Preparation method of low-VOC (volatile organic compound) water-based amino baking varnish for steel rings

Abstract

The invention discloses a preparation method of water-based amino baking varnish for a low-VOC steel ring. The preparation method comprises the following steps: (1) adjusting the pH value of water-based polyester resin to 8-9; (2) sequentially adding the wetting dispersant, the pigment and the deionized water under slow stirring; (3) adjusting to a high-speed stirring state, and dropwise adding a defoaming agent; (4) grinding until the fineness is below 20 microns; (5) adding water-based acrylic resin and standby color paste into the ground water-based polyester resin, and uniformly stirring; (6) adjusting to a high-speed stirring state, and dropwise adding a defoaming agent; (7) adjusting to a medium-speed stirring state, and sequentially adding a surface tension regulator, full-butyl etherified amino resin, a coalescing agent, an anti-sagging agent, an adhesion promoter, an acid catalyst and deionized water; and (8) adjusting the viscosity, filtering and packaging. The amino baking varnish prepared by the method has the advantages of excellent environmental protection performance, low dehydrated VOC content, excellent acid and alkali resistance, excellent solvent resistance and excellent moisture resistance.

Description

Technical Field

[0001] The invention relates to the technical field of industrial coatings, and in particular to the preparation of a water-based amino baking varnish for low-VOC steel rims. Background Art

[0002] The solvents of existing baking varnishes are generally oily solvents, and the volatility of oily solvents is very harmful to the human body and the environment. As an environmentally friendly product diluted with water, water-based paint has the characteristics of no organic solvents such as toluene, xylene, esters, etc. compared with traditional solvent-based paints, and is a new generation of environmentally friendly products. Because it is energy-saving and environmentally friendly, and does not cause harm and pollution to the human body and the environment, it is deeply welcomed by users. It is the future development direction of the coating industry and an alternative product to solvent-based paints.

[0003] However, the VOC content of water-based paint for steel rims is still high, and the acid and alkali resistance are poor. Therefore, it is urgent to develop an environmentally friendly, acid and alkali corrosion-resistant paint for steel rims. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, a method for preparing a low-VOC water-based amino baking varnish for steel rims is provided. The water-based amino baking varnish prepared by the method has low VOC, excellent environmental protection, and also excellent acid and alkali resistance, solvent resistance and moisture resistance.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A method for preparing a low-VOC water-based amino baking varnish for a steel rim comprises the following steps:

[0007] (1) adding 0.2-0.5 parts of pH adjuster to 25-35 parts of waterborne polyester resin and stirring evenly to adjust the pH value to 8-9;

[0008] (2) adding 0.5 to 1.5 parts by weight of a wetting and dispersing agent, 15 to 20 parts by weight of a pigment, and 10 to 15 parts by weight of deionized water to the aqueous resin in step (1) in sequence under slow stirring at 150 to 200 r / min;

[0009] (3) adjusting the stirring speed to a high-speed stirring state of 750 to 800 r / min, adding a defoamer dropwise, a total of 0.1 to 0.2 parts by weight, and maintaining stirring for 10 to 20 minutes after the addition is completed;

[0010] (4) Grinding to a fineness of less than 20 μm and set aside;

[0011] (5) adding 15 to 25 parts by weight of water-based acrylic resin to the ground water-based polyester resin, and adding the reserved color paste while stirring, and stirring evenly;

[0012] (6) adjusting the stirring speed to a high-speed stirring state of 750 to 800 r / min, adding a defoamer to the mixed resin in step (5) in a total of 0.1 to 0.2 parts by weight, and maintaining stirring for 10 to 20 minutes after the addition is completed;

[0013] (7) adjusting the stirring speed to a medium speed stirring state of 480 to 520 r / min, and sequentially adding 0.1 to 0.3 parts by weight of a surface tension regulator, 20 to 30 parts by weight of a fully butylated amino resin, 1 to 2 parts by weight of a film-forming aid, 0.5 to 1 parts by weight of an anti-sagging aid, 1 to 2 parts by weight of an adhesion promoter, 0.1 to 0.3 parts of an acid catalyst, and 10 to 20 parts by weight of deionized water;

[0014] (8) Use water-based color matching paste to match the color and adjust the viscosity; then filter through 150 mesh and package.

