JP2016193413A - Water-resistant gas adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-resistant gas adsorbent and a gas purification filter which can maintain deodorization performance even under severe environments such as condensation, contact with water droplets, and washing with water.MEANS FOR ACHIEVING THE PURPOSE: A gas adsorbent is obtained by attaching polytetrafluoroethylene with a melting point of 35°C or more and 290°C or less to a porous adsorbent.SELECTED DRAWING: None

Description

  The present invention relates to a water-resistant gas adsorbent and a gas purification filter using the same.

  Conventionally, in gas purification filters that remove odors and harmful gases, porous materials such as activated carbon, silica gel, zeolite, and sepiolite have been used as adsorbents, which are fibrous porous like activated carbon fibers or crushed and molded. It is used as a filter after the container is filled with particles or formed into a sheet shape by combining with a fibrous material.

  The aforementioned porous adsorbents improve the removal efficiency and durability against gaseous substances, so that they are alkaline substances for acidic gases, acidic substances for basic gases, and aldehyde-based gases. It is used by supporting amine compounds.

  These adsorbents and adsorption filters are widely used in places where condensation occurs or raindrops or washing water enters such as air conditioning filters for factories and buildings that introduce outside air, and cabin filters for automobiles. In this case, when water droplets come into contact with the porous adsorbent, there is a problem in that the supported drug is eluted and precipitated, thereby causing corrosion and fouling inside the apparatus and a decrease in adsorption performance.

  Patent Document 1 and Patent Document 2 disclose a filter obtained by forming a sheet containing activated carbon into a pleated shape. However, no consideration is given to the above problem. Patent Documents 3 and 4 disclose filters that focus on drainage and wet shape maintenance, but do not consider deodorization performance or elution problems.

  Patent Document 5 discloses a method of using a water repellent made of an acrylic silicon copolymer for performance degradation due to drug elution. However, since the emulsion resin is used, the performance of the adsorbent is reduced and the pores are blocked. In addition, the surface tension lowering effect indicated by the degree of hydrophobicity is not sufficient, and even if it has an effect on clean water, it is effective against drug elution in the actual use environment such as contamination and detergent. There was a problem that the performance was insufficient.

JP-A-2-135141 JP 2000-24426 A JP 2005-52744 A JP 2012-125714 A JP 2011-206116 A

  An object of the present invention is to provide a water-resistant gas adsorbent and a filter capable of maintaining the deodorizing performance even under a severe environment such as condensation, contact with water droplets, and washing with water.

As a result of intensive studies to solve the above problems, the present inventors have finally completed the present invention. That is, the present invention is as follows.
(1) A gas adsorbent obtained by adhering polytetrafluoroethylene having a melting point of 35 ° C. or higher and 290 ° C. or lower to a porous adsorbent.
(2) The gas adsorbent according to (1), wherein the porous adsorbent is attached with a chemical agent.
(3) A gas purification filter using the gas adsorbent according to (1) or (2).

  The gas adsorbent of the present invention provides a water-resistant gas adsorbent and a gas purification filter using the same that can maintain the deodorizing performance even under severe environments such as condensation, contact with water droplets, and washing with water. be able to.

  In the present invention, a porous adsorbent is used in order to provide a gas adsorption function. The shape of the porous adsorbent is not particularly limited, and it can be preferably used even if it is powdery, granular, fibrous, or molded from these.

  The porous adsorbent is not particularly limited and preferably used as long as it can exhibit a gas adsorbing function, such as inorganic materials such as activated carbon, zeolite, silica gel, sepiolite, and organic materials such as MOF, COF, and styrenedivinylbenzene. be able to. About these, it is also preferable to raise hydrophobicity beforehand using a silane coupling process etc.

  In the present invention, it is preferable to use the porous adsorbent alone or a drug having a gas adsorbing function attached to the porous adsorbent. Specifically, for aldehyde gases, nitrogen compounds such as NOx, sulfur compounds such as SOx, and acidic substances such as acetic acid, amines such as ethanolamine, polyethyleneimine, aniline, p-anisidine, sulfanilic acid, etc. Drugs and adipic acid dihydrazides, sodium hydroxide, potassium hydroxide, guanidine carbonate, guanidine phosphate, aminoguanidine sulfate, 5,5-dimethylhydantoin, benzoguanamine, 2,2-iminodiethanol, 2,2,2- Nitrotriethanol, ethanolamine hydrochloride, 2-aminoethanol, 2,2-iminodiethanol hydrochloride, p-aminobenzoic acid, sodium sulfanilate, L-arginine, methylamine hydrochloride, semicarbazide hydrochloride, hydrazine, hydroquinone, Hydroxyl sulfate Permanganate, potassium carbonate, potassium hydrogen carbonate and the like are preferably used. For basic polar substances such as ammonia, methylamine, trimethylamine and pyridine, for example, phosphoric acid, citric acid, malic acid, Ascorbic acid or the like is preferably used.

