FIELD OF THE DISCLOSURE

fCMME] The present disclosure relates to a putty composition and wood substrates having surface defects treated with ihe putty composition ·· the putty composition having, inter alia, enhanced iroughabilsty and final aesthetic characteristics.

BACKGROUND

|0®©2] Currently, defects in cellulosic subst ates are repaired by manually filling the defect with a water-based curable composition. The present invention provides a composition and method for rapidly curing wood putty utilizing a combination of UV radical polymerization and thermal initiators, Previous methods require thioi-ene type chemistry that leads to noticeable odors and requires significant energy and time for full cure. In applications using water-based putty, the composition is allowed to air dry over a period of six to twenty-four hours that now removes goods in progress from being completed on-fine. This now creates costly inventory and more labor required to remove puttied wood from line, stack down, and then when dry, pkce back onto line for completion of process. The use of water-based putty compositions also results inconsistent properties due to changes in environment, e.g. temperature and humidity that leads to defects when curing over the extended period of time. Slumping of the putty or excess shrinkage can occur when drying.

[0 )031 Thus, there remains a need for compositions suitable for use in an instant cure putty composition that can be used on wood products to allow for continuous flow through the process without interruption, Embodiments of the present invention are directed to meeting these needs.

SUMMARY

[0004] In some embodiments, the present invention provides a composite panel comprising a first major surface opposite a second major surface, the composite panel further comprising: a cellulosic substrate comprising a top surface opposite a bottom surface, the top surface forming a part of the first major surface, the cellulosic substrate comprising at least one defect that forms a depression in the top surface of the cellulosic substrate; a cured polymeric composition formed from a putty composition comprising: an aer luie- unci ionai resin; a filler composition comprising: calcium carbonate particles; and giidani particles selected from talc, magnesium

I stearaie, silicon dioxide, starch, and a combination of two or more thereof; wherein ihe calcium carbonate particles and ih glidant particles are eset in a weigh! ratio ranging from about 4: 1 to about 1 : 1 ; wherein Che cured polymeric composition occupies at Icasi a portion of She depression,

[0005] Other embodiments of the present invention include a method of repairing a cellulosic substn e comprising: heating a eelluiosic substrate having at least one defect that forms a depression in a top surface of the eeS osic substrate to a temperature of greater than about 35^C applying a putty composition to the depression, the putty composition comprising; an aerylate- functional resin; a filler composition comprising: calcium carbonate particles; and glidant panicles selected from talc, magnesium stearaie, silicon dioxide, starch, and a combination of two or more thereof; wherein the calcium carbonate particles and the glidant particles are present in a weight ratio ranging from about 4 1 to about 1 : 1; and exposing the cellulosic substrate to a radiation source.

|(M) ] Other embodiments of ihe present invention include a putty composition comprising: an initiator component comprising a I normal initiator and a photo initiator; an acrylale-functiona! resin; and a filler composition comprising: calcium carbonate particles; and glsdani particles; wherein the calcium carbonate particles and the glidani particles are present in a weight ratio ranging from about 4: 1 to about 1 : 1 ,

BRIEF DESCRIPTIO OF THE DRAWINGS

[0007] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

fOOOS] Figure i is a perspective view of a composite panel containing surface defects that have been treated according to the present invention;

| MMI9] Figure 2 is a cross-sectional view of the cellulosic substrate taken along line ϊΐ-ΐϊ in Figure 1 ;

0010] Figure 3 Is a cross-sectional view of the composite panel taken along line Π-Ιί in figure 1.

DETAILED DESCRIPTION

[Wil l] The following description of the preferred embodiments) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses, 10012) As used throughout ranges are. used as shorthand for describing each and every value thai is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by referenced in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls.

100131 Unless otherwise specified, all percentages and amounts expressed herein and elsewhere in the specification should be understood to refer to percentages by weight. The amounts given arc based on the active weight of the material According to the present invention, the term "about" means 4·/·· 5 % of the referenced value. According to the present invention, the phrase "substantially free" means less than 1 wt. % based on the referenced amount,

[001 ] Referring to Figures i-3 concurrently, the present invention provides a composite panel 1 comprising a celiuiosic substrate 100 and cured polymeric composition 200. The composite panel 1 may comprise a first major surface 2 opposite a second major surface 3 and side major surfaces extending there between 4. The celiuiosic substrate 100 may be formed from wood and comprise a top surface 102 opposite a bottom surface 103 and side surfaces 104 extending there between. The celiuiosic substrate 100 may also comprise natural design features 130, such as a knot, burl, wood-grain, or the like. The celiuiosic substrate 100 may have a thickness t¾ ranging from about ISO mils to about 1000 mils as measured from the top surface 102 to the bottom surface 103 - including all values and sub-ranges there- bet ween. The composite panel 1 may also have a thickness that is substantially equal to the thickness is °^ * ^e celiuiosic substrate 100.

[0015] The celiuiosic substrate. 100 may comprise surface defects 150 that form depressions in the top surface 102 of the celiuiosic substrate 100, Each depression 150 may comprise a floor 151 and side walls 153 --- with the floor 151 being the deepest point of the depression 150. The defects 150 may have a defect depth D _{I 5} as measured from the top surface 102 of the celiuiosic substrate 100 to the floor 151 of the defect 150, where the defect depth DD ranges from about 1 mil to about 100 mils - including all values and sub-ranges there-betweem The side walls 153 may extend upward from the floor 151 and intersect with the top surface 102 to the celiuiosic substrate 100 at. an intersection point 152 - wherein the side walls 153 may extend upward in a direction that Is perpendicula or orthogonal to the top surface 102 of the celiuiosic substrate 100. Each of the depressions J 50 may have an opening distance Do which is the distance measured between the intersection points 152 that exist on opposite side walls 153 for a single depression 150 in ihe celluiosic subs ate 100- The opening d stanc Do of may range from about OA inches to about 2.0 inches - including ail values and subranges iherc-belween.

