Hydroxyl acrylic resin as well as preparation method and application thereof

Abstract

The invention provides hydroxy acrylic resin and a preparation method and application thereof.The preparation method comprises the steps that polyester raw materials at least containing trihydric alcohol, dihydric alcohol, cyclic anhydride and long-chain fatty acid are put into a reaction kettle, and the column top temperature of the reaction kettle is controlled to range from 95 DEG C to 110 DEG C; heating the reaction kettle to a first temperature interval of 220-240 DEG C, and keeping the temperature at 215-235 DEG C for 50-70 minutes; cooling to 170-190 DEG C, adding an azeotropic solvent for dehydration, and then heating to 220-235 DEG C in a second temperature interval for continuous reaction; after reacting for 2.5-3.5 hours, sampling and detecting, and controlling the acid value to be 8-15mgKOH / g; and cooling to 130-150 DEG C, adding a diluent to adjust the solid content to 75-85%, finally cooling to 80-100 DEG C, and packaging to obtain the polyester polyol. Synthesizing hydroxyl acrylic resin from polyester polyol to obtain hydroxyl acrylic resin; high solid content, low viscosity and low VOC are taken into consideration, and construction performance and environmental protection indexes are guaranteed by optimizing the process synergy of polyester synthesis and acrylic acid polymerization.

Description

Technical Field

[0001] The present invention relates to the technical field of hydroxyl acrylic resins, and particularly relates to a hydroxyl acrylic resin, a preparation method thereof, and an application thereof. Background Art

[0002] As an important film-forming substance in the coating field, hydroxyl acrylic resin is widely used in automotive, ship, and industrial protective coatings due to its excellent weather resistance, mechanical strength, and high reactivity with isocyanate curing agents. Traditional hydroxyl acrylic resins are mostly prepared by free radical polymerization. However, to meet the environmental protection requirements of high solid content and low viscosity (VOC ≤ 250 g / L), the existing technology faces the following bottlenecks:

[0003] 1. The balance contradiction between resin viscosity and solid content: Conventional acrylic resins increase the solid content by adding branched monomers, but the wide molecular weight distribution leads to a sharp increase in system viscosity, making it difficult to balance the construction performance and environmental protection indicators;

[0004] 2. Process defects of polyester-acrylic composite resins: The existing technology attempts to physically blend polyester polyols and acrylic resins, but poor compatibility easily leads to phase separation, and the uneven distribution of hydroxyl groups in the polyester chain segment results in insufficient curing crosslinking density (salt spray resistance < 500 hours);

[0005] 3. Acid value and storage stability problems: The traditional esterification reaction uses a single dehydration process (such as vacuum dehydration), which easily causes fluctuations in acid value (> 15 mgKOH / g). The residual carboxyl groups accelerate the yellowing of the resin, and the high acid value increases the risk of storage gelation.

[0006] The disclosure of the above background art content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical guidance; without clear evidence indicating that the above content was publicly available before the filing date of this patent application, the above background art should not be used to evaluate the novelty and creativity of this application. Summary of the Invention

[0007] In order to solve the technical problems such as the balance contradiction between resin viscosity and solid content, the process defects of polyester-acrylic composite resins, and acid value and storage stability, the present invention proposes a hydroxyl acrylic resin that takes into account high solid content, low viscosity, and low VOC, a preparation method thereof, and an application thereof. By optimizing the process synergy of polyester synthesis and acrylic polymerization, the limitation that performance and environmental protection are difficult to coexist in the existing technology is broken through, and the construction performance and environmental protection indicators are ensured.

[0008] To achieve the above object, the technical solution of the present invention is as follows:

[0009] On the one hand, the present invention provides a preparation method of a hydroxyl acrylic resin, comprising the following steps:

[0010] S1 synthesizes a polyester polyol, including the following steps:

[0011] S101 Inputs polyester raw materials including at least a triol, a diol, a cyclic anhydride, and a long-chain fatty acid into a reaction kettle, and controls the temperature at the top of the reaction kettle column to be 95-110 °C;

[0012] S102 Raises the temperature of the reaction kettle to a first temperature range of 220-240 °C, and holds the temperature at 215-235 °C for 50-70 minutes;

[0013] S103 Lowers the temperature to 170-190 °C, adds an azeotropic solvent for dehydration, and then raises the temperature to a second temperature range of 220-235 °C for continuous reaction;

[0014] S104 Samples and tests after reacting for 2.5-3.5 hours, and controls the acid value to be 8-15 mgKOH / g;

[0015] S105 Cools to 130-150 °C, adds a diluent to adjust the solid content to 75-85%, and finally cools to 80-100 °C and packages to obtain the polyester polyol;

[0016] S2 Uses the polyester polyol to synthesize a hydroxyl acrylic resin to obtain the hydroxyl acrylic resin.

[0017] The present invention proposes a hydroxyl acrylic resin that takes into account high solid content, low viscosity, and low VOC, and its preparation method and application. By optimizing the process synergy of polyester synthesis and acrylic polymerization, it breaks through the limitation that it is difficult to achieve both performance and environmental protection in the prior art, and ensures the construction performance and environmental protection indicators.

