AU658206B2 - Insulating material - Google Patents

Description

AUSTRALIA

Patents Act 658206 COMPLETE SPECIFICATION

(ORIGINAL)

Class Application Number: Lodged: Int, Class Complete Specification Lodged: Accepted: Published: Priority: Related Art: 99 9. 9* 9. 9 9 *999 9* APPLICANT'S REF.: CARBORUNDUM RESISTANT MATERIALS LTD.

Name(s) of Applicant(s): Address(es) of Applicant(s): Actual Inventor(s): Address for Service is: PHILLIPS, ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367. Collins Street Melbourne, Australia, 3000 Complete Specification for the invention entitled: INSULATING MATERIAL The following statement is a full description of this invention, including the best method of performing it known to applicant(s): P 19/11/77 INSULATING MATERIAL This invention relates to an insulating product manufactured from fibrous material especially man mude mineral fibres.

Fibrous insulating materials have been used for many years for both domestic and industrial applications and are usually produced in the form of sheets, blankets or batts.

Popular fibrous insulating materials include fibreglass, ceramic fibre and in the past asbestos.

Direct handling of some materials comprised of mineral fibres can lead to user discomfort. For example, with fibreglass handling, it is normally recommended that direct skin contact be avoided as it may lead to skin irritation especially in some individuals. For this reason protective gloves and other protective clothing are usually required when tne product is being installed. Dust and particle emmission from the mineral fibre sheet or batt may also lead to user discomfort especially when installation is effected in small enclosed spaces.

To reduce the emission of particles from these fibrous insulating materials, various different proposals have been suggested. Proposals have in the past been made to coat or spray the insulating material with various different materials and in this manner, bind the various particles together so that they will not readily be dislodged .,,ring the movement of the material, such as when handling.

Adhesives, binders, lubricants and other similar coatings have all been proposed and trialled with differina degrees of success.

Examples of adhesives that have been proposed include starch, latex and formaldehyde based resins such as urea formaldehyde. However, products treated in this manner have not been found to be satisfactory. To act as a suitable dust or particle suppressant, the adhesive or oil needs to be present in such quantity that the total weight of the insulating material is significantly increased. Furthermore, the handling characteristics of the product become less WC 2 suitable, especially when adhesives are used as the final product is less flexible and thus less suitable in some applications.

It is an object of the present invention to provide a fibrous insulating material treated in such manner that it substantially reduces dust particle emission during handling and installation without significantly increasing the mass of the product and without substantially retarding product flexibility.

The present invention overcomes the deficiencies of the prior art by encapsulation. In particular, in accordance with the present invention there is provided an insulating material comprising:an insulating core material which comprises fibreglass, ceramic fibres, mineral wool, rockwool or a combination of two or more of such materials; and an external layer encapsulating said core comprised of a cellulose/polymeric fibre blend; wherein the flexibility of said external layer is substantially the same or greater than the flexibility of said insulating core material.

Preferably, in the encapsulating layer, the cellulose fibre is comprised of viscose. Viscose is prepared by treating cellulose material with caustic soda and carbon bisulphide. Various different polymeric fibres are suitable for use in the fibre blend forming the encapsulating layer. Preferably, however, a polyamide fibre or polyester fibre is utilized. Polyester fibre is the most preferred.

.The composition of the cellulose/polymeric fibre blend is not critically important. However, it has been found that the material has better handling and performance characteristics if the blend comprises at least 10% of either of the fibre types. Accordingly, polymeric fibre is preferably present in a quantity of to 90% by weight with the cellulose fibre making up the difference and thus being present in a quantity of between 90 to 10% by weight. It should be clear, however, that the cellulose fibres and polymeric fibres need not be the same material throughout. For example, the polymeric fibre used in the external layer material can be a mixture of a number of different polymeric fibres. Further, it is not essential that the polymeric and cellulose fibres are the only materials in the fibre blend. Additional fibres may be added as may other compounds such as binders, flame retardents, etc.

In the most preferred embodiment of the invention, the encapsulating layer is made from a polyester viscose fibre blend which comprises between 20 to polyester fibre and 70 to 80% viscose fibre. These percentages are by reference to total fibre weight rather than the weight of the layer which may comprise other materials.

