FLUOROCARBON-FREE AND BIOBASED OIL AND WATER BARRIER MATERIALS COMPRISING POLYELECTROLYTE COMPLEXES

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.

Claims

1.-38. (canceled)

39. A fibre-based material with a barrier coating against oil and water, said barrier coating comprising at least two layers formed from at least one composition comprising a polyelectrolyte complex (PEC) of a cationic biopolymer and an anionic biopolymer and a pH-adjuster comprising a buffering system with an acid and a base, wherein the first layer is made from a composition with a first pH value and the second layer is made from a composition having a second pH value, and wherein 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.

40. The material according to claim 39, wherein the cationic biopolymer is selected from cationic starch (CS) and chitosan, and the anionic biopolymer is selected from at least one of lignin alkali, lignosulfonic acid, and a polysaccharide.

41. The material according to claim 40, wherein the polysaccharide comprises at least one of sodium carboxymethyl cellulose (CMC), alginic acid, pectin, carrageenan, gum arabic, hemicellulose, and nanocrystalline cellulose (NCC).

42. The material according to claim 40, wherein the two layers are formed from two compositions comprising a polyelectrolyte complex (PEC) of CS and CMC.

43. The method according to claim 42, wherein the two compositions comprise from 0.1 to 20% (w/w) of CMC and from 0.1 to 20% of CS.

44. The method according to claim 42, wherein the two compositions comprise from 0.5 to 10% (w/w) of CMC and from 0.5 to 20% of CS.

45. The material according to claim 42, wherein the two compositions comprises PECs with the same relative amounts of CS and CMC.

46. The material according to claim 39, wherein the buffering system provides 0.01 to 30% (w/w) of a corresponding acid and a base pair admitting a pH from 2 to 9 to the composition.

47. The material according to claim 39, wherein at least one of the layer-forming compositions comprises a plasticizer, wherein the plasticizer is a polyol type plasticizer.

48. The material according to claim 39, wherein the barrier has KIT value of 5 or more, as measured according to T 999 pm-96 and a COBB60 value of 50 or less, as measured according to ISO 536:191(E).

49. The material according claim 39, wherein said first layer is the inner layer of the barrier and said second layer is the outer layer of the barrier.

50. An aqueous polyelectrolyte (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) from 0.1 to 20% (w/w) of CMC and from 0.1 to 20% of CS, providing PECs with a charge ratio of ≤1; (b) from 1 to 20% (w/w) of a plasticizer; and (c) from 1 to 15% (w/w) of a pH adjusting agent selected from an acid, a buffering system and a base.

51. The composition according to claim 50, comprising from 5 to 20% (w/w) of CS, from 1 to 5% (w/w) of CMC, and from 1 to 15% (w/w) of a buffering system consisting of an acid and base pair, corresponding to an acid and base pair derived from an organic acid.

52. The composition according to claim 50, comprising from 5 to 20% (w/w) of CS, from 1 to 5% (w/w) of CMC, and a base providing the composition with pH of 8 to 9.

53. A method of manufacturing the material according to claim 39, comprising the steps of: applying a first layer to the material with a first composition comprising a polyelectrolyte complex (PEC) of a cationic biopolymer and an anionic biopolymer; optionally drying the material at a temperature between 15 and 90° C.; applying a second layer to the first layer with a second composition; and curing the material at a temperature between 15 and 90° C.

54. The method according to claim 53, wherein curing is performed at 20° C. to 200° C.

55. The method according to claim 53, wherein the first composition has a different pH than the second composition.

56. The method according to claim 55, wherein the first composition has a higher pH than the second composition.

Description

DESCRIPTION OF EMBODIMENTS

Methods, Equipment, Chemicals and Recipes

Equipment Used in the Experiments:

[0044] The pH was measured using pHenomenal pH1000H from VWR with Hamilton Polilyte Lab Temp BNC electrode (calibrated with buffers pH 4, 7 and 10). [0045] Particle charge was measured using Mütek PCD 02 device. [0046] Stirring of formulations and pulp suspensions were done with overhead stirrer from IKA (either Eurostar digital IKA-Werke or IKA RW28 basic) together with a propeller shaft. [0047] Homogenization of formulations was done using IKA T25 digital Ultra-Turrax. [0048] Coating of materials was performed with a bench coater using a steel rod (called “coater”) or Wichelhaus WI-MU 505 A horizontal padder (called “padder”). [0049] Weighing was done using XT 220A Precisa swissmade balance.

METHODS

Method 1—Solid Content (SC)

[0050] 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=(W.sub.2−W.sub.0)/W.sub.1  (4)

[0051] where W.sub.0=weight of the cup,

[0052] W.sub.1=Weight of the original sample and

[0053] W.sub.2=Weight of the cup and the final sample.

