JP4907582B2 - Air filter media - Google Patents

Description

  The present invention is a filter medium suitable for removing coarse dust, and in particular, a filter medium used to protect equipment from oily smoke and dust in a ventilation fan, a range hood, an air intake of an air conditioner, etc. used in a kitchen or kitchen. The present invention relates to a filter medium suitable for use as an air filter.

  In ventilation fans and range hoods used in kitchens and kitchens, or air intakes of air conditioners, filter media with flame retardancy are installed to protect these devices from oil smoke and dust in the air. Such a filter medium is called by a name such as a ventilation fan filter or a range hood filter depending on the equipment used. Such filter materials for equipment have the function of preventing oily smoke and dust in the air from entering the equipment and adhering to the rotor blades and electronic parts, causing trouble. If it is formed into a dense fiber structure with a small distance and the removal efficiency of oily smoke and dust is excessively increased, the pressure loss before and after the filter medium increases, and the problem arises that the air volume required by the device is rapidly reduced. For this reason, a filter material having a relatively coarse fiber structure is used as a filter medium for such devices. Further, in terms of maintenance, it is required that the filter can be used for as long as possible. For this reason, a filter material having a relatively large thickness is required so as to hold as much oil smoke and dust as possible.

  As such a filter medium for equipment, for example, a range hood filter disclosed in Patent Document 1 is known. This publication discloses a flame retardant range hood filter characterized in that a flame retardant containing guanidine phosphate as a main component is attached to a glass fiber filter material. It is disclosed that it is reinforced by cloth or non-woven fabric. However, since the fiber of the filter material is glass fiber, the filter material is not flexible, and there is a problem that the glass fiber breaks and the broken pieces of glass fiber scatter and pierce the hand or body, so handle with care. It was necessary. In addition, environmentally friendly materials have been demanded from recent social situations, and glass fibers cannot be incinerated and cannot be decomposed by disposal. Therefore, biodegradable materials have been sought as alternatives to glass fibers.

  As a filter medium using such a biodegradable material, for example, the filter medium of Patent Document 2 is known. This publication discloses a filter material in which a fiber web mainly composed of cellulose fibers is bonded with a flame retardant thermoplastic resin to which a metal hydroxide is added. Since this filter material uses a fiber web mainly composed of cellulose fibers, the constituent fibers have a biodegradable function. However, the flame retardant thermoplastic resin used is a resin made from petroleum such as vinyl chloride resin, vinylidene chloride resin, polyester resin, and acrylic resin, and has no biodegradation function. Resin. In this way, when a filter material is formed by bonding constituent fibers mainly composed of biodegradable fibers with a resin, if this resin is not biodegradable or is a resin made from petroleum, There was a problem that only a filter material with a limited degree of biodegradability could be obtained.

  In addition, as a filter medium using a biodegradable material, a filter base material in which biodegradable fibers are bonded with heat-fusible fibers as in Patent Document 3 is also known. However, when the constituent fibers are bonded with heat-fusible fibers, there is a problem that the thickness of the filter medium does not increase, and there is a problem that durability is inferior.

Further, as a filter medium in which biodegradable fibers are bonded with a biodegradable resin, for example, a filter made of a biodegradable flame retardant nonwoven fabric of Patent Document 4 is known. This publication discloses a filter that is flame-retardant treated by bonding between biodegradable fibers or non-woven fabric biodegradable fibers using a polylactic acid emulsion containing a non-halogen phosphate compound. However, when polylactic acid is used as a resin that binds the constituent fibers, the biodegradation function starts to work when the filter is stored, and strength deterioration occurs when the filter is used. Moreover, since polylactic acid resin was expensive, there existed a problem that manufacturing cost became high.

JP-A-5-168830 JP-A-9-234316 JP 2003-126628 A JP 2006-63473 A

  The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and in a filter medium in which constituent fibers including biodegradable fibers are bonded by a resin, the resin is made of a material that does not place an environmental burden. Accordingly, an object of the present invention is to provide an air filter medium that is excellent in bulkiness and durability and can be sufficiently considered in the environment.

Means for solving the above problem is that, in the invention according to claim 1, the constituent fiber including polylactic acid-based fiber formed from polylactic acid resin as biodegradable fiber is combined with natural rubber and acrylic polymer. A filter medium for an air filter, which is bonded by a natural rubber-based resin that is a polymerized resin, and 50% by mass or more of the constituent fibers are made of biodegradable fibers , and constitutes the filter medium for an air filter. Natural rubber resins are biodegradable because they are plant-based resins. In addition, even if the natural rubber-based resin is incinerated, it only releases carbon dioxide absorbed by plants, so that it does not increase the amount of carbon dioxide in the atmosphere. As a result, both the fibers and the resin constituting the air filter medium become a material that does not place a burden on the environment, and it is possible to provide an air filter medium that is excellent in bulkiness and durability and can be sufficiently considered for the environment. Further, since natural rubber-based resin is flexible, there is an advantage that there is little phenomenon that the resin falls as a powder.

The invention according to claim 1 is an air filter medium characterized in that the natural rubber-based resin is a resin obtained by copolymerizing an acrylic polymer with natural rubber, and has an advantage of particularly excellent durability. .

In the invention according to claim 2, wherein the copolymer is a filter medium for an air filter according to claim 1, characterized in that the graft copolymerization, Do sufficiently viable properties as natural rubber with particularly excellent durability There is an advantage that can be done.

In the invention which concerns on Claim 1 , 50 mass% or more of the said constituent fiber is a filter medium for air filters characterized by consisting of biodegradable fiber, and providing the filter medium for air filters fully considered for the environment. There is an advantage that you can.

