JP2011230275A - Ingot cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ingot cutting method which can improve regeneration efficiency of a cutting oil composition, with a simple operation, by separating cutting powder from waste oil solution which contains used cutting oil composition and the cut powder with high separation efficiency, and recovering the oily component at high yield.SOLUTION: In the ingot cutting method, an ingot is cut by a fixed abrasive wire saw using the cutting oil composition for the fixed abrasive wire saw. The cutting oil composition for the fixed abrasive wire saw contains 30-100 wt.% of a specific polyether compound. The ingot cutting method includes a cutting step of cutting the ingot, a powder removal step of removing at least the cut powder from the waste oil solution, and a step of reusing the residual liquid obtained by removing at least the cut powder from the waste oil solution for cutting the ingot. The powder removal step includes a step of separating the waste oil solution into an upper layer having the polyether compound as a main component, an intermediate layer having water as the main component, and a deposition layer (a lower layer) of the cut powder.

Description

  The present invention relates to a method for cutting an ingot using a cutting oil composition for a fixed abrasive wire saw, and a method for regenerating the cutting oil composition for a fixed abrasive wire saw used for cutting the ingot.

  Conventionally, what contains a polyether compound as an oil component is known as a cutting oil composition used when cutting a silicon ingot etc. with a wire saw using an abrasive grain (refer patent document 1 and patent document 2).

  In recent years, attempts have been made to reuse cutting oil compositions from the viewpoints of productivity and economy. For example, Patent Document 3 below discloses that a dispersion such as abrasive grains and cutting powder of an ingot and a cutting oil composition are separated by centrifugation and the cutting oil composition is reused.

  On the other hand, a method of cutting a silicon ingot or the like using a fixed abrasive wire saw instead of a loose abrasive wire saw is known. This method has an advantage that the ingot can be used effectively because the ingot can be cut less. In addition, since no abrasive grains are mixed in the cutting oil composition, the properties such as the viscosity of the cutting oil composition at the time of cutting are hardly changed, and the wafer can be stably produced and the wafer can be easily cleaned. It is more advantageous than a cutting method using a grain wire saw.

Japanese Patent Laid-Open No. 11-286693 JP-A-11-323376 JP-A-01-316170

  However, even when a fixed-abrasive wire saw is used for cutting the ingot, the cutting powder of the ingot is mixed in the cutting oil composition, so that the cutting powder needs to be separated. In the centrifugal separation method, even if high-speed rotation is performed, it takes a very long time to separate the cutting powder, and the separation efficiency is poor, so that the regeneration efficiency of the cutting oil composition is low. This problem hinders the productivity improvement of silicon wafers.

  In order to improve the regeneration efficiency of the cutting oil composition, it is necessary to improve not only the cutting powder separation efficiency but also the oil recovery rate.

  The present invention is an ingot cutting method using a fixed abrasive wire saw that regenerates and repeatedly uses a used cutting oil composition, and includes the used cutting oil composition and cutting powder generated by cutting the ingot. Provided is an ingot cutting method capable of improving the regeneration efficiency of a cutting oil composition by separating cutting powder with high separation efficiency and recovering oil with a high recovery rate by simple operation from waste oil. .

Ingot cutting method of the present invention,
An ingot cutting method for cutting an ingot with a fixed abrasive wire saw using a cutting oil composition for a fixed abrasive wire saw,
The cutting oil composition for a fixed abrasive wire saw contains 30 to 100% by weight of a polyether compound represented by the following general formula (1):
R—O— (EO) _m (AO) _n —H (1)
(However, R is a hydrocarbon group having 1 to 24 carbon atoms, EO is an oxyethylene group, AO is an oxyalkylene group having 3 or 4 carbon atoms, and m and n are average added moles of EO and AO, respectively. M represents 2 to 20, n represents a number representing 0 to 20, and the arrangement of EO and AO may be block or random.)
A cutting step of cutting an ingot with the fixed abrasive wire saw using the cutting oil composition for the fixed abrasive wire saw;
A powder removing step of removing at least the cutting powder from an oil drainage liquid containing the cutting oil composition for the fixed abrasive wire saw and the cutting powder of the ingot generated in the cutting step;
The residual liquid obtained by removing at least the cutting powder from the waste oil liquid is reused for cutting an ingot as a cutting oil composition for a fixed abrasive wire saw, or the general formula (1) is used for the residual liquid. A cutting oil composition for a fixed abrasive wire saw obtained by adding a polyether compound and / or water represented by the following, and using the cutting oil composition for a fixed abrasive wire saw for cutting an ingot,
The powder removal step comprises:
A first step of adjusting the water content of the drain oil to 28 to 70 wt% when the water content of the drain oil is not 28 to 70 wt%;
An oil drainage liquid having a water content of 28 to 70% by weight is heated to a temperature equal to or higher than the cloud point measured using a 10% by weight aqueous solution of the polyether compound, and the polyether compound is the main component. A second step of separating the upper layer, the intermediate layer containing water as a main component, and the precipitated layer (lower layer) of the cutting powder;
And a third step of removing at least a precipitated layer (lower layer) of the cutting powder from the drained oil separated into three layers in the second step.