[0018] As a preferred technical solution, the triol includes: trimethylolpropane, the diol includes: neopentyl glycol, the cyclic anhydride includes: hexahydrophthalic anhydride, and the long-chain fatty acid includes: isononanoic acid; the triol and the diol account for 30%-70% of the total mass of the raw materials. Among them, the weight ratio of the triol to the diol is 1:2.2-3.8, the cyclic anhydride and the long-chain fatty acid account for 30%-70% of the total mass of the raw materials. Among them, the weight ratio of the cyclic anhydride to the long-chain fatty acid is 1:1.1-1.6.

[0019] As a preferred technical solution, the azeotropic solvent in step S103 is xylene, and the addition amount is 3%-10% of the total mass of the reaction system, and azeotropic dehydration is carried out through a reflux device, and the heating rate after dehydration is 3-8 °C / min.

[0020] As a preferred technical solution, the diluent in step S105 includes: butyl acetate.

[0021] As a preferred technical solution, in step S2, a hydroxyl acrylic resin is synthesized from a polyester polyol to obtain a hydroxyl acrylic resin, which includes the following steps:

[0022] S201 Put the polyester polyol and propylene glycol methyl ether acetate into a reaction vessel;

[0023] S202 Dropwise add a mixed monomer of styrene monomer, (meth)acrylate monomer and hydroxyl-containing monomer, and a peroxide initiator into the reaction vessel;

[0024] S203 Under a pressurized condition, heat up to 190 - 200 °C, and dropwise add the mixed monomer at a temperature of 190 - 200 °C for 3 - 5 hours;

[0025] S204 After the dropwise addition is completed, keep the temperature at 190 - 200 °C for 1 - 1.5 hours, supplement the peroxide initiator and continue to keep the temperature for 1.5 - 3 hours;

[0026] S205 Cool down to 70 - 90 °C, and after passing the inspection, package it to obtain the hydroxyl acrylic resin.

[0027] As a preferred technical solution, the weight ratio of the polyester polyol to the propylene glycol methyl ether acetate in step S201 is (10 - 20):(7 - 8.5).

[0028] As a preferred technical solution, in step S202, the mixed monomer accounts for 65% - 80% of the total system weight, the peroxide initiator accounts for 1.5% - 2% of the total system weight, and the weight ratio of the styrene monomer, (meth)acrylate monomer and hydroxyl-containing monomer in the mixed monomer is 15 - 20:30 - 50:10 - 30. The (meth)acrylate monomer includes isobornyl methacrylate and isooctyl acrylate; the hydroxyl-containing monomer includes 2-hydroxyethyl methacrylate; the peroxide initiator includes di-tert-butyl peroxide.

[0029] As a preferred technical solution, the pressure under the pressurized condition in step S203 is 0.1 - 0.5 MPa, and the peroxide initiator supplemented in step S204 accounts for 1% - 2% of the total system weight.

[0030] On the other hand, the present invention provides a hydroxyl acrylic resin prepared by the preparation method of the hydroxyl acrylic resin according to any one of the above.

[0031] On yet another aspect, the application of the hydroxyl acrylic resin as described above in a high-solids coating.

[0032] The hydroxyl acrylic resin, its preparation method and application provided by the present invention have the following

[0033] Beneficial effects:

[0034] 1) The present invention provides a hydroxyl acrylic resin that takes into account high solid content, low viscosity, and low VOC, as well as its preparation method and application. By optimizing the process synergy of polyester synthesis and acrylic polymerization, the limitation that performance and environmental protection are difficult to coexist in the prior art is broken through, ensuring the construction performance and environmental protection indicators.

[0035] 2) For a hydroxyl acrylic resin, its preparation method and application provided by the present application, a ternary alcohol and a binary alcohol are compounded, and by adjusting the weight ratio of the two, the degree of branching of the polyester polyol is controlled to avoid excessive crosslinking resulting in too high a molecular weight, while ensuring sufficient hydroxyl density to increase the solid content. In step S105 of the present application, by adding a high-boiling-point environmentally friendly diluent (such as butyl acetate), the solid content is accurately adjusted to 80-90%, reducing the amount of low-boiling-point solvents and directly reducing VOC emissions.

[0036] A long-chain fatty acid (such as isononanoic acid) is added to the raw materials of the present application, and its long carbon chain structure can reduce the intermolecular force and reduce the resin viscosity. In step S103 of the present application, xylene is used as an azeotropic solvent, and the reaction by-product water is efficiently removed by azeotropic distillation to avoid the increase in viscosity caused by intermolecular hydrogen bonds due to residual hydroxyl groups.

[0037] In step S104 of the present application, by detecting and controlling the acid value to be 8-15 mgKOH / g, the influence of residual carboxyl groups on the volatility of the solvent is reduced; at the same time, a low-toxicity solvent (such as butyl acetate) is selected to replace traditional xylene to reduce VOC emissions. In steps S102 and S103 of the present application, a two-stage high-temperature reaction (220-240°C → 220-235°C) is adopted to promote the complete esterification reaction, reduce the residual amount of unreacted monomers, avoid the increase in the amount of subsequent diluents, and reduce the production cost.

