GB2099830A

GB2099830A - Fire-retardant particle board

Info

Publication number: GB2099830A
Application number: GB8201298A
Authority: GB
Original assignee: Koppers Co Inc
Current assignee: Beazer East Inc
Priority date: 1981-06-01
Filing date: 1982-01-18
Publication date: 1982-12-15
Also published as: FR2506666A1; SE8107825L; DE3200403A1; JPS581548A

Abstract

Compressed particle board is formed from cellulosic particles, guanylurea phosphate, and an adhesive which evolves gases to form an intumescent fire retardant barrier with the guanylurea phosphate.

Description

SPECIFICATION Compressed particle board This invention relates to compressed particle board (also sometimes referred to as chip board, flake board and the like).

U.S. Patent Specification No. 3,383,274 discloses that compressed particle board having fire retardant properties can be formed from a salt of ammonia, a synthetic resin, and a wood particle material.

It has now been discovered that improved fire retardancy and dimensional stability can be obtained by substituting for the salt of ammonia (ammonium phosphate) taught by U.S. Patent Specification No. 3,383,274 guanylurea phosphate (GUP).

More particularly, in accordance with the present invention there is provided a compressed particle board formed from cellulosic particles, guanylurea phosphate, and an adhesive which evolves gases to form an intumescent fire retardant barrier with the guanylurea phosphate above compression temperature, i.e. the temperature at which the particle board was compressed or formed, when subjected to fire generating conditions.

It is believed that the improved fire retardancy is due to the fact the GUP renders both the adhesive resin and the wood particles fire resistant whereas ammonium phosphate is primarily effective only in treating the adhesive.

Preferably, the cellulosic particles which are employed to form the principal constituent of the compressed particle board of the invention are wood, but particles of other cellulosic materials, including hemp, jute, cotton and paper, can be used.

Adhesive resins which can be employed are those that evolve gases to form an intumescent fire retardant barrier with the GUP when subjected to fire generating conditions. Typical examples of suitable adhesive resins are isocyanate resins, urethane resins, phenolformaldehyde resins, urea-formaldehyde resins, urea-melamine-formaldehyde resins, ureadicyandiamide-formaldehyde resins, dicyandiamide-formaldehyde resins, and dicyandiamide-melamine-formaldehyde resins.

The guanylurea phosphate (GUP) is conveniently formed from water, and equimolar amounts of phosphoric acid and dicyandiamide.

Water is preferably used as the solvent and the ingredients are preferably heated with agitation at a temperature ranging from about 700C to about 900C in an inert reaction vessel, such as a glass or stainless steel vessel.

The particle board can be prepared by blending the cellulosic particles, the powder component of the adhesive resin and the GUP under ambient conditions, and then spraying the liquid component of the adhesive resin and a liquid hardener onto the dry mixture. The mixture can then be set aside, if necessary, to achieve the desired tack and then pressed into the desired shape.

In a typical application, particle board is composed of celluiosic particles in an amount ranging from about 40 percent to about 90 percent by weight, a total amount of resin adhesive ranging from about 3 percent to about 30 percent by weight, and the GUP in an amount ranging from about 7 percent to about 30 percent by weight.

The invention is further illustrated by the following Example which describes the preparation of the ceiling tile. All parts and percentages in said Example, and elsewhere in the specification and claims, are by weight unless otherwise specified.

Example Wood particles (50 Ibs) were blended with 4 Ibs. of urea formaldehyde resin adhesive powder and 17.5 Ibs. of guanylurea phosphate at a pH of between 2.8 and 3.2 buffered with 5 percent sodium hydroxide under ambient conditions. To this mixture there was then added by spraying at an air pressure of approximately 70-80 psi for from 1-2 minutes, 20.5 Ibs. of urea formaldehyde liquid resin and 0.95 Ibs. of an aqueous hardener (10 percent ammonium chloride). The mixture was then set aside for between 30 and 120 minutes to achieve the desired tack. On achieving the desired tack, the mixture was fed through the vibrating sieve (95 percent passing 1 50 Mm) into a mould which enters a cold pre-press producing the slats necessary to make ceiling tiles.The pre-press pressure was of the order of 1 600 psi of sample area. Time in the pre-press was approximately one minute. The pre-pressed slats were then placed in a three dimensional mould and hot pressed for one to two minutes at 160-1 700C.

and 850 psi of sample to produce the ceiling tiles.

The tiles may be sanded and painted, if desired.

When subjected to fire generating conditions an intumescent fire retardant barrier was formed with the guanylurea phosphate.

A comparison test was carried out by repeating the procedure described above except that ammonium polyphosphate (PHOSCHECK P30) was substituted as the fire retardant.

It was found by infrared analysis that phosphorylation or chemical bonding to the wood particles occurred with the guanylurea phosphate treated particle board, but not with the ammonium polyphophate treated particle board.

This indicates that the particle board of the invention is more dimensionally stable, more leach resistant and that the wood, in addition to the adhesive is rendered fire retardant.

