An oxazoline group-containing copolymer, a preparation method, an application, and a composition

Abstract

The application discloses an oxazoline group-containing copolymer, a preparation method, application and composition. The oxazoline group-containing copolymer comprises: a) at least one ethylenically unsaturated monomer A comprising at least one 2-substituted oxazoline group; b) at least one monomer B selected from acrylic acid C 1‑20‑ alkyl ester or C 8‑20‑ vinyl aromatic compound; c) an acrylic acid salt; wherein the mass fraction of the monomer A is 40-90 parts, the mass fraction of the monomer B is 10-40 parts, and the mass fraction of the acrylic acid salt is 5-30 parts. The preparation process of the oxazoline group-containing copolymer has the characteristics of low-temperature initiation, mild reaction conditions, low energy consumption and easy operation; the oxazoline group-containing copolymer has excellent adhesion and high viscosity. The oxazoline group-containing copolymer as a crosslinking agent can effectively improve the hydrolysis resistance and thermal stability of high-molecular polymer containing groups such as carboxyl, acid anhydride, epoxy, phenol, mercapto and halogen.

Description

Technical Field

[0001] This invention relates to an oxazoline-containing copolymer, its preparation method, its application, and its composition. Background Technology

[0002] Acrylic polymers are widely used in coatings, adhesives, rubber products, and plastic cushioning agents. The initiation system for these polymers generally employs two methods: thermal initiation and redox initiation. Thermal initiation involves higher reaction temperatures, greater operational requirements, and higher energy consumption. Furthermore, the post-processing of oil-soluble initiators inevitably generates some toxic substances, hindering the green and environmentally friendly production of the products. Moreover, the polymerization process of acrylic solutions / emulsions is a strongly exothermic reaction. If conditions are not properly controlled or operational errors occur during production, heat can easily accumulate and pressure can rise within the reactor, leading to uncontrolled polymerization.

[0003] Traditional coating materials are primarily solvent-based, and the emission of volatile organic compounds (VOCs) from these materials is harmful to human health and the environment. With increasing environmental awareness and the establishment of environmental regulations, traditional solvent-based coating materials are facing growing restrictions. Therefore, low-pollution, environmentally friendly water-based coating materials are becoming increasingly important. Water-based coating materials only achieve coating properties comparable to solvent-based coating materials, such as water resistance, acid and alkali resistance, and thermal stability, after their film undergoes cross-linking and curing. Therefore, the quality of the cross-linking agent directly affects the quality of the coating material.

[0004] Reactive polyacrylate crosslinking agents are polyacrylates with active functional groups on their main chain. They are obtained by modifying polyacrylate along the polymer main chain with reactive oxazoline. Oxazoline is a five-membered heterocycle containing nitrogen and oxygen. Because the oxazoline ring can chemically react with polymers containing carboxylic acids, acid anhydrides, epoxy groups, phenolic groups, mercapto groups, halogen groups, etc., to produce crosslinking effects, it significantly improves the polymer's thermal stability and hydrolysis resistance, and the reaction does not produce toxic byproducts, making it more environmentally friendly.

[0005] However, while existing polyacrylate crosslinking agents containing reactive oxazoline groups have a certain degree of hydrolysis resistance, their adhesiveness and adhesion are poor. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an environmentally friendly oxazoline-containing copolymer, its preparation method, applications, and compositions. The preparation process of the oxazoline-containing copolymer of the present invention features low-temperature initiation, mild reaction conditions, low energy consumption, and ease of operation; it exhibits excellent adhesion and high viscosity. Using the oxazoline-containing copolymer of the present invention as a crosslinking agent can effectively improve the hydrolysis resistance and thermal stability of polymers containing carboxyl, acid anhydride, epoxy, phenolic, mercapto, and halogen groups.

[0007] The technical problem solved by this invention is addressed by the following technical solution.

[0008] This invention provides a copolymer containing an oxazoline group, comprising (as a structural unit): a) At least one olefinic unsaturated monomer A, which contains at least one 2-substituted oxazoline group; b) At least one selected from acrylic acid C 1-20- Alkyl esters or C 8-20- Monomer B of vinyl aromatic compounds; c) Acrylates; The monomer A is present in a mass fraction of 40-90 parts, the monomer B is present in a mass fraction of 10-40 parts, and the acrylate is present in a mass fraction of 5-30 parts.

[0009] In the context of this invention, an oxazoline group refers to a heterocyclic compound comprising a five-membered ring containing exactly one oxygen atom and exactly one nitrogen atom. Specifically, the oxazoline group is a 2-oxazoline group, which can be described by the following structural units.

[0010]

[0011] In some preferred embodiments of the present invention, the monomer A is a compound as shown in formula (I). (I), The group has the following meanings: R1 is a C that contains at least one olefinic unsaturated group. 2-20- alkenyl; R2, R3, R4, and R5 are independently selected from H, halogens, and C. 1-20 -alkyl, C 2-20 -Alkenyl, C 6-20 -Aryl, C 7-32 -Arylalkyl, C 1-20 -Hydroxyalkyl, C 1-20 -aminoalkyl and C 1-20 - Haloalkyl group, preferably selected from H, halogen and C 1-20 -alkyl.

[0012] An alkene-type unsaturated group refers to a terminal C=C double bond.

[0013] Alkyl refers to a monovalent group consisting of a straight-chain, branched, or cyclic hydrocarbon group, preferably a straight-chain or branched hydrocarbon chain, particularly a straight-chain or branched hydrocarbon chain containing 1 to 20 carbon atoms, preferably 1 to 18 carbon atoms, and especially preferably 1 to 12 carbon atoms. For example, an alkyl group can be methyl, ethyl, n-propyl, or isopropyl.

