CA1170394A - Production of structural panels using isocyanate/furfural binder - Google Patents
Production of structural panels using isocyanate/furfural binderInfo
- Publication number
- CA1170394A CA1170394A CA000399801A CA399801A CA1170394A CA 1170394 A CA1170394 A CA 1170394A CA 000399801 A CA000399801 A CA 000399801A CA 399801 A CA399801 A CA 399801A CA 1170394 A CA1170394 A CA 1170394A
- Authority
- CA
- Canada
- Prior art keywords
- isocyanate
- aldehyde
- binder
- furfural
- particles
- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/04—Polymeric products of isocyanates or isothiocyanates with vinyl compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/006—Polymeric products of isocyanates or isothiocyanates with aldehydes
-
- 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
.
The present invention is directed to the pro-duction of panels by a process which comprises coating cellulosic particles with a binder and thereafter compressing the coated particles at an elevated temperature. The binder of the present invention comprises a mixture of a polyisocyanate based on methylene di(phenylisocyanate) and an aldehyde which is soluble in said isocyanate and which is reactive therewith.
.
The present invention is directed to the pro-duction of panels by a process which comprises coating cellulosic particles with a binder and thereafter compressing the coated particles at an elevated temperature. The binder of the present invention comprises a mixture of a polyisocyanate based on methylene di(phenylisocyanate) and an aldehyde which is soluble in said isocyanate and which is reactive therewith.
Description
Mo-2221 PRODUCTION OF STRUCTURAL PANELS
USING ISOCYANATE/FURFURAL BINDER
BACKGROUND OF THE INVENTION
Many products are manufactured by the basic process of consolidating or joining together bodies of cellulosic materials using pressure, heat and a chemical binder. Included among them are wood-base products such as plywood, hardboard, particleboard and veneer-faced particleboard, and pressed or molded products made from vegetable fibers, such as cornstalks, straw or bagasse, or from other cellulosic materials such as pulp, shredded paper or the like. Typically, the binders used in making such products are thermosetting resins such as phenol-formaldehyde, resorcinol-formaldehyde, melamine-formaldehyde,urea-formaldehyde, urea-furfural and condensed furfuryl alcohol resins.
Other known binders include organic polyisocyanates, which have been used for gluing plywood and, either alone or together with urea- or melamine-formaldehyde resins, as particleboard adhesives. Typical of the types of binders disclosed in the art are polyisocyanate-formaldehyde mixtures (see U.S. Patents 3,919,017 and 3,930,110); polyisocyanates (see U.S. Patent 4,046,952 and British Patent 1,148,016); polyisocyanates in combination with urea-formaldehyde resin and/or phenol-formaldehyde resins (see U.S. Patent 4,209,433 and British Patent 1,148,016).
The use of furfural as a smoke suppressant in polyurethane foams is also known (see K. Ashida, "Novel Methods of Smoke Suppression in Isocyanurate Foams (1)", Advances in Urethane Science and Tech-nology, Volume 5, 1978). Finally, it has been suggested to blend furfural and/or furfuryl alcohol with an isocyanate which is a phosgenation product of an aniline-formaldehyde condensate and to there-after simultaneously trimerize the isocyanate Mo-2221 '3'~
and polymerize the furfural and/or furfuryl alcohol to thereby produce a furan-modified isocyanurate foam (see U.S. Patent 4,232,127).
As noted earlier, isocyanates have demonstrated a capability as a binder in the production of struc-tural panels from cellulosic particles. Isocyanates, and particularly polymethylene polyphenylisocyanates, can yield products with properties generally equal or superior to products produced from phenol-formaldehyde resins. However, one of the major problems associated with such isocyanates is their relatively higher cost when compared to phenol-formaldehyde resins. While there are many cost-saving advantages built into an isocyanate binder (such as faster press times, lower spread rates and low~r panel densities), the initial cost of the isocyanate has been a deterrent to their use.
DESCRIPTION OF THE INVENTION
The present invention is directed to the dis-covery that highly useful binders for the productionof panels, and particularly structural panels, from cellulosic particles can be provided by merely mixing polyisocyanates based on methylene di(phenylisocyanate) with an aldehyde which is soluble in the polyisocyanate and which is reactive therewith at a temperature of above 250F. It has been found that the addition of such aldehydes to the polyisocyanates not only significantly reduces the cost of the isocyanate binder, but also allows for the production of structural panels with improved physical properties when compared to panels produced using the isocyanate alone.
