Biopolymer compositions and their use as powder coatings - Patents.com

Abstract

The present invention relates to packaging materials having coatings made from biopolymer compositions. The present invention also relates to methods of providing barrier properties for packaging materials by using the above-mentioned compositions. In particular, the present invention relates to coating porous materials with compositions comprising biopolymers formed by the reaction product of a biodegradable polyester and a siloxane precursor.

Description

[Technical Field]

[0001] BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a biopolymer composition suitable for use as a coating for porous substrates, thus forming packaging materials. The present invention also relates to a method of providing barrier properties for packaging materials by coating. [Background technology]

[0002] Description of Related Art Barrier properties are required in many applications, especially packaging applications such as packaging materials for food, cosmetics, drugs, etc. Proper barrier properties protect the product inside the package from light, oxygen, and moisture, preventing contamination. Additionally, barrier properties prevent undesired leaching of the product outside the package.

[0003] Food packaging materials made from paper or cardboard typically have a polymeric coating to improve their barrier properties and protect the product. Most typically, this coating is made from a fossil-based thermoplastic resin, such as polyethylene. While polyethylene has many desirable properties, such as flexibility and heat sealability, it has the disadvantage of not being biodegradable or compostable.

[0004] The use of biopolymers is an attractive alternative to these plastic coatings, and biodegradable multilayer laminate films have therefore been developed for coating different packaging materials. Metals (e.g., aluminum or tinplate), glass, polymers (e.g., PP, PE, PET, or PVDC), and polymers coated with vaporized thin metal or oxide films, or combinations thereof, are commonly used as components for these structures. These known multilayer films can be biobased or partially biobased, and they can be biodegradable or non-biodegradable. While the use of renewable resources and biodegradability can solve some problems, the lamination process generates a lot of waste material, making it a less sustainable method. In addition, multilayer structures are very problematic from a recycling perspective, where it is important to be able to identify and separate the polymer grades used. Furthermore, there is still room for improvement in the barrier properties of packaging coatings.

[0005] Attempts have been made to find alternative methods for laminating films. One coating method used is powder coating, in which the coating material is in the form of solid, particulate (powder) particles, thereby eliminating the need for solvents to carry the coating material onto the substrate being coated. Such processes emit low volatile organic compounds (VOCs). Typically, the powder coating material is a thermosetting or thermoplastic powder that is applied to the substrate using various powder coating techniques, after which the coating is cured and the product is cooled to solidify the coating.

[0006] Several patents also present powder coating compositions capable of forming thin, water-resistant coatings on metal or glass substrates. U.S. Pat. No. 6,274,672 presents a powder coating composition containing a functional polysiloxane. The powder coating composition comprises a solid particle film-forming mixture of a polymer containing reactive functional groups, a curing agent, and an organic polysiloxane. U.S. Pat. No. 5,227,435 discloses a method for preparing a silicone-modified polyester resin and a powder coating composition containing the same. The method involves condensing a silicone compound with an alcohol, reacting the resin thus prepared with an acidic compound in the presence of an esterification catalyst, and finally reacting the resin thus prepared with trimellitic anhydride, thereby obtaining a polyester resin with a low melting point, a low softening point, and excellent storage stability.

[0007] Compared to metals and glass, the advantages of polymers include their low weight and the small amount of material required. Also, due to ecological concerns, the importance of bio-based and recyclable polymers is increasing significantly. However, due to their structure and permeability to gases and moisture, polymers cannot meet the very high barrier properties required in some applications, such as high humidity and high temperature conditions. This is particularly true for bio-based and recyclable polymers. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 6,274,672 [Patent Document 2] U.S. Patent No. 5,227,435 Summary of the Invention [Problem to be solved by the invention]

[0009] Summary of the Invention The present invention aims to overcome at least some of the problems of the prior art.

[0010] It is an object of the present invention to produce a novel type of packaging material having a biopolymer coating composition, which packaging material is particularly suitable for packaging food, cosmetics, and the like. [Means for solving the problem]

[0011] Thus, according to a first aspect, the present invention relates to a coating composition, in particular a powder coating composition, comprising a biopolymer formed by the reaction product of a biodegradable polyester and a siloxane precursor.

[0012] According to a second aspect, the present invention relates to a packaging material comprising a porous substrate coated with a biopolymer composition as described above.

[0013] According to a third aspect, the present invention relates to a method for producing a packaging material by coating a porous substrate with the biopolymer composition described above.

[0014] The present invention is therefore based on the idea of ​​utilizing a pulverized thermoplastic biodegradable polymeric composition as a thin, flexible, biodegradable coating layer on a porous substrate. The biopolymer powder composition of the present invention is obtained by reacting a polyester, preferably a biodegradable polyester, with a siloxane precursor. The biopolymer thus obtained is pulverized to form a powder, which is applied to a substrate and cured.

[0015] The powder coating composition of the present invention allows for the formation of a thin, flexible coating layer, preferably having barrier properties, particularly against water vapor and oxygen, by combining a biodegradable polyester with a siloxane precursor. The siloxane precursor provides the composition with improved barrier properties, facilitating the leveling of the coating on the surface of the substrate, thereby resulting in better surface quality.

[0016] The coating layer formed by the powder composition of the present invention can be a single layer or a multi-layer coating. In one embodiment, the powder composition of the present invention provides a single layer coating with good barrier properties. A single layer coating is thinner than a multi-layer coating, and therefore requires fewer raw materials to form a uniform coating, making it more economical and ecological. A thinner coating layer also provides improved flexibility of the coating.

[0017] The invention is characterized, inter alia, in what is stated in the independent claims, Some particular embodiments are defined in the dependent claims. [Effects of the Invention]

[0018] Several advantages are achieved using the present invention. In particular, the present invention provides packaging materials with coating compositions that have good barrier properties combined with biodegradability and / or recyclability. Thus, the present invention solves at least some of the problems of polymer structures that suffer from gas and moisture permeability, since the siloxane precursor imparts improved barrier properties to the composition. Furthermore, since the material is suitable for use as a single-layer coating, multi-layer structures are not required. In particular, the present invention provides good coating compositions for porous or other liquid- and / or gas-permeable substrates used as packaging materials.

[0019] The material composition of the present invention is suitable for use as a relatively thin coating layer for both rigid and flexible substrates. By applying the composition of the present invention to bio-based, biodegradable, recyclable, and / or compostable substrates, the present invention ensures the recyclability of the entire package in accordance with circular economy requirements.

