JP4525329B2 - Continuous production method of electrolyte membrane - Google Patents

Description

The present invention relates to a method for continuously producing an electrolyte membrane. More specifically, the present invention relates to a method for continuously producing an electrolyte membrane capable of efficiently and continuously obtaining an electrolyte membrane in which an electrolyte polymer is filled in pores of a porous substrate.
INDUSTRIAL APPLICABILITY The present invention can be used in batteries such as fuel cells and redox flow batteries, various devices in electrolysis, separation membranes and the like.

An electrolyte membrane in which a porous substrate is filled with an electrolyte polymer obtained by polymerizing an ion exchange group or a monomer that can be converted into an ion exchange group (hereinafter referred to as “ion exchange ability monomer”) is used in many applications. Yes. For example, a fuel cell that is one type of electrochemical device is known. In recent years, this fuel cell has been greatly improved in performance due to improvements in electrolyte membrane and catalyst technology, and is being developed for low-emission vehicles. Such an electrolyte membrane is manufactured by impregnating a porous base material with an ion exchange capacity monomer or the like and then polymerizing the ion exchange capacity monomer or the like.
Moreover, the method of coat | covering the both sides of a porous base material with the polyester film which is a peeling material at the time of this superposition | polymerization, and then heating under nitrogen pressurization is known (patent document 1).

However, when an electrolyte membrane is produced by this method, the electrolyte polymer is generated not only inside the pores of the porous substrate, but also on the surface of the porous substrate, and the performance of the electrolyte membrane is reduced, so an excess polymer. Need to be removed. This excess polymer is conventionally removed by a method such as scraping with a plastic blade or the like. Also disclosed is a method of removing the ion exchange resin on the surface of the porous substrate by contacting with an oxidizing agent such as hydrogen peroxide or ozone (Patent Document 2).
However, these documents do not disclose a method for continuously and efficiently producing an electrolyte membrane in which an electrolyte polymer is filled in pores of a porous substrate.

  On the other hand, the present inventors continuously carry the porous substrate and impregnate the porous substrate with a polymer precursor containing an ion exchangeable monomer. Resin films are continuously supplied on both sides of the precursor-impregnated sheet impregnated with the polymer precursor, and the polymer precursor is polymerized in a state where the precursor-impregnated sheet is sandwiched between the two resin films. Proposed a continuous production method of a functional film comprising a polymerization process for producing a polymer, a film peeling process for peeling the two resin films, and a polymer removal process for removing the polymer attached to the surface ( Japanese Patent Application No. 2003-31841).

  However, when an electrolyte membrane is produced by this method, a resin film is continuously supplied to both surfaces of the precursor-impregnated sheet, and the precursor-impregnated sheet is sandwiched between the two resin films and roll laminated. In addition, there is a problem that excessive polymer precursor protrudes and adheres to the laminating roller for contamination. Furthermore, since the polymer precursor adhering to the roller adheres again to the continuously transported resin film and is cured in the polymerization process to become an adhesive polymer, it is difficult to reuse the resin film thereafter. It will squeeze. Moreover, when the dried polymer precursor adhering on the roller adheres to the surface of the resin film, this shields the ultraviolet rays when polymerizing by irradiating the ultraviolet rays, thereby partially causing insufficient polymerization. In other words, the polymer precursor adhering to the roller obstructs the step of sandwiching the resin film and the polymerization step, which makes it difficult to continuously produce the electrolyte membrane.

JP-A-11-335473 JP 2001-157823 A

  The present invention has been made in view of the above situation, and when a precursor-impregnated sheet is sandwiched between two resin films, the polymer precursor protruding from the side of the film adheres to the laminating roller. In particular, the present invention relates to a method for continuously producing an electrolyte membrane capable of continuously and efficiently obtaining an electrolyte membrane, and in particular, using a porous substrate that is continuously conveyed, the electrolyte membrane is continuously and efficiently produced. It aims at providing the continuous manufacturing method which can be obtained.

The present invention is as follows.
1. In the method for producing an electrolyte membrane, comprising at least the following steps (1) to (3), the step (2) prevents adhesion of the polymer precursor protruding from the resin film to the laminating roller. A method for continuously producing an electrolyte membrane, wherein
(1) an impregnation step of continuously conveying a porous substrate and impregnating the porous substrate with a polymer precursor containing a monomer having a group that can be converted into an ion exchange group or an ion exchange group;
(2) a step of supplying a resin film continuously on both sides of a precursor-impregnated sheet obtained by impregnating the porous base material with a polymer precursor, and roll laminating the precursor-impregnated sheet between the resin films; And
(3) a polymerization step of polymerizing the polymer precursor to form a polymer;
2. To prevent the polymer precursor from adhering to the laminating roller, (a) the width of the upper and lower rollers of the roll laminate is made larger than the width of the precursor-impregnated sheet, and (b) the width of the upper and lower resin films is increased. 1. It is carried out by making it larger than the width of the precursor-impregnated sheet and (c) making the width of the lower resin film larger than the width of the lower roller of the roll laminate. The continuous manufacturing method of the electrolyte membrane as described in any one of.
3. 1. Prevention of adhesion of the polymer precursor to the laminating roller is further performed by (d) making the width of the upper resin film larger than the width of the lower resin film. The continuous manufacturing method of the electrolyte membrane as described in any one of.

