 20 or 30 in rigidity such as flexural rigidity, torsional
rigidity and heat rigidity.
[0016] In the invention, when the first combination of the talc and
the glass fiber or the second combination of the talc and the
whisker is used as the inorganic filler, it is preferable that the
weight ratio of the talc to the glass fiber or the whisker is in a
range of from 1:1 to 3:1. If it is less than 1:1 or greater than
3:1, a molded plastic article according to the present invention
may become improved in rigidity. With this, however, the molded
plastic article may become inferior in scratch resistance. In other
words, the molded plastic article may have scratches thereon, when
the tongue portion of an automotive seat belt hits strongly against
this article.
[0017] In the invention, it is preferable that an automotive
garnish member according to the present invention has on the back
side thereof a plurality of reinforcing ribs having sectional
shapes, for example, as shown in FIGS. 1 and 2. It is preferable
that each reinforcing rib has a thickness of from 0.8 to 1.7 mm. If
it is less than 0.8 mm, the resin composition may become inferior
in moldability. In other words, when an automotive garnish member
is formed by injection molding, the resin composition may not be
introduced into the whole of the injection mold. With this, the
reinforcing ribs may not have their predetermined proper shapes. If
it is greater than 1.7 mm, the automotive garnish member may have
sink to lower its value as a commercial product. It is preferable
that each two of the reinforcing ribs, which are adjacent to each
other, has a clearance therebetween of from 5 to 50 mm. In other
words, this clearance is preferably up to 50 mm, more preferably up
to 30 mm, for the purpose of having sufficient rigidity at the time
of the installation of the garnish member and at high temperature.
Furthermore, the clearance is preferably at least 5 mm, more
preferably at least 15 mm, in view of the mold strength and
releasibility from mold. If it is less than 5 mm, a portion of the
mold for forming the reinforcing ribs may become inferior in
strength. If it is greater than 50 mm, the automotive garnish
member may become inferior in rigidity at the time of its
installation and at high temperature. Thus, its value as a
commercial product may be lowered.
[0018] In the invention, if the crystalline propylene-ethylene
block copolymer has an isotactic pentad tacticity (I.sub.5) less
than 0.96 or a ratio of its weight average molecular weight (Mw) to
its number average molecular weight (Mn) of greater than 6, the
molded plastic article used as an automotive garnish member becomes
inferior in rigidity and heat resistance. This ratio (Mw/Mn) is
also called Q value. The isotactic pentad tacticity (I.sub.5) is a
parameter for determining the degree of the intramolecular
stereoregularity of the block copolymer and can be determined, for
example, by measuring the melt flow rate of the block copolymer.
When two methyl groups of adjacent propylene monomers in the
propylene chain of a polypropylene are on the same side of the main
chain of the polypropylene, these methyl groups are designated by
"meso" (m). In contrast, when those are on the opposite sides
thereof, they are designated by "racemic" (r). Thus, when the
consecutive five (pentad) propylene monomers are on the same side
thereof, these consecutive five propylene monomers are designated
by "mmmm". The ratio of the total number of five consecutive
propylene monomers designated by "mmmm" in a polypropylene to the
total number of all five consecutive propylene monomers designated
by mmmm, mmmr, rmmr, mmrr, mmrm, rmrr, mrmr, rrrr, mrrr and mrrm in
the polypropylene is referred to as the isotactic pentad tacticity
(I.sub.5).
[0019] In the invention, the ethylene-propylene copolymer rubber
contains therein 50-60 wt % (preferably 52-56 wt %) of ethylene and
has a Mooney viscosity (ML.sub.1+4) of from 45 to 55, preferably
from 48 to 52, at 125.degree. C. If the ethylene content of the
rubber and its Mooney viscosity are respectively out of ranges of
50-60 wt % and 45-55, the molded plastic article used as an
automotive garnish member becomes inferior in resistance to
scratches caused by the impact of the tongue portion of an
automotive seat belt. Furthermore, the rubber becomes insufficient
in dispersibility in the resin composition.
[0020] In the invention, the inorganic filler is used for the
purpose of improving the molded plastic article in rigidity. The
inorganic filler is one selected from the group consisting of the
talc, the first combination of the talc and the glass fiber, and
the second combination of the talc and the whisker. The talc has an
average particle diameter within a range of not greater than 2
.mu.m. The glass fiber has an average fiber length within a range
of from 5 to 10 mm and an average diameter within a range of from
15 to 20 .mu.m. The whisker has an average fiber length within a
range of from 15 to 25 .mu.m and an average diameter within a range
of from 0.5 to 1 .mu.m. If the average diameter of the talc is out
of the above range, this talc is not capable of achieving the
improvement of the molded plastic article in rigidity and in
resistance to scratches caused by the impact of the tongue portion
of an automotive seat belt. If each of the average fiber length and
the average diameter of the glass fiber is out of the above range,
this glass fiber is not capable of achieving the above improvement,
either. If each of the average fiber length and the average
diameter of the whisker is out of the above range, this whisker is
not capable of achieving the above improvement, either.