[0038] 3) A hydroxyl acrylic resin provided by the present invention, its preparation method and application. Propylene glycol methyl ether acetate is used as the initial solvent to reduce the initial viscosity of the system, ensure the full dissolution and uniform dispersion of the polyester polyol, and avoid local agglomeration; Diluting propylene glycol methyl ether acetate is used to adjust the viscosity gradient during the subsequent monomer dropping, maintain the fluidity of the reaction system, and prevent gelation or uneven molecular weight distribution caused by too high monomer concentration; In steps S203 - S204, the pressure is increased and the temperature is raised to 190 - 200 °C. High temperature accelerates the generation of free radicals and monomer conversion rate, shortening the reaction time to 3 - 5 hours (the traditional process requires 8 - 12 hours); The pressurized condition inhibits the volatilization of propylene glycol methyl ether acetate (boiling point 146 °C), maintains the stability of the solvent content, and avoids drastic fluctuations in the system viscosity. The peroxide initiator is added in stages. The first addition of the peroxide initiator: starts the main chain polymerization reaction to achieve a monomer conversion rate of >90%; The second addition of the peroxide initiator: consumes the residual monomer (target <1%) to reduce the impact of unreacted monomers on the resin stability, and at the same time avoids side reactions (such as chain transfer or branching). Detailed Embodiment

[0039] The preferred embodiments of the present invention will be described in detail below.

[0040] The present invention provides a preparation method of a hydroxyl acrylic resin, comprising the following steps:

[0041] S1 Synthesize a polyester polyol, comprising the following steps:

[0042] S101 Put a polyester raw material containing at least a triol, a diol, a cyclic anhydride and a long-chain fatty acid into a reaction kettle, and control the top temperature of the reaction kettle to be 95 - 110 °C;

[0043] S102 Heat the reaction kettle to the first temperature range of 220 - 240 °C, and keep it warm at 215 - 235 °C for 50 - 70 minutes;

[0044] S103 Cool down to 170 - 190 °C, add an azeotropic solvent for dehydration, and then heat up to the second temperature range of 220 - 235 °C for continuous reaction;

[0045] S104 After reacting for 2.5 - 3.5 hours, take a sample for detection and control the acid value to be 8 - 15 mgKOH / g;

[0046] S105 Cool down to 130 - 150 °C, add a diluent to adjust the solid content to 75 - 85%, and finally cool down to 80 - 100 °C and package to obtain the polyester polyol;

[0047] S2 Use the polyester polyol to synthesize a hydroxyl acrylic resin to obtain the hydroxyl acrylic resin.

[0048] The present invention provides a hydroxyl acrylic resin that takes into account high solid content, low viscosity, and low VOC, as well as its preparation method and application. By optimizing the process synergy of polyester synthesis and acrylic polymerization, the limitation that performance and environmental protection are difficult to coexist in the prior art is broken through, ensuring the construction performance and environmental protection indicators.

[0049] Preferably, the trihydric alcohol includes trimethylolpropane, the dihydric alcohol includes neopentyl glycol, the cyclic anhydride includes hexahydrophthalic anhydride, and the long-chain fatty acid includes isononanoic acid; the trihydric alcohol and the dihydric alcohol account for 30% - 70% of the total mass of the raw materials. Among them, the weight ratio of the trihydric alcohol to the dihydric alcohol is 1:2.2 - 3.8, the cyclic anhydride and the long-chain fatty acid account for 30% - 70% of the total mass of the raw materials. Among them, the weight ratio of the cyclic anhydride to the long-chain fatty acid is 1:1.1 - 1.6.

[0050] Preferably, the azeotropic solvent in step S103 is xylene, and the addition amount is 3% - 10% of the total mass of the reaction system. And azeotropic dehydration is carried out through a reflux device, and the heating rate after dehydration is 3 - 8 °C / min.

[0051] Preferably, the diluent in step S105 includes butyl acetate.

[0052] Preferably, step S2 uses a polyester polyol to synthesize a hydroxyl acrylic resin to obtain a hydroxyl acrylic resin, including the following steps:

[0053] S201 Put the polyester polyol and propylene glycol methyl ether acetate into a reaction vessel;

[0054] S202 Dropwise add a mixed monomer of styrene monomer, (meth)acrylate monomer, and hydroxyl-containing monomer, and a peroxide initiator into the reaction vessel;

[0055] S203 Under a pressurized condition, heat up to 190 - 200 °C, and dropwise add the mixed monomer at a temperature of 190 - 200 °C for 3 - 5 hours;

[0056] S204 After the dropwise addition is completed, keep the temperature at 190 - 200 °C for 1 - 1.5 hours, supplement the peroxide initiator and continue to keep the temperature for 1.5 - 3 hours;

[0057] S205 Cool down to 70 - 90 °C, and after passing the inspection, package to obtain the hydroxyl acrylic resin.

[0058] Preferably, the weight ratio of the polyester polyol to the propylene glycol methyl ether acetate in step S201 is (10 - 20):(7 - 8.5).

