Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-07-27
2003-06-17
Short, Patricia A. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
active
06579935
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polyester resin composition in which a graft-modified ethylene/&agr;-olefin random copolymer is compounded.
BACKGROUND OF THE INVENTION
Thermoplastic polyester resins, such as polyethylene terephthalate, polybutylene terephthalate and so on, have been used as engineering plastics due to their superior performances in, for example, mechanical strength, stiffness, heat resistance, resistance to chemicals and resistance to oils, and have found applications for, for example, machine parts, parts for electric devices and appliances and parts for automobile.
While such thermoplastic polyester ersins as polyethylene terephthalate etc. are certainly superior in the properties as given above, they are inferior in the impact resistance as compared with polycarbonate resin and so on and, thus, may sometimes be limited in the field of application thereof. For this reason, attempts have been made to improve the impact resistance.
For example, Japanese Patent Publication Sho 46-5225 B discloses a polyester resin composition in which a polyester is blended with ethylene/propylene rubber, polyisobutene or polybutene etc.
However, this composition exhibits an insufficient effect of improvement in the impact resistnce, since the polyester is inferior in the compatibility with the ethylene/propylene rubber etc.
In Japanease Patent Publications Sho 57-54058 B and Sho 57-59261 B, a polyester resin composition is disclosed, in which a graft-modified ethylenic polymer having a degree of crystallinity not higher than 75% obtained by grafting an &agr;, &bgr;-unsaturated carboxylic acid or a derivative thereof onto an ethylenic polymer is melt-blended.
However, the above polyester resin composition also exhibits insufficient effect of improvement in the impact resistance together with decreased fracture toughness. While the impact resistance may be increased by increasing the proportion of the graft-modified ethylenic polymer, this causes decrease in the stiffness.
Japanese Patent Publication Sho 59-28223 B (corresponding to U.S. Pat. No. 4,172,859) discloses a poly-ester resin composition compounded with a graft-modified ethylene/&agr;-olefin random copolymer obtained by grafting an &agr;, &bgr;-unsaturated carboxylic acid derivative or an unsaturated epoxide etc. onto an an ethylene/&agr;-olefin random copolymer. Japanese Patent Kokai Sho 58-17148 A (corresponding to U.S. Pat. No. 4,461,871) discloses a polyester resin composition obtained by blending a copolymer of ethylene with a copolymer of an &agr;-olefin and a glycidyl ester of an &agr;, &bgr;-unsaturated acid. Japanese Patent Kokai Sho 60-28446 A discloses a polyester resin composition obtained by blending a polyepoxy compound with a graft-modified ethylene/&agr;-olefin copolymer obtained by grafting an unsaturated carboxylic acid or anhydride thereof onto the copolymer.
These polyester resin compositions exhibit also insufficient improvement in the impact resistance and an attempt to increase the impact resistance by increasing the proportion of additive may result in a decrease in the stiffness.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a polyester resin composition which is superior in the impact resistance, especially in the impact resistance at low temperatures (Low temperature impact resistance) together with excellencies in the stiffness and in the fracture toughness (tensile toughness).
The present invention resides in the polyester resin composition as given below:
(1) A polyester resin composition, comprising
(A) a polyester resin and
(B) a graft-modified ethylene/&agr;-olefin random copolymer in which an unsaturated carboxylic acid or a derivative thereof (B-2) is grafted onto an ethylene/&agr;-olefin random copolymer (B-1) comprising a structural unit of ethylene and a structural unit of an &agr;-olefin of 6-20 carbon atoms,
in a proportion of 5-200 parts by weight of (B) per 100 parts by weight of (A), wherein the grafted amount of the unsaturated carboxylic acid or the derivative thereof (B-2) is 0.01-10 % by weight and wherein the ethylene/&agr;-olefin random copolymer (B-1) has, before the graft-modification, the features
(a) that the content of the structural unit of the &agr;-olefin of 6-20 carbon atoms is 6-25 mole % and
(b) that the melt flow rate (ASTM D 1238, 190° C., 2.16 kg load) is 0.1-50 g/10 min.
