JP2007224207A - Electroconductive composition, electroconductive coating material, electroconductive fiber material, method for producing electroconductive fiber material, and flat heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroconductive composition capable of providing a flat heater having a small rate of change of electrical resistance caused by the increase of temperature, an electroconductive coating material, an electroconductive fiber material exhibiting proper electric resistance and electroconductivity, and having the electroconductive composition, a method for producing the electroconductive fiber material, and the flat heater having proper heat build-up without excess and deficiency even if a high voltage is applied. <P>SOLUTION: The electroconductive composition comprises a polyurethane, a carbon black mixture comprising carbon black having 100-250 ml/100 g dibutyl phthalate oil absorption and carbon black having >250 ml/100 g dibutyl phthalate oil absorption, and talc having 1-20 μm average primary particle diameter. The electroconductive coating material contains a solvent besides them. The electroconductive fiber material is obtained by covering a fiber material with the electroconductive composition. The flat heater has the electroconductive fiber material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductive composition, a conductive paint, a conductive fiber material, a method for manufacturing a conductive fiber material, and a planar heating element.

  Conventionally, a conductive fiber material is generally manufactured by applying a conductive paint using a fiber material such as synthetic fiber or natural fiber as a base material and imparting conductivity to the fiber material.

  Examples of the conductive coating applied to the fiber material include resins (binder resin components) such as urethane resin, cellulose resin, aminoalkyd resin, and aminoacrylic resin, and metal powder such as stainless steel, tin, copper, and aluminum; A material in which a metal oxide such as zinc oxide; a conductive material such as titanium dioxide coating mica, silicon, cobalt sulfide, or the like is mixed and dispersed is known.

  However, when the metal powder is used in a conductive heating element such as a conductive fiber material, there is a problem that the electric resistance value becomes excessively low. Further, since the metal powder has a large specific gravity, the metal powder is easily separated from the binder resin component during storage of the conductive coating material, easily settles on the bottom of a storage container or the like, and easily aggregates. Furthermore, when the conductive paint is stored for a long period of time, the metal powder solidifies and it becomes difficult to re-disperse to the original state even if stirring is performed. As a result, there is a drawback that the conductivity of the coating film obtained by applying the conductive paint is difficult to be uniform.

  Further, when a metal oxide is used as the conductive material, there is a problem that the electric resistance value of the formed coating film becomes excessively high, and the conductivity is insufficient when used for a conductive heating element or the like.

  On the other hand, it is known that carbonaceous conductive materials such as conductive carbon black and scale-like graphite carbon can also impart conductivity. For example, it has been proposed that a conductive paint obtained by blending a specific ratio of conductive carbon black and scaly graphite carbon is excellent in storage stability and can form a coating film excellent in conductivity (Patent Document 1). . However, when a conductive paint as reported therein is applied to a conductive heating element made of conductive fiber material, the additional voltage to the heating element is limited (the electric resistance value does not increase). There's a problem.

  Therefore, the present applicant uses graphite carbon and carbon black having a dibutyl phthalate oil absorption of less than 100 ml / 100 g as a conductive substance, and disperses it in an organic solvent together with polyurethane (polyurethane dissolves), thereby achieving an appropriate electrical property. It has been found that a conductive paint having a resistance value and conductivity can be obtained (Patent Document 2). However, when the conductive fiber material using the conductive paint is used for a planar heating element or the like, if the temperature rises (heats) to some extent after turning on the power, the conductive fiber material or the heating element Further, there is a problem that the electrical resistance value of the sheet heating element or the like included in is greatly changed from the electrical resistance value before the power is turned on, and further improvement is required.

JP2001-064565 WO2005 / 012428

  The present invention can provide a sheet heating element having a low rate of change in electric resistance value due to temperature rise, a conductive composition, a conductive paint, and an appropriate electric resistance value comprising the conductive composition. An object of the present invention is to provide a conductive fiber material having conductivity and a method for manufacturing the same. Another object of the present invention is to provide a planar heating element having an appropriate exothermic property without excess or deficiency even when a high voltage of, for example, 200 volts is applied.

