JPS58192757A - Manufacture of grinding stone made from polyvinyl acetal resin - Google Patents

Abstract

PURPOSE:To make grinding granule retaining property excellent, by impregnating a specific quantity of a suspension comprising grinding granules, a dispersant, and a dispersion medium in a polyvinyl acetal porous body, drying the suspension, and attaching the grinding granules uniformly without cohesion. CONSTITUTION:A PVAt porous body, which is to become a base material of a grinding stone, includes an OH group in a molecule, has excellent hydrophilic and watter absorbing property, and also has a water holding property in a pore configuration having a complicated internal structure. The base material is formed in a shape which is close to the shape of a product. A suspension comprising the following materials is immersed in the base material: (1) grinding granules, which comprise silicon carbide or the like and whose diameter is smaller than 75mum and is desirably less than 16mum; (2) a dispersant, which comprises a polyoxyethylene type or the like, and whose HLB is 11-88 in order to enhance dispersing and suspending effect; and water of a dispersing medium whose main component is water. After a drying process, a PVAt resin grinding stone wherein the grinding granules are uniformly included is obtained. Therefore, the grinding granules and the like are not splashed, working environment is improved, and grinding efficiency becomes excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a novel polyvinyl acetal (hereinafter abbreviated as PVAt) resin grindstone used for mirror finishing of metals, final finishing of optical parts, precision polishing of electronic parts, etc. Its purpose is to create a resin abrasive wheel that does not generate scratches, has excellent abrasive grain retention, and can use a variety of abrasive grains to perform high-precision, high-efficiency polishing. The present invention relates to a manufacturing method.

Conventionally, for curved surface polishing and final polishing of metal materials, non-metallic materials, stone materials, etc., there are two methods: ■ A method using a PVAt-based resin grindstone, ■ A polishing method called lapping or polishing using free abrasive grains, lapping liquid, and lapping cloth 5. ■ Soft polishing method A method using a polyurethane foam to which abrasive grains are attached (Japanese Patent Application Laid-Open No. 126581/1983) is known.

However, each had the following drawbacks.

The PVAt-based resin grinding wheel (3) is made by dispersing and suspending % abrasive grains in a PVAt reaction system consisting of polyvinyl alcohol (hereinafter abbreviated as PVA), aldehyde, acid, and a pore-forming agent], then heating it in a wet state to acetalize it. This grindstone has high elasticity, high continuous porosity, and high abrasive grain rate, which cannot be obtained with other synthetic resin grindstones.

However, with conventional PVA-based resin grindstones, only limited types of abrasive grains can be used because scratches occur, which is thought to be due to agglomeration of the abrasive grains, and an acetalization process is required. There were drawbacks.

Therefore, conventional PVAt resin grindstones are suitable for mirror polishing of stainless steel, copper, aluminum, nickel, etc., final polishing of optical components such as lenses and prisms, and also for semiconductor materials. It is rarely used in fields such as polishing of quartz crystals and sapphire single crystals that require extremely smooth flatness and parallelism to promote epitaxial growth, mirror polishing of silicon for ICs and LSIs, and fine compound semiconductors such as germanium. It was something that had not been done yet.

The polishing method (2) causes a lot of scattering of abrasive grains and lapping liquid, which stains the worker's body and clothes, and adheres to other parts and machines, creating a poor working environment. Since a cloth is used, it is difficult to maintain uniform polishing conditions (polishing pressure, polishing agent concentration, etc.) for a long period of time.Furthermore, since polishing is performed while supplying a mixture of abrasive grains and lapping liquid, it is less likely to scatter at equal pressure. This method has the disadvantage that it is uneconomical because even abrasive grains that do not actually participate in polishing are discarded.

The polishing method (2) had the disadvantage that the abrasive content contained in the flexible polyurethane foam was low, and the compressive strength of the flexible polyurethane foam was low, resulting in poor polishing efficiency.

Therefore, various users have been requesting a PVAt-based resin grindstone that can be used in the above-mentioned fields.

The present invention relates to the above-mentioned improvement of the PVAt resin grindstone.

