Self-emulsifiable modified epoxy resin, method for its preparation and aqueous emulsion thereof

Abstract

The present invention relates to a self-emulsifiable modified epoxy resin, which comprises: a main chain comprising an epoxy resin segment and a segment derived from a di-carboxyl-terminated polyethylene glycol, a side chain derived from an unsaturated fatty acid, and a side chain derived from an olefinic bond-containing copolymerizable monomer, the olefinic bond-containing copolymerizable monomer comprising one or more (meth)acrylate copolymerizable monomers; wherein the segment derived from the di-carboxyl-terminated polyethylene glycol is grafted by ring-opening reaction of the di-carboxyl-terminated polyethylene glycol with the epoxy resin, and the molar ratio of the di-carboxyl-terminated polyethylene glycol to the epoxy resin in the ring-opening reaction is 1:1-6. Furthermore, the invention also relates to a preparation method of the above-mentioned epoxy resin and an aqueous emulsion comprising the same. The self-emulsifiable modified epoxy resin of the present application can spontaneously emulsify to form a single-component aqueous epoxy resin emulsion when mixed with water.

Description

Technical Field

[0001] This application relates to the field of polymer materials, specifically to a self-emulsifying modified epoxy resin, its preparation method, and its aqueous emulsion. Background Technology

[0002] Epoxy resins are widely used in coatings due to their numerous excellent properties. Two-component epoxy resin emulsions are common as epoxy resin-based coatings; however, they suffer from drawbacks such as cumbersome application and short operating windows because they require the on-site addition of a curing agent and mixing to prepare the target coating. Therefore, one-component epoxy resin emulsions that do not require a curing agent have become a research hotspot in this field. Existing one-component epoxy resin emulsions are typically prepared by ring-opening modification of the epoxy resin with unsaturated fatty acids (USFA) and the introduction of hydrophilic groups such as carboxyl groups; however, the resulting modified epoxy resins (usually anionic epoxy resins) often require neutralization to form salts, and the residual neutralizing agent (acid or alkali) deteriorates the coating's water and acid / alkali resistance. Furthermore, other one-component epoxy resins have been developed, but they either lack self-emulsifying capabilities and require external emulsifiers, or their performance in terms of coating water resistance and density is unsatisfactory. Therefore, there is a need in this field for modified epoxy resins that can overcome at least one of the aforementioned defects. Summary of the Invention

[0003] Based on the above requirements, this application provides a self-emulsifying modified epoxy resin, its preparation method, and its aqueous emulsion.

[0004] One aspect of this application provides a self-emulsifying modified epoxy resin comprising: a main chain including epoxy resin segments and segments derived from bi-carboxyl-terminated polyethylene glycol, side chains derived from unsaturated fatty acids, and side chains derived from olefin-containing copolymerizable monomers, wherein the olefin-containing copolymerizable monomers include one or more (meth)acrylate copolymerizable monomers.

[0005] The segments derived from the bilaterally carboxyl-terminated polyethylene glycol are grafted by a ring-opening reaction between the bilaterally carboxyl-terminated polyethylene glycol and the epoxy resin, and the molar ratio of the bilaterally carboxyl-terminated polyethylene glycol to the epoxy resin in the ring-opening reaction is 1:1 to 6, preferably 1:2 to 6.

[0006] Another aspect of this application provides a method for preparing a self-emulsifying modified epoxy resin, comprising the following steps:

[0007] (1) A ring-opening reaction is carried out between a double-carboxyl-terminated polyethylene glycol and an epoxy resin to obtain an epoxy resin comprising segments derived from the double-carboxyl-terminated polyethylene glycol; in the ring-opening reaction, the molar ratio of the double-carboxyl-terminated polyethylene glycol to the epoxy resin is 1:1 to 6.

[0008] (2) The epoxy resin comprising segments derived from bilaterally carboxyl-terminated polyethylene glycol is subjected to an esterification reaction with unsaturated fatty acids to obtain an epoxy ester.

[0009] (3) The epoxy ester and the copolymerizable monomer containing olefin bonds are subjected to free radical polymerization to obtain the self-emulsifying modified epoxy resin.

[0010] The self-emulsifying modified epoxy resin comprises: a main chain including epoxy resin segments and segments derived from polyethylene glycol with bilateral carboxyl groups, side chains derived from unsaturated fatty acids, and side chains derived from olefin-containing copolymerizable monomers; and the olefin-containing copolymerizable monomers include one or more (meth)acrylate copolymerizable monomers.

[0011] Another aspect of this application provides a self-emulsifying one-component aqueous epoxy resin emulsion comprising: water, and the self-emulsifying modified epoxy resin of the present invention or the self-emulsifying modified epoxy resin prepared according to the method of the present invention.

[0012] Another aspect of this application provides a method for preparing an aqueous modified epoxy resin emulsion, comprising: adding water to the self-emulsifying modified epoxy resin of the present invention or the self-emulsifying modified epoxy resin prepared according to the method of the present invention, and stirring.

[0013] Another aspect of this application provides the use of a self-emulsifying one-component aqueous epoxy resin emulsion as a coating.

[0014] The self-emulsifying modified epoxy resin of the present invention can spontaneously emulsify to form a one-component waterborne epoxy resin emulsion when mixed with water, without the need to add additional emulsifiers and / or curing agents; and the coating (or paint film) obtained from the waterborne emulsion of the present invention has one or more of the desired properties such as short surface drying time, good water resistance, good salt spray resistance, good adhesion and good flexibility. Detailed Implementation

[0015] The self-emulsifying modified epoxy resin of this application, its preparation method, and embodiments of its aqueous emulsion will be described in detail below. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand this application and is not intended to limit the subject matter of the claims.

[0016] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0017] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0018] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0019] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0020] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0021] Unless otherwise specified, the terms used herein have their usual understanding and meaning in the art.

[0022] Self-emulsifying modified epoxy resin

[0023] One aspect of this application provides a self-emulsifying modified epoxy resin comprising: a main chain including epoxy resin segments and segments derived from bi-carboxyl-terminated polyethylene glycol, side chains derived from unsaturated fatty acids, and side chains derived from olefin-containing copolymerizable monomers, wherein the olefin-containing copolymerizable monomers include one or more (meth)acrylate copolymerizable monomers.

[0024] The segments derived from the bilaterally carboxyl-terminated polyethylene glycol are grafted onto the epoxy resin through a ring-opening reaction, and the molar ratio of the bilaterally carboxyl-terminated polyethylene glycol to the epoxy resin in the ring-opening reaction is 1:1 to 6.

[0025] The self-emulsifying modified epoxy resin of the present invention can spontaneously emulsify to form a one-component aqueous emulsion when mixed with water, even in the absence of an emulsifier. Furthermore, the coating (or "film") obtained from this aqueous emulsion has one or more of the following desirable properties, preferably all of the following: short surface drying time, water resistance, salt spray resistance, good adhesion, and good flexibility. In addition, compared with the prior art, the self-emulsifying modified epoxy resin of the present invention eliminates the need for neutralization with acid or alkali media, avoiding the residue of neutralizing agents.

[0026] In some embodiments, preferably, in the ring-opening reaction, the molar ratio of the bi-carboxyl-terminated polyethylene glycol to the epoxy resin is 1:2 to 6, more preferably 1:3 to 6, even more preferably 1:4 to 6, and still more preferably 1:4. According to the present invention, the molar ratio of the bi-carboxyl-terminated polyethylene glycol to the epoxy resin can be 1:1, 1:2, 1:3, 1:4, 1:5, or 1:6, or any combination thereof.

[0027] The self-emulsifying modified epoxy resin molecules of the present invention have a high content of epoxy resin portion and a large molecular weight of modified epoxy resin, thereby improving the drying speed (e.g., surface drying speed) and density of the paint film (i.e., the macromolecular crosslinking network makes the paint film denser), and improving its salt spray resistance and / or water resistance, etc.

[0028] In this article, "self-emulsifying" means that when modified epoxy resin is mixed with water, the mixture can spontaneously emulsify to form an emulsion without the addition of emulsifiers or vigorous stirring. This property of modified epoxy resin is called "self-emulsifying function".

[0029] In this article, the term "bilaterally carboxyl-terminated polyethylene glycol" refers to carboxyl-functionalized polyethylene glycol (PEG) in which both ends of the polyethylene glycol molecular chain are capped with carboxyl-containing (-COOH) molecular moieties, wherein the carboxyl-containing molecular moieties are connected to the polyethylene glycol through linking groups (such as ester bonds).

[0030] In this article, "side chain" refers to a chemical group or polymer chain connected to the core of a molecule, also known as a "branch." In contrast to "side chain," the core of the molecule is called the "main chain," referring to the polymer chain with the most chain segments among those with side chain (branch) structures. A "segment" refers to a portion of the main chain consisting of two or more polymer chains derived from different monomers, with adjacent polymer chain portions connected at their ends. A "segment" can also be called a "block."

[0031] In this article, "grafting" means that a molecule acquires corresponding branches or segments through chemical bonding. Block copolymerization is a special case of graft copolymerization, in which the grafting points are located at both ends of the polymer chain segment; block copolymers have at least two types of segments on their main chain.

[0032] In this article, "modified epoxy resin" means epoxy resin whose molecular structure has been altered through chemical methods (e.g., grafting, polymerization, block polymerization, crosslinking, etc.); while the term "epoxy resin" used alone refers to unmodified epoxy resin raw materials.

[0033] In some embodiments, the weight-average molecular weight of the self-emulsifying modified epoxy resin is 20,000 to 100,000, preferably 50,000 to 90,000, and more preferably 65,000 to 90,000. The modified epoxy resin of the present invention has a relatively high molecular weight, thereby improving the drying speed (e.g., surface drying speed) of the coating film. In this document, the weight-average molecular weight (Mw) can be determined by gel permeation chromatography (GPC) according to GB / T 21863-2008.

