Water-based adhesive

Abstract

The present disclosure relates to an adhesive kit comprising a first emulsion and a second emulsion configured to reversibly adhere to each other. The present disclosure also provides methods for using the kit. The present disclosure also provides an aqueous emulsion comprising positively or negatively charged particles dispersed in an aqueous phase, the particles comprising a hydrophobic polymer.

Description

[Technical Field]

[0001] The present invention relates to an adhesive kit comprising a first emulsion and a second emulsion configured to reversibly adhere to each other. The present invention also provides a method for using the kit. The present invention also provides an aqueous emulsion comprising positively or negatively charged particles dispersed in an aqueous phase, the particles comprising a hydrophobic polymer. [Background technology]

[0002] Organic solvent-free adhesives are more environmentally friendly than volatile organic compound (VOC)-based solvents and are of particular interest in laminating textiles, industrial products, foams, and fabrics. The increased use of solvent-free adhesives is also driven by the need for increased sustainability and the need to reduce VOCs due to regulatory and customer pressure. This has led to several new generations of adhesives and sealants. Examples of these include fast-cure epoxy adhesives and polyurethane-reactive (PUR) adhesives, UV- and light-cure acrylic adhesives, and cyanoacrylate-based adhesives.

[0003] Demand for water-based adhesives has grown over the past two decades, primarily from the packaging and processing industries. The type of packaging adhesive used depends on factors such as the materials being joined, the manufacturing equipment, and the end-use bonding requirements. Such adhesives typically contain a polymer, which provides the adhesive's cohesive strength (i.e., internal strength). The required penetration is achieved by dissolving or dispersing the polymer in water, or by melting it into a liquid form. The adhesive is returned to a solid state by removing the water through absorption or evaporation, or by cooling the melt.

[0004] Although adhesives themselves do not usually pose major environmental problems, global efforts to address the environmental issue are largely focused on recycling post-consumer materials. These post-consumer materials may contain components (e.g., labels) that are held in place by adhesives. Such labels are often difficult to remove from bottles, complicating the recycling process. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, there is a significant need in the art for reversible water-based adhesives, and there is also a need for the development of environmentally sustainable adhesives. [Means for solving the problem]

[0006] According to a first aspect of the present invention, there is provided an adhesive kit comprising: a first aqueous emulsion comprising particles dispersed in a first aqueous phase, the particles comprising a first hydrophobic polymer and the particles of the first aqueous emulsion being positively charged; and a second aqueous emulsion comprising particles dispersed in a second aqueous phase, the particles comprising a second hydrophobic polymer and the particles of the second aqueous emulsion being negatively charged. Typically, the first and second aqueous emulsions are configured to reversibly adhere to each other.

[0007] The adhesive kit of the present invention achieves several advantages over prior art adhesives.

[0008] The adhesive kit uses two aqueous emulsions that can be coated onto opposing surfaces to reversibly bond the surfaces together. In particular, the inventors have discovered that a first surface coated with a first aqueous emulsion containing a hydrophobic polymer and a positively charged polymer can adhere to a second surface coated with a second aqueous emulsion containing a hydrophobic polymer and a negatively charged polymer, forming a bonded interface. While not wishing to be bound by theory, it is believed that electrostatic attraction between the positively charged polymer and the negatively charged polymer promotes adhesion. The two components adhere to each other in water and remain bonded even after the adhesive dries. Typically, moisture does not impair the adhesion between the two components.

[0009] Furthermore, adhesion can be reversed by changing the local pH at the bonding interface. Without wishing to be bound by theory, it is believed that changing the local pH neutralizes either the positively charged polymer in the first aqueous emulsion or the negatively charged polymer in the second aqueous emulsion. For example, when the pH decreases, the negatively charged polymer is protonated, but the charge of the positively charged polymer remains unchanged. Conversely, when the pH increases, the positively charged polymer can be deprotonated, but the charge of the negatively charged polymer remains unchanged. As a result, in both pH-changing situations, the electrostatic interaction between the particles of the first aqueous emulsion and the particles of the second aqueous emulsion is eliminated, thereby reversing the adhesion between the first and second surfaces. Therefore, the adhesive kit of the present invention provides easy and effective reversibility without extensive chemical processing, which is particularly advantageous in extensive recycling processes.

[0010] Additionally, the adhesive kit of the present invention is solvent-free and uses commodity materials, providing an inexpensive, scalable, and environmentally friendly system.

[0011] In a second aspect of the present invention, there is provided a method of adhering two surfaces together using the adhesive kit of the first aspect, the method comprising the steps of: coating a first surface with a first aqueous emulsion; coating a second surface with a second aqueous emulsion; and contacting the first surface coated with the first aqueous emulsion with the second surface coated with the second aqueous emulsion to adhere the first surface and the second surface to one another at a bonding interface.

[0012] In a third aspect of the present invention there is provided a system obtained or obtainable by the method of the second aspect, the system comprising a first surface and a second surface, the first surface being adhered to the second surface.

[0013] In a fourth aspect of the present invention, there is provided a method of producing the adhesive kit of the first aspect, the method comprising forming a first aqueous emulsion and a second aqueous emulsion.

[0014] In a fifth aspect of the present invention, there is provided an aqueous emulsion (hereinafter sometimes referred to as a first aqueous emulsion) comprising particles dispersed in an aqueous phase (hereinafter sometimes referred to as a first aqueous phase), wherein the particles of the aqueous emulsion comprise a hydrophobic polymer (hereinafter sometimes referred to as a first hydrophobic polymer), and the particles of the aqueous emulsion are positively charged.

[0015] In a sixth aspect of the present invention, there is provided an aqueous emulsion (hereinafter sometimes referred to as second aqueous emulsion) comprising particles dispersed in an aqueous phase (hereinafter sometimes referred to as second aqueous phase), wherein the particles of the aqueous emulsion comprise a hydrophobic polymer (hereinafter sometimes referred to as second hydrophobic polymer), and the particles of the aqueous emulsion are negatively charged.

[0016] In a seventh aspect of the present invention, there is provided a method of adhering two surfaces together using the emulsion of the fifth or sixth aspect, the method comprising the steps of coating a first surface and / or a second surface with the aqueous emulsion of the fifth or sixth aspect; and contacting the first and second surfaces so as to adhere the first and second surfaces together at a bonding interface.

[0017] The adhesives formed in the methods or from the products of the present invention are flexible when bonded, unlike some prior art adhesives which can impart stiffness to any flexible substrates they are used to bond. Furthermore, because the adhesives of the present invention are clear and remain clear after bonding, the final bonded product is more aesthetically pleasing than some known adhesive systems.

[0018] Adhesive kits and water-based emulsions The first hydrophobic polymer may be polystyrene, polyacrylate, polymethacrylate, polyvinyl, polydiene, or a mixture / copolymer thereof. The first hydrophobic polymer may be selected from polystyrene, poly(butyl acrylate), poly(styrene-butyl acrylate) copolymer, or polybutadiene. The first hydrophobic polymer may be polystyrene, polyacrylate, polymethacrylate, or polyvinyl, or a mixture / copolymer thereof. The first hydrophobic polymer may be selected from polystyrene, poly(butyl acrylate), or poly(styrene-butyl acrylate) copolymer. The first hydrophobic polymer may be poly(styrene-butyl acrylate) copolymer.

[0019] When the first hydrophobic polymer is a poly(styrene-butyl acrylate) copolymer, the copolymer may comprise styrene and butyl acrylate in a weight ratio ranging from 3:1 to 0.01:1, such as a weight ratio ranging from 1.5:1 to 1:1.5. The copolymer may comprise styrene and butyl acrylate in a weight ratio of about 1:1.5.

[0020] The particles of the first aqueous emulsion may further comprise a positively charged polymer (e.g., a polycation). The positively charged polymer (e.g., a polycation) may be associated with the first hydrophobic polymer. For example, the positively charged polymer (e.g., a polycation) may be associated with the first hydrophobic polymer through hydrophobic interactions, electrostatic interactions, or covalent interactions.