[0020] Furthermore, relatively low temperatures, such as temperatures in the range of 20 to 150° C., can be used when coating substrates with the powder compositions of the present invention, which are particularly suitable for paper and cardboard type substrates. Low temperatures make it possible to avoid darkening and / or yellowing of the substrate.

[0021] Next, embodiments will be considered in more detail. DETAILED DESCRIPTION OF THE INVENTION

[0022] [Embodiment] The term "liquid state" in this context also includes solutions. Thus, according to the present invention, a material is in a liquid state or at least dispersed in a medium, preferably a solvent, when it is a liquid, such as a melt, achieved by heating the material above its melting temperature.

[0023] "Room temperature" means a temperature of about 15 to 30°C, especially 15 to 25°C, for example about 23°C.

[0024] As used herein, the term "about" refers to a value that is ±5% of the stated value. As used herein, the term "about" refers to an actual given value, and refers to an approximation to such a given value that would be reasonably inferred by one of ordinary skill in the art, including approximations based on experimental and / or measurement conditions for such a given value.

[0025] Unless otherwise specified, the term "molecular weight" or "average molecular weight" refers to the number average molecular weight ("M n Unless otherwise stated, number average molecular weights are measured by GPC (gel permeation chromatography) against polystyrene standards in the context of the present invention.

[0026] In the following, the term "siloxane precursor solution" is used generally to describe the liquid state of the siloxane precursor. In these contexts, the term solution includes all types of liquid states mentioned above.

[0027] In the present context, the term "biodegradable," as used in reference to a material such as a polyester, a biopolymer composition, or a coating composition, has its conventional meaning, particularly when applied to its organic portion, of a material that can be broken down (decomposed) by the action of microorganisms, such as bacteria or fungi, or both. Degradation can proceed via aerobic and anaerobic processes, typically ultimately yielding carbon dioxide from the organic material. Biodegradation generally occurs in the presence of water. Biodegradation of organic matter can be affected by ambient temperature and pH and can be complete in a period of days to months or even years.

[0028] The present invention relates to a packaging material obtained by coating a porous substrate with a powder composition containing a biopolymer formed by the reaction product of a biodegradable polyester and a siloxane precursor.

[0029] In one embodiment, the packaging material comprises a coated porous substrate, which is coated with a melt layer comprising, consisting of, or consisting essentially of a biopolymer formed by the reaction product of one or more biodegradable polyesters and one or more siloxane precursors.

[0030] In one embodiment, the coating of the porous substrate is obtained by fusing a powder coating composition applied onto the surface of the porous substrate.

[0031] In one embodiment, the coating is formed by a single layer.

[0032] In one embodiment, the coating provides a barrier property to the packaging material, in particular the coating provides a barrier property selected from the group of a liquid barrier, a gas barrier, an oil barrier, a grease barrier, and combinations thereof.

[0033] According to one preferred embodiment, the powder composition provides barrier properties to the packaging material, particularly barrier properties against water vapor and oxygen.

[0034] The biopolymer contained in the powder composition is preferably a biodegradable thermoplastic biopolymer having a single-phase structure. In the present invention, the term "single-phase" refers to a material of uniform composition throughout that cannot be mechanically separated into different materials. The formed single-phase biopolymer is based on the interaction, i.e., chemical bonds such as covalent bonds, between the polyester and siloxane and the formed biopolymer.

[0035] The substrate to be coated can be any porous material. According to the present invention, the term "porous" relates to a material that is permeable to gases, liquids, oils or fats or combinations thereof. Typically, the porous material is provided in the form of a sheet, board, plate or web.

[0036] Examples of porous materials for use in embodiments of the present technology include paper and cardboard, hi one embodiment, the porous material comprises a fibrous material, typically in the form of a sheet, board, plate, or web.

[0037] According to one preferred embodiment, the substrate is a bio-based, biodegradable, recyclable, repulpable, and / or compostable material.

[0038] "Bio-based substrates" generally refer to materials derived from biological materials such as biomass (e.g., carbohydrate materials, lignocellulosic materials, especially the formation of fibrous materials), proteinaceous materials, and lipid-containing materials, and combinations thereof. Typically, such materials can be biodegradable, recyclable, repulpable, and / or compostable.

[0039] Thus, in one embodiment, the porous material comprises natural fibers such as lignocellulosic or cellulosic fibers or a combination thereof.

[0040] In one preferred embodiment, the porous material or substrate is a bio-based substrate, including fibrous sheets, webs or bodies, particularly sheets or webs of cellulosic or lignocellulosic materials such as paper and paperboard.

[0041] Thus, in one embodiment, the substrate comprises 50 to 100% by weight, in particular 75 to 100% natural fibers, such as cellulosic or lignocellulosic fibers or a combination thereof, calculated on the total weight of fibrous material in the substrate.

[0042] In one embodiment, the porous material comprises a combination of natural and synthetic fibers, such as a nonwoven material. Examples of synthetic fibers include regenerated fibers, such as fibers produced by the viscose process, or Lyocell or other synthetic fibers, which include materials derived from polysaccharides. Typically, the nonwoven material comprises 10-75% by weight of natural fibers and 90-25% by weight of natural fibers. Additionally, the nonwoven material typically contains at least one binder, e.g., a synthetic binder such as latex.

[0043] In one embodiment, the porous material comprises a plastic, i.e., a thermoplastic material.

[0044] In one embodiment, the porous material comprises a biopolymer, in particular a thermoplastic polymer (e.g., polyester), such as polylactic acid, polylactide, polyglycolide, polycaprolactone, polybutylene adipate terephthalate, polyhydroxyalkanoates, such as polyhydroxybutyrate, as well as copolymers of the monomers that form one or several of the foregoing polymers.

[0045] In one embodiment, the porous material comprises additional components selected from fillers, pigments, sizes, processing aids, and reinforcing materials, and combinations thereof, typically in an amount of 1 to 75%, particularly 2 to 50%, of the total weight of the porous material.

[0046] In one embodiment, the porous material comprises a filler that can impart at least some barrier properties to the porous material. Examples of such fillers include clays, nanoclays, geopolymers, cellulose, nanocellulose, and talc.

[0047] In one embodiment the porous material, in particular the web or sheet or nonwoven material, comprises reinforcing fibres such as carbon or glass fibres or a combination thereof, typically containing 0.1 to 50% by weight, in particular 1 to 20% by weight, of such fibres.

[0048] The porous material may be obtained, for example, by sheet or web formation, for example, by a wet-laying or dry-laying process.

