Water insoluble polyelectrolyte complexes

Abstract

The present invention discloses polyelectrolyte complexes (PECs), e.g. water insoluble PECs, obtained by reacting a negatively charged hemicellulose-lignin co-polymer with a cationic polymer. The negatively charged hemicellulose-lignin co-polymers is selected from lignin carbohydrate complexes (LCC) from pre-hydrolysis sulphite pulping, LCC from pre-hydrolysis kraft pulping, LCC from mechanical pulping and chemical / mechanical pulping (TMP and CTMP). The cationic polymer is selected from cationic polysaccharides and cationic starches. Methods for production of PECs, are also disclosed.

Description

[0001] Water insoluble polyelectrolyte complexes

[0002] Technical Field

[0003] The present invention generally relates to water insoluble polyelectrolyte complexes (PECs), in particular environmentally friendly such complexes with properties suitable for application as barrier materials and / or adhesives.

[0004] Background

[0005] The packaging industry is looking for bio-based alternatives for their barrier materials and adhesives. The oxygen, grease and water barriers in the packaging industry consists mainly of non-renewable materials. The need for more environmentally friendly barrier materials, (bio-based, renewable, recyclable and biodegradable) is evident especially together with paper boards that are used in the packaging sector. The main drawback with the bio-based materials is the rather low availability and often lower performance compared to oil-based polymers especially when it comes to water and oxygen barrier properties (compared to polyethylene, ethylene vinyl alcohol).

[0006] A polyelectrolyte complex (PEC) in water between two oppositely charged polymers can behave in many different ways depending on the charge of the individual polymers, type of an-ionic and cat-ionic polymer, molecular weights, ratio between the polymers, concentration, temperature and salt concentration. The driving force for the formation of PECs is the increase in entropy and the release of many smaller ions. Many PECs have been reported in the literature and also between different bio-based polymers.

[0007] One example where lignin (lignosulfonate) is used is described in the article “’Polyelectrolyte Complexes: Lignosulfonate and Chitosan” Biomacromolecules 2003, 4, 232-239. In this article PECs between chitosan and lignosulfonate were prepared and characterized.

[0008] US2013 / 289255 A1 is directed towards a method to increase the molecular weight of wood mannans and xylans comprising aromatic moieties. Therein is discloses examples of production of films, including a step consisting of the mixing of a mixture of polyethyleneimine and glycerol into water solutions of low and high molecular weight fractions of polymerized materials, originating from process waters of thermomechanical pulping. In the patent US10,342,228 B2 a polyelectrolyte complex between lignosulfonate and chitosan and a biocide is used for plant protection.

[0009] In WO2015 / 034357 A1 , a polyelectrolyte complex consisting of lignosulfonate is used in paint applications. A method for producing a paint composition is taught therein. The method comprises a step of mixing a solution of a polycation with a solution of a polyanion, whereby a precipitate is formed, followed by another step, in which the formed precipitate is crushed to form a suspension. One disadvantage of such this method is, for example, a need to crush the precipitate to yield the suspension, which brings about an extra operational step in comparison to the case when the suspension could be formed without crushing.

[0010] Disadvantages of the above-mentioned PECs include limited film forming ability and limited barrier properties. Lignosulfonate polymers doesn’t contain any polysaccharides to give suitable film and barrier properties of the formed PECs. The impurity and large molecular weight distribution of lignosulfonate is also and disadvantage.

[0011] It would be advantageous with a PEC for as use as a barrier material or adhesive that allows for avoiding at least some of the above mentioned disadvantages and associated problems.

[0012] Summary

[0013] It is an object of the invention, considering the disadvantages mentioned above, to provide an environmentally friendly PEC for use as an oxygen, grease and / or water barrier.

[0014] It is another object of the invention, considering the disadvantages mentioned above, to provide an environmentally friendly PEC for use as an adhesive.

[0015] It is yet another object of the invention, considering the disadvantages mentioned above, to provide an environmentally friendly PEC for use as a binder.