[0034] [Segments derived from polyethylene glycol with bilateral carboxyl groups at the ends]

[0035] As described above, the main chain of the self-emulsifying modified epoxy resin of the present invention includes epoxy resin segments and segments derived from polyethylene glycol with bilateral carboxyl groups at the ends. The segments derived from polyethylene glycol with bilateral carboxyl groups at the ends are grafted onto the epoxy resin through a ring-opening reaction between the carboxyl groups of the polyethylene glycol with bilateral carboxyl groups at the ends.

[0036] The inventors noted that if polyethylene glycol (which only has hydroxyl groups) is directly reacted with epoxy resin in a ring-opening reaction, the reaction is difficult to occur and the reaction conditions are relatively harsh; however, the carboxylated polyethylene glycol of the present invention, due to its carboxyl groups, is easier to react with epoxy resin in a ring-opening reaction and the reaction conditions are also milder.

[0037] In some embodiments, preferably, the polyethylene glycol with carboxyl groups at both ends has 2 to 6 carboxyl groups, more preferably 3 to 6 carboxyl groups, and more preferably 4 to 6 carboxyl groups. It is understood that in this invention, the number of carboxyl groups in the polyethylene glycol with carboxyl groups at both ends can be 2, 3, 4, 5, or 6, or can be within the range of any two of the above values.

[0038] In this document, the term "bilaterally carboxyl-terminated polyethylene glycol" refers to a carboxyl-functionalized polyethylene glycol whose molecular chain is terminated at both ends by carboxyl-containing (-COOH) moieties, wherein the carboxyl-containing moieties are connected to the polyethylene glycol via linking groups (e.g., ester bonds). In this invention, the carboxyl-containing moieties are preferably connected to the polyethylene glycol via ester bonds.

[0039] The bilaterally carboxyl-terminated polyethylene glycol can be exemplarily represented by the following formula (I):

[0040]

[0041] Among them, L 1 and L 2 It is a residue moiety derived from a carboxyl-terminated modifier (such as a carboxylic acid or anhydride), which is linked to the polyethylene glycol backbone via an ester bond, and L 1 and L 2 They can be the same or different, but are preferably the same; n is an integer selected from 200 to 8000; p and q can be the same or different, and are each independently selected from an integer from 1 to 3.

[0042] In some embodiments, the bilaterally carboxyl-terminated polyethylene glycol has the same or different numbers of carboxyl groups at both ends, and the number of carboxyl groups is independently an integer selected from 1 to 3, preferably an integer selected from 2 to 3, and more preferably 2. Preferably, the bilaterally carboxyl-terminated polyethylene glycol has the same number of carboxyl groups at both ends, which is 2 to 3 carboxyl groups, preferably 2 carboxyl groups. For ease of understanding, the following exemplarily illustrates one embodiment of the bilaterally carboxyl-terminated polyethylene glycol, wherein two carboxyl groups are respectively present at both ends of the polyethylene glycol backbone:

[0043]

[0044] In some embodiments, the bi-carboxyl-terminated polyethylene glycol is obtained by esterification of polyethylene glycol with polyfunctional carboxylic acids and / or polyfunctional anhydrides.

[0045] In some embodiments, in the esterification reaction of polyethylene glycol with polyfunctional carboxylic acids and / or polyfunctional anhydrides, the molar ratio of the polyfunctional carboxylic acids and / or polyfunctional anhydrides based on carboxyl groups to the molar ratio of polyethylene glycol based on end groups reactive to carboxyl groups is 2 to 4:1, preferably 3 to 4:1, and more preferably 3:1.

[0046] In this document, "polyfunctional carboxylic acid" means a carboxylic acid having two or more carboxyl groups; "polyfunctional anhydride" means an anhydride formed by the dehydration of a polyfunctional carboxylic acid. In this invention, the polyfunctional anhydride can be formed by intermolecular dehydration of a carboxylic acid or by intramolecular dehydration of a carboxylic acid (i.e., dehydration between at least two carboxyl groups within a carboxylic acid molecule); preferably, it is formed by intramolecular dehydration of a carboxylic acid. A polyfunctional anhydride molecule may also have one or more free carboxyl groups. Furthermore, in this document, in expressions such as "molar amount based on carboxyl groups," for anhydrides, a group -C(O)-OC(O)- formed by the dehydration of two carboxyl groups is counted as two carboxyl groups.

[0047] In some embodiments, polyfunctional anhydrides are preferred. Preferably, the bi-carboxyl-terminated polyethylene glycol is obtained by reacting polyethylene glycol with a polyfunctional anhydride. In some embodiments, the polyfunctional carboxylic acid molecule corresponding to the polyfunctional anhydride may have 2 to 4 carboxyl groups; similarly, the corresponding terminology follows in other cases.

[0048] In some embodiments, the multifunctional anhydride includes trihydric anhydride, tetrahydric anhydride, or a mixture thereof, preferably trihydric anhydride. In some embodiments, the trihydric anhydride is preferably trimellitic anhydride. In some embodiments, the tetrahydric anhydride is preferably pyromellitic dianhydride. More preferably, the anhydride is trimellitic anhydride. The inventors have discovered that the bi-carboxyl-terminated polyethylene glycol prepared from the above-mentioned multifunctional carboxylic acids / anhydrides can increase the connection sites between polyethylene glycol and epoxy resin in the preparation of the modified epoxy resin of the present invention, resulting in a higher epoxy content and a larger molecular weight in the modified epoxy resin, and forming a branched structure in the modified epoxy resin, thereby helping to increase the emulsion solid content and reduce viscosity, improve the film density, and improve its performance.

[0049] Trimeric triglyceride is shown in the following formula:

[0050]

[0051] In some embodiments, the multifunctional anhydride may further include one or more of the following: methylhexahydrophthalic anhydride, maleic anhydride, methyltetrahydrophthalic anhydride, tung oil anhydride, hexahydrophthalic anhydride, polyazelic anhydride, polysebacalic anhydride, polyeicosanoic anhydride, cis-3,6-methylene-1,2,3,6-tetrahydrophthalic anhydride, glutaric anhydride, 1,4,5,6-tetrabromophthalic anhydride, and hexachloromethylenetetrahydrophthalic anhydride.

[0052] Preferably, the multifunctional anhydride is a trihydride, a tetrahydride, or a mixture thereof, and more preferably a trihydride.

[0053] In some embodiments, the content of polyfunctional carboxylic acid and / or polyfunctional anhydride residues in the self-emulsifying modified epoxy resin molecule of the present invention is 1 to 20 parts by weight, preferably 1 to 8 parts by weight, based on 100 parts by weight of epoxy resin segments. In this document, "epoxy resin segment" in "based on 100 parts by weight of epoxy resin segments" refers only to epoxy residues and does not include any side chain portions.

[0054] Polyethylene glycol (PEG) is an ethylene glycol polymer containing α,ω-terminated hydroxyl groups, and generally has the following molecular structure:

[0055]

[0056] Because its molecular structure contains ether bonds and hydroxyl functional groups, polyethylene glycol is hydrophilic and can react chemically with carboxyl groups, epoxy groups, and other groups.

[0057] In some embodiments, the polyethylene glycol used has a weight-average molecular weight of 200 to 8000, preferably 800 to 6000, more preferably 2000 to 6000, and even more preferably 2000 to 4000. For example, the weight-average molecular weight of the polyethylene glycol can be 200, 300, 400, 600, 800, 1000, 1500, 2000, 3000, 4000, 6000, or 8000, or its weight-average molecular weight can be within the range of any two of the above values. Selecting the above-mentioned polyethylene glycol is beneficial for the modified epoxy resin of the present invention to have appropriate hydrophilicity and achieve self-emulsification, and ensures that the coating film has ideal water resistance.

[0058] Polyethylene glycol (PEG) is commercially available. In some embodiments, the PEG used is selected from one or more of the following: PEG-200, PEG-300, PEG-400, PEG-600, PEG-800, PEG-1000, PEG-1500, PEG-2000, PEG-3000, PEG-4000, PEG-6000, and PEG-8000. PEG-800-6000 is preferred, and PEG-2000-6000 is more preferred, for example, PEG-2000, PEG-3000, PEG-4000, and PEG-6000. As those skilled in the art will understand, the numerical part in the name of the aforementioned commercially available polyethylene glycol products corresponds to the average molecular weight (especially the weight-average molecular weight) of the polyethylene glycol.

[0059] In some embodiments, the content of polyethylene glycol residues in the self-emulsifying modified epoxy resin molecule of the present invention is 5 to 200 parts by weight, preferably 10 to 120 parts by weight, based on 100 parts by weight of epoxy resin segments.

[0060] The epoxy resin used in this invention is an epoxy resin having at least two epoxy groups per molecule. Suitable epoxy resins include, for example: phenolic epoxy resins such as phenolic resin and cresol phenolic resin; bisphenol epoxy resins such as bisphenol A epoxy resin and bisphenol F epoxy resin; aromatic glycidylamine epoxy resins such as N,N-diglycidylaniline, N,N-diglycidyltoluidine, diaminodiphenylmethane glycidylamine, and aminophenol glycidylamine; hydroquinone epoxy resin, biphenyl epoxy resin, diphenylethylene epoxy resin, and triphenolmethane epoxy resin. The epoxy resins include triphenol propane-type epoxy resins, alkyl-modified triphenol methane-type epoxy resins, epoxy resins containing triazine cores, dicyclopentadiene-modified phenol-type epoxy resins, naphthol-type epoxy resins, naphthol-type epoxy resins, phenol aralkyl-type epoxy resins having a phenylene and / or biphenylene skeleton, naphthol aralkyl-type epoxy resins having a phenylene and / or biphenylene skeleton, and alicyclic epoxy resins such as vinylcyclohexene dioxide, dicyclopentadiene oxide, and alicyclic diethio-adipate esters, etc., and alicyclic epoxy resins such as cyclohexene dioxide, dicyclopentadiene oxide, and alicyclic diethio-adipate esters. According to the present invention, an epoxy resin may be used alone or in a mixture of two or more types.