The present invention is thus directed to novel binder compositions and the use thereof in the pro-duction of structural panels from cellulosic particles.
The present invention is also directed to mixtures of Mo-2221 the binder of the present invention with cellulosic particles.
The isocyanate component of the binder of the present invention may be substantially any polyiso-cyanate based on methylene di(phenylisocyanate). By"polyisocyanate based on methylene di(phenylisocyanate)"
as used herein is meant polymethylene polyphenyl isocyanates, polyisocyanates having urethane groups which are obtained by reacting relatively small amounts of low molecular weight diols with methylene di(phenyl-isocyanate) [see, e.g., U.S. Patents 3,644,457;
3,394,164 and 4,115,429], carbodiimide group-containing polyisocyanates derived from methylene di(phenyl-isocyanate) [see, e.g., U.S. Patents 3,152,162;
3,384,653; 3,449,256; 4,014,935; 4,088,665 and 4,154,752], and mixtures thereof. Such isocyanates are well known in the art and are commercially available.
It is presently preferred to utilize polymethylene polyphenyl isocyanates (e.g., such as are produced by phosgenating an aniline-formaldehyde condensate) and it is most preferred to use a mixture of such isocyanates, wherein the mixture has the following average structure:
NCO ~ NCO NCO
~ CH2 - ~ CH2 n whérein n has a value of from 0.5 to 4 and preferably 0.5 to 3. Such isocyanate mixtures are known in the art and are commercially available.
As noted above, the aldehyde used in the present invention must be soluble in the isocyanate and must be reactive with said isocyanate. Specific aldehydes Mo-2221 found to be useful include furfural, benzaldehyde, pelargonaldehyde, cinnamaldehyde, nonylaldehyde, butyr-aldehyde, salicyaldehyde, chlorobenzaldehyde, ortho-tolylaldehyde, 2-naphthaldehyde, piperonal and vanillan.
The presently preferred aldehyde is furfural. While the aldehydes used herein have been described as being reactive with the isocyanate component, it is not known with certainty that the aldehyde is reactive with the isocyanate~ When the aldehydes herein are heated with the isocyanates herein, no characteristic aldehyde odor is detected. Thus, it is believed that the aldehyde and isocyanate do indeed react.
The aldehyde used in the present invention is used as such. The ratio of isocyanate to aldehyde is not critical and the optimum ratio for a given applica-tion can be determined by routine experimentation. In general, the amount of aldehyde can range from 1 to 50 parts by weight per 100 parts by weight of the mixtllre of aldehyde and isocyanate. The most preferred amount of aldehyde is from 3 to 30 parts by weight. It is pre-ferred that the amount of aldehyde added be such that the viscosity of the mixture is below 1,000 cP and preferably below 500 cP (Brookfield at 25C). It is most preferred that the viscosity of the mixture be between 25 and 300 cP. Of course, it is possible to use even higher amounts of aldehyde (e.g., up to 60%
or higher) if inert fillers such as fumed silica are added.
The binder system may be added or applied in any suitable manner, such as by brushing, dipping, spraying,roller coating, etc. In the preferred practice of the invention, the polyisocyanate and the aldehyde solution are added or applied together since they are inherently miscible. The quantity of binder needed in a particular application can be determined by simple experimentation.
Amounts in the range of 2-5% by weight, based on the dry weight of cellulosic material, have been used with Mo-2221 good results, although amounts of up to 20% by weight can also be used to advantage.
As will be appreciated, the novel isocyanate-aldehyde binder system may be used in the manufacture of a wide variety of products from many different cellulosic materials or mixtures of such materials.
By way of illustration, however, the invention will be described hereinafter particularly with respect to the manufacture of particleboard.
Particleboard is produced according to the invention by bonding together particles of wood or other cellulosic material using heat, pressure and a binder system comprising an isocyanate and aldehyde.
As mentioned above, the polyisocyanate component of the binder system may be substantially any polyisocyanate based on methylene di(phenylisocyanate). The preferred polyisocyanates are polyphenyl isocyanate and most preferably are of the average structure noted above.
The starting material for the particleboard comprises particles of cellulosic material, typically wood particles derived f~om lumber manufacturing waste such as planer shavings, veneer chips and the like, and engineered particles such as flakes, strands, wafers and the like. The methods for producing suitable particles are well known and conventional. If desired, mixtures of cellulosic particles may be used. Particle-board has been successfully produced, for example, from wood particle mixtures containing up to about 30% bark.
