JPS5835722B2 - Ultra-thin film manufacturing method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for producing an ultra-thin film suitable as a homogeneous film that allows liquids and gases to pass therethrough.

Some so-called homogeneous membranes, which are not porous membranes, used for the purpose of permeating liquid or gas, are commercially available in the form of hollow fibers or sheets.

These films are usually the thinnest, from 2 to 30 μm;
It is about 2 to 3μ.

Even when a film is cast deeply using a Dr.Frede under laboratory conditions, the limit is 0.5 μm or more.

The present invention relates to a method for forming an ultra-thin film of 1 μm or less, in which an oily substance spread on a water surface is observed to be colored due to the interference of light, giving it a rainbow-like appearance.

The ultra-thin membrane obtained by the present invention is useful as a selectively permeable membrane for gas separation.

Generally, gas permeates through a homogeneous membrane due to the pressure difference on both sides of the membrane, and the amount of gas permeated is expressed by the following equation.

Here, F is the amount of permeation per unit time, A is the area of the membrane, l
is the film thickness, Pe is the permeability coefficient determined by the type of substance and permeated gas, and JP is the pressure difference (partial pressure difference).

As is clear from the above equation, the amount of permeation F increases as the membrane area increases and the membrane thickness decreases.

Pe is limited by the membrane material, and (P is limited by the pressure pump, etc.), and cannot be changed arbitrarily.

Although it is fairly easy to increase the membrane area A, increasing this will either lead to an increase in the size of the entire permeation device, or require devising various shapes to expand the effective area. A complicated shape causes pressure non-uniformity for gas permeation and does not give favorable results.

Therefore, the most effective means to increase F is to decrease the film thickness l.

Several methods for producing ultra-thin films have already been proposed.

The thinnest ultra-thin film can be obtained by depositing the film on the supporting liquid surface using a Langmuir device with two spreading rods.
- A discontinuous method similar to Blodgett's monolayer manufacturing method is disclosed in JP-A-50-41958 and JP-A-51-89.
It is described in the No. 564 publication.

A continuous method is also described by Lundstrom in US Pat. No. 3,767,737.

The discontinuous method is ultimately the Langmuir-Bl
Although it has the advantage of being able to obtain ultra-thin films in the monomolecular state, such as the Odgett film, continuous film formation is still useful from an industrial standpoint.
In particular, in order to obtain long films, a continuous film forming method is essential.

On the other hand, although the Lundetrom method for manufacturing connected ultra-thin films has various advantages, it also has some limitations.

The major one is that the polymer solution is required to have a higher specific gravity than the support liquid, and since the polymer solution is supplied through the support liquid to the surface of the support liquid via a roll, Non-uniformity of the produced film and uneven thickness are likely to occur.

The present inventors investigated various methods for compensating for the above-mentioned drawbacks and easily and continuously producing ultra-thin films. As a result, the following process was found to be suitable for producing ultra-thin films, and the process of about 1000A to
We have found that ultra-thin films of 1 μm can be easily and continuously produced.

An embodiment of the present invention will be described below with reference to the drawings.

In the apparatus shown in the figure, a solution consisting of a volatile solvent and a polymer having a pre-adjusted permeability and forming a non-porous homogeneous membrane is moved through a fixed speed motor 1, a cylinder 2, and a piston 2'. The liquid is continuously supplied onto the surface of the support liquid 5 at a constant rate by a liquid pump.

The supplied polymer solution immediately spreads on the surface of the support liquid 5 due to interfacial tension with the support liquid 5, the solvent is evaporated or dissolved in the support liquid 5, and a film 11 is formed on the surface of the support liquid 5.

The flow rate of the extruded polymer solution, the speed of the take-up roller 7, the moving speed of the supporting liquid determined by the auxiliary roller 10, and the recovery rate of the solvent from the polymer solution can be controlled as desired. As a result, an ultra-thin film having a desired thickness can be produced without any directional force being applied to the formed film.

The auxiliary roller 10 transfers the support liquid 5 and at the same time adsorbs contaminants floating on the surface of the support liquid,
Produces a constantly fresh supporting liquid surface.

To describe the present invention in more detail with reference to the drawings, it is composed of a polymer that is prepared in advance to a predetermined concentration and that forms a permeable, non-porous homogeneous membrane, and a volatile solvent that dissolves the polymer. The polymer solution 3 has been filtered through a filter with a suitable pore size and is held in the cylinder 2 of a constant rate injection pump.

The constant speed motor 1 and the cylinder 2 are mechanisms for sending out the polymer liquid at a constant speed, and the method for doing so may be a method in which the piston 2 is driven by the constant speed motor 1, or an ordinary method such as extrusion using compressed gas. Any conventional method may be used.

