JPS61239069A - Ceramic fiber blanket - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel ceramic fiber blanket, and more particularly to a blanket made of high alumina fibers.

Here, a blanket is a non-woven fabric product formed by intertwining fibers, and is different from plate-like processed products called boards and felts in that it does not substantially use a binder.

[Prior art]

Conventionally, commonly used alumina ceramic fibers are obtained by the so-called melt fiberization method, in which blended raw materials containing aluminum oxide, silicon oxide, etc. are melted and then fiberized. Although it is not impossible to use the fiber obtained from this process as it is, it is generally necessary to increase the bulk density of this fiber (for example, to a bulk density of around 0./fi/crA). density)
In order to make it an easy-to-handle material, it is used by needle-punching it to make blankets, or by dispersing it in water with an inorganic binder and then pressurizing and dehydrating it to make felts and boards.

Blanket manufacturing methods include stacking the fibers in layers and subjecting them to needle punching, as well as treating the fibers with a fiber treatment agent in advance, or adding a reinforcing nonwoven fabric between the layers. Improvement methods such as interposition are known.These improvement methods do not require high bulk, since the ceramic fiber itself is relatively hard, and if the needle punching treatment is performed as it is, the entanglement of the fibers will not be sufficiently prevented. This is done to increase density and strength.

Recently, high alumina ceramic fibers for high temperature use, especially fibers obtained by the so-called precursor fiberization method, have been attracting attention. This method is a method in which a fiber precursor solution of an aluminum compound, for example, a solution of aluminum oxychloride, is made into fibers and then fired to remove volatile components to obtain high alumina ceramic fibers.

However, the high alumina fibers obtained by such a precursor fiberization method are different from the fibers produced by the melt fiberization method, and when trying to make a blanket from the fibers as they are, the fibers cannot be entangled at all, and the fibers are not entangled. Even when treated with a treatment agent, the entanglement of the fibers is improved and the bulk density of the blanket is reduced to 0. /fi/7 or more cannot be achieved, and on the contrary, the use of fiber treatment agents increases costs.

Therefore, high alumina fibers are used as processed products such as felts and boards, but are not used as blankets (for example, "Fine Ceramics 'gii <Showa A; (Published by Fair Council, see page 1/co) [Problems to be solved by the invention] In view of the above circumstances, the present inventors have proposed a method for forming a blanket from high alumina fiber obtained by a precursor fiber forming method. As a result of intensive study, we broke away from the conventional technical common sense of processing fibers, which are the final products in the fiberization process, that is, fired fibers, and instead applied needle punching to fibers, tsuma υ, and unfired fibers before they become final products. We discovered that if the treatment is applied, the degree of entanglement that is equal to or greater than that obtained when a fiber treatment agent is applied, and that a good blanket can be obtained without causing any problems even after subsequent firing, has been developed. invention has been achieved.

The present invention was completed based on this unexpected finding, and its gist is that the ratio of aluminum to silicon is At20.
．． 99:l~qs:, 2g in terms of the ratio of and SjO□
A blanket made of alumina-siliceous fibers that does not contain a fiber treatment agent in the range of combined structure and 0. The present invention relates to a ceramic fiber blanket characterized by having a bulk density of ii/cut or more.

[Structure of the invention]

The blanket according to the present invention is manufactured by a precursor fiberization method with At20s:SiO□=q9:/~
7.2: Constructed with 2g of high alumina fiber.

The precursor fiberization method is a method in which an organometallic compound or a metal oxyhalide is fiberized in the presence or absence of a suitable organic thickener, and then volatile parts or volatile components are removed by firing.

In the production of the blanket according to the present invention, unfired alumina-based fibers obtained by fiberizing a spinning dope containing aluminum oxychloride and a silicon compound are usually used. The blanket according to the present invention can be produced by stacking the unfired fibers in layers, needle punching them to form an unfired blanket, and then firing this.

