Water-based hydroxyl acrylic acid dispersion and preparation method thereof

Abstract

The invention relates to a water-based hydroxy acrylic dispersion and a preparation method thereof, and relates to the technical field of paints.The preparation method comprises the steps that under inert atmosphere protection, a priming solvent is heated to the specified temperature, a first mixed solution is added, and the mixture is dispersed uniformly and reacts sufficiently; adding the second mixed solution and the neutralizer, uniformly dispersing again, and fully reacting; and adding a third mixed solvent, uniformly dispersing, adding water, and filtering to obtain the water-based hydroxy acrylic dispersion. Compared with the prior art, the prepared water-based hydroxyl acrylic dispersion has the advantages that the solid content of the product is increased while the annual length is not greatly increased, and the obtained water-based hydroxyl acrylic dispersion is low in VOC (volatile organic compound).

Description

Technical Field

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

[0002] In the context of increasingly serious environmental problems, in order to make up for the ecological shortcomings, environmental protection-related laws and regulations are becoming more and more perfect. The country has imposed strict restrictions on the emission of volatile organic compounds (VOC) in coatings, and the market demand for environmentally friendly coatings is gradually increasing. Environmentally friendly coatings mainly include water-based coatings, powder coatings, radiation-cured coatings and high-solid coatings, among which the research on water-based coatings is the most extensive. Among water-based coatings, the coatings made of two-component water-based hydroxylated acrylic dispersions have good appearance and excellent performance, and are widely used in engineering machinery, automotive industry, wood products and other fields.

[0003] Common water-based hydroxylated acrylic dispersions usually add monomer solutions in two steps. The first step is a monomer with a higher glass transition temperature and is more hydrophobic. The second step is a monomer with a lower glass transition temperature and is hydrophilic, containing an acid. After the polymerization is completed, it is neutralized with an organic base. After neutralization, water is added for high-speed dispersion.

[0004] The aqueous hydroxy acrylic dispersion obtained by the above method has the disadvantages of high VOC content, high viscosity, low solid content and instability. In order to reduce viscosity and increase solid content. CN 111116812 A introduces a certain amount of steric hindrance monomers to reduce the viscosity of the resin during neutralization and emulsification, and synthesizes a dispersion with a core-shell structure; CN 109456442A uses a molecular weight regulator α-methylstyrene linear dimer as a primer solvent to reduce the VOC of the product. CN 111116812 A and CN 109456442 A need to significantly increase its viscosity while increasing the solid content of the hydroxy acrylic dispersion. Wang Zhuoyan et al. (Wang Zhuoyan, Xu Guowei, Gao Kui, et al. Preparation of high solid content hydroxy acrylic dispersion by in-situ polymerization and study of its properties [J]. Coatings Industry, 2021, 51 (8): 1-8) synthesized an aqueous hydroxy acrylic dispersion with high solid content by combining in-situ polymerization, and the VOC content was too high. Summary of the invention

[0005] The purpose of the present invention is to provide an aqueous hydroxy acrylic acid dispersion and a preparation method thereof in order to overcome at least one of the defects of the prior art.

[0006] Compared with CN 111116812 A and CN 109456442 A, the present invention adopts a three-step method instead of a two-step method, which can increase the solid content of the hydroxyl acrylic acid dispersion without significantly increasing the viscosity of the hydroxyl acrylic acid dispersion. Compared with Wang Zhuoyan's work, the present invention uses dodecanethiol and tert-butyl glycidyl alcohol as primer solvents, and the VOC of the dispersion can be significantly reduced.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] One of the purposes of the present invention is an aqueous hydroxy acrylic dispersion, comprising the following raw materials: a primer solvent, a first mixed solution, a second mixed solution, a third mixed solution, a neutralizer and water in a mass ratio of (3-20):(10.5-32.2):(11.5-42.2):(10.5-32.2);

[0009] Wherein, the first mixed solution, the second mixed solution and the third mixed solution all contain polyheterocyclic acrylate monomers;

[0010] The second mixed solution contains a hydrophilic monomer.

[0011] In one embodiment of the present invention, the raw materials of the dispersion include, by weight:

[0012]

[0013] In one embodiment of the present invention, the first mixed solution, the second mixed solution and the third mixed solution all contain

[0014]

[0015] The first mixed solution and the second mixed solution further contain initiator A;

[0016] The third mixed solution further contains initiator B;

[0017] The second mixed solution also contains a carboxyl group-containing monomer.

