Acrylic resin and preparation method and application thereof

Abstract

The present invention relates to the field of coating technology, and in particular to an acrylic resin and a preparation method and application thereof. The acrylic resin of the present invention is obtained by copolymerizing an acrylic ester monomer containing fluoranes with an acrylic ester monomer containing a phenolic structure, so that the acrylic resin has a temperature-sensitive effect and can change color at a specific temperature, and can be applied to the coating field that requires color change.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to an acrylic resin and a preparation method and application thereof. Background Art

[0002] Coatings are a very strong industry in the field of polymer materials and have been thriving for a long time. With the rapid development of the national economy, my country has become the world's largest producer and consumer of coatings, but there is little research on the development of multifunctional coatings, such as thermochromic coatings, that is, coatings that change color with temperature. This type of coating can be used in toys, installations, anti-counterfeiting and other fields.

[0003] Acrylic resin refers to homopolymers of acrylic acid esters or methacrylates and copolymers with other olefin monomers. Compared with other synthetic polymer resins, acrylic resin has many outstanding advantages, such as excellent light resistance, weather resistance, strong durability for outdoor exposure, resistance to ultraviolet light, not easy to decompose and yellow, can maintain the original gloss and color for a long time, good heat resistance, decomposition and no discoloration at 170°C, and still no discoloration at about 230°C or higher. It is light in color, water-white and transparent, corrosion-resistant, and has good resistance to staining and corrosion by chemicals such as acids, alkalis, salts, greases and detergents, excellent flexibility and minimum pigment reactivity. Therefore, it is widely used in industries such as automobiles, home appliances, metal furniture, coil industry, instrumentation, construction, textiles, wood products, papermaking and plastics. At the same time, in general leuco dyes, when their physical and chemical conditions change, they will change from colorless to colored. The current mainstream view is that the color change mechanism is that the leuco dye reacts with the developer to change the degree of conjugation of the system and thus change the color of the dye. For example, fluorane dyes as leucochromes need to be mixed with color developers and solvents to form a compound to achieve thermoreversible color change. However, in the coatings industry, such research has not been reported.

[0004] The main use of fluorane materials is as pressure-sensitive and heat-sensitive dyes. Many kinds of heat-sensitive dyes have been developed in various countries around the world. Their main chemical structures include phthalones, phenothiazines, phenoxazines, amides, spiropyrans, triarylmethanes and fluoranes, among which fluorane functional materials are the mainstream of heat-sensitive dyes, accounting for two-thirds of heat-sensitive dyes, and are considered to be the most promising next-generation pressure-sensitive dyes. However, as a recessive dye, a color developer must be added to develop color, which limits its application and promotion in certain occasions. Summary of the invention

[0005] The object of the present invention is to provide an acrylic resin and a preparation method and application thereof. The acrylic resin has a temperature-sensitive effect and can change color at a specific temperature.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides an acrylic resin having a structure shown in Formula I:

[0008]

[0009] Wherein, R1, R2, R3 and R4 are independently C1-20 alkyl or aryl groups, x is an integer of 1-100, and y is an integer of 1-100.

[0010] Preferably, the acrylic resin has a structure shown in any one of Formula T-1 to Formula T-6:

[0011]

[0012] The present invention also provides a method for preparing the acrylic resin described in the above technical solution, comprising the following steps:

[0013] Performing a ring-opening reaction on phthalic anhydride and a compound having a structure shown in Formula 2 to obtain a compound having a structure shown in Formula 3; the phthalic anhydride has a structure shown in Formula 1;

[0014] Carrying out a cyclization reaction between the compound having the structure shown in Formula 3 and the compound having the structure shown in Formula 4 to obtain a compound having the structure shown in Formula 5;

[0015] The compound having the structure shown in Formula 5 and the compound having the structure shown in Formula 6 are subjected to a free radical polymerization reaction to obtain the acrylic resin;

[0016]

[0017]

[0018] In formulae 2 to 6, R1, R2, R3 and R4 are independently C1-20 alkyl or aryl groups.

[0019] Preferably, the molar ratio of the phthalic anhydride to the compound having the structure shown in Formula 2 is 1:1.

[0020] Preferably, the ring-opening reaction is carried out at a temperature of 80 to 120° C. and for a time of 0.5 to 12 h.

[0021] Preferably, the molar ratio of the compound having the structure shown in Formula 3 to the compound having the structure shown in Formula 4 is 1:1.

[0022] Preferably, the temperature of the cyclization reaction is 120° C. and the time is 0.5 to 20 h.

