JP2020007698A - Inorganic fiber paper - Google Patents

Abstract

To provide an inorganic fiber paper with its density controlled in a favored range while improving impregnation property before firing.SOLUTION: The inorganic fiber paper is a sheeted substrate obtained by wet type sheet making using a living matter solubility ceramic fiber, a glass fiber with its blending ratio in the fiber content being 0 weight% or over and 70 weight% or under, an organic fiber with an average fiber diameter of 17 μm or over and 25 μm or under, at least one kind or over of a cationic inorganic binder selected from aluminium sulfate, polyaluminum chloride, cationic colloidal silica, and alumina sol, and sepiolite with its blending ratio toward the fiber content being 20 weight% or over and 60 weight% or under.SELECTED DRAWING: None

Description

  The present invention relates to an inorganic fiber paper using a biosoluble ceramic fiber.

  Ceramic fiber has excellent properties as an industrial material, and its use in all industries such as steel, petroleum, chemical, electricity, automobiles, building materials, aerospace, etc. has become established. It is used in various applications such as filtration materials, heat-resistant insulation materials, heat-resistant seal materials, heat-resistant packing materials, heat-resistant cushioning materials, and heat-resistant cushion materials.

  As the ceramic fiber, an amorphous refractory ceramic fiber (hereinafter referred to as RCF) mainly used at a normal temperature of 1,250 ° C. or lower, and an alumina crystalline material used at a temperature higher than 1,250 ° C. Ceramic fibers are known. These RCFs and crystalline ceramic fibers have greatly different production methods, performances, and prices, and are properly used depending on their characteristics. However, there are concerns about the effects of ceramic fibers on the human body. In particular, the RCF has issued a "decree that partially revises the Ordinance for Enforcement of the Industrial Safety and Health Law" (2015 Cabinet Order No. 294) and "Occupational Safety and Health Regulations". Regulations such as the amendment of some of the specified chemical substances are specified in the Ministry of Health, Labor and Welfare Order No. 141 (2015). Therefore, instead of RCF, an inorganic fiber paper using a biosoluble ceramic fiber having little effect on the human body has been proposed (for example, see Patent Document 1).

JP 2003-105662 A

  However, biosoluble ceramic fibers contain calcium oxide (CaO), magnesium oxide (MgO), and the like as modifying oxides, and have a significant difference in chemical composition from RCF composed of silica (SiO2) and alumina (Al2O3). There is. Further, biosoluble ceramic fibers generally have a difference in that the average fiber diameter is larger than that of RCF and the dispersion thereof is large. Due to these differences, the density of the inorganic fiber paper using the biosoluble ceramic fiber tends to be lower than that of the inorganic fiber paper using the RCF, and the workability such as cutting and punching may be poor. On the other hand, if the density is unnecessarily increased, the impregnating property deteriorates, and it becomes difficult to impregnate the impregnating liquid composed of the dispersion of the particles of the functional agent such as the catalyst or the adsorbent and the dispersion of the inorganic binder, and There is a risk that it will be difficult to sufficiently support it.

  Here, the inorganic fiber paper loses its organic components when fired, so that the strength is reduced after firing and the handling properties are deteriorated. Furthermore, the impregnating liquid is easier to impregnate in a sheet-like state before firing than after firing after forming such as bending. In these respects, it is more advantageous to impregnate the inorganic fiber paper before firing with the impregnating liquid than to impregnate the inorganic fiber paper after firing with the impregnating liquid. It is difficult to ensure the impregnation before firing, and the fact is that the impregnation before firing is not considered.

  The present invention focuses on impregnating an impregnating liquid before firing in inorganic fiber paper using biosoluble ceramic fibers having little effect on the human body, and adjusting the density to a suitable range while impregnating the impregnating property before firing. It is an object of the present invention to provide an inorganic fiber paper having improved properties.