The method for regenerating the cutting oil composition for the fixed abrasive wire saw of the present invention is as follows.
A method for regenerating a cutting oil composition for a fixed abrasive wire saw used for cutting an ingot,
The cutting oil composition for a fixed abrasive wire saw before use contains 30 to 100% by weight of a polyether compound represented by the following general formula (1),
R—O— (EO) _m (AO) _n —H (1)
(However, R is a hydrocarbon group having 1 to 24 carbon atoms, EO is an oxyethylene group, AO is an oxyalkylene group having 3 or 4 carbon atoms, and m and n are average added moles of EO and AO, respectively. M = 2 to 20 and n = 0 to 20, and the arrangement of EO and AO may be block or random.)
When the water content of the drainage fluid containing the cutting oil composition for the fixed abrasive wire saw after use and the cutting powder of the ingot is not 28 to 70% by weight, the water content of the drainage fluid is A first step of preparing 28-70% by weight;
An oil drainage liquid having a water content of 28 to 70% by weight is heated to a temperature equal to or higher than the cloud point measured using a 10% by weight aqueous solution of the polyether compound, and the polyether compound is the main component. A second step of separating into an upper layer, an intermediate layer containing water as a main component, and a precipitated layer (lower layer) of the cutting powder;
A third step of removing at least a precipitated layer (lower layer) of the cutting powder from the drained oil separated into three layers in the second step; and removing at least the lower layer from the drained fluid in the third step. And 4th step of adding the polyether compound and / or water represented by the general formula (1) to the residual liquid obtained to obtain a cutting oil composition for a fixed abrasive wire saw.

  In the present invention, the cutting powder can be separated from the drained liquid with a high separation efficiency by a simple operation, and therefore the regeneration efficiency of the cutting oil composition for a fixed abrasive wire saw is high.

  In the present invention, a used cutting oil composition for a fixed abrasive wire saw (hereinafter, the “cutting oil composition for a fixed abrasive wire saw” may be simply referred to as a “cutting oil composition”) and a cutting powder. The amount of water contained in the drained oil is adjusted to 28 to 70% by weight as necessary, and the drained oil whose water content is adjusted is adjusted to a 10% by weight aqueous solution of a specific polyether compound contained in the cutting oil composition. By heating to a temperature equal to or higher than the cloud point measured by using, to separate the drained oil into three layers, and cutting from the drained fluid by removing at least the precipitated layer (lower layer) of the cutting powder from the three layers Remove the powder. In the present invention, since a separation method using a cloud point is employed for separating the cutting powder and the specific polyether compound and separating the cutting powder from the oil discharge liquid, the centrifugal separator is used for regeneration of the cutting oil composition. Such a special apparatus is unnecessary and economical, and the cutting powder and the specific polyether compound are separated well, and the cutting powder is efficiently separated from the drained oil. Therefore, the cutting oil composition can be efficiently regenerated by reusing the residual liquid containing the specific polyether compound obtained by removing at least the lower layer from the drained oil.

  The precipitation layer (lower layer) of the cutting powder is substantially composed of cutting powder. As described later, the precipitation layer is formed on either water or the polyether compound due to occurrence of a cloud point phenomenon. Is also a layer formed by precipitation of the cutting powder that is difficult to disperse, and therefore, in addition to the cutting powder, the precipitation layer includes at least one component of components constituting the cutting oil composition for a fixed abrasive wire saw ( For example, water and / or a polyether compound) may be contained.

(Cutting oil composition for fixed abrasive wire saw)
The cutting oil composition used in the ingot cutting method of the present invention is an ingot to which a cutting oil composition obtained after cutting an ingot by a fixed abrasive wire saw (hereinafter, sometimes simply referred to as “wire saw”) is attached. A polyether compound represented by the following general formula (1) is contained from the viewpoint of facilitating washing of the sliced product, improving the cutting performance of the wire saw, and improving the separation efficiency of the cutting powder.
R—O— (EO) _m (AO) _n —H (1)

  In the general formula (1), R is a hydrocarbon group having 1 to 24 carbon atoms, EO is an oxyethylene group, AO is an oxyalkylene group having 3 or 4 carbon atoms, and m and n are averages of EO and AO, respectively. The number of moles added, m is 2 to 20, n is a number representing 0 to 20, and the arrangement of EO and AO may be block or random. The compound represented by the general formula (1) may be used alone or in combination of two or more.

