JP2022066436A - Film heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film heater which is less likely to contain air bubbles causing poor appearance and breakage without impairing designability of an adherend that is an object to be heated, can be simply stuck to an adherend having an uneven shape, has high moldability and mechanical strength, and is excellent in adhesion to an adherend.

SOLUTION: A film heater has a conductive pattern composed of a conductive wire provided on one surface of a support sheet composed of a transparent thermoplastic resin sheet, in which the other surface of the support sheet has unevenness, and the conductive pattern has a connection terminal part, a lead wire extending from the connection terminal part, and a heater part continued from the lead wire.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a film heater, and more particularly to a film heater provided on a film with a conductive pattern that can be electrically connected to an external power source.

Conventionally, a film-shaped planar heating element having a conductive pattern for heating, which is used by being attached to an adherend to be heated for the purpose of preventing ice / snow adhesion, snow melting, fogging, and heat retention. It has been known.

For example, Patent Document 1 discloses a planar heating element in which a bare nichrome wire processed into an arbitrary shape is arranged inside two multilayer composite films via an adhesive layer made of an insulating material. , It is described that this planar heating element is attached to a heating object with a double-sided adhesive tape, a double-sided adhesive film, or the like.
US Pat. Is disclosed. The semi-cured resin coating layer containing the heat-generating portion is in a semi-cured state (B stage), has flexibility and plasticity, and has an adhesive surface, so that it can be applied to any shape of the adherend. It is described that it can be followed and pasted.

In Patent Document 3, a metal wire resistor formed in a predetermined pattern is provided on the surface or inside of a flexible transparent base material in the form of a circular sheet having a fan-shaped notch having a central angle of 90 degrees or less. A planar heater for a signal lamp, characterized in that it becomes It is described that even if the display window of the signal light has a dome shape, it is easy to make close contact with it.

Japanese Patent Application Laid-Open No. 2003-257597 Japanese Unexamined Patent Publication No. 2006-278138 Japanese Unexamined Patent Publication No. 2017-004918

When affixed to an adherend using a double-sided adhesive tape or a double-sided adhesive film as in the invention disclosed in Patent Document 1, air bubbles are likely to be contained between the adherend and the adherend, and the appearance is impaired and damaged. It is easy to cause such things as.
The invention disclosed in Patent Document 2 needs to use a special resin coating, requires special equipment such as completely curing the semi-curing resin coating layer by a photocuring method, and tends to complicate the construction method.
The invention disclosed in Patent Document 3 is effective when the display window of the signal lamp has a dome shape, but it is difficult to use it in other cases.

INDUSTRIAL APPLICABILITY The present invention does not impair the design of the adherend to be heated, does not easily contain air bubbles that cause poor appearance or damage, and is easy even for an adherend having an uneven shape. It is an object of the present invention to provide a film heater which can be attached to a film, has high formability and mechanical strength, and has excellent adhesiveness to an adherend.

In the present invention, a conductive pattern made of conductive wires is provided on one surface of a support sheet made of a transparent thermoplastic resin sheet, the other surface of the support sheet has irregularities, and the conductive pattern is connected. It is a film heater having a terminal portion, a lead wire extending from the connection terminal portion, and a heater portion continuing from the lead wire.

In the present invention, the conductive pattern may be formed of one continuous conductive wire.
Also. In the present invention, the connection terminal portion may be configured with a pattern in which the conductive wire is bent at a plurality of points, for example, a meander shape in which the conductive wire is bent at a plurality of points and meanders.
In the present invention, an exterior sheet made of a transparent thermoplastic resin sheet different from the support sheet is provided on one surface side of the support sheet so as to cover the conductive pattern, and the exterior sheet is provided with the exterior sheet. It is preferable that a through hole is provided to expose at least a part of the connection terminal portion to the outside.
In the present invention, a metal plate can be further provided on the connection terminal portion.
In the present invention, it is preferable that the conductive wires constituting the conductive pattern are covered with a self-bonding insulating film except for the connection terminal portion.
In the present invention, the adhesive layer can be provided on the other surface of the support sheet having irregularities.