[ 16] According to toe present invention, the defects 150 on the celluiosic substrate 100 ma he repaired by filling the void created by each depressions 150 wish a putty composition which is cured to form a cured polymeric composition 200, thereby producing ihe composite panel 1 of ihe present invention. As used herein, the term "putty" refers to a soft, sticky, dough-like materia! that hardens after it is cared.

£00171 As demonstrated in Figure 3, the cured composition 200 may form a top repair surface 202 that faces the same direction as the top surface 102 of the celluiosic substrate. The top repair surface 202 of the cured polymeric composition 200 and the top surface 102 of the celluiosic substrate 100 may each form a. part of the first major surface 2 of toe composite panel The top repair surface 202 may be substantially para! lei to the top surface 102, The top repair surface 202 may be substantially co-planar with the top surface 102.

[0018] The putty composition of the present invention comprises a filier component (as discussed further herein) and a reactive composition. The filler component may be present in an amount ranging from about 25 wt. % to about 75 wt. % based on the total weight of the putty composition. The reactive component may be present in an amount ranging from about 20 wt. % to about 50 wt. % based on the total weight of the putty composition.

[9019] The reactive composition comprises one or more acryiate-functional resins. The acrykte-functionai resin may comprise at least one acryiate-functional oligomer and, optionally, one or more acryiate-functional reactive diluents. According to the present invention, the icrms "acrylate-fiinctioriai" and ^4, acr late-functionality" refer to compounds having either acrylate and/or methaerylate functionality. Additionally, the terms "(meth)acrylate" and "{meth)acrylic acid" refer to compounds that may either be acryiate-functional or methacrylate-Functional.

[0020] The acryiate-functional oligomer may be a linear or branched compound having an aerylate-funciionality ranging from about 2 to 9 - including ah values and sub-ranges there between. The acryiale-funciional oligomer may each he selected from an epoxy- based acrylate oligomer, a polyester-based acrylate oligomer, a methane-bused acrylate oligomer, or a combination thereof.

[0021 ] The cpoxy-based acrylate oligomer may be prepared by reacting epich!orohydrin with bisphenol A to form diglyeidyi ethers of bisphenoL followed by the reaction of the diglycidyl eiher of bisphenol product, with acrylic acid and/or (mclh)acrylic acid. The epoxy acryiaie oligomer may be an aliphatic epoxy aery hue oligomer or an aromatic epoxy acryiaie oligomer, The backbone of an aromatic epoxy acryiaie oligomer may comprise an epoxy compound thai includes one to three 3 ,2 -epoxy groups per molecule, and preferably, from a boy I two to about two and one hall ^' {2.5} K -epoxy groups per molecule, A oond nmg example of the epoxy acryiaie oligomer may be a giycidyi eiher of a polyhydric phenol and polyhydric alcohol having an epoxide equivalent vveighi of from about 100 to about 500, The polyhydric phenol may be bisphenol~A, bisphenol-F, or a combination thereof,

0022] The epoxy- ba e acrylale resin may comprise an oligomer of diglycidyl ether of teirabromobisphenol A, epoxy novolacs based on phenol- formaldehyde condensates, epoxy novolaes based on phenol-eresol condensates, epoxy novolacs based on phenol - dicyclopentadsene condensates, diglycidyl eiher of hydrogenaied b phenol A, digykidyl eiher of resorcinol, ieiraglycidyl ether of sorbitol, and tetra giycidyi eiher of methylene dianiline. as well as mixtures of two or more thereof,

[00231 Non-limiting examples of die epoxy acryiaie oligomer is CN- 1.20 (bisphersol based), CN- 132 (diacrylaie low viscosity oligomer) or CN - 133 {triacr late), available from Sartomer.

[0024] The polyester acryiaie oligomer may be the reaction product of polyester polyol and an carbosylie acid functional acrylale compound such as (meth)aerylie acid, (meth)aerylie acid, or a combination thereof - at a OH:COOH ratio of about 1 : 1 , The polyester polyol may have a hydroxy! functionality ranging from 2 to 9 including all values and sub-ranges there-beiween.

[0025] The polyester polyol may he the reaction product of a hydroxyl-functlonai compound and a carboxylac acid functional compound. The h droxy!- functional compound is present in a stoichiometric excess to the earhoxylic-acid compound. The hydroxyl-fursciional compound may be a polyol, such a dioi or a tri -functional or higher polyol (e.g. trio!, ieiroL etc.). The polyol may he aromatic, cyeloaiiphatic, aliphatic, or a combination thereof, The carboxylic acid- functional compound may be a dicarboxylie acid, a polycarboxylie acid, or a combination thereof. The dicarboxylie acid and polycarboxylic acid may each be aliphatic, cyeloaiiphatic, aromatic, or a combination thereof,

[CM>26] The diol may be an !kylene glycols., such as ethylene glycol, propylene glycol, dieihy!ene glycol, dipropylene glycol, methylene glycol, tripropylene glycol, hexyiene glycol, polyethylene glycol, polypropylene glycol and neopciUyi glycol; hydrogenated bisphenol A; cyclohexanediol propanediol including L2-propanediol, 13-propancdiol. butyl ethyl propanediol. 2-methy1- 3 ,3-propanedioi,, and 2-ethyl~2~hutyl- 3 ,3-propanediol; butancdiol including 1,4-bulancdioi. 1.3-butanedtol. and 2-ethyl- i ,4-butancdiol: pentanediol including trimethyi pentanedioi and 2-methylpenlancdiol cyclohexanedimcthanok hexanediol including 1 ,6-hexanediok caprolactonedioi (for example, the reaction product of epsiion-capro!actone and ethylene glycol); hydroxy-alkylated bisphcnol; polyethcr glycols, for example. poly(oxytetramethylene) glycol. In some embodiments, the tri-functional or higher polyol may be selected from rimcthylol propane, pentaerythrftoi. di-pentacrythritoi, trimcthylol ethane, irimelhylol butane, dimethylol cyelohexane, glycerol and the like.

