Bio-based adhesive composition and method of making the same

Abstract

A bio-based adhesive composition and a method of making the same are provided. In one embodiment, the bio-based adhesive composition comprises: a) 0.01 to 60 wt.% of a polyphenol; b) 0.5 to 90 wt.% of a first bio-based polymer comprising a plurality of amino or hydroxyl groups as a first Michael donor for a first Michael addition reaction with a first Michael acceptor formed by oxidizing the polyphenol; c) 0.5 to 90 wt.% of a second bio-based polymer; d) 0.01 to 50 wt.% of a metal compound selected from aluminum (III), calcium (II), copper (II), gold (III), silver (I), titanium (IV), sodium (I), and zinc (II) compounds; and e) 1 to 99 wt.% of a protic solvent; wherein the bio-based adhesive composition can be conditioned to form a transparent polymer network crosslinked by covalent and non-covalent interactions.

Description

[0001] Invention Field

[0002] This invention relates to bio-based adhesives and their preparation methods. Background of the Invention

[0004] A binder is a matrix or molecule that allows two materials or two reaction sites to be linked at the molecular level. The term "binder" is often used interchangeably with "adhesive," which refers to any substance that can bind two materials together while resisting separation by external forces. In fact, adhesion is just one application of binders. By definition, an adhesive is a substance that provides or promotes adhesion, such as glue; while a binder is a substance that brings two other substances together, for example, in pigment printing, binders are incorporated into the paste formulation along with the pigment.

[0005] In recent decades, various applications of adhesive binders have been developed. Adhesives are used to bond two surfaces or materials together, such as paper, glass surfaces, or in construction work using wood or metal. The adhesive used depends on the strength required for the application. For example, the cellulose-cellulose bond between starch glue and paper is sufficient for everyday work, virtually harmless, and easy to handle. On the other hand, the harmful super glue (AA glue) commonly used to bond wood and glass contains methyl 2-cyanoacrylate, which irritates and burns the skin and eyes, and also irritates the nose and throat, causing coughing and wheezing (Methyl 2-cyanoacrylate Hazardous Substance Fact Sheet, 2000). The enormous adhesion is attributed to the strong covalent bonds between α-cyanoacrylate and the adhered material, compared to the relatively weak hydrogen bonds used in starch glue or white polyvinyl acetate (PVAc) glue.

[0006] Traditional adhesives contain flammable and / or harmful compounds / chemicals, as shown in the Acrylic Glue Safety Data Sheet (2016), Polyurethane Contact Adhesive Safety Data Sheet (2012), and Styrene Adhesive Safety Data Sheet (2018).

[0007] Adhesives also play a crucial role in surgical repair and wound closure. Bioadhesives can overcome the contours of tissue surfaces through a robust cross-linked network (Liu, et al., 2017). Furthermore, these bioadhesives may help reduce the chance of infection while improving the efficacy of therapeutic drugs (Pinnaratip, Bhuiyan, Meyers, Rajachar, & Lee, 2019). As bioadhesives, they are expected to be used in the presence of water and blood (and sometimes sweat). Therefore, it is necessary to achieve strong adhesion under moist or aqueous conditions.

[0008] Patents US20210207008A1 and CN113088243A disclose a catechol-containing polymer additive and its application in polymer adhesives and sealants for various applications on dry and wet surfaces. The invention is inspired by proteins containing high levels of catechol groups produced by mussel byssal silks. The adhesive comprises a first component (a polysiloxane or polyurethane adhesive) and a second component (a catechol-containing polymer additive). The catechol-containing polymer additive in the described polymer adhesive is a reaction product of polyvinylpyrrolidone (PVP) (a synthetic polymer derived from petroleum resources) and 3',4'-dihydroxy-2-chloroacetophenone (a reaction product of pyrocatechol and chloroacetic acid).

[0009] Patent US2018 / 0256777A1 discloses an adhesive for underwater adhesion having a polymer core that is a 4-arm, 6-arm, or 8-arm polyethylene oxide substituted with at least one L-3,4-dihydroxyphenylalanine (L-DOPA) group and at least one thiol reactive group. Hazardous chemicals, including acetone and dichloromethane, are used in the synthesis of the described adhesive.

[0010] Patent US8916652B2 discloses a mixture of multi-armed catechol compounds obtained by chemical synthesis of polyethylene glycol and polyhydroxyphenyl derivatives. However, this synthesis involves hazardous chemicals including chloroform and DMF.

[0011] Patent WO 2023 / 114321 A1 discloses a bio-based adhesive suitable for use on wet surfaces and underwater. The described underwater adhesive composition comprises (i) zein, (ii) tannic acid, (iii) an inorganic filler, and (iv) a natural polymer (protein or polysaccharide), wherein the composition contains about 30-80 wt% tannic acid. The adhesive composition may also contain FeCl3. Due to the use of high contents of zein and tannic acid, the described adhesive is amber in color. The preparation of the described adhesive involves only dissolving and mixing the components in a solvent (ethanol and water). Heating is not required. The patent does not mention the types of interactions involved in the adhesive, but due to the method of preparation of the adhesive, covalent bonds are unlikely to form.

