JPH0673820B2 - Abrasive material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an abrasive used for final polishing of magnetic heads and magnetic disks, precision final polishing of dies, and the like, and abrasive particles in a polishing layer. The present invention provides an abrasive that does not fall off and exhibits an excellent polishing action.

[Conventional technology]

The surfaces of precision electronic parts and magnetic heads of precision machine parts are
It is often necessary to finish on a micron or sub-micron order uneven surface, and inorganic fine powder with high hardness is dispersed in a resin solution on a polishing tape base made of film or synthetic paper. A polishing tape (for example, Japanese Patent Publication No. 53-44714) having a polishing layer formed by a dispersion resin solution of the inorganic fine powder is used.

However, the polishing layer in the conventional polishing tape is based on a coating liquid for forming a polishing layer in which abrasive particles made of inorganic fine powder are dispersed in a solution of a thermoplastic resin, a thermosetting resin, or a reactive resin. It is generally formed by applying it on a material and then performing a post-treatment depending on the type of resin in the coating liquid.

[Problems to be solved by the invention]

By the way, in the conventional polishing tape, in the case of a coating liquid for forming a polishing layer using a thermoplastic resin, the abrasive particles (inorganic fine powder) and the thermoplastic resin as a binder component in the obtained polishing layer are The bonding force between them is weak, and the abrasive particles easily fall off. Therefore, in the case of using a coating liquid for forming a polishing layer using a large amount of a binder component with respect to the abrasive particles, the amount of the abrasive particles exposed on the surface of the obtained polishing layer becomes small. However, it has a drawback that a polishing tape having a sufficient polishing ability cannot be obtained.

Further, in the case of a coating liquid for forming a polishing layer using a thermosetting resin or a reactive resin, the volume contraction of the coating liquid occurs at the time of thermosetting for forming a polishing layer, and the above-mentioned thermoplastic resin is used. It is possible to form a polishing layer with many abrasive particle surfaces exposed on the surface of the polishing layer, but this is not sufficient, and the storage stability of the coating liquid for forming the polishing layer is stable. Since it is difficult to maintain uniform physical properties of the coating liquid because it has poor properties, it is difficult to obtain a uniform polishing layer, and when forming the polishing layer, it takes a long time for curing and heat treatment after coating the coating liquid. Therefore, there are drawbacks such as poor production efficiency.

On the other hand, the present invention has a property of excellent polishing action,
There is no loss of abrasive particles in the polishing layer, the storage stability of the coating liquid for forming the polishing layer is good, a uniform polishing layer can be easily obtained, and after the coating during the formation of the polishing layer. It is possible to provide an abrasive having characteristics such as easy processing.

[Means for Solving Problems] In the polishing material of the present invention, the polishing layer on the base material for the polishing material is prepared by using a coating solution for forming a polishing layer containing the following urethane (meth) acrylate compound as a binder component. In the coating layer,
Moreover, the coating layer is subjected to radiation irradiation treatment.

Urethane (meth) acrylate compound (i) Number average molecular weight ...... 1000 to 20000 (ii) Number average molecular weight from the side chain bonding point to the terminal is 500
More than one side chain: 1 or more in one molecule (iii) Number of (meth) acryloyl groups: 3 in one molecule
Or more (iv) Position of (meth) acryloyl group .... End of side chain having number average molecular weight of 500 or more from both ends of main chain and end points of side chains to ends. A polishing layer comprising a base material and a polishing layer formed on the base material as essential constituents, and the polishing layer contains the specific urethane (meth) acrylate compound as a binder component. A coating layer formed by a coating liquid for forming is subjected to radiation irradiation treatment, and a base material for an abrasive material on which a polishing layer is formed is polyethylene terephthalate,
Various plastics such as oriented polypropylene, polycarbonate, diacetate acetate, triacetate acetate,
It is suitable to provide a metal vapor deposition layer of Al, Cu, Sn, Zn or the like on each of the various plastics, and for example, films, tapes, sheets, disks, cards, drums and the like are used.

