JP2006085978A - Conductive resin composition and planar heating element using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive resin composition which has good molding performance, good flexibility, and moisture resistance, in which the connection of electrodes is easy, and which has with high reliability. <P>SOLUTION: The conductive resin composition contains a crystalline polyester resin (A) having a number average molecular weight of 5,000 or more and 50,000 or less and a melting point of 50°C or more, conductive impalpable powder (B), and a compound having a structure of -N=C=N-. It is preferable that the glass transition point temperature of the crystalline polyester (A) is 40°C or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive resin composition and a planar heating element produced using these molded products. More specifically, it has excellent flexibility, good adhesion of electrode material, high moisture resistance and heat resistance required for in-vehicle applications, etc., and also causes necking when molding T-die etc. The present invention provides an excellent conductive molded article having excellent physical properties such as excellent moldability and impact resistance.

  Conventionally, planar heating elements have been used for the purpose of snow melting in floor heating, snow melting on roofs, roads, parking lots, and the like. Examples of the planar heating element include those produced by printing conductive carbon paste on a PET film, those using a woven fabric using conductive carbon fibers, and those obtained by melting and kneading carbon black into polyolefin. There are advantages and disadvantages to these. For example, when a conductive carbon paste is printed on a PET film, a thin heating element can be obtained. However, since the conductive layer coating is 10 to 30 μm, the piercing property is weak, and since a PET film is used, 3 There are drawbacks such as weakness to deformation of dimensional shapes. In the case of using a woven fabric using conductive carbon fiber, the cost is high, and furthermore, the temperature dependence of the carbon fiber has a negative resistance value, that is, the resistance value decreases at a high temperature. There is a difficulty above. On the other hand, those prepared by melt-kneading carbon black with polyolefin can achieve a relatively thin thickness and good flexibility, but it is difficult to connect the electrode material, and in the case of molding with a T die, There is a demand for improvement due to insufficient film-forming properties such as necking. Moreover, although the electrically conductive composition using amorphous polyester resin is also proposed, there exists room for improvement in blocking property or heat resistance (for example, refer patent document 1).

  In addition, as a material having flexibility, a crystalline polyester elastomer can be mentioned. However, a material having good flexibility is particularly lacking in hydrolysis resistance and has not yet been put into practical use. Furthermore, there is a problem of necking in the extrusion processability of T-die and the like, and improvement is desired.

JP 2000-88672 A (Claims)

  An object of the present invention is to provide a highly reliable conductive molded article having good moldability, good flexibility, and high humidity resistance that can withstand in-vehicle use.

  As a result of intensive studies to achieve the above problems, the present inventors have reached the present invention. That is, this invention is the following conductive resin compositions.

(1) A crystalline polyester resin (A) having a number average molecular weight of 5,000 or more and 50,000 or less and a melting point of 50 ° C. or more, a conductive fine powder (B), and a compound having a structure of —N═C═N— (C A conductive resin composition comprising:

(2) The conductive resin composition according to (1), wherein the crystalline polyester (A) has a glass transition temperature of 40 ° C. or lower.

(3) The conductive resin according to (1) or (2), wherein the compound (C) is a polycarbodiimide containing at least two structures of -N = C = N- in one molecule. Composition.

(4) The conductive resin composition according to any one of (1) to (3), wherein at least one of the molecular ends of the compound (C) is an isocyanate group.

(5) The conductive resin composition according to any one of (1) to (4), wherein the conductive fine powder (B) is carbon black and / or graphite fine powder.

(6) A sheet-like or film-like molded article comprising the conductive resin composition according to any one of (1) to (5).

(7) A planar heating element in which at least one of metal foil, metal wire, and conductive paste is connected as an electrode material to both ends of the molded product according to (6).

  The conductive resin molded article of the present invention can provide an on-surface heating element having both good moldability and flexibility, and also having high moisture resistance. Moreover, T-die extrusion property is further improved by mix | blending a compound (C).

  The conductive resin composition of the present invention has a number average molecular weight of 5000 or more and 50000 or less, a crystalline polyester resin (A) having a melting point of 50 ° C. or more, a conductive fine powder (B), and —N═C═N—. And a compound (C) having the structure: and being kneaded in a molten state.

  The polyester resin used in the present invention needs to be crystalline. By crystallization after melt molding, even a polyester resin having a low glass transition temperature does not block, and a flexible characteristic like an elastomer can be obtained. The term “crystallinity” as used herein refers to using a differential scanning calorimeter (DSC) to raise the temperature from −100 ° C. to 300 ° C. at 20 ° C./min, then to −100 ° C. at 50 ° C./min, In this case, the melting peak is shown in either of the temperature rising processes in the temperature rising process at a temperature of 20 ° C./min from −100 ° C. to 300 ° C.

