JP2743214B2 - Fiber filler material and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fiber filler material mainly composed of alumina and silica.

[Prior art] Fibers whose main components are alumina and silica are generally used as high-temperature insulation materials because of their high heat resistance. Recently, however, they have been used as reinforcing materials by mixing them with a matrix such as metal or plastic. It is used as a means for achieving stability of hardness and dimensions.

Such fibers, when amorphous, have an alumina content of about 40-65% by weight with the balance being silica. The crystalline one has an alumina content of about 60-95% by weight,
The balance consists of silica. Each fiber has the above-described composition as a basic composition, and it is also known to add tens of percent to several percent of subcomponents such as chromium oxide, zirconium oxide, and boron oxide. These are improvements in heat resistance and ease of fiberization.

These fibers are classified into continuous fibers and short fibers when classified by fiber length. Continuous fibers are wound on bobbins, and short fibers are aggregates of about 50 to 100 mm.
Each is handled.

When these fibers are used as a filler material, continuous fibers are cut short and used. The short fiber, as it is,
Cut and use shorter.

[Problems to be Solved by the Invention] When the above-mentioned fiber is cut, the cut area increases accordingly,
As a result, the surface area of all fibers increases.

This increase in surface area becomes more pronounced as the fibers are cut into smaller pieces. For example, 3μm in diameter and 100mm in length
When the fibers are cut to 50 μm, the surface area increases by 3%,
When cut to 10 μm, the surface area increases by 15% and 3 μm
When cut into pieces, the surface area increases by as much as 50%.

Originally, alumina siliceous fibers have a smaller fiber diameter and a larger specific surface area than glass fibers or the like.

In addition, the new surface created by cutting the alumina siliceous fibers is very active. An active surface is highly reactive and tends to react with and adsorb other substances. Due to such properties, there is a risk that the alumina siliceous fiber constantly adsorbs impurities during the steps such as cutting and classification.

When such a fiber is used as a filler material, impurities adhered or adsorbed to the fiber (particularly, elements which are universally present as impurities are Na and Fe) affect a matrix such as a resin. In particular, impurities such as Na and Cl are easily eluted in water present in the matrix.

Soluble components eluted in the matrix may not be a problem, but may be very problematic.
For example, when a fiber filler material is used as a semiconductor encapsulating material, the presence of a trace amount of alkali metal is particularly disliked. This is because the characteristics of the semiconductor are impaired. Therefore, a fiber filler material having a large amount of alkali elution into the matrix resin cannot be used as a semiconductor sealing material.

An object of the present invention is to provide a method for secondary processing of a short fiber or a continuous fiber into a short fiber filler material, in which impurities adhered to fibers mainly during secondary processing are not eluted into a matrix resin. .

Another object of the present invention is to provide a fiber filler material having a small amount of alkali elution into a matrix resin.

[Means for Solving the Problems] According to the invention of claim 1, the alumina content is 40 to 95% by weight.
In a method for producing an amorphous or polycrystalline fiber filler material in which the remaining main component is composed of silica, a continuous fiber or a short fiber is cut so that the average fiber length becomes 200 μm or less, and a cut product thereof. Is subjected to an acid treatment and a heat treatment. The heat treatment temperature is preferably from room temperature to 1000 ° C.

The invention according to claim 2 has an alumina content of 40 to 95%.
In an amorphous or polycrystalline fiber filler material whose main component is silica in weight%, the average fiber length is 200%.
μm or less, the fiber is acid-treated, distilled water was added to the fiber filler at a ratio of 8 gr of distilled water to 1 gr of the fiber filler and heated at 95 ° C. for 20 hours.
A fiber filler material characterized in that the concentration of Na ⁺ ions is 0 to 5 ppm or less.

[Effect] The acid treatment suppresses elution of fiber impurities into water.

In the present invention, the acid used for the acid treatment may be any of an organic acid and an inorganic acid. Such inorganic acids include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid and the like.
Organic acids include acetic acid, formic acid, oxalic acid, citric acid, lactic acid and the like. Also, mixtures of these acids can be used.

The acid concentration, treatment temperature, and treatment time are arbitrary. As seen in ordinary chemical reactions, the acid concentration and the treatment temperature are proportional to the reaction rate. If processing is to be performed in a short time, the temperature may be increased and the concentration may be increased.

