High-hydroxyl acrylic emulsion and synthesis method thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to a high-hydroxyl acrylic emulsion and a synthesis method thereof. The preparation raw materials comprise 390 to 460 parts of a vinyl monomer, 150 to 290 parts of a hydroxy acrylic monomer, 12 to 20 parts of an anionic emulsifier, 1 to 2 parts of a nonionic emulsifier, 0.5 to 1 part of a chain transfer agent, 2 to 4 parts of an initiator, 1 to 1.4 parts of a buffer agent, 0.5 to 1 part of an oxidant, 0.3 to 0.8 part of a reducing agent, 4 to 6 parts of a neutralizer and 728 to 900 parts of deionized water. According to the invention, the modified hydroxyl monomer is synthesized by reacting the monofunctional epoxy diluent with the acrylic acid, and the specific chain transfer agent mercaptoethanol is introduced, so that the synthesized high-hydroxyl acrylic emulsion has the advantages of high gloss, good tolerance and long activation period, and can meet the requirement of long-term use.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a high-hydroxyl acrylic emulsion and a synthesis method thereof. Background Art

[0002] In recent years, with the enhancement of environmental awareness, waterborne coatings have become the main substitute for traditional solvent-based coatings due to their advantages such as non-toxicity, no peculiar smell, non-flammability, and easy cleaning. Among them, hydroxyl acrylic emulsion, as the main film-forming substance in the waterborne two-component polyurethane coating system, has excellent properties such as appearance, adhesion, abrasion resistance, and chemical resistance, and is widely used in the fields of automobiles, woodware, leather, industry, etc.

[0003] However, there are some problems in preparing high-hydroxyl-content hydroxyl acrylic emulsion by traditional emulsion polymerization method. For example, Chinese Patent Application CN106699957A provides a preparation method of hydroxyl acrylic emulsion. Using methyl methacrylate, butyl acrylate, methacrylic acid, styrene, and 2-hydroxyethyl methacrylate as copolymer monomers to prepare hydroxyl acrylic emulsion for glass paint. When preparing high-hydroxyl-content hydroxyl acrylic emulsion, it is necessary to increase the usage amount of hydrophilic hydroxyl monomers, which leads to a large amount of gel in emulsion polymerization, and at the same time results in insufficient effective hydroxyl groups on emulsion particles, and then leads to the inability of hydroxyl groups to be evenly distributed on the molecular main chain, thus unable to stably synthesize high-hydroxyl-content hydroxyl acrylic emulsion, and resulting in poor water resistance and short activation period after formulating the paint. Summary of the Invention

[0004] In view of the problems in the prior art, the first aspect of the present invention provides a high-hydroxyl acrylic emulsion. Calculated by weight parts, the raw materials for preparation include: 390 - 460 parts of vinyl monomers, 150 - 290 parts of hydroxyl acrylic monomers, 12 - 20 parts of anionic emulsifiers, 1 - 2 parts of nonionic emulsifiers, 0.5 - 1 part of chain transfer agents, 2 - 4 parts of initiators, 1 - 1.4 parts of buffers, 0.5 - 1 part of oxidants, 0.3 - 0.8 part of reductants, 4 - 6 parts of neutralizing agents, and 728 - 900 parts of deionized water.

[0005] In one embodiment, the hydroxyl acrylic monomers include at least modified hydroxyl acrylic monomers.

[0006] In one embodiment, the hydroxyl acrylic monomers further include at least one of 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate.

[0007] In one embodiment, the hydroxyl acrylic monomers include 2-hydroxyethyl methacrylate and modified hydroxyl acrylic monomers.

[0008] In one embodiment, the raw materials for preparing the modified hydroxy acrylic monomer include a monofunctional epoxy diluent, acrylic acid, hydroquinone, and triphenylphosphine.

[0009] In one embodiment, the molar ratio of the monofunctional epoxy diluent to acrylic acid is (0.8 - 1.2):1; the hydroquinone accounts for 0.9 - 1.5‰ of the total mass of the monofunctional epoxy diluent and acrylic acid; the triphenylphosphine accounts for 4 - 6‰ of the total mass of the monofunctional epoxy diluent and acrylic acid.

