Acrylate hyperdispersant for preventing flooding of coating and preparation method of acrylate hyperdispersant

Abstract

The invention belongs to the field of hyperdispersants, and particularly relates to an acrylate hyperdispersant for preventing flooding of a coating and a preparation method of the acrylate hyperdispersant. The preparation method comprises the following steps: synthesizing a first functional monomer, synthesizing a second functional monomer and synthesizing the acrylate hyperdispersant. According to the acrylate hyperdispersant disclosed by the invention, a plurality of anchoring groups are provided for an inorganic pigment, an organic pigment and a carbon black pigment in a molecular structure, so that the dispersant can be well combined with pigment particles in a colored coating, and meanwhile, polyether and polyacrylate solvent chain segments are also provided, so that the stability among the particles is kept; therefore, the problem of flooding in the colored paint is effectively solved. Compared with the prior art in which a plurality of different types of dispersants are matched, the anti-floating agent has the advantages of very good anti-floating effect, simplicity and convenience in operation and wider application range.

Description

Technical Field

[0001] The invention belongs to the field of hyperdispersants, and in particular relates to an acrylate hyperdispersant for preventing color floating of coatings and a preparation method thereof. Background Art

[0002] During the production, storage and application of color coatings, the coating surface often encounters floating color and floating problems. The floating color problem will cause color difference on the paint film surface. The current methods to solve the floating color problem mainly include mechanical stirring or finding suitable resins, color pastes and additives on the market.

[0003] The method of mechanical stirring again may bring inconvenience to the construction and mechanical stirring will produce foam, thus affecting the performance of the paint film; the method of finding suitable resins, color pastes and additives on the market is time-consuming and laborious, and it is difficult to find suitable raw materials; obviously, the existing technical solutions to the floating color problem are only empirical attempts from an application perspective, and have failed to fundamentally and effectively solve the floating color and blooming problems of colored coatings during production, storage and construction.

[0004] In addition, Chinese patent CN110713770A discloses an anti-floating color coating and its preparation method, comprising the following components and raw materials in weight: 60-80 parts of acrylic resin, 8-10 parts of solvent, 2-30 parts of pigment powder, and 5-10 parts of additives. The invention forms a special interaction with the pigment powder by using a specially modified wetting dispersant, and also adjusts the thixotropy by organic modified fumed silica, so as to ensure that no floating color occurs on the basis of meeting the requirements for the use of the coating. The wetting dispersant is a high molecular weight polycarboxylic acid with a molecular weight of 1000-5000, such as Deqian 9250 high molecular weight carboxylic acid wetting dispersant; or a terminal functionalized hyperdispersant with a molecular weight between 10000-100000, such as Lubrizol 32500. The special interaction with the pigment powder mainly refers to the fact that the carboxyl group in the dispersant can generate hydrogen bonds with the polar groups on the surface of the pigment particles, and the binding force is stronger. The dispersant structure used in this patent mainly relies on the hydrogen bonding between carboxyl groups and pigment particles to enhance the binding force. Of course, for inorganic pigment particles such as titanium dioxide, iron oxide, etc., which carry hydroxyl groups on the surface, hydrogen bonding can be produced. However, for organic pigments such as azo, phthalocyanine or carbon black particles, which do not carry hydroxyl groups on the surface, hydrogen bonding cannot be produced. Therefore, for colored coatings containing both inorganic and organic pigments, the anti-floating effect of the dispersant selected by this invention is limited.

[0005] Chinese patent CN106893460A discloses an anti-floating color mid-coat, comprising the following components by weight: 4-20 parts of a first acrylic resin, 4-20 parts of a first polyester resin, 5-20 parts of a first amino resin, 0.1-2 parts of a first auxiliary agent, 5-20 parts of a first solvent, and 72.1-182 parts of a main color paste. The invention uses a wetting and dispersing auxiliary agent to enhance the wetting and dispersion of titanium dioxide in the mid-coat, increase the grinding efficiency, and fully miscible it with other color pastes, thereby solving the problem of floating color. The wetting and dispersing agent selected in the patent only emphasizes the enhancement of the wetting and dispersing effect on titanium dioxide, and the pigment particle system used only includes titanium dioxide, carbon black, and barium sulfate, but does not involve the floating color effect with other organic color pigment particles. Therefore, for color coatings containing organic pigments, the anti-floating effect of the dispersant selected in the invention is limited.

