Aqueous secondary dispersions containing copolymer p, methods of making and using the same

Abstract

The application discloses an aqueous secondary dispersion containing a copolymer P, which is synthesized from the following components: 1) a hydroxyl-containing hydrophobic polymer containing the following components as structural unit monomers: A1 hydroxyl-containing monomer, B1 acrylic ester monomer and / or vinylic monomer, and 2) a hydroxyl-containing hydrophilic polymer containing the following components as structural unit monomers: A2 hydroxyl-containing monomer, B2 acrylic ester monomer and / or vinylic monomer with a Tg of a homopolymer greater than 80 DEG C, C acrylic ester monomer with a Tg of a homopolymer below 80 DEG C, and D carboxyl-containing monomer. The dispersion has a high bubble-free film thickness, and other properties such as hardness and resistance are not obviously lost; meanwhile, the dispersion has good weather resistance and can tolerate low-humidity, especially high-temperature low-humidity construction environment. The application further discloses a preparation method and application of the dispersion.

Description

Technical Field

[0001] This invention relates to the field of coating technology. More specifically, it relates to an aqueous secondary dispersion containing copolymer P, its preparation method, and its application. Background Technology

[0002] In recent years, with increasingly stringent national environmental protection policies, water-based coatings have become a research hotspot in the coatings industry due to their advantages such as being non-toxic, non-flammable, environmentally friendly, and energy-saving. Among these water-based coatings, water-based two-component systems combining hydroxyl acrylate dispersions and isocyanate curing agents are widely used in industrial coatings for wood and metal products due to their excellent properties such as high gloss, good weather resistance, and color and gloss retention. In some applications, they can even rival oil-based systems, showing a very promising future.

[0003] However, in practical applications, especially in high-temperature, low-humidity construction environments, when the paint film thickness reaches a certain level, bubbles or pinholes often appear on the surface, severely affecting the appearance and performance of the paint film. This is because, during thick paint film application, gases introduced during stirring and gases such as carbon dioxide generated from the reaction of isocyanate groups with water cannot all escape, resulting in defects. Bubbles are visual defects left by gases encountering paint film curing as they penetrate the surface. In such cases, we typically describe the paint system as having poor application properties, severely affecting its appearance, and unusable on-site. Using a sample with gradient film thickness spraying can determine the bubble-free film thickness of the resin and corresponding paint. As the film thickness increases, the ability for gas escape gradually weakens until pinholes and bubbles appear; the film thickness in this area is the bubble-free film thickness of the system. Provided other performance characteristics are ensured, a higher bubble-free film thickness is better.

[0004] Currently, there are several related patent reports on improving the bubble-free film thickness of resins to ensure the applicability of the corresponding coatings. CN 101622309A discloses a method for improving the bubble-free film thickness of resins. This patent improves the applicability of coatings by introducing high-boiling-point non-polar solvents into the formulation. However, the introduced high-boiling-point solvents usually cannot evaporate completely under baking conditions, especially low-temperature curing conditions, thus significantly reducing the hardness and toughness of the paint film, which severely limits the practical application of this method.

[0005] In view of this, it is necessary to provide a hydroxy acrylate aqueous dispersion with excellent application properties, which has a high bubble-free film thickness while maintaining other properties such as hardness and toughness without significant loss, in order to solve the problems existing in the prior art. Summary of the Invention

[0006] The first objective of this invention is to provide an aqueous secondary dispersion containing copolymer P, which has a high bubble-free film thickness while maintaining other properties such as hardness and toughness without significant loss; at the same time, it has good weather resistance and can withstand construction environments with low humidity, especially high temperature and low humidity.

[0007] A second objective of this invention is to provide a method for preparing an aqueous secondary dispersion containing copolymer P.

[0008] A third objective of this invention is to provide a water-based coating.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] An aqueous secondary dispersion containing copolymer P, characterized in that copolymer P is synthesized from the following components:

[0011] 1) Hydrophobic polymers containing the following components as structural unit monomers:

[0012] A1 contains a hydroxyl monomer.

[0013] B1 acrylate monomers and / or ethylene monomers, and

[0014] 2) Hydrophilic polymers containing the following components as structural unit monomers:

[0015] A2 contains a hydroxyl monomer.

