JPH07108783B2 - Gel fiber manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a gel fiber used for producing a glass fiber. More specifically, it relates to a method for producing a gel fiber by a sol-gel spinning method, which is suitable for obtaining a high-strength oxynitride glass fiber, which is particularly preferable as a reinforcing material for a composite material such as FRP and fiber-reinforced cement.

Conventional technology To produce glass fiber, sol-gel method, melting method, N ₂
There are a gas blowing method, a NH ₃ gas treatment method for porous glass, and the like. Among these, the sol-gel method is a method of producing a glass at a much lower temperature than a conventional melting method by heating and dehydrating and condensing a liquid obtained by hydrolyzing a metal alkoxide. This method can be applied to any of various glasses such as oxide glass, oxynitride glass (oxynitride glass), and oxycarbonite glass, and can produce glass fibers having a wide range of compositions.

Further, in recent years, glass fibers having high strength have been mixed with these materials to form a composite as a powerful means for strengthening structural materials such as plastics and cement. Oxynitride glass has attracted attention as a glass fiber used for such a composite material.
Oxynitride glass has a structure in which oxygen atoms of oxide glass are replaced with nitrogen, and since the valence of this nitrogen is 3, it has a higher elastic modulus than conventional glass. Spinning of such oxynitride glass is generally performed by a sol-gel method.

In the production of glass fibers by the sol-gel method, first, an appropriate amount of water is added to an alcohol solution of various metal alkoxides to partially hydrolyze. Next, this solution is kept under predetermined conditions such as temperature to obtain a viscous solution (sol) of the chain polymer, and this sol is extruded from the spinning holes to obtain gel fibers. In order to obtain oxynitride glass fiber, the gel fiber is further heat-treated in a nitrogen and ammonia atmosphere to obtain a final product, glass fiber.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the conventional method for producing a gel fiber by the sol-gel method, it is difficult to stably maintain the sol physical properties necessary for spinning such as viscosity during spinning for a long time.

That is, in the conventional sol-gel method, selection of an alkyl group, or the degree of dilution with a solvent, the amount of added water, the type and amount of a catalyst, the retention temperature after hydrolysis, and the cooling of a solution have been variously studied. It is difficult to keep the sol solution for a long time within the range of 10 to 100 poise, which is a viscosity suitable for spinning, and gelation occurs within a short time of about 30 minutes, or even if gelation does not occur. It was not possible to achieve industrial production due to lack of filamentousness.

Means for Solving the Problems In obtaining the glass fiber by using the sol-gel method as described above, in order to keep the spinning viscosity of the sol constant for a long time, as a result of diligent studies, After the decomposition, by adding silica, it has been found that stable viscosity and spinnability can be obtained for a long time during spinning, and that it can be used for the production of glass fiber having high strength, and thus the present invention has been completed.

That is, the present invention provides a method for producing gel fiber, which comprises hydrolyzing a metal alkoxide, concentrating it, and then adding silica particles to spin a liquid obtained.

The metal alkoxide used in the present invention includes substitution,
Unsubstituted metal alkoxides and mixtures thereof are used to hydrolyze the aqueous solution to give a sol solution or a concentrated sol solution.

The metal alkoxide may be one that produces a gel by heat treatment and dehydration, and examples thereof include silicon alkoxide, zirconium alkoxide, titanium alkoxide, aluminum alkoxide, boron alkoxide, sodium alkoxide, and calcium alkoxide. , Silicon alkoxide, zirconium alkoxide, and titanium alkoxide are preferable.

It is particularly preferable to use a mixture of silicon tetraalkoxide, aluminum trialkoxide, zirconium tetraalkoxide and titanium tetraalkoxide in order to obtain an oxynitride glass fiber by performing nitriding treatment after spinning.

