JPS59225703A - Porous membrane and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain a membrane having an extremely thin dense layer and good in gas separation capacity and anti-thrombotic property, by using a silicone compound comprising a block copolymer consisting of a compound having at least one aromatic ring in the main chain or side chain thereof and an organosiloxane compound. CONSTITUTION:This silicone compound is a polymer comprising a repeating unit represented by a structural formula and dissolved in dichloromethane, chloroform and carbon tetrachloride. The obtained solution is cast to form a film which is, in turn, immersed in a non-solvent, usually, water and gelled to obtain a porous membrane. As compared with a usual support obtained by the competing reaction of plasma polymerization and plasma sputtering, plasma polymerization is exclusively and preferentially generated and, therefore, the accumulation of a stable polymer membrane is enabled and crater shaped defect or crack parts are almost eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silicon compound porous membrane and a method for manufacturing the same.

The basic functions of membranes are substance separation and shielding, and in recent years, research and development for their industrial and medical applications has been active.

In the industrial field, we use seawater desalination, pure water production, refining and enrichment of uranium-enriched foods, adjustment of Co and H2 gas ratios for basic chemical synthesis using carbon oxide and hydrogen, and improvement of combustion efficiency. In the medical field, oxygen enrichment systems are widely used, including oxygen enrichment systems, artificial lungs, artificial kidneys, capsule membranes for local drug administration, artificial blood vessels, and even antithrombotic catheters.

Among them, research on organic porous membranes has made rapid progress since the research on UF and RO membranes, and the social needs for them are increasing in the industrial and medical fields.

Up until now, typical examples have been cellulose-based porous membranes such as cellulose acetate, engineering plastic porous membranes such as polysulfone, amide-based porous membranes, polypropylene porous membranes, and fluorine-based porous membranes such as tetrafluoroethylene. However, the problem with these materials is that they have low gas permeation rates when applied to gas separation membranes, and they do not have good antithrombotic properties when used in medical applications. was a problem. Therefore, it has been essential to compose the materials mentioned above or to perform complicated surface treatments.

However, the silicon compound used in the present invention has high gas permeability and antithrombotic properties unique to silicone rubber, and has excellent flexibility, and furthermore, it can be formed into a dense layer without complex compounding or surface treatment. Materials that can be applied to industrial and medical fields can be obtained by applying them alone or by simply subjecting them to a simple surface treatment.

The silicon compound used in the present invention is obtained by condensation polymerization of organosiloxane and an organic substance having at least one aromatic ring in the main chain or side chain, and has a repeating structural unit whose structural formula is represented by the following formula: It is.

R.

1 (2 Although it has excellent starvation properties and gas permeability, it has low self-retention properties, and it is difficult to obtain a thin film by itself from the viewpoint of strength.Furthermore, it is difficult to obtain a film with good gas separation performance and antithrombotic properties. In order to achieve high gas permeability, we can process extremely thin films of less than 1 μm by forming a porous structure and then depositing a polymerized thin film using plasma polymerization under glow discharge. We have discovered that it is possible to freely select a material from a wide range of materials that can maintain its properties and at the same time have high gas selective permeability, and with regard to antithrombotic properties, materials that have good antithrombotic properties.

Specifically, a silicon compound made of a block copolymer of a compound having at least 1 degree aromatic ring in its main chain or side chain and an organosiloxane compound has a mysteriously low decomposition in a plasma atmosphere due to glow discharge, and Compared to normal supports where polymerization and plasma sputtering compete with each other, plasma polymerization occurs preferentially, making it possible to deposit stable polymeric thin films, resulting in depolymerization of the support and hydrogen generation. Most of the crater-like defects and cracks that are thought to be caused by this will disappear.

When a compound without an aromatic ring, such as dimethylpolysiloxane, is used as a support and exposed to a glow discharge atmosphere, the weight decrease due to plasma sputtering takes precedence over the weight increase due to plasma polymerization, resulting in stable quality. It becomes difficult to obtain a composite membrane.

