Polycaprolactone polyol modified acrylic emulsion as well as preparation method and coating thereof

Abstract

The invention discloses a polycaprolactone polyol modified acrylic emulsion, a preparation method thereof and a coating, and relates to the field of acrylic emulsion synthesis and coating research and development, the preparation method comprises the steps of preparing a branched monomer, preparing polycaprolactone polyol modified acrylic resin, and preparing the polycaprolactone polyol modified acrylic emulsion. According to the preparation method, the problem that the water resistance and medium resistance of resin are reduced due to direct introduction of polycaprolactone is solved, the prepared polycaprolactone polyol modified acrylic emulsion has a branched structure, the branched center is a polycaprolactone polyol unit, and the unit contains a large number of methylene groups and polyester bonds, so that the water resistance and medium resistance of the resin are improved. The emulsion can reduce the hydrogen-bond interaction between molecules, so that when the emulsion is used for coating preparation, the flexibility and impact resistance of a coating can be improved, the obtained coating has high elasticity and good wear resistance, and due to the fact that a main esterification group is located in a branched center, the stability of the coating is improved. Therefore, the coating prepared from the emulsion has good hydrolysis resistance and chemical resistance.

Description

Technical Field

[0001] The invention relates to the field of acrylic emulsion synthesis and coating research and development, in particular to a polycaprolactone polyol modified acrylic emulsion and a preparation method and coating thereof. Background Art

[0002] Acrylic paints are widely used in engineering machinery, highway bridges, ships, steel structures, wind power equipment, instrumentation and other fields due to their good gloss and color retention, bright and full paint film appearance, excellent weather resistance and chemical resistance. However, acrylic paints have relatively poor flexibility, impact resistance and wear resistance, which affects the comprehensive performance of the coating and shortens the service life of the coating.

[0003] ε-caprolactone is a cyclic compound with high reactivity. After ring-opening polymerization, it becomes a chain molecule. The molecular chain contains a large number of methylene and polyester bonds, which can reduce the hydrogen bonding effect between molecules. Therefore, mixing polycaprolactone in the polymer or introducing polycaprolactone into the polymer structure can make it have good deformability and flexibility.

[0004] People have found that by mixing polycaprolactone polyols with other resins, the flexibility, impact resistance and wear resistance of the prepared coatings will be significantly improved. Therefore, a series of commercialized aliphatic polyester polyol products including polycaprolactone polyols have appeared on the market for mixing with other resins. The physical mixing method is relatively simple to operate and has low cost, but the acid and alkali resistance of polyester is relatively poor; and when the properties of the mixed resins are greatly different, the compatibility is poor, the stability is not high, and separation is easy to occur. For example, when polycaprolactone polyols are mixed with acrylic resins, they have good compatibility with hydroxy acrylic resins, but poor compatibility with ordinary acrylic resins. This also limits the mixing and use of polycaprolactone series products to a certain extent.

[0005] Introducing polycaprolactone into the polymer structure can avoid the problem of resin incompatibility. Liu Jinchun et al. reported on the study of preparing mixed polyurethane with polycaprolactone polyol; Shu Jinbing et al. reported on the one-pot preparation of polycaprolactone polyol-modified acrylic dispersion and its application; Patent CN 118184899 A reported a polycaprolactone-modified fluorosilicone acrylic resin and its preparation and application. Studies have found that the introduction of polycaprolactone can improve the flexibility, impact resistance and wear resistance of the coating. However, these methods directly introduce polycaprolactone into the polymer main chain through amide bonds or ester bonds. The ester bond has poor media resistance, which will affect the media resistance of the coating to a certain extent. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem that the direct introduction of polycaprolactone will cause the water resistance and medium resistance of the resin to decrease, and to provide a polycaprolactone polyol-modified acrylic emulsion and a preparation method and a coating. The polycaprolactone polyol-modified acrylic emulsion synthesized by the present invention can not only improve the flexibility, impact resistance and wear resistance of the coating; and because the emulsion has a core-shell structure and the main esterification group is at the branching center, the coating prepared using the emulsion has good hydrolysis resistance and chemical resistance.