[0016] It is further yet another object of the invention, considering the disadvantages mentioned above, to provide a bio-based PEC in a form suitable for coating applications, for example in the form of an practically stable water dispersion for application. Accordingly, examples of the present invention preferably seek to mitigate, alleviate or eliminate one or more deficiencies, disadvantages or issues in the art, such as the above-identified, singly or in any combination by providing a PEC according to the appended patent claims.

[0017] According to a first aspect, there is provided a PEC comprising a negatively charged high molecular weight hemicellulose-lignin co-polymers (NHCL), e.g. belonging to the group described in US 2013 / 0289255A1 , and a cationic polymer (CP). The NHCL is selected from the group consisting of lignin carbohydrate complexes (LCC) from pre-hydrolysis sulphite pulping, LCC from pre-hydrolysis kraft pulping, LCC from mechanical pulping and chemical / mechanical pulping (TMP and CTMP). Tthe cationic polymer is having a degree of substitution in the range of 0.08 to 0.81 , such as 0.65-0.81 , and is selected from the group consisting of cationic polysaccharides and cationic starches.

[0018] According to a second aspect, there is provided use of a PEC of the first aspect as a barrier material, for example in a food packaging material to improve grease and oxygen barrier properties, or as an adhesive or as a binder, for example in a food packaging material.

[0019] According to a third aspect, there is provided a method for production of a PEC of the first aspect comprising the step of mixing a Woodmer®, e.g. a water soluble Woodmer® (lignin carbohydrate complex), at a concentration of at least 10 w%, with a cationic polymer, e.g. a water-soluble cationic polymer, with a concentration of at least 10 w%. The PEC thus obtained may typically be in a gel form or in the form of a stable PEC particle dispersion or suspension with low or at least acceptable viscosity and may thus be useful and allow for the practice and application as an adhesive and / or a binder. It may also be useful as a barrier in particular applications, as understood by the one skilled in the art.

[0020] It should be emphasized that the term “comprises / comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. Description

[0021] It was surprisingly found that negatively charged high molecular weight hemicellulose-lignin co-polymers belonging to the group described in US 2013 / 0289255A1 , herein referred to as ‘Woodmer®’, form PECs with desirable properties when allowed to react with various cationic polymers, as disclosed herein. Woodmer’s® very defined lignin-carbohydrate structures and highly negatively charge at all pH values (sulfonate groups and a charge density of 2,2 mmol / g substrate) seemingly allows for the formation of stable, strong and well defined PECs when combined with cationic polymers. Such PECs are thus suitable for barriers, adhesive and binder applications.

[0022] The Woodmer® polymer alone, especially produced from the sulphite pulping side streams, is not suitable as a barrier material. The polymer has limited film forming properties and tend to be brittle and weak. It was found that together with a cationic polymer, better properties were observed than using the polymer alone. A synergistic effect was achieved. The highly charged Woodmer® hemicellulose lignin co-polymers formed strong complexes with cationic polymers. These polyelectrolyte complexes were formed in water and could be used as a barrier material on paper boards creating good grease resistance, low oxygen permeability and low or no water solubility. Properties that are good for barrier materials in the packaging industry.

[0023] One interesting feature of the invention was that the laccase enzyme reaction also increased more negative charge of the hemicellulose-lignin copolymers. Lignin and hemicelluloses often has natural negative charge because of carboxylic acids or phenolic groups on the lignin. The type of pulping process will also affect the charge on the hemicellulose-lignin. The sulphite pulping process where sulfonic acid groups are introduced to the lignin creates highly charged water-soluble lignin. It was surprisingly found that the laccase reaction on a pre-hydrolysis side stream from a sulphite pulp mill also increased the charged of the resulting polymer together with an increase in molecular weight. This increase in negative charge was a contributing factor for the strong complexes with cationic polymers. A feature that could be utilised in the film barrier applications.

