Cross-linked acrylate copolymers, processes for their preparation and use

Abstract

The application relates to the field of rubber materials and discloses a crosslinked acrylate copolymer and a preparation method and application thereof, the copolymer comprises structural unit A from acrylate, structural unit B from ethylene, structural unit C from furan-substituted acrylate and structural unit D from a coupling agent, the content of the structural unit A is 10-80 wt%, the content of the structural unit B is 15-82 wt%, the content of the structural unit C is 3-10 wt%, and the content of the structural unit D is 1-6 wt% based on the total amount of the copolymer. The acrylate copolymer is a material with a reversible crosslinked network structure, the coupling agent is added to form a network structure in the prepared acrylate copolymer, and the crosslinking of rubber is strengthened; the acrylate copolymer is heated to above 120 DEG C by utilizing the thermal reversibility of D-A reaction, the crosslinking of rubber is broken, and the rubber has heat processability; the rubber can be crosslinked again to form a network structure when the rubber is cooled to below 80 DEG C, and the mechanical properties of the rubber are enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rubber materials, in particular to a cross-linked acrylate copolymer and a preparation method and application thereof. BACKGROUND

[0002] Acrylate rubber is widely used in the automotive industry due to its high-temperature oil resistance and high-temperature anti-aging performance. The introduction of ethylene into the acrylate polymer can improve the cold resistance of the material and further broaden the application range of acrylate rubber. However, uncross-linked acrylate rubber does not have the elasticity, resilience, strength and dimensional stability required in the rubber application process, so it must be cross-linked and modified.

[0003] Vulcanization cross-linking is the main cross-linking technology for polymer materials at present. The cross-linking covalent bond formed by vulcanization cross-linking is irreversible, making the cross-linked polymer unable to be processed again. Therefore, while giving the material excellent performance, it also brings the problem of recycling and reusing of the polymer material. People usually use a combination of heat treatment and mechanical treatment to break the vulcanization cross-linking bond, but this process will cause the main chain of the polymer to break, and only 25% of the products obtained after devulcanization can be reused.

[0004] In recent years, with the enhancement of human environmental protection consciousness, many countries and regions have developed the recycling and recycling of rubber into an entity industry. The recycled waste can not only be converted into new energy or other materials, but also can bring considerable economic benefits. Realizing the green recycling of cross-linked rubber and avoiding material damage caused by the treatment process as much as possible so that it can be recycled is the common goal pursued by researchers and the industry.

[0005] If the construction of reversible cross-linking structure can be realized during the synthesis of acrylate rubber, and cross-linked acrylate rubber with repeatable processability can be directly prepared in the polymerization kettle, not only the innovation of synthesis method can be realized, but also the innovation of product performance can be realized, which has important environmental protection significance. SUMMARY

[0006] The purpose of the present application is to overcome the problem of low recycling efficiency of existing acrylate rubber in the prior art, and to provide a cross-linked acrylate copolymer and a preparation method and application thereof. The cross-linked acrylate copolymer can be dissociated by reverse reaction at high temperature, so that the cross-linked acrylate copolymer is de-cross-linked, giving the cross-linked polymer repeatable processability, thereby facilitating recycling and reuse.

[0007] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a cross-linked acrylate copolymer, wherein the copolymer comprises structural units A from acrylate, structural units B from ethylene, structural units C from furan-substituted acrylate, and structural units D from a coupling agent.

[0008] The content of the structural unit A is 10-80 wt%, the content of the structural unit B is 15-82 wt%, the content of the structural unit C is 3-10 wt%, and the content of the structural unit D is 1-6 wt%, based on the total amount of the copolymer.

[0009] The second aspect of the present application provides a preparation method of a crosslinked acrylate copolymer, wherein, in the presence of an initiator, acrylate, furan-substituted acrylate and ethylene are subjected to a polymerization reaction, after the reaction is completed, ethylene is vented, a coupling agent is added to perform a crosslinking reaction, and a crosslinked acrylate copolymer is obtained.

[0010] The third aspect of the present application provides an application of a crosslinked acrylate copolymer as a reinforcing acrylate rubber material.