[0007] The present invention provides a method for preparing a polycaprolactone polyol-modified acrylic emulsion, comprising the following steps:

[0008] a. Preparation of branched monomers: firstly preparing polycaprolactone polyol with polyol and cyclohexanolactone, and esterifying polycaprolactone polyol with carboxylic acid to obtain branched monomers;

[0009] b. Preparing a polycaprolactone polyol-modified acrylic resin: obtaining a polycaprolactone polyol-modified acrylic resin by free radical polymerization of the branched monomer prepared in step a and an acrylic acid monomer;

[0010] c. Preparation of polycaprolactone polyol-modified acrylic emulsion: extracting the organic solvent from the polycaprolactone polyol-modified acrylic resin prepared in step b, adding corresponding additives, and stirring at high speed to obtain the polycaprolactone polyol-modified acrylic emulsion.

[0011] Furthermore, in step a, the process of preparing the branched monomer is specifically as follows: first weigh the polyol and polycaprolactone and add them into a reaction bottle, then add an appropriate amount of xylene solvent and a small amount of zinc oxide, slowly heat up to 130°C, reflux the solvent for water separation, keep warm for 1-2 hours, test the acid value to be qualified, add carboxylic acid, continue to keep warm for 1 hour, reflux the solvent for water separation, test the acid value to be qualified, and cool down to obtain the branched monomer.

[0012] Preferably, the polyol is a mixture of glycerol and pentaerythritol, and the carboxylic acid is a mixture of acrylic acid and crotonic acid.

[0013] More preferably, the raw materials used in the preparation of the branched monomer are calculated by mass fraction as follows: 2.4-3.9% of glycerol, 4.9-8.7% of pentaerythritol, 57.7-79.8% of cyclohexanolactone, 6.3-12.8% of acrylic acid and 8.7-21.1% of crotonic acid, and the sum of the mass fractions of the above raw materials is 100%.

[0014] Furthermore, in step b, the process for preparing the polycaprolactone polyol-modified acrylic resin is specifically as follows: first, the branched monomer and part of the solvent are added to the reaction bottle, the temperature is raised to 135-140°C, and then the initiator, acrylic monomer and the remaining solvent are prepared into a mixed solution, 75% of the mixed solution is added to the dropping funnel and dripped into the reaction bottle, and the dripping is completed within 3-4 hours, and the mixture is kept warm for 2 hours, and the remaining mixed solution is added and dripped within 0.5-1 hour. After keeping warm for 1 hour, sampling is performed to detect the viscosity and non-volatile content of the polymerization reaction system. After the viscosity is qualified, the temperature is lowered, the solvent is extracted, and emulsification is performed.

[0015] Preferably, the acrylic monomer is a mixture of methyl methacrylate, hydroxypropyl acrylate, acrylonitrile, isobutyl methacrylate, styrene and crotonic acid.

[0016] More preferably, the raw materials used in the preparation of the polycaprolactone polyol-modified acrylic resin are calculated by mass fraction as follows: 1.5-2.5% of branched monomers, 22-27% of methyl methacrylate, 10.5-14% of hydroxypropyl acrylate, 3-5% of acrylonitrile, 11-15% of isobutyl methacrylate, 35-45% of styrene, and 4-6% of crotonic acid, and the sum of the mass fractions of the above raw materials is 100%.

[0017] Preferably, the initiator is tert-butyl hydroperoxide and benzoyl peroxide, the amount of tert-butyl hydroperoxide is 0.02% of the total mass of the branched monomer and the acrylic acid monomer, and the amount of benzoyl peroxide is 0.2% of the total mass of the branched monomer and the acrylic acid monomer.

[0018] Furthermore, in step c, the process of preparing the polycaprolactone polyol-modified acrylic emulsion is specifically as follows: a multifunctional amine neutralizer, an emulsifier, a cosolvent and deionized water are added to the polycaprolactone polyol-modified acrylic resin from which the organic solvent has been extracted, and the polycaprolactone polyol-modified acrylic emulsion is obtained by high-speed stirring.

[0019] Preferably, the multifunctional amine neutralizer is APM-95, the emulsifier is a nonionic emulsifier, and the cosolvent is ethylene glycol monobutyl ether.

