A polyvinyl acetate resin-modified polyurethane dispersion and its preparation method

Abstract

The present invention discloses a polyvinyl acetate resin-modified polyurethane dispersion and a preparation method thereof, belonging to the technical field of organic synthesis. By respectively modifying furan and maleimide derivatives on the surface of polyvinyl acetate resin particles with surface hydroxylation treatment, and then doping the polyvinyl acetate resin particles with surface furan modification and the polyvinyl acetate resin particles with surface maleimide modification into polyurethane, the furyl group and amide group on the particle surface are made to undergo a D-A reaction (Diels-Alder reaction) by heating, so that the doped resin particles are linked into a network structure in polyurethane, causing the overall polymer dispersion system to harden; under heating or strong shear stress, the furyl group and amide group that have undergone the D-A reaction between the resin particles in polyurethane undergo a retro-Diels-Alder reaction to open the ring, causing the resin particle network in the corresponding region to disintegrate and the polyvinyl acetate resin-modified polyurethane dispersion to soften.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a polyvinyl acetate resin modified polyurethane dispersion and a preparation method thereof. Background Art

[0002] Polyurethane materials play a key role in many industrial fields with their excellent elasticity, wear resistance and environmental adaptability. The application of this polymer material in industries such as furniture, construction, footwear, transportation and home appliances not only improves the functionality and durability of products, but also promotes environmental protection and energy saving.

[0003] However, polyurethane materials still have some limitations in terms of mechanical properties. Currently, the mechanical properties of polyurethane can be improved through modification, but it will also bring some processing difficulties. Therefore, it is necessary to balance and optimize the mechanical properties and processing properties of polyurethane materials. How to modify polyurethane to reduce the processing difficulty of polyurethane materials, improve the processing and use efficiency of polyurethane materials, and further improve the environmental protection standards of polyurethane materials, so as to prepare a polyurethane material with excellent mechanical properties and easy processing, is of great significance to expanding the application range of polyurethane materials and meeting the specific application requirements of materials. Summary of the invention

[0004] To solve the above problems, the object of the present invention is to provide a polyvinyl acetate resin modified polyurethane dispersion and a preparation method thereof.

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

[0006] A polyvinyl acetate resin modified polyurethane dispersion is composed of the following raw materials in parts by weight: 1 part of polyvinyl acetate resin particles modified with furan on the surface, 1-1.2 parts of polyvinyl acetate resin particles modified with maleimide on the surface and 10-20 parts of polyurethane.

[0007] The surface furan-modified polyvinyl acetate resin particles are prepared according to the following method: by weight, 1 part of surface hydroxylated polyvinyl acetate resin particles and 0.1-1 part of terminal carboxyl furan derivatives are added to 10-15 parts of organic solvent 1, and then 0.1-1 part of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.02-0.2 part of 4-dimethylaminopyridine are added thereto, and the mixture is stirred and mixed evenly, and the mixture is heated to 25-80° C. to react for 12-24 hours. After the reaction is completed, the organic solvent is removed by reduced pressure distillation, and the residue is washed with organic solvent 1 and water for 3-5 times respectively, and dried to obtain surface furan-modified polyvinyl acetate resin particles.

[0008] The organic solvent 1 is dichloromethane, chloroform, acetonitrile or ethyl acetate.

[0009] The preparation method of the terminal carboxyl furan derivative comprises the following steps:

[0010] 1) By weight, add 1 part of methyl 3-bromopropionate and 0.6 - 1 part of furfuryl alcohol to 5 - 10 parts of organic solvent 2. After stirring and dissolving, add 0.7 - 2 parts of base 1 thereto, and react at 50 - 110 °C for 12 - 24 h. After the reaction is completed, add 8 - 10 parts of water to quench the reaction under ice bath, remove the solvent by reduced pressure distillation, wash the obtained residue with water 3 - 5 times, and dry to obtain Compound 1;

[0011] 2) Add 1 part of Compound 1 prepared in step 1) to 5 - 10 parts of alcohol solvent, then add 0.3 - 1 part of base 2, and react at 25 - 50 °C for 6 - 8 h. After the reaction is completed, remove the solvent by reduced pressure distillation, wash the obtained residue with water 3 - 5 times, and dry to obtain the terminal carboxyl furan derivative.

[0012] The organic solvent 2 in step 1) is dimethyl sulfoxide or dimethylformamide.

[0013] The base 1 in step 1) is sodium hydride, potassium hydride, sodium tert-butoxide or potassium tert-butoxide.

[0014] The alcohol solvent in step 2) is methanol or ethanol.

[0015] The base 2 in step 2) is sodium hydroxide or potassium hydroxide.

[0016] The preparation method of the surface hydroxylated polyvinyl acetate resin particles is as follows:

[0017] By weight, add 1 part of polyvinyl acetate resin to a mixed solvent of 5 - 10 parts of organic solvent 3 and alcohol solvent, then add 0.5 - 1.5 parts of base 2, and react at 25 - 50 °C for 12 - 24 h. After the reaction is completed, remove the solvent by reduced pressure distillation. After washing the obtained residue with water 3 - 5 times, add it to a mixed solution of 5 - 10 parts of chloroform and water to obtain a reaction solution. Then, introduce an inert gas into the reaction solution at a rate of 1 - 5 L / min, and stir the reaction solution at 5 - 50 r / min. After the solvent has evaporated completely, surface hydroxylated polyvinyl acetate resin particles are obtained.

