JPH03249251A - Production of nonwoven fabric of porous glass yarn - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a porous glass fiber nonwoven fabric used as a filter, adsorbent, etc.

(Conventional technology) Porous glass fiber is a glass fiber with countless three-dimensional pores, and because of its high silicic acid content, it has excellent chemical resistance and heat resistance, and because it is porous, it has excellent adsorption properties for gas molecules. Because of its excellent properties, it is increasingly being used as an adsorbent for various gases and as a deodorizing agent.

In order to produce the porous glass fiber, glass having a phase-separated borosilicate composition is melted, formed into fibers by a known method, and then heat-treated to separate an acid-soluble phase and a poorly soluble SiO □
The acid-soluble phase is then eluted by acid treatment. As a result, the 5iOz phase hardly dissolves in acid and remains in its original shape, forming a three-dimensional network structure.
A porous glass fiber containing 5iOz as a main component is obtained.

(Problems to be Solved by the Invention) However, since porous glass fibers are used while being stored in an air-permeable container or the like in their fibrous state, they are inconvenient to handle. For this reason, it is desirable to use porous glass fibers as nonwoven fabrics. If it is a non-woven fabric,
It can be used as is as an air filter, etc. There are various methods for producing nonwoven fabrics, but the wet method is simple. That is, short fibers are dispersed in an aqueous solution (dispersion medium) containing a water-soluble binder, and this is poured onto a wire mesh, dehydrated, and dried.

However, when attempting to manufacture a nonwoven fabric using porous glass fibers, the water-soluble binder permeates into the pores, which impairs adsorption. In addition, if a nonwoven fabric is manufactured using split-phase glass fiber before acid treatment, and then acid treatment is performed to make it biporous, the water-soluble binder will dissolve in the acid solution during the acid treatment process, and the fibers will become diporous. is redispersed, making it impossible to obtain the desired nonwoven fabric.

The present invention was made in view of such problems, and an object of the present invention is to provide a method for producing a porous glass fiber nonwoven fabric that does not impair adsorption properties.

(Means for Solving the Problems) The manufacturing method of the present invention, which has been made to achieve the above object, consists of a glass fiber whose silica phase and an acid-soluble phase have been separated by heat treatment, and a heat-fusible synthetic fiber. are mixed and dispersed in a dispersion medium containing a water-soluble binder, the dispersion medium is removed and dried to obtain a phase-separated glass fiber nonwoven fabric, and the nonwoven fabric is heated to melt the synthetic fibers and partially bond the glass fibers together. After adhering to the nonwoven fabric, the phase split glass fiber nonwoven fabric is subjected to acid treatment to elute the acid-soluble phase, washed with water, and dried.

(Function) The water-soluble binder in the dispersion medium imparts a shape-retaining effect and strength to the phase-separated glass fiber nonwoven fabric, thereby facilitating subsequent handling.

When the formed phase split glass fiber nonwoven fabric is heated, some or all of the heat-fusible synthetic fibers in the nonwoven fabric melt, and the glass fibers are partially bonded to each other. As a result, the shape of the nonwoven fabric is maintained by the fusion of the water-soluble binder and the synthetic fibers.

Thereafter, the phase split glass fiber nonwoven fabric is subjected to acid treatment. At this time, the water-soluble binder dissolves in the acid solution and the shape retention effect disappears. However, since the glass fibers are kept in shape by fusing the synthetic fibers, the glass fibers will not be redispersed in the acid solution.

Moreover, since the synthetic fibers are only partially fused, the elution of the acid-soluble phase is not hindered, and the phase-separated glass fiber can be made porous. Note that since the amount of the water-soluble binder redissolved in the acid is small, there is no risk of clogging the pores.

(Example) In carrying out the present invention, first, a nonwoven fabric made of phase-separated glass fibers and synthetic fibers having thermal fusibility is manufactured by a wet method.

The phase-separated glass fiber is made of 5i, which is hardly soluble in acids, by heat treatment.
Melting glass that separates into an Oz compound phase and an acid-soluble phase,
After spinning and forming into fibers, this is cut into lengths of about 4 to 15 m and subjected to phase separation heat treatment by holding at 550 to 800 "C" for the required time.
azOB2O25iOz-based borosilicate glass, CaO
-/V, 0. -B20. -5 inch, type borosilicate glass, etc. can be used. An example of the composition (wt%) is shown below.

CaO: 8-25%, /Vz03: 5-15%
B! 0. : 8-30%, 5in2: 45-7
0% The heat-fusible synthetic fiber is polyethylene (P
E) Short fibers of about 4 to 15 mm made of heat-softening resins such as polypropylene (PP), polyethylene terephthalate (PET), and polyamide are used, and financial type (made of one type of component) ,
Any semi-melting type (formed by a composite of a high melting point component and a low melting point component) can be used.