[0021] The components of the particle can be arranged and selected so that positively charged groups (e.g., amino groups) are located on the surface of the particle. The components of the particle can be arranged and selected so that the concentration of positively charged groups (e.g., amino groups) on the surface of the particle is higher than the concentration in the interior of the particle. Thus, the hydrophobic polymer can be located in the interior of the particle and the positively charged polymer can be located on the exterior of the particle.

[0022] A positively charged polymer may be a polymeric species that contains one or more positively charged groups. A positively charged polymer may be a polymeric species that contains multiple positively charged groups.

[0023] In certain embodiments, the first aqueous emulsion has a pH of about 5 to about 8. Preferably, the first aqueous emulsion has a pH of about 5. The positively charged polymer (e.g., a polycation) may contain one or more basic groups that are protonated to form cations at the pH of the first aqueous emulsion, for example, in the pH range of about 5 to about 8. The positively charged polymer (e.g., a polycation) may contain multiple basic groups that are protonated to form cations at the pH of the first aqueous emulsion, for example, in the pH range of about 5 to about 8. The positively charged polymer (e.g., a polycation) may contain one or more amino groups. The positively charged polymer (e.g., a polycation) may contain multiple amino groups. The amino groups may be primary amino groups, secondary amino groups, or tertiary amino groups. The amino groups may be primary amino groups.

[0024] The positively charged polymer may be selected from the group including chitosan, polyaminoacrylate, polyaminomethacrylate, polyallylamine, and polyethyleneimine. The positively charged polymer may be selected from chitosan, poly[2-(dimethylamino)ethyl acrylate], poly[2-(dimethylamino)ethyl methacrylate], and polyethyleneimine. The positively charged polymer may be chitosan.

[0025] The particles of the first aqueous emulsion can be present in an amount ranging from about 20% to about 40% by weight of the first aqueous emulsion, and can be present in an amount of about 30% by weight of the first aqueous emulsion.

[0026] The particles of the first aqueous emulsion may comprise a hydrophobic polymer and a positively charged polymer (eg, a polycation) in a ratio ranging from about 20:1 to about 60:1 by weight of the first aqueous emulsion.

[0027] The first aqueous emulsion may have a low shear viscosity in the range of about 25 to about 100 Pa·s. The first aqueous emulsion may have a high shear viscosity in the range of about 50 to about 150 mPa·s.

[0028] The second hydrophobic polymer may be polystyrene, polyacrylate, polymethacrylate, polyvinyl, polydiene, or a mixture / copolymer thereof. The second hydrophobic polymer may be selected from polystyrene, poly(butyl acrylate), poly(styrene-butyl acrylate) copolymer, or polybutadiene. The second hydrophobic polymer may be polystyrene, polyacrylate, polymethacrylate, or polyvinyl, or a mixture / copolymer thereof. The second hydrophobic polymer may be selected from polystyrene, poly(butyl acrylate), or poly(styrene-butyl acrylate) copolymer. The second hydrophobic polymer may be poly(styrene-butyl acrylate) copolymer.

[0029] When the second hydrophobic polymer is a poly(styrene-butyl acrylate) copolymer, the copolymer may comprise styrene and butyl acrylate in a weight ratio ranging from 3:1 to 0.01:1, such as a weight ratio ranging from 1.5:1 to 1:1.5. The copolymer may comprise styrene and butyl acrylate in a weight ratio of about 1:1.5.

[0030] The first hydrophobic polymer and the second hydrophobic polymer may be the same type, for example, both the first hydrophobic polymer and the second hydrophobic polymer may be poly(styrene-butyl acrylate) copolymer.

[0031] The particles of the second aqueous emulsion may further comprise a negatively charged polymer (e.g., a polyanion). The negatively charged polymer (e.g., a polyanion) may be associated with the second hydrophobic polymer. For example, the negatively charged polymer (e.g., a polyanion) may be associated with the second hydrophobic polymer through hydrophobic interactions, electrostatic interactions, or covalent interactions.

[0032] The negatively charged polymer may be a polymeric species having one or more negatively charged groups. The negatively charged polymer may be a polymeric species having multiple negatively charged groups.

[0033] The components of the particle can be arranged and selected so that the negatively charged groups (e.g., carboxylate groups) are located on the surface of the particle. The components of the particle can be arranged and selected so that the concentration of negatively charged groups (e.g., carboxylate groups) on the surface of the particle is higher than the concentration in the interior of the particle. Thus, the hydrophobic polymer can be located in the interior of the particle and the negatively charged polymer can be located on the exterior of the particle.

[0034] In certain embodiments, the second aqueous emulsion has a pH of about 5 to about 8, optionally about 5. The negatively charged polymer (e.g., a polyanion) may contain one or more groups that deprotonate to form anions at the pH of the second aqueous emulsion, for example, a pH range of about 5 to about 8. The negatively charged polymer (e.g., a polyanion) may contain multiple groups that deprotonate to form anions at the pH of the second aqueous emulsion, for example, a pH range of about 5 to about 8. The negatively charged polymer (e.g., a polyanion) may contain carboxylate, sulfonate, phosphonate, or boronate groups. The negatively charged polymer (e.g., a polyanion) may contain one or more carboxylate groups. The negatively charged polymer (e.g., a polyanion) may contain multiple carboxylate groups.

[0035] The negatively charged polymer (e.g., polyanion) may be selected from the group including polyacrylic acid, acidic biopolymers, polysulfonic acid, and polymaleic acid. The negatively charged polymer (e.g., polyanion) may be selected from poly(acrylic acid), alginate, carboxymethylcellulose, xanthan gum, gum arabic, carrageenan, poly(2-acrylamido-2-methylpropanesulfonic acid), poly(methacrylic acid), poly(maleic acid), and poly(vinylsulfonic acid). The negatively charged polymer (e.g., polyanion) is poly(acrylic acid).

[0036] The particles of the second aqueous emulsion can be present in an amount ranging from about 20% to about 40% by weight of the second aqueous emulsion.The particles of the second aqueous emulsion can be present in an amount of about 30% by weight of the second aqueous emulsion.

[0037] The particles of the second aqueous emulsion may comprise a hydrophobic polymer and a negatively charged polymer (eg, a polyanion) in a ratio ranging from about 20:1 to about 60:1 by weight of the second aqueous emulsion.

[0038] The second aqueous emulsion may have a low shear viscosity in the range of about 25 to about 100 Pa·s. The second aqueous emulsion may have a high shear viscosity in the range of about 50 to about 150 mPa·s.

[0039] The low shear viscosity of the first aqueous emulsion may be approximately equal to the low shear viscosity of the second aqueous emulsion.

[0040] The high shear viscosity of the first aqueous emulsion may be approximately equal to the high shear viscosity of the second aqueous emulsion.

[0041] The first hydrophobic polymer has a glass transition temperature (T) of less than about 50°C, less than about 25°C, or less than about 20°C. g The first hydrophobic polymer may have a glass transition temperature (T) of greater than about -50°C. g The first hydrophobic polymer may have a glass transition temperature (T) of about -50°C to about 50°C, about -50°C to about 25°C, about -50°C to about 20°C, about -25°C to about 20°C, about 0°C to about 20°C, or about 10°C to about 20°C. g ) may be included.

[0042] The second hydrophobic polymer has a glass transition temperature (T) of less than about 50° C., less than about 25° C., or less than about 20° C. g The second hydrophobic polymer may have a glass transition temperature (T) of greater than about -50°C. g The second hydrophobic polymer may have a glass transition temperature (T) of about -50°C to about 50°C, about -50°C to about 25°C, about -50°C to about 20°C, about -25°C to about 20°C, about 0°C to about 20°C, or about 10°C to about 20°C. g ) may be included.

[0043] The particles of the second aqueous emulsion may further comprise one or more additives. The one or more additives may each comprise one or more sulfate groups. In an embodiment, the particles of the second aqueous emulsion each comprise one additive. In an embodiment, the particles of the second aqueous emulsion each comprise an additive comprising one or more sulfate groups.

