JP3032839B2 - Planar heating element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar heating element which generates heat when energized, and more particularly, to a sheet heating element which can be easily manufactured by applying a coating for a heating resistor to an insulating substrate, and is used for heating and heating.
The present invention relates to a planar heating element that can be used for raising seedlings, melting snow, icing, preventing dew condensation, and the like.

[0002]

2. Description of the Related Art In recent years, it is easier to manufacture as compared with a planar heating element using a heating material such as a nichrome wire, the temperature distribution on the surface of the heating element is uniform, and if necessary, Since the heating element itself can have a self-temperature control function, a planar heating element in which a heating resistor paint is applied to an insulating substrate has been widely studied. These planar heating elements are manufactured by applying a coating for a heating resistor composed of a resin component and a conductive filler to an insulating substrate. For example, JP-A-55-134229 and JP-A-56-134229 disclose the surface heating elements. 53
No. 781 and JP-A-63-110590,
Japanese Patent Application Laid-Open Nos. Sho 55-96591, Sho 57-11489, and Sho 63-133480 disclose a planar heating element coated with a coating for a heating resistor containing conductive carbon black or graphite. Ni, A
A planar heating element to which a coating for a heating resistor containing a metal powder such as g or Fe is applied has been proposed.

[0003] However, a sheet heating element coated with a coating for a heating resistor containing the above-mentioned conductive carbon black or graphite uses carbon black or graphite having a high electric resistivity as a conductive filler, so that it cannot be obtained. The volume resistivity of the sheet heating element to be used is too high, so that a high voltage is required or the distance between the electrodes cannot be increased in order to obtain desired heat generation. On the other hand, the sheet heating element using the metal powder as the conductive filler, since the metal itself has a high specific gravity, in the coating for the heating resistor, the metal powder is likely to settle, producing a sheet heating element. It is difficult to control the coating process at the time. In addition, since the generally used metal powder is fine spherical particles, in order to obtain a desired volume resistivity, the content ratio of the metal powder is increased in the content ratio of the metal powder and the resin binder. Because of the necessity, it is difficult to decrease the physical strength of the coating film for the heating resistor and to gradually change the low resistance value. In addition, there are disadvantages such as being economically disadvantageous because a large amount of expensive metal powder is used.

JP-A-48-101455 discloses a conductive plastic composite made of a thermosetting and / or thermoplastic resin containing a fine hollow body of glass or plastic having a metal coating. It has been shown that the shape of the micro hollow body may be any shape such as a spherical shape, an elliptical spherical shape, a rod shape and the like, and that the conductive plastic composite can be used as a surface heating element.

[0005] The micro hollow body is excellent in dispersibility in the resin because it is lighter in weight than the resin component, but because it is spherical, it is dispersed in the resin component even if it is elliptical spherical or the like. In such a case, the contact between the micro hollow bodies becomes a point contact. Therefore, when used as a coating film having almost only a secondary directional property, it is necessary to ensure sufficient and uniform conductivity and durability for conducting electricity. However, since it is a hollow body, there is a problem in strength.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sheet heating element which is easy and inexpensive to manufacture and can generate heat at a low voltage.

[0007] Another object of the present invention is to provide a coating film having sufficient and uniform conductivity and current-carrying durability, and at the same time having excellent smoothness of the coating film, even in a coating film having almost only a secondary orientation. To provide a heating element in the form of a plate.

[0008]

According to the present invention, there is provided a flat metal plating powder having an average diameter of 5 to 100 μm and a thickness of 0.01 to 20 μm per 100 parts by weight of a resin solid content.
A sheet heating element is provided, in which a coating for a heating resistor containing 50 parts by weight is applied to an insulating substrate provided with a strip electrode to form a coating for the heating resistor.

Hereinafter, the present invention will be described in more detail. The planar heating element of the present invention is obtained by applying a specific flat metal plating powder and a coating for a heating resistor containing a resin component to an insulating substrate having strip electrodes to form a heating resistor coating film. It is characterized by becoming.

The flat metal plating powder used in the present invention comprises:
Compared to the conductive filler used in the conventional sheet heating element, it is a component that improves the conductivity and smoothness of the sheet heating element, and can reduce the weight and cost, and will be described later. It is excellent in dispersibility in a resin component, and in the resin component, each flat metal plating powder has a flat surface that comes into contact by surface contact. Therefore, it does not include a shape that comes into contact only with point contact, such as a spherical shape such as an elliptical shape.

