JPH0316436B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a high-density inorganic fiber sheet using a papermaking method. [Prior Art] Inorganic fiber sheets made of, for example, glass fibers obtained using a paper-making method usually have a binder content of 0.22 g/min when the amount of binder added is 20% or less. It is usually manufactured as a low-density sheet filled with voids of cm ³ or less, and although it is suitable for applications that take advantage of the high porosity of the sheet, it is not suitable for applications in fields where high density is required. The reality is that, for example, inorganic fiber sheets that can be used as face materials for composite-type printed circuit boards and heat-insulating foam resin boards are not fully satisfactory. For example, when using an inorganic fiber sheet made by the conventional papermaking method for a composite type printed circuit board, the sheet is bulky and low density, so it is difficult to press in the prepreg lamination press process after resin impregnation. The number of sheets loaded into the machine must be reduced, and since the laminates obtained by molding inevitably have a high resin impregnation ratio, they are prone to warping and twisting, and are prone to warping and twisting when heated. It has disadvantages such as insufficient dimensional stability at the bottom. For this reason, as a method of filling the voids between inorganic fibers in a glass fiber sheet etc. with an inorganic filler etc. to obtain a high density sheet with a low resin impregnation rate, for example, Japanese Patent Application Laid-open No. 54-50583 describes a ready-made method. A method has been proposed in which glass fiber nonwoven fabric is impregnated with an inorganic filler. [Problems to be Solved by the Invention] However, a method in which a subsequent step of impregnating or coating a ready-made inorganic fiber sheet obtained in the first step with a slurry containing an inorganic filler is difficult to achieve in the manufacturing process. Since it is a two-step process,
Not only is it uneconomical in terms of equipment and energy consumption, but it is also necessary to add additives to the slurry in order to prevent the inorganic filler from impregnating the slurry or from settling in the slurry during the coating process. A sticky agent must be added, and depending on the use of the obtained inorganic fiber sheet, the use of a disliked additive may become unavoidable. In addition, there is a method for obtaining a sheet in which a filler is embedded in an inorganic fiber sheet by a paper-making method, that is, by forming an inorganic fiber slurry containing a powdered filler, the filler is embedded in the sheet. In the method of obtaining an inorganic fiber sheet,
It is difficult to retain the filler at a good yield, and a high-density inorganic fiber sheet cannot be obtained. That is, inorganic flocculants such as aluminum sulfate and ionic polymer flocculants such as polyacrylamide, which are commonly used when obtaining filler-containing paper from pulp raw materials, are added to a slurry of inorganic fibers. Even if the paper is made, it is difficult to fix the filler to the inorganic fibers with a good yield because the filler falls off the wire during the papermaking process.Furthermore, the fixation of the filler in the inorganic fiber slurry is poor and the filler settles. So this is
Unavoidable disadvantages include uneven distribution of the filler in the obtained inorganic fiber sheet and deterioration of the quality of the sheet. In contrast, the present invention utilizes a mixture of small-diameter inorganic fibers as a fiber component, and uses a cationic polymer substance, an anionic polymer substance, or a cationic polymer substance as a filler fixing agent. By using a polymer material consisting of a combination of a molecular material and a nonionic polymer material, the filler in the slurry is efficiently fixed on the small-diameter inorganic fibers, and a high-density inorganic fiber sheet can be obtained by the papermaking method. provide a method. [Means for Solving the Problems] The method for producing an inorganic fiber sheet of the present invention is based on 100 parts by weight of inorganic fibers containing 5% by weight or more of small-diameter inorganic fibers with an average fiber diameter of 3 μ or less. For papermaking, 50 to 300 parts by weight of filler and a fixing agent made of a combination of a cationic polymeric substance and an anionic polymeric substance, or a combination of a cationic polymeric substance and a nonionic polymeric substance are added. This process consists of a step of preparing an aqueous slurry, and a step of dewatering and papermaking the obtained aqueous slurry for papermaking. In the method for producing an inorganic fiber sheet of the present invention having the above-mentioned structure, the inorganic fiber component used in the aqueous slurry includes the same fibers as the various inorganic fibers used to obtain a normal inorganic fiber sheet, for example. , glass fiber, ceramic fiber, rock wool, alumina fiber, carbon fiber, etc. are used. The fine inorganic fibers blended in an amount of 5% by weight or more in the inorganic fibers have a sufficient surface area to increase the fixation yield of the filler. When the average fiber diameter exceeds 3 μ, a sufficient surface area cannot be obtained by the small-diameter inorganic