[0061] Preferably, the epoxy resin is a bisphenol type epoxy resin, more preferably a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a mixture thereof.

[0062] In some embodiments, the number-average molecular weight (Mn) of the epoxy resin is 400–3000, preferably 500–1500. In this document, the number-average molecular weight (Mn) was determined by gel permeation chromatography (GPC) according to GB / T 21863-2008.

[0063] In some embodiments, the epoxy value of the epoxy resin is 0.04–0.54 eq / 100g, preferably 0.1–0.3 eq / 100g. In this document, the epoxy value is determined according to GB / T 4612-2008.

[0064] According to the present invention, using an epoxy resin having the above-mentioned number-average molecular weight and / or epoxy value allows for a suitable crosslinking density after the self-emulsifying modified epoxy resin of the present invention forms a film, thereby achieving a good balance between rigidity and flexibility in the coating film. Furthermore, using such an epoxy resin also provides an ideal number of acrylic modification sites, which is beneficial for performance improvement.

[0065] [Derived from the side chains of unsaturated fatty acids]

[0066] The self-emulsifying modified epoxy resin of the present invention also has side chains derived from unsaturated fatty acids, which are grafted by esterification reaction of unsaturated fatty acids with epoxy resin including segments of polyethylene glycol derived from bilateral carboxyl groups.

[0067] In this esterification reaction, the amounts of unsaturated fatty acids and epoxy groups added are conventionally determined by those skilled in the art. In some embodiments, the molar ratio of unsaturated fatty acids (based on carboxyl groups) to epoxy groups in the esterification reaction is 1 to 3:1, preferably 2:1.

[0068] Unsaturated fatty acids are conventionally selected by those skilled in the art. The unsaturated fatty acids used in this invention are chain fatty acids having 10 to 30, preferably 12 to 25 carbon atoms and at least one double bond, more preferably unsaturated fatty acids having 18 carbon atoms. Introducing such side chains provides the self-emulsifying epoxy resin of this invention with suitable flexibility and unsaturated double bonds that can be used for subsequent oxidative self-crosslinking. In some embodiments, the unsaturated fatty acid is selected from one or more of the following: oleic acid, linoleic acid, linolenic acid, ricinoleic acid, tung oil acid, soybean oil acid, myristoleic acid, octadecanoic acid, arachidonic acid, eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid.

[0069] In some embodiments, the content of unsaturated fatty acid residues in the self-emulsifying modified epoxy resin molecule of the present invention is 20 to 120 parts by weight, preferably 80 to 100 parts by weight, based on 100 parts by weight of epoxy resin segments.

[0070] [Derived from side chains of copolymerizable monomers containing olefin bonds]

[0071] The self-emulsifying modified epoxy resin of the present invention further comprises side chains derived from olefin-containing copolymerizable monomers. These side chains are grafted onto the modified epoxy resin by polymerization of the olefin-containing copolymerizable monomers with segments of polyethylene glycol derived from bi-carboxyl-terminated groups and side chains derived from unsaturated fatty acids. The olefin-containing copolymerizable monomers include one or more (meth)acrylate copolymerizable monomers. Preferably, the side chains are grafted onto the modified epoxy resin by random copolymerization of one or more olefin-containing copolymerizable monomers.

[0072] In this article, the term "(meth)acrylate comonomer" means acrylate comonomer and methacrylate comonomer.

[0073] In some embodiments, the (meth)acrylate comonomer may be one or more (meth)acrylates of branched or straight-chain alcohols having 1 to 10 carbon atoms. For example, the (meth)acrylate comonomer may be selected from one or more of the following: methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, nonyl methacrylate, and decyl methacrylate.

[0074] In some embodiments, the (meth)acrylate comonomer comprises at least 50% by weight of all olefin-containing comonomers, preferably 50-75% by weight, more preferably 53-71% by weight, and even more preferably 53-66% by weight.

[0075] In some embodiments, the olefin-containing copolymerizable monomer further includes one or more vinyl polymerizable monomers selected from: vinyl aromatics having up to 20 carbon atoms, olefinically unsaturated nitrile compounds, halogenated or non-halogenated olefins having 2 to 6 carbon atoms, and vinyl ethers of alcohols having 1 to 10 carbon atoms. Preferably, the halogenated or non-halogenated olefin having 2 to 6 carbon atoms is ethylene or a haloethylene. Preferably, the halogenated olefin is a chlorinated, fluorinated, or bromine-substituted olefin. Preferably, the vinyl ether of an alcohol having 1 to 10 carbon atoms is a vinyl ether of an alcohol having 1 to 4 carbon atoms.

[0076] Preferably, in some embodiments, the vinyl copolymerizable monomer is selected from one or more of the following: styrene, vinyltoluene, α-methylstyrene and p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, vinyl methyl ether and vinyl isobutyl ether; more preferably, styrene, vinyltoluene or combinations thereof.

[0077] In some embodiments, the olefin-containing copolymerizable monomer further includes (meth)acrylamide.

[0078] In some embodiments, the olefin-containing copolymerizable monomer is selected from (meth)acrylate copolymerizable monomers, vinyl copolymerizable monomers, and combinations thereof. Preferably, in some embodiments, the olefin-containing copolymerizable monomer comprises a mixture of (meth)acrylate and styrene.

[0079] Graft polymerization of (meth)acrylate monomers with epoxy resins that have undergone ring-opening esterification of unsaturated fatty acids is beneficial to improving the corrosion resistance, water resistance, storage stability, and mechanical properties of the modified epoxy resin of this invention.

[0080] In some embodiments, the content of the olefin-containing copolymerizable monomer residues in the self-emulsifying modified epoxy resin molecule of the present invention is 30 to 300 parts by weight, preferably 80 to 120 parts by weight, based on 100 parts by weight of epoxy resin segments.

[0081] In some embodiments, the self-emulsifying modified epoxy resin of the present invention is obtained by the following steps:

[0082] (1) A ring-opening reaction is carried out between a double-carboxyl-terminated polyethylene glycol and an epoxy resin to obtain an epoxy resin comprising segments derived from the double-carboxyl-terminated polyethylene glycol; in the ring-opening reaction, the molar ratio of the double-carboxyl-terminated polyethylene glycol to the epoxy resin is 1:1 to 6.

[0083] (2) The epoxy resin comprising segments derived from bilaterally carboxyl-terminated polyethylene glycol is subjected to an esterification reaction with unsaturated fatty acids to obtain an epoxy ester.

[0084] (3) The epoxy ester is subjected to free radical polymerization with an olefin-containing copolymerizable monomer to obtain the self-emulsifying modified epoxy resin; wherein the olefin-containing copolymerizable monomer includes one or more (meth)acrylate copolymerizable monomers.

[0085] The reaction conditions (e.g., atmosphere, temperature, catalyst, initiator, etc.) involved in the above steps are subject to the corresponding descriptions in the Methods section below.

[0086] The self-emulsifying modified epoxy resin of the present invention can be readily used to prepare self-emulsifying single-component aqueous epoxy resin emulsions. Furthermore, because the modified epoxy resin of the present invention has a high epoxy content in its molecules and can possess a certain degree of branching (or branched structure), it significantly overcomes the problem of low crosslinking density after film formation in existing single-component aqueous epoxy resin emulsions due to the lack of a curing agent. Therefore, its coating exhibits good resistance to adverse environmental conditions (e.g., humidity, salt spray).

[0087] The various descriptions of the self-emulsifying modified epoxy resin of the present invention in the foregoing are applicable to the descriptions of the corresponding contents / features in the preparation method below.

[0088] Method for preparing self-emulsifying modified epoxy resin

[0089] Another aspect of this application provides a method for preparing a self-emulsifying modified epoxy resin, comprising the following steps:

[0090] (1) A ring-opening reaction is carried out between a bi-carboxyl-terminated polyethylene glycol and an epoxy resin to obtain an epoxy resin comprising segments derived from the bi-carboxyl-terminated polyethylene glycol; wherein the molar ratio of the bi-carboxyl-terminated polyethylene glycol to the epoxy resin in the ring-opening reaction is 1:1 to 6.

[0091] (2) The epoxy resin comprising segments derived from bilaterally carboxyl-terminated polyethylene glycol is subjected to an esterification reaction with unsaturated fatty acids to obtain an epoxy ester.

[0092] (3) The epoxy ester and the copolymerizable monomer containing olefin bonds are subjected to free radical polymerization to obtain the self-emulsifying modified epoxy resin.

[0093] The self-emulsifying modified epoxy resin comprises: a main chain including epoxy resin segments and segments derived from polyethylene glycol with bilateral carboxyl groups, side chains derived from unsaturated fatty acids, and side chains derived from olefin-containing copolymerizable monomers; and the olefin-containing copolymerizable monomers include one or more (meth)acrylate copolymerizable monomers.

[0094] Unless otherwise specified or defined in this document, the operation is performed at room temperature and normal pressure.

[0095] The following will describe in detail the various steps of the preparation method of the present invention.

[0096]

Step (1)

[0097] As described above, in step (1), the bi-carboxyl-terminated polyethylene glycol is subjected to a ring-opening reaction with the epoxy resin to obtain an epoxy resin comprising segments derived from the bi-carboxyl-terminated polyethylene glycol; in the ring-opening reaction, the molar ratio of the bi-carboxyl-terminated polyethylene glycol to the epoxy resin is 1:1 to 6, preferably 1:2 to 6.