[0006] Chinese patent CN115403992A discloses a gray mid-coat paint with anti-black floating, comprising the following components by weight: 10-20 parts of linear saturated polyester resin; 10-20 parts of branched saturated polyester resin; 3-10 parts of methyl etherified amino resin; 3-10 parts of butyl etherified amino resin; 0.1-1 part of oxidized polyethylene wax; 22.1-59 parts of pigments and fillers; 7-35 parts of solvents; 0.01-1 parts of color paste; 0.1-0.5 parts of leveling agent; dispersant; wherein the dispersant contains: 0.1-1 parts of polymer dispersant and 0.1-1 parts of low molecular weight dispersant. The polymer dispersant is a solvent-based polymer dispersant, and its number average molecular weight is preferably above 8000; the number average molecular weight of the low molecular weight dispersant is less than 5000, and it is a dispersant of unsaturated polyamine amide and low molecular weight acidic polyester salt solution. The invention solves the problem of floating black by selecting a dispersant containing nitrogen atoms to enhance the bonding force with the carbon black surface, but does not address the floating color problem of color coating particles. Therefore, for color coatings containing organic pigments, the anti-floating effect of the dispersant selected by the invention is limited.

[0007] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the invention

[0008] The purpose of the present invention is to synthesize an anti-floating acrylate super dispersant from the perspective of molecular structure design to solve the floating and floating problems of color coatings during storage, and to provide a new and effective solution for solving the floating and floating problems of color coatings. The present invention believes that the fundamental reason for the floating and floating problems of color coatings is that the anchoring force between the selected dispersant and the pigment particles is not strong or the steric resistance formed between the pigment particles is not enough, resulting in the agglomeration of the particles. Therefore, a special structure dispersant is synthesized from the perspective of organic synthesis molecular structure design to solve the floating problem.

[0009] In order to solve the problems existing in the prior art, the present invention provides a method for preparing an acrylic ester hyperdispersant for preventing color floating in coatings, the preparation method comprising the following steps:

[0010] (I) Synthesis of the first functional monomer

[0011] Mixing polyethylene glycol monomethyl ether, a first polymerization inhibitor, a first catalyst, and a water-carrying agent, then heating and adding a carboxyl monomer, and after the reaction is completed, obtaining the first functional monomer;

[0012] (II) Synthesis of the second functional monomer

[0013] Methyl methacrylate, N,N-dimethylethanolamine, a second polymerization inhibitor, a second catalyst, and a methanol-carrying agent are mixed, and then heated and reacted to obtain the second functional monomer;

[0014] (III) Synthetic acrylate hyperdispersant

[0015] (III-1) mixing and stirring the carboxyl monomer, the benzene ring monomer, the first functional monomer, the second functional monomer, an initiator, a chain transfer agent and a solvent to obtain a monomer mixture;

[0016] (III-2) taking another solvent, adding the monomer mixture to the solvent and heating it to react, then sequentially performing a reduced pressure distillation process and an alkali neutralization process, and finally cooling and discharging the material to obtain the acrylic ester hyperdispersant for preventing color floating of the coating.

[0017] Preferably, in step (I):

[0018] The first inhibitor is hydroquinone or p-hydroxyanisole;

[0019] And / or, the first catalyst is p-toluenesulfonic acid;

[0020] And / or, the water-carrying agent is toluene.

[0021] Preferably, in step (I) and step (III-1), the carboxyl monomer comprises methacrylic acid or acrylic acid.

[0022] Preferably, in step (II):

[0023] The second polymerization inhibitor is hydroquinone or p-hydroxyanisole;

[0024] And / or, the second catalyst is lithium hydroxide;

[0025] And / or, the methanol-carrying agent is cyclohexane.

