United States Patent (19)
`Hsu et al.
`
`||||||||||||
`US005616419A
`11
`Patent Number:
`5,616,419
`45). Date of Patent:
`Apr. 1, 1997
`
`w
`
`a.
`
`y
`
`CCIS .......
`
`-
`
`
`
`3/1988 Morita et al. .......................... 264/45.3
`4,734,231
`(54) METHOD OF PRODUCING COATING ON
`4,814,373 3/1989 Frankel et al.....
`... 524/460
`RECONSTITUTED WOOD SUBSTRATE
`4,966,170 10/1990 Keritsis et al. ...
`... 13/88
`2: &E. Spen
`(75) Inventors: Oscar Hsien-Hsiang Hsu, Lansdale,
`- E.
`Sé E. S.ESE 5,063,646 11/1991 Zeiffer et al. .
`... 28/167
`- Y - 9
`p i.
`Oil,
`5,085,891
`2/1992 Evans ................
`... 427/277
`436,06
`73) Assignees: Rohm and Haas Company,
`5.436,069 7/1995 Winterowd etal
`428/308.8
`FOREIGN PATENT DOCUMENTS
`Philadelphia, Pa.; Akzo Nobel Inc.,
`Louisville, Ky.
`2021777
`1991 Canada.
`1653244 4/1972 Germany.
`21 Appl. No.: 635,134
`9081510 8/1974 Japan.
`la-
`2096636 8/1977 Japan.
`22) Filed:
`Apr. 19, 1996
`8020435 2/1983 Japan
`3136806 6/1991 Japan.
`Related U.S. Application Data
`3267174 11/1991 Japan.
`5117629 5/1993 Japan.
`62) Division of Ser. No. 474,034, Jun. 7, 1995.
`1387484 3/1975 United Kingdom.
`(51) Int. Cl. ............................... B32B 21/02
`9315888 8/1993 WIPO :
`52 U.S. Cl. ........................... 428/512; 428/513; 428/514
`OTHER PUBLICATIONS
`58) Field of Search ..................................... 428/511, 512,
`The Characterization of Polymers, Ch. 1 (published by
`28/513, 54 Rohm and Haas Company, Philadelphia, PA, 1976).
`Primary Examiner Michael Lusignan
`Assistant Examiner-Erma Cameron
`Attorney, Agent, or Firm-Sudhir G. Deshmukh; Loretta A.
`Miraglia
`ABSTRACT
`(57)
`The present invention is directed to producing a smooth hard
`coating on a wood substrate. A layer of a foamed polymer
`-
`ized latex emulsion is applied on the surface of a wood
`substrate, such as an oriented strand board. The layer is
`dried, crushed and then cured to form the orating. If desired
`the cured coating may be provided with a post cure heat
`treatment to improve its hardness. The present invention is
`also directed to applying and drying the layer of the foamed
`polymerized latex emulsion on amat of wood fibers or flakes
`and then crushing and curing the crushed layer and the mat
`into a hardboard having a smooth hard coating. The coating
`of the present invention is useful as a sealer coat on a wood
`bstrate. By addi
`tt
`l
`ized
`lsi
`th
`substrate. By adding pigment topolymerized emulsion, the
`sealer coat can be used to provide a finish coat on the wood
`substrate.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`3,098,785 7/1963 Meiler ....................................... 162/11
`3,607,341
`9/1971 Goins et al. .............................. 117/10
`3,790,421 2/1974 Habgood, Jr. .
`... 156/242
`3,804,700 4/1974 Hoey .........
`169
`3,901,240 8/1975 Hoey .........
`... 128/296
`3,919,451 11/1975 Levy et al.....
`... 428/310
`3,933,691
`1/1976 Lindemann ...
`260/2.5 L
`3,957.940 51976 Schubert et al...
`264/171
`3661.11s 6/1976 Michaelis.
`... as?isi
`4,061,822 12/1977 Brodnyan et al. ...
`428/315
`4,238,438 12/1980 Laughinghouse et al.
`... 264/119
`4,265,965 5/1981 Chancier ..................
`... 428/315
`4,289,823 9/1981 Arkens.