[0098] The reaction in step (1) is carried out under an inert atmosphere. The inert atmosphere used herein is known in the art and can be conventionally selected. In some embodiments, the inert atmosphere is a nitrogen atmosphere.

[0099] In some embodiments, the reaction in step (1) is carried out at a temperature of 90–150°C. As can be seen from the reaction temperature, the reaction conditions for this step are relatively mild (in contrast, a similar ring-opening reaction with polyethylene glycol typically requires a reaction temperature above 200°C). In some embodiments, in step (1), the acid value is measured during the reaction, and the reaction reaches its endpoint when the acid value is <5 mg KOH / g. In this document, the acid value is measured by chemical titration, where the titrant is an ethanolic solution of potassium hydroxide or sodium hydroxide. In some embodiments, the reaction in step (1) is carried out for approximately 1–4 hours.

[0100] In some implementations, for example, step (1) may be performed as follows:

[0101]

[0102] in

[0103] R1 means:

[0104]

[0105] R2 means:

[0106]

[0107] In the above reaction, due to steric hindrance, it is difficult for both epoxy groups to react simultaneously. Therefore, in actual reaction, one epoxy group will react preferentially. Thus, this reaction can yield a product with a carboxylated molecule at one end and an epoxy group at the other end without the need for a protecting group. Moreover, the above ring-opening reaction does not require the introduction of Lewis acids or other substances into the system, so there is no risk of residual substances leading to product performance degradation.

[0108] In some embodiments, the bi-carboxyl-terminated polyethylene glycol is obtained by reacting polyethylene glycol with a polyfunctional carboxylic acid and / or a polyfunctional anhydride; wherein the molar ratio of the polyfunctional carboxylic acid and / or polyfunctional anhydride based on the number of carboxyl groups to the molar ratio of polyethylene glycol based on the number of carboxyl-reactive end groups is 2 to 4:1, preferably 3 to 4:1. Suitable polyethylene glycols and acids / anhydrides are as described above. In some embodiments, for example, the bi-carboxyl-terminated polyethylene glycol can be obtained by the following reaction:

[0109]

[0110] In the method of this invention, when introducing polyethylene glycol (PEG) segments, a ring-opening reaction is carried out between PEG with bilaterally carboxyl-terminated segments and epoxy resin. Compared to directly using PEG, acid anhydride, and epoxy resin for a ring-opening reaction, the reaction is relatively easier to occur, and therefore the reaction conditions are milder. Simultaneously, using PEG with bilaterally carboxyl-terminated segments eliminates side reactions between PEG and epoxy resin, which is beneficial for controlling the molecular structure of the final product, eliminating system gelation, and improving system compatibility and stability. Furthermore, the ring-opening reaction of this invention does not require Lewis acids as catalysts, thereby eliminating the possibility of acid residue deteriorating coating performance and the significant challenges to production equipment posed by the use of acids.

[0111] In some embodiments, when trimellitic anhydride is used, the preferred molar ratio of trimellitic anhydride to polyethylene glycol is 2:1.

[0112] In some embodiments, the amount of polyfunctional carboxylic acid and / or polyfunctional anhydride is 1 to 20 parts by weight, preferably 1 to 8 parts by weight, based on 100 parts by weight of epoxy resin. In some embodiments, the amount of polyethylene glycol in step (1) is 5 to 200 parts by weight, preferably 10 to 120 parts by weight, based on 100 parts by weight of epoxy resin. As defined above, “epoxy resin” here refers to unmodified epoxy resin raw material; unless otherwise specified below, the same meaning applies.

[0113] In some embodiments, the reaction to obtain bilaterally carboxyl-terminated polyethylene glycol is carried out at a temperature of 80–150°C, preferably 90–130°C. In some embodiments, the reaction is carried out by first heating the polyethylene glycol to the desired reaction temperature, and then adding a polyfunctional carboxylic acid and / or anhydride under a nitrogen atmosphere to initiate the reaction. In some embodiments, the acid value of the system is measured during the reaction to confirm the reaction endpoint. Specifically, if the anhydride is trimellitic anhydride, the reaction reaches its endpoint when the acid value decreases to two-thirds of its initial value; if the anhydride is tetracarboxylic anhydride, the reaction reaches its endpoint when the acid value decreases to three-quarters of its initial value. In some embodiments, the reaction is carried out at a temperature of 90–130°C for 1–3 hours.

[0114]

Step (2)

[0115] As described above, in step (2), the epoxy resin comprising segments derived from bi-carboxyl-terminated polyethylene glycol is subjected to an esterification reaction with an unsaturated fatty acid to obtain an epoxy ester. Suitable unsaturated fatty acids are described above.

[0116] In some embodiments, the amount of unsaturated fatty acid used in step (2) is 20 to 120 parts by weight, preferably 80 to 100 parts by weight, based on 100 parts by weight of epoxy resin.

[0117] In some embodiments, the esterification reaction in step (2) is carried out at a temperature of 140–240°C. In some embodiments, it is preferable to first preheat the unsaturated fatty acid to a temperature of 140–170°C, then add the modified epoxy resin obtained in step (1), and heat the reaction mixture to a temperature of 180–240°C to carry out the esterification reaction to obtain the epoxy ester. In some embodiments, the acid value is measured during the reaction, and the reaction reaches its endpoint when the acid value is <5 mg KOH / g. In some embodiments, the esterification reaction in step (2) is carried out for 4–10 hours.

[0118] The reaction in step (2) is carried out in the presence of a catalyst. A suitable catalyst is at least one substance selected from the following: metal oxides, such as calcium oxide, lead oxide; hydroxides of alkali metals or alkaline earth metals, such as lithium hydroxide; organometallic compounds, such as lithium naphthenate, calcium naphthenate, dibutyltin, stannous octoate, monobutyltin oxide; and phosphine compounds, such as triphenylphosphine.

[0119] In some embodiments, the amount of catalyst used in step (2) is 0.1 to 3 parts by weight, preferably 0.5 to 2 parts by weight, based on 100 parts by weight of epoxy resin.

[0120] In some implementations, for example, step (2) may be performed as follows:

[0121]

[0122] in:

[0123] The definitions of R1 and R2 are the same as above.

[0124] R3 indicates:

[0125]

[0126] In some embodiments, preferably, after the esterification reaction in step (2) is completed, an organic solvent is added to make the solid content of the epoxy ester 50% to 80%, which can avoid the gelation phenomenon that occurs in subsequent steps (e.g., step (3) which will be described in detail below) due to excessive system viscosity.

[0127] In some embodiments, the organic solvent is selected from one or more of the following: ketones, aromatic hydrocarbons, aliphatic hydrocarbons, ethers, esters, alcohols, and petroleum-based solvents; preferably, the organic solvent is a mixture of alcohol and ether, more preferably a mixture of alcohol and diol ether, and even more preferably, the volume ratio of the alcohol to the ether is 2:3 to 3:2.

[0128] In some embodiments, the ketone is selected from one or more of methyl ethyl ketone, cyclohexanone, isophorone, and diacetone alcohol. In some embodiments, the aromatic hydrocarbon is selected from one or more of toluene, xylene, trimethylbenzene, and tetramethylbenzene. In some embodiments, the ether is selected from one or more of propylene glycol methyl ether, ethylene glycol monobutyl ether, and triethylene glycol monoethyl ether. In some embodiments, the ester is selected from one or more of ethyl acetate, butyl acetate, dimethyl adipate, dimethyl succinate, dimethyl glutarate, dimethyl ethylene glycol, diethyl ethylene glycol, dimethyl propylene glycol, dipropylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate. In some embodiments, the alcohol is selected from one or more of ethanol, propanol, n-butanol, isopropanol, ethylene glycol, and propylene glycol. In some embodiments, the aliphatic hydrocarbon is selected from octane or cyclohexane. In some embodiments, the petroleum-based solvent is selected from one or more of petroleum ether, naphtha, hydrogenated naphtha, and solvent naphtha.

[0129] In some embodiments, the organic solvent is preferably a mixture of n-butanol and propylene glycol methyl ether or ethylene glycol monobutyl ether, wherein the volume ratio of alcohol to ether is 2:3 to 3:2.

[0130]

Step (3)

[0131] As described above, in step (3), the epoxy ester is subjected to free radical polymerization, particularly random copolymerization, with an olefin-containing copolymerizable monomer to obtain the self-emulsifying modified epoxy resin; wherein the olefin-containing copolymerizable monomer includes one or more (meth)acrylate copolymerizable monomers. Suitable olefin-containing copolymerizable monomers are described above.

[0132] In some embodiments, the amount of the olefin-containing copolymerizable monomer residues is 30 to 300 parts by weight, preferably 80 to 120 parts by weight, based on 100 parts by weight of epoxy resin.

[0133] Step (3) is carried out in the presence of an initiator. Examples of suitable initiators are peroxides (including alkyl hydroperoxides and aryl hydroperoxides, alkyl peroxides and aryl peroxides), peresters, persulfates, perborates, percarbonates, azo compounds, etc. Some specific examples include the following initiators: for example, hydrogen peroxide, di(tert-butyl)peroxide, diethyl tert-butyl peroxyacetate, tert-butyl peroctanoate, tert-butyl peroxyisobutyrate, 1,1-di(tert-butyl peroxy)cyclohexane, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl perbenzoate, tert-butyl peroxyneopentate, tert-pentyl peroxyneopentate, tert-butyl peroxy-2-ethylhexanoate, 1,1-di(tert-pentyl peroxy)cyclohexane, lauroyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), etc. These initiators can be used alone or in mixtures of two or more components.

[0134] In some embodiments, the amount of initiator in step (3) is 0.5 to 8 parts by weight, preferably 2 to 6 parts by weight, based on 100 parts by weight of epoxy resin.

