JPS62279603A - Polymer positive temperature characteristics resistance element - 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] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention provides that when the electrical resistance value reaches a certain temperature range,
The property that the positive temperature coefficient increases rapidly (positive temperature coefficient characteristic)
The present invention relates to a polymer positive temperature characteristic resistor having the following characteristics.

More specifically, the present invention is directed to a stable quality polymer positive temperature coefficient with excellent positive temperature coefficient characteristics and less variation in resistance value, which is useful as a material for, for example, overcurrent protection elements and self-temperature control heating elements. This relates to characteristic resistors.

[Conventional technology]

Conventionally, materials having positive temperature coefficient characteristics have been produced using various methods, such as a method of mixing carbon powder with a particle size within a specific range into a crystalline polymer (Japanese Patent Publication No. 33707/1983), and a method of mixing the carbon powder with a crystalline polymer. Thereafter, a method of crosslinking a crystalline polymer (Japanese Patent Publication No. 10352/1983) or a method of mixing a carbon blank with a specific particle size into a crystalline polymer so that the gel fraction falls within a specific range. A method of crosslinking the crystalline polymer (Japanese Unexamined Patent Publication No. 80201/1983) is known.

However, these materials are usually obtained by kneading a crystalline polymer and a conductive filler in a kneading machine such as a Banbury mixer, but materials obtained by such a mixing method are particularly difficult to obtain. When the resistivity is 10 Ω-cm or more, there is a problem that the resistivity value varies greatly within the same batch, and even if the same operation is repeated, the resistivity value varies greatly between lofts. are doing.

[Problem that the invention seeks to solve]

The present invention solves the problems with conventional materials having positive temperature coefficient characteristics, and provides a polymer positive temperature coefficient resistor with excellent positive temperature coefficient characteristics and stable quality with less variation in resistance value. It's about doing.

(Means for Solving the Problems) The present inventors have conducted extensive research to develop a polymer resistor with excellent positive temperature coefficient characteristics and stable quality. and in the presence of a specific polymerization catalyst,
It was discovered that the conductive filler is extremely uniformly dispersed in a product made by polymerizing ethylene, and the molded product is suitable for the above-mentioned purpose, and based on this knowledge, the present invention was completed.

That is, the present invention involves polymerizing ethylene in the presence of a polymerization catalyst consisting of (A) a K-conductive filler, (B) (a) a catalyst component containing a transition metal, and (b) an organoaluminum compound. A polymer positive temperature characteristic resistor is provided by molding a polyethylene resin composition containing 10 to 70% by volume of the obtained conductive filler.

Examples of the conductive filler used in the polyethylene resin composition of the present invention include thermal blank, furnace black, carbon black such as acetylene black, graphite, metal powder, pulverized carbon fiber, silicon carbide powder, and boron carbide powder. Can be mentioned. Among these conductive fillers, carbon black has an average particle size of 0.
Preferably it is less than 0.08 μm, preferably less than 0.076 μm. If the average particle size is 0.08 μm or more, the resulting resistor will have a large resistance value at room temperature, which is not preferable. Moreover, silicon carbide having a thickness of 0.5 to 100 μm is suitable.

The catalyst component (a) used in the production of the polyethylene resin composition can be prepared by various methods. Regarding the catalyst component containing a transition metal, the general formula % formula % (1) (where M is Titanium, vanadium, zirconium, or hafnium, and R1, RZ, and R:l have 1 to 1 carbon atoms.
It can be prepared by adding a transition metal compound represented by the following (10 alkyl groups, alkoxy groups, acyl groups, cyclopentadienyl groups, halogen atoms, or hydrogen atoms) and reacting them. At this time, the amount of the transition metal compound to be added is particularly: h11 Although there is no limit, it is usually per mole of the above-mentioned magnesium or manganese higher fatty acid salt, higher alcohol salt, or phosphate having a long-chain aliphatic hydrocarbon group. 0.5 mol or less, preferably 0.02 mol
-0.2 mol. If the amount of the transition metal compound added exceeds 0.5 mol, the catalytic activity will drop significantly, which is not preferable.

