CN101960000A - Processing oil for brittle materials - Google Patents

Abstract

Provided is a processing oil for brittle materials that can fully supply slurry into the processing gap and has excellent processability. The processing oil for brittle materials is a combination of (a) a base oil and (b) a 2- to 6-valent polyol. Alkylene oxide adducts, nonionic surfactants with an added mole number of alkylene oxides of 2 to 50 and/or derivatives of alkylene oxide adducts of 2 to 6-membered polyols, additions of alkylene oxides Processing oil for brittle materials composed of a nonionic surfactant with a mole number of 2 to 50 and (c) bentonite, in which the content of component (b) is 0.2 based on the total amount of processing oil. ~30 mass%, and the content of component (c) is 0.1-10 mass%.

Description

Processing oils for brittle materials

technical field

The present invention relates to a processing oil for brittle materials, and more particularly, to a processing oil for brittle materials suitable for cutting brittle materials with a wire saw using loose abrasive grains.

Background technique

In the manufacture of semiconductor products, it is important to process silicon ingots, which are brittle materials, with high precision. For cutting, processing with a wire saw is generally performed from the viewpoint of processing accuracy and productivity. Generally, in wire saw processing, brittle materials are cut with a wire saw including piano wire or the like using a slurry in which free abrasive grains are dispersed in processing oil. Therefore, in addition to the lubricating performance and the cooling performance, the processing oil is also required to have the dispersing performance of free abrasive grains and the ease of washing after processing. Various techniques have heretofore been developed for this purpose.

For example, Patent Document 1 discloses a cutting oil agent containing a specific base oil such as polyethylene glycol, a thickener such as polyalkylene glycol, and water. Patent Document 2 discloses a cutting oil containing mineral oil, bentonite, a lubricant such as a fatty acid amine salt, a sulfonate-based anionic surfactant, and a glycol derivative. Patent Document 3 discloses a metalworking oil composition containing a synthetic oil, an alkyl ether of a 1- to 4-polymer polyol, and a fatty acid ester of a 1- to 4-polymer polyol. Patent Document 4 discloses a metalworking oil composition containing propylene glycol ether, a sorbitan derivative, a modified silicone, mineral oil, and the like.

As described above, various machining oils used in wire saw machining have hitherto been known. However, in recent years, semiconductor products and the like tend to be larger and more highly integrated, and accordingly, it is necessary to improve the performance of processing oils. That is, wire saw processing requires processing large materials with higher precision than conventional ones. However, when conventional processing oils are used, it is difficult to sufficiently supply slurry to the processing gap. Therefore, there are problems such as that saw marks are easily generated on the cut surface when cutting the silicon ingot, and the thickness of the wafer is difficult to be uniform.

Patent Document 1: Japanese Patent Application Laid-Open No. 3-181598

Patent Document 2: Japanese Unexamined Patent Application Publication No. H10-110180

Patent Document 3: Japanese Patent Laid-Open No. 2002-53885

Patent Document 4: Japanese Patent Laid-Open No. 2007-106835

Contents of the invention

The present invention was made under such circumstances, and an object of the present invention is to provide a processing oil for brittle materials that can sufficiently supply a slurry into a processing gap and has excellent processability.

As a result of intensive studies, the present inventors have found that in order to sufficiently supply the slurry into the machining gap, the viscosity of the machining oil must be reduced, and that the reduction in abrasive particle dispersibility usually caused by lowering the viscosity of the machining oil can be avoided by using specific components in combination, thereby The present invention has been accomplished.

That is, the present invention provides the following processing oil for brittle materials and composition for processing brittle materials having both low viscosity and excellent abrasive grain dispersibility.

1. A processing oil for brittle materials comprising (a) a base oil and (b) an alkylene oxide adduct of a 2- to 6-valent polyhydric alcohol and having an alkylene oxide addition mole number of 2 to 50 non- An ionic surfactant and/or a derivative of an alkylene oxide adduct of a 2- to 6-valent polyhydric alcohol, a non-ionic surfactant having an added mole number of 2 to 50 alkylene oxides, and (c) bentonite The blended processing oil for brittle materials, wherein the content of component (b) is 0.2 to 30% by mass and the content of component (c) is 0.1 to 10% by mass based on the total amount of processing oil.

