CA1057184A - Unique fire retardant particleboard and special process for manufacture - Google Patents
Unique fire retardant particleboard and special process for manufactureInfo
- Publication number
- CA1057184A CA1057184A CA227,838A CA227838A CA1057184A CA 1057184 A CA1057184 A CA 1057184A CA 227838 A CA227838 A CA 227838A CA 1057184 A CA1057184 A CA 1057184A
- Authority
- CA
- Canada
- Prior art keywords
- particles
- range
- borax
- sulfuric acid
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N9/00—Arrangements for fireproofing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B21/00—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board
- B32B21/02—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board the layer being formed of fibres, chips, or particles, e.g. MDF, HDF, OSB, chipboard, particle board, hardboard
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B21/00—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board
- B32B21/04—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board comprising wood as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B21/042—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board comprising wood as the main or only constituent of a layer, which is next to another layer of the same or of a different material of wood
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/04—Interconnection of layers
- B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
- C08L61/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C08L61/22—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds
- C08L61/24—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds with urea or thiourea
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K21/00—Fireproofing materials
- C09K21/02—Inorganic materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/30—Properties of the layers or laminate having particular thermal properties
- B32B2307/306—Resistant to heat
- B32B2307/3065—Flame resistant or retardant, fire resistant or retardant
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2607/00—Walls, panels
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L97/00—Compositions of lignin-containing materials
- C08L97/02—Lignocellulosic material, e.g. wood, straw or bagasse
Abstract
ABSTRACT OF THE DISCLOSURE
A unique fire retardant particleboard is manufactured by a special process of treating the particles prior to consolidation into a particleboard.
The process encompasses the use of boron compounds such as, for example, boric acid and borates, in combination with acids of sulfur, particularly sulfuric acid.
A unique fire retardant particleboard is manufactured by a special process of treating the particles prior to consolidation into a particleboard.
The process encompasses the use of boron compounds such as, for example, boric acid and borates, in combination with acids of sulfur, particularly sulfuric acid.
Description
The present invention is broadly concerned with a fire retardant particleboard and with its special process of manufacture. In accordance with an aspect of the present invention wood particles are treated with boron compounds such as, for example, ~oric acid or alkali metal borates in combination with sulfur acids, such as, for example, sulfuric acid, prior to their consolidation into a particleboard panel.
It is well known in the art to produce wood particleboard panels by various processes and techniques. In general, particles such as, for example, wood particles of various sizes and geometrical configurations, are consolidated using various glue or binder mixes such as urea formaldehyde, phenol formaldehyde, melamine formaldehyde, acid phenol resins, etc., under heat and pressure. Typical processes are described in U.S. Patent 2,642,371 issued June 23, 1953, inventor, Fahrni, entitled "Composite Wooden Board", and in U.S. Patent 2,686,143, issued August 10, 1954, inventor, Fahrni, entitled "Process for Manufacturing a Composite Wooden Board".
It is also known in the art to use, with the chips~ added chemicals designed to reduce the fire hazard of these products. Many compounds have been suggested and used in order to meet various fire underwirters tests such as, for example, the 25 foot tunnel flame spread rating. Smoke rating tests must also be met in many installations for these products. Typical patents covering developments in this field are U.S. Patent No. 3,383,274, issued May 14, 1968, inventor: Craig, entltled "Flame Proofing of Construc-tion Material~", and U.S. Patent No. 3,360,822, issued December 28, 1971, inventor: Carmellini, entitled "Acoustical and Fire Resistant Particle-board". These patents are assigned to the applicant of the present invention.
It is also known in the art to use borates to produce so-called "Borate Fire Retardant Systems", by various processes. One method used is to treat the green chips with Polybor (Registered Trade Mark of U.S. Borax & Chem. Corp. Los Angeles, Calif.~ sodium borate, (Na2B8O13.4H2O~, e;ther in solution or as a dry powder. It is then conventional to add powdered boric acid, (H3B03), into the resin mix prior to using the resin mix to consolidate the treated wood chips. The addition of the boric acid to the -1- . ~
~L05718~
glue mix is required since all sodium borates such as, for example, Na2B8O13.4H2O have a relatively high pH such as, for example, about 7 which retards the cure cycle particularly when using a urea-formaldehyde resin. Thls retarding effect is compensated to some extent by the addition of a strongly buffered catalyst such as, for example, boric acid to the glue mix. Boric acid in the glue mix tends to alter the wood-resin interface pH and thus allow the normal cure cycle~
Certain troublesome problems are, however, encountered when the boric acid is added to the glue mix. One limiting factor as to the amount of boric acid which can be added to the glue mix is dictated by the viscoslty of the resin which can be handled by the resin spray system. Also great difficulty is encountered in securing a uniform distribution of the boric acid throughout the resin system particularly a urea-formaldehyde system. High speed expensive mixing equipment is required to secure a satisfactory dispersion of the powdered boric acid. Also, since the solubility of the boric acid in this system is slight, the greater amount of the boric acid will remain in suspenslon, thus causing difficulty in spraying~ and plug-ups in the spray system~ Furthermore, when using boric acid in the resin mix, it is necessary to increase the resin content of the finished board to compensate for the poor resin distribution due to the larger nozzles needed to spray the boric acid suspension.
