JPS6182819A - Filter medium - Google Patents

Abstract

PURPOSE:To obtain the title filter medium wherein fuzz is scarcely generated by using a web consisting of a parallel conjugate fiber on the inflow side and a web consisting of a core-sheath conjugate fiber on the outflow side. CONSTITUTION:A web contg. >=50% core-sheath fiber is formed on a reticular conveyor by a card or an air lay method and web contg. >=30% parallel fiber is superposed thereon. The low m.p. component in the conjugate fiber is melted by blowing hot air on the web from above and below the web to bond both fibers. At this time, the surface of the web in contact with the conveyor is sufficiently bonded to form a dense surface and a filter medium having a density gradient can be obtained. A fiber having higher m.p. than the low m.p. component is preferably mixed into the conjugate fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) This invention relates to a filter material suitable for P/P of fluids such as gases or liquids.

(Prior Art) Conventionally, one of the methods for making filter materials is a method using parallel type composite fibers containing a low melting point component and a high melting point component, which is well known from Japanese Patent Publication No. 5 (1973) (No.-18787, etc.). It is also known to use filter materials with different densities as one of the methods to increase the collection efficiency and extend the life of the filter material.

Therefore, by fusing the constituent fibers with adhesive composite fibers, a so-called density gradient type filter material having a difference in density between the front and back surfaces can be obtained. However, with conventional methods, it is difficult to obtain a filter material that is uniform and has a sufficiently large density difference, and it is also difficult to reduce the occurrence of fuzz on dense surfaces. If the density difference is small as in the past, the life of the filter material will not be long, and if more fuzz is generated on the dense surface from which the liquid flows out, the fuzz will fly off during use and the filter material itself will become dusty. This is not desirable because it becomes a source of generation.

(Problems to be Solved by the Invention) In order to overcome the conventional drawbacks, the present invention extends the life of the filter material by providing a sufficient density difference, and further densifies the dense surface to reduce fuzz on the fluid outflow side. To some extent, it is intended to prevent its scattering.

Means for Solving Problem C) The present invention provides a filter material formed by heat-sealing a web containing composite fibers, in which the fluid inflow side of the filter is composed of a web containing parallel composite fibers, and the fluid outflow side is composed of a web containing parallel composite fibers. A filter material characterized in that it is composed of a web containing 50% or more of core-sheath composite fibers.

The composite fiber in the present invention is composed of a low melting point component and a high melting point component, and the low melting point component has the effect of layering the fibers together through heat treatment, and the ratio of the low melting point component and the high melting point component is within an appropriate range. Can be designed.

Typical combinations of low melting point components and high melting point components are polyethylene-polypropylene, nylon 6-nylon 66, etc., but various other polyolefin-based, polyamide-based, and polyester-based materials can also be used. .

(Function) The present invention has a major feature in that the fluid inflow side and fluid outflow side are constructed using webs each containing parallel type conjugate fibers and core-sheath type conjugate fibers. Conventionally, bonding was done using parallel composite fibers, so if the low melting point components intersect or are adjacent to each other, the bond is sufficient and there is almost no fuzz. There was a problem in that the adhesive was not adhered at all and fluffing was noticeable.

In the present invention, a core-sheath composite fiber whose entire surface is coated with a low melting point component is used as the adhesive fiber for the outflow side web, so the low melting point component is not necessarily present at the intersection or adjacent points of the fibers. Since it is bonded, there is almost no fuzz. Furthermore, the brain has a dense structure in which the number of crossing or adjacent connection points is far greater than 0 in the conventional brain.

On the other hand, since the web on the inflow side uses conventional parallel fibers as adhesive fibers, the number of bonding points between the fibers is smaller than on the outflow side, and the density is also smaller, as in the past.

If at least the inflow side web and the outflow side web are overlapped and heat-treated in this way, the filter material with a density gradient of the present invention can be obtained, but the core-sheath type composite fiber used on the outflow side has a content of at least 50% or more. Required, preferably 75-10
It is 0%.