10027] The dicarboxylic acid may be selected from adipic acid, azelalc acid, sebacic acid, succinic acid, glutaric acid, decanoic diacid. dodeeanoie diacid, phlhalic acid, isophthaiic acid, 5- tert-butylisophdiaiic acid, tctrahydrophthalic acid, terephthalic acid, hexahydrophthaltc acid, mcthylhcxahydrophthalic acid, dimethyl tcrcphthalate. 2,5-furandicarhoxylic acid. 2,3- furandiearhoxylic acid. 2,4-furandicarboxylic add, 3.4~furand$earboxy1ic acid, 2,3,5- furantnearboxylic acid. 2,3,4,5-furantctracarboxyUc acid, cyclohexane dicarboxylic acid, chlorendic anhydride. 1 ,3-cyclohexane dicarboxylic acid, 1 ,4-cyclohexane dicarboxylic acid, and anhydrides thereof, and mixtures thereof. In some embodiments the polyearboxylic acid may be selected from Irimellitic acid and anhydrides thereof.

[0028] In some embodiments, the polyester polyol comprises an aromatic polyester polyol that has an acid number of less than about 15, preferably less than about 5, comprising the reaction product of an equivalent excess of one or more polyol* of equivalent weight less than 150 with at least one aromatic polyearboxylic acid. If the polyearboxylic acid is a phlhalic acid derivative the result is a phthalate polyester polyol . Preferably at least 50 equivalent percent of the polyearboxylic acid is isophthaiic acid, phlhalic acid, terephthalic acid, phlhalic anhydride, or di methyl terephth a hue.

[0029] Commercially available polyester acrylale oligomer include polyester-acrylatc resins such as: Craynor® UVP-215, Craynor® UVP-220 (both ex Cray Valley), Genomer® 3302, Genomer® 3316 (both ex Rahn), Sartomer CN2261, CN9005, Laromer® PE 44F, Laromer PE 56F, Laromer 8992, Laromer 8800 (ex BASF), Ebecryl® 800, Ebecryl® 810, Viaktm® 5979, Viaktin® VTE 5969, and Viakdn® 6164 (100%). Q$30J Hie uretbane acryiaie oligomer may have an average acryiaie functionality angin from about 2 to about 6 ^■ ■ ^■ ■ ^■ ■ including all values and sub-ranges ihere-heiween. In a preferred embodiment the ureihane acryiaie oligomer may have an average acryiaie functionality ranging from about 2 to aboul 4 - including all values and sub-ranges there between.

[0031] The urethane acryiaie oligomer may be the reaction product of one or more high molecular weight polyol. polyisocyanate. and a hydroxyl-functional acryiaie. The ureihane acryiaie oligomer may be produced by reading the polyisocyanate and the hydroxyl- unctional compounds at an NCO:OH ratio ranging from about 0.8: 1 to about 1.2: 1 preferably at about 1 : 1.

| 032j The high molecular weight polyol may have a hydroxy! functionality ranging from about. 2 to about 4. Non-limiting examples of high molecular weight polyol include polyester polyol, polyeiher polyol polyoleCin polyol. and polycarbonate polyol having an average hydroxy! functionality ranging from about 2 to about 4. The polyester polyol used to create the ureihane acryiaie oligomer may be the same as the polyester polyol used to form the polyester acryiaie oligomer.

[00331 The polyisocyanate may have an isoeyanate-functionality ranging from about 2 to abou 4. Non-limiting examples of polyisocyanate include aliphatic polyisocyanate, cydoaiiphailc polyisocyanate, and/or aromatic polyisocyanate - such as 1„4-tetrameihyierte diisocyanate. 1 ,6- hcxamcthyicnc diisocyanate (HDI), 1.4-eyclohexyl diisocyanatc and isophorone diisocyanatc, 4,4' diphenyl-meihane diisocyanatc and toluene diisoeyanaies. Polyisocyanate having an isc-eyanate functionality of 3 or 4 may include triisocyanates, biurets, allophanatcs, and isoeyanurates of 1 ,6-hexamet yIerse-diisocyanate and isophorone diisocyanate may be used. The preferred pol isocyanates may inciude trimers of 1 .6~hcx,amefhy1ei e dnsocyanate, which is commercially available as Dcsmodur from Bayer Corporation,

[0034] The hydroxyl-functional acryiaie may have a hydroxyl functionality from about 1 to about 2 and an aeryiate functionality from about 1 to about 3. Non-limiting examples of hydroxy! functional acryiaie include the reaction product of acrylic acid arsd/or (meSh)aerylic acid and a low molecular weight diol or polyol. In some embodiments, the low molecular weight dioi is selected from monoethylene glycol 1.2- and .3-propylcne glycol, 1.4· and 2,3-butyiene glycol. 1 ,5-pentanediol, 1 ,6-hexanediol, 1 ,8-ocianediol, deeanediol, dodeeanediol, ncopcniyiglycol. eyelohexanedsol and mixtures thereof. In some embodiments, the polyol is selected from pentaeryihriiol, neopentylgiyeol. dicidol, trimethyiolpropane, and mixtures thereof. In some embodiments. Ihe did and polyoi may contain alkyl branching or hydroxy alkyj branching such as trimethylolpropane. In other embodiments, the po!yo! comprises a mixture of a polyoi having a h roxyl functionality of three or greater and a dioL In other embodiments, the polyoi may have a chain length of from C¾ to CU or from CS to C ₃ , between ihe hydroxyl groups.