`... 428/245
`4,325,856 4/1982 Ishikawa ...
`... 52320
`35 3. E. SR bend
`5.
`saw w
`Ollac ...
`4,385,152 5/1983 Boyack et al. .......................... 524/460
`4,403,003 9/1983 Backhouse .......
`240
`4,510,268 4/1985 Tonokawa et al. ..................... 521/146
`4,517,228 5/1985 Matejka et al. ......................... 427/370
`4,654,397 3/1987 Mall et al. ...
`... 524/460
`4,692,473 9/1987 Wright et al.............................. 521/72
`
`7 Claims, No Drawings
`
`Louisiana-Pacific Corporation, Exhibit 1026
`IPR of U.S. Pat. No. 8,474,197
`Page 1
`
`

`

`1.
`METHOD OF PRODUCING COATING ON
`RECONSTITUTED WOOD SUBSTRATE
`
`5,616,419
`
`10
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`15
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`drying the foamed layer into a hardened layer;
`crushing the hardened layer; and
`curing the crushed layer to form the coating on the wood
`substrate.
`The present invention is also directed to a method of
`producing a coated reconstituted wood substrate compris
`ing:
`mixing a binder with wood particles, chips, fibers or
`flakes to form a wood/binder mix;
`dispensing the wood/binder mix on a conveying surface to
`produce a mat;
`foaming a polymerized latex emulsion comprising poly
`mer particles of a polymer of an ethylenically unsat
`urated monomer, the polymer having T in the range of
`10°C. to 100°C., a foaming agent and a foam stabilizer
`in the range of 0 to 15 percent by weight of the
`emulsion solids;
`applying a foamed layer of the foamed polymerized latex
`emulsion on the surface of the mat,
`drying the foamed layer into a hardened layer;
`crushing the hardened layer; and
`curing the crushed layer and the mat into the coated
`reconstituted wood substrate.
`The present invention is further directed to a polymerized
`latex emulsion suitable for producing a smooth hard coating
`on the surface or edge of a reconstituted wood substrate
`comprising: from 10 percent to 60 percent by weight of the
`emulsion solids of polymer particles of a polymer of an
`ethylenically unsaturated monomer, the polymer having T.
`in the range of 10° C. to 100° C., a foaming agent, and from
`0 percent to 15 percent by weight of the emulsion solids of
`a foam stabilizer selected from the group consisting of
`disodium N-octadecylsulfosuccinate, tetrasodium N-(1,2-
`dicarboxyethyl)-N-octadecylsulfosuccinate,
`sulfosuccini
`mate surfactant, diamyl ester of sodium sulfosuccinic acid,
`dihexyl ester of sodium sulfosuccinic acid, dioctyl ester of
`sodium sulfosuccinic acid, distearyl pyridinium chloride,
`N-coco-beta-aminopropionic acid and the sodium salts
`thereof.
`The present invention is further directed to RWS surface
`coated in accordance with the method of the present inven
`tion.
`The present invention is further directed to a coating on
`the surface of RWS.
`The coatings produced by the processes of the present
`invention are smooth and hardened and they are substan
`tially free from cracks, voids and porosity. It is contemplated
`that smooth and hard coatings may be provided with a
`texture or may be applied over shaped or molded RWS.
`As used herein:
`"Surface or Surfaces' include any exposed surface, edge
`or edged surface of RWS.
`"Polymerized latex emulsion” means an aqueous colloi
`dal dispersion of polymer particles.
`"Emulsion solids' means weight of the polymer particles
`in their dry state.
`"Medium density fiberboard” means a board manufac
`tured from lignocellulosic fibers bonded under heat and
`pressure by means of a well dispersed synthetic resin or
`a similar binder. Such a board is manufactured to a
`specific gravity of 0.50 to 0.88.
`"Oriented strand board (OSB)' means a board manufac
`tured from lignocellulosic strand-type flakes purpose
`fully aligned in a direction that makes the resultant
`board stronger, stiffer and having improved dimen
`
`This is a divisional of application Ser. No. 08/474,034,
`filed Jun. 7, 1995.
