KR20110048265A - Composition of Glass Fiber for Improving Thermal Conductivity - Google Patents

Abstract

PURPOSE: A glass fiber composition for improving the thermal conductivity is provided to obtain an electric insulating property and a heat emitting property by adding an aluminum oxide and a magnesium oxide to gypsum and boron. CONSTITUTION: A glass fiber composition for improving the thermal conductivity includes silica, an aluminum oxide, gypsum, a magnesium oxide, an alkaline oxide, ferric oxide, and boron. The alkaline oxide is one selected from a group including lithium oxide, sodium oxide, and potassium oxide. The glass fiber composition further includes at least one selected from a group including diamond, silicon carbide, crystalline silica, aluminum nitride, boron nitride, and beryllium oxide.

Description

Composition of Glass Fiber for Improving Thermal Conductivity

The present invention relates to a glass fiber composition capable of improving thermal conductivity, and more particularly, to a glass fiber composition for preparing a glass fiber capable of emitting a certain level of heat while maintaining electrical insulation.

Generally, glass fiber refers to an amorphous artificial mineral inorganic fiber prepared by fusing a raw material at a high temperature to form a filament of 2 to 30 μm. Glass fiber has the property of having heat resistance, chemical resistance, electrical insulation, and heat insulation while at the same time having no absorptivity and small stretchability. Glass fibers having such characteristics can be used in the form of sheets, webs or whiskers for use in refractory fabrics or electrical insulation materials or as building materials for thermal insulation, sound-absorbing sound insulation or air filtration.

Prior art relating to compositions for the preparation of glass fibers is disclosed in Patent Publication No. 2005-0104728 “Biodegradable Glass Fiber Compositions”. The prior art relates to a glass fiber composition having excellent biodegradability and water resistance, which is 61 to 66 wt% of silicon dioxide (SiO ₂ ), 0.1 to 2.5 wt% of aluminum oxide (Al ₂ O ₃ ), and barium oxide (B ₂ O ₃ 4 Disclosed is a glass fiber composition consisting of ˜8 wt%, Na ₂ O + K ₂ O 12-17 wt%, and CaO + MgO 9-15 wt%.

Known glass fibers or glass fibers disclosed in the prior art are produced to have thermal insulation along with other general physical properties. However, fiberglass needs to be made to emit more than a certain level of heat, depending on the application. For example, when used as an intermediate material for reinforcement or insulation in a printed circuit board, the glass fiber is advantageously made to effectively release heat generated from the substrate to the outside.

The present invention is to propose a glass fiber composition for the production of glass fibers for use as a material that needs heat radiation as described above has the following object.

It is an object of the present invention to provide a glass fiber composition for the production of glass fibers having both electrical heat transfer and heat dissipation characteristics.

According to a suitable embodiment of the present invention, the composition for the production of glass fibers comprises silica (SiO ₂ ) 56 to 72 wt%; Aluminum oxide (Al ₂ O ₃ ) 8-22 wt%; Gypsum (CaO) 6-8 wt%; Magnesium oxide (MgO) 3.5 to 5 wt%; 0.3 to 0.6 wt% of an alkali oxide (R 2 O); 0.010 to 0.02 wt% ferric oxide, and boron (B ₂ O ₃ ) to be 100 wt% in total, wherein the alkali oxide (R ₂ O) is lithium oxide (Li ₂ O), sodium oxide (Na ₂ O) And at least one selected from the group consisting of potassium oxide (K ₂ O).

According to another suitable embodiment of the present invention, the amount of aluminum oxide is at least 15 wt%.

According to another suitable embodiment of the invention, the weight ratio of silica to gypsum is at least 9: 1.

According to another suitable embodiment of the present invention, there is provided a glass fiber sheet which can be applied to a printed circuit board or a luminaire.

The glass fiber produced by the composition according to the present invention has the advantage that it can be used as a reinforcement for the support of a printed circuit board or a lighting fixture that is made in sheet form, web form or whisker form. Along with this, the glass fiber composition according to the present invention has the advantage of having electrical insulation required according to the use with heat dissipation.

Hereinafter, the present invention will be described in detail with reference to the embodiments, but the embodiments presented are illustrative for clarity of understanding and are not intended to limit the scope of the invention.

The composition for the production of glass fibers according to the invention comprises alkali oxides (R2O) based on silica, gypsum and boron components and comprises an appropriate amount of aluminum oxide and magnesium oxide to increase the thermal conductivity.

Specifically, the composition according to the present invention comprises silica (SiO ₂ ) 56 to 72 wt%; Aluminum oxide (Al ₂ O ₃ ) 8-22 wt%; Gypsum (CaO) 6-8 wt%; Magnesium oxide (MgO) 3.5 to 5 wt%; 0.3 to 0.6 wt% of an alkali oxide (R 2 O); Ferric oxide 0.010 to 0.02 wt: and boron (B ₂ O ₃ ) to be 100 wt% in total and the alkali oxide (R ₂ O) is lithium oxide (Li ₂ O), sodium oxide (Na ₂ O) and At least one selected from the group consisting of potassium oxide (K ₂ O).

The composition of glass fibers basically comprises silica to form and stabilize a network of glass compositions, gypsum to reduce viscosity while having a filling function, and boric acid to impart elasticity to the manufactured glass fibers while controlling the melting point. The alkali oxide having the function of a melting agent may be at least one selected from the group consisting of lithium oxide, sodium oxide and potassium oxide, but may preferably consist of at least two mixtures.

