JP2008228762A - Sound absorptive dust removing filter and cleaner using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound absorptive dust removing filter provided with a dust removing (dust collecting) function for highly efficiently catching allergen substances and a sound absorbing function capable of expecting a high sound absorption effect. <P>SOLUTION: The sound absorptive dust removal filter comprises: an air permeable case 5; at least two or more porous structures 2 housed in it in a vibratable state and provided with continuous meso holes; and a filter 3 for catching floating substances provided on a part of the case 5. Thus, floating allergen substances such as dust, pollen and mites are highly efficiently caught by the filter 3, the energy of sound is converted to heat energy when the sound passes through the porous structures 2 provided with the continuous meso holes, conversion to the heat energy is advanced further by the porous structures 2 which receive the energy of the sound vibrating and rubbing with each other to generate the sound absorption effect, and the dust removing (dust collecting) function and the sound absorbing function are obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a function of collecting allergen substances such as floating dust, pollen and mites, a sound absorbing dust removing filter having a sound absorbing function, and a vacuum cleaner using the same.

  Conventionally, glass wool, rock wool, felt that is an aggregate of fibers, polyurethane foam, etc. have been used as general sound-absorbing materials, but fibrous strips and porous strips were molded. A sound-absorbing molded body is also known (for example, see Patent Document 1). In this method, for example, cellulose acetate fibers and polyurethane foam are put into a container having a desired shape, and a molded body is produced by compression molding. And since the shape of a fiber and a porous body (for example, polyurethane foam) is disperse | distributed randomly rather than uniformly, and the absorption capability of a sound wave energy is improved, it is set as the sound-absorbing molded object with high sound absorption performance.

Moreover, what provided the sound absorption part in a part of filter of the air conditioner is also known (for example, refer patent document 2). This is a filter in which a sound absorbing function is applied by applying, for example, a sound absorbing paint to one of the inclined surfaces of the pleated filter.
JP 2004-163510 A JP-A-8-159509

  However, glass wool, felt, foamed polyurethane, etc., which are common sound absorbing materials, are not realistic because the pressure loss becomes very large when ventilated, and allergen substances such as floating dust, pollen, mites, etc. It was difficult to process the filter to be collected. In addition, it is difficult to add a function of collecting allergen substances such as floating dust, pollen, and mites with high efficiency even in a sound-absorbing molded body. Further, in the filter to which the sound absorbing function is added, since half of the filter has no sound absorbing effect, a high sound absorbing effect cannot be expected.

  The present invention solves the above-mentioned conventional problems, and is a dust removal function that collects allergen substances such as floating dust, pollen, and mites with high efficiency, and a sound absorption function that can be expected to have a high sound absorption effect. An object of the present invention is to provide a sound-absorbing dust filter and a vacuum cleaner using the same.

  In order to solve the above-described conventional problems, a sound absorbing dust removing filter and a vacuum cleaner equipped with the sound absorbing dust filter according to the present invention include a case having air permeability, and at least two mesopores continuously accommodated in a vibrable state. And a filter for collecting suspended solids provided in a part of the case.

  This makes it possible to collect dust, pollen, mites, and allergen substances floating with a filter for collecting suspended substances with high efficiency, and when sound passes through a porous structure having continuous mesopores. The sound energy is converted into heat energy, and the porous structure that receives the sound energy vibrates and rubs against each other, so the conversion to heat energy progresses and produces a sound absorption effect, and the dust removal (dust collection) function A sound absorbing function can be obtained.

  The sound absorbing dust removing filter of the present invention and the vacuum cleaner using the same are a dust removing function for collecting allergen substances such as floating dust, pollen and mites with high efficiency, and a sound absorbing function which can be expected to have a high sound absorbing effect. Have

  According to a first aspect of the present invention, there is provided a case having air permeability, a porous structure having continuous mesopores accommodated in at least two in a vibrable state therein, and a floating substance collection provided in a part of the case A sound-absorbing dust-removing filter provided with a filter. This makes it possible to collect dust, pollen, mites, and allergen substances floating with a filter for collecting suspended substances with high efficiency, and when sound passes through a porous structure having continuous mesopores. The sound energy is converted into heat energy, and the porous structure that receives the sound energy vibrates and rubs against each other, so the conversion to heat energy progresses and produces a sound absorption effect, and the dust removal (dust collection) function A sound absorbing function can be obtained.

  The second invention realizes a sound-absorbing dust removal filter that can collect allergen substances such as dust, pollen, and mites that float more efficiently, particularly by using a HEPA filter in the first invention. it can.