[0049] The porous material can be obtained from a thermoplastic material by a film-forming process such as blow molding or extrusion.

[0050] The powder composition of the present invention can be applied onto a substrate as a single layer or a multi-layer coating. Preferably, it is applied onto a substrate as a single layer coating.

[0051] According to one embodiment, the coating of the present invention is a uniform, preferably odorless and / or flexible film.

[0052] According to one preferred embodiment, the coating layer has a thickness of 10 to 250 μm, more preferably 20 to 150 μm, for example 40 to 80 μm. Such a thickness can be obtained, for example, by using an electrostatic coating method.

[0053] According to one embodiment, the ground biopolymer powder composition has a particle size of 1 to 150 μm, preferably 5 to 150 μm, more preferably 10 to 120 μm, for example 20 to 100 μm, which can be measured by laser diffraction scattering.

[0054] The biodegradable polyester used to form the biopolymer of the powder composition of the present invention can be any biodegradable polyester. It can be a commercial grade biopolyester or can be produced using known polymerization routes. According to a preferred embodiment, the biodegradable polyester is a thermoplastic polyester such as polybutylene succinate, polyglycolic acid, polyhydroalkanoate, e.g., polyhydroxybutyrate or polyhydroxybutyrate-co-hydroxyvalerate, polyaprolactone, polylactide acid, preferably polybutylene succinate, preferably polybutylene succinate.

[0055] More than one polyester can be used in the present invention, for example, two different polyesters can be used to form the biopolymer.

[0056] The siloxane precursor used can be a siloxane monomer, oligomer, or polymer, or any mixture thereof. The siloxane precursor can be an unmodified or non-modified siloxane, such as triethoxysilane, tetraethoxysilane, methyltriethoxysilane, 1,2-bis(triethoxysilane)ethane, 1,2-bis(dimethoxymethylsilane)ethane, 1,2-bis(diethoxymethylsilane)ethane, (3-glycidoxypropyl)trimethoxysilane, phenyltrimethoxysilane, (3-aminopropyl)triethoxysilane, stearyltriethoxysilane, polymethylsilsesquioxane, methacryloxypropyltriethoxysilane, methacryloylpropyltriethoxysilane, polypropyltrimethoxysilane, or perfluorooctyltriethoxysilane. It can be perfluorooctyltriethoxysilane, perfluorooctyltrimethoxysilane, polysilicone-22, polysilicone-27, silanetriol, sorbitylsilanediol, or a mixture of any of these.

[0057] According to one preferred embodiment, the biopolymer of the powder composition is formed by the reaction product of polybutylene succinate and a siloxane oligomer.

[0058] According to one embodiment, the biopolymer formed by the reaction between the polyester and the siloxane precursor is a random polymer containing repeating siloxane units in the hydrocarbyl backbone. According to a further embodiment, the formed biopolymer comprises a polyester grafted with a siloxane precursor. The reaction product of the polyester and the siloxane precursor typically has a number-average molecular weight of 2 to 1,500,000 g / mol, preferably 2,500 to 50,000 g / mol, as measured by gel permeation chromatography (GPC). The molecular weight can be measured as follows: Prior to the GPC measurement, the sample is dissolved overnight in chloroform (concentration 1 to 5 mg / ml) and filtered (0.45 μm). The measurement is carried out in a chloroform eluent (0.6 ml / min, T=30°C) using a high-resolution water column (Styragel HR 4 and 3) with a precolumn. The elution curve was detected using a RI detector (Waters 2414). Molar mass distributions (MMD) were calculated relative to 10× polystyrene (PS) (580-3,040,000 g / mol) standards using chromatography software (Waters Empower 3 software).

[0059] The reaction product, i.e., the biopolymer composition, is ground to form a powder composition preferably containing hydrocarbyl residue and siloxane residue in a molar ratio ranging from 99:1 to 25:75, preferably 95:5 to 60:40.

[0060] According to one embodiment, the powder composition comprises at least 50% by weight, preferably 50-95% by weight, more preferably 85-94% by weight, for example 89% by weight, of polyester, calculated on the total weight of the powder composition.

[0061] According to one embodiment, the molar fraction of the polyester is 10 to 80 mol %, preferably 20 to 60 mol %, for example 30 to 50 mol % of the powder composition.

[0062] According to one embodiment, the powder composition comprises at least 0.1 wt. % siloxane, preferably at least 0.3 wt. % siloxane, for example 0.5-2.0 wt. % siloxane.

[0063] According to one embodiment, the molar fraction of siloxane is 5-90 mol %, preferably 20-80 mol %, for example 40-70 mol % of the powder composition.

[0064] According to a preferred embodiment, the reaction product forming the biopolymer is formed by an esterification reaction between a polyester and a siloxane precursor. According to another preferred embodiment, the powder composition formed is entirely biodegradable.

[0065] Polyols can be used in the formation of biopolymer compositions as plasticizers, to improve leveling, or as catalysts. The polyol can be a monomeric, oligomeric, or polymeric polyol containing two or more hydroxyl groups, such as glycol, glycerin, pentaerythritol, sorbitol, xylitol, polyethylene oxide, polyethylene glycol, trimethylene glycol, or polypropylene glycol, or any mixture thereof. The polyol can be reacted with the siloxane precursor before reacting the siloxane with the polyester. According to another embodiment, the polyol can be added to the reaction mixture of the polyester and the siloxane precursor, or the polyol can already be present in the polymerization reaction of the polyester, and the siloxane precursor can then be added thereto.

[0066] According to one embodiment, the composition also contains other additives that can be used to improve the properties and performance of the prepared powder composition. Additives such as leveling aids or viscosity modifiers, or combinations thereof, can be used, for example, to improve film deposition on substrates. Additives can be added to the ground biopolymer using dry blending, or they can be incorporated into the biopolymer using melt compounding to produce a biopolymer compound with one or more additives. After melt compounding (e.g., by extrusion or kneading), the prepared compound can be ground using, for example, cryogrinding or solvent preparation. The additives used can be, for example, oligomers, plasticizers, oils, or leveling agents, or any mixture thereof. Preferably, the additive is polyether-modified polydimethylsiloxane, polyacrylate, polyethylene glycol, or a combination thereof.

[0067] The composition may also include inorganic and / or organic fillers such as talc, geo, starch, wheat gluten or other natural polysaccharides, or wood derivatives such as cellulose, lignin and their derivatives, or any combination thereof.

[0068] According to one embodiment, the powder composition has a glass transition temperature T g The melting temperature of the composition is about 80°C or higher, preferably 120 to 150°C.

