JP2006089373A - Method for producing surface heating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a surface heating material constituted of a formed carbonized material having a light, flexible and porous fiber structure good in processability and reactivity and a strong texture exhibiting high carbon properties by a very simple means at a low cost. <P>SOLUTION: A raw material having a porous structure consisting of an entangled combined body of cellulose single filaments having twisted, wavy and crimped forms is directly subjected to carbonizing/baking treatment by heating without adding a binder in a nonoxidative atmosphere. The entangled binding between the single filaments is strengthened by the carbonization-shrinkage effect generated by the above treatment, and the texture is stabilized and strengthened. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a surface heating material composed of a shaped carbide composed of a single fiber combination.

  Conventionally, a carbonaceous body or carbon body obtained from an organic substance (hereinafter, simply referred to as “carbide”) has a variety of adsorptive, electrical, adiabatic, heat resistance, corrosion resistance, and mechanical characteristics. It is used for various purposes according to the characteristics. However, any of them needs to be in an appropriate form according to the purpose of use. For example, there are various forms of fibrous carbides commonly called “carbon fibers” such as powdered, granular, crushed carbides, long fibers, short fibers, woven fabrics, sheet mats, or strings. In addition, in order to exhibit particularly mechanical characteristics, a composite material obtained by mixing and processing another substance may be used.

  However, as described above, a secondary processing step is required in addition to the carbonization step in order to form a form suitable for various applications. That is, in the case of carbonized granular material, it is necessary to perform pulverization and sizing after carbonization. Further, when carbonized long fibers are used in a cotton form (chopped), it is necessary to shorten the fibers by a cutting (chopping) process. Furthermore, when carbonized continuous fibers are used in the form of woven fabric or string, weaving or braiding must be performed after carbonization. In addition, in these processing steps, carbon fibers that are originally low in elongation and weak in bendability should be woven limited to a relatively flat fabric structure with a low degree of bending. Things such as tissues cannot be processed. Further, when the above-mentioned chopped carbonized short fibers are formed into a sheet or a mat by a paper making method or the like, they are integrally formed by adding a binder (that is, a binder) such as an adhesive to the carbonized material. However, all of the products obtained as a result of this are limited to flat and thin products, and there is a fatal defect that the additive aid remains as a foreign substance that easily deteriorates the inherent characteristics of the carbide.

  As described above, the secondary processing applied depending on the application is very complicated, and in some cases, the carbon characteristics are destroyed, and there is a problem that the cost is unnecessarily increased.

  The present invention has been invented in order to solve many problems inherent in the above-described conventional use of carbides, and is a porous fiber by a simple method and at a low cost. The present invention proposes a method for producing a surface heating material constituted by a structure-hardened shaped carbide that exhibits advanced carbon characteristics in its structure.

  The present invention relates to a method for producing a surface heating material constituted by a shaped carbide composed of a single-fiber bonded body (that is, a bonded material), and a cellulose-based single fiber having torsion, wavy, and crimped forms. A raw material having a porous structure composed of a composite bonded body is prepared, and the above raw material is carbonized by heating it in a non-oxidizing atmosphere without adding a binder, and by the carbonization shrinkage generated by this treatment. The present invention relates to a method for producing a surface heating material characterized by strengthening the intergranular bond between the single fibers and stabilizing and strengthening the structure. In the present invention, it is preferable that the cellulose single fiber not only has torsional, wavy, crimped, and the like in its structure, but also has excellent compatibility and a large external surface area. .

  In the present invention, the cellulose single fiber is preferably a cotton fiber. In addition, since the cotton fiber has a natural twist that twists in a spiral shape, it is not necessary to artificially perform a pretreatment that imparts a wavy or crimped effect. In the present invention, it is preferable that the material of the porous structure is at least one selected from loose fiber (cotton), wrap (rather cotton), sliver (string-shaped shino), and roving (coarse yarn). . In this case, the porous structure material can be made lightweight. Moreover, in this invention, it is preferable that the fiber width of the said cellulose single fiber is 0.01-0.08 mm. In this case, the cellulose single fiber has a very small fiber width and a large surface area. In the present invention, the specific gravity of the shaped carbide is preferably 0.02 or more, and preferably 0.025 or less. Accordingly, the bulk specific gravity is preferably 0.02 to 0.025. In the present invention, the weight of the shaped carbide is preferably 33 to 45% of the raw material of the porous structure.

