JPS6246927A - Production of cylindrical or columnar glass - Google Patents

Abstract

PURPOSE:To produce cylindrical or columnar glass of high quality with high mass productivity by pouring sol into a cylindrical vessel to form cylindrical or columnar gel, rotating the gel at a proper rotational frequency for a prescribed time, and drying and sintering the gel. CONSTITUTION:Sol is poured into a cylindrical vessel 1, and while the vessel 1 is rotated with a motor 2, the sol is converted into gel to form cylindrical or columnar gel. This gel is rotated for a prescribed time. The rotational fre quency during the rotation of the gel is preferably regulated so that centrifugal force produced by the rotation is made lower than 500G (G is the acceleration of gravity) at the outside of the cylindrical or columnar gel. The suitable rota tion time after the gelling is 30min-100hr. Thus, the deformation of the cylindri cal or columnar gel immediately after gelling is prevented. The gel is then taken out, dried and sintered. By this method, cylindrical or columnar glass having high roundness is obtd. in a high yield without causing warping or crack ing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing cylindrical or cylindrical glass by the Grugel method.

[Summary of the invention]

The present invention is a method for manufacturing cylindrical or cylindrical glass using the sol-gel method, in which a sol is poured into a cylindrical container and gelled to create a cylindrical or cylindrical gel, which is then dried and sintered to vitrify it. By applying rotation for a predetermined period of time after gelation, deformation of the cylindrical or cylindrical gel immediately after gelation is eliminated, and roundness, warpage, and yield are improved.

[Conventional technology]

The glass manufacturing method using the sol-gel method is currently attracting a lot of attention because it can produce high quality glass at low cost. In addition, a method for manufacturing cylindrical or cylindrical glass, in which a sol is poured into a cylindrical container to create a cylindrical or cylindrical gel, followed by drying and sintering, is particularly useful as a method for manufacturing optical fiber base materials at low cost. Very important.

Note that to determine whether or not the sol has gelled, the sol is placed in a beaker, etc., and when the sol no longer flows even when the sol is tilted, it is considered to have "gelled."
The criteria for ``gelation'' are in accordance with this. Up to now, when performing rotational gelation, the sol has been gelatinized for 30 minutes.
The usual method is to stop the rotation within a few minutes, leave the cylindrical container to ripen, and once it can be removed from the container, place it in a drying container and dry it. method is commonly practiced.

[Problems and objects to be solved by the invention] However, in the above-mentioned conventional technology, the gel is still soft immediately after gelation, and the resulting gel deforms due to gravity, and by the time it is dried, it becomes completely soft. The roundness etc. will deteriorate. Moreover, the strain during this time is preserved, and the cylindrical or cylindrical gel may warp or crack during the subsequent drying and sintering steps. The quality of the cylindrical or cylindrical glass obtained in this manner deteriorates, the yield rate deteriorates, and mass productivity deteriorates significantly. The present invention is intended to solve these problems, and its purpose is to eliminate the deformation of cylindrical or cylindrical gel immediately after gelation, and to mass-produce high-quality cylindrical or cylindrical glass with ease. An object of the present invention is to provide a method for producing cylindrical or cylindrical glass.

[Means for solving problems]

The method for manufacturing cylindrical or cylindrical glass of the present invention includes pouring a sol into a cylindrical container, gelling it to create a cylindrical or cylindrical gel 3, and then drying and sintering the sol to vitrify it. In a method for producing cylindrical or cylindrical glass by a gel method, rotation 2 is performed for a predetermined period of time after gelation.
It is characterized by adding. Here, the step of pouring the sol into a cylindrical container and gelling it involves filling the cylindrical container with the sol and gelling it while rotating or leaving it to stand still.
The process of creating a cylindrical gel or the step of creating a cylindrical gel by pouring the sol 2 into a cylindrical container and turning it into a gel, and then immediately pouring the sol and rotating it to create further layers of cylindrical gel as necessary. After repeating the process, the process immediately consists of pouring the sol and gelling it while rotating or leaving it to stand still to create a cylindrical or cylindrical sol.

The number of rotations after gelation is not desirable because if the centrifugal force due to rotation is greater than 500 G on the outer periphery of the cylindrical or cylindrical gel, the cylindrical gel will break due to the centrifugal force.

