JPH01221517A - Production of precursor gel fiber for ceramics - Google Patents

Abstract

PURPOSE:To obtain the subject fiber of an uniform shape useful as a raw material for a heat insulating material, etc., by carrying out extrusion spinning of a precursor material of ceramics from a nozzle while making a zone near the nozzle outlet into an atmosphere inert to gelation and a zone apart therefrom into an atmosphere active to gelation. CONSTITUTION:Water containing a small amount of HCl is added to tetraethoxysilane, etc., and stirred while being heated to prepare a viscous precursor material of ceramics. The resultant material is discharged from a spinning nozzle 1 and the obtained discharged yarn 2 is passed through an atmospheric zone 4 inert to gelation filled with gaseous nitrogen, etc. introduced by a conduit 3 for supplying an inert gas equipped near the nozzle outlet and subsequently passed through an atmospheric zone 6 active to gelation filed with gaseous nitrogen, etc., containing ammonia-steam introduced by a conduit for supplying an active gas apart from the nozzle outlet to carry out gelation of the discharged yarn 2 and provide the aimed precursor gel fiber of ceramics.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing ceramic precursor gel fibers that can produce ceramic fibers by firing, and particularly relates to a method for producing ceramic precursor gel fibers that can produce ceramic fibers by firing. This invention relates to a method for producing fibers.

(Prior Art) Ceramic fibers are widely used in industry, and are used, for example, as heat insulating materials, vibration isolating materials, adsorbents, filtration materials, reinforcing materials for composite materials, and the like.

Ru.

For example, in the case of glass fibers, glass molten at high temperature is extruded from a nozzle, cooled, and made into fibers.

Regarding alumina fibers, there are the following main manufacturing methods.

(a) ICI method: A 1 z(OH)x (CH2O
00) Y.

A water-soluble organic polymer such as polyethylene oxide is added to an aqueous solution of an aluminum salt such as (X + Y) = 6 to give it viscosity, and a silicon compound is added to give strength to the fibers. The spun material is fired at 1000°C or higher.

3M method: Alumina sol containing ions such as HCOO- and CH3COO- is mixed with silica sol and boric acid to give strength to the fibers, and the concentrated solution is extruded from a nozzle and deposited on a belt conveyor, 1oo
Fire at o'c or above.

(c) D u P on modulo: tx Alt
Fine powder of os and Al z(OH)s Cl・2.2H2
0 and Mg(l□.6H20) are mixed with water to form a viscous slurry, which is then spun.

This is fired at 1000°C or higher to form α-AlzO.
3 and further heat and bake at 1500″C,
At this time, MgO becomes a sintering aid. Furthermore, in order to increase the strength of the fiber, it is coated with SiO□.

(d) Sumitomo Chemical Law: (AI!, R-0)n (R=
A polymer containing silica (alkyl, alkoxy, carboxylic acid groups, etc.) is dissolved in an organic solvent to form a viscous liquid, and a silicate ester is added to this and spun.
Obtain ltOx fibers.

Moreover, regarding zirconia fibers, there are the following methods as main manufacturing methods.

(a) UCC method: Zr to which YCl:l was added as a stabilizer (e, after immersing polymer fibers or woven fabrics in the solution as a medium, removing inorganic salts with a centrifuge, drying for 500 min.
Bake at °C.

(b) ICI method: A liquid containing zirconium is sucked out from a nozzle, blown away with high-pressure gas, made into fibers, and then fired.

Meanwhile, a ceramic precursor viscous material is synthesized, spun,
A method of manufacturing ceramic fibers by heating and firing the ceramic precursor gel fiber is also known, and this method is disclosed in Japanese Patent Application Laid-Open Nos. 52-34024 and 1977-77724.
It is stated in

JP-A No. 52-34024 discloses aluminum alcoholate and silicon alcoholate, or titanium alcoholate and silicon alcoholate, which are prepared to contain silicon oxide at a ratio of 10 to 95% when converted into oxides. or a mixture of aluminum alcoholate, titanium alcoholate and silicon alcoholate,
Alternatively, a suitable amount of alcohol can be added to this, mixed and reacted at a temperature from room temperature to around 120°C, and then left in the air to slowly hydrolyze, resulting in a viscous and spinnable solution. describes a method for producing alumina-silica-based, titanium oxide-silica-based, and alumina-titanium oxide-silica-based ceramic fibers by heating the fibrous material spun from this solution to convert it into oxides. .