(2) The polyester resin composition as defined in the above (1), wherein the ethylene/&agr;-olefin random copolymer (B-1) before the graft-modification is that obtained by subjecting ethylene and the &agr;-olefin of 6-20 carbon atoms to a random copolymerization in the presence of a catalyst based on metallocene.
(3) The polyester resin composition as defined in the above (1) or (2), wherein the ethylene/&agr;-olefin random copolymer (B-1) is a linear ethylene/&agr;-olefin random copolymer which has, before the graft modification, the features
(c) that it has a glass transition temperature (Tg) of not higher than minus 50° C.,
(d) that it has a degree of crystallinity determined by X-ray diffraction method.of lower than 30%,
(e) that it has a molecular weight distribution (Mw/Mn) determined by gel permeation chromatography (GPC) of not higher than 3,
(f) that it has a B-value calculated by the equation (I)
B=P
OE
/(2
P
O
·P
E
) (I)
of 1-1.4, wherein P
E
and P
O
represent each a mole fraction of the ethylene structural unit and that of the structural unit of &agr;-olefin in the ethylene/&agr;-olefin random copolymer (B-1) before the modification, respectively, and P
OE
denotes a proportion of number of the ethylene/&agr;-olefin alternating chain units relative to the total number of dyads, determined from
13
C-NMR spectrum, and
(g) that the ratio of the intrinsic viscosity [&eegr;] of the ethylene/&agr;-olefin random copolymer (B-1) versus the intrinsic viscosity [&eegr;]
blank
of an ethylene/propylene linear random copolymer, both determined in decalin at 135° C., i.e. g&eegr;*=[&eegr;]/[&eegr;]
blank
, is in excess of 0.95, wherein the said ethylene/propylene linear random copolymer has a content of the structural unit of ethylene of 70 mole % and a weight-average molecular weight (Mw) determined by light scattering method identical to that of the ethylene/&agr;-olefin random copolymer (B-1).
(4) The polyester resin composition as defined in the above (3), wherein the linear ethylene/&agr;-olefin random copolymer which is the component (B-1) is obtained by subjecting ethylene and an &agr;-olefin of 6-20 carbon atoms to a random copolymerization in the presence of a metallocene-based catalyst comprising a metallocene represented by the general formula (1) or (2) given below:
in which
M
1
stands for a transition metal of Group 4 of the periodic table,
R
1
and R
2
denote each, independently of each other, hydrogen atom, a halogen atom, a hydrocarbyl of 1-20 carbon atoms, a halogenated hydrocarbyl of 1-20 carbon atoms, a silicium-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group or a phosphorus-containing group,
R
3
and R
4
denote each, independently of each other, an alkyl of 1-20 carbon atoms,
X
1
and X
2
represent each, independently of each other, hydrogen atom, a halogen atom, a hydrocarbyl of 1-20 carbon atoms, a halogenated hydrocarbyl of 1-20 carbon atoms, an oxygen-containing group or a sulfur-containing group and
Y
1
stands for a divalent hydrocarbon group of 1-20 carbon atoms, a divalent halogenated hydrocarbon group of 1-20 carbon atoms, a silicium-containing divalent group, a germanium-containing divalent group, a tin-containing divalent group, —O—, —CO—, —S—, —SO—, —SO
2
—, —NR
7
—, —P(R
7
)—, —P(O)(R
7
)—, —BR
7
— or —AlR
7
—, wherein R
7
denotes hydrogen atom, a halogen atom a hydrocarbyl of 1-20 carbon atoms or a halogenated hydrocarbyl of 1-20 carbon atoms; or
in which
M
2
stands for a transition metal of Group 4 of the periodic table,
R
21
denotes, independentl
Hayakawa Youji
Tanaka Yasuo
Burns Doane , Swecker, Mathis LLP
Mitsui Chemicals Inc.
Short Patricia A.
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