JPH05147975A - Heat resistant glass fiber - Google Patents

Abstract

PURPOSE:To obtain a glass fiber having much more excellent heat resistance than an E glass fiber, capable of being easily produced with the E glass fiber as starting material and similar to the E glass fiber in physical properties except heat resistance. CONSTITUTION:This heat resistant glass fiber has the practically same glass compsn. of borosilicate glass as an E glass fiber as a whole but only the surface layer is made of siliceous glass having >=80wt.% SiO2 content.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has an average glass composition which is substantially the same as that of E-glass fiber, but has a significantly higher heat resistance than E-glass fiber, which is a heat insulating material or a high temperature electrical conductor. The present invention relates to a heat resistant glass fiber suitable for insulating applications.

[0002]

2. Description of the Related Art E-glass fibers are excellent in electrical insulation and corrosion resistance and have high tensile strength, so they are the most common glass fibers for electrical insulation materials, heat insulating materials, and reinforcing fibers for various fiber-reinforced composite materials. It is widely used and most of the long fibers are E glass fibers. A characteristic of the composition is that it is made of borosilicate glass having an alkali metal content of less than 1%, which is called non-alkali glass fiber. E
The softening point of glass fiber is about 845 ° C, but usually about 3
50 ° C. is the upper limit of usable temperature. At a temperature higher than that, in a practical state where some load is applied, it gradually deforms, and it does not recover even after cooling, so that, for example, a mat-like thing becomes an inelastic mass. Ceramic fibers, generally silica-alumina fibers, are used in fields where the E glass fibers lack heat resistance. However, although ceramic fibers have better heat resistance than glass fibers, the temperature at which raw material ceramics are made into fibers is high, and since high technology is required for making them into fibers, they are extremely expensive compared to glass fibers. .. Moreover, it is generally difficult to manufacture continuous fibers. Therefore, in applications in which the heat resistance of E glass fibers is not sufficient but the heat resistance of ceramic fibers is not required, highly heat resistant fibers that can be produced by modifying glass fibers are preferred to ceramic fibers. ..
The heat-resistant fiber that can replace the ceramic fiber is also meaningful from the viewpoint of reducing the amount of the ceramic fiber used, which has recently been pointed out to have an adverse effect on health.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-resistant glass fiber which can be produced from glass fiber as a raw material and has heat resistance close to that of ceramic fiber.

[0004]

The heat-resistant glass fiber successfully provided by the present invention has a glass composition which is substantially the same as that of E glass fiber as a whole, but the surface layer portion has a SiO ₂ content. Of 80% by weight or more, preferably 85% by weight or more, and particularly preferably 90% by weight or more of siliceous glass.

The SiO ₂ content of a typical E glass fiber is about 50 to 63% by weight, and the glass fiber of the present invention has substantially the same average composition as the above E glass fiber, that is, a large amount. Since the SiO ₂ content is not more than 70% by weight, the high siliceous surface layer portion is clearly present in the glass fiber of the present invention like a thin lining layer. However, it does not have a clear two-layer structure in which the composition changes discontinuously from the fiber surface to the core,
Since SiO ₂ content towards the inside from the fiber surface, albeit rapidly but continuously decreases, SiO ₂ in the present invention
When the content is a problem, the region from the fiber surface to the depth of 120Å is called the surface layer. SiO ₂ higher than the fiber core
The high siliceous region, which can be confirmed by analysis to have a content ratio, is several hundred liters to about 100 from the surface layer.
Although it extends to a depth of 0Å, even if you look at this high-silica region as a whole, it is a very narrow "skin" that is very thin in ordinary glass fiber with a fiber diameter of about 10 μm (100,000Å). ..

The components other than SiO ₂ in the surface layer are not particularly limited, but it is desirable that the components having a bad influence on the heat resistance such as B ₂ O ₃ are as small as possible. The approximate content of the main constituent components of the glass fiber according to the present invention is shown below for the surface layer portion and the entire fiber. A general E glass fiber composition is also shown as a reference value. Average value of the entire fiber surface layer fiber E glass fiber SiO ₂ (%) 80 or more 50 to 65 50 to 63 Al ₂ O ₃ (%) small amount 10 to 16 12 to 16 B ₂ O ₃ (%) small amount 2 to 12 8 〜13 CaO + MgO (%) Small amount 14-21 15-20 Na ₂ O + K ₂ O (%) Trace amount Trace amount

[0007]

The reason for the glass fiber of the present invention having a surface layer portion having a SiO ₂ content of 80% by weight or more is that the practical heat resistance limit temperature is significantly higher than that of the E glass fiber, although the reason has not been clarified. For example, a mat made of E glass fiber is about 70
When the temperature exceeds 0 ° C, the fiber rapidly shrinks due to thermal deformation to become a dense lump, which does not function as a fireproof coating material. However, the glass fiber of the present invention can be used for at least 900 ° C for 30 minutes. Endures heating of 1050 ℃
Some even withstand heating for 30 minutes. The glass fiber of the present invention has heat resistance exceeding the level of conventional glass fibers as described above, but in physical properties and chemical properties other than heat resistance, it is expected from the average glass composition of the entire fiber. As described above, it is the same as E glass fiber.