The silicon compound used in the present invention has a structural formula; Although it is a polymer, it may of course be other than this.

R,, R2 is, for example, -H, -CH,, -(EE>,
-CH= CH2゜-CH1,000CH-CH8, -c=cH
etc. can be mentioned. Of course, it may be other than this.

These silicon compounds include chlorine-based solvents such as dichloromethane, chloroform, carbon tetrachloride, and reliclane, amide-based solvents such as dimethylacetamide, cyclic ethers such as tetrahydrofuran, aromatic hydrocarbon-based solvents such as cresolbenzene, toluene, etc. - Soluble in ketones such as methyl ethyl ketone and acetone. Furthermore, since it exhibits solubility in cyclic nitrogen-containing solvents such as N.methyl-2-pyrrolidone, a solvent with high solubility and a solvent with low solubility can be mixed and used.

It is also possible to adjust the viscosity of the solution, the porosity, the shape of the pores, and the thickness of the dense layer by adjusting the solution concentration, type of solvent, combination of solvents, addition of a swelling agent, type of coagulant, etc.

The swelling agent referred to herein is one that promotes the formation of pores in the membrane, and does not necessarily need to be extracted at the time of membrane formation, but may form a part of the porous membrane.

Among the above-mentioned solvents, dimethylamide is particularly preferred because it can easily form a porous structure without adding a swelling agent or the like.

Furthermore, it is also possible to manipulate the pore size and porosity by adding a second solvent.

Next, these solutions are uniformly cast onto a support plate using a doctor knife, and after the casting, they are immersed in a non-solvent, usually water or ethanol, to gel. A silicon compound porous membrane is obtained by partially evaporating the solvent and then gelling it. Of course, it is also possible to create a hollow body using a tubular nozzle.

The properties of porous membranes are affected by the solution concentration, type of solvent, amount of swelling agent, type of coagulant, etc. Generally, the gas permeability increases as the amount of swelling agent increases, but the membrane becomes thicker. Too much may lead to a decrease in strength and non-uniformity.

In the present invention, it is possible to repair defective parts by using the above-mentioned porous membrane as it is or by laminating a thin film on the surface of the dense layer side of the porous membrane by plasma polymerization. It is possible to increase the permselectivity without significantly lowering it, and it is also possible to form a surface layer with better antithrombotic properties.

The plasma polymerized layer is deposited to a thickness of less than 1 micron, preferably less than 0.3 micron. For example, the pressure in the system is reduced to 5 torr or less, preferably 2 torr or less, a mixed gas of a non-polymerizable gas and a polymerizable gas is introduced into the system, and a high frequency wave is applied to the system at a predetermined output, for example, 5 to 500W, preferably 20W. When glow discharge is performed, the polymerizable gas undergoes plasma polymerization and is deposited as a thin film on the porous silicon compound film. Since the thickness of this thin film increases approximately in proportion to the length of glow discharge time or the flow rate of the polymerizable gas, it can be adjusted to an arbitrary thickness, for example, 1 μm or 0.3 μm.

The deposition thickness also increases or decreases depending on the increase or decrease in the output during glow discharge, but these film forming conditions are within a range that can be easily optimized by those familiar with the technology in this field.

In any case, in the present invention, it is necessary to deposit a defect-free uniform polymer film with the above-mentioned thickness.

i) One selection criterion for the polymerizable gas is plasma polymerization.
Since the thin film is an extremely thin layer with a thickness of 1μ or 0.3μ or less, when used for gas separation, it does not allow one component of the mixed gas to be separated to permeate as much as possible.
It has excellent antithrombotic properties when used in artificial lungs, artificial organs, artificial blood vessels, catheters, etc. In order to satisfy this criterion, common plasma-polymerizable monoorganosilane compounds such as ethylene and styrene are preferably used.