[0016] B2 homopolymers have a Tg greater than that of acrylate monomers and / or vinyl monomers at 80℃.

[0017] The Tg of C homopolymers is below 80℃ for acrylate monomers.

[0018] D contains a carboxyl monomer.

[0019] Furthermore, in the copolymer P, the content of the hydroxyl-containing hydrophobic polymer and the hydroxyl-containing hydrophilic polymer is as follows:

[0020] Hydrophobic polymers containing hydroxyl groups 50-90 wt%;

[0021] Hydrophilic polymers containing hydroxyl groups, 10-50 wt%.

[0022] Furthermore, the copolymer P is synthesized from the following components:

[0023] 1) Hydrophobic polymers containing the following components as structural unit monomers:

[0024] A1 contains 10-30 wt% hydroxyl monomers.

[0025] B1 acrylate monomers and / or vinyl monomers 70-90 wt%, and

[0026] 2) Hydrophilic polymers containing the following components as structural unit monomers:

[0027]

[0028] Furthermore, the solid content of the aqueous secondary dispersion is 30%-70%, preferably 40%-60%.

[0029] Furthermore, the molecular weight of the copolymer P is 4000-10000 g / mol, preferably 5000-8000 g / mol.

[0030] Furthermore, the structural unit monomers of hydroxyl-containing hydrophobic polymers and / or hydroxyl-containing hydrophilic polymers also contain monomer Y;

[0031] Among them, monomer Y is an acrylate monomer prepared by ring opening of carboxyl-containing monomer and glycidyl tert-carbonate, and the content of monomer Y accounts for 2-10 wt% of the total content of each component of copolymer P.

[0032] Furthermore, the structural formula of the monomer Y is shown in Equation I below:

[0033]

[0034] R1 and R2 are each independently selected from alkyl groups, and the total number of carbon atoms in R1 and R2 is 7.

[0035] Furthermore, A1 and A2, the hydroxyl-containing monomers, are each independently selected from at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate.

[0036] Furthermore, the D-containing carboxyl monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid.

[0037] Further, the B1 acrylate monomer is selected from at least one of methyl methacrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, coconut oleate methacrylate, octadecyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, glycidyl methacrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate.

[0038] Furthermore, the B1 ethylene monomer is selected from at least one of vinyl acetate, dichloroethylene, styrene, acrylonitrile, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and divinylbenzene.

[0039] Furthermore, the B2 acrylate monomer and / or ethylene monomer are selected from one or more of methyl methacrylate, styrene, cyclic methacrylate, and isobornyl methacrylate.

[0040] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0041] A method for preparing an aqueous secondary dispersion containing copolymer P includes the following steps:

[0042] Under a nitrogen atmosphere, monomers and initiators that form hydroxyl-containing hydrophobic polymers are added to the solvent at the reaction temperature, followed by a first heating.

[0043] Add structural unit monomers and initiators to form hydroxyl-containing hydrophilic polymers, and perform a second heat preservation;

[0044] Cool down, add a neutralizing agent, and perform a third insulation process;

[0045] Add deionized water for emulsification, and then perform a fourth heat treatment.

[0046] Filtration yields the aqueous secondary dispersion containing copolymer P.

[0047] To achieve the third objective mentioned above, the present invention also provides an aqueous coating comprising an aqueous secondary dispersion containing copolymer P as described in the first objective above.

[0048] Furthermore, the water-based coating also contains a crosslinking agent.

[0049] Furthermore, the crosslinking agent is selected from one or more of hydrophilic polyisocyanates and hydrophobic polyisocyanates.

[0050] The beneficial effects of this invention are as follows:

[0051] The aqueous secondary dispersion provided by this invention features a specially designed hydroxyl-containing hydrophilic polymer (dispersion shell polymer) containing high-Tg acrylate monomers and / or vinyl monomers. When used in the preparation of waterborne coatings, the reduced chain segment movement during early crosslinking with the curing agent slows the reaction rate, leading to a decrease in coating viscosity during solvent evaporation. This creates conditions for bubble release, ultimately resulting in a significant improvement in the bubble-free film thickness and application properties of the resin. Furthermore, as curing progresses, the hydrophilic polymer chains gradually thaw under baking and begin to move, participating in the curing process. Therefore, the hardness and various resistance properties of the paint film are not compromised. Additionally, the preferred addition of monomer Y in the aqueous secondary dispersion increases the distance between polymeric segments, which also helps reduce polymer viscosity and improve the bubble-free film thickness.