[0069] The present invention also relates to a method of producing a packaging material by applying to a porous substrate a powder composition of the present invention comprising a biopolymer formed by the reaction product of a biodegradable polyester and a siloxane precursor, preferably wherein the powder composition provides barrier properties to the packaging material.

[0070] According to one embodiment, the coating has a hardness of 300 g / (m2) measured at 38° C. and 90% RH. 2 24h), preferably less than 100g / (m 2Provides barrier properties in the form of a water vapor transmission rate (WVTR) of less than 24h.

[0071] The method of the present invention includes the steps of providing a porous substrate, providing a polyester, and providing a siloxane precursor, reacting the polyester with the siloxane precursor to form a biopolymer composition, and grinding the biopolymer composition to form a powder, which is then applied onto the porous substrate and cured to form a packaging material.

[0072] According to one embodiment, the reaction between the polyester and the siloxane precursor occurs in a liquid state. According to one embodiment, the liquid state is formed by the siloxane precursor solution, the polyester, and a solvent. Preferably, the solvent is an organic solvent or a mixture of solvents such as ethanol or ethyl acetate, or a mixture thereof.

[0073] The siloxane precursor can be mixed with the polyester directly or dissolved in a solvent such as ethanol before mixing. In particular, when two or more siloxane precursors are used, a mixture thereof is usually formed before reacting with the polyester. This can be done, for example, by mixing two or more siloxane precursors in a round-bottom flask at room temperature for 0.5 to 2 hours, preferably about 1 hour. Thus, according to one embodiment, the siloxane precursor is obtained by mixing two or more siloxanes at room temperature. The formed siloxane precursor can be a siloxane oligomer or polymer.

[0074] The polyester can be in a liquid state before mixing with the siloxane precursor, or can be in a liquid state while mixing with the siloxane precursor using a solvent in the reaction mixture, preferably an organic solvent or solvent mixture such as ethyl acetate or acetone.

[0075] According to another embodiment, the polyester and siloxane precursors can be mixed using melt compounding, such as twin-screw extrusion, in which the polyester and siloxane precursors are reacted with each other by reactive extrusion in a melt compounding process.

[0076] According to one embodiment, the siloxane precursor is mixed with the polyester in the presence of a solvent and, optionally, a plasticizer, or catalyst, and additives.

[0077] According to another embodiment, a siloxane precursor solution is formed by dissolving one or more siloxane precursors in a solvent prior to mixing with the polyester.

[0078] According to a further embodiment, the siloxane precursor solution is reacted with a plasticizer or catalyst, preferably a polyol, before mixing with the polyester. This can be done, for example, at a temperature of 120-200°C, preferably about 160°C, under a nitrogen atmosphere, using a reflux condenser for about 1-2 hours. After heating, the mixture is cooled to room temperature.

[0079] According to another embodiment, a plasticizer or catalyst can be added to the reaction mixture of the polyester and the siloxane precursor. Thus, according to one embodiment, the polyester and siloxane are reacted in the presence of a plasticizer or catalyst, which is preferably a monomer or polymer polyol containing two or more hydroxyl groups.

[0080] Heating is necessary to obtain a reaction between the polyester and the polysiloxane precursor. According to one embodiment, the polyester and siloxane precursor are reacted at an elevated temperature of at least 60°C, preferably 60-150°C, and more preferably 60-100°C. Typically, mixing is carried out under a nitrogen atmosphere using a reflux condenser for about 15 minutes to 1 hour, preferably about 30 minutes. The polyester and siloxane precursor can also be reacted under air or any protective atmosphere. After the reaction has taken place, the formed biopolymer composition is cooled to room temperature.

[0081] According to one embodiment, any solvents used in the reaction mixture can be removed after the reaction between the polyester and the siloxane has occurred. This is preferably done by solvent evaporation. Thus, according to a preferred embodiment, the powder coating composition is essentially solvent-free, i.e., the composition contains no more than 0.5% by weight, preferably no more than 0.1% by weight, and most preferably 0% by weight of solvent.

[0082] To obtain a powder composition, the biopolymer composition is typically milled, which can be done by any known milling method, such as grinding, impact, milling, or solvent precipitation.

[0083] According to one embodiment, the grinding is carried out by cryogrinding. Liquid nitrogen or liquid carbon dioxide can be used to create the cryogenic conditions for grinding. The biopolymer composition to be ground typically has a glass transition temperature (T) below 100°C. g ), pre-cooling of the polymer granules prior to cryogrinding is preferably carried out, for example by placing the granules in liquid nitrogen before grinding. The cryogenic mill used may be of the impact mill type with an adjustable feed screw that also allows the supply of coolant to the mill. During grinding, the coolant supply is controlled so that the temperature in the mill remains below the glass transition temperature of the ground biopolymer.

[0084] In one embodiment, the particle size of the milled biopolymer composition is between 10 and 120 μm as measured by laser diffraction scattering.

[0085] In another embodiment, milling is performed by solvent precipitation. This can be accomplished by first dissolving the biopolymer in a solvent such as acetone, ethyl acetate, isoamyl alcohol, toluene, or chloroform to form a solution typically containing about 1 to about 50% by weight, and particularly 5 to 40% by weight, of the biopolymer. Dissolution is typically performed at temperatures ranging from 50 to 150°C. Dissolution is typically performed by mixing, preferably using a reflux condenser. After dissolution, precipitation of the biopolymer from the solvent is performed by cooling the suspension to room temperature under continuous stirring. Once the polymer has precipitated, the solvent is removed by solvent evaporation. To obtain a very fine powder, further milling with nitrogen cooling can be used to generate an even finer particle size distribution. Particle sizes of 10 to 120 μm can be achieved, as measured by laser diffraction scattering.

[0086] The powder composition can be applied to a substrate, for example, by using electrostatic spray coating techniques. These include the use of triboelectric spray guns, corona-charged spray guns, electromagnetic brush (EMB) techniques, or fluidized beds, preferably electrostatic spray guns. However, other coating methods are also applicable.

[0087] The electrostatic spray coating method involves projecting electrically charged biopolymer powder particles toward a conductive substrate by electrostatic charging. In the method of the present invention, the distance between the spray gun and the substrate is preferably 10 to 100 cm, preferably 30 to 80 cm, for example, about 50 cm.