[0059] Preferably, in step S202, the mixed monomers account for 65% to 80% of the total system weight, the peroxide initiator accounts for 1.5 to 2% of the total system weight, and the weight ratio of the styrene monomer, (meth)acrylate monomer, and hydroxyl-containing monomer in the mixed monomers is 15 to 20:30 to 50:10 to 30. The (meth)acrylate monomer includes isobornyl methacrylate and isooctyl acrylate; the hydroxyl-containing monomer includes 2-hydroxyethyl methacrylate; the peroxide initiator includes di-tert-butyl peroxide.

[0060] Preferably, the pressure in step S203 under pressure is 0.1 to 0.5 MPa, and the peroxide initiator added in step S204 accounts for 1 to 2% of the total system weight.

[0061] On the other hand, the present invention provides a hydroxyl acrylic resin prepared by the preparation method of the hydroxyl acrylic resin according to any one of the above, and the main technical indicators of the hydroxyl acrylic resin are as follows:

[0062] 1. Solid content: 83 - 87% (baked at 130 °C for 1.5 hours);

[0063] 2. Acid value: ≤5 mgKOH / g;

[0064] 3. Color: ≤1# (iron cobalt colorimetric);

[0065] 4. Fineness: ≤15 microns;

[0066] 5. Hydroxyl value (solid): 165 mgKOH / g;

[0067] 6. Appearance: clear and transparent liquid.

[0068] On the other hand, the application of the hydroxyl acrylic resin as described above in a high-solid coating.

[0069] Example 1

[0070] The present invention provides a preparation method of a hydroxyl acrylic resin, comprising the following steps:

[0071] S1 Synthesize a polyester polyol, comprising the following steps:

[0072] S101 Put the polyester raw materials of trihydric alcohol, dihydric alcohol, cyclic anhydride and long-chain fatty acid into the reaction kettle, and control the top temperature of the reaction kettle at 101 °C. Among them, the trihydric alcohol is trimethylolpropane, the dihydric alcohol is neopentyl glycol, the trihydric alcohol and the dihydric alcohol account for 30% of the total mass of the raw materials, the weight ratio of the trihydric alcohol to the dihydric alcohol is 1:2.2, the cyclic anhydride is hexahydrophthalic anhydride, the long-chain fatty acid is isononanoic acid, the cyclic anhydride and the long-chain fatty acid account for 60% of the total mass of the raw materials, and the weight ratio of the cyclic anhydride to the long-chain fatty acid is 1:1.1;

[0073] S102 Heat up the reaction kettle to the first temperature range of 230 °C, and keep it warm at 225 - 230 °C for 60 minutes;

[0074] S103 Cool down to 180 °C, add an azeotropic solvent for dehydration, and then heat up to the second temperature range of 225 - 230 °C for continuous reaction. The azeotropic solvent is xylene, and the addition amount is 8% of the total mass of the reaction system. And carry out azeotropic dehydration through a reflux device. After dehydration, the heating rate is 3 °C / min;

[0075] S104 After reacting for 3 hours, take a sample for detection and control the acid value to be 10 - 12.5 mgKOH / g;

[0076] S105 Cool down to 145 °C, add a diluent to adjust the solid content to 80%, and finally cool down to 90 °C for packaging to obtain polyester polyol. Among them, the diluent is butyl acetate;

[0077] S2 Use polyester polyol to synthesize hydroxy acrylic resin to obtain hydroxy acrylic resin, including the following steps:

[0078] S201 Put the polyester polyol and propylene glycol methyl ether acetate into the reaction container. Among them, the weight ratio of the polyester polyol to the propylene glycol methyl ether acetate is 10:9, and the weight ratio of the bottom-filling propylene glycol methyl ether acetate to the diluting propylene glycol methyl ether acetate is 8:1;

[0079] S202 Dropwise add a mixed monomer of styrene monomer, (meth)acrylate monomer and hydroxy-containing monomer and a peroxide initiator into the reaction container. Among them, the mixed monomer accounts for 77.5% of the total system weight, the peroxide initiator accounts for 2% of the total system weight. The weight ratio of the styrene monomer, (meth)acrylate monomer and hydroxy-containing monomer in the mixed monomer is 15:30:10. The (meth)acrylate monomer is isobornyl methacrylate and isooctyl acrylate; among them, the weight ratio of isobornyl methacrylate to isooctyl acrylate is 1:1, the hydroxy-containing monomer is 2-hydroxyethyl methacrylate; the peroxide initiator is di-tert-butyl peroxide;

[0080] S203 is heated to 195 °C under pressure, and the mixed monomers are added dropwise at 195 °C over 4 hours, where the pressure under pressure is 0.1 MPa

[0081] After the addition is completed, it is kept at 195 °C for 1 hour, a peroxide initiator is added and the insulation is continued for 2 hours, where the added peroxide initiator accounts for 1.5% of the total system weight;

[0082] S205 is cooled to 80 °C, and after passing the inspection, it is packaged to obtain a hydroxyl acrylic resin.

[0083] The hydroxyl acrylic resin provided in this example is prepared according to the preparation method of the hydroxyl acrylic resin described above.