[0010] In one embodiment, the monofunctional epoxy diluent is selected from 12-14 at least one of C

[0011] alkyl glycidyl ether, butyl glycidyl ether, benzyl glycidyl ether, and phenyl glycidyl ether.

[0012] In one embodiment, the vinyl monomer is selected from one or more of styrene, n-butyl acrylate, methyl methacrylate, ethyl acrylate, isooctyl methacrylate, isooctyl acrylate, acrylic acid, methacrylic acid, acrylamide, methacrylamide, ethylene urea ethoxy ester methacrylate, or acrylic acid phosphate.

[0013] In one embodiment, the vinyl monomer is selected from acrylamide, acrylic acid, styrene, n-butyl acrylate, and isooctyl acrylate.

[0014] In one embodiment, the chain transfer agent includes mercaptoethanol.

[0015] In one embodiment, the anionic emulsifier is selected from at least one of fatty alcohol polyoxyethylene ether sulfate, alkyl sulfate, and alkyl alcohol ether succinate.

[0016] In one embodiment, the alkyl sulfate is sodium dodecyl sulfate.

[0017] In one embodiment, the nonionic emulsifier includes fatty alcohol polyoxyethylene ethers.

[0018] In one embodiment, the initiator is a persulfate compound, and the persulfate compound includes at least one of ammonium persulfate and potassium persulfate.

[0019] In one embodiment, the buffer is selected from at least one of sodium bicarbonate, ammonium bicarbonate, sodium dihydrogen phosphate, and ammonia water.

[0020] In one embodiment, the oxidizing agent is selected from at least one of hydrogen peroxide and tert-butyl hydroperoxide.

[0021] In one embodiment, the reducing agent is selected from at least one of sodium bisulfite, sodium formaldehyde sulfoxylate, ascorbic acid, and isoascorbic acid.

[0022] In one embodiment, the neutralizing agent is selected from at least one of ammonia water, dimethylethanolamine, 2-amino-2-methyl-1-propanol, sodium hydroxide, and potassium hydroxide.

[0023] The second aspect of the present invention provides a method for synthesizing a high-hydroxyl acrylic emulsion, comprising the following steps:

[0024] S1. Add deionized water and 30-75 wt% anionic emulsifier to a pre-emulsification kettle. After stirring and dissolving until transparent, add vinyl monomers and hydroxyl acrylic monomers, and stir for 30-60 min to obtain a pre-emulsion.

[0025] S2. Dissolve 30-35 wt% initiator in deionized water to form a first initiator solution; dissolve the remaining initiator in deionized water to form a second initiator solution; dissolve the oxidizing agent in 11-14 parts of deionized water to form an oxidizing agent solution; dissolve the reducing agent in 11-14 parts of deionized water to form a reducing agent solution.

[0026] S3. Add a buffer, a non-ionic emulsifier, the remaining deionized water, and the remaining anionic emulsifier to a reaction kettle. After stirring and heating to 80-90 °C, simultaneously add the first initiator solution and 3-10 wt% of the pre-emulsion for an initial reaction.

[0027] S4. After the initial reaction is completed, simultaneously and uniformly add the remaining pre-emulsion and the second initiator solution dropwise. After the addition is completed, keep the temperature at 1-2 h, then cool down to 55-75 °C, and simultaneously add the oxidizing agent solution and the reducing agent solution dropwise. After the addition is completed, keep the temperature at 0.5-1 h to obtain a mixture.

[0028] S5. Cool the mixture to below 40 °C, add a neutralizing agent to adjust the pH to 7-9, filter, and discharge to obtain the high-hydroxyl acrylate emulsion.

[0029] In one embodiment, the stirring speed in step S1 is 400-500 r / min. Examples include 400 r / min, 420 r / min, 450 r / min, and 500 r / min.

[0030] In one embodiment, the temperature of stirring and heating in step S3 is 82-86 °C. Examples include 82 °C, 83 °C, 84 °C, 85 °C, and 86 °C.

[0031] In one embodiment, the initial reaction time in step S3 is 10-15 min, which can be 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min.

