JPH07328355A - Dust filter and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a glass fiber dust filter having excellent water resistance, small pressure loss, and large collection efficiency. [Structure] A glass fiber dust-removing filter in which a glass fiber is surface-treated with an organosilane having a hydrolyzable group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass fiber dust filter having excellent water resistance and dust collecting performance and a method for producing the same.

[0002]

2. Description of the Related Art Dust filters have been widely used in air conditioning systems for realizing a clean room for keeping the dust concentration in the air extremely low in the electronics industry, medical field and the like. In this system, a prefilter mainly made of a polymer material having a low ventilation resistance for capturing dust having a large particle size and a HEPA filter mainly composed of glass fiber for capturing dust of submicron or less are used. A normal glass fiber HEPA filter is
A small amount of chopped strand glass fiber is mixed with an ultrafine glass fiber having a fiber diameter of 4 μm or less, and the glass fibers are bonded with an organic binder of 7% or less for imparting strength.

In order to reduce the pressure loss as a filter paper and improve the collection efficiency, a fluorine-containing resin such as polytetrafluoroethylene is used as a binder (Japanese Patent Laid-Open No. 62-90395), and a silicone resin such as polyresin is used in the binder. It is known to blend dimethylpolysiloxane (JP-A-2-41499).

However, these conventional glass fiber HEPA filters do not have sufficient water resistance, and there is a problem that their service life is shortened in a humid environment or in coastal areas where salt water is contained in the atmosphere. .

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional glass fiber dust filter, and is a glass having excellent water resistance, small pressure loss and large collection efficiency. The purpose is to provide a fiber dust filter.

[0006]

Means for Solving the Problems As a result of earnest research, the inventors of the present invention have shown that the surface of glass fibers constituting a glass fiber dust filter is treated with an organosilane having a hydrolyzable group to significantly improve water resistance. It was found that the dust collection performance of the filter is improved and the dust collection performance of the filter is also improved.

That is, the present invention is a glass fiber dust-removing filter in which glass fibers are surface-treated with an organosilane having a hydrolyzable group.

In the present invention, an organosilane having a hydrolyzable group is used. Here, the hydrolyzable group means an acetoxy group, an alkoxy group, a chlorine group and a fluorine group. As the organosilane having a hydrolyzable group, those used in conventional water-repellent or antifouling glass can be used. From the viewpoint of durability, the hydrolyzable group is
It forms a chemical bond at the interface with the base to improve durability. Specifically, acetoxy group, alkoxy group,
Organosilanes, organodisilanes, perfluorosilanes, etc., each having a chlorine group or a fluorine group can be used. Organosilanes include acetoxytrimethylsilane, diacetoxydimethylsilane, acetoxytripropylsilane and other organoacetoxysilanes; methoxytrimethylsilane, dimethoxydimethylsilane, trimethylphenoxysilane and other organoalkoxysilanes; trichloromethylsilane, propyltrichlorosilane, Organochlorosilanes such as hexyltrichlorosilane, dodecyltrichlorosilane, dichlorodimethylsilane, dichloroethylphenylsilane; organochloroflurides such as chlorodifluoromethylsilane, dichlorodifluoromethylsilane, dichlorodifluoropropylsilane Orsilane can be mentioned. Further, as perfluorosilane, hexadecafluorodecyltrichlorosilane, heptadecafluorodecyltrichlorosilane, heptadecafluorodecylmonomethyldichlorosilane, heptadecafluorodecyldimethylmonochlorosilane, nonifluorohexyltrichlorosilane, trifluoropropyltrichlorosilane, etc. Can be mentioned. Among these, organosilanes having a chlorine group and a fluorine group, for example, heptadecafluorodecyltrichlorosilane are most preferable.

The above-mentioned organosilane having a hydrolyzable group is applied to a glass fiber paper to which the crossing points of the glass fibers are attached by a binder. The conventional method is to prepare a water repellent glass. Liquid phase methods such as the dipping method, which are widely used for the above, can be used, but the binder of the glass fiber paper that is the base material is dissolved in the organic solvent used in the liquid phase method, and the fibers are separated. Be careful as it may happen.

As a result of earnest research, the present inventors have found that a glass fiber filter having sufficient water resistance can be produced by using a vapor phase method such as a spray method or a chemical vapor surface modification method. Further, the chemical vapor surface modification method is particularly preferable because it has characteristics such as a high reaction rate, no waste liquid is produced, good environmental compatibility, and uniform film-forming property that can be applied to a heterogeneous substrate. Can be used. The thickness of the organosilane layer having a hydrolyzable group is preferably about 0.5 nm to 100 nm, more preferably 2 to 30 nm.
Is.

In other words, the amount of the organosilane having a hydrolyzable group attached per unit weight (g) of the glass fiber dust removal filter of the present invention is 20 to 500 mg.
Is preferred. If the adhesion amount is too small, the water resistance and the dust collection performance of the filter are not improved, and if it is too large, it causes clogging, which is not preferable.

For example, when the chemical vapor surface modification method is used, the degree of vacuum during the treatment may be set so that a sufficient vapor pressure can be obtained, and it is usually 10 Torr although it varies depending on the type of reagent used. The degree is enough. It is effective to heat the substrate in order to accelerate the reaction with the substrate surface. The heating temperature varies depending on the substrate surface substance and the type of treating agent, but when the functional group is a Cl group, the treating temperature of about 80 ° C. is sufficient.

