JPH04193315A - Filter having porous layer - Google Patents

Abstract

PURPOSE:To obtain a filter material of long life which collects waste fine particles in a working liquid and prevents clogging of the filter to suppress the pressure loss of the liquid to be filtered by forming a porous resin layer having water permeability on the one surface of nonwoven fabric. CONSTITUTION:On the one surface of an nonwoven fabric 4 having 10-1000g/m<2> weight, a porous resin layer 1 having water permeability is formed by 0. 5-80wt.% of the nonwoven cloth. This porous resin layer 1 is a continuously foamed body obtained by mechanically or chemically foaming a resin. The resin to form the porous resin layer 1 is a thermoplastic or thermosetting resin, containing a water-soluble starch material 3 (e.g. polyvinylalcohol) by 0.05-10wt.% to the solid content of the resin. Thereby, the obtd. filter material has a long life, collects waste fine particles in a working liquid and prevents clogging of the filter to suppress the pressure loss of the liquid to be filtered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an industrial filter medium, and particularly to a filter medium suitable for solid-liquid separation, particularly for wire cutting.

[Conventional technology] Conventionally, metal cutting, especially wire-cut electrical discharge machining, uses a thin wire as an electrode, winds the wire while applying tension, and generates an electrical discharge between the wire and the workpiece.
The workpiece is machined using this discharge energy. At this time, the generated processing waste is sprayed and washed with clean water. This water containing processing waste is sent to a filter by a pump, filtered by a filter medium in the filter, and sent to a clarification tank. The processing fluid that has been purified in the cleaning tank is circulated by a pump and sent to the processing tank.

The electrical discharge machining waste is the worn out workpiece or electrode, and varies in diameter from about 2 to 3 mm to extremely small particles.

For filtration, the minimum particle size to be collected, the pressure drop, and the life of the filter medium are important, but in order to satisfy these three points, it is necessary to increase the filtration area, reduce the filtration speed, and reduce the pore size of the filter medium. . For this purpose, for example, as a filter, a layer of acid clay or activated clay is placed on the surface of a filter cloth made into pleats to increase the wheat area, or rock wool, glass wool, ceramic filters, paper filters, etc. are used. . In recent years, nonwoven fabrics have also been used.

[Problems to be Solved by the Invention] Filters made of non-woven fabric have high filtration efficiency and low pressure loss, but are still prone to clogging due to fine particles. An improved version of this has also been developed in which spunbond nonwoven fabric is laminated to create a multilayer structure, which is then subjected to needling and pressure is applied from the epidermal layer to create a dense surface structure.

However, although filters with this structure have a longer service life than conventional non-woven fabric filters, when using the above-mentioned non-woven fabric filters for wire-cut electric discharge machining, the particle size distribution of the machining fluid is large, so ultra-fine machining in the machining fluid is difficult. Even debris is mainly captured on the surface of the nonwoven fabric, causing clogging, and pressure loss rapidly increases as filtration progresses.

In addition, in the early stages, there was a drawback that processing debris in the form of fine particles in the processing fluid was not primarily captured on the surface of the nonwoven fabric.

The present invention overcomes the above-mentioned conventional drawbacks and problems,
The purpose is to obtain a long-life filter material by reducing the permeation pore diameter of the filter material so as to capture processing waste particles in the processing fluid, preventing clogging of the filter, and suppressing the pressure loss of the filtered fluid. It is something.

;Means for Solving the Problems] In order to achieve the above object, the present invention provides a filter material having a porous layer, characterized in that a porous resin layer having water permeability is formed on one side of a nonwoven fabric, and a filter material having a basis weight of 10 to 1000g#rf
A filter material for growing a porous layer in which a porous resin layer having a water permeability of 0.5 to 80% of the weight of the nonwoven fabric is formed on one side of a nonwoven fabric, and the porous resin layer is formed by mechanically foaming or chemically foaming the resin. The resin forming the porous resin layer of the open foam body is a thermoplastic resin or a thermosetting resin 1, preferably a thermoplastic resin, and an easily water-soluble glue material is added to the resin.

The easily water-soluble adhesive material is polyvinyl alcohol, carboxymethyl cellulose, sodium alginate, starch, or equivalent substances thereof, and the easily water-soluble adhesive material is added in an amount of 0.05 to 50% by weight based on the solid content of the resin. The filter medium has a porous layer.