In (2), this is due to the fact that the framework of each condition such as the degree of abrasiveness, which is the cause of the occurrence of scratches, is determined. If the abrasive grain ratio is the lowest, the agglomeration of the abrasive grains can be alleviated, but in consideration of polishing efficiency, the abrasive grain ratio must be increased, and in this case aggregation of the abrasive grains cannot be avoided. For this purpose 16μ
It is extremely difficult to disperse and suspend ultrafine powder with a particle diameter of less than 100 m without causing agglomeration.

Next, the reason why various types of abrasive grains cannot be used is that in order to obtain a PVAt-based resin grindstone, it is necessary to proceed with the acetalization reaction in a highly concentrated acidic region. However, it was not possible to use abrasive grains that would subtly affect the acetalization reaction and make it difficult to obtain a satisfactory pore shape, and it was inevitably limited to abrasive grains such as fused alumina and silicon oxide. be. Therefore, polishing was performed using abrasive grains that did not suit the purpose of polishing, resulting in poor polishing efficiency. Furthermore, in the conventional method for manufacturing a PVAt-based resin grindstone, there is a large loss of abrasive grains during the manufacturing process, which precludes the use of expensive diamond abrasive grains.

Therefore, as a result of various studies in view of the above-mentioned points, the present inventor succeeded in obtaining the present invention which can achieve the intended purpose.

That is, the first invention stated in the claims is P
After impregnating a certain amount of a suspension consisting of abrasive grains, a dispersant, and a dispersion medium into a porous material based on VA, it is dried and woven with a thread to prevent the abrasive grains from agglomerating into the porous material. This is a method for producing a PVAt-based resin grindstone, which is characterized by uniformly adhering the grindstone. A method for manufacturing a PVAt-based resin grindstone, which is characterized by impregnating the PVAt-based resin with a certain amount and then drying it so that the abrasive grains are uniformly adhered to the PVAt-based porous material without agglomerating them. A PVAt-based porous body is used, and the type of PVA, the size of the pores, the degree of acetalization, etc. are not particularly limited, but can be used as appropriate depending on the purpose of polishing.

Regarding the bulk specific gravity, it is desirable to use one in the range of O, Oa to 0.45 g/n. This is because the PVAt-based porous material used in the present invention needs to have continuous porosity. The continuous porosity is in an inversely proportional relationship such that the smaller the bulk specific gravity is, the greater the continuous complete porosity is. Bulk specific gravity is 0. [lQ
If it is smaller than Δ-, the quality will be unstable, while if the bulk specific gravity is larger than 0.45 f/Cyl, it will not be possible to obtain the continuous porosity necessary for the impregnation of the present invention, which is not preferable. The above range is for satisfying the mechanical strength as a PVAt-based resin grindstone, and the grindstone has sufficient strength without being highly compressed like polyurethane foam.

Next, the reason why pvm-based porous materials are used is that PvAt
The porous material contains many highly hydrophilic OH groups in its molecules, so it has excellent water absorption properties, and its unique pore structure has excellent water retention capacity. It can be said that it is the most suitable resin for This pore form has a complicated internal structure, and when impregnated with a suspension, the abrasive grains are adsorbed to the pore recesses and have the advantage of being effective during polishing operations.

Further pressure, the PVAt porous body used as the base material of the present invention is
The abrasive grains may already be uniformly dispersed and adhered thereto.

It is desirable that the above-mentioned PVAt-based porous body be made into a uniform shape as close as possible to the shape of the intended product in order to reduce loss.

In addition, there are abrasive grains such as PVAt, emery, which was considered unusable due to acid and heating in resin grindstones, and cerium oxide, and cerium oxide is particularly excellent for glass polishing. In addition, it is possible to use expensive abrasive grains, such as diamond and pofzon, which were considered unusable because they flow out during the washing process to remove residual pore-forming agents, acids, aldehydes, etc. after the acetalization reaction, resulting in excellent grinding and polishing. It can be performed. Two or more of these may be used in combination.

Although the method of the present invention can be fully carried out as long as the particle size of the abrasive grains is as small as 75 μm, it is ultrafine powder of 16 μm or less that maximizes the objectives and effects of the present invention.

The abrasive grain ratio can be adjusted arbitrarily by simply changing the abrasive grain concentration in the suspension depending on the purpose of polishing, but conventional fine powder PVAt
It has the characteristic that a high abrasive grain rate of 60 to 90 J, which cannot be obtained with resin based grindstones, can be easily obtained.