The film heater according to the present invention is a transparent film heater as a whole, and can be attached to various adherends without impairing the design of the adherend to be heated. Further, since the surface of the support sheet to be bonded to the adherend has an uneven surface, air can be easily released when the support sheet is bonded to the adherend, and it becomes difficult to contain air bubbles that cause poor appearance or damage.
By using a thermoplastic resin sheet for the support sheet and the exterior sheet, if any, it can be easily attached to an adherend having an uneven shape, and in-mold transfer is also possible. It is possible.
By continuously forming the conductive pattern with a single conductive wire, manufacturing becomes easy, and by covering the entire surface of the support sheet on which the conductive pattern is formed with an exterior sheet, it becomes possible to protect the conductive pattern. ..

The present invention is a film heater having good moldability, high mechanical strength, and excellent adhesion to an adherend, and can be applied to various applications such as prevention of ice and snow adhesion, snow melting, fogging prevention, and heat retention. Yes, for example, it can be applied to automobile headlights, motorcycle grips and seats, outdoor lights, traffic lights, and the like.

(A) is a plan view schematically showing an example of the film heater of the present invention, and (b) is a sectional view thereof. (A) is a plan view schematically showing an example of an exterior sheet that can be used in the present invention, and (b) is a sectional view thereof. (A) is a plan view schematically showing an example of the film heater of the present invention using an exterior sheet, and (b) is a sectional view thereof.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a plan view schematically showing a film heater according to an embodiment of the present invention. FIG. 1B is a sectional view schematically showing a film heater according to an embodiment of the present invention.
According to FIG. 1, a conductive pattern made of conductive wires is provided on one surface of a support sheet 1 made of a transparent thermoplastic resin sheet, the other surface of the support sheet 1 has irregularities, and the conductive pattern is formed. It has a pair of left and right connection terminal portions 21a and 21b, lead wires 22a and 22b extending from the connection terminal portions 21a and 21b, respectively, and a heater portion 23 continuing from the lead wires 22a and 22b. As in this embodiment, the heater portion may be non-linear as a whole.
In FIG. 1, the conductive pattern is formed by one continuous conductive wire, and the connection terminal portions 21a and 21b are composed of a linear pattern in which the conductive wires extending from the lead portions 22a and 22b are bent at a plurality of points. Has been done.

The support sheet used for the film heater of the present invention is made of a transparent thermoplastic resin sheet. This makes it possible to suitably produce a film heater that is transparent as a whole. The film heater, which is transparent as a whole, can be attached to various adherends without impairing the design of the adherend to be heated.
Further, by using a thermoplastic resin sheet, it can be easily attached to an adherend having an uneven shape, and particularly when the adherend is a resin molded body, vacuum forming or heat pressing is performed. A film heater can be formed on the surface of a resin molded body by a molding method such as molding, laminating molding, in-mold molding, or insert molding.

As the thermoplastic resin sheet, ethylene-based resin, propylene-based resin, polyolefin-based resin, thermoplastic polyester-based resin, polyamide-based resin, polyvinyl chloride, polycarbonate, ABS resin and the like can be used, and two or more of these can be used. It may be something to do. In particular, it is preferable to use a polypropylene-based resin having excellent moldability, mechanical strength, flexibility, and weather resistance.
Inorganic fine powder or organic filler, dispersant, antioxidant, compatibilizer, ultraviolet stabilizer, antiblocking agent, antistatic agent and the like can be appropriately added to the thermoplastic resin sheet.
The thickness of the thermoplastic resin sheet is preferably 0.030 mm to 1.000 mm, more preferably 0.100 mm to 0.700 mm.
The surface of the transparent thermoplastic resin sheet serving as the support sheet, which is opposite to the surface provided with the conductive pattern made of the conductive wire, that is, the surface to be bonded to the adherend has an uneven surface. Since the support sheet has an uneven surface, air can be easily released when the support sheet is attached to the adherend, and it becomes difficult for air bubbles that cause poor appearance or damage to be included between the support sheet and the adherend.
Examples of the method for forming the uneven surface on the thermoplastic resin sheet include embossing. Due to the space and undulating surface due to the unevenness, the actual area (surface area) per unit area of the surface to be bonded to the adherend can be increased, and the adhesion between the adherend and the support sheet can be improved.
The degree of undulating surface due to unevenness can range from a fine size such as a depth of several microns to a very large size such as several tens of millimeters. It is preferably 5 μm to 50 μm, preferably 10 μm to 30 μm.
There are no particular restrictions on the uneven shape, and it may be a geometric shape such as a corrugated shape, a sphere, a circle, an ellipse, a trapezoid, or a cone, as well as a fine satin finish or various pictorial patterns, but it is good for air to escape. It is preferable that the shape includes a waveform.

