JPH03124865A - Binder for heat-resistant fiber nonwoven fabric, heat-resistant fiber nonwoven fabric and its production - Google Patents

Abstract

PURPOSE:To obtain the subject binder, composed of a hydrolyzate condensate of methyltrimethoxylilane, etc., with an acid and water, capable of withstanding high temperatures and intense heat, having flexibility without deteriorating strength and suitable for uses, such as electrical insulation. CONSTITUTION:The objective binder which is a hydrolyzate condensate composed of one or a mixture of two or more selected from methyl(or ethyl) trimethoxysilane and methyl(or ethyl)triethoxysilane, and acid and water. Furthermore, a heat-resistant fiber nonwoven fabric is preferably coated or impregnated with the aforementioned binder without aging to afford a heat-resistant fiber nonwoven fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-resistant fibrous nonwoven fabric that has excellent heat resistance, water resistance, chemical resistance, electrical insulation, flexibility, etc., and is easy to manufacture.

(Prior art) Various types of non-i-fibers represented by glass fibers and ceramic fibers, and various high-performance organic fibers represented by aromatic polyamide (aramid) fibers, etc. IN has heat resistance, nonflammability, heat insulation, electrical insulation, chemical stability, abrasion resistance, and strength 1!1
Since it has many excellent characteristics such as high elastic modulus, attempts have been made to make use of these characteristics to make it into a nonwoven fabric.

In particular, when making a nonwoven fabric with emphasis on heat resistance, heat-resistant lIH does not have self-adhesive strength in most cases, so adhesives are used to bond the fibers.

Conventionally, attempts have been made to use cellulose or organic adhesives, alumina sol, colloidal silica, inorganic substances such as asbestos, or a combination of both to form non-woven fabrics. However, each of these adhesives has its own drawbacks, and at present no sheet is commercially available that takes full advantage of its heat-resistant 18H characteristics. In other words, non-woven fabrics made using cellulose bulbs or organic adhesives as binders have the disadvantage that the organic matter decomposes at high temperatures of 200°C or higher, resulting in extremely weakened strength, collapse, and inability to maintain shape. there were. In addition, non-woven fabrics using alumina sol, colloidal silica, etc. as binders have V! The strength of the non-woven fabric is insufficient because it is inferior to I-wear and cracks easily at high temperatures.In order to increase the strength of the sheet, increasing the amount of binder results in a lack of flexibility, and its range of applications is limited. The problem was that it was extremely narrow. On the other hand, asbestos has the disadvantage that its carcinogenicity is a problem and its use is being restricted.

In addition, recent research by the present inventors has revealed that JP-A-64-77
No. 000 and Japanese Patent Application No. 63-67141 proposed that a hydrolyzed condensate of an alkyl silicate ester is effective as a heat-resistant mM inter-IIN binder.

However, since these binders use wired solvents such as alcohols as solvents, it is difficult to use them in ordinary paper machines from the viewpoint of safety.

Furthermore, JP-A No. 64-85369 discloses an aqueous binder containing rod-shaped colloids, trialkoxysilane, acid, and water, but this aqueous binder requires a complicated preparation process because it contains rod-shaped colloids. In addition, due to the aging process, the hydrolysis reaction progresses, resulting in a shortened pot life.

(Problems to be Solved by the Invention) As described above, although various heat-resistant fibers have excellent heat resistance, due to the lack of suitable binders, the heat resistance of the fibers cannot be fully utilized. It has been difficult to easily produce nonwoven fabrics that have

An object of the present invention is to solve the above-mentioned problems and provide a heat-resistant fiber nonwoven fabric that takes advantage of the characteristics of heat-resistant m-fibers.

In particular, materials that can withstand high temperatures and high heat conditions, which have recently been demanded from various quarters, as well as have thermal insulation properties, adsorption properties, sinterability, strength, abrasion resistance,
The purpose of the present invention is to provide a heat-resistant fibrous nonwoven fabric suitable for applications requiring properties such as electrical insulation.

