JPS6026281B2 - Carbon-based resistor for sliding resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel carbon-based resistor for a sliding resistor, and particularly to a resistor that is wear-resistant and has a long sliding life.

A variable resistor has a resistor with electrodes formed on an insulating substrate, and a sliding contact slides on the surface of the resistor while maintaining a constant pressure so that there is electrical continuity between the resistor and the resistor. It is structured like this. When the sliding element slides back and forth on the surface of the resistor, the resistor wears out due to friction. If this amount of wear is large, it will not be able to withstand long-term sliding, and the life of the sardine will be shortened. The sliding life varies depending on various conditions such as the material of the sliding contact and the contact pressure, but it is generally 15,000 years.
It is normal to have around 5,000 mountains. The present invention relates to a carbon-based resistor that has the highest wear resistance, has a long sliding life, and has extremely low sliding noise. As is well known, carbon-based resistors are made by dispersing conductive particles such as carbon particles in a solution of an initial vertical polymer of a binder, that is, a thermosetting resin, and then applying a resistor paste to ceramics, phenolic resin, epoxy resin, etc. It is obtained by coating a diallyl phthalate resin or the like on an insulating substrate, evaporating the solvent by heat treatment, promoting the polycondensation reaction of the resin, and sufficiently curing the resin. However, conventional resistors do not have sufficient wear resistance and have a short sliding life, so they cannot be used in industrial equipment as described below, and are therefore used for limited purposes. With the recent development of industry, throttle sensors and
There is a strong demand for resistors with low sliding noise and long sliding life in the fields of air flow sensors, computer terminals, industrial sewing machines, etc. Therefore, various methods have been proposed to improve the superdynamic life. [11] A method of mixing a lubricant into a resistor, such as sheath nitride, molybdenum disulfide,
Mix particles such as graphite. In addition, a method of obtaining a resistor with a high resistance value and a long sliding life by mixing particles obtained by partially fluorinating graphite with fluorine gas under heating is mixed into the resistor (Tokuko Showa). 46-41274)
etc. A known method is to mix tetrafluoroethylene as a lubricant in the '2' resistor and use epoxy resin and melamine as a binder, or epoxy resin and phenol as a hardening agent (see Japanese Patent Publication No. 7071/1983). There are various other methods such as increasing the film thickness.

However, both methods have problems when put into practical use. For example, in the '11 method of adding lubricant, if the amount added is increased to reduce friction, high resistance cannot be obtained with graphite, and high contact resistance cannot be obtained with molybdenum disulfide due to its insulating properties. The disadvantage is that the noise caused by the resistor's vibration is large. In addition, in the fluorination of graphite, the reaction window size varies considerably depending on reaction conditions such as the shape and size of the graphite particles, reaction rate, and atmosphere, so it is difficult to industrially obtain a constant fluorine-G ratio. However, in practice, there are difficulties in producing products with a constant value, and the service life is also not satisfactory. It is said that when tetrafluoroethylene of [21] is mixed, the miscibility with the binder is poor and a good quality paste cannot be obtained unless it is mixed in at 10% or less. In this respect, the effect of reducing frictional resistance is small. The present invention was made to improve the pitting points of conventional sliding resistors, and its objectives are to provide wear resistance, long sliding life, low sliding noise, and to improve sliding resistance. This provides a dexterous resistor.

As a result of research to achieve the above object, the inventors of the present invention formed two layers, an adhesive layer and a resistance layer, on an insulating substrate, which is completely different from the conventional method of forming a direct sliding resistor on an insulating substrate. We have discovered that by doing so, it is possible to obtain a resistor that adheres firmly to the substrate, has very little wear, and has a long sliding life. In particular, the resistor layer is coated on the adhesive layer that has been cured to the extent that printing is possible when the polymerization or longitudinal polymerization of the synthetic resin in the adhesive layer is not completed, and the resistor layer is heated to react with the binder resin in the resistor layer. When this is done, a crosslinked structure is generated between the two layers, resulting in extremely strong adhesion. Melamine resin has a high hardness and a coefficient of friction of 4, but its adhesion is poor, so resistance pastes made using melamine resin as a binder do not adhere well to alumina substrates, despite having excellent wear resistance. do not.