fibers, and the fixing yield of the filler decreases. For this reason, the small-diameter inorganic fibers that account for 5% by weight or more of the inorganic fibers have an average fiber diameter of 3 μ or less, preferably 1 μ or less. Furthermore, if the above-mentioned small-diameter inorganic fibers are less than 5% by weight based on the total inorganic fibers, the effect of improving the fixation yield of filler by the small-diameter inorganic fibers will not be sufficient, and a high-density inorganic fiber sheet will not be obtained. . The fillers added to the aqueous slurry include common fillers used as fillers for paper and plastic molded products, such as aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, kaolin, clay, talc, Inorganic powders such as titanium oxide, silica, wollastonite, potassium titanate, glass powder, organic powders such as urea/formalin resin powder, epoxy resin powder, phenol resin powder, and metal powders such as aluminum powder, etc. is used. If the amount of filler in the aqueous slurry is less than 50 parts by weight per 100 parts by weight of inorganic fibers, it will be difficult to obtain an inorganic fiber sheet with a sufficiently high density;
If it exceeds 300 parts by weight, the fiber component in the resulting inorganic fiber sheet will decrease, making it impossible to obtain an inorganic fiber sheet with sufficient strength. In the method for producing an inorganic fiber sheet of the present invention, a cationic polymer substance and an anionic polymer substance or a cationic polymer substance are used as fixing agents to effectively fix the filler in the aqueous slurry to the small diameter inorganic fibers. A plurality of polymeric substances are used in combination with a substance and a nonionic polymeric substance. Note that typical polymeric substances used as fixing agents are as follows. Cationic polymer substances such as cation-modified polyacrylamide, cation-modified starch, polyamide/polyamine/epichlorohydrin resin, polyethyleneimine, etc., anionic polymer substances such as anion-modified polyacrylamide, starch and its derivatives, polyvinyl alcohol, and even
For example, homopolymers made of various monomers having carboxyl or sulfonic groups such as acrylic acid, methacrylic acid, maleic acid or its anhydride, fumaric acid, itaconic acid, vinyl sulfonic acid or their salts, or Copolymers of monomers with other copolymerizable monomers, such as ethylene, butylene, diisobutylene, decene, dodecene, acrylonitrile, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, styrene, vinyl acetate, etc. , nonionic polymeric substances Nonionic modified polyacrylamide, hydroxyethyl cellulose, guar gum, etc. Addition of a fixing agent to an aqueous slurry made of inorganic fibers is, for example, a fixing agent consisting of a combination of a cationic polymeric substance and an anionic polymeric substance. In the case of an agent, the anionic polymeric substance may be added after the cationic polymeric substance is added;
In the case of a fixing agent consisting of a combination of a cationic polymeric substance and a nonionic polymeric substance, the point of the fixing effect of the fixing agent is to add the cationic polymeric substance after adding the nonionic polymeric substance. It has been confirmed that favorable results can be obtained. A fixing agent consisting of a combination of a cationic polymeric substance and an anionic polymeric substance, or a fixing agent consisting of a combination of a cationic polymeric substance and a nonionic polymeric substance, has a ratio of 0.1 to With an addition amount of about 1% by weight,
Sufficient fixing effect is exhibited. As mentioned above, in the method for producing an inorganic fiber sheet of the present invention, a fixing agent consisting of a combination of a cationic polymeric substance and an anionic polymeric substance,
Alternatively, a fixing agent made of a combination of a cationic polymeric substance and a nonionic polymeric substance is used, and in particular, a fixing agent made of a combination of a cationic polymeric substance and a nonionic polymeric substance is used. In some cases, a test to measure the fixation rate of fillers using a Dynamic Drainage Jar shows that a high fixation effect is exhibited even under hydraulic shear force. An aqueous slurry containing a filler and a fixing agent is introduced into the drainage jar of a dynamic freeness tester, and after applying a wide range of hydraulic shear force using a stirring blade that rotates at high speed, This has been clarified by a test to measure the fixation rate of the filler, which consists of collecting the filler that has fallen out with a filter paper and quantifying it. The type of aqueous slurry used in the above-mentioned filler fixation rate measurement test and the obtained filler fixation rate will be explained. Preparation of aqueous slurry After obtaining a dispersion with a glass fiber concentration of 0.05% by weight using 50 parts by weight of glass fibers with an average fiber diameter of 9μ and 50 parts by weight of small diameter glass fibers with an average fiber diameter of 0.7μ, Furthermore, 120 parts by weight of clay powder was added, and then 10 parts by weight of fibrous polyvinyl alcohol as a binder component and the fixing agent listed in the specified column of Table 1 were sequentially added. An aqueous slurry was prepared by stirring for 1 minute.

