JPH0259032A - Surface modified film made of polysulfone and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain a surface modified film having a high filtering speed by irradiating a porous membrane made of polysulfone with ultraviolet rays at room temp. under atmospheric pressure. CONSTITUTION:A porous membrane made of polysulfone is irradiated with ultraviolet rays having proper intensity at room temp. under atmospheric pressure while an irradiation distance and an irradiation time are properly set. For example, the proper intensity of ultraviolet rays is about 600W, the proper irradiation distance is about 25cm and the proper irradiation time is 1-20min. The obtained modified membrane is extremely low in the compatibility with protein and solves the sudden lowering of a filtering speed due to the adsorption of protein and keeps a high filtering speed. Therefore, a filtering time in a wide range of filtering operation such as the filtering of protein is shortened to a large extent.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a method for surface modification of a porous polymer membrane made of polysulfone. It is strong and thermally stable, and is used in a wide range of membrane filtration technologies. However, the crotch made of a hydrophobic substrate cannot avoid protein adsorption, and the membrane pores are blocked by proteins. A sudden drop in the filtration rate was inevitable.

[Prior Art] Many methods for surface modification of porous polymer membranes containing polysulfone have been reported, and a representative example is one using graft polymerization technology. In a surface treatment method using a porous polymer membrane, a polymerizable M-form, and an appropriate crosslinking agent, it is difficult to modify the surface properties while avoiding clogging of the membrane pores.

In addition, surface grafting methods using plasma discharge treatment (JP-A-62-2G2705, JP-A-133-140)
Publication No. I) requires processing under vacuum, and the processing steps and processing equipment are complicated, making industrial production very difficult.

[Problems to be Solved by the Invention] The present invention maintains the physical strength and chemical resistance that are characteristic of polysulfone, which is a hydrophobic substrate, and also eliminates protein absorption, which is a major drawback of porous membranes formed from polysulfone. z
The purpose of the present invention is to provide a surface-modified membrane that solves the sudden drop in filtration rate caused by No. 1 and maintains a high filtration rate, and a method for manufacturing the same.

[Means for Solving the Problem] As a result of intensive research in view of the current situation as described in 1-1, the present inventor has found that
We have arrived at the present invention.

That is, the present invention provides a porous membrane made of polysulfone (1
By surface-modifying only the porous membrane surface without destroying the structure due to blockage, we have developed a surface-modified membrane that maintains the physical strength and chemical resistance that are characteristic of polysulfone, and has a high filtration rate. (manufacturing) method.

The present invention will be explained in detail below.

After washing the polysulfone porous membrane with water, the surface is modified by irradiating it with ultraviolet light.

The ultraviolet light source used for surface modification ranges from about 10W to 10W.
It is possible to use up to 0[)W or more by using an appropriate irradiation distance and irradiation time. UV irradiation is always 1
M + Since it is carried out under normal pressure and does not require special conditions, the processing equipment and processing steps are also very simple.

The irradiation time of ultraviolet rays depends on the irradiation distance and intensity of ultraviolet rays, but for example, when the intensity of ultraviolet rays is GOOW and the irradiation distance is 25 cm, irradiation treatment for 1 to 20 minutes is appropriate, and for -ga, it is preferably 3 to IO minutes. . If the irradiation time is too short, the effect will not be achieved, and if the irradiation time is too long, surface hydrophilization will be hindered, and the desired performance will not be achieved.

The contact angle of the surface of the surface-modified membrane obtained by the present invention with pure water is 60° or less, preferably 35° or less. In addition, the protective membrane has extremely low affinity for proteins and maintains a high filtration rate by solving the major drawback of porous membranes made of polysulfone, which is a hydrophobic substrate, by adsorbing proteins and causing a rapid decrease in filtration rate.

[Effects of the Invention] According to the present invention, the surface of a porous membrane can be modified by simply irradiating the polysulfone porous membrane with ultraviolet rays at room temperature and pressure. In addition, since the surface-modified porous polysulfone membrane obtained by the present invention maintains a much higher filtration rate than an untreated polysulfone porous membrane, the use of a protective membrane It is possible to significantly reduce the filtration time by 1d in a wide range of filtration operations such as protein filtration.