  The third invention is the porous structure in which the porous structure is pushed away even when the sound absorption dust filter continues to be ventilated, particularly when the representative diameter of the porous structure is 1 mm or more in the first invention. Since there is no large gap between them, it is possible to realize a sound-absorbing dust removing filter whose sound-absorbing efficiency does not decrease even if ventilation is continued.

  According to a fourth invention, in particular, in any one of the first to third inventions, the porous structure includes a gelling step of forming a wet gel by mixing a solvent containing at least water and a gel raw material. And a water removal step for removing water in the wet gel and a drying step for obtaining a porous structure by removing the solvent remaining in the wet gel removed in the water removal step. A highly efficient porous structure can be easily produced, and a sound-absorbing dust removing filter with high sound-absorbing efficiency can be realized.

  In the fifth invention, in particular, in the fourth invention, in the gelation step, the gel raw material is a monomer or oligomer of alkoxysilane, and at least the solvent contains water, an alcohol, and an alkali catalyst that promotes gelation. Thus, since the porous structure can be more easily produced, it is possible to realize a sound absorption dust removing filter with high sound absorption efficiency.

The sixth invention has a hydrophobization step before the water removal step, particularly in the fourth invention, wherein R and R ′ represent an alkyl group, and x is 1 to 3 Any integer and hydrophobizing at least a portion of the wet gel surface using an alkylalkoxysilane represented by _Rx (R'O) _4- xSi, and a drying step wherein the at least a portion of the surface is Select a suitable solvent for the hydrophobization step and the drying step by drying at a temperature and pressure conditions below the critical point of the main solvent contained in the hydrophobized wet gel. Thus, a porous structure having high sound absorption efficiency can be produced at low cost without using supercritical drying, and a sound absorption dust removing filter with high sound absorption efficiency can be realized at low cost.

  In the seventh invention, in particular, in the sixth invention, since R and R ′ are both methyl groups and x = 2, this raw material is called dimethyldimethoxysilane, and is inexpensive and has a hydrophobization rate. Since it can be hydrophobized quickly and reliably, a porous structure with high sound absorption efficiency can be produced at low cost without using supercritical drying, and a sound absorption dust removing filter with high sound absorption efficiency can be realized at low cost.

  In an eighth aspect of the invention, in particular, in any one of the first to seventh aspects of the invention, the catalyst or adsorbent is supported inside the porous structure by including a catalyst or adsorbent and having a deodorizing function. Alternatively, a sound absorbing dust filter having a deodorizing function can be realized by simply mixing the porous structure and the catalyst or adsorbent, or carrying the catalyst or adsorbent on the filter.

  The ninth aspect of the invention is particularly a vacuum cleaner provided with the sound absorbing dust removing filter according to any one of the first to eighth aspects of the invention, and by arranging the sound absorbing dust removing filter in the exhaust portion of the cleaner, the cleaner This prevents dust and other dust collected from flowing out to the outside along with the exhaust air, and realizes a quiet vacuum cleaner.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
1 and 2 show a sound absorbing dust removing filter according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the sound-absorbing dust removing filter 1 includes a case 5 having air permeability, a porous structure 2 having at least two continuous mesopores housed therein so as to vibrate, and a case 5. And a filter 3 for collecting suspended solids provided in a part of the filter.

  In the present embodiment, the case 5 includes a frame 5a and a honeycomb-shaped partition 5b provided inside the frame 5a, and houses the porous structure 2 having continuous mesopores in the honeycomb-shaped partition 5b. is doing. The partition 5b is not a necessary component. However, by providing such a partition 5b, there is an effect of preventing the porous structure 2 put in the frame 5a from gathering in the lower part due to gravity and forming a space in the upper part. Therefore, the shape is not limited to the honeycomb shape, and the size is not limited.

The filter 3 is made of a woven or non-woven fabric having air permeability. As shown in FIG. 1B, the upstream side or both sides of the case 5 in the ventilation direction 4 (upstream and downstream surfaces in the ventilation direction 4). It acts as a sealing material for sealing. At least the upstream filter 3 among the filters 3 uses the HEPA filter 3. Here, a HEPA filter is used as the filter 3, but traps suspended substances in the air using collection mechanisms such as "barrier", "inertia", "diffusion", "gravity sedimentation", and "static electricity". It is not particularly limited to the HEPA filter as long as the function can be given. However, since it is better that the dust removal performance is higher, for example, a non-woven fabric having a basis weight of 120 g / m ² , a thickness of 0.7 mm, a pressure loss of 85 Pa, and a dust collection efficiency of 99.97% is used. It is desirable.

  Next, the porous structure 2 and the sound absorption mechanism will be described. The sound absorption mechanism is as follows.

