Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1994-04-21
1997-03-18
Jagannathan, Vasu S.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 67, 525 82, 525309, C08F25702, C08F26506, C08L 5100
Patent
active
056124201
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for preparing a gloss-modifying acrylic resin capable of reducing the surface gloss of a thermoplastic resin such as polyvinyl chloride(PVC); and, more particularly, to a process which comprises coagulating and inter-particle crosslinking a partially crosslinked polymer latex prepared by a two-step emulsion polymerization process.
BACKGROUND ART
Various attempts have been made to develop a satisfactory method to reduce the surface gloss of a thermoplastic resin. They may include processing the thermoplastic resin at a low temperature, incorporating inorganic fillers such as silica and calcium carbonates into the resin and the like. However, the above techniques usually deteriorate the physical properties of the final products detrimentally. In order to overcome the drawback mentioned above, organic fillers such as polymeric gloss modifiers have been developed, which can reduce the gloss by virtue of their working principles that when the polymeric gloss modifier is incorporated into a thermoplastic resin(matrix resin), the polymeric modifier particles having lower thermal shrinkability than the matrix resin(e.g., PVC) sit on the top of the thermoplastic resin because of the difference in the thermal shrinkability between the polymeric modifier and the matrix resin to scatter light. Acryloid.sup.R KF-710, marketed by Rohm and Haas of the U.S., is a gloss-modifying acrylic resin prepared by a bulk polymerization process. However, the prior art scheme still suffers from various deficiencies related to the complicated process requirements involved and high manufacturing cost.
DISCLOSURE OF INVENTION
Accordingly, it is an object of the present invention to provide a process for efficiently and economically preparing a polymeric gloss modifier which can effectively reduce the surface gloss of a thermoplastic resin, which comprises: preparing a latex of partially crosslinked polymer having a semi-interpenetrating polymer network by way of first carrying out a non-crosslinking emulsion polymerization to produce a linear polymer resin of a low molecular weight and then conducting a crosslinking emulsion polymerization to produce a crosslinked polymer resin; and coagulating and inter-particle crosslinking the latex to produce a gel of a high molecular weight.
Another object of the present invention is to provide a process for preparing a low gloss thermoplastic resin compound which comprises blending a conventional thermoplastic resin with the polymeric gloss modifier obtained in accordance with the inventive process.
In accordance with one aspect of the present invention, there is provided a process for preparing a polymeric gloss modifier having a partially crosslinked structure, i.e., having both a crosslinked structure and a linear structure, which comprises:
(a) emulsion polymerizing an acrylic monomer, a cyanide compound and, optionally, an aromatic vinyl monomer to obtain a copolymer latex of a linear structure;
(b) conducting a crosslinking emulsion polymerization of the resulting linear copolymer latex obtained in step(a) with an addition of the same monomers used in step(a), an acrylamide inter-particle crosslinking agent and a crosslinking agent to produce a partially crosslinked latex; and
(c) coagulating and inter-particle crosslinking the partially crosslinked latex obtained in step(b) with an addition of an acid to obtain the polymeric gloss modifier.
In accordance with another aspect of the present invention, there is provided a process for preparing a low gloss thermoplastic resin compound which comprises blending a conventional thermoplastic resin with the polymeric gloss modifier prepared in accordance with the present invention.
Generally, preparation of resins may be carried out by employing such conventional methods as: emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization and the like. Of these, the emulsion polymerization method is preferably employed in the present invention. The nove
REFERENCES:
patent: 3732336 (1973-05-01), Duke
patent: 3923931 (1975-12-01), Fechillas
patent: 4920178 (1990-04-01), Zabrocki
patent: 5237004 (1993-08-01), Wu
Chang Yeong R.
Kim Dong O.
Yeo Jong K.
Yoo Jin N.
Jagannathan Vasu S.
Lucky Limited
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