The gel is soft immediately after gelling, but quickly hardens over a certain period of time, and then gradually shrinks. This time can be controlled during the sol preparation process. If the cylindrical or cylindrical gel shrinks to the extent that a gap is created between the cylindrical or cylindrical gel and the container used for rotation, then the cylindrical or cylindrical gel has sufficiently hardened, and the gravity Deformation becomes extremely small. After gelation, it takes about 30 minutes to reach this state [4kl iF:
FJ I% + 61 f +-) W4
J-Db 1ull ul ## -7-
A →: 1 1 4y A: Rite,
The rotation time after gelation is preferably 30 minutes or more, and 1
Even if the rotation continues for more than 100 hours, the iik productivity will only decrease, so it is preferable to keep the rotation for 100 hours or less.

[Effect]

Immediately after gelation, the gel is soft and easily deformed, but as it continues to rotate even after gelation, an even force of gravity is applied per unit time in the radial direction of the cylindrical or cylindrical gel, which worsens the roundness. Never. Therefore, a cylindrical or cylindrical glass with very good roundness can be obtained. In addition, while the gel is soft from immediately after gelation to drying, the distortion of the gel is reduced, so it is less likely to warp or crack during the subsequent drying and sintering processes, improving yield and facilitating mass production. is significantly improved.

As described above, according to the present invention, high quality cylindrical or columnar glass 'E-1 can be obtained with good productivity.

〔Example〕

Hereinafter, the present invention will be explained in detail according to examples. , [11) 2N hydrochloric acid 80
01, commercially available fine powder silica 500 t * fine powder germanium 62 created by hydrolysis of metal alkoxide
9 were mixed, vigorously stirred, subjected to ultrasonic irradiation, centrifugation, and filtration to obtain a highly homogeneous sol. In this sol [LIN
After adding ammonia water and adjusting the pH value to 4.2, it was filtered, and 1962tnL was 5c! The mixture was poured into a cylindrical container made of tetrafluoroethylene with a size of nφ x 1 m and rotated around the tube axis at 200 rpm to form a gel in 60 minutes.

After gelation, continue at 2000 rpm for 30 minutes and 1 hour.

Samples were prepared by continuing rotation for 3 hours and 5 hours. For comparison, a sample was also prepared in which the rotation was stopped when gelation occurred. The obtained cylindrical gel was dried at 60°C for 4i1 minutes, and the obtained dry gel was heated to 1200°C to form a φ2.5 on
A cylindrical quartz-based glass containing 50 ann of 3m01% germanium was obtained. The results shown in Table 1 were obtained by examining 100 of each type.

Table 1 (Note) For everyone, the average value of 100 pieces and the roundness are the values at the outer periphery (the following examples are also the same). The yield has also been clearly improved.

Example Z Silica sol was prepared in the same manner as in Example-1, the pH value was adjusted to 4.2, and the 1962rnl was prepared) 57
k Pour into a cylindrical container made of oleoethylene for 2000r
It gelled after 60 minutes when rotated at pm. After gelation,
Subsequently, samples were prepared by rotating for 5 hours at the rotation speed shown in Table 2. The obtained cylindrical gel was dried at 60°C for 2 weeks, the obtained dry gel was heated to 1200°C, and Z5 subφ
A cylindrical quartz-based glass of ×50- was obtained.

(Note) The centrifugal force due to rotation is the value at the outermost periphery of a cylindrical or cylindrical gel (the same applies to the following examples). From Table 2, the rotation speed after gelation is, even if the centrifugal force due to rotation is cLIGg degrees, It can be seen that the roundness, warpage, and yield are clearly improved. Furthermore, if a centrifugal force of more than 500G is applied, the gel will crack due to the centrifugal force, and the yield will drop sharply, which shows that it is desirable that the centrifugal force due to rotation be 500G or less.

Examples & Example 1. Create silica sol in the same manner as 'PH
Adjust the value to 55 and convert that 1962m1 to 5cntφX1
The mixture was poured into a cylindrical container made of tetrafluoroethylene, and gelatinized while rotating at 1000 rpm. Approximately 1
It gels after 20 minutes, and continues to gel for 10 DOrs after gelling.
pm and the time rotation shown in Table 3? A subsequent sample was created. The obtained cylindrical gel was dried at 60°C for 2 weeks, the obtained dried gel was heated to 1200°C, and 2.5 crnφ×
A 50α cylindrical quartz glass was obtained.

From Table 5, it can be seen that the deformation of the tubular gel is less when the rotation is performed for a longer time, but the yield is gradually lowered.