[0015] As a preferred technical solution, the pH regulator is dimethylethanolamine.

[0016] As a preferred technical solution, the wetting and dispersing agent is Digo 755W wetting and dispersing agent.

[0017] As a preferred technical solution, the pigment includes titanium dioxide 996 and phthalocyanine blue.

[0018] As a preferred technical solution, the defoaming agent is a polyether siloxane copolymer.

[0019] As a further preferred technical solution, the polyether siloxane copolymer is Digo 810 defoamer.

[0020] As a preferred technical solution, the surface tension regulator is an organic silicon surfactant.

[0021] As a further preferred technical solution, the organosilicon surfactant is Digo 270 defoaming agent.

[0022] As a preferred technical solution, the acid catalyst is a blocked p-toluenesulfonic acid compound.

[0023] As a further preferred technical solution, the p-toluenesulfonic acid compound is Allnex 6395.

[0024] As a preferred technical solution, the anti-sagging agent is a polyurethane thickener.

[0025] As a further preferred technical solution, the polyurethane thickener is Hemmings 299.

[0026] As a preferred technical solution, the film-forming aid is an environmentally friendly high-boiling point alcohol ether solvent.

[0027] As a further preferred technical solution, the high boiling point alcohol ether solvent includes diethylene glycol butyl ether and dipropylene glycol butyl ether.

[0028] As an improved technical solution, the adhesion promoter is epoxy phosphate.

[0029] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] The invention discloses a method for preparing a water-based amino baking varnish for a low-VOC steel ring. The raw material is a water-based resin. In order to obtain a good grinding effect, a water-based polyester resin is first added when adding materials, and the mixture is ground to less than 20 μm. Then, a water-based acrylic resin is added, and an acid catalyst is added in sequence to accelerate the reaction speed. An adhesion promoter is added to enhance adhesion. The sequence of slow speed to high speed and then medium speed stirring is adopted to ensure that the molecular chain structure of the defoamer and other additives is mixed uniformly with the system more quickly without being affected by stirring and becoming smaller. Therefore, the amino baking varnish prepared by the method of the invention has excellent environmental protection performance, and the dehydrated VOC content is less than 250 g / L. At the same time, it also has excellent acid and alkali resistance, solvent resistance and moisture resistance.

[0031] The adhesion promoter of the present invention is epoxy phosphate, which can ensure the adhesion of the paint film on the surface of carbon steel, galvanized, electrophoresis and the like. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0033] Example 1

[0034] (1) diluting the pH regulator dimethylethanolamine with deionized water at a ratio of 1:1, adding 0.3 parts of dimethylethanolamine to 27 parts of the aqueous polyester resin and stirring evenly, and adjusting the pH value to 8-9;

[0035] (2) using a dispersing mixer with a dispersion disk diameter of 40 cm, adding 0.6 parts by weight of a wetting and dispersing agent, Digo 755W, 17 parts by weight of titanium dioxide 996 and 13 parts by weight of deionized water to the aqueous resin in step (1) at a slow stirring speed of 200 r / min;

[0036] (3) adjusting the stirring speed to a high-speed stirring state of 800 r / min, adding a defoaming agent polyether siloxane copolymer dropwise, a total of 0.12 parts by weight, and maintaining stirring for 10 minutes after the addition is completed;

[0037] (4) Grinding to a fineness of less than 20 μm and set aside;

[0038] (5) adding 19 parts by weight of water-based acrylic resin to the ground water-based polyester resin, and adding the reserved color paste while stirring, and stirring evenly;