[0032] In one embodiment, the remaining pre-emulsion and the second initiator solution are added dropwise for 3-3.5 hours in step S4; and the oxidant and the reductant are added dropwise for 0.5-1 hour.

[0033] Beneficial Effects

[0034] 1. The present invention synthesizes a modified hydroxy acrylic monomer by first reacting a monofunctional epoxy diluent with acrylic acid, wherein the hydroxyl group of the monomer is connected to a long-chain alkyl group or an aromatic hydrophobic group, which significantly reduces the overall hydrophilicity of the hydroxyl monomer; and then pre-emulsifies the monomer with other monomers for emulsion polymerization, which can effectively avoid the problem of increasing the amount of hydrophilic hydroxyl monomer used in the traditional method and causing a large amount of gel to be produced during emulsion polymerization, thereby stably synthesizing a hydroxy acrylic emulsion with a high hydroxyl content.

[0035] 2. The present invention introduces a specific chain transfer agent, mercaptoethanol, which can not only reduce the molecular weight of acrylic resin and improve the gloss of hydroxyl emulsion, but also introduce hydroxyl groups at the end of the molecular weight to improve the uniformity of hydroxyl distribution. The synthesized high-hydroxyl acrylic emulsion has the advantages of high gloss, good resistance and long activation period, which can meet the needs of long-term use.

[0036] 3. The present invention uses specific hydroxy acrylic monomers and vinyl monomers, wherein the hydrophilic hydroxy monomers and the hydrophobic hydroxy monomers assist the polymerization reaction, better adjust the hydrophilic-lipophilic balance of the monomers, and make the reaction process more stable without agglomeration and gelation.

[0037] 4. In the hydroxy acrylic emulsion synthesized by the method of the present invention, the hydroxyl groups can be evenly distributed on the main chain of the molecule, the effective hydroxyl content on the emulsion particles is sufficient, and the paint has good water resistance after being formulated.

[0038] 5. The high-hydroxyl acrylic emulsion provided by the present invention can achieve a long application period. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The experimental methods in the examples without specifying specific conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0040] Example 1

[0041] The first aspect of the present embodiment provides a high hydroxyl acrylic emulsion, and the raw materials for preparation include, by weight: 440.5 parts of vinyl monomer, 290 parts of hydroxyl acrylic monomer, 14.6 parts of anionic emulsifier, 1.7 parts of nonionic emulsifier, 0.5 parts of chain transfer agent, 2.35 parts of initiator, 1.2 parts of buffer, 0.74 parts of oxidant, 0.52 parts of reducing agent, 5 parts of neutralizer and 888.4 parts of deionized water.

[0042] In terms of weight parts, the vinyl monomers include 8.2 parts of acrylamide, 7 parts of acrylic acid, 257.6 parts of styrene, 88.6 parts of n-butyl acrylate and 79.1 parts of isooctyl acrylate.

[0043] In terms of weight parts, the hydroxy acrylic monomer is 90 parts of hydroxyethyl methacrylate and 200 parts of modified hydroxy monomer.

[0044] The raw materials for preparing the modified hydroxyl monomer are 769g of monofunctional epoxy diluent, 205g of acrylic acid, 0.94g of hydroquinone and 4.87g of triphenylphosphine.

[0045] The monofunctional epoxy diluent is C 12-14 Alkyl glycidyl ether.

[0046] The preparation method of the modified hydroxyl monomer is: 12-14 Alkyl glycidyl ether, acrylic acid and hydroquinone are added to a reaction bottle, stirring is started, and triphenylphosphine is added after the temperature is raised to 100° C., and the reaction is carried out for 3 hours. The modified hydroxyl monomer is obtained by cooling.

[0047] The anionic emulsifier is sodium lauryl sulfate.

[0048] The nonionic emulsifier is nonionic emulsifier OP-10.

[0049] The chain transfer agent is mercaptoethanol.

[0050] The initiator is potassium persulfate; the buffer is sodium bicarbonate; the oxidant is tert-butyl hydroperoxide; the reducing agent is sodium bisulfite; and the neutralizing agent is aqueous ammonia.