The inorganic fiber paper of the present invention to solve the above object, a biosoluble ceramic fiber,
A glass fiber having a blending ratio of 0% by weight or more and 70% by weight or less in a fiber content,
Organic fibers having an average fiber diameter of 17 μm or more and 25 μm or less,
Aluminum sulfate, polyaluminum chloride, cationic colloidal silica, at least one or more cationic inorganic binders selected from alumina sol,
It is characterized in that it is a sheet-form base material obtained by wet papermaking using sepiolite having a blending ratio of 20% by weight or more and 60% by weight or less with respect to the fiber content.

Further, in the inorganic fiber paper of the present invention, the liquid retention amount before firing is preferably 100 g / m ² or more.

  ADVANTAGE OF THE INVENTION According to this invention, the inorganic fiber paper which improved the impregnation property before baking, adjusting a density in a suitable range can be provided.

  Hereinafter, the inorganic fiber paper of the present invention will be described in detail. The inorganic fiber paper of the present invention is a sheet-form base material obtained by wet papermaking using a biosoluble ceramic fiber, a glass fiber, an organic fiber, a cationic inorganic binder as an inorganic binder and sepiolite. Further, the inorganic fiber paper of the present invention can be suitably used as a heat-resistant catalyst supporting material, a heat-insulating material, a heat-resistant filter material, a heat-resistant insulating material, a heat-resistant seal material, a heat-resistant packing material, a heat-resistant cushioning material, a heat-resistant cushion material, and the like.

  The biosoluble ceramic fibers used in the present invention are selected from fibers classified into Category 0 (exempt substances) in the regulation of the EU Directive 97/69 / EC. For that purpose, safety is proved in one of the following four types of animal tests by NotaQ “criterion for dissolving fiber in vivo”, or length-weighted geometry by NotaR “criterion for non-respirable fiber”. It is necessary that the value of the fiber obtained by subtracting twice the standard deviation from the average fiber diameter exceeds 6 μm.

(1) In a living body retention test by short-term inhalation, a fiber longer than 20 μm has a load half-life of less than 10 days;
(2) In a living body retention test by short-term endotracheal injection, a fiber longer than 20 μm has a load half-life of less than 40 days;
(3) no evidence of excessive carcinogenicity by intraperitoneal administration test;
(4) No relevant pathogenic or neoplastic changes in long-term inhalation studies.

  As long as the biosoluble ceramic fiber has been confirmed to have the above safety, its production method, chemical composition, average fiber diameter or average fiber length is not particularly limited, and for example, biosoluble rock wool can be used. .

  In addition, many of the biosoluble ceramic fibers include a non-fibrous material (a granular material close to a sphere, usually called "shot") at the fiber tip due to a manufacturing problem. If the content of the shot is high, the physical strength is reduced, and problems such as pinholes and powder dropping are liable to occur during wet papermaking, and stable production is difficult. Therefore, in the inorganic fiber paper of the present invention, the shot content of 45 μm or more contained in the biosoluble ceramic fibers is preferably 4% or more and 20% or less, more preferably 5% or more and 18% or less. % Or more and 15% or less. In order to reduce the content of shots of 45 μm or more to less than 4%, it is necessary to repeatedly perform the de-shot processing, and the effect of the repeated processing may shorten the fiber length and deteriorate the physical strength, which is not preferable in terms of cost. . On the other hand, if the content of 45 μm or more exceeds 20%, non-fibrous materials that do not contribute to the strength increase, and thus the physical strength may be poor. The method of removing the shot is not particularly limited, but is achieved by a method of cutting the shot and the fiber by applying a high shear force, or a method of separating the shot from the fiber using a removing device such as a screen or a cyclone.

  In the inorganic fiber paper of the present invention, the blending ratio of the biosoluble ceramic fiber in the fiber content is preferably from 10% by weight to 95% by weight, more preferably from 20% by weight to 80% by weight, It is still more preferably from 30% by weight to 80% by weight, and still more preferably from 40% by weight to 80% by weight. If the compounding ratio is less than 10% by weight, the physical strength of the inorganic fiber paper may be poor, and fine pinholes may be generated in the final product due to the decrease in the density of the inorganic fiber paper. On the other hand, if the compounding ratio exceeds 95% by weight, the physical strength may decrease.

