A dual-crosslinked acrylic secondary dispersion, its preparation method and application

Abstract

The present invention discloses a double-crosslinked acrylic secondary dispersion, its preparation method and application, relating to the field of coatings. The double-crosslinked acrylic secondary dispersion comprises a copolymer and water. The copolymer comprises a secondary amine group prepolymer, a solvent, a first mixed monomer, a second mixed monomer, an initiator, and a neutralizing agent. The secondary amine group prepolymer is prepolymerized from a polyprimary amine and a polyfunctional acrylate monomer, and its primary amine value is less than 4 mg KOH / g. The double-crosslinked acrylic secondary dispersion provided by the present invention crosslinks through the simultaneous reaction of secondary amine and hydroxyl with isocyanate, so that the coating film not only has the characteristics of high gloss, good fullness, good leveling property, and good flexibility, but also shows a short dry-to-touch time, fast hardness establishment, high crosslinking density, good adhesion to various substrates, and excellent water resistance, chemical resistance and weather resistance compared with conventional waterborne two-component polyurethane coatings.

Description

Technical Field

[0001] The invention relates to the field of coatings, and in particular to a double-crosslinked acrylic acid secondary dispersion and a preparation method and application thereof. Background Art

[0002] As people's environmental awareness increases and environmental regulations become increasingly stringent, water-based paints are gradually replacing solvent-based paints because of their safety and environmental protection, and are one of the main development directions of the current paint industry. Water-based hydroxy acrylic resins, as film-forming substances for water-based paints, are cross-linked and cured with polyisocyanate curing agents, making the coatings have high gloss, high hardness, excellent weather resistance and chemical resistance, and therefore have received extensive attention and research.

[0003] However, conventional water-based two-component polyurethane coatings prepared from water-based hydroxyl acrylic resins react the hydroxyl groups in component A (made from hydroxyl acrylic resin) with the isocyanate groups in component B (polyisocyanate curing agent) to form a paint film with a network cross-linked structure. However, since water is used as the dispersion medium, polyisocyanates will inevitably react with water. Under normal circumstances, when a polyisocyanate curing agent is added, it is often necessary to add an extra portion of polyisocyanate curing agent, which not only makes the chemical cross-linking insufficient to a certain extent, but also virtually increases the cost of water-based coatings. Summary of the invention

[0004] The present invention provides a double-crosslinked acrylic secondary dispersion and a preparation method and application thereof. The acrylic secondary dispersion simultaneously introduces secondary amine groups and hydroxyl groups and has a "core-shell structure" and can be used to undergo double crosslinking with a polyisocyanate curing agent in sequence to improve the curing performance of a coating. The coating has the advantages of short actual drying time, fast hardness build-up, high crosslinking density, good adhesion to various substrates, good activation period, and excellent water resistance, chemical resistance, and weather resistance.

[0005] In order to solve the above technical problems, one of the purposes of the present invention is to provide a double cross-linked acrylic secondary dispersion, comprising a copolymer and water, wherein the solid content of the double cross-linked acrylic dispersion is greater than 38wt%, and the copolymer comprises the following components in parts by weight: 240 parts to 900 parts of a secondary amine group prepolymer, 250 parts to 500 parts of a solvent, 1000 parts to 1800 parts of a first mixed monomer, 300 parts to 720 parts of a second mixed monomer, 60 parts to 120 parts of an initiator, and 90 parts to 120 parts of a neutralizer;

[0006] The secondary amine group prepolymer is formed by prepolymerizing 13wt%-49wt% of a polyvalent primary amine and 51wt%-87wt% of a multifunctional acrylate monomer, and the primary amine value of the secondary amine group prepolymer is less than 4mgKOH / g;

[0007] The first mixed monomer comprises the following components: 62 wt% - 95 wt% (meth)acrylate monomer and 5 wt% - 38 wt% hydroxyl functional monomer;

[0008] The second mixed monomer comprises the following components: 26 wt% - 56 wt% hydroxyl functional monomer, 10 wt% - 25 wt% carboxyl functional monomer, and the balance (meth)acrylate monomer.

[0009] In this application, a secondary amine group prepolymer containing a secondary amine group and an unsaturated double bond is added to a solvent, and under the action of an initiator, it polymerizes with the first mixed monomer to form a hydrophobic copolymer A, and then the second mixed monomer polymerizes to form a hydrophilic copolymer B, thereby obtaining a copolymer mixture; a double-crosslinked acrylic secondary dispersion containing the copolymer mixture is obtained, and the double-crosslinked acrylic dispersion has both a secondary amine group and a hydroxyl group as two reactive groups; since the reaction rate of a primary amine with an isocyanate is much faster than that of a secondary amine, the prepolymer converts the primary amine into a secondary amine, reducing the primary amine value to less than 4 mg KOH / g to ensure sufficient operating time when an isocyanate curing agent is added to the later paint and extending the activation period.

[0010] As a preferred embodiment, the solid content of the double-crosslinked acrylic dispersion is 38 wt% - 60 wt%.

[0011] As a preferred embodiment, the weight ratio of the copolymer to water is 1:(0.6 - 0.9).

[0012] As a preferred embodiment, the hydroxyl value of the double-crosslinked acrylic dispersion based on 100% solid content is 45 - 160 mg KOH / g, the acid value is 20 - 32 mg KOH / g, and the amine value is 16 - 66 mg KOH / g.

[0013] As a preferred embodiment, the (meth)acrylate monomer includes at least one of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and α-methylstyrene.

[0014] As a preferred embodiment, the hydroxyl functional monomer includes at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate.

[0015] As a preferred embodiment, the carboxyl functional monomer includes at least one of acrylic acid, methacrylic acid, itaconic acid, β-carboxyethyl acrylate, crotonic acid, fumaric acid, maleic acid, and maleic anhydride.

[0016] As a preferred embodiment, the polyfunctional acrylate monomer is a difunctional acrylate monomer and / or a trifunctional acrylate monomer.

[0017] As a preferred embodiment, the polyvalent primary amine is a monovalent primary amine, a divalent primary amine or a polyetheramine.

[0018] As a preferred embodiment, the initiator includes at least one of tert-butyl 2-ethylhexylperoxide, tert-amyl 2-ethylhexylperoxide, tert-butyl benzoate peroxide and tert-amyl benzoate peroxide.

[0019] As a preferred embodiment, the molar ratio of the neutralizing agent to the carboxyl functional monomer is (1.1 - 1.2):1, and the neutralizing agent is an organic amine and / or a water-soluble inorganic base.

[0020] As a preferred embodiment, the organic amine includes at least one of dimethylethanolamine, methylethanolamine, triethylamine and triethanolamine.

[0021] As a preferred embodiment, the solvent includes 30 wt% - 95 wt% of a hydrophobic solvent and 5 wt - 95 wt% of a water-soluble solvent.

[0022] As a preferred embodiment, the hydrophobic solvent includes one of xylene, toluene, naphtha, aliphatic ester, aliphatic hydrocarbon and aromatic hydrocarbon.

[0023] As a preferred embodiment, the water-soluble solvent includes an alcohol ether solvent.

[0024] As a preferred embodiment, the water-soluble solvent includes at least one of ethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol monobutyl ether and dipropylene glycol monobutyl ether.