Dispersants used in the present invention include nonionic types such as polyoxyethylene type and sorbitan derivatives, anionic types such as sulfonate types, sulfanate types, and phosphate types, and cationic types such as quaternary ammonium salts and imidacillin types. Although any of them can be used, those with an HLB of 11 to 18 are preferred in order to enhance dispersion and suspension effects, and those with an ILB of 11 to 16 are preferred when considering penetration.

The dispersion line of the present invention is required to be water or water-based in order to neutralize the FVAt resin porous body and evenly contain the abrasive grains.

This is because the PVAt resin multi-resin material porous material has a large amount of medium pressure and OH.
When combined with a 1vAt resin porous body, water becomes an optimal carrier and uniformly introduces the abrasive grains into the resin porous body. Also, PV
In the state in which At resin is absorbed into the porous body of polyresin, water acts as a plasticizer, making it extremely flexible and having high compression recovery elasticity. After soaking, the degree of impregnation can be controlled by squeezing rolls, centrifugation, etc. as necessary, and furthermore, by a drying process as a subsequent process,
This is because only water is volatilized without causing magnification of the abrasive grains, and thus a PVAtIM fat abrasive stone in which the abrasive grains are uniformly contained inside the PVAt@fat porous body can be obtained.

In addition, when using a dispersion medium mainly composed of water to which a small amount of a water-soluble organic solvent such as acetone or methyl alcohol is added, the effect is similar to that of a dispersion medium using water, and the drying time is faster. There are some advantages.

The abrasive grains, dispersant, and dispersion medium of the present invention can be made into a suspension by a conventional dispersion method.

Next, in the second aspect of the present invention, an aqueous resin liquid can be mixed into a suspension consisting of abrasive grains, water, and a dispersant. The resin used is a commercially available aqueous solution type or emulsion type.
These include natural polymers such as starch and casein, and various synthetic polymers such as vinyl, acrylic, rubber, urethane, epoxy, and phenol polymers. This strengthens the adhesion between the PVAt porous body and the abrasive grains, and improves the mechanical properties, thermal properties, etc. of the PVAt porous body.

In addition, in the first invention, in order to improve the above-mentioned properties, the suspension may be impregnated and then treated with an aqueous resin or a solution type resin.

A method for impregnating the PVAt porous body with the suspension may be by immersing the PVAt porous body in the suspension, or by impregnating the PVA porous body with the suspension from above.

The PVAt porous body holding a predetermined amount of the suspension is subjected to ordinary hot air drying to remove moisture. Furthermore, when the aqueous resin liquid is used, the temperature and time appropriate for each resin liquid are selected and used.

Since the present invention has the above configuration, it has the following effects.

Since the present invention is a PVAt resin grindstone, there is no scattering of abrasive grains, which improves the working environment. It also makes it easier to manage polishing conditions, and the abrasive grains work effectively, improving polishing efficiency. , became economical.

Compared to the method using flexible polyurethane foam, the present invention provides a product with a high abrasive grain ratio, so it has good polishing efficiency.

In the present invention, a PVAt-based porous body is impregnated with uniformly dispersed abrasive grains, and since the abrasive grains are not aggregated, a pVAt-based resin grindstone that does not cause scratches can be obtained. Furthermore, since no acetalization step is required, any type of abrasive grain can be used, and by using abrasive grains that match the purpose of polishing, it has become possible to perform highly accurate and highly efficient polishing.

In the second invention, since an aqueous resin is added, it is possible to strengthen the adhesion to the PVAt porous path body skeleton, improve various properties, and perform polishing with high efficiency.

Next, the present invention will be explained in detail with reference to Examples.

Example 1 A porous body of PTAt (acetalization degree 78 molti, porosity 89%, bulk specific gravity Q, 14 fl/'CI/), chromium oxide 80# with an average particle size n, s μm, and droxy as a dispersant were added. Ethyl cell a-se (NatrOs manufactured by Herkieless)
O1250H) Impregnated with a suspension consisting of 0.5% aqueous solution io#, dried and molded to obtain a bulk specific gravity of 0.9417Cw.
! A pVAtlJ abrasive stone with an abrasive grain content of $5 wt% and a porosity of 74% was obtained. A sapphire single crystal whose thickness was regulated by rough oving with a 45 μm diamond diamond was semi-finished to a surface roughness of 0.01 to 0.05 μm by lapping with a 3 μm diamond paste. When polished using distilled water, an ultra-precision strain-free surface with a surface roughness of 10<5>- or less and no damaged layer was obtained, which can be used as a substrate for epitaxial growth.

