JP2017119781A - Dispersion liquid for loose abrasive grains - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dispersion liquid for loose abrasive grains, capable of suppressing thickening of a slurry during cutting of a silicon ingot.SOLUTION: The dispersion liquid for loose abrasive grains according to the present invention contains: 30 to 60 mass% (inclusive) of a lipophilic liquid whose solubility in water at 25°C is less than 5.0 mass%; 10 to 30 mass% (inclusive) of a hydrophilic liquid whose solubility in water at 25°C is 50 mass% or more; 0.01 to 5 mass% (inclusive) of a polymer dispersant having ionicity; and water. The content of the water is preferably 20 to 50 mass% (inclusive). The dispersion liquid for loose abrasive grains according to the present invention preferably further contains at least one surfactant selected from anionic surfactants and nonionic surfactants having a cloud point of 65°C or higher.SELECTED DRAWING: None

Description

  The present invention relates to a dispersion for free abrasive grains used in cutting, grinding, polishing, and cutting, a slurry containing free abrasive prepared using the dispersion for free abrasive grains, and a slurry containing free abrasive grains The present invention relates to a method for cutting a silicon ingot, a method for treating a slurry containing free abrasive grains, and a method for regenerating a dispersion for free abrasive grains.

  When cutting, grinding, polishing or cutting so-called brittle materials such as silicon, quartz, crystal, compound semiconductors, ceramics, glass, metal oxides, cemented carbide, sintered alloys, etc., abrasive grains are often used. A slurry containing free abrasive dispersed in a dispersion for free abrasive is used. At the time of processing, the slurry is supplied as a cutting fluid to the blade portion of the processing apparatus, and the operation is performed.

  Many of the water-soluble dispersions for free abrasive grains that are generally marketed are based on hydrophilic glycols as base oils, and are mainly designed by adding additives for mixing and dispersing abrasive grains. For example, Patent Documents 1 and 2 disclose water-glycol dispersions as dispersions for free abrasive grains.

  In recent years, attempts have been made to facilitate the disposal of used cutting oil compositions from the viewpoint of environmental friendliness and economic efficiency. In addition, from the viewpoint of improving environmental performance, productivity and economy, it has been attempted to reuse the used cutting oil composition. For example, Patent Document 3 discloses that a cutting oil composition is separated from a dispersion such as abrasive grains or ingot cutting powder and a cutting oil composition by centrifugation, and the cutting oil composition is reused. However, by repeating the reuse only by centrifugation, small abrasive grains, ingot cutting powder, and the like are accumulated in the cutting oil composition. There is a method of refining the cutting oil composition by distillation as a method of completely removing abrasive grains and cutting powder of ingots, but it is uneconomical because it uses a lot of energy. On the other hand, Patent Document 4 and Patent Document 5 disclose a fixed abrasive wire saw as a method for easily separating a dispersion such as abrasive grains and cutting powder of an ingot from cutting waste liquid with high separation efficiency by oil-water separation using a cloud point. A cutting fluid composition is disclosed.

JP-A-10-81872 Japanese Patent Laid-Open No. 10-324889 JP 2003-340719 A JP 2014-129495 A JP, 2015-127363, A

  However, when the cutting fluid composition for fixed abrasive wire saws is used as a dispersion for free abrasive grains, since there are many dispersions such as abrasive grains and cutting powders of ingots, the viscosity of the slurry is increased, resulting in poor cutting. It becomes possible. Further, when the free abrasive dispersion is a water-glycol dispersion, the ingot can be cut, but only a regeneration method using centrifugation can be used.

  Accordingly, the present invention provides a dispersion for free abrasive grains, which can suppress the thickening of the slurry during cutting of the ingot and can recover the constituents of the dispersion for free abrasive grains by a simple operation. The present invention provides a free abrasive-containing slurry containing an abrasive dispersion, a silicon ingot cutting method using the free abrasive-containing slurry, a method for treating a free abrasive-containing slurry, and a method for regenerating a free abrasive dispersion.

An example of the dispersion for free abrasive grains of the present invention is:
30 wt% or more and 60 wt% or less of a lipophilic liquid having a solubility in water of 25 ° C of 5.0 wt% or less,
A hydrophilic liquid having a solubility in water at 25 ° C. of 50% by mass or more and 10% by mass to 30% by mass;
0.01% by mass or more and 5% by mass or less of an ionic polymer dispersant;
And a dispersion for free abrasive grains containing water.

  An example of the free abrasive-containing slurry of the present invention is a free abrasive-containing slurry containing the free abrasive dispersion and free abrasive of the present invention.

  One example of the silicon ingot cutting method of the present invention includes a step of cutting the silicon ingot with the wire while supplying the slurry containing the free abrasive grains of the present invention to the cutting site of the wire and the silicon ingot or the entire silicon ingot. This is an ingot cutting method.

An example of a method for treating the slurry containing free abrasive grains of the present invention is as follows:
A treatment liquid containing the free abrasive-containing slurry of the present invention used for cutting a silicon ingot and the cutting powder of the silicon ingot is left as a target for stationary or centrifugal separation, and is relatively heavy in the treatment liquid. Separating the particles into relatively light particles and recovering a light particle dispersion in which relatively light particles of the liquid to be treated are dispersed;
The recovered light particle dispersion is heated to a temperature higher than the cloud point of the dispersion for free abrasive contained in the slurry containing free abrasive, whereby an upper layer mainly composed of oil, water and free abrasive And a step of recovering the upper layer after separating into a lower layer mainly composed of grains and cutting powder.

  The method for regenerating the dispersion for free abrasive grains according to the present invention is a shortage component when the upper layer recovered by the processing method for the slurry containing free abrasive grains according to the present invention is based on the unused dispersion for free abrasive grains. A method for regenerating a dispersion for free abrasive grains, comprising a step of adding a part or all of the above.

  According to the present invention, it is possible to suppress the thickening of the slurry during the cutting of the silicon ingot, and it is possible to recover the constituents of the free abrasive dispersion by a simple operation. A free abrasive-containing slurry containing an abrasive dispersion, a silicon ingot cutting method using the free abrasive-containing slurry, a method for treating a free abrasive-containing slurry, and a method for regenerating a free abrasive dispersion can be provided.

  In the dispersion for free abrasive grains of the present invention, the lipophilic liquid (component A) having a solubility in water at 25 ° C. of 5.0% by mass or less and the solubility in water at 25 ° C. is 50% by mass or more. The hydrophilic liquid (component B) and the ionic polymer dispersant (hereinafter sometimes abbreviated as “polymer dispersant”) (component C) are each contained in a predetermined content. A free abrasive-containing slurry (hereinafter also referred to as “slurry”) obtained by mixing free abrasive grains with this is used for cutting a silicon ingot (hereinafter also referred to as “ingot”). For example, thickening of the slurry during cutting of the ingot can be suppressed.

