JP2008055256A - Gas separation membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organopolysiroxane crosslinked membrane which is thin and excellent in oxygen-nitrogen separating ability, and also provide a manufacturing method of an organopolysiroxane crosslinked membrane which easily manufactures an organopolysiroxane crosslinked membrane which is thin and excellent in oxygen/nitrogen separating ability. <P>SOLUTION: The organopolysiroxane crosslinked membrane is a membrane which is formed by reacting an organopolysiroxane having two or more hydrosilyl groups with an organopolysiroxane having two or more vinyl groups by a hydrosilylation catalyst. The membrane concerned is at most 1 μm in thickness and its oxygen/nitrogen separating factor is at least 1.6 at ordinary temperature. A manufacturing method of the membrane is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organopolysiloxane crosslinked membrane that can be suitably used as a gas separation membrane and a method for producing the same.

  In general, a gas separation membrane is prepared by forming a gas separation functional layer on a porous support membrane. At this time, it is necessary to make the separation functional layer thin to increase the gas permeation rate (the gas throughput per unit time). However, organopolysiloxanes currently used as gas separation membranes are difficult to be made thinner than 1 micrometer (Patent Documents 1 and 2, etc.).

Japanese Examined Patent Publication No. 6-77673 JP-A-6-269649

The problem to be solved by the present invention is to provide an organopolysiloxane crosslinked membrane having a small thickness and excellent oxygen-nitrogen separation ability.
Another problem to be solved by the present invention is a method for producing an organopolysiloxane crosslinked membrane that can easily produce an organopolysiloxane crosslinked membrane having a small thickness and excellent oxygen-nitrogen separation ability. Is to provide.

The above-mentioned problems to be solved by the present invention have been solved by the following <1> and <2>. It is shown below with <3>-<13> which are preferable embodiments.
<1> A film formed by reacting an organopolysiloxane having two or more hydrosilyl groups and an organopolysiloxane having two or more vinyl groups with a hydrosilylation catalyst, and the thickness of the film is 1 μm or less, An organopolysiloxane cross-linked membrane, wherein the membrane has an oxygen / nitrogen separation coefficient at room temperature of 1.6 or more,
<2> An organopolysiloxane having two or more hydrosilyl groups, an organopolysiloxane having two or more vinyl groups, and an organic solvent solution containing a hydrosilylation catalyst, the hydrosilylation reaction is partially advanced, and the organic solvent A step of thickening the solution, a step of adjusting the thickened organic solvent solution to a dilute solution having an organopolysiloxane concentration of 6% by weight or less, a step of applying the dilute solution into a film, and a hydrosilylation reaction And a step of removing the organic solvent to obtain an organopolysiloxane crosslinked film in this order, wherein the organopolysiloxane crosslinked film has a thickness of 1 μm or less, and the organopolysiloxane crosslinked film is oxygen / nitrogen at room temperature. A method for producing a crosslinked organopolysiloxane membrane, wherein the separation factor is 1.6 or more,
<3> The method for producing a crosslinked organopolysiloxane film according to <2>, wherein the organopolysiloxane having two or more hydrosilyl groups has a weight average molecular weight of 1,500 to 8,000,
<4> The method for producing a crosslinked organopolysiloxane film according to <2>, wherein the organopolysiloxane having two or more vinyl groups has a weight average molecular weight of 15,000 to 250,000,
<5> The organopolysiloxane having two or more hydrosilyl groups is a dimethylpolysiloxane having two or more hydrosilyl groups, and the organopolysiloxane having two or more vinyl groups is a dimethylpolysiloxane having two or more vinyl groups. The method for producing an organopolysiloxane crosslinked film according to <2> above,
<6> Production of an organopolysiloxane crosslinked membrane according to the above <2>, wherein an organopolysiloxane crosslinked membrane is formed on the porous support membrane, and the average pore diameter of the porous support membrane is 10 to 250 nm. Method,
<7> The method for producing an organopolysiloxane crosslinked film according to <2>, wherein the concentration of the diluted solution is 2 to 5% by weight,
<8> The method for producing a crosslinked organopolysiloxane film according to <2>, wherein the thickness of the crosslinked organopolysiloxane film is 0.7 μm or less,
<9> The crosslinked organopolysiloxane film according to <1>, wherein the organopolysiloxane having two or more hydrosilyl groups has a weight average molecular weight of 1,500 to 8,000,
<10> The organopolysiloxane crosslinked film according to <1>, wherein the organopolysiloxane having two or more vinyl groups has a weight average molecular weight of 15,000 to 250,000.
<11> An organopolysiloxane having two or more hydrosilyl groups is a dimethylpolysiloxane having two or more hydrosilyl groups, and an organopolysiloxane having two or more vinyl groups is a dimethylpolysiloxane having two or more vinyl groups. The organopolysiloxane crosslinked film according to <1> above,
<12> The organopolysiloxane crosslinked membrane according to the above <1>, wherein the organopolysiloxane crosslinked membrane is formed on the porous support membrane, and the average pore diameter of the porous support membrane is 10 to 250 nm,
<13> The organopolysiloxane crosslinked film according to <1>, wherein the thickness of the crosslinked organopolysiloxane film is 0.7 μm or less.