  When sound hits the surface of the porous structure 2, the air vibration is directly transmitted to the air in the pores of the porous structure 2. This causes viscous friction of the air in the pores, and part of the sound energy is converted into thermal energy, resulting in a sound absorbing action. Therefore, it is desirable that the pores are not closed cells but continuous. Further, when sound passes alternately through the solid portion and the gas portion of the porous structure 2, the sound energy is attenuated. Further, when the sound hits the porous structure 2, the porous structure 2. Begins to slightly vibrate, and when the vibrating porous structures 2 come into contact with each other, the vibration energy is changed to thermal energy, and the sound energy is attenuated to produce a sound absorbing action.

  As shown in FIG. 2, the porous structure 2 is composed of a skeleton in which primary particles 11 of about 1 to 50 nm are connected in a bead shape, and there is a space in which a large number of pores having a diameter of 12 between particles are formed. Therefore, it has a porous structure with continuous pores. Therefore, the length of the inter-particle distance 12, that is, the pore diameter depends on the primary particle diameter, and is generally divided into micropores (less than 2 nm), mesopores (2 to 50 nm), and macropores (50 nm or more) depending on the size. The

  In this embodiment, it is desirable to have many mesopores. This is due to the sound absorption mechanism. In the case of micropores, the pore diameter is small and the air does not move easily, so it is not suitable for viscous friction of air and conversion to thermal energy does not proceed so much. On the other hand, in the case of macropores, the pore diameter is large and small. Since the number of holes is reduced and the number of solid parts and gas parts through which sound passes is reduced and sound attenuation is reduced, the sound absorption effect is larger than micro holes, but the sound absorption effect is smaller than meso holes. . Further, the number of pores having a certain size increases as the amount of the space of the porous structure 2, that is, the porosity is larger, so that the porosity is preferably higher, and preferably about 70% to 95%. . However, if the porosity is too high, the porous structure 2 becomes very brittle and may break when aerated.

  The representative diameter of the porous structure 2 is desirably 1 mm or more. If it is smaller than this, if the ventilation is continued, the porous structure 2 is pushed away by the wind force, and a large gap is formed between the porous structures 2, so that the sound absorbing action is lowered. Moreover, when the filling rate of the porous structure 2 is increased in order to prevent this phenomenon, there is a problem that the pressure loss also increases. The representative diameter is not limited to one, and several representative diameters may be mixed. Further, the shape is not limited to a spherical shape.

  The material of the porous structure 2 is not particularly limited, but silica, alumina, titania and the like are preferable. Although a specific method for producing the porous structure 2 will be described later, it is desirable that the silica material is made of silica because the silica raw material is inexpensive and easy to obtain and easy to handle.

  For deodorization, the catalyst or adsorbent is supported inside the porous structure 2, or the porous structure 2 is simply mixed with the catalyst or adsorbent, or the catalyst or adsorbent is supported on the HEPA filter. By doing so, in addition to the dust removal and sound absorption functions, a sound absorption dust removal filter having a deodorizing function can be realized. Examples of the catalyst include transition metal oxide catalysts such as manganese and cobalt, noble metal catalysts such as platinum and palladium, and photocatalysts such as titanium oxide. However, when a photocatalyst is mounted, it is necessary to provide a separate light source, and the precious metal catalyst is preferably used in a state of being supported on a carrier such as alumina. Alternatively, it is desirable to support the filter 3 for use. As the adsorbent, hydrophobic zeolite, hydrophilic zeolite, sepiolite, silica gel, activated alumina, activated carbon and the like can be used. Since silica gel and activated carbon are easily available in granular form, they can be mixed with the porous structure 2. Can also be used.

  Such a sound-absorbing dust removing filter 1 can collect allergen substances such as dust, pollen and mites floating on the filter 3 with high efficiency, and the sound passes through a porous structure 2 having continuous mesopores. The sound energy is converted into heat energy, and the porous structure 2 receiving the sound energy vibrates and rubs against each other, and the conversion to heat energy produces a sound absorption effect, It can be used for air conditioners such as air cleaners and air conditioners.

(Embodiment 2)
Next, the porous structure of the sound absorbing dust removing filter according to Embodiment 2 of the present invention will be described.

  The manufacturing process of the porous structure 2 using supercritical drying for the drying process mainly includes the following three processes.

(1) Gelation step (formation of wet gel)
(2) Water removal step (removal of water in wet gel)
(3) Drying step (solvent removal in wet gel)
Hereinafter, each step will be described.

(1) Gelation step (formation of wet gel)
In this embodiment mode, a wet gel is prepared by a sol-gel method. Specifically, a metal alkoxide is used as a gel raw material, and a solvent such as water or alcohol is mixed with a catalyst for accelerating gelation, if necessary. Reaction) to form a wet gel. A wet gel can also be prepared by using water glass as a gel raw material and mixing with a catalyst for promoting gelation such as hydrochloric acid as necessary. Examples of the gel raw material used in the production of this embodiment include alkoxides such as silicon, aluminum, zirconium, and titanium, which are generally used in the sol-gel method. Among these, a compound containing silicon as a metal, that is, alkoxysilane is preferable from the viewpoint of easy availability and low cost.

