JPS63200812A - Filter medium for forming - Google Patents

Abstract

PURPOSE:To obtain the filter medium of no deterioration of preformance caused by the three dimentional forming by adhering fibrous sheet type substance with permeable thermoplastic sheet type substance in 1-50% rate of projection area. CONSTITUTION:The filter medium for forming consists of fibrous sheet type substance 1 forming ribs, thermoplastic sheet type substance 2 capable of forming three-dimensionally, and partial adhering parts 3. The fibrous sheet type substance 1 of 1-5mum diameter of single fiber, of 5-50% filling-up rate of fiber, and of >=70% breaking elongation at 120 deg.C is used, and, as for the thermoplastic sheet 2, the permeable one is used. And the fibrous sheet type substance 1 and the thermoplastic sheet 2 are adhered in 1-50% rate of projection area. Consequently, though the ribs are disappeared by the elongation when the three-dimensional forming is carried out, the structural sliding does not occur in the fibrous sheet type substance, so that the fibrous sheet type substance is free from the deformation caused by elongation, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a moldable filter material used as a filter requiring three-dimensional moldability.

<Conventional technology> In recent years, masks and vacuum cleaners have become widely used due to the rise in hygiene philosophy. However, the filters used in masks and vacuum cleaners have to be replaced frequently, making it difficult to manufacture them. There is a strong demand for compact and inexpensive products. One means to meet this demand is to manufacture these filters by an integral molding method, and to make this possible a filter material that can be three-dimensionally molded is required.

Conventionally, filter materials include paper, woven fabric, and non-woven sheet.

However, filter materials made of paper or woven fabric cannot be used as filter materials for three-dimensional molding because they cause cracks and tears when molded in three-dimensional form.

Furthermore, among filter materials made of non-woven sheets, short fiber non-woven sheets, needle-punched non-woven sheets, etc. are capable of three-dimensional molding to some extent, but the mechanism for this is due to misalignment of short fibers or one of the constituent fibers. Three-dimensional molding is performed by cutting the parts and making them into short fibers to increase the degree of freedom. For this reason, large deformation molding is not possible, uniform three-dimensional molding is difficult, and unevenness occurs, resulting in poor filter performance in misaligned areas, poor dust collection, poor shape retention, etc. There is. Therefore, resin processing is performed to improve the shape retention of the molded part. In addition, filter materials made of nonwoven sheets that use undrawn yarns with high breaking elongation as constituent fibers of long fiber nonwoven sheets can be formed into three-dimensional molding, but the mechanism is that the deformation stress occurs during three-dimensional molding. It is absorbed by the elongation of the fibers. For this reason, although the poor shape retention can be improved to some extent, it has the same drawbacks as the above-mentioned filter material, such as poor dust collection.

<Problems to be Solved by the Invention> The present invention solves the problems of the prior art and provides a molded filter material with excellent dust collection properties that does not deteriorate filter performance due to three-dimensional molding. be.

Means for Solving Problems〉 The present invention has a single fiber diameter of 0.1 to 5 μm and a fiber filling rate of 5 to 5 μm.
This is a filter material for molding in which a 50% fibrous sheet material and a thermoplastic sheet material having air permeability and having a breaking elongation of 70% or more under heating at 120° C. are joined together for 1 to 50% of the projected area.

Examples of the fiber sheet material in the present invention include a nonwoven fabric made by short fiber papermaking, a melt-spun long fiber nonwoven fabric, a carded web needle-punched nonwoven fabric, a glass fiber sheet material, and a melt-blown web. It is not limited to this, and any fiber sheet-like material that can be used as a filter may be used. As a web,
The effect is remarkable when a melt-blown web made of fine denier fibers produced by one-way melt-blowing is used. The web weight is 4! Although not limited to, K is preferably 10 to 200 g/n'' in order to obtain excellent filter performance.The fibers constituting such a web may have a single fiber diameter in the range of 0.1 to 5 μm. In other words, if the groove is 0.1 μm without grooves, the strength of the single fibers will be low and the subsequent handling will be poor.If it exceeds 5 μm, excellent dust collection performance will not be obtained and this is not preferred.