Here, the higher fatty acid or higher alcohol constituting the salt may be either saturated or unsaturated as long as it has 10 or more carbon atoms (although those with 16 or more carbon atoms are particularly preferred. Specific examples of these) Examples include higher fatty acids such as capric acid, lauric acid, myristic acid, balmitic acid, stearic acid, and oleic acid, and higher alcohols such as decanol, lauryl alcohol, myristyl alcohol, heptyl alcohol, and stearyl alcohol. In addition, as the phosphoric acid diamine constituting the phosphate having a long-chain aliphatic hydrocarbon group, mono- or dialkyl esters of phosphoric acid or phosphorous acid (R
OPHz ○3, (R○)2P○2, ROP H20
2), mono- or dialkyl phosphoric acid or phosphorous acid (RPH20-s, R2PH02, RPH20□
etc.). The long-chain aliphatic hydrocarbon group refers to a saturated or unsaturated aliphatic hydrocarbon group having 6 or more carbon atoms, preferably 8 or more, such as hexyl, heptyl, octyl, Examples thereof include 2-ethyl-hexyl group, nonyl group, decyl group, lauryl group, myristyl group, valmityl group, stearyl group, and oleyl group.

These higher fatty acids, higher alcohols, or magnesium salts and manganese salts of phosphoric acid having long-chain aliphatic hydrocarbon groups may be produced by known methods, or commercially available products may be dried and used as they are, or It may also form a double salt with other metals.

On the other hand, examples of the transition metal compound represented by the general formula (1) include T i C14, T i B r4, Ti
Ti (○CH,
3) C1i, Ti (OCz Hs)C13,'
l'i (QC3R7)CI3, Ti (OCi
Hq ) CI, , Ti(OCz Hs )Br,
trihalogenomonoalkoxytitanium such as Ti(○C
H:1)2C1z, Ti (QC2R5)z C1
□, Ti (QC3H?)2 CLz, Ti (QC4
)(9)2 C1z, Ti(QC2R5) z B r
Dihalogenodialkoxy titanium, such as T i
(OCH3) 3Cl, Ti (OCz Hs)3
C1, Ti (QC:l H?)3C1, Ti
(QC489)! CI, Ti (QCzHs)3
Monohalogenotrialkoxytitanium such as Br, Ti (
QCHs) 4, T i (OC2Hs) 4, T
i (OCi R7)4, Ti (QC4R7)4
Tetraalkoxytitanium such as (cp)z T
iCIz ((cp) represents a cyclohentadienyl group], (CT)) z (CH:l) z Cyclopentadienyl titanium compounds such as Ti, and VC
l4, voct, , VO(cz R5)3, VO
Vanadium compounds such as (OCa Hq) 3, (C
p) z Z r C12, (C1))2 (CH3
) Zirconium compounds such as 2Zr, (Cp)zHfC
I□, (CI))! Examples include hafnium compounds such as (CH3) 2 Hf.

As mentioned above, the transition metal-containing catalyst component in component (a) is a magnesium or manganese higher fatty acid salt, a higher alcohol salt, or a phosphate having a long-chain aliphatic hydrocarbon group, which has the general formula ( It can be obtained by reacting the transition metal compounds represented by 1), but the reaction conditions at this time include, for example, reacting these compounds at a temperature of 50°C or more to the boiling point of the solvent for 10 minutes or more. Bye. Of course, the conditions are not limited to these, and various other conditions can also be used. In addition, after mixing the above-mentioned higher fatty acid salt, higher alcohol salt, or phosphate having a long-chain aliphatic hydrocarbon group and the conductive filler in a hydrocarbon solvent, the transition metal compound is added and reacted. A catalyst component containing a transition metal may be prepared by. Furthermore, in this case, in order to obtain a catalyst component containing titanium, in addition to the above-mentioned salt and titanium compound, ■○C1ff, ■○(OCz R5), , VO
The use of vanadium compounds such as (OC4R9)'s is effective in expanding the molecular weight distribution and improving copolymerizability of the resulting polymer. Further, these transition metal-containing catalyst components may be supported on a fine carrier such as magnesium dichloride or magnesium jetoxide.