According to the present invention, it is possible to provide an organopolysiloxane crosslinked membrane having a small thickness and excellent oxygen-nitrogen separation ability.
Moreover, according to this invention, the manufacturing method of the organopolysiloxane crosslinked film which can manufacture easily the organopolysiloxane crosslinked film with thin thickness and excellent oxygen-nitrogen separation ability can be provided.

The organopolysiloxane crosslinked film of the present invention is a film formed by reacting an organopolysiloxane having two or more hydrosilyl groups and an organopolysiloxane having two or more vinyl groups with a hydrosilylation reaction catalyst. The thickness is 1 μm or less, and the oxygen / nitrogen separation coefficient at room temperature of the membrane is 1.6 or more.
Hereinafter, the crosslinked organopolysiloxane film of the present invention and the production method thereof will be described in detail.

<Organopolysiloxane cross-linked film>
The organopolysiloxane crosslinked film of the present invention is a film formed by reacting an organopolysiloxane having two or more hydrosilyl groups and an organopolysiloxane having two or more vinyl groups with a hydrosilylation reaction catalyst.

(Organopolysiloxane having two or more hydrosilyl groups)
The organopolysiloxane having two or more hydrosilyl groups that can be used in the present invention is an organopolysiloxane having two or more Si-H groups, and hydrosilylation reaction with an organopolysiloxane having two or more vinyl groups. As long as it can perform a cross-linked structure, it may be a linear or branched organopolysiloxane. The organopolysiloxane having two or more hydrosilyl groups may be used alone or in combination of two or more.
The organo group that the organopolysiloxane having two or more hydrosilyl groups has is a group selected from the group consisting of an alkyl group, an aryl group, and an aralkyl group from the viewpoint of availability and stability during the hydrosilylation reaction. Preferably, the group is more preferably a group selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 21 carbon atoms. More preferred is an alkyl group of 20, and particularly preferred is a methyl group.
The alkyl group, aryl group and aralkyl group in the organo group may have a substituent. Examples of the substituent include an alkyl group, an aryl group, and a fluorine atom. The substituent may further have a substituent if possible. The alkyl group in the organo group and the alkyl part of the aralkyl group may have a ring structure. Further, if possible, two organo groups may be bonded to form a ring structure.

  Specific examples of the organopolysiloxane having two or more hydrosilyl groups that can be used in the present invention include organopolysiloxanes represented by the following formula (I).

（式（I）中、ｎは１以上の整数を表し、Ｒ^h1〜Ｒ^h3、ｎ個存在するＲ^h4及びＲ^h5、並びに、Ｒ^h6〜Ｒ^h8のうち少なくとも２つは水素原子であり、水素原子である以外のＲ^h1〜Ｒ^h3、ｎ個存在するＲ^h4及びＲ^h5、並びに、Ｒ^h6〜Ｒ^h8はそれぞれ独立に、アルキル基、アリール基又はアラルキル基を表し、ｎ個存在するＲ^h4及びＲ^h5は同じであっても異なっていてもよい。）

(In the formula (I), n represents an integer of 1 or more, R ^{h1 to} R ^h3 , n R ^h4 and R ^h5 , and at least two of R ^{h6 to} R ^h8 are hydrogen atoms, R ^{h1 to} R ^h3 other than being a hydrogen atom, n existing R ^h4 and R ^h5 , and R ^{h6 to} R ^h8 each independently represents an alkyl group, an aryl group, or an aralkyl group, and n existing R ^h4 and ^Rh5 may be the same or different.)

N in the formula (I) represents an integer of 1 or more, and from the viewpoint of ease of handling at the time of reaction such as volatility and viscosity, an average value of n in the organopolysiloxane having two or more hydrosilyl groups used in the present invention. Is preferably 10 to 200.
In the formula (I), R ^{h1 to} R ^h3 , n existing R ^h4 and R ^h5 , and at least two of R ^{h6 to} R ^h8 are hydrogen atoms, and n existing R ^h4 and R ^h5 More preferably, at least two of them are hydrogen atoms. It is preferable to have a hydrosilyl group on the silicon inside the organopolysiloxane because a crosslinked structure can be formed without reducing the reactivity in the hydrosilylation reaction.
The organopolysiloxane having 2 or more hydrosilyl groups preferably has 3 or more hydrosilyl groups.
In formula (I), R ^{h1 to} R ^h3 other than being a hydrogen atom, n R ^h4 and R ^h5 , and R ^{h6 to} R ^h8 represent an alkyl group, an aryl group, or an aralkyl group, and are easily available. From the standpoint of stability and stability at the time of hydrosilylation reaction, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 21 carbon atoms is preferable. The alkyl group is more preferably a methyl group or a phenyl group, and particularly preferably a methyl group.
The alkyl group, aryl group and aralkyl group in R ^{h1 to} R ^h8 may have a substituent.
Examples of the substituent include an alkyl group, an aryl group, and a fluorine atom. The substituent may further have a substituent if possible. The alkyl group of R ^{h1 to} R ^h8 and the alkyl part of the aralkyl group may have a ring structure. Further, if possible, two of R ^{h1 to} R ^h3 , n existing R ^h4 and R ^h5 , and R ^{h6 to} R ^h8 may be bonded to form a ring structure.