-4- Typically, the cellulose polymeric fibre blend is formed into a sheet using a compatible binder. These binders are well known in the art. Preferably, in the case of a polyester/viscose fibre blend, either an SBR latex binder or an acrylic binder is used.

The encapsulating layer may also optionally be coated with a thin layer of a thermoplastic material such as low density polyethylene.

The core insulating material that may be used in accordance with this invention is a synthetic mineral fibre. The materials contemplated are fibreglass, ceramic fibres, mineral wool or rockwool or a combination thereof. The invention has particular applicability when used in connection with ceramic fibres. The core material may be rigid, semi-rigid or flexible. Ceramic fibre insulating materials can be formed in any of these types. This invention has particular suitability when the core material is semi-rigid or flexible. Unlike fibreglass (for example, that used in domestic insulating batts), silica/alumina ceramic fibre can be used to form light weight flexible blankets and this material is ideally suited for use in the present invention.

A typical chemical analysis of a known silica/alumina insulating blanket is "as follows: c. Chemical Analysis Al203 47.9% SiO 2 51.7% 3 0.04% TiO 2 0.002% MgO 0.01% CaO 0.02% Na203 0.1% Trace Inorganics 0.2% Leachable Chlorides <10 ppm Alternative ceramic fibre insulating blankets comprise zirconia- usually in quantities up to about 10 to Such insulating blankets are flexible and after manufacture are often stored and transported in rolls.

Encapsulation of the core material may be effected by sealing the encapsulating layer around the core either chemically, with an adhesive) thermally or mechanically by stitching). In the preferred embodiment where the encapsulating layer is coated with polymeric material such as low density polyethylene, the edges of the encapsulating layer may be sealed together by the simple expedient of heat fusing the edges together under pressure.

The thickness of the encapsulating material is not narrowly critical. In most applications, a thickness of 25 between 0.1 to 0.2 mm provides sufficient strength and flexibility if the cellulose and polymeric fibres are present in the preferred amounts.

The structure and composition of the insulating substrate of the present invention and the advantages over the prior art are further explained hereinafter by reference to a preferred embodiment which is described by reference to the accompanying drawings in which:- Figure 1 is a perspective view of an insulating substrate made in accordance with the present invention which illustrates an internal view in cut away corner A.

Figure 2 is a cross-sectional view of an insulating substrate made in accordance with the invention which illustrates one end sealing arrangement; and Figure 3 is a WC 5 cross-sectional view of an insulating substrate made in accordance with the invention illustrating an alternative end sealing arrangement.

With reference to Figure 1, there is shown an insulating substrate 1 formed from a core material 6 which is encapsulated by an outer layer 2. Encapsulating layer 2 is sealed at ends 3 and 4 and along join line It can be seen the manner in which the core material 6 is encapsulated by reference to cut away corner A.

Encapsulating layer 2 is made from a viscose/polyester fibre blend wherein the ratio of viscose fibre to polyester fibre is preferably in the order of 3 to 1.

The viscose and polyester fibres are bound by an acrylic binder and the thickness of the encapsulating layer is preferably between 0.1 to 0.2 mm.

The core material 6 is manufactured from a ceramic fibre mix primarily formed from Al 203 and SiO 2 The core may be of any desirable thickness but preferably it is in the order of 5 to 75 mm in thickness. A suitable flexible :.120 core material is manufactured by the applicant and sold under the trade mark FIBERFRAX DURABLANKET.

Encapsulating layer 2 is coated with low density 2 polyethylene preferably in a quantity of 10 g/m The composite product is formed by wrapping and sealing 5. the encapsulating layer 2 about core material 6. Preferably, the encapsulating layer 2 is first formed into a tube of the appropriate width and the core material 6 is fed into the I' said tube. When a desired length has been formed, S* overhanging portions of encapsulating material are fused together at the respective ends. Fusing conditions when low density polyethylene is used as the layer coating are conventionally 2 kg/cm 2 at about 130 0 C applied for about to 12 seconds. Such an end sealing configuration is clearly illustrated in Figure 3. An alternative end sealing configuration is illustrated in Figure 2 wherein it can be seen that end section 7 is folded around to the underside 8 of the layer where it is bonded to base layer 9.