  The polyether compound represented by the general formula (1) can be obtained, for example, by adding an alkylene oxide compound to monohydric alcohol or phenol using KOH or the like as a catalyst. In the polyether compound obtained as described above, the number of added moles of oxyethylene groups and oxypropylene groups in the polyether compound has a distribution.

(EO) _m (AO) _n in the general formula (1) may be composed of an oxyethylene group alone, but is composed of an oxyethylene group and an oxyalkylene group having 3 or 4 carbon atoms. May be. (EO) _m (AO) When _n is composed of an oxyethylene group and an oxyalkylene group having 3 or 4 carbon atoms, the arrangement of EO and AO may be block or random. When the arrangement of EO and AO is a block, the number of EO blocks and the number of PO blocks may be one each as long as each average added mole number is within the above range, but two or more. There may be. When the number of EO blocks is two or more, the number of EO repetitions in each block may be the same or different. Even when the number of PO blocks is two or more, the number of PO repetitions in each block may be the same or different.

  AO in the general formula (1) is an oxyalkylene group having 3 carbon atoms (oxypropylene group) or an oxyalkylene group having 4 carbon atoms (oxybutylene group). From the viewpoint of easy control, it is preferably an oxypropylene group.

  The carbon number of R (hydrocarbon group) in the general formula (1) is 1 to 24 from the viewpoint of improving the cutting performance of the wire saw and facilitating washing of the sliced product, but from the same viewpoint, 3 to 18, preferably 4 to 12, more preferably 4 to 8, more preferably 4 to 6 from the viewpoint of improving the separation efficiency of the cutting powder and reducing the foaming of the cutting oil composition. It is more preferable.

  R (hydrocarbon group) may be either an aliphatic group or an aromatic group. In the aliphatic group, either a saturated or unsaturated group may be used, and either a linear or branched group may be used. Among them, R is preferably a butyl group, a hexyl group or a 2-ethylhexyl group, more preferably a butyl group, from the viewpoint of improving the separation efficiency of the cutting powder and reducing the foaming of the cutting oil composition.

  In the general formula (1), m is a number representing 2 to 20, and n is a number representing 0 to 20. However, m is an improvement in cutting powder separation efficiency, facilitating cleaning of a sliced product, and a cutting oil composition. From the viewpoint of improving the fluidity, it is preferably 2 to 10, more preferably 2 to 9, further preferably 3 to 8, and still more preferably 4 to 6. On the other hand, n is preferably 0 to 10 and more preferably 2 to 8 from the viewpoint of improving the separation efficiency of the cutting powder, improving the fluidity of the cutting oil composition, and reducing the foaming of the cutting oil composition. Preferably, it is 3-5. From the viewpoint of improving the separation efficiency of the cutting powder, facilitating the washing of the sliced product, and improving the fluidity of the cutting oil composition, m + n is preferably 4 to 20, more preferably 4 to 18, and 8 More preferably, it is 10-10. From the viewpoint of improving the separation efficiency of the cutting powder and facilitating cleaning of the sliced product, it is preferable that the relational expression m ≧ n> 0 is satisfied. That is, in the present invention, m in the general formula (1) is 2 to 9, n from the viewpoint of improving the cutting powder separation efficiency, facilitating cleaning of the sliced product, and improving the fluidity of the cutting oil composition. Is preferably 2 to 8, m + n is 4 to 18, and the relational expression m ≧ n> 0 is satisfied, m in the general formula (1) is 3 to 8, n is 3 to 5, and m + n is 8 to 8. 10. It is more preferable that the relational expression m ≧ n> 0 is satisfied.

  In the present invention, R is carbonized with 4 to 12 carbon atoms from the viewpoint of improving the cutting performance of the wire saw, facilitating cleaning of the sliced product, improving the separation efficiency of the cutting powder, and facilitating the control of the cloud point. It is preferably a hydrogen group, satisfying the relational expression m ≧ n> 0, and AO is preferably an oxypropylene group, improving the cutting performance of the wire saw, facilitating cleaning of the sliced product, improving the separation efficiency of the cutting powder, From the viewpoint of easy control of the cloud point and low foaming of the cutting oil composition, R is a hydrocarbon group having 4 to 8 carbon atoms, satisfies the relational expression m ≧ n> 0, and AO is oxy It is more preferable that it is a propylene group, and from the same viewpoint, it is more preferable that R is a hydrocarbon group having 4 to 6 carbon atoms, satisfies the relational expression m ≧ n> 0, and AO is an oxypropylene group.