[0025] As a preferred embodiment, the preparation method of the secondary amine group prepolymer is: heating the polyvalent primary amine to 20°C - 80°C, stirring and slowly dropping the polyfunctional acrylate monomer, and after the dropping is completed, keeping the temperature for 24 - 48 h. When the primary amine value is less than 4 mg KOH / g, the reaction is completed.

[0026] As a preferred embodiment, the molar ratio of the polyfunctional acrylate monomer to the polyvalent primary amine is 1.0 - 2.5.

[0027] Since the reaction rate between the primary amine group and the polyisocyanate group is too fast, which will affect the pot life (activation period) of the coating. In order to make the primary amine in the polyvalent primary amine tend to be completely converted into secondary amine groups during the preparation of the secondary amine group prepolymer, the molar number of the polyfunctional acrylate monomer should exceed the theoretical molar number by 2 - 3% (the unsaturated double bond is in excess).

[0028] As a preferred embodiment, the polyfunctional acrylic monomer includes C1 - C 18 of (meth)acrylate.

[0029] Preferably, the polyfunctional acrylic monomer includes at least one of 1,6 - hexanediol diacrylate, ethoxylated 1,6 - hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, 3 - ethoxy - trimethylolpropane triacrylate, propoxytrimethylolpropane triacrylate, and pentaerythritol triacrylate.

[0030] Preferably, the primary monoamine includes at least one of ethanolamine, methylamine, ethylamine, n - propylamine, isopropylamine, n - butylamine, isobutylamine, sec - butylamine, tert - butylamine, n - pentylamine, n - hexylamine, n - octylamine, 2 - ethylhexylamine, dodecylamine, tetradecylamine, octadecylamine, eicosylamine, 2 - methoxyethylamine, 2 - ethoxyethylamine, 3 - methoxypropylamine, 3 - ethoxypropylamine, 2 - methylthioethylamine, cyclopropylamine, cyclopentylamine, cyclohexylamine, cyclohexylmethylamine, allylamine, propargylamine, benzylamine, phenethylamine, 3 - phenyl - 1 - propylamine, 4 - phenyl - 1 - butylamine, 2 - aminomethylpyridine, aminopyridine, aniline, and naphthylamine.

[0031] Preferably, the secondary diamine is an aliphatic acyclic diamine, an aliphatic cyclic diamine, or an araliphatic diamine. Compared with aromatic primary amines, aliphatic acyclic diamines and aliphatic cyclic diamines are less likely to cause yellowing of the paint film and affect weather resistance.

[0032] The double - crosslinked acrylic secondary dispersion prepared based on cycloaliphatic diamine in this application has a slower reaction rate with isocyanate than the double - crosslinked acrylic secondary dispersion prepared based on polyetheramine and acyclic secondary diamine, resulting in greater flexibility in the pot life (activation period). This is because the cyclic structure has a certain steric hindrance effect, making the secondary amino group less active, thus extending the pot life (activation period), and the cyclic structure brings more excellent water resistance and chemical resistance.

[0033] For the double - crosslinked acrylic secondary dispersion prepared based on polyetheramine in this application, the polyetheramine itself provides certain hydrophilic groups, which is helpful for reducing the acid value of the copolymer, thereby improving water resistance. Moreover, the double - crosslinked acrylic secondary dispersion prepared based on polyetheramine also has a certain improvement in the flexibility of the paint film.

[0034] Preferably, the aliphatic acyclic diamine includes ethylenediamine, 1,2 - diaminopropane, 1,4 - diaminobutane, 1,5 - diaminopentane, 1,6 - diaminohexane, 1,5 - diamino - 2 - methylpentane, 2,5 - diamino - 2,5 - dimethylhexane, 2,2,4 - trimethyl - 1,6 - diaminohexane, 2,4,4 - trimethyl - 1,6 - diaminohexane, 1,1 - diaminoundecane, and 1,12 - diaminododecane.

[0035] Preferably, the aliphatic cyclic diamine includes 1-amino-3,3,5-trimethyl-5-aminomethyl cyclohexane, 2,4-hexahydrotoluenediamine, 2,6-hexahydrotoluenediamine, 2,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylmethane, isopropyl-2,4-diaminocyclohexane, isopropyl-2,6-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 2,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, diaminodicyclohexylmethane, 3(4)-aminomethyl-1-methylcyclohexylamine.

[0036] Preferably, the araliphatic diamine includes at least one of 1,3-bis(aminomethyl)benzene, m-xylylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4'-diaminodiphenyl-methane, 4,4'-diaminodiphenyl-methane.

[0037] Preferably, the polyetheramine includes at least one of M-600, M-1000, M-2070, M-3080, D-230, D-400 from Huntsman Jeffamine series.

[0038] To solve the above technical problems, the second object of the present invention provides a method for preparing a double-crosslinked acrylic secondary dispersion, comprising the following steps:

[0039] (1) After mixing the secondary amine group prepolymer and the solvent, the first mixed monomer, the second mixed monomer are successively added dropwise, and the initiator is added dropwise synchronously with the first mixed monomer and the second mixed monomer. The temperature during the dropping process is maintained at 120°C - 130°C. After the dropping is completed, keep stirring for 2h - 4h, cool to 95 - 105°C, add the neutralizing agent, and keep stirring for 20min - 40min to obtain a copolymer;

[0040] (2) Mix and disperse the copolymer and water evenly to obtain a double-crosslinked acrylic secondary dispersion.

[0041] To solve the above technical problems, the third object of the present invention provides an application of the double-crosslinked acrylic secondary dispersion in the field of preparing waterborne coatings.

[0042] To solve the above technical problems, the fourth object of the present invention is to provide an aqueous two-component polyurethane coating, which includes component A and component B. By total mass percentage, component A includes 50wt%-70wt% of a double-crosslinked acrylic secondary dispersion, 10wt%-15wt% of water, 3wt%-8wt% of a co-solvent, and the balance of additives. The additives include at least one of a pH regulator, a wetting agent, a dispersant, a leveling agent, an antifoaming agent, a thickener, a catalyst, an anti-settling agent, and a pigment and filler; component B includes 14wt%-17wt% of an isocyanate curing agent and 3wt%-6wt% of a co-solvent.

[0043] As a preferred embodiment, the isocyanate curing agent includes a hydrophilic polyisocyanate and / or a hydrophobic polyisocyanate.

[0044] As a preferred embodiment, the hydrophilic polyisocyanate is obtained by modifying a polyisocyanate with one of a carboxylate, a sulfonate, and a polyethylene oxide group.

[0045] As a preferred embodiment, the isocyanate curing agent includes at least one of isophorone diisocyanate, hexamethylene diisocyanate, and 1,6-hexanediisocyanate.

[0046] As a preferred embodiment, the isocyanate curing agent is Bayhydur XP2655.

[0047] As a preferred embodiment, the co-solvent is at least one of ethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, propylene glycol methyl ether acetate, and N,N-dimethylethanolamine.

[0048] As a preferred embodiment, the pigment and filler includes an inorganic pigment and / or an organic pigment.

[0049] As a preferred embodiment, the inorganic pigment includes at least one of titanium dioxide, iron oxide, carbon black, pearlescent pigment, and metallic pigment, and the metallic pigment includes at least one of aluminum powder and silver powder.

[0050] As a preferred embodiment, the thickener is a non-ionic polyurethane thickener, which has better transparency and better emulsification during construction; the wetting agent is a wetting agent of an alkyl-modified polyether, which can effectively improve the transparency, gloss, and smoothness of the paint coating.