The present invention in one of its aspects provides a high quality fire retardant particleboard using boron compounds in con~unction with sulfuric acid, in the direct treatment of the green chips.
Thus, by one broad aspect of this invention a process is provided for the manufacture of an improved fire resistant wood part particleboard which comprises: spraying wood particles with an aqueous solution of a boron compound and sulfuric acid, said boron compound selected from the group, borax decahydrate (Na2B407. 10H20), borax dehydrated (Na2B407), borax pe~tahydrate (Na2B407.5H20), polybor (Na2B8013.4H20)~ salts of meta or ortho boric acids and boric acid in conjunction with the borate and sulfuric acid to give the proper Na20 to B203 ratio for maximum solubility of the final mixture;
said sulfuric acid being of 90% to 98% concentration which is present in a weight ratio of from 1.5 to 4.0 boron compound to 1 of sulfuric acid; with the aqueous solution having a pH in the range of 4.5 to 6.0, and wherein the amount sprayed intO the particles is in the range of 10% to 40% by weight based on the weight of the dry wood particles, the solution is heated to temperatures of 150F. to 225F. before use; thereafter conditioning and drying the wood particles to moisture content of 3% to 7%; applying a resin glue system of urea formaldehyde, and wherein the amount used is in the range of 2% to 12% by weight based on the wood particles; and consolidating the particles under heat at a temperature in the range of 275F. to 360F. and pressure in the range of 200 psi to 300 p9i for a time period in the range of 5 minutes to 20 minutes.
By another aspect of this inventlon, a process is provided for the manufacture of an improved fire resistant wood particleboard and for improving the cure cycle of the resin glue system which comprises: Spraying wood particles with an aqueous solution of borax (Na2B407) and sulfuric acid of 96% concentration, said solution containing, by weight, 35% borax, and wherein the weight ratio of borax to sulfuric acid is 52 to 21; said aqueous solution having a pH in the range of 4.5 to 6.0, and wherein the amount of aqueous solution sprayed onto the particles is in the range of 15% to 35% by weight based on the weight of the dry wood particles, and said aqueous solution is sprayed at a temperature in the range of 150F. to 225F. and wherein said particles, after spraying, are allowed to stand before being dried for a time period of ten minutes; apply a urea formaldehyde resin glue system to said wood particles wherein the amount of said resin glye system used is in the range of 2% to 12% by weight based on the wood particles; and then consolidating said wood particles under heat and pressure into a fire resistant particle-board.
By still another aspect of this invention a process is provided for the manufacture of an improved fire resistant wood particleboard and for improving the cure cycle of the resin glue system which comprises: spraying wood particles with an aqueous solution of borax (Na2B407.XH20) wherein X has a value of from 0 to 10~ and sulfuric acid, said solution containing 35% by weight of borax, wherein the weight ratio of borax to sulfuric acid is 1.5 to 4.0 borax to 1 of acld~ wherein the amount of solution sprsyed is 25% by weight based on the dry particles, the solution being sprayed at a temperature of 170F and having a pH in the range of 4.5 to 6.0; thereafter conditioning the sprayed particles for lO to 20 minutes; then drying the particles and applying 2% to 12% by weight of a urea formaldehyde glue system to said particles, followed by consolidating said particles into a particleboard at a pressure of 200 psi to 300 psi, at a temperature in the range of 275F to 360 F for a time period of 10 to 20 minutes.
As seen above, the resin mix, especially a urea - 3a _ 105718~
formaldehyde resin mix, is not diluted with boric acid and thereby is more stable and more effective permitting the use of less resin, all other factors being equal. Also, the expensive step heretofore required of adding boric acid to the resin mix to secure a borate system fire retardant particleboard is eliminated.
