SE545296C2 - Fluorocarbon free and biobased oil and water barrier materials - Google Patents

Abstract

The present invention relates generally to compositions comprising polyelectrolytes complexes (PECs) of anionic and cationic biopolymers capable of forming barriers on fiber based materials. Also disclosed is a fibre based material with a barrier coating against oil and water, wherein the material is provided with a barrier from at least two layers formed from at least one composition comprising a polyelectrolyte complex (PEC) of a cationic biopolymer and an anionic biopolymer, The two layers result in improvements in both oil resistance and water resistance compared to the same material provided with a single layer of said at least one composition.

Description

FLUOROCARBON FREE AND BIOBASED OIL AND WATER BARRIER MATERIALS Technical field id="p-1"

[0001] The present invention relates generally to compositions comprising polyelectrolytes complexes (PECs) of anionic and cationic biopolymers capable of forming barriers on fiber based materials.

Backqround of the invention id="p-2"

[0002] ln order to increase oil and water resistance on fibre-based materials (create an oil and water barrier), for example papers for paper packaging, it is common to coat these with different polymeric materials. Today, almost exclusively polymers from fossil sources are used such as polyethylene. ln some cases, plastic is also used in combination with aluminium foil to get stronger barriers. Fluorocarbons are also very efficient chemicals in making fibrous materials oil and water repellent but more and more fluorinated compounds are banned all over the world due to their toxicity and bioaccumulation. Today the packaging industry/paper industry, amongst others, is seeking for new sustainable solutions to create oil and water barriers which meet the standard of being non- toxic, bio-based and biodegradable. id="p-3"

[0003] As awareness of and demand for bio-based materials increase, interest in finding substitutes for the fossil-based barriers also increases. ln the food industry it is particularly important to find bio-based substitutes for conventional barriers, since there is a special focus on the recyclability of the packaging material. Also, the packaging industry has a demand for biodegradable barriers since compostability is a major challenge for single use items. id="p-4"

[0004] PECs are the association complexes formed between oppositely charged particles such as polymer-polymer, polymer-drug and polymer-drug-polymer. These complexes are formed due to electrostatic interactions between oppositely charged polyions and thereby avoid the use of chemical cross linking agents.

Based on origin polyelectrolytes are classified as natural, synthetic and chemically modified biopolymers. id="p-5"

[0005] US Patent 8,747,955 discloses methods of producing food packaging with fat barrier by means of coatings comprising a polyelectrolyte complex from anionic and cationic polymers, such as synthetic polyacrylates and polyacids. lt would however, be advantageous to find suitable biobased materials that could form similarly useful barrier coatings from polyelectrolyte compositions. id="p-6"

[0006] WO 2018/038671 describes compositions of polyelectrolyte complexes from biobased oppositely charged polymers that are useful as binders for fiber based materials, textiles, woven and nonwoven materials and induce improvements in material strength. id="p-7"

[0007] lt would be desirable to further develop PEC compositions derived from biobased charged polymers to obtain compositions that can be used to obtain controlled barriers of biodegradable fiber materials, both for fats, grease or oils and for water based systems, especially, but not limited to, for the purpose of protecting food products. For a person skilled in the art it is obvious from common knowledge that a water and oil repellent barrier material is also useful for dirt repellency where applicable. lt is also further understood that an increase in oxygen barrier is achieved with these kinds of barrier materials. id="p-8"

[0008] Previous experience using bio-based binders has led us to the use of starch and, specifically the use of cationic starch for creating a sustainable highly efficient barrier for oil and water. The knowledge that polyelectrolyte complex (PEC) brings synergistic effect from cationic and anionic polymers led us towards testing the combinations of cationic starch (CS) and sodium carboxymethyl cellulose (CMC) and synergistic effects towards achieving an oil and water barrier were discovered by layers of two or more.

Summary of invention [0009] lt is a general object of the invention to use hydrophilic biomaterials to form barrier structures useful against both oily products and water or water based products. id="p-10"

[0010] lt is an object of the invention to provide compositions of hydrophilic biomaterials that can form several layers on fiber based materials so that the layers can act synergistically to improve both oil and water barrier capacity of the material with its applied layers. id="p-11"

[0011] lt is a specific object of the present invention to provide fiber based materials with an oil and water barrier from compositions of a biodegradable polyelectrolyte complex from cationic and anionic biopolymers comprising only components and additives generally approved to be used in food contact. id="p-12"

[0012] srš lt is also an object of the present invention to obtain oil and water barriers with controlled tackiness of the applied barriers and thereby high resistance to disintegration or dissolution of the barrier while still controlling heat-sealing ability. id="p-13"