The polymer solution extruded at a constant speed passes through the guide tube 6 and is discharged onto the support liquid 5 from its tip, that is, the nozzle 6'.

The nozzle 6 may be made to protrude from within the support liquid 5 or may be arranged above the support liquid 5, and the arrangement position can be arbitrarily set depending on the film forming conditions.

In the experiments conducted by the present inventors, the support liquid m
It was installed approximately 2 mm above the 100mm height and did not cause any problems.

The structure of the nozzle 6' is preferably such that a cylindrical tube is cut obliquely in the direction of film development.

However, a structure in which the membrane is simply cut flat may be used, and in this case, it is sufficient to install a rear back plate 12 to reflect the expansion of the membrane to the rear.

At the initial stage of film formation, a roller is used to pull up the developed film, and γ is a roller that is placed away from the surface of the supporting liquid to pull up contaminants on the surface of the supporting liquid and move the supporting liquid in the direction in which the solution is developed. Rotate 10 at a constant speed.

The polymer solution discharged from the nozzle 6' is spread in the same direction, but the rotation of the roller 10 makes it easier to spread in the direction of the roller 10.

As a result, dust and other contaminants on the surface of the support liquid are adsorbed onto the surface of the roller 10, making it possible to create a fresh surface of the support liquid.

By bringing the roller 7 into contact with the liquid surface, the film 11 formed on the surface of the supporting liquid comes into contact with the flexible and inert support 8 supplied by the roller 13 and is transferred. It becomes an integrated flat plate-like body 8' and is wound up on a roller 9.

The rotation of the roller T plays the role of a spreading rod in the monomolecular film forming method, and controls the extrusion speed of the polymer solution from the nozzle 6', the rotation speed of the roller T, and the recovery speed of the solvent of the polymer solution. By adjusting, an ultra-thin film with a desired thickness can be obtained.

Furthermore, the rotation of the roll 10 not only removes contaminants on the surface of the support liquid 5, but also creates a slight surface flow in the support liquid 5, thereby accelerating the rate of development of the spontaneously developing film 11. , which facilitates the continuous formation of even thinner films.

The roller length of roller 7 is shorter than that of roller 10, so that the ultra-thin film transferred to the flexible and inert support 8 is
It can cover the entire surface.

The ultra-thin film residue that protrudes from the roller length of the roller 7 is wound up by the roller 10, and the film 11 is formed on the surface of the supporting liquid 50 without stagnation.

According to the method and apparatus of the present invention, compared to Lundstrom's method, the specific gravity of the polymer solution can be selected regardless of the specific gravity of the support liquid 5, and of course, when it is lighter than the support liquid,
Even if the material was heavy, when it was discharged from the nozzle 6', it spread immediately due to surface tension, and it was possible to form a sufficiently thin film 11.

Further, due to the function of the auxiliary roller 10, it was possible to form an even thinner film.

As the polymer for forming the ultra-thin film used in the present invention, virtually any polymer can be used as long as it has a film-forming ability and is soluble in a solvent.

Examples of such polymers include heavy polymers having repeating units selected from organosiloxanes, aromatic ethers, aromatic esters, aliphatic ethers, aliphatic esters, aliphatic hydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons. Union,
Alternatively, it may be a polymer mixture, a copolymer, etc. made of a combination of some of these.

Specific examples include polydimethylsiloxane, vinyl group-containing polydimethylsiloxane, polyphenylene ether, polyvinyl chloride, polymethyl methacrylate, polysulfone, polystyrene, polycarbonate, and other condensation polymers and vinyl polymerization polymers. However, any solvent-soluble type could be used.

The solvent is a general n organic solvent having 1 to 10 carbon atoms, such as aliphatic hydrocarbons, aromatic hydrocarbons, logen-containing hydrocarbons, oxygen-containing hydrocarbons, nitrogen-containing hydrocarbons, sulfur-containing hydrocarbons, Alternatively, one selected from hydrocarbons containing a plurality of elements selected from nitrogen, oxygen, nitrogen, and sulfur, or a mixture of the above solvents is preferable.

For example, when distilled water is used as the support liquid 5, any solvent for dissolving the polymer can be used without any particular restrictions, except for those with very low volatility. Examples include benzene, toluene, xylene, etc. Aromatic hydrocarbons such as dichloromethane, dichloroethane, etc., volatile solvents that are immiscible with water such as logenated hydrocarbons, and compatible solvents such as tetrahydrofuran and dioxane were also fully usable.

When a polymer solution consisting of these polymers and a solvent was formed into a film by the method of the present invention, a film of 1000X to 1μ was constantly formed. , when using polydimethylsiloxane with a molecular weight of 200,000 or more and using benzene as a solvent, at least 75
It was also possible to form a film without pinholes up to about 0A.

Examples of the present invention will be described in detail below.

