JP2011134527A - Sheet heating element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet heating element in which the edge rupture of PTC conductive ink does not occur, and in which a resistor evenly generates heat. <P>SOLUTION: The sheet heating element includes: an electric insulating substrate 3a; a plurality of thin-wall and high-conductive electrode blocks 2a, 2b formed on the substrate 3a; and the resistor 6 formed to be connected with the electrode blocks 2a, 2b by coating and drying. The resistor 6 forms the predetermined conductive resistor 6 by the coating and drying, the resistor is resistor paste showing electrical insulation properties before coating and adds a conductive application agent for applying conductive properties to merely prevent an electric charge in the resistor paste. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a planar heating element used for, for example, an electric floor heating panel and an electric carpet, and more particularly to a planar heating element in which electrodes and resistors are formed by coating and drying.

  Conventionally, as shown in FIG. 5, this type of planar heating element 21 includes a pair of conductive buses 23a and 23b obtained by printing a conductive silver polymer on an electrically insulating substrate 22 such as a polyester film and the like. Conductor passages 24a and 24b that extend vertically from the bus bars 23a and 23b and are parallel and spaced apart from each other to form comb-shaped electrodes are provided, and PTC conductive ink is provided thereon as shown in FIG. , 24b is printed and dried to form the resistor 25. As a result, the heating region 26 is formed between the conductor passages 24a, 24b.

  The PTC conductive ink that forms the heating region 26 is obtained by adding carbon black to an ethylene vinyl acetate copolymer resin (hereinafter referred to as EVA resin) and mixing it with a solvent to form an ink (see, for example, Patent Document 1).

  There are various printing methods such as gravure printing, letterpress printing, screen printing, etc., but screen printing is desirable for this type of sheet heating element 21 because of the freedom of the printing pattern and the printing thickness.

  In the screen printing, as shown in FIG. 7, pressure is applied so that the ink 41 placed on the screen plate 40 is pushed into the screen plate 40 by a rubber plate called a squeegee 42. In this state, the squeegee 42 moves, and the squeegee moves. This is a printing method in which the screen 43 of the screen plate 40 is gradually separated after the movement of 42 and is attached to the electrically insulating substrate 22 through the fine holes (mesh) constituting the printing pattern provided on the screen plate 40.

  The PTC characteristic is a resistance temperature characteristic in which the resistance value increases as the temperature rises, and when the temperature reaches a certain temperature, the resistance value rapidly increases (takes the initial letter of English Positive Temperature Coefficient, which means that the resistance has a positive temperature coefficient) The heating region having the PTC characteristic can provide a planar heating element having a self-temperature adjusting function.

Japanese Patent Laid-Open No. 3-129893

  In the conventional sheet heating element 21, as described above, when the PTC conductive ink is printed by screen printing so as to cover the conductor paths 24a and 24b, for example, on the edge portion 27 of the conductor path 24a as shown in FIG. A slit-shaped tear 29 in the heating region 26 may occur. When dried in this state, the resistor 25 and the conductor passages 24a and 24b are not physically and electrically connected. Therefore, the heating region 26 where the tear 29 is generated does not generate heat, and the tear 29 is large. When the connecting portion 30 with the 24b is small, there is a problem that abnormal heat generation occurs because current concentrates on the connecting portion 30.

  Various causes for the generation of the tear 29 are conceivable and cannot be uniquely determined. One of them is charging by static electricity.

  For example, it is well known that when an ebonite bar is rubbed with a cloth, the ebonite bar is charged by static electricity. In addition, the liquid and gas flowing in the pipe, the liquid and gas passing through the filter are also charged by rubbing between the pipe and the liquid, or rubbing between the filter and the liquid and gas.

  Similarly, in screen printing, the squeegee 42 is moved while being pressed against the screen plate 40, so frictional charging occurs between the squeegee 42 and the screen plate 40. At that time, since the screen plate 40 and the electrically insulating substrate 22 are in contact with each other at the portion where the squeegee 42 is pressed against the screen plate 40, the electrically insulating substrate 22 is also charged. In particular, the conductor passages 24a and 24b that have been printed and dried in advance on the electrically insulating substrate 22 are conductors, but the conductive buses 23a and 23b and the conductor passages 24a and 24b are not grounded. Due to the electric effect, the amount of charge is larger than the portion where the conductive buses 23a, 23b and the conductor passages 24a, 24b on the electrically insulating substrate 22 are not printed or dried.