[0011] Dynamic covalent chemistry provides an effective method for preparing polymers with reversible structural changes. Dynamic covalent reaction is a reversible chemical process between molecules through the formation and rupture of covalent bonds. Commonly used dynamic covalent reactions in polymer synthesis include Diels-Alder (D-A) reaction, disulfide bond, imine bond, acylhydrazone bond, reversible borate esterization reaction, and reversible radical reaction. Under specific stimuli (heat, pH, light, oxidation-reduction reagent, etc.), reversible structural changes can occur between reactants and products. As an effective cycloaddition reaction, D-A reaction (Diels-Alder reaction) forms a stable six-membered ring compound through [4+2] cycloaddition between electron-rich diene and electron-deficient dienophile. The reaction does not require a catalyst and is easy to implement.

[0012] The reaction process of the present application is specifically shown in Figure 3 and 4 First, acrylate, ethylene and furan-substituted acrylate are subjected to a polymerization reaction to obtain ethylene-acrylate rubber with furan groups on the side groups, as shown in Figure 3 The ethylene-acrylate rubber with furan groups on the side groups is subjected to a crosslinking reaction with a coupling agent. The maleimide groups at both ends of the coupling agent undergo D-A reaction with the furan groups on the side groups of the ethylene-acrylate rubber, thereby forming a crosslinking network structure between different ethylene-acrylate rubber molecular chains, obtaining a crosslinked acrylate copolymer, and the mechanism is shown in Figure 4 The copolymer obtained has a crosslinking between the main chains through a bridge chain, which contains furan groups from furan-substituted acrylate and maleimide groups from the coupling agent.

[0013] The crosslinked acrylate copolymer obtained is measured for 1 H-NMR spectrum, and the results are shown in Figure 1As shown, the chemical shift at 5.1 ppm in the figure is the characteristic peak of hydrogen atom from -OCH2- in furan-substituted furfuryl acrylate connected with furan group, the characteristic peaks of hydrogen atom from furan ring in furan-substituted furfuryl acrylate are at 6.4 ppm and 7.5 ppm respectively, which proves that furan group is successfully introduced into the side group of ethylene-acrylate rubber.

[0014] The obtained crosslinked acrylate copolymer is observed by infrared spectrum, and it is found that the in-plane bending vibration of ether bond C-O-C in the six-membered ring generated by D-A reaction appears at 1177 cm -1 nearby. The process of D-A bond generation and breakage in the crosslinked acrylate copolymer with temperature change is observed by variable temperature FTIR test. The infrared data scanning of the crosslinked sample is carried out at 140℃, the D-A bond characteristic peak intensity at 1177 cm -1 decreases with the increase of temperature, and the reverse D-A reaction occurs; the uncrosslinked sample at 140℃ is cooled to 40℃ again, and the D-A bond characteristic intensity at 1177 cm -1 increases again, which indicates that D-A reaction occurs. This shows that the reversible process of D-A reaction dissociation by heating and association by cooling is successfully realized in the prepared acrylate rubber of the application.

[0015] The acrylate copolymer of the application is a material with reversible crosslinked network structure. The network structure is formed in the prepared acrylate copolymer by adding coupling agent, so as to realize the crosslinking and strengthening of rubber; the heat reversibility of D-A reaction is utilized, and when the copolymer is heated to above 120℃, the uncrosslinking of rubber can be realized, so that the rubber has heat processability; and when it is cooled to below 80℃, the network structure can be generated again, so as to enhance the mechanical properties of rubber.

[0016] The prepared acrylate copolymer is applied as reinforced acrylate rubber, and has excellent properties such as high strength, excellent deformation resistance, good elasticity and repeatable processing. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The H-NMR spectrum of the crosslinked acrylate copolymer obtained in Example 2 and Comparative Example 1 of the application is shown in Figure 2. 1 The infrared spectrum of the crosslinked acrylate copolymer obtained in Example 2 of the application is shown in Figure 3.

[0018] Figure 2 The infrared spectrum of the crosslinked acrylate copolymer obtained in Example 2 of the application is shown in Figure 3.

[0019] Figure 3 The reaction mechanism diagram of the polymerization reaction in the application is shown in Figure 4.

[0020] Figure 4 The reaction mechanism diagram of the crosslinking reaction in the application is shown in Figure 5. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the properties. The endpoints of the ranges and any numerical values are to be understood as approximations.

[0022] The first aspect of the present application provides a crosslinked acrylate copolymer, wherein the copolymer comprises structural units A from acrylate, structural units B from ethylene, structural units C from furan-substituted acrylate, and structural units D from coupling agent.

