FR2681753A1 - Ultraflat heating element and its method of manufacture - Google Patents

Abstract

Electric heating panel attached onto paving or flooring and capable either of being embedded in a poured synthetic coating or of being adhesively bonded before the laying of the tiles, parquet, carpet, plastic floor covering or bituminous mix. Electrical resistor obtained by carbon fibres braided in a fabric of neutral fibres. This fabric is embedded in a polymer resin for giving an assembly whose thickness varies from 0.5 to 10 mm. The electrical supply is provided by copper strips or braids or conducting resin grout. The power per m<2> is of the order of 200 W in order to obtain a temperature of approximately 25@C. The system can be calculated and produced with higher or lower powers.

Description

EXTRA-FLAT HEATING ELEMENT AND ITS MANUFACTURING PROCESS
The present invention relates to the insertion of electric heating elements during the implementation of coating of added floors.

The advantages of underfloor heating hold the attention of many industrialists and individuals. However, if the traditional system (electric cables or hot water pipes embedded in concrete) was not planned from the start of construction, it is impossible or very expensive to consider later.

The proposed system makes it possible to insert underfloor heating between the concrete support and the final floor covering (6) (tiling, carpet, plastic floor, poured floor) during the partial repair of the premises.

In fact, we will see later that, thanks to its very small thickness, the invention does not modify the altimetry of the soils.

Other systems proposed, in which the heating element made of metal with insulating material on either side, or made of heat transfer tubes, have the drawback of being difficult to handle and of great thickness. Some with reduced thickness are very sensitive to mechanical attacks such as twisting, bending or punching.

CHARACTERISTICS OF THE INVENTION
Electrical resistance obtained by carbon fibers (1) braided in a fabric with neutral fibers (2).

We recommend a glass-carbon fabric of 170 g / m2. Each carbon fiber is made up of 3,000 8 micron wires and has a resistance of 160 Ohms per m.

These fibers are braided in the weft of the glass fabric following a pattern of 7 mm.

The fibers are interrupted at the edge of the fabric. They are interconnected on two sides of the web by a conductive resin poured over a width of 7 cm and a thickness of 0.5 mm (3).

The insulating material binding the assembly is of the polymer resin type (4).

For direct application to the substrate, we use a slow-curing two-component epoxy resin. For the manufacture of transportable elements, we use a two-component polyurethane resin with an elongation coefficient of 100% to obtain good flexibility.

The power supply (5) of the system can be made at different voltages in alternating or direct current.

The desired goal is to obtain a low temperature heating of 250C for better comfort. We use the 48 V voltage in alternating current and according to a maximum intensity of 0.2 Ampere per fiber, all regulated by a timer or thermostat.

Whether the system is implemented directly on site or prefabricated in the form of panels, the following advantages should be noted 1] If for reasons of improper handling at the time of installation
of the glass-carbon fabric a connection with the conductive resin is
defective, electrical continuity is then ensured by the fibers
perpendicular carbon.

2] The system being particularly recommended in underfloor heating, in progress
use, accidents such as punching due to falling objects
heavy, drilling, anchoring ... can cut carbon fibers. In
this case also the electrical continuity is ensured by the fibers forming
bypass.

3] The thickness of the system is 1 mm, which allows it to be inserted under
any floor covering without changing the altimetry.

4] The mechanical resistance of a glass fabric-resin composite is no longer at
to prove. It appears that in the case of fragile, friable or
cracked, the placement of the system helps to solidify the surface
support.

5] Whether the invention is implemented directly on a support or whether
is applied with glue in the case of a prefabricated element, its great flexibility
allows it to match flat or non-flat surfaces.

IMPLEMENTATION ON EXISTING SUPPORT
The surface (concrete, wood, asphalt, metal) will be dry, free of all laitance, rust, impurities by sanding, shot blasting or sandblasting.

We will first apply a resin-based bonding primer
Fluid epoxy to close the porosity of the support. In the case of a metal support, a second layer of epoxy resin 0.3 mm thick will be essential for electrical insulation.

We will then unroll the glass-carbon fabric in the form of a strip, the length and spacing of which will have been previously calculated according to the desired heating power.

The fabric should be laid flat, avoiding folds or puffs.

On the edges of the two long lengths of each strip, we will pour a conductive resin net (of the 260 L type from the SIKA Company), taking care to spread it with a boiling roller to obtain a strip approximately 7 cm wide.

At the ends of these conductive resin bands will also be connected the copper current supply braids.

After polymerization of the conductive resin, we will proceed with the casting of the insulating epoxy resin embedding the fabric. The quantity of resin per m2 will be 0.400 kg. Spread with a sheepskin roller, it will then be carefully tightened with a boiling roller.

The assembly will then be ready to receive a floor covering of the synthetic poured floor type, glued tiling, carpet, parquet, rubber or coated coating.

PREFABRICATION PROCESS
The dimensions of the heating plates will be 1.25 by 1.65 m.

The tools will consist of a polyethylene plate with 5 mm edges forming a bowl.

On the entire surface of the plate, we will lay out, flat, a strip of glass-carbon fabric.

On the edges of the two long lengths of the fabric, a conductive resin net (type 260 L from the SIKA Company) will be cast, spread with a boiling roller in order to obtain strips 7 cm wide.

At the ends of these bands of conductive resin will be connected the stranded copper cables for the current supply.

After polymerization, we will pour a flexible and tinted two-component polyurethane resin. The quantity will be 0.400 kg per m2. It will be well distributed with a sheepskin roller and tightened with a boiling roller.

Before polymerization, a powdering of 0.200 kg / m2 of silica calibrated to 0.3 mm will aim to roughen the surface for good adhesion of the coating adhesives.

Six hours later (at 200C), the assembly will be removed from the mold and turned over to receive an identical resin layer at a rate of 0.200 kg / m2. Silica powder will also be provided on this face.

The assembly will then be ready to be placed by acrylic gluing on the support (concrete, steel, wood ...)
The small differences in level between the areas of floor with heating plates and the areas without plates will be filled by a simple leveling product used under any glued floor covering.

Claims (1)

CLAIMS i] - Heating structure made of a glass-carbon fabric with the following characteristics * Support in woven glass fibers of 170 g / m2. * Carbon fibers each comprising 3,000 yarns 8 microns and braided in the glass fabric in both directions with a 7 mm pitch. 2] - Structure according to claim 1, ncyée in an epoxy resin film slow-curing bi-component, 1 mm thick. 3] - Structure according to claim 1, embedded in prefabrication in a film of flexible two-component polyurethane resin ensuring flexibility of all. 4] - Structure according to one of claims 1 and 3, with roughness of surface (for good bonding with other materials) ensured by the projection of quartz 0.3 mm on the closing resins of the two faces, before polymerization. 5] - Structure according to claim 1, provided electrical continuity by "bridging" the carbon fibers in both directions in the event of accidental fiber cut as well as poor connection of a or more fibers, at the source. 6] - Structure according to one of claims 1, 2 and 3 with ccnnexion between the copper braids for the current supply and the carbon fibers at the end of the strip, ensured by conductive resin type 260 L or similar. 7] - Structure according to one of claims 1 to 6 can be applied on a support without modifying the altimetry by more than 1 mm. 8] - Structure according to one of claims 1 to 7 may constitute an anti-cracking screen in the case of application on substrates tender or fragile. 9] - Structure according to one of claims 1 to 8 representing a new heating method that can be inserted between floor coverings such as tiling, carpet, plastic floor, cculated floor and the support underlying.