Examples of the base material constituting the flat metal plating powder include sericite, muscovite, phlogopite, glass and plastic flakes. The plating metal includes nickel, copper, silver and the like. And a metal selected from the group consisting of multilayers and alloys thereof. Further, the flat metal plating powder,
It can be easily obtained by a known method, for example, an electroless plating method described in JP-A-59-78248. The size of the flat metal plating powder has an average diameter of 5 to 100.
μm and a thickness of 0.01 to 20 μm. When the average diameter is less than 5 μm, the surface area becomes too large, the amount of coated metal increases, the specific gravity of the obtained powder increases, and furthermore, there is a problem economically. The average particle size is 1
If it exceeds 00 μm, the surface smoothness of the obtained planar heating element is impaired. Further, when the thickness is less than 0.01 μm,
Since the physical strength of the powder itself is reduced, the strength of the heating resistor coating film is reduced, and when the thickness exceeds 20 μm, the properties as a flat metal powder are lost. As a result,
A sheet heating element exhibiting good heat generation with a small content cannot be obtained.

The resin component used in the paint for a heat generating resistor of the present invention is preferably a crosslinkable resin or the like in order to maintain long-term durability in terms of physical properties and chemical properties. The resin component does not include a crystalline resin.

Examples of the crosslinkable resin include reactive resins and the like generally used in paints, and may be used in combination with various curing agents as required. Specific examples of the crosslinkable resin include, for example, an unsaturated group, a hydroxyl group, a carboxyl group, an ester group, an N-methylol group,
Polyester resin containing amino group, epoxy group, etc.
An acrylic resin, an alkyd resin, an epoxy resin, a silicone resin, a phenol resin, and the like can be given.

Examples of the curing agent include an amino-plast resin, an isocyanate compound, a blocked isocyanate compound, a polyamine compound and a polycarboxylic acid compound. When used, they can be used alone or as a mixture.

The mixing ratio of the flat metal plating powder and the resin component in the heating resistor paint used in the present invention is such that the flat metal plating powder is 40 to 40 parts by weight per 100 parts by weight of the solid content of the resin component. It is necessary to mix the amount so as to be in the range of 150 parts by weight. The compounding ratio of the flat metal plating powder is 40
If the amount is less than 150 parts by weight, the conductivity is reduced. If the amount is more than 150 parts by weight, the conductivity is increased, which is unsuitable as a sheet heating element and the strength of the coating film is reduced. In general, it is preferable to adjust the volume resistivity of the conductive film, that is, the coating film for a heating resistor when used as a planar heating element, in the range of 0.001 Ω · cm or more and less than 1 Ω · cm.

In order to prepare the paint for a heating resistor used in the present invention, the flat metal plating powder and a resin component can be obtained by the same method as a usual paint. It can be in the form of a non-aqueous dispersion type, a water-soluble type or an emulsion type. If necessary, various coloring agents, additives and the like usually used for paints can be added in addition to the above components.

In the present invention, an insulating substrate provided with strip electrodes is used as a substrate for applying the paint for the heating resistor. As the insulating substrate, plastic, concrete, wood, slate, glass, ceramics, paper, metal coated with insulating coating, or the like can be used. Examples of the strip electrode provided on the insulating substrate include a metal tape such as copper or silver, a wire net, and a conductive paste. To install the strip electrode on the insulating substrate, before applying the coating for the heating resistor, a pair or more strip electrodes,
It can be placed on an insulating substrate in advance, or after applying and curing a coating for a heating resistor on the insulating substrate, and then bonding and placing it on the obtained coating film with an adhesive or heat and pressure.

In order to manufacture the sheet heating element of the present invention, a coating for a heating resistor is applied to one or both surfaces of the insulating substrate by, for example, dip coating, spray coating, roll coating or print coating. It can be obtained by curing by a curing method according to the type of the curing agent to be used and forming a coating film for a heating resistor. The thickness of the heating resistor coating film is not particularly limited, but 10 to 500 μm
It is preferred that Further, in order to increase the durability of the sheet heating element or to impart aesthetics, it is possible to further apply a normal paint on the coating film for the heating resistor.

[0019]

The planar heating element of the present invention uses a specific flat metal plating powder, and each of the flat metal plating powders has a flat surface for surface contact, that is, a flat surface. Since it is a lightweight material having a surface and being plated with metal, it is well dispersed in the resin component, and is arranged in the horizontal direction, so that the smoothness and the strength of the coating film are improved. Therefore, the production of the sheet heating element itself is easy and inexpensive, and heat can be generated by a low voltage. Therefore, it is useful for applications such as heating, raising seedlings, melting snow, preventing icing or condensation.