  According to the method for continuously producing an electrolyte membrane of the present invention, in the step of supplying a resin film on both sides of a precursor-impregnated sheet, roll laminating the precursor-impregnated sheet between the resin films, and polymerizing the polymer precursor The polymer precursor protruding from the film is prevented from adhering to the laminating roller, so that the electrolyte is filled in the pores of the porous substrate without interrupting the continuous process. A film can be obtained efficiently.

Hereinafter, the present invention will be described in detail.
(1) Impregnation step The porous substrate is a substrate that is formed when an electrolyte polymer is formed by forming an electrolyte polymer in the pores of the porous substrate, and is continuously conveyed. In this case, usually, a long sheet wound around a winding core is used, and the long sheet is continuously conveyed at a predetermined speed. Although a conveyance speed is not specifically limited, It can be set as 0.01-100 m / min, and it is preferable to set it as 1-50 m / min.
As the porous substrate, glass, silica, or an inorganic material such as alumina can be used, but it is preferable to use materials made of various resins from the viewpoint of ease of handling and price. The resin used for forming the porous substrate is not particularly limited. Polyolefin resins such as polyethylene and polypropylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride- Vinyl chloride resins such as olefin copolymers, polytetrafluoroethylene, polytrifluoroethylene, polychlorotrifluoroethylene, poly (tetrafluoroethylene-hexafluoropropylene), poly (tetrafluoroethylene-perfluoroalkyl ether), etc. And fluororesin, polyamide resin such as nylon 6 and nylon 66, aromatic polyimide, aramid, polysulfone, and polyetheretherketone. Of these, polyimide resins or polyolefin resins excellent in mechanical strength, chemical stability, chemical resistance and the like are preferable, and polyolefin resins modified by the following method are more preferable. Specifically, it is a porous base material that has been cross-linked by electron beam irradiation, chemical cross-linking with a cross-linking agent, etc., and has improved heat resistance, etc. A porous substrate is preferred. Furthermore, the porous base material which gave bridge | crosslinking and extending | stretching etc. together is more preferable.

The porosity of the porous substrate is 5 to 95%, more preferably 5 to 90%, and particularly preferably 20 to 80%, although it depends on the type of filled polymer and the product in which the porous substrate is used. . Although the preferable range of the average pore diameter varies depending on the kind of the filled polymer, the product in which the porous substrate is used, and the like, it is preferably 0.001 to 100 μm, particularly preferably 0.01 to 1 μm. Further, the porosity of the porous substrate is 5 to 95%, further 5 to 90%, particularly 20 to 80%, and the average pore diameter is 0.001 to 100 μm, particularly 0.01 to 1 μm. Is more preferable. When the porous substrate is used, for example, for an electrolyte membrane of a fuel cell, if the porosity is too small, the number of ion exchange groups per area becomes too small and the output decreases. On the other hand, when the porosity is too large, the strength is undesirably lowered. Further, the thickness of the porous substrate also depends on the type of the filled polymer and the product in which the porous substrate is used, but is preferably 200 μm or less, preferably 1 to 150 μm, more preferably 5 to 100 μm, particularly 5 to 50 μm. It is more preferable. If the porous substrate is too thin, the strength is lowered. For example, when it is used as an electrolyte membrane for a fuel cell, the amount of hydrogen or methanol crossover is increased, which is not preferable. On the other hand, it is not necessary to increase the thickness beyond 200 μm. For example, in the case of a fuel cell, if it is too thick, the membrane resistance becomes excessive and the output decreases, which is not preferable.
The variation in the thickness of the porous substrate is preferably ± 5% or less, more preferably ± 1% or less.

  The tensile elastic modulus of the porous substrate is preferably 500 to 5000 MPa, particularly 1000 to 5000 MPa. The tensile strength at break of the porous substrate is preferably 50 to 500 MPa, particularly 100 to 500 MPa. Furthermore, it is more preferable that the tensile modulus of the porous substrate is 500 to 5000 MPa, particularly 1000 to 5000 MPa, and the tensile strength at break is 50 to 500 MPa, particularly 100 to 500 MPa. If the tensile elastic modulus of the porous substrate is at least one of 500 to 5000 MPa and the tensile breaking strength is 50 to 500 MPa, the porous substrate has an appropriate rigidity, for example, at the time of electrode bonding when used as an electrolyte membrane of a fuel cell. Cracking does not occur due to pressure forming of the battery and tightening during battery assembly. Although the fuel cell is heated during operation, it is preferably a porous substrate that has sufficient heat resistance at this temperature and does not easily deform even when an external force is applied.

  The polymer precursor contains an ion exchangeable monomer, that is, a monomer having an ion exchange group or a group that can be converted into an ion exchange group. Various monomers can be used as the ion exchange capacity monomer depending on the purpose and application of the electrolyte membrane, for example, for fuel cells or for electrolysis.

