JPH09169548A - Heat resistant porous glass fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the above porous glass fibers less liable to the reduction of the strength at a low production cost in a short acid treatment time without requiring reheating for phase separation by adding a TiO2 -base component to the compsn. of borosilicate glass fibers. SOLUTION: A component readily soluble in an acid in glass fibers is leached out to produce the objective porous glass fibers contg. at least 90.0-98.0wt.% SiO2 and 0.5-3.0wt.% TiO2 . The specific surface area of the porous glass fibers is preferably 150-500m<2> /g. When the strength of the porous glass fibers is not satisfactory or the fibers are applied to a use requiring heat resistance at >=650 deg.C, the fibers are further heated at 600-800 deg.C. The compsn. of the glass fibers as starting material consists, e.g. of, by weight, 50-60% SiO2 , 10-20% Al2 O3 , 20-30% B2 O3 , 0.5-5% CaO, 0-4% MgO, 0-0.5% Li2 O+Na2 O+K2 O, 0.5-5% TiO2 and 0-0.3% Li2 O.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a porous glass fiber obtained by treating glass fiber with an acid, or
The present invention relates to a heat resistant glass fiber obtained by further heating this porous glass fiber.

[0002]

2. Description of the Related Art Acid-soluble components are dissolved out by treating glass fibers with an acid and dried as porous fibers having a large amount of SiO ₂ components, which are used as a dehumidifying agent or a deodorizing material for bad odors in filters, It can be used as an ion exchanger, an ion separator, an adsorbent, a gas-liquid separator and a catalyst. The porous fiber and the fiber containing a large amount of silica component, which is obtained by further heating the porous fiber at a higher temperature to increase the tensile strength of the fiber, are milled fiber, chopped fiber, paper, felt, yarn, and roll. -Bingya-
It can be used in the form of a cloth, cloth or the like.

Milled fiber, chopped fiber
Is friction material, paper is heat resistant, flame resistant coating, felt is heat insulating material,
The yarn is woven, the roving yarn is gland packing,
The glass cloth can be used as a heat resistant glass cloth, as a heat insulating material, a heat insulating material, a sound absorbing material required to have heat resistance, or as a surface material thereof. A method for producing a porous glass fiber used for these purposes and a glass fiber composition are disclosed in JP-B-44-2072 and JP-A-49-
It is disclosed in Japanese Patent Publication No. 94928 and Japanese Patent Laid-Open Publication No. 49-126927. However, these acid-treatable glasses are capable of stably spinning long glass fibers for a long time,
There have been various problems in terms of shortening the time required for acid elution and reducing the decrease in mechanical strength of the fiber. In order to solve these problems, Japanese Patent Laid-Open No. 2-1
The method for producing a porous glass fiber using a phase-separated glass as disclosed in Japanese Patent Publication No. 96035 is certainly an excellent method.

The content of the glass is a glass having a boric acid composition which is easy to be spun into phases, for example, Na ₂ O--B ₂ O ₃ --SiO ₂ glass, which is melted and formed into fibers by a known method, followed by heating at a high temperature. A heat treatment is applied to separate the acid-soluble Na ₂ O—B ₂ O ₃ phase into a hardly soluble SiO ₂ phase, and the acid-soluble portion is eluted by the heat acid treatment. By this treatment, the SiO ₂ phase is hardly melted and remains in its original shape to form a three-dimensional network structure, and porous glass fibers containing SiO ₂ as a main component are obtained. However, in order to phase-separate the components of the fiberized glass fiber, it is necessary to reheat to a temperature above the glass transition point, which is generally called 550 ° C., and energy, equipment, labor costs, etc., and the manufacturing cost increases because of one additional process. It is inevitable that the price will rise.

In order to avoid these problems, E glass fiber (composition of SiO _2), which is the main product of the glass fiber market at present, is used.
_{52-57wt%, Al 2 O 3 +} Fe2O3 12-
17 wt%, B ₂ O ₃ 5-12 wt%, CaO 1
6-24 wt%, MgO 0-4 wt%, Na ₂ O + K
₂ O 0-1.0 wt%. Acid-soluble component to elute the acid-soluble component to produce a fiber having a large amount of SiO ₂ component, as disclosed in JP-A-57-176233 and JP-A-5-176233.
No. 172876. In the former case, when the E glass fiber is in a strand or yarn state, it is treated with an acid for several hours to make it into a high silicate glass fiber, and then a woven fabric or a roll.
It is a processed product such as a pipe. E B of the whole glass fiber
₂ O ₃ , Al ₂ O ₃ , CaO, MgO, etc. are eluted and S
When the composition is high in iO _2, the phase separation is very small, so S
Since the iO ₂ skeleton is also broken, the strength is largely reduced and it is difficult to handle, and a stronger and easier-to-handle material has been desired.
In the latter case, the acid treatment is a treatment of only a part of the surface layer, so the decrease in strength is small, but a long treatment time is required and heat resistance is not sufficient.

