FR2779802A1 - Thermal isolating material in honeycombed flame resistant plastic material - Google Patents

Abstract

The material consists of a honeycombed cellular plastic material, which has a high flame resistant. It has its two outer surfaces covered with a metallic material to a give high conductivity. The cellular plastic material is impregnated with a halogen gas acting as a fire retardant. The metallic surfaces conduct away heat in case of a fire, prevents the arrival of oxygen and conserves, within the isolated interior, the fire retardant gas.

Description

The present invention relates to a plastic thermal insulator

  alveolar and which has good fire resistance.

  Protection against fire of cellular plastic insulators is generally ensured by the addition of a flame retardant; example: based on halogen bodies. When the flame retardant plastic is heated, the halogen

  give off faster than oxygen can get, which stops the fire.

  This solution has the major drawback that the halogen gases which are released are immediately dispersed in the atmosphere and carried away by the

  convective movements of the fire.

  The flame retardant plastic foams used until now

  are directly apparent so that they are subject to ignition.

  However, we know that a fire always starts on an ad hoc basis, the insulating foams being remarkably insulating by their function, it turns out that an ad hoc heating is concentrated in one place at the start and more easily causes the point ignition which then is transmitted to the whole. Flame retardant air bubble films are already known. The disadvantage of these air bubble films is that the polyethylene is found in thick walls, therefore containing a lot of material and that the bubbles are very large, around 8 to 25 millimeters. There is thus a large mass of air for a

  occasional heating, which promotes fire.

  Air bubble films with aluminum film are also known (for example patent 87 08058), but this material has the disadvantage that it must be produced in two batches and is of a particularly high cost price, without counting the difficulties and restrictions mentioned above, large diameter of the air bubbles, therefore large masses of air, significant thickness of the cell walls, therefore large mass of plastic material which can melt and flow in

inflamed droplets.

  The thermal insulator according to the invention overcomes this drawback.

  According to a first characteristic, it indeed comprises a foam of material

  expanded plastic with a very fine cell, preferably less than a millimeter.

  The plastic is fireproof. The very fine cellularization determines particularly thin cell walls, therefore a very low mass of matter. The fact that the plastic is expanded into micro-cells also offers the advantage that the air mass inside the foam is reduced to micro-bubbles with very little oxygen, which does not favor the development of the fire, but on the contrary promotes the concentration of flame retardant gases which

  are released during warm-up.

  This plastic film is extruded directly between two films

  io of aluminum in a single production.

  Aluminum films offer the following advantages, according to this patent: 1) Enclose the plastic material in a waterproof metallic film, which prohibits the arrival of oxygen, but which also prohibits the dispersion of flame retardant gases. In the event of heating, the flame-retardant polyethylene foam sees i5 its concentrated flame retardants between the aluminum films and thus be

  much more efficient for fire development.

  2) Disperse the specific heating over a large area and thus reduce the

  conditions favoring point flammability.

  In the event of overheating, it is noted that the exterior aluminum film distributes the heat by conduction over a large area, thus reducing the risks

  fire and ignition since the temperature is lower.

  3) The aluminum films prohibit the arrival of oxygen allowing the development of the fire and prohibit the escape and dispersion in

  the atmosphere of the flame retardants contained in the material.

  4) The aluminum films protect the thermal insulator against its humidification by the always present water, we know that a maintained insulator

  dry has much better characteristics than a wet insulation.

   ) The aluminum films reinforce the characteristics of mechanical resistance particularly with regard to resistance to crushing, to

traction.

  6) Aluminum films protect the insulation from attack, parasites,

  rodents and other insulation ransackers.

  According to a particular embodiment, the foam is extruded directly

between two aluminum films.

  It is already known to extrude a foam between two plastic films according to a known technique. It is enough to replace the plastic or paper films usually used with aluminum films with a thickness of 8

at 50 microns.

  This causes the expanded plastic to be in contact with aluminum, the skin of the foam plastic concentrates and sticks perfectly

1o on aluminum.