  The meaning of the conductivity of the PTC conductive ink is that the mixture of EVA resin and carbon black remains after printing and drying, and carbon black forms a conductive path. In the ink state, the EVA resin and Since the conductive path by carbon black is not formed when the carbon black particles are floating, the ink is an electrical insulator. Therefore, the PTC conductive ink is also charged.

  If the sheet heating element 21 is stationary on the printing base 44 after screen printing of PTC conductive ink, the electrically insulating substrate 22, the conductive buses 23a and 23b, and the conductor passages 24a and 24b are PTC conductive. Even if the ink is charged, the surface of each member is in the state of an electric double layer in which (−) charges and (+) charges are mixed, and it appears to be uncharged.

  However, at the moment when the sheet heating element 21 is separated from the printing base 44 for drying, the (−) charge and the (+) charge move. Although the movement direction of the (−) charge and the (+) charge is not certain, for example, if the (+) charge moves to the printing opposite surface of the electrically insulating substrate 22, the printing surface, ie, the conductive paths 24 a and 24 b ( -) Charge moves and (-) charges, (+) charges move to the PTC conductive ink solvent and (+) charges, and (-) charges move to the EVA resin and carbon black particles ( -) It will be charged.

  Therefore, while the sheet heating element 21 is placed on the printing base 44, the PTC conductive ink is adhered so as to cover the conductive paths 24a and 24b. When separated, the EVA resin and the carbon black particles are separated from the edge portions 27 of the conductive passages 24a and 24b by electric repulsion. As a result, a tear 29 is generated.

  The tear 29 does not necessarily occur in all of the conductive passages 24a and 24b, but may occur partially, because the electric charges move uniformly in all of the conductive passages 24a and 24b and are not uniformly charged. Further, it is considered that the PTC conductive ink is not uniformly charged. In particular, when the sheet heating element 21 is separated from the printing base 44, if one of the conductive paths 24a leaves at the end, the charge concentrates on the one conductive path 24a. A tear 29 is likely to occur in the portion.

Further, in screen printing, the ink film thickness varies depending on the pressure (hereinafter referred to as printing pressure) for pressing the squeegee 42 against the screen plate 40, and this variation in film thickness can be obtained by printing and drying the PTC conductive ink. The resistance value of the resistor 25 to be changed also varies.

  That is, if the printing pressure is weak, the ink film thickness is thick and the resistance value of the resistor 25 is low. If the printing pressure is strong, the ink film thickness is thin and the resistance value of the resistor 25 is high. Therefore, even if the specific resistance of the PTC conductive ink varies, the sheet heating element 21 can be adjusted to a predetermined resistance value range by adjusting the printing pressure. If 29 is generated at a low printing pressure, the resistance value of the sheet heating element 21 cannot be adjusted, which causes a serious hindrance to the production of the sheet heating element 21.

  Further, in the sheet heating element 21, when the conductive buses 23a and 23b and the conductive paths 24a and 24b are separately printed, and the PTC conductive ink is printed after the conductive paths 24a and 24b are printed and dried, or 9, the PTC conductive ink 33 is printed so as to cover the electrodes 32a and 32b formed on the electrically insulating substrate 34, and a large number of small planar heating elements 31 are produced by one printing. In such a case, since the electrodes 32a and 32b are completely independent, there is a large variation in the charge amount, the probability of the occurrence of a tear at the edge portion is increased, and the number of occurrences is increased. In the case of the planar heating element shown in FIG. 5, if the conductive buses 23a and 23b and the respective conductive passages 24a and 24b are formed at the same time, the electric charges generated in the respective conductive passages 24a and 24b are transferred to the conductive bus 23a, 23b, it moves to some extent, so that it is possible to suppress variation in the charge amount of each of the conductive paths 24a, 24b, although it is not uniform as described above. However, if the conductive paths 24a, 24b are independent, Therefore, the variation in the charge amount is large with the conductive path having a large charge amount and the conductive path having a small charge amount as they are.