[0018] The organic solvent 3 is tetrahydrofuran, chloroform, dichloromethane or acetone.

[0019] In the mixed solvent of organic solvent 3 and alcohol solvent, the mass ratio of organic solvent 3 to alcohol solvent is 1:1 - 2.

[0020] In the mixed solution of chloroform and water, the mass ratio of chloroform to water is 1 - 5:0.1.

[0021] The inert gas is nitrogen or argon.

[0022] The surface maleimide-modified polyvinyl acetate resin particles are prepared by the following method: by weight, 1 part of surface-hydroxylated polyvinyl acetate resin particles and 0.1 - 1.2 parts of carboxyl-terminated maleimide derivatives are added to 10 - 15 parts of organic solvent 1, then 0.08 - 0.8 part of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.015 - 0.16 part of 4-dimethylaminopyridine are added thereto, stirred and mixed evenly, heated to 25 - 80 °C for reaction for 12 - 24 h. After the reaction is completed, the organic solvent is removed by vacuum distillation, and the obtained residue is washed 3 - 5 times with organic solvent 1 and water respectively, and then dried to obtain the surface maleimide-modified polyvinyl acetate resin particles.

[0023] The preparation method of the carboxyl-terminated maleimide derivatives includes the following steps:

[0024] (1) By weight, 1 part of N-hydroxyethyl maleimide and 1.2 - 1.5 parts of methyl 3-bromopropionate are added to 8 - 15 parts of organic solvent 2, stirred and dissolved, then 0.8 - 1.5 parts of base 1 are added, and the reaction is carried out at 50 - 110 °C for 12 - 24 h. After the reaction is completed, 5 - 8 parts of water are added under ice bath to quench the reaction, the solvent is removed by vacuum distillation, and the obtained residue is washed 3 - 5 times with water and then dried to obtain compound 2;

[0025] (2) 1 part of compound 2 prepared in step (1) is added to 5 - 10 parts of alcohol solvent, then 0.25 - 1 part of base 2 is added, and the reaction is carried out at 25 - 50 °C for 6 - 8 h. After the reaction is completed, the solvent is removed by vacuum distillation, and the obtained residue is washed 3 - 5 times with water and then dried to obtain the carboxyl-terminated maleimide derivatives.

[0026] The preparation method of the polyvinyl acetate resin-modified polyurethane dispersion includes the following steps:

[0027] By weight, 1 part of surface-furan-modified polyvinyl acetate resin particles, 1 - 1.2 parts of surface-maleimide-modified polyvinyl acetate resin particles and 10 - 20 parts of polyurethane are added to 10 - 50 parts of organic solvent 3, heated to 50 - 70 °C, and mixed and reacted for 24 - 48 h, then filtered to obtain the polyvinyl acetate resin-modified polyurethane dispersion;

[0028] The organic solvent 3 is tetrahydrofuran, chloroform, dichloromethane or acetone.

[0029] The synthesis route of the present invention is as follows:

[0030] Synthesis of carboxyl-terminated furan derivatives:

[0031]

[0032] Synthesis of carboxyl-terminated maleimide derivatives:

[0033]

[0034] The present invention has the following advantages compared with the prior art:

[0035] For the polyvinyl acetate resin-modified polyurethane dispersion of the present invention, furan and maleimide derivatives are respectively modified on the surface of polyvinyl acetate resin particles with surface hydroxylation treatment, and then the polyvinyl acetate resin particles with surface furan modification and the polyvinyl acetate resin particles with surface maleimide modification are doped into the polyurethane. On the one hand, the introduction of polyvinyl acetate resin increases the flexibility, chemical stability and aging resistance of the material; on the other hand, by heating, the furyl group and amide group on the particle surface can undergo a Diels–Alder reaction (DA reaction), so that the doped resin particles are linked into a network structure in the polyurethane. Crosslinking modification can improve the mechanical properties, thermal stability and chemical stability of the material; under heating or strong shear stress, the furyl group and amide group that have undergone the DA reaction between the resin particles in the polyurethane undergo a retro-DA reaction to open the ring, causing the resin particle network in the corresponding area to disintegrate, softening the polyvinyl acetate resin-modified polyurethane dispersion, and improving the reprocessability of the material. The schematic diagram of the effect is as Figure 1 shown.

[0036] The polyvinyl acetate resin-modified polyurethane dispersion of the present invention has excellent mechanical properties, improves the processability of the material at the same time, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the reversible change effect of the polyvinyl acetate resin-modified polyurethane dispersion of the present invention under heating or strong shear stress conditions. DETAILED DESCRIPTION OF THE INVENTION

[0038] In order to better understand the technical solution of the present invention, the above content of the present invention will be further described in detail through specific embodiments in the form of examples below, but it should not be understood that the scope of the above subject matter of the present invention is limited to the following examples. All technologies implemented based on the above content of the present invention belong to the scope of the present invention.

[0039] The polyurethane used in this example is polyurethane of model WHT-1172IC purchased from Shenzhen Ruidasheng Plastic Co., Ltd.