[0012] The present invention provides an adhesive that solves the aforementioned problems associated with existing adhesives. Summary of the Invention

[0013] This invention provides a bio-based adhesive composition. In one embodiment, the bio-based adhesive composition comprises: a) 0.01 to 60 wt.% of a polyphenol; b) 0.5 to 90 wt.% of a first bio-based polymer comprising a plurality of amino or hydroxyl groups as a first Michael donor for a first Michael addition reaction with a first Michael acceptor formed by oxidation of the polyphenol; c) 0.5 to 90 wt.% of a second bio-based polymer; d) 0.01 to 50 wt.% of a metal compound selected from aluminum(III), calcium(II), copper(II), gold(III), silver(I), titanium(IV), sodium(I), and zinc(II) compounds; and e) 1 to 99 wt.% of a proton solvent; wherein the bio-based adhesive composition can be adapted to conditions for forming a transparent polymer network crosslinked by covalent and non-covalent interactions.

[0014] The present invention also provides an article comprising a substrate coated with the bio-based adhesive composition of the present invention.

[0015] The present invention also provides a method for preparing the bio-based adhesive of the present invention. In one embodiment, the method includes the following steps: a) providing a bio-based adhesive composition comprising: i) 0.01 to 60 wt.% of a polyphenol; ii) 0.5 to 90 wt.% of a first bio-based polymer comprising a plurality of first Michael donors for a first Michael addition reaction with a first Michael acceptor formed by oxidation of the polyphenol; iii) 0.5 to 90 wt.% of a second bio-based polymer; iv) 0.01 to 50 wt.% of a metal compound; and v) 1 to 99 wt.% of a proton solvent; b) dissolving the bio-based adhesive composition at 15 to 95°C and oxidizing the polyphenol to form a first solution; c) adjusting the first solution to a pH favorable to the first Michael addition reaction to form a second solution; and d) adjusting the second solution to a suitable pH to form the bio-based adhesive.

[0016] Brief description of the attached figures

[0017] The complete and practicable disclosure of the present invention, including its preferred embodiments, will be apparent to those skilled in the art, and is set forth in more detail in the remainder of the specification, which includes reference to the accompanying drawings, wherein: Figure 1 An exemplary process for preparing and applying adhesive compositions is illustrated. Invention Details

[0019] This invention provides a bio-based adhesive composition. In one embodiment, the bio-based adhesive composition comprises: a) 0.01 to 60 wt.% of a polyphenol; b) 0.5 to 90 wt.% of a first bio-based polymer comprising a plurality of amino or hydroxyl groups as a first Michael donor for a first Michael addition reaction with a first Michael acceptor formed by oxidation of the polyphenol; c) 0.5 to 90 wt.% of a second bio-based polymer; d) 0.01 to 50 wt.% of a metal compound selected from aluminum(III), calcium(II), copper(II), gold(III), silver(I), titanium(IV), sodium(I), and zinc(II) compounds; and e) 1 to 99 wt.% of a proton solvent; wherein the bio-based adhesive composition can be adapted to conditions for forming a transparent polymer network crosslinked by covalent and non-covalent interactions.

[0020] In one embodiment, the first Michael donor comprises two amino groups: an amino group and a hydroxyl group.

[0021] In one embodiment, the second bio-based polymer contains a plurality of amino or hydroxyl groups as a second Michael donor for a second Michael addition reaction with a second Michael acceptor formed by oxidizing the polyphenol.

[0022] In one embodiment, the second Michael donor is an amino or hydroxyl group different from the first Michael donor.

[0023] In one embodiment, the polyphenols include one or more of tannic acid, tannin, phenolic acid, flavonoids, lignin, lignans, or stilbene compounds; the first or second bio-based polymer includes one or more of cellulose, polyvinyl alcohol, chitosan, or gelatin; or the proton solvent includes water or alcohol.

[0024] In one embodiment, the conditions include dissolving the bio-based adhesive composition at a temperature of 15 to 95°C while oxidizing the polyphenols.

[0025] In one embodiment, the conditions further include adjusting and maintaining a pH value suitable for the first or second Michael addition reaction.

[0026] In one embodiment, the conditions further include adjusting the pH to neutral and cooling to room temperature.

[0027] In one embodiment, the bio-based adhesive composition is a composition selected from the group consisting of: i) tannic acid, polyvinyl alcohol, gelatin, aluminum chloride hexahydrate, and water; ii) tannic acid, polyvinyl alcohol, gelatin, calcium chloride, and water; iii) tannic acid, polyvinyl alcohol, gelatin, zinc chloride, and water; and iv) tannic acid, polyvinyl alcohol, gelatin, sodium chloride, and water.

[0028] The present invention also provides an article comprising a substrate coated with the bio-based adhesive composition of the present invention.

[0029] In one embodiment, the substrate comprises synthetic or natural materials.

[0030] The present invention also provides a method for preparing the bio-based adhesive of the present invention. In one embodiment, the method includes the following steps: a) providing a bio-based adhesive composition comprising: i) 0.01 to 60 wt.% of a polyphenol; ii) 0.5 to 90 wt.% of a first bio-based polymer comprising a plurality of first Michael donors for a first Michael addition reaction with a first Michael acceptor formed by oxidation of the polyphenol; iii) 0.5 to 90 wt.% of a second bio-based polymer; iv) 0.01 to 50 wt.% of a metal compound; and v) 1 to 99 wt.% of a proton solvent; b) dissolving the bio-based adhesive composition at 15 to 95°C and oxidizing the polyphenol to form a first solution; c) adjusting the first solution to a pH favorable to the first Michael addition reaction to form a second solution; and d) adjusting the second solution to a suitable pH to form the bio-based adhesive.

