JPS60137981A - Binder for grinding whetstone - Google Patents

Abstract

PURPOSE:To obtain a binder for precision grinding whestone, of high water, alkali and heat resistance, rigidity and whetstone powder sticking power, by imcorporating epoxy resin, novolak-type phenolic resin as curing agent and reaction promotor in whetstone powder. CONSTITUTION:The objective binder can be obtained by incorporating whetstone powder with (A) epoxy resin (e.g. epichlorohydrin bisphenol A-type epoxy resin), (B) novolak-type phenolic resin as curing agent for the component (A) and (C) a reaction promotor (e.g. hexamethylenetetramine) followed by forming, calcination and curing. Preferably, the equivalent ratio of the epoxy group of the component (A) to the active hydrogen in the component (B) is 1/0.8-1/1.1, and the amount of the component (C) is 0.1-1pt.wt. per 100pts.wt. of the components (A) plus (B).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a binder for grinding wheels having excellent water resistance and alkali resistance, and mainly to a binder for precision grinding wheels.

Grinding wheels are made by fixing a large number of obtuse-angled abrasive grains with a bonding agent.
The desired grinding and polishing process is performed by simultaneous grinding. Generally required properties of binder are U:,
It has high rAll properties, strong abrasive grain adhesion, withstands 9g of impact during cutting, and does not deform or fuse to the workpiece surface due to grinding heat. Conventional binders that are susceptible to deterioration due to ill removal include vitrified binders, magnesia cement, and other binders, as well as organic binders such as rubber, phenolic resin, and polyvinyl alcohol. Among these, phenol-17 sebum-based binders have been widely used due to their good workability and heat resistance, but they have the disadvantage of poor water resistance and alkali resistance. As a result of intensive research in order to obtain an organic binder that does not have such drawbacks, we found that by crosslinking epoxy resin and novolac type phenolic resin, we have developed a material that has excellent heat resistance, rigidity, and abrasive adhesion, as well as water resistance and alkali resistance. The present invention was completed based on the discovery that an excellent grinding wheel could be obtained.

That is, the present invention provides a bonding agent for a grinding wheel, which is characterized by containing an epoxy resin, a 7-borac type phenolic resin, and a reaction accelerator.

Conventionally, for phenol (I54) fat-based bonding for this purpose, it has been common to react formaldehyde at the ortho and distal positions of phenol to polymerize it, and novolac-type phenol (a (The fat has been thermally cured by using hexamethylenetetramine as a crosslinking agent, or by the methylol groups remaining in the resol type phenolic resin t obtained under alkaline conditions.In contrast, the present invention Novolac-type phenol (σ) is a product in which the novolak-type phenol resin is thermally crosslinked by using an epoxy resin and a small amount of reaction accelerator, and the heat resistance due to the novolak structure is ,1
It has both the water resistance and alkali resistance of epoxy resin, and it also has the advantage of being completely cured at a lower temperature than the conventional mixed powder of novolak type phenol resin and hexamethylenetetramine. The epoxy resin used in the present invention is a generally known epoxy resin, such as an epichlorohydrin-bisphenol A type epoxy resin obtained by reacting epichlorohydrin with bisphenol A, a novolac type phenol resin, or a cresol resin obtained by reacting epichlorohydrin. and polyfunctional epoxy resins such as liquid epoxy resins obtained by reacting glycols toepichlorohydrin. These polyfunctional epoxy resins can also be used in combination with primary epoxy compounds such as monoglycidyl ethers.

In addition, the novolac type phenolic resin used as a curing agent for epoxy resins includes phenols such as phenol, paratertiary butylphenol, secondary butylphenol, paraoctylphenol, and cresols such as orthocresol, metacresol, and paracresol. Novolac type phenolic resins obtained by reacting two or more types with formaldehyde, and those having phenolic hydroxyl groups, are mentioned.

Furthermore, as the reaction promoter, imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole, and amines such as dimethylbenzylamine, triethylamine, and triethanolamine can be used. Hexamethylenetetramine, which is used as a crosslinking agent for novolac-type phenolic resin, can be used as a reaction accelerator because the amine derivative decomposed and produced during the curing reaction accelerates the curing of the epoxy resin and novolak-type phenolic resin.

The ratio of the epoxy resin and novolac type phenol resin used in the present invention is such that the ratio of the epoxy equivalent of the epoxy resin to the active hydrogen equivalent of the novolak type phenol resin is 07 to
The ratio is 1:15, preferably 1:08 to 1:11.

