NZ719960B2 - Lignin-based waterproof coating - Google Patents

Abstract

method of forming a coating on a substrate is provided comprising forming a lignin solution by at least partially dissolving lignin in a solvent, coating the lignin solution onto the substrate and exposing the lignin coated substrate to a treatment selected from the group consisting of a heat treatment and an acid treatment. The coating provides for improved waterproofing and/or strengthening of the substrate. tment and an acid treatment. The coating provides for improved waterproofing and/or strengthening of the substrate.

Description

(12) Granted patent specificaon (19) NZ (11) 719960 (13) B2 (47) Publicaon date: 2021.12.24 (54) LIGNIN-BASED ROOF COATING (51) Internaonal Patent ficaon(s): C09D 197/00 C08L 97/00 D21H 19/14 D21H 21/14 (22) Filing date: (73) Owner(s): 2014.10.20 QUEENSLAND UNIVERSITY OF TECHNOLOGY (23) Complete specificaon filing date: (74) Contact: 2014.10.20 FB Rice Pty Ltd (30) Internaonal Priority Data: (72) Inventor(s): AU 2013904015 2013.10.18 EDYE, Leslie Allan TIETZ, Albert John (86) Internaonal Applicaon No.: (87) Internaonal Publicaon number: WO/2015/054736 (57) Abstract: A method of forming a coang on a substrate is provided comprising forming a lignin soluon by at least parally dissolving lignin in a t, coang the lignin soluon onto the substrate and exposing the lignin coated substrate to a treatment selected from the group consisng of a heat treatment and an acid treatment. The coang provides for improved roofing and/or thening of the substrate.

NZ 719960 B2 WO 54736 LiGNlN-BASED WATERPROOF COATiNG FIELD OF THE iNVENTiON The invention s to the tietci of coating technoiogies. More: uieriy, this invention rotates to a method of forming a waterproof coating on a substrate and to itions for use therein.

BACKGROUND TO THE tNVENTiON Any reference to background art herein is not to be construed as an admission that such an constitutes common genera! knowieoge in iia or elsewhere.

The use of waterproof coatings on a range of substrates is common in a wide range of eppiioetione. One examote is the waterproofing of paper and paperboard products used in the food packaging and transportation industries. it is important in these apoiioetione to protect the food trorn the ingress of re which may effect the quality of the food or even. cause spoiling.

Waterproof gs also preserve the packeging’s structure! ity in high moisture environments.

Existing waterproof gsof card and corrugated paper packaging are often made from wax which may provide an effective barrier to water out which are difficult to reoycte. Other Waterproof coatings are known which contain a range of polymeric hydrophobic components atong with fitters and the iike. These fitters and other agents are typioeiiy required to piece the paper substrate into a suitebte state for attachment of the eotuei waterproofing agent.

This requires a delicate oaiance in the formulation whereby pH and temperature conditions are optimai for eii of the individuai components to exert their effect.

These fitters and other preparatory agents are often fess than satisfactory in their performance and i the coating formulations become oomptioated in terms of the number of components, required to achieve the effect. The ce of these muiti-functionat components also increases the cost to the ers {0306] WC ESM‘i teaches a composition and method for treating paper products with a iigninosulfonetefkreft lignin blood formuietion in a mixture of ts to improve th and humidity resistance, described es the preservation of strength in a high humidity environment. The process reiies on penetration of the formulation into the paper to bond the fibres together with optional use of sugars to heip penetration of the iignin and optionai heating.

W0 QUOGIOZSM‘l does not e for water barrier properties even though some incidents! improvement in initiai water resistance is observed. it eiso requires very high coating weights of formuiation to achieve adequate penetration and has a significant amount of undissoived soiids in the formulation which is undesirabie. {0007‘} RU2076125 (Deineko) generates an oxidised lignin end then employs this as a binder for wood fibres which undergo a hot pressing to form the float particie board. While some water resistance is claimed this process primeriiy s iignin as a binder and does not resuit in a usetui water barrier. it aiso relies on unnecessarily comoiicateci ore—treatment steps for the iignin. it wouid be useful to e for a method of forming a waterproof coating on a substrate, i‘nciuding a paper or a paper t, which is simple, effective and recyciabie.

OSJECT OF THE iNVENTiON it is an aim of this invention to provide for a waterproof g for a substrate which overcomes or emetioretes one or more of the disadvantages or problems described above, or which at ieest provides a usetui attemative.

Other preferred objects of the present invention wit! become apparent from the following description.

SUMMARY OF lNVENTlDN {0011] According to a first aspect of the invention, there is provided a method of forming a coating on a substrate ing the steps of: (a) forming a lignin solution by at" least oertiallydiesoiving a iignin in a soivent; (o) coating the iignin solution onto the substrate; and to) exposing the lignin coated substrate to a treatment selected from the group consisting of a heat treatment and an acid treatment, to thereby form the coating on the substrate. {0012] Preferably, the lignin is obtained from soda, eodeenthraquinone, organsolv g liquors, Kraft black iiquor, eliulosios or lignin containing biomass materieis from any plant origin. Lignoeulfonetes recovered from the spent pulping liquids (red or brown liquor) of suiiite puiping may be usefui out are tees preferred. Benin—based nds obtained by chemise! modification of iignins sourced from pulping and separation processes, for example the removal of sulfonate groups form lignosulionetes, may eiso be used. {0013] The lignin on comprises lignin as the major waterproofing agent. in one embodiment, the lignin solution consists eesentiaiiy of lignin as the active roofing agent. in one embodiment, the lignin solution ses iignin as the sole waterproofing agent. {0014] The lignin on comprises lignin as the major strength enhancing agent. in one embodiment, the lignin soiution consists esseniieily of iignin as the active strength enhancing agent. in one embodiment, the lignin solution comprises iignin as the sole strength enhancing agent in one ment, the lignin soiution substantialiy comprises Iignin as the only non~soivent component. {0016] A second aspect of the invention resides in a composition which Comprises tignin, as the major active component, at teast partiaiiy dissotveci in a solvent. [001?] in one embodiment. the Eignin is subatentietiy oompietety dissoived in the solvent.

The compoeition may he as described for the first aspect. Preferabty, the solvent is such that an ne soiution is . {0019] in one embodiment, the composition consists essentiatiy of iignin. as the active component. in a further embodiment, the composition consists of Eignin, as the active component. [0921.] The composition may further comprise a deodorising agent andi‘or a plasticiser, as described for the first aspect.

According to a third aspect of the invention there is provided a use of the composition of the second aspect to form a coating on a substrate.

The use wit: be as described in each statement made in relation to the first" aspect as if each of those statements was d expiioitty tor the third aspect.

A fourth aspect of the invention s in a substrate comprising a coating formed, by the method of the first aspect. {0025] The substrate may be as described for the first aspect.

The various features and embodiments of the present invention, referred to in duai sections above appiy, as appropriate, to other sections, mutatis mutandis. Consequentiy feature-s specified in one section may be combined with features specified in other ns as riate. {002?} Further features and advantages of the present invention wit! become apparent from the fotiowing ect description.

BRIEF DESCRiPTiON OF THE DRAWENGS {0028] in order that the invention may be readii‘y understood and out into prantioai effect, preferred embodiments wiii now be described by way of exampie with nce to the accompanying figures n: FiG “i is a graphicai representation of the effect of anneaiing temperature on the waterproof coating for a iignin composition of the invention; HS 2 is a oai representation of the effect of anneaiing temperature on the waterproof coating for a deodorised Iignin composition of the invention; FiG 3 is a graphicai representation of the effect of coating weight on the waterproof coating for a iignin composition of the invention; Fit?) 4 is a graphioai entation of the effect of both annealing temperature and duration on g quaiity; FiG 5 is a graphioai representation of the obtained Cobb values of a iignin and 20% giyoeroi ning ation coated onto iinerboaro at ent coating appiioation weights (Rod 1 —— Rod 8) and anneaiing conditions (140, ton and 180°C); {0034] HQ 6 is a graphicai representation of the obtained Cobb vaiues of a iignin and 10% giyoeroi containing formuiation coated onto iinerboarci at different coating application weights and annealing conditions (160, $0 and 220°C); and {0035] HQ: 7 is a graphical entation of the obtained Cobb vaiues of iignin and 20% giyceroi containing formuiation coated onto iinerboard with varying annealing duration.

DETAiLED DESCRiPTiON OF THE DRAWINGS The present invention is predicated, at ieaet in part, on the finding that a highiy affective waterproof ancifor strengthening coating can be formed 2014/000987 on paper by, in certain ments, coating the paper with s simpie soiution of iignin. in further embodiments the g can be formed with lignin and giyoerol. The coated iignin is then subiected to either a thermei annealing step or to an acid treatment step. Both of these steps result in a ormation of the iignin coating, when dried, to form a giossy shiny coating which shows commercially useful ieveis of water resistance. it has not been appreciated in the art that such an effective waterproof andior strengthening coating couid he achieved using iionin as the motor or sole active waterproofing and strengthening agent, Unless defined otherwise, alt technioat and scientific terms used herein have the same meaning as wouid be commonly understood by those of ordinary skiil in the an to which this invention beiongs.