  In order to solve the above problems, the present inventors have made extensive studies on the types of binder resins, the characteristics of carbonaceous conductive materials and fillers, the composition ratios, and the like. As a result, specific dibutyl phthalates have been added to polyurethane. A conductive fiber material obtained by coating a fiber material with a conductive composition obtained by blending two types of carbon black mixture having an oil absorption amount and specific talc has an appropriate electrical resistance value and conductivity. In addition, when the conductive fiber material is used for a planar heating element or the like, the present inventors have found that the rate of change of the electrical resistance value of the planar heating element due to temperature rise is low, and completed the present invention.

That is, according to the present invention,
1. 100 parts by weight of polyurethane (A),
Carbon black mixture (B) comprising 65 to 95% by weight of carbon black (b1) having a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g and 35 to 5% by weight of carbon black (b2) having a dibutyl phthalate oil absorption of 250 ml / 100 g 30-60 parts by weight;
30-60 parts by weight of talc (C) having a primary average particle size of 1-20 μm,
A conductive composition (D) comprising:
2. Said 1 conductive composition (D),
500 to 1500 parts by weight of the solvent (E) as an amount with respect to 100 parts by weight of the polyurethane (A) in the conductive composition (D);
A conductive paint (F) comprising:
3. A conductive fiber material (G) obtained by coating the conductive composition (D) described in 1 above on a fiber material;
4). The method for producing a conductive fiber material (G), wherein the conductive paint (F) according to 2 is applied to a fiber material;
5). A sheet heating element (H) comprising the conductive fiber material (G) described in 3 above;
Is provided.

  Conductive fiber material (G) obtained by coating the fiber material (g) with the conductive composition (D) of the present invention comprising a specific proportion of polyurethane (A), carbon black mixture (B) and talc (C). ) Has an appropriate electrical resistance value and conductivity, and when the conductive fiber material (G) is used for the sheet heating element (H), the sheet heating element (H) is caused by temperature rise. The change rate of the electrical resistance value is low, and it can have moderate heat generation and thermal stability without excess or deficiency.

  Hereinafter, the conductive composition (D), the conductive paint (F), the conductive fiber material (G), the method for producing the conductive fiber material (G), and the planar heating element (H) according to the present invention will be described in detail. To do.

  The conductive composition (D) of the present invention comprises 100 parts by weight of polyurethane (A), 65 to 95% by weight of carbon black (b1) having a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g, and a dibutyl phthalate oil absorption of 250 ml / 30 to 60 parts by weight of a carbon black mixture (B) composed of 35 to 5% by weight of carbon black (b2) exceeding 100 g, and 30 to 60 parts by weight of talc (C) having a primary average particle diameter of 1 to 20 μm. Become.

  The polyurethane (A) is not particularly limited, but a thermoplastic polyurethane elastomer is preferable. Thermoplastic polyurethane elastomers include polyester-based, polyether-based, polycarbonate-based, and the like, and those prepared commercially or by a known method can be used alone or in combination of two or more.

  In the present invention, carbon black (b1) having a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g with respect to 100 parts by weight of the conductive composition (D) is assumed to impart conductivity to the conductive composition (D). 30) to 60 parts by weight of a carbon black mixture (B) comprising 35 to 5% by weight of carbon black (b2) having an oil absorption of 65 to 95% by weight and a dibutyl phthalate oil absorption of 250 ml / 100 g.

  Specific examples (product examples) of carbon black (b1) having a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g include, for example, # 3050B, # 3350B (above, manufactured by Mitsubishi Chemical Corporation), Seast 116HM, Seast FM, Seast FY (above, manufactured by Tokai Carbon Co., Ltd.), Denka Black (manufactured by Electrochemical Industry Co., Ltd.) and the like can be mentioned. These may be used alone or in combination of two or more. A preferred range of the oil absorption of dibutyl phthalate in carbon black (b1) is 150 to 200 ml / 100 g.

  Specific examples (product examples) of carbon black (b2) having a dibutyl phthalate oil absorption exceeding 250 ml / 100 g include, for example, Ketjen Black EC (manufactured by Lion Corporation), Ensaco 350G (manufactured by Ribason Corporation), etc. Can be mentioned. These may be used alone or in combination of two or more. A preferable range of the oil absorption of dibutyl phthalate in carbon black (b2) is 300 ml / 100 g or more.