The coating liquid for forming the polishing layer applied on the base material for the polishing material contains, as described above, a urethane (meth) acrylate compound having a specific structure as a binder component, for example, acetone, Ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;
Esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol monoethyl ether acetate; ethers such as ethyl ether, glycol dimethyl ether, glycol monoethyl ether, dioxane, tetrahydrofuran; aromatics such as benzene, toluene, xylene Hydrocarbon: A coating liquid using an organic solvent such as chlorinated hydrocarbon such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, dichlorobenzene can be used.

The abrasive particles, which are the essential components in the coating liquid for forming the polishing layer, are, for example, aluminum oxide, silicon carbide, silicon nitride, zirconium oxide, chromium oxide, iron oxide, diamond, nitrogen boro, emery. , Fine powder such as silicone carbide is used, but if the particle size is less than 0.3μ, the polishing efficiency of the resulting abrasive is poor, and if the particle size exceeds 40μ, precise finishing can be performed. Since no abrasive material can be obtained, abrasive particles having a particle size of 0.3 to 40 μm are usually used.

If necessary, the coating liquid for forming the polishing layer may contain an additive such as a dispersant and an antistatic agent, and further, a vinyl-based monomer polymerizable by irradiation of radiation, that is, , Compounds having one or more carbon-carbon unsaturated bonds in one molecule, such as acrylic acid esters, acrylamides, methacrylamides, methacrylic acid esters, allyl compounds, vinyl ethers, vinyl esters, vinyl heterocyclic rings A compound, N-vinyl compound, styrene, acrylic acid, methacrylic acid, croton brew, itacone brew, olefin, etc. may be added and contained. The preferable vinyl-based monomer that can be polymerized by irradiation is a compound containing two or more acryloyl groups or methacryloyl groups, and specifically, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate. Acrylates of polyethylene glycol, such as
Trimethylolpropane triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, Tris (β-acryloyloxyethyl) isocyanurate, bis (β-acryloyloxyethyl) isocyanurate, or polyisocyanate (for example, 2,4-tolylene diisocyanate, 1,3-xylylene diisocyanate, hexamethylene diisocyanate, etc.) ) And a hydroxy acrylate compound (β-hydroxyethyl acrylate DOO, reacting the compound with β hydroxypropyl acrylate), or other 2
Acrylates and methacrylates such as esters of functional or higher polyols with acrylic acid or methacrylic acid can be added in an amount of 50% by weight or less of the urethane (meth) acrylate compound as a binder component.

Incidentally, the coating liquid for forming the polishing layer is usually 100 parts by weight of the urethane (meth) acrylate compound and the polymerizable vinyl-based monomer optionally contained, and 100 parts by weight of the abrasive particles. It is contained in an amount of about 400 parts by weight, and is applied to a base material for an abrasive in a thickness of about 10 to 50 μm.

Further, the irradiation of the radiation applied to the coating layer of the coating liquid for forming the polishing layer is carried out by electron beam, γ ray, β ray, etc.
For example, in the case of electron beam irradiation, the energy transmission amount is insufficient at an acceleration voltage of 100 KV or less, and if it exceeds 1000 KV, the energy efficiency used for polymerization is reduced and it is not economical, and
If the absorbed dose is less than 1 Mrad, the curing reaction is insufficient, so a strong polishing layer cannot be obtained, and if it exceeds 20 Mrad, the energy efficiency used for curing decreases, and the base material for the abrasive material heats up and deforms. Therefore, the acceleration voltage is 100 to 1000 KV, preferably 150 to 300 KV, and the absorbed dose is 1 to 20 Mrad, preferably 3
It is desirable to perform electron beam irradiation under the condition of ~ 15 Mrad. The electron beam accelerator may use a scanning method, a double scanning method, a curtain beam method, a broad beam curtain method, or the like.