[0051] As a preferred embodiment, the pH regulator is an organic amine, and the organic amine includes at least one of triethylamine and dimethylethanolamine.

[0052] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0053] (1) The dual-crosslinked acrylic secondary dispersion provided by the present invention utilizes a polyprimary amine and a multifunctional acrylate monomer to carry out a "Michael addition reaction" to form a prepolymer containing a secondary amine reactive group and an unsaturated double bond, and then further undergoes a free radical polymerization with other acrylic monomers to obtain an acrylic secondary dispersion having both a secondary amine group and a hydroxyl group;

[0054] (1) The dual-crosslinked acrylic secondary dispersion provided by the present invention has a "core-shell structure", and the secondary amine group prepolymer and the first mixed monomer are used as the core layer and are wrapped inside. After the surface drying of the coating occurs, the secondary amine groups in the core layer react with the polyisocyanate, and the reaction rate is faster than that of the hydroxyl group and water, thereby increasing the crosslinking density and the dry-to-touch time. At the same time, the generated urea bonds have better adhesion to various substrates;

[0055] (2) The dual-crosslinked acrylic secondary dispersion provided by the present invention crosslinks through the simultaneous reaction of the secondary amine and the hydroxyl group with isocyanate, so that the coating not only has the characteristics of high gloss, good fullness, good leveling property, and good flexibility, but also shows a short dry-to-touch time, fast hardness establishment, large crosslinking density, good adhesion to various substrates, and excellent water resistance, chemical resistance, and weather resistance compared with conventional waterborne two-component polyurethane coatings. Specific Embodiments

[0056] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0057] Preparation Example 1

[0058] A dual-crosslinked acrylic secondary dispersion with a solid content of about 45% (the solid content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxydicarbonate), including a copolymer mixture and 2600 g of water. The copolymer mixture includes 380 g of the secondary amine group prepolymer, 280 g of ethyl 3-ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 520 g of methyl methacrylate, 319 g of n-butyl acrylate, 220 g of n-butyl methacrylate, and 350 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 157 g of methyl methacrylate, 150 g of n-butyl acrylate, 250 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid; the initiator includes 64 g of tert-butyl 2-ethylhexyl peroxydicarbonate and 32 g of propylene glycol methyl ether; its preparation method includes the following steps:

[0059] (1) Add 340 g of 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane (IPDA) to a 1-L reaction vessel. Heat the temperature to 50 °C and slowly add dropwise 465 g of 1,6-hexanediol diacrylate. After the addition is complete, keep the temperature for 24 - 48 hours. Detect the primary amine value in the reaction system. When the primary amine value is less than 4 mg KOH / g, it is determined that the reaction is complete, obtaining a secondary amine group prepolymer with an amine value of 139.4 mg KOH / g and a hydroxyl value of 0 mg KOH / g;

[0060] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether to a 5-L reaction vessel. Maintain the temperature in the reaction vessel at 125 °C. Premix the first mixed monomer and then add it dropwise into the reaction vessel at a constant speed while adding a initiator dropwise at the same time. The addition is completed in 3 hours. The first mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 106.4 mg KOH / g and an acid value of 0 mg KOH / g;

[0061] (3) Maintain the temperature in the reaction vessel at 125 °C. Premix the second mixed monomer and then add it dropwise into the reaction vessel at a constant speed while adding a initiator dropwise at the same time. The addition is completed in 1.5 hours. The initiator is added dropwise within 5 hours. The second mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 165.5 mg KOH / g and an acid value of 108.4 mg KOH / g;

[0062] (4) Continue to stir at 125 °C for 2 hours, then cool to 100 °C. Add 111 g of dimethylethanolamine to the reaction vessel and continue to stir at 100 °C for 30 minutes to obtain a copolymer mixture;

[0063] (5) Add the copolymer mixture to deionized water and stir for dispersion for 30 minutes to obtain a double cross-linked acrylic secondary dispersion.

[0064] Preparation Example II

[0065] A double-crosslinked acrylic secondary dispersion with a solids content of approximately 45% (the solids content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxydicarbonate), including a copolymer mixture and 2600 g of water. The copolymer mixture includes 500 g of the secondary amine group prepolymer, 280 g of ethyl 3-ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 500 g of methyl methacrylate, 301 g of n-butyl acrylate, 200 g of n-butyl methacrylate, and 350 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 150 g of methyl methacrylate, 100 g of n-butyl acrylate, 250 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid. The initiator includes 59 g of tert-butyl 2-ethylhexyl peroxydicarbonate and 29 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0066] (1) Add 238 g of 3,3'-dimethyl-4,4-diaminodicyclohexylmethane to a 1 L reaction vessel, heat up to 50 °C, and slowly dropwise add 465 g of 1,6-hexanediol diacrylate. After the addition is completed, keep the temperature for 24 - 48 hours, and detect the primary amine value in the reaction system. When the primary amine value is less than 4 mg KOH / g, it is determined that the reaction is completed to obtain the secondary amine group prepolymer with an amine value of 159.6 mg KOH / g and a hydroxyl value of 0 mg KOH / g;

[0067] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether to a 5 L reaction vessel, maintain the temperature in the reaction vessel at 125 °C, pre-mix the first mixed monomer and then drop it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator. The addition is completed in 3 h. The first mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 111 mg KOH / g and an acid value of 0 mg KOH / g;

[0068] (3) Maintain the temperature in the reaction vessel at 125 °C, pre-mix the second mixed monomer and then drop it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator. The addition is completed in 1.5 h, and the initiator is added dropwise within 5 h. The second mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 181.5 mg KOH / g and an acid value of 118.9 mg KOH / g;

[0069] (4) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine to the reaction vessel, and continue to stir at 100 °C for 30 min to obtain the copolymer mixture;

[0070] (5) Add the copolymer mixture to deionized water and stir for 30 min to obtain the double-crosslinked acrylic secondary dispersion.

[0071] Preparation Example Three

[0072] A double-crosslinked acrylic secondary dispersion with a solids content of about 45% (the solids content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxyacid), including a copolymer mixture and 2600 g of water. The copolymer mixture includes 630 g of the secondary amine group prepolymer, 280 g of ethyl 3-ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 421 g of methyl methacrylate, 373 g of n-butyl acrylate, 150 g of n-butyl methacrylate, and 350 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 70 g of methyl methacrylate, 110 g of n-butyl acrylate, 250 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid. The initiator includes 56 g of tert-butyl 2-ethylhexyl peroxyacid and 28 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0073] (1) Add 210 g of 4,4'-diaminodicyclohexylmethane to a 1 L reaction vessel, heat up to 50 °C, and slowly dropwise add 495 g of dipropylene glycol diacrylate. After the addition is completed, keep the temperature for 24 - 48 hours, and detect the primary amine value in the reaction system. When the primary amine value is less than 4 mg KOH / g, it is determined that the reaction is completed to obtain the secondary amine group prepolymer with an amine value of 159 mg KOH / g and a hydroxyl value of 0 mg KOH / g;

[0074] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether into a 5 L reaction vessel, keep the temperature in the reaction vessel at 125 °C, premix the first mixed monomer and then drop it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator. The addition is completed in 3 h. The first mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 115.8 mg KOH / g and an acid value of 0 mg KOH / g;

[0075] (3) Keep the temperature in the reaction vessel at 125 °C, premix the second mixed monomer and then drop it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator. The addition is completed in 1.5 h, and the initiator is added dropwise within 5 h. The second mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 206 mg KOH / g and an acid value of 134.5 mg KOH / g;

[0076] (4) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine to the reaction vessel, and continue to stir at 100 °C for 30 min to obtain the copolymer mixture;

[0077] (5) Add the copolymer mixture to deionized water and stir and disperse for 30 min to obtain the double-crosslinked acrylic secondary dispersion.