[0135] In some embodiments, the free radical polymerization reaction in step (3) is carried out at a temperature of 110–130°C. In some embodiments, it is preferable to uniformly mix the copolymerizable monomer and the initiator and add them dropwise to the epoxy ester obtained in step (2). Adding the mixed monomers dropwise to the epoxy ester can better improve the grafting rate and monomer conversion rate, and can better control the molecular structure, avoiding monomer self-polymerization, gelation, or explosive polymerization. In some embodiments, the above reaction is carried out for 3–5 hours.

[0136] In some embodiments, it is preferable to maintain the system temperature at 120–140°C for 4–6 hours after the free radical polymerization reaction in step (3). This can better improve the monomer conversion rate and allow unreacted monomers to polymerize, reducing residual monomers.

[0137] In some implementations, for example, step (3) may be performed as follows (where the definitions of the various groups are the same as above):

[0138]

[0139] As will be understood by those skilled in the art, in the exemplary step (3) above, the three exemplary olefin-containing copolymerizable monomers (i.e., methyl methacrylate, styrene, and butyl acrylate) are polymerized in a random copolymerization manner to form side chains; in other words, the three monomers are connected in a random order during polymerization, and are not limited to those shown. Furthermore, the side chains can be grafted onto any active site on the epoxide ester; as shown in the reaction formula above, the wavy lines represent side chains that are extended or grafted onto exemplary sites on the main chain in a random copolymerization manner.

[0140] In some embodiments, the self-emulsifying modified epoxy resin of the present invention can be prepared from the following components:

[0141] (A) 100 parts by weight of epoxy resin,

[0142] (B) 5-200 parts by weight, preferably 10-120 parts by weight of polyethylene glycol,

[0143] (C) 1 to 20 parts by weight, preferably 1 to 8 parts by weight of polyfunctional carboxylic acids and / or polyfunctional anhydrides.

[0144] (D) 20-120 parts by weight, preferably 80-100 parts by weight, of unsaturated fatty acids having 10-30 carbon atoms.

[0145] (E) 30 to 300 parts by weight, preferably 80 to 120 parts by weight of olefin-containing copolymerizable monomers.

[0146] (F) 0.1 to 3 parts by weight, preferably 0.5 to 2 parts by weight, of a catalyst, and

[0147] (G) 0.5 to 8 parts by weight, preferably 2 to 6 parts by weight of initiator.

[0148] Self-emulsifying single-component waterborne epoxy resin emulsion and its preparation method

[0149] Another aspect of this application provides a self-emulsifying one-component aqueous epoxy resin emulsion comprising: water and the self-emulsifying modified epoxy resin of the present invention or a self-emulsifying modified epoxy resin prepared according to the method of the present invention.

[0150] The self-emulsifying modified epoxy resin of the present invention can spontaneously emulsify to produce an emulsion after being mixed with water without the need for an emulsifier; and the resulting aqueous emulsion is a one-component aqueous epoxy resin emulsion.

[0151] It is known that two-component epoxy resin emulsions require the assistance of a curing agent to form a film, while the film-forming process of one-component epoxy resin emulsions does not require the participation of a curing agent. Therefore, in the preparation of coatings using existing one-component aqueous emulsions, the lack of a curing agent results in low crosslinking density after film formation, leading to poor coating density and poor resistance. The one-component aqueous emulsion obtained from the self-emulsifying modified epoxy resin of this invention overcomes the above-mentioned defects. It can dry and form a film relatively quickly, and the film layer (or paint film) is dense, flexible, and possesses significantly improved acid and alkali resistance and good resistance.

[0152] As described above, the waterborne epoxy resin emulsion of this application is a self-emulsifying one-component modified epoxy resin emulsion; it does not contain emulsifiers, curing agents and / or cosolvents, etc.

[0153] In some embodiments, the solid content of the waterborne epoxy resin emulsion is 20-55%, preferably 30-45%, based on the total weight of the waterborne emulsion. In some embodiments, the viscosity of the waterborne epoxy resin emulsion of the present invention is 20-120 seconds, preferably 30-80 seconds, determined according to GB / T1725-93 using the Foremost viscometer method. Unless otherwise specified, all viscosities mentioned herein are determined according to GB / T1725-93 using the Foremost viscometer method. Clearly, the waterborne emulsion of the present invention has a high solid content and low viscosity, therefore, when used as a coating, it is easy to apply and has a faster surface drying time.

[0154] In some implementations, the pH of the aqueous epoxy resin emulsion is 7 to 9.

[0155] In some embodiments, the aqueous epoxy resin emulsion may also include other suitable resins, provided they are compatible with the emulsion system of the present invention.

[0156] In some embodiments, the aqueous epoxy resin emulsion may also include other components, such as driers, defoamers, leveling agents, ultraviolet absorbers, antioxidants, etc.

[0157] Another aspect of this application provides a method for preparing the above-mentioned aqueous epoxy resin emulsion, comprising: adding water to the self-emulsifying modified epoxy resin of the present invention or the self-emulsifying modified epoxy resin prepared according to the method of the present invention, and stirring.

[0158] In some embodiments, after the self-emulsifying modified epoxy resin of the present invention is prepared, preferably after the heat preservation in step (3) is completed, water is immediately added to the system for dispersion to obtain an aqueous epoxy resin emulsion. Preferably, water is added at a temperature of 30–50°C.

[0159] In this invention, there are no special requirements for stirring when preparing the emulsion, and those skilled in the art can carry it out in a conventional manner.

[0160] use

[0161] Furthermore, this application also provides the use of the self-emulsifying one-component aqueous epoxy resin emulsion of the present invention and the self-emulsifying one-component aqueous epoxy resin emulsion prepared according to the method of the present invention as a coating. When the self-emulsifying one-component aqueous epoxy resin emulsion of the present invention is used as a coating, no curing agent is required, nor is a complex and cumbersome construction process necessary, and it has a long operating window. Moreover, after the emulsion is directly applied to the substrate surface, it reaches surface dryness in 10-20 minutes and exhibits excellent water resistance and flexibility.

[0162] In this regard, the self-emulsifying one-component waterborne epoxy resin emulsion of the present invention can be used as a film coating agent, leather coating agent, wood coating, industrial coating, etc. In particular, the self-emulsifying one-component waterborne epoxy resin emulsion of the present invention is suitable as a coating for various petroleum equipment, chemical equipment, power equipment, hydraulic equipment, fire-fighting equipment; large and medium-sized machinery and equipment such as railways, bridges, pipelines, automobile parts, cranes, excavators, and machine tools; and rust-proof coating for castings, forgings, and other metals.

[0163] When applied as a coating, the self-emulsifying one-component aqueous epoxy resin emulsion of the present invention can be applied to the substrate by conventional methods known to those skilled in the art, such as spraying, smearing, scraping, brushing, rolling, or pouring. In use, the coating is applied to the substrate to be coated to the desired thickness and allowed to dry naturally at room temperature or at a low temperature. This operation can be repeated once or more.

[0164] Example

[0165] The present invention will be further described below with reference to embodiments:

[0166] 1. Materials

[0167] (1) Acid anhydride:

[0168] Trimeric triglyceride: white flakes, purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0169] (2) Polyethylene glycol (PEG):

[0170] Polyethylene glycol PEG2000: average molecular weight 2000, purchased from Jinan Quanchi New Materials Co., Ltd.;

[0171] Polyethylene glycol PEG4000: average molecular weight 4000, purchased from Jinan Quanchi New Materials Co., Ltd.

[0172] (3) Epoxy resin

[0173] Bisphenol A type epoxy resin 901: epoxy value is 0.21 eq / 100g, number average molecular weight Mn is 1000, purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd.

[0174] Bisphenol A type epoxy resin E-12: epoxy value 0.12eq / 100g, number average molecular weight Mn is 1500, purchased from Guangzhou Yihuisheng Chemical Co., Ltd.

[0175] Bisphenol A type epoxy resin E-51: epoxy value 0.51eq / 100g, number average molecular weight Mn 510, purchased from Guangzhou Yihuisheng Chemical Co., Ltd.

[0176] (4) Unsaturated fatty acids (USFA)

[0177] Linolenic acid: purchased from Anhui Ruifende Oil Deep Processing Co., Ltd.

[0178] (5) Alkenyl bond unsaturated monomers

[0179] Ethyl acrylate: purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0180] Methyl methacrylate: purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0181] Butyl acrylate: purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0182] (6) Other copolymerizable monomers:

[0183] Styrene: Purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0184] (7) Catalyst:

[0185] Stannous octoate: Purchased from Aladdin Reagents (Shanghai) Co., Ltd.

[0186] Monobutyltin oxide: purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0187] Triphenylphosphine: Purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0188] (8) Initiator:

[0189] Benzoyl peroxide (BPO): Purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0190] (9) Metal ion drying agent: purchased from Tianjin Shangde Xinjia Trading Co., Ltd.

[0191] (10) Defoamer: purchased from BYK Chemical GmbH, Germany

[0192] (11) Wetting agent: purchased from BYK Chemical GmbH, Germany

[0193] Unless otherwise specified, all of the above materials are ordinary commercially available products.

[0194] 2. Testing Methods

[0195] Solid content: determined according to GB / T 1725-2007.

[0196] Molecular weight: determined by gel permeation chromatography (GPC) according to GB / T 21863-2008, the result is the weight-average molecular weight.

[0197] Viscosity: Measured using a Forehead 4 cup according to GB / T 1723-93.

[0198] Surface drying time: determined according to GB / T1728-79, by method B of the surface drying time determination method – the finger touch method.

[0199] Water resistance and whitening degree: Immerse the test sample in deionized water at room temperature for 72 hours, and visually evaluate the degree of whitening of the sample.