2. The processing oil for brittle materials described in 1 above, which has a kinematic viscosity at 40°C of 2 to 30 mm ² /s.

3. The processing oil for brittle materials according to 1 or 2 above, which is used for wire saw processing.

4. A composition for processing brittle materials, comprising the processing oil for brittle materials described in 1 or 2 above and free abrasive grains.

According to the present invention, there is provided a processing oil for brittle materials having low viscosity and excellent abrasive grain dispersibility. Since the machining oil of the present invention has the above properties, it is possible to finely and uniformly supply a large amount of abrasive grains into the machining gap. Therefore, machining accuracy can be improved, and large brittle materials can be machined.

Detailed ways

The processing oil for brittle materials of this invention contains (a) base oil, (b) specific nonionic surfactant, and (c) bentonite.

The (a) base oil used in the present invention is not particularly limited, but it is preferable to use a base oil having a kinematic viscosity at 40°C of 1 to 20 mm ² /s, more preferably 2~15mm ² /s base oil.

Examples of the base oil include mineral oil and synthetic oil. Mineral oils include, for example, distilled oil obtained by atmospheric distillation of paraffinic crude oil, intermediate crude oil, or naphthenic crude oil, or vacuum distillation of residue oil obtained by atmospheric distillation, or obtained by purifying it according to a conventional method. The obtained purified oil, such as solvent purified oil, hydrogenated purified oil, dewaxed treated oil, clay treated oil, etc. Examples of synthetic oils include poly-α-olefins having 8 to 14 carbon atoms, olefin copolymers (such as ethylene-propylene copolymers, etc.), branched olefins such as polybutene and polypropylene, or their hydrogenated substances, and then polyol esters (fatty acid esters of trimethylolpropane, fatty acid esters of pentaerythritol, etc.), ester compounds such as dibasic acid esters, alkylbenzenes, etc.

In the present invention, as the base oil, any one of the above-mentioned mineral oils and the above-mentioned synthetic oils may be used alone or in combination of two or more.

As the nonionic surfactant of component (b) used in the present invention, a nonionic surfactant having an added mole number of alkylene oxide of 2 to 50 is used, specifically, a 2 to 6 polyhydric alcohol A nonionic surfactant with an alkylene oxide adduct of 2 to 50 moles of alkylene oxide added, as a derivative of an alkylene oxide adduct of 2 to 6-valent polyhydric alcohol, the addition of alkylene oxide A nonionic surfactant with a molar number of 2 to 50. As this nonionic surfactant, the compound which has an ester group is preferable.

Specific examples of 2- to 6-valent polyhydric alcohols include ethylene glycol, propylene glycol, glycerin, diglycerin, triglycerin, trimethylolalkanes (such as trimethylolethane, trimethylolpropane, trimethylol Methylbutane) and their 2-3 polymers, pentaerythritol, sorbitol, sorbitan, etc. Among them, divalent to quadrivalent polyhydric alcohols are preferred, and glycerin or sorbitan is particularly preferred.

When preparing the alkylene oxide adducts of 2-6 polyhydric alcohols, the above-mentioned polyhydric alcohols or compounds having ester groups obtained by reacting a part of hydroxyl groups with fatty acids can be directly used. Fatty acids may be linear, branched or cyclic, and may be saturated or unsaturated. The number of carbon atoms in the fatty acid is preferably 2-24, more preferably 4-20. Specifically, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, isostearic acid, etc. are mentioned.

Examples of the alkylene oxide adducts of the aforementioned polyols include polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan Sugar alcohol monooleate, polyoxyethylene glycerol monoisostearate, etc.

In the alkylene oxide adduct of the above polyhydric alcohol, the number of added moles of alkylene oxide is 2-50. When the added mole number is 1 or less, the abrasive grain dispersibility effect is low, and when it exceeds 50, the solubility in oil tends to decrease. From the above viewpoint, it is preferably 3-40, and more preferably 3-25. Preferable alkylene oxides include ethylene oxide and propylene oxide, and ethylene oxide is particularly preferred. In addition, the alkylene oxide may be added to only some of the hydroxyl groups, but it is preferable to add to all the hydroxyl groups from the viewpoint of effect.