[For production]

The surface layer of the filter medium made of the open foam of the present invention traps processing debris in the processing fluid to form a cake, and the cake performs a filtering action. When more than a certain amount of cake accumulates on the surface layer of the filter medium, the pressure loss increases rapidly.

On the other hand, fine particles of processing debris are trapped in the pores of the foam and cause clogging, but as time passes, the easily water-soluble glue in the foam dissolves, forming new water holes. Because it is repeated, clogging is less likely to occur, pressure loss does not increase, the filtration flow rate is large, and filtration efficiency is high. That is, the life of the filter medium becomes longer.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a schematic plan view of the filter medium of the present invention, and Fig. 2 is a schematic longitudinal cross-sectional view thereof, in which (1) is an open foam layer, (2) is a foam, and (3) is a resin layer. The dissolved easily water-soluble glue material (4) is a nonwoven fabric layer.

The material of the nonwoven fabric is not particularly limited. Although natural fibers or synthetic fibers may be used, from the viewpoint of durability of the filter medium, it is preferable to manufacture and supply the filter medium by a so-called spunbond method, but other non-woven fabric manufacturing methods may also be used.

Its constituent fibers are general-purpose polyesters (polyethylene terephthalate, polybutylene terephthalate, etc.)
and copolymers thereof, polyamides (nylon 6, nylon 66, etc.) and copolymers thereof, polypropylene, etc. are suitable, but any general-purpose synthetic fiber may be used.

The nonwoven fabric may be produced by partially thermocompressing the web, by a commonly used needle punching method, or by entangling and integrating the web by a water jet entangling method. Here, the water jet entangling method is, for example, Nonwovens world 3 N
o, 2. Also introduced in p. 62-63 (March 1981t).

The thickness of the nonwoven fabric is about 0.1 to 10 mm, and the basis weight is 10 to 1000 g/rri.

Next, the nonwoven fabric is impregnated with a synthetic resin liquid such as acrylic, nipped between heating rollers to squeeze out excess resin liquid, and then dried to impart shape retention, toughness, and filterability.

Thereafter, a mechanically foamable emulsion resin, a water-soluble resin, a foam stabilizer, and a thickener were mixed to prepare a coating liquid. Examples of resins that can form emulsions include vinyl acetate, vinyl chloride, acrylic esters, methyl methacrylate-acrylic ester copolymers, other polyester-based, polyurethane-based, polyamide-based resins or rubbers, and copolymers thereof. It may be. Examples of water-soluble resins include polyvinyl alcohol, carboxymethyl cellulose, and starch.

Dextrin, polyacrylic acid amide, methylcellulose, casein, etc. are used. As the foam stabilizer, higher fatty acid salts such as ammonium stearate are selected, and as the thickener, sodium acrylate and the like are selected.

The above coating liquid is mechanically foamed using an oak mixer or the like, and the resulting composition is 0.5 to 0.5 to
80%, preferably 5-10%, is spread on one side of the non-woven fabric and dried. The foaming ratio of the foaming composition is preferably about 1.5 to 5 times, taking into account the pore diameter and the like. Thereafter, the surface of the foamed resin layer may be pressed with a roll. In this way, a filter medium (5) is formed which has a porous layer having water permeability and an open foam with a smooth surface on its surface so as not to increase the pressure loss of the filter medium.

The filter media is used as shown in FIGS. 3 and 4. Third
The figure is a perspective view of a container housing a filter medium according to an embodiment of the present invention, and FIG. 4 is a sectional view thereof.

The container (6) consists of a cylindrical frame (7),
A filter medium (5) is inserted and fixed inside the container (6), and a cylinder (9) having a hole (8) is inserted into the center of the filter medium (5). The filter medium (5) is numbered in a bellows shape to increase the filtration area. The machining liquid flows from the outside of the frame (7) to the filter medium (
5) may flow into the cylinder (9) while filtering the processed waste, or conversely, it may flow out from the cylinder (9) to the outside and pass through the filter medium (5) while filtering the processed waste. Frame (
7) may be made to flow outside.

Example 1 The present invention will be specifically explained below with reference to Examples.