Thermal conductivity in the composition according to the invention can be improved in two ways. Specifically, it can be controlled by the relative weight of silica and gypsum and the thermal conductivity can be improved by controlling the amount of magnesium oxide or aluminum oxide.

The thermal conductivity of gypsum is about 0.8 W / mK and the thermal conductivity of crystalline silicon dioxide is about 1.3 W / mK. Therefore, except for the other components, the smaller the amount of gypsum in order to improve the thermal conductivity is advantageous. On the other hand, gypsum can reduce the viscosity, so it should be an amount that can maintain the viscosity at a constant level during the melting process. According to the invention, the ratio of silicon dioxide: gypsum may be from 7: 1 to 12: 1 but preferably at least 9: 1.

Another way to control thermal conductivity is to increase the amount of aluminum oxide and magnesium oxide. In general, the thermal conductivity of aluminum oxide is 30 to 35 W / mK, and the thermal conductivity of magnesium oxide is about 42 W / mK. As such, aluminum oxide and magnesium oxide are advantageously included in the composition because they have a large value of thermal conductivity compared to other components of the composition. On the other hand, aluminum oxide has the function of a network former and magnesium oxide has a function of controlling the liquidus temperature, so it needs to be adjusted in an appropriate amount. According to the invention aluminum oxide may be included in the composition in an amount of 8 to 22 wt%, preferably 15 to 22 wt% and magnesium oxide may be included in the composition at 3 to 5 wt%, preferably 4.5 to 5 wt%. .

Since the second iron oxide corresponds to the content of impurities contained in the composition, it is advantageous to have a small value depending on the purity of the raw material.

Glass fibers prepared from the composition as described above may have a thermal conductivity of 0.85 W / mK or more higher than 0.76 W / mK corresponding to the thermal conductivity of other known glass.

In addition to the composition according to the invention, small amounts of diamond, silicon carbide (SiC), crystalline silica (SiO ₂ ), aluminum nitride (AlN), boron nitride (BN), silicic acid (Si ₃ N ₄ ) and beryllium oxide (BeO) At least one substance selected from the group consisting of) may be added. Such materials may be added in the form of fine particles or fine powder and dispersed in the composition. Alternatively, the prepared glass fiber may be added by a method of infiltrating into the glass fiber in the form of fine particles or fine powder in a subsequent process. The amount of the substance added may be 0.1 to 10.0 wt% based on the total composition.

Hereinafter, an embodiment of the composition according to the present invention will be described.

Example

Using the following raw materials to form a composition for the production of glass fibers.

Table 1: Raw Material Mixing Ratios of Glass Fiber Compositions

Raw material Example 1 Example 2 Example 3  Input (kg) wt% input wt% input wt% Limestone 250 3.8 250 3.8 250 3.8 Gray stone 1200 18.5 1200 18.5 1200 18.5 Na ₂ CO ₃ 30 0.5 30 0.5 30 0.5 Na ₂ SO ₄ 20 0.3 20 0.3 20 0.3 SiO ₂ 3500 53.9 3800 58.5 4200 64.6 Al ₂ O ₃ 1250 19.2 950 14.6 550 8.5 MgO 250 3.8 250 3.8 250 3.8 Sum 6500 100 6500 100 6500 100

The components of the melt formed from the raw materials are as follows.

Table 2: Composition ratio of melt

ingredient Example 1 Example 2 Example 3 SiO ₂ 58.608 63.541 64.118 Al ₂ O ₃ 20.610 15.677 15.100 CaO 7.585 7.585 7.585 MgO 4.639 4.639 4.639 B ₂ O ₃ 7.975 7.975 7.975 R2O 0.473 0.473 0.473 F ₂ O ₃ 0.016 0.016 0.016

The raw materials may be mixed in a predetermined ratio, introduced into a melting furnace, and formed into a melt at a high temperature of 1400 ° C. or more to form a filament, or a plurality of filaments may be gathered into strands. The manufacturing process of such glass fibers can be made according to methods known in the art.

Glass fibers made from the composition may be prepared in various forms such as sheets, mats, or whiskers to be used as heat dissipating sheets or pads of printed circuit boards or lighting fixtures.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention . The invention is not limited by these variations and modifications, but is only limited by the scope of the appended claims.

Claims (5)

In the composition for the production of glass fibers, Silica (SiO ₂ ) 56-72 wt%; Aluminum oxide (Al ₂ O ₃ ) 8-22 wt%; Gypsum (CaO) 6-8 wt%; Magnesium oxide (MgO) 3.5 to 5 wt%; 0.3 to 0.6 wt% of an alkali oxide (R 2 O); 0.010 to 0.02 wt% ferric oxide, and boron (B ₂ O ₃ ) to be 100 wt% in total, wherein the alkali oxide (R ₂ O) is lithium oxide (Li ₂ O), sodium oxide (Na ₂ O) And at least one selected from the group consisting of potassium oxide (K ₂ O). The composition of claim 1 wherein the amount of aluminum oxide is at least 15 wt%. The composition of claim 1 wherein the weight ratio of silica to gypsum is at least 9: 1. The group of claim 1 wherein the group consists of diamond, silicon carbide (SiC), crystalline silica (SiO ₂ ), aluminum nitride (AlN), boron nitride (BN), silicic acid (Si ₃ N ₄ ), and beryllium oxide (BeO). Composition for the preparation of glass fibers further comprising at least one material selected from the amount of 0.1 to 10.0 wt%. A glass fiber molded article in the form of a fiber, sheet, web or whisker made from the composition according to claim 1.