Even if the glass fiber of the present invention has a highly siliceous surface layer and a core layer similar to E-glass, the siliceous surface layer is thick, so that the average glass composition of the entire fiber is also increased. The highly siliceous fiber which is remarkably different from that of the E glass fiber is similar in composition to the so-called silica fiber and is superior in heat resistance to the glass fiber of the present invention, but is not flexible and further has low tensile strength. , Processing such as needle punching is not possible. Further, since it is brittle and easily disintegrates, there is a concern that the dust may adversely affect health, and some of the features of the E glass fiber are lost, which is beyond the scope of the present invention.

The glass fiber of the present invention is prepared by immersing E glass fiber in an aqueous solution of an acid for a suitable time to elute components other than silica, such as alkaline earth metal, alkali metal, alumina and boron oxide, which are present near the fiber surface. After that, it can be easily manufactured simply by washing with water and heating and drying. That is,
Since the E glass that constitutes the raw material fibers is extremely dense and does not allow the acid to permeate, the elution of the glass component by the acid occurs only from the fiber surface, and a part of the component elutes, causing the texture of the surface layer to become loose. For the first time, the acid can penetrate into the inside, so that the acid treatment always forms a clear high siliceous surface layer, and the inside substantially remains the original E glass.

As the acid used for the acid treatment, hydrochloric acid is most suitable, and nitric acid is next suitable. Since the elution rate of the fiber component in the acid treatment varies depending on the concentration of the acid used, the treatment temperature, the presence or absence of stirring, the degree, etc., it is necessary to experimentally determine the preferable treatment time. When hydrochloric acid at about 40 to 70 ° C. is used, the glass fiber of the present invention can be obtained by a dipping treatment for about 30 minutes to several hours.

[0010]

Example E glass fibers manufactured by Nippon Electric Glass Co., Ltd. (long fibers having an average fiber diameter of 9 μm) were immersed in an aqueous hydrochloric acid solution to produce the glass fibers of the present invention. Concentration 9 as hydrochloric acid aqueous solution
%, Temperature 40 ° C, or concentration 12%, temperature 70 ° C
The amount used was 7 times the weight of the raw material fiber. Table 1 shows the glass compositions and heat resistances of fibers and raw fibers obtained by variously changing the immersion time. The composition analysis was carried out by a photoelectron spectroscopic device for the surface layer portion, and the whole fiber was crushed for chemical analysis. "Heat resistance" indicates the judgment result in the following test.

Heat resistance test method: Fiber is put in a crucible and heated in an electric furnace in the range of 900 ° C. to 1050 ° C. at intervals of 50 ° C. to 30 ° C.
Heat for ~ 120 minutes, observe the change in fiber, and judge the heat resistance according to the following criteria. ◎ The suppleness of the fibers is maintained. ○ The suppleness of the fiber is half lost. △ The shape of the fiber remains, but the flexibility is almost lost. ▲ The fibers are fused and deformed. C. All the fibers are melted and the whole sample is one lump.

[0012]

[Table 1]

FIG. 1 shows the results of examining the change in the glass composition from the surface of the glass fiber of the sample according to the above-mentioned production example toward the center at 30 Å intervals.

[0014]

As described above, the glass fiber according to the present invention can be easily produced from E glass fiber as a raw material, and has excellent heat resistance close to that of ceramic fiber. Therefore, it can be used in many fields where ceramic fibers had to be used because of the insufficient heat resistance of conventional E glass fibers, which greatly contributes to the cost reduction of fireproof coating in construction and the improvement of environmental hygiene. Can be done.

[Brief description of drawings]

FIG. 1 E glass fiber treated in the example (sample)
A graph showing the glass composition of the.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hajime Hajime 3-6-10-501 Hirado, Totsuka-ku, Yokohama (72) Inventor Kozo Takimoto 4-1000 3-B Matsumi-cho, Kanagawa-ku, Yokohama

Claims (1)

[Claims] 1. A heat-resistant glass fiber characterized in that the entire fiber has a glass composition substantially the same as that of E glass fiber, but the surface layer portion is made of siliceous glass having a SiO ₂ content of 80% by weight or more. ..