As used herein, the term “iignin” refers generaiiy to lignin—based compounds or oligomersfipoiymers that are insoluble or oniy speringiy soluble in water but for the major part soiuoie in s alkaline or, at toast partiaiiy e in mildiy acidic soiutions. Lignosuifonates may also be used in the present process, with modifications, but are iess preferred. Oxidised Iignins are also tees preferred. {0039] As used herein, the term “waterproof” or “titraterproofing” is synonymous with Water-resistant" and is used to indicate an improvement in the waterproof or wetsnresistant properties of the substrate to which the tignin coating is applied. These terms are not to be cted to requiring that the g forms a water impermeabie barrier under at! conditions. {0046] in one embodiment, the term “waterproof" or “waterproofing“ is used to indicate that the coating, after appropriate heat or acid treatment, forms a barrier which substantially prevents the ingress of water into the ate in an industry standard Cobb 30 test when the substrate is contacted with tiquid water. {0041] The phrase e roofing agent”, as used herein, refers to a component of a soiution, composition or to-rmuiation which, after the riate coating and post—coating treatment steps, activeiy forms 3 r to resist the ingress of water into the substrate. {0042] As used herein, the term “strengthening” refers to an se in the physicat strength andior resilience of the substrate after the coating of the ion has been formed and treated therein compared with those characteristics of the substrate prior to coating. The increase in strength can be determined by standard industry means such as, for exempts, ring crush testing med according to set international standards. [(3043] The phrase “consists essentially of”; as used herein, means that the element: or component which foiiows forms the main active in the soiution, composition, formuiation or coating. in particular it is used to mean that the element or component which toiiows forms greater than 50%, 60%, 75%, ?5%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% by weight of the active waterproofing andtor strength enhancing agents. in one ment, the phrase is used to mean that the element or component which foiiows is the oniy active waterproofing andror strength enhancing agent and any other nts or ents which are present, such as deodorizing agents or piasticisers, are not active waterproofing ancilor strength enhancing components. it is preferred that the waterproof and/or strengthening capabiiity of the final coating is substantiaily provided by iignin atone.

The phrase “consists oi”, as used herein, means that the element or component which toiiows is the oniy active waterproofing andlor strength enhacing component in the soiution, composition, ation or coating. Other nonsoivent elements or components may oniy be present in trace amounts, {0045] in a first aspect of the invention, there is provided a method of forming a coating on a substrate inciuding the steps of: (a) forming a iignin soiution by at least pertieiiy dissoiving a iignin in a soiveni; (is) costing the iignin solution onto the substrate; and (c) ng the iignin coated ate to a treatment selected from the group consisting of a heat treatment and an acid treatment, to y form the coating on the substrate. in one embodiment, the coating is a roof coating. {0047] in one embodiment, the coating is a water resistant g. in one embodiment, the coating is a strengthening coating. in one embodiment, the substrate is seiected from the group consisting of iignoceiiuiosic substrates, iignoceiiulosic derived ates, celluiosic substrates and oeliuiosio derived substrates. {0050] Suitsbiy, the substrate is selecten from the group consisting of a paper or a paper product, a wood or wood veneer, a cotton or other naturei fibre fabric, mouicied puip and mouided fibre materiais, sugar cane bagasse- based materials, tapioca—based msteriais, com starch-based materiais and biomass composite materiais. A range of paper and paper products, such as oaperboard, can be coated with the iignin compositions of the present ions. Any based ate which is required to have water—resistant or improved physicei strength characteristics could be coated in aocordence with the present invention and such substrates woutd be weii known to those in mean The substrate is a non-metai substrate. {0052] Pretera‘biy, the substrate is a formed substrate prior to coating by which it is intended that the coating is not appiied during manufacture or formation of the substrate when the physical components of the substrate have not yet been bound together. in the case of paper or mouided wood fibre products, by way of example, this means that the coating is aopiied to the fatty formed ate rather than being ated into the fibres prior to ng to act as a binder. The fuiiy formed so e refers to the product or sheet onto which the coating is appiied and it wiii be appreciated that this substrate itseif may then become internaiise-d as part of a iarger complex product. The present coatings thus substantiaiiy sit on top of the formed substrate and do not ate internaliy to any significant degree to impart the waterproofing andfor strengthening properties. The formed substrate inoiudes a substrate, such as a paper substrate, which has not yet undergone converting operations but is stiii considered to be a formed substrate. {0053] Thus, in one embodiment, the coating step is a g of the iignin solution onto substantiaiiy oniy an externai e of the substrate. The g is not performed on any t of the substrate which wili become an internai part of the formed substrate. in one embodiment, the method is a method of forming a coating which remains on substantially oniy an externai surface oithe substrate. For the sake ot’oiarity, and as mentioned above, the substrate which has the coating sitting on an external surface thereof (and not internaiised within to any significant extent} may become an internai part of a. iarger t but the coating stiii oniy Site on the surface of the substrate onto which it was aotuaiiy coated. For exampie, a cardboard substrate may be coated on one side and the oarboard then used as an outer wait of a corrugated cardboard product having at ieast two outer waits and an inner fluted iayer. The coated side of the substrate may be positioned to face aiiy into the tinted layer.

Thus, white the substrate iteeif has a coated iayer facing internaiiy into a iarger product the coating of the present invention does not to any substantiai extent become internaiised within the substrate per so.

The solution may he a mildiy acidic, neutrai or alkaline soiotion.

Preferabiy, the Eignin soiution is an alkaiine iignin soiution. The aikaiine aotution may be an ammonia soiution, an aikaii metai hydroxide or carbonate solution or an alkaline earth metal ide or carbonate solution. Preferred alkaline solutions will be those which are volatile and so are easily removed from the coating with minimal or no residue left behind to potentially interfere with the coating. {0055] Preferably, the solvent is an aqueous ammonia on. Ammonia has proven to be particularly effective in dissolving the ligni’n to form an appropriate solution for coating. Further, ammonia is volatile and so it does not leave a matic residue on drying. However, any alkaline solution which is capable of dissolving the iignio within a reasonable volume and subsequently being easily removed may be appropriate. Alkalis which may damage the substrate or which will leave a sell residue upon ation which may interfere with the waterproof anti/tor strength enhancing g are to be avoided. {0056] Preferably, the iignin is obtained by separation, for example by acidification} from soda, soda—anthraoulnone or olv pulping liquors. The lignin can also be obtained by known s of extraction: from lignocellulosics or iignln containing biomass materials from any plant origin.