[0024] Several different Woodmer® polymers created from the laccase reaction of pulp and paper side streams were tried in this invention. Woodmer® polymers were produced from CTMP (chemical / mechanical pulp), TMP (mechanical pulping) and sulphite pulping (dissolving pulp). Several cat-ionic polymers were then examined to form a suitable polyelectrolyte complex with these negatively charged LCC polymers. Below is a list of different cat-ionic polymers and Woodmer® polymers produced from different pulp and paper mill processes. The goal was to find a 100% bio-based PEC and therefore a biobased cat-ionic polymer was preferable than a synthetic one.

[0025] Examples of cationic polymers: Chitosan (bio-based), Cat-ionic starch (bio-based), Polyethylene imine (synthetic), Vinyl amine (synthetic) and Allyl amine (synthetic).

[0026] Examples of an-ionic Woodmer® polymers: hemicellulose-lignin copolymers (Woodmer® CAS RN: 2769734-64-5) Woodmer® polymer produced from pre-hydrolysis sulphite cooking process of softwood (Dornsjo process), Woodmer® polymer produced from the TMP process (mechanical pulping process) and Woodmer® polymer produced from CTMP process (chem / mechanical pulping process), Woodmer® polymer produced from the pre-hydrolysis of the Kraft process.

[0027] A PEC between two water soluble polymers with opposite charge can behave very differently according to the above described factors. Below are a few examples how the PECs behaved between the Woodmer® polymer produced from the pre-hydrolysis sulphite cooking process (DH13 and DH14) and different cat-ionic starches. The goal was to find a stable PEC that could be stored over time. Ready for future coating applications. Gelling or precipitation is an example of a PEC not suitable for barriers or adhesives. Precipitaed PECs can have other applications. Below are a few examples how the PECs can behave.

[0028] • Stable transparent PEC with low viscosity

[0029] • Gelling and highly viscous transparent PEC

[0030] • Stable PEC particle dispersions with low viscosity

[0031] • Gelling of the particle dispersion

[0032] • Complete precipitation

[0033] The aim of this invention was to use the high amount of negative charge of the Woodmer® hemicellulose-lignin co-polymers formed by the laccase enzyme reaction as the basis for these PEC formulations. It was believed that a highly positive cat-ionic polymer could form a very strong polyelectrolyte complex with the Woodmer® LCC.

[0034] Characterisation of the PEC between Woodmer® polymers and cationic polymers

[0035] Most of the produced PECs in the below example descriptions were focused on cat-ionic starches and Woodmer® polymers produced from the Dornsjo pre-hydrolysis cocking liquor. The goal was to produce stable PECs that could be used for paper board coating applications and adhesive applications. The characterisation of the PECs was based on stability studies and water solubility observations. A successful PEC had to be homogenous with appropriate viscosity for paper board coatings. The non-water solubility properties also had to be fulfilled. This meant that the PEC precipitated if water was added or if the PEC was added to water. The dried films of the corresponding PECs had to be insoluble in water to prove a successful PEC.

[0036] Vector (Vector IC 42280-EXP-EX-LAB 4202) cat-ionic starch from Roquette (with high amount of charge). Nitrogen content of 3, 5-4,0, % and degree of substitution 0,65-0,81 produced very strong non-water soluble PECs with the Woodmer® polymer. These strong PECs could then be used for free standing film formation which neither of the starting polymers were suitable for. The films and dry coatings of these PECs showed good barrier properties against grease, water and oxygen. Another observation was that a high solid content was achieved with these PECs. A concentration of up to 50% was possible, which is beneficial for coating applications or adhesive applications were the amount of water that needs to be removed during drying can be an issue. Different plasticisers and other additives were added to the PECs to further improve and their corresponding free-standing films. Especially, sorbitol was useful to increase the flexibility of the films.

[0037] The stability of the PECs formed between the Woodmer® polymer and cat-ionic starches was an issue. If the wrong ratio between the two polymers were used, precipitation took place. If a stable PEC was stored over time, gelling often took place. These features made the coating applications impossible. The reason for the precipitation may be that a non-ideal ratio of the polymers were used, based on their relative charge or molecular weight. For each Woodmer® polymer and cat-ionic starch, the right ratio had to be determined. A high concentration of the produced PECs was also important. A high PEC concentration lowers the polymer interaction because of the very high salt concentration in the mixture. The salts disrupt the PECs. When the PECs are more diluted the salt concentration is lower and the polymer interaction increases.

