Shellac based binder

Abstract

A binder composition comprising an aqueous solution, shellac and an amphiphilic component; wherein the amphiphilic component is selected from a surfactant or a combination of a surfactant and casein; and wherein the amount of the amphiphilic component is at least 10wt% based on the amount of shellac but less than 30wt%.

Description

[0001] SHELLAC BASED BINDER

[0002] FIELD OF INVENTION

[0003] The present invention relates to a composition that can be used as a binder in paint. The composition is an aqueous composition comprising shellac and a surfactant.

[0004] BACKGROUND

[0005] A binder in a paint normally contains latex particles of e.g. acrylates, alkyds or polyurethanes dispersed in water. The softening temperature, Tg, (also termed glass transition temperature) of these latexes is normally high (over room temperature) in order to have a final coating that is hard and non-tacky.

[0006] When applying such a dispersion on a surface the water evaporates and the particles close pack. However, a problem is that the fluidity of the particles is not sufficient to merge the particles to form a steady film. In order to address this problem a softener, or coalescing agent, is normally added. As the water evaporates the concentration of the coalescing agent increases and eventually enters the latex particles. The effect is that the latex particles deform and eventually the particles coalesce and lose their identity - a film is formed.

[0007] In this manner a continuous film, holding the paint pigments, is formed. As the film continues to dry the coalescing agent evaporates leaving a hard paint surface. This process may take months, depending on the vapor pressure of the coalescing agent and the surrounding environment. Presence of coalescing agents in paints may result in high levels of VOC, Volatile Organic Compounds, which may be harmful or even toxic.

[0008] Shellac or lacca is a biobased resin produced by lac bugs and contains mainly aleuritic acid, jalaric acid, shelloilic acid and other waxes. The natural shellac is purified to remove unwanted products. Today shellac is used in a variety of applications ranging from furniture polish to nail polish, to coating of sweets.

[0009] A problem with a shellac-based composition is that the formed film is brittle, and it cracks and also the compositions have a tendency of not being stable over time.

[0010] Casein is a biobased protein that has good adhesive properties, but films of casein have a long drying-time, and the formed film is brittle and not water resistant. Casein also tends to react with the underlying surface giving a superb adhesion. Further, casein is unstable when dissolved in water, probably due to polymerization.

[0011] SUMMARY OF INVENTION

[0012] The aim of the present invention is to overcome the drawbacks of prior art and provide a biobased binder composition which has low, or zero, level of VOC and is stable with time. When the binder is applied to a surface it provides a film, coating or layer which adheres well to the surface, and has a reduced, or no, tendency to crack and discolour.

[0013] In a first aspect the present invention relates to a composition comprising an aqueous solution, shellac and a surfactant; wherein the surfactant is selected from casein, an amphiphilic component or a combination thereof; and wherein the amount of the surfactant is at least 10wt% based on the amount of shellack but less than 30wt%

[0014] In a second aspect the present invention relates to a method of preparing the composition according to the present invention wherein the method comprises: a. Preparing a surfactant solution by dissolving surfactant in a first aqueous solution at a surfactant dissolving temperature, with proviso that the pH of the surfactant solution is at least 8 when the surfactant is casein or a combination of casein and an amphiphilic component, b. Preparing a shellack solution by dissolving shellack in a second aqueous solution at a shellack dissolving temperature and at a pH of at least 8; and c. Mixing the surfactant solution with the shellack solution.

[0015] In a third aspect the present invention relates to a composition obtainable by the method according to the present invention.

[0016] ITEMIZED EMBODIMENTS

[0017] In one embodiment the composition is a binder composition comprising an aqueous solution, shellac and an amphiphilic component; wherein the amphiphilic component is selected from a surfactant or a combination of a surfactant and casein; and wherein the amount of the amphiphilic component is at least 10wt% based on the amount of shellac but less than 30wt%.

[0018] In one embodiment below the water is selected from tap water or deionized water, preferably deionized water.