[0031] In one embodiment, the second bio-based polymer comprises a plurality of second Michael donors for a second Michael addition reaction with a second Michael acceptor formed by oxidation of the polyphenol, and step (c) further comprises adjusting the first solution to a pH favorable to the second Michael addition reaction to form the second solution.

[0032] In one embodiment, the bio-based adhesive composition is a composition selected from the group consisting of: i) tannic acid, polyvinyl alcohol, gelatin, aluminum chloride hexahydrate, and water; ii) tannic acid, polyvinyl alcohol, gelatin, calcium chloride, and water; iii) tannic acid, polyvinyl alcohol, gelatin, zinc chloride, and water; and iv) tannic acid, polyvinyl alcohol, gelatin, sodium chloride, and water.

[0033] In one embodiment, the method further includes one or more of the following steps: a) the temperature of step (b) is 80 to 90°C; b) the oxidation of step (b) includes bubbling air into the first solution; c) the pH value of step (c) is pH 7 to 10; d) step (c) includes further oxidation of the polyphenol; and e) the suitable pH value of step (d) is neutral.

[0034] Various embodiments of the present invention relate to a composition comprising at least (A) polyphenols derived from natural resources, including tannins, phenolic acids, flavonoids, lignin, lignans, stilbene compounds, etc.; (B) a first bio-based polymer selected from at least one polymer: i) a polymer containing multiple amino groups, or ii) a polymer containing multiple hydroxyl groups, or iii) a polymer containing both multiple amino groups and multiple hydroxyl groups, such as cellulose, polyvinyl alcohol derived from sugarcane alcohol, chitosan, gelatin, etc.; and (C) a second bio-based polymer selected from at least one polymer: i) a polymer containing multiple amino groups, or ii) a polymer containing multiple hydroxyl groups, or iii) a polymer containing both multiple amino groups and multiple hydroxyl groups, such as cellulose, polyvinyl alcohol derived from sugarcane alcohol, chitosan, gelatin, etc. The selection criteria for the first and second polymers are: (i) at least one of the first or second polymers contains a plurality of amino groups for Michael addition with oxidized polyphenols; or (ii) both the first and second polymers contain a plurality of amino groups for Michael addition with oxidized polyphenols, but they are not the same; or (iii) both the first and second polymers contain a plurality of hydroxyl groups and a plurality of amino groups for Michael addition with oxidized polyphenols, but they are not the same; (D) a metal compound, including aluminum (III), calcium (II), copper (II), gold (III), silver (I), titanium (IV), zinc (II), etc.; and (E) a solvent system, including water and alcohol. In one embodiment, an adhesive composition, a coating substrate, and articles of manufacture using the adhesive composition and coating substrate described herein are provided.

[0035] This invention provides an advanced, bio-based, formaldehyde-free adhesive, developed by selecting raw materials from natural resources and employing a low-energy production process and a non-toxic solvent system. This results in a waterproof adhesive that exhibits good adhesion to various substrates, is light in color, and odorless. The adhesive composition comprises a polyphenolic compound, including (A) tannic acid, (B) a first polymer having multiple amino groups and / or multiple hydroxyl groups, (C) a second polymer having multiple amino groups and / or multiple hydroxyl groups, (D) a metal compound, and (E) a solvent including water and an alcohol.

[0036] In one embodiment, the adhesive composition comprises at least the following: (A) polyphenols derived from natural resources, including tannins, phenolic acids, flavonoids, lignin, lignans, stilbenes, etc.; (B) a first bio-based polymer selected from at least one polymer: (i) a polymer containing multiple amino groups; or (ii) a polymer containing multiple hydroxyl groups; or (iii) a polymer containing both multiple amino groups and multiple hydroxyl groups; for example: cellulose, polyvinyl alcohol, chitosan, gelatin, etc.; (C) a second bio-based polymer selected from at least one polymer: (i) a polymer containing multiple amino groups; or (ii) a polymer containing multiple hydroxyl groups; or (iii) a polymer containing both multiple amino groups and multiple hydroxyl groups; for example: cellulose, polyvinyl alcohol, chitosan, gelatin, etc. The selection criteria for the first and second polymers are: (i) at least one of the first or second polymers contains multiple amino groups for Michael addition with oxidized polyphenols; or (ii) both the first and second polymers contain multiple amino groups for Michael addition with oxidized polyphenols, but they are not the same; or (iii) both the first and second polymers contain multiple hydroxyl groups and multiple amino groups for Michael addition with oxidized polyphenols, but they are not the same. When both the first and second polymers contain amino groups, after Michael addition with oxidized polyphenols, a polymer network is formed by the two different polymers, cross-linked through chemical interactions (i.e., covalent bonds) and physical interactions (i.e., hydrogen bonds, van der Waals forces, electrostatic interactions, π-π stacking, metal-ligand coordination, and polymer chain entanglement). When only one of the first and second polymers contains an amino group, after Michael addition with oxidized polyphenols, a polymer network is formed by the covalently cross-linked polymer containing multiple amino groups, while the other polymer without amino groups physically interacts with the polymer network through hydrogen bonds, electrostatic interactions, and polymer chain entanglement. (D) Metal compounds, including aluminum (III), calcium (II), copper (II), gold (III), silver (I), titanium (IV), zinc (II), etc. (E) Solvent systems, including water and alcohols. The adhesive compositions prepared according to the methods described herein are bio-based, light-colored, and odorless. Substrates used for coating the adhesive compositions include cellulose, keratin, fibroin, minerals, cotton, wool, silk, acetate, acrylics, aramids, olefins, polyesters, rayon, spandex, polyethylene terephthalate (PET), nylon, polyurethane (PU), polypropylene (PP), rubber, leather, wood, glass, metals, ceramics, plastics, etc.