  In the inorganic fiber paper of the present invention, the compounding ratio of glass fiber in the fiber content is 0% by weight or more and 70% by weight or less. If the mixing ratio of the glass fibers exceeds 70% by weight, the formation of the inorganic fiber paper may be poor, causing variations in the quality or pinholes due to fine holes. When it is desired to improve the heat resistance, the mixing ratio of the glass fibers may be 0% by weight (an embodiment in which no glass fibers are mixed).

  Further, the glass fiber in the present invention preferably has a fiber length of 1 mm to 30 mm, more preferably 2 mm to 15 mm, still more preferably 3 mm to 10 mm. If the fiber length is less than 1 mm, the physical strength may be insufficient. On the other hand, if the fiber length exceeds 30 mm, the formation of the inorganic fiber paper becomes poor, and the quality may vary. Further, the average fiber diameter of the glass fibers in the present invention is preferably 5 μm or more and 15 μm or less, more preferably 5 μm or more and 11 μm or less, and still more preferably 5 μm or more and 9 μm or less. If the average fiber diameter is less than 5 μm, the fibers may be too thin to deteriorate the liquid retention. On the other hand, if the average fiber diameter exceeds 15 μm, it becomes too thick, the gap between the fibers becomes large, the physical strength is inferior, the skin is irritating, and the workability is hindered. is there.

  As the organic fiber in the present invention, a pulp-like material made of cellulose fiber and synthetic resin short fiber can be used, and each can be used alone or in combination of both. However, when the organic fibers are composed only of the cellulose fibers, the physical strength can be improved and the cost can be suppressed.

  Further, the organic fiber according to the present invention has an average fiber diameter of 17 μm or more and 25 μm or less. If the average fiber diameter of the organic fibers is less than 17 μm, the density of the inorganic fiber paper becomes too high, and the impregnation before firing may be deteriorated. On the other hand, when the average fiber diameter of the organic fibers exceeds 25 μm, the density of the inorganic fiber paper becomes too low, and there is a possibility that the workability such as cutting and punching and the physical strength may be reduced.

  The pulp-like material composed of cellulose fibers used in the present invention includes softwood bleached kraft pulp (hereinafter, referred to as NBKP), hardwood bleached kraft pulp (hereinafter, referred to as LBKP), softwood sulfite pulp, hardwood sulfite pulp, Esparto or any other type of pulp is not limited at all, but NBKP is more preferable from the viewpoint of the physical strength of the inorganic fiber paper during wet papermaking. The freeness (Canadian standard freeness) is not particularly limited, but is preferably in the range of 200 ml CSF or more and 700 ml CSF or less, more preferably in the range of 300 ml CSF or more and 700 ml CSF or less, and more preferably 400 ml CSF or more and 700 ml CSF or less. Is more preferably within the range. When the freeness is less than 200 ml CSF, the clogging occurs at the stage of forming the inorganic fiber paper by the wet papermaking method, the drainage becomes poor, and a uniform formation may not be obtained. May be too high. On the other hand, if it is higher than 700 ml CSF, the fineness of the fiber is poor, the entanglement is poor, the physical strength is poor, and the inorganic fiber paper may not be successfully formed.

  Examples of the resin constituting the synthetic resin short fiber used in the present invention include polyvinyl alcohol resin (hereinafter, referred to as PVA), polyester resin, polyolefin resin, acrylic resin, polyvinyl acetate resin, ethylene-acetic acid. Vinyl copolymer resin, polyamide resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl ether resin, polyvinyl ketone resin, polyether resin, diene resin, polyurethane resin, phenol resin, melamine Resin, furan resin, urea resin, aniline resin, unsaturated polyester resin, alkyd resin, fluorine resin, silicone resin, polyamideimide resin, polyphenylene sulfide resin, polyimide resin, derivatives of these resins, etc. Is mentioned.