[0013] ln one general first aspect, the invention is directed to a fiber based material with a barrier coating against oil and water, wherein the material is provided with a barrier from at least two layers formed from at least one composition comprising a polyelectrolyte complex (PEC) of a cationic biopolymer and an anionic biopolymer. The presence of the two layers is synergistic and resuits in improvements in bstn ett resistance and water resistance compared to the same material provided with a single layer of said at least one composition. The meaning of the term improvements in this aspect is that for the material, an increase in oil and water resistance shall be significant and observable with standard tests, such as the KšT test according to T 999 pm-96 for oil and the COBB method according to ISO 536:191 (E) for water. id="p-14"

[0014] A fiber based material in the meaning of the present application may generally comprise synthetic or biofibers such as fibers of celluloses, polymer fibers or mixtures thereof included in various types of paper, paperboard, corrugated board, paper for packaging, other specialty papers, containers, molded pulp or other uses, cardboards, textiles and both woven and nonwoven material including but not limited to airlaid, drylaid, spunbond, spunlace, wetlace, meltblown and wetlaid nonwovens. id="p-15"

[0015] An oil or grease barrier in the context of the present invention has the meaning of repellency or antiwicking properties of a material towrads oil, greas, fat or other lipophilic agents or organic solvents, such as commonly used with KIT tests. Many such tests are well known to the skilled persons for example in applied paper technology and a non-limiting example is TAPPI T559 for grease resistance. id="p-16"

[0016] " " ' ln one aspect of the invention, the PEC of at least one composition includes a cationic biopolymer selected from cationic starch (CS) and/or chitosan and an anionic biopolymer selected from at least one of lâgniii aikaii, lâgncsuifonic acid, or a poiysaccharide, especially sodium carboxymethyi celiuiose (GMC), aiginic acid, pectiiw, carrageanan, gun: arabic, hernicaiiuiose, xanthan gurri, and nanocrystaiiiiwe ceiiulose (NCC), vifherein algšnic acid and iignosuifcnic acid preferably are present as their sodium satts. id="p-17"

[0017] ln one aspect of the invention, the material comprises a barrier comprising two layers formed from two compositions comprising a polyelectrolyte complex (PEC) of CS and CMC. The two compositions can comprise 0.1 to 20% (w/w) of CMC, and 0.1 to 20% of CS, preferably 0.5 to 10% (w/w) of CMC, and 0.5 to 20% of CS. id="p-18"

[0018] ln one aspect of the invention, at least one composition of the multi-layer barrier, has a defined pH and comprises a pH-adjuster selected from an acid, a buffering system and a base. According to this aspect the acid is one or more of an organic or inorganic acid. The organic acid is selected from one or more of acetic acid, acetylsalicylic acid, adipic acid, ascorbic acid, aspartic acid, benzenesulfonic acid, camphorsulfonic acid, citric acid, dihydroxy fumaric acid, esylic acid formic acid, glycolic acid, glutamic acid glyoxylic acid, hydrochloric acid, lactic acid, malic acid, malonic acid, maleic acid, mandelic acid, mesylic acid, oxalic acid, para-toluenesulfonic acid, pentanoic acid, phtalic acid, propionic acid, pyruvic acid, salicylic acid, sulfuric acid, tartaric acid, triflic acid, any amino acids, levulinic acid and succinic acid. The inorganic acid, for example, is a mineral acid selected from any of hydrogen halides: hydrochloric acid (HCI), hydrobromic acid (HBr), hydroiodic acid (HI) or the halogen oxoacids: hypochloric acid, chloric acid, perchloric acid, periodic acid and corresponding compounds for bromine and iodine, or from any of sulfuric acid (H2SO4), sulphamic acid, fluorosulfuric acid, nitric acid (HNO3), phosphoric acid (H3PO4), fluoroantimonic acid, fluoroboric acid, hexafluorophosphoric acid, chromic acid (H2CrO4) or boric acid (H3BO3). Preferably, the acid is present in the layer forming compositions in an amount of 0.01 to 30 % (vvíw), preferably the acid is selected from citric acid, lactic acid, oxalic acid and tartaric acid, more preferably the acid is 5 to 15% (w/w) of citric acid and/or lactic acid. The acid preferably results in pH of 2 to id="p-19"

[0019] The pH-adjuster of the previous aspect of the invention can be a buffering system so at least one composition comprises 0.01 to išüfš/fi (wiw) of an acid and a base pair, preferably a corresponding acid and base pair admitting a pH between 2 and 9, more preferably 1 to 15% (w/w) of said and a base pair. ln one embodiment, the composition comprises 1 to 10% (w/w) citric acid and 1 to 10% (w/w) tribasic citrate, preferably in equal amounts. id="p-20"

[0020] The pH-adjuster of the previous aspect of the invention can alternatively be a base, preferably the base is sodium hydrogen carbonate (NaHCOß), preferably providing a pH of 8 to »wu-»fl m ___» _» s ,.\=.» išßksi. usšl; x à: two compositions comprise PECs with the same relative amounts of CS and CMC; ln one aspect of the invention, the i.e. CS and CMC is present in the two compositions at the same %(wt). least one of the compositions of the multi-layer barrier, comprises a plasticizer, ln one aspect of the invention, at preferably the plasticizer is a polyol type plasticizer, more preferably the plasticizer is glycerol and/or sorbitol present in amount of 1 to 20% (w/w). id="p-23"

