DE7440462U - Heatable surface element - Google Patents

Description

föhm

QmbH Dacmitadt

Pat.Dr.Hh / Emm / 3

Heatable surface element

The innovation concerns a heatable surface element, consisting of a plate made of polymethacrylimld foam and a j associated layer of a thermosetting plastic

j in which a flat, openwork electrical resistor

I stood nestled 1st.

; The innovation is shown in the attached figures (1) and (2)

explained in more detail on an advantageous embodiment. The \ figure (l) represents a vertical section through the new one

Surface element.

Figure (2) shows a section parallel to the outer ; area of the surface element at the level of the electrical resistance

(corresponding to level A, B in Figure 1).

; _; '' Polymethacrylimide foam is resistant to high pressure

i strength and a heat resistance of over 180 °

i off. It is therefore ideally suited for the production of

I layered materials, with a layer of this foam

I cured a layer of thermosetting plastic

f will.

I A layer forms the core of the new heatable surface element

I (l) made of plymethacrylimide foam. Your thickness is determined

I according to the function it assumes in the finished element.

I It must be thicker, the greater the desired strength

I properties are and the greater the thermal insulation effect sdn

I have to. If neither high strength nor good thermal insulation

'are required, but above all a lightweight construction can a layer thickness of, for example, 5 mm is sufficient. At high

f - 2 -

7440462 04/10.75

nuh

GmbH Dnrmrtadt - 2 -

Strength and thermal insulation requirements come with layer thicknesses up to about 50mm into consideration. In most cases, a layer thickness of 10 to 30 mm is sufficient.

The foam layer (1) carries on at least one side the layer of thermosetting plastic provided with a sheet-like resistor. During the production of the surface elements is the thermosetting plastic in liquid form or as Prepreg applied and cured at temperatures up to a maximum of 250 °. Suitable thermosetting plastics are unsaturated Polyester resins, epoxy resins or aminoplast resins, epoxy resins and polyester resins are preferred. On the foam layer (l) First a thin layer of the liquid plastic can be applied, the sheet-like resistor (3) placed on top and finally covered with another layer of the liquid plastic. The planar one Resistance (3) can, however, also be swept directly onto the foam layer (1) and then with the liquid plastic or prepreg coated. This connects through the openings (6) of the resistor (3) the foam (l). In any case, the resistor (3) is embedded in a closed plastic layer (2). The plastic layer (2) must be slightly thicker than the sheet-like resistor and is generally 2 to 5 mm thick. If necessary can have one on each side of the foam layer (1) Plastic layer with an embedded sheet-like resistor be upset. On the outside of the heatable surface element can, if desired, be known per se Way decorative outer layers (4) and (5) are applied. Thermosetting plastics, for example, are suitable for this purpose Impregnated decor papers or layers of, for example, color-pigmented thermosetting plastics, optionally also metal foils or sheets. The sheet-like one embedded in the plastic layer (2) Resistor (3) can for example consist of a fabric of resistance wire exist. It is particularly advantageous to use fabrics

-z 214871

7440462 04/10/75

GmbH Darmitadt

Nonwovens or perforated plastic films, which by means of a coating of an electrical resistance material, such as e.g. carbon black or graphite, and a binder such as polytetrafluoroethylene, have been made electrically conductive.

It is generally advantageous if the openings (6) are small and evenly distributed in the planar resistance, e.g. Case 1st. Before embedding in the plastic layer (2), the resistor must be connected to suitable electrical leads (7, 8) be provided. The size of the electrical resistance and thus the heat output that can be achieved at a given voltage depends on the distance (a) between the electrical leads and the width (b) of the area through which current flows. A very Uniform heating is achieved when the sheet-like resistor has a rectangular shape and two opposing ones Sides each with a continuous power supply (7) or (8)

are connected. With a heating power of 20 watts per dm, temperatures of up to 180 ° can be achieved on the surface of the plastic layer (2) or the outer layer (4). The resistor (3) is due to the complete encapsulation in the plastic Not only fully insulated, but also protected against the corrosive effects of atmospheric oxygen.

The new surface elements are suitable for the production of hot plates or cupboards for food and drinks, as decorative space heating, as well as for other purposes, where value is placed on a particularly uniform, maintenance-free and insensitive heat source.

7440462 04/10/75

Claims (4)

Protection claims 1. Heatable surface element, consisting of a plate made of Polymethaoryllmid-Sohaumstoff and an associated one Schioht of a thermosetting plastic, in the one Flähen-shaped, durohbroohener electrical resistance is embedded .. 2. Heatable surface element according to Claim 1, daduroh separated, that the fläohen-like resistor made of oinem fabric, fleece or a perforated plastic roll with a electrically conductive coating. 5. Heatable surface element according to claims 1 and 2, characterized characterized in that the Sohaumstoffsohioht is connected on both sides with a plastic layer, of which in at least one sheet-like electrical resistor is embedded. 4. Heatable surface element according to claims 1 to 5, characterized characterized in that the sheet-like resistance containing The plastic layer is connected to a heat-resistant decorative outer layer. 7440462 04/10/75