[0044] Each additive may be an anionic surfactant or a cationic surfactant.

[0045] Each additive may be an anionic surfactant. For example, the additive may be an anionic surfactant selected from alkyl sulfates, alkyl ether sulfates, and alkyl sulfonates. Preferably, the additive is sodium dodecyl sulfate.

[0046] Each additive may be a cationic surfactant. For example, the additive may be a cationic surfactant selected from alkylammonium halides or other alkylammonium salts. Specific examples of cationic surfactants include triethylamine hydrochloride, octenidine dihydrochloride, Adogen, cetrimonium bromide, cetylpyridinium chloride, benzethonium chloride, and dimethyldioctadecylammonium chloride.

[0047] Preferably, the difference in pH between the first and second aqueous emulsions is not more than 2. The difference in pH between the first and second aqueous emulsions may be not more than 1. The difference in pH between the first and second aqueous emulsions is not more than 0.5. Both the first and second aqueous emulsions have a pH in the range of about 5 to about 8, optionally about 5.

[0048] The particles of the first aqueous emulsion may have a size in the range of about 0.1 to about 200 μm, optionally in the range of about 80 to about 200 μm.The particles of the first aqueous emulsion may have a size in the range of about 10 nm to about 20 μm, optionally in the range of about 20 nm to about 10 μm.

[0049] The particles of the second aqueous emulsion may have a size in the range of about 0.1 to about 200 μm, optionally in the range of about 80 to about 200 μm.The particles of the second aqueous emulsion may have a size in the range of about 10 nm to about 20 μm, optionally in the range of about 20 nm to about 10 μm.

[0050] The particles of the first aqueous emulsion and the particles of the second aqueous emulsion may have a size in the range of about 0.1 to about 200 μm, optionally in the range of about 80 to about 200 μm.The particles of the first aqueous emulsion and the particles of the second aqueous emulsion may have a size in the range of about 10 nm to about 20 μm, optionally in the range of about 20 nm to about 10 μm.

[0051] Particle size can be determined by dynamic light scattering. This process involves irradiating particles with a laser and analyzing the intensity fluctuations of the scattered light to measure the Brownian motion of the particles and determine particle size. A device that measures dynamic light scattering (e.g., a Zetasizer system) determines the average particle size and polydispersity index from a sample, typically generating these in the form of a particle size distribution curve or histogram. To determine the particle size in the first or second aqueous emulsion, a sample of the first or second aqueous emulsion can be diluted with deionized water and placed in a dynamic light scattering device.

[0052] The first and second aqueous emulsions are configured to reversibly adhere to each other, and the particles of the first and second aqueous emulsions can interact with each other via ionic interactions between the positively charged polymers of the first and second aqueous emulsion particles and the negatively charged polymers of the second aqueous emulsion particles.

[0053] How to use the adhesive kit In a second aspect, there is provided a method of using the adhesive kit of the first aspect, comprising the steps of: coating a first surface with a first aqueous emulsion; coating a second surface with a second aqueous emulsion; and contacting the first surface coated with the first aqueous emulsion with a second surface coated with the second aqueous emulsion to adhere the first surface and the second surface to one another at a bonding interface.

[0054] The method may further include changing the pH of the first and second surfaces at the bonding interface to separate the first and second surfaces from each other. For example, the method may include decreasing the pH of the first and second surfaces at the bonding interface to separate the first and second surfaces from each other. Alternatively, the method may include increasing the pH of the first and second surfaces at the bonding interface to separate the first and second surfaces from each other.

[0055] The step of separating the first and second surfaces from one another at the bonding interface may include treating the first and second surfaces from one another at the bonding interface with an acidic solution having a pH of less than about 5, less than about 4, less than about 3, less than about 2, or less than about 1. Alternatively, the step of separating the first and second surfaces from one another at the bonding interface may include treating the first and second surfaces from one another at the bonding interface with an alkaline solution having a pH of greater than about 9, greater than about 10, greater than about 11, greater than about 12, or greater than about 13. The separating step may be accomplished by submerging or immersing the adhesive-containing product in the acidic or alkaline solution.

[0056] The step of coating the first surface and the second surface comprises coating the first aqueous emulsion and the second aqueous emulsion at about 1 mg / cm 2 ~about 100mg / cm 2 The step of coating the first surface and the second surface may include applying the first aqueous emulsion and the second aqueous emulsion to the first surface and the second surface at a weight / area ratio in the range of about 10 mg / cm. 2 ~about 100mg / cm 2 The step of coating the first surface and the second surface may include applying the first aqueous emulsion and the second aqueous emulsion to the first surface and the second surface at a weight / area ratio in the range of about 20 mg / cm. 2 ~about 30mg / cm 2 to the first surface and the second surface at a mass / area ratio in the range of

[0057] The first surface and the second surface may be independently selected from polypropylene (PP), poly(ethylene terephthalate) (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), polyvinyl chloride (PVC), polystyrene (PS), melamine, cellulose acetate, unspecified polymeric resins, metals (e.g., steel, copper), ceramics, silicon, wood, glass, and printed circuit boards. The first surface and the second surface may be independently selected from polypropylene, poly(ethylene terephthalate) (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), cellulose acetate, steel, copper, wood, glass, and printed circuit boards. The first and second surfaces may be independently selected from polypropylene, poly(ethylene terephthalate), HDPE, LDPE, PVC, PS, melamine, unspecified polymer resins, and glass. The first and second surfaces may be independently selected from polypropylene (PP) and poly(ethylene terephthalate) (PET).

[0058] At least one of the first surface and the second surface can form a part of a flexible substrate. The first surface can form a part of a flexible substrate. The second surface can form a part of a flexible substrate. Each of the first surface and the second surface can form a part of a flexible substrate.

[0059] Coating the surface can be accomplished using a brush or applicator. Coating the surface may include spray coating.

[0060] The method may be a method of labelling a bottle, wherein either the first surface or the second surface is an exterior surface of the bottle, and one of the first surface or the second surface is a label.

[0061] After the step of separating the first and second surfaces from each other, the method may further include the step of cleaning the first and / or second surfaces to remove excess adhesive. Thus, after using the adhesive kit of the present disclosure, the parts having the first and / or second surfaces can be recycled.

[0062] Cleaning the first surface and / or the second surface may comprise treating the first surface and / or the second surface with an organic solvent.

[0063] The organic solvent may be selected from acetone and turpentine.

[0064] Method for manufacturing adhesive kits In a third aspect, there is provided a method of making the adhesive kit of the first aspect, comprising forming a first aqueous emulsion and a second aqueous emulsion.

[0065] The method may include stirring one or more first hydrophobic monomers with a positively charged polymer to form an emulsion, and polymerizing the emulsion in water to form a first aqueous emulsion.

[0066] The step of forming an emulsion from the one or more first hydrophobic monomers and the positively charged polymer may be carried out for at least 5 minutes, optionally at least 10 minutes.

[0067] The step of polymerizing the emulsion to form the first aqueous emulsion may involve free radical emulsion polymerization. Therefore, this step may include the addition of a free radical initiator. The free radical initiator may be a persulfate, a peroxide, or an aliphatic azo compound. For example, the free radical initiator may be selected from potassium persulfate (KPS) and azobisisobutyronitrile (AIBN).

[0068] The step of polymerizing the emulsion to form the first aqueous emulsion may be carried out at a temperature of at least 70°C.

[0069] The step of polymerizing the emulsion to form the first aqueous emulsion may be carried out for at least 4 hours.

[0070] The one or more first hydrophobic monomers may be selected from styrene (e.g., butyl styrene), acrylates (e.g., butyl acrylate), methacrylates (e.g., butyl methacrylate, ethylhexyl methacrylate, ethylhexyl methacrylate), vinyls (e.g., vinyl acetate, vinyl laurate), acrylated soybean oil, divinylbenzene. The one or more first hydrophobic monomers may be selected from styrene and butyl acrylate.