  Next, the present invention will be described in more detail.

  The first feature of the present invention is that the raw material employed in the present invention is a fiber belonging to the cellulosic system, the external surface area is remarkably large, and it is a single fiber rich in compatibility. It is pre-molded into a desired form by machine operation. This is because all the single fibers are combined and bonded by the inherent properties of all fibers, so there is no need to add a binder or the like. It becomes a porous single fiber bonded body. Next, the raw material is heated and carbonized as it is, but what is important here is that the solid raw material consisting of single fibers produces carbide as a substance as the carbonization reaction proceeds. At the same time, in the form, the entangled material is contracted at a certain rate while maintaining the form of the raw material individual, and the form is maintained until the end. The above phenomenon is the mechanism of the lightweight and porous single fiber bonded body by carbonization employed in the present invention and the strengthening of the structure.

  In general, a raw material solid is easily cured by losing its original toughness due to carbonization, but the raw material solid according to the present invention is shaped after heat treatment in order to employ a single fiber having a small fineness. The change in the apparent degree of hardening of the carbide is very small. This is the same reason that a hard glass plate exhibits flexibility when it turns into a delicate glass fiber. Furthermore, the raw single fibers are remarkably more delicate than conventional carbonized materials (for example, coconut shells and sawdust for producing activated carbon), and the fiber width of the cellulose single fibers employed in the present invention is 0.01-0. It is preferably as small as 08 mm, and its surface area is as large as several hundred times that of the above two types of raw materials. Therefore, the carbide of the single fiber bonded body has extremely high reactivity, and in addition to the carbonization step, the reaction rate is high in the activation treatment performed as necessary, and the advantage is that it proceeds uniformly. There is. This is the second feature of the present invention.

  Next, the raw materials used, carbonization treatment, and characteristics of the obtained shaped carbide in the present invention will be described in further detail.

  Monofilaments used as raw materials are all composed mainly of cellulose, and preferably have a fiber width of about 0.01 to 0.08 mm, and natural fibers and artificial fibers that are regenerated fibers are also raw materials according to the present invention. include. For example, fibers such as cotton, flax, cannabis, jute, ramie, cocoon, cocoon, bamboo candy, and rayon are included. In addition, the consistency of the fiber has a natural twist that twists in a spiral shape in cotton, but the other requires artificially a pretreatment that imparts a wavy and crimped effect. As an example, a desired corrugated or crimped form can be imparted through the raw material short fibers between the heating mold rolls that are rolled up and down relative to each other.

  Next, in order to form a desired porous bonded body using these composite single fibers, equipment normally used in the spinning process is applied as it is. That is, in order to obtain a single fiber loose fiber (cotton-like material), it is obtained by putting raw fiber into a ball breaker machine and unraveling the fiber mass. Moreover, this can be further processed with a cotton-tapping machine to obtain a wrap (rather, cotton). The sliver is obtained by further processing the wrap with a carding machine. Roving (coarse yarn) is produced by adding the minimum sweet twist to the sliver with a kneading machine.

  Firing and carbonization of these raw materials is generally performed by heat treatment at 300 ° C. or higher for about 6 hours in a non-oxidizing atmosphere, and the heat treatment conditions are appropriately adjusted according to the target characteristics. There is a need. Further, the degree of carbonization and the shape change of the object to be processed differ depending on the heat treatment conditions, and adjustment according to the purpose is necessary.

  Next, the characteristics of the shaped carbide constituting the surface heating material according to the present invention obtained by the above method will be described.

