FIELD OF INVENTION

The present invention relates to a flame retarding composition.

More particularly, the present invention relates to a flame retarding composition including a mixture of melamine components and melamine compounds.

BACKGROUND TO INVENTION

Flame retardants or flame retarding compositions are defined as materials that inhibit or resist the spread of fire. These are classified into various categories, though predominantly:

(a) Minerals including asbestos, compounds such as aluminium hydroxide, magnesium hydroxide, hydromagnesite, antimony trioxide, various hydrates, red phosphorus, and boron compounds, mostly borates;

(b) Tetrakis(hydroxymethyl)phosphonium salts, made by passing phosphine gas through a solution of formaldehyde and a mineral acid such as hydrochloric acid, predominantly used as flame retardants for textiles; and

(c) Synthetic materials, usually halocarbons which include organochlorines such as polychlorinated biphenyls (PCBs), chlorendic acid derivates (most often dibutyl chlorendate and dimethyl chlorendate) and chlorinated paraffins; organobromines such as polybrominated diphenyl ether (PBDEs), which be further broken down into pentabromodiphenyl ether (pentaBDE), octabromodiphenyl ether (octaBDE), decabromodiphenyl ether (decaBDE) and hexabromocyclododecane (HBCD); organophosphates in the form of halogenated phosphorus compounds such as tri-o-cresyl phosphate, tris(2,3-dibromopropyl) phosphate (TRIS), bis(2,3-dibromopropyl) phosphate, tris(l-aziridinyl)-phosphine oxide (TEPA), and others.

Brominated flame retardants or flame retarding compositions are a group of flame retardants that include organic compounds containing bromine. These are the major type of chemical flame retardants and are effective in plastics and textile applications. They are applied to prevent electronics, clothes and furniture from catching fire. They are produced synthetically with numerous variants with very varying chemical properties.

Several of the above chemicals are considered harmful and have been linked to liver, thyroid, reproductive/developmental, and neurological health side-effects. Polychlorinated biphenyls (PCBs) were banned in 1977 when it was discovered that they were toxic and the European Union has banned several types of brominated flame retardants in particular polybrominated diphenyl ethers from 2008.

Besides the conventional alternatives such as antimony or phosphorus- based retardants which have toxicological problems of their own, halogen- free alternatives are being explored. These alternatives include a technique to fuse flame retardants into products (to prevent chemicals leaking), nanoclays incorporating montmorillonite, and an entirely new plastic which produces water when burned called bishydroxydeoxybenzoin (BHDB). Inherently flame-resistant products are ideal and such plastics are applied in the aerospace industry though they are not cost-effective.

It is an object of the invention to suggest a flame retarding composition which will assist in overcoming the above obstacles. SUMMARY OF INVENTION

According to the invention, a flame retarding composition, includes a mixture of:

(a) at least one melamine component selected from the group consisting of:

(i) melamine; and

(ii) melamine homologues; and

(b) at least one melamine compound selected from the group consisting of:

(i) melamine polyphosphate;

(ii) melamine pyrophosphate; and

(iii) melamine cyanurate.

Also according to the invention, a method of preparing a flame retarding composition, includes the step of mixing

(a) at least one melamine component selected from the group consisting of:

(i) melamine; and

(ii) melamine homologues; and

(b) at least one melamine compound selected from the group consisting of:

(i) melamine polyphosphate;

(ii) melamine pyrophosphate; and

(iii) melamine cyanurate.

to form a flame retarding mixture adapted to be used as a flame retarding composition.

The melamine compound may be selected in terms of the respective required stability of the flame retarding composition.

Melamine polyphosphate may have a concentration in the mixture ranging from 0 wt% to 50 wt% or 10 wt% to 30 wt%. The melamine may be substantially pure.

The mixture may be ground to a size smaller than 10 microns and preferably smaller than 5 microns to form a finely ground flame retarding composition.

The finely ground flame retarding composition may be adapted to be added as a filler to the paint in the paint production process thereby replacing at least a part of the extender or filler in the paint.

The mixture may be adapted to be added in combination with other ingredients and/or through a semi-finished product.

The amount of mixture added to the paint may be between 15 wt% and 40 wt% of the total weight of the paint.

The mixture may have a white colour and/or be colourfast.

The flame retarding composition may be used in paints, glues, gels, plastics, pastes, foams and the like.

DETAILED DESCRIPTION OF EXAMPLE

The invention will now be described by way of example.

According to the invention, a flame retarding composition, includes a mixture of:

(a) at least one melamine component selected from the group consisting of:

(i) melamine; and

(ii) melamine homologues; and

(b) at least one melamine compound selected from the group consisting of: (i) melamine polyphosphate;

(ii) melamine pyrophosphate; and

(iii) melamine cyanurate.

The melamine compound is selected in terms of the respective required stability of the flame retarding composition.

The melamine polyphosphate can have a concentration in the mixture ranging from 0 wt% (when pure melamine is applied) to 50 wt%. and has been optimized with respect to reduction of smoke production. Reduction of smoke production was optimal at polyphosphate concentrations between 10 wt% and 30 wt%.

Melamine and melamine polyphosphate are mixed in the desired composition. Subsequently the mixture is ground to a size smaller than 10 microns and preferably smaller than 5 microns. The resulting finely ground flame retardant is added as filler to the paint in the paint production process replacing (part of) the extender or filler. Moreover, the flame retardant mixture can also be added in combination with other ingredients and/or through a semi-finished product. The amount of flame retardant added to the paint is between 15 wt% and 40 wt% of the total weight of the paint. While already excellent flame retarding paints are obtained between 20 wt% and 25 wt% of flame retardant. The mode of action of the flame retardant under consideration consists of endothermic degradation, thermal shielding and dilution of the gas phase. These three mechanisms together have proven to be very effective in retarding flames and fires. The flame retardant mixture has a white colour and is colourfast.

Melamine and its derivatives are non-toxic and are not listed as chemicals known cause cancer or reproductive toxicity. Accordingly the invention relates to a smoke reducing fire retardant paint and a method for the preparation thereof. However, the application of the filler as a flame retardant is not be limited to paints but can also be extended to glues, gels, plastics, pastes, foams and the like.

The fire retardant paint is prepared like any other paint containing an extender by replacing (part of) its extender by the flame retardant mixture. Extenders or fillers are generally inert inorganic minerals in fine powder form such as clays, chalk and other natural deposits. Commonly used mineral extenders are aluminium silicate), calcium carbonate and barium sulphate.

Accordingly the invention provides a method of preparing a flame retarding composition, which includes the step of mixing

(a) at least one melamine component selected from the group consisting of:

(i) melamine; and

(ii) melamine homologues; and

(b) at least one melamine compound selected from the group consisting of:

(i) melamine polyphosphate;

(ii) melamine pyrophosphate; and

(iii) melamine cyanurate.

to form a flame retarding mixture adapted to be used as a flame retarding composition.