[0071] The method may include stirring one or more second hydrophobic monomers with an additive to form an emulsion, polymerizing the emulsion in water to form an intermediate aqueous emulsion, adding a negatively charged monomer to the intermediate aqueous emulsion, and polymerizing the mixture of the intermediate aqueous emulsion and the negatively charged monomer in water to form a second aqueous emulsion.

[0072] The step of stirring the one or more second hydrophobic monomers with the additive to form an emulsion may be carried out for at least 5 minutes.

[0073] The step of polymerizing the emulsion to form the intermediate aqueous emulsion may involve free radical emulsion polymerization. Therefore, this step may include the addition of a free radical initiator. The free radical initiator may be a persulfate, a peroxide, or an aliphatic azo compound. For example, the free radical initiator may be selected from potassium persulfate (KPS) and azobisisobutyronitrile (AIBN).

[0074] The step of polymerizing the emulsion to form the intermediate aqueous emulsion may be carried out at a temperature of at least 70°C.

[0075] The step of polymerizing the emulsion to form the intermediate aqueous emulsion may be carried out for at least 2 hours.

[0076] The step of adding the negatively charged monomer to the intermediate aqueous emulsion may further include the step of adding a free radical initiator.

[0077] The step of polymerizing the mixture of the intermediate aqueous emulsion and the negatively charged monomer in water to form the second aqueous emulsion may be carried out at a temperature of at least 70°C.

[0078] The step of polymerizing the mixture of the intermediate aqueous emulsion and the negatively charged monomer in water to form the second aqueous emulsion can be carried out for at least 2 hours.

[0079] The one or more second hydrophobic monomers may be selected from styrene (e.g., butyl styrene), acrylates (e.g., butyl acrylate), methacrylates (e.g., butyl methacrylate, ethylhexyl methacrylate, ethylhexyl methacrylate), vinyls (e.g., vinyl acetate, vinyl laurate), acrylated soybean oil, divinylbenzene. The one or more hydrophobic monomers may be selected from styrene and butyl acrylate.

[0080] The positively charged polymer, the negatively charged polymer and the additive may be as described in any of the embodiments in the specification relating to the first aspect of the invention.

[0081] How to glue two surfaces together A seventh aspect of the invention is a method of adhering two surfaces together, comprising the steps of: coating the first surface and / or the second surface with an aqueous emulsion; contacting the first surface with the second surface to adhere the first surface and the second surface to one another at a bonding interface; The aqueous emulsion is an aqueous emulsion comprising particles dispersed in an aqueous phase, wherein the particles of the aqueous emulsion comprise a hydrophobic polymer, and wherein the particles of the aqueous emulsion are positively charged; An aqueous emulsion comprising particles dispersed in an aqueous phase, the particles of the aqueous emulsion comprising a hydrophobic polymer, the particles of the aqueous emulsion being negatively charged. The method is selected from the following:

[0082] The present inventors have surprisingly discovered that each emulsion of the present invention is a strong, irreversible adhesive. In particular, these adhesives have been shown to be effective adhesives for polypropylene.

[0083] The method may include coating only the first surface with the aqueous emulsion. The method may include coating only the second surface with the aqueous emulsion. The method may include coating both the first surface and the second surface with the aqueous emulsion.

[0084] Coating the surface or surfaces may be accomplished using a brush or applicator. Coating the surface or surfaces may include spray coating.

[0085] The step of coating the first surface and the second surface may comprise applying an aqueous emulsion at a concentration of about 1 mg / cm 2 ~about 100mg / cm 2 The step of coating the first surface and / or the second surface may include applying the aqueous emulsion to the first surface and / or the second surface at a weight / area ratio in the range of about 20 mg / cm. 2 ~about 30mg / cm 2 to the first surface and / or the second surface at a mass / area ratio in the range of

[0086] The first surface and the second surface may be independently selected from polypropylene (PP), poly(ethylene terephthalate) (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), polyvinyl chloride (PVC), polystyrene (PS), melamine, cellulose acetate, unspecified polymeric resins, metals (e.g., steel, copper), ceramics, silicon, wood, glass, and printed circuit boards. The first surface and the second surface may be independently selected from polypropylene, poly(ethylene terephthalate), HDPE, LDPE, PVC, PS, melamine, cellulose acetate, unspecified polymeric resins, metals, ceramics, silicon, and glass. The first surface and the second surface may be independently selected from polypropylene (PP), poly(ethylene terephthalate) (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), cellulose acetate, steel, copper, wood, glass, and printed circuit boards. The first surface and the second surface may be independently selected from polypropylene, HDPE, and LDPE. The first surface and the second surface may be polypropylene. The first surface and the second surface may independently be selected from HDPE and LDPE.

[0087] The first surface may be selected from polypropylene (PP), poly(ethylene terephthalate) (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), polyvinyl chloride (PVC), polystyrene (PS), melamine, cellulose acetate, unspecified polymeric resins, metals (e.g., steel, copper), ceramics, silicon, wood, glass, and printed circuit boards. The first surface may be selected from polypropylene, poly(ethylene terephthalate), HDPE, LDPE, PVC, PS, melamine, cellulose acetate, unspecified polymeric resins, metals, ceramics, silicon, and glass. The first surface may be selected from polypropylene (PP), poly(ethylene terephthalate) (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), cellulose acetate, steel, copper, wood, glass, and printed circuit boards. The first surface may be selected from polypropylene, HDPE, and LDPE. The first surface may be polypropylene. The first surface may be selected from HDPE and LDPE.

[0088] The second surface may be selected from polypropylene (PP), poly(ethylene terephthalate) (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), polyvinyl chloride (PVC), polystyrene (PS), melamine, cellulose acetate, unspecified polymeric resins, metals (e.g., steel, copper), ceramics, silicon, wood, glass, and printed circuit boards. The second surface may be selected from polypropylene, poly(ethylene terephthalate), HDPE, LDPE, PVC, PS, melamine, cellulose acetate, unspecified polymeric resins, metals, ceramics, silicon, and glass. The second surfaces may be independently selected from polypropylene (PP), poly(ethylene terephthalate) (PET), high density polyethylene (HDPE), low density polyethylene (LDPE), cellulose acetate, steel, copper, wood, glass, and printed circuit boards. The second surface may be selected from polypropylene, HDPE, and LDPE. The second surface may be polypropylene. The second surface may be selected from HDPE and LDPE.

[0089] At least one of the first surface and the second surface can form a part of a flexible substrate. The first surface can form a part of a flexible substrate. The second surface can form a part of a flexible substrate. Each of the first surface and the second surface can form a part of a flexible substrate.

[0090] The method may be a method of labelling a bottle, wherein either the first surface or the second surface is an exterior surface of the bottle, and one of the first surface or the second surface is a label.

[0091] The aqueous emulsion is an aqueous emulsion comprising particles dispersed in an aqueous phase, the particles of the aqueous emulsion comprising a hydrophobic polymer, and the particles of the aqueous emulsion are positively charged.

[0092] The hydrophobic polymer may be polystyrene, polyacrylate, polymethacrylate, polyvinyl, polydiene, or a mixture / copolymer thereof. The hydrophobic polymer may be selected from polystyrene, poly(butyl acrylate), poly(styrene-butyl acrylate) copolymer, or polybutadiene. The hydrophobic polymer may be polystyrene, polyacrylate, polymethacrylate, or polyvinyl, or a mixture / copolymer thereof. The hydrophobic polymer may be selected from polystyrene, poly(butyl acrylate), or poly(styrene-butyl acrylate) copolymer. The hydrophobic polymer may be poly(styrene-butyl acrylate) copolymer.

[0093] When the hydrophobic polymer is a poly(styrene-butyl acrylate) copolymer, the copolymer may comprise styrene and butyl acrylate in a weight ratio ranging from 3:1 to 0.01:1, such as a weight ratio ranging from 1.5:1 to 1:1.5. The copolymer may also comprise styrene and butyl acrylate in a weight ratio of about 1:1.5.