[0026] Preferably, in step (III-1):

[0027] The benzene ring monomer is styrene or methylstyrene;

[0028] And / or, the initiator is azobisisobutyronitrile;

[0029] And / or, the chain transfer agent is n-dodecyl mercaptan or mercaptoethanol;

[0030] And / or, the solvent is ethyl acetate.

[0031] Preferably, in step (I), the temperature is raised to 110-120°C.

[0032] Preferably, in step (II), the temperature is raised to 80-85°C.

[0033] Preferably, in step (III-2), the temperature is raised to 75-80°C for reaction.

[0034] Based on the same technical concept, another embodiment of the present invention is to provide an acrylic ester superdispersant for preventing color floating of color coatings obtained by the above preparation method.

[0035] To facilitate understanding of the present invention, the technical ideas of the present invention are explained:

[0036] Considering that the pigment particles contained in the color coating include inorganic pigments, organic pigments and carbon black pigments. Inorganic pigments are usually easy to carry hydroxyl groups on their surfaces, and their dispersants usually contain acidic functional groups that can have affinity with hydroxyl functional groups, such as carboxyl groups, hydroxyl groups, etc.; organic pigments mostly contain aromatic rings or heterocyclic structures, and aromatic ring functional groups, such as benzene rings, are introduced into the design of their dispersants to produce affinity for them; the surface of carbon black pigments is highly oxidized and acidic, and has good affinity with nitrogen-containing functional groups, and amine groups or imine groups are often introduced into the dispersant. Based on the above analysis, the inventors considered designing and preparing an anti-floating color acrylate superdispersant that contains special structures such as carboxyl groups, benzene rings and amine groups. The structure of the dispersant can be divided into two parts: an anchor group (segment A) and a solvation chain (segment B). Common anchor groups (segment A) include -R 2 、-NR 3+ 、-COOH、-COO-、-SO 3 H, -SO 3 -, polyols and polyethers, etc. They are tightly adsorbed on the surface of solid particles through interactions such as ionic bonds, covalent bonds, hydrogen bonds and van der Waals forces, preventing the hyperdispersant from desorbing. The solvated chain (B segment) is commonly found in polymer chains such as polyester, polyether, polyolefin and polyacrylate, which form an adsorption layer on the surface of the particles and stabilize the dispersion of the particles through steric hindrance.

[0037] The beneficial effects of the present invention are:

[0038] The acrylate hyperdispersant of the present invention provides multiple anchoring groups for inorganic pigments, organic pigments and carbon black pigments in the molecular structure, so that the dispersant can be well combined with the pigment particles in the color coating, and also provides polyether and polyacrylate solvent segments, so that the particles maintain stability, thereby effectively solving the floating color problem in the color coating. Compared with the prior art that uses several different types of dispersants, the advantages of the present invention are that the anti-floating effect is very good, the operation is simple and the application range is wide. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 is the chemical reaction formula in step (I) of the embodiment.

[0041] Figure 2 is the chemical reaction formula in step (II) of the example.

[0042] Figure 3 This is a photograph of the anti-floating effect of Example 1.

[0043] Figure 4 This is a photograph of the anti-floating effect of Example 2.

[0044] Figure 5 This is a photograph of the anti-floating effect of Example 3.

[0045] Figure 6 This is a photograph of the anti-floating effect of Comparative Example 1.

[0046] Figure 7 This is a photograph of the anti-floating effect of Comparative Example 2.

[0047] Figure 8 This is a photograph of the anti-floating effect of Comparative Example 3.

[0048] Fig. 9 This is a photograph of the anti-floating effect of Comparative Example 4. DETAILED DESCRIPTION

[0049] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0050] Example

[0051] (I) Synthesizing the functional monomer methoxy polyoxyethylene ether methacrylate MPEG500-MA, MAA and MPEG500 are subjected to an esterification reaction under the action of a catalyst to synthesize MPEG500-MA, the reaction formula is as follows: Figure 1 shown.