A method for producing an aluminum oxychloride solution is known, and can be produced, for example, by dissolving metallic aluminum in hydrochloric acid or an aqueous aluminum chloride solution. The atomic ratio of At10t in aluminum oxychloride is usually 0 to 1, preferably 86 to 1. It is 9. If this ratio is too small, it will be difficult to obtain a solution with an appropriate aluminum concentration as a spinning dope, and if this ratio is too large, the solution will become unstable and there is a risk that aluminum hydroxide gel will precipitate. There is.

As the silicon compound, silica sol is preferred, but water-soluble silicon compounds such as tetraethyl silicate and water-soluble siloxane derivatives can also be used. These silicon compounds also change to silica during the firing process of the precursor fibers, and alumina becomes α-
It has the effect of suppressing alumina formation and suppressing alumina crystal growth.

The ratio of aluminum oxychloride to silicon compound in the spinning dope is A 1.0. Converting to the ratio of s 1 o2, 9
The range is 9:1 to 722:g. If the amount of silicon compound is even less than this range, the alumina that makes up the fibers will be
- The alumina is hard to form, and the alumina particles become coarse and the fibers become brittle.

Conversely, if the amount of silicon compounds is too large,
In addition to A1□O1φ, 2S102), silica (S10□)
is formed, resulting in a significant decrease in heat resistance.

It is preferable that an organic polymer be present in the spinning dope. A spinning stock solution obtained by adding a silicon compound to an aqueous aluminum oxychloride solution and concentrating it to a predetermined concentration can also be used, but the presence of an organic polymer in the spinning stock solution improves spinnability. Examples of organic polymers include various natural or synthetic polymeric compounds capable of forming fibers, such as soluble derivatives of starch and cellulose such as acetated starch, hydroxyethyl starch, methylcellulose, and carboxymethylcellulose, polyvinyl alcohol, polyethylene glycol, and polyethylene glycol. Water-soluble synthetic polymer compounds such as acrylamide are used. In addition, when selecting the organic polymer, care must be taken to ensure that the spinning dope does not become cloudy or precipitate. The organic polymer is added to the spinning dope so that it has an optimum viscosity for the spinning method applied, but usually it may be added so that the viscosity of the spinning dope becomes 1 to 1000 voids.

The spinning dope is prepared by adding a silicon compound and an organic polymer to an aqueous aluminum oxychloride solution and concentrating the solution to a predetermined aluminum concentration. If desired, the silicon compound and organic polymer may be added to the solution during or after concentration. In particular, organic polymers may cause foaming during concentration, and in such cases it is preferable to add the organic polymer after concentration.

As the spinning method, any known method such as an extrusion method, a stretching method, a blowing method, a centrifugation method, etc. can be adopted. For example, in the case of the blowing method, the spinning stock solution adjusted to a poise of 0~ioo is added to 0, / -0,! ; Spinning is carried out by extrusion into a high-speed air stream through the pores of tranφ. The extruded spinning dope is drawn in an air flow at a temperature of 200° C. or lower, preferably 0 to 100° C., and dried to obtain a precursor fiber. This method requires that the precursor fibers be sufficiently dried before being collected from the air stream. If drying is insufficient, the collected precursor fibers may adhere to each other or become droplets due to elastic recovery, resulting in shots.

Therefore, if necessary, heated air may be used to promote evaporation of the solvent within a range that does not cause foaming.

On the other hand, if the drying is too strong, the precursor fibers may not be fully drawn, the fiber diameter may become too thick, or the H2 in the precursor fibers may become too thick.
Since the O content, aZ content, organic polymer, etc. are volatilized beyond thermal decomposition, the l fibers lack flexibility and become unsuitable for the needle punching treatment described below. That is, the blanket according to the present invention is manufactured through a process of needle punching unfired fibers, but this is because the precursor fibers are soft in nature when they are organic metal compounds or metal oxyhalides. The purpose is to perform the needle punching process by taking advantage of certain factors, and therefore, if thermal decomposition occurs as described above, it is not suitable for the intended purpose.

Also, from this point of view, it is preferable to use a spinning dope containing an organic thickener such as polyvinyl alcohol.