[0039] (6) adjusting the stirring speed to a high-speed stirring state of 800 r / min, adding a defoaming agent polyether siloxane copolymer to the mixed resin in step (5), a total of 0.12 parts by weight, and maintaining stirring for 10 minutes after the addition is completed;

[0040] (7) adjusting the stirring speed to a medium speed stirring state of 500 r / min, and sequentially adding 0.14 parts by weight of surface tension regulator Digo 270, 22 parts by weight of fully butyl etherified amino resin, 1.3 parts by weight of film-forming aid diethylene glycol butyl ether, 0.6 parts by weight of anti-dripping aid polyurethane thickener, 1.5 parts by weight of adhesion promoter epoxy phosphate, 0.3 parts of acid catalyst p-toluenesulfonic acid compound and 15 parts by weight of deionized water;

[0041] (8) Use water-based color matching paste to match colors and adjust the viscosity; test the viscosity and solid content, and make plates to test the appearance and color difference. After passing the test, filter through 150 mesh and then package.

[0042] The water-based amino baking varnish prepared in this embodiment is used on a steel rim. After testing, at room temperature, the paint with a thickness of 25-35 μm is resistant to 300 acetone wipes, 30 minutes of dichloromethane immersion, 45 hours of cyclohexanone immersion, 220 hours of 0.05 mol / L sulfuric acid immersion, 220 hours of 0.15 mol / L KOH immersion, and 240 days of 40°C water immersion.

[0043] According to the test method 10.4 of GB / T 23986-2009, the dehydrated VOC content of the water-based amino baking varnish prepared in this embodiment is 210 g / L.

[0044] Example 2

[0045] (1) diluting the pH regulator dimethylethanolamine with deionized water at a ratio of 1:1, adding 0.5 parts of dimethylethanolamine to 32 parts of the aqueous polyester resin and stirring evenly, and adjusting the pH value to 8-9;

[0046] (2) using a dispersing mixer with a dispersion disk having a diameter of 40 cm, and stirring at a slow speed of 180 r / min, 1.2 parts by weight of a wetting and dispersing agent, Digo 755W, 18 parts by weight of phthalocyanine blue, and 13 parts by weight of deionized water were sequentially added to the aqueous resin in step (1);

[0047] (3) The stirring speed was adjusted to a high-speed stirring state of 780 r / min, and a total of 0.17 parts by weight of Deco 810 defoamer was added dropwise. After the addition was completed, stirring was maintained for 10 minutes;

[0048] (4) Grinding to a fineness of less than 20 μm and set aside;

[0049] (5) adding 22 parts by weight of water-based acrylic resin to the ground water-based polyester resin, and adding the reserved color paste while stirring, and stirring evenly;

[0050] (6) The stirring speed was adjusted to a high-speed stirring state of 780 r / min, and a total of 0.18 parts by weight of Dego 810 defoamer was added dropwise to the mixed resin in step (5). After the addition was completed, stirring was continued for 15 minutes;

[0051] (7) adjusting the stirring speed to a medium speed stirring state of 500 r / min, and sequentially adding 0.14 parts by weight of surface tension regulator Digo 270, 26 parts by weight of fully butyl etherified amino resin, 1.6 parts by weight of film-forming aid dipropylene glycol butyl ether, 0.8 parts by weight of anti-sagging aid polyurethane thickener Hemmings 299, 1.7 parts by weight of adhesion promoter epoxy phosphate, 0.28 parts of acid catalyst p-toluenesulfonic acid compound Allxin 6395 and 18 parts by weight of deionized water;

[0052] (8) Use water-based color matching paste to match colors and adjust the viscosity; test the viscosity and solid content, and make plates to test the appearance and color difference. After passing the test, filter through 150 mesh and then package.