[0014] An alkenyl group refers to a monovalent group composed of a straight-chain or branched hydrocarbon chain, such as a straight-chain or branched hydrocarbon chain containing 2 to 20 carbon atoms, preferably 2 to 18 carbon atoms, particularly preferably 2 to 12 carbon atoms, containing one or more C=C double bonds, wherein the C=C double bonds may be within the hydrocarbon chain or at the end of the hydrocarbon chain (terminal C=C double bonds). For example, an alkenyl group may be allyl or vinyl.

[0015] Aryl refers to a substituted or unsubstituted aromatic hydrocarbon group, such as a substituted or unsubstituted aromatic hydrocarbon group containing 6 to 20 carbon atoms. For example, an aryl group can be phenyl.

[0016] Arylalkyl refers to a monovalent group derived from a straight-chain or branched alkyl group, such as a straight-chain or branched alkyl group containing 1 to 20 carbon atoms, preferably 2 to 18 carbon atoms, particularly preferably 2 to 12 carbon atoms, by replacing one or more hydrogen atoms with an aryl group, wherein the aryl group is a substituted or unsubstituted aromatic hydrocarbon group, particularly a substituted or unsubstituted aromatic hydrocarbon group containing 6 to 14 carbon atoms. For example, the aromatic hydrocarbon group may be phenyl; for example, the arylalkyl group may be benzyl.

[0017] Halogen refers to a substituent selected from fluorine, chlorine, bromine or iodine, with chlorine being preferred.

[0018] Halogenated alkyl refers to a monovalent group derived from a straight-chain or branched alkyl group, such as a straight-chain or branched alkyl group containing 2 to 20 carbon atoms, preferably 2 to 18 carbon atoms, particularly preferably 2 to 12 carbon atoms, by replacing one or more hydrogen atoms with halogen atoms (-F, -Cl, -Br, -I, especially Cl). This also applies to hydroxyalkyl and aminoalkyl groups.

[0019] Preferably, R1 is C 1-10 -Alkenyl, preferably C 1-6 -Alkenyl group, comprising at least one olefinically unsaturated group. In a preferred embodiment, group R1 comprises exactly one olefinically unsaturated group. Group R1 is particularly selected from vinyl, allyl, isopropenyl (2-propen-2-yl), 2-propen-1-yl, 3-buten-1-yl, or 4-buten-1-yl. Particularly preferred is vinyl or isopropenyl, especially isopropenyl.

[0020] Preferably, groups R2, R3, R4, and R5 are independently selected from H, halogens, and C. 1-10 -alkyl, C 6-12 -Aryl, C 7-13 -Arylalkyl, C 1-10 -alkoxy group, C 1-10 -Hydroxyalkyl, C 1-10 -aminoalkyl and C 1-10 - Haloalkyl; for example, selected from H and C 1-6-alkyl, particularly preferably selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl and n-hexyl, more preferably selected from H, methyl and ethyl.

[0021] In a preferred embodiment, at least two of groups R2, R3, R4, and R5 are H. In a preferred embodiment, groups R2 and R3 are H. In a preferred embodiment, groups R2, R3, R4, and R5 are all H. In a preferred embodiment, at least two of groups R2, R3, R4, and R5 are H.

[0022] In a preferred embodiment, groups R2, R3, R4 and R5 are independently selected from H, methyl and ethyl, and at least two of groups R2, R3, R4 and R5 are H, preferably groups R2 and R3 are H.

[0023] In some preferred embodiments of the invention, monomer A is a 2-substituted oxazoline compound comprising an olefinically unsaturated monomer; particularly preferably, monomer A is at least one monomer selected from the group consisting of: 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-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 p-styryl-2-oxazoline. 2-vinyl-2-oxazoline (VOXA) and / or 2-isopropenyl-2-oxazoline (IPOX) are particularly preferred.

[0024] In some preferred embodiments of the present invention, the monomer A is 50-80 parts by mass, for example 70 or 80 parts.

[0025] In some preferred embodiments of the invention, the monomer A is present in an amount ranging from 50.0 to 98.0% by weight, preferably from 50.5 to 85.0% by weight, particularly preferably from 55.0 to 72.0% by weight, based on the total amount of monomer in the oxazoline-containing copolymer.

[0026] In some preferred embodiments of the invention, monomer A is present in an amount ranging from 60.0 to 70.0% by weight, for example 63.64% or 66.67%, based on the total amount of monomer in the oxazoline-containing copolymer.

[0027] In some preferred embodiments of the present invention, monomer B is selected from at least one of the following monomers: (meth)acrylic acid C 1-20-alkyl esters, especially (meth)acrylic acid C 1-12 -Alkyl ester, particularly preferred (meth)acrylate C 1-8 -Alkyl ester.

[0028] In the context of this invention, the term "(meth)acryloyl" includes the corresponding acrylate and / or methacrylate or acrylate derivative and / or methacrylate derivative. For example, the term "(meth)acrylate" includes methyl acrylate and / or methyl methacrylate. For example, the term "(meth)acrylamide" includes acrylamide and / or methacrylamide.

[0029] In some alternative embodiments of the present invention, the monomer B is selected from C. 8-20 -Vinyl aromatic compounds, especially C 8-10 -Vinyl aromatic compounds.

[0030] In some embodiments of the invention, monomer B is at least one monomer or monomer composition selected from alkyl acrylates or vinyl aromatic compounds; particularly preferably, monomer B is at least one monomer selected from: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, sec-butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, styrene, α-methylstyrene and vinyltoluene, sodium styrene sulfonate. Methyl acrylate, methyl methacrylate, n-butyl acrylate and butyl methacrylate are particularly preferred.