[0037] In one embodiment, the composition comprises: 0.01 to 60 wt% of a polyphenol compound; 0.5 to 90 wt% of a first polymer; 0.5 to 90 wt% of a second polymer; 0.01 to 50 wt% of a metal compound; 1 to 99 wt% of a solvent system; wt% based on the total weight of the composition.

[0038] In one embodiment, the composition is prepared by the following steps: dissolving all components in a solvent system at a temperature of 15°C to 95°C, bubbling in air to provide oxygen for the oxidation of polyphenols, and mixing for 1-5 hours.

[0039] In one embodiment, the pH of the composition is adjusted to and maintained at a pH of 7 to 10, which is favorable for Michael addition. The pH is adjusted using an aqueous solution of sodium hydroxide at a concentration of about 1 M. The mixture is further aerated and mixed for 1–5 hours at a temperature of 15°C to 95°C.

[0040] In one embodiment, the composition is cooled by standing at room temperature. The pH of the composition is adjusted to neutral by adding an aqueous solution of hydrochloric acid with a concentration of about 1 M.

[0041] This invention provides an adhesive for use as a bonding agent, coating, or laminator. In one embodiment, the adhesive comprises the adhesive composition. For immediate use, the adhesive composition is applied to a substrate surface that has undergone mechanical, chemical, or energy pretreatment by allowing it to cool to approximately 15°C to 30°C at room temperature and then using a coater. The bonded, coated, or laminated substrate is cured at a temperature of 30°C to 90°C for at least 10 minutes. For storage, the adhesive composition is transferred to a container. It is allowed to stand at room temperature before the container is sealed.

[0042] This invention also provides a pigment paste comprising the aforementioned binder composition, pigment particles, thickener, chelating agent, surfactant, humectant, defoamer, and hand feel improver. The weight percentage of each pigment paste component depends on the formulation. The pigment paste components are thoroughly mixed to prepare a pigment paste for pigment printing. For immediate use, the prepared pigment paste is loaded into a printing machine. After printing on the substrate, the paste is dried and fixed at a temperature below 100°C. For storage, the prepared pigment paste is transferred to a container. It is allowed to stand at room temperature before sealing the container.

[0043] Adhesive composition component (A) Polyphenols

[0044] In one embodiment, the adhesive composition component (A) is a polyphenol derived from a natural resource.

[0045] As used in this article, the term "polyphenol" refers to an organic molecule with multiple phenolic structures. Polyphenols are extracted from natural resources, such as plant tissues including leaves, bark, flowers, and fruits. Polyphenols contain multiple phenolic units, with high levels of dihydroxyphenyl (catechol) and trihydroxyphenyl (gallic acid). Based on the number and binding structure of the units, they are classified into flavonoids, stilbenes, lignans, and phenolic acids. Tannic acid is one type of polyphenol, with the chemical formula C6H2O. 76 H 52 O 46 Tannic acid is a decagalloyl group (i.e., each molecule has ten galloyl moieties) with a central glucose core to which five digalloyl ester groups are covalently attached. Hydrogen donors (hydrogen in the amine group and hydroxyl group) and acceptors (O in the carbonyl group and N in the amine group) have multiple sources. Furthermore, tannic acid has ten aromatic benzene units for π-π stacking and hydrophobic interactions. Due to the numerous phenolic groups in its structure, tannic acid is a weak acid (pKa of approximately 6). In solvents with pH above pKa, tannic acid is a polyanion (i.e., negatively charged), which can bind to other materials through electrostatic interactions. The lone pair electrons of the phenolic hydroxyl group in tannic acid interact with metal ions such as Al. 3+ Ca 2+ Cu 2+ Au 3+ Ag + Ti 4+ Zn 2+ Coordinate bonds are formed. In the presence of oxygen or an oxidizing agent, the phenolic hydroxyl groups of tannic acid are oxidized to quinones. Quinones can react with the amino groups of polymers (such as chitosan and gelatin) to form covalent bonds through Michael addition, provided that the pH of the solution is adjusted to pH 7 to pH 10.

[0046] Adhesive composition component (B) First bio-based polymer

[0047] In one embodiment, the adhesive composition component (B) is a first bio-based polymer selected from polymers containing multiple amino groups, polymers containing multiple hydroxyl groups, or polymers containing multiple amino groups and multiple hydroxyl groups.

[0048] As used herein, the term "polymer containing multiple amino groups" refers to a polymer molecule having a number of amino groups along its entire hydrocarbon chain. The term "polymer containing multiple hydroxyl groups" refers to a polymer molecule having a number of hydroxyl groups along its entire hydrocarbon chain, such as polyvinyl alcohol made from sugarcane and alcohols. The term "polymer containing both multiple amino groups and multiple hydroxyl groups" refers to a polymer molecule having both multiple amino groups and multiple hydroxyl groups along its entire hydrocarbon chain, such as chitosan and gelatin. The amino groups of the polymer can covalently bind to the quinone moiety of oxidized tannic acid via Michael addition at pH 7 to 10.