Comparative Example 1. Soft polyurethane foam (porosity 97%, average pore diameter 0.4, bulk specific gravity 0.049) was immersed in the suspension of Example 1, taken out, dried, and molded. , a bulk specific gravity of 0.05 I//Cm, an abrasive grain ratio of 20 vt%, and a porosity of 97. , the surface had a satin surface including cleavage that could be observed with a normal 11M inkstone.It took several times as much polishing time to use it as a substrate.

Example Z pVAt porous body (degree of acetalization 587%, porosity 89%, bulk specific gravity 0.1'4 fl/C1/), Cφ1
500# abrasive grain 76kq, water 180&9, methanol 20
#, Dispersant (Disrol-S manufactured by Nippon Nyukazai Co., Ltd.)
H) After feeding a suspension consisting of 0.8 #, it was dried to remove water.

Next, a resol-type phenolic resin (PR-940, manufactured by Sumitomo Dejima Res Co., Ltd.) was immersed in a methanol solution to remove the resin so that the degree of impregnation (magnet weight after impregnation/weight of grindstone before impregnation) was 1.6. After draining and pre-drying to remove volatiles,
It was heat treated at 150"C and molded to the specified dimensions.
The resin grinding wheel VA' had a bulk specific gravity of 0.67 gΔ7, an abrasive grain ratio of 74 wt%, and a porosity of 71 cm. When a nickel plate (pre-processed C"800 PVAt resin grindstone) was polished with this grindstone, a mirror surface with no scratches was obtained.

, PVAt porous body (degree of acetalization 607%, porosity 91%, bulk specific gravity, 1211/Cd),
Cerium oxide 50# with an average particle size of 1.2 μm, water 120
#, dispersant (Di, 5rO1-8 manufactured by Nippon Nyukazai Co., Ltd.
H) A suspension consisting of 0.48 kg was impregnated and then dried. Next, the solvent type thermosetting acrylic resin (BE-5102 manufactured by San-Ai Rayon Co., Ltd.)! 2chi 1.1.1,
Immersed in trichloroethane solution for 17 minutes, the degree of impregnation is 1.6.
After removing the volatile matter through pre-drying, it is heat-treated at 150°C and molded to the specified dimensions, with a bulk specific gravity of 0.751/ton, an abrasive grain ratio of 77%, and a porosity of 78%. Pv of
An At411Ii fat grindstone was obtained. This luster was obtained.

Example 4 PVAt porous material (degree of acetalization 607%, porosity 91%, bulk specific gravity (Ll 217Cd ), average particle size 1
．． 4 m silconinium oxide 45#, acrylic acid ester resin emulsion (AP-5 manufactured by Showa Kobunshi Co., Ltd.)
0) 2.4#, water 9.6 to 9, dispersant (Disrol H12 manufactured by Nippon Nyukazai Co., Ltd.)! h, After impregnating 5 with a suspension consisting of 4I, water was removed by hot air drying, bulk specific gravity 0,641/Crd, abrasive 1a: 4A 8o
wt%jFc porosity ao qb cy) A PVAt resin grindstone was obtained.

When a silicon wafer was polished using this PVAt grindstone, a scratch-free mirror surface was obtained.

Example A PVAt porous body (degree of acetalization: 527 ruti, porosity: 92%, bulk specific gravity: 0.1297Cd) was molded into predetermined dimensions. A suspension containing 1.5 wt% of diamonds (average particle size 6μ) was prepared in an aqueous urethane resin solution (&5wt), and the core PVAt porous body was impregnated with an amount 48 times the impregnation degree. Then, dry with hot air.

A pVAt resin grindstone (electronic ratio i CL 139/(41, concentration ratio 25, porosity 89%) was obtained.

When polished with a PVAt resin grindstone using distilled water, a surface with particularly excellent flatness and parallelism, with no scratches, and almost no damaged layer was obtained.
It was sufficiently usable as a wafer for Process C.

