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
2000-12-15
2002-09-10
Nutter, Nathan M. (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...
C525S232000, C525S240000
Reexamination Certificate
active
06448336
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to a high-cis conjugated diene polymer rubber composition to be incorporated in a resin for improving impact resistance and luster of the resin; a resin composition comprising the conjugated diene polymer rubber composition; and an impact-resistant poly-aromatic vinyl resin composition.
(2) Description of the Related Art
High-impact polystyrene resins (HIPS) are generally produced by polymerizing a styrene monomer in the presence of various unvulcanized rubbers by a bulk-solution or a bulk-suspension polymerization procedure. The thus-produced high-impact polystyrene resins have a structure such that rubber particles are dispersed in a matrix of the polystyrene resin, and therefore, the impact resistance of the hard and brittle polystyrene resin is improved. The high-impact polystyrene resins are inexpensive and have good processability and physical properties, and thus, have been widely used.
In recent years, high impact polystyrene resins are more and more widely used because of their good physical properties and processability. But, higher performances are still required for high impact polystyrene resins. The required performances are, for example, well balanced impact resistance and rigidity (i.e., modulus in flexure), enhanced low-temperature impact resistance, good appearance such as enhanced luster and reduced coloration, and enhanced resistance to thermal degradation. Further, it is required that, when a high impact polystyrene resin prepared by polymerizing a styrene monomer in the presence of a rubber as a modifier for the resin is incorporated with a polystyrene resin, the desired properties are not deteriorated or are deteriorated only to a very slight extent.
To provide a modifier for improving impact resistance and thermal resistance, an improved process for producing a polybutadiene rubber is proposed in Japanese Examined Patent Publication No. H4-14689 wherein butadiene is polymerized by using a special catalyst predominantly comprised of a rare earth metal compound to give a polybutadiene rubber having an extremely reduced 1,2-vinyl bond content and a relatively narrow molecular weight distribution. Another process for producing a polybutadiene rubber for a resin modifier is proposed in Japanese Unexamined Patent Publication No. H9-151219 wherein butadiene is polymerized in the presence of a catalyst having a special composition comprising a transition metal compound, an organic aluminum compound and water and in the co-presence of a specified amount of a molecular weight modifier and an ortho-ester to give a polybutadiene rubber having a large cis-1,4 bond content and a relatively narrow molecular weight distribution. These proposed processes provide high-impact polystyrene resins having a low-temperature impact resistance. However, the high-impact polystyrene resins have a molecular weight distribution which is not sufficiently narrow, and thus, their surface luster is not improved to a satisfied extent.
A further process for producing a polystyrene resin having an improved impact resistance is proposed in Japanese Examined Patent Publication No. H6-51768 wherein a polybutadiene rubber having a cis bond content of 15 to 35 mole % and a narrow molecular weight distribution as expressed by the ratio of Mw/Mn of 1.2 to 1.8, is produced by coupling polybutadiene with a coupling agent having at least three functionalities by using an organic lithium catalyst to a coupling degree of at least 50%. The polybutadiene rubber used has a narrow molecular weight distribution and thus results in a high-impact polystyrene exhibiting an enhanced surface luster, but, the polybutadiene rubber has a low cis-1,4 bond content, and therefore, the low-temperature impact resistance of the high-impact polystyrene resin is not improved to a sufficient extent.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a modifier for a resin which is capable of highly improving the balance between low-temperature impact resistance and luster of the resin when the modifier is incorporated in the resin.
Another object of the present invention is to provide a resin composition comprising a resin having incorporated therein the above-mentioned modifier for the resin, which exhibits a highly balanced low-temperature impact resistance and surface luster.
A further object of the present invention is to provide a resin composition comprising a poly-aromatic vinyl resin and the above-mentioned modifier for the resin, which exhibits a highly balanced low-temperature impact resistance and surface luster.
As a result of extensive research for solving the problems of the prior art, the present inventors have found (i) that the above-mentioned objects are achieved by using a modifier for the resin, which is a high-cis conjugated diene polymer rubber composition comprising a specific conjugated diene polymer having a high cis-bond unit content and a small ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn); (ii) that the high-cis conjugated diene polymer rubber composition for modifying a resin can give a resin composition having a highly balanced low-temperature impact resistance and a surface luster, when the high-cis conjugated diene polymer rubber composition is contained as a polymer elastomer ingredient in a thermoplastic resin such as a poly-aromatic vinyl resin; and further (iii) that a poly-aromatic vinyl resin composition having a highly balanced low-temperature impact resistance and a surface luster can be easily produced by subjecting the aromatic vinyl monomer alone or a mixture of the aromatic vinyl monomer with another monomer copolymerizable therewith to free-radical polymerization in the presence of the high-cis conjugated diene polymer rubber composition. Based on these findings, the present invention has been completed.
Thus, in one aspect of the present invention, there is provided a high-cis conjugated diene polymer rubber composition for modifying a resin comprising a conjugated diene polymer having a high cis-bond content, which is a polymer of a conjugated diene monomer or monomers alone or a copolymer of the conjugated diene monomer with a monomer copolymerizable therewith, and in which the content of units having a cis-bond in the total units derived from the conjugated diene monomer is at least 40%; the weight average molecular weight (Mw) is in the range of 20,000 to 10,000,000; the ratio (Mw/Mn) of weight average molecular weight (Mw) to the number average molecular weight (Mn) is smaller than 1.5; and the ratio Mw/Mn and the weight average molecular weight (Mw) satisfy the following formula (1):
log(Mw/Mn)<0.162×log(Mw)−0.682 (1)
In another aspect of the present invention, there is provided a resin composition which comprises a resin ingredient and the above-mentioned high-cis conjugated diene polymer rubber composition.
In a further aspect of the present invention, there is provided a poly-aromatic vinyl resin composition which is prepared by polymerizing alone or an aromatic vinyl monomer in combination with a monomer copolymerizable by using the high-cis conjugated diene polymer as a modifier becomes poor. The ratio (Mw/Mn) is smaller than 1.5.
BEST MODE FOR CARRYING OUT THE INVENTION
(i) High-Cis Conjugated Diene Polymeric Rubber
A high-cis conjugated diene polymer rubber used in the present invention is a polymer of a conjugated diene monomer or monomers alone, i.e., a homopolymer of a conjugated diene monomer or a copolymer of conjugated diene monomers, or a copolymer of a conjugated diene monomer with a monomer copolymerizable therewith. The high-cis conjugated diene polymer rubber comprises preferably at least 40% by weight, more preferably at least 70% by weight and most preferably at least 90% by weight, of units derived from a conjugated diene monomer.
As specific examples of the conjugated diene monomer, there can be mentioned 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-c
Nakamura Masao
Noguchi Koukichi
Toyoshima Tetsuya
Birch & Stewart Kolasch & Birch, LLP
Nutter Nathan M.
Zeon Corp.
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