  The wet gel is formed by adding alkoxysilane, alcohol as a solvent, acid or base as water for promoting gelation, and water to hydrolyze and polycondensate alkoxysilane. To do. Since water is necessary for hydrolyzing the alkoxysilane and the alkoxysilane and water are difficult to mix, the alkoxysilane and water can be uniformly mixed by adding alcohol. The wet gel produces silica particles having a three-dimensional network structure in which silicon atoms and oxygen atoms are alternately bonded, and the silica particles are polymerized to form primary particles 11 shown in FIG. A skeleton is formed, and the interparticle distance 12 of the primary particles 11 becomes gaps, that is, pores, and a solvent such as water enters.

  Next, the raw material alkoxysilane will be described. Examples of the alkoxysilane include tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane, trialkoxysilanes, alkoxysilanes such as dialkoxysilane, oligomers thereof, and the like, and mixtures thereof. In particular, tetramethoxysilane has a high silica content, and is inexpensive and easily available. Furthermore, tetramethoxysilane is suitable for the present embodiment because of its high reaction rate, that is, hydrolysis rate and condensation polymerization rate. . Furthermore, a tetramer or a 10-mer oligomer obtained by reacting alkoxysilane in advance may be used.

  As the gelation catalyst, a general organic acid, inorganic acid, organic base, or inorganic base is used. Examples of organic acids include acetic acid, citric acid, inorganic acids, sulfuric acid, hydrochloric acid, nitric acid, organic bases such as piperidine, and inorganic bases such as ammonia, formamide, and dimethylformamide. Among them, by using ammonia as ammonia water as a catalyst in the gelation step, there are advantages such as easy handling, the catalyst hardly remaining in the wet gel, and the advantage that the pore diameter can be easily controlled to 10 to 20 nm. There is also.

  After gelation, the formed wet gel is placed in a heated atmosphere as necessary, and the gel is aged by condensing unreacted silanol groups in the gel to increase the strength and suppress shrinkage during drying can do. It is desirable to hold for at least one day at a temperature of about 40-60 ° C.

(2) Water removal step (removal of water in wet gel)
The water removal step is a step of removing water in the wet gel and replacing it with a solvent having a lower critical temperature and lower critical pressure. When the wet gel is normally dried with hot air, it shrinks due to the surface tension when the solvent dries, crushes the pores, and the number of pores having a pore diameter of 1 nm or more is reduced. The force ΔP applied to the pores when the solvent evaporates is generally expressed by (Equation 1).

  Here, ΔP represents the capillary force, γ represents the surface tension of the solvent, θ represents the contact angle between the solvent and the skeleton, and d represents the pore diameter (pore diameter).

  Therefore, in order to reduce the capillary force, it is necessary to increase the contact angle θ or the surface tension γ. When the solvent in the wet gel is in a supercritical state, the surface tension γ is zero and no capillary force is generated. Accordingly, the porous structure 2 can be obtained because the pores do not shrink. However, since the critical temperature and critical pressure of water used for preparing the wet gel are large, there is a problem in safety and the cost is very high. Therefore, it is desired to use a solvent having a critical temperature and a critical pressure as low as possible during drying, particularly a solvent having a small critical pressure.

  As a water removal method, either a solvent replacement method or a heating distillation method is desirable. First, solvent replacement will be described.

  The general solvent replacement is performed by immersing the formed wet gel in a water-soluble solvent and replacing the solvent with the solvent in the gel. The solvent used at this time is not particularly limited as long as it is a water-soluble solvent and has a critical temperature and a critical pressure smaller than water (critical temperature: 374.2 ° C., critical pressure: 218.3 atm). For example, methanol (critical temperature: 240 ° C., critical pressure: 78.5 atm), ethanol (critical temperature: 243.1 ° C., critical pressure: 63 atm), propanol and tertiary-butanol, ethylene glycol, glycerol as water-soluble alcohols In addition to ketones and ethers such as acetone (critical temperature: 235.5 ° C., critical pressure: 46.6 atm), 1,4-dioxane, tetrahydrofuran, 1,3-dioxolane (critical temperature: 193.8 ° C., critical pressure: 36.2 atm), formamides such as dimethylformamide, lower carboxylic acids such as formic acid, acetic acid (critical temperature: 321.6 ° C., critical pressure: 57.1 atm) and propionic acid, Mixtures of these can be used. Among these, it is desirable to use alcohols such as methanol and ethanol which are inexpensive and easily available.

