JPH08191003A - Manufacture of ptc resistor and resistor manufactured by it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method for producing a PTC resistor exhibiting low resistivity and high current conductivity at a high temperature. SOLUTION: A polymer is admixed with a filler composed of a material having high electric conductivity and a resistor is made of the mixture. A substance having high glass transition point, melting point or crosslinking point, where PTC transition takes place only at 140 deg.C or above, is selected as the polymer. An oxidation resistant substance harder than carbon black or silver is selected as the filler. The filler is stocked in a low pressure or a nonoxidative atmosphere, especially in a protective gas atmosphere, and/or fused chemically before being mixed. Improvement in the properties of a PTC resistor thus produced can be achieved when the polymer is hardened or annealed in at least two temperature stages of the process for molding the resistor body part W.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a method for manufacturing a PTC resistor according to the preamble of claim 1, a PTC resistor manufactured by the method and a particularly advantageous application of the PTC resistor.

[0002]

2. Description of the Related Art A method of manufacturing a resistor exhibiting PTC behavior is as follows.
For example, it is described in International Patent Application Publication No. 9,119,297. In that process polyolefins, especially polyethylene, polypropylene or polybutene, or other linear polymers such as polyamides, polyethylenes,
Powdered materials based on terephthalate, polybutene terephthalate or polyoxymethylene are used as powdered conductive substances such as carbon black, pure metals such as nickel, tungsten, molybdenum, cobalt, copper, silver or aluminum; alloys such as brass; Compounds such as ZrB ₂ or TiB ₂ , carbides such as TaC, W
C or ZrC, mixed with nitrides such as ZrN or TiN or oxides such as V ₂ O ₃ or TiO ₂ .
In this case, the polymer is up to at least 30% by volume of the resulting mixture and the conductive material is at least 20% by volume of the resulting mixture. Plates are made from this mixture at elevated temperature with the electrodes mounted on it. During the pressing process, the temperature is adjusted so that the polymer melts to at least a rough surface and then the plate is solidified to form a compact body with electrodes. This body is generally 30 ~
It has an initial resistivity of 50 mΩ · cm and is passed through a PTC transition stage at elevated temperatures, eg above 80 ° C. During this transition, the electrical resistivity increases significantly. This method is particularly suitable for producing PTC resistors based on thermoplastic polymers.

PTC containing a thermosetting polymer as a basic component
The method of manufacturing the resistor is described in T.W. R. “Composite PTCR themis” by Shrout et al.
tors utlising conducting
borides, silicides, and c
Arbides ”, J. of Material Sc
ience 26 (1991), 145-154. In this case, the epoxy resin is based on electrically conductive borides such as titanium boride, niobium boride or zirconium boride, carbides such as titanium carbide, or silicides such as niobium silicide, tungsten silicide or molybdenum silicide. Mix with the filler at room temperature, pour the resulting mixture in a mold and cure at about 80 ° C. to form the resistor body. The resistor body is then polished and electrodes are provided. Polysciences In
c. Marketed by the company under the name Spurrs,
The above boride, carbide or silicide resistor body has a resistance of 5 Ω at room temperature, depending on the type and proportion of filler.
An initial resistivity greater than cm is shown.

[0004]

Therefore, in a rational and practical way, PTC resistors are produced which exhibit a very low initial resistivity and a high rated current carrying capacity regardless of the nature of the polymer used. It is an object of the present invention to provide a new method of the above kind.

[0005]

The method of the present invention is characterized by method steps that are easy to carry out and that can be easily controlled by commonly available means. Optimal selection of polymer and filler and treatment not only significantly reduces the cold resistivity of PTC resistors produced by the method of the present invention compared to comparable sized resistors according to the prior art, but at the same time Also assures the high PTC transition temperature of the resistor. The high PTC transition temperature allows a relatively high operating temperature of the resistor. Since the cooling of the resistor due to free or forced convection is proportional to the difference between the working temperature and the ambient temperature, and because the cooling by radiation is proportional to the fourth power of the operating temperature, The resistors produced by the method can be loaded with a relatively high rated current without being heated to unacceptably high temperatures.