  As a monomer having an ion exchange group used for an electrolyte membrane for uses such as a fuel cell, a monomer having a proton acidic group that is excellent in performance when used as an electrolyte membrane for a fuel cell is preferable. The monomer having a proton acidic group is a compound having a polymerizable functional group and a protonic acid in one molecule, such as 2- (meth) acrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid, (meth) Examples include allyl sulfonic acid, vinyl sulfonic acid, isoprene sulfonic acid, (meth) acrylic acid, maleic acid, crotonic acid, vinyl phosphonic acid, acidic phosphoric acid group-containing (meth) acrylate and the like. These monomers having an ion exchange group may be used alone or in combination of two or more. “(Meth) acryl” means “acryl and / or methacryl”, “(meth) allyl” means “allyl and / or methallyl”, and “(meth) acrylate” means “acrylate and / or methacrylate”. (The same applies to the following).

A monomer having a group that can be converted into an ion exchange group can also be used. Examples of this monomer include salts, anhydrides and esters of the above compounds. When the acid residue of the monomer used is a derivative such as a salt, an anhydride, or an ester, proton conductivity can be imparted by making it into a protonic acid type after polymerization. Furthermore, a monomer having a site capable of introducing an ion exchange group after polymerization can also be used. Examples of this monomer include monomers having a benzene ring such as styrene, α-methylstyrene, chloromethylstyrene, and t-butylstyrene. Examples of the method for introducing an ion exchange group into these monomers include a method of sulfonation with a sulfonating agent such as chlorosulfonic acid, concentrated sulfuric acid, sulfur trioxide and the like. These monomers may use only 1 type and may use 2 or more types.
As the monomer having a protonic acid group, a vinyl compound having a sulfonic acid group having excellent proton conductivity or a vinyl compound having a phosphoric acid group is preferable, and 2- (meth) acrylamide-2-methylpropanesulfonic acid having high polymerizability is preferable. Is particularly preferred.

  Monomers having ion exchange groups used for electrolyte membranes for electrolysis and the like include 2- (meth) acrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid, (meth) allylsulfonic acid, vinylsulfonic acid, maleic Examples thereof include monomers having a protonic acid group such as acid and crotonic acid, and basic monomers such as vinylpyridine and p-vinyl-N, N-dimethylbenzylamine. These monomers may use only 1 type and may use 2 or more types.

The polymer precursor may be composed only of an ion exchangeable monomer and contains an ion exchangeable monomer and another monomer copolymerizable with this monomer (hereinafter referred to as “other monomer”). Also good. Furthermore, the polymer precursor may contain an ion exchangeable monomer and a crosslinkable monomer, and may contain an ion exchangeable monomer, another monomer, and a crosslinkable monomer.
In the case of an ion exchange ability monomer used for an electrolyte membrane for uses such as a fuel cell, a monomer having no proton acidic group can be contained as the other monomer. The other monomer is not particularly limited as long as it is a monomer copolymerizable with a monomer having an ion exchange group and a crosslinkable monomer, and is not limited to (meth) acrylic acid esters, (meth) acrylamides, maleimides, Examples include styrenes, organic acid vinyls, allyl compounds, and methallyl compounds. These monomers may use only 1 type and may use 2 or more types.

  Furthermore, in the case of an ion exchangeable monomer used for an electrolyte membrane for applications such as electrolysis, as other monomers, a monomer having no ion exchange group, a crosslinkable monomer, etc. for strength improvement, hydrophilicity adjustment, etc. Can be contained. These monomers may use only 1 type and may use 2 or more types.

Furthermore, as the crosslinkable monomer, a monomer having two or more polymerizable functional groups in one molecule can be used. Examples of the crosslinkable monomer include N, N′-methylenebis (meth) acrylamide, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane diallyl ether, pentaerythritol triallyl ether, and divinylbenzene. Bisphenol di (meth) acrylate, isocyanuric acid di (meth) acrylate, tetraallyloxyethane, triallylamine, diallyloxyacetate and the like. In addition, the crosslinkable monomer is not limited to one having a carbon-carbon double bond, and a bifunctional or higher functional epoxy compound can be used although the reaction rate is slightly low. When this epoxy compound is used, a cross-linking bond is formed by reacting with a carboxyl group of the polymer. Only one type of crosslinkable monomer may be used, or two or more types may be used.
In addition, the porous substrate can be impregnated with various components other than the polymer precursor such as a polymerization initiator, an antioxidant, an ultraviolet absorber, and a colorant, if necessary.

In the present invention, the impregnation of the polymer precursor or the like can be performed by impregnating the polymer precursor or the like into the pores of the porous substrate. The impregnation method is not particularly limited, and a method of immersing the porous substrate in a polymer precursor or the like or a solution or dispersion obtained by dissolving or dispersing the polymer precursor or the like in a solvent, or a polymer precursor or the polymer precursor Examples thereof include a method of spraying a solution or dispersion obtained by dissolving or dispersing a body or the like in a solvent onto a porous substrate. The former method is preferred as the impregnation method. With this method, the polymer precursor or the like can be uniformly impregnated with the porous substrate. The polymer precursor or the like is particularly preferably uniformly impregnated in the pores of the porous substrate. For this purpose, the porosity of the porous substrate and the average pore diameter of the pores, and the polymer precursor or the like It is preferable to select a method for impregnation while considering the viscosity of the solution and the like, and to set conditions for the impregnation.
The impregnation of the polymer precursor or the like can be performed by impregnating the polymer precursor or the like into the pores of the long porous substrate that is continuously conveyed.