[0019] In one embodiment according to any of the aspects the composition further comprises particles of latex and wherein the latex surface preferably comprises sulphate groups, carboxylic acid groups, hydroxyl groups or ester groups; and wherein the particles of latex preferably further comprises an additional surfactant.

[0020] In one embodiment according to any of the aspects the latex is made of a polymer having a glass transition temperature of not higher than 25°C, more preferably not higher than 22°C.

[0021] In one embodiment according to any of the aspects the composition comprises a softener preferably selected from polypropylene glycol, polyethylene glycol, gelatine, glycerol, glycerol triacetate, triacetin or trimethyl citrate or a combination thereof.

[0022] In one embodiment according to any of the aspects the softener is selected from polypropylene glycol, polyethylene glycol or a combination thereof, wherein the molecular weight of the polypropylene glycol or the polyethylene glycol preferably is at least lOOg / mol, more preferably at least 300g / mol but preferably lower than l,000g / mol, more preferably lower than 700g / mol, more preferably the molecular weight is about 400g / mol.

[0023] In one embodiment according to any of the aspects the amount of softener is at least 10wt% based on the total amount of shellac, preferably at least 15wt% but preferably less than 30wt% more preferably the amount is about 25wt%.

[0024] In one embodiment according to any of the aspects the amount of shellac is at least 20wt% of the composition, preferably at least 25wt%, more preferably at least 30wt% but preferably not more than 45wt%, preferably not more than 40wt%.

[0025] In one embodiment according to any of the aspects the amount of the amphiphilic component is at least 15wt% but preferably less than 30wt% more preferably less than 25wt%, more preferably the amount is about 20wt% based on the amount of shellac. In one embodiment according to any of the aspects the amount of casein is at least 5wt% but preferably less than 25wt%, more preferably the amount is about 20wt% based on the amount of shellac.

[0026] In one embodiment according to any of the aspects the surfactant is a combination an amphiphilic component and casein and wherein the combination comprises 20 to 28 wt% of the amphiphilic component and 2 to 10wt% of casein based on the amount of shellac, preferably 25-28wt% of the amphiphilic component and 2 to 5wt% of casein.

[0027] In one embodiment according to any of the aspects the composition further comprises vegetable oil wherein the oil preferably comprises at least 60wt% of linoleic acid, preferably at least 70wt%, more preferably at least 80wt%, and preferably the oil comprises less than 10wt% of linolenic acid, preferably less than 5wt%, more preferably less than lwt%.

[0028] In one embodiment according to any of the aspects the vegetable oil is thistle or safflower oil.

[0029] In one embodiment according to any of the aspects the amphiphilic component is a combination of casein and a surfactant, and wherein the surfactant preferably is triglyceride or fatty acid based or is a polyoxyethylene sorbitan based compound preferably selected from polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate.

[0030] In one embodiment according to the present invention the amphiphilic component is polyoxyethylenesorbitan trioleate. In one embodiment according to the present invention the amphiphilic component is a combination of a surfactant and casein and wherein the combination comprises 20 to 28 wt% of the surfactant and 2 to 10wt% of casein based on the amount of shellac, preferably 25-28wt% of the surfactant and 2 to 5wt% of casein.

[0031] In one embodiment of the present invention the amphiphilic component is a combination of a surfactant and casein, wherein the surfactant is triglyceride or fatty acid based; and wherein the composition further comprises a softener wherein the softener is polypropylene glycol.

[0032] In one embodiment the method is to prepare a binder composition wherein the method comprises: a. Preparing an amphiphilic component solution by dissolving the amphiphilic component in a first aqueous solution at a amphiphilic dissolving temperature, with proviso that the pH of the surfactant solution is at least 8 when the amphiphilic component is a combination of casein and a surfactant, b. Preparing a shellac solution by dissolving shellac in a second aqueous solution at a shellac dissolving temperature and at a pH of at least 8; and c. Mixing the amphiphilic component solution with the shellac solution.

[0033] In one embodiment according to the present invention the composition has a pH of at least 8.

[0034] In one embodiment according to any of the aspects the surfactant is a combination of casein and a surfactant and wherein the pH of the solution is at least 8.2 and preferably adjusted using borax, bicarbonate, sodium hydroxide, ammoniac or ammonium hydroxide (NH4OH).

