JPS61197164A - Synthetic grindstone and its production method - Google Patents

Abstract

PURPOSE:To obtain a resinoid synthetic grindstone having excellent smoothness and a high void ratio by adding grindstone particles, a pore formation promoter and a catalyzer to the mixed liquid of a liquid type phenolic resin and a melamine resin the then hardening it through equal churning, drying and heating. CONSTITUTION:Phenolic and melamine liquid resins are used for materials. And grindstone particles, a pore formation promoter as well as a catalyzer are added to the material which is hardened by equal churning, drying and heating. A synthetic grindstone produced by the above method is an excellent semi-elastic grindstone and various grindstones are obtainable by changing properly mixing rate, between both resins, void ratio and heat treatment conditions. Furthermore, this synthetic grindstone has a good autogenous formation due to its proper fragility and capability to discharge smoothly grinding scraps and dropped grindstone particles from the surface of metarials to be abraded through voids and further the production of high count grindstones is possible, whereby the high precision abrasion of comparatively hard metals is feasible.

Description

[Detailed description of the invention] (Applications with industry) The present invention provides a solid grindstone using synthetic resin as a binding material.

This article relates to a so-called remade grindstone that is suitable for relatively precision polishing, and a method for manufacturing the same.

(Conventional technology) Conventionally, solid grindstones for polishing have generally been made by holding and fixing fine particles of abrasive grains using some kind of binding material. Examples include a resin-based grindstone using a phenolic thermosetting resin, a PVA-based elastic grindstone using a polyvinyl acetal resin, etc., and the amount III used for each differs depending on its characteristics. 、Shi/noid type grindstone has resin type: n、manufacturing condition、
There are a wide range of applications for TI7, from grinding to final polishing, which vary depending on the particle size of the abrasive grains used. and polyvinyl acetal-based elastic grinding wheels.

It was called a semi-elastic whetstone and was highly praised as a high-performance whetstone with excellent grinding and polishing power. The thermosetting resin used as the binding material for resinoid grinding wheels is generally phenolic resin.

The manufacturing method is usually to mix abrasive grain powder and phenolic resin powder, knead with liquid phenolic resin powder to make a viscous paste, put this into a predetermined mold, press mold, heat press solidify, and then The method used was to perform curing to harden the material.

(Problems to be Solved by the Present Invention) Resinoid grindstones manufactured by the method described above have a relatively low porosity, which is an important element of a grindstone, and a high bulk specific gravity, making them heavy and difficult to use. Since a method of mechanically mixing powdered resin and abrasive grains is used, it is extremely difficult to uniformly disperse fine abrasive grains, and the manufacturing limit is at most 10%.
The abrasive grain size is about 0.004 (average grain size of approximately leg ■), and it has the disadvantage that it is very difficult to obtain one with a higher grit. Moreover, the low porosity is extremely disadvantageous in terms of escape of polishing debris and dissipation of polishing heat. There were some disadvantages. It is also difficult to apply precision polishing to surfaces plated with relatively hard metals such as chromium, nickel, etc., and polishing that requires high precision remains inefficient and costly. It relied on the sipping method using loose abrasive grains and the puff finishing method, which had many environmental problems.

In view of the above-mentioned drawbacks and current problems of conventional resinoid grinding wheels, the present inventors conducted intensive research and completed the present invention. Metal surfaces with excellent smoothness and high surface precision, especially relatively hard metal surfaces, can be economically advantageously and
33 to be obtained without environmental pollution problems. Another purpose is to provide a resinoid grindstone with a relatively high porosity and excellent polishing performance.

(Means for Solving the Problems) The above object is to provide a structure having a three-dimensional separate structure with a porosity of 30 to 80% by volume, the structure consisting of a phenolic resin (P) and a melamine resin. This is achieved by a synthetic abrasive stone characterized by consisting of a matrix whose main component is a two-component thermosetting resin cured product of (M) and abrasive grains that are densely embedded and fixed in the matrix. Ru.

The method of the present invention for obtaining such a synthetic grindstone is based on liquid phenolic fruit tree 11ti (P) and liquid melamine resin (M
) and abrasive grains to the mixture mainly consisting of.

``[It is characterized in that the intermediate is made by reacting and solidifying a slurry-like stock solution in which a flower-forming agent and a catalyst are added and uniformly stirred, and after drying to remove moisture and/or solvent, the intermediate is cured by heat treatment. It is something.