【table】

Table 2 Table 2 also shows the filler fixation rate (yield (%)) of each aqueous slurry, along with the stirring speed at which the aqueous slurry was obtained.

[Table] Further, the aqueous slurry obtained by stirring at the above-mentioned stirring speed of 500 rpm was subjected to manual papermaking in a conventional manner to obtain an inorganic fiber sheet. The basis weight and density of each obtained inorganic fiber sheet are shown in Table 3 (Part 1).

【table】

[Table] In addition, the aqueous slurry obtained by stirring at the above-mentioned stirring speed of 1500 rpm (under high shear force) was subjected to manual papermaking in a conventional manner to obtain an inorganic fiber sheet. The basis weight and density of each obtained inorganic fiber sheet are shown in Table 3 (Part 2).

[Effect]

In the method for producing inorganic fibers of the present invention, inorganic fibers containing 5% by weight or more of small-diameter inorganic fibers with an average fiber diameter of 3 μ or less are used as the inorganic fiber component, and 100% by weight of this inorganic fiber is used. 50 to 300 parts by weight of filler and a fixing agent made of a cationic polymeric substance and an anionic polymeric substance, or a fixing agent made of a cationic polymeric substance and a nonionic polymeric substance are added. This process consists of dehydrating and paper-making an aqueous slurry for paper-making, which is made by using a cationic polymeric substance and an anionic polymeric substance in combination.
Alternatively, the filler can be efficiently fixed to the small-diameter inorganic fibers in the aqueous slurry by the action of a fixing agent using a combination of a cationic polymeric substance and a nonionic polymeric substance. Therefore, in the method of the present invention, a high-density inorganic fiber sheet that could not be obtained by conventional dehydration and papermaking methods is produced by the above-mentioned action in the aqueous slurry subjected to dewatering and papermaking. can get. [Example] Hereinafter, the specific structure of the method for producing an inorganic fiber sheet of the present invention will be explained using examples, and the physical properties of the obtained inorganic fiber sheet will be explained using the following example. This will be explained along with the physical properties. Example 1 10 parts by weight of small diameter glass fibers with an average fiber diameter of 0.7μ and a fiber length of 10 mm or less were dispersed in water, and the glass fiber concentration was
After obtaining a 0.05% by weight dispersion, 64 parts by weight of Cree powder having an average particle size of 2 μm as a filler was added, and the mixture was sufficiently stirred until there were no coarse particle agglomerates. Next, 90 parts by weight of E glass fibers having an average fiber diameter of 9 μm and a fiber length of 6 mm were added, and further, 18 parts by weight of fibrous polyvinyl alcohol as a binder component was added and stirred. After that, as a fixing agent, it is added as a solid component.
After adding 0.5 parts by weight of nonionic polyacrylamide, 0.5 parts by weight of cationic polyacrylamide (calculated as a solid component) was added to fully fix the filler, and the resulting aqueous slurry was hand-sheeted by a conventional method. An inorganic fiber sheet, which is the object product of the present invention, was obtained. Example 2 33 parts by weight of small glass fibers with an average fiber diameter of 0.7 μm and a fiber length of 10 mm or less were dispersed in water to reduce the glass fiber concentration.
After obtaining a 0.05% by weight dispersion, 200 parts by weight of magnesium hydroxide as a filler was added, and the mixture was sufficiently stirred until there were no coarse particle agglomerates. Next, 67 parts by weight of E glass fibers having an average fiber diameter of 9 μm and a fiber length of 6 mm were added, and further, 18 parts by weight of fibrous polyvinyl alcohol as a binder component was added and stirred. After that, as a fixing agent, it is added as a solid component.