[0023] least one of the compositions of the multi-layer barrier, comprises an additive ln one aspect of the invention, at selected from ammonium zirconium carbonate; preservatives; defoamers; foammg agents, wetting agents; coalescerft agents; catalysts; surfactants; emuisifiers; cross-iinkers; vxfet strength additives such as epichiorohydriaw, rheoiogy modifâers; filters; :wonionic polymers; dyes and pigments. id="p-24"

[0024] material has a barrier from at least two applied layers having a KIT value of 5 or ln one aspect of the invention, the more, as measured according to T 999 pm-96 and COBB60 value of 50 or less, as measured according to ISO 536:191 (E). id="p-25"

[0025] material has a barrier wherein a first layer is made from a composition with a first ln one aspect of the invention, the pH value and a second layer is made from a composition having a second pH value, preferably the second layer is made from a composition having a lower pH value than the composition providing the first layer. ln one embodiment, the composition for the first layer comprises a buffering system according to what is outlined above, and the composition for the second layer comprises an acid according to what is outlined above. ln another specific embodiment, the first layer is made from a composition having a pH value of 3 to 6, comprising 5 to 20 % (w/w) of CS, 1 to 5 % (w/w) of CMC and a buffering system, comprising an acid and base pair selected from citric acid and a corresponding carboxylate of citric acid; and lactic acid and a corresponding carboxylate of lactic acid and the second layer is made from a composition having a pH value of 2 to 3, comprising 5 to 20 % (w/w) of CS, 1 to 5 % (w/w) of CMC and an acid selected from citric acid and lactic acid. The first and second layer are for example made from two compositions having the same relative amount in (w/w) of CS and CMC. ln one example of this embodiment, the first layer forming composition comprises 5 to % (w/w) of citric acid and tribasic citrate a second layer forming composition comprises 5 to 15% (w/w) of citric acid. Preferably, according to this embodiment, the first layer is the inner layer of the barrier and said second layer is outer layer of the barrier. id="p-26"

[0026] ln one aspect of the invention, the PEC of at least one composition has charge ratio that is :it The charge ratio represents the overati charge of the PEC formed front a cationic and an anionic biopoiymer, and is further defined in the exernpiifyirtg part of titis specification. id="p-27"

[0027] in other aspects of the invention, the PEC of at least one composition has charge ratio that is about f or above t. The skiiieo person can seiect the reiationship between cationic and ionic bioooiyrriers to obtain a ciose to netitrai net charge or anionic charge of the Ftšíï. For exarnpie the concentration of the anionic biopoiymer GMC can be increased in reiation to the cationic bioooiymer, as exernpiifieo by CS. tt wotiid atso be feasibie to seieot different brands of cationic hiopoiyrner trvith different charge densities in order to controi the charge ratio of the restitting PECs. The toiiowing detaiiecl and exempiifying part of the invention gives further gtiidance to the sitiiied person to controi charge dehsities of the inventive PEC compositions. id="p-28"

[0028] ln one aspect of the invention, the material has a barrier comprising at least one layer formed from at least one composition comprising a polyelectrolyte complex (PEC) of a cationic biopolymer and an anionic biopolymer and at least one layer comprising an amino-functional siloxane, or a layer comprising a hydrophobic agent, such as a Wax. Suitable compositions for forming layers comprising an amino-functional siloxane are the emulsified compositions disclosed in WO2018/048342 (hereby incorporated as a reference) to which conventional layer forming additives optionally can be added. Suitable compositions, for a layer comprising a hydrophobic material can be found in WO2018/038670 (hereby incorporated as a reference). Such compositions comprise PECs from cationic and anionic biopolymers with a charge ratio that is S1 and one more fatty compounds selected from oils, waxes and other lipid or hydrophobic agents. ln one embodiment of this aspect, the material comprises a barrier with two layers as outlined anywhere above and an additional layer comprising the now described amino-functional siioxane, or the layer comprising a hydrophobic agent id="p-29"

[0029] According to another aspect, the present invention relates to an aqueous polyelectrolyte_¿;;¿;;¿:¿j] (PEC) composition for application to a fibre based material for the use of obtaining a barrier coating resistant to oil and water, wherein the composition comprises: (a) 0.1 to 20% (vxf/xv) of šíllvïíljg and 0.1 to 20913 of _________________ ÅCSQ; preferably 0.5 to 10% (wlw) of CMC, and 0.5 to 20% of CIS, providing Pššíls vxfith a charge ratio of S 1; (b) 1 to 20% (w/w) of a plasticizer, preferably sorbitol; and (c) 1 to 15% (w/w) of a pH adjusting agent selected from an acid, buffering system and a base. id="p-30"

