JP2010022952A - Agent and sheet for removing aldehyde - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agent and a sheet for selectively and efficiently removing only aldehydes without using activated carbon or impregnated charcoal. <P>SOLUTION: An aldehyde-removing characteristic and suppression of desorption of smell are made compatible by supporting an amino silane on a silica gel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a removal agent and a removal sheet excellent in aldehyde removal performance.

  There are a wide variety of odorous substances contained in the air, and among them, lower aldehydes such as acetaldehyde and formaldehyde are a major problem. Lower aldehydes have many sources such as tobacco smoke and automobile exhaust gas, as well as synthetic resin thermal decomposition. Moreover, since it is perceived as odor or irritation even at a low concentration, removal from the living environment is desired. In general, physical adsorption by activated carbon having a large surface area and pore volume is widely used to remove contaminants in the air, but the effect is insufficient for lower aldehydes having a low boiling point.

  Therefore, as a means for improving the adsorption removal performance of lower aldehyde by activated carbon, for example, a method for improving the performance by attaching amines to activated carbon is disclosed (for example, see Patent Document 1). However, the removal agent and air filter using the technology adsorbs odors other than the target aldehyde by physical affinity (intermolecular force), so that there is a problem of re-release due to changes in temperature and humidity and odor concentration. there were. This is because most of the adsorption capacity of activated carbon is physical adsorption, and the odor component is not stabilized by chemical bonding, so the odor component gradually moves as the adsorption equilibrium moves due to changes in temperature and humidity or odor concentration. It is a phenomenon that occurs because it is released.

  As a means for adsorbing and removing acetaldehyde without using activated carbon, a deodorant composition containing at least one selected from hydrazides, urea and derivatives thereof as an active ingredient has been disclosed (for example, see Patent Document 2). However, this deodorant was designed assuming a static condition and had no practical effect on the removal of acetaldehyde in the dynamic state.

  A filter in which an aldehyde-reactive drug is supported on an inorganic removing agent is disclosed (for example, see Patent Document 3). However, since attention is focused only on the adsorption characteristics of aldehydes and hydrophobic hydrocarbons, it cannot be said that the removal agent composition suitable for the ventilation method, the physical adsorption of hydrophilic compounds, and the release characteristics thereof have been sufficiently studied. Therefore, there has been a problem that a desorption odor from a carboxyl compound having a strong odor intensity cannot be avoided.

Japanese Patent Laid-Open No. 5-317703 Japanese Patent No. 3797852 JP 2008-138300 PR

  An object of the present invention is to provide a removing agent and a sheet material that selectively and efficiently remove aldehydes to be removed and reduce a desorption odor.

That is, the present invention is as follows.
1. An aldehyde remover in which aminosilane is supported on silica gel.
2. ^2. The aldehyde remover according to 1 above, wherein the silica gel has a particle diameter of 0.05 to 5 mm, a pore diameter of 0.1 to 100 nm, and a specific surface area of 20 to 1000 m ² / g.
3. 2. The aldehyde removing agent according to 1 above, wherein the aminosilane is alkoxysilane.
4). The aldehyde remover according to any one of the above 1 to 3, which is applied to reduce the aldehyde concentration in an automobile compartment.
5). The removal sheet formed using the removal agent in any one of said 1-4.

  The removal agent and removal sheet according to the present invention have excellent reaction rate and adsorption capacity with aldehydes, achieve high removal efficiency even under high wind speeds, and reduce off-flavors due to re-release of odorous substances from the removal agent. Can do.

  In the present invention, silica gel is preferably used as the porous carrier. Silica gel is an aggregate of primary particles mainly composed of silicon dioxide, and can be obtained by various methods such as a gas phase method, a wet method (precipitation method), and a sol-gel method. As the silica gel used in the present invention, any silica gel obtained by any method can be preferably used as long as desired characteristics can be obtained.

The silica gel particles used in the present invention preferably have a particle diameter of 0.05 to 5 mm in consideration of aldehyde adsorption capacity and odor desorption characteristics. More preferably, it is 0.1-2 mm, More preferably, it is 0.15-1 mm. When the particle diameter is less than 0.05 mm, it is advantageous for obtaining the adsorption speed, but when used in a ventilated state such as a filter, if the necessary particles are filled to secure the adsorption capacity, the ventilation resistance becomes too large. There's a problem. Further, it becomes difficult to handle the particles and to carry them on the sheet, so that the particles are easily dropped and scattered. On the other hand, if the particle diameter exceeds 5 mm, the collection efficiency as a filter is lowered, and it is difficult to ensure the flexibility of the sheet and the convenience is lowered, which is not preferable.
The particle diameter means a geometric particle diameter that is handled under normal circumstances and exists as a contact surface with a gas at the time of use. Even if it is directly obtained at the time of synthesis, it can be obtained by pulverization and classification. It may be a material formed by molding powdered silica with an inorganic or organic binder, or may be formed by bonding and integration with a thermoplastic or thermosetting resin.