  For a long time, carbides have been used in various fields as functional materials, and in particular, there has been a significant leap in the entry into today's new technology. However, the currently used carbides are mainly powders, powders, and crushed bodies, which are still old, and only some applications of carbon fibers that have recently emerged can be seen. Also, in order to adapt the above three types of objects (ie, powder, powder, crushed) and carbon fiber to new applications, most of them have achieved their purpose by making composite materials with other components added. As described above, this may cause a fatal negative surface in addition to the positive surface due to the complicated manufacturing process and contamination with foreign matter.

Next, the characteristics of the shaped carbide constituting the surface heating material according to the present invention are listed in the following items (A) to (D).
(A) The shaped carbide constituting the surface heating material according to the present invention is, when viewed macroscopically, is flexible, lightweight and porous, and its bulk specific gravity is about 0.02 to 0.025. In addition, the flexibility is not much different from that of the raw material (ie, single fiber bonded body). Therefore, this material is “flexible” as a carbide, can be transformed into any form, and has a high degree of freedom of shape change. Much more than carbon fiber processed products, and its weight falls to about 33-45% of the raw material after carbonization. Furthermore, the degree of porosity is reduced by about 20 to 30% compared to the raw material due to carbonization shrinkage, but is about 1/5 compared to the passage resistance of gas and liquid of conventional powdery, granular carbide or woven carbon fiber. The value is as low as 1/15.
(B) When the shaped carbide is viewed microscopically, the carbonized monofilament has a fiber width that is about 30 to 40% lower than that of the raw material, and becomes finer. Therefore, especially in the adsorption performance, the surface area per unit weight is increased, and the adsorption rate and the adsorption saturation amount are remarkably increased as compared with the conventional product.
(C) Describing the electrical characteristics of the above-mentioned shaped carbides, the basics of the electrical characteristics of the use of carbides are determined by the superiority or inferiority of the electrical conductivity. Contact forms a conductive path, and its density affects its properties. However, since the above-mentioned shaped carbides are high in density, are mutually intertwined, and the contact density is large, antistatic (ie, antistatic material), electromagnetic wave shielding (ie, electromagnetic wave shielding material), surface heat generation When applied to (i.e., surface heating material), various electrodes (i.e., electrode materials), electric double capacitors (i.e., materials for electric double capacitors), etc., extremely appropriate effects are exhibited.
(D) The heat insulation property of the above-mentioned shaped carbide will be described as a mechanical design advantage because the porous form doubles its performance and is lightweight. Furthermore, since it is porous and flexible, various kinds of shields (that is, shielding materials) or various kinds of packings (that is, packing materials) have good “familiarity” with devices and are suitable materials.

  In addition, in the various adaptations described above, the shaped carbide constituting the surface heating material according to the present invention is flexible and porous, so that it is very easy and easy to attach and assemble to equipment. For example, for gas phase, liquid phase adsorption or filtration purposes (in other words, as an adsorbent or filter media), simply pack or fill a simple cylindrical element structure. The purpose can be achieved.

  As described above, the degree of freedom with respect to the shape change of the shaped carbide constituting the surface heating material according to the present invention is as convenient as any other.

  According to the present invention, a surface heating material constituted by a structure-hardened shaped carbide that has high workability and reactivity, is lightweight and flexible, and exhibits a high carbon characteristic in a porous fiber structure, is very simple. This method can be manufactured at a low cost.

Example 1
Cotton (made in the United States, fiber width: 0.02 to 0.05 mm, fiber length: 15.0 to 50.0 mm, natural twist number 140 to 240 times / 25 cm) is used as a raw material, and this is used with a ball breaker and a cotton hitting machine. Rather, cotton was made. Rather, the cotton was cut into a width of 14 cm and lightly wound up into a hollow iron core. Next, this was charged into a carbonization furnace and gradually heated and heated in a non-oxidizing atmosphere, and then the temperature in the furnace was raised to 600 ° C. and heated at this temperature for another 3 hours for carbonization firing treatment. By doing so, a shaped carbide constituting the surface heating material was obtained. The shaped carbide was carbonized in exactly the same form as the raw cotton, and the structure became dense, and the dimensional change was 29% smaller than the raw cotton and 35% thinner than the cotton. The weight loss of the shaped carbide was 63%. Moreover, the specific gravity of the shaped carbide was 0.023.