[0049] Adhesive composition component (C) Second bio-based polymer

[0050] In one embodiment, the adhesive composition component (C) is a second bio-based polymer selected from polymers containing multiple amino groups, polymers containing multiple hydroxyl groups, or polymers containing multiple amino groups and multiple hydroxyl groups.

[0051] As used herein, the term "polymer containing multiple amino groups" refers to a polymer molecule having a number of amino groups along its entire hydrocarbon chain. The term "polymer containing multiple hydroxyl groups" refers to a polymer molecule having a number of hydroxyl groups along its entire hydrocarbon chain, such as polyvinyl alcohol made from sugarcane and alcohols. The term "polymer containing both multiple amino groups and multiple hydroxyl groups" refers to a polymer molecule having both multiple amino groups and multiple hydroxyl groups along its entire hydrocarbon chain, such as chitosan and gelatin. The amino groups of the polymer can covalently bind to the quinone moiety of oxidized tannins via Michael addition at pH 7 to 10.

[0052] To enable the tannic acid to undergo Michael addition with the polymer, the selection criteria for the first and second polymers are as follows: (i) at least the first or second polymer contains a plurality of amino groups for Michael addition with oxidized polyphenols; or (ii) both the first and second polymers contain a plurality of amino groups for Michael addition with oxidized polyphenols, but they are not the same; or (iii) both the first and second polymers contain a plurality of hydroxyl groups and a plurality of amino groups for Michael addition with oxidized polyphenols, but they are not the same.

[0053] The incorporation of two different polymers can have a synergistic effect on the mechanical properties of the resulting adhesive, such as enhancing adhesive strength and toughness.

[0054] Adhesive composition component (D) Metal compound

[0055] In one embodiment, the adhesive composition component (D) is a metal compound selected from the periodic table, excluding arsenic, beryllium, cadmium, hexavalent chromium, lead, and mercury (note: these are classified as toxic metals on the website of the Occupational Safety and Health Administration of the U.S. Department of Labor).

[0056] When a metal compound is dissolved in an aqueous solvent, it releases metal ions. A coordination complex is formed by the central metal ion and a series of surrounding ligands. The phenolic hydroxyl group of tannic acid provides a lone pair of electrons to bind with metal ions such as aluminum(III), calcium(II), copper(II), gold(III), silver(I), titanium(IV), and zinc(II).

[0057] Adhesive composition component (E) solvent system

[0058] In one embodiment, the adhesive composition component (E) is a solvent system comprising proton solvents such as water and alcohol.

[0059] Other adhesive composition components (A) to (D) are soluble in water and alcohol because components (A) to (C) have hydrophilic functional groups such as hydroxyl and amine, and component (D) is ionic in nature.

[0060] Substrate

[0061] In one embodiment, the substrate for coating the adhesive composition includes cellulose, keratin, fibroin, minerals, cotton, wool, silk, acetate, acrylic, aramid, olefin, polyester, rayon, spandex, polyethylene terephthalate (PET), nylon, polyurethane (PU), polypropylene (PP), rubber, leather, wood, glass, metal, ceramics, plastics, etc.

[0062] Adhesive layer

[0063] In one embodiment, the adhesive layer is formed from the adhesive composition of the present invention as described herein, comprising at least (A) a polyphenol, and (B) a first bio-based polymer selected from i) a polymer containing multiple amino groups, or ii) a polymer containing multiple hydroxyl groups, or iii) a polymer containing multiple amino groups and multiple hydroxyl groups, and (C) a second bio-based polymer selected from i) a polymer containing multiple amino groups, or ii) a polymer containing multiple hydroxyl groups, or iii) a polymer containing multiple amino groups and multiple hydroxyl groups, provided that at least the first polymer or the second polymer contains multiple amino groups for Michael addition with the oxidized polyphenol, and the first polymer and the second polymer are not the same, and (D) a metal compound, excluding compounds of arsenic, beryllium, cadmium, hexavalent chromium, lead, and mercury, and (E) a solvent system selected from proton solvents, including water and alcohols. The adhesive composition is prepared as described herein, including oxidation and Michael addition.

[0064] Products

[0065] In one embodiment, the present invention provides an article comprising at least one component formed from a coated substrate according to any embodiment disclosed herein.

[0066] In one embodiment, the article is a laminated material.

[0067] Non-limiting examples of articles include: i) accessories such as clothing, handbags and belts; ii) furniture decorations such as interior parts for homes, offices and automobiles; iii) household goods such as tablecloths, curtains and display screens; iv) waterproof fabrics, covers and industrial blankets, such as chemically treated fabrics or textiles for industrial or civil engineering applications; v) pressure-sensitive applications such as structural tapes for shoes and wall panel sealing tapes.

[0068] In one embodiment, the article is a pigment-printed product.

[0069] Non-limiting examples of articles include: i) fabrics with pigment printing; ii) paper with pigment printing; iii) metal objects with pigment printing; iv) glass objects with pigment printing; and v) ceramic objects with pigment printing.

[0070] The following non-limiting embodiments are provided to illustrate the invention and are not intended to limit its scope in any way.

