Acrylate soap-free emulsion as well as preparation method and application thereof

Abstract

The invention provides an acrylate soap-free emulsion and a preparation method and application thereof, and belongs to the technical field of high-molecular polymer emulsions.The acrylate soap-free emulsion is prepared from, by mass, 30-50 parts of hard monomers, 20-40 parts of soft monomers, 1-10 parts of functional monomers, 0.4-0.6 part of free radical initiators, 0.1-0.3 part of pH regulators, 40-60 parts of solvents, 0.5-1 part of polymerizable emulsifiers and 0.5-1 part of compound emulsifiers. A soap-free emulsion technology is adopted, the adverse effects of a free emulsifier generated in a traditional emulsifier on the electrical performance, optical performance, surface performance, water resistance, film-forming property and the like of a polymerization product are avoided, in addition, the polymerizable emulsifier can be bonded to the surfaces of polymer particles in a covalent bond mode and becomes a part of a polymer, and the polymerization effect is good. Therefore, the influence of desorption caused by the free emulsifier or migration on the surface of a latex film is reduced, the stability of the emulsion is improved, the cost of the product is reduced, and the post-treatment process of the emulsifier is simplified.

Description

Technical Field

[0001] The invention relates to the technical field of high molecular polymer emulsions, and in particular to an acrylate soap-free emulsion and a preparation method and application thereof. Background Art

[0002] Acrylic emulsion is a major category of polymer emulsions. Acrylic emulsion refers to homopolymers, copolymers of acrylic monomers and various copolymers with other vinyl monomers. Acrylic emulsion has the advantages of simple synthesis process, stable emulsion, excellent performance, low price, and environmental protection. It has excellent film-forming property, good water resistance and weather resistance, excellent adhesion, etc. At present, it has been widely used in adhesives, coatings, printing and dyeing auxiliaries, building exterior wall coatings and other industries.

[0003] However, it is inevitable to add emulsifiers in traditional emulsion polymerization. Emulsifiers play a very important role in the synthesis and stabilization of emulsions. Emulsifiers need to be added to emulsion polymerization to stabilize the system and micelle nucleation. On the one hand, it will increase the cost and increase the post-processing process. On the other hand, the introduced emulsifiers will affect the properties of emulsion polymers such as electrical properties, surface properties, film-forming properties and water resistance. The rise of soap-free emulsion polymerization technology can overcome the disadvantages of emulsifiers in traditional emulsion polymerization. The surface of the prepared latex particles of soap-free emulsion is relatively clean and uniform in size. The emulsion contains very little or even no emulsifier, which eliminates the defects of poor electrical properties, optical properties, surface properties and water resistance caused by the use of emulsifiers in traditional emulsion polymerization. Soap-free emulsion polymerization refers to an emulsion polymerization process in which no emulsifier is added at all or only a trace amount of emulsifier (whose concentration is less than the critical micelle concentration CMC) is added during the reaction.

[0004] For high solid content emulsions, which contain very little water, they have the advantages of high production efficiency, low transportation cost, fast drying, and low energy consumption. However, high solid content is often accompanied by high viscosity. The viscosity of the emulsion has a great influence on the heat transfer, mass transfer, fluid flow, emulsion stability, and emulsion transportation during the entire reaction process. At the same time, excessive viscosity is also unfavorable for pipeline transportation and later application construction. Compared with conventional emulsions, high solid content soap-free emulsions not only improve the utilization rate of equipment and reduce the energy consumption per unit product during the polymerization process, but also have the advantages of high production efficiency, low transportation cost, fast emulsion drying and film formation speed, and no environmental pollution. However, due to the poor stability of high solid content emulsions, soap-free emulsion polymerization has process difficulties in large-scale production. Therefore, how to achieve a soap-free emulsion with both high solid content and high stability needs to be solved urgently. Among them, the emulsion prepared by patent CN 108047376 has a solid content of 45% and a viscosity of 170mPa·s, but it does not involve soap-free. The acrylic soap-free emulsion prepared in patent CN102115517 does not contain high solid and low viscosity. The above studies did not prepare an emulsion product that meets the requirements of high solid content and low viscosity based on the soap-free emulsion. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present application provides an acrylate soap-free emulsion and a preparation method and application thereof, aiming to solve the technical problems of poor stability of high-solid content emulsions and process difficulties in large-scale production of soap-free emulsion polymerization.