(Means for solving the vR problem) In view of the above circumstances, the present inventors have conducted intensive studies and found that methyl By using an aqueous solution of a hydrolyzed condensate of trimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, or ethyltriethoxysilane, the hot strength at high temperatures hardly deteriorates and the shape is maintained.
The inventors discovered that since there is no coloration due to thermal decomposition and it is an aqueous solution, it can be easily used in ordinary paper machines, and based on this knowledge, the present invention was completed.

That is, the present invention is a hydrolyzed condensate consisting of one or a mixture of two or more selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane, an acid, and water. It is a binder for heat-resistant fibrous nonwoven fabrics.

Further, the present invention provides a heat-resistant fiber having a length of 1 mm selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane.
This is a heat-resistant mm nonwoven fabric characterized by being bonded with a hydrolyzed condensate binder consisting of seeds, acids, and water.

Further, the present invention is obtained by adding one or more mixtures selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane to water containing an acid and dissolving the mixture. This is a method for producing a heat-resistant fibrous non-woven fabric, which comprises coating or impregnating a hydrolyzed condensate as a binder on the heat-resistant fibrous non-woven fabric without aging.

Next, the formation and preparation method of the binder composition of the present invention will be explained.

(1) Structure of binder composition (a) One type or a mixture of two or more types selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane can be used. The properties required as a binder for nonwoven fabrics include forming a strong film without cracks at the intersections of lIH. Focusing on this point, we investigated the film-forming properties and adhesion to substrates of various dialkoxysilanes, trialkoxysilanes, and tetraalkoxysilane hydrolyzed condensates, and found that most of them were similar to ordinary inorganic materials. However, only the hydrolyzed condensates of the four types of trialkoxysilanes exhibited excellent film-forming properties and adhesion.

Furthermore, it was confirmed that the four types of trialkoxysilanes have superior tensile strength at room temperature and after heating, compared to other alkoxysilanes.

(b) Acids Examples of acids used in the present invention include inorganic acids such as nitric acid and hydrochloric acid, acetic acid, formic acid, propionic acid, maleic acid, chloroacetic acid, citric acid, benzoic acid, dimedylmalonic acid, glutaric acid, glycolic acid, and malonic acid. I1M acids such as toluenesulfonic acid and oxalic acid can be mentioned.

The proportion of such acid in the binder composition is preferably 0.01 to 3 parts by weight; less than 0.01 part by weight will result in insufficient hydrolysis of the alkoxysilane, while if it exceeds the triple bend, the binding will be impaired. The agent composition becomes easier to gel.

(C) Water The proportion of water in the binder composition used in the present invention is at least the minimum amount of water required for complete hydrolysis of trialkoxysilane, which is calculated from the reaction formula for complete hydrolysis of trialkoxysilane. use

For example, 0.4 for 1 g of methyltrimethoxysilane
Use 0.3 g or more of water per 1 g of methyltriethoxysilane.

(2) Preparation method of binder The binder of the present invention is prepared by combining (a) methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane or ethyltriethoxysilane or a mixture thereof (b) acid and (C) water. V4 can be produced by mixing and hydrolyzing while making a uniform dispersion by high-speed stirring or the like. Methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane or 1
Deltriethoxysilane undergoes a hydrolysis reaction and a polycondensation reaction in the presence of an acid catalyst to produce a polysiloxane compound, which is cured at room temperature or by heating and acts as a binder. Normally, alkoxysilane hydrolysis is carried out in an organic solvent such as alcohol, which is a common solvent for both alkoxysilane and water, in order to uniformly mix the two, but in the present invention, a common solvent is not used, and the hydrolysis is performed at high speed. It is characterized by obtaining a uniform aqueous solution by stirring or the like. For this reason, the binder according to the invention has a low TiR solvent content and can be used perfectly, especially in paper machines without explosion protection equipment. Note that this binder is unstable and easily gels, so it is desirable to use it immediately after preparation.Additionally, various fillers with particle sizes up to several tens of microns may be added to the binder of the present invention as necessary. There is absolutely no harm in adding it.