[0020]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0021]

[Example 1] Ni-plated sericite (trade name "META")
L-ON, NSER-6 "average diameter 30μm, thickness 3μ
m, metal content 30% by weight, manufactured by Nisso Metal Chemical Co., Ltd.)
29.6 g was put into 58.7 g of an acrylic resin paint (trade name “High Urethane No. 5000 Clear 51HA”, solid content: 40.8% by weight, manufactured by NOF CORPORATION), and stirred for 30 minutes with a dissolver. Curing agent (trade name "High urethane curing agent HA" manufactured by NOF CORPORATION, solid content 48)
11.7 g). Then, using a diluted thinner (trade name: "Urethane Thinner W", manufactured by NOF CORPORATION), Ford Cup # 4 was diluted to a viscosity of 15 seconds to obtain a paint for a heating resistor. The content of the Ni-plated sericite powder in the obtained paint was 100 parts by weight based on 100 parts by weight of the paint resin solids. Next, on a dull steel plate (JIS G3141) having a width of 5 cm, an insulating coating film (trade name “Epico No. 1500, TX-10
0 "manufactured by Nippon Oil & Fat Co., Ltd.) and two conductive tapes (trade name" Scotch conductive tape No. 2245 "manufactured by Sumitomo 3M Limited) having a length of 5 cm are formed on the insulating substrate. The conductive tape was stuck so that the distance between the conductive tapes became 10 cm. On the insulating substrate provided with the obtained conductive tape, the coating for a heating resistor was applied with a dry film thickness of 100 μm.
m, then spray paint at 140 ° C
After baking and drying for 0 minutes, a sheet heating element was obtained.

The volume specific resistance of the obtained sheet heating element is:
It was 0.02 Ω · cm. When the heating element was energized with an alternating current of 5 V, the surface temperature was 60 ° C. (outside air temperature was 20 ° C.). A durability test was performed on the obtained sheet heating element according to the method described below. Table 1 shows the results.

The durability of the sheet heating element was measured by setting a cycle of 2 hours at a direct current of 10 V and 30 minutes of a power outage as one cycle.

Thermal cooling cycle test --The sheet heating element was left in an environment of 1 cycle at -30 ° C., 0.5 hour at 20 ° C., 1 hour at 80 ° C., and 0.5 hour at 20 ° C. And the durability due to thermal shock was measured.

[0025]

[Table 1]

[0026]

Example 2 A planar heating element was manufactured in the same manner as in Example 1, except that 21.8 parts by weight of Ni-plated sericite, 65.1 parts by weight of an acrylic resin paint, and 13.1 parts by weight of a curing agent were used. At this time, the content of Ni-plated sericite was 66.7 parts by weight based on 100 parts by weight of the resin solid content in the heating resistor coating film.

The volume resistivity of the obtained sheet heating element is:
It was 0.17 Ω · cm. This planar heating element has an AC 1
The surface temperature became 68 ° C. (outside air temperature 20 ° C.) by applying 0V.

[0028]

Example 3 Cu-plated sericite (average diameter 30 μm,
3 μm thick, metal content 20% by weight, trade name “META
L-ON, CSER-4 "manufactured by Nisso Metal Chemical Co., Ltd.) 2
Except for using 9.6% by weight, 58.6% by weight of an acrylic resin coating and 11.8% by weight of a curing agent, a coating for a heating resistor was prepared in the same manner as in Example 1. In the obtained paint, the content of the Cu-plated sericite powder was 100 parts by weight based on 100 parts by weight of the paint resin solids. Next, two 4 cm long conductive tapes (trade name “Scotch conductive tape No. 2245” manufactured by Sumitomo 3M Limited) were placed on a 4 cm wide glass plate (2 mm thick) with a spacing of 7 cm between the conductive tapes. It stuck so that it might become. On the insulating substrate provided with the obtained conductive tape, the paint for a heating resistor is applied with a dry film thickness of 10
140 ° C after air spray coating to 0μm
For 30 minutes to obtain a sheet heating element.

The volume resistivity value of the obtained sheet heating element is:
It was 0.18 Ω · cm. This planar heating element has an AC of 7
The surface temperature became 62 ° C. (outside air temperature 20 ° C.) by the application of V. Furthermore, even if the energization is performed continuously for 24 hours,
No change was observed in the exothermic temperature and the volume specific resistance.

