Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-12-13
2001-12-04
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C527S105000
Reexamination Certificate
active
06326453
ABSTRACT:
INTRODUCTION AND BACKGROUND
The present invention relates to a process for producing a novolak type phenol resin with less unreacted phenol and a narrow molecular weight distribution in high yield. The novolak-type phenol resin produced according to the present invention is used as a suitable binder for molding materials, friction materials, grinding materials, sealants, etc.
Heretofore, a novolak-type phenol resin has been obtained by reaction of a phenol with an aldehyde, using an inorganic or organic acid such as hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, oxalic acid, p-toluenesulfonic acid, etc. as a catalyst. A novolak-type phenol resin can be adjusted in the molecular weight generally by changing a charge ratio of a phenol to an aldehyde, etc. but has a broader molecular weight distribution. The ordinary means for narrowing the molecular weight distribution includes a method of conducting the reaction in an organic solvent and a method of removing low-molecular weight components by steam distillation or solvent washing. In the case of the former method, no low-molecular weight novolak-type phenol resin can be obtained, whereas in the case of the latter method, the yield is considerably lowered.
An object of the present invention is to produce a novolak-type phenol resin with less unreacted phenols and a narrow molecular weight distribution in high yield.
SUMMARY OF THE INVENTION
As a result of extensive studies to attain the object, the present inventors have found a process for producing a novolak-type phenol resin, which comprises conducting reaction of a phenol with an aldehyde by use of an organophosphonic acid as a catalyst and have established the present invention.
According to a preferable mode of the present invention, reaction of a phenol with an aldehyde is carried out by keeping a water concentration of reaction system at not more than 30% by weight and a reaction temperature at 110°-200° C.
According to another preferable mode of the present invention, an organophosphonic acid represented by the following general formula (1) is used:
R—PO(OH)
2
(1)
where R is a group containing carbon atoms and at least one of —COOH and —PO(OH)
2
.
REFERENCES:
patent: 3988386 (1976-10-01), Hesse et al.
patent: 5859153 (1999-01-01), Kirk et al.
patent: 5864003 (1999-01-01), Qureshi et al.
patent: 0 789 041 A1 (1997-08-01), None
patent: 1 076 069 A2 (2001-02-01), None
patent: 08-067728 (1996-03-01), None
Condensed Chemical Dictionary, 8th Ed., p. 631, Jul. 1971.
Asami Masakatsu
Kobayashi Yoshikazu
Foelak Morton
Smith , Gambrell & Russell, LLP
Sumitomo Durez Company Ltd.
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