INSULATING PRODUCT

BACKGROUND OF THE INVENTION

[0001] This invention relates to an insulating product which is suitable for use as a roof insulating material. The scope of the invention is however not limited to this particular application.

[0002] Typical roof insulating materials known to the applicants include a sheet material with one or more silvered or reflective surfaces which reflect heat from the material, and a lofted fibrous and plastics bubble product which limits heat transmission through the product. To the applicants' knowledge these products display only limited fire retardancy characteristics.

[0003] The invention is concerned with a product which is readily manufactured and which offers good thermal insulation and fire resistant qualities.

SUMMARY OF INVENTION

[0004] The invention provides an insulating product which includes a material which is at least partly impregnated with a substance which includes a plurality of encased gaseous voids.

[0005] The material may be of a nature which permits the material to expand to a limited extent under the action of the substance. The material may thus have interstices, voids or cavities which the substance can occupy. For example the material may be porous or fibrous. The material should, itself, be a poor heat conductor i.e. offer good thermal insulation properties. The material should

inherently have a fire retardant characteristic or it should be treated with an appropriate fire retardant so as to exhibit this characteristic. The material, should also be able to bond or key to the substance, a requirement which can be met, for example, by the porous or fibrous nature of the material.

[0006] The weight or density of the material may vary according to requirement. Similarly its thickness may vary according to requirement. Merely by way of non- limiting examples the material may have a density of from 50g/m ² to 200g/m ² and a thickness of 2mm and upwards.

[0007] The material may be provided in sheet form and the substance may extend on one side of the sheet or on both sides. In a variation of the invention use is made of at least two sheets or layers of material and the substance is positioned, at least, between the layers. With this variation the substance preferably also penetrates, at least partly, the layers.

[0008] The substance may be a gaseous synthetic chemical, for example of an expandable or pre-expandable thermoplastics material which may be blended with other materials or desired properties for example a flame retardant modifier and a synthetic binder.

[0009] The insulating product is preferably provided in sheet form but this is a non- limiting shape.

[0010] The invention also extends to a method of forming an insulating product which includes the steps of at least partly impregnating a porous or fibrous material with a liquid, causing a plurality of gaseous voids to be generated within the liquid

and allowing the liquid to set with a plurality of entrapped gaseous voids within or on the material.

[0011] When the voids are generated the volume of the porous fibrous material and the liquid may be increased.

[0012] The voids may be generated in any appropriate way, for example by exposing the liquid to an energy source which raises the temperature of the liquid. The energy source may be a thermal oven, an infrared source or the like. The temperature of the liquid may be raised for a controlled period. Merely by way of example the temperature of the liquid may be raised to a temperature of from 100 ⁰ C to 160 ⁰ C for a period of from 15s to 90s.

[0013] The liquid may be impregnated into the material in any appropriate way and the invention is not limited in this regard. In one form of the invention the material is immersed in a bath of the liquid. In second form of the invention the liquid is applied to one side of the material which acts as a substrate or underlying layer which receives the liquid. In another form of the invention the liquid is positioned in sandwich form between two opposing sheets of the material. This allows the liquid to penetrate each of the sheets.

[0014] The liquid may be impregnated into the material using spray, direct or indirect foam, printing or lick roller baths or similar application techniques.

[0015] Prior to the generation of the voids the material and the liquid may be subjected to a roller or vacuuming process to extract excess liquid and to produce an intermediate product which is of a predetermined thickness before that intermediate product is subjected to the void-generating step.

[0016] The insulating product of the invention can be laminated or printed to meet specific market requirements. A sheet can for example be laminated to an outer surface of the product after its manufacture, or as a final step in the manufacture of the finished product.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention is further described by way of examples with reference to the accompanying drawings Figures 1 to 3 each of which illustrates a respective manner of making an insulating product according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0018] In broad terms the invention is based on the provision of an insulating product which comprises a fibrous material impregnated with a gaseous or void forming synthetic chemical.