`This invention generally relates to a method of producing
`coated wood substrates and more particularly to producing
`reconstituted wood substrates having a sealer coating
`thereon.
`Reconstituted wood substrate (RWS) means, substrates
`produced from wood particles, fibers, flakes or chips, such
`as, a hardboard, a medium density fiberboard, an oriented
`strand board also known as wafer board, a flake board, a
`chipboard and a particleboard. Such a RWS is typically
`fabricated under heat and pressure from particles, fibers,
`flakes or chips. RWS is produced by treating particles,
`flakes, chips or fibers with a binder and then arranging these
`treated particles, flakes, chips or fibers in the form of a mat
`under dry or wet conditions. The mat is then compressed into
`a dense substrate, typically in a sheet form, by the applica
`tion of heat and pressure. The binder binds particles, flakes,
`chips or fibers and enhances the structural strength and
`integrity of the RWS and its water resistance. The RWS, if
`desired, may be molded into desired shape or provided with
`a textured surface, such as, wood grain texture.
`Reconstituted wood substrates tend to have rough and
`sometimes pitted uneven surfaces. Secondary operations,
`such as, cementing paper overlays or applying multilayer
`coatings on such rough surfaces have been attempted. How
`ever, such paper overlays or multilayer coatings still tend to
`be uneven. The present invention solves these problems by
`providing a process that produces smooth hard coating
`adhered to RWS.
`One of the methods for producing a foamed, dried,
`crushed and cured layer of a latex composition has been
`described by Goins in U.S. Pat. No. 3,607,341. Goins
`discloses a method for producing a soft, pliable crushed
`foam backing on textile fabrics by foaming, applying, dry
`ing, crushing and curing a layer of a latex composition
`consisting essentially of water, ethylenically unsaturated
`monomers and a water soluble organic surfactant on the
`40
`surface of a textile fabric to produce a backing having a
`density of 30 to 65 pounds per cubic feet (0.48 to 1.04 grams
`per milliliters). One of the problems associated with such a
`method is that the resultant soft coating is unsuitable as a
`coating on the surface of a RWS. The present invention
`solves this problem by producing smooth hard coating
`adhered to RWS.
`Another problem associated with RWS is that its surfaces
`tend to have different degrees of absorbency, which it is
`believed, without reliance thereon, to result from the varia
`tion in RWS density across the RWS surface. It is believed
`that such a density variation results during the manufacture
`of RWS or is due to variations typically present in the quality
`of wood chips, particles, flakes or fibers used in producing
`RWS. As a result, such RWS when coated with a sealer
`coating tends to be blotchy. The method of the present
`invention solves this problem by producing smooth hard
`coating adhere d to RWS that is free from blotches.
`The present invention is directed to a method of produc
`ing a coating on the surface of a reconstituted wood substrate
`comprising:
`foaming a polymerized latex emulsion comprising poly
`mer particles of a polymer of an ethylenically unsat
`urated monomer, the polymer having T in the range of
`10° C. to 100° C., and a foaming agent;
`applying a layer of the foamed polymerized latex emul
`sion on the surface of the substrate;
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`Louisiana-Pacific Corporation, Exhibit 1026
`IPR of U.S. Pat. No. 8,474,197
`Page 2
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`5,616,419
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`sional properties in the direction of alignment when
`compared to a board having random flake orientation.
`OSB is also known as wafer board.
`"Particle board' means aboard manufactured from wood
`particles bonded under heat and pressure by means of
`a well dispersed synthetic resin or similar binder. Such
`a board includes conventional extruded and mat
`formed particle boards.
`"Flake board' means a board manufactured from wood
`flakes bonded under heat and pressure by means of a
`well dispersed synthetic resin or similar binder.
`"Plywood' means a glued wood panel made up of rela
`tively thin layers of veneer with the grain of adjacent
`layers at right angles or a panel made up of veneer in
`combination with a core of lumber or of RWS.
`“Underlayment' means a smooth flat RWS used as a floor
`panel upon which resilient floor covering may be glued.
`"Add-on' means grams of the solid portion of a polymer
`ized latex emulsion (dry portion) coated over a meter
`square area of the surface of the substrate.
