KR20030032095A - Humidity sensor comprising polymeric membrane - Google Patents

Abstract

PURPOSE: A high polymer film humidity sensor is provided to measure and adjust humidity of a humidifier and a dehumidifier in an eco-friendly manner by installing the high polymer film humidity sensor in the humidifier and the dehumidifier. CONSTITUTION: A high polymer film humidity sensor includes an upper electrode(1), a lower electrode(3) arranged in opposition to the upper electrode(1), a humidity reducing film(2) positioned between the upper electrode(1) and the lower electrode(3), and a substrate(4) for supporting the upper and lower electrodes(1,3). The humidity reducing film(2) is made by cross-linking a first polymer, which is obtained by polymerizing a vinyl monomer including a carboxyl radical and at least one or two vinyl comonomers, a second polymer, which is obtained by polymerizing a vinyl monomer including a hydroxyl radical and at least one or two vinyl comonomers, and a polymer including carboxyl and hydroxyl functional groups.

Description

Humidity sensor comprising polymeric membrane

The present invention relates to a polymer film humidity sensor. More specifically, the present invention is a copolymer of a vinyl monomer containing a carboxyl group and at least one or more vinyl comonomers, and a second copolymer obtained by copolymerizing one or more vinyl comonomers with a vinyl monomer including a hydroxy group. The present invention relates to a capacitive polymer film humidity sensor comprising a moisture absorbent formed by crosslinking a copolymer including carboxy and hydroxy functional groups simultaneously in one copolymer.

Capacitive polymer membrane humidity sensor uses the characteristic that the capacitance changes according to the moisture absorption and desorption of water by the polymer moisture absorbing material. When the water is adsorbed, the humidity sensor uses the characteristic that the dielectric constant is remarkably changed by the characteristic of the permanent dipole of water. Water molecules are relatively small in size but are liquids with polar groups and tend to form hydrogen bonds with materials in the solid state. Hygroscopicity in highly polar polymers is strongly influenced by this action, and in weakly polar polymers, the association of absorbed water molecules, ie 2 to 10 molecules, act as a single molecule. Clustering is a phenomenon. In hydrophilic polymers such as cellulose and proteins, each polar group acts strongly with water molecules, whereas in hydrophobic polymers only a very small amount of water is absorbed. However, as the polar group in the polymer matrix increases, the sorption of water (sorptive affinity) increases, which determines the water's access to the polar group, that is, the relative strength of water-water and water-polymer bonds, and the degree of crystallinity of the polymer matrix. Is a very important factor, but the relationship between the degree of evolution and the polar group is difficult to explain easily.

The capacitance is accompanied by a change according to the type of dielectric and the distance between the electrodes, which is represented as the final capacitance. The material between the upper electrode and the lower electrode has an intrinsic dielectric constant depending on the polymer used, which has a great influence on the capacitance. Therefore, a polymer capable of absorbing water molecules can be used as a moisture sensitive material. Although many cellulose derivatives have been used as such polymer dielectrics, the change in time is large due to deterioration of safety at high temperature and high humidity and durability of organic vapors. Recently, the crosslinked methacrylate polymer has been used for good moisture absorption characteristics. Although manufacturing a capacitance-type polymer film humidity sensor having a, after applying a moisture-sensitive film containing a monomer, it must be cross-linked by using a radical polymerization, etc., which is pointed out as a manufacturing difficulty. In addition, new forms of polyimide, polyethylene terephthalate, polysulfone, polyvinyl chloride, polyphosphazene, and the like have been studied as a moisture sensitive membrane of a capacitive polymer film humidity sensor. Since the dielectric constant of the hydrophobic polymer is very low compared to the dielectric constant of water, the dielectric constant is greatly changed when water molecules enter. However, such a hydrophobic polymer has a large hysteresis when the absorbed moisture forms a cluster. Therefore, it is necessary to develop a polymer in which the water molecules do not form clusters. When the absorbed water molecules are a small amount of water that does not form clusters, the apparent dielectric constant increases and the capacitance increases linearly with relative humidity. In addition, the apparent dielectric constant is not affected by the organic solvent vapor can be a good moisture film.

