JPS60187312A - Filter for dust collector and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a filter maintaining air permeability sufficiently by bonding porous polytetrafluoroethylene sheet by means of heat fusion of pills to one side of fibrous sheet base material having many pieces of pills which are made to low m.p. CONSTITUTION:One side of fibrous sheet-shaped base material 1 is singed with flame 2 to make many pieces of pills 3 of fiber. On one hand, porous PTFE sheet 4 is heated at m.p. or less of said base material 1 and also at m.p. or more of said pills 3 and press-fixed on pill-making surface of said base material 1 under pressure by a roller 5 or the like. The base material 1 and sheet 4 are heat-fused with only fine pills and excellent air permeability can be maintained. The sheet 4 has 5-200mu thickness, 0.01-50mu pore diameter and 40-95% porosity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a filter for a dust collector and a method for manufacturing the same.

Polytetrafluoroethylene (hereinafter referred to as PTFE)
In a porous sheet, it is easy to reduce the pore diameter, and the phenomenon of blowing through the filter (the phenomenon in which dust passes through the filter without being collected) can be easily prevented.

For this reason, a filter for dust collectors has been proposed in which a PTFE porous sheet is laminated with a fibrous sheet-like base material as a reinforcing material. In this case, it is necessary to ensure air permeability at the adhesion interface between the porous PTFE sheet and the fibrous sheet-like base material, and conventionally, partial adhesion in the form of dots, meshes, or stripes has been used. However, in these partial adhesion, for example, in the case of point adhesion,
The planar dimension of one point is significantly larger than the pore diameter of the porous PTFE sheet, and many of the pores in the porous sheet are blocked, resulting in poor air permeability retention and increased pressure loss as a filter. is remarkable.

In view of these points, the filter for a dust collector according to the first invention of the present application has a structure that can sufficiently maintain the air permeability of the porous PTFE sheet, and is made of a fibrous material having a large number of fluffs with a low melting point on one side. It is characterized in that a polytetrafluoroethylene porous sheet is adhered to one side of a sheet-like base material by heat-melting fluff.

The method for manufacturing a filter for a dust collector according to the second invention of the present application includes:
The filter according to the first aspect of the invention can be easily produced, and has a structure in which one side of a fibrous sheet-like base material is fluffed to form a large number of fiber balls, and a polytetrafluoroethylene porous sheet is coated on the one side. This method is characterized by bonding by heating and pressing.

Furthermore, in the method for manufacturing a filter for a dust collector according to the third invention of the present application, in order to make the filter surface uneven in order to improve the releasability of dust during backwashing, This method is characterized by heating to a temperature higher than the heat shrinkage temperature of the fibers of the shaped base material.

The present invention will be explained below with reference to the drawings.

In order to manufacture the filter according to the present invention, as shown in FIG. A large number of fiber balls 3, . . . are formed into tubes by fluffing one side of the .-shaped base material 1 using a frame 2. This fibrous sheet-like base material has breathability,
For example, felt, woven fabric, or non-woven fabric made of plastics such as polyester, polyamide, polypropylene, polyethylene, and fluororesin can be used. The temperature and time of the fluffing flame are set so that the size of the fluff is 0.
．． 2-0.8 dragon diameter, distribution density of hairballs 20-45 pieces/
It is preferable to set it to 1 nch. When the fibers become fluffed due to this fluffing, the crystal ratio of the fibers decreases, and the fluffed portion has a lower melting point than the remaining fiber portion. Furthermore, in fluffing, the fluffed fibers simply melt and become ball-shaped, so the air permeability of the fibrous sheet-like base material is hardly affected. In order to increase the distribution density of fluff, the fibrous sheet-like base material may be significantly fluffed by two-fold/chip processing, etc., and then fluffing may be performed.

On the other hand, the PTFE porous sheet 4 is heated to a temperature below the melting point of the fibrous sheet-like base material 1 and above the melting point of the fluff, and is heated to a temperature above the melting point of the fibrous sheet-like base material 1 by applying pressure using a roller 5 or the like. Press onto the pilling surface of the material. As shown by A in FIG. It is only heat-sealed by ... and can maintain excellent air permeability.

The above-mentioned porous PTFE sheet can be made porous by stretching or foaming, and the sheet thickness is usually about 5 to 2.
00μ, pore size 0.01-50μ, porosity 40-95
%.

