Oxazolinyl-containing copolymer, preparation method thereof and application of oxazolinyl-containing copolymer as water-based oxazoline cross-linking agent

Abstract

The invention relates to an oxazolinyl-containing copolymer, a preparation method of the oxazolinyl-containing copolymer and application of the oxazolinyl-containing copolymer as a water-based oxazoline cross-linking agent, and belongs to the technical field of water-based cross-linking agents. The oxazoline group-containing copolymer provided by the invention comprises: a) at least one monomer (a) selected from C1-20 alkyl (meth) acrylate and C8-20 vinyl aromatic compounds; b) at least one ethylenically unsaturated monomer (b), said ethylenically unsaturated monomer (b) comprising an oxazoline group; c) at least one ethylenically unsaturated monomer (c), the ethylenically unsaturated monomer (c) comprises a polyether group, and the structure of the ethylenically unsaturated monomer (c) is at least one of the formula (1). The oxazoline group-containing copolymer has good water dilutability, and can improve the adhesive force and hot water resistance of water-based paint, ink and adhesives as a water-based oxazoline cross-linking agent.

Description

Technical Field

[0001] The present invention relates to the technical field of water-based crosslinking agents, in particular to a copolymer containing oxazoline groups, a preparation method thereof and an application thereof as a water-based oxazoline crosslinking agent. Background Art

[0002] Water-based coatings, inks, and adhesive compositions have significant advantages in environmental performance, can significantly reduce the emission of volatile organic compounds (VOCs), and effectively reduce potential hazards to human health. However, compared with traditional solvent-based coatings, inks, and adhesive compositions, water-based systems have obvious shortcomings in many key performance aspects, such as adhesion to the substrate, wear resistance, solvent resistance, and hydrolysis resistance, which are not satisfactory. Water-based oxazoline crosslinkers provide an effective way to solve these problems. They can undergo cross-linking reactions with the carboxyl groups contained in water-based resins under high temperature conditions of 80-120°C, thereby significantly improving the overall performance of the coating. It is worth mentioning that water-based oxazoline crosslinkers have multiple advantages: not only are they non-toxic and environmentally friendly, which is in line with the current green development concept, but they also have a long service life and can be stored in a single-component form, greatly simplifying the storage and use process. In view of these outstanding advantages, water-based oxazoline crosslinkers have become an extremely ideal high-performance water-based crosslinker and have been widely used in related fields.

[0003] At present, by the unsaturated monomers containing oxazoline radical and the unsaturated monomer copolymerization containing hydrophilic group is the main method for preparing water-based oxazoline group-containing polymer.Because oxazoline group can react with carboxyl, so seldom use carboxyl-containing unsaturated monomers to carry out copolymerization as hydrophilic monomer.Therefore, introducing suitable non-carboxyl hydrophilic group is the key for preparing water-based oxazoline group-containing polymer.Disclose respectively the synthetic method of water-based oxazoline cross-linking agent in US5300602A and US6548182, in some embodiments therein, by methoxy polyethylene glycol methacrylate, the unsaturated monomers containing oxazoline radical, other (methyl) acrylate monomers, in aqueous phase, carry out free radical polymerization and obtain.CN106604943B discloses a kind of preparation method of the multipolymer that comprises oxazoline monomer, by the unsaturated hydrophilic monomers containing sulfonic acid group (as 2-acrylamido-2-propanesulfonic acid sodium salt), the unsaturated monomers containing oxazoline radical, other (methyl) acrylate monomers, in aqueous phase, carry out free radical polymerization and obtain. But above method all has some defectives, for example, the methoxy polyethylene glycol methacrylate adopted in US5300602A and US6548182 is comparatively expensive, and the unsaturated hydrophilic monomer containing too much sulfonic acid group in CN106604943B can cause the variation of water resistance, and performance still has the room of improving.And it is still very rare that water-based contains the method that oxazoline group polymer is introduced hydrophilic group at present, and finding new method to introduce hydrophilic group is of great significance for developing this class high performance polymer of water-based oxazoline crosslinking agent. Summary of the Invention

[0004] Based on this, the object of the present invention is to overcome the defects or shortcomings of the prior art and provide a copolymer containing oxazoline groups and a preparation method thereof and an application as a water-based oxazoline crosslinking agent. The copolymer containing oxazoline groups is used as a water-based oxazoline crosslinking agent (an effective ingredient) in water-based coatings, inks or adhesive compositions, and has excellent water dilution, adhesion, and hot water resistance to improve the performance of water-based coatings, inks or adhesive compositions.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides an oxazoline-containing copolymer, comprising:

[0007] a) at least one monomer (a) selected from C1-20 alkyl (meth)acrylates and C8-20 vinyl aromatic compounds;

[0008] b) at least one ethylenically unsaturated monomer (b), said ethylenically unsaturated monomer (b) comprising an oxazoline group;

[0009] c) at least one ethylenically unsaturated monomer (c), said ethylenically unsaturated monomer (c) comprising a polyether group, and said ethylenically unsaturated monomer (c) having a structure of at least one of formula (1):

[0010]

[0011] In formula (1), R1 and R2 are each independently hydrogen or methyl; R3 is a hydrocarbon group having 1 to 8 carbon atoms; Z is a divalent aliphatic hydrocarbon group or aromatic hydrocarbon group having 1 to 8 carbon atoms; x is 0 or 1; y is 6 to 68;

[0012] In the oxazoline-containing copolymer, the proportion of the monomer (a) in the oxazoline-containing copolymer is 0-40wt%, the proportion of the ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 38-70wt%, and the proportion of the ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 15-50wt%.

[0013] The oxazoline-containing copolymer of the present invention, by introducing an ethylenically unsaturated monomer (c) containing a polyether group and having a specific structure of formula (1), can make the water-dilutable copolymer of the oxazoline-containing copolymer good, and can be used as a water-based oxazoline crosslinking agent (an effective ingredient) in water-based coatings, inks or adhesive compositions, etc., to improve the adhesion and hot water resistance of the water-based coatings, inks or adhesive compositions, etc.

[0014] In the structure of the ethylenically unsaturated monomer (c), that is, in formula (1), y is limited to 6-68, which is beneficial to ensuring the hydrophilicity of the oxazoline-containing copolymer while ensuring the polymerization reaction activity of the ethylenically unsaturated monomer (c); if the y value is too low, the polymerization degree of the polyether group is too low, resulting in too low hydrophilicity of the oxazoline-containing copolymer, thereby affecting the water dilution of the water-based oxazoline cross-linker; if the y value is too large, the polymerization reaction activity of the ethylenically unsaturated monomer (c) is low, and the reaction time in polymerizing with other monomers to form the oxazoline-containing copolymer will be longer.

[0015] The present inventor has found through repeated studies, and the ratio that controlling described ethylenically unsaturated monomer (c) to account for the described multipolymer containing oxazoline-based is 15-50wt%, is conducive to ensuring the hot water resistance when the described multipolymer containing oxazoline-based is used for water-based coatings, ink or adhesive composition as aqueous oxazoline crosslinking agent (active ingredient) when the wetting property of the described multipolymer containing oxazoline-based is ensured.If the ratio that described ethylenically unsaturated monomer (c) accounts for the described multipolymer containing oxazoline-based is too low, the water dilutability that can cause aqueous oxazoline crosslinking agent is not good, this may be due to the contained polyether groups of described ethylenically unsaturated monomer (c) having good wetting property, the too low wetting property that content can cause the described multipolymer containing oxazoline-based is not good, and then causes water dilutability not good; If the ratio that described ethylenically unsaturated monomer (c) accounts for the described multipolymer containing oxazoline-based is too high, the described wetting property of the multipolymer containing oxazoline-based is too high, also can affect the coating of preparation, ink, the hot water resistance of adhesive.

