JPH0381373A - Production of coating material containing fine powder - Google Patents

Abstract

PURPOSE:To allow fine powders to be well dispersed in a coating material by dispersing them in a solvent, predispersing them with a rotary sparger, further dispersing them with a dispersion mill for effecting mixing and dispersion by crushing with the use of beads filled in a container, and mixing and dispersing the fine powders thus treated and a solvent containing a binder component. CONSTITUTION:A coating material containing fine powders is prepared by dispersing them in a solvent, predispersing them in a rotary sparger for effecting mixing and dispersion by rotating a propeller or a disk in a container, further dispersing them with a dispersion mill, e.g. a sand mill, for effecting mixing and dispersion by crushing with the use of beads filled in a container, and mixing and dispersing the fine powders thus treated and a solvent containing a binder component. It is preferable to deposit a surface treatment, such as an aluminum compound or a coupling agent, on the surfaces of the fine powders before the addition of the binder component. Examples of the fine powders include magnetic powder, alumina, silica, chromium oxide, carbon black and red iron oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a paint containing fine powder, and more particularly to a method for producing a paint in which fine powder is extremely well dispersed.

[Conventional technology]

In general, paints containing powder are prepared by mixing and dispersing the powder in a solution containing a binder component, and magnetic paints containing magnetic powder are prepared by mixing the binder component with a solution of an organic solvent and then kneading the powder first. After kneading with a sand mill, it is subsequently dispersed with a sand mill or the like.

[Problem to be solved by the invention]

However, if the powder is relatively large with a particle size of 0.5 μm or more, or if it has not undergone calcination or thermal reduction during the powder production process, homogeneous particles can be sufficiently dispersed using a rotary dispersion machine such as a mixer or disperser. Even if they can be dispersed, fine powders with a particle size of 0.5 μm or less and magnetic powders are heat-treated during the manufacturing process, and the finer they become, the more likely they are to form strong aggregates between particles. cannot be dispersed well even after kneading in a kneader and dispersing process in a sand mill, and the dispersion efficiency is also poor.As a result, dispersion takes more and more time when mass production is achieved, and realistically, There is a drawback that a large amount of time cannot be spent on dispersion, resulting in poor dispersion.

[Means for Solving the Problems] This invention was made as a result of various studies in view of the current situation, and consists of dispersing fine powder in a solvent, and then rotating the propeller or disk in a container. The fine powder is pre-dispersed using a rotary dispersion machine that mixes and disperses the powder, and is then crushed using beads filled in a container. By mixing and dispersing using a dispersion machine such as a sand mill, the fine powder is dispersed in the paint very well and efficiently, and the paint formed by applying a paint in which the fine powder is extremely well dispersed. The mechanical properties of the coating film are sufficiently improved by uniformly and densely filling the film with fine powder. When the fine powder is a magnetic powder, it has sufficiently improved electrical properties as well as mechanical properties.

In addition, after the beads filled in a container are crushed and dispersed in a dispersion machine that mixes and disperses, the surface of the fine powder is By adding and mixing a treatment agent and applying the surface treatment agent to the surface of the fine powder, the dispersion of the fine powder in the paint is further improved, and the mechanical properties of the paint film are further improved. be. When the fine powder is a magnetic powder, the mechanical properties as well as the electrical properties are further improved.

In the preparation of a paint containing fine powder in this invention, after dispersing the fine powder in a solvent, it is first placed in a rotary dispersion machine that mixes and disperses by rotating a rotating body at high speed in a container such as a homomixer or disper. The powder is then dispersed in a dispersion machine that mixes and disperses by crushing it with beads filled in a container such as a sand mill, so fine powder with a particle size of 0.5 μm or less is sufficiently well and efficiently dispersed. It does not require long-term dispersion, even when particles tend to agglomerate due to heat treatment, thermal reduction, etc. during the synthesis process, or bind between particles due to surface coating agents, etc., such as magnetic powders. , the aggregates are uniformly and highly dispersed.