[0023] Preferably, the molar ratio of the compound having the structure represented by Formula 5 to the compound having the structure represented by Formula 6 is (0.1-1):(1-0.1).

[0024] Preferably, the free radical polymerization reaction is carried out under the condition of adding an initiator;

[0025] The temperature of the free radical polymerization reaction is 80° C. and the time is 1 to 36 hours.

[0026] The present invention also provides the use of the acrylic resin described in the above technical solution or the acrylic resin prepared by the preparation method described in the above technical solution in coatings.

[0027] The present invention provides an acrylic resin having a structure shown in Formula I:

[0028]

[0029] Wherein, R1, R2, R3 and R4 are independently C1-20 alkyl or aryl groups, x is an integer of 1-100, and y is an integer of 1-100.

[0030] In the present invention, the acrylic resin is obtained by copolymerizing an acrylic ester monomer containing fluoranes with an acrylic ester monomer containing a phenolic structure, so that the acrylic resin has a temperature-sensitive effect and can change color at a specific temperature, and can be used in coating fields that require color changes. DETAILED DESCRIPTION

[0031] The present invention provides an acrylic resin having a structure shown in Formula I:

[0032]

[0033] Wherein, R1, R2, R3 and R4 are independently C1-20 alkyl or aryl groups, x is an integer of 1-100, and y is an integer of 1-100.

[0034] In the present invention, the color-changing functional group and the color-developing functional group structure in the acrylic resin are as shown in Formula II:

[0035]

[0036] In the present invention, the acrylic resin preferably has a structure shown in any one of Formulas T-1 to T-6:

[0037]

[0038] The present invention also provides a method for preparing the acrylic resin described in the above technical solution, comprising the following steps:

[0039] Performing a ring-opening reaction on phthalic anhydride and a compound having a structure shown in Formula 2 to obtain a compound having a structure shown in Formula 3; the phthalic anhydride has a structure shown in Formula 1;

[0040] Carrying out a cyclization reaction between the compound having the structure shown in Formula 3 and the compound having the structure shown in Formula 4 to obtain a compound having the structure shown in Formula 5;

[0041] The compound having the structure shown in Formula 5 and the compound having the structure shown in Formula 6 are subjected to a free radical polymerization reaction to obtain the acrylic resin;

[0042]

[0043]

[0044] In formulae 2 to 6, R1, R2, R3 and R4 are independently C1-20 alkyl or aryl groups.

[0045] In the present invention, the preparation process of the acrylic resin is shown in Formula 7:

[0046]

[0047] In the present invention, unless otherwise specified, all preparation of raw materials can be carried out by processes well known to those skilled in the art.

[0048] The present invention conducts a ring-opening reaction between phthalic anhydride and a compound having a structure shown in Formula 2 to obtain a compound having a structure shown in Formula 3; the phthalic anhydride has a structure shown in Formula 1.

[0049] In the present invention, the molar ratio of the phthalic anhydride to the compound having the structure represented by Formula 2 is preferably 1:1.

[0050] In the present invention, the ring-opening reaction is preferably carried out in an organic solvent, and the type of the organic solvent preferably includes substituted or unsubstituted aromatic hydrocarbons, and more preferably includes one or more of benzene, toluene, xylene, trimethylbenzene, chlorobenzene and dichlorobenzene; when the organic solvent is two or more of the above specific selections, the present invention has no special restrictions on the ratio of the above specific substances, and they can be mixed in any ratio. The present invention has no special restrictions on the amount of the organic solvent, and the amount well known to those skilled in the art can be used.

[0051] In the present invention, the ring-opening reaction is preferably carried out in a nitrogen atmosphere; the ring-opening reaction is preferably carried out under heating reflux conditions, the temperature of the ring-opening reaction is preferably 80-120°C, more preferably 100°C; the time is preferably 0.5-12h, more preferably 3h.

[0052] After the ring-opening reaction is completed, the present invention also preferably includes post-treatment, and the post-treatment preferably includes pouring the reaction product obtained by the ring-opening reaction into ice water, neutralizing it with hydrochloric acid in sequence, extracting it with chloroform, combining the organic phases, drying it with anhydrous sodium sulfate, concentrating to remove the solvent, and recrystallizing it. The reagent used for the recrystallization is preferably a mixture of dichloromethane and petroleum ether; the volume ratio of dichloromethane and petroleum ether in the mixture is preferably (1-10): (10-1), more preferably (2-8): (8-2), and most preferably (3-6): (6-3).

[0053] After obtaining the compound having the structure shown in Formula 3, the present invention performs a cyclization reaction on the compound having the structure shown in Formula 3 and the compound having the structure shown in Formula 4 to obtain the compound having the structure shown in Formula 5.