[0040] Example 1

[0041] Preparation of polyvinyl acetate resin particles with surface hydroxylation treatment:

[0042] 0.1 kg of polyvinyl acetate resin was added to a mixed solvent of 0.5 kg of tetrahydrofuran and ethanol, and then 0.05 kg of sodium hydroxide was added thereto. The reaction was carried out at 25 °C for 12 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The obtained residue was washed with water three times and then added to a mixed solution of 0.5 kg of chloroform and water to obtain a reaction solution. Then, nitrogen gas was introduced into the reaction solution at a rate of 1 L / min, and the reaction solution was stirred at 5 r / min. After the solvent was completely volatilized, surface hydroxylated polyvinyl acetate resin particles were obtained.

[0043] In the mixed solvent of tetrahydrofuran and ethanol, the mass ratio of tetrahydrofuran to ethanol is 1:1.

[0044] In the mixed solution of chloroform and water, the mass ratio of chloroform to water is 1:0.1.

[0045] Preparation of carboxyl-terminal furan derivative:

[0046] 1) 0.1 kg of methyl 3-bromopropionate and 0.06 kg of furfuryl alcohol were added to 0.5 kg of dimethyl sulfoxide. After stirring and dissolving, 0.07 kg of sodium hydride was added thereto. The reaction was carried out at 50 °C for 24 h. After the reaction was completed, 0.8 kg of water was added under ice bath to quench the reaction. The solvent was removed by distillation under reduced pressure. The obtained residue was washed with water three times and dried to obtain Compound 1. 1 H NMR (300 MHz, DMSO-d6, 293 K): δ 7.59 (d, 1H), 6.35 - 6.51 (m, 2H), 4.44 (s, 2H), 3.68 (t, 2H), 3.56 (s, 3H), 2.45 (t, 2H).

[0047] 2) 0.1 kg of Compound 1 prepared in step 1) was added to 0.5 kg of methanol, and then 0.03 kg of sodium hydroxide was added. The reaction was carried out at 25 °C for 8 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The obtained residue was washed with water three times and dried to obtain the carboxyl-terminal furan derivative. 1 H NMR (300 MHz, DMSO-d6, 293 K): δ 12.05 (s, 1H), 7.57 (d, 1H), 6.32 - 6.52 (m, 2H), 4.46 (s, 2H), 3.65 (t, 2H), 2.42 (t, 2H).

[0048] Preparation of surface furan-modified polyvinyl acetate resin particles:

[0049] Add 0.1 kg of polyvinyl acetate resin particles with surface hydroxylation treatment and 0.01 kg of carboxyl-terminal furan derivative into 1 kg of dichloromethane. Then add 0.01 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.002 kg of 4-dimethylaminopyridine thereto, stir and mix evenly, heat to 25 °C and react for 24 h. After the reaction is completed, remove the organic solvent by distillation under reduced pressure. Wash the obtained residue three times with dichloromethane and water respectively, and dry it to obtain polyvinyl acetate resin particles with surface furan modification.

[0050] Preparation of carboxyl-terminal maleimide derivative:

[0051] (1) Add 0.1 kg of N-hydroxyethyl maleimide and 0.12 kg of methyl 3-bromopropionate into 0.8 kg of dimethyl sulfoxide. After stirring and dissolving, add 0.08 kg of sodium hydride and react at 50 °C for 24 h. After the reaction is completed, add 0.5 kg of water to quench the reaction under ice bath. Remove the solvent by distillation under reduced pressure. Wash the obtained residue three times with water and dry it to obtain Compound 2. 1 H NMR(300MHz,DMSO-d6,293K):δ7.79(s,2H),3.52 - 3.82(m,9H),2.40(t,2H).

[0052] (2) Add 0.1 kg of Compound 2 prepared in step (1) into 0.5 kg of methanol, then add 0.025 kg of sodium hydroxide and react at 25 °C for 8 h. After the reaction is completed, remove the solvent by distillation under reduced pressure. Wash the obtained residue three times with water and dry it to obtain the carboxyl-terminal maleimide derivative. 1 H NMR(300MHz,DMSO-d6,293K):δ12.02(s,1H),7.82(s,2H),3.61 - 3.77(m,6H),2.41(t,2H).

[0053] Preparation of polyvinyl acetate resin particles with surface maleimide modification:

[0054] Add 0.1 kg of polyvinyl acetate resin particles with surface hydroxylation treatment and 0.01 kg of carboxyl-terminal maleimide derivative into 1 kg of dichloromethane. Then add 0.008 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.0015 kg of 4-dimethylaminopyridine thereto, stir and mix evenly, heat to 25 °C and react for 24 h. After the reaction is completed, remove the organic solvent by distillation under reduced pressure. Wash the obtained residue three times with dichloromethane and water respectively, and dry it to obtain polyvinyl acetate resin particles with surface maleimide modification.

[0055] Preparation of polyvinyl acetate resin modified polyurethane dispersion:

[0056] Add 0.1 kg of polyvinyl acetate resin particles modified with surface furan, 0.1 kg of polyvinyl acetate resin particles modified with surface maleimide, and 1 kg of polyurethane into 1 kg of tetrahydrofuran, heat to 50 °C, carry out a mixing reaction for 48 h, and perform suction filtration to obtain a polyvinyl acetate resin-modified polyurethane dispersion.

