Water-based two-component primer for melamine substrate as well as preparation method and use method of water-based two-component primer

Abstract

The invention relates to the technical field of coatings, in particular to the field of IPC C09D175, and more particularly relates to a water-based two-component primer for a melamine substrate and a preparation and use method of the water-based two-component primer. Comprising a component A and a component B. The component A is prepared from, by weight, 5-20% of acrylic emulsion, 20-35% of polyurethane emulsion, 10-25% of deionized water, 20-35% of filler, 1-5% of rheological agent, 0.5-2% of defoaming agent and the balance auxiliaries. And the component B comprises a water dispersion type isocyanate curing agent. According to the preparation method, the specific defoaming agent is matched with a proper amount of rheological additive, so that the coating has the characteristics of strong defoaming performance and low possibility of sagging in a thick coating process in the construction process. And meanwhile, the main emulsion with excellent performance is selected, so that the coating has an ultra-long activation period, quick-drying property and good adhesive force on various substrates.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to the field of IPC C09D175, and more specifically to a water-based two-component primer for melamine substrates and a preparation method and use method thereof. Background Art

[0002] At present, unsaturated polyester furniture paint is developing very rapidly, especially in the decorative coating of kitchen cabinets, bathroom, display cabinets and other furniture. Most of the white unsaturated polyester primers on the market are painted by machine spraying. The gas and oil output during machine spraying are very large, so higher requirements are put forward for the elimination of bubbles and anti-sagging performance during the construction process.

[0003] Chinese invention patent CN104497812A discloses an unsaturated polyester primer for melamine substrates without sanding and a preparation method thereof, which is prepared by mixing a main paint, an initiator, and an accelerator in a weight ratio of 100:1.0-1.2:1.2-1.4, wherein the main paint, the initiator, and the accelerator are respectively prepared by the following components and weight proportions. The unsaturated polyester primer for melamine substrates without sanding prepared by the invention does not need to sand the substrate when applied to the melamine substrate, can be directly sprayed, and has excellent adhesion and fullness after spraying, but no further research has been conducted on the bubble elimination and anti-sagging properties. Summary of the invention

[0004] The first aspect of the present invention provides a water-based two-component primer for melamine substrates, comprising a component A and a component B. The component A comprises, by weight percentage, 5-20% of acrylic emulsion, 20-35% of polyurethane emulsion, 10-25% of deionized water, 20-35% of filler, 1-5% of rheological agent, 0.5-2% of defoamer, and the balance is made up of auxiliary agents; the component B comprises a water-dispersible isocyanate curing agent.

[0005] Preferably, the water-dispersible isocyanate curing agent is selected from one of the following models of Covestro: 305CN, 307 / 1, 2655.

[0006] The weight ratio of the acrylic emulsion to the polyurethane emulsion is 1:(2-4).

[0007] The research of this application found that the weight ratio of acrylic emulsion to polyurethane emulsion is 1: (2-4), which can improve the impact resistance and bending resistance of the paint film. It may be that hydrogen bonding and van der Waals force will occur between acrylic emulsion and polyurethane emulsion, thereby improving the performance of the coating. Hydroxypropylene dispersion is added to traditional primers to improve the adhesion performance of the system, but the dispersion of hydroxypropylene dispersion and inorganic substances such as fillers in the system is poor. The applicant accidentally discovered that selecting a polyurethane emulsion with a viscosity of no more than 1000cps at 25°C and limiting the weight ratio of acrylic emulsion to polyurethane emulsion to 1: (2-3) can reduce the material composition while improving the surface dryness and actual dryness of the paint film, improving the anti-cracking performance and viscosity stability. It may be that the interaction and arrangement of acrylic emulsion and polyurethane emulsion in the film formation process under a specific addition ratio form a coating with a special sandwich structure.

[0008] Preferably, the weight ratio of the acrylic emulsion to the polyurethane emulsion is 1:(2-3).

[0009] Further preferably, the weight ratio of the acrylic emulsion to the polyurethane emulsion is 1:(2.5-3).

[0010] More preferably, the weight ratio of the acrylic emulsion to the polyurethane emulsion is 1:2.9.

[0011] The viscosity of the polyurethane emulsion at 25° C. is not higher than 1000 cps.

[0012] Preferably, the viscosity of the polyurethane emulsion at 25° C. is not higher than 500 cps.

[0013] The filler comprises titanium dioxide, talcum powder and calcium carbonate powder, and the weight ratio of the titanium dioxide, talcum powder and calcium carbonate powder is (8-20): (8-12): (5-10).

