JPS6122434B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sheet heating element used for heat retention by providing a heating element such as a metal foil between insulating layers. It is an object of the present invention to provide a planar heating element in which a bent portion with little residual stress can be formed in the heating element by melting and bending a constituent low melting point thermoplastic resin.

Conventionally, in order to provide a terminal part or a connection part on a sheet heating element, a lead wire b is soldered to a heating element a, as shown in FIGS. 1 and 2, or a lead wire b is connected using a crimp terminal C. It was hot. Therefore, the thickness of the connecting portion of the lead wire b becomes thicker than that of the planar heating element d, which is not preferable because the surface becomes uneven. Therefore, it has been considered to bend a part of the planar heating element d to form a terminal part e or a connecting part f, as shown in FIGS. 3 and 4. However, the cross section of the bent terminal part e and the connecting part f is a planar heating element d, which is formed by laminating insulating layers g, g of thermoplastic resin etc. on both outer layers of the heating element a, as shown in FIG. The bent part i is constructed by bending the planar heating element d and gluing the opposing surfaces together using adhesive layers h, h, and the heating element a is sandwiched and restrained between the insulating layers g and g. Therefore, when the heating element a and the insulating layers g are bent, the stress-free state of the heating element a and the insulating layers g are distorted by the bending, and the residual stress remains in the bent part i. Then, when electricity is repeatedly applied to the planar heating element d, the heating element a expands and contracts, and the heating element a at the bent part i where residual stress exists is damaged, and the damaged part becomes disconnected, making it impossible to conduct electricity. This is the result.

The present invention has been made in view of the above matters. The method of bending the planar heating element of the present invention will be explained below with reference to FIGS. 6 and 8 shown as examples. FIGS. 6 to 7 are examples, and A sheet heating element A is obtained by laminating low melting point thermoplastic resin layers 2, 2 having insulating properties such as polyethylene on both outer layers of the heating element 1, and both outer layers of the sheet heating element A are laminated with layers 2, 2 of a low melting point thermoplastic resin having insulating properties such as polyethylene. The planar heating element B is constructed by laminating high melting point resin layers 3, 3 such as polyester having a higher melting point than the resin layers 2, 2.
An adhesive layer 4 is formed by laminating an adhesive or a low melting point thermoplastic resin such as polyethylene on one side of the outermost layer of the planar heating element B. Therefore, the terminal section or connection
A bent part C of the planar heating element B to form a continuous part.
Heat is applied locally so that only the low melting point thermoplastic resin layers 2, 2 are melted. In this case, the high melting point resin layers 3, 3 prevent the low melting point thermoplastic resin layers 2, 2 from flowing out. Then, the planar heating element B is bent with the adhesive layer 4 on the inside, and the opposing adhesive layer 4 is attached. Also, in advance, the planar heating element B
After bending, heat may be applied to melt the low melting point thermoplastic resin layers 2, 2. In any case, by melting the low melting point thermoplastic resin layers 2, 2, the heating element 1 It is sufficient if the bent portion is formed without being restricted by the resin layers 2, 2. If a low melting point thermoplastic resin layer having approximately the same melting temperature as the low melting point thermoplastic resin layer 2 is laminated as the adhesive layer 4, bonding can be performed at the same time as the low melting point thermoplastic resin layers 2 are melted. .

In the present invention, the low melting point thermoplastic resin layers 2, 2 are provided on both outer layers of the heating element 1, but as shown in FIG. If the heat generating element 1 is placed inward, the slack 5 of the heating element 1 will be generated inward and will not be restrained, and the residual stress will be reduced.

As described above, according to the method for folding a planar heating element of the present invention, the bent portion C is formed by providing the low melting point thermoplastic resin layers 2, 2 on the outer layer of the heating element 1, and further providing the high melting point thermoplastic resin layers 2, 2 on the outer layer of the heating element 1. Since the structure is such that the resin layers 3 and 3 are provided, the low melting point thermoplastic resin can be easily melted by heat, and only the low melting point thermoplastic resin layers 2 and 2 are melted to prevent flow in the high melting point resin layers 3 and 3. Since the bent part C of the heating element 1 is a planar heating element B with little residual stress, when electricity is applied to generate heat, it will not be interrupted for a long period of time. This provides a stable planar heating element that will not cause any damage.

[Brief explanation of the drawing]

1 and 5 show a conventional example, FIG. 1 is a diagram showing a terminal part, and FIG. 2 is a diagram showing a connecting part of a sheet heating element. Fig. 3 is a diagram showing a terminal part provided by folding on a planar heating element, Fig. 4 is a diagram showing a terminal part provided by folding on a planar heating element, Fig. 5 is a sectional view showing the folding part; 6 to 8 show examples of the planar heating element of the present invention, FIG. 6 is a cross-sectional view of one example, FIG. 7 is a cross-sectional view of the folded part of the same example, and FIG. 8 is a cross-sectional view of another example. It is a sectional view of a folded part showing an example. 1...Heating element, 2...Low melting point thermoplastic resin layer,
3... High melting point resin layer, 4... Adhesive layer, A... Planar heating element, B... Laminated planar heating element, C... Bending portion. 〓〓〓〓〓

Claims (1)

[Claims] 1 A sheet heating element A is formed by laminating low melting point thermoplastic resin layers 2, 2 on the outer layer of a heating element 1 such as metal foil, and the low melting point thermoplastic resin layer is formed on both outer layers of the sheet heating element A. A sheet heating element B is formed by laminating high melting point resin layers 3, 3 having a higher melting point than those of 2, 2, and then heat is applied so that only the low melting point thermoplastic resin layers 2, 2 melt and flow. high melting point resin layer 3, 3
A surface characterized in that the sheet heating element B is bent while the low melting point thermoplastic resin layers 2, 2 are protected from flowing out, and the heating element 1 is formed without restraining the bending. How to bend a shaped heating element.