Typically, particles must be dried to between 4 and 10%
moisture content, thus causing substantial drying costs.
According to the present invention, particles may be used at moisture contents up to 20~. Generally, particles made from lumber waste materials contain about 10-20% moisture and may be used without further drying. Particles containing lesser amounts of moisture may be used; however, such generally needlessly adds to dryer cost.
Mo-2221 Particleboard is fabricated, according to pre-ferred practice, by spraying the particles with binder as they are tumbled or agitated in a blender. The amount of binder system used can generally range from 1 to 20% by weight depending upon the properties desired for the final product. Preferably, about 2-5% by weight of the binder system is added, based on the "oven dry"
weight of the particles. The binder system components are added as a preformed mixture, although they may be added separately and simultaneously, if desired. Other materials, such as wax sizing or fire retardant, may also be added to the particles during the blending step.
After sufficient blending to produce a uniform mixture, the coated cellulosic particles are formed into a loose mat or felt, preferably containing between about 6 and 20% moisture by weight. The mat is then placed in a heated press between caul plates which may, if necessary, be treated with a release composition and compressed to consolidate the particles into a board. Pressing '.imes, temperatures and pressures vary widely depending on the thickness of the board produced, the desired density of the board, the size of the particles used and other factors well known in the art. By way of example, however, for 1/2 inch thick particleboard of medium density, pressures of about 350-700 psi and temperatures of about 270-425F are typica~. Pressing times for 1/2 inch particleboard are typically about 2 to 7 minutes. As is generally known in the art, these parameters will vary depending on the desired thick-ness of the finished product. Because a portion of the moisture present in the mat will react with poly-isocyanate to form polyur~a, it does not have to be evaporated during the pressing cycle.
Mo-2221 '3't The invention is further illustrated, but is not intended to be limited by the following Examples in which all parts and percentages are by weight unless otherwise specified.
EXA~IPLES
In the Examples which follow, the isocyanates used were all phosgenation products of aniline-formaldehyde condensates and can be characterized as follows:
(a) Polyisocyanate A: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 410, a Brookfield viscosity at 25C of 225 centipoises (cP~, and an NCO content of 31.5%.
(b) Polyisocyanate B: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 410, a Brookfield viscosity at 25C of 291 cP and an NCO content of 31.5%.
(c) Polyisocyanate C: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 480, a Brookfie;d viscosity at 25C of 558 cP and an NCO content of 31.3%.
(d) Polyisocyanate D: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 510, a Brookfield viscosity at 25C of 2180 cP and an NCO content of 30.8%.
(e) Polyisocyanate E: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 610, a Brookfield viscosity at 25C of 4525 cP and an NCO content of 30.2%.
(f) Polyisocyanate F: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 720, a Brookfield viscosity at 25C of 11,350 cP and an NCO content of 29.9~.
Mo-2221 In the Examples which follow, the four viscosity values noted in Table I were selected and the amounts of furfural necessary to achieve each viscosity with each isocyanate were added in the amounts shown in Table I.
Panels were prepared by spraying the binder noted into a rotary drum blender which had previously been charged with Douglas fir ring-cut flakes. The binder was applied at a rate of 3 parts by weight binder per 97 parts of wood flakes. After sufficient tumbling to obtain a uniform distribution of the binder, the coated particles were removed from the blender and formed into a 24 inch by 28 inch by 1/2 inch panel in an electrically heated, hydraulically operated laboratory press. The press was maintained at a temperature of about 350F and a five-minute press cycle was used. Caul plates bound each side of the panel while it was being pressed. To prevent the panel from sticking to these plates, a 10% aqueous zinc stearate solution was sprayed on each plate. The resultant particleboards all had densities of 42 pounds per cubic foot.
The panels were then maintained at 72F, 65%
relative humidity until no change in weight was noted (this ge~erally took from 3 to 10 days). The panels were then tested using ASTM D-1037-72 to determine modulus of rupture (MOR), modulus of elasticity (MOE), tensile strength perpendicular to the surface (IB), 6-cycle MOR and wet MOR (MOR after a two-hour water boil and one-hour cold water soak). The results of such tests are as set forth in Table I.