  The weight average molecular weight of the organopolysiloxane having two or more hydrosilyl groups that can be used in the present invention is preferably 1,500 to 8,000, more preferably 2,000 to 5,000, More preferably, it is 2,500-3,500. The above range is preferable because industrial productivity is good in terms of ease of handling at the time of reaction such as volatility and viscosity.

(Organopolysiloxane having two or more vinyl groups)
The organopolysiloxane having two or more vinyl groups that can be used in the present invention is an organopolysiloxane having two or more vinyl groups, and performs a hydrosilylation reaction with an organopolysiloxane having two or more hydrosilyl groups, There is no particular limitation as long as it can take a crosslinked structure, and it may be a linear or branched organopolysiloxane. The organopolysiloxane having two or more vinyl groups may be used alone or in combination of two or more.
The organo group possessed by the organopolysiloxane having two or more vinyl groups is synonymous with the organo group possessed by the organopolysiloxane having two or more hydrosilyl groups, and the preferred range is also the same.

  Specific examples of the organopolysiloxane having two or more vinyl groups that can be used in the present invention include organopolysiloxanes represented by the following formula (II).

（式（I）中、ｍは１以上の整数を表し、Ｒ^v1〜Ｒ^v3、ｍ個存在するＲ^v4及びＲ^v5、並びに、Ｒ^v6〜Ｒ^v8のうち少なくとも２つはビニル基を含む基であり、水素原子である以外のＲ^v1〜Ｒ^v3、ｍ個存在するＲ^v4及びＲ^v5、並びに、Ｒ^v6〜Ｒ^v8はそれぞれ独立に、アルキル基、アリール基又はアラルキル基を表し、ｍ個存在するＲ^v4及びＲ^v5は同じであっても異なっていてもよい。）

(In formula (I), m represents an integer of 1 or more, R ^v1 to R ^v3, m pieces R ^v4 and R ^v5 present, and, a group containing at least two vinyl groups of R ^v6 to R ^v8 R ^{v1 to} R ^v3 other than being a hydrogen atom, m R ^v4 and R ^v5 , and R ^{v6 to} R ^v8 each independently represents an alkyl group, an aryl group or an aralkyl group, m R ^v4 and R ^{v5 present} may be the same or different.)

M in the formula (II) represents an integer of 1 or more, and from the viewpoint of ease of handling at the time of reaction such as volatility and viscosity, the average value of m in the organopolysiloxane having two or more vinyl groups used in the present invention. Is preferably 100 to 5,000.
The group containing a vinyl group in R ^{v1 to} R ^v8 in the formula (II) is a vinyl group or a vinyl group via a group in which two or more alkylene groups, arylene groups, or alkyl groups and / or aryl groups are bonded. Is a group bonded to a silicon atom, and is preferably a vinyl group.
The vinyl group in the group containing a vinyl group may be an unsubstituted vinyl group or a vinyl group substituted by 1 to 3 with an alkyl group, an aryl group, and / or an aralkyl group. From this point, an unsubstituted vinyl group is preferable.
In the formula (II), R ^{v1 to} R ^v3 , m existing R ^v4 and R ^v5 , and at least two of R ^{v6 to} R ^v8 are groups containing a vinyl group, and R ^{v1 to} R ^v3 and R ^v3 More preferably, at least two of ^{v6 to Rv8} are vinyl group-containing groups. It is preferable to have a vinyl group at the terminal of the organopolysiloxane because the reactivity in the hydrosilylation reaction is excellent compared to the case of having a vinyl group inside.
In the formula (II), R ^{v1 to} R ^v3 other than a group containing a vinyl group, m R ^v4 and R ^v5 , and R ^{v6 to} R ^v8 represent an alkyl group, an aryl group, or an aralkyl group. .
The alkyl group, aryl group and aralkyl group in R ^{v1 to} R ^{v8 have the same meanings as} the alkyl group, aryl group and aralkyl group in R ^{h1 to} R ^h8 , and the preferred ranges are also the same.

  The weight average molecular weight of the organopolysiloxane having two or more vinyl groups that can be used in the present invention is preferably 15,000 to 250,000, more preferably 20,000 to 200,000, More preferably, it is 30,000-150,000. The above range is preferable because industrial productivity is good in terms of ease of handling at the time of reaction such as volatility and viscosity.

(Hydrosilylation catalyst)
The hydrosilylation catalyst that can be used in the present invention only needs to have a catalytic action in the hydrosilylation reaction, and a known hydrosilylation catalyst can be used. The hydrosilylation catalyst may be a homogeneous catalyst or a heterogeneous catalyst.
The hydrosilylation catalyst is preferably a group 4, 8, 9, or 10 metal catalyst from the viewpoint of reactivity or reaction rate, and is a Pt, Pd, Rh, Ir, or Ru system. More preferred is a catalyst, and even more preferred is a Pt-based catalyst.
The Pt-based catalyst is preferably a platinum complex such as alcohol, xylene, or vinyl siloxane, more preferably a platinum complex of divinyl siloxane or cyclic vinyl siloxane, and still more preferably a platinum complex of divinyl disiloxane.
In addition, the reaction time (thickening time) can be controlled by using a known reaction inhibitor if necessary (Kunio Ito, “Silicone Handbook”, Nikkan Kogyo Shimbun, 1990, p. 386-387). reference).