The conductive pattern can also be formed by printing with a conductive ink such as silver paste or by etching a metal foil such as copper foil. When forming a conductive pattern, forming a circular conductive wire in a predetermined pattern in a cross-sectional view having a certain diameter makes it easy to form a heater portion, a lead portion, and a connection terminal portion as one continuous linear shape. It is preferable in that it can be done.
When the conductive pattern is composed of conductive wires, it is preferable that the conductive wires include at least a metal wire, and more preferably, the metal wires are covered with a self-bonding insulating film. can do. As the metal wire, for example, a metal wire such as copper, iron, gold, copper nickel, nickel chrome, iron nickel chrome can be used, but other materials can also be used as long as they have conductivity. From the viewpoint of electrical resistance, durability, and cost, it is preferable to use copper or a copper alloy in which zinc, lead, tin, silver, aluminum, nickel, berylium, zirconium, etc. are used alone or in combination with copper.

The insulating coating covering the metal wire is an insulating resin coating, and the conductive wire coated with the insulating coating can be a commercially available enamel wire. Specific examples of the insulating resin coating include polyester, polyethylene, polyurethane, polyvinyl chloride, polyamide, polyimide, polyesterimide, polyamideimide, and fluororesin. The insulating coating is typically black, but the insulating coating may be colored in any color according to the color of the adherend to be heated.
The diameter of the conductive wire constituting the conductive pattern is, for example, 0.03 mm to 0.20 mm. It may not be easy to form a thin conductive wire, but it is better to be as thin as possible so as not to impair the design of the adherend to be heated, and the diameter of the conductive wire is preferably 0.05 mm to 0. It is .15 mm. The length of the conductive wire can be set according to the pattern form of the conductive pattern and the like.

The conductive pattern can be typically formed by routing the conductive wire on the support sheet, drawing a predetermined pattern form, and fixing the conductive wire by embedding it at least on the surface of the support sheet.
As a method of embedding the conductive wire in the surface of the support sheet, for example, it is desirable to embed the conductive wire in the surface of the support sheet by utilizing the principle of ultrasonic fusion. When performing ultrasonic fusion, a wiring drawing device capable of melting the surface of a support sheet made of a thermoplastic resin while feeding out the conductive wire and embedding the conductive wire in the surface of the support sheet can be used. With the ultrasonic head provided in such a wiring drawing device, the conductive wire can be embedded in the surface of the support sheet by vibration and pressurization while feeding the conductive wire onto the surface of the support sheet.
By embedding the conductive wire in the surface of the support sheet, the conductive pattern can be positioned on the support sheet, and the displacement of the conductive wire due to an external impact or the like can be suppressed. Further, by embedding the conductive wire in the surface of the support sheet, it is possible to reduce the degree of unevenness on the surface of the support sheet by arranging the conductive wire on the surface of the support sheet.

Next, an embodiment of the conductive pattern of the film heater of the present invention will be described.
Referring to FIG. 1, the conductive pattern 2 includes a pair of left and right connection terminal portions 21a and 21b, lead wires 22a and 22b extending from the connection terminal portions 21a and 21b, respectively, and lead wires 22a and 22b as a whole. The non-linear heater portion 23 is provided as a continuous linear pattern composed of one conductive wire.
By forming the connection terminal portion, the lead wire, and the heater portion with one continuous conductive wire, the manufacturing process can be facilitated and a low-cost film heater can be manufactured.
In FIG. 1, the connection terminal portions 21a and 21b are formed in a meandering shape in which the conductive wires are bent at a plurality of points and meander. In this case, the connection terminal portions 21a and 21b are preferably formed by increasing the number of folds of the folded portion that bends and meanders at a plurality of places within a predetermined flat area so that the fold lines are densely packed. In the case of the embodiment shown in FIG. 1, in the meander shape, a bent portion having a relatively short length and a straight portion having a relatively long length are repeated, and the number of the straight portions is 2 lines / mm or more. It is preferable to make it so that.