Mo-2221 3'~
g 0 ~ J\ O O 1~ n ~1 ~ N ~ ~ ~ ~ N ~ N O CO
~1 ~ I` N ~ Ct~ _I N O il~ 0 O ~ O
m ~o u~o~~Or~oo~ o~u ct)~
o ~
o ~l ,~1 a~ ~o I
1~t o ~ o ~ co 1` ~ O ~I CO U~
O ~ ~ ~ ~ ~/ ~ ~ ~ ~1 ~D ~
O U~ ,1 ~ ~ r~ r~ l~ O O ~ ~ ~9 ~ O ~ ~ ~D OD ~ CO 1~ ~t ~ u~ a) H~ O . V~ ~ ~ L') ~ t-- O 0 1~'1 ~ ~ ~5 _ ~ ~ ~ ~ ~ ~ ~ ~ N ~ N ~ ) ~ ~ ~ N ~ N t~
Ir) O O L"l 1l ) 0 0 n ul 0 0 u~ O O u~ In O O u ) ~ 0 O u O .~ ~`1 O U l ~ ~ O ~ `1 N O l~r) N t~l O 11~ ~ N O L') t~ 1 O ~o N
~a ~1 O
O
h ~ U) ~ ~I) H
14 1~4 . O N ~D ~ L~ D ~ CD ~r r N CO ~ ~D N ~D CD r ~ O
n .......................
~U J~ ~D ~`J N ~1 ~-- ~r ~r Lr) _I CO 1` N a) Il ~ ~ 0 1` ~ 'D N a~ CO
~/ ~ 0~ _I N --1 N --1 ~I N --1 ~I N Ir1 .--1 N N ~ --1 N N ~) ,a ~a ~ ~8 _, J~
>~ D ~ m m m ~ a ~ a o U~
H
'a I ~-~ N tr~ D 1` CO ~ O ~--1 N ~ ~ 1~ ~ 1` 00 ~ O ~1 N (~) ~r ~ ~ ~1 _I ~ ~1 ~ ~ _I H ~I N ~ N N N
.,1 m The binder in this Example comprised a blend of 25 parts of Polyisocyanate D and 6 parts of benzaldehyde.
Three parts of the blend were mixed with 97 parts of wood chips as set forth in the previous Example. A
panel was produced as set forth in the previous Example.
The resultant panel had a specific gravity of 0.67, an IB of 111 psi, a MOR of 2500 psi and a wet MOR of 1866 psi.
The binder in these Examples comprised a blend of 25 parts of Polyisocyanate D and 6 parts of the aldehyde noted in Table II. Thirty-one parts of the blend were mixed with 1036 parts of wood chips as set forth in Example 1. Panels were produced as set forth in Example 1, with the exception that the press cycle was seven minutes instead of five minutes. The panels were tested for IB, MOR and wet MOR, with the results set forth in Table II being obtained.
TABLE II
IB MOR Wet MOR
Example Aldehyde (psi) (psi) (psi) 26 Cinnamaldehyde92 2366 1203 27 Salicyaldehyde90 2179 1089 28 Tolylaldehyde 110 2359 1209 29 Nonylaldehyde 99 2296 859 Butyraldehyde 72 1917 832 Mo-2221
USING ISOCYANATE/FURFURAL BINDER
BACKGROUND OF THE INVENTION
Many products are manufactured by the basic process of consolidating or joining together bodies of cellulosic materials using pressure, heat and a chemical binder. Included among them are wood-base products such as plywood, hardboard, particleboard and veneer-faced particleboard, and pressed or molded products made from vegetable fibers, such as cornstalks, straw or bagasse, or from other cellulosic materials such as pulp, shredded paper or the like. Typically, the binders used in making such products are thermosetting resins such as phenol-formaldehyde, resorcinol-formaldehyde, melamine-formaldehyde,urea-formaldehyde, urea-furfural and condensed furfuryl alcohol resins.
Other known binders include organic polyisocyanates, which have been used for gluing plywood and, either alone or together with urea- or melamine-formaldehyde resins, as particleboard adhesives. Typical of the types of binders disclosed in the art are polyisocyanate-formaldehyde mixtures (see U.S. Patents 3,919,017 and 3,930,110); polyisocyanates (see U.S. Patent 4,046,952 and British Patent 1,148,016); polyisocyanates in combination with urea-formaldehyde resin and/or phenol-formaldehyde resins (see U.S. Patent 4,209,433 and British Patent 1,148,016).