[0020] More preferably, the raw materials used in preparing the polycaprolactone polyol-modified acrylic emulsion are calculated by mass fraction as follows: 55-65% polycaprolactone polyol-modified acrylic resin, 1.5-2.2% multifunctional amine neutralizer, 2.8-3.5% emulsifier, 4-6% cosolvent and 23-36.7% deionized water.

[0021] The invention also provides a polycaprolactone polyol-modified acrylic emulsion, which is prepared by the above-mentioned preparation method.

[0022] The present invention also provides a coating comprising the polycaprolactone polyol-modified acrylic emulsion.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The preparation method of the polycaprolactone polyol-modified acrylic emulsion of the present invention overcomes the problem of reduced water resistance and medium resistance of the resin caused by directly introducing polycaprolactone. The prepared polycaprolactone polyol-modified acrylic emulsion has a branched structure, and the branching center is a polycaprolactone polyol unit. A large number of methylene and polyester bonds contained in the unit can reduce the hydrogen bonding effect between molecules. Therefore, the emulsion is used in the preparation of coatings to help improve the flexibility and impact resistance of the coating. The obtained coating has high elasticity and good wear resistance. Moreover, since the main esterification group is in the branching center, the coating prepared using the emulsion has good hydrolysis resistance and chemical resistance.

[0025] 2. The polycaprolactone polyol-modified acrylic emulsion provided by the present invention uses water as a solvent, and the coating prepared therefrom is an environmentally friendly material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The particle size distribution diagram of the polycaprolactone polyol-modified acrylic emulsion prepared in Example 1;

[0027] Figure 2 This is a particle size distribution diagram of the polycaprolactone polyol-modified acrylic emulsion prepared in Example 2;

[0028] Figure 3 The particle size distribution diagram of the polycaprolactone polyol-modified acrylic emulsion prepared in Example 3;

[0029] Figure 4 Particle size distribution diagram of the polycaprolactone polyol-modified acrylic emulsion prepared in Example 4. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be described clearly and completely in conjunction with the embodiments below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] Weigh 2.4g of propylene glycol, 7.2g of pentaerythritol and 66.5g of cyclohexyllactone, add to a reaction bottle, then add 10mL of xylene solvent and 0.2g of zinc oxide, slowly heat to 130°C, reflux the solvent to separate water, keep warm for 1-2h, and after the acid value is qualified, add 6.3g of acrylic acid and 17.6g of crotonic acid, continue to keep warm for 1h, reflux the solvent to separate water, and cool down after the acid value is qualified to obtain a branched monomer.

[0033] Weigh 2.5g of the obtained branched monomer, measure 10mL of xylene, add it to a reaction bottle, and raise the temperature to 135-140°C; weigh 27g of methyl methacrylate, 11.5g of hydroxypropyl acrylate, 5g of acrylonitrile, 15g of isobutyl methacrylate, 35g of styrene, 4g of crotonic acid, 0.02g of tert-butyl hydroperoxide and 0.2g of benzoyl peroxide, add 5mL of xylene, mix evenly to obtain a mixed solution; add 75% of the above mixed solution into a dropping funnel, drip it in 3-4h, keep it warm for 2h, add the remaining mixed solution, drip it in 0.5-1h, keep it warm for 1h, and obtain a polycaprolactone polyol-modified acrylic resin; take a sample, detect the viscosity and non-volatile content of the polymerization reaction system, and after the viscosity is qualified, cool down, extract the solvent, and wait for emulsification.

[0034] 55 g of the polycaprolactone polyol-modified acrylic resin was weighed and added into a reaction bottle, and then 1.5 g of a multifunctional amine neutralizer, 2.8 g of an emulsifier, 4 g of a cosolvent and 36.7 g of deionized water were added in sequence, and stirred at high speed for 0.5-1 h to obtain a polycaprolactone polyol-modified acrylic emulsion.

[0035] The particle size distribution of the polycaprolactone polyol-modified acrylic emulsion prepared in this example is shown in FIG. Figure 1 The particle size characteristic parameters are shown in Table 1.