  The content of carbon black (b1) having a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g in the carbon black mixture (B) is 65 to 95% by weight, preferably 70 to 90% by weight. On the other hand, the carbon black (b2) content of the dibutyl phthalate oil absorption in the carbon black mixture (B) exceeding 250 ml / 100 g is 35 to 5% by weight, preferably 30 to 10% by weight. By using carbon black (b1) and carbon black (b2) whose dibutyl phthalate oil absorption is in the above range in an amount within the above range, the conductive fiber material (G) is used as the planar heating element (H). If used, the rate of change in the electrical resistance value of the sheet heating element (H) due to temperature rise is low, overcurrent flows when energized under a constant voltage, or conductive heating elements such as the conductive fiber material (G) are excessive. Heat generation can be prevented.

  The usage-amount of a carbon black mixture (B) is 30-60 weight part normally with respect to 100 weight part of said polyurethanes (A), Preferably it is 35-55 weight part. When the amount of the carbon black mixture (B) used is less than 30 parts by weight, the electrical resistance value of the conductive fiber material (G), that is, the conductive composition (D) becomes too high, and it becomes conductive under a constant voltage. In addition to being inferior, the amount of heat generated tends to be small when used as a conductive heating element such as a conductive fiber material (G). On the other hand, when the amount of use exceeds 60 parts by weight, the electrical resistance value of the conductive fiber material (G), that is, the conductive composition (D) becomes too low, and the conductive fiber material (G having a predetermined resistance value) ) Is not obtained.

  The particle diameters of the carbon black (b1), carbon black (b2), and carbon black mixture (B) described above are not particularly limited, but those having a primary average particle diameter in the range of 10 to 80 nm are preferably used. By setting it as this range, it is excellent in the handleability of a conductive paint (F).

  Talc (C) constituting the conductive composition (D) of the present invention is in the form of powder and has a primary average particle size of 1 to 20 μm. When the primary average particle diameter is smaller than 1 μm, the resistance value change rate of the conductive composition (D) due to the change with time of the conductive paint (F) (hereinafter, sometimes referred to as “paint resistance value change rate”). Becomes higher. On the other hand, when the primary average particle diameter is larger than 20 μm, the resistance value change rate (paint resistance value change rate) of the conductive composition (D) due to the change with time of the conductive paint (F) becomes high. It will be inferior to the adhesiveness of a fiber material (g) and an electroconductive composition (D). The primary average particle diameter of talc (C) is preferably 2 to 15 μm, more preferably 3 to 10 μm.

  Preferable specific examples (product names) of talc (C) having a primary average particle size of 1 to 20 μm include, for example, Microace, SG-series (manufactured by Nihon Talc Co., Ltd.), Hytron, Microlite, High A rack (made by Takehara Chemical Co., Ltd.) etc. can be mentioned.

  The amount of talc (C) having a primary average particle size of 1 to 20 μm is usually 30 to 60 parts by weight, preferably 45 to 55 parts by weight, based on 100 parts by weight of the polyurethane (A). When the amount of talc (C) having a primary average particle size of 1 to 20 μm is less than 30 parts by weight, the surface shape due to temperature rise when the conductive fiber material (G) is used for the surface heating element (H). The rate of change of the electrical resistance value of the heating element (H) is increased, and the surface of the conductive composition (D) is inferior in smoothness (dynamic friction coefficient is increased). There is a concern that the conductive fiber material (G) is cut. On the other hand, when it exceeds 60 parts by weight, the resistance value change rate (paint resistance value change rate) of the conductive composition (D) due to the change over time of the conductive paint (F) becomes high, and further the fiber material (g). It will be inferior to the adhesiveness of a conductive composition (D).

  The conductive paint (F) of the present invention comprises 500 to 1500 parts by weight of solvent (100 to 100 parts by weight of the polyurethane (A) in the conductive composition (D) and the conductive composition (D). E).

  The conductive composition (D) used for the conductive paint (F) of the present invention is as described above.

  The solvent (E) used in the conductive paint (F) of the present invention is not particularly limited as long as it can dissolve or disperse the polyurethane (A). Preferred examples include the following polar organic solvents. . That is, cyclic ether compounds such as tetrahydrofuran (hereinafter sometimes abbreviated as THF), furan, tetrahydropyran, pyran, dioxane, 1,3-dioxolane, trioxane; N, N-dimethylformamide, N, N-dimethyl Dialkyl ketamide compounds such as acetamide; dialkyl sulfoxide compounds such as dimethyl sulfoxide and diethyl sulfoxide; ketone compounds such as acetone, methyl ethyl ketone (hereinafter abbreviated as MEK) and diethyl ketone; ethanol, 2-propanol, Examples thereof include alcohol compounds such as 1-butanol; chlorinated hydrocarbon compounds such as dichloroethylene, dichloroethane, and dichlorobenzene. Of these, cyclic ether compounds and ketone compounds are more preferable, tetrahydrofuran, 1,3-dioxolane, and methyl ethyl ketone are more preferable, and tetrahydrofuran is particularly preferable. These can be used alone or in combination of two or more.