In order to select a polymer moisture sensitive material as a capacitive humidity sensor, it is necessary to have a hydrophilic group suitable for the humidity sensor in the polymer structure. However, there are groups with strong hydrophilic properties such as hydroxyl group (-OH), amine group (-NH ₂ ), carboxyl group (-COOH) and amide group (-CONH-) that absorb large amounts of water according to the change of relative humidity. The materials are not suitable as a moisture sensitive material for capacitive humidity sensors. Moisture absorbing material should be smoothly adsorbed and desorbed under the influence of hydrophilic group. The hysteresis, which is the speed difference between adsorption and desorption, must satisfy about ?? 3% RH or less.

Polyimide, cellulose-based materials and polymethacrylate derivatives are mainly used as polymers as capacitive moisture-sensitive materials, and in the case of polyimide, C = O and cellulose materials in imide-based hydroxy groups are highly hydrophilic. It is applied by measuring the capacity change according to humidity change by substituting hydrophobic groups. The material used as the humidity-sensitive material in the capacitive humidity sensor has the property of adsorbing moisture, but it should not react with water and should not be deteriorated at high temperature.

As is well known, polyimides originate from Dupont, USA, sold under the trade names Kapton and Vespel. Polyimide can be prepared by reaction of poly (amic acid) with diamine in the presence of a solvent such as N-methyl pyrrolidone (NMP; N-methyl pyrrolidone). Can be. Excellent in dimensional stability, chemical resistance, oxidation resistance, mechanical properties, etc., high temperature is required when forming the film by imidization, and the manufacturing process is very complicated because the sandwich electrode is formed by vacuum deposition after film formation. In addition, the yield was determined depending on the uniformity of the film, there was a problem that the productivity is low.

In the cellulose series, acylated derivatives are mainly applied, and most of the materials having carbonyl groups as hydrophilic groups are used in the moisture-sensitive film. In this case, the hydrophilic group decreases and the hysteresis appears small, but the sensitivity decreases greatly. Therefore, after acylation, an appropriate amount of hydrophilic strong hydroxyl group should be used so as to adjust the amount to remain. However, as mentioned above, the presence of a strong hydrophilic group forms a cluster with moisture, which adversely affects adsorption and desorption, so that the performance as a moisture-sensitive film becomes poor. For example, the difference in the humidity sensitivity among the derivatives of acetyl cellulose is due to the amount of the hydroxy group having strong hydrophilicity. That is, the hydrophilic hydroxy group is easy to adsorb moisture, and the capacity value and humidity change of acetyl cellulose are large, and it is difficult to separate the moisture adsorbed to the hydroxy group, resulting in large hysteresis. As can be seen from the above two examples, the capacitive humidity sensor must be manufactured by proper introduction of hydrophilic and hydrophobic groups, that is, molecular design, for application as a moisture-sensitive film.

It is an object of the present invention to provide a first copolymer obtained by copolymerizing a vinyl monomer containing a carboxyl group with one or more vinyl comonomers and a second copolymer obtained by copolymerizing a vinyl monomer containing a hydroxyl group and one or more vinyl comonomers. The present invention provides a capacitive polymer membrane humidity sensor comprising a moisture absorbent formed by crosslinking a copolymer including carboxy and hydroxy functional groups simultaneously in two copolymers.

1 is a configuration diagram schematically showing an electrode of a polymer film humidity sensor according to the present invention.

2 is a graph showing the capacitance and hysteresis characteristics of the polymer film humidity sensor manufactured according to the present invention.

3 is a graph showing the water resistance characteristics of the polymer membrane humidity sensor manufactured according to the present invention.

4 is a graph showing the response speed of the polymer film humidity sensor manufactured according to the present invention.

※ Explanation of code for main part of drawing

1: upper electrode 2: moisture-sensitive film

3: lower electrode 4: substrate

The polymer film humidity sensor according to the present invention includes an upper electrode and a lower electrode fixed at positions facing each other, a moisture sensitive film positioned between the upper electrode and the lower electrode, and a substrate supporting the entire moisture sensitive film and the electrodes. A second copolymer obtained by copolymerizing a vinyl monomer containing a carboxyl group with one or two or more vinyl comonomers and a vinyl monomer containing a hydroxyl group and one or two or more vinyl comonomers; It is made by crosslinking the copolymer which simultaneously contains a carboxy and a hydroxy functional group in one copolymer.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the polymer film humidity sensor according to the present invention, the upper electrode 1 and the lower electrode 3 fixed at positions facing each other, the moisture-sensitizing film 2 positioned between the upper electrode 1 and the lower electrode 3, and the And a substrate (4) for supporting the entire moisture sensitive membrane (2) and the electrodes, wherein the moisture sensitive membrane (2) is a first air copolymerized with a vinyl monomer containing a carboxyl group and one or more vinyl comonomers It is characterized in that it is made by crosslinking a copolymer comprising a carboxyl and hydroxy functional group simultaneously in a second copolymer or a copolymer in which a vinyl monomer including a copolymer and a hydroxyl group and one or two or more vinyl comonomers are copolymerized.