  Further, the replacement of the solvent is possible not only with the water-soluble solvent but also with a mixed solvent of the water-soluble solvent and another water-insoluble solvent. Specifically, it is a mixed solvent of n-hexane, decane, nonane, octane, heptane, toluene, xylene and the like and a water-soluble solvent. Particularly preferred for industrial use such as safety and availability are octane, toluene, xylene and the like.

  Next, heating distillation will be described. When water is removed by distillation by heating, it is generally possible to distill water preferentially by adding and heating a water-insoluble solvent having a boiling point higher than that of water. By using a water-insoluble solvent, the organic solvent and water are naturally separated after distillation by heating, so that the solvent can be easily reused. Moreover, even if the boiling point of the water-insoluble solvent is lower than the boiling point of water, if it is added excessively, it is possible to remove water, but by further increasing the boiling point of the solvent, the selectivity of water distillation Can be increased. For this reason, compared with the case where water is removed by solvent replacement, an effect of significantly reducing the amount of solvent used can be obtained. However, if the boiling point is too high, there is a disadvantage that the energy used increases.

  In addition, when water and the added solvent form an azeotrope, water and the solvent are distilled off at a constant rate, so that there is an effect that it is easy to control the removal of water. Furthermore, efficient water removal becomes possible by performing the heating and distillation under reduced pressure conditions as is done by drying an ordinary organic solvent. In particular, in the case where a gelling catalyst or the like is present, if the temperature is increased and dried by heating in a state containing water, bonds in the gel skeleton may be broken. In such a case, it is effective to prevent temperature rise by distilling water off under reduced pressure.

(3) Drying step (solvent removal in wet gel)
The drying method will be described. Drying is a step of removing the solvent that enters the wet gel instead of the water removed in the water removal step.

  A case where the solvent is ethanol will be described as an example. The internal water is removed, and the wet gel replaced with ethanol is placed in a pressure vessel, the pressure is raised above the critical pressure, and then the temperature is raised above the critical temperature to bring the ethanol into a supercritical state. Thereafter, by passing a substance compatible with ethanol in a supercritical state such as carbon dioxide, ethanol is extracted and replaced with carbon dioxide. After the pressure is reduced to atmospheric pressure, the temperature is lowered. Thereby, the porous structure 2 can be obtained.

  Further, after replacing a part of ethanol in the wet gel with carbon dioxide, the pressure is raised to a critical pressure of carbon dioxide or higher, the temperature is raised to a critical temperature or higher, and then carbon dioxide is circulated in a supercritical state. Thereafter, the flow is stopped, the pressure is lowered to atmospheric pressure, and then the temperature is lowered. Thereby, the porous structure 2 can be obtained more safely and at a lower cost than the supercritical drying of ethanol.

  The porous structure 2 produced in this way can collect allergen substances such as floating dust, pollen and mites with high efficiency, and sound passes through the porous structure 2 having continuous mesopores. The sound energy is converted into thermal energy, and the porous structure 2 that receives the sound energy vibrates and rubs with each other, and the conversion to the heat energy produces a sound absorption effect. A sound absorbing dust removing filter 1 having a dust removing action can be realized. And such a sound absorption dust-removing filter 1 can be used for air conditioners, such as a vacuum cleaner, an air cleaner, and an air conditioner.

(Embodiment 3)
Next, the porous structure of the sound absorbing dust removing filter according to Embodiment 3 of the present invention will be described.

  A specific manufacturing process of the porous structure 2 that does not use supercritical drying in the drying process mainly includes the following four processes.

(1) Gelation step (formation of wet gel)
(2) Hydrophobization step (hydrophobization of wet gel surface)
(3) Water removal step (removal of water in wet gel)
(4) Drying step (solvent removal in wet gel)
Hereinafter, each step will be described.

(1) Gelation step (formation of wet gel)
In this step, a wet gel is produced by the same method as in the second embodiment.

(2) Hydrophobization step (hydrophobization of wet gel surface)
In this step, the silanol group on the wet gel surface is replaced with a hydrophobic methyl group with, for example, trimethylchlorosilane, hexamethyldisilazane, dimethyldimethoxysilane, or the like. This has implications for a preliminary process before the drying process. As described above, the force ΔP applied to the pores during drying is expressed by (Equation 1). In this step, the contact angle θ is increased by introducing a hydrophobic group, and the capillary force ΔP generated during drying is decreased. With the goal. Note that the reduction of the surface tension γ will be described in the next water removal step. Hydrophobization is not limited to methyl groups, but ethyl groups, propyl groups, fluorine functional groups, and phenyl groups can provide almost the same effect. However, considering reactivity and cost, introduction of methyl groups Is desirable.