[0094] The particles of the aqueous emulsion may further comprise a positively charged polymer (e.g., a polycation). The positively charged polymer (e.g., a polycation) may be associated with a hydrophobic polymer. For example, the positively charged polymer (e.g., a polycation) may be associated with a hydrophobic polymer through hydrophobic interactions, electrostatic interactions, or covalent interactions.

[0095] The components of the particle can be arranged and selected so that positively charged groups (e.g., amino groups) are located on the surface of the particle. The components of the particle can be arranged and selected so that the concentration of positively charged groups (e.g., amino groups) on the surface of the particle is higher than the concentration in the interior of the particle. Thus, the hydrophobic polymer can be located in the interior of the particle and the positively charged polymer can be located on the exterior of the particle.

[0096] A positively charged polymer may be a polymeric species that contains one or more positively charged groups. A positively charged polymer may be a polymeric species that contains multiple positively charged groups.

[0097] In certain embodiments, the aqueous emulsion has a pH of about 5 to about 8. Preferably, the aqueous emulsion has a pH of about 5. The positively charged polymer (e.g., a polycation) may contain one or more basic groups that are protonated to form cations at the pH of the first aqueous emulsion, for example, in the pH range of about 5 to about 8. The positively charged polymer (e.g., a polycation) may contain multiple basic groups that are protonated to form cations at the pH of the aqueous emulsion, for example, in the pH range of about 5 to about 8. The positively charged polymer (e.g., a polycation) may contain one or more amino groups. The positively charged polymer (e.g., a polycation) may contain multiple amino groups. The amino groups may be primary amino groups, secondary amino groups, or tertiary amino groups. The amino groups may be primary amino groups.

[0098] The positively charged polymer may be selected from the group including chitosan, polyaminoacrylate, polyaminomethacrylate, polyallylamine, polyethyleneimine. The positively charged polymer may be selected from chitosan, poly[2-(dimethylamino)ethyl acrylate], poly[2-(dimethylamino)ethyl methacrylate], and polyethyleneimine. The positively charged polymer may be chitosan.

[0099] The particles of the aqueous emulsion can be present in an amount ranging from about 20% to about 40% by weight of the aqueous emulsion. The particles of the aqueous emulsion can be present in an amount of about 30% by weight of the aqueous emulsion.

[0100] The particles of the aqueous emulsion may comprise a hydrophobic polymer and a positively charged polymer (eg, a polycation) in a ratio ranging from about 20:1 to about 60:1 by weight of the aqueous emulsion.

[0101] The aqueous emulsion may have a low shear viscosity in the range of about 25 to about 100 Pa·s. The aqueous emulsion may have a high shear viscosity in the range of about 50 to about 150 mPa·s.

[0102] The hydrophobic polymer has a glass transition temperature (T) of less than about 50°C, less than about 25°C, or less than about 20°C. g The hydrophobic polymer may have a glass transition temperature (T) above about -50°C. g The hydrophobic polymer may have a glass transition temperature (T) of about -50°C to about 50°C, about -50°C to about 25°C, about -50°C to about 20°C, about -25°C to about 20°C, about 0°C to about 20°C, or about 10°C to about 20°C. g ) may be included.

[0103] The particles of the aqueous emulsion may have a size in the range of about 0.1 to about 200 μm, optionally in the range of about 80 to about 200 μm. The particles of the aqueous emulsion may have a size in the range of about 10 nm to about 20 μm, optionally in the range of about 20 nm to about 10 μm.

[0104] The aqueous emulsion particles may further comprise one or more additives. The one or more additives may each comprise one or more sulfate groups. In an embodiment, the aqueous emulsion particles comprise a single additive. In an embodiment, the aqueous emulsion particles comprise a single additive comprising one or more sulfate groups.

[0105] Each additive may be a cationic surfactant. For example, the additive may be a cationic surfactant selected from alkylammonium halides or other alkylammonium salts. Specific examples of cationic surfactants include triethylamine hydrochloride, octenidine dihydrochloride, Adogen, cetrimonium bromide, cetylpyridinium chloride, benzethonium chloride, and dimethyldioctadecylammonium chloride.

[0106] The aqueous emulsion is an aqueous emulsion comprising particles dispersed in an aqueous phase, the particles of the aqueous emulsion comprising a hydrophobic polymer, and the particles of the aqueous emulsion are negatively charged.

[0107] The hydrophobic polymer may be polystyrene, polyacrylate, polymethacrylate, polyvinyl, polydiene, or a mixture / copolymer thereof. The hydrophobic polymer may be selected from polystyrene, poly(butyl acrylate), poly(styrene-butyl acrylate) copolymer, or polybutadiene. The hydrophobic polymer may be polystyrene, polyacrylate, polymethacrylate, or polyvinyl, or a mixture / copolymer thereof. The hydrophobic polymer may be selected from polystyrene, poly(butyl acrylate), or poly(styrene-butyl acrylate) copolymer. The hydrophobic polymer may be poly(styrene-butyl acrylate) copolymer.

[0108] When the hydrophobic polymer is a poly(styrene-butyl acrylate) copolymer, the copolymer may comprise styrene and butyl acrylate in a weight ratio ranging from 3:1 to 0.01:1, such as a weight ratio ranging from 1.5:1 to 1:1.5. The copolymer may also comprise styrene and butyl acrylate in a weight ratio of about 1:1.5.

[0109] The particles of the aqueous emulsion may further comprise a negatively charged polymer (e.g., a polyanion). The negatively charged polymer (e.g., a polyanion) may be associated with a hydrophobic polymer. For example, the negatively charged polymer (e.g., a polyanion) may be associated with the hydrophobic polymer through hydrophobic interactions, electrostatic interactions, or covalent interactions.

[0110] The components of the particle can be arranged and selected so that the negatively charged groups (e.g., carboxylate groups) are located on the surface of the particle. The components of the particle can be arranged and selected so that the concentration of negatively charged groups (e.g., carboxylate groups) on the surface of the particle is higher than the concentration in the interior of the particle. Thus, the hydrophobic polymer can be located in the interior of the particle and the negatively charged polymer can be located on the exterior of the particle.

[0111] The negatively charged polymer may be a polymeric species that contains one or more negatively charged groups. The negatively charged polymer may be a polymeric species that contains multiple negatively charged groups.

[0112] In certain embodiments, the aqueous emulsion has a pH of about 5 to about 8, optionally about 5. The negatively charged polymer (e.g., a polyanion) may contain one or more groups that deprotonate to form anions at the pH of the aqueous emulsion, for example, a pH range of about 5 to about 8. The negatively charged polymer (e.g., a polyanion) may contain multiple groups that deprotonate to form anions at the pH of the aqueous emulsion, for example, a pH range of about 5 to about 8. The negatively charged polymer (e.g., a polyanion) may contain carboxylate, sulfonate, phosphonate, or boronate groups. The negatively charged polymer (e.g., a polyanion) may contain one or more carboxylate groups. The negatively charged polymer (e.g., a polyanion) may contain multiple carboxylate groups.

[0113] The negatively charged polymer (e.g., polyanion) may be selected from the group including polyacrylic acid, acidic biopolymers, polysulfonic acid, and polymaleic acid. The negatively charged polymer (e.g., polyanion) may be selected from poly(acrylic acid), alginate, carboxymethylcellulose, xanthan gum, gum arabic, carrageenan, poly(2-acrylamido-2-methylpropanesulfonic acid), poly(methacrylic acid), poly(maleic acid), and poly(vinylsulfonic acid). The negatively charged polymer (e.g., polyanion) is poly(acrylic acid).

[0114] The particles of the aqueous emulsion can be present in an amount ranging from about 20% to about 40% by weight of the aqueous emulsion. The particles of the aqueous emulsion can be present in an amount of about 30% by weight of the aqueous emulsion.