  The temperature, time, etc. during the impregnation are not particularly limited, but the temperature is preferably 0 to 120 ° C, more preferably 5 to 80 ° C, and particularly preferably 5 to 50 ° C. The time is preferably 0.1 second to 1 hour, more preferably 1 second to 10 minutes, and particularly preferably 1 second to 5 minutes. Further, the temperature is 0 to 120 ° C., further 5 to 80 ° C., particularly 5 to 50 ° C., and the time is 0.1 second to 1 hour, further 1 second to 10 minutes, particularly 1 second to 5 minutes. It is more preferable.

Each component such as a polymer precursor can be impregnated as it is if it itself is a liquid, particularly a liquid having a viscosity that is low enough to be impregnated. The preferable viscosity in this case is 1 to 10000 mPa · s. Furthermore, when impregnation cannot be carried out as it is, each component, such as a polymer precursor, can also be impregnated with a solution or dispersion in which each component is dissolved or dispersed in a solvent.
The viscosity of this solution or dispersion is also preferably 1 to 10,000 mPa · s.
Moreover, when using various components, such as a polymerization initiator, these can each be impregnated separately from a polymer precursor. Furthermore, at least one of polymerization initiators and the polymer precursor can be mixed and impregnated simultaneously. Also, all of the polymerization initiator and the like can be mixed with the polymer precursor and impregnated simultaneously.
Further, when impregnated as a solution or dispersion, they can be impregnated as a solution or dispersion, respectively, separate from the polymer precursor. Moreover, it is also possible to impregnate each component simultaneously using a solution or dispersion containing at least one of polymerization initiators and the like and a polymer precursor. Furthermore, it is possible to impregnate each component simultaneously using a solution or dispersion containing all of the polymerization initiator and the like and the polymer precursor.
As described above, if at least one of the polymerization initiators, preferably all the components such as the polymerization initiator, and the polymer precursor are impregnated simultaneously, each component is introduced into the pores of the porous substrate. It can be impregnated uniformly.

(2) Roll laminating step In this step, the first and second resin films are supplied to and brought into contact with both surfaces of the precursor-impregnated sheet impregnated with the polymer precursor, and the precursor-impregnated sheet is divided into two resin films. And laminating by applying pressure between two rollers positioned outside the two resin films.
This process is continuously performed by smoothly transporting the porous substrate or the like at a predetermined speed. If the impregnated polymer precursor does not fall off before polymerization, the polymer is sufficiently filled in the pores from the surface to the inside, and an electrolyte membrane free from defects can be obtained. Moreover, it is preferable that the resin film and the precursor impregnated sheet are in close contact so that a gas such as air does not enter each interface. Thus, if intrusion of air or the like is prevented, polymerization is not inhibited particularly when a radical polymerizable polymer precursor is used, and the electrolyte membrane can be manufactured more efficiently.

When manufacturing continuously, the 1st resin film and the 2nd resin film can be continuously sent out from a film supply source, respectively, can be supplied, and can be made to contact with a precursor impregnation sheet.
As the film supply source, a long film wound around a winding core is usually used, and the first and second resin films fed and supplied from the film supply source are respectively precursor-impregnated sheets. The precursor-impregnated sheet is brought into contact with one surface and the other surface and conveyed while being sandwiched between two resin films. Further, the precursor-impregnated sheet or the like is conveyed in the horizontal direction, but this conveyance direction may be inclined or conveyed in the vertical direction. Furthermore, it may be conveyed from below to above or from above to below.
However, in order to prevent the necessary polymer precursor filled in the pores from overflowing from between the resin films, it is preferable that the roll laminate is transported in the horizontal direction or with a weak inclination.
In addition, after superposition | polymerization, the 1st and 2nd resin film can be made to peel from a precursor impregnation sheet | seat, respectively, and can be wound and stored on a winding core. Each resin film wound around the core can be reused until it becomes unusable due to fouling, wrinkles, elongation, or the like.

The resin forming the first and second resin films is not particularly limited. Furthermore, the first and second resin films may be made of the same kind of resin or may be made of different resins. The resin may be a thermoplastic resin or a thermosetting resin, but a thermoplastic resin capable of easily forming a film having a high strength is preferable. Examples of the thermoplastic resin include polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyolefins such as polyethylene and polypropylene, polyamides such as nylon 6 and nylon 66, polyvinyl chloride, cellulose, polycarbonate, and polyphenylene sulfide. Among these thermoplastic resins, there are polyesters and polyolefins which are not easily altered by the impregnated compounds and the like, irradiation of active energy rays such as ultraviolet rays and electron beams, overheating at the time of thermal polymerization, and the film is not easily deformed. preferable. Moreover, the film which consists of polyester and polyolefin is preferable also at the point of being easy to permeate | transmit an active energy ray, when polymerizing by irradiation of an active energy ray. The polyester is more preferably polyethylene terephthalate, and the polyolefin is more preferably polypropylene.
Here, the same type of resin means that the main repeating unit constituting the molecule (for example, when the total repeating unit is 100 mol%, the main repeating unit is 80 mol% or more) is from the same monomer. It may have a repeating unit consisting of a small amount of other monomers, and the molecular weight, crystallinity, etc. may be different.