The use of furfural as a smoke suppressant in polyurethane foams is also known (see K. Ashida, "Novel Methods of Smoke Suppression in Isocyanurate Foams (1)", Advances in Urethane Science and Tech-nology, Volume 5, 1978). Finally, it has been suggested to blend furfural and/or furfuryl alcohol with an isocyanate which is a phosgenation product of an aniline-formaldehyde condensate and to there-after simultaneously trimerize the isocyanate Mo-2221 '3'~
and polymerize the furfural and/or furfuryl alcohol to thereby produce a furan-modified isocyanurate foam (see U.S. Patent 4,232,127).
As noted earlier, isocyanates have demonstrated a capability as a binder in the production of struc-tural panels from cellulosic particles. Isocyanates, and particularly polymethylene polyphenylisocyanates, can yield products with properties generally equal or superior to products produced from phenol-formaldehyde resins. However, one of the major problems associated with such isocyanates is their relatively higher cost when compared to phenol-formaldehyde resins. While there are many cost-saving advantages built into an isocyanate binder (such as faster press times, lower spread rates and low~r panel densities), the initial cost of the isocyanate has been a deterrent to their use.
DESCRIPTION OF THE INVENTION
The present invention is directed to the dis-covery that highly useful binders for the productionof panels, and particularly structural panels, from cellulosic particles can be provided by merely mixing polyisocyanates based on methylene di(phenylisocyanate) with an aldehyde which is soluble in the polyisocyanate and which is reactive therewith at a temperature of above 250F. It has been found that the addition of such aldehydes to the polyisocyanates not only significantly reduces the cost of the isocyanate binder, but also allows for the production of structural panels with improved physical properties when compared to panels produced using the isocyanate alone.
The present invention is thus directed to novel binder compositions and the use thereof in the pro-duction of structural panels from cellulosic particles.
The present invention is also directed to mixtures of Mo-2221 the binder of the present invention with cellulosic particles.
The isocyanate component of the binder of the present invention may be substantially any polyiso-cyanate based on methylene di(phenylisocyanate). By"polyisocyanate based on methylene di(phenylisocyanate)"
as used herein is meant polymethylene polyphenyl isocyanates, polyisocyanates having urethane groups which are obtained by reacting relatively small amounts of low molecular weight diols with methylene di(phenyl-isocyanate) [see, e.g., U.S. Patents 3,644,457;
3,394,164 and 4,115,429], carbodiimide group-containing polyisocyanates derived from methylene di(phenyl-isocyanate) [see, e.g., U.S. Patents 3,152,162;
3,384,653; 3,449,256; 4,014,935; 4,088,665 and 4,154,752], and mixtures thereof. Such isocyanates are well known in the art and are commercially available.
It is presently preferred to utilize polymethylene polyphenyl isocyanates (e.g., such as are produced by phosgenating an aniline-formaldehyde condensate) and it is most preferred to use a mixture of such isocyanates, wherein the mixture has the following average structure:
NCO ~ NCO NCO
~ CH2 - ~ CH2 n whérein n has a value of from 0.5 to 4 and preferably 0.5 to 3. Such isocyanate mixtures are known in the art and are commercially available.
As noted above, the aldehyde used in the present invention must be soluble in the isocyanate and must be reactive with said isocyanate. Specific aldehydes Mo-2221 found to be useful include furfural, benzaldehyde, pelargonaldehyde, cinnamaldehyde, nonylaldehyde, butyr-aldehyde, salicyaldehyde, chlorobenzaldehyde, ortho-tolylaldehyde, 2-naphthaldehyde, piperonal and vanillan.
The presently preferred aldehyde is furfural. While the aldehydes used herein have been described as being reactive with the isocyanate component, it is not known with certainty that the aldehyde is reactive with the isocyanate~ When the aldehydes herein are heated with the isocyanates herein, no characteristic aldehyde odor is detected. Thus, it is believed that the aldehyde and isocyanate do indeed react.
The aldehyde used in the present invention is used as such. The ratio of isocyanate to aldehyde is not critical and the optimum ratio for a given applica-tion can be determined by routine experimentation. In general, the amount of aldehyde can range from 1 to 50 parts by weight per 100 parts by weight of the mixtllre of aldehyde and isocyanate. The most preferred amount of aldehyde is from 3 to 30 parts by weight. It is pre-ferred that the amount of aldehyde added be such that the viscosity of the mixture is below 1,000 cP and preferably below 500 cP (Brookfield at 25C). It is most preferred that the viscosity of the mixture be between 25 and 300 cP. Of course, it is possible to use even higher amounts of aldehyde (e.g., up to 60%
or higher) if inert fillers such as fumed silica are added.
