JPH0369573A - Carbon fiber heat insulating material - Google Patents

Abstract

PURPOSE:To form the carbon fiber heat insulating material having densities of a wide range with fewer stages for working by subjecting a mixture composed of carbon fibers of a pitch system and an expandable resin to expansion molding, then to calcination. CONSTITUTION:This carbon fiber heat insulating material is formed by subjecting the mixture composed of the carbon fibers of the pitch system and the expandable resin to the expansion molding then to the calcination. Compounding of other heat resistant fillers in addition to the carbon fibers of the pitch system for the purposes of providing improvement in the strength and dimensional stability of the heat insulating material, improvement in expandability, improvement in packing workability, etc., is possible as well. Such heat resistant fillers are exemplified by, for example, carbon black, graphite, coke, pitch, alumina, inorg. or org. fiber whiskers, polyacrylonitrile carbon fibers, etc. The expandable resin may be either of powder or liquid type if the resin has good expandability and has the relatively high carbonization rate at the time of high-temp. calcination.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to pitch-based carbon fiber (hereinafter abbreviated as pitch-based CF) alone or to pitch-based CF with carbon black,
This relates to a carbon fiber insulation material obtained by dispersing and mixing a mixture obtained by mixing at least one type of heat-resistant filler selected from Gratubite, etc. with a foamable resin, and heating and foaming the mixture, which is an inexpensive and simple method. The present invention relates to a heat insulating material that can be easily manufactured, has a wide range of bulk densities, and has a complex shape, and can be used in a wide range of applications in an inert atmosphere.

(Prior technology) In an inert atmosphere such as nitrogen, argon, vacuum, etc. and at high temperature (1
Carbon fiber insulation materials are widely used in many furnaces used at temperatures above 000°C. Such carbon fiber heat insulating materials are produced in two ways depending on the required heat insulating properties, operating temperature, atmosphere, shape, etc. First, most of them are made from felt, impregnated with a resin with a high carbonization rate such as phenol resin, formed into the desired shape such as a flat plate or cylinder, and then fired at around 2000℃. . The heat insulating material obtained in this way has the advantages of having excellent heat insulating properties, being able to raise and lower the temperature in a short time, being lightweight, and being easy to process. One of the major obstacles to expanding the demand for carbon fiber insulation is that it occupies a large proportion of the cost and is consequently expensive.

On the other hand, another method is known in which relatively inexpensive carbon fiber gord or chopped fiber is impregnated or mixed with phenol resin etc. in the same manner as the raw material, filled into a predetermined mold, formed, and then fired. There is. In this case about 0
．． Insulating materials having a wide range of bulk densities from about 2 to 0.6 gr/cm3 can be manufactured, and materials of various shapes can be manufactured relatively easily.

However, carbon fiber milled or chopped fibers can be produced by wet or dry methods of impregnation or mixing, but because they are relatively bulky, they have to be filled into a mold, or carbon fibers with a density higher than the bulk density of the mixture are required. To make this, it is necessary to pressurize it in some way after filling it. Particularly in the case of the dry method, filling is time-consuming and there are limits to the bulk density of the material that is desired to be produced.

In order to avoid the above-mentioned problems, it is effective to reduce the apparent density of the mixture of carbon fiber and resin by a wet method and fill it into a mold, and in fact, many carbon fibers are commercially produced using this method. However, even with this method, the solvent in the resin must be distilled off under reduced pressure after filling, which increases the number of steps and becomes a factor in the cost of 1~amp.

(Problems to be Solved by the Invention) The present invention uses relatively inexpensive pitch-based CF as a main material, and can easily produce carbon fiber insulation with a wide range of densities with few work steps, and can further reduce costs. The aim is to provide materials.

(Means for Solving the Problems) The present invention provides a carbon fiber insulation material obtained by heating and foam-molding a mixture obtained by mixing pitch-based CF with a foamable resin, and then firing it, or a carbon fiber insulation material other than pitch-based CF. The present invention relates to a carbon fiber insulation material containing a heat insulating filler.

The pisoti-based CF used in the present invention is a relatively inexpensive general-purpose type, and may be produced from either coal-based or petroleum-based pitch. The shape of the fibers can be used without any particular restriction, but milled or chopped fibers are preferred because as the bulk density of the fibers increases, the mixture with the resin becomes bulky and difficult to fill. Depending on the bulk density or shape of the intended heat insulating material, milled fibers (those with a thread length of about 11 m or less are referred to as milled here) or chopped fibers (those with a thread length of about 1 mm or more) are used. All you have to do is make a selection. In addition, considering strength, heat insulation properties, etc., pitch-based CF of each yarn length is
It is also possible and effective to combine them.

In addition, as a heat-resistant filler other than pitch-based CF, PAN
Series CF, carponbrasov, graphite, coke,
pitch, alumina, inorganic or organic fiber whiskers,
Metal fibers or powders improve the strength of insulation materials after firing,
It can be used for the purpose of improving dimensional stability, improving foamability, and improving workability such as filling. The type, shape (thread length, particle size, etc.) of the filler can be selected depending on each of these purposes.

In particular, the weight ratio of the pitch-based CF and these fillers is not particularly limited, but is preferably approximately pitch-based CF:filler=1oo:o to 40:60.