[0021] As stated above, a polyolefin-based resin composition
according to the present invention comprises three components of
(a) 60-66 wt % of the crystalline propylene-ethylene block
copolymer, (b) 12-20 wt % of the ethylene-propylene copolymer
rubber, and (c) 18-25 wt % of the inorganic filler. If each
component is in an amount out of the above range, the molded
plastic article becomes insufficient in rigidity and in resistance
to scratches caused by the impact of the tongue portion of an
automotive seat belt.
[0022] In the invention, it is optional to add an additive to the
resin composition. This additive is at least one selected from the
group consisting of antioxidant, antistatic agent, coloring agent
(pigment), nucleus forming agent, slipping agent, mold release
agent, fire retardant, ultraviolet absorbing agent, light
stabilizer, plasticizer, and radical generator.
[0023] In the invention, the components and the optional additive
of the resin composition may be in the form of powder or granule.
The resin composition can be prepared, for example, by mixing the
components and the optional additive, using ribbon blender, tumble
mixer, Henschel mixer, super mixer, or the like, then by kneading
the resultant mixture at a temperature of from 150 to 300.degree.
C., preferably from 180 to 250.degree. C., using rollers, Banbury
mixer, labo plastomill, single- or twin-screw extruder, or the
like, and then by pelletizing the kneaded mixture. The resultant
resin composition can be molded into various shapes, by injection
molding, injection compression molding, vacuum molding, or
extrusion (e.g., extrusion blow molding). Of these molding methods,
it is preferable to use injection molding, gas injection molding,
or injection compression molding, in the present invention.
[0024] When a molded plastic article according to the present
invention is used as an automotive garnish (trim) member, it is
preferable that the molded plastic article has a melt flow rate of
at least 10 g/10 min, a specific gravity of from 1.00 to 1.09, a
flexural elastic modulus of at least 1,960 MPa, a Rockwell hardness
(R scale) of at least 50, and an Izod impact value of at least 9.8
kJ/m.sup.2 at 0.degree. C., under the following measurement
conditions. In the invention, the melt flow rate of the molded
plastic article is measured at 230.degree. C. under a load of 21.18
N, in accordance with Japanese Industrial Standard (JIS) K 7210. If
the melt flow rate is less than 10 g/10 min, the molded plastic
article may become inferior in external appearance. In the
invention, the flexural elastic modulus is measured at 23.degree.
C. in accordance with JIS K 7203. If the flexural elastic modulus
is lower than 1,960 MPa, the molded plastic article may become
insufficient in rigidity at the time of installation and at high
temperature. With this, it may become insufficient in stoutness and
may become large in deformation at high temperature. In the
invention, the Rockwell hardness is measured in accordance with JIS
K 6758, under R scale. If the Rockwell hardness is lower than 50,
the molded plastic article may become inferior in scratch
resistance. Thus, it may have scratches thereon, when it is
released from a mold, or when it is handled in a factory. In the
invention, the Izod impact value is measured at 0.degree. C. and
23.degree. C., by making a notch on the molded plastic article, in
accordance with JIS K 7110. If the Izod impact value is lower than
9.8 kJ/m.sup.2, the molded plastic article may have scratches
thereon by the impact of a sharply cornered object such as the
tongue portion of an automotive seat belt.
[0025] In the invention, it is preferable that the reinforcing ribs
are formed such that clearance between the reinforcing ribs and the
automotive pillar is at least 0.5 mm. With this, there can be
suppressed noise generated by closely positioning the reinforcing
ribs relative to the pillar. Furthermore, this clearance allows a
certain production error of the pillar in dimension.
[0026] It is optional to use a molded plastic article of the
present invention as a core of an automotive trim (garnish) member
having thereon an outer skin member (e.g., a synthetic resin sheet
or a fabric sheet). This outer skin member is optionally formed
thereon with fibers and the like. As mentioned hereinabove, a resin
composition of the present invention is superior in moldability,
and a molded plastic article made from this resin composition is
superior in rigidity and scratch resistance. Therefore, the molded
plastic article can be used, for example, for various automotive
parts such as pillar trim member, door trim member, and instrument
panel. The molded plastic article used as an automotive trim member
may effectively absorb the energy of the impact of an automotive
passenger on the article.
[0027] The following nonlimitative examples are illustrative of the
present invention.
