Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-08-10
2002-06-18
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C528S205000, C549S517000, C549S518000, C549S541000, C549S542000, C568S721000, C568S756000, C568S766000
Reexamination Certificate
active
06407150
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a process for producing phenol resin and epoxy resin, which are excellent in color tone and which are derived from unsaturated cyclic hydrocarbon such as dicyclopentadiene together with phenol.
More particularly, the invention relates to a process for producing phenol resin and epoxy resin which are excellent in the resistance to heat, moisture and cracking or the like, so that they are useful as electrically insulating materials, particularly as resins for sealing or encapsulating semiconductors and resins for laminated plates. Furthermore, both the resins are excellent in external appearance and in marking property owing to their good color tone or color density (hereinafter sometimes referred to as simply “color”).
(2) Prior Art
In recent years, with the rapid progress in scientific technology, especially in electronic industry, requirements for properties of several products and their raw materials becomes gradually severer. Among them, the improvement in semiconductor technology is remarkable. With the progress in complexity of semiconductor memory, electronic circuits become minute and chip sizes become large. Moreover, mounting method is shifted from through-hole mounting to surface mounting. However, in automation lines of surface mounting, several troubles take place. For example, when a lead wires are soldered, semiconductor packages suffer from rapid change of temperature, which causes cracking in molded resin parts for sealing semiconductors, and interfaces among lead wires and resin are damaged to cause deterioration of moisture-proofing property.
In order to prevent the moisture-proofing property from deterioration, a method to increase the amount of filler by changing its particle shape is proposed. However, with this method, elasticity of resin increases, so that the resin is liable to suffer cracking due to thermal shock. Therefore, in order to reduce the thermal shock in semiconductor package when it is immersed in a solder bath, methods of modifying resin composition are proposed, such as the addition of silicone compounds or thermoplastic oligomer into the resin, or modification with silicone. However, in all of these methods, molded products suffer cracking after they are immersed into a solder bath, so that reliable resin compositions for sealing semiconductor cannot still be obtained.
In resin compositions for sealing semiconductor, those used as hardening agents are phenol resins such as phenolic novolak resin and cresol novolak resin, and the one used as a main component is epoxy resin having cresol novolak structure. However, when these resins are used, moisture-proofing property of semiconductor package is impaired to cause inevitably the above-mentioned cracking during immersion in a solder bath.
In recent years, therefore, in order to improve the thermal resistance of resin composition for use in sealing semiconductor, investigations have been conducted for improving phenol resins as raw materials of epoxy resins and their hardening agents. In Japanese Patent Application No. H03-66919, the present inventors proposed a phenol resin obtained by reacting phenol and an unsaturated polycyclic hydrocarbon compound having two or more carbon-carbon double bonds such as dicyclopentadiene, and they reported that the phenol resin can solve the above problem when it is used as a raw material of epoxy resin and its hardening agent.
It is widely known that the phenol resin modified with dicyclopentadiene can be produced with the use of boron trifluoride or boron trifluoride-phenol complex. However, it has been regarded as a problem that the phenol resins produced by this method are colored into dark brown so deeply that the external appearance of molded products are very poor, and the epoxy resin obtained by reacting the above resin with epihalohydrin is similarly colored into dark brown. When the epoxy resin is used as a raw material of sealing resin compositions, characteristics such as moisture-proofing property and thermal resistance can be improved. But on the other hand, there has been a problem in that the marking property of the compositions is so poor that operating efficiency is remarkably lowered in the process for production.
In Japanese Laid-Open Patent Publication No. H08-53539, a producing method with improving colors of epoxy resins is disclosed. However, the colors are still not satisfactory. Furthermore, this method has problems in that it requires freeze-drying in several times and degassing of raw materials, so that the operating process is complicated and it requires much labor, and in addition, the cost for production is high.
Further, in Japanese Laid-Open Patent Publication No. H07-252349, a method is presented for improving colors of resins by dissolving refined resins in a solvent and then contacting them with inorganic porous materials. However, there is a similar problem that the operating process is complicated and requires much labor, and production cost is expensive.
It is, therefore, the primary object of the present invention is to propose a method for producing phenol resin having desirable color tone by reacting hydroxyl group-containing aromatic compound and unsaturated cyclic hydrocarbon in the presence of an acid catalyst. Another object of the invention is to provide a method for producing epoxy resin that is excellent in color tone by using the above phenol resin.
BRIEF SUMMARY OF THE INVENTION
The present inventors have carried out investigation to solve the above problems, as a result, they have found out the following fact in the method for producing phenol resin by reacting hydroxyl group-containing aromatic compound with unsaturated cyclic hydrocarbon in the presence of Friedel-Crafts acid catalyst. That is, phenol resin having good color tone can be obtained by adjusting the moisture content in a reaction system during reaction, and in addition by adjusting the concentration of Friedel-Crafts catalyst. Furthermore, epoxy resin having good color tone can be obtained by adding glycidyl group to the obtained phenol resin in the presence of base catalyst, removing residual catalyst and refining by distilling off unreacted epihalohydrin. As a result, they have accomplished the present invention.
Thus, a first aspect of the present invention is a process for producing a phenol resin having good color tone, which process comprises reacting hydroxyl group-containing aromatic compound and unsaturated cyclic hydrocarbon under the conditions that the moisture is 100 ppm or less and the concentration of Friedel-Crafts catalyst is 0.07 mass % or less in a reaction system.
A second aspect of the present invention is a process for producing a phenol resin described in the first aspect, wherein a hydroxyl group-containing aromatic compound is the one selected from a group consisting of monohydric and dihydric phenols and bisphenol, and an unsaturated cyclic hydrocarbon is dicyclopentadiene.
A third aspect of the present invention is a process for producing a phenol resin described in the first aspect, wherein Friedel-Crafts catalyst is boron trifluoride.
A fourth aspect of the present invention is a process for producing epoxy resin having good color tone, which process comprises reacting the phenol resin described in a first aspect and epihalohydrin in the presence of base catalyst, then removing catalyst residue and removing unreacted epihalohydrin.
The phenol resin obtained in the first aspect of the present invention gives absorbance of 1.0 or lower at wavelength of 350 nm in a dioxane solution of 2 mass %, and the color tone is good.
In other words, it is possible to obtain a phenol resin that gives absorbance of 1.0 or lower at wavelength of 350 nm in a dioxane solution of 2 mass % by the present method. It comprises reacting hydroxyl group-containing aromatic compound and unsaturated cyclic hydrocarbon having two or more carbon-carbon double bonds in the presence of Friedel-Crafts catalyst.
Furthermore, an epoxy resin obtained according t
Hattori Masato
Mori Satoshi
Oshimi Fumiaki
Aylward D.
Dawson Robert
Hollander Law Firm, P.L.C.
Nippon Petrochemicals Company Limited
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