[0031] In some preferred embodiments of the present invention, the monomer B is 15-40 parts by mass, for example 15 parts, 20 parts or 30 parts.

[0032] In some preferred embodiments of the invention, the monomer B is present in an amount ranging from 1.0 to 45.0% by weight, preferably from 10.0 to 39.5% by weight, particularly preferably from 15.0 to 35.0% by weight, based on the total amount of monomer in the oxazoline-containing copolymer.

[0033] In some preferred embodiments of the invention, the monomer B is present in an amount ranging from 20.0 to 30.0% by weight, for example 25.0% or 27.27%, based on the total amount of monomer in the oxazoline-containing copolymer.

[0034] In some preferred embodiments of the present invention, the monomer B comprises methyl methacrylate and n-butyl acrylate, wherein the mass ratio of methyl methacrylate to n-butyl acrylate may be (0.5-1.5):1, for example 1:1.

[0035] In one embodiment of the invention, the acrylate is present in a completely deprotonated form.

[0036] In one embodiment of the present invention, the acrylate is acrylic acid in the form of an alkaline earth metal salt.

[0037] In one embodiment of the invention, the solution containing the acrylate has a pH > 7, for example, a pH of 9.

[0038] In one embodiment of the present invention, the acrylate is prepared by mixing acrylic acid and an alkaline substance.

[0039] In one embodiment of the present invention, the acrylate is prepared by mixing acrylic acid and a pH buffer. The pH buffer may be an alkaline inorganic salt or an organic amine, such as ethylenediamine.

[0040] In some preferred embodiments of the present invention, the acrylate is in the amount of 5-15 parts by mass, for example, 10 parts.

[0041] In some preferred embodiments of the invention, the acrylate is present in an amount ranging from 0.1 to 25.0% by weight, preferably from 1.0 to 20.0% by weight, particularly preferably from 5.0 to 19.5% by weight, based on the total amount of monomers in the oxazoline-containing copolymer.

[0042] In some preferred embodiments of the invention, the acrylate is present in an amount ranging from 5% to 10% by weight, for example 9.09% or 8.33%, based on the total amount of monomers in the oxazoline-containing copolymer.

[0043] In one embodiment of the invention, the oxazoline-containing copolymer has a pH ≥ 6.5, for example 6.8, 7.9, 8.0 or 8.2.

[0044] In one embodiment of the present invention, the copolymer containing oxazoline groups is a liquid.

[0045] In one embodiment of the invention, the viscosity of the oxazoline-containing copolymer is ≥300 mPa·s (25°C) and ≤1500 mPa·s, for example 362 mPa·s, 341 mPa·s, 325 mPa·s or 371 mPa·s.

[0046] The viscosity can be measured using a Brookfield DVS+ rotational viscometer.

[0047] In one embodiment of the present invention, the oxazoline-containing copolymer forms a continuous sheet-like film.

[0048] The present invention also provides a method for preparing an oxazoline-containing copolymer, comprising the following steps: The following monomers are polymerized in the presence of a solvent and a redox agent C: a) at least one olefinic unsaturated monomer A, which contains at least one 2-substituted oxazoline group; b) At least one of the following selected from acrylic acid C 1-20- Alkyl esters or C 8-20- Monomer B of vinyl aromatic compounds; c) Acrylates; in: (1) In the redox agent C, the molar ratio of oxidant to reductant is 1:(0.8-1.2); (2) Monomer A: 40-90 parts by weight, Monomer B: 10-40 parts by weight, Acrylate: 5-30 parts by weight, Redox Agent C: 1-10 parts by weight; (3) The monomer A, the monomer B and the acrylate are added dropwise or mixed and added dropwise to the mixture of the solvent and the redox agent C; (4) The polymerization reaction temperature is 5-40℃.

[0049] In some alternative embodiments of the present invention, the type of monomer A may be as described above.

[0050] In some optional embodiments of the present invention, the monomer A is 50-80 parts by mass, for example 70 or 80 parts.

[0051] In some alternative embodiments of the present invention, the type of monomer B may be as described above.

[0052] In some optional embodiments of the present invention, the monomer B is 15-40 parts by mass, for example 15 parts, 20 parts or 30 parts.

[0053] In some alternative embodiments of the present invention, the solvent is water, such as deionized water.

[0054] In some optional embodiments of the present invention, the solvent is 100-400 parts by mass, for example 200-400 parts.

[0055] In this invention, the redox agent C is a mixed system containing an oxidant and a reducing agent.

[0056] In some optional embodiments of the present invention, the redox agent C is selected from: persulfate / hydrogen peroxide + reducing agent system, organic peroxide / organic hydrogen peroxide + reducing agent system, or transition metal oxide + reducing agent system.

[0057] In some alternative embodiments of the present invention, the persulfate in the redox agent C is selected from at least one of the following combinations: ammonium persulfate, potassium persulfate, and sodium persulfate.

[0058] In some optional embodiments of the present invention, the organic peroxide in the redox agent C is selected from at least one of the following combinations: benzoyl peroxide, N,N-dimethyltoluidine, N,N-dimethyl-p-toluidine, cumene hydroperoxide, or N,N-dimethyl-p-toluidine, etc.

[0059] In some optional embodiments of the present invention, the oxidizing agent C is particularly preferably potassium persulfate or cumene hydrogen peroxide.