  Further, the crystalline polyester resin (A) used in the present invention has a number average molecular weight before molding of 5000 or more, preferably 10,000 or more. An upper limit is 50000 or less from the surface of a moldability, Preferably it is 40000 or less. When the number average molecular weight before molding is less than 50000, the viscosity is too low to deteriorate the extrusion moldability and film forming property, resulting in poor mechanical properties as a molded product. When molding is performed using a product having a number average molecular weight of more than 50000 before molding, the resin fluidity may be lowered and the moldability may be lowered, or a gel-like product may be generated.

  The melting point of the crystalline polyester resin (A) used in the present invention is preferably 50 ° C. or higher. More preferably, it is 90 ° C. or higher. On the other hand, the upper limit is not particularly limited, but is preferably less than 300 ° C. from the viewpoint of moldability. When the melting point is less than 50 ° C., heat resistance and blocking resistance tend to decrease.

  The preferred glass transition temperature of the crystalline polyester resin (A) used in the present invention is 40 ° C. or lower, more preferably 30 ° C. or lower, and most preferably 10 ° C. or lower. The lower limit is not particularly defined, but is preferably −80 ° C. or higher, more preferably −50 ° C. or higher. When the glass transition temperature exceeds 40 ° C., flexibility tends to be lost. If it is less than -80 degreeC, it exists in the tendency for blocking resistance and heat resistance to fall.

  The acid component in the crystalline polyester resin (A) used in the present invention preferably contains terephthalic acid as the aromatic dicarboxylic acid in order to impart crystallinity. The aliphatic dicarboxylic acid used for the purpose of imparting flexibility preferably includes adipic acid and sebacic acid.

  As aromatic dicarboxylic acids other than the above terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 2,2′-diphenyl Dicarboxylic acids such as 4,4′-diphenyl ether carboxylic acid can be used. As aliphatic dicarboxylic acids other than the above-mentioned adipic acid and sebacic acid, succinic acid, azelaic acid, decanoic acid, dodecenyl succinic acid, dimer acid and the like can be used. In addition, alicyclic rings such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, hydrogenated orthophthalic acid, etc. Group dicarboxylic acids can be used. Also, trifunctional or higher functional carboxylic acids such as trimellitic acid and polar group-containing dicarboxylic acids such as sodium salt of 5-sulfoisophthalic acid can be used.

  The glycol component in the crystalline polyester resin (A) used in the present invention is particularly preferably at least one of ethylene glycol, diethylene glycol, and 1,4-butanediol in order to impart crystallinity. Other glycols include propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl, 2-butyl-1,3-propanediol, neopentyl glycol, 1,2 -Butanediol, 1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-propanediol, 2,2,4-trimethyl-1,5-pentanediol, 1,6-hexanediol 1,9-nonanediol, 2-methyloctanediol, 1,10-decanediol, dipropylene glycol, neopentyl glycol ester of hydroxypivalic acid (HPN), dimer diol, 2,2,4-trimethyl-1, Aliphatic glycols such as 5-pentanediol, 1,4-cyclohexanedimethanol, Aromatic glycols such as licyclodecane dimethanol, ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, ethylene oxide adducts of bisphenol S, propylene oxide adducts of bisphenol S are used. it can.

  Furthermore, it is preferable to use polytetramethylene glycol for the purpose of imparting flexibility. Further, polyethylene glycol, polypropylene glycol or the like may be used. Furthermore, it is also preferable to post-add ε-caprolactone after polymerization of the polyester resin to obtain a block copolymer.

  In addition, trivalent or higher polyols such as trimethylolpropane and pentaerythritol can be copolymerized in a small amount.

  Extrusion characteristics tend to be improved by copolymerizing a small amount of the above-described trivalent or higher polycarboxylic acid and / or polyol.

The acid value of the polyester resin used in the present invention is preferably 100 equivalents / 10 ⁶ g or less, more preferably 50 equivalents / 10 ⁶ g or less, and still more preferably 40 equivalents / 10 ⁶ g or less. On the other hand, the lower the lower limit, the better. When the acid value exceeds 100 equivalents / 10 ⁶ g, hydrolysis may be further promoted during extrusion processing, and the mechanical strength of the finished molded product may be lowered. Further, as the decomposition of the resin proceeds, the moldability such as resin sag during processing may be deteriorated.

  As the conductive fine powder (B), conventionally known flaky silver powder, spherical silver powder, three-dimensional higher order silver powder, dendritic silver powder, graphite fine powder, carbon black, nickel powder, copper powder, gold powder, palladium powder , Aluminum powder, indium powder and the like. Among these, preferable conductive fillers include flaky silver powder, graphite powder, and carbon black. In addition, a small amount of non-conductive filler such as silica powder, fumed silica, colloidal silica, talc, and barium sulfate may be blended for the purpose of adjusting the viscosity of the melt.

