JPH09156007A - Moistening film and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide superior properties such as resistance to heat and resistance to chemicals in addition to water repellency, volatility and stain resistance by coating the skeleton of a porous polymer base with a tetrafluoroethylene copolymer and forming open-pares. SOLUTION: The skeleton of a porous base can be coated with a tetrafluoroethylene copolymer by melting tetrafluoroethylene copolymer particles remaining in an internal structure forming the porous polymer base. When the skeleton of the porous polymer base is coated with the tetrafluoroethylene copolymer, the adjustment for keeping an open-pore structure of a porous polymer material as a base is carried out. A moistening film is of sheet shape and can be used for various forma of use. The peripheral edges of a moistening sheet 11 are sealed, and a water injection opening 13 is provided close to one end.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a humidifying membrane for a humidifier and a method for manufacturing the humidifying membrane.

[0002]

2. Description of the Related Art Humidifiers are generally used as a means of controlling humidity in a living space. As the humidifier, various types such as an ultrasonic system, a spray system, and a natural evaporation system have been put into practical use, but because of low running cost, cleanliness without generation of white powder, etc.,
Membrane-type humidifiers using hydrophobic polymer porous membranes have recently attracted attention. This utilizes the property of a hydrophobic polymer porous membrane that water vapor is permeable but water is not permeable. With this porous membrane as a boundary surface, water is provided in one region and the other region is provided. By sending air to, the water vapor is moved through this porous membrane to humidify the air side. This membrane humidifier is disclosed in JP-A-50-588.
52, Japanese Utility Model Laid-Open No. 54-56963, and Japanese Patent Laid-Open No. 6
No. 0-171337 and Japanese Patent Laid-Open No. 61-27434 disclose specific examples.

[0003]

However, the humidifier using the humidifying film made of the above hydrophobic porous material has a problem that when the humidifying water is mixed with an oily component such as cutting oil used in plumbing work, etc. After the components adhere to the surface of the membrane, they penetrate into the inside of the membrane, and the humidifying water permeates the membrane and leaks from the invading portion. Also, due to long-term use,
Organic and inorganic impurities contained in the humidifying water adhere to the surface of the humidifying film, and the dirt reduces the water repellency of the humidifying film, making it impossible to maintain the prescribed water pressure resistance and causing the humidifying water to leak. become. Such a leak of water from the humidifier causes water droplets to be mixed with the humidified air and leak inside the room. At the same time, the humidifying water containing components such as calcium scatters indoors, and when the scattered water dries, white powder remains behind, resulting in white powder pollution.

As described above, the conventional humidifying film is resistant to cutting oil,
Due to lack of stain resistance and the like, when operating a humidifier using such a humidifying membrane, it was necessary to pretreat the humidifying water to remove these impurities. However, it was not practical due to the large scale and high cost. Therefore, when the contamination by the cutting oil and the contamination by the impurities in the humidifying water occur, it is necessary to replace the entire humidifying film.

In order to solve the above problems, Japanese Patent Application Laid-Open No. 5-18572 proposes to use a humidifying film in which a continuous film of a hydrophilic resin is provided on a porous hydrophobic polymer material. There is. However, this humidifying membrane is made of a non-porous porous material, and a decrease in moisture permeability is unavoidable.
The decrease in humidification capacity has led to an increase in the size of the device. Further, since this humidifying membrane is non-porous, it has no air permeability, and when introducing the humidifying water into the humidifier, a separate means for eliminating the air is required, which is troublesome.

From the above, it has been desired to develop a humidifying film having a stain resistance and a high moisture permeability. The Applicant has previously found that the skeleton of the porous polymer substrate is coated with an organic polymer having water repellency and oil repellency, preferably an organic polymer having a fluorinated organic side chain as a pendant group repeatedly appearing, and is continuous. With a humidifying membrane for humidifiers that has pores,
It has been disclosed that the above problems can be solved (Japanese Patent Application No. 06-237689).

On the other hand, since fluoropolymers containing tetrafluoroethylene are generally superior to other polymers in thermal stability, chemical resistance, etc., tetrafluoroethylene should be used for covering the pores of the above humidifying film for humidifiers. Is desirable. However, it is necessary to provide a microemulsion of tetrafluoroethylene to uniformly coat a porous substrate having pores less than 1 micron with tetrafluoroethylene to leave open pores.