[0054] In the present invention, the molar ratio of the compound having the structure represented by Formula 3 to the compound having the structure represented by Formula 4 is preferably 1:1.

[0055] In the present invention, the cyclization reaction is preferably carried out in sulfuric acid with a mass concentration of 85%; the volume ratio of the substance having the structural compound shown in Formula 3 to the sulfuric acid with a mass concentration of 85% is preferably 0.05 mol:50 mL.

[0056] In the present invention, the mixture of the compound having the structure shown in Formula 3, the compound having the structure shown in Formula 4 and sulfuric acid with a mass concentration of 85% is preferably prepared by mixing the compound having the structure shown in Formula 3 with the compound having the structure shown in Formula 4 and then adding the sulfuric acid with a mass concentration of 85%.

[0057] In the present invention, the temperature of the cyclization reaction is preferably 120°C, the time is preferably 0.5 to 20 hours, more preferably 5 to 15 hours, and most preferably 8 to 12 hours. In the present invention, the cyclization reaction is preferably carried out under stirring conditions, and the present invention has no special restrictions on the stirring process, and the process well known to those skilled in the art can be used.

[0058] After the cyclization reaction is completed, the present invention preferably further comprises post-treatment of the obtained product system; the post-treatment preferably comprises: cooling the obtained product system to room temperature, pouring it into ice water, neutralizing it with a 2 mol / L sodium hydroxide solution, filtering, dispersing the obtained filter cake into toluene and a 2 mol / L sodium hydroxide solution, stirring at 120° C. for 1 to 5 hours, separating the liquids, drying the obtained organic phase with anhydrous sodium sulfate, concentrating it, and recrystallizing the obtained crude product; the reagent used for the recrystallization is preferably a mixture of dichloromethane and petroleum ether; the volume ratio of dichloromethane to petroleum ether in the mixture is preferably (1 to 10): (10 to 1), more preferably (2 to 8): (8 to 2), and most preferably (3 to 6): (6 to 3).

[0059] After obtaining the compound having the structure shown in Formula 5, the present invention conducts a free radical polymerization reaction between the compound having the structure shown in Formula 5 and the compound having the structure shown in Formula 6 to obtain the acrylic resin.

[0060] In the present invention, the molar ratio of the compound having the structure represented by Formula 5 to the compound having the structure represented by Formula 6 is preferably (0.1-1):(1-0.1), more preferably (0.2-0.9):(0.9-0.2), and most preferably (0.3-0.6):(0.6-0.3).

[0061] In the present invention, the free radical polymerization reaction is preferably carried out in an organic solvent, and the organic solvent preferably includes one or more of anhydrous methanol, ethanol, propanol, ethylene glycol and butanol; when the organic solvent is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and can be mixed in any ratio. The present invention does not have any special restrictions on the amount of the organic solvent, and the amount familiar to those skilled in the art can be used to ensure that the compound having the structure shown in Formula 5 and the compound having the structure shown in Formula 6 are fully dissolved.

[0062] In the present invention, the free radical polymerization reaction is preferably carried out under the condition of adding an initiator, and the initiator preferably includes one or more of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile and dimethyl azobisisobutyrate; when the initiator is two or more of the above-mentioned specific selections, the present invention has no special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0063] In the present invention, the temperature of the free radical polymerization reaction is preferably 80°C, the time is preferably 1 to 36 hours, and more preferably 10 to 20 hours; the free radical polymerization reaction is preferably carried out under stirring conditions. The present invention does not have any special limitation on the stirring process, and the process familiar to those skilled in the art can be used.

[0064] In the present invention, the free radical polymerization process preferably includes: dissolving the compound having the structure shown in Formula 5 and the compound having the structure shown in Formula 6 in an organic solvent, adding an initiator dropwise under stirring, and heating to 80° C. to carry out a free radical polymerization reaction.

[0065] After the free radical polymerization reaction is completed, the present invention also preferably includes post-processing the obtained product system; the post-processing preferably includes: concentrating the obtained product system to remove the organic solvent, precipitating the solid with acetone, and finally vacuum drying at 80°C.

[0066] The present invention also provides the use of the acrylic resin described in the above technical solution or the acrylic resin prepared by the preparation method described in the above technical solution in coatings. The present invention has no special limitation on the method of the application, and the method well known to those skilled in the art can be used.