  When the conductive resin molding of the present invention is used as a heating element, it is preferable to blend carbon black and / or fine graphite powder at 30% by weight or less, more preferably 20% by weight with respect to 100% by weight of the resin. It is as follows. The lower limit is preferably 1% by weight or more. If it exceeds 30% by weight, the molded product becomes brittle or the resistance value tends to be too low. If it is less than 1% by weight, the resistance value tends to be too high.

  When the conductive resin molded product of the present invention is used with a planar heating element for floor heating or the like, the calorific value is preferably 0.1 W or more, more preferably 1 W or more. The upper limit is preferably 50 W or less, more preferably 10 W or less. When a 100V or 200V power supply is used, the circuit resistance is preferably 0.1 kΩ or more, more preferably 1 kΩ or more. The upper limit is preferably 50 kΩ or less, more preferably 10 kΩ or less.

  Assuming a heating element having a general length of 50 to 100 cm and a width of 5 to 20 cm, the sheet resistance is preferably 1 Ω / □ or more, more preferably 10 Ω / □ or more in order to satisfy the above conditions. is there. The upper limit is preferably 10 kΩ / □ or less, more preferably 1 kΩ / □ or less. If the sheet resistance is less than 1 Ω / □, current may flow too much and the temperature may rise too much. Further, if it exceeds 10 kΩ / □, there is a possibility that sufficient heat generation cannot be obtained. Of course, if the voltage to be used and the application are changed, the preferable range changes from the above range.

  In the conductive resin composition of the present invention, it is preferable to blend the crystalline polyester resin (A) with a compound (C) having a structure of -N = C = N- before the molding. Since the compound (C) having a structure of -N = C = N- reacts with the carboxyl group (acid value) contained in the polyester resin in the melt-kneading process, it prevents hydrolysis of the polyester resin and increases at a low shear rate. There is a sticky effect, and the moldability by T-die is improved.

  Although it does not specifically limit as a compound (C) which has a structure of -N = C = N- used for the conductive resin composition of this invention, Bis (dipropylphenyl) carbodiimide, dicyclohexyl carbodiimide, diisopropyl carbodiimide, dimethyl carbodiimide , Diisobutylcarbodiimide, di-t-butylcarbodiimide, dioctylcarbodiimide, diphenylcarbodiimide, di-β-naphthylcarbodiimide, monocarbodiimide such as t-butylisopropylcarbodiimide, two structures of —N═C═N— in one molecule Examples thereof include polycarbodiimide having the above, monocarbodiimide having an isocyanate group at the terminal, and polycarbodiimide having an isocyanate group at the terminal.

  As the polycarbodiimide, known ones prepared by decarbonation of diisocyanate compounds can be used (US Pat. No. 2,941,956, Japanese Examined Patent Publication No. 47-3279, J. Org. Chem., 28, 2069-2075 (1963). ), Chemical Review 1981, Vol. 81, No. 4, 619-621). Specifically, as the diisocyanate, 4,4-diphenylmethane diisocyanate, 4,4-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6- Tolylene diisocyanate, 1,5-naphthylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate alone or in combination The above can be copolymerized and used. Further, the degree of polymerization may be controlled by reacting the terminal isocyanate, or the terminal isocyanate may be blocked. As end-capping agents, monoisocyanate compounds such as phenyl isocyanate, tris isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate, -OH group, -COOH group, -SH group, -NH-R (R is hydrogen) A compound having an atom or an alkyl group) can be used.

  Moreover, if it consists of these structures, either a thermoplastic type or a thermosetting type may be sufficient. Of these, polycarbodiimide is preferable from the viewpoints of thermal stability, bleed resistance, safety, workability, and the like. Furthermore, polycarbodiimide having an isocyanate group at the terminal is preferable in terms of both adhesiveness and hydrolysis resistance. The isocyanate group reacts preferentially with the terminal hydroxyl group of the polyester and enhances the adhesion with a metal, a polyester film or the like by forming a urethane bond. In addition, the molecular weight is improved by the chain extension effect of the polyester, and there is also an effect of delaying the occurrence of the deterioration of mechanical properties due to hydrolysis.