Further, before or after the irradiation treatment of the radiation applied to the coating layer by the coating liquid for forming the polishing layer, the coating layer may be calendered.

The above-mentioned urethane (meth) acrylate compound used as a binder component in the polishing layer of the polishing material of the present invention has a number average molecular weight of 1000 to 20000, preferably 2000 to 15000.
Something is used. In addition, the urethane (meta)
When the acrylate is a urethane (meth) acrylate having one or more -COOH group in the molecule, the wetting of the abrasive particles and the binder component and the wetting of the binder component and the substrate surface are better. Further, it is an abrasive having a polishing layer having various physical properties.

In the abrasive material of the present invention having the configuration as described above,
Since the urethane (meth) acrylate compound, which is the binder component of the polishing layer in the polishing material, is characteristic, the urethane (meth) that is the binder component will be described below.
The acrylate compound will be described.

Specific examples of the urethane (meth) acrylate compound as the binder component in the polishing layer of the polishing material of the present invention include: Etc. are displayed.

In the urethane (meth) acrylate compound represented by the above general formula, M ^{1 to} M ⁶ other than hydrogen may be the same or different, and other than hydrogen M ^{1 to} M ⁶ have a number average molecular weight, because if the molecular weight is 500 terminals, curing defects may occur due to irradiation with radiation, or the mechanical strength of the resulting cured film may decrease. Is 500 or more, preferably 7
It is said to be 00 or more. Also, the part displayed with "X" is It is preferable that the urethane (meth) acrylate compound has one or more groups represented by the following, from the viewpoint of self-dispersibility of the urethane (meth) acrylate compound.

A typical method for obtaining the urethane (meth) acrylate compound used in the present invention will be described below.

First, a first step of reacting a diisocyanate compound [A] with a polyester compound [B], which is a polyester prepolymer having hydroxyl groups at both ends, to obtain a diisocyanate prepolymer having isocyanate groups at both ends. A radically polymerizable compound having a hydroxyl group at a terminal and a diisocyanate prepolymer obtained in the first step, that is, a radically polymerizable compound [D] comprising a (meth) acrylic acid ester having a hydroxyl group at a terminal
A second step of obtaining a compound in which both are bonded by a urethane bond, and a compound obtained in the second step. This is a method comprising a third step of obtaining a target compound by reacting with a trivalent or higher hydroxy compound such as trimethylolpropane, pentaerythritol, dipentaerythritol. In the first step of the above-mentioned steps, a diisocyanate compound [A], a polyester compound [B] which is a polyester prepolymer having hydroxyl groups at both ends, and a carboxylic acid having two hydroxy groups in the molecule are used. By reacting with the compound [C] to obtain a diisocyanate prepolymer having isocyanate groups at both ends, a urethane (meth) acrylate compound as a target compound having a —COOH group in the molecule is obtained. It is what is done.

The diisocyanate compound [A] used in the first step of the typical method for obtaining the urethane (meth) acrylate compound is an aliphatic or aromatic polyvalent isocyanate compound having two isocyanate groups in one molecule. And, for example, tetramethylene diisocyanate, hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4-naphthenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 3-3-dimethyl -4,4'-Diphenylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, trimethylhexamethylene diisocyanate and the like are used alone or in a mixture of two or more kinds.