The present inVentiOn in one of its aspects may be more fully understood by reference to the drawing which diagramatical-ly illustrates one embodiment of the same. Referring to the drawing~ raw wood finish is intro- -. , . , , . _ , . . , _, . . .. .. . . .
105718~
duced into grinder or flaker 2 as illustrated by line 1. The flakes orchips are then passed through a blower 3 into a section of a blow pipe 8.
The chips may be of any size and configuration as those known in the art for the manufacture of particle boards. They may, for example, have lengths of 5 to 50 mm,, widths of 5 to 10 mm., and thicknesses of from 1 to 5 mm. It is preferred that the chips have a moisture content above 100%, such as, for example, 125% to 150%, as for example, of 135% based on the dry wood.
In blow pipe apparatus 8 the flakes are sprayed with fire retar-dant solution from spray nozzles 9 or equivalent applicators. The fire retardant solution comprises a borate, preferably a mixture of borates introduced into storage tank 4 by means of line 5 and sulfuric acid intro-duced by means of line 6. The fire retardant solution is passed to nozzles 9 by means of pump 7.
As mentioned above, the fire retardant solution comprises a boron compound, or a borate, or a mixture of borates and sulfuric acid. Boric acid is not satisfactory for application to the green chips since the chips carry no more than 5% boric acid. Above this quantity the excess boric acid falls away from the chips surfaces. The preferred acid is sulfuric acid, preferably 90% - 98%, such as, for example, 96% concentration.
The borate may be selected from the class consisting of borax decahydrate (Na2B407.10H20), borax dehydrated (Na2B407), borax pentahydrate (Na2B407.5H20), and Polybor (Na2B8013.4H20), or salts of meta or ortho boric acids. Also under certain conditions boric acid may be used in conjunction with the borate and sulfuric acid to give the proper Na20 to B203 ratio for maximum solubility of the final mixture. Thus, a preferred fire retardant spraying solution is a borax Na2B407.XH20 where X can be any value from 0 to 10, but preferably can be 0, 5, or 10 and 96% sulfuric acid present in the weight ratio of from 1.5 to 4,0 borax to 1 of sulfuric acid, preferably a weight ratio of 2-1/2 to 1, A desirable ratio is 52 parts by weight if anhydrous borax (or equivalent parts of borax penta or borax deca hydrate~ to 15 to 25 parts of -- 4 _ 96% sulfuric acid. A much preferred ratio is 52 parts of anhydrous borax to 21 parts of 96% sulfuric acid. The p~ of the fire retardant solution is in the range of 4.5 to 6.0, preferably 5.0 to 5.5, such as, for example, 5.25. The solution is adjusted to 30 - 50% solids, such as, for example, 40% by weight with water and heated to a temperature in the range of 150F
to 225F, such as, for example, 170F when sprayed on the chips.
The treated chips then continue through the blowpipe to a cyclone 10 and then to a wet storage bin 11. After some stand time (i.e.~ over ten minutes), in the bin or silo, the wet chips or particles are fed into a dryer 13 by means of either a blowpipe-cyclone setup (not shown) or a conveyor 12. The wet storage or conditioning bin 11 permits the chips to become thoroughly impregnated and saturated with the fire retardant solution.
After drying to a moisture content of 3% to 7%, such as, for example, 5%, the chips are taken through a blow pipe 14 to a cyclone 15 and then into a dry storage silo 16. From here the chips are conveyed by blowpipe or conveyor belt 17 to a screen 18 where the fines 20 are separated from the oversize particles 19; the fines are sent to a fine storage silo 22~ then through a glue applicator 24 and spread as face layers 27 and 29. The oversized are stored in 21, glued in a glue applicator 23, and used as a core layer 28.
Urea resin 25 and 26 is fed into the flue applicator. The resulting mat is pressed in a hot press 30 and sent through a board cooler 31 to glve a finished panel.
As pointed out, the resin glue mix, preferably a urea formaldehyde glue mix, is added to the chips by applicators 23 and 24. The amount of resin glue mix used is 2% to 12%, such as, for example, 8% by weight based on the weight of the dry chips. Core chips impregnated as described are introduced onto a caul at positions 27, 28 and 29.