  As the inorganic binder, a cationic inorganic binder and sepiolite are essential components. As the cationic inorganic binder, at least one selected from aluminum sulfate, polyaluminum chloride, cationic colloidal silica, and alumina sol can be used. Examples of the stabilizer for alumina sol include hydrochloric acid, acetic acid, and nitric acid, and any of them may be used. The shape of the alumina sol may be a feather-like or plate-like structure, and any of them may be used. The compounding ratio of the cationic inorganic binder in the present invention is preferably 0.1% by weight or more and 5% by weight or less, more preferably 0.1% by weight or more and 3% by weight or less based on the total weight of the fibers. More preferably, the amount is from 1% by weight to 1% by weight. When the compounding ratio of the cationic inorganic binder is less than 0.1% by weight, the wet tensile strength may be poor. On the other hand, when the compounding ratio of the cationic inorganic binder exceeds 5% by weight, cohesion becomes too strong, and formation failure may be caused or liquid absorbing property may be deteriorated.

  Sepiolite in the present invention is a clay mineral having a large number of active hydroxyl groups on the surface thereof made of hydrous magnesium silicate, and is not limited in its shape at all.Other than fibrous, bulk, mud, powder, Can also be used. In addition, talc, calcite, dolomite, magnesite, basic magnesium carbonate, a silicate component and the like as host rocks and intercalation stones may be contained. There are no particular restrictions on countries of origin such as Spanish, Turkish and Chinese.

  The mixing ratio of sepiolite used in the present invention is preferably 20% by weight or more and 60% by weight or less with respect to the fibers (biosoluble ceramic fibers, glass fibers, and organic fibers) constituting the inorganic fiber paper. The content is more preferably not less than 55% by weight and more preferably not less than 55% by weight. When the compounding ratio is less than 20% by weight, the physical strength may be insufficient, and when the compounding ratio is more than 60% by weight, powder falling off the inorganic fiber paper may be deteriorated.

  Further, other natural mineral fibers such as wollastonite and attapulgite may be blended together with sepiolite, which is one of the natural mineral fibers. In addition, for example, a clay mineral such as palygorskite, which is usually called mountain cork, mountain leather, mountain wood, or the like, colloidal silica, lithium silicate, or the like may be appropriately selected and used.

  The basis weight of the inorganic fiber paper can be arbitrarily set as long as the rigidity is 400 mg or less. This inorganic fiber paper has a density of 0.25 g / cm3 or more and 0.40 g / cm3 or less. Further, the density of the inorganic fiber paper is preferably from 0.28 g / cm3 to 0.39 g / cm3. If the density is less than 0.25 g / cm3, the fibers may become fluffy and the workability such as cutting and punching may be deteriorated. On the other hand, when the density exceeds 0.40 g / cm 3, it is difficult to sufficiently secure impregnation before firing.

  The thickness of the inorganic fiber paper can be arbitrarily set with respect to the basis weight as long as the density is 0.25 g / cm3 or more and 0.40 g / cm3 or less.

  This inorganic fiber paper has a liquid retention amount before firing of 100 g / m 2 or more. Further, the liquid retention amount before firing is preferably 120 g / m2 or more. If the liquid retention amount before firing is less than 100 g / m 2, the loading of the functional agent, the binder and the like becomes insufficient, and the function such as the adsorption performance and the physical strength may be inferior.

  The inorganic fiber paper of the present invention is manufactured by using a round paper machine, a fourdrinier paper machine, a short net paper machine, an inclined paper machine, a combination paper machine made of a combination of the same or different kinds of paper machines among these. It can be manufactured by a method. In the raw material slurry, in addition to the essential components, various anionic, nonionic, cationic or amphoteric retention improvers, drainage agents, dispersants, as necessary, as long as the desired effects of the present invention are not impaired. A paper strength improver and a viscosity agent can be appropriately selected and added. The raw material slurry is adjusted to a solid content concentration of about 0.1 to 5% by weight. In addition, it is also possible to appropriately add an internal additive such as a pH adjuster, an antifoaming agent, a pitch control agent, and a slime control agent according to the purpose.