In the invention which concerns on Claim 3 , it is a filter medium for air filters of Claim 1 or 2 characterized by including a flame retardant, and there exists an advantage that it is excellent in a flame retardance.

In the invention which concerns on Claim 4 , the said natural rubber-type resin contains the flame retardant, It is the filter medium for air filters in any one of Claims 1-3 , A constituent fiber contains a flame retardant. Bonded by the natural rubber-based resin contained. Such a filter material for air filter can be performed simultaneously with the step of binding the constituent fibers and the step of applying the flame retardant, and has an advantage of excellent production efficiency. Further, since natural rubber-based resin is flexible, there is an advantage that a resin containing a flame retardant is less likely to fall as a powder.

In the invention according to claim 5 , the flame retardant is a non-halogen flame retardant, and the non-halogen flame retardant is a hydrated metal compound, a hydrated silicate compound, red phosphorus, aluminum metaphosphate, magnesium phosphate, Condensed phosphate amide, ammonium phosphate, ammonium polyphosphate, ammonium carbonate, ammonium molybdate, zinc borate, antimony oxide, metal nitrate, metal complex, N-methyloldimethylphosphonopropionamide, polyphosphate carbamate, guanidine derivative phosphate A filter medium for an air filter according to claim 3 or 4 , wherein the flame retardant is a non-halogen-based flame retardant, wherein the flame retardant is selected from a cyclic phosphonate, a melamine phosphate, and a melamine cyanurate. Since it consists of a flame retardant, it has the advantage of being particularly environmentally friendly.

In the invention according to claim 6, the surface density of 30~300g / ^{m 2,} in filter medium for an air filter according to any one of claims 1 to 5 pressure loss is less than 30Pa at a wind speed 2m / sec In particular, there is an advantage that it is suitably used for a ventilation fan or a range hood.

  In a filter medium in which constituent fibers including biodegradable fibers are bonded by a resin, the resin is made of a material that does not place a burden on the environment, so that it is excellent in bulkiness and durability and can be sufficiently considered in the environment. A filter medium for an air filter can be provided.

  The present invention is a filter medium for an air filter in which constituent fibers including biodegradable fibers are bonded by a natural rubber resin.

  Examples of the biodegradable fibers include regenerated fibers such as rayon, natural fibers such as cotton and wool, and semisynthetic fibers such as acetate. Among these, it is preferable to contain rayon fibers in the constituent fibers, and by including rayon fibers, there is no advantage that the filter medium will not be pierced even if ignited, and that burning residue during combustion will be prevented from falling. .

  Examples of the biodegradable fiber include synthetic fibers such as polyvinyl alcohol fiber and polylactic acid fiber formed from polylactic acid resin. Here, the polylactic acid resin is a copolymer mainly composed of polylactic acid and / or polylactic acid. The lactic acid for producing polylactic acid may be only D-form, only L-form, or a mixture of D-form and L-form. Examples of the copolymer mainly composed of polylactic acid include lactic acid (D-form only, L-form alone, and a mixture of D-form and L-form), cyclic lactones such as ε-caprolactone, α-hydroxy, and the like. One or more monomers selected from butyric acid, α-hydroxyisobutyric acid, α-oxyacids such as α-hydroxyvaleric acid, glycols such as ethylene glycol and 1,4-butanediol, and dicarboxylic acids such as succinic acid and sebacic acid What copolymerized 2 or more types is mentioned. The proportion of copolymerization is preferably 10 parts by mass or less, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of lactic acid. The filter medium for an air filter of the present invention is an environmentally-friendly filter medium by including the biodegradable fiber in the constituent fibers.

  The biodegradable fiber is a composite fiber in which a polylactic acid resin A, which is a high molecular weight component, and a polylactic acid resin B, which is a low molecular weight component, are arranged side-by-side, and a cross section of the polylactic acid-based composite fiber It is preferable to include a polylactic acid-based composite fiber having a hollow portion having a hollowness of 10 to 40%. By including such a polylactic acid-based composite fiber, it can be a filter medium for an air filter that is excellent in bulkiness and resistance to compression and hardly causes settling, and is excellent in thickness recoverability.

  The polylactic acid-based composite fiber preferably has a hollowness in the cross section of 10 to 40%. Here, the hollowness is the ratio of the hollow part to the total cross-sectional area including the hollow part of the hollow composite fiber. By being hollow, the fiber is thicker than the mass of the fiber, and it can be a filter medium for an air filter that has excellent fiber rigidity and high bulkiness. Moreover, when compared with solid fibers having the same thickness, the raw material cost is reduced, and a light air filter medium can be obtained. In addition, when the hollowness in a cross section is less than 10%, the improvement effect of fiber rigidity or bulkiness may be lost. On the other hand, when the hollowness exceeds 40%, a hollow crack is likely to occur or the hollow portion is easily crushed, and the effect of improving the cushioning property of the air filter medium may be lost.

  The polylactic acid-based composite fiber is a fiber in which a polylactic acid resin A, which is a high molecular weight component, and a polylactic acid resin B, which is a low molecular weight component, are arranged side-by-side, and is generated due to a difference in molecular weight between the two resins. Spiral crimps appear due to the difference in shrinkage during stretching and heat treatment. By manifesting this spiral crimp, it can be a filter medium for an air filter which is excellent in bulkiness and resistance to compression and hardly causes settling, and has excellent thickness recoverability. The larger the difference in molecular weight between the polylactic acid resin A and the polylactic acid resin B, the more advantageous for crimp expression. However, if the difference in molecular weight is too large, the spinning stability is deteriorated. On the other hand, if the difference in molecular weight is too small, the expression of crimps decreases. Therefore, the difference between the number average molecular weight of the polylactic acid resin A and the number average molecular weight of the polylactic acid resin B is preferably 10,000 to 40,000, particularly preferably 15,000 to 35,000. Moreover, it is preferable that the number average molecular weights of the polylactic acid resin A are 60000-90000. The number average molecular weight of the polylactic acid resin B is preferably 50,000 to 80,000.