In the compound (C) having a structure of —N═C═N—, the —N═C═N— group equivalent is preferably 150 to 350 g / equivalent, and more preferably 200 to 300 g / equivalent. When the —N═C═N— group equivalent is 350 g / equivalent or more, it is necessary to add a large amount of the compound (B) to be added in order to impart adhesion, hydrolysis resistance and film-forming property. Arise.
As the compound (B) having a structure of —N═C═N—, commercially available products such as Stabuzosol manufactured by Rhein Chemie, Carbolite manufactured by Nisshinbo Co., Ltd. and Cosmonate LK manufactured by Mitsui Takeda Chemical , Cosmonate LL, Lupranate MM-103 made of BASF INOAC polyurethane, and the like.

  The compounding amount of the compound (C) having a structure of —N═C═N— is preferably 0.1 to 20 parts by weight when the crystalline polyester (A) of the present invention is 100 parts by weight. When the compound (C) is 20 parts by weight or more, the mechanical properties may be inferior and the adhesiveness and heat resistance may be lowered. Moreover, when it is less than 0.1 part by weight, the amount of —N═C═N— in the adhesive composition is reduced, and the effect of improving hydrolysis resistance and the effect of improving film forming in a T-die may be inferior. is there.

  As described above, the compound (C) having a structure of -N = C = N- exhibits an effect by reacting with the carboxyl group of the polyester resin. Therefore, the crystalline polyester resin (A) of the present invention and the compound (C ) Is preferably taken.

  As the step of reacting positively, it is preferable to react the crystalline polyester resin (A) and the compound (C) in a molten state or a solution state at 50 ° C. or higher, preferably 70 ° C. or higher, more preferably 120 ° C. or higher. . As the step of reacting in the molten state, it can be produced using a single-screw or twin-screw type screw kneader or an ordinary thermoplastic resin mixer represented by a kneader type heater. Moreover, as a process made to react in a solution state, it can also be made to react by adding a compound (C) simultaneously with melt | dissolving a polyester resin, or adding a compound (C) after melt | dissolving. Solvents in which the polyester is soluble include alcohols such as methanol, ethanol, and isopropyl alcohol, hydrocarbons such as toluene, xylene, cyclohexane, Solvesso 100, Solvesso 150, esters such as ethyl acetate and butyl acetate, acetone, methyl ethyl ketone, Examples thereof include ketones such as methyl isobutyl ketone and cyclohexanone, ether solvents such as tetrahydrofuran and butyl cellosolve, and chlorine solvents such as chloroform.

  In addition, after the adhesive composition is formed into a sheet shape, or after being applied to an adherend and after the adhesion is completed, the reaction can be advanced by heat treatment at 50 ° C. or higher as a post-process.

  The polyester resin used in the present invention is used as a composition containing an antioxidant in order to suppress thermal deterioration of the polyester resin during processing (to prevent occurrence of coloring of the resin due to thermal deterioration). desirable. As the antioxidant, for example, a phenol-based antioxidant, an organic phosphite-based compound and the like are suitable.

  Specific examples of the phenolic antioxidant used in the present invention include 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, and 2,6-di-tert. -Butyl 4-ethylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,4,6-tri-tert-butylphenol, 2-tert-butyl-4-methoxyphenol, 3-methyl-4-isopropyl Phenol, 2,6-di-tert-butyl-4-hydroxymethylphenol, 2,2-bis (4-hydroxydiphenyl) propane, bis (5-tert-butyl-4-hydroxy-2-methylphenyl) sulfide, 2,5-di-tert-amylhydroquinone, 2,5-di-tert-butylhydroquinone, 1,1- (3-tert-butyl-4-hydroxy-5-methylphenyl) butane, bis (3-tert-butyl-2-hydroxy-5-methylphenyl) methane, 2,6-bis (2-hydroxy-3- tert-butyl-5-methylbenzyl) -4-methylphenol, bis (3-tert-butyl-4-hydroxy-5-methylbenzyl) sulfide, bis (3-tert-butyl-5-ethyl-2-hydroxydiphenyl) Methane, bis (3,5-di-tert-butyl 4-hydroxydiphenyl) methane, bis (3-tert-butyl-2-hydroxy-5-methylphenyl) sulfide, 1,1-bis (4-hydroxyphenyl) Cyclohexane, ethylenebis [3,3-bis (3-tert-butyl-4-hydroxyphenyl) butyrate Bis [2- (2-hydroxy-3-tert-butyl5-methylbenzyl) -4-methyl-6-tert-butylphenyl] terephthalate, 1,1-bis (2-hydroxy-3,5-dimethylphenyl) ) -2-Methylpropane, 4-methoxyphenol, cyclohexylphenol, p-phenylphenol, catechol, hydroquinone, 4-tert-butylpyrocatechol, ethyl gallate, propyl gallate, octyl gallate, lauryl gallate, cetyl gallate, β-naphthol 2,4,5-trihydroxybutyrophenone, tris (3,5-di-tert-butyl-4-hydroxyphenyl) isocyanate, 1,3,5-trimethyl-2,4,6-tris (3,5- Di-tert-butyl-4-hydroxydibenzyl) , 1,6-bis [2- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] hexane, tetrakis [3- (3,5-di-tert-butyl-4-hydroxydiphenyl) ) Propionyloxymethyl] methane, bis (3-cyclohexyl-2-hydroxy-5-methylphenyl) methane, bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxyethyl] sulfide, n-otatadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, bis [3- (3,5-di-tert-butyl 4-hydroxydiphenyl) propionylamino] hexane, 2, 6-bis (3-tert-butyl-2-hydroxy-5-methylphenyl) -4-methyl Enol, bis [S- (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)] thioterephthalate, tris [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy Ethyl] isocyanurate, tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,1,3-tris (3-tert-butyl-4-hydroxy-6-methylphenyl) butane, etc. Is mentioned. These compounds may be used alone or in combination of two or more.