[0060] In some optional embodiments of the present invention, the reducing agent C is selected from at least one of the following combinations: sodium thiosulfate, sodium bisulfite, sodium sulfite, ferrous sulfate, sodium metabisulfite, sodium formaldehyde sulfoxylate, ascorbic acid, ethylenediamine, sodium ethylenediaminetetraacetate, glycine, N-isopropylhydroxylamine, etc., with sodium bisulfite, ferrous sulfate and N-isopropylhydroxylamine being particularly preferred.

[0061] In some optional embodiments of the present invention, the redox agent C is 5-10 parts by mass, for example 6 parts, 7 parts or 9 parts.

[0062] In some preferred embodiments of the present invention, the molar ratio of oxidant to reducing agent C is 1:(0.9-1.0), for example 1:0.9 or 1:1.0.

[0063] In some optional embodiments of the present invention, an air purging stage may be included before polymerization, for example, first evacuating the reactor using a vacuum pump, then introducing nitrogen gas, repeating this process three times. Optionally, after the air in the reactor has been completely removed, water and the redox agent C are added to the reactor and stirred until dissolved.

[0064] In some preferred embodiments of the present invention, the system temperature can be maintained at 5-30°C during the dripping stage, and the mixture of monomer A and monomer B is added to the reactor in a dripping manner, with the dripping time controlled at 1-5 hours.

[0065] In some alternative embodiments of the present invention, the system temperature can be maintained at 10-20°C, for example 15°C or 20°C, during the dropping stage.

[0066] In some optional embodiments of the present invention, the dripping time can be controlled to be 2-3 hours.

[0067] In some optional embodiments of the present invention, after the mixture of monomer A and monomer B is added dropwise, the reaction is carried out at a constant temperature for 2-7 hours to terminate the reaction. After the reaction is completed, the mixture is removed and filtered to obtain the oxazoline-containing copolymer of the present invention.

[0068] In some optional embodiments of the present invention, after the mixture of monomer A and monomer B is added dropwise, the constant temperature reaction time is 4-6 hours.

[0069] In some embodiments of the present invention, the reaction temperature of the polymerization is 5-30°C, for example 10-20°C, or even 15°C or 20°C.

[0070] In some embodiments of the present invention, the reaction time for polymerization is 2-7 hours, for example 5-6 hours.

[0071] The present invention also provides a copolymer containing an oxazoline group prepared by the above method.

[0072] The present invention also provides the use of the oxazoline-containing copolymer for crosslinking a multifunctional polymer P, wherein the multifunctional polymer P contains at least two functional groups selected from carboxyl (-COOH), phosphate (-OP(OH)3), phenolic hydroxyl and aromatic thiol groups.

[0073] The present invention also provides the use of the oxazoline-containing copolymer as a crosslinking agent for polycarboxylic acid polymers.

[0074] The present invention also provides a method for crosslinking a multifunctional polymer P comprising at least two functional groups selected from carboxyl, phosphate, phenolic hydroxyl, and aromatic thiol groups, wherein at least one oxazoline-containing copolymer as described above is added to the multifunctional polymer P.

[0075] The present invention also provides a composition comprising:

[0076] i) at least one copolymer containing an oxazoline group as described above; ii) at least one multifunctional polymer P, which contains at least two functional groups selected from carboxyl, phosphate, phenolic hydroxyl and aromatic thiol groups.

[0077] In the context of this invention, the phenolic hydroxyl group refers to an hydroxyl group (-OH) that is directly bonded to an aromatic ring, particularly a benzene ring.

[0078] In the context of this invention, the aromatic thiol group refers to a thiol group (-SH) that is directly bonded to an aromatic ring, particularly a benzene ring.

[0079] In the context of this invention, the polycarboxylic acid polymer refers to a polymer containing at least two free carboxyl groups (-COOH).

[0080] The polycarboxylic acid polymer may be, for example, a polymer or copolymer comprising (meth)acrylic acid and optionally one or more other monoolefinically unsaturated monomers. In particular, the polycarboxylic acid polymer may be a copolymer of poly(meth)acrylic acid and / or (meth)acrylic acid and at least one other monomer selected from: (meth)acrylic acid C 1-20 -alkyl esters, especially (meth)acrylic acid C 1-12 -alkyl ester; C 8-20 -Vinyl aromatic compounds, especially C 8-10 - Vinyl aromatic compounds: unsaturated nitriles, such as (meth)acrylonitrile; unsaturated amides, such as (meth)acrylamide, N-methyl (meth)acrylamide, N,N'-dimethyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-cyclohexyl (meth)acrylamide, N-benzyl (meth)acrylamide; vinyl esters, such as vinyl formate, vinyl acetate, vinyl propionate; vinyl ethers, such as methyl vinyl ether, ethyl vinyl ether, hydroxyvinyl ethyl ether, hydroxyvinyl propyl ether, methyl vinyl butyl ether; and N-vinyl derivatives, such as N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam.

[0081] The present invention also provides the use of the composition as an adhesive in the production of adhesives, sealants, synthetic resin primers, paper coating slurries, nonwoven fabrics, flexible roofing coverings and paints, as well as in mineral sands; as a component in the production of textile or leather auxiliaries and impact modifiers; or for use in modifying mineral adhesives and plastics.

[0082] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0083] The reagents and raw materials used in this invention are all commercially available.

[0084] The positive and progressive effects of this invention are as follows: (1) This invention significantly reduces the activation energy for free radical generation by employing a redox system. The use of a redox system can increase the polymerization rate, thereby increasing production capacity and lowering the reaction temperature, thus improving polymer performance. It features mild reaction conditions, low energy consumption, fast reaction rate, and superior performance.