[0016] In addition, the present invention is by in the described multipolymer that contains oxazoline-based, the ratio that controlling described ethylenically unsaturated monomer (b) accounts for the described multipolymer that contains oxazoline-based is 38-70wt%, guarantee to contain a certain amount of oxazoline groups in the described multipolymer that contains oxazoline-based, so that the described multipolymer that contains oxazoline-based is used for water-based coatings, printing ink or adhesive compositions etc. as water-based oxazoline cross-linking agent (active ingredient), helps cross-linking reaction.And in the described multipolymer that contains oxazoline-based, the ratio that described monomer (a) accounts for the described multipolymer that contains oxazoline-based is 0-40wt%, shows that the present invention can also introduce and also can not introduce described monomer (a) in the described multipolymer that contains oxazoline-based, and those skilled in the art can select according to actual needs content.

[0017] As a preferred embodiment of the present invention, the monomer (a) is at least one of methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, tridecyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, n-dodecyl (meth)acrylate, benzyl (meth)acrylate, styrene, α-methylstyrene, and vinyltoluene. Preferably, the monomer (a) is at least one of methyl methacrylate and ethyl acrylate.

[0018] As a preferred embodiment of the present invention, the ethylenically unsaturated monomer (b) is 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-vinyl-4-ethyl-2-oxazoline, 2-vinyl-4,4-dimethyl-2-oxazoline, 2-vinyl-5,5-dimethyl-2-oxazoline, 2-vinyl-4,4,5,5-tetramethyl-2-oxazoline, 2 At least one of isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-4-ethyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2-isopropenyl-4,4-dimethyl-2-oxazoline, 2-isopropenyl-5,5-dimethyl-2-oxazoline, and 2-isopropenyl-4,4,5,5-tetramethyl-2-oxazoline. Preferably, at least one of 2-isopropyl-2-oxazoline and 2-vinyl-2-oxazoline.

[0019] As a preferred embodiment of the present invention, the ethylenically unsaturated monomer (c) is obtained by reacting a carboxyl-containing polyether G with the ethylenically unsaturated monomer (b); the structure of the carboxyl-containing polyether G is at least one of formula (2):

[0020]

[0021] In formula (2), R2 is hydrogen or methyl; R3 is a hydrocarbon group having 1 to 8 carbon atoms; Z is a divalent aliphatic hydrocarbon group or aromatic hydrocarbon group having 1 to 8 carbon atoms; x is 0 or 1; and y is an integer of 6-68.

[0022] In the present invention, the ethylenically unsaturated monomer (c) can be obtained by a ring-opening reaction between the carboxyl group on the carboxyl-containing polyether G of formula (2) and the oxazoline group of the ethylenically unsaturated monomer (b).

[0023] The present invention also provides a method for preparing any of the above-mentioned oxazoline-containing copolymers, comprising the following steps: polymerizing the monomer (a), the ethylenically unsaturated monomer (b) and the ethylenically unsaturated monomer (c) to obtain.

[0024] In the preparation method, the monomer (a), the ethylenically unsaturated monomer (b), and the unsaturated double bonds (olefinic bonds) of the ethylenically unsaturated monomer (c) are polymerized to obtain the oxazoline group-containing copolymer.

[0025] The present invention also provides another method for preparing any of the above-mentioned oxazoline-containing copolymers, comprising the following steps: reacting the monomer (a), the ethylenically unsaturated monomer (b) and the carboxyl-containing polyether G to prepare the copolymer, wherein the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G, and during the reaction, a polymerization reaction of unsaturated double bonds and a ring-opening reaction between the carboxyl-containing polyether G and the ethylenically unsaturated monomer (b) occur; the structure of the carboxyl-containing polyether G is at least one of formula (2):

[0026]

[0027] In formula (2), R2 is hydrogen or methyl; R3 is a hydrocarbon group having 1 to 8 carbon atoms; Z is a divalent aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 8 carbon atoms; x is 0 or 1; and y is 6-68.

[0028] In the preparation method, the ethylenically unsaturated monomer (c) is indirectly obtained by adding the carboxyl-containing polyether G and carrying out a ring-opening reaction with a portion of the ethylenically unsaturated monomer (b). At the same time, since the ethylenically unsaturated monomer (b) is excessive relative to the carboxyl-containing polyether G, the ethylenically unsaturated monomer (b) still remains after the reaction of the carboxyl-containing polyether G is complete, thereby making the prepared oxazoline-containing copolymer equivalent to that obtained by polymerization of the monomer (a), the ethylenically unsaturated monomer (b) and the ethylenically unsaturated monomer (c).

[0029] The present invention also provides a kind of above-mentioned arbitrary described multipolymer that contains oxazoline-based purposes in aqueous oxazoline crosslinking agent.Particularly, the present invention also provides a kind of aqueous oxazoline crosslinking agent, comprise above-mentioned arbitrary described multipolymer that contains oxazoline-based and water, wherein water accounts for the 30-90wt% of described multipolymer that contains oxazoline-based and water total amount.By adopting above-mentioned arbitrary described multipolymer that contains oxazoline-based effective ingredient as described aqueous oxazoline crosslinking agent, described aqueous oxazoline crosslinking agent can be made to be applied in water-based coating, ink or adhesive composition, has extraordinary water dilutability, sticking power, hot water resistance.

[0030] In the water-based oxazoline crosslinking agent, water accounts for 30-90wt% of the total amount of the oxazoline-containing copolymer and water. If the content of water in the total amount of the oxazoline-containing copolymer and water is too low, the viscosity of the water-based oxazoline crosslinking agent is easily too high. If the content of water in the total amount of the oxazoline-containing copolymer and water is too high, the content of the active ingredient of the water-based oxazoline crosslinking agent is too low, and more water-based oxazoline crosslinking agent needs to be added during use to fully exert its crosslinking effect, which increases the inconvenience during use.

[0031] Further, described aqueous oxazoline crosslinking agent also comprises organic solvent, and described organic solvent accounts for the 5-50wt% of described multipolymer, water and the organic solvent total amount that contain oxazoline-based.Described organic solvent can be at least one in alcohols, alcohol ethers, ketones, esters, aromatic hydrocarbons etc., is preferably at least one in the good water-soluble organic solvents such as propylene glycol methyl ether, isopropyl alcohol, can not affect the water dilutability of described aqueous oxazoline crosslinking agent.For the consideration of environmental protection and low VOC discharge, be preferably the 5-35wt% that described organic solvent accounts for the described multipolymer, water and the organic solvent total amount that contain oxazoline-based.

[0032] The preparation process of the oxazoline-containing copolymer is more advantageously carried out in an aqueous system or a system in which water and an organic solvent are mixed. Therefore, while the present invention preferably prepares the oxazoline-containing copolymer in an aqueous system or a system in which water and an organic solvent are mixed, the water-based oxazoline crosslinker of the present invention can also be directly obtained by regulating the proportion of water or organic solvent. Specifically:

[0033] The present invention also provides a method for preparing any of the above-mentioned water-based oxazoline crosslinking agents, comprising the following steps: adding water or water and an organic solvent into a reaction container, adding an initiator, heating to 50-90° C., adding (preferably dropwise) a mixture of the monomer (a), the ethylenically unsaturated monomer (b) and the ethylenically unsaturated monomer (c) into the reaction container for reaction, and finally obtaining the water-based oxazoline crosslinking agent.

[0034] During the reaction process of the preparation method, a polymerization reaction of unsaturated double bonds (olefinic bonds) occurs between the monomer (a), the ethylenically unsaturated monomer (b), and the ethylenically unsaturated monomer (c) to obtain the oxazoline-containing copolymer; in addition, the reaction system also contains water or water and an organic solvent, so that the final product is the water-based oxazoline crosslinker of the present invention.