[0018] In one embodiment of the present invention, the primer solvent comprises dodecanethiol and tert-butyl glycidyl carbonate in a mass ratio of (3-15):(5-15).

[0019] Preferably, the primer solvent comprises dodecanethiol and tert-butyl glycidyl carbonate in a mass ratio of (5-10):(5-8).

[0020] In one embodiment of the present invention:

[0021] The hydroxyl-containing monomer includes any one or more of hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate or hydroxyethyl acrylate;

[0022] The methacrylate monomer includes at least one of methyl methacrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, dimethylaminopropyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

[0023] The vinyl monomer is a vinyl aromatic compound;

[0024] The polyheterocyclic acrylate monomers include one or more of isobornyl acrylate, isobornyl methacrylate and polyheterocyclic acrylate monomers;

[0025] The carboxyl group-containing monomer includes any one or more of acrylic acid, methacrylic acid or fumaric acid.

[0026] In one embodiment of the present invention:

[0027] The methacrylate monomer is any one or more of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate or isobutyl methacrylate.

[0028] The vinyl monomer is styrene;

[0029] The polyheterocyclic acrylate monomer is isobornyl acrylate;

[0030] The carboxyl group-containing monomer is methacrylic acid.

[0031] In one embodiment of the present invention:

[0032] The initiators A and B include any one or more of tert-butyl peroxyacetate, tert-amyl peroxyacetate, di-tert-butyl peroxide, di-tert-amyl peroxide, benzoyl peroxide, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexyl tert-butyl peroxide, ammonium persulfate, tert-amyl peroxide-2-ethylhexyl, diisopropylbenzene peroxide or azobisisobutyronitrile.

[0033] In one embodiment of the present invention, the initiator A is di-tert-amyl peroxide or di-tert-butyl peroxide; the initiator B is ammonium persulfate or azobisisobutyronitrile.

[0034] In one embodiment of the present invention, the neutralizing agent is N,N-dimethylethanolamine.

[0035] The second object of the present invention is a method for preparing the aqueous hydroxylated acrylic dispersion as described above, characterized in that it comprises the following steps:

[0036] Under the protection of an inert atmosphere, the primer solvent is heated to a specified temperature, the first mixed solution is added, and the mixture is dispersed evenly and reacted sufficiently; the second mixed solution and a neutralizer are added, and the mixture is dispersed evenly again and reacted sufficiently; the third mixed solvent is added, the mixture is dispersed evenly, and water is added. After filtering, an aqueous hydroxy acrylic dispersion is obtained.

[0037] In a preferred embodiment of the present invention, the preparation method of the aqueous hydroxylated acrylic dispersion comprises the following steps:

[0038] Under nitrogen protection, add the primer solvent into the reactor, heat it to 160, slowly add the first mixed solution within 2-3 hours and keep it warm for half an hour; then slowly add the second mixed solution within 1.5 hours and keep it warm for 1 hour, then cool it down to 70℃ and add the neutralizer, after it is evenly dispersed, cool it down to 70℃ and add the third mixed solution, add deionized water after it is evenly dispersed, heat it to 90-100℃ and keep it warm for 2 hours, then filter it to get the product.

[0039] Compared with the prior art, the present invention uses dodecanethiol and tert-butyl glycidyl alcohol as primer solvents to significantly reduce the VOC of the product, and introduces in-situ polymerization in a three-step method instead of a two-step method. In the first two steps of solution polymerization, a core-shell structure synthesis method is adopted. While increasing the solid content of the product, the newly added monomer is coated inside the dispersion particles, and the hydroxyl group is difficult to be exposed, so the final viscosity of the acrylic dispersion will not be increased. The introduction of polyheterocyclic acrylate monomers can further reduce the viscosity of the product, and overcomes the shortcomings of common synthesis methods, such as: due to the high final viscosity, it is impossible to prepare a high-solid dispersion, the VOC is large, etc., and provides a new idea for improving the performance of water-based hydroxy acrylic dispersions. DETAILED DESCRIPTION

[0040] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0041] A water-based hydroxy acrylic dispersion comprises the following raw materials: a primer solvent, a first mixed solution, a second mixed solution, a third mixed solution, a neutralizer and water in a mass ratio of (3-20):(10.5-32.2):(11.5-42.2):(10.5-32.2);

[0042] Wherein, the first mixed solution, the second mixed solution and the third mixed solution all contain polyheterocyclic acrylate monomers;

[0043] The second mixed solution contains a hydrophilic monomer.