Lignin obtained by separation, for example by acidification, from Kraft black liquor may also be used. Lignosolfooates recovered from the spent pulping liquids (red or brown liquor) of subtle pulping may be useful but are less preferred. Lignimbased compounds obtained by chemical. modification of s sourced from g processes, for example the removal of sulfonate groups form lignosullonatee, may also be used. [605?] in one embodiment the lignin is a natural, unmodified or non— derivatised lignin. in one preferred embodiment, the lignin is a soda pulp lignin. {0059] in one ment, the iignin is not an ed llgnin, {0060] in one embodiment, the iignin is not a lignosulfonate lignin. {0081] The iignin soiution ses iignin as the major waterproofing andior thening agent. in one embodiment, the iignin solution consists essentially of iignin as the active waterproofing andror strengthening agent. in one embodiment, the iignin soiution comprises iignin as the soie waterproofing endlor strengthening agent- This is a key difference between the present coating compositions and those of the prior art. Some prior art coating compositions may use iignin as one of the components but it is always in combination with other active agents including fiilers and waterproofing agents of different oiasses. indeed most often the iignin which is present in these compositions is not ly there because of any inherent waterproofing or strengthening properties but rather is itseif acting as a filter. ln contrast, the present inventors have discovered that an extremeiy effective waterproof barrier writer a consequent increase in the physioai th of the substrate can be formed using a composition in which iignin is the oniy active waterproofing and thening agent. in fact, other than optionai deodorising treatments, which may be required to address any inherent odour from the , and very smeii amounts of optional piesticisers, iignin may be the only component which is present in the compositions. lo one embodiment, the iignin solution ntieiiy comprises iignin as the oniy ivent component. This is the s-impiest form of the present waterproofing and/or strengthening compositions wherein lignin is ved in a solvent; preferably in an ammonia solution. No further agents or additives are required for this to be on effective coating once it has been suitably ily enneeied or exposed to a pH reduction (acid treatment). {0064] it is an advantage of the t invention that oniy iignin is used as the active waterproofing andfor strengthening agent and so the coating treatment reiies on renewebie resources and is entirety and easily recycilebie. [008.5] in one embodiment, the iignin soiution substantiaiiy comprises Iignin as the oniy non~soivent component. {0086] it is an advantage of the present invention that the use of, uiarly, an ammonia soiution resuits in substantieily oompiete ution of the iignin. in WC) 00128141 the use of a mixed t to address the varying solubilities of the s used, partiouiariy at the higher iigninisoivent ratios, means the Iignin is onty partiy diseoived and a considerebie portion of the iignin is present as a oartiouiate suspension. in the present iignin on the lignin is eubetantiaiiy oompietely or predominateiy dissolved thereby providing for an improved finish in the dried coating. in one embodiment, the iignin is substantiaiiy completely dissolved in the sotveni. in one embodiment, the iignin solution, prior to coating, has an undissolved soiide content of less than 5%, 4%, 3%: 2%, 3.0%, 0.5%. 0.25% or 9.1% by weight of the on. [008.8] in an embodiment, the lignin soiution may comprise, in a % by weight of the soiution amount, iignin in between it) to 40%, it} to 35%, 10 to: 36%, ”£0 to 25%., “£5 to 40%, 15 to 35%, 15 to 30% or 15 to 25%, inclusive ofebout i6, 171 18, 19,20, 21122123 or 24%. in one embodiment, the iignin solution may r comprise an agent selected from the group consisting of sugars and sugar alcohols. Sugars may be selected from the group consisting of monosaocharides, disacchandes and poiysaooharide sugars. Sucrose is one favoured exampie of a disaocharide but a wide range of' such sugars are known to those skiited in the an. in one embodiment the sugar alcohoi is a poiyoi is seieoted from the group consisting of ethylene giyooi, giyoeroi, erythritoi, threitoi, erabitol, i, rihitoi, ol, oi, gaiaotitol, tucitoi, iditoi, inositolt voiemitoi, isomaity maititoi and iactitol. {00?0] in one embodiment, the Iignin solution may r comprise a C12 to Cu pOiYOi, This is inoiusive Of 02 to C12, C; to Cm, Cg to Ca, Cg {C Ce, Cg to C4, (33 to 013, C310 cm, (33 to C5; Cato Cs, inciusive of C2, ()3, Ci, ()5 and Cs poiyois. [00?1] in a preferred embodiment, the polyoi is glycerol‘ it has been found that the use of giyoeroi, above a certain “/0 by weight amount, surprisingiy ailowo WO 54736 the annealing ature empioyed in the heat treatment step to be significantiy reduced compared to that required after coating with a sotution containing iignin atone to achieve the some water barrier endfor strengthening efficacy. This is oounterinizuitive as, although oi may be. used as a plesticiser in emaii amounts in certain applications, it wouid he expected that higher ievets of ol wouid actuaily increase water absorption due to the presence of ie yi groups. it would aiso he expected that higher ieveis of giyceroi would resuit in a coating which wouid be greasy to the touch and easily removed and hence reduce any gains in physicei strength of the substrate. The present inventors have found this is not the case and while the addition of giyceroi is not essential it has benefits in reducing the required annealing temperature and ing for an improved water resistant and/or strengthening coating. {0072] While not wishing to be bound by any partiouiar , the inventors oostuiate that upon heating some of the giyceroi reacts with ammonia to form amides. These amides are more voiatiie than giyceroi itseh‘ and depending on the temperature at the paper surface may decompose. The inmation of the amides and their subsequent decomposition are exothermic reactions which serve to increase the temperature at the paper surface. The reaction with ammonia aiso decreases the pH and drives the giass transition event in the same manner as acid anneaiing and higher ature anneaiing do. {0073] The , preferabiy gtyceroi, may be present in a % by weight amount of the iignin soiution of between {H to 35%, including 0.1 to 30%, 0.1 to % and 0.1 to 20%. in one ment, the poiyoi, preferably giyceroi, is present at t to 35%, including i to 30%, t to 25% and t to 20% or 5 to 35%, including 5 to 30%, 5 to 25% and 8 to 20% or 8 to 35%, inciuding 8 to 30%, 8 to % and 8 to 20%. in one embodiment, the poiyoi, preferably giyceroi, is present at 10 to 35%, inciuding it) to 30%, to to 25% and 10 to 20%. in one embodiment, the poiyol, preferabiy giyceroi, is present at 15 to 35%, including to 30%, 15 to 25% and 15 to 20%. 2014/000987 {00?4] in one embodiment, the lignin soiution substantiatiy comprises iignin, giycerol and a plasticiser as the only non—soivent components. {0375] The piasticiser may be seiecteci from the group consisting of a naturai or synthetic iatex, a poiyether, a gtycol, a oicarboxyiic or tricarboxyiic ester! 3 phthaiate, an aikyi citrate and an acetyiated monoglyceride. {0078] The plasticiser may be a non—giyceroi piesticiser.

The oiasticiser may be present in a % by weight amount of the iignin solution of n 0.1 to 10%, including at . to 8941,01 to 7%, 0.1 to 6%, E31 . to %, 0.3 to 4%, 0.1 to 3%, preferably 1.0 to 5%, more preferably 2 to 4% and even more ably about 2.5, 3.0 and 3.5%. The plasticiser assists in improving the physics! properties of the coating and is not essential to achieve a water resistant andfozr strengthening coating and is not an active waterproofing or strengthening component itself.

[DIES] in embodiments, the iignin soiution, at the time of coating, has a viscosity of between St) to 4560 mPa‘s. Preferably, the viscosity of the lignin solution at coating is between about 100 to, 4000 mPa's, more ebiy between about 200 to 3000 mPa's, even more preferabiy between about 300 to 2000 , still more preferabiy between about 350 to 1500 mPa's and more preferebiy stiii between about 359 to about 1200 mPa‘s. {00?9] The t inventors have found that the waterproofing and/or strengthening properties of the coating do not depend eiiy upon the viscosity of the solution and a wide range of viscosities can stiit resuit in an effective waterproof andfor strengthening coating- This is ularly so with the thermai ing ent as even very dilute, low viscosity soiutions wili Jose water and pass through a more concentrated anti supersaturated state. With the acid treatment it may be preferebte that more concentrated soiutions are employed. in practice! terms, industry standards dictate that higher viscosity solutions are preferebie as the current coating machines in wide use operate iiy with a solution having a viscosity in the 350 to 1200 rnPe‘s range. For this reason this is a preferred viscosity range pureiy because it provides ages in operationat adaptabiiity. {0980] Suitabiy‘, the pH of the tignin soiution at coating is bis-Ween about 5.0 to 12.0 or between about 61.5 to ‘l 1 .(3, abiy between about 720 to 9.5, more preferably between about 7.5 to so and even more o‘reterehiy n about 8.0 to 8.9 inciuding about 8.1, 8.2, 8.3, 8.4! 8.5, 8.8, 8.7 or 8.8. Lignin is soiuble under ine ions and so standard bases, such as ammonia, which operate in the gen-erai pH 8.0 to 12.0 range are ideei for soiubiiising the iignin end are preferred herein. However, partial soiubiiity can be achieved with some tignin forms under miidiy acidic or neutrat conditions. Although ati of the iignin may not ve which may resuit in some granulation in the final coating it Witt be iated that it may be usefui in specific applications to create coatings of increased roughness for grip related advantages (such as compressive creep anaiysis for ng boxes in ohiiied or humid conditions) using this lower pH range. {0081] The coating step may be performed by firewoown coating, rod coating, spin coating, dip coating, Meyer rod coating, roller coating, spray g, brush g or air-knife coating. The spray and brush applications may be particuieriy suitabie for wood and wood veneer coatings.

Preferabiy, the coating step is performed by root coating as is oommoniy practised in the paper products manufacturing industry.

There are a wide range of coating methodologies and related technoiogy which are weil known in the art of coating with many commerciai solutions aveilabie. it is an advantage of the present invention that the coating compositions are suitable for use with standard industry accepted coating technotogies and so minimsi or no modification to existing hardware is required. {0084] The weight of the coating is between about “i to 35 GSM, 2 to 35 GSM or 5 to 35 GSM. ably, the weight of the coating is between about 5 to 30 GSM or 5 to 25 68M. in one embodiment, the coating weight is 6 to 35 683M, 6 to 30 GSM, 6 to 25 GSM or 6 to 20 {38M in a further embodiment, the g weight is 8 to 355 GSM, 8 to 3G GSM, 8 to 2‘5 GSM or 8 to 20 GSM. {0985] it is a further advantage of the present invention, and a resuit of the manner in which the process works, being that the g substantialiy remains on the externai coated surface of the substrate and does not to any extent resuiting in a functionai change to the substrate impregnate the substrate ai itself, that relativeiy iow coating weights are sufficient to achieve commercially useful water resistant andfor strengthening properties. in the exampies in W0 8141 the coating weights increase from 38 {35M to 281 GSM, and in one case the weight of the treated paper is sed by 70 “/9.