  Further, in an example of the method for treating a slurry containing free abrasive grains of the present invention, a liquid to be treated containing slurry and cutting powder containing free abrasive grains and a dispersion for free abrasive grains used for cutting an ingot is statically treated. As an object to be placed or centrifuged, it is separated into relatively heavy particles and relatively light particles in the liquid to be treated. Relatively heavy particles are abrasive grains having a relatively large particle size among dispersions such as free abrasive grains and ingot cutting powder contained in the liquid to be treated. Is a small dispersion (hereinafter sometimes referred to as “fine powder”). Abrasive grains having a relatively large particle size can be reused.

  In one example of the slurry processing method of the present invention, since the dispersion for free abrasive grains having a cloud point in a predetermined temperature range is used for the preparation of the slurry, the relatively light particles recovered from the liquid to be processed are The dispersed liquid (light particle dispersion) is oil-water separated by being heated to a temperature higher than the cloud point. The upper layer of the light particle dispersion separated from oil and water contains an oil phase portion, and the lower layer (also referred to as a waste layer) contains the fine powder that could not be separated by standing or centrifugation. Therefore, if only the upper layer (oil phase part) is recovered from the light particle dispersion that has been separated into oil and water, and the insufficient component when used based on the unused dispersion for free abrasive grains is added to the oil phase part, The dispersion for free abrasive grains can be regenerated. In the present invention, the cloud point means a temperature at which the free abrasive dispersion of the present invention starts to become cloudy from a transparent state when heated at normal pressure while stirring.

  Thus, in one example of the slurry processing method of the present invention, even if the particle size of the fine powder contained in the light particle dispersion is small, the oil phase portion and the fine powder are separated by oil-water separation using a cloud point. Can be separated. Therefore, according to the present invention, the fine powder can be separated by a more economical and simple operation than the method of purification by distillation. Further, since the oil phase portion and the fine powder can be separated without using a centrifugal separator, it is possible to suppress the blades inside the centrifugal separator from being scraped and deteriorated by the fine powder.

[Free abrasive dispersion]
An example of the dispersion for free abrasive grains of the present invention may be abbreviated as a lipophilic liquid (component A), a hydrophilic liquid (component B), and an ionic polymer dispersant (hereinafter referred to as “dispersant”). .) (Component C) and water (component D).

(Lipophilic liquid (component A))
The solubility of the lipophilic liquid (component A) in water at 25 ° C. is 5.0% by mass or less, preferably 4.0% by mass or less, more preferably 3% from the viewpoint of improving oil-water separation. From the viewpoint of improving miscibility with Component B and Component D, it is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more. In the present invention, “solubility of lipophilic liquid (component A) in water at 25 ° C.” means water (component D) when it becomes cloudy when gradually added to water at 25 ° C. ) Is a mass ratio of the lipophilic liquid (component A) to the value obtained by the following formula.
Solubility (mass%) = [addition amount of lipophilic liquid (component A) / addition amount of water (component D)] × 100

Component A contained in an example of the dispersion for free abrasive grains of the present invention is preferably a compound represented by the following general formula (1) from the viewpoint that fine adjustment of the cloud point is easy.
_{^{R 1 -O- (CH 2 CHR 2}} O) m-R 3 (1)
However, in the general formula (1), R ¹ may contain a hydroxyl group and may be a hydrocarbon group having 3 to 20 carbon atoms, R ² may be hydrogen or a methyl group, and R ³ may contain hydrogen or a hydroxyl group. A hydrocarbon group having 3 to 20 carbon atoms, m is an average added mole number of CH ₂ CHR ² O, and is 0 to 6 inclusive.

The carbon number of R ¹ is preferably 3 or more, more preferably 4 or more, from the viewpoint that fine adjustment of the cloud point is easy. Moreover, from a viewpoint of the ease of viscosity adjustment of the dispersion liquid for free abrasive grains, it is preferably 16 or less, more preferably 12 or less.

From the viewpoint of availability, R ³ is preferably hydrogen or a hydrocarbon group having 3 to 6 carbon atoms, more preferably hydrogen or a hydrocarbon group having 3 to 5 carbon atoms, still more preferably hydrogen or It is a hydrocarbon group having 3 to 4 carbon atoms.

  m is preferably 1 or more, more preferably 2 or more from the viewpoint of improving miscibility with Component B and Component D, and preferably 5 or less from the viewpoint of ease of viscosity adjustment of the dispersion for free abrasive grains. More preferably, it is 4 or less.

  In one example of the dispersion for free abrasive grains of the present invention, the content of component A is 30% by mass or more, preferably 33% by mass or more, more preferably from the viewpoint of improving the recovery rate of the upper layer mainly composed of oil. Is 35% by mass or more, and is 60% by mass or less, preferably 55% by mass or less, more preferably 50% by mass or less, from the viewpoint of cost reduction and ease of cloud point adjustment.

  Component A contained in an example of the dispersion for free abrasive grains of the present invention may be one of the compounds represented by the general formula (1), or may be a mixture containing two or more. Good.

(Hydrophilic liquid (component B))
The solubility of the hydrophilic liquid (component B) in water at 25 ° C. is preferably as high as possible from the viewpoint of compatibilizing component A and component D, specifically, 50% by mass or more. , Preferably it is 60 mass% or more, More preferably, it is 80 mass% or more. In the present invention, “the solubility of the hydrophilic liquid (component B) in water at 25 ° C.” refers to the water (component D) that starts to become cloudy when gradually added to water at 25 ° C. ) Is the mass ratio of the lipophilic liquid (component B) to the value obtained by the following formula.
Solubility (mass%) = [addition amount of hydrophilic liquid (component B) / addition amount of water (component D)] × 100

Component B contained in an example of the dispersion for free abrasive grains of the present invention is preferably a compound represented by the following general formula (2) from the viewpoint that fine adjustment of the cloud point is easy.
_{^{R 4 -O- (CH 2 CHR 5}} O) n-H (2)
However, in the general formula (2), R ⁴ is a hydrocarbon group having 3 to 20 carbon atoms that may contain hydrogen or a hydroxyl group, R ⁵ is hydrogen or a methyl group, and n is an average of CH ₂ CHR ⁵ O. The added mole number, which is 1 or more and 20 or less.

The number of carbon atoms of R ⁴ is preferably 3 or more, more preferably 4 or more, from the viewpoint of satisfactorily compatibilizing component A and component D. Moreover, from a viewpoint of the ease of viscosity adjustment of the dispersion liquid for free abrasive grains, Preferably it is 16 or less, More preferably, 12 or less is preferable.

  n is preferably 2 or more, more preferably 3 or more, from the viewpoint of improving solubility in water, and preferably 20 or less, more preferably from the viewpoint of ease of viscosity adjustment of the dispersion for free abrasive grains. Is 10 or less, more preferably 5 or less.