  Moreover, when it superposes | polymerizes by irradiating an active energy ray, it is preferable to use a film transparent to an active energy ray which an active energy ray permeate | transmits as a 1st resin film and a 2nd resin film. The transmissivity of this active energy ray [(dose after passing through the film / dose applied to the film) × 100 (%)] is preferably 5% or more, particularly preferably 30% or more. Furthermore, when using ultraviolet light and visible light, it is preferably colorless and transparent, and may be colored and transparent, but is transparent or at least transparent in the wavelength region where the polymerization initiation function of the polymerization initiator is expressed. Is preferably high. Further, when an electron beam is used, it may be opaque by visual observation, but it is preferable that it is transparent or at least highly transparent because the appearance and the like can be confirmed through a film during polymerization or the like.

  The thickness of the first and second resin films is not particularly limited. Moreover, the thickness of the 1st and 2nd resin film may be the same, and may differ. The thickness of the first and second resin films is preferably 3 to 100 μm, more preferably 5 to 80 μm, and particularly preferably 7 to 60 μm. If the thickness of each film is less than 3 μm, wrinkles are easily generated, and the precursor-impregnated sheet cannot be sufficiently supported during polymerization, which is not preferable. On the other hand, when the thickness exceeds 100 μm, it is not preferable because the active energy dose to be used increases because it is absorbed by the film when using active energy rays for polymerization.

Furthermore, when using an active energy ray for superposition | polymerization, it is preferable that the thickness of each of the 1st and 2nd resin film differs, and one is thin and the other is thick. By irradiating active energy rays from the thin resin film side with different thicknesses as described above, the active energy dose absorbed by the resin film can be reduced, and the polymerization can be sufficiently performed with a small active energy dose. . On the other hand, the precursor-impregnated sheet can be supported by a thick resin film. The thickness of the thin resin film is preferably 1/10 to 1/2 of the thickness of the thick resin film, more preferably 1/8 to 1/3, and particularly preferably 1/6 to 1/4. Moreover, it is preferable that the thickness of a thin resin film is 3-30 micrometers, especially 5-20 micrometers, and also 7-15 micrometers. If the thickness of the thin resin film is 3 to 30 μm, the polymer precursor can be efficiently polymerized. On the other hand, the thickness of the thick resin film is preferably 35 to 80 μm, more preferably 40 to 65 μm, and particularly preferably 45 to 55 μm. If the thickness of the thick resin film is 35 to 80 μm, the precursor-impregnated sheet can be reliably supported.
The variation in thickness of each of the first and second resin films is preferably ± 10% or less, more preferably ± 2% or less.

  The first and second resin films may be brought into contact with the precursor-impregnated sheet as long as they can be easily peeled off from the sheet filled with the polymer after polymerization of the polymer precursor, but at least the precursor-impregnated sheet A release agent may be applied to the surface in contact with the substrate and processed. As this release agent, various types such as a silicon release agent, a fluorine release agent, and a higher aliphatic release agent can be used. Thus, by processing with a mold release agent, after superposition | polymerization, a 1st and 2nd resin film and a polymer filling sheet can be peeled rapidly, and a precursor impregnation sheet | seat etc. can be conveyed smoothly. .

  In the present invention, when the precursor-impregnated sheet is sandwiched between resin films, it is laminated by applying pressure with a roller simultaneously or after sandwiching. If the pressure at this time is too strong, the amount of the polymer precursor that protrudes between the two resin films will increase and the possibility of contaminating the roller will increase, as well as filling the pores as well as the surface of the precursor-impregnated sheet Since the polymer precursor thus prepared is handled and the electrolytic mass in the pores is reduced, the performance of the final electrolyte membrane may be deteriorated. On the other hand, when the pressure is low, the laminate becomes insufficient, air enters between the precursor-impregnated sheet and the resin sheet, or the thickness of the laminate becomes non-uniform. There is a risk of uneven polymerization.

The present invention is characterized in that, in this step, the polymer precursor protruding from between the resin films is prevented from adhering to the laminating roller. Examples of this means include the following.
(I) (a) The width of the upper and lower rollers of the roll laminate is larger than the width of the precursor-impregnated sheet, (b) The width of the upper and lower resin films is larger than the width of the precursor-impregnated sheet, (C) The width of the lower resin film is made larger than the width of the lower roller of the roll laminate.
When the precursor-impregnated sheet is sandwiched between two resin films from above and below, by making the width of the lower resin film larger than the width of the lower roller of the roll laminate, It flows down along the upper surface of the resin film at a position outside the lower roller, and can be prevented from adhering to the lower roller.
The reason why the widths of the upper and lower rollers of the roll laminate and the widths of the upper and lower resin films are made larger than the width of the precursor-impregnated sheet is to enable roll lamination over the entire surface of the precursor-impregnated sheet. .
(Ii) In addition to (1), (d) the width of the upper resin film is made larger than the width of the lower resin film.
As a result, the polymer precursor flowing out from the precursor-impregnated sheet along the lower surface of the upper resin film flows down at a position away from the opposed lower resin film, that is, at a position outside the lower resin film roller. Also, it can be prevented from adhering to the upper roller.
There is no.
(Iii) In addition to this, there is a method in which the roller pressure is adjusted so that the excess polymer precursor does not flow out but remains on the surface of the precursor-impregnated sheet. The polymer precursor remaining on the surface can be removed in a polymer removal step described later.

