JPS61204215A - Graft composite material - Google Patents

Abstract

PURPOSE:The titled composite material useful as a magnetic material, magnetic recoding material, microwave material, etc., having improved dispersibility into solvents, resins, obtained by subjecting a monomer containing an N- vinylcarbazole compound to cobalt oxide powder. CONSTITUTION:A monomer containing preferably 30-100mol% N-vinylcarbazole compound is subjected to graft polymerization onto cobalt oxide powder (e.g., CoO, Co2Ba2Fe24O41, CoCr2O4, CoFe2O4, CO<2+>Fe2<3+>O4, Co0.8Fe2.2O42CoMn2O4, Co0.1Ni0.9Fe2O4, Co<2+>TiO3, Co0.32Zn0.22Fe2.2O4, etc.), to give the aimed composite material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a graft composite obtained by graft polymerizing a monomer containing an N-vinylcarbazole compound to a cobalt oxide powder.

[Prior art l] Conventionally, cobalt oxide powder has been used in various materials that take advantage of its ferromagnetic properties, such as magnetic materials, magnetic recording materials, etc.
It is used for many purposes such as microphone A-wave materials and varistor materials.

Cobalt oxide powder can be shaped into a film, for example.
When used in sheet, block, etc.
Usually, it is used by mixing cobalt oxide powder with resin and coating it on a substrate or molding it in a mold.

[Problems to be solved by the invention] When trying to mix resin to mold cobalt oxide powder, it is difficult to mix uniformly (for example, even if dispersed with a disperser, it is difficult to monodisperse). However, there is a problem that even if monodispersed, it will soon aggregate.

The present invention was made in order to solve the above-mentioned problems that occur when cobalt oxide powder is mixed with a resin.

[Means for Solving the Problems 1] The present invention provides that when an N-vinylcarbazole compound is brought into contact with a cobalt oxide powder in a solution, the N-vinylcarbazole compound polymerizes and grafts onto the copal II compound powder. It was made based on the discovery that when a composite is made and another vinyl monomer is present at the same time as an N-vinylcarbazole compound, a composite in which a copolymer is grafted can be obtained. The present invention relates to a graft composite obtained by graft polymerizing a monomer containing an N-vinylcarbazole compound to cobalt oxide powder.

[Example] The cobalt oxide powder used in the present invention is Coo, Co
2Ba3Fez<0<Is CoCr2O4, CoF
ezO4, Co”◆Fe KO◆01, Coo, sFe*,
i0n*CoHn204, Co, ), lN1o, Jez
04, Co”◆Tie,, COOe 32 Z n O
* 22 Fe 2 m 204 etc. Cobalt-based oxide or cobalt or a metal whose main component is cobalt as a base, and 30 to 100% of the surface,
Preferably, the powder is 80 to 100% oxide.

The monomer containing tovinylcarbazole compound used in the present invention refers to tovinylcarbazole M (several mol% to
100 mol%, preferably 30 to 100 mol%, and other monomer components such as methyl tuacrylate, ethyl methacrylate, methyl acrylate, acrylonitrile, methacrylonitrile, vinyl acetate, styrene, etc. -Contains a component that can be copolymerized with a vinylcarbazole compound.

Specific examples of the N-vinylcarbazole compounds include N-vinylcarbazole, where one or more hydrogen atoms in the benzene ring part of the N-vinylcarbazole skeleton are substituted with a chlorine atom, a bromine atom, a heptadium atom, etc. N
-vinylcarbazole derivatives, etc.

The graft composite of the present invention has N-
It can be obtained by graft polymerizing monomers containing vinyl carbazole compounds. In addition, the graft complex referred to in this specification is a compound containing a tovinylcarbazole compound in the surface oxide produced when a monomer containing an N-vinylcarbazole compound is polymerized in the presence of the powder. This concept refers to a composite made of monomers grafted together.

The graft complex is usually fabricated by contacting a monomer containing a tovinylcarbazole compound with cobalt oxide powder in a solvent.

Since polymerization is proportional to the specific surface area of the powder, the larger the specific surface area, the more quickly polymerization will proceed. Therefore, if the specific surface area of the powder is less than 0.11"/g, polymerization will be difficult to proceed.

