Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-05-28
2003-06-10
Mullis, Jeffrey (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S323000, C524S505000, C525S088000, C525S09200D, C525S09200D, C525S093000, C525S099000, C525S314000, C525S316000, C525S332900
Reexamination Certificate
active
06576692
ABSTRACT:
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:
(1) having a molar ratio (R) of existing hydroxyl to existing epoxy ranging from 0.001 to 0.1, the molar ratio (R) being represented by the formula:
R=[hydroxyl]/[epoxy]
wherein [hydroxyl] represents the mole number of hydroxyl groups contained per unit weight of the epoxidized block copolymer and [epoxy] represents the mole number of epoxy groups contained per unit weight of the epoxidized block copolymer;
(2) having a gel content of not greater than 5% by weight; and
(3) having a chloride (chlorine) ion content of not greater than 7 ppm.
Preferably, the epoxidized block copolymer (E) is provided, further meeting at least one of the following requisites:
(4) having an acid value of not greater than 10 mgKOH/g;
(5) having a residual organic solvent content of not greater than 5000 ppm; and
(6) having an epoxy equivalent of 140 to 2700.
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 epoxidation reaction mixture before the organic solvent is directly evaporated off from the epoxidation reaction mixture. Preferably, in the step (3), a phenolic stabilizer and/or a phosphorous stabilizer can be added to the epoxidation reaction mixture in an amount of 0.005 to 5 parts by weight per 100 parts by weight of the finally obtained epoxidized block copolymer before the organic solvent is removed from the epoxidation reaction mixture. Further, preferably, the step (3) can be conducted in such a manner that the epoxidation reaction mixture in the form of a solution or slurry is quantitatively fed into an evaporator; a phenolic stabilizer and/or a phosphorous stabilizer is added to the epoxidation reaction mixture in an amount of 0.005 to 10 parts by weight per 100 parts by weight of the finally obtained epoxidized block copolymer; and the organic solvent is removed from the epoxidation reaction mixture. A preferred epoxidizing agent is an acetic ester solution containing peracetic acid but not containing water.
In the step (3), the epoxidation reaction mixture can be fed into an evaporator to thereby directly evaporate off the organic solvent. The evaporation is conducted by heating. This solvent's removal preferably involves one or two stages of operation.
The two-stage solvent's removal can be conducted in such a manner that in the step (3), the epoxidation reaction mixture is fed into an evaporator to thereby evaporate the organic solvent so that the epoxidation reaction mixture is concentrated and the concentrate is fed into a kneading evaporator to thereby remove the organic solvent. In the step (3), each of the evaporator and kneading evaporator can be at a temperature of 80 to 300° C. and an internal pressure of not greater than 500 Torr. Preferably, in the step (3), the epoxidation reaction mixture is fed into a thin-film evaporator to thereby evaporate the organic solvent so that the epoxidation reaction mixture is concentrated and the concentrate is fed into a vented twin-screw extruder as one type of kneading evaporator to thereby remove the organic solvent.
The one-stage solvent's removal can be conducted by, in the step (3), feeding the epoxidation reaction mixture into an evaporator which is preferred to be a vented twin-screw extruder. This vented twin-screw extruder can have such a structure that a heating medium can be passed through the internal part of each screw.
Moreover, the present invention provides an epoxidized block copolymer composition comprising 100 parts by weight of an epoxidized block copolymer (F) 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) of the block copolymer (C), 0.005 to 10 parts by weight of at least one phenolic and/or phosphorous stabilizer and/or 0.001 to 5 parts by weight of at least one antiblocking agent.
That is, the epoxidized block copolymer (E) or (F) is useful as an additive to adhesives, sealants, coatings and asphalt.
The inventors have made intensive studies and as a result have found that the ratio of hydroxyl groups to epoxy groups of the epoxidized block copolymer exerts a substantial influence on the amount of formed gel. The first embodiment of the present invention has been completed on the basis of this finding.
Illu
Ohtsuka Yoshihiro
Oshino Yasuhiro
Tanaka Masaki
Birch & Stewart Kolasch & Birch, LLP
Daicel Chemical Industries Ltd.
Mullis Jeffrey
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