[0006]

DETAILED DESCRIPTION OF THE INVENTION Therefore, PTC resistors manufactured by the method of the present invention are of particular interest in power applications, and may be
Cold specific resistance smaller than Ω · cm and / or 10
It can be very advantageously used as a component showing a high current-conducting power at a temperature of 0 ° C or higher. This is especially the case when there is a swing in resistance. That is, room temperature ohmic resistance R _cold and PTC
The ratio with the ohmic resistance R _hot after the transition is at least 10 ⁸ as a result of the proper combination of polymer and filler and after carrying out the appropriate heat treatment steps, and even 10 ¹⁰ to 10 ¹² if appropriate. is there. At that time, a particularly high electric field strength can be maintained in the hot state. Particularly suitable for this purpose are in particular amorphous polymers, for example thermosetting resins based on epoxides. With proper selection of materials and treatments, such PTC resistors exhibit a very low initial resistivity. During curing, the epoxide shrinks and creates internal stresses that press the individual filler particles together while simultaneously reducing their contact resistance. The choice of hard filler particles causes the individual filler particles to separate rapidly from one another during heating of the resistor which results in the PTC transition as a result of the expansion of the polymer matrix and, consequently, in the case of relatively soft fillers. Particle binding, which is possible, is reliably avoided.

The process according to the invention can generally be carried out particularly advantageously if the following requirements are fulfilled: -Selection of a filler which is hard compared to the materials normally used, for example silver and / or carbon black. , It is difficult to select a filler that forms an insulating oxide, -manufacture and store the filler in a protective gas atmosphere, -chemically etch.
excluding any oxide film that may be present according to g), preferably selecting filler particles with an average diameter of more than 10 μm, preferably selecting the filler content to be greater than 30% by volume, and-high glass An epoxy resin having a glass transition temperature higher than the transition temperature, preferably 130 ° C. or a high melting point,
Thermoplastic resins preferably having a melting point above 140 ° C. or thermoplastic elastomers which preferably crosslink at temperatures above 140 ° C. or mutually penetrating nettings such as eg polyurethane copolymers.
copolymers that form a "working point", a so-called high melting point, preferably "inner penetrating network (i) above 140 ° C.
internetrating network) ”
Select (IPN).

Amorphous polymers, such as epoxides in particular, have proven to be particularly advantageous in the manufacture of PTC resistors for power applications. This shows that the PTC resistor having an epoxide as a basic component exhibits a significantly lower cold resistivity than the PTC resistor having a thermoplastic resin as a basic component. Eventually, the epoxide shrinks during curing and at that time produces internal stress. In this method, the conductive particles of the filler are squeezed together and under certain conditions the contact resistance between adjacent particles can be significantly reduced. An important condition in this context is that the individual particles are sufficiently stiff and the polymer matrix separates from each other when expanded, as a result of several heatings of the resistor--for example, when a short circuit current occurs. Only then does the PTC transition take place reliably and the binding of filler particles, as can be the case, for example, with relatively soft substances, for example silver, is reliably avoided. Amide-cured, especially dicyandiamide-cured or anhydride-cured epoxides have proved to be particularly advantageous as polymers. It is also possible to add one or more catalysts. Such polymers have relatively high glass transition temperatures and also have coefficients of thermal expansion greater than 10 ^-5 . Furthermore, in the case of a thermosetting resin, the dimensional stability of the PTC resistor guarantees a PTC transition temperature or higher.

Besides such epoxides, high temperature thermoplastics are also suitable as polymers. A thermoplastic resin having a particularly large crystalline component, eg, a melting point (T _m ) of about 165 ° C.
Polypropylene, thermoplastic polyurethane (TPU; T
_m = about 120 to 200 ° C.), polybutene-terephthalate (PBT; T _m = about 120 to 200 ° C.), polyethylene terephthalate (PET; T _m = about 255 ° C.), polyethylene-naphthalate (PEN; T _m = about 262)
C), polyphenylene sulfide (PPS; _Tm = about 288 C), syndiotactic polystyrene (s-).
PS; T _m = about 263 ° C.), polyether-ether ketone (PEEK; T _m = about 334 ° C.), polyaryl-
Ether ketone (PAEK; T _m = about 380 ° C.), polybenzimidazole (PBI; T _m = about 700 ° C.), fluorinated synthetic resin (T _m = up to 330 ° C.), thermoplastic polyimide (TPI; T _m = about 700 ° C.) 406 ° C.) or copolymers or mixtures thereof can be used.