[Experimental Example] Hereinafter, an experimental example will be described in detail.

First, amorphous short fibers were manufactured. Table 1 shows the impurity analysis values of the raw materials used.

In Table 1, ACL-27 and CAH-501 are extremely high-purity alumina raw materials. According to the chemical analysis values, the contents of Fe and Na are particularly low. On the other hand, A-H is alumina which is generally used in a large amount by the Bayer method,
Na is much more than that of high purity. P-3 is a raw material of high-purity silica. Flattery sand is a natural silica raw material, which has few impurities as a natural raw material,
Impurities are more noticeable than high-purity raw materials.

High-purity alumina and high-purity silica shown in Table 1 were blended at a predetermined ratio. The formulation was melted in an electric arc furnace and the melt was directed as a thin stream outside the furnace. High-speed air was applied to the fine stream to form fibers.

Table 2 shows the target composition. Comparative Example 1 in Table 2
In a, the alumina raw material is ACL-27 and the silica raw material is P-
It was set to 3. In Comparative Example 3-a, the alumina raw material was CAH-501, and the silica raw material was P-3. In Comparative Example 2-a, alumina raw material was used by mixing ACL-27 and CAH-501 by 50% each, and silica raw material was designated as P-3. In Comparative Example 4-a, the alumina raw material was used as AH, and the silica raw material was used as flattery sand.

The fibers thus obtained were short fibers having an average fiber length of 50-100 mm. Table 3 shows the chemical analysis values of the impurities in the obtained short fibers.

According to Table 3, the amount of impurities in each of the short fibers was larger than that expected from the composition of the raw materials. In particular, the increase of Na and Fe is remarkable. This is because impurities were mixed during the manufacturing process.

The short fibers thus obtained were ground in a general-purpose ball mill using a lining and balls made of alumina. Next, the pulverized material (untreated fiber filler material) was subjected to an air classifier to separate the non-fiber material (shot) and the unmilled fiber. Table 3 shows the impurity analysis values of the classified untreated fiber filler material, and Table 4 shows general physical properties.

In Table 3, Comparative Examples 1-b, 2-b, 3-b, 4
-B shows an untreated fiber filler material. The original short fibers correspond to Comparative Examples 1-a, 2-a, 3-a, and 4-a, respectively. According to these analysis values, the increase in Fe and Na is particularly remarkable by the pulverization treatment and the classification treatment.

Next, the untreated fiber filler material was acid-treated with hydrochloric acid. First, completely immerse the untreated fiber filler material in 3N hydrochloric acid,
The reaction was performed at room temperature for 16 hours. The treated fiber filler material thus obtained was separated from hydrochloric acid and washed well with pure water. 600 ° C of the washed treated fiber filler material in an electric furnace
For 1 hour.

The analytical values of the acid-treated fiber filler material are shown in Table 3. Examples 1-b, 2-b, 3-b, and 4-b are acid-treated fiber filler materials, and each of Comparative Examples 1 before being subjected to the acid treatment.
-B, 2-b, 3-b and 4-b. According to the analysis values, although Fe was greatly reduced, Na was hardly reduced. The same applies to K.

Next, extraction water characteristics were tested for each of the staple fiber, the untreated fiber filler material obtained by cutting the staple fiber before the acid treatment, and the treated fiber filler material obtained by acid-treating the untreated fiber filler material.

The test was performed as follows. First, 8 gr of each fiber was weighed, and each was placed in a polyethylene container together with 80 gr of distilled water. Next, the container was put in a thermostat at 95 ° C. After a lapse of 20 hours, the container was taken out of the thermostat and cooled to room temperature.
Acidity The supernatant liquid in the ^{vessel, Na +, K +, Cl} - concentration and electric conductivity were measured in. Table 5 shows the results.

According to Table 5, the Na ⁺ elution concentration is higher for the cut fibers than for the short fibers, and the acid-treated fibers are less than the cut fibers before the acid treatment, and have an approximately equivalent relationship to the short fibers. . That is, Comparative Examples 1-a, 2-a, 3-a, 4-a
The number of cut fibers before acid treatment is larger than that of fibers before acid treatment.
And the electric conductivity shows the same tendency. This seems to be due to the influence of impurities mixed in by processing such as cutting. However, Comparative Examples 1-b, 2-b, 3-b, 4-b
In comparison with Examples 1-c, 2-c, 3-c, and 4-c, the examples each have a lower Na ⁺ concentration. This is considered to be the effect of the acid treatment.

