Classifications

• • 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

Definitions

• Composite materials such as oriented stand board, particle board and flake board are generally produced by blending or spraying lignocellulose materials such as wood flakes, wood fibers, wood particles, wood wafers, strips or strands, pieces of wood or other comminuted lignocellulose materials with a binder composition while the comminuted materials are blended by tumbling or agitating them in a blender or like apparatus. After blending sufficiently to form a uniform mixture, the materials are formed into a loose mat, which is compressed between heated platens or plates to set the binder and bond the flakes, strands, strips, pieces, etc. together in densified form.
• Isocyanate prepolymers are among the preferred isocyanate materials which have been used in binder compositions to solve various processing problems, particularly adhesion to press platens and high reactivity.
• U.S. Patent 4,100,328 discloses isocyanate- terminated prepolymers which improve product release from a mold.
• U.S. Patent 4,609,513 also discloses a process in which an isocyanate- terminated prepolymer binder is used to improve product release.
• a binder composition in which a particular type of isocyanate prepolymer is used to improve adhesiveness at room temperature is disclosed in U.S. Patent 5,179,143.
• This prepolymer is prepared by reacting (1 ) about 0.05 to about 0.5 hydroxyl equivalents of a polyol having a functionality of from 2 to 8 and a molecular weight of from about 62 to about 2000 with (2) one equivalent of a polyisocyanate mixture containing (a) from 0 to about 50% by weight of polyphenyl polymethylene polyisocyanate and (b) about 50 to about 100% by weight isomer mixture of diphenylmethane diisocyanate containing 10 to 75% by weight of 2,4'-isomer and 25 to 90% by weight of 4,4'-isomer.
• Pressing of wafer board, oriented strand board, and parallel strand lumber using steam injection and a conventional binder such as a urea- formaldehyde resin or a polymeric diphenylmethane diisocyanate (MDI) is known.
• a conventional binder such as a urea- formaldehyde resin or a polymeric diphenylmethane diisocyanate (MDI)
• MDI polymeric diphenylmethane diisocyanate
• This improved binder has the advantages that it uses less of the relatively expensive polyisocyanate to provide properties comparable to traditional MDI binders.
• the reactive amine containing extenders act as carriers for the liquid binder. These extenders do not contain additional water which can increase press cycle times. The tendency of the resin to adhere to the platens may also be reduced.
• the process comprises a) combining wood particles with (2) a polymethylene poly(phenyl isocyanate) having a functionality of about 2.1 to about 3.5, an NCO group content of from about 30 to 33%, and a monomer content of from about 30 to about 90% by weight, wherein the content of the monomer comprise up to about 5% by weight of the 2,2'-isomer, from about 1 to about 20% by weight of the 2,4'-isomer and from about 25% to about 65% by weight of the 4,4'-isomer, based on the entire weight of the polyisocyanate; b) coating the combination from a) with (1 ) a solid, dry compound selected from the group consisting of urea, melamine and mixtures thereof; and c) molding or compressing the coated combination formed in b).
• a polymethylene poly(phenyl isocyanate) having a functionality of about 2.1 to about 3.5, an NCO group content of from about 30 to 33%, and a monomer content of from about 30
• Suitable polyisocyanates to be used as component (2) of the compositions in the present invention include those polymethylene poly(phenylisocyanate) compositions and blends having a NCO group content of about 25% to 33% by weight, and having a viscosity of less than about 2,000 cps at 25 °C.
• the mixtures of solid amines and polyisocyanate have the consistency of a moist powder or that of brown sugar.
• the powdered binder formulations are applied to wood particles in the manufacture of particle board, wafer board, fiber board, etc., by intermixing a stream of wood particles with a stream of the powdered binder formulation at the desired ratio and using mechanical agitation which is in common usage in the manufacture of composite products such as particle board.
• the wood may have a wide range of moisture content, i.e., from about 0.5 to about 10% by weight, based on the total weight of the wood particles.
• Suitable solid, dry compounds to be used as component (1 ) of the present invention include urea, melamine, and mixtures thereof.
• the dry, solid urea, melamine and mixtures thereof contain, for the purposes of this invention, less than 10% by weight of water, and are preferably in the absence of water.
• similar compounds including, but not limited to guanidine or dicyanodiamide can be used, but they are preferably added as mixtures with urea and/or melamine due to their disadvantageous tendency to release ammonia.
• dry means that there is less than 10% by weight of entrained water in the solid.
• the formulation for a particular product will depend upon wood species, requirements of physical properties of the resultant product, and pressing conditions, For example, a formulation range for Douglas fir commercial furnish requirements for interior particle board pressed at a press platten temperature of 350°F for 4.4 minutes press time, to give a high quality commercial product is as follows:
• This binder formulation may be used in an amount of 1 to 25% by weight, expressed as a percentage of the total wood weight, or about 0.25 to 8.0% of PMDI based on the wood weight.
• the quantity of binder formulation based on the weight of the wood is about 2 to 10%, depending on the configuration of the particulate wood and the requirements of the products.
• relatively greater proportions of binder formulation will be used (e.g., 8 to 10% binder formulation, or 1 to 2% isocyanate based on the wood weight).
• Sebacic Acid This substance was purchased from Aldrich Chemical Company, ground using a mortar and pestle, and sieved through a #45 US-mesh sieve. In all cases (with the exception of example 6) for the purpose of this invention, sebacic acid is added at 0.5 weight percent based on the total weight (wood + binder) of every individual formulation.
• Isocyanate A Two parts were combined with one part Sebacic acid in a 32-oz. jar and mixed well. One and one half parts Isocyanate A/Sebacic acid were added to seven parts Melamine. Burundum cylinders were added to the 32-oz. jar, which was then rolled in a roller table for 1 to 1.5 hours. The container was periodically opened, and material clinging to the container walls was scraped off. The binder mix was then sieved through a #45 US-mesh sieve and placed in a catch pan. The catch pan containing the binder was placed in a dessicator for 3 to 4 hours. Procedure for Preparation of Isocyanate A/Urea Binder