  The fineness of the polylactic acid-based composite fiber is preferably 10 to 50 dtex, and by having such a relatively high fineness, the air filter is excellent in fiber rigidity and, as a result, particularly excellent in resilience. It can be a filter medium. The fineness is more preferably 12 to 40 dtex, and still more preferably 12 to 30 dtex. If it is less than 10 dtex, the effect of improving fiber rigidity and bulkiness may not be obtained, or the effect of improving bulkiness and resilience may not be obtained. On the other hand, if it exceeds 50 dtex, the spinnability of the fiber is inferior, and the air filter medium may not be constructed.

  The polylactic acid-based composite fiber has the above-described form. For such a polylactic acid-based composite fiber, for example, Terramac HP8F manufactured by Unitika Ltd. can be used.

  The constituent fiber of the filter medium for an air filter of the present invention needs to contain the biodegradable fiber. The ratio including the biodegradable fiber is not particularly limited and can be appropriately determined according to the required level of the filter medium for the air filter, but preferably contains 50% by mass or more of the biodegradable fiber. Even if it is discarded after use, the biodegradation of the majority of the fibers will proceed and there is an advantage that it is environmentally friendly. Moreover, it is more preferable to contain 70 mass% or more, and it is still more preferable to contain 90 mass% or more. If it is less than 50% by mass, the entire filter material for air filter is inferior in biodegradability, and it may not be possible to obtain a filter material for air filter that is sufficiently environmentally friendly.

  The constituent fibers are preferably composed of polylactic acid-based fibers and rayon fibers. The blending ratio of the polylactic acid-based fibers to the rayon fibers is that the constituent fibers are 20 to 80% by mass of the polylactic acid-based fibers and the rayon fibers 80. The aspect which consists of -20 mass% is preferable, and the structure which consists of 30-70 mass% of said polylactic acid-type composite fibers and 70-30 mass% of rayon fibers is more preferable.

  The constituent fiber other than the biodegradable fiber is preferably an organic fiber from the viewpoint of disposal, and examples of the organic fiber include synthetic fibers such as polyamide fiber, polyolefin fiber, polyester fiber, and acrylic fiber. Mention may be made of fibers.

  Further, as other constituent fibers, it is also possible to include heat-adhesive fibers. Examples of such heat-adhesive fibers include fibers made of a single resin component having a lower melting point than other fibers and capable of thermally bonding other fibers, and other fibers having a lower melting point than other fibers. There is a composite fiber having a low melting point component that can be thermally bonded to the fiber surface. Such composite fibers include, for example, core-sheath type and side-by-side type composite fibers having a low melting point component on the fiber surface, and the material thereof is, for example, copolymer polyester / polyester, copolymer There are composite fibers made of a combination of fiber-forming polymers such as polypropylene / polypropylene, polypropylene / polyamide, polyethylene / polypropylene, polypropylene / polyester, and polyethylene / polyester.

  The constituent fibers of the air filter medium of the present invention preferably have an average fineness of 5 to 30 dtex, and the form of the fiber structure is not particularly limited. For example, the fiber structure has a multilayer structure of two or more layers. Even if it is a case, it is preferable if the average fineness of the whole constituent fiber is 5 to 30 dtex. In the present invention, by having such a relatively high fineness, the fiber has excellent rigidity, and as a result, it can be a filter medium for an air filter that is particularly excellent in bulkiness and resilience. The average fineness is more preferably 8 to 25 dtex, and further preferably 12 to 20 dtex. If it is less than 5 dtex, air filter media with excellent bulkiness and resilience may not be obtained, and pressure loss becomes too high, making it unsuitable as a filter for coarse dust filters or range hoods. There is a case. On the other hand, if it exceeds 30 dtex, the fiber structure becomes too coarse and dust collection may be insufficient.

  In addition, as a calculation method of the average fineness of a constituent fiber, the fineness of each fiber contained in a constituent fiber is set to a decitex, b decitex, c decitex, etc., and the content ratio of each fiber is a ′ mass%, b ′, respectively. Assuming that the mass%, c ′ mass%,... (A ′ / a) + (b ′ / b) + (c ′ / c)... = (100 / x) The average fineness x can be obtained from the equation.

  In the filter medium for an air filter of the present invention, the constituent fibers are bonded, but the form in which the constituent fibers are bonded is preferably a nonwoven fabric. Such a non-woven fabric can be a non-woven fabric conventionally used as a filter medium for air filters. For example, the non-woven fabric is formed by forming a fiber web by a dry method and then bonding and bonding with a natural rubber resin. It is possible. When such a dry process nonwoven fabric manufacturing method is used, it is easy to freely adjust the blending ratio of the constituent fibers, and there is an advantage that a uniform fiber web can be obtained. Specifically, the crimped fiber is formed into a fiber fleece by a carding machine, and a plurality of the fiber fleeces are laminated so as to cross each other to form a fiber web. If necessary, a fiber web is formed by laminating two or more layers of fiber fleece having different blending ratios of the constituent fibers. Next, this fiber web is coated and / or impregnated with a liquid natural rubber resin by spraying, printing, etc., and then dried by heating and thermally cured as necessary to bond the constituent fibers with the natural rubber resin. Thus, a filter medium for an air filter can be formed. Among these bonding methods, when the liquid natural rubber resin is applied by spraying and bonding, the fiber web can be bonded in a bulky state, so that a filter medium for air filter excellent in bulkiness can be formed. This is a preferred manufacturing method. It is also possible to pre-needle the fiber web before applying or impregnating the liquid natural rubber resin. This needle punching process is preferably a light needle punching process that does not reduce the thickness, and has an advantage that the bonding with a natural rubber-based resin can be reliably performed.

