GB2095683A

GB2095683A - Putty or mastic

Info

Publication number: GB2095683A
Application number: GB8204488A
Authority: GB
Original assignee: Dixon International Ltd
Current assignee: Dixon International Ltd
Priority date: 1981-02-16
Filing date: 1982-02-16
Publication date: 1982-10-06
Also published as: GB2095683B

Abstract

A composition suitable for use as a putty or mastic comprises, as a solid phase, fine particles comprising melamine formaldehyde resin, and ammonium phosphate, a polyhydroxy compound and polyvinyl acetate, the fine particles being mixed in a solution of a flexible stretchable film-forming adhesive polymer in a volatile solvent. Preferably the fine particles have a size less than 125 microns. Preferably the stretchable film-forming adhesive is polyvinyl butyral. Preferably the melamine-formaldehyde is crosslinked or the composition contains a crosslinking agent.

Description

SPECIFICATION Putty or mastic The present invention relates to mastic or putty.

Materials are known which when exposed to elevated temperature intumesce or swell to form a voluminous mass capable of acting as a barrier or sealant to the fumes and smoke arising from a conflagration. Such materials are referred to herein as "intumescent materials".

It is known to provide intumescent materials between door and windows and adjacent structures e.g. door frames and window frame, of a room, the intumescent material being applied to the doors and windows and/or the adjacent structures. It is also known to provide intumescent material in chinks between the door and window frames and the adjacent structures. In a conflagration, the intumescent material swells, fills and seals, preferably for at least one hour, existing gaps and gaps which form as a result of the heat between the door or window and the adjacent structure and the chinks to inhibit spread of smoke and fumes past the door or window.

Known intumescent materials are generally made from a slurry or paste which hardens to form the intumescent material.

Hitherto a substance capable of being used as a putty or mastic in the above-mentioned existing gaps and chinks or around a heat-resistant glass window and such that when hardened would intumesce under conflagration conditions has not been available.

Accordingly, it is an object of the invention to provide a putty or mastic which will harden or set and will intumesce under conflagration conditions.

In accordance with the present invention, there is provided a composition suitable for use as a putty or mastic comprising, as a solid phase, fine particles comprising melamine formaldehyde resin, an ammonium phosphate, a polyhydroxy compound and polyvinyl acetate, the fine particles being dispersed in a solution of a flexible, stretchable film-forming adhesive polymer in a volatile solvent.

The composition of the invention is preferably of a stiff pasty consistency similar to that of ordinary glaziers' putty and the composition is such that, on exposure to air, it will harden to a solid coherent mass.

By "fine particles" we mean particles having a size less than 125 microns, preferably less than 75 microns.

The stretchable film-forming adhesive polymer is preferably polyvinyl butyral.

The melamine formaldehyde resin may be crosslinked and/or the composition may contain a crosslinking agent. The melamine formaldehyde resin may be crosslinked by and/or the composition may contain dicyandiamide or guanidine.

The melamine formaldehyde resin may be crosslinked before mixing with the solution of the flexible stretchable film-forming polymer in the volatile solvent. Alternatively and preferably the melamine formaldehyde resin is uncrosslinked or substantially uncrosslinked when mixed with the solution of the stretchable film-forming polymer, a crosslinking agent such as dicyandiamide or guanidine is also mixed with the solution and the melamine-formaldehyde resin accordingly may become crosslinked on or after mixing with the solvent.

The ammonium phosphate is preferably monoammonium dihydrogen phosphate.

The polyhydroxy compound is preferably pentaerythritol or a sugar.

The volatile solvent may be isopropyl alcohol, methyl ethyl ketone or diacetone alcohol or a mixture thereof, optionally together with 1,1,1trichloroethane. The presence of 1,1,1trichloroethane, which is of low toxicity, reduces the fire hazard of the solvent. The composition hardens by evaporation of the solvent. The trowellable time of the composition depends on the rate of evaporation of the solvent, the trowellable time increasing as the rate of evaporation decreases.

Where the solvent comprises isopropyl alcohol, to retard the rate of evaporation of the solvent, preferably the solvent includes diacetone alcohol, methyl oxitol or other compound miscible with the isopropyl alcohol but less volatile than the isopropyl alcohol. It is preferable to use diacetone alcohol because, like isopropanol, it is reported to be of low toxicity.

Castor oil or other plasticizing agent may be incorporated into the composition to improve the flexibility and damp resistance of the hardened composition.

The solid phase of the composition of the invention is preferably made into fine particles by ball milling of the solid ingredients, either individually or together. To inhibit particles of the material being ball-milled from sticking together, solid CO2 and/or a small amount of finely divided activated silica as an anti-caking agent may be added to the material.

Alternatively the fine particles are produced by disc or hammer milling.

In preparing the composition, according to the invention, preferably the solid phase is provided by a mixture of uncrosslinked melamine formaldehyde resin, a crosslinking agent, ammonium phosphate, a polyhydroxy compound and polyvinyl acetate.

The solid phase of the composition may instead by made from scrap intumescent material originally prepared, for example, for intumescent seals for doors. The scrap material has to be rendered suitably fine and relatively coarse particles, such as wood flour, removed. The scrap materials may contain setting agent, e.g. plaster of Paris.

Alternatively specially prepared intumescent material may be used to prepare the fine particulate material.

The invention is illustrated by the following examples.