Further, if necessary, a conductive piece made of a metal plate can be further provided on the connection terminal portion in order to improve the connection efficiency with the external electrode. As the metal plate, for example, copper, a copper alloy, iron, iron and a nickel alloy, or the like can be used.
When the conductive wire is covered with an insulating coating, the insulating coating covering the conductive wire at the connection terminal portion is removed to expose the internal metal wire. As a method of exposing, it is possible to cut with a milling device or the like, but it is also possible to melt and remove the insulating film by the heat when soldering to a metal plate or an external electrode.

The heater portion 23 is formed by being routed from lead wires 22a and 22b extending from a pair of left and right connection terminal portions 21a and 21b, respectively. In FIG. 1, the heater portion 23 is a bent portion having a relatively short length. And a relatively long straight line part are repeated, and it is a non-linear linear pattern as a whole, which bends and meanders at a plurality of places. The pattern of the heater portion can be any pattern in consideration of the shape of the adherend, the heating area, and the heating efficiency, and may be a repeating curved shape that does not include a straight portion or a spiral shape.
In FIG. 1, the conductive pattern is composed of a pair of left and right connection terminal portions 21a and 21b and a pair of left and right lead portions 22a and 22b centered on the heater portion 23, and a starting point is an end portion of one of the connection terminal portions 21a by a conductive wire. A meander-shaped connection portion 21a is formed, a lead wire 22a is extended from the other end of the connection terminal portion 21a, and a heater portion 23 is formed by a conductive wire drawn from the lead wire 22a. The other lead wire 22b is extended from the portion 23, and one continuous linear heater portion 23, the lead portion 22, and the connection terminal portion 21 are formed by one conductive wire extending to the other connection terminal portion 21b. Has been done.

In another embodiment of the present invention, an exterior sheet made of another transparent thermoplastic resin sheet that covers the conductive pattern is provided on one surface of the support sheet provided with the conductive pattern, and the exterior sheet is connected to the exterior sheet. It can be a film heater provided with a through hole that exposes at least a part of the terminal portion to the outside.

FIG. 2A is a plan view schematically showing an example of an exterior sheet that can be used in the present invention. FIG. 2B is a cross-sectional view schematically showing an example of an exterior sheet that can be used in the present invention.
In FIG. 2, the exterior sheet 3 having substantially the same shape as the support sheet is provided with a through hole 31 that exposes at least a part of the connection terminal portion of the film heater to the outside.

As the exterior sheet, the same thermoplastic resin sheet as the support sheet can be used, and the exterior sheet can be bonded by heat-treating and / or pressing one surface of the support sheet on which the conductive pattern is formed. can. If necessary, an adhesive layer, an adhesive layer, a heat seal layer, or the like may be interposed between the support sheet and the exterior sheet for bonding. The exterior sheet exposes at least a part of the connection terminal portion to the outside. A through hole is provided. A cutting means such as punching with a die or a laser device can be used to form a through hole in the exterior sheet for exposing the connection terminal portion. Specifically, a biku blade, a cutting blade, a laser cutter, or A milling device or the like can be used.

FIG. 3A is a plan view schematically showing an example of the film heater of the present invention using the exterior sheet. FIG. 3B is a cross-sectional view schematically showing an example of the film heater of the present invention using an exterior sheet.
As can be seen from the embodiment shown in FIG. 3, the entire surface of one surface of the support sheet 1 on which the conductive pattern is formed is covered with the exterior sheet 3 except for the through hole 31, whereby the heat is transparent as a whole. Even in a configuration in which a conductive pattern made of conductive wires is sandwiched between a support sheet 1 made of a plastic resin sheet and an exterior sheet 3, the connection terminal portion 21 can be reliably electrically connected to an external power source. .. Further, it becomes possible to protect the heater portion and the lead portion formed on one surface of the support sheet by covering them with the exterior sheet.
If necessary, an antifouling layer, an anti-fog layer, an anti-fog layer, a hard coat layer, or the like may be formed on the surface of the exterior sheet.