In addition, in JP-A-54-77724, a mixture of zirconium alcoholate and silicon alcoholate prepared so as to contain zirconium oxide in a proportion of 5% by weight or more when converted into an oxide, or an appropriate amount thereof, is disclosed. The fibrous material spun from this solution is heated to convert it into an oxide and produce zirconium oxide-silicon ceramic fibers. It describes the method of manufacturing.

(Problems to be Solved by the Invention) The method for producing ceramic fibers as described above, which is practiced industrially, has limitations on the composition in the case of the melting method for producing glass fibers, and In the case of manufacturing methods, only short fibers can be obtained,
It has problems such as low production efficiency.

On the other hand, the method of obtaining ceramic precursor gel fibers by spinning ceramic precursor viscous substances obtained using metal alkoxides etc. as a starting material requires that continuous long fibers can be produced and that industrially rational process design is required. Although the spinning methods disclosed to date have advantages such as the possibility of There are many technical challenges in transitioning to extrusion spinning, which has high productivity.

In order to obtain a ceramic precursor gel fiber by extruding a ceramic precursor viscous substance through a spinning nozzle, the fibrous ceramic precursor that comes out of the nozzle must be quickly gelled while retaining its shape. However, when heating hot water and extruding a ceramic precursor viscous substance through a nozzle, the substance may gel and adhere to the nozzle opening, resulting in ceramic precursor gel fibers with disordered shapes, and continuous spinning is difficult. Fibers with a uniform shape could not be obtained continuously, and reproducibility was poor.

It is an object of the present invention to overcome these drawbacks.

(Means for Solving the Problems) The object of the present invention is to provide a method for obtaining ceramic precursor gel fibers by extrusion-spinning a ceramic precursor viscous material from a nozzle, in which a ceramic precursor viscous material is used in the vicinity of the nozzle exit. The problem was solved by a method for producing ceramic precursor gel fibers, which is characterized by creating an atmosphere that is inert with respect to gelation, and creating an atmosphere that is active in terms of gelation of the ceramic precursor viscous substance at a location away from the vicinity of the nozzle outlet.

The figure illustrates one embodiment of the invention. 1st
In the figure, the spun yarn 2 spun from the spinning nozzle 1 passes through an inert atmosphere section 4 where an inert gas is introduced from an inert gas conduit 3 to create an inert atmosphere, and its door shape is ensured. Next, the active gas is introduced from the active gas conduit 5 and passes through the active atmosphere section 6 where an active atmosphere is created, where it is gelled and becomes gel fibers.

At this time, if the atmosphere is active for gelation from directly below the nozzle, the ceramic precursor viscous substance extruded from the nozzle will gel on the nozzle surface, and the gel will adhere to the nozzle opening, making continuous spinning difficult. .

On the other hand, in order to prevent the ceramic precursor viscous material extruded from the nozzle from gelling on the nozzle surface and adhering to the nozzle opening, if an inert atmosphere with respect to gelation is created after the nozzle, the fibers extruded from the nozzle It takes a long time for the ceramic precursor viscous substance to gel, making it impractical, and in extreme cases, it becomes unable to maintain its shape and spinning becomes impossible.

The length of the inert atmosphere part is not particularly limited, but it is preferably 1 cIa or more to prevent gelation at the nozzle part, and preferably 50 cm or less to promote gelation quickly. The length of the active atmosphere section is appropriately set based on the spinning speed, the gelation speed of the viscous precursor material, and the like.

The ceramic precursor viscous substance used in the present invention is a precursor that can ultimately become a ceramic, has a viscosity that allows spinning, and is a substance that gels by reacting with a substance active in gelation.

Examples of such substances include (1) metal alkoxide M(OR)n (M is a metal,
a viscous substance obtained by hydrolyzing and polycondensing R (R is an alkyl group), (2) an inorganic polymer, e.g. M(R), -1-;

+M(R'), -R+.