By further mixing binder components, etc., and then dispersing using a kneader or sand mill, a paint in which fine powder is dispersed extremely well and efficiently can be obtained, and fine colored pigments can be used as fine powder. However, if cosmetics or paints are prepared by mixing and dispersing the necessary ingredients, cosmetics or paints with vivid and deep colors can be obtained, and if this paint is used, the mechanical properties of the vivid and deep colors can be improved. Excellent paint finish. In addition, when magnetic powder is used as a fine powder, the dispersion time is greatly reduced, and a magnetic paint with extremely good dispersion of the magnetic powder is prepared, and this magnetic paint can be applied onto a base film such as a polyester film. When a magnetic layer is formed by using the above method, a magnetic layer with excellent dispersibility and filling properties of magnetic powder can be obtained, and a magnetic recording medium with excellent mechanical and electrical properties can be obtained. Furthermore, when the abrasive is used as a fine powder, the dispersion time is significantly reduced, and an abrasive paint with extremely good dispersion of the abrasive is prepared, and this abrasive paint is applied onto a base film such as a polyester film. When a polishing layer is formed by doing so, a polishing layer with excellent abrasive dispersibility and filling properties can be obtained, and a polishing film with excellent mechanical properties and polishing properties can be obtained.

Dispersion using a rotary dispersion machine, which mixes and disperses by rotating a rotating body at high speed in a container such as a disper or homo mixer, works to disperse lumpy powder into fine aggregates. Dispersion using a dispersion machine, which crushes and mixes and disperses with beads packed inside, depends on the type and form of the fine powder, bead diameter, bead filling rate, vessel internal volume,
It is preferable to optimize conditions such as disk diameter, disk rotation speed, slurry discharge speed, slurry residence time, temperature, etc. By adjusting these conditions appropriately, it is possible to efficiently loosen powder aggregates and maintain an overdispersed state. You can prevent this from happening. These condition settings are determined by calculations in advance, but they also depend on the type and shape of the material, so
In reality, it is best to determine the final conditions through experimentation.

In this way, following dispersion using a rotary disperser that mixes and disperses by rotating a rotating body at high speed in a container such as a homomixer or disper, the mixture is further crushed and mixed using beads filled in a container such as a sand bowl. When the fine powder dispersed by the dispersing machine is subjected to surface treatment by adding and mixing a fine powder surface treatment agent, the fine powder is already well dispersed, so the surface treatment by the fine powder surface treatment agent is performed. The treatment is carried out easily and satisfactorily, and the surface treatment agent is uniformly and satisfactorily adhered to the surface of the fine powder.

The surface treatment agent used for surface treatment of such fine powders includes at least one selected from inorganic compounds such as aluminum compounds, silicon compounds, chromium compounds, and boron compounds, surfactants, coupling agents, and organometallic compounds. Compounds consisting of one kind are preferably used, and when these surface treatment agents are applied to the particle surface of the fine powder, the affinity with the binder component of the fine powder is improved,
For example, in the case of fine powder such as metallic iron powder, which has an extremely active surface, the surface activity is moderated to prevent agglomeration of the fine powder, thereby further improving the dispersibility of the fine powder.

Therefore, the colors of cosmetics or paints obtained by using colored pigments that have been surface-treated with such surface-treating agents in the form of fine powders will be more vivid and deep, and if painted using this paint, the color tone will be improved. Painted with vivid, deep colors and excellent mechanical properties. In addition, by using magnetic powder that has been surface-treated with a surface treatment agent, a magnetic paint with even higher dispersibility of the magnetic powder can be prepared, and this can be applied onto a base film such as a polyester film to form a magnetic layer. By forming this, a magnetic recording medium with significantly superior mechanical and electrical properties can be obtained. Furthermore, if an abrasive whose surface has been treated with a surface treatment agent is used, an abrasive paint with even greater dispersibility of the abrasive can be prepared, and this can be applied onto a base film such as a polyester film to form an abrasive layer. By forming this, a polishing film with excellent mechanical properties and polishing properties can be obtained. The amount of such surface treatment agent applied to the fine powder is preferably less than that which covers the first layer on the surface of the particles, but it may be more than that.