  In one example of the dispersion for free abrasive grains of the present invention, the content of Component B is 10% by mass or more, preferably 15% by mass or more, more preferably from the viewpoint of compatibilizing Component A and Component D. Is 20% by mass or more, and is 30% by mass or less, preferably 28% by mass or less, more preferably 26% by mass or less, from the viewpoint of improving oil-water separation.

  Component B contained in an example of the dispersion for free abrasive grains of the present invention may be one of the compounds represented by the general formula (2), or may be a mixture containing two or more. Good.

  The mass ratio of component A and component B (component A / component B) contained in an example of the dispersion for free abrasive grains of the present invention is preferably 1.0 or more, more preferably from the viewpoint of improving oil / water separation. From the viewpoint of satisfactorily compatibilizing Component A and Component D, it is preferably 5.0 or less, more preferably 3.0 or less.

(Ionic polymer dispersant (component C))
The dispersion for free abrasive grains of the present invention contains an ionic polymer dispersant in order to prevent aggregation and gelation of free abrasive grains and silicon cutting powder contained in the slurry and to keep the slurry at an appropriate viscosity. . The proper viscosity (25 ° C.) of the slurry here is preferably 50 mPa · s or more, more preferably 80 mPa · s or more from the viewpoint of improving the surface quality of the silicon wafer, and the silicon wafer cut out from the ingot From the viewpoint of improving the detergency, it is preferably 500 mPa · s or less, more preferably 400 mPa · s or less. The slurry viscosity can be measured with a B-type viscometer (25 ° C.).

Component C contained in an example of the dispersion liquid for free abrasive grains of the present invention has the following general formulas (3), (4-a), from the viewpoint of improving its own solubility and dispersibility of abrasive grains and cutting powder. A homopolymer or copolymer including at least one selected from the structural units represented by (4-b) and (5) is preferable.

In the general formula (3), R ⁶ is hydrogen or a methyl group, and R ⁷ , R ⁸ , and R ⁹ are the same or different and each represents hydrogen, an ethyl group, or a methyl group. A represents oxygen or NH, and p represents a number of 1 or more and 3 or less. X ₁ ⁻ represents a monovalent counter anion with respect to a nitrogen atom having a positive charge. The counter anion is preferably nitrate ion, organic acid ion or halogen ion, more preferably chlorine ion.

In the above general formulas (4-a) and (4-b), R ¹⁰ and R ¹¹ are the same or different and represent hydrogen or a methyl group, and X ₂ ⁻ represents a monovalent counter anion with respect to a positively charged nitrogen atom. . The counter anion is preferably nitrate ion, sulfate ion, organic acid ion, or halogen ion, more preferably chlorine ion.

上記一般式（５）中、Ｒ¹²は水素、又はメチル基を表す。

In the general formula (5), R ¹² represents hydrogen or a methyl group.

  From an amino group, a primary amino group and a secondary amino group constituting a monomer which is a source of the structural unit represented by the general formula (3), (4-a), or (4-b) The selected at least one basic group may be neutralized after polymerization of the monomer to be cationic, and the monomer may be one in which the basic group has been previously neutralized. Also good. The carboxyl group of the monomer, which is a supply source of the structural unit represented by the general formula (5), is neutralized after the polymerization of the monomer, specifically when preparing a dispersion for free abrasive grains. It is preferable that it becomes ionic.

  Specific examples of the monomer constituting Component C include acryloyloxyethyltrimethylammonium chloride, methacryloyloxypropyldimethylethylammonium monoethyl sulfate, neutralized dimethylaminoethylacrylamide phosphate, diallyldimethylammonium chloride, acrylic acid, Methacrylic acid is mentioned.

  When component C contains one or more structural units represented by general formulas (3), (4-a), and (4-b), from the viewpoint of improving compatibility, the dispersant (component C) The mass ratio of the total amount of the structural units represented by the general formula (3), (4-a), or (4-b) to all the structural units is preferably 50% by mass or more, and the general formula (3 ), (4-a), or (4-b), the mass ratio of the total amount of the structural units represented by (4-b) is more preferably 80% by mass or more, and the structural unit represented by the general formula (3) The mass ratio is more preferably 100 mass% or the mass ratio of the structural unit represented by the general formula (4-a) or (4-b) is 100 mass%. Specific examples include polydiallyldimethylammonium chloride (trade name: Marquat 100) and polymethacryloyloxyethylammonium chloride (trade name: Kaosela 3000).

  When Component C is a copolymer containing one or more structural units represented by General Formulas (3), (4-a), and (4-b), General Formulas (3), (4-a), And a monomer that is a supply source of structural units other than the structural unit represented by (4-b) is, for example, methyl (meth) acrylate, methoxypolyethylene glycol methacrylate, lauryl (meta) from the viewpoint of improving compatibility. ) Acrylate is preferred.

  When Component C includes one or more structural units represented by General Formula (5), Component C is represented by General Formula (5) for all structural units of Component C from the viewpoint of improving compatibility. A copolymer having a constitutional unit mass ratio of 50% by mass or less is preferred, and a copolymer comprising a constitutional unit represented by the general formula (5) and a constitutional unit derived from a hydrophobic alkyl (meth) acrylate is more preferred. In particular, a copolymer composed of a structural unit represented by the general formula (5) and a structural unit derived from a hydrophobic alkyl (meth) acrylate is more preferable. The structural unit represented by the general formula (5) Further preferred is a copolymer comprising a structural unit derived from a functional alkyl (meth) acrylate. Preferable specific examples of the copolymer include (meth) acrylic acid / methoxypolyethylene glycol (meth) acrylate / lauryl (meth) acrylate copolymer from the viewpoint of improving the dispersibility of abrasive grains and silicon cutting powder.

  In the example of the dispersion for free abrasive grains of the present invention, the weight average molecular weight of component C is preferably 1000 or more, more preferably 3000 or more, and still more preferably, from the viewpoint of improving dispersibility of the free abrasive grains and the silicon cutting powder. From the viewpoint of suppressing cross-linking between loose abrasive grains and silicon cutting powder, it is preferably 1,000,000 or less, more preferably 500,000 or less, and even more preferably 300,000 or less. In addition, when the component C contains 1 or more types of structural units represented by General formula (5), the measuring method of a weight average molecular weight can be measured with the following method.

