Water-based two-component electrostatic spraying varnish primer and preparation method thereof

Abstract

The invention discloses a water-based two-component electrostatic spraying varnish primer and a preparation method thereof. The water-based two-component electrostatic spraying varnish primer comprises a component A and a component B, the component A is prepared from 100 parts by weight of hydroxyl-containing waterborne polyurethane dispersion; 30 to 60 parts by weight of a hydroxyl-free aqueous polyurethane dispersion; 6 to 10 parts of propylene glycol monomethyl ether acetate; 10 to 20 parts of deionized water; the component B comprises the following components in parts by weight: 20-50 parts of polyisocyanate; and 5-10 parts by weight of propylene glycol methyl ether acetate. A waterborne polyurethane system adopted by the invention can have a good sealing effect on a wood material, and defects such as bubbles and pinholes are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to a water-based two-component electrostatic spray varnish primer and a preparation method thereof. Background Art

[0002] As an efficient and environmentally friendly coating method, electrostatic spraying technology is widely used in the surface treatment of various substrates. This technology uses the principle of electrostatic adsorption to make the paint particles evenly deposit on the surface of the substrate under the action of the electric field to form a smooth and uniform coating. However, in actual applications, different types of paint will show different characteristics and challenges during the electrostatic spraying process.

[0003] Due to the difference in the material quality of wood, and also because there is no covering and dispersing effect of pigment particles, water-based two-component materials are more likely to expose defects such as bubbles and pinholes during the drying process when used as primers. This problem urgently needs to be improved. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a water-based two-component electrostatic spray varnish primer and a preparation method thereof, which solves the problems raised in the above-mentioned background technology.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A water-based two-component electrostatic spray varnish primer, comprising a component A and a component B;

[0009] The A group is composed of:

[0010] 100 parts by weight of hydroxyl-containing aqueous polyurethane dispersion

[0011] 30-60 parts by weight of hydroxyl-free aqueous polyurethane dispersion

[0012] Propylene glycol monomethyl ether acetate 6-10 parts

[0013] Conductivity regulator 0.5-2 parts by weight

[0014] 10-20 parts of deionized water;

[0015] Group B is composed of:

[0016] 20-50 parts by weight of polyisocyanate;

[0017] Propylene glycol methyl ether acetate 5-10 parts by weight.

[0018] The water-based two-component electrostatic spray varnish primer also includes 0.2-1 parts by weight of a wetting agent.

[0019] The water-based two-component electrostatic spray varnish primer also includes 0.2-1 parts by weight of a leveling agent.

[0020] The water-based two-component electrostatic spray varnish primer also includes 0.2-1 parts by weight of a defoamer.

[0021] The hydroxyl content in the hydroxyl-containing aqueous polyurethane dispersion is 4.5%-6.5%.

[0022] The hydroxyl-containing aqueous polyurethane dispersion has a solid content of 30-40 wt % and a viscosity of 1000-10000 mPa·s at 25 degrees Celsius;

[0023] The hydroxyl-free aqueous polyurethane dispersion has a solid content of 30-40 wt % and a viscosity of 20-100 mPa·s at 25 degrees Celsius.

[0024] The polyisocyanate comprises:

[0025] HDI trimer 10-30 parts by weight

[0026] Isophorone diisocyanate 5-10 parts by weight

[0027] 5-10 parts by weight of dicyclohexylmethane diisocyanate.

[0028] The present invention also relates to a method for preparing a water-based two-component electrostatic spray varnish primer, wherein the water-based two-component electrostatic spray varnish primer comprises a component A and a component B;

[0029] The A group is composed of:

[0030] 100 parts by weight of hydroxyl-containing aqueous polyurethane dispersion

[0031] 30-60 parts by weight of hydroxyl-free aqueous polyurethane dispersion

[0032] Conductivity regulator 0.5-2 parts by weight

[0033] Propylene glycol monomethyl ether acetate 6-10 parts

[0034] 10-20 parts of deionized water;

[0035] Group B is composed of:

[0036] 20-50 parts by weight of polyisocyanate;

[0037] Propylene glycol methyl ether acetate 5-10 parts by weight;

[0038] Mix components A and B evenly and package them separately to obtain a water-based two-component electrostatic spray varnish primer.

[0039] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0040] The waterborne polyurethane system used in the present invention can have a good sealing effect on the wood material, reducing defects such as bubbles and pinholes. DETAILED DESCRIPTION

[0041] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In an embodiment of the present invention, a water-based two-component electrostatic spray varnish primer comprises a component A and a component B;

[0043] The A group is composed of:

[0044] 100 parts by weight of hydroxyl-containing aqueous polyurethane dispersion

[0045] 30-60 parts by weight of hydroxyl-free aqueous polyurethane dispersion

[0046] Propylene glycol monomethyl ether acetate 6-10 parts

[0047] Conductivity regulator 0.5-2 parts by weight

[0048] 10-20 parts of deionized water;

[0049] Group B is composed of:

[0050] 20-50 parts by weight of polyisocyanate;

[0051] Propylene glycol methyl ether acetate 5-10 parts by weight.

