JP2001088036A - Resinoid whetstone - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a grindstone of a resinoid grindstone with improved workability in manufacturing and improved water resistance, heat resistance and high strength. SOLUTION: The binder comprises a powdered phenolic resin and a liquid resin, and the liquid resin contains a furfuryl alcohol-furfural co-condensation oligomer or a furfuryl alcohol condensed oligomer of 3% by weight or more and a curable resin having a nonvolatile content of 30% by weight or more. Is a resinoid whetstone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resinoid grindstone, and more particularly to a resinoid grindstone for grinding, polishing, and cutting, which requires improved workability, water resistance, heat resistance, and high strength in the production of a grindstone. is there.

[0002]

2. Description of the Related Art Resinoid grindstones mix abrasive grains with a liquid resin or a solvent to wet the abrasive grains, and then knead a powdered phenolic resin and, if necessary, additives such as cryolite or iron sulfide or other grinding aids. As a result, an intermediate product called a coated grain in which the resin particles are uniformly coated on the abrasive grains is produced, and the intermediate product is manufactured by press molding and firing.

[0003] As the liquid resin, a liquid phenol resin has been generally used. In order to further increase the adhesive strength between the abrasive grains and the resin binder and improve the water resistance, heat resistance and strength, furfuryl alcohol and furfural are added to the liquid phenol resin as furan-based solvents (Japanese Patent Laid-Open No. 57-57). No. 27667) or using furfuryl alcohol or furfural as a furan-based solvent instead of a liquid phenol resin. However, since these solvents have too high a solubility in the powdered phenolic resin, there are disadvantages that the viscosity is excessively increased at the time of kneading the powdered phenolic resin and that the coated grains are liable to cause blocking.

[0004] If the increase in viscosity during the kneading of coated grains and the blocking of coated grains occur, the working time in the production of coated grains and press molding becomes longer,
Workability at the time of whetstone production deteriorates. Therefore, the use of a liquid phenol resin having low solubility has been studied, but there is a problem that the water resistance, heat resistance and strength of a whetstone cannot be improved.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to increase the adhesive strength with abrasive grains, add water resistance, heat resistance and high strength to a grindstone, and knead and mix powder phenol in the production of coated grains. It is an object of the present invention to provide a resinoid grindstone in which the coated grain is less likely to be affected by environmental conditions and is in an appropriate state, so that the workability during the production of the grindstone is good.

[0006]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies, and as a result, the binder comprises a powdered phenolic resin and a liquid resin, and the liquid resin is co-condensed with furfuryl alcohol-furfural. 30% by weight or more of a nonvolatile content containing 3% by weight or more of an oligomer or a furfuryl alcohol condensed oligomer (The measurement method is JIS K6
909) was found to improve the above-mentioned properties, and based on this knowledge, various studies were conducted to complete the present invention.

The phenol resin powder used in the present invention is usually a powder having an average particle diameter of 100 μm or less, preferably a powder having an average particle diameter of 10 to 40 μm, and preferably a phenol resin having a melting point of 60 to 120 ° C. is there.

The powdered phenolic resin is generally a novolak type phenolic resin formed of phenol and formaldehyde with an acid catalyst and a resin containing hexamethylenetetramine as a curing agent in an amount of 3 to 20% based on the phenolic resin. A resol type phenol resin produced by a catalyst or a mixture thereof may be used.
Further, a phenol resin using phenols such as cresol, xylenol, para-tert-butylphenol, resorcin, and bisphenol A alone or in combination can also be used. In addition, rosin-modified phenolic resin, rubber-modified phenolic resin, polyimide-modified phenolic resin, epoxy-modified phenolic resin, phenoxy-modified phenolic resin, cashew-modified phenolic resin,
Oil-modified phenolic resin, urethane-modified phenolic resin,
Various modified phenol resins such as a silicone-modified phenol resin, an alkyl-modified phenol resin, a boric acid-modified phenol resin, a polyamide-modified phenol resin, an alkyl-modified phenol resin, and an aralkyl-modified phenol resin may be used.

The liquid resin is a curable resin such as a furfuryl alcohol-furfural co-condensation oligomer or a furan resin, a phenol resin or an epoxy resin containing at least 3% by weight of a furfuryl alcohol condensation oligomer,
It usually contains unreacted monomers such as furfural, furfuryl alcohol and phenol, or organic solvents and water. The furfuryl alcohol-furfural co-condensation oligomer or the furfuryl alcohol condensed oligomer referred to herein is furfuryl alcohol and furfural, or furfuryl, or a furfuryl alcohol obtained by reacting only furfuryl alcohol with a known method using an acid or alkali catalyst. An oligomer compound in which two or more rings are bonded.