It has been ascertained by the applicants that the WC 6 composite product, the subject of this invention, has significantly reduced particle or fibre emission even when vigorously handled. The encapsulating layer is such that it freely bends and moves to the form of the core material making it easy to store, transport and use.

It is to be understood that various alterations, modifications and/or additions may be introduced into the composition of the various parts previously described of the preferred construction of the composite product without departing from the spirit or ambit of the invention as defined in the following claims.

WC 7

Claims (17)

1. An insulating material comprising:- an insulating core material which comprises fibreglass, ceramic fibres; mineral wool, rockwool or a combination of two or more of such materials; and an external layer encapsulating said core comprised of a cellulose/polymeric fibre blend; wherein the flexibility of said external layer is substantially the same or greater than the flexibility of said insulating core material.

2. An insulating material according to claim 1 wherein said fibre blend of the external layer comprises at least 10% of either of the fibre types.

3. An insulating material according to claim 2 wherein said fibre blend of the external layer comprises between 10 to 90% polymeric fibre.

4. An insulating material according to claim 2 wherein said fibre blend of the external layer comprises between 10 to 90% cellulose fibre. An insulating material according to any one of the previous claims wherein Sthe cellulose fibre used in the external layer material comprises viscose.

6. An insulating material according to any one of the previous claims wherein the polymeric fibre used in the external layer material comprises polyamide fibre. S 20 7. An insulating material according to any one of the previous claims wherein the polymeric fibre used in the external layer material comprises polyester fibre.

8. An insulating material according to claim 7 wherein said polyester fibre is made from polyethylene terepthalate (PET).

9. An insulating material according to any one of the previous claims wherein the external layer is made from a polyester/viscose fibre blend comprising from between 20 to 30% polyester fibre and 70 to 80% viscose fibre.

10. An insulating material according to any one of the previous claims wherein oo.: the fibres of the external layer are formed into a sheet using a compatible binder.

11. An insulating material according to claim 10 wherein the external layer encapsulating the core is a viscose/polyester fibre blend and is formed into a sheet using an SBR latex binder.

12. An insulating material according to claim 10 wherein the external layer encapsulating the core is a viscose/polyester fibre blend and is formed into a sheet using an acrylic binder.

13. An insulating material according to any one of the previous claims wherein the external layer is coated with a thin layer of a thermoplastic material.

14. An insulating material according to claim 13 wherein the external layer is coated with low density polyethylene in a quantity of about 10 g/m 2 An insulating material as claimed in claim 14 wherein said insulating core material is formed substantially exclusively from a silica/alumina ceramic fibre blend.

16. An insulating material according to any one of the previous claims wherein said insulating core material is either rigid or semi-rigid.

17. An insulating material according to any one of the previous claims wherein said core material is flexible and the encapsulated insulation material is adapted to be formed into a roll.

18. An insulating material according to any one of the previous claims wherein the thickness of the said external layer is between 0.1 to 0.2 mm.

19. An insulating material according to any one of the previous claims wherein the thickness of the core material is between 5 to 75 mm. An insulating material substantially as hereinbefore described with particular reference to what is shown in figures 1 and 3.

21. An insulating material substantially as hereinbefore described with particular reference to what is shown in Figure 2. DATED: 6 January, 1994 20 PHILLIPS ORMONDE FITZPATRICK Attorneys for: CARBORUNDUM RESISTANT MATERIALS LTD. 2 1091W 3 3 ABSTRACT An insulating material comprising:- an insulating core material which is comprised at least in part of fibrous material having thermal insulating properties; and an external layer encapsulating said core comprised of a cellulose/polymeric fibre blend; wherein the flexibility of said external layer is substantially the same as or greater than the flexibility of said insulating core material. 806:0, 0 off *0 .o0. 004 o* 0 9* 8 06 66* •o b* go ftf ft fto