[0052] As a preferred embodiment, the water-based two-component electrostatic spray varnish primer further comprises 0.2-1 parts by weight of a wetting agent.

[0053] As a preferred embodiment, the water-based two-component electrostatic spray varnish primer further comprises 0.2-1 parts by weight of a leveling agent.

[0054] As a preferred embodiment, the water-based two-component electrostatic spray varnish primer further comprises 0.2-1 parts by weight of a defoamer.

[0055] As a preferred embodiment, the hydroxyl content in the hydroxyl-containing aqueous polyurethane dispersion is 4.5%-6.5%.

[0056] As a preferred embodiment, the solid content of the hydroxyl-containing aqueous polyurethane dispersion is 30-40wt%, and the viscosity at 25 degrees Celsius is 1000-10000 mPa·s;

[0057] As a preferred embodiment, the hydroxyl-free aqueous polyurethane dispersion has a solid content of 30-40 wt % and a viscosity of 20-100 mPa·s at 25 degrees Celsius.

[0058] As a preferred embodiment, the polyisocyanate comprises:

[0059] 10-30 parts by weight of HDI trimer, 5-10 parts by weight of isophorone diisocyanate, and 5-10 parts by weight of dicyclohexylmethane diisocyanate.

[0060] The present invention also relates to a method for preparing a water-based two-component electrostatic spray varnish primer, which is characterized in that: the water-based two-component electrostatic spray varnish primer comprises a component A and a component B;

[0061] The A group is composed of:

[0062] 100 parts by weight of hydroxyl-containing aqueous polyurethane dispersion

[0063] 30-60 parts by weight of hydroxyl-free aqueous polyurethane dispersion

[0064] Propylene glycol monomethyl ether acetate 6-10 parts

[0065] Conductivity regulator 0.5-2 parts by weight

[0066] 10-20 parts of deionized water;

[0067] Group B is composed of:

[0068] 20-50 parts by weight of polyisocyanate;

[0069] Propylene glycol methyl ether acetate 5-10 parts by weight;

[0070] The A and B components are mixed evenly and packaged separately to obtain a water-based two-component electrostatic spray varnish primer.

[0071] In the following examples and comparative examples:

[0072] Hydroxyl-containing waterborne polyurethane dispersion:

[0073] Covestro Bayhydrol UH 2592 has a hydroxyl content of 2.1%, a solid content of 45%, and a viscosity of 500 mPa·s.

[0074] Archroma's Mowipur 1212 has a hydroxyl content of 4.7%, a solid content of 32%, and a viscosity of 4500 mPa·s.

[0075] Hydroxyl-free waterborne polyurethane dispersions:

[0076] BASF Joncryl U 4188, solid content 38%, viscosity 50mPa·s.

[0077] BASF Joncryl U 4190, solid content 36.5%, viscosity 80mPa·s. Covestro DLN, solid content 50%, viscosity 400mPa·s. Covestro Bayhydrol U 2757, solid content 45%, viscosity 800mPa·s. Conductivity regulator: Covestro Baytron P

[0078] Thickener: Rohm and Haas Acrysol RM-2020NPR

[0079] Wetting Agents 110(BYK Chemical)

[0080] Leveling agent -333 (BYK Chemical).

[0081] HDI trimer VPLS2151 (Covestro)

[0082] IPDI (isophorone diisocyanate) T 1890 (Evonik) Dicyclohexylmethane diisocyanate: Desmodur W H12MDI

[0083] Example 1

[0084] Component A

[0085] Hydroxyl-containing waterborne polyurethane dispersion Archroma Mowipur 1212 100 parts by weight

[0086] Hydroxyl-free aqueous polyurethane dispersion BASF Joncryl U 4188 30 parts by weight Hydroxyl-free aqueous polyurethane dispersion BASF Joncryl U 4190 20 parts by weight Propylene glycol monomethyl ether acetate 8 parts by weight

[0087] Deionized water 15 parts by weight;

[0088] Conductivity regulator 2 parts by weight

[0089] Thickener: Rohm and Haas Acrysol RM-2020NPR 1 part by weight Wetting agent 110 (BYK Chemical) 1 part by weight

[0090] Leveling agent -333 (BYK Chemical) 1 part by weight.

[0091] Component B

[0092] HDI trimer 30 parts by weight

[0093] Isophorone diisocyanate 10 parts by weight

[0094] 5 parts by weight of dicyclohexylmethane diisocyanate

[0095] Propylene glycol methyl ether acetate 5 parts by weight.