The curable resin is a three-dimensionally cross-linked oligomer such as a phenolic resin, a furan resin, an epoxy resin, an amino resin, and a urea resin. From the viewpoint of workability or strength, a phenolic resin or a furan resin is used. preferable.

The content of the furfuryl alcohol-furfural co-condensation oligomer or the furfuryl alcohol condensation oligomer in the liquid resin is 3% by weight or more. If the content is less than 3% by weight, the effect of improving the strength is difficult to obtain, which is not preferable. Further, even if it exceeds 10% by weight, its effect does not change, so it is usually set to 10% by weight or less.

The nonvolatile content of the curable resin is at least 30% by weight. When the content of unreacted monomers such as furfural, furfuryl alcohol and phenol, organic solvents and water is 70% by weight or more,
Since the solubility of the powdered resin is increased, the workability of the coated grains is adversely affected, and the volatile components at the time of firing the grindstone are large, which adversely affects the product. The upper limit of the non-volatile content is desirably increased in a range where the non-volatile content increases and the viscosity is increased so that the mixing property is not impaired.
The viscosity in a range that does not impair the mixing property cannot be determined unconditionally in order to adjust the resin viscosity depending on the working environment and the capacity of the kneading machine, but the resin viscosity is desirably 0.1 to 2.0 Pa · s / 25 ° C. No limitation. In consideration of these points, the upper limit of the non-volatile content depends on the volatile component, but is 50 to 8%.
0% by weight.

The abrasive grains include aluminum oxide, silicon nitride, silicon carbide, alumina-zirconia, abrasive grains mainly composed of alumina by a sol-gel method, cerium oxide,
Garnet, diamond, cubic boron nitride, etc., alone or in combination. Also, if necessary, other additives,
For example, cryolite, potassium borofluoride, polishing aids such as iron sulfide, calcium carbonate, silicon oxide, fillers such as talc,
A pore forming agent such as ceramic hollow spherical ceramic fine particles, a pigment for coloring, a dye, and the like may be added.

The method and ratio of blending the powdered phenolic resin and the liquid resin are the same as those in the conventional method and are not particularly limited. Similarly, the ratio between the abrasive grains and the resin amount is not particularly limited. In the mixing and kneading of the liquid resin, different curable resins, solvents, and the like may be charged in several times, and as a result, the liquid resin according to the present invention may be obtained. Since the liquid resin is for the purpose of increasing the adhesive strength with the abrasive grains, it is preferable to first knead the abrasive grains with the liquid resin and wet the abrasive grains with the liquid resin. The method for forming the resinoid grindstone and the firing are not particularly limited.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. “Parts” and “%” described herein are all indicated as “parts by weight” and “% by weight”.

(Example 1) PR-940 (phenol resin manufactured by Sumitomo Durez Co., Ltd., resin viscosity = 0.4 Pa · s)
/ 25 ° C, nonvolatile content 70%) FR-1647 in 100 parts
20 (Furan resin manufactured by Sumitomo Durez Co., Ltd.) was added, and a liquid resin A (0.4 Pa · s / 25 ° C., nonvolatile matter 68) was added.
% Furfuryl alcohol-furfural co-condensation oligomer 8%). 1000 parts of abrasive grain Sacrundum A # 60 (alumina abrasive grains manufactured by Nippon Carlit Co., Ltd.) and 20 parts of liquid resin A were kneaded with a kneader for 3 minutes. Into another kneader, 120 parts of PR-50252 (Powder phenol resin manufactured by Sumitomo Durez Co., Ltd.) was previously charged, and a kneaded product of abrasive grains and a liquid resin was added and kneaded to obtain a coated grain. This was press-molded at a molding specific gravity of 2.4, placed in a firing furnace, and heated to 170 ° C. over 25 hours.
After maintaining for 0 hours, the mixture was gradually cooled to obtain a resinoid grindstone test piece.

Example 2 PR-940 (Phenol resin manufactured by Sumitomo Durez Co., Ltd., resin viscosity = 0.4 Pa · s /
(25 ° C, 70% non-volatile content) FR-16475 in 100 parts
(Furan resin manufactured by Sumitomo Durez Co., Ltd.) was added in an amount of 100 parts, and a liquid resin B (0.4 Pa · s / 25 ° C., nonvolatile content 61) was added.
%, Furfuryl alcohol-furfural co-condensation oligomer 25%). Abrasive grain Sakurandom A # 60
1000 parts (alumina abrasive grains manufactured by Nippon Carlit Co., Ltd.) and 20 parts of liquid resin B were kneaded with a kneader for 3 minutes. Into another kneader, 120 parts of PR-50252 (Powder phenol resin manufactured by Sumitomo Durez Co., Ltd.) was previously charged, and a kneaded product of abrasive grains and a liquid resin was added and kneaded to obtain a coated grain. Thereafter, molding and firing were performed in the same manner as in Example 1 to obtain a resinoid grindstone test piece.

