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Title:
METHOD OF MAKING A FIRE RESISTANT BUILDING PANEL
Document Type and Number:
WIPO Patent Application WO/2002/007964
Kind Code:
A1
Abstract:
A method of making a fire resistant building panel comprising two outer panel elements and an inner core sandwiched between the two outer panel elements is disclosed. The two outer panel elements are manufactured from a composition comprising particles of an exfoliated vermiculite, which particles are resinated with a thermosetting resin. The composition is formed into a layer and pressed at a suitable temperature and pressure to a thickness of between 3 mm and 9 mm and a suitable density. Thereafter, the two outer panels are adhered on either side of an inner coreto form the building panel. The building panel has good fire resistant properties.

Inventors:
SYMONS MICHAEL WINDSOR (ZA)
Application Number:
PCT/IB2001/001257
Publication Date:
January 31, 2002
Filing Date:
July 16, 2001
Export Citation:
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Assignee:
BALMORAL TECHNOLOGIES PTY LTD (ZA)
WINDSOR TECHNOLOGIES LTD (BS)
SYMONS MICHAEL WINDSOR (ZA)
International Classes:
B32B13/00; B32B19/04; C04B14/20; C04B26/10; (IPC1-7): B32B13/00; C04B26/12; C04B26/16; C04B28/00
Domestic Patent References:
WO1998037032A11998-08-27
Other References:
"CHEMICAL ABSTRACTS + INDEXES,US,AMERICAN CHEMICAL SOCIETY. COLUMBUS", CHEMICAL ABSTRACTS + INDEXES,US,AMERICAN CHEMICAL SOCIETY. COLUMBUS, vol. 97, no. 24, 13 December 1982 (1982-12-13), XP000392665, ISSN: 0009-2258
Attorney, Agent or Firm:
Gilson, David Grant (PO Box, 2024 Craighall, ZA)
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Claims:
CLAIMS
1. A method of making a fire resistant building panel comprising two outer panel elements and an inner core sandwiched between the two outer panel elements, including the steps of: (1) providing a composition for manufacture of the two outer panel elements, the composition comprising: (a) particles of an exfoliated vermiculite, which particles are resinated by either: (b) (i) applying to the particles of vermiculite a liquid thermosetting resin optionally with a catalyst and optionally dissolved in a suitable solvent or dispersed in an oil or in water; or (b) (ii) applying to the particles of vermiculite a dry powder thermosetting resin and if necessary a catalyst therefor, together with an adhesion promoter, so that the dry powder thermosetting resin adheres to the surfaces of the particles of vermiculite, or (b) (iii) applying to the particles of vermiculite a dispersion of a dry powder thermosetting resin in a finely divided inorganic material so that the dry powder thermosetting resin is intimately mixed with the particles of vermiculite ; whereafter any solvent or water is removed; (2) forming the composition of step (1) into a layer and pressing the layer at a temperature of from 120°C to 240°C inclusive and at a pressure of from 20 kg/cm2 to 75 kg/cm2 inclusive to a thickness of between 3 mm and 9 mm inclusive at a density of from 1150 to 1750 kg/m3 inclusive, to form the two outer panel elements, each panel element comprising 70% to 97% inclusive by mass of the vermiculite particles ; (3) providing an inner core; and (4) adhering the two outer panel elements on either side of the inner core to form the building panel.
2. A method according to claim 1 wherein in step (1) the particles of vermiculite are resinated by applying to the particles a liquid isocyanate thermosetting resin in an amount of from 2% to 20% inclusive of the combined mass of the resin and particles.
3. A method according to claim 1 wherein in step (1) the particles of vermiculite are resinated by applying to the particles a dry powder novolac phenol formaldehyde resin with a catalyst, in an amount of from 2% to 20% inclusive of the combined mass of the resin and particles, together with an adhesion promoter so that the dry powder novolac phenol formaldehyde resin adheres to the surfaces of the particles.
4. A method according to claim 3 wherein the adhesion promoter is water or a compound dissolved or dispersed in water.
5. A method according to claim 4 wherein the adhesion promoter is a solution of a polyvinyl alcohol in water.
6. A method according to claim 1 wherein in step (1) the particles of vermiculite are resinated by applying to the particles a dispersion of a dry powder novolac phenol formaldehyde resin in an amount of from 2% to 20% inclusive of the combined mass of the resin and particles, in a finely divided dry powder inorganic material so that the dry powder novolac phenol formaldehyde resin is intimately mixed with the particles of vermiculite.
7. A method according to claim 6 wherein the finely divided dry powder inorganic material is selected from a group consisting of undensified silica fume, fine particle size expanded perlite, bentonite, expanded clay, and fine particle size milled exfoliated vermiculite.
8. A method according to any one of claims 1 to 7 wherein each panel element comprises 85% to 95% inclusive by mass of the vermiculite particles.
9. A method according to any one of claims 1 to 8 wherein in step (2) the layer is pressed at a temperature of from 200°C to 220°C inclusive and at a pressure of from 60 kg/cm2 to 75 kg/cm2 inclusive to a thickness of from 3 mm to 6 mm inclusive.
10. A method according to any one of claims 1 to 9 wherein the inner core is selected from the group consisting of a panel formed from a foamed hydraulic binder; an engineered wood product; gypsum board; cement bound particle board; cement fibreboard; gypsum fibreboard; and a polymeric foam.
11. A method according to any one of claims 1 to 10 wherein in step (4) the two outer panel elements are adhesively adhered to the inner core.
12. A method according to any one of claims 1 to 11 which includes the step of providing an edging for attachment to the edges of the building panel.
13. A method according to claim 12 wherein the edging is made from the same composition as the two outer panel elements.
14. A fire resistant building panel comprising two outer panel elements and an inner core adherently sandwiched between the two outer panel elements, each outer panel element comprising 70% to 97% inclusive by mass of particles of an exfoliated vermiculite, bound together with a thermosetting resin, each outer panal element having a thickness of from 3 mm to 9 mm inclusive and a density of from 1150 to 1750 kg/m3 inclusive.
15. A building panel according to claim 14 wherein each outer panel element comprises 85% to 95% inclusive by mass of the vermiculite particles.
16. A building panel according to claim 14 or claim 15 wherein the thermosetting resin is selected from the group consisting of an isocyanate thermosetting resin and a novolac phenol formaldehyde resin.
17. A building panel according to any one of claims 14 to 16 wherein the inner core is selected from the group consisting of a panel formed from a foamed hydraulic binder; an engineered wood product; gypsum board; cement bound particle board; cement fibreboard; gypsum fibreboard; and a polymeric foam.
18. A building panel according to any one of claims 14 to 17 wherein the two outer panel elements are adhesively adhered to the inner core.
19. A building panel according to any one of claims 14 to 18 which includes an edging attached to the edges of the building panel.
20. A building panel according to claim 19 wherein the edging has the same composition as the two outer panel elements.
Description:
METHOD OF MAKING A FIRE RESISTANT BUILDING PANEL BACKGROUND TO THE INVENTION THIS invention relates to a method of making a fire resistant building panel, e. g a door or wall panel, and to building panels so formed.