  Examples of the natural rubber-based resin include natural rubber and resins obtained by copolymerizing other resins with natural rubber. Among these, a resin obtained by copolymerizing an acrylic resin such as methyl methacrylate is particularly preferable, and a resin obtained by copolymerizing another resin with natural rubber has an advantage of particularly excellent durability. Further, this copolymerization is preferably graft polymerization, and has an advantage that it is particularly excellent in durability and the characteristics as a natural rubber can be fully utilized.

  The natural rubber resin is biodegradable because it is a plant-based resin. In addition, since natural rubber-based resin is a plant-based resin, it only releases carbon dioxide absorbed by plants even if incinerated, increasing the amount of carbon dioxide in the atmosphere. It doesn't matter. As a result, both the fibers and the resin constituting the air filter medium become a material that does not place a burden on the environment, and it is possible to provide an air filter medium that is excellent in bulkiness and durability and can be sufficiently considered for the environment. In addition, since the constituent fibers are bonded by natural rubber resin, the filter medium has excellent rubber elasticity and thickness recovery, and the natural rubber resin is flexible, so the resin becomes powder and fiber. There is an advantage that there is little phenomenon of falling off.

  In the present invention, the constituent fibers are bound by a natural rubber resin, but a form in which the constituent fibers are bound by a natural rubber composite resin in which a natural rubber resin and another resin are used in combination is also possible. In order to obtain such a form, for example, a liquid mixed resin in which a natural rubber-based resin and another resin are mixed can be applied to the constituent fibers. However, it is desirable that the mixing ratio of the natural rubber resin is high, preferably 50 to 99% by mass, more preferably 70 to 99%, more preferably 85 to 99% with respect to the natural rubber composite resin. More preferably.

  As the other resin, for example, a synthetic resin such as a thermoplastic resin or a thermosetting resin can be applied. For example, a polyacrylic resin, an acrylate resin, a urea resin, or a polyvinyl chloride resin. Polyvinylidene chloride resin, polyester resin, epoxy resin, polyamide resin, polyimide resin, polyolefin resin, polyether / ether ketone resin, polyphenylene sulfide resin, silicone resin, etc. can be applied it can. Among these resins, acrylic ester resins and urea resins that do not substantially contain a halogen element are preferable. In addition, a rubber-based resin such as a synthetic rubber-based resin can be used as the other resin. As the synthetic rubber resin, for example, SBR resin, NBR resin, and the like can be applied.

  As other resins, biodegradable resins such as poly (α-hydroxy acid) (for example, polyglycolic acid, poly-L-lactic acid, etc.), poly (β-hydroxyalkanoate) (for example, poly (α β-hydroxybutyric acid), β-hydroxybutyric acid-βhydroxyvaleric acid copolymer, etc.), poly (ω-hydroxyalkanoate) (eg, poly-β-propiolactone, poly-ε-caprolactone, etc.), polyalkoxy A range carboxylate (for example, polyethylene succinate, polybutylene succinate, butylene succinate-butylene adipate copolymer, etc.) can be applied, and at least one or more of these materials can be used as desired.

  In this invention, it is preferable that the mass ratio of the said constituent fiber and the said natural rubber-type resin is 50-10 mass% of natural rubber resin with respect to 50-90 mass% of constituent fibers, and 55-85 mass of constituent fibers. It is more preferable that it is 45-15 mass% with respect to%, and it is still more preferable that it is 40-20 mass% with respect to 60-80 mass% of constituent fibers. If the constituent fiber is less than 50% by mass, the thickness of the filter medium may not be sufficiently obtained, and there may be a problem that the amount of peeling of the natural rubber resin increases. Moreover, when a constituent fiber exceeds 90 mass%, it may be inferior to physical properties, such as a strength as a filter medium.

  The filter medium for an air filter of the present invention preferably contains a flame retardant, and as a form containing the flame retardant, for example, a flame retardant containing a flame retardant after the constituent fibers are bonded with a natural rubber resin There is a form obtained by applying the liquid by impregnation or spraying. Further, for example, a form obtained by binding the constituent fibers with a natural rubber resin containing a flame retardant is possible. In the present invention, the latter form is preferable, and there is an advantage that the production efficiency is excellent because a step of applying a flame retardant after the constituent fibers are bonded is not required. Further, since the natural rubber-based resin is flexible, there is an advantage that the resin containing the flame retardant becomes a powder and is less likely to fall off from the fiber.

  The flame retardant is not particularly limited, and any of an inorganic flame retardant and an organic flame retardant can be applied. Among these flame retardants, non-halogen flame retardants are preferable in consideration of the influence on the environment.

  Examples of inorganic non-halogen flame retardants that can be used include hydrated metal compounds, hydrated silicate compounds, phosphorus compounds, nitrogen compounds, boron compounds, antimony compounds, and the like. Hydrated metal compounds include aluminum hydroxide, magnesium hydroxide, calcium aluminate, etc., phosphorus compounds include red phosphorus, aluminum metaphosphate, magnesium phosphate, and condensed phosphate amides, and nitrogen compounds include There are ammonium phosphate, ammonium polyphosphate, ammonium carbonate, and ammonium molybdate, boron-based compounds include zinc borate, antimony-based compounds include antimony oxide, and other various metal nitrates and various metal complexes are applied. be able to. Of these, phosphorus flame retardants such as hardly soluble aluminum metaphosphate, magnesium phosphate and condensed phosphate amide, or hardly soluble aluminum hydroxide, magnesium hydroxide and the like are particularly preferable.