[0052] The water-based coating provided by this invention, which is obtained by combining the water-based secondary dispersion with the water-based diisocyanate curing agent, has excellent application properties, high gloss, high hardness, and excellent weather resistance. Detailed Implementation

[0053] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0054] According to a specific embodiment of the present invention, an aqueous secondary dispersion containing copolymer P is provided so that waterborne coatings can improve the thickness of the bubble-free film while maintaining good workability, high gloss, hardness and good weather resistance.

[0055] This invention reveals that, through a unique design of the polymer segments in the copolymer of this aqueous secondary dispersion, the prepared dispersion is highly suitable for preparing coatings with high bubble-free film thickness and significantly improved application performance. In this invention, the aqueous secondary dispersion is an acrylic dispersion, wherein the copolymer P is synthesized from the following components:

[0056] 1) Hydrophobic polymers containing hydroxyl groups (P1) as structural unit monomers:

[0057] A1 contains a hydroxyl monomer.

[0058] B1 acrylate monomers and / or ethylene monomers, and

[0059] 2) Hydroxyl-containing hydrophilic polymers (P2) containing the following components as structural unit monomers:

[0060] A2 contains a hydroxyl monomer.

[0061] B2 homopolymers have a Tg greater than that of acrylate monomers and / or vinyl monomers at 80℃.

[0062] The Tg of C homopolymers is below 80℃ for acrylate monomers.

[0063] D contains a carboxyl monomer.

[0064] In a preferred example, the copolymer P is synthesized from the following components:

[0065] 1) A hydroxyl-containing hydrophobic polymer, wherein the hydroxyl-containing hydrophobic polymer contains the following components as structural unit monomers, based on the total mass of the structural unit monomers forming the hydroxyl-containing hydrophobic polymer:

[0066] A1 contains 10-30 wt% hydroxyl monomers.

[0067] B1 acrylate monomers and / or vinyl monomers 70-90 wt%, and

[0068] 2) A hydroxyl-containing hydrophilic polymer, wherein the hydroxyl-containing hydrophilic polymer contains the following components as structural unit monomers, based on the total mass of the structural unit monomers forming the hydroxyl-containing hydrophilic polymer:

[0069]

[0070] Typically, acrylic dispersions contain at least two polymer segments: a hydrophilic polymer and a hydrophobic polymer. After neutralization and emulsification, the hydrophilic polymer acts as an emulsifier, encapsulating the hydrophobic polymer within the dispersion in water. Conventional designs typically employ a hard-outer-hard approach. Currently, there is almost no research on the glass transition temperature (TVT) of the hydrophilic polymer, i.e., the shell polymer of the dispersion. We unexpectedly discovered that when the monomers of the hydroxyl-containing hydrophilic polymer contain a specific amount of acrylate monomers and / or vinyl monomers with a Tg greater than 80°C of homopolymers, the bubble-free film thickness of the resin is significantly improved. Simultaneously, the hardness and weather resistance (especially in low-humidity and high-temperature-low-humidity environments) are also good.

[0071] In a preferred embodiment, the Tg of the homopolymer of the B2 acrylate monomer and / or vinyl monomer is greater than 80°C. Under these conditions, the improvement in the bubble-free film thickness, hardness, and weather resistance of the resin is even better.

[0072] For example, the B2 acrylate monomer and / or ethylene monomer are selected from one or more of methyl methacrylate, styrene, cyclic methacrylate, and isobornyl methacrylate.

[0073] The hydroxyl-containing monomers suitable for A1 and A2 may include, but are not limited to, at least one selected from hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Furthermore, the hydroxyl-containing monomers in A1 and A2 may be the same or different.