  The amount of the solvent (E) used is usually 500 to 1500 parts by weight, preferably 700 to 1300 parts by weight, and more preferably 800 to 1200 parts by weight with respect to 100 parts by weight of the polyurethane (A). When the amount of the solvent is less than 500 parts by weight, the viscosity of the conductive paint (F) becomes too high and handling becomes difficult. On the other hand, when it exceeds 1500 parts by weight, the viscosity of the conductive paint (F) becomes too low. It becomes difficult to cover the conductive composition (D) on the fiber material (g) which is the base material.

  Other conductive fillers other than the carbon black [(b1), (b2)] described above can be blended in the conductive paint (F) to such an extent that the effects of the present invention are not impaired (the talc described above is conductive). Not a filler.) Other conductive fillers are not particularly limited as long as they are usually used for such applications, but are roughly classified into inorganic conductive fillers and organic conductive fillers, and the following may be mentioned.

  Examples of inorganic conductive fillers include metal powders such as iron, cobalt, nickel, and aluminum; metal oxides such as titanium oxide, zinc oxide, iron oxide, and tungsten oxide; and the above scaly graphite such as carbon fiber, fullerene, and carbon nanotube. And carbonaceous fillers other than carbon and the carbon black. Examples of the organic conductive filler include conductive polymers such as polyaniline and polypyrrole; organometallic complexes represented by iron phthalocyanine, ferrocene, and the like.

  If desired, the conductive paint (F) of the present invention includes a plasticizer, a dispersant, a coating surface conditioner, a flow conditioner, an ultraviolet absorber, an ultraviolet stabilizer, an antioxidant, a crosslinking reaction accelerator, and a crosslinking reaction inhibitor. Various known additives such as an agent can be blended to such an extent that the effects of the present invention are not impaired.

  The conductive fiber material (G) of the present invention is obtained by coating the conductive composition (D) on a fiber material (g). Here, “coating” means not only covering the outer surface of the fiber material but also penetrating into the inside of the fiber material (g), and particularly in the case of a yarn formed by twisting single fibers. It also means that the conductive composition (D) is impregnated in the yarn, and the single fibers constituting the yarn are covered and / or permeated one by one.

  The shape, material, form and the like of the fiber material (g) serving as the base material for the conductive fiber material (G) of the present invention are not particularly limited. For example, short fibers, long fibers, single fiber yarns, yarns that are short fibers or long fiber aggregates, fabrics that are aggregates of yarns, and the like can be used. The material of the fiber material (g) may be a synthetic fiber or a natural fiber. Among these, it is preferable to use a thread made of polyester, nylon or cotton. As the polyester, an arbitrary polyester such as an alkyl polyester or an aryl polyester can be selected and used. As nylon, arbitrary things, such as nylon-6 and nylon-6,6, can be used. Although the form of the yarn as the fiber material (g) is not particularly limited, it is preferably in the range of 500 to 1500 decitex by twisting a plurality of yarns.

In the conductive composition (D) and the conductive fiber material (G) formed by coating the conductive composition (D) on the fiber material (g), the electrical resistance value per unit length is as follows. Is preferably in the range of 3000 to 9000 Ω / cm. For this purpose, the electrical resistance value of the conductive composition (D) covering the fiber material (g) (base material) is preferably in the range of 1.0 to 3.0 Ω · cm.
When the electrical resistance value per unit length of the conductive fiber material (G) is within the above range, it is possible to energize at an appropriate voltage, and no excessive heat is generated due to overcurrent. Therefore, the calorific value is within the appropriate range.

  The method of coating the conductive composition (D) on the fiber material (g) is not particularly limited, and the conductive paint (F) obtained by dissolving or dispersing the conductive composition (D) in the solvent (E) is used as the fiber. Method of applying to material (g); Method of melting conductive composition (D) by heat and applying to fiber material (g); First forming conductive composition (D) into a sheet, And a method of performing a heat treatment after being wound around (g). Among these coating methods, the method according to the method for producing the conductive fiber material (G) of the present invention described below is preferable.

