Protein blend material with zein and a second plant protein, and a method for producing a film or an absorbent foam from the material

Abstract

The present invention relates to the field of absorbent articles constructed with materials comprising proteins, thereby providing alternatives to conventional petroleum based absorbent articles. A material comprising a first protein, a second protein and a plasticizer is presented, wherein the first protein is zein, and the second protein is selected from a group consisting of glutenin, gliadin, secalin, hordein, avenin or a combination thereof. Additionally, methods for producing a film, a porous film and a foam of the material and an absorbent article comprising the material are presented.

Description

[0001] PROTEIN BLEND MATERIAL, METHOD OF PRODUCING A PROTEIN BLEND MATERIAL AND ABSORBENT ARTICLE COMPRISING PROTEIN BLEND MATERIAL FIELD OF THE INVENTION The present invention relates to the field of absorbent articles constructed with materials comprising proteins, thereby providing alternatives to conventional petroleum based absorbent articles. BACKGROUND OF THE INVENTION A wide range of personal hygiene products use absorbent and porous materials to absorb, distribute and retain large amounts of water, blood or other body fluids. Disposable absorbent articles, such as diapers, incontinence pads, sanitary pads, breastfeeding pads, band aids, absorbent protection bedsheets and the like require not only a high absorption capacity but also a high absorption under load. Conventionally diapers, incontinence pads and sanitary pads use absorbent and porous materials that are petroleum based and constructed from so called superabsorbent polymers, such as based on poly(acrylic acid), and non-woven fibers, such as polyethylene and polypropylene. Furthermore, diapers, incontinence, and sanitary pads are consumables intended as single-use products and must be disposed of after respective liquid uptake. However, the conventional materials employed are not biodegradable and their disposal contributes to municipal solid waste as well as the risk of accumulation of microplastics in nature. Due to the dependency on petroleum feedstocks, the short product life and the liability of their disposal, there is a demand to develop biodegradable new materials for absorbent articles from biomass feedstocks. Furthermore, conventional diapers, incontinence pads and sanitary pads are assembled with petroleum based films and porous films encapsulating the absorbent material, which further contributes to problems with disposal and accumulation of microplastics. Naturally sourced polymeric materials, such as proteins, have been considered for use in foams and films for absorbent articles. Wheat gluten constitutes a source of material that is obtained as a co-product from wheat starch extraction and bioethanol production. A problem with the adoption of wheat gluten is that it requires addition of toxic cross- linkers such as glutaraldehyde and plasticizers to stabilize the materials, prevent phase separation of mixtures, and prevent the collapse of the material accompanied with drying. Additionally, wheat gluten has a risk of cross-linking to itself in processes that are difficult to control as well as resulting in materials difficult to process into homogeneous porous structures. Generally, wheat gluten is also rapidly attacked by microorganisms, such as mold, thereby limiting the shelf life of gluten based materials. Alternatively, wheat gluten requires processing prior to material production, such as acylation. However, these additional processes influence the cost of the materials. For novel materials to compete with conventional alternatives, it is necessary to develop compositions and cost efficient manufacturing conditions that produce biodegradable materials with homogeneous structures and a high capacity of absorbing liquids while exhibiting a shelf life comparable to conventional alternatives. SUMMARY OF THE INVENTION The objective of the present invention is to overcome the drawback of the prior art and to present a material based on protein blends. The present inventors found that a material comprising a plasticizer, a first protein, wherein the first protein is zein, and a second protein, wherein the second protein is selected from a group consisting of glutenin, gliadin, secalin, hordein, avenin or a combination thereof, resulted in a material that demonstrated an ability to form porous extrudates, porous films or films from the same formulation. In a first aspect the present invention relates to a material comprising i) A first protein, wherein the first protein is zein, ii) A second protein selected from a group consisting of glutenin, gliadin, secalin, hordein, avenin or a combination thereof, and iii) A plasticizer, wherein the material has a weight ratio between zein and the second protein between 1:1 and 4:1, preferably between 1:1 and 3:1. In a second aspect the present invention relates to a method for producing a film, a porous film or a foam, wherein the method comprises a. Providing zein b. Providing a second protein, wherein the second protein is selected from a group consisting of glutenin, gliadin, secalin, hordein, avenin or a combination thereof, c. Providing a plasticizer, wherein the plasticizer is selected from a group consisting of glycerol, water, sorbitol, propylene glycol, diethanolamine, and triethanolamine or a combination thereof, and d. Optionally providing a crosslinking agent selected from a group consisting of genipin, genipin oil, aglycone, dialdehydes, polycarboxylic acids, phenolic compounds, epoxy compounds or a combination thereof, e. Optionally providing a filler wherein the filler is preferably one or more potato proteins, wheat bran, cereal husks, cereal straws or a combination thereof, wherein the filler is more preferably patatin, and wherein the film is produced by performing steps A1 and A2 A1. Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent and optionally the filler to form a mixture, wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1, and A2. Extruding the mixture to a film wherein the porous film or foam is produced either by performing steps B1, B2 and B3 B1. Providing a foaming agent, wherein the foaming agent is selected from a group consisting of bicarbonate and water or a combination thereof, preferably sodium bicarbonate, and B2. Mixing the zein, the second protein, the plasticizer, optionally the crosslinking agent, optionally the filler and the foaming agent to form a mixture, wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1, and B3. Extruding the mixture to a porous film or a foam the porous film or foam is produced by performing steps C1 and C1. Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent and optionally the filler to form a mixture, wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1, and C2. Extruding the mixture, wherein gas is injected to the mixture in the extruder, to a foam or a porous film. In a third aspect the present invention relates to an absorbent article comprising a film, an absorbent member comprising the foam according to the first aspect of the invention, and a porous film. All embodiments disclosed herein may be combined and relates to all aspects of the present invention unless stated otherwise. BRIEF DESCRIPTION OF FIGURES Figure 1 illustrates an embodiment of the method according to an aspect of the technology proposed herein. Figure 2 shows photographs of extruded foams according to example 1, prior to and after immersion in water for 24 hours. Figure 3 illustrates water swelling results for extruded foams according to example 1. Figure 4 illustrates free swelling capacities in saline solution for foam samples according to example 1. Figure 5 illustrates centrifuge retention capacities in saline solution for samples according to example 1. Figure 6 shows a photograph of absorbent articles assembled according to example 2. Figure 7 shows a foam sample molded according to example 3. Figure 8 illustrates visual absorption test in defibrinated sheep blood of samples according to example 3. Figure 9 shows photographs of samples according to example 5. Figure 10 illustrates weight loss results of samples according to example 6. Figure 11 illustrates photographs of samples according to example 7. Figure 12 illustrates a photograph of a sample according to example 8. DEFINITIONS Genipin oil: The oil is the product of the extraction of oleic substances (such as genipin) contained in the fruit of the Rubiaceae trees family such as Genipa Americana. The oil is a liquid dispersion containing natural non-toxic crosslinkers such as at least 10% of genipin. Water swelling capacity: Determined by completely immersing samples of 1 cm long pieces of the foam in water for 24 hours. After removing the samples from the liquid, excess liquid was removed by placing the samples on tissue paper for 10 seconds. Water swelling capacity was calculated according to ^^− (^^− ^^ ^) ^^^^^ ^^^^^^^^ ^^^^^^^^ = (^^− ^^^) for which W2 denotes the swollen weight of the sample, W1 denotes the dry weight of the sample, W’1 denotes the dry weight of the sample after swelling. Centrifuge retention capacity: A measure of the fluid retention of samples, determined by swelling samples in 0.9 weight-% NaCl aqueous solution for 30 min, followed by centrifugation of samples kept inside bags for 3 minutes at 1250 rpm. Centrifuge retention capacity (CRC) is calculated according to the equation below ^^ where Wc denotes the weight of the centrifuged sample in the bag, W0 denotes the weight of the dry bag used, Wddenotes the weight of the sample, and Wbdenotes the correction factor. In turn, the correction factor is calculated according to ^^where WSdenotes the weight of the W is the weight of the dry bag.

