JP2007296058A - Deodorization honeycomb - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart flame retardancy and water resistance by a simple method, to improve productivity and to reduce the emission amount of harmful substances relating to a deodorization honeycomb for the purpose of removing odors. <P>SOLUTION: (1) The deodorization honeycomb in which an absorbent and/or a catalyst is deposited on a honeycomb base material composed of an inorganic material is characterized by using the mixture of water-based resin emulsion and inorganic colloid as a binder, (2) the deodorization honeycomb in (1) is characterized by that the absorbent is active carbon, and (3) the deodorization honeycomb in (1) is characterized by using the active carbon and a metal catalyst together. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a deodorizing filter for removing odors and harmful substances contained in a gas, and more specifically, deodorizing property is expressed by an adsorbent and / or a catalyst supported on an inorganic material by a binder substance, In addition, the present invention relates to a deodorized honeycomb having water resistance and flame retardancy.

  Conventionally, studies have been made to remove odorous components in gas. For example, deodorizing apparatuses using excited active species generated by high-voltage discharge have been used in air conditioners, dedicated deodorizing apparatuses, and the like. Such deodorizers are not effective enough for low-reactivity substances such as hydrocarbons alone, and adsorbents such as activated carbon and metal catalysts are used in combination to adsorb or decompose and remove by-products. Generally used. And, as the adsorbent, a structure having a honeycomb shape is often used from the viewpoint of reducing ventilation resistance. Since such a honeycomb is installed side by side with the discharge device, it is preferable to have flame retardance in order to ensure safety during use. For example, flame retardancy specified by UL (Underwriters Laboratories Inc.) Standards are widely applied mutatis mutandis.

  Until now, halogen compounds containing chlorine, bromine, etc., phosphate ester compounds containing phosphorus element, etc. have been used to suppress combustibility, but these have been reduced or eliminated due to sick house and dioxin problems in recent years. Is required.

  Further, in recent years, it has been desired to provide water-washing water resistance capable of removing contaminants by water immersion in order to reduce the replacement frequency and facilitate maintenance. Until now, various deodorized honeycombs have been proposed, but have the following problems in order to satisfy the demands of flame retardancy and water resistance.

  For example, there has been proposed a deodorized honeycomb obtained by using kraft paper or cardboard base paper having no flame retardancy as a honeycomb-shaped base material and coating a catalyst material and activated carbon with a colloidal compound such as silica sol (for example, Patent Document 1). reference). However, when a non-flammable material is used as the base material, it is necessary to increase the ratio of the colloidal compound to satisfy the flame retardancy, resulting in a problem in the basic characteristics as a deodorizing filter. In addition, there is a problem that water resistance and moisture resistance cannot be obtained when sintering is not performed.

Moreover, the method of carrying | supporting activated carbon using an emulsion binder with respect to an inorganic fiber sheet is disclosed (for example, refer patent document 2). However, in such a method, in order to obtain a honeycomb shape after creating a planar sheet, it is necessary to give the sheet material flexibility, and therefore, it is necessary to add a flame retardant to reduce honeycomb combustibility. Become. In addition, a flame retardant that can be added in an aqueous system elutes by water immersion, making it difficult to maintain flame retardancy.

  In addition, a filter has been proposed in which an aluminum thin plate is used as a base material, corn starch or PVA is used as a binder, and an ozonolysis catalyst is applied on the base material (see, for example, Patent Document 3). However, since a water-soluble polymer is used as a binder, it does not have water resistance.

  Furthermore, a method of directly supporting a catalyst compound from an aqueous solution of a metal salt using an inorganic fiber aggregate such as ceramic fibers as a supporting substrate for an ozonolysis catalyst has been proposed (for example, Patent Document 4). However, there are problems in that it is difficult to obtain a desired loading amount and catalytic activity, and an odor is likely to occur because an adsorbent cannot be used in combination.

  Further, a gas adsorbing sheet characterized by containing at least a metal oxide, a hardly soluble flame retardant, and an organic binder in the gas adsorbing layer is disclosed (for example, Patent Document 5). However, since water-based polymers are used as the organic binder, water resistance is poor, and it is necessary to maintain flexibility for processing in a sheet state, and it is difficult to apply the adsorption layer. is there.

Further, a deodorized honeycomb that does not require a sintering process by mixing and extruding a metal oxide catalyst, aluminum hydroxide, and a binder is disclosed (for example, Patent Document 6). However, water resistance cannot be imparted because a water-soluble polymer is used as a binder.
JP-A-5-309232 JP-A-1-293136 JP-A-2-273512 JP-A-1-245850 Japanese Laid-Open Patent Publication No. 2003-47820 JP-A-10-272358

  The present invention has been made against the background of the above-described prior art, and is a deodorized honeycomb provided with an adsorption and decomposition layer on a honeycomb substrate made of an inorganic material, imparting water resistance only by impregnation drying, Another object of the present invention is to provide a deodorized honeycomb capable of imparting flame retardancy without adding low molecular halides and phosphate esters.