As the fine powder, magnetic powder with a particle size of 0.25 μm or less, and non-magnetic fine powder such as aluminum, silica, chromium oxide, carbon black, and red iron are suitably used. For example, 7-Fe, O,
Fine powder, Fe50. Fine powder, Co-containing 1-Fe, O, fine powder, CO-containing Fe5oa fine powder, Cry, fine powder, F
e fine powder, Co fine powder, Fe-Co-Ni alloy fine powder,
Fe-Ni alloy fine powder, Fe-Co alloy fine powder, G.

Any magnetic powder that is generally used in magnetic recording media, such as -Ni alloy fine powder or barium ferrite fine powder, can be used.

〔Example] Next, embodiments of the invention will be described.

Example 1 Long sleeves are 0.25 μm, needle ratio is 1/10, and coercive force is 90
C with 0 oersted and saturation magnetization of 75 en+u/g
5 kg of 7-Fezo3 fine powder containing 7-Fezo3 was placed in 24 kg of isopropyl alcohol, dispersed for 2.5 hours using a homoxa, and then this suspension was dispersed using a sand mill. For dispersion with a homomixer, use a Homomixer SL model manufactured by Tokushu Kika Kogyo Co., Ltd., with a propeller rotation speed of 800 Orp.
Dispersion in a sand mill was carried out using a sand mill with a capacity of 21. NF glass beads with a diameter of 1.68a++ were filled in the vessel at a bead filling rate of 80% by volume, the disk peripheral speed was 1800 rpm, and the discharge rate was 400 cc/mm. n+i
I went with n.

Next, this slurry was filtered and dried under reduced pressure at -60''C, then magnetic powder and additives were added to a vinyl chloride-vinyl acetate binder resin solution, kneaded in a kneader, and further diluted with a solvent. , perform sand mill dispersion, and finally lubricant,
Gerethane binder resin and crosslinking agent were added and mixed and dispersed to prepare a magnetic paint.

This magnetic paint was applied to a polyester film with a thickness of 14 μm to a dry thickness of 3.5 μm, dried to form a magnetic layer, and then calendered and cut to a predetermined width to create a magnetic tape. .

Example 2 In the preparation of the magnetic paint in Example 1, the major axis was 0.
25μm, needle ratio 1/10. CO-containing 7-F with a coercive force of 9°O oersted and a saturation magnetization of 75 emu/g
Examples except that the same amount of metallic iron powder with a long axis of 0.20 am, an acicular ratio of 1/8, a coercive force of 155 oersted, and a saturation magnetization of 130 emu/g was used instead of the etOa fine powder. A magnetic paint was prepared in the same manner as in 1, and a magnetic tape was made.

Example 3 6 kg of Alyosu fine powder with a particle size of 0.5 μm and a specific surface area of 5 rrr/g was placed in 25 kg of isopropyl alcohol, dispersed for 2.5 hours using a homomixer, and then dispersed in this suspension. The liquid was dispersed using a sand mill. Dispersion using a homomixer was carried out using Homomixer SL model manufactured by Tokushu Kika Kogyo Co., Ltd. at a propeller rotation speed of 800 rpm. Dispersion using a sand mill was performed using a sand mill with a capacity of 21, and zirconia beads with a diameter of 2 m were used. The vessel was filled with beads at a filling rate of 80% by volume, and the disk circumferential speed was 1800 rpm.
The discharge rate was 400 cc/win.

Next, this slurry was filtered and dried under reduced pressure at -60''C, and then added to a vinyl chloride-vinyl acetate binder resin solution.
This fine alumina powder was added and kneaded in a kneader, further diluted with a solvent, and then dispersed in a sand mill.Finally, a lubricant, a urethane binder resin, and a crosslinking agent were added and mixed and dispersed to prepare an abrasive paint.

This abrasive paint was applied onto a 12 μm thick polyester film to a dry thickness of 5 μm, dried to form an abrasive layer, and cut to a predetermined width to produce an abrasive tape.