[0084] Example 2

[0085] The present invention provides a method for preparing a hydroxyl acrylic resin, which includes the following steps:

[0086] S1 Synthesize a polyester polyol, which includes the following steps:

[0087] S101 Put the polyester raw materials of triol, diol, cyclic anhydride and long-chain fatty acid into the reaction kettle, and control the top temperature of the reaction kettle to be 95 °C. Among them, the triol is trimethylolpropane, the diol is neopentyl glycol, the triol and the diol account for 60% of the total mass of the raw materials, the weight ratio of the triol to the diol is 1:3, the cyclic anhydride is hexahydrophthalic anhydride, the long-chain fatty acid is isononanoic acid, the cyclic anhydride and the long-chain fatty acid account for 30% of the total mass of the raw materials, and the weight ratio of the cyclic anhydride to the long-chain fatty acid is 1:1.4;

[0088] S102 Heat the reaction kettle to the first temperature range of 220 °C, and keep it at 215 - 235 °C for 70 minutes;

[0089] S103 Cool down to 170 °C, add an azeotropic solvent for dehydration, and then heat up to the second temperature range of 220 - 235 °C for continuous reaction. The azeotropic solvent is xylene, and the addition amount is 3% of the total mass of the reaction system. And carry out azeotropic dehydration through a reflux device, and the heating rate after dehydration is 5 °C / min;

[0090] After reacting for 3.5 hours, take a sample for inspection and control the acid value to be 10 - 12.5 mgKOH / g;

[0091] S105 Cool to 130 °C, add a diluent to adjust the solid content to 78%, and finally cool to 80 °C and package to obtain a polyester polyol. The diluent is butyl acetate;

[0092] S2 synthesizes hydroxyl acrylic resin using polyester polyol to obtain hydroxyl acrylic resin, including the following steps:

[0093] S201 Put polyester polyol and propylene glycol methyl ether acetate into a reaction vessel. Among them, the weight ratio of the polyester polyol to the propylene glycol methyl ether acetate is 15:7.5, and the weight ratio of the bottom-filling propylene glycol methyl ether acetate and the diluting propylene glycol methyl ether acetate is 7.5:1;

[0094] S202 Dropwise add a mixed monomer of styrene monomer, (meth)acrylate monomer and hydroxyl-containing monomer and a peroxide initiator into the reaction vessel. Among them, the mixed monomer accounts for 74% of the total system weight, the peroxide initiator accounts for 1.5% of the total system weight, and the weight ratio of the styrene monomer, (meth)acrylate monomer and hydroxyl-containing monomer in the mixed monomer is 18:40:20. The (meth)acrylate monomer is isobornyl methacrylate and isooctyl acrylate; among them, the weight ratio of the isobornyl methacrylate to the isooctyl acrylate is 1:1, the hydroxyl-containing monomer is 2-hydroxyethyl methacrylate; the peroxide initiator is di-tert-butyl peroxide;

[0095] S203 Heat up to 190 °C under pressure and dropwise add the mixed monomer at 190 °C for 5 hours. The pressure under pressure is 0.3 MPa;

[0096] S204 After the dropwise addition is completed, keep the temperature at 190 °C for 1.5 hours, add a supplementary peroxide initiator and continue to keep the temperature for 1.5 hours. The supplementary peroxide initiator accounts for 2% of the total system weight;

[0097] S205 Cool down to 70 °C, and after passing the inspection, package to obtain hydroxyl acrylic resin.

[0098] The hydroxyl acrylic resin provided in this example is prepared according to the preparation method of the hydroxyl acrylic resin described above.

[0099] Example 3

[0100] The present invention provides a preparation method of hydroxyl acrylic resin, including the following steps:

[0101] S1 synthesizes polyester polyol, including the following steps:

[0102] S101 Charge the polyester raw materials of triol, diol, cyclic anhydride and long-chain fatty acid into a reaction kettle, and control the temperature at the top of the reaction kettle column to be 110 °C. The triol is trimethylolpropane, the diol is neopentyl glycol, the cyclic anhydride is hexahydrophthalic anhydride, and the long-chain fatty acid is isononanoic acid. The triol and the diol account for 45% of the total mass of the raw materials. Among them, the weight ratio of the triol to the diol is 1:3.8. The cyclic anhydride and the long-chain fatty acid account for 45% of the total mass of the raw materials. Among them, the weight ratio of the cyclic anhydride to the long-chain fatty acid is 1:1.6;

[0103] S102 Heat the reaction kettle to the first temperature range of 240 °C and keep it warm at 215 - 235 °C for 65 minutes;

[0104] S103 Cool down to 190 °C, add an azeotropic solvent for dehydration, and then heat up to the second temperature range of 220 - 235 °C for continuous reaction. The azeotropic solvent is xylene, and the addition amount is 5% of the total mass of the reaction system. And carry out azeotropic dehydration through a reflux device. After dehydration, the heating rate is 8 °C / min;

[0105] S104 After reacting for 2.5 hours, take a sample for detection and control the acid value to be 8 - 15 mgKOH / g;

[0106] S105 Cool down to 150 °C, add a diluent to adjust the solid content to 85%, and finally cool down to 100 °C for packaging to obtain polyester polyol. The diluent is butyl acetate;