This is as a result of the different mechanism of action whereby WO 2000228141 ratios on substantiai impregnation of their composition into the paper artiste to achieve the desired improvement in strength. The present method empioys a typicai coating weight of iess than 20 GSM and does not reiy on, and in fact does not achieve, impregnation of the substrate to give the enhanced strength teristics. in one embodiment, the present method resuits in an increase in weight of the substrate of between 0.1 to 30%, 0.1 to 25%, (it to 20%, 0.1 to % or 0.1 to 10%. Common weight increases observed in paper substrates using the present method are between 5 % to ‘10 %. {0087] in one ment, the coating step is not performed under elevated pressures being those above heric pressure. The coating step is preferahiy carried out at atmospheric pressure. it is stiii a further advantage of the present inventive method that high pressures do not need to be generated for a curing step. Many prior art ses empioy such an energy intensive high pressure approach which requires additional infrastructure and so increases costs. The present method simpiy uses existing coating technoiogy under standard conditions to apoiy a simpie iignin solution to the substrate. {0088] The heat treatment is a thermal anneaiing to aiiow the iignin to undergo the required physical ormation to provide the waterproof g. {0089] For most iignins, and in particular those discussed above as suitable iignin sources for use in the present process the heat treatment is exposure to temperatures selected from the group consisting of temperatures greater than 70°C, 80°C, 90%), 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 180°C, 1?0°C, 180°C, "190°C, 200%, 210°C or 220%). An upper temperature iimit which may be combined with any one or' these lower limits to form a suitabie range would be the temperature at which the substrate becomes heat damaged or ignites. in one embodiment, this upper temperature iimit may be either 230°C or 240°C. in one embodiment wherein the lignin solution substantiaiiy comprises iignin as the oniy non—soivent component or comprises a, sugar or sugar alcohol, such as glyoe‘rot, and/or a ciser in less than 10% by weight of the iignin solution, the heat treatment may be exposure to a heat source at a temperature between about 160°C to about 230°C, preferably between about 170°C to about 230°C, more ably between about 100°C to 225°C. in one embodiment wherein the iignin solution comprises iignih and further comprises a sugar or sugar atoohoi, such as oi, at greater than %, preferabiy greater than 15% by weight of the lignin soiution, the heat treatment may be exposure to a temperature of n about 90°C to about 230°C, ably n about 100°C to about 230°C, more preferably between about 110°C to 225°C. {0092] The heat treatment, or thermal anneeiing, step is one potentiai route to a waterproof endior strengthening coating using the present method, the other being the acid treatment step. Without wishing to be bound by any particuiar theory, the inventors postulate that the i annealing and acid treatment steps represent a transition in the form of the iignin from a supersaturated state {giaas state) in the iignin soiution to e crystailine state {presenting a shiny finish on the substrate) and this can be achieved by either heating to suitebie temperatures or by rapidiy towering the pH. Thus, the two differing approaches of high temperature or acid treatment effectiveiy achieve the same outcome in terms of the criticei transition ofthe iignin. if this transition is not achieved then the coating wilt not he an effective waterproof barrier endlor wiii not provide the desired improved strength. For exempie, in testing when the thermai ing was carried out at iowertempereturee, without the addition of significant quantities of giycerol, then a coated paper with e powdery finish, which coutct be iargeiy removed by gentie rubbing, was formed This was not an effective roof coating and demonstrates that if the critical transition temperature (forthe thermal anneaiing approach) is not d then the iignin present on the ate cannot transform to become an effective barrier to water.

] For prior art references which employ iignin as a component in a waterproof coating the iignin cannot be contributing to the waterproofing properties to any significant extent unless a minimum temperature of t30°C, and preferably at (least 150°C (for coatings comprising tignin with iittie or no giyceml) or of 80°C, preferabiy 90%: (for coatings comprising iignin and cant amounts of glycerol as d above), is empioyeci or a: suitable acid treatment step is performed. The upper temperature limit is defined by the temperature which the substrate can withstand before becoming damaged. {8094] it is an advantage of the present invention that the heat ent step can be compieted in a matter of s when carried out in industrial heating equipment such as is ly empioyeci in paper making. in one embodiment, the heat ent step is compiete in iess than til min, 8 min, 5 min, 4 min, 3 min, 2 min, 1 min or 30 seconds.

The acid treatment may comprise contacting the iignin coating with an acid having a. pH below 4.0 or beiow 3.5. Preferehty, the pH is about 3.5 or beiow with a tower limit being 0 or 1. 2014/000987 {0096] The acid may be an inorganic {mineral) acid air an organic acid. it is preferred that the acid is a volatile acid. This allcws for the easy removal of the acid t leaving residues on the substrate or within the coating. Week acids are preferred. it is highly red that the acid is a velatile weak acids such as acetic acid. in one embodiment, the acid may be selected frcm the group consisting of acetic acid, formic acid, phosphoric acid and citric. acid. The acid may be diluted cr used neat. if diluted then a miscible solvent such as ethanol, ethyl acetate, glycerci or water may be used“ The choice of aolvent will depend on the subsequent exposure: of the coating to any naked flames during drying and the ensuing safety issues raised. in this regard, glycerol may have an advantage in reducing potential flammability“ {0097] When the iignin sotution fur the coating is a mildly acidic solution then it may be preferred that the treatment step is a heat ent (thermal annealing) step, as previnusiy described, rather than an acidic treatment. {0098] The acid may be sprayed onto the coating, or otherwise applied, to effect the transiticn in the ‘ to farm an effective roof barrier andr‘cr providing enhanced strength teristics. Particularly, the acid may be applied in an atomized spray which produces an even contact across the coated substrate surface such that no pcciing or run off ct acid is observed.

When the treatment is an acid treatment then the method may further include the step of drying the iignin coating. The drying may be under ambient ccnditicna or may e heating or reduced pressure. This drying step is simply tn remove-excess moisture and temperatures which wcuid induce thermal enneaiing are not necessary for drying. {00160} in embodiments, after the coating has dried the waterproof and/or thening coating comprises lignin as the major active waterproofing andior strength enhancing constituent. [001013 The dried coating may ccmprise greater than 60%, 770%, 80%, 90%, 95%, 96%, 97%, 98% or 99% by weight tighih.

WO 54736 {00102} in a preferred EMbOGimenL after the coating has dried the waterproof andi’or strengthening coating consists essentieiiy of iignin as the active waterproofing constituent. {091-03} in one embodiment, after the I‘ignin coating has dried the roof endfor strengthening coating oensists of iignin as the active waterproofing constituent. {(30104} As was described eariier, it is a unique advantage of the present. invention that an effective waterproof andior strengthening coating can be formed on a substrate pureiy by the use of iignin as the active waterproofing endfor strengthening component in the coating and; specificalty, by the transformation of the iignin to form a waterproof andlor strengthening coating by thermai anneeting or acid treatment. [001053 in certain embodiments, the iignin solution may be d with a neodonsing agent. The deodorising agent may be an oxidising agent or a suitabie absorbent. In one embodiment, the i’sing agent is selected from the group consisting of activated carbon, ozone, hydrogen peroxide, diatomeceous earth, activated clays, ion—exchange resins or siiica get. it may be desirable to have a deodorising agent, such as activated , when the paper product being coated is used for fond appiications. Lignin has an associated odour when d in a coating such as those described tly, in many appiications this woutd not present any ms but if the paper ct is in intimate contact with the food then it is possibie the odour may be imparted, to some extent, to the food. in such instances it is a simple matter of using a known deodorising agent to contact or pre—treet the lignin Composition.

The use of ted carbon in this manner is described in the experimentai section. {00106} in embodiments where the iignin sotution comprises a deodorising agent then it may be particulariy desirabie to acid a plasticiser to the soiution prior to coating. A piasticiser is 3130 usefui, as described eartier, in the WO 54736 2014/000987 embodiment wherein higher ol levels are incorporated into the iignln solution (10%, and above). By way of non—limiting example, the plasticiser may be selected from the group consisting of a natural or synthetic latex, e poiyezther, a glycol, a dioerhoxyiic or trioerboxyiio ester, 3 ate, an eikyl citrate and an acetyiated monogiyceride. Other commercially available plastioisere are well known in the art. it has been found that the use of deodorising agents! euoh as activated carbon, can reduce the natural plasticity of the lignin coating. To recover this loss in plasticity all that is required is the addition into the alkaline iignirr solution of a small quantity of a plasticiser such as a latex. A represe’nietlve amount for the ples’riciser would be n 0.1 to %, including 01. to 8%, 0.1 to 7%, 0.1 to {3%, Di . to 5%,0.1to 4%, 0.1 to 3%, preferably 1.010 5%, more preferably 2 to 4% and even more preferably about 2.5, 3.0 and 3.5%. of the coating composition. For most pleetioleers, such as latex, a range of ‘i to 8%, preferably 1.5 to 5%, more preferably 2 to 4% and even more preferably about 2.5,, 3.0 and 3.5% is appropriate. The amount required will depend upon the piaeticieing properties of the plesticiser used and can be determined by straightforward trials. it is important to understand that this relatively small amount of plasticiser does not substantially contribute to the waterproofing andror strengthening properties of the coating to any significant . That is, the plasticieer is not considered an active waterproofing andror strengthening component of the present compositions or . {0010?} A second aspect of the invention resides in a composition which comprises lignln, as the major active ent, at least partially dissolved in a solvent. [001-083 The composition may be as described for the first . Preferably, the solvent is an alkaline solution. {001 091 The alkaline solution, pH, Iignin type and source and other aspects of the composition may be as described for the first aspect.