[0035] The present invention also provides another method for preparing any of the above-mentioned water-based oxazoline crosslinking agents, comprising the following steps: adding the carboxyl-containing polyether (G) into a container, adding water or water and an organic solvent, and adding an initiator, heating to 50-90° C., adding (preferably dropwise) a mixture of monomer (a) and ethylenically unsaturated monomer (b) into a reaction container for reaction, wherein the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G, and finally obtaining the water-based oxazoline crosslinking agent.

[0036] The carboxyl-containing polyether G structure is at least one of formula (2):

[0037]

[0038] Wherein, R2 is hydrogen or methyl; R3 is a hydrocarbon group having 1 to 8 carbon atoms; Z is a divalent aliphatic hydrocarbon group or aromatic hydrocarbon group having 1 to 8 carbon atoms; x is 0 or 1; and y is an integer of 6-68.

[0039] During the reaction process of the preparation method, a ring-opening reaction between the carboxyl-containing polyether G and the ethylenically unsaturated monomer (b) (forming the ethylenically unsaturated monomer (c)) and a polymerization reaction of the unsaturated double bonds between the monomers occur simultaneously among the monomer (a), the ethylenically unsaturated monomer (b), and the carboxyl-containing polyether G. Since the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G, the prepared oxazoline-containing copolymer is equivalent to that obtained by polymerization of the monomer (a), the ethylenically unsaturated monomer (b), and the ethylenically unsaturated monomer (c). In addition, the reaction system also contains water or water and an organic solvent, so that the final product is the water-based oxazoline crosslinking agent of the present invention.

[0040] The present invention also provides the use of any of the above-mentioned water-based oxazoline crosslinking agents in water-based coatings, inks, or adhesive compositions. Specifically, the present invention also provides a water-based coating, ink, or adhesive composition comprising a carboxyl-containing water-based resin and any of the above-mentioned water-based oxazoline crosslinking agents.

[0041] As a preferred solution of the present invention, the carboxyl-containing aqueous resin may be at least one of a carboxyl-containing aqueous acrylic resin, a carboxyl-containing aqueous polyurethane resin, a carboxyl-containing aqueous polyester resin, and the like.

[0042] As a preferred scheme of the present invention, in described water-based paint, ink or adhesive composition, described water-based oxazoline crosslinking agent is the 2-10wt% of described carboxyl-containing water-based resin.If the ratio that described water-based oxazoline crosslinking agent accounts for described carboxyl-containing water-based resin is too high, cost can be improved; If the ratio that described water-based oxazoline crosslinking agent accounts for described carboxyl-containing water-based resin is too low, crosslinking degree is not enough, and can affect the performances such as water resistance, chemical resistance of water-based paint, ink or adhesive composition.

[0043] Furthermore, the water-based paint, ink, or adhesive composition further comprises an auxiliary agent, wherein the proportion of the auxiliary agent in the water-based paint, ink, or adhesive composition is 2-30 wt %. By adding the auxiliary agent, the performance and decorative effect of the water-based paint, ink, or adhesive composition can be improved. Preferably, the proportion of the auxiliary agent in the water-based paint, ink, or adhesive composition is 5-25 wt %.

[0044] As a preferred embodiment, the additives include one or more of a defoamer, a leveling agent, a film-forming aid, or a thickener. The defoamer is present in an amount of 0.1-1 wt% in the water-based coating, ink, or adhesive composition; the leveling agent is present in an amount of 0.1-1 wt% in the water-based coating, ink, or adhesive composition; the film-forming aid is present in an amount of 1-10 wt% in the water-based coating, ink, or adhesive composition; and the thickener is present in an amount of 0.1-2 wt% in the water-based coating, ink, or adhesive composition. Defoaming agents are used to eliminate bubbles generated during the stirring process and the reaction process; leveling agents act on the interface between the liquid and air of water-based coatings, inks or adhesive compositions to improve the flatness of the paint film surface and prevent defects such as Bénard cells; film-forming aids are used to improve the film-forming properties of water-based coatings, inks or adhesive compositions, and to establish a volatility gradient to improve the surface effect of the coating; thickeners are used to adjust the rheological properties of water-based coatings, inks or adhesive compositions to improve the anti-sagging, anti-splashing and other properties of the coatings, inks or adhesive compositions.

[0045] As a preferred embodiment, the defoamer is at least one of a polysiloxane defoamer and a mineral oil defoamer; the leveling agent is at least one of a polysiloxane leveling agent and an acrylic leveling agent; the film-forming agent is at least one of ethylene glycol butyl ether, propylene glycol butyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, and dipropylene glycol butyl ether; and the thickener is at least one of a polyurethane thickener, an alkali-swellable acrylic thickener, and bentonite. The above-mentioned defoamers, leveling agents, film-forming agents, and thickeners do not limit the present invention; those skilled in the art may also select other types of defoamers, leveling agents, film-forming agents, and thickeners according to actual needs.

[0046] The present invention also provides a method for preparing any of the above-mentioned water-based coatings, inks or adhesive compositions, comprising the following steps: uniformly mixing the components to obtain the water-based coatings, inks or adhesive compositions.

[0047] As an application, the present invention provides a product coated with any of the above-mentioned water-based coatings, inks, or adhesive compositions, which is formed by applying the water-based coatings, inks, or adhesive compositions containing the water-based oxazoline crosslinking agent to the surface of a substrate.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The oxazoline-containing copolymer of the present invention can be used as a water-based oxazoline crosslinking agent (effective component) and applied to water-based coatings, inks, and adhesive compositions, and has very good water dilutability, adhesion, and hot water resistance. DETAILED DESCRIPTION

[0050] The present invention is further described below with reference to the examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples where specific conditions are not specified are generally performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection claimed in the present invention.

[0051] Example 1

[0052] This embodiment provides a water-based oxazoline crosslinker D1, which is prepared by the following process:

[0053] (1) Preparation of carboxyl-containing polyether G1:

[0054] The reaction flask was filled with nitrogen and 187.5 g of Clariant M750 (polyethylene glycol monomethyl ether, 750 molecular weight) was added, 39.0 g of 2,2,6,6-tetramethylpiperidinyl oxide (TEMPO, Aladdin Chemical Reagent), 500.0 g of dichloromethane was added, and the mixture was heated to reflux and passed through with dry air. 15.6 g of concentrated nitric acid was added and added over 15 min, and the mixture was then heated under reflux for 17 h. 250.0 g of isopropyl alcohol was then added and stirred for 1 h. The volatile components were removed by vacuum to obtain 180.2 g of product (i.e., carboxyl-containing polyether G1). The test acid value was 72 mg KOH / g, and the calculated carboxyl equivalent weight was about 780.

[0055] Wherein, the carboxyl-containing polyether G1 satisfies the general formula (2), and R2 is hydrogen, R3 is methyl, Z is methylene, and the average value of y is is 15.3, x is 0.

[0056] (2) Preparation of water-based oxazoline crosslinker D1

[0057] A reaction flask was purged with nitrogen, and 25.0 g of carboxyl polyether G1, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added. The flask was heated to 80°C, and 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (47.0 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate over 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D1.

[0058] Wherein, the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G1, and the detected acid value is zero, indicating that the carboxyl-containing polyether G1 has completely reacted with the oxazoline group in the ethylenically unsaturated monomer (b). During the reaction process, a ring-opening reaction (forming ethylenically unsaturated monomer (c)) between the carboxyl-containing polyether G1 and the ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds (olefinic bonds) between the monomers simultaneously occur between the monomer (a), the ethylenically unsaturated monomer (b), and the carboxyl-containing polyether G1, thereby obtaining a copolymer containing an oxazoline group.