Example 4 Long sleeves are 0.20 μm, needle ratio is 1/8, and coercive force is 155
0 oersted, 5 kg of metallic iron powder with a saturation magnetization of 130 emu/g was suspended in 24 kg of isopropyl alcohol, and dispersed in a homomixer for 2.5 hours while aerating argon gas to eliminate the influence of air oxidation. This suspension was then dispersed using a sand mill. Dispersion using a homomixer was carried out using a Homomixer SL model manufactured by Tokushu Kika Kogyo Co., Ltd., at a propeller rotation speed of 800 rpm.Dispersion using a sand mill was performed using a sand mill with a capacity of 21 mm and a diameter of 1 mm. The vessel was filled with 68 mm NF glass beads at a bead filling rate of 80% by volume, and the disk circumferential speed was 1800 r.
The p-1 discharge rate was 400 cc/nl1n.

Next, while aerating argon gas to eliminate the influence of air oxidation, 18 kg of isopropyl alcohol was added to the slurry after dispersion and mixed with a propeller stirrer. CH
a0)43i) 270 inl was added and stirring continued for an additional 30 minutes. Then, the temperature of the slurry was gradually raised to 60°C, and stirring was continued for an additional 60 minutes. Then add 40 r! to this slurry. 1
120011 t1 of pure water was added dropwise at a dropping speed of ft/a+in, and after the addition was completed, the mixture was aged for 4 hours with stirring. Thereafter, the slurry was filtered and vacuum dried at 80°C to obtain metal iron powder with a silicon compound coated on the surface. The amount of silicon compound deposited on this metallic iron powder is Si/F
It was 1% by weight in terms of e.

Next, using metal iron powder with a silicon compound coated on its surface, this metal iron powder is placed in a vinyl chloride-vinyl acetate binder resin solution, kneaded in a kneader, and further diluted by mixing with a solvent. Then, the mixture was dispersed in a sand mill, and finally, a lubricant, a urethane binder resin, and additives were added and mixed and dispersed to prepare a magnetic paint.

This magnetic paint was applied onto a 12 μm thick polyester film to a dry thickness of 4 μm, dried to form a magnetic layer, calendered and cut to a predetermined width to produce a magnetic tape.

Example 5 6 kg of Algosu fine powder with a particle size of 0.5 μm and a specific surface area of 5 m/g was placed in 25 kg of isopropyl alcohol, dispersed for 2.5 hours with a homomixer, and then this suspension was dispersed with a sand mill. Dispersion with a homomixer was performed using a Homomixer SL type manufactured by Tokushu Kika Kogyo Co., Ltd. at a propeller rotation speed of 8000 rpa+. Dispersion with a sand mill was performed using a sand mill with a capacity of 2i, with a diameter of 2.
m zirconia beads at a bead filling rate of 80 in the vessel.
The filling was performed at a disk peripheral speed of 1800 rpm+ and a discharge speed of 400 cc10+in.

Next, while aerating argon gas to eliminate the influence of air oxidation, 18 kg of isopropyl alcohol was added to the slurry after dispersion and mixed with a propeller stirrer. CH
30), S i ) 30d were added and stirring continued for an additional 30 minutes. Then, the temperature of the slurry was gradually raised to 60°C, and stirring was continued for an additional 60 minutes. Then, add 40 lll1/1fi to this slurry.
100 ml of pure water was added dropwise at a dropping speed of 1.5 in. After the addition was completed, the mixture was aged for 4 hours with stirring. Thereafter, the slurry was filtered and vacuum dried at 80°C to obtain fine alumina powder with a silicon compound coated on its surface. The amount of the silicon compound deposited on this Al fine powder was 2% by weight in terms of St/Al.

Next, using fine alumina powder coated with a silicon compound on the surface, the fine alumina particles are placed in a vinyl chloride-vinyl acetate binder resin solution and kneaded with a kneader, and then diluted by mixing with a solvent. Thereafter, the mixture was dispersed in a sand mill, and finally, a urethane binder resin and additives were added and mixed and dispersed to prepare an abrasive paint.

This abrasive paint was applied onto a 12 μm thick polyester film to a dry thickness of 5 μm, dried to form an abrasive layer, and cut to a predetermined width to produce an abrasive tape.

Comparative Example 1 A magnetic paint was prepared in the same manner as in Example 1, except that the sand mill dispersion of the magnetic powder was omitted in the preparation of the magnetic paint, and a magnetic tape was made.