  The content of the polyether compound in the cutting oil composition is from the viewpoint of improving the cutting powder separation efficiency, improving the recovery rate of the polyether compound, facilitating cleaning of the sliced product, and improving the cutting performance of the wire saw. Although it is 30 to 100% by weight, from the same viewpoint, it is preferably 30 to 70% by weight, and more preferably 30 to 50% by weight.

  The cutting oil composition may contain water according to the conditions at the time of cutting the ingot with a wire saw. When the cutting oil composition contains water, the cutting oil composition can exhibit a cooling effect when cutting with a wire saw.

  When the cutting oil composition contains water, the content of water is preferably 70% by weight or less from the viewpoint of improving the lubricity of the cutting oil composition. From the viewpoint of improving the cutting performance of the wire saw, the cooling effect by the cutting oil composition is preferably high, and the water content is preferably 28% by weight or more, and from 30% by weight or more from the viewpoint of improving the cooling effect. More preferably, it is more preferably 50% by weight or more. Therefore, the water content in the cutting oil composition is preferably 28 to 70% by weight, more preferably 30 to 70% by weight, and even more preferably 50 to 700% by weight.

  As the water contained in the cutting oil composition, for example, ultrapure water, pure water, ion exchange water, or distilled water can be used, but ultrapure water, pure water, or ion exchange water is preferable, 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 cutting oil composition may contain one or more compounds selected from hydrocarbon compounds, sparingly water-soluble alkyl esters, and sparingly water-soluble alkyl ketones as necessary. By containing these compounds, the lubricity of the cutting oil composition is improved.

  Examples of the hydrocarbon compound include paraffins and / or olefins having 6 to 30 carbon atoms, which are liquid at the temperature at which the wafer is cleaned, and having a saturated or unsaturated bond of a linear or branched chain, or wafers. Examples thereof include aromatic and / or aliphatic hydrocarbon compounds that are liquid at the temperature at which they are washed.

  Examples of the alkyl esters include monoesters, diesters, and triesters having 6 to 40 carbon atoms that are liquid at the temperature at which the wafer is cleaned. Among them, an ester of a higher fatty acid having 6 to 18 carbon atoms and a diol or triol having 2 to 8 carbon atoms; an ester of a higher alcohol having 1 to 18 carbon atoms and a dicarboxylic acid or tricarboxylic acid having 2 to 8 carbon atoms is preferable.

  As said alkyl ketones, a C6-C40 dialkyl ketone is preferable.

  The hydrocarbon compounds, poorly water-soluble alkyl esters and poorly water-soluble alkyl ketones may be used alone or in admixture of two or more.

  The cutting oil composition may optionally further contain additives such as thickeners, dispersants, rust inhibitors, chelating agents, basic substances, and other surfactants.

  The cutting oil composition may contain a water-soluble organic compound as a medium for various components such as the polyether compound.

(Method for preparing cutting oil composition)
The method for preparing the cutting oil composition is not limited at all, and can be prepared by mixing the polyether compound, and, if necessary, water and further optional components.

(Ingot cutting method)
The ingot cutting method of the present invention includes a cutting oil composition used for cutting an ingot and a cutting powder of the ingot after the cutting step of cutting the ingot with a fixed abrasive wire saw using the cutting oil composition. A powder removing step of removing at least cutting powder from the oil liquid to obtain a residual liquid, a step of reusing the residual liquid as a cutting oil composition for cutting an ingot, or a polyether compound and / or water in the residual liquid Is added to obtain a cutting oil composition, and the cutting oil composition is used for cutting an ingot.

  In the ingot cutting method of the present invention, the removal of the cutting powder is performed when the drain oil is heated to a temperature higher than the cloud point measured using a 10% by weight aqueous solution of the polyether compound. Therefore, at least cutting powder can be separated from the drained oil with a simple operation and high separation efficiency. Since the cutting powder produced at the time of cutting is dispersed in the mixed liquid containing the polyether compound and water, the separation efficiency of the cutting powder from the mixed liquid is poor. However, when the mixed solution is separated into an oil layer and an aqueous layer by utilizing the cloud point phenomenon, the cutting powder is difficult to disperse in both the oil layer and the aqueous layer and forms a precipitated layer. The cutting powder can be separated from the waste oil with high separation efficiency. Therefore, the ingot cutting method of the present invention has high regeneration efficiency of the cutting oil composition, can contribute to improvement of wafer productivity, and is economical and environmentally friendly.