An object of the present invention is to provide a humidifying membrane for a humidifier in which the skeleton of a porous substrate is coated with this tetrafluoroethylene.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made by discovering that the above object can be achieved by adopting an aqueous seeded microemulsion polymerization method using tetrafluoroethylene as a starting monomer. . The average diameter of the particles of this microemulsion is 1 to 100 nm (0.001 to 0.1 μm), preferably 1 to 80 nm
(0.001 to 0.08 μm), more preferably 5 to 50 nm (0.
001 to 0.05 μm).

Thus, according to the present invention, there is provided a humidifying membrane for a humidifier, characterized in that the skeleton of the porous polymer substrate is covered with a tetrafluoroethylene copolymer and has continuous pores. It According to another aspect of the present invention, a porous substrate is coated with an aqueous latex in which particles of the tetrafluoroethylene copolymer are present and which particles have an average particle size of 0.01 to 0.5 μm. Also provided is a method for producing a humidifying membrane for a humidifier, which comprises a step of subsequently removing water and a surfactant present, and then melting the polymer to coat the substrate skeleton.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The porous polymer base material used in the present invention is composed of a polymer material having a large number of fine pores communicating from the front surface to the back surface of the base material. Specifically, those having heat resistance and corrosion resistance are preferable, and porous bodies of polyolefin resin such as polyethylene and polypropylene, porous bodies such as polycarbonate, polystyrene, polyvinyl chloride, polyvinylidene chloride and polyester, polytetra A fluororesin porous material such as fluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer, polyvinyl fluoride, or polyvinylidene fluoride can be used. Among them, a porous material obtained by stretching polytetrafluoroethylene The material has a unique continuous porous structure composed of fibrils called fibrils and nodules called nodes, and it is possible to stably incorporate fine particles of the organic polymer used in the present invention into the structure. Excellent in water repellency, heat resistance and chemical resistance It can be said that the fee.

As the pore size of the porous polymer material, it is necessary for the particles of the organic polymer of the present invention to enter, and the average pore size of usually 0.01 to 10 μm, particularly 0.1 to 1 μm is preferable. If this pore size is too large, the water pressure resistance is lowered, which is not good. The porosity is preferably 5 to 95%, particularly preferably 60 to 95%. If the porosity is too small, the moisture permeability decreases and the humidification efficiency decreases. If it is too large, the strength of the porous material will decrease. About thickness 5
.About.1000 .mu.m, particularly 30 to 100 .mu.m is preferable. If it is too thick, the water vapor permeability decreases, and if it is too thin, there is a problem in strength.

The tetrafluoroethylene copolymer coating the skeleton of the porous polymer substrate of the present invention is not particularly limited as long as it is a copolymer containing tetrafluoroethylene.
Binary or ternary or more copolymer of tetrafluoroethylene and a monomer selected from acrylate, methacrylate, styrene, acrylonitrile, vinyl, allyl and alkene, particularly fluoroacrylate / tetrafluoroethylene copolymer, fluoroacrylate / Hexafluoropropylene / tetrafluoroethylene copolymer is preferred. Since this tetrafluoroethylene copolymer has hydrophobicity and oleophobicity, it has stain resistance, acts to increase the water repellency and oil repellency of the porous polymer material that is the base material, and has heat resistance, It has been found that not only is excellent in chemical resistance, but also the adhesiveness to a base material, particularly when porous PTFE is used as the base material, is strongly bonded to the base material.

The following can be mentioned as typical other monomers copolymerized with tetrafluoroethylene. Acrylate : Alkyl acrylate, fluoroalkyl acrylate, chloroalkyl acrylate, bromoalkyl acrylate, etc., having less than 25 carbon atoms.

Methacrylate : alkyl methacrylate, fluoroalkyl methacrylate, chloroalkyl methacrylate, bromoalkyl methacrylate, etc., having less than 25 carbon atoms. Styrene : Styrene, methylstyrene, fluorostyrene, chlorostyrene, bromostyrene, etc.

Acrylonitrile : Acrylonitrile, methacrylonitrile, etc. Vinyl : Vinyl acetate, vinylidene chloride, alkyl vinyl ether, fluoroalkyl vinyl ether, etc. Allyl compounds : allyl acetate, allyl chloride, allyl bromide, etc. Alkenes : hydrocarbons, fluorocarbons, chlorocarbons, bromocarbons with 4 to less than 20 carbon atoms,
For example, hexene, heptene, octene, decene, fluorohexene, fluoroheptene, fluorooctene,
Such as fluorodecene.