[0074] It should be noted that in this invention, hydroxyethyl methacrylate refers to hydroxyethyl methacrylate or hydroxyethyl acrylate. Other substances with this notation have the same or similar meaning and will not be elaborated upon here.

[0075] For example, the B1 acrylate monomer is selected from at least one of methyl methacrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, coconut oleate methacrylate, octadecyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, glycidyl methacrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate.

[0076] For example, the B1 ethylene monomer is selected from at least one of vinyl acetate, dichloroethylene, styrene, acrylonitrile, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and divinylbenzene.

[0077] In a preferred example, the D-carboxyl-containing monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid.

[0078] In a preferred example, the B2 acrylate monomer and / or ethylene monomer are selected from one or more of methyl methacrylate, styrene, cyclomethacrylate (e.g., cyclohexyl methacrylate), and isobornyl methacrylate.

[0079] For example, the C acrylate monomer is selected from at least one of methyl acrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, coconut oleate methacrylate, octadecyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, glycidyl methacrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate.

[0080] In a preferred embodiment, the structural unit monomers of the hydroxyl-containing hydrophobic polymer and / or hydroxyl-containing hydrophilic polymer further contain monomer Y; wherein monomer Y is an acrylate monomer prepared by ring-opening of a carboxyl-containing monomer and glycidyl tert-carbonate. It has been found in this invention that the introduction of monomer Y can reduce the viscosity of the polymer and also help improve the bubble-free film thickness of coatings containing this aqueous secondary dispersion. While significantly improving the resin's applicability (improved bubble-free film thickness), the basic properties of the paint film (especially hardness and durability) remain good.

[0081] Suitable monomer Y is an acrylate monomer prepared by ring-opening of a carboxyl-containing monomer and glycidyl tert-carbonate, wherein the carboxyl-containing monomer is preferably methacrylic acid and acrylic acid. Preferably, the ring-opening reaction is carried out at 100-150°C with the addition of a polymerization inhibitor.

[0082] Furthermore, the preparation method of monomer Y includes the following steps:

[0083] 200-300 parts of glycidyl tert-carbonate, 60-80 parts of acrylic acid, and 0-1 parts of p-hydroxyanisole are mixed and added to a reaction vessel and heated to 100-160℃. The acid value is then tested until it is less than 1 mg KOH / g, and the mixture is cooled to room temperature before being discharged.

[0084] The preferred structural formula for monomer Y is shown in Equation I below:

[0085]

[0086] In this process, R1 and R2 are each independently selected from alkyl groups, and the total number of carbon atoms in R1 and R2 is 7. Under these preferred conditions, the resulting coating containing this aqueous secondary dispersion exhibits a higher bubble-free film thickness and more significant improvements in hardness and weather resistance.

[0087] The content of monomer Y is preferably 2-10 wt% of the total content of all components of copolymer P. For example, the content of monomer Y includes, but is not limited to, 2-8 wt%, 4-10 wt%, 4-8 wt% of the total content of all components of copolymer P.

[0088] In a preferred example, the copolymer P contains the following amounts of hydroxyl-containing hydrophobic polymer and hydroxyl-containing hydrophilic polymer:

[0089] Hydrophobic polymers containing hydroxyl groups 50-90 wt%;

[0090] Hydrophilic polymers containing hydroxyl groups, 10-50 wt%.

[0091] In this embodiment, the molecular weight of the suitable copolymer P is 4000-10000 g / mol, preferably 5000-8000 g / mol.

[0092] In this embodiment, the solid content of the suitable aqueous secondary dispersion is 30-70%, preferably 40-60%.

[0093] Another specific embodiment of the present invention provides a method for preparing the aqueous secondary dispersion containing copolymer P as described above, comprising the following steps:

[0094] Under a nitrogen atmosphere, the structural unit monomers (i.e. components A1 and B1) and the initiator that form the hydroxyl-containing hydrophobic polymer are added to the solvent at the reaction temperature, and the polymerization temperature is maintained for the first time.

[0095] Add the structural unit monomers (i.e. components A2, B2, C and D) that form hydroxyl-containing hydrophilic polymers and the initiator, and perform a second heat treatment at the polymerization temperature;

[0096] Cool down, add a neutralizing agent, and perform a third insulation process within the neutralization temperature range;

[0097] Add deionized water to emulsify, and then perform a fourth heat treatment at around 50°C.