The board is then hotpressed at position 30. The pressing condi-tionS will vary somewhat depending UpOn operating factors. If the board be, for example, a 0.7g/cc density 3/4" panel, the temperature would be 275F to 360F, such as, for example, 340F. The pressure is 200 to 300 psi, such as, for example, 250 psi for a time period of 5 to 20 minutes, such as, for lOS7184 example, 10 minutes~ The board is then dry cooled in zone 31 and then remoyed as a finished product, The boron compound and sulfuric acld are preferably mixed with water to give a 20% to 50%, such as, for example, a 35% by weight solution.
The amount of boron compound used as compared to the sulfuric acid used is to give a weight ratio in the range of 52 parts of anhydrous borax to 15 to 25 parts, preferably 21 parts of 96% acid. As mentioned, it is important that the pH of the solution be ~elow 6.5 in the range of 4.0 to 6.0, such as, for example, 5.25.
The amount of boron compound-sulfuric acid solution used based by weight on the dry flakes is in the range of 10% to 40%, preferably 15% to 35%, such as, for example, 25%.
In order further to illustrate an aspect of this invention, the following example is given.
EXAMPLE:
A 1:1 mixture of white fir and Douglas fir planer shavings were sprayed with a 30% solids solution of fire retardant consisting of 100 parts of sodium tetraborate decahydrate and 21 parts of 96% H2S04 in 122 parts of water. The solution was heated to 170F before spraying, to insure solution of the materials and to aid penetration into the wood. A total of 25 parts of fire retardant solids per 100 parts of dry wood was obtained. The treated wood particlt-s were then dried to a ~noisture content oP from 3 to 7% and sprayed with a commercial particleboard resin consisting of urea formalde-hyde condensates and ammonium sulfate catalyst. The level of resin used was 8% based on total resin solids to dry, treated wood.
The glued material was then spread to form a mat and pressed at 340F for ten minutes to give a particleboard having a density of .70 g/cc and a thickness of 3/4~'. This board was then cut into three sections 21" x 96" and tested in accordance with ASTM E84-68 25~ tunnel test. Test results gave a flame spread rating of 20 with a smoke rating of 0; this is a Class I rating.
It is well known in the art to produce wood particleboard panels by various processes and techniques. In general, particles such as, for example, wood particles of various sizes and geometrical configurations, are consolidated using various glue or binder mixes such as urea formaldehyde, phenol formaldehyde, melamine formaldehyde, acid phenol resins, etc., under heat and pressure. Typical processes are described in U.S. Patent 2,642,371 issued June 23, 1953, inventor, Fahrni, entitled "Composite Wooden Board", and in U.S. Patent 2,686,143, issued August 10, 1954, inventor, Fahrni, entitled "Process for Manufacturing a Composite Wooden Board".
It is also known in the art to use, with the chips~ added chemicals designed to reduce the fire hazard of these products. Many compounds have been suggested and used in order to meet various fire underwirters tests such as, for example, the 25 foot tunnel flame spread rating. Smoke rating tests must also be met in many installations for these products. Typical patents covering developments in this field are U.S. Patent No. 3,383,274, issued May 14, 1968, inventor: Craig, entltled "Flame Proofing of Construc-tion Material~", and U.S. Patent No. 3,360,822, issued December 28, 1971, inventor: Carmellini, entitled "Acoustical and Fire Resistant Particle-board". These patents are assigned to the applicant of the present invention.
It is also known in the art to use borates to produce so-called "Borate Fire Retardant Systems", by various processes. One method used is to treat the green chips with Polybor (Registered Trade Mark of U.S. Borax & Chem. Corp. Los Angeles, Calif.~ sodium borate, (Na2B8O13.4H2O~, e;ther in solution or as a dry powder. It is then conventional to add powdered boric acid, (H3B03), into the resin mix prior to using the resin mix to consolidate the treated wood chips. The addition of the boric acid to the -1- . ~
~L05718~
glue mix is required since all sodium borates such as, for example, Na2B8O13.4H2O have a relatively high pH such as, for example, about 7 which retards the cure cycle particularly when using a urea-formaldehyde resin. Thls retarding effect is compensated to some extent by the addition of a strongly buffered catalyst such as, for example, boric acid to the glue mix. Boric acid in the glue mix tends to alter the wood-resin interface pH and thus allow the normal cure cycle~
Certain troublesome problems are, however, encountered when the boric acid is added to the glue mix. One limiting factor as to the amount of boric acid which can be added to the glue mix is dictated by the viscoslty of the resin which can be handled by the resin spray system. Also great difficulty is encountered in securing a uniform distribution of the boric acid throughout the resin system particularly a urea-formaldehyde system. High speed expensive mixing equipment is required to secure a satisfactory dispersion of the powdered boric acid. Also, since the solubility of the boric acid in this system is slight, the greater amount of the boric acid will remain in suspenslon, thus causing difficulty in spraying~ and plug-ups in the spray system~ Furthermore, when using boric acid in the resin mix, it is necessary to increase the resin content of the finished board to compensate for the poor resin distribution due to the larger nozzles needed to spray the boric acid suspension.