A polyester spunbond nonwoven fabric with a basis weight of 150 g/m was used as the nonwoven fabric, and needling was performed at a density of 30 threads/cnt.The nonwoven fabric was then impregnated with an acrylic resin liquid, and then nipped with heated rollers and dried. Then, 77 parts by weight of acrylic ester with a solid content of 50% was added with a solid content of 2%.
15 parts by weight of carboxymethylcellulose (15 parts by weight), 5 parts by weight of ammonium stearate (30% solid content) as a foam stabilizer, and 3 parts by weight of sodium acrylate (30% solid content) as a thickener were added to adjust the viscosity to 8000 cps.

The mixed solution was mechanically foamed using an oak mixer, and the foaming ratio was adjusted to 4 times. This foam composition was adjusted to 7% by weight of the non-woven fabric to dry 20 g/m2, knife-coated on one side of the polyester spunbond non-woven fabric at a feed rate of 20 m/min, and heated at 150°C to make the cells in the foam layer continuous. Molded into foam.

Comparative Example 1 A polyester spunbond nonwoven fabric with a date of 150g/lrf was used as the nonwoven fabric, and needling was performed at a density of 30 threads/d.Then, the nonwoven fabric was impregnated with an acrylic resin liquid, and then nipped with heating rollers and dried. . After that, solid content 5
To 77 parts by weight of 0% acrylic ester, 15 parts by weight of carboxymethyl cellulose with a solid content of 2% and 3 parts by weight of sodium acrylate with a solid content of 30% as a thickener were added, and the viscosity was adjusted to 8000 cps. Dry20 g/r by mixing this mixture to 7% by weight of the nonwoven fabric.
RF, one side of the polyester spunbond nonwoven fabric was coated with a knife at a feed rate of 20 m/min, and was heated and molded at 150°C.

Comparative Example 2 A polyester spunbond nonwoven fabric with a date of 150g/rd was used as the nonwoven fabric, and needling was performed at a density of 30 pieces/cI11.Then, the nonwoven fabric was impregnated with an acrylic resin liquid, and then nipped with a heating roller, and the dried filter medium was Configured.

Comparative Example 3 A product manufactured by another company was obtained by applying an acrylic resin liquid to a polyester spunbond nonwoven fabric with a date of 270 g/rrf as a nonwoven fabric, and then thermally pressing the fabric with a patterned roll to partially form a film from the nonwoven fabric.

Comparative Example 4 After passing an aqueous solution of cornstarch glue through a pulp paper with a pore diameter of 30 to 60 μm and a B attachment of 150 g/rrf.

Thickness: 0.0mm thick coated with epoxy resin and dried by heating. A 5 mm filter paper made by another company was obtained.

The following results were obtained regarding the physical properties of each nonwoven fabric in Example 1 and Comparative Examples 1.3.

Table 1 Method of measuring physical properties - The basis weight was based on JIS L-1085-5,2.

Thickness is I, 65ctj by dial sinkness gauge
The measurement was performed by applying a load of 50 g to the sample.

Tensile strength and elongation were determined by JIS L-1085-5°2, and tear strength was determined by J'IS L-1085-5,5C method.

For dry heat shrinkage, mark a 25cm x 25cm sample accurately in three places each vertically and horizontally, and heat it to 180cm in a constant temperature dryer.
After being left at ℃ for 3 minutes, the sample was removed and cooled to room temperature. Next, the change in the length of the marked pieces before and after drying was measured.

The stress at 5% and 3% elongation of the sample was based on JISL-1096.

Furthermore, the following results were obtained regarding the physical properties of the nonwoven fabric in Comparative Example 4.

Table 2 In the above measurement method, the basis weight and thickness are determined according to JISP-81.
, '88, bursting strength was determined according to JIS P-8112 (Shushin method), and tensile strength was determined according to 115P-8113.

From the above measurement results, even when a porous resin layer having water permeability was formed on one side of the nonwoven fabric according to Example 1, no deterioration in physical properties was observed.

In addition, the results of measurements regarding pore size and ventilation resistance are as follows.

Table 3 In the above measurement method, the pore size was measured using Toyo Roshi Bub
BLE tester, ventilation resistance is No. 869 manufactured by Toyo Seisakusho.
Using an airflow resistance tester.

