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
1999-06-04
2002-10-22
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
24, 24, C526S943000
Reexamination Certificate
active
06469100
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a block copolymer comprising a polypropylene and an ethylene-propylene copolymer. More particularly, the present invention relates to a block copolymer having a good impact resistance.
BACKGROUND OF THE INVENTION
Most block copolymers having two or more polymers mutually connected to each other (including not only those having PP block and EPR block actually connected to each other but also apparent block copolymers having PP block and EPR block dispersed in one polymer particle obtained by continuous polymerization) exhibit far excellent properties than single mixture of homopolymers constituting these block copolymers while maintaining the characteristics of these homopolymers. Therefore, many attempts have been made on these block copolymers for the purpose of improving the properties and function of polymers.
On the other hand, most resin compositions which are obtained by blending two or more kinds of resins to improve impact resistance while maintaining the rigidity of polypropylene as a crystalline resin (often called “polymer blend”, “polymer alloy”, etc.) can have its constituent resins to compensate for defects each other while maintaining the advantages of the constituent resins. Various studies have been made of these resin compositions.
Among these resin compositions, those obtained by blending PP resin as a crystalline resin and EPR as a rubber component exhibit different properties with the kind and characteristics of these components. Accordingly, it has been necessary that studies be made of the blend of these components on a trial and error basis.
In particular, such a resin composition, if used for purposes such as structural material, must exhibit some impact resistance and rigidity at low temperatures. However, no techniques for balancing the two properties on a high level have been established.
Most resin compositions obtained by melt-mixing two or more kinds of resins (often called “polymer blend”, “polymer alloy”, etc.) can have its constituent resins to compensate for defects each other while maintaining the advantages of the constituent resins. Various studies have been made of these resin compositions (“Polymer Alloy”, page 62, Kyoritsu Shuppan, 1988). This polymer blending technique is liable to change in the resulting composition and molded products thereof with its blending and kneading methods, not to mention the properties and amount of resins to be blended.
Further, even if the foregoing technique on block copolymer is simply applied, no block copolymers having desired properties can be obtained. Thus, no block copolymers having high rigidity and impact resistance well balanced have been found.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a polypropylene block copolymer or resin composition excellent in impact resistance and rigidity.
The foregoing object of the present invention will become more apparent from the following detailed description and examples.
In order to solve the foregoing problems, the inventors made extensive studies of polypropylene block copolymers and the relationship between the crystal structure, molecular structure, etc. of various blocks constituting these polypropylene block copolymers. As a result, it was found that the foregoing object of the present invention can be accomplished by controlling the properties of these blocks to a predetermined range. The present invention has thus been worked out.
The essence of the present invention lies in a block copolymer comprising one or more blocks of a polymer made of a polypropylene (hereinafter referred to as “PP block”) and one or more blocks of a polymer made of an ethylene-propylene copolymer (hereinafter referred to as “EPR block”) connected to each other, characterized in that said block copolymer and each of said blocks have the following properties (1) to (7):
(1) The thickness of the interface of PR block with EPR block in the dispersion structure of the block copolymer is from not less than 20 nm to not more than 1,000 nm;
(2) The weight-average molecular weight of the polypropylene in PP block (hereinafter referred to as “M
W.PP
”) is from not less than 10,000 to not more than 1,000,000;
(3) The proportion of mesopentad chain in the polypropylene in PP block is not less than 95%;
(4) The particle diameter of the disperse phase of the ethylene-propylene copolymer in EPR block is from not less than 0.2 &mgr;m to not more than 3 &mgr;m as calculated in terms of weight-average area;
(5) The weight-average molecular weight of the ethylene-propylene copolymer in EPR block (hereinafter referred to as “M
W.R
”) is from not less than 50,000 to not more than 1,000,000;
(6) The propylene content in the ethylene-propylene copolymer in EPR block is from not less than 20 mol-% to not more than 80 mol-%; and
(7) The composition fluctuation in molecular weight of the ethylene-propylene copolymer in EPR block is within ±5% from the average composition.
In another attempt to solve the foregoing problem, the inventors made extensive studies of the crystal structure, dispersion state, etc. of a composition comprising as main components a polypropylene resin (PP resin) and an ethylene-propylene copolymer rubber (EPR). As a result, it was found that the foregoing object of the present invention can be accomplished by controlling predetermined properties of the resin composition and its constituents to a predetermined range. The present invention has thus been worked out.
The essence of the present invention also lies in a resin composition comprising as main components a polypropylene resin and an ethylene-propylene copolymer rubber in an amount of from 5 to 100 parts by weight based on 100 parts by weight of said PP resin, characterized in that said composition and each of said various components have the following properties (1) to (7):
(1) The weight-average molecular weight of PP resin (hereinafter referred as “M
W.PP
”) is from not less than 10,000 to not more than 1,000,000;
(2) The proportion of mesopentad chain in PP resin is not less than 95%;
(3) The weight-average molecular weight of EPR (hereinafter referred to as “M
W.R
”) is from 50,000 to 1,000,000;
(4) The propylene content in EPR is from not less than 20 mol-% to not more than 80 mol-%;
(5) The fluctuation in molecular weight of EPR is within ±5% from the average composition;
(6) The thickness of the interface of PP resin component with EPR resin component in the dispersion structure of the resin composition is from not less than 20 nm to not more than 1,000 nm; and
(7) The particle diameter of the disperse phase of EPR in the resin composition is from not less than 0.2 &mgr;m to not more than 10 &mgr;m as calculated in terms of weight-average area.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be further described hereinafter.
The polypropylene block copolymer according to the present invention is characterized by the dispersion state of the interface of PP block with EPR block.
On the other hand, the resin composition according to the present invention is characterized not only by each of its constituent PP resin and EPR components but also by the dispersion state of the various components in the dispersion structure of the composition and the state of the interface of these components.
The properties of these components will be described hereinafter. Since PP block and PP resin have the same characteristics and EPR block and EPR have the same characteristics, PP block and PP resin will be generically termed as “PP moiety” and EPR block and EPR will be generically termed as “EPR moiety”.
In other words, the crystal and dispersion structure of block copolymer or resin composition has a lamellar acicular crystal derived from PP moiety penetrating into EPR moiety at the interface of PP moiety with EPR moiety.
In the present invention, the length of the acicular penetration structure (hereinafter referred to as “interface thickness”) is controlled to a range of from not less than 20 nm to n
Nakano Hiroshi
Sano Hironari
Seki Motohiro
Sugano Toshihiko
Suzuki Toru
Gorr Rachel
Japan Polychem Corporation
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