Fiber filling rate α (%) expressed as (〆/#)×100 of the fiber sheet-like material [〆 is the apparent density of the fiber structure, and ρ is the true density of the fibers. ] must satisfy 5≦α≦50.

More preferably, the range is 10≦α≦30. In other words, if the fiber filling rate is less than 5%, the fiber gaps become large and the fiber sheet becomes coarse, so that the amount of fibers per unit area tends to be uneven. Not only that, but the dust collection performance is also poor. Furthermore, if the fiber filling rate exceeds 50%, the fiber gap becomes small, the fiber sheet becomes dense, the air permeability is impaired, and the pressure loss increases, making it impossible to obtain a filter material suitable for practical use.

In the present invention, the thermoplastic sheet material includes, for example, fibrous materials such as polyethylene, polypropylene, polyvinyl chloride, polyester, nylon 6, nylon 66° polyurethane, and manned films. Preferably, fibrous materials such as knitted, woven, and nonwoven fabrics made of undrawn yarn, and thermoplastic sheet-like materials obtained by heat-shrinking these materials, such as -axially and biaxially stretched manned films, are preferable. Furthermore, there is a combination of these fiber materials and films. Such thermoplastic sheet material is
Three-dimensional molding is possible in a wide temperature range of 90 to 200°C, and the elongation at break when heated at a typical three-dimensional molding temperature of 120°C is 7.
0% or more, and at least has better air permeability than fiber sheet materials (air permeability measured by JIS L-1096 Frazier method: 1 to 400 ce/ctr?/w:
]. Preferably, the elongation at break under heating at 120°C is 100% or more. If the elongation at break under heating at 120° C. is less than 70%, sufficient three-dimensional moldability cannot be obtained, and when molding with deep unevenness is performed, uneven thickness, tearing, etc. occur, which is not preferable.

The projected area in the present invention is the (
S, /(S++St) ) X Projected area A (%) expressed as 100 [Sl is the area of the bonded portion, St is the area of the non-bonded portion. ], 1≦A≦50, preferably 5≦A
It is necessary that the range is ≦30. Projected area is 1%
If it is less than this, the bonding between the fiber sheet and the thermoplastic sheet will be poor and delamination will occur during three-dimensional molding, which is not preferable. When the projected area exceeds 50%, the effective filtration area of the molded product decreases when the composite sheet is three-dimensionally molded. As a result, pressure loss increases and the ν material becomes clogged with dust.
Its performance as a practical filter material is poor and is not preferred.

Furthermore, the term "joining" as used in the present invention includes partial thermocompression bonding using an embossing roll, partial fusion bonding using ultrasonic waves, high-frequency welding, etc., partial bonding using various adhesives, and the like.

Preferably, partial thermocompression bonding or partial fusion bonding is preferred. Furthermore, the bonded state is dotted (the shape of the bonded portion is circular, rectangular, or square).

It is not particularly limited to hexagonal shapes. ), lattice shape, linear shape, etc., preferably dotted joints and regularly arranged.

The present invention is characterized in that the above-mentioned specific fiber sheet-like material and a specific thermoplastic sheet-like material having air permeability and three-dimensional formability are composited by partial bonding, and the fiber sheet-like material is heated. The ridges are formed on a plastic sheet material. This makes it possible to form a fiber sheet-like product that does not have three-dimensional moldability into three-dimensional molding, and improves shape retention so that the molded product does not lose its shape.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Figures 1, 2-a, and 2-b are conceptual diagrams illustrating the molded filter material according to the present invention as a model, in which a fiber sheet forms ridges on a thermoplastic sheet. Indicates that That is, Figure 1 shows the original E! A perspective view of the filter material for molding according to A', FIG. 2-a is a cross-sectional view before molding, and FIG. 2-b is a cross-sectional view after molding. 3 is a thermoplastic sheet material having three-dimensional formability, and 3 is a partial joint.