[ΘΘ35] The reactive composition may comprise up to 40 wt % of an acryiate-fimctional reactive diluent Reactive diluents are compounds that serve a dual purpose; such compounds are not only capable of covalently bonding with acry!aie-funciionai oligomer hut a e also capable of reducing the viscosity of the overall putty composition. The reactive diluents may have number average molecular weights of about 226 to about 2000 ~ including ail values and sub-ranges therc-bet een. The reactive diluent may have an aery late functionality ranging from i to 5 - including ail values and sub-ranges there-hetween.

[00361 In some embodiments, the aery I ate- functional oligomer of the reactive component may comprise a blend of epoxy based oligomer and urethane based oligomer in a weight ratio ranging from about 1 : 1 to about 1 :3. In some embodiments, the acr hne- unctional oligomer reactive may be substantially all polyester based oligomer.

10037] Suitable reactive diluents include, but arc not limited to, (mcth)acrylie acid, isodcey! meih)acrylate. N-vinyl fonnamide, isobornyl (meth)acrylate. tetr ethylene glycol <mcth)acryiatc. tripropylcnc glycol (mcth)acryiatc, hcxancdioi di(nteth)acrylate, ethoxylatc foisphenoI-A di(me¾h)acr hHe, ethoxylated itcopentyl glycol di(meth)acrylale, propoxylated neopen!yl glycol di(meih)acrylate, cihoxylalcd tripropylcnc glycol di(mc(h)acrylate, glyceryl propoxy!alcd tri(nieth)acryiatc. Iris (2 -hydroxy ethyl) isocyan rale tri(mcth)acryjaie» pentaerythritol tri(meth)acrylate, pentaerythrkol te ra(rneth)acrylate, dimelhylol propane lri(rncth)acrylatc dipcntacrythiitol monohydroxypenta(mcth)acryiaic, and truncihylol propane !ri(melhjacrylaie and its ethoxylaied and propoxylated analogues of the skeletal structures in Formula 3: 3

[0038] Where R"~H, or CH ₅ . and q«0. L 2, 3, , 5, 6, 7, 8, 9 or ii).

|0039] The preferred (methjaerylaie reactive diluents are. she multifunctional aery Sates with number average molecuiar weights of about 226 to about 2000. Examples of such arc teitaeihylene glycol diacrylatc with a molecular weight of about 302, ethoxylated bisphenoi-A diacrylaie with a number average molecular weigh? of about 776 (SR6Q2 from Sarlomer Company), trihydroxyeihyl isocyanurate triacrylaie with molecular weighs of about 423 (SR368 from Sartomer), trimcthylo! propane triacrylaie with a number average molecular weight of about 296 (5R351 from Sarlomer), and ethoxylated trimclhyiol propane triacrylates with number average ^, molecular weights from about 400 to about 2000 S 454, S 49 , SR502, SR9035, and SR 415 from Sarlomer Company and Pholomer 4155 and Photomer 4158 from Benkcl Corporation). Tetra-functional reactive diluent may comprise penJaerylhritol fetraacrylate. Penta-functional reactive diluent may comprise dipetrtacrythritol pcntaacr lafe.

[0040] Additionally, when Ihe reaciive composition comprises an epoxy-based oligomer, the reactive composition may further comprise an epoxy fiexibilker. Non-limiting examples of flexibslizer includes rubber-modified bssphenoi A epoxies. epoxidixed castor oil based epoxics, and epoxies which are modified with di erked fatty acids, as well as mixtures thereof.

[0041 ] The putty composition further comprises an initiator component comprising a mixture of thermal initiator and a photo initiator. The mixture of thermal initiator and photo initiator provides a dual cure mechanism to the putty composition (e.g., curing by heat and UY radiation) that ensures fast and proper through-cure of the patty composition to form the cured polymeric composition 200, The term "through-cure" indicates that the substantially all of the putty composition that has been applied to one or more defects 150 in the eellulosic substrate 100 has been chemically cured by cross-linking of the free acry!aie groups present on the first aerylate oligomer and the second aery late oligomer (and, optionally, the third acryhte oligomer), thereby forming the cured polymeric composition 200, |CM 42| The dual cure mechanism of the present invention results in through-core for putty compositions applied to depressions having a defect depths Do as high as about 100 mils. Unlike the soft, sticky, dough-like putty composition, the cured polymeric composition 200 Is a rigid, non-tacky material at room temperature that has a hardness of at least the surrounding cellulosic substrate 100. Therefore, the dual cure mechanism provides fast and efficient formation of the cured polymeric composition 200 throughout the substantially the entire defect 150 (up to defect depths Do of 100 mils), which in-ium allows for fast and efficient postprocessing of the composite panel 1 (e.g., milling, surface sanding, abrading, etc.) as the cured polymeric composition 200 can quickly be post-treated in the same way that cellulosic substrate 100 without special concern to a partially cured putty composition,

[1 )43] Depending on the type of reactive composition selected, the type and amount of initiator and solvent may vary. The amount of pholoinitlator should be sufficient to achieve acceptable curing of the composition when it is irradiated bat not so large that it affects the properties of the cured composition in a negative way,

[$044] The photo initiator may be present in an amount ranging from about 0.1 wt. % to about L0 L % based on the total weight of the putty composition - including all values and subranges there- between, in a preferred embodiment, the photo initiator may be present In an amount of about 0.3 wt. % to about 0.8 wt. % based on the total weight of the putty composition ■■■ ^■ including all values and sub-ranges there -be ween.