  In the present invention, the chemical loading treatment on the porous adsorbent can use a conventionally known method, for example, a solution with an organic solvent, water, etc., which is sprayed on the porous body or immersed in the solution. For example, a method obtained by drying and adsorbing with a porous material, or a method of melting and absorbing by heating above the melting point of the drug in contact with the porous body can be used.

  The drug carrying treatment may be performed after the polytetrafluoroethylene treatment described below or before the treatment. In consideration of the permeability of the solution and the drug, the drug loading process is preferably after the polytetrafluoroethylene process.

  The present invention is characterized in that polytetrafluoroethylene having a melting point of 35 ° C. or higher and 320 ° C. or lower is supported on at least a part of the porous adsorbent. The reason for using fluorine-based materials is not only to give high water repellency to clean water, but also to suppress penetration of water containing hydrocarbon surfactants and contaminants. This is because. The melting point of polytetrafluoroethylene is preferably 60 ° C. or higher and 315 ° C. or lower, more preferably 80 ° C. or higher and 300 ° C. or lower, and further preferably 100 ° C. or higher and 290 ° C. or lower. If it is the said range, it may have distribution in molecular weight, and even if it is a molecule | numerator of single structure, it can use preferably.

The reason why polytetrafluoroethylene having the above melting point is used is as follows: (1) When the high molecular weight is such that the melting point exceeds 320 ° C., the melt viscosity is high and difficult to coat; (2) When the processing temperature is high, the carrier (Especially synthetic polymer) has problems of deterioration and heat resistance, and (3) low melting point polytetrafluoroethylene used in the present invention as compared with general polytetrafluoroethylene (surface tension: 17.5 mN / m). Fluoroethylene (surface tension: 13 to 17.5 mN / m) has a small surface tension and a high oil repellency effect due to its crystal form and CF ₃ group terminal density, and (4) when epitaxial growth is used, a regular structure of crystalline molecules Accordingly, to express the minimum surface tension (6 mN / m) in the plane on the molecules CF ₃ group has, (5) the molecular weight be capable small grinding process, 6) Boiling point within the practical temperature range, PVD treatment is possible by heating under normal pressure, reduced pressure, and vacuum conditions. (7) Plasma treatment that makes it difficult to control the molecular weight and structure of attached components. Unlike (fluorinated fluorinated), it is advantageous from the viewpoint of PFOA and PFOS regulation, (8) It has crystallinity, and hence the oil repellency change due to the change of molecular orientation is suppressed, (9) Polar functional group No oil repellency change due to oil type because it does not have (10) Self-adhesiveness by heat treatment because it has a melting point, (11) Fluorine-based that general polytetrafluoroethylene does not have Examples include solubility in a solvent. In addition, general fluorine-based acrylate processing agents contain emulsifiers and film-forming aids, and short chain perfluoro groups of C ₆ F ₁₃ or lower are used as side chains in order to comply with PFOA and PFOS regulations. This is because it has a problem that it has a high molecular weight but is sticky and easily closes the pores.

  The processing method used in the present invention utilizing the above characteristics is as follows: (1) Mixing a predetermined powdered polytetrafluoroethylene powder with a porous adsorbent and performing a heat treatment at a temperature equal to or higher than the melting point of polytetrafluoroethylene. (2) A method of immobilizing by dispersing in a predetermined powdered tetrafluoroethylene gas stream and infiltrating the carrier surface and inside, followed by heat treatment above the melting point of fluoroethylene, (3) (4) a predetermined method in which a predetermined powdered tetrafluoroethylene is dispersed in a liquid, applied and penetrated into a carrier, the liquid is dried and removed, and heat treatment is performed at a temperature equal to or higher than the melting point of polytetrafluoroethylene; Polytetrafluoroethylene is evaporated at a temperature not lower than the melting point and not higher than the thermal decomposition temperature, and then cooled and solidified on the support. If necessary, the melting point is higher than the melting point of polytetrafluoroethylene. A method of fixing by heat treatment, and (5) a method of fixing a predetermined polytetrafluoroethylene to a support by a sputtering method, and if necessary, performing a heat treatment at a temperature equal to or higher than the melting point of polytetrafluoroethylene. (6) A predetermined polytetrafluoroethylene is dissolved in a solvent, applied to a substrate, sprayed, and immersed, and then the solvent is removed, and if necessary, it is melt-fixed by performing a heat treatment at or above the melting point of polytetrafluoroethylene. A method, etc. can be illustrated. These methods may be used alone or in combination.