  The blending amount of the phenolic antioxidant is preferably 1.0 part by weight or less, particularly preferably 0.8 part by weight or less, while the preferred lower limit is 0.00 part by weight based on 100 parts by weight of the crystalline polyester resin (A). 01 parts by weight or more, particularly preferably 0.02 parts by weight or more. If the blending amount is less than 0.01 parts by weight, it is difficult to obtain the effect of suppressing heat deterioration during processing, and if it exceeds 1.0 part by weight, the effect of suppressing heat deterioration is saturated and not economical.

  Specific examples of the organic phosphite compound used in the present invention include, for example, triphenyl phosphite, tris (methylphenyl) phosphite, triisooctyl phosphite, tridecyl phosphite, tris (2-ethylhexyl). Phosphite, Tris (nonylphenyl) phosphite, Tris (octylphenyl) phosphite, Tris [decylpoly (oxyethylene) phosphite, Tris (cyclohexylphenyl) phosphite, Tricyclohexylphosphite, Tri (decyl) thiophosphite , Triisodecyl thiophosphite, phenyl bis (2-ethylhexyl) phosphite, phenyl diisodecyl phosphite, tetradecyl poly (oxyethylene) bis (ethylphenyl) phosphato, phenyl Dicyclohexyl phosphite, phenyl diisooctyl phosphite, phenyl di (tridecyl) phosphite, diphenyl cyclohexyl phosphite, diphenyl isooctyl phosphite, diphenyl 2-ethylhexyl phosphite, diphenyl isodecyl phosphite, diphenyl・ Cyclohexylphenyl phosphite, diphenyl (tridecyl) thiophosphite, nonylphenyl ditridecyl phosphite, phenyl p-tert-butylphenyl dodecyl phosphite, diisopropyl phosphite, bis [otadecyl poly (oxyethylene)] phosphite , Octyl poly (oxypropylene) tridecyl poly (oxypropylene) phosphite, monoisopropyl phosphite, diisode Ruphosphite, diisooctyl phosphite, monoisooctyl phosphite, didodecyl phosphite, monododecyl phosphite, dicyclohexyl phosphite, monocyclohexyl phosphite, monododecyl poly (oxyethylene) phosphite, bis (cyclohexylphenyl) phosphite Monocyclohexyl phenyl phosphite, bis (p-tert-butylphenyl) phosphite, tetratridecyl 4,4′-isopropylidene diphenyl diphosphite, tetratridecyl 4,4′-butylidene bis (2-tert -Butyl-5-methylphenyl) diphosphite, tetraisooctyl-4,4′-thiobis (2-tert-butyl-5-methylphenyl) diphosphite, tetrakis (nonylphenyl) Poly (propyleneoxy) isopropyl diphosphite, tetratridecyl propyleneoxypropyl diphosphite, tetratridecyl 4,4'-isopropylidene dicyclohexyl diphosphite, pentakis (nonylphenyl) bis [poly (propylene Oxy) isopropyl] triphosphite, heptakis (nonylphenyl) tetrakis [poly (propyleneoxy) isopropyl] pentaphosphite, heptakis (nonylphenyl) tetrakis (4,4′-isopropylidenediphenyl) pentaphosphite, decachys (nonyl) Phenyl) ・ heptakis (propyleneoxyisopropyl) octaphosphite, decaphenyl heptakis (propyleneoxyisopropyl) octaphosphite, bis (butoxycal) Ethyl) · 2,2-dimethylene-trimethylenedithiophosphite, bis (isooctoxycarbomethyl) · 2,2-dimethylenetrimethylenedithiophosphite, tetradodecyl · ethylenedithiophosphite, tetradodecyl · hexamethylenedithio Phosphite, tetradodecyl 2,2'-oxydiethylenedithiophosphite, pentadodecyl di (hexamethylene) trithiophosphite, diphenyl phosphite, 4,4'-isopropylidene-dicyclohexyl phosphite, 4,4'- Isopropylidene diphenyl alkyl (C12-C15) phosphite, 2-tert-butyl-4- [1- (3-tert-butyl-4-hydroxydiphenyl) isopropyl] phenyldi (p-nonylphenyl) phosphite, di Ridecyl 4,4'-butylidenebis (3-methyl-6-tert-butylphenyl) phosphite, dioctadecyl 2,2-dimethylene trimethylene diphosphite, tris (cyclohexylphenyl) phosphite, hexatridecyl 4,4 ′, 4 ″ -1,1,3-butanetriyl-tris (2-tert-butyl-5-methylphenyl) triphosphite, tridodecylthiophosphite, decaphenyl heptakis (propyleneoxyisopropyl) octabosphite Dibutyl pentakis (2,2-dimethylenetrimethylene) diphosphite, dioctylpentakis (2,2-dimethylenetrimethylene) diphosphite, didecyl-2,2-dimethylenetrimethylenediphosphite and their lithium and sodium , Potassium, magnesium, caldium, barium, zinc and aluminum metal salts. These compounds may be used alone or in combination of two or more.