[0006] In a first aspect, an embodiment of the present application provides an acrylate soap-free emulsion, which comprises, by weight, 30 to 50 parts of a hard monomer, 20 to 40 parts of a soft monomer, 1 to 10 parts of a functional monomer, 0.4 to 0.6 parts of a free radical initiator, 0.1 to 0.3 parts of a pH adjuster, 40 to 60 parts of a solvent, 0.5 to 1 parts of a polymerizable emulsifier, and 0.5 to 1 parts of a compound emulsifier; The polymerizable emulsifier is one or more of 1-allyloxy-3-(4-nonylphenoxy)-2-propanol polyoxyethylene (10) ether, 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether monophosphate, 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, nonylphenol polyoxyethylene ether ammonium sulfate, alkylphenol polyoxyethylene ether, allyloxy fatty alcohol polyoxyethylene ether ammonium sulfate, sodium p-vinylbenzene sulfonate, sodium vinyl sulfonate, and sodium allyloxyhydroxypropane sulfonate; The compound emulsifier is one or more of nonylphenol polyoxyethylene ether acrylate, sorbitan trioleate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate.

[0007] In the technical solution of the embodiment of the present application, soap-free emulsion polymerization refers to the introduction of polymerizable emulsifiers or other special monomers to avoid the use of traditional free emulsifiers to stabilize the emulsion system. This method reduces the influence of free surfactants on the properties of the emulsion film, making the emulsion more stable and more water-resistant, and is widely used in the field of high-performance emulsion coatings and adhesives. The polymerizable emulsifier in the present application is a surfactant with an amphiphilic structure (hydrophilic group and hydrophobic group) and a polymerizable double bond, which can copolymerize with the monomer during the polymerization process and finally be firmly embedded in the surface of the latex particles. After the polymerizable emulsifier in the present application is embedded in the polymer chain in the polymerization reaction, a layer of polymer chain segments containing hydrophilic groups will be evenly arranged on the surface of the latex particles. These hydrophilic groups form electrostatic repulsion in water, thereby stabilizing the latex particles. After the polymerizable emulsifier embedded in the polymer chain is arranged on the surface of the latex particles, since the surface carries the same charge, a strong electrostatic repulsion is generated between the latex particles, preventing the latex particles from agglomerating and settling.

[0008] When only polymerizable emulsifiers are used, due to the sparse molecular arrangement, the electrostatic repulsion on the surface of the latex particles is large, which easily leads to the emulsifier layer on the surface of the latex particles being not tight enough, thereby reducing the stability of the emulsion. Therefore, using only polymerizable emulsifiers cannot meet the stability requirements of high solid content emulsions. The non-ionic properties of compound emulsifiers make them uncharged. When the compound emulsifiers are adsorbed on the surface of latex particles, they can effectively fill the gaps between polymerizable emulsifier molecules and increase the distance between polymerizable emulsifier molecules of the same charge, thereby reducing the electrostatic repulsion on the surface of the latex particles and enhancing the stability of the emulsion.

[0009] In some embodiments, the hard monomer is one or more of methyl methacrylate, ethyl methacrylate, octadecyl methacrylate, and dodecanedephthene fluoromethacrylate in the methacrylate class.

[0010] In some embodiments, the soft monomer includes one or more of methyl acrylate, ethyl acrylate, butyl acrylate, dibutyl acrylate, vinyl acrylate, and isooctyl methacrylate.

[0011] In some embodiments, the functional monomer is an organic compound containing one or more groups of hydroxyl, carboxyl, cyano, epoxy, amino, or fluorine or chlorine in its molecular structure.

[0012] In some embodiments, the functional monomer includes one or more of acrylic acid, hydroxypropyl acrylate, acrylamide, hydroxymethyl acrylamide, ethyl acetoacetate methacrylate, dimethylaminoethyl methacrylate, glycidyl methacrylate, and trifluoroethyl methacrylate.

[0013] In some embodiments, the free radical initiator is one or more of potassium persulfate, ammonium persulfate, and azobisisobutyramidine hydrochloride.

[0014] In some embodiments, the pH adjuster is sodium bicarbonate and the solvent is deionized water.

