Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-04-13
2002-09-17
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...
52, C549S541000, C549S542000, C568S721000, C568S756000, C568S766000
Reexamination Certificate
active
06451879
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a phenolic resin having good hue or color tone and an epoxy resin that is derived from the phenolic resin, and processes for producing both the resins. The phenolic resin is prepared by reacting unsaturated cyclic hydrocarbon compounds such as dicyclopentadiene with hydroxylated aromatic compounds such as a phenolic compound.
More particularly, the invention relates to a phenolic resin and an epoxy resin, which are excellent in heat resistance, moisture resistance and crack resistance, so that they are useful as the resin materials for electrically insulating materials, especially for sealing or encapsulating semiconductors and for producing laminated materials. Furthermore, both the resins are so excellent in hue that they are useful as materials for molded products especially when the products are applied with marks.
BACKGROUND ART
Phenolic resins modified with dicyclopentadiene are produced using boron trifluoride or boron trifluoride-phenol complex as a catalyst. However, there is a problem that the resins are colored in dark brown so deeply that the external appearance of molded products is awfully disagreeable. The epoxy resin obtained by reacting the above phenolic resin with epihalohydrin in the presence of a base catalyst is similarly colored in dark brown because the phenolic resin as a starting material is colored. The resin composition for encapsulation prepared with the above epoxy resin has improved properties such as moisture resistance and heat resistance. However, it is troublesome to apply marks such as trade name, lot numbers and the like because the marks are recognized with difficulty, which seriously lowers the work efficiency.
In order to apply marks, a method using carbon dioxide laser or YAG laser is developed recently as well as the method using thermosetting ink or UV-setting ink. In the method of ink marking, printing ink is simply applied onto the surface of a resin. The method of laser marking is exemplified by the use of a thermal color former or the utilization of local vaporization phenomenon of surface with the laser heat. In the method of utilizing the local vaporization phenomenon of surface, carbon black is sometimes compounded into a sealing material (for example, Japanese Laid-Open Patent Publication No. H11-49936). In this case, it is not always required that the hue of sealing resin is good enough. However, in other methods such as the use of the above-mentioned thermal color former, it is usually preferable that the sealing resin is satisfactory in hue. That is, with preferable external appearance, an improved commercial value of product can be expected.
In order to improve the marking property, it is effective to use resins of generally yellow tinge by reducing the red tinge or black tinge as far as possible. For this reason, it has been demanded to propose a simple and easy process for producing yellowish phenolic resin that is modified with dicyclopentadiene.
For improving the hue, Japanese Laid-Open Patent Publication No. H08-53539 proposes a method in which the hue of a phenolic resin and thatof an epoxy resin obtained from the phenolic resin are improved by subjecting them to freeze drying or degassing several times. However, although this method can improve the hue of phenolic resin to a certain extent, there is a problem that a black tinge remains so that a further improvement is required as a starting material for epoxy resin. Moreover, because the above method needs process of freeze drying or degassing, the operation is complicated and requires much labor, so that the production cost is high.
In Japanese Laid-Open Patent Publication No. H07-252349, a method for improving hue is proposed, which comprises the steps of dissolving resins in an organic solvent and treating it with an inorganic porous substance. However, because the resins must be dissolved again in an organic solvent after refining by concentration, the operation is complicated and requires much labor, and the production cost is also high.
An object of the present invention is to provide a process for producing without difficulty a less colored phenolic resin satisfactory in hue by reacting a hydroxylated aromatic compound with an unsaturated cyclic hydrocarbon compound in the presence of an acid catalyst. Another object of the invention is to provide a process for producing a less colored epoxy resin satisfactory in hue similarly by reacting the phenolic resin obtained as above with an epihalohydrin in the presence of a base catalyst.
The present inventors have carried out extensive investigations in order to solve the above problems. As a result, they have found out that a phenolic resin satisfactory in hue can be obtained by reacting a hydroxylated aromatic compound with an unsaturated cyclic hydrocarbon compound in the presence of both active hydrogen and a metal compound with the aid of an acid catalyst. Furthermore, they have found out that an epoxy resin obtained by using the above phenolic resin is also excellent in hue. In view of these finding, the present invention has been accomplished.
Therefore, a first aspect of the present invention relates to a process for producing phenolic resin satisfactory in hue, that is characterized by the steps of reacting a hydroxylated aromatic compound with an unsaturated cyclic hydrocarbon compound in the presence of both active hydrogen and a reducing metal compound with the aid of an acid catalyst, subsequently deactivating the catalyst, and then removing the catalyst, the metal compound, and the unreacted hydroxylated aromatic compound.
A second aspect of the present invention relates to a process for producing a phenolic resin as described in the first aspect, wherein the acid catalyst is a Friedel-Crafts catalyst containing boron trifluoride.
A third aspect of the present invention relates to a process for producing a phenolic resin as described in the first aspect or in the second aspect, wherein the hydroxylated aromatic compound is monohydric phenol or dihydric phenol, and the unsaturated cyclic hydrocarbon compound is dicyclopentadiene.
A fourth aspect of the present invention relates to a process for producing an epoxy resin satisfactory in hue, that is characterized by the steps of reacting the phenolic resin obtained by a method as described in any of the first aspect to the third aspect with epihalohydrin with the aid of a base catalyst, and then removing the catalyst and the unreacted epihalohydrin.
A fifth aspect of the present invention relates to a phenolic resin satisfactory in hue obtained by the steps of reacting a hydroxylated aromatic compound with an unsaturated cyclic hydrocarbon compound with the aid of an acid catalyst, the resin having the absorbance of 0.5 or less at the wavelength of 350 nm and the absorbance of 0.1 or less at the wavelength of 430 nm in the measurement of absorptiometry in an ultraviolet-visible ray region using 2% solution of the refined resin in dioxane.
A sixth aspect of the present invention relates to an epoxy resin satisfactory in hue obtained by reacting a phenolic resin that is obtained by reacting a hydroxylated aromatic compound with an unsaturated cyclic hydrocarbon compound with the aid of an acid catalyst, with an epihalohydrin with the aid of a base catalyst, the epoxy resin having the absorbance of 0.5 or less at the wavelength of 350 nm and the absorbance of 0.1 or less at the wavelength of 430 nm in the measurement of absorptiometry in ultraviolet-visible ray region using 2% solution of the refined resin in dioxane.
By working a process as described in any of the first to fourth aspects, the phenolic resin or the epoxy resin satisfactory in hue as described in the fifth or sixth aspect can be obtained.
The phenolic resin and the epoxy resin obtained according to the present invention have little tinge of red or black in hue and high transparency by visual observation. Therefore, the appearance is excellent, so that the commercial value is high and the marking property is also satisfactory.
DISCLOSURE OF IN
Mori Satoshi
Oshimi Fumiaki
Ueno Ryuichi
Aylward D.
Hollander Law Firm, P.L.C.
Nippon Petrochemicals Company Limited
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