JPH02156502A - Organic temperature sensitive element having self-temperature control characteristic - Google Patents

Abstract

PURPOSE:To enable the title temperature sensitive element to discharge the self-temperature control function in sharp fluctuation of positive characteristic by a method wherein graphite or carbon black is compounded of a low dimensional material mainly composed of bridging high molecule and linear high molecule. CONSTITUTION:Graphite or carbon black is compounded of a low dimensional material mainly composed of bridging high molecule and linear high molecule. The title temperature sensitive element can be manufactured by blending the conductive graphite or carbon black with monomer of bridging high molecule, fine grains or liquid polymer of linear high molecule compound as the low dimensional material and low molecular organic compound to be blended and polymerized in an organic solvent. Through these procedures, the said element discharging the self temperature sensing and controlling functions in various phases as a sensor of molecular level as well as having the stable temperature- conductive characteristics in the least with-time fluctuation in the resistance values regardless of repeated applications can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel organic temperature sensing element that has specific temperature detection and self-temperature control functions in a low temperature range of 100° C. or less.

[Conventional technology]

Conventionally, conductive resins or semiconductive resins are formed by blending thermosetting resins or thermoplastic resins with conductive substances such as graphite, carbon black, or metal powder, and the excellent properties of these organic materials are used to create electronic Widely used as parts or heating elements.

However, their fatal drawback is that they lack stability and have no chain to rely on. In particular, changes over time after long-term use could not be avoided.

[Problem to be solved by the invention]

For example, stable temperature in the low temperature range of about 100℃ or less.
It has conductive properties, and its electrical resistance value does not change over time even after repeated heating and cooling, and it also has a self-temperature control function that detects a specific temperature and has a large positive characteristic change in a specific temperature range, making it highly stable. The development of organic materials is required.

[Means to solve the problem]

As a result of intensive studies to achieve the above-mentioned problem, the present inventor discovered that graphite or carbon black has a solid covalent bond structure in the form of a two-dimensional typical six-membered ring network planar structure, and that the bonding strength between the planar layers is comparable. It is loose and slips well, but it has a considerable adsorption force and swells and degenerates between planes.In the secondary plane, it exhibits insulating properties as a so-called conjugated covalent bond, but between the planes of the layer, there is a so-called π-electron cloud. Focusing on the fact that graphite or carbon black exhibits conductivity similar to that of metals, we expanded the distance between the eyebrows by adsorbing derivatives with strong adsorption properties between the eyebrows of graphite or carbon black, and added crystalline low-molecular-weight materials between the inorganic layers above and below the graphite. The conductive resistance between the eyebrows can be freely controlled by infiltrating an organic compound to replace part or all of the adsorbed derivative, or by directly adsorbing it to an inorganic layer to form a crosslink, and by changing the length of the crosslinked molecule. We have discovered that this can be done, and have completed the present invention.

That is, the organic textured temperature element having self-temperature control properties of the present invention is characterized by being made of a composite of graphite or carbon black with a low-dimensional substance mainly consisting of a crosslinked polymer and a linear polymer.

The temperature-sensitive element according to the present invention is produced by blending conductive graphite or carbon black with a cross-linked polymer heptamer, a fine powder or liquid polymer of a linear polymer compound which is a low-dimensional substance, and a low molecular weight organic compound. It can be produced by blending and polymerizing in a solvent.

In the present invention, examples of graphite or carbon black include natural or artificial graphite, furnace black, acetylene black, etc., and the particle size is 1μ or less, especially 0.1μ.
It is preferable to use a material less than μ.

As the crosslinked polymer, thermosetting resin monomers forming a three-dimensional network structure, such as epoxy resins, melamine resins, polyurethane resins, silicone resins, and their modified resins are preferably used.

Linear polymer compounds include polyethylene and ethylene vinegar8
Examples include vinyl copolymers, ethylene-vinyl chloride copolymers, olefin polymers such as polypropylene, diene resins such as liquid polybutadiene, ionomare resins, and preferred are liquid polybutadiene or crystalline fine powder polyethylene. It is.

Typical examples of low molecular weight organic compounds include linear alkane hydrocarbons having 20 or more carbon atoms and fatty acids thereof.