[0015] In a second aspect, the present invention provides a method for preparing an acrylic acid soap-free emulsion, comprising the following steps: S1, mixing the reactive emulsifier A, the compound emulsifier and the solvent to obtain an emulsifier aqueous solution; Mixing the hard monomer, the soft monomer and the functional monomer to obtain a monomer mixture; The pH adjusting liquid and the emulsifier aqueous solution are mixed, the monomer mixed solution is added dropwise thereto, and pre-emulsification is performed at a temperature of 40 to 50° C. to obtain a pre-emulsified solution; S2. In a nitrogen atmosphere and at a temperature of 70-80°C, the pre-emulsion and the free radical initiator are reacted by a semi-continuous dropwise addition method. After the reaction is completed, the pre-emulsion is cooled to 40°C, the pH is adjusted to 8.0 with aqueous ammonia, and the acrylate soap-free emulsion is obtained after filtration.

[0016] In the technical solution of the embodiment of the present application, in step S2, the pre-emulsifier accounting for 5% of the total mass of the pre-emulsifier and the free radical initiator accounting for 5% of the total mass of the free radical initiator are first mixed and reacted, and then the remaining emulsifier and the free radical initiator are reacted by a semi-continuous dropwise addition method; the reaction conditions are: the reaction temperature is 70~80°C, and the reaction time is 2.5~3.5h.

[0017] In a third aspect, the embodiments of the present application provide an application of an acrylic soap-free emulsion, which is used in adhesives, coatings, and printing and dyeing auxiliaries.

[0018] Different from the existing technical solutions, the beneficial effects of this application include: 1. The present application adopts soap-free emulsion technology to avoid the adverse effects of free emulsifiers produced in traditional emulsifiers on the electrical properties, optical properties, surface properties, water resistance and film-forming properties of the polymer product. In addition, the polymerizable emulsifier can be bonded to the surface of the polymer particles in the form of covalent bonds and become a part of the polymer, thereby reducing the desorption of free emulsifiers or the effects of migration on the surface of the latex film, improving the stability of the emulsion, thereby reducing the cost of the product and simplifying the post-processing process of the emulsifier.

[0019] The compound emulsifier in this application complements the performance of the polymerizable emulsifier, so that the soap-free acrylic emulsion has better stability. After the polymerizable emulsifier A is bonded to the soap-free acrylic emulsion polymer molecule, a layer of charges of the same sign is evenly arranged on the surface of the latex particles, generating a huge electrostatic repulsion, which increases the distance between the polymerizable emulsifier molecules in the emulsion. The sparse arrangement of the polymerizable emulsifier molecules is not conducive to improving the stability of the emulsion. After using the compound emulsifier, the compound emulsifier molecules are arranged in the middle of the polymerizable emulsifier, which increases the distance between the same emulsifiers on the surface of the latex particles, thereby reducing the electrostatic repulsion on the surface of the same latex particle, and the emulsifier is more firmly adsorbed on the latex particles, making the polymer emulsion more stable.

[0020] 2. This application adopts a semi-continuous seed emulsion polymerization method to add reactants in three stages to allow the reaction to proceed fully. A polymerizable emulsifier and a compound emulsifier are used to rely on the synergistic effect of charge repulsion and hydration layer, so that the latex particles can be stably dispersed in the water phase, thereby preparing a stable emulsion. This application can prepare a soap-free emulsion with high solid content and low viscosity. The solid content can reach 60%, and the viscosity can be maintained within 150mPa·s. The high-solid content emulsion can not only increase the drying and film-forming speed of the emulsion, but also reduce storage and transportation costs. In terms of application, it can meet the requirements of coatings, adhesives, etc. that require high solid content (mass fraction ≥50%) and low electrolytes and contain other water-soluble substances.

[0021] 3. The solvent used in this application is deionized water, which reduces the emission of VOCs during use and avoids harm to human health and environmental pollution.

[0022] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. DETAILED DESCRIPTION

[0023] The following is a detailed description of the embodiments of the technical solution of the present application. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the description and claims of this application and any variations thereof are intended to cover non-exclusive inclusions.

[0025] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0026] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0028] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0029] For high-solid emulsions, which contain very little water, they have the advantages of high production efficiency, low transportation cost, fast drying, and low energy consumption. However, high solid content is often accompanied by high viscosity. The viscosity of the emulsion has a great impact on the heat transfer, mass transfer, fluid flow, emulsion stability, and emulsion transportation during the entire reaction process. At the same time, excessive viscosity is also unfavorable for pipeline transportation and later application construction. Compared with conventional emulsions, high-solid soap-free emulsions not only improve the utilization rate of equipment and reduce the energy consumption per unit product during the polymerization process, but also have the advantages of high production efficiency, low transportation cost, fast emulsion drying and film formation speed, and no environmental pollution. However, due to the poor stability of high-solid emulsions, soap-free emulsion polymerization has process difficulties in large-scale production.