[0059] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 28.0 wt%, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 43.4 wt%, and the proportion of ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 28.6 wt%.

[0060] The solid content of the water-based oxazoline crosslinker D1 of this embodiment is 40%, and the equivalent weight of oxazoline (based on solid content) is 271. In the water-based oxazoline crosslinker D1 of this embodiment, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0061] The aqueous oxazoline crosslinker D1 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0062] Example 2

[0063] This embodiment provides a water-based oxazoline crosslinker D2, which is prepared by the following process:

[0064] (1) Preparation of carboxyl-containing polyether G2:

[0065] The reaction flask is filled with nitrogen and 43.8g of Clariant M350 (polyethylene glycol monomethyl ether, 350 molecular weight) is added, 39.0g of 2,2,6,6-tetramethylpiperidinyl oxide (TEMPO, Aladdin Chemical Reagent), 160.0g of dichloromethane is added, and heated to reflux and passed through with dry air. 15.6g of concentrated nitric acid is added and added over 15min, and the mixture is then heated under reflux for 17h. 80.0g of isopropyl alcohol is then added and stirred for 1h. The volatile components are removed by vacuum to obtain 40.7g of product (i.e., carboxyl-containing polyether G2), and the test acid value is 148mgKOH / g, and the calculated carboxyl equivalent is about 380.

[0066] Wherein, the carboxyl-containing polyether G2 satisfies the general formula (2), and R2 is hydrogen, R3 is methyl, Z is methylene, and the average value of y is is 6.2, and x is 0.

[0067] (2) Preparation of water-based oxazoline crosslinker D2:

[0068] The reaction flask was purged with nitrogen, and 25.0 g of carboxyl polyether G2, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added and heated to 80°C. 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (47.0 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate over 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D2.

[0069] Wherein, ethylenically unsaturated monomer (b) is excessive relative to carboxyl-containing polyether G2, and the acid value detected is zero, indicating that carboxyl-containing polyether G2 has completely reacted with the oxazoline group in ethylenically unsaturated monomer (b).In the reaction process, between monomer (a), ethylenically unsaturated monomer (b), carboxyl-containing polyether G2, the ring-opening reaction (forming ethylenically unsaturated monomer (c)) of carboxyl-containing polyether G2 and ethylenically unsaturated monomer (b) and the polymerization reaction of the unsaturated double bond (olefinic bond) between each monomer occur simultaneously, thereby obtaining the copolymer containing oxazoline group.

[0070] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 28.0 wt%, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 39.7 wt%, and the proportion of ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 32.3 wt%.

[0071] The solid content of the water-based oxazoline crosslinker D2 of this embodiment is 40%, and the equivalent weight (based on solids) of oxazoline is 297. In the water-based oxazoline crosslinker D2 of this embodiment, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0072] The aqueous oxazoline crosslinker D2 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0073] Example 3

[0074] This embodiment provides a water-based oxazoline crosslinker D3, which is prepared by the following process:

[0075] (1) Preparation of carboxyl-containing polyether G3:

[0076] The reaction flask is filled with nitrogen and 375g of Clariant M3000 FL (polyethylene glycol monomethyl ether, 3000 molecular weight) is added, 39.0g of 2,2,6,6-tetramethylpiperidinyl oxide (TEMPO, Aladdin Chemical Reagent), 160.0g of dichloromethane are added, and heated to reflux and passed through with dry air. 15.6g of concentrated nitric acid is added, and the mixture is heated at reflux for 17h after 15min addition. 80.0g of isopropyl alcohol is then added and stirred for 1h. The volatile component is removed by vacuum and 356g of product (i.e., carboxyl-containing polyether G3) is obtained. The test acid value is 18.5mgKOH / g, and the calculated carboxyl equivalent is about 3030.

[0077] Among them, the carboxyl-containing polyether G3 satisfies the general formula (2), and R2 is hydrogen, R3 is methyl, Z is methylene, and the average value of y is is 66.4, and x is 0.

[0078] (2) Preparation of water-based oxazoline crosslinker D3:

[0079] The reaction flask was purged with nitrogen, and 25.0 g of carboxyl polyether G3, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added and heated to 80°C. 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (47.0 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate over 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D3.

[0080] Wherein, ethylenically unsaturated monomer (b) is excessive with respect to carboxyl-containing polyether G3, and the acid value detected is zero, indicating that carboxyl-containing polyether G3 has completely reacted with the oxazoline group in ethylenically unsaturated monomer (b).In the reaction process, between monomer (a), ethylenically unsaturated monomer (b), carboxyl-containing polyether G3, ring-opening reaction (forming ethylenically unsaturated monomer (c)) of carboxyl-containing polyether G3 and ethylenically unsaturated monomer (b) and polymerization reaction of unsaturated double bonds (olefinic bonds) between each monomer occur simultaneously, thereby obtaining the copolymer containing oxazoline group.

[0081] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 28.0 wt%, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 46.1 wt%, and the proportion of ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 25.9 wt%.

[0082] The solid content of the water-based oxazoline crosslinker D3 of this embodiment is 40%, and the equivalent weight (based on solids) of oxazoline is 256. In the water-based oxazoline crosslinker D3 of this embodiment, water accounts for 44.3wt% of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7wt% of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0083] The aqueous oxazoline crosslinker D3 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0084] Example 4

[0085] This embodiment provides a water-based oxazoline crosslinker D4, which is prepared by the following process:

[0086] (1) Preparation of carboxyl-containing polyether G4:

[0087] The reaction flask was purged with nitrogen and 312.5 g of Clariant B11 / 150 (butyl mono-terminated ethylene oxide and propylene oxide copolymer, 2500 molecular weight, ethylene oxide / propylene oxide molar ratio = 1:1) was added, 39.0 g of 2,2,6,6-tetramethylpiperidinyl oxide (TEMPO, Aladdin Chemical Reagent), and 600.0 g of dichloromethane were added and heated to reflux while passing dry air. 15.6 g of concentrated nitric acid was added over 15 minutes, and the mixture was then heated under reflux for 17 hours. 80.0 g of isopropanol was then added and stirred for 1 hour. The volatile components were removed by vacuum extraction to obtain 300.5 g of product (i.e., carboxyl-containing polyether G4). The acid value was tested to be 22.2 mgKOH / g, and the calculated carboxyl equivalent weight was approximately 2530.

[0088] Among them, the carboxyl-containing polyether G4 satisfies the general formula (2), and R2 is hydrogen and methyl (the molar ratio of hydrogen to methyl is 1:1), R3 is n-butyl, Z is methylene, and the average value of y is is 46.7, and x is 0.

[0089] (2) Preparation of water-based oxazoline crosslinker D4:

[0090] The reaction flask was purged with nitrogen, and 25.0 g of carboxyl polyether G4, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added and heated to 80°C. 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (47.0 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate within 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D4.

[0091] Wherein, ethylenically unsaturated monomer (b) is excessive with respect to carboxyl-containing polyether G4, and the acid value detected is zero, indicating that carboxyl-containing polyether G4 has completely reacted with the oxazoline group in ethylenically unsaturated monomer (b). During the reaction process, between monomer (a), ethylenically unsaturated monomer (b), and carboxyl-containing polyether G4, a ring-opening reaction (forming ethylenically unsaturated monomer (c)) of carboxyl-containing polyether G4 and ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds (olefinic bonds) between the monomers simultaneously occur, thereby obtaining a copolymer containing oxazoline groups.

[0092] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 28.0 wt%, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 45.9 wt%, and the proportion of ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 26.1 wt%.