On the other hand, the heat-resistant fiber used in the present invention is selected depending on the heat resistance and characteristics required of the nonwoven fabric, and its type is not particularly limited. For example, silica fiber (quartz 1JA fiber),
High silicate TL! miscellaneous, glassy silica fibers, ceramic fibers H (alumina/silica vaIft>, aluminum + mm, kaolin fibers, bauxite fibers, zirconia! IN, potassium butanoate fibers, quartz carbide whiskers, metal fibers, carbon fibers, glass fibers, Aromatic polyamide (aramid) Illi cloth and the like can be used.

The heat-resistant fibrous nonwoven fabric of the present invention is produced by the following method. That is, a dispersion slurry in which various heat-resistant fibers are dispersed in water by an appropriate method is obtained by a wet paper making method or a method similar thereto, and methyltrimethoxysilane, methyltriethoxysilane,
The heat-resistant 11 fiber nonwoven fabric of the present invention can be obtained by applying or impregnating an aqueous solution of a hydrolyzed condensate of ethyltrimethoxysilane or ethyltriethoxysilane, and then performing a drying process at 100 to 200°C.

The process of applying or impregnating an aqueous solution of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, or a hydrolyzed condensate of ethyltriethoxysilane or a mixture thereof can achieve the strength and heat resistance required for heat-resistant tag nonwoven fabrics. Although it can vary depending on gender,
Usually, about 5 to 30% by weight based on the weight of the nonwoven fabric is sufficient. If the amount of adhesion is less than 5% by weight, the strength of the nonwoven fabric will be insufficient, and if it exceeds 30% by weight, the nonwoven fabric will lose its flexibility and become prone to breakage.

The heat-resistant mM nonwoven fabric of the present invention can be manufactured into sheets of various thicknesses, but the present invention is characterized by the fact that it can produce a relatively thin nonwoven fabric, with a basis weight of 30 to 500 g/rI.
11 preferably 50 to 3009/7d.

The heat-resistant fiber nonwoven fabric of the present invention uses heat-resistant fibers, and
Since the NN viscous binder is an aqueous solution of a hydrolyzed condensate of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, or ethyltriethoxysilane, or a mixture thereof, it has excellent properties while maintaining flexibility. Excellent heat resistance, water resistance, chemical resistance, electrical insulation, etc. The reason for this effect is not clear, but methyltrimethoxysilane, methyltriethoxysilane,
The polysiloxane compound in the aqueous solution of the hydrolyzed condensate of ethyltrimethoxysilane or ethyltriethoxysilane or a mixture thereof is further polymerized by heat treatment,
This seems to be because the bonding points between the heat-resistant fibers are tightly coated with a dense silica film that has excellent heat resistance and chemical resistance. As for the heat treatment conditions at this time, a dense film can be obtained at a relatively low temperature of about 200° C. or less, and there is no need to bake at a particularly high temperature.

(Actual Flow Example) Examples of the present invention will be specifically described below. All percentages (%) in the explanation are weight percentages.

Reference Example 1 5 g of acetic acid was added to 4495 g of distilled water, and while stirring at high speed, soo g of methyltrimethoxysilane was gradually added and completely dissolved, resulting in hydrolytic condensation of methyltrimethoxysilane with a solid content of approximately 5%. An aqueous solution was obtained. This aqueous solution was immediately used as a binder. In addition, in order to investigate the impact of aging on the pot life of this aqueous solution, we maintained the temperature of this aqueous solution at 50°C immediately after preparation and aged it for 1 hour, and precipitation occurred in 3 days. Ta. If the aqueous solution is not aged, precipitation will occur in 9 days, so aging of the aqueous solution is not preferred from the viewpoint of pot life.