[0044] Specifically, the raw materials of the dispersion include, by weight:

[0045]

[0046] The first mixed solution, the second mixed solution and the third mixed solution all contain

[0047]

[0048] The first mixed solution and the second mixed solution further contain initiator A;

[0049] The third mixed solution further contains initiator B;

[0050] The second mixed solution also contains a carboxyl group-containing monomer.

[0051] The primer solvent comprises dodecanethiol and tert-butyl glycidyl carbonate in a mass ratio of (3-15):(5-15). Preferably, the primer solvent comprises dodecanethiol and tert-butyl glycidyl carbonate in a mass ratio of (5-10):(5-8).

[0052] The hydroxyl-containing monomer includes any one or more of hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate or hydroxyethyl acrylate; the methacrylate monomer includes at least one of methyl methacrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, dimethylaminopropyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, polypropylene glycol dimethacrylate and trimethylolpropane trimethacrylate; the vinyl monomer is a vinyl aromatic compound; the polyheterocyclic acrylate monomer includes one or more of isobornyl acrylate, isobornyl methacrylate and polyheterocyclic acrylate monomers; the carboxyl-containing monomer includes any one or more of acrylic acid, methacrylic acid or fumaric acid.

[0053] Preferably, the methacrylate monomer is any one or more of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate or isobutyl methacrylate; the vinyl monomer is styrene; the polyheterocyclic acrylate monomer is isobornyl acrylate; and the carboxyl-containing monomer is methacrylic acid.

[0054] The initiators A and B include any one or more of tert-butyl peroxyacetate, tert-amyl peroxyacetate, di-tert-butyl peroxide, di-tert-amyl peroxide, benzoyl peroxide, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexyl tert-butyl peroxide, ammonium persulfate, tert-amyl peroxide-2-ethylhexyl, diisopropylbenzene peroxide or azobisisobutyronitrile. Preferably, the initiator A is di-tert-amyl peroxide or di-tert-butyl peroxide; the initiator B is ammonium persulfate or azobisisobutyronitrile.

[0055] Example 1

[0056] 1. The formula of this embodiment is as follows by weight:

[0057] Primer solvent: 5 parts of dodecanethiol and 5 parts of tert-butyl ester;

[0058] First mixed solution:

[0059]

[0060] Second mixed solution:

[0061]

[0062] The third mixed solution:

[0063]

[0064] Neutralizer: 4 parts of N,N-dimethylethanolamine;

[0065] and 35 parts of deionized water.

[0066] 2. The preparation process is as follows:

[0067] Under nitrogen protection, add the primer solvent, raise the temperature to 160°C, slowly add the first mixed solution within 2 hours and keep warm for half an hour, then slowly add the second mixed solution within 1.5 hours and keep warm for 1 hour, then cool to 70°C and add the neutralizer.

[0068] After being evenly dispersed, the temperature is lowered to 70°C and the third mixed solution is added. After being evenly dispersed, 35 parts of deionized water are added, and the temperature is raised to 90-100°C and kept for 2 hours, and then the product can be filtered.

[0069] Example 2

[0070] 1. The formula of this embodiment is as follows by weight:

[0071] Primer solvent: 5 parts of dodecanethiol and 5 parts of tert-butyl ester;

[0072] First mixed solution:

[0073]

[0074]

[0075] Second mixed solution:

[0076]

[0077] The third mixed solution:

[0078]

[0079] Neutralizer: 4 parts of N,N-dimethylethanolamine;

[0080] and 35 parts of deionized water.

[0081] 2. The preparation process is as follows:

[0082] Under nitrogen protection, add the primer solvent, raise the temperature to 150°C, slowly add the first mixed solution within 3 hours and keep warm for half an hour, then slowly add the second mixed solution within 1.5 hours and keep warm for 1 hour, then cool to 70°C and add the neutralizer.