[0051] A second aspect of the present embodiment provides a method for synthesizing a high-hydroxyl acrylic emulsion, comprising the following steps:

[0052] S1, add 580 parts of deionized water and 7 parts of emulsifier into a pre-emulsification kettle, stir and dissolve until transparent, then add vinyl monomer and hydroxy acrylic monomer, stir at 420r / min for 30min to obtain a pre-emulsion;

[0053] S2. Dissolve 0.8 parts of the initiator in 8 parts of deionized water to form the first initiator solution; dissolve the remaining initiator in 13.4 parts of deionized water to form the second initiator solution; dissolve the oxidant in 13 parts of deionized water to form the oxidant solution; dissolve the reductant in 13 parts of deionized water to form the reductant solution;

[0054] S3. Add 261 parts of deionized water, buffer, non-ionic emulsifier and the remaining anionic emulsifier into the reaction kettle, stir and heat to 85 °C, then add the first initiator solution and 6 wt% of the pre-emulsion simultaneously for the initial reaction for 10 min;

[0055] S4. After the initial reaction is completed, uniformly add the remaining pre-emulsion and the second initiator solution dropwise at the same time. After dropping for 3 h, keep warm for 1.5 h, cool down to 60 °C, and simultaneously add the oxidant and the reductant dropwise. After dropping for 0.5 h, keep warm for 0.5 h to obtain a mixture;

[0056] S5. Cool the mixture to below 40 °C, add a neutralizing agent to adjust the pH to 8, filter and discharge to obtain the high-hydroxyl acrylate emulsion.

[0057] The obtained high-hydroxyl acrylic emulsion has a hydroxyl content of 3%, a viscosity of 1000 mPa·s at 25 °C, and a solid content of 45 wt%.

[0058] Example 2

[0059] The specific implementation method of this example is the same as that of Example 1. The difference is that, by weight, the preparation raw materials include: 390.5 parts of vinyl monomer, 150 parts of hydroxyl acrylic monomer, 14.6 parts of anionic emulsifier, 1.7 parts of non-ionic emulsifier, 0.5 part of chain transfer agent, 2.35 parts of initiator, 1.2 parts of buffer, 0.74 part of oxidant, 0.52 part of reductant, 5 parts of neutralizing agent and 728.4 parts of deionized water.

[0060] By weight, the vinyl monomer is 8.2 parts of acrylamide, 7 parts of acrylic acid, 207.6 parts of styrene, 88.6 parts of n-butyl acrylate and 79.1 parts of isooctyl acrylate.

[0061] By weight, the hydroxyl acrylic monomer is 60 parts of 2-hydroxyethyl methacrylate and 90 parts of modified hydroxyl monomer.

[0062] The preparation raw materials of the modified hydroxyl monomer are 769 g of monofunctional epoxy diluent, 425 g of acrylic acid, 1.2 g of hydroquinone and 6 g of triphenylphosphine.

[0063] The monofunctional epoxy diluent is butyl glycidyl ether.

[0064] In the second aspect of this embodiment, a method for synthesizing a high-hydroxyl acrylic emulsion is provided, which includes the following steps:

[0065] S1. Add 420 parts of deionized water and 7 parts of emulsifier into a pre-emulsification kettle. After stirring and dissolving until transparent, add vinyl monomers and hydroxyl acrylic monomers, and stir at 420 r / min for 30 min to obtain a pre-emulsion.

[0066] S2. Dissolve 0.8 part of initiator in 8 parts of deionized water to form a first initiator solution; dissolve the remaining initiator in 13.4 parts of deionized water to form a second initiator solution; dissolve the oxidant in 13 parts of deionized water to form an oxidant solution; dissolve the reductant in 13 parts of deionized water to form a reductant solution.

[0067] S3. Add 261 parts of deionized water, buffer, non-ionic emulsifier and the remaining anionic emulsifier into a reaction kettle. After stirring and heating to 85 °C, simultaneously add the first initiator solution and 6 wt% of the pre-emulsion for an initial reaction for 10 min.