[0067] The acrylic resin provided by the present invention and its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0068] Example 1

[0069] Synthesis of acrylic resin material T-1:

[0070]

[0071] 14.8g (0.1mol) of phthalic anhydride and 16.5g (0.1mol) of 3-diethylaminophenol were dissolved in 300mL of toluene, heated under reflux for 3h under nitrogen, and then 100mL of 8mol / L sodium hydroxide solution was added dropwise, and heated at 100°C for 5h. After the reaction was completed, the reaction mixture was poured into ice water, neutralized with hydrochloric acid, extracted with chloroform, the organic phases were combined, dried with anhydrous sodium sulfate, and concentrated to remove the solvent to obtain a crude product, which was recrystallized from dichloromethane / petroleum ether to obtain 22.4g of 2-(4-diethylamino-2-hydroxybenzoyl)-benzoic acid (1-3). 1 H NMR (500MHz, CDCl3) δ8.43(d,J=15.0Hz,1H),8.18(d,J=14.8Hz,1H),7.95(t,J=14.9Hz,1H),7.80(t,J=14.9Hz,1H), 7.13(d,J=15.0Hz,1H),6.48(d,J=14.9Hz,1H),6.32(d,J=3.1Hz,1H),3.36(q,J=12.6Hz,2H),1.12(t,J=12.6Hz,3H);

[0072] In a 500L round-bottom flask, 15.6g (0.05mol) of 2-(4-diethylamino-2-hydroxybenzoyl)-benzoic acid (1-3) and 8.9g (0.05mol) of methyl p-hydroxyphenylacrylate (1-4) were added, and then 50mL of 85% sulfuric acid was added, and the mixture was stirred and heated at 120°C for 10 hours. After cooling to room temperature, the mixture was poured into ice water, neutralized with 2mol / L sodium hydroxide solution, filtered, and the filter cake was dispersed in 100mL of toluene and 50mL of 2mol / L sodium hydroxide solution, stirred at 120°C for 2 hours, separated, and the organic phase was dried with anhydrous sodium sulfate and concentrated to obtain a crude product. The crude product was recrystallized with a mixed solution of dichloromethane and petroleum ether in a volume ratio of 1:8 to obtain 18.7g of a methacrylate monomer compound (1-5) containing a fluorane functional group. 1 HNMR (500MHz, CDCl3) δ7.87(dd,J=14.7,3.1Hz,1H),7.58–7.32(m,4H),7.24(d,J=2.9Hz,1H),7.12(d,J=14.9Hz,1H),6.95(d,J=15.0Hz,1H),6.43(dd ,J=15.0,2.9Hz,1H),6.27(d,J=3.1Hz,1H),5.97(d,J=4.2Hz,1H),5.53(d, J=4.2Hz,1H),3.69(s,3H),3.36(q,J=12.6Hz,4H),1.12(t,J=12.6Hz,6H);

[0073] 18.2 g (0.04 mol) of a fluorane functional group-containing methyl acrylate monomer compound (1-5) and 7.1 g (0.04 mol) of methyl p-hydroxyphenylacrylate (1-6) were dissolved in 200 mL of anhydrous methanol. Under stirring, a catalytic amount of initiator azobisisobutyronitrile AIBN (0.13 g AIBN dissolved in 10 mL of methanol) was added dropwise. The mixture was stirred at 80°C for overnight reaction. After the reaction was completed, the solvent was removed by concentration. The solid was precipitated with acetone and dried under vacuum at 80°C to obtain 22.5 g of the target acrylic polymer material T-1. 1 H NMR(500MHz, CDCl3)δ7.87(s,1H),7.59–7.27(m,7H),7.18(s,1H),7.12(s,1H),6.75(s,2H),6.43 (s,1H),6.27(s,1H),4.73(s,1H),3.67(s,6H),3.36(s,4H),1.89(d,J=14.2Hz,2H),1.12(s,6H).

[0074] Example 2

[0075] Synthesis of acrylic resin material T-2:

[0076]

[0077] In a 500L round-bottom flask, 15.6g (0.05mol) of 2-(4-diethylamino-2-hydroxybenzoyl)-benzoic acid and 9.8g (0.05mol) of ethyl p-hydroxyphenylacrylate (2-1) were added, and then 50mL of 85% sulfuric acid was added, and the mixture was stirred and heated at 120°C for 10 hours. After cooling to room temperature, the mixture was poured into ice water, neutralized with 2mol / L sodium hydroxide solution, filtered, and the filter cake was dispersed in 100mL of toluene and 50mL of 2mol / L sodium hydroxide solution, stirred at 120°C for 2 hours, separated, and the organic phase was dried over anhydrous sodium sulfate and concentrated to obtain a crude product. The crude product was recrystallized from a mixture of dichloromethane and petroleum ether in a volume ratio of 1:8 to obtain 19.1g of a methacrylate monomer compound (2-2) containing a fluorane functional group. 1 H NMR (500MHz, CDCl3) δ7.87(dd,J=14.7,3.1Hz,1H),7.59–7.32(m,4H),7.24(d,J=2.9Hz,1H),7.12(d,J=14.9Hz,1H),6.95(d,J=15.0Hz,1H),6.43(dd, J=15.0,2.9Hz,1H),6.29(dd,J=16.8,3.7Hz,2H),6.20(d,J=4.2Hz,1H),4. 00(q,J=11.9Hz,2H),3.36(q,J=12.6Hz,4H),1.10(dt,J=24.2,12.2Hz,9H);