[0078] Preparation Example 4

[0079] A double-crosslinked acrylic secondary dispersion with a solids content of approximately 45% (the solids content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxyacid), including a copolymer mixture and 2600 g of water. The copolymer mixture includes 760 g of the secondary amine group prepolymer, 280 g of ethyl ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 473 g of methyl methacrylate, 278 g of n-butyl acrylate, 120 g of n-butyl methacrylate, and 350 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 47 g of methyl methacrylate, 80 g of n-butyl acrylate, 250 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid. The initiator includes 52 g of tert-butyl 2-ethylhexyl peroxyacid and 26 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0080] (1) Add 198 g of cyclohexylamine to a 1 L reaction vessel, heat up to 50 °C, and slowly dropwise add 610 g of pentaerythritol triacrylate. After the addition is complete, keep the temperature for 24 - 48 hours, and detect the primary amine value in the reaction system. When the primary amine value is less than 4 mg KOH / g, it is determined that the reaction is complete to obtain the secondary amine group prepolymer with an amine value of 138.9 mg KOH / g and a hydroxyl value of 0 mg KOH / g;

[0081] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether into a 5 L reaction vessel, maintain the temperature in the reaction vessel at 125 °C, premix the first mixed monomer and then drop it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator. The addition is completed in 3 h. The first mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 122.8 mg KOH / g and an acid value of 0 mg KOH / g;

[0082] (3) Maintain the temperature in the reaction vessel at 125 °C, premix the second mixed monomer and then drop it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator. The addition is completed in 1.5 h, and the initiator is added dropwise within 5 h. The second mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 229.3 mg KOH / g and an acid value of 150.2 mg KOH / g;

[0083] (4) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine to the reaction vessel, and continue to stir at 100 °C for 30 min to obtain the copolymer mixture;

[0084] (5) Add the copolymer mixture to deionized water and stir and disperse for 30 min to obtain the double-crosslinked acrylic secondary dispersion.

[0085] Preparation Example V

[0086] A double-crosslinked acrylic secondary dispersion with a solids content of about 45% (the solids content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexylperoxide), including a copolymer mixture and 2600 g of water. The copolymer mixture includes 760 g of the secondary amine group prepolymer, 280 g of ethyl ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 461 g of methyl methacrylate, 390 g of n-butyl acrylate, 120 g of n-butyl methacrylate, and 250 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 47 g of methyl methacrylate, 80 g of n-butyl acrylate, 250 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid. The initiator includes 52 g of tert-butyl 2-ethylhexylperoxide and 26 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0087] (1) Add 152.5 g of ethanolamine to a 1 L reaction vessel, heat up to 50 °C, and slowly dropwise add 760 g of trimethylolpropane triacrylate. After the addition is complete, keep warm for 24 - 48 hours, and detect the primary amine value in the reaction system. When the primary amine value is less than 4 mg KOH / g, it is determined that the reaction is complete, obtaining the secondary amine group prepolymer with an amine value of 153.7 mg KOH / g and a hydroxyl value of 61.5 mg KOH / g;

[0088] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether into a 5 L reaction vessel. Keep the temperature in the reaction vessel at 125 °C. Premix the first mixed monomer and then drop it into the reaction vessel at a constant speed, while dropping the initiator at the same time. The dropping is completed in 3 h. The first mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 87.7 mg KOH / g and an acid value of 0 mg KOH / g;

[0089] (3) Keep the temperature in the reaction vessel at 125 °C. Premix the second mixed monomer and then drop it into the reaction vessel at a constant speed, while dropping the initiator at the same time. The dropping is completed in 1.5 h, and the initiator is dropped in within 5 h. The second mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 229.3 mg KOH / g and an acid value of 150.2 mg KOH / g;

[0090] (4) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine to the reaction vessel, and continue to stir at 100 °C for 30 min to obtain the copolymer mixture;

[0091] (5) Add the copolymer mixture to deionized water and stir for dispersion for 30 min to obtain the double-crosslinked acrylic secondary dispersion.

[0092] Preparation Example VI

[0093] A double-crosslinked acrylic secondary dispersion with a solids content of approximately 45% (the solids content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxydicarbonate), including a copolymer mixture and 2600 g of water. The copolymer mixture includes 760 g of the secondary amine group prepolymer, 280 g of ethyl ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 473 g of methyl methacrylate, 278 g of n-butyl acrylate, 120 g of n-butyl methacrylate, and 350 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 57 g of methyl methacrylate, 80 g of n-butyl acrylate, 250 g of 2-hydroxyethyl methacrylate, and 80 g of acrylic acid. The initiator includes 52 g of tert-butyl 2-ethylhexyl peroxydicarbonate and 26 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0094] (1) Add 230 g of D-230 polyetheramine from Huntsman Corporation to a 1 L reaction vessel, heat up to 50 °C, and slowly dropwise add 465 g of 1,6-hexanediol diacrylate. After the addition is complete, keep the temperature for 24 - 48 hours, and detect the primary amine value in the reaction system. When the primary amine value is less than 4 mg KOH / g, it is determined that the reaction is complete, obtaining the secondary amine group prepolymer with an amine value of 162 mg KOH / g and a hydroxyl value of 0 mg KOH / g;

[0095] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether into a 5 L reaction vessel. Keep the temperature in the reaction vessel at 125 °C. Premix the first mixed monomer and then dropwise add it into the reaction vessel at a constant speed while dropping the initiator. The addition is completed in 3 h. The first mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 122.8 mg KOH / g and an acid value of 0 mg KOH / g;

[0096] (3) Keep the temperature in the reaction vessel at 125 °C. Premix the second mixed monomer and then dropwise add it into the reaction vessel at a constant speed while dropping the initiator. The addition is completed in 1.5 h. The initiator is added dropwise within 5 h. The second mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 229.3 mg KOH / g and an acid value of 133.5 mg KOH / g;

[0097] (4) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine into the reaction vessel, and continue to stir at 100 °C for 30 min to obtain the copolymer mixture;

[0098] (5) Add the copolymer mixture into deionized water and stir for dispersion for 30 min to obtain the double-crosslinked acrylic secondary dispersion.