  That is, the method for producing a conductive fiber material (G) of the present invention is characterized in that the conductive paint (F) is applied to the fiber material (g). The method for applying the conductive paint (F) to the fiber material (g) is not particularly limited, and it can be applied by a conventional coating method. More specifically, the conductive paint (F) can be applied and impregnated on the fiber material by means of dip coating, air spray coating, airless spray coating, various electrostatic coatings, roll coating, brush coating, and the like. . Among these, dip coating is preferably used.

  The conductive composition (D) contained in the conductive paint (F) used in the production method of the present invention is the same as described above.

  The planar heating element (H) of the present invention is characterized by having the above-described conductive fiber material (G) of the present invention. Such a planar heating element (H) is, for example, a conductive fiber material (G) having a thread-like shape as a conductive weft extending between two electrodes, and a non-conductive warp and woven fabric extending substantially parallel to the electrode. This is used as a heat generating layer, and an insulating layer made of an insulating sheet is laminated on the front and back surfaces of the heat generating layer and the electrode.

  Hereinafter, the planar heating element (H) of this invention is demonstrated based on drawing. FIG. 1 is a schematic perspective view of a planar heating element according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a principal part taken along line II-II shown in FIG.

  As shown in FIGS. 1 and 2, the planar heating element 2 according to the present invention has a planar heating layer 4 and insulating layers 6 laminated on both sides of the heating layer 4. Elongated electrodes 8 and 8 are formed on both sides of the heat generating layer 4 along the longitudinal direction.

  In the present embodiment, a woven fabric of conductive wefts extending between the electrodes 8 and 8 and non-conductive warps extending substantially parallel to the electrodes 8 and 8 is used as the heat generating layer 4. As the non-conductive warp, for example, a yarn obtained by immersing a polyester fiber in a resin solution and drying it is used.

  The electrodes 8 and 8 disposed on both sides of the heat generating layer 4 are not particularly limited, but in this embodiment, the electrodes 8 and 8 are configured by flexible metal wires knitted so as to be connected to the conductive wefts constituting the heat generating layer 4. . The thickness of the electrode 8 is about the same as that of the heat generating layer 4 and is about 0.8 to 1.4 mm.

  The insulating layers 6 and 6 are laminated on the front and back surfaces so as to cover all of the heat generating layer 4 and the electrodes 8 and 8. Both side ends 10, 10 of the insulating sheet are heat-sealed to each other. In this embodiment, the insulating layer 6 has a thickness of 0.2 to 0.5 mm, and is formed by a calendar method or the like.

  The planar heating element (H) of the present invention is not limited to the above-described embodiment, and can take various forms within the scope of the present invention.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. “Parts” and “%” in Examples and Comparative Examples are based on weight.

[Measuring Method 1] Dibutyl phthalate of carbon black (hereinafter sometimes abbreviated as “DBP”) oil absorption The DBP oil absorption of carbon black is a value measured by the following test method.
A dry sample of carbon black 1.00 ± 0.01 g is placed on a smooth glass plate. If it is granular, apply moderate pressure with a spatula to break the grain. Gently pour about 1/2 of the required DBP amount from the burette onto the glass plate, spread the DBP evenly in a circular shape, and then move the sample onto the DBP to disperse it little by little. Knead with drawing operations. The sample adhering to the spatula is removed with another spatula, and about 1/3 to 1/4 of DBP is further added, and the same operation is repeated to make the mixture uniform. When the end point is approached, add one drop at a time, and when the end point is nearer, add one-half drop, and the end point is the point where the whole becomes one tight block. This operation should be completed in 10-15 minutes. After 3 minutes from the end of the operation, the DBP dripping amount in the burette is read, and the oil absorption amount is calculated by the following equation.
OA = 100 × (V / W)
(OA: oil absorption (ml / 100 g), V: amount of DBP used until the end point (ml), W: weight of dry sample (g))