In molded filter materials with such a structure,
During three-dimensional molding, the thermoplastic sheet-like material and the fiber sheet-like material constituting the filter material for molding are simultaneously stretched. At this time, since the fiber sheet-like material has ridges as described above, the ridges disappear when it is stretched, but since no tissue shift occurs within the fiber sheet-like material, the fiber sheet-like material Not subject to deformation such as stretching. Therefore, the fiber sheet material can be three-dimensionally molded while maintaining excellent dust collection properties. in this case,
The degree of disappearance of the ridges and the degree of stretching are not limited as long as they do not substantially change the performance.

Next, FIGS. 3-a and 3-b are model diagrams showing an example of a molding apparatus used for three-dimensional molding according to the present invention.

That is, Figure 3-a shows the molding device and the object to be molded before molding, and Figure 3-b shows the cross section of the molding device and the object to be molded during molding (the molded object). This is a schematic diagram of 4
5 is a frame for holding the molded object, 6 is a heating element which can be moved up and down, and 4' is a molded object. In this 5K, the shape of the three-dimensional molding of the present invention is determined by the shape of the heating body,
For example, any shape such as a cylindrical shape, a biconical truncated cone shape, a rectangular parallelepiped shape, a hemispherical shape, etc. is selected depending on the purpose.

The filter material for molding of the present invention may optionally contain a water permeable agent,
Processes include coloring with water repellents, antistatic agents, pigments, and dyes. Furthermore, activated carbon, an adsorbent, a water-absorbing polymer, etc. may be enclosed between the fiber sheet-like material and the thermoplastic sheet-like material depending on the purpose.

<Examples> The present invention will be specifically described below with reference to Examples and Comparative Examples.

The method for measuring the characteristic values used in the present invention is shown below.

Breaking strength under heating at 150°C; Universal tensile tester (Auto Graph manufactured by Takasugi Seisakusho)
DSS-2000 model), using a thermostat for tensile testing machine, gripping length 50cm in a tank with an ambient temperature of 120℃,
The evaluation is based on a load-elongation curve obtained by measuring at a tensile rate of 1001 minutes.

Three-dimensional moldability: Maximum area ratio of molded body: When molded using the molding equipment shown in Figures 3-a and 3-b under the conditions of a heating element temperature of 120°C and a molding time of 30 seconds, the molding It is expressed as the maximum area ratio (Ss/So) of the molded body, which is expressed as the ratio of the squeezed area (S-) before molding to the expanded total surface area squeezed after molding (S, ).

Three-dimensional formability: S, 4°2.
The shape of the molded product at 30 o'clock is evaluated using the following criteria.

<Judgment criteria> O: No tearing or destruction occurred.

×: Tearing and destruction occurred.

Dust collection property: Collection efficiency; JISK-8901 test duct 13 type B method 0.3μ
The evaluation was made by measuring the dust collection efficiency of m-average stearic acid aerosol.

Pressure drop: Evaluate by pressure drop measured under the same conditions as for collection efficiency measurement.

Example 1 Single fiber diameter 1.7 μm obtained by one method of Melt Pro
The basis weight is 20. l;+7m”, fiber filling rate 60
Weight based on % 30p/ff! ”, breathability 300c
Polyester long fiber nonwoven sheets of t:/cttr"Aac were overlapped and partially thermocompressed between an embossing roll having a convex portion on the upper part and a lower roll having a smooth surface.

When concave, the unit m product force of the convex part of the embossing roll ζ21ni
&, crimping area ratio is 12%, upper and lower roll temperature is 90℃
, partial thermocompression bonding was performed under a linear pressure of 20 kC and 97 cm to obtain a composite sheet. Next, the composite sheet was steamed at a temperature of 90°C.
, shrinkage processing under conditions of a residence time of 60 seconds.