[0088] After the powder composition is applied to a substrate, the composition must be cured to form a uniform and homogeneous coating layer. Once exposed to elevated temperatures, the powder composition begins to melt and then preferably chemically reacts to form higher molecular weight polymers in a network structure, e.g., by crosslinking. According to a preferred embodiment, this process, which can also be called "curing," is carried out at elevated temperatures of 100-250°C, preferably about 120-170°C or 180°C, e.g., 150°C. The curing time is typically 1-120 minutes, e.g., 5-20 minutes, preferably about 10 minutes.

[0089] According to one embodiment, the coating according to the invention has an arithmetic mean surface roughness value (Ra) of less than 20 μm, preferably less than 5 μm, measured with an optical profilometer.

[0090] The packaging material according to the invention or produced by the method of the invention may be a packaging material or ready-to-use packaging itself. According to another embodiment, it may be any part of another packaging material or packaging. It may be, for example, a blank, a sheet or an article.

[0091] It is to be understood that the disclosed embodiments of the invention are not limited to the particular structures, processing steps, or materials disclosed herein, but extend to equivalents thereof as recognized by those skilled in the art. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0092] Throughout the specification, reference to an embodiment or embodiments means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. For example, when a numerical value is referenced using terms such as approximately or substantially an exact numerical value, the exact numerical value is also disclosed.

[0093] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list were individually identified as a separate and unique member. Accordingly, individual members of such lists should not be construed as de facto equivalents of any other members of the same list solely based on their presentation in a common grouping, absent indication to the contrary. Furthermore, various embodiments and examples of the present invention may be referenced herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives should not be construed as de facto equivalents of each other, but should be considered as separate and autonomous representations of the present invention.

[0094] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In this description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. However, one skilled in the art will recognize that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc.

[0095] While the above examples illustrate the principles of the present invention in one or more particular applications, it will be apparent to those skilled in the art that numerous modifications in embodiment, use, and detail can be made without departing from the principles and concepts of the present invention and without the capacity of the present invention. Accordingly, the present invention is not intended to be limited except as by the claims set forth below.

[0096] In particular, although this application specifically describes biopolymers formed by the reaction product of biodegradable polyesters and siloxane precursors, it should be understood that other metalloxane precursors may be used in place of or in combination with the siloxanes.

[0097] According to one embodiment, the metalloxane precursor can be selected from the group of siloxane, germanoxane, aluminoxane, titanoxane, zirconoxane, ferroxane, and stannoxane precursors, and combinations thereof. In particular, the metalloxane precursor can be selected from the group of metalloxane monomers, oligomers, and polymers, and combinations thereof, such as siloxane monomers, oligomers, and polymers, and combinations thereof.

[0098] The following non-limiting examples are intended merely to illustrate the advantages obtained with embodiments of the present invention. [Example]

[0099] Example 1 Mixture 1 - Preparation of Siloxane Precursor Solution 25 g (0.1058 mol) of 1,2-bis(triethoxysilyl)ethane, 25 g (0.0705 mol) of (3-glycidoxypropyl)trimethoxysilane, 50 g of ethanol, and 5 g of water were mixed in a round-bottom flask equipped with a magnetic stirrer. The solution was stirred for 1 hour at room temperature.

[0100] Preparation of Biopolymer Powder Compositions 23.4 g of commercial grade polybutylene succinate, 2.6 g of 400 g / mol (M n ), 2.6 g of Mixture 1 (Example 1), and 0.26 g of BYK333 (polyether-modified polydimethylsiloxane) as an additive, and 75 g of technical-grade ethyl acetate were weighed into a 500 ml round-bottom flask. The mixture was heated to 78°C with mixing for 30 minutes using a reflux condenser and under a nitrogen atmosphere. The formed biopolymer suspension was then cooled to room temperature, and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size between 30 and 70 μm.

[0101] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 150 ° C for 10 minutes to form an even coating layer on the substrate.

[0102] Example 2 Mixture 1 - Preparation of Siloxane Precursor Solution 50 g (0.141 mol) of 1,2-bis(triethoxysilyl)ethane, 100 g of ethanol, and 5 g of water were mixed in a round-bottom flask equipped with a magnetic stirrer. The solution was stirred at room temperature for 1 hour.

[0103] (Mixture 2 - Reacting the Siloxane Precursor and Polyol) 60g (0.150mol) of 400g / mol (M n Polyethylene glycol having an average molecular weight of 17.7 g (0.150 mol), 17.7 g (0.150 mol) of biosuccinic acid, and 23.31 g of Mixture 1 (Example 2) were weighed into a 500 ml round-bottom flask. The mixture was heated to 160° C. with mixing using a reflux condenser and under a nitrogen atmosphere for 1 hour and 45 minutes. The mixture was then cooled to room temperature.

[0104] Preparation of Biopolymer Powder Compositions 17.3 g of commercial-grade polybutylene succinate and 2.7 grams of additive Mixture 2 (Example 2) and 50 g of technical-grade ethyl acetate were weighed into a 500 ml round-bottom flask. The mixture was heated to 78°C with mixing for 30 minutes using a reflux condenser and under a nitrogen atmosphere. The formed biopolymer suspension was then cooled to room temperature, and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size between 30 and 70 μm.

[0105] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 150 ° C for 10 minutes to form an even coating layer on the substrate.

[0106] Example 3 Preparation of Biopolymer Powder Compositions 18 g of commercial-grade polybutylene succinate and 0.16 g of BYK333 (polyether-modified polydimethylsiloxane) as an additive and 50 g of technical-grade ethyl acetate were weighed into a 500 ml round-bottom flask. The mixture was heated to 78°C with mixing for 30 minutes using a reflux condenser and under a nitrogen atmosphere. The biopolymer suspension was then cooled to room temperature and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder composition was sieved to a median particle size of between 30 and 70 μm.

[0107] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. It was heated in an air convection oven at 150 ° C for 10 minutes to form an even coating layer on the substrate. It was heated in an air convection oven at 150 ° C for 10 minutes to form an even coating layer on the substrate.

[0108] Example 4 Preparation of Biopolymer Powder Compositions 18 g of commercial grade polybutylene succinate, 2 g of 400 g / mol (M nPolyethylene glycol having an average molecular weight of 0.2 grams and 0.2 grams of BYK333 (polyether-modified polydimethylsiloxane) as an additive and 50 g of technical-grade ethyl acetate were weighed into a 500 ml round-bottom flask. The mixture was heated to 78°C with mixing for 30 minutes using a reflux condenser and under a nitrogen atmosphere. The biopolymer suspension was then cooled to room temperature and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size between 30 and 70 μm.