As a derivative of the alkylene oxide adduct of a 2-6 valent polyhydric alcohol, fatty acid ester of the said alkylene oxide adduct of a polyhydric alcohol is preferable. As the fatty acid used in the preparation of the fatty acid ester, the fatty acids described above for the alkylene oxide adduct of polyhydric alcohol can be used.

In this invention, the nonionic surfactant of (b) component can be used individually by 1 type or in mixture of 2 or more types. The content of the component (b) is 0.2 to 30% by mass based on the total amount of processing oil. If it is less than 0.2% by mass, the abrasive grain dispersibility tends to decrease, and if it exceeds 30% by mass, the viscosity of the machining oil increases, making it difficult to sufficiently supply the slurry into the machining gap. From the above viewpoint, it is preferably 1 to 20% by mass, and more preferably 1 to 10% by mass.

The (c) bentonite used in the present invention is clay mainly composed of montmorillonite, and has an average particle diameter of preferably 10 μm or less, more preferably 8 μm or less.

In the present invention, as the component (c), bentonite treated with an organic substance is more preferable. The bentonite treated with organic matter refers to an organic ion complex formed by exchanging inorganic cations present between bentonite crystal layers with organic cations, that is, so-called organic bentonite. As the above-mentioned organic cation, an ammonium ion is preferable, and a quaternary ammonium ion is particularly preferable.

In this invention, the bentonite of (c) component can be used individually by 1 type or in mixture of 2 or more types. The content of the component (c) is 0.1 to 10% by mass based on the total amount of processing oil. If it is less than 0.1% by mass, the abrasive grain dispersibility tends to decrease, and if it exceeds 10% by mass, the viscosity of the machining oil increases, making it difficult to sufficiently supply the slurry into the machining gap. From the above viewpoint, it is preferably 0.5 to 5% by mass.

The kinematic viscosity at 40°C of the processing oil for brittle materials of the present invention is preferably 2-30 mm ² /s, more preferably 3-20 mm ² /s, particularly preferably 5-15 mm ² /s. When the kinematic viscosity at 40° C. is within the above-mentioned range, the slurry can be sufficiently supplied to the machining gap, and excellent processability can be obtained.

As described above, the processing oil for brittle materials of the present invention has a low kinematic viscosity. Generally, in low-viscosity machining oils, the abrasive grains tend to settle and the machining accuracy decreases. However, in the machining oil of the present invention, excellent abrasive grain dispersibility is obtained by using the above-mentioned components (b) and (c) in combination.

The processing oil for brittle materials of the present invention may contain known additives such as rust inhibitors, defoamers, antioxidants, and metal deactivators within the range that does not hinder the object of the present invention. Examples of the rust inhibitor include alkylbenzenesulfonate, dinonylnaphthalenesulfone, alkenyl succinate, polyol ester, and the like. Examples of the antifoaming agent include silicone oil, fluorosilicone oil, and fluoroalkyl ether. Examples of antioxidants include phenolic antioxidants and amine antioxidants. Examples of the metal deactivator include imidazoline, pyrimidine derivatives, thiadiazole, benzotriazole, and thiadiazole.

The compounding amount of these additives can be appropriately selected according to the purpose, but the total of these additives is usually about 0.01 to 5% by mass based on the total amount of the processing oil.

The processing oil for brittle materials of the present invention can be suitably used when wire sawing brittle materials using a wire saw, a multi-wire saw, or the like. Examples of brittle materials include silicon, crystal, ceramics, and carbon. In wire saw processing, free abrasive grains are generally used, and the processing oil for brittle materials of the present invention and the free abrasive grains are mixed to prepare a composition (slurry) for brittle material processing. The free abrasive grains can be used without particular limitation, and examples thereof include SiC (silicon carbide) abrasive grains, alumina abrasive grains, and diamond abrasive grains. The blending amount of free abrasive grains can be appropriately determined depending on the purpose, but usually the mass ratio of processing oil for brittle materials:free abrasive grains is 95:5 to 10:90, preferably 90:10 to 30:70.

Example

Next, although an Example demonstrates this invention more concretely, this invention is not limited to these examples.