SUMMARY OF THE INVENTION According to a first aspect of the invention there is provided a method of making a fire resistant building panel comprising two outer panel elements and an inner core sandwiched between the two outer panel elements, including the steps of: (1) providing a composition for manufacture of the two outer panel elements, the composition comprising: (a) particles of an exfoliated vermiculite which particles are resinated by either: (b) (i) applying to the particles of vermiculite a liquid thermosetting resin optionally with a catalyst and optionally dissolved in a suitable solvent or dispersed in an oil or in water; or (b) (ii) applying to the particles of vermiculite a dry powder thermosetting resin and if necessary a catalyst therefor, together with an adhesion promoter, so that the dry powder thermosetting resin adheres to the surfaces of the particles of vermiculite ; or (b) (iii) applying to the particles of vermiculite a dispersion of a dry powder thermosetting resin in a finely divided inorganic material so that the dry powder thermosetting resin is intimately mixed with the particles of vermiculite ; whereafter any solvent or water is removed; (2) forming the composition of step (1) into a layer and pressing the layer at a temperature of from 120°C to 240°C inclusive and at a pressure of from 20 kg/cm2 to 75 kg/cm2 inclusive to a thickness of between 3 mm and 9 mm inclusive at a density of from 1150 to 1750 kg/m3 inclusive, to form the two outer panel elements, each panel element comprising 70% to 97% inclusive by mass of the vermiculite particules ; (3) providing an inner core; and (4) adhering the two outer panel elements on either side of the inner core to form the building panel.