The pore diameter of the silica gel particles is preferably 0.1 to 100 nm, more preferably 1.0 to 75 nm, still more preferably 10 to 60 nm, and most preferably 20 to 50 nm. This is because, when the pore diameter is 0.1 nm or more, the pores are hardly blocked at the time of drug attachment, and the physical adsorption force due to the intermolecular force between the walls can be reduced. On the other hand, it is because the surface area for expressing original deodorizing and adsorption characteristics can be obtained by being 100 nm or less.
The pore diameter defined in the present invention means a peak diameter obtained by the BJH method, and is a value calculated from an adsorption isotherm obtained by a nitrogen adsorption method.

The silica gel particles of the present invention preferably have a specific surface area calculated by the nitrogen adsorption BET method of ²⁰ to 1000 m ² / g, more preferably 35 to 500 m ² / g, and still more preferably 50 to 400 m ^2. / G, most preferably 70 to 300 m ² . This is because by setting it to 20 m ² / g or more, an effective area can be obtained as a reaction field between aminosilane and aldehydes, and a reaction rate with the gas component to be removed can be obtained. Moreover, it is because physical odor adsorption | suction can be suppressed because it is small compared with the activated carbon for general gas adsorption | suction by setting it as 1000 m < ² > / g or less. In particular, in the case of silica gel particles, when the surface area is 300 m ² / g or less, the pore adsorption diameter is increased, so that the physical adsorption action due to intermolecular force is remarkably reduced.

  The removing agent of the present invention is characterized by using aminosilane supported in a state free from elution and volatility in order to develop adsorption performance for lower amines such as acetaldehyde. When aminosilane is arranged as a leaving group, there are chlorosilane, hydroxysilane, alkoxylane, and the like, but preferable ones can be used according to processing conditions. Of these, alkoxysilane is preferred from the viewpoint of ease of handling, and ethoxysilane and methoxysilane are most preferred.

  Any aminosilane is preferably used as long as it has one or more amino groups having reactive activity in the aldehyde. For example, when the leaving group is a methoxy group, N-2- (aminoethyl) -3-aminopropylmethylmethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-amino Examples thereof include propyltrimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane and the like. More preferably N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane and N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane having primary amines Therefore, the removal efficiency can be increased.

The method of aminosilane treatment on silica gel is not particularly limited as long as the desired properties can be obtained. For example, aminosilane is mixed in basic silica sol and supported on the surface of primary particles and dried and solidified. It can be supported by a method in which silica gel is dispersed in water and a solvent and subjected to a coupling reaction with aminosilane, a method in which water and solvent diluted aminosilane are sprayed and applied to silica gel and absorbed.
In this case, it may be supported in the form of particles, and treatment after fixing the particles in the sheet is also a preferred method.

  Conventionally, aminosilane processing on silica gel dispersed in a solution requires an amount of surface hydroxyl group sufficient for the coupling reaction. However, the present inventor has intensively studied to support aminosilane on silica gel. It was found that the amount can be controlled by the amount of aminosilane solution that can be adsorbed on silica gel and its dispersion concentration, and can be supported at any ratio.

  Further, as a result of examining the amount of aminosilane supported and the reaction equivalent of aldehyde, it was found that an amino group that does not contribute to the reaction despite being supported is generated. In order to improve the effective utilization rate, it was found that the adsorption capacity is increased by washing and neutralizing the silica gel before loading the aminosilane, or by treating the aminosilane solution in which a strong base is present together with the amino group.

If the silica gel used in the present invention is obtained, for example, by heating and drying basic sol silica, this treatment can be omitted and it can be said that it is more preferable.
It can also be said that an aldehyde remover in which aminosilane and a basic compound are supported on silica gel is also suitable.
Although it does not restrict | limit especially regarding the base used for this invention, For example, if it is an inorganic substance, a hydroxide, carbonate, hydrogencarbonate, etc. of an alkali metal, an alkaline-earth metal, etc. can be used.
It is also preferable to use an organic compound having basicity. By carrying out this treatment, the amino groups that react with mineral acid components (for example, sulfuric acid and hydrochloric acid), which are strong acids used during silica gel production or washing, are reduced and deactivated, and the aldehyde reaction capacity as a removing agent is increased. It becomes possible. When handling property is considered, it is preferable that it is 8-12 as pH of a removal agent slurry, More preferably, it is 9-11.