(3) Polymerization process The method for polymerizing the polymer precursor impregnated in the precursor-impregnated sheet is not particularly limited. As described above, polymerization and heating by irradiation with active energy rays such as ultraviolet rays, electron beams, and visible rays. It can be carried out by thermal polymerization or the like. Among these methods, polymerization by irradiation with active energy rays is preferable. According to this method, the electrolyte membrane can be easily and efficiently continuously produced. Moreover, as an active energy ray, an ultraviolet ray and an electron beam are more preferable. When ultraviolet rays are used, the apparatus is simpler than an electron beam, which is advantageous in terms of irradiation cost. On the other hand, when an electron beam is used, it is easy to bond with the porous substrate, which is preferable. Furthermore, the electron beam is excellent in permeability to the porous substrate. In particular, when the porous substrate is made of a hydrocarbon-based polymer, a crosslinked structure can be introduced into the polymer depending on irradiation conditions. Polymerization by electron beam irradiation is also preferable in that a radical photopolymerization initiator or the like is not required.

  When polymerizing the polymer precursor by irradiating with ultraviolet rays, it is preferable to attach a radical photopolymerization initiator that generates radicals by ultraviolet rays in advance to the surface of the pores of the porous substrate. The radical photopolymerization initiator is preferably attached by impregnating the solution or dispersion containing the initiator into the pores of the porous substrate and then removing the solvent. In this way, the initiator can be uniformly deposited in the pores of the porous substrate.

The radical photopolymerization initiator is not particularly limited, but an aromatic ketone radical polymerization initiator capable of generating a radical by extracting hydrogen from a carbon-hydrogen bond such as benzophenone, thioxanthone, or thioacridone is preferable.
Examples of the benzophenone initiator include methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone. 2,4,6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxy-2-propenyloxy) ethyl] benzenemethananium bromide, (4-benzoylbenzyl) trimethyl Ammonium chloride, 4,4′-dimethylaminobenzophenone, 4,4′-diethylaminobenzophenone and the like can be mentioned. Examples of the thioxanthone initiator include thioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, and 2-ethylthioxanthone. Furthermore, examples of the thioacridone initiator include thioacridone.

As the radical photopolymerization initiator, benzoin-based initiators, acetophenone-based initiators, benzyl-based initiators, and the like can also be used.
Examples of the benzoin initiator include benzoin, benzoin methyl ether, benzoin isopropyl ether, benzoin ethyl ether, and benzoin isobutyl ether. Examples of the acetophenone-based initiator include acetophenone, propiophenone, diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- ( 4- (Methylthio) phenyl) -2-monforinopropane-1, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-hydroxy-2-methyl-1-phenyl And propan-1-one, 1- (4- (2-hydroxyethoxy) -phenyl) -2-hydroxydi-2-methyl-1-propan-1-one, and the like. Furthermore, examples of the benzyl initiator include benzyl.
Only one type of radical photopolymerization initiator may be used, or two or more types may be used.

  The radical photopolymerization initiator is preferably used as a solution or dispersion as described above. The concentration of the initiator in this solution or dispersion is preferably 0.01 to 10% by mass, particularly 0.1 to 5% by mass. When this concentration is less than 0.01% by mass, polymerization may not be sufficiently performed. On the other hand, if it exceeds 10 mass%, crystals of the initiator may precipitate and block some of the pores of the porous substrate. If some of the pores are blocked as described above, the polymer precursor or the like may not be sufficiently filled. Moreover, it may not be filled uniformly over the entire porous substrate, which is not preferable anyway.

When polymerizing a polymer precursor by irradiating with an electron beam, the accelerating voltage of the irradiated electron beam depends on the type of the polymer precursor and the like, but is preferably 150 to 500 KeV, particularly 150 to 200 KeV. If the acceleration voltage is too low, it is difficult to generate an electron beam, and if it is too high, the porous substrate may deteriorate and the strength may decrease. The irradiation amount also depends on the type of polymer precursor, but is preferably 1 to 600 Mrad, particularly 2 to 200 Mrad, and more preferably 2 to 100 Mrad. When the irradiation amount is less than 10 mJ / cm ² , the polymerization cannot be sufficiently performed, and when it exceeds 10000 mJ / cm ² , the porous substrate is deteriorated and the strength is lowered, which is not preferable.

  After polymerization by irradiation with an electron beam, it can be post-cured by heating or irradiation with ultraviolet rays, if necessary. The polymerization initiator for that purpose can also be previously blended with the polymer precursor. Examples of the polymerization initiator include azo compounds such as 2,2′-azobis (2-amidinopropane) dihydrochloride, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide. , Peroxides such as di-t-butyl peroxide, redox initiators combining the above peroxides with reducing agents such as sulfites, bisulfites, thiosulfates, formamidinesulfinic acid, ascorbic acid, Azo radical polymerization initiators such as 2,2'-azobis- (2-amidinopropane) dihydrochloride and azobiscyanovaleric acid. These polymerization initiators may use only 1 type and may use 2 or more types.