Reference Example 2 The same procedure as in Reference Example 1 was carried out except that methyltriethoxysilane was used instead of methyltrimethoxysilane to obtain an aqueous solution with a solid content of about 4%.

Reference Example 3 The same procedure as in Reference Example 1 was carried out except that ethyltrimethoxysilane was used instead of methyltrimethoxysilane to obtain an aqueous solution with a solid content of approximately 5%.

Reference Example 4 The same procedure as in Reference Example 1 was carried out except that ethyltriethoxysilane was used in place of methyltrimethoxysilane to obtain an aqueous solution with a solid content of approximately 4%.

Reference Example 5 Add 5 g of acetic acid to distilled water of 44959, gradually add 250 g of methyltrimethoxysilane while stirring at high speed, then gradually add 250 g of methyltriethoxysilane to completely dissolve it, An aqueous solution of a mixed hydrolyzed condensate of methyltri, methoxysilane and methyltriethoxysilane with a solid content of about 4.5% was obtained.

Reference Example 6 In Reference Example 5, ethyltrimethoxysilane was used instead of methyltrimethoxysilane, and ethyltriethoxysilane was used instead of methyltriethoxysilane, and 1-methyltrimethoxysilane and ethyltriethoxysilane with a solid content of 465% were obtained. The same procedure as in Reference Example 5 was carried out except that an aqueous solution of the mixed hydrolyzed condensate was obtained.

Example 1 To the pulper of Yongwin3! ! As a miscellaneous dispersant, polyethylene oxide (manufactured by Tetsu Seikagaku ■, PE0-18) was used at a concentration of 0.
．． Dissolve in water to a concentration of 2%, then add 2g of glass fiber (manufactured by Asahi Fiberglass, C3O6JA-861Δ).
A glass fiber dispersion was prepared by dispersing the fibers to a concentration of 1/1. Using this glass fiber dispersion, a glass fiber wet web was made into paper using an inclined wire mesh type nonwoven fabric manufacturing test machine.

Next, the glass fiber sheet was impregnated with the hydrolyzed condensate of methyltrimethoxysilane obtained in Reference Example 1 to a concentration of 10%, and dried at 150°C for 1 minute to give a basis weight of 100g/button. A glass fiber nonwoven fabric was obtained.

Example 2 One ceramic fiber H (aluminum psi fiber, made by Nippon Steel Chemical Co., Ltd., S C-1260) was added to a pulper with a capacity of 1 t 1 m3.
A ceramic fiber slurry was prepared by dispersing the fibers to a concentration of 0 g/j. This slurry gradually overflows from the outlet at the top of the pulper and is guided onto a 30-mesh wire mesh.
The shot was removed at the same time as the ceramic IE, H was collected. Ceramic fiber N5K subjected to such treatment
y was put into 1 TrL3 of water and sufficiently stirred to disperse it.

Using this ceramic II miscellaneous dispersion liquid, a ceramic mm wet web was made into paper using a tilted wire mesh type nonwoven fabric manufacturing test machine.

Next, 10% of the hydrolyzed composite of methyltrimethoxysilane obtained in Reference Example 1 was added to the ceramic m-thread sheet.
After drying at 150°C for 1 minute, a ceramic fiber nonwoven fabric with a basis weight of 100 g/m was obtained.

Example 3 Alumina 1IN (manufactured by Denki Kagaku Kogyo ■, Denka Alsen Bulk) was dispersed in a pulper having a volume of ff11m3 to a concentration of 2 g/l to obtain an alumina 8M dispersion.

Using this alumina M fiber dispersion liquid, wet alumina fiber "QUEB" paper was made in the same manner as in Example 1, and the hydrolyzed condensate of methyltriethoxysilane obtained in Reference Example 2 was applied to the aluminum TM fiber sheet. It was impregnated to a concentration of 10%, and dried at 150℃ for 1 minute.
An alumina fiber nonwoven fabric of 0.07/m was obtained.