The supported amount of aminosilane in the present invention is preferably 1 to 100% by weight, more preferably 2 to 50% by weight, and still more preferably 5 to 25% by weight with respect to the weight of the silica gel particles.
The amount of aminosilane supported so that the coating surface area of the aminosilane and the surface area of the substrate are almost the same is suitable as the reaction rate. For the purpose of increasing the reaction capacity, it is also preferable to increase the amount within the above range.
The supported amount of aminosilane as defined herein is a dry weight excluding volatile components such as chlorine, hydrogen chloride, water, alcohol, etc. generated by the treatment solvent and hydrolysis or condensation reaction.

  The removing agent of the present invention can be used by filling a container such as a box, bag, or net with air permeability and allowing it to stand or be ventilated. However, in order to make better use of the advantages of high adsorption speed and low desorption. Is more preferably used as a sheet shape under ventilation conditions. The method for forming a sheet is not particularly limited, and a conventionally known processing method can be preferably used.

  For example, (1) a wet sheeting method obtained by dispersing remover particles in water together with sheet constituent fibers and dehydrating, (2) an airlaid method obtained by dispersing the remover particles together with sheet constituent fibers in the air, (3) Two or more layers of non-woven fabric or woven fabric, net-like material, film, method of filling a remover between layers, (4) Non-woven fabric, woven fabric utilizing adhesive or base material thermoplasticity, A method of adhering and supporting on a porous surface such as urethane foam, (5) A method of mixing and integrating by kneading into a fiber or resin, (6) A method of crystal growth of the porous body itself from inside a carrier such as a fiber, etc. An appropriate method can be used depending on the application.

  The removal agent and removal sheet of the present invention can be suitably used for air filter applications. Since odor adsorption due to physical adsorption is reduced, it can be suitably used for automotive cabin filter applications in that it can suppress desorption odor due to changes in temperature and humidity and odor concentration particularly when an automobile air conditioner is started.

  As the shape of the air filter, it may be used as it is, but it is preferable to adopt a pleat type or a honeycomb type. When using the pleat type as a direct flow type filter, and when using the honeycomb type as a parallel flow type filter, the contact area of the processing air can be increased to improve the collection efficiency and simultaneously reduce the low pressure loss. it can.

  When used as an air filter, it can be used by laminating with a conventionally known electret sheet, a net or sheet material imparting pleatability, a functional sheet imparting antibacterial properties, antiviral properties, antiallergenic properties, and the like.

The present invention will be described in further detail with reference to the following examples. However, the following examples are not intended to limit the present invention, and all modifications that do not depart from the spirit of the present invention are included in the technical scope of the present invention. . In addition, the measuring method was implemented with the following method.
(1) Nitrogen adsorption isotherm For samples from which volatile components have been removed in advance by heating and depressurization treatment, an automatic specific surface area measuring device Gemini (registered trademark) 2375 manufactured by micromeritics is used, and relative pressure is 0.02 to 0 using nitrogen as an adsorbate. The adsorption isotherm was acquired by the equilibrium method up to .95 and the following analysis was performed.
(2) BET specific surface area The specific surface area was calculated from the nitrogen adsorption isotherm by the BET formula (relative pressure 0.02 to 0.3).
(3) Pore volume The amount of nitrogen adsorbed at a relative pressure of 0.95 was converted to liquid nitrogen to calculate the pore volume.
(4) Pore diameter The pore diameter of silica gel means the peak diameter obtained by the BJH method, and was calculated from the adsorption isotherm obtained by the nitrogen adsorption method.
(5) Acetaldehyde removal ability A flat removal sheet was attached to an experimental duct, and air with a temperature of 25 ° C and a humidity of 50% RH was blown into the duct at a speed of 0.2 m / sec. Furthermore, from the upstream side, acetaldehyde is adjusted so as to have an upstream concentration of 5 ppm, and concentration measurement is performed by the gas chromatogram method on the upstream side and downstream side of the removal sheet (1− (downstream concentration / upstream concentration)) × 100 = removal efficiency (%) was calculated.
(6) Release characteristics of detached odor Acetic acid was used as an indicator of released odor as an aliphatic carboxylic acid component that has strong odor intensity and is felt as a bad odor even at low concentrations.
A flat removal sheet was attached to the experimental duct, and air having a temperature of 25 ° C. and a humidity of 50% RH was blown into the duct at a speed of 0.2 m / sec. Further, from the upstream side, acetic acid was supplied at an upstream concentration of 100 ppm, and continuous ventilation was performed until adsorption equilibrium was reached. The acetic acid supply was stopped from the state of adsorption equilibrium, and the concentration of acetic acid on the downstream side of the removal sheet was measured by an infrared absorption method.