The present invention in one of its aspects provides a high quality fire retardant particleboard using boron compounds in con~unction with sulfuric acid, in the direct treatment of the green chips.
Thus, by one broad aspect of this invention a process is provided for the manufacture of an improved fire resistant wood part particleboard which comprises: spraying wood particles with an aqueous solution of a boron compound and sulfuric acid, said boron compound selected from the group, borax decahydrate (Na2B407. 10H20), borax dehydrated (Na2B407), borax pe~tahydrate (Na2B407.5H20), polybor (Na2B8013.4H20)~ salts of meta or ortho boric acids and boric acid in conjunction with the borate and sulfuric acid to give the proper Na20 to B203 ratio for maximum solubility of the final mixture;
said sulfuric acid being of 90% to 98% concentration which is present in a weight ratio of from 1.5 to 4.0 boron compound to 1 of sulfuric acid; with the aqueous solution having a pH in the range of 4.5 to 6.0, and wherein the amount sprayed intO the particles is in the range of 10% to 40% by weight based on the weight of the dry wood particles, the solution is heated to temperatures of 150F. to 225F. before use; thereafter conditioning and drying the wood particles to moisture content of 3% to 7%; applying a resin glue system of urea formaldehyde, and wherein the amount used is in the range of 2% to 12% by weight based on the wood particles; and consolidating the particles under heat at a temperature in the range of 275F. to 360F. and pressure in the range of 200 psi to 300 p9i for a time period in the range of 5 minutes to 20 minutes.
By another aspect of this inventlon, a process is provided for the manufacture of an improved fire resistant wood particleboard and for improving the cure cycle of the resin glue system which comprises: Spraying wood particles with an aqueous solution of borax (Na2B407) and sulfuric acid of 96% concentration, said solution containing, by weight, 35% borax, and wherein the weight ratio of borax to sulfuric acid is 52 to 21; said aqueous solution having a pH in the range of 4.5 to 6.0, and wherein the amount of aqueous solution sprayed onto the particles is in the range of 15% to 35% by weight based on the weight of the dry wood particles, and said aqueous solution is sprayed at a temperature in the range of 150F. to 225F. and wherein said particles, after spraying, are allowed to stand before being dried for a time period of ten minutes; apply a urea formaldehyde resin glue system to said wood particles wherein the amount of said resin glye system used is in the range of 2% to 12% by weight based on the wood particles; and then consolidating said wood particles under heat and pressure into a fire resistant particle-board.
By still another aspect of this invention a process is provided for the manufacture of an improved fire resistant wood particleboard and for improving the cure cycle of the resin glue system which comprises: spraying wood particles with an aqueous solution of borax (Na2B407.XH20) wherein X has a value of from 0 to 10~ and sulfuric acid, said solution containing 35% by weight of borax, wherein the weight ratio of borax to sulfuric acid is 1.5 to 4.0 borax to 1 of acld~ wherein the amount of solution sprsyed is 25% by weight based on the dry particles, the solution being sprayed at a temperature of 170F and having a pH in the range of 4.5 to 6.0; thereafter conditioning the sprayed particles for lO to 20 minutes; then drying the particles and applying 2% to 12% by weight of a urea formaldehyde glue system to said particles, followed by consolidating said particles into a particleboard at a pressure of 200 psi to 300 psi, at a temperature in the range of 275F to 360 F for a time period of 10 to 20 minutes.
As seen above, the resin mix, especially a urea - 3a _ 105718~
formaldehyde resin mix, is not diluted with boric acid and thereby is more stable and more effective permitting the use of less resin, all other factors being equal. Also, the expensive step heretofore required of adding boric acid to the resin mix to secure a borate system fire retardant particleboard is eliminated.
The present inVentiOn in one of its aspects may be more fully understood by reference to the drawing which diagramatical-ly illustrates one embodiment of the same. Referring to the drawing~ raw wood finish is intro- -. , . , , . _ , . . , _, . . .. .. . . .
105718~
duced into grinder or flaker 2 as illustrated by line 1. The flakes orchips are then passed through a blower 3 into a section of a blow pipe 8.