Furthermore, when trimethylchlorosilane, hexamethyldisilazane, or the like is used, gas such as hydrogen chloride or ammonia is generated, which may be used as a catalyst to break bonds between skeletons forming a wet gel. Moreover, when using these hydrophobizing agents, it is necessary to remove water beforehand, and one process will increase. Therefore, in this embodiment, hydrophobicity is performed using alkylalkoxysilane. That is, it has a hydrophobization step before the water removal step, and in the hydrophobization step, R and R ′ represent an alkyl group, x represents any integer of 1 to 3, and R _x (R ′ O) At least a part of the wet gel surface was hydrophobized using an alkylalkoxysilane represented by _4-xSi . Alkoxyalkoxysilanes used include monofunctional alkylalkoxysilanes such as methoxytrimethylsilane and ethoxytrimethylsilane, dimethoxydimethylsilane, dimethoxydiethylsilane, diethoxydimethylsilane, diethoxydiethylsilane and other bifunctional alkylalkoxysilanes, methyltrimethoxysilane And trifunctional alkylalkoxysilane compounds such as ethyltriethoxysilane.

  One of these or a mixture is dissolved in a solvent to be a hydrophobization treatment solution, and the wet gel and the solvent are allowed to react with each other. The reaction between the hydrophobizing agent and the silanol group requires water because the hydrophobizing agent needs to be hydrolyzed. Therefore, the solvent used as the hydrophobization treatment liquid is preferably a water-soluble solvent, and as the water-soluble solvent, water-soluble alcohols such as methanol, ethanol, propanol and tertiary-butanol, lower alcohols such as ethylene glycol and glycerol, and the like, Ketones and ethers such as acetone, 1,4-dioxane, tetrahydrofuran, 1,3-dioxolane, and mixtures thereof can also be used.

  In order to use alkylalkoxysilane as a hydrophobizing agent, water is required for hydrolysis, but the wet gel prepared in the gelation step contains water, so there is no need to add new water. It is also very desirable because it does not need to be dehydrated. In addition, by using ammonia water as a catalyst for gelation and water and methanol as solvents, alkylalkoxysilane can be directly added to the wet gel to make it hydrophobic.

  Furthermore, it discovered that bifunctional alkyl alkoxysilane was excellent in the hydrophobization efficiency among alkyl alkoxysilane. This is because the monofunctionality reduces the reactivity due to the steric hindrance of the three alkyl groups, and the trifunctionality makes it difficult for all three silanol groups resulting from hydrolysis to react with the silanol groups on the gel surface. This may be because it remains on the gel surface. Therefore, a bifunctional alkylalkoxysilane excellent in hydrophobization efficiency, particularly dimethyldimethoxysilane, has high reactivity and is highly desirable. That is, R and R ′ of the alkylalkoxysilane are both methyl groups and x = 2.

  Moreover, although the hydrophobization process is described after the gelation process, it can also be performed simultaneously with the gelation. However, at the same time as gelation, the hydrophobizing agent reacts with the gel raw material before polymerization to suppress the polymerization, or the amount of the required hydrophobizing agent increases due to the reaction with the gel raw material before polymerization. There is a case. Therefore, it is preferable that the hydrophobizing agent is allowed to act after the gelation is completed.

(3) Water removal step (removal of water in wet gel)
In this step, water and unreacted hydrophobizing agent in the wet gel are removed, and the amount is replaced with a solvent having a small surface tension γ.

  This process also has implications for the preliminary process of the drying process. According to (Equation 1), reducing the surface tension γ is also effective in reducing the capillary force. The surface tension of water is 0.072 N / m (25 ° C.), and other liquids such as general-purpose organic solvents such as toluene 0.027 N / m (30 ° C.) and ethanol 0.021 N / m (25 ° C.). ) And so on. It is therefore very important to reduce the proportion of water in the wet gel before drying and replace it with a solvent with a low surface tension instead.

  The water removal method is solvent replacement or heating distillation as in the second embodiment, but the solvent to be replaced is preferably a solvent having a small surface tension regardless of the critical temperature and the critical pressure.

  For the replacement of the solvent, the same solvent can be used in the same manner as in Embodiment 2. However, it is desirable to use alcohols such as methanol and ethanol which are inexpensive and easily available. Further, not only a water-soluble solvent but also a mixed solvent of a water-soluble solvent and another water-insoluble solvent is possible. The method for heating distillation is the same as in the second embodiment.

(4) Drying step (solvent removal in wet gel)
The drying method will be described. Drying is a step of removing the solvent introduced into the wet gel in place of the water removed in the water removal step, and the critical point of the solvent as the main component contained in the wet gel having at least a part of the surface hydrophobized. Dry under temperature and pressure conditions below.