[0078] 18.7 g (0.04 mol) of a fluorane functional group-containing methyl acrylate monomer compound (2-2) and 7.7 g (0.04 mol) of ethyl p-hydroxyphenylacrylate (2-3) were dissolved in 200 mL of anhydrous methanol. Under stirring, a catalytic amount of initiator azobisisobutyronitrile AIBN (0.13 g AIBN dissolved in 10 mL of methanol) was added dropwise. The reaction was stirred at 80°C overnight. After the reaction was completed, the solvent was concentrated to remove the solvent, and the solid was precipitated with acetone. The solid was dried under vacuum at 80°C to obtain 24.2 g of the target acrylic polymer material T-2. 1H NMR(500MHz, CDCl3)δ7.87(dd,J=14.7,3.1Hz,1H),7.61–7.27(m,1H),7.18( d,J=2.1Hz,1H),7.12(d,J=14.9Hz,1H),6.81–6.69(m,1H),6.43(dd,J=15.0 ,2.9Hz,1H),6.27(d,J=3.1Hz,1H),4.71(s,1H),4.29–4.13(m,1H),3.48–3. 26(m,1H),2.03(d,J=11.4Hz,1H),1.74(d,J=11.4Hz,1H),1.28–1.05(m,1H).

[0079] Example 3

[0080] Synthesis of acrylic resin material T-3:

[0081]

[0082] In a 500L round-bottom flask, 15.6g (0.05mol) of 2-(4-diethylamino-2-hydroxybenzoyl)-benzoic acid and 10.3g (0.05mol) of p-hydroxyphenyl propyl acrylate (3-1) were added, and then 50mL of 85% sulfuric acid was added, and the mixture was stirred and heated at 120°C for 10 hours. After cooling to room temperature, the mixture was poured into ice water, neutralized with 2mol / L sodium hydroxide solution, filtered, and the filter cake was dispersed in 100mL of toluene and 50mL of 2mol / L sodium hydroxide solution, stirred at 120°C for 2 hours, separated, and the organic phase was dried over anhydrous sodium sulfate and concentrated to obtain a crude product. The crude product was recrystallized from a mixture of dichloromethane and petroleum ether in a volume ratio of 1:8 to obtain 19.5g of a methacrylate monomer compound (3-2) containing a fluorane functional group. 1 H NMR(500MHz, CDCl3)δ7.87(dd,J=14.7,3.1Hz,1H),7.62–7.31(m,4H),7.24(d,J=2.9 Hz,1H),7.12(d,J=14.9Hz,1H),6.95(d,J=15.0Hz,1H),6.43(dd,J=15.0,2.9Hz,1H), 6.29(dd,J=18.5,3.7Hz,2H),6.07(d,J=4.2Hz,1H),4.12(t,J=13.6Hz,2H),3.36(q,J =12.6Hz, 4H), 1.73 (h, J = 13.4Hz, 2H), 1.12 (t, J = 12.6Hz, 6H), 1.01 (t, J = 13.4Hz, 3H);

[0083] 19.3 g (0.04 mol) of a fluorane functional group-containing methyl acrylate monomer compound (3-2) and 7.7 g (0.04 mol) of ethyl p-hydroxyphenylacrylate (3-3) were dissolved in 200 mL of anhydrous methanol. Under stirring, a catalytic amount of initiator azobisisobutyronitrile AIBN (0.13 g AIBN dissolved in 10 mL of methanol) was added dropwise. The mixture was stirred and reacted at 80°C overnight. After the reaction was completed, the solvent was removed by concentration. The solid was precipitated with acetone and dried under vacuum at 80°C to obtain 21.5 g of the target acrylic polymer material T-3. 1 HNMR(500MHz, CDCl3)δ7.87(dd,J=14.7,3.1Hz,1H),7.62–7.24(m,7H),7.15(dd, J=29.8,8.5Hz,2H),6.78–6.62(m,2H),6.43(dd,J=15.0,2.9Hz,1H),6.27(d,J=3 .1Hz,1H),4.75(s,1H),4.21(q,J=13.1Hz,2H),4.04(t,J=13.9Hz,2H),3.36(qd, J=15.9,3.8Hz,4H),2.01(d,J=3.6Hz,2H),1.87–1.55(m,2H),1.33–0.83(m,12H).