  This raw material slurry is further diluted to a predetermined concentration to form a paper. The inorganic binder may form an aggregate using a coagulant depending on its shape, or may form an aggregate with a biosoluble ceramic fiber, glass fiber, or organic fiber. The coagulant includes a polymer coagulant and an inorganic coagulant, and can be appropriately selected in consideration of the components of the inorganic binder and the surface charge. The amount of the coagulant added can be changed depending on the type of the inorganic binder and the size of the desired aggregate. By controlling the size of the agglomerate, it is possible to make a paper without a small granular inorganic binder falling off from a papermaking wire. Next, the formed web is dried after removing excess moisture by a method such as suction or wet pressing. For drying, a drying device such as a Yankee dryer, a cylinder dryer, an air dryer, an infrared dryer, and a suction dryer can be used.

  The obtained inorganic fiber paper is impregnated with an impregnation liquid in which particles such as a catalyst or an adsorbent and an inorganic binder are dispersed. As the impregnating liquid, silica sol, silicate aqueous solution, alumina sol, zirconia sol and the like can be used.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples. In the examples, “%” indicates “% by weight” unless otherwise specified. The methods for measuring physical properties and the methods for measuring the average fiber diameter described in Examples and Comparative Examples are shown below.

1) Basis weight Measured according to the method described in JIS P8124. The unit is g / m2.

2) Thickness The thickness was measured by the method described in JIS P8118. The unit is μm.

3) Air permeability Measured according to the method described in JIS L1096. As a measuring device, a permeability tester No. manufactured by Toyo Seiki Seisaku-sho, Ltd. was used. 869 was used. The unit is cm3 / cm2 / sec.

4) Gurley stiffness Measured by the method described in JIS L1096 and JIS L1085. As a measuring device, Gurley rigidity tester No. manufactured by Toyo Seiki Seisaku-sho, Ltd. was used. 825 was used. The unit is mg.

5) Tensile strength in the MD direction (paper flow direction) The tensile strength in the MD direction was measured according to the method described in JIS P8113. Specifically, the tensile strength of a strip sample having a width of 15 mm and a length of 250 mm (the length direction is the MD direction) was measured. The unit is kN / m.

6) Wet tensile strength in MD direction (paper flow direction) Wet tensile strength in MD direction was measured according to the method described in JIS P8135. A strip sample having a width of 15 mm and a length of 250 mm (the length direction is the MD direction) is immersed in pure water at 25 ° C. for 3 minutes. The wet tensile strength of four strip samples subjected to the immersion treatment was measured together, and a value per one piece was calculated from the data measured for the four strip samples. The unit is kN / m.

7) Liquid holding amount before firing The dry weight (W1) of a sample having a size of 100 mm x 100 mm is measured. It was immersed in pure water at 25 ° C. placed on a vat for 15 seconds, taken out, and water droplets on the surface were scraped off with a glass rod, and the wet weight (W2) was measured. The unit is g / m2. This inorganic fiber paper has a liquid retention amount before firing of 100 g / m 2 or more.

8) Average fiber diameter Measured by a method based on ISO-16065-2. As a measuring machine, a fiber analyzer Metso FS5 manufactured by Metso Automation Co., Ltd. was used. The unit is μm.

  With respect to the inorganic fiber papers of Examples 1 to 5 and Comparative Examples 1 to 7, the composition of each component is shown in Table 1, and the results evaluated by the above-described evaluation tests are shown in Table 2.

(Example 1)
As shown in Table 1, biosoluble ceramic fibers (composition: SiO2 / CaO / MgO = 65/30/5; average fiber diameter 3 μm × length 600 μm, 45 μm or more shot content 10%), glass fiber 6 μm diameter × 6 mm length chopped strand glass fiber, NBKP as organic fiber (average fiber diameter 20 μm, 400 ml CSF) are added and mixed in water in a ratio of 40/40/20, and further, polyaluminum chloride (hereinafter, referred to as PAC) is added to the total fiber weight of 0.5%, sepiolite powder average particle diameter 7 μm) is added to the total fiber weight of 45%, and a 3% concentration raw material slurry is prepared. Done. The web was diluted with a Fourdrinier paper machine using this raw material slurry, the wet web was dehydrated with a press roll, and then heated and dried at 130 ° C. to obtain the inorganic fiber paper of Example 1.