[0030] In order to solve the technical problems of poor stability of high-solid emulsions and process difficulties in soap-free emulsion polymerization in large-scale production, the present application provides an acrylate soap-free emulsion and its preparation method and application, wherein the present application can prepare a soap-free emulsion with high solid content and low viscosity, the solid content can reach 60%, and the viscosity can be maintained within 150mPa·s. The high-solid emulsion can not only increase the drying film-forming speed of the emulsion, but also reduce storage and transportation costs. In terms of application, it can meet the requirements of coatings, adhesives, etc. that require high solid content (mass fraction ≥ 50%) and low electrolytes and contain other water-soluble substances.

[0031] In a first aspect, an embodiment of the present application provides an acrylate soap-free emulsion, which comprises, by weight, 30 to 50 parts of a hard monomer, 20 to 40 parts of a soft monomer, 1 to 10 parts of a functional monomer, 0.4 to 0.6 parts of a free radical initiator, 0.1 to 0.3 parts of a pH adjuster, 40 to 60 parts of a solvent, 0.5 to 1 parts of a polymerizable emulsifier, and 0.5 to 1 parts of a compound emulsifier; The polymerizable emulsifier is one or more of 1-allyloxy-3-(4-nonylphenoxy)-2-propanol polyoxyethylene (10) ether, 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether monophosphate, 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, nonylphenol polyoxyethylene ether ammonium sulfate, alkylphenol polyoxyethylene ether, allyloxy fatty alcohol polyoxyethylene ether ammonium sulfate, sodium p-vinylbenzene sulfonate, sodium vinyl sulfonate, and sodium allyloxyhydroxypropane sulfonate; The compound emulsifier is one or more of nonylphenol polyoxyethylene ether acrylate, sorbitan trioleate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate.

[0032] In some embodiments, the hard monomer is one or more of methyl methacrylate, ethyl methacrylate, octadecyl methacrylate, and dodecanedephthene fluoromethacrylate in the methacrylate class.

[0033] In some embodiments, the soft monomer includes one or more of methyl acrylate, ethyl acrylate, butyl acrylate, dibutyl acrylate, vinyl acrylate, and isooctyl methacrylate.

[0034] In some embodiments, the functional monomer is an organic compound containing one or more groups of hydroxyl, carboxyl, cyano, epoxy, amino, or fluorine or chlorine in its molecular structure.

[0035] In some embodiments, the functional monomer includes one or more of acrylic acid, hydroxypropyl acrylate, acrylamide, hydroxymethyl acrylamide, ethyl acetoacetate methacrylate, dimethylaminoethyl methacrylate, glycidyl methacrylate, and trifluoroethyl methacrylate.

[0036] In some embodiments, the free radical initiator is one or more of potassium persulfate, ammonium persulfate, and azobisisobutyramidine hydrochloride.

[0037] In some embodiments, the pH adjuster is sodium bicarbonate and the solvent is deionized water.

[0038] In a second aspect, the present invention provides a method for preparing an acrylic acid soap-free emulsion, comprising the following steps: S1, mixing the reactive emulsifier A, the compound emulsifier and the solvent to obtain an emulsifier aqueous solution; Mixing the hard monomer, the soft monomer and the functional monomer to obtain a monomer mixture; The pH adjusting liquid and the emulsifier aqueous solution are mixed, the monomer mixed solution is added dropwise thereto, and pre-emulsification is performed at a temperature of 40 to 50° C. to obtain a pre-emulsified solution; S2. In a nitrogen atmosphere and at a temperature of 70-80°C, the pre-emulsion and the free radical initiator are reacted by a semi-continuous dropwise addition method. After the reaction is completed, the pre-emulsion is cooled to 40°C, the pH is adjusted to 8.0 with aqueous ammonia, and the acrylate soap-free emulsion is obtained after filtration.

[0039] In the technical solution of the embodiment of the present application, in step S2, the pre-emulsifier accounting for 5% of the total mass of the pre-emulsifier and the free radical initiator accounting for 5% of the total mass of the free radical initiator are first mixed and reacted, and then the remaining emulsifier and the free radical initiator are reacted by a semi-continuous dropwise addition method; the reaction conditions are: the reaction temperature is 70~80°C, and the reaction time is 2.5~3.5h.

