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
1998-09-30
2001-03-20
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C524S505000, C525S088000, C525S089000, C525S323000
Reexamination Certificate
active
06204336
ABSTRACT:
TECHNICAL FIELD
This invention relates to a high rigidity ethylene-propylene block copolymer having excellent in rigidity, impact resistance and fluidity.
BACKGROUND ART
Polypropylene (including ethylene-propylene block copolymers) has excellent characteristics and is relatively inexpensive, and hence, has been widely used in automobile outer plate materials and interior trim materials. However, the wall-thinning of a polypropylene molded article is now proceeding as the molded article has been made large in size and light in weight.
Therefore, a high rigidity polypropylene excellent in rigidity and impact resistance has been desired.
The present situation is that when a high melt-fluidity polypropylene has been produced by polymerization, the polypropylene is very brittle and there has not been obtained such a polymer as to withstand the practical use. On the other hand, as a method of improving the melt-fluidity, there has been known a method which comprises adding a small amount of an organic peroxide to a low melt-fluidity polypropylene or its composition and heat-treating the mixture. However, the polypropylene obtained by such a method is remarkably low in rigidity and, in addition, has a problem of an odor due to the heat-treatment and in addition such a problem that a flow mark is caused on the surface of an injection molded article, or the like. Accordingly, it has been strongly desired to develop a polypropylene excellent in rigidity, impact strength, melt-fluidity and the like without requiring such a heat treatment.
DISCLOSURE OF INVENTION
In view of such a situation of prior art, it is an object of this invention to provide an ethylene-propylene block copolymer excellent in rigidity and impact strength and also good in melt-fluidity, and provide a process for producing the same.
According to this invention, there is provided a high rigidity ethylene-propylene block copolymer which is composed of (I) a crystalline polypropylene portion and (II) an ethylene-propylene random copolymer portion, and in which the crystalline polypropylene portion (I) has a Q value of not more than 5 which is the weight average molecular weight (Mw)
umber average molecular weight (Mn) ratio obtained by a gel permeation chromatography (GPC) method, an isotactic pentad fraction of the crystalline polypropylene portion (I) of not less than 0.98 as calculated from
13
C-NMR, an intrinsic viscosity of 0.6 to 0.88 dl/g as measured at 135° C. in tetralin; the ethylene-propylene random copolymer portion (II) has an intrinsic viscosity of 4.0 to 6.0 dl/g as measured at 135° C. in tetralin and an ethylene/propylene weight ratio of 25/75 to 35/65; and when the total of the polymers [(I)+(II)] is taken as 100% by weight, the proportion of the ethylene-propylene random copolymer portion (II) is 8 to 22% by weight.
According to this invention, there is also provided a process for producing a high rigidity ethylene-propylene block copolymer which comprises effecting reaction for producing (I) a crystalline polypropylene portion using a solid catalyst comprising, as the essential components, magnesium, titanium, a halogen and an aluminum compound, in the presence of a solvent and subsequently effecting reaction for producing (II) an ethylene-propylene random copolymer portion, characterized by controlling the reaction conditions so that the crystalline polypropylene portion (I) and the ethylene-propylene random copolymer portion (II) have the above-mentioned respective characteristics. This invention is explained in more detail below.
The ethylene-propylene block copolymer in this invention comprises (I) a polypropylene portion composed of a propylene homopolymer or a copolymer of propylene and not more than 1 mole % of ethylene or an &agr;-olefin having 4 or more carbon atoms (for example, butene-1, hexene-1 or the like), and (II) an ethylene-propylene random copolymer portion in which the composition of ethylene and propylene is such that the ethylene/propylene weight ratio is 25/75 to 35/65; and the ethylene-propylene random copolymer portion (II) is contained in a proportion of 8 to 22% by weight based on the overall polymer.