[0057] Example 2

[0058] Preparation of polyvinyl acetate resin particles with surface hydroxylation treatment:

[0059] Add 0.1 kg of polyvinyl acetate resin into a mixed solvent of 0.7 kg of chloroform and methanol, then add 0.07 kg of potassium hydroxide thereto, react at 30 °C for 15 h. After the reaction is completed, remove the solvent by vacuum distillation. After the obtained residue is washed with water 5 times, add it into a mixed solution of 0.8 kg of chloroform and water to obtain a reaction solution. Then, pass argon into the reaction solution at a rate of 2 L / min, and stir the reaction solution at 20 r / min. After the solvent has completely evaporated, polyvinyl acetate resin particles with surface hydroxylation treatment are obtained.

[0060] The mass ratio of chloroform to methanol in the mixed solvent of chloroform and methanol is 1:1.5.

[0061] The mass ratio of chloroform to water in the mixed solution of chloroform and water is 2:0.1.

[0062] Preparation of carboxyl-terminal furan derivative:

[0063] 1) Add 0.1 kg of methyl 3-bromopropionate and 0.07 kg of furfuryl alcohol into 0.6 kg of dimethyl sulfoxide, stir to dissolve, then add 0.1 kg of potassium hydride thereto, react at 60 °C for 22 h. After the reaction is completed, add 0.85 kg of water to quench the reaction under an ice bath, remove the solvent by vacuum distillation. After the obtained residue is washed with water 4 times and dried, compound 1 is obtained;

[0064] 2) Add 0.1 kg of compound 1 prepared in step 1) into 0.6 kg of ethanol, then add 0.04 kg of potassium hydroxide, react at 30 °C for 7.5 h. After the reaction is completed, remove the solvent by vacuum distillation. After the obtained residue is washed with water 4 times and dried, a carboxyl-terminal furan derivative is obtained.

[0065] Preparation of polyvinyl acetate resin particles modified with surface furan:

[0066] Add 0.1 kg of polyvinyl acetate resin particles with surface hydroxylation treatment and 0.03 kg of carboxyl-terminal furan derivatives to 1.1 kg of chloroform. Then add 0.03 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.008 kg of 4-dimethylaminopyridine thereto, stir and mix evenly, heat to 35 °C and react for 22 h. After the reaction is completed, remove the organic solvent by vacuum distillation. The obtained residue is washed 4 times with chloroform and water respectively, and dried to obtain polyvinyl acetate resin particles with surface furan modification.

[0067] Preparation of carboxyl-terminal maleimide derivatives:

[0068] (1) Add 0.1 kg of N-hydroxyethyl maleimide and 0.13 kg of methyl 3-bromopropionate to 1 kg of dimethylformamide. After stirring and dissolving, add 0.1 kg of potassium hydride and react at 70 °C for 20 h. After the reaction is completed, add 0.65 kg of water under ice bath to quench the reaction. Remove the solvent by vacuum distillation. The obtained residue is washed 4 times with water and dried to obtain Compound 2.

[0069] (2) Add 0.1 kg of Compound 2 prepared in step (1) to 0.6 kg of ethanol, then add 0.05 kg of potassium hydroxide and react at 30 °C for 7.5 h. After the reaction is completed, remove the solvent by vacuum distillation. The obtained residue is washed 4 times with water and dried to obtain carboxyl-terminal maleimide derivatives.

[0070] Preparation of polyvinyl acetate resin particles with surface maleimide modification:

[0071] Add 0.1 kg of polyvinyl acetate resin particles with surface hydroxylation treatment and 0.04 kg of carboxyl-terminal maleimide derivatives to 1.1 kg of chloroform. Then add 0.01 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.008 kg of 4-dimethylaminopyridine thereto, stir and mix evenly, heat to 40 °C and react for 20 h. After the reaction is completed, remove the organic solvent by vacuum distillation. The obtained residue is washed 3 times with chloroform and water respectively, and dried to obtain polyvinyl acetate resin particles with surface maleimide modification.

[0072] Preparation of polyvinyl acetate resin-modified polyurethane dispersion:

[0073] Add 0.1 kg of polyvinyl acetate resin particles with surface furan modification, 0.11 kg of polyvinyl acetate resin particles with surface maleimide modification and 1.2 kg of polyurethane to 2 kg of dichloromethane, heat to 55 °C, mix and react for 40 h, and filter by suction to obtain polyvinyl acetate resin-modified polyurethane dispersion.

[0074] Example 3

[0075] Preparation of surface-hydroxylated polyvinyl acetate resin particles:

[0076] Add 0.1 kg of polyvinyl acetate resin to a mixed solvent of 0.9 kg of acetone and ethanol, then add 0.1 kg of potassium hydroxide thereto, react at 40 °C for 18 h. After the reaction is completed, remove the solvent by vacuum distillation. The obtained residue is washed with water 4 times and then added to a mixed solution of 0.9 kg of chloroform and water to obtain a reaction solution. Then, argon is introduced into the reaction solution at a rate of 3 L / min, and the reaction solution is stirred at 30 r / min. After the solvent has evaporated completely, surface-hydroxylated polyvinyl acetate resin particles are obtained.

[0077] The mass ratio of acetone to ethanol in the mixed solvent of acetone and ethanol is 1:1.8.

[0078] The mass ratio of chloroform to water in the mixed solution of chloroform and water is 3:0.1.