[0099] Preparation Example VII

[0100] A double-crosslinked acrylic secondary dispersion with a solids content of approximately 45% (the solids content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxyacid), including a copolymer mixture and 2600 g of water. The copolymer mixture includes 380 g of the secondary amine group prepolymer, 280 g of ethyl ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 508 g of methyl methacrylate, 385 g of n-butyl acrylate, 200 g of n-butyl methacrylate, and 580 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 35 g of methyl methacrylate, 60 g of n-butyl acrylate, 200 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid. The initiator includes 62 g of tert-butyl 2-ethylhexyl peroxyacid and 31 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0101] (1) Add 119 g of 3,3'-dimethyl-4,4-diaminodicyclohexylmethane and 99 g of cyclohexylamine to a 1 L reaction vessel, heat up to 50 °C, and slowly dropwise add 465 g of 1,6-hexanediol diacrylate. After the addition is complete, keep warm for 24 - 48 hours, and detect the primary amine value in the reaction system. When the primary amine value is less than 4 mg KOH / g, it is determined that the reaction is complete to obtain the secondary amine group prepolymer with an amine value of 164.28 mg KOH / g and a hydroxyl value of 0 mg KOH / g;

[0102] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether to a 5 L reaction vessel, maintain the temperature in the reaction vessel at 125 °C, premix the first mixed monomer and then dropwise add it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator. The addition is completed in 3 h. The first mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 148.4 mg KOH / g and an acid value of 0 mg KOH / g;

[0103] (3) Maintain the temperature in the reaction vessel at 125 °C, premix the second mixed monomer and then dropwise add it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator. The addition is completed in 1.5 h, and the initiator is added dropwise within 5 h. The second mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 222.5 mg KOH / g and an acid value of 182.2 mg KOH / g;

[0104] (4) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine to the reaction vessel, and continue to stir at 100 °C for 30 min to obtain the copolymer mixture;

[0105] (5) Add the copolymer mixture to deionized water and stir for 30 min to obtain a doubly crosslinked acrylic secondary dispersion.

[0106] Preparation Example VIII

[0107] A doubly crosslinked acrylic secondary dispersion with a solids content of about 45% (the solids content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxydicarbonate), including a copolymer mixture and 2600 g of water. The copolymer mixture includes 380 g of the secondary amine group prepolymer, 280 g of ethyl ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 890 g of methyl methacrylate, 453 g of n-butyl acrylate, 200 g of n-butyl methacrylate, and 130 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 35 g of methyl methacrylate, 60 g of n-butyl acrylate, 200 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid. The initiator includes 62 g of tert-butyl 2-ethylhexyl peroxydicarbonate and 31 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0108] (1) Add 61 g of ethanolamine and 75 g of 2-methoxyethylamine to a 1 L reaction vessel, heat up to 50 °C, and slowly add 760 g of trimethylolpropane triacrylate dropwise. After the addition is complete, keep the temperature for 24 - 48 hours, and detect the primary amine value in the reaction system. When the primary amine value is less than 4 mg KOH / g, it is determined that the reaction is complete to obtain the secondary amine group prepolymer with an amine value of 151.4 mg KOH / g and a hydroxyl value of 75.7 mg KOH / g.

[0109] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether to a 5 L reaction vessel. Keep the temperature in the reaction vessel at 125 °C. Premix the first mixed monomer and then add it dropwise into the reaction vessel at a constant speed, and at the same time add the initiator dropwise. The addition is completed in 3 h. The first mixed monomer copolymerizes under the action of the initiator to form a copolymer with a hydroxyl value of 33.3 mg KOH / g and an acid value of 0 mg KOH / g.

[0110] (3) Keep the temperature in the reaction vessel at 125 °C. Premix the second mixed monomer and then add it dropwise into the reaction vessel at a constant speed, and at the same time add the initiator dropwise. The addition is completed in 1.5 h. The initiator is added dropwise within 5 h. The second mixed monomer copolymerizes under the action of the initiator to form a copolymer with a hydroxyl value of 222.5 mg KOH / g and an acid value of 182.2 mg KOH / g.

[0111] (4) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine to the reaction vessel, and continue to stir at 100 °C for 30 min to obtain the copolymer mixture.

[0112] (5) Add the copolymer mixture to deionized water and stir for 30 min to obtain a double-crosslinked acrylic secondary dispersion.

[0113] Preparation Example IX

[0114] A double-crosslinked acrylic secondary dispersion with a solids content of about 45% (the solids content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxyacid), including a copolymer mixture and 2600 g of water. The copolymer mixture includes 380 g of the secondary amine group prepolymer, 280 g of ethyl ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 502 g of methyl methacrylate, 391 g of n-butyl acrylate, 200 g of n-butyl methacrylate, and 580 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 60 g of methyl methacrylate, 50 g of n-butyl acrylate, 200 g of 2-hydroxyethyl methacrylate, and 75 g of acrylic acid. The initiator includes 62 g of tert-butyl 2-ethylhexyl peroxyacid and 31 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0115] (1) Add 115 g of D-230 polyetheramine and 100 g of M-1000 polyetheramine, both from Huntsman Corporation, to a 1 L reaction vessel, heat up to 50 °C, and slowly add 255 g of 1,6-hexanediol diacrylate dropwise. After the addition is complete, keep the temperature for 24 - 48 hours and measure the primary amine value in the reaction system. When the primary amine value is less than 4 mg KOH / g, it is determined that the reaction is complete to obtain a secondary amine group prepolymer with an amine value of 131.4 mg KOH / g and a hydroxyl value of 0 mg KOH / g.

[0116] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether to a 5 L reaction vessel, maintain the temperature in the reaction vessel at 125 °C, premix the first mixed monomer and then add it dropwise into the reaction vessel at a constant speed, and at the same time add the initiator dropwise. The addition is completed in 3 h. The first mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 148.5 mg KOH / g and an acid value of 0 mg KOH / g.

[0117] (3) Maintain the temperature in the reaction vessel at 125 °C, premix the second mixed monomer and then add it dropwise into the reaction vessel at a constant speed, and at the same time add the initiator dropwise. The addition is completed in 1.5 h, and the initiator is added dropwise within 5 h. The second mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 222.5 mg KOH / g and an acid value of 151.8 mg KOH / g.

[0118] (4) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine into the reaction vessel, and continue to stir at 100 °C for 30 min to obtain a copolymer mixture;

[0119] (5) Add the copolymer mixture into deionized water and stir for dispersion for 30 min to obtain a double-crosslinked acrylic secondary dispersion.

[0120] Comparative Preparation Example 1

[0121] A conventional hydroxy acrylic secondary dispersion with a solid content of about 45% (the solid content is the total proportion of the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxyacid), including a copolymer mixture and 2100 g of water. The copolymer mixture includes 280 g of ethyl 3-ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 520 g of methyl methacrylate, 319 g of n-butyl acrylate, 220 g of n-butyl methacrylate, and 350 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 157 g of methyl methacrylate, 150 g of n-butyl acrylate, 250 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid; the initiator includes 64 g of tert-butyl 2-ethylhexyl peroxyacid and 32 g of propylene glycol methyl ether; its preparation method includes the following steps:

[0122] (1) Add ethyl 3-ethoxypropionate and propylene glycol methyl ether into a 5 L reaction vessel, maintain the temperature in the reaction vessel at 125 °C, premix the first mixed monomer and then uniformly drop it into the reaction vessel, and at the same time drop the initiator. The dropping is completed in 3 h. The first mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 106.4 mg KOH / g and an acid value of 0 mg KOH / g;

[0123] (2) Maintain the temperature in the reaction vessel at 125 °C, premix the second mixed monomer and then uniformly drop it into the reaction vessel, and at the same time drop the initiator. The dropping is completed in 1.5 h, and the initiator is dropped in 5 h. The second mixed monomer undergoes a copolymerization reaction under the action of the initiator to form a copolymer with a hydroxyl value of 165.5 mg KOH / g and an acid value of 108.4 mg KOH / g;

[0124] (3) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine into the reaction vessel, and continue to stir at 100 °C for 30 min to obtain a copolymer mixture;

[0125] (4) Add the copolymer mixture into deionized water and stir for dispersion for 30 min to obtain a double-crosslinked acrylic secondary dispersion.