[0002] DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, the material comprises a first protein wherein the first protein is zein and a second protein, wherein the material has a weight ratio between zein and the second protein between 1:1 and 4:1, preferably between 1:1 and 3:1. The second protein is selected from a group consisting of glutenin, gliadin, secalin, hordein, avenin or a combination thereof. Additionally, the material comprises a plasticizer. The zein can be obtained as a by-product from the industrial starch extraction from corn or as a by-product from the industrial corn fiber extraction. The second protein can for example be obtained as a by-product from the industrial starch extraction from wheat, barley, rye, oat. These by-products may not, due to residues of other non-protein compounds, be used in food applications without further treatment. The present invention, however, found that these by-products can serve as feedstocks to produce a cheap material according to the present invention. Accordingly, the technology proposed herein is based on the realization that a material comprising a plasticizer as well as zein and a second protein, in a weight ratio as specified above, yields a material with the ability to form continuous porous extrudates, porous films and films from the same composition, without the addition of toxic crosslinking agents such as glutaraldehyde. In one embodiment, the sum of zein and the second protein is at least 50 weight-% with respect to the total weight of the material, preferably 60 weight-%. An increased content of zein and the second protein is accompanied with an increased water swelling capacity for foams of the material, as well as increase the rate of biodegradation. Additionally, zein increase the shelf life of the material as it results in a material that is less susceptible to growth of mold. In one embodiment, the material comprises 20-40 weight-% plasticizer. The plasticizer is selected from the group consisting of glycerol, water, sorbitol, propylene glycol, diethanolamine, and triethanolamine or a combination thereof. The amount of plasticizer affects the mechanical properties of the material as well as the porosity of the material when extruded into a film, foam or a porous film. However, the plasticizers are soluble in water, and may dissolve during absorption use thus jeopardizing the integrity of the material. In a preferred embodiment the amount of plasticizer is between 25-35 weight-%. Additionally, the material is at least partly biodegradable, preferably wherein at least 50 weight-% of the material is biodegradable within 2 weeks in soil comprising farmland and compost at a weight ratio of 2:1, at room temperature and 70-80% relative humidity. The material may also be at least partly cross-linked, to further improve the strength of the material. Crosslinking may be obtained by inclusion of crosslinking agents. In one embodiment, the material comprises 0.05 – 5 weight-% crosslinking agent, preferably 0.5-1.5 weight-%. Preferably wherein the crosslinking agent is selected from genipin, genipin oil, aglycone, dialdehydes, polycarboxylic acids, phenolic compounds, epoxy compounds, or a combination thereof. The addition of crosslinking agent increases the mechanical stability of the material, and for a foam of the material it prevents pores from collapsing as well as promotes formation of uniform and spherical pores. Moreover, the addition of crosslinking agent delays hydrolysis of the proteins in humid conditions, thereby increasing the stability of the material. Genipin is aglycones derived from an iridoid glycoside or geniposide. Genipin oil is the product of the extraction of oelic substances contained in the fruit of the Rubiaceae trees family, such as from Genipa Americana. Genipin oil is a liquid dispersion containing genipin. Genipin and genipin oil are natural and non-toxic crosslinking agents. Furthermore, the addition of genipin or genipin oil results in a black material, which is a preferred color for materials used in black sanitary products, such as sanitary pads. In a preferred embodiment, the crosslinking agent is genipin oil. Genipin oil promotes the expansion of the material in the form of a foam. Genipin oil comprises genipin as well as lipids and phenolic compounds, without being bound by theory these lipids and phenolic compounds are believed to be involved in the formation of bonds between the prolamin groups in the proteins thereby promoting the expansion of the material, and the lipids may additionally act as lubricant during material processing such as extrusion. Additionally, genipin oil can be a significantly cheaper alternative to genipin, since genipin requires additional purification steps after extraction. In one embodiment, the material comprises 5-15 weight-% filler, wherein the filler is preferably one or more potato proteins, wheat bran, cereal husks, cereal straws or a combination thereof wherein the filler is more preferably patatin. The filler is preferably potato proteins. Higher content of potato proteins results in increased rate of biodegradation. However, when the material comprises a crosslinking agent the potato proteins are also involved in crosslinking and thereby contributes to the mechanical properties and porosity of the material. For foam materials comprising 5- 15 weight-% potato proteins, the addition of 0.05-5 weight-% crosslinking agent results in higher water swelling capacities. For foam materials comprising potato proteins above 15 weight-%, the addition of 0.05-5 weight-% crosslinking agent results in lower water swelling capacities. In one embodiment of the invention, the material is in the form of a foam, film or a porous film. The protein which constitutes the major portion of the proteins in the material is referred to as the dominant matrix, and the other proteins which constitute minor portions of the proteins in the material are referred to as proteins in the dispersed phase. When the material is in the form of a foam or a porous film, the porosity is favoured when the zein is the dominant matrix and the second protein is in the dispersed phase. A foam of the present invention is a material with a porous structure capable of absorbing at least 6 g of saline solution (0.9 weight-% NaCl in water) per gram of the material after 10 minutes and has a centrifuge retention capacity of at least 2 g of said saline solution per gram of material after centrifugation at 1250 rpm