[0079] Preparation of carboxyl-terminal furan derivatives:

[0080] 1) Add 0.1 kg of methyl 3-bromopropionate and 0.08 kg of furfuryl alcohol to 0.7 kg of dimethylformamide, stir to dissolve, then add 0.14 kg of sodium tert-butoxide thereto, react at 80 °C for 18 h. After the reaction is completed, add 0.9 kg of water under ice bath to quench the reaction, remove the solvent by vacuum distillation. The obtained residue is washed with water 5 times and dried to obtain Compound 1.

[0081] 2) Add 0.1 kg of Compound 1 prepared in step 1) to 0.8 kg of ethanol, then add 0.06 kg of potassium hydroxide, react at 40 °C for 7 h. After the reaction is completed, remove the solvent by vacuum distillation. The obtained residue is washed with water 5 times and dried to obtain carboxyl-terminal furan derivatives.

[0082] Preparation of surface-furan-modified polyvinyl acetate resin particles:

[0083] Add 0.1 kg of surface-hydroxylated polyvinyl acetate resin particles and 0.06 kg of carboxyl-terminal furan derivatives to 1.3 kg of ethyl acetate, then add 0.06 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.014 kg of 4-dimethylaminopyridine, stir and mix evenly, heat to 50 °C and react for 18 h. After the reaction is completed, remove the organic solvent by vacuum distillation. The obtained residue is washed 5 times with ethyl acetate and water respectively and dried to obtain surface-furan-modified polyvinyl acetate resin particles.

[0084] Preparation of carboxyl-terminal maleimide derivatives:

[0085] (1) 0.1 kg of N - hydroxyethyl maleimide and 0.14 kg of methyl 3 - bromopropionate were added to 1.2 kg of dimethylformamide. After stirring and dissolving, 0.12 kg of sodium tert - butoxide was added, and the reaction was carried out at 90 °C for 16 h. After the reaction was completed, 0.7 kg of water was added under ice - bath conditions to quench the reaction. The solvent was removed by vacuum distillation, and the obtained residue was washed with water 5 times and then dried to obtain Compound 2;

[0086] (2) 0.1 kg of Compound 2 prepared in step (1) was added to 0.7 kg of ethanol, and then 0.07 kg of potassium hydroxide was added. The reaction was carried out at 40 °C for 7 h. After the reaction was completed, the solvent was removed by vacuum distillation, and the obtained residue was washed with water 5 times and then dried to obtain the carboxyl - terminated maleimide derivative.

[0087] Preparation of poly(vinyl acetate) resin particles modified with maleimide on the surface:

[0088] 0.1 kg of poly(vinyl acetate) resin particles with surface hydroxylation treatment and 0.06 kg of the carboxyl - terminated maleimide derivative were added to 1.3 kg of acetonitrile. Then, 0.05 kg of 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide and 0.01 kg of 4 - dimethylaminopyridine were added thereto. After stirring and mixing evenly, the mixture was heated to 55 °C and reacted for 18 h. After the reaction was completed, the organic solvent was removed by vacuum distillation, and the obtained residue was washed 4 times with acetonitrile and water respectively and then dried to obtain poly(vinyl acetate) resin particles modified with maleimide on the surface.

[0089] Preparation of poly(vinyl acetate) resin - modified polyurethane dispersion:

[0090] 0.1 kg of poly(vinyl acetate) resin particles modified with furan on the surface, 0.11 kg of poly(vinyl acetate) resin particles modified with maleimide on the surface and 1.5 kg of polyurethane were added to 3 kg of dichloromethane. The mixture was heated to 60 °C and reacted for 36 h. After filtration, a poly(vinyl acetate) resin - modified polyurethane dispersion was obtained.

[0091] Example 4

[0092] Preparation of poly(vinyl acetate) resin particles with surface hydroxylation treatment:

[0093] 0.1 kg of poly(vinyl acetate) resin was added to a mixed solvent of 1 kg of dichloromethane and ethanol. Then, 0.12 kg of potassium hydroxide was added thereto. The reaction was carried out at 45 °C for 22 h. After the reaction was completed, the solvent was removed by vacuum distillation. The obtained residue was washed with water 5 times and then added to a mixed solution of 0.9 kg of chloroform and water to obtain a reaction solution. Then, nitrogen gas was introduced into the reaction solution at a rate of 4 L / min, and the reaction solution was stirred at 40 r / min. After the solvent was completely evaporated, poly(vinyl acetate) resin particles with surface hydroxylation treatment were obtained.

[0094] In the mixed solvent of dichloromethane and ethanol, the mass ratio of dichloromethane to ethanol is 1:1.9.

[0095] In the mixed solution of chloroform and water, the mass ratio of chloroform to water is 4:0.1.

[0096] Preparation of terminal carboxyl furan derivative:

[0097] 1) Add 0.1 kg of methyl 3-bromopropionate and 0.09 kg of furfuryl alcohol to 0.9 kg of dimethylformamide. After stirring and dissolving, add 0.17 kg of potassium tert-butoxide thereto, and react at 100 °C for 15 h. After the reaction is completed, add 1 kg of water to quench the reaction under ice bath, remove the solvent by reduced pressure distillation, wash the obtained residue with water 5 times, and dry it to obtain Compound 1;

[0098] 2) Add 0.1 kg of Compound 1 prepared in step 1) to 0.9 kg of methanol, then add 0.08 kg of potassium hydroxide, and react at 45 °C for 6.5 h. After the reaction is completed, remove the solvent by reduced pressure distillation, wash the obtained residue with water 5 times, and dry it to obtain the terminal carboxyl furan derivative.