[0038] Woodmer® polymer DH13 - Vector (cat-ionic starch) PEC

[0039] Below is a table describing the initial PECs made from Woodmer® polymer produced from the Dornsjo pre-hydrolysis stream (DH13) and Vector IC 42280-EXP-EX-LAB 4202, (41 ,7%), Roquette. For Woodmer® and Vector a solid content ratio of 45:55 was the optimum for stability issues.

[0040] The only workable PEC mixtures were the first (table 1 ), where an equal amount of the different polymers were used . Then going up in DH13 amount gelling and precipitation took place. Probably due to more neutral net charge. PEC formulation 5 with large excess DH13 worked but produced a bad film even with sorbitol. A PEC with higher Vector ratio was also possible to produce. The film from formulation 1 b had good mechanical properties and was slightly flexible (see figure 1 ).

[0041] Table 1. PEC and free-standing film formation based on Vector-DH13 PECs

[0042] Figure 1. Film produced from formulation lb

[0043] Example 2 - Woodmer® polymer and cat-ionic starch (Solcore 134 P from solam)

[0044] A PEC with an excess of cat-ionic starch Solcore 134P from Solam (degree of substitution of 0.134), compared to DH13 was possible to produce (formulation 3) or an excess of DH13 compared to the cat-ionic starch (formulation 5, table 2). Probably, a neutral net charge caused the gelling effect of the PEC complexes. The gelling was also affected by the concentration of the polymers in water. Formulation 3 was suitable for producing a free-standing film that were not soluble in water (figure 2).

[0045] Table 2. Solcore 134-DH13 PEC

[0046] Table 3. Solcore 134-DH13 PEC

[0047] Figure 2. To the left. Film made from Woodmer® DH13 dissolved in water. To the right. Film made from DH13-Solcore PEC, which was intact in water

[0048] Example 3 - Improving the stability of PECs using DH14 and Vector starch from Roguette

[0049] The right amount of Woodmer® polymer to the cationic starch was important to produce a stable PEC mixture and to avoid precipitation. The previously formed PECs between Woodmer® polymers and cationic starch often gelled during storage. Even though the PEC seemed stable initially with no precipitation and low viscosity, gelling often took place after a few hours or over-night. This could be a disadvantage for coating applications.

[0050] The solution to form stable PECs and removal of air bubbles was to ad small amounts of ethanol during the PEC formulation. The ethanol reduced the viscosity and increased the stability over time for the PECs. The drying time

[0051] could also be improved by the addition of ethanol. In the below examples a different batch of Woodmer® polymer was used, DH14 produced from the prehydrolysis stream from the Dornsjo mill.

[0052] Procedure

[0053] The perfect ratio between DH14 and Vector based on dry weight was about 45:55 and with a final concentration of about 30% (sorbitol not included).

[0054] Formulation 1

[0055] 10 mL of Vector (4,91 g) was mixed with 5 mL ethanol. 20 mL DH14 F (4,25 g) was added and the PEC was mixed before 2 g sorbitol was added. After the addition of sorbitol mixing was continued and then the PEC was ready for coating. The PEC was stable over time.

[0056] Formulation 2

[0057] 10 mL of Vector (4,91 g) was mixed with 10 mL ethanol. 20 mL DH14 F (4,25 g) was added and the PEC was mixed before 4 g sorbitol was added. After the addition of sorbitol mixing was continued and then the PEC was ready for coating. The PEC was stable over time.

[0058] Example 4 - Coating of paper boards

[0059] The aim was to develop a paper coating formulation, mainly composed of Woodmer® LCC polymer. Good grease barrier properties were desirable, but also a barrier against oxygen and water. The work included different compositions of coatings with different materials and ratios between the Woodmer® LCC polymer DH14 and cat-ionic starches, especially Vector from Roquette.