[0030] ln one embodiment, the composition comprises 5 to 20 % (w/w) of CS, 1 to 5% (w/w) of CMC, and 1 to 15% (w/w) of a buffering system consisting of an acid and base pair, preferably a corresponding acid and base pair derived from an organic acid, more preferably the buffering system is selected from citric acid/ corresponding carboxylate of citric acid and lactic acid/corresponding carboxylate of lactic acid. Preferably the composition has a pH of 3 to 6. Also preferably, the composition comprises equal amounts (w/w) of citric acid and tribasic citrate. id="p-31"

[0031] ln another embodiment, the composition comprises 5 to 20% (w/w) of CS, 1 to 5% (w/w) of CMC, and an organic or inorganic acid providing the composition with a pH of 1 to 3, preferably the acid is present in an amount of 0.01 to 301% (vv/w), more preferably the acid is selected front citric acid, lactic acid, oxalic acid and tartaric acid, more preferably the acid is 5 to 15% (w/w) of citric acid and/or lactic acid. id="p-32"

[0032] ln yet another embodiment, the composition comprises 5 to 20% (w/w) of CS, 1 to 5% (w/w) of CMC, and a base providing the composition with pH of 8 to 9, preferably the base is sodium hydrogen carbonate (NaHCOs). id="p-33"

[0033] The so embodied compositions can further comprise an additive selected from ammonium zirconium carbonate; preservatives; defoamers; foaming agents, tvetting agents; ooaieecent agents; oataiysts; surfaotants; ernoteifiers; prosa iinkere; rheoiogy rnodifiers; fiiiere; nonionio poiyinere; dyee and pigrnente. id="p-34"

[0034] Yet another aepect of the invention reietee to a kit with at least two compositions comprising: (a) 0.1 to EtP/ß (wivv) of GMC and 0.1 to 20% of CS, preferabiy 0.5 to 10%; (vv/tv) of CMC, and 5 to 2096 of CS, providing Ptštïe with a charge ratio of e t; (b) 1 to 20% (w/w) of a plasticizer, preferably sorbitol; and (c) 1 to 15% (w/w) of a pH adjusting agent selected from an acid, buffering system and a base. The kit is useful for forming barriers on a fiber based material and obtaining a barrier coating resistant to oil and water, said comprising a first compartment comprising a first composition with a buffering system and a second compartment with a second composition comprising an acid with a pH, lower than the first composition. The first composition can comprise 5 to 20 % (w/w) of CS, 1 to 5% (w/w) of CMC, and 1 to 15% (w/w) of a buffering system consisting of an acid and base pair, preferably a corresponding acid and base pair derived from an organic acid, more preferably the buffering system is selected from citric acid and a corresponding carboxylate of citric acid; and lactic acid and a corresponding carboxylate of lactic acid, and even more preferably the composition comprises equal amounts (w/w) of citric acid and tribasic citrate and has a pH of 3 to 6.The second composition can comprise 5 to 20% (w/w) of CS, 1 to 5% (w/w) of CMC, and an organic or inorganic acid providing the composition with a pH of 1 to 3, preferably the acid is present in an amount of0.01 to 30% (vvivv), preferabiy the acid is seieeted from citric acid, lactic acid, oxalic acid and tartaric acid, more preferably the acid is 5 to 15% (w/w) of citric acid and/or lactic acid. id="p-35"

[0035] The eo described kit vvith at ieast two compositions according to the invention is generaiiy aaeemhied in order to keep the oornpoeitions eeparated throughout shipping and storage and support convenient induetriai appiioation of the compositions in order to manufacture the invented rnaterieie with improved barriers. For this purpose, the compositions are stored eeparatety in different cornpartrnente of the kit which oan oe conventionai or euitabie separate oontainere avaiiaizie to a ekiiied peraon. The kit may aiso ooinprise a tisens inanuai in order to support application or htahutacturlhg methods aa outlitted ih the following section of the descriotiori. id="p-36"

[0036] ttottiei~ett ln still yet another aspect, the ihvention relates to a method of manufacturing the material according to any aspect or embodiment previously disclosed, comprising the steps of applying a first layer to the material with a composition comprising a polyelectrolyte complex (PEC) of a cationic biopolymer and an anionic biopolymer; optionally drying the material at a temperature between 15 and 900°C until essentially dry; followed by applying a second layer to the first layer with a second composition or the same composition again; and optionally curing the material. ln one embodiment curing is performed at 20 "C to 200 °C, more preferably at 50 °C to 200 "Q most preferably at åt) °t3 to 180 "<[0037] applying the first ancl seooho composition with at least one of the "lollowihg process stvQ :veätoiitšixit The rhethoo can be performed by 'šß 2: x technologies; spraylrig, roll coating; foolard coating; clip coating; screen coating; padding, impregnation, or tising a size press; a direct ooatihg method including knife coating, blade coating, wire wound bar coating, round bar coating and crushed foam coating; and an indirect coating methods including mayer rod coating, direct roll coating, kiss coating, gravure coating and reverse roll coating; preferably the application is performed with roll coating or foulard coating. id="p-38"