The amount of reaction accelerator added is 100 parts by weight of the epoxy resin and novolak type phenol resin.
The amount is usually 0.05 to 4 parts by weight, preferably 0.1 to 1 part by weight.

Conventional methods can be applied to produce a grinding wheel using the binder of the present invention. A binder containing a reaction accelerator is mixed with 100 parts by weight of the abrasive grains at a ratio of usually 10 to 60 parts by weight, preferably 15 to 30 parts by weight, to form resin-mixed abrasive grains, which are then mixed with gold. Fill into the mold and set the mold temperature to 10~
After molding at 100℃ and a pressure of 0.5 to 50 kg/m', it is baked stepwise or continuously to 140 to 200℃ to fully harden the binder, and then ground. A whetstone is obtained.

Examples are shown below. However, none of these limits the present invention in any way. In addition, % in an example is weight %.

Example 1 Novolac type phenolic resin Product name: Barcam TD-2
090 [Softening point 95℃ Dainippon Ink and Chemicals (4'lW
J') and polyfunctional epoxy 41'Tl resin (trade name: Epiclon 4050 [softening point: 100°C, manufactured by Dainippon Ink & Chemicals, Ltd.) in a ratio of active hydrogen equivalent to epoxy equivalent of 1:1. , and pulverized to obtain powdered resin.

was added and mixed uniformly. Furthermore, 160 g of the powdered resin obtained above was added and mixed uniformly to obtain resin-mixed abrasive grains.

This mixed abrasive grain is filled in the mold t/% temperature 60℃, pressure 2
After molding under the conditions of 0 kg/'cIn2, it was baked at 80°C for 4 hours, 120°C for 4 hours, and 180°C for 2 hours.
A cutting wheel and a test piece having a thickness of 0HyJ and a thickness of 3 mm were obtained. This grindstone was excellent in heat resistance, rigidity, abrasive grain adhesion, water resistance, and alkali resistance.

Example 2 Novolac type phenolic resin Product name Percam TD-2
090 and polyfunctional epoxy resin Product name Evicron N-
775 [Softening point 75°C, Dainippon Ink and Chemicals (4fJ
? ,'! 1 and 1 were mixed and pulverized in such a ratio that the ratio of active hydrogen equivalent to epoxy resin was 0:09 to obtain a powdered resin.

Abrasive grain Product name Safrandom A430 1 per 1.000g
% 2-methylimidazole water-methanol mixed solution 8
g was added and mixed uniformly. Furthermore, 160 g of the powdered resin obtained above was added and mixed uniformly to obtain resin-mixed abrasive grains. This mixed abrasive grain was molded and fired in the same manner as in Example 1 to obtain a cutting wheel and test piece with a 405mm diameter and 3mm thickness. This stone No. 41 was excellent in heat resistance, rigidity, abrasive grain adhesion, water resistance, and alkali resistance.

Comparative Example 1 Abrasive grains: Product name: Zakurandom 130 1.000g Resol type phenolic resin: Product name: Pryophen TD-
2361 [Dainippon Ink Chemical Industry! 4'HW 140.
9 was added and mixed uniformly, 120 g of hexamethylenetetramine-containing powdered novolac type phenol resin, trade name Pryophen TD-2112 (manufactured by the same company) was added and mixed uniformly to obtain resin-mixed abrasive grains. Using this mixed abrasive grain, it was molded and fired in the same manner as in Example 1 to obtain a cutting whetstone of 405 ml and a thickness of 3 mm and a test piece. This whetstone had poor water resistance and alkali resistance.

Test Example 1 The bending strengths of the test pieces obtained in Examples 1 to 2 and Comparative Example 1 were compared, and the results shown in Table 1 were obtained.

Table 1 Note) 1) Boiling the test piece in boiling water for 2 hours 2) Immersing the test piece in a 5% caustic soda aqueous solution for 2 hours and washing with water Also, the grindability of the obtained cutting wheels was compared. Noyo Table 2 Work material 50mm 5S-41 round bar Note) 1) Soak the cutting wheel in water at 20°C for 24 hours.

2) Average time required for each cut when the above rigid material was cut 5 times.

3) Amount of wear on the grindstone when cutting the above rigid material 5 times.

Agent: Patent Attorney Katsutoshi Takahashi

Claims (1)

[Claims] A bonding agent for grinding wheels characterized by containing an epoxy resin, a novolac type phenolic resin, and a reaction accelerator.