[0045] The photo Initiator may be water soluble and include benzophenone-iype initiators, phosphine oxides, acctophenonc derivatives, and cationic photo initiators such as triaryl sui onium salts and aryliodonlum salts. The photo initiator may be selected from ben?,opnenone; 4-methylben/ophenone; benzyl dimethyl ketai; diethoxy acetophenone; benzoin ethers; thloxanthones; 1 -hydroxycyc iohexyl phenyl ketone; 2-hydroxy~2~methyb 1 -phenol-propane- 1 - one; 4-(2-hydroxyethoxy)phenyl-(2~hydroxy-2-methyipropyl) ketone; 2,4,6-trimethyibenzoyI dipheny!phosphine oxide; bis {2,6-dimelhoxybenzoyl)-2,4,4-trimeihyipen yl phosphine oxide; ethyl - 2.4.6 Trimcthylbenzoylphcny!p osphinate; 2 ,2 - d i met h ox y · 2 · pheny i acetophenone; 2,2- dimethoxy- !,2~diphenyiethan- -Qne; bss{2,4,6-trimcihylberizoyl)-pheny!-phosphineoxide; 2- benzyi"2~N,N-dimethy1atnino-- l-(4-mojpholinophenyl)- i -buianone; and 2-methyl-l-[4- (rnethyIthio)phenyi] -2-morphoiino propan- 1 -one. and a combination of two or more thereof. 00 ] The photo initiator may be used alone or in combination with other photo initiators. The utty composition may further comprise photosenskizers. Non-limiting examples of pholosensiuzer include isopropyl thioxaruhone, chlorothioxanthone, quinones such as camphorqu ^' mone; 4>4' bis(dimcihylamino)benzophcnonc; 4,4' ^» bj:sdiethyl»mino ber ophenone ethyl ketone; thioxarsthone. benzanlhrone. triphenyl acetophenone and fluorenone, dimc hylethunola ine, rnethyldiethanolamine, iriethanoiamine, .N-dimethyi-para- tolddine. N- [ 2■ h drox eihyij - N -me thy 1- para-toi u idi ne. octyl -para N.N dime hyiamirso benzoa!e, a d ethyl- para- N . N--di methy 1 am i no beozoate .

[0047] The thermal initiator may be present in an amount ranging from about 0.1 wi. % to about LO wi. % based on the total weight of the putty composition - including all values and subranges there-between. In a preferred embodiment, the thermal initiator may be present in an amount of about 03 wt % t about 0.8 wt. % based on the total weight of the putty composition ^■ ·« ^■ including all values and sub-ranges ihere-between. The thermal initiator may comprise a free radical initiator that generates radicals upon exposure to heat rather than light. The thermal initiator may be selected from, a peroxide compound, an a compound, and a combination thereof. Non -limiting examples of azo compounds include 2.2'-a*obis-(2,4* dimethy!valcfonitrile }, azobisi ohutyronifriie. azobisisQheptanonitrile, azobisisopentarsorsitrile, and 2,2'^izobis-{2-me{hy!huiyroniiriIe); 1 < 1 - i£obi$-( I -eydohexanecarbonitrUe).

[§048] Non-limiting examples of peroxide initiators include diacyi peroxides, such as 2-4- djclorobeozyi peroxide, diisooonauoyl peroxide, decanoyl peroxide, lauroyl peroxide, succinic acid peroxide, acetyl peroxide, benzoyl peroxide, and diisobutyryl peroxide, acetyl alkylsulfonyl peroxides, such as acetyl cyclohexylsulfonyl peroxide, diaiky! peroxydicarbonates, such as di{n- propyl) peroxydicarbonate, di(sec-butyl) peroxydicarbonate, di(2 ^« eihylhexyi) peroxydicarbonate, t-b yl-peroxymaleie acid, diisopropyf peroxydicarbonate, and dicydohexyl peroxydicarbonate, peroxy esters such as aipha-camyi peraxyneodecanoaie, alpha-cumyl peroxypivaiale, t-amyl peroxyrseodecaooate, i -butyl peroxyneodecanoate, t-amyl percsxypivalate, t-butyl peroxypivaiate, 2,5-dimethyl~2.5-di(2-ethylbexanoylperoxy)hexane, t amylperoxy-2-ethy! hexanoate, t-butyl peroxy-2-ethyl hexanoate, t -butyl pcroxyisobulvrate. t-butyl peroxyacetaie, t-butyl peroxybenzoate, dl ¾. butyl diperoxy azelate, and di-t-butyl diperoxy p halate, dieumyl peroxide, 2,5-dimethyi-2J-di{t-butyiperoxy)hexane, t-butyl eurayi peroxide, ds-t-butyl peroxide, arid 23- dimethyl2,5-di(t-hutylperoxy}hexyne-3, a hydroperoxide, such as 2,5-dihydroperoxy-2.5-

Π dimethyl hexane. cumene hydroperoxide, i*butyl hydroperoxide and t-amyl hydroperoxide, n- buiy!-4,4-bis-(t-huiylperoxy)valeraSe, l , 1 - ii(t-buiylperoxy)"3,3,5'trime{hyl cyelohexane, U '-di.~ t-amyi-peroxy cyciohexane, 2,2--diit -butylperoxy) butane, ethy 3J<Ii(i-¾stylperGxy)bu yrate. i- butyl peroctoaSe. and I J -di{^buiylperaxy)eyelohexane,

[§049] The putty composition may further comprise free radical inhibitor. Non-limiting examples of free radical inhibitor include N iiitroso -phenyihydroxylamine. ammonium salt. iris[N-niiroso-N-phenyShydroxyiamine. aluminum salt, p-meihoxyphenol jVIEHQ, hydroquinone and substituted hydroquinones. pyrogallol, phenotbiazine, and 4-elhy! catechol, and combinations thereof.