[0083] After being evenly dispersed, the temperature is lowered to 70°C and the third mixed solution is added. After being evenly dispersed, 35 parts of deionized water are added, and the temperature is raised to 90-100°C and kept for 2 hours. The product can then be filtered to obtain the product.

[0084] Example 3

[0085] 1. The formula of this embodiment is as follows by weight:

[0086] Primer solvent: 5 parts of dodecanethiol and 5 parts of tert-butyl ester;

[0087] First mixed solution:

[0088]

[0089]

[0090] Second mixed solution:

[0091]

[0092] The third mixed solution:

[0093]

[0094] Neutralizer: 4 parts of N,N-dimethylethanolamine;

[0095] and 38 parts of deionized water.

[0096] 2. The preparation process is as follows:

[0097] Under nitrogen protection, add the primer solvent, raise the temperature to 150°C, slowly add the first mixed solution within 3 hours and keep warm for half an hour, then slowly add the second mixed solution within 1.5 hours and keep warm for 1 hour, then cool to 70°C, add 4 parts of N,N-dimethylethanolamine, and add the third mixed solution after uniform dispersion. After uniform dispersion, add 38 parts of deionized water, raise the temperature to 90-100°C and keep warm for 2 hours, and then filter to obtain the product.

[0098] Comparative Example 1:

[0099] By weight, under nitrogen protection, add 5 parts of dodecanethiol and 5 parts of tert-butyl carbonate, raise the temperature to 160°C, slowly add the first mixed solution (including 7 parts of hydroxyethyl methacrylate, 2 parts of butyl acrylate, 10 parts of methyl methacrylate, 4 parts of styrene, 1 part of acrylic acid, 0.6 parts of di-tert-butyl peroxide) within 3 hours and keep warm for half an hour, then slowly add the second mixed solution (including 5 parts of hydroxyethyl methacrylate, 1 part of acrylic acid, 10 parts of butyl acrylate, 5 parts of methyl methacrylate, 4 parts of styrene, 0.6 parts of di-tert-butyl peroxide) within 1.5 hours and keep warm for 1 hour, then cool to 70°C and add 4 parts of N,N-dimethylethanolamine, add 45 parts of deionized water after uniform dispersion and keep warm for 2 hours, then filter to obtain the product.

[0100] Comparative Example 2:

[0101] According to weight, 5 parts of dodecanethiol and 5 parts of tert-butyl carbonate were added under nitrogen protection, the temperature was raised to 150°C, and the first mixed solution (including 5 parts of hydroxyethyl methacrylate, 2 parts of butyl acrylate, 2 parts of isobornyl methacrylate, 5 parts of methyl methacrylate, 4 parts of styrene, 0.6 parts of di-tert-butyl peroxide, and 1 part of acrylic acid) was slowly added within 3 hours and kept warm for half an hour, and then the second mixed solution (including 5 parts of hydroxyethyl methacrylate, 1 part of acrylic acid, 2 parts of isobornyl methacrylate, 10 butyl acrylate, 5 parts of methyl methacrylate, 4 parts of styrene, 0.6 parts of di-tert-butyl peroxide) are slowly added and kept warm for 1 hour, then the temperature is lowered to 70°C and 4 parts of N,N-dimethylethanolamine are added. After uniform dispersion, the temperature is lowered to 70°C and the third mixed solution (including 2 parts of hydroxyethyl methacrylate, 2 parts of isobornyl methacrylate, 5 parts of methyl methacrylate, and 2 parts of azobisisobutyronitrile) is added. After uniform dispersion, 35 parts of deionized water are added, the temperature is raised to 90-100°C and kept warm for 2 hours, and then the product can be filtered.