  Next, the strength and stability of the shaped carbide constituting the surface heating material were tested. The results are shown in Table 1.

  From the results shown in Table 1, it is presumed that the true tensile strength at break of the carbonized fibers is also decreased, but the apparent tensile strength was not significantly different due to the mating effect. Further, it is considered that the increase in the lateral strength is due to the strengthening of the single fibers due to carbonization.

  Next, the shaped carbide constituting the surface heating material according to the present invention was immersed in water while boiling, and its stability was measured. The results are shown in Table 2.

  From the results shown in Table 2, raw rather than cotton has a large change in shape both horizontally and vertically, and particularly a large change in the horizontal direction. This means that the balance between the longitudinal fibers is weak. On the other hand, carbonized cotton has a relatively small shape change and a uniform surface condition.

Example 2
The same cotton as the raw material used in Example 1 was uniformly opened with a ball breaker and made into a porous form (a) and rayon yarn (viscose method, 1.5 denier long fiber) with a surface temperature of 400. Compared with the one obtained by cutting the corrugated shape into a length of 2.5 cm by using a pressing mold roll heated to ° C. (b) and No. 8 cotton canvas (c) as Comparative Example 1. A cotton rope (d) having a diameter of 4 mm as Example 2 and a braid (e) having a diameter of 2.5 mm knitted from the rayon yarn as Comparative Example 3 were respectively charged in the same carbonization furnace. Then, after heating with air shut off, the temperature was gradually raised and maintained for 2.5 hours, and then heated to 840 ° C. and heated for 3.5 hours to carry out carbonization firing treatment.

  As a result, both (a) and (b) were obtained in a mated porous cotton form. Next, after 5 samples of (a) to (e) are held at 800 ° C. and subjected to the steam activation treatment for 40 minutes, the samples are cooled to room temperature and taken out from the furnace, and each of (a) to (e) is performed. In order to compare the reactivity of the samples, the adsorption value of methylene blue was tested. The results are shown in Table 3.

  From the results shown in Table 3, it can be seen that the form of the adsorption capacity of the carbide is much more important than the material of the raw material. Therefore, the surface reactivity of the shaped carbide constituting the surface heating material according to the present invention is a high level not found in conventional products.

Claims (7)

In a method for producing a surface heating material constituted by a shaped carbide composed of a combination of single fibers,
Prepare a raw material of a porous structure consisting of a combined composite of cellulose single fibers with twisted, wavy, crimped forms,
Without adding a binder, the raw material is heated in a non-oxidizing atmosphere as it is in a non-oxidizing atmosphere, and subjected to carbonization firing treatment. By the carbonization shrinkage generated by this treatment, the combined bond between the single fibers is strengthened. A method for producing a surface heating material, characterized by stabilizing and strengthening the structure.   The method for producing a surface heating material according to claim 1, wherein the cellulose single fiber is a cotton fiber.   The method for producing a surface heating material according to claim 1 or 2, wherein the material of the porous structure is at least one selected from loose fiber, wrap, sliver, and roving.   The method for producing a surface heating material according to claim 1, 2 or 3, wherein the cellulose single fiber has a fiber width of 0.01 to 0.08 mm.   The method for producing a surface heating material according to any one of claims 1 to 4, wherein a bulk specific gravity of the shaped carbide is 0.02 or more.   The method for producing a surface heating material according to any one of claims 1 to 5, wherein a bulk specific gravity of the shaped carbide is 0.025 or less.   The method for producing a surface heating material according to any one of claims 1 to 6, wherein the weight of the shaped carbide is 33 to 45% of the raw material of the porous structure.