Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-05-11
2002-04-30
Lovering, Richard D. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C525S486000, C560S301000
Reexamination Certificate
active
06380344
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to polyfunctional cyanate ester (herein-after, referred to as “cyanate ester”) compositions providing a cured product which is excellent in mechanical properties, and to cured products thereof. The cyanate ester composition of the present invention is particularly useful as an encapsulating material, a material for laminated boards, a structure material and a paint material.
2. Description of the Related Art
A cyanate esters have been mainly used as insulation materials for printed circuit boards because of their high glass transition temperatures and low dielectric properties. In this case, the cyanate ester is usually modified with other components and used in a composition. Further, as a composition of a cyanate ester and an epoxy resin, Japanese Patent Publication (Kokoku) No.46-41112 has been known as providing one such modification method.
A cyanate ester is usually produced by a reaction of a poly-valent phenol with a cyanogen halide.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a composition that is capable of producing a cured product which is excellent in mechanical properties, and a cured product thereof.
The present inventors have studied intensively and as a result, found that a cured product which is particularly excellent in mechanical properties is produced in combination with an epoxy resin by using a cyanate ester in which the total content of impurities containing imino carbonates, alkyl cyanamides, partially substituted cyanates and phenols is reduced to 5% or less, and thereby have completed the present invention.
The present invention relates to a cyanate ester composition, comprising (A) a cyanate ester in which the total content of imino carbonates, alkyl cyanamides, partially substituted cyanates and phenols as impurities is reduced to 5% or less, or a prepolymer thereof, and (B) an epoxy resin as essential components, and a cured product thereof.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is illustrated in detail below.
The cyanate ester(A) used in the present invention is a cyanate ester in which the total content of imino carbonates, alkyl cyanamides, partially substituted cyanates and phenols as impurities is 5% or less.
The cyanate ester is a compound having at least two cyanate ester groups, with examples thereof including difunctional cyanate compounds such as 2,2-bis(4-cyanatophenyl)propane, 1,1-bis(4-cyanatophenyl)ethane, bis(4-cyanato-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatophenyl-1-(methylethylidene))benzene, bis(4-cyanatophenyl) thioether, bis(4-cyanatophenyl)ether and the like; and polyfunctional cyanate compounds derived from a phenol novolac, a cresol and the like, but the same is not limited thereto.
Any cyanate ester (A) in the present invention can be used, but a cyanate ester(A) derived from bisphenol A is preferable from the viewpoint of reactivity and heat resistance, in particular.
The cyanate ester used in the present invention may be used as it is, that is, as a monomer or as a prepolymer thereof.
Such a prepolymer can be obtained by heating the cyanate ester alone or in a mixture of 2 or more of the cyanate esters in a solvent or without a solvent at 50 to 200° C., or by heating them in a solvent or without a solvent at about 50 to 200° C. in the presence of a curing catalyst (C) as described below.
The cyanate ester used in the present invention has the total content of imino carbonates, alkyl cyanamides, partially substituted cyanates and phenols of 5% or less as impurities. Preferably the total content of all impurities is 5% or less. But, the impurities being maintained at the low total level of 5% or less may consist essentially of imino carbonates, alkyl cyanamides, partially substituted cyanates and phenols.
The cyanate ester can be obtained, for example, by carrying out a de-hydrohalogenation of a phenol as a raw material with a cyanogen halide represented by cyanogen chloride or cyanogen bromide in an appropriate solvent. However, the cyanate ester which is obtained by this method occasionally contains a remarkable amount of impurities depending on production conditions such as reaction temperature, solvent utilized and the like. Accordingly, when a compound is used in the present invention, the total content of imino carbonates, alkyl cyanamides and partially substituted cyanates(cyanate monoesters) as by-products and unreacted phenols in the cyanate ester is required to be 5% or less.
The content of the impurities can be reduced to be 5% or less, by properly selecting the kind of solvent used in a crystallization step and washing step after the synthesis of the cyanate ester. Further, the kind of a solvent differs depending upon the system of reaction and the kind of the cyanate ester being utilized.
The content, in other words, purity of the cyanate ester used in the present invention is determined by using a high speed liquid chromatography method (LC) or a gas chromatography method (GC). Contents were determined by the peak area ratio of respective components to the total peak area (set as 100) derived from the synthesized product of a chromatogram. Specific measurement conditions may be properly selected depending on the kind of the compound, and in LC, the content can be measured by changing the condition of a mobile phase, depending upon the kind of the compound used, for example among the conditions indicated in the Examples herein provided.
Any epoxy resins (B) in the present invention can be used, and epoxy resins obtained by any known processes can be also used.
There is illustratively mentioned a process which comprises reacting a phenol or its derivative with an epihalohydrin in the presence of an alkali such as sodium hydroxide or the like, as a common process for producing an epoxy resin, but the present invention is not limited thereto.
Examples of the epoxy resin include epoxy resins represented by the structural formula (1) or (2) below:
wherein, n is an average repeating number and represents a number of 0 to 10, h represents an integer of 1 to 3(preferably 2 to 3), j represents an integer of 1 to 3, i represents zero or an integer of 1 to 4, l is zero or integer of 1 to 3, and each of the R groups independently represents a bromine atom, a chlorine atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a hydrocarbon group having 6 to 20 carbon atoms, which includes a cycloalkyl group having 5 to 7 carbon atoms, or a group represented by the structural formula (3) described below:
wherein m represents a number of 0 to 9, and each of the R groups may be the same or different when i is 2 or more, Gly represents a glycidyl group, and A represents any one of an oxygen atom, a sulfur atom, or a group represented by the structural formulae (4) to (14) below:
wherein each of the T groups represents independently an alkyl group having 1 to 10 carbon atoms, and k is zero or an integer of 1 to 4; and further epoxy resins represented by the structural formulae (15) and (16) described below,
wherein h, j and n are as defined above, and B represents any one of the structural formula (4) as described above or the structural formula (17) below,
(wherein each of the U groups independently represents a halogen atom or an alkyl group having 1 to 10 carbon atoms, and T and i are as defined above)].
Examples of the epoxy resin represented by the above-mentioned structural formula (1) or (2) include difunctional epoxy resins derived from bisphenol A, tetrabromobisphenol A, bisphenol S, an alkyl-substituted dihydroxybiphenyl, dihydroxystilbene, an alkyl-substituted hydroquinone and the like; novolac type epoxy resins derived from a phenol novolac, a cresol novolac, a formaldehyde novolac of bisphenol A, a benzaldehyde novolac of phenol, an alkyl-substituted phenol, or the like; aralkyl type epoxy resins derived from phenol and terephthalaldehyde, an alkyl-substituted phenol and terephthalaldehyde, or the like; and epoxy resins derived f
Hayashi Toshiaki
Nakajima Nobuyuki
Fitch Even Tabin & Flannery
Lovering Richard D.
Sumitomo Chemical Company Ltd.
LandOfFree
Cyanate ester composition and cured product thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cyanate ester composition and cured product thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cyanate ester composition and cured product thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2896979