  The present invention solves the problems that occur in the conventional sheet heating element, and provides a sheet heating element in which the PTC conductive ink does not break at the edge portion and the resistor heats uniformly. With the goal.

  In order to solve the above problems, the present invention has been repeated through various trials and errors.

  That is, the planar heating element of the present invention is applied to an electrically insulating substrate, a plurality of thin and highly conductive electrode blocks formed on the electrically insulating substrate, and connected to the electrode block. A resistor formed by drying, and the resistor is a resistor paste that exhibits electrical insulation before application, and the resistor paste is provided with conductivity sufficient to prevent at least charging. A property imparting agent is added, and a predetermined conductive resistor is formed by coating and drying.

  Therefore, when the resistor paste is applied so as to cover the edge portion of the electrode block, the resistor paste is added with a conductivity-imparting agent that imparts conductivity sufficient to prevent charging. The amount of charge is extremely small, there is no electrical repulsion at the edge of the electrode block, no slit-like rift occurs, and there is no problem with the resistor not generating heat or partially generating abnormal heat. The planar heating element can generate heat uniformly.

  According to the planar heating element of the present invention, since the conductivity imparting agent that imparts at least conductivity only to prevent charging is added to the resistor paste, the charge amount of the resistor paste becomes extremely small, and the electrode block There is no electrical repulsion at the edge of the wire, no slit-like rift occurs, and there is no problem that the resistor does not generate heat or abnormal heat is partially generated, and the sheet heating element generates heat uniformly. can do.

The top view which shows the structure of the planar heating element in Embodiment 1 of this invention (A), (b) The figure which shows the manufacture procedure of the planar heating element in Embodiment 1 The top view which shows the structure of the planar heating element in Embodiment 2 of this invention (A), (b), (c) The figure which shows the manufacture procedure of the planar heating element in Embodiment 2 Plan view of a conventional planar heating element Partial sectional view of a conventional sheet heating element Explanatory drawing of screen printing of conventional sheet heating element Sectional view of printing state of a conventional sheet heating element Plan view of another conventional sheet heating element

  The first invention is formed by applying and drying an electrically insulating substrate, a plurality of thin and highly conductive electrode blocks formed on the electrically insulating substrate, and connected to the electrode block. The resistor is a resistor paste that exhibits electrical insulation before application, and a conductivity-imparting agent that imparts at least conductivity sufficient to prevent charging is added to the resistor paste. Thus, a predetermined conductive resistor is formed by coating and drying.

  As a result, when the resistor paste is applied so as to cover the edge portion of the electrode block, the resistor paste is added with a conductivity-imparting agent that imparts conductivity sufficient to prevent charging. The amount of electrification of the electrode becomes extremely small, there is no electrical repulsion at the edge of the electrode block, no slit-like rift occurs, and there is no problem that the resistor does not generate heat or that abnormal heat generation occurs partially. In other words, the planar heating element can generate heat uniformly.

  According to a second aspect of the invention, particularly in the first aspect of the invention, the plurality of electrode blocks are electrically connected to the connection electrodes without being connected to the plurality of connection electrodes respectively connected to the resistors. The power supply electrode is formed after the application / drying of the resistor paste is formed.

  Thereby, in addition to the effect in 1st invention, since the connection electrode connected with a resistor is independent one by one and can be formed separately from a feed electrode, it can be formed thinner than a feed electrode, The amount of charge due to static electricity of the connection electrode to which the resistor paste is applied can be reduced. In addition, a large number of small planar heating elements can be produced at a time, and production efficiency can be improved.

  In the third invention, the resistor paste of the first or second invention is applied by screen printing.

  Thereby, in addition to the effects in the first or second invention, the printing pressure of the squeegee with respect to the screen plate can be adjusted, so that the charged amount of the printed resistor paste due to static electricity can be reduced.

  Embodiments of the present invention will be described below. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
The first embodiment will be described with reference to FIGS.

Resistor paste to be the resistor 6 is prepared by preparing a crystalline resin, for example, ethylene vinyl acetate copolymer and carbon black, and kneading with a heating mixing roll machine to sufficiently disperse the carbon black to prepare a conductive composition. Then, this conductive composition was prepared by adding an imidazoline-based surfactant as a conductivity-imparting agent while dissolving it in a paste using an aromatic hydrocarbon solvent.