`“B” stage curing means partial curing of a polymerized
`latex emulsion.
`The basic process for the preparation of RWS from wood
`chips, flakes, particles or fibers is known in the art. (gener
`ally, this process is disclosed in U.S. Pat. Nos. 3,098,785 and
`4,238,438.
`The first step of the first embodiment of the present
`invention directed to producing a coating on the surface of
`a RWS comprises foaming a polymerized latex emulsion
`having afoam density in the range of 0.04 to 0.25, preferably
`from 0.06 to 0.15 grams per milliliters. The foam density is
`controlled by adjusting the ratio of the polymerized latex
`emulsion to a non-reacting gaseous foam conveying
`medium, such as air, nitrogen, helium or carbon dioxide. Air
`is preferred. The foamed polymerized latex emulsion is
`provided with a viscosity in the range of 25 to 1200
`centipoise (cps), preferably in the range of 50 to 800 cps.
`The viscosity is controlled by adjusting the amount of water
`present in the polymerized latex emulsion, by addition of
`suitable rheology modifiers, such as, RM-8256) rheology
`modifier supplied by Rohm and Haas Company, Philadel
`phia, Pa. or by doing both. Viscosities in excess of the upper
`limit of 1200 cps, are difficult to foam and those with
`viscosities less than 25 cps are difficult to maintain in a
`foamed state.
`Conventional foaming devices, such as, the Texacote
`Foamer, supplied by Textile Rubber and Chemical Co.,
`Dalton, Ga. are suitable since such devices utilize air or gas
`whipping action to produce a foam of fine uniform bubble
`structure. Suitable gases include nonreactive gases, such as,
`carbon dioxide and nitrogen. Foam produced by air whip
`ping is preferred. The foaming step is preferably carried out
`at room temperature.
`The polymerized latex emulsion used in the foaming step
`of the first embodiment includes from 10 percent to 60
`percent, preferably from 20 percent to 50 percent and most
`preferably from 35 percent to 45 percent of polymer par
`ticles, all percentages being in weight percentages based on
`the total weight of the emulsion.
`The polymer particles have a particle size in the range of
`50 to 500 nanometers, preferably in the range of 70 to 250
`Ilanlonieters.
`The polymer particles are produced from latex polymers
`having a glass transition temperature (T) in the range of 10°
`C. to 100 C. (as measured at mid-point range using con
`ventional differential scanning calorimetry), preferably in
`
`4
`the range of 20° C. to 60° C. Such polymers are preferably
`copolymers of at least one ethylenically unsaturated mono
`mer, such as, for example, acrylic ester monomers including
`methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl
`acrylate, decyl acrylate, methyl methacrylate, butyl meth
`acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate,
`isodecyl (meth)acrylate, oleyl (meth)acrylate, palmityl
`(meth)acrylate, stearyl (meth)acrylate, hydroxymethyl
`(meth)acrylate, hydroxyethyl (meth)acrylate, and hydrox
`ypropyl (meth)acrylate; acrylamide or substituted acryla
`mides; styrene or substituted styrenes; butadiene; vinyl
`acetate or other vinyl esters; vinyl monomers, such as, for
`example, vinyl chloride, vinylidene chloride, N-vinyl pyr
`rolidone; amino monomers, such as, for example, N,N'-
`dimethylamino (meth)acrylate; and acrylonitrile or meth
`acrylonitrile. Additionally copolymerizable ethylenically
`unsaturated acid monomers in the range of, for example,
`front 0.1 percent to 7 percent, by weight based on the weight
`of the emulsion-polymerized polymer, acrylic acid, meth
`acrylic acid, crotonic acid, itaconic acid, fumaric acid,
`maleic acid, monomethyl itaconate, monomethyl fumarate,
`monobutyl fumarate, maleic anhydride, 2-acrylamido-2-me
`thyl-1propanesulfonic acid, sodium vinyl sulfonate, and
`phosphoethyl methacrylate, may be used.