In other words, 1. While the bonding material of conventional resinoid grinding wheels is mostly composed of hardened phenolic resin, the present invention uses melamine resin to suppress the toughness and give brittleness. The main aim is to further increase the porosity and improve the sustainability of polishing performance, and in particular to give resinoid-based grindstones physical properties suitable for precision polishing. .

The present inventors have found that performance suitable for precision polishing, in other words, excellent performance for self-sharpening of the cutting edge, is achieved by applying a two-component hardened product of phenolic resin and melamine resin as the main components of the grinding wheel matrix. This suppresses the toughness (stickiness) of the cured phenolic resin as a binder and maintains appropriate brittleness.
It was discovered that this can be obtained by adding . In other words, the hardened phenolic resin has relatively high toughness, so conventional resinoid grinding wheels.

Although it is not possible to fully demonstrate its performance unless it is crimped with high pressure and polished, it is possible to fully demonstrate its performance with a low weight by using a hardened melamine resin in the matrix. I found it.

The composition ratio of phenolic resin (P) and melamine resin (M) is preferably set to P/M 1/2 to 3/l at 1 mμ base; if it exceeds this, melamine resin is used in combination. The effect is weak and almost the same as that of conventional resinoid-based synthetic whetstones.

If it is less than this, it will become brittle and it will be difficult to demonstrate its performance as a resinoid-based grinding wheel, so it is undesirable in any case.Furthermore, the porosity of the matrix needs to be set within the range of 30 to 30% by volume. be.

In other words, if it is less than 30% by volume, polishing debris and falling abrasive grains)
It lacks accelerating ability and tends to cause clogging phenomena.

Moreover, if the volume exceeds 90%, it lacks structural strength and is difficult to perform as a grindstone.A particularly preferable range is 40 to 80% by volume.

Next, the method for manufacturing the synthetic grindstone will be described in detail.

The conventional manufacturing method for resinoid grinding wheels is to mix abrasive grains and hardened phenolic novolac resin powder at a predetermined ratio, add liquid phenolic resin to this, and knead to prepare a paste-like stock solution. A common method has been to mold the paste-like stock solution in a predetermined mold and then harden it using a hot press.

With this method, high porosity is undesirable;
The limit is 30% by volume at most, and since the method involves mixing powdered raw materials, it is difficult to mix fine particles uniformly, and unevenly distributed lumps, so-called "mamako", and uneven layers are likely to form. , the limit of abrasive grain size is too much,
I couldn't get anything better than that.

The inventors did not seek powder as the raw material for the resin.

The raw material is an aqueous solution, solution, or emulsion of phenol-based and melamine-based liquid resins, that is, resin stock solutions or resins, or their precursors such as polymers, oligomers, and low polymers, and abrasive particles -F are added to the liquid. It was discovered that abrasive grains of any particle size can be dispersed extremely easily and uniformly in the stock solution by adding and stirring uniformly.

In addition, by using each liquid of phenolic resin and melamine resin, mutual mixing of resin liquids is possible.
For example, it is possible to avoid the disadvantage that only one resin is unevenly distributed in the form of lumps, stripes, or layers. More preferably, the above-mentioned disadvantages can be completely avoided by using the two resin liquids with substantially the same viscosity □.

Next, in the method of the present invention, a pore-forming agent was also used.
This is an important feature. That is, since conventional resinoid grindstones are manufactured by the method described above, the voids are formed by the gaps between particles that occur when resin powder and abrasive powder are mixed, and the mixing method The porosity varied depending on the temperature and was unstable at the same time. In addition, in the method of the present invention, the porosity and pore diameter can be controlled by using a pore-forming agent, so that the desired structure can be obtained extremely stably.

In other words, the liquid resin liquid undergoes a condensation cross-linking reaction at a relatively low temperature in the presence of a catalyst to solidify into a gel, and as it solidifies, it separates from the medium water or solvent. However, in order to prevent the volume shrinkage during the solidification reaction process and form stable pores, a pore forming agent is used in the uninvented method.