The semi-melting type has a low melting point component (low melting point PP with a low degree of polymerization, low melting point PE, copolymerized PET, copolymerized polyamide, etc.) arranged in parallel with a high melting point component (side, pie, side). There are two types: a sheath-core type) and a sheath-core type that is arranged concentrically on the outside. Either type can be used. The blending amount of heat-fusible synthetic fiber is not particularly limited, but for financial type, it is 3% compared to the total amount of glass fiber.
-10%, and about 5-30% for semi-melting type.

The split phase glass fiber and heat-fusible synthetic fiber include hydroxyethyl cellulose and polyvinyl alcohol (PVA).
It is stirred and dispersed in an aqueous solution (dispersion medium) containing a water-soluble binder such as.

The concentration of the binder is about 0.5 to 5 wt%. It is separated by a wire mesh for filtering and dried to form a nonwoven fabric.

Next, the phase split glass fiber nonwoven fabric is heated to melt the heat-fusible synthetic fibers and partially bond the glass fibers together. The heating temperature varies slightly depending on the type of synthetic resin, but is approximately 100 to 120°C. When using a semi-melting type synthetic fiber, it is heated at a temperature intermediate between the melting temperature of the low melting point component and the melting temperature of the high melting point component. A semi-melting type is preferable because it can be bonded in a dotted manner at the intersection with the glass fiber, and the acid-soluble phase can be rapidly eluted during the acid treatment described below.

The split-phase glass fiber nonwoven fabric partially fused with synthetic fibers is immersed in 0.2-6N hydrochloric acid, nitric acid or sulfuric acid,
The acid-soluble phase is eluted from the phase-separated glass fibers by heating at a temperature of 60-90°C. By such acid treatment, the phase-separated glass fiber becomes a porous glass fiber consisting of a three-dimensional skeleton mainly composed of SiO□ and pores. In the acid treatment, the water-soluble binder in the split-phase glass fiber nonwoven fabric during nonwoven fabric molding is redissolved in the acid solution, but it is not redispersed because it is partially fused by the synthetic fibers. After the acid treatment, the nonwoven fabric is washed with water and dried to obtain a porous glass fiber nonwoven fabric product.

Next, specific examples will be shown.

(1) Glass fiber with the following composition (wt%) (fiber diameter 1
(0μm, fiber length: 6) was held at 600”C for 12 hours to cause phase separation.

5iOz: 49%, NzOs: 9%B
,0. : 15%, CaO: 17% Others:
10% (2) (1) split-phase glass fiber and sheath-core type semi-fusible synthetic fiber (2.5 denier, 5 fiber lengths)
and 1% PVA (degree of polymerization n =
1,500 to 1,800) was stirred and dispersed in an aqueous solution, poured evenly onto a wire mesh to form a nonwoven fabric, and dried.

Note that the low melting point component in the outer periphery of the semi-melting type synthetic fiber is copolymerized PET, and the high melting point component in the center is PET.

(3) The split-phase glass fiber nonwoven fabric formed in (2) was heated at 110° C. for 30 minutes to melt the low melting point component of the synthetic fibers and bond the fibers together at points.

(4) After that, it was immersed in 10.5N hydrochloric acid at 80°C for 1 hour, then washed with water and dried.

(5) Using the obtained porous glass fiber nonwoven fabric, the pore characteristics of the porous glass fiber were investigated by the N2 gas adsorption method. As a result, the BET surface area was 29 ft/g, and the pore volume was 0.
2d/g, which was slightly inferior to that of non-woven porous glass fibers, but was a value that caused no practical problems in terms of adsorption.

(Effects of the Invention) As explained above, according to the method for producing a porous glass fiber nonwoven fabric of the present invention, a nonwoven fabric is formed using a split-phase glass fiber and a thermally bonded synthetic fiber through a water-soluble binder. Since the synthetic fibers are melted and the glass fibers are partially bonded together and then treated with an acid, there is no risk that the nonwoven fabric will redisperse and fall apart even if the water-soluble binder dissolves during the acid treatment. Moreover, there is no fear that the pores formed by the elution of the acid-soluble phase will be clogged, and a nonwoven fabric with good adsorption properties can be easily produced.

Claims (1)

[Claims] (1) Glass fibers whose silica phase and acid-soluble phase have been separated by heat treatment and heat-fusible synthetic fibers are mixed and dispersed in a dispersion medium containing a water-soluble binder, and the dispersion medium is removed and dried. After heating the nonwoven fabric and melting the synthetic fibers to partially adhere the glass fibers to each other, the phase splitting glass fiber nonwoven fabric is subjected to acid treatment to remove the acid-soluble phase. A method for producing a porous glass fiber nonwoven fabric, which comprises elution, washing with water, and drying.