[0038] ln one embodiment of the invention, the method is performed in which the second composition applied is the same as the first composition. id="p-39"

[0039] rit; ln another embodiment of the invention, the first composition has a different pH than the second composition. Preferably, the first composition has a higher pH than the second composition. Also preferably, the first composition comprises 5 to 20 % (w/w) of CS, 1 to 5% (w/w) of CMC, and 1 to 15% (w/w) ofa buffering system consisting of an acid and base pair, preferably a corresponding acid and base pair derived from an organic acid, more preferably the buffering system is selected from citric acid and acorresponding carboxylate of citric acid; and |actic acid and a corresponding carboxylate of |actic acid, and even more preferably the composition comprises equal amounts (w/w) of citric acid and tribasic citrate and has a pH of 3 to 6. Also preferably, the second composition comprises 5 to 20% (w/w) of CS, 1 to 5% (w/w) of CMC, and an organic or inorganic acid providing the composition with a pH of1 to 3, preferably the acid is present in an amount of 0.01 to 30% (vv/vxf), preferably the acid is selected frorn citric acid, |actic acid, oxalic acid and tartaric acid, more preferably the acid is 5 to 15% (w/w) of citric acid and/or |actic acid.

Description of embodiments id="p-40"

[0040] Methods, equipment, chemicals and recipes Equipment used in the experiments: o The pH was measured using pHenomenal pH1000H from VWR with Hamilton Polilyte Lab Temp BNC electrode (calibrated with buffers pH 4, 7 and 10). o Particle charge was measured using Mütek PCD 02 device. o Stirring of formu|ations and pulp suspensions were done with overhead stirrer from IKA (either Eurostar digital IKA-Werke or IKA RW28 basic) together with a propeller shaft. o Homogenization of formu|ations was done using IKA T25 digital Ultra- Turrax. o Coating of materials was performed with a bench coater using a steel rod (called "coater") or Wichelhaus Wl-MU 505 A horizontal padder (called "padder"). o Weighing was done using XT 220A Precisa swissmade balance.

Methods: Method 1 - Solid content (SC)5 grams of powder or 10 grams of formulation was put in an aluminium cup and placed in oven at 105 °C over night. The solid content was then calculated using eq (4).

SC= (W2-W0)/W1 (4) where Wo = weight of the cup, W1 = Weight of the original sample and W2 = Weight of the cup and the final sample.

Method 2 - Charge density and charge ratio Charge density was measured using the Mütek PCD 02 device. Charge (symbol: q, unit: meqv) was calculated using eq (1). q ímeqVj: Ccounterion ' Vcounterion ' where the counter ion is one of sodium polyethylenesulphate (PES-Na, anionic) or poly-diallyl-dimethyl-ammonium-chloride (poly-dadmac, cationic), depending on the charge of the colloid. lf the charge at different concentrations are plotted against mass of the current colloid, the charge density (unit: meqv/g) is the slope of the linear curve. The mass of the colloid can be calculated using eq (2). g collolid m[g colloid] = wt% colloid 1 -g [g solution fo 10 ml] - 0,01 (2) g solution All charge densities are calculated on totally dry matter. When the charge densities are known for one polycation (eg. cationic starch) and one polyanion (eg. carboxymethyl cellulose), the charge ratio is calculated between the polyelectrolytes so that the overall charge of the complex becomes positive (i.e. charge ratio <1), see eq (3). [part of complex - charge density]polyanion Ch ' = arge ram) [part of complex - charge density]po1ycation Method 3 - Preparation of formulations Cationic starch was dissolved in water using a homogenizer at 60-70 °C in the presence of a biocide or used as pre-cooked starch concentrate. CMC was added to the dissolved cationic starch and dissolved using homogenization. lf additives were used, they were added and mixed in in the last step.

Method 4 - Coating of paper by rollCompositions were added to sheets of the material manually using a cylindrical steel rod. The treated papers were dried in an oven at 150 °C for 2-3 min.

Method 5 - KIT test/T 599 pm-Grease resistance test for paper and paperboard was measured according to T 599 pm-96, where the ranking is between 1 (bad barrier) and 12 (best possible barrier). Method 6 - COBB method/ ISO 536:191 (E) Determination of water absorption during 60 seconds (COBBGO) or 1800 seconds (COBB1800) was measured according to ISO 536:191 (E) Method 7 - lmpregnation of paper using padder Formulation was poured between the rolls in the padder and the pressure was set to 0.1 MPa and speed to 11.6 rpm. The treated paper was dried at 150 °C for 2-3 min. Method 8 - Spray test Determination of resistance to surface wetting (spray test) of fabrics: European Standard EN 24 920 (ISO 4920:1981). Principle: A specified amount of water is sprayed on a textile specimen mounted on a ring. The specimen is disposed at an angle of 45° in respect to the nozzle. The centre of the standardized nozzle is disposed at a given distance above the center of the specimen. A given amount of water is filled in a reservoir disposed above the nozzle and in communication with it. The spray rating is determined visually and/or photographically. The stepwise spray rating scale of ISO 1-5 corresponds to 50-100% of the specimen having withstood wetting.