As the pore-forming agent, one that is easily dispersible in water is used, and specific examples thereof include starch, C powder modified product, cellulose modified product, surfactant, water-soluble polymeric substance, and the like. Pore-generating agents that are dispersed in water, such as starches and modified cellulose, form pores where they existed, so the pore size can be controlled appropriately by varying the consistency of the pore-generating agent. obtain. The amount of these pore forming agents used is 0.5 to 5.0'/
% is preferable; if it is too small, the effect will be weak, and if it is too large, it will be difficult to knead and it will be impossible to form a uniform structure. Furthermore, water-soluble polymers such as surfactants, polyethylene glycol, polypropylene glycol, or their derivatives are more suitable for uniformly forming fine pores than the starches, and in particular, the average pore diameter is 0.1 to le#L
It has the property of stably forming a substance of about s.

The liquid phenolic resin used in the present invention is a resin stock solution, an aqueous emulsion of a precursor of monomers, oligomers, polymers, etc., a solution of NI etc. dissolved in an appropriate solvent, and a catalyst such as an acid. Particularly suitable are aqueous solutions of initial products of resol resins that can be crosslinked in the presence of a basic catalyst, that is, phenols, and aldehydes, which are produced by reacting them with aldehydes in the presence of a basic catalyst.

Liquid melamine resin is an aqueous emulsion of a resin or a precursor made of its monomers, oligomers, polymers, etc., or a solution dissolved in an appropriate solvent, which undergoes intermolecular condensation or crosslinking in the presence of a catalyst such as an acid. that can be hardened,
In particular, it is suitable to use an aqueous solution thereof to carry out the method of the present invention.

ξ The phenolic resins and melamine resins mentioned here are
In the presence of a catalyst, condensation and solidification reactions occur even at relatively low temperatures (30 to 100°C), resulting in a solid form, but at this stage it is soft and not hard enough, and its performance as a grindstone is poor. It is an intermediate, so to speak.

After drying this intermediate to remove moisture or solvent, heat treatment curing is performed to accelerate the crosslinking reaction caused by the aforementioned condensation and harden it, thereby making it possible to obtain the physical properties required for the desired grindstone.

The temperature suitable for curing is 100 to 200° C. for 1 hour for about 3 to 50 hours.

The catalyst used here refers to acids, specifically 1M acid, sulfuric acid, mineral acids such as salted tuna, vinegar, oxalic acid,
Butyric acid, maleic acid, adipic acid.

Organic acids such as lactic acid, benzenesulfonic acid, and paratoluenesulfonic acid, or those that are acidic in aqueous solution, such as those made of strong acid and weak base, and hydrochlorides of organic amines, which generate acids when heated. Examples include things to do.

In the method of the present invention, as mentioned above, solidification proceeds at a relatively low temperature in the front step, and heat curing proceeds at a slightly high temperature in the subsequent step. It is preferable to use a mild catalyst, such as a metal salt made of a strong acid and a weak base, which can keep the chemical reaction to a low level, in order to proceed with the homogeneous reaction.

In order to improve the dispersion of abrasive grains in the stock solution and increase the abrasive retention power of Matrix 7, further enhancing its performance as a whetstone,
It is also effective to add small amounts of polyvinyl alcohol. Polyvinyl alcohol here refers to polyvinyl alcohol with an average degree of polymerization of 300 to 2000.1 degrees and its derivatives. In the method of the present invention, the polyvinyl alcohol reacts with aldehydes generated in the condensation reaction of melamine resin or phenol resin, This is polyvinyl acetal resin.

By adding polyvinyl alcohol, it is preferable to add the amount to an extent that does not change the performance of the grindstone of the present invention, specifically, about 0.1 to 5% by weight based on the total weight.
In particular, it improves the abrasive retention and uniform dispersibility of Takatake's abrasives (those using fine abrasive grains), and specifically, it is suitable to apply to abrasives of No. 2000 or higher.

The synthetic whetstone of the present invention is manufactured by one or more of the following methods, and has extremely excellent performance as a semi-elastic whetstone, and its performance is also achieved by mixing 1.1. By appropriately changing the porosity and heat treatment (curing) conditions, it is possible to create a wide variety of products.

In addition, the type of abrasive grains is not particularly limited; diamond/de,
Boron nitride, silicon carbide, fused alumina.

Although fine powders of chromium oxide, cerium oxide, etc. can be used, those made of at least one abrasive material selected from the group consisting of silicon carbide, fused alumina, chromium sulfide, and cerium oxide are particularly preferred.

(Function) Generally, the polishing action of a solid grindstone can be explained as follows.