  The compounding amount of the organic phosphite ester compound is preferably 3.0 parts by weight or less, particularly preferably 2.0 parts by weight or less, and preferably 0.01 parts by weight or less with respect to 100 parts by weight of the polyester resin. Above, especially preferably 0.02 parts by weight or more. If the blending amount is less than 0.01 parts by weight, it is difficult to obtain the effect of suppressing thermal deterioration during processing, and if it exceeds 3.0 parts by weight, the effect of suppressing thermal deterioration is saturated and not economical.

  Note that it is preferable to use a phenolic antioxidant and an organic phosphite ester compound in combination because the effect of suppressing thermal deterioration is further improved.

  In order to improve the melt strength of the resin and improve the moldability, the polyester resin composition used in the present invention may further contain an ultra high molecular weight acrylic polymer or a fluorine polymer in addition to the compound (C). It is also possible to add a copolymerized acrylic polymer. In particular, a polymer in the form of surrounding an ultra-high molecular weight fluorine polymer with an acrylic polymer (“Maybrene A-3000” manufactured by Mitsubishi Rayon Co., Ltd. as a product example) is oriented in the flow direction in the shear flow during extrusion. In addition, since the orientation is relaxed after discharge, the force to shrink the entire resin acts to develop the melt strength, and in addition, the melt strength can be easily improved with a very small addition amount, which is suitable for extrusion applications. is there. The addition amount is preferably 0.01 part or more and 1 part or less with respect to 100 parts of the polyester resin. More preferably, it is 0.02 part or more and 0.5 part or less.

  Other components can be appropriately added to the polyester resin composition of the present invention depending on the application. For example, impact resistance improvers, fillers, UV absorbers, surface treatment agents, pigment dispersants, lubricants, light stabilizers, pigments, antistatic agents, antibacterial agents, crosslinking agents, sulfur-based antioxidants, flame retardants, Examples include plasticizers, processing aids, foaming agents and the like.

  The sheet-like or film-like conductive resin molded article of the present invention is obtained by, for example, crystalline polyester resin (A), conductive fine powder (B), and other raw materials as required, a single screw extruder, a twin screw extruder, a kneader. It is produced by melting and kneading by a known method such as a two-roll method and pelletizing it by a method such as T-die, injection molding, or profile extrusion.

  A planar heating element in which at least one of a metal foil, a metal wire, and a conductive paste is connected as an electrode material to both ends of the molded product molded in this manner can be obtained.

  Examples are given below to illustrate the present invention in more detail. The measurement values described in the synthesis examples, examples, and comparative examples are measured by the following methods.

1. Average molecular weight: Calculated from the results of GPC measurement using a gel filtration permeation chromatography (GPC) 150c manufactured by Waters with chloroform as the eluent at a column temperature of 50 ° C. and a flow rate of 1 ml / min. Measurements of average molecular weight and weight average molecular weight were obtained. However, Showa Denko Co., Ltd. shodex KF-802, 804, 806 was used for the column.

2. Resin composition: The composition of the polyester resin was determined from its integral ratio by performing ¹ H-NMR analysis in a deuterated chloroform solvent using a nuclear magnetic resonance analyzer (NMR) Gemini-200 manufactured by Varian.

3. Glass transition temperature, melting point: Polyester resin 5 mg was put in an aluminum sample pan and sealed, and the temperature rising rate was 20 ° C./min using a differential scanning calorimeter (DSC) DSC-220 manufactured by Seiko Instruments Inc. It was obtained by measuring.