Example 4 In Example 1, aromatic polyamide (aramid) fiber N (manufactured by DuPont, Kevlar 49.2d) was used as the heat-resistant fiber.
In the same manner as in Example 1, except that the hydrolyzate of methyltriethoxysilane obtained in Reference Example 2 was used as the binder, tsubo fn1
00g/Td aromatic polyamide fiber nonwoven fabric was obtained.

Example 5 In Example 1, carbon fiber (Besphite HTAC-6, manufactured by Toho Rayon ■) was used as the heat-resistant fiber, and methyltrimethoxysilane and methyltriethoxysilane obtained in Reference Example 5 were used as the binder. 100 g of tsubo fd was prepared in the same manner as in Example 1 except that the mixed hydrolysis condensate was used.
/A charcoal x mm nonwoven fabric was obtained.

Example 6 Same as Example 1 except that the hydrolyzed condensate of ethyltrimethoxysilane obtained in Reference Example 3 was used instead of the hydrolyzed condensate of methyltrimethoxysilane as the binder. A glass fiber nonwoven fabric with a tsubo J of 1100 g/m was obtained in the same manner.

Example 7 Same as Example 2 except that the hydrolyzed condensate of ethyltrimethoxysilane obtained in Reference Example 3 was used instead of the hydrolyzed condensate of methyltrimethoxysilane as the binder. A ceramic fiber nonwoven fabric with a weight of 1,100 g/bottom was obtained in the same manner.

Example 8 Example 3 except that instead of using the hydrolyzed condensate of methyltriethoxysilane as the binder in Example 3, the hydrolyzed condensate of nibbletriethoxysilane obtained in Reference Example 4 was used. An alumina fiber nonwoven fabric having a tsubo of 1100 g/m was obtained in the same manner as above.

Example 9 Same as Example 4 except that instead of using the hydrolyzed condensate of methyltriethoxysilane as the binder, the hydrolyzed condensate of ethyltriethoxysilane obtained in Reference Example 4 was used. An aromatic polyamide 11 fiber nonwoven fabric having a basis weight of 1009/m was obtained in a similar manner.

Example 10 In Example 5, instead of using the mixed hydrolyzed condensate of methyltrimethoxysilane and methyltriethoxysilane as the binder, a mixed hydrolyzed condensate of ethyltrimethoxysilane and ethyltriethoxysilane obtained in Reference Example 6 was used. The basis weight was 100 in the same manner as in Example 5 except that the decomposition condensate was used.
A carbon fiber nonwoven fabric having a weight of 1.5 g/g was obtained.

Reference Example 7 In Reference Example 1, n-70 pyltrimethoxysilane was used instead of methyltrimethoxysilane, and solid
It was used as a binder in exactly the same manner as in Reference Example 1, except that a % aqueous solution was obtained.

Reference Example 8 In Reference Example 1, instead of methyltrimethoxysilane,
Using phenyltrimethoxysilane, solid approximation 6,5
It was used as a binder in exactly the same manner as in Reference Example 1, except that a % aqueous solution was obtained.

Reference Example 9 Used as a binder in the same manner as in Reference Example 1 except that 3-aminopropyltriethoxysilane was used instead of methyltrimethoxysilane and an aqueous solution with a solid content of approximately 5% was obtained. did.

Reference Example 10 In Reference Example 1, instead of methyltrimethoxysilane,
Tetramethoxysilane was used as a binder in exactly the same manner as in Reference Example 1, except that an aqueous solution containing about 1% solids was obtained.

Comparative Example 1 The same procedure was carried out as in Example 1 except that the hydrolyzed composite of n-propyltrimethoxysilane obtained in Reference Example 7 was used instead of the hydrolyzed composite of methyltrimethoxysilane as the binder. 10 to 11 tsubo in the same way as Example 1
0g7. (Glass fiber nonwoven fabric was obtained.

Comparative Example 2 Example 2 except that instead of using the hydrolyzed condensate of methyltrimethoxysilane as the binder, a hydrolyzed condensate of phenyltrimethoxysilane, which was blued in Participant Example 8, was used. A ceramic I miscellaneous nonwoven fabric of Tsubo Gloog/Go was obtained in the same manner as described above.

