JP2000038575A - Aqueous slurry polishing liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aq. slurry polishing liquid which is free of dirt, a bad odor, and a bad influence on human bodies and can easily be washed away even when attached to wire, etc., by dispersing free abrasive grains in an aq, slurry contg. a starch syrup and a dispersant. SOLUTION: This aq. slurry polishing liquid is prepd. by dispersing free abrasive grains in 1l of an aq. slurry contg. 100-300 g of a starch syrup. 100-500 cc of a dispersant, and optionally a rust preventive contg. a low-pH surfactant. A reducing starch syrup, hardly undergoing thermal change in properties and excellent in heat resistance, is pref. as the starch syrup, examples being a highly saccharified reducing starch syrup, a lowly saccharified reducing starch syrup, and a reducing maltose starch syrup. The dispersant is cellulose microfibers having a thickness of 0.1-0.01 μm and prepd. by applying a strong mechanical shearing force to highly purified plant fibers with an ultrahigh-pressure homogenizer, The aq. slurry polishing liquid is used for wire cutting with a wire saw, and the dispersion stability of the abrasive grains and the attachability thereof give good results.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous slurry polishing liquid, and more particularly to an aqueous slurry polishing liquid used in a processing apparatus such as a wire saw, wherein free abrasive grains are dispersed in the aqueous slurry liquid.

[0002]

2. Description of the Related Art In general, there is a wire saw as a processing apparatus for cutting a workpiece such as an ingot made of a hard and brittle material such as silicon for semiconductors, ceramics and quartz (quartz) into many pieces at a time. This wire saw presses a large number of wires stretched to a predetermined tension against a work, and cuts the work by the abrasive action of abrasive grains while reciprocating the wires.

[0003] The abrasive grains used in the cutting process using the wire saw are sometimes fixed to the wire (fixed abrasive method), but they are dispersed in oil or water and used as an oily or aqueous slurry polishing liquid ( Loose abrasive method). In this loose abrasive method, an oil-based slurry polishing liquid is generally used in general because it is easy to adjust the fluidity. Further, in the case of an aqueous slurry polishing liquid in which abrasive grains are dispersed in water, a large amount of glycerin is contained in order to increase the viscosity and enhance the dispersion retention of the abrasive grains.

[0004]

However, in the case of an oily slurry polishing liquid in which abrasive grains are dispersed in oil, the used liquid must be treated as industrial waste and cannot be drained into general wastewater. The cutting device becomes dirty due to the slurry polishing liquid scattered during processing and the odor due to oil mist is intense.
Furthermore, when the slurry polishing liquid directly adheres to the skin, it causes a problem such as itching, which has a problem of adversely affecting the human body.

On the other hand, in the case of an aqueous slurry polishing liquid in which abrasive grains are dispersed in water, there is no dirt, odor or adverse effect on the human body of the cutting device described above, and even if it adheres to a wire or the like, it can be easily washed off. Although it is easy to recycle the abrasive grains, it is usually necessary to take sufficient care in handling a large amount of glycerin in combination with the use of glycerin. There was a problem that it was necessary to treat and it was not possible to drain to general wastewater.

Accordingly, the present invention has been proposed in view of the aforementioned problems, and an object of the present invention is to provide an aqueous slurry based on a material containing no harmful substances so that it can be drained to general wastewater. It is to provide a polishing liquid.

[0007]

As a technical means for achieving the above-mentioned object, the present invention relates to a method in which free abrasive grains are added to an aqueous slurry liquid containing edible syrup and a dispersant for cellulose fibers. It is characterized by being dispersed. Specifically, reduced starch syrup is suitable as the starch syrup,
Microfibrous cellulose is suitable as a dispersant. still,
The aqueous slurry polishing liquid of the present invention can be used for work cutting by a wire saw.

In the present invention, since the aqueous slurry containing the syrup and the dispersant is used, there is no dirt, bad smell or adverse effect on the human body, and even if it adheres to a wire or the like, it can be easily washed off. Abrasives can be easily recycled and can be drained into general wastewater because they do not contain harmful substances.

For example, when applied to a wire saw, the necessary conditions include that the dispersion stability of the abrasive grains is high so that the concentration of the abrasive grains dispersed in the aqueous slurry liquid is constant, May have good adhesion.

[0010] Assuming that these conditions are satisfied, in the aqueous slurry liquid of the present invention, syrup exhibits an effect of increasing the viscosity of the aqueous slurry liquid and an effect of improving the adhesion of the abrasive grains to the wire. By using fibrous cellulose, the effect of enhancing the dispersion stability of the abrasive grains is exhibited by a synergistic effect with the aforementioned syrup.