The above measurement results revealed that although the filter medium of Example 1 had a smaller pore size than that of Comparative Example 1, its ventilation resistance was significantly higher.

Comparative measurements were also made regarding filtration performance. The measurement results are shown in the table below.

Table 4 Filtration performance measurement method JIS specified in JIS Z8901 as test powder
Using 8 types (standard powder of Japan Powder Industry Technology Association), the test liquid in the water tank is filtered through a filter medium having a filtration area of 0.217rrf in the test filter at an initial flow rate of 17Q/min. . 1 g of test powder is added to the liquid to be tested every 3 minutes up to 10 g, and after that, 3 g of test powder is added every 3 minutes after reaching 10 g. Measure the turbidity of the filtrate and the test liquid before adding the test powder using a turbidity meter, and when the turbidities of the same turbidity match, measure the total amount of the test powder film and use it as the clearing point.

In addition, the initial flow rate of 17Q/min was halved to 8.5Q/min.
The total amount of test powder input when it reaches m1n is measured and taken as the life.

The faster the water is clarified, the smaller the fining point and the better the filtration accuracy. Also, the longer the life, the higher the product value.

As is clear from this result, Example 1 is different from Comparative Examples 1 to 4.
It clears faster than Comparative Examples 3 and 4, and has a longer life than Comparative Examples 3 and 4.

[Effects of the Invention] Since the present invention is constructed as described above, processing debris in the processing fluid is sufficiently captured on the open foam layer with small pore diameters.
Gradually a cake forms and deposits on top of the open foam layer,
As a result, large processing wastes are captured by the cake, small processing wastes are captured by the continuous foam layer, and the filtration action progresses suitably. On the other hand, fine particles of processing debris are trapped in the pores of the foam and cause clogging, but as time passes, easily water-soluble glue materials such as carboxymethyl cellulose in the open foam dissolve and become spongy, creating new filtration pores. is formed, processing debris in the processing liquid is captured by the newly formed filter holes, and the filtering action proceeds without clogging, thereby extending the life of the filter medium. On the other hand, the nonwoven fabric layer of the main body layer has a reinforcing effect that can withstand the thickness of the filter medium due to the formation of a cake, and the cake can be peeled off properly, and it has moldability through needling and resin processing, so it does not lose its shape. Never. The spunbond mesh layer ensures mechanical strength and is tough.

As described above, the filter medium of the present invention has improved filtration efficiency of processing waste, has a fast fining point, has good filtration accuracy, has a long life span, and has increased commercial value. Furthermore, since the surface of the open foam is treated with resin, it has excellent cake removability and does not cause clogging due to cake when reused.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a filter medium showing an embodiment of the present invention, FIG. 2 is a schematic enlarged cross-sectional view of the same, and FIG. 3 is a perspective view of a filter body containing a filter medium showing an embodiment of the present invention. FIG. 4 is a partially sectional side view of the same. Continuous foam layer 2: Foam 3: Easily water-soluble adhesive 4: Nonwoven fabric layer 5: Filter medium'
6: Container 7: Frame
8: Hole 9 Nijilinda

Claims (6)

[Claims] (1) A filter medium having a porous layer, characterized in that a porous resin layer having water permeability is formed on one side of a nonwoven fabric. (2) A porous resin layer having a water permeability of 0.5 to 80% of the weight of the nonwoven fabric is formed on one side of the nonwoven fabric having a basis weight of 10 to 1000 g/m^2. A filter medium with a porous layer. (3) Claim (1) characterized in that the porous resin layer is an open foam formed by mechanically foaming or chemically foaming a resin.
Or a filter medium having a porous layer according to (2). (4) The resin forming the porous resin layer is a thermoplastic resin or a thermosetting resin, and an easily water-soluble glue material is added to the resin. ) or (3
) A filter medium having a porous layer as described above. (5) Claim (4) characterized in that the easily water-soluble adhesive material is polyvinyl alcohol, carboxymethyl cellulose, sodium alginate, starch, or equivalent substances thereof.
) A filter medium having a porous layer as described above. (6) Easily water-soluble glue is 0.05% of the solid content of the resin.
The filter medium having a porous layer according to claim 4 or 5, wherein the porous layer is added in an amount of 10% by weight.