JPS61246262A - Production of copolymerizable magnetic fluid - Google Patents

Abstract

PURPOSE:To obtain a copolymerizable magnetic fluid suitable for use in the production of magnetic paints, by adding a high-molecular surfactant mainly composed of a maleinized polybutadiene to an aq. suspension of a fine ferromagnetic oxide powder to allow the surfactant to be adsorbed by the surface of the fine powder. CONSTITUTION:A high-molecular surfactant mainly composed of a maleinized polybutadiene (or salt) obtd. by reacting maleic acid with polybutadiene is added to an aq. suspension of a time ferromagnetic oxide powder (e.g. magnetite colloid or ferrite colloid) prepd. by a wet process to allow the surfactant to be adsorbed by a monolayer or built-up layer on the surface of the ferromagnetic oxide powder in the suspension, thus obtaining a copolymerizable magnetic fluid. The resulting copolymerizable magnetic fluid and other polymerizable monomer are polymerized, whereby a film contg. the fine magnetic powder can be easily formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a copolymerizable magnetic fluid.

[Industrial field of application] [Prior art] Long-chain unsaturated fatty acid ions such as oleic acid, linoleic acid, and lyluic acid are adsorbed onto ferromagnetic fine particles such as magnetite and Mn-Zn ferrite, and then either as they are or attached to various interfaces. Magnetic fluids with added activators and stably dispersed in water, kerosene, ester solvents, etc. have been developed, and their applications are being extensively studied. Typical examples of its application development include the following.

0 Sealing effect obtained by placing magnetic fluid in areas where magnetic flux is concentrated.

・Gravity sorting using magnetic buoyancy that acts on non-magnetic substances in magnetic fluid placed under a magnetic field gradient ・Recording materials using magnetism ・Waste oil treatment Many of these have been put into practical use, but their use was limited to those that are liquid and make use of magnetism.

[Problem that the invention seeks to solve]

The present invention maintains the characteristics of conventional magnetic fluids and provides copolymerizability, which conventional magnetic fluids do not have.
When the magnetic fluid of the present invention is used, it is possible to produce an emulsion containing magnetic fine particles as a core or a water-soluble polymer containing magnetic fine particles at the end.

By polymerizing such copolymerizable magnetic fluids with other polymerizable vinyl monomers, it is possible to form films containing magnetic fine particles and obtain magnetic fine particle materials that can be mixed into other materials. becomes. Furthermore, when magnetic fine particles are contained at the end of the water-soluble polymer, movement by a magnetic field becomes possible, and separation and concentration effects using the water-soluble polymer are promoted by magnetic force.

[Means for Solving the Problems] [Operation] In view of the above points, the present invention provides a method for adding a high-density polymer containing maleated polybutadiene or a salt thereof to an aqueous suspension of fine ferromagnetic oxide powder by a wet method. It is characterized in that a molecular surfactant is added and the surfactant is adsorbed to a monomolecular layer or more on the surface of the fine powder in the suspension. The main idea is a method for producing a copolymerizable magnetic fluid.

Details will be explained below.

In the method for producing a magnetic fluid according to the present invention, an aqueous suspension of ferromagnetic fine particles such as magnetite or Mn-Zn ferrite obtained by a wet method is neutralized with ammonia of maleated polybutadiene, an amine, a hydroxide of Narkali metal, etc. A monomolecular layer or more is adsorbed onto the surface of the ferromagnetic fine particles. Thereafter, by utilizing the copolymerizable double bonds of the maleated polybutadiene and copolymerizing it with a polymerizable vinyl monomer, an emulsion containing magnetic fine particles in the core or containing magnetic fine particles at the ends is created. A water-soluble polymer is obtained.

The following maleated polybutadienes are used as the basis of the present invention.

First, polybutadiene, which is a raw material for maleated polybutadiene, has a number average molecular weight of 500 to s, ooo
A polybutadiene preferably having L 000 to 3,000, a butadiene copolymer having the above-mentioned number average molecular weight containing 10% by weight or more, preferably 40% by weight or less as butadiene units, or a modified product of these polymers. preferable. The above polybutadiene may have any structure of 1,2-vinyl type, 1,4-trans type, or 1,4-cis type, and of course may be a partial mixture of these structures. I can't help it.

When the molecular weight of the polybutadiene used is within this range, it is preferable because the viscosity during the maleation reaction is appropriate and the polybutadiene has excellent dispersibility when neutralized after the maleation reaction and used as a polymer emulsifier.

If the molecular weight is larger than this, the viscosity becomes high during the maleation reaction, making handling difficult. In addition, if the viscosity is small, there is no problem in handling, but when the viscosity is neutralized after the maleation reaction and used as a polymer emulsifier, the dispersibility is poor and it cannot be used as a polymer emulsifier.