[0006]

As described above, the conventional technique has advantages and disadvantages. The problem to be solved by the present invention is to develop a glass fiber that does not require reheating for phase separation, has a low manufacturing cost, takes a short time for acid treatment, and has a small decrease in strength.

[0007]

In order to solve the above-mentioned problems, the present inventor has studied a glass fiber composition which enables stable spinning of glass fibers for a long period of time and is capable of completing acid treatment in a short period of time. . As a result, T was added to the component of borosilicate glass fiber.
These problems were solved by investigating the composition in which a new component was added mainly to iO ₂ .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The composition of the glass fiber of the present invention is Si
_{O 2 50-60wt%, Al 2 O} 3 10-20wt
_{%, B 2 O 3 20-30wt%} , CaO 0.5-
5 wt%, MgO 0-4 wt%, Li ₂ O + Na ₂ O
+ K ₂ O 0-0.5% and TiO ₂ 0.5-5 wt%. Li ₂ O is added in an amount of 0-0.3 wt%. TiO ₂ is added to lower the melting temperature and improve the strength of the porous glass fiber, and Li ₂ O is added to homogenize the phase-separated state, reduce the pore diameter of the porous glass fiber, and reduce variations. . Na ₂ O + K ₂ O is an unavoidable component contained in the raw material. In addition to the above components, components such as ZrO ₂ , F ₂ and SO ₃ can be contained up to 3 wt% to the extent that the characteristics of the glass are not impaired. Since the composition is limited in this way, 1) the spinning temperature is low, the spinnability is good, and the fiber diameter can be made small, so that the acid treatment is completed in a short time. 2) Since the acid treatment time is short, the SiO ₂ skeleton in the glass is less destroyed. 3) The phase-separated state is stable and a sharp pore size distribution can be obtained. The reason for limiting the glass composition in the present invention is that SiO ₂
If it is less than 50% by weight, the strength of the porous fiber is greatly reduced, and if it is more than 60% by weight, the viscosity of the molten glass becomes too high and spinning becomes difficult. If Al ₂ O ₃ is less than 10 wt%, phase separation is likely to occur and acid treatment tends to increase pores and reduce the specific surface area. On the other hand, if it is 20 wt% or more, the liquidus temperature rises and the spinnability deteriorates. B ₂ O ₃ is a component used as a fluxing agent to lower the viscosity and facilitate melting, but if it is 20 wt% or less, the viscosity increases, and if it is 30 wt% or more, elution due to acid treatment increases and the strength of the porous glass fiber decreases. Grows larger. When CaO is 5 wt% or more and MgO is 4 wt% or more, the strength is largely reduced by the acid treatment. Li ₂ O + Na ₂ O + K ₂ O is 0.5 wt%, L
If i2O is 0.3 wt% or more, the pore size becomes too large.

The raw material glass for producing the glass fiber of this composition is excellent in meltability and spinnability, and has low acid resistance. Therefore, when the glass fiber is treated with an aqueous solution of an acid, mainly SiO ₂ and TiO ₂ remain porous. A high quality glass fiber is obtained. The desired component and specific surface area of the treated glass fiber can be obtained by adjusting the glass composition, the acid treatment time, the treatment temperature, the acid concentration and the like according to the purpose of use.
The content of porous glass fiber is SiO ₂ 93-98 wt%
, TiO ₂ 0.5-3 wt%, it is possible to obtain a porous glass fiber suitable for applications requiring heat resistance. Further, in the field of utilizing the porous nature of glass fiber, SiO ₂ 90-97 wt%, Ti
It is preferable to use porous glass fibers having a composition of O ₂ 0.5-3 wt%. Further, a product using the glass fiber of the present invention includes a fiber bundle, a yarn, or a processed cloth,
There are various forms such as paper, but any form can be used for acid treatment.

As the type of acid required for the acid treatment, nitric acid, which has a small decrease in tensile strength, is suitable, and then sulfuric acid, hydrochloric acid, etc. are suitable. Suitable treatment time varies depending on the composition of glass fiber, kind of acid, concentration, treatment temperature, etc.
If this glass fiber is treated at a temperature of 70 ° C. using wt% nitric acid, the porous glass fiber containing 90 wt% or more of SiO ₂ of the present invention is obtained in about 10-20 minutes. However, if the purpose of using the porous glass fiber is adsorption of gas, it is desirable that the concentration of acid is low in order to reduce the diameter of the pores and increase the specific surface area, and for applications requiring heat resistance,
In some cases, it is desirable that the acid-soluble component is removed as much as possible, and that the acid concentration is high, and the concentration is not limited to the above concentration, and the test is repeatedly determined depending on the application. The type of acid used is not limited to one type of acid, and may be a mixture of two or more types of acids, which can be appropriately selected from those capable of efficiently eluting soluble components from the glass of the present invention.