[0035] In one embodiment according to any of the aspects the ampiphilic component dissolving temperature is 40-100°C, preferably 40-60°C when the ampiphilic component is casein or a combination of casein and a surfactant, or wherein the amphiphilic dissolving temperature is lower than 40°C, preferably 20-30°C when the amphiphilic component is a surfactant.

[0036] In one embodiment according to any of the aspects the shellac dissolving temperature is 40-90°C, preferably 60-90°C.

[0037] In one embodiment according to any of the aspects an oil is added to the surfactant solution.

[0038] In one embodiment according to any of the aspects an amphiphilic component and / or a softener is added to the shellac solution.

[0039] In one embodiment according to any of the aspects latex particles are mixed with the shellac solution.

[0040] In one embodiment according to any of the aspects the aqueous solution is water and preferably purified water preferably selected from deionized water or distilled water. In one embodiment according to any of the aspects the water content in the aqueous solution is preferably at least 80wt%, more preferably at least 90wt%, more preferably at least 95wt%, more preferably about 100wt%.

[0041] In one embodiment of the present invention an oil is added to the amphiphilic component solution and wherein an additional surfactant and / or a softener is added to the shellac solution; and preferably wherein latex particles are mixed with the shellac solution.

[0042] In one embodiment according to any of the aspects the solids content in the composition is preferably at least 25wt%, more preferably at least 305wt%, but preferably not more than 45wt0%, preferably not more than 40wt%.

[0043] All embodiments are applicable to all aspects and may be combined unless otherwise stated.

[0044] DETAILED DESCRIPTION

[0045] In the present invention the term “casein” encompasses asi-casein, asa-casein, |3- casein and K-casein or a mixture of two or more thereof.

[0046] Amphiphilic components are components that have both hydrophilic and hydrophobic regions or sections. As the skilled person knows, some amphiphilic components may act as surfactants depending on their chemical structure.

[0047] The composition

[0048] The composition according to the present invention is a composition comprising an aqueous solution, shellac and one or more amphiphilic compounds. Surfactants and casein are preferred amphiphilic compounds.

[0049] A problem seen when using casein is that the viscosity of the composition increases with time. What the present inventors found was that if the amount of casein to shellac is kept at a relatively low value this tendency is significantly reduced or even eliminated. Hence, what the present inventors found was that an amount of amphiphilic component of at least 10wt% but not more than 30wt% based on the amount shellac, has shown to reduce, or even eliminate, the increase in viscosity with time. Preferably the amount of amphiphilic component is at least 15wt% but preferably not more than 25wt%, more preferably the amount is about 20wt%. The casein and the surfactant have the function of providing the wanted viscosity of the composition but also to act as emulsifying agents when the composition further comprises an oil. Casein is a mixture of four proteins, that act as emulsifying agents in the composition, especially when the composition comprises an oil. Casein also renders good adhesion properties towards the substrate. An advantage of using a combination of a surfactant and casein is that the stability of the composition increases in comparison with only a surfactant and the effect of viscosity increase with time is reduced or eliminated by the addition of a surfactant in comparison with only casein. When the amphiphilic component is a combination of a surfactant and casein the amount of each component is preferably 2 to 28wt% based on the amount shellac. In one embodiment the combination comprises 20 to 28 wt% of the surfactant and 2 to 10wt% of casein, preferably 25-28wt% of the surfactant and 2 to 5wt% of casein. This was shown to result in compositions with suitable viscosity and that gave stable dispersions with respect to flocculation and also good films with respect to homogeneity, adhesion and water resistance. High amounts of the amphiphilic component reduce the obtained films water resistance and too low amount results in flocculation in the composition.