(3) Metal salts (hydroxides, oxides, carbonates, nitrates, organic acid salts, etc.), organic polymers (polyacetic acid Examples include viscous substances prepared by adding vinyl partial hydrolysates, etc.).

Among these, viscous sols synthesized from those containing metal alkoxides or their derivatives as main components are preferred ceramic precursor viscous materials from the viewpoints of compositional diversity, ease of synthesis, control of gelation, etc. be.

In addition, the metal alkoxides referred to here refer to alkoxides of metals or metalloid elements such as silicon, titanium, zirconium, germanium, and aluminum, and if the compound has two or more alkoxy groups, an alkyl group, an allyl group, It may also have an organic residue such as an aryl group or a vinyl group. Examples of such compounds include silane compounds such as tetramethoxysilane, tetraethoxysilane, trimethoxymethylsilane, and triethoxyphenylsilane, tetraisopropoxytitanium, tetrabutoxytitanium, triisopropoxyaluminum, and tetrabutoxyzirconium. Ru.

Derivatives of metal alkoxides include compounds in which part or all of the alkoxy group is substituted with glycols, β-diketone compounds, alkanolamines, organic acids, β-ketoamines, β-ketoesters, etc. point to

These metal alkoxides or derivatives thereof may be used alone or in combination of two or more. A ceramic precursor viscous substance is prepared by hydrolyzing and polycondensing these compounds by appropriate means.

The ceramic precursor gel produced in the present invention is a ceramic precursor viscous substance solidified so as to maintain its own shape by a substance active in gelation or by heat (temperature). Ceramic fibers can be obtained by drying and firing this by an appropriate means.

In the present invention, an atmosphere that is inert to the gelation of the ceramic precursor viscous substance and is held near the nozzle outlet is an atmosphere that does not affect the gelation of the ceramic precursor viscous substance. Body viscous substances do not gel.

For example, in the case of a ceramic precursor viscous material obtained by hydrolysis of a metal alkoxide, an atmosphere such as dry air, oxygen, nitrogen, He 2 , Ar 2 , Cot, etc. is inert to gelation.

Furthermore, the active atmosphere maintained at a location away from the vicinity of the nozzle outlet is an atmosphere active in gelling the ceramic precursor viscous substance. For example, in the case of ceramic precursor viscous materials obtained by hydrolysis of metal alkoxides, an atmosphere containing water vapor is an active atmosphere. The reaction can be carried out more effectively by creating an atmosphere containing other reaction promoting catalysts and taking measures to promote gelation.

(Function) In the present invention, the atmosphere near the exit of the spinning nozzle is inert with respect to gelation, and the atmosphere away from the vicinity of the nozzle exit is active with respect to gelation.
The ceramic precursor viscous substance extruded from the spinning nozzle does not gel at the nozzle exit, and therefore can be spun without causing any problems due to gelled substances adhering to the nozzle, and the fibers continue to flow. By passing through an active atmosphere with respect to gelation, gelation is promoted in this active atmosphere part, and ceramic precursor gel fibers in the form of continuous long fibers are obtained.

(Example) The present invention will be specifically explained below using Examples.

However, the present invention is not limited only to these examples.

Example 1 At room temperature, 100 parts by weight of tetraethoxysilane (Si(OCtHs)4) and 2 parts of ethanol
2 parts by weight were mixed well, and to this solution were added 22 parts by weight of ethanol, 8.6 parts by weight of water (molar ratio to tetraethoxysilane: 1), and 10.2 parts by weight of H (molar ratio to tetraethoxysilane: 0.01). A mixed solution was added, stirred, and then refluxed at 80°C for 1 hour.After this, air at a gas temperature of 25°C and a relative humidity of 50% was passed through the reaction system at 50°C.After 96 hours, the stringiness was determined. A viscous solution was obtained.