The chips may be of any size and configuration as those known in the art for the manufacture of particle boards. They may, for example, have lengths of 5 to 50 mm,, widths of 5 to 10 mm., and thicknesses of from 1 to 5 mm. It is preferred that the chips have a moisture content above 100%, such as, for example, 125% to 150%, as for example, of 135% based on the dry wood.
In blow pipe apparatus 8 the flakes are sprayed with fire retar-dant solution from spray nozzles 9 or equivalent applicators. The fire retardant solution comprises a borate, preferably a mixture of borates introduced into storage tank 4 by means of line 5 and sulfuric acid intro-duced by means of line 6. The fire retardant solution is passed to nozzles 9 by means of pump 7.
As mentioned above, the fire retardant solution comprises a boron compound, or a borate, or a mixture of borates and sulfuric acid. Boric acid is not satisfactory for application to the green chips since the chips carry no more than 5% boric acid. Above this quantity the excess boric acid falls away from the chips surfaces. The preferred acid is sulfuric acid, preferably 90% - 98%, such as, for example, 96% concentration.
The borate may be selected from the class consisting of borax decahydrate (Na2B407.10H20), borax dehydrated (Na2B407), borax pentahydrate (Na2B407.5H20), and Polybor (Na2B8013.4H20), or salts of meta or ortho boric acids. Also under certain conditions boric acid may be used in conjunction with the borate and sulfuric acid to give the proper Na20 to B203 ratio for maximum solubility of the final mixture. Thus, a preferred fire retardant spraying solution is a borax Na2B407.XH20 where X can be any value from 0 to 10, but preferably can be 0, 5, or 10 and 96% sulfuric acid present in the weight ratio of from 1.5 to 4,0 borax to 1 of sulfuric acid, preferably a weight ratio of 2-1/2 to 1, A desirable ratio is 52 parts by weight if anhydrous borax (or equivalent parts of borax penta or borax deca hydrate~ to 15 to 25 parts of -- 4 _ 96% sulfuric acid. A much preferred ratio is 52 parts of anhydrous borax to 21 parts of 96% sulfuric acid. The p~ of the fire retardant solution is in the range of 4.5 to 6.0, preferably 5.0 to 5.5, such as, for example, 5.25. The solution is adjusted to 30 - 50% solids, such as, for example, 40% by weight with water and heated to a temperature in the range of 150F
to 225F, such as, for example, 170F when sprayed on the chips.
The treated chips then continue through the blowpipe to a cyclone 10 and then to a wet storage bin 11. After some stand time (i.e.~ over ten minutes), in the bin or silo, the wet chips or particles are fed into a dryer 13 by means of either a blowpipe-cyclone setup (not shown) or a conveyor 12. The wet storage or conditioning bin 11 permits the chips to become thoroughly impregnated and saturated with the fire retardant solution.
After drying to a moisture content of 3% to 7%, such as, for example, 5%, the chips are taken through a blow pipe 14 to a cyclone 15 and then into a dry storage silo 16. From here the chips are conveyed by blowpipe or conveyor belt 17 to a screen 18 where the fines 20 are separated from the oversize particles 19; the fines are sent to a fine storage silo 22~ then through a glue applicator 24 and spread as face layers 27 and 29. The oversized are stored in 21, glued in a glue applicator 23, and used as a core layer 28.
Urea resin 25 and 26 is fed into the flue applicator. The resulting mat is pressed in a hot press 30 and sent through a board cooler 31 to glve a finished panel.
As pointed out, the resin glue mix, preferably a urea formaldehyde glue mix, is added to the chips by applicators 23 and 24. The amount of resin glue mix used is 2% to 12%, such as, for example, 8% by weight based on the weight of the dry chips. Core chips impregnated as described are introduced onto a caul at positions 27, 28 and 29.
The board is then hotpressed at position 30. The pressing condi-tionS will vary somewhat depending UpOn operating factors. If the board be, for example, a 0.7g/cc density 3/4" panel, the temperature would be 275F to 360F, such as, for example, 340F. The pressure is 200 to 300 psi, such as, for example, 250 psi for a time period of 5 to 20 minutes, such as, for lOS7184 example, 10 minutes~ The board is then dry cooled in zone 31 and then remoyed as a finished product, The boron compound and sulfuric acld are preferably mixed with water to give a 20% to 50%, such as, for example, a 35% by weight solution.