[0040] In a third aspect, the embodiments of the present application provide an application of an acrylic soap-free emulsion, which is used in adhesives, coatings, and printing and dyeing auxiliaries.

[0041] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0042] 1. Preparation method Example 1 The preparation method of the high solid content and low viscosity soap-free acrylic emulsion comprises the following steps: S1, 0.5 parts of 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, 0.5 parts of nonylphenol polyoxyethylene ether acrylate and 50 parts of deionized water are mixed uniformly to obtain an emulsifier aqueous solution; Mix 40 parts of ethyl methacrylate, 40 parts of methyl acrylate, and 10 parts of hydroxypropyl acrylate to obtain a monomer mixture; Add 0.1 parts of the prepared sodium bicarbonate solution and 51 parts of the stirred emulsifier aqueous solution into a dry container, start stirring, add the monomer mixture dropwise, and perform pre-emulsification at a temperature of 40-50°C for 30 minutes; S2, nitrogen was introduced into a dry container for half an hour, and the temperature was raised to the polymerization temperature of 70°C while nitrogen was introduced. After the temperature was raised, 7 parts of pre-emulsion were added as seed pre-emulsion, and 0.02 parts of initiator solution were added at the same time. Then, the remaining pre-emulsion and initiator were added dropwise in three stages using a peristaltic pump by semi-continuous addition method for reaction; the reaction conditions were: stirring speed 300 rpm, dropping time 2.5 h; After there is no reflux in the container, add initiator solution, raise the temperature to 80°C and keep it for 1 hour, cool to 40°C, adjust the pH to 8.0 with ammonia water (pure ammonia water and water mixed in a 1:1 ratio), stop stirring, discharge the material, and filter to obtain a high solid content and low viscosity soap-free acrylic emulsion.

[0043] Example 2 This embodiment is different from the embodiment 1 in that the hard monomer in the formula is methyl methacrylate, the soft monomer is butyl acrylate, and the functional monomer is acrylic acid. The other steps, reagents and parameters are the same as those in the embodiment 1. The ingredients and process parameters are as follows: (1) The soap-free emulsion comprises, by weight, 40 parts of methyl methacrylate, 40 parts of butyl acrylate, 10 parts of acrylic acid, 0.4 parts of potassium persulfate, 0.1 parts of sodium bicarbonate, 50 parts of deionized water, 0.5 parts of 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, and 0.5 parts of nonylphenol polyoxyethylene ether acrylate.

[0044] (2) Process conditions: pre-emulsification temperature 40°C, polymerization temperature 70°C, stirring speed 300 rpm, dropwise addition time 2.5 h, heating to 80°C and keeping warm for 1 h.

[0045] Example 3 This embodiment is different from the embodiment 1 in that the hard monomer in the formula is methyl methacrylate, the soft monomer is isooctyl methacrylate, and the functional monomer is glycidyl methacrylate. The other steps, reagents and parameters are the same as those in the embodiment 1. The ingredients and process parameters are as follows: (1) The soap-free emulsion comprises, by weight, 40 parts of methyl methacrylate, 40 parts of isooctyl methacrylate, 10 parts of glycidyl methacrylate, 0.4 parts of potassium persulfate, 0.1 parts of sodium bicarbonate, 50 parts of deionized water, 0.5 parts of 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, and 0.5 parts of nonylphenol polyoxyethylene ether acrylate.

[0046] (2) Process conditions: pre-emulsification temperature 40°C, polymerization temperature 70°C, stirring speed 300 rpm, dropwise addition time 2.5 h, heating to 80°C and keeping warm for 1 h.

[0047] Example 4 This embodiment is different from the embodiment 1 in that the formula composition is 50 parts of hard monomer, 49 parts of soft monomer, and 1 part of functional monomer. The other steps, reagents and parameters are the same as those in the embodiment 1. The composition and process parameters are as follows: (1) The soap-free emulsion comprises, by weight, 50 parts of ethyl methacrylate, 49 parts of methyl acrylate, 1 part of hydroxypropyl acrylate, 0.4 parts of potassium persulfate, 0.1 parts of sodium bicarbonate, 50 parts of deionized water, 0.5 parts of 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, and 0.5 parts of nonylphenol polyoxyethylene ether acrylate.