`The polymer used in this invention can be a substantially
`thermoplastic or substantially uncrosslinked polymer when
`applied to the substrate. If desired, premature crosslinking or
`gelling of the polymer is induced by adding to the monomer
`mix multi-ethylenically unsaturated monomers in the range
`of 0.01% to 5%, by weight based on the weight of the
`polymer. Typical multi-ethylenically unsaturated monomers
`include allyl methacrylate, trimethylolpropane triacrylate,
`diallyl phthalate, 1,4-butylene glycol dimethacrylate, 1,6-
`hexanedioldiacrylate and divinyl benzene. It is important,
`however, that the quality of the film formation is not
`materially impaired.
`The sealer coating produced from latex polymers having
`the T in range of 10° C. to 100° C. are hard with substan
`tially no regain in the thickness of the coating applied over
`RWS.
`The polymerization techniques used to prepare such latex
`polymer particles are well known in the art. The polymer
`particles are preferably prepared by emulsion polymeriza
`tion.
`The polymerization process is typically initiated by con
`ventional free radical initiators, such as, for example, hydro
`gen peroxide, benzoyl peroxide, t-butyl hydroperoxide, t-bu
`tyl peroctoate, ammonium and alkali persulfates, typically at
`a level of 0.05% to 3.0% by weight, based on the weight of
`total monomer, may be used.
`Chain transfer agents, such as, for example, mercaptans
`may be used in an amount effective to provide a GPC weight
`average molecular weight of 10,000 to 1,000,000. "GPC
`weight average molecular weight' means the weight average
`molecular weight determined by gel permeation chromatog
`raphy (GPC) described on page 4, Chapter I of The Char
`acterization of Polymers published by Rohm and Haas
`Company, Philadelphia, Pa. in 1976, utilizing polymethyl
`methacrylate as the standard.
`The size of the polymer particles is controlled by the
`amount of conventional surfactants added during the poly
`merization process. It is known in the art that by increasing
`the amount of surfactant added during polymerization, the
`diameter of the polymer particles can be reduced and by
`reducing the amount of Surfactant, one can increase the
`diameter of the polymer particles. Conventional surfactants
`include anionic, nonionic emulsifiers or their combination.
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`Louisiana-Pacific Corporation, Exhibit 1026
`IPR of U.S. Pat. No. 8,474,197
`Page 3
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`S
`Anionic emulsifier is preferred. Typical anionic emulsifiers
`include alkali or ammonium alkyl sulfates, alkyl sulfonic
`acids, fatty acids, and oxyethylated alkyl phenols. Sodium
`lauryl sulfate is preferred. Typical nonionic emulsifiers
`include polyoxyethylenated alkylphenols, alkylphenol
`ethoxylates, polyoxyethylenated straight-chain alcohol,
`amine polyglycol condensate, modified polyethoxy adducts,
`long chain carboxylic acid esters, modified terminated alky
`laryl ether, and alkylpolyether alcohols.
`Alternatively, the polymer particles include multi-stage
`latex polymers provided with two or more phases of various
`geometric structures, such as, for example, core/shell or
`core/sheath particles, core/shell particles with shell phases
`incompletely encapsulating the core, core/shell particles
`with a multiplicity of cores and interpenetrating network
`particles. In all of these cases the majority of the surface area
`of the particle will be occupied by at least one outer phase
`and the interior of the latex polymer particle will be occu
`pied by at least one inner phase. The outer phase of the
`multi-stage polymer particles weighs 5 percent to 95 per
`cent, by weight based on the total weight of the particle and
`is preferably softer than the inner phase.
`The multi-stage polymer particles are prepared preferably
`by a conventional emulsion polymerization process in which
`at least two stages differing in composition are formed in a
`sequential fashion. Such a process usually results in the
`formation of at least two mutually incompatible polymer
`compositions, thereby resulting in the formation of at least
`two phases. Each of the stages of the multi-stage polymer
`particles may contain the same monomers, chain transfer
`agents, surfactants, as those disclosed earlier for the polymer
`particles. The emulsion polymerization techniques used for
`preparing such multi-stage polymer particles are well known
`in the art and are disclosed, for example, in the U.S. Pat.