[0096] Example 2

[0097] Component A

[0098] Hydroxyl-containing waterborne polyurethane dispersion Archroma Mowipur 1212 100 parts by weight

[0099] Hydroxyl-free aqueous polyurethane dispersion BASF Joncryl U 4188 10 parts by weight Hydroxyl-free aqueous polyurethane dispersion BASF Joncryl U 4190 10 parts by weight Propylene glycol monomethyl ether acetate 7 parts by weight

[0100] Deionized water 18 parts by weight;

[0101] Conductivity regulator 1 part by weight

[0102] Thickener: Rohm and Haas Acrysol RM-2020NPR 0.5 parts by weight Wetting agent 110 (BYK Chemical) 0.5 parts by weight of leveling agent -333 (BYK Chemical) 0.5 parts by weight.

[0103] Component B

[0104] HDI trimer 20 parts by weight

[0105] 5 parts by weight of isophorone diisocyanate

[0106] 10 parts by weight of dicyclohexylmethane diisocyanate

[0107] Propylene glycol methyl ether acetate 6 parts by weight.

[0108] Example 3

[0109] Component A

[0110] Hydroxyl-containing waterborne polyurethane dispersion Archroma Mowipur 1212 100 parts by weight

[0111] Hydroxyl-free aqueous polyurethane dispersion BASF Joncryl U 4188 20 parts by weight

[0112] Hydroxyl-free aqueous polyurethane dispersion BASF Joncryl U 4190 20 parts by weight Propylene glycol monomethyl ether acetate 8 parts by weight

[0113] Deionized water 18 parts by weight;

[0114] Conductivity regulator 1 part by weight

[0115] Thickener: Rohm and Haas Acrysol RM-2020NPR 1 part by weight

[0116] Wetting Agents 110 (BYK Chemical) 1 part by weight

[0117] Leveling agent -333 (BYK Chemical) 1 part by weight.

[0118] Component B

[0119] HDI trimer 20 parts by weight

[0120] Isophorone diisocyanate 20 parts by weight

[0121] 5 parts by weight of dicyclohexylmethane diisocyanate

[0122] Propylene glycol methyl ether acetate 8 parts by weight.

[0123] Comparative Example 1

[0124] Same as Example 1, Archroma Mowipur 1212 was replaced by Covestro Bayhydrol UH 2592.

[0125] Comparative Example 2

[0126] Same as Example 1, BASF Joncryl U 4188 and BASF Joncryl U 4190 were not added.

[0127] Comparative Example 3

[0128] BASF Joncryl U 4188 and BASF Joncryl U 4190 replaced by Covestro DLN 50 parts by weight.

[0129] Comparative Example 4

[0130] BASF Joncryl U 4188 and BASF Joncryl U 4190 were replaced by 50 parts by weight of Covestro Bayhydrol U2757.

[0131] Use sandpaper to polish the surface of the wood board (ash, pine, bean) to remove dust, dirt and uneven parts. Use a special dust removal cloth to clean the surface of the wood board to ensure that there is no residue. Spray the primer of the embodiment of the present invention and the comparative example, with a coating amount of 60g / m 2 After spraying and leveling for 30 minutes, enter the drying room and force bake at 60-80℃ for 60 minutes.

[0132] Spraying parameters:

[0133] Electrostatic high voltage: 60-90kV, adjusted according to the characteristics of the paint and the model of the spray gun.

[0134] Flow rate pressure: 0.30-0.55MPa, to ensure uniform spraying of powder.

[0135] Atomization pressure: 0.30-0.45MPa, keep the coating thickness uniform.

[0136] Distance from spray gun mouth to workpiece: 150-300mm.

[0137] After drying, take out the board and cool it naturally to room temperature. Observe the surface state of the dried board, test the grid, and conduct high and low temperature resistance test: (80±2)℃, (95±5)%RH for 4h, cool down to -40℃ at a rate of 1℃min, keep at (-40±2)℃ for 4h, and heat up to 80℃, 95%RH at a rate of 1℃min. 12h is one cycle, 60 cycles in total, and test the adhesion (MPa) of the pull-off method after completion.

[0138] The disk bean wood was used as the experimental substrate, and the performance test results of the embodiment and the comparative example are shown in Table 1:

[0139] Table 1

[0140]

[0141] The wood of the yam is dark in color, high in density, hard in texture and stable in performance. Due to its high density and good stability, the yam wood is relatively less likely to develop pinholes or cracks caused by wood deformation during the painting process.