  In addition, as an organic non-halogen flame retardant, for example, a phosphorus flame retardant such as N-methyloldimethylphosphonopropionamide, polyphosphate carbamate, guanidine derivative phosphate, cyclic phosphonate, melamine phosphate, etc. Can do. In addition to the phosphorus-based flame retardant, a flame retardant such as melamine cyanurate can be applied.

  In the present invention, the mass ratio between the constituent fibers and the natural rubber resin containing the flame retardant (hereinafter sometimes referred to as a flame retardant-containing natural rubber resin) is difficult with respect to the constituent fibers of 25 to 75 mass%. It is preferable that it is 75-25 mass% of flame retardant containing natural rubber-type resins, It is more preferable that it is 68-32 mass% of flame retardant containing natural rubber-type resins with respect to 32-68 mass% of constituent fibers, and 40- The flame retardant-containing natural rubber resin is more preferably 60 to 40% by mass with respect to 60% by mass. When the constituent fiber is less than 25% by mass, there may be a case where the thickness as a filter medium cannot be sufficiently obtained, and there is a problem that the amount of the flame retardant-containing natural rubber resin becomes powder and drops off from the fiber. There is a case. Further, when the constituent fiber exceeds 75% by mass, physical properties such as strength as a filter medium may be inferior, and the amount of the flame retardant contained may be reduced, so that flame retardancy as a filter medium may be inferior.

  Further, the mass ratio of the natural rubber resin and the flame retardant is 65 to 10 mass% of the flame retardant with respect to 10 to 65 mass% of the natural rubber resin when the entire mass of the air filter medium is 100%. It is more preferable that the flame retardant is 15 to 15% by mass with respect to 15 to 50% by mass of the natural rubber resin, and 45 to 15% by mass of the flame retardant with respect to 15 to 45% by mass of the natural rubber resin. More preferably it is. When the natural rubber-based resin is less than 10% by mass, physical properties such as strength as a filter medium may be inferior. When the natural rubber-based resin exceeds 65% by mass, the amount of the flame retardant is relatively reduced and flame retardant May decrease. Moreover, a flame retardance may fall that a flame retardant is less than 10 mass%.

  The flame retardant-containing natural rubber-based resin can be uniformly applied and / or impregnated in the thickness direction with respect to the constituent fibers, but is applied so that the amount of the flame retardant increases on one side. It is also possible. By applying so that the amount of the flame retardant increases on one side, it is possible to further enhance the flame retardant effect by disposing the surface coated with a large amount of the flame retardant on the air inflow side. For example, the mass ratio of the flame retardant on the air outflow side and the mass ratio of the flame retardant on the air inflow side can be 1: 2 to 1:10, preferably about 1: 3 to 1: 7.

  In order to obtain the flame retardant-containing natural rubber resin, specifically, for example, as a flame retardant-containing resin liquid, a slurry in which a powdered non-halogen flame retardant is suspended in a liquid, and a liquid natural rubber resin A flame retardant-containing resin solution mixed with a resin is prepared. The slurry is generally obtained by mixing 20-80% by mass of a powdered non-halogen flame retardant and 80-20% by mass of water and dispersing the non-halogen flame retardant using a dispersion stabilizer. be able to. Alternatively, as the flame retardant-containing resin liquid, a flame retardant-containing resin liquid in which a liquid non-halogen flame retardant is dissolved or dispersed in another liquid and a liquid natural rubber resin is mixed is prepared. . The flame retardant-containing resin liquid may contain an antibacterial agent, an antifungal agent, a water repellent agent, or the like.

  In the present invention, when the biodegradable fiber in the constituent fiber, the natural rubber resin, and the non-halogen flame retardant are collectively referred to as an “environment-friendly material”, the mass of the biodegradable fiber in the constituent fiber The ratio of the mass of the environmentally friendly material formed by adding the mass of the natural rubber resin and the mass of the non-halogen flame retardant to the air filter medium is preferably 50% by mass or more, and 70% by mass. More preferably, it is more preferably 85% by mass or more. If the mass of the environmentally friendly material is less than 50% by mass, there may be a problem that the filter medium is not sufficiently environmentally friendly.

For the bulkiness of the filter medium for an air filter of the present invention, it is preferable that the apparent density of 0.005~0.04g / cm ^3, is preferably 0.008~0.035g / cm ^3, 0. More preferably, it is 01-0.03 g / cm < ³ >. Here, the apparent density is represented by a value obtained by dividing the mass per unit area by the thickness. The thickness is a value measured under a load of 0.5 g per 1 cm ² .

As an application of the filter medium for air filter of the present invention, it is suitable for coarse dust removal, a ventilation fan, a range hood, etc., and an area density suitable for such an application is preferably 30 to 300 g / m ² , is preferably 100 to 300 g / ^{m 2,} and still more preferably from 150 to 250 g / ^{m 2.} The thickness is preferably about 3 to 25 mm, more preferably 5 to 20 mm, and still more preferably 7 to 20 mm. The pressure loss at a wind speed of 2 m / sec is preferably 30 Pa or less.

Moreover, it is preferable that the filter medium for air filters of this invention is 1.0 g / m < ² > or less in the value of the amount of powder fall-off (g) defined by "the test method of powder fall-out" mentioned later, 0.8g / M ² or less is more preferable, and 0.6 g / m ² or less is still more preferable.