[Measurement Method 2] Electrical Resistance Value of Conductive Composition (D) The electrical resistance value of the conductive composition (D) is a value measured by the following test method.
(1) Preparation of test film A conductive paint is applied onto a 50 μm-thick polyethylene terephthalate film, and a film having a uniform thickness is formed using a baker-type applicator (manufactured by Rigaku Corporation). It is dried for 5 minutes on a 40 ° C. hot plate and then for 5 minutes on a 80 ° C. hot plate.
(2) Measurement of electrical resistance value of conductive composition (D) The test film prepared in (1) was cut into (5 cm ± 0.5 mm) × (6 cm ± 0.5 mm), and 5 mm at both ends on the short side was cut. Fasten with stainless steel clips each 5 cm wide. A tester is connected to the clips at both ends, and the surface electrical resistance value r (Ω) of the film (5 cm ± 0.5 mm) × (5 cm ± 0.5 mm) is measured. The thickness of the film is measured with a thickness meter, and the electrical resistance value ρ (Ω · cm) of the conductive composition (D) is calculated by the following formula.
ρ = r × (T × 5) / 5 = r × T
(Ρ: electric resistance value (Ω · cm) of conductive composition (D), T: film thickness (cm), r: surface electric resistance value (Ω))

[Measurement Method 3] Electrical Resistance Value per Unit Length of Conductive Fiber Material (G) The electrical resistance value per unit length of the conductive fiber material (G) is a value measured by the following test method.
The conductive fiber material (G) is stretched between the electrodes with an interval of (5 cm ± 0.5 mm) so as not to sag, and a constant voltage is applied between the electrodes.
The electrical resistance value R1 (Ω) of the conductive fiber material (G) stretched between the electrodes is read with a tester, and the electrical resistance value R per unit length of the conductive fiber material (G) is calculated by the following formula. (Ω / cm) is calculated.
R = R1 / L
(R: electrical resistance value per unit length of conductive fiber material (G) (Ω / cm), L: length of conductive fiber material (G) (cm))

[Measuring method 4] Rate of change of electrical resistance value of sheet heating element (H) due to temperature rise during energization (1) Preparation of sheet heating element sample for test Made of polyester with length 10cm, width 15cm, thickness 0.1cm Two electrodes having a width of 1 cm and a thickness of 0.1 cm, which are formed by weaving flexible copper electrode wires having a length of 15 cm, are arranged in parallel on a mesh-like base fabric with an interval of 10 cm. In the width direction, it is arranged so that both the left and right sides from the electrode to the edge of the base fabric are 1.5 cm, and in the length direction, the ends of the two electrode lines and the ends of the base fabric are aligned with one end The other end is arranged so that a 5 cm electrode protrudes from the base fabric. The base fabric portion is impregnated with the conductive paint produced in each Example and each Comparative Example, dried on a hot plate at 70 ° C. for 20 minutes, and then dried on a hot plate at 90 ° C. for 10 minutes. After drying, sandwiched between two vinyl chloride sheets (length 15 cm, width 20 cm, thickness 0.45 cm), the ends of the four sides of the two vinyl chloride sheets are hot-pressed and thermally fused, and then the electrodes Two electric wires for energization were connected to each of the two to produce a planar heating element sample for testing.
(2) Measurement of change rate of electrical resistance value of sheet heating element (H) due to temperature rise during energization The rate of change of electrical resistance value of sheet heating element (H) due to temperature rise during energization is as follows. It is the result of measurement.
The electrical resistance value R0 (23 ° C.) before energization of the test sheet heating element (H) is read with a tester. Next, electricity is applied so that the temperature of the test sheet heating element (H) is 80 ° C., and the electrical resistance value R1 of the test sheet heating element (H) at 80 ° C. is read with a tester.
The change rate x (%) of the electrical resistance value of the planar heating element (H) due to the temperature rise during energization is calculated by the following equation.
x = 100 × (R1-R0) / R0 (%)

[Measurement method 5] Smoothness of surface of conductive composition (D) (dynamic friction coefficient)
The dynamic friction coefficient of the film is used as an index indicating the smoothness of the surface of the conductive composition (D). The dynamic friction coefficient is calculated in accordance with JIS K 7125 using the test film prepared by the measurement method 2, and the surface is made smooth by the conductive composition (D).