Examples 1-5, Comparative Examples 1-10

Processing oils having the compositions shown in Table 1 were prepared.

[Table 1]

Base oil: mineral oil (kinematic viscosity at 40°C: 3.3 mm ² /s)

Ester compound 1: polyoxyethylene sorbitan trioleate (added moles: 20)

Ester compound 2: polyoxyethylene sorbitan monolaurate (added mole number 20)

Ester compound 3: polyoxyethylene glycerol monoisostearate (added moles: 10)

Ester compound 4: polyoxyethylene sorbitan monolaurate (added mole number 6)

Ester compound 5: polyoxyethylene sorbitan monooleate (added mole number 6)

Ester compound 6: sorbitan monolaurate (added mole number 0)

Ether compound 1: polyoxyethylene lauryl ether (addition mole number 6)

Ether compound 2: polyoxyethylene oleyl ether (added mole number 6)

Fatty acid salt 1: Oleic acid N-(2-hydroxyethyl)piperazine salt

Bentonite: Niyu-Dolben (manufactured by Shiraishi Industry Co., Ltd.)

[Abrasive dispersion stability test]

The obtained processing oil was subjected to an abrasive dispersion stability test by the method shown below.

1. 40 g of abrasive grains (GC#1000 manufactured by Fujimi Co., Ltd.) and 40 g of processing oil were mixed to prepare a slurry.

2. Immediately after preparation, add the slurry into a 100ml sample bottle and place it at 30°C for 24 hours.

3. The thickness (mm) of the entire liquid and the thickness (mm) of the upper abrasive grain dispersion layer were measured, and the ratio of the abrasive grain separation layer was obtained by the following formula to study the abrasive grain dispersion stability.

Ratio of abrasive separation layer (%) = thickness of abrasive separation layer/thickness of total liquid × 100

The results are shown in Table 2.

[Kinematic viscosity at 40°C]

Measured according to JIS K 2242. The measurement results are shown in Table 2.

[Table 2]

(The kinematic viscosity at 40° C. of Comparative Example 10 could not be measured due to gelation)

The machining oils of Examples 1 to 5 exhibited excellent abrasive grain dispersibility while having a low viscosity, and are expected to be excellent in workability. On the other hand, although the processing oils of Comparative Example 9 and Comparative Example 10 were excellent in abrasive grain dispersibility, they could not achieve low viscosity. Therefore, when the machining oils of Comparative Example 9 and Comparative Example 10 were used, it was difficult to supply a sufficient amount of abrasive grains into the narrow machining gap.

The comparison of Examples 1-5 with Comparative Example 1, Comparative Example 6, and Comparative Example 7 suggests that the effect of the present invention is the synergistic effect of (B) component and (C) component. This is attributable to selecting a specific ester compound (B) component and using other surfactants instead of the comparative examples 2 to 5 (B) component, and the effects of the present invention could not be exhibited.

Industrial applicability

The processing oil of the present invention is suitable for wire saw processing, and since it has low viscosity and excellent abrasive particle dispersibility, it can finely and uniformly supply a large amount of abrasive particles into the processing gap. Therefore, machining accuracy is improved, and large brittle materials can be machined.

Claims (4)

1. A processing oil for brittle materials comprising (a) a base oil and (b) an alkylene oxide adduct of a 2- to 6-valent polyhydric alcohol and having an alkylene oxide addition mole number of 2 to 50 non- An ionic surfactant and/or a derivative of an alkylene oxide adduct of a 2- to 6-valent polyhydric alcohol, a non-ionic surfactant having an added mole number of 2 to 50 alkylene oxides, and (c) bentonite The blended processing oil for brittle materials, wherein the content of component (b) is 0.2 to 30% by mass and the content of component (c) is 0.1 to 10% by mass based on the total amount of processing oil. 2. The processing oil for brittle materials according to claim 1, which has a kinematic viscosity at 40°C of 2 to 30 mm ² /s. 3. The processing oil for brittle materials according to claim 1 or 2, which is used for wire saw processing. 4. A composition for processing brittle materials, comprising the processing oil for brittle materials according to claim 1 or 2 and free abrasive grains.