[0115] The particles of the aqueous emulsion may comprise a hydrophobic polymer and a negatively charged polymer (eg, a polyanion) in a ratio ranging from about 20:1 to about 60:1 by weight of the aqueous emulsion.

[0116] The aqueous emulsion may have a low shear viscosity in the range of about 25 to about 100 Pa·s. The aqueous emulsion may have a high shear viscosity in the range of about 50 to about 150 mPa·s.

[0117] The hydrophobic polymer has a glass transition temperature (T) of less than about 50°C, less than about 25°C, or less than about 20°C. g The hydrophobic polymer may have a glass transition temperature (T) above about -50°C. g The hydrophobic polymer may have a glass transition temperature (T) of about -50°C to about 50°C, about -50°C to about 25°C, about -50°C to about 20°C, about -25°C to about 20°C, about 0°C to about 20°C, or about 10°C to about 20°C. g ) may be included.

[0118] The aqueous emulsion particles may further comprise one or more additives. The one or more additives may each comprise one or more sulfate groups. In an embodiment, the aqueous emulsion particles comprise a single additive. In an embodiment, the aqueous emulsion particles comprise a single additive comprising one or more sulfate groups.

[0119] Each additive may be an anionic surfactant. For example, the additive may be an anionic surfactant selected from alkyl sulfates, alkyl ether sulfates, and alkyl sulfonates. Preferably, the additive is sodium dodecyl sulfate.

[0120] The particles of the aqueous emulsion may have a size in the range of about 0.1 to about 200 μm, optionally in the range of about 80 to about 200 μm.

[0121] Embodiments of the present invention are further described below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0122] [Figure 1]1 shows exemplary first and second emulsions of an adhesive kit of the present invention. The first emulsion (left) contains a poly(styrene-co-butyl acrylate) core associated with chitosan. The second emulsion (right) contains a poly(styrene-co-butyl acrylate) core associated with poly(acrylic acid). [Figure 2] 1 shows images showing the appearance of poly(styrene-butyl acrylate) / chitosan (P(St-BA) / Chi) emulsions and films, and poly(styrene-butyl acrylate) / poly(acrylic acid) (P(St-BA) / PAA) emulsions and films. [Figure 3] FIG. 1 shows the proposed desorption mechanism of the first emulsion and the second emulsion of the adhesive kit of the present invention under high and low pH conditions. [Figure 4] 1 shows a representative image of reversible adhesion of the kit of the present invention at pH 1. [Figure 5] These images show the reversible adhesive behavior of P(St-BA) / Chi emulsions and P(St-BA) / PAA emulsions. Each sample contains a poly(ethylene terephthalate) (PET) first surface and a polypropylene (PP) second surface. Top row: pH = 1, middle row: pH = 7, bottom row: pH = 14. From left to right: a P(St-BA) / Chi-only conjugated sample; a P(St-BA) / PAA-only conjugated sample; a P(St-BA) / Chi-P(St-BA) / PAA conjugated sample with P(St-BA) / Chi coated on PET and P(St-BA) / PAA on PP; and a P(St-BA) / PAA-P(St-BA) / Ch conjugated sample with P(St-BA) / PAA on PET and P(St-BA) / Chi on PP. [Figure 6] Figure 1 shows images of the appearance of poly(styrene-butyl acrylate) / chitosan (P(St-BA) / Chi) emulsion and poly(styrene-butyl acrylate) / poly(acrylic acid) (P(St-BA) / PAA) emulsion as prepared (left) and after 90 days (right). [Figure 7]FIG. 1 is a graph showing light scattering spectra illustrating the change in particle size distribution over 6 months for A) P(St-BA) / Chi emulsion and B) P(St-BA) / PAA emulsion. [Figure 8] FIG. 1 is a graph showing light scattering spectra illustrating the change in particle size distribution over one year for A) P(St-BA) / Chi emulsion and B) P(St-BA) / PAA emulsion. [Figure 9] 1 is a graph showing the adhesion strength of P(St-BA) / Chi, P(St-BA) / PAA, and P(St-BA) / Chi-P(St-BA) / PAA systems wetted with a PET substrate. [Figure 10] 1 is a graph showing stress vs. strain curves for Example 2. A) A typical stress vs. strain curve for PP. B) A typical stress vs. strain curve for PET. DETAILED DESCRIPTION OF THE INVENTION

[0123] The term "polymer" as used herein can refer to a single polymer species, or to a polymer mixture that includes multiple polymer species mixed or bonded together to create a new material with physical properties that differ from each individual polymer species.

[0124] As used herein, the term "hydrophobic" refers to a species that repels or is not miscible with water.

[0125] The term "emulsion" as used herein can refer to a dispersion of particles in a liquid phase, where the particles and the liquid phase are immiscible with each other. The particles include a polymer, such as a first hydrophobic polymer or a second hydrophobic polymer. The particles can be solid particles, semi-solid particles, or liquid particles. The liquid phase is typically an aqueous phase. Therefore, the particles are typically hydrophobic.

[0126] As used herein, the term "glass transition" refers to the gradual, reversible transformation of an amorphous material from a hard, relatively brittle state to a viscous or rubbery state with increasing temperature.

[0127] As used herein, the term "glass transition temperature" or "T g " refers to the temperature or range of temperatures at which a glass transition occurs. The glass transition temperature is below the melting point of the crystalline state of the material.

[0128] As used herein, the terms "positively charged" and "negatively charged" refer to the charge state of the particles of the first and second aqueous emulsions at the pH of each emulsion, i.e., the pH of each aqueous phase. These terms can mean that the particles are positively or negatively charged at a pH in the range of about 5 to about 8, e.g., 7.

[0129] The term "organic solvent" can refer to a solvent system selected from hydrocarbons (e.g., petroleum ether, hexane, heptane), ethers (e.g., dimethylethylene glycol, diethyl ether, t-butyl methyl ether, tetrahydrofuran, dioxane), esters (e.g., ethyl acetate), ketones (e.g., acetone, t-butyl methyl ketone), amides (e.g., N-methylpyrrolidine, dimethylformamide, dimethylacetamide), sulfoxides (e.g., dimethyl sulfoxide), aromatic solvents (e.g., benzene, toluene), chlorinated solvents (e.g., chloroform, dichloromethane, 1,2-dichloroethane), turpentine, or mixtures thereof.

[0130] Throughout this description and the claims, the words "comprise" and "contain" and variations thereof mean "including but not limited to" and are not intended to (and do not) exclude other moieties, additives, components, integers, or steps. Throughout this description and the claims, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, it should be understood that the specification contemplates the plural as well as the singular unless the context otherwise requires.

[0131] It should be understood that any feature, integer, property, compound, chemical moiety, or group described in connection with a particular aspect, embodiment, or example of the invention is also applicable to any other aspect, embodiment, or example described herein, unless inconsistent therewith. All features disclosed herein (including any accompanying claims, abstract, and drawings), and / or all steps of any disclosed method or process, may be combined in any combination, except combinations where at least some such features and / or steps are mutually exclusive. The invention is not limited to the details of any of the foregoing embodiments. The invention extends to any novel or any novel combination of features, or any novel or any novel combination of steps of any disclosed method or process, disclosed herein (including any accompanying claims, abstract, and drawings).

[0132] The reader's attention is drawn to all articles and documents related to this application that have been filed contemporaneously or previously hereto and are open to public inspection herewith, the contents of which are incorporated herein by reference. [Example]

[0133] Materials and Methods Sodium dodecyl sulfate (SDS) (NAC 12 H 25 SO4, ≥98.5%), chitosan (Chi) (medium molecular weight), acetic acid (AAc) (CH3COOH, 99.8-100.5%), styrene (St) (C8H8, ≥99%), acrylated epoxidized soybean oil (AESO), butyl acrylate (BA) (C7H 12O2, stabilized for synthesis), acrylic acid (AA) (CH2CHCOOH, 99%), and potassium persulfate (KPS) (K2SO8 ≥ 99.0%) were all purchased from Sigma-Aldrich and used as received for emulsion synthesis. Hydrochloric acid (HCl) (37%), sodium hydroxide (NaOH) (≥ 98%), ethanol (analytical grade anhydrous), and acetone (≥ 99.5%) were purchased from Sigma-Aldrich and used as received for reversibility, swelling, and film stability studies. Distilled turpentine was purchased from Winsor & Newton Art Supplies and used for film stability studies.