If high temperature thermoplastics are used, the process of the invention advantageously comprises one of the following process steps: Mixing the filler with the hot thermoplastic using a kneader. Or-the filler is mixed in the dry state with a powder of a thermoplastic material, or-the thermoplastic is polymerized on the surface of the filler particles or mixed with the filler while being dissolved in a solvent and then the mixture is frozen- Or spray dry.

The material obtained from this is hot pressed in a mold.
Or by injection molding. Place of polymer
To achieve the desired high degree of crystallinity, this material should be
Anneal underneath. Especially high dimension
Legal stability depends on thermal, chemical or radiation crosslinking
Therefore, it can be achieved. Particularly suitable filler (single
(Alone or a mixture) is generally a metal boride such as TiB ₂
Or ZrB₂, Metal carbides such as TiC or V
C, metal nitride such as TiN, metal oxide such as R
uO₂, And / or metal silicides such as MoSi₂
Or WSi₂And / or metals, such as Mo in particular,
Ni and / or W. The filler is fixed-and
It may be hollow particles. However, this is
Particles having an a / shell structure may be used, in which case
The above-mentioned boride, carbide, nitride, oxide and / or
Or made of silicide and the core is especially a non-alloy metal, eg
For example, Ni, W, Ti, Zr, Mo, Co or Al;
Oxidation based on gold, eg brass; or Ti or V
Objects, especially TiO, V₂O₃Or VO.

[0012] Particularly advantageous embodiments of the invention and other advantages achievable therewith are explained in more detail below with reference to the drawings. For a better understanding of the invention and of the many advantages associated with it, a detailed description is given below with the aid of the accompanying drawings, which show, in a simplified form, experimental embodiments of the invention: FIG. Figure 3 shows a perspective view of a PTC resistor made of a polymer matrix and comprising conductive filler particles filled therein. FIG. 2 shows a resistivity [Ω · cm] of the PTC resistor (1) manufactured by the method of the present invention and a comparative resistor having epoxide (8) and thermoplastic resin (15, 16) as basic components. It is a graph which shows it as a function of temperature [° C]. FIG. 3 shows two PTC resistors (4, 9) manufactured by the method of the present invention.
And the resistivity [Ω · cm] of the comparative resistors (3, 8, 14) each of which has epoxide as a basic component, the temperature [° C]
10 illustrates a graph shown as a function of. FIG. 4 is a graph of 3 manufactured by the method of the present invention and manufactured under different process conditions.
Resistivity of one PTC resistor (5, 6, 7) [Ω · cm]
Figure 6 illustrates a graph showing as a function of temperature [° C].
FIG. 5 is a graph showing the resistivity ρ [Ω · cm] of two PTC resistors (10, 11) manufactured by the method of the present invention and having a thermoplastic polymer as a basic component as a function of temperature [° C.]. Shows. FIG. 6 shows the initial resistivity [Ω · cm] of four PTC resistor groups I, II, III and IV, each of which has an epoxide or a thermoplastic resin as a basic component and the same filler component as the average diameter of the filler particles. Figure 9 illustrates a graph showing as a function. FIG. 7 is a graph showing the resistivity ρ [Ω · cm] of a PTC resistor having a high temperature thermoplastic resin as a basic component as a function of temperature [° C.].

Next, a description will be given with reference to the drawings. FIG. 1 shows a resistance body part w arranged between ^two terminal electrodes e ¹ and e ^2.
2 shows a PTC resistor having The resistance body part w
Is generally composed of a material exhibiting a relatively low initial resistivity of a few mΩ · cm and has a relatively large length in the range of centimeters compared to its cutting area of, for example, a few square centimeters. have. Its resistance excursion is greater than 10 ⁸ and is typically 10 ¹⁰ to 10 ¹² . The above-mentioned properties make it possible, despite its long distance, to still carry a relatively high current density during continuous loading and to withstand high voltages without difficulty in a high resistance state after a PTC transition. It is advantageous for use in power applications in the voltage range of kV. The resistance body part w also generally exhibits a PTC transition temperature higher than 130 ° C. This allows a relatively high operating temperature of the resistor. This resistor is acceptable because the cooling of the resistor by free or forced convection is proportional to the difference between the working temperature and the ambient temperature and also because the cooling by radiation is proportional to the fourth power of the working temperature. It can be loaded with a relatively high rated current without heating to an unacceptably high temperature.