On the other hand, among the catalyst components (i), examples of catalyst components containing zirconium include cyclopentadienyl zirconium compounds and compounds obtained by reacting this with aluminoxane obtained by the above-mentioned known method. Examples of the cyclopentadienyl zirconium compound include dicyclopentadienyl zirconium, dimethyldicyclopentadienyl zirconium, and the like.

In addition, when these cyclopentadienyl zirconium compounds or the cyclopentadienyl titanium compounds and aluminoxane are used in combination, these compounds may be mixed with aromatic hydrocarbons such as henzene, toluene, xylene, and other alkyl henzenes. system? It is preferable to mix in a medium. Aliphatic hydrocarbon and alicyclic hydrocarbon solvents are not preferred because they cannot sufficiently dissolve the transition metal compound and aluminoxane. In addition, when the conductive filler is treated with the catalyst component (a), the reaction of these compounds is preferably carried out before mixing the filler, but it is preferable to carry out the reaction by mixing the filler at the same time. It is also possible.

The transition metal-containing catalyst component thus obtained is soluble in any hydrocarbon solvent such as an aliphatic hydrocarbon, an alicyclic hydrocarbon, or an aromatic hydrocarbon.

In the present invention, in the low-pressure polymerization of ethylene using the catalyst component (a) and the residual aluminum compound as the component (co), polyethylene is It is preferable to use a compound having a high activity capable of producing +r or more. this(
b) If the activity of the catalyst component is low, a large amount of the catalyst component must be added to the reaction system, and as a result, a deashing step is required after the polymerization reaction, making the post-treatment extremely complicated, which is undesirable.

In the present invention, (A) a conductive filler and (B) (
(b) Ethylene is polymerized in the presence of a polymerization catalyst consisting of the catalyst component and (b) an organoaluminum compound, but the conductive filler is pretreated with the catalyst component (a),
It is preferable to polymerize ethylene in the presence of the conductive filler provided with the catalyst component and (b) the organoaluminum compound.

The conductive filler is sufficiently dried by heating under reduced pressure or azeotropic drying using a solvent before being treated with the catalyst component. For 1 gram atom of the transition metal in the catalyst component,
An organoaluminum compound of 20 g atoms or less in terms of aluminum, for example 50'c or less, preferably 20°C
It is desirable to carry out the treatment at the following temperature for about 1 to 5 hours. Such treatment effectively prevents a decrease in the activity of the catalyst component due to moisture and functional groups in the filler.

Further, the organoaluminum compound used in this treatment may be the same as the organoaluminum compound used as the component (b) or may be different. monochloride, diethylaluminum monochloride,
Examples include dialkylaluminum monohalides such as diisobutylaluminum monochloride, alkylaluminum cybarides such as ethylaluminum diccolide and isobutylaluminum dichloride, alkylaluminum sesquihalides such as ethylaluminum sesquichloride, trialkylaluminum, and mixtures thereof.

Various methods can be used to treat the conductive filler with the catalyst component (a). for example(
A hydrocarbon containing the catalyst component of b)? 8 liquid, add the filler as it is or! The filler may be added as a suspension, thoroughly mixed, and then aged for the required time, or conversely, the filler may be added to a hydrocarbon solvent to form a suspension, and the hydrocarbon containing the catalyst component (a) After adding the solution and mixing thoroughly, the mixture may be aged for a required period of time. The solvent used in this treatment is appropriately selected from aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and the like. Further, the treatment temperature can be arbitrarily selected within the range of room temperature to the boiling point of the solvent used, and a) the formation time is usually 1 hour or more at room temperature, and the higher the temperature, the shorter the time may be.