(Example 2)
The paper-making was performed in the same manner as in Example 1 except that the mixing ratio of the biosoluble ceramic fiber, glass fiber, and organic fiber was set to 95/0/5, and sepiolite powder was added at 55% to the total weight of the fiber. Then, the inorganic fiber paper of Example 2 was obtained.

(Example 3)
Papermaking was performed in the same manner as in Example 1 except that NBKP having an average fiber diameter of 17 μm was used as the organic fiber, and the mixing ratio of the biosoluble ceramic fiber, glass fiber, and organic fiber was 20/25/55, respectively. The inorganic fiber paper of Example 3 was obtained.

(Example 4)
Papermaking was performed in the same manner as in Example 1 except that PVA (fiber length: 3 mm) having an average fiber diameter of 25 μm was used as the organic fiber, to obtain an inorganic fiber paper of Example 4.

(Example 5)
Papermaking was performed in the same manner as in Example 1 except that the mixing ratio of the biosoluble ceramic fiber, glass fiber, and organic fiber was 10/70/20, respectively, to obtain an inorganic fiber paper of Example 5.

(Comparative Example 1)
Papermaking was performed in the same manner as in Example 3 except that kaolin powder was added instead of the sepiolite powder, to obtain an inorganic fiber paper of Comparative Example 1.

(Comparative Example 2)
Papermaking was performed in the same manner as in Example 3 except that talc powder was added instead of the sepiolite powder, and an inorganic fiber paper of Comparative Example 2 was obtained.

(Comparative Example 3)
Papermaking was performed in the same manner as in Example 3 except that wollastonite powder was added instead of sepiolite powder, to obtain an inorganic fiber paper of Comparative Example 3.

(Comparative Example 4)
Papermaking was performed in the same manner as in Example 1 except that LBKP having an average fiber diameter of 10 μm was used as the organic fiber, to obtain an inorganic fiber paper of Comparative Example 4.

(Comparative Example 5)
As the organic fibers, PVA having an average fiber diameter of 40 μm (fiber length 3 mm) was used, and the mixing ratio of the biosoluble ceramic fibers, glass fibers, and organic fibers was set to 40/50/40, and the sepiolite powder was mixed with the fiber weight. Papermaking was performed in the same manner as in Example 1 except that 20% was added to the total amount of the above, to obtain an inorganic fiber paper of Comparative Example 5.

(Comparative Example 6)
Performed except that NBKP having an average fiber diameter of 17 μm was used as the organic fiber, the blending ratio of the biosoluble ceramic fiber, glass fiber, and organic fiber was 20/25/55, respectively, and no sepiolite powder was added. Papermaking was performed in the same manner as in Example 1 to obtain an inorganic fiber paper of Comparative Example 6.

(Comparative Example 7)
Papermaking was performed in the same manner as in Example 1 except that esparto having an average fiber diameter of 7 μm was used as the organic fiber, and the mixing ratio of the biosoluble ceramic fiber, glass fiber, and organic fiber was 20/25/55, respectively. The inorganic fiber paper of Example 7 was obtained.

  As shown in Table 2, it can be seen that in Examples 1 to 5, the density was adjusted to a suitable range and the impregnation before firing was excellent. Moreover, in Example 4 in which PVA was blended instead of NBKP as the organic fiber, the tensile strength was slightly lower, and it is understood that it is more preferable to blend only the cellulose fiber as the organic fiber.

  On the other hand, Comparative Example 1 in which kaolin was added instead of sepiolite and Comparative Example 2 in which talc was added instead of sepiolite both had too high densities and did not satisfy the liquid retention amount of 100 g / m 2 or more before firing. It turns out that impregnation is inferior. Comparative Example 3 in which wollastonite was added instead of sepiolite and Comparative Example 6 in which sepiolite was not added satisfied the density and the liquid retention before firing of 100 g / m2 or more, but had a very low air permeability. It turns out that it is difficult to apply to a product which requires high sealing performance.