[0085] (2) Using the oxazoline-containing copolymer in this invention as a crosslinking agent can effectively improve the hydrolysis resistance and thermal stability of polymers containing carboxyl, acid anhydride, epoxy, phenol, mercapto, halogen and other groups; it has excellent adhesion and high viscosity. Detailed Implementation

[0086] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0087] The following abbreviations are used in the following examples and comparative examples: AA: Acrylic acid; VOXA: 2-vinyl-2-oxazoline; IPOX: 2-Isopropenyl-2-oxazoline; MMA: Methyl methacrylate; BA: n-Butyl acrylate; h: hour.

[0088] Example 1

[0089] (1) First, evacuate the reactor using a vacuum pump, then introduce nitrogen gas, repeating this process three times. After the air inside the reactor is completely removed, add 200 parts by mass of deionized water and 6 parts by mass of oxidizing / reducing agent C (oxidizing / reducing agent C is also called initiator) (molar ratio n 过硫酸钾 :n 亚硫酸氢钠 Add the mixture (1:1 ratio) to the reactor and stir until dissolved.

[0090] (2) Maintain the system temperature at 15℃, and add 70 parts by mass of monomer A: 2-isopropenyl-2-oxazoline (IPOX), 30 parts by mass of mixed monomer B (30 parts by mass of methyl methacrylate (MMA)) and 10 parts by mass of acrylic acid (adjusted to pH 9 using pH buffer ethylenediamine) into the reactor by dropping. Adjust the pH of monomer A and monomer B to 7-10 before dropping, and control the dropping time to be completed in about 3 hours.

[0091] (3) After monomers A and B and acrylic acid have been added dropwise, maintain the reaction temperature at 15°C and continue the reaction at a constant temperature for 5 hours. After the reaction time is over, remove the sample and filter it to obtain the filtrate, which is the aqueous crosslinking agent A containing oxazoline.

[0092] Example 2

[0093] (1) First, evacuate the reactor using a vacuum pump, then introduce nitrogen gas, repeating this process three times. After the air inside the reactor is completely removed, add 200 parts by mass of deionized water and 7 parts by mass of oxidizing / reducing agent C (molar ratio n).异丙苯过氧化氢 :n 硫酸亚铁 Add the mixture (1:0.9) to the reactor and stir until dissolved.

[0094] (2) Maintain the system temperature at 20℃, add 70 parts by mass of monomer A: 2-isopropenyl-2-oxazoline, 30 parts by mass of mixed monomer B (30 parts by mass of methyl methacrylate) and 10 parts by mass of acrylic acid (adjust the pH to 9 using pH buffer ethylenediamine). Before adding monomer A and monomer B, adjust the pH to 7-10. Add them to the reactor by dropping them, and control the dropping time to be about 3 hours to complete the dropping.

[0095] (3) After monomers A and B and acrylic acid have been added dropwise, maintain the reaction temperature at 20°C and continue the reaction at a constant temperature for 5 hours. After the reaction time is over, remove the sample and filter it to obtain the filtrate, which is the aqueous crosslinking agent B containing oxazoline.

[0096] Example 3

[0097] (1) First, evacuate the reactor using a vacuum pump, then introduce nitrogen gas, repeating this process three times. After the air inside the reactor is completely removed, add 200 parts by mass of deionized water and 6 parts by mass of oxidizing-reducing agent C (molar ratio n). 过硫酸钾 :n 亚硫酸氢钠 Add the mixture (1:0.9) to the reactor and stir until dissolved.

[0098] (2) Maintain the system temperature at 15℃, and add 70 parts by mass of monomer A: 2-isopropenyl-2-oxazoline and 30 parts by mass of mixed monomer B: 15 parts by mass of methyl methacrylate (MMA) + 15 parts by mass of n-butyl acrylate (BA) and 10 parts by mass of acrylic acid (adjusted to pH 9 using pH buffer ethylenediamine) in the reactor dropwise. Adjust the pH of monomer A and monomer B to 7-10 before dropwise addition, and control the dropwise addition time to be completed in about 3 hours.

[0099] (3) After monomers A and B and acrylic acid have been added dropwise, maintain the reaction temperature at 15°C and continue the reaction at a constant temperature for 6 hours. After the reaction time is over, remove the sample and filter it to obtain the filtrate, which is the aqueous crosslinking agent C containing oxazoline.

[0100] Example 4

[0101] (1) First, evacuate the reactor using a vacuum pump, then introduce nitrogen gas, repeating this process three times. After the air inside the reactor is completely removed, add 400 parts by mass of deionized water and 9 parts by mass of oxidizing-reducing agent C (molar ratio n). 过硫酸钾 :n 亚硫酸氢钠 Add the mixture (1:1 ratio) to the reactor and stir until dissolved.

[0102] (2) Maintain the system temperature at 20℃, and add 80 parts by mass of monomer A: 2-vinyl-2-oxazoline (VOXA), 30 parts by mass of mixed monomer B (30 parts by mass of n-butyl acrylate) and 10 parts by mass of acrylic acid (adjusted to pH 9 using pH buffer ethylenediamine) into the reactor by dropping. Adjust the pH of monomer A and monomer B to 7-10 before dropping, and control the dropping time to be completed in about 3 hours.

[0103] (3) After monomers A and B and acrylic acid have been added dropwise, maintain the reaction temperature at 20°C and continue the reaction at a constant temperature for 6 hours. After the reaction time is over, remove the sample and filter it to obtain the filtrate, which is the aqueous crosslinking agent D containing oxazoline.

[0104] Comparative Example 1

[0105] The only difference from Example 1 is that sodium bisulfite was not added to the initiator. An oxazoline-containing aqueous crosslinking agent E was obtained.