  In addition, as a comparative sample, a crystalline resin such as an ethylene vinyl acetate copolymer and carbon black is prepared, and kneaded with a heating mixing roll machine to sufficiently disperse the carbon black to create a conductive composition. This conductive composition was dissolved in a paste using an aromatic hydrocarbon solvent to prepare a resistor paste.

  About the two types of resistor pastes, volume resistivity was measured using an electrometer 8340A manufactured by ADC Co., Ltd.

As a result, the resistor paste of the comparative sample was 4 × 10 ¹² Ω-m, whereas the resistor paste of the present invention was 3 × 10 ⁹ Ω-m. Therefore, it was confirmed that the resistor paste of the present invention was given conductivity because of its lower volume resistivity.

  Here, the manufacturing process of the planar heating element 1b of the present embodiment will be described with reference to FIG. First, as shown in FIG. 2A, electrode blocks 2a and 2b are formed in advance on the electrically insulating substrate 3a. Next, as shown in FIG. The resistor paste is printed so as to cover the conductor paths 2a-2 and 2b-2 branched from the conductive buses 2a-1 and 2b-1, and dried.

  For printing, a LS-150 screen printer manufactured by Neurong Co., Ltd. was used, and screen printing was performed on a PET film electrically insulating substrate 3a on which electrode blocks 2a and 2b as shown in FIG. The resistor 6 was formed by drying in a hot air drying furnace at 30 ° C. for 30 minutes, and the planar heating element 1a was produced.

  As printing conditions, the printing pressure was changed in five types: 5N, 13N, 20N, 28N, and 35N. (If the printing pressure is 5N or less, a lot of micro holes are generated on the ink printing surface, and if it is 35N or more, the ink printing surface is faded.) The printing pressure can be obtained by using a PET film strip with a width of about 5 cm. It is indicated by the tensile force when sandwiched between plates and pulled.

  The presence or absence of a tear at the edge was determined visually.

  As a result, the sheet-like heating element obtained by printing / drying the resistor paste of the comparative sample generated a tear at the edge at printing pressures of 28N and 35N, and a groove-like streak was observed at 20N, although it was not a tear. On the other hand, the sheet heating element obtained by printing and drying the resistor paste of the present invention did not generate edge tears or groove-like streaks for all printing pressures from 5N to 35N.

  About the planar heating element comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  The imidazoline-based surfactant that is a conductivity-imparting agent is present in the aromatic hydrocarbon solvent and around the conductive composition, and the volume resistivity appears lower than that of the conventional resistor paste. It is thought that it is ionized.

  After the resistor paste of the present invention is printed, the planar heating element is moved for drying. At that time, the charge charged by static electricity moves as described above. However, the imidazoline-based surfactant, which is an ionized conductivity imparting agent, absorbs electric charge and reduces the amount of charge, so that the gap between the edge portions 5a and 5b of the electrode blocks 2a and 2b and the conductive composition is reduced. No electrical repulsion occurs and no tears occur.

  In the present embodiment, even when a conventional heating element printed and dried with a resistor ink is used, the edge portion is not cracked at a weak printing pressure of 5N or 13N because of the relationship between the charge amount and the film thickness. When the printing pressure is weak, the amount of charge is small and the film thickness is thick. Therefore, the filling force to the edge portions 5a and 5b by the weight of the resistor paste on the edge portions 5a and 5b is more than the electric repulsive force. It is presumed that there will be no wins and tears.

(Embodiment 2)
As the resistor paste, the same resistor paste of the present invention as that of the first embodiment and a conventional resistor paste for comparison were used for printing.

  Here, the manufacturing process of the planar heating element 1b of the present embodiment will be described with reference to FIG. First, as shown in FIG. 4A, a plurality of connection electrodes 4 are formed in advance at equal intervals on the electrically insulating substrate 3a, and then, as shown in FIG. 4B, the connection electrodes 4 are formed. It is printed so that the resistor paste is covered, leaving the edge of and dried. Thereafter, as shown in FIG. 4C, the connection electrodes 4 are alternately connected by the two power supply electrodes 7a and 7b, thereby completing the planar heating element 1b.

