JPS5833002B2 - Method for manufacturing filter media for water separation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides the following advantages:
The present invention relates to a method of manufacturing a water separation filter material by imparting water repellency.

More specifically, by plasma polymerizing a silicon compound on the surface of a porous sheet, water repellency is imparted to the porous sheet without damaging its original pore properties, thereby producing a water separation filter material. It is about the method.

Hitherto, as a treatment for imparting water repellency to porous sheets such as paper and nonwoven fabrics, a method of coating or impregnating them with a water repellent substance such as silicone has been known.

However, according to this method, the silicone etc. penetrates into the inside of the porous material and covers the entire surface of the fibers that make up this material, so the original pore properties of the porous material are damaged. It is inevitable that air permeability and liquid permeability will decrease.

The present inventors have overcome the drawbacks of such conventional methods, and have developed a method using simple operations without damaging the properties of the pores in the porous sheet.
As a result of intensive research to develop a method that can only impart water repellency, we discovered that the purpose could be achieved by plasma polymerizing a gaseous silicon compound on the surface of a porous sheet, and based on this knowledge, we Based on these findings, the present invention has been completed.

That is, the present invention provides a filter material for water separation, characterized in that a porous sheet is brought into contact with a gaseous silicon compound and subjected to plasma polymerization by high-frequency excitation, thereby imparting water repellency while maintaining porosity. The present invention provides a method for manufacturing.

Porous sheets used in the method of the present invention include:
In addition to fibrous sheets such as paper, nonwoven fabrics, and woven fabrics, there are also thin silica gel sheets and breathable plastic films.

The silicon compounds used in the method of the present invention include gasifiable organosilicon compounds, such as tetraalkylsilanes such as tetramethylsilane, trimethylethylsilane, and dimethyldiethylsilane; Examples include dialkylaminotrialkylsilanes such as hexamethyldisilazane, hexaalkyldisilazane such as hexaethyldisilazane, and various siloxanes.

The treatment time of the method of the present invention varies to some extent depending on other treatment conditions, but is usually 1 minute to 30 minutes, and it is possible to form a polymer film with a thickness of several tens to several thousand angstroms.

Next, one example of an embodiment of the method of the present invention will be described with reference to the accompanying drawings.

The drawing is a schematic explanatory diagram of a plasma reaction tube suitable for carrying out the method of the present invention, and a material to be treated 6 is charged inside the plasma reaction tube 1, which is passed through an inlet 4 into a dispersion tube. 2
The silicon compound gas is brought into contact with the silicon compound gas excited by the high frequency coil 3, and plasma polymerization occurs on the surface thereof.

Gaseous substances and unreacted silicon compounds produced as by-products during this polymerization are discharged to the outside of the reaction tube through the discharge port 5.

For polymerization at this time, the pressure is 5×10” torr to 1×10
”Torr vacuum degree and 5 watts to 100 watts
A power of t is used.

The filter material for water separation obtained by the present invention does not allow water to pass through, but it can easily pass gases and organic solvents such as halogenated hydrocarbons, alcohol, benzene, toluene, etc., so it can be used to separate water-containing organic solvents. It can be used as a material etc.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 In the plasma reaction tube shown in the drawings, the main body 1 has an inner diameter of 4.
A Pyrex glass tube with a length of 4crIL and 40crIL was used, and a piece of filter paper (2
), and after exhausting to about 1X10-4 Torr, open the inlet port 4.
Tetramethylsilane from 6xI Q Torrs
Introduce.

Once the pressure becomes constant, 13.56MHH is applied to the induction coil.
A high frequency wave of z is applied to generate plasma.

After processing for 1.0 minutes, the application of high frequency is stopped, the reaction tube is opened, and the filter paper piece is taken out.

In this way, a piece of filter paper was obtained which had a polymeric coating of about 100 people on its surface.

This piece of filter paper did not allow any water to pass through it, but it allowed benzene and ethanol to pass through it in the same way as before the treatment.

In the same manner as above using various different silicon compounds,
A high frequency wave with a power of 50 Watts was applied at the degree of vacuum shown in the table below to obtain a polymerized film having a thickness per minute shown in the table below.

Example 2 An acetylcellulose porous film (pore diameter, approximately 1 μm) was placed in a plasma reaction tube, and the temperature was approximately 1xio-4 Torr.
exhaust to.

Hexamethyldisilazane, 5X10-2To from the inlet
rr is introduced, and after the pressure becomes constant, the high frequency is
When the polymerization reaction is carried out in the shade for a minute, a polymer film of about 1200 layers can be obtained on the surface.

Example 3 Place a thin silica gel plate for chromatography (2.5crfLX 7.5CIrL) in a plasma reaction tube and
Evacuate to 1O-4 Torr.

Diethylaminotrimethylsilane at 6×10 −2 Torr is introduced through the inlet, and polymerization is performed for about 5 minutes.

In this way, approximately 800 polymeric coatings can be obtained.

Organic solvents such as ethanol, benzene, and toluene can easily pass through this thin plate, but water repels it and does not allow it to penetrate.

[Brief explanation of drawings]

The drawing shows one of the plasma reaction tubes for carrying out the method of the present invention.
This is a schematic cross-sectional view showing an example, and the reference numeral 1 in the figure indicates the reaction tube main body;
2 is a silicon compound gas dispersion tube, and 3 is a high frequency coil.

Claims (1)

[Claims] 1. Bringing a gaseous silicon compound into contact with a porous sheet,
A method for producing a filter material for water separation, characterized by performing plasma polymerization by high frequency excitation to impart water repellency while maintaining porosity. 2. The method according to claim 1, wherein the porous sheet is paper, nonwoven fabric, or woven fabric. 3. The method according to claim 1, wherein the silicon compound is siloxane, tetraalkylsilane, dialkylaminotrialkylsilane or hexaalkyldisilazane.