[0126] Comparative Preparation Example 2

[0127] A conventional hydroxyl acrylic secondary dispersion with a solid content of about 45% (the solid content is the total proportion of the first monomer, the second monomer, and tert-butyl peroxy-2-ethylhexanoate), including a copolymer mixture and 2100 g of water. The copolymer mixture includes 280 g of ethyl ethoxypropionate, 120 g of propylene glycol methyl ether, a first mixed monomer, a second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 508 g of methyl methacrylate, 385 g of n-butyl acrylate, 200 g of n-butyl methacrylate, and 580 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 35 g of methyl methacrylate, 60 g of n-butyl acrylate, 200 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid. The initiator includes 62 g of tert-butyl peroxy-2-ethylhexanoate and 31 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0128] (1) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether into a 5-L reaction vessel. The temperature in the reaction vessel is maintained at 125°C. Premix the first mixed monomer and then drop it into the reaction vessel at a constant speed while dropping the initiator. The dropping is completed in 3 h. The first mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 148.4 mg KOH / g and an acid value of 0 mg KOH / g;

[0129] (2) The temperature in the reaction vessel is maintained at 125°C. Premix the second mixed monomer and then drop it into the reaction vessel at a constant speed while dropping the initiator. The dropping is completed in 1.5 h. The initiator is dropped in within 5 h. The second mixed monomer undergoes copolymerization under the action of the initiator to form a copolymer with a hydroxyl value of 222.5 mg KOH / g and an acid value of 182.2 mg KOH / g;

[0130] (3) Continue to stir at 125°C for 2 h, then cool to 100°C. Add 111 g of dimethylethanolamine into the reaction vessel and continue to stir at 100°C for 30 min to obtain a copolymer mixture;

[0131] (4) Add the copolymer mixture into deionized water and stir and disperse for 30 min to obtain a double-crosslinked acrylic secondary dispersion.

[0132] Comparative Preparation Example Three

[0133] A dual-crosslinked acrylic secondary dispersion with a solids content of approximately 45% (the solids content is the total proportion of the secondary amine group prepolymer, the first monomer, the second monomer, and tert-butyl 2-ethylhexyl peroxyacid), including a copolymerization mixture and 2600 g of water. The copolymerization mixture includes 380 g of the secondary amine group prepolymer, 280 g of ethyl 3-ethoxypropionate, 120 g of propylene glycol methyl ether, the first mixed monomer, the second mixed monomer, an initiator, and 111 g of dimethylethanolamine. The first mixed monomer includes 520 g of methyl methacrylate, 319 g of n-butyl acrylate, 220 g of n-butyl methacrylate, and 350 g of 2-hydroxyethyl methacrylate. The second mixed monomer includes 157 g of methyl methacrylate, 150 g of n-butyl acrylate, 250 g of 2-hydroxyethyl methacrylate, and 90 g of acrylic acid. The initiator includes 64 g of tert-butyl 2-ethylhexyl peroxyacid and 32 g of propylene glycol methyl ether. Its preparation method includes the following steps:

[0134] (1) Add 340 g of 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane (IPDA) to a 1 L reaction vessel, heat up to 50 °C, and slowly dropwise add 465 g of 1,6-hexanediol diacrylate. After the addition is complete, keep the temperature for 24 - 48 hours, and detect the primary amine value in the reaction system. When the primary amine value is greater than 4 mgKOH / g and between 20 - 30 mgKOH / g, it is determined that the reaction is complete, and the secondary amine group prepolymer is obtained, with an amine value of 139.4 mgKOH / g and a hydroxyl value of 0 mgKOH / g.

[0135] (2) Add the secondary amine group prepolymer, ethyl 3-ethoxypropionate, and propylene glycol methyl ether into a 5 L reaction vessel, maintain the temperature in the reaction vessel at 125 °C, premix the first mixed monomer and then drop it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator, and finish the addition in 3 h.

[0136] (3) Maintain the temperature in the reaction vessel at 125 °C, premix the second mixed monomer and then drop it into the reaction vessel at a constant speed, and at the same time dropwise add the initiator, and finish the addition in 1.5 h. The initiator is added dropwise within 5 h.

[0137] (4) Continue to stir at 125 °C for 2 h, then cool to 100 °C, add 111 g of dimethylethanolamine to the reaction vessel, and continue to stir at 100 °C for 30 min to obtain the copolymerization mixture.

[0138] (5) Add the copolymerization mixture to deionized water and stir and disperse for 30 min to obtain the dual-crosslinked acrylic secondary dispersion.

[0139] Examples 1 - 6 and Comparative Examples 1 and 3

[0140] An aqueous two-component polyurethane color paint, comprising component A and component B. Component A includes 60 kg of the double-crosslinked acrylic secondary dispersion of Preparation Examples 1-6 or Comparative Preparation Example 1, 3, 2 kg of ethylene glycol monobutyl ether (BCS), 2 kg of dipropylene glycol monobutyl ether (DPNB), 0.2 kg of N,N-dimethylethanolamine, 0.2 kg of BYK 011 defoamer, 0.1 kg of BYK 331 leveling agent, 0.2 kg of Tego 270 wetting agent, 0.8 kg of Rheolate 299 thickener, 20 kg of R996 titanium dioxide from DuPont, 0.5 kg of BYK 190 dispersant, and 14 kg of deionized water; Component B includes 3.5 kg of propylene glycol monomethyl ether acetate (PMA) and 14 kg of hexamethylene diisocyanate (HDI) curing agent, and the curing agent is specifically Bayhydur XP2655 from Covestro.

[0141] Examples 7-9 and Comparative Example 2

[0142] An aqueous two-component polyurethane color paint, comprising component A and component B. Component A includes 60 kg of the double-crosslinked acrylic secondary dispersion of Preparation Examples 7-9 or Comparative Preparation Example 2, 2 kg of ethylene glycol monobutyl ether (BCS), 2 kg of dipropylene glycol monobutyl ether (DPNB), 0.2 kg of N,N-dimethylethanolamine, 0.2 kg of BYK 011 defoamer, 0.1 kg of BYK 331 leveling agent, 0.2 kg of Tego 270 wetting agent, 0.8 kg of Rheolate 299 thickener, 20 kg of R996 titanium dioxide from DuPont, 0.5 kg of BYK 190 dispersant, and 14 kg of deionized water; Component B includes 4.7 kg of propylene glycol monomethyl ether acetate (PMA) and 17 kg of hexamethylene diisocyanate (HDI) curing agent, and the curing agent is specifically Bayhydur XP2655 from Covestro.

[0143] The preparation method of the above-mentioned aqueous two-component polyurethane color paint comprises the following steps:

[0144] (1) Add half of the double-crosslinked acrylic secondary dispersion, N,N-dimethylethanolamine, BYK 190 dispersant, half of the BYK 011 defoamer, R996 titanium dioxide from DuPont, and 8 kg of deionized water into a grinder in sequence, and grind to obtain a mixture with a fineness less than 10 μm;

[0145] (2) Subsequently, add the remaining double-crosslinked acrylic secondary dispersion, the remaining deionized water, the remaining BYK 011 defoamer, Tego 270 wetting agent, BYK 331 leveling agent, dipropylene glycol monobutyl ether (DPNB), ethylene glycol monobutyl ether (BCS), and Rheolate 299 thickener in sequence, and disperse evenly to obtain component A;

[0146] (3) Mix propylene glycol methyl ether acetate (PMA) and hexamethylene diisocyanate (HDI) curing agent evenly to obtain Component B.

