KR100308774B1 - Electrical resistance humidity sensor comprised of an organic polymer - Google Patents

Abstract

An electrical resistance organic polymer humidity sensor using a characteristic in which impedance changes according to humidity change in the air is disclosed using a methacrylic acid alkyl ester monomer and a methacrylic acid alkyl ester polymer containing a metal salt as a moisture sensitive film as a polymer film for sensing humidity. have. According to the present invention, the polymer is polymerized with a polymethacrylic acid alkyl ester by a general method using a methacrylic acid alkyl ester as a monomer, and then the polymethacrylic acid alkyl ester is reacted with a hydrogen halide in the presence of an acidic solution to give a hydroxy group an alkyl polymethacrylate. It introduces into ester and synthesize | combines polyalkylmethacrylic acid with large molecular weight. Next, the hydroxy group-introduced polymethacrylic acid alkyl ester is hydrolyzed with a hydroxide of an alkali metal or alkaline earth metal to replace hydrogen of the carboxylic acid portion of the polymethacrylic acid alkyl ester with a counter ion. After forming a moisture-sensitive film made of a polyalkyl methacrylate alkali metal salt or a polyalkyl methacrylate alkaline earth metal salt, a pair of terminals, a platinum electrode and a humidity electrode made of an electrode snap containing silver-palladium were deposited thereon and dried. Make a humidity sensor.

Description

Electrical resistance humidity sensor comprised of an organic polymer}

The present invention relates to a humidity sensor using an organic polymer film containing a metal salt as a moisture-sensitive film, and more particularly, to a moisture-sensitive film, a methacrylic acid alkyl ester monomer and a methacrylic acid alkyl ester polymer containing a metal salt as a moisture-sensitive polymer film. The present invention relates to an electrical resistance organic polymer humidity sensor using a characteristic in which impedance changes according to a change in humidity in the air.

The electrical resistance organic polymer film humidity sensor is a humidity sensor that senses humidity by using the phenomenon that the impedance of the polymer film changes as the humidity sensitive film is applied to the electrode formed on the alumina substrate. to be.

The electrical resistance humidity sensor using the electrolyte polymer membrane as a moisture absorber exhibits electrical conductivity after dissociation of the electrolyte polymer membrane after absorbing the surrounding moisture, so that the impedance is continuous between 0 to 100% RH (Relative Humidity). To change. Therefore, the relative humidity can be measured accurately.

Conventional organic polymer film humidity sensor can be largely divided into anionic polymer humidity sensor and cationic polymer film humidity sensor. Anionic polymers are polymers in which the main chain of the polymer acts as a cation and the relative ion (gegen ion) affects the electrical conductivity. Cationic polymers are polymers in which the main chain of the polymer acts as an anion and affects electrical conductivity. It refers to a polymer in which the counterion is a cation.

Anionic polymer membrane humidity sensors include 1- (2-hydroxy) -3-methacryloxypropyl trimethylammonium chloride, quaternized poly (4-vinyl pyridine), N, N, N-trimethyl ammonoethyl methacrylamide Halide, N, N-dimethyl aminoethyl methacrylamide, allyl dimethylaminopropyl diallyl ammonium chloride and sulfur dioxide copolymer, 2-methacryloxyethyl alkyldimethylammonium halide, acrylic, vinyl, styrene or methacryoxyoxyalkyl dimethylamino Ethyl phosphate, N, N-dimethyl-3,5-dimethylene piperidinium chloride, quaternary alkylammonium sulfonate, chloromethyl styryl ammonium salt, polyionene and a trialkoxy quaternary ammonium salt of styrene or methacrylic acid Is used.

Recently, monomers including phosphonium salts and sulfonium salts have been used, and quaternary ammonium salts have been used for most humidity sensors, and some have been put to practical use.

However, in anionic moisture sensitive materials, since the counterion is an anion, the ion radius is larger than that of the cation. Therefore, since the ion mobility is smaller than the cation, the response speed of the humidity sensor is lowered, which makes it difficult to use the device in which the response speed is important.

Therefore, in order to improve the response speed, the use of a cationic moisture sensitive material is preferable. Monomers used as cationic moisture sensitive materials are mainly salts of sulfonic acid, carboxylic acid and phosphoric acid.

However, in the cationic moisture-sensitive material, the polymerization is difficult, and even if it is polymerized, there is a problem that the water resistance of the humidity sensor is greatly reduced due to the small molecular weight. In particular, when polymerizing polyalkylmethacrylic acid to polymerize from alkylmethacrylic acid as a monomer, it is impossible to obtain a polymer having a molecular weight of 100,000 or more because the carboxyl group forms a resonance structure and prevents polymerization from occurring. Moreover, even if it is a commercial polymethylmethacrylic acid, molecular weight becomes 10,000 or more.