The obtained viscous sol was used as a ceramic precursor viscous substance. In the apparatus shown in Figure 1, N2 is used as an inert gas for gelation, and the inert gas atmosphere is N2.
When the aforementioned ceramic precursor viscous material was spun in an N2 atmosphere containing ammonia and water vapor as an active gas, no adhesion due to gelation was observed at the nozzle opening, and gelation quickly occurred in the active atmosphere. , continuous spinning was possible.

Comparative Example 1 The viscous sol shown in Example 1 was used as a ceramic precursor viscous substance.

In the apparatus shown in the figure, when the inert atmosphere section 4 and the active atmosphere section 6 were removed and the ceramic precursor viscous material was spun in the atmosphere, gelation progressed very slowly, even at a distance of 2 m from the spinning nozzle. It still remained in a sol state and no gel fibers were obtained.

Comparative Example 2 Silicon tetraethoxide 5i (OEt)4 of Example 1
The viscous sol obtained by hydrolyzing was used as a ceramic precursor viscous substance.

In the apparatus shown in the figure, the inert atmosphere section 4 was removed, the spinning nozzle 1 was directly connected to the active atmosphere, and the above-mentioned ceramic precursor viscous material was spun using N2 containing ammonia and water vapor as the active gas. The viscous sol extruded from the nozzle turned into a gel on the nozzle surface, and the gel adhered to the nozzle opening, making continuous spinning impossible.

Example 2 Diisopropoxy (ethyl acetoacetate) aluminum ((i C3H?0) ZA j! (OC(CN
3)=CHC(OC,N5)=O)) 100 parts by weight is mixed with 100 parts by weight of isopropanol, and a water-nitrogen mixed gas (water/gas mol=0. 24/1) was passed in an amount equivalent to 9 parts by weight as water and reacted at a temperature of 60°C for 8 hours, and a part of the solvent was removed under reduced pressure to form a yellow transparent viscous liquid (15 poise).
I got it.

The obtained viscous sol was used as a ceramic precursor viscous substance. In the apparatus shown in Fig. 1, N2 is used as an inert gas for gelation, the inert atmosphere part is set to Nz atmosphere, and N2 containing ammonia-steam vapor is used as the active gas, and the active atmosphere part is set to contain ammonia-steam vapor. When the aforementioned ceramic precursor viscous material was spun in an N2 atmosphere, no adhesion due to gelation was observed at the nozzle opening.
It quickly gelled in an active atmosphere and could be spun continuously.

Comparative Example 3 The viscous sol in Example 2 was used as a ceramic precursor viscous substance.

In the apparatus shown in FIG. 1, the inert atmosphere section 4 is removed,
When the above-mentioned ceramic precursor viscous material was spun using N2 containing ammonia and water vapor as the active gas by directly connecting the spinning nozzle 1 and the active atmosphere section 6, the viscous sol extruded from the nozzle formed a gel on the nozzle surface. The gel adhered to the nozzle opening, making continuous spinning impossible.

(Effects of the Invention) According to the present invention, when attempting to obtain ceramic precursor gel fibers by spinning a ceramic precursor viscous substance, there is no adhesion due to gelation at the nozzle opening, and the ceramic precursor gel fibers are continuously spun. It can be spun into yarn. Not only can spinning be performed without any hindrance at the nozzle opening, but also the spinning can be rapidly gelled, so that well-shaped fibers can be continuously obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus for carrying out the invention. 1: Spinning nozzle, 2: Spun yarn, 3: Inert gas supply conduit, 4: Active atmosphere section, 5: Active gas supply conduit, 6: Active atmosphere section. Figure 1

Claims (2)

[Claims] (1) In the method of obtaining ceramic precursor gel fibers by extrusion spinning a ceramic precursor viscous substance from a nozzle, the atmosphere near the nozzle exit is inert with respect to gelation of the ceramic precursor viscous substance, and the atmosphere is kept away from the nozzle exit vicinity. 1. A method for producing ceramic precursor gel fibers, characterized in that the atmosphere is active for gelation of a ceramic precursor viscous substance. (2) The method for producing a ceramic precursor gel fiber according to claim (1), wherein the ceramic precursor viscous substance is a viscous sol synthesized from a substance whose main component is a metal alkoxide or a derivative thereof.