The amount of boron compound used as compared to the sulfuric acid used is to give a weight ratio in the range of 52 parts of anhydrous borax to 15 to 25 parts, preferably 21 parts of 96% acid. As mentioned, it is important that the pH of the solution be ~elow 6.5 in the range of 4.0 to 6.0, such as, for example, 5.25.
The amount of boron compound-sulfuric acid solution used based by weight on the dry flakes is in the range of 10% to 40%, preferably 15% to 35%, such as, for example, 25%.
In order further to illustrate an aspect of this invention, the following example is given.
EXAMPLE:
A 1:1 mixture of white fir and Douglas fir planer shavings were sprayed with a 30% solids solution of fire retardant consisting of 100 parts of sodium tetraborate decahydrate and 21 parts of 96% H2S04 in 122 parts of water. The solution was heated to 170F before spraying, to insure solution of the materials and to aid penetration into the wood. A total of 25 parts of fire retardant solids per 100 parts of dry wood was obtained. The treated wood particlt-s were then dried to a ~noisture content oP from 3 to 7% and sprayed with a commercial particleboard resin consisting of urea formalde-hyde condensates and ammonium sulfate catalyst. The level of resin used was 8% based on total resin solids to dry, treated wood.
The glued material was then spread to form a mat and pressed at 340F for ten minutes to give a particleboard having a density of .70 g/cc and a thickness of 3/4~'. This board was then cut into three sections 21" x 96" and tested in accordance with ASTM E84-68 25~ tunnel test. Test results gave a flame spread rating of 20 with a smoke rating of 0; this is a Class I rating.
Claims (3)
1. Process for the manufacture of an improved fire resistant wood particleboard which comprises: spraying wood particles with an aqueous solution of a boron compound and sulfuric acid, siad boron compound selected from the group, borax decahydrate (Na2B4O7.10H2O), borax dehydrated (Na2B407), borax pentahydrate (Na2B4O7.5H2O), polybor (Na2B8O13.4H2O), salts of meta or ortho boric acids and boric acid in conjunction with the borate and sulfuric acid to give the proper Na2O to B2O3 ratio for maximum solubility of the final mixture; said sulfuric acid being of 90%
to 98% concentration which is present in a weight ratio of from 1.5 to 4.0 boron compound to 1 of sulfuric acid; with the aqueous solution having a pH in the range of 4.5 to 6.0, and wherein the amount sprayed into the particles is in the range of 10% to 40%
by weight based on the weight of the dry wood particles, the solution is heated to temperatures of 150°F. to 225°F. before use;
thereafter conditioning and drying the wood particles to moisture content of 3% to 7%; applying a resin glue system of urea formaldehyde, and wherein the amount used is in the range of 2% to 12% by weight based on the wood particles; and consolidating the particles under heat at a temperature in the range of 275°F. to 360°F. and pressure in the range of 200 psi to 300 psi for a time period in the range of 5 minutes to 20 minutes.
to 98% concentration which is present in a weight ratio of from 1.5 to 4.0 boron compound to 1 of sulfuric acid; with the aqueous solution having a pH in the range of 4.5 to 6.0, and wherein the amount sprayed into the particles is in the range of 10% to 40%
by weight based on the weight of the dry wood particles, the solution is heated to temperatures of 150°F. to 225°F. before use;
thereafter conditioning and drying the wood particles to moisture content of 3% to 7%; applying a resin glue system of urea formaldehyde, and wherein the amount used is in the range of 2% to 12% by weight based on the wood particles; and consolidating the particles under heat at a temperature in the range of 275°F. to 360°F. and pressure in the range of 200 psi to 300 psi for a time period in the range of 5 minutes to 20 minutes.
2. Process for the manufacture of an improved fire resistant wood particleboard and for improving the cure cycle of the resin glue system which comprises: spraying wood particles with an aqueous solution of borax (Na2B4O7) and sulfuric acid of 96% concentration, said solution containing, by weight, 35% borax, and wherein the weight ratio of borax to sulfuric acid is 52 to 21;
said aqueous solution having a pH in the range of 4.5 to 6.0, and wherein the amount of aqueous solution sprayed onto the particles is in the range of 15% to 35% by weight based on the weight of the dry wood particles, and said aqueous solution is sprayed at a temperature in the range of 150°F. to 225°F. and wherein said particles, after spraying, are allowed to stand before being dried for a time period of tem minutes; apply a urea formaldehyde resin glue system to said wood particles wherein the amount of said resin glue system used is in the range of 2% to 12% by weight based on the wood particles; and then consolidating said wood particles under heat and pressure into a fire resistant particle-board.
said aqueous solution having a pH in the range of 4.5 to 6.0, and wherein the amount of aqueous solution sprayed onto the particles is in the range of 15% to 35% by weight based on the weight of the dry wood particles, and said aqueous solution is sprayed at a temperature in the range of 150°F. to 225°F. and wherein said particles, after spraying, are allowed to stand before being dried for a time period of tem minutes; apply a urea formaldehyde resin glue system to said wood particles wherein the amount of said resin glue system used is in the range of 2% to 12% by weight based on the wood particles; and then consolidating said wood particles under heat and pressure into a fire resistant particle-board.