`Nos. 4,325,856, 4,654,397 and 4,814,373.
`The polymerized latex emulsion further contains from 1
`to 15 percent, preferably from 5 to 10 percent, by weight of
`the emulsion solids of a foaming agent. Some of the suitable
`foaming agents include alkali metal, ammonium and amine
`salts offatty acids, such as, aliphatic or mixtures of aliphatic
`carboxylic acids, or the mixtures thereof. Examples of
`preferred aliphatic carboxylic acids include stearic acid,
`tallow fatty acids and oleic acid. Particularly preferred are
`salts or soaps of stearic acid or of partially or fully hydro
`genated fatty acids of natural origin containing stearic acid,
`such as, hydrogenated tallow acid, hydrogenated tall oil fatty
`acids, hydrogenated soybean oil fatty acids, and hydroge
`nated tung acids. More preferred water-soluble salts or soaps
`of these acids are the alkali metal, usually sodium or
`potassium salt, the ammonium salts and the amine salts,
`such as, alkanolamine salts, e.g., mono-, di- and triethano
`lamine salts. Ammonium stearate is most preferred.
`The polymerized latex emulsion further contains from 0
`to 15 percent, preferably front 0.1 to 15 percent, more
`preferably 5 to 7 percent, by weight of the emulsion solids
`of a foam stabilizer. Suitable foam stabilizers include
`anionic and nonionic surfactants, such as, sulfosuccinate
`ester salts, such as, disodium N-octadecylsulfosuccinate,
`tetrasodium N-(1,2-dicarboxyethyl)-N-octadecylsulfosucci
`nate, sulfosuccinimate surfactant diamyl ester of sodium
`sulfosuccinic acid, dihexyl ester of sodium sulfosuccinic
`acid, dioctyl ester of sodium sulfosuccinic acid. Additional
`foam stabilizers include cationic or an amphoteric surfac
`tants, such as, distearyl pyridinium chloride, N-coco-beta
`aminopropionic acid or the sodium salts thereof. Calcium
`succinimate is preferred.
`If desired, the foam stability of the foamed layer may be
`achieved by increasing the T of a latex polymer without the
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`6
`addition of the foam stabilizer in the polymerized latex
`emulsion. If the amount of either the foaming agent or the
`stabilizer added to the emulsion exceeds 15 percent by
`weight of the emulsion, the water sensitivity of the resultant
`coating is adversely affected.
`The polymerized latex emulsion optionally includes from
`0 to 40 percent, preferably from 0.5 to 40 percent, more
`preferably from 10 to 20 percent, by weight of the emulsion
`solids of a crosslinking agent. Some of the suitable cross
`linking agents include polyisocyanate cross linkers, such as,
`toluene diisocyanate, diphenylmethane diisocyanate; carbo
`diimide cross linkers; epoxy resins, such as those obtained
`from bis-phenol A and epichlorohydrin; organic peroxides,
`such as, benzoyl peroxide; aminoplast resins containing a
`nucleus or nuclei of acetoguanamine, benzoguanamine, adi
`poguanamine, or preferably of melamine. Some of the
`suitable aminoplast resins include methylol urea,
`dimethoxymethylol urea, butylated polymeric urea-formal
`dehyde resins, hexamethoxymethyhnelamine, methylated
`polymeric melamine formaldehyde resin, glycouril and dim
`ethylol-dihydroxyl ethylene urea. Hexamethoxymeth
`ylmelamine is preferred. The aminoplast resin is considered
`to be fully alkylated, or substantially completely methy
`lolated and subsequently substantially fully etherified with
`alcohol, with the number of alkyloxymethyl groups ranging
`from 2n-2 to 2n where n is the number of amino groups on
`the triazine ring. The preferred degree of polymerization of
`this aminoplast is front 1 to 3. The amount of cross linking
`agent added to the polymerized latex emulsion depends
`upon the degree of hardness and cross linking density
`desired in a resultant coating. It has been discovered that the
`presence of the crosslinking agent in the polymerized latex
`emulsion improves toughness of the resultant coating. How
`ever, adding in excess of 40 percent of the cross linking
`agent is not recommended since it results in poor adhesion,
`blistering and instability of the resultant coating on the RWS
`substrate surface.