[0014] Preferably, the weight ratio of titanium dioxide, talcum powder and calcium carbonate powder is 15:(8-12):(5-10).

[0015] Further preferably, the weight ratio of titanium dioxide, talcum powder and calcium carbonate powder is 15:10:8.

[0016] Preferably, the titanium dioxide comprises rutile crystalline titanium dioxide.

[0017] Preferably, the mesh size of the talcum powder and calcium carbonate powder is 1000-4000 mesh.

[0018] Preferably, the mesh size of the talcum powder and calcium carbonate powder is 1000-3000 mesh.

[0019] Further preferably, the calcium carbonate powder comprises heavy calcium carbonate powder.

[0020] The defoaming agent includes a non-silicon defoaming agent and an organosilicon defoaming agent.

[0021] Preferably, the non-silicon defoaming agent includes at least one of AFN-140T, BYK-LPD21651, and Uniqfoam 182w.

[0022] Preferably, the organosilicon defoamer comprises an organosilicone polyether copolymer, preferably at least one of the following models: Tego902W, Tego825, Tego904W.

[0023] The rheological agent includes a montmorillonite clay rheological agent, and the preferred model is an aqueous solution prepared from Bentone LT or Deqian DE.

[0024] The weight ratio of the defoamer to the rheological agent is 1:(1.5-3).

[0025] Preferably, the weight ratio of the defoaming agent to the rheological agent is 1:(2-3).

[0026] Further preferably, the weight ratio of the defoaming agent to the rheological agent is 1:2.

[0027] The auxiliary agent includes at least one of a wetting agent, a pH adjusting agent, a leveling agent, a dispersant, a film-forming agent, a bactericide and a thickener.

[0028] The bactericide includes an organic titanate complex, preferably at least one of the following types of Hoffmann: AA, GBA, GBO, AA-75, AA-65, AA-105, DC, BEAT, BTP, TE, TnBT, KTM, TOT, TPT.

[0029] Preferably, the wetting agent includes at least one of the following types: BYK190, SN-1710, SN-1729.

[0030] Preferably, the wetting agent comprises at least one of the following types: SN-1710 and / or SN-1729.

[0031] The pH adjuster includes at least one of tris(hydroxymethyl)aminomethane (TRISAMINO), 2-amino-2-methyl-1,3-propanediol (AMPD), 2-amino-2-ethyl-1,3-propanediol (AEPD VOX 1000); 2-amino-2-methyl-1-propanol (AMP-95), 3-amino-4-octanol (CORRGUARD EXT), dimethylamino-2-methyl-1-propanol (DMAMP 80), diisopropanolamine (DIPA) and TIPA (triisopropanolamine).

[0032] Preferably, the pH adjuster includes at least one of tris(hydroxymethyl)aminomethane (TRISAMINO), 2-amino-2-methyl-1,3-propanediol (AMPD), 2-amino-2-ethyl-1,3-propanediol (AEPD VOX 1000); and 2-amino-2-methyl-1-propanol (AMP-95).

[0033] Preferably, the leveling agent includes at least one of the following types: BYK-346, BYK-345, TEGO270, TEGO4100, SURFYNOL465, SURFYNOL104E.

[0034] Further preferably, the leveling agent includes at least one of the following types: BYK-346, BYK-345, TEGO270, TEGO4100.

[0035] Preferably, the dispersant includes at least one of the following models: BYK2055, NOPCALL-5180, DISPERS-755W, greesolA04E.

[0036] The film-forming aid includes at least one of dipropylene glycol butyl ether DPnB, propylene glycol n-butyl ether PNB, dipropylene glycol methyl ether DPM, and propylene glycol phenyl ether PPH.

[0037] Preferably, the film-forming aid includes at least one of dipropylene glycol butyl ether DPnB, propylene glycol n-butyl ether PNB, and dipropylene glycol methyl ether DPM.

[0038] Preferably, the film-forming aid includes dipropylene glycol butyl ether DPnB and dipropylene glycol methyl ether DPM.

[0039] Further preferably, the weight ratio of DPnB to DPM is 1:(0.8-2).

[0040] The thickener includes at least one of the following models: Deqian 50D, Deqian 299, JETHOUS 76, and Haimingsi 350D.

[0041] Preferably, the thickener includes DEQIAN 299 and JETHOUS 76.

[0042] Further preferably, the weight ratio of Deqian 299 to JETHOUS 76 is 1:(1.5-3).