[0050] The surfactant may be a component which can form liposomes, or vesicles, and has a molecular weight of not more than 3,000g / mol, preferably not more than 2,000g / mol. The amphiphilic component forms liposomes where the shellac is partly found inside the liposomes and partly outside and thereby is partly protected. Preferably the surfactant and the additional surfactant are based on a triglyceride or fatty acid preferably with a polyoxyethylene chemically attached. Alternatives are using lipids that form liposomes on agitation. Other suitable surfactants are polyoxyethyelene compounds preferably selected from polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate. These low molecular weight amphiphilic components are used to stabilize the colloidal structure especially when the composition comprises emulsion, latex and / or pigment.

[0051] The surfactants may also act as wetting agents by adsorbing on the pigment particles, thus providing a more hydrophilic surface making the particles more easily dispersible in water. Furthermore, when the composition comprises an oil the amphiphilic components further act as emulsifiers resulting in small and stable oil drops. Furthermore, the amphiphilic components act as wetting agents towards the substrate, when the system is applied to a surface, rendering a good adhesion towards the surface. The present inventors have confirmed that a combination of casein and amphiphilic components provides high stability and good adhesion properties. Finally, by using amphiphilic components based on triglyceride or fatty acids the renewable content of the final composition increases.

[0052] Shellac acts as a binder in the composition, forming the films or coatings. In order to provide good viscosity of the composition and the wanted properties of the obtained film or coating, the dry content of the total composition is preferably at least 10wt% in the composition. A further advantage of shellac is that it has biocidal properties and has even been shown to be carbon dioxide negative. Higher amounts of shellac increase the viscosity to levels that the formulation cannot be handled. With increasing shellac content the risk of cracks in the obtained film also increases.

[0053] The aqueous solution is preferably water of any suitable purity but may comprise other solvents such as alcohol in minor amounts. Preferably the water is purified, preferably deionized or distilled. Using purified, deionized, water increases the stability and / or repeatability since tap water may contain components, such as calcium or magnesium ions, that may affect the compositions properties. The water content in the aqueous solution is preferably at least 80wt%, more preferably at least 90wt%, more preferably at least 95wt%, more preferably about 100wt%.

[0054] When the composition comprises particles of latex, the latex preferably comprises polyethylene oxide groups, sulphate groups, carboxylic acid groups, hydroxyl groups or ester groups as well as stabilizing surfactants at the surface of the particles. Using latex comprising said functional groups allows reaction between hydroxyl or carboxyl groups on the shellac and the functional groups on the latex surface. By using a latex made of a polymer having a low glass transition temperature (Tg) the latex may provide a softening effect. In a preferred embodiment the latex is made of a polymer having a Tgof not higher than 25°C, more preferably not higher than 22°C. This reduces the tendency for the formed film or coating to crack when dried and reduces the need for softeners. Latex particles usually comprise a surfactant that will be adsorbed on the particle surface. These surfactants, or additional surfactants, may be any suitable surfactant but may be selected from surfactants as disclosed above.

[0055] Shellac and casein both have a rather high Tg, thus compensating the low softening temperature of the latex. In fact, it is possible to calculate the final softening temperature Tg,mix through following equation:

[0056] Where <Pii and Tg;iis the volume fraction and softening temperature of species i.

[0057] A softener may also be added to the composition in order to reduce the brittleness of the formed film or coating. Without being bound by theory, the softener dilutes the composition and reduces the number of cross-links or secondary bonds between the shellac molecules, or the shellac and the latex particles. Softener is preferably selected from polypropylene glycol, polyethylene glycol, gelatine, glycerol, glycerol triacetate, triacetin or trimethyl citrate or a combination thereof. Preferably the softener is polypropylene glycol or polyethylene glycol with a molecular weight of 100 to lOOOg / mol. What the present inventors have shown is that a molecular weight of at least 300g / mol but lower than 700g / mol, more preferably the molecular weight is about 400g / mol shows the best results. The reason is that then the softener is large enough to interact and separate the interacting molecules whereas too large molecules tend not to be soluble in the shellac. It is further known that polypropylene glycol is not as water soluble as polyethylene glycol which would reduce the obtained film’s or the coating’s water sensibility. Further, polypropylene glycol has a lower vapour pressure, compared to polyethylene glycol, i.e. it evaporates more slowly, and thereby results in a lower VOC value directly on application.