In this invention, the ethylene-propylene block copolymer is obtained by reacting the monomers in two steps in the presence of a solid catalyst system comprising, as the essential components, magnesium, titanium, a halogen and an aluminum compound. The catalyst is preferably a catalyst system comprising (A) a trivalent titanium compound-containing solid catalyst component (a complex of titanium trichloride and magnesium), (B) an organoaluminum compound and (C) an electron-donating compound.
A method for producing this catalyst system is described in detail in, for example, JP-A-61-218,606, JP-A-1-319,508 and the like.
That is to say, it is a catalyst system comprising (A) a trivalent titanium compound-containing solid catalyst component obtained by treating, with an ester compound, an ether compound and titanium tetrachloride, a solid product obtained by reducing a titanium compound represented by the general formula Ti(OR
1
)
n
X
4-n
wherein R
1
represents a hydrocarbon group having 1 to 20 carbon atoms, X represents a halogen atom and n is 0<n≦4, with an organomagnesium compound in the coexistence of a silicon compound having a Si—O bond and an ester compound; (B) an organoaluminum compound; and (C) an electron-donating compound.
The titanium compound used in the synthesis of the above solid catalyst component (A) is a compound represented by the above-mentioned general formula and R
1
is preferably an alkyl group having 2 to 18 carbon atoms or an aryl group having 6 to 18 carbon atoms. As the halogen atom represented by X, chlorine, bromine and iodine can be exemplified, and among them, chlorine is particularly preferable.
The value of n of the titanium compound represented by the above-mentioned general formula is 0<n≦4, preferably 2≦n≦4, and particularly preferably n=4.
The organosilicon compound having a Si—O bond used in the synthesis of the above solid catalyst component (A) is a compound represented by the general formula Si(OR
2
)
m
R
3
4-m
, R
4
(R
5
2
SiO)
p
R
6
3
or (R
7
2
SiO)
q
wherein R
2
represents a hydrocarbon group having 1 to 20 carbon atoms; R
3
, R
4
, R
5
, R
6
and R
7
are hydrocarbon groups having 1 to 20 carbon atoms or hydrogen atoms; m is 0<m≦4; p is an integer of 1 to 1,000; and q is an integer of 2 to 1,000.
Specific examples of the organosilicon compound include tetramethoxysilane, dimethyldimethoxysilane, diethoxydiethylsilane, diethoxydiphenylsilane, triethoxyphenylsilane, cyclohexylethyldimethoxysilane, phenyltrimethoxysilane and the like, and among these organosilicon compounds, preferable are alkoxysilane compounds represented by the general formula Si(OR
2
)
m
R
3
4-m
. In this formula, 1≦m≦4 is preferred, and tetra-alkoxysilane compounds corresponding to m=4 are particularly preferred.
As the organomagnesium compound used in the synthesis of the above solid catalyst component (A), there can be used any type organomagnesium compound having a magnesium-carbon bond. In particular, Grignard compounds represented by the general formula R
8
MgX in which R
8
represents a hydrocarbon group having 1 to 20 carbon atoms and X represents a halogen, and dialkylmagnesium compounds or dialkylmagnesium compounds represented by the general formula R
9
R
10
Mg in which R
9
and R
10
represent hydrocarbon groups having 1 to 20 carbon atoms are suitably used. In the above formula, R
9
and R
10
may be the same or different.
As the ester compound used in the synthesis of the above solid catalyst component (A), there are mentioned mono- and polycarboxylic acid esters such as aliphatic carboxylic acid esters, olefinic carboxylic acid esters, alicyclic carboxylic acid esters, aromatic carboxylic acid esters and the like. Among these ester compounds, preferable are olefinic carboxylic acid esters such as methacrylic acid esters, maleic acid esters and the like and phthalic acid esters, and part
Doi Teruhiko
Hirakawa Manabu
Hisayama Tetsuya
Miyake Yuichi
Nishio Takeyoshi
Niland Patrick D.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Sumitomo Chemical Company
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