The binder system may be added or applied in any suitable manner, such as by brushing, dipping, spraying,roller coating, etc. In the preferred practice of the invention, the polyisocyanate and the aldehyde solution are added or applied together since they are inherently miscible. The quantity of binder needed in a particular application can be determined by simple experimentation.
Amounts in the range of 2-5% by weight, based on the dry weight of cellulosic material, have been used with Mo-2221 good results, although amounts of up to 20% by weight can also be used to advantage.
As will be appreciated, the novel isocyanate-aldehyde binder system may be used in the manufacture of a wide variety of products from many different cellulosic materials or mixtures of such materials.
By way of illustration, however, the invention will be described hereinafter particularly with respect to the manufacture of particleboard.
Particleboard is produced according to the invention by bonding together particles of wood or other cellulosic material using heat, pressure and a binder system comprising an isocyanate and aldehyde.
As mentioned above, the polyisocyanate component of the binder system may be substantially any polyisocyanate based on methylene di(phenylisocyanate). The preferred polyisocyanates are polyphenyl isocyanate and most preferably are of the average structure noted above.
The starting material for the particleboard comprises particles of cellulosic material, typically wood particles derived f~om lumber manufacturing waste such as planer shavings, veneer chips and the like, and engineered particles such as flakes, strands, wafers and the like. The methods for producing suitable particles are well known and conventional. If desired, mixtures of cellulosic particles may be used. Particle-board has been successfully produced, for example, from wood particle mixtures containing up to about 30% bark.
Typically, particles must be dried to between 4 and 10%
moisture content, thus causing substantial drying costs.
According to the present invention, particles may be used at moisture contents up to 20~. Generally, particles made from lumber waste materials contain about 10-20% moisture and may be used without further drying. Particles containing lesser amounts of moisture may be used; however, such generally needlessly adds to dryer cost.
Mo-2221 Particleboard is fabricated, according to pre-ferred practice, by spraying the particles with binder as they are tumbled or agitated in a blender. The amount of binder system used can generally range from 1 to 20% by weight depending upon the properties desired for the final product. Preferably, about 2-5% by weight of the binder system is added, based on the "oven dry"
weight of the particles. The binder system components are added as a preformed mixture, although they may be added separately and simultaneously, if desired. Other materials, such as wax sizing or fire retardant, may also be added to the particles during the blending step.
After sufficient blending to produce a uniform mixture, the coated cellulosic particles are formed into a loose mat or felt, preferably containing between about 6 and 20% moisture by weight. The mat is then placed in a heated press between caul plates which may, if necessary, be treated with a release composition and compressed to consolidate the particles into a board. Pressing '.imes, temperatures and pressures vary widely depending on the thickness of the board produced, the desired density of the board, the size of the particles used and other factors well known in the art. By way of example, however, for 1/2 inch thick particleboard of medium density, pressures of about 350-700 psi and temperatures of about 270-425F are typica~. Pressing times for 1/2 inch particleboard are typically about 2 to 7 minutes. As is generally known in the art, these parameters will vary depending on the desired thick-ness of the finished product. Because a portion of the moisture present in the mat will react with poly-isocyanate to form polyur~a, it does not have to be evaporated during the pressing cycle.
Mo-2221 '3't The invention is further illustrated, but is not intended to be limited by the following Examples in which all parts and percentages are by weight unless otherwise specified.
EXA~IPLES
In the Examples which follow, the isocyanates used were all phosgenation products of aniline-formaldehyde condensates and can be characterized as follows:
(a) Polyisocyanate A: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 410, a Brookfield viscosity at 25C of 225 centipoises (cP~, and an NCO content of 31.5%.
(b) Polyisocyanate B: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 410, a Brookfield viscosity at 25C of 291 cP and an NCO content of 31.5%.
(c) Polyisocyanate C: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 480, a Brookfie;d viscosity at 25C of 558 cP and an NCO content of 31.3%.
(d) Polyisocyanate D: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 510, a Brookfield viscosity at 25C of 2180 cP and an NCO content of 30.8%.
(e) Polyisocyanate E: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 610, a Brookfield viscosity at 25C of 4525 cP and an NCO content of 30.2%.
(f) Polyisocyanate F: a polymethylene poly-phenyl isocyanate having a weight average molecular weight of 720, a Brookfield viscosity at 25C of 11,350 cP and an NCO content of 29.9~.