  As a post-curing method, curing by irradiation with ultraviolet rays is preferable because the polymerization reaction is easily controlled and a desired functional film can be obtained with a simple process and high productivity. In addition, when post-curing by irradiation with ultraviolet rays, it is more preferable to previously dissolve or disperse the radical photopolymerization initiator in a solution or dispersion containing the polymer precursor. As the radical photopolymerization initiator, those described above can be used. Furthermore, the blending amount of the radical photopolymerization initiator is 0.001 to 1% by mass, further 0.001 to 0.5% by mass, particularly 0.01 to 0.001% when the polymer precursor is 100% by mass. It is preferably 0.5% by mass.

During post-curing, the first and second resin films may be kept in contact with the precursor-impregnated sheet. Further, at least one of the first and second resin films may be peeled off as long as the polymerization proceeds to such a degree that the polymer precursor is sufficiently retained in the pores of the porous substrate. On the other hand, when the resin film is peeled off, excess polymer precursor attached to the surface of the porous substrate comes into contact with air and polymerization is suppressed, and it is more easily removed in the subsequent polymer removal step. can do.
(4) Polymer removal process

  If desired, a step of removing the polymer adhering to the surface of the polymer-filled sheet by a method such as scraping with a plastic blade made of polypropylene or the like can be added. Moreover, it can also remove by making an adhesion polymer removal tool contact a polymer filling sheet. This adhered polymer removing tool may be any one as long as the electrolyte membrane is not scratched and damage such as deformation does not occur. Examples of the attached polymer removing tool include a brush roll and a rubber blade. Furthermore, the polymer adhering to the surface can also be removed by passing the polymer-filled sheet through a narrow gap slightly wider than its thickness.

  It is also possible to remove the polymer adhering to the surface of the polymer-filled sheet by swelling with a liquid. The “liquid” is not particularly limited, and a swellable liquid that can be swollen to such an extent that the polymer can be easily removed can be used. Further, from the viewpoint of productivity, a short time contact, for example, a polymer-filled sheet is produced by continuously supplying a long porous base material, and the polymer adhering to the surface of the polymer-filled sheet and the swellability The liquid is preferably a liquid that can sufficiently swell the polymer when brought into contact with the liquid.

  The swellable liquid can be selected from water or various organic solvents depending on the type of polymer. In the case of a polymer that swells in water, such as a hydrophilic polymer or a polymer in which a cross-linked structure is introduced into a water-soluble polymer, an organic solvent compatible with water, such as water, methanol, ethanol, or the like as a swellable liquid, or these organic solvents A mixed solvent of water and water can be used.

  The impregnation step, the lamination step, the polymerization step, and the optional polymer removal step are performed continuously. In this continuous production method, a long porous base material is continuously conveyed and impregnated with a polymer precursor or the like to form a precursor-impregnated sheet, and then one surface and the other surface of the precursor-impregnated sheet are formed. The first and second resin films are continuously fed to and contacted with each other, and roll lamination is performed in such a state that the precursor-impregnated sheet is sandwiched between the first and second resin films. Polymerization of the precursor is performed to form a polymer-filled sheet, and then the first and second resin films are peeled from the polymer-filled sheet, and then the polymer attached to the surface of the polymer-filled sheet is removed. In this way, a series of operations are performed by a continuous process. Further, the obtained long electrolyte membrane can be stored as a product by a method such as continuous winding around a winding core.

This continuous manufacturing method can be performed, for example, by a process as shown in FIG. That is, the continuous porous substrate 1 that is continuously conveyed is brought into contact with a solution or dispersion 3 containing a polymer precursor or the like placed in a container (impregnation step), and then the polymer precursor or the like. Is impregnated, and the precursor impregnated sheet 11 obtained is brought into contact with the first resin film 21 and the second resin film 22 continuously supplied from the resin film supply sources 211 and 221, so that the precursor impregnated sheet is It is conveyed in a state of being sandwiched between two resin films and roll-laminated (laminating step). Next, the polymer precursor is polymerized by irradiating an electromagnetic wave having a wavelength of 300 to 400 nm from the electromagnetic wave irradiation source E (polymerization step), and then the first and second resin films are filled with the polymer in the porous resin sheet. Then, the polymer is peeled off from the attached polymer-filled sheet, and then the polymer attached to the surface of the polymer-filled sheet 12 is removed by scraping with the plastic blade 4 (polymer removal step), and then scraped with water sprayed from the nozzle N. The taken polymer is washed away, and then dried by a drying apparatus H as necessary, and the obtained functional film 5 can be continuously wound around a winding core for efficient production. Furthermore, in order to protect the product, it is possible to wind up while laminating a protective film 6 made of polyester, polyolefin, fluororesin or the like on at least one side (both sides in FIG. 1) of the functional film to be wound.
Other processes other than the impregnation process, the lamination process, the polymerization process, and the polymer removal process include a drying process after the polymer removal process, an inspection process after the drying process, a humidity control process, and the like. These other steps are also carried out as a continuous series of steps.