OOSOj The initiator component may further comprise a solvers!., The solvent ma be present Irs the initiator component in an amount ranging from about 0.5 wt.% to about 4 wt.% based on the total weight of the putty composition ~ including all values and sub-ranges therebetween. In some embodiments, the ratio of the solvent to the thermal initiator is from about 4: 1 to about 1 : 1. Non-limiting examples of solvent include an aromatic solvent,, such as tolue e or benzene; and a non-aromatic solvent, such as acetone, chloroform, ethylacetate, or methyl methaerylate, In some embodiments, the solvent comprises acetone.

fOOSl] The patty composition of the present invention may be substantially free of th!o!- functional compounds. According to some embodiments, the putty composition of the present invention may be entirely free of thiol-functional compounds (i.e. comprise 0 wt, % of thiol- functional compounds based on the total weight of the putty composition). The putty composition of the present invention ensures fast and proper through-cure of the putty composition to form the cured polymeric composition 200 even without the addition of thiol - functional compounds, such as tri -thiol.

}©0S2] The putty composition of the present invention may further comprise colorant, surfactant, or combinations thereof. The colorant may comprise a dye, a pigment, or a combination thereof. The colorant may be present in an amount ranging from about 0,5 wt, % to about 8 wt. % based on the total weight of the putt composition - including all values and sub-ranges there-between. The pigment ma include particles that impart yellow, red, green, blue, black, and combinations thereof, to the putty composition. The surfactant may be present in an amount ranging from about 0.1 wt. % to about 1 wt. % based on the total weight of the putty composition - including ail values and sub ranges there-between, [0053] The putty composition ntay further comprise Oiler. The filler may be present in an amount ranging from about 20 wt. % So about 70 wt % based on the total weight of the putty composition --- including all valises and subranges therebetween. Non-limiting examples of filter include glass flit, flour, calcium carbonate, calcium sulfate dihydrate (Gypsum), calcium hydrate hernihydrate, barium sulfate, mica, ammonium chloride, ammonium bromide, boric acid, antimony trioxide. alumina (e.g. fumed alumina), clays such as kaolin, china clay, lithopone, zinc sulfide, zirconium oxide, barium oxide, calcium oxide or hydroxide, magnesium silicate (Talc), oxide or hydroxide, ceramic, hollow glass, hollow microspheres, resin microspheres, pearl essence, barites, iatomaceous earth, aluminum trihydrale, onyx Hour, calcium silicate, mixed silicates, and the like. The hollow microspheres may be zinc hollow spheres.

[1)054] In a preferred embodiment, the filler comprises a blend of two Oilers - a first filler comprising particles of calcium carbonate and a second filler comprising a glidant. The first filler may have a particle size ranging from about 7 pm to about 15 μπι - including ail values and sub-ranges there-between. The second idler may have a particle size ranging from about 1 μπι to about 100 μ ηι (preferably between lum to SCJum and most preferred between i to 15ums) including all values and sub-ranges there-bet ween.

: 01)55) Non-limiting examples of glidant include particles of talc, magnesium stearaie, silicon dioxide, starch, and a combination of two or more thereof. The first filler and the second filler may be present in a weight ratio ranging from about 4: 1 to about 1 : 1 ^■■■ ·■ including all ratios and sub-ranges there-bet ween. In a preferred embodiments, the glidant may comprise talc and ihe ratio of the first filler to the second filler may ranges from about 3: 1 to about 1 : 1 ^■ ·« ^■ including ail ratios and sub-ranges there-bet ween.

[&0S6] In an alternative emhodiment. the calcium carbonate may be replaced partially or entirely with hollow microspheres and the ratio of the first filler to the second filler ranges from about 1 : Ho about 1 ; 10— including all values and sub-ranges there-hc ween,

[0057] The putty composition of the present invention may a viscosity ranging from about 100.000 cP to about 400,000 cP at about 25 °C - including all values and sub-ranges therebetween. In some embodiments, the putty composition exhibits a viscosity of from about 150,000 cP to about 300.000 cP at about 25 *C - including all values and sub-ranges therebetween. In some embodiments, the putty composition exhibits a viscosity of from about 175,000 cP to about 250,000 cP as about 25 ^;> C■ ^■ ■ ^■ ■ ^■ including all values and sub-ranges there- between. The viscosity described herein is measured on a Brookfiekl viscometer at 10 RPM . |IMIS8| The putty composition may further comprise a viscosity modifying agent in an amount effective such thai (he putty composition exhibits die desired viscosity. Non-limiting examples of viscosity modifying agent comprises fumed silica and/or a dispersant. Putty compositions above 500,000 cP at about 25 *C are not suitable for this invention as ease of iroughabiiiiy is dramatically reduced that results in uncured putty pail out of defects in trough process, (putty rolls back up).

[IM S ] The putty composition may be formed by combining the filler and the reactive composition, the initiator component, solvent, and optionally, pigments, and surfactant. In some embodiments, the thermal initiator may be prc-dissolvcd in the solvent before being added to the other components of the putty composition.

fOOo j The composite panel ί may be formed by healing a cellulosic substrate 100 that a defect 150 on the top surface 102 to a temperature of greater than about 35°C. In some embodiments, she cellulosic substrate may be heated to a temperature of from about 37 °C to about 70 ^® C. In other embodiments, the cellulosic substrate ma be heated to a temperature of from about 57 *C to about 66 °C. The bottom surface 103 of the cellulosic substrate 100 may face an upper surface of a conveyor belt or other work surface.