Mo-2221 In the Examples which follow, the four viscosity values noted in Table I were selected and the amounts of furfural necessary to achieve each viscosity with each isocyanate were added in the amounts shown in Table I.
Panels were prepared by spraying the binder noted into a rotary drum blender which had previously been charged with Douglas fir ring-cut flakes. The binder was applied at a rate of 3 parts by weight binder per 97 parts of wood flakes. After sufficient tumbling to obtain a uniform distribution of the binder, the coated particles were removed from the blender and formed into a 24 inch by 28 inch by 1/2 inch panel in an electrically heated, hydraulically operated laboratory press. The press was maintained at a temperature of about 350F and a five-minute press cycle was used. Caul plates bound each side of the panel while it was being pressed. To prevent the panel from sticking to these plates, a 10% aqueous zinc stearate solution was sprayed on each plate. The resultant particleboards all had densities of 42 pounds per cubic foot.
The panels were then maintained at 72F, 65%
relative humidity until no change in weight was noted (this ge~erally took from 3 to 10 days). The panels were then tested using ASTM D-1037-72 to determine modulus of rupture (MOR), modulus of elasticity (MOE), tensile strength perpendicular to the surface (IB), 6-cycle MOR and wet MOR (MOR after a two-hour water boil and one-hour cold water soak). The results of such tests are as set forth in Table I.
Mo-2221 3'~
g 0 ~ J\ O O 1~ n ~1 ~ N ~ ~ ~ ~ N ~ N O CO
~1 ~ I` N ~ Ct~ _I N O il~ 0 O ~ O
m ~o u~o~~Or~oo~ o~u ct)~
o ~
o ~l ,~1 a~ ~o I
1~t o ~ o ~ co 1` ~ O ~I CO U~
O ~ ~ ~ ~ ~/ ~ ~ ~ ~1 ~D ~
O U~ ,1 ~ ~ r~ r~ l~ O O ~ ~ ~9 ~ O ~ ~ ~D OD ~ CO 1~ ~t ~ u~ a) H~ O . V~ ~ ~ L') ~ t-- O 0 1~'1 ~ ~ ~5 _ ~ ~ ~ ~ ~ ~ ~ ~ N ~ N ~ ) ~ ~ ~ N ~ N t~
Ir) O O L"l 1l ) 0 0 n ul 0 0 u~ O O u~ In O O u ) ~ 0 O u O .~ ~`1 O U l ~ ~ O ~ `1 N O l~r) N t~l O 11~ ~ N O L') t~ 1 O ~o N
~a ~1 O
O
h ~ U) ~ ~I) H
14 1~4 . O N ~D ~ L~ D ~ CD ~r r N CO ~ ~D N ~D CD r ~ O
n .......................
~U J~ ~D ~`J N ~1 ~-- ~r ~r Lr) _I CO 1` N a) Il ~ ~ 0 1` ~ 'D N a~ CO
~/ ~ 0~ _I N --1 N --1 ~I N --1 ~I N Ir1 .--1 N N ~ --1 N N ~) ,a ~a ~ ~8 _, J~
>~ D ~ m m m ~ a ~ a o U~
H
'a I ~-~ N tr~ D 1` CO ~ O ~--1 N ~ ~ 1~ ~ 1` 00 ~ O ~1 N (~) ~r ~ ~ ~1 _I ~ ~1 ~ ~ _I H ~I N ~ N N N
.,1 m The binder in this Example comprised a blend of 25 parts of Polyisocyanate D and 6 parts of benzaldehyde.
Three parts of the blend were mixed with 97 parts of wood chips as set forth in the previous Example. A
panel was produced as set forth in the previous Example.
The resultant panel had a specific gravity of 0.67, an IB of 111 psi, a MOR of 2500 psi and a wet MOR of 1866 psi.
The binder in these Examples comprised a blend of 25 parts of Polyisocyanate D and 6 parts of the aldehyde noted in Table II. Thirty-one parts of the blend were mixed with 1036 parts of wood chips as set forth in Example 1. Panels were produced as set forth in Example 1, with the exception that the press cycle was seven minutes instead of five minutes. The panels were tested for IB, MOR and wet MOR, with the results set forth in Table II being obtained.
