JP3521560B2 - Abrasive - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abrasive material that can be used for surface polishing such as magnetic heads and glass fibers that require a high degree of surface finish.

[0002]

2. Description of the Related Art Since a magnetic head comes into contact with a recording medium at the time of recording or reproducing, the precision of the finished surface of the magnetic head greatly influences the sliding characteristic and the magnetic characteristic. In recent years, high-density recording of hard disks and floppy disks and high-density recording systems of magnetic tapes have begun to be used, and there is an increasing demand for finishing accuracy of the magnetic head surface in order to meet these requirements. Further, as the area of the glass fiber network is widened in order to cope with the highly information-oriented society, there is a demand for an abrasive material that accurately and easily polishes the glass fiber end surface. As a normal abrasive, particles of several μm such as diamond, aluminum oxide, and silicon carbide are used, and these are mixed with a synthetic resin as a binder and used. Polishing, which requires extremely high finishing accuracy, was impossible.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional technical problems, and provides an abrasive capable of smoothing the surface of a magnetic head or glass fiber and obtaining high finishing accuracy. With the goal.

[0004]

SUMMARY OF THE INVENTION The present invention comprises a base material, 1
7-95% by weight of a crosslinkable monomer having two or more groups having a polymerizable double bond in the molecule and a non-crosslinkable monomer
The polymerizable monomer containing, using a surfactant,
The average particle size obtained by emulsion polymerization is 0.01 to 2 μm.
An abrasive containing a layer containing m cross-linked polymer particles , and a polymerizable double bond in one molecule.
Crosslinkable monomers having two or more groups containing a compound
Polymerizable monomer containing 5% by weight and non-crosslinkable monomer
By emulsion polymerizing the polymer using a surfactant.
Crosslinked polymer having an average particle diameter of 0.01 to 2 μm
The present invention provides an abrasive in which particles are dispersed in a dispersion medium . Hereinafter, the present invention will be described in detail.

As the crosslinkable monomer, a non-conjugated polyvinyl compound typified by divinylbenzene or a polyvalent acrylate compound typified by trimethylenepropanetrimethacrylate, which has two or more copolymerizable double bonds described below, is used. Compounds may be mentioned, and these may be used alone or in combination of two or more. Specific examples of the crosslinkable monomer used in the present invention include polyethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,6-butylene glycol diacrylate, 1,
6-hexanelene glycol diacrylate, neopentyl glycol diacrylate, polypropylene diacrylate, 2,2'-bis (4-acryloxyproproxyphenyl) propane, 2,2'-bis (4-acryloxydiethoxyphenyl) Diacrylate compounds such as propane, trimethylol propane triacrylate, trimethylol ethane triacrylate, triacrylate compounds such as tetramethylol methane triacrylate, di trimethylol propane tetraacrylate, tetramethylol methane tetraacrylate, tetra acrylates such as pentaerythritol tetraacrylate Compound, ethylene glycol dimethacrylate,
Diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol methacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate,
Methacrylate compounds such as 1,6-hexane glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis (4-methacryloxydiethoxyphenyl) propane, trimethylolpropane tri Examples thereof include trimethacrylate compounds such as methacrylate and trimethylolethanetrimethacrylate, methylenebisacrylamide, and divinylbenzene. Of these, divinylbenzene, ethylene glycol dimethacrylate, or trimethylolpropane trimethacrylate is preferably used, and divinylbenzene is particularly preferable. The amount of the crosslinkable monomer used is 5% by weight or more of the polymerizable monomer,
Preferably 7 to 95% by weight, more preferably 10 to 9
It is 0% by weight. When the content of the crosslinkable monomer is less than 5% by weight of the polymerizable monomer, the hardness of the crosslinked polymer particles becomes insufficient and the polishing efficiency becomes poor.

