JPH0435711A - Magnetic filter and production thereof - Google Patents

Abstract

PURPOSE:To effectively capture fine metal particles in a fluid by using a magnetic filter with magnetic powder melt-stuck to synthetic pulp. CONSTITUTION:Magnetic powder such as ferrite powder having <=1mum average particle size, synthetic pulp such as PE pulp having 20mum average diameter 1.2mm average length and 350cc freeness rate (CSF) and short fibers having a high m.p. such as short PP fibers having 2 denier diameter and 5mm length are dispersed in an aq. medium. Paper is made from the resulting dispersion and heat-treated, e.g., at 150 deg.C for 5min to produce a filter. This filter can effectively capture fine metal powder in a fluid by the action of the contained magnetic powder and is useful as a filter for a cooling fluid used at the time of cutting a metal, an oil filter for an automobile or a filter for removing iron in tap water.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a filter, and more specifically,
The present invention relates to a magnetic filter for effectively collecting metal powder in a fluid and a method for manufacturing the same.

(Prior Art and its Problems) A so-called mesh filter is known as a filter for collecting solid particles in a fluid. However, this mesh filter has a problem in that it is not suitable for collecting fine metal powders mixed in solid particles. In other words, in order to collect metal powder with a fine particle size, the collection efficiency cannot be improved unless the mesh size of the filter is made small.
There is a problem in that the pressure loss applied to the filter becomes large and the collection efficiency is significantly reduced.

Therefore, an object of the present invention is to provide a filter that can effectively collect fine metal powder in a fluid.

(Means for Solving the Problems) According to the present invention, there is provided a magnetic filter characterized in that magnetic powder is fused to synthetic pulp.

Further, according to the present invention, magnetic powder, synthetic pulp, and high melting point short fibers are dispersed in an aqueous medium, and the dispersion is made into paper,
A method for manufacturing a magnetic filter is provided, which comprises subsequently performing heat treatment.

Furthermore, according to the present invention, there is provided a method for manufacturing a magnetic filter, which comprises dispersing magnetic powder and synthetic pulp in an aqueous medium, forming the dispersion onto a nonwoven fabric, and then heat-treating the dispersion. Ru.

That is, in the filter of the present invention, magnetic powder is fused and encapsulated in the synthetic pulp that is the filter base material, and metal powder in the fluid is effectively collected by the magnetic force of the magnetic powder. be.

(Preferred Embodiment of the Invention) An important feature in manufacturing the magnetic filter of the present invention is to first disperse magnetic powder, synthetic pulp, and high-melting short fibers in an aqueous medium and then perform papermaking. By doing so, the magnetic powder is adsorbed and retained on the synthetic pulp that serves as the filter base material.

As the magnetic powder, various types such as metal-based, ferrite-based, rare earth cobalt-based, etc. can be used, but ferrite having an average particle size of 1 μm or less is particularly suitable. This ferrite has an average grain size! Since it is less than U, it has a single domain structure and is characterized by spontaneous magnetization.

Further, as the synthetic pulp, one made of thermoplastic resin is suitable, and in particular, a synthetic pulp produced by a solution or emulsion flash spinning method is suitably used. Examples of such thermoplastic resins include hydrophobic thermoplastic resins such as polyolefins, polyesters, and polyacrylonitrile, but particularly polyethylene, polypropylene, ethylene-propylene copolymers, and ethylene-1-butene copolymers. combination, ethylene-4-methyl-1-
1 of ethylene and α-olefin such as pentene copolymer
Polyolefins consisting of one species or two or more species are preferred, and crystalline polyolefins are particularly desirable from the viewpoint of producing a pulp-like product and the mechanical properties of the resulting pulp-like product. Further, the freeness of the synthetic pulp is desirably within the range of Canadian freeness of 400 cc or less. If it exceeds 400 cc, it may become difficult for the synthetic pulp to attract and hold magnetic powder.

Although synthetic pulp can be used alone, the desired effect can also be achieved by using a wood pulp/synthetic pulp co-beating product. This co-beating product has a high freeness and is therefore characterized in that it can effectively adsorb and retain magnetic powder.

In the present invention, the high melting point short fibers function as a reinforcing material, and are short fibers of a resin that has a melting point or decomposition temperature (in the case of a thermosetting resin) higher than the melting point of the resin of the synthetic pulp used. , usually with a fiber length of 2 to 30
rxm, preferably 5 to 20 mm, and a fiber diameter of 1 to 1000 μm, preferably 2 to 200 μm, is suitably used. Further, a sheath-core type composite fiber in which the core portion has a high melting point and the sheath portion has a low melting point can also be used in place of the high melting point short fibers.

When dispersing magnetic powder in an aqueous medium such as water, it is desirable to use a dispersant.

As the dispersant, various anionic, cationic, and nonionic surfactants can be used, and oleic acid-based anionic surfactants are particularly suitable. This dispersant is usually 0.0 to 5.0% by weight per magnetic powder.
used at a rate of

In addition, the amounts of magnetic powder, synthetic pulp, and high melting point short fibers used are based on the weight, and the magnetic powder 2-containing pulp: high melting point short fiber =
The ratio is preferably 5 to 90:5 to 90:5 to 50.

Furthermore, in papermaking, it is desirable to add a flocculant to the above dispersion. Thereby, the fixing rate of magnetic powder to synthetic pulp can be further improved. As the flocculant, polyacrylamide-based or polyacrylic acid-based ones are preferred, and polyacrylamide-based ones are particularly preferred. The amount of flocculant added is generally 0.00% per dispersion. old to 5.0% by weight, preferably 0.0
The proportion is preferably 5 to 2.0% by weight.

