JP2018115409A - Inorganic fiber sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inorganic fiber sheet having excellent physical strength after firing.SOLUTION: An inorganic fiber sheet uses a glass fiber, an organic fiber, and a natural mineral fiber as the fiber content. The glass fiber and organic fiber sheets are impregnated with the natural mineral fiber.SELECTED DRAWING: None

Description

  The present invention relates to an inorganic fiber sheet excellent in physical strength after firing treatment.

  Inorganic fibers have excellent characteristics as industrial materials, and their use in all industries such as steel, petroleum, chemicals, electricity, automobiles, building materials, and aerospace has become established, heat-resistant catalyst support materials, heat-insulating materials, heat-resistant materials It is used in various applications such as filter media, heat-resistant insulating materials, heat-resistant seal materials, heat-resistant packing materials, heat-resistant buffer materials, and heat-resistant cushion materials.

  Inorganic fiber sheets using such inorganic fibers have already been used in various fields, and a typical example is a honeycomb-shaped gas adsorption element (see, for example, Patent Document 1). In this document, a honeycomb laminate is formed with paper made by mixing ceramic fibers, glass fibers, sepiolite and other clay minerals and an organic binder, and the organic binder is removed by firing treatment in a specific atmosphere. There has been proposed a method of manufacturing a honeycomb-shaped gas adsorbing element by impregnating a mixed dispersion of agent particles and an inorganic binder such as silica sol. In order to form a honeycomb-shaped gas adsorption element having good adsorption performance by the manufacturing method of Patent Document 1, it is necessary that the physical strength and liquid retention performance of the base material after the firing treatment are excellent. However, even when this method is used, there is a problem that physical strength such as tensile strength and wet tensile strength after the firing treatment is insufficient.

Japanese Patent No. 2925127

  This invention makes it a subject to provide the inorganic fiber sheet excellent in the physical strength after baking processing.

  The inorganic fiber sheet of the present invention that solves the above-mentioned object is an inorganic fiber sheet using glass fiber, organic fiber, and natural mineral fiber having an average fiber diameter of 1 to 30 μm as a fiber component. It is characterized by impregnating natural mineral fibers.

  According to the present invention, by impregnating a natural mineral fiber into an inorganic fiber sheet, the natural mineral fiber is present uniformly and densely in the sheet, so that physical strength such as tensile strength after firing treatment, wet tensile strength, etc. An improved inorganic fiber sheet can be provided.

  Hereinafter, the inorganic fiber sheet of the present invention will be described in detail. The inorganic fiber sheet of the present invention is composed of glass fiber, organic fiber, and natural mineral fiber, and is formed into a sheet obtained by wet-making glass fiber and organic fiber and then impregnating the natural mineral fiber. It is a material. The inorganic fiber sheet of the present invention can be suitably used for a heat-resistant catalyst support material, a heat insulating material, a heat-resistant filter material, a heat-resistant insulating material, a heat-resistant sealing material, a heat-resistant packing material, a heat-resistant buffer material, a heat-resistant cushioning material, and the like.

  1-30 mm is preferable, as for the fiber length of the glass fiber in this invention, 2-15 mm is more preferable, and 3-10 mm is still more preferable. If the fiber length is less than 1 mm, the physical strength after firing may be insufficient. On the other hand, when the fiber length exceeds 30 mm, the formation of the sheet base material is deteriorated, and the quality may vary. Moreover, it is preferable that the average fiber diameter of the glass fiber in this invention is 5-15 micrometers, 5-13 micrometers is more preferable, and 5-11 micrometers is still more preferable. If the average fiber diameter is less than 5 μm, the fibers are too thin to obtain a sufficient amount of impregnation with natural mineral fibers, and liquid retention properties cannot be obtained. On the other hand, if the average fiber diameter exceeds 15 μm, it becomes too thick and the gap between the fibers becomes large, the physical strength after firing is inferior, and the skin is irritating. There is a case.

  In the inorganic fiber sheet of the present invention, the glass fiber content is preferably 10 to 70% by weight. When the content is less than 10% by weight, the physical strength of the sheet base material before and after the baking treatment may be insufficient, and the liquid retention may be inferior. On the other hand, if it exceeds 70% by weight, the heat resistance may be deteriorated, the formation of the sheet base material may be deteriorated, the quality may vary, and pinholes due to fine holes may occur.