Claims

1. A compressed particle board formed from cellulosic particles, guanylurea phosphate, and an adhesive which evolves gases to form an intumescent fire retardant barrier with the guanylurea phosphate above compression

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Compressed particle board This invention relates to compressed particle board (also sometimes referred to as chip board, flake board and the like). U.S. Patent Specification No. 3,383,274 discloses that compressed particle board having fire retardant properties can be formed from a salt of ammonia, a synthetic resin, and a wood particle material. It has now been discovered that improved fire retardancy and dimensional stability can be obtained by substituting for the salt of ammonia (ammonium phosphate) taught by U.S. Patent Specification No. 3,383,274 guanylurea phosphate (GUP). More particularly, in accordance with the present invention there is provided a compressed particle board formed from cellulosic particles, guanylurea phosphate, and an adhesive which evolves gases to form an intumescent fire retardant barrier with the guanylurea phosphate above compression temperature, i.e. the temperature at which the particle board was compressed or formed, when subjected to fire generating conditions. It is believed that the improved fire retardancy is due to the fact the GUP renders both the adhesive resin and the wood particles fire resistant whereas ammonium phosphate is primarily effective only in treating the adhesive. Preferably, the cellulosic particles which are employed to form the principal constituent of the compressed particle board of the invention are wood, but particles of other cellulosic materials, including hemp, jute, cotton and paper, can be used. Adhesive resins which can be employed are those that evolve gases to form an intumescent fire retardant barrier with the GUP when subjected to fire generating conditions. Typical examples of suitable adhesive resins are isocyanate resins, urethane resins, phenolformaldehyde resins, urea-formaldehyde resins, urea-melamine-formaldehyde resins, ureadicyandiamide-formaldehyde resins, dicyandiamide-formaldehyde resins, and dicyandiamide-melamine-formaldehyde resins. The guanylurea phosphate (GUP) is conveniently formed from water, and equimolar amounts of phosphoric acid and dicyandiamide. Water is preferably used as the solvent and the ingredients are preferably heated with agitation at a temperature ranging from about 700C to about 900C in an inert reaction vessel, such as a glass or stainless steel vessel. The particle board can be prepared by blending the cellulosic particles, the powder component of the adhesive resin and the GUP under ambient conditions, and then spraying the liquid component of the adhesive resin and a liquid hardener onto the dry mixture. The mixture can then be set aside, if necessary, to achieve the desired tack and then pressed into the desired shape. In a typical application, particle board is composed of celluiosic particles in an amount ranging from about 40 percent to about 90 percent by weight, a total amount of resin adhesive ranging from about 3 percent to about 30 percent by weight, and the GUP in an amount ranging from about 7 percent to about 30 percent by weight. The invention is further illustrated by the following Example which describes the preparation of the ceiling tile. All parts and percentages in said Example, and elsewhere in the specification and claims, are by weight unless otherwise specified. Example Wood particles (50 Ibs) were blended with 4 Ibs. of urea formaldehyde resin adhesive powder and 17.5 Ibs. of guanylurea phosphate at a pH of between 2.8 and 3.2 buffered with 5 percent sodium hydroxide under ambient conditions. To this mixture there was then added by spraying at an air pressure of approximately 70-80 psi for from 1-2 minutes, 20.5 Ibs. of urea formaldehyde liquid resin and 0.95 Ibs. of an aqueous hardener (10 percent ammonium chloride). The mixture was then set aside for between 30 and 120 minutes to achieve the desired tack. On achieving the desired tack, the mixture was fed through the vibrating sieve (95 percent passing 1 50 Mm) into a mould which enters a cold pre-press producing the slats necessary to make ceiling tiles.The pre-press pressure was of the order of 1 600 psi of sample area. Time in the pre-press was approximately one minute. The pre-pressed slats were then placed in a three dimensional mould and hot pressed for one to two minutes at 160-1 700C. and 850 psi of sample to produce the ceiling tiles. The tiles may be sanded and painted, if desired. When subjected to fire generating conditions an intumescent fire retardant barrier was formed with the guanylurea phosphate. A comparison test was carried out by repeating the procedure described above except that ammonium polyphosphate (PHOSCHECK P30) was substituted as the fire retardant. It was found by infrared analysis that phosphorylation or chemical bonding to the wood particles occurred with the guanylurea phosphate treated particle board, but not with the ammonium polyphophate treated particle board. This indicates that the particle board of the invention is more dimensionally stable, more leach resistant and that the wood, in addition to the adhesive is rendered fire retardant. Claims

1. A compressed particle board formed from cellulosic particles, guanylurea phosphate, and an adhesive which evolves gases to form an intumescent fire retardant barrier with the guanylurea phosphate above compression temperatures when subjected to fire generating conditions.

2. A compressed particle board as claimed in Claim 1 wherein the cellulosic particles are wood particles.

3. A compressed particle board as claimed in Claim 1 or 2, wherein the adhesive is formed from an isocyanate resin, a urethane resin, a phenolformaldehyde resin, a urea-formaldehyde resin, a urea-melamine-formaldehyde resin, a ureadicyandiamide-formaldehyde resin, a dicyandiamide-formaldehyde resin, or a dicyandiamide-melamine-formaldehyde resin.

4. A compressed particle board as claimed in Claim 1, 2 or 3, wherein the cellulosic particles are present in an amount of from about 40 percent to about 90 percent by weight, the resin adhesive is present in an amount of from about 3 percent to about 30 percent by weight, and the guanylurea phosphate is present in an amount of from about 7 percent to about 30 percent by weight.

5. A compressed particle board as claimed in Claim 1 substantially as hereinbefore described.

6. A method of preparing a compressed particle board which method comprises (a) blending cellulosic particles, a fire retardant amount of guanylurea phosphate, and an adhesive powder which will decompose, soften and evolve gases when subjected to fire generating conditions to form an intumescent fire retardant barrier with guanylurea phosphate, (b) spraying the resultant blend with a liquid resin adhesive (c) allowing the resultant mixture to achieve the desired tack, and (d) pressing the tacky mixture in a mould to the desired compression and shape.

7. A method of preparing a compressed particle board as claimed in Claim 1, substantially as described in the fdregoing Example.

8. An article whenever made from compressed particle board as claimed in Claim 1, 2, 3, 4 or 5.