for 3 minutes. The absorption capacity for blood, as tested using defibrinated sheep blood by Visual Absorption Test, is at least 4 g of blood per gram of material. According to another aspect, the present invention relates to a method of producing a film, a porous film or a foam. The second protein in the method, is a protein selected from a group consisting of glutenin, gliadin, secalin, hordein, avenin or a combination thereof. The plasticizer is preferably selected from glycerol, water, sorbitol, propylene glycol, diethanolamine, triethanolamine or a combination thereof. The optional crosslinking agent in the method is selected from a group consisting of genipin, genipin oil, dialdehydes, epoxy compounds or a combination thereof. The optional filler in the method is selected from a group consisting of one or more potato proteins, wheat bran, cereal husks, cereal straws, or a combination thereof wherein the filler is more preferably patatin. The foaming agent in the method is selected from a group consisting of bicarbonate, water or a combination thereof, preferably sodium bicarbonate. Figure 1 is an illustration of the method according to this aspect. Referring now to figure 1. A method for producing a film comprises the steps of providing zein (1), providing a second protein selected from glutenin, gliadin, secalin, hordein, avenin or a combination thereof (2), providing a plasticizer, wherein the plasticizer is preferably selected from a group consisting of glycerol, water, sorbitol, propylene glycol, diethanolamine, triethanlamine or a combination thereof (3), optionally providing a crosslinking agent selected from a group consisting of genipin, genipin oil, aglycones, dialdehydes, polycarboxylic acids, phenolic compounds, epoxy compounds or a combination thereof (4), optionally providing a filler, wherein the filler is preferably one or more potato proteins, wheat bran, cereal husk, cereal straws, or a combination thereof, wherein the filler is more preferably patatin (5). Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent, and optionally the filler (7) to form a mixture wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1. Extruding the mixture (8) to obtain a film (10). Referring to figure 1. A method for producing a porous film comprises the steps of providing zein (1), providing a second protein selected from glutenin, gliadin, secalin, hordein, avenin or a combination thereof (2), providing a plasticizer, wherein the plasticizer is preferably selected from a group consisting of glycerol, water, sorbitol, propylene glycol, diethanolamine, triethanolamine or a combination thereof (3), optionally providing a crosslinking agent selected from a group consisting of genipin, genipin oil, aglycones, dialdehydes, polycarboxylic acids, phenolic compounds, epoxy compounds or a combination thereof (4), optionally providing a filler, wherein the filler is preferably one or more potato proteins, wheat bran, cereal husk, cereal straws, or a combination thereof wherein the filler is more preferably patatin (5), providing a foaming agent selected from a group consisting of bicarbonate, water or a combination thereof, preferably sodium bicarbonate (6). Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent, optionally the filler and the foaming agent (7) to form a mixture wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1. Extruding the mixture (8) to obtain a porous film (10). Referring to figure 1. A method for producing a porous film comprises the steps of providing zein (1), providing a second protein selected from glutenin, gliadin, secalin, hordein, avenin or a combination thereof (2), providing a plasticizer, wherein the plasticizer is preferably selected from a group consisting of glycerol, water, sorbitol, propylene glycol, diethanolamine, triethanolamine or a combination thereof (3), optionally providing a crosslinking agent selected from a group consisting of genipin, genipin oil, aglycones, dialdehydes, polycarboxylic acids, phenolic compounds, epoxy compounds or a combination thereof (4), optionally providing a filler, wherein the filler is preferably one or more potato proteins, wheat bran, cereal husk, cereal straws, or a combination thereof wherein the filler is more preferably patatin (5). Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent and optionally the filler (7) to form a mixture wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1. Extruding the mixture (8), wherein gas is injected (9) during the extrusion, to obtain a porous film (10). Referring to figure 1. A method for producing a foam comprises the steps of providing zein (1), providing a second protein selected from glutenin, gliadin, secalin, hordein, avenin or a combination thereof (2), providing a plasticizer, wherein the plasticizer is preferably selected from a group consisting of glycerol, water, sorbitol, propylene glycol, diethanolamine, triethanolamine or a combination thereof (3), optionally providing a crosslinking agent selected from a group consisting of genipin, genipin oil, aglycones, dialdehydes, polycarboxylic acids, phenolic compounds, epoxy compounds or a combination thereof (4), optionally providing a filler, wherein the filler is preferably one or more potato proteins, wheat bran, cereal husk, cereal straws, or a combination thereof wherein the filler is more preferably patatin (5), providing a foaming agent selected from a group consisting of bicarbonate, water or a combination thereof, preferably sodium bicarbonate (6). Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent, optionally the filler and the foaming agent (7) to form a mixture wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1. Extruding the mixture (8) to obtain a foam (10). Referring to figure 1. A method for producing a foam comprises the steps of providing zein (1), providing a second protein selected from glutenin, gliadin, secalin, hordein, avenin or a combination thereof (2), providing a plasticizer, wherein the plasticizer is preferably selected from a group consisting of glycerol, water, sorbitol, propylene glycol, diethanolamine, triethanolamine or a combination thereof (3), optionally providing a crosslinking agent selected from a group consisting of genipin, genipin oil, aglycones, dialdehydes, polycarboxylic acids, phenolic compounds, epoxy compounds or a combination thereof (4), optionally providing a filler, wherein the filler is preferably one or more potato proteins, wheat bran, cereal husk, cereal straws, or a combination thereof wherein the filler is more preferably patain (5). Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent and optionally the filler (7) to form a mixture wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1. Extruding the mixture (8), wherein gas is injected (9) during the extrusion, to obtain a foam (10). In one embodiment, the sum of zein and the second protein is at least 50 weight-% with respect to the total weight of the mixture, preferably 60 weight-%. Extruded films of the present invention are obtained by employing dies well known in the art, preferably by employing a film die with at least 0.2 mm thickness or the like. Extruded foams of the present invention are obtained by employing dies well known in the art, preferably by employing circular dies of 2-3 mm in diameter or the like. The inventors found that foams of the material of the present invention was capable of being further processed into the desired shape. In one example the extruded foam is initially cut into pellets. Subsequently, the pellets were distributed in a mold, pressed at 150˚C and 150 kN for 5 minutes, followed by 5 minutes in the mold at 150˚C without applying pressure. Homogeneous materials, shaped according to the mold, were obtained for materials with an amount of 0.9 g / cm3. According to yet another aspect, the present invention relates to an absorbent article comprising a film, an absorbent member comprising the foam according to the first aspect of the invention, and a porous film. In conventional absorbent articles such as diapers, incontinence pads, sanitary pads, breastfeeding pad, band aid and absorbent protection bedsheets, the absorbent member is disposed between a first, porous layer, conventionally referred to as “top sheet” and a second layer, conventionally referred to as “back sheet”. Furthermore, the top sheet and the back sheet of the article may be sealed together encompassing the absorbent member. The absorbent member may comprise the foam according to the present invention as the only liquid absorbing component or may include additional liquid absorbing components to form the absorbent member. Examples of such liquid absorbing components include, but are not limited to, cellulosic fibers, protein blend fibers, synthetic fibers, and foam materials. The top sheet is a porous film that is liquid permeable, and may be any material or combination of materials suitable for this purpose, including but not limited to fibrous nonwovens, apertured plastic films and textile materials, that allows body fluids to be transported through the layer and get in contact with the absorbent member. In one embodiment the top sheet is the porous film according to the present invention. The back sheet may be of any material or combination of materials suitable for this purpose, including but not limited to non-wovens and plastic films. The back sheet may be liquid impermeable to prevent leakage of body fluids. The back sheet may be vapour permeable, to allow vapour to pass through. In one embodiment, the back sheet is the film according to the present invention. In one embodiment, the top sheet is welded to the back sheet by employing an impulse sealer or the like. Wherein the top sheet and the back sheet completely enclose the absorbent member. In one embodiment, the absorbent article is biodegradable in soil comprising farmland and compost at a weight ratio of 2:1, at room temperature and 70-80% relative humidity within 30 days. In one embodiment, the absorbent article exhibit no mold growth after 3 weeks exposure to 100% relative humidity at 25˚C. It is to be understood that the absorbent member comprising the foam according to the present invention may be the foam as obtained after extrusion, grinded particles of the foam, or the foam molded in a desired shape. EXAMPLES Example 1 – Foams constructed from zein, wheat gluten and potato protein 1.1 Materials Wheat gluten concentrate (WG) was obtained as a coproduct from the industrial wheat starch production / extraction, with protein content of 86.3±0.3%, determined by the Dumas method, NMLK 6:2003. Potato protein concentrate (PP) from the production / extraction of potato starch was used, with a protein content of 82±2%, determined by the Dumas method. Zein (Z) (C-zein, CAS number: 9010-66-6, product number Z3625) was purchased from Sigma-Aldrich Co. (St Louis, MO, USA). Glycerol (ACS ≥99.5% reagent) and sodium bicarbonate (SBC) (NaHCO3, ACS ≥98%) were purchased from Sigma-Aldrich (Stockholm, Sweden). Genipin (GEN) (HPLC grade ≥98%) was purchased from Zhixin Biotechnology, China. Genipin oil (OIL) was obtained as the liquid product collected by extraction of oelic substances (such as genipin) contained in the fruit of the Rubiaceae trees family. 1.2 Preparation of foam Dry Z, WG and PP powders were mixed at different weight ratios, namely Z:WG:PP of 75:25:0 (0% PP), 60:25:15 (15% PP), 50:25:25 (25% PP), 40:25:35 (35% PP), 30:25:45 (45% PP), and 25:25:50 (50% PP). SBC was added as a foaming agent in the ratio of 5 g per 100 g of proteins. Samples were prepared with different ratios between zein and wheat gluten, spanning from 3:1 to 1:1, with potato protein as a filler. Additionally, samples were prepared without a crosslinking agent, with the addition of 2.5 g of GEN per 100 g of proteins as a crosslinking agent, as well as with the addition of 2.5 g of OIL per 100 g of proteins as the crosslinking agent, respectively. The powders were mixed with an electric mixer for 30 seconds, followed by the addition of 50 g of glycerol per 100 g of proteins as a plasticizer, followed by mixing with an electric mixer for another 30 seconds. The mixtures were immediately transferred to a conical, fully intermeshing, and co- rotating double-screw extruder (DSM Xplore 5 cc, The Netherlands). The extruder contained a screw with an L / D ratio of 8 and a compression ratio of 3.3. All heating zones of the extruder were set to the temperature of 110˚C, a screw speed of 90 rpm was set, and a circular die with a diameter of 3.8 mm was used during extrusion. Table 1: Sample composition S g 7 6 5 4 3 2 7 6 5 4 3 2 7 6 5 4 3 2 1.3 Absorption capacity Water swelling capacity was determined by completely immersing samples of 1 cm long foam pieces in water for 24 hours. After removing the samples from the liquid, excess liquid was removed by placing the samples on tissue paper for 10 seconds. Water swelling capacity was calculated according to ^^− (^^− ^^ ^) ^^^^^ ^^^^^^^^ ^^^^^^^^ = (^^− ^^^) for which W2denotes the swollen weight of the sample, W1denotes the dry weight of the sample, W’1 denotes the dry weight of the sample after swelling. Figure 2 depicts photographs of extruded foam samples prior to and after immersion in water for 24 hours; a) 75Z / 0PP, b) 60Z / 15PP, c) 50Z / 25PP, d) 40Z / 35PP, e) 30Z / 45PP and f) 25Z / 50PP. All samples swollen in water for 24 hours showed structural stability, and retained their cylindrical shape, as seen in Figure 2. Figure 3 shows water swelling capacities of samples according to Table 1. Samples 75Z / 0PP, 75Z / 0PPGEN, 75Z / 0PPOIL, 60Z / 15PP, 60Z / 15PPGEN, 60Z / 15PPOILexhibited water swelling capacities of 333%, 471%, 356%, 252%, 288%, and 280%, respectively, as seen in Figure 3. The water swelling capacity decreased with increasing filler content in the material. Table 2: Water swelling capacity of selected samples 7L3 Free swelling capacities were determined according to Non-woven Standard Procedure (NWSP) 240.0.R2, also known as the “teabag” test, and in accordance with International Standard ISO 17190-5 (2020). An amount of 300 mg of the dry extruded foam, previously pulverized in liquid nitrogen, was added to a nonwoven fabric bag having a dimension of 40 x 60 mm2(mesh=400). The bags containing the samples were hooked on a rod and immersed in a beaker containing 0.9 weight-% NaCl aqueous solution, to simulate body fluids. The immersion times were 1, 5, 10, 30, and 1440 minutes and the working temperature was 25˚C. The bags with the samples were removed from the saline solution hung for 10 seconds, and placed on a paper for 10 seconds to remove the unabsorbed solution. Three empty bags were subjected to the same process to obtain an average correction factor (Wb) using the following equation = ^ where WS denotes the weight of the wet bag and W denotes the weight of the dry bag. Free swelling capacity (FSC) was calculated according to the following equation ([^^−(^^∙ ^^)] − ^^) where Widenotes the weight of the swollen sample, W0denotes the weight of the dry bag used, Wd denotes the weight of the sample, and Wb denotes the correction factor. Figure 4 shows the free swelling capacities in saline solution for selected samples of Table 1. The highest FSC after 1 minute were obtained for 60Z / 15PPOILand 60Z / 15PPGENwith approximately 8 g of saline per gram of material. The lowest FSC after 1 minute were obtained for 25Z / 50PPOILwith 5 g of saline per gram of material. The highest FSC after 24 hours was obtained for 60Z / 15PPOILwith 11 g of saline solution per gram of material, followed by 75Z / 0PP, 75Z / 0PPGEN, 75Z / 0PPOIL, and 60Z / 15PP, all with approximately 10 g / g, followed by 60Z / 15PPGENwith 9 g / g. The lowest FSC after 24 hours was obtained for samples with the highest portion of PP, i.e. 25Z / 50PP, 25Z / 50PPGEN, and 25Z / 50PPOILwith 7 g / g, 6 g / g, and 8 g / g, respectively. Centrifuge retention capacities (CRC) were determined to measure the fluid retention of samples of the dry extruded foam, previously pulverized in liquid nitrogen. An amount of 300 mg of sample was added to a nonwoven fabric bag with a dimension of 40 x 60 mm2(mesh=400). The bags containing the samples were hooked on a rod and immersed in a beaker containing 0.9 weight-% NaCl aqueous solution, to simulate body fluids. The immersion time was 30 minutes and the working temperature was 25˚C. The bags with the samples were removed from the saline solution, hung for 10 seconds, and placed on paper for 10 seconds to remove the unabsorbed solution. Samples, kept inside the teabags, were centrifuged for 3 minutes at 1250 rpm. CRC the equation below ^^where Wcdenotes the weight of the centrifuged sample in the bag, W0denotes the weight of the dry bag used, Wd denotes the weight of the sample, and Wb denotes the correction factor. In turn, the correction factor is calculated according to ^ ^ =^^where WSdenotes the weight of the W is the weight of the dry bag. Figure 5 depicts the centrifuge retention capacity (CRC) of selected samples from Table 1. The highest CRC value was obtained for 60Z / 15PPOILwith 3.3 g / g, indicating that 330% of the saline solution was strongly retained within the material. Example 2 – Absorbent article with protein blend materials 2.1Materials Wheat gluten concentrate (WG) was obtained as a coproduct from the industrial wheat starch production / extraction, with a protein content present in the WG was 86%, determined by the Dumas method, NMLK 6:2003. Zein (Z) (C-zein, CAS number: 9010-66-6, product number Z3625) was purchased from Sigma-Aldrich Co. (St Louis, MO, USA). Glycerol (ACS ≥99.5% reagent) and sodium bicarbonate (SBC) (NaHCO3, >99.7%) were purchased from Fischer Scientific and Sigma-Aldrich (Stockholm, Sweden), respectively. 2.2Film preparation Before extrusion, the dry Z and WG were mixed at a weight ratio of 3:1 with an electric mixer for 30 seconds, followed by adding 50 g of glycerol per 100 g of proteins as a plasticizer, followed by mixing with an electric mixer for another 30 seconds. The mixtures were immediately transferred to a conical, fully intermeshing, and co- rotating double-screw extruder (DSM Xplore 5 cc, The Netherlands). The extruder contained a screw with an L / D ratio of 8 and a compression ratio of 3.3. All heating zones of the extruder were set to the temperature of 100˚C, a screw speed of 60 rpm was set, and a flat sheet die of 0.2 mm was used during extrusion. 2.3Porous film preparation Prior to extruding, the dry Z and WG were mixed at a weight ratio of 3:1 with an electric mixer for 30 seconds, followed by the addition of 50 g of glycerol per 100 g of proteins as a plasticizer as well as 5 g of SBC per 100 g of proteins as foaming agent and 5 g of water per 100 g of protein as plasticizer and / or foaming agent, followed by mixing with an electric mixer for another 30 seconds. The mixtures were immediately transferred to a conical, fully intermeshing, and co- rotating double-screw extruder (DSM Xplore 5 cc, The Netherlands). The extruder contained a screw with an L / D ratio of 8 and a compression ratio of 3.3. All heating zones of the extruder were set to the temperature of 100˚C, a screw speed of 60 rpm was set, and a flat sheet die of 0.2 mm was used during extrusion. 