[0060] All developed coatings were coated on Stora Enso paper boards (Natura), dried in oven, and later characterised by the KIT-method (Tappi T559) where the paper board is treated with oil and solvent mixtures to evaluate the grease barrier properties. Kit 12 is the highest value and the test method uses a mixture of toluene and heptane and its ability to penetrate the board surface. Cobb60 was measured on certain surfaces to determine the water adsorbing properties of the coatings (figure 4). Moreover, the film forming properties, coating properties and stability of the coating were also assessed and summarized. Materials

[0061] Woodmer®: DH14 F 19 w% (Produced in pilot 20200120)

[0062] Cationic starch: Vector IC 42280-EXP-EX, Batch VCS69 20191028 42,3 w%

[0063] Cationic starch: Solcore 134P, 10 w%

[0064] Cellulose derivative: 2-Hydroxyethyl Cellulose (HEC), Mw~250,000, 6,25w%

[0065] Reference: Lignosulfonate (LS), 19 w%

[0066] Sorbitol

[0067] Ethanol

[0068] Procedure

[0069] Different amounts of Woodmer® DH14 F was added continuously to Vector during gentle mixing. Addition of sorbitol and ethanol compared to the dry weight of the formed PEC was also tested. In addition, references of each component (Woodmer® 19 w% and 37 w% and Vector 30 w%, were also made). The mixtures were coated on Store Enso papers (Natura) and thereafter dried in oven at 105 °C for 5 min. Evaluation of the different coating were made and summarised in Table 4. Reference PECs with lignosulfonate and cationic starch were also produced (table 5).

[0070] Table 4. Board coatings using different PEC formulation based on Woodmer® polymer and Vector cat-ionic starch.

[0071] Table 5. Board coatings using different PEC formulation based on Lignosulfonate from Domsjo and Vector cat-ionic starch.

[0072] From result tables, the most promising developed coating was the PEC with Vector and DH14 F (formula 14 and 16). These PEC formulation resulted in KIT 12 and they could produce good free-standing films. In Figure 3a, the precipitation in water for previous mentioned PECs and a reference PEC with lignosulfonate (LS)+Vector (formula 18) was tested. As can be seen in the figure, the Woodmer® DH14F PEC is much stronger than the PEC with LS. Figure 3a. LS-vector PEC (formula 30) precipitation in water. The right is DH14-vector PEC (formula 19) precipitation in water.

[0073] Figure 3b. Paper board samples after a cobb60 experiment. Left is DH14 coated sample that has been completely removed by the water. To the right is a PEC coated surface, which stays intact after the experiment.

[0074] Example 5 - Oxygen transmission rate (OTR) measurements

[0075] The film forming properties of the produced PECs between the Woodmer® polymer and the cat-ionic starch made it possible to determine the oxygen permeability of the material. Free standing films were produced as described below and their OTR values was measured.

[0076] Figure 4. Woodmer® - Vector films for OTR measurements

[0077] Material

[0078] Vector (Vector IC 42280-EXP-EX-LAB 4202) 41 ,7%

[0079] DH14 19,5% (DH14 produced in the pilot 202001169)

[0080] Procedure

[0081] 38,5 g DH14 (7,506 g) was added continuously to 22 g Vector (9,174 g) during gently mixing. Sorbitol was added in 10% or 20% compared to the dry weight of the formed PEC. Sonnication was used to remove as much air bubbles as possible and films were produced by casting on Petri dishes and drying over night at room temperature. OTR measurements were performed at 50%.

[0082] Sample 1 (OTR 1 ) 10% sorbitol - 4 samples

[0083] Sample 2 (OTR 2) 20% sorbitol - 5 samples

[0084] Results

[0085] Both films had good OTR values below 10 cc / (m2.day). In conclusion, the PEC films gave good OTR suitable for packaging applications.