[0147] Performance detection test

[0148] I. Characterize and test the products obtained from each preparation example and comparative preparation example. The test results are shown in Table 1 below, and the test methods are as follows:

[0149] (1) Observe the appearance of each sample by visual inspection.

[0150] (2) Take 1 g of the sample, dry it at 125 °C for 1 hour, then detect the weight of the dried sample and calculate the non-volatile content of the sample.

[0151] (3) In an environment at 25 °C, use a rotary viscometer to test the viscosity of each sample.

[0152] (4) Use titration to detect the acid value of the sample, and further test the theoretical OH content and amine value relative to 100% solid content. Theoretical OH content = secondary amine group prepolymer hydroxyl content * solid content ratio + first monomer hydroxyl content * solid content ratio + second monomer hydroxyl content * solid content ratio.

[0153] (5) Use a laser particle size analyzer to detect the average particle size of the sample.

[0154] (6) Dilute the sample with deionized water at a mass ratio of 1:4, and then use a pH meter to detect the pH value of the diluted sample.

[0155] (7) Place the sample in a drying oven at 50 °C and store it for 30 days, then observe the appearance of the sample.

[0156] Table 1 - Characterization test results of samples from preparation examples and comparative preparation examples of this application

[0157]

[0158]

[0159] II. Characterize and test the waterborne two-component polyurethane color paints obtained from the examples and comparative examples. The test results are shown in Table 2 below, and the test methods are as follows:

[0160] (1) Pot life (activation period): Examine the pot life by observing or detecting the changes in coating viscosity, particle size, film appearance and gloss, and chemical resistance by professionals at different storage times under the condition of 25 °C.

[0161] (2) VOC content: tested in accordance with GB / T23986 standard, using Agilent 8860 gas chromatograph.

[0162] Table 2 - Characterization results of examples and comparative examples

[0163]

[0164]

[0165] 3. Characterization test was performed on the paint film formed after the paint of the embodiment and comparative example was applied. Component A and component B in the water-based two-component polyurethane paint of the embodiment or comparative example were mixed and stirred evenly, and then 15% of the total weight of deionized water was added, and the spraying viscosity of the system was adjusted to 24" (DIN4 cup, 25°C), and then sprayed onto the tinplate, the construction temperature was 25°C, the construction humidity was 55%, and the surface was dried at room temperature for 10 minutes to form a white paint coating; the tinplate coated with the paint coating was placed at 80°C for 30 minutes and cured at room temperature for 7 days to obtain a sample coated with a paint film (thickness of 45μm). The test results are shown in Table 3 below, and the test method is as follows:

[0166] (1) Adhesion: Tested according to GB / T 9286-1998, using BGD502 produced by Guangzhou Biaogeda Co., Ltd.

[0167] (2) Actual drying time (hard drying time): tested in accordance with GB / T1728-1979 (1989), using the cotton ball pressing method;

[0168] (3) Impact resistance test: Tested in accordance with GB / T 1732-1993, using the BGD 304 paint film impactor produced by Guangzhou BGD Co., Ltd.

[0169] (4) Water resistance: Tested in accordance with GB / T1733-93. At room temperature, the sample was sealed with 3M 600 tape and then immersed in 40°C water. The paint film was observed and the blistering time was recorded.

[0170] (5) Acid resistance: Tested in accordance with GB / T9274-88. At room temperature, the sample was sealed with 3M 600 tape and then immersed in a 5% H2SO4 solution. The paint film was observed and the bubbling time was recorded.

[0171] (6) Alkali resistance: Tested in accordance with GB / T9274-88. At room temperature, the sample was sealed with 3M 600 tape and then immersed in a 5% NaOH solution. The paint film was observed and the bubbling time was recorded.

[0172] (7) Gasoline resistance: Determined according to the method of GB / T9274-88. At room temperature, after the sample board is sealed at the edges with 3M Company's No. 600 tape, it is immersed in gasoline, the paint film is observed, and the blistering time is recorded;

[0173] (8) Resistance to artificial aging: Tested according to GB / T23987-2009. Tested with the QUV / se type ultraviolet accelerated aging test machine of the American Q-Panel Company, UVB aging, UVB-313nm lamp tube, 4h of ultraviolet irradiation, 4h of condensation.

[0174] Table 3 - Characterization results of the paint films after the color paints in the examples and comparative examples of this application are applied

[0175]

[0176] Combined with the test results of Example 1 and Comparative Example 1 in Tables 1-3, it can be seen that since Example 1 contains a secondary amine group prepolymer, which provides secondary amine groups, and the secondary amine and hydroxyl group react with isocyanate simultaneously for crosslinking. Compared with the paint film of Comparative Example 1 without the addition of the secondary amine group prepolymer, it shows a short dry time, rapid hardness establishment, high crosslinking density, good adhesion to various substrates, and excellent water resistance, chemical resistance and weather resistance.

[0177] Combined with the test results of Example 7 and Comparative Example 2 in Tables 1-3, it can be seen that since Example 7 contains a secondary amine group prepolymer, which provides secondary amine groups, and the secondary amine and hydroxyl group react with isocyanate simultaneously for crosslinking. Compared with the paint film of Comparative Example 2 without the addition of the secondary amine group prepolymer, it shows a short dry time, rapid hardness establishment, high crosslinking density, good adhesion to various substrates, and excellent water resistance, chemical resistance and weather resistance.

[0178] Combined with the test results of Examples 1-4 in Tables 1-3, it can be seen that in Examples 1-4, cyclic primary amines are used to prepare the secondary amine group prepolymer, and the content of the secondary amine group prepolymer is gradually increased. Its pot life shows a downward trend, indicating that the crosslinking activity of the secondary amine group is higher than that of the hydroxyl group; at the same time, with the increase of the secondary amine group prepolymer, the water resistance, acid resistance, alkali resistance and gasoline resistance of the paint film after the dispersion is applied are gradually improved.

[0179] Combined with the test results of Examples 4-6 and 7-9 in Table 1-3, it can be seen that in Example 4, a cyclic primary amine was used to prepare a secondary amine group prepolymer; in Example 7, a mixed cyclic primary amine was used to prepare a secondary amine group prepolymer; in Example 5, a cyclic amine-free was used to prepare a secondary amine group prepolymer; in Example 8, a mixed cyclic amine-free was used to prepare a secondary amine group prepolymer; in Example 6, a polyetheramine was used to prepare a secondary amine group prepolymer; in Example 9, a mixed polyetheramine was used to prepare a secondary amine group prepolymer. Finally, the film activation period, acid resistance, alkali resistance, and gasoline resistance of Example 4 were better than those of Examples 5-6, and the film activation period, acid resistance, alkali resistance, and gasoline resistance of Example 7 were better than those of Examples 8-9. This shows that the activity of cyclic amines is lower than that of cyclic amine-free and polyetheramines. Cyclic amines can extend the activation period while ensuring that the film has excellent water resistance, weather resistance, and improved chemical resistance.