Examples of 8th-class carbon-containing compounds include t-butyl compounds such as t-butylamine, pentene derivatives such as 4-methyl-1-pentene, octenes such as 1-octene, and tylsilane, which also uses isoprene, hexamethyl Examples include silanes such as disilazane, methyldichlorosilane, and methyltrichlorosilane. Furthermore, organic silane compounds having an unsaturated bond, such as trimethylvinylsilane, dimethylvinylchlorosilane, vinyltrichlorosilane, methylvinyldichlorosilane, methyltrivinylsilane, allyltrimethylsilane, ethanyltrimethylsilane, and the like are more preferably used.

18-Evaluation of gas permeability characteristics is performed using the unit of gas permeability coefficient P-cn?・ty'tz2・sec −(yHHg
It is expressed using , which is converted into a thickness of 1 cPn of material. On the other hand, in the case of a composite membrane, the permeation rate Q of the thickness of the material itself is expressed in units of 0 mHg = cm8/cm'' 1see 0 mHg. ] A difference of 0 times occurs. Therefore, the properties that are actually required are the permeation rate and the thickness of the membrane.

Next, this will be further explained using examples.

Example-1 Polydimethylsiloxane-bisphenol A carbonate block copolymer (PSO99; manufactured by Chisso ■) 20
A solution prepared by dissolving 80 parts by weight of dimethylacetamide was cast onto a glass plate to a thickness of 300μ, and the glass plate was immersed in distilled water. After the film solidified and peeled off, it was washed with water for 2 hours, and heated to 50°C. The mixture was air-dried for 2 hours to obtain a porous membrane with a thickness of about 80 μm. Obtained 14- The obtained film had gloss on the surface and lacked gloss on the back surface.

Scanning electron micrographs of the cross section are shown in Figures 1-A to 1-C.

The porosity was measured and was approximately 4.0%.

When we measured the strength, Tensile strength: 37Kg Tensile elongation; 180% Tear strength: 11 K9/cm Met.

When the gas permeation characteristics of this porous membrane were evaluated using air as a raw material gas, QOgΦ5.5 X 10-5cm8/cm" ・se
e −(ygHHgP02 + 5.OX 10− c
m8・cry'crr?・sec --gα(Qo2
/QN2) + 1.8 and ivy.

Example 2 Trimethylvinylsilane was applied to the surface of the silicon compound porous membrane at a flow rate of 1.0 cm8.
/min into the system, and the output of 2'OW is 30
A plasma polymerized film was deposited by performing glow discharge in a reaction densifier for a minute.

When gas permeation characteristics were evaluated, QO2+ 2. OX 10' cm3/cm2・se
ccmHgα(QoQ/QN2) = 2.9.

Example-3 16 parts by weight of polydimethylsiloxane/bisphenol A carbonate block copolymer was added to polycarbonate) (
S-2000 (manufactured by Mitsubishi Gas Chemical) 4 parts by weight Sesimeta solution dissolved in 80 parts by weight of tetramethane was placed on a glass plate for 3 minutes.
The glass plate was cast to a thickness of 0.00μ, immersed in ethanol together with the glass plate, and after the film solidified and peeled off, it was washed with water for 2 hours and heated at 50°C for 2 hours.
A porous membrane with a thickness of about 100 μm was obtained by ventilation drying for a period of time.

When the porosity was measured, it was 7%.

Tensile strength: 11'7 Ky/cm" Tensile elongation: 2
00% Tear strength: 33 Ky/cm Gas permeability: QO2: 1.6 x 10'cm87cm2-
see ・cmHgP02+1.6X10-8crn"
im”sec・m1gα(Qoa/QN2) +
It was 2.4.

Comparative Example-1 20 parts by weight of polydimethylsiloxane/bisphenol A carbonate block copolymer was mixed with 80 parts by weight of dichloromethane.
The solution dissolved in parts by weight was cast onto a glass plate to a thickness of 300 μm, and the glass plate was immersed in distilled water. After the film solidified and peeled off, it was washed with water for 2 hours and dried with ventilation at 50°C for 2 hours. A nearly transparent film with a thickness of about 60 μm was obtained.