Specifically, Japanese Patent Application No. 06-23768 is previously mentioned.
All of the following fluoropolymers disclosed in No. 9 contain a copolymerizable unsaturated group and are suitable copolymerizable monomers. formula

[0018]

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## STR1 ## wherein n is a group number of ₃ to 13 and R is H or CH ₃ ; fluoroalkyl acrylates and fluoroalkyl methacrylates, fluoroalkylaryl urethanes such as

[0020]

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Fluoroalkylallyl urethanes, for example

[0022]

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Fluoroalkyl maleic acid esters, for example

[0024]

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Fluoroalkyl urethane acrylate,
Those obtained by polymerizing monomers such as fluoroalkylamides and fluoroalkylsulfoamide acrylates are preferable. The fluorinated alkyl moiety preferably has 6 to 16 carbon atoms, and most preferably 6 to 12 carbon atoms. Furthermore, as the monomer to be copolymerized, other than polytetrafluoroethylene,
Fluorine-containing monomers such as fluoroolefin and fluorovinyl ether, for example, perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, or perfluorovinyl ether having a functional group such as a carboxylic acid group or a sulfonic acid group, vinylidene fluoride, vinyl fluoride. , Ethylene trifluoride chloride, etc. can also be used.

In order to coat such a tetrafluoroethylene copolymer on a porous polymer substrate, it is necessary to prepare a microemulsion of the tetrafluoroethylene copolymer. This is made possible by the aqueous seeded microemulsion polymerization method, which comprises the following steps: (1) A microemulsion of a polymerizable unsaturated monomer liquid in water is formed as a seed; (2) A radical polymerization initiator is added to a seeded monomer microemulsion to initiate a polymerization reaction to radically polymerize; ) Tetrafluoroethylene, or tetrafluoroethylene and other monomers are introduced into the microemulsion system from the gas phase before or after the microemulsion polymerization in step (2).

Tetrafluoroethylene and other gaseous monomers participate in the polymerization to form small particles of polymer. The liquid polymerizable monomer used in the step (1) may be a liquid radical-polymerizable unsaturated organic monomer, and a fluorinated monomer is preferable. It forms an oil-in-water microemulsion at a polymerization temperature of 0 to 150 ° C, preferably 40 to 100 ° C. This liquid polymerizable monomer microemulsion has an average particle size of
1-100nm (0.001-0.1μm), preferably 1-80nm
(0.001 to 0.08 μm), most preferably 1 to 50 nm.

In step (2), when the gaseous monomer is introduced into the aqueous phase of the reactor prior to initiating the microemulsion polymerization, the final particles generally contain a random copolymer. On the other hand, when the gaseous monomer is introduced after polymerizing the liquid monomer from step (1), the gaseous monomer transferred from the gas phase to the aqueous phase polymerizes and deposits on the outer surface of the seeded polymer particles. To give a core / shell type grain structure. The core / shell type particles have 0.1-99% by weight polymer core and 1-99.9% by weight polymer shell, the shell comprising monomer units from the gas phase, preferably tetrafluoroethylene units.

In one aspect, the method includes the following steps. (A) Liquid polymerizable ethylenically unsaturated organic monomer in a water reactor at a ratio of monomer to surface boundary agent and temperature sufficient to spontaneously form a microemulsion in a pressure reactor; Then, a gaseous ethylenically unsaturated fluorinated organic monomer is introduced into the reactor (b), and a radical polymerization initiator is added to the reactor (c) to start the reaction of the monomers.

As one modification, step (c) is performed before step (b), and as another modification, step (b) is performed before step (c). The particles of the polymer obtained by the usual aqueous emulsion polymerization of fluorinated monomers have a particle size of 0.1 to 1
The particle size is about 0 μm, and it is difficult to uniformly coat a substrate having a submicron porous structure, but in the present invention, the organic polymer is a fine particle having an average particle size of 0.01 to 0.5 μm. By so doing, it is possible to well penetrate into the fine structure of the porous polymer material and form a coating having a uniform thickness on this skeletal structure.