50% in the latitudinal direction), dried, and a composite sheet having a projected area of 12% was bonded at points. Table 1 shows the performance of the composite sheet obtained.

Examples 2 and 3 A polypropylene fiber sheet with a fabric weight "zoo/rn" and a fiber filling rate of 17%, mainly composed of single fibers with a diameter of 5 μm, obtained by the MeltPro one-way method, and a biaxially stretched manned polyethylene film (in the warp and weft directions) 50% shrinkage) were superimposed and thermally bonded in a lattice and linear shape with a fused area ratio of 15% by ultrasonic bonding to obtain a composite sheet.Hereafter, the same shrinking process as in Example 1 was performed. , a composite sheet of Example 2.3 was prepared.

Table IIlc shows the performance of the obtained composite sheet.

Comparative Example 1 The same operation as in Example 2 was carried out to produce a composite sheet before shrinkage processing, except that in Example 2, a woolly processed yarn of 50 denier 24 filaments of polyester fiber with a water production shrinkage rate of 1% was used. It was created. Table I shows the performance of the composite sheet.
Show K.

Table-1 *1: Breaking speed of thermoplastic sheet in warp and weft directions *2
: as / 1% = 3.0 As shown in Table 1, the dust collection property of the finished body after molding is as / 1% = 3.0
It can be seen that compared to K, it is superior in three-dimensional formability and dust collection after the bottom plate.

Comparative Examples 2 and 3 In Example IVc, basis weight 509/WE-fiber filling rate 3% (Comparative Example 2) 55%, mainly composed of single fibers with a diameter of 20 μm
(Comparative Example 3) A composite sheet was prepared in the same manner as in Example 1, except that a polyester fiber sheet material processed to have K was used.

In Comparative Example 2, the composite sheet had a low collection efficiency of 8% and had poor dust collection performance.

In Comparative Example 3, the pressure loss of the composite sheet was high (unfavorable as a practical filter material).

Comparative Examples 4 and 5 In Example 3, except that point heat fusion with a fusion area of 0.5% (Comparative Example 4) and lattice heat fusion with a fusion area of 55% (Comparative Example 5) were performed. A composite sheet was prepared by performing the same operation as in Example 3.

In Comparative Example 4, delamination occurred between the fiber sheet and the film during three-dimensional molding.

In Comparative Example 5, the composite sheet had a high pressure loss and was not preferred as a practical filter material.

<Effects of the Invention> The filter material for molding according to the present invention does not reduce the excellent dust collection properties of the fiber sheet (enables three-dimensional molding and improves the shape retention of the filter material after molding). be able to.

As a result, products in a wide range of fields can be used as filter materials, such as vacuum cleaners, masks, automobile air filters, and filters for extracting components of oil, black tea, coffee, green tea, and the like.

[Brief Description of the Drawings] Figures 1, 2-a, and 2-b are conceptual diagrams explaining the molded filter material of the present invention as a model, and Figure 1 is an example of a composite sheet. Fig. 2-a is a sectional view showing an example of the basic structure of a composite sheet, and Fig. 2-b is a sectional view showing an example of the composite sheet after three-dimensional molding. Figure 3-a and Figure 3-b are model explanations of the bottom plate device and the state of the molded object before and after molding, and Figure 3-a
The figure is a cross-sectional view schematically showing the state before construction, and Figure 3-b is
FIG. 3 is a cross-sectional view schematically showing the product after molding. DESCRIPTION OF SYMBOLS 1... Fiber sheet-like material with ridges formed therein, 2... Thermoplastic sheet-like material, 3... Joint portion, 4... To-be-molded object, 4
'... Molded object, 5... Frame for holding the molded object, 6°
°°Heating element that can be moved up and down. Patent issued Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] A fiber sheet with a single fiber diameter of 0.1 to 5 μm and a fiber filling rate of 5 to 50%, and a thermoplastic sheet with air permeability and a breaking elongation of 70% or more when heated at 120°C have a projected area of Filter material for molding with 1 to 50% bonded