Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-06-10
2000-06-27
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 71, 525 73, 525 84, 525246, 525316, 524504, 523335, C08F27904
Patent
active
060808152
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing thermoplastic resins having high impact strength and good surface gloss. In particular, the present invention relates to a process for the fast production of thermoplastic resins having high impact strength and good surface gloss, characterized in that the process comprises graft copolymerizing a vinyl cinanide compound and an aromatic vinyl compound for less than 3 hours in the presence of a rubber latex having more than 90% of gel content. The rubber latex can be a mixture of two or more rubber lattices having different particle size.
BACKGROUND ART
It is well known in this art that, in order to improve the impact strength of thermoplastic resins such as ABS type resin or the similar resins, in the preparation thereof, thermoplastic resins such as styrene-acrylonitrile copolymer, polystyrene, polymethyl methacrylate and the like are blended with a graft copolymer. This graft copolymer is prepared by graft copolymerizing rubber latex, that is, diene-type rubber lattices such as polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer and the like.
In the U.S. Pat. Nos. 3,509,238 and 4,520,165, the use of water soluble potassium persulphate initiator is described, and the total reaction time is approximately 6 hours. U.S. Pat. No. 4,009,227 describes the use of water soluble initiator and polybutadiene rubber latex having relatively higher gel content of 85%.
However, the resulted thermoplastic resin has relatively lower impact strength, and the total reaction time is more than four hours.
Additionally, U.S. Pat. Nos. 3,928,494, 4,753,988, 4,668,738 and GB 1,501,256 have all disclosed the use of water-soluble initiator.
In these disclosures, however, the total reaction time is more than 5 hours, and the gel content of the used rubber lattices is not described.
In general, the graft polymerization as mentioned above is conducted via emulsion polymerization. It is well known in the art that the graft polymerization generally takes about 5 hours, and that shortening of said reaction time yields an insufficient degree of grafting which leads to lower dispersability when the graft polymer is blended with the thermoplastic resins. Therefore, the resulted thermoplastic resin composition has low impact strength, inferior surface gloss and poor processability due to their lower dispersability.
DISCLOSURE OF INVENTION
Thus, the object of the present invention is to provide a process for the fast production of a thermoplastic resin having high impact strength and good surface gloss without causing the above mentioned problems.
In order to achieve this object, the inventors have extensively studied and found that, if at least a vinyl cyanide compound and at least an aromatic vinyl compound are graft copolymerized for a short period of less than about 3 hours to a rubber latex having a gel content of more than 90% in the presence of a water-soluble initiator, the inner occlusion into the rubber and the level of coagulum formation are decreased, and a degree of rubber surface grafting is much increased. Thereby, the resulted thermoplastic resin has very high impact strength and good surface gloss. Furthermore, the productivity is greatly improved due to the short reaction time.
It is believed that the higher impact strength is largely due to the lower level of occlusion. This lower level of occlusion may cause easily rubber cavitation phenomena in fracture.
In addition, when a thermoplastic resin prepared according to the present invention is blended with other thermoplastic resins, the resulted resin composition also has higher impact strength and good surface gloss.
DETAILED DESCRIPTION OF THE INVENTION
Said rubber latex may be a mixture of small rubber latex and large rubber latex. Said small rubber latex can be prepared by conventional emulsion polymerization. The small rubber latex has a gel content of 90 to 100% and an average particle diameter of 0.07 to 0.15 .mu.m. Said large rubber latex can be prepared by co
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ESP@cenet-Document Bibliography and Abstract for Japanese Patent Publication No. 2-247245, Oct. 1990 (1 page).
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Kim Young-Min
Lee Chang-Hong
Yoo Jin-Nyoung
Asinovsky Olga
LG Chemical Limited
Seidleck James J.
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