JP2018115408A - Inorganic fiber paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inorganic fiber paper that shows improvements in pre-firing impregnability and processing suitability.SOLUTION: An inorganic fiber paper is a sheeted substrate obtained by wet papermaking using a glass fiber, an organic fiber with a Runkel ratio of 1.5 or less and an average fiber diameter of 17 μm or more and 25 μm or less, at least one cationic inorganic binder selected from aluminum sulfate, polyaluminium chloride, cationic colloidal silica, and alumina sol, and sepiolite. Before fired, the inorganic fiber paper can retain liquid of 100 g/mor more in volume.SELECTED DRAWING: None

Description

  The present invention relates to an inorganic fiber paper relating to an inorganic fiber sheet excellent in liquid retention and bending workability before firing.

  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.

  Although heat-resistant inorganic fiber sheet base materials using inorganic fibers have already been used in various fields, a honeycomb-shaped gas adsorption element can be cited as a representative application (see, for example, Patent Document 1). In order to form a honeycomb-shaped gas adsorbing element having good adsorption performance by this production method, the physical strength and liquid retention performance of the base material after firing must be excellent. However, there is a problem that even if such a measure is taken, it is impossible to form a sheet having satisfactory physical strength and liquid retention after firing.

  Various methods have been proposed for the heat-resistant inorganic fiber sheet substrate. As a method for improving the physical strength of the fired sheet, it is formed into a sheet by a wet papermaking method using heat-resistant inorganic fibers and an inorganic binder component as essential components, and the sheet is fired at a temperature of 400 ° C. or higher, and further an inorganic binder. A method of adding components has been proposed (see, for example, Patent Document 2).

Japanese Patent No. 2925127 JP 2001-262468 A

  Inorganic fiber paper using glass fibers as inorganic fibers tends to have a lower density than inorganic fiber paper using amorphous refractory ceramic fibers (hereinafter referred to as RCF), and can be used for cutting, punching, bending, etc. It may be inferior in workability. On the other hand, if the density is unnecessarily increased, the impregnation property deteriorates, and it becomes difficult to impregnate an impregnating liquid composed of a dispersion of particles of a functional agent such as a catalyst or an adsorbent or a dispersion of an inorganic binder. There is a risk that it may be difficult to carry the substrate sufficiently.

  Here, since the organic component disappears when the inorganic fiber paper is fired, the strength is lowered and the handling property is deteriorated after firing. Furthermore, the sheet-like state before firing is more easily impregnated with the impregnating liquid than after firing after forming such as bending. In these respects, it is advantageous to impregnate the inorganic fiber paper before firing with the impregnating liquid rather than impregnating the inorganic fiber paper after firing with the impregnating liquid, but compared with after the firing in which the organic components disappear and voids are generated. It is difficult to ensure the impregnation property before firing, and the impregnation property before firing is not considered.

  An object of the present invention is to provide an inorganic fiber paper having improved impregnation properties and processability before firing, focusing on the point of impregnation with an impregnation liquid before firing in inorganic fiber paper using glass fibers.

The inorganic fiber paper of the present invention that solves the above-mentioned object is a glass fiber, an organic fiber having a Runkel ratio of 1.5 or less and an average fiber diameter of 17 μm or more and 25 μm or less, aluminum sulfate, polyaluminum chloride, cationic colloidal silica, It is a base material formed into a sheet obtained by wet papermaking using at least one cationic inorganic binder selected from alumina sol and sepiolite, and has a liquid retention amount of 100 g / m ² or more before firing. It is characterized by being.

  According to the inorganic fiber paper of the present invention, when the average fiber diameter of the organic fibers is 17 μm or more and 25 μm or less, if the Runkel ratio is larger than 1.5, the liquid retention before firing is preferably improved, but on the other hand, cutting Processing suitability such as punching, punching, and bending deteriorates. Conversely, by setting the Runkel ratio of the organic fiber to 1.5 or less, it is possible to prevent the density from becoming too low, and to give workability such as cutting, punching, bending, etc. while maintaining the liquid retention amount before firing. Can do.

  The sepiolite is an inorganic binder necessary for suppressing the density from becoming too high and maintaining the shape after firing.

  Moreover, in the inorganic fiber paper of the present invention, it is preferable that the organic fiber is composed only of cellulose fiber. By constituting the organic fiber only from the cellulose fiber and not blending the synthetic resin fiber, it is possible to suppress a decrease in physical strength (tensile strength and wet tensile strength) and material cost.

  Furthermore, the inorganic fiber paper of the present invention may be impregnated with an impregnation liquid.

  The impregnating liquid here is a catalyst or adsorbent for removing acidic gases such as volatile organic compounds (VOC), basic gases such as ammonia, sulfur oxides (SOx), nitrogen oxides (NOx), and chlorine. For example, a dispersion in functional agent particles, a dispersion of an inorganic binder, and the like. Specific examples include silica sol, silicate aqueous solution, alumina sol, zirconia sol, and the like.

