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
2001-10-03
2004-03-09
Seidieck, 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...
C525S068000, C525S069000, C525S319000, C521S047000
Reexamination Certificate
active
06703445
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a molding thermoplastic resin material for recycled resin mold having substantially equal quality to original resin mold and further relates to a method for equal quality recycling of thermoplastic resin mold.
BACKGROUND Of THE INVENTION
There are three kinds of recycle system of discarded thermoplastic resin mold. One system is chemical recycling system such as decomposition of thermoplastic resin of said discarded resin mold to produce a monomer or chemical treatment of said discarded resin mold to produce a useful product, a second system is thermal recycling in which thermal energy produced by combustion treatment of said discarded resin mold is utilized, and a third system is material recycling system in which said discarded resin mold is shattered and heated and melted for such as pelletizing to re-use molded material. Said chemical recycling system has disadvantage that chemical treatment is necessary and said thermal recycling system has problem of atmospheric pollution when said discarded resin mold is burned so that material recycling may be the most preferable recycling system. In said material recycling, especially equal quality recycling is preferable, in which thermoplastic resin mold recycled from discarded virgin resin mold has substantially the same quality and value.
PRIOR ART
In recycle process of said discarded resin mold, said discarded resin mold may be shattered, if necessary heated and melted and pelletized. Accordingly, temperature higher than the softening point or melting point, mechanical stress such as agitation, pressure, and the like may have effect on said thermoplastic resin of said resin mold. By accumulation of said thermal stress and mechanical stress, said thermoplastic resin may be denatured and the mechanical properties such as impact strength of resulting resin mold may be degraded.
Especially, impact strength of acrylonitrile-butadiene-styrene resin (ABC), high impact polystyrene (HIPS) including styrene-graft-butadiene rubber and the like degrade remarkably by repeated recycle since said resins contain butadiene rubber having poor thermal stability.
Further, the mixture, polymer blend, or polymer alloy of said thermo plastic resins including said butadiene rubber and polyphenylene ether (PPE), polycarbonate (PC), polyamide(PA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polysulfone (PSF), polyetherimide (PEI), polypropylene (PP) and the like are frequently used as molding materials but the mechanical properties of said mixture, polymer blend, or polymer alloy are apt to be degraded by thermal degradation of butadiene rubber contained in said mixture, polymer blend or polymer alloy.
Further, two mechanical properties of polymer blend or polymer alloy of thermoplastic resin containing said butadiene rubber and polyester group resin are more remarkably degraded by recycling since said polyester group resin is apt to be hydrolyzed.
Currently, a method has been provided to prevent the degradation of mechanical properties, especially impact strength of said thermoplastic plastic resin during said recycling in which rubber or thermoplastic elastomer having compatibility with said thermoplastic resin is added as a recycle aid agent.
Nevertheless, said traditional method in which said recycle aid agent is added in each recycle stage has problems in that a lot of labour and time are necessary and material cost may become great in said traditional method. Further, the content of said recycle aid agent in said thermoplastic resin may increase during repeated recycle process so that the mechanical properties of said resin mold is affected and equal quality recycling cannot be attained and only the resin mold having low quality can be provided.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a recycled resin mold which has substantially the same quality as original resin mold. Said recycle system may be called equal quality recycle system.
To attain said object, the present invention provide a molding thermoplastic resin material for recycled resin mold having substantially equal quality to original resin mold consisting of molding thermoplastic resin material in which olefin group rubber and/or acrylic rubber is(are) added as equal quality recycle aid agent wherein the same or similar monomer(s) as(to) monomers composing said thermoplastic resin is(are) graft-copolymerized to give said olefin group rubber and/or acrylic rubber compatibility with said molding thermoplastic resin material.
Diene group may be added in said molding thermoplastic resin material and it is desirable that IZOD impact strength (ASTM-D256) of said molding thermoplastic resin material is maintained at virgin thermoplastic resin's IZOD impact strength of 70% or over after said thermoplastic resin material is heated at 250° C. for 1.0 hour. Further it is desirable that a graft ratio of said monomer(s) to said olefin group rubber and/or acrylic rubber is 20% and over by weight. Still further it is desirable that said molding thermoplastic resin material is styrene group polymer and said equal quality recycle aid agent is styrene group monomer graft-copolymerized olefin group rubber and/or acrylic rubber or said molding thermoplastic resin material is nitrile group monomer and styrene group monomer copolymer and said equal quality recycle aid agent is nitrile group monomer and styrene group monomer graft-copolymerized olefin group rubber and/or acrylic rubber. Further, for instance, said molding thermoplastic resin material is polyphenylene ether group resin or polymer alloy of polyphenylene ether and polystyrene and said equal quality recycle aid agent is styrene graft-copolymerized olefin group rubber and/or acrylic rubber and said equal quality recycle aid agent is rubber-like polymer in which styrene group monomer and/or nitrile group monomer is (are) graft-copolymerized to ethylene-propylene copolymer and/or ethylene-propylene-diene terpolymer, and it is desirable that said ethylene-propylene-diene terpolymer is ethylene-propylene-dicyclopentadiene terpolymer. Still further it is desirable that a molar ratio of ethylene/propylene in said ethylene-propylene copolymer or said ethylene-propylene-diene terpolymer is 60/40 and over and Mooney viscosity (ML
1+4
, 100° C.) of said ethylene-propylene copolymer or ethylene-propylene-diene terpolymer is in the range of 5 to 150. Still further it is desirable that a molar ratio of n-butyl acrylate/butadiene of said acrylic rubber is 50/50 and over and nitrile group monomer and styrene group monomer are graft-copolymerized to said acrylic rubber in a weight ratio in the range of 20/80 to 30/70. Further the present invention provides a method for equal quality recycle of thermoplastic resin mold comprising molding by using molding material of discarded resin mold of said thermoplastic resin material in accordance with claim
1
to
12
to produce a resin mold having substantially equal quality to former resin mold. It is desirable that IZOD impact strength (ASTM-D256) of said resin mold is 90% and over of said preceding resin mold.
Said olefin group rubber and acrylic rubber have poor compatibility with polystyrene group resin such as polystyrene (PS), nitrile group monomer-styrene group monomer copolymer such as acrylonitrile-styrene copolymer (AS), polyphenylene ether, and the like so that the same or similar monomer(s) as(to) monomer(s) composing said polystyrene group resin is(are) graft-copolymerized to said rubbers to give compatibility with said rubbers. For instance, in the case of polystyrene, styrene group monomer is graft-copolymerized to said olefin group rubber or said acrylic rubber and in the case of acrylonitrile-styrene copolymer, nitrile group monomer and styrene group monomer are graft-copolymerized to said olefin group rubber or acrylic rubber, and further in the case of polyphenylene ether or polyphenylene ether modified by styrene group resin, and the like, styrene group monomer which f
Asinovsky Olga
Cooper & Dunham LLP
Dowden Donald S.
Seidieck James J.
Suzuka Fuji Xerox Co., Ltd.
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