Chemicals, materials and compositions: Chemicals used in the experiments are listed in table 1 and Table 1. Used polymersChemical Trade name Solid content Charge density Supplier or according to according to distributor Method 1 Method 2 Na FinnFix 5 87 % 3.78 CP Kelco Ca rboxymethyl cellulose (CI\/IC) Cationic starch Emfloc KCG 750 22 % 2.57 Emsland (CS) Cationic starch Emfloc ECG 750 22 % 2.84 Emsland (CS) Cationic starch Solcore 134 P 85 % 1.78 Solam (CS) Cationic starch Solbond PC 170 85 % 1.68 Solam (CS) MD Cationic starch Solbond PC 170 87% 1.65 Solam (CS) MP Cationic starch Hmat 1574A 86 % 1.08 Roquette (CS) Cationic sta rch Vector SCA 18 % 1.82 Roquette (CS)Table 2. Used chemicals Chemical Trade name Supplier Citric acid monohydrate - Univar Sodium tribasic citrate, - Univar dihydrate Lactic acid (80%) Galactic Food 80 Galactic S.A Sodium hydrogen carbonate Fisher Chemicals Potassium carbonate anhydrous Potassium carbonate anhydrous, reagent grade Fisher Chemicals Potassium hydroxide (46%) Kalilut 46% Evonic industries /Brenntag Nordic Sorbitol (70%) Plastilys (70%) Roquette Biobased binder OC-BiobinderOrganoClick AB isocyanates Silicone emulsion OrganoTex 310 OrganoClick AB Silicone emulsion OrganoTex 303 OrganoClick AB Emulsion of blocked Phobol XAN Huntsmann Papers and paper boards used in the experiments are listed in table 3 and Table 3. Paper types Unit Paper type 1 Paper type 2 Molded pulp Grammage g/m2 40 55 400 Thickness um 55 72Table 4. Paper board types Unit Paper board type 1 Paper board typeGrammage g/m2 330Compositions used in the experiments are listed in Table 5. Percent weight of the biopolymers in the compositions of Table 5 is calculated by considering their solid content in Table 1. lt should also be noted in Table 5 whenever CS and CMC were used alone as references, the recipes were based on 10-15 wt% biopolymers dissolved in tap water with a small amount of biocide.

Table 5. Compositions used in the examplesE 'U z a, '-t 'ë -ä å s å fä ä s 2 s ås S f. 2 5 g it å s š s .g t, g s 3 ß x 2 g ., a ä g 'ä 0 .E c F ._ o ° 2 N E >- 'å TE -o w n. u. o 'ä o o 2 o 0 : E 3 o -- UI g g 2 <4 'ß ä 'ëHF æ ß a -å E g o iI <3 ':E g Lu L" <3 5 <3 E fl E < f: o 1 2.63 9.77 87.4 0.2 100 0.62 2 2.63 9.77 87.4 0.2 100 0.94 3 1.86 10.54 20 67.4 0.2 100 0.62 4 1.86 47.43 20 30.51 0.2 100 0.45 5 3.21 51 20 25.7 0.09 100 0.73 6 4.2 39.7 56.01 0.09 100 0.64 7 5.8 36.9 57.21 0.09 100 0.95 8 3 11.6 85.31 0.09 100 0.55 9 2.7 56 41.21 0.09 100 0.56 10 3.8 49.7 46.49 0.01 100 0.88 11 5.4 35.5 8.9 50.1 0.09 100 1.76 12 3.21 51 5 5 14.29 21.41 0.09 100 0.73 13 3.21 51 10 14.29 21.41 0.09 100 0.73 14 3.8 40.9 55.3 0.09 100 0.62 15 4.5 38.1 57.4 0.09 100 0.EXAMPLES OF THE INVENTION Example 1. Comparative barrier performance test of only biopolymers compared to PEC ln order to elucidate if cationic starch and carboxy methyl cellulose respectively give rise to barrier properties and how these perform in contrast to when they are combined to a PEC, the following test was performed. Paper type 2 was coated according to method 4. Two layers were applied and the results are shown in tableTable 6. Comparison of PEC compositions 6 and 8 with their respective constituents KIT no Dry uptake layer 1 KIT no Dry uptake layer 2 layer 1 g/m2 layer 2 g/m2 CMC* 4 2,7 8 9,8 CS Solcore 134P* 1 3,7 5 12,8 Composition 8 1 7,2 11 14,2 CS Emfloc ECG 750* 1 3,8 1 11,2 Composition 6 1 4,3 11 9,*Compositions prepared as water solutions with the respective biopolymer in 10-13 wt%, 0,09 wt% Acticide AB6 and topped up with tap water.