[0084] Example 4

[0085] Synthesis of acrylic resin material T-4:

[0086]

[0087] In a 500L round-bottom flask, 15.6g (0.05mol) of 2-(4-diethylamino-2-hydroxybenzoyl)-benzoic acid and 10.3g (0.05mol) of isopropyl p-hydroxyphenylacrylate (4-1) were added, and then 50mL of 85% sulfuric acid was added, and the mixture was stirred and heated at 120°C for 10 hours. After cooling to room temperature, the mixture was poured into ice water, neutralized with 2mol / L sodium hydroxide solution, filtered, and the filter cake was dispersed in 100mL of toluene and 50mL of 2mol / L sodium hydroxide solution, stirred at 120°C for 2 hours, separated, and the organic phase was dried with anhydrous sodium sulfate and concentrated to obtain a crude product. The crude product was recrystallized with a mixed solution of dichloromethane and petroleum ether in a volume ratio of 1:8 to obtain 20.5g of a methacrylate monomer compound (4-2) containing a fluorane functional group. 1HNMR (500MHz, CDCl3) δ7.87(dd,J=14.7,3.1Hz,1H),7.59–7.31(m,4H),7.24(d,J=2.9Hz,1H),7.12(d,J=14.9Hz,1H),6.95(d,J=15.0Hz,1H),6.4 3(dd,J=15.0,2.9Hz,1H),6.28(dd,J=12.3,3.7Hz,2H),6.11(d,J=4.0Hz,1H),4.87(m,1H),3.36(q,J=12.6Hz,4H),1.11(dd,J=18.0,7.1Hz,12H);

[0088] 19.3 g (0.04 mol) of a fluorane functional group-containing methyl acrylate monomer compound (4-2) and 7.1 g (0.04 mol) of methyl p-hydroxyphenylacrylate (4-3) were dissolved in 200 mL of anhydrous methanol. Under stirring, a catalytic amount of initiator azobisisobutyronitrile AIBN (0.13 g AIBN dissolved in 10 mL of methanol) was added dropwise. The mixture was stirred at 80°C for overnight reaction. After the reaction was completed, the solvent was removed by concentration. The solid was precipitated with acetone and dried under vacuum at 80°C to obtain 20.5 g of the target acrylic polymer material T-4. 1 H NMR(500MHz, CDCl3)δ7.87(dd,J=14.7,3.1Hz,1H),7.59–7.28(m,7H),7.18(d,J =2.1Hz,1H),7.12(d,J=14.9Hz,1H),6.78–6.68(m,2H),6.43(dd,J=15.0,2.9Hz ,1H),6.27(d,J=3.1Hz,1H),5.09–4.79(m,1H),4.73(s,1H),3.67(s,3H),3.47– 3.18(m,4H),1.80(d,J=16.7Hz,1H),1.69(d,J=16.7Hz,1H),1.28–0.97(m,12H).

[0089] Example 5

[0090] Synthesis of acrylic resin material T-5:

[0091]

[0092] In a 500L round-bottom flask, 15.6g (0.05mol) of 2-(4-diethylamino-2-hydroxybenzoyl)-benzoic acid and 13.1g (0.05mol) of 2-ethylpentyl p-hydroxyphenylacrylate (5-1) were added, and then 50mL of 85% sulfuric acid was added, and the mixture was stirred and heated at 120°C for 10 hours. After cooling to room temperature, the mixture was poured into ice water, neutralized with 2mol / L sodium hydroxide solution, filtered, and the filter cake was dispersed in 100mL of toluene and 50mL of 2mol / L sodium hydroxide solution, stirred at 120°C for 2 hours, separated, and the organic phase was dried over anhydrous sodium sulfate and concentrated to obtain a crude product. The crude product was recrystallized with a mixed solution of dichloromethane and petroleum ether in a volume ratio of 1:8 to obtain 23.5g of a methacrylate monomer compound (5-2) containing a fluorane functional group. 1 H NMR(500MHz,CDCl3)δ7.87(s,1H),7.62–7.32(m,4H),7.24(s,1H),7.12(s,1H),6.95(s,1H),6.43(s,1H),6.26(t,J=32.0Hz,3H),4.5 0(s,1H),4.25(s,1H),3.36(s,4H),1.90(s,1H),1.55(s,2H),1.38(s,2H),1.21(d,J=9.8Hz,2H),1.12(s,6H),0.91(d,J=20.0Hz,6H);