Furthermore, in the above treatment, the ratio of the conductive filler to the catalyst component (a) varies depending on various conditions and cannot be unambiguously determined, but generally the ethylene polymerization reaction proceeds efficiently. In addition, if a certain amount of the catalyst component (a) is used so that a deashing step is not required after the reaction, and a filler is used in an amount such that the content of the conductive filler in the resulting resistor is 10 to b. good.

The conductive filler thus treated with the catalyst component (a) may be introduced into the reaction system in the form of a slurry, or may be introduced after separating the solvent.

As a result, the polymer is formed on the surface of the conductive filler during polymerization of ethylene, thereby increasing the adhesion between the polymer and the filler and providing a resistor with good filler dispersibility.

Next, there are no particular restrictions on the organoaluminum compound that is component (B) of the polymerization catalyst (B), but it usually has the general formula % () (R' in the formula has 1 to 10 carbon atoms, preferably is a 1-6 alkyl group, cycloalkyl group or aryl group, X' is a halogen atom, m is a number of 3 or less, specifically 1.1.5
．． Specific examples of this organoaluminum compound (2 or 3) include trialkylaluminum such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, and trioctylaluminum, diethylaluminum monochloride, diethylaluminum monopromide, dialkylaluminum monohalides such as diethylamminium monoiodide, diisopropylaluminum monochloride, diisobutylaluminum monochloride, dioctylaluminum monochloride, alkylaluminum cybarides such as ethylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum dichloride, isobutylaluminum dichloride, Alkylaluminum sesquihalides such as methylaluminum sesquichloride, ethylaluminum sesquichloride, ethylaluminum sesquipromide, butylaluminum sesquichloride, and mixtures thereof are preferably mentioned. In particular, mixtures of trialkylaluminium and dialkylaluminium monohalide and mixtures of alkylaluminum civalide and alkylaluminum sesquihalide are suitable when the catalyst component (a) containing titanium is used.

In addition, organolithium aluminum compounds and alkyl group-containing aluminoxane produced from trialkylaluminum and water can also be used. In particular, this aluminoxane is suitable when (a) one containing a cyclopentadienyl titanium compound, a cyclopentadienyl zirconium compound, etc. is used as the catalyst component.

In the present invention, (a) and (b) are used as polymerization catalysts.
There are no particular restrictions on the ratio of these components used, and they may be adjusted as appropriate depending on the conditions, but usually (a) (b) is used per 1 gram atom of the transition metal in the catalyst component. ) The amount of aluminum atoms in the component is 2 to 20
It is desirable to use a proportion of 0.00 gram atoms, preferably 10 to 1000 gram atoms.

In the present invention, ethylene is polymerized in the presence of (A) an x-conductive filler and (B) a polymerization catalyst consisting of the components (a) and (b) above, but within a range that does not impair the purpose of the present invention. In addition to ethylene, small amounts of other α-olefins such as propylene, butene-1, hexene-1, octene-1, etc.
1,4-methylpentene-1, decene, octadecene, etc. can also be copolymerized.

There are no particular limitations on the polymerization method and conditions, and either slurry polymerization or gas phase polymerization is possible, and both continuous polymerization and discontinuous polymerization are possible. Usually, the ethylene pressure in the reaction system is selected from normal pressure to 50 kg/cnl, and the reaction temperature is selected from 20 to 100°C, preferably from 50 to 90°C. Molecular weight adjustment during polymerization is carried out by known means,
For example, hydrogen can be used. Regarding the molecular weight of the polymer, a weight average molecular weight of approximately 50,000 to 400,000 is suitable.

