JPH0441757A - Production of blanket made of alumina fiber - 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] [Industrial application field] The present invention relates to a method for producing .

[Conventional technology]

One of the refractory insulation materials used in high-temperature furnaces and the like is a blanket made of inorganic fibers, but it is not easy to manufacture ceramic fibers, which have good heat resistance among inorganic fibers. This is because ceramic fibers are generally rigid and do not easily cause entanglement, and when attempting to cause entanglement through needle punching, they become brittle and break easily! It's rice. Crystalline alumina fibers have particularly remarkable properties such as these, and it is difficult to utilize their excellent heat resistance in the form of a blanket.

One of the means to solve the above-mentioned problems is Japanese Patent Application Laid-open No. 60881.
No. 62 discloses that a layered accumulation of still flexible unfired fibers obtained by a precursor fiberization method is subjected to a needle punching treatment, and then,
Firing takes place. However, although unfired precursor fibers are flexible, they have low strength and are easily broken by needle punching, so that the effect of needle punching tends to be insufficient in terms of the final product.

In addition, since unfired precursor fibers are not water resistant, the lubricant that is attached to the fibers to reduce the coefficient of friction when needle punching a blanket-like aggregate of precursor fibers must be non-aqueous. Not (Unexamined Japanese Patent Publication No. 1986-
17060). However, nonaqueous lubricants require special processing equipment, and the lubricants themselves are expensive.

[Problem to be solved by the invention]

Therefore, the purpose of the present invention is to make it possible to use a water-based antifriction agent that is easy to handle, to ensure the effect of needle punch treatment, and to improve the alumina fiber blanket that is resistant to delamination and has excellent physical properties. The objective is to provide a method that can be manufactured efficiently.

[Failure to solve the problem]

The blanket production method of the present invention, which has succeeded in achieving the above object, produces a fleece of alumina fiber precursor fibers by spinning a fiber-forming solution of an aluminum compound, collecting the fibers into a fleece shape, and drying the fibers. The fleece of the precursor fibers is fired at a low temperature, a water-based anti-friction agent is attached to the fired fleece, and the fleece is then laminated to the thickness required for blanket production in the above or any other process. The method is characterized in that the lubricant-treated fleece laminate is needle-punched and then fired at a high temperature until crystalline alumina fibers are produced from the low-temperature fired fibers.

This manufacturing method was completed based on the following new findings by the present inventors. In other words, if a step of firing the precursor fibers to produce crystalline alumina fibers is performed at a relatively low temperature, the resulting fibers will already have sufficient water resistance; It is much stronger than body fibers, and more flexible than that produced by high-temperature firing to fully form crystalline alumina. Due to its water resistance, water-based lubricants can be used as anti-friction agents, so many methods such as the so-called dipping method can be used to attach them to the fibers, making it easy to apply the anti-friction agents uniformly. can. As described above, the low-temperature fired fiber has properties that are extremely suitable for needle punching.

When producing an alumina fiber blanket by the production method of the present invention, the step of producing precursor fibers from a solution of an aluminum compound can be carried out by any method with reference to well-known methods. Usually, preferred raw material aluminum compounds include aluminum oxychloride, basic aluminum acetate, and basic aluminum lactate. As a silica source to be added in a small amount to this, Nricazol, tetraethyl silicate, etc. are suitable.

Examples of organic polymers added to impart fiber-forming properties to the aluminum compound solution include polyvinyl alcohol,
Polyethylene glycol, polyacrylamide, etc. can be used. A solution of the above-mentioned raw materials is concentrated to prepare a spinning solution having a viscosity of about 1 to 500 poise, and it is made into fibers by a spinning method such as a centrifugal method or a blowing method.

The formed precursor fibers are received by a conveyor running directly below the spinning device, resulting in a fleece or thin sheet-like collection of precursor fibers. After drying, it is fired in an oxidizing atmosphere to decompose the organic matter and aluminum compound in the precursor fiber. This calcination is important because calcination in the normal alumina fiber manufacturing process can yield crystalline alumina.
Whereas the process is carried out at around 00°C, it is carried out at a lower temperature, preferably about 400°C to 800°C, in such a way that substantially no crystalline alumina is formed.

An oil agent and an anti-friction agent are applied to the resulting low-temperature fired fleece to reduce the coefficient of friction between the needle and the fibers during needle punching. The amount of the anti-friction agent deposited is approximately 0.5 to 5% by weight as solids based on the low-temperature fired fleece. Since the precursor fiber is a water-resistant low-temperature fired fiber, an emulsion obtained by emulsifying higher alcohol, paraffin mineral oil, etc. in water with various surfactants can be used as the anti-friction agent. The treatment can also be carried out by any method, such as spraying the fleece with an anti-friction agent or immersing the fleece in a diluted anti-friction solution.

The anti-friction treated fleece is stacked in appropriate numbers to achieve the thickness required to produce the desired blanket.

The fleece layer may be laminated before the low-temperature firing, or after firing and before the anti-friction treatment.

Thereafter, the fleece laminate is needle punched at a density of about 1 to 60 times/-.

The laminate after needle punching is approximately 800 to 130
The fibers are converted into crystalline alumina fibers by firing in a high temperature oxidizing atmosphere at 0°C.

〔Example〕

Aluminum oxychloride aqueous solution (solid content concentration 50%).

A I20, equivalent concentration 23%) to 1000ml, 20
% Silica Sol 520I 11.6% polyvinyl alcohol aqueous solution (700 ml) was added and concentrated at 40°C under reduced pressure.
A spinning stock solution with a viscosity of 30 poise was obtained. This spinning stock solution was spun by a centrifugal method, collected, and dried to obtain a precursor fiber fleece. This was baked in air at 600°C for 15 minutes. The obtained fleece of low temperature fired fibers was immersed in a lubricant (an aqueous emulsion of paraffinic mineral oil), dehydrated and dried, thereby attaching a lubricant of 2% by weight to the fleece.

Next, the 10 sheets of the treated 7 liss were stacked together, the resulting laminate was needle punched 30 times/cd using a needle punch machine, and then fired at 1250°C for 20 minutes to form crystalline alumina fibers. I got a blanket.

Product bulk density is 0.12 g/can", tensile strength is 1.4 kg/c1?, peel strength is 15 t/cm"
Met.

〔Effect of the invention〕

As mentioned above, in the present invention, treatment with an aqueous lubricant and needle punching are performed when the material becomes water resistant through low-temperature firing and has physical properties most suitable for needle punching, so a nonaqueous lubricant is used. It has many advantages over other methods, such as being safer, requiring less-expensive lubricants, and requiring simpler processing equipment.Furthermore, there is less fiber breakage caused by needle punching. This not only facilitates the needle punching process, but also increases the processing effect, making it possible to inexpensively and easily produce a blanket with excellent shape stability and strength without causing delamination.

Claims (2)

[Claims] (1) A fleece of alumina fiber precursor fibers is produced by spinning a fiber-forming solution of an aluminum compound, collecting the fibers into a fleece shape, and drying the fibers.The fleece of the precursor fibers is then fired at a low temperature. A water-based lubricant is applied to the fleece, and then or in any of the above steps, the fleece is laminated to the thickness required for blanket production, and the resulting lubricant-treated fleece laminate is needle punched. A method for producing an alumina fiber blanket characterized by firing at a high temperature until crystalline alumina fibers are produced from low-temperature fired fibers. (2) The manufacturing method according to claim 1, wherein the low-temperature firing of the precursor fiber is carried out in a temperature range where crystalline alumina is not substantially produced from the aluminum compound in the fiber.