JPH03166701A - Resistor - Google Patents

Abstract

PURPOSE:To obtain a flexible resistor having a positive temperature coefficient by applying metal-plating to carbon black through an electroless method, lowering the resistance value of carbon black and combining the metal-plating treated carbon black with a high molecular compound manufactured through a graft method. CONSTITUTION:A resistor is composed of carbon black, a surface of which is plating-worked by silver or nickel, and a graft complex prepared by manufacturing a high molecular compound through a graft method. That is, carbon black is metal plating treated through an electroless method, and a plating layer is formed onto the surface of carbon black, thus lowering the resistance value of carbon black in the presence of the plating layer. Consequently, when the metal-plating treated carbon black is combined with the high molecular compound (the graft complex) manufactured through the graft method, the resistance change of interparticle contacts in the complex is increased. Accordingly, the flexible resistor having a positive temperature coefficient can be acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resistor comprising carbon black and a graft composite.

[Conventional technology]

Conventionally, composites made of carbon black and polymer compounds have been widely used as resistance materials, but in this type of composite, when crystalline polymers such as polyethylene or polypropylene are used, the temperature decreases near the transition point. It is known that the electrical resistance of resistive materials varies greatly. However, it has been difficult to obtain a resistor with a large positive temperature coefficient when combined with a flexible polymer material.

[Problem to be solved by the invention]

The present invention solves this drawback by treating carbon black with metal plating using an electroless method to lower its resistance value, and combining it with a polymer compound (graft composite) produced by a grafting method. The technical problem is to increase the change in contact resistance between particles inside the composite and to provide a flexible resistor having a large positive temperature coefficient.

[Means to solve the problem]

The gist of the present invention relates to a resistor consisting of a carbon plaque whose surface is plated with silver or nickel, and a graft composite prepared by a grafting method with a polymer compound.

[For production]

Carbon black is metal-plated using an electroless method to form a plating layer on the carbon black surface, so the presence of this plating layer lowers the resistance value of carbon black.

When the plated layer is formed on a polymer compound (grafted composite) prepared by the grafting method, the resistance change of the interparticle contact inside the composite becomes large, and therefore a flexible resistor with a large positive temperature coefficient is formed. is obtained.

〔Example〕

In the electroless plating method used in the present invention, carbon black is activated with palladium chloride or tin chloride, then treated with a silver or nickel bath, thoroughly washed with water, and dried to obtain treated carbon black. .

Next, in the presence of treated carbon, vinyl monomers were added to N,
``The resistor according to the present invention is obtained by polymerizing with a radical catalyst such as azobisisobutyronitrile or benzoyl peroxide.

The resistor must be cross-linked and cured after being molded into an appropriate shape.
<A monomer configuration containing a necessary and reactive group is desirable.

Incidentally, the grafting method is a copolymerization reaction in which a branch of an arbitrary polymeric substance is grafted onto a polymeric substance that serves as a trunk, and a compound that has successfully undergone the grafting method is a graft complex.

In the case of a resistor using a graft composite produced by a grafting method, the resistance value is particularly high, so that the effect of the present invention becomes remarkable when the present invention is applied to a resistor using a graft composite.

Specific examples are shown below.

Example 1 Carbon black [Furnace black (Fil black A) 1] treated by the following plating treatment method 1
3 g of methacrylic acid n-dodecyl ester monomer 6. in a 200 mQ eggplant flask. e'i'g and 0.39 g of acrylic acid monomer were dispersed in a cyclohexanone solvent, and 2% by weight of the monomer amount of N,
N'azobisisobutyronitrile was added, and the temperature was raised to 90°C to conduct a polymerization reaction for 8 hours.

After the reaction, the mixture was cooled, 1.94 g of epoxy resin (Araldite GY260) was added as a curing agent, and the mixture was stirred again at room temperature for 1 hour. This was applied as a resistance paint onto a ceramic substrate or polyester or glass cloth and pre-dried (70°C, 1 hour). , followed by curing at 160°C for 2 hours.

The resistance value of the thus obtained practical product was approximately 100 kΩ. Further, the resistance temperature characteristics are as shown in FIG. The resistance value increased rapidly at 120°C. It was found that when no plating treatment was performed, the amount of carbon increased, but the resistance value remained almost the same, and the change in resistance was also small.

Plating treatment part 1 The activation treatment performed on 10 g of carbon black before plating is performed using the activated palladium chloride method.

The solution composition is as follows.

Palladium chloride tg Hydrochloric acid 10cc Water 4000cc Processing time
Chemical plating treatment was performed following water washing at a treatment temperature of 30° C. for 1 hour.

Its composition is as follows.

Nickel chloride 60 g/1 Sodium hypophosphite 12 g/1 Sodium citrate 95 g/1 pH 5.0-5.8 Treatment time
4-hour treatment temperature: 30°C After plating, the plate was thoroughly washed with water and dried.

Example 2 Carbon black was plated according to the plating method 2 below.

Hereinafter, in the same manner as in Example 1, polymerization reaction, coating on the substrate,
Precuring and curing were performed, and the resistance temperature characteristics were investigated. The results are shown in Figure 2.

It can be seen that the change in resistance value is large compared to the resistor using untreated carbon black.

Plating Process 2 Carbon black IOg was activated using the following process.

Stannous chloride 5g Hydrochloric acid A small amount of water 1000cc This activation treatment was carried out at 30°C for 1 hour, and then washed with water.

Chemical plating was performed under the same conditions as in the plating process part 1 above.

Example 3 Carbon black was plated according to the plating method 3 below.

Hereinafter, in the same manner as in Example 1, polymerization reaction, coating on the substrate,
The results of preliminary curing and curing and examination of the resistance temperature characteristics are shown in Figure 3.

It can be seen that the change in resistance value is larger than that of the resistor using untreated carbon black.

Plating treatment part 3 The carbon black log was subjected to the following treatment.

The activation treatment was performed in the same manner as the method of plating treatment No. 2 above.

Further, chemical plating was performed using the following solution composition.

Nickel chloride 24g NiOH 12g Ammonia A small amount of water 400g This plating treatment was carried out at 30°C for 1 hour, and then washed with water and used for the experiment.

〔Effect of the invention〕

Since the present invention is constructed as described above, it provides a flexible resistor having a large positive temperature coefficient.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a resistance temperature characteristic graph showing the resistance change with temperature in Example 1, and FIG. 2 is a resistance temperature characteristic graph showing the resistance change with temperature in Example 2. Resistance Temperature Characteristic Graph FIG. 3 is a resistance temperature characteristic graph showing the change in resistance value with respect to temperature in Example 3. 7/Temperature ('C)

Claims (1)

[Claims] A resistor consisting of carbon black whose surface is plated with silver or nickel and a graft composite made by grafting a polymer compound.