4). Acid value: Obtained by dissolving 0.2 g of a polyester resin in 20 ml of chloroform and titrating with a 0.1N potassium hydroxide ethanol solution. Phenolphthalein was used as the indicator.

5. Fabrication of a planar heating element: a conductive resin sheet formed with a T-die in a sheet shape having a thickness of 2 mm is cut into a rectangle having a width of 10 cm and a length of 11 cm, and a conductive silver paste (DP) along the edges of opposing short sides. -120H-1, Toyobo Co., Ltd.) was screen-printed so as to have a line width of 5 mm × length of 10 cm and a thickness of 20 μm in terms of dry film thickness, and pre-dried at 80 ° C. for 15 minutes. Subsequently, it put on the silver circuit which printed the tin plating copper foil of width 5mm as an electrode, and it adhere | attached using the tester industry company roll laminator. Lamination temperature was 170 ° C., pressure 0.3 mPa, speed 0.5 m / min. Further, the silver paste was cured at 130 ° C. for 30 minutes to obtain a planar heating element.

6). Sheet resistance: 5. The resistance between the bonded electrodes was measured with a digital multimeter using the planar heating element prepared in 1. Since the resistor between the electrodes is a square, the measured resistance value is a sheet resistance, and the unit is represented by Ω / □.

7). Peel strength: 5. The electrode of the planar heating element produced in the above was measured by peeling 180 ° at a pulling rate of 50 mm / min in an atmosphere of 25 ° C. using RTM100 manufactured by Toyo Baldwin.
(Judgment) ○: Adhesive strength of 2 N / cm or more
Δ: Adhesive strength of less than 2 N / cm, 0.5 N / cm or more
X: Adhesive strength less than 0.5 N / cm

8). Exothermic test: 5. A voltage was applied to the electrode of the sheet heating element produced in step 1 with a DC power source, and the voltage was adjusted so that a current of 100 mA flowed. The surface temperature after 30 minutes was measured with a thermocouple. The measurement was performed at room temperature of 25 ° C.

9. Blocking resistance: 5 sheets of conductive resin sheets and 6 PET films formed with a T-die in a 2 mm thick sheet were alternately stacked, left under an atmosphere of 80 ° C. for 24 hours under a load of 90 g / cm 2. . Thereafter, the conductive resin molded product was taken out, and in order to observe non-tackiness, the adhesive strength between the stacked sheets was measured at 25 ° C., and the following determination was performed.
(Judgment) A: 0 to 3 g / cm O: 3 to 5 g / cm
Δ: 5 to 15 g / cm ×: 15 g / cm or more

10. Flexibility: A conductive resin sheet molded with a T-die in a sheet shape having a thickness of 2 mm was applied with a metal rod having a diameter of 5 mm, bent at 25 ° C. for 5 times, and the occurrence of cracks was observed.
(Judgment) ○: No crack △: Slightly cracked ×: Significantly cracked

11. Moisture resistance: A conductive resin sheet molded with a T-die in a sheet shape having a thickness of 2 mm was allowed to stand for 240 hours under conditions of a relative humidity of 85% RH and 80 ° C., and then evaluated for blocking resistance and flexibility.
<Synthesis example of polyester resin (a)>
In a reaction vessel equipped with a stirrer, a thermometer and an outflow condenser, 199 parts of terephthalic acid, 162 parts of sebacic acid, 360 parts of 1,4-butanediol and 0.14 parts of tetrabutyl titanate were added, and the temperature was 180 to 240 ° C. The esterification reaction was performed for 1 hour. After completion of the esterification reaction, the reaction system was heated from 240 ° C. to 250 ° C., while the pressure inside the system was gradually reduced to 500 Pa over 60 minutes. Further, a polycondensation reaction was performed at 130 Pa or less for 65 minutes to obtain a polyester resin (a).

As a result of NMR analysis, the polyester resin (a) has a composition of terephthalic acid 60 mol%, sebacic acid 40 mol%, 1,4-butanediol 100 mol%, number average molecular weight 30000, acid value 38 eq / 10 ^6. g, a crystalline polyester having a glass transition temperature of -35 ° C and a melting point of 131 ° C. The results are shown in Table 1.

<Synthesis example of polyester resins (b) to (d)>
Polyester resins (b) to (d) were synthesized in the same manner as the polyester resin (a). Both are crystalline polyester resins having a melting point. The results are shown in Table 1.

<Synthesis example of comparative polyester resins (e) to (g)>
Comparative polyester resins (e) to (g) were synthesized in the same manner as the polyester resin (a). The results are shown in Table 2. The comparative polyester resin (e) has a low number average molecular weight and is outside the scope of the present invention. Comparative Synthesis Examples 2 and 3 have unclear melting points and are amorphous resins, which are outside the scope of the present invention.