[0068] S4. After the initial reaction ends, simultaneously and uniformly dropwise add the remaining pre-emulsion and the second initiator solution. After dropping for 3 h, keep warm for 1.5 h, cool down to 60 °C, and simultaneously dropwise add the oxidant and the reductant. After dropping for 0.5 h, keep warm for 0.5 h to obtain a mixture.

[0069] S5. Cool the mixture to below 40 °C, add a neutralizing agent to adjust the pH to 8, filter and discharge to obtain the high-hydroxyl acrylate emulsion.

[0070] The obtained high-hydroxyl acrylic emulsion has a hydroxyl content of 3%, a viscosity of 2300 mPa·s at 25 °C, and a solid content of 45 wt%.

[0071] Example 3

[0072] The specific implementation manner of this embodiment is the same as that of Example 1, the difference is that, by weight, the preparation raw materials include: 390.5 parts of vinyl monomers, 165 parts of hydroxyl acrylic monomers, 14.6 parts of anionic emulsifier, 1.7 parts of non-ionic emulsifier, 0.5 part of chain transfer agent, 2.35 parts of initiator, 1.2 parts of buffer, 0.74 part of oxidant, 0.52 part of reductant, 5 parts of neutralizing agent and 748.4 parts of deionized water.

[0073] By weight, the vinyl monomers are 8.2 parts of acrylamide, 7 parts of acrylic acid, 207.6 parts of styrene, 88.6 parts of n-butyl acrylate and 79.1 parts of isooctyl acrylate.

[0074] By weight, the hydroxyl acrylic monomers are 75 parts of hydroxyethyl methacrylate and 90 parts of modified hydroxyl monomers.

[0075] The raw materials for preparing the modified hydroxyl monomer are 769 g of a monofunctional epoxy diluent, 370 g of acrylic acid, 1.14 g of hydroquinone, and 5.7 g of triphenylphosphine.

[0076] The monofunctional epoxy diluent is phenyl glycidyl ether.

[0077] In the second aspect of this example, a method for synthesizing a high-hydroxyl acrylic emulsion is provided, including the following steps:

[0078] S1. Add 440 parts of deionized water and 7 parts of an emulsifier to a pre-emulsification kettle. After stirring and dissolving until transparent, add vinyl monomers and hydroxyl acrylic monomers, and stir at 420 r / min for 30 min to obtain a pre-emulsion.

[0079] S2. Dissolve 0.8 part of an initiator in 8 parts of deionized water to form a first initiator solution; dissolve the remaining initiator in 13.4 parts of deionized water to form a second initiator solution; dissolve an oxidant in 13 parts of deionized water to form an oxidant solution; dissolve a reducing agent in 13 parts of deionized water to form a reducing agent solution.

[0080] S3. Add 261 parts of deionized water, a buffer, a non-ionic emulsifier, and the remaining anionic emulsifier to a reaction kettle. After stirring and heating to 85 °C, simultaneously add the first initiator solution and 6 wt% of the pre-emulsion for an initial reaction for 10 min.

[0081] S4. After the initial reaction ends, simultaneously and uniformly dropwise add the remaining pre-emulsion and the second initiator solution. After dropping for 3 h, keep warm for 1.5 h, cool down to 60 °C, and simultaneously dropwise add the oxidant and the reducing agent. After dropping for 0.5 h, keep warm for 0.5 h to obtain a mixture.

[0082] S5. Cool the mixture to below 40 °C, add a neutralizing agent to adjust the pH to 8, filter, and discharge to obtain the high-hydroxyl acrylate emulsion.

[0083] The obtained high-hydroxyl acrylic emulsion has a hydroxyl content of 3%, a viscosity of 1500 mPa·s at 25 °C, and a solid content of 45 wt%.

[0084] Example 4

[0085] The specific implementation method of this example is the same as that of Example 1, except that, by weight, the raw materials include: 390.5 parts of vinyl monomers, 180 parts of hydroxyl acrylic monomers, 14.6 parts of anionic emulsifiers, 1.7 parts of non-ionic emulsifiers, 0.5 part of a chain transfer agent, 2.35 parts of an initiator, 1.2 parts of a buffer, 0.74 part of an oxidant, 0.52 part of a reducing agent, 5 parts of a neutralizing agent, and 768.4 parts of deionized water.