[0048] (2) Process conditions: pre-emulsification temperature 40°C, polymerization temperature 70°C, stirring speed 300 rpm, dropwise addition time 2.5 h, heating to 80°C and keeping warm for 1 h.

[0049] Example 5 This embodiment is different from embodiment 1 in that the compound emulsifier in the formula is polyoxyethylene sorbitan monooleate, and the other steps, reagents and parameters are the same as those in embodiment 1. The ingredients and process parameters are as follows: (1) The soap-free emulsion comprises, by weight, 40 parts of ethyl methacrylate, 40 parts of methyl acrylate, 10 parts of hydroxypropyl acrylate, 0.4 parts of potassium persulfate, 0.1 parts of sodium bicarbonate, 50 parts of deionized water, 0.5 parts of 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, and 0.5 parts of polyoxyethylene sorbitan monooleate.

[0050] (2) Process conditions: pre-emulsification temperature 40°C, polymerization temperature 70°C, stirring speed 300 rpm, dropwise addition time 2.5 h, heating to 80°C and keeping warm for 1 h.

[0051] Example 6 This embodiment is different from embodiment 1 in that the process conditions are polymerization temperature of 74° C., stirring speed of 350 rpm, and dropping time of 3 h. The other steps, reagents, and parameters are the same as those in embodiment 1. The components and process parameters are as follows: (1) The soap-free emulsion comprises, by weight, 40 parts of ethyl methacrylate, 40 parts of methyl acrylate, 10 parts of hydroxypropyl acrylate, 0.4 parts of potassium persulfate, 0.1 parts of sodium bicarbonate, 50 parts of deionized water, 0.5 parts of 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, and 0.5 parts of nonylphenol polyoxyethylene ether acrylate.

[0052] (2) Process conditions: pre-emulsification temperature 40°C, polymerization temperature 74°C, stirring speed 350 rpm, dropwise addition time 3 h, heating to 80°C and keeping warm for 1 h.

[0053] Example 7 This embodiment is different from embodiment 1 in that the process conditions are polymerization temperature of 78° C., stirring speed of 350 rpm, and dropping time of 3.5 h. The other steps, reagents and parameters are the same as those of embodiment 1. The components and process parameters are as follows: (1) The soap-free emulsion comprises, by weight, 40 parts of ethyl methacrylate, 40 parts of methyl acrylate, 10 parts of hydroxypropyl acrylate, 0.4 parts of potassium persulfate, 0.1 parts of sodium bicarbonate, 50 parts of deionized water, 0.5 parts of 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, and 0.5 parts of nonylphenol polyoxyethylene ether acrylate.

[0054] (2) Process conditions: pre-emulsification temperature 40°C, polymerization temperature 70°C, stirring speed 300 rpm, dropwise addition time 2.5 h, heating to 80°C and keeping warm for 1 h.

[0055] Example 8 This embodiment is different from embodiment 1 in that: the process conditions are polymerization temperature of 80°C, stirring speed of 350rpm, dropping time of 3.5h, heating to 85°C and keeping warm, and other steps, reagents and parameters are the same as those in embodiment 1, and the ingredients and process parameters are as follows: (1) The soap-free emulsion comprises, by weight, 40 parts of ethyl methacrylate, 40 parts of methyl acrylate, 10 parts of hydroxypropyl acrylate, 0.4 parts of potassium persulfate, 0.1 parts of sodium bicarbonate, 50 parts of deionized water, 0.5 parts of 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, and 0.5 parts of nonylphenol polyoxyethylene ether acrylate.

[0056] (2) Process conditions: pre-emulsification temperature 40°C, polymerization temperature 80°C, stirring speed 350 rpm, dropwise addition time 3.5 h, heating to 85°C and keeping warm for 1 h.

[0057] Comparative Example 1 0.5 parts of 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate and 50 parts of deionized water were mixed to obtain an emulsifier aqueous solution; Mix 40 parts of ethyl methacrylate, 40 parts of methyl acrylate, and 10 parts of hydroxypropyl acrylate to obtain a monomer mixture; Add 0.1 parts of the prepared sodium bicarbonate solution and 51 parts of the stirred emulsifier aqueous solution into a dry container, start stirring, add the monomer mixture dropwise, and perform pre-emulsification at a temperature of 40-50°C for 30 minutes; Nitrogen was introduced into a dry container for half an hour, and the temperature was raised to the polymerization temperature of 70°C while nitrogen was introduced. After the temperature was raised, 7 parts of pre-emulsion were added as seed pre-emulsion, and 0.02 parts of initiator solution were added at the same time. Then, the remaining pre-emulsion and initiator were added dropwise in three stages using a peristaltic pump by semi-continuous dropping method for reaction. The reaction conditions were: stirring speed 300 rpm, dropping time 2.5 h; After there is no reflux in the container, add initiator solution, raise the temperature to 80°C and keep it for 1 hour, cool to 40°C, adjust the pH to 8.0 with ammonia water (pure ammonia water and water mixed in a 1:1 ratio), stop stirring, discharge the material, and filter to obtain a high solid content and low viscosity soap-free acrylic emulsion.

