JPH03143513A - Polyolefinic filter medium - Google Patents

Abstract

PURPOSE:To obtain the polyolefinic filter medium from which collected solid is easily released by forming at least a part, preferably >= about 50%, of the surface of the filter medium (inlet side) with the fiber consisting of poly-4- methylpentene-1. CONSTITUTION:At least a part, preferably >= about 50%, of the surface of the filter medium into which a gas or fluid to be filtered is introduced is formed with the fiber of poly-4-methylpentene-1. Among the nonwoven fabrics, a fiber sheet consisting of the fiber with the whole or >= about 50% of the surface being poly-4-methylpentene-1 and the fiber having a thermoplastic resin component such as the polyamide, PP and various PE fibers having a m.p. >=10 deg.C lower than that of poly-4-methylpentene-1 is pressed and heated to obtain a remarkable effect. A filter medium resistant to chemicals and heat and from which cake is easily released is obtained by this method.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for separating solids dispersed in gas or liquid. It relates to filtration materials (filter media). That is, the present invention relates to liquid filtration media such as bag filters that collect solids dispersed in gas, vacuum filtration media that separate cake and mother liquor from solid liquids, filter presses, furnace leaf filtration media, and belt press filtration media. It can also be applied to filtration materials used in filtration materials, or other materials, such as materials for concrete formwork to extract excess water from concrete milk.

[Conventional technology, issues]

Traditionally, woven fabrics such as single-sided flannel were used as filtration materials for liquid filters, such as filter presses, and woven fabrics were used as a base to maintain strength, and synthetic fibers were planted on top of the woven fabrics by needle punching. A felt-like material is used.

However, if the purpose of using a liquid filter is to collect solids present in the liquid, the solids (cake) collected on the surface of the furnace material will adhere to the surface of the furnace material and the cake will separate from the furnace material. However, it has the disadvantage that the efficiency and efficiency of solid recovery are lowered.

In order to improve such drawbacks, for example, Japanese Patent Application Laid-open No.
As shown in Japanese Patent No. 135021, a fiber material having good cake releasability has been proposed, which is obtained by mixing composite fibers of polyethylene and polypropylene into a web and heat treating the mixture. But also by such a furnace material? At present, the cake removability from P44 is still insufficient.

Even in bag filters that separate powders from gases, various methods have been proposed for removing powders (solids) that have accumulated on furnace materials. The releasability of the powder is still not satisfactory.

Furthermore, it is a fact that there is no conventional furnace material that has sufficient removability, chemical resistance, and heat resistance.

[Means and actions for solving problems]

The inventor of the present invention has conducted intensive studies in order to easily separate the filtered solid from the furnace material, and as a result, has arrived at the present invention.

That is, at least a portion of the furnace material surface (inlet side) into which the gas or liquid to be filtered flows, preferably 50
It has been discovered that solids collected on the furnace material can be easily peeled off from the furnace material by composing the fiber with polymethylpentene component. Moreover, the material according to the present invention has both excellent chemical resistance and heat resistance, and the significance of the present invention is extremely large.

Here, polymethylpentene is 4-methylpentene-1
It is a type of polyolefin obtained by polymerizing, etc., and includes those in which less than 50% of the second component is copolymerized or blended. It also includes those to which matting agents, pigments, etc. are added.

In order to obtain the material of the present invention from polymethylpentene,
First, polymethylpentene is made into monofilament, multifilament or staple fiber by conventional melt spinning and drawing. The obtained fibers are made into woven fabrics such as plain weave, twill weave, lattice weave, single layer weave or layered weave, or needle felt (non-woven fabric) by needle punching, etc., and provided as furnace material. These woven and nonwoven fabrics may be subjected to post-processing such as calendering.

In addition, a nonwoven furnace material exhibiting the effects of the present invention can also be obtained from polymethylpentene by a spunbond method or a melt blown method. When using the melt-blown method, polymethylpentene, which has a relatively low degree of polymerization, is suitable, and a melt-blown non-woven fabric is layered on a base fabric made of polyolefin fibers, and the melt-blown non-woven fabric is calendered so that the surface on the side of the fabric is smooth. is preferred.

Furthermore, among nonwoven fabrics, the effects of the present invention are particularly noticeable in the following nonwoven fabrics. i.e. all or 50% of the fiber surface
At least 40% of the fibers are polymethylpentene (staple fibers), and at least part of the fiber surface contains a thermoplastic resin component with a melting point 10°C or more lower than that of polymethylpentene (staple fibers)
A nonwoven fabric with a smooth surface obtained by pressurizing and heating a fiber sheet (web) consisting of 60% or less is particularly suitable for obtaining the effects of the present invention.

Here, the fibers containing a thermoplastic resin component having a melting point 10°C or more lower than that of polymethylpentene include polyamide, polypropylene, various polyethylene fibers, etc., but composite fibers and mixed fibers of polypropylene and polyethylene are preferable. Furthermore, side-by-side (bimetallic) type, preferably sheath core type, composite fibers of polymethylpentene and polypropylene are the object of the present invention, but from the purpose of improving the peelability or heat resistance of the material, This is preferable.

〔Example〕

Example 1 Composite short fibers having a core of polymethylpentene (melting point: 240°C) and a sheath of polypropylene (melting point: 170°C) having a diameter of 3°5 and a length of 51 mm were obtained by melt spinning. At this time, the ratio of polymethylpentene to polypropylene is 50:50.

On the other hand, from 100% polymethylpentene, the same <3.5
Short fibers (staple fibers) with a denier and a fiber length of 51 were produced.

Next, the composite fiber 43 made of polymethylpentene and polypropylene! X and the above polymethylpentene fiber 5
7% cotton and carded it into a fiber web.
The webs were laminated by the crosslay method, and the fabric weight was 250.
g/rrf.

This web was layered on a woven fabric made of polymethylpentene spun yarn with two twists of No. 24 and having a basis weight of 110 g/rrf to give a total basis weight of 360 g/m. Next, from the fiber web side,
320 needle punches were performed per square centimeter.

The thus obtained laminate was heated with hot air at 150°C, and then immediately subjected to pressure treatment so that the fiber web side was in contact with the calender roll side whose surface temperature was 175°C. As a result, the fiber web side had a very smooth surface.

When the thus obtained laminate of woven fabric and non-woven fabric was used as a furnace material for a fully automatic filter press to filter 2.5% clean water sludge, the femininity of Cake 411 after opening was extremely good. Ta.

Example 2 A 60 count spun yarn made of polymethylpentene fiber was obtained,
2 depending on the density of 55 pieces per inch both vertically and horizontally
/3 Twill woven fabric was obtained.

When the obtained woven fabric was used as a dust collecting bag filter/furnace material for the exhaust gas of a coal-fired boiler, it was found that the temperature was 110°C despite the presence of sulfur compounds in the exhaust gas.
It also withstood regular use and had excellent dust removability.

〔Effect of the invention〕

As is clear from the above description, it is clear that according to the present invention, a resin material with excellent cake removability that also has chemical resistance and heat resistance can be obtained.

Claims (2)

[Claims] (1) A polyolefin filter medium, characterized in that at least a portion of the fluid inflow side surface is composed of fibers having a polymethylpentene component. (2), from fibers having a polymethylpentene component on at least part of the fiber surface and polymethylpentene components,
A polyolefin filter material having a smooth surface and excellent solid releasability obtained by pressurizing and heating a fiber sheet made of fibers containing a thermoplastic resin component having a melting point lower than ℃ or higher.