The manufacturing process of the capacitive polymer film humidity sensor can be summarized as follows.

Usually, in the capacitive polymer film humidity sensor, the lower electrode 3 is formed by depositing gold on the substrate 4, and forms the moisture sensitive film 2 on the lower electrode 3. The substrate 4 is electrically non-conductive here, and serves only to mechanically support the electrodes and the moisture sensitive film 2 formed thereon. In addition, the deposition of gold for electrode formation on the substrate 4 can be accomplished by conventional metal deposition methods, which can be easily understood by those skilled in the art.

The moisture-sensitive film 2 is formed by copolymerizing a solution of a first copolymer obtained by copolymerizing a vinyl monomer containing a carboxyl group with one or more vinyl comonomers and a vinyl monomer containing a hydroxyl group and one or more vinyl comonomers. It consists of applying a copolymer solution containing carboxy and hydroxy functional groups simultaneously in a mixed solution or a copolymer of a solution of the second copolymer, and finally crosslinking by thermal crosslinking or addition of a crosslinking agent. Then, a metal film is vacuum-deposited as the upper electrode 1 on the moisture sensitive film 2 to finally manufacture a capacitive humidity sensor.

The shape of the electrode is formed in a bite shape, a rectangular shape, a circular shape, a text door shape, and the like, and the shape thereof may be changed in various ways. The electrode uses only the upper electrode 1 or the lower electrode 3, and the other electrode may act as an auxiliary electrode for imparting dielectric properties horizontally. In the case of such an electrode, the electrode is easy to manufacture. As a result, the manufacturing cost can be greatly reduced, and the electrode pattern of the conventional resistance humidity sensor can be used as it is. In addition, after the application of the moisture-sensitive film 2, by forming a film by simple vapor deposition of the auxiliary electrode can greatly contribute to the mass productivity.

The material forming the electrode is made of gold or platinum, which is not corrosive even under various adverse conditions. Silk electrode printing or vacuum deposition is used to form the electrode. A substrate 4 is required except for a humidity sensor in which a moisture-sensitive film 2 is placed in the center and a electrode deposited on both sides in the form of a sandwich, which is used as a substrate of an electronic material. The substrate was selected. In particular, in the case of an electrode produced by vacuum deposition, a silver-palladium pad capable of soldering a lead wire is formed in advance so that the deposition electrode is connected to this portion, and a conductive silver paste composition capable of low-temperature firing is possible. It can be prepared using (silver paste).

The copolymer comprising both carboxy and hydroxy functional groups in one copolymer and the vinyl comonomer used in the preparation of the first copolymer and the second copolymer is N, N-dimethylacrylamide, N, N-dimethylmetha. N-substituted amide vinyl monomers such as krylamide; Alkoxy acrylate vinyl monomers, such as methoxy ethyl acrylate, methoxy ethyl methacrylate, ethoxy ethyl acrylate, and ethoxy ethyl methacrylate; Vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidine, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole. Vinyl monomers such as vinyloxazole, vinylmorpholyl, N-vinylcarboxylic acid amide, styrene, p-methoxystyrene, p-chlorostyrene, p-methylstyrene, α-methylstyrene, vinyltoluene, and N-vinyl caprolactam ; Cyanoacrylate vinyl monomers such as acrylonitrile and methacrylonitrile; Polyethylene glycol acrylate, polyethylene glycol methacrylate, polypropylene glycol acrylate, polypropylene glycol methacrylate, methoxy ethylene glycol methacrylate, methoxy polyethylene glycol methacrylate, methoxy polypropylene glycol methacrylate, methoxy polypropylene methacrylate Glycol-based acrylic ester monomers such as glycol; Acrylic ester monomers such as tetrahydroperpril acrylate, tetrahydroperpril methacrylate and 2-methoxyethyl acrylate; Or a group consisting of two or more of these mixtures.