[0036] Table 1 Particle size characteristic parameters of polycaprolactone polyol modified acrylic emulsion of Example 1

[0037]

[0038] Example 2

[0039] Weigh 2.9g of propylene glycol, 8.6g of pentaerythritol and 79.8g of cyclohexyllactone, add to a reaction bottle, then add 10mL of xylene solvent and 0.2g of zinc oxide, slowly heat to 130°C, reflux the solvent to separate water, keep warm for 1-2h, and after the acid value is qualified, add 7.6g of acrylic acid and 21.1g of crotonic acid, continue to keep warm for 1h, reflux the solvent to separate water, and cool down after the acid value is qualified to obtain a branched monomer.

[0040] Weigh 1.5 g of the obtained branched monomer, measure 10 mL of xylene, add them into a reaction bottle, and raise the temperature to 135-140° C.; weigh 23 g of methyl methacrylate, 10.5 g of hydroxypropyl acrylate, 3 g of acrylonitrile, 11 g of isobutyl methacrylate, 45 g of styrene, 6 g of crotonic acid, 0.02 g of tert-butyl hydroperoxide and 0.2 g of benzoyl peroxide, add 5 mL of xylene, mix evenly to obtain a mixed solution, add 75% of the mixed solution into a dropping funnel, drip it in 3-4 hours, keep it warm for 2 hours, add the remaining mixed solution, drip it in 0.5-1 hour, keep it warm for 1 hour to obtain a polycaprolactone polyol-modified acrylic resin; take a sample, detect the viscosity and non-volatile content of the polymerization reaction system, and after the viscosity is qualified, cool down, extract the solvent, and wait for emulsification.

[0041] 65 g of the weighed polycaprolactone polyol-modified acrylic resin was added to a reaction bottle, and then 2.5 g of a multifunctional amine neutralizer, 3.5 g of an emulsifier, 6 g of a cosolvent and 23 g of deionized water were added in sequence, and the mixture was stirred at high speed for 0.5-1 h to obtain a polycaprolactone polyol-modified acrylic emulsion.

[0042] The particle size distribution of the polycaprolactone polyol-modified acrylic emulsion prepared in this example is shown in FIG. Figure 2 The particle size characteristic parameters are shown in Table 2.

[0043] Table 2 Particle size characteristic parameters of polycaprolactone polyol modified acrylic emulsion of Example 2

[0044]

[0045] Example 3

[0046] Weigh 3.9g of propylene glycol, 5.7g of pentaerythritol and 67.4g of cyclohexyllactone, add to a reaction bottle, then add 10mL of xylene solvent and 0.2g of zinc oxide, slowly heat to 130°C, reflux the solvent to separate water, keep warm for 1-2h, and after the acid value is qualified, add 12.8g of acrylic acid and 110.2g of crotonic acid, continue to keep warm for 1h, reflux the solvent to separate water, and cool down after the acid value is qualified to obtain a branched monomer.

[0047] Weigh 2.2g of the obtained branched monomer, measure 10mL of xylene, add it to a reaction bottle, and raise the temperature to 135-140°C; weigh 26g of methyl methacrylate, 12.8g of hydroxypropyl acrylate, 4g of acrylonitrile, 13g of isobutyl methacrylate, 37g of styrene, 5g of crotonic acid, 0.02g of tert-butyl hydroperoxide and 0.2g of benzoyl peroxide, add 5mL of xylene, mix evenly to obtain a mixed solution, add 75% of the mixed solution into a dropping funnel, drip it in 3-4h, keep it warm for 2h, add the remaining mixed solution, drip it in 0.5-1h, keep it warm for 1h to obtain a polycaprolactone polyol-modified acrylic resin; take a sample, detect the viscosity and non-volatile content of the polymerization reaction system, and after the viscosity is qualified, cool down, extract the solvent, and wait for emulsification.

[0048] 58 g of the weighed polycaprolactone polyol-modified acrylic resin was added to a reaction bottle, and then 2 g of a multifunctional amine neutralizer, 3 g of an emulsifier, 4 g of a cosolvent and 33 g of deionized water were added in sequence, and the mixture was stirred at high speed for 0.5-1 h to obtain a polycaprolactone polyol-modified acrylic emulsion.