[Example 1]
As inorganic particles, silica gel particles having an average particle diameter of 400 μm, a specific surface area of 750 m ² / g, and a pore diameter of 2.5 nm were used. 3-aminopropyltrimethoxysilane was used as aminosilane, and the aqueous dispersion was absorbed into silica gel at a concentration that gave a 10% by weight carrier, and then dried at 100 ° C. The obtained remover was filled between PP nonwoven fabrics so as to be 220 g / m ^2, and formed into a sheet by thermocompression bonding with a web-like adhesive sheet having a basis weight of 10 g / m ² . The amount of aminosilane diluted water was treated based on the capacity (≈pore volume) that the silica gel used could absorb.

[Example 2]
The same treatment as in Example 1 was performed except that silica gel having a specific surface area of 500 m ² / g and a pore diameter of 9 nm was used to obtain a removal sheet filled with 10 wt% aminosilane-supporting silica and 220 g / m ² .

[Example 3]
The same treatment as in Example 1 was performed except that silica gel having a specific surface area of 300 m ² / g and a pore diameter of 30 nm was used to obtain a removal sheet filled with 10 wt% aminosilane-supporting silica and 220 g / m ² .

[Example 4]
The same treatment as in Example 1 was performed except that silica gel having a specific surface area of 80 m ² / g and a pore diameter of 50 nm was used to obtain a removal sheet filled with 10 wt% aminosilane-supporting silica and 220 g / m ² .

[Example 5]
A silica gel having a specific surface area of 250 m ² / g and a pore diameter of 25 nm was used, and the same treatment as in Example 1 was carried out except that 5 wt% potassium carbonate was added to the coupling treatment liquid. A removal sheet filled with 230 g / m ^{2 of} silica was obtained.

[Comparative Example 1]
A coconut shell activated carbon having an average particle diameter of 400 μm and a specific surface area of 1000 m ² / g was used as a 200 g / m ² filled sheet in the same manner as in Example 1 without being processed.

The aldehyde adsorption characteristics will be described with reference to FIGS.
Compared with the activated carbon of the comparative example 1 from FIG. 1, the silica gel of Examples 1-6 has a clear advantage from a viewpoint of adsorption efficiency and adsorption capacity.
Further, as compared with Example 3 from FIG. 2, in Example 5, the adsorption capacity of aldehyde at the same weight is increased, and the deactivation of amino groups is suppressed by using a basic substance in combination. Presumed.

The acetic acid desorption characteristics will be described with reference to FIG.
Compared with the silica gels of Examples 1 to 6, it can be seen that the activated carbon of Comparative Example 1 releases the adsorbed acetic acid at a high concentration over a long period of time.

  The removal agent and the removal sheet according to the present invention are preferably used for applications that are adsorbed by natural diffusion in a stationary state such as in a car or in a room, and as a more suitable application, in order to clean air in a vehicle such as an automobile or a railway vehicle. Air filters, healthy houses, pet-friendly apartments, elderly entrance facilities, hospitals, office filters, air purifier filters, air conditioner filters, OA equipment intake / exhaust filters, building air conditioner filters, industrial clean rooms It is preferably used as a ventilation state for air filter media such as industrial filters.

It is the graph which showed the time-dependent change of the acetaldehyde removal efficiency in the Example and comparative example of this invention. It is the graph which showed the time-dependent change of the acetaldehyde removal efficiency in the Example of this invention. It is the graph which showed the time-dependent change of the acetic acid rerelease in the Example and comparative example of this invention.

Claims (5)

  An aldehyde remover in which aminosilane is supported on silica gel. The aldehyde remover according to claim 1, wherein the silica gel has a particle diameter of 0.05 to 5 mm, a pore diameter of 0.1 to 100 nm, and a specific surface area of 20 to 1000 m ² / g.   The aldehyde removing agent according to claim 1, wherein the aminosilane is an alkoxysilane.   The aldehyde removing agent according to any one of claims 1 to 3, which is applied to reduce an aldehyde concentration in an automobile compartment.   The removal sheet which uses the removal agent in any one of Claims 1-4.