Graph of N-vinylcarbazole-based compounds to cobalt oxide) Once polymerization has begun, it has the ability to initiate polymerization of other monomers that do not polymerize in the presence of cobalt oxide powder. Therefore, if you want to polymerize even if other monomers, such as vinyl monomers, are contained, and you want to polymerize mainly with other monomers, use a small amount of N-vinylcarbazole compound, and use the powder The polymerization may be initiated in the presence of the N-vinylcarbazole compound, and other monomers other than the N-vinylcarbazole compound may be subsequently polymerized.

If these other monomers dissolve N-vinylcarbazole, they may be polymerized without a solvent.

The solvent used during polymerization may be any solvent as long as it does not dissolve N-vinylcarbazole and interfere with the polymerization (e.g., aromatic hydrocarbon solvents such as toluene and benzene, alicyclic hydrocarbon solvents such as cyclohexane, etc.). Examples include solvents, nityl solvents such as tetrahydrofuran, and the like.

The polymerization is preferably carried out by raising a monomer solution of several percent to 100 percent containing a tovinylcarbazole compound to a predetermined reaction temperature, for example, 60 to 110°C, in the presence of cobalt oxide powder. In this way, a graft complex of cobalt oxide powder and a monomer containing an N-vinylcarbazole compound is obtained.

The ratio of the monomer component containing the N-vinylcarbazole compound to the cobalt oxide powder during polymerization is preferably 17,100 or more by weight.0 Polymerization yield means an increase in the amount of monomers used Therefore, when the ratio is less than 17,100, grafting that causes surface modification of the cobalt oxide powder is difficult to occur.

The polymerization reaction can be stopped by adding something that stops ionic polymerization, such as methanol.

A well-crafted graft composite has good dispersibility in solvents such as toluene, and by using such a composite, it can be mixed uniformly with resin, creating a uniform film, sheet, or You can make block moldings. *By appropriately selecting the copolymerization components, it is possible to make a thermoplastic graft composite material, which makes bulk molded products lighter and lighter.

Since the film, sheet or molded product thus obtained has the properties of cobalt oxide powder, it can be used for many purposes such as magnetic materials, magnetic recording materials, microwave materials, and varistor materials.

Next, the graft composite of the present invention will be explained based on Examples.

Example 1 6 g of copal oxide with an average particle diameter of approximately 1 μm and a specific surface area of 1 m” (7 g) was placed in a 200 ml triangular 7 flask and dried at 80° C. for 8 hours in a vacuum dryer.To this was added 20 g of toluene.
ml was added to suspend the cobalt oxide powder.

6 g of tovinylcarbazole was dissolved in this, heated to 90° C., and polymerized for 6 hours with stirring. After methanol Loom& was added to this to stop the polymerization, Soxhlet extraction was performed with methanol for 24 hours, and the polymerization yield was determined to be 7%.

The resulting product was subjected to Soxhlet extraction with benzene for 24 hours to determine the grafting rate, which was 2%. FTI of the obtained composite surface
When analyzed using R, absorption based on N-vinylcarbazole polymerized at 1483ci+-' and 1452em-' was observed. A part of the complex also showed stable colloidal dispersion. It is believed that only 90% of the fine particles of the oxide powder used exhibited this characteristic, and that this would not occur with larger particles.

The obtained composite is mixed with a methyl methacrylate solution and a polystyrene solution so that the solid content polymerization ratio is 171, and is uniformly dispersed to produce a film with a thickness of 3 μm, resulting in a non-composite cobalt oxide powder. In both cases, the tensile strength was approximately twice as strong as that of the film using the same method.

[Effects of the Invention] The graft complex of the present invention has good dispersibility in solvents, is stably dispersed in resins or resin solutions, and can be highly packed, so it can be easily applied to resins, etc. It is possible to uniformly mix the particles into a dispersion having uniformly dispersed particles, and as a result, it is possible to easily form a coating or sheet with strong mechanical strength. *Can also scale molded objects. Therefore, it can be suitably used in fields such as magnetic materials, magnetic recording materials, microwave materials, and varistor materials.

Claims (1)

[Claims] (1) A graft composite obtained by graft polymerizing a monomer containing an N-vinylcarbazole compound to a cobalt oxide powder.