Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Reexamination Certificate
2002-09-06
2004-01-06
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
C508S136000, C508S143000, C508S154000, C508S506000, C508S512000, C072S042000
Reexamination Certificate
active
06673754
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of The Invention
The present invention relates to nonflammable water-based cutting fluid compositions and nonflammable water-based cutting fluids. More particularly, the present invention relates to water-based cutting fluids which are suitable for cutting process of single-crystal silicon and polycrystalline silicon that are crystal materials for semiconductors as well as ingots such as quartz, crystalline quartz, ceramics and the like, and to nonflammable water-based cutting fluids in a slurry state including the above water-based cutting fluids blended with abrasives. In addition, the present invention also relates to nonflammable water-based cutting fluid compositions and nonflammable water-based cutting fluids which are available in equipments for oil use.
2. Description of the Related Art
Conventionally, nonaqueous cutting fluids have been employed, which predominantly contain mineral oil in major proportions as a dispersion medium of abrasives in cutting fluids for use in cutting hard and brittle materials such as silicon ingots. This type of nonaqueous cutting fluids are in a slurry state in which abrasives such as silicon carbide is dispersed in cutting oil at a ratio of 1:1 on the basis of weight. This slurry is continuously supplied onto a surface subjected to cutting process. For the washes of the wafer which was thus cut out, cleaning liquids, e.g., a chlorinated organic solvent such as trichloroethane, methylene chloride and the like, and a nonionic surfactant with a high concentration have been used.
However, mineral oil is a dangerous substance having inflammability. Therefore, a facility equipped with an explosion-proof measure is required, restriction of quantity which can be stored is obliged, and problems can be caused involving in environmental conservation and manufacturing management. Furthermore, such cleaning liquids as chlorinated organic solvent described above for use in washing the wafer, which had been cut using mineral oil, may be a cause of cancer, problems involving in safety and health may be raised. Furthermore, these liquids have been recently prohibited because they may be main causes of air pollution and depletion of ozone layer. As an alternative washing solution of those, nonionic surfactant has been used, however, the nonionic surfactants necessitate a large scaled washing equipment due to their low washability, and moreover, problems in waste water treatment and disposal treatment have been raised because the surfactant must be used at a high concentration.
On the other hand, there have been proposed water soluble cutting fluids of water soluble glycol type which predominantly contains water soluble ethers of polyoxyalkylene glycol and derivatives thereof (see, JP-A-3-181598 and JP-A-11-198016) as a cutting fluid which allows washing with water after the cutting process.
However, the water soluble cutting fluids of glycol type necessitate the blending of water for disappearance of a flash point, and thus there arise problems in the manufacture and control thereof, e.g., lowered content of water results in the appearance of flash point; and blending water in a higher amount results in the deteriorated dispersion property of abrasives. In addition, even though the water soluble cutting fluids of glycol type can be readily washed with water, it is accompanied by higher loading of waste water, and problems have still remained in waste water treatment. Furthermore, when water soluble cutting fluids are introduced in the conventional equipments in which mineral oil-based cutting fluids were used, rust gathers, and therefore, investments have been required for e.g., improvement of the equipment and introduction of a dedicated equipment.
SUMMARY OF THE INVENTION
The present invention was accomplished taking into account of these conventional problems, and enables to provide nonflammable water-based cutting fluid compositions and nonflammable water-based cutting fluids which are excellent in dispersion property of abrasives also in a composition blended with a large amount of water, which are not accompanied by problems of flammability also for use in cutting process of hard and brittle materials, and which can be readily washed with water and satisfactory in waste water treatment property, through the use of a specified polycarboxylic acid-based polymer compound. In addition, to provide nonflammable water-based cutting fluid compositions and nonflammable water-based cutting fluids was allowed, which can exert rust preventive effects even if they are used in an equipment for oil use through the use of a specified carboxylic acid and/or a salt thereof.
Specifically, the nonflammable water-based cutting fluid composition according to the present invention is characterized in that it contains 5-45% by weight of a polycarboxylic acid-based polymer and/or a salt thereof compound having a weight-average molecular weight of 1,000-200,000.
The polycarboxylic acid-based polymer compound is believed to adsorb the abrasives, thereby exerting a stable dispersion effect through a protective colloid effect. Further, much greater dispersion property is achieved by the generation of electrostatic repulsive force due to ionicity imparted to a salt of a polycarboxylic acid-based polymer compound.
When the molecular weight of this polycarboxylic acid-based polymer compound is lower than 1,000, uniform protective colloid layer is not formed on the surface of the grains, and thus repulsive force among the grains are weakened. Accordingly, dispersion property and redispersion property are believed to be deteriorated. Further, when the molecular weight is greater than 200,000, agglomeration arises, and which may result in lowering of redispersion property.
The polycarboxylic acid-based polymer compound and/or a salt thereof described above is preferably selected from the group consisting of: a polymer prepared from one or more monomers selected from the group consisting of acrylic acid, maleic acid and methacrylic acid; an alkaline metal salt of said polymer; an onium salt of said polymer; and a mixture of one or more of the same.
Further, the polycarboxylic acid-based polymer compound and/or a salt thereof described above is preferably a polymer represented by the general formula (1).
In the general formula (1), R represents a hydrogen atom or a methyl group, M1, M2, and M3 are any one of a hydrogen atom, an alkaline metal atom or onium, which may be the same or different each other. The symbol n is an integer equal to or greater than 1, and m is an integer equal to or greater than 0.
The nonflammable water-based cutting fluid composition according to the present invention may further contain at least one additive auxiliary agent selected from the group consisting of a water soluble solvent, a lubricant, a viscosity adjusting agent, anti-corrosive agent for nonferrous metals and antifoaming agent. Among those, one or more water soluble solvents selected from polyoxyalkylene glycol or derivatives thereof are preferably contained as the additive auxiliary agent.
In addition, the nonflammable water-based cutting fluid composition according to the present invention may contain the carboxylic acid and/or a salt thereof described above at 0.05-5% by weight. The carboxylic acid and a salt thereof is added for enhancing the rust preventive function.
The carboxylic acid and/or a salt thereof is preferably selected from the group consisting of aliphatic dicarboxylic acids represented by the general formula (2), alkaline metal salts of said aliphatic dicarboxylic acids and onium salts of said aliphatic dicarboxylic acids. In the general formula (2), k is an integer of 6-12.
The nonflammable water-based cutting fluid according to the present invention is characterized in that it contains the above-described nonflammable water-based cutting fluid composition and abrasives.
In this fluid, the grain diameter of the above-descried abrasives is preferably 0.5-50 &mgr;m. Further, a cutting fluid including the nonflammable water-based cutting flui
Nabeshima Toshikazu
Shinike Hitoshi
Sugiyama Kaori
Dai-Ichi Kogyo Seiyaku Co. Ltd.
Marshall & Gerstein & Borun LLP
McAvoy Ellen M.
LandOfFree
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