[0023] The content of the structural units A is 10-80wt%, the content of the structural units B is 15-82wt%, the content of the structural units C is 3-10wt%, and the content of the structural units D is 1-6wt%, based on the total amount of the copolymer.

[0024] In the present application, the carbon-carbon double bonds contained in acrylate, ethylene and furan-substituted acrylate form multiple copolymer chains through polyaddition reaction, and the coupling agent forms six-membered ring structure containing bridging ether bond through D-A reaction between the double-end group and the furan group contained in the side group of the structural units C in different copolymer chains, realizing the crosslinking connection between different copolymer chains, i.e. the coupling agent provides the connection structure or connecting group between different copolymer chains.

[0025] In some embodiments of the present application, preferably, the gel content of the copolymer is not less than 80%, and the characteristic peak of the ether bond C-O-C appears in the infrared spectrum of the copolymer at 1177cm -1 The D-A reaction forms a six-membered ring, and the appearance of the characteristic peak of the C-O-C bond in the six-membered ring indicates that the D-A reaction is successfully introduced into the obtained copolymer, so that it has the properties of de-crosslinking at high temperature and re-polymerization at low temperature.

[0026] The copolymer has a gel content of not less than 80 wt%. The presence and efficiency of cross-linking in the polymer can be determined by measuring the gel content. The acrylate monomer is selected from at least one of methyl acrylate, ethyl acrylate, and butyl acrylate. Based on the total amount of the copolymer, the content of structural unit A can be any value within the range of any two numbers from 10 wt%, 15 wt%, 25 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, to 80 wt%; the content of structural unit B can be 15 wt%, 20 wt%, 30 wt%, to 80 wt%. The content of structural unit C can be any value within the range of any two numbers formed by 40wt%, 50wt%, 60wt%, 70wt%, 75wt%, and 82wt%; the content of structural unit D can be any value within the range of any two numbers formed by 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, and 10wt%; the content of structural unit D can be any value within the range of any two numbers formed by 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, and 6wt%.

[0027] In some embodiments of the present invention, preferably, the elongation at break of the copolymer is not less than 180%. Elongation at break reflects the elasticity and toughness of the polymer, and the elongation at break of the polymer is not less than 180%, preferably not less than 240%.

[0028] In some embodiments of the present invention, preferably, the furan-substituted acrylate is selected from... and / or Preferred Furan-substituted acrylates without methyl groups can produce polymers with lower glass transition temperatures, thus improving their low-temperature performance.

[0029] In some embodiments of the present invention, preferably, the coupling agent is selected from... and / or Where R is an alkyl group with 1 to 10 carbons. R can be an alkylene group with 1, 5, or 10 carbons.

[0030] A second aspect of the present invention provides a method for preparing a crosslinked acrylate copolymer, wherein, in the presence of an initiator, acrylate, furan-substituted acrylate and ethylene are polymerized, ethylene is vented after the reaction is completed, and a coupling agent is added to carry out a crosslinking reaction to obtain a crosslinked acrylate copolymer.

[0031] In this invention, acrylates, furan-substituted acrylates, and ethylene are used as monomers, which undergo addition polymerization through their respective carbon-carbon double bonds to form polymer chains. Then, a coupling agent containing terminal maleimide groups reacts with the furan groups introduced into the polymer chains via a DA reaction, thereby establishing a linking structure between the different polymer chains and forming a cross-linked acrylate copolymer. A schematic diagram of the above reaction mechanism is shown below. Figure 3 and 4 As shown in the example.

[0032] In some embodiments of the present invention, preferably, the mass ratio of the furan-substituted acrylate to the acrylate is 1:9 to 3:8. Specifically, the mass ratio of the furan-substituted acrylate to the acrylate can be any value within the range of any two numbers chosen from 1:9, 3:17, 4:17, and 3:8.

[0033] In some embodiments of the present invention, preferably, the pressure of the ethylene monomer is 1-100 MPa.

[0034] The amounts of acrylate and ethylene affect the glass transition temperature and crosslinking efficiency of the polymer, with the crosslinking efficiency being reflected by the gel content. The molar ratio of furan-substituted acrylate to the acrylate can be any value within the range of any two numbers from 0.01:1, 0.05:1, 0.1:1, 0.3:1, and 0.5:1; the ethylene pressure can be any value within the range of any two numbers from 1 MPa, 10 MPa, 20 MPa, 30 MPa, 50 MPa, and 100 MPa.