TABLE II
IB MOR Wet MOR
Example Aldehyde (psi) (psi) (psi) 26 Cinnamaldehyde92 2366 1203 27 Salicyaldehyde90 2179 1089 28 Tolylaldehyde 110 2359 1209 29 Nonylaldehyde 99 2296 859 Butyraldehyde 72 1917 832 Mo-2221
Claims (8)
1. In a process for the production of panels from cellulosic particles comprising coating said cellulosic particles with a binder composition and thereafter compressing the coated cellulosic particles at an elevated temperature, the improvement wherein said binder composition comprises a mixture of a poly-isocyanate based on methylene di(phenylisocyanate) and an aldehyde which is soluble in said isocyanate and which is reactive therewith at a temperature of above 250°F.
2. The process of Claim 1, wherein said iso-cyanate is a polymethylene polyphenyl isocyanate.
3. The process of Claim 2, wherein said iso-cyanate is a mixture of isocyanate, said mixture having the following average formula:
wherein n has a value or from 0,5 to 4.
wherein n has a value or from 0,5 to 4.
4. The process of Claim 1, wherein said aldehyde is selected from the group consisting of furfural, benzaldehyde, cinnamaldehyde, nonylaldehyde, butyraldehyde, pelargonaldehyde, salicyaldehyde, chloro-benzaldehyde, ortho-tolylaldehyde, 2-naphthaldehyde, piperonal and vanillan.
5. The process of Claim 4, wherein said aldehyde is furfural.
6. The process of Claim 4, wherein said aldehyde is used in an amount of from 1 to 50 parts by weight per 100 parts by weight of the mixture of the aldehyde and isocyanate.
7. A composition comprising (a) a polyisocyanate based on methylene di(phenylisocyanate) and Mo-2221 (b) an aldehyde which is soluble in said isocyanate and which is reactive there-with at a temperature above 250°F.
8. A composition comprising (a) a polyisocyanate based on methylene di(phenylisocyanate), (b) an aldehyde which is soluble in said isocyanate and which is reactive there-with at a temperature above 250°F, and (c) cellulosic particles.
Mo-2Z21
Mo-2Z21
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US27368081A | 1981-06-15 | 1981-06-15 | |
| US273,680 | 1981-06-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1170394A true CA1170394A (en) | 1984-07-03 |
Family
ID=23044964
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000399801A Expired CA1170394A (en) | 1981-06-15 | 1982-03-30 | Production of structural panels using isocyanate/furfural binder |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0067426B1 (en) |
| JP (1) | JPS57210843A (en) |
| AT (1) | ATE18240T1 (en) |
| CA (1) | CA1170394A (en) |
| DE (1) | DE3269348D1 (en) |
| FI (1) | FI822100A0 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4436981A1 (en) * | 1994-10-06 | 1996-04-11 | Hartmut Faerber | Lightweight moulded thermal insulation made from renewable resources |
| US7071248B2 (en) | 2003-01-21 | 2006-07-04 | Ashland Licensing And Intellectual Property, Llc | Adhesive additives and adhesive compositions containing an adhesive additive |
| EP2805976A1 (en) * | 2013-05-24 | 2014-11-26 | Huntsman International Llc | Aldehyde comprising compositions suitable for making curable polyisocyanate compositions |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1351555A (en) * | 1972-09-05 | 1974-05-01 | Dow Chemical Co | Polyurethane foams |
| US3930110A (en) * | 1974-02-11 | 1975-12-30 | Ellingson Timber Co | Manufacture of multilayer panels using polyisocyanate: formaldehyde binder system |
| DE2711958B2 (en) * | 1977-03-18 | 1981-08-13 | Bayer Ag, 5090 Leverkusen | Binding or impregnating agent for lignocellulosic materials |
-
1982
- 1982-03-30 CA CA000399801A patent/CA1170394A/en not_active Expired
- 1982-06-11 DE DE8282105098T patent/DE3269348D1/en not_active Expired
- 1982-06-11 AT AT82105098T patent/ATE18240T1/en not_active IP Right Cessation
- 1982-06-11 FI FI822100A patent/FI822100A0/en not_active Application Discontinuation
- 1982-06-11 EP EP82105098A patent/EP0067426B1/en not_active Expired
- 1982-06-14 JP JP57100794A patent/JPS57210843A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| ATE18240T1 (en) | 1986-03-15 |
| JPS57210843A (en) | 1982-12-24 |
| DE3269348D1 (en) | 1986-04-03 |
| EP0067426A1 (en) | 1982-12-22 |
| FI822100A0 (en) | 1982-06-11 |
| EP0067426B1 (en) | 1986-02-26 |
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| MKEX | Expiry |