The porosity was about 1%.

When gas permeation characteristics were evaluated, Qo2+2.8X10' i〆→2・SeC・σH
1.7×l0-8crn8・cw/crn2 in gPog
-8eC-m1gα(Q□g/QN2) was 2.1.

(Effects of the Invention) The silicon compound porous membrane obtained by the present invention has the following disadvantages of conventional porous membranes and asymmetric pore membranes: low gas permeation rate, poor antithrombotic properties, and lack of flexibility. It can be said that it is suitable for application to gas separation membranes, liquid membrane supports, artificial lungs, artificial blood vessels, and catheters.

Furthermore, since the processing process is simple, it is possible to carry out the process in a more energy-saving and resource-saving manner.

[Brief explanation of drawings]

Figures 1-A-C are scanning electron micrographs of a cross-section of a silicon compound porous membrane, and Figure 1-A is near the surface with a dense layer.
Center part view-1-C is a photograph of the back side. All magnifications are XIo, 000. − is. 18- A X 10.000 B XIo, 000

Claims (1)

[Claims] (1) The average thickness of the dense layer on one surface of the porous membrane is 8 μm.
In the following, the average porosity of the porous membrane is 80% or more, and the porous membrane is mainly composed of a structural formula 1X; an organic group R1, R, i having at least one aromatic ring in the main chain or side chain; A porous membrane comprising a silicon compound represented by functional groups m and n; natural numbers. (2) The porous membrane according to claim 1, wherein the silicon compound is selected from polydimethylsiloxane and sphenol A carbonate block copolymers and polydimethylsiloxane-α-methylstyrene block copolymers. . (3) A porous film comprising at least one plasma polymerized thin film formed by glow discharge deposited on the dense layer on one surface of the porous film made of a silicon compound according to claim 1. (4) The porous film according to claim 3, wherein the plasma polymerized thin film is made of an organic silane compound. (5) In order to obtain a porous film made of a silicon compound according to claim 1, structural formula; Functional groups m, n; forming a film of a solution containing a silicon compound represented by a natural number, a solvent and, if necessary, a swelling agent, and contacting it with a coagulant,
A method for producing a porous membrane, characterized by removing a solvent and drying it. (6) The method for producing a porous membrane according to claim 5, wherein the silicon compound is a polydimethylsiloxane-bisphenol A carbonate block copolymer or a polydimethylsiloxane-α-methylstyrene block copolymer. (7) i The liquid was selected from dichloromethane, chloroform, trichlene, benzene, toluene, THE
6. The method for producing a porous membrane according to claim 5, which comprises using a species or a mixture of two or more species as a solvent and a swelling agent. (8) The method for producing a porous membrane according to claim 5, wherein the solvent is dimethyl amide. (9) The method for producing a porous membrane according to claim 5, wherein the structural formula of the swelling agent consists of repeating units having at least one aromatic ring in the main chain or side chain. 6. The method for producing a porous membrane according to claim 5, wherein the θ1 silicon compound is a polydimethylsiloxane-bisphenol A carbonate block copolymer and the swelling agent is polycarbonate. (11) The silicon compound is polydimethylsiloxane-α
Claim 5, characterized in that the swelling agent in the methylstyrene block copolymer is α-methylstyrene.
A method for producing a porous membrane as described in Section 1. A plasma polymerized film is deposited on the surface of a dense layer of a porous film made of a silicon compound obtained by the method of claim 5 of θ by glow discharge while supplying a polymerizable monomer in an atmosphere of 0.5 torr or less. A method for producing a porous membrane characterized by having cells. 13. The method for producing a porous membrane according to claim 12, wherein the α-frame polymerizable monomer is an organic silane compound.