  The effects of the present invention can be achieved by using a pulp-like material made of cellulose fibers and synthetic resin short fibers as the organic fibers. In the heat-resistant inorganic sheet base material of the present invention, there is no particular limitation on the ratio of the pulp-like material composed of cellulose fibers in the organic fiber content and the synthetic resin short fibers, but if the blending ratio of the synthetic resin short fibers is large, the liquid retention However, the physical strength decreases and the cost also increases. On the other hand, when the blending ratio of the synthetic resin short fibers is low, the physical strength is increased, but the liquid retention is lowered. The content of the organic fiber, which is the sum of both the pulp-like material composed of cellulose fibers and the synthetic resin short fibers, is preferably 5 to 40% by weight, more preferably 5 to 30% by weight, and 5 to 20%. More preferably, it is% by weight. If the content is less than 5% by weight, the strength of the sheet base material at the time of wet papermaking may be insufficient and the sheet base material may not be manufactured after firing, or the liquid retention may be inferior due to a decrease in voids of the sheet base material after firing. If it exceeds 40% by weight, the voids of the sheet substrate after firing become too large, and the physical strength after firing may be inferior.

  Moreover, the organic fiber in this invention has an average fiber diameter of 25 micrometers or less. If the average fiber diameter of the organic fibers exceeds 25 μm, the density of the inorganic fiber sheet becomes too low, and the workability such as cutting and punching may be deteriorated.

  The pulp-like material composed of cellulose fibers used in the present invention is not limited to NBKP, LBKP, NBSP, LBSP or any other type of pulp, but NBKP is used in terms of the strength of the sheet base material during wet papermaking. Is more preferable. The freeness (Canadian standard freeness) is not particularly limited, but is preferably in the range of 200 to 700 ml CSF, more preferably in the range of 300 to 700 ml CSF, and in the range of 400 to 700 ml CSF. More preferably. If the freeness is less than 200 ml CSF, clogging may occur at the stage of forming the sheet base material by the wet papermaking method, the drainage may deteriorate, and a uniform texture may not be obtained. May increase and the liquid retention after firing may deteriorate. On the other hand, when it is 700 mlCSF or more, the fineness of the fibers is poor, the entanglement is inferior, the physical strength is inferior, and the sheet base material may not be successfully made.

  Examples of the resin constituting the synthetic resin short fiber used in the present invention include polyvinyl alcohol resins, polyester resins, polyolefin resins, acrylic resins, polyvinyl acetate resins, ethylene-vinyl acetate copolymer resins, polyamide resins. 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, and the like. Among these, when at least one synthetic resin short fiber selected from polyvinyl alcohol resin, polyester resin, polyolefin resin, and acrylic resin is used, an appropriate void can be formed in the sheet base material after firing. As a result, well-balanced physical strength and liquid retention can be provided.

  The fiber diameter of the synthetic resin short fiber used in the present invention is preferably 2 to 20 μm, more preferably 3 to 15 μm, and still more preferably 4 to 12 μm. If the fiber diameter of the synthetic resin short fibers is less than 2 μm, the voids of the sheet base material after firing cannot be sufficiently secured, and the liquid retention may be inferior. On the other hand, if it exceeds 20 μm, the voids of the sheet base material after firing are too large, the adhesion points between the glass fibers are reduced, and the physical strength may be inferior.

The fiber length of the synthetic resin short fiber used in the present invention is preferably 0.4 to 20 mm, more preferably 1 to 15 mm, and further preferably 1 to 6 mm. When the fiber length is less than 0.4 mm, the physical strength of the sheet base material during wet papermaking may be low, and the sheet base material may be damaged. On the other hand, when the fiber length exceeds 20 mm, the fibers may be entangled, resulting in uneven thickness or poor formation.
In addition to these fibers, various fibers can be used as needed. Representative examples of fibers include ceramic fibers, rock fibers (rock wool), mineral slag fibers, silicate fibers such as potassium titanate fibers, metal fibers, carbon fibers, etc. Fiber.

  Examples of natural mineral fibers used for impregnation include sepiolite, wollastonite, and attapulgite. Each main component is sepiolite magnesium silicate salt, wollastonite calcium silicate salt, and attabargite is basically magnesium silicate salt, but magnesium is partially replaced with aluminum or iron. These natural inorganic fibers generally have good heat resistance and high strength after firing, and are widely used for applications such as heat insulation.