[0035] In some embodiments of the present invention, preferably, the amount of the initiator is 0.01-1 wt% of the total mass of the acrylate and furan-substituted acrylate. The initiator can be one or more of thermal decomposition free radical initiators, organic peroxides, and azo initiators, preferably alkyl peroxides, hydroperoxides, acyl peroxides, and peroxycarbonates. Specifically, alkyl peroxides can be triethylaluminum, triethylboron, or triethyllead; hydroperoxides can be cumene hydroperoxide or tert-butyl hydroperoxide; acyl peroxides can be benzoyl peroxide or lauroyl peroxide; peroxycarbonates can be diisopropyl peroxide or dicyclohexyl peroxide; and azo initiators can be azobisisobutyronitrile or azobisisoheptanenitrile. The amount of the initiator is any value within the range of any two numbers from 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, and 1 wt% of the total mass of the acrylate and furan-substituted acrylate.

[0036] In some embodiments of the present invention, preferably, the polymerization reaction temperature is 0-100℃ and the time is 0.1-12h. Excessively high or low polymerization temperatures will result in a lower ethylene insertion rate and poorer polymer thermal properties; short reaction times will result in low polymer molecular weight and poor thermal properties, while long reaction times will result in excessively large molecular weight, which is detrimental to processing. The polymerization reaction temperature can be any value within the range of any two numbers from 0℃, 20℃, 50℃, 80℃, and 100℃.

[0037] In some embodiments of the present invention, preferably, a solvent is also included, wherein the acrylate, furan-substituted acrylate, and solvent are mixed before the polymerization reaction. The solvent is an alkane with 5 to 10 carbon atoms and / or an aromatic hydrocarbon with 6 to 10 carbon atoms, wherein the alkane with 5 to 10 carbon atoms is selected from at least one of n-pentane, n-hexane, cyclohexane, n-heptane, n-octane, and n-decane; and the aromatic hydrocarbon with 6 to 10 carbon atoms is selected from at least one of benzene, toluene, xylene, ethylbenzene, n-propylbenzene, and isopropylbenzene. The mass ratio of the total mass of the acrylate and furan-substituted acrylate to the mass of the solvent can be any value within the range of any two numbers from 1:100, 300:100, 500:100, 800:100, and 1000:100.

[0038] In some embodiments of the present invention, preferably, the mass ratio of the coupling agent to the furan-substituted acrylate is 0.1-0.5:1. The coupling agent and the furan-substituted acrylate together endow the polymer with reversible crosslinking functionality. The coupling agent can be added in two ways: ① directly into the reaction system; ② dispersing the coupling agent in an organic solvent before adding it to the reaction system. The organic solvent in method ② can be the same as or different from the solvent used in the polymerization reaction, and can be selected from at least one of n-pentane, n-hexane, cyclohexane, n-heptane, n-octane, and n-decane, or from at least one of benzene, toluene, xylene, ethylbenzene, n-propylbenzene, and isopropylbenzene.

[0039] In some embodiments of the present invention, preferably, the crosslinking reaction temperature is 40-80°C and the time is 0.1-12h. If the crosslinking reaction temperature is too low, the obtained polymer has a low molecular weight and poor mechanical properties; if the reaction temperature is too high, gelation is likely to occur. If the reaction time is too short, the polymer has a low molecular weight and poor mechanical properties; if the reaction time is too long, the molecular weight is too large, gelation is likely to occur, which is not conducive to processing. Therefore, the crosslinking reaction temperature can be any value within the range of any two numbers from 40°C, 60°C, and 80°C, and the crosslinking time can be any value within the range of any two numbers from 0.1h, 3h, 6h, 9h, and 12h.

[0040] A third aspect of this invention provides an application of a crosslinked acrylate copolymer as a reinforcing acrylate rubber material. The copolymer prepared according to this invention exhibits significantly increased tensile strength compared to uncrosslinked copolymers. While the tensile strength is comparable to that obtained using conventional vulcanization crosslinking, the copolymer of this invention possesses a greater elongation at break, meaning it exhibits superior elasticity and toughness.

[0041] According to a particularly preferred embodiment of the present invention, based on the total amount of the copolymer, the content of structural unit A is 10-60 wt%, the content of structural unit B is 30-82 wt%, the content of structural unit C is 6-8 wt%, and the content of structural unit D is 2-3 wt%.