2.4Foam preparation Prior to extruding, the dry Z and WG were mixed at a weight ratio of 3:1 with an electric mixer for 30 seconds, followed by the addition of 50 g of glycerol per 100 g of proteins as a plasticizer as well as 5 g of SBC per 100 g of proteins as foaming agent and 5 g of water per 100 g of protein as plasticizer and / or foaming agent, followed by mixing with an electric mixer for another 30 seconds. The mixtures were immediately transferred to a conical, fully intermeshing, and co- rotating double-screw extruder (DSM Xplore 5 cc, The Netherlands). The extruder contained a screw with an L / D ratio of 8 and a compression ratio of 3.3. All heating zones of the extruder were set to the temperature of 100˚C, a screw speed of 60 rpm was set, and a circular die with a diameter of 4 mm was used during extrusion. 2.5Absorbent article assembly Foam extrudate was cut into 0.5 cm pellets. The pellets were put in a pre-heated aluminum mold. The mold was placed between anti-adhesion Telfon® paper and top and bottom plates preheated to 150˚C. The pellets were pressed at 150˚C and 150 kN for 5 minutes, followed by 5 minutes at 150˚C without applied pressure.0.9 g / cm3of material with respect to volume of the mold was used. The molded pad was stored in desiccator. Absorbent articles were assembled with conventional materials as well as with protein based materials, summarized in table 3 below. The foam was sealed between a back sheet of a film and a top sheet of a porous film by using an impulse sealer (PFS-400). Protein based film, porous film and foam are disclosed in section 2.2, 2.4, and 2.3 above, respectively. Ta S indexiPolypropylene / polyethylene Polyurethane Polypropylene / polyethylene iiiii Figure 6 illustrates a photograph of absorbent articles, from left to right i) polypropylene / polyethylene nonwoven film and porous film with polyurethane foam, ii) polypropylene / polyethylene nonwoven film and porous film with protein based foam, iii) protein based film, protein based porous film and polyurethane foam, iv) protein based film, protein based porous film with protein based foam. Example 3 – Blood absorption capacity 3.1 Film, foam and porous film preparation Films, foams, and porous films were prepared according to example 2. Additionally, a filament was prepared according to the same manner as the foam, but without the addition of foaming agent. That is by prior to extrusion, mixing the dry Z and WG at a weight ratio of 3:1 with an electric mixer for 30 seconds, followed by the addition of 50 g of glycerol per 100 g of proteins as a plasticizer, followed by mixing with an electric mixer for another 30 seconds. The mixtures were immediately transferred to a conical, fully intermeshing, and co- rotating double-screw extruder (DSM Xplore 5 cc, The Netherlands). The extruder contained a screw with an L / D ratio of 8 and a compression ratio of 3.3. All heating zones of the extruder were set to the temperature of 100˚C, a screw speed of 60 rpm was set, and a circular die with a diameter of 4 mm was used during extrusion. 3.2 Samples "Filament” samples were the cut from the extrudate prepared without the addition of foaming agent. “Hot pressed samples” were prepared by cutting the foam extrudate into 0.5 cm pellets. The pellets were put in a pre-heated aluminum mold. The mold was placed between anti-adhesion Teflon® paper and top and bottom plates pre-heated to 150˚C. The pellets were pressed at 150˚C and 150 kN for 5 minutes, followed by 5 minutes at 150˚C without applied pressure. 0.9 g / cm3of material with respect to the volume of the mold was used. Figure 7 illustrates photographs of the “hot pressed sample” shaped as a conventional sanitary pad, before bending (left), arched by hand (center), as well as after bending (right). “Particle samples” were prepared by cryogenic grinding. Two types of absorbent articles were prepared; with polypropylene / polyethylene film, hot pressed sample as foam, and polypropylene / polyethylene porous film, or with protein based film, hot pressed sample as foam, and protein based porous film. 3.4 Blood absorption capacity A visual absorption test was employed to assess the blood absorption capacity. Defibrinated sheep blood was added to the material until saturation was reached. Additionally, the amount of blood was measured by mass and normalized with respect to the dry sample weight. Figure 8 illustrates photographs of the visual absorption test of a) hot pressed sample, b) particle sample, c) an absorbent article with polypropylene / polyethylene film and porous film, and d) an absorbent article with protein based film and porous film according to the sample preparation described in section 3.2. The blood absorption capacity of the hot pressed samples was 4.2 g / g. The blood absorption capacity of the particle samples was 4 g / g. The absorbent article assembled with polypropylene / polyethylene film and porous film did not spread the blood adequately, and the droplet stayed on the material’s surface. The same behavior was observed on a commercial sanitary product. The absorbent article assembled with protein based film and porous film with a hot pressed sample as foam exhibited a blood absorption capacity of 0.7 g / g. The blood absorption capacity of the filament sample was 0.4 g / g. Example 4 – Absorption under load 4.1 Foam The foam was prepared according to example 2. 4.2 Absorption under load The capacity of the material to absorb liquid under a constant load was determined by the absorption under load (AUL) test following the NWSP 242.0.R2 standard. The sample was placed in a cylinder having a metal grid at the bottom and a piston was placed on top of the sample. The piston had a weight of 0.5 kg and a diameter of 6 cm, leaving a pressure of approximately 1.76 kPa (0.25 psi, equivalent to a new born baby). The setup was placed on top of a porous ceramic plate, in a glass petri dish. Saline solution (0.9 weight-% NaCl) was added to the petri dish, contacting the sample via the metal grid. The sample was left under load for 1 hour. The foam exhibited an absorption under load of 0.6±0.1 g / g. Example 5 – Biodegradation 5.1 Foam The foam was prepared according to example 1. 5.2 Biodegradation The biodegradation of the material was evaluated by monitoring the disintegration of the sample in soil over time. Samples were buried in a soil of farmland and compost at a weight ratio of 2:1, at room temperature and 70-80% relative humidity. The samples were unearthed after 5 days, 14 days, 30 days and 43 days, respectively, to evaluate the visual appearance of the samples. Figure 9 illustrates photographs of samples prior to and after degradation in soil for 5 days, 14 days and 30 days, respectively. In the case with no photographic record, it was because no pieces larger than 1 mm were found. As seen in Figure 9 a higher potato protein content result in faster degradation of the material. Example 6- Hydrolytic degradation 6.1 Foam The foams were prepared according to example 1. 