In the present invention, 100 g of starch syrup and 100 g of dispersant are contained in 1 liter of aqueous slurry liquid.
It is preferable to mix at a ratio of 500 cc because the effect of increasing the viscosity of the aqueous slurry liquid, the effect of improving the adhesion of the abrasive grains to the wire, and the effect of increasing the dispersion stability of the abrasive grains can be sufficiently exhibited. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the aqueous slurry polishing liquid according to the present invention will be described in detail below. In the following embodiments, a processing apparatus using a loose abrasive method, for example, a case where the present invention is applied to a wire saw will be described.However, the present invention is not limited to this, and may be applied to other processing apparatuses such as a lapping apparatus and a polishing apparatus. Is also applicable.

The aqueous slurry polishing liquid of this embodiment is obtained by dispersing free abrasive grains in an aqueous slurry liquid, and comprises a syrup, a dispersant and, if necessary, a rust inhibitor, for example, ion-exchanged water or the like. An aqueous slurry liquid dispersed in a water-soluble solvent is used. The use of the aqueous slurry containing the starch syrup and the dispersant as described above eliminates dirt, odors and adverse effects on the human body. It can be easily converted to general wastewater because it does not contain harmful substances.

For example, when the aqueous slurry polishing liquid of the present invention is used in a workpiece cutting process using a wire saw, the dispersion stability of the abrasive particles is high so that the concentration of the abrasive particles dispersed in the aqueous slurry liquid is constant. Also, a condition is required in which the adhesion of the abrasive grains to the wire is good. Under these conditions, the syrup blended in the aqueous slurry liquid of the present invention exhibits a thickening effect of the aqueous slurry liquid and an effect of improving the adhesion of the abrasive grains to the wire, and has a synergistic effect with the dispersant. Thereby, the effect of enhancing the dispersion stability of the abrasive grains is exhibited, and a lubricating effect at the time of cutting the work is exhibited.

There are many types of starch syrup, and various types can be used as long as the above-mentioned effects can be obtained. However, the reduced starch syrup has a small property change due to heat and is excellent in heat resistance. It is desirable to use For example, as reduced starch syrup obtained by decomposition of starch,
There are a high-saccharified reduced starch syrup, a low-saccharified reduced starch syrup, a reduced maltose starch syrup, and the like. Particularly, a low-saccharified reduced starch syrup is suitable.

As the dispersant, microfibrous cellulose is preferable. This microfibrous cellulose is made from highly purified pure plant fiber as a raw material, and is subjected to a strong mechanical shearing force by an ultra-high pressure homogenizer to form a microfibrillated fiber. It is torn into ten thousand pieces and the thickness of the fiber is 0.1-0.01μm
It has been miniaturized. Due to the miniaturization, the surface area of the fiber is dramatically increased, so that the hydrophilicity, which is the inherent characteristic of cellulose, is remarkably enhanced, and entanglement between the microfibers is caused. Shows viscosity stability and dispersion stability.

For example, a cellulose fiber solid content of 1.2 in water
By using the one containing 7% as a dispersant, the abrasive grains are retained in a network structure by entanglement of the microfibrous cellulose, and excellent dispersion stability is obtained. Note that the microfibrous cellulose serves as a buffer between the wire and the work when the work is cut, thereby preventing cracks in the work.

Further, as the rust preventive, those containing a low pH surfactant in water are preferred.

In the present invention, 100 g of starch syrup and 100 g of dispersant are added to 1 liter of the aqueous slurry liquid.
It is preferable to mix at a ratio of 500 cc because the effect of increasing the viscosity of the aqueous slurry liquid, the effect of improving the adhesion of the abrasive grains to the wire, and the effect of increasing the dispersion stability of the abrasive grains can be sufficiently exhibited. .

If the syrup is less than 100 g, the thickening effect of the aqueous slurry liquid and the good adhesion of the abrasive grains to the wire cannot be obtained.
If it is more than 0 g, the viscosity becomes too high and the fluidity becomes poor. On the other hand, if the dispersant is less than 100 cc, the abrasive grains cannot be sufficiently dispersed in the aqueous slurry liquid.
If the amount of the dispersant is more than 500 cc, the viscosity becomes too high as in the case of starch syrup, and the fluidity becomes poor.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to confirm the cutting ability of the aqueous slurry polishing liquid according to the present invention, the applicant measured the cutting amount of a work using an experimental apparatus shown in FIGS. The cutting abilities of the oily slurry polishing liquid of Example 1 and the aqueous slurry polishing liquid of the present invention were compared.

