JPS6131350A - Manufacture of 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] 〔Technical field〕 The present invention relates to a method for producing a heating element having positive properties.

[Background technology]

Conventionally, barium titanate PTC ceramics are obtained by adding a semiconducting agent to barium titanate and making it porcelain.
It is widely used as a safe constant-temperature heating element because it has excellent properties such as positive temperature-resistance characteristics, static voltage-current characteristics, and dynamic characteristics of 1 hour-current. Other applications include electronic components. When using this as a heating element, various measures are taken to increase the surface area in order to obtain a high calorific value. A common example is a honeycomb-shaped heating element, but since this is made of ceramic that is inherently fragile and has many holes that allow air to pass through, the wall thickness between the holes becomes thinner, making it more prone to cracking. The drawback was that it became easier.

[Purpose of the invention]

In view of the above-mentioned current situation, an object of the present invention is to provide a method for manufacturing a heating element that has excellent impact resistance and is difficult to break.

[Disclosure of the invention]

In order to achieve the above-mentioned object, this invention produces a fired product by mixing barium titanate calcined grains and organic resin grains and firing the mixture in an inert gas in order to manufacture a heating element having positive characteristics. , the gist of which is a method for manufacturing a heating element characterized by impregnating pinholes in the fired product with resin. This will be explained in detail below.

The barium titanate calcined product is produced by pressing as follows.

First, a small amount of a semiconductor agent NbzOs or the like is added to BaC0a and Ti0z, wet mixed, dried, and then calcined. Next, add a small amount of acceptor forming agent Mn0z to this.
+ Grain boundary control agent 5i02 etc. are blended, wet mixed again and then dried to obtain calcined barium titanate grains.

Next, the above calcined particles and organic resin particles such as polyethylene particles are mixed and fired in an inert gas, and as shown in Figure @1, barium titanate particles 1... are mixed with carbon particles 2...
..., and there are many pinholes 3 between them...
Obtain a porous plate-shaped fired product in which . Thereafter, these pinholes 3 are impregnated with resin, an electrode layer is provided on the surface, and a heating element is manufactured. There are no particular restrictions on the formation of the electrode layer.

Since this heating element is fired in an inert gas as described above, the barium titanate particles 1... and the carbon particles 2
In other words, the carbon particles form an electrical bond between the barium titanate particles, so that the resistance of the heating element can be appropriately controlled. In addition, since the barium titanate porcelain is impregnated with resin,
This results in a heating element that is highly impact resistant and difficult to break.

Next, an embodiment of the method for manufacturing a heating element according to the present invention will be described together with a conventional example.

(Example 1) BaCO3 and Ti()2 were used as the main components, a trace amount of a semiconductor forming agent Nb2O5 was added thereto, wet mixing was performed with water in a ball mill, followed by drying and calcining at 1150°C for 2 hours. Next, a trace amount of Mn0z + 5i is added to this calcined product.
02 was added thereto, wet mixing was performed again using water in a ball mill, and then the mixture was dried. A PVA aqueous solution having a ratio of 5 as a binder was added to the dry material at a ratio of 20 Wt to the dry material, and polyethylene particles pulverized and granulated using a 100 mesh sieve were added in an amount of 10 wt% based on the dry material VC, and the mixture was dry mixed in an agate mortar. . After drying this mixed powder, 2 ton/c
It was heated with direct acid at a pressure of d to form a disc with a diameter of 20 sheaths, and fired in an inert gas at 1250 to 1310°C for 1 hour. The fired product had many pinholes. The pinholes of this porous fired product were impregnated with silicone resin for bottling under pressure.

(Example 2) A porous fired product produced in the same manner as in Example 1 was sandwiched between Teflon plates and pressed while heating from both sides to impregnate the pinholes with Teflon resin.

(Conventional example) A conventionally used barium titanate-based PTC ceramic was manufactured using the same materials and steps as in Example 1 without heating the polyethylene particles.

Barium titanate-based PTC of Example 1.2 and Comparative Example
An electrode layer is provided on the surface of the ceramic to serve as a heating element, and its specific resistance and RT characteristics at room temperature.

We investigated drop impact resistance. The specific resistance and drop impact resistance at room temperature are shown in the table below. Drop impact resistance is determined by dropping the material onto a hardened cement material and determining the drop impact resistance at a height that is at the limit of cracking. Further, the RT characteristics are shown in FIG. 2 using a logarithmic graph.

The example shows excellent PTC characteristics and also shows higher drop impact resistance than the conventional example.

〔Effect of the invention〕

The method for producing a heating element according to the present invention involves mixing barium titanate calcined grains and organic resin particles and firing the mixture in an inert gas to produce a fired product. Since it is characterized by impregnating the pinholes of objects with resin, it is possible to manufacture a heating element that has excellent impact resistance and is difficult to break.

[Brief explanation of the drawing]

Fig. 1 is an enlarged explanatory diagram showing the internal structure of the fired product obtained by the &1 method of the heating element according to the present invention. Fig. 2 shows the R-
This is a graph showing T characteristics. 1...Barium ticunate particles 2...Carbon particles 3...Pinhole agent Patent attorney Takehiko Matsumoto Temperature ('C) Procedural amendment distributed November 2, 1980 Patent application filed in 1988 No. 151088 2, Name of invention Process for manufacturing heating element 3, Relationship with the case of the person making the amendment Patent applicant Location 1048 Kadoma, Kadoma City, Osaka Name (583) Representative of Matsushita Electric Works Co., Ltd. (Kobayashi Iku 4, No agent 6, Specification subject to amendment 7, Contents of amendment (1) The table on page 6 of the specification is corrected as follows.

Claims (1)

[Claims] (1) In manufacturing a heating element with positive characteristics, barium titanate calcined particles and organic resin particles are mixed and fired in an inert gas to create a fired product, and the resin is inserted into the pinhole of this fired product. A method for producing a heating element characterized by impregnation.