Furthermore, a resistor made by printing and applying a melamine base on an epoxy substrate and heat-treating the same also peels off from the substrate. In addition, when resistor paste is manufactured by blending melamine resin with epoxy resin or by pre-vertical polymerization of both as a binder, the adhesion to the substrate is improved, but the hardness and
It is inferior to the properties of melamine resin main pots in terms of wear resistance, and is not fully satisfactory in terms of sliding life. However, as in the present invention, if an epoxy-based synthetic resin is used as the adhesive for the adhesive layer and a melamine resin is used as the binder for the resistor layer, and heat treatment is performed under appropriate conditions as described above, the melamine resin will harden the epoxy resin. It acts as an agent and forms a crosslinked structure, making it extremely easy to adhere. According to the present invention, a resin binder with the best hardness and abrasion resistance can be selected for the resistor layer, and a resin with the ability to most firmly bond the substrate and the resistor layer can be selected for the intermediate adhesive layer. In addition, it is possible for the resistor layer and the adhesive layer to undergo a chemical crosslinking reaction at the contact surface, resulting in extremely strong adhesion, resulting in not only a long sliding life but also mechanical resistance. A resistor with excellent properties can be obtained. Molecular weight 1000-3000 epoxy equivalent,
500 to 1000 solid epoxy resin is dissolved in a solvent such as butyl carbitol, an equivalent amount of a curing agent such as dicyandiamide is added to this, and the mixture is coated onto an insulating substrate in the desired shape, and the epoxy groups undergo a ring-opening reaction. By performing heat treatment at a temperature that does not allow rapid striped polymerization reaction to proceed, an epoxy resin adhesive layer with a dry (semi-hard surface) surface without stickiness can be obtained.

A melamine resin paste obtained by dispersing conductive particles such as carbon particles or a mixture of conductive flame particles and lubricant particles was printed and coated in a predetermined shape on the layer in which the condensation polymerization had not yet been completed. After that, if the adhesive layer and the resistor layer binder are simultaneously subjected to a condensation reaction by heating, the substrate and the epoxy resin layer, and the epoxy resin layer and the resistor layer will be firmly adhered to each other, and the superdynamic surface of the obtained resistor will be It is possible to form a melamine resin film that is hard, has little friction, and has very little wear on the surface of the epoxy resin film, and it is also possible to chemically crosslink each layer depending on the type of resin and conditions. It is possible to manufacture a carbon-based film resistor that is mechanically superior and has a long sliding life. Similarly, a melamine resin paste in which carbon particles or a mixture of carbon particles and lubricant particles as guide fin particles are dispersed is applied onto a semi-cured phenolic resin film formed on an insulating substrate, and heat treated. , it is possible to obtain a melamine resin film with strong adhesion. In addition, by mixing and dispersing carbon particles as conductive particles in the epoxy resin solution, the adhesive layer has conductivity, and this conductivity allows electricity to flow between the electrode part formed on the insulating substrate and the upper resistance layer. It is possible to provide continuity. As a binder for the resistor layer, melamine resin,
Examples include, but are not limited to, diallyl phthalate resin.

Examples of the lubricant include, but are not limited to, natural graphite, synthetic graphite, nitrided carbonate, molybdenum disulfide, and graphite fluoride. The solvent may be any solvent as long as it has good compatibility, and examples thereof include butyl carbitol, butyl carbitol acetate, phthalate esters, sebacate ester, and the like. The resistor for a sliding resistor of the present invention was brought into contact with the surface of the resistor with a ▽-shaped silver-palladium metal contact with a tip radius of 0.15 at a contact pressure of 10 yen, and the resistor was shaken 2500 times per minute. 10 in the middle 3 ribs
A sliding life test was conducted by sliding back and forth 00 times.

The wear amount of the resistor was measured using Surfcom (Tokyo Seimitsu) based on the trace of the contact points generated on the resistor surface. the result,
The sliding life of a conventional single-layer carbon resistor using a phenolic resin binder was about 5 million times and the amount of wear was 20 mm, but the two-layer type according to the present invention has an epoxy resin for the lower layer and a melamine resin for the resistance layer. Even after being used in port up to 15 million times, the amount of wear was only 6 French. Next, examples of the present invention will be described.

Example 1 Solid epoxy resin EPICOAT #100150 was dissolved in butyl carbitol 50, and artificial graphite OP-1 was dissolved therein.
Mix 7 & 30 minutes and thoroughly disperse.