After the acid-treated fiber is thoroughly washed, when it is used as a porous glass fiber, it is about 100-250.
It is dried at a temperature of about ℃. This porous fiber preferably has a specific surface area of 150 m ² / gr-500 m ² / gr. This is because when the specific surface area is 150 m ² / gr or less, the adsorptivity is small and the cost performance is poor,
When it is 500 m ² / gr or more, the strength is lowered and the use is limited. However, it goes without saying that even the range of more than this range can be used in the field where the strength as a fiber is not required. When the strength of the fiber is insufficient or when it is used for applications requiring heat resistance of 650 ° C or higher, 600
It is necessary to heat at −800 ° C. to improve the strength and to remove the expected heat shrinkage in advance. Temperature 6
If the temperature is 00 ° C or lower, the heating effect is small, and if the temperature is 800 ° C or higher, the porosity is sacrificed but the strength is increased. The upper limit temperature in this case depends on the chemical composition of the porous fiber to be heated, but is lower than the temperature at which deformation occurs during heating of the fiber.
The dried fiber contains SiO ₂ and TiO ₂ and is bonded to each other to form a network, and the time required for elution is short and the network of SiO ₂ and TiO ₂ is short.
It has a tensile strength due to the fact that it is not easily broken and the weight loss due to elution is small, and the porous fiber obtained by acid-treating the conventional E glass fiber as the porous fiber cannot be used due to insufficient strength. Exchanger, ion separator,
It can be used as an adsorbent, a gas-liquid separator, a catalyst and the like.

[0012]

【Example】

<Example 1> SiO ₂ 51.8 wt%, Al ₂ O ₃
13.8 wt%, B ₂ O ₃ 26 wt%, CaO
3.6 wt%, MgO 2.4 wt%, Li ₂ O 0.
15 wt%, Na ₂ O 0.15 wt%, K ₂ O 0.
A glass fiber yarn made of 200 glass fibers of the present invention having a composition of 1 wt% and TiO ₂ 2.0 wt% and an average fiber diameter of 7 μm was used, and a cloth of warp 60/25 mm and weft 58/25 mm was used. Weaved and cut into 10 cm squares, 50 gr of 10 wt% hydrochloric acid at a temperature of 70 ° C.
After being immersed in the glass for 15 minutes, it was washed with water and heated at 250 ° C. for 30 minutes to remove water inside the porous glass fiber.

Comparative Example 1 The composition and physical properties of the porous glass fiber obtained in Table 1 were compared with the physical properties of a typical porous glass, Corning # 7930. Specific surface area is B
It was measured by the ET method. Heat resistance is obtained by putting porous glass fiber obtained by acid treatment into an alumina crucible and
The state of fibers was compared by heating at 350 ° C. for 30 minutes. The composition is the result of measurement by fluorescent X-ray analysis.

<Example 2> and <Example 3><Example2> used sulfuric acid having a concentration of 10 wt% instead of hydrochloric acid, and <Example 3> used nitric acid having a concentration of 10 wt%. Acid treatment was performed under the same conditions as in Example 1 except for the above. The treatment time is the time until there is almost no change in the weight of the raw glass fiber, and the heat resistance and glass composition of the obtained fiber are shown in Table 1.
Shown in

Comparative Example 2 Using a glass fiber yarn made of 200 E glass fibers having an average fiber diameter of 7 μm, weaving a cloth of 60 warps / 25 mm and 58 wefts / 25 mm, and cutting it into 10 cm squares. Made into SiO _{2 in} the fiber
Of 50% of hydrochloric acid of 10 wt% at a temperature of 70 ° C. so that the content of 95 wt.
After soaking for 0 minute, it was washed with water and heated at 250 ° C. for 30 minutes to remove the water content inside the porous glass fiber. The same test as in Example 1 was conducted and the results are shown in Table 1.

[0016]

The porous glass fiber according to the present invention has the following effects. Since melt-spinning is easy, it is possible to stably produce a fiber having a small diameter that requires a short time for acid treatment. It is possible to elute the acid-soluble component in the glass fiber in a short time without performing a reheat treatment for phase separation vitrification that facilitates acid elution. As a result, SiO in the glass fiber
Of ₂ were mainly skeletal useless - because the character is small, SiO ₂
Probably due to the synergistic effect with the strong TiO ₂ skeleton, the decrease in strength is less than that of the fiber before treatment.

Alternatively, as shown in the examples of the present invention, the porous glass fiber having excellent heat resistance is heated to 1350 ° C., but the fiber is still flexible and is not suitable for use in applications requiring heat resistance. It is possible. Further, as can be seen from the examples, the strength of the cloth made of porous fiber is sufficient for applications such as a filter, and it is also used for adsorption of a specific gas in a gas, removal of foreign matters in high-temperature molten aluminum, etc. I can.

[0018]

[Table 1]

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area C03C 3/06

Claims (3)

[Claims] 1. A porous glass fiber produced by eluting a component easily soluble in an acid in the glass fiber, wherein at least SiO _{2 is used.}
90.0-98.0wt%, TiO ₂ 0.5-3.
A porous glass fiber having a content of 0 wt%. 2. A porous glass fiber according to claim 1, which is 600-8.
Glass fiber obtained by heating to 00 ° C. 3. A specific surface area of 150 m ² / gr-500 m ²
The porous glass fiber according to claim 1, which is / gr.