After adding 0.5 parts by weight of nonionic polyacrylamide, 0.5 parts by weight of cationic polyacrylamide (calculated as solid components) was added to sufficiently fix the filler, and the resulting aqueous slurry was prepared in the same manner as in Example 1. The inorganic fiber sheet, which is the object product of the present invention, was obtained by hand-sheeting. Example 3 50 parts by weight of small diameter glass fibers with an average fiber diameter of 0.7μ and a fiber length of 10 mm or less were dispersed in water to reduce the glass fiber concentration.
After obtaining a 0.05% by weight dispersion, 80 parts by weight of aluminum oxide as a filler was added, and the mixture was sufficiently stirred until there were no coarse particle agglomerates. Next, 50 parts by weight of E glass fibers having an average fiber diameter of 9 μm and a fiber length of 6 mm were added, and further, 18 parts by weight of fibrous polyvinyl alcohol as a binder component was added and stirred. After that, as a fixing agent, it is added as a solid component.
After adding 0.5 parts by weight of nonionic polyacrylamide, 0.5 parts by weight of cationic polyacrylamide (calculated as solid components) was added to sufficiently fix the filler, and the resulting aqueous slurry was prepared in the same manner as in Example 1. The inorganic fiber sheet, which is the object product of the present invention, was obtained by hand-sheeting by the method described above. Example 4 In the procedure of Example 1, 300 parts by weight of clay powder was utilized as a filler, and as a fixing agent,
The same procedure as in Example 1 was followed except that after adding 0.5 parts by weight of cationic polyacrylamide in terms of solid components, 0.5 parts by weight of nonionic polyacrylamide in terms of solid components was added. An inorganic fiber sheet, which is the object product of the present invention, was obtained. Example 5 The same procedure as in Example 1 was followed except that 10 parts by weight of fine glass fibers with an average fiber diameter of 3 μm and a fiber length of 15 mm or less were used as the fine glass fibers, and the objective product of the present invention was obtained. An inorganic fiber sheet was obtained. Example 6 10 parts by weight of alumina-silica-based small-diameter ceramic fibers with an average fiber diameter of 3μ and a fiber length of 10mm or less were dispersed in water to obtain a dispersion with a ceramic fiber concentration of 0.05% by weight, and then clay with an average particle diameter of 2μ was dispersed in water. 64 parts by weight of powder was added and thoroughly stirred until there were no coarse particle agglomerates. Next, 90 parts by weight of ceramic fibers with an average fiber diameter of 10μ and a fiber length of 30mm or less were added, and the subsequent steps were as follows.
By carrying out the same formulation as the corresponding procedure of Example 1, an inorganic fiber sheet, which is the target product of the present invention, was obtained. Example 7 10 parts by weight of small diameter glass fibers with an average fiber diameter of 0.7μ and a fiber length of 10 mm or less were dispersed in water, and the glass fiber concentration was
After obtaining a 0.05% by weight dispersion, 64 parts by weight of clay powder with an average particle diameter of 2 μm was added as a filler, stirred thoroughly until there were no coarse particle agglomerates, and then E with an average fiber diameter of 9 μm and a fiber length of 6 mm was added. After adding 90 parts by weight of glass fiber, 0.5 parts by weight of nonionic polyacrylamide in terms of solid components and 0.5 parts by weight of cationic polyacrylamide in terms of solid components were further added as a fixing agent to form a filler. An aqueous slurry was prepared by thoroughly fixing. The obtained aqueous slurry of inorganic fibers was made into paper using a cylinder paper machine. In addition, an acrylic emulsion (Dow Chemical Company, DOW2647) with a concentration of 15% by weight was used in the paper machine.