  In both Comparative Examples 4 and 7, the average fiber diameter of the organic fibers was less than 17 μm, the density was too high, and the impregnating property was poor because the liquid retention amount before firing was not more than 100 g / m 2. . On the other hand, Comparative Example 5 in which the average fiber diameter of the organic fibers exceeds 25 μm satisfies a liquid retention amount of 100 g / m 2 or more before firing, but has a density of less than 0.25 g / cm 3 and a very low wet tensile strength. It is understood that the air permeability is high, and the Gurley stiffness exceeds 400 mg.

The inorganic fiber paper described above is a biosoluble ceramic fiber,
A glass fiber having a blending ratio of 0% by weight or more and 70% by weight or less in a fiber content,
Organic fibers having an average fiber diameter of 17 μm or more and 25 μm or less,
Aluminum sulfate, polyaluminum chloride, cationic colloidal silica, at least one or more cationic inorganic binders selected from alumina sol,
Sepiolite, and a sheet-formed substrate obtained by wet papermaking using,
It is characterized in that the density is 0.25 g / cm3 or more and less than 0.40 g / cm3, and the liquid retention amount before firing is 100 g / m2 or more.

  According to this inorganic fiber paper, by suppressing the density to less than 0.40 g / cm 3, the liquid retention amount before firing is set to 100 g / m 2 or more, and the impregnation property before firing can be improved. Furthermore, since the density is 0.25 g / cm3 or more, it is possible to suppress deterioration in workability such as cutting and punching. Moreover, while suppressing the density from becoming too high by setting the average fiber diameter of the organic fiber to 17 μm or more, it is possible to prevent the density from becoming too low by setting the average fiber diameter of the organic fiber to 25 μm or less. it can.

  The sepiolite is an inorganic binder that suppresses the density from becoming too high and lowers the air permeability. The glass fiber is effective in reducing the density, but when heat resistance is required, the mixing ratio in the fiber content can be set to 0% by weight. The fiber content includes biosoluble ceramic fibers, glass fibers, and organic fibers.

  Further, in this inorganic fiber paper, it is preferable that the organic fibers are made of only cellulose fibers.

  By forming the organic fiber only from the cellulose fiber and not compounding the synthetic resin fiber, it is possible to suppress a decrease in physical strength (tensile strength or wet tensile strength) and material cost.

  Further, in this inorganic fiber paper, the Gurley stiffness is preferably 400 mg or less.

  By setting the Gurley stiffness to 400 mg or less, bending becomes easy.

  Further, in this inorganic fiber paper, it is preferable that the air permeability is 3.5 cm3 / cm2 / sec or less.

  By doing so, it can be more suitably used especially for a product requiring a sealing property.

  Further, the inorganic fiber paper may be impregnated with an impregnating liquid.

  The impregnating liquid referred to here is a catalyst or an adsorbent for removing acidic gases such as volatile organic compounds (VOC), basic gases such as ammonia, sulfur oxides (SOx), nitrogen oxides (NOx), and chlorine. And the like, and dispersions of particles of a functional agent such as an inorganic binder. Specifically, silica sol, silicate aqueous solution, alumina sol, zirconia sol and the like can be exemplified.

Claims (2)

A biosoluble ceramic fiber;
A glass fiber having a blending ratio of 0% by weight or more and 70% by weight or less in a fiber content,
Organic fibers having an average fiber diameter of 17 μm or more and 25 μm or less,
Aluminum sulfate, polyaluminum chloride, cationic colloidal silica, at least one or more cationic inorganic binders selected from alumina sol,
An inorganic fiber paper, which is a sheet-formed base material obtained by wet papermaking using sepiolite having a blend ratio of 20% by weight or more and 60% by weight or less with respect to the fiber content. Inorganic fiber paper of claim 1, wherein the liquid retaining amount before firing is 100 g / m ² or more.