  Sepiolite is preferably used among natural mineral fibers. Sepiolite is a clay-like mineral having a large number of active hydroxyl groups on the surface made of magnesium silicate. The shape is not limited in any way, and in addition to the fiber shape, any of a block shape, a mud shape, and a powder shape can be used. Further, talc, calcite, dolomite, magnesite, basic magnesium carbonate, silicic acid component, etc. may be contained as a host rock or intercalated stone. There are no particular restrictions on the country of origin such as Spain, Turkey, or China.

  The content of the natural mineral fiber in the inorganic fiber sheet of the present invention is preferably 20 to 80% by weight with respect to the fiber (glass fiber or organic fiber) constituting the sheet substrate, and is 25 to 70% by weight. More preferably, it is more preferably 30 to 60% by weight. If the content is less than 20% by weight, the physical strength after firing may be insufficient. If it exceeds 80% by weight, the liquid absorbency after firing may be deteriorated, or powder may fall off from the sheet base material. It may get worse.

  An inorganic binder can be used for the inorganic fiber sheet of the present invention. By including the inorganic binder, the physical strength can be further improved. Examples of the inorganic binder include cationic inorganic binders such as aluminum sulfate, polyaluminum chloride, cationic colloidal silica, and alumina sol, and anionic inorganic binders such as colloidal silica and silica sol.

  As a content rate of an inorganic binder, 0.1 to 5 weight% is preferable with respect to the total amount of fiber weight, 0.1 to 3 weight% is more preferable, and 0.1 to 1 weight% is further more preferable. When the content of the inorganic binder is less than 0.1% by weight, the physical strength after firing may be inferior. On the other hand, if the content of the inorganic binder exceeds 5% by weight, aggregation may become too strong, resulting in poor formation and poor liquid absorption.

The basis weight of the inorganic fiber sheet of the present invention is preferably 50 g / m ² or more and 100 g / m ² or less. If it is less than 50 g / m < ² >, the physical strength of the inorganic fiber sheet at the time of wet papermaking may be inferior. On the other hand, if it exceeds 100 g / m ² , depending on the product to be applied, it may be too heavy and handleability may be inferior.

  The thickness of the inorganic fiber sheet of the present invention is preferably 120 μm or more and 330 μm or less, and more preferably 150 μm or more and 300 μm or less. When the thickness of the inorganic fiber sheet is less than 120 μm, it is difficult to ensure a sufficient amount of liquid retention, and when the thickness of the inorganic fiber sheet is greater than 330 μm, the physical strength may be inferior.

Inorganic fiber sheet of the present invention preferably has a density of less 0.25 g / cm ³ or more 0.40 g / cm ^3, more preferably at most 0.28 g / cm ³ or more 0.39 g / cm ³ . If the density is less than 0.25 g / cm ³ , the fibers may become fuzzy and processability such as cutting and punching may be deteriorated. On the other hand, if the density exceeds 0.40 g / cm ³ , it is difficult to ensure sufficient liquid impregnation properties when the liquid is impregnated before firing.

  The inorganic fiber sheet of the present invention is a sheet using a circular paper machine, a long paper machine, a short paper machine, a slanted paper machine, a combination paper machine in which the same or different types of paper machines are combined. After being made into a sheet, it can be produced by impregnation. In the raw material slurry used for papermaking, in addition to glass fiber and organic fiber, which are essential components, various anionic, nonionic, cationic or amphoteric substances are added as necessary within a range not damaging the desired effect of the present invention. A yield improver, a drainage agent, a dispersant, a paper strength improver and a sticking 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, internal additives such as a pH adjuster, an antifoaming agent, a pitch control agent, and a slime control agent can be appropriately added depending on the purpose.

  This raw material slurry is further diluted to a predetermined concentration to make paper. Moreover, you may form the aggregate of glass fiber or organic fiber using a flocculant. The flocculant includes a polymer flocculant and an inorganic flocculant, and can be appropriately selected in consideration of the surface charge of glass fiber or organic fiber. The amount of the flocculant added can be changed depending on the type of glass fiber or organic fiber and the size of the desired aggregate. By controlling the size of the agglomerates, papermaking can be performed without glass fibers or organic fibers falling off the 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, or a suction dryer can be used.