[0071] Example 1. Tannic acid / polyvinyl alcohol / gelatin / AlCl3; cotton fabric / cotton fabric

[0072] Tannic acid (0.04 g), polyvinyl alcohol (3.5 g), gelatin (0.8 g), and aluminum chloride hexahydrate (0.3 g) were added to water (16 mL), and the pH was adjusted to 8.5 with 1 M sodium hydroxide solution. The reaction mixture was heated to 80°C and stirred with air bubbled in for 60 minutes, ensuring that the pH was maintained at 8.5. After 1 hour, the reaction mixture was cooled to ambient temperature and the pH was adjusted to neutral with 1 M hydrochloric acid solution. The final solution was then applied to a piece of cotton fabric (woven, plain weave, weight: 134 g / m²). 2 (Thickness: ~0.34 mm). Another piece of cotton fabric was placed over the fabric coated with the adhesive composition. The assembly was pressed down to ensure the adhesive layer thickness was within 0.025 mm. The assembly was then cured at 60°C for 40 minutes. The T-peel strength of the laminated cotton fabric assembly was measured according to the test standard ASTM D1876. The results were compared with commercially available adhesives, and the data are shown in Table 1.

[0073] Example 2. Polyvinyl alcohol / gelatin / AlCl3; cotton fabric / cotton fabric (control)

[0074] Polyvinyl alcohol (3.5 g), gelatin (0.8 g), and aluminum chloride hexahydrate (0.3 g) were added to water (16 mL), and the pH was adjusted to 8.5 with 1 M sodium hydroxide solution. The reaction mixture was heated to 80°C and stirred with air bubbled in for 60 minutes, ensuring the pH was maintained at 8.5. After 1 hour, the reaction mixture was cooled to ambient temperature and the pH was adjusted to neutral with 1 M hydrochloric acid solution. The final solution was then applied to a piece of cotton fabric (woven, plain weave, weight: 134 g / m²). 2(Thickness: ~0.34 mm). Another piece of cotton fabric was placed over the fabric coated with the adhesive composition. The assembly was pressed down to ensure the adhesive layer thickness was within 0.025 mm. The assembly was then cured at 60°C for 40 minutes. The T-peel strength of the laminated cotton fabric assembly was measured according to the test standard ASTM D1876. The results were compared with commercially available adhesives, and the data are shown in Table 1.

[0075] Example 3. Tannic acid / polyvinyl alcohol / gelatin; cotton fabric / cotton fabric (control).

[0076] Tannic acid (0.04 g), polyvinyl alcohol (3.5 g), and gelatin (0.8 g) were added to water (16 mL), and the pH was adjusted to 8.5 with 1 M sodium hydroxide solution. The reaction mixture was heated to 80°C and stirred with air bubbled in for 60 minutes, ensuring the pH was maintained at 8.5. After 1 hour, the reaction mixture was cooled to ambient temperature and the pH was adjusted to neutral with 1 M hydrochloric acid solution. The final solution was then applied to a piece of cotton fabric (woven, plain weave, weight: 134 g / m²). 2 (Thickness: ~0.34 mm). Another piece of cotton fabric was placed over the fabric coated with the adhesive composition. The assembly was pressed down to ensure the adhesive layer thickness was within 0.025 mm. The assembly was then cured at 60°C for 40 minutes. The T-peel strength of the laminated cotton fabric assembly was measured according to the test standard ASTM D1876. The results were compared with commercially available adhesives, and the data are shown in Table 1.

[0077] Example 4. Polyvinyl alcohol / gelatin; cotton fabric / cotton fabric (control)

[0078] Polyvinyl alcohol (3.5 g) and gelatin (0.8 g) were added to water (16 mL), and the pH was adjusted to 8.5 with 1 M sodium hydroxide solution. The reaction mixture was heated to 80°C and stirred with air bubbled in for 60 minutes, ensuring the pH was maintained at 8.5. After 1 hour, the reaction mixture was cooled to ambient temperature and the pH was adjusted to neutral with 1 M hydrochloric acid solution. The final solution was then coated onto a piece of cotton fabric (woven, plain weave, weight: 134 g / m²). 2 (Thickness: ~0.34 mm). Another piece of cotton fabric was placed over the fabric coated with the adhesive composition. The assembly was pressed down to ensure the adhesive layer thickness was within 0.025 mm. The assembly was then cured at 60°C for 40 minutes. The T-peel strength of the laminated cotton fabric assembly was measured according to the test standard ASTM D1876. The results were compared with commercially available adhesives, and the data are shown in Table 1.

[0079] The inventive adhesive compositions in Examples 2, 3, and 4 are controls of the inventive adhesive composition in Example 1. T-peel strength results showed that the T-peel strength of the PVA:gelatin mixture was approximately 550 N / m. Adding tannic acid to the PVA:gelatin composite material resulted in an increase of 120 N / m in T-peel strength. Adding aluminum chloride to the PVA:gelatin composite material resulted in an increase of 430 N / m in T-peel strength. Adding both tannic acid and aluminum chloride to the PVA:gelatin composite material resulted in an increase of approximately 670 N / m in T-peel strength.

[0080] Example 5. Tannic acid / polyvinyl alcohol / gelatin: KCl; cotton fabric / cotton fabric (control).

[0081] Tannic acid (0.04 g), polyvinyl alcohol (3.5 g), gelatin (0.8 g), and potassium chloride (0.3 g) were added to water (16 mL), and the pH was adjusted to 8.5 with 1 M sodium hydroxide solution. The reaction mixture was heated to 80°C and stirred with air bubbled in for 60 minutes, ensuring the pH was maintained at 8.5. After 1 hour, the reaction mixture was cooled to ambient temperature and the pH was adjusted to neutral with 1 M hydrochloric acid solution. The final solution was then applied to a piece of cotton fabric (woven, plain weave, weight: 134 g / m²). 2 A layer of cotton fabric (thickness: ~0.34 mm) was applied. Another piece of cotton fabric was placed over the fabric coated with the adhesive composition. The assembly was pressed to ensure the adhesive layer thickness was within 0.025 mm. The assembly was then cured at 60°C for 40 minutes. The T-peel strength of the laminated cotton fabric assembly was measured according to the test standard ASTM D1876. The results were compared with commercially available adhesives, and the data are shown in Table 1. Compared with the metal compound selected in this invention, potassium ions have a lower charge density, which results in relatively weak coordination bonds between potassium ions and polymers or crosslinking agents. No contribution of potassium to metal-ligand coordination was observed in the peel strength results.