is applied by a spray method at a ratio of 11% by weight calculated as a solid component based on the glass fiber component of a glass fiber sheet, and dried with a Yankee dryer to produce a continuously wound product of the present invention. An inorganic fiber sheet was obtained. Example 8 In the procedure of Example 1, 50 parts by weight of clay powder with an average particle size of 2μ was used instead of 64 parts by weight of clay powder with an average particle size of 2μ, and all other procedures were the same as in Example 1. An inorganic fiber sheet, which is the object product of the present invention, was obtained by formulating in the same manner as the corresponding procedure. Example 9 10 parts by weight of alumina-silica-based small-diameter ceramic fibers with an average fiber diameter of 3 μm and a fiber length of 10 mm or less were dispersed in water to obtain a dispersion with a ceramic fiber concentration of 0.05% by weight, followed by 300 parts by weight of magnesium hydroxide. was added and thoroughly stirred until there were no coarse particle lumps. Next, 90 parts by weight of ceramic fibers with an average fiber diameter of 10 μm and a fiber length of 30 mm or less were added, and 18 parts by weight of fibrous polyvinyl alcohol as a binder component was added.
parts by weight were added and stirred. After that, as a fixing agent, it is added as a solid component.
After adding 0.5 parts by weight of cationic polyacrylamide, 0.5 parts by weight of anionic polyacrylamide (calculated as a solid component) was added and sufficiently fixed, and the resulting aqueous slurry was subjected to manual papermaking by a conventional method. An inorganic fiber sheet, which is the object product of the present invention, was obtained. Example 10 10 parts by weight of small alumina fibers with an average fiber diameter of 1 μm and a fiber length of 10 mm or less were dispersed in water to obtain a dispersion liquid with an alumina fiber concentration of 0.05% by weight, and then 50 parts by weight of aluminum oxide as a filler was added. Then, 90 parts by weight of alumina fibers having an average fiber diameter of 10 μm and a fiber length of 6 mm were added and stirred. After that, as a fixing agent, it is added as a solid component.
0.5 parts by weight of cationic polyacrylamide was added, and 0.5 parts by weight of anionic polyacrylamide (calculated as a solid component) was added to fully fix the filler, and the resulting aqueous slurry was hand-sheeted by a conventional method. Then, an inorganic fiber sheet, which is the object product of the present invention, was obtained. Example 11 10 parts by weight of small glass fibers with an average fiber diameter of 0.7μ and a fiber length of 10mm or less were dispersed in water to obtain a dispersion with a glass fiber concentration of 0.05% by weight, followed by 300 parts of clay powder with an average particle diameter of 2μ. Parts by weight were added and stirred thoroughly until there were no coarse particle lumps. Next, 90 parts by weight of rock wool having an average fiber diameter of 10 μm was added, and further, 18 parts by weight of fibrous polyvinyl alcohol as a binder component was added and stirred. After that, as a fixing agent, it is added as a solid component.
After adding 0.5 parts by weight of nonionic polyacrylamide, 0.5 parts by weight of cationic polyacrylamide (calculated as a solid component) was added, and the resulting aqueous slurry was subjected to manual papermaking in a conventional manner.
An inorganic fiber sheet, which is the object product of the present invention, was obtained. Table 4 shows the composition of the papermaking components in each of the Examples above. Further, the physical properties of the obtained inorganic fiber sheet are shown in Table 5 together with the yield of filler. The basis weight of the inorganic fiber sheet is VIS P
8124, and the density is a value measured according to JIS P 8118. Furthermore, the filler yield is calculated by collecting the wire filtrate during paper making using a manual sheet machine for pulp testing as specified in JIS P 8209, filtering and drying, and then measuring the weight. The filler content was calculated based on the ash content and expressed as a ratio of the two.