[0098] Filtration yields the aqueous secondary dispersion containing copolymer P.

[0099] For example, each heat preservation time is independently 0.5-2 hours.

[0100] Furthermore, the reaction temperature is determined by the selected initiation system. The preferred temperature after cooling is 80-120°C.

[0101] In this embodiment, the polymerization method of unsaturated monomers is well known to those skilled in the art. Typically, the reaction solvent is placed in a reaction vessel, and the monomer and initiator are added dropwise to carry out polymerization.

[0102] Preferably, the initiator is selected from at least one of azobisisobutyronitrile, benzoyl peroxide, dilauroyl peroxide, dicumyl peroxide, tert-butyl acetate peroxide, tert-amyl acetate peroxide, tert-butyl benzoate peroxide, tert-amyl benzoate peroxide, tert-butyl peroxide-2-ethylhexanoate, tert-amyl peroxide-2-ethylhexanoate, tert-butyl peroxide-2-ethylhexanoate, di-tert-butyl peroxide, and di-tert-amyl peroxide. The amount of initiator used is determined according to the desired molecular weight.

[0103] Preferably, the solvent is selected from at least one of butyl acetate, diethylene glycol dimethyl ether, solvent oil No. 100, solvent oil No. 200, toluene, xylene, ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, diacetone alcohol, ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, diethylene glycol methyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol ethyl ether, dipropylene glycol butyl ether, and dipropylene glycol dimethyl ether. The solvent or a mixture of solvents is selected based on the principle that the solvent boiling point is slightly higher than the reaction temperature. The solvent content is determined by the solids content at the end of copolymer P polymerization being between 50% and 90%, particularly preferably between 70% and 85%.

[0104] In this embodiment, the neutralizing agent is preferably an organic amine neutralizing agent. The organic amine is used to neutralize the carboxyl groups on the P-segment of the copolymer to provide the resin with sufficient water-based adaptability. Preferably, the organic amine is selected from at least one of ammonia, triethylamine, triethanolamine, dimethylethanolamine, 2-methyl-2-aminopropanol, dimethylisopropanolamine, methyldiethanolamine, ethyldiisopropylamine, and diethylethanolamine; the degree of neutralization is 50-110%, preferably 75-100%.

[0105] The final hydroxy acrylate aqueous dispersion was obtained by emulsification with deionized water to achieve the required solid content of the final dispersion.

[0106] Another embodiment of the present invention provides an aqueous coating comprising an aqueous secondary dispersion containing copolymer P as described above.

[0107] Specifically, the waterborne dispersion resin is mixed with a crosslinking agent to obtain the waterborne coating. Preferably, the crosslinking agent is selected from one or more of hydrophilic polyisocyanates and hydrophobic polyisocyanates.

[0108] The technical solution of the present invention will be described below with reference to some specific embodiments:

[0109] Preparation of monomer Y

[0110] The preparation method of monomer Y includes the following steps:

[0111] 200-300 parts of glycidyl tert-carbonate, 60-80 parts of acrylic acid, and 0-1 parts of p-hydroxyanisole are mixed and added to a reaction vessel and heated to 100-160℃. The acid value is then tested until it is less than 1 mg KOH / g, and the mixture is cooled to room temperature before being discharged. This yields monomer Y, whose structural formula is shown in Formula I below:

[0112]

[0113] In the following embodiments, unless otherwise specified, monomer Y is prepared by the above preparation method.

