GB1604808A

GB1604808A - Manufacture of shaped articles

Info

Publication number: GB1604808A
Application number: GB14561/77A
Authority: GB
Original assignee: Cape Boards and Panels Ltd
Current assignee: Cape Building Products Ltd
Priority date: 1978-04-06
Filing date: 1978-04-06
Publication date: 1981-12-16

Description

(54) MANUFACTURE OF SHAPED ARTICLES (71) We, CAPE BOARDS & PANELS LIMITED, a British Company of, Iver Lane, Cowley, Uxbridge, Middlesex, UB8 2JQ, do 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:- This invention relates to moulding compositions for the manufacture of shaped articles, and is primarily concerned with providing a novel composition from which fire-resistant and other shaped articles may be made. The invention also relates to a method for making the shaped articles and to the shaped articles themselves.

It is well known to manufacture fibrereinforced shaped articles such as boards from various binder materials (e.g. plastics and cementitious binders) reinforced with various fibrous materials. It is, for example, known to reinforce polyester resin binder with glass fibres, and to reinforce Portland cement or calcium silicate with asbestos fibres.

We have described, in our Patent Specifications Nos. 1 404 001 and 1 498 966 nonasbestos moulding compositions in which ecellent properties, as regards both strength and fire-resistance, are achieved when mica and/or vermiculite is/are incorporated in a mouldable mix comprising a water-settable binder, such as calcium silicate, Portland cement, aluminous cement or blast furnace slag cement together with a non-asbestos fibrous reinforcement. The fibrous reinforcement comprises, in the main, organic fibres which do not melt below 140 C, cellulose fibres being particularly suitable.We have ascertained that the presence of mica and/or vermiculite in these products modifies them to the extent that they show better fireresisting properties than compositions not containing mica and/or vermiculite; and that they shrink very little in comparison when subjected to high temperatures.

We have now discovered that the presence of mica and/or vermiculite in other classes of fibre-reinforced cementitious compounds produces compositions from which shaped articles having very advantageous properties may be manufactured.

According to the present invention, a composition suitable for the production of shaped articles comprises a water-settable cementitious binder, fibrous reinforcing material including asbestos fibres and organic fibres, and mica and/or vermiculite.

Suitable cementitious binders include calcium silicate binders (or materials necessary for the production thereof, i.e. lime and silica), Portland cement, aluminous cement, supersulphated cement, and blast furnace slag cement. The asbestos fibres may be of the amosite, chrysotile or crocidolite type, and the organic fibres, which may be natural or synthetic, may include fibres or cellulose, carbon, viscose, polyethylene, polyamides, polyesters, and polypropylene.

Suitably other fibrous reinforcing materials are present, for example inorganic fibres such as glass fibres (suitably alkali-resistant), mineral wool fibres, e.g. rock wool fibres, slag wool fibres and metallic e.g. steel fibres.

The cementitious binder will preferably be present in an amount of 70 to 80%, by weight, based on the total solids content of the composition; the fibrous reinforcing material will preferably be present in an amount of 2 to 12%, on the same basis (the asbestos fibre suitably constituting between 50 and 75 % by weight of the asbestos fibre/organic fibre mixture); the mica and/or vermiculite will preferably be present in an amount of 5 to 20 %, on the same basis; and the additional inorganic fibres, when present, will preferably be present in an amount of 2 to 15%, on the same basis.

The compositions of the present invention may be formed into shape, e.g. into boardshape, using the techniques described in Patent Specifications Nos. 1 404 001 and 1 498 966. Thus, they can be formed into shape on a Magnani machine, a Hatschek machine, a Fourdrinier machine or a simple de-watering press. They can also be formed into shape by other, less conventional methods, for example injection-, extrusionand suction-forming, with or without fluidisation using super-plasticisers or high frequency vibration.

Whatever forming technique is used, the compositions of the invention will normally initally be formed into an aqueous slurry, the organic fibrous materials suitably being hydrapulped and dispersed before the other ingredients are added. The slurry will have its water content adjusted as desired (such may not be necessary when fluidisation techniques are used, since less water is required to form the initial slurry), after which the slurry is formed into shape and the binder caused to set. Whatever technique is used for the setting of the binder will depend upon the nature of the binder.

For example, if the binder is Portland cement, the setting may be by air-curing or by steam heating followed by maturing.

If the binder is a calcium silicate binder, setting may be achieved by an autoclaving technique.

The mica and/or vermiculite used in the compositions of the invention suitably have have an average particle size (flake diameter in the case of mica) of less than 2mm.

Preferably the particle size of the mica and/or vermiculite is such that at least 95 / is of a particle size less than 0 6mum. Particularly suitable grades of mica are muscovite, biotite and phlogopite (e.g. Suzorite-Trade Mark). The mica preferably has a bulk density of less than 5OOKg/m3, most preferably less than 350Kg/m3.

The following Examples are given for the purpose of illustrating the invention, the contents of the various ingredients being specified as parts by weight.

Examples 1-3 The following mixtures of ingredients were formed into boards using a Hatschek or Magnani machine, or a dewatering press, the ingredients first of all having been formed into an aqueous slurry.

Ex. 1 Ex.2 Ex.3 Vermiculite (95 % less than 0.6mum). 10 - Mica 10 15 15 Cellulose 3 3 3 Amosite asbestos 5 5 5 Lime 36 38 5 36 Silica 36 38 5 36 Glass fibre ("Cemfil") (Trade Mark) - 5 Mineral fibre ("Rocksil" trade mark) - 10 The boards produced after curing had good strength and fire-resisting properties, and little shrinkage when exposed to high temperatures.