[0093] 21.6 g (0.04 mol) of a fluorane functional group-containing methyl acrylate monomer compound (5-2) and 7.1 g (0.04 mol) of methyl p-hydroxyphenylacrylate (5-3) were dissolved in 200 mL of anhydrous methanol. Under stirring, a catalytic amount of initiator azobisisobutyronitrile AIBN (0.13 g AIBN dissolved in 10 mL of methanol) was added dropwise. The mixture was stirred at 80°C for overnight reaction. After the reaction was completed, the solvent was removed by concentration. The solid was precipitated with acetone and dried under vacuum at 80°C to obtain 21.5 g of the target acrylic polymer material T-5. 1H NMR(500MHz, CDCl3)δ7.87(dd,J=14.7,3.1Hz,1H),7.59–7.28(m,7H),7.18(d,J =2.1Hz,1H),7.12(d,J=14.9Hz,1H),6.78–6.68(m,2H),6.43(dd,J=15.0,2.9Hz ,1H),6.27(d,J=3.1Hz,1H),5.09–4.79(m,1H),4.73(s,1H),3.67(s,3H),3.47– 3.18(m,4H),1.80(d,J=16.7Hz,1H),1.69(d,J=16.7Hz,1H),1.28–0.97(m,12H).

[0094] Example 6

[0095] Synthesis of acrylic resin material T-6:

[0096]

[0097] In a 500L round-bottom flask, add 15.6g (0.05mol) of 2-(4-diethylamino-2-hydroxybenzoyl)-benzoic acid and 11.0g (0.05mol) of butyl p-hydroxyphenylacrylate (6-1), then add 50mL of 85% sulfuric acid, stir and heat at 120°C for 10 hours, cool to room temperature, pour into ice water, neutralize with 2mol / L sodium hydroxide solution, filter, disperse the filter cake into 100mL of toluene and 50mL of 2mol / L sodium hydroxide solution, stir at 120°C for 2 hours, separate the liquids, dry the organic phase with anhydrous sodium sulfate, concentrate, and obtain a crude product. The crude product is recrystallized from a mixture of dichloromethane and petroleum ether in a volume ratio of 1:8 to obtain 22.3g of a methacrylate monomer compound (6-2) containing a fluorane functional group. 1H NMR (500MHz, CDCl3) δ7.87 (dd, J=7.4, 1.5Hz, 1H), 7.53 (td, J=7.5, 1.5Hz, 1H), 7.45 (dd, J=7.4, 1.4Hz, 2H ),7.39(td,J=7.4,1.5Hz,1H),7.24(d,J=1.4Hz,1H),7.12(d,J=7.5Hz,1H),6.95(d,J=7.5Hz,1H),6.43(d d,J=7.5,1.4Hz,1H),6.28(dd,J=11.6,1.9Hz,2H),6.16(d,J=2.0Hz,1H),3.97(t,J=4.7Hz,2H),3.36(q,J =6.2Hz,4H),1.47(tt,J=7.9,4.7Hz,2H),1.24–1.15(m,2H),1.12(t,J=6.3Hz,6H),0.90(t,J=6.6Hz,3H).

[0098] 19.9 g (0.04 mol) of a fluorane functional group-containing methyl acrylate monomer compound (6-2) and 8.8 g (0.04 mol) of butyl p-hydroxyphenyl acrylate (2-3) were dissolved in 200 mL of anhydrous methanol. Under stirring, a catalytic amount of initiator azobisisobutyronitrile AIBN (0.13 g AIBN dissolved in 10 mL of methanol) was added dropwise. The mixture was stirred at 80°C for overnight reaction. After the reaction was completed, the solvent was removed by concentration. The solid was precipitated with acetone and dried under vacuum at 80°C to obtain 23.5 g of the target acrylic polymer material T-6. 1H NMR(500MHz, CDCl3)δ7.87(s,1H),7.60–7.28(m,7H),7.18(s,1H),7.12(s,1H),6.75(s,2H),6.43(s,1H),6.27(s,1H),4 .75(s,1H),4.04(d,J=5.7Hz,4H),3.36(s,4H),1.96(d,J=23.9Hz,2H),1.47(d,J=70.0Hz,8H),1.12(s,6H),0.90(s,6H).

