Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-03-03
1998-11-24
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...
525314, 5253339, C08F 800, C08F 808, C08L 5302
Patent
active
058408096
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an epoxidized block copolymer suitable for use in modifiers or modifier auxiliaries for rubbery or resinous polymers, adhesives, sealants, etc.
BACKGROUND ART
A block copolymer formed from a vinyl aromatic hydrocarbon compound and a conjugated diene compound and a hydrogenation product of the block copolymer are transparent, have the same elasticity as that of a vulcanized natural or synthetic rubber at ordinary temperatures even when it is not vulcanized and exhibits the same processability as that of a thermoplastic resin at high temperatures. Therefore, the above block copolymer is widely utilized in the field of various modifiers, adhesives, etc. To improve further the above performance of the block copolymer, the inventors have made many proposals for the use of an epoxidized block copolymer obtained by epoxidizing unsaturated carbon bonds attributed to the diene block of a block copolymer or a hydrogenation product thereof.
JP-A-5-125197 (1993) describes a (radiation)crosslinkable adhesive composition containing a polybutadiene block polymer provided with epoxy functionality and further describes that the obtained polymer can be melt-processed before it is crosslinked and has a high gel content after it is crosslinked to thereby improve the heat and solvent resistances.
However, it is described that the epoxidized block copolymer of this prior art can be one containing both epoxide and hydroxyester groups, attributed to partial opening of the epoxy ring, when the epoxidation reaction is conducted in the presence of an acid catalyst. Further, even if an epoxidized block copolymer having a low gel content is obtained before the crosslinking, further gelation may occur during the subsequent molding through heat melting. This gelation causes a drawback that moldability is gravely deteriorated.
DISCLOSURE OF THE INVENTION
The present invention provides an epoxidized block copolymer (E) obtained by epoxidizing a block copolymer (C) comprising a polymer block (A) composed mainly of a vinyl aromatic hydrocarbon compound and a polymer block (B) composed mainly of a conjugated diene compound or a hydrogenation product (D) thereof, meeting at least one of the following requisites: from 0.001 to 0.1, the molar ratio (R) being represented by the formula: the mole number of epoxy groups contained per unit weight of the epoxidized block copolymer;
Preferably, the epoxidized block copolymer (E) is provided, further meeting at least one of the following requisites: and
It is preferred that the hydrogenation product, being hydrogenated in part, have a hydrogenation ratio of 20 to 99% in the block (B) unit; that the molar ratio (R) range from 0.001 to 0.05; that the acid value be not greater than 5 mgKOH/g; and that the gel content range from 0.0001 to 1% by weight per copolymer unit.
Moreover, the present invention provides a process for producing an epoxidized block copolymer, which comprises the steps of:
(1) mixing the above block copolymer (C) or a hydrogenation product (D) thereof with an organic solvent so as to obtain an organic solvent solution or organic solvent slurry having a polymer concentration of 5 to 50% by weight;
(2) epoxidizing unsaturated carbon bonds contained in the above polymer block (B) with use of an epoxidizing agent in the organic solvent solution or organic solvent slurry; and
(3) evaporating off the organic solvent from the reaction mixture to thereby obtain an epoxidized block copolymer.
The epoxidation reaction mixture obtained in the step (2) in the form of a solution or slurry can be washed with water and/or neutralized so that the acid value of the solution or slurry may not exceed 5 mgKOH/g prior to being fed to the step (3). Thus, the above epoxidized block copolymer can be obtained. In particular, the epoxidized block copolymer which meets at least one of the above requisites (1), (2) and (3) can be obtained.
In the process of the present invention, a phenolic stabilizer and/or a phosphorous stabilizer can be added to the epo
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Ohtsuka Yoshihiro
Oshino Yasuhiro
Tanaka Masaki
Daicel Chemical Industries Ltd.
Zemel Irina S.
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