[0082] Example 6. Tannic acid / polyvinyl alcohol / gelatin: CaCl2; cotton fabric / cotton fabric

[0083] Tannic acid (0.04 g), polyvinyl alcohol (3.5 g), gelatin (0.8 g), and calcium chloride (0.3 g) were added to water (16 mL), and the pH was adjusted to 8.5 with 1 M sodium hydroxide solution. The reaction mixture was heated to 80°C and stirred with air bubbled in for 60 minutes, ensuring the pH was maintained at 8.5. After 1 hour, the reaction mixture was cooled to ambient temperature and the pH was adjusted to neutral with 1 M hydrochloric acid solution. The final solution was then applied to a piece of cotton fabric (woven, plain weave, weight: 134 g / m²). 2(Thickness: ~0.34 mm). Another piece of cotton fabric was placed over the fabric coated with the adhesive composition. The assembly was pressed down to ensure the adhesive layer thickness was within 0.025 mm. The assembly was then cured at 60°C for 40 minutes. The T-peel strength of the laminated cotton fabric assembly was measured according to the test standard ASTM D1876. The results were compared with commercially available adhesives, and the data are shown in Table 1.

[0084] Example 7. Tannic acid / polyvinyl alcohol / gelatin: ZnCl2; cotton fabric / cotton fabric

[0085] Tannic acid (0.04 g), polyvinyl alcohol (3.5 g), gelatin (0.8 g), and zinc chloride (0.3 g) were added to water (16 mL), and the pH was adjusted to 8.5 with 1 M sodium hydroxide solution. The reaction mixture was heated to 80°C and stirred with air bubbled in for 60 minutes, ensuring the pH was maintained at 8.5. After 1 hour, the reaction mixture was cooled to ambient temperature and the pH was adjusted to neutral with 1 M hydrochloric acid solution. The final solution was then applied to a piece of cotton fabric (woven, plain weave, weight: 134 g / m²). 2 (Thickness: ~0.34 mm). Another piece of cotton fabric was placed over the fabric coated with the adhesive composition. The assembly was pressed down to ensure the adhesive layer thickness was within 0.025 mm. The assembly was then cured at 60°C for 40 minutes. The T-peel strength of the laminated cotton fabric assembly was measured according to the test standard ASTM D1876. The results were compared with commercially available adhesives, and the data are shown in Table 1.

[0086] Example 8. Tannic acid / polyvinyl alcohol / gelatin: NaCl; cotton fabric / cotton fabric

[0087] Tannic acid (0.04 g), polyvinyl alcohol (3.5 g), gelatin (0.8 g), and sodium chloride (0.3 g) were added to water (16 mL), and the pH was adjusted to 8.5 with 1 M sodium hydroxide solution. The reaction mixture was heated to 80°C and stirred with air bubbled in for 60 minutes, ensuring that the pH was maintained at 8.5. After 1 hour, the reaction mixture was cooled to ambient temperature and the pH was adjusted to neutral with 1 M hydrochloric acid solution. The final solution was then applied to a piece of cotton fabric (woven, plain weave, weight: 134 g / m²). 2 A layer of cotton fabric (thickness: ~0.34 mm) was applied. Another piece of cotton fabric was placed over the fabric coated with the adhesive composition. The assembly was pressed down to ensure the adhesive layer thickness was within 0.025 mm. The assembly was then cured at 60°C for 40 minutes. The T-peel strength of the laminated cotton fabric assembly was measured according to the test standard ASTM D1876. The results were compared with commercially available adhesives, and the data are shown in Table 1.

[0088] Example 9. Tannic acid / polyvinyl alcohol / gelatin: AlCl3; Nylon fabric / nylon fabric

[0089] Tannic acid (0.04 g), polyvinyl alcohol (3.5 g), gelatin (0.8 g), and aluminum chloride hexahydrate (0.3 g) were added to water (16 mL), and the pH was adjusted to 8.5 with 1 M sodium hydroxide solution. The reaction mixture was heated to 80°C and stirred with air bubbled in for 60 minutes, ensuring that the pH was maintained at 8.5. After 1 hour, the reaction mixture was cooled to ambient temperature and the pH was adjusted to neutral with 1 M hydrochloric acid solution. The final solution was then applied to a piece of nylon fabric (woven, plain weave, weight: 134 g / m²). 2 A layer of nylon fabric (thickness: ~0.34 mm) was applied. Another piece of nylon fabric was placed over the fabric coated with the adhesive composition. The assembly was pressed down to ensure the adhesive layer thickness was within 0.025 mm. The assembly was then cured at 60°C for 40 minutes. The T-peel strength of the laminated cotton fabric assembly was measured according to the test standard ASTM D1876. The results were compared with commercially available adhesives, and the data are shown in Table 1.