Example 6 PvAt porous material (degree of acetalization 527 μm, porosity 93 μm, bulk specific gravity 0.09 jJ/Cm') was mixed with silicon carbide having an average particle size of 8 μm and an average particle size of 1.5 μm. Chromium oxide 40kQ, hydroxyethyl cellulose (Harkissushi F! Nat, roso1250 H) 0.5
It was immersed in a suspension consisting of 30 cm of To aqueous solution, and the impregnation degree was 3.
．． After impregnating 8 times the amount, it was dried with hot air to obtain a PVA t resin grindstone (bulk specific gravity: 0.27, abrasive grain ratio: 66W'1.%, porosity: 89cm).

When the surface of a decorative pearl was polished using this whetstone, an extremely high luster with no scratches was obtained.

Patent applicant Nippon Tokushu Kento Co., Ltd. procedural amendment (voluntary) 1. Description of the case 1982 Patent Application No. 76156 2 Name of the invention Method for manufacturing polyvinyl acetal resin grindstone 3 Person making the amendment Relationship to the case Patent applicant 18-4 Kisshoin Oike-cho, Minami-ku, Kyoto City, Amendment 1) Correct the claims in the "Claims" column and "Detailed Description of the Invention" column of the subject specification as shown in the attached sheet.

2) Correct "most" in line 8 of page 5 to "all."

5) On page 5, line U, ``It was at the right point.'' is corrected to ``It was the right thing.''

Page 9, line 14, add ``as described above'' between ``I can do it, but'' and ``conventionally''.

5) Add the following on page 9, line 14, between "...resin grindstone" and "it cannot be obtained with...".

``And other synthetic resin grindstones'' 6) Page 9, No. 14, ``... Abrasive grains'' and ``Gray''
Add "i" between "shitsun...".

7) Add the following and after "..." on page 9, number 14.

There is no particular need to be particular about the degree of impregnation of the rpvht resin porous resin. In other words, as mentioned earlier, PTA resin porous materials have many hydrophilic α-rich OH groups in the molecule, and the pore morphology has a complex internal structure, which makes it difficult to impregnate. This is because, regardless of the value, the abrasive grains do not become migratory or grayish in the drying process after impregnation, and there is little variation in the amount of impregnating liquid deposited within the sample. pyAt
Taking a porous material other than resin, such as urethane foam, if the degree of impregnation is increased due to its pore form, migration of the abrasive grains during drying will be severe. The amount of adhesion of the impregnating liquid within the sample varies widely, and
A high abrasive grain ratio as aimed at by the present invention cannot be obtained. 8) On page n, line 4, "Impregnate..." and "After...
Add the following between ``...''.

9) On the second page, line 5, add the following after “...is good.”

“Resins used here include polyvinyl alcohol, polyvinyl methyl ether, vinyl acetate, acrylic,
Thermoplastic resins such as polyamide, alkyd, saturated polyester, polyurethane, phenoxy, polysulfone, polyallylsulfone, phenol, resorcinol, urea, melamine, furan, epoxy, unsaturated polyester, acrylic, incyanate, silicone, acrylic diester, etc. These include thermosetting resins, thermoplastic SBR, synthetic rubbers such as butyl rubber, polychloroprene, nitrile rubber, and polysulfide.

In order to uniformly adhere these resins to a PTAt resin porous metal body with abrasive grains attached, it is necessary to use a resin dissolved in water or an organic solvent, or an emulsion carbon type resin. .

Organic solvents include aliphatic hydrocarbons such as n-pentane, n-hexane, isobutylene, and turmeric oil, aromatic hydrocarbons such as toluene, xylene, and benzene, methylene chloride, methyl ethyl ketone, and cyclopentanone. Alcohols such as ketones, methanol, ethanol, cellosolve, glycerol, etc., depending on the type of resin11) Between "Compare" and "High abrasive rate..." in the first line of page 13. Add the following and.

"Easily done without the need for compression molding etc." 12) "...high abrasive ratio" and "
Add the following between "The thing is...".

"High density" 13) Page 13, line 14, “...is.

” and then add the following:

"Furthermore, in the second invention, the suspension may be impregnated, dried, and then treated with an aqueous resin or a solvent-based resin.

14) Change “10kg” in the second line of page 14 to “100k
Correct to "g".

15) Page 15, line 3, “...it took a while.

” and the fourth line “Example 2.” Add the following.