[0086] Figure 5a. OTR film 1 Figure 5b. OTR film 2

[0087] Other Woodmer® polymers produced from different pulping process liquors were also included in this study. A Woodmer® polymer produced from the CTMP procees was used for the formation of a stable PEC with Vector cat-ionic starch.

[0088] 1. 0,5 g CTMP Woodmer® polymer was dissolved in 10 mL of water. This material was used for film formation to produce a free-standing film.

[0089] 2. 0,5 g CTMP Woodmer® polymer was dissolved in 10 mL of water. 0.5 g Vector cat-ionic starch (Based on dry weight) was added and mixed to produce PEC. This material was used for film formation to produce a free-standing film.

[0090] Result: The film 1 dissolved in water whereas the film 2 was insoluble, however it swelled in water. This proved a successful PEC with Vector cat-ionic starch.

[0091] Example 7 - TMP Woodmer® polymer - Polyethylene imine PEC

[0092] Material

[0093] Polyethylene imine, herein ‘PEI’, (Lupasol G100, 50092985, BASF) 50.0%

[0094] Woodmer® polymer BR2 (BR2 produced in the pilot sep 2011 from a Swedish TMP mill utilizing Woodmer® technology)

[0095] Procedure

[0096] Different amounts (10-20 %w) of Polyethylene Imine (Lupasol G100, 50092985, BASF) PEI was added continuously to Woodmer® polymer BR2 during gentle mixing. After that glycerol was added to the mixture to function as a plasticizer. This resulted in a solution with 20 %w drymatter content that was particle free as evaluated by visual inspection. Solvent casting to rectangular (9x9 cm) petridishes was used to create free-standing films through drying. It was noteworthy that during the last phase of drying, a cloudy gel structure was formed. However, the resulting free-standing film was visually completely transparent. The formation of the precipitate confirms that a PEC was formed during the drying process as the polymer concentration in the mixture increased.

[0097] Examule 8 - Oxygen transmission rate (OTR) measurements

[0098] The film forming properties of the produced PECs between the Woodmer® polymer BR2 and the polyethylene imine (PEI) made it possible to determine the oxygen transmission rate of the material. The transmission rate was determined according to ASTM standard D3985-02 (ASTM American Society for Testing and Mate- rials) using a Mocon Oxtran 2 / 20 (Modern Controls, Minneapolis, MN, USA) equipped with a colorimetric sensor. The samples were conditioned at 50% RH and 23°C for 3 days. The samples were cut and sealed between sheets of aluminum foil with a circular exposed area of 5cm2. The thickness was taken as the mean value of five individual measurements performed with a Mitutoyo micrometer (Takasu, Japan).

[0099] Samples 1 and 2 (Woodmer® 1 and 2) 70 % BR2, 20 % PEI and 10 % glycerol

[0100] Samples 3 and 4 (Woodmer® 3 and 4) 70 % BR2, 10 % PEI and 20 % glycerol

[0101] Thickness ( m)

[0102] Sample Average

[0103] Woodmer 1

[0104] Woodmer 2

[0105] Woodmer 3

[0106] Woodmer 4

[0107] Table 6. Woodmer® - PEI films for OTR measurements

[0108] Table 7 Woodmer® polymer BR2 - PEI film OTR measurement results 02TR, cc / (m2 24 hours)

[0109] Cell A Cell B

[0110] Woodmer 1

[0111] Woodmer 2

[0112] Woodmer 3

[0113] Woodmer 4

[0114] Table 7. Woodmer® polymer BR2 - PEI film OTR measurement results

[0115] Results

[0116] Both films had good OTR values below 10 cc / (m2.day). In conclusion, the PEC films gave good OTR suitable for packaging applications.

[0117] According to one embodiment, a PEC of the invention may be produced by a method comprising the step of treating an aqueous gel, dispersion or suspension of PEC with water. The PEC thus obtained may typically be in the form of a water insoluble precipitate and may be useful for the application as an adhesive, barrier and / or a binder.

