GB1597828A

GB1597828A - Building components

Info

Publication number: GB1597828A
Application number: GB1147977A
Authority: GB
Original assignee: THAMES PLYWOOD MFRS Ltd
Current assignee: THAMES PLYWOOD MFRS Ltd
Priority date: 1978-03-08
Filing date: 1978-03-08
Publication date: 1981-09-09

Description

(54) BUILDING COMPONENTS (71) We, THAMES PLYWOOD MANUFACTURERS LIMITED, a British Company, of 183 Harts Lane, Barking, Essex, IGII 8NB, 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 the production of building components, in particular building panels such as fire doors, and panels of the kind known as plaster-board, using gypsum plaster.

The usual way of fabricating such components is to mix gypsum with water, and, if desired, various other additives, to form a wet mix of a generally slurry-like consistency which is then cast in a mould.

The water gypsum weight ratio in such mixes is generally as high as from 50 to 60 parts of water per 100 parts of gypsum (generally referred to as from 50 to 60 gauge), although the stoichiometric quantity of water required in order to ensure that all the gypsum absorbs sufficient water is much lower (about 18 parts by weight).

Because excess water is used, such components tend to require long periods to dry out before they can be handled, and in addition wet mixing gives rise to problems when it is desired to incorporate reinforcing fibres such as glass fibres into the mix. Such fibres tend to agglomerate when added to a slurry, and this makes them less effective as a reinforcing medium.

According to the invention there is provided a process for producing building component, for example, a door or a wall panel, which comprises mixing a filler having the capacity to absorb water whilst remaining dry (i.e. in a non-slurry or powder form) with an amount of water insufficient to convert the filler into a slurry or nonpowder form, combining gypsum with the mixture, and mixing until the composition is substantially uniform, filling a mould with the uniform composition, and compressing the composition in the mould, thereby to expel the water from the filler and bring the water into intimate contact with the gypsum, thereby to cause the gypsum to set.

In a preferred embodiment of the invention, a fibrous reinforcing material is incorporated into the mixture. The mixing is then preferably carried out by tumbling, for example using a twin ribbon blender at least from the time at which the fibres are added, since this gives rise to less of the agglomeration phenomenon mentioned above.

Glass fibres are particularly preferred as the reinforcing material, since these retain their strength when the resulting building component is exposed to extreme heat.

Other, cheaper materials may alternatively be used, such as fibres of a synthetic polymer or natural fibres such as coir, but in general these will not be suitable for use in, for example, fire doors, as they will burn off at relatively low temperatures. The fibres preferably have an average length of from +" to 1", and are preferably used in an amount of from 1 to 5% by weight based on the total weight of the composition.

It is desirable that the filler should be capable of absorbing from an amount equal to its own weight to an amount equal to four times its own weight of water, whilst remaining "dry". It should preferably absorb at least twice its own weight of water. Preferred fillers are perlite kieselguhr and vermiculite, since these absorb large quantities of water. The amount of water to be added has been found to be generally about 40 parts by weight per 100 parts by weight of gypsum.

The amount of filler which may be used will depend on the water absorbency of the filler, and the desired water content of the product. Hence, if a filler is used which will absorb up to 4 times its own weight of water before becoming wet, and it is desired to make a product containing 40 parts by weight of water per 100 parts of gypsum, at least 10 parts by weight of filler per 100 parts of gypsum should be used. The density of the building component, when dry, is usually from 500 to 1000 kg/m3.

A wetting agent may be added to the mix preferably in amounts of from 0.3 to 1.0% by weight of the water content in order to expedite the transfer of the water to the gypsum. Conventional plasticisers, such as polyvinyl acetate may also be added. These are usually added as emulsions in amounts of from 2 to 10 parts (solids) by weight per 100 parts of binder.

The preferred method of mixing of the ingredients is first to tumble the filler whilst gradually adding the water, and the plasticiser and wetting agent, if used, and then to add the gypsum and the reinforcing fibre, if used.

The pressure under which the composition should be compressed should generally be at least 2, and preferably from 2 to 7 kg cm-2.

Building components according to the invention may be used, for example as fire doors, wall panels or marine bulkheads. In addition, by using an appropriately shaped mould certain slightly more complex shapes can be produced, for example corners for column casings.