[0200] Impact strength: in accordance with GB / T 1732-1993, wherein the scale on the slide where the hammer falls is 50cm.

[0201] Adhesion: Determined by cross-cut test according to GB / T9286-1998. Grade 0 indicates that the cut edge is completely smooth with no peeling. Grade 1 indicates that there is a small amount of coating peeling at the cut intersection, but the affected cross-cut area cannot be significantly greater than 5%. Grade 2 indicates that there is coating peeling at the cut intersection and / or along the cut edge, and the affected cross-cut area is significantly greater than 5% but not significantly greater than 15%.

[0202] Flexibility (bending resistance): determined according to GB / T 1731-1993.

[0203] Salt spray resistance: determined according to GB / T 1771-1991.

[0204] 3. Preparation of trimellitic anhydride-modified polyethylene glycol (also known as carboxyl-terminated polyethylene glycol or carboxylated polyethylene glycol)

[0205] (1) Preparation of bilaterally carboxyl-terminated polyethylene glycol 2000

[0206] Polyethylene glycol 2000 was dried in an oven at 85°C for 12 hours. 200g of the dried PEG2000 was transferred to a four-necked round-bottom flask, heated to 120°C, and the nitrogen flow rate was controlled using a bubbler. After purging with nitrogen for a short time, 40g of trimellitic anhydride was added. The mixture was mechanically stirred at 70 rpm, and the reaction continued for a certain time while maintaining a nitrogen flow. The acid value of the reaction system was measured until it decreased to two-thirds of its initial value, reaching the reaction endpoint, thus obtaining bi-carboxyl-terminated polyethylene glycol 2000.

[0207] (2) Preparation of bilaterally carboxyl-terminated polyethylene glycol 4000

[0208] Polyethylene glycol 4000 was dried in an oven at 85°C for 12 hours. 400g of the dried polyethylene glycol 4000 was transferred to a four-necked round-bottom flask, heated to 120°C, and the nitrogen flow rate was controlled using a bubbler. After purging with nitrogen for a short time, 40g of trimellitic anhydride was added. The mixture was mechanically stirred at 70 rpm, and the reaction continued for a certain time while maintaining a nitrogen flow. The acid value of the reaction system was measured until it decreased to two-thirds of its initial value, reaching the reaction endpoint. This yielded polyethylene glycol 4000 with double carboxyl-terminated ends.

[0209] 4. Preparation of modified epoxy resins and their aqueous emulsions

[0210] Example 1

[0211] Add 240g of bi-carboxyl-terminated polyethylene glycol 2000 (prepared as described above) to a 1000ml four-necked round-bottom flask, raise the temperature to 110℃, then add 400g of bisphenol A type epoxy resin 901 and raise the temperature to 140℃. After reacting for 1 hour, start measuring the acid value. Take a sample every hour to measure the acid value until the acid value is <10mg KOH / g, at which point the reaction has reached its endpoint.

[0212] Then, add 336g of linolenic acid to the four-necked flask and heat to 150℃. After dissolving and stirring until homogeneous and transparent, raise the temperature to 200℃ and add 4g of stannous octoate. Take a sample every hour to measure the acid value until the acid value is <5mg KOH / g, indicating that the esterification reaction is complete. Cool down and add a mixture of n-butanol and propylene glycol methyl ether, with a n-butanol:propylene glycol methyl ether (v / v) ratio of 1:1, to control the solid content of the epoxy ester to 60%.

[0213] 250g of the above epoxy ester was added to a 1000mL three-necked flask and heated to 120℃. 40g of styrene, 35g of ethyl acrylate, 15g of butyl acrylate, and 4g of benzoyl peroxide (BPO) were weighed and mixed thoroughly. This mixture was then added dropwise to the epoxy ester. The reaction temperature was 120℃, and the reaction time was 4 hours. After the reaction was complete, the temperature was raised to 130℃ and maintained for 5 hours. The molecular weight of the resulting modified epoxy resin was determined and recorded in Table 1 below.

[0214] After the heat preservation is completed, the temperature is lowered to 40℃, water is added for dispersion, and a milky white waterborne epoxy resin emulsion that cures at room temperature is obtained with a solid content of 41% and a viscosity of 42s at Forte 4 cup.

[0215] Example 2

[0216] Add 200g of carboxyl-terminated polyethylene glycol 2000 (prepared as described above) to a 1000ml four-necked round-bottom flask, raise the temperature to 110℃, then add 200g of bisphenol A epoxy resin 901 and 200g of bisphenol A epoxy resin E12, raise the temperature to 120℃, and start measuring the acid value after reacting for 1 hour. Take a sample every hour to measure the acid value until the acid value is <10mg KOH / g, at which point the reaction has reached its endpoint.

[0217] Then, add 270g of linolenic acid to the four-necked flask and heat to 150℃. After dissolving and stirring until it becomes clear, raise the temperature to 200℃ and add 4g of triphenylphosphine. Take a sample every hour to measure the acid value until the acid value is <5mg KOH / g, indicating that the esterification reaction is complete. Cool down and add a mixture of n-butanol and propylene glycol methyl ether, with a n-butanol:propylene glycol methyl ether (v / v) ratio of 2:3, to control the solid content of the epoxy ester to 60%.

[0218] Take 250g of the above epoxy ester and place it in a 1000mL three-necked flask. Heat the flask to 110℃. Weigh out 25g of styrene, 15g of methyl methacrylate, 20g of butyl acrylate, 12.5g of isooctyl acrylate, and 5g of benzoyl peroxide (BPO). Mix them thoroughly and then add them dropwise to the epoxy ester. The reaction temperature is 110℃, and the reaction time is 4h. After the reaction is complete, heat the flask to 120℃ and maintain the temperature for 4h. Determine the molecular weight of the obtained modified epoxy resin and record it in Table 1 below.

[0219] After the heat preservation is completed, the temperature is lowered to 40℃, water is added for dispersion, and a milky white waterborne epoxy resin emulsion that cures at room temperature is obtained with a solid content of 42% and a viscosity of 35s at Forte 4 cup.

[0220] Example 3

[0221] Add 240g of carboxyl-terminated polyethylene glycol 2000 (prepared as described above) to a 1000ml four-necked round-bottom flask. Raise the temperature to 110℃, then add 200g of bisphenol A epoxy resin 901 and 100g of bisphenol A epoxy resin E-51. Raise the temperature to 130℃ and react for 1 hour. Begin measuring the acid value every hour until the acid value is <10mg KOH / g, indicating the reaction has reached its endpoint.

[0222] Then, add 328g of linolenic acid to the four-necked flask and heat to 150℃. After dissolving and stirring until it becomes clear, raise the temperature to 200℃ and add 4g of stannous octoate. Take a sample every hour to measure the acid value until the acid value is <5mg KOH / g, indicating that the esterification reaction is complete. Cool down and add a mixture of n-butanol and propylene glycol methyl ether, with a n-butanol:propylene glycol methyl ether (v / v) ratio of 1:1, to control the solid content of the epoxy ester to 60%.

[0223] Take 250g of the above epoxy ester and place it in a 1000mL three-necked flask. Heat the flask to 115℃. Weigh out 20g of styrene, 18g of methyl methacrylate, 10g of butyl acrylate, 10g of butyl methacrylate, and 5g of benzoyl peroxide (BPO). Mix them thoroughly and then add them dropwise to the epoxy ester. The reaction temperature is 115℃, and the reaction time is 4h. After the reaction is complete, heat the flask to 125℃ and maintain the temperature for 4h. Determine the molecular weight of the obtained modified epoxy resin and record it in Table 1 below.

[0224] After the heat preservation is completed, the temperature is lowered to 40℃, water is added for dispersion, and a milky white waterborne epoxy resin emulsion that cures at room temperature is obtained with a solid content of 43% and a Forte 4 cup viscosity of 51s.

[0225] Example 4

[0226] Add 220g of carboxyl-terminated polyethylene glycol 4000 (prepared as described above) to a 1000ml four-necked round-bottom flask, raise the temperature to 110℃, then add 200g of bisphenol A type epoxy resin 901 and raise the temperature to 140℃. After reacting for 1 hour, start measuring the acid value. Take a sample every hour to measure the acid value until the acid value is <10mg KOH / g, at which point the reaction has reached its endpoint.

[0227] Then, add 168g of linolenic acid to the four-necked flask and heat to 150℃. After dissolving and stirring until homogeneous and transparent, raise the temperature to 200℃ and add 2g of monobutyltin oxide. Take a sample every hour to measure the acid value until the acid value is <5mg KOH / g, indicating that the esterification reaction is complete. Cool down and add a mixture of n-butanol and propylene glycol methyl ether, with a n-butanol:propylene glycol methyl ether (v / v) ratio of 1:1, to control the solid content of the epoxy ester to 60%.

[0228] 250g of the above epoxy ester was added to a 1000mL three-necked flask and heated to 120℃. 30g of styrene, 25g of ethyl acrylate, 10g of butyl acrylate, and 3g of benzoyl peroxide (BPO) were weighed and mixed thoroughly. This mixture was then added dropwise to the epoxy ester. The reaction temperature was 120℃, and the reaction time was 4 hours. After the reaction was complete, the temperature was raised to 130℃ and maintained for 5 hours. The molecular weight of the resulting modified epoxy resin was determined and recorded in Table 1 below.

[0229] After the heat preservation is completed, the temperature is lowered to 40℃, water is added for dispersion, and a milky white waterborne epoxy resin emulsion that cures at room temperature is obtained with a solid content of 39% and a Ford cup viscosity of 48s.