[0061] During one or more stages of the manufacturing process »- including the curing stage, the cellulosic substrate 100 may be processed along a machine direction at a line speed of from about 10 fccl/minute (fpm) io about 70 fpm ~ including all values and sub-ranges therebetween. In some embodiments, the conveyor belt has a line speed of from about 20 fpm to about 60 fpm - including all values and sub-ranges there-bctween. In some embodiments, the conveyor belt has a line speed of from about 30 fpm to about 50 fpm - including all values and sub-ranges Ihere-between. In some embodiments, the conveyor belt has a line speed of about 35 fpm. In some embodiments, the conveyor belt has a line speed of 33 fpm. The cellulosic substrate 1.00 may be processed along the machine direction using a conveyor belt.

[0062] The putty composition may be applied to the defect 150. and the cellulosic substrate 100. In the defect 150, the putty composition forms a putty top surface that faces substantially the same direction as the top surface 102 of the cellulosic substrate 100. The cellulosic substrate 100 may then be exposed to a radiation source and the putty composition cures to form the cured polymeric composition 200 within ihc cellulosic substrate 100, thereby forming the composite pane! 1 of the present invention. The putty top surface may be exposed to atmospheric conditions during curing, Stated otherwise, the putty top surface is not covered by art external membrane or protective film layer during exposure to the UV radiation during curing. Rather, the putty top surface of the putty composition and at least a portion of the top surface 102 of the cellu!osic substrate 100 are exposed to the surrounding atmospheric conditions during curing. Thus the top putty surface forms the top repair surface 202 while exposed to atmospheric conditions and not under the protection of an external layer and/or membrane,

[§§63] The celkdosie substrate 100 having the putty composition applied thereto can be cured by conveying the cellulosic substrate 100 along the machine direction wherein the radiation source is located above the cellulosic substrate 100 and conveyor belt, facing downward. As the cellulosic substrate 100 and putty composition applied there to pass underneath the radiation source, the putty composition is exposed So the UV radiation that is emitted from the radiation source.

[0§6 J The radiation source may comprise ultraviolet radiation. The radiation source may be a UV lamp that, emits UV radiation having a peak irradianee ranging from about 350 niW/cnV ^" to about 4000 mW/cm ² - including ail values and sub-ranges there-between and as measured by using an HIT Instruments pack or mapper in the UVA regime. n some embodiments, the radiation source may emit UV radiation having a peak irradianee ranging from about 350 rnW/cm" to about 1 ,000 mW/cnr ··· including all values and sub-ranges ihere-beiween. The radiation source may be a mercury vapor UV lamp or an LED emitting radiation lamp, wherein the radiation that is emitted has a wavelength in the range of about 350 nm to about 400 rsm -- including all values and sub-ranges there-between. The LED may emit radiation at a wavelength ranging from 365 nm to 395 nm and have a LED peak irradianee as high as 20 W/cm ^" as measured by Nobel Probe,

[0065] Moving along the machine direction at the above referenced line speed, the putty composition applied to the cellulosic substrate 100 can be cured with UV radiation from the radiation source, wherein the UV radiation output required to cure the putty composition (including complete through cure) totals to an amount ranging from about 300 mj/cm ³ to about 4000 mJ/cnr - including all values and sub-ranges there-between. Additionally, the putty composition may be cured with as little as a single pass under the radiation source. In other embodiments. S e cellulosie substrate 100 having the putty composition applied thereto may be cured by passing underneath ihe radiation source with multiple passes -- e.g., 2 to 10 asses ^■ · ^«■ including all value and sub-ranges thcre-hetween. The composite panel 1 may then be cooled at a surface temperature ranging from about 54 °C to about 63 *€ ··■ including all temperatures and sub-ranges there-bet ween,

PMI66] In a preferred embodiment, the ceii lostc substrate 100 having the putty composition applied thereto can be cured with a single pass under the radiation source, which provides for a continuous manufacturing process of flooring materials and products that further includes defect repair. Stated otherwise, using the putty composition of the present invention provides a useful way to repair surface defects 150 in cellulosie substrates 100 without having to temporarily separate the celkiosic substrate 100 from a continuous manufacturing process - e.g., stopping inline flooring material manufacture so that a celiulosie board may be removed from the in-line production and relocated to a separate isolated repair process. Rather, detects 150 in cellnlosic substrates 100 can be repaired along the overall continuous manufacturing process such that the defects can he repair immediately after the initial processing of the cel!u!osic board (e.g., board milling) and immediately before further processing steps (e.g., board sanding, additional cutting, surface staining and/or sealing) without the need to pause the overall manufacturing process for surface defect repair. With a single pass, the defects in the cellulosie substrate can be repaired along a conveyor otherw se intended to shaping, sanding, and /or staining the eellulosfc substrate in an effort to create a flooring material

IIMI67] The enhanced tfoughabilily and dual cure mechanism of the putty composition allows for faster manufacture of the overall composite panel I as the putty composition can be applied, 1 roughed (i.e., physically manipulated into the depression 150), and fully eared to a total depth up to 100 mils within a quick and continuously process. The term "continuous process" means that the cellulosie substrate have surface defects can he identified, filled with the putty composition, and fully cared without need for the cellulosie board to be temporarily removed from the overall manufacturing process. Stated otherwise, using the putty composition of the present invention eliminates the need for temporary stoppage of manufacturing for a side-process to repair surface defects. Rather Ihe putty composition of the present invention allows for continuous manufacture of flooring materials wherein the materials can be repaired concurrently

Its wilh the otherwise main manufacturing steps (i.e.. .surface sanding, dimension cuttings, surface staining).

10068] In non-limiting embodiments, a flooring panel may comprise the composite panel 1 of the present invention. The flooring panel may further comprise an underpayment applied to the second major surface 2 of the composite panel I , The flooring panel may further comprise a wear layer applied to the first major surface 1 of the composite panel I .

