Adhesive bonding and miscellaneous chemical manufacture – Delaminating processes adapted for specified product – Delaminating in preparation for post processing recycling step
Patent
1991-02-26
1992-10-27
Kunemund, Robert
Adhesive bonding and miscellaneous chemical manufacture
Delaminating processes adapted for specified product
Delaminating in preparation for post processing recycling step
156DIG112, 429216, 423229, C30B 2960
Patent
active
051586436
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention generally relates to a method for manufacturing zinc oxide whiskers, and more particularly, to a method for manufacturing zinc oxide whiskers in uniform shape wherein each whisker is formed in a crystalline body composed of a core part and an acicular part extending not smaller than several tm long in four different directions from said core part (this structure of a whisker is hereinafter referred to as a specific shape).
At present, zinc oxide generally used as an industrial material is manufactured by a so-called French method in many cases. According to this French method, zinc oxide results in a dumpling aggregate of particles not uniform in size and particularly in shape. Although another method is known to produce zinc oxide in particles of slender and short aciculae with high yield (for example, disclosed in Japanese Patent Publication No. 60-5529 (5529/1985), this method is a revised version of the above French method, whereby steam of heated zinc is led outside a furnace and cooled rapidly, without achieving a huge crystalline body, but forming an acicular crystal of a very small size (0.1-15 tm long).
The acicular crystals obtained in the above-described prior arts are smaller in size by approximately two digits than various types of industrial whiskers presently in the market. Therefore, the prior art acicular crystals show no particular difference from the dumpling zinc oxide in terms of reinforcing effect for metals, ceramics, resins or the like. An outstanding reinforcing effect of whisker is not found in the prior art acicular particles. Meanwhile, a whisker consisting of a single crystal in fibrous structure has a remarkably high mechanical strength as compared with the dumpling substance of the same material, and accordingly drawing attention as a reinforcing material to obtain great mechanical strength in mixture with the other substance, and nowadays, various kinds of whiskers composed of, for example, metal, metal oxide, metal carbide, metal nitride, etc. are sold for industrial use. Moreover, although a whisker of zinc oxide having the length in mm digit is also known (Japanese Patent Laid-open Publication No. 50-5597 (5597/1975) which is the size of a simple acicula, the whisker disclosed in this prior art is manufactured from an alloy of zinc, and therefore impurities are included in the crystal, or a substrate is indispensable during the growth of the crystal at a position far from the material, with the other inconveniences being noted in the manufacture. That is, a complicated structure of the device for the manufacture, a long-time operation with low yield, etc. still remain to be solved. In other words, most of the prior art whiskers are within the range of experimental studies.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for manufacturing an aggregate of huge crystalline zinc oxide whiskers of the size suitable or larger for industrial use.
A further object of the present invention is to provide a method for manufacturing zinc oxide whiskers in a specific shape of the size necessary for industrial use, whereby 3-30 .mu.m zinc oxide whiskers and 30-250 .mu.m zinc oxide whiskers are selectively manufactured with high yield in a short time.
A still further object of the present invention is to provide a novel and simple method for manufacturing zinc oxide whiskers in a specific shape of the size necessary for industrial use with a small variation in distribution of the size, and more specifically, a novel manufacturing method of whiskers related to a baking process for evaporating metallic zinc, forming a core of crystal and growing the crystal.
A method for manufacturing zinc oxide whiskers according to one aspect of the present invention is characterized in that zinc powders coated with an oxide film on the surface thereof are heated in an atmosphere containing oxygen thereby to produce zinc oxide. It is a characteristic practice in the prior art vapor-phase manufacturing method like th
REFERENCES:
patent: 3844838 (1974-10-01), Louzos
patent: 3853625 (1974-12-01), Louzos
patent: 4487651 (1984-12-01), Wang
patent: 4722763 (1988-02-01), Pa et al.
Zinc Oxide Whiskers; Chiku et al.; Toyota Central Research and Development Laboratories, Inc. (1973) (1975).
Asakura Eizo
Kitano Motoi
Sato Takashige
Yagi Jun
Yoshida Hideyuki
Garrett Felisa
Kunemund Robert
Matsushita Electric - Industrial Co., Ltd.
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