Example 1 In the figure, an aluminum tank 4 with a width of 50 Crn and a length of 1 m is prepared, and is filled with distilled water 5 as a supporting liquid.

As a polymer solution, a 15% benzene solution of polydimethylsiloxane (molecular weight: about 500,000 gum) was prepared and injected into the 20 part of the cylinder.

While rotating the roller 10, the polymer solution is pumped from the constant speed pump 1VC through the guide tube 6 and from the nozzle 6'.
,c.

/Tll11TL. When the tip of the ultra-thin film 11 spread on the water surface reached the roller 10, the roller 7 was lowered and winding up of the film was started.

As the support 8, a porous polypropylene membrane having a width of 30 CW was used.

Under these conditions, an ultra-thin film of substantially c+5 of polydimersiloxane could be formed on the porous polypropylene support membrane 8 at a speed of 1.5 m per minute.

Example 2 An ultra-thin film was formed in the same manner as in Example 1, except that a dichloromethane 5-functional solution of polycarbonate was used as the polymer solution.

The average film thickness was 6soK.

Example 3 In Example 1, a porous cellulose membrane coated with polyacrylonitrile (porosity: 48) was used as the support 8.

As a result, an ultra-thin film with a substantial film thickness of 1200x was formed.

Example 4 Using the ultra-thin film-polypropylene porous film structure obtained in Example 1 as a support, the same method as in Example 1 was repeated to produce a multilayer film.

A multilayer film with a thickness of 1 sooK was obtained by repeating the process three times.

The results of measuring the gas permeability of the membranes obtained in Example 1 and Example 4 were as follows.

As described above, according to the present invention, an ultra-thin film can be easily obtained in a connected manner.

[Brief explanation of the drawing]

The figure is a sectional view showing an embodiment of the ultra-thin film manufacturing apparatus according to the present invention. 1... Constant speed motor 2... Cylinder, 3... Polymer liquid, 4... Tank, 5...
...Support liquid, 6...Guide tube, 6'.
... Nozzle, 7 ... Winding roller, 8
...Support, 9,10.13...Roller 11...Ultra-thin film, 12...Rear back plate.

Claims (1)

[Claims] 1. A step of preparing a solution consisting of a polymer material and a volatile solvent, and a step of supplying the solution at a constant rate to the surface of a support liquid that is partially soluble or insoluble in the solvent. , spreading the solution on the surface of the supporting liquid to deposit the polymeric material film on the surface of the supporting liquid, and bringing a flexible and inert support into contact with the polymeric material film and continuously pulling it up. A method for producing an ultra-thin film, comprising the steps of: 2. The method for producing an ultra-thin film according to claim 1, characterized in that when the solution is spread on the surface of the support liquid, at least the surface of the support liquid is moved in the direction in which the solution is spread. 3 The polymer material is organosiloxane, aromatic ether, aromatic ester, aliphatic ether, aliphatic ester,
A patent for a polymer having a repeating unit selected from aliphatic hydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons, or a polymer mixture or copolymer made of a combination of some of these. A method for producing an ultra-thin film according to claim 1. 4. The method for producing an ultra-thin film according to claim 1, wherein the polymeric material is polydimethylsiloxane or vinyl group-containing polydimethylsiloxane. 5. The volatile solvent is an organic solvent having 1 to 10 carbon atoms, and this organic solvent is an aliphatic hydrocarbon, aromatic hydrocarbon, halogen-containing hydrocarbon, oxygen-containing hydrocarbon, nitrogen-containing hydrocarbon, sulfur-containing hydrocarbon. The ultra-thin film according to claim 1, which is one or a mixture of two or more selected from hydrogen or hydrocarbons containing multiple elements selected from halogen, oxygen, nitrogen, and sulfur. Production method. 6. The method for producing an ultra-thin film according to claim 1, wherein the volatile solvent is benzene, toluene, or xylene, or a mixture of two or more thereof. 7. The method for producing an ultra-thin film according to claim 1, wherein the volatile solvent is a cyclic ether such as tetrahydrofuran or dioxane. 8. The method for producing an ultra-thin film according to claim 1, wherein the supporting liquid is water. 9. The method for producing an ultra-thin film according to claim 1, wherein the support is a porous polypropylene sheet. 10 A tank containing a support liquid, a liquid injection means for supplying a solution consisting of a polymeric material and a volatile solvent onto the surface of the support liquid at a constant rate, a means for moving the surface of the support liquid in one direction, a flexible and inert An apparatus for producing an ultra-thin film, comprising means for moving the support body toward and away from the surface of the support liquid. 11. Claim 10, wherein the means for moving the supporting liquid comprises a second roller, and the means for bringing the first roller support into and away from the surface of the supporting liquid, and the first roller is longer than the second roller. The ultra-thin film manufacturing apparatus described above.