Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1996-03-22
1998-05-05
Zemel, Irina S.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525244, 525316, C08F27902
Patent
active
057475938
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing a rubber-modified styrene resin in which the impact resistance is well balanced with the elastic modulus.
BACKGROUND ART
In a process for producing rubber-modified styrene resins, a rubbery polymer is dissolved in an aromatic monovinyl series monomer, and the solution is subjected to bulk or solution polymerization which turns the rubbery polymer into dispersed rubber particles and is further followed by bulk or solution polymerization, or suspension polymerization. However, since bulk or solution polymerization is a continuous polymerization system, it is more efficient and economical then suspension polymerization, which is usually a batch-wise polymerization system, but it is inferior in producing a proper balance between the impact resistance and the elastic modulus of the resulting resin.
U.S. Pat. No. 3,144,420 and the Japanese patent No. Sho. 60-398282 disclose processes in which a polystyrene polymer is added to raw materials before starting polymerization in a continuous polymerization process. However, since in these processes a rubbery polymer is subjected to phase inversion to turn into dispersed particles, the diameter size distribution of the rubber particles dispersed in a resin is broad, and the effect of an improvement in a balance between the impact resistance and the elastic modulus of a resultant resin is insufficient.
The Japanese Patent 62-34327, using a similar process, discloses a process for improving the coloring property of a resin in which a combination of a rubbery polymer and an aromatic monovinyl series monomer is mixed with a styrene polymer solution (which maintains the system at a partial polymerization stage) to force the rubbery polymer into dispersed particles and further continue polymerization. However, this process is still insufficient in terms of an effect of the improvement in a balance between an impact resistance and an elastic modulus. The present invention relates to a process for producing rubber-modified styrene resins in which such conventional techniques as described above are improved.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a process for producing, in a continuous bulk polymerization system, rubber-modified styrene resins in which a distribution in the diameters of rubber particles is narrow and the impact resistance is well balanced with the elastic modulus. We have found that the polymerization reaction which takes place before the polymerization conversion rate reaches a rate in which the rubber phase of the rubbery polymer is inverted from a continuous phase to a dispersion phase, exerts very large influence in controlling the shape of the styrene resin of the rubber particles and the diameter distribution of the rubber particles.
It has been found that the object described above can be achieved by supplying a solution prepared by mixing a rubber syrup solution, comprising an aromatic monovinyl series monomer and a rubbery polymer, with a styrene polymer in a specific range in a plug flow type reactor and promoting the polymerization in such a specific condition that the rubber phase is inverted. The present invention has been completed based on this knowledge.
That is, the present invention relates to a process for producing a rubber-modified styrene resin, comprising: solvent blended with 100 weight parts of a mixed solution--which itself is prepared by mixing an aromatic monovinyl series monomer, a rubbery polymer and a styrene polymer in the ranges of 60 to 95 weight %, 3 to 10 weight %, and 2 to 30 weight %, respectively and which is adjusted so that the relation of the content R (wt. %) of the rubbery polymer contained in said mixed solution with the content Ps (wt. %) of the styrene polymer satisfies 0.2<Ps/R<3--and a state before rubber phase inversion is maintained, subjecting said solution to preheating treatment up to 70.degree. to 120.degree. C. with a pre-heater so that a condition before the rubber phase inversion c
REFERENCES:
patent: 3144420 (1964-08-01), Fryling
Fujita Masanari
Nozawa Masayuki
Shichijo Yasuji
Nippon Steel Chemical Co. Ltd.
Zemel Irina S.
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