The vinyl monomer including the carboxyl group and one or two or more vinyl comonomers may be copolymerized to obtain a copolymer including carboxy and hydroxy functional groups simultaneously in the first copolymer and one copolymer.

Examples of the vinyl monomer including the carboxyl group include carboxyl group-containing vinyl monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; Maleic anhydride. It may be selected from the group consisting of acid anhydride vinyl monomers such as itaconic anhydride or a mixture of two or more thereof. In the first copolymer formed by copolymerization of the vinyl monomer containing the carboxyl group and the vinyl comonomer, the vinyl monomer including the carboxyl group may have an amount of 1 to 30 mol% of the functional group of the carboxyl group. When the amount of the vinyl monomer containing the carboxyl group is less than 1 mol%, crosslinking may be incomplete, resulting in a decrease in reliability of high temperature, high humidity, and alcohol vapor, and when it exceeds 30 mol%, a crosslinking agent Even if the unreacted functional group remains, there may be a problem that the hysteresis and response speed characteristics are reduced.

The vinyl monomer including the hydroxy group and one or two or more vinyl comonomers may be copolymerized to obtain a copolymer including carboxy and hydroxy functional groups simultaneously in the second copolymer and one copolymer.

Vinyl monomers containing the hydroxy group include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxyhexyl acrylate, It may be selected from the group consisting of methacrylic acid hydroxyhexyl or a mixture of two or more thereof. In the second copolymer formed by copolymerization of the vinyl monomer containing the hydroxy group and the vinyl comonomer, the vinyl monomer including the hydroxy group may have an amount of 1 to 30 mol% of the functional group of the hydroxy group. Even when the amount of the vinyl monomer including the hydroxy group is less than 1 mol%, crosslinking may be incomplete, resulting in a decrease in reliability of high temperature, high humidity, and alcohol. Even if the unreacted functional group remains, there may be a problem that the hysteresis and response speed characteristics are reduced.

In addition, as a crosslinking agent of the first copolymer and the second copolymer or a crosslinking agent of a copolymer including carboxy and hydroxy functional groups simultaneously in one copolymer, an isocyanate crosslinking agent, a carbodiimide crosslinking agent, a polyoxazoline crosslinking agent, melamine It may be selected from the group consisting of a crosslinking agent, a poly (N-alkanol) acrylamide crosslinking agent, an aziridine crosslinking agent or a mixture of two or more thereof. The crosslinking agent may vary depending on the characteristics of the crosslinking agent used, but it is preferable to add a sufficient amount to react with all crosslinking functional groups, which can be easily empirically obtained by theoretical calculations and repeated experiments. It can be.

As shown in FIG. 1, it is a gold electrode of a moon-moon form as an electrode, it forms using the mask which formed the pattern according to the shape of an electrode, and forms an electrode by vacuum-depositing gold. The soldering pad portion may be a paste containing silver and palladium in a ratio of 6: 1. The upper electrode 1 vacuum-deposited has a great influence on the adsorption and desorption of moisture, and thus proceeds by adjusting the deposition thickness.

In addition, the polymer membrane used as the moisture-sensitive membrane in the polymer membrane humidity sensor according to the present invention is a vinyl monomer comprising a first monomer and a hydroxy group copolymerized with a vinyl monomer containing a carboxyl group and one or more vinyl comonomers as described above; It can be made by crosslinking the second copolymer copolymerized with one or two or more vinyl comonomers, and also for simplifying the reaction, a vinyl monomer comprising a carboxyl group in one copolymer, a vinyl monomer comprising a hydroxy group and 1 Or it can also be used as a moisture sensitive film formed by crosslinking two or more vinyl copolymers.

As the monomer of the copolymer comprising both the carboxyl group and the hydroxyl group in the one copolymer to form a crosslinked moisture-sensitive film, the same monomers as those of the first copolymer and the second copolymer may be used. Or a selected from the group consisting of two or more of these may be used. Hereinafter, preferred embodiments and comparative examples of the present invention will be described.

The following examples are intended to illustrate the invention and should not be understood as limiting the scope of the invention.