[0030]

Example 4 5 cm length on a 5 cm wide oxygen plasma surface treated heat resistant polypropylene plate (pp / mica composite)
m conductive tape (Product name "Scotch conductive tape No.2
245 "(manufactured by Sumitomo 3M Limited) so that the distance between the conductive tapes was 10 cm. Next, the paint for a heating resistor prepared in Example 1 was applied by air spray coating on the insulating substrate provided with the obtained conductive tape so that the dry film thickness became 100 μm, and then baked and dried at 120 ° C. for 1 hour. Thus, a sheet heating element was obtained.

The volume resistivity value of the obtained sheet heating element is:
It was 0.02 Ω · cm. This planar heating element has an alternating current of 3
With the application of V, the surface temperature became 56 ° C. (outside air temperature 2
0 ° C). Next, a durability test of the sheet heating element was performed in the same manner as in Example 1. Table 2 shows the results.

[0032]

Embodiment 5 Instead of a heat-resistant polypropylene plate, width 4c
m, a conductive tape interval of 5 cm, and a baking condition of the heating resistor paint at 140 ° C. of 3 cm.
A sheet heating element was manufactured in the same manner as in Example 4, except that the time was set to 0 minutes.

The volume resistivity of the obtained sheet heating element is:
0.02 Ω · cm, and the surface temperature of the sheet heating element when 5 V AC was supplied was 58 ° C. (outside air temperature: 20 ° C.). Next, a durability test of the sheet heating element was performed in the same manner as in Example 1.
Table 2 shows the results.

[0034]

[Table 2]

[0035]

Embodiment 6 Ni-plated sericite (trade name “META”)
L-ON, NSER-6 "average particle size 30μm, thickness 3μ
m, metal content 30 wt%, manufactured by Nisso Metal Chemical Co., Ltd.) 5
0.0 parts by weight, epoxy resin paint (trade name “Epomic R-140” manufactured by NOF Corporation, solid content 100% by weight)
33.5 parts by weight, a curing agent (trade name "EPOMIC Q-61")
0 "manufactured by NOF Corporation, solid content 100% by weight) 16.5
A coating for a heating resistor in parts by weight was prepared in the same manner as in Example 1, and then applied to a glass plate provided with the conductive tape manufactured in Example 3 using an applicator so that the dry film thickness became 100 μm. Next, baking and drying were performed at 140 ° C. for 30 minutes to obtain a sheet heating element.

The volume resistivity of the obtained sheet heating element was 0.05 Ω · cm, and the surface temperature of the sheet heating element by applying a current of 3 V was 45 ° C. (outside air temperature: 20 ° C.).

[0037]

Example 7 A white paint (base resin, base material, viscosity of Ford cup # 4 adjusted to 20 seconds) was applied on the sheet heating element prepared in Example 1.
Product name "Primac, No. 4000 White 41P
B ", a curing agent" Primac curing agent PB ", a main agent / curing agent ratio of 4/1 (wt%), manufactured by NOF CORPORATION), followed by baking and drying at 120C for 30 minutes. At this time, the thickness of the white paint was 40 μm.

The volume resistivity value of the obtained sheet heating element was 0.02 Ω · cm, and the surface temperature of the sheet heating element by applying 5 V AC was 59 ° C. Therefore, it was found that there was no problem even if further overcoating was performed on the sheet heating element.

[0039]

Comparative Examples 1 to 3 Coatings having the formulations shown in Table 3 were prepared in the same manner as in Example 1, and then applied to the same insulating substrate as in Example 1 to obtain Ni flake-containing heating elements.

Table 3 shows the results of applying an alternating current of 10 V to the obtained Ni flake-containing heating element. From the results in Table 3, it was found that when Ni flakes were used, the amount of Ni flakes required exceeded 150 parts by weight based on 100 parts by weight of the resin solid content in order for the heating element to generate heat satisfactorily.

[0041]

[Table 3]

[0042]

Comparative Example 4 Conductive carbon (trade name “CONDUCT”)
EX975BEADS ", 7.6 g of Columbian Carbon Japan Co., Ltd., acrylic resin paint (trade name" Hiurethane No. 5000 Clear 51HA main agent "manufactured by NOF Corporation, solid content 40.8% by weight) 36. 3 g and 56.1 g of xylene were mixed, stirred with a dissolver for 30 minutes, and then dispersed with a grind mill for 30 minutes. Then
93.2 g of the obtained dispersion and a curing agent (trade name "urethane curing agent HA" manufactured by NOF Corporation, solid content 48% by weight)
And 6.8 g of a coating material containing a maximum amount of conductive carbon (30% by weight).