According to a second aspect of the invention there is provided a fire resistant building panel comprising two outer panel elements and an inner core adherently sandwiched between the two outer panel elements, each outer panel element comprising 70% to 97% inclusive by mass of particles of an exfoliated vermiculite, bound together with a thermosetting resin, each outer panal element having a thickness of from 3 mm to 9 mm inclusive and a density of from 1150 to 1750 kg/m3 inclusive.

DESCRIPTION OF EMBODIMENTS The crux of the invention is a method of making a fire resistant building panel, e. g a door or wall or roof panel, comprised of two outer panel elements or layers and an inner core sandwiched between the outer panel elements. Each of the outer panel elements has a high density and a low thickness, which imparts good fire resistant characteristics to the building panel.

Each of the panel elements is formed from a composition comprising particles of an exfoliated vermiculite, which particles have been resinated with a thermosetting resin.

By"finely divided exfoliated vermiculite particles"there is meant exfoliated vermiculite with a particle diameter of 0,5 mm or less. The particles preferably have a particle size of from 2 micron to 500 micron inclusive.

Vermiculite belongs to the group of hydrated lamina industrial minerals, which are all aluminum-iron magnesium silicates, high in silica. The resemble a muscovite (mica) in appearance. When subjected to heat, vermiculite exfoliates due to the inter lamina generation of steam. The pH is typically in the region of 9, specific gravity 2,5, melting point 1315°C, sintering temperature 1260°C and bulk densities are between 50 and 120g/litre. The product, exfoliated vermiculite is non-corrosive, non-combustible and non- abrasive. An example of a suitable grade is Zonolite No 5 or FPSV by WR Grace. Another example is RSU submicron by Phalaborwa Mining Company.

The second component of the composition is a thermosetting resin.

Firstly, the particles may be resinated with a liquid thermosetting resin optionally with a catalyst and optionally dissolved in a suitable solvent or dispersed in an oil.

An example of a liquid thermosetting resin is an MDI or urethane pre-polymer.

These are termed isocyanates and are compounds containing the group -N=C=O and are characterised by the general formula R (NOC) x wherein x is variable and denotes the number of NCO groups, and R denotes a suitable group. Examples of organic isocyanates include aromatic isocyanates, such as m-and p-phenylenediisocyanate, toluene-2, 4- and 2,6-diisocyanates, diphenylmethane-4, 4 diisocyanate and diphenylmethane-2, 4-diisocyanate and similar. These and similar are among those referred to as MDls in the industry.

An example of a water dispersible MDI is Suprasec 1042 by Industrial Urethanes of South Africa. A MDI suitable for oil dispersion is Duthane 2447 by Industrial Urethanes of South Africa It is to be noted that the term"isocyanate thermosetting resin"is intended to include the resins per se, i. e polyurethane resins, as well as those components which may be regarded as precursors of the resins, such as MDls and TDIs.

The optional solvent may be any suitable solvent and is preferably dichloromethane, the isocyanate thermosetting resin being dissolved in the dichloromethane at a concentration of 1,0% to 50% by mass, or liquid carbon dioxide or a blend of the two, suitable for spray application.

A further suitable liquid thermosetting resin is a phenol formaldehyde resole resin, an example being J2018L by Borden Chemical Company catalysed with the catalyst known as Phencat 10.

The particles may be resinated by immersion or preferably by spraying, following which the water or solvent is removed.