[0134] 0.25 mm thick Mylar® plastic film (PET) and 0.127 mm thick polypropylene (PP) plastic film were purchased from RS Components and used for reversibility experiments. 0.25 mm thick Mylar® plastic film (PET) and 0.45 mm thick polypropylene plastic film were purchased from RS Components and used for lap shear strength measurements. Cyanoacrylate Superglue, purchased from RS Components, and hanging hooks, purchased from JELLYSUB, were used for tensile strength demonstrations.

[0135] Example 1 Synthesis of emulsion 1: poly(styrene-butyl acrylate) / chitosan (P(St-BA) / Chi) The synthesis of P(St-BA) / Chi was carried out by free radical emulsion polymerization. 20 mL of a 1.0 wt% acetic acid solution in deionized water was poured into a 100 mL three-neck flask in an oil bath, and 0.3 g of Chi was added and allowed to dissolve overnight (approximately 15 hours). The stirring speed was then increased, and 4.5 mL of BA and 3.5 mL of St were added dropwise over 10 minutes. A nitrogen flow was initiated. The emulsion was allowed to stand for 10 minutes and then heated to 70 °C. Once the temperature reached 60 °C, 40 mg of KPS in 1.2 mL of deionized water was added dropwise, and the stirring was reduced. Once the temperature reached 70 °C, the nitrogen flow was reduced, and the reaction was allowed to proceed for 4 hours. The resulting emulsion was collected in a vial and stored.

[0136] Synthesis of emulsion 2: poly(styrene-butyl acrylate) / poly(acrylic acid) (P(St-BA) / PAA) The synthesis of P(St-BA) / PAA was carried out by free radical emulsion polymerization. 20 mL of deionized water was poured into a 100 mL three-neck flask in an oil bath, and 0.3 g of sodium dodecyl sulfate (SDS) was added and dissolved with stirring for 5 minutes. Then, 5 mL of BA and 4 mL of St were added dropwise over 5 minutes, and a nitrogen flow was initiated. The emulsion was allowed to stand for 10 minutes and then heated to 70 °C. Once the temperature reached 60 °C, 1.2 mL of KPS solution (50 mg KPS in 1.5 mL water) was added dropwise. Once the temperature reached 70 °C, the nitrogen flow was reduced and the reaction was allowed to proceed for 2 hours. The remaining 0.3 mL of KPS solution was then added, followed by the dropwise addition of acrylic acid solution (0.750 mL AA in 1.5 mL water). The polymerization reaction proceeded for another 2 hours, and the resulting emulsion was collected in a vial and stored.

[0137] result Both the P(St-BA) / Chi emulsion and the P(St-BA) / PAA emulsion were white and had a paint-like texture. They could be easily spread onto plastic substrates with a brush, and in particular, PET films could be formed by drying the emulsions on flat plastic substrates. While the P(St-BA) / PAA emulsion remained white, the P(St-BA) / Chi emulsion acquired a yellowish color due to the presence of chitosan. Exemplary emulsions and films are shown in Figure 2.

[0138] The reversibility of the two-phase adhesive was evaluated at pH=1 and pH=14. Samples were prepared by coating polyethylene terephthalate (PET) and polypropylene (PP) films with each emulsion and then contact drying at room temperature. Two sets were prepared from each of three different batches and then immersed in deionized water, a pH=1 HCl solution, or a pH=14 NaOH solution at room temperature. The samples are listed in the table below.

[0139] [Table 1]

[0140] Adhesion was assessed periodically. After overnight exposure, adhesion was lost in samples exposed to acidic or alkaline solutions (Figures 4 and 5). Adhesion remained in samples immersed in water.

[0141] Room temperature stability (shelf life) was assessed by storing each emulsion in a glass vial and sealing it under specified conditions. The average storage temperature was 20°C, and the vials were stored away from direct sunlight. Stability was assessed based on appearance. In particular, the formation of a precipitate indicates emulsion destabilization. P(St-BA) / Chi showed phase separation after 25 days, but this was reversible by shaking and did not affect emulsion behavior. The emulsions were stable for 90 days under the conditions described.

[0142] Further stability studies were performed by storing the emulsions at temperatures between 16°C and 20°C for periods of 6 and 12 months. Stability was monitored by particle size measurement using light scattering analysis with a Zetasizer Nano. In a polystyrene cuvette, one drop of the prepared emulsion was diluted with 2 mL of water. Each measurement was repeated three times, and the mean particle size and polydispersity index (PDI) were recorded. The study was repeated monthly for 12 months.

[0143] [Table 2]

[0144] As shown in Table 2 above, after 6 months of storage, the average particle size of P(St-BA) / Chi increased from 306.0 nm to 350.8 nm. During the same period, the average particle size of P(St-BA) / PAA increased from 122.2 nm to 139.3 nm. After 12 months of storage, the average particle size of P(St-BA) / Chi increased from 306.0 nm to 459.0 nm, and the average particle size of P(St-BA) / PAA increased from 122.2 nm to 178.2 nm. These results are further illustrated by the light scattering spectra in Figures 7 and 8.

[0145] The adhesive force of the emulsions in the wet state was measured using a Stable Microsystems TA.XTplusC Texture Analyser. This instrument consists of a cylindrical probe that approaches a surface and measures the force required to remove the probe. PET films were attached to the bottom of the probe and to the surface. For every test, each was coated with a P(St-BA) / Chi emulsion or a P(St-BA) / PAA emulsion. First, a water control test was recorded to eliminate possible cohesive effects. The adhesive force between the P(St-BA) / Chi emulsion or the P(St-BA) / PAA emulsion and itself was recorded. The surface PET was then coated with a cationic emulsion, and the probe PET was coated with an anionic emulsion, and the adhesive force was measured. The probe speed was 50 mm min -1The probe was set to 0.5 N, held on the surface for 1 minute with a force of 0.5 N, and then retracted at the same speed. The results are shown in Figure 9.

[0146] Example 2 The lap shear strength of each adhesive formulation and system in Example 1 was measured using polypropylene (PP) and poly(ethylene terephthalate) (PET) as substrates. In a typical test, two plastic films were carefully cleaned with acetone and then lapped with a 0.5 in. 2 (approx. 3.2cm 2 The adhesive was applied to both films, joined with a force of 1 N, and excess adhesive was wiped off. After the adhesive had dried, a tensile test was performed on each sample.

[0147] The amounts of adhesive applied to the films were as follows: 175mg of P(St-BA) / Chi on PET 60 mg of P(St-BA) / Chi on PP 25mg of P(St-BA) / PAA on PET 30 mg of P(St-BA) / PAA on PP

[0148] The measured lap shear strengths are shown in Table 2 and the corresponding stress versus strain curves are shown in FIG.

[0149] [Table 3]

[0150] 0.5in 2 (approx. 3.2cm 2Further strength tests were performed on two low-density polyethylene (LDPE) films bonded with P(St-BA) / Chi at an overlap area of ​​100 mm, supporting a 300 g mass, and compared to a commercial cyanoacrylate adhesive supporting the same mass. Both adhesives were found to support the mass, but only the P(St-BA) / Chi bonded sample remained flexible, while the commercial adhesive produced a stiff, brittle joint. This advantage is observed for all adhesive formulations of the present invention.

[0151] Reversibility tests were performed on pairs of PP and PET samples bonded together using individual formulations and complementary adhesive systems. The samples were exposed to water, an HCl solution at pH 1, and an NaOH solution at pH 14. Samples bonded with either the P(St-BA) / Chi formulation alone or the P(St-BA) / PAA formulation alone were found not to separate under any condition, thereby demonstrating adhesive strength to different substrates. Separation from the substrate was achieved using solvents such as acetone or turpentine.