[0114] Example 1 (The hard monomer is styrene, with a content of 50 wt% in P2)

[0115] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, and dropwise add the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 120 parts of n-butyl methacrylate, and 80 parts of monomer Y) and 5 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour. Continue to dropwise add the second part of the monomer mixture (including 60 parts of hydroxyethyl methacrylate, 120 parts of styrene, and 20 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine, and keep at this temperature for 0.5 hours. Finally, dropwise add 1000 parts of deionized water, keep at this temperature for 1 hour, and filter to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0116] Example 2 (The hard monomer is cyclohexyl methacrylate, with a content of 50 wt% in P2)

[0117] Add 200 parts of dipropylene glycol methyl ether, heat to 150°C under nitrogen protection, and dropwise add the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 120 parts of butyl methacrylate, and 80 parts of monomer Y) and 5 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour. Continue to dropwise add the second part of the monomer mixture (including 60 parts of hydroxyethyl methacrylate, 120 parts of cyclohexyl methacrylate, and 20 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine, and keep at this temperature for 0.5 hours. Finally, dropwise add 1000 parts of deionized water, keep at this temperature for 1 hour, and filter to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0118] Example 3

[0119] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, and dropwise add the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 120 parts of butyl methacrylate, and 80 parts of monomer Y) and 5 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour. Continue to dropwise add the second part of the monomer mixture (including 60 parts of hydroxyethyl methacrylate, 120 parts of cyclohexyl methacrylate, and 20 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine, and keep at this temperature for 0.5 hours. Finally, dropwise add 1000 parts of deionized water, keep at this temperature for 1 hour, and filter to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0120] Example 4

[0121] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, add dropwise the first part of the monomer mixture (including 140 parts of n-butyl acrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 220 parts of butyl methacrylate, and 40 parts of monomer Y) and 5 parts of di-tert-amyl peroxide, keep warm for 1 hour, continue to add dropwise the second part of the monomer mixture (including 40 parts of hydroxyethyl methacrylate, 120 parts of styrene, 20 parts of acrylic acid, and 40 parts of monomer Y) and 2 parts of di-tert-amyl peroxide, keep warm for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine and keep warm for 0.5 hours, finally add 1000 parts of deionized water, keep warm for 1 hour, filter and discharge to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0122] Example 5

[0123] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, add dropwise the first part of the monomer mixture (including 140 parts of n-butyl acrylate, 220 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 40 parts of self-made monomer Y) and 5 parts of di-tert-amyl peroxide, keep warm for 1 hour, continue to add dropwise the second part of the monomer mixture (including 40 parts of hydroxyethyl methacrylate, 120 parts of isobornyl methacrylate, 20 parts of acrylic acid, 40 parts of self-made monomer Y) and 1.5 parts of di-tert-amyl peroxide, keep warm for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine and keep warm for 0.5 hours, finally add 1000 parts of deionized water, keep warm for 1 hour, filter and discharge to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0124] Example 6

[0125] Add 200 parts of dipropylene glycol methyl ether, heat to 150°C under nitrogen protection, and dropwise add the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 120 parts of butyl methacrylate, and 80 parts of self-made monomer Y) and 5 parts of di-tert-amyl peroxide. Keep warm for 1 hour, and continue to dropwise add the second part of the monomer mixture (including 60 parts of hydroxyethyl methacrylate, 120 parts of methyl methacrylate, and 20 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide. Keep warm for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine, and keep warm for 0.5 hours. Finally, dropwise add 1000 parts of deionized water, keep warm for 1 hour, filter and discharge to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0126] Example 7

[0127] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, add dropwise the first part of the monomer mixture (including 140 parts of n-butyl acrylate, 220 parts of methyl methacrylate, 140 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate) and 5 parts of di-tert-amyl peroxide, keep warm for 1 hour, continue to add dropwise the second part of the monomer mixture (including 40 parts of hydroxyethyl methacrylate, 120 parts of isobornyl methacrylate, 20 parts of acrylic acid, 40 parts of self-made monomer Y) and 1.5 parts of di-tert-amyl peroxide, keep warm for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine and keep warm for 0.5 hours, finally add 1000 parts of deionized water, keep warm for 1 hour, filter and discharge to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0128] Comparative Example 1

[0129] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, add dropwise the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 200 parts of butyl methacrylate) and 5 parts of di-tert-amyl peroxide, keep warm for 1 hour, continue to add dropwise the second part of the monomer mixture (including 60 parts of hydroxyethyl methacrylate, 70 parts of butyl methacrylate, 50 parts of butyl acrylate, 20 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide, keep warm for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine and keep warm for 0.5 hours, finally add 1000 parts of deionized water, keep warm for 1 hour, filter and discharge to obtain an aqueous secondary dispersion of hydroxyacrylate.