[0042] The present invention will be described in detail below through examples. In the following examples, the gel content was determined by the DMF room temperature swelling method; the glass transition temperature was determined by the DSC method; and the tensile strength and elongation at break were measured according to GB / T 1040.1-2006.

[0043] Coupling agent D: N,N'-(4,4'-methylenediphenyl)bismaleimide, purchased from Anaiji Chemical, CAS No. 13676-54-5, structural formula:

[0044] Methyl acrylate was purchased from Alfa.

[0045] Ethyl acrylate was purchased from Alfa.

[0046] Butyl acrylate was purchased from Alfa.

[0047] Ethylene was purchased from commercially available products from Selgas.

[0048] Azobisisobutyronitrile was purchased from Aladdin Company.

[0049] Preparation Example 1

[0050] Synthesis of furfuryl acrylate (A):

[0051] 10.85 g of furfuryl alcohol and 16.58 g of triethylamine were poured into a flask containing 100 mL of dichloromethane and stirred in an ice-water bath for 10 min. Then, 10.14 g of acryloyl chloride was injected into a dropping funnel through a syringe that had been purged with nitrogen three times. The funnel was sealed and slowly dripped into the flask (approximately 30 min). After stirring continuously in an ice-water bath for 5 h, the product was filtered. The filtrate was extracted sequentially with saturated NaCl aqueous solution, saturated NaHCO3 aqueous solution, and saturated NaCl aqueous solution. The organic phase was collected, dried over anhydrous magnesium sulfate, and filtered. The filtrate was then distilled under reduced pressure to remove the solvent dichloromethane, yielding furfuryl acrylate A.

[0052] Preparation Example 2

[0053] Synthesis of furfuryl methacrylate (B):

[0054] 11.77 g of furfuryl alcohol and 18.24 g of triethylamine were poured into a flask containing 100 mL of dichloromethane and stirred in an ice-water bath for 10 min. Then, 18.72 g of methacryloyl chloride was injected into a dropping funnel through a syringe that had been purged with nitrogen three times. After sealing, the mixture was slowly added dropwise to the flask (approximately 30 min). The mixture was stirred continuously in an ice-water bath for 5 h. The product was then filtered, and the filtrate was extracted sequentially with saturated NaCl aqueous solution, saturated NaHCO3 aqueous solution, and saturated NaCl aqueous solution. The organic phase was collected, dried over anhydrous magnesium sulfate, and filtered. The filtrate was then distilled under reduced pressure to remove the solvent dichloromethane, yielding furfuryl methacrylate B.

[0055] Preparation Example 3

[0056] Synthesis of 1,6-dimaleimide hexane (C):

[0057] Furan-protected maleic anhydride (60.2 mmol) and triethylamine (7 mL) were dissolved in 60 mL of methanol. Then, a methanol solution of hexamethylenediamine (25.1 mmol) was added dropwise under an ice-water bath. The resulting mixture was then refluxed in an oil bath at 80 °C for 48 h under nitrogen atmosphere. After reflux, the solution was placed in a freezer at -20 °C, yielding pale yellow crystals. These crystals were dried under vacuum and then dissolved in 50 mL of toluene. The solution was then refluxed in an oil bath at 120 °C for 48 h under nitrogen atmosphere. After reflux, the solution was again placed in a freezer at -20 °C, yielding pale yellow crystals, which were then dried under vacuum to obtain coupling agent C.

[0058] Example 1

[0059] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 5g of furfuryl acrylate A, and 0.2g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 10MPa, and the reaction was carried out at 70℃ for 3 hours. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 2.5g of coupling agent C was added to the reactor. The reaction was carried out at 70℃ for 3 hours. The product was collected, washed, and dried to obtain 74g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0060] Example 2