In the present invention, in addition to the crosslinkable monomer, other copolymerizable monomers can be used (hereinafter simply referred to as "non-crosslinkable monomer"), and these can be used alone or in combination of two or more. To be done. Examples of the non-crosslinkable monomer include aromatic monovinyl compounds such as styrene, ethylvinylbenzene, α-methylstyrene, fluorostyrene and vinylpyrine, butyl acrylate, 2-ethylhexyl acrylate, β-methacryloyloxyethylhydrogenphthalate, N, N ′. -Acrylic ester monomers such as dimethylaminoethyl acrylate, 2-ethylhexyl methacrylate, methoxydiethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, methyl methacrylate,
Ethyl methacrylate, butyl methacrylate, N,
Examples thereof include methacrylic acid ester monomers such as N′-dimethylaminoethyl methacrylate and glycidyl methacrylate, vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, silicon-modified monomers and macromonomers. In addition, butadiene,
Conjugated double bond compounds such as isoprene and vinyl ester compounds such as vinyl acetate, 4-methyl-1-pentene,
Other α-olefin compounds may be mentioned. Among the non-crosslinking monomers, styrene, methylmethacrylate,
Acrylonitrile and the like are preferable. The amount of the non-crosslinkable monomer used is usually 95% by weight or less, preferably 10 to 90% by weight of the polymerizable monomer.

Next, a preferable method for producing the crosslinked polymer particles used in the present invention will be described. Examples of the method of adding the polymerizable monomer in the emulsion polymerization of the polymerizable monomer containing the crosslinkable monomer include a method of adding the whole amount at once and a method of adding a part or the whole amount continuously or intermittently.
A seed emulsion polymerization method can also be used. The polymerization initiator used in the emulsion polymerization of the polymerizable monomer containing the crosslinkable monomer is not particularly limited as long as it is used in ordinary emulsion polymerization, but is not limited to those such as potassium persulfate, sodium persulfate and ammonium persulfate. The sulfate-based initiator, azo-based initiator, hydrogen peroxide, organic peroxide and the like may be used alone or in combination with various reducing agents such as ascorbic acid.

Usual surfactants can be used as the above-mentioned emulsion polymerization.
Dodecylbenzene sulfonate, dodecyl sulfate, lauryl sulfate, dialkyl sulfosuccinate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethyne alkenyl propenyl phenyl ether sulfate,
Anionic surfactants such as a formalin condensate of naphthalene sulfonic acid can be exemplified. Here, examples of the salt include sodium and ammonium. Furthermore, it is also possible to use nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyethylene glycol monostearate, polyoxyethylene alkylpropenyl phenyl ether, sorbitan monostearate.

Further, it is possible to use a generally known reactive emulsifier such as sodium naphthalenesulfonate alone or in combination with the above-mentioned surfactant. These may be used alone or in combination. In the present invention, as a method for synthesizing the crosslinked polymer particles, it is possible to polymerize using polystyrene-based ultrafine particles as a seed. The average particle diameter of the crosslinked polymer particles used in the present invention is 0.01 to 2 μm, preferably 0.02 to 1.5 μm, and more preferably 0.03 to.
It is 0.08 μm. When the average particle diameter of the crosslinked polymer particles is larger than 2 μm, cutting scratches are formed on the surface of the magnetic head and the output is remarkably reduced, and when it is smaller than 0.01 μm, the desired cutting amount cannot be obtained, which is not preferable. The average particle size here is a particle size measured directly on 100 crosslinked polymer particles by a transmission electron micrograph (when the particles are not spherical, the major axis and the minor axis were measured and the average value was obtained). This is done by obtaining the average value of. In the present invention,
Further, if the surface of the crosslinked polymer particles is partially or entirely modified with a polymer obtained by polymerizing the non-crosslinkable monomer, the adhesion with the binder becomes good, which is preferable.