[0090] Table 1: Comparison of T-peel strength between the adhesive composition of the present invention and commercially available adhesives

[0091] Effect of accelerated aging on T-peel strength

[0092] Another set of test specimens for Example 1 (tannic acid / PVA / gelatin / AlCl3; cotton fabric / cotton fabric) underwent accelerated aging for 48 hours at 57°C and 95% RH before undergoing the ASTM D1876 T-peel strength test. The test results are shown in Table 2. Using an independent samples t-test to compare the two sets of data, the p-value for homogeneity of variance was 0.803 (p > 0.001), indicating that the variance of the T-peel strength of the aged samples was not significantly different from that of the samples under standard conditions.

[0093] Table 2: ASTM D1876 T-peel strength of cotton fabrics bonded with tannin / PVA / gelatin / AlCl3 after accelerated aging and without accelerated aging.

Claims

1. A bio-based adhesive composition comprising: a. 0.01 to 60 wt.% polyphenols; b. 0.5 to 90 wt.% of a first bio-based polymer comprising a plurality of amino or hydroxyl groups as a first Michael donor for a first Michael addition reaction with a first Michael acceptor formed by oxidation of the polyphenol; c. 0.5 to 90 wt.% of a second bio-based polymer; d. 0.01 to 50 wt.% of a metal compound selected from aluminum(III), calcium(II), copper(II), gold(III), silver(I), titanium(IV), sodium(I), and zinc(II) compounds; and e. 1 to 99 wt.% proton solvents; The bio-based adhesive composition can be adjusted to conditions that form a transparent polymer network crosslinked by covalent and non-covalent interactions.

2. The bio-based adhesive composition according to claim 1, wherein the first Michael donor comprises both amino and hydroxyl groups.

3. The bio-based adhesive composition of claim 2, wherein the second bio-based polymer comprises a plurality of amino or hydroxyl groups as a second Michael donor for a second Michael addition reaction with a second Michael acceptor formed by oxidation of the polyphenol.

4. The bio-based adhesive composition of claim 3, wherein the second Michael donor is an amino or hydroxyl group different from the first Michael donor.

5. The bio-based adhesive composition according to claim 1, wherein: a. The polyphenols include one or more of tannic acid, tannin, phenolic acid, flavonoids, lignin, lignans, or stilbene compounds; b. The first or second bio-based polymer comprises one or more of cellulose, polyvinyl alcohol, chitosan, or gelatin; or c. The proton solvent includes water or alcohol.

6. The bio-based adhesive composition of claim 1, wherein the conditions include dissolving the bio-based adhesive composition at a temperature of 15 to 95°C while oxidizing the polyphenols.

7. The bio-based adhesive composition of claim 6, wherein the conditions further include adjusting and maintaining a pH suitable for the first or second Michael addition reaction.

8. The bio-based adhesive composition of claim 7, wherein the conditions further include adjusting the pH to neutral and cooling to room temperature.

9. The bio-based adhesive composition according to claim 1, wherein the bio-based adhesive composition is a composition selected from the group consisting of: i. Tannic acid, polyvinyl alcohol, gelatin, aluminum chloride hexahydrate, and water; ii. Tannic acid, polyvinyl alcohol, gelatin, calcium chloride, and water; iii. Tannic acid, polyvinyl alcohol, gelatin, zinc chloride, and water; and iv. Tannic acid, polyvinyl alcohol, gelatin, sodium chloride, and water.

10. An article comprising a substrate coated with the bio-based adhesive composition of claim 1.

11. The article of claim 10, wherein the substrate comprises a synthetic or natural material.

12. A method for preparing a bio-based adhesive, comprising the following steps: a. A bio-based adhesive composition comprising: i. 0.01 to 60 wt.% polyphenols; ii. 0.5 to 90 wt.% of a first bio-based polymer comprising a plurality of first Michael donors for a first Michael addition reaction with a first Michael acceptor formed by oxidation of the polyphenol; iii. 0.5 to 90 wt.% of a second bio-based polymer; iv. 0.01 to 50 wt.% of metal compounds; and v. 1 to 99 wt.% proton solvent; b. Dissolve the bio-based adhesive composition at 15 to 95°C and oxidize the polyphenols to form a first solution; c. Adjust the pH of the first solution to a level favorable for the first Michael addition reaction to form a second solution; as well as d. Adjust the second solution to a suitable pH value to form the bio-based adhesive.

13. The method of claim 12, wherein the second bio-based polymer comprises a plurality of second Michael donors for a second Michael addition reaction with a second Michael acceptor formed by oxidation of the polyphenol, and step (c) further comprises adjusting the first solution to a pH favorable to the second Michael addition reaction to form the second solution.

14. The method of claim 12, wherein the bio-based adhesive composition is a composition selected from the group consisting of: i. Tannic acid, polyvinyl alcohol, gelatin, aluminum chloride hexahydrate, and water; ii. Tannic acid, polyvinyl alcohol, gelatin, calcium chloride, and water; iii. Tannic acid, polyvinyl alcohol, gelatin, zinc chloride, and water; and iv. Tannic acid, polyvinyl alcohol, gelatin, sodium chloride, and water.

15. The method of claim 12, further comprising one or more of the following steps: a. The temperature in step (b) is 80 to 90°C; b. The oxidation in step (b) includes bubbling air into the first solution; c. The pH value of step (c) is between pH 7 and 10; d. Step (c) includes further oxidizing the polyphenol; and e. The appropriate pH value for step (d) is neutral.

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