[0152] Adhesion was also achieved using the formulations of Examples 1 and 2 with substrates such as polyethylene, cellulose acetate, glass, wood, steel, copper, and printed circuit board surfaces.

Claims

1. a first aqueous emulsion comprising particles dispersed in a first aqueous phase, the particles of the first aqueous emulsion comprising a first hydrophobic polymer, and the particles of the first aqueous emulsion being positively charged; a second aqueous emulsion comprising particles dispersed in a second aqueous phase, the particles of the second aqueous emulsion comprising a second hydrophobic polymer, and the particles of the second aqueous emulsion being negatively charged; An adhesive kit comprising: An adhesive kit, wherein a first aqueous emulsion and a second aqueous emulsion are configured to reversibly adhere to each other.

2. The adhesive kit of claim 1 , wherein the particles of the first aqueous emulsion further comprise a positively charged polymer.

3. 3. The adhesive kit of claim 2, wherein the positively charged polymer comprises one or more basic groups that are protonated to form cations at the pH of the first aqueous emulsion.

4. 4. The adhesive kit of claim 2 or 3, wherein the positively charged polymer comprises one or more amino groups.

5. 5. The adhesive kit of claim 2, wherein the positively charged polymer is selected from chitosan, poly[2-(dimethylamino)ethyl acrylate], poly[2-(dimethylamino)ethyl methacrylate], and polyethyleneimine.

6. 6. The adhesive kit according to claim 1, wherein the particles of the second aqueous emulsion further comprise a negatively charged polymer.

7. 7. The adhesive kit of claim 6, wherein the negatively charged polymer comprises one or more groups that deprotonate to form anions at the pH of the second aqueous emulsion.

8. 8. The adhesive kit of claim 6 or 7, wherein the negatively charged polymer comprises one or more carboxylate, sulfonate, phosphonate, or boronate groups.

9. 9. The adhesive kit of claim 6, wherein the negatively charged polymer is selected from poly(acrylic acid), alginate, carboxymethyl cellulose, xanthan gum, gum arabic, carrageenan, poly(2-acrylamido-2-methylpropanesulfonic acid), poly(methacrylic acid), poly(maleic acid), and poly(vinylsulfonic acid).

10. 10. The adhesive kit according to claim 1, wherein the particles of the second aqueous emulsion further comprise an additive comprising one or more sulfate groups.

11. 11. The adhesive kit of claim 10, wherein the additive is sodium dodecyl sulfate.

12. 12. The adhesive kit according to claim 1, wherein the particles of the first aqueous emulsion are present in an amount of about 30% by weight of the first aqueous emulsion.

13. 13. The adhesive kit according to claim 1, wherein the particles of the second aqueous emulsion are present in an amount of about 30% by weight of the second aqueous emulsion.

14. 14. The adhesive kit of claim 1, wherein both the first hydrophobic polymer and the second hydrophobic polymer are poly(styrene-butyl acrylate) copolymers.

15. 15. The adhesive kit of claim 1, wherein the first aqueous emulsion and the second aqueous emulsion have a pH in the range of about 5 to about 8.

16. 16. The adhesive kit according to any one of claims 1 to 15, wherein the particles of the first aqueous emulsion and the particles of the second aqueous emulsion have a size of about 20 nm to about 10 μm.

17. 17. A method for adhering two surfaces to one another using an adhesive kit according to any one of claims 1 to 16, comprising the steps of: coating a first surface with a first aqueous emulsion; coating a second surface with a second aqueous emulsion; contacting a first surface coated with the first aqueous emulsion with a second surface coated with the second aqueous emulsion to bond the first surface and the second surface to each other at a bonding interface; A method comprising:

18. 20. The method of claim 17, further comprising lowering the pH of the first and second surfaces at the bond interface to separate the first and second surfaces from one another.

19. It is a method of labeling a bottle, 19. The method of claim 17 or 18, wherein either the first surface or the second surface is an outer surface of a bottle, and one of the first surface or the second surface is a label.

20. 17. A method of producing the adhesive kit of any one of claims 1 to 16, comprising forming a first aqueous emulsion and a second aqueous emulsion.

21. A method for adhering two surfaces to one another, comprising: coating the first surface and / or the second surface with an aqueous emulsion; contacting the first surface with the second surface and adhering the first surface and the second surface to one another at a bonding interface; Including, The aqueous emulsion is an aqueous emulsion comprising particles dispersed in an aqueous phase, the particles of the aqueous emulsion comprising a hydrophobic polymer, the particles of the aqueous emulsion being positively charged; and A method of preparing an aqueous emulsion comprising particles dispersed in an aqueous phase, wherein the particles of the aqueous emulsion comprise a hydrophobic polymer, and wherein the particles of the aqueous emulsion are selected from negatively charged aqueous emulsions.

22. 22. The method of claim 21, wherein the aqueous emulsion is an aqueous emulsion comprising particles dispersed in an aqueous phase, the particles of the aqueous emulsion comprising a hydrophobic polymer, and the particles of the aqueous emulsion are positively charged.

23. 23. The method of claim 22, wherein the particles of the aqueous emulsion further comprise a positively charged polymer.

24. 24. The method of claim 23, wherein the positively charged polymer comprises one or more basic groups that are protonated to form cations at the pH of the aqueous emulsion.

25. 25. The method of claim 23 or 24, wherein the positively charged polymer comprises one or more amino groups.

26. 26. The method of any one of claims 23 to 25, wherein the positively charged polymer is selected from chitosan, poly[2-(dimethylamino)ethyl acrylate], poly[2-(dimethylamino)ethyl methacrylate], and polyethyleneimine.

27. 22. The method of claim 21, wherein the aqueous emulsion is an aqueous emulsion comprising particles dispersed in an aqueous phase, the particles of the aqueous emulsion comprising a hydrophobic polymer, and the particles of the aqueous emulsion are negatively charged.

28. 28. The method of claim 27, wherein the particles of the aqueous emulsion further comprise a negatively charged polymer.

29. 29. The method of claim 28, wherein the negatively charged polymer comprises one or more groups that deprotonate to form anions at the pH of the aqueous emulsion.

30. 30. The method of claim 28 or 29, wherein the negatively charged polymer comprises one or more carboxylate, sulfonate, phosphonate, or boronate groups.

31. 31. The method of any one of claims 28 to 30, wherein the negatively charged polymer is selected from poly(acrylic acid), alginate, carboxymethylcellulose, xanthan gum, gum arabic, carrageenan, poly(2-acrylamido-2-methylpropanesulfonic acid), poly(methacrylic acid), poly(maleic acid), and poly(vinylsulfonic acid).

32. 32. The method of any one of claims 27 to 31, wherein the particles of the aqueous emulsion further comprise an additive comprising one or more sulfate groups.

33. 33. The method of claim 32, wherein the additive is sodium dodecyl sulfate.

34. 34. The method of any one of claims 21 to 33, wherein the particles of the aqueous emulsion are present in an amount of about 30% by weight of the aqueous emulsion.

35. 35. The method of any one of claims 21 to 34, wherein the hydrophobic polymer is a poly(styrene-butyl acrylate) copolymer.

36. 36. The method of any one of claims 21 to 35, wherein the aqueous emulsion has a pH in the range of about 5 to about 8.

37. 37. The method of any one of claims 21 to 36, wherein the particles of the aqueous emulsion have a size of from about 20 nm to about 10 μm.

38. 38. The method of any one of claims 21 to 37, wherein the first surface is selected from polypropylene, HDPE, and LDPE.

39. 39. The method of claim 38, wherein the second surface is selected from polypropylene, HDPE, and LDPE.

40. 38. The method of any one of claims 21 to 37, wherein at least one of the first surface and the second surface is polypropylene.

41. 38. The method of any one of claims 21 to 37, wherein both the first surface and the second surface are polypropylene.

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