The experimental apparatus shown in FIGS. 1 (a) and 1 (b)
The work 3 is linearly reciprocated by the AC servomotor 1 via the ball screw 2. The work 3 is cut by pressing the wire 5 stretched with a predetermined tension by the weight 4 against the reciprocating work 3. During this cutting, a slurry polishing liquid is supplied from a supply nozzle 6 which reciprocates together with the work 3.

The cutting speed of this wire is 140 mm
The workpiece is cut with a wire while a fixed amount of slurry polishing liquid is supplied from a supply nozzle by a constant-rate pump with the number of reciprocations set to 100 times / s. The work is made of silicon and the cut amount of the work is 3
Measured times.

A conventional oily slurry polishing liquid is composed of 180 g of abrasive grains (GC # 800) in 140 ml of the oily slurry liquid.
Was used. The results are as follows.

(Before cutting) (After cutting) (Cutting amount) First time 16.9283g-16.9054g = 0.0229g Second time 16.9054g-16.8913g = 0.0141g Third time 16.8913g-16.8608g = 0.0305g (Average cutting amount 0.0229g) g) As the aqueous slurry polishing liquid of the present invention, an aqueous slurry liquid in which 180 g of abrasive grains (GC # 800) were dispersed in 180 ml of the above-described aqueous slurry liquid was used. The results are as follows.

(Before cutting) (After cutting) (Cutting amount) First time 16.9374g-16.8983g = 0.0391g Second time 16.8983g-16.8775g = 0.0208g Third time 16.8775g-16.8543g = 0.0232g (Average cutting amount 0.0277 g) As is clear from the above comparison results, it was also found that the product of the present invention has sufficient cutting ability with the aqueous slurry polishing liquid in comparison with the cutting ability with the oily slurry polishing liquid of the conventional product.

Further, as a result of observing the wire after cutting with a microscope and comparing the state before and after the wire cleaning, as shown in FIG. Aqueous slurry polishing liquid of the product of the present invention [see FIG.
It is clear that the larger the amount of the abrasive particles attached to the wire, the better the adhesion of the abrasive particles to the wire. On the other hand, after the wire cleaning, the abrasive grains of the aqueous slurry polishing liquid of the present invention (see FIG. (D)) are easier to form than the conventional oil-based slurry polishing liquid (see FIG. (B)). It is clear that it has been washed away and its adhesion amount is small and sufficiently removed.

Further, the results obtained by analyzing the components of the aqueous slurry polishing liquid of the product of the present invention by subjecting the used slurry liquid to a recovery machine and analyzing the components are shown in the following table.

[0029]

[Table 1]

In the above table, the component content of the stock solution itself (values in the left column) exceeds the reference value for drainage (values in the right column) (S
By diluting (excluding S and total phosphorus) with a suitable non-hazardous solvent such as water, the wastewater standard value can be cleared and drainage to general wastewater becomes possible. In the example of the above table, draining to general wastewater is possible if the dilution is performed at a dilution ratio of 667 times or more.

[0031]

According to the aqueous slurry liquid of the present invention, since the syrup exhibits the effect of thickening the aqueous slurry liquid and the effect of improving the adhesion of the abrasive grains to the wire, it is equal to or more than the conventional oil-based slurry liquid. The above processing ability can be maintained. In addition, since it is based on edible material such as water syrup, there is no adverse effect on the human body, and if diluted with water, it can be drained to general waste water. Further, the abrasive grains can be easily recycled because they can be easily washed with water.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram showing an experimental device used in an embodiment of the present invention. FIG. 1B is an enlarged view of a part A of the experimental device in FIG.

FIG. 2A is an enlarged view showing a surface state of a wire with a conventional oily slurry polishing liquid (before cleaning), and FIG. 2B is a view showing a surface state of the wire with a conventional oily slurry polishing liquid (after cleaning). The enlarged view (c) shows the surface state of the wire of the present invention with the aqueous slurry polishing liquid (before washing), and the enlarged view (d) shows the surface state of the wire of the present invention with the aqueous slurry polishing liquid (after washing). Enlarged view

Claims (4)

[Claims] An aqueous slurry polishing liquid characterized by dispersing free abrasive grains in an aqueous slurry liquid containing a syrup and a dispersant. 2. The aqueous slurry polishing liquid according to claim 1, wherein the syrup is a reduced syrup. 3. The aqueous slurry polishing liquid according to claim 1, wherein the dispersant is fibrous cellulose. 4. The aqueous slurry polishing liquid according to claim 1, which is used for cutting a workpiece with a wire saw.