The present invention has been made to solve the conventional problems and problems as described above, the object of the present invention has excellent impedance characteristics in the range of commercial humidity and in particular the response speed is important, the response speed is important devices and humidifiers, dehumidifiers, humidity An object of the present invention is to provide an electrical resistance type cationic organic polymer humidity sensor that can be used in a device requiring humidity measurement such as a controller or a dryer.

1 is a structural diagram of an electrical resistance organic polymer humidity sensor manufactured according to the present invention,

2 is a graph showing the resistance characteristics of the electrical resistance organic polymer humidity sensor manufactured according to the present invention, and

3 is a graph showing the response speed of the electrical resistance organic polymer humidity sensor manufactured according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: organic polymer humidity sensor 12: moisture sensitive film

14 electrode 16 electrode snap

18: terminal

In order to achieve the above object, the present invention,

An electric resistance organic polymer humidity sensor comprising a moisture sensitive film, an electrode maintaining electrical contact with the moisture sensitive film, an electrode snap fixing the electrode, and a terminal connecting the electrode to the outside,

The moisture-sensitive film polymerizes the methacrylic acid alkyl ester to form a polymethacrylic acid alkyl ester, reacts it with a hydrogen halide in the presence of an acidic solution to introduce a hydroxy group, and the polyalkylmethacrylic acid to which the hydroxy group is introduced is alkali metal or alkaline earth. The present invention provides an electrical resistance organic polymer humidity sensor comprising a polyalkyl methacrylate alkali metal salt or a polyalkyl methacrylate alkaline earth metal salt in which the alkali metal or the alkaline earth metal is substituted with counter ions by saponification with a metal hydroxide. .

Hereinafter, an electrical resistance type cationic organic polymer humidity sensor according to the present invention will be described with reference to the accompanying drawings.

In the present invention, the polymer is first polymerized with a methacrylic acid alkyl ester as a monomer and then polymerized with a polymethacrylic acid alkyl ester by a general method, and then the polymethacrylic acid alkyl ester is reacted with a hydrogen halide in the presence of an acidic solution to give a hydroxy group an alkyl It was introduced into the ester to synthesize a polyalkylmethacrylic acid having a large molecular weight.

The hydroxy group-introduced polymethacrylic acid alkyl ester is hydrolyzed with a hydroxide of an alkali metal or alkaline earth metal to replace hydrogen of the carboxylic acid portion of the polymethacrylic acid alkyl ester with a counter ion.

1 is a structural diagram of an electrical resistance organic polymer humidity sensor manufactured according to the present invention.

The organic polymer humidity sensor 10 according to the present invention includes a moisture sensitive film 12, an electrode 14 for maintaining electrical contact with the moisture sensitive film 12, an electrode snap 16 for fixing the electrode 14, and an electrode ( And a terminal 18 for connecting 14 to the outside.

At this time, the moisture sensitive film 12 consists of a methyl methacryl acid polymer containing the metal salt which has a structure of following General formula (1) or (2).

[Formula 1]

Wherein R is hydrogen, alkyl having 1 to 18 carbon atoms, branched alkyl, cycloalkyl, hydroxy alkyl, alkoxy alkyl, alkenyl, aryl, arylalkyl, and M is an alkali metal, that is, Group 1 elements on the periodic table.

[Formula 2]

Wherein R is hydrogen, alkyl having 1 to 18 carbon atoms, branched alkyl, cycloalkyl, hydroxy alkyl, alkoxy alkyl, alkenyl, aryl, arylalkyl, and M is an alkaline earth metal, ie, Group 2 elements on the periodic table.

The organic polymer humidity sensor 10 is an alkali metal or alkaline earth metal after introducing a hydroxy group into a polymethacrylic acid alkyl ester, as shown in the general formula 1 or 2, as the moisture absorbent film 12, the impedance of which varies with humidity, as a moisture absorbent. And a polyalkylmethacrylic acid alkali metal salt in which the alkali metal is substituted with a counter ion by saponification with a hydroxide of ions, and an electrode snap including a pair of terminals 18, a platinum electrode 14, and silver-palladium. It is made by depositing the humidity electrode 16) and drying it to form a moisture-sensitive film (12).

The polyalkylmethacrylic acid prepared in the present invention can control the introduction of a hydroxy group to 0 to 100% by changing the reaction time and conditions, preferably introducing a hydroxy group to 60 to 100%. In addition, saponification with an alkali metal hydroxide can also control saponification to 0 to 100% by changing the reaction time and conditions, preferably saponification to 50 to 90%.