It is possible to manufacture this resistor particularly advantageously.
The following describes how to do this: exclusively under reduced pressure or not.
Oxidizing atmosphere, especially protective gas such as nitrogen or argon
Stored in an atmosphere and / or chemically eroded
Conductive powder filler is added to the epoxide base in a mixer.
Mix uniformly with the liquid resin that is the main component. During subsequent processing
In order to prevent sedimentation of the resin to high temperatures, eg 5
Partially gel during processing at elevated temperatures of 0-80 ° C.
After addition of hardener, especially dicyandiamide or acid anhydride
The resulting mixture can be poured into molds or injection molded.
So processed and cured at a temperature of 120-220 ° C
To form the resistance body portion w. Electrode e ¹, E²Is cured
After that, the resistor body is generally vapor-deposited on the polished end.
Or in some cases, in some cases these are cast and
It may already be incorporated into the resistor during subsequent curing.

In another experimental embodiment, a powdered conductive filler which has been previously stored under reduced pressure or in a non-oxidizing atmosphere, in particular a protective gas such as nitrogen or argon, and / or which has been chemically eroded. Is mixed with the powdered thermoplastic resin. The resulting mixture, along with the electrodes, is poured into a mold and compression molded at elevated temperature to form a resistor. The starting materials used, the temperature conditions during the curing of the epoxide,
The temperature and pressure conditions during processing of the thermoplastic resin and the physical properties of the PTC resistor produced by the method of the present invention,
For example, the PTC transition temperature, glass transition temperature and initial resistivity are shown in the two tables below and in Figures 2-5 and 7.