Next, the obtained conductive carbon-containing paint was applied by air spraying to a glass plate provided with the conductive tape prepared in Example 3 so as to have a film thickness of 60 μm, and then baked and dried at 140 ° C. for 30 minutes. Thus, a sheet heating element was obtained.
The volume solid resistance value of the obtained sheet heating element is 0.60Ω · c.
m. Further, the surface temperature of the sheet heating element by applying a current of 40 V AC was 44 ° C. Therefore, it was found that when conductive carbon was used, the applied voltage had to be higher than that of the planar heating element of the present invention.

[0044]

[Comparative Example 5] A product name "Shirasu Balloon PB-02" (manufactured by SILAX CORPORATION, particle size distribution: 5-105 µm)
Those having a size of more than 30 μm were removed by using a sieve to obtain a sialal balloon having a particle size distribution of 5 to 30 μm. Next, the obtained shirasu balloon was washed with water, immersed in an aqueous solution of stannous chloride, sensitized, immersed in a Ni plating solution, and subjected to a chemical plating treatment at a temperature of 60 ° C. for 30 minutes to obtain Ni. A plated shirasu balloon (average diameter 16 μm) was prepared. The obtained Ni-plated shirasu balloon was replaced with Ni in Example 1.
A planar heating element was obtained in the same manner as in Example 1, except that the plating sericite powder was used instead of the plated sericite powder, and a similar test was performed. In order to make the surface temperature of the obtained planar heating element 60 ° C.,
Electric current of 11.0 V AC was required. The current durability test is
The test was performed at DC 20V. Table 4 shows the results. In both the current durability test and the thermal cycle test, the conductivity was lost in a short time, and it was found that the heating element formed by point contact with spherical particles could not withstand long-term use.

[0045]

[Table 4]

[0046]

Comparative Example 6 A planar heating element was produced in the same manner as in Example 1 except that the average diameter of the Ni-plated sericite in Example 1 was changed to 246 μm.

The surface of the coating film of the obtained sheet heating element was remarkably inferior in smoothness, the dispersion state of the Ni-plated sericite in the coating film was uneven, and the density of the particles over the entire coating film surface was visually noticeable. The unevenness was so remarkable as to be confirmed. When the volume resistivity was measured for the conductivity in the same manner as in Example 1, the volume resistivity was higher than that of Example 1, and was not reproducible in three experiments and was between 0.10 and 1.2 Ω · cm. Fluctuated.
Therefore, it was found that the coating film obtained from the heating resistance paint did not have stable conductivity enough to be used as a sheet heating element.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoto Koshizaki 2-7-12-1215, Azuma, Tsukuba, Ibaraki Prefecture (72) Inventor Masahiro Ishidoya 2-26-6-305, Kajiwara, Kamakura City, Kanagawa Prefecture (72) Inventor Soma Tohru 473 Shimokurata-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Katsuyuki Hayashi 2-7 Muromachi, Aizuwakamatsu-shi, Fukushima Prefecture (72) Inventor Minoru Takano 2-4 Ariakidaihigashi, Ichihara-shi, Chiba Pref. References JP-A-48-101455 (JP, A) JP-A-59-78248 (JP, A) JP-A-55-134229 (JP, A) JP-A-56-53781 (JP, A) 63-110590 (JP, A) JP-A-55-96591 (JP, A) JP-A-57-11489 (JP, A) JP-A-63-133480 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 3/20

Claims (5)

(57) [Claims] 1. A heating resistor paint containing 40 to 150 parts by weight of a flat metal plating powder having an average diameter of 5 to 100 μm and a thickness of 0.01 to 20 μm with respect to 100 parts by weight of a resin solid content. A planar heating element formed by applying a coating for a heating resistor on an insulating substrate provided with electrodes. 2. A base material of the metal plating powder, wherein the base material is sericite,
2. The sheet heating element according to claim 1, wherein the heating element is muscovite, phlogopite, glass or plastic flake. 3. The planar heating element according to claim 1, wherein the plating metal of the metal plating powder is selected from the group consisting of nickel, copper, silver, and a multilayer or alloy thereof. 4. The resin component in the heating resistor paint,
The surface heating element according to claim 1, further comprising a crosslinkable resin. 5. The planar heating element according to claim 1, wherein the insulating substrate is made of plastic, concrete, wood, slate, glass, ceramics, paper, or metal having an insulating coating.