In a polypropylene container, 100 parts by weight of polyester polyurethane P22SRNAT (manufactured by Nippon Polyurethane Co., Ltd.) was dissolved in 865 parts by weight of tetrahydrofuran (hereinafter sometimes abbreviated as “THF”). Thereafter, 30 parts by weight of Denka Black (manufactured by Denki Kagaku Kogyo Co., Ltd .: DBP oil absorption 180 ml / 100 g) as carbon black (b1) and Ketjen Black EC (Lion ( Co., Ltd .: DBP oil absorption: 360 ml / 100 g) and 10 parts by weight of L-1 (primary average particle size: 4.9 μm: manufactured by Nippon Talc Co., Ltd.) as talc, and pigment dispersion and 1000 parts by weight of zirconia beads were added for mixing, and the mixture was shaken for 2 hours with a pigment dispersing machine (manufactured by Toyo Seiki Seisakusho). Thereafter, the zirconia beads were removed by decantation to obtain a conductive paint (F) (1) having a solid concentration of 18.0%. (Hereinafter, in each example and each comparative example, the amount of the solvent (E) was adjusted so that the solid content concentration of the conductive paint (F) was approximately 18.0%.)
A polyester multifilament yarn (1100 dtex) is used as the fiber material (g) as a base yarn, and the conductive paint (F) (1) obtained by the above method is applied to the yarn, followed by drying. Then, a thread coated with 0.04 g of the conductive composition (D) (1) per 1 m of the base thread, that is, the conductive fiber material (G) (1) was produced.
In addition, a planar heating element (H) (1) was produced by the [Measuring method 4].

  It was 1.2 ohm * cm when the electrical resistance value of produced electroconductive composition (D) (1) was measured by the said [measurement method 2]. In addition, when the electrical resistance value per unit length of the produced conductive fiber material was measured by the above [Measuring method 3], it was 5570 Ω / cm. Further, the rate of change in the electrical resistance value of the sheet heating element (H) (1) due to the temperature rise during energization was measured by the above [Measuring method 4], and was 6.6%. Further, the surface smoothness (coefficient of dynamic friction) of the conductive composition (D) (1) was measured by [Measurement Method 5] and found to be 0.9. The results are shown in Table 1.

  The same operation as in Example 1 was performed except that 35 parts by weight of Denka Black was used as carbon black instead of 30 parts by weight, and 5 parts by weight of Ketjen Black EC was used instead of 10 parts by weight. F) (2), conductive composition (D) (2), conductive fiber material (G) (2) and planar heating element (H) (2) were obtained and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

  Other than using 40 parts by weight instead of 30 parts by weight of Denka black as carbon black, using 5 parts by weight of Ketjen Black EC instead of 10 parts by weight, and using 890 parts by weight of THF instead of 865 parts by weight. The same operation as in Example 1 was performed, and the conductive paint (F) (3), the conductive composition (D) (3), the conductive fiber material (G) (3), and the planar heating element (H) (3 And evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

  Conductive paint (F) (F) (except that 30 parts by weight of Denka black as carbon black was used, 35 parts by weight was used, and 890 parts by weight of THF was used instead of 865 parts by weight). 4), a conductive composition (D) (4), a conductive fiber material (G) (4), and a planar heating element (H) (4) were obtained and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 1]
Conductive paint (F) (5), conductive properties are the same as in Example 1, except that 40 parts by weight of Denka black is used instead of 30 parts by weight of carbon black and ketjen black EC is not used. Composition (D) (5), conductive fiber material (G) (5), and sheet heating element (H) (5) were obtained and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 2]
The same operation as in Example 1 was performed except that 39 parts by weight of Denka Black as carbon black was used instead of 30 parts by weight and 1 part by weight of Ketjen Black EC was used instead of 10 parts by weight. F) (6), conductive composition (D) (6), conductive fiber material (G) (6) and planar heating element (H) (6) were obtained and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 3]
The same operation as in Example 1 was carried out except that 25 parts by weight of Denka Black as carbon black was used instead of 30 parts by weight and 15 parts by weight of Ketjen Black EC was used instead of 10 parts by weight. F) (7), conductive composition (D) (7), conductive fiber material (G) (7) and planar heating element (H) (7) were obtained and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 4]
Instead of using 30 parts by weight of Denka Black as carbon black, 90 parts by weight was used, Ketjen Black EC was not used, and Talc L-1 was not used. F) (8), conductive composition (D) (8), conductive fiber material (G) (8) and planar heating element (H) (8) were obtained and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 5]
Without using Denka Black and Ketjen Black EC as carbon black, graphite carbon black # 45L (manufactured by Mitsubishi Chemical Corporation), which is carbon black having a dibutyl phthalate oil absorption of 45 ml / 100 g, is used, and graphite is used. The same as in Example 1 except that 90 parts by weight of J-CPB (manufactured by Nippon Graphite Industry Co., Ltd.) was used, talc L-1 was not used, and 910 parts by weight was used instead of 865 parts by weight of THF. To obtain a conductive paint (F) (9), a conductive composition (D) (9), a conductive fiber material (G) (9) and a sheet heating element (H) (9), Evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 6]
The same operation as in Example 1 was carried out except that talc L-1 was not used and 635 parts by weight of THF was used instead of 865 parts by weight, and the conductive paint (F) (10), conductive composition (D ) (10), conductive fiber material (G) (10) and planar heating element (H) (10) were obtained and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