[0093] The solid content of the water-based oxazoline crosslinker D4 of this embodiment is 40%, and the equivalent weight (based on solids) of oxazoline is 257. In the water-based oxazoline crosslinker D4 of this embodiment, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0094] The water-based oxazoline crosslinker D4 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0095] Example 5

[0096] This embodiment provides a water-based oxazoline crosslinker D5, which is prepared by the following process:

[0097] (1) Preparation of carboxyl-containing polyether G5:

[0098] The reaction flask was purged with nitrogen, and 750 g of Clariant M750 (polyethylene glycol monomethyl ether, 750 molecular weight) and 168.2 g of methylhexahydrophthalic anhydride were added. The mixture was heated to 120° C. and reacted for 4 h. Infrared spectrum detection showed that the hydroxyl groups were almost completely converted to obtain a product (i.e., carboxyl-containing polyether G5). The acid value was 61 mgKOH / g, and the calculated carboxyl equivalent weight was approximately 918.

[0099] Among them, the carboxyl-containing polyether G5 satisfies the general formula (2), and R2 is hydrogen, R3 is methyl, and the average value of y is is 15.3, x is 1, and Z is a divalent alicyclic hydrocarbon group of 7 carbon atoms represented by formula (3):

[0100]

[0101] (2) Preparation of water-based oxazoline crosslinker D5:

[0102] The reaction flask was purged with nitrogen, and 25.0 g of carboxyl polyether G5, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added and heated to 80°C. 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (47.0 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate within 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D5.

[0103] Wherein, ethylenically unsaturated monomer (b) is excessive with respect to carboxyl-containing polyether G5, and the acid value detected is zero, indicating that carboxyl-containing polyether G5 has completely reacted with the oxazoline group in ethylenically unsaturated monomer (b).In the reaction process, between monomer (a), ethylenically unsaturated monomer (b), carboxyl-containing polyether G5, ring-opening reaction (forming ethylenically unsaturated monomer (c)) of carboxyl-containing polyether G5 and ethylenically unsaturated monomer (b) and polymerization reaction of unsaturated double bonds (olefinic bonds) between each monomer occur simultaneously, thereby obtaining the copolymer containing oxazoline group.

[0104] In the oxazoline-containing copolymer, the proportion of monomer (a) to the oxazoline-containing copolymer is 28.0wt%, the proportion of ethylenically unsaturated monomer (b) to the oxazoline-containing copolymer is 44.0wt%, and the proportion of ethylenically unsaturated monomer (c) to the oxazoline-containing copolymer is 28.0wt%.

[0105] The solid content of the water-based oxazoline crosslinker D5 of this embodiment is 40%, and the equivalent weight (based on solids) of oxazoline is 268. In the water-based oxazoline crosslinker D5 of this embodiment, water accounts for 44.3wt% of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7wt% of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0106] The water-based oxazoline crosslinker D5 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0107] Example 6

[0108] This embodiment provides a water-based oxazoline crosslinker D6, which is prepared by the following process:

[0109] (1) Preparation of carboxyl-containing polyether G6:

[0110] The reaction flask was purged with nitrogen, and 750 g of Clariant M750 (polyethylene glycol monomethyl ether, 750 molecular weight) and 148.1 g of phthalic anhydride were added. The mixture was heated to 120° C. and reacted for 4 h. Infrared spectrum detection showed that the hydroxyl groups were almost completely converted to obtain a product (i.e., carboxyl-containing polyether G6). The acid value was 62 mg KOH / g, and the calculated carboxyl equivalent weight was approximately 898.

[0111] Among them, the carboxyl-containing polyether G6 satisfies the general formula (2), and R2 is hydrogen, R3 is methyl, and the average value of y is is 15.3, x is 1, and Z is a divalent aromatic hydrocarbon group of 6 carbon atoms represented by formula (4):

[0112]

[0113] (2) Preparation of water-based oxazoline crosslinker D6:

[0114] The reaction flask was purged with nitrogen, and 25.0 g of carboxyl polyether G6, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added and heated to 80°C. 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (47.0 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate within 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D6.

[0115] Wherein, ethylenically unsaturated monomer (b) is excessive with respect to carboxyl-containing polyether G6, and the acid value detected is zero, indicating that carboxyl-containing polyether G6 has completely reacted with the oxazoline group in ethylenically unsaturated monomer (b). During the reaction process, a ring-opening reaction (forming ethylenically unsaturated monomer (c)) of carboxyl-containing polyether G6 and ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds (olefinic bonds) between the monomers simultaneously occur between monomer (a), ethylenically unsaturated monomer (b), and carboxyl-containing polyether G6, thereby obtaining a copolymer containing oxazoline groups.

[0116] In the oxazoline-containing copolymer, the proportion of monomer (a) to the oxazoline-containing copolymer is 28.0 wt%, the proportion of ethylenically unsaturated monomer (b) to the oxazoline-containing copolymer is 43.9 wt%, and the proportion of ethylenically unsaturated monomer (c) to the oxazoline-containing copolymer is 28.1 wt%.

[0117] The solid content of the water-based oxazoline crosslinker D6 of this embodiment is 40%, and the equivalent weight (based on solids) of oxazoline is 268. In the water-based oxazoline crosslinker D6 of this embodiment, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0118] The water-based oxazoline crosslinker D6 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0119] Example 7

[0120] This embodiment provides a water-based oxazoline crosslinker D7, which is prepared by the following process:

[0121] (1) Preparation of ethylenically unsaturated monomer (c1):

[0122] In a reaction flask, add ethylenically unsaturated monomer (b) (111.1 g 2-isopropenyl-2-oxazoline), 780.0 g carboxyl polyether G1, and 0.45 g p-methoxyphenol. Heat to 90°C and react for 10 h. The acid value is zero. The resulting light yellow transparent liquid is ethylenically unsaturated monomer (c1).

[0123] Wherein, the ethylenically unsaturated monomer (c1) satisfies the general formula (1), and R1 is methyl, R2 is hydrogen, R3 is methyl, Z is methylene, and the average value of y is is 15.3, x is 0.

[0124] (2) Preparation of water-based oxazoline crosslinker D7:

[0125] A reaction flask was purged with nitrogen, and 79.5 g of water and 79.5 g of propylene glycol methyl ether were added. The flask was heated to 80°C, and 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate), the ethylenically unsaturated monomer (b) (43.4 g of 2-isopropenyl-2-oxazoline), and 28.6 g of the ethylenically unsaturated monomer (c1) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate over 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D7.

[0126] During the reaction, a polymerization reaction of unsaturated double bonds (olefinic bonds) occurs between the monomer (a), the ethylenically unsaturated monomer (b), and the ethylenically unsaturated monomer (c1), thereby obtaining a copolymer containing an oxazoline group.

[0127] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 28.0 wt%, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 43.4 wt%, and the proportion of ethylenically unsaturated monomer (c1) in the oxazoline-containing copolymer is 28.6 wt%.

[0128] The solid content of the water-based oxazoline crosslinking agent D7 of this embodiment is 40%, and the equivalent weight (based on solids) of oxazoline is 271. In the water-based oxazoline crosslinking agent D7 of this embodiment, water accounts for 44.3wt% of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7wt% of the total amount of the oxazoline-containing copolymer, water and organic solvent.

[0129] The water-based oxazoline crosslinker D7 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0130] Example 8

[0131] This embodiment provides a water-based oxazoline crosslinker D8, which is prepared by the following process:

[0132] (1) Preparation of ethylenically unsaturated monomer (c2):

[0133] In a reaction flask, add ethylenically unsaturated monomer (b) (97.1 g 2-vinyl-2-oxazoline), 780.0 g carboxyl polyether G1, and 0.45 g p-methoxyphenol. Heat to 90°C and react for 10 h. The acid value is zero. The resulting light yellow transparent liquid is ethylenically unsaturated monomer (c2).