[0130] Comparative Example 2

[0131] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, add dropwise the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 200 parts of butyl methacrylate) and 5 parts of di-tert-amyl peroxide, keep warm for 1 hour, continue to add dropwise the second part of the monomer mixture (including 60 parts of hydroxyethyl methacrylate, 50 parts of styrene, 70 parts of butyl acrylate, 20 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide, keep warm for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine and keep warm for 0.5 hours, finally add 1000 parts of deionized water, keep warm for 1 hour, filter and discharge to obtain an aqueous secondary dispersion of hydroxyacrylate.

[0132] Comparative Example 3

[0133] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, add dropwise the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 200 parts of isobornyl methacrylate) and 5 parts of di-tert-amyl peroxide, keep warm for 1 hour, continue to add dropwise the second part of the monomer mixture (including 60 parts of hydroxyethyl methacrylate, 50 parts of styrene, 70 parts of butyl acrylate, 20 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide, keep warm for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine and keep warm for 0.5 hours, finally add 1000 parts of deionized water, keep warm for 1 hour, filter and discharge to obtain an aqueous secondary dispersion of hydroxyacrylate.

[0134] Comparative Example 4

[0135] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, and dropwise add the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 120 parts of n-butyl methacrylate, and 80 parts of monomer Y) and 5 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour. Continue to dropwise add the second part of the monomer mixture (including 60 parts of hydroxyethyl methacrylate, 70 parts of styrene, 50 parts of n-butyl acrylate, and 20 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine, and keep at this temperature for 0.5 hours. Finally, dropwise add 1000 parts of deionized water, keep at this temperature for 1 hour, and filter to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0136] Comparative Example 5

[0137] Add 200 parts of propylene glycol butyl ether, heat to 150°C under nitrogen protection, and dropwise add the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 120 parts of n-butyl methacrylate, and 80 parts of monomer Y) and 5 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour. Continue to dropwise add the second part of the monomer mixture (including 50 parts of hydroxyethyl methacrylate, 145 parts of styrene, and 5 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide. Keep at this temperature for 1 hour. Then cool to a certain temperature, add 25 parts of triethylamine, and keep at this temperature for 0.5 hours. Finally, dropwise add 1000 parts of deionized water, keep at this temperature for 1 hour, and filter to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0138] Comparative Example 6

[0139] Add 200 parts of dipropylene glycol methyl ether, heat to 150°C under nitrogen protection, and dropwise add the first part of the monomer mixture (including 100 parts of n-butyl acrylate, 100 parts of methyl methacrylate, 100 parts of isooctyl acrylate, 140 parts of styrene, 160 parts of hydroxyethyl methacrylate, 120 parts of butyl methacrylate, and 80 parts of monomer Y) and 5 parts of di-tert-amyl peroxide. Keep warm for 1 hour, and continue to dropwise add the second part of the monomer mixture (including 60 parts of hydroxyethyl methacrylate, 120 parts of lauryl acrylate, and 20 parts of acrylic acid) and 2 parts of di-tert-amyl peroxide. Keep warm for 1 hour, then cool to a certain temperature, add 25 parts of triethylamine, and keep warm for 0.5 hours. Finally, dropwise add 1000 parts of deionized water, keep warm for 1 hour, filter and discharge to obtain the aqueous secondary dispersion of hydroxyacrylate with excellent bubble-free film thickness.

[0140] The performance test results of each embodiment and comparative example are shown in Table 1 below:

[0141] Table 1

[0142]

[0143]

[0144] Note:

[0145] The bubble-free film thickness was tested at 35°C and 40% RH. It was used with Covestro 3900 curing agent and an automated spraying equipment to spray gradient film thickness on tinplate. The baking conditions were 60°C for 1 hour. After that, the bubbling limit was observed and tested.

[0146] Looking at the monomer composition and formulation of Comparative Example 1, its hydrophobic polymer does not contain hard monomers, resulting in a lower bubble-free film thickness, which affects its applicability. While Comparative Example 2 introduced some hard monomers (styrene) into the hydrophobic polymer segment, the content was low, and although it improved the bubble-free film thickness, the improvement was not significant. Comparative Example 6 improved the bubble-free film thickness by introducing long-chain acrylate structures into the resin structure; however, the introduction of this monomer significantly weakened the glass transition temperature, resulting in a softer film and affecting the final performance.