[0099] Preparation of polyvinyl acetate resin particles modified with surface furan:

[0100] Add 0.1 kg of surface hydroxylated polyvinyl acetate resin particles and 0.08 kg of terminal carboxyl furan derivative to 1.4 kg of acetonitrile, then add 0.08 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.017 kg of 4-dimethylaminopyridine thereto, stir and mix evenly, heat to 70 °C and react for 15 h. After the reaction is completed, remove the organic solvent by reduced pressure distillation, wash the obtained residue with acetonitrile and water 5 times respectively, and dry it to obtain the polyvinyl acetate resin particles modified with surface furan.

[0101] Preparation of terminal carboxyl maleimide derivative:

[0102] (1) Add 0.1 kg of N-hydroxyethyl maleimide and 0.14 kg of methyl 3-bromopropionate to 1.4 kg of dimethyl sulfoxide. After stirring and dissolving, add 0.14 kg of potassium tert-butoxide thereto, and react at 100 °C for 14 h. After the reaction is completed, add 0.75 kg of water to quench the reaction under ice bath, remove the solvent by reduced pressure distillation, wash the obtained residue with water 5 times, and dry it to obtain Compound 2;

[0103] (2) Add 0.1 kg of Compound 2 prepared in step (1) to 0.9 kg of methanol, then add 0.09 kg of sodium hydroxide, and react at 45 °C for 6.5 h. After the reaction is completed, remove the solvent by reduced pressure distillation, wash the obtained residue with water 5 times, and dry it to obtain the terminal carboxyl maleimide derivative.

[0104] Preparation of surface maleimide-modified polyvinyl acetate resin particles:

[0105] Add 0.1 kg of surface-hydroxylated polyvinyl acetate resin particles and 0.09 kg of carboxyl-terminated maleimide derivative into 1.4 kg of ethyl acetate, then add 0.07 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.014 kg of 4-dimethylaminopyridine thereto, stir and mix evenly, heat to 70 °C and react for 15 h. After the reaction is completed, remove the organic solvent by vacuum distillation. The obtained residue is washed 5 times with ethyl acetate and water respectively, and then dried to obtain surface maleimide-modified polyvinyl acetate resin particles.

[0106] Preparation of polyvinyl acetate resin-modified polyurethane dispersion:

[0107] Add 0.1 kg of surface furan-modified polyvinyl acetate resin particles, 0.12 kg of surface maleimide-modified polyvinyl acetate resin particles and 1.8 kg of polyurethane into 4 kg of acetone, heat to 65 °C, and carry out a mixed reaction for 30 h. Then carry out suction filtration to obtain polyvinyl acetate resin-modified polyurethane dispersion.

[0108] Example 5

[0109] Preparation of surface-hydroxylated polyvinyl acetate resin particles:

[0110] Add 0.1 kg of polyvinyl acetate resin into a mixed solvent of 1 kg of tetrahydrofuran and ethanol, then add 0.15 kg of sodium hydroxide thereto, react at 50 °C for 24 h. After the reaction is completed, remove the solvent by vacuum distillation. The obtained residue is washed 5 times with water, and then added into a mixed solution of 1 kg of chloroform and water to obtain a reaction solution. Then, nitrogen is introduced into the reaction solution at a rate of 5 L / min, and the reaction solution is stirred at 50 r / min. After the solvent has evaporated completely, surface-hydroxylated polyvinyl acetate resin particles are obtained.

[0111] The mass ratio of tetrahydrofuran to ethanol in the mixed solvent of tetrahydrofuran and ethanol is 1:2.

[0112] The mass ratio of chloroform to water in the mixed solution of chloroform and water is 5:0.1.

[0113] Preparation of carboxyl-terminated furan derivative:

[0114] 1) Add 0.1 kg of methyl 3-bromopropionate and 0.1 kg of furfuryl alcohol to 1 kg of dimethyl sulfoxide. After stirring and dissolving, add 0.2 kg of potassium hydride thereto, and react at 110 °C for 12 h. After the reaction is completed, add 1 kg of water to quench the reaction under an ice bath, and remove the solvent by distillation under reduced pressure. The obtained residue is washed with water 5 times and dried to obtain Compound 1;

[0115] 2) Add 0.1 kg of Compound 1 prepared in step 1) to 1 kg of ethanol, and then add 0.1 kg of sodium hydroxide. React at 50 °C for 6 h. After the reaction is completed, remove the solvent by distillation under reduced pressure. The obtained residue is washed with water 5 times and dried to obtain a terminal carboxyl furan derivative.

[0116] Preparation of polyvinyl acetate resin particles modified with surface furan:

[0117] Add 0.1 kg of surface-hydroxylated polyvinyl acetate resin particles and 0.1 kg of terminal carboxyl furan derivative to 1.5 kg of acetonitrile, and then add 0.1 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.02 kg of 4-dimethylaminopyridine thereto. Stir and mix evenly, heat to 80 °C and react for 12 h. After the reaction is completed, remove the organic solvent by distillation under reduced pressure. The obtained residue is washed with acetonitrile and water 5 times respectively and dried to obtain polyvinyl acetate resin particles modified with surface furan.