[0052] Add polyethylene glycol monomethyl ether (MPEG500), inhibitor hydroquinone, catalyst p-toluenesulfonic acid, and water-carrying agent toluene into a four-necked flask equipped with a stirrer and a thermometer, introduce nitrogen, start stirring, heat to 120°C, slowly drop methacrylic acid (MAA), and finish dropping in about 1 hour. When the material boils, the water generated by the reaction and the water-carrying agent are azeotropic and separated through a water separator. When no more water is generated, the reaction is completed. When the temperature drops to room temperature, switch the reaction device to a vacuum distillation device to remove toluene to obtain methoxy polyethylene glycol methacrylate.

[0053] The amounts of raw materials are shown in Table 1.

[0054] Table 1

[0055] Components MAA MPEG500 Hydroquinone p-Toluenesulfonic acid Toluene Dosage / g 51.6 100 0.8 1.5 50

[0056] (II) Synthesizing the functional monomer dimethylaminoethyl methacrylate (DMAEMA), DMAEMA is synthesized by transesterification reaction of MMA and DMEA under the action of a catalyst, as shown in the reaction formula: Figure 2 shown.

[0057] Methyl methacrylate (MMA), N,N-dimethylethanolamine (DMEA), inhibitor hydroquinone, catalyst lithium hydroxide, and methanol-carrying agent cyclohexane were added to a four-necked flask equipped with a stirrer and a thermometer, nitrogen was introduced, stirring was started, and after the temperature was raised to 82°C, cyclohexane continuously carried methanol to the water separator and separated methanol, and the reaction was terminated after reflux until no methanol was separated. Then, the reaction was cooled to room temperature, and the reaction device was switched to a vacuum distillation device to remove cyclohexane to obtain dimethylaminoethyl methacrylate.

[0058] The amounts of raw materials are shown in Table 2.

[0059] Table 2

[0060] Components MMA DMEA Hydroquinone Lithium hydroxide Cyclohexane Dosage / g 200 89 1 3 66

[0061] (III) Synthesis of acrylate hyperdispersant: MAA, St, MPEG500MA and DMAEMA were used to synthesize the acrylate hyperdispersant by free radical polymerization.

[0062] Add monomers MAA, St, MPEG500MA, DMAEMA, initiator AIBN, chain transfer agent n-dodecyl mercaptan and solvent ethyl acetate to a round-bottom flask in sequence, stir and mix thoroughly to prepare a monomer mixture for use. Add a certain amount of solvent ethyl acetate to a four-necked flask equipped with a stirrer and a thermometer, introduce nitrogen, start stirring, heat to 78°C, and slowly add the monomer mixture to the reactor. Control the dripping speed so that it drips in about 3 hours, add supplementary lead, and continue to keep warm for 2 hours. Remove unreacted monomers and solvent ethyl acetate at 0.1MPa vacuum and 80°C. Add deionized water and alkali solution for neutralization and dissolution for 2 hours, and discharge the material below 50°C to obtain an acrylate superdispersant.

[0063] By setting different raw material dosages for this step, different embodiments and comparative examples are obtained, as shown in Table 3.

[0064] Table 3

[0065]

[0066]

[0067] Effect verification example

[0068] Evaluation of the application effect of acrylic superdispersant for anti-floating paint in colored coatings

[0069] In a stainless steel cup, water, acrylic ester hyperdispersant (the products obtained in Examples 1 to 3 and Comparative Examples 1 to 4, respectively), wetting agent BD-405, defoaming agent TEGO810 were added in sequence, the grinding and dispersing machine was turned on, the speed was set to 500 rpm, and stirring was carried out for 10 min; the speed was increased to 2000 rpm, titanium dioxide, iron oxide yellow, phthalocyanine blue, and carbon black were slowly added in sequence, and stirring was carried out for 30 min; the mixture was transferred to a grinding cylinder, zirconium beads were added, and grinding was carried out at 2000 rpm for 60 min; the zirconium beads were filtered out, the speed was adjusted to 500 rpm, defoaming agent BYK024, acrylic resin DOWELL RA1300, PH regulator, solvent dipropylene glycol butyl ether DPnB, and thickener U605 were added in sequence, the speed was set to 600 rpm, and stirring was carried out for 30 min; the mixture was filtered through a 200-mesh filter, and the material was discharged for standby use.

[0070] Among them, the color coating formula is shown in Table 4.