The liquid monomer is preferably fluoroacrylate or fluoromethacrylate. The amount of the components used is 0.1 to 40% by weight of the monomer, preferably 0.1 to 20% by weight, and 0.1 to 40% by weight of the surfactant, preferably 0.1 to 40% by weight.
25% by weight, balance water. In order to initiate the polymerization of the seeded microemulsion, the temperature of the monomer microemulsion is 0 to 150 ° C., preferably 40 to 10 ° C.
Adjust to 0 ° C. The polymerization initiator is a water-soluble or oil-soluble free radical polymerization initiator, for example, a persulfate salt, an azo initiator, a peroxide, or a photoinitiator generated by UV or gamma ray activation. Initiation
Can also be used. The amount of initiator present can be 0.01 to 20% by weight, based on the liquid monomer content. Cosolvents such as alcohols, amines or other amphipathic molecules, or salts can also be used to facilitate the formation of microemulsions. The introduction of the initiator initiates the polymerization of the monomers.

The gaseous monomer can be introduced before or after the introduction of the initiator. If before, the liquid monomer will polymerize and the gaseous monomer and the resulting polymer product will contain many forms of particles. For example, the particles can include homopolymers of liquid monomers, or homopolymers of gaseous monomers, or random copolymers having these units, depending on the relative rate of polymerization of each monomer.

On the other hand, if the gaseous monomer is introduced after the polymerization of the liquid monomer has started, the polymerizable particles will be in the core / shell form. The core consists of a homopolymer of liquid monomer. If almost all of the liquid monomer is polymerized before adding the gaseous monomer, a shell of gaseous homopolymer forms around the core. However, when all the liquid monomers are not polymerized when the gaseous monomer is added, the copolymer of liquid and gaseous monomers forms a shell around the core.

Preferably, the gaseous monomer is an unsaturated monomer polymerizable by a radical polymerization initiator and contains at least tetrafluoroethylene, while the other gaseous monomer is olefin with or without halogen. it can. For example, vinyl fluoride, vinylidene fluoride, trifluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, perfluoroalkylethylene, chlorotrifluoroethylene, vinyl chloride, vinylidene chloride, ethylene, propylene, butylene and butadiene, or any of these. Is a combination of. The gaseous monomer is tetrafluoroethylene or a mixture containing it, but the monomer combined with tetrafluoroethylene is preferably fluorinated. Of course, the gaseous monomer will not be the same as the liquid monomer used.

Thorough mixing of the liquid and gas phases is important for promoting mass transfer. Polymerization temperature is 0 to 150
The temperature may be ℃, preferably 40 to 100 ℃. The polymerization is carried out in a pressure vessel, and the polymerization pressure is 200 to 200,000 kPa, preferably 200 to 20,000 kPa. The polymerization is carried out for 1 to 500 minutes, or at least until 50% or more of the liquid monomer is converted into a polymer. The amount of the gas phase monomer used can be determined by measuring the pressure in the reactor.

The latex of the polymer particles obtained has an average particle size of 1 to 100 nm, preferably 1 to 80 nm, most preferably 1 to 50 nm, and the average molecular weight of the polymer is 1
Greater than 0,000, preferably greater than 50,000. Small particle polymer systems have many advantages over systems containing large particles. This system is a colloidal dispersion and is usually clear and not cloudy. The small particles provide a uniform coating thickness and maintain good gas permeability of the porous substrate. Tetrafluoroethylene or other fluorinated monomer units in the polymer chain are useful to increase the thermal stability, hydrophobicity and oleophobicity of the substrate to which the polymer is applied.

The polymer thus formed is applied directly from the colloidal dispersion by immersing the substrate material in the dispersion, coating the substrate with the dispersion, or spraying the dispersion onto the substrate. can do. After coating the substrate, all remaining water, surfactant or polymerization initiator is heated with hot air, infrared rays, hot rolls, etc. (for example,
150-250 ° C.), steam stripping, vacuum evaporation and any other convenient method.

Further, the skeleton of the porous substrate is coated with the tetrafluoroethylene copolymer by melting the tetrafluoroethylene copolymer particles remaining in the internal structure forming the pores of the porous polymer substrate. can do. The removal of water and the like and the melting can be performed in the same process. In the present invention, when the skeleton of the porous polymer substrate is coated with the tetrafluoroethylene copolymer, it is adjusted so as to maintain the continuous pore structure of the substrate porous polymer material. In the fluorinated polymer obtained by the conventional aqueous emulsion polymerization, this pore structure is blocked due to the size of the particles, but as described above, the tetrafluoroethylene copolymer used in the present invention has an average particle size of Diameter 0.01
Even if the pore size is 1 because it is a fine particle of ~ 0.5 μm
Even if it is less than μm, and further less than 0.5 μm, a continuous pore structure can be maintained, and the porosity of the porous polymer material is not significantly reduced. As a result, the humidifying film of the present invention not only has water repellency and stain resistance, but also can retain a large moisture permeability.