The invention is illustrated by the following Examples.

EXAMPLE 1 A building panel in accordance with the invention was prepared suitable for a door capable of passing the so-called "one hour" test (B.S. 476 Part 8, 1972). 8.6 kg of water were mixed with 3 Kg of an aqueous P.V.A.

emulsion (solids content 45%) and 112 g of an anionic detergent (Teepol-Registered Trade Mark). The resultant liquid was sprayed onto 5 kg of dry perlite (E.P.U.

100/35) whilst the perlite was tumbled in a "BMW-Rapid" mixer. 200 g of SN glass fibres, 10 kg of a-plaster and 10 kg of p- plaster were then added, and tumbling was continued until the mixture was substantially uniform. The uniform mixture was turned into a mould of dimensions 74 x26t to a thickness of approximately 4+".

Pressure was applied (4 kg cm-2) and the 4g layer compressed to approximately 1+".

The resulting door core had a density when dry of between 600 and 700 kg/m3.

EXAMPLE II In the same manner as in Example I, but omitting the P.V.A. emulsion, the following ingredients were combined: 4 Kg plaster 1 Kg Perlite (EPU/35) 2.2 Kg water 20 g anionic detergent (Teepol) 200 g 1 glass fibres.

The resulting composition was compressed in a mould at a pressure of 4 Kg cm. The resulting panel was tough and suitable for use as a ships bulkhead, and of passing the "Standard Fire Test" described in Regulation 3, of Chapter II-2 of "Safety of Life at Sea" (1974). The panel had good screw-holding properties and could be surfaced with a decorative material such as a wood veneer or a plastics laminate (e.g. a melamine, P.V.C. or polyester laminate).

Using this composition, panels were made having thicknesses of from 10 mm to 30 mm.

EXAMPLE III In the same manner as in Example II, but omitting the anionic detergent, the following ingredients were combined: 4 Kg p-plaster 1 Kg Perlite 2.4 Kg water 80 g iN glass fibres.

The resulting composition was compressed in a mould at a pressure of4 Kg cm. The resulting dry component was light, and suitable for use as a column casing in a position where impacts are likely to be slight or non-existent. Using the composition, panels were made having thicknesses of from 10 to 30 mm.

WHAT WE CLAIM IS: 1. A process for producing a building component, which process comprises mixing a filler having the capacity to absorb water whilst remaining dry (as hereinbefore defined) with an amount of water insufficient to convert the filler into a nonpowder or slurry forms, combining gypsum with the mixture, and mixing until the composition is substantially uniform, filling a mould with the composition, and compressing the composition in the mould thereby to expel the water from the filler and bring the water into intimate contact with the gypsum thereby to cause the gypsum to set.

2. A process as claimed in Claim 1 wherein the filler is one which will absorb at least twice its weight of water whilst remaining dry.

3. A process as claimed in Claim 1 or Claim 2, wherein the filler is perlite, kieselghur and vermiculite.

4. A process as claimed in any one of Claims 1 to 3, wherein the amount of water used is approximately 40 parts by weight per 100 parts by weight of the binder.

5. A process as claimed in any one of Claims 1 to 4, wherein a wetting agent is incorporated into the composition, to expedite the transfer of the water to the binder.

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

Claims

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

A wetting agent may be added to the mix preferably in amounts of from 0.3 to 1.0% by weight of the water content in order to expedite the transfer of the water to the gypsum. Conventional plasticisers, such as polyvinyl acetate may also be added. These are usually added as emulsions in amounts of from 2 to 10 parts (solids) by weight per 100 parts of binder.

The preferred method of mixing of the ingredients is first to tumble the filler whilst gradually adding the water, and the plasticiser and wetting agent, if used, and then to add the gypsum and the reinforcing fibre, if used.

The pressure under which the composition should be compressed should generally be at least 2, and preferably from 2 to 7 kg cm-2.

Building components according to the invention may be used, for example as fire doors, wall panels or marine bulkheads. In addition, by using an appropriately shaped mould certain slightly more complex shapes can be produced, for example corners for column casings.

The invention is illustrated by the following Examples.