Similarly, the polyester compound [B], which is a polyester prepolymer having hydroxyl groups at both ends, is a ring-opening polyester compound derived from a condensation product of a polybasic acid and a polyhydric alcohol and a cyclic ester compound.
For example, saturated polybasic acids such as phthalic acid, isophthalic acid, terephthalic acid, adipic acid, succinic acid and sebacic acid, unsaturated polybasic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid, ethylene glycol, Trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 2,2-dimethyllopane-1,3-diol, 2,2-diethylpropane- 1,3-diol, cyclohexane-1,3-diol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, cyclohexane-1,3-dimethanol, 2,2-bis (4-hydroxyethoxy) -Cyclohexyl) propane, 2,2-bis (4-hydroxyeth) Xy-phenyl) propane, 2,2-bis (4-hydroxyethoxynitoxy-
Polyester compounds as esterification reaction products with polyhydric alcohols such as phenyl) propane, and polyester prepolymers obtained by ring-opening polymerization of ε-caprolactone, δ-valerolactone, lactone compounds of their respective derivatives, etc. The degree of polymerization is generally 1 to
About 30 are used. In particular, the formula Z ¹ −Y ¹ −Z ² (Z ¹ , Z
² is a poly capsule lactone Units - those that repeating unit of 1 to 10, Y ¹ in the caprolactone-based polyester prepolymer represented by the diol residues), Y ¹
As the diol compound represented by, for example, the same type of polyhydric alcohols as those exemplified above can be used, but preferably, It is preferable to use the caprolactone-based polyester prepolymer using a diol compound such as

Further, as the carboxylic acid compound [C] having two hydroxy groups in the molecule, which is used as desired, for example, (CH ₂ OH) ₂ C (CH ₃ ) COOH etc. are used.

The radical polymerizable compound [D] composed of a (meth) acrylic acid ester having a hydroxyl group at the terminal used in the second step is, for example, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate. , Hydroxypropyl methacrylate, hydroxybutyl methacrylate, 4-hydroxycyclohexyl acrylate, 5-hydroxycyclooctyl acrylate, 5
-Hydroxycyclooctyl acrylate, 2-hydroxy-3-phenyloxypropyl acrylate and other radically polymerizable compounds having one polymerizable unsaturated group, the formula There are radically polymerizable compounds having two polymerizable unsaturated groups represented by. In the example of the method for obtaining the urethane (meth) acrylate compound used in the present invention, the reaction between the hydroxyl group and the isocyanate group is a known method, that is, both reaction components of the compound having a hydroxyl group and the compound having an isocyanate group are prepared. A method of mixing and heating to 40 to 100 ° C can be used. As the solvent at the time of mixing, a monomer active to ionizing radiation can be used, but it is better to react in a solvent that is not reactive with an isocyanate group, or even if it is reacted in the absence of solvent. good. In addition, triethylamine, piperazine, triethanolamine, dibutyltin dilaurate, stena octoate, stanas laurate, dioctyltin dilaurate and the like can be used in this reaction system for the purpose of promoting the reaction.

Further, a reaction system of a hydroxyl group and an isocyanate group between the radically polymerizable compound [D] composed of a (meth) acrylic acid ester having a hydroxyl group at the terminal and the diisocyanate prepolymer obtained in the first step of the reaction, and a third system In the reaction system and the like in the step, the radical polymerizable compound [D]
A polymerization inhibitor for protecting the acrylic acid ester group therein, for example, hydroquinone, hydroquinone monomethyl ether, benzoquinone, 2,6-di-t-butyl-p-
It is advisable to add cresol or the like at about 10 to 1000 ppm.

〔Example〕

Hereinafter, a specific configuration of the abrasive of the present invention will be described with reference to production examples.

Example Synthesis of urethane (meth) acrylate compound In a four-necked flask having a capacity of 5 l equipped with a stirrer, a thermometer, a condenser and a dropping funnel, 783 g of toluene diisocyanate, 1.0 g of dibutyltin dilaurate, 67 g of dimethylol propionic acid and 250 g of MEK were added. After charging, the mixture was stirred at room temperature (23 ° C) for 30 minutes.

Then, 1325 g of a polyester prepolymer (manufactured by Daicel Corp .: Praxel 205: molecular weight 530) in the reaction solution
And a polyester solution of MEK610g are dropped, and after the dropping is completed, 4
After stirring for 2 hours in a heated state of 0 to 50 ° C, benzoquinone
195 g of hydroxyethyl methacrylate containing 0.2 g was added dropwise, and the mixture was stirred for 1 hour under heating at 50-60 ° C.