In addition, the air filter medium of the present invention preferably has a thickness compressibility (%) value of 90% or more, defined by the “thickness load resistance test method” described later, and is 91% or more. More preferably, it is more preferably 92% or more. Further, the bulk recovery rate (%) after releasing the load of 1 g / cm ² , that is, the value of the bulk recovery rate (%) defined in the “thickness load resistance test method” described later is 92% or more. It is preferably 93% or more, more preferably 96% or more.

  Moreover, when the flame retardance of the filter material for air filters of this invention is evaluated by A-1 method of JIS L1091 "Flammability test method of textile products", it is preferable that the evaluation value of flame retardancy is Category 3. In addition, when the flame retardant has a surface coated more than the other surface, the flame is applied to the coated surface.

  As described above, according to the present invention, in a filter medium in which constituent fibers including biodegradable fibers are bonded by a resin, the resin is made of a material that does not place a burden on the environment. It has become possible to provide a filter medium for an air filter that is excellent in the environment and sufficiently considers the environment.

  Examples of the present invention will be described below, but these are only suitable examples for facilitating understanding of the invention, and the present invention is not limited to the contents of these examples.

(Powder removal test method)
One 25 cm square test piece is collected from an arbitrary location on the evaluation sample. Moreover, a transparent bag made of polyethylene having a size of about 38 cm × about 26 cm for inserting the test piece is prepared, and the mass of the transparent bag is measured to obtain an initial mass (g). Next, after inserting the test piece into the transparent bag, the transparent bag with the test piece inserted is placed on a table with a smooth upper surface, and a metallic roll (diameter: about 10 cm, length: about 30 cm, mass) : 15 Kg) is reciprocated 10 times while rolling on a transparent bag. Next, the mass of the transparent bag is measured and set as the mass (g) after the test. Subsequently, the mass obtained by subtracting the initial mass from the mass after the test is obtained. The above test is repeated three times using different test pieces, and the average value of the three tests is divided by the area of the test piece to calculate the “amount of powder falling off (g / m ² )” per unit area.

(Thickness load test method)
Four test pieces of 25 cm square are collected from an arbitrary position with respect to the evaluation sample. Next, these test pieces were stacked and placed on a measuring table having a smooth upper surface, and a pressure plate having a square of 25 cm square and a mass of 312.5 g was placed on the four test pieces. The sample is placed so as to overlap with the test piece and pressed so that the load becomes 0.5 g / cm ² . Next, in the central part of each side of the test piece in this state, the thickness of the test piece in total of four places, one on each side, is measured and converted into an average value per one test piece. Record as Sasa.
Next, a pressure plate having a square of 25 cm square and a mass of 312.5 g is placed on the pressure plate so as to overlap with each other, and pressed so that the load becomes 1 g / cm ² . And this test piece is left to stand for 24 hours in this state. Thereafter, in the center of each side of the test piece with a load of 1 g / cm ² , the thickness of four test pieces in total, one on each side, is measured, and the average value per test piece is obtained. Convert to “thickness after loading”.
Next, after removing the pressure plate placed on the test piece and leaving it for 80 hours without pressure, the thickness at a load of 0.5 g / cm ² was adjusted in the same manner as the measurement of the initial thickness. Measured to be “recovered thickness”.
Next, the thickness compression rate (%) and the bulk recovery rate (%) are obtained from the following equations 1 and 2.
Thickness compression rate (%) = Thickness after loading (mm) × 100 / Initial thickness (mm) (Formula 1)
Bulk recovery rate (%) = recovered thickness (mm) × 100 / initial thickness (mm) (Formula 2)

(Preparation of resin solution 1)
A flame retardant made of a guanidine derivative phosphate is mixed with an emulsion made of company A made of a resin obtained by graft copolymerizing methyl methacrylate with natural rubber latex, and the mass ratio of the solid content is 70% resin and 30% flame retardant. Resin liquid A1 (liquid concentration: about 30%) adjusted to become a resin liquid A2 (liquid concentration: about 40%) adjusted so that the mass ratio of the solid content is 30% resin and 70% flame retardant Obtained.

(Preparation of resin solution 2)
A resin liquid (liquid) prepared by mixing a flame retardant made of a guanidine derivative phosphate with an emulsion made by Company B made of an acrylic resin, so that the mass ratio of the solid content is 70% resin and 30% flame retardant. Concentration: about 30%) A resin liquid B2 (liquid concentration: about 40%) was prepared so that the mass ratio of B1 and solids was 30% resin and 70% flame retardant.

Example 1
A solid type polylactic acid fiber (product name: Terramac PL01, fineness: 11 dtex, fiber length: 51 mm) manufactured by Unitika Ltd. was prepared. Next, 45% by mass of this polylactic acid fiber and 55% by mass of rayon fiber (fineness: 17 dtex, fiber length: 76 mm) are mixed, further formed into a fiber fleece by a card machine, and this fiber fleece is crossed. Thus, a plurality of sheets were laminated to form a fiber web having a surface density of 100 g / m ² .
Next, the resin liquid A1 (liquid concentration: about 30%) obtained in Preparation 1 of the resin liquid is spray-coated on one side of the fiber web so that the solid content adheres to a surface density of 30 g / m ^2. Dried. Next, the resin liquid A2 (liquid concentration: about 40%) obtained in Preparation 1 of the resin liquid is spray-coated on the opposite surface of the fiber web so that the solid content adheres to a surface density of 60 g / m ^2. Drying was followed by curing by heating to obtain a filter medium for an air filter having a surface density of 190 g / m ² .
A flame retardant-containing resin composed of a resin 39 g / m ² and a flame retardant 51 g / m ² is attached to the air filter filter medium, and this flame retardant-containing resin binds constituent fibers having an average fineness of 14 dtex. The ratio of environmentally friendly materials was 100%. Further, the thickness of the filter medium for air filter is 9.0 mm, the thickness after loading is 8.5 mm (thickness compression rate is 94%), and the recovery thickness is 8.7 mm (bulk recovery rate is 97 mm). %), The apparent density was 0.021 g / cm ³ , the pressure loss at a wind speed of 2 m / sec was 21 Mpa, and the amount of dust falling was 0.35 g / m ² . Further, when flame resistance is evaluated according to the A-1 method of JIS L1091 “Flame Flammability Test Method” by applying a flame from the surface on which a large amount of flame retardant is applied by application of the resin liquid A2, flame retardancy is obtained. The air filter material was excellent in bulkiness and resilience, and suitable as a filter material for a range hood, while having a flame retardancy and an excellent biodegradability function.