In the present invention, powders such as alumina, mica, magnesium oxide, clay, and talc are added to the reaction system as desired in order to uniformize the heat generation inside the resistor due to energization, and to prevent the polymerization of ethylene. You may go.

After the polymer reaction is carried out in this manner, for example, in the case of slurry polymerization, the polymer is taken out by means such as flashing or centrifugation, and the solvent is removed by further drying, and then this polyethylene resin composition is made into a publicly known polyethylene resin composition. The desired resistor can be obtained by molding it into a desired shape using the method described above. During this molding process, lubricants, antioxidants, various stabilizers, etc. may be added in the usual amounts as desired, or organic peroxides may be added as crosslinking agents to effect crosslinking. good.

Examples of crosslinking agent peroxides include benzoyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, t-butyl peroxide, 2.5-di(L-butyl peroxy)hexine-3 and the like. It is desirable to adjust the degree of crosslinking so that the gel fraction is in the range of 10 to 50 weight percent, preferably 15 to 40 weight percent, based on the polymer. This crosslinking provides even better positive temperature coefficient properties. Regarding the crosslinking conditions, the organic peroxide is usually added in a range of 0.1 to 3% by weight to the polymer, kneaded at a temperature of 145 to 200'C for about 0.5 to 5 minutes, and molded. A desired degree of crosslinking can sometimes be obtained by heating at a temperature of around 190° C. for about 5 to 15 minutes, but of course the conditions are not limited to these.

In addition to the method using an organic peroxide, crosslinking can also be performed by, for example, a method using ozone or a method of irradiating active energy rays such as ultraviolet rays or electron beams.

When crosslinking is performed using ozone, for example, ozone 0.
After being exposed to a gas containing 5 to 20% by volume for about 0.5 to 8 hours, a crosslinking agent such as divinylbenzene is added to the polymer.
0.5 to 10 parts by weight, preferably 1 to 10 parts by weight
By adding 5 parts by weight and kneading, crosslinking progresses.

Further, when crosslinking is performed using an electron beam, the polymer may be irradiated with a dose of about 2 to 15 megarads.

The content of the conductive filler in the resistor thus obtained must be in the range of 10 to 70% by volume. If this amount is less than 10% by volume, sufficient conductive performance will not be obtained, while if it exceeds 70% by volume, positive temperature coefficient characteristics will not be sufficiently expressed.

EXAMPLES Next, the present invention will be explained in more detail by examples.
The present invention is not limited in any way by these examples.

Example 1 In a 500 ml flask purged with argon, 100 ml of dehydrated n-hebutane and 10.0 ml of magnesium stearate were added.
g (17 mmol) and titanium tetrachloride 0.33 g (1
, 7 mmol) was then heated and reacted under reflux for 2 hours to obtain a viscous solution of the titanium-containing catalyst component.

Next, n-
Hexane looml and well dried average particle size 43
20 g of mμ carbon black (manufactured by Mitsubishi Chemical Industries, Dia Black @E) was added, then 0.02 mmol of the titanium-containing catalyst component was added, and the carbon blank and catalyst component were treated at 40°C for 1 hour. A slurry-like contact treatment product was obtained.

Next, the entire amount of the contact treatment product was charged into 12 autoclaves purged with argon, and n-hexane was added to bring the total amount to 400 ml. Next, 1 portion each of triethylaluminum and diethylaluminum monochloride was added to this.
mmol was added, the temperature was raised to 90°C, hydrogen was supplied until the internal pressure reached 4 kg/crA-G, and ethylene was introduced continuously to maintain the total pressure at 9 kg/crA-G. The polymerization reaction was carried out for 40 minutes while supplying the solution. As a result, 80 g of a carbon blank-containing polyethylene composition was obtained. The composition ratio of this material is carbon bra 15° 1% by volume, polyethylene 84.9%.
It was % by volume.

30 g of the composition thus obtained was melted and kneaded for 3 minutes using a kneading roll at 180°C, and then a sheet was formed using a hot press molding machine.