Moreover, the thickness of the crosslinked organopolysiloxane film of the present invention is 1 μm or less, preferably 0.7 μm or less, more preferably 0.01 to 0.7 μm, and more preferably 0.02 to 0.02. More preferably, it is 7 μm.
When the thickness of the crosslinked membrane is 1 μm or less, the gas permeation rate can be increased, and an efficient gas separation system can be constructed.

The organopolysiloxane crosslinked membrane of the present invention has an oxygen / nitrogen separation coefficient at room temperature of 1.6 or more. When the oxygen / nitrogen separation coefficient at room temperature of the crosslinked membrane is 1.6 or more, the separation efficiency is sufficient and an efficient gas separation system can be constructed.
The method for measuring the oxygen / nitrogen separation coefficient is not particularly limited, and a known method can be used. For example, a pressure of 50 psig (psi gauge, 1 psi = 6,894.757 Pa) is applied to the supply side by the volume method. It is preferable to use a method of measuring the gas permeation amount with a soap film flow meter connected to the permeation side.
More specifically, the gas permeability of oxygen and nitrogen can be performed at a normal temperature (22 ° C.) at a supply side gas pressure of 50 psig / permeation side pressure of 0 psig by a constant pressure-variable volume gas measurement method. A schematic diagram of a gas permeation measuring apparatus that can be suitably used in the present invention is shown in FIG. The gas permeation measuring apparatus shown in FIG. 1 includes a permeation cell 10 in which a membrane sample 12 to be measured is sandwiched between a supply side member 14 and a permeation side member 16, a soap film flow meter 18, a pressure gauge 20, a regulator 22, and various gas cylinders 24a. ˜24b, purge valve 26, stop valves 28a and 28b, valve 30, and piping 32 connecting them.
The gas that has permeated through the membrane 12 set in the permeation cell 10 is guided to the soap film flow meter 18, and after measuring the volumetric flow rate (dV / dt (cm ³ / sec)) per unit time, The bundle J (cm ³ (STP) / (cm ² · sec · cmHg)) can be calculated.

In the above formula, p is the supply side pressure (cmHg), T is the measurement temperature (K), and A is the effective transmission area (cm ² ).
Further, the oxygen / nitrogen separation coefficient α can be determined by determining the ratio of the permeated flux of oxygen and nitrogen (J _O2 / J _N2 ) determined for each.

The crosslinked organopolysiloxane film of the present invention comprises a raw material containing, in addition to the above-described components, an organopolysiloxane having one hydrosilyl group, an organopolysiloxane having one vinyl group, and / or another siloxane compound. May be used. Known additives such as reinforcing agents and heat-resistant agents used in addition-type silicone rubbers can be added as needed when the organopolysiloxane crosslinked film of the present invention is produced.
Further, the crosslinked organopolysiloxane film of the present invention may be a film further subjected to crosslinking by radiation or plasma particles such as gamma rays, vulcanization such as peroxide vulcanization, addition reaction vulcanization, condensation reaction vulcanization, and the like. Good.
Regarding additives and vulcanization such as reinforcing agents and heat-resistant agents, reference can be made to Kunio Ito, “Silicone Handbook”, Nikkan Kogyo Shimbun, 1990.

<Method for producing organopolysiloxane crosslinked film>
The method for producing a crosslinked organopolysiloxane film of the present invention (hereinafter also simply referred to as “the production method of the present invention”) includes an organopolysiloxane having two or more hydrosilyl groups, an organopolysiloxane having two or more vinyl groups, In addition, a process of partially proceeding a hydrosilylation reaction using an organic solvent solution containing a hydrosilylation catalyst to thicken the organic solvent solution (hereinafter, also referred to as “thickening process”), the thickened organic A step of adjusting the solvent solution to a dilute solution having an organopolysiloxane concentration of 6% by weight or less (hereinafter also referred to as “dilution step”), and a step of applying the dilute solution in a film form (hereinafter also referred to as “application step”). ), A process for further hydrosilylation reaction (hereinafter also referred to as “reaction process”), and a process for removing the organic solvent to obtain an organopolysiloxane crosslinked film. (Hereinafter also referred to as “removing step”) in this order, the organopolysiloxane crosslinked film has a thickness of 1 μm or less, and the organopolysiloxane crosslinked film has an oxygen / nitrogen separation factor of 1.6 at room temperature. It is the above.
Moreover, the organopolysiloxane crosslinked film of the present invention can be suitably produced by the method for producing an organopolysiloxane crosslinked film of the present invention.

(Thickening process)
The method for producing a crosslinked organopolysiloxane film of the present invention comprises hydrosilylation using an organic solvent solution containing an organopolysiloxane having two or more hydrosilyl groups, an organopolysiloxane having two or more vinyl groups, and a hydrosilylation catalyst. Including a step of increasing the viscosity of the organic solvent solution (thickening step).