WO 54736 {00110} The composition consists eeeentiaiiy of iignin, as the active roofing encii'or strengthening component. This means that it is the iignin which is substantieiiy responsibie for the waterproof andfor strengthening activity imparted by the composition. {00111} in a further embodiment. the waterproofing and/or strengthening composition consists of , as the active waterproofing and/or strengthening component. {001123 The composition may further oompriee or be contacted with e deodorising agent encifor e piestioiser, as described for the first aspect. {001’33} in one ment, the soivent is an aqueous ammonia solution. [001143 in one embodiment, the composition comprises between about 15% to about 40% by weight lignin and about 60% to about 85% by weight ammonia solution. [001153 in this ment, the composition. preferabiy comprises between about 25% to about 35% by weight iignin and about 65% to about "(5% by weight ammonia solution. {001161 in one embodiment, the composition further comprises and agent selected from a sugar and a sugar aioohoi Apecific exampies may be as recited for the first aspect. {001W} The sugar aicohoi may be a poiyoi, preterebiy oi, and may be present in a % by weight amount of the composition of between 0.1 to 35%. inoiuding CH to 30%, 9.1 to 25% and 0.1 to 20%. in one embodiment, the , preferebiy giyceroi, is present at 'i to 35%, inciuding '1 to 30%. i to 25% and ‘i to 20% or 5 to 35%, inciuding 5 to 3095‘ 5 to 25% and 8 to 20% or 8 to %, including 8 to 3B%, 8 to 25% and 8 to 20%,. in one embodiment, the poiyoi, preferehiy giyceroi, is present at 10 to 3.5%, insiuding to to 30%, 10 to % and to to 20%. in one embodiment. the polyol, ably giyoeroi, is present at 15 to 35%, inciuding 15 to 30%, i5 to 25% and “35 to 20%. 2014/000987 {00118} in one embodiment, the ition comprises the feilowing in % by weight amounts of the totai composition: (a) between abeut 10% to about 40% iignin; 6)} between about 35% to about. 80% ammonia solution; and (0) between about. 5% to about 36% at a sugat‘ or sugar aicohoi. {00119} ebty, in combinatien with any recited value of (b) or (c), the iignin is present in n about 15% to about 35%, more preferabiy between about 18% to about 30%, even more preferably between abeut 20% to about 27%. [001203 Suitably, in combinatien with any recite-d value at (a) or (c), the ammunia soiution is between about 40% te about 70%? preferehiy between about 45% to about 65%, more preferably about 50% to about 68%. {00121} ably, in combination with any d value of (a) or (b), the sugar er sugar aimhei is between about ’iD% to about 25%, mere preferabiy between about t5% te about 25%. [001223 Preferebty, the sugar or sugar aicohoi is as described for the first aspect, Meet preferebiy it is giycerol. {00123} in one embodiment, the cemposition further comprises a piesticieer as bed for the first aspect. Prefe-rabiy, the platsiciser is a iatex. {00124} in one embodiment, the eemposition comprises the piasticieer in e % by weight amount of between abOut 0.1% to 5%, preferably '1 13% to about 4.0% each of which ranges may be ed with any of those ranges cited abeve for (a): (b) and (c). {00125} in one embedim‘ent, the composition eemprises the foilewing in “/9 by weight amounts of the total compeeitien: {a} between about 18% to about 2T% iignin; (to) between about 50% to about 6?% ammonia soiutien; (it) between about 10% to abeut 25% glyceroi; and {d} between about 0.1% to about 4% iatex. [001283 in one embodiment, the pH of the composition is between about 7.5 to 95, ably between about 8.0 to about 9.0, {001327} in one embodiment, the composition wili have an oven dried solids content of between about 25 to 8,. preferebiy between about 27 to 40%DS. [001283 in one embodiment, the Brook’iield‘s Viscosity of the composition is n about ”£00 to 500, preferebiy between about 150 to about 400. [001293 According to a third aspect of the invention there is provided a use of the composition of the second aspect to form a meeting an a substrate. {00130} The ate may be as described for the first aspect. [001313 Such a coating is surprisingly water resistant andi’or will provide improved strength characteristics to the substrate, as wiil be seen in; the exempiesf given the fact that it is eniy lignin which is buting to any significant extent to the water ance endlor strengthening properties. [001323 The use wiii be as described, in each statement made in relation to the first aspect as if each of those statements was recited expiicitiy for the third aspect. {00133} A fourth aspect of the invention resides in a ate comprising a coating formed by the method of the first asbect. [001343 The waterproef ancifor thening coating may empioy the composition of the second aspect. [001.353 The substrate may be as described for the first aspect.

EXPEREMENTAL Gene-rat } Two different “grain-based fermuiations were generated for use in the toiiowing experiments. The first was a simpie acai iignin soiution LO} and the second was a simiiar ammoniaoai iignin soiution but which had been treated with activated carbon as a deodorising agent (LBCv’t .1 +AC).

} The foliowirig protocois describe methodotogy to create formulations of a Specific target viscosity (ca. 10904200 mPas) within the iaboratory by batch in open vesseis. This was achieved by first evaporating in an open beaker to a concentrated state (Viscosity greater than as — overshooting the end point — higher viscosity and tower pH) and then adding a to adjust ‘up’ to a target pH (8.4-5). By making the tormutation in this manner it is possibie to consistentiy achieve the target viscosity. {00138} While this approach is suitabie torthe iaborstery it may be preferable at seats to emoioy the use of iarge stirred and heated reactors and partiai vacuum (124:6 mm Hg) to rationalise the formuiation creation process _ Le. evaporate under partiai vacuum (and tower temperature) in a dosed reactor system to an end point. Through this work it has been determined that a wide range of viscosities (as tow as 80 mPas and as high as 4000 mPas) of aikaiine iignin solution Witt stilt act to form an effective barrier titm if appropriately annealediacid treated.

Pregaration of LBCv'i .0 {001.393 Weigh raw lignin (290g) and add a solution (1 L 0.5 M NHg) into a vessei at ieaet twice the. finai expected volume (to allow space for initiai foaming), creating a ca. 300 g ligninlkg 0.5 M NHg solution. Mix by overhead stirring using biacle attachment at high speed (ca. 800 rpm) untii formuiation is homogenous. Reduce ng speed (ca. ZGD—SODrprn) and blend (either by magnetic or overhead stirring) within the vessei d to ambient Conditions and heated at 80°C (by heating piste) for ca. 24hrs. Post 24hrs measure the pH of the formuiation. it“ pH is greater than 7.2 onntinue stirring and k every 1—2 hours. Once pH approaches neutrai (ca. 7.2), fonnuiation will begin to thicken and appear “toffee like”- This change may be rapid. {00140} The Brookfieids Viscosity (BrViS) of a subsampie should then be measured to confirm if it is greater than 2000 mPe.e. if EMS is too tow continue stirring and subsempie every hour untii BrVis within range (>2000 mPes). Once formulation is within range ediuet the pH to ca. 8.445 with neat NHS %).

Check the BrVis which should be in the range of woo—12:00 mPe.s at this pH {60mm spindle 3). This is the final tormuietion (LBCV‘I .0) which may be sealed and preferably refrigerated until usage. Prior to usage ensure pH is within preferred range {pH 8.4—5) and adjust if ed (28% NHS). Check finei EMS- is within range (10004200 mPee). {00141} Note that foaming may be managed with the on of iised ethane! or defoemer as required. Optioneily, end as discussed above, the reaction may take piece in a seated vess‘ei capabie of drawing a partial vacuum (approx 124 6mm Hg) to remove volatile gases produced during stirring. ln addition the required stirring time at 80°C can be significantiy shortened using a partial vacuum to under 2 hours. ments have shown a greater range of pits (ie. iees than 8.4»85) and tower viscositiee (ie. lower than 1000—1200 cps) also form an effective fiim and provide good water barriers so long as they are appropriately annealed. ation of LBCv’t .1 +AC {001421 Weigh e voiume of Activated Carbon (AC) approximately to “US (or as tow as M?) of the expected total finai formuiation voiume and record weight (ie. if creating 1 kg of formulation piece 333mL of AC into a percolation coiumn and record dry weight (ca. t65 9)). Wash AC with boiiing- miiiiQ H20 {8.45pm fittered) and decent fines- Repeat untii runoff from AC is clear. Drain as much milliQ H20 as possible and transfer into a ore-weighed percoiation coiumn or iike vessel- Caiouiate wet AC weight and determine amount of d and bound H20 (eg. if final wet AC weight is 403 Q then trappeoifbound AC H20 is ca. 238 g). Create a soiution ( 0.5M nil-l3) taking into consideration the trappedlbound AC H20 (eg. if 433 g) and reduce volume accordin-giy (eg. 33.8 mi. (28% NHS‘) in 59? mi. miliiQ H20, total volume inciuding trapped/hound H20 is tDQOmt. for target moierity of 0.5M NHB). {00143} Weigh lignin (296 g) and add ammonia solution (597 mi. of {21.5 M NHE, as described above) into a formuietion vessei at. iesst twice the finai expected volume (to eilow for l foaming). Mix by overhead stirring using blade attachment at high speed (ca- 500 rpm) untii ation is homogenates.