[0058] Comparative Example 2 0.5 parts of nonylphenol polyoxyethylene ether acrylate and 50 parts of deionized water are mixed evenly to obtain an emulsifier aqueous solution and 50 parts of deionized water are mixed evenly to obtain an emulsifier aqueous solution; Mix 40 parts of ethyl methacrylate, 40 parts of methyl acrylate, and 10 parts of hydroxypropyl acrylate to obtain a monomer mixture; Add 0.1 parts of the prepared sodium bicarbonate solution and a uniformly stirred trace amount of emulsifier aqueous solution into a dry container, start stirring, drop the monomer mixture into it, and pre-emulsify at a temperature of 40-50°C for 30 minutes; Nitrogen was introduced into a dry container for half an hour, and the temperature was raised to the polymerization temperature of 70°C while nitrogen was introduced. After the temperature was raised, 7 parts of pre-emulsion were added as seed pre-emulsion, and 0.02 parts of initiator solution were added at the same time. Then, the remaining pre-emulsion and initiator were added dropwise in three stages using a peristaltic pump by semi-continuous dropping method for reaction. The reaction conditions were: stirring speed 300 rpm, dropping time 2.5 h; After there is no reflux in the container, add initiator solution, raise the temperature to 80°C and keep it for 1 hour, cool to 40°C, adjust the pH to 8.0 with ammonia water (pure ammonia water and water mixed in a 1:1 ratio), stop stirring, discharge the material, and filter to obtain a high solid content and low viscosity soap-free acrylic emulsion.

[0059] 2. Test Method The soap-free emulsions provided in the above examples and comparative examples were subjected to performance tests, mainly including performance parameters such as solid content, viscosity, gel fraction, and water absorption, and the test standards are as follows: 1. Solid content: GB / T 11175-2021; 2. Viscosity: GB / T 11175-2021; 3. Gel content: GB / T 11175-2021; 4. Water absorption: GB / T 1733-93.

[0060] 5. Stability: GB / T 11175-2021 III. Analysis of test results of various embodiments and comparative examples (1) The soap-free emulsions provided in the above examples and comparative examples were subjected to performance tests. The test results are shown in Table 1 below.

[0061] Table 1 Performance test parameters of acrylic acid soap-free emulsion in various examples and comparative examples

[0062] From the performance test results of each acrylic ester soap-free emulsion in Table 1, it can be seen that the soap-free emulsions prepared in Examples 2-8 have a solid content of not less than 60%, a viscosity of less than 150 mPa·s, a gel fraction of less than 1.7%, and a water absorption rate of less than 13%. Compared with Example 1, Examples 2 and 3 change the types of soft and hard monomers and functional monomers, the solid content is increased, the viscosity is reduced, and the compatibility of the three selected monomers is better than that of Example 1.

[0063] Compared with Example 1, Example 4 changes the mass ratio of the soft monomer, hard monomer and functional monomer. Under this mass ratio condition, the solid content is increased by 0.56% compared with Example 1, and the viscosity is greatly reduced. Under this condition, the performance requirements of high solid content and low viscosity can be met.

[0064] Example 5: By changing the types of polymerizable emulsifier and compound emulsifier, the synergistic effect of the two emulsifiers is more significant, the viscosity is greatly reduced after compounding, and the amount of gel in the system is very small. By compounding the two emulsifiers, the polymer emulsion is more stable.

[0065] In Examples 6, 7, and 8, the synthesis process conditions are changed. The temperature is increased, which is beneficial to the synthesis of high solid content. However, too high a temperature will affect the decrease in product viscosity and increase the gel fraction. Prolonging the reaction time is beneficial to the synthesis of high solid content, low viscosity soap-free emulsion, and increasing the insulation temperature has a positive effect on the solid content of the emulsion.