(Cutting process)
In the cutting step, the ingot is cut with a fixed abrasive wire saw (hereinafter sometimes abbreviated as “wire saw”). There is no restriction | limiting in particular about the wire saw apparatus used for a cutting | disconnection of an ingot, It can carry out using a conventionally well-known apparatus. There are no particular restrictions on the wire saw. For example, diamond or SiC abrasive grains are fixed to a piano wire mainly composed of iron or an iron alloy by plating with nickel, copper or chromium, or are fixed by a resin adhesive. And the like.

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

  The wire saw is supplied from, for example, a wire saw supply reel, and is wound and arranged in a groove having a predetermined interval provided on the main roller. The wire saw 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 to 1000 m / min. The wire saw device may be a single type that performs cutting with a single wire.

  The drained oil produced by cutting the ingot contains the used cutting oil composition and the cutting powder, and is temporarily stored, for example, in a dip tank included in the wire saw device.

(Powder removal process)
The removal of the cutting powder includes the first step of adjusting the water content of the drained oil to a predetermined amount, and the drained fluid adjusted in the first step in three layers, an upper layer, an intermediate layer, and a lower layer. A second step of separating, and a third step of removing at least a precipitated layer (lower layer) of the cutting powder from the oil drained liquid separated into three layers in the second step.

(First step)
In the first step, the water content of the waste oil is adjusted to 28 to 70% by weight from the viewpoint of enabling separation of the waste oil into three layers in the second step described later. From the viewpoint of improving efficiency, the water content of the waste oil is preferably 28 to 50% by weight.

  In addition, if the water content of the waste oil before adjustment is any amount within the range of 28 to 70% by weight, the water may not necessarily be added, but the water is 70% by weight. It may be added as long as it does not exceed.

(Second step)
In the second step, first, an oil drainage liquid containing 28 to 70% by weight of water is heated to a temperature equal to or higher than the cloud point measured using a 10% by weight aqueous solution of the polyether compound. Thereafter, when the drained oil is allowed to stand, the drained oil is separated into an upper layer mainly composed of the polyether compound, an intermediate layer mainly composed of water, and a precipitated layer (lower layer) of cutting powder. Here, the main component means a component having the largest content among the constituent components constituting the layer.

  The cloud point (° C.) measured using a 10% by weight aqueous solution of the polyether compound is a temperature at which the aqueous solution starts to become cloudy when the temperature of the aqueous solution containing the polyether compound at a concentration of 10% by weight is increased. That is. When the temperature of the aqueous solution rises and the movement of water molecules becomes active, the hydrogen bond between the hydrophilic group portion of the polyether compound in the liquid and the water molecule is broken, and the polyether compound loses its solubility in water. Therefore, if the drained oil solution containing the polyether compound is heated to a temperature equal to or higher than the cloud point measured using a 10% by weight aqueous solution of the polyether compound and then left to stand, the polyisocyanate having a specific gravity smaller than that of water. The ether compound moves to the upper side of the water, and the cutting powder having a specific gravity larger than that of the water settles, so that the drained oil is separated into three layers.

  The cloud point is preferably 30 ° C. or higher, more preferably 50 ° C. or higher, from the viewpoint of improving the cutting performance of the wire saw and improving the separation efficiency of the cutting powder.

  When the cloud point measured using a 10% by weight aqueous solution of the polyether compound is 50 ° C. or more, from the viewpoint of improving the separation efficiency of the cutting powder, in the second step, the oil discharge liquid is 10% of the polyether compound. It is preferable to heat to a temperature (separation temperature) 5 to 20 ° C. higher than the cloud point measured using a weight% aqueous solution, and more preferable to heat to a temperature 15 to 20 ° C. higher.

  In the second step, the oil drainage liquid is preferably stirred before and / or during heating from the viewpoint of improving the separation efficiency of the cutting powder.

(Third step)
In the third step, at least the precipitated layer (lower layer) of the cutting powder is removed from the drained oil liquid separated into the three layers in the second step, but the three layers are separated from the viewpoint of improving the cutting powder separation efficiency. You may remove both a lower layer and the intermediate | middle layer which has water as a main component from waste oil liquid.

(Reuse of remaining liquid)
The residual liquid obtained by removing at least the cutting powder from the waste oil may be reused as it is for cutting an ingot as a cutting oil composition as long as the concentration of the polyether compound is 30% by weight or more. In addition, as long as the concentration of the polyether compound is 30% by weight or more, the concentration of the polyether compound is adjusted by adding the polyether compound represented by the general formula (1) and / or water. It may be used for cutting. Moreover, when the polyether compound in a residual liquid is less than 30 weight%, the polyether compound represented by the said General formula (1) and / or water are added to the said residual liquid, and a cutting oil composition is obtained. The cutting oil composition may be used for cutting an ingot.