[0061] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 40g of ethyl acrylate, 15g of furfuryl acrylate A, and 0.5g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 10MPa, and the reaction was carried out at 70℃ for 3 hours. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 4g of coupling agent C was added to the reactor. The reaction was carried out at 70℃ for 3 hours. The product was collected, washed, and dried to obtain 155g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0062] The copolymer was analyzed using a Varian DLG 400 nuclear magnetic resonance spectrometer with deuterated tetrachloroethane as solvent at 100°C. 1 H-NMR spectrum, such as Figure 1 As shown. The peaks with chemical shifts between 1.0 and 2.5 ppm are characteristic peaks of hydrogen atoms in the polymer backbone and hydrogen atoms from the -CH3 group in ethyl acrylate, while the peak at chemical shift 4.2 ppm is a characteristic peak of hydrogen atoms from the -OCH2- group in ethyl acrylate. Compared with the polymer without furfuryl acrylate (Comparative Example 1), it can be clearly seen that in the copolymer prepared in Example 2, the newly appearing chemical shift at 5.1 ppm is a characteristic peak of hydrogen atoms from the -OCH2- group in furfuryl acrylate A linked to the furan group, and the peaks at 6.4 ppm and 7.5 ppm are characteristic peaks of hydrogen atoms from the furan ring in furfuryl acrylate A, respectively, proving the successful introduction of furan groups onto the side groups of the ethylene-acrylate rubber.

[0063] The prepared polymer was further pressed into shape on a flat vulcanizer at 180°C, then cut into small pieces, and pressed into shape again on a flat vulcanizer at 180°C to obtain Example 2'. The properties of the polymer were tested as shown in Table 2.

[0064] The polymer obtained in Experiment 2' was further cut into small pieces and placed on a flat vulcanizing apparatus and pressed at 180°C to obtain Example 2". The test performance results are shown in Table 2.

[0065] Example 3

[0066] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 35g of butyl acrylate, 15g of furfuryl methacrylate B, and 0.2g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 10MPa, and the reaction was carried out at 70℃ for 3 hours. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 3.0g of coupling agent C was added to the reactor. The reaction was carried out at 70℃ for 3 hours. The product was collected, washed, and dried to obtain 140g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0067] Example 4

[0068] In a 2L reactor, 200mL of n-heptane, 45g of methyl acrylate, 40g of ethyl acrylate, 15g of furfuryl acrylate A, and 0.2g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 30MPa, and the reaction was carried out at 70℃ for 3h. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 4.0g of coupling agent C was added to the reactor. The reaction was carried out at 70℃ for 3h. The product was collected, washed, and dried to obtain 195g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0069] Example 5

[0070] In a 2L reactor, 200mL of n-heptane, 45g of methyl acrylate, 40g of ethyl acrylate, 15g of furfuryl acrylate A, and 0.2g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 30MPa, and the reaction was carried out at 70℃ for 3 hours. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 5g of coupling agent D was added to the reactor. The reaction was carried out at 70℃ for 3 hours. The product was collected, washed, and dried to obtain 196g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0071] Example 6

[0072] In a 2L reactor, 200mL of toluene, 40g of ethyl acrylate, 15g of furfuryl methacrylate B, and 0.2g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 20MPa, and the reaction was carried out at 70℃ for 3h. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 2g of coupling agent D was added to the reactor. The reaction was carried out at 70℃ for 5h. The product was collected, washed, and dried to obtain 122g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0073] Example 7

[0074] In a 2L reactor, 200mL of n-heptane, 45g of methyl acrylate, 40g of ethyl acrylate, 20g of furfuryl acrylate A, and 0.5g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 10MPa, and the reaction was carried out at 70℃ for 4 hours. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 8.0g of coupling agent C was added to the reactor. The reaction was carried out at 70℃ for 4 hours. The product was collected, washed, and dried to obtain 170g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0075] Example 8

[0076] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 40g of ethyl acrylate, 10g of furfuryl acrylate A, 5g of furfuryl methacrylate B, and 0.5g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 10MPa, and the reaction was carried out at 70℃ for 4 hours. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 2.0g of coupling agent C and 2.0g of coupling agent D was added to the reactor. The reaction was carried out at 70℃ for 3 hours. The product was collected, washed, and dried to obtain 155g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0077] Example 9

[0078] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 40g of ethyl acrylate, 15g of furfuryl acrylate A, and 0.01g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 1MPa, and the reaction was carried out at 0℃ for 0.1h. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 4g of coupling agent C was added to the reactor. The reaction was carried out at 40℃ for 0.1h. The product was collected, washed, and dried. The composition of the obtained polymer is shown in Table 1, and the basic properties are shown in Table 2.