[0102] Among the 5 parts of aqueous hydroxy acrylic dispersions obtained above, Comparative Example 1 adopts a two-step method, and the obtained product has a higher viscosity and a lower solid content, which shows that replacing the two-step method with a three-step method can effectively increase the solid content of the product, and introducing a polyheterocyclic acrylate monomer can effectively reduce the viscosity of the product. The viscosity of Comparative Example 2 is the largest and most unstable, which shows that in the three-step synthesis method, the addition of a hydrophilic monomer in the second step and the use of tert-butyl glycidyl carbonate and dodecyl mercaptan as primer solvents can greatly reduce the viscosity of the product and improve the stability. The viscosity of the embodiment is relatively low, the measured solid content is high, and the stability is good, which shows that the present invention uses dodecyl mercaptan and tert-butyl glycidyl carbonate as primer solvents, combines the two-step core-shell structure method with the in-situ polymerization three-step method, and introduces a polyheterocyclic acrylate monomer, which can effectively increase the solid content of the product, reduce the viscosity, enhance the stability of the product, and reduce the solvent content of the product.

[0103] Table 1 Viscosity, measured solid content and stability of Examples 1-3 and Comparative Examples 1-2

[0104]

[0105] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. An aqueous hydroxylated acrylic dispersion, characterized in that: The method comprises the following raw materials: a primer solvent, a first mixed solution, a second mixed solution, a third mixed solution, a neutralizer and water in a mass ratio of (3-20):(10.5-32.2):(11.5-42.2):(10.5-32.2); Wherein, the first mixed solution, the second mixed solution and the third mixed solution all contain polyheterocyclic acrylate monomers; The second mixed solution contains a hydrophilic monomer.

2. The aqueous hydroxylated acrylic dispersion according to claim 1, characterized in that: By weight, the raw materials of the dispersion include:

3. An aqueous hydroxylated acrylic dispersion according to claim 1 or 2, characterized in that: By weight, the first mixed solution, the second mixed solution and the third mixed solution all contain The first mixed solution and the second mixed solution further contain initiator A; The third mixed solution further contains initiator B; The second mixed solution also contains a carboxyl group-containing monomer.

4. The aqueous hydroxylated acrylic dispersion according to claim 1, characterized in that: The primer solvent comprises dodecanethiol and tert-butyl glycidyl carbonate in a mass ratio of (3-15):(5-15).

5. The aqueous hydroxylated acrylic dispersion according to claim 4, characterized in that: The primer solvent comprises dodecanethiol and tert-butyl glycidyl carbonate in a mass ratio of (5-10):(5-8).

6. The aqueous hydroxylated acrylic dispersion according to claim 3, characterized in that: The hydroxyl-containing monomer includes any one or more of hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl methacrylate or hydroxyethyl acrylate; The methacrylate monomer includes at least one of methyl methacrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, dimethylaminopropyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, and trimethylolpropane trimethacrylate; The vinyl monomer is a vinyl aromatic compound; The polyheterocyclic acrylate monomers include one or more of isobornyl acrylate, isobornyl methacrylate and polyheterocyclic acrylate monomers; The carboxyl group-containing monomer includes any one or more of acrylic acid, methacrylic acid or fumaric acid.

7. The aqueous hydroxylated acrylic dispersion according to claim 6, characterized in that: The methacrylate monomer is any one or more of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate or isobutyl methacrylate; The vinyl monomer is styrene; The polyheterocyclic acrylate monomer is isobornyl acrylate; The carboxyl group-containing monomer is methacrylic acid.

8. The aqueous hydroxylated acrylic dispersion according to claim 3, characterized in that: The initiators A and B include any one or more of tert-butyl peroxyacetate, tert-amyl peroxyacetate, di-tert-butyl peroxide, di-tert-amyl peroxide, benzoyl peroxide, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexyl tert-butyl peroxide, ammonium persulfate, tert-amyl peroxide-2-ethylhexyl, diisopropylbenzene peroxide or azobisisobutyronitrile.

9. The aqueous hydroxylated acrylic dispersion according to claim 8, characterized in that: The initiator A is di-tert-amyl peroxide or di-tert-butyl peroxide; the initiator B is ammonium persulfate or azobisisobutyronitrile.

10. A method for preparing an aqueous hydroxy acrylic dispersion according to any one of claims 1 to 9, characterized in that: The steps include: Under the protection of an inert atmosphere, the primer solvent is heated to a specified temperature, the first mixed solution is added, and the mixture is dispersed evenly and reacted sufficiently; the second mixed solution and a neutralizer are added, and the mixture is dispersed evenly again and reacted sufficiently; the third mixed solvent is added, the mixture is dispersed evenly, and water is added. After filtering, an aqueous hydroxy acrylic dispersion is obtained.

Images