The particles are preferably resinated with the resin in an amount of from 3% to 20% inclusive of the combined mass of the resin and particles, i. e in a mass ratio of the resin to the particles of from 3: 97 to 20: 80, more preferably in an amount of from 5% to 12% inclusive of the combined mass of the resin and particles.

Secondly, the particles may be resinated with a dry powder thermosetting resin and if necessary a catalyst therefor, together with an adhesion promoter, so that the dry powder thermosetting resin adheres to the surfaces of the particles of vermiculite or perlite.

The particles of the thermosetting resin must have a particle size such that 98% pass a 200 mesh (74 micron) screen or finer.

An example of a suitable resin is a novolac phenol formaldehyde resin, which is used with suitable catalyst such as hexamethylene tetramine. A novolac phenol formaldehyde resin is a resin in which the molar ratio of phenol to formaldehyde exceeds parity. An example of a suitable resin with a particle size 98% passing a 200 mesh screen with a hot plate gel time at 150°C of between 40 and 120 seconds, and a flow in millimeters at 125°C between 30 and 75 mm, is code 602 by Schenectady Corporation of South Africa.

The adhesion promoter is preferably either water or a compound dissolved or dispersed in water, such as those selected from the group comprising water soluble, dispersible or miscible polymers, which are stable to electrolytes with film forming temperatures between-15°C and 40°C, polyvinyl alcohol, polyvinyl acetate, an acrylic such as styrenated acrylic, starch and casein.

The adhesion promoter is preferably a solution of from 2,5% to 10% inclusively of a polyvinyl alcohol in water, e. g Mowiol 4/88 by Cariant preferably also containing about 5% to 20% inclusive, more preferably about 10% of hexamethylene tetramine by weight of the polyvinyl alcohol. The solution may be applied to the particles at a rate of between 20% and 80% inclusive by mass of the mass of the particles.

The adhesion promoter may be applied before, together with or after application of the dry powder resin to the particles.

The particles are preferably resinated with the resin in an amount of from 3% to 20% inclusive of the combined mass of the resin and particles, i. e in a mass ratio of the resin to the particles of from 3: 97 and 20: 80, more preferably in an amount of from 5% to 12% inclusive of the combined mass of the resin and particles.

Thirdly, the particles may be resinated with a dispersion of a dry powder thermosetting resin, and if necessary a catalyst therefor, preferably a novolac phenol formaldehyde resin as discussed above, in a finely divided dry powder inorganic material, which is preferably light weight, such as for example undensified silica fume, fine particle size expanded perlite, bentonite, expanded clay, fine particle size milled exfoliated vermiculite, or the like.

The finely divided dry powder inorganic material must have a particle size of a maximum of 150 micron.

Firstly, the dry powder thermosetting resin is dispersed in the finely divided dry powder inorganic material, and then this dispersion is mixed with the particles of vermiculite so that there is little or no separation of the resin particles and the particles of vermiculite.

The particles of vermiculite are preferably resinated with the resin in an amount of from 3% to 20% inclusive of the combined mass of the resin and particles, i. e in a mass ratio of the resin to the particles of from 3: 97 to 20: 80, more preferably in an amount of from 5% to 12% inclusive of the combined mass of the resin and particles.

The dry powder thermosetting resin may be mixed with the finely divided dry powder inorganic material in a mass ratio of inorganic material to resin of from 1: 1 to 5: 1.

It is to be noted that each outer panel element comprises from 70% to 97% inclusive by mass, preferably 85% to 95% inclusive by mass of the vermiculite particles. These particles are bound together with a binder which is a thermosetting resin. The outer panel elements contain no other binder such as a hydraulic binder which has been set. In this regard, the finely divided dry powder inorganic material may comprise a hydraulic binder but this is being used not as a binder but solely as a carrier or dispersant for the finely divided dry powder thermosetting resin. There is no water present in the method and thus any hydraulic binder present cannot set.

