Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1998-05-05
2000-10-03
Trinh, Ba K.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
549541, 549555, 549558, C07D30308
Patent
active
061275581
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to epoxy resins and, more specifically, to diglycidyl ethers of tetrabromobisphenol A (hereinafter TBBA), having a crystalline structure and a higher softening point than like prior art resins having an amorphous structure.
BACKGROUND OF THE INVENTION
Diglycidyl ethers of TBBA are known in the art and have a wide varietv of applications, such as: raw materials for self-extinguishing epoxy laminates, flame retardants for phenolic laminates and for thermoplastic materials, raw materials for modified epoxy resins, and high molecular weight epoxy resins, powder coatings, dry epoxy molding compounds, heat stabilizers for halogenated organic compounds, and so forth.
The lower the molecular weight of the brominated epoxy resins, based on tetrabromobisphenol A, the lower their softening points are. For example, when the molecular weight decreases from 4,000 to 700 g/mol, the softening point decreases from 160.degree. C. to 55.degree. C. The handling and the transportation of low softening point or semi-solid materials are both complicated and expensive, since such materials tend to stick to their containers. In some uses, such as in powder coating and solid molding compounds, there is a need for high softening point materials with high concentrations of epoxy groups, viz. with low molecular weight. It is possible, in principle, to raise the softening point by the use of additives, such as materials having a high surface area, but the presence of such material is not always acceptable, and anyway, their ability to raise to the softening point is limited.
It is a purpose of this invention to provide brominated epoxy resins based on TBBA, and specifically, diglycidyl ethers of TBBA, having a low molecular weight and a higher softening point than materials of the same molecular weight known in the prior art.
It is another purpose of this invention to provide such resins having a specific crystalline structure.
It is a further purpose of this invention to provide such resins with a high flowability in the particulate solid state (powder or flakes), that are easy to package and to transport in bulk or bags.
It is a still further purpose of this invention to provide a method for producing such resins, which is economical and has a substantially quantitative yield.
It is a still further purpose of this invention to provide a method which has a very high and practically quantitative yield.
Other purposes and advantages of this invention will appear as the description proceeds.
SUMMARY OF THE INVENTION
The epoxy resins to which this invention refers are diglycidyl ethers of tetrabromobisphenol A, having the general formula ##STR1## wherein n has an average value, in any batch of resins, between 0.0 and 0.2.
Said ethers have an epoxy equivalent weight (hereinafter EEW) between 320 and 380 g/eq and a chlorine content that is smaller than 0.3%. Epoxy equivalent weight is given, per standard definition, by the molecular weight of the substance divided by the number of epoxy groups contained therein. Such brominated epoxy resins can be produced from TBBA epichlorohydrine and sodium hydroxide as described, for instance, in Polymer Syntheses, Vol. II, S. R. Sandier and W. Karo, Academic Press Inc., ISBN 0-12618502, pp. 80-81.
The product obtained from this synthesis according to the prior art is an amorphous product and is obtained in bulk form. The invention provides a product that is an epoxy resin having the aforesaid formula and which is characterized by a specific crystalline form and has a correspondingly increased softening point, which is generally about 100.degree. and 120.degree. C.
The specific crystalline form of the product is characterized by the presence, in the diffraction pattern of the product, of the following seven strong diffraction peaks:
The invention further comprises a method for imparting to amorphous epoxy resin having the aforesaid formula, produced by prior art methods such as that hereinbefore mentioned, a crystalline structure and a consequently hi
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Stanley R. Sandler and Wolf Karo, Polymer Syntheses vol. II, Academic Press, ISBN 0-12-618502-6, pp. 80-83, 1977.
Yu.M. Cheban et al., Dokl. Akad. Nauk USSR (1985), 283(3), pp. 621-624.
Yu. N. Safyanova et al., Gor'k , Issled. Fiz.-Tekh. Inst., Gorkiy, USSR, Zh. Strukt. Khim. (1984), 25(4), pp. 156-157.
Bar-Yaakov Yoav
Plewinski Daniel
Bromine Compounds Ltd.
Trinh Ba K.
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