[0058] Depending on the wanted hardness and flexibility of the film the amount of softener is adjusted, see equation above. The amount of softener is around 10 to 30wt% of the combined amount casein and shellac, preferably 15-25wt%, more preferably around 20wt%.

[0059] By adding a vegetable oil to the composition, the renewable content increases and makes the composition easier to apply to a substrate. For example, the composition is more easily spread when applied with a brush or roller. The oil is preferably a drying or semi-drying oil. Linseed oil is a commonly used drying oil in paints but has the disadvantage of discoloration with time, forms acetaldehydes which evaporates and increases the VOC, and smell when the oxidation process is slow or not completed. The latter is a problem when using paints based on linseed oil in areas where the circulation or the access to oxygen is limited, for example indoors. Furthermore, linseed oil may contain heavy metals, used as an accelerator for the drying process. As an alternative the present inventors have found that a preferred semi-drying oil is thistle oil or safflower oil. The fatty acid composition of the vegetable oil, according to the present invention, should preferably comprise at least 60wt% of linoleic acid, preferably at least 70wt%, more preferably at least 80wt%, and preferably the oil comprises less than 10wt% of linolenic acid, preferably less than 5wt%, more preferably less than lwt%. This provides sufficient drying time but does not discolour with time, no smell and the composition is easy to apply. When the composition comprises an oil the amount of amphiphilic component is preferably at least 20wt% of the amount of the oil in order to facilitate sufficient emulsification and colloidal stability of the oil. The amount is more preferably at least 25wt% but preferably less than 50wt%. In order to obtain suitable viscosity the amount of oil in the composition is preferably 3-10wt%, preferably 5-8wt%.

[0060] The present composition may further comprise filler and additives. Suitable fillers are for example kaolinite, quarts and mica. Additives may be thickeners, biocides and / or preservatives.

[0061] The present composition which may be used as a binder which provides films that are water resistant. A further advantage of the present invention is that the content of renewable compounds in the composition may be high and may be easily adapted. When the composition does not comprise latex particles the content of renewable compounds may be nearly 100wt% when measured as the amount of biobased carbon (Cl 4), but at least 80wt%, preferably at least 90wt%. Compositions comprising latex particles may have a content of renewable compounds of up to 30wt%, such as 10-25wt%.

[0062] METHOD OF PREPARING COMPOSITION

[0063] When preparing the composition of the present invention at least two solutions are prepared, an amphiphilic component solution with the amphiphilic component and a shellac solution. When the amphiphilic component is a combination of a surfactant and casein the amphiphilic component is dissolved in a first aqueous solution at a amphiphilic dissolving temperature which preferably is 40-100°C, preferably 40-60°C. When the amphiphilic component is a surfactant the surfactant is dissolved in a first aqueous solution at an amphiphilic dissolving temperature which preferably is lower than 40°C, preferably 20-30°C.

[0064] The pH of the amphiphilic component solution is at least 8 when the amphiphilic component is a combination of casein and a surfactant. In a preferred embodiment the pH is at least 8.2 but preferably not higher than 9, preferably not higher than

[0065] 8.5.

[0066] The shellac solution comprises shellac dissolved in a second aqueous solution at a pH of at least 8 at a shellac dissolving temperature which preferably is 40-90°C, preferably 60-90°C, more preferably about 80°C. The pH of the shellac solution is preferably at least 8.2 but preferably not higher than 9, and preferably not higher than 8.5. Lower pH results in difficulties in dissolving the shellac and higher pH results in precipitation of the shellac. A problem with shellac is that it ages quite rapidly when stored dry and is very hard to handle and to dissolve. Using a high temperature in combination with a high pH when preparing the shellac solution allows the use of aged shellac which otherwise would have been discarded.

[0067] The pH of the two aqueous solutions may be adjusted using any suitable base or alkali salt but preferably using borax, bicarbonate, sodium hydroxide, ammoniac or ammonium hydroxide (NH4OH). Ammoniac and ammonium hydroxide are preferred since they do not form unwanted byproducts.

