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
1999-10-22
2001-10-23
Seidleck, James J. (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...
C525S070000, C525S086000, C525S316000, C525S317000, C525S326500, C524S504000
Reexamination Certificate
active
06306961
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermoplastic resin composition having impact resistance, particularly to a thermoplastic resin composition having impact resistance and comprising a thermoplastic resin and graft copolymer particles having a hollow rubber portion.
BACKGROUND ART
Conventional thermoplastic resins, for example, vinyl chloride resins such as polyvinyl chloride; acrylic resins such as polymethyl methacrylate; aromatic vinyl resins such as polystyrene and styrene-acrylonitrile copolymer; carbonate resins such as polycarbonate; amide resins such as Nylon 6; polyester resins such as polyethylene terephthalate; olefin resins such as polypropylene; and polymer alloys of those resins, for example, alloy of styrene-acrylonitrile copolymer and polycarbonate, alloy of &agr;-methylstyrene-acrylonitrile copolymer and polyvinyl chloride and alloy of polystyrene and polyphenylene oxide are inherently low in impact resistance. In order to improve impact resistance of those resins and alloys thereof, generally there have been widely employed methods for adding, to rubber particles, graft copolymer particles obtained by graft-copolymerizing various monomers. Though the degree of improvement of impact resistance by the addition of the graft copolymer particles is remarkable, for further improving the impact resistance efficiently, there have been made many proposals of improving graft copolymer particles. The methods disclosed in those proposals are a method of lowering Tg of rubber particles (JP-A-2-1763, JP-A-8-100095), a method of regulating gel content of rubber particles, a method of matching particle size and particle size distribution of rubber particles in graft copolymer particles to those of thermoplastic matrix resin (S. Wu, Polymer Engineering and Science, 30,753 (1990)), a method of adjusting compatibility of graft copolymer particles with thermoplastic matrix resin (JP-A-2-251553), etc.
However improvement by those methods have reached their limits, and it is difficult to improve impact resistance more significantly. Also when an adding amount of graft copolymer particles is increased, there is a problem that other characteristics, for example, processability, weather resistance and economic efficiency are lowered.
Meanwhile crazing and shearing yield are an important factor on improvement of impact resistance of a thermoplastic resin. In order to cause such phenomena, stress concentration in a molded article is inevitable. For that purpose, rubber particles are added. Optimizing a size, shape and softness (Tg and degree of crosslinking of rubber) of rubber particles also has a great effect on the stress concentration, and it is anticipated that making a large cavity in the rubber particle previously has greater influence on the stress concentration (“Impact Resistance of Plastics” by Ikuo Narisawa, pp. 131, 155, published by Siguma Shuppan (1994)). However this proposal is hypothetical, and how it is realized is not disclosed.
In order to realize production of hollow graft copolymer particles, the present inventors have made various studies even with respect to different techniques which are not usually studied, and have found that when a technique for hollowing of particles which is known in the field of paints is applied, hollow graft copolymer particles can be prepared and that when such hollow graft copolymer particles are added to a thermoplastic resin, impact resistance can be further improved. Thus the present invention was completed.
SUMMARY OF THE INVENTION
Namely the present invention relates to the thermoplastic resin composition which has improved impact resistance, comprises a thermoplastic resin (A) and graft copolymer particles (B) having a hollow rubber portion and graft chain and contains the thermoplastic resin (A) and the graft copolymer particles (B) in a weight ratio (A) (B) of 2/98 to 100/1.
It is preferable that the graft copolymer particles comprise a particle composed of 10 to 95% (% by weight, hereinafter the same) of the hollow rubber portion and 5 to 90% of the graft chain obtained by polymerizing a vinyl monomer graft-copolymerizable with the rubber portion.
It is preferable that a volumetric proportion of hollow part in the hollow rubber portion of the graft copolymer particles is 1 to 70% by volume on the basis of the hollow rubber portion and further that the hollow rubber portions comprise hollow rubber particles having an average particle size of 50 to 2,000 nm.
It is preferable that the rubber of the hollow rubber portion constituting the graft copolymer particle is a rubber polymer of a diene rubber, acrylic rubber, silicone rubber or olefin rubber, or a rubber composition comprising 100 parts (part by weight, hereinafter the same) of a crosslinked copolymer obtained by polymerization of 0.05 to 40% of a crosslinkable monomer, 99.95 to 60% of a monomer copolymerizable with the crosslinkable monomer and 0 to 0.5% of a hydrophilic monomer and 0.05 to 50 parts of a polymer being different from the crosslinked copolymer.
Examples of the preferable starting vinyl monomer for the graft chains constituting the graft copolymer particles are a vinyl monomer comprising 60 to 100% of at least one vinyl monomer selected from the group consisting of an aromatic vinyl compound, vinyl cyanide compound, vinyl chloride and (meth)acrylate compound and 0 to 40% of other monomer copolymerizable with said monomer; or a mixture of the vinyl monomers.
The preferable thermoplastic resin which is another component of the present invention is at least one selected from the group consisting of vinyl chloride resin, aromatic vinyl resin, acrylic resin, carbonate resin, polyester resin, amide resin and olefin resin. It is preferable that the vinyl chloride resin contains vinyl chloride unit in an amount of not less than 50% and that the aromatic vinyl resin contains an aromatic vinyl unit in an amount of not less than 50%.
As the thermoplastic resin, there is also used preferably a polymer alloy containing at least one of vinyl chloride resin, aromatic vinyl resin, acrylic resin, carbonate resin, polyester resin, amide resin and olefin resin, particularly a polymer alloy of the aromatic vinyl resin and vinyl chloride resin.
DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic resin composition of the present invention which has improved impact resistance basically comprises a thermoplastic resin and graft copolymer particles.
The graft copolymer particle is composed of a hollow rubber portion and graft chain grafting on the hollow rubber portion.
The hollow rubber portion is composed of hollow rubber particle. The hollow rubber particle can be prepared by applying technique used in the field of paints. For example, there are (a) a method of preparing a W/O/W emulsion and polymerizing a monomer of the O layer (O: hydrophobic, W: hydrophilic); (b) a method of hollowing by swelling core-shell particles having a swellable core at a temperature of not less than Tg of the shell layer; (c) a method of two stage polymerization of polymers having different solubility parameters; (d) a method of finely dispersing a polymerizable monomer mixture containing a crosslinkable monomer and hydrophilic monomer and an oily substance in water to give a O/W emulsion and then polymerizing for crosslinking and removing the oily substance after the crosslinking; and (e) a method of using a phenomenon, in which a carboxylic acid unit copolymerized in the particle moves in the particle under acidic or alkaline conditions (“Application of Synthetic Latex” by Takaaki Sugimura, et al, pp. 285, published by Kobunshi Kankokai (1993)).
In the present invention, the hollow rubber particles can be prepared by any of the methods (a) to (e). From the viewpoint of not making the rubber of the hollow rubber portion hard, the methods (b) and (e) are used preferably.
According to the method (d), there is no problem in that complete hollow rubber portion is synthesized. However, when a crosslinking agent is used in much amount, there is a case of causing a prob
Mishima Ikuhiro
Takaki Akira
Tone Hiroshi
Wada Kazuhito
Yui Koji
Armstrong Westerman Hattori McLeland & Naughton LLP
Asinovsky Olga
Kaneka Corporation
Seidleck James J.
LandOfFree
Thermoplastic resin composition having impact resistance does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermoplastic resin composition having impact resistance, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermoplastic resin composition having impact resistance will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2614115