Thus, the humidifying membrane provided by the present invention comprises a porous polymeric substrate, preferably a skeleton of expanded porous PTFE, coated with a hydrophobic and oleophobic tetrafluoroethylene copolymer and having continuous pores. Therefore, it is possible to maintain the high moisture permeability of the porous film while imparting stain resistance to the porous polymer substrate. Such a humidifying film of the present invention is in the form of a sheet and can be used in various forms. For example, a humidifying sheet having an integral three-layer structure can be formed by laminating the humidifying film of the present invention on both sides of a hydrophilic fabric such as a non-woven fabric, a woven fabric, and a knitted fabric. An appropriate number of humidifying sheets are provided at regular intervals to secure an air flow path. In this case, the humidifying water is held by the cloth of the intermediate layer, and the steam is released into the air through the humidifying films laminated on both sides. Alternatively, two sheet-like humidifying films of the present invention are stacked,
The end may be closed to form a bag, and humidifying water may be supplied into the bag to form a bag-shaped humidifying film. This bag-shaped humidifying film is provided by being spirally wound or pleated at regular intervals to secure an air flow path. Also in this case, the humidifying water is discharged to the outside as water vapor through the two humidifying films.

The humidifying membrane of the present invention can also be formed into a tubular shape for use. For example, a polymeric material molded into a tube shape by an extruder or the like is made into a base material by making it porous by a stretching treatment or the like, and by coating the particles of the tetrafluoroethylene copolymer into the tubular shape of the present invention. A humidifying film can be obtained. Alternatively, a tape-shaped porous polymer material may be spirally wrapped or sushi-wrapped and molded into a tube to form a substrate, and the organic polymer may be formed before or after forming the skeleton of the substrate. The tissue may be coated. A plurality of the tube-shaped humidifying membranes are provided at a predetermined interval in order to secure an air passage or a humidifying water passage. In this case, this tube-shaped humidifying film supplies the humidifying water to the inside or the outside thereof and supplies the air to the opposite side to move the water vapor through the humidifying film in the same manner.

The humidifying film of the present invention can be laminated on the humidifying film by optionally using a cloth such as a woven fabric, a non-woven fabric or a knitted fabric as a reinforcing material. This makes it possible to improve the strength of the humidifying film and the handleability of the humidifying film when manufacturing the humidifier.

[0042]

EXAMPLES In the following examples, the water pressure resistance, air permeability and moisture permeability were measured by the following methods. Water pressure resistance JIS L 1092 According to the method B of 5.1. In addition, the pressure resistance test of cutting oil also conformed to this.

Air permeability (Gurley number) Measured by an Oken type air permeability tester according to JIS L 1096 6.27, method B. Moisture permeability Measured by the method B (potassium acetate method) of JIS L 1099 4.2.

(Aqueous latex preparation example 1) Tetrafluoroethylene / fluoroacrylate copolymerization
In a 2 liter reactor, 1000 g deionized water, fluoroacrylate monomer or

[0045]

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(Zonyl TA-N, duPont) 50 g and ammonium perfluorooctanoate (Fluororad FC-143, 3
M) 90 g was added. The mixture was a clear microemulsion at 50 ° C, which was stirred at about 1200 rpm. The reactor was then evacuated and purged with tetrafluoroethylene gas three times to bring the oxygen content of the mixture below 30 ppm. Next, the temperature of the mixture was raised and maintained at about 75 ° C., and tetrafluoroethylene gas was introduced into the reactor so that the pressure inside the reactor was about 1500 kPa. 0.4 g of ammonium persulfate initiator dissolved in 40 g of water was pumped into the reactor to start the reaction. The reaction was terminated for about 42 minutes. At the end of the reaction, the pressure in the reactor was about 200 kPa, indicating that the amount of tetrafluoroethylene used during the polymerization reaction was sufficient.