  The porous adsorbent of the present invention can be used alone as a packed bed or a fluidized bed, or can be used as a molded body using compression molding or a binder. In addition, as a filter application, use a method of mixing with fiber to form a sheet, a method of sandwiching between fiber sheets, a fiber sheet surface, a film, a metal foil surface, processing into a flat plate or a honeycomb shape if necessary Can do.

  Further, the present invention can be widely used in a humid environment where condensation occurs in accordance with the gist of the present invention, an environment where raindrops containing contaminants or washing water containing a surfactant are mixed, or a filter used for washing.

(Water resistance test)
10 g of purified water is added to 1 g of the porous adsorbent and left for 10 minutes while gently shaking. By separating water and the adsorbent by filtration, the elution rate of the drug or the pH of the solution is measured.

(Washing resistance test)
10 g of purified water and 0.015 g of sodium lauryl benzene sulfonate are added to 1 g of the porous adsorbent, and left for 10 minutes while gently shaking. By separating water and the adsorbent by filtration, the elution rate of the drug or the pH of the solution is measured.

[Example 1]
5% by weight was supported by spraying and drying phosphoric acid in an aqueous solution onto coconut shell activated carbon having an average particle diameter of 250 μm. The obtained phosphoric acid-impregnated activated carbon was placed on a sieve, and further placed on a metal dish on which Central Glass Co., Ltd. low molecular weight polytetrafluoroethylene: cephalal lube V (melting point 250-270 ° C.) was allowed to stand. Heated to 250 ° C. and cooled to room temperature. The adhesion amount to the activated carbon as the carrier was 3% by weight. The solution pH in the water resistance test was 6.8, and the solution pH in the wash resistance test was 7.1, which was the same value as the blank.

[Example 2]
An adipic acid dihydrazide as an aqueous solution was sprayed and dried on C-type silica gel having an average particle diameter of 250 μm to carry 10% by weight. A 2% solution of polytetrafluoroethylene of nC ₁₈ F ₃₈ (melting point: 167 ° C.) was adsorbed and dried on the souplion manufactured by Dupont on the obtained silica gel with adipic acid dihydrazide. The amount of adhesion to the silica gel carrier was 1.5% by weight. The dissolution rate of adipic acid dihydrazide after the water resistance test was 2%, and the dissolution rate after the cleaning resistance test was 5%.

[Example 3]
An adipic acid dihydrazide as an aqueous solution was sprayed and dried on C-type silica gel having an average particle diameter of 250 μm to carry 10% by weight. N-C ₁₂ F ₃₀ (melting point: 76 ° C.) polytetrafluoroethylene powder was mixed with the obtained adipic acid dihydrazide-added silica gel and mixed at 100 ° C. for 10 minutes. The amount of adhesion to the silica gel carrier was 7% by weight. The dissolution rate of adipic acid dihydrazide after the water resistance test was 0%, and the dissolution rate after the cleaning resistance test was 2%.

[Comparative Example 1]
The same treatment as in Example 1 was performed except that the polytetrafluoroethylene treatment was not performed. The solution pH in the water resistance test was 3.2, and the solution pH in the wash resistance test was 3.4.

[Comparative Example 2]
The same treatment as in Example 2 was performed except that the polytetrafluoroethylene treatment was not performed. The elution rate of adipic acid dihydrazide after the water resistance test was 96%, and the elution rate after the cleaning resistance test was 93%.

[Comparative Example 3]
An adipic acid dihydrazide as an aqueous solution was sprayed and dried on C-type silica gel having an average particle diameter of 250 μm to carry 10% by weight. The obtained adipic acid dihydrazide-attached silica gel was sprayed with an acrylic emulsion, Vinibran 2647-10% diluted solution manufactured by Nissin Chemical Industry Co., Ltd., and dried. The elution rate of adipic acid dihydrazide after the water resistance test was 12%, and the elution rate after the cleaning resistance test was 86%.

  From Example 1 and Comparative Example 1, it can be seen that the adsorbent of the present invention suppresses elution of acidic components. From Examples 2 and 3 and Comparative Example 2, it can be seen that the adsorbent of the present invention has both water resistance and washing resistance. Moreover, although it has water resistance regarding the comparative example 3, it turns out that elution arises in the wash water containing surfactant etc.

  According to the present invention, a water-resistant gas adsorbent and a gas purification filter capable of maintaining deodorization performance even under severe environments such as condensation, contact with water droplets, and washing with water can be obtained. It is.

Claims (3)

  A gas adsorbent obtained by adhering polytetrafluoroethylene having a melting point of 35 ° C. or higher and 290 ° C. or lower to a porous adsorbent.   The gas adsorbent according to claim 1, wherein the porous adsorbent is attached with a chemical agent.   A gas purification filter using the gas adsorbent according to claim 1.