[0109] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 150 ° C for 10 minutes to form an even coating layer on the substrate.

[0110] Example 5 (polyester synthesis) Poly(butylene succinate) was synthesized using 1,4-butanediol (BDO) and succinic acid (SA) in a 1.1:1 molar ratio. First, esterification of SA and BDO was carried out at temperatures of 160-190°C under a nitrogen atmosphere while removing water and / or methanol from the reaction mixture. When water / methanol could no longer be removed using atmospheric pressure, the polycondensation reaction was initiated in the presence of an organometallic catalyst, i.e., stannous octoate, at temperatures of 200-240°C under vacuum for 4-6 hours. After the desired viscosity of the polymer was achieved, it was recovered from the reaction vessel and pelletized.

[0111] Preparation of Biopolymer Powder Compositions 18 g of the prepared polybutylene succinate, 0.16 g of BYK333 (polyether-modified polydimethylsiloxane) as an additive, and 50 g of technical-grade ethyl acetate were weighed into a 500 ml round-bottom flask. The mixture was heated to 78°C using a reflux condenser and under a nitrogen atmosphere for 30 minutes with mixing. The biopolymer suspension was then cooled to room temperature, and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size of between 30 and 70 μm.

[0112] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 150 ° C for 10 minutes to form an even coating layer on the substrate.

[0113] Example 6 The barrier properties of the compositions shown in the above examples were investigated by overnight liquid absorption tests and the results were compared with an uncoated substrate. The substrate used in the test was cardboard. Oil, ethanol, and water were used as absorbents. The results are shown in Table 1.

[0114] [Table 1]

[0115] Example 7 (Preparation of PLA) L-lactic acid (1000 g, 11.10 mol) was weighed into a round-bottom flask and stirred at 175°C for 4 hours. Next, 0.1 wt% of solid indium tin catalyst was added, and the temperature was raised to 230°C. The formed L-lactide was separated from the mixture by applying a vacuum of 5 mbar. The prepared L-lactide was heated in a round-bottom flask on an oil bath at 170°C. Then, 0.1 wt% of octoate tin catalyst was added, and the reaction was continued for 15 minutes to 4 hours until a molecular weight of 180,000 g / mol was reached.

[0116] Preparation of Biopolymer Powder Compositions 900 g of pre-prepared polylactic acid (PLA) was extruded at an extrusion temperature of 180°C and a screw speed of 150 rpm to obtain 100 g of polylactic acid with an average molecular weight of 400 g / mol (M n The mixture was melt compounded using a twin-screw extruder with 10 g of polyethylene glycol and 10 g of BYK 333. The compounded material was extruded into strands and pelletized into granules.

[0117] (Powder preparation) Biopolymer powder was produced using cryogenic grinding. Prior to grinding, the compounded biopolymer granules were first pre-cooled using liquid nitrogen. The pre-cooled biopolymer granules were then ground into powder using an impact cryogenic mill. Liquid nitrogen was used as the cooling medium in the cryogenic grinding and was continuously supplied to maintain the temperature inside the mill below 0°C. The rotation speed used for grinding was 15,000 rpm, and the material feeding screw speed was 20 rpm. A 90 μm screen plate was used to obtain a finely ground powder for powder coating. The resulting biopolymer powder was dried in a vacuum oven and then used as a coating material.

[0118] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 180°C for 10 minutes to form an even coating layer on the substrate.

[0119] Example 8 Preparation of Biopolymer Powder Compositions 23 g of commercial grade poly(lactic acid), 2.6 g of 900-1100 g / mol (M n ), 2.6 g of Mixture 1 (Example 1), and 0.26 g of BYK359 as an additive, and 100 g of technical grade acetone were weighed into a 500 ml round-bottom flask. The mixture was heated to 55°C with mixing for 60 minutes using a reflux condenser and under a nitrogen atmosphere. The formed biopolymer suspension was then cooled to room temperature and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size of between 30 and 70 μm.

[0120] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 180°C for 10 minutes to form an even coating layer on the substrate.

[0121] Example 9 Preparation of Biopolymer Powder Compositions 45 g of commercial-grade polybutylene succinate, 5.0 g of trimethylene glycol having an average molecular weight between 900-1100 g / mol (Mn), 0.5 g of BYK333 (polyether-modified polydimethylsiloxane) as an additive, and 100 g of technical-grade ethyl acetate were weighed into a 500 ml round-bottom flask. The mixture was heated to 78°C with mixing for 30 minutes using a reflux condenser and under a nitrogen atmosphere. The biopolymer suspension was then cooled to room temperature, and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder composition was sieved to a particle size of less than 100 μm.

[0122] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. It was heated in an air convection oven at 150 ° C for 10 minutes to form an even coating layer on the substrate. It was heated in an air convection oven at 150 ° C for 10 minutes to form an even coating layer on the substrate.

[0123] Example 10 Mixture 1 - Preparation of Siloxane Precursor Solution 50 g (0.201 mol) of methacryloxypropyltrimethoxysilane, 100 g of isopropanol, and 2.1 g of 0.1 M acetic acid were mixed in a round-bottom flask equipped with a magnetic stirrer. The solution was mixed at room temperature for 1 hour.

[0124] (Mixture 2 - Reacting siloxane precursor with polyol) 60g (0.150mol) of 400g / mol (M n Polyethylene glycol having an average molecular weight of 17.7 g (0.150 mol), 17.7 g (0.150 mol) biosuccinic acid, and 23.31 g of Mixture 1 (Example 10) were weighed into a 500 ml round-bottom flask. The mixture was heated to 160° C. with mixing using a reflux condenser and under a nitrogen atmosphere for 1 hour and 45 minutes. The mixture was then cooled to room temperature.

[0125] Preparation of Biopolymer Powder Compositions 17.3 g of commercial-grade polybutylene succinate and 2.7 grams of additive Mixture 2 (Example 10) and 50 g of technical-grade ethyl acetate were weighed into a 500 ml round-bottom flask. The mixture was heated to 78°C with mixing for 30 minutes using a reflux condenser and under a nitrogen atmosphere. The formed biopolymer suspension was then cooled to room temperature, and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size between 30 and 70 μm.

[0126] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 150 ° C for 10 minutes to form an even coating layer on the substrate.