(Example 2)
In forming the fiber web of Example 1, a polylactic acid composite fiber (product name: Terramac HP8F, fineness: 17 dtex, fiber length: 64 mm) manufactured by Unitika Ltd. was prepared, and then 45 mass of this polylactic acid composite fiber. % And rayon fibers (fineness: 17 dtex, fiber length: 76 mm) are mixed to form a fiber fleece by a card machine, and a plurality of layers are laminated so that the fiber fleeces cross each other. A filter medium for an air filter having a surface density of 190 g / m ² was obtained in the same manner as in Example 1 except that a fiber web having a density of 100 g / m ² was formed. This polylactic acid-based composite fiber is a composite fiber in which a polylactic acid resin as a high molecular weight component and a polylactic acid resin as a low molecular weight component are arranged side-by-side, and has a hollowness of 22% in the cross section of the composite fiber. It had a hollow part.
A flame retardant-containing resin composed of a resin 39 g / m ² and a flame retardant 51 g / m ² is attached to the air filter filter medium, and this flame retardant-containing resin binds constituent fibers having an average fineness of 17 dtex. The ratio of environmentally friendly materials was 100%. Moreover, the thickness of this air filter medium is 11.9 mm, the thickness after load is 11.1 mm (thickness compressibility is 93%), and the recovery thickness is 11.6 mm (bulk recovery rate is 97). %), The apparent density was 0.016 g / cm ³ , the pressure loss at a wind speed of 2 m / sec was 20 Mpa, and the amount of dust fall was 0.21 g / m ² . Further, when flame resistance is evaluated according to the A-1 method of JIS L1091 “Flame Flammability Test Method” by applying a flame from the surface on which a large amount of flame retardant is applied by application of the resin liquid A2, flame retardancy is obtained. The air filter material was excellent in bulkiness and resilience, and suitable as a filter material for a range hood, while having a flame retardancy and an excellent biodegradability function.

Example 3
In the fiber web formation of Example 1, 55% by mass of polylactic acid-based composite fiber similar to Example 2 and 45% by mass of polyester fiber (fineness: 17 dtex, fiber length: 51 mm) were mixed, and further a card machine A surface density of 190 g / m was obtained in the same manner as in Example 1 except that a fiber web having a surface density of 100 g / m ² was formed by laminating a plurality of the fiber fleeces so as to intersect with each other. No. ² filter medium for air filter was obtained.
A flame retardant-containing resin composed of a resin 39 g / m ² and a flame retardant 51 g / m ² is attached to the air filter filter medium, and this flame retardant-containing resin binds constituent fibers having an average fineness of 17 dtex. The ratio of environmentally friendly materials was 76%. Further, the thickness of the filter medium for air filter is 12.0 mm, the thickness after load is 11.5 mm (thickness compressibility is 96%), and the recovery thickness is 11.8 mm (bulk recovery rate is 98). %), The apparent density was 0.016 g / cm ³ , and the pressure loss at a wind speed of 2 m / sec was 16 Mpa. Moreover, the amount of powder fall-off was 0.23 g / m ² . Further, when flame resistance is evaluated according to the A-1 method of JIS L1091 “Flame Flammability Test Method” by applying a flame from the surface on which a large amount of flame retardant is applied by application of the resin liquid A2, flame retardancy is obtained. The air filter material was excellent in bulkiness and resilience, and suitable as a filter material for a range hood, while having a flame retardancy and an excellent biodegradability function.

(Comparative Example 1)
In Example 1, on one side of the fiber web, the resin liquid B1 (liquid concentration: about 30%) obtained in Preparation 2 of the resin liquid was spray-coated so that the solid content adhesion was a surface density of 30 g / m ² . In addition, the resin liquid B2 (liquid concentration: about 40%) obtained in the resin liquid preparation 2 was spray-coated on the opposite surface of the fiber web so that the solid content was 60 g / m ^2. In the same manner as in Example 1, an air filter medium having an areal density of 190 g / m ² was obtained.
A flame retardant-containing resin composed of a resin 39 g / m ² and a flame retardant 51 g / m ² is attached to the air filter filter medium, and this flame retardant-containing resin binds constituent fibers having an average fineness of 14 dtex. The ratio of environmentally friendly materials was 79%. Moreover, the thickness of this air filter medium is 8.1 mm, the thickness after load is 7.0 mm (thickness compressibility is 86%), and the recovery thickness is 7.3 mm (bulk recovery rate is 90 mm). %), The apparent density was 0.023 g / cm ³ , the pressure loss at a wind speed of 2 m / sec was 23 Mpa, and the amount of dust fall was 1.35 g / m ² . When flame resistance is evaluated by the A-1 method of JIS L1091 “Flame Flammability Test Method” by applying a flame from the surface on which a large amount of flame retardant is applied by application of the resin liquid B2, flame retardancy is obtained. The evaluation value of this was Category 3, and this air filter medium had a flame retardant function, but the biodegradable function was insufficient compared to the air filter medium of Example 1, In addition, the amount of powder falling was large, and the bulkiness and resilience were inferior, making it unsuitable as a filter medium for removing coarse dust and for range hoods.