Example 1

As shown in Table 1, a first copolymer obtained by copolymerizing a vinyl monomer containing a carboxyl group and one or two or more vinyl comonomers and a vinyl monomer comprising a hydroxyl group and one or two or more vinyl comonomers as a moisture sensitive agent. Each dipolymer was synthesized. In the preparation of the first copolymer and the second copolymer, 40 g of methyl methacrylate, 10 g of ethyl acrylate and 5 g of methacrylic acid are first mixed as monomers, and the initiator α, α'-azobisisobutyronitrile is added thereto. 0.1 g was dissolved in 200 g of a 1/1 mixture (volume / volume) of ethyl acetate / toluene, degassed, and subjected to radical polymerization at 60 ° C. for 24 hours to synthesize a first copolymer. After the polymerization was completed, methylene chloride was added and the solution was reprecipitated in n-hexane to obtain a first copolymer. After repeating the reprecipitation process once more, it was vacuum dried to obtain a white powdery first copolymer.

The other copolymer was mixed with 40 g of methyl methacrylate, 10 g of ethyl acrylate, and 5 g of 2-hydroxyethyl methacrylate, and 0.1 g of initiator α, α'-azobisisobutyronitrile was added to ethyl acetate / toluene. It was dissolved in 200 g of 1/1 mixed solution (volume / volume), and the second copolymer was synthesized by performing radical polymerization at 60 ° C. for 24 hours under a nitrogen atmosphere. After the polymerization was completed, methylene chloride was added and reprecipitated in petroleum ether to obtain a second copolymer. After repeating the reprecipitation process once more, it was vacuum dried in a vacuum oven at 50 ℃ to obtain a white powdery second copolymer.

20 g of the first copolymer was homogeneously dissolved in 400 g of dimethyl sulfoxide, prepared as a solution, put in a container, and 20 g of the second copolymer was uniformly dissolved in 400 g of dimethyl sulfoxide in a separate container to prepare a solution. . After mixing the first copolymer solution and the second copolymer solution under constant conditions of 5 ° C. and 60% RH (relative humidity), 1 g of carbodiimide-based crosslinking agent (trade name XL-29S (XL-29SE) , Union Carbide Co., Ltd., United States of America was added to prepare a uniform solution. The moisture sensitive film 2 was coated on the lower electrode 3 using a spin coater to prepare an electrode to which the moisture sensitive film 2 according to the present invention was applied. The electrode on which the moisture-sensitive film 2 is applied is left to stand at room temperature immediately while being horizontally dried for 10 minutes, and then gradually heated up and heated at 60 ° C. for 4 hours and at 130 ° C. for 2 hours to perform a crosslinking reaction. It was. After crosslinking progressed, it vacuum-dried to form the electrode to which the crosslinked copolymer moisture sensitive film 2 was apply | coated. During deposition, the distance between the gold target and the sample coated with the moisture sensitive film 2 was 20 mm and the current was 6 mA during deposition. At this time, the resistance between the upper electrodes 1 was deposited for about 4 minutes to be 20 Ω or less, thereby allowing the upper electrode 1 It was formed, using this to prepare a polymer film humidity sensor according to the present invention.

Examples 2-5

The first copolymer and the second copolymer were prepared in the same manner as in Example using monomers according to Table 1, and in Example 3, since itaconic acid had an acid value of 2, only half of the amount was used. Also, a polymer film humidity sensor was manufactured in the same manner as in Example 1.

Example 6

As shown in Table 1, the copolymer including a carboxyl group and a hydroxy group at the same time as a humectant is first mixed with 40 g of methyl methacrylate, 10 g of benzyl methacrylate, 5 g of methacrylic acid, and hydroxypropyl methacrylate as monomers. 0.1 g of the initiator α, α'-azobisisobutyronitrile was dissolved in 200 g of a 1/1 mixture (volume / volume) of ethyl acetate / toluene, degassed, and then subjected to radical polymerization at 60 ° C. for 24 hours. The first copolymer was synthesized. After the polymerization was completed, methylene chloride was added and the solution was reprecipitated in n-hexane to obtain a copolymer including both carboxyl groups and hydroxy groups in one copolymer. After the reprecipitation process was repeated once more, vacuum drying was performed to obtain a copolymer including both carboxyl and hydroxy groups in one copolymer of white powder.