  The organopolysiloxane having two or more hydrosilyl groups, the organopolysiloxane having two or more vinyl groups, and the hydrosilylation catalyst that can be used in the production method of the present invention are the same as described above.

The organic solvent that can be used in the production method of the present invention is not particularly limited as long as it is an organic solvent that does not affect the hydrosilylation reaction, and a known solvent used in the hydrosilylation reaction can be used. The organic solvent is preferably a nonpolar solvent, more preferably an alkane or an aromatic hydrocarbon, and particularly preferably isooctane. The organic solvent is liquid at normal temperature, and preferably has a boiling point of 60 to 250 ° C. at normal pressure, more preferably 80 to 150 ° C. at normal pressure.
Moreover, the said organic solvent may be used individually by 1 type, and 2 or more types may be mixed and used for it in arbitrary ratios.

  The amount of the hydrosilylation catalyst used in the thickening step is not particularly limited as long as the hydrosilylation reaction proceeds. However, a sufficient reaction rate can be obtained, and the residual amount of catalyst in the resulting crosslinked film can be reduced. Therefore, it is preferably 1 to 10,000 ppm and more preferably 10 to 5,000 ppm with respect to the total weight of the organic solvent solution.

As a means for partially promoting the hydrosilylation reaction and thickening the organic solvent solution, it is sufficient that the hydrosilylation reaction partially proceeds, or the hydrosilylation reaction is not proceeding at all, or the hydrosilylation reaction proceeds excessively. If it does not become a gelled state, there is no particular limitation.
The thickening step may be performed at room temperature or may be performed by heating (preheating). However, since the progress of the reaction can be easily controlled, the hydrosilylation reaction is partially advanced by heating (preheating). It is preferable to use a method of thickening the organic solvent solution.
There is no restriction | limiting in particular in the heating means in the said thickening process, What is necessary is just to heat the said organic solvent solution by a well-known means.
The heating temperature in the thickening step may be any temperature at which the hydrosilylation reaction proceeds, and can be appropriately adjusted depending on the catalyst, substrate, and solvent used. A preferable heating temperature is 60 to 120 ° C, more preferably 70 to 100 ° C, and further preferably 75 to 90 ° C.
The heating time in the thickening step depends on the catalyst and substrate used, the heating temperature, and the like. For example, when the platinum catalyst concentration is 200 ppm and the heating temperature is 80 ° C., it is 30 seconds or more and less than 1,000 seconds. Is preferable, 100 to 800 seconds is more preferable, and 200 to 700 seconds is particularly preferable.
In the thickening step, the hydrosilylation reaction is partially advanced to increase the viscosity until the relative viscosity of the organic solvent solution reaches 150 to 300% of the value before the hydrosilylation reaction. Is preferred.
A method for measuring the relative viscosity is not particularly limited, and a known method can be used. For example, a solution intrinsic viscosity method using an Ostwald-Fenske viscometer can be preferably exemplified.
Also, the method for measuring the intrinsic viscosity is not particularly limited, and a known method can be used. For example, it is preferably measured by an Ostwald-Fenske viscometer.
When the heating temperature, heating time and / or relative viscosity change are within the above ranges, defects such as pinholes and voids can be prevented when the crosslinked film is used, and dilution in the dilution step is easily performed. be able to.

(Dilution process)
The method for producing a crosslinked organopolysiloxane film of the present invention includes a step (dilution step) of adjusting the organic solvent solution obtained by the thickening step to a dilute solution having an organopolysiloxane concentration of 6% by weight or less.
The “organopolysiloxane concentration” refers to the total concentration of an organopolysiloxane having two or more hydrosilyl groups, an organopolysiloxane having two or more vinyl groups, and those produced from the hydrosilylation reaction. .
The organopolysiloxane concentration of the diluted solution is 6% by weight or less, preferably 0.1 to 6% by weight, more preferably 0.5 to 5.5% by weight, and 2 to 5% by weight. % Is more preferable. Within the above range, a cross-linked membrane having excellent oxygen-nitrogen separation properties and free from defects such as pinholes and voids can be continuously produced simply and industrially with a sufficiently thin thickness.
When the organopolysiloxane concentration in the organic solvent solution obtained by the thickening step is 6% by weight or less, the organic solvent may be further diluted by dilution, or may not be diluted.
As the organic solvent used for diluting the organic solvent solution, the same organic solvents as those described above can be used. Moreover, the organic solvent used for dilution may be used individually by 1 type, may mix and use 2 or more types by arbitrary ratios, and is used for the organic solvent solution obtained by the said preheating process. It may be the same as or different from the organic solvent used.

(Coating process)
The method for producing a crosslinked organopolysiloxane film of the present invention includes a step of applying the dilute solution in a film form (application step).
The organopolysiloxane crosslinked film of the present invention can be applied in the form of a film using a known method. For example, the dilute solution can be used to form a film by a solvent casting method. That is, the thin solution is cast on a glass plate, a Teflon (registered trademark) plate, a stainless steel plate mirror-finished by chrome plating or the like, or a support made of an endless belt, etc. Can be applied.
The organopolysiloxane crosslinked membrane of the present invention can also be produced as a composite membrane by casting a dilute solution directly on a porous support membrane.
Examples of the porous support membrane that can be used in the present invention include polyolefins such as polyethylene and polypropylene, fluororesins such as polytetrafluoroethylene and polyvinylidene fluoride, polyester, polyurethane, nylon, polysulfone, and polyetherimide. .
It is preferable that the porous support membrane has a thickness of 10 to 100 μm and an average pore size of 10 to 250 nm.
The thickness of the coating film obtained by coating the dilute solution into a film is preferably such that the dry film thickness is 1 μm or less, more preferably 0.7 μm or less, and 0.01 to 0.7 μm. Is more preferable, and 0.02-0.7 μm is particularly preferable.