A flexible polyester polyurethane foam (30 cells, j, bulk specific gravity 0.[I2) was put into the suspension of Example 1 using a squeezing roll to force the suspension into the urethane foam, and then After removing the liquid from the suspension and using a squeezing roll to remove the liquid so that the degree of impregnation is 3.5, it is dried.
The molded product has an electrical ratio]i0. [14, Abrasive ratio 52.6
wt%, and the porosity was 98%.

Using this whetstone, the pv of Example 1 was obtained under exactly the same conditions as in Example 1.
When it was polished using an At resin grindstone instead, as in Comparative Example 1, it had a matte surface including cleavages that could be observed with a normal microscope. It took several times as much polishing time to use it as a substrate.

Comparative Example & A reticulated polyester polyurethane foam that had been subjected to membrane removal with a number of bubbles of 24/ex and a bulk ratio of 0.035 was placed in the suspension of Example 1 using a squeezing roll to spread the suspension to the inside of the urethane foam. After being forcibly added, it was taken out from the suspension, and the liquid was removed using a squeezing roll so that the degree of impregnation was 5.5, and then dried, and the molded product had a bulk specific gravity of 0.074.
The abrasiveness was 2.6 wt% and the porosity was 96.6%. When this grindstone was used for polishing in place of the PvAt resin grindstone of Example 1 under exactly the same conditions as in Example 1, as in the case of Comparative Example 1, a satin surface state containing cleavage that could be observed with a normal microscope was obtained. there were. It took several times as much polishing time to use it as a substrate.

Comparative Example 4゜The whetstone obtained in Comparative Example 3 was press-molded at 150°C so that the compression ratio (dimension after compression/dimension before compression) was 100, and the bulk specific gravity was 0.89 and the abrasive grain was rate 516wt%,
The porosity was 59.6%. Many scratches deep enough to be observed with the naked eye were observed, indicating that they were polished using a miter whetstone in place of the PVAt resin whetstone of Example 1 under exactly the same conditions as in Example 1. It could not be used as a substrate.

Comparative Example 5゜The grindstone obtained in Comparative Example 3 was compressed to 150 so that the compression ratio was ).
Those press-formed at °C have a bulk specific gravity of 0.30.
The abrasive grain content was 52.6 Wt %, and the porosity was 86.2 cm.

PVA of Example 1 was processed using this whetstone under exactly the same conditions as Example 1.
When polishing was performed instead of using a T-resin grindstone, many deep scratches that could be observed with the naked eye were observed. It could not be used as a substrate. ” Attachment 2, Claim 1, After impregnating a certain amount of a suspension consisting of abrasive grains, a dispersant, and a dispersion medium into a polyvinyl acetal-based polymer, it is dried to form a polyvinyl acetal/ A method for manufacturing a polyvinyl acetal resin grindstone, which is characterized by uniformly adhering abrasive grains to an L'-based porous body without agglomerating them.

2. The method for producing a polyvinyl acetal resin grindstone according to claim 1, wherein the dispersion medium is water or water-based.

A method for producing a ribinyl acetal resin grindstone.

1 Polyvinyl acetal porous material, abrasive grains, dispersant,
It is characterized by impregnating a certain amount of a suspension consisting of a dispersion medium and an aqueous resin and then drying it to agglomerate and evenly adhere the abrasive grains into the polyvinyl aceter/I/based porous material. A method for manufacturing a polyvinyl acetal resin grindstone.

& The method for producing a polyvinyl acecool resin grindstone according to claim 5, wherein the dispersion medium is water or water-based.゛

Claims (1)

[Claims] 1. A polyvinyl acetal porous material is impregnated with a certain amount of a suspension consisting of abrasive grains, a dispersant, and a dispersion medium, and then dried. A method for manufacturing a polyvinyl acetal resin grindstone, which is characterized by uniformly adhering grains without agglomerating them. 2. The method for producing a polyvinyl acetal resin grindstone according to claim 1, wherein the dispersion medium is water or water-based. 3. After impregnating a certain amount of a suspension consisting of abrasive grains, a dispersant, a dispersion medium, and an aqueous resin into a polyvinyl acetal porous material, drying is performed to agglomerate the abrasive grains in the polyvinyl acetal porous material. A method for producing a polyvinyl acetal resin grindstone, which is characterized by uniformly adhering the grindstone without causing any build-up. The method for producing a polyvinyl acetal resin grindstone according to claim 3, wherein the dispersion medium is water or water-based.