  The electrolyte membrane produced by the method of the present invention is useful as an electrolyte membrane in a polymer electrolyte fuel cell, particularly a direct methanol fuel cell. Thus, when using an electrolyte membrane in a fuel cell, the electrolyte membrane electrode assembly is sandwiched between two electrodes provided with a catalyst such as platinum and then integrated by a heating press or the like. Then, the assembly can be used by being incorporated in a fuel cell.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
Comparative Example 1
As a polymer precursor, 450 g of 2-acrylamido-2-methylpropanesulfonic acid, 50 g of N, N′-methylenebisacrylamide, 5 g of a nonionic surfactant, an ultraviolet radical polymerization initiator (trade name “Darocur 1173 manufactured by Ciba Specialty Chemicals Co., Ltd.) ]) A polymer precursor solution consisting of 0.5 g and 500 g of water was prepared.
As shown in FIG. 2, a porous polyethylene porous substrate (thickness 16 mm, porosity 40%, average pore diameter approximately 0.1 μm, substrate width 10 cm) is immersed in a container containing the above solution. Then, a porous substrate was impregnated with a polymer precursor or the like to prepare a precursor-impregnated sheet. Subsequently, the two polymer terephthalate films having a thickness of 50 μm and a width of 20 cm were sandwiched between both surfaces of the precursor-impregnated sheet by a laminating apparatus having an upper and lower roll width of 56 cm, and the polymer precursor solution was squeezed out. Next, ultraviolet rays were irradiated on both sides of the polyethylene terephthalate film using a high-pressure mercury lamp on each side 7 mW / cm ² × 60 seconds to polymerize the polymer precursor. Thereafter, the polyethylene terephthalate film was peeled from both sides to obtain an electrolyte membrane.
The excess polymer precursor squeezed out adheres to both laminate rolls and cannot be used immediately after the start of the experiment.

Example 1
The same polymer precursor solution as in Comparative Example 1 was used. As shown in FIG. 3, a porous polyethylene porous substrate (thickness: 16 mm, porosity: 40%, average pore diameter: about 0.1 μm, substrate width: 10 cm) is immersed in a container containing the above solution and porous. The precursor substrate was impregnated with a polymer precursor or the like to prepare a precursor-impregnated sheet. Next, two polyethylene terephthalate films having a thickness of 50 μm, a width of 20 cm and a width of 15 cm were stacked on both sides of the precursor-impregnated sheet, and sandwiched by a laminating apparatus having an upper roll width of 56 cm and a lower roll width of 13 cm to squeeze out the polymer precursor solution. . Next, ultraviolet rays were irradiated on both sides of the polyethylene terephthalate film using a high-pressure mercury lamp on each side 7 mW / cm ² × 60 seconds to polymerize the polymer precursor. Thereafter, the polyethylene terephthalate film was peeled from both sides to obtain an electrolyte membrane.
The surplus polymer precursor did not adhere to the laminating roll, and the electrolyte membrane could be produced continuously.

  The electrolyte membrane of the present invention can be applied not only to fuel cells, but also to electrochemical device elements such as various sensors and separation membranes for electrolysis.

It is a flowchart which shows an example of the process for manufacturing an electrolyte membrane. In comparative example 1, it is a mimetic diagram showing the state where the surplus polymer precursor squeezed out by the roll lamination process adhered to both lamination rollers. In Example 1, it is a schematic diagram which shows the state in which the excess polymer precursor squeezed out by the roll lamination process does not adhere to both lamination rollers.

Explanation of symbols

1 Porous substrate (Polyethylene porous substrate)
DESCRIPTION OF SYMBOLS 11 Precursor impregnated sheet 12 Polymer filled sheet 21 1st resin film 22 2nd resin film 211, 221 Film supply source 3 Solution or dispersion containing polymer precursor etc. E Irradiation source of active energy rays 4 Plastic blade N Nozzle for spraying water for washing H Drying device 5 Functional film 6 Protective film 7 Upper resin film 8 Lower resin film 9 Upper laminating roller 10 Lower laminating roller 13 Excess polymer precursor

Claims (2)

In the method for producing an electrolyte membrane having at least the following steps (1) to (3), the step (2) includes: (a) the widths of the upper and lower rollers of the roll laminate are made larger than the width of the precursor-impregnated sheet. (B) The width of the upper and lower resin films is made larger than the width of the precursor-impregnated sheet, and (c) the width of the lower resin film is made larger than the width of the lower roller of the roll laminate. A method for continuously producing an electrolyte membrane, which is carried out while preventing sticking of the polymer precursor protruding from the laminating roller.
(1) an impregnation step of continuously conveying a porous substrate and impregnating the porous substrate with a polymer precursor containing a monomer having a group that can be converted into an ion exchange group or an ion exchange group;
(2) a step of supplying a resin film continuously on both sides of a precursor-impregnated sheet obtained by impregnating the porous base material with a polymer precursor, and roll laminating the precursor-impregnated sheet between the resin films; And
(3) A polymerization step of polymerizing the polymer precursor to produce a polymer.
2. The electrolyte according to claim 1 , wherein the prevention of adhesion of the polymer precursor to the laminating roller is further performed by (d) making the width of the upper resin film larger than the width of the lower resin film. A continuous production method of a membrane.

Images