`If desired, the polymerized latex emulsion further
`includes from 0 to 10 percent, preferably from 1 to 5 percent,
`by weight of the emulsion solids of a wetting agent, such as,
`for example, C2 to C1s primary, secondary and tertiary
`amines and salts thereof, diamines, polyamines and their
`salts, quaternary ammonium salts, polyoxyethylenate
`amines, quaternized polyoxyethylenate amines or amine
`oxides. The purpose of the wetting agent is to enhance the
`surface wetting of the underlying substrate, especially for
`difficult to wet surfaces, such as, greasy, dirty or waxy
`surfaces. The wetting agent allows uniform and substantially
`complete contacting of the foamed layer to the underlying
`RWS surface.
`If desired, the polymerized latex emulsion further
`includes from 0.1 to 2 percent, preferably from 0.2 to 0.8
`percent, by weight of the emulsion solids of a homogenizing
`agent. Suitable homogenizing agents include non-ionic sur
`factants, such as, preferably, TRITONGR) X-405 octyl phe
`noxy polyethoxy ethanol supplied by Union Carbide Co.,
`Charleston, W.Va. The purpose of the homogenizing agentis
`to enhance the uniform and homogeneous dispersion of the
`various components of the polymerized latex emulsion,
`especially for attaining uniform color dispersion of a pig
`mented polymerized latex emulsion.
`Depending upon the intended use of the coating, addi
`tional components may be added to the polymerized latex
`emulsion. These additional components include but are not
`limited to pigments; pigment extenders; plasticizers; cosol
`vents; rheology modifiers; fillers, such as, talc; preservatives
`and freeze/thaw protectors. More particularly preferred filler
`
`Louisiana-Pacific Corporation, Exhibit 1026
`IPR of U.S. Pat. No. 8,474,197
`Page 4
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`5,616,419
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`is talc in platelet form, such as that described in U.S. Pat. No.
`4,517,228.
`The next step of the first method of the present invention
`is directed to applying a layer of a desired thickness of the
`foamed latex emulsion on the surface or edge of a RWS by
`conventional means, such as, a curtain coater, spray nozzle,
`roller coater, flow coater or by extrusion, which is particu
`larly useful for coating edges. The foamed layer may be
`leveled to a desired thickness by such conventional means as
`a doctor blade to meet the desired requirements of the
`resultant coating, such as a sealer coating. Foamed layer in
`the range of 0.8 mm to 10 mm, preferably in the range of 2
`to 5 mm is desirable. The present invention contemplates
`applying the foamed layer on more than one side of the
`RWS, such as, front and back or along the edges of a
`substantially planar RWS or on the surface of a contoured
`RWS, such as, a molding or molded door panel. It is further
`contemplated that the foamed layer is applied on a continu
`ously moving RWS or on a precut RWS as part of a batch
`operation.
`The foamed latex layer is then dried into a hardened
`foamed layer by reducing the moisture content of the
`foamed latex layer in the range of 0 to 20 percent by weight
`of the emulsion solids. The "hardened layer” means a
`foamed layer that does not collapse by itself and feels rigid
`to digital pressure. Conventional drying methods, such as,
`preferably by conveying dry heated air over the foamed
`layer, or by subjecting the foamed layer to infrared heating,
`are suitable. An applicable drying temperature and drying
`time is suitably adjusted for the polymerized latex emulsion
`being used and the thickness of the applied layer. The
`applicable drying temperature typically varies from 40° C.
`to 180° C. However, if desired, drying may be conducted at
`ambient temperatures. The drying time is correspondingly
`reduced for higher applicable drying temperatures and
`extended for lower applicable drying temperatures. For
`example, the foamed layer is dried for a duration varying
`from 6 hours to 30 seconds, preferably from 5 to 10 minutes
`at 121 C. or from 2 to 4 minutes at 150° C. Conventional
`drying means, such as, a convection air drying oven or a
`conveyer belt passing through a tunnel heated by infrared
`lights, are suitable.