[0053] The water-based amino baking varnish prepared in this embodiment is used on a steel rim. After testing, at room temperature, the paint with a thickness of 25-35 μm is resistant to acetone wiping for 290 times, dichloromethane immersion time for 25 minutes, cyclohexanone immersion time for 48 hours, 0.05 mol / L sulfuric acid immersion time for 240 hours, 0.15 mol / L KOH immersion time for 240 hours, and 40°C water immersion time for 242 days.

[0054] According to the test method 10.4 of GB / T 23986-2009, the dehydrated VOC content of the water-based amino baking varnish prepared in this embodiment is 230 g / L.

[0055] Example 3

[0056] (1) diluting the pH regulator dimethylethanolamine with deionized water at a ratio of 1:1, adding 0.4 parts of dimethylethanolamine to 30 parts of the waterborne polyester resin and stirring evenly, and adjusting the pH value to 8-9;

[0057] (2) using a dispersing mixer with a dispersion disk diameter of 40 cm, adding 1.0 parts by weight of a wetting and dispersing agent, Digo 755W, 18 parts by weight of titanium dioxide 996 and 13 parts by weight of deionized water to the aqueous resin in step (1) at a slow stirring speed of 200 r / min;

[0058] (3) The stirring speed was adjusted to a high-speed stirring state of 800 r / min, and a total of 0.15 parts by weight of Deco 810 defoamer was added dropwise. After the addition was completed, stirring was maintained for 10 minutes;

[0059] (4) Grinding to a fineness of less than 20 μm and set aside;

[0060] (5) adding 20 parts by weight of water-based acrylic resin to the ground water-based polyester resin, and adding the reserved color paste while stirring, and stirring evenly;

[0061] (6) The stirring speed was adjusted to a high-speed stirring state of 800 r / min, and a total of 0.15 parts by weight of Dego 810 defoamer was added dropwise to the mixed resin in step (5). After the addition was completed, stirring was maintained for 12 minutes;

[0062] (7) adjusting the stirring speed to a medium speed stirring state of 500 r / min, and sequentially adding 0.2 parts by weight of surface tension regulator Digo 270, 25 parts by weight of fully butyl etherified amino resin, 1.5 parts by weight of film-forming aid diethylene glycol butyl ether, 0.7 parts by weight of anti-sagging aid polyurethane thickener Hemmings 299, 1.5 parts by weight of adhesion promoter epoxy phosphate, 0.22 parts of acid catalyst p-toluenesulfonic acid compound Allxin 6395 and 16 parts by weight of deionized water;

[0063] (8) Use water-based color matching paste to match colors and adjust the viscosity; test the viscosity and solid content, and make plates to test the appearance and color difference. After passing the test, filter through 150 mesh and then package.

[0064] The water-based amino baking varnish prepared in this embodiment is used on a steel rim. After testing, at room temperature, the paint with a thickness of 25-35 μm is resistant to acetone wiping for 325 times, dichloromethane immersion time for 41 minutes, cyclohexanone immersion time for 43 hours, 0.05 mol / L sulfuric acid immersion time for 245 hours, 0.15 mol / L KOH immersion time for 238 hours, and 40°C water immersion time for 249 days.

[0065] According to the test method 10.4 of GB / T 23986-2009, the dehydrated VOC content of the water-based amino baking varnish prepared in this embodiment is 202 g / L.

[0066] Comparative Example

[0067] The existing general-purpose amino baking varnish for steel rims (specifically composed of: 50 parts of oily acrylic resin, 7 parts of 303 amino resin, 10 parts of xylene, 10 parts of butyl acetate, 5 parts of cyclohexanone, and 0.3 parts of silicone oil. 0.7 parts of Deqian 983 dispersant, and 17 parts of 996 titanium dioxide) was used as a comparative example. After testing, under the same conditions and thickness as the embodiment of the present invention, the comparative example was resistant to acetone wiping only 130 times, 15 minutes of dichloromethane immersion time, 5 hours of cyclohexanone immersion time, 35 hours of 0.05 mol / L sulfuric acid immersion, 35 hours of 0.15 mol / L KOH immersion, and 168 days of 40°C water immersion.