[0043] The second aspect of the present invention provides a method for preparing a water-based two-component primer for a melamine substrate, comprising the following steps:

[0044] S1, mixing deionized water accounting for 50-80% of the total amount of deionized water, a wetting agent, a non-silicon defoaming agent and a filler to obtain a first mixture;

[0045] S2, mixing the acrylic emulsion and the polyurethane emulsion evenly, adding a pH adjuster, a leveling agent, a dispersant and a silicone defoamer, and then adding a film-forming agent, deionized water accounting for 5-15% of the total amount of deionized water and a fungicide, and mixing evenly to obtain a second mixture;

[0046] S3, adding the first mixture to the second mixture, adding a rheological agent, a thickener and the remaining deionized water, and mixing well to obtain component A;

[0047] S4, mixing the raw materials of component B uniformly to obtain component B.

[0048] The third aspect of the present invention provides a method for using a water-based two-component primer for a melamine substrate, comprising the following steps: preparing a coating with a weight ratio of component A, component B and deionized water of 100:(2-8):(2-8), and spraying the coating.

[0049] Preferably, the method comprises the following steps: preparing a coating material by mixing component A, component B and deionized water in a weight ratio of 100:5:5, and spraying the coating material.

[0050] Preferably, the spraying is carried out by reciprocating spraying.

[0051] Beneficial Effects

[0052] 1. The weight ratio of acrylic emulsion to polyurethane emulsion is 1:(2-4), which can improve the impact resistance and bending resistance of the paint film.

[0053] 2. Selecting a polyurethane emulsion with a viscosity of no more than 1000cps at 25°C and limiting the weight ratio of acrylic emulsion to polyurethane emulsion to 1:(2-3) can reduce the material composition while improving the surface drying and actual drying of the paint film, and enhance the anti-cracking performance and viscosity stability.

[0054] 3. The filler includes titanium dioxide, talcum powder and calcium carbonate powder, wherein the weight ratio of the titanium dioxide, talcum powder and calcium carbonate powder is (8-20): (8-12): (5-10), which can improve the anti-rebound and leveling properties of the primer.

[0055] 4. By limiting the weight ratio of defoaming agent to rheological agent to 1:(1.5-3), the problems of difficult defoaming and easy sagging encountered during machine spraying can be solved at the same time.

[0056] 5. By adjusting the added reagents of non-silicon defoamer and silicone defoamer in the preparation process, the leveling performance and viscosity stability of the system can be simultaneously improved to ensure the normal coating of the topcoat and meet the use requirements of melamine substrates.

[0057] 6. During the use of the primer of this application, the paint film is smooth and free of bubbles, and no oil bleeding occurs when thickly applied. The paint film dries quickly and can be turned over or stacked after being placed in an environment at room temperature of 25°C for 2 hours. After the paint film is completely dry, it has good (grade 0) adhesion on the melamine substrate.

[0058] 7. After the primer of this application is dry, it is easy to polish and no pinholes will appear during the polishing process due to the failure to eliminate bubbles, which creates sufficient conditions for the subsequent spraying of topcoat. In terms of thick coating, easy polishing and no pinholes, the production and painting efficiency of the furniture factory is greatly improved. DETAILED DESCRIPTION

[0059] Example 1, Comparative Examples 1-2

[0060] A water-based two-component primer for melamine substrates, composed of component A and component B. By weight percentage, the formula of component A is shown in Table 1, and the formula of component B is shown in Table 2:

[0061] Table 1

[0062]

[0063] Table 2

[0064] Components Model(Manufacturer) Example 1 Comparative Example 1 Comparative Example 2 Solvents PMA (Jiangsu Sanmu Chemical) 29.7 29.7 29.7 Water absorbent G-180 (Shanghai Baiyin Chemical) 0.3 0.3 0.3 Curing agent 307 / 1(Covestro) 70 70 70

[0065] A water-based two-component primer for melamine substrate, wherein the preparation method of Example 1 is:

[0066] S1, add deionized water accounting for 72.1% of the total amount of deionized water filtered by a 300-mesh filter into the cylinder in a static state, start the disperser, adjust the speed to 500 rpm, add a wetting agent and a non-silicon defoaming agent in this state, and maintain the speed for dispersion for 10 minutes after the addition is completed; then increase the speed of the disperser to 800 rpm, add titanium dioxide, talcum powder, and calcium carbonate powder in turn, mix them evenly to obtain a first mixture, and after the addition is completed, use a small amount of deionized water to clean the cylinder wall to avoid powder residue; continue to increase the speed of the disperser to 1200 rpm, disperse for 25 minutes, obtain the first mixture, and place it for standby;