EXAMPLE 1
[0028] At first, as shown in Table, 64 wt % of a first crystalline
propylene-ethylene block copolymer (PP-1), 13 wt % of an
ethylene-propylene copolymer rubber (EPR), and 23 wt % of a talc
(filler) were mixed together for 2 min. using Henschel mixer. Then,
the resultant mixture was kneaded and extruded by using a
single-screw extruder, NVC-50 of Nakatani Kikai Co., and then was
pelletized. The PP-1 had a first segment of a homopolymer of
propylene and a second segment of a copolymer of propylene and
ethylene. The PP-1 had a melt flow rate of 20 g/10 min. at
230.degree. C. under a load of 21.18 N, an isotactic pentad
tacticity of 0.980, a ratio of its weight average molecular weight
(Mw) to its number average molecular weight (Mn) of 5.5. The EPR
contained 54% of ethylene and had a Mooney viscosity (ML.sub.1+4)
of 50 at 125.degree. C. The talc had an average particle diameter
of 1.7 .mu.m.
[0029] The resultant pellets were subjected to the melt flow rate
test. In this test, the melt flow rate was measured at 230.degree.
C. under a load of 21.18 N, in accordance with JIS K 7210, as
stated above. The result of this test is shown in Table.
[0030] A test piece of the molded plastic article was prepared from
the pellets by injection molding at a molding temperature of
220.degree. C. and at a mold temperature of 50.degree. C. This test
piece was subjected at 23.degree. C. to a tensile test according to
JIS K 7113, a flexural elastic modulus (three-point flexural
elastic modulus) test according to JIS K 7203, an Izod impact
strength test according to JIS K 7110, a heat distortion
temperature test according to JIS K 7203 under a load of 0.45 MPa,
and a Rockwell hardness test (R scale) according to JIS K 7202. The
Izod impact strength test was conducted at temperatures of
23.degree. C. and 0.degree. C., by making a notch on the test
piece. The results of these tests are shown in Table.
[0031] A pillar garnish member was prepared from the pellets, by
using an injection molding machine of a mold clamping force of 350
ton, at a molding temperature of 220.degree. C. In this
preparation, the surface of the pillar garnish member was provided
with an uneven fine pattern. The pillar garnish member 20 was
formed with reinforcing ribs 26 having a shape shown in FIG. 1 and
had a major portion 28 having a thickness of 2.5 mm. The pillar
garnish member was subjected to an external appearance test. In
this test, the surface of the pillar garnish member was observed
with the naked eye to check whether or not sink exists thereon. In
Table, "A" means that sink did not exist on the surface of the
pillar garnish member, and "B" means that it existed thereon. The
pillar garnish member was further subjected to a scratch test. In
this test, the metal tongue portion of an automotive seat belt was
allowed to fall on the pillar garnish member from a height of 1.5
m. After the test, the surface of the pillar garnish member was
observed with the naked eye to check whether or not scratches exist
thereon. In Table, "A" means that scratches did not exist thereon,
and "B" means that they existed thereon. The pillar garnish was
further subjected to a heat cycle test. In this test, the pillar
garnish was installed in an automobile body, and then was subjected
to a heat cycle of from -40.degree. C. to 90.degree. C. four times.
After that, the pillar garnish member was observed to check whether
or not it has the original shape and thus can mate properly with
another member. In Table, "A" means that it had the original shape
and thus could mate properly with another member, and "B" means
that it did not have that and could not mate properly with
that.
EXAMPLES 2-4
[0032] In each of these examples, a pillar garnish member was
prepared by using the pellets of Example 1, in the same manner as
that of Example 1, except in that selective changes were made in
the thickness of the reinforcing ribs of the pillar garnish member
and in the clearance between each two of the reinforcing ribs
thereof, as shown in Table. Then, the evaluation tests of Example 1
were conducted on each pillar garnish member.
EXAMPLE 5
[0033] In this example, a pillar garnish member was prepared by
using the pellets of Example 1, in the same manner as that of
Example 1, except in that the thickness of the reinforcing ribs of
the pillar garnish member was changed, as shown in Table, and that
the shape of the reinforcing ribs was changed to that shown in FIG.
2. Then, the evaluation tests of Example 1 were conducted on the
pillar garnish member.