[0107] S2 Synthesize hydroxy acrylic resin using polyester polyol to obtain hydroxy acrylic resin, including the following steps:

[0108] S201 Put the polyester polyol and propylene glycol methyl ether acetate into a reaction container. The weight ratio of the polyester polyol to the propylene glycol methyl ether acetate is 20:7. Among them, the weight ratio of the bottom-filling propylene glycol methyl ether acetate to the diluting propylene glycol methyl ether acetate is 7:1;

[0109] S202 Dropwise add a mixed monomer of styrene monomer, (meth)acrylate monomer and hydroxy-containing monomer and a peroxide initiator into the reaction container. The mixed monomer accounts for 70% of the total system weight, and the peroxide initiator accounts for 1.5% of the total system weight. The weight ratio of the styrene monomer, (meth)acrylate monomer and hydroxy-containing monomer in the mixed monomer is 20:50:30. The (meth)acrylate monomer is isobornyl methacrylate and isooctyl acrylate. Among them, the weight ratio of isobornyl methacrylate to isooctyl acrylate is 1:1. The hydroxy-containing monomer is 2-hydroxyethyl methacrylate. The peroxide initiator is di-tert-butyl peroxide;

[0110] S203 is heated to 200 °C under pressure, and the mixed monomers are added dropwise at a temperature of 200 °C over 3 hours. The pressure under pressure is 0.5 MPa;

[0111] After the addition is completed, it is kept warm at 200 °C for 1 hour, a peroxide initiator is added, and the insulation is continued for 3 hours;

[0112] It is cooled to 90 °C, and after passing the inspection, it is packaged to obtain a hydroxy acrylic resin.

[0113] The hydroxy acrylic resin provided in this example is prepared according to the preparation method of the hydroxy acrylic resin described above.

[0114] Comparative Example 1

[0115] Comparative Example 1 provides a preparation method of a hydroxy acrylic resin, including the following steps:

[0116] S201 Put propylene glycol methyl ether acetate into the reaction vessel, where the propylene glycol methyl ether acetate accounts for 9% of the total system weight;

[0117] S202 Add dropwise a mixed monomer of styrene monomer, (meth)acrylate monomer and hydroxy-containing monomer and a peroxide initiator into the reaction vessel. Among them, the mixed monomer accounts for 77.5% of the total system weight, the peroxide initiator accounts for 2% of the total system weight, and the weight ratio of the styrene monomer, (meth)acrylate monomer and hydroxy-containing monomer in the mixed monomer is 15:30:10. The (meth)acrylate monomer is isobornyl methacrylate and isooctyl acrylate; among them, the weight ratio of isobornyl methacrylate and isooctyl acrylate is 1:1, the hydroxy-containing monomer is hydroxyethyl methacrylate; the peroxide initiator is di-tert-butyl peroxide;

[0118] S203 is heated to 195 °C under pressure, and the mixed monomers are added dropwise at a temperature of 195 °C over 4 hours, where the pressure under pressure is 0.1 MPa;

[0119] After the addition is completed, it is kept warm at 195 °C for 1 hour, a peroxide initiator is added, and the insulation is continued for 2 hours, where the added peroxide initiator accounts for 1.5% of the total system weight;

[0120] It is cooled to 80 °C, and after passing the inspection, it is packaged to obtain a hydroxy acrylic resin.

[0121] The hydroxy acrylic resin provided in Comparative Example 1 is prepared according to the preparation method of the hydroxy acrylic resin described above.

[0122] Comparative Example 2

[0123] Comparative Example 2 provides a method for preparing a hydroxyl acrylic resin, comprising the following steps:

[0124] S201 Put propylene glycol methyl ether acetate into the reaction vessel, wherein the propylene glycol methyl ether acetate accounts for 7.5% of the total system weight, and the weight ratio of the bottom-filling propylene glycol methyl ether acetate to the diluting propylene glycol methyl ether acetate is 7.5:1;

[0125] S202 Dropwise add a mixed monomer of styrene monomer, (meth)acrylate monomer and hydroxyl-containing monomer and a peroxide initiator into the reaction vessel, wherein the mixed monomer accounts for 74% of the total system weight, the peroxide initiator accounts for 1.5% of the total system weight, and the weight ratio of the styrene monomer, (meth)acrylate monomer and hydroxyl-containing monomer in the mixed monomer is 18:40:20. The (meth)acrylate monomer is isobornyl methacrylate and isooctyl acrylate; wherein, the weight ratio of isobornyl methacrylate to isooctyl acrylate is 1:1, and the hydroxyl-containing monomer is hydroxyethyl methacrylate; the peroxide initiator is di-tert-butyl peroxide;

[0126] S203 Heat up to 190 °C under pressure, and dropwise add the mixed monomer at 190 °C for 5 hours. The pressure under the pressurized condition is 0.3 MPa;

[0127] S204 After the dropping is completed, keep the temperature at 190 °C for 1.5 hours, supplement the peroxide initiator and continue to keep the temperature for 1.5 hours. The supplemented peroxide initiator accounts for 2% of the total system weight;

[0128] S205 Cool down to 70 °C, and after passing the inspection, package to obtain the hydroxyl acrylic resin.