Example 4 Similar products to those listed above under Examples 1-3 were produced by replacing the lime and silica (i.e. the calcium silicate binder-forming ingredients) with an equal amount of Portland cement; and by replacing the amosite asbestos with an equal amount of chrysotile asbestos.

Reference is directed to divisional application no. 36000/80 (Serial No. 1 604 810).

WHAT WE CLAIM IS: 1. A composition suitable for the production of shaped articles, comprising a water-settable cementitious binder, fibrous reinforcing material including asbestos fibres and organic fibres, and mica and/or vermiculite.

2. A composition as claimed in claim 1 wherein the cementitious binder is a calcium silicate binder (or materials necessary for the production thereof), Portland cement, aluminous cement, supersulphated cement or blast furnace slag cement.

3. A composition as claimed in claims 1 or 2 wherein the asbestos is of the amosite, chrysotile or crocidolite type.

4. A composition as claimed in claim 1, 2 or 3, wherein the organic fibres are cellulose fibres.

5. A composition as claimed in any of claims 1 to 5 wherein the ingredients are present in the following amounts by weight, based on the total solids content of the composition:- cementitious binder 70 to 80%.

fibrous reinforcing material 2 to 12%; mica and/or vermiculite 5 to 20 %.

6. A composition as claimed in any of claims 1 to 5 comprising additionally inorganic fibres other than asbestos fibres.

7. A composition as claimed in claim 6 wherein the additional inorganic fibres are present in an amount of 2 to 15% by weight based in the total solids content of the composition.

8. A composition as claimed in claim 6 or 7 wherein the additional inorganic fibres are glass fibres or metal fibres.

9. A composition as claimed in any of claims 1 to 8 wherein the mica and/or vermiculite has an average particle size of less than 2mm.

10. A composition as claimed in claim 9 wherein at least 95% of the mica and/or vermiculite has a particle size less than 0-6mm.

11. A composition as claimed in any of claims 1 to 10 wherein the mica is muscovite, biotite or phlogopite.

12. A composition suitable for the production of shaped articles, substantially as described in any of the Examples.

13. Shaped articles produced from a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. shape on a Magnani machine, a Hatschek machine, a Fourdrinier machine or a simple de-watering press. They can also be formed into shape by other, less conventional methods, for example injection-, extrusionand suction-forming, with or without fluidisation using super-plasticisers or high frequency vibration. Whatever forming technique is used, the compositions of the invention will normally initally be formed into an aqueous slurry, the organic fibrous materials suitably being hydrapulped and dispersed before the other ingredients are added. The slurry will have its water content adjusted as desired (such may not be necessary when fluidisation techniques are used, since less water is required to form the initial slurry), after which the slurry is formed into shape and the binder caused to set. Whatever technique is used for the setting of the binder will depend upon the nature of the binder. For example, if the binder is Portland cement, the setting may be by air-curing or by steam heating followed by maturing. If the binder is a calcium silicate binder, setting may be achieved by an autoclaving technique. The mica and/or vermiculite used in the compositions of the invention suitably have have an average particle size (flake diameter in the case of mica) of less than 2mm. Preferably the particle size of the mica and/or vermiculite is such that at least 95 / is of a particle size less than 0 6mum. Particularly suitable grades of mica are muscovite, biotite and phlogopite (e.g. Suzorite-Trade Mark). The mica preferably has a bulk density of less than 5OOKg/m3, most preferably less than 350Kg/m3. The following Examples are given for the purpose of illustrating the invention, the contents of the various ingredients being specified as parts by weight. Examples 1-3 The following mixtures of ingredients were formed into boards using a Hatschek or Magnani machine, or a dewatering press, the ingredients first of all having been formed into an aqueous slurry. Ex. 1 Ex.2 Ex.3 Vermiculite (95 % less than 0.6mum). 10 - Mica 10 15 15 Cellulose 3 3 3 Amosite asbestos 5 5 5 Lime 36 38 5 36 Silica 36 38 5 36 Glass fibre ("Cemfil") (Trade Mark) - 5 Mineral fibre ("Rocksil" trade mark) - 10 The boards produced after curing had good strength and fire-resisting properties, and little shrinkage when exposed to high temperatures. Example 4 Similar products to those listed above under Examples 1-3 were produced by replacing the lime and silica (i.e. the calcium silicate binder-forming ingredients) with an equal amount of Portland cement; and by replacing the amosite asbestos with an equal amount of chrysotile asbestos. Reference is directed to divisional application no. 36000/80 (Serial No. 1 604 810). WHAT WE CLAIM IS:

1. A composition suitable for the production of shaped articles, comprising a water-settable cementitious binder, fibrous reinforcing material including asbestos fibres and organic fibres, and mica and/or vermiculite.

fibrous reinforcing material 2 to 12%; mica and/or vermiculite 5 to 20 %.

13. Shaped articles produced from a

composition as claimed in any of claims 1 to 12.

14. Shaped articles as claimed in claim 13, in the form of boards.

15. A method for producing a shaped article comprising forming into shape an aqueous slurry of a composition as claimed in any of claims 1 to 13, removing excess water therefrom and causing or allowing the binder to set.