[0134] Wherein, the ethylenically unsaturated monomer (c2) satisfies the general formula (1), and R1 is hydrogen, R2 is hydrogen, R3 is methyl, Z is methylene, and the average value of y is is 15.3, x is 0.

[0135] (2) Preparation of water-based oxazoline crosslinker D8:

[0136] The reaction flask was purged with nitrogen, 159.0 g of water was added, and the mixture was heated to 80°C. 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate), the ethylenically unsaturated monomer (b) (43.4 g of 2-vinyl-2-oxazoline), and 28.6 g of the ethylenically unsaturated monomer (c2) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate over 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D8.

[0137] During the reaction, a polymerization reaction of unsaturated double bonds (olefinic bonds) occurs between the monomer (a), the ethylenically unsaturated monomer (b), and the ethylenically unsaturated monomer (c2), thereby obtaining a copolymer containing an oxazoline group.

[0138] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 28.0 wt%, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 43.4 wt%, and the proportion of ethylenically unsaturated monomer (c2) in the oxazoline-containing copolymer is 28.6 wt%.

[0139] The solid content of the aqueous oxazoline crosslinker D8 of this embodiment is 40%, and the equivalent weight of oxazoline (based on solids) is 237. In the aqueous oxazoline crosslinker D8 of this embodiment, water accounts for 61.4 wt % of the total weight of the oxazoline-containing copolymer and water.

[0140] The water-based oxazoline crosslinker D8 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0141] Example 9

[0142] This embodiment provides a water-based oxazoline crosslinker D9, which is prepared by the following process:

[0143] The reaction flask was purged with nitrogen, and 27.0 g of carboxyl polyether G1, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added. The flask was heated to 80°C, and 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The ethylenically unsaturated monomer (b) (73.0 g of 2-isopropenyl-2-oxazoline) was uniformly added dropwise to the reaction vessel over 2 h, maintaining the reaction temperature at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero, and the resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D9.

[0144] Wherein, the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G1, and the detected acid value is zero, indicating that the carboxyl-containing polyether G1 has completely reacted with the oxazoline group in the ethylenically unsaturated monomer (b). During the reaction process, a ring-opening reaction (forming ethylenically unsaturated monomer (c)) between the carboxyl-containing polyether G1 and the ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds (olefinic bonds) between the monomers simultaneously occur between the ethylenically unsaturated monomer (b) and the carboxyl-containing polyether G1, thereby obtaining a copolymer containing an oxazoline group.

[0145] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 0 wt%, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 69.2 wt%, and the proportion of ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 30.8 wt%.

[0146] The solid content of the water-based oxazoline crosslinker D9 of this embodiment is 40%, and the equivalent weight (based on solids) of oxazoline is 170. In the water-based oxazoline crosslinker D9 of this embodiment, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0147] The water-based oxazoline crosslinker D9 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0148] Example 10

[0149] This embodiment provides a water-based oxazoline crosslinker D10, which is prepared by the following process:

[0150] The reaction flask was purged with nitrogen, and 13.5 g of carboxyl polyether G1, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added. The mixture was heated to 80°C, and 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (39.3 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (47.2 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate over 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker D10.

[0151] Wherein, the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G1, and the detected acid value is zero, indicating that the carboxyl-containing polyether G1 has completely reacted with the oxazoline group in the ethylenically unsaturated monomer (b). During the reaction process, a ring-opening reaction (forming ethylenically unsaturated monomer (c)) between the carboxyl-containing polyether G1 and the ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds (olefinic bonds) between the monomers simultaneously occur between the monomer (a), the ethylenically unsaturated monomer (b), and the carboxyl-containing polyether G1, thereby obtaining a copolymer containing an oxazoline group.

[0152] In the oxazoline-containing copolymer, the proportion of monomer (a) to the oxazoline-containing copolymer is 39.3wt%, the proportion of ethylenically unsaturated monomer (b) to the oxazoline-containing copolymer is 45.3wt%, and the proportion of ethylenically unsaturated monomer (c) to the oxazoline-containing copolymer is 15.4wt%.

[0153] The solid content of the water-based oxazoline crosslinker D10 of this embodiment is 40%, and the equivalent weight (based on solids) of oxazoline is 260. In the water-based oxazoline crosslinker D10 of this embodiment, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0154] The water-based oxazoline crosslinker D10 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0155] Example 11

[0156] This embodiment provides a water-based oxazoline crosslinker D11, which is prepared by the following process:

[0157] A reaction flask was purged with nitrogen, and 43.0 g of carboxyl polyether G1, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added. The flask was heated to 80°C, and 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (9.8 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (47.2 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate over 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the flask was kept warm at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the water-based oxazoline crosslinker D11.

[0158] Wherein, the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G1, and the detected acid value is zero, indicating that the carboxyl-containing polyether G1 has completely reacted with the oxazoline group in the ethylenically unsaturated monomer (b). During the reaction process, a ring-opening reaction (forming ethylenically unsaturated monomer (c)) between the carboxyl-containing polyether G1 and the ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds (olefinic bonds) between the monomers simultaneously occur between the monomer (a), the ethylenically unsaturated monomer (b), and the carboxyl-containing polyether G1, thereby obtaining a copolymer containing an oxazoline group.

[0159] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 9.8 wt %, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 41.1 wt %, and the proportion of ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 49.1 wt %.

[0160] The solid content of the water-based oxazoline crosslinker D11 of this embodiment is 40%, and the equivalent weight of oxazoline (based on solids) is 287. In the water-based oxazoline crosslinker D11 of this embodiment, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0161] The water-based oxazoline crosslinker D11 obtained in this example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0162] Comparative Example 1

[0163] This comparative example provides a water-based oxazoline crosslinker E1, which is prepared by the following process:

[0164] The reaction flask was purged with nitrogen, and 79.5 g of water and 79.5 g of propylene glycol methyl ether were added. The flask was heated to 80°C, and 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (72.0 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate over 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the flask was kept warm at 80±2°C for 10 h. The resulting light yellow transparent liquid was the water-based oxazoline crosslinker E1.

[0165] During the reaction, a polymerization reaction of unsaturated double bonds occurs between the monomer (a) and the ethylenically unsaturated monomer (b), thereby obtaining a copolymer containing an oxazoline group.

[0166] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 28.0 wt %, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 72.0 wt %, and the proportion of ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 0 wt %.

[0167] The solid content of the aqueous oxazoline crosslinker E1 of this comparative example is 40%, and the equivalent weight of oxazoline (based on solids) is 163. In the aqueous oxazoline crosslinker E1 of this comparative example, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and the organic solvent.

[0168] The aqueous oxazoline crosslinker E1 obtained in this comparative example was diluted in deionized water at a mass ratio of 1:10 to obtain a turbid solution that could not be stably stored, indicating that it had poor water dilutability.

[0169] Comparative Example 2

[0170] This comparative example provides a water-based oxazoline crosslinker E2, which is prepared by the following process:

[0171] The reaction flask was purged with nitrogen, and 10.0 g of carboxyl polyether G1, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added. The mixture was heated to 80°C, and 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (62.0 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate within 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker E2.

[0172] Wherein, the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G1, and the detected acid value is zero, indicating that the carboxyl-containing polyether G1 has completely reacted with the oxazoline group in the ethylenically unsaturated monomer (b). During the reaction process, a ring-opening reaction (forming ethylenically unsaturated monomer (c)) between the carboxyl-containing polyether G1 and the ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds (olefinic bonds) between the monomers simultaneously occur between the monomer (a), the ethylenically unsaturated monomer (b), and the carboxyl-containing polyether G1, thereby obtaining a copolymer containing an oxazoline group.

[0173] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 28.0 wt%, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 60.6 wt%, and the proportion of ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 11.4 wt%.