  The obtained inorganic fiber sheet is impregnated in an impregnating liquid in which natural mineral fibers are dispersed. In addition to natural mineral fibers, the impregnating liquid contains volatile organic compounds (VOC), basic gases such as ammonia, sulfur oxides (SOx), nitrogen oxides (NOx), chlorine, etc., as long as the physical strength is not impaired. A dispersion of particles of a functional agent such as a catalyst or an adsorbent for removing the acid gas and a dispersion of an inorganic binder can be mixed. Specific examples include silica sol, silicate aqueous solution, alumina sol, zirconia sol, and the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples. In the examples, “parts” means “parts by weight” unless otherwise specified. The measuring method of the physical property described in the Example and the comparative example was shown below.

1) Basis weight It measured by the method of JISP8124. The unit is g / m ² .

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

3) 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. A strip sample of 15 mm width x 250 mm length (length direction is MD direction) was measured with one piece before firing, and after firing, 4 pieces were collected and the tensile strength was measured to calculate the value per piece. did. The unit is kN / m.

4) 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 of 15 mm width × 250 mm length (length direction is MD direction) was cut out, and before firing, the four pieces were immersed in pure water at 25 ° C. for 3 minutes, and the four strip samples subjected to the immersion treatment were wet together. Measure the tensile strength. After firing, the 8 pieces are immersed for 2 hours, and the 8 strip samples subjected to the immersion treatment are collected and the wet tensile strength is measured. A value per piece was calculated from the measured data. The unit is kN / m.

  Table 1 shows the results of the evaluation tests described above for the inorganic fiber sheets of Examples 1 to 3 and Comparative Examples 1 and 2.

Example 1
6 μm diameter × 6 mm long chopped strand glass as glass fiber, NBKP (average fiber diameter 20 μm, 400 ml CSF) as organic fiber, 85 parts and 30 parts, respectively, and then added and mixed in water, and alumina sol as inorganic binder 0.5 parts of (Nissan Chemical Co., Ltd.) was added to prepare a 3% concentration raw material slurry. The raw slurry was used to dilute the web with a long paper machine, and the wet web was dehydrated with a press roll and then heat dried at 130 ° C. to form a sheet. Further, the obtained sheet was impregnated with an 8 mass% aqueous dispersion of sepiolite for 30 seconds, the impregnated sheet was dehydrated with a press roll, and then heat-dried at 130 ° C. to obtain an inorganic fiber sheet of Example 1. It was. It was 19 g / m ² when the impregnation amount of sepiolite was calculated from the basis weight before and after impregnation treatment with sepiolite. Further, after measuring the thickness, tensile strength and wet tensile strength, the tensile strength and wet tensile strength of the inorganic fiber sheet fired at 500 ° C. for 1 hour were measured.

(Comparative Example 1)
Papermaking was carried out in the same manner as in Example 1 except that sepiolite was not impregnated, and an inorganic fiber sheet of Comparative Example 1 was obtained. After measuring the basis weight, thickness, tensile strength, and wet tensile strength of the inorganic fiber sheet, the tensile strength and wet tensile strength of the inorganic fiber sheet fired at 500 ° C. for 1 hour were measured.

(Comparative Example 2)
6 μm diameter × 6 mm long chopped strand glass as glass fiber, NBKP (average fiber diameter 20 μm, 400 ml CSF) as organic fiber, 85 parts and 30 parts respectively, were added and mixed sequentially in water, and sepiolite powder was further mixed. 50 parts was added to prepare a raw material slurry having a concentration of 3%. The raw slurry was used to dilute the web with a long paper machine, and the wet web was dehydrated with a press roll, and then heat-dried at 130 ° C. to form a sheet. After measuring the basis weight, thickness, tensile strength, and wet tensile strength of the obtained sheet, the tensile strength and wet tensile strength of the inorganic fiber sheet fired at 500 ° C. for 1 hour were measured.

As shown in Table 1, in Example 1, by impregnating with sepiolite, the tensile strength after baking at 500 ° C. and the wet tensile strength were compared with Comparative Example 1 in which sepiolite was not impregnated, and the comparison with sepiolite internally added It can be seen that it is superior to Example 2.

Claims (2)

  An inorganic fiber sheet using glass fiber, organic fiber, and natural mineral fiber as a fiber component, wherein the glass fiber and organic fiber sheet are impregnated with natural mineral fiber.   The manufacturing method of the inorganic fiber sheet of Claim 1.