(Reaction process)
The method for producing a crosslinked organopolysiloxane film of the present invention further includes a step (reaction step) of performing a hydrosilylation reaction after the diluted solution is applied in a film form.
The amount of the hydrosilylation catalyst used in the reaction step is not particularly limited as long as the hydrosilylation reaction proceeds. Further, if necessary, a hydrosilylation catalyst may be further added after the thickening step, preferably before the coating step.

The heating means in the reaction step is not particularly limited, and the dilute solution applied in a film shape by a known means may be heated.
The heating temperature in the reaction step may be any temperature at which the hydrosilylation reaction proceeds and can be appropriately adjusted depending on the catalyst, substrate, and solvent to be used. A preferable heating temperature is 60 to 120 ° C, more preferably 70 to 100 ° C, and further preferably 75 to 85 ° C.
The heating time in the reaction step depends on the catalyst and substrate used, the heating temperature, the film thickness, the concentration of the solution, etc., but is not particularly limited as long as the hydrosilylation reaction proceeds, and the length of the hydrosilylation reaction is almost completed. It is preferable to set the time. A preferable heating time is 1 to 60 minutes, and more preferably 10 to 30 minutes.

(Removal process)
The method for producing a crosslinked organopolysiloxane film of the present invention includes a step of removing an organic solvent to obtain an crosslinked organopolysiloxane film (removal step).
The removing step may be performed simultaneously with the reaction step or after the reaction step, but is preferably performed simultaneously with the reaction step from the viewpoint of simplification of the step.
The solvent removing means in the removing step is not particularly limited as long as the organic solvent in the coating film can be removed, and a known means can be used. For example, heating by the heating means described above or solvent distillation under reduced pressure can be used. Lastly, means such as air drying can be mentioned. Further, the organic solvent may be removed by combining a plurality of means.
Also, for example, when a coating film is formed on a support as described above, the film is peeled off from the support before being completely dried, dried to a desired dry thickness by biaxial stretching, and a crosslinked film You may get

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to an Example.
Moreover, as long as there is no notice in particular, the instrument and apparatus etc. which are used in the following Examples can use a commercially available or well-known instrument and apparatus suitably if it is a range which does not deviate from the meaning of this invention.

(Reference Example 1)
Using KE-103 (manufactured by Shin-Etsu Chemical Co., Ltd.), a two-component addition type RTV silicone rubber, the coating solution was made into a 15 wt% isooctane solution, and a curing agent (CAT-103: manufactured by Shin-Etsu Chemical Co., Ltd.) Was prepared with a 5 wt% formulation and the solution was preheated at 80 ° C. before coating. The preheating time was changed from 30 seconds to 720 seconds, and a necessary amount of isooctane was added immediately after the heating so that the total concentration was 10% by weight. The prepared coating solution is preheated at 80 ° C. for a predetermined time, and then is applied to a porous membrane support made of polysulfone (PSF) (molecular cut-off = 10,000, Ultra Filter: manufactured by Advantec). It apply | coated using the casting knife and heat-dried at 80 degreeC for 15 minute (s). After the heat drying, the oxygen and nitrogen permeability of the membrane sample was measured. The KE-103 coating solution prepared in the same manner was cast in a cast dish, a bulk film sample having a thickness of about 1 mm (1,000 μm) was formed, and a gas permeation experiment was conducted. This was used for the calculation of the film thickness of the cross-linked film of the composite film provided with the organopolysiloxane cross-linked film of the present invention. Gas permeation measurement was performed by a volumetric method in which a pressure (P) of 50 psig was applied to the supply side at a temperature (T) of 22 ° C., and the gas permeation amount was measured with a soap film flow meter connected to the permeation side. The measurement results are shown in Table 1 and FIG.

  When the preheating time was 30 seconds, the hydroxylation reaction did not proceed, and when the preheating time was 800 seconds or more, gelation started in the solution, so that isooctane could not be diluted.

Next, the influence of the partial crosslinking reaction due to the preheating was examined by measuring the viscosity of the coating solution. Intrinsic viscosity was measured by the solution intrinsic viscosity method using an Ostwald-Fenske viscometer. The results are shown in Table 2 and FIG.
The measurement results in Table 2 and FIG. 3 where the intrinsic viscosity is 0.4 (dl / g) and the oxygen / nitrogen separation factor is 1.0 are the results of samples that were not preheated at all. In some cases, it was impossible to perform a defect-free coating.

(Analysis of organopolysiloxane)
About the organopolysiloxane having two terminal vinyl groups and the organopolysiloxane having two or more hydrosilyl groups used in Examples, the molecular weight and the like were analyzed by ²⁹ Si NMR and gel permeation chromatography (GPC), respectively. The analysis results are shown in Tables 3 and 4 below.