Method 2—Charge Density and Charge Ratio

[0054] Charge density was measured using the Mütek PCD 02 device. Charge (symbol: q, unit: meqv) was calculated using eq (1).

q[meqv]=C.sub.counter ion[eqv/l].Math.V.sub.counter ion[l].Math.1000  (1)

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. If 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).

[00001]$\begin{array}{cc}m\left[g\mathrm{colloid}\right]=\mathrm{wt}\%\mathrm{colloid}\left[\frac{g\mathrm{colloid}}{g\mathrm{solution}}\right].Math.g\left[g\mathrm{solution}fo10\mathrm{ml}\right].Math.0.01& \left(2\right)\end{array}$

[0055] 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).

[00002]$\begin{array}{cc}\mathrm{Charge}\mathrm{ratio}=\frac{\left[\mathrm{part}\mathrm{of}\mathrm{complex}.Math.\mathrm{charge}\mathrm{density}\right]\mathrm{polyanion}}{\left[\mathrm{part}\mathrm{of}\mathrm{complex}.Math.\mathrm{charge}\mathrm{density}\right]\mathrm{polycation}}& \left(3\right)\end{array}$

Method 3—Preparation of Formulations

[0056] 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. If additives were used, they were added and mixed in in the last step.

Method 4—Coating of Paper by Roll

[0057] Compositions 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-96

[0058] 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)

[0059] Determination of water absorption during 60 seconds (COBB.sub.60) or 1800 seconds (COBB.sub.1800) was measured according to ISO 536:191 (E)

Method 7—Impregnation of Paper Using Padder

[0060] 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

[0061] 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.

[0062] Chemicals, Materials and Compositions:

[0063] Chemicals used in the experiments are listed in table 1 and 2.

TABLE-US-00001 TABLE 1 Used polymers Solid Charge content density according to according to Supplier or Chemical Trade name Method 1 Method 2 distributor Na FinnFix 5 87% 3.78 CP Kelco Carboxymethyl cellulose (CMC) Cationic starch Emfloc 22% 2.57 Emsland (CS) KCG 750 Cationic starch Emfloc 22% 2.84 Emsland (CS) ECG 750 Cationic starch Solcore 85% 1.78 Solam (CS) 134 P Cationic starch Solbond 85% 1.68 Solam (CS) PC 170 MD Cationic starch Solbond 87% 1.65 Solam (CS) PC 170 MP Cationic starch Hi-Cat 86% 1.08 Roquette (CS) 1574A Cationic starch Vector SCA 18% 1.82 Roquette (CS) 2015

TABLE-US-00002 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 — Fisher Chemicals carbonate Potassium carbonate Potassium carbonate Fisher Chemicals anhydrous anhydrous, reagent grade Potassium hydroxide Kalilut 46% Evonic (46%) industries/Brenntag Nordic Sorbitol (70%) Plastilys (70%) Roquette Biobased binder OC-Biobinder 5401 OrganoClick AB Silicone emulsion OrganoTex 310 OrganoClick AB Silicone emulsion Orga noTex 303 OrganoClick AB Emulsion of blocked Phobol XAN Huntsmann isocyanates

[0064] Papers and paper boards used in the experiments are listed in table 3 and 4.

TABLE-US-00003 TABLE 3 Paper types Unit Paper type 1 Paper type 2 Molded pulp Grammage g/m2 40 55 400 Thickness μm 55 72 1500

TABLE-US-00004 TABLE 4 Paper board types Unit Paper board type 1 Paper board type 2 Grammage g/m2 330 260

[0065] Compositions 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. It 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-US-00005 TABLE 5 Compositions used in the examples Composition Solbond Hi-Cat Vector Emfloc Emfloc Solcore number # FinnFix 5 PC 170 MP 1574 A SCA 2015 ECG 750 KCG 750 134 P 1 2.63 9.77 2 2.63 9.77 3 1.86 10.54 4 1.86 47.43 5 3.21 51 6 4.2 39.7 7 5.8 36.9 8 3 11.6 9 2.7 56 10 3.8 49.7 11 5.4 35.5 12 3.21 51 13 3.21 51 14 3.8 40.9 15 4.5 38.1 Citric Sodium acid tri basic Composition mono citrate Tap Nipacide Acticide Charge number # hydrate di hydrate Plastilys water BSM AB6 Sum ratio 1 87.4 0.2 100 0.62 2 87.4 0.2 100 0.94 3 20 67.4 0.2 100 0.62 4 20 30.51 0.2 100 0.45 5 20 25.7 0.09 100 0.73 6 56.01 0.09 100 0.64 7 57.21 0.09 100 0.95 8 85.31 0.09 100 0.55 9 41.21 0.09 100 0.56 10 46.49 0.01 100 0.88 11 8.9 50.1 0.09 100 1.76 12 5 5 14.29 21.41 0.09 100 0.73 13 10 14.29 21.41 0.09 100 0.73 14 55.3 0.09 100 0.62 15 57.4 0.09 100 0.79

EXAMPLES OF THE INVENTION

Example 1. Comparative Barrier Performance Test of Only Biopolymers Compared to PEC

[0066] In 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 table 6.