Comparative Example 1 Sumilite resin PR-940 (phenol resin manufactured by Sumitomo Durez Co., Ltd.) as a liquid resin, resin viscosity = 0.4 Pa · s / 25 ° C., nonvolatile content 70
%) And 1000 parts of Abrasive Grain Sacrundum A # 60 (alumina abrasive grains manufactured by Nippon Carlit Co., Ltd.) and 22 parts of Sumilite Resin PR-940 were kneaded with a kneading machine for 3 minutes. Into another kneading machine, 118 parts of PR-50252 (powder phenol resin manufactured by Sumitomo Durez Co., Ltd.) was previously charged, and a kneaded product of abrasive grains and a liquid resin was added and kneaded to obtain a coated grain. Thereafter, molding and firing were performed in the same manner as in Example 1 to obtain a resinoid grindstone test piece.

Comparative Example 2 PR-940 as a liquid resin
0 (phenol resin manufactured by Sumitomo Durez Co., Ltd., resin viscosity =
Using 0.2 Pa · s / 25 ° C., a non-volatile content of 60%, and furfural of 10%), 1000 parts of abrasive sakurandom A # 60 (alumina abrasive made by Nippon Carlit Co., Ltd.) and Sumilite Resin PR-940016 The mixture was kneaded with a kneader for 3 minutes. Into another kneader, 124 parts of PR-50252 (powder phenol resin manufactured by Sumitomo Durez Co., Ltd.) were previously charged, and a mixture of abrasive grains and a liquid resin was added and kneaded to obtain a coated grain. After that, Example 1
In the same manner as described above, a resinoid grindstone test piece was obtained.

(Comparative Example 3) Furfuryl alcohol was used in place of the liquid resin, and kneaded, molded and fired in the same manner as in Example 1 to obtain a resinoid grindstone test piece. Abrasive grain Sakurandom A # 6
1000 parts (alumina abrasive grains manufactured by Nippon Carlit Co., Ltd.) and 13 parts of furfuryl alcohol were kneaded with a kneader for 3 minutes. Into another kneader, 127 parts of PR-50252 (Powder phenol resin manufactured by Sumitomo Durez Co., Ltd.) are previously charged, and 20 parts of a mixture of abrasive grains and a liquid resin are added and kneaded to obtain a coated grain. Was. Thereafter, molding and firing were performed in the same manner as in Example 1 to obtain a resinoid grindstone test piece.

Table 1 shows the results of comparing the normal strength and water resistance of resinoid grindstone test pieces as evaluations of workability during coated grain production, coated grain blocking properties, and grindstone strength. Shown in

[0022]

[Table 1]

[Measurement method] Workability Workability during coated grain production was evaluated according to the following criteria. ：: Good flowability of coated grains △: Good flowability of coated grains, but small lumps blocked ×: Blocking and poor flowability of coated grains Blocking property 50g of coated grain at 25 ° C and 60% humidity
For 24 hours, placed on a 20 mesh sieve, sieved with a vibration sieve for 20 seconds, and measured the weight (g) remaining on the sieve. 3. 3. Normal strength Grindstone test piece size 100 × 25 × 10mm Bending strength at normal temperature, span 80mm, head speed 2mm / min. 4. Water resistant strength Whetstone test piece size 100 × 25 × 10 mm 40 ° C. After immersion in water for 3 days Bending strength at room temperature, span 80 mm, head speed 2 mm / min 5. Heat resistance Grindstone test piece size 100 × 25 × 10mm Flexural strength at 250 ° C, span 80mm, head speed 2mm / min

As is clear from Table 1, Examples 1 and 2
Both have good workability at the time of manufacture of a grindstone and also have a high grindstone strength. On the other hand, Comparative Example 1 is good in workability but low in strength, since it is a phenol resin only and does not contain furfuryl alcohol-furfural co-condensation oligomer or furfuryl alcohol condensed oligomer. Comparative Example 2 not containing the oligomer but containing a furan-based solvent
In Nos. 3 and 3, although the strength is high, the workability is poor.

[0025]

As described above, the resinoid grindstone of the present invention has improved workability at the time of manufacture of the grindstone, and has excellent water resistance, heat resistance and high strength of the grindstone, thereby improving the grindstone productivity and the grindstone grinding performance. It is expected that both will contribute.

Claims (1)

[Claims] 1. A resinoid grindstone containing abrasive grains and a resin binder, wherein the resin binder comprises a powdered phenol resin and a liquid resin, and the liquid resin is furfuryl alcohol-furfural co-condensation oligomer or furfuryl alcohol condensation oligomer. A resinoid grindstone characterized by being a curable resin having a nonvolatile content of 30% by weight or more, containing at least 30% by weight.