Reduce stirring speed (ea 100200 rpm). Circuiete lignin ammonia solution through the AC perooiation column and return outflow to formulation vessel.

Continue circulation and overhead stirring using paddle attachment with the vessei exposed to atmospheric pressure and heated at 80°C (by heating plate) for ca. 3 hrs. The AC may be added into the aikaiine a soiution itseii but it is preferred that the column approach described be employed. [001443 Remove subsampie and attow to cool to ambient temperature. Spot check for odour removal by nose and comparison to i formulation. if not deemed satisfactory continue AC column treatment and repeat spot check in 30 min intervals. Once satisfactory. remove from heat and stop treatment. [001453 Blend formulation (either by magnetic or overhead stirring) within a vessei exposed to ambient ions and heated at 80°C (by heating piste) for ca. 20hrs. Post 24hrs measure the pH of the formulation. lf pH is greater than 7’2 continue ng and recheck every 1—2 hours. Once pH approaches neutral (ca. 7.2), formulation will begin to n and appear ‘toftee like’. This may be quite rapid. {001463 Measure the Brooid’ields Viscosity ) of a subsemple and confirm greater than 2000 mPes. if BrVis is too low ue stirring and subsempte every hour untii BrVis within range (>2000 mPa.s). Once formuiation is within range cooi to ambient, adjust the pH to ca. 8.4-5 with neat NHS (28%).

Check the BrVis which should be in the range of 1000—1200 mPes (BDrpm, spindle 3). This is the final ton'nuiation (LBCvt .‘i +AC) which shouid be seated and preferably refrigerated untii usage. Prior to usage ensure pH is within range 2014/000987 (pH 8.4-5} and adjust if required (2895* NHS). Fineliy, check final BrVie is within range (1000—3200 mPae}. {00147} As discussed for the LBCv’i .0 formulation, foaming may be managed with addition of eerosolised ethanol or defoamer and the reaction may optionally take place in a sealed vessei capable of drawing a partial vacuum {0a. 12—16mm Hg) to remove volatile gases produced during ng. Once formulation is blended vacuum is switched off and formulation passed through 3 GAO column for ca. 2-6 bed volumes with GAG treated formulation subsampled and tested by noise until odour in ly reduced. Vacuum is then resumed until ation is ready. Once again, experiments have shown a greater range of pH’s (ie. less than 8.4—8.5) and lower viscosities (ie. lower than 1000—1200 ops) also form an effective coating which provides good water barriers if appropriately annealed.

Thermal in Ex erim‘ents [001483 Atempereture annealing series using the above standard (LBle .0) and deodorised l .1 +AC) formulations (both pH 8.4-5 BrVis 1000—1200 — Brnokfield viscometer 1000 to 1200 op) coated onto Kraft 205 paper on the shiny side by drawdown coater was performed. {00149} For the 0 the coating application wee Rod 0 + Rod 9 on a drawdown ooater for annealing temperatures 39% (preconditioning oven and max thermal treatment for room temp samples) and then 100°C to 220°C {in °C intervals). Ali paper used in the experiments was preconditioned by heating at 39°C prior to coating. The duration of the coated samples within the oven was 90 s after the rod 0 application and 5 min after the second g application (Rod 9). Therefore, the totai annealing duration was 6 min 30 s. {00150} For LBCv‘l.‘l+AC the coating application was Rod 0 + Rod 9 and Rod 0 + Rod 6 for annealing temperatures 160°C to 220%: (in ’lO“C intervals).

As above, the duration within oven was 90 s for Rod 0, 5 min for second ation (Rod 9 and Rod 6). Tote! annealing duration 6 min 30 s, {00151} The results of these experiments are presented in tabie *‘l, beiow, and are shown graphioaily in Fle 1 (LBCv‘l .0) and 2 (LBCV1.1+AC), Control measurements in the results are from paper that has been through the heat treatment without being coated with any formulation.

Cobb (33min) 91mg ion (“1%) rel. Ctl.

Temp “ Rod 9 Rod 9 Rod 5 Rod 9 Rod 9 Rod 6 wehm m m m m zoo 28.0 2w 28.6 Tobie ’3: ison of Cobb (30 min) for typical (LBCv’l .0) and deodori‘sed {LBCV‘I .'l+AC) f’ormutations at a range of ing temperatures.

Coating Weight Exgeriments {00152} A oompiete coating weight series was performed using the standard formulation (LBCv‘i ‘0, p‘HStii—S, BrVisi 000—1 200) d onto K205 shiny side by a drawdown mater. Application was Rod 0 which was flashed for 90 s at 220°C followed by Rod 0 to Rod 9 thermally anneated for 5 min at 220°C. The total annealing on was therefore 6 min 30 s. A rod 0 coating was also made by itseif (ie. no subsequent. coating) and annealed for 5 min at 220°C.

The s of these experiments are presented in tabis 2, beiow, and are shown graphicsiiy in FEB 3.

Coating snub ion Boating Method 30mm Inn? (A) rel. (ca GSM) Ct! R0 5 minm—’— some R0+R2.m RU+R3 Rams Rams R0~+R8 ; RD+R9 Ci! 5 min) we5 mm) Tobie 2: Standard formuiation (LBCvi 0 pH 845 BrVis “£0001200))on K285 shiny side appiisd at different coating weights (Rod 0, Rod 0 + (Rod 0 — 9)).

Experiments with Activated Carbon and P‘iasticiser [001533 The iignin pius ted carbon composition was used to assess ihe effects of oiasticisers on coating. The ciser used was naturai istex (LaN) addeo by 94') weight (0.5, 1.0 and 2% (wiw)). The compositions were coated in dupiicate by drawdown casting onto K205 shiny side through appiication of Rod 6 {5 min) foilowed by Rod o (90 s) and smeared at 220°C, A summary of selected resmis is inciuded in table 3.

Sampie . _ Odor - Ranking wm-m_—---—- Lignin +GAC + 1 % 85 LaN 1945 Lignin +GAC+ 2 % Lam-128_480560_520 Tabie 3: Lignin +GAG in Piasticizer investigation with Nature! Latex (LaN) addition.

Acid Treatment Exgeriments {00154} An acid treatment using a deodorised (LBCV1.’E+AC)formulation with 2% natural latex (Wr‘w), coated onto Kraft 205 paper on the shiny side with a singte Red 6 applicatien by drawdewn water was performed. [001.553 i acetic acid was appiied evenly to the iignin coated substrates using an atomized spray te obtain even contact across the surface with no pooling or run off. it has been. feund that acetic acid which iedituted in a y ef miscible vetatiie solvents» such as ethanei or ethyl acetate may atso be siueceesfuily used. Water and giyce‘rol is also vsuitabie. {09156} Pest acid applicatien the treated substrate was even dried at ‘i 10°C for five minutes te speed up residual mdieture removal. it has been observed that leaving treated samples in a well vented area such as a fume hand has a camparabie effect but takes . 1 A comparison between coated substrates with surfaces d with acid (5 min: “i 00 °C), without acid and mating dried (5 min, 100 °C), and without acid and g anneaied (5 min, 220 °C) are ted in Tabie 4, below.

Centre! measurements in the resuits are from paper that has not been through any heater acid treatment and without being coated with any formuiation.

Transfer Sampie Cobb (30 min) (glmg) Odor Ranking Rankin ; Lignin + Acid (100 % (3AA) Licnin+ e in “0°05 min Linin + Anneai (220 WC; 5 min Uncoated Control Tabie 4: Lignin in Acid Treatment investigation {09158} Sampies treated by acid produced a surface that did not easily er pest protenged water contact {30 min) and a Cebb vaiue comparable to industry standards such as SuperVisy, whose performance is ca. 87 g/m2 by WO 54736 Cobb (30 min) enetysie. it is believed that further optimisetien of this acid treatment process can produce further improved Cabin venues.

Anneeiing Using Lignin Formulation with Activated Carbon (ACE and Latex {00159} Using a deedorieed formulation of lignin with granular activated carbon (GAD) treated with e i tatex piastieizer {+ 2% iLeN) at appropriate ity (BrVie 620 — 820 (mPaej) e fut! annealing duration investigatien was ted. {00180} Samptee were coated by drewdown coating ante. K205 Shiny tine-r heard by application ot'Red 6 for 5, 4 and 2 min toiiowed by Rod 0 for 90 s at 220, 200 and 180°C thermei enneeiing conditions (for a total of 6.5, 5.5 and 3.5 minutes treatment tively). A singie Red 8 + Rod C (5 min, 90 s —- 160 deg) and Red 1 + Rod “i (2 min, 90 e _ €50 deg) were created as exampiee ef ‘woret cese’ temperature profites. A summary of the resuits is included in tabie 5 and represented grephicetiy by the surface plot in HS 4.