[0099] Comparative Example 1

[0100] Synthesis of methacrylate resin containing fluorane functional group (D-1):

[0101]

[0102] 18.2 g (0.04 mol) of fluorane functional group-containing methyl acrylate monomer compound (1-5) was dissolved in 200 mL of anhydrous methanol. Under stirring, a catalytic amount of initiator azobisisobutyronitrile AIBN (0.07 g AIBN dissolved in 10 mL of methanol) was added dropwise. The reaction was stirred at 80°C overnight. After the reaction was completed, the solvent was concentrated to remove the solvent, and the solid was precipitated with acetone. It was dried under vacuum at 80°C to obtain 14.5 g of the target acrylic polymer material D-1. 1 H NMR(500MHz, CDCl3)δ7.87(s,1H),7.60–7.32(m,5H),7.18(s,1H),7.12(s,1H) ,6.43(s,1H),6.27(s,1H),3.67(s,3H),3.36(s,4H),1.34(s,2H),1.12(s,6H).

[0103] Comparative Example 2

[0104] Synthesis of methacrylate resin containing phenolic hydroxyl functional groups (D-2):

[0105]

[0106] 7.1 (0.04 mol) methyl p-hydroxyphenylacrylate (1-6) was dissolved in 200 mL of anhydrous methanol. Under stirring, a catalytic amount of initiator azobisisobutyronitrile AIBN (0.07 g AIBN dissolved in 10 mL of methanol) was added dropwise. The reaction was stirred at 80°C overnight. After the reaction was completed, the solvent was concentrated to remove the solvent. The solid was precipitated with acetone and dried under vacuum at 80°C to obtain 5.6 g of the target acrylic polymer material D-2. 1H NMR (500MHz, CDCl3) δ7.33(s,2H),6.75(s,2H),4.73(s,1H),3.67(s,3H),1.39(s,2H).

[0107] Test Example 1

[0108] 0.5 g of the acrylic resin described in Examples 1 to 6 and Comparative Examples 1 to 2 was heated from room temperature to 200° C. at a heating rate of 1° C. / min, and then cooled to room temperature at a cooling rate of 1° C. / min. The color change was observed. The results are shown in Table 1:

[0109] Table 1 Color change temperature of acrylic resin described in Examples 1 to 6 and Comparative Examples 1 to 2

[0110] Example Color change temperature Example Color change temperature Example 1 46℃, pink to colorless Example 5 47℃, pink to colorless Example 2 43℃, pink to colorless Example 6 44℃, pink to colorless Example 3 51℃, pink to colorless Comparative Example 1 No color change Example 4 62℃, pink to colorless Comparative Example 2 No color change

[0111] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An acrylic resin, characterized in that It has the structure shown in formula I: Wherein, R1, R2, R3 and R4 are independently C1-20 alkyl or aryl groups, x is an integer of 1-100, and y is an integer of 1-100.

2. The acrylic resin according to claim 1, characterized in that The acrylic resin has a structure shown in any one of Formulas T-1 to T-6:

3. The method for preparing the acrylic resin according to claim 1 or 2, characterized in that: The following steps are involved: Performing a ring-opening reaction on phthalic anhydride and a compound having a structure shown in Formula 2 to obtain a compound having a structure shown in Formula 3; the phthalic anhydride has a structure shown in Formula 1; Carrying out a cyclization reaction between the compound having the structure shown in Formula 3 and the compound having the structure shown in Formula 4 to obtain a compound having the structure shown in Formula 5; The compound having the structure shown in Formula 5 and the compound having the structure shown in Formula 6 are subjected to a free radical polymerization reaction to obtain the acrylic resin; In formulae 2 to 6, R1, R2, R3 and R4 are independently C1-20 alkyl or aryl groups.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the phthalic anhydride to the compound having the structure shown in Formula 2 is 1:

1.

5. The preparation method according to claim 3 or 4, characterized in that: The temperature of the ring-opening reaction is 80-120° C., and the time is 0.5-12 hours.

6. The preparation method according to claim 3, characterized in that: The molar ratio of the compound having the structure shown in Formula 3 to the compound having the structure shown in Formula 4 is 1:

1.

7. The preparation method according to claim 3 or 6, characterized in that: The temperature of the cyclization reaction is 120° C. and the time is 0.5 to 20 hours.

8. The preparation method according to claim 3, characterized in that: The molar ratio of the compound having the structure represented by Formula 5 to the compound having the structure represented by Formula 6 is (0.1-1):(1-0.1).

9. The preparation method according to claim 3 or 8, characterized in that: The free radical polymerization reaction is carried out under the condition of adding an initiator; The temperature of the free radical polymerization reaction is 80° C. and the time is 1 to 36 hours.

10. Use of the acrylic resin according to claim 1 or 2 or the acrylic resin prepared by the preparation method according to any one of claims 3 to 9 in coatings.

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