Example 2. Importance of number of layers Paper type 2 was coated with composition 8 according to method 4 with either one layer and high add-on, or two layers with either 12,5 g/m2 or 14,2 g/m2, see table Table 7. KIT values measured on papers treated with different add-on applied in one or two layers Recipe Add-on (g/m2) Number of layers KIT no 12,5 2Composition 8 14,2 2 11 20,0 1The results highlight not only that the performance is dependent on the add-on but also that addition of two layers with sufficient add-on is highly beneficial for achieving high grease resistance represented by the KIT numbers as compared to onelayen Example 3. Application of PEC compositions with different charges Since a PEC can have different charges, it was decided to evaluate what effect these have on the grease resistance, see table 8. Two layers of the respective compositions were applied to paper type 2 using method 4. KIT-values were thereafter recorded using method Table 8. PEC compositions with different charges Recipe Number of layers Charge of PEC Dry uptake (g/m2) KIT no Composition 9 2 Cationic 13,7Composition 10 2 Neutral (close to 10,6 11 neutra|)/anionic Composition 6 2 Cationic 9,8 11 Composition 7 2 Neutral/anionic 11,9 9 Composition 14 2 Cationic 12,2 7 Composition 15 2 Neutral/anionic 15,9The results show that high grease barriers can be achieved with PEC compositions of different charges.

Example 4. Combination of different PEC composition layers Some compositions containing cationic starch create a sticky/tacky surface on the treated material, sometimes this is wanted sometimes not. ln this example, it is demonstrated how one can choose different compositions on the first and second layer to reduce stickiness, and improve KIT and/or COBB values. Application method 4 was used on paper type 2. Results are seen in table 9. A commercial binder called OC-Biobinder 5401 with more hydrophobic character was chosen to be combined with composition 1 of the invention.

Table 9. KIT, COBB and observations of the surface stickiness after application of barrier materials Paper type 2 KIT no COBB60 Observations Composition 1 5 55 * Very sticky 5401 1 80 Not sticky Layer 1: Composition 1, Layer 2: 5401 11 77 Not sticky Layer 1: 5401, Layer 2: Composition 1 5 39 Very sticky Paper type 1 KIT no COBB60 Observations Composition 1 9 33 * Very sticky 5401 0 80 Not sticky Layer 1: Composition 1, Layer 2: 5401 11 53 Not sticky Layer 1: 5401, Layer 2: Composition 1 11 37 Very sticky * sheet is very sticky and film is swelled in contact with water which affects the result It can be concluded that the order of application has an impact on the stickiness/tackiness, COBB and KIT values of the treated material. One can choose the order of addition depending on the wanted material Characteristics.

Example 5. Effect of adding a plasticizer on KIT and COBB valuesCarbohydrate based polymers are known to be stiff in their structure and hence the hand feel and the appearance of the treated material is expected to be stiff. In order to improve the folding properties of the treated material, reduce stiffness, reduce wrinkles of the dried paper and increase softness of the barrier coating, a common bio-based plasticizer was used and the amount optimized, see table Paper type 2 was coated with the given compositions in table 10 using method Table 10. KIT and COBB values after addition of sorbitol to PEC compositions * Amount sorbitol added to original PEC formulation (wt%) Composition Sorbitol Add KIT no COBB60 Layers (wt%)* on g/mComposition 6 0 9,2 11 39 2 Composition 6 +10 10 22,8 12 Measured 2 wt% sorbitol Directly:Measured after 24h:6 Layer 1: Composition 7 10 14,6 12 I\/Ieasured 2 Layer 2: Composition 6 directly: 39 +10 wt% sorbitol 72 h:Besides having a softening effect on the barrier coating it was seen that a certain amount of sorbitol has a positive influence on the KIT and COBB values of the treated material.

Example 6. Effect of different pH on the barrier properties A test was performed using pH adjusters as additives (acids and bases) to see if stickiness could be controlled while still maintaining KIT barrier properties. Paper grade 2 was coated using method 4, with 2 layers, see table Table 11. KIT and COBB values after pH adjustments of PEC compositions Recipe pH KIT nCOBBObservations Composition5,38,Sticky Composition 6+ 2 wt-% citric acid 3 11 46,5 Much less monohydrate sticky Composition 6+ NaHCO3 8,5 10 * More sticky Compos|t|on 6+ KOH (pH adjusted w|th a 46 8,5 10 * More Sticky wt% solution of KOH to pH 8,5) * COBBGO not possible to measure due to stickiness. lt can be seen that the papers treated with a formulation which has been adjusted to lower pH compared to the parent composition were much less sticky in relation to compositions that have been adjusted to higher pH as compared to the parent composition pH. Stickiness is a feature that in some cases is important for example in heat sealing processes.