  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 (1) a deodorizing honeycomb in which an adsorbent and / or a catalyst is supported on a honeycomb substrate made of an inorganic material, wherein a mixture of an aqueous resin emulsion and an inorganic colloid is used as a binder. (2) The deodorizing honeycomb according to (1), wherein the adsorbent is activated carbon, and (3) the deodorizing honeycomb according to claim 1, wherein the activated carbon and a metal catalyst are used in combination. is there.

Hereinafter, the present invention will be described in detail.
The deodorizing honeycomb of the present invention preferably uses a honeycomb substrate made of an inorganic material. That is, the honeycomb substrate made of an inorganic material can increase the ratio of the combustible material as compared with the honeycomb material using the organic fiber or the combustible substrate, and therefore, the deodorization which is an original function. This is because flame retardancy can be imparted while maintaining performance. And since it becomes possible to mix the halogen-free resin emulsion which is a combustible substance, there exists an advantageous effect that water resistance improves.

  This inorganic material is preferably made of metal, silica, alumina, glass, artificial fibers such as rock wool, natural mineral fibers such as sepiolite and attapulgite, and metals such as aluminum, iron, copper and stainless steel. The thing made into thin plate shape is mentioned. In addition, any sheet material made of the above-described materials can be used as long as it can be applied as a honeycomb without depending on a manufacturing method such as nonwoven fabric, woven fabric, papermaking, and compression molding. In order to improve water resistance and strength, it is also preferable to treat with an inorganic binder having curability before molding and / or after molding.

  Sheet material made of inorganic material is processed into a honeycomb shape and used. However, as long as a planar structure parallel to the gas flow direction can be obtained, the honeycomb has a hexagonal cross section, square, sinusoidal waveform, roll It can be used as a required shape such as a shape in which a hollow column such as a hollow polygonal column or a hollow cylinder is continuously formed. For example, in order to make a sheet material made of an inorganic material into a sinusoidal honeycomb shape, first, the gas adsorbing sheet is passed through a shaping roll and shaped into a corrugated shape, and the sheet is flat on one or both sides of the corrugated gas adsorbing sheet. Join. This is laminated to form a sinusoidal honeycomb filter.

  In the present invention, a gas adsorption decomposition layer is formed on at least a part of a honeycomb substrate made of an inorganic material. As a specific method, activated carbon and binder are mixed with a small amount of dispersing / thickening agent as necessary to form an aqueous paste, and then the paste is immersed, sprayed, poured onto the substrate surface by pouring, etc. It can be obtained by removing excess paste by centrifugation, compressed air, suction, etc. and drying.

  In the gas adsorption honeycomb of the present invention, it is preferable to use a physical adsorbent such as activated carbon and zeolite and / or a metal catalyst and / or a composite thereof in the adsorption layer.

The activated carbon that is preferably used is not particularly limited as long as it is obtained by carbonization activation of various materials. For example, wood (charcoal), sawdust, fruit shells (coconut shells, rice husks, coffee beans, etc.) ), Plant materials such as cellulose, lignin and pulp; mineral materials such as lignite, lignite, peat, anthracite, and petroleum sludge as raw materials, chemical activation using zinc chloride or gas activation using steam, etc. The specific surface area of the activated carbon used in the present invention is at least 300 m ² / g or more, preferably 500 m ² / g or more, more preferably 1000 m ^{2 in} the powder state before processing. / G or more. This is to maintain the deodorizing performance even when the pores are blocked by the binder component

  The zeolite used in the present invention can be appropriately selected depending on the target odor, and can be selected from the viewpoints of pore diameter, silica-alumina ratio, specific surface area, and the like. In particular, when used as a deodorizing application, it is more preferable to use a hydrophobic zeolite having a high silica component content ratio.

  As the metal catalyst used in the present invention, a base metal oxide typified by manganese oxide, iron oxide, copper oxide or the like, a noble metal catalyst typified by platinum or the like is preferably used depending on the application.

  As those having both physical adsorption ability and catalytic ability, a catalyst-supporting adsorbent in which metal particles are deposited on the surface or inside pores of activated carbon, zeolite, activated alumina or the like can be preferably used.

