JPH0443506A - Electric insulating sheet and electrothemal sheet using electric insulating sheet - Google Patents

Abstract

PURPOSE:To reduce the entering of moisture, to improve the electric insulation, to increase the flexibility of an insulating sheet, to reduce the weight, and to improve the heatproof property, by using a copolymer resin of ethylene and alpha-olefin. CONSTITUTION:A copolymer resin of the ethylene whose density is 0.870 to 0.915 g/cm<2> and the melting point is 110 deg.C or higher, and the alpha-olefin whose carbon number is 3 to 10 is used. The copolymerization is carried out normally at the temperature 30 to 300 deg.C, at the pressure of a normal pressure to 3000 kg/cm<2>, under the presence or nonpresence of solvent, and in the phase of gas solid, liquid solid, or liquid alone. The manufacture of the insulating sheet is not restricted, and a normal process such as an extruding formation can be applied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrically insulating sheet and an electric heating sheet using the same suitable for snow melting and floor heating.

[Conventional technology]

Conventionally, heat-resistant sheets such as polyester are coated with conductive materials, conductive resin is extruded into sheets, glass fiber cloth is impregnated with conductive substances, or conductive fibers are used. When using a heating element made of cloth or paper with copper foil or copper wire attached to the longitudinal end as an electrode as an electric heating sheet, the heating element must be insulated with a thickness of 0.8 mm or more. A sheet was used that was made into a bag by heat-sealing or other methods and then sealed inside the bag.

The insulating sheet is used to electrically insulate the heating element and to prevent moisture from entering from the outside. Therefore, the functions required of an insulating sheet are excellent mechanical strength, low hygroscopicity, and electrical t1! ! It has excellent edge properties, has excellent heat sealability and no moisture intrusion from the sealed part, has the necessary heat and cold resistance, is highly flexible, and is easy to install and transport. This is because the cost is low.

Conventionally, the raw material for insulating sheets is often a flexible sheet made from a resin made by adding an inorganic filler to a copolymer of ethylene and vinyl acetate for the purpose of imparting heat resistance.

In addition, soft vinyl chloride resin, ethylene-vinyl acetate copolymer alone, thermoplastic rubber, and polyester may be used.

[Problem to be solved by the invention]

The copolymer of ethylene and vinyl acetate has a melting temperature of 97°C.
Since there are concerns about heat resistance, an inorganic filler is added to improve heat resistance. In this case, the hygroscopicity becomes relatively large, resulting in a decrease in insulation performance. In addition, the heat-sealability is also likely to be impaired, which increases the possibility of moisture infiltration from the heat-sealed portion.

There is also the problem that as the specific gravity increases, flexibility deteriorates, impairing workability.

In addition, soft vinyl chloride resin has relatively high moisture permeability and has problems with cold resistance. Thermoplastic rubber has problems with heat sealability and cost. Polyester has problems with flexibility and cost.

[Means to solve the problem]

The present invention is characterized by using a copolymer resin of ethylene and an α-olefin having 3 to 10 carbon atoms, which has a density of 0.870 to 0.915 g/cj and a melting temperature of 110°C or higher. The present invention relates to an electrically insulating sheet, an electrically insulating sheet using the same, and an electric heating sheet using the same.

The polymerization reaction is usually carried out at a temperature of 30 to 300°C, under a pressure of normal pressure to 3000 kg/d, in the presence or absence of a solvent, in a gas-solid, liquid-solid, or homogeneous liquid phase.

Density is 0.870-0.915 g/Cll1. Preferably, it is 0.880 to 0.910 g/cd, and the melting temperature is 110°C or higher, preferably 115°C or higher.

Here, the melting temperature is the highest melting peak temperature determined by DSC, and is measured using a Perkin Elmer 7 DSC according to JIS-
Measured based on 7121.

In the present invention, if the density of the ethylene-α-olefin copolymer resin is less than 0.870 g/cj, the heat resistance is poor;
If it exceeds 0.915 g/c111, the resin becomes hard, lacks flexibility, and has poor workability, which is not preferable.

Furthermore, if the melting temperature is less than 110°C, the heat resistance will be poor and it is not preferable for the use of the present invention.

The method for manufacturing the insulating sort of the present invention is not particularly limited, and it can be manufactured by a general processing method such as an extrusion molding method. Further, stabilizers, colorants, etc. may be added as necessary.

〔Example〕

Examples will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the electric heating sheet of the present invention, and FIG. 2 is a plan view showing the external appearance. In Fig. 1, a conductive paint is applied to a polyester sheet as a base layer 1 to form a conductive layer 2, and an electrode 3 is applied to this.
A heating element is used, in which a copper foil is attached as a heating element, an adhesive is applied thereon, and a polyester sheet as a cover layer 5 is laminated as an adhesive layer 4.A lead wire 6 is attached to one end of the electrode of the heating element. (Figure 2).

1III manufactured by extruding a copolymer of ethylene and butene-1 with a density of 0.900 g/cd and a melting temperature of 115°C, with a thickness of 11 mm and a width and length of 4 mm compared to the heating element.
c111 Place a large insulating sheet 7 on the upper and lower surfaces of the heating element, and wrap around the insulating sheet 7 to enclose the heating element.
Heat seal to a width of cm. The surface of the lead wire 6 is coated with a resin that is the same as the insulating sheet 7 and can be thermally bonded.

The lead m6 portion is also heat-sealed between the insulating sheet and the covered portion of the lead wire. The seal portion 8 is shown in FIG.

The ethylene-butene-1 copolymer used here has a moderate mixture of highly crystalline parts and amorphous parts, has good heat resistance even at low rigidity, and has a melting temperature that is lower than that of ethylene and acetic acid within the same rigidity range. 115° which is about 20°C higher than vinyl copolymer.
Since it is C, there is no need to add inorganic substances, and it is flexible, lightweight, strong, and has good workability. It also has no concerns about heat resistance and has excellent heat sealability. Its volume resistivity is about five times that of ethylene-vinyl acetate copolymer filled with inorganic materials, and it has almost no hygroscopicity, so there is no change in insulation properties over time.

It also has excellent wear resistance and stress cranking resistance, making it superior to conventional products in terms of durability.

[Effects of the invention] (+1) By eliminating moisture absorption and improving heat sealability, electrical insulation is improved and the possibility of moisture intrusion is reduced, increasing safety and durability.

(2) By increasing the flexibility of the insulating sheet, reducing its weight, and improving its heat resistance, it improves workability and increases safety and durability.

(3) Durability is improved by improving mechanical strength and stress cracking resistance.

(4) Has excellent cold resistance.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the electric heating sheet, and FIG. 2 is a plan view showing the external appearance. 1 ... Base material layer 2 ... Conductive layer 3 ... Electrode 4 ... Adhesive layer 5 ... Cover layer 6 ... Lead wire 7 ... Insulating sheet 8 ・・・ Heat seal part leather 11 Shame calculation λ1 sword

Claims (2)

[Claims] (1) Use a copolymer resin of ethylene and α-olefin having 3 to 10 carbon atoms, which has a density of 0.870 to 0.915 g/cm^3 and a melting temperature of 110°C or higher. Characteristic electrical insulation sheet. (2) An electric heating sheet using the above-mentioned electric insulating sheet.