【table】

【table】

【table】

[Table] Comparative Example 1 Using only E glass fibers with an average fiber diameter of 9μ and a fiber length of 6mm as the inorganic fibers in the aqueous slurry,
In addition, an inorganic fiber sheet for comparison was obtained in the same manner as in Example 1 except that 1% by weight of cationic polyacrylamide based on the glass fibers was used as a fixing agent. Comparative Example 2 All procedures were the same as those of Example 2, except that 1% by weight of cationic polyacrylamide based on glass fibers was utilized as the adhesion promoter.
An inorganic fiber sheet was obtained for comparison. Comparative Example 3 Using only E glass fibers with an average fiber diameter of 9μ and a fiber length of 6mm as the inorganic fibers in the aqueous slurry,
Further, an inorganic fiber sheet for comparison was obtained by omitting the addition of filler and fixing agent, and otherwise following the same procedure as in Example 1. Comparative Example 4 Using only E glass fibers with an average fiber diameter of 9μ and a fiber length of 6mm as the inorganic fibers in the aqueous slurry,
Omit the addition of fillers and fixatives; otherwise,
An inorganic fiber sheet for comparison was obtained by the same procedure as in Example 7. Comparative Example 5 The procedure of Example 1 was repeated except that 3 parts by weight of small diameter glass fibers and 97 parts by weight of E glass fibers were used.
An inorganic fiber sheet for comparison was obtained by the same procedure as in Example 1. Comparative Example 6 An inorganic fiber sheet for comparison was obtained in the same manner as in Example 1 except that 350 parts by weight of clay powder was used as a filler. Comparative Example 7 The procedure of Example 1 was repeated except that 40 parts by weight of clay powder was used as the filler.
An inorganic fiber sheet for comparison was obtained using the same procedure as described above. Comparative Example 8 Inorganic fibers for comparison were prepared in the same manner as in Example 1, except that glass fibers with an average fiber diameter of 5 μm and a fiber length of 10 mm were used as the small diameter glass fibers. Got a sheet. Table 6 shows the composition of the papermaking components in each of the examples above. Further, the physical properties of the obtained inorganic fiber sheet are shown in Table 7 together with the yield of filler.

【table】

【table】

〔Effect of the invention〕

The method of the present invention obtains an inorganic fiber sheet by a paper-making method, and it can obtain a high-density inorganic fiber sheet that could not be obtained by conventional paper-making methods. Compared to the manufacturing method of inorganic fiber sheets in which fillers are impregnated into existing inorganic fiber sheets, this method is far superior in terms of manufacturing equipment and energy consumption, and requires high density. An inorganic fiber sheet that can be used in the field, for example, as a face material for a composite type printed circuit board or a foamed resin board for heat insulation, can be efficiently obtained. In addition, the inorganic fiber sheet obtained by the method of the present invention can be obtained by impregnating the existing inorganic fiber sheet obtained in the previous step with a filler, or by using a slurry containing a large amount of filler. Compared to an inorganic fiber sheet made from a paper-made sheet, the filler is evenly distributed inside the sheet, so the physical properties of the inorganic fiber sheet are uniform and the quality is good.

Claims (1)

[Claims] 1 Small diameter inorganic fibers with an average fiber diameter of 3 μ or less 5
Inorganic fibers blended in a proportion of % by weight or more
50 to 300 parts by weight of filler per 100 parts by weight, and a fixing agent made of a cationic polymeric substance and an anionic polymeric substance, or a fixing agent made of a cationic polymeric substance and a nonionic polymeric substance. 1. A method for producing an inorganic fiber sheet, which comprises dewatering and paper-making an aqueous slurry to which is added.