Depending on the humidity of the ambient by being to control the amount of poly-acrylic acid alkyl ester with an alkali metal or alkaline earth metal hydroxide, a hydroxy group is introduced in order to control the amount of ions that affect the impedance in the present invention 10 ² to 10 ⁸ It can have impedance in the range of.

The saponification with hydroxides of alkali metals or alkaline earth metals for synthesizing the humectants of the polyalkylmethacrylic acid metal salts can be easily understood by those skilled in the art, and the introduction of hydroxyl groups Solvents used for saponification may also be those used in conventional reactions.

In particular, a protective film may be further formed to protect the moisture-sensitive film coated in the present invention from various external environments such as an organic solvent.

<Example 1 to Example 5>

The polymethacrylic acid alkyl ester was reacted with a hydrogen halide in the presence of an acidic solution to prepare a hydroxide of polyalkylmethacrylic acid and an alkali metal having 100% of a hydroxy group, respectively, 1: 0.5 (Example 1) and 1: 0.6 (Example 2). , 1: 0.7 (Example 3), 1: 0.8 (Example 4), 1: 0.9 (Example 5) and reacted with a polyalkylmethacrylic acid alkali metal salt synthesized by water as a solvent 7% by weight Make solution. A humidity sensor consisting of a pair of terminals 4, a platinum electrode 2, and an electrode snap 3 containing silver-palladium was deposited and dried to prepare a final humidity sensor.

Humidity sensors were manufactured to observe the characteristics by measuring the impedance at 20 ~ 95% RH, the results are shown in Figure 2, it can be seen that the response speed has an excellent response speed as shown in FIG.

<conclusion>

Since the starting material started from a high degree of polymerization, it was possible to manufacture an electrical resistance organic polymer humidity sensor with excellent water resistance and response speed.

As mentioned above, the electrical resistance organic polymer humidity sensor manufactured by the present invention has a good response speed, and can be suitably used in machines and devices requiring humidity measurement such as a humidifier or a dehumidifier.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (4)

A moisture sensitive film 12, an electrode 14 for maintaining electrical contact with the moisture sensitive film 12, an electrode snap 16 for fixing the electrode 14, and a terminal 18 for connecting the electrode 14 to the outside. In the electrical resistance organic polymer humidity sensor 10 comprising a), The moisture-sensitive film 12 polymerizes the methacrylic acid alkyl ester to form a polymethacrylic acid alkyl ester, reacts it with a hydrogen halide in the presence of an acidic solution, introduces a hydroxy group, and alkalis the polyalkylmethacrylic acid into which the hydroxy group is introduced. An electrically resistive organic polymer humidity sensor comprising a polyalkylmethacrylic acid alkali metal salt in which an alkali metal is substituted with a counter ion by saponification with a metal hydroxide. 2. The electrical resistance organic polymer humidity sensor according to claim 1, wherein the polyalkyl methacrylate alkali metal salt is represented by the following general formula (1). [Formula 1] R is hydrogen, alkyl having 1 to 18 carbon atoms, branched alkyl, cycloalkyl, hydroxy alkyl, alkoxy alkyl, alkenyl, aryl, arylalkyl, and M is an alkali metal, that is, a group 1 element on the periodic table. A moisture sensitive film 12, an electrode 14 for maintaining electrical contact with the moisture sensitive film 12, an electrode snap 16 for fixing the electrode 14, and a terminal 18 for connecting the electrode 14 to the outside. In the electrical resistance organic polymer humidity sensor 10 comprising a), The moisture-sensitive film 12 polymerizes the methacrylic acid alkyl ester to form a polymethacrylic acid alkyl ester, reacts it with a hydrogen halide in the presence of an acidic solution, introduces a hydroxy group, and alkalis the polyalkylmethacrylic acid into which the hydroxy group is introduced. An electrically resistive organic polymer humidity sensor comprising a polyalkylmethacrylic acid alkaline earth metal salt in which an alkaline earth metal is substituted with counter ions by saponification with an earth metal hydroxide. 4. The moisture resistance organic polymer humidity sensor according to claim 3, wherein the polyalkyl methacrylate alkaline earth metal salt is represented by the following general formula (2). [Formula 2] Wherein R is hydrogen, alkyl having 1 to 18 carbon atoms, branched alkyl, cycloalkyl, hydroxy alkyl, alkoxy alkyl, alkenyl, aryl, arylalkyl, and M is an alkaline earth metal, that is, a Group 2 element on the periodic table.