The alkoxy group is preferably a lower alkoxy group, and examples thereof include a methoxy group, an ethoxy group and a propoxy group. Therefore, as the metal alkoxide, silicon tetraethoxide Si (OC ₂ H ₅ ) ₄ silicon tetramethoxide Si (OCH ₃ ) ₄ tetraisopropoxy titanium Ti (iso-OC ₃ H ₇ ) ₄ tri-secondary butoxyaluminum, tetraiso Propoxy zirconium Zr (OC ₃ H ₇ ) ₄ etc. are preferred.

Further, examples of the aliphatic hydrocarbon group substituting the alkoxy group of the metal alkoxide include a lower alkyl group and a vinyl group, and examples of the substituted metal alkoxide substituted with a lower alkyl group include Si (OC ₂ H _{2 5) 3 (CH 3),} Si (OC 2 H 5) 2 (CH 3) 2, Si (OC 2 H 5) 3 (C 2 H 5), Si (OC 2 H 5) 2 (C 2 H 5 _{) 2, Si (OC 2 H} 5) 3 (iC 3 H 7), Si (OC 2 H 5) 2 (iC 3 H 7) 2, Ti (O-iC 3 H 7) 3 (C 2 H 5) _{, Ti (O-iC 3 H} 7) 2 (C 2 H 5) 2, Al (O-iC 3 H 7) 2 (CH 3), Al (O-iC 3 H 7) 2 (C 2 H 5) _{, Al (O-iC 3 H} 7) (CH 3) 2, B (OC 2 H 5) 2 (C 2 H 5), Ca (OC 2 H 5) (C 2 H 5) , and the like.

Further, examples of the aromatic hydrocarbon group substituting the alkoxide group of the metal alkoxide include a phenyl group or a phenyl group substituted with a lower alkyl group such as a methyl, ethyl or propyl group.

Furthermore, examples of the alkyl-substituted amino group that substitutes the alkoxy group of the metal alkoxide include an amino group substituted with a lower alkyl group such as a methyl, ethyl or propyl group.

As the aqueous solvent containing the metal alkoxide or the mixture of the metal alkoxide and the substituted metal alkoxide, a mixed solution of water and a lower alcohol such as methanol, ethanol, propanol or the like is used as in the conventional method.

As the hydrolysis catalyst, hydrochloric acid, sulfuric acid, aqueous ammonia solution or the like is used as in the conventional method.

When an aqueous solution containing a metal alkoxide and / or a substituted metal alkoxide is hydrolyzed into a sol solution,
The hydrolysis catalyst may be added to these aqueous solutions and stirred at room temperature, but the temperature may be slightly elevated to accelerate the hydrolysis reaction. The hydrolysis reaction may be carried out by simultaneously adding and mixing a metal alkoxide, a substituted metal alkoxide, an aqueous solvent and a hydrolysis catalyst.

The sol solution obtained by the above hydrolysis is concentrated to obtain spinnability suitable for spinning. Concentration in a constant temperature bath, temperature
The temperature is 30 ° C or higher, the boiling point of the solvent or lower, and the relative humidity is 0 to 30%, and the volume is 1/4 to 2/5. Then, silica powder is added, and the mixture is stirred and concentrated again. The silica powder added to the sol solution is preferably a fine powder, and has a particle size of 0.05 to 0.
2 μm fine silica powder is preferred. If the particle size exceeds 0.2 μm, preferable spinnability cannot be obtained.

The addition amount of silica powder is preferably 0.1 to 10% by weight. If the amount added exceeds 10% by weight, spinnability is not obtained, while if it is less than 0.1% by weight, gelation occurs in a short time.

The preferred viscosity of such a concentrated sol solution is 10-100 p
It is oise. If it is less than 10 poise, the viscosity is so low that agglomeration between particles does not occur during spinning and spinnability cannot be obtained. Again 100p
If it exceeds oise, agglomeration of some particles will start in the solution, yarn breakage will occur during spinning, and spinning for a long time becomes impossible.

