JPH0473884A - Ribbon heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ribbon-shaped heater that is effective for keeping or heating equipment members such as pipes and nozzles.

[Conventional technology]

Various shapes of heating elements have been developed, such as rod-shaped, tubular, and planar shapes, but for heat retention and heating of vibrators, nozzles, etc. used as components in various industrial equipment, it is necessary to directly attach them to these components. It is highly effective in practical terms to use a long ribbon heater in the form of a wire or a band that can be wrapped around. Conventionally, this type of heater has been made by attaching an electrode under pressure to a tape-shaped resistor extruded from a material in which conductive fine powder is dispersed in a crystalline resin (Japanese Patent Application Laid-open No. 61-288390), and a tube-like heater. A tubular heater whose outer surface is coated with a resin liquid mixed with conductive powder to form an electrically heating resin layer (Japanese Unexamined Patent Publication No. 63-79670), a heater whose heating element is a tape-shaped metal foil conductor (Japanese Unexamined Patent Application Publication No. 1983-1999) Showa 56-8535
Publication No. 2), etc. have been proposed.

[Problem to be solved by the invention]

However, the conventional heaters described above generally do not have sufficient material stability with respect to bending flexibility, and furthermore, there are problems in that they do not satisfy required characteristics in terms of uniform heat generation, high temperature resistance, etc.

An object of the present invention is to solve the above-mentioned problems and provide a long ribbon heater that has sufficient bending flexibility for practical use and material stability that can withstand it, and has excellent uniform heat generation properties and high temperature resistance. It is in.

[Means to solve the problem]

A ribbon heater according to the present invention for achieving the above object is formed by molding a composite of conductive carbon black and fibrous polytetrafluoroethylene in which two metal electrode wires are embedded in parallel in the axial direction. The structure is characterized in that a silicone resin forms an outer covering layer on the surface of the linear heating element.

The conductive carbon blank constituting the linear heating element of the present invention is a basic component for producing resistance heat generation by energization, and includes furnace black, acetylene black,
Of the by-product black, the nitrogen adsorption specific surface area (N, SA
) is 80~220I12/g, DBP oil absorption is 120~
The particles are selected from those having a particle property range of 170 d/100 g.

Fiberized polytetrafluoroethylene refers to polytetrafluoroethylene that has been converted into fine fibers by applying shearing force or compressive force, and in the structure of the present invention, it is composited with the above-mentioned conductive carbon black to form an integrated structure. It functions as a skeletal material for forming.

A linear heating element is formed by combining these conductive carbon blacks and fibrous polytetrafluoroethylene into a linear shape, and electrode wires made of a highly conductive metal such as copper are inserted into the structure in the axial direction. It is integrally molded so that it is buried parallel to the

The ribbon heater according to the present invention has an electric wire structure in which an insulating coating of silicone resin is formed as an outer layer on the surface of the linear heating element.

A ribbon heater having such a configuration can be manufactured by the following steps.

Fiberized polytetrafluoroethylene is blended with conductive carbon black in a range of 5 to 95% by weight, and the mixture is stirred. Next, the mixed powder is thoroughly kneaded by adding an appropriate kneading aid and putting it into a kneader such as a rotary vane type kneader that applies shearing force. As the kneading aid, for example, glycerin, turgent naphtha, kerosene, etc. can be used. Through this kneading process, polytetrafluoroethylene is converted into fine fibers and dispersed within the structure.

The kneaded material is then continuously molded into a long linear body using an extrusion molding device. Means for embedding two metal electrode wires in parallel in the axial direction within the tissue of the linear body include a method of sandwiching and integrating the two metal electrode wires between linear bodies that have been extruded into a grooved shape in advance, and a method of integrating the two metal electrode wires by extruding them into a grooved shape. There is a method of simultaneous integration by extruding the metal electrode wire along with it in a step, but any method may be used. The molded linear heating element is washed with water to remove the kneading aid component, and after drying, an insulating outer layer of silicone resin is formed.

To form an outer layer of silicone resin on the surface of the linear heating element, a method of covering the linear heating element with a heat-shrinkable silicone resin tube and heating it can be effectively applied.