Anneeiin Temereture .gde Cent) (30 min) ) Tebte 5: Lignin + GAG + LaN {2%)in Anneaiing investigation- Cobb (30 min) data summery {00181} A goed outcome from such a triai is a surface that achieves a barrier coating of tees than or equivaient to industry representatives, such as SuperVisy, whose performance is ca. 87 glm? by Cobb (30 min) anatysisr it can be seen that the present coatings perferm better than comparative rds and vaiues within the green range of HS 4 (Cobb (30 min) of 4D » 65 (91mm) are obtained which is censidered entative of an excellent waterproof coating. It is onty when anneaiing temperatures drop beiew 160°C that values reach what is shown in FIG 4 to be the red zone enting a coating which Wfiuid not be cemmerciatiy desirabiei Exgeriments with Lignin Seiutien at Nonetkaiine QH {00162} Mix 13.00 g of NH3 (30 0/0) with 433 g 0! H20 creating a 0.4 M NH3 solution into an ambient reactor. Blend with 135.19 iignin fortotei tormuiation of 558.9 g and a tins! target dry sotids of (96053) of 22.66. The target dry sotids (%DS) quoted compensates for the moisture content of the ng itgnin. in this case the tignin moisture content used was 6-3 %. [001833 The sample displayed a pH of 7.1 and had a viscosity of BrVis 80 n 100 mPas. The sampte was stored for 2 days and itwes found that the pH had dropped r to 8.9 (ambient) and smelt iignin ates had formed. it was obvious that some iignin had dropped out of soiution, likely due 0 the now mitdiy acidic pH, and was in a suspension state, [(301643 ln terms of mance the pH 6.9 formulation was coated onto Kraft tinerheerd (K205) along with two similar formutation samptes but where the pH had been adjusted back ‘up’ to 7.? and 8.8. Ait samptes were annotated at 231°C after coating. The results are shown in tabie 6. [001853 All coatings created a substrate that looked good, but had a higher friction surface instead of a standard smooth gtoss. This woutd Iik‘eiy be dueto the use of a formulation in which the lignin was only pertiatiy soiubiiiseti Cobb values improved as the. pH increased, and usefut water barrier properties were ed. This indicates that eithough an aikaline iignin solution is preferably ed as the coating composition, a usetui waterproof coating can be obtained even when a mitoty acidic ttgnin solution is the starting point so tong as the subsequent treatment, in this case a heat treatment, achieves the required transition of the al form of the .

BrVis Sotids mPes (V005 teen 0 . pHBs LBCW 0 pH?7)“-m- LBCW0 H88 Tabie 6: Cobb values for coatings formed using lignin coating composition of varying pH values. 2014/000987 Pregeration of ised ation at Scale {00166} Activated carbon column is firstly prepared as follows: “i. Fill with 375 kg of granular activated carbon and seal flange lid. 2. Change with hot water (water & steam) with top vent open, until full. 3. Close top vent and purge with hot water until no more air bubbles are in the discharge. 4. Remove flange lid, drain to surface of carbon (ensuring carbon is covered with water at all times), and leave overnight. Column will have to be ore—heeled prior to. use. {0018?} The alkaline lignin coating solution is then prepared as follows; i. Add 2.5 tonnes of water (deionized (Di) or reverse osmosis (R0) treatetl if possible — should be ca. pH 5.5) to the reactor at t temperature. 2. Add 100 kg of aqueous ammonia (it it is 30 % ammonia) while ng at ambient temperature. The vacuum will be on and the condenser recirculating (reflux) into the reactor. 3, Begin heating reactor and blending l tonne of lignin. Approximately ‘lO L of ethanol may be required to reduce g. 4, Close reactor and heat to 85 - 95 ”C until lignin is dissolved (continue reflux conditions).

. Circulate iignin solution through activated carbon column. Column can he topped up with formulation with top valve open to fill heedsoace with minimal disturbance of carbon bed. Then close top valve and begin flow through operation while taking initial water discharge (the column void) to waste. As the lignin ation breaks through (not initial color change, but when output from column is comparable in viscosity to inlet — this can be tested by touching ation with gloves and comparing resistance to pulling thumb and forefinger apart e we can assist with this stage) divert the discharge from waste to the reactor. Ree—circulate 4 to 5 reaction volumes (lZGOD l. to lSOGO l.) of formulation through the column. Then open top valve and drain ing liquid in the column into reactor. 6» Reduce the femuletion voiume under partial vacuum until it reaches a desired room temperature viscosity. [001683 The above experimentai approach wiii provide deederised ations without piasticiser which are appropriate as inputs tn the next stage of seating foilowed by heat treatment or acid treatment to obtain a waterproof coating. Alternativeiy a plasticieer may be added after step 8 upon erring the compositien into an appropriate storage container, This methodelogy wiil be a practical approach for producing ation at the scale required for industrial application.

Reduced Tern erature and Gelatin Wei ht with Hi h GE cerol inciueion [001693 A ‘iew thermal see formulation’ {LBCVBD i(20P/3)) (53.1% H20, 25% Ammenie (25%}, 3% Latex (819608), 20% Glycerol, 21.4% Lignin ail w/w) of Broekfieid’s Viscosity 180 — 320 (WIPES), pH 8.3-5, and oven dried solids of 32 - 34 %DS "was coated onto Kraft liner board (ca. 185 GSM) shiny side by drawdown caster. Application was in a single coat, Rod 1' to Rod 8, duration within annealing oven was 5 min, for temperatures 140, 130 and 180°C. Cobb values of the resulting substrates are shown beiow in table 7 and are represented caiiy in HS 5.

D{2?')+PE(2OP/3) Cobb 30 min {gimfiZ} : 1 Application Ce. Coating Annealing Conditions (“Ci Method Weight 5 I (GEM) 140 160 180 dontrotifirafiias") ' +Pl (20P13)) formulatien, seated on Kraft 185 (ca. GSM) linear board on the shiny side at a range of anneaiing temperatures and coating weights, Hi her Tern erature and Coatin. Wei htwit‘h Reduced GI ceroi Level [001703 A ‘high thermal optimised formulatien’ {LBCVSIJ (27}+P3(1012)) (80.4% H20. 2.9% Ammunia (25%), 2% Latex (81%;08). 10% Giycer’ei, 24.7% Lignin all wfw) of Brookfieid’s Viscosity 380 — 500 (mPa.s), pH 8.8—9, and oven dried solids of 33 — 34 %DS —was seated onto Kraft iiner board (ca. 205 GSM) shiny side by wn caster. Appiicetion was either single or a double coat, Rod “l, Rod 1 + Rod ”l, Rod 6, Rod 6 + Red 1, Rod 6 + Red 6, duration: witi'iin annealing OVER was 5 min for all Rod 8 ations and 2 min for Rod ‘3, for temperatures 160, 180 and 220°C. Cobb values of the resuiti'ng substrates are shown below in table 8 and are represented graphically in FiG 6.

LBCVS.0(27)+Pl(10l2) Cobb 30 min (glm2) Application 112a. CoatingW Method Weight (88M) 160 180 220 Control (Kraft 205) 110.4 105.1 94.5 R1 241 112.6 105.1 90.0 meat 4-? 914 88.4 48.2 as 12-18 45.8 22.5 3.7 Rs+a1 1 16—23 19.8 33.2 4.4 R6+R6 I 213-313 16.3 so 1.6 Table 8: Comparison of Cobb (30 mimicr‘ high thermal optimised (LBCVSfl (2?) +P‘l (1012)}iermulation, coated on Kraft 205 (ca. GSM} linear board on the shiny side at a range of annealing temperatures and coating weights. 90°C Temgereture ent and ed Annealing {001?11 Using the same tow thermal optimised farmulation as prepared for the reduced ature and coating weightannealing series (LBCV3.U‘ i {ZOPISD (53-1% H20, 2.5% Ammonia (25%), 3% Latex (619/008), 20% Glycerol, 21.4% Lignin ail MW) of Brookfieid’s Viscosity 180 — 320 (mPas), pH 8.3—5, and oven dried solids of 32 — 34 %DS. A Kraft liner board (ca. 185 GSM) was coated shiny side by drawdown coater (Rod 7) in a single coat application and annealed within an oven preheated to 90°C for 3 hours. The anneaied coated substrate displayed no transfer oftha coating post heavy rubbing and achieved a Cobb (30 min) of 72.7 (grin?) compared to a Cobb (30 min) of 90.9 for the unooated control of the some substrate thermaily treated in the same fashion demonstrating an increase in iiquid water barrier performance.

Annealing Duration Exgeriments {00172} Time triai optimised formuiation (LBCVBG (2'9) + Pl (209%)) (51.3% H20, 2.7% a (25%), 3% Latex (619608), 20% Glycerol, 23.0% Lignin all wfw) of ieid‘s Viscosity 800 ~ 900 (mPas), pH 8.1—8.9, and oven dried solids of 38 —« 40 %DS. A Kraft liner board (ca. 185 GSM) was coated shiny side by drawdown coater (Rod 6) in a singie coat ation and annealed within an oven preheated to 180°C for 0, 0.5, “i, 1.5, 2., 5, i“ and ‘30 minutes. The results are indicated in table 9 and HQ 7. } in the iaboratory‘ scaie ovens used, the ate required ca. 3 min for the coated surface to reach the target annealing conditions (180°C). This is also the apparent point of l performance in terms of anneaiing duration with limited mance increase for extended durations tested. it is appreciated that in commercial scale heating equipment, the time required for a substrates e to reach the target anneaiing conditions wili be for quicker and typicaiiy in the order of seconds.

