NZ202063A

NZ202063A - Fibre-reinforced articles containing clay,silica and cement

Info

Publication number: NZ202063A
Application number: NZ20206382A
Authority: NZ
Inventors: R O'brien; J A Cook; P Vermeulen; I W Bird; B G Seach
Original assignee: Hardie & Co Pty Ltd J
Priority date: 1982-10-01
Filing date: 1982-10-01
Publication date: 1985-02-28

Description

New Zealand Paient Spedficaiion for Paient Number £02063 202063 Priority Ostsfs): ...a..,, Corr^lzto Specification Filed: ri—. ^jto.wc< f i t • 174 i i y i ri'• L • • h * A ■•■•»•/ 2 8 FEB 1985 Publication Dste: .. mi p Joirr-."?, No: cc>4-e»v4-/3«; C04- I 00,11 K8 ill PI No: Date: NEW ZEALAND PATENTS ACT, 1953 * * OCT *v22 COMPLETE SPECIFICATION FIBRE-REINFORCED CEMENTITIOUS ARTICLES We JAMES HARDIE & COY. PTY. LIMITED, a company incorporated under the laws of the State of New South Wales, Commonwealth of Australia, of 65 York Street, Sydney, New South Wales, Australia hereby declare the invention for which we pray that a patent may be granted. to us, and the method by which it is to be performed, to be particularly described in and by the following statement:— 202063 This invention relates to asbestos-free, fibre-reinforced, cementitJ.ous articles of the kind . exemplified by eur prior Australian patent application 515151-.

"Articles according to the said prior application have proved satisfactory in production, except for a fraction of the articles having a tendancy to fracture or crack at bend areas; during what may be called secondary formation while they are still green. An example of such articles is provided by ordinary corrugated sheets. They are first formed flat and are secondarily formed to corrugate them.

. Thus, the object of this invention is to overcome the stated disability, simply and inexpensively, not only in relation to doubly formed articles, where the need is greater, but in relation to asbestos-free articles according to the said prior application generally.

Our experiments have shown that the above-stated shortcoming can be overcome by inclusion of a small proportion of clay in the.composition of the articles and preferably also by ensuring that the fibre ingredient includes a proportion of relatively long, chopped fibres.

The clay employed may be any common clay such as that known as Attapulgite, but for preference it is Bentonite. The proportion of it in the mix may be from 2% to 10%, and is preferably about 4%.

All percentages stated herein are by weight.

The fibres may consist entirely of ordinary chopped fibres as supplied by producers (average length usually from 1 mm to 3 mm) but for preference this fibre ingredient

Claims

2 © 9 0 & ~--~J •~*/ ^*4# V».-' includes a small proportion of relatively long fibres whereof the length runs from about 6 mm up to 50 mm, preferably about 10 mm. The proportion of long fibres may be from 0.05% to 0.5% of the fibre mass, with the preferred proportion at about 0.1%. The chopped fibres (whether fibriHated or monofilamentous) are preferably cellulose fibres (diameter from 5 to 100 microns) but could be polypropylene, viscose cotton or the like. The mix may include as much as up to 60% of silica with balance (up to 100%) cement. WHATfcvVE CLAIM IS, THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS

1. An asbestos-free article composed of: (a) from 6% to 12% by weight of fibres whereof at least a proportion of the individual fibres is uniformly or variously fibrillated to such a degree that the mass of said v. fibres, as a whole, has a freeness value of 450 Csfito 600 ^ Csf, •' ... (b) from 2% to 10% by wpight of clay, 0v\«^ VyrV ^ from °% to 60^silica' wlcn \Jjj ~))o (d) cement as balance to 100%/. ' '

2. An article according to claim 1 wherein from 0.05% to Jwv*#ir 0.5%/of the fibres in said mass are long fibres being from 6 mm to 50 mm in length.

3. An article according to claim 1 or claim 2 wherein the said fibres are of cellulose.

4. An article according to any one of the preceding claims wherein said clay is Bentonite.

5. An article according to any one of the preceding claims wherein the proportion of clay is 4.

6. An article according to claim 2 or any one of claims 3 to 5 insofar as it is dependant upon claim 2 wherein the length of said long fibres is 10 mm.

7. An asbestos-free, fibre-reinforced article composed substantially as herein described. By -His/Their authorised Agents, D,B.162Il/oh/RG0 A. J. PARK & SON Pef ©5 'u l! - 4 -