[0174] The solid content of the aqueous oxazoline crosslinker E2 of this comparative example is 40%, and the equivalent weight (based on solids) of oxazoline is 194. In the aqueous oxazoline crosslinker E2 of this comparative example, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and organic solvent.

[0175] The aqueous oxazoline crosslinker E2 obtained in this comparative example was diluted in deionized water at a mass ratio of 1:10 to obtain a turbid solution that could not be stably stored, indicating that it had poor water dilution.

[0176] Comparative Example 3

[0177] This comparative example provides a water-based oxazoline crosslinker E3, which is prepared by the following process:

[0178] The reaction flask was purged with nitrogen, and 53.5 g of carboxyl polyether G1, 79.5 g of water, and 79.5 g of propylene glycol methyl ether were added and heated to 80°C. 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (9.8 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (36.7 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate within 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker E3.

[0179] Wherein, the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G1, and the detected acid value is zero, indicating that the carboxyl-containing polyether G1 has completely reacted with the oxazoline group in the ethylenically unsaturated monomer (b). During the reaction process, a ring-opening reaction (forming ethylenically unsaturated monomer (c)) between the carboxyl-containing polyether G1 and the ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds (olefinic bonds) between the monomers simultaneously occur between the monomer (a), the ethylenically unsaturated monomer (b), and the carboxyl-containing polyether G1, thereby obtaining a copolymer containing an oxazoline group.

[0180] In the oxazoline-containing copolymer, the proportion of monomer (a) in the oxazoline-containing copolymer is 9.8 wt %, the proportion of ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 29.1 wt %, and the proportion of ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 61.1 wt %.

[0181] The solid content of the aqueous oxazoline crosslinker E3 of this comparative example is 40%, and the equivalent weight (based on solids) of oxazoline is 397. In the aqueous oxazoline crosslinker E3 of this comparative example, water accounts for 44.3 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and the organic solvent.

[0182] The aqueous oxazoline crosslinker E3 obtained in this comparative example was diluted in deionized water at a mass ratio of 1:10 to obtain a clear and transparent solution, indicating that it has excellent water dilutability.

[0183] Comparative Example 4

[0184] This comparative example provides a water-based oxazoline crosslinker E4, which is prepared by the following process:

[0185] (1) Preparation of carboxyl-containing polyether H1:

[0186] The reaction flask is filled with nitrogen, and 52.0g of tetraethylene glycol monomethyl ether, 39.0g of 2,2,6,6-tetramethylpiperidinyl oxide (TEMPO, Aladdin Chemical Reagent) and 300.0g of dichloromethane are added, and heated to reflux and passed through with dry air. 15.6g of concentrated nitric acid is added, and 15min is added, and then the mixture is heated at reflux for 17h. 150.0g of isopropyl alcohol is then added and stirred for 1h. The volatile component is removed by vacuum and obtained 50.1g of product (i.e., carboxyl-containing resin H1). The test acid number is 253mgKOH / g, and the calculated carboxyl equivalent is about 222.

[0187] Among them, the carboxyl-containing polyether H1 satisfies the general formula (2), and R2 is hydrogen, R3 is methyl, Z is methylene, and the average value of y is is 4, x is 0.

[0188] (2) Preparation of water-based oxazoline crosslinker E4:

[0189] The reaction flask was purged with nitrogen, and 17.7 g of carboxyl polyether H1, 74 g of water, and 74 g of propylene glycol methyl ether were added. The mixture was heated to 80°C, and 6.0 g of 2,2'-azobis(2-amidinopropane) dihydrochloride was added. The monomer (a) (28.0 g of methyl methacrylate) and the ethylenically unsaturated monomer (b) (47.0 g of 2-isopropenyl-2-oxazoline) were mixed uniformly and added dropwise to the reaction vessel at a uniform rate over 2 h. The reaction temperature was maintained at 80±2°C. After the addition was complete, the mixture was kept at 80±2°C for 10 h. The acid value was detected to be zero. The resulting light yellow transparent liquid was the aqueous oxazoline crosslinker E4.

[0190] The ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether H1, and the detected acid value is zero, indicating that the carboxyl-containing polyether H1 has completely reacted with the oxazoline group in the ethylenically unsaturated monomer (b). During the reaction process, a ring-opening reaction (forming ethylenically unsaturated monomer (c')) between the carboxyl-containing polyether H1 and the ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds (olefinic bonds) between the monomers simultaneously occur between the monomer (a), the ethylenically unsaturated monomer (b), and the carboxyl-containing polyether H1, thereby obtaining an oxazoline-containing copolymer.

[0191] In the oxazoline-containing copolymer, the proportion of monomer (a) to the oxazoline-containing copolymer is 30.2 wt%, the proportion of ethylenically unsaturated monomer (b) to the oxazoline-containing copolymer is 41.1 wt%, and the proportion of ethylenically unsaturated monomer (c') to the oxazoline-containing copolymer is 28.7 wt%.

[0192] The solid content of the aqueous oxazoline crosslinker E4 of this comparative example is 40%, and the equivalent weight of oxazoline (based on solids) is 287. In the aqueous oxazoline crosslinker E4 of this comparative example, water accounts for 44.4 wt % of the total amount of the oxazoline-containing copolymer and water, and the organic solvent accounts for 30.7 wt % of the total amount of the oxazoline-containing copolymer, water, and the organic solvent.

[0193] The aqueous oxazoline crosslinker E4 obtained in this comparative example was diluted in deionized water at a mass ratio of 1:10 to obtain a turbid solution that could not be stably stored, indicating that it had poor water dilution.

[0194] Example 12

[0195] This embodiment provides an adhesive composition, comprising any one of the aqueous oxazoline crosslinkers D1-D11 of Examples 1-11, and an aqueous polyurethane dispersion (i.e., an aqueous resin containing a carboxyl group), wherein the solid content of the aqueous oxazoline crosslinker is 2 parts by weight (if the solid content of the aqueous oxazoline crosslinker is 40%, the amount of the composition added is 2 / 40% = 5 parts), and the weight of the aqueous polyurethane dispersion is 80 parts.

[0196] Example 13

[0197] This embodiment provides a water-based coating, comprising the following components in parts by weight: an aqueous oxazoline crosslinker according to any one of Embodiments 1-11; 80 parts of an aqueous polyurethane dispersion; 0.2 parts of an organosilicon defoamer; 0.5 parts of an organosilicon leveling agent; 0.5 parts of an acetylene glycol wetting and defoaming agent, 1 part of a dispersant, 3 parts of a matting powder, 6 parts of a film-forming aid; 0.5 parts of a thickener; and 3.3 parts of water.

[0198] The preparation method of the water-based paint of this embodiment includes the following steps: mixing the components uniformly to obtain the water-based paint.

[0199] Example 14

[0200] This embodiment provides a product coated with the water-based coating of embodiment 13.

[0201] The water-based coatings in Example 13, i.e., the water-based coatings formed by the water-based oxazoline crosslinking agents in Examples 1-11, were applied to the surface of the PVC substrate to form a coating film with a thickness of 10±2 μm on the surface of the PVC substrate.

[0202] Performance Testing

[0203] The performance of the water-based oxazoline crosslinker of Examples 1-11 and Comparative Example 3 was tested as follows:

[0204] The water-based oxazoline crosslinkers D1-D11 and E3 of Examples 1-11 and Comparative Example 3 were respectively formulated into water-based coatings 1-12 with commercial water-based polyurethane dispersions (trade name PU-7012, Guangzhou Guanzhi New Materials, solid content: 35%) according to the formula in Table 1, and compared with water-based coating 13 (blank) without adding water-based oxazoline crosslinkers.