To maleate these polybutadienes, maleic acid or maleic anhydride is reacted with the polybutadienes. This reaction is carried out by placing polybutadiene in a reaction vessel together with maleic acid or maleic anhydride and, if necessary, a solvent.
This is done by heating to 250°C.

The maleated polybutadiene thus obtained neutralizes the carboxylic acid groups after the maleation reaction when maleic acid is used in the maleation reaction.

On the other hand, when maleic anhydride is used, water, alcohol,
Ring-opened with amine etc. to form dicarboxylic acid half ester,
As a semi-acid compound, the carboxylic acid group is further neutralized.

The acid value of the above maleated polybutadiene is 60 to 30.
A range of 0 is desirable, and when it is within this range, the water solubilizing ability after neutralization is sufficient.

Examples of the neutralizing agent used for neutralizing the carboxylic acid group include ammonia, amines, and alkali metal hydroxides. The amines include primary, secondary or tertiary amines, and diamines.

Polyvalent amines such as triamines can be used.

In this case, the amount of neutralizing agent used is usually 0.2 to 00 g per equivalent of carboxyl group of maleated polybutadiene.
An equivalent amount, preferably 0.3 to 0.7 equivalents, is desirable from the viewpoint of adsorption to magnetic fine particles and dispersibility after adsorption.

〔Effect of the invention〕

As mentioned above, magnetite, Mn-Z, obtained by a wet method using a specific neutralized product of maleated polybutadiene
By adsorbing and dispersing n, magnetic particles such as ferrite, it is possible not only to obtain a magnetic fluid similar to that obtained by using conventional long-chain unsaturated fatty acid ions as a dispersant, but also to obtain By utilizing the bond and copolymerizing with a polymerizable vinyl monomer, it is possible to produce emulsions containing magnetic fine particles in the core or water-soluble polymers containing magnetic fine particles at the ends.

As a result, it is possible to incorporate magnetic fine particles into a part of the polymer, and it is now possible to create magnetic paints and magnetic toners for copying machines, which previously had great difficulty in manufacturing magnetic fine particles and mixing and dispersing them into binder materials. It becomes easy to manufacture such as.

In addition, in the case of water-soluble polymers, it is possible to accelerate the sedimentation rate and dehydration rate and reduce the water content by external magnetic force in the sedimentation and separation action of suspended matter, thus solving the problems associated with the use of water-soluble polymers.

The present invention will be described below based on production examples, examples, and comparative examples. Note that the parts 9% on each side are parts by weight.

Refers to weight%.

[Production Example 1'] Polybutadiene A (number average molecular weight 1.000: 1.
2-vinyl type 91%, 1,4-trans type 9%) 170
2. Maleic anhydride 30? and xylene loomj are sealed in an autoclave, the autoclave is sufficiently purged with nitrogen gas, and the mixture is heated at 170 to 190° C. for 5 hours with stirring at a speed of 90 revolutions/minute to carry out a maleic reaction.

After the reaction, xylene and unreacted maleic anhydride are removed by washing with water. The maleated polybutadiene obtained had a pentavalent value of 122 and a viscosity after dehydration of about 300,000 cps at 730°C. Next, dehydrated maleated polybutadiene 100
9 and 28% ammonia water 9.29 (neutralization equivalent 0.
Add 7) and neutralize with stirring, then add water to adjust the nonvolatile content to 30%.

[Production Example 2'] Polybutadiene B (number average molecular weight 2.000; l,
4-cis 72%, l, 4-trans 27% and 1
．． 175 g of 2-vinyl type 1%), 24 g of maleic anhydride, and a room of xylene were sealed in an autoclave, thoroughly purged with nitrogen gas, and heated at 180 to 200°C for 4 hours while stirring at a speed of 90 rpm. Perform maleation reaction. Wash with reaction water to remove xylene and unreacted maleic anhydride. The resulting maleated polybutadiene had an oxidation rate of 99% and a viscosity of about 47 cps/30°C after dehydration. Next, 100f of the dehydrated maleated polybutadiene is taken, and 8.49 g of a 50% aqueous NaOH solution (neutralization equivalent: 0.6) is added to neutralize it while stirring, and water is further added to adjust the nonvolatile content to 30%.

[Production Example 3'] An aqueous solution of 1 mol each of ferrous sulfate and ferric sulfate was
After adding 3N ammonia water to 2 tons of an aqueous solution mixed so that 2+:Fe8+=1:2 until the pH reached 1000, the mixture was aged at 60° C. for 50 minutes to obtain a magnetite colloid.