`The dry hardened foamed layer on the surface of the RWS
`is then crushed at an applicable crushing pressure suitable
`for the polymerized latex emulsion being used. Conven
`tional crushing means, such as, pneumatically or hydrauli
`cally pressurized platens, or by squeezing the RWS through,
`a pair of nip rollers, series of nip rollers or a pair of parallely
`positioned conveyer belts, may be utilized to uniformly
`crush the dry hardened foamed layer. The applicable crush
`ing pressure should be sufficient to substantially crush the
`hardened foamed layer, which is typically in the range of 0.1
`to 3.5 Newton per square millimeters (N/mm), preferably in
`the range of 0.14 to 2.0 N/mm’. Optionally the crushing step
`is simultaneously conducted under an applicable crushing
`temperature suitable for the polymerized latex emulsion
`being used. The applicable crushing temperature generally
`varies front 24° C. to 287 C., preferably from 150° C. to
`240 C. If desired, the crushing step may be conducted under
`freezing conditions, such as, for example, by freezing the
`dry hardened foamed layer by exposing it to liquid carbon
`dioxide.
`The crushed layer is then cured for an applicable cure time
`at an applicable cure temperature suitable for the polymer
`ized latex emulsion being used. The applicable cure tem
`perature and time are adjusted to prevent thermal decom
`position of the resultant coating or sticking of the coating to
`
`8
`the press platens. The applicable cure temperature typically
`varies from 24° C. to 287 C., preferably from 177° C. to
`232° C., and the applicable cure time varies from 120
`minutes to 1 to 5 seconds, preferably front 30 minutes to 1
`minute. The cure step is conducted preferably simulta
`neously under an applicable cure pressure suitable for the
`polymerized latex emulsion being used. The applicable cure
`pressure varies from 0.1N/mm to 3.5N/mm', preferably
`from 0.14N/mm to 2.0N/mm. Conventional hot pressing
`means, such as, a molding press having pneumatically or
`hydraulically pressurized heated platens is suitable for a
`batch operation and conventional hot pressing means, such
`as, a pair of heated calendar rolls, series of heated calendar
`rolls, a pair of parallely positioned heated conveyer belts, or
`UV curing lights, may be used for a continuous operation by
`squeezing the RWS therethrough. The molding press is
`preferred. If desired the crushing and curing steps may be
`conducted simultaneously.
`The method of the present invention also contemplates
`curing the crushed layer in gradually increasing or in dis
`cretely increasing stages, i.e., the crushed layer is a "B"
`stage cured at a “B” stage cure temperature suitable for the
`polymerized latex emulsion being used and then fully cured
`at the cure temperature. It is believed, without reliance
`thereon, that by curing the crushed layer in stages, the
`resultant coating is provided with more flexibility.
`The method of the present invention alternatively con
`templates curing the crushed layer in gradually increasing or
`in discreetly increasing stages, i.e., the crushed layer is 'B'
`stage cured at a “B” stage cure temperature and pressure
`suitable for the polymerized latex emulsion being used and
`then fully cured at the cure temperature and pressure.
`The first step of the second embodiment of the present
`invention directed to producing a coating on the surface of
`a RWS comprises mixing a binder with a lignocellulosic
`material in the form of wood fibers, flakes, particles, or chips
`to form a wood/binder mix. Flakes are preferred. The
`lignocellulosic material is thoroughly mixed, by conven
`tional mixing means, such as, a tumble mixer, with from 1
`to 10 percent, preferably from 2 to 5 percent, by weight of
`the lignocellulosic material of the binder. Some of the
`suitable binders include melamine formaldehyde resin, phe
`nol-formaldehyde resin, urea-formaldehyde resin, isocyan
`ate binders, such as, diphenylmethane diisocyanate; and
`waxes for improved water repellency of a resulting sub
`Strate.
`The next step of the method of the second embodiment of
`the present invention includes dispensing the wood/binder
`mix on a conveying surface, such as, a conveyerbelt, to form
`a mat, which typically varies from 6.4 mms to 200 mms in
`thickness. The wood/binder mix is entrained in air, such as
`an air blower, transported and then dispersed on