The colloidal mixture formed by the above reaction was a clear dispersion and had a solid polymer content of about 11.9% by weight. The average particle size of the polymer is about 26 nm (0.26μ
m). Thermogravimetric analysis revealed that the polymer had a fluoroacrylate-rich portion of about 40% by weight and a tetrafluoroethylene-rich portion of about 60% by weight. This is because 40% by weight of the polymer decomposes at temperatures of 250-460 ° C, which is the typical decomposition temperature of polyfluoroacrylates, while 60% by weight of the polymer decomposes at temperatures of 460-640 ° C. This temperature is because it is a typical decomposition temperature of polytetrafluoroethylene. Analysis of the polymer with a differential scanning calorimeter showed three major endothermic peaks at 138 ° C.
Appeared at 219 ° C and 324 ° C.

(Aqueous latex preparation example 2) Tetrafluoroethylene / hexafluoropropylene
In a 2 liter reactor of luoroacrylate / copolymer , deionized water 1000 g, fluoroacrylate (Zonyl TA-N, duPont) 70 g, and ammonium perfluorooctanoate (Fluororad FC-143,3M) 130
g was added. The mixture was a clear microemulsion at 50 ° C, which was stirred at about 1200 rpm. The reactor was then evacuated and purged with tetrafluoroethylene gas three times to bring the oxygen content of the mixture below 30 ppm. The temperature of the mixture was then raised and held at about 90 ° C. Introduce tetrafluoroethylene and hexafluoropropylene gas mixture into the reactor and increase the pressure in the reactor to about 1500 kP.
a. At this time, the molar ratio of tetrafluoroethylene to hexafluoroethylene was about 70:30. Then water 40
0.4 g of ammonium persulfate dissolved in g was pumped into the reactor to start the reaction. The reaction was continued for about 234 minutes and terminated. At the end of the reaction, the reactor pressure is about 60
It was 0 kPa.

The colloidal mixture produced in the above reaction is a transparent dispersion and has a solid polymer content of about 8.4% by weight.
Met. The average particle size of the polymer is about 45 nm (0.045 μm)
Met. Thermogravimetric analysis showed that the polymer particles contained about 70% by weight fluoroacrylate-rich portion and about 30% by weight tetrafluoroethylene-rich portion. 70% by weight of the polymer decomposed at a temperature of 323 to 460 ° C, which is a typical decomposition temperature of polyfluoroacrylate, and decomposed at a temperature of 460 to 710 ° C, which is a typical decomposition temperature of polytetrafluoroethylene. 30 polymers
It was based on the fact that it was% by weight. As a result of differential scanning calorimetry, the polymer has three main endothermic peaks at 124 ° C and 235 ° C.
And 305 ° C.

(Aqueous latex preparation example 3) Tetrafluoroethylene / fluoroacrylate copolymerization
Body (core / shell structure) In a 2 liter reactor, deionized water 1000 g, fluoroacrylate (Zonyl TA-N, duPont) 4 g, and ammonium perfluorooctanoate (Fluororad FC-143,3M) 12 g
Was added. The mixture was a clear microemulsion at 50 ° C. and was stirred at a stirring speed of about 1200 rpm.
The reactor was then evacuated and purged with tetrafluoroethylene gas three times to bring the oxygen content in the mixture below 30 ppm. The temperature of the mixture was then raised and held at about 85 ° C. Next, 0.2 g of ammonium persulfate dissolved in 40 g of water was pumped into the reactor to start the reaction. The reaction continued for about 60 minutes. Most fluoroacrylate monomers polymerized to form tiny seed polymer particles. Next, tetrafluoroethylene was introduced into the reactor, and the pressure inside the reactor was set to about 1800 kPa. The reaction was continued while tetrafluoroethylene was involved in the polymerization, and tetrafluoroethylene was constantly supplied to the reactor to maintain the pressure at about 1800 kPa. The reaction time of tetrafluoroethylene was about 45 minutes to complete the reaction.

The colloidal mixture formed from the above reaction was a translucent semi-clear dispersion and had a solid polymer content of about 10% by weight. The average particle size of the polymer was about 76 nm (0.076 μm), the polymer particles had a core / shell structure, the core was polyfluoroacrylate and the shell was polytetrafluoroethylene. As a result of thermogravimetric analysis, the polymer particles were found to have a fluoroacrylate-rich portion of about 2% by weight and a tetrafluoroethylene-rich portion of 98% by weight. This is because 2% by weight of the polymer decomposes at the typical decomposition temperature of polyfluoroacrylates of 300-460 ° C and 98% by weight of the polymer of 460-760 ° C which is the typical decomposition temperature of polytetrafluoroethylene. Based on the fact that it was decomposed in As a result of differential scanning calorimetry analysis of the polymer, the main endothermic reaction peak was 330 ° C.