EXAMPLE 1 A building panel in accordance with the invention was prepared suitable for a door capable of passing the so-called "one hour" test (B.S. 476 Part 8, 1972). 8.6 kg of water were mixed with 3 Kg of an aqueous P.V.A.

emulsion (solids content 45%) and 112 g of an anionic detergent (Teepol-Registered Trade Mark). The resultant liquid was sprayed onto 5 kg of dry perlite (E.P.U.

100/35) whilst the perlite was tumbled in a "BMW-Rapid" mixer. 200 g of SN glass fibres, 10 kg of a-plaster and 10 kg of p- plaster were then added, and tumbling was continued until the mixture was substantially uniform. The uniform mixture was turned into a mould of dimensions 74 x26t to a thickness of approximately 4+".

Pressure was applied (4 kg cm-2) and the 4g layer compressed to approximately 1+".

The resulting door core had a density when dry of between 600 and 700 kg/m3.

EXAMPLE II In the same manner as in Example I, but omitting the P.V.A. emulsion, the following ingredients were combined: 4 Kg plaster 1 Kg Perlite (EPU/35) 2.2 Kg water 20 g anionic detergent (Teepol) 200 g 1 glass fibres.

The resulting composition was compressed in a mould at a pressure of 4 Kg cm. The resulting panel was tough and suitable for use as a ships bulkhead, and of passing the "Standard Fire Test" described in Regulation 3, of Chapter II-2 of "Safety of Life at Sea" (1974). The panel had good screw-holding properties and could be surfaced with a decorative material such as a wood veneer or a plastics laminate (e.g. a melamine, P.V.C. or polyester laminate).

Using this composition, panels were made having thicknesses of from 10 mm to 30 mm.

EXAMPLE III In the same manner as in Example II, but omitting the anionic detergent, the following ingredients were combined: 4 Kg p-plaster 1 Kg Perlite 2.4 Kg water 80 g iN glass fibres.

The resulting composition was compressed in a mould at a pressure of4 Kg cm. The resulting dry component was light, and suitable for use as a column casing in a position where impacts are likely to be slight or non-existent. Using the composition, panels were made having thicknesses of from 10 to 30 mm.

WHAT WE CLAIM IS: 1. A process for producing a building component, which process comprises mixing a filler having the capacity to absorb water whilst remaining dry (as hereinbefore defined) with an amount of water insufficient to convert the filler into a nonpowder or slurry forms, combining gypsum with the mixture, and mixing until the composition is substantially uniform, filling a mould with the composition, and compressing the composition in the mould thereby to expel the water from the filler and bring the water into intimate contact with the gypsum thereby to cause the gypsum to set.
2. A process as claimed in Claim 1 wherein the filler is one which will absorb at least twice its weight of water whilst remaining dry.
3. A process as claimed in Claim 1 or Claim 2, wherein the filler is perlite, kieselghur and vermiculite.
4. A process as claimed in any one of Claims 1 to 3, wherein the amount of water used is approximately 40 parts by weight per 100 parts by weight of the binder.
5. A process as claimed in any one of Claims 1 to 4, wherein a wetting agent is incorporated into the composition, to expedite the transfer of the water to the binder.
6. A process as claimed in Claim 5,

wherein the amount of wetting agent is from 0.3 to 1.0% by weight based on the weight of water.
7. A process as claimed in any one of Claims 1 to 6, wherein a plasticiser is incorporated into the composition.
8. A process as claimed in any one of Claims 1 to 7, wherein reinforcing fibres are incorporated in the composition.
9. A process as claimed in Claim 8 wherein the reinforcing fibres are natural fibres or synthetic polymer fibres.
10. A process as claimed in Claim 8, wherein the fibres are glass fibres.
11. A process as claimed in any one of Claims 8 to 10, wherein the fibres have an average length of from +" to IN.
12. A process as claimed in any one of Claims 8 to 11, wherein the fibres constitute from 1 to 5% by weight of the composition.
13. A process as claimed in any one Claims 8 to 12 wherein the fibres are mixed into the composition by tumbling.
14. A process as claimed in any one of Claims 1 to 13, wherein the pressure applied during compression of the composition is from 2 to 7 Kg cam~2.
15. A process for making a building component substantially as hereinbefore described with reference to any one of the Examples.
16. A building component when prepared by a process as claimed in any one of Claims 1 to 15.
17. A fire-door, a ship's bulkhead, or cladding for a column, comprising a component as claimed in Claim 16.