[0129] The hydroxyl acrylic resin provided by the comparative example is prepared according to the above-mentioned method for preparing the hydroxyl acrylic resin.

[0130] Experimental means

[0131] The properties of the hydroxyl acrylic resins prepared in Examples 1-3 and Comparative Examples 1-2 were tested by the following experimental means:

[0132] I. Format tube viscosity (s) test

[0133] 1. Specimen treatment: Pour the liquid specimen to be tested into the format tube, adjust the liquid level to about the 100 mm graduation line, seal it and place it in a constant temperature water bath at 25 °C for 10 minutes for constant temperature.

[0134] 2. Constant temperature adjustment: Adjust the liquid level to the 100 mm graduation line again, and continue to keep the temperature for 10 minutes to ensure uniform temperature.

[0135] 3. Viscosity measurement: Quickly invert the viscosity tube and fix it vertically in a 25°C water bath. Record the time (in seconds) required for the bubble to rise from the bottom to the top of the tube.

[0136] 4. Result processing: Each sample needs to be measured three times. The relative error of a single result is required to be ≤3%. Finally, take the average of the three measured values as the viscosity result.

[0137] II. Determination of solid content (%)

[0138] 1. Sample weighing: Weigh the mass of a clean and dry tin foil and a paper clip (denoted as m0). After taring, add 1.0 ± 0.1 g of the sample to be measured (denoted as m1) and spread it flat on the tin foil.

[0139] 2. Solvent treatment: Add about 10 g of neutral solvent, stir the sample with a paper clip until it is uniform, and let it stand for 5 minutes. The neutral solvent is, for example, a 7:3 volume ratio mixture of toluene and anhydrous methanol.

[0140] 3. Drying and constant weight: Place the sample in an oven at 108 ± 2°C for 1 hour. After taking it out, transfer it to a desiccator and cool it to room temperature, then weigh the mass of the residue (denoted as m2).

[0141] 4. The solid content of the sample is obtained by the following calculation formula: solid content Obtained;

[0142] 5. Parallel test: The same sample needs to be tested in parallel at least twice. Finally, take the average of the two measured values as the solid content test result.

[0143] III. VOC (g / L) detection

[0144] 1. Sample preparation

[0145] Weigh 1.0 ± 0.01 g of the sample into a headspace vial, add 5 mL of methanol to dissolve it, seal it, and ultrasonically treat it for 10 minutes.

[0146] Prepare 3 samples in parallel and set a blank control (containing only methanol).

[0147] 2. Headspace injection parameters

[0148] Equilibrium temperature: 80°C; Equilibrium time: 30 minutes; Injection volume: 1.0 mL.

[0149] Carrier gas flow rate: 1.0 mL / min (nitrogen), split ratio 10:1.

[0150] 3. GC-MS conditions

[0151] Chromatographic column: DB-5MS (30 m × 0.25 mm × 0.25 μm);

[0152] Temperature rising program: Initially maintain at 50°C for 2 minutes, then increase to 250°C at a rate of 10°C / min and maintain for 5 minutes.

[0153] Mass spectrometry parameters: EI ion source (70 eV), scanning range m / z 35 - 350.

[0154] 4. Data collection and processing

[0155] Quantify using the internal standard method (such as deuterated benzene), and calculate the VOC concentration through the standard curve.

[0156] Conduct three parallel tests, and finally take the average of the three measured values as the VOC (g / L) test result.

[0157] The experimental data of the hydroxyl acrylic resins prepared in Examples 1 - 3 and Comparative Examples 1 - 2 after being tested by the above experimental methods are shown in Table 1 below:

[0158] Table 1 Experimental data of the hydroxyl acrylic resins prepared in Examples 1 - 3 and Comparative Examples 1 - 2 after testing

[0159]

[0160] From Table 1, we can observe that the form tube viscosity and VOC of the hydroxyl acrylic resin prepared in Example 1 are both decreased compared with those of the hydroxyl acrylic resin prepared in Comparative Example 1, and high solid content is maintained; the form tube viscosity and VOC of the hydroxyl acrylic resin prepared in Example 2 are both decreased compared with those of the hydroxyl acrylic resin prepared in Comparative Example 2, and high solid content is maintained. This is due to the synergistic effect of the branched structure of the polyester polyol prepared in this application and the lubrication of the long-chain fatty acid, which reduces the form tube viscosity of the hydroxyl acrylic resin; the polyester polyol itself acts as an active diluent, replacing part of the propylene glycol methyl ether acetate, and the synergistic effect of adopting the pressurized polymerization process reduces the volatilization of solvents and monomers, resulting in a decrease in VOC; by controlling the acid value (8 - 15 mgKOH / g) and the stepwise polycondensation process (high-temperature polycondensation at 220 - 240°C + azeotropic dehydration), the number-average molecular weight of the polyester polyol is reduced, avoiding a sharp increase in viscosity caused by too high molecular weight. At the same time, the ester groups of the polyester polyol form a hydrogen bond network with the hydroxyl groups of the acrylic resin, enhancing the compatibility with the solvent, and enabling the solid content to still maintain fluidity when increased to 85%, realizing the performance of high solid content.