[0067] S2, take another cylinder and add acrylic emulsion and polyurethane emulsion in a static state and mix them evenly, increase the speed of the disperser to 1000 rpm, add pH regulator, leveling agent, dispersant and silicone defoamer in sequence, maintain the speed and disperse for 25 minutes after the addition, reduce the speed of the disperser to 800 rpm, slowly add the pre-mixed film-forming agent, deionized water accounting for 10.7% of the total amount of deionized water and fungicide into the mixture, maintain the speed and disperse for 5 minutes to obtain the first mixture, and set aside for use;

[0068] S3, while the second mixture is maintained at 800 rpm, the first mixture is added to the second mixture, the rheological agent, the thickener Deqian 299 and the remaining deionized water are added, and the mixture is evenly mixed. The cylinder wall is cleaned with deionized water, and the thickener JETHOUS 76 is added to adjust the oil body to a suitable viscosity of 85KU (Stormer viscometer / 25°C), thereby completing the preparation of the coating component A.

[0069] S4, add the solvent filtered by a 300-mesh filter in a static state, increase the speed of the disperser to 500 rpm, add a water absorbent, slowly add a curing agent, increase the speed to 900 rpm, and disperse for 15 minutes until it is uniform, thereby completing the preparation of component B.

[0070] The preparation method of Comparative Example 1 is:

[0071] S1, add deionized water accounting for 72.1% of the total amount of deionized water filtered by a 300-mesh filter into the cylinder in a static state, start the disperser, adjust the speed to 500 rpm, add a wetting agent and a non-silicon defoaming agent in this state, and maintain the speed for dispersion for 10 minutes after the addition is completed; then increase the speed of the disperser to 800 rpm, add titanium dioxide, talcum powder, and calcium carbonate powder in turn, mix them evenly to obtain a first mixture, and after the addition is completed, use a small amount of deionized water to clean the cylinder wall to avoid powder residue; continue to increase the speed of the disperser to 1200 rpm, disperse for 25 minutes, obtain the first mixture, and place it for standby;

[0072] S2, take another cylinder and add acrylic emulsion, polyurethane emulsion and hydroxypropyl dispersion in a static state and mix them evenly, increase the speed of the disperser to 1000 rpm, add pH adjuster, leveling agent, dispersant and silicone defoamer in sequence, maintain the speed and disperse for 25 minutes after the addition is completed, reduce the speed of the disperser to 800 rpm, slowly add the pre-mixed film-forming agent, deionized water accounting for 10.7% of the total amount of deionized water and fungicide into the mixed solution, maintain the speed and disperse for 5 minutes to obtain the first mixture, and set aside for use;

[0073] S3, while the second mixture is maintained at 800 rpm, the first mixture is added to the second mixture, the rheological agent, the thickener Deqian 299 and the remaining deionized water are added, and the mixture is evenly mixed. The cylinder wall is cleaned with deionized water, and the thickener JETHOUS 76 is added to adjust the oil body to a suitable viscosity of 85KU (Stormer viscometer / 25°C), thereby completing the preparation of the coating component A.

[0074] S4, add the solvent filtered by a 300-mesh filter in a static state, increase the speed of the disperser to 500 rpm, add a water absorbent, slowly add a curing agent, increase the speed to 900 rpm, and disperse for 15 minutes until it is uniform, thereby completing the preparation of component B.

[0075] The preparation method of Comparative Example 2 is:

[0076] S1, add deionized water accounting for 72.1% of the total amount of deionized water filtered by a 300-mesh filter into a cylinder in a static state, start the disperser, adjust the speed to 500 rpm, add a wetting agent in this state, and maintain the speed for dispersion for 10 minutes after the addition is completed; then increase the speed of the disperser to 800 rpm, add titanium dioxide, talcum powder, and calcium carbonate powder in turn, mix them evenly to obtain a first mixture, and after the addition is completed, use a small amount of deionized water to clean the cylinder wall to avoid powder residue; continue to increase the speed of the disperser to 1200 rpm, disperse for 25 minutes, obtain a first mixture, and place it for standby;

[0077] S2, take another tank and add acrylic emulsion and polyurethane emulsion in a static state and mix them evenly, increase the speed of the disperser to 1000 rpm, add pH regulator, non-silicon defoamer, leveling agent, dispersant and silicone defoamer in sequence, maintain the speed and disperse for 25 minutes after the addition is completed, reduce the speed of the disperser to 800 rpm, slowly add the pre-mixed film-forming agent, deionized water accounting for 10.7% of the total amount of deionized water and fungicide into the mixed solution, maintain the speed and disperse for 5 minutes to obtain the first mixture, and set aside for use;

[0078] S3, while the second mixture is maintained at 800 rpm, the first mixture is added to the second mixture, the rheological agent, the thickener Deqian 299 and the remaining deionized water are added, and the mixture is evenly mixed. The cylinder wall is cleaned with deionized water, and the thickener JETHOUS 76 is added to adjust the oil body to a suitable viscosity of 85KU (Stormer viscometer / 25°C), thereby completing the preparation of the coating component A.