The foamable resin used in the present invention has good foaming properties, and has a foaming property of about 10
Powder or liquid types can be used as long as they have a relatively high carbonization rate when fired at a high temperature of 00 to 200°C.Pitch-based CF and filler can be used depending on the bulk density, shape, etc. of the intended insulation material. It can be selected depending on the shape, amount, etc. Examples include phenol resin, PSP resin, bismaleid resin, petroleum resin, and pitch. In fact, powder-type foamable resins that use novolasoc-type phenolic resin and abbisisobutyronidonyl (AIBN) as a foaming agent are commercially available and common, but the foam molding heating temperature and foaming agent As long as the decomposition temperature is selected and combined, resins other than phenol can be used as the base material. On the other hand, liquid type foamable resins, such as those using fluorine-based foaming agents such as acid-curable water-soluble resols, have advantages such as easy impregnation with pitch-based CF, easy filling workability, and low-temperature foaming. This is advantageous for the purpose of the present invention.

The blending ratio of pitch-based CF and other heat-resistant fillers and foamable resin has a large effect on foamability depending on the shape, bulk density, etc. of the pitch-based CF and other heat-resistant fillers used.
Also, considering the dimensional stability of the foamed molded product after firing, it cannot be absolutely defined, but the weight ratio is generally 30:70 to 7.
0:30, preferably in the range of 60:40 to 40:60.

It is also effective to use an appropriate amount of anti-foaming agent such as a surfactant (-1 to 5% based on the amount of resin for boat fishing) in order to foam uniformly.

(Example) Next, the present invention will be further explained by examples.

In addition, parts and percentages in the examples are based on weight unless otherwise specified.

Example 1 ■ A general-purpose pitch-based CF (trademark "Donna Carbo") made from coal tar manufactured by Donatsuku and Novolanc type foamable phenolic resin (trademark "Sumilight Resin") manufactured by Ludfeicher and Sumitomo Durez ■ are commercially available. mixer (C
F was dispersed and mixed using a round tooth (to avoid cutting it). The mixture was filled into a mold and heated in a dryer at 100 to 120°C for 30 to 60 minutes to obtain a foamed molded product.

150 to 160 to complete foaming and resin curing.
Bost cure was performed at ℃ for 60 minutes.

The molded product obtained above was placed in nitrogen or vacuum for 1
The final carbon fiber insulation material was obtained by firing at a temperature of 000 to 2000°C. The firing method is approximately 800°C to 100°C.
Temperature increase of 1-3°C/min until 0'C, 1000-2000
At 100°C, there was no problem. Table 1 shows the bulk density and foaming ratio of mixtures with various blending ratios of Dona Carbo and Sugorite.

-'D / / / Next, for N116 in Table 1, changes in bulk density and dimensional changes of the insulation material before and after firing, strength and insulation properties of the insulation material after firing (2000℃) are shown in Table 2. .

In addition, those with fikl 6 have a bulk density of 0.28 to 0.64.
It is possible to design within the range of .

／ ／ ／ ／ ／ 0 Example 2 A frugality was added to the formulations of each Dona Capo product number shown below, as well as those containing PAN-based CF and graphite. Operator: Spraying was performed in the same manner as in Example 1.

The results are shown in Table 3.

／ ／ ´ノ／ ／ ／ Next, from the compositions of 1' to 4', the high density before firing was 0.3.
Table 4 shows the physical properties of the carbon fiber thermal insulation properties obtained by making a foam molded product of g/cJA and firing it at 2000°C.

/ / / / / / / ■4 Example 3 Dona Carbo, Freon 113 manufactured by Dainippon Ink & Chemicals @
A water-soluble resol type foamable phenolic resin (trademark "Selfen OG") containing as a foaming agent and para-toluenesulfonic acid as a curing agent were wet-dispersed to form a homogeneous slurry. Fill a mold with the slurry mixture, and
A foamed molded article was obtained by heating in a dryer at .degree. C. for 30 minutes. Furthermore, by post-curing it at 150° C. for 1 hour, a foamed molded product in which the resin was completely cured was obtained.

The final carbon fiber insulation material was obtained by firing the obtained foamed molded product in a vacuum up to 2000°C.

Table 5 shows the bulk density before and after firing, dimensional change after firing, bending strength, and thermal conductivity of various blending ratios.

and F/6 (Effects of the Invention) The carbon fiber insulation material of the present invention not only has good heat insulation properties, but also can be produced with a bulk density and shape suitable for the purpose at a low cost, easily, and without requiring capital investment. Therefore, it can be used for a wide range of purposes.

Claims (3)

[Claims] (1) A carbon fiber insulation material made by foam-molding a mixture of pitch-based carbon fiber and foamable resin and then firing it. (2) The carbon fiber insulation material according to claim 1, comprising a heat-resistant filler other than pitch-based carbon fiber. (3) The heat-resistant filler other than pitch-based carbon fiber is at least one type selected from the group of carbon black, graphite, coke, pitch, alumina, inorganic or organic fiber whiskers, and poly-acrylonitrile-based carbon fiber. The carbon fiber insulation material according to claim 2.