[0086] By weight parts, the vinyl monomer is 8.2 parts of acrylamide, 7 parts of acrylic acid, 207.6 parts of styrene, 88.6 parts of n-butyl acrylate and 79.1 parts of isooctyl acrylate.

[0087] By weight parts, the hydroxy acrylic monomer is 90 parts of 2-hydroxyethyl methacrylate and 90 parts of modified hydroxy monomer.

[0088] The raw materials for preparing the modified hydroxy monomer are 769 g of monofunctional epoxy diluent, 335 g of acrylic acid, 1.1 g of hydroquinone and 5.5 g of triphenylphosphine.

[0089] The monofunctional epoxy diluent is benzyl glycidyl ether.

[0090] In the second aspect of this embodiment, a method for synthesizing a high-hydroxy acrylic emulsion is provided, including the following steps:

[0091] S1. Add 460 parts of deionized water and 7 parts of emulsifier into a pre-emulsification kettle. After stirring and dissolving until transparent, add the vinyl monomer and the hydroxy acrylic monomer, and stir at 420 r / min for 30 min to obtain a pre-emulsion.

[0092] S2. Dissolve 0.8 part of initiator in 8 parts of deionized water to form a first initiator solution; dissolve the remaining initiator in 13.4 parts of deionized water to form a second initiator solution; dissolve the oxidant in 13 parts of deionized water to form an oxidant solution; dissolve the reductant in 13 parts of deionized water to form a reductant solution.

[0093] S3. Add a buffer, a non-ionic emulsifier, 261 parts of deionized water and the remaining anionic emulsifier into a reaction kettle. After stirring and heating to 85 °C, simultaneously add the first initiator solution and 6 wt% of the pre-emulsion for an initial reaction for 10 min.

[0094] S4. After the initial reaction ends, simultaneously and uniformly dropwise add the remaining pre-emulsion and the second initiator solution. After dropping for 3 h, keep warm for 1.5 h, cool down to 60 °C, and simultaneously dropwise add the oxidant and the reductant. After dropping for 0.5 h, keep warm for 0.5 h to obtain a mixture.

[0095] S5. Cool the mixture to below 40 °C, add a neutralizer to adjust the pH to 8, filter and discharge to obtain the high-hydroxy acrylate emulsion.

[0096] The obtained high-hydroxy acrylic emulsion has a hydroxy content of 3%, a viscosity of 2500 mPa·s at 25 °C, and a solid content of 45 wt%.

[0097] Comparative Example 1

[0098] The specific implementation of this comparative example is the same as that of Example 1, except that, by weight, the preparation raw materials include: 440.5 parts of vinyl monomer, 135 parts of hydroxy acrylic monomer, 14.6 parts of anionic emulsifier, 1.7 parts of non-ionic emulsifier, 2.35 parts of initiator, 1.2 parts of buffer, 0.74 parts of oxidant, 0.52 parts of reductant, 5 parts of neutralizer and 1100 parts of deionized water.

[0099] The hydroxy acrylic monomer is hydroxyethyl methacrylate.

[0100] The obtained acrylic emulsion has a hydroxy content of 3%, a viscosity of 1500 mPa·s at 25 °C, and a solid content of 35 wt%.

[0101] Comparative Example 2

[0102] The specific implementation of this comparative example is the same as that of Example 1, except that, by weight, the preparation raw materials include: 390.5 parts of vinyl monomer, 120 parts of hydroxy acrylic monomer, 14.6 parts of anionic emulsifier, 1.7 parts of non-ionic emulsifier, 0.5 part of chain transfer agent, 2.35 parts of initiator, 1.2 parts of buffer, 0.74 parts of oxidant, 0.52 parts of reductant, 5 parts of neutralizer and 708.4 parts of deionized water.

[0103] By weight, the vinyl monomer is 8.2 parts of acrylamide, 7 parts of acrylic acid, 207.6 parts of styrene, 88.6 parts of n-butyl acrylate and 79.1 parts of isooctyl acrylate.

[0104] By weight, the hydroxy acrylic monomer is 80 parts of hydroxyethyl methacrylate and 40 parts of modified hydroxy monomer.