From the results of Table 1, in Comparative Example 1 in which carbon black (b2) having a dibutyl phthalate oil absorption of more than 250 ml / 100 g was not used, the rate of change in the electrical resistance value of the planar heating element (H) due to the temperature rise during energization Has become too expensive.
Further, the proportion of carbon black (b1) having a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g in the carbon black mixture (B) is too high, and the proportion of carbon black (b2) having a dibutyl phthalate oil absorption of 250 ml / 100 g is too high. In Comparative Example 2, which is too low, the rate of change of the electrical resistance value of the planar heating element due to the temperature rise during energization is too high.
In addition, the proportion of carbon black (b1) having a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g in the carbon black mixture (B) is too low, and the proportion of carbon black (b2) having a dibutyl phthalate oil absorption of 250 ml / 100 g is too low. In Comparative Example 3, which is too high, the electrical resistance value of the conductive composition (D) is too low, and the electrical resistance value per unit length of the conductive fiber material (G) is too low, resulting in poor heat generation. It was.

Carbon black (b2) and talc (C) in which the amount of carbon black (b1) having a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g is too large and the amount of dibutyl phthalate oil absorption exceeds 250 ml / 100 g is used. In Comparative Example 4, the electrical resistance value of the conductive composition (D) was too low, and the electrical resistance value per unit length of the conductive fiber material (G) was too low, resulting in poor heat generation. .
Also, carbon black (b1) with a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g, carbon black (b2) with a dibutyl phthalate oil absorption of over 250 ml / 100 g, and talc (C) are not used, and the dibutyl phthalate oil absorption is 100 ml. In Comparative Example 5 using less than / 100 g of carbon black and graphite, the rate of change in the electrical resistance value of the planar heating element due to the temperature rise during energization was too high.
Moreover, in the comparative example 6 which is not using talc (C), the surface smoothness of the electroconductive composition (D) has deteriorated.

  On the other hand, in Examples 1-4 which are this invention, the electrical resistance value of a conductive composition (D) is moderately high, and the electrical resistance value per unit length of a conductive fiber material (G) is also moderate. In addition, the rate of change of the electrical resistance value of the planar heating element due to the temperature rise during energization is kept low.

  The conductive fiber material (G) obtained by coating the fiber composition (D) with the conductive composition (D) of the present invention is suitable for use in a conductive heating element for the planar heating element (H). Thus, the sheet heating element (H) of the present invention is useful for an electric hot futon, a soil heating element for raising seedlings, a road heating element for melting snow and melting ice, and the like.

FIG. 1 is a schematic perspective view of a planar heating element according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of an essential part taken along line II-II shown in FIG.

Explanation of symbols

2 ... Planar heating element 4 ... Heat generation layer 6 ... Insulating layer 8 ... Electrode 10 ... Side edge

Claims (5)

100 parts by weight of polyurethane (A),
Carbon black mixture (B) comprising 65 to 95% by weight of carbon black (b1) having a dibutyl phthalate oil absorption of 100 to 250 ml / 100 g and 35 to 5% by weight of carbon black (b2) having a dibutyl phthalate oil absorption of 250 ml / 100 g 30-60 parts by weight;
30-60 parts by weight of talc (C) having a primary average particle size of 1-20 μm,
A conductive composition (D) comprising: The conductive composition (D) according to claim 1,
500 to 1500 parts by weight of the solvent (E) as an amount with respect to 100 parts by weight of the polyurethane (A) in the conductive composition (D);
A conductive paint (F) comprising: A conductive fiber material (G) obtained by coating the conductive composition (D) according to claim 1 on a fiber material (g). A method for producing a conductive fiber material (G), comprising applying the conductive paint (F) according to claim 2 to the fiber material (g). A planar heating element (H) comprising the conductive fiber material (G) according to claim 3.

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