The abrasive grains on the surface of the whetstone in contact with the object to be polished play the role of a cutting edge by sliding, rotating, or being rubbed relative to each other.
As it grinds the surface of the object to be polished, it falls off due to the frictional force. At the same time, new abrasive grains appear on the surface and have the same effect,
The so-called self-growth process is repeated, and the overall grinding and polishing operations are performed in parallel. In other words, the whetstone polishes the other object while abrading itself, and the matrix, which is the binding material, holds the abrasive grains appropriately, and the 11Q
In other words, the matrix must have hardness, toughness, and brittleness depending on the material of the material to be polished. What is also important is that grinding debris and fallen abrasive grains caused by the polishing action are smoothly discharged from the polishing surface. If this effect is insufficient, the abrasive surface will become clogged, the polishing performance will be extremely degraded over time, and undesirable results such as a single polishing spot will occur.

The synthetic whetstone of the present invention is extremely suitable for the above-mentioned polishing action, has appropriate brittleness, has excellent self-growth action, and has the ability to trap polishing debris and de-abrasive grains through its voids. be. In addition, since it is possible to manufacture high-grip products that are difficult to produce with conventional resinoid grindstones, this has conventionally been possible only with a lapping polishing method or a puff polishing method using M superabrasive grains. Precision polishing of relatively hard metals (
Final polishing) has also become possible with the synthetic grindstone of the present invention.

Hereinafter, the present invention will be specifically explained in detail by giving examples.
66% aqueous solution 2501 of R-981A was made into a 60% aqueous solution 150 of Sumitomo Chemical -3 as a water-soluble melamine resin.
g 1 l mixed with each other, zinc nitrate and chloride as catalyst! ■Add the amount of iron and add 40g of cornstarch to 25g.
Silicon carbide 15 as a liquid dispersed in water of 01 and abrasive grains
1 kg of No. 00 fine powder was added, stirred uniformly, cast into a predetermined mold, and reacted and solidified in a water bath at 50° C. for 50 hours to obtain an intermediate. After drying this.

Curing was performed at 145° C. for 20 hours to obtain a synthetic grindstone. The grindstone obtained here has a phenol content of 15.2
%, melamine content 8.3%, P/) I-1,871, abrasive grain rate 7G, 5vt%, porosity 43mm 01%, hardness measured with Rockwell hardness meter Superficial l5-Y scale is 55. there were.

When this was molded into a disk shape and subjected to grinding of a chrome-plated cylinder, good surface accuracy was obtained, and phenomena such as clogging did not occur.

(Example 2) The phenolic resin aqueous solution 2001 used in Example 1 and the melamine resin aqueous solution 1201 were mixed.

□ Add a small amount of organic amine hydrochloride as a catalyst,
A liquid in which 40 g of corn starch was dispersed in 2501 water, a 10% polyvinyl alcohol aqueous solution 1001, and white alumina (fused alumina) No. 4000 abrasive fine powder 9
The slurry II-like stock solution obtained by adding 00 g of each and stirring uniformly was cast into a predetermined mold, and reacted and solidified in a water bath at 40° C. for 40 hours to obtain an intermediate. After drying this, curing was performed at 170° C. for 24 hours to obtain the desired synthetic grindstone.

This whetstone has a phenol content of 10.1vt$, a melamine content of 5.6wt$, and a P/M = 1.8/1. Abrasive grain rate 84
．． 4wt$, void $57 v o I Z *Rockwell hardness tester.

The hardness measured with the Super Fishiyashi 15Y scale is -
28, with an average pore diameter of 2 OIL. When this synthetic whetstone was formed into a ring shape and used for surface polishing of a nickel-plated metal plate, the degree of surface area R4 = 0.02 #
A finished surface of L■ was obtained.

(Comparative example) Jib Example 1 The phenolic resin aqueous solution and melamine resin aqueous solution used in Te were used as resin raw materials, zinc nitrate and ferrous chloride were used as catalysts, and silicon carbide 1500 was used as abrasive grains.
A synthetic whetstone having the following composition was obtained according to the method shown in Example 1 using Co7 starch as a pore-forming agent.

Abrasive grain rate 75. OwtX abrasive rate? 2.5 wtX porosity 43.8vo1% abrasive grain rate 53.9 wtX porosity 23.0mm01 melamine% lZ, awt abrasive grain rate 65.1 wtX porosity 30.11o1% These are Example 1 Similarly, when a chromium-plated cylinder was subjected to grinding, the following results were obtained.