[0079] S4, add the solvent filtered by a 300-mesh filter in a static state, increase the speed of the disperser to 500 rpm, add a water absorbent, slowly add a curing agent, increase the speed to 900 rpm, and disperse for 15 minutes until it is uniform, thereby completing the preparation of component B.

[0080] A method for using a water-based two-component primer for a melamine substrate comprises the following steps: preparing a coating with a weight ratio of 100:5:5 for component A, component B and deionized water, with a construction viscosity of 75″ / No. 3 cup / 25°C, and spraying with a reciprocating machine.

[0081] Performance testing methods and data

[0082] The primers prepared in the examples and comparative examples were subjected to performance tests. The test items and data are listed in Table 3. The substrate used in the test was melamine.

[0083] Table 3

[0084]

[0085] The following conclusions can be drawn from Table 3:

[0086] 1. The method of dispersing Uniqfoam 182w defoamer in white water slurry is more stable and has no risk of particles;

[0087] 2. Using UA431 to replace the conventional UA431+4002L compound reduces the material composition, while the paint film speed is faster, the anti-cracking performance is significantly improved, and the oil viscosity stability is more advantageous than Comparative Example 1.

Claims

1. A water-based two-component primer for melamine substrates, characterized in that: The invention comprises component A and component B. Component A comprises, by weight percentage, 5-20% acrylic emulsion, 20-35% polyurethane emulsion, 10-25% deionized water, 20-35% filler, 1-5% rheological agent, 0.5-2% defoamer, and the balance is made up of auxiliary agents; component B comprises a water-dispersible isocyanate curing agent.

2. The water-based two-component primer for melamine substrate according to claim 1, characterized in that: The weight ratio of the acrylic emulsion to the polyurethane emulsion is 1:(2-4).

3. The water-based two-component primer for melamine substrate according to claim 2, characterized in that: The viscosity of the polyurethane emulsion at 25° C. is not higher than 1000 cps.

4. The water-based two-component primer for melamine substrates according to claim 3, characterized in that: The filler comprises titanium dioxide, talcum powder and calcium carbonate powder, and the weight ratio of the titanium dioxide, talcum powder and calcium carbonate powder is (8-20): (8-12): (5-10).

5. The water-based two-component primer for melamine substrates according to claim 4, characterized in that: The defoaming agent includes a non-silicon defoaming agent and an organosilicon defoaming agent.

6. The water-based two-component primer for melamine substrates according to claim 5, characterized in that: The rheological agent includes a montmorillonite clay rheological agent.

7. The water-based two-component primer for melamine substrates according to claim 6, characterized in that: The weight ratio of the defoaming agent to the rheological agent is 1:(1.5-3).

8. The water-based two-component primer for melamine substrates according to claim 7, characterized in that: The auxiliary agent includes at least one of a wetting agent, a pH adjusting agent, a leveling agent, a dispersant, a film-forming agent, a bactericide and a thickener.

9. A method for preparing a water-based two-component primer for melamine substrate according to claim 8, characterized in that: The following steps are involved: S1, mixing deionized water accounting for 50-80% of the total amount of deionized water, a wetting agent, a non-silicon defoaming agent and a filler to obtain a first mixture; S2, mixing the acrylic emulsion and the polyurethane emulsion evenly, adding a pH adjuster, a leveling agent, a dispersant and a silicone defoamer, and then adding a film-forming agent, deionized water accounting for 5-15% of the total amount of deionized water and a fungicide, and mixing evenly to obtain a second mixture; S3, adding the first mixture to the second mixture, adding a rheological agent, a thickener and the remaining deionized water, and mixing uniformly to obtain component A; S4, mixing the raw materials of component B uniformly to obtain component B.

10. A method for using the water-based two-component primer for melamine substrates according to any one of claims 1 to 7, characterized in that: The following steps are involved: Mix component A, component B and deionized water according to 100: The weight ratio of (2-8):(2-8) is prepared into a coating and sprayed.

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