[0049] The particle size distribution of the polycaprolactone polyol-modified acrylic emulsion prepared in this example is shown in FIG. Figure 3 The particle size characteristic parameters are shown in Table 3.

[0050] Table 3 Particle size characteristic parameters of polycaprolactone polyol modified acrylic emulsion of Example 3

[0051]

[0052] Example 4

[0053] Weigh 3.3g of propylene glycol, 4.9g of pentaerythritol and 57.7g of cyclohexyllactone, add to a reaction bottle, then add 10mL of xylene solvent and 0.2g of zinc oxide, slowly heat to 130°C, reflux the solvent to separate water, keep warm for 1-2h, and after the acid value is tested to be qualified, add 10.9g of acrylic acid and 8.7g of crotonic acid, continue to keep warm for 1h, reflux the solvent to separate water, and cool down after the acid value is tested to be qualified to obtain a branched monomer.

[0054] Weigh 2g of the obtained branched monomer, measure 10mL of xylene, add them into a reaction bottle, and raise the temperature to 135-140°C; weigh 22g of methyl methacrylate, 14g of hydroxypropyl acrylate, 3g of acrylonitrile, 14g of isobutyl methacrylate, 40g of styrene, 5g of crotonic acid, 0.02g of tert-butyl hydroperoxide and 0.2g of benzoyl peroxide, add 5mL of xylene, mix evenly to obtain a mixed solution; add 75% of the mixed solution into a dropping funnel, drip it in 3-4h, keep it warm for 2h, add the remaining mixed solution, drip it in 0.5-1h, keep it warm for 1h to obtain a polycaprolactone polyol-modified acrylic resin; take a sample, detect the viscosity and non-volatile content of the polymerization reaction system, and after the viscosity is qualified, cool down, extract the solvent, and wait for emulsification.

[0055] 60 g of the polycaprolactone polyol-modified acrylic resin was weighed and added into a reaction bottle, and then 2.2 g of a multifunctional amine neutralizer, 3.2 g of an emulsifier, 5 g of a cosolvent and 29.6 g of deionized water were added in sequence, and the mixture was stirred at high speed for 0.5-1 h to obtain a polycaprolactone polyol-modified acrylic emulsion.

[0056] The particle size distribution of the polycaprolactone polyol-modified acrylic emulsion prepared in this example is shown in FIG. Figure 4 The particle size characteristic parameters are shown in Table 4.

[0057] Table 4 Particle size characteristic parameters of polycaprolactone polyol modified acrylic emulsion of Example 4

[0058]

[0059] Example 5

[0060] The polycaprolactone polyol-modified acrylic emulsion prepared in Examples 1-4 was used to prepare coatings according to the following formula to obtain four coating samples 1#-4#.

[0061]

[0062]

[0063] The performance of the four coating samples 1#-4# was tested, and the test results are shown in Table 5.

[0064] Table 5 Performance of four coating samples 1#-4#

[0065]

[0066]

[0067] The test data in Table 5 show that the emulsions obtained in Examples 1-4 can be used in the preparation of water-based coatings, and the obtained coatings are highly elastic, medium-resistant, and wear-resistant coatings with good flexibility, impact resistance, medium resistance, and wear resistance.

Claims

1. A method for preparing a polycaprolactone polyol-modified acrylic emulsion, characterized in that: The steps include: a. Preparation of branched monomers: firstly preparing polycaprolactone polyol with polyol and cyclohexanolactone, and esterifying polycaprolactone polyol with carboxylic acid to obtain branched monomers; b. Preparing a polycaprolactone polyol-modified acrylic resin: obtaining a polycaprolactone polyol-modified acrylic resin by free radical polymerization of the branched monomer prepared in step a and an acrylic acid monomer; c. Preparation of polycaprolactone polyol-modified acrylic emulsion: extracting the organic solvent from the polycaprolactone polyol-modified acrylic resin prepared in step b, adding corresponding additives, and stirring at high speed to obtain the polycaprolactone polyol-modified acrylic emulsion.