[0161] It will be understood that the present invention is described by way of some embodiments, and those skilled in the art will be aware that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. Additionally, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all changes or equivalent substitutions that fall within the scope of the claims of this application are covered. Additionally, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments that fall within the scope of the claims of this application are within the scope protected by the present invention.

Claims

1. A preparation method of a hydroxyl acrylic resin, characterized in that, It includes the following steps: S1 Synthesize polyester polyol, which includes the following steps: S101 Put polyester raw materials containing at least triol, diol, cyclic anhydride and long-chain fatty acid into a reaction kettle, and control the top temperature of the reaction kettle to be 95 - 110 °C; S102 Heat the reaction kettle to the first temperature range of 220 - 240 °C, and keep it warm at 215 - 235 °C for 50 - 70 minutes; S103 Cool down to 170 - 190 °C, add an azeotropic solvent for dehydration, and then heat up to the second temperature range of 220 - 235 °C for continuous reaction; S104 After reacting for 2.5 - 3.5 hours, take a sample for detection and control the acid value to be 8 - 15 mgKOH / g; S105 Cool down to 130 - 150 °C, add a diluent to adjust the solid content to 75 - 85%, and finally cool down to 80 - 100 °C for packaging to obtain polyester polyol; S2 Use the polyester polyol to synthesize hydroxy acrylic resin to obtain hydroxy acrylic resin.

2. The preparation method of the hydroxyl acrylic resin according to claim 1, characterized in that The triol includes: trimethylolpropane, the diol includes: neopentyl glycol, the cyclic anhydride includes: hexahydrophthalic anhydride, the long-chain fatty acid includes: isononanoic acid; the triol and the diol account for 30% - 70% of the total mass of the raw materials, wherein, the weight ratio of the triol to the diol is 1:2.2 - 3.8, the cyclic anhydride and the long-chain fatty acid account for 30% - 70% of the total mass of the raw materials, wherein, the weight ratio of the cyclic anhydride to the long-chain fatty acid is 1:1.1 - 1.

6.

3. The preparation method of the hydroxy acrylic resin according to claim 1, characterized in that, In step S103, the azeotropic solvent is xylene, and the addition amount is 3% - 10% of the total mass of the reaction system, and azeotropic dehydration is carried out through a reflux device, and the heating rate after dehydration is 3 - 8 °C / min.

4. The preparation method of the hydroxy acrylic resin according to claim 1, characterized in that, In step S105, the diluent includes: butyl acetate.

5. The preparation method of the hydroxyl acrylic resin according to claim 1, characterized in that, Step S2 uses the polyester polyol to synthesize hydroxy acrylic resin to obtain hydroxy acrylic resin, which includes the following steps: S201 Put the polyester polyol and propylene glycol monomethyl ether acetate into a reaction container; S202 Dropwise add a mixed monomer of styrene monomer, (meth)acrylate monomer and hydroxy-containing monomer and a peroxide initiator into the reaction container; S203 Under pressurized conditions, heat up to 190 - 200 °C, and dropwise add the mixed monomer at a temperature of 190 - 200 °C for 3 - 5 hours; S204 After the dropwise addition is completed, keep it warm at a temperature of 190 - 200 °C for 1 - 1.5 hours, replenish the peroxide initiator and continue to keep it warm for 1.5 - 3 hours; S205 Cool down to 70 - 90 °C, and after passing the inspection, package it to obtain hydroxy acrylic resin.

6. The preparation method of the hydroxyl acrylic resin according to claim 5, characterized in that, In step S201, the weight ratio of the polyester polyol to the propylene glycol monomethyl ether acetate is (10 - 20):(7 - 8.5), the propylene glycol monomethyl ether acetate includes: bottom-filling propylene glycol monomethyl ether acetate and diluting propylene glycol monomethyl ether acetate, and the weight ratio of the bottom-filling propylene glycol monomethyl ether acetate to the diluting propylene glycol monomethyl ether acetate is (8 - 7):

1.

7. The preparation method of the hydroxyl acrylic resin according to claim 5, characterized in that, In step S202, the mixed monomers account for 65% to 80% of the total system weight, the peroxide initiator accounts for 1.5 to 2% of the total system weight, and the weight ratio of the styrene monomer, (meth)acrylate monomer, and hydroxyl-containing monomer in the mixed monomers is 15 to 20:30 to 50:10 to 30. The (meth)acrylate monomer includes isobornyl methacrylate and isooctyl acrylate; the hydroxyl-containing monomer includes 2-hydroxyethyl methacrylate; the peroxide initiator includes di-tert-butyl peroxide.

8. The preparation method of the hydroxyl acrylic resin according to claim 5, characterized in that, The pressure in step S203 under pressurized conditions is 0.1 to 0.5 MPa, and the peroxide initiator added in step S204 accounts for 1 to 2% of the total system weight.

9. A hydroxyl acrylic resin, characterized in that, It is prepared by the method for preparing a hydroxyl acrylic resin according to any one of claims 1-8.

10. The application of the hydroxyl acrylic resin according to claim 9 in a high-solids coating.

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