[0147] The hydroxy acrylate aqueous dispersion prepared by this invention has a simple and operable synthesis process, and the resin has a bubble-free film thickness and hardness that meet the application requirements. It can be used as the hydroxy resin component of two-component polyurethane coatings, and can be used with water-based and oil-based diisocyanate components to formulate high-performance water-based polyurethane coatings.

[0148] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An aqueous secondary dispersion containing copolymer P, characterized in that, The copolymer P is synthesized from the following components: 1) Hydrophobic polymers containing the following components as structural unit monomers: A1 contains 10-30 wt% hydroxyl monomers, selected from at least one of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate. B1 70-90 wt% of acrylate monomers and / or vinyl monomers, selected from at least one of methyl methacrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, coconut oleate methacrylate, octadecyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, glycidyl methacrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and... 2) Hydrophilic polymers containing the following components as structural unit monomers: A2 contains 15-35 wt% hydroxyl monomers selected from at least one of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate. B2 homopolymer has 40-70 wt% acrylate monomers and / or vinyl monomers with a Tg greater than 80℃, selected from one or more of methyl methacrylate, styrene, cyclohexyl methacrylate, and isobornyl methacrylate. C. The Tg of the homopolymer is 0-10 wt% of the acrylate monomer below 80℃. D contains 10-15 wt% carboxyl monomers, selected from at least one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid; The structural unit monomers of hydroxyl-containing hydrophobic polymers and / or hydroxyl-containing hydrophilic polymers also contain monomer Y; In this copolymer, monomer Y is an acrylate monomer prepared by ring-opening of a carboxyl-containing monomer and glycidyl tert-carbonate, and the content of monomer Y accounts for 2-10 wt% of the total content of all components in copolymer P. The carboxyl-containing monomer is acrylic acid; The hydroxyl-containing hydrophilic polymer acts as an emulsifier, encapsulating the hydroxyl-containing hydrophobic polymer and dispersing it in water.

2. The aqueous secondary dispersion containing copolymer P according to claim 1, characterized in that, The copolymer P contains the following amounts of hydroxyl-containing hydrophobic polymer and hydroxyl-containing hydrophilic polymer: Hydrophobic polymers containing hydroxyl groups 50-90 wt% Hydrophilic polymers containing hydroxyl groups, 10-50 wt%.

3. The aqueous secondary dispersion containing copolymer P according to claim 1, characterized in that, The solid content of the aqueous secondary dispersion is 30%-70%.

4. The aqueous secondary dispersion containing copolymer P according to claim 1, characterized in that, The solid content of the aqueous secondary dispersion is 40%-60%.

5. The aqueous secondary dispersion containing copolymer P according to claim 1, characterized in that, The copolymer P has a molecular weight of 4000-10000 g / mol.

6. The aqueous secondary dispersion containing copolymer P according to claim 1, characterized in that, The copolymer P has a molecular weight of 5000-8000 g / mol.

7. The aqueous secondary dispersion containing copolymer P according to claim 1, characterized in that, The C acrylate monomer is selected from at least one of methyl acrylate, sec-butyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, coconut oleate methacrylate, octadecyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, glycidyl methacrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate.

8. The method for preparing an aqueous secondary dispersion containing copolymer P according to any one of claims 1-7, characterized in that, Includes the following steps: Under a nitrogen atmosphere, monomers and initiators that form hydroxyl-containing hydrophobic polymers are added to the solvent at the reaction temperature, followed by a first heating. Add structural unit monomers and initiators to form hydroxyl-containing hydrophilic polymers, and perform a second heat preservation; Cool down, add a neutralizing agent, and perform a third insulation process; Add deionized water for emulsification, and then perform a fourth heat treatment. Filtration yields the aqueous secondary dispersion containing copolymer P.

9. An aqueous coating comprising an aqueous secondary dispersion containing copolymer P as described in any one of claims 1-7.

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