EXAMPLES 6-9
[0034] In each of these examples, Example 1 was repeated except in
that selective changes were made in the kinds and the amounts of
the components of the resin composition, that the thickness of the
reinforcing ribs of the pillar garnish member was changed, as shown
in Table, and that the shape of the reinforcing ribs was changed to
that shown in FIG. 2. In each of Examples 7-9, there was used, in
place of PP-1, another crystalline propylene-ethylene copolymer
(PP-2) that had the same characteristics as those of PP-1, except
that the melt flow rate at 230.degree. C. under a load of 21.18 N
was 30 g/10 min. In Example 8, there was used, in addition to the
talc, 5 wt % of whiskers that were made of basic magnesium sulfate
and had an average fiber length of 20 .mu.m and an average diameter
of 0.7 .mu.m. In Example 9, there was used, in addition to the
talc, glass fibers having an average fiber length of 6 mm and an
average diameter of 17 .mu.m.
COMPARATIVE EXAMPLE 1
[0035] In this comparative example, Example 1 was repeated except
in that selective changes were made in the kinds and the amounts of
the components of the resin composition, that the thickness of the
reinforcing ribs of the pillar garnish member was changed, as shown
in Table, and that the shape of the reinforcing ribs was changed to
that shown in FIG. 2. In fact, there was used, in place of PP-1,
still another crystalline propylene-ethylene copolymer (PP-3) that
had the same characteristics as those of PP-1, except that the
isotactic pentad tacticity was 0.978 and the ratio of Mw/Mn (Q
value) was 10.0.
COMPARATIVE EXAMPLE 2
[0036] In this comparative example, a pillar garnish member was
prepared by using the pellets of Example 1, in the same manner as
that of Example 1, except in that the thickness of the reinforcing
ribs of the pillar garnish member was changed, as shown in Table,
and that the shape of the reinforcing ribs was changed to that
shown in FIG. 3. Then, the evaluation tests of Example 1 were
conducted on each pillar garnish member.
COMPARATIVE EXAMPLES 3-4
[0037] In each of these examples, a pillar garnish member was
prepared by using the pellets of Example 1, in the same manner as
that of Example 1, except in that selective changes were made in
the thickness of the reinforcing ribs of the pillar garnish member
and in the clearance between each two of the reinforcing ribs
thereof, as shown in Table, and that the shape of the reinforcing
ribs was changed to that shown in FIG. 2.
1TABLE Ex. Ex. Ex. 1 Ex. 2 3 4 Ex. 5 Ex. 6 Ex. 7 Reinforcing Ribs
1.0 1.0 1.5 1.7 1.5 1.5 1.5 Thickness (mm) Reinforcing Ribs 20 50
20 20 20 20 20 Clearance (mm) Resin Composition (wt %) PP-1 64 61
PP-2 61 PP-3 EPR 13 15 15 Talc 23 24 24 Glass Fibers Whiskers Test
Sample Characteristics Melt Flow 14 10 18 Rate (g/10 min) Tensile
Strength 21.6 19.1 19.1 (MPa) Elongation in 90 80 50 Tensile Test
(%) Flexural Elastic 2452 2069 2079 Modulus (MPa) Flexural 30.9 26
26 Strength (MPa) Izod Impact >40 >40 >40 Value at
23.degree. C. (kJ/m.sup.2) Izod Impact 9.8 >40 >40 Value at
0.degree. C. (kJ/m.sup.2) Heat Distortion 135 125 125 Temp.
(.degree. C.) Rockwell 70 53 53 Hardness (R Scale) Pillar Garnish
Member Characteristics Ext. Appearance A A A A A A A Test Scratch
Test A A A A A A A Heat Cycle Test A A A A A A A Com. Com. Com.
Com. Ex. 8 Ex. 9 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Reinforcing Ribs 1.5 1.5
1.5 1.5 2.0 1.5 Thickness (mm) Reinforcing Ribs 20 20 20 20 20 80
Clearance (mm) Resin Composition (wt %) PP-1 PP-2 65 66 PP-3 86 EPR
15 15 Talc 15 12 14 Glass Fibers 7 Whiskers 5 Test Sample
Characteristics Melt Flow 20 10 21 Rate (g/10 min) Tensile Strength
18.1 36.8 28.9 (MPa) Elongation in 60 10 26 Tensile Test (%)
Flexural Elastic 2069 2040 2500 Modulus (MPa) Flexural 24.9 44.1
42.7 Strength (MPa) Izod Impact >40 >40 5.2 Value at
23.degree. C. (kJ/m.sup.2) Izod Impact >40 >40 4.2 Value at
0.degree. C. (kJ/m.sup.2) Heat Distortion 120 155 135 Temp.
(.degree. C.) Rockwell 52 76 93 Hardness (R Scale) Pillar Garnish
Member Characteristics Ext. Appearance A A A A B A Test Scratch
Test A A B A A A Heat Cycle Test A A A B A B
[0038] The entire disclosure of Japanese Patent Application No.
8-107043 filed on Apr. 26, 1996, including specification, claims,
drawings and summary, is incorporated herein by reference in its
entirety.
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