Liquid Water Barrier Annealing Duration {min} @ 180°C (Cnbb 30 {min} {gfm2)) 2 3 5 LBCV3.O(29)+PI{20P,' P18 37 91 as 5_S Rod 6 29 19 9 10 13 12 Uncoated Control (OHPISS) 91 37 83 84 82 79 76 75 73 *‘0' min = No Anneaiing treatment and ambient drying {23 deg. 50% RH). Max thermal treatment at 37 deg during rd preconditioning.

Tobie 9: Comparison of Cobb (30 min) for optimised (£80130 (29’) +Pl (EDPi’SD formuiation, coated on Kraft 1.85 (ca. GSM) linear heard an the shiny side with varying annealing duration.

Formuietinn of rmalO timised Permutation LBCVSfl 217 +Pi ZOPIB [001?4} into ambient reactor {screw top eyer ‘— SOBmsL) add 132.75 9 Di H20 and 6.28 g at NH3 (25 iii). Mix by gentie swiriirig creating a 0.68 M NHE, solution. Further acid 35 g of iatex (Si %DS) and 50 g giycerol. Place reactnr into Gyratory Water Bath Shaker and start heat (high) with set point 90 deg and arbital agitation (low speed). Biend with 53.4? g of sieved {’GUOum) raw iignin P81 k (13) 2.8 %MSTR) fur a total formuiation {if 250 9'. Continue untii homagenaus and internai formuiatian above 80 deg (ca. 1-2 hr). Sieve (BOUpm) white hat, Vmininn fines shouid be present. ation 0f Hi h Thermal O timised Formulation LEG/3.0 27 +Pi 10.32 i [001753 into ambient reactor (screw top eyer - SUOmL) add 151.0? 9 Di H20 and 7.24 g of iii-13 (25 926), Mix by gentie swiriing creating a 0.7 M NH3 solution. r acid 5 g of iatex and 25 .9 glycerol. Piece r into Gyra‘tory Water Bath Shaker and start heat (high) with set point 90- deg and orbitat agitation (iow speed). Blend with 61.88 g of sieved (600nm) raw lignin PB‘lk. (13) 3.7 WaMSTR) for a total formuietion of 250 g. Continue untii homogenous and internal formulation above 8-D deg (ca. ”3-2 hr). Sieve (600nm) white hot, no fines shnuid be present.

Formulation for Reduced Temgereture Annealing (LBCVSD {29) + Pi i‘ZOPIS); {001763 into a reactor add 900 kg of water (deionized) and 54 kg of aqueous ammonia {25 % NH3) white stirring at ambient temperature. Add 50 kg of nature! iatex (6i %DS) and ue stirring. Add 400 kg of Giycerol (BF), continue stirring. Begin heating reactor to 50%: and begin adding lignin 460 kg of raw iignin PBik (13) (2.8%MSTR).Wash the inside of reactor waiis with a further 127 kg of water {deianizedi Cieee reactor and heat to greaterthen 80°C. and then continue to stir for at ieast 1 hour under reflux. The fine! formulatinn shoutd be ca. 38 — 40% [38, pH ca, 8.1 to 8.93mi Brookfieid’s viscosity of 600 - 900 GP at ambient (ca. 23 deg). {00177} The results shown for the experiments using 20% and 13% of glycerol, respectiveiy indicate the success of the approach whereby giyceroi is used to achieve similar Cobb values with a reduction in the required anneaiing temperatures- Thus, while the use at giyeeroi is not essential to the present invention it is preferred in terms of the reduced temperature requirement and the quaiity of the waterproof fiim that is formed. [001783 The present invention thus provides for exoeiien’r quaiity roof an'dior strengthening coatings based on itions which contain oniy iignin as the sole active waterproofing andfor strengthening agent. The transformation of the iignin into a preferred state: which provides surprisingly effective roofing and/or strengthening ties on the substrate is achieved by either a thermal annealing at temperatures above about 160°C or by an acid ent step. Such a simple ation is easiiy handied, requires minimai manipulation: in terms of optimising pH, Viscosity and the iike and is eiy cost ive due to the simplicity of the active ingredients and the wide avaiiabiiity of iignin. {00179} The above description of various embodiments of the present ion is provided for purposes of description to one of ordinary skiii in the related art. it is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. Acmrdingiy, while some alternative embodiments have been discussed specificaiiy, other embodiments wili be apparent or reiatively‘ easiiy ped by those of ordinaryr skiii in the art. Accordingiy, this patent speoification is intended to embrace al‘i aiternattves, modifications and variations of the present invention. {00180} in the claims which toiiow and in the preceding description of the invention, except where the context cieariy requires otherwise due to express ge or necessary impiication, the word “comprise”, or variations thereof §nciuding “comprises” or “comprising",_ is used in an ive sense, that is, t0 specify the presence of the stated integers but without precluding the presence or addition cf further integers in one or more embodiments of the invention.

Claims (20)

1. A method of forming a coating on an external surface of a formed nonmetal substrate including the steps of: (a) forming a lignin on, n the lignin is the major active waterproofing and/or strengthening agent, by at least partially dissolving a lignin in an alkaline solution; (b) g the lignin solution onto the external surface of the formed non-metal substrate; and (c) exposing the lignin coated substrate to a treatment selected from the group consisting of a heat treatment at a temperature of between 120°C to 240°C and an acid treatment, to thereby form a coating on the al surface of the formed nonmetal substrate.

2. The method of claim 1 wherein the ate is selected from the group consisting of lignocellulosic substrates, lignocellulosic derived substrates, cellulosic substrates and cellulosic derived substrates.

3. The method of claim 1 or claim 2 n the alkaline solution is an a solution.

4. The method of any one of the preceding claims wherein the lignin solution consists essentially of lignin as the active waterproofing and/or strengthening agent.

5. The method of any one of the preceding claims wherein the % by weight amount of lignin in the lignin solution is between 10 to 40%.

6. The method of any one of the preceding claims wherein the lignin solution further comprises a sugar and/or sugar alcohol.

7. The method of any one of the preceding claims wherein the lignin solution further comprises a plasticiser. 3238217v1

8. The method of claim 7 wherein the lignin solution ntially comprises lignin, glycerol and the plasticiser as the only non-solvent ents.

9. The method of any one of the preceding claims wherein the pH of the lignin on at g is between about 7.0 to 9.5.

10. The method of any one of the preceding claims n the acid treatment comprises contacting the lignin coating with an acid having a pH below 4.0.

11. The method of any one of the preceding claims wherein the lignin is not a lignosulfonate lignin from sulfite pulping.

12. A method of forming a coating which remains on substantially only an external surface of a formed non-metal substrate including the steps of: (a) forming a lignin solution by at least partially dissolving a lignin in an alkaline solution, wherein the lignin is not a lignosulfonate lignin and wherein the lignin solution comprises lignin, glycerol and a plasticiser; (b) coating the lignin solution onto the external surface of the formed non-metal substrate; and (c) exposing the lignin coated substrate to a ent selected from the group consisting of a heat treatment at a temperature of between 120°C to 240°C and an acid treatment, to thereby form a coating which remains on substantially only the external surface of the formed non-metal substrate.

13. A composition which comprises: (a) an s alkaline solution; (b) lignin, as the major active roofing and/or strengthening agent, at least partially dissolved in the aqueous alkaline solution; (c) a sugar and/or sugar alcohol; and 3238217v1 (d) a plasticiser.

14. The ition of claim 13 wherein the composition consists ially of lignin, as the active waterproofing and/or strengthening agent.

15. The composition of claim 13 or claim 14 wherein the aqueous alkaline solution is an aqueous ammonia solution.

16. The composition of claim 15 wherein the ition comprises n about 10% to about 40% by weight lignin and about 35% to about 85% by weight ammonia solution.

17. The composition of claim 16 wherein the composition comprises the following in % by weight amounts of the total composition: (a) between about 10% to about 40% lignin; (b) between about 35% to about 80% ammonia solution; and (c) between about 5% to about 30% of a sugar and/or sugar alcohol.

18. The composition of claim 17 wherein the composition ses the following in % by weight amounts of the total composition: (a) between about 18% to about 27% lignin; (b) between about 50% to about 67% ammonia on; (c) between about 10% to about 25% glycerol; and (d) between about 0.1% to about 4% latex.

19. A use of the composition of any one of claim 13 to claim 18 to form a coating on an external surface of a non-metal formed substrate.

20. A non-metal substrate comprising a coating formed by the method of any one of claim 1 to claim 12. 3238217v1