(Example 1) PTFE porous membrane (thickness: 50)
μm, porosity 80%, average pore size 0.2 μm, Gurley number 10 seconds) is immersed in a solution obtained by diluting the aqueous latex prepared in the aqueous latex preparation example 3 three times with distilled water to remove excess liquid by dropping. Place in an oven at 225 ° C for 3 minutes. By this treatment, water and the fluorinated surfactant were removed, and the fluorinated polymer was melted and fluidized. The Gurley number of the obtained film was measured and found to be 11 seconds, confirming that continuous pores were maintained.

The cutting oil resistance of this treated film was evaluated by a pressure resistance test using cutting oil for water supply pipes (Miyagawa 50W). In addition, a bag of 10 cm in length and 10 cm in width is also prepared from the above treated film, and tap water is continuously supplied into the bag at 60 ° C.
Blow dry hot air to the water inside the bag to 250cc through the membrane.
After evaporation of an amount of / cm ² (50 l), the water resistance test of the part of the film where the water inclusions were deposited was carried out.

For comparison, the same evaluation test as described above was performed on the same PTFE porous membrane as described above, which was not subjected to the organic polymer coating treatment. The results are shown in the table below. The table also shows the measured values of the moisture permeability of these films. Treated membrane Non-treated membrane Miyagawa 50W 10% liquid 0.165 0.000 Water pressure resistance (kg / cm ² ) Tap water 250cc / cm ² After evaporation 4.300 0.013 Water pressure resistance (kg / cm ² ) Permeability Wetness (g / m ² 24 hr) 72505 70210 (Example 2) PTFE porous body (thickness 50 μm, porosity 8)
0%, average pore diameter 0.2 μm, Gurley number 10 seconds, water pressure resistance 4 kg / cm ² ) polyester knit (200 denier, 200 g / m ² ) laminated to form a humidifying membrane (), and its PTFE Hydrophilic polyurethane (high ball FHP3000, WRGrace & Co.
() Was coated to a thickness of 30 μm to prepare a humidified film (). Further, a water-repellent treatment was carried out with a 3-fold dilution of the aqueous latex preparation (Preparation Example 2) to prepare a humidified film (), and the same tests as in Example 1 were carried out on the respective films for comparison.

The results are as follows, and as can be seen from the following, the humidifying film is more suitable as the humidifying film. Film film film Miyagawa 50W 10% solution 0.000 3.925 0.165 definitive Water pressure (kg / cm ²⁾ tap water 250 cc / cm ² evaporation 0.013 4.210 4.300 after the water pressure resistance (kg / cm ² ) Moisture permeability (g / m ² 24 hr) 70010 40000 72505 Gurley number (sec) 10 ∞ 11 (Example 3) PTFE porous body (thickness 50 μm, porosity 8)
PP non-woven fabric (thickness 1.0 μm, basis weight 125 g / m ² ) was heat-fused on 0%, average pore diameter 0.2 μm, slitted to a width of 25 mm, and then spirally wrapped (heat treatment). The non-woven fabric of the polymerized portion was heat-fused to prepare a humidifying tube () having an inner diameter of 12 mm and a wall thickness of 0.5 mm. After that, a three-fold diluted product of the aqueous latex modifier (Preparation Example 2) with distilled water was applied to the porous portion, impregnated and dried at 225 ° C. to form a tubular humidifying membrane (). A test according to Example 1 was conducted on this tubular humidifying membrane, and the results are shown in the table below. From this result, the optimum humidifying film was obtained even if the shape was changed.

[0056] processing tube () untreated tubes () pressure test Miyakawa 50 W 10% solution 0.209 0.006 (kg / cm ²⁾ moisture permeability ^{(g / m 2 24hr) 24950} 20100 Gurley number (seconds) 153 150 (Example 4) An adhesive (urethane resin) was applied to one surface of the fluorinated organic polymer-treated PTFE film prepared in Example 1 by using a gravure pattern roll (set the opening ratio to 70%), and this surface was applied to this surface. Acrylic non-woven fabric (thickness 3 mm, basis weight 50)
g / m) and pressure-bonded by roll under the conditions of a pressure of 3 kg / cm ² and a speed of 5 m / min. Then, using the same method and conditions on the other side of the acrylic non-woven fabric, the same organic polymer treated PTF
The E film was crimped. The moisture permeability of the humidifier sheet, which has a continuous three-layer structure like this, is 51000 g / m ² · 24 hr.
Met.