Another observation that was made when adding citric acid monohydrate to composition 6 was that the dilutability became much better in the meaning that the PEC Composition did not form big precipitates when water was added to the formulation.

Example 7. Plasticized and pH adjusted compositions on different cellulose based materials ln a further example, combinations between plasticizer and pH adjustment additives were investigated. Compositions 12 and 13 were evaluated on paper type 2, molded pulp paper and paper board type 1 and 2. All materials were coated using method 4 with two layers of the compositions.

Table 12. Barrier properties on several materials for pH adjusted and plasticized PEC compositions.

Material Layer 1 Layer 2 KIT no COBBGO Comment Paper type 2 Composition 12 Composition 13 12Molded pulp paper - - 0 244 ReferenceMolded Pulp paper CompositionCompositionMolded Pulp paper CompositionCompositionPaper board type96* Reference Paper board typeCompositionComposition102* Paper board typeCompositionComposition96* Paper board typeCompositionComposition103* Paper board type103* Reference Paper board typeCompositionComposition87* Paper board typeCompositionComposition75* Paper board typeCompositionComposition86* *COBB1800 was performed since the material was paperboard The combination of PEC with plasticizer and pH adjustment additive yield very promising results in both COBB and KIT values and hence a good water and grease barrier on the coated materials. lt is also clear that application of composition 12 yields a good grease barrier while composition 13 results in good water barrier and most importantly these coatings seem not to interfere with each other but work synergistically.

Example 8. Combination of PEC and non-PEC coatings on various materialsTo further extend the usage of the invention, textile material was coated. A white polyester fabric with a grammage of 150 g/m2 was coated according to method 4 with PEC compositions 1 and 2 respectively and subsequently further coated using method 7 using commercially available hydrofobizing products OC-aquasil Tex 310 or OC-aquasil Tex 303. Results are presented in the table Table 13. Polyester fabric coated with compositions 1st and 2nd layer 3rd layer Spray score KIT no Composition 1 and OrganoTex 310 -2- Proof 5-6 CompositionComposition 1 and Tex 303 + 10% XAN +3 Proof 7 Compositionlt can be concluded that the current invention is also capable of creating a good barrier for water and grease on textile which is of much lower density compared to for example paper.

Claims (9)

1. An aqueous polyelectrolyte complex (PEC) composition for application to a fibre based material for the use of obtaining a barrier coating resistant to oil and water, wherein the composition comprises: (a) 6.1 to 26% (wiw) of carboxymethyl celluloso (Cliflíl) and 0.1 to 2693 of oatlonic starch (CS), preferably 6.5 to 16913 (wlw) of CMC, and lt) to 26% of CS, providing PECs with a charge ratio of ä. 1; (b) 1 to 20% (w/w) of a plasticizer, preferably sorbitol; and (o) 1 to 15% (w/w) of a pH adjusting agent selected from an acid, buffering system and a base.

2. The composition according to claim 1, comprising 5 to 20 % (w/w) of CS, 1 to 5% (w/w) of CMC, and 1 to 15% (w/w) ofa buffering system consisting of an acid and base pair, preferably a corresponding acid and base pair derived from an organic acid, more preferably the buffering system is selected from citric acid and a corresponding carboxylate of citric acid; and lactic acid and a corresponding carboxylate of lactic acid.

3. The composition according to claim 2, comprising equal amounts (w/w) of citric acid and tribasic citrate.

4. The composition according to claim 2 or 3, having a pH of 3 to

5. The composition according to claim 1, comprising 5 to 20% (w/w) of CS, 1 to 5% (w/w) of CMC, and an organic or inorganic acid providing the composition with a pH of 1 to 3, preferably the acid is present in an amount of 0.61 to 30% fvviw), preferably the acid is selected from citric acid, lactic acid, oxalic acid and tartaric acid, more preferably the acid is 5 to 15% (w/w) of citric acid and/or lactic acid.

6. The composition according to claim 1, comprising 5 to 20% (w/w) of CS, 1 to 5% (w/w) of CMC, and a base providing the composition with pH of 8 to 9, preferably the base is sodium hydrogen carbonate (NaHCOs).

7. The composition according to any one of claims 1 to 6, comprising an additive selected from ammonium zirconium carbonate; preservatives; defoamers; foarning agents, vtfetting agents; coaiescent agents; catalysts; surfactants; emuisifiers; crossiinkers; rheoiogy modifiers; filters; nonionic poitfmers; dïfes and pšgrnents.

8. A kit with at least two compositions according to claim 1, for application to a fibre based material for the use of obtaining a barrier coating resistant to oil and water comprising a first compartment with a composition with a buffering system and a second compartment with a composition comprising an acid with a pH, lower than the first composition.

9. A kit according to claim 8, wherein the first composition is the composition according to any one of claims 2 to 4, and wherein the second composition is the composition according to claim 5.