(Example 1)
The mixing ratio of the organopolysiloxane having two or more hydrosilyl groups and the organopolysiloxane having two or more vinyl groups is based on the analysis results shown in Tables 1 and 2 above. The mixture was prepared to 1 mol, and a platinum complex catalyst (divinyltetramethyldisiloxane platinum complex) was added at a concentration of 200 ppm with respect to the total amount of polysiloxane used, and then isooctane was added to make a 10 wt% solution. This solution was preheated at 80 ° C. for 300 seconds before coating. Immediately after heating, the required amount of isooctane was added to give a total concentration of 5 wt% or 2 wt%. The prepared coating solution was applied to a polysulfone (PSF) porous membrane support (molecular cut-off = 10,000, Ultra Filter: manufactured by Advantec) with or without a casting knife. For 15 minutes. After the heat drying, the oxygen and nitrogen permeability of the membrane sample was measured.

In addition, each coating solution prepared in the same manner was cast in a cast petri dish, a sample of a bulk film having a thickness of 0.5 to 1 mm was formed, a gas permeation experiment was performed, and the cross-linking prepared on the porous membrane support This was used to calculate the apparent film thickness of the film.
Gas permeation measurement is a method of measuring the gas permeation amount by a soap film flow meter connected to the permeation side by applying a pressure (P) of 50 psig to the supply side at a temperature (T) of 22 ° C. by the volume method as described above. Was used.
In addition, if a defect (pinhole or the like) occurs in the separation functional layer, the limit point at which the oxygen-nitrogen separation property as a non-porous membrane cannot be maintained is 90% of the oxygen-nitrogen separation value in the non-porous membrane. The point that disappears was evaluated as a critical point. This value of 90% is also a reference value used for the process evaluation of the membrane module when considering the balance between the initial performance of the system and the apparatus cost (running cost) in the existing gas membrane separation system.

  When DMS-V35, DMS-V42 and DMS-V52 having different dimethylsiloxy chain lengths were combined with HMS-301 (9.59 mol%) having the largest hydrosilyl group content, the film thickness was sufficiently increased. The measurement results of oxygen / nitrogen permeation separation at 22 ° C. are shown in Table 5 below. Any cross-linked membrane was obtained as a membrane excellent in oxygen / nitrogen separation.

  Tables 6 to 8 show the measurement results of oxygen-nitrogen separation properties for the samples coated with a final concentration solution of 5% by weight, and the results plotted against the apparent thickness of the crosslinked membrane are shown in FIGS. Shown in In FIGS. 4 to 6, ▲ represents a measured value in a sample whose coating was adjusted without using a casting knife, and ● represents a measured value in a sample coated with a film thickness adjusted with a casting knife. Neither coating method had a difference in oxygen nitrogen permeation measurement.

In the samples of DMS-V35 and DMS-V42, it can be seen that the decrease in oxygen-nitrogen separation starts from an average thickness of around 0.8 to 0.9 μm. This suggests that this is the limit at which so-called membrane defects begin to occur, in which the coated crosslinked membrane starts to form pores such as pinholes, and as a result, the separation performance of the non-porous membrane cannot be maintained. On the other hand, in the sample film using DMS-V52, it can be seen that the limit thickness at which this film defect begins to occur is shifted to a thickness of about 0.6 μm.
However, in the DMS-V52 sample, the viscosity of the 5% by weight adjustment solution before coating was considerably higher than the other two samples (DMS-V35 and DMS-V42). For this reason, in order to remove the possibility of the influence on the coating limit thickness due to high viscosity, the same experiment was conducted at a thinner adjustment concentration of 2% by weight. The results are shown in Tables 9 to 11 and FIGS.

As for the coating results at 2% by weight, in the case of DMS-V35 and DMS-V42 (Table 9 (FIG. 7) and Table 10 (FIG. 8)), the estimated average thickness is 0.8 as in the case of 5% by weight. From around ˜0.9 μm, a drop in oxygen and nitrogen separation appeared. And in DMS-V52 (Table 11 (FIG. 9)), it shifted to the direction thinner than the result of 5 weight%, and the fall of oxygen nitrogen separation appeared from about 0.4 micrometer vicinity.
The limit thicknesses of the samples are summarized in Table 12 below.

(Example 2)
In order to see the influence of the density of cross-linking points in the molecule on the separation of oxygen and nitrogen, dimethylpolysiloxane cross-linked films with different cross-link densities were prepared and examined using dimethylpolysiloxanes with different hydrosilyl group contents. . A dimethylpolysiloxane having two or more vinyl groups uses DMS-V35 having a molecular weight (Mw) of 34,200, and dimethylpolysiloxanes having two or more hydrosilyl groups are HMS-031, HMS-071, An organopolysiloxane crosslinked film was prepared in the same manner as in Example 1 except that HMS-151 and HMS-301 were used, respectively, and the diluted solution after the preheating was changed to a 5 wt% isooctane solution.
Table 13 shows the results of measurement of oxygen-nitrogen permeability and oxygen-nitrogen separability in the organopolysiloxane crosslinked membrane. Moreover, the result of having plotted the measurement result with respect to the density | concentration of the hydrosilyl group in the said dimethylpolysiloxane is shown in FIG.