(Embodiment 5) Referring to FIG.
The moisturizing sheet 11 prepared as described above has a width of 46 mm and a length of 9
The peripheral edge portion 12 is sealed with a thickness of 90 mm and a thickness of 2.0 mm. Further, a water injection port 13 having a diameter of 6 mm is provided near one end. 25 such humidifying sheets and a width of 4
26 sheets of polyethylene corrugated sheet 14 having a length of 5 mm, a length of 945 mm, a pitch of 6.2 mm and a height of 2.5 mm, and 26 sheets of a vinyl chloride resin sheet 15 having a width of 46 mm, a length of 46 mm and a thickness of 3.0 mm The layers were laminated, and a vinyl chloride adhesive was applied to the shaded portion 16 in FIG. 1 for adhesion. The water injection port 13 is also provided in the resin plate 15. Therefore, the water injection port forms a through hole from the uppermost resin plate 15 to the lowermost moisturizing sheet 11, and is closed by the lowermost resin plate 15.

The humidifying sheet 20 thus laminated in FIG.
Is schematically shown. Figure 3 shows this laminated product with a mounting frame (outer dimension 1
Made of hot-dip galvanized steel plate of 000mm x 150mm x 50mm)
21 and the tube connector (outer diameter 8 mm,
The inside of the humidifying unit was completed by attaching the inner diameter 6 mm) 22. Supply the clean water to the completed humidification unit, and the humidity is 20 at 45 ° C.
% Air was blown at a wind speed of 1.5 m / sec for testing. At this time, 1.5 l / h was recorded as the humidifying capacity. The pressure loss of air was 7 Pa or less.

[0059]

As described above, according to the present invention, it has stain resistance to oily components such as cutting oil, organic and inorganic impurities in humidifying water, and causes white powder pollution. It is possible to provide a humidifying membrane that supplies clean humidified air. Since the structure of the humidifying membrane of the present invention maintains the continuous porous structure, the humidifying water can be easily introduced during the operation of the humidifier, and the humidifying ability is excellent. Moreover, the humidifying membrane of the present invention is obtained by coating the skeleton of a porous polymer base material including expanded porous polytetrafluoroethylene with a tetrafluoroethylene copolymer, whereby the tetrafluoroethylene copolymer has a porous structure. It can be firmly bonded to the skeleton of a high-quality polymer substrate, and can have excellent properties such as heat resistance, chemical resistance, and the like, as well as water repellency, oil repellency, and stain resistance.

[Brief description of the drawings]

FIG. 1 shows how humidifying sheets for a humidifying unit are stacked.

FIG. 2 shows the laminate of FIG.

FIG. 3 shows an example of a humidifying unit.

[Explanation of symbols]

 11 ... Humidification sheet 12 ... Water injection port 14 ... Spacer 15 ... Resin plate 21 ... Mounting frame

Claims (7)

[Claims] 1. A humidifying membrane for a humidifier, wherein the skeleton of the porous polymer substrate is covered with a tetrafluoroethylene copolymer and has continuous pores. 2. The humidifying method according to claim 1, wherein the tetrafluoroethylene copolymer is a copolymer of tetrafluoroethylene and a monomer selected from acrylate, methacrylate, styrene, acrylonitrile, vinyl, allyl and alkene. film. 3. The humidifying membrane according to claim 1, wherein the tetrafluoroethylene copolymer is a copolymer of fluoroacrylate, hexafluoropropylene and tetrafluoroethylene. 4. The humidifying membrane according to claim 1, wherein the porous polymer-based material is stretched porous polytetrafluoroethylene. 5. The average pore diameter of the porous polymer-based material is 0.
1. The pore size is 1 to 1 .mu.m and the porosity is 60 to 90%.
The humidifying membrane described in 2, 3, or 4. 6. The humidifying film according to claim 1, wherein a reinforcing material is laminated on the humidifying film. 7. Tetrafluoroethylene copolymer particles are present on the porous polymer substrate and the particles are 0.01
Applying an aqueous latex having an average particle size of ˜0.5 μm, removing water and surfactant present and then melting the polymer to coat the substrate skeleton. Manufacturing method of humidifying membrane for humidifier.