[0019] The fibrous material may be a synthetic fibre such as glass, polyester, nylon or polypropylene or a natural fibre such as cotton or coir. The synthetic chemical may be an expandable or pre-expandable thermoplastics material which includes a large number of microspheres with gas-proof shells which contain a liquid hydrocarbon. The chemical is blended with water, a synthetic binder, a filler, a flame retardant and a rot-proofing agent to enhance its end properties. A suitable chemical is that sold under the name Expancel™ by Akzo Nobel of Sweden.

[0020] The fibrous material should be an effective thermal insulator. If the fibrous material is not inherently fire resistant it should be treated to be flame retardant.

Similar considerations apply to the substance which is impregnated into the fibrous material.

[0021] Figure 1 of the accompanying drawings illustrates one way of making an insulating product 10 according to the invention.

[0022] A fibrous layer 14 of any of the indicated materials, for example of polyester, which is loosely structured or air-layed using conventional techniques, and which has a weight of from 80 to 200 g/m ² , acts as a substrate which is passed over a bed, not shown, and a chemical 16 is applied to an upper surface of the substrate.

[0023] As is indicated somewhat symbolically the chemical is produced from a thermoplastic substance 18 which is mixed by means of a blender 20 with a flame retardant 22, a binder 24 and other ingredients.

[0024] The chemical 16 is applied to the substrate in any appropriate way for example by using a spray or a direct or indirect foam applicator. The thickness 28 of the substance, on the substrate, is controlled by means of a skimmer 30 which scrapes excess material from the substrate. Thereafter a second layer 32 of the fibrous material is brought into close contact with an upper surface of the chemical and the two layers of fibrous material with the liquid sandwiched between them are passed through padded rollers 34 or are subjected to a slot vacuuming system (not shown) to remove excess chemical. This step also ensures that the chemical, in the illustrated example, is fully impregnated into the fibrous layers.

[0025] The product then passes to a drying and curing stage 38 where moisture is released from the chemical and expansion and film forming of the product take place. The drying and curing stage can be carried out by direct heating in a hot air over or

by infrared techniques. The temperature in the oven is controlled in the range of from 120 ⁰ C to 160 ⁰ C. The dwell time, i.e. the time for which the product is exposed to the heating process, is subject to a number of variables but typically lies in the range of from 30s to 90s.

[0026] The thermoplastic substance 18 includes small particles 18A of liquid hydrocarbon which are thoroughly dispersed in the chemical 16. When exposed to heat these hydrocarbon particles gasify and expand, forming a large number of entrapped gaseous microspheres or voids 18B. This results in an expansion of the

volume of the chemical which manifests itself in an increase in the thickness of the segment between the two fibrous layers.

[0027] The product 10 which emerges from the oven, in this example, consists of the expanded thermoplastic material which includes a plurality of gaseous voids 18B sandwiched between opposed layers 14 and 32 of fibrous material into or onto which the thermoplastic material is adhered. At least to a limited extent the thickness of each fibrous layer is increased by the reaction of the chemical within the fibrous layer.

[0028] The product 10 can be processed into rolls or cut to size, according to requirement, and is ready for use. Optionally however it is possible to laminate the product onto carriers, not shown, or to print patterns or designs onto the product, using silk screening or other techniques, to meet customer requirements.

[0029] Figure 2 illustrates a process for making an insulating product 10A which bears many similarities to what has been described in connection with Figure 1 and, for this reason, like reference numerals are used to designate like components. Only

the differences between the process of Figure 2 and the process of Figure 1 are described.

[0030] The chemical 16 is directly applied to a fibrous or porous substrate 14 using a spray device 40. The thickness of the chemical on the substrate is controlled using a scraper, not shown, and the product is then subjected to a drying and curing process in an oven 38. The product 10A which emerges from the oven includes a single layer of the substrate fibrous material with the expanded insulating substance 16A set and adhering thereto due to the at least partial impregnation of the fibrous material by the chemical.

[0031] Figure 3 shows a process wherein a substrate 14 of fibrous material is guided by means of a number of rollers 44 through a bath 46 which contains the chemical 16 in liquid form. The material 14 is fully immersed in the chemical and then passes through padded rollers 34 before going to the oven 38. The insulating product 10B emerging from the oven is generally similar to the product 10A shown in Figure 2 although the void-containing substance produced by the chemical 16 is present to a greater extent on an underside of the substrate compared to the Figure 2 case.