[0013]

EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. Wash the glass fiber HEPA filter (made by Nippon Sheet Glass) with binder with UV / O ₃ (50 ° C-30
Minutes) About 0.1 HEPA filter in the chamber
After setting 8 m2 and reducing the pressure to about 10 Torr with a vacuum pump, the system was closed and heated to 80 ° C. 0.05
mL of heptadecafluorodecyltrichlorosilane (H
FTS) was injected into the chamber using a syringe and vaporized. After reacting for 1 hour as it was, the temperature was raised to 99 ° C. while vacuuming, and excess HFTS in the chamber was removed by a cold trap. As a result, a polymer of heptadecafluorodecyltrichlorosilane (molecular weight
A glass fiber HEPA filter in which the surface of the glass fiber was covered with the film of 582) (thickness: 2.5 nm) was obtained. (Polymer adhesion weight 100 mg per 1 g of HEPA filter) When a water drop was dropped on this sample, it was visually confirmed that the water was repelled and that it was highly hydrophobized. Also, when observed with an electron microscope, it was confirmed by X-ray photoelectron spectroscopy that the glass fibers were bonded by a binder at the intersections thereof and almost all the surfaces of the glass fibers were covered with the HFTS polymer.

Further, in order to quantitatively grasp the performance as a HEPA filter, water resistance, pressure loss, DOP
The transmittance and the I value were evaluated. The I value indicates the efficiency with respect to the pressure loss calculated by the following formula, and it can be said that the larger the I value is, the better the filter is. I = (-ln (P)) / (pressure loss) Here, P = (DOP transmittance%) / 100, and the unit of pressure loss is mmH2O. Fix a test piece (150 mm x 150 mm) between two glass funnels with an air inlet and an outlet, and set it to 5.3.
The pressure loss value was measured by measuring the pressure difference between the upstream side and the downstream side when air was flowed at a wind speed of 3 cm / sec. However, the measurement area of the sample was 100 cm ² . The results for the air filter are shown in Table 1 together with the performance of the untreated sample.

Dioctyl phthalate (DOP) particles having an average particle diameter of 0.3 μm were generated and passed through a test piece to give 0.3
The collection efficiency of μm particles was measured using a light scattering relative densitometer. In this case, the measurement area and the test air volume were 100 cm ² and 32 L / min, respectively.

Attach the test piece to a water resistance tester, raise the room temperature water at a level of 600 mm / min, and measure the water level when water leaks out from three places on the open side of the test piece. The water resistance was evaluated by.

Comparative Example 3 with average fiber diameters of 0.5 μm, 1 μm, and 4 μm
The glass short fibers obtained by mixing the respective types of fibers in the proportions of 30 parts by weight, 50 parts by weight, and 20 parts by weight, respectively,
After being dispersed in the sulfuric acid aqueous solution of No. 4, wet papermaking was performed with a TAPPI machine. $ The obtained wet paper is a fluororesin of the following composition
It was immersed in a silicone resin-containing binder emulsion, drained, and dried at 140 ° C. This fluororesin
The amount of the silicone resin-containing binder attached to the filter paper is 1
The amount per square meter was 4.4 g, which was 6% by weight with respect to the glass fiber constituting the filter paper.

[0018]

[Table 1] =================================== sample water resistance pressure loss DOP transmittance I value ( _{mmH 2 O) (mmH 2 O} ) (%) ----------------------------------- untreated 308 24.9 0.023 0.336 HFTS 644 25.8 0.007 0.371 Treated Fluoro Resin 629 34.0 0.003 0.306 (Comparative Example) ============= ======================

DOP transmission is data for 0.3 μm DOP particles. From this, the water resistance is increased 2.1 times by the HFTS treatment. Also, it can be seen that the DOP transmittance is reduced to about 1/3 with almost no increase in pressure loss, and the dust collection performance is improved. According to the comparative example in which the fluororesin is added, the dust collection performance (DOP transmittance) is improved, but the pressure loss is increased. Comparing with the I value showing the overall performance of the filter, it is clear that the HFTS treatment (invention) has an I value as large as 0.065 as compared with the comparative example.

When static electricity was measured on the HFTS-treated and untreated samples, the half-lives of the generated charges were 35.6 seconds and 25.6 seconds, respectively. Therefore, HFT
It is considered that the S treatment improves the dust collection performance because static electricity is likely to stay and is difficult to escape. The measurement conditions were a relative humidity of 10.6% and an air temperature of 24.3 ° C.

[0021]

Industrial Applicability As described above, the glass fiber dust removal filter of the present invention has excellent water resistance and dust collection performance, and can be used as an air filter for a clean room in the electronics or medical field even under high humidity. , It can also be used in coastal areas.

Further, by using the gas phase method of the present invention, the glass fiber filter can be uniformly processed without breaking the aggregate structure of the glass fibers, so that a glass fiber filter having suitable performance can be obtained.

Claims (2)

[Claims] 1. A dust filter made of glass fiber, the surface of which is treated with an organosilane having a hydrolyzable group. 2. A method for producing a glass fiber dust filter, which comprises contacting and reacting an organosilane having a gaseous hydrolyzable group with a glass fiber dust filter material.