To spin the concentrated sol solution into a fibrous gel, for example, a method of bringing the tip of a glass rod or the like into contact with a concentrated sol having spinnability, a method of continuously pulling out with a winder, or a concentrated sol Is maintained at a low temperature of room temperature or lower, and is made to flow out from a spinneret having predetermined pores within the above viscosity range and spun.

The gel glass fiber thus obtained can be burned at a high temperature in ammonia gas and / or nitrogen gas to introduce nitrogen.

Action In the production method of the present invention, by adding silica after hydrolysis, a stable viscosity and spinnability can be obtained for a long time during spinning.

EXAMPLES Next, the present invention will be described more specifically by way of examples.

Example 1 The following metal alkoxide and ethanol were mixed and
Stir for minutes.

Monomethylethoxysilane Si (Me) (OC ₂ H ₅ ) ₃ 150ml Tetraethoxysilane Si (OC ₂ H ₅ ) ₄ 50ml Titanium isopropoxide Ti (iso-C ₃ H ₇ ) ₄ 15ml Ethanol 150ml To the obtained alkoxide solution , Water 20 ml and ethanol
50 ml of the mixture was added and stirred for 1 hour. Then, this solution was concentrated in a thermostat (80 ° C.) to a volume of about 1/3. Fine silica powder (trade name: Aerosil, West Germany)
1 g of Degussa Co., particle size 0.05-0.2 μm) was added, and the mixture was stirred and concentrated again. 8 after the solution becomes viscous (about 50 poise)
Filtered using a 0 mesh filter. This solution was transferred to a container with a hole (1.5 mmφ) in the bottom, spun, and rolled (2
It was wound into 0 cmφ and 30 cm length).

In FIG. 1, the time course of the viscosity of the viscous sol solution at room temperature is indicated by ●. The winding speed (spinability) and the number of yarn breaks are shown in Table 1 below.

Examples 2 to 5 Glass fibers were spun in the same manner as in Example 1 except that the addition amount of fine silica powder was changed. The winding speed and the number of times of thread cutting are similarly shown in Table 1.

Comparative Example 1 A glass fiber was produced in the same manner as in Example 1 except that the fine silica powder was not added. The results are shown in Table 1. The change in viscosity with time (maximum holding time in the conventional method) is shown by ◯ in FIG.

As is clear from Table 1 and FIG. 1, according to the present invention, the holding period of the viscosity at which spinning is possible is extended by about 5 times, and the winding speed is also increased by about 20 times, as compared with the conventional method. Glass fiber having high strength can be stably produced.

EFFECTS OF THE INVENTION According to the present invention, the viscosity of the concentrated sol can be maintained at a spinnable time for a long time, and the number of thread cuttings during spinning is significantly reduced. For this reason, it has become possible to stably and continuously spin glass fibers having extremely high strength in a high yield. In addition, the winding speed has been improved about 20 times compared to the conventional one, and the cost can be reduced.

[Brief description of drawings]

 FIG. 1 is a graph showing changes in spinning solution viscosity with time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Kada 1 Nishinokyo Kuwabara-cho, Nakagyo-ku, Kyoto-shi, Shimadzu Corporation Sanjo Plant (72) Inventor Haruo Osafune Nishinokyo-Kuwabara-cho, Nakagyo-ku, Kyoto-shi, Kyoto Shimadzu Sanjo Factory

Claims (4)

[Claims] 1. A method for producing a gel fiber, which comprises hydrolyzing a metal alkoxide, concentrating it, and then adding silica particles to spin a liquid obtained. Wherein the metal alkoxide is _{Si (OC 2 H 5) 4} , Si (OH 3) (OC 2 H 5) 3, Ti (iso-OC 3 H 7) 4, Al (sec-OC 4 H 9) _The method according to item (1) above, which is an alkoxide selected from the group consisting of ₃ and Zr (iso-OC ₃ H ₇ ) ₄ . 3. The method according to item (1), wherein the silica particles have a particle size of 0.05 to 0.2 μm. 4. The method according to item (1), wherein the silica particles have a particle size of 0.1 to 10% by weight.