[0106] Comparative Example 2

[0107] The only difference from Example 1 is that the initiator was not added slowly dropwise, but directly into the reactor. This yielded an oxazoline-containing aqueous crosslinking agent F.

[0108] Comparative Example 3

[0109] The only difference from Example 1 is that the molar ratio of potassium persulfate to sodium bisulfite added to the initiator is 1:0.5. This yields an oxazoline-containing aqueous crosslinking agent G.

[0110] Comparative Example 4

[0111] The only difference from Example 1 is that the molar ratio of potassium persulfate to sodium bisulfite added to the initiator is 1:1.5. This yields an oxazoline-containing aqueous crosslinking agent H.

[0112] Comparative Example 5

[0113] The only difference from Example 1 is that 10 parts by mass of acrylic acid were not added to the monomer. This yielded an oxazoline-containing aqueous crosslinking agent I.

[0114] Comparative Example 6

[0115] The only difference from Example 1 is that the 10 parts by mass of acrylic acid added to the mixed monomers were not adjusted to pH >7 using the pH buffer ethylenediamine. This yielded an oxazoline-containing aqueous crosslinking agent J.

[0116] Comparative Example 7

[0117] The only difference from Example 1 is that the system temperature and reaction temperature were set to 50°C during the dropwise addition. This yielded an oxazoline-containing aqueous crosslinking agent K.

[0118] Comparative Example 8

[0119] The only difference from Example 1 is that the system temperature and reaction temperature were set to 0°C during the dropwise addition. An oxazoline-containing aqueous crosslinking agent L was obtained.

[0120] The conditions and parameters for preparing crosslinking agents A, B, C, D, E, F, G, H, I, J, K, and L in the above embodiments and comparative examples are summarized in Table 1 below.

[0121] Table 1. Preparation of aqueous crosslinking agents containing oxazoline-based agents

[0122] Example 1

[0123] Conversion rate [%] = (Weight of dried membrane - Weight of initiator) / Theoretical solid content of sample 100%. Among them: the drying method of the membrane is: baking at 100℃ for 4 hours, until the weight remains unchanged after baking for another 30 minutes; the theoretical solid content of the sample refers to the theoretical weight of the crosslinking agent generated.

[0124] pH: The filtrate containing the oxazoline-based aqueous crosslinking agent from each example and comparative example was tested using a Mettler Toledo Multi-Parameter Tester S400-B.

[0125] Viscosity: The filtrate containing the oxazoline-based aqueous crosslinking agent from each example and comparative example was measured at 25°C using a Brookfield DVS+ rotational viscometer.

[0126] Film-forming properties: Take a certain amount of sample into a sample dish, bake it in an oven at 100℃ for 4 hours, tilt the sample dish at an angle of 60-90 degrees and check whether liquid flows down. Liquid flowing down indicates poor film-forming properties.

[0127] Table 2 Properties of Aqueous Crosslinking Agents Containing Oxazoline Groups

[0128] In Table 2 above, "sample condition" refers to the sample at room temperature (25℃). + The gel is in a state of 5℃; it is a jelly-like gel with poor fluidity.

[0129] As can be seen from Table 2 above: (1) In Examples 1-4, the final monomer conversion rate can reach 97% or above. Even under low temperature conditions, a polymer with high conversion rate can still be obtained. The pH is close to neutral or weakly alkaline, and the viscosity is significantly improved. When acrylic acid is added after being neutralized by pH buffer, carboxyl groups are introduced. However, at this time, the carboxyl groups are neutralized by alkali, pH>7, and protonated H (-COOH) is not generated. Therefore, it will not react with oxazoline at this time.

[0130] (2) As can be seen from Examples 1-4 and Comparative Examples 1, 3, 4 and 8: Comparative Examples 1, 3 and 4 have low viscosity and poor film-forming properties, indicating that the amount of potassium persulfate initiator or reducing initiator alone is insufficient. At low temperatures, the low activity of the initiator leads to a lack of free radicals in the polymerization reaction, resulting in low reaction conversion and poor film formation. Secondly, in Comparative Example 4, the ratio of sodium bisulfite reducing agent exceeds 1. Excessive sodium bisulfite reacts again with the newly generated free radicals, resulting in insufficient free radicals. Therefore, the reaction conversion is low, the film formation is poor, and the viscosity is low. Similarly, the reaction temperature of Comparative Example 8 is too low, the initiator activation is low, and the number of free radicals generated is small. Therefore, the reaction conversion is low, the film formation is poor, and the viscosity is low.

[0131] (3) As can be seen from Examples 1-4 and Comparative Example 2, when the monomer is fed in one go, the initial initiation speed is too fast due to the excessive amount of initiator produced in the early stage, which leads to uncontrollable local polymerization reaction and easy formation of large molecular gel substances. Therefore, the viscosity is extremely high, the flow phase is different, and it is similar to jelly. The remaining monomer cannot be initiated to polymerize.

[0132] (4) As can be seen from Examples 1-4 and Comparative Example 5: Comparative Example 5 did not add acrylic acid after pH buffering. Although it can form a sheet film and has a high conversion rate, it did not introduce carboxyl groups, resulting in a lower viscosity.

[0133] (5) As can be seen from Examples 1-4 and Comparative Example 6: Although acrylic acid was added to Comparative Example 6, the acrylic acid monomer was added directly without being neutralized by a pH buffer. The carboxyl group was not deprotonated, which caused the carboxyl group to react directly with the oxazoline group, consuming a large portion of the raw material monomer (forming a new non-volatile small molecule substance). Therefore, the conversion rate of the dried sample was high, but the substance failed to form a film after drying, indicating that a side reaction occurred.