The abrasive of the present invention comprises an abrasive formed by forming a layer (polishing layer) composed of crosslinked polymer particles and a binder resin on a substrate, and a liquid formed by dispersing the crosslinked polymer particles in a dispersion medium. There is an abrasive. As the material that can be used as the base material in the above-mentioned abrasive, polyethylene terephthalate, polyimide, paper, non-woven fabric or the like is used.
As the binder resin, a conventionally known thermoplastic resin,
Thermosetting resin, electron beam curable resin, ultraviolet curable resin,
The visible light curable resins may be used alone or as a mixture of two or more thereof. The ratio of the binder resin used to 100 parts by weight of the crosslinked polymer particles is usually 0.1-10.
The amount is 00 parts by weight, preferably 1 to 100 parts by weight. The thickness of the polishing layer is usually 1 to 100 μm, preferably 10 to 30 μm. Water, alcohol, an organic solvent, or a mixture thereof can be used as the dispersion medium that can be used in the above abrasive. The amount of the crosslinked polymer particles dispersed in the dispersion medium is usually 0.1 to 90% by weight, preferably 1 to 10% by weight. In any of the above and above abrasives, an abrasive such as diamond, a dispersant, a lubricant, an antistatic agent, an antioxidant, a colorant and the like can be added in addition to the crosslinked polymer particles.

[0011]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto. In the following description, "part" means "part by weight" and "%" means "% by weight". Example 1 Divinylbenzene (manufactured by Sankyo Kasei, purity 55%, residual 4
Charge 0% ethyl vinyl benzene, the remaining 5% diethylbenzene) 18 parts, styrene 77 parts, acrylic acid 5 parts, sodium dodecylbenzene sulfonate 15 parts, ion-exchanged water 900 parts and sodium persulfate 1 part to the reaction vessel. Polymerization was carried out at 80 ° C. for 1 hour with stirring. The average particle size of the obtained polymer fine particles for abrasives was measured and found to be 0.
It was 03 μm. The obtained polymer fine particles were used to prepare a polishing layer coating liquid with the following composition. Polymer fine particles 90 parts by weight Diamond (average particle size 0.9 μm) 10 parts by weight Methacrylate-styrene copolymer 5 parts by weight Toluene 200 parts by weight The above components are sufficiently mixed and stirred with a tabletop sand mill (made by Kansai Paint Co., Ltd.). A coating solution for polishing layer was prepared. The polishing layer coating liquid thus obtained was coated on polyethylene terephthalate to a thickness of 1 μm to obtain an abrasive. An 8 mm VTR head was polished and finished for about 30 seconds using this abrasive, and Table 1 shows the evaluation results of the polished surface state of the head. (1) Observation of Polished Surface State The state of the polished surface was confirmed by a scanning electron microscope. The evaluation results are shown below. A: No grinding flaw, good B: Insufficient amount of grinding, bad C: Grinding flaw, bad

Examples 2 to 3 and Comparative Examples 1 to 2 Emulsion polymerization was carried out in the same manner as in Example 1 except that the amounts of various monomers and emulsifiers were changed as shown in Table 1 to produce various polymer fine particles. did. Using the various polymer fine particles obtained, a polishing layer coating solution was prepared in the same manner as in Example 1, and the state of the polished surface was evaluated in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 3 A polishing layer coating solution was prepared in the same manner as in Example 1 except that no polymer fine particles were used, and the surface condition of the head polished in the same manner as in Example 1 was evaluated. The results are shown in Table 1.

[0013]

[Table 1] DBSN: Sodium dodecylbenzene sulfonate

[0016]

EFFECT OF THE INVENTION The abrasive material of the present invention provides a smooth magnetic head surface and high finishing accuracy, and is excellent in processing performance.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-1-297487 (JP, A) JP-A-62-88569 (JP, A) JP-A-57-8278 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C08J 5/00-5/24 C09K 3/14

Claims (2)

(57) [Claims] On the 1. A substrate, crosslinking monomers 7-95 fold having a group containing a polymerizable double bond at least two per molecule
Polymerizable Monomer Containing Amount% And Non-Crosslinkable Monomer
Is provided with a layer containing cross-linked polymer particles having an average particle diameter of 0.01 to 2 μm obtained by emulsion polymerization using a surfactant . 2. A crosslinkable monomer having 2 or more groups having a polymerizable double bond in one molecule, 7 to 95% by weight, and
A polymerizable monomer containing a non-crosslinkable monomer is used as an interfacial active agent.
A polishing material obtained by dispersing cross-linked polymer particles having an average particle diameter of 0.01 to 2 μm obtained by emulsion polymerization using a tonicity agent in a dispersion medium.