JPS594169B2 - Lokazainoseizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a filter medium having a dense structure with a density suitable for air purification and lubricant oil purification.

Conventionally, as this type of filter material, a filter material in which a fiber sheet with a thick and thin structure and a fiber sheet with good air permeability are bonded together is known, as shown in Japanese Patent Publication No. 46-23707.

The combination of both fiber sheets forms a portion with a coarser density and a portion with a denser density.

However, the conventional filtration media described above requires a process of bonding different types of fiber sheets together and a process of making each different type of fiber sheet, making the process complicated, making it difficult to mass-produce, and making the filtration media expensive. It has the disadvantage of becoming.

The present invention focuses on the conventional paper-making process in which fibers are dispersed in water and raw materials for filter media are poured onto a net to form a fiber sheet on the net, and the fiber sheet obtained in this paper-making process is dried. It is passed between a pair of previously heated rollers and pressurized, and the uneven surface of the pair of rollers creates a fiber sheet with a thicker part that is a coarser density part and a thinner part that is a denser density part. The object of the present invention is to provide an inexpensive manufacturing method for a filter material that can be mass-produced without the need to separately create different types of fiber sheets as in the conventional method.

The present invention will be explained in detail below.

In Fig. 1, 1 is a fiber sheet whose main raw material is natural fibers such as refined linter and wood pulp, but synthetic fibers for papermaking such as papermaking rayon may be mixed therein. Only synthetic fibers may be used.

This fiber sheet 1 has a thick part 1a and a thin part 1.
b are formed alternately and continuously, resulting in a thick and thin structure.

In the fiber sheet 1 having a thick and thin structure, the thick portion 1a is a low-density portion, and the thin portion 1b is a high-density portion.

This thick and thin fiber sheet 1 contains, for example, a synthetic glue material such as phenol resin, and a natural wood material such as glue, and is hardened by the glue application.

The fibrous sheet 1 having a thick and thin structure thus cured is cut to an appropriate length and folded into a chrysanthemum-shaped cross section, for example, to obtain a filter material.

In the filter medium composed of the fiber sheet 1 having the above-mentioned thick and thin structure, coarse particles are captured in the thick portion 1a,
Fine particles are captured in the thin portion 1b.

When the thinner portion 1b becomes clogged, the pressure loss in this portion 1b gradually increases.

Therefore, the amount of fluid passing through the thick portion 1a increases.

In this way, since the thick portion 1a survives changes in the pressure loss in the filter medium, the pressure loss is increased very slowly without fluctuations in filtration efficiency, and the life of the filter medium is therefore extended.

Next, an example of the manufacturing method of the present invention will be described.

Example A raw material for a filter material (concentration: 01 to 0.2 wt%) of purified linter or wood pulp dispersed in water is poured onto a wire gauze to form a fiber sheet of purified linter or wood pulp on the wire gauze.

As shown in FIG.
As shown in the figure, it is passed between two rollers 3 having a large number of concave portions 3a and convex portions 3b alternately in the longitudinal direction.

This roller 3 has a built-in heater (not shown), so the roller 3 is heated and the fiber sheet 1 is heated.
' is thermoformed and pressed between rollers 3.

The roller 3 forms the fiber sheet 1' into a thick and thin structure by the action of the concave portions 3a and convex portions 3b of the roller 3.

This fibrous sheet 1 having a thick and thin structure is dried with a general drying heat roller 4 used in the paper making process.

After drying, the fiber sheet 1 having a thick and thin structure is impregnated with, for example, a phenol resin and cured.

In the fiber sheet having a thick and thin structure obtained in this example, the air permeability of the thick portion 1a is 1.0 to 1.5 (see /
10φ/300CCair), and the air permeability of the thin part 1b is 2.0 to 2.5 (see/1
0φ/300CCair).

Note that the thickness of the thick portion 1a was 1.4 to 1.7 times the thickness of the thin portion 1b.

In addition, FIG. 4 shows a fiber sheet 1 having a thick and thin structure according to the present invention.
Here is another example of

This differs from the manufacturing method of the above embodiment only in that three fiber sheets 1' formed on the wire mesh 2 in FIG. 2 are stacked.

As described above, the present invention utilizes the conventional papermaking process, and in this papermaking process, a fiber sheet formed on a net is passed between a pair of heated rollers and hot pressed before drying, and the sheet is given a density. Since we have obtained a fiber sheet with a thick and thin structure that has a coarse and fine structure, it is possible to obtain a coarse and fine structure with a high density even without pasting different types of fiber sheets together using the conventional method. It is not necessary to make a fiber sheet, and the manufacturing process is continuous. Therefore, compared to the conventional method, the manufacturing process is simpler, mass production is better, and an inexpensive filter material can be obtained.

In addition, in the present invention, since the fiber sheet before drying obtained in the papermaking process is passed between a pair of heating rollers having unevenness alternately in the longitudinal direction, the fiber sheet is heated while passing between the pair of heating rollers. Since the fiber sheet receives heat from the rollers, the portions that are under pressure from the heating rollers are dried and solidified.

Therefore, the particularly thin part of the fiber sheet that has passed through the pair of heating rollers (the part that has been pressed by the convexity of the rollers) is prevented from attempting to return to its original thickness before passing through the heating rollers due to the repulsive force of the fibers themselves. This makes it possible to reliably form thin, dense parts in the fiber sheet.

Furthermore, in the present invention, since the undried fiber sheet obtained in the papermaking process is continuously passed between a pair of heated rollers,
Even in the case of a long fiber sheet, it is possible to continuously form dense and dense portions over the entire length of the fiber sheet, and therefore the productivity is much better than the method of pressing fiber sheets one by one.

Furthermore, in the present invention, in the pair of heated rollers, the unevenness on one side and the unevenness on the other side are made to face each other, so the fiber sheet can be reliably pressed with the pair of heated rollers, and the fiber sheet is almost never torn. do not have.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a fiber sheet with a thick and thin structure according to the present invention, and FIG. 2 is a process diagram showing an example of the manufacturing process of the present invention.
FIG. 3 is a perspective view showing how the fiber sheet is formed into a thick and thin structure by passing it through the rollers of FIG. 2, and FIG. 4 is a cross section showing another example of the thick and thin structure of the fiber sheet according to the present invention. It is a diagram. 1... Fiber sheet with thick and thin structure, 1a...
・Thick part, 1b...Thin part,
2...Wire mesh forming a net, 3...Roller.

Claims (1)

[Claims] 1 A papermaking process in which a raw material for filter media, in which fibers are dispersed in water, is poured onto a net to form a fiber sheet on the net, and a pair of heating rollers with unevenness alternately in the longitudinal direction are A pre-dried fiber sheet obtained in the papermaking process is continuously passed between the pair of heated rollers, with the concave portions facing the concave portions and the convex portions facing the convex portions, respectively, to press the sheet; A method for manufacturing a filter medium, comprising the step of forming a thick, coarsely dense portion and a thin, densely dense portion in the fiber sheet.