[0134] (6) In Comparative Example 7, due to the high temperature, the alkaline substances evaporated during the reaction, causing the originally neutralized carboxyl groups to reform and react with the oxazoline groups, consuming the raw material monomers, resulting in poor film formation and low viscosity.

[0135] Example 2

[0136] 10g of polyacrylic acid (Titan Technology Exploration Platform, MW: 55000) was mixed evenly with 2g of oxazoline-based aqueous crosslinking agent filtrate prepared in Examples 1-4 above. The mixture was poured into a smooth grooved sample stage and placed in an oven at a constant temperature of 60℃ for 24 hours to prepare a dried film. The swelling degree, hydrolysis resistance, and acid and alkali resistance of the crosslinked copolymer were tested.

[0137] The results are summarized in Table 3 below.

[0138] (1) Swelling test method: The cross-linked dried membrane was placed in tetrahydrofuran (THF) and vibrated in the THF for 2 hours at 100°C. Then it was removed from the THF, gently patted dry and weighed. A low swelling degree means that the membrane is highly cross-linked.

[0139] Swelling percentage [%] = Weight of swollen film / Weight of dried film 100.

[0140] (2) Hydrolysis resistance: The dried film obtained by cross-linking and curing is placed in water at 100°C and vibrated in an experimental vibrator for 1 week to check whether the dried film dissolves.

[0141] (3) Solvent resistance: Wipe the surface of the dried film obtained by cross-linking and curing at least 25 times with degreased cotton soaked in solvent (xylene) to check the degree of damage to the film surface.

[0142] Table 3. Results of tests on the swelling degree, hydrolysis resistance, and solvent resistance of the crosslinked copolymers.

[0143] As can be seen from the test results of swelling degree, hydrolysis resistance and solvent resistance of crosslinked copolymers in Table 3 above, the crosslinking agents prepared by the method of the present invention in Examples 1-4 (corresponding to crosslinking agent AD) have low swelling degree with carboxyl polymers, indicating high crosslinking degree. That is, the oxazoline group reacts highly with active groups (carboxyl, acid anhydride, epoxy, phenolic group, etc.), which can effectively improve the hydrolysis resistance and solvent resistance of carboxyl polymers.

[0144] Example 3

[0145] (1) Take a certain amount of polyacrylic acid (Titan Technology Exploration Platform, MW: 55000) and mix it evenly with the crosslinking agents A, B, C, D, E, F, G, H, I, J, K and L prepared in the above examples and comparative examples (the molar ratio of polyacrylic acid and crosslinking agent is 1:1, and the molar ratio can be determined by titration). Coat it on the release paper so that the thickness after drying is 20 μm. After drying at 100°C for 5 min, it is bonded to a 50 μm PET film substrate to obtain a bonded adhesive film, which is tested by a peel force tester.

[0146] Peel strength: determined according to GB / T 7122-1996.

[0147] (2) Take a certain amount of polyacrylic acid (Titan Technology Exploration Platform, MW: 55000) and mix it evenly with the crosslinking agents A, B, C, D, E, F, G, H, I, J, K and L prepared in the above examples and comparative examples (the molar ratio of polyacrylic acid and crosslinking agent is 1:1, and the molar ratio can be determined by titration). Coat it on the release paper so that the thickness after drying is 20 μm. Dry it at 100°C for 5 min to obtain a dried film.

[0148] Tensile strength: determined according to GB / T 1040.

[0149] Overall evaluation: 1. Peel strength ≥ 13 MPa, tensile strength ≥ 18 MPa; 2. Peel strength: 10-13 MPa, tensile strength: 10-18 MPa; 3: Peel strength < 10 MPa, tensile strength < 10 MPa.

[0150] Table 4

[0151] As can be seen from Table 4 above, the crosslinking agents prepared by the method in Examples 1-4 (corresponding to crosslinking agent AD) can effectively improve the peel resistance of carboxyl-containing polymers, have good film adhesion, and also improve the tensile properties.

Claims

1. A method for preparing a copolymer containing an oxazoline group, characterized in that, It includes the following steps: The following monomers are polymerized in the presence of a solvent and a redox agent C: a) at least one olefinic unsaturated monomer A, which contains at least one 2-substituted oxazoline group; b) At least one of (meth)acrylic acid C 1-20- Alkyl esters or C 8-20- Monomer B of vinyl aromatic compounds; c) Acrylates; in: (1) In the redox agent C, the molar ratio of oxidant to reductant is 1:(0.8-1.2); (2) Monomer A: 40-90 parts by weight, Monomer B: 10-40 parts by weight, Acrylate: 5-30 parts by weight, Redox Agent C: 1-10 parts; (3) The monomer A, the monomer B and the acrylate are added dropwise or mixed and added dropwise to the mixture of the solvent and the redox agent C; (4) The reaction temperature for polymerization is 5-40℃.

2. The method for preparing the oxazoline-containing copolymer as described in claim 1, characterized in that, In the redox agent C, the oxidant is potassium persulfate and cumene hydrogen peroxide; And / or, in the redox agent C, the reducing agent is selected from at least one of the following combinations: sodium thiosulfate, sodium bisulfite, sodium sulfite, ferrous sulfate, sodium metabisulfite, sodium formaldehyde sulfoxylate, ascorbic acid, ethylenediamine, sodium ethylenediaminetetraacetate, glycine, N-isopropylhydroxylamine. And / or, in the redox agent C, the molar ratio of oxidant to reductant is 1:(0.9-1.0).