[0105] The preparation raw materials of the modified hydroxy monomer are 769 g of epoxy diluent, 630 g of acrylic acid, 1.4 g of hydroquinone and 7 g of triphenylphosphine.

[0106] The epoxy diluent is ethylene glycol diglycidyl ether.

[0107] In the second aspect of this comparative example, a method for synthesizing a high-hydroxy acrylic emulsion is provided, including the following steps:

[0108] S1. Add 400 parts of deionized water and 7 parts of emulsifier to a pre-emulsification kettle. After stirring and dissolving until transparent, add the vinyl monomer and the hydroxy acrylic monomer, and stir at 420 r / min for 30 min to obtain a pre-emulsion.

[0109] S2. Dissolve 0.8 part of initiator in 8 parts of deionized water to form the first initiator solution; dissolve the remaining initiator in 13.4 parts of deionized water to form the second initiator solution; dissolve the oxidant in 13 parts of deionized water to form the oxidant solution; dissolve the reductant in 13 parts of deionized water to form the reductant solution;

[0110] S3. Add a buffer, a non-ionic emulsifier, 261 parts of deionized water and the remaining anionic emulsifier to the reaction kettle. After stirring and heating to 85 °C, simultaneously add the first initiator solution and 6 wt% of the pre-emulsion for an initial reaction for 10 min;

[0111] S4. After the initial reaction is completed, uniformly and continuously add the remaining pre-emulsion and the second initiator solution. After adding for 3 h, keep warm for 1.5 h, cool down to 60 °C, and simultaneously add the oxidant and the reductant. After adding for 0.5 h, keep warm for 0.5 h to obtain a mixture;

[0112] S5. Cool the mixture to below 40 °C, add a neutralizing agent to adjust the pH to 8, filter and discharge to obtain the high-hydroxyl acrylate emulsion.

[0113] The obtained acrylic emulsion has a hydroxyl content of 3%, a viscosity of 3300 mPa·s at 25 °C, and a solid content of 45 wt%.

[0114] Comparative Example 3

[0115] The specific implementation method of this comparative example is the same as that of Example 2, except that the chain transfer agent is n-dodecyl mercaptan.

[0116] The obtained acrylic emulsion has a hydroxyl content of 3%, a viscosity of 3500 mPa·s at 25 °C, and a solid content of 45 wt%.

[0117] Performance Test

[0118] Prepare the acrylate emulsion prepared in each example and comparative example into an anti-rust paint coating. After baking at 80 °C for 2 h and curing at room temperature for 1 day, test the gloss, flash rust inhibition (flash rust point), activation period, water resistance, and salt spray resistance according to HG / T 4761-2014. The test results are shown in Table 1.

[0119] The preparation method of the anti-rust paint coating is as follows:

[0120] a. Add 0.8 part of dispersanttego 760W to 7 parts of deionized water, stir evenly, add 15 parts of titanium dioxide R996, 5 parts of zinc phosphate, and 0.1 part of Tego 902W while stirring. Add zirconium beads and grind at high speed until the fineness is ≤ 25 μm and qualified, then discharge to obtain the color paste;

[0121] b. Add 2 parts of propylene glycol methyl ether acetate to 12 parts of curing agent Bayhydur 2655 and stir evenly to obtain a diluted curing agent;

[0122] c. Add 2 parts of ethylene glycol butyl ether, 2 parts of dipropylene glycol butyl ether and 0.3 parts of BYK346 to 60 parts of acrylic emulsion while stirring, add 28 parts of the color paste after stirring evenly, add 0.2 parts of thickener 0620 after stirring for 5 minutes, continue stirring for 5 minutes, add 14 parts of the diluted curing agent, stir evenly to obtain the anti-rust paint.

[0123] Table 1

[0124]

[0125] As shown in the table, the high-hydroxyl acrylic emulsion prepared in the present application has the advantages of high gloss, good resistance and long activation period compared with the comparative example, and can meet the needs of long-term use.