  It is thus possible to extrude the plastic foam at one time

  flame retardant between these two aluminum siding.

  This product can be manufactured in thickness from 1 to 50 millimeters depending on the extruders available, without these dimensions being limits to

claims of this patent.

  Smart manufacturing involves extruding plastic foam

  from 6 to 10 millimeters between two aluminum films of 8 to 12 microns.

  According to a variant, it is also possible to extrude a grooved foam between two aluminum films, which makes it possible to reduce the quantity of materials

and to have a more flexible product.

  In a variant, the present complex can also consist, on a poly-extruder machine, of a succession of metallic films and foam foams.

  expanded flame retardant plastic.

  Another particularly interesting characteristic of this manufacturing method is that it allows the use of expansion gases of the freon type, which is non-combustible by essence. It is known in fact that the expansion of plastics with freon gases is extremely limited because of the risks represented by the release of freon into the atmosphere. We now expand plastics with gases such as butane, propane,

  methane which are particularly flammable.

  In the context of the present invention, the expansion can be done with completely flame retardant freon gases, since these gases cannot escape into

  the atmosphere thanks to the presence of waterproof metallic films.

  Thus, in the event of heating, the interior of the foam does not contain any oxygen, contrary to all the expanded plastics currently existing, the interior of the cells also does not contain any combustible gas, but on the contrary, comprises a gas which by itself, is flame retardant and adds to the flame retardant characteristics of additives

incorporated into the foam.

  The present insulator can be used wherever a thermal insulator is sought which has good insulation characteristics, good fire resistance and good humidity resistance, good flexibility.

  for a particularly economical price.

  In an interesting variant, it is also possible to manufacture this type of insulation on a so-called poly-extruder machine by placing in the center a layer of flame-retardant foam expanded plastic material, covered on each side with an aluminum film and also having on each side of the aluminum film, other aluminum films which are simply laminated

on the previous film.

  The addition of aluminum films without expanded plastic inside makes it possible to form a laminated barrier which has better resistance to heat transmission and a seal against the arrival or

even greater gas outlet.

  This insulator will find some of these jobs in construction, vehicles, means of transport, industry etc ... and everywhere where one seeks to reduce heat transfers with a flexible product resistant to fire,

  humidity, to the reagents of insulation.

Claims (4)

  1 / Insulating complex reducing energy transfers with good fire resistance, characterized in that it consists of one or more layers of flame-retardant micro-cellular plastic material arranged between metallic films.   2 / insulating complex according to claim 1 characterized in that the layer or layers of expanded plastics consist of flame retardant plastics by addition of flame retardants releasing gases flame retardant in the event of heating.   3 / insulating complex according to claim 1 and 2 characterized in that the or 1o the layers of flame retardant plastics are enclosed between metallic films conductive of heat and constituting tight barriers opposing the arrival of oxygen from air as well as the dispersion of the flame retardants incorporated in the cellular material and which are released during the heating of a fire, these waterproof films are opposed to the dispersion of the blowing agents based on freon which are dangerous for the environment, oppose the humidification of the insulation by the surrounding humidity, reinforce the mechanical resistance particularly   crushing, disperse the point heating.   4 / insulating complex according to the preceding claims, characterized in that   that it is manufactured on a polyextruder machine or the traditional supports are replaced by metallic films and the layers of plastic materials   are added with blowing and flame retardants.   SI insulating complex according to the preceding claims, characterized in that   that the cellular plastic material is enclosed between two metallic sheets what prohibits the diffusion of the gases of expansion and that these agents of expansion are of the family of freons which do not comprise any component being able   participate in development or promote fire.   C / insulating complex according to the preceding claims, characterized in that   that it consists of a layer of expanded cellular plastic enclosed between two metallic sheets and that these metallic sheets are themselves enclosed in other laminated metallic sheets to thus form a laminate which distributes and disperses the heat even better and   opposes even better the arrival of air as well as the exit of flame retardants.