[Examples] Examples will be given to explain the present invention in more detail, but the present invention is not limited to these Examples.

Example 1 Diameter 43111111. A polysulfone membrane with a molecular weight cut-off of 300,000 was washed with water and exposed to ultraviolet irradiation equipment (manufactured by Ushio Electric Co., Ltd., MiniCure 450) at room temperature and under normal pressure.
), UV intensity eoow, irradiation distance Is, 25cm
Ultraviolet irradiation treatment was performed at 1° for 3.5.7 minutes. 0.5% γ-globulin for the four types of membranes obtained.

0.3596 bovine serum albumin, 0.12% myoglobin.

(1. Using 50 ml of protein mixed solution in which Ol 9ji vitamin B1 □ was dissolved in physiological saline, use a filtration device (manufactured by Advantechn 1., Ultra Holder 〇IIP-43)
), the limit d! at a pressure of 1 kg l'/cfi! The membrane was subjected to i-filtration, and changes in filtration rate were examined and compared with untreated membranes.

The contact angle of untreated polysulfone film and surface-modified film with pure water was measured, and as shown in Table 1, the contact angle decreased as the UV irradiation time increased, and the contact angle decreased after 5 minutes of UV irradiation. By taking the minimum value, it was confirmed that the membrane surface was made hydrophilic and surface modification was carried out.

Table 1 In addition, when the filtration rates of the untreated polysulfone membrane and the surface-modified membrane were determined as shown in Figure 1, the surface-modified membrane always maintained a higher filtration rate than the untreated membrane. It was confirmed that the blockage of membrane pores by proteins was suppressed, and the contact angle was the minimum (1 (~1)
(-(The maximum value of the filtration rate was observed at 5 minutes relative to the time.

Example 2 A polysulfone membrane having a diameter of 43n+++ and a molecular weight cut off of 1,000,000 was washed with water and subjected to ultraviolet irradiation treatment for 5 minutes at room temperature and pressure at a strong ultraviolet ray +ieoow and an irradiation distance of 125 cm. 0.1% for the obtained film
-Blue dextran (molecular weight 2,000,000)
Using a 50-year-old solution, a filtration device (Ultra Holder UIIP-43 manufactured by Atvanchik Co., Ltd.) +,:, pressure 1 kg r/cd f,: "C ultrafiltration was performed, and changes in filtration rate rU were examined. The ratio with the membrane is ?-1.

The filtration rate of untreated polysaliphon membrane and surface-modified membrane was 41
As shown in Figure 2, the surface-modified membrane always maintains a higher filtration rate than the untreated membrane.
The effectiveness of the surface modified membrane was confirmed.

Example 3 A polysulfon membrane having a diameter of 43 mm and molecular fractions of to and ooo was washed with water and subjected to ultraviolet irradiation treatment at room temperature and pressure at an ultraviolet intensity of tioOW and an irradiation distance of 25 cm for 1.3.5 minutes. For the three types of membranes obtained, 50ml of the same sample solution as in Example 1 was used, and a pressure of 1kgf/
Ultrafiltration was performed using e4, and changes in filtration rate were examined and compared with untreated membranes.

The filtration rates of the untreated polysulfone membrane and the surface-modified membrane were measured, and as shown in Figure 3, the surface-modified membrane had a
It maintains a very high filtration rate compared to untreated membranes,
It can be confirmed that the clogging of membrane pores by proteins is suppressed.

[Brief explanation of the drawing]

Figures 1.2.3 show changes in filtration rate with filtration time for the surface-modified membrane and untreated membrane in Examples 1 and 2.3, respectively. Figure 1 Figure 2 O: Untreated film: UV irradiation for 5 minutes

Claims (2)

[Claims] (1) A surface-modified polysulfone membrane with a hydrophilic surface. (2) The method for producing a surface-modified membrane according to claim (1), which comprises irradiating the polysulfone porous membrane with ultraviolet rays.