Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Process of treating scrap or waste product containing solid...
Reexamination Certificate
2003-06-17
2004-09-21
Wyrozebski, Katarzyna (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Process of treating scrap or waste product containing solid...
C521S040000, C521S040500, C521S041000
Reexamination Certificate
active
06794419
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for recycling the resin mold containing thermoplastic resin as a main component comprising mixing a rubber-like material in a thermoplastic resin which is the main component of a recycled resin mold as a recycle aid agent for recovery of the physical properties such as impact strength, non-flammability, and the like, wherein said rubber-like material has compatibility with said thermoplastic resin and has thermoplasticity so that said thermoplastic resin in which said rubber-like material is mixed can be molded
BACKGROUND OF THE INVENTION
Recycling the resin mold containing thermoplastic resin as a main component comprises collecting waste resin mold, washing and shattering said waste resin mold, pelletizing said shattered waste resin mold, and re-molding said resulting pellet. Said method for recycling the resin mold is called “material recycle” and during said process, said thermoplastic resin may be decomposed by heating in the pelletizing process, the re-mold process and the like. By heating repeatedly in said processes, molecular bond in said thermoplastic resin may be cut and the molecular weight of said thermoplastic resin may lower and in the case of the thermoplastic resin in which a rubber like component (rubber component, rubber like material, rubber like polymer, rubber like copolymer, graft copolymer) is added to improve the physical properties such as impact strength, elongation, and the like, said thermoplastic resin is such as ABS resin, HIPS resin, modified PPE resin and the like, said rubber component is oxidized and degradized (gellation) resulting in degradation of impact strength.
Further the flame-retardant and the like may be decomposed, liquefied, and vaporized or sublimated by heating and melting during the recycle process resulting on degradation of non-flammability of the thermoplastic resin.
Further many kinds of additives are combined in said thermoplastic resin and some of said additives have no compatibility with said thermoplastic resin. For instance, the pigment or the dyestuff such as titanium oxide, carbon black, iron oxide, and the like added for coloring of said thermoplastic resin, the inorganic material (inorganic filler) such as glass fiber (GF), glass beads (GB), carbon fiber (CF), talc, calcium carbonate, and the like added for increasing the rigidity of said thermoplastic resin have poor compatibility with said thermoplastic resin. When said materials are contained in said thermoplastic resin in a large amount, the physical properties of said thermoplastic resin may degrade by repeating recycling.
For instance, the waste resin mold collected may be assorted by each kind of resin and further each color of resin and then washed enough, shattered, adjusted color, and pelletized. In case where a desired amount of the virgin thermoplastic resin is added to said pelletized recycled thermoplastic resin to adjust color or the contained amount of impurities, further pigment or dyestuff may be added to said pelletized recycled thermoplastic resin or said virgin thermoplastic resin and as a result, the containined amount of said pigment or dyestuff in the blended resin of said recycled resin and said virgin resin increase resulting in degradation of impact strength.
In said material recycle system (WO9738838), it is described that said collected waste resin mold is shattered without assorting and pelletized and the resulting mold having a mixed color is coated with a paint containing a thermoplastic resin as a main component having compatibility with said resin of said mold to adjust color.
In the case of recycle of closed loop in which the recycle of said resin mold is performed repeatedly, the paint film coated on the surface of said resin mold melts and disperses in said thermoplastic resin which is the main component of said resin mold and dissolve in said thermoplastic resin since the main component of said paint film is a thermoplastic resin.
When said paint film melts and dissolves in said thermoplastic resin, the additives such as the pigment, the dyestuff and the like contained in said paint film disperses in said thermoplastic resin and as a result, the content of said pigment, dyestuff, and the like increases. Said pigment and dyestuff in said paint film have mostly poor compatibility with said thermoplastic resin, resulting in degradation of the physical properties such as impact strength, fluidity, and the like.
Content of the pigment and the dyestuff in the colored resin mold (virgin resin mold) is about 0 to 1.5% by weight while content of the pigment and the dyestuff in the dried colored paint film is about 30 to 70% by weight so that the pigment and the dyestuff content of said paint film is larger than that of said thermoplastic resin.
For instance, assuming that a paint film containing 60% by weight of the pigment and the dyestuff is formed on one side of a panel shaped mold whose thickness is 3 mm, the length and the width are 500 mm respectively. In a case where the virgin resin mold contains 0.3% by weight of the pigment and the dyestuff, the product of the weight of the virgin resin mold×the pigment and dyestuff content is 500 mm×500 mm×3 mm×1 (specific gravity)×0.3% by weight=2.25×105 .
In the case of the dried paint film, the product is 500 mm×500 mm×0.015 mm (in the case of one side coating)×1 (specific gravity)×60 Wt%=2.25×105. As above described, in the case of recycle of the coated resin mold, the pigment and dye stuff content may become twice by as much as that of one time recycle and the pigment and the dyestuff content in said thermoplastic resin which is the main component of said resin mold increases as above described, resulting in the degradation of the physical properties of the recycled resin mold since said pigment and said dyestuff have poor compatibility with said thermoplastic resin respectively (compare Table 1 with Table 2).
A paint 0001 containing styrene modified acrylic resin having the compatibility with ABS resin of said resin mold (whose formulation is shown in Table 3) was coated on a resin mold produced by the injection mold of ABS resin (Styrac 191F, Asahi Kasei Corporation.) and said coated resin mold was shattered with the paint film and pelletized to re-mold. Physical properties after said process was repeated three times are shown in Table 1. As a comparison, said process consisting of shattering, pelletizing, and re-mold of said resin mold was repeated three times without coating said paint and the result was shown in Table 2.
Referring to Tables 1 and 2, it is recognized that IZOD impact strength of said recycled resin mold with paint coating degrades comparing with that of said recycled resin mold without paint coating. The reason why impact strength of said recycled resin mold degrades seems to be the effects of the pigment and the dyestuff in said paint film.
The physical properties degrade both in a case where said resin mold is coated with paint or in a case where said resin mold is not coated with paint. Said degradation of the physical properties seems to be caused by the degradation of the rubber component in ABS resin (AnSt-g-PBD).
In the case of the resin containing the same rubber component as the rubber component of ABS resin, such as HIPS, modified PPE, and the like, said rubber component degrades by repeated heating to melt, resulting in the degradation of impact strength of said thermoplastic resin (refer to Reference 3 and others).
As above described, the reasons of the degradation of impact strength by the repeated recycling process in the “material recycle” are as follows;
(1) In the case of the recycle of the coated resin mold, the pigment and the dyestuff in the paint film migrate in said thermoplastic resin which is the main component of said resin mold during the heating and melting process to increase the content of the pigment and dyestuff having poor compatibility with said thermoplastic resin which is the main componen
Cooper & Dunham LLP
Dowden Donald S.
Suzuka Fuji Xerox Co., Ltd.
Wyrozebski Katarzyna
LandOfFree
Method for recycling the resin mold does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for recycling the resin mold, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for recycling the resin mold will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3271456