(a) It is a little too hard and does not fit the chrome plated surface.

I couldn't polish it.

(a) It was too brittle, causing severe wear on the grindstone, and could not withstand high-speed rotation.

(c) The clogging phenomenon was severe and frequent dressing operations were required.

(d) The grinding wheel was severely worn and could not keep up with the accuracy of the 2nd machine for polishing.

(Effect of the invention) This was considered to be a drawback of conventional resinoid grindstones. The clogging phenomenon caused by low porosity has been significantly reduced with the advent of the synthetic grindstone of the present invention, and it has also become possible to apply resinoid grindstones in the field of flat precision polishing, which has been relatively difficult until now. Also noteworthy is the fact that it has become possible to obtain products that are lightweight and easy to handle.

Furthermore, the method of the present invention makes it possible to manufacture high-count products, which was previously difficult. *A lapping method using abrasive grains,
In addition, it has become possible to obtain products that can cover the field of puff finishing methods.

Furthermore, in the method of the present invention, there is no quantitative difficulty in producing the stock solution, and the method of casting into a mold is adopted, so it is possible to produce even quite large products, including @-shaped and plate-shaped zero discs. It can be formed into a cylindrical shape, a block shape, etc., and can be molded into any complicated shape, especially if it is processed at the intermediate stage. In other words, it becomes possible to diversify in terms of performance and shape, and the application of conventional resinoid grindstones [which can be far beyond 1 m]3.

In this way, the effects of the synthetic whetstone of the present invention are extremely large, and it has been difficult to use conventional synthetic whetstones for hard metals, for example, plating with chromium, nickel, etc., which relied on lapping and puff finishing methods using AM abrasive grains. Precise polishing of polished surfaces has become possible with the use of high-precision products. As a result, the consumption of expensive abrasive grains is significantly reduced, which brings about economic effects.It also reduces the problem of contamination of workers and the environment, and also reduces the burden of processing high-concentration waste liquid.
The impact is extremely large. In addition, even with conventional grits, the porosity is higher and the sustainability of polishing performance is improved, specifically, the polishing work can be continued without dressing (surface renewal) work, and the specific gravity is lower. Replacement work due to decline, i! ! ! It also significantly contributes to improving work efficiency, such as by significantly reducing the labor involved in transport work.

Claims (1)

[Scope of Claims] 1) A structure having a three-dimensional network structure with a porosity of 30 to 90% by volume, wherein the structure is composed of two components of a phenolic resin (P) and a melamine resin (M). A synthetic whetstone characterized by comprising a matrix whose main component is a cured thermosetting resin, and abrasive grains that are densely embedded and fixed in the matrix. 2) The synthetic whetstone according to claim 1, wherein the phenolic resin (P) and the melamine resin (M) have a composition ratio of 1/2 to 3/1 on a weight basis. 3) The synthetic whetstone according to claim 1 or 2, wherein the abrasive grains are made of at least one abrasive material selected from the group consisting of silicon carbide, fused alumina, cerium oxide, and chromium oxide. 4) An intermediate obtained by reacting and solidifying a slurry-like stock solution obtained by adding abrasive grains, a pore-forming agent, and a catalyst to a mixed liquid mainly consisting of a liquid phenolic resin (P) and a liquid melamine-based resin (M) and stirring uniformly, A method for producing a synthetic whetstone, which comprises drying to remove moisture and/or solvent, and then subjecting it to heat treatment to harden it. 5) Liquid phenolic resin (P) and liquid melamine resin (M
) and has a composition ratio of P/M=1/2 to 3/1 on a solid content basis. 6) The method for producing a synthetic grindstone according to claim 4 or 5, wherein the liquid phenolic resin is an aqueous solution of a water-soluble resol resin. 7) The method for manufacturing a synthetic grindstone according to any one of claims 4 to 6, wherein the liquid melamine resin is an aqueous solution of a water-soluble melamine resin. 8) The method for producing a synthetic grindstone according to any one of claims 4 to 7, wherein the pore-forming agent is starch or a modified product thereof. 9) The method for producing a synthetic grindstone according to any one of claims 4 to 8, wherein the catalyst is a salt consisting of a strong acid and a weak base. 10) The method for producing a synthetic grindstone according to any one of claims 4 to 9, wherein 0.1 to 5% by weight of polyvinyl alcohol is added to the slurry stock solution based on the total amount.