Example Polymer Filler Curing (annealing) ──────────────────────────────────── 1 Araldit ^{(R )} 66 vol% Ni at 140 ° C for 20 hours (approx. 60 μm, corroded) 2 Araldit ^(R) 29 vol% Ni / Ag 140 ° C for 20 hrs (20-80 μm, silver coating) 3 Araldit ^(R) 43 vol % TiB ₂ (100 to 200 140 ° C for 20 hours μm, corroded) 4 Araldit ^(R) 43% by volume TiB ₂ (63 to 100 140 ° C for 20 hours + 180 ° C μm, corroded) 2 hours 5 Epikote ^(R) 43% by volume TiB ₂ (100 to 200 at 160 ° C for 2 hours μm, corroded) 6 Epikote ^(R) 43% by volume TiB ₂ (100 to 200 at 160 ° C for 2 hours + 140 ° C, μm, 16 hours 7 Epikote ^(R) 43% by volume TiB ₂ (100-200 2 hours at 160 ° C + 140 ° C μm, corroded) 16 hours + 200 ° C 2 hours 8 Spurr ^(R) 43% by volume TiB ₂ (63~100 80 24 hours [mu] m at ^℃) 9 Spurr ^(R) 43% by volume of TiB ₂ (100 ~200 120 ℃ for 24 hours [mu] m,溶蝕already) 1 0 PPS 43% by volume TiB ₂ (<45 μm, 3 minutes at 300 ° C and 139 ablated) MPA 11 PPS 43% by volume TiB ₂ (<45 μm, 3 minutes at 300 ° C and ablated) Also at 139MPA at 260 ° C for 4 hours 12a PE 25% by volume TiB ₂ (100-200 μm, corroded) 12b is the same as 12a, but 30% by volume TiB ₂ 12c is the same as 12a, 35% by volume TiB ₂ 12d is the same as 12a, 40% by volume TiB ₂ 12e is the same as 12a, but 55% by volume TiB ₂ 14 Spurr ^(R) 43% by volume TiB ₂ (63 ~ 100 PE 24 h μm at 80 ° C, corroded) 15 PE 50 vol% TiB ₂ 16 PE carbon black (marketed by Raychem) 17 s-PS 50 vol% TiB ₂ (<45 μm, corroded) 18 PE 60 Volume% TiB ₂ (1-5 μm, ablated) Araldit ^(R) = cured polymer prepared by mixing Araldit F and HY 905 in a 1: 1 weight ratio Epikote ^(R) = Epikote 828, Epicure Curing polymer manufactured from MNA and HY 960 (Epoxy resin, curing agent and accelerator 100: 90: Shell's products mixed in a weight ratio) Spurr ^(R) = vinylcyclohexane - dioxide (VCD), diglycidyl ether of polypropylene glycol (Polyscience Inc PPS = polyphenylene-sulfide, PE = polyethylene, s-PS = syndiotactic-polystyrene Example PTC transition temperature [° C] glass transition temperature [° C] initial resistivity ─── ───────────────────────────────── 1 160 104 5 2-104 26 3 150 104 14 4 160 105 13.5 5 140 79 7 6 160 124 19 7 200 144 45 8 85 80 26 9 120 90 7 10 250 4 11 260 11 12a 130 85000 12b 130 460 12c 130 240 12d 130 30 12e 130 18 14 100 80 6 15 130 29 16 130 844 17 260 97 18 130 25 From the table and Fig. 2, it has a low initial resistivity and a high PTC.
PT showing transition temperature and resistance swing greater than 10 ^8.
It is clear that the C-resistor (Example 1) can be produced by selecting a suitable epoxide having a glass transition temperature above 100 ° C. and a suitably prepared pretreated filler of suitable hardness. For example epoxide and Ti
B ₂ (Example 8) or polyethylene and TiB ₂ (Example 15,
Compared to a PTC resistor of comparable size (based on the prior art) with Example 16) as the basis,
Such resistors exhibit a low initial resistivity and a high PTC transition temperature, which is advantageous for use in power applications. The importance of choosing a suitable filler is clear from Figure 2. Finally, if the selected filler is too soft (Example 2), binding of filler particles and PTC transitions no longer occur.

From the table and FIGS. 2, 3 and 4, it is clear that the PTC transition temperature of the PTC resistor produced by the method of the present invention is greatly increased by suitable heat treatment in some cases. Resistors treated in this way can be operated at high operating temperatures and consequently have a higher rated current carrying capacity than resistors that have not been heat treated. Suitable heat treatments are standard curing temperatures (eg 3, 5, 8, 14)
Are generally cured or pre-cured at elevated temperatures (Examples 4, 7, 9) for several hours, but may be pre-cured at relatively low temperatures for several hours (Example 6). With a suitable choice of epoxide, a PTC transition temperature T _{c of} up to 200 ° C. can be achieved if the curing is carried out in a suitable manner. The initial resistivity ρ of heat-treated resistors is often significantly higher than that of untreated resistors. Properly manufactured resistors (eg 4, 6, 7) have a resistivity of less than 1 Ω · cm even at temperatures up to 150 ° C.
It can be used to conduct current in a device where temperatures of 0 ° to 150 ° C. occur over long periods of time.

Particularly high PTC transition temperatures can be achieved with certain thermoplastic polymers. From the table and FIGS. 5 and 7, it can be seen that a PTC transition temperature of at least 250 ° C. can be achieved with polyphenylene-sulfide (PPS) or syndiotactic-polystyrene (s-PS) as polymer and TiB ₂ as filler. Resistors made from such materials have a resistivity of 190-22
Since the resistance is less than 1 Ω · cm even at a temperature of 0 ° C., such a resistor can conduct a relatively high rated current. A suitable heat treatment (Example 11) is often 180-270.
The resistivity drops very markedly between ° C, resulting in a much higher rated current carrying capacity of the resistor at high temperatures compared to untreated resistors.