[0068] When using an oil in the composition, said oil is preferably added to the amphiphilic component solution and emulsified. After emulsification, for a predetermined time, a stable emulsion is obtained.

[0069] Softener is preferably added to the shellac solution under stirring.

[0070] The two solutions are then mixed at a suitable ratio to obtain the wanted proportions of the components. Latex particles are preferably mixed with the formed mixture of the two solutions to form a final product, i.e. a binder.

[0071] EXAMPLES

[0072] Example 1

[0073] A composition comprising shellac (30wt%), casein(lwt%) safflower oil (9wt%), and deionized water, q.s. (quantum satis), was prepared according to the present invention.

[0074] The composition was analysed by Beta Analytic Inc. using C14 to determine the degree of biobased carbon. The result showed that the composition had a 100% biobased carbon content. The composition formed a nice smooth film when applied to a wood substrate surface.

[0075] Example 2

[0076] A study was performed in order to investigate the effect of using different surfactants and the effect of using purified water.

[0077] Five different compositions were prepared all comprising water, shellac and amphiphilic component (casein and / or Tween 85). Tween 85 is a surfactant (polyoxyethylenesorbitan trioleate) .

[0078] Composition 1: shellac, 30wt%, casein, lwt%, Tween 85, 7wt% and safflower oil, 9wt% and deionized water, q.s

[0079] Composition 2: shellac, 30wt% casein, lwt% and safflower oil, 9wt% and deionized water, q.s. (same as example 1)

[0080] Composition 3: shellac, 30wt%, casein, lwt%, Tween 85, 7wt% and safflower oil, 9wt% and tap water q.s

[0081] Composition 4: shellac 30wt%, Tween 85,7wt%, safflower oil, 9wt% and deionized water, q.s

[0082] Composition 5: shellac, 30wt% and Tween 85, 7wt% and deionized water, q.s.

[0083] The compositions were analyzed with respect to separation and later applied to a glass surface and dried. The film was analysed (i) visually regarding appearance and (ii) chemically with respect to water resistance.

[0084] Results

[0085] When tap water is used the colloidal stability of the systems is not as good as when distilled water is used.

[0086] When no surfactant (Tween 85) was used the obtained film was uneven and not homogenous.

[0087] When no oil or casein was used the obtained film was fully transparent. Still, the oil made the obtained film more water resistant and also the formulation is more easily applied.

[0088] Example 3 Two binder compositions were prepared using the composition according to the present invention (example 2) where polypropylene glycol (400g / mol) was used as softener in one formulation and polyethylene glycol (400g / mol) was used in the other. A layer of binder was applied to a glass surface.

[0089] VOC Emission test was conducted by an external company (Eurofins Product Testing A / S).

[0090] Results

[0091] The tests showed that paint comprising polyethylene glycol had a much higher VOC (after 3 days and after 28 days) than the paint comprising polypropylene glycol.

[0092] Example 4

[0093] A comparison test was conducted to see the effect of using another surfactant, i.e. an alkyl glucoside.

[0094] A composition was prepared according to example 2 above. The present invention comprising water, shellac (30wt%), casein (lwt%), alkyl glucoside (7wt%) and safflower oil (9wt%).

[0095] The obtained composition showed low colloidal stability by separating in different phases.

Claims

Claims1. A binder composition comprising an aqueous solution, shellac and an amphiphilic component; wherein the amphiphilic component is selected from a surfactant or a combination of a surfactant and casein; and wherein the amount of the amphiphilic component is at least 10wt% based on the amount of shellac but less than 30wt%.

2. The binder composition according to claim 1 wherein the composition further comprises particles of latex and wherein the latex surface preferably comprises polyethylene oxide groups, sulphate groups, carboxylic acid groups, hydroxyl groups or ester groups.

3. The binder composition according to claim 2 wherein the latex is made of a polymer having a glass transition temperature of not higher than 25°C, more preferably not higher than 22 °C.