The weight average molecular weight of component C was measured by GPC (gel permeation chromatography) under the following conditions. The weight average molecular weight was calculated based on a calibration curve prepared in advance. The following standard samples were used for preparing the calibration curve.
Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)
Column: TSK α-M (manufactured by Tosoh Corporation) × 2 Column temperature: 40 ° C.
Detector: RI
Eluent: N, N-dimethylformamide solution with H ₃ PO ₄ (60 mmol / L) and LiBr (50 mmol / L) added Eluent flow rate: 1.0 mL / min
Sample concentration: 0.1% by mass (solid content)
Sample injection volume: 0.1 mL
Standard sample: monodisperse polystyrene (manufactured by Tosoh Corporation: molecular weight 5.26 × 10 ² , molecular weight 1.02 × 10 ⁵ , molecular weight 8.42 × 10 ⁶ ; Nishio Kogyo Co., Ltd .: molecular weight 4.0 × 10 ³ , molecular weight 3 0.0 × 10 ⁴ , molecular weight 9.0 × 10 ⁵ )

  In one example of the dispersion for free abrasive grains of the present invention, the content of component C is preferably 0.01% by mass or more, more preferably 0.05% by mass, from the viewpoint of improving dispersibility of the free abrasive grains and the cutting powder. % Or more, more preferably 0.1% by mass or more, and preferably 5% by mass or less, more preferably 4% by mass or less, and still more preferably 3% by mass from the viewpoint of solubility in the dispersion for free abrasive grains. It is as follows.

(Water (component D))
An example of the dispersion for free abrasive grains of the present invention contains water. Since the free abrasive dispersion contains water (component D), the free abrasive dispersion has a cloud point. Moreover, the dispersion liquid for free abrasive grains exhibits a cooling effect at the time of cutting with a wire saw.

  Although water (component D) should just be contained as the remainder except the components AC of the dispersion liquid for free abrasive grains, and the arbitrary component mentioned later, in the example of the dispersion liquid for free abrasive grains of this invention. The content of component D is preferably 50% by mass or less, more preferably 45% by mass or less, and still more preferably 40% by mass or less, from the viewpoint of reducing the amount of the lower layer when oil-water separation is performed. Moreover, from a viewpoint of cost reduction and the ease of cloud point adjustment, Preferably it is 20 mass% or more, More preferably, it is 22 mass% or more, More preferably, it is 25 mass% or more.

  For example, ultrapure water, pure water, ion-exchanged water, or distilled water can be used as water contained in an example of the dispersion for free abrasive grains of the present invention. Ultrapure water, pure water, or Ion exchange water is preferable, and ultrapure water is more preferably used. Pure water and ultrapure water can be obtained, for example, by passing tap water through activated carbon, subjecting it to ion exchange treatment, and further distilling it, irradiating it with a predetermined ultraviolet germicidal lamp as necessary, or passing it through a filter. Can do. For example, the electrical conductivity at 25 ° C. is often 1 μS / cm or less for pure water and 0.1 μS / cm or less for ultrapure water.

  The cloud point of the dispersion for free abrasive grains of the present invention is preferably 30 ° C or higher, more preferably 35 ° C or higher, from the viewpoint of storage stability of the dispersion for free abrasive grains. Further, from the viewpoint of reducing the amount of hydrogen generated during heating, it is preferably 60 ° C. or lower, more preferably 55 ° C. or lower, and further preferably 50 ° C. or lower. The cloud point of the dispersion for free abrasive grains can be adjusted by the structures of component A and component B, and the content ratio of component A, component B and component D. In addition, the cloud point of the dispersion | distribution liquid for free abrasive grains can be measured by the method as described in an Example.

  An example of the dispersion for free abrasive grains of the present invention may further contain an organic solvent, a thickener, an antifoaming agent, a surfactant (component E), a preservative, a pH adjuster and the like as optional components. . Specific examples of the organic solvent include monohydric or polyhydric alcohols having 1 to 4 carbon atoms, and more specifically, ethanol, ethylene glycol, propylene glycol, diethylene glycol, glycerin and the like. Examples of the thickener include polyethylene glycol, polypropylene glycol, hydroxyethyl cellulose, hydroxypropyl cellulose and the like. As the antifoaming agent, a commercially available antifoaming agent containing silicone, polyalkylene glycol or the like can be used. Specific examples of the antifoaming agent include SN deformer 470 (manufactured by San Nopco, polyether-based antifoaming agent).

(Surfactant (component E))
An example of the dispersion for free abrasive grains of the present invention is at least one surfactant selected from an anionic active agent and a nonionic active agent having a cloud point of 65 ° C. or higher from the viewpoint of improving the separation efficiency of cutting powder. (Component E) is included. The “separation efficiency” of the cutting powder means the “removal rate” of the cutting powder contained in the liquid to be processed.

  Examples of the anionic surfactant include sulfonic acid surfactants, sulfuric acid surfactants, carboxylic acid surfactants, phosphoric acid surfactants, and among these, polyoxyalkylene alkyl sulfates Alkyl sulfate, alkyl ether sulfate, alkyl benzene sulfonate and the like are preferable. These anionic active agents may be used alone or in combination of two or more. The counter ion is a cation, and examples thereof include alkali metal ions, ammonium ions, organic quaternary ammonium ions, etc., but from the viewpoint of easy availability and improved separation efficiency of cutting powder, sodium ions, potassium ions, and ammonium ions are included. preferable.

  Examples of the nonionic activator having a cloud point of 65 ° C. or higher include polyoxyethylene alkylaryl ethers, polyoxyethylene fatty acid esters, oxyethylene / oxypropylene block copolymers, etc. From the viewpoint of improving oil / water separation properties, polyoxyethylene alkylaryl ethers and polyoxyethylene fatty acid esters are preferred. Examples of polyoxyethylene alkylaryl ethers include polyoxyethylene nonylphenyl ether. Examples of polyoxyethylene fatty acid esters include polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol monooleate, and the like.

但し、前記一般式（６）中、ＥＯはエチレンオキシ基であり、ｑはエチレンオキシ基の平均付加モル数であり、ｑは１以上１５０以下であり、ｒはスチレン基の置換数であり、ｒは１以上３以下である。 Among these nonionic active agents having a cloud point of 65 ° C. or higher, a compound represented by the following general formula (6) having a low ability to emulsify component A is preferable.

However, in the said General formula (6), EO is an ethyleneoxy group, q is the average addition mole number of ethyleneoxy group, q is 1 or more and 150 or less, r is the substitution number of a styrene group, r is 1 or more and 3 or less.

  The average added mole number q is 1 or more from the viewpoint of improving the dispersibility of the cutting powder, but is preferably 10 or more, more preferably 30 or more, further preferably 40 or more, still more preferably 50 or more, and 60 or more. More preferably, from the viewpoint of improving the oil / water separation property of the cutting fluid composition, it is 150 or less, preferably 100 or less, more preferably 90 or less, still more preferably 80 or less, and even more preferably 70 or less.

  The substitution number r of styrene group is 1 or more and 3 or less from the viewpoint of improving the dispersibility of the cutting powder, but 2 is preferable, and the nonionic activator having a cloud point of 65 ° C. or more represented by the general formula (6) is preferable. Is preferably polyoxyethylene distyrenated phenyl ether.