The current carrying capacity of a PTC resistor (Example 10) composed of PPS and TiB ₂ made according to the invention and having a substantially cubic shape (length: about 20 mm, cross section: about 30 mm ² ) is comparable. Compare with a prior art PTC resistor composed of PE and TiB ₂ having different dimensions (Example 15). In this comparison, the PTC resistor has water flowing directly over the PTC resistor at 65 ° C (20
L / min) Place in water bath (T = 65 ° C.). A constant current is passed through the resistor for about 6 minutes. If no PTC transition occurs during this drying time, increase the current and repeat the measurement cycle. As a measure of current carrying capacity, the value of the current is measured just before the PTC transition has occurred. This gives a current density of about 120 A / cm ² for the resistor of the present invention, but 50 A / c for the resistor of the prior art.
You can only get m ² .

In the case of PTC resistors according to Examples 12a-12e
If the content is higher than 30% by volume, the filler content is low.
The table shows that it is necessary to achieve the resistivity. Book
The same applies to all PTC resistors manufactured by the method of the invention.
The same applies. The average diameter of the filler particles is advantageously
Should be greater than 10 μm. Because one hand
In, good electrical initial conductivity is thus
Because it is achieved. This is four PTC resistors I
(Polyethylene and 50% by volume TiB ₂Based on
II, II (polyethylene and 35% by volume TiB)₂The basic
, III (Spurr^(R)Epoxide and 35 capacity
% TiB₂Based) and IV (with polyethylene
60% by volume TiB₂(Following Example 18 and following Example 18)
Electrical resistivity ρ (about 30 ° C) is large for filler particles
It is clear from FIG. 6 which is shown as a function of size ps.
It Particles larger than 60 μm or 100 μm respectively
Especially good initial electrical conductivity is achieved
It Good starting components are used in the production of the resistors according to the invention.
The size of the filler particles should be 5 to ensure process compatibility.
Limit to up to 00 μm, preferably up to 200 μm
Is advantageous. Filler particles are 100 μm and 200 μm
Or 63 μm and 100 μm or alternatively 32 μm
45 μm or in some cases between 10 and 32 μm
May exist as a fraction with a uniform particle size
Yes. Relatively low initial resistivity compared to even filler
With a relatively large volume ratio, such as 63 μm and 100 μm flat
An example of coarse particles with a uniform particle size and relatively small volume ratio
Achieved even with fine particles up to 10 μm
Is done.

Many variations of the present invention have been suggested based on the above teachings. Therefore, the invention included in the scope of the claims defining the invention, including those other than those specifically described herein, obviously belongs to the invention.

[Brief description of drawings]

FIG. 1 shows a perspective view of a PTC resistor manufactured by the method according to the invention and consisting of a polymer matrix and conductive filler particles filled therein.

FIG. 2 is a comparison of a PTC resistor (1) manufactured by the method of the present invention with a resistivity [Ω · cm] and an epoxide (8) and a thermoplastic resin (15, 16) as basic components. It is a graph which shows that of the resistor for use as a function of temperature [° C].

FIG. 3 shows two PTCs produced by the method of the present invention.
Resistivity of the resistors (4, 9) and comparative resistors (3, 8, 14) each having an epoxide as a basic component [Ω · c
FIG. 6 illustrates a graph showing m] as a function of temperature [° C.].

FIG. 4 shows three PTC resistors (5,6,7) manufactured according to the method of the present invention and manufactured under different process conditions.
FIG. 4 is a graph showing the resistivity [Ω · cm] as a function of temperature [° C.].

FIG. 5 shows two PTC resistors (10,1) made by the method of the invention and based on a thermoplastic polymer.
The graph showing the resistivity ρ [Ω · cm] of 1) as a function of temperature [° C.] is shown.

FIG. 6 is an initial resistivity [Ω · of four PTC resistor groups I, II, III, IV having an epoxide or a thermoplastic resin as a basic component and having the same filler component, respectively;
cm] as a function of the average diameter of the filler particles.

FIG. 7 is a PT containing a high temperature thermoplastic resin as a basic component.
FIG. 6 shows a graph showing the resistivity ρ [Ω · cm] of the C resistor as a function of temperature [° C.].