Example 4 A sol was prepared in the same manner as in Example 1, and the pH value was 4.2.
The 1962rnL was poured into a cylindrical container made of tetrafluoroethylene of 5CItIφ x 1m, and
When rotated at 000 rpm, gelation occurred in 60 minutes. After gelation, samples were prepared by continuing to rotate at 2000 rpm for 5 hours, then decreasing the rotation speed to 200 rpm and continuing to rotate for the time shown in Table 4. The obtained cylindrical gel was
Dry gel E-1200 obtained by drying at 0°C for 2 weeks
When heated to °C, a cylindrical quartz-based glass of 2.5-φ×50 rrn was obtained.

From Table 4, it can be seen that after gelation, if the rotation is continued for a long time, the roundness will decrease.
It can be seen that warpage and yield are improved. However, if the gel rotation time exceeds 100 cycles, there will be almost no difference in roundness, warpage, or yield.
It can be seen that it is not beneficial to continue spinning for more than an hour.

Table 4 Example 1
07 was added and stirred vigorously to complete the hydrolysis reaction.

This is called hydrolyzate A. Next, ethyl silicate 10
After adding 13f of 0F, 102N hydrochloric acid and stirring under water cooling for 2 hours, tetraethoxygermanium 171 was added and stirred. After continuing stirring for 1 hour, 0.02N
Hydrochloric acid 229% was added and stirred to complete the hydrolysis. This is called hydrolyzate B.

On the other hand, ethyl silicate 1086f, [LO5N ammonia water 575y and ethanol 2300r? In addition, the mixture was stirred to complete hydrolysis and a solution containing ultrafine powdered silica was prepared. This was concentrated to about 600 d, and the pH value was adjusted to 4.5 using 2N hydrochloric acid. This is 9
/10 is taken as fine powder silica dispersion A, 1/
10 was taken as fine powder silica dispersion B.

Mixing the hydrolyzed solution A and the finely powdered silica dispersion solution A,
The mixture was vigorously stirred and filtered to obtain a highly homogeneous sol for cladding. After adding α1N ammonia water to this sol and adjusting the pH value to 4.8, it was filtered.
When sj was poured into a polyethylene TY5 cylindrical container with 5 (Mlφ×1 wing) and rotated around the tube axis at 2000 rpm, it gelated in 60 minutes and a cylindrical wet gel for cladding was created.

On the other hand, the hydrolyzed solution B and the fine powder silica dispersion B were mixed and vigorously stirred to obtain a highly homogeneous core sol. After adding Q and IN ammonia water to this sol and adjusting the pH value to 55, it was filtered and degassed, and 7811 was poured into the cylindrical wet gel for cladding immediately after gelation, and rotated at a rotation speed of 200 rpm. It gelated in 25 minutes. After gelation, samples were prepared by continuing to rotate at 200 rpm for 30 minutes, 1 hour, and 5 hours. For comparison, a sample was also prepared in which the rotation was stopped when the core sol gelled. The prepared cylindrical gel was dried at 60° C. for 2 weeks to obtain a dry gel. The prepared dry gel was heated to 200°C at a heating rate of 50°C/h and held for 1 hour to perform desorption water treatment. Continue to 450℃ at a heating rate of 30℃/h.
The decarbonization process was performed by heating the sample to 100% and holding it in this state for 5 hours.

Next, heat at a heating rate of 5°C/i to 770°C.
After maintaining the state in which Ct with a flow rate ratio of 5 = 1 for gas and He gas was pumped into the furnace for 2 hours, 9
The sample was heated to 00° C. and held for 1 hour using He gas and oxygen gas at a flow rate ratio of 3:1 to carry out dechlorination treatment.

After that, it was heated to 1200℃ at 1℃/- while flowing He gas.
It was heated to 2.5 cTMφ
A cylindrical quartz 7 Aipah base material with m01% was obtained.

Table 5 (Note) The rotation time is the time elapsed from the time when the outermost gel gelled. (The same applies to the following Examples) From Table 5, by rotating the core even after gelation, the roundness, warpage, and yield were clearly improved.

Example & Ethyl silicate 980F and [LO2N hydrochloric acid 800y were mixed and stirred to prepare a hydrolyzed solution.

On the other hand, ethyl silicate 980r, 0.05N ammonia water 340? 1400 S' of ethanol was added and stirred to complete the hydrolysis and obtain an ultrafine powdered silica solution.