  The content of the surfactant (component E) in the dispersion for the free abrasive is preferably 0.5% by mass or more, and 0.8% by mass from the viewpoint of improving the cutting performance of the wire saw and improving the separation efficiency of the cutting powder. The above is more preferable, and from the same viewpoint, 5.0% by mass or less is preferable, 4.0% by mass or less is more preferable, and 3.0% by mass or less is more preferable.

  The pH at 25 ° C. of the dispersion for free abrasive grains of the present invention is preferably 5.0 or more, more preferably 5.5 or more, still more preferably 6.0 or more, from the viewpoint of rust prevention of the apparatus. From the viewpoint of safety of a person, it is preferably 10.0 or less, more preferably 9.5 or less, and still more preferably 9.0 or less.

(Preparation method of dispersion for loose abrasive)
The method for preparing the dispersion for free abrasive grains can be prepared by mixing components A to D and optional components. From the viewpoint of improving the operability for preparing a dispersion for free abrasive grains, it is preferable to add component A to the mixture of component B and component D, and component C is added to the mixture of component A, component B and component D. It is preferred if When the dispersion for free abrasive grains contains a surfactant (component E) as an optional component, component E is preferably added to the mixture of component B and component D before addition of component A. When component E is a crystalline solid, it is preferable to add component E after adding component E to the mixture of component B and component D and then heating them to melt component E.

(Silicon ingot cutting method)
The dispersion for free abrasive grains of the present invention can be used in an ingot cutting method. An example of the ingot cutting method of the present invention includes a step of cutting an ingot using a slurry containing free abrasive grains and a dispersion for free abrasive grains.

  The ingot can be cut by moving the slurry at a high speed while supplying the slurry to the wire and the cutting portion of the ingot or the entire ingot and pressing the wire against the ingot.

  As the free abrasive grains, silicon carbide (SiC) abrasive grains are preferable. The abrasive grain size of the silicon carbide (SiC) abrasive is preferably 8 μm or more and 20 μm or less, more preferably 10 μm or more and 15 μm or less. For the measurement of the abrasive particle size, a laser diffraction / scattering particle size distribution analyzer LA-920 manufactured by Horiba, Ltd. can be used. Ion exchange water is used as a dispersion medium, and the relative refractive index is 2.0. The abrasive particle diameter is a volume average particle diameter (median diameter).

  The ratio of the dispersion for free abrasive grains in the slurry varies depending on the type of free abrasive grains and the abrasive particle diameter. For example, when silicon carbide (SiC) abrasive grains having an abrasive grain size of 10 μm or more and 15 μm or less are used as the free abrasive grains, the proportion of the dispersion for free abrasive grains in the slurry is preferably 40% by mass or more and 60% by mass or less. More preferably, it is 45 mass% or more and 55 mass%.

  A conventionally well-known apparatus can be used for the wire saw used for the cutting | disconnection of a silicon ingot. A conventionally well-known wire, for example, a piano wire, can be used also about a wire.

  The wires are supplied from, for example, a wire saw supply reel, and are wound and arranged in grooves with a predetermined interval provided on the main roller. The wire can be moved and moved by rotating the main roller at a predetermined rotation speed, and is usually moved and moved at a high speed so as to be about 400 m / min to 1000 m / min. The wire saw may be a single type that performs cutting with a single wire.

  The slurry can be prepared by a conventionally known method. For example, after mixing the free abrasive grains and the dispersion liquid for free abrasive grains, it can be carried out by preferably stirring for 5 hours or more.

(Treatment of slurry containing free abrasive grains)
An example of the treatment of the free abrasive-containing slurry of the present invention is the treatment of the free abrasive-containing slurry used for cutting the ingot with a wire using the free abrasive. An example of the treatment of the free abrasive-containing slurry of the present invention is to statically treat the liquid to be treated containing the slurry used for cutting the ingot containing the free abrasive and the free abrasive dispersion and the cutting powder of the silicon ingot. Obtained by the first step and the first step of separating the light particle dispersion into the liquid to be treated, which is separated into relatively heavy particles and relatively light particles in the liquid to be treated. The step of recovering the upper layer by heating the light particle dispersion to separate the upper layer mainly composed of oil and the lower layer mainly composed of water, the free abrasive grains, and the cutting powder of the silicon ingot. And including. In an example of the treatment of the free abrasive-containing slurry of the present invention, oil-water separation is performed by heating the light particle dispersion to a temperature higher than the cloud point of the free abrasive dispersion.

  Since an example of the processing method of the slurry containing the free abrasive grains of the present invention collects the constituent components of the abrasive dispersion liquid, it can also be referred to as “abrasive dispersion component recovery method”.

(First step)
In the first step, the liquid to be treated is allowed to stand or be centrifuged, so that the liquid to be treated is separated into relatively heavy particles and relatively light particles, and the light particle dispersion is recovered. . In the following, the remaining part of the light particle dispersion recovered from the liquid to be treated is referred to as “heavy particle-containing liquid”. This heavy particle-containing liquid is a slurry containing a high concentration of reusable abrasive grains.

  From the viewpoint of improving the reusability of abrasive grains, the heavy particle-containing liquid preferably contains 80% by mass or more, more preferably 90% by mass or more, of the cutting powder and free abrasive grains contained in the liquid to be treated. From the viewpoint of improving the quality of the slurry after reuse, the content is preferably 98% by mass or less, more preferably 96% by mass or less, of the cutting powder and free abrasive grains contained in the liquid to be treated.

  In the light particle dispersion, from the viewpoint of recoverability of the free abrasive dispersion, the free abrasive dispersion used in the preparation of the slurry is preferably 60% by mass or more, more preferably 70% by mass. The above is included.

  The particle diameter of the free abrasive grains contained in the heavy particle-containing liquid is preferably 8 μm or more, more preferably 9 μm or more, from the viewpoint of machinability when reused. The abrasive particle diameter is a volume average particle diameter (median diameter).

  The particle size of the fine powder contained in the light particle dispersion is about 2 μm or less.

  When the liquid to be treated is separated into relatively heavy particles and relatively light particles by standing, the standing time is preferably 8 hours or more from the viewpoint of the abrasive particle diameter contained in the heavy particle-containing liquid. More preferably, it is 12 hours or more, and from the viewpoint of cycle time, it is preferably 36 hours or less, more preferably 24 hours or less.

  When the liquid to be treated is to be centrifuged, the centrifugal force G (gravity acceleration) is preferably 100 G or more from the viewpoint of recovering reusable abrasive grains with a high yield (for example, about 90% by mass). From the viewpoint of suppressing the mixing amount of the cutting powder, it is preferably 3000 G or less. Also, from the viewpoint of recovering recyclable abrasive grains in a high yield, do not stop the rotation, but gradually reduce the speed so that no sudden load is applied to the separation and movement of each component in the liquid. Is desirable.