Comparative Example 2 A magnetic paint was prepared in the same manner as in Example 2, except that the sand mill dispersion of the magnetic powder was omitted in the preparation of the magnetic paint, and a magnetic tape was made.

Comparative Example 3 An abrasive paint was prepared in the same manner as in Example 3, except that the sand mill dispersion of fine alumina powder was omitted in the preparation of the abrasive paint, and an abrasive tape was made.

Comparative Example 4 A magnetic paint was prepared in the same manner as in Example 4, except that the sand mill dispersion of the magnetic powder was omitted, and a magnetic tape was made.

Comparative Example 5 An abrasive paint was prepared in the same manner as in Example 5, except that the sand mill dispersion of the alumina fine powder was omitted in the preparation of the abrasive paint, and an abrasive tape was made.

The durability, RF output, and surface finish of the magnetic tapes and abrasive tapes obtained in each Example and Comparative Example were examined using the following methods.

Durability> Judgment was made by measuring the time until the output decreases by 3 dB when a still image is reproduced using a commercially available VTR in a constant temperature room at -5°C.

<RF output> After recording a 5MHz signal at a constant level, the output when played back was measured, and the tape of Comparative Example 1 was used as a reference (OdB
) is expressed as a relative value. However, since the magnetic materials of Example 1 and Comparative Example 1 are different from those of Example 2 and Comparative Example 2, in addition to the above relative values, relative values based on Comparative Example 2 are also shown in parentheses.

Surface finish> Wrap the abrasive tape around the circumferential surface of a 5US304φ4 pin at a 90 degree angle, fix one end of the abrasive tape, and apply a load of 20g to the other end, then move the 5US304φ4 pin at a relative speed of 60 The sample was polished by rotating at cm/sec for 1 minute, and the center line average roughness Ra of the surface was measured using a surface roughness meter to examine the degree of surface finish.

Table 1 below shows the results.

Table ■ [Effects of the Invention] As is clear from Table 1 above, the magnetic tapes obtained in this invention (Example 1゜2゜4) are the same as the magnetic tapes obtained in Comparative Examples 1 and 2.4. Therefore, according to the method of the present invention, a paint in which fine powder is dispersed extremely well and efficiently can be obtained, and the paint is a magnetic paint. In this case, it can be seen that as a result of the magnetic powder being dispersed very well and efficiently, the mechanical properties and electrical properties of the magnetic recording medium obtained by applying this magnetic paint are sufficiently improved. In addition, the polishing tape obtained in this invention (Example 3.
5) had a better surface finish than the abrasive tape obtained in Comparative Example 3.5. This shows that according to the method of the present invention, the abrasive was dispersed very well, and as a result, this abrasive paint It can be seen that the abrasive tape obtained by applying the above has sufficiently improved mechanical properties and abrasive properties.

Claims (1)

[Claims] 1. Fine powder is dispersed in a solvent, then predispersed in a rotary disperser that mixes and disperses by rotating a propeller or disk in a container, and then beads filled in the container. Method 2 for producing a paint containing fine powder, characterized in that the fine powder is crushed and dispersed in a dispersing machine for mixing and dispersing, and then the fine powder is mixed and dispersed with a solvent containing a binder component. After dispersing in a dispersion machine that mixes and disperses the particles with beads packed in the powder, before adding a binder component and mixing and dispersing, a fine powder surface treatment agent is added and mixed to coat the surface of the fine powder. 3. A method for producing a paint containing fine powder according to claim 1, wherein the fine powder is a magnetic powder. 4: A method for producing a paint containing fine powder according to claims 1 and 2, wherein the fine powder is a magnetic powder. 5. A method for producing a paint containing a fine powder according to claim 1 or 2, wherein the surface treatment agent for the fine powder is a non-magnetic fine powder such as alumina, silica, chromium oxide, carbon black, or red iron. 3. The method for producing a paint containing fine powder according to claim 2, which is a compound consisting of at least one selected from inorganic compounds such as chromium compounds, boron compounds, coupling agents, surfactants, organometallic compounds, etc.