After concentrating this to 540-, the pH value was 55 with 2N hydrochloric acid.
Adjusted to. The above hydrolyzed solution was mixed with this, and 1.51% of commercially available titanium dioxide fine powder was added and vigorously stirred.
After centrifugation and filtration, adjust the P4 value to 4.
After adjusting to 8 and filtering, the 1962-
The mixture was poured into a polypropylene cylindrical container and left to gel. After gelation occurred after 60 minutes, the tube was rotated around the tube axis at 20[fflOrpm] for the time shown in Table 6 to obtain a cylindrical gel. This was dried at 60℃ for 2 weeks to give 187
When heated to 0° C., a cylindrical quartz-based glass with a titanium concentration of 12 mo1% and a size of 2.5 tnrφ×50 m was obtained.

Table 6 Table 6 shows that rotation after gelation clearly improves roundness, warpage, and yield.

Example Z In the same manner as in Example 5, the cladding sol was converted to [LI
After adding N ammonia water and adjusting the pH value to 4.8, filtration was performed and the 1570- was 5c! Pour into a cylindrical container made of nφ×1 chicken polyethylene and heat around the tube axis to 200
When rotated at rpm, gelation occurred in 60 minutes and a cylindrical wet gel for cladding was created.

On the other hand, the core sol was adjusted to a pH value of 55 with 0.1N ammonia water, filtered and degassed, then poured into a 62v11 cylindrical wet gel immediately after gelation, and rotated at a rotational speed of 2000 rpm. It gelated in 25 minutes.

After gelation, continue to rotate for 3 hours, then rotate at 600 rpm.
Samples were prepared by lowering the rotation speed to m and continuing rotation for the time shown in Table 7. The obtained cylindrical gel was dried at 50° C. for 3 weeks to prepare a dry gel. The prepared dry gel was heated to 200° C. at a heating rate of 30° C./h and held for 1 hour to perform desorption water treatment. Next, the heating rate is 50°C
/Q to 450° C. and held in this state for 5 hours to perform decarbonization treatment.

Next, heat at a heating rate of 5°C/i to 770°C.
After maintaining the state in which gas and He gas were fed into the AT and E furnaces at a flow rate ratio of 5:1 for 2 hours, the temperature was increased at the same heating rate at 9.
The mixture was heated to 00° C. and maintained for 1 hour using He gas and oxygen gas at a flow rate ratio of 3=1 to carry out dechlorination treatment.

After that, while pouring 2 He gases, the temperature was 12σ・0 at 1℃/i.
It was heated to ℃ to make it non-porous, held at this temperature for 1.5 hours by 5 people, and vitrified to 2.51℃. FFlφ
A cylindrical quartz fiber base material 3 with a Gθ concentration of 5m01% was obtained.

Table 7 Rotating for a longer time than Table 7? As the process continues, it can be seen that roundness, warpage, and yield are improved. However, if the rotation time of the gel exceeds 100 hours, the roundness, warpage, and yield will hardly change, so it is not beneficial to continue rotating the gel for more than 100 hours after the gel has died.

In this example, the glass containing Ge, Ti, etc. was described, but it was confirmed that the present invention can be applied to glasses containing other components in exactly the same way.

〔Effect of the invention〕

As described above, according to the present invention, the sol-gel method involves pouring a sol into a cylindrical container, gelling it to create a cylindrical or cylindrical gel, and then vitrifying it by drying and sintering. In the method for manufacturing cylindrical or cylindrical glass, by applying rotation for a predetermined period of time after gelation, deformation immediately after gelation is eliminated, and roundness, warpage, and yield are significantly improved. Therefore, high-quality, high-precision cylindrical or cylindrical glass can be manufactured easily and with good productivity, so it can be applied in many fields, especially as an optical fiber base material.
Alternatively, it is extremely effective for producing fiber base materials for rod-in-tubes, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a rotating device used to prepare a cylindrical or cylindrical gel in an embodiment of the present invention. 1...Cylindrical container 2...Motor 5...Bearing 4...Fixing jig 5...Guide rail 6...Support stand and above

Claims (3)

[Claims] (1) A method for producing cylindrical or cylindrical glass using the sol-gel method, in which a sol is poured into a cylindrical container and gelled to create a cylindrical or cylindrical gel, which is then dried and sintered to vitrify it. A method for producing cylindrical or cylindrical glass, characterized in that rotation is applied for a predetermined period of time after gelation. (2) The rotation speed after gelation is such that the centrifugal force due to rotation is less than 500G (G: gravitational acceleration) on the outer periphery of the cylindrical or columnar gel. A method of manufacturing the cylindrical or cylindrical glass described above. (3) The method for producing cylindrical or columnar glass according to claim 1 or 2, wherein the rotation time after gelation is 30 minutes or more and 100 hours or less.