[0069] The invention will be described in grcaier detail by way of specific examples. The following examples are offered for iliuslralive purposes and are not intended to limit the invention in any manner.

EXAMPLES

[0070] Described in Table 1 (below) are ihc compositions of four (4) exemplary putty compositions of the present invention (Ex, 1 --- Ex. 8). along with the compositions for two (2) comparative putty compositions (Camp. Ex. 1 Ccmp. Ex. 2).

pift?l] The examples each contains an aeryktc- functional resins, as described herein:

| 072] Resin A is a blend of 65 wt. % epoxy based acryiate with 35 wt. % urelhane based acryiate,

[§§73] Resin B is a blend of 64 wt. % of leira- functional urelhane acryiate and 36 wt. % of reactive diluent. The urethane acryiate being the reaction product of:

i, 51 wt, % of Polyester polyol having a hydroxyl number ~ 185. acid number < 0,5 and prepared from 20,0 equivalents of phihaiate anhydride 23.8 equivalents of 1,6- hcxanediof 6,0 equivalents of glycerine;

ii, 35 wt. % of isocyanurate of HDI (commercially available us Desmodur N ^T 330O from Bayer); and

iii, 14 wt, % of hydroxyacrylatc (commercially available from Union Carbide).

|IM)74] The reactive diluent of Resin B comprises a blend of 44 wt. % of irimethylol propane triacrylate (commercially available as SR35 I from Sarlorner); 28 wl, % of ethoxylated (degree = 6) of trimethylol propane triacrylate (commercially available as SR499 from Sartomer); and 28 wt. % of ethoxyiated (degree - 9) of irimethylol propane triacrylate (commercially available as SR502 from Sartomer) . [00751 Resin C Is a blend of about 60 wt. to about 70 wt % of di-functional polyesier acrylaie and about 30 wt, % to about 40 wt. % of reactive diluent. The polyester acry!ate being the reaction product of acrylic acid and a polyester diol in a COOH-OH ratio of i: l. The polyesier diol being the reaction product of:

iv. 1.0 equivalent of trimellUie anhydride;

v, 2,0 equivalents of 1,6-hexunedioi; and

10076] The reactive diluent of Resin C comprising ethoxylatcd trimethyiol propane triacrylate, having a degree of aikoxylation ranging from about 15 to about 20,

[0077] Resin D is a blend of 87 wt. % of polyester acryiatc oligomer (commercially available as CN 2262 from Sartomer) and 14 wt. % of dipentacrythrtol pentaacryiate (commercially available as SR399 from Sartomer).

[0Ο78Ϊ Exam les 1-8

[0079] Each putty composition was prepared by mixing the resin, filler, initiator, and other auxiliary materials (e.g., pigment, dispersants, fumed silica) with mechanical agitation. Each example further included a cellulosic substrate that was subjected to a pre-heat step before application of the corresponding putty composition. The pre-heat step included passing the cellulosic substrate under UV lamps to achieve a board surface temperature (SST) of 37 *C to 55 °C prior to application of the putty compositions. Subsequently, each putty composition was applied to d filled defects on a cellulosic substrate by using cither a plastic dropper or another dispensing device. The defects included knot holes having a depth of about 80mil. Each treated cellulosic substrate was then passed under UV lamps - thereby initiating UV curing of the putty composition. The UV radiation of each example is set forth below in Table 1.

*** Absence of "through cure" is confirmed by the oozing of uncured ptttty from the sides of a defect after the tie is pressed. [0080] The troughability and ρΐη-hoic performance of each example is set forth below in ^" fable

10381 J As set forth in Table 2, troughability was measured by the putty composition being able lo be applied to a defect either by machine or by hand using ;s putty knife and the putty composition being present in the delect and exhibiting minimal self-rolling characteristics, whereby the putty composition retains a substantial degree of its shape or orientation as it exhibited immediately before application to the defect. Acceptable troughability allows for the putty composition to be properly applied to the defect with minimal amounts of effort while unacceptable troughability requires additional pressure and working in order to get the putty composition into the desired shape and orientation of the surface defect.

[0082] As demonstrated by Examples 1 to 7 in Table 2, the addition of a filler component comprising a calcium carbonate and a giidam in a weight ratio ranging from about 4: 1 to about 1: 1 not only provides a wood putty thai is not only easily troughahle (i.e., can .be easily worked by hand or machine in preparation of application to a eellulosic substrate comprising surface defects), but surprisingly forms a cured composition that exhibits superior pin-hole performance ^■ · ^■ · ^■■ i.e.., there are IHtie-to-no pin holes in the cured composition. Such pin~ho!d performance is critical to defect repair in wood because the final appearance of the cured composition must closely resembles the surrounding eellulosic substrate - which is undermined by the presence of pin-holes

IIMI831 Example 8

[00841 As shown in Comparative Example 2 --- the absence of CaC03 particles may provide a troughab!e putty composition, however, the resulting cured composition exhibits inadequate pin hole performance (i.e., the appearance of too many pin holes to be used as a commercially acceptable building product™ such as a flooring product). However, H has been surprisingly discovered that the addition of hollow microspheres - in as little as about 3 wt. % ~ can offset the inferior pin hold performance of the resulting cured composition - as demonstrated below in

Table 3.

* Ingredient contain

** Phosphoric acid polyester

*** Troughable: Yes (Y); No (N)

**** Pin Holes: Acceptable (A); Unacceptable (U) [0085] It is iMeoded that any patents, patent applications or printed publications, including books, mentioned in this patent document be hereby incorporated by reference in their entirety.

[0086] As those skilled in the axi will appreciate, numerous changes and modifications may be made ID the embodiments described herein, without, departing from the spirit of the invention. It is intended thai, al l such variations fail within the scope of the invention.