  The amount of the polyether compound and / or water added to the residual liquid is preferably determined based on the measurement result obtained by measuring the content of the polyether compound and the content of water in the residual liquid. Alternatively, a decrease amount of the polyether compound and a decrease amount of water accompanying the cutting step and the powder removing step are estimated in advance, respectively, and the same amount of the polyether compound and / or water as the decrease amount is one. You may make it replenish the waste oil liquid or residual liquid obtained by formation of a slice product or a some slice product.

1. Preparation of Cutting Oil Composition The cutting oil compositions of Examples 1 to 8 and Comparative Examples 1 to 7 were obtained by blending and mixing each component so as to have the composition (% by weight) shown in Table 1.

(Measurement of cloud point)
(1) An aqueous solution having a polyether compound concentration of 10% by weight is prepared, and 50 cm ^{3 is} placed in a 100 cc test tube.
(2) Put the test tube in a water bath and raise the temperature of the preparation liquid from room temperature at a rate of 2 ° C./min while manually stirring the preparation liquid using a glass rod-shaped thermometer.
(3) When the turbidity does not disappear even after stirring, the temperature of the preparation 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) Repeat (2) to (4) twice, and use the average value of the temperatures read in (3) as the cloud point.

  The cutting powder separation efficiency (powder separation efficiency) and oil recovery rate were calculated as follows.

[About Examples 1 to 6]
In a separatory funnel, 2 g of a silicon wafer cutting powder model (Silicon dioxide: manufactured by S5631 sigma-aldrich) was added to each of the cutting oil compositions (200 g) of Examples 1 to 6 and stirred for testing. After preparing the drainage liquid, the temperature of the test drainage liquid was raised to the separation temperature (70 ° C for Examples 1 to 4 and 6 and 50 ° C for Example 5), and then allowed to stand for 1 hour. After standing for 1 hour, it was confirmed that the test oil drain solution was divided into three layers: an upper layer (oil layer), an intermediate layer (water layer), and a lower layer (precipitation layer).

The lower layer was removed from the test waste oil, and the powder separation efficiency was calculated from the following (formula A).
Powder separation efficiency (%) = {Cutting powder amount obtained by washing the lower layer with a large amount of water and drying (g) / Cutting powder amount added to cutting oil composition (g)} × 100% (A formula )

  The oil recovery rate was calculated from the following (Formula B) using the value obtained by measuring the total water content of the upper layer and the intermediate layer by the Karl Fischer method. At that time, the amount of the cutting powder that could exist in the upper layer or the middle layer was negligible, so it was ignored.

  Oil recovery rate (%) = [{(weight of upper layer (g) + weight of intermediate layer (g)) − (water content in upper layer (g) + water content in intermediate layer (g))} / oil blended Quantity (g)] x 100% (Type B)

[About Example 7]
After performing the test oil drainage in the same manner as in Example 1, both the lower layer and the intermediate layer were removed from the test oil drainage, and the amount of cutting powder and the amount of water in the upper layer were removed. Was measured, and the powder separation efficiency was calculated from the following (C formula), and the oil recovery rate was calculated from the following (D formula).

  Powder separation efficiency (%) = {Cutting powder amount obtained by washing the lower layer and the intermediate layer with a large amount of water and then dried (g) / Cutting powder amount added to the cutting oil composition (g)} × 100% (C type)

  Oil recovery rate (%) = {(weight of upper layer (g) −water content of upper layer (g)) / mixed oil content (g)} × 100% (D formula)

[About Example 8]
In a separatory funnel, 2 g of a silicon wafer cutting powder model (Silicon dioxide: manufactured by S5631 sigma-aldrich) was added to the cutting oil composition (200 g) of Example 8 and agitated to give a test waste oil solution. After the preparation, 50 parts by weight of water was added to 100 parts by weight of the cutting oil composition, and the mixture was further stirred to obtain a test oil drain liquid having an oil content of 67% by weight. Then, after raising the temperature of the test waste oil to the separation temperature (70 ° C.), it was allowed to stand for 1 hour to separate the layers, and in the same manner as in Example 1, the powder separation efficiency was The oil recovery rate was calculated from the above (Formula B).