2. The method for preparing a polycaprolactone polyol-modified acrylic emulsion according to claim 1, wherein In step a, the process of preparing the branched monomer is specifically as follows: first weigh the polyol and polycaprolactone and add them into a reaction bottle, then add an appropriate amount of xylene solvent and a small amount of zinc oxide, slowly heat to 130°C, reflux the solvent for water separation, keep warm for 1-2 hours, test the acid value after it is qualified, add carboxylic acid, continue to keep warm for 1 hour, reflux the solvent for water separation, test the acid value after it is qualified, and cool down to obtain a branched monomer.

3. The method for preparing a polycaprolactone polyol-modified acrylic emulsion according to claim 2, wherein: The raw materials used in preparing the branched monomer are calculated by mass fraction as follows: 2.4-3.9% of propylene glycol, 4.9-8.7% of pentaerythritol, 57.7-79.8% of cyclohexanolactone, 6.3-12.8% of acrylic acid and 8.7-21.1% of crotonic acid, and the sum of the mass fractions of the above raw materials is 100%.

4. The method for preparing a polycaprolactone polyol-modified acrylic emulsion according to claim 1, wherein: In step b, the process of preparing the polycaprolactone polyol-modified acrylic resin is specifically as follows: first, the branched monomer and part of the solvent are added to the reaction bottle, the temperature is raised to 135-140°C, and then the initiator, acrylic monomer and the remaining solvent are prepared into a mixed solution, 75% of the mixed solution is added to the dropping funnel and dripped into the reaction bottle, and the dripping is completed in 3-4 hours, and the mixture is kept warm for 2 hours, and the remaining mixed solution is added, and the dripping is completed in 0.5-1 hour. After keeping warm for 1 hour, sampling is performed to detect the viscosity and non-volatile content of the polymerization reaction system. After the viscosity is qualified, the temperature is lowered, the solvent is extracted, and emulsification is performed.

5. The method for preparing the polycaprolactone polyol-modified acrylic emulsion according to claim 4, characterized in that: The raw materials used in preparing the polycaprolactone polyol modified acrylic resin are calculated by mass fraction as follows: 1.5-2.5% of branched monomer, 22-27% of methyl methacrylate, 10.5-14% of hydroxypropyl acrylate, 3-5% of acrylonitrile, 11-15% of isobutyl methacrylate, 35-45% of styrene, and 4-6% of crotonic acid, and the sum of the mass fractions of the above raw materials is 100%.

6. The method for preparing the polycaprolactone polyol-modified acrylic emulsion according to claim 4, characterized in that: The initiators are tert-butyl hydroperoxide and benzoyl peroxide, the amount of tert-butyl hydroperoxide is 0.02% of the total mass of the branched monomer and the acrylic acid monomer, and the amount of benzoyl peroxide is 0.2% of the total mass of the branched monomer and the acrylic acid monomer.

7. The method for preparing a polycaprolactone polyol-modified acrylic emulsion according to claim 1, wherein: In step c, the process of preparing the polycaprolactone polyol-modified acrylic emulsion is specifically as follows: a multifunctional amine neutralizer, an emulsifier, a cosolvent and deionized water are added to the polycaprolactone polyol-modified acrylic resin from which the organic solvent has been extracted, and the polycaprolactone polyol-modified acrylic emulsion is obtained by high-speed stirring.

8. The method for preparing the polycaprolactone polyol-modified acrylic emulsion according to claim 7, wherein: The raw materials used in preparing the polycaprolactone polyol-modified acrylic emulsion are calculated by mass fraction as follows: 55-65% of polycaprolactone polyol-modified acrylic resin, 1.5-2.2% of multifunctional amine neutralizer, 2.8-3.5% of emulsifier, 4-6% of cosolvent and 23-36.7% of deionized water; the multifunctional amine neutralizer is APM-95, the emulsifier is a nonionic emulsifier, and the cosolvent is ethylene glycol monobutyl ether.

9. A polycaprolactone polyol-modified acrylic emulsion, characterized in that: The polycaprolactone polyol-modified acrylic emulsion is prepared by the preparation method of the polycaprolactone polyol-modified acrylic emulsion according to any one of claims 1 to 8.

10. A coating, characterized in that: A polycaprolactone polyol-modified acrylic emulsion prepared by the preparation method of the polycaprolactone polyol-modified acrylic emulsion according to any one of claims 1 to 8.

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