  Since the capillary force is remarkably reduced by the hydrophobization step and the water removal step, even if hot air drying is performed in this state, the shrinkage to some extent can be suppressed, and the porous structure 2 can be obtained. The porous structure 2 having a larger porosity can be easily obtained by performing the above pressure at a pressure of at least atmospheric pressure and at least 2 atm. This is because if the drying is performed under pressure, the boiling point of the solvent retained in the pores increases. At this time, since the surface tension γ is lowered by the temperature rise, the capillary force is reduced and shrinkage is effectively suppressed, which is desirable. For example, when acetone is dried under pressure, if the boiling point is raised to about 45 ° C. and raised to about 100 ° C., the surface tension decreases to about 0.005 N / m and decreases to about 0.015 N / m. It can be said that drying under pressure is sufficiently effective in suppressing shrinkage. In addition, although you may dry by the supercritical drying described in Embodiment 2, the method mentioned above can produce the porous structure 2 safely at an overwhelmingly cheap cost.

  The porous structure 2 produced in this way can collect allergen substances such as floating dust, pollen and mites with high efficiency, and sound passes through the porous structure 2 having continuous mesopores. The sound energy is converted into thermal energy, and the porous structure 2 that receives the sound energy vibrates and rubs with each other, and the conversion to the heat energy produces a sound absorption effect. A sound absorbing dust removing filter 1 having a dust removing action can be realized. And such a sound absorption dust-removing filter 1 can be used for air conditioners, such as a vacuum cleaner, an air cleaner, and an air conditioner.

(Embodiment 4)
FIG. 3 shows a cleaner using a sound-absorbing dust filter in Embodiment 4 of the present invention.

  As shown in the figure, the vacuum cleaner is provided with a dust collection box 23 and an electric blower 24 inside the housing 21, a suction port 22 is provided in the housing 21, and the downstream side of the blowout port of the electric blower 24 is implemented. A sound absorbing dust removing filter 25 having the same configuration as that of the sound absorbing dust removing filter 1 in the first to third embodiments is installed.

The specific structure of the sound-absorbing dust removing filter 25 is made of ABS, and a breathable nonwoven fabric is attached to one side of a frame having an inner size of 144 mm × 87 mm and a thickness of 8 mm with a hot melt adhesive, and made of paper at 5 cells / inch ^2. Was installed in a frame, filled with 9.69 g of a porous structure 2 having a representative diameter in the range of 1 to 3.35 mm, and a HEPA filter was attached to the other surface with a hot melt adhesive. . In addition, the porous structure 2 gathered the thing which did not pass the sieve with a mesh opening of 3.35 mm among what was produced in Embodiment 3, and passed a sieve with a mesh opening of 1 mm.

  Next, the operation will be described.

  When the electric blower 24 is operated, air containing allergen substances such as dust, pollen, and ticks is drawn into the housing 21 through the suction port 22, and allergen substances such as dust, pollen, and ticks are collected in the dust collection box 23. Are separated. The air that has been purified to some extent passes through the electric blower 24 and the sound absorbing dust filter 25, and further purified air is exhausted to the outside of the housing 21. The operation sound of the electric blower 24 and the wind noise generated at this time can be attenuated by the sound absorption effect of the sound absorption dust removing filter 25. At the same time, allergen substances such as floating dust, pollen and mites can be collected with high efficiency.

  Thus, by arranging the sound absorbing dust removing filter 25 at the exhaust portion of the cleaner, dust or the like collected by the cleaner can be prevented from flowing out together with the exhaust gas, and a quiet cleaner can be realized.

  Next, based on FIG. 4, FIG. 5, the sound absorption coefficient measurement result of the various shape sample of the porous structure 2 in the sound absorption dust filter 1 is demonstrated.

  The sample prepared for measuring the sound absorption coefficient is the one in which the porous structure 2 is produced in the third embodiment, passes through a sieve having an opening of 3.35 mm, and does not pass through a sieve having an opening of 1 mm (hereinafter referred to as granular in this measurement) And a porous structure 2 produced in Embodiment 3 by crushing with a mixer to have a representative diameter of about 20 to 80 μm (hereinafter referred to as powder in this measurement). As a sound absorption coefficient measuring device, an amplifier set including a two-microphone impedance measurement tube BK4206 type manufactured by Bruel & Kjer and a normal incident sound absorption coefficient measurement software MS1021 type were used.