[0180] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. In particular, for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dual-crosslinked acrylic secondary dispersion, characterized in that, Comprising a copolymer and water, the solid content of the double-crosslinked acrylic dispersion is greater than 38 wt%, and the copolymer comprises the following components in parts by weight: 240 - 900 parts of a secondary amine group prepolymer, 250 - 500 parts of a solvent, 1000 - 1800 parts of a first mixed monomer, 300 - 720 parts of a second mixed monomer, 60 - 120 parts of an initiator, and 90 - 120 parts of a neutralizing agent; The secondary amine group prepolymer is prepolymerized from 13 wt% - 49 wt% of a polybasic primary amine and 51 wt% - 87 wt% of a polyfunctional acrylate monomer, and the primary amine value of the secondary amine group prepolymer is less than 4 mgKOH / g; The first mixed monomer comprises the following components: 62 wt% - 95 wt% of a (meth)acrylate monomer and 5 wt% - 38 wt% of a hydroxyl-functional monomer; The second mixed monomer comprises the following components: 26 wt% - 56 wt% of a hydroxyl-functional monomer, 10 wt% - 25 wt% of a carboxyl-functional monomer, and the balance of a (meth)acrylate monomer.

2. The dual-crosslinked acrylic secondary dispersion according to claim 1, wherein The double-crosslinked acrylic dispersion has a hydroxyl value of 45 - 160 mgKOH / g, an acid value of 20 - 32 mgKOH / g, and an amine value of 16 - 66 mgKOH / g based on 100% solid content.

3. A dual-crosslinked acrylic secondary dispersion according to claim 1, wherein, Satisfying at least one of the following a) - f): a) The (meth)acrylate monomer includes at least one of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate; b) The hydroxyl-functional monomer includes at least one of 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, and 2-hydroxybutyl methacrylate; c) The carboxyl-functional monomer includes at least one of acrylic acid, methacrylic acid, itaconic acid, β-carboxyethyl acrylate, crotonic acid, fumaric acid, maleic acid, and maleic anhydride; d) The polyfunctional acrylate monomer is a difunctional acrylate monomer and / or a trifunctional acrylate monomer; e) The polybasic primary amine is a mono-primary amine, a di-primary amine, or a polyetheramine; f) The initiator includes at least one of tert-butyl 2-ethylhexylperoxide, tert-amyl 2-ethylhexylperoxide, tert-butyl peroxybenzoate, and tert-amyl peroxybenzoate.

4. A dual-crosslinked acrylic secondary dispersion as described in claim 1, wherein The molar ratio of the neutralizing agent to the carboxyl-functional monomer is (1.1 - 1.2):1, and the neutralizing agent is an organic amine and / or a water-soluble inorganic base.

5. A dual-crosslinked acrylic secondary dispersion as described in claim 1, wherein, The solvent includes 30 wt% - 95 wt% of a hydrophobic solvent and 5 wt% - 95 wt% of a water-soluble solvent. The hydrophobic solvent includes one of xylene, toluene, naphtha, aliphatic ester, aliphatic hydrocarbon, and aromatic hydrocarbon; the water-soluble solvent includes at least one of ethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol monobutyl ether, and dipropylene glycol monobutyl ether.

6. A dual-crosslinked acrylic secondary dispersion according to claim 1, wherein, The preparation method of the secondary amine group prepolymer is as follows: heat the polyamine to 20°C - 80°C, stir and slowly add a polyfunctional acrylate monomer dropwise. After the addition is completed, keep the temperature for 24 - 48 h. Test until the primary amine value is less than 4 mg KOH / g, then the reaction is completed.

7. The dual-crosslinked acrylic secondary dispersion according to claim 3, wherein Meet at least one of the following a) - d): a) The polyfunctional acrylic monomer includes at least one of 1,6 - hexanediol diacrylate, ethoxylated 1,6 - hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, 3 - ethoxy - trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate; b) The primary amine includes at least one of ethanolamine, methylamine, ethylamine, n - propylamine, isopropylamine, n - butylamine, isobutylamine, sec - butylamine, tert - butylamine, n - pentylamine, n - hexylamine, n - octylamine, 2 - ethylhexylamine, dodecylamine, tetradecylamine, octadecylamine, eicosylamine, 2 - methoxyethylamine, 2 - ethoxyethylamine, 3 - methoxypropylamine, 3 - ethoxypropylamine, 2 - methylthioethylamine, cyclopropylamine, cyclopentylamine, cyclohexylamine, cyclohexylmethylamine, allylamine, propargylamine, benzylamine, phenethylamine, 3 - phenyl - 1 - propylamine, 4 - phenyl - 1 - butylamine, 2 - aminomethylpyridine, aminopyridine, aniline, and naphthylamine; c) The diamine includes at least one of ethylenediamine, 1,2 - diaminopropane, 1,4 - diaminobutane, 1,5 - diaminopentane, 1,6 - diaminohexane, 1,5 - diamino - 2 - methylpentane, 2,5 - diamino - 2,5 - dimethylhexane, 2,2,4 - trimethyl - 1,6 - diaminohexane, 2,4,4 - trimethyl - 1,6 - diaminohexane, 1,1 - diaminoundecane, 1,12 - diaminododecane, 1 - amino - 3,3,5 - trimethyl - 5 - aminomethylcyclohexane, 2,4 - hexahydrotoluenediamine, 2,6 - hexahydrotoluenediamine, isopropyl - 2,4 - diaminocyclohexane, isopropyl - 2,6 - diaminocyclohexane, 1,3 - bis(aminomethyl)cyclohexane, 3,3'-dimethyl - 4,4'-diaminodicyclohexylmethane, diaminodicyclohexylmethane, 3(4) - aminomethyl - 1 - methylcyclohexylamine, 1,3 - bis(aminomethyl)benzene, m - xylylenediamine, 2,4 - diaminotoluene, 2,6 - diaminotoluene, 2,4'-diaminodiphenyl - methane, 4,4'-diaminodiphenyl - methane; d) The polyetheramine includes at least one of M - 600, M - 1000, M - 2070, M - 3080, D - 230, D - 400 from Huntsman Jeffamine series; 8. A method for preparing a double-crosslinked acrylic secondary dispersion according to any one of claims 1-7, characterized in that, Include the following steps: (1) After mixing the secondary amine group prepolymer and the solvent, the first mixed monomer and the second mixed monomer are successively added dropwise. The initiator is added dropwise synchronously with the first mixed monomer and the second mixed monomer. The temperature during the dropping process is maintained at 120°C - 130°C. After the dropping is completed, it is kept warm and stirred for 2h - 4h, cooled to 95°C - 105°C, and the neutralizing agent is added, and it is kept warm and stirred for 20min - 40min to obtain a copolymer. (2) The copolymer and water are mixed and dispersed evenly to obtain a double-crosslinked acrylic secondary dispersion.

9. Use of a double-crosslinked acrylic secondary dispersion as described in any one of claims 1 - 7 in the field of preparing waterborne coatings.

10. An aqueous two-component polyurethane coating, characterized in that, Using a double-crosslinked acrylic secondary dispersion as described in any one of claims 1 - 7, including component A and component B. By total mass percentage, component A includes 50wt% - 70wt% double-crosslinked acrylic secondary dispersion, 10wt% - 15wt% water, 3wt% - 8wt% cosolvent, and the balance of additives. The additives include at least one of pH regulator, wetting agent, dispersant, leveling agent, defoaming agent, thickening agent, catalyst, anti-settling agent, pigment and filler; component B includes 14wt% - 17wt% isocyanate curing agent and 3wt% - 6wt% cosolvent.

Images