[0118] Preparation of terminal carboxyl maleimide derivative:

[0119] (1) Add 0.1 kg of N-hydroxyethyl maleimide and 0.15 kg of methyl 3-bromopropionate to 1.5 kg of dimethyl sulfoxide. After stirring and dissolving, add 0.15 kg of sodium tert-butoxide, and react at 110 °C for 12 h. After the reaction is completed, add 0.8 kg of water to quench the reaction under an ice bath, and remove the solvent by distillation under reduced pressure. The obtained residue is washed with water 5 times and dried to obtain Compound 2;

[0120] (2) Add 0.1 kg of Compound 2 prepared in step (1) to 1 kg of methanol, and then add 0.1 kg of sodium hydroxide. React at 50 °C for 6 h. After the reaction is completed, remove the solvent by distillation under reduced pressure. The obtained residue is washed with water 5 times and dried to obtain a terminal carboxyl maleimide derivative.

[0121] Preparation of polyvinyl acetate resin particles modified with surface maleimide:

[0122] Add 0.1 kg of polyvinyl acetate resin particles with surface hydroxylation treatment and 0.12 kg of carboxyl-terminated maleimide derivative into 1.5 kg of ethyl acetate. Then add 0.08 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.016 kg of 4-dimethylaminopyridine thereto, stir and mix evenly, heat to 80 °C and react for 12 h. After the reaction is completed, remove the organic solvent by vacuum distillation. Wash the obtained residue 5 times with ethyl acetate and water respectively, and dry it to obtain polyvinyl acetate resin particles with surface maleimide modification.

[0123] Preparation of polyvinyl acetate resin-modified polyurethane dispersion:

[0124] Add 0.1 kg of polyvinyl acetate resin particles with surface furan modification, 0.12 kg of polyvinyl acetate resin particles with surface maleimide modification and 2 kg of polyurethane into 5 kg of tetrahydrofuran, heat to 70 °C, and carry out a mixing reaction for 24 h. Then carry out suction filtration to obtain polyvinyl acetate resin-modified polyurethane dispersion.

[0125] Carry out performance tests on the polyvinyl acetate resin-modified polyurethane dispersions prepared in Examples 1 to 5 respectively. Among them, the tensile strength and elongation are tested according to the method in ASTM D412, and the comparative example is unmodified polyurethane. It can be seen from the results in Table 1 that the polyvinyl acetate resin-modified polyurethane dispersion prepared by the present invention has a greater elongation and tensile strength compared with the comparative example, and has excellent mechanical properties.

[0126] Table 1 Mechanical properties of the prepared materials

[0127] Item Elongation at break (%) Tensile strength (MPa) Example 1 432 68.3 Example 2 449 71.2 Example 3 461 73.7 Example 4 454 72.4 Example 5 440 70.5 Comparative example 255 44.9

[0128] Heat the polyvinyl acetate resin-modified polyurethane dispersion prepared in Example 3 to 130 °C to cause a decomposition cross-linking reaction. Then quickly cool the polyvinyl acetate resin-modified polyurethane dispersion to room temperature and place it at 60 °C for a reaction of 36 h to obtain a reprocessed polyvinyl acetate resin-modified polyurethane dispersion. Cycle 3 times in this way. Carry out mechanical property tests on the obtained reprocessed polyvinyl acetate resin-modified polyurethane dispersions respectively, and the test results are shown in Table 2. It can be seen from the results in Table 2 that after multiple cycles of D-A reaction, the mechanical properties of the polyvinyl acetate resin-modified polyurethane dispersion prepared by the present invention basically remain unchanged, the processability is good, and it has broad application prospects.

[0129] Table 2 Reprocessing performance test results

[0130] Times Elongation at break (%) Tensile strength (MPa) 0 461 73.7 1 457 72.5 2 453 72.1 3 451 72.0

[0131] Although the specific implementation manners of the present invention are described above, they do not limit the protection scope of the present invention. Based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A polyvinyl acetate resin modified polyurethane dispersion, characterized in that: The invention is composed of the following raw materials in parts by weight: 1 part of polyvinyl acetate resin particles modified with furan on the surface, 1-1.2 parts of polyvinyl acetate resin particles modified with maleimide on the surface and 10-20 parts of polyurethane; The polyvinyl acetate resin modified polyurethane dispersion is prepared by respectively modifying the surface of polyvinyl acetate resin particles subjected to surface hydroxylation with terminal carboxyl furan derivatives and terminal carboxyl maleimide derivatives, and then doping the surface furan-modified polyvinyl acetate resin particles and the surface maleimide-modified polyvinyl acetate resin particles into polyurethane.

2. The polyvinyl acetate resin modified polyurethane dispersion according to claim 1, characterized in that: The surface furan-modified polyvinyl acetate resin particles are prepared according to the following method: by weight, 1 part of surface hydroxylated polyvinyl acetate resin particles and 0.1-1 part of terminal carboxyl furan derivatives are added to 10-15 parts of organic solvent 1, and then 0.1-1 part of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.02-0.2 part of 4-dimethylaminopyridine are added thereto, and the mixture is stirred and mixed uniformly, and the mixture is heated to 25-80° C. to react for 12-24 hours. After the reaction is completed, the organic solvent is removed by reduced pressure distillation, and the residue is washed with organic solvent 1 and water for 3-5 times, respectively, and dried to obtain surface furan-modified polyvinyl acetate resin particles; The organic solvent 1 is dichloromethane, chloroform, acetonitrile or ethyl acetate.