  According to the present invention, by using organic fibers whose average fiber diameter and Runkel ratio are adjusted to suitable ranges, an inorganic material having improved processability such as cutting, punching and bending while improving impregnation properties before firing. Fiber paper 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-formed substrate obtained by wet papermaking using a cationic inorganic binder and sepiolite as glass fibers, organic fibers, and inorganic binders. The inorganic fiber paper 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.

  The glass fiber in the present invention preferably has a fiber length of 1 mm to 30 mm. If the fiber length is less than 1 mm, the physical strength may be insufficient. On the other hand, when the fiber length exceeds 30 mm, the formation of the inorganic fiber paper 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 micrometers or more and 15 micrometers 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 and the gap between fibers becomes large, the physical strength is inferior, and the skin is irritating. is there.

  As the organic fiber in the present invention, a pulp-like material made of cellulose fiber and a synthetic resin short fiber can be used, and each can be used alone or in combination. However, the physical strength can be improved and the cost can be reduced by constituting the organic fiber only from the cellulose fiber.

  Moreover, the organic fiber in the present invention has a Runkel ratio of 1.5 or less. When the Runkel ratio is larger than 1.5, the fibers are less likely to be crushed and the amount of liquid retained before firing is preferably improved, but on the other hand, the workability such as cutting, punching and bending is deteriorated. Conversely, by setting the Runkel ratio of the organic fiber to 1.5 or less, the fiber is liable to be crushed, the density is prevented from becoming too low, and the liquid retention amount before firing is secured, while cutting, punching, bending, etc. Workability can be imparted.

  The organic fiber in the present invention preferably 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 property before firing may be deteriorated. On the other hand, if 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 deteriorates and the physical strength decreases.

  The pulp-like material made 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, broadleaf sulfite pulp, Neither esparto nor any other kind of pulp is used, 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 to 700 ml CSF, more preferably in the range of 300 ml CSF to 700 ml CSF, more preferably 400 ml CSF to 700 ml CSF. More preferably, it is in the range. If the freeness is less than 200 ml CSF, the inorganic fiber paper may become clogged at the stage of forming the inorganic fiber paper by the wet papermaking method, the drainage may deteriorate, and a uniform texture may not be obtained. May become too high. On the other hand, if it is higher than 700 ml CSF, the fineness of the fibers is poor, the entanglement is inferior, the physical strength is inferior, and the inorganic fiber paper may not be successfully made.

  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 alumina sol stabilizer 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 shape or a plate-like structure, and any shape may be used. The blending 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 amount of the fiber weight, More preferably, the content is from 1% by weight to 1% by weight. When the blending ratio of the cationic inorganic binder is less than 0.1% by weight, the wet tensile strength may be inferior. On the other hand, when the blending ratio of the cationic inorganic binder exceeds 5% by weight, aggregation may become too strong, resulting in poor formation or poor liquid absorption.

  Sepiolite in the present invention is a clay mineral having a large number of active hydroxyl groups on the surface made of hydrous magnesium silicate, and is not limited in its shape at all. In addition to fibrous, any of lump, mud, powder Can also be used. Moreover, talc, calcite, dolomite, magnesite, basic magnesium carbonate, silicic acid component, etc. as a host rock or intercalation stone may be contained. There are no particular restrictions on the country of origin such as Spain, Turkey, or China.

The mixing ratio of sepiolite used in the present invention is preferably 20% by weight or more and 60% by weight or less, and 25% by weight or more and 55% by weight or less with respect to the fiber (glass fiber or organic fiber) constituting the inorganic fiber paper. More preferably, it is more preferably 45% by weight or more and 55% by weight or less. When the blending ratio is less than 20% by weight, the physical strength may be insufficient, and when the blending ratio exceeds 60% by weight, powder falling from the inorganic fiber paper may be deteriorated.
Moreover, you may mix | blend other natural mineral fibers, such as a wollastonite and attapulgite, with sepiolite which is one of the natural mineral fibers. In addition, for example, a clay mineral, colloidal silica, lithium silicate, or the like usually called mountain cork, mountain leather, mountain wood, or the like, such as palygorskite, may be appropriately selected and used.

The basis weight of the inorganic fiber paper of the present invention can be arbitrarily set as long as the processability is not affected. The inorganic fiber paper of the present invention preferably has a density of 0.25 g / cm ³ or more and 0.40 g / cm ³ or less. 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 becomes difficult to ensure sufficient impregnation properties before firing.

The thickness of the inorganic fiber paper of the present invention can be arbitrarily set with respect to the basis weight as long as the density is 0.25 g / cm ³ or more and 0.40 g / cm ³ or less.

The inorganic fiber paper of the present invention is characterized in that the liquid retention amount before firing is 100 g / m ² or more. Moreover, it is preferable that the liquid retention amount before baking is 120 g / m < ² > or more. When 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 adsorption performance and physical strength may be inferior.