[Explanation of symbols]

e ¹ , e ² ... Terminal electrode w ... Resistor body

Claims (14)

[Claims] 1. A resistive body portion disposed between terminals, the body portion being composed of a composition having a polymer matrix and a powder filler filled in the polymer matrix and including a conductive material. In a method for producing a PTC resistor by mixing a polymer and a filler with each other and molding a resistance body portion from this mixture at a high temperature, a) a high glass such that a PTC transition occurs only at a temperature higher than 140 ° C. A method as described above, characterized in that a substance having a transition temperature, a melting point and a crosslinking temperature is selected as a polymer, and b) a substance harder than carbon black or silver and having a higher oxidation resistance is selected as a filler. . 2. The process according to claim 1, wherein the filler is stored under reduced pressure or under non-oxidizing conditions before mixing, in particular in a protective gas atmosphere and / or chemically eroded. 3. A method according to claim 1 or 2 in which the polymer is cured or annealed in at least two temperature steps during the formation of the resistive body. 4. An amide-cured or anhydride-cured thermosetting material based on an epoxide having a glass transition temperature higher than 100 ° C., a thermoplastic resin or copolymer having a melting point higher than 140 ° C. or higher than 140 ° C. A thermoplastic elastomer having a crosslinking temperature is selected as the polymer and a metal boride, a metal carbide, a metal nitride, a metal oxide and / or a metal silicide and / or a metal, especially Mo, Ni and / or W is selected as a filler. The method according to any one of claims 1 to 3, wherein 5. A resistive body portion disposed between the terminal electrodes, the body portion comprising a composition comprising a polymer matrix and a powder filler filled in the polymer matrix, and comprising a conductive material. In a PTC resistor in which a polymer and a filler are mixed with each other and the resistor body is molded from this mixture at high temperature: a) high glass transition temperature, melting point such that the PTC transition only occurs above 140 ° C. And a substance having a crosslinking temperature is selected as a polymer, and b) a substance harder than carbon black or silver and having a higher oxidation resistance is selected as a filler, the PTC resistor. 6. A filler content of at least 30 volumes
The PTC resistor according to claim 5, which is%. 7. The PTC resistor according to claim 6, wherein the average diameter of the filler particles is exclusively larger than 10 μm. 8. The PTC resistor according to claim 7, wherein the average diameter of the filler particles is smaller than 500 μm. 9. The filler particles have an average diameter of 60 to 20 exclusively.
The PTC resistor according to claim 8, which has a thickness of 0 μm. 10. The filler particles have an average diameter of 60 to 1 exclusively.
The PTC resistor according to claim 9, which has a thickness of 00 μm. 11. At least two fractions are provided, the first fraction of which contains particles smaller than 10 μm and the second fraction which contains particles larger than 60 μm and smaller than 200 μm.
The PTC resistor according to 0. 12. Metal borides such as TiB ₂ or Z.
rB ₂ , metal carbides such as TiC or VC, metal nitrides such as TiN, metal oxides such as RuO ₂ , and / or metal silicides such as MoSi ₂ or WS.
High temperature thermoplastics containing i ₂ and / or metals, such as Mo, Ni and / or W as fillers and containing amide-cured, especially dicyandiamide-cured or anhydride-cured epoxides and large crystalline components, especially Polypropylene, thermoplastic polyurethane (TPU), polybutene-terephthalate (PBT),
Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), syndiotactic polystyrene (s-P)
S), polyether-ether-ketone (PEEK),
12. Polyaryl-ether-ketone (PAEK), polybenzimidazole (PBI), fluorinated synthetic resin, thermoplastic polyimide (TPI) or copolymer or mixtures thereof are used as polymer. PTC resistor. 13. The filler is solid- and / or hollow particles and / or core / shell-structured particles,
Here, the shell is made of the above-mentioned borides, carbides, nitrides, oxides and / or silicides and the core is in particular a non-alloy metal, such as Ni, W, Ti, Zr, Mo, Co or Al; alloys, For example brass; or oxides based on Ti or V, eg TiO, V ₂ O ₃ or V, among others.
The PTC resistor according to claim 12, which is O. 14. An initial resistivity of less than 25 mΩ · cm and / or a high current carrying capacity at a temperature of 100 ° C. or higher and / or between the resistance in the cold conducting state and the resistance after the PTC transition has taken place. A method of using a resistor according to claim 5 as a component having an increase in resistance of at least 10 ⁸ , preferably 10 ¹⁰ .