  Examples of the method for recovering the light particle dispersion include decantation and filtration.

  When the pH of the liquid to be treated is outside the range of 5.0 or more and 10.0 or less, the liquid to be treated is subjected to standing or centrifugation from the viewpoint of easily separating the cutting powder from the liquid to be treated with high separation efficiency. Before adjusting the pH of the liquid to be treated, it is preferable to adjust the pH within the range of 5.0 or more and 10.0 or less, and preferably 6.0 or more from the viewpoint of improving the separation efficiency of the cutting powder and suppressing corrosion of the apparatus. 7.0 or more is more preferable.

  The pH of the liquid to be treated can be adjusted using a pH adjuster. The pH adjusting agent may be the same as the pH adjusting agent used for preparing the dispersion for free abrasive grains.

(Second step)
In the second step, the cloud phase is used to separate and recover the oil phase portion from the light particle dispersion. Specifically, the light particle dispersion obtained in the first step is heated to a temperature (separation operation temperature) equal to or higher than the cloud point of the dispersion for free abrasive grains. Thereafter, when the light particle dispersion is left standing or weakly stirred while maintaining the separation operation temperature, the light particle dispersion is divided into an upper layer mainly composed of component A and a lower layer mainly composed of water and fine powder. To separate. In order to separate the light particle dispersion into the upper layer and the lower layer, for example, the separation operation temperature may be maintained for 1 hour. After the light particle dispersion is separated, the state of separation is maintained even if the temperature is not higher than the separation operation temperature unless well stirred.

  “Containing component A as the main component” means that the content of component A in the upper layer is larger than any other component that can be contained in the upper layer, and “main component is water and fine powder. "" Means that the sum of the water content and the fine powder content in the lower layer is greater than that of any of the other components that may be included in the lower layer. In addition to component A, the upper layer may contain a part of component B and a small amount of water (component D), and may further include a component that is hardly soluble in water among the optional components contained in the dispersion for free abrasive grains. is there. The fine powder is hardly contained, and preferably at least the fine powder is not contained. On the other hand, in the lower layer, in addition to water (component C) and fine powder, a part of component B is included, and among the optional components included in the dispersion for free abrasive grains of the present invention, a component that is easily soluble in water is further included. And component A may be included in a small amount.

  The separation operation temperature is preferably 5 to 50 ° C. higher than the cloud point of the dispersion for free abrasive grains, more preferably 7 to 7 from the viewpoint of improving the separation efficiency of the fine powder and reducing the amount of energy used. The temperature is 40 ° C higher, more preferably 10-30 ° C higher. From the viewpoint of improving the separation efficiency of the fine powder, the light particle dispersion is preferably stirred before and / or during heating.

  As a method for recovering the upper layer from the light particle dispersion, for example, the upper layer may be extracted by a pump, or may be recovered after removing the lower layer. From the viewpoint of improving the quality of the regenerated dispersion for free abrasive grains, not only the lower layer but also a part of the upper layer adjacent to the lower layer may be removed from the light particle dispersion.

  If the total mass of the components of the dispersion for free abrasive used in the preparation of the slurry is 100% by mass, the dispersion for free abrasive used in the preparation of the slurry by recovering the upper layer from the light particle dispersion Of these, preferably 50% by mass or more, more preferably 60% by mass or more can be recovered.

(Regeneration method of dispersion for loose abrasive)
In the method for regenerating a dispersion for free abrasive grains according to the present invention, an insufficient component based on an unused dispersion for free abrasive grains is added to the upper layer recovered by the slurry processing method. For example, in the recovered upper layer, the concentration of component A is 30% by mass to 60% by mass, the concentration of component B is 10% by mass to 30% by mass, and the concentration of component C is 0.01% by mass to 5% by mass In addition, at least one of component A, component B, component C and component D is added as necessary so that the concentration of component D is 20% by mass or more and 50% by mass or less, and further, if necessary. The said arbitrary component is added and the dispersion liquid for free abrasive grains is obtained. If this is mixed with abrasive grains, a reusable slurry can be prepared.

  The addition amount of at least one component selected from the group consisting of components A to D to the upper layer is preferably determined based on the measurement results by measuring the content of components A to D in the upper layer. . Or the reduction | decrease of components AD accompanying the recovery process of the cutting process which cut | disconnects an ingot with a wire using the slurry containing the dispersion liquid for free abrasive grains, and a free abrasive grain, and the dispersion liquid for free abrasive grains etc. The amount may be estimated in advance, and components A to D, etc., having the same amount as the amount of decrease may be supplied to the upper layer. For the measurement of the content of components A to D, for example, titration, NMR measurement, gas chromatography, liquid chromatography and the like can be used.

[Slurry viscosity evaluation method]
In general, the abrasive viscosity (silicon carbide) is pulverized during cutting to increase the surface area, thereby increasing the slurry viscosity. Therefore, as a model experiment, a slurry serving as a model after cutting was prepared by preparing pulverized abrasive grains and then mixing non-pulverized abrasive grains.
In a 500 mL wide-mouthed plastic bottle, weigh 24 g of silicon carbide abrasive grains (manufactured by Fujimi Incorporated, trade name GC # 1200) and 60 g of the dispersion for free abrasive grains, add 200 g of 2 mmφ zirconia beads and stir well. After heating to 60 ° C., the mixture was pulverized for about 2 hours with a paint shaker until the volume average particle size of the silicon carbide abrasive grains became 3 μm or less. After mixing 56 g of the obtained pulverized silicon carbide abrasive-containing slurry and 24 g of non-pulverized silicon carbide abrasive (product name: GC # 1200, manufactured by Fujimi Incorporated), and stirring well, a B-type viscometer The viscosity was measured at The rotor was No. 2, the rotational speed of the rotor was 60 rpm, and the temperature of the measurement object was 25 ° C.

  << Evaluation >> When the slurry viscosity exceeds 500 mPa · s, the abrasive grains are not sufficiently supplied to the cutting site, and thus a high-quality silicon wafer cannot be obtained. Therefore, when the slurry viscosity exceeds 500 mPa · s, it was determined to be rejected.