By adding artificial graphite, conductivity between the resistor layer applied next and the electrodes previously formed on the alumina insulating substrate is ensured. Dicyandiamide 2 is added as a curing agent to the epoxy resin solution. The viscosity of this paste is 2
5) It was approximately 1000 poise in C and was passed through screen printing. This paste was applied to a predetermined shape on an alumina substrate by screen printing, and then heated at room temperature.
After leaving it between the grains, it was dried in a vacuum dryer at 25 Hg, 130
It was dried for 1 hour. On the thus obtained epoxy adhesive layer, a paste obtained by mixing and dispersing GP-78 and GP-30 in a melamine resin solution of E50 is printed and coated in a predetermined shape. This shape accuracy can be easily achieved by screen printing. 15 at room temperature after application
After being left for a minute, heat treatment was performed for 210,002 hours.
The resistance value of the obtained resistor was IKO/□, and the sliding noise was 2.3%. The results of the sliding life test of this resistor are shown in Fig. 1, and the wear amount of the sliding locus is 5 mm.
This is significantly greater than the wear amount of 20mm for the conventional product with a single layer structure that uses phenolic resin as a binder, as shown in Figure 4.
In the case of sill and follower products, the resistor wears considerably due to the sliding of the contacts, and the contact trajectories reach all the way to the board surface. The sliding noise of the resistor of the example after the sliding test was 2.3%, which was unchanged from the value before the test. Example 2 Solid epoxy resin Epiquat #100440 was dissolved in 50% butyl carbitol and 1.6% dicyandiamide was added.
The material to which the adhesive is added is used as the lower adhesive layer.

GP- in melamine resin solution Cymel 325, 100 ta
A paste for sliding resistance was prepared by mixing and dispersing 78, 3M, and 15 nitrides. A resistor was prepared using the same procedure as in Example 1. The resistance value of the obtained resistor was IKQ/□, and the sliding noise was 2.8%. The results of the sliding life test were as shown in Figure 2, and the amount of wear was 4rm. The sliding noise was 2.5% after the test, and there was no change. Example
3 Dissolve phenolic resin API07, 50 mm in butyl carbitol acetate 80 mm, mix and disperse GP-7 & 35 mm, print and coat on an insulating substrate, and dry in a vacuum dryer for 25 mm.
GP in melamine resin solution Cymel 32F 100T on top of the lower adhesive layer dried for 100 hours CI hours.
A paste obtained by mixing and dispersing 78 and 30 minutes was applied by printing as a paste for sliding resistance, and heat treatment was performed for 1 hour at 190 hours.

The resistance value of the obtained resistor was IKQ'□, and the sliding noise was 2.5%. As shown in Fig. 3, the results of the sliding life test showed that the amount of wear was 5 mm, and the sliding noise was 2.5%. As shown in Figure 4, the results of a sliding life test of a conventional product with a single-layer structure using phenolic resin as a binder showed that the resistor was significantly worn, and the sliding trajectory of the contact reached the substrate surface and the resistive film in this area disappeared. This indicates that it cannot withstand 10 million uses.

Therefore, the sliding noise after the test could not be measured. On the contrary, the results of the sliding life test of the two-layer structure resistors according to Examples 1, 2, and 3 of the present invention show that the amount of wear indicating the sliding trajectory is the first,
Figures 2 and 3 show that the skin is 3r ~ 5mm, and that the strain noise value does not change and can be used further.
This proves the superiority of the present invention. As described above, the resistor of the present invention has excellent abrasion resistance and a long sliding life that have never been seen before, and has excellent characteristics such as low sliding noise.

The adhesive layer paste and the resistor layer paste have excellent printability and are characterized by being extremely easy to manufacture.

[Brief explanation of the drawing]

Figures 1, 2 and 3 are embodiments 1, 2 and 3 of the present invention, respectively.
FIG. 3 is a cross-sectional view of the resistor showing the sliding locus of the contact after a sliding life test of the resistor. FIG. 4 is a cross-sectional view of the resistor showing the contact locus after the sliding life test of the conventional resistor. 1 is the substrate surface, 2 is the resistor film surface, and 3 and 4 are the sliding trajectories of the contacts. Qin l Zuzui 2 Diagram 3 Diagram 4 Diagram

Claims (1)

[Claims] 1. A carbon-based resistor for a sliding resistor having a two-layer structure characterized by forming an adhesive layer and a resistance layer on an insulating substrate, in which the adhesive layer is made of phenolic resin or epoxy resin alone or mainly composed of them. This is a conductive adhesive layer made by containing conductive particles in a mixture with other adhesive synthetic resins, and on top of the conductive adhesive layer is a resistor made of conductive particles and melamine resin, and a lubricant such as graphite, molybdenum disulfide, or boron nitride. , a carbon-based resistor for a sliding resistor, comprising a resistance layer containing one or a mixture of two or more of tetrafluoride resins.