[0079] Example 10

[0080] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 40g of ethyl acrylate, 15g of furfuryl acrylate A, and 0.5g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 50MPa, and the reaction was carried out at 50℃ for 6 hours. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 4g of coupling agent C was added to the reactor. The reaction was carried out at 60℃ for 5 hours. The product was collected, washed, and dried. The composition of the resulting polymer is shown in Table 1, and its basic properties are shown in Table 2.

[0081] Example 11

[0082] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 40g of ethyl acrylate, 15g of furfuryl acrylate A, and 1g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 100MPa, and the reaction was carried out at 100℃ for 12h. After the reaction, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 4g of coupling agent C was added to the reactor. The reaction was carried out at 80℃ for 12h. The product was collected, washed, and dried. The composition of the obtained polymer is shown in Table 1, and its basic properties are shown in Table 2.

[0083] Comparative Example 1

[0084] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 40g of ethyl acrylate, and 0.5g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 10MPa, and the reaction was carried out at 70℃ for 3 hours. After the reaction was completed, the product was collected, washed, and dried to obtain 150g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0085] Comparative Example 2

[0086] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 40g of ethyl acrylate, 15g of furfuryl acrylate A, and 0.5g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 10MPa, and the reaction was carried out at 70℃ for 3 hours. After the reaction was completed, the product was collected, washed, and dried to obtain 151g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0087] Comparative Example 3

[0088] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 40g of ethyl acrylate, and 0.5g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 10MPa, and the reaction was carried out at 70℃ for 3 hours. After the reaction was completed, the ethylene in the reactor was vented, and 10mL of a hexane solution containing 4.0g of coupling agent C was added to the reactor. The reaction was carried out at 70℃ for 3 hours. The product was collected, washed, and dried to obtain 165g of product. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0089] Comparative Example 4

[0090] In a 2L reactor, 200mL of toluene, 45g of methyl acrylate, 40g of ethyl acrylate, 15g of acrylic acid, and 0.5g of azobisisobutyronitrile (AIB) initiator were added. Ethylene gas was introduced at 10MPa, and the reaction was carried out at 70℃ for 3 hours. After the reaction was completed, the product was collected, washed, and dried to obtain 162g of product. The obtained product was subjected to conventional vulcanization crosslinking, and its mechanical properties were tested. The polymer composition is shown in Table 1, and the basic properties are shown in Table 2.

[0091] Table 1

[0092]

[0093]

[0094] Table 2

[0095]

[0096]

[0097] The cross-linked acrylate copolymer prepared by the method of the present invention has a cross-linked network structure formed by reversible chemical bonds. The cross-linked network formed in the material can be verified by gel testing. The tensile strength of the material is significantly higher than that of the samples of Comparative Examples 1-3 without a cross-linked network structure. For example, by comparing Example 2 with Comparative Examples 1-3, it can be seen that the gel content of the cross-linked acrylate copolymer prepared in Example 2 is as high as 97 wt%, while the gel content of the uncross-linked Comparative Examples 1-3 is 0. The tensile strength of the copolymer prepared in Example 2 is significantly higher than that of the samples with similar composition prepared in Comparative Examples 1-3. With the formation of the cross-linked structure, the elongation at break of the material is lower than that of the uncross-linked Comparative Examples 1-3, but the tensile strength of the prepared copolymer is comparable to that of the traditional vulcanized cross-linked sample (Comparative Example 4), and the elongation at break is much higher than that of the traditional vulcanized cross-linked sample. These all demonstrate that the reversible cross-linked chemical structure formed by the various components of the present invention can replace the traditional irreversible cross-linking method, and while maintaining the basic mechanical properties of the material, the elasticity and toughness of the material are significantly improved.

[0098] Furthermore, a comparative analysis of the results from Examples 2, 2', and 2" with Comparative Example 4 shows that the present invention forms reversible chemical bonds between the macromolecules of the acrylate copolymer through a thermally reversible reaction between furan and maleimide. These chemical bonds can dissociate through a reverse reaction at high temperatures, thereby de-crosslinking the crosslinked acrylate copolymer and endowing the crosslinked polymer with reprocessability. That is, the sample prepared in Example 2 can be repeatedly processed to obtain the sample in Example 2', and the sample in Example 2' can be further processed to obtain the sample in Example 2"; simultaneously, the data in Table 2 shows that the mechanical properties of the samples in Examples 2' and 2" remain essentially unchanged compared to the sample in Example 2. This indicates that the reversible crosslinking of the present invention can endow the material with multiple processing capabilities, and the material's properties can still be maintained after processing. However, the traditional vulcanized crosslinked sample (Comparative Example 4) cannot be repeatedly processed once the material is formed because the crosslinked chemical bonds are not reversible. Therefore, the present invention can achieve the green recycling and reuse of crosslinked rubber.