3. The polyvinyl acetate resin modified polyurethane dispersion according to claim 2, characterized in that: The method for preparing the carboxyl-terminated furan derivative comprises the following steps: 1) In parts by weight, 1 part of methyl 3-bromopropionate and 0.6-1 part of furan methanol are added to 5-10 parts of organic solvent 2, stirred to dissolve, and then 0.7-2 parts of base 1 are added thereto, and the mixture is reacted at 50-110° C. for 12-24 hours. After the reaction is completed, 8-10 parts of water are added under ice bath to quench the reaction, and the solvent is removed by distillation under reduced pressure. The residue is washed with water 3-5 times and dried to obtain compound 1; 2) Add 1 part of the compound 1 obtained in step 1) to 5-10 parts of an alcohol solvent, and then add 0.3-1 part of a base 2, and react at 25-50° C. for 6-8 hours. After the reaction is completed, remove the solvent by distillation under reduced pressure, wash the residue with water 3-5 times, and dry it to obtain a terminal carboxyl furan derivative.

4. The polyvinyl acetate resin modified polyurethane dispersion according to claim 3, characterized in that: The organic solvent 2 in step 1) is dimethyl sulfoxide or dimethylformamide; the base 1 in step 1) is sodium hydride, potassium hydride, sodium tert-butoxide or potassium tert-butoxide; the alcohol solvent in step 2) is methanol or ethanol; the base 2 in step 2) is sodium hydroxide or potassium hydroxide.

5. The polyvinyl acetate resin modified polyurethane dispersion according to claim 4, characterized in that: The preparation method of the surface hydroxylated polyvinyl acetate resin particles is as follows: In parts by weight, 1 part of polyvinyl acetate resin is added to a mixed solvent of 5-10 parts of an organic solvent 3 and an alcohol solvent, and then 0.5-1.5 parts of a base 2 is added thereto, and the mixture is reacted at 25-50° C. for 12-24 hours. After the reaction is completed, the solvent is removed by reduced pressure distillation, and the obtained residue is washed with water for 3-5 times, and then added to a mixed solution of 5-10 parts of chloroform and water to obtain a reaction solution, and then an inert gas is introduced into the reaction solution at a rate of 1-5 L / min, and the reaction solution is stirred at 5-50 r / min. After the solvent is evaporated, polyvinyl acetate resin particles with surface hydroxylation treatment are obtained.

6. The polyvinyl acetate resin modified polyurethane dispersion according to claim 5, characterized in that: The organic solvent 3 is tetrahydrofuran, chloroform, dichloromethane or acetone; the mass ratio of the organic solvent 3 to the alcohol solvent in the mixed solvent of the organic solvent 3 and the alcohol solvent is 1:1-2.

7. The polyvinyl acetate resin modified polyurethane dispersion according to claim 5, characterized in that: The mass ratio of chloroform to water in the mixed solution of chloroform and water is 1-5:0.1; and the inert gas is nitrogen or argon.

8. The polyvinyl acetate resin modified polyurethane dispersion according to claim 5, characterized in that: The surface maleimide-modified polyvinyl acetate resin particles are prepared according to the following method: by weight, 1 part of surface hydroxylated polyvinyl acetate resin particles and 0.1-1.2 parts of terminal carboxyl maleimide derivatives are added to 10-15 parts of organic solvent 1, and then 0.08-0.8 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 0.015-0.16 parts of 4-dimethylaminopyridine are added thereto, and the mixture is stirred and mixed uniformly, and the mixture is heated to 25-80° C. to react for 12-24 hours. After the reaction is completed, the organic solvent is removed by reduced pressure distillation, and the residue is washed with organic solvent 1 and water for 3-5 times respectively, and dried to obtain surface maleimide-modified polyvinyl acetate resin particles.

9. The polyvinyl acetate resin modified polyurethane dispersion according to claim 8, characterized in that: The preparation method of the carboxyl-terminated maleimide derivative comprises the following steps: (1) In parts by weight, 1 part of N-hydroxyethylmaleimide and 1.2-1.5 parts of methyl 3-bromopropionate are added to 8-15 parts of organic solvent 2, stirred to dissolve, and then 0.8-1.5 parts of base 1 are added. The mixture is reacted at 50-110° C. for 12-24 hours. After the reaction is completed, 5-8 parts of water are added under ice bath to quench the reaction. The solvent is removed by distillation under reduced pressure, and the residue is washed with water 3-5 times and dried to obtain compound 2; (2) Add 1 part of the compound 2 prepared in step (1) to 5-10 parts of an alcohol solvent, and then add 0.25-1 part of a base 2, and react at 25-50° C. for 6-8 hours. After the reaction is completed, remove the solvent by distillation under reduced pressure, wash the residue with water 3-5 times, and dry to obtain a terminal carboxyl maleimide derivative.

10. The method for preparing the polyvinyl acetate resin modified polyurethane dispersion according to claim 1, characterized in that: The following steps are involved: In parts by weight, 1 part of polyvinyl acetate resin particles modified with furan on the surface, 1-1.2 parts of polyvinyl acetate resin particles modified with maleimide on the surface, and 10-20 parts of polyurethane are added to 10-50 parts of organic solvent 3, heated to 50-70° C., mixed and reacted for 24-48 hours, and filtered to obtain a polyvinyl acetate resin modified polyurethane dispersion; The organic solvent 3 is tetrahydrofuran, chloroform, dichloromethane or acetone.

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