[0127] Example 11 (Preparation of PLA) L-lactic acid (1000 g, 11.10 mol) was weighed into a round-bottom flask and stirred at 175°C for 4 hours. Next, 0.1 wt% of solid indium tin catalyst was added, and the temperature was raised to 230°C. The formed L-lactide was separated from the mixture by applying a vacuum of 5 mbar. The prepared L-lactide was heated in a round-bottom flask on an oil bath at 170°C. Then, 0.1 wt% of octoate tin catalyst was added, and the reaction was continued for 15 minutes to 4 hours until a molecular weight of 180,000 g / mol was reached.

[0128] Preparation of Biopolymer Powder Compositions 900 g of pre-prepared polylactic acid (PLA) was extruded at an extrusion temperature of 180°C and a screw speed of 150 rpm to obtain a polymer with an average molecular weight of 400 g / mol (M nThe mixture was melt compounded using a twin-screw extruder with 100 g of polyethylene glycol (20%) and 10 g of BYK332. The compounded material was extruded into strands and pelletized into granules.

[0129] (Powder preparation) Biopolymer powder was produced using cryogenic grinding. Prior to grinding, the compounded biopolymer granules were first pre-cooled using liquid nitrogen. The pre-cooled biopolymer granules were then ground into powder using an impact cryogenic mill. Liquid nitrogen was used as the cooling medium in the cryogenic grinding and was continuously supplied to maintain the temperature inside the mill below 0°C. The rotation speed used for grinding was 15,000 rpm, and the material feeding screw speed was 20 rpm. A 90 μm screen plate was used to obtain a finely ground powder for powder coating. The resulting biopolymer powder was dried in a vacuum oven and then used as a coating material.

[0130] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 200°C for 10 minutes to form an even coating layer on the substrate.

[0131] Example 12 Preparation of Biopolymer Powder Compositions 980 g of commercial grade polybutylene succinate, 980 g of commercial grade poly(3-hydroxybutyrate-co-3-hydroxyvalerate), 20 g of Mixture 1 (Example 1) and 20 g of BYK360P (polyacrylate) were mixed and melt compounded into granules in a twin-screw extruder at 170° C. using a screw speed of 100 rpm.

[0132] (Powder preparation) Biopolymer powder was produced using cryogenic grinding. Prior to grinding, the compounded biopolymer granules were first pre-cooled using liquid nitrogen. The pre-cooled biopolymer granules were then ground into powder using an impact cryogenic mill. Liquid nitrogen was used as the cooling medium in the cryogenic grinding and was continuously supplied to maintain the temperature inside the mill below 0°C. The rotation speed used for grinding was 15,000 rpm, and the material feeding screw speed was 20 rpm. A 90 μm screen plate was used to obtain a finely ground powder for powder coating. The resulting biopolymer powder was dried in a vacuum oven and then used as a coating material.

[0133] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 170 ° C for 10 minutes to form an even coating layer on the substrate.

[0134] Example 13 Preparation of Biopolymer Powder Compositions 15 g of commercial-grade polylactic acid, 32 g of commercial-grade terephthalate succinate, 2.5 g of polyethylene glycol with an average molecular weight of 200 g / mol (Mn), 0.5 g of commercially available polyether-modified polydimethylsiloxane (BYK332), and 50 g of industrial-grade acetone were weighed into a 500 ml round-bottom flask. The mixture was heated to 55 °C using a reflux condenser and mixed for 30 minutes under a nitrogen atmosphere. The formed biopolymer suspension was then cooled to room temperature, and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size of 30-70 μm.

[0135] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 180°C for 10 minutes to form an even coating layer on the substrate.

[0136] Example 14 (Talc surface modification) 30 g of talc powder (median particle size 1 μm) was mixed with 200 g of ethanol and 10 g of 3-aminopropyltriethoxysilane with magnetic stirring at room temperature for 3 hours. The talc was filtered from the solution, washed with 200 ml of ethanol and 500 ml of deionized water, and then dried overnight at 60°C in an air convection oven.

[0137] Preparation of Biopolymer Powder Compositions 490 g of commercial-grade polylactic acid, 480 g of commercial-grade terephthalate succinate, 20 g of surface-modified talc, and 10 g of commercially available polyether-modified polydimethylsiloxane (BYK307) were melt-compounded in a twin-screw extruder at 190 °C using a screw speed of 100 rpm. 25 grams of the melt-compounded biopolymer composition and 100 g of technical acetone were then weighed into a 500 ml round-bottom flask, heated to 55 °C using a reflux condenser, and mixed for 30 minutes under a nitrogen atmosphere. The formed biopolymer suspension was then cooled to room temperature, and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size between 30 and 70 μm.

[0138] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 180°C for 10 minutes to form an even coating layer on the substrate.

[0139] Example 15 Mixture 1 - Preparation of Siloxane Precursor Solution 22.3 g of an aqueous biosuccinic acid solution (1.3 wt % biosuccinic acid diluted with deionized water) was slowly added to 191.7 g of methyltriethoxysilane. The solution was mixed at room temperature for 12 hours before use.

[0140] Preparation of Biopolymer Powder Compositions 470 g of commercial-grade polybutylene succinate, 25 g of polyethylene glycol with an average molecular weight of 200 g / mol (Mn), and 5 g of Mixture 1 (Example 15) were melt-blended using a twin-screw extruder at 140°C with a screw speed of 100 rpm. 50 g of the blended biopolymer composition and 100 g of technical-grade ethyl acetate were weighed into a 500 ml round-bottom flask. The mixture was heated to 78°C with mixing for 30 minutes using a reflux condenser and under a nitrogen atmosphere. The formed biopolymer suspension was then cooled to room temperature, and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size between 30 and 70 μm.

[0141] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 160°C for 10 minutes to form an even coating layer on the substrate.

[0142] Example 16 Mixture 1 - Preparation of Siloxane Precursor Solution 40 g (0.29 mol) of methyltrimethoxysilane, 80 g of ethanol, and 5 g of water were mixed in a round-bottom flask equipped with a magnetic stirrer. The solution was stirred for 1 hour at room temperature.

[0143] Preparation of Biopolymer Powder Compositions 23 g of commercial grade polylactic acid, 2.6 g of 900-1100 g / mol (M n Trimethylene glycol having an average molecular weight between 100 and 200 μm, 2.6 g of Mixture 1 (Example 16), and 100 g of technical grade acetone were weighed into a 500 ml round-bottom flask. The mixture was heated to 55° C. with mixing for 90 minutes using a reflux condenser and under a nitrogen atmosphere. The formed biopolymer suspension was then cooled to room temperature and the solvent was removed using solvent evaporation. After solvent removal, the resulting powder was sieved to a median particle size between 30 and 70 μm.