The above-mentioned fibrous sheet-like base material has heat-shrinkability for the drawing process of the fibers, and if the product A obtained as described above is heated above its heat-shrinkage temperature in a non-tensioned state, the second As shown in the figure, the fibrous sheet-like base material 1 can be provided with irregularities, and the backwash releasability of surface dust can be improved. Further, it is clear from the experimental results described below that the heat shrinkage treatment can improve the air permeability by 10 to 20%.

Next, examples of the present invention will be described in comparison with comparative examples.

Examples 1 and 2 One side of polyester felt (fabric weight: 320 y/m") was fluffed with a propane gas flame to form an average of 28 fluff balls with a diameter of about 0.5 in 1-inch foil. Next,
PTFE porous sheet (thickness: 40μ, average pore size: 3.
5μ, porosity = 85%, air permeability: 5. OCCA-se
c (according to JIS L/096.6, 27./A method)) was pressure-bonded at a temperature of 190°C and a pressure of 1 to 9μ for 30 seconds to obtain the filter of Example 1 (in addition,
If not fluffed, it was not glued).

This filter was heated to 120℃ under no tension for 5 minutes.
The filter of Example 2 was obtained by heating for a minute. In this filter, some fine wrinkles occurred on the polyester felt surface.

-6 = Examples 3 to 5 The filter obtained in Example 1 was further heated under no tension for 5 minutes at 440°C, 150°C, and 200°C, respectively.
heated with. These filters had significant unevenness on their surfaces.

Comparative Example Unlike Example 1, instead of forming a pill by burning, a hot melt powder adhesive (melting point 135°C, softening point 110°C) was used.
) was processed and fixed on one side of polyester felt at 28 point dots per inch, and a PTFE sheet was adhered to the same side by heat and pressure in the same manner as in Example 1.

The air permeability, air permeability retention, interfacial adhesion, dust releasability, and pressure loss were measured for each of these Example products and Comparative Example products, and the results were as shown in Table 1.

The measurement procedures for each characteristic are as follows.

<Air permeability> According to JIS L 1096.6.27.1A method.

<Air Permeability Retention Rate> Calculate the air permeability of each filter/initial air permeability of the PTFE porous sheet.

<Interfacial adhesion> Each filter was fixed with a metal flange with a diameter of 100 mm, and a 6.0 kg sample was attached to the opposite side of the PTFE porous sheet.
/crI pulse air pressure (pressurize for 10 seconds, stop for 1 second) at 5
Observe the surface condition after adding 0 times.

<Dust releasability and pressure loss> The filtration area of each filter is 1 m+, and the particle size is 0.5 to 1.
Dust collection was carried out continuously for 100 hrs by blowing air containing 0μ wheat flour at a rate of 18517 m'' at a flow rate of 1 m'/sin to the PTFE porous sheet surface side of each filter, and further, at pulse intervals of 1 time. minutes, pulse pressure e,
The mold releasability of the dust after use is measured by adding 0 kg/i. △ indicates that dust is attached to some parts, ○
◎ indicates that a slight dust adhesion phenomenon is observed, and ◎ indicates that the dust has been completely released from the mold. Pressure loss is measured after applying the same pulse pressure and using it.

As is clear from Table 1, according to the present invention, PTFE
A filter made by laminating a porous sheet and a fibrous sheet-like base material can improve air permeability retention, improve dust release properties, and reduce pressure loss even when used for long periods of time. Energy saving effect can be achieved.

Table 1

[Brief explanation of the drawing]

9- Fig. 1 is an explanatory diagram showing an example of the method for manufacturing a filter for a dust collector according to the second invention of the present application, and Fig. 2 is an explanatory diagram showing an example of the filter for a dust collector obtained according to the third invention of the application. In the figure, l is a fibrous sheet-like base material, 3. ... is a pill, and 4 is a PTFE porous sheet. Agent Patent Attorney Minoru Shimizu 10-

Claims (3)

[Claims] (1) A film for a dust collector, characterized in that a polytetrafluoroethylene porous sheet is adhered to one side of a fibrous sheet-like base material having a large number of fluffs with a low melting point on one side by thermally melting the fluffs. Ta-. (2) A dust collector characterized in that one side of a fibrous sheet-like base material is fluffed to form a large number of fiber balls, and a porous polytetrafluoroethylene sheet is bonded to the one side by heating and pressing. Method of manufacturing filters for (3) One side of the fibrous sheet-like base material is fluffed to form a large number of fiber fluffs, a polytetrafluoroethylene porous sheet is heated and pressed on the same side, and then the fibrous sheet-like base material is heated and pressurized. A method for producing a filter for a dust collector, which comprises heating a material to a temperature higher than the heat contraction temperature of its fibers.