[0099] FTIR testing was performed using a Nicolet 6700 Fourier transform infrared spectrometer. The thermal reversibility of the DA reaction was observed through infrared spectroscopy, and the results are as follows: Figure 2 As shown, in the six-membered ring produced by the DA reaction, the in-plane bending vibration of the ether bond COC appears at 1177 cm⁻¹. -1 Nearby. Variable-temperature FTIR testing allows for a clearer observation of the formation and breakage of DA bonds in the sample as temperature changes. The reversible cross-linked sample prepared in Example 2 was subjected to variable-temperature infrared spectroscopy: the cross-linked sample was heated to 140°C for infrared data scanning, and the reverse DA reaction occurred. Figure 2 The middle is located at 1177cm-1 The intensity of the characteristic peak of the COC bond in the six-membered ring introduced by the DA reaction at the site decreases with increasing temperature; when the decrosslinked sample at 140℃ is further cooled to 40℃, the intensity of the peak at 1177 cm⁻¹ decreases. -1 The characteristic strength of the COC bond in the six-membered ring at the point of reaction increases again, indicating that the DA reaction has occurred. This demonstrates that the reversible process of DA reaction involving dissociation upon heating and association upon cooling was successfully achieved in the acrylate rubber prepared according to this invention.

[0100] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A crosslinked acrylate copolymer, characterized in that, The copolymer comprises structural unit A from acrylate, structural unit B from ethylene, structural unit C from furan-substituted acrylate, and structural unit D from coupling agent, wherein the acrylate is methyl acrylate and ethyl acrylate. Based on the total amount of the copolymer, the content of structural unit A is 10-60 wt%, the content of structural unit B is 30-82 wt%, the content of structural unit C is 5-9 wt%, and the content of structural unit D is 1-5 wt%. The furan-substituted acrylate is selected from and / or ; The coupling agent is selected from... and / or , where R is an alkylene group with 1-10 carbons; The method for preparing the crosslinked acrylate copolymer includes: in the presence of an initiator, polymerizing acrylate, furan-substituted acrylate and ethylene, venting ethylene after the reaction, and then adding a coupling agent to carry out a crosslinking reaction to obtain the crosslinked acrylate copolymer.

2. The crosslinked acrylate copolymer according to claim 1, characterized in that, The gel content of the copolymer is not less than The copolymer in the infrared spectrum Ether bonds appear nearby Characteristic peaks.

3. The crosslinked acrylate copolymer according to claim 1 or 2, characterized in that, The elongation at break of the copolymer is not less than 180%.

4. The crosslinked acrylate copolymer according to claim 3, characterized in that, The furan-substituted acrylate is .

5. A method for preparing the crosslinked acrylate copolymer according to any one of claims 1-4, characterized in that, In the presence of an initiator, acrylates, furan-substituted acrylates, and ethylene are polymerized. After the reaction is complete, the ethylene is vented, and a coupling agent is added to carry out a crosslinking reaction to obtain a crosslinked acrylate copolymer.

6. The preparation method according to claim 5, characterized in that, The mass ratio of the furan-substituted acrylate to the acrylate is 1:9-3:

8.

7. The preparation method according to claim 6, characterized in that, The pressure of the ethylene is 1-100 MPa.

8. The preparation method according to any one of claims 5-7, characterized in that, The amount of the initiator is 0.01%-1 wt% of the total mass of acrylate and furan-substituted acrylate.

9. The preparation method according to claim 8, characterized in that, The polymerization reaction is carried out at a temperature of 0-100℃ for a time of 0.1-12h.

10. The preparation method according to claim 8, characterized in that, The mass ratio of the coupling agent to the furan-substituted acrylate is 0.1-0.5:1; And / or, the crosslinking reaction is carried out at a temperature of 40-80°C for a time of 0.1-12 h.

11. The use of a crosslinked acrylate copolymer according to any one of claims 1-4 or a crosslinked acrylate copolymer prepared by any one of claims 5-10 as a reinforced acrylate rubber material.

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