  The inorganic fiber paper of the present invention is manufactured using a circular paper machine, a long paper machine, a short paper machine, an inclined paper machine, a combination paper machine in which the same or different types of paper machines are combined, and the like. Can be manufactured by a method. In the raw material slurry, in addition to the essential components, various anionic, nonionic, cationic or amphoteric yield improvers, filtering agents, and dispersants may be used as long as the desired effects of the present invention are not impaired. 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. The inorganic binder may form an aggregate using a flocculant depending on its shape, or may form an aggregate with a biosoluble ceramic fiber, glass fiber, or organic fiber. The flocculant includes a polymer flocculant and an inorganic flocculant, and can be appropriately selected in consideration of the components of the inorganic binder and the surface charge. The addition amount of the flocculant can be changed depending on the kind of the inorganic binder and the desired size of the aggregate. By controlling the size of the agglomerates, papermaking can be performed without falling off the papermaking wire even with a small granular inorganic binder. 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 paper is impregnated with an impregnating 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, or the like can be used.

  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, “%” indicates “% by weight” unless otherwise specified. The measuring method of the physical property described in the Example and the comparative example, and the measuring method of an average fiber diameter were 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) Density The value obtained by dividing the rice tsubo by the thickness was used. The unit is g / cm ³ .

4) Runkel ratio A pulp sheet used for inorganic fiber paper production was cut, and its cross section was observed with an electron microscope, and the fiber diameter, fiber lumen, and average length of fiber cell walls of about 50 fiber cross sections were determined. The Runkel ratio is a value obtained by dividing twice the thickness of the cell wall of the fiber by the width of the cell lumen. When the thickness of the fiber cell wall is H and the length of the cell lumen is L, it is expressed by the following equation. .
R = 2H / L
R is 1.5 or less.

5) Tensile strength in MD direction (paper flow direction) Tensile strength in MD direction was measured according to the method described in JIS P8113. Specifically, the tensile strength of a strip sample of 15 mm width × 250 mm length (length direction is 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 in accordance with the method described in JIS P8135. A strip sample of 15 mm width × 250 mm length (length direction is MD direction) is immersed in pure water at 25 ° C. for 3 minutes. Four strip samples subjected to the immersion treatment were collectively measured for wet tensile strength, and the value per piece was calculated from the data measured for the four strip samples. The unit is kN / m.

7) Liquid retention amount before baking The dry weight (W1) of a 100 mm x 100 mm size sample is measured. After dipping for 15 seconds in pure water of 25 ° C. stretched on a bat and scraping off the water droplets on the surface with a glass rod, the wet weight (W2) was measured, and the liquid retention amount was determined from W1 and W2. The unit is g / m ² . The inorganic fiber paper of the present invention is characterized in that the liquid retention amount before firing is 100 g / m ² or more.

8) Suitability for bending work Ease of crease when a 100 mm × 100 mm size sheet sample was folded in two was visually evaluated.
○ ... Folded creases × ... Folded

Example 1
6 μm diameter × 6 mm long chopped strand glass fiber as glass fiber, NBKP (runkel ratio 0.9, average fiber diameter 20 μm, 400 ml CSF) as organic fiber were each added to and mixed in water sequentially with 95/30, 0.5% of polyaluminum chloride (hereinafter referred to as PAC) as an inorganic binder is added to the total amount of fiber weight, and sepiolite powder (average particle size 7 μm) is added to 55% of the total amount of fiber weight. Then, a raw material slurry having a concentration of 3% was prepared. Using this raw material slurry, the web was diluted with a long paper machine, the wet web was dehydrated with a press roll, and then heat-dried at 130 ° C. to obtain an inorganic fiber paper of Example 1.

(Example 2)
6 μm diameter × 6 mm long chopped strand glass fiber as glass fiber, NBKP (Lunkel ratio 1.1, average fiber diameter 20 μm, 400 ml CSF) as organic fiber, blend ratio of organic fiber 95/30 respectively, sepiolite powder as fiber Papermaking was carried out in the same manner as in Example 1 except that 55% of the total weight was added, and an inorganic fiber paper of Example 2 was obtained.

(Comparative Example 1)
Papermaking was performed in the same manner as in Example 1 except that NBKP (Runkel ratio 1.7, average fiber diameter 17 μm, 400 ml CSF) was added as an organic fiber, and an inorganic fiber paper of Comparative Example 1 was obtained.

  As shown in Table 1, in Examples 1 and 2, it is found that the impregnation property before firing is excellent and the bending workability is also excellent. On the other hand, in Comparative Example 1 using an organic fiber having a Runkel ratio of 1.7, the impregnation property before firing was excellent, but it was found that the bending workability was insufficient.

Claims (1)

An organic fiber having a glass fiber and Runkel ratio of 1.5 or less and an average fiber diameter of 17 μm to 25 μm, and at least one cationic inorganic binder selected from aluminum sulfate, polyaluminum chloride, cationic colloidal silica, and alumina sol; An inorganic fiber paper characterized in that it is a sheet-formed base material obtained by wet papermaking using Sepiolite, and the liquid retention amount before firing is 100 g / m ² or more.