On the other hand, Na ^{+ of} Experimental Examples 1-c, 2-c, 3-c and 4-c
Concentrations show almost the same tendency as Comparative Examples 1-a, 2-a, 3-a and 4-a. However, the Na ⁺ concentration was determined in Comparative Example 4.
Experimental Example 4-c is less than -a. The electrical conductivity shows almost the same tendency. That is, it appears that Na in the fiber is apparently reduced by the acid treatment. But,
As described above, in Table 2, Comparative Examples 1-b, 2-b, 3
-B and 4-b did not mean that the Na ⁺ concentration was reduced by the acid treatment. This indicates that the acid treatment did not reduce the impurities in the fiber filler material, but changed to a structure that was difficult to elute with water.

The mechanism by which the properties of the fiber filler material are changed by the acid treatment as described above is unknown, but the following reaction is considered as one hypothesis. That is, when the untreated fiber filler material is immersed in an acid, Al ³⁺ is selectively eluted from the surface of the untreated fiber filler material into the acid, leaving a gel layer of SiO ₂ on the surface. This SiO ₂ gel layer becomes a stable layer by drying or heat treatment, and prevents the elution of Na ⁺ .

In the method of the present invention, the amount of Na ⁺ eluted is affected by the temperature of drying or heat treatment after acid treatment. In general, the higher the temperature, the less Na ⁺ is eluted. The range is from room temperature to 1000 ℃
Can be set arbitrarily, but the range of 100 to 800 ° C. is the easiest to handle and the efficiency is good. If the temperature exceeds 1000 ° C., the strength of the filler material decreases.

Further, the treatment for fixing the water-soluble component in the fiber by the acid treatment is not limited to the amorphous fiber, and is effective even when the silica content is about 5%.

When the fiber filler material of the present invention is used as a filler material of a semiconductor sealing resin, the elution concentration of Na ⁺ in water is desirably 5 ppm or less according to the test method. If it exceeds 5 ppm, it is inappropriate.

Various methods can be applied to the analysis of trace components.
For example, the determination of Na ⁺ and K ^{+ in} the extraction water shown in Table 5 was carried out by flame photometry. Cl ^- Quantification spectrophotometric method was used for.

[Effect of the Invention] Water-soluble impurities mixed into the fiber filler material or adhered to the surface of the filler material are not eluted into water by the acid treatment.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 23/31 // D06M 101: 00 (72) Inventor Shigeo Endo 4-4 Nihonbashi Hisamatsucho, Chuo-ku, Tokyo Itoshige Building Toshiba Monoflux stock Inside the company (72) Inventor Kimio Hirata 4-4 Nihonbashi Hisamatsucho, Chuo-ku, Tokyo Itoishi Building Toshiba Monoflux Co., Ltd. (72) Inventor Yu Shinbo 30 Soya, Hadano-shi, Kanagawa Toshiba Ceramics Co., Ltd. In-house (72) Inventor Koichi Shiraishi 30 Soya, Hadano-shi, Kanagawa Toshiba Ceramics, Inc. Central Research Laboratory (56) References JP-A-62-223235 (JP, A) JP-B-57-16856 (JP, B2)

Claims (2)

(57) [Claims] 1. A method for producing an amorphous or polycrystalline fiber filler material comprising 40 to 95% by weight of alumina and the remaining major component comprising silica, wherein continuous fibers or short fibers are average fibers. A method for producing a fiber filler material, comprising cutting the length to be 200 μm or less, acid-treating the cut pieces, and heat-treating the cut pieces. 2. An amorphous or polycrystalline fiber filler material having an alumina content of 40 to 95% by weight and a residual main component of silica, wherein the average fiber length is 200 μm or less, and Acid-treated, distilled water is added to the fiber filler material at a rate of 8 gr of distilled water to 1 gr of the fiber filler material, and when heated at 95 ° C. for 20 hours, the concentration of Na ⁺ ions in the distilled water is 0 to 5 ppm or less. Fiber filler material characterized by becoming.