Comparative Example 3 Example except that instead of using the hydrolyzed condensate of methyltrimethoxysilane as the binder in Example 1, the hydrolyzed condensate of 3-aminopropyltriethoxysilane obtained in Reference Example 9 was used. Basis weight 100 using the same method as 1.
A glass fiber nonwoven fabric of g/m was obtained.

Comparative Example 4 Same as Example 2 except that instead of using the hydrolyzed condensate of methyltrimethoxysilane as the binder in Example 2, the hydrolyzed condensate of tetramethoxysilane obtained in Reference Example 10 was used. A ceramic fiber nonwoven fabric having a tsubo M of 100 SF/Td was obtained by this method.

Comparative Example 5 The same method as in Example 1 except that an acrylic resin emulsion (manufactured by Dainippon Ink (II), Boncourt 5FC55) was used instead of the hydrolyzed condensate of methyltrimethoxysilane as the binder in Example 1. detsuboffl 10
A glass amuts cloth of 0 (J/rrl) was obtained.

Comparative Example 6 The same method as in Example 2 was used except that alumina sol (manufactured by Nissan Chemical Industries, Ltd., Alumina Sol 200) was used instead of the aqueous solution of hydrolyzed condensate of methyltrimethoxysilane as the binder. Tsuboffl 100g/Td
A ceramic fiber nonwoven fabric was obtained.

The table shows the tensile strength at room temperature, the tensile strength when heated at each temperature, and the appearance shape retention of the various heat-resistant fibrous nonwoven fabrics produced in this way.

From the results shown in the table, the strength of the heat-resistant fibrous nonwoven fabric of the present invention hardly decreases even after heat treatment, whereas the alkoxysilanes other than the claims of the present invention in Comparative Examples 1 and 2.3.4 The nonwoven fabric using the organic emulsion adhesive of Comparative Example 5 has low strength at room temperature and after heating, making it unusable, and the nonwoven fabric using the organic emulsion adhesive of Comparative Example 5 almost loses its strength after heating, and the inorganic emulsion adhesive of Comparative Example 6 Nonwoven fabrics using alumina sol have weak strength and are not practical, regardless of whether they are heat-treated or not.

(Effects of the Invention) As explained above, the heat-resistant AIM nonwoven fabric of the present invention can withstand high heat when placed above hot water, and its strength hardly decreases.
In addition, it has unprecedented properties such as flexibility and ease of processing, as well as electrical insulation, water resistance, chemical resistance, and
It also has wear resistance. For this reason, its uses include heat-resistant filter materials, catalyst carriers, heat exchange elements, separators, laminated plate materials, far-infrared radiation elements, R-ray coating materials, heat-resistant/fire-resistant papers, and heat-resistant insulation materials for the electronics industry (e.g., ceramic printed circuit board bases). Heat-resistant backing materials (for materials, etc.), wear-resistant monthly materials (for example, automobile brakes, clutches, etc.), noncombustible building materials mH
It can be used in a wide range of applications, such as base materials for reinforced ceramics and underlays for ceramic firing, and is extremely useful in these fields.

Claims (3)

[Claims] 1. A heat-resistant fiber characterized by being a hydrolyzed condensate of one or more mixtures selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane, acid, and water. Binding agent for non-woven fabrics. 2. Methyltrimethoxysilane between the fibers of heat-resistant fibers,
A heat-resistant fiber characterized by being formed by bonding one or more mixtures selected from methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane with a hydrolyzed condensate binder consisting of acid and water. Non-woven fabric. 3. A hydrolyzed condensate obtained by adding one type or a mixture of two or more types selected from methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane to water containing an acid and dissolving it. ,
A method for producing a heat-resistant fibrous non-woven fabric, which comprises coating or impregnating the heat-resistant fibrous non-woven fabric as a binder without aging.