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)
• Polyurethanes Or Polyureas (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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Applications Claiming Priority (2)

Publications (1)

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Citations (3)

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• 1998
  • 1998-12-17 US US09/213,606 patent/US6224800B1/en not_active Expired - Lifetime
• 1999
  • 1999-12-10 AU AU31184/00A patent/AU748481B2/en not_active Ceased
  • 1999-12-10 EP EP99965219A patent/EP1141134B1/en not_active Expired - Lifetime
  • 1999-12-10 PL PL99349316A patent/PL349316A1/xx unknown
  • 1999-12-10 NZ NZ512386A patent/NZ512386A/xx unknown
  • 1999-12-10 WO PCT/US1999/029360 patent/WO2000036020A1/en not_active Ceased
  • 1999-12-10 BR BR9916219-9A patent/BR9916219A/pt not_active Application Discontinuation
  • 1999-12-10 AT AT99965219T patent/ATE262565T1/de not_active IP Right Cessation
  • 1999-12-10 CN CN99814493A patent/CN1124319C/zh not_active Expired - Fee Related
  • 1999-12-10 JP JP2000588274A patent/JP2002532293A/ja not_active Withdrawn
  • 1999-12-10 CA CA002354602A patent/CA2354602C/en not_active Expired - Fee Related
  • 1999-12-10 HK HK02104728.9A patent/HK1042917B/zh not_active IP Right Cessation
  • 1999-12-10 DE DE69915879T patent/DE69915879T2/de not_active Expired - Lifetime
  • 1999-12-10 ES ES99965219T patent/ES2217870T3/es not_active Expired - Lifetime

Patent Citations (3)

Non-Patent Citations (2)

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