[Production Example 4'] Add 1 mol each of manganese sulfate, zinc sulfate, and ferric sulfate to an aqueous solution of Mn2, Zn2, and Fe8 = 0.5:0.
．． Mix in a ratio of 5:2 so that the total amount is 2 tons, and add 6
After adding a NaOH aqueous solution of N while stirring until the pH reached 1000, the solution temperature was set to 80°C and aged for 10 minutes.
A colloid of Mn-Zn ferrite was obtained.

[Example 1'] Magnetite colloid O, St produced by the wet method of Production Example 3
A 30% aqueous solution 701 of the ammonia-neutralized maleated polybutadiene obtained in Production Example 1 was gradually added to the mixture at a liquid temperature of 80°C, and after the addition, the adsorption reaction was continued at the same temperature for 3 hours with stirring. The obtained liquid was a stable magnetic fluid, and no supernatant or sedimentation occurred even after being left at room temperature for one week.

In the case of the conventional method using long-chain unsaturated fatty acids, the amount of carboxylic acid involved in the adsorption reaction is 1 per molecule of long-chain unsaturated fatty acids.
Therefore, in order to complete adsorption and dispersion, the pH is adjusted to acidic after adsorption, the suspension is coagulated, and washing is repeated to obtain magnetite or Mn-Zn ferrite long-chain unsaturated fatty acids. Generally, a stable magnetic fluid is obtained by separating a monomolecular layer of adsorbed material with a lipophilic interface and adding various surfactants to the monomolecular layer of adsorbed material having a lipophilic interface. Ta.

On the other hand, in the case of the maleated polybutadiene used in the present invention, one molecule contains multiple carboxylic acids, so if a sufficient adsorption reaction is carried out, the carboxylic acids involved in dispersion can also be integrated. Since adsorption and dispersion can be done in one step, there is no need to separate the adsorption reaction and dispersion operation, as is the case with long-chain unsaturated fatty acids.

However, in this case, the basis for obtaining a magnetic fluid is chemical adsorption of carboxylic acid onto magnetite or Mn-Zn ferrite, so the adsorption capacity (neutralization equivalent) of the maleated polybutadiene used is important. The neutralization equivalent is somewhat small from the viewpoint of adsorption, but from the viewpoint of dispersibility it is desirable that it be large, and it is necessary to balance the two, and it is 0.3 to 0.7
Preferably.

Furthermore, in the case of the present invention, the obtained magnetic fluid contains double bonds derived from polybutadiene, and copolymerization with other polymerizable vinyl monomers is possible using these double bonds. It is possible to produce emulgene particles containing magnetic fine particles in the core and water-soluble polymers containing magnetic fine particles at the ends.

[Example 2'] To 0.5 t of Mn-Zn ferrite colloid obtained by the wet method of Production Example 4, 80% aqueous solution of 30% NaOH-neutralized maleated polybutadiene obtained in Production Example 2 was gradually added at a liquid temperature of 70°C. After the addition of , the adsorption reaction was continued for 4 hours at the same temperature with stirring. The resulting liquid was a stable magnetic fluid and did not form any supernatant or sediment even after being left at room temperature for one week.

[Comparative Example 1'1 In the production of the neutralized maleated polybutadiene in Production Example I, the neutralization equivalent was set to 1.0, and the magnetite colloid obtained in Production Example 3 was added in the same manner as in Example 1. An adsorption reaction was performed. When the obtained liquid was left at room temperature and its stability was examined, a precipitated portion was formed after 2 days. This is because the neutralization equivalent of the maleated polybutadiene used was high and chemical adsorption onto magnetite did not proceed.

[Comparative Example 2'] The magnetite colloid obtained in Production Example 3 was prepared in the same manner as in Example 1, using the neutralized product of maleated polybutadiene in Production Example 1 with a neutralization equivalent of 0.1. An adsorption reaction was carried out. The obtained liquid was allowed to stand at room temperature, and its stability was examined. After one day, a supernatant portion and a precipitated portion were formed. This is considered to be because the neutralization equivalent of the maleated polybutadiene used was low and the dispersibility was poor. Note that even when an aqueous solution of maleated polybutadiene having a neutralization equivalent of 0 or 1 was used alone, a supernatant portion and a sediment portion were formed upon standing, resulting in insufficient dispersibility.

Claims (1)

[Claims] A polymeric surfactant containing maleated polybutadiene or its salt as a main component is added to an aqueous suspension of fine ferromagnetic oxide powder obtained by a wet method, and the surfactant is applied to the surface of the fine powder in the suspension. A method for producing a copolymerizable magnetic fluid characterized by adsorbing a monomolecular layer or more of .