  The granularity was set in BK4206 so as to have a thickness of 11 mm, the back air layer was set to 0 mm, and the sound absorption coefficient for each frequency was measured. Further, the sound absorption coefficient was measured in the same manner with thicknesses of 15 mm and 20 mm. Similarly, the powder was set in BK4206 so as to have a thickness of 11 mm, and the sound absorption coefficient for each frequency was measured. Similarly, the sound absorption coefficient was measured with thicknesses of 5 mm and 15 mm.

  The granular results are shown in FIG. 4, and the powdery results are shown in FIG. The granular material exhibits a sound absorbing effect in a wide frequency band, and the frequency band in which the sound absorbing effect is exhibited moves to the low frequency side as the thickness increases. In the powder form, the frequency band in which the sound absorbing effect can be exhibited is narrower than that in the granular form, but the frequency band in which the sound absorbing effect is exhibited moves to the low frequency side by increasing the thickness. Although the mechanism by which the low frequency band where the sound absorption effect is exerted by the thickness moves is unknown, it has been found that the porous structure 2 has a sound absorption effect, and the sound absorption effect decreases as the size decreases. The decrease in the sound absorption effect due to the reduction in size is that the porous structure 2 particles having a lot of space are so light that each vibrated porous structure 2 particle moves around, and the particles collide with each other. This is considered to be because friction is generated only when the particles are in contact with each other, and the efficiency of conversion to thermal energy is deteriorated as compared with particles in which particles that are constantly vibrating are in contact.

  In particular, when the porous structure 2 is continuously ventilated as a sound-absorbing dust removing filter, the powder-like porous structure 2 particles are pushed away by the air flow to create a large space, and it is assumed that the sound absorption efficiency is further deteriorated. The

  In addition, the sound-absorbing dust removing filter in each of the first to fourth embodiments can be used as a substitute for a general sound-absorbing material such as glass wool, felt, and foamed polyurethane, and has excellent heat insulation performance. Can be used.

  As described above, the sound absorbing dust removing filter according to the present invention has a dust removing function for collecting allergen substances such as floating dust, pollen, and mites with high efficiency, and a sound absorbing function that can be expected to have a high sound absorbing effect. Since it has, it can implement | achieve a quiet vacuum cleaner by using for a vacuum cleaner. At the same time, it can be applied to air conditioners such as air purifiers and air conditioners.

(A) Schematic plan view of the sound-absorbing dust filter in Embodiment 1 of the present invention (b) Cross-sectional schematic diagram of the sound-absorbing dust filter Schematic diagram enlarging a part of the porous structure in the sound absorption dust filter Sectional drawing of the vacuum cleaner in Embodiment 4 of this invention The figure which shows the sound absorption rate measurement result of the sound absorption dust removal filter (granular form) in Embodiment 1 of this invention. The figure which shows the sound absorption coefficient measurement result of the same sound absorption dust removal filter (powder)

Explanation of symbols

1, 25 Sound absorbing dust filter 2 Porous structure 3 Filter 4 Ventilation direction 5 Case 11 Primary particle 12 Distance between particles

Claims (9)

A case having air permeability, a porous structure having continuous mesopores accommodated in at least two in a state where it can vibrate therein, and a filter for collecting suspended solids provided in a part of the case Sound absorption dust filter. The sound absorbing dust removing filter according to claim 1, wherein the filter is a HEPA filter. The sound absorbing dust removing filter according to claim 1, wherein the representative diameter of the porous structure is 1 mm or more. The porous structure includes a gelling step of forming a wet gel by mixing a solvent containing at least water and a gel raw material, a water removal step of removing water in the wet gel, and water removal in the water removal step. The sound-absorbing dust-removing filter according to any one of claims 1 to 3, wherein the sound-absorbing dust-removing filter is produced from a drying step of obtaining a porous structure by removing a solvent remaining in the wet gel. The sound absorbing dust filter according to claim 4, wherein in the gelation step, the gel raw material is an alkoxysilane monomer or oligomer, and at least the solvent contains water, alcohol, and an alkali catalyst that promotes gelation. A hydrophobization step before the water removal step, wherein R and R ′ represent an alkyl group, x represents an integer of 1 to 3, and R _x (R′O) Hydroxylalkoxysilane represented by _4-x Si is used to hydrophobize at least a part of the wet gel surface, and the drying step becomes a main component contained in the wet gel in which at least a part of the surface is hydrophobized. The sound-absorbing dust-removing filter according to claim 4, wherein the sound-absorbing dust-removing filter is a drying step in which drying is performed at a temperature lower than the critical point of the solvent and a pressure condition. The sound absorbing dust filter according to claim 6, wherein R and R 'are both methyl groups and x = 2. The sound absorbing dust removing filter according to any one of claims 1 to 7, comprising a catalyst or an adsorbent and having a deodorizing function. The vacuum cleaner provided with the sound-absorbing dust removal filter of any one of Claims 1-8.