3. The method for preparing the oxazoline-containing copolymer as described in claim 2, characterized in that, The reducing agent is selected from at least one of sodium bisulfite, ferrous sulfate, and N-isopropylhydroxylamine.

4. The method for preparing the oxazoline-containing copolymer as described in claim 2, characterized in that, The molar ratio of the oxidant to the reducing agent is 1:0.9 or 1:1.

0.

5. The method for preparing the oxazoline-containing copolymer as described in claim 1 or 2, characterized in that, The polymerization reaction temperature is 5-30℃; And / or, the reaction time for the polymerization is 2-7 hours.

6. The method for preparing the oxazoline-containing copolymer as described in claim 5, characterized in that, The polymerization reaction temperature is 10-20℃.

7. The method for preparing the oxazoline-containing copolymer as described in claim 5, characterized in that, The polymerization reaction time is 5-6 hours.

8. A copolymer containing an oxazoline group, characterized in that, The oxazoline-containing copolymer is prepared by any one of the preparation methods according to claims 1-7.

9. The oxazoline-containing copolymer as described in claim 8, characterized in that, The monomer A is a compound as shown in formula (I). (I), The group has the following meanings: R1 is a C that contains at least one olefinic unsaturated group. 2-20- alkenyl; R2, R3, R4, and R5 are independently selected from H, halogens, and C. 1-20 -alkyl, C 2-20 -Alkenyl, C 6-20 -Aryl, C 7-32 -Arylalkyl, C 1-20 -Hydroxyalkyl, C 1-20 -aminoalkyl and C 1-20 - Haloalkyl; And / or, the monomer B is selected from at least one of the following monomers: (meth)acrylic acid C 1-20 -Alkyl ester.

10. The oxazoline-containing copolymer as described in claim 9, characterized in that, R2, R3, R4, and R5 are independently selected from H, halogens, and C1-20 -alkyl.

11. The oxazoline-containing copolymer as described in claim 9, characterized in that, The monomer B is selected from (meth)acrylic acid C. 1-12 - At least one of alkyl esters.

12. The oxazoline-containing copolymer as described in claim 11, characterized in that, The monomer B is selected from (meth)acrylic acid C. 1-8 - At least one of alkyl esters.

13. The oxazoline-containing copolymer as described in claim 9, characterized in that, The monomer A is at least one monomer selected from the following: 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-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 p-styryl-2-oxazoline; And / or, said monomer B is at least one monomer selected from the following: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, sec-butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, styrene, α-methylstyrene and vinyltoluene.

14. The oxazoline-containing copolymer as described in claim 13, characterized in that, The monomer A is selected from at least one of 2-vinyl-2-oxazoline and 2-isopropenyl-2-oxazoline.

15. The oxazoline-containing copolymer as described in claim 13, characterized in that, The monomer B is selected from one or more of methyl acrylate, methyl methacrylate, n-butyl acrylate, and butyl methacrylate.

16. The copolymer containing an oxazoline group as described in any one of claims 8-15, characterized in that, The monomer A is 50-80 parts by mass; And / or, the monomer A is present in an amount of 50.0 to 98.0% by weight, based on the total amount of monomers in the oxazoline-containing copolymer; And / or, the monomer B is 15-40 parts by mass; And / or, the monomer B is present in an amount of 1.0 to 45.0% by weight, based on the total amount of monomers in the oxazoline-containing copolymer; And / or, the acrylate is present in 5-15 parts by mass; And / or, the acrylate is present in an amount of 0.1 to 25.0% by weight, based on the total amount of monomers in the oxazoline-containing copolymer.

17. The oxazoline-containing copolymer of claim 16, characterized in that, The monomer A is present in an amount of 50.5 to 85.0% by weight, based on the total amount of monomers in the oxazoline-containing copolymer.

18. The oxazoline-containing copolymer as described in claim 16, characterized in that, The monomer B is present in an amount of 10.0 to 39.5% by weight, based on the total amount of monomers in the oxazoline-containing copolymer.

19. The oxazoline-containing copolymer as described in claim 16, characterized in that, The acrylate is present in an amount of 1.0 to 20.0% by weight, based on the total amount of monomers in the oxazoline-containing copolymer.

20. The oxazoline-containing copolymer of claim 17, characterized in that, The monomer A is present in an amount of 55.0 to 72.0% by weight, based on the total amount of monomers in the oxazoline-containing copolymer.

21. The oxazoline-containing copolymer as described in claim 18, characterized in that, The monomer B is present in an amount of 15.0 to 35.0% by weight, based on the total amount of monomers in the oxazoline-containing copolymer.

22. The oxazoline-containing copolymer as described in claim 19, characterized in that, The acrylate is present in an amount of 5.0 to 19.5% by weight, based on the total amount of monomers in the oxazoline-containing copolymer.

23. Use of the oxazoline-containing copolymer as described in any one of claims 8-22 for crosslinking a multifunctional polymer P, said multifunctional polymer P comprising at least two functional groups selected from carboxyl, phosphate, phenolic hydroxyl, and aromatic thiol groups.

24. A method for crosslinking a multifunctional polymer P comprising at least two functional groups selected from carboxyl, phosphate, phenolic hydroxyl, and aromatic thiol groups, wherein at least one oxazoline-containing copolymer as described in any one of claims 8-22 is added to the multifunctional polymer P.

25. A composition, characterized in that, It contains i) at least one copolymer containing an oxazoline group as described in any one of claims 8-22; ii) at least one multifunctional polymer P, which contains at least two functional groups selected from carboxyl, phosphate, phenolic hydroxyl and aromatic thiol groups.

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