[Comparative Example 1]
In a separatory funnel, 2 g of a silicon wafer cutting powder model (Silicon dioxide: manufactured by S5631 sigma-aldrich) was added to the cutting oil composition (200 g) of Comparative Example 1 and stirred to give a test oil discharge liquid. After the preparation, the temperature of the test oil drainage liquid was raised to 30 ° C., and then allowed to stand for 1 hour for layer separation, and the powder separation efficiency was calculated from the above (Formula A) in the same manner as in Example 1. Although the lower layer (precipitated layer) was present, the liquid layer (supernatant layer) on the lower layer was not separated into an oil layer (upper layer) and an aqueous layer (intermediate layer). Calculated from (E equation).

  Oil recovery rate when not layered (%) = {(weight of supernatant layer (g) −water content of supernatant layer (g)) / mixed oil content (g)} × 100% (E formula)

[Comparative Example 2]
In the separatory funnel, 2 g of a silicon wafer cutting powder model (Silicon dioxide: manufactured by S5631 sigma-aldrich) was added to the cutting oil composition (200 g) of Comparative Example 2 and stirred to give a test oil discharge liquid. Prepared. Using a centrifuge (3K30C: manufactured by Kubota Corporation), the test oil was separated at 3,000 rpm for 5 hours at 30 ° C., and the lower layer (precipitation layer) was removed. The powder separation efficiency was calculated from the above (Formula A), and the oil recovery rate was calculated from the above (Formula E). The supernatant layer was not separated into an oil layer (upper layer) and an aqueous layer (intermediate layer).

[Comparative Examples 3 to 7]
In the same manner as in Example 1, the powder separation efficiency was calculated from (Formula A), and the oil recovery rate was calculated from (Formula B). In the cutting oil compositions of Comparative Examples 5 to 7, the lower layer (precipitation layer) was present, but the supernatant layer was not separated into the oil layer (upper layer) and the water layer (intermediate layer), so the oil recovery rate was Calculated from the above (E formula).

Further, the quality of powder separation efficiency and oil recovery rate was relatively evaluated according to the following criteria.
(Evaluation criteria for powder separation efficiency)
A: 90% or more B: 80% or more and less than 90% C: 70% or more and less than 80% D: Less than 70% (Evaluation criteria for oil recovery rate)
A: 90% or more B: 80% or more and less than 90% C: 70% or more and less than 80% D: Less than 70%

  As shown in Table 1, polyether containing cutting oil compositions and cutting powders of Examples 1 to 8 and containing 28 to 70% by weight of water in the cutting oil composition. When heated to a temperature above the cloud point measured using a 10% by weight aqueous solution of the compound, the drained oil is separated into an upper layer, an intermediate layer, and a lower layer. The cutting powder can be removed by cutting, and by removing the lower layer and the intermediate layer, the cutting powder can be removed from the drained oil with higher separation efficiency. In addition, when the waste oil is separated into an upper layer, an intermediate layer, and a lower layer using the cloud point phenomenon, the cutting powder and the polyether compound are well separated, so that the lower layer is removed from the waste oil. The polyether compound can be recovered at a high recovery rate.

Details of each component in Table 1 are as follows.
(1) C ₄ —O— (EO) ₅ (PO) ₄ —H (weight average molecular weight 526)
(2) C ₄ —O— (EO) ₉ (PO) ₇ —H ((Kao Corporation; weight average molecular weight 876)
(3) C ₁₂ —O— (EO) _2.5 (PO) _2.5 —H
(Kao Corporation; weight average molecular weight 441)
_{(4) C 6 -O- (EO} ) 2 -H
(Made by Kao; weight average molecular weight 190)
(5) Polyethylene glycol (manufactured by Kao Corporation; weight average molecular weight 300)

The weight average molecular weight is a value calculated based on a peak in a chromatogram obtained by applying a gel permeation chromatography (GPC) method under the following conditions.
Column: G4000PWXL + G2500PWXL (Tosoh Corporation)
Eluent: (0.2 M phosphate buffer) / (CH ₃ CN) = 9/1 (volume ratio)
Flow rate: 1.0 mL / min
Column temperature: 40 ° C
Detector: RI detector Standard material: Polystyrene

The method for producing the substance (1) is as follows. The autoclave was charged with 74.1 g (1 mol) of butanol and 0.30 g (0.4 wt%) of KOH (catalyst), the air in the autoclave was replaced with nitrogen, and the temperature in the autoclave was adjusted to 130 while stirring the butanol. The temperature was raised to ° C. After introducing 220 g (5 mol) of ethylene oxide into the autoclave at a pressure of 3.5 kg / cm ² and reacting butanol with ethylene oxide until the pressure decreases and becomes constant, the temperature in the autoclave is increased to 120 ° C. The temperature was lowered to ° C. Next, 232 g (4 mol) of propylene oxide was introduced into the autoclave at a pressure of 3.5 kg / cm ² . After the butanol and propylene oxide were reacted until the pressure decreased and became constant, the temperature in the autoclave was lowered to room temperature to obtain about 520 g of the substance (1).