6.2 Hydrolytic degradation The hydrolytic degradation of the samples was evaluated at 25˚C and in three degradation systems: an acid pH 4 buffer solution (sodium acetate / acetic acid), a neutral pH 7 buffer solution (PBS), and a basic pH 9 buffer solution (ammonium chloride / ammonia). The time of degradation was of one, three and five weeks. Degradation monitoring was done by monitoring weight changes, pH variation of the degradation medium and morphological changes by scanning electron microscopy. For all samples, 33% of the weight loss is attributed to the leaching of plasticizer, i.e. glycerol, within the first week. Weight loss above 33% is attributed to hydrolysis of proteins in the material followed by dissolution of the hydrolysis products from the samples. Generally, the weight loss was higher for all samples in pH 8.83 than for pH 4.44 and pH 7.38. Figure 10 depicts weight loss of samples after 1, 3, and 5 weeks in pH 7.38 buffer solution, without crosslinking agent (top), with genipin as crosslinking agent (middle), and with genipin oil as crosslinking agent (bottom). The line at 33% highlight the weight loss attributed to leaching of plasticizer. After 5 weeks in pH 7.38, samples without crosslinking agent (Control) exhibited weight loss ranging from 45% to 53%, whereas samples with crosslinking agent (GEN or OIL) exhibited a weight loss ranging from 35% to 46%. These results indicate that addition of crosslinking agent delays the hydrolysis of the proteins in the material. Example 7- Mold resistance test 7.1 Foam The foams were prepared according to example 1. 7.2 Mold resistance test A visual test was used to evaluate the mold resistance of samples in powder form as well as extruded foams. 0.5 g of samples were placed in culture dishes in an airtight container with at 25˚C and 100% relative humidity. Photographs of the samples were taken after 0, 1, 3, and 5 weeks. Figure 11 depicts photographs of extruded foam and grounded foam of samples a) 40Z / 35PP, b) 40Z / 35PPGEN, and c) 40Z / 35PPOILprior to as well as after 1, 3 and 5 weeks. As seen in Figure 11, no presence of mold was found on the powder sample and extruded foam sample of 40Z / 35PP and 40Z / 35PPGEN. Mold was observed for the powder sample as well as the extruded foam of 40 / 35PPOIL. These samples, composed of a blend of zein and gluten, exhibited a considerable increase in shelf life compared to what has previously been obtained for 100% gluten based materials, which exhibit mold attack within 2 weeks. Example 8 – Material without second protein 8.1 Materials Materials were used according to example 1. 8.2 Extrusion of material Dry Z and SBC (as a foaming agent) in the ratio of 5 g per 100 g of Z were mixed with an electric mixer for 30 seconds, followed by the addition of 50 g of glycerol (as a plasticizer) per 100 g of Z, followed by mixing with an electric mixer for another 30 seconds. The mixture was immediately transferred to a conical, fully intermeshing, and co- rotating double-screw extruder (DSM Xplore 5 cc, The Netherlands). The extruder contained a screw with an L / D ratio of 8 and a compression ratio of 3.3. All heating zones of the extruder were set to the temperature of 100˚C, a screw speed of 60 rpm was set, and a circular die with a diameter of 3.8 mm was used during extrusion. 8.3 Material characterization Figure 12 shows a photograph of the extruded material. The sample was very brittle, tacky during extrusion, and it contains a non-continuous pore microstructure which is partially collapsed. Example 9 Foam preparation: Two samples were prepared. Prior to extrusion, the dry Z and WG were mixed at a weight ratio of 3:1 or 1:1, respectively, with an electric mixer for 30 seconds, followed by the addition of 50 g of glycerol per 100 g of proteins as a plasticizer as well as 5 g of SBC per 100 g of proteins as foaming agent and 5 g of water per 100 g of protein as plasticizer and / or foaming agent, followed by mixing with an electric mixer for another 30 seconds. The Z and WG mixtures were immediately transferred to a conical, fully intermeshing, and co-rotating double-screw extruder (DSM Xplore 5 cc, The Netherlands). The extruder contained a screw with an L / D ratio of 8 and a compression ratio of 3.3. All heating zones of the extruder were set to the temperature of 120˚C, a screw speed of 90 rpm was set, and a circular die with a diameter of 4 mm was used during extrusion. Biodegradation of samples of example 9 The biodegradation of the material was evaluated by monitoring the disintegration of the sample in soil over time. Samples were buried in a soil of farmland and compost at a weight ratio of 2:1, at room temperature and 70-80% relative humidity. The samples were fully degradable in less than 30 days. Hydrolytic degradation of samples of example 9 The hydrolytic degradation of the samples was evaluated at 25˚C and in a neutral pH 7 buffer solution (PBS). The samples were hydrolytically degradable of 70 weight-% in 7 weeks. Mold resistance of samples of example 9 A visual test was used to evaluate the mold resistance. 0.5 g of the samples were placed in culture dishes in an airtight container with at 25˚C and 100% relative humidity. The samples exhibited mold resistance up to 2 months. Blood absorption of samples of example 9 A visual absorption test was employed to assess the blood absorption capacity. Defibrinated sheep blood was added to the material until saturation was reached. Additionally, the amount of blood was measured by mass and normalized with respect to the dry sample weight. The samples exhibited a blood absorption of at least 1 g of blood per gram of dry material in 10 min. Saline solution absorption of samples of example 9 A visual absorption test was employed to assess the saline solution absorption capacity. Saline solution (0.9 weight-% NaCl in water) was added to the material until saturation was reached. Additionally, the amount of saline solution was measured by mass and normalized with respect to the dry sample weight. The samples exhibited a saline solution absorption of at least 3 g of saline solution per gram of dry material.