<Example 1>
As a compound having a structure of -N = C = N-, 92 parts of crystalline polyester resin (a), 8 parts of raben 1255 (made by Colombian Carbon Japan Co., Ltd.) as conductive carbon black, 0.5 parts of P (manufactured by Rhein Chemie) and 0.3 parts by weight of bis [S- (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)] thioterephthalate as a stabilizer were mixed. The mixture was kneaded with an extruder (L / D = 30, screw diameter = 20 mm, full flight, compression ratio 2.0) set at a rotation speed of 30 rpm and a total barrel temperature of 180 ° C.
Next, the kneaded resin composition was extruded to a thickness of 2 mm through a T die at 170 ° C. using a single screw extruder (L / D = 25, full flight screw, screw diameter 65 mm), and conductive. A resin sheet was obtained. Extrusion suitability of the T die was very good without causing a neck-in (a phenomenon in which the width of the molded sheet narrows compared to the width of the T die). When this resin sheet was bent by hand, it had good flexibility and strength. Moreover, when the moisture resistance was evaluated, it was very good, and physical properties such as blocking resistance and flexibility after the moisture resistance test were not observed.

  The electrode was adhered to this resin sheet by the method described above, and the sheet resistance was measured and found to be 320Ω / □. When the exothermic test was conducted, a surface temperature of 45 ° C. was obtained. Further, the peel strength of the electrode had good adhesiveness of 2 N / cm or more. The results are shown in Table 3.

<Examples 2 to 4>
A planar heating element was prepared and evaluated in the same manner as in Example 1. Example 2 is an example in which conductive carbon black and graphite fine powder are used in combination. Similar to Example 1, good results were obtained with respect to moisture resistance, T-die extrusion property, and the like. Table 3 shows the formulation and results.

<Comparative Examples 1-3>
Evaluation was performed using a comparative resin in the same manner as in Example 1. In Comparative Example 1, the number average molecular weight of the polyester resin was low, but the viscosity was too low, resulting in dripping and poor T-die moldability. Moreover, when the obtained electroconductive sheet was bent, a crack entered and the blocking resistance was insufficient.

  Comparative Example 2 is an example using an amorphous high Tg polyester resin, but the T-die moldability was relatively good, but the obtained resin sheet despite having a sufficiently high number average molecular weight. Was brittle and could not be used.

  Comparative Example 3 is an example using an amorphous low Tg polyester resin, but the T-die moldability was relatively good, but the strength of the sheet was weak because it was amorphous and low Tg. Also, it could not withstand the use due to blocking.

<Comparative example 4>
In Comparative Example 4, polyethylene was used instead of the polyester resin, but the flexibility was good, but the adhesive strength of the electrode was very weak and could not be used. Further, the T-die extrusion property was not satisfactory because a slight neck-in was observed.

<Comparative Examples 5 and 6>
In Comparative Examples 5 and 6, although the polyester resin of the synthesis example is used, the compound (C) having a structure of -N = C = N- is not blended, but the physical properties decrease remarkably in moisture resistance. The flexibility after the test was poor and the blocking resistance was also poor. Furthermore, neck-in occurred in the T-die moldability.

Table 4 shows the formulation and results of Comparative Examples 1-6.

In addition, the stabilizers described in Tables 3 and 4 mean the following compounds.
X: Bis [S- (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)] thioterephthalate The numerical values in the amounts of polyester, reactive compounds, stabilizers and additives in the table are weights. Part.

  As described above, the conductive resin molded article of the present invention has both excellent moldability and flexibility, and further provides an on-surface heating element with good moisture resistance.

Claims (7)

  A crystalline polyester resin (A) having a number average molecular weight of 5,000 to 50,000 and a melting point of 50 ° C. or higher, a conductive fine powder (B), and a compound (C) having a structure of —N═C═N— are included. The conductive resin composition characterized by the above-mentioned.   The conductive resin composition according to claim 1, wherein the crystalline polyester (A) has a glass transition temperature of 40 ° C. or lower.   The conductive resin composition according to claim 1 or 2, wherein the compound (C) is a polycarbodiimide containing at least two structures of -N = C = N- in one molecule.   The conductive resin composition according to claim 1, wherein at least one of the molecular terminals of the compound (C) is an isocyanate group.   The conductive resin composition according to claim 1, wherein the conductive fine powder (B) is carbon black and / or graphite fine powder.   A sheet-like or film-like molded article comprising the conductive resin composition according to any one of claims 1 to 5.   A planar heating element in which at least one of a metal foil, a metal wire, and a conductive paste is connected as an electrode material to both ends of the molded product according to claim 6.