[0205] Table 1 Water-based coating formula

[0206]

[0207]

[0208]

[0209] The following performance tests were conducted on water-based coatings 1-13:

[0210] Construction and curing conditions: Apply water-based coatings 1-13 respectively on the surface of PVC substrates, bake in a forced air oven at 120°C for 10 minutes, and after cooling to room temperature, form a coating film with a thickness of 10±2μm, and then perform performance testing.

[0211] Adhesion test: After applying 3M transparent tape, pull hard to observe the film's detachment from the substrate. Rating: 1-5, with 5 being the best (no detachment at all).

[0212] Hot water resistance test: Immerse the coating in boiling water at about 100°C for 1 minute, and then observe whether the coating turns white or has decreased adhesion. Score 1-5 points, with 5 points being the best (no whitening of the coating and no obvious decrease in adhesion).

[0213] The test results are shown in the following table:

[0214] Table 2 Test results of water-based coatings

[0215] Water-based paint Adhesion (grade) Hot water resistance (points) 1 5 5 2 5 5 3 5 5 4 5 5 5 5 5 6 5 5 7 5 5 8 5 5 9 5 5 10 5 5 11 5 4 12 5 2 13 3 1

[0216] The water-based coating formulas in Table 1 and the performance test results in Table 2 show that the water-based coatings 1-11 added with the water-based oxazoline crosslinkers D1-D11 of Examples 1-11 of the present invention have excellent water dilution, adhesion, and hot water resistance.

[0217] The active ingredient in the aqueous oxazoline crosslinker E1 of Comparative Example 1, ie, the copolymer containing an oxazoline group, does not contain an ethylenically unsaturated monomer (c) containing a polyether group, resulting in poor water dilution of the aqueous oxazoline crosslinker E1 of Comparative Example 1.

[0218] In the effective ingredient of the aqueous oxazoline crosslinker E2 of Comparative Example 2, i.e., the copolymer containing oxazoline groups, the proportion of the ethylenically unsaturated monomer (c) in the copolymer containing oxazoline groups is too low, resulting in poor water dilution of the aqueous oxazoline crosslinker E2 of Comparative Example 2.

[0219] In the effective ingredient of the water-based oxazoline crosslinker E3 of comparative example 3, i.e., the copolymer containing oxazoline groups, the proportion of the ethylenically unsaturated monomer (c) in the copolymer containing oxazoline groups is too high, resulting in the high hydrophilicity of the copolymer containing oxazoline groups itself; after the water-based oxazoline crosslinker E3 of comparative example 3 is configured into a water-based coating 12, the hot water resistance is poor, which affects the hot water resistance of the coating film.

[0220] The y value of the oxazoline group-containing copolymer, which is the active ingredient in the aqueous oxazoline crosslinker E4 of Comparative Example 4, is too low, resulting in poor water dilution of the aqueous oxazoline crosslinker E4 of Comparative Example 4.

[0221] The coating film formed by the water-based coating 13 without adding a water-based crosslinking agent has poor adhesion and hot water resistance.

[0222] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, and the present invention is intended to encompass such modifications and variations.

Claims

1. A copolymer containing an oxazoline group, characterized in that: Include: a) at least one monomer (a) selected from C1-20 alkyl (meth)acrylates and C8-20 vinyl aromatic compounds; b) at least one ethylenically unsaturated monomer (b), said ethylenically unsaturated monomer (b) comprising an oxazoline group; c) at least one ethylenically unsaturated monomer (c), said ethylenically unsaturated monomer (c) comprising a polyether group, and said ethylenically unsaturated monomer (c) having a structure of at least one of formula (1): In formula (1), R1 and R2 are each independently hydrogen or methyl; R3 is a hydrocarbon group having 1 to 8 carbon atoms; Z is a divalent aliphatic hydrocarbon group or aromatic hydrocarbon group having 1 to 8 carbon atoms; x is 0 or 1; y is 6 to 68; In the oxazoline-containing copolymer, the proportion of the monomer (a) in the oxazoline-containing copolymer is 0-40wt%, the proportion of the ethylenically unsaturated monomer (b) in the oxazoline-containing copolymer is 38-70wt%, and the proportion of the ethylenically unsaturated monomer (c) in the oxazoline-containing copolymer is 15-50wt%.

2. The oxazoline-containing copolymer according to claim 1, wherein: The ethylenically unsaturated monomer (c) is obtained by reacting a carboxyl-containing polyether G with the ethylenically unsaturated monomer (b); the structure of the carboxyl-containing polyether G is at least one of formula (2): In formula (2), R2 is hydrogen or methyl; R3 is a hydrocarbon group having 1 to 8 carbon atoms; Z is a divalent aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 8 carbon atoms; x is 0 or 1; and y is 6-68.

3. A method for preparing a copolymer containing an oxazoline group as described in any one of claims 1 to 2, characterized in that: The following steps are involved: The monomer (a), the ethylenically unsaturated monomer (b) and the ethylenically unsaturated monomer (c) are polymerized to obtain the above-mentioned monomer (a).

4. A method for preparing a copolymer containing an oxazoline group as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: The monomer (a), the ethylenically unsaturated monomer (b) and the carboxyl-containing polyether G are reacted to obtain the polyether, wherein the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G, and during the reaction, a ring-opening reaction between the carboxyl-containing polyether G and the ethylenically unsaturated monomer (b) and a polymerization reaction of the unsaturated double bonds of each monomer occur; The structure of the carboxyl-containing polyether G is at least one of formula (2): In formula (2), R2 is hydrogen or methyl; R3 is a hydrocarbon group having 1 to 8 carbon atoms; Z is a divalent aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 8 carbon atoms; x is 0 or 1; and y is 6-68.

5. An aqueous oxazoline crosslinking agent, characterized in that: The method comprises the oxazoline-containing copolymer according to any one of claims 1 to 2 and water, wherein the water accounts for 30-90 wt % of the total amount of the oxazoline-containing copolymer and the water.

6. The aqueous oxazoline crosslinking agent according to claim 5, wherein: The composition further comprises an organic solvent, which accounts for 5-50 wt % of the total amount of the oxazoline-containing copolymer, water and the organic solvent.

7. A method for preparing an aqueous oxazoline crosslinking agent as claimed in any one of claims 5 to 6, characterized in that: The following steps are involved: Water or water and an organic solvent are added to a reaction container, and an initiator is added, and the mixture is heated to 50-90° C., and the monomer (a), the ethylenically unsaturated monomer (b) and the ethylenically unsaturated monomer (c) are added to the reaction container for reaction to finally obtain the water-based oxazoline crosslinker.

8. A method for preparing an aqueous oxazoline crosslinking agent as claimed in any one of claims 5 to 6, characterized in that: The following steps are involved: The carboxyl-containing polyether G is added to a container, water or water and an organic solvent is added, and an initiator is added, and the mixture is heated to 50-90° C., and a mixture of the monomer (a) and the ethylenically unsaturated monomer (b) is added to the reaction container for reaction, wherein the ethylenically unsaturated monomer (b) is in excess relative to the carboxyl-containing polyether G, to finally obtain the water-based oxazoline crosslinking agent; The structure of the carboxyl-containing polyether G is at least one of formula (2): In formula (2), R2 is hydrogen or methyl; R3 is a hydrocarbon group having 1 to 8 carbon atoms; Z is a divalent aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 8 carbon atoms; x is 0 or 1; and y is 6-68.

9. A water-based coating, ink or adhesive composition, characterized in that: The method comprises the water-based oxazoline crosslinking agent according to any one of claims 5 to 6 and a carboxyl-containing water-based resin, wherein the water-based oxazoline crosslinking agent accounts for 2-10 wt % of the carboxyl-containing water-based resin.

10. An article coated with the aqueous coating, ink or adhesive composition according to claim 9.

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