4. The binder composition according to any one of claim 1 to 3 wherein the composition comprises a softener preferably selected from polypropylene glycol, polyethylene glycol, gelatine, glycerol, glycerol triacetate, triacetin or trimethyl citrate or a combination thereof; and wherein the amount of softener preferably is at least 10wt% based on the total amount of shellac, preferably at least 15wt% but preferably less than 30wt%, more preferably the amount is about 25wt%.

5. The binder composition according to any one of the preceding claims wherein the softener is selected from polypropylene glycol, polyethylene glycol or a combination thereof, wherein the molecular weight of the polypropylene glycol or the polyethylene glycol preferably is at least lOOg / mol, more preferably at least 300g / mol but preferably lower than l,000g / mol, more preferably lower than 700g / mol, more preferably the molecular weight is about 400g / mol.

6. The binder composition according to any one of the preceding claims wherein the amount of shellac is at least 20wt% of the composition, preferably at least 25wt%, more preferably at least 30wt% but preferably not more than 45wt%, preferably not more than 40wt%.

7. The binder composition according to any of the preceding claims wherein the amount of the amphiphilic component is at least 15wt% but preferably less than 30wt% more preferably less than 25wt%, more preferably the amount is about 20wt% based on the amount of shellac.

8. The binder composition according to any one of the preceding claims wherein the composition further comprises vegetable oil wherein the oil has a fatty acid composition preferably comprising at least 60wt% of linoleic acid, preferably at least 70wt%, more preferably at least 80wt%, and preferably the oil comprises less than 10wt% of linolenic acid, preferably less than 5wt%, more preferably less than lwt%; wherein the vegetable oil preferably is thistle or safflower oil.

9. The binder composition according to any of the preceding claims wherein the amphiphilic component is a surfactant or, a combination of casein and a surfactant, and wherein surfactant preferably is triglyceride or fatty acid based or is a polyoxyethylene sorbitan based compound preferably selected from polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, more preferably wherein the surfactant component is polyoxyethylenesorbitan trioleate.

10. The binder composition according to any one of the preceding claims wherein the amphiphilic component is a combination of a surfactant and casein and wherein the combination comprises 20 to 28 wt% of the surfactant and 2 to 10wt% of casein based on the amount of schellac, preferably 25-28wt% of the surfactant and 2 to 5wt% of casein.

11. The binder composition according to any one of the preceding claims wherein the amphiphilic component is a combination of a surfactant and casein, wherein the surfactant is triglyceride or fatty acid based; and wherein the composition further comprises a softener wherein the softener is polypropylene glycol.

12. Method of preparing the binder composition according to any one of claim 1 to 11 wherein the method comprises: a. Preparing an amphiphilic component solution by dissolving the amphiphilic component in a first aqueous solution at an amphiphilic dissolving temperature, with proviso that the pH of the surfactant solution is at least 8 when the amphiphilic component is a combination of casein and a surfactant, b. Preparing a shellac solution by dissolving shellac in a second aqueous solution at a shellack dissolving temperature and at a pH of at least 8; and c. Mixing the amphiphilic component solution with the shellac solution.

13. The method according to claim 12 wherein the amphiphilic component is a combination of casein and a surfactant and wherein the pH of the amphiphilic component solution and / or the shellac solution is at least 8.2 and preferably adjusted using borax, bicarbonate, sodium hydroxide, ammoniac or ammonium hydroxide (NH4OH).

14. The method according to claim 12 or 13 wherein the amphiphilic dissolving temperature is 40-100°C, preferably 80-100°C when the amphiphilic component is a combination of casein and a surfactant, or wherein the amphiphilic dissolving temperature is lower than 40°C, preferably 20-30°C when the amphiphilic component is a surfactant.

15. The method according to any one of claim 12 to 14 wherein the shellac dissolving temperature is 40-90°C, preferably 60-90°C.

16. The method according to any one of claim 12 to 15 wherein an oil is added to the amphiphilic component solution and preferably wherein an additional surfactant and / or a softener is added to the shellac solution; and preferably wherein latex particles are mixed with the shellac solution.

17. The method according to any one of claim 12 to 16 wherein the aqueous solution is water and preferably purified water preferably selected from deionized water or distilled water.

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