[0230] Comparative Example 1

[0231] Add 320g of linoleic acid to a 1000mL four-necked round-bottom flask and heat to 150℃; add 300g of bisphenol A type epoxy resin 901, heat to 200℃, stir until dissolved and transparent, then add 3g of stannous octoate. Take a sample every hour to measure the acid value until the acid value is <10mg KOH / g, indicating that the esterification reaction is complete. Cool down and add a mixture of n-butanol and ethylene glycol monobutyl ether, with n-butanol:ethylene glycol monobutyl ether (v / v) = 2:3, to control the solid content of the epoxy ester to 60%.

[0232] Take 150g of the above epoxy ester and place it in a 1000mL three-necked flask. Heat the flask to 110℃. Weigh out 25g of styrene, 15g of methyl methacrylate, 20g of butyl acrylate, 12.5g of acrylic acid, and 5g of benzoyl peroxide (BPO). Mix them thoroughly and then add them dropwise to the epoxy ester. The reaction temperature is 110℃, and the reaction time is 4h. After the reaction is complete, heat the flask to 120℃ and maintain the temperature for 4h. Determine the molecular weight of the obtained modified epoxy resin and record it in Table 1 below.

[0233] After the heat preservation is completed, the temperature is lowered to 50°C, and 15g of triethylamine is added for neutralization reaction for 1.5h, with a degree of neutralization of 85%.

[0234] After neutralization, the temperature is lowered to 40°C, water is added for dispersion, and a single-component waterborne epoxy resin emulsion that cures at room temperature is obtained with a solid content of 35% and a Forte 4 cup viscosity of 35s.

[0235] Comparative Example 2

[0236] Polyethylene glycol 2000 was dried in an oven at 85°C for 12 hours. 200g of the dried polyethylene glycol 2000 was transferred to a four-necked round-bottom flask and heated to 120°C, with nitrogen flow controlled by a bubbler. After a short while, 200g of bisphenol A epoxy resin 901 was added, along with Lewis acid as a catalyst. The mixture was mechanically stirred at 70 rpm for 4 hours. 168g of linoleic acid was added to a 1000mL four-necked round-bottom flask and heated to 150°C. After dissolving and stirring until homogeneous and transparent, the temperature was raised to 200°C, and 2g of monobutyltin oxide was added. The acid value was measured every hour until it was <10mg KOH / g, indicating the esterification reaction was complete. The mixture was then cooled and a mixture of n-butanol and ethylene glycol monobutyl ether was added, with a n-butanol:ethylene glycol monobutyl ether (v / v) ratio of 2:3, to control the solid content of the epoxy ester at 60%.

[0237] 190g of the above epoxy ester was placed in a 1000mL three-necked flask and heated to 110℃. 25g of styrene, 15g of methyl methacrylate, 20g of butyl acrylate, and 5g of benzoyl peroxide (BPO) were weighed and mixed thoroughly. This mixture was then added dropwise to the epoxy ester. The reaction temperature was 110℃, and the reaction time was 4 hours. After the reaction was complete, the temperature was raised to 120℃ and maintained for 4 hours. The molecular weight of the resulting modified epoxy resin was determined and recorded in Table 1 below.

[0238] After the heat preservation is completed, the temperature is lowered to 40℃, water is added for dispersion, and a single-component waterborne epoxy resin emulsion that cures at room temperature is obtained with a solid content of 36% and a Ford cup viscosity of 38s.

[0239] Comparative Example 3

[0240] Polyethylene glycol 2000 was dried in an oven at 85°C for 12 hours. 200g of the dried polyethylene glycol 2000 was transferred to a four-necked round-bottom flask, heated to 120°C, and the nitrogen flow rate was controlled by a bubbler. After a short while, 34g of methylhexahydrophthalic anhydride was added, and the mixture was mechanically stirred at 70 rpm for a certain period, maintaining a continuous nitrogen flow until the acid value was less than 100 mg KOH / g, reaching the reaction endpoint.

[0241] Add 54g of methylhexahydrophthalic anhydride-modified polyethylene glycol to a 1000ml four-necked round-bottom flask, raise the temperature to 110℃, then add 200g of bisphenol A type epoxy resin 901, raise the temperature to 130℃, and after reacting for 1 hour, start measuring the acid value, taking samples every hour to measure the acid value until the acid value <10mg KOH / g, indicating that the reaction has reached its endpoint. Then add 168g of linoleic acid to the four-necked flask and heat to 150℃. After dissolving and stirring until it is uniform and transparent, raise the temperature to 200℃ and add 4g of stannous octoate. Take samples every hour to measure the acid value until the acid value <5mg KOH / g, indicating that the esterification reaction is complete. Cool down and add a mixture of n-butanol and propylene glycol methyl ether, with n-butanol:propylene glycol methyl ether (v / v) = 1:1, to control the solid content of the epoxy ester to 60%.

[0242] Take 250g of the above epoxy ester and place it in a 1000mL three-necked flask. Heat the flask to 115℃. Weigh out 20g of styrene, 18g of methyl methacrylate, 10g of butyl acrylate, 10g of butyl methacrylate, and 5g of benzoyl peroxide (BPO). Mix them thoroughly and then add them dropwise to the epoxy ester. The reaction temperature is 115℃, and the reaction time is 4h. After the reaction is complete, heat the flask to 125℃ and maintain the temperature for 4h. Determine the molecular weight of the obtained modified epoxy resin and record it in Table 1 below.

[0243] After the heat preservation is completed, the temperature is lowered to 40℃, water is added for dispersion, and a milky white waterborne epoxy resin emulsion that cures at room temperature is obtained with a solid content of 38% and a Ford cup viscosity of 51s.

[0244] 5. Preparation and performance testing of coating samples

[0245] The prepared waterborne epoxy resin emulsion was mixed with 1% metal ion drier based on the resin solids content, followed by 2‰–8‰ defoamer and 5‰–1% wetting agent based on the resin solids content to obtain a one-component waterborne epoxy varnish. A 200μm layer of the varnish was then applied using a wire brush to a treated cold-rolled steel sheet and tinplate (treated by degreasing with acetone, sanding with 320-grit sandpaper, and wiping clean with ethanol). The sheets were then allowed to air dry naturally at 25°C and 55% relative humidity for 7 days, resulting in a dry film thickness of approximately 35μm. Performance tests were performed on the prepared varnish films. The tinplate samples were used to test flexibility, while the cold-rolled steel samples were used to test adhesion, water resistance, and salt spray resistance. The test results are shown in Table 1 below.

[0246] Table 1

[0247]

[0248]

[0249] *The molar ratio of PEG to epoxy refers to the ratio of the molar amount of polyethylene glycol with bilateral carboxyl-terminated ends to the molar amount of epoxy resin in the ring-opening reaction.

[0250] **Molecular weight refers to the weight-average molecular weight (Mw) of the self-emulsifying modified epoxy resin of the present invention prepared in the examples.

[0251] As shown in Table 1, the modified epoxy resin of the present invention has a high molecular weight. Furthermore, the coating film prepared from the single-component aqueous epoxy resin emulsion of the present invention exhibits better water whitening resistance, impact strength, adhesion, flexibility, and salt spray resistance, as well as a faster surface drying time, compared to anionic epoxy ester (Comparative Example 1) and epoxy resin modified only with polyethylene glycol (Comparative Example 2). In addition, due to the presence of segments derived from polyfunctional anhydrides carboxylated polyethylene glycol, compared to segments derived from other anhydrides (methylhexahydrophthalic anhydride, Comparative Example 3) carboxylated polyethylene glycol segments, the epoxy resin of the present invention yields a high-solids-content, low-viscosity aqueous epoxy resin, and after film formation, the increased crosslinking density results in better water and salt spray resistance.

[0252] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0253] It should be understood that the present invention is not limited to the contents described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A self-emulsifying modified epoxy resin, comprising: Epoxy resin The main chain of the segment and the segment derived from bilaterally carboxyl-terminated polyethylene glycol, the side chain derived from unsaturated fatty acids and the side chain derived from olefin-containing copolymerizable monomers, wherein the olefin-containing copolymerizable monomers include one or more (meth)acrylate copolymerizable monomers. The unsaturated fatty acids mentioned therein are selected from one or more of the following: oleic acid, linoleic acid, linolenic acid, ricinoleic acid, tung oil acid, soybean oil acid, myristoleic acid, octadecanoic acid, arachidonic acid, eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid. The segments derived from the bi-carboxyl-terminated polyethylene glycol are grafted by a ring-opening reaction between the bi-carboxyl-terminated polyethylene glycol and epoxy resin, and the molar ratio of the bi-carboxyl-terminated polyethylene glycol to epoxy resin in the ring-opening reaction is 1:1~6.

2. The self-emulsifying modified epoxy resin according to claim 1, wherein the molar ratio of the bi-carboxyl-terminated polyethylene glycol to the epoxy resin in the ring-opening reaction is 1:2~6.

3. The self-emulsifying modified epoxy resin according to claim 1 has a weight-average molecular weight of 20,000 to 100,000.

4. The self-emulsifying modified epoxy resin according to claim 3 has a weight-average molecular weight of 50,000 to 90,000.

5. The self-emulsifying modified epoxy resin according to any one of claims 1 to 4, wherein the bi-carboxyl-terminated polyethylene glycol has the same or different numbers of carboxyl groups at both ends of its molecular chain, and the number of carboxyl groups is independently an integer from 1 to 3.

6. The self-emulsifying modified epoxy resin according to claim 5, wherein the number of carboxyl groups is each an integer from 2 to 3.

7. The self-emulsifying modified epoxy resin according to any one of claims 1 to 4, wherein the bi-carboxyl-terminated polyethylene glycol is obtained by esterification of polyethylene glycol with polyfunctional carboxylic acids and / or polyfunctional anhydrides.