[Oil / water separation evaluation method]
In a 50 mL plastic bottle, 25 g of dispersion for free abrasive grains, 5.0 g of 5 μm silicon powder (manufactured by Kojundo Chemical Laboratory Co., Ltd.), silicon carbide powder (manufactured by Fujimi Incorporated, product name GC # 10000) 1.25 g was weighed, 50 g of 2 mmφ zirconia beads were added and stirred well, and pulverized with a paint shaker for 3 hours. After removing the zirconia beads, weigh 20g of the mixture of the free abrasive dispersion, silicon powder and silicon carbide powder into a 50mL clear plastic bottle (of which the free abrasive dispersion weight is 16g) and measure at 60 ° C. Left in a warm bath. The state of oil-water separation was observed after 1 hour, the upper layer (oil phase) was taken out, the weight was measured, and the recovery rate was calculated from the following formula.
Recovery rate (%) = weight of oil phase g / 16 g × 100

[Measurement of cloud point]
(Measurement of cloud point of dispersion for loose abrasive)
(1) Put 50 mL of the dispersion for free abrasive grains into a 100 mL capacity test tube.
(2) Put the test tube in a water bath, and manually stir the suspension dispersion for floating abrasives using a glass rod-shaped thermometer, and change the temperature of the dispersion for free abrasive grains from room temperature to a rate of 2 ° C / min. Raise it.
(3) When the turbidity does not disappear even after stirring, the temperature of the dispersion for free abrasive grains is read.
(4) Remove the test tube from the water bath and gradually lower the temperature to room temperature while stirring in an atmosphere at 25 ° C.
(5) (2) to (4) are repeated twice, and the average value of the temperatures read in (3) is taken as the cloud point of the dispersion for free abrasive grains.

(Measurement of cloud point of nonionic active agent)
(1) Deionized water is added to the sample so that the sample (nonionic activator) is 7% by weight, and 50 mL of the resulting aqueous sample solution is placed in a 100 mL test tube.
(2) The test tube is put in a water bath, and the temperature of the sample aqueous solution is increased from room temperature at a rate of 2 ° C./min while manually stirring the sample aqueous solution using a glass rod-shaped thermometer.
(3) When the turbidity does not disappear even after stirring, the temperature of the sample aqueous solution is read.
(4) Remove the test tube from the water bath and gradually lower the temperature of the aqueous sample solution to room temperature while stirring in an atmosphere of 25 ° C.
(5) Repeat (2) to (4) twice, and let the average value of the temperature of the sample aqueous solution read in (3) be the cloud point.

[Synthesis of Polymer Dispersant A]
Attach a condenser and thermometer to a 1L 4-neck separable flask and thoroughly purge with nitrogen, then 6.75g of lauryl methacrylate, methoxypolyethylene glycol (EO23 mol) methacrylate (made by Shin-Nakamura Chemical Co., Ltd., trade name: NK -TM230), 31.50 g, 6.75 g of methacrylic acid, 1.35 g of 3-mercapto-1,2-propanediol, and 27.0 g of ethanol were measured. The mixture was heated to 80 ° C. with stirring, and 1.35 g of V-65 (2,2′-Azobis (2,4-dimethylvaleronitrile)) dissolved in 11.25 g of ethanol was added thereto. Subsequently, 60.75 g of lauryl methacrylate, 283.50 g of methoxypolyethylene glycol (EO23 mol) methacrylate, 60.75 g of methacrylic acid, 12.15 g of 3-mercapto-1,2-propanediol, and 12.15 g of V-65 were uniformly dissolved in 243.0 g of ethanol. The resulting solution was added dropwise over 3 hours. Stirring was continued at 80 ° C. for 1 hour after the completion of dropping, and then cooled to room temperature, and then diluted by adding 100 g of ethanol. As confirmed by NMR, the conversion of lauryl methacrylate was 98%, the conversion of methoxypolyethylene glycol (EO23 mol) methacrylate was 99%, and the conversion of methacrylic acid was 97%. The obtained polymer dispersant A had a solid content concentration of 56%, and was measured by gel permeation chromatography. As a result, the weight average molecular weight in terms of polystyrene was 7,500.

[Example 1]
As component B, butyltriethylene glycol (manufactured by Nippon Emulsifier Co., Ltd., trade name BTG), and as component E, nonionic surfactant (trade name Emulgen A500, manufactured by Kao Corporation) and purified water are mixed, It heated to 60 degreeC and was set as the uniform transparent liquid. Next, after cooling the uniform transparent liquid to 40 ° C., the uniform transparent liquid, butyl dipropylene glycol (manufactured by Nippon Emulsifier Co., Ltd., trade name BFDG) and antifoaming agent (manufactured by San Nopco Co., Ltd.) as component A The product name SN deformer 470) was mixed and stirred well. Finally, as a component C, a cationic polymer (trade name Kaosela 3000, manufactured by Kao Corporation) was mixed and stirred until uniform, and neutralized with an appropriate amount of 10N aqueous KOH solution as a pH adjuster. A free abrasive dispersion 1 was obtained. The composition ratio of each component is as shown in Table 1, and KOH is negligible in calculating the content of each component because it is very small.

[Example 2]
A dispersion for free abrasive grains of Example 2 was prepared in the same procedure as Example 1 except that the composition ratio of each component was different and that no KOH aqueous solution was used.

[Example 3]
Dispersion for free abrasive grains of Example 3 in the same procedure as Example 1 except that the composition ratio of each component is different and diethylene glycol dibutyl ether (manufactured by Nippon Emulsifier Co., Ltd.) is further added as Component A. A liquid was prepared.

[Example 4]
Example 1 and Example 1 except that the composition ratio of each component is different and that diallyldimethylammonium chloride homopolymer (manufactured by Lubrizol, trade name: Marcoat (registered trademark) 100) is used as component C instead of Kaosela 3000. A free abrasive dispersion of Example 4 was prepared in the same procedure.

[Example 5]
Example 1 except that the composition ratio of each component is different and that the polymer dispersant A obtained by the method described in [Synthesis of Polymer Dispersant A] above is used as Component C instead of Caosela 3000. The dispersion for free abrasive grains of Example 5 was prepared by a simple procedure.

[Comparative Examples 1-4]
Dispersions for free abrasive grains of Comparative Examples 1 to 4 were prepared in the same procedure as in Example 1 except that the composition ratio of each component was different and that component C was not included. In Comparative Example 3 and Comparative Example 4, the amount of surfactant (component E) used was increased.

[Comparative Example 5]
Diethylene glycol and purified water were mixed at the composition ratio shown in Table 1, and stirred well to obtain a dispersion for free abrasive grains of Comparative Example 5.

[Evaluation 1]
Using the dispersions for free abrasive grains of Examples 1 to 5 and Comparative Examples 1 to 5, slurry was prepared according to the above “Slurry Viscosity Evaluation Method”, and the viscosity was measured. As shown in Table 1, except for Comparative Example 1, the increase in viscosity was suppressed to 300 mPa · s or less.