[0071] Table 4

[0072] Components Dosage / g water 23 Acrylate Hyperdispersants 2 Wetting agent BD-405 0.3 Defoamer TEGO810 0.1 Titanium dioxide R-902 34 Iron oxide yellow 1.5 Phthalocyanine Blue 1.5 Carbon Black 3 Defoamer BYK024 0.1 Acrylic resin DOWELLRA1300 30 pH Adjusters 1 Dipropylene glycol butyl ether DPnB 3 Thickener U605 0.5 total 100

[0073] Place the ground slurry in a transparent beaker, store it at 40℃ for 24 hours, and observe the surface condition. The above is graded according to the state of floating color and floating: Grade 1 is no floating color and floating, Grade 5 is very serious floating color and floating, and the intermediate grades 2-4 are graded according to the severity of floating color and floating, such as Grade 2 is very slight floating color and floating, Grade 3 is slight floating color and floating, and Grade 5 is severe floating color and floating.

[0074] The anti-floating color application results of various embodiments and comparative examples are shown in Table 5.

[0075] Table 5

[0076]

[0077] The corresponding photos are as follows Figure 3 to Figure 9 shown.

[0078] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing an acrylic ester hyperdispersant for preventing floating color in coatings, characterized in that: The preparation method comprises the following steps: (I) Synthesis of the first functional monomer Mixing polyethylene glycol monomethyl ether, a first polymerization inhibitor, a first catalyst, and a water-carrying agent, then heating and adding a carboxyl monomer, and after the reaction is completed, obtaining the first functional monomer; (II) Synthesis of the second functional monomer Methyl methacrylate, N,N-dimethylethanolamine, a second polymerization inhibitor, a second catalyst, and a methanol-carrying agent are mixed, and then heated and reacted to obtain the second functional monomer; (III) Synthetic acrylate hyperdispersant (III-1) mixing and stirring the carboxyl monomer, the benzene ring monomer, the first functional monomer, the second functional monomer, an initiator, a chain transfer agent and a solvent to obtain a monomer mixture; (III-2) taking another solvent, adding the monomer mixture to the solvent and heating it to react, then sequentially performing a reduced pressure distillation process and an alkali neutralization process, and finally cooling and discharging the material to obtain the acrylic ester hyperdispersant for preventing color floating of the coating.

2. The method for preparing the acrylic ester superdispersant for preventing color floating of coatings according to claim 1, characterized in that: In step (I): The first inhibitor is hydroquinone or p-hydroxyanisole; And / or, the first catalyst is p-toluenesulfonic acid; And / or, the water-carrying agent is toluene.

3. The method for preparing the acrylic ester superdispersant for preventing color floating of coatings according to claim 1, characterized in that: In step (I) and step (III-1), the carboxyl monomer includes methacrylic acid or acrylic acid.

4. The method for preparing the acrylic ester superdispersant for preventing color floating of coatings according to claim 1, characterized in that: In step (II): The second polymerization inhibitor is hydroquinone or p-hydroxyanisole; And / or, the second catalyst is lithium hydroxide; And / or, the methanol-carrying agent is cyclohexane.

5. The method for preparing the acrylic ester superdispersant for preventing color floating of coatings according to claim 1, characterized in that: In step (III-1): The benzene ring monomer is styrene or methylstyrene; And / or, the initiator is azobisisobutyronitrile; And / or, the chain transfer agent is n-dodecyl mercaptan or mercaptoethanol; And / or, the solvent is ethyl acetate.

6. The method for preparing the acrylic ester superdispersant for preventing color floating of coatings according to claim 1, characterized in that: In step (I), the temperature is raised to 110-120°C.

7. The method for preparing the acrylic ester superdispersant for preventing color floating of coatings according to claim 1, characterized in that: In step (II), the temperature is raised to 80-85°C.

8. The method for preparing the acrylic ester superdispersant for preventing color floating of coatings according to claim 1, characterized in that: In step (III-2), the temperature is raised to 75 to 80°C for reaction.

9. Acrylate superdispersant for preventing color floating in coatings obtained by the preparation method according to any one of claims 1 to 8.

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