The oxygen and nitrogen permeation fluxes tended to decrease when the hydrosilyl group concentration decreased from 1.54 mol% to 5.38 mol% and then increased at 9.59 mol%. In addition, the oxygen-nitrogen separability increased to 5.38 mol%, and then decreased at 9.59 mol%.
In relation to the permeability and separation of oxygen and nitrogen, in the early stage when the concentration of hydrosilyl group increases, the permeability decreases as the number of crosslinking points (crosslink density) in the polymer increases, and the permeability decreases. Was shown to increase in selectivity.

It is the schematic of an example of the gas permeation | transmission measuring apparatus which can be used for this invention. It is a figure which shows the fluctuation | variation of the oxygen / nitrogen separation coefficient of a film | membrane by the change of the preheating time at the time of using 2 liquid addition type | mold RTV silicone rubber. It is a figure which shows the fluctuation | variation of the oxygen / nitrogen separation coefficient of a film | membrane by the change of the intrinsic viscosity after a preheating at the time of using 2 liquid addition type | mold RTV silicone rubber. It is a figure which shows the measurement result of the organopolysiloxane crosslinked film of this invention produced by apply | coating as a 5 weight% dilute solution using DMS-V35 and HMS-301. It is a figure which shows the measurement result of the organopolysiloxane crosslinked film of this invention produced using DMS-V42 and HMS-301 and apply | coating as a 5 weight% dilute solution. It is a figure which shows the measurement result of the organopolysiloxane crosslinked film of this invention produced by apply | coating as a 5 weight% dilute solution using DMS-V52 and HMS-301. It is a figure which shows the measurement result of the organopolysiloxane crosslinked film of this invention produced using DMS-V35 and HMS-301 and apply | coating as a 2 weight% dilute solution. It is a figure which shows the measurement result of the organopolysiloxane crosslinked film of this invention produced using DMS-V42 and HMS-301 and apply | coating as a 2 weight% dilute solution. It is a figure which shows the measurement result of the organopolysiloxane crosslinked film of this invention produced using DMS-V52 and HMS-301 and apply | coating as a 2 weight% dilute solution. It is a figure which shows the measurement result of the organopolysiloxane crosslinked film of this invention produced using DMS-V35 and various hydrosilyl group containing organopolysiloxane and apply | coating as a 5 weight% dilute solution.

Explanation of symbols

10: Permeation cell 12: Sample membrane 14: Cell supply side 16: Cell permeation side 18: Soap membrane flow meter 20: Pressure gauge 22: Regulators 24a, 24b, 24c, 24d: Gas cylinder 26: Purge valves 28a, 28b: Stop Valve 30: Valve

Claims (8)

A film formed by reacting an organopolysiloxane having two or more hydrosilyl groups and an organopolysiloxane having two or more vinyl groups with a hydrosilylation catalyst;
The thickness of the film is 1 μm or less;
The organopolysiloxane crosslinked membrane, wherein the membrane has an oxygen / nitrogen separation coefficient at room temperature of 1.6 or more. An organic solvent solution containing an organopolysiloxane having two or more hydrosilyl groups, an organopolysiloxane having two or more vinyl groups, and a hydrosilylation catalyst is used to partially advance the hydrosilylation reaction to increase the organic solvent solution. The step of sticking,
Adjusting the thickened organic solvent solution to a dilute solution having an organopolysiloxane concentration of 6% by weight or less,
Applying the dilute solution into a film;
A further hydrosilylation reaction step, and
Including the step of removing the organic solvent to obtain the organopolysiloxane crosslinked film in this order,
The organopolysiloxane crosslinked film has a thickness of 1 μm or less,
The method for producing a crosslinked organopolysiloxane film, wherein the organopolysiloxane crosslinked film has an oxygen / nitrogen separation coefficient at room temperature of 1.6 or more.   The method for producing a crosslinked organopolysiloxane film according to claim 2, wherein the weight average molecular weight of the organopolysiloxane having two or more hydrosilyl groups is 1,500 to 8,000.   The method for producing a crosslinked organopolysiloxane film according to claim 2, wherein the organopolysiloxane having two or more vinyl groups has a weight average molecular weight of 15,000 to 250,000.   The organopolysiloxane having two or more hydrosilyl groups is a dimethylpolysiloxane having two or more hydrosilyl groups, and the organopolysiloxane having two or more vinyl groups is a dimethylpolysiloxane having two or more vinyl groups. The manufacturing method of the organopolysiloxane crosslinked film of description.   The method for producing a crosslinked organopolysiloxane film according to claim 2, wherein the crosslinked organopolysiloxane film is formed on a porous support film, and the average pore diameter of the porous support film is 10 to 250 nm.   The method for producing a crosslinked organopolysiloxane film according to claim 2, wherein the dilute solution has an organopolysiloxane concentration of 2 to 5% by weight.   The method for producing a crosslinked organopolysiloxane film according to claim 2, wherein the crosslinked organopolysiloxane film has a thickness of 0.7 µm or less.

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