[0142] The ash wood was used as the experimental substrate, and the performance test results of the embodiment and the comparative example are shown in Table 2:

[0143] Table 2

[0144]

[0145] Ash wood is hard, dense, and has beautiful texture. Due to its high density, it may have strong oil absorption. If the solvent in the primer is quickly absorbed by the wood, it may cause the surface of the paint film to dry too quickly while the internal solvent is still evaporating, forming bubbles or pinholes.

[0146] Pine wood was used as the experimental substrate, and the performance test results of the embodiment and the comparative example are shown in Table 3:

[0147] Table 3

[0148] Surface state Frame Experiment High and low temperature resistance test Example 1 The surface is smooth without bubbles or pinholes Level 0 3.7MPa Example 2 The surface is smooth without bubbles or pinholes Level 0 3.6MPa Example 3 The surface is smooth without bubbles or pinholes Level 0 3.8MPa Comparative Example 1 There are a lot of bubbles and pinholes on the surface Level 1 1.9MPa Comparative Example 2 There are a lot of bubbles and pinholes on the surface Level 3 1.3MPa Comparative Example 3 There are a lot of bubbles and pinholes on the surface Level 2 1.8MPa Comparative Example 4 There are a lot of bubbles and pinholes on the surface Level 2 1.7MPa

[0149] Pine is a coniferous wood species with a soft texture, high moisture content, and easy to crack and deform. The high moisture content of pine wood may cause water to evaporate and form bubbles during the painting process. At the same time, the softness and easy cracking of pine wood may make the paint film more susceptible to wood deformation during the drying process, resulting in pinholes or cracks.

[0150] It can be seen from the above experimental data that the present invention uses Archroma Mowipur 1212 with high molecular weight and hydroxyl content from sedge wood, in combination with BASF Joncryl U4188 with low molecular weight. The combination of the two can greatly reduce the generation of bubbles and pinholes. At the same time, the formula of the present invention is particularly effective on pine and ash wood, which can greatly improve the adhesion under high and low temperatures and reduce the generation of bubbles and pinholes.

[0151] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A water-based two-component electrostatic spray varnish primer, characterized in that: The water-based two-component electrostatic spray varnish primer comprises component A and component B; The A group is composed of: 100 parts by weight of hydroxyl-containing aqueous polyurethane dispersion 30-60 parts by weight of hydroxyl-free aqueous polyurethane dispersion Propylene glycol monomethyl ether acetate 6-10 parts by weight 10-20 parts by weight of deionized water; Conductivity regulator 0.5-2 parts by weight Group B is composed of: 20-50 parts by weight of polyisocyanate; Propylene glycol methyl ether acetate 5-10 parts by weight.

2. A water-based two-component electrostatic spray varnish primer according to claim 1, characterized in that: The water-based two-component electrostatic spray varnish primer also includes 0.2-1 parts by weight of a wetting agent.

3. The water-based two-component electrostatic spray varnish primer according to claim 1, characterized in that: The water-based two-component electrostatic spray varnish primer also includes 0.2-1 parts by weight of a leveling agent.

4. The water-based two-component electrostatic spray varnish primer according to claim 1, characterized in that: The water-based two-component electrostatic spray varnish primer also includes 0.2-1 parts by weight of a defoamer.

5. The water-based two-component electrostatic spray varnish primer according to claim 1, characterized in that: The hydroxyl content in the hydroxyl-containing aqueous polyurethane dispersion is 4.5%-6.5%.

6. The water-based two-component electrostatic spray varnish primer according to claim 1, characterized in that: The solid content of the hydroxyl-containing aqueous polyurethane dispersion is 30-40 wt %, and the viscosity at 25 degrees Celsius is 1000-10000 mPa·s.

7. The water-based two-component electrostatic spray varnish primer according to claim 1, characterized in that: The hydroxyl-free aqueous polyurethane dispersion has a solid content of 30-40 wt % and a viscosity of 20-100 mPa·s at 25 degrees Celsius.

8. The water-based two-component electrostatic spray varnish primer according to claim 1, characterized in that: The polyisocyanate comprises: HDI trimer 10-30 parts by weight Isophorone diisocyanate 5-10 parts by weight 5-10 parts by weight of dicyclohexylmethane diisocyanate.

9. A method for preparing a water-based two-component electrostatic spray varnish primer, characterized in that: The water-based two-component electrostatic spray varnish primer comprises component A and component B; The A group is composed of: 100 parts by weight of hydroxyl-containing aqueous polyurethane dispersion 30-60 parts by weight of hydroxyl-free aqueous polyurethane dispersion Propylene glycol monomethyl ether acetate 6-10 parts Conductivity regulator 0.5-2 parts by weight 10-20 parts of deionized water; The B component is: 20-50 parts by weight of polyisocyanate; Propylene glycol methyl ether acetate 5-10 parts by weight; The A and B components are mixed evenly and packaged separately to obtain a water-based two-component electrostatic spray varnish primer.

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