The details of the substances listed in Table 1 are as follows.
(Component A)
C4PO2: Butyldipropylene glycol (manufactured by Nippon Emulsifier Co., Ltd., trade name BFDG, solubility in water at 25 ° C. 3% by mass, R ¹ = C ₄ H ₉ , R ² = CH ₃ , R ³ = H, m = 2)
DBDG: Diethylene glycol dibutyl ether (manufactured by Nippon Emulsifier Co., Ltd., solubility in water at 25 ° C. 0.3 mass%, R ¹ = C ₄ H ₉ , R ² = H, R ³ = H, m = 2)
(Component B)
C4EO3: Butyltriethylene glycol (manufactured by Nippon Emulsifier Co., Ltd., trade name BTG, solubility in water at 25 ° C. of 100% by mass or more, R ⁴ = C ₄ H ₉ , R ₅ = H, n = 3)
EH · EO4: Tetraethylene glycol mono 2-ethylhexyl ether (manufactured by Nippon Emulsifier Co., Ltd., trade name Newcol (registered trademark) 1004, solubility in water at 25 ° C. of 100% by mass or more, R ⁴ = C ₈ H ₁₇ , R ₅ = H, n = 4)
(Component C)
Kaosela (registered trademark) 3000: polymethacryloyloxyethylammonium chloride (manufactured by Kao Corporation, weight average molecular weight 25,000)
Marcote 100: diallyldimethylammonium chloride homopolymer (manufactured by Lubrizol, weight average molecular weight 150,000)
Polymer dispersant A: methacrylic acid / methoxypolyethyleneglycol methacrylate / lauryl methacrylate copolymer (weight average molecular weight 7,500, mass ratio = 15/70/15)
(Defoamer)
DF470: Polyether-based antifoaming agent (manufactured by San Nopco, trade name: SN deformer 470)
(Surfactant (component E))
Emulgen (registered trademark) A-500: polyoxyethylene distyrenated phenyl ether (manufactured by Kao Corporation, distyrenated phenol group, average added mole number of oxyethylene units of polyoxyethylene: 50, cloud point of 100 ° C or higher)
Coatamine (registered trademark) D86P: distearyldimethylammonium chloride (manufactured by Kao Corporation)
Coatamine (registered trademark) D2345P: dilauryldimethylammonium chloride (manufactured by Kao Corporation)
Farmin (registered trademark) 20D: Laurylamine (manufactured by Kao Corporation)

[Evaluation 2]
Using the dispersions for free abrasive grains of Examples 1 to 3 and Comparative Examples 1 to 5, the recovery rate (%) was calculated according to the above [Oil / Water Separation Evaluation Method]. As shown in Table 2, oil-water separation is good in Examples 1 to 3 using an ionic polymer as the polymer dispersant, and the recovery rate of the constituent components (oil phase) of the dispersion for free abrasive grains is also good. Met.

  If the dispersion liquid for free abrasive grains of the present invention is used, thickening of the slurry during cutting of the ingot can be suppressed, which can contribute to extending the life of the wire saw and improving the smoothness of the cutting surface of the silicon wafer. Further, according to the method for regenerating a slurry of the present invention, oil / water separation can be satisfactorily performed by a simple operation, which can contribute to an increase in the number of recycles.

Claims (10)

30 wt% or more and 60 wt% or less of a lipophilic liquid having a solubility in water at 25 ° C of less than 5.0 wt%,
A hydrophilic liquid having a solubility in water at 25 ° C. of 50% by mass or more and 10% by mass to 30% by mass;
0.01% by mass or more and 5% by mass or less of an ionic polymer dispersant;
And a dispersion for free abrasive grains.   The dispersion for free abrasive grains according to claim 1, wherein the water content is 20 mass% or more and 50 mass% or less. The dispersion for free abrasive grains according to claim 1 or 2, wherein the lipophilic liquid is a compound represented by the following general formula (1).
_{^{R 1 -O- (CH 2 CHR 2}} O) m-R 3 (1)
However, in the general formula (1), R ¹ may contain a hydroxyl group and may be a hydrocarbon group having 3 to 20 carbon atoms, R ² may be hydrogen or a methyl group, and R ³ may contain hydrogen or a hydroxyl group. A hydrocarbon group having 3 or more and 20 or less carbon atoms, m is an average added mole number of CH ₂ CHR ² O, and represents a number of 0 or more and 5 or less. The dispersion for free abrasive grains according to any one of claims 1 to 3, wherein the hydrophilic liquid is a compound represented by the following general formula (2).
_{^{R 4 -O- (CH 2 CHR 5}} O) n-H (2)
However, in the general formula (2), R ⁴ is a hydrocarbon group having 3 to 20 carbon atoms that may contain hydrogen or a hydroxyl group, R ⁵ is hydrogen or a methyl group, and n is an average of CH ₂ CHR ⁵ O. It is the number of added moles, and represents a number from 1 to 6. The polymer dispersing agent according to any one of claims 1 to 4, comprising at least one structural unit selected from the following general formulas (3), (4-a), (4-b), and (5). The dispersion for free abrasive grains according to one item.

In the general formula (3), R ⁶ is hydrogen or a methyl group, R ⁷ , R ⁸ and R ⁹ are the same or different and each represents hydrogen, an ethyl group or a methyl group, A is oxygen or NH, p is 1 The number is 3 or less and X ₁ ⁻ represents a counter anion.

In the general formulas (4-a) and (4-b), R ¹⁰ and R ¹¹ are the same or different and represent hydrogen or a methyl group, and X ₂ ⁻ represents a counter anion.

In the general formula (5), R ¹² represents hydrogen or a methyl group.   Furthermore, it contains at least one surfactant selected from anionic surfactants and nonionic surfactants having a cloud point of 65 ° C. or higher, and the content of the surfactant is 0.5% by mass or more and 5.0% by mass. % Of the dispersion for free abrasive grains according to any one of claims 1 to 5.   A free abrasive-containing slurry comprising the free abrasive dispersion and free abrasive according to any one of claims 1 to 6.   A silicon ingot cutting method comprising a step of cutting the silicon ingot with the wire while supplying the slurry containing the free abrasive grains according to claim 7 to the cutting portion of the wire and the silicon ingot or the entire silicon ingot. The treatment liquid containing the free abrasive grain-containing slurry according to claim 7 used for cutting a silicon ingot and the cutting powder of the silicon ingot is left as a target for stationary or centrifugal separation. Separating the heavy particles and the relatively light particles, and recovering the light particle dispersion in which the relatively light particles of the liquid to be treated are dispersed;
By heating the recovered light particle dispersion to a temperature higher than the cloud point of the dispersion for free abrasive contained in the free abrasive containing slurry, an upper layer mainly composed of oil, water and free abrasive A process for treating a slurry containing free abrasive grains, comprising: a step of separating a lower layer mainly composed of cutting powder and recovering the upper layer.   A step of adding a part or all of a deficient component to the upper layer recovered by the processing method of the free abrasive-containing slurry according to claim 9 based on the unused free abrasive dispersion. A method for regenerating a dispersion for free abrasive grains.