1 g of a melamine crosslinking agent (trade name Cymel 304 (CYMEL-304, Geneva, USA) was added to a solution in which 20 g of a copolymer including both carboxyl and hydroxy groups in a single copolymer was homogeneously dissolved in 400 g of dimethyl sulfoxide. A solution was prepared on the lower electrode 3 using a spin coater to prepare an electrode coated with the moisture sensitive film 2 according to the present invention. The coated electrode was left to stand at room temperature immediately while being horizontally dried for 10 minutes, and then gradually heated up to 4 hours at 60 ° C. and then heated at 130 ° C. for 2 hours to perform a crosslinking reaction. The formation of was proceeded in the same manner as the method performed in Examples 1 to 5.

The capacitance and hysteresis characteristics at 30 to 95% RH (relative humidity) of the polymer film humidity sensor manufactured in the above examples are shown in FIG. 2.

In addition, the environmental test was performed under the conditions shown in Table 2, and the results are shown in Table 3 and FIG. 3 (water resistance characteristics) and FIG. 4 (response speed), respectively.

As a result of the synthesis of the above embodiments, the polymer film humidity sensor made using the moisture absorbent according to the present invention is measurable at a relative humidity of 0 to 100% RH, at a temperature of 0 to 60 ° C, excellent water resistance, and various organic It could be seen that the solvent and oil showed durability.

Therefore, according to the present invention, it is expected to have long-term stability and high reliability due to excellent water resistance and environmental resistance of the moisture sensitive film 2, and is useful as a humidity sensor of machines and devices that need to control humidity such as various humidity measurements, humidifiers and dehumidifiers. It is effective to provide a polymer film humidity sensor that can be used.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (5)

The upper electrode and the lower electrode fixed to the position facing each other, including a damping film positioned between the upper electrode and the lower electrode and a substrate for supporting the entire damping film and the electrodes, the damping film includes a carboxyl group The first copolymer and the hydroxy group copolymerized with a vinyl monomer and one or two or more vinyl comonomers and the second copolymer or one or more vinyl comonomers copolymerized with a carboxyl group and a hydroxy group in one copolymer. Polymer membrane humidity sensor, characterized in that made by cross-linking the copolymer containing all. The method of claim 1, The vinyl comonomer is N-substituted amide vinyl monomers such as N, N-dimethyl acrylamide, N, N-dimethyl methacrylamide; Alkoxy acrylate vinyl monomers, such as methoxy ethyl acrylate, methoxy ethyl methacrylate, ethoxy ethyl acrylate, and ethoxy ethyl methacrylate; Vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidine, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, Vinyl monomers such as vinylmorpholyl, N-vinylcarboxylic acid amide, styrene, p-methoxystyrene, p-chlorostyrene, p-methylstyrene, α-methylstyrene, vinyltoluene and N-vinyl caprolactam; Cyanoacrylate vinyl monomers such as acrylonitrile and methacrylonitrile; Polyethylene glycol acrylate, polyethylene glycol methacrylate, polypropylene glycol acrylate, polypropylene glycol methacrylate, methoxy ethylene glycol methacrylate, methoxy polyethylene glycol methacrylate, methoxy polypropylene glycol methacrylate, methoxy polypropylene methacrylate Glycol-based acrylic ester monomers such as glycol; Acrylic ester monomers such as tetrahydroperpril acrylate, tetrahydroperpril methacrylate and 2-methoxyethyl acrylate; Or the polymer membrane humidity sensor, characterized in that selected from the group consisting of two or more of them. The method of claim 1, The vinyl monomer containing the carboxyl group may include carboxyl group-containing vinyl monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; The polymer film humidity sensor, characterized in that selected from the group consisting of an acid anhydride vinyl monomer such as maleic anhydride, itaconic anhydride or a mixture of two or more thereof. The method of claim 1, The vinyl monomer containing the hydroxy group is hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxyhexyl acrylate, meta The polymer membrane humidity sensor, characterized in that selected from the group consisting of hydroxyhexyl acrylate or a mixture of two or more thereof. The method of claim 1, In the crosslinking of the first copolymer and the copolymer including both the carboxyl group and the hydroxy group in the second copolymer or one copolymer, the crosslinking agent is an isocyanate crosslinking agent, a carbodiimide crosslinking agent, a polyoxazoline crosslinking agent, a melamine crosslinking agent, a poly ( The polymer membrane humidity sensor, characterized in that selected from the group consisting of N-alkanol) acrylamide crosslinking agent, aziridine crosslinking agent or a mixture of two or more thereof.