Next, electrolytic nickel foil with a thickness of 20 AtL11 was bonded to both sides of this sheet by thermocompression to form a laminate with a thickness of 1 AtL1. From this laminate, 16 ICl11 square test pieces were cut out. For all these test pieces, the resistance value at 25"C between the nickel foils on the upper and lower surfaces was measured, and the value converted to specific resistance was within the range of 100 to 135 Ω-cm, and the average value was 120 Ω-cm. Met.

Furthermore, the resistance increase factor when the test piece was heated to 135°C was 106.0 times the value at 25°C.

Example 2 Instead of the carbon black used in Example 1, silicon carbide powder (manufactured by Fujimi Abrasives Industry ■, GC#2000) was used.
) 30 g of the same carbon blank 15 used in Example 1, treated in the same manner as in Example 1 with the titanium-containing catalyst component, and before introducing hydrogen in the autoclave.
60 g of a polyethylene composition was obtained in the same manner as in Example 1, except that 60 g of polyethylene composition was added. The composition ratio of this material is silicon carbide 28.4% by volume, carbon black 24.9% by volume,
The polyethylene content was 46.7% by volume.

Using 30 g of this polyethylene composition, 16 test pieces were prepared in the same manner as in Example 1, and the resistance value at 25°C was measured and the value converted to specific resistance was in the range of 91 to 100 Ω- side. The average value of these values was 96Ω-Ro. Furthermore, the resistance increase factor when this test piece was heated to 135°C was 10&0 times the value at 25°C.

Comparative Example 1 18.6 parts by volume of high-density polyethylene (manufactured by Idemitsu Petrochemicals NS, Idemitsu Polyethylene 440M) and 81.4 parts by volume of the carbon black used in Example 1 were mixed in a lab blast mill.
The mixture was kneaded at 70°C for 10 minutes.

Using this composition, 16 test pieces were prepared in the same manner as in Example 1, and the resistance value at 25°C was measured and converted into specific resistance, which was in the range of 75 to 165 Ω-cIn. The average value was 125 Ω-cm. Moreover, the resistance increase factor at 135°C was 10'·0 times the value at 25°C.

Comparative Example 2 High-density polyethylene (same as that used in Comparative Example 1) 5
3.7 parts by volume, 27.2 parts by volume of silicon carbide powder (same as that used in Example 2), and carbon black powder (
19.1 parts by volume (same as that used in Example 1) were kneaded for 10 minutes at 170° C. in a lab blast mill.

Using this composition, 16 test pieces were prepared in the same manner as in Example 1, and the resistance values at 25°C were measured and converted into specific resistances, which were in the range of 80 to 105 Ω-■. The average value was 92 ohms. Moreover, the resistance increase factor at 135°C was 106.5 times that at 25°C.

As can be seen by comparing Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2, the variation in the value converted into specific resistance is considerably larger in the Comparative Example than in the Example.

〔Effect of the invention〕

The polymer positive temperature coefficient resistor of the present invention not only has excellent positive temperature coefficient characteristics, as the rise multiplier of resistance value reaches 106, but also has stable quality with less variation in resistance value compared to conventional ones. For example, it is useful as a material for overcurrent protection elements, temperature detectors, self-temperature control heating elements, etc.

Claims (1)

[Claims] 1. Ethylene is polymerized in the presence of a polymerization catalyst consisting of (A) a conductive filler, (B) (a) a catalyst component containing a transition metal, and (b) an organoaluminum compound. A polymer positive temperature characteristic resistor is formed by molding a polyethylene resin composition containing 10 to 70% by volume of the conductive filler obtained in this manner. 2. The polyethylene resin composition includes (A) a conductive filler treated with (a) a catalyst component containing a transition metal;
(b) The polymer positive temperature characteristic resistor according to claim 1, which is obtained by polymerizing ethylene in the presence of an organoaluminum compound.