(Comparative Example 2)
In Example 2, the one side of the fiber web was spray-coated with the resin liquid B1 (liquid concentration: about 30%) obtained in Preparation 2 of the resin liquid so that the solid content adhesion was a surface density of 30 g / m ² . In addition, the resin liquid B2 (liquid concentration: about 40%) obtained in the resin liquid preparation 2 was spray-coated on the opposite surface of the fiber web so that the solid content was 60 g / m ^2. In the same manner as in Example 1, an air filter medium having an areal density of 190 g / m ² was obtained.
A flame retardant-containing resin composed of a resin 39 g / m ² and a flame retardant 51 g / m ² is attached to the air filter filter medium, and this flame retardant-containing resin binds constituent fibers having an average fineness of 17 dtex. The ratio of environmentally friendly materials was 79%. Moreover, the thickness of this air filter medium is 10.6 mm, the thickness after loading is 9.9 mm (thickness compressibility is 93%), and the recovery thickness is 10.1 mm (bulk recovery ratio is 95). %), The apparent density was 0.018 g / cm ³ , the pressure loss at a wind speed of 2 m / sec was 17 MPa, and the amount of dust fall was 1.13 g / m ² . When flame resistance is evaluated by the A-1 method of JIS L1091 “Flame Flammability Test Method” by applying a flame from the surface on which a large amount of flame retardant is applied by application of the resin liquid B2, flame retardancy is obtained. The air filter material had a flame-retarding function and was excellent in bulkiness and resilience, but compared with the air filter material of Example 2. In addition, the biodegradable function is insufficient and the amount of powder falling is large, which makes it unsuitable as a filter medium for removing coarse dust or for range hoods.

(Comparative Example 3)
In the fiber web formation of Example 1, 70% by mass of polyester fiber (fineness: 17 dtex, fiber length: 51 mm) and 30% by mass of rayon fiber (fineness: 17 dtex, fiber length: 76 mm) were further mixed. It was formed into a fiber fleece by a card machine, and a plurality of sheets were laminated so that the fiber fleeces intersected to form a fiber web having a surface density of 100 g / m ^{2. On} one side of the fiber web, resin liquid preparation 2 The obtained resin liquid B1 (liquid concentration: about 30%) was spray-coated so that the solid content was 30 g / m ² and the resin obtained in the resin liquid preparation 2 on the opposite surface of the fiber web Liquid B2 (liquid concentration: about 40%) was spray-coated so that the adhesion of the solid content was 60 g / m ² , except that the surface density was 190 g / m ² . A filter medium for afilter was obtained.
A flame retardant-containing resin composed of a resin 39 g / m ² and a flame retardant 51 g / m ² is attached to the air filter filter medium, and this flame retardant-containing resin binds constituent fibers having an average fineness of 17 dtex. The ratio of environmentally friendly materials was 43%. Further, the thickness of the filter material for air filter is 11.2 mm, the thickness after loading is 10.7 mm (thickness compressibility is 96%), and the recovery thickness is 11.0 mm (bulk recovery rate is 98). %), The apparent density was (0.017) g / cm ³ , the pressure loss at a wind speed of 2 m / sec was 18 Mpa, and the amount of dust falling was 1.23 g / m ² . When flame resistance is evaluated by the A-1 method of JIS L1091 “Flame Flammability Test Method” by applying a flame from the surface on which a large amount of flame retardant is applied by application of the resin liquid B2, flame retardancy is obtained. The air filter material has a flame-retardant function and is excellent in bulkiness and resilience, but compared with the air filter media of Examples 1 to 3. Therefore, the biodegradable function is insufficient, and the amount of powder falling is large, which makes it unsuitable as a filter medium for removing coarse dust and for range hoods.

Claims (6)

A constituent fiber including a polylactic acid fiber formed from a polylactic acid resin as a biodegradable fiber is bound by a natural rubber resin, which is a resin obtained by copolymerizing an acrylic polymer with natural rubber , A filter medium for an air filter, wherein 50% by mass or more is made of a biodegradable fiber . The air filter medium according to claim 1 , wherein the copolymerization is graft copolymerization. The filter medium for an air filter according to claim 1 or 2 , comprising a flame retardant. The air filter medium according to any one of claims 1 to 3 , wherein the natural rubber-based resin contains a flame retardant. The flame retardant is a non-halogen flame retardant, and the non-halogen flame retardant is a hydrated metal compound, a hydrated silicate compound, red phosphorus, aluminum metaphosphate, magnesium phosphate, condensed phosphate amide, or ammonium phosphate. , Ammonium polyphosphate, ammonium carbonate, ammonium molybdate, zinc borate, antimony oxide, metal nitrate, metal complex, N-methyloldimethylphosphonopropionamide, polyphosphate carbamate, guanidine derivative phosphate, cyclic phosphonate, phosphoric acid The air filter medium according to claim 3 or 4 , wherein the filter medium is a flame retardant selected from melamine and melamine cyanurate . Surface density of 30~300g / ^{m 2,} the filter medium for an air filter according to any one of claims 1 to 5 pressure loss is less than 30Pa at a wind speed 2m / sec.