Claims

1. A high-hydroxyl acrylic emulsion, characterized in that, By weight parts, the preparation raw materials include: 390 - 460 parts of vinyl monomer, 150 - 290 parts of hydroxy acrylic monomer, 12 - 20 parts of anionic emulsifier, 1 - 2 parts of non-ionic emulsifier, 0.5 - 1 part of chain transfer agent, 2 - 4 parts of initiator, 1 - 1.4 parts of buffer, 0.5 - 1 part of oxidant, 0.3 - 0.8 part of reductant, 4 - 6 parts of neutralizer and 728 - 900 parts of deionized water.

2. The high-hydroxyl acrylic emulsion according to claim 1, characterized in that The hydroxy acrylic monomer at least includes a modified hydroxy acrylic monomer.

3. The high-hydroxyl acrylate emulsion according to claim 2, characterized in that, The preparation raw materials of the modified hydroxy acrylic monomer include a monofunctional epoxy diluent, acrylic acid, hydroquinone and triphenylphosphine.

4. The high-hydroxyl acrylic emulsion according to claim 3, wherein The molar ratio of the monofunctional epoxy diluent to acrylic acid is (0.8 - 1.2):1; the hydroquinone accounts for 0.9 - 1.5‰ of the total mass of the monofunctional epoxy diluent and acrylic acid; the triphenylphosphine accounts for 4 - 6‰ of the total mass of the monofunctional epoxy diluent and acrylic acid.

5. The high-hydroxyl acrylate emulsion according to claim 3, wherein, The monofunctional epoxy diluent is selected from at least one of C 12-14 alkyl glycidyl ether, butyl glycidyl ether, benzyl glycidyl ether, and phenyl glycidyl ether.

6. The high-hydroxyl acrylic emulsion according to claim 1, characterized in that, The vinyl monomer is selected from one or more of styrene, n-butyl acrylate, methyl methacrylate, ethyl acrylate, isooctyl methacrylate, isooctyl acrylate, acrylic acid, methacrylic acid, acrylamide, methacrylamide, ethylene urea ethoxy ester methacrylate or acrylic acid phosphate.

7. The high-hydroxyl acrylate emulsion according to claim 1, characterized in that, The chain transfer agent includes mercaptoethanol.

8. A method for synthesizing a high-hydroxyl acrylic emulsion according to any one of claims 1-7, characterized in that, It includes the following steps: S1. Add 420 - 580 parts of deionized water and 30 - 75wt% of anionic emulsifier into a pre-emulsification kettle. After stirring and dissolving until transparent, add vinyl monomer and hydroxy acrylic monomer, and stir for 30 - 60 min to obtain a pre-emulsion. S2. Dissolve 30 - 35wt% of initiator in 6 - 9 parts of deionized water to form a first initiator solution; dissolve the remaining initiator in 10 - 15 parts of deionized water to form a second initiator solution; dissolve the oxidant in 11 - 14 parts of deionized water to form an oxidant solution; dissolve the reductant in 11 - 14 parts of deionized water to form a reductant solution. S3. Add buffer, non-ionic emulsifier, the remaining deionized water and the remaining anionic emulsifier into a reaction kettle. After stirring and heating to 80 - 90 °C, add the first initiator solution and 3 - 10wt% of the pre-emulsion for the initial reaction at the same time. S4. After the initial reaction ends, add the remaining pre-emulsion and the second initiator solution dropwise at a constant speed at the same time. After dropping, keep warm for 1 - 2 h, cool down to 55 - 75 °C, and add the oxidant solution and the reductant solution dropwise at the same time. After dropping, keep warm for 0.5 - 1 h to obtain a mixture. S5. Cool the mixture to below 40 °C, add a neutralizer to adjust the pH to 7 - 9, filter and discharge to obtain the high-hydroxy acrylate emulsion.

9. The synthesis method of the high-hydroxyl acrylic emulsion according to claim 8, characterized in that, The time of the initial reaction in step S3 is 10 - 15 min.

10. The synthesis method of the high-hydroxyl acrylic emulsion according to claim 8, characterized in that, In step S4, the dropping time of the remaining pre-emulsion and the second initiator solution is 3 - 3.5 h; the dropping time of the oxidant solution and the reductant solution is 0.5 - 1 h.

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