  The printing was performed using a LS-150 type screen printer manufactured by Neurong Co., as in the first embodiment, but screen printing was performed on a PET film 3b on which connection electrodes 4 as shown in FIG. The sheet-like heating element 1b was produced by drying in a hot air drying furnace for 30 minutes.

  As in the first embodiment, the printing conditions were changed to five types of printing pressures of 5N, 13N, 20N, 28N, and 35N.

  The presence or absence of a tear at the edge was also judged visually.

  As a result, the sheet heating element obtained by printing and drying the resistor paste of the comparative sample generated a tear at the edge at printing pressures of 20N, 28N, and 35N, and a groove-shaped streak was observed at 13N, although it was not a tear. It was.

  The reason why crevices and groove-like streaks are generated with a weaker printing pressure than in the first embodiment is that the connection electrodes 4 are independent, so that charge cannot move between the connection electrodes 4. It seems that the connection electrode 4 having a large amount of charge, that is, a large amount of charge, has crevices and groove-like streaks.

  On the other hand, the sheet heating element obtained by printing and drying the resistor paste of the present invention did not generate edge tears or groove-like streaks for all printing pressures from 5N to 35N.

  About the planar heating element comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  The imidazoline-based surfactant that is a conductivity-imparting agent is present in the aromatic hydrocarbon solvent and around the conductive composition, and the volume resistivity appears lower than that of the conventional resistor paste. It is thought that it is ionized.

  After printing the resistor paste of the present invention, the planar heating element is moved for drying. At that time, as described above, the charge charged by static electricity moves. However, the imidazoline-based surfactant, which is an ionized conductivity imparting agent, absorbs electric charge and reduces the amount of charge, so that the electric repulsion between the edge portion of the connection electrode 4 and the conductive composition. Will not occur and no tear will occur.

  In the first and second embodiments of the present invention, an imidazoline-based surfactant is used as the conductivity-imparting agent, but it is not limited as long as it is a material that is ionized in the solvent constituting the resistor paste. .

  In Embodiments 1 and 2 of the present invention, screen printing is adopted. However, in other printing methods, the resistor paste of the present invention can be used as long as static electricity is generated and charged during printing. It is valid.

  As described above, the planar heating element according to the present invention is applied and dried so as to be connected to the electrically insulating substrate, the plurality of thin and highly conductive electrode blocks formed on the substrate, and the electrode blocks. The resistor forms a predetermined conductive resistor by coating and drying, and is a resistor paste that exhibits electrical insulation before coating, and the resistor paste is at least charged. Since a conductivity-imparting agent that imparts conductivity that prevents the resistance is added, the amount of charge of the resistor paste becomes extremely small, there is no electrical repulsion at the edge of the electrode block, and the slit-shaped tear is There is no problem that the resistor does not generate heat or abnormal heat is partially generated, and the sheet heating element can generate heat uniformly, so floor heating panels, electric carpets, etc. of Not limited to tufts products, the resistor surface to form, can be applied to the heating element every placing the power supply electrodes.

DESCRIPTION OF SYMBOLS 1a, 1b Planar heating element 2a, 2b Electrode block 3a, 3b Electrically insulating board | substrate 4 Connection electrode 5a, 5b Edge part 6 Resistor 7a, 7b Feed electrode

Claims (3)

An electrically insulating substrate; a plurality of thin and highly conductive electrode blocks formed on the electrically insulating substrate; and a resistor formed by applying and drying so as to connect to the electrode block. The resistor is a resistor paste that exhibits electrical insulation before coating, and is formed by adding a conductivity imparting agent that imparts at least conductivity sufficient to prevent charging to the resistor paste. A planar heating element that forms a predetermined conductive resistor by drying. Each of the plurality of electrode blocks includes a plurality of connection electrodes that are connected to a resistor, and a power supply electrode that is not connected to the resistor and is electrically connected to the connection electrode. The planar heating element according to claim 1, which is formed after the body paste is applied and dried. The planar heating element according to claim 1 or 2, wherein the resistor paste is applied by screen printing.