[0144] (substrate coating) The powder composition was used for powder coating of cardboard substrates using electrostatic charging. The coating was applied to the charged substrate using an electrostatic spray gun at a distance of 50 cm. The substrate coated with the powder composition was then heated in an air convection oven at 180°C for 10 minutes to form an even coating layer on the substrate.

[0145] Example 17 The barrier properties of the compositions shown in the above examples were investigated by overnight liquid absorption tests, and the results were compared to uncoated substrates and PBS and PLA powders. Standards were powdered using the solvent method described in the previous examples. The PBS reference was prepared using ethyl acetate, a temperature of 78°C, and a reflux condenser, and the PLA reference was prepared using acetone, a temperature of 55°C, and a reflux condenser. The biopolymer suspensions were cooled to room temperature and powdered by removing the solvent by evaporation.

[0146] The substrate used in the test was cardboard. Oil, ethanol (50% ethanol:water mixture), and water containing blue dye were used as absorbents. The measurement results are shown in Table 1.

[0147] [Table 2]

[0148] The results in Table 1 show that the powder coating compositions according to the present invention have better coating quality and barrier properties compared to uncoated substrates and the reference PBS and PLA materials. The improved barrier properties of the powder coatings may be related to the combination of biopolyester and siloxane precursor in the material composition according to the present invention. Also, the smoothness and smoothness of the coatings according to the present invention were clearly improved compared to the standards.

[0149] The powder coating compositions according to the present invention also have better oil resistance compared to uncoated substrates and the reference PBS and PLA materials, the latter of which have poorer oil resistance due to the poorer coating quality of the materials.

[0150] The ethanol and water resistance of the coating composition according to the invention was also significantly improved compared to the uncoated substrate: there was no sign of ethanol or water absorption in the substrate. [Industrial Applicability]

[0151] The present invention can be used to produce packaging materials having a biopolymer coating, and generally to replace conventional methods of producing packaging materials.

[0152] The powder coating compositions of the present invention are particularly useful for packaging materials for food, cosmetics, and pharmaceuticals. In particular, the present invention allows for single layer coatings on porous substrates.

Claims

1. A packaging material comprising a coated porous substrate, characterized in that the porous substrate is coated with a molten layer comprising a biopolymer formed by the reaction product of a biodegradable polyester and a metalloxane precursor.

2. The packaging material of claim 1 , wherein the substrate comprises a single layer coating.

3. 3. The packaging material of claim 1 or 2, wherein the coating provides barrier properties for the packaging material.

4. 4. Packaging material according to claims 1 to 3, wherein the coating has an arithmetic mean surface roughness value (Ra) below 20 μm as measured by an optical profilometer.

5. The packaging material according to any one of claims 1 to 4, wherein the metalloxane precursor is a siloxane precursor selected from the group consisting of siloxane monomers, oligomers, and polymers, and combinations thereof, and the biodegradable polyester is a polyhydroalkanoate selected from the group consisting of polybutylene succinate, thermoplastic biopolymers selected from the group consisting of polyglycolic acid, polyhydroxybutyric acid or polyhydroxybutyric acid valerate or polyhydroxybutyric acid-co-hydroxyvalerate, polycaprolactone, polylactic acid, and polybutylene adipate terephthalate.

6. A packaging material described in any of claims 1 to 5, wherein the metalloxane precursor is a siloxane precursor, and the siloxane precursor is reacted with a monomeric or polymeric polyol containing two or more hydroxyl groups selected from the group consisting of glycol, glycerol, pentaerythritol, sorbitol, xylitol, polyethylene oxide, polyethylene glycol, trimethylene glycol, or polypropylene glycol before being mixed with the polyester.

7. The packaging material of any one of claims 1 to 6, wherein the formed biopolymer is a random polymer containing repeating siloxane units in a hydrocarbyl backbone.

8. A packaging material described in any one of claims 1 to 7, wherein the metalloxane precursor is a siloxane precursor, the reaction product forming the biopolymer is formed by an esterification reaction between the polyester and the siloxane precursor, and the reaction product has a number average molecular weight of 2,000 to 1,500,000 g / mol.

9. The packaging material according to any one of claims 1 to 7, wherein the coating is obtained by melting a powder coating composition applied onto the surface of the porous substrate.

10. 10. The packaging material of claim 9, wherein the powder composition has an average particle size of 5 to 150 μm.

11. 11. The packaging material according to claim 9 or 10, wherein the powder composition comprises at least 50 wt.-% of the polyester, and the powder composition contains hydrocarbyl residues and siloxane residues in a molar ratio ranging from 99:1 to 50:

50.

12. The powder composition has a glass transition temperature, T ｇ The packaging material according to any one of claims 9 to 11, having a melting point of 80°C or higher.

13. 13. The packaging material according to any one of claims 9 to 12, wherein the powder composition further comprises inorganic and / or organic fillers selected from the group of talc, geo, starch, wheat gluten or other natural polysaccharides, or wood derivatives selected from the group of cellulose, lignin and derivatives thereof, or any combination thereof.

14. Packaging material according to any of the preceding claims, wherein the substrate is gas and / or liquid permeable and is selected from the group consisting of paper, cardboard or plastic.

15. A method for producing a packaging material by coating a porous substrate, comprising the steps of: - providing a porous substrate; - providing a polyester; - providing a siloxane precursor; - reacting said polyester with a metalloxane precursor to form a biopolymer composition; - grinding the biopolymer composition to form a powder; - applying said powder onto said porous substrate; and - curing the applied powder to form a packaging material; Including, the biopolymer composition comprises a biopolymer formed by the reaction product of a biodegradable polyester and a metalloxane precursor; method.

16. - the siloxane precursor is obtained by mixing two or more siloxanes at room temperature, and - the solvent is removed from the biopolymer composition prior to grinding, and / or - the polyester and the siloxane precursor are reacted at an elevated temperature of at least 60°C under nitrogen, air or any protective atmosphere; 16. The method of claim 15.

17. 17. The method of claim 15 or 16, wherein the polyester and the siloxane precursor are reacted in the presence of a monomeric, oligomeric, or polymeric polyol containing two or more hydroxyl groups.

18. the biopolymer composition is pulverized to form a powder having an average particle size of 1 to 150 μm, and the pulverization is performed by grinding or solvent precipitation; and The method according to any of claims 15 to 17, wherein the powder is applied by using electrostatic spray coating, after which the curing is carried out.

19. The method of any of claims 15 to 18, wherein the polyester and the siloxane precursor are mixed using melt compounding.

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