3. Process for the manufacture of an improved fire resistant wood particleboard and for improving the cure cycle of the resin glue system which comprises: spraying wood particles with an aqueous solution of borax (Na2B4O7.XH2O) wherein X has a value of from 0 to 10, and sulfuric acid, said solution containing 35% by weight of borax, wherein the weight ratio of borax to sulfuric acid is 1.5 to 4.0 borax to 1 of acid, wherein the amount of solution sprayed is 25% by weight based on the dry particles, the solution being sprayed at a temperature of 170 F and having a pH in the range of 4.5 to 6.0; thereafter conditioning the sprayed particles for 10 to 20 minutes; then drying the particles and applying 2% to 12% by weight of a urea formaldehyde glue system to said particles, followed by consolidating said particles into a particleboard at a pressure of 200 psi to 300 psi, at a temperature in the range of 275 F. to 360°F. for a time period of 10 to 20 minutes.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US48668674A | 1974-07-08 | 1974-07-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1057184A true CA1057184A (en) | 1979-06-26 |
Family
ID=23932864
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA227,838A Expired CA1057184A (en) | 1974-07-08 | 1975-05-27 | Unique fire retardant particleboard and special process for manufacture |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS519170A (en) |
| CA (1) | CA1057184A (en) |
| DE (1) | DE2530295A1 (en) |
| FI (1) | FI751707A (en) |
| FR (1) | FR2277669A1 (en) |
| NL (1) | NL7507884A (en) |
| SE (1) | SE7507307L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015085382A1 (en) * | 2013-12-10 | 2015-06-18 | Labuto César Augusto Dumont | Processes involving sulphuric acid addition, products obtained and use of said products |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2621739C2 (en) * | 1976-05-15 | 1985-10-03 | Chemische Fabrik Kalk GmbH, 5000 Köln | Process for the production of a flame retardant component for chipboard |
| DE2933755A1 (en) | 1979-08-21 | 1981-03-12 | Chemische Fabrik Kalk GmbH, 5000 Köln | METHOD FOR THE PRODUCTION OF FIRE-PROTECTED CHIPBOARDS OR -FORMED BODIES |
| DE3044861A1 (en) * | 1980-11-28 | 1982-07-01 | Chemische Fabrik Kalk GmbH, 5000 Köln | METHOD FOR THE PRODUCTION OF FIRE PROTECTED WOOD CHIPBOARDS OR MOLDED BODIES |
| DE19621606A1 (en) * | 1996-05-30 | 1997-12-04 | Picon Schmidt & Co Gmbh | Fire retardant for boards or molded parts made of chips or fibers and process for fire-resistant finishing of such boards or molded parts |
-
1975
- 1975-05-27 CA CA227,838A patent/CA1057184A/en not_active Expired
- 1975-05-31 JP JP50065978A patent/JPS519170A/ja active Pending
- 1975-06-09 FI FI751707A patent/FI751707A/fi not_active Application Discontinuation
- 1975-06-25 SE SE7507307A patent/SE7507307L/en unknown
- 1975-07-02 NL NL7507884A patent/NL7507884A/en unknown
- 1975-07-07 DE DE19752530295 patent/DE2530295A1/en active Pending
- 1975-07-07 FR FR7521241A patent/FR2277669A1/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015085382A1 (en) * | 2013-12-10 | 2015-06-18 | Labuto César Augusto Dumont | Processes involving sulphuric acid addition, products obtained and use of said products |
Also Published As
| Publication number | Publication date |
|---|---|
| SE7507307L (en) | 1976-01-09 |
| FR2277669A1 (en) | 1976-02-06 |
| DE2530295A1 (en) | 1976-01-22 |
| FI751707A (en) | 1976-01-09 |
| JPS519170A (en) | 1976-01-24 |
| FR2277669B1 (en) | 1979-05-11 |
| NL7507884A (en) | 1976-01-12 |
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