Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Silicon dioxide – silicic acid – orthosilicate – or...
Reexamination Certificate
1999-10-06
2001-05-08
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Silicon dioxide, silicic acid, orthosilicate, or...
C508S136000, C508S547000, C072S042000
Reexamination Certificate
active
06228816
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an aqueous cutting agent, which can be used on precisely cutting/slicing work material made of a hard and brittle material such as an ingot of silicon single crystal or polycrystal, rock crystal, ceramic and glass, and an aqueous cutting liquid usable for the aqueous cutting agent, and a method for cutting the hard and brittle materials by using the aqueous cutting agent. More particularly, the present invention relates to an aqueous cutting agent, which is excellent in dispersion stability and viscosity stability of an abrasive grain and particularly effective for a wire sawing device, aqueous cutting liquid usable therefor, and a method for cutting/slicing hard and brittle materials, which is excellent in cutting performance, cleanability and the like of the work material.
BACKGROUND ART
Conventionally, in order to cut hard and brittle materials such as silicon single crystal, there has been used a cutting agent comprising an abrasive grain such as silicon carbide (SiC) dispersed in cutting liquid, and this cutting agent is supplied to a contact portion between a cutting device and work material to thereby obtain metal sheets of several tens to several thousands &mgr;m by slicing the work material thin.
Also, in the case of precision cutting using, for example, a multi-wire sawing device, the cutting is usually performed as follows: That is, in the multi-wire saw cutting device, wire is wound many times around a multi-grooved guide roller made of high molecular weight material, obtained by cutting with high precision to be reciprocated by a driving motor. This reciprocating wire is pressed against the work material while an adequate cutting load is being applied thereto to perform cutting by a cutting operation while the cutting agent is being supplied to the contact portion. Since the reciprocating wire is gradually worn as the work material is cut, the wire is wound up by a torque motor, and a new wire is supplied by a geared motor.
As the foregoing cutting agent, there have been used an oil cutting agent prepared by adding additives or the like to mineral oil as the base, a glycol cutting agent mainly composed of polyethylene glycol or polypropylene glycol, and an aqueous cutting agent mainly composed of an aqueous solution of a surface-active agent.
However, the conventional oil base cutting agents had the following problem: That is, the cutting agents mainly composed of mineral oil have the advantages that they are excellent in lubricating properties, and have good cut surface of the work material, and good cutting performance, but are inferior in cooling performance. Therefore, the conventional oil base cutting agents had the problem that the operating efficiency is decreased because the temperature at a contact portion increases during an operation to generate oil mist, an operator gets burned in a dismantling operation for the work material after the termination of a cutting operation, or a fire can also occur.
Also, when the work material, the operator and equipment have been contaminated by the cutting agents, an organic solvent cleaning fluid such as trichloroethane, methylene chloride or the like is required to remove the pollution. Since, however, the organic solvent cleaning fluid causes carcinogenesis or air pollution, there has also been the problem of waste treatment that it cannot be scrapped unless some disposal is performed for the cleaning discharge.
Also, in order to solve such conventional problems on the oil base cutting agent, the aqueous cutting agent mainly composed of the foregoing glycol cutting agent or aqueous solution of a surface-active agent has also been studied, but the viscosity stability during cutting was not sufficient, good cutting performance could not be obtained, and it was inferior in dispersion stability of the abrasive grain, and it could not be sufficiently satisfied.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide an aqueous cutting agent which is excellent in dispersion stability (properties in which the abrasive grain settle down and do not make any hard cake, but are easily re-dispersed by simple agitation) of the abrasive grain, re-dispersibility after settling, and viscosity stability during cutting/slicing operations, aqueous cutting liquid usable for the aqueous cutting agent, and a cutting/slicing method excellent in cutting performance, cooling performance, cleanability and the like of the work material on cutting/slicing hard and brittle material by using the cutting agent.
After earnestly studying to develop a cutting agent which solves the foregoing problems, the present inventors found out that the object could be achieved through an aqueous cutting agent comprising the abrasive grain dispersed in a specified aqueous solution of cationic water-soluble resin, and completed the present invention on the basis of these findings.
More specifically, the present invention provides an aqueous cutting liquid (first embodiment of the present invention) which comprises a cationic water-soluble resin having an amine value of 20 to 200 mgKOH/g, and at least one rheology control agent selected from the group consisting of an inorganic bentonite, an organic bentonite, and an aqueous silica sol, wherein the content of nonvolatile matter of the rheology control agent is 0.1 to 30 percent by weight of the amount of the nonvolatile matter of the cationic water-soluble resin.
Also, the present invention provides an aqueous cutting liquid (second embodiment of the present invention) which comprises a cationic water-soluble resin having a total amine value of 50 to 200 mgKOH/g, containing a tertiary amino group and a quaternary ammonium salt-containing group, and at least one rheology control agent selected from the group consisting of an inorganic bentonite, an organic bentonite and an aqueous silica sol, wherein the content of the nonvolatile matter of the rheology control agent is 0.1 to 30 percent by weight of the amount of the nonvolatile matter of the cationic water-soluble resin.
Also, the present invention provides an aqueous cutting liquid (third embodiment of the present invention) which comprises an aqueous silica sol with an average particle diameter of 100 nm or less, and a cationic water-soluble resin having a total amine value of 50 to 200 mgKOH/g, containing a tertiary amino group and a quaternary ammonium salt-containing group, wherein the content of the nonvolatile matter of the aqueous silica sol is 0.1 to 30 percent by weight of the amount of the nonvolatile matter of the cationic water-soluble resin.
Also, the present invention provides an aqueous cutting liquid (fourth embodiment of the present invention) in which the cationic water-soluble resin specified in the aqueous cutting liquid of the foregoing third embodiment of the present invention contains 20 to 80 percent by weight of the structural unit represented by the formula (1):
wherein R represents a hydrogen atom, a methyl group or an ethyl group.
Also, the present invention provides an aqueous cutting agent (fifth embodiment of the present invention) which comprises a cationic water-soluble resin having an amine value of 20 to 200 mgKOH/g and an abrasive grain, wherein the content of the abrasive grain is 100 to 1000 percent by weight of the amount of the nonvolatile matter of the cationic water-soluble resin.
Also, the present invention provides an aqueous cutting agent (sixth embodiment of the present invention) which comprises an aqueous cutting liquid specified in any one of the foregoing first to fourth embodiments according to the present invention and an abrasive grain, wherein the content of the abrasive grain is 100 to 1000 percent by weight of the amount of the nonvolatile matter of the aqueous cutting liquid.
Further, the present invention provides a method for cutting (seventh embodiment of the present invention) hard and brittle materials which comprises cutting the hard and brittle material with a cutting device by using the foregoing aqueous cutting agent.
REFERE
Hayashi Shigehiro
Ishidoya Masahiro
Ito Kenji
Maemichi Shunji
Mori Kazuyuki
Levy & Grandinetti
McAvoy Ellen M.
NOF Corporation
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