  The shape of the adsorptive decomposition agent (and its composite) may be powdery or fibrous, but is preferably powdery for use as an aqueous paste, with an average particle diameter of 0.2 to 100 μm is preferable, more preferably 0.4 to 50 μm, and most preferably 0.5 to 30 μm. When the particle size is less than 0.2 μm, aggregation and solidification are likely to occur, and redispersion in an aqueous paste is difficult. On the other hand, when the thickness exceeds 100 μm, there is a problem in dispersion stability as a paste, and the obtained coating layer tends to have a low density and is likely to fall off due to external force. In addition, the average particle diameter of activated carbon and a catalyst refers to a weight median diameter.

The deodorizing honeycomb of the present invention preferably uses a mixture of an aqueous resin emulsion and an inorganic colloid as a binder. Water-based resin emulsions are excellent in low-temperature adhesiveness, water resistance, and flexibility, but have a large particle size of about 100 nm to 10 μm, and therefore tend to be inferior in adhesion retention with fine particles used as an adsorptive decomposing agent. Since the flow characteristics are likely to change depending on the rate, there is a problem that the film formability is deteriorated when a water-absorbent sheet such as an inorganic fiber sheet is used as the honeycomb substrate. Moreover, since it is comprised from the resin component which has a hydrocarbon as a main component, itself has combustibility.

On the other hand, inorganic colloids are small in particle size with respect to the supported substance and have good dispersibility. Also, since the particles themselves are rigid bodies, fine pores are retained even when the surface of the adsorptive decomposition agent is coated. There is an advantage that the performance is hardly lowered. Moreover, since there is no combustibility of itself in the normal atmosphere, combustion propagation can be suppressed by preventing contact between organic substances. However, since the film obtained by drying and solidification depends on the cohesive force between molecules, it is necessary to conduct a dehydration reaction at a temperature of about 200 ° C. in order to provide adhesive strength, water resistance and moisture resistance. . Furthermore, since it is made of an inorganic material, there is a problem that impact strength and adhesion strength with an organic substance are weak.

  And this inventor discovered that combustibility could be reduced and adhesiveness and water resistance could be improved by using together an aqueous resin emulsion and an inorganic colloid. That is, when the water-based resin emulsion and the inorganic colloid are used in combination, the flammability is reduced while suppressing the deodorization performance deterioration due to pore clogging, and further the film strength is obtained by evaporating water as a dispersion medium. In addition, there is an advantageous effect that the deterioration of the catalyst and the catalyst can be suppressed and the catalyst can be produced with a simple apparatus.

  As the resin emulsion used in the present invention, an aqueous solvent in which fine particles such as acrylic, acrylic-styrene, vinyl acetate, and ethylene-vinyl acetate are suspended and stabilized can be preferably used. In particular, it is most preferable to use an acrylic emulsion having high water resistance and containing no halide. Further, in order to increase the film hardness and suppress the adhesiveness and moisture absorption, the glass transition temperature of the resin component is preferably −20 ° C. or higher, more preferably 0 ° C. or higher, and most preferably 20 ° C. or higher.

  The inorganic colloid used in the present invention is a dispersion in which an inorganic oxide having a particle size of about 1 nm to 100 nm is dispersed in a solvent containing water as a main component. It is a thing which gives. Specifically, colloidal silica, colloidal alumina, colloidal titanium, and the like are selected according to required properties such as particle diameter, shape, and liquidity (acid, alkali). In addition, the particle diameter of a colloid is a number average diameter.

  The gist of the present invention is as described above, but it is also preferable to mix some water-soluble polymer or inorganic mineral in order to adjust the fluidity and viscosity of the slurry and to suppress sedimentation. Examples of water-soluble polymers include MC (methyl cellulose), CMC (carboxymethyl cellulose), polyacrylic acid, alginic acid, lignin sulfonic acid, and alkali metal salts and guar gum, gum arabic, and polyvinyl alcohol. Sepiolite is used as an inorganic material. Swellable clay minerals such as fibrous minerals such as attapulgite and bentonite. However, increasing the amount of addition causes a decrease in moisture resistance and water resistance and an increase in combustibility with water-soluble polymers, so the dry weight ratio in the adsorption layer is 10% or less, more preferably 5% or less, most preferably. Is 3% or less.

  In addition, by using the configuration of the present invention, it is possible to impart flame retardancy even in the configuration of only the adsorbent and the binder, but in order to impart higher flame retardancy, if necessary, aluminum hydroxide, It is also preferable to add a water-insoluble flame retardant such as melamine. This is because such a material maintains the particle shape even in the slurry, and it is difficult to cause degradation of the adsorptive decomposition agent and surface coating. Moreover, since it does not elute at the time of water immersion, a flame retardance can be maintained at the time of water washing.