[0068] According to the test method 10.4 of GB / T 23986-2009, the VOC content of this comparative example is 420 g / L.

[0069] In summary, the amino baking varnish prepared by the present invention has a dehydrated VOC content of less than 250g / L, which is much lower than the existing water-soluble amino baking varnish used for steel rims, and has excellent environmental protection. At the same time, it also has excellent acid and alkali resistance, solvent resistance and moisture resistance.

Claims

1. A method for preparing a low-VOC water-based amino paint for steel rims, characterized in that The following steps are involved: (1) adding 0.2-0.5 parts of pH adjuster to 25-35 parts of waterborne polyester resin and stirring evenly to adjust the pH value to 8-9; (2) adding 0.5 to 1.5 parts by weight of a wetting and dispersing agent, 15 to 20 parts by weight of a pigment, and 10 to 15 parts by weight of deionized water to the aqueous resin in step (1) in sequence under slow stirring at 150 to 200 r / min; (3) adjusting the stirring speed to a high-speed stirring state of 750 to 800 r / min, adding a defoamer dropwise, a total of 0.1 to 0.2 parts by weight, and maintaining stirring for 10 to 20 minutes after the addition is completed; (4) Grinding to a fineness of less than 20 μm and set aside; (5) adding 15 to 25 parts by weight of water-based acrylic resin to the ground water-based polyester resin, and adding the reserved color paste while stirring, and stirring evenly; (6) adjusting the stirring speed to a high-speed stirring state of 750 to 800 r / min, adding a defoamer to the mixed resin in step (5) in a total of 0.1 to 0.2 parts by weight, and maintaining stirring for 10 to 20 minutes after the addition is completed; (7) adjusting the stirring speed to a medium speed stirring state of 480 to 520 r / min, and sequentially adding 0.1 to 0.3 parts by weight of a surface tension regulator, 20 to 30 parts by weight of a fully butylated amino resin, 1 to 2 parts by weight of a film-forming aid, 0.5 to 1 parts by weight of an anti-sagging aid, 1 to 2 parts by weight of an adhesion promoter, 0.1 to 0.3 parts of an acid catalyst, and 10 to 20 parts by weight of deionized water; (8) Use water-based color matching paste to match the color and adjust the viscosity; then filter through 150 mesh and package.

2. The method for preparing a low-VOC water-based amino baking varnish for steel rims according to claim 1, characterized in that: The pH regulator is dimethylethanolamine.

3. The method for preparing a low-VOC water-based amino baking varnish for steel rims according to claim 1, characterized in that: The wetting and dispersing agent is Digo 755W wetting and dispersing agent.

4. The method for preparing a low-VOC water-based amino baking varnish for steel rims according to claim 7, characterized in that: The pigments include titanium dioxide 996 and phthalocyanine blue.

5. The method for preparing a low-VOC water-based amino baking varnish for steel rims according to claim 1, characterized in that: The defoamer is a polyether siloxane copolymer.

6. The method for preparing a low-VOC water-based amino baking varnish for steel rims according to claim 1, characterized in that: The surface tension regulator is an organic silicon surfactant.

7. The method for preparing a low-VOC water-based amino baking varnish for steel rims according to claim 1, characterized in that: The acid catalyst is a blocked p-toluenesulfonic acid compound.

8. The method for preparing a low-VOC water-based amino baking varnish for steel rims according to claim 1, characterized in that: The anti-sagging auxiliary agent is a polyurethane thickener.

9. The method for preparing a low-VOC water-based amino baking varnish for steel rims according to claim 1, characterized in that: The film-forming aid is an environmentally friendly high-boiling point alcohol ether solvent.

10. The method for preparing a low-VOC water-based amino baking varnish for steel rims according to claim 1, characterized in that: The adhesion promoter is epoxy phosphate.