The second step of the method of the invention is to form the composition into a layer and to press the layer, generally between the platens of a press, at a temperature between 120°C and 240°C inclusive, preferably at a temperature of from 200°C to 220°C inclusive, and at a pressure of from 20 kgicm2, to 75 kg/cm2, preferably at a pressure of from 60 kg/cm2 to 75 kg/cm2 to a thickness of from 3 mm to 9 mm inclusive, preferably from 3 mm to 6 mm inclusive, at a density of from 1150 to 1750 kg/m3 inclusive, preferably of from 1200 to 1550 kg/m3 inclusive.

The third step of the method of the invention is to provide an inner core.

The inner core may be for example: (a) a panel formed from a foamed hydraulic binder, e. g gypsum, Portland cement, a high alumina cement or a calcium aluminate cement; (b) an engineered wood product such as particle board, medium density fibreboard, oriented strand board, plywood, softboard, hardboard, or a laminated veneer lumber ; (c) a conventional building board such as gypsum board (sheetrock), cement bound particleboard, cement fibreboard, or gypsum fibreboard; (d) a polymeric foam having a density of from 7 kg/m3 to 45 kg/m3 inclusive, such as an expanded polystyrene foam, a closed or open cell polyurethane foam, a phenol formaldehyde resole resin foam, a polyvinyl chloride foam, a polyethylene foam, or a polypropylene foam.

The fourth step of the method of the invention is to adhere the two outer panel elements on either side of the inner core to form the building panel.

For example, the two outer panel elements may be adhesively attached to the inner core using, for example a dispersion in water of a polyvinyl acetate or an acrylic ; or a phenol formaldehyde resole resin which is acid catalysed; or a polyurethane precursor, or any other suitable adhesive, with the first three mentioned being the preferred adhesive systems.

The adhesion of the outer panel elements to the inner core may be assisted by pressing the two outer panel elements to the inner core in a press.

Alternatively, a suitable polymeric foam may be injected between the two outer panel elements firstly to form the inner core and secondly to adhere the inner core to the two outer panel elements. A suitable foam is a polyurethane foam.

The method of the invention may include the step of providing an edging for attachment to the edges of the building panel, particularly to protect the core of the panel and to provide structural strength. The edging may be made from the same composition as is used for the outer panel elements, or may be made from wood, metal, or a compressed expanded mineral product. The edging may be attached to the core or to the building panel in any suitable manner, for example using an adhesive as mentioned above.

As indicated above, the key to the performance of the building panel of the invention is the high density of the outer panel elements of the building panel, coupled with the thickness thereof. These features give the building panel of the invention a light weight, high impact strength, good flexural strength, good dimensional stability, good refractory characteristics which enable the building panel to withstand the temperatures associated with a fully developed fire without cracking for extended periods of time, and providing a suitable surface for decoration with veneers, foils, melamines and the like.

Examples of the invention will now be given.

Example 1 A door measuring 6 foot 6 inches (1.98m) by 2 foot 6 inches (0.76m), constructed of two vermiculite containing outer panel elements 4 mm thick, and with a density of 1350 kg/m3, glued to a particle board core 32 mm thick and with a density of 600 kg/m3, and with stiles and rails of pine, was tested in fire and lasted for 75 minutes when subjected to the standard ISO time/temperature curve, reaching a final furnace temperature of 1080°C.

Example 2 A wall panel measuring 2.7 m by 1.2 m and with a 58 mm overall thickness was formed from a 50 mm thick core of a gypsum foam panel with a density of 400 kg/m3 and weighing 48 kilograms, to which was adhesively joined two outer panel elements of vermiculite bound by 6% by mass of novolac resin Code 602 by Schenectady, each outer panel element being 4 mm thick and having a density of 1450 kg/m3 and weighing 18.8 kg. The panel included an all round structural frame of vermiculite with a density of 1250 kg/m3 and a cross-section of 50 mm by 25 mm and weighing 12 kg. The total panel weight was thus 98 kg, i. e 30 kg/m2, which is to be compared with a conventional panel fire rated at 120 minutes, which has a weight of 75 kg/m2 and a thickness of 80 mm.