In the present invention, if necessary, the adhesive layer may be provided on the other uneven surface of the support sheet. By using the adhesive layer, it can be easily attached to the adherend. As the adhesive layer, for example, acrylic, urethane, epoxy, rubber, polyester, cellulose, emulsion and other adhesives can be used. Further, if necessary, a filler, a tackifier, a curing agent and the like can be appropriately used as an additive for improving the characteristics of the pressure-sensitive adhesive.
The thickness of the adhesive layer is not particularly limited as long as the adhesive strength can be obtained, and is usually 20 μm to 200 μm, preferably about 25 μm to 75 μm. When forming the adhesive layer, the adhesive can be formed by using a coating method such as gravure coating, gravure reverse coating, comma coating, knife coating, and die coating.

(Example 1)
Prepare a thermoplastic resin sheet (polyca sheet DPI-AO thickness 0.075 mm manufactured by Mitsubishi Resin Co., Ltd.) as a support sheet, and use a metal plate with a flat surface and a metal plate with an embossed mold on the surface to form a thermoplastic resin. The sheet was sandwiched and heat-pressed by a vacuum laminating machine (MVLP-500 manufactured by Meiki Seisakusho, temperature 180 ° C., pressure 0.5 MPa) to perform embossing, and an uneven surface was formed on one side of the support sheet. The uneven surface was a continuous pattern with a waveform having a depth of about 20 μm.
Conductive wire (ELEKTRISOLA self-bonding coating lead wire AB15 φ0.10 mm) on a flat surface of the support sheet, using a wiring drawing device (Ruhlamat WCE150, setting condition: USP1200, speed40%) equipped with an ultrasonic head. It was embedded to form a conductive pattern as shown in FIG.
The conductive pattern has a lead portion length (the length of the straight portion from the terminal portion to the first folded position) of 130 mm, and the heater portion has a straight portion of 90 mm, a folded portion (pitch) of 10 mm, and the number of folded parts (straight portion). The number of lines was 8 times, and the connection terminal portion was set to a straight portion of 17 mm, a folded portion (pitch) of 0.3 mm, and the number of folded portions (the number of lines of the straight portion) of 12 times. Finally, a film heater was produced by cutting into a length of 170 mm and a width of 120 mm.

(Example 2)
A thermoplastic resin sheet (polycarbonate sheet DPI-AO thickness 0.075 mm manufactured by Mitsubishi Plastics Co., Ltd.) to be an exterior sheet was prepared, and a through hole of 10 mm × 10 mm was formed at a corresponding position of the connection terminal portion. An exterior sheet is attached to the surface of the support sheet to which the conductive pattern of Example 1 is wired, and heat-pressed by a vacuum laminating machine (MVLP-500 manufactured by Meiki Co., Ltd., temperature 180 ° C., pressure 0.5 MPa) on the support sheet. It was sufficiently adhered to. Finally, a film heater was produced by cutting into a length of 170 mm and a width of 120 mm.

1 Support sheet 2 Conductive patterns 21a, 21b Connection terminal parts 22a, 22b Lead part 23 Heater part 3 Exterior sheet 31 Through hole

Claims (7)

A conductive pattern made of conductive wires is provided on one surface of the support sheet made of a transparent thermoplastic resin sheet, the other surface of the support sheet has irregularities, and the conductive pattern is formed on the connection terminal portion and the connection terminal portion. A film heater having a lead wire extending from the connection terminal portion and a heater portion continuing from the lead wire. The film heater according to claim 1, wherein the conductive pattern is formed of one continuous conductive wire. The film heater according to claim 1 or 2, wherein the connection terminal portion is composed of a pattern in which the conductive wire extending from the lead portion is bent at a plurality of points. An exterior sheet made of a transparent thermoplastic resin sheet different from the support sheet is provided on one surface side of the support sheet so as to cover the conductive pattern, and the exterior sheet is provided with the connection terminal. The film heater according to any one of claims 1 to 3, which is provided with a through hole for exposing at least a part of the portion to the outside. The film heater according to any one of claims 1 to 4, wherein a metal plate is further provided on the connection terminal portion. The film heater according to any one of claims 1 to 5, wherein the conductive wire constituting the conductive pattern is covered with a self-bonding insulating film except for the connection terminal portion. The film heater according to any one of claims 1 to 6, wherein an adhesive layer is provided on the other surface of the support sheet.

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