Examples of organic solvents or reaction inducers include aromatic hydrocarbons such as benzene, toluene, and xylene, alcohols such as n-butanol and n-propanol, and aliphatic compounds such as ethylene glycol, propylene glycol, and 1,4-butanediol. Glycol, cyclopenkune-1,2
Examples include alicyclic diols such as -diol, phenols such as hydroquinone, ketones such as methyl ethyl ketone, and tetrahydrofuran.

When manufacturing the temperature-sensitive element of the present invention, the above-mentioned related substances are blended into a conductive high-dimensional material consisting of graphite and a cross-linked polymer.
0 parts, graphite is 10 to 60 parts, and crosslinked polymer is 40 parts.
A suitable range is 90 parts.

If the amount of the crosslinked polymer exceeds 90 parts, the conductivity will deteriorate. In addition, if it is less than 40 parts, that is, if the graphite exceeds 60 parts, the effect of increasing the amount will be poor, and the basic conductivity at room temperature will differ depending on the type and amount of graphite or carbon black, but the specific temperature detection and self-temperature control characteristics can be determined uniformly, and if a cross-linked polymer is grafted with carbon black, it becomes a matrix of a conductive substance, so the basic conductivity will be different for each. After all, it can be determined uniformly.

In order to stabilize the conductivity, it is recommended that the linear (chain) polymer compound be added in an amount of 5 to 100 parts based on the total amount of the crosslinked polymer and graphite. good. When the amount exceeds 100 parts, the conductivity decreases drastically and exceeds the practical range.

Low molecular weight organic compounds, such as the above hydrocarbons, have a molecular weight of 3 to 30
The scope shall be within the scope of this section. If it exceeds 30 parts, the toughness of the product will decrease, and if it is less than 3 parts, the properties will be less effective.

A minimum amount of 25 parts or more of the organic solvent is required, but the amount can be increased as desired depending on the need for dilution.

[Effect]

In the temperature-sensitive element of the present invention, a cross-linked polymer monomer is first grafted onto graphite in the process of sequentially mixing with the above-mentioned ingredients,
It is formed by mixing the monomer with a linear polymer compound. During the heat treatment process, this polymer is twisted and blended simultaneously with the polymerization reaction of the crosslinked polymer. This can be determined from the homogeneity of the device product. In addition, it plays an extremely important role in providing flexibility to device products and stabilizing the properties in relation to the three-dimensionalization and degree of polymerization of crosslinked polymers.

In this way, linear polymer compounds provide flexibility and entropic rigidity to three-dimensional network compounds, which tend to be hard.
It provides flexibility at low temperatures, prevents it from becoming loose at high temperatures, and provides tightness to stabilize the entire system.

The low-molecular-weight organic compound appears to penetrate between the graphite layers directly or in cooperation with a reaction inducer, or expand the graphite layers, and is strongly adsorbed to the graphite layers to form a glabellar compound.

This means that the temperature sensing element of the present invention can be repeatedly heated at high temperatures (at temperatures much higher than the melting point of low molecular weight organic compounds, for example, melting point 6.
This is supported by experimental results showing that it can withstand temperatures up to 130°C (compared to a formulation at 5°C), with almost no change in properties.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

Note that parts of each component described in the following description represent parts by weight.

Example 1 Carbon black (average particle size O01μ or less) 45 parts Alkyd melamine resin monomer 55 parts Low paraffin (fine powder with average particle size 5μ or less) 25 parts High molecular weight polyethylene (powder with average particle size 15μ or less) 25 parts Toluene
45 part MEK
25 parts n-butanol
30 parts The mixed solution obtained by the above formulation is a black juice-like liquid, and when this is applied on a glass plate and reacted with far infrared rays at a temperature of 155°C for about 0 minutes, cracks will appear on the surface of the coating. It ended up being nothing.

The specimen is 60 cranes between poles x pole length 23mm, resistivity value 25°C.
It was 8.5xlOΩ- pieces.