[0118] According to one embodiment, a PEC of the invention may comprise a NHCL, e.g. the NHCL having CAS registration number 2769734-64-5, and a CP, e.g. a cationic polysaccharide such as a cationic starch, in a ratio (w / w) from 40:60 to 60:40, such as from 40:50 to 50:50 (equal amounts), e.g. 45:55 to 50:50, respectively.

[0119] According to one embodiment, a PEC of the invention may comprise a CP, e.g. a cationic polysaccharide such as a cationic starch, having a degree of substitution in the range from 0.08 to 0.9, e.g. 0.08 to 0.81 , or 0.5 to 0.9, such as from 0.6 to 0.9, e.g. 0.65 to 0.81 , or 0.5 to 0.7 or 0.7 to 0.9.

[0120] According to one embodiment, a PEC of the invention may comprise the NHCL having CAS registration number 2769734-64-5, and a CP, e.g. a cationic polysaccharide such as a cationic starch, in a ratio (w / w) from 45:55 to 50:50 (equal amounts), respectively. The CP may simultaneously have a degree of substitution in the range from 0.65 to 0.81 . Such a combination of NHCL, CP, ratio and degree of substitution may define a non-limiting parametric local maximum in which the resulting PEC after production is having an advantageous high stability as its initially formed low viscosity water dispersion. Such a stable water dispersion may be conveniently used in e.g. coating applications, yielding a desired water insoluble PEC residue upon subsequent drying.

[0121] The present invention has been described above with reference to specific examples. However, other examples than the above described are equally possible within the scope of the invention. The different features and steps of the invention may be combined in other combinations than those described.

[0122] The scope of the invention is only limited by the appended patent claims.

[0123] More generally, those skilled in the art will readily appreciate that all parameters, materials, and configurations described herein are meant to be exemplary and that the actual parameters, materials, and / or configurations will depend upon the specific application or applications for which the teaching of the present invention is / are used.

Claims

Claims1 . A water insoluble polyelectrolyte complex (PEC) comprising a negatively charged high molecular weight hemicellulose-lignin co-polymer (NHCL) and a cationic polymer (CP), wherein- said NHCL is selected from the group consisting of lignin carbohydrate complexes (LCC) from pre-hydrolysis sulphite pulping, LCC from pre-hydrolysis kraft pulping, LCC from mechanical pulping and chemical / mechanical pulping (TMP and CTMP); and- said CP is having a degree of substitution in the range of 0.08 to 0.81 , such as 0.65-0.81 , and is selected from the group consisting of cationic polysaccharides and cationic starches.

2. A PEC according to claim 1 , wherein said NHCL originates from prehydrolysis sulphite pulping.

3. A PEC according to claim 1 or 2, wherein the ratio (w / w) between said NHCL and said CP is in the range of 40:60 to 60:40, respectively, when said CP has a degree of substitution in the range of 0.08 to 0.9.

4. A PEC according to claim 3, wherein the ratio (w / w) between said NHCL and said CP is 45:55, respectively, or the relationship between these is equal amounts, when said CP has a degree of substitution in the range of 0.65-0.81 .

5. A PEC according to any one of the preceding claims, wherein- said NHCL is a compound having CAS registration number 2769734-64-5, i.e. CAS index name “Hemicellulose, polymer with sodium lignosulfonate”; and- said CP is a water-soluble cationic starch having a degree of substitution above 0.08, such as above 0.65, and a nitrogen content above 0.4%.

6. A PEC according to any one of the preceding claims, wherein- said CP is a cationic starch, is having a degree of substitution in the range from 0.65 to 0.81 and a nitrogen content in the range of 3.5 to 4.0 w%.

7. Use of a PEC according to any one of the preceding claims as a barrier material, for example in a food packaging material to improve grease and / oroxygen barrier properties, or as an adhesive or as and binder, for example in a food packaging material.

8. A method of production of a PEC according to any one of claims 1 -6, comprising the step of mixing said NHCL, at a concentration of at least 10 w%, with said CP, with a concentration of at least 10 w%, to yield said PEC as a stable PEC particle dispersions with low viscosity.

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