The unfired precursor fibers are amorphous and highly flexible, so by accumulating them in layers in this state and then applying a needle punching treatment, most of the fibers are not cut. They can be intertwined with each other. By appropriately selecting the number of needle punching from the range of 1 to 30 times/7, a blanket with a desired bulk density can be obtained. Needle punching is 5-1 to get a blanket
It is preferable to carry out 0 times/d. The blanket consisting of the green body of fibers thus obtained is then heated to 500°C.
By firing at the above-mentioned high temperature, even after the organic polymer is burned out, the intertwining between the fibers can be maintained as is, and an alumina fiber blanket having the desired bulk density and tensile strength can be obtained. Follow the usual method for baking! The temperature is preferably 200-1300°C. At temperatures below SOO°C, the alumina fibers of the resulting blanket have low strength, are brittle, and have a large reheating shrinkage rate at 110°C, making them unsuitable for practical use. Moreover, when heated to 71,700° C. or higher, grain growth of crystals progresses, and the strength of the resulting fiber decreases.

In the blanket according to the present invention, most of the fibers are arranged substantially parallel to the flat plane of the blanket, and the fibers extending from the surface (flat plane) inward are intertwined with this, θ,
The bulk density and mechanical strength of the blanket are greater than /i/cnt.

Furthermore, since the blanket is made of fibers that do not contain fiber treatment agents or other organic substances, it does not generate harmful gases even when exposed to high temperatures.

Furthermore, since the blanket according to the present invention is composed of high alumina-based alumina-siliceous fibers, it has better heat resistance than blankets made of ceramic fibers obtained by melting fibers, and is useful for fireproof materials, etc. It is.

The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 Aluminum oxychloride aqueous solution (aluminum content = oy7t, ht7'at (atomic ratio) = /, g) l
27 g 1 liter of a 351.5% coQ% silica sol solution in polyvinyl alcohol aqueous solution was added to the mixture and mixed. This mixed solution was concentrated at 50°C under reduced pressure to form a spinning dope (viscosity: 27
Poise, alumina content 2 /,,! wt%),
Raw fibers were obtained by spinning using a blowing method. The approximate bulk density of this material was 77 o, ozg. This is collected into layers and needle punching machine (needle spacing 15 to 2.3
A blanket was obtained by punching 6 to 7 times/7 using a 2.2-part needle). Then this /21
, 0°C for 1 hour in air. This blanket has a bulk density o, lo y /at! , H pulling strength box kg
/ d.

Comparative Example 1 The raw fiber obtained by the method of Example 1 was fired in air at 1 sto°C for 1 hour to obtain alumina fiber.

Thereafter, the cotton was collected in the same manner as in Example 1 and subjected to needle punching treatment to obtain a blanket. This blanket has a bulk density of 0.0! ; /i /Crt! , tensile strength o,
bkg/a/l.

Comparative Example The raw fibers obtained by the method of Example 1 were fired in air at 1-60°C for 1 hour to obtain alumina fibers.

This was impregnated with a fiber treatment agent consisting of a water emulsion of 1,200 parts of H, 01,200 parts of kerosene, and 1 part of fatty acid amine acetate, subjected to the same needle punching treatment as in Example 1, and then dried to obtain a blanket. This blanket has a bulk density of 0.09 g/cIIt1 and a tensile strength of 80 kg.
/ at! Met.

Claims (2)

[Claims] (1) The ratio of aluminum and silicon is Al_2O_3 and S
A blanket made of alumina-siliceous fibers that do not contain a fiber treatment agent and have a ratio of iO_2 in the range of 99:1 to 72:28, the alumina-siliceous fibers being accumulated parallel to the flat plane. A ceramic fiber blanket characterized by having a structure in which the fibers are intertwined with each other from the flat plane of the blanket toward the inside, and a bulk density of 0.1 g/cm^3 or more. (2) The fibers directed inward from the flat plane of the blanket are oriented inward from the flat plane by needle punching the fibers accumulated parallel to the flat plane. A ceramic fiber blanket according to claim 1.