EXAMPLE 1 A mix was prepared from the following aiWe.dients: ammonium dihydrogen phosphate 42 g melamine formaldehyde resin (uncured) 38 g powder dicyandiamide 20 g pentaerythritol 8 9 Vinapol 1070 (water dispersible 1.5 g polyvinyl acetate powder) The mix was mixed with water (24 g) to give a paste. The paste was spread out in a layer about 1 cm thick in a tray and dried at 100 to 11 00C untii brittle and crumbly. (Heating above 1 300C is liable to cause the material to intumesce.) The dry crumb was then ground to powder (i.e. fine particles of size less than 75 microns) in a ball miil.

A polyvinyl butyral solution was made up from the following components: Butvar M79 (polyvinyl butyral 1 5 parts by weight castor oil 5 parts by weight isopropyl aicohol 72 parts by weight iaic,sstprle aicQhQJ l 8 parts by weight K O; K ^ The fine intumescent particular material was mixed with the polyvinyl butyral solution in the approximate proportions 100 parts by weight intumescent material to 40 parts by weight of the solution to give a paste of conventional putty-like consistency.

EXAMPLE 1A Example 1 was repeated but modified in that the polyvinyl butyral solution was made up using 37 parts by weight of isopropyl alcohol and 43 parts by weight of 1,1,1 -trichloroethane instead of isopropyl alcohol and diacetone alcohol in the amounts stated in Example 1.

EXAMPLE 2 In this example, scrap intumescent material was used. The scrap material had been originally prepared for use in intumescent fire seals for doors.

The scrap material was obtained as waste from the process described in Example 1 of our British patent application No. 4653/77, from the following ingredients: monoammonium dihydrogen phosphate 4200 g melamine formaldehyde resin powder 3800 g dicyandiamide 2000 g pentaerythritol 800 g Vinapol 1070 150 g wood flour (80 mesh) 250 g plaster of Paris 1100g water 2400 g The ingredients were mixed to form a slurry, which was put into holder strips and allowed to harden. Hardened excess slurry was the scrap used in the present example.

The scrap material was roughly broken~up and dried at elevated temperature (100-11 00C) until brittle and crumbly. The material was then reduced to powder by ball milling with anti-caking agent (precipitated silica) present and sieved through a 75 micron mesh sieve, which removed the wood flour. (Excessive amounts of anti-caking agent tend to reduce the degree of intumescence of the putty prepared.) The powder material was then mixed with a polyvinylbutyral solution to form putty. The relative proportions of the powder and the polyvinylbutyral solution and the composition of the polyvinylbutyral solution were as described in Example 1.

The putty prepared in Examples 1, A and 2 couid be worked into a gap and finished off with a putty knife or spatula. After hardening in air and on exposure to temperatures such as would occur in the gaseous combustion products of a conflagration, the putty puffed to about 5 times in its original thickness and constituted an effective seal.

EXAMPLE 3 A dry mix of the following ingredients was prepared: monoammonium dihydrogen phosphate 4200 g melamine resin 3800 g dicyandiamide 2000 g pentaerythritol 800 g Vinapol 150 g (Vinapol is polyvinyl acetate powder).

The dry mix was ball milled with solid CO2 and a small amount of activated silica to a powder having a particle size of less than 75 microns. The amount of activated silica was about 2% by weight based on the weight of the dry mix.

A solution of polyvinyl butyral in isopropyl alcohol was also prepared. This solution consisted of: Butvar N79 (polyvinyl butyral) 1 5 parts by weight castor oil 5 parts by weight isopropyl alcohol 72 parts by weight diacetone alcohol 8 parts by weight 30 parts by weight of the ball milled powder was mixed with 1 3 parts by weight of the polyvinyl butyral solution to give a smooth putty.

The putty spread well with a wet knife.

After standing exposed to the atmosphere for a week, the spread putty had set and intumesced well on heating to give a voluminous coherent mass.

Claims

1. A composition suitable for use as a putty or mastic comprising, as a solid phase, fine particles comprising melamine formaldehyde resin, and ammonium phosphate, a polyhydroxy compound and polyvinyl acetate, the fine particles being mixed in a solution of a flexible stretchable filmforming adhesive polymer in a volatile solvent.

2. A composition according to claim 1, being of a stiff paste consistency.

3. A composition according to either preceding claim, wherein the fine particles have a size less than the 125 microns.

4. A composition according to claim 3, wherein the particles have a size less than 75 microns.

5. A composition according to any preceding claim, wherein the stretchable film-forming adhesive polymer is polyvinyl butyral.

6. A composition according to any preceding claim, wherein the melamine formaldehyde resin is crosslinked and/or the composition contains a crosslinking agent.

7. A composition according to claim 6, wherein the melamine formaldehyde resin is crosslinked by and/or the composition contains dicyandiamide or guanidine as crosslinking agent.

8. A composition according to any preceding claim, wherein the ammonium phosphate is monoammonium dihydrogen phosphate.

9. A composition according to any preceding claim, wherein the polyhydroxy compound is pentaerythritol or a sugar.

10. A composition according to any preceding claim, wherein the solvent includes diacetone alcohol, methyloxitol or other compound miscible with the isopropyl alcohol but less volatile than the isopropyl alcohol.

11. A composition according to any preceding claim, further comprising a plasticizing agent.

12. A method of making a composition according to claim 1, comprising mixing together fine particles of melamine formaldehyde resin, a crosslinking agent, an ammonium phosphate, a polyhydroxy compound and polyvinyl acetate in a solution of a flexible stretchable film-forming adhesive polymer in a volatile solvent.

1 3. A composition according to claim 1, substantially or described herein in any of Examples 1, 1A,2and3.