An example of the method for manufacturing the filter material of the present invention will be explained below.

First, a web containing at least 50% of core-sheath type fibers is formed on a net-like conveyor by a gold card method, an air-laying method, etc., and a web containing preferably 30% or more of parallel type fibers is layered on top of this. By blowing hot air from the upper and lower parts, the low melting point components of the composite fibers are melted and the fiber 1 south is layered. At this time, by sufficiently adhering the web surface in contact with the conveyor, a dense surface is formed and a filter material with a density gradient can be obtained.

Note that general synthetic fibers may be used for the fibers other than the core-sheath type and the parallel type fibers, but if fibers with a melting point lower than the low melting point component are used, the thickness of the resulting filter material may collapse or the initial It is better to mix in a material with a higher melting point, as this is undesirable as it will cause pressure loss and other problems.

° Also, a, which has properties such as flame retardancy, heat resistance, and adsorption properties,
It is more preferable to mix fibers, as this will result in a filter material with improved various percentages. 4 (Examples and Comparative Examples) Example 1 High melting point component is polypropylene, low melting point component is low pressure polyethylene, the ratio is 1=1, thickness 3 denier,
It is made of 100% parallel composite fibers with a length of 64 mm.
A core-sheath composite fiber with a thickness of 8 denier and a length of 64 ff, with a web of 50 fβ as the upper layer, a high melting point core component of polypropylene, and a low melting point sheath component of low pressure polyethylene in a ratio of 1:1. Weight 1501.consisting of lOO%. A web with a weight of 300 fβ, which was laminated with a web of Ad as the lower layer, was placed on a net-like conveyor and heat-treated at 140° C. for 5 minutes in a dryer blowing hot air from above and below, to obtain a filter material with a thickness of 2+11. This filter material had a large density gradient, and the surface of the lower layer was dense and smooth with no fluff. This filter material with the lower layer on the gas outflow side was preferred because of its high dust collection efficiency and large amount of dust supply.

Comparative Example 1 Using only the parallel composite fibers used in Example 1, the weight aoo
A web of yβ was made and heat treated under the same conditions as in Example 1 to obtain a filter material with a thickness of 251r11. Although this filter material had a gentle density gradient, a lot of fuzz was observed on the surface of the lower layer, which was not desirable.

Comparative Example 2 Using only the core/sheath type composite fiber used in Example 1, the weight was 3.
A web of 00yβ was made and heat-treated under the same conditions as Example 1 to obtain a filter material with a thickness of 15xm. This filter material was dense with little density gradient, and the surface of the lower layer was completely free of fuzz.

Example 2 A mixed web of weight i1i 150 f7fn'' consisting of the same parallel composite wire a7o% as in Example 1 and 30% polyester fibers with a thickness of 3 denier and a length of 642 r11 was used as the upper layer, and the same core as in the example material was used. 55% sheath type composite fiber and Example 1
Weight 1501A consisting of 45% of the same parallel type composite fiber as
A web with a weight of 300yβ laminated with the mixed web of d as the lower layer was heat-treated under the same conditions as in Example 1 to a thickness of 24jr.
I got JL's filter material. This filter material had a large density gradient, and although a slight amount of fuzz was generated on the surface of the lower layer, no particular problem occurred in practical use.

The physical property data of the filter materials of these Examples and Comparative Examples are shown in the table.

Table (Effects of the Invention) As described above, the filter material of the present invention has a large density gradient, is dense on the fluid outflow side, does not generate fuzz, has high strength and excellent physical properties, and can be used as a filter material. It has an extremely long lifespan.

Claims (1)

[Claims] 1. In a filter material formed by heat-sealing a web containing composite fibers, the fluid inlet side of the filter is composed of a web containing parallel type composite fibers, and the fluid outlet side is composed of a web containing parallel type composite fibers, and the fluid outlet side is composed of a web containing parallel composite fibers.
A filter material comprising a web containing 0% or more of core-sheath composite fibers.