[0066] (2) The stability of the emulsions prepared in Example 1 and Comparative Examples 1-2 was tested. The test results are shown in Table 2 below.

[0067] Table 2 Stability test results of the emulsions in Example 1 and the comparative examples

[0068] It can be seen from Table 2 that the stability of the emulsion using a single polymerizable emulsifier or a compound emulsifier is poor, and the emulsion stability is maintained well when a polymerizable emulsifier and a compound emulsifier are used in combination.

[0069] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. An acrylic acid soap-free emulsion, characterized in that: By mass, it includes 30-50 parts of hard monomer, 20-40 parts of soft monomer, 1-10 parts of functional monomer, 0.4-0.6 parts of free radical initiator, 0.1-0.3 parts of pH adjuster, 40-60 parts of solvent, 0.5-1 parts of polymerizable emulsifier, and 0.5-1 parts of compound emulsifier; The polymerizable emulsifier is one or more of 1-allyloxy-3-(4-nonylphenoxy)-2-propanol polyoxyethylene (10) ether, 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether monophosphate, 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate, nonylphenol polyoxyethylene ether ammonium sulfate, alkylphenol polyoxyethylene ether, allyloxy fatty alcohol polyoxyethylene ether ammonium sulfate, sodium p-vinylbenzene sulfonate, sodium vinyl sulfonate, and sodium allyloxyhydroxypropane sulfonate; The compound emulsifier is one or more of nonylphenol polyoxyethylene ether acrylate, sorbitan trioleate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate.

2. The acrylate soap-free emulsion according to claim 1, characterized in that The hard monomer is one or more of methyl methacrylate, ethyl methacrylate, octadecyl methacrylate and dodecanedephthene fluoromethacrylate in the methacrylate class.

3. The acrylate soap-free emulsion according to claim 1, characterized in that The soft monomer includes one or more of methyl acrylate, ethyl acrylate, butyl acrylate, dibutyl acrylate, vinyl acrylate and isooctyl methacrylate.

4. The acrylate soap-free emulsion according to claim 1, characterized in that The functional monomer is an organic compound containing one or more groups of hydroxyl, carboxyl, cyano, epoxy, amino or fluorine and chlorine elements in its molecular structure.

5. The acrylate soap-free emulsion according to claim 4, characterized in that The functional monomers include one or more of acrylic acid, hydroxypropyl acrylate, acrylamide, hydroxymethyl acrylamide, ethyl acetoacetate methacrylate, dimethylaminoethyl methacrylate, glycidyl methacrylate and trifluoroethyl methacrylate.

6. The acrylate soap-free emulsion according to claim 1, characterized in that The free radical initiator is one or more of potassium persulfate, ammonium persulfate, and azobisisobutyramidine hydrochloride.

7. The acrylate soap-free emulsion according to claim 1, characterized in that The pH regulator is sodium bicarbonate, and the solvent is deionized water.

8. The method for preparing an acrylate soap-free emulsion according to any one of claims 1 to 7, characterized in that: The steps include: S1, mixing the reactive emulsifier A, the compound emulsifier and the solvent to obtain an emulsifier aqueous solution; Mixing the hard monomer, the soft monomer and the functional monomer to obtain a monomer mixture; The pH adjusting liquid and the emulsifier aqueous solution are mixed, the monomer mixed solution is added dropwise thereto, and pre-emulsification is performed at a temperature of 40 to 50° C. to obtain a pre-emulsified solution; S2. In a nitrogen atmosphere and at a temperature of 70-80°C, the pre-emulsion and the free radical initiator are reacted by a semi-continuous dropwise addition method. After the reaction is completed, the pre-emulsion is cooled to 40°C, the pH is adjusted to 8.0 with aqueous ammonia, and the acrylate soap-free emulsion is obtained after filtration.

9. The method for preparing an acrylic acid ester soap-free emulsion according to claim 8, characterized in that: In the step S2, firstly, 5% of the pre-emulsifier by weight and 5% of the free radical initiator by weight are mixed for reaction, and then the remaining emulsifier and the free radical initiator are reacted by semi-continuous addition method; the reaction conditions are: reaction temperature of 70-80° C., reaction time of 2.5-3.5 h.

10. The use of an acrylate soap-free emulsion according to any one of claims 1 to 7, characterized in that: Application in adhesives, coatings, and printing and dyeing auxiliaries.

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