  According to the present invention, the cutting oil composition can be separated with high separation efficiency from the drained oil liquid containing the used cutting oil composition and the cutting powder with a simple operation and the oil can be collected with a high recovery rate. Good recycling efficiency. Therefore, the present invention can contribute to improvement of wafer productivity.

Claims (4)

An ingot cutting method for cutting an ingot with a fixed abrasive wire saw using a cutting oil composition for a fixed abrasive wire saw,
The cutting oil composition for a fixed abrasive wire saw contains 30 to 100% by weight of a polyether compound represented by the following general formula (1):
R—O— (EO) _m (AO) _n —H (1)
(However, R is a hydrocarbon group having 1 to 24 carbon atoms, EO is an oxyethylene group, AO is an oxyalkylene group having 3 or 4 carbon atoms, and m and n are average added moles of EO and AO, respectively. M represents 2 to 20, n represents a number representing 0 to 20, and the arrangement of EO and AO may be block or random.)
A cutting step of cutting an ingot with the fixed abrasive wire saw using the cutting oil composition for the fixed abrasive wire saw;
A powder removing step of removing at least the cutting powder from an oil drainage liquid containing the cutting oil composition for the fixed abrasive wire saw and the cutting powder of the ingot generated in the cutting step;
The residual liquid obtained by removing at least the cutting powder from the waste oil liquid is reused for cutting an ingot as a cutting oil composition for a fixed abrasive wire saw, or the general formula (1) is used for the residual liquid. A cutting oil composition for a fixed abrasive wire saw obtained by adding a polyether compound and / or water represented by the following, and using the cutting oil composition for a fixed abrasive wire saw for cutting an ingot,
The powder removal step comprises:
A first step of adjusting the water content of the drain oil to 28 to 70 wt% when the water content of the drain oil is not 28 to 70 wt%;
An oil drainage liquid having a water content of 28 to 70% by weight is heated to a temperature equal to or higher than the cloud point measured using a 10% by weight aqueous solution of the polyether compound, and the polyether compound is the main component. A second step of separating the upper layer, the intermediate layer containing water as a main component, and the precipitated layer (lower layer) of the cutting powder;
And a third step of removing at least a precipitated layer (lower layer) of the cutting powder from the drained oil separated into three layers in the second step.
  In the following general formula (1), R is a hydrocarbon group having 4 to 12 carbon atoms, satisfies the relational expression m ≧ n> 0, and AO is an oxypropylene group (PO). Ingot cutting method. The cloud point measured using a 10 wt% aqueous solution of the polyether compound is 50 ° C or higher,
The ingot according to claim 1 or 2, wherein in the second step, the drained oil is heated to a temperature 5 to 20 ° C higher than a cloud point measured using a 10 wt% aqueous solution of the polyether compound. Cutting method. A method for regenerating a cutting oil composition for a fixed abrasive wire saw used for cutting an ingot,
The cutting oil composition for a fixed abrasive wire saw before use contains 30 to 100% by weight of a polyether compound represented by the following general formula (1),
R—O— (EO) _m (AO) _n —H (1)
(However, R is a hydrocarbon group having 1 to 24 carbon atoms, EO is an oxyethylene group, AO is an oxyalkylene group having 3 or 4 carbon atoms, and m and n are average added moles of EO and AO, respectively. M = 2 to 20 and n = 0 to 20, and the arrangement of EO and AO may be block or random.)
When the water content of the drainage fluid containing the cutting oil composition for the fixed abrasive wire saw after use and the cutting powder of the ingot is not 28 to 70% by weight, the water content of the drainage fluid is A first step of preparing 28-70% by weight;
An oil drainage liquid having a water content of 28 to 70% by weight is heated to a temperature equal to or higher than the cloud point measured using a 10% by weight aqueous solution of the polyether compound, and the polyether compound is the main component. A second step of separating into an upper layer, an intermediate layer containing water as a main component, and a precipitated layer (lower layer) of the cutting powder;
A third step of removing at least a precipitated layer (lower layer) of the cutting powder from the drained oil separated into three layers in the second step; and removing at least the lower layer from the drained fluid in the third step. And a fourth step of adding a polyether compound represented by the general formula (1) and / or water to the residual liquid obtained to obtain a cutting oil composition for a fixed abrasive wire saw. Of reclaiming cutting oil composition.