Further, a solution prepared by dissolving 67 g of trimethylolpropane in 200 g of MEK was dropped into the reaction solution in a heated state of 50 to 60 ° C., and stirred for 3 hours while maintaining the heated state, and 0.4 g of hydroquinone was added. A clear solution of the urethane methacrylate compound was obtained.

In addition, the urethane methacrylate compound in the urethane methacrylate compound solution has a number average molecular weight of 3100 by GPC, the number of methacryloyl groups contained in one molecule is three, and the methacryloyl group is at both ends of the main chain and the side. The number average molecular weight from the point of attachment of the chain to the end is at the end of the side chain of about 1000, The main urethane methacrylate compound represented by
M ¹ , M ² and M ³ are displayed as M ¹ = M ² ...... (TDI-Plaxel 205) _2- TDI-HEMA M ³ ...... TDI-Dimethylolpropionic acid-TDI-Plaxel 205-TDI-HEMA It is something.

Preparation of coating liquid for forming polishing layer 1 kg of aluminum oxide fine powder having an average particle diameter of 2 μm was mixed with 360 g of the methyl ethyl ketone solution of the urethane methacrylate compound and 300 g of methyl ethyl ketone, and after stirring,
The obtained aluminum oxide differential powder dispersion (viscosity 500 cps)
Was filtered through a wire mesh filter having a mesh size of 5 μm to obtain a coating liquid for forming a polishing layer.

Production of abrasive material The surface of the substrate for the abrasive material consisting of a film made of polyethylene terephthalate with a thickness of 75μ, after applying the coating liquid for forming the polishing layer with a doctor blade, 100 ℃, dried for 1 minute, thickness A coating layer having a thickness of 10 μm was formed.

Then, on the coating layer surface, accelerating voltage 175KV, beam current 5m
After irradiation with electrons having an absorbed dose of 5 Mrad at A, slitting was performed to a width of 1 inch to obtain an abrasive having an abrasive layer as an example of the present invention.

Characteristics of Abrasive Material The obtained abrasive material does not fall off of fine aluminum oxide powder as abrasive particles even if it is rubbed with a polishing layer in the abrasive material with a nail for several tens of times, and the final polishing of a magnetic disk is performed by the above-mentioned polishing. When it was carried out on the material, no trouble such as generation of scratches due to grain shedding occurred at all, and it had excellent properties in grinding performance.

[Operation and effect of the invention]

The polishing layer in the polishing material of the present invention is one in which the polishing agent particles are bound with a binder component that is completely cured by irradiation with radiation, and the polishing agent particles in the polishing layer do not fall off, and are excellent in polishing action. It has excellent performance.

Further, the coating liquid used for forming the polishing layer in the polishing material of the present invention has good storage stability of the coating liquid, and can easily maintain uniform physical properties of the coating liquid. Therefore, it is possible to easily obtain an abrasive having a uniform quality polishing layer.

Furthermore, in the abrasive of the present invention, when curing the coating layer of the coating liquid for forming the polishing layer, irradiation of radiation is utilized, and therefore when forming a cured polishing layer by thermosetting In comparison, since the post-treatment time after forming the coating layer is short, the production efficiency is excellent.

Claims (2)

[Claims] 1. An abrasive comprising a polishing layer formed on a base material, wherein the polishing layer has a side chain having a number average molecular weight of 500 or more from a bonding point of the side chain to the end in one molecule. An abrasive comprising a coating layer containing a coating solution for forming a polishing layer containing one or more of the following urethane (meth) acrylate compounds as a bander component, which has been subjected to radiation irradiation treatment. 2. A urethane (meth) acrylate compound,
The abrasive according to claim 1, which is a compound having one or more -COOH groups in one molecule.