Field of the invention

The present invention relates to thermal insulation materials, e.g. for building, ship building, automotive industries, and in particular thermal insulation materials having specific multi-layers with high thermal insulation performance.

Background of the invention

Traditionally, crude thermal insulation materials are composed of up to several inches of non-woven fiberglass fabric to ensure convective and conductive thermal insulation.

As technology evolved, and in particular as the operating temperature of industrial processes increased to improve efficiency, it was found that adding a heat shield against radiative heat transfer would be highly beneficial. Thus, a simple layer of aluminum (Al) foil was then added to the fiberglass fabric, as aluminum is a relatively inexpensive material that can be readily polished to a very high emissivity, ensuring then a large improvement in radiative heat transfer. Aluminum also features an excellent ductility, allowing to get it in relatively thin foil, down to about 6μιη, hence minimizing the cost of material while still maintaining the desired functionality.

Further on, advances in thermal insulation led to compounding several layers of aluminum foil separated by fiberglass fabric, as disclosed in CN101920587.

This document describes a thermal insulation material 1 , as shown schematically in figure 1 , which aims to insulate for instance, warmer parts of industrial installations. This thermal insulation material 1 is divided into two parts which are high and low surface layers 2, 3 and a body 4 respectively, wherein both surface layers 2, 3 are aluminum foils; and the body 4 part consists of fiberglass fabric 5 and a glue solution 6. The fiberglass fabric 5 is bonded to the aluminum foils by the glue solution 6 prepared from an epoxy resin previously treated by a fire retardant and a curing agent.

However, the warmer parts of industrial installation are often in the vicinity of heat sources that are inherently at risk of creating fire conditions. Thus, in case of fire, regardless of the cause, the insulation material used in CN101920587 may fuel the fire by creating flammable gases or fire-lit droplets, or may create toxic smoke.

The aim of the invention is therefore to overcome the drawbacks and meet the expectations listed above.

Summary of the invention

The invention therefore relates to a thermal insulation material, comprising inner and outer layers of reflective material with a reflectivity over than 90%, a non-combustible material located between said inner and outer layers and bonded to said inner and outer layers by a polymeric primary bonding agent containing a load of fire-retardant, characterized in that said polymeric primary bonding agent contains a load of fire-retardant.

The idea of the invention is therefore to provide a chemically inert radiative heat shield with overall mechanical strength and a fire retardant capacity.

The thermal insulation material may advantageously have the following features:

the inner layer comprises vent holes arranged to release in a controlled fashion the pressure created by expansion or partial gasification of the heated polymeric primary bonding agent in case of exposure to excessive heat. The invention advantageously presents a perforated inner layer in order to form vent holes to release in a controlled fashion, the pressure created by expansion or partial gasification of the heated bonding agent in case of exposure to excessive heat, such as fire. Thus this feature prevents the creation of flammable gases, fire-lit droplets or toxic smoke;

the non-combustible material is chosen in the group comprising light weight mesh and fabric made material;

it comprises additional layers of reflective material located between the inner layer and the non-combustible material, and bound with the inner layer and the non-combustible material by the polymeric primary bonding agent; this feature advantageously allows to enhance the thermal insulation performance;

each additional layer comprises vent holes;

each additional layer has a thickness of about 10 μιτι;

the outer layer is coated with an external layer made of a material that become less reflective when exposed to excessive heat to increase radiative losses toward the outside and dissipate excessive heat;

the inner and outer layers are made of aluminum foil; aluminum material advantageously provides radiative heat shielding;

the inner and outer layers have a thickness of about 30 μιτι;

the lightweight mesh or the fabric made of non-combustible material is fiberglass-based; advantageously provides mechanical strength, while being chemically inert, especially non-combustible;

the polymeric primary bonding agent contains primarily Polyethylene; the polymeric primary bonding agent contains Ethyl Vinyl Acetate; Ethyl

Vinyl Acetate (EVA) is advantageously used to increase the adhesion and bonding strength;

the polymeric primary bonding agent contains Ethylene Methyl Acrylate; Ethylene ethyl Acrylate (EMA) is also advantageously used to increase the adhesion and bonding strength;

the inner layer is bonded to a layer of conductively-convectively insulating material, such as fiberglass or other mineral fiber-based « wool », or other specially fire-safe material. Brief presentation of the drawings

The present invention will be better understood and other advantages will become apparent upon reading the following description and the accompanying drawings in which:

- figure 1 illustrates a thermal insulation material of the prior art;

figure 2 illustrates a thermal insulation material according to an embodiment of the present invention ;

figure 3 illustrates a thermal insulation material according to another embodiment of the present invention;

- figure 4 illustrates a thermal insulation material according to an embodiment of the present invention.

Description

In Figure 2, there is illustrated an example of a thermal insulation material indicated by reference numeral 10, which prevents the creation of flammable gases, fire-lit droplets and toxic smoke.

The thermal insulation material 10 comprises inner and outer layers 1 1 , 12 of reflective material. Different kinds of reflective materials can be used with a reflectivity over than 90%. Here the aluminum is chosen because of its high reflectivity, and because of its adapted emissivity which can be improved after a polishing step. In this example, both layers have a thickness from about 30 μιτι. However, it is possible to vary the thickness of both layers 1 1 , 12 independently one another.

The inner layer 1 1 is in contact with a thick primary conductive- convective insulation layer 13, whereas the outer layer 12 is in contact with outside heat sources, indicated by reference HS. The inner layer 1 1 further comprises several through vent holes 14, in the width over its entire surface.

Moreover, in-between the outer and inner layers 1 1 , 12, a lightweight mesh or a fabric made of non-combustible material, indicated by the reference 15, is placed. Here, in the figure 2, the lightweight mesh or the fabric made 15 is fiberglass-based but may be chose among another inert mineral material.

Both layers 1 1 12 and non-combustible material 15 are bonded together by a polymeric primary bonding agent 16 containing a load of fire-retardant material. Here, the polymeric primary bonding agent 16 comprises primarily polyethylene, but can be also chosen among the non limitative list comprising Ethyl vinyl acetate (EVA) and Ethylene methyl acrylate (EMA).

In figure 3, the thermal insulation material 10 comprises first and second additional layers 17, 18 of reflective material located between the inner layer 1 1 and the non-combustible material 15, and bound to the inner layer 1 1 and the non-combustible material 15 by the polymeric primary bonding agent 16. Different kinds of reflective materials can be used as the same manner as for the inner and outer layers 1 1 , 12. The first additional layer 17 is bound to the non-combustible material 1 5 whereas the second additional layer 18 is bound to the first additional layer 17 and to the inner layer 1 1 . Each additional layer 18 is bound by the polymeric primary bonding agent 16 containing a load of fire-retardant material. Note that, in figure 3, the first additional layer 17 has a thickness of about 30 μιτι, the second additional layer 18 of about 10 μιτι and the inner layer of about 10 μιτι and further comprise several through "vent holes" 15 in the width over their entire surface.

In figure 4, the thermal insulation material 10 of the figure 1 is coated by an external layer 19 on the outer layer 12. The coating is generally performed by a material that becomes less reflective when exposed to excessive heat to increase radiative losses toward the outside and dissipate excessive heat. Here, the external layer 19 is coated by carbonization in a thickness of about 5 μιτι. In this example when using carbonization coating, the external layer 19 is transparent and turns to black when exposed to fire. All embodiments of the present invention obviously can be combined with each other to improve the thermal insulation performances while reducing the risk of fire.

It is obvious that the present invention should not be limited to the foregoing description of the embodiments thereof, which may be modified without departing from the scope of the invention.