Further, latex may be added to the dispersion liquid in order to reinforce the bond between the magnetic powder and the synthetic pulp. Suitable examples of such latex include polyvinyl acetate-based and styrene-butadiene-based latexes.
Usually, the dispersion is added in a proportion of 20% by weight. Paper making is carried out by a method known per se, and methods such as the Fourdrinier method and the cylinder method can be employed. In this case, paper may be made on the nonwoven fabric to integrate the synthetic pulp to which the magnetic powder is fixed and the nonwoven fabric. Since the nonwoven fabric at this time functions as a backup reinforcing material, there is no particular need to use high melting point short fibers in this case. As this nonwoven fabric, a nonwoven fabric of a resin having a melting point or decomposition temperature (in the case of a thermosetting resin) higher than the melting point of the resin of the synthetic pulp used is used, and any method such as spunbond method, melt blowing method, carding method, etc. However, from the viewpoint of strength, it is preferable to use a nonwoven fabric manufactured by a spunbond method. The basis weight is 5 to 200g/m2, especially 1
A range of 0 to 50 g/m2 is preferred.

After papermaking, heat treatment is performed to melt the synthetic pulp and fuse the magnetic powder to it. This heat treatment is carried out in a temperature range above the melting point of the synthetic pulp and below the melting point or decomposition temperature of the high-melting short fibers or nonwoven fabric. The heat treatment can be carried out using, for example, a hot air blower type device that blows hot air, or a floating type device that allows the hot air to pass between heat sources.

The filter manufactured in this manner has a structure in which magnetic powder is fused and encapsulated in synthetic pulp, which is the main material of the filter.

(Effects of the Invention) The filter of the present invention can effectively collect fine metal powder in a fluid due to the action of the magnetic powder contained therein, and can be used, for example, as a cooling fluid during metal cutting. Filter used: Extremely useful as an automobile oil filter and a filter for removing iron from tap water.

(Example) Hereinafter, the present invention will be explained in detail with reference to Examples.

Actually, 1 case.

The following materials were used as raw materials.

Polypropylene short fiber (PP short fiber); fiber diameter 2 denier, fiber length 5 mm, manufactured by Chisso ■, product name P-Ch
OP Polyethylene (PE) synthetic pulp; average fiber diameter 20 μ, average fiber length 1.2 mm, freeness (CSF) 350 cc Magnetic powder; 50% concentration slurry interface of Sr/ferrite powder (average particle size 1 μ) 1% sodium oleate used as activator (per ferrite) 0.94g of the above PP short fibers, 0.9g of PE synthetic pulp
4g and 0.5g of magnetic powder, 2! The mixture was stirred and mixed in water 2I2 using a JIS type pulper. The stirring time is 60 seconds and the water temperature is room temperature.

Next, the mixture was made into paper using a rectangular paper machine with a size of 25 x 25 cn+, dried, and heated at 150° C. for 5 minutes in a circulating hot air dryer.

As a result, it was possible to obtain a filter in which the magnetic powder was fused and bonded with the PE synthetic pulp and had voids throughout.

This filter sample was set in a funnel, and water containing iron oxide powder (particle size of 2 μm or less) was poured thereinto to perform filtration, and the impurity concentration of the filtrate was measured.

The results are shown in Table 1.

1 seed ■ 1 WP (NUKP, softwood unbleached kraft pulp) and
A PE synthetic pulp with an average fiber diameter of 20μ, an average fiber length of 1.5++s, and a freeness (CSF) of 500cc.
After mixing at a ratio of 15 to 15, the pulp was beaten in a disc refiner to obtain a beaten WP/PE synthetic pulp having a freeness (C3F) of 20 cc.

0.31 g of this beaten material and 0.0 g of the magnetic powder used in Example 1.
．． 31 g were stirred and mixed under the same conditions as in Example 1 to prepare a mixed solution.

Next, a non-woven fabric (pp-spun pound, basis weight 20g/I
I+") was placed thereon, and the above-mentioned mixed solution was poured onto it to perform paper making. Further, it was dried under the same conditions as in Example 1 to obtain a filter.

In this filter, the magnetic powder was well fused to the nonwoven fabric by the synthetic pulp.

In addition, a performance test of the filter was conducted in the same manner as in Example 1, and the results are shown in Table 1.

Using the same WP and PE synthetic pulp as in Example 2,
P/PE synthetic pulp (3/7) cobeat product (CSF =
30cc) was obtained.

A nonwoven fabric (
A filter was obtained by making paper on a pp-spun ind, fabric weight 20 g/m" and drying.

A filter performance test was conducted on this filter in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Examples 1 to 3 In each Example, filters of Seven Comparative Example I Samples 1 to 3 were obtained in the same manner as in each Example except for using uXel, which did not use magnetic powder.

A filter performance test was conducted on these comparative samples in the same manner as in Example 11 (/X), and the results are shown in Table 1.

Table 1

Claims (4)

[Claims] (1) A magnetic filter characterized in that magnetic powder is fused to synthetic pulp. (2) The method for producing a magnetic filter according to claim 1, characterized in that the magnetic powder, synthetic pulp, and high-melting short fibers are dispersed in an aqueous medium, the dispersion is made into paper, and then heat treatment is performed. (3) The manufacturing method according to claim 2, wherein a wood pulp/synthetic pulp co-beating product is used instead of the synthetic pulp. (4) The method for manufacturing a magnetic filter according to claim 1, characterized in that the magnetic powder and synthetic pulp are dispersed in an aqueous medium, the dispersion liquid is made into paper on a nonwoven fabric, and then heat treatment is performed.