This device was kept warm on the top and bottom of the device surface with alumina wool, and a voltage was applied. The element electrical resistance value immediately before voltage application is 13.
OKΩ, the element surface temperature was 25°C, but ACloo
When applied at V, the resistance value increases proportionally as the temperature rises.
It rose to Ω at 16.8. The temperature reached 62°C and was maintained at this temperature for more than 500 hours without any further increase in temperature.

Thereafter, when twice the power, that is, 14 tvAC was applied to the same test piece, the temperature of the heat generated remained at 75° C. for a long time, and there was no further temperature rise. The measured resistance of the device at this temperature had increased to 23.4 Ω.

Furthermore, when the voltage application to the element is cut and the temperature returns to room temperature of 25°0°C, the resistance of the element is completely 13. I returned to OKΩ. This was repeated 12 times and the results were exactly the same as above, confirming that the device with this formulation was a completely stabilized temperature-dependent self-temperature control device.

FIG. 1 is a graph showing the relationship between the element surface temperature and the resistance value when the applied voltage in mm to the temperature sensing element obtained in this example is changed.

FIG. 2 is a graph similarly showing the temperature increase characteristics, with the horizontal axis representing time (minutes) and the vertical axis representing temperature (°C).

Example 2 Carbon black (average particle size of 0.1 μ or less) Acrylic-epoxy resin monomer Ionomare resin n-paraffin (powder with average particle size of 5 μ or less) 15 parts 35 parts 15 parts 15 parts 25 parts A temperature-sensitive element was prepared in the same manner as in Example 1 using the above formulation. The specimen had a diameter of 60 squares between poles and a length of 23 poles, and had a specific resistance of 1.9 × 10Ω at 25°C.

Moreover, the temperature increase characteristics are shown in FIG. The stability of acrylic-epoxy resin increases as the degree of polymerization of the three-dimensional structure increases, but on the other hand, it is extremely unstable, which is a major drawback in practical use. This drawback is compensated for by ionic bonding ionomare resin.

Ionomare resin, as a thermoplastic elastomer, imparts flexibility to the entire device system while maintaining stability, especially at low temperatures near room temperature. It also has very good compatibility with acrylic-epoxy monomers and blends well.

Example 3 A temperature-sensitive element was prepared in the same manner as in Example 1, using alkyd melamine resin monomer as a crosslinked polymer as shown in the formulation table in Table 1, and changing the blending ratio with carbon black. The volume resistivity (Ω-cm+) at room temperature was measured.

Further, the volume resistivity (Ω-1) was measured when a phenol resin monomer and an acrylic-epoxy resin monomer were used as crosslinked polymers with the blending ratio of carbon black constant (45 parts).

For each measurement, the mixed solution was applied to a Pyrex glass plate (1 piece thick) in the same manner as in Example 1, and treated with far-infrared irradiation at an irradiation temperature of 155 "cxto minutes". I made a piece and went.

As shown in Figure 4, when an alkyne melamine resin monomer is used as a crosslinked polymer, when the amount of carbon blank exceeds 50 to 60 parts, the volume resistivity varies depending on the type of crosslinked polymer. It becomes approximately constant for each temperature sensing element.

〔Effect of the invention〕

As explained above, according to the present invention, there is extremely little change in resistance value over time even after repeated use, it has stable temperature-conductivity characteristics, there is no risk of local overheating, and it can be used as a sensor at the molecular level in various ways. A temperature sensing element with step self temperature sensing and control functionality can be provided.

In addition, this temperature-sensitive element has the properties of a flexible elastomer that is flexible and elastic even when the temperature rises, and has appropriate rigidity, so it can be processed into various forms, and the manufacturing method is easy and low cost. It can be manufactured with

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the element surface temperature and the resistance value when the applied voltage of the temperature-sensitive element obtained in Example 1 is changed. FIG. 2 is a graph showing the temperature increase characteristics same as above. FIG. 3 is a graph showing the temperature rise characteristics of the temperature sensing element obtained in the same Example 2. FIG. 4 is a graph showing the relationship between the blending ratio of alkyd melamine resin and carbon black and volume resistivity (at room temperature) for Example 3.

Claims (1)

[Claims] An organic temperature-sensitive element with self-temperature control characteristics, which is made by combining graphite or carbon black with a low-dimensional material mainly consisting of a cross-linked polymer and a linear polymer.