Claims

CLAIMS 1. A material comprising i) A first protein, wherein the first protein is zein, ii) A second protein selected from a group consisting of glutenin, gliadin, secalin, hordein, avenin or a combination thereof, and iii) A plasticizer, wherein the material has a weight ratio between zein and the second protein between 1:1 and 4:1, preferably between 1:1 and 3:

1.

2. The material according to claim 1, wherein the material is at least partly crosslinked, and wherein the material comprises 0.05-5 weight-% crosslinking agent, preferably 0.5-1.5 weight-%, wherein the crosslinking agent is preferably selected from a group consisting of genipin, genipin oil, aglycone, dialdehydes, polycarboxylic acids, phenolic compounds, epoxy compounds or a combination thereof, wherein the crosslinking agent is more preferably genipin or genipin oil.

3. The material according to claim 1-2, wherein the sum of zein and the second protein is at least 50 weight-%, preferably 60 weight-%, wherein the plasticizer is preferably selected from a group consisting of glycerol, water, sorbitol, propylene glycol, diethanolamine, triethanolamine or a combination thereof, wherein the material preferably comprises 20-40 weight-% plasticizer, more preferably 25-35 weight-%.

4. The material according to claim 1-3, wherein the material comprises 5-15 weight-% filler, wherein the filler is preferably one or more potato proteins, wheat bran, cereal husks, cereal straws or a combination thereof, wherein the filler is more preferably patatin.

5. The material according to claim 1-4, wherein the material is a foam, film or a porous film.

6. A method for producing a film, a porous film or a foam comprising a. Providing zein,b. Providing a second protein selected from a group consisting of glutenin, gliadin, secalin, hordein, avenin or a combination thereof, c. Providing a plasticizer, wherein the plasticizer is preferably selected from a group consisting of glycerol, water, sorbitol, propylene glycol, diethanolamine, triethanolamine or a combination thereof, d. Optionally providing a crosslinking agent selected from a group consisting of genipin, genipin oil, dialdehydes, epoxy compounds or a combination thereof, e. Optionally providing a filler, wherein the filler is preferably one or more potato proteins, wheat bran, cereal husks, cereal straws or a combination thereof wherein the filler is more preferably patatin, and wherein the film is produced by performing steps A1 and A2, and wherein said steps comprises: A1. Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent and optionally the filler to form a mixture, wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1, and A2. Extruding the mixture to a film; wherein the porous film or foam is produced either by performing steps B1, B2 and B3, and wherein said steps comprises: B1. Providing a foaming agent, wherein the foaming agent is selected from a group consisting of bicarbonate, water or a combination thereof, preferably sodium bicarbonate, and B2. Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent, optionally the filler and the foaming agent to form a mixture, wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1, and B3. Extruding the mixture to a porous film or a foam or wherein the porous film or foam is produced by performing steps C1 and C2, and wherein said steps comprises: C1. Mixing zein, the second protein, the plasticizer, optionally the crosslinking agent and optionally the filler to form a mixture, wherein the weight ratio between zein and the second protein is between 1:1 and 4:1, preferably between 1:1 and 3:1, and C2. Extruding the mixture, wherein gas is injected to the mixture during the extrusion, to a porous film or a foam.

7. The method according to claim 6, wherein the sum of zein and the second protein is at least 50 weight-%, preferably 60 weight-%, wherein the mixture comprises 20-40 weight-% plasticizer.

8. An absorbent article comprising a. A film, b. An absorbent member comprising the foam according to any one of claim 1-5, and c. A porous film, and Wherein the absorbent member is arranged between the film and the porous film.

9. The absorbent article according to claim 8, wherein the film and / or the porous film is a material according to claim 1-5. 10.The absorbent article according to claim 8-9, wherein the absorbent article is a diaper, incontinence pad, sanitary pad, breastfeeding pad, band aid, absorbent protection bedsheet, single-use liquid absorbent amendment product.

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