(Function) According to the present invention, a conductive carbon blank and a fibrous polytetrafluoroethylene are entangled in a bent shape in which a linear heating element encloses two metal electrode wires in parallel to the axial direction. It is composed of a composite structure with a degree of freedom, and a thin insulating coating layer made of silicone resin is formed on its surface.
No variation in electrical resistance, tough, uniform heat generation, heat resistant
A long ribbon heater with excellent corrosion resistance and flexibility is provided. Therefore, it can be easily wound around a pipe, nozzle, etc., and it is guaranteed that the entire body is heated uniformly without temperature unevenness.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

(1) Fabrication and structure of ribbon heater Nitrogen adsorption specific surface area (NzSA) 206 m2/g,
Conductive carbon blank with D B P oil absorption of 155 I11/long (manufactured by Tokai Carbon ■, Toka Black #5500) and fibrous polytetrafluoroethylene (manufactured by DuPont Mitsui Fluorochemical ■, 6C-) with 80% by weight J) 20% by weight was added to a 50% aqueous ethanol solution, stirred and mixed thoroughly, and then filtered and dried. Add 1.5% of conductive carbon bra to this mixed powder.
An amount equivalent to double the amount of glycerin was added as a kneading aid, and the mixture was kneaded using a blast mill mixer at a temperature of 100'C and a rotation speed of 5 rpm.

The kneaded paste is continuously molded using an extrusion molding device with a long diameter of 2 m11 while entraining two copper wires at intervals in the extrusion direction.
It was formed into an elliptical linear body. This linear molded body was immersed in hot water at 60"C for 1 hour to remove the glycerin component, dried, and further heated at a temperature of 300°C to produce a linear heating element.

Next, the linear heating element was inserted into a heat-shrinkable silicone resin tube (manufactured by Shin-Etsu Chemical Co., Ltd., 5T-DC) and heated to form an insulating film that tightly adhered to the surface.

Figure 1 is a perspective sectional view showing the ribbon heater of the present invention obtained by the above process, and the second view is taken along A-A in Figure 1.
FIG. In these figures, 1 is a linear heating element formed by combining a conductive carbon blank and fibrous polytetrafluoroethylene, and 2 is a state in which the linear heating element is embedded in the tissue in parallel with the axial direction. 3 is an outer covering layer of silicone resin, and 4 is a lead wire attached to the end of the metal electrode is2.

(2) Performance evaluation of ribbon heater The characteristics of the ribbon heater described above were measured and found to be tensile strength of 16.8 kgf/cm, elongation of 35.4%, electrical resistivity of 0.100 cm, and flexible flexibility. It was something.

Next, the ribbon heater is energized via the lead wire, and 15
As a result of measuring the temperature distribution when heat was generated to a temperature of 0°C, the range of variation was ±5°C, indicating uniform heat generation property. Furthermore, the relationship between temperature and electrical resistance was as shown in the graph of FIG. 3, and it was confirmed that resistance fluctuations depending on the temperature range were slight.

These electrical properties were stable even after repeated bending.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a product that satisfies the requirements required for a ribbon heater, such as uniform high-temperature heat generation properties, high strength, and bending stability. Therefore, it is extremely useful especially for applications such as heat insulation and heating of industrial equipment members such as pipes and nozzles.

Figure 1

[Brief explanation of the drawing]

FIG. 1 is a perspective sectional view showing the structure of a ribbon heater according to the present invention, and FIG. 2 is a plan sectional view taken along line AA' in FIG. FIG. 3 is a graph showing the relationship between temperature and electrical resistance in the example. 1... Linear heating element 2... Metal electrode wire 3...
Coating outer layer 4...Lead wire applicant Tokai Carbon Co., Ltd. agent Patent attorney Masaya Takahata Figure 2 Procedural amendment (voluntary) Figure 3 August 10, 1990

Claims (1)

[Claims] 1. On the surface of a linear heating element formed by combining conductive carbon black and fibrous polytetrafluoroethylene, two metal conductive wires are embedded parallel to the axis.
A ribbon heater characterized by forming an outer covering layer of silicone resin.