TABLE-US-00006 TABLE 6 Comparison of PEC compositions 6 and 8 with their respective constituents KIT no Dry uptake KIT no Dry uptake layer 1 layer 1 g/m2 layer 2 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 1 3.8 1 11.2 750* Composition 6 1 4.3 11 9.2 *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

[0067] 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 7.

TABLE-US-00007 TABLE 7 KIT values measured on papers treated with different add-on applied in one or two layers Add-on Number of KIT Recipe (g/m2) layers no Composition 8 12.5 2 7 14.2 2 11 20.0 1 5

[0068] The 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 one layer.

Example 3. Application of PEC Compositions with Different Charges

[0069] 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 5.

TABLE-US-00008 TABLE 8 PEC compositions with different charges Number of Charge Dry uptake KIT Recipe layers of PEC (g/m2) no Composition 9 2 Cationic 13.7 7 Composition 10 2 Neutral (close to 10.6 11 neutral)/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 15.9 11

[0070] The results show that high grease barriers can be achieved with PEC compositions of different charges.

Example 4. Combination of Different PEC Composition Layers

[0071] Some compositions containing cationic starch create a sticky/tacky surface on the treated material, sometimes this is wanted sometimes not. In 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-US-00009 TABLE 9 KIT, COBB and observations of the surface stickiness after application of barrier materials KIT no COBB60 Observations Paper type 2 Composition 1 5 .sup. 55 * Very sticky 5401 1 80 Not sticky Layer 1: Composition 1, 11 77 Not sticky Layer 2: 5401 Layer 1: 5401, Layer 2: 5 39 Very sticky Composition 1 Paper type 1 Composition 1 9 .sup. 33 * Very sticky 5401 0 80 Not sticky Layer 1: Composition 1, 11 53 Not sticky Layer 2: 5401 Layer 1: 5401, Layer 2: 11 37 Very sticky Composition 1 * sheet is very sticky and film is swelled in contact with water which affects the result

[0072] 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 Values

[0073] Carbohydrate 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 10. Paper type 2 was coated with the given compositions in table 10 using method 4.

TABLE-US-00010 TABLE 10 KIT and COBB values after addition of sorbitol to PEC compositions Sorbitol Add on KIT Composition (wt %)* g/m2 no COBB60 Layers Composition 6 0 9.2 11 39 2 Composition 6 + 10 22.8 12 Measured Directly: 32 2 10 wt % sorbitol Measured after 24 h: 6 Layer 1: Composition 7 10 14.6 12 Measured directly: 39 2 Layer 2: Composition 6 + 72 h: 30 10 wt % sorbitol *Amount sorbitol added to original PEC formulation (wt %)

[0074] 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

[0075] 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 11.

TABLE-US-00011 TABLE 11 KIT and COBB values after pH adjustments of PEC compositions Recipe pH KIT no COBB.sub.60 Observations Composition 6 5.5 11 38.5 Sticky Composition 6 + 2 wt-% 3 11 46.5 Much less citric acid monohydrate sticky Composition 6 + 8.5 10 * More sticky NaHCO3 Composition 6 + KOH 8.5 10 * More sticky (pH adjusted with a 46 wt % solution of KOH to pH 8.5) * COBB.sub.60 not possible to measure due to stickiness.

[0076] It 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.

[0077] 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

[0078] In 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-US-00012 TABLE 12 Barrier properties on several materials for pH adjusted and plasticized PEC compositions. KIT Material Layer 1 Layer 2 no COBB.sub.60 Comment Paper Composition Composition 12 35  type 2 12 13 Molded 0 244  Reference pulp paper Molded Composition Composition 10 50  pulp 12 12 paper Molded Composition Composition 11 33  pulp 12 13 paper Paper — — 0 96* Reference board type 1 Paper Composition Composition 12 102*  board 12 12 type 1 Paper Composition Composition 12 96* board 12 13 type 1 Paper Composition Composition 12 103*  board 13 12 type 1 Paper — — 0 103*  Reference board type 2 Paper Composition Composition 12 87* board 12 12 type 2 Paper Composition Composition 12 75* board 12 13 type 2 Paper Composition Composition 12 86* board 13 12 type 2 *COBB.sub.1800 was performed since the material was paperboard

[0079] 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. It 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 Materials

[0080] To 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 13.

TABLE-US-00013 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 Composition 2 Composition 1 and Tex 303 + 10% XAN +3 Proof 7 Composition 2

[0081] It 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.