8. The self-emulsifying modified epoxy resin according to claim 7, wherein the molar ratio of the polyfunctional carboxylic acid and / or polyfunctional anhydride based on the carboxyl group to the molar ratio of polyethylene glycol based on the carboxyl-reactive end groups is 2-4:

1.

9. The self-emulsifying modified epoxy resin according to claim 8, wherein the molar ratio of the polyfunctional carboxylic acid and / or polyfunctional anhydride based on the carboxyl group to the molar ratio of the polyethylene glycol based on the end groups reactive to the carboxyl group is 3-4:

1.

10. The self-emulsifying modified epoxy resin according to claim 9, wherein the molar ratio of the polyfunctional carboxylic acid and / or polyfunctional anhydride based on the carboxyl group to the molar ratio of the polyethylene glycol based on the carboxyl-reactive end groups is 3:

1.

11. The self-emulsifying modified epoxy resin according to claim 7, wherein the multifunctional anhydride comprises trihydric anhydride, tetrahydric anhydride, or a mixture thereof.

12. The self-emulsifying modified epoxy resin according to claim 11, wherein the multifunctional anhydride comprises triacid anhydride.

13. The self-emulsifying modified epoxy resin according to claim 12, wherein the triacid anhydride is trimellitic anhydride.

14. The self-emulsifying modified epoxy resin according to claim 11, wherein the tetrahydric anhydride is pyromellitic dianhydride.

15. The self-emulsifying modified epoxy resin according to any one of claims 1 to 4, wherein the polyethylene glycol has a weight-average molecular weight of 200 to 8000.

16. The self-emulsifying modified epoxy resin according to claim 15, wherein the polyethylene glycol has a weight-average molecular weight of 2000-6000.

17. The self-emulsifying modified epoxy resin according to any one of claims 1 to 4, wherein the epoxy resin possesses one or more of the following characteristics: (1) The number-average molecular weight Mn is 400~3000; (2) The epoxy value is 0.04~0.54 eq / 100g; (3) The epoxy resin is one or more bisphenol type epoxy resins.

18. The self-emulsifying modified epoxy resin according to claim 17, wherein the number average molecular weight Mn is 500~1500.

19. The self-emulsifying modified epoxy resin according to claim 17, wherein the epoxy value is 0.1~0.3 eq / 100g.

20. The self-emulsifying modified epoxy resin according to claim 17, wherein the epoxy resin is a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a mixture thereof.

21. The self-emulsifying modified epoxy resin according to any one of claims 1 to 4, wherein the (meth)acrylate comonomer is one or more (meth)acrylates of branched or straight-chain alcohols having 1 to 10 carbon atoms.

22. The self-emulsifying modified epoxy resin according to claim 21, wherein the olefin-containing copolymerizable monomer further comprises one or more vinyl polymerizable monomers selected from the following: vinyl aromatics having up to 20 carbon atoms, olefin-bonded unsaturated nitriles, halogenated or non-halogenated olefins having 2 to 6 carbon atoms, vinyl ethers of alcohols having 1 to 10 carbon atoms, and (meth)acrylamide.

23. The self-emulsifying modified epoxy resin according to claim 22, wherein the vinyl polymerizable monomer is selected from styrene, vinyltoluene, α-methylstyrene and p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, vinyl methyl ether and vinyl isobutyl ether, and combinations thereof.

24. The self-emulsifying modified epoxy resin according to claim 23, wherein the vinyl polymerizable monomer is styrene, vinyltoluene, or a combination thereof.

25. The self-emulsifying modified epoxy resin according to any one of claims 1 to 4, which is obtained by the following steps: (1) A ring-opening reaction is carried out between a double-carboxyl-terminated polyethylene glycol and an epoxy resin to obtain an epoxy resin comprising segments derived from the double-carboxyl-terminated polyethylene glycol; in the ring-opening reaction, the molar ratio of the double-carboxyl-terminated polyethylene glycol to the epoxy resin is 1:1~6. (2) The epoxy resin comprising segments derived from bi-sided carboxyl-terminated polyethylene glycol is subjected to an esterification reaction with unsaturated fatty acids to obtain an epoxy ester. (3) The epoxy ester is subjected to free radical polymerization with an olefin-containing copolymerizable monomer to obtain the self-emulsifying modified epoxy resin; wherein the olefin-containing copolymerizable monomer includes one or more (meth)acrylate copolymerizable monomers.

26. A method for preparing a self-emulsifying modified epoxy resin, comprising the following steps: (1) A ring-opening reaction is carried out between polyethylene glycol with bilateral carboxyl groups and epoxy resin to obtain an epoxy resin including segments derived from polyethylene glycol with bilateral carboxyl groups. In the ring-opening reaction, the molar ratio of the bi-carboxyl-terminated polyethylene glycol to the epoxy resin is 1:1~6. (2) The epoxy resin comprising segments derived from bilaterally carboxyl-terminated polyethylene glycol is subjected to an esterification reaction with unsaturated fatty acids to obtain an epoxy ester, wherein the unsaturated fatty acids are selected from one or more of the following: oleic acid, linoleic acid, linolenic acid, ricinoleic acid, tung oil acid, soybean oil acid, myristoleic acid, octadecanoic acid, arachidonic acid, eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid; (3) The epoxy ester is subjected to free radical polymerization with a copolymerizable monomer containing an olefin bond to obtain the self-emulsifying modified epoxy resin; The self-emulsifying modified epoxy resin comprises: an epoxy resin chain segment and a main chain of a polyethylene glycol chain segment derived from bilaterally carboxyl-terminated segments, a side chain derived from unsaturated fatty acids, and a side chain derived from an olefin-containing copolymerizable monomer; and the olefin-containing copolymerizable monomer comprises one or more (meth)acrylate copolymerizable monomers.

27. The method according to claim 26, wherein, The bilaterally carboxyl-terminated polyethylene glycol is obtained by reacting polyethylene glycol with polyfunctional carboxylic acids and / or polyfunctional anhydrides; wherein the molar ratio of the polyfunctional carboxylic acids and / or polyfunctional anhydrides based on carboxyl groups to the molar ratio of polyethylene glycol based on carboxyl-reactive end groups is 2-4:

1.

28. The method according to claim 27, wherein the molar ratio of the polyfunctional carboxylic acid and / or polyfunctional anhydride based on the carboxyl group to the molar ratio of polyethylene glycol based on the carboxyl-reactive end group is 3-4:

1.

29. The method according to any one of claims 26 to 28, wherein after the esterification reaction in step (2) is completed, an organic solvent is added to make the solid content of the epoxy ester 50% to 80%.

30. The method according to claim 29, wherein the organic solvent is selected from one or more of the following: ketones, aromatic hydrocarbons, aliphatic hydrocarbons, ethers, esters, alcohols and petroleum-based solvents.

31. The method of claim 30, wherein the organic solvent is a mixture of alcohol and ether.

32. The method of claim 31, wherein the organic solvent is a mixture of an alcohol and an ether of a diol.

33. The method of claim 31, wherein the volume ratio of the alcohol to the ether is 2:3 to 3:

2.

34. The method according to claim 30, wherein the ketone is selected from one or more of methyl ethyl ketone, cyclohexanone, isophorone, and diacetone alcohol.

35. The method according to claim 30, wherein the aromatic hydrocarbon is selected from one or more of toluene, xylene, trimethylbenzene, and tetramethylbenzene.

36. The method of claim 30, wherein the ether is selected from one or more of propylene glycol methyl ether, ethylene glycol monobutyl ether, and triethylene glycol monoethyl ether.

37. The method according to claim 30, wherein the ester is selected from one or more of ethyl acetate, butyl acetate, dimethyl adipate, dimethyl succinate, dimethyl glutarate, dimethyl ethylene glycol, diethyl ethylene glycol, dimethyl propylene glycol, diethyl propylene glycol, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate.

38. The method of claim 30, wherein the alcohol is selected from one or more of ethanol, propanol, n-butanol, isopropanol, ethylene glycol, and propylene glycol.

39. The method of claim 30, wherein the aliphatic hydrocarbon is selected from octane or cyclohexane.

40. The method according to claim 30, wherein the petroleum-based solvent is selected from one or more of petroleum ether and naphtha.

41. The method of claim 40, wherein the naphtha is hydrogenated naphtha.

42. The method of claim 40, wherein the naphtha is solvent naphtha.

43. The method of claim 32, wherein the organic solvent is a mixture of n-butanol and propylene glycol methyl ether or ethylene glycol monobutyl ether.

44. A self-emulsifying one-component aqueous epoxy resin emulsion, comprising: water, And the self-emulsifying modified epoxy resin according to any one of claims 1 to 25 or the self-emulsifying modified epoxy resin prepared by the method according to any one of claims 26 to 43.

45. The self-emulsifying one-component aqueous epoxy resin emulsion according to claim 44, comprising one or more of the following characteristics: (1) Its solid content is 20-55%, based on the total weight of the aqueous emulsion; (2) Its pH is 7~9; (3) Its viscosity is 20~120 seconds, determined by the Coulomb viscometer method according to GB / T 1725-93.

46. ​​The self-emulsifying single-component aqueous epoxy resin emulsion according to claim 45, wherein the solid content is 30-45% based on the total weight of the aqueous emulsion.

47. The self-emulsifying single-component aqueous epoxy resin emulsion according to claim 45 has a viscosity of 30-80 seconds, determined by the Forte 4 viscometer method according to GB / T 1725-93.

48. A method for preparing a self-emulsifying one-component aqueous epoxy resin emulsion, comprising: Water is added to the self-emulsifying modified epoxy resin according to any one of claims 1 to 25 or the self-emulsifying modified epoxy resin prepared by the method according to any one of claims 26 to 43, and the mixture is stirred.

49. Use of the self-emulsifying one-component aqueous epoxy resin emulsion according to any one of claims 44 to 47 as a coating.

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