Hereinafter, the working effects of the present invention will be described more specifically by way of examples. However, the following examples are not intended to limit the method of the present invention, and any design changes in accordance with the purpose described above and below It is included in the technical scope of the invention. Unless otherwise specified, “parts” described in Examples and Comparative Examples represent “parts by weight”.
Each item was evaluated by the following method.

[Flame Retardancy] Evaluation was made based on the UL94V test method defined by UL (Standard for Test for Flameability of Plastic Materials for Parts in Devices and Appliances. Vertical Burning Test; 94V-0, 94V-1, 94V-2). And the combustibility grade was calculated | required from the flammable combustion time and flameless combustion time defined by UL94 test method, and it determined based on the defined reference | standard.

[water resistant]
The honeycomb material provided with the deodorizing layer was immersed in ion-exchanged water for 24 hours and then pulled up from the water and observed.

  (Example 1): A ceramic paper (silica alumina paper) having a thickness of 200 μm was formed into a single cardboard sheet having a height of 2.5 mm and a pitch of 4.1 mm using a corrugating machine. The single-stage cardboard sheets were stacked in 40 stages and cut to obtain a honeycomb substrate having a size of 100 mm × 100 mm and a thickness of 5 mm. As a result of the test based on UL94, the combustion duration of the single sheet was 0 seconds and flame retardancy of V-0.

  To this filter, 10 parts of activated carbon having an average diameter of 15 μm, 10 parts of colloidal silica having a solid content of 20% and 2 parts of an acrylic emulsion having a solid content of 45% were mixed to form a paste. The paste was supported on the honeycomb substrate, and the moisture was dried at 100 ° C. The solid content was 150 g / l and the adsorbent ratio was 78%. As a result of the test based on UL94V, the flame retardancy of the laminate was V-0 flame retardance.

  (Comparative Example 1) Using a honeycomb base material equivalent to that in Example 1, the binder was changed to only 15 parts of colloidal silica, so that processing was carried out so as to obtain an equivalent loading amount and an equivalent adsorbent ratio. As a result of the test based on UL94, flame retardancy of V-0 was obtained, but the adsorbent layer dropped out due to water immersion.

  (Comparative Example 2) Using a honeycomb substrate equivalent to that in Example 1, processing was carried out so as to obtain an equivalent solid content by changing the binder to only 7 parts of the acrylic emulsion. The adsorbent layer was retained even in water immersion, but as a result of the test based on UL94, the combustion time exceeded 60 seconds and the V standard could not be met.

  (Comparative Example 3) Using a honeycomb substrate equivalent to that in Example 1, processing was carried out so as to obtain an equivalent loading amount by changing the binder to only 1 part of sodium alginate. Adhesiveness was good, but the adsorbent layer was dissolved by water immersion, and as a result of a test based on UL94, the burning time exceeded 60 seconds and the V standard could not be met.

  (Comparative Example 4) A honeycomb pulp paper having a thickness of 200 µm was used as a honeycomb substrate, and a honeycomb having the same shape as in Example 1 was prepared and processed with an equivalent paste. As a result of the flammability test, the burning time exceeded 60 seconds and the V standard could not be met.

  Although the honeycomb of Comparative Example 1 using only an inorganic colloid as a binder can impart flame retardancy, it cannot satisfy water resistance.

  Although the honeycomb of Comparative Example 2 using only the acrylic emulsion as the binder has water resistance, it cannot satisfy the flame retardancy.

  In Comparative Example 3 using only a water-based polymer as a binder, both water resistance and flame retardancy cannot be satisfied.

  In the honeycomb of Comparative Example 4 using normal paper as the base material, it is possible to impart water resistance by the paste composition, but it cannot satisfy the flame retardancy.

  The deodorizing honeycomb of the present invention carries an adsorptive decomposition agent on a honeycomb made of an inorganic material, and by using an inorganic colloid and an organic emulsion in combination as a binder, flame retardancy can be achieved without using halogen or phosphate ester flame retardants. It has water resistance by a simple manufacturing method. Further, since an aqueous dispersion medium is used, low-temperature processing is possible, and it becomes possible to obtain a honeycomb filter with improved work environment and reduced VOC emission from the product.

Claims (3)

A deodorizing honeycomb having an adsorbent and / or a catalyst supported on a honeycomb substrate made of an inorganic material, wherein a mixture of an aqueous resin emulsion and an inorganic colloid is used as a binder. The deodorizing honeycomb according to claim 1, wherein the adsorbent is activated carbon. The deodorized honeycomb according to claim 1, wherein activated carbon and a metal catalyst are used in combination.