Preparation method of modified HDI trimer curing agent and application thereof

Abstract

The application discloses a preparation method of modified HDI trimer curing agent and application thereof, and comprises the following steps: mixing HDI trimer with cellulose acetate butyrate CAB to obtain a prepolymer, and then physically mixing HDI dimer to generate the modified HDI trimer curing agent. When the modified HDI trimer curing agent is used in two-component polyurethane paint containing metal effect pigments, compared with common HDI trimer curing agent, the viscosity is reduced by introducing cellulose acetate butyrate (CAB) into the HDI trimer and then physically mixing the HDI dimer, the good aluminum powder orientation and solvent release are provided by using the microgel structure in the modified HDI trimer, the aluminum powder orientation is improved, the gloss and the water resistance of the paint film are improved, and the anti-sagging performance of the paint is obviously improved. The modified HDI trimer curing agent is especially suitable for two-component polyurethane paint containing metal effect pigments.

Description

Technical Field

[0001] This invention belongs to the field of polymer chemistry, specifically relating to a method for preparing a modified HDI trimer curing agent and its application. Background Technology

[0002] Currently, metallic paints used in automobiles typically add effect pigments, such as aluminum powder, to achieve a metallic sheen. However, the arrangement and orientation of aluminum powder are often disordered, resulting in chaotic reflectivity in the paint film. Existing technology involves physically mixing cellulose acetate ester into the paint formulation to improve the paint's drying properties and assist in the orientation of aluminum powder. However, physically mixing cellulose acetate ester makes it difficult for it to fully participate in the reaction, offering limited help in the orientation of the aluminum powder. Furthermore, the residual hydroxyl groups in cellulose acetate ester are difficult to participate in the overall reaction, leading to hydroxyl residue and affecting the water resistance of the paint film.

[0003] CN104877082A, "Preparation Method of CAB Graft-Modified Hydroxy Acrylic Resin for Electroplating Silver Coating," discloses a method for preparing CAB graft-modified hydroxy acrylic resin for electroplating silver coating, synthesizing CAB-modified hydroxy acrylic resin using solution polymerization and graft modification techniques. CN107141416A, "A CAB-Modified Acrylic Resin and Its Preparation Method," discloses a CAB-modified acrylic resin and its preparation method. Coatings consist of two components: resin and curing agent. Both of these methods modify the resin only, resulting in limited actual grafting rates and limited improvement in the orientation of aluminum powder. Furthermore, the water resistance of the coating may decrease. The curing agents used are standard and common types, and currently, no solution has been found that addresses the problem from the perspective of the curing agent (isocyanate component). Therefore, this invention addresses the problems of the prior art by preparing a modified HDI trimer curing agent. Summary of the Invention

[0004] The purpose of this invention is to provide a modified HDI trimer curing agent. When used in two-component polyurethane coatings containing metallic effect pigments, compared with ordinary HDI trimer curing agents, the modified HDI trimer incorporates cellulose acetate butyrate (CAB) into the HDI trimer and then physically mixes the HDI dimer to reduce viscosity. Utilizing the microgel structure in the modified HDI trimer, it provides excellent aluminum powder orientation and solvent release, improves aluminum powder orientation, enhances gloss and water resistance of the coating film, and significantly improves the anti-sagging properties of the coating.

[0005] To solve the above technical problems, the present invention provides the following technical solution:

[0006] On one hand, the present invention provides a method for preparing a modified HDI trimer curing agent, comprising the following steps:

[0007] The HDI trimer is mixed with cellulose acetate butyrate CAB to form a prepolymer, and then the HDI dimer is physically mixed to form the modified HDI trimer curing agent.

[0008] The HDI trimer is prepared from hexamethylene diisocyanate through trimerization reaction, and contains 10-80wt% of HDI trimer and other polymers, preferably the HDI trimer is HT-100, HT-600, etc.

[0009] The mass content of NCO functional groups of the HDI trimer is 20-24%.

[0010] The cellulose acetate butyrate CAB has a grade of one of CAB-551-0.01 and CAB-551-0.1 or a mixture of the two.

[0011] The mass ratio of the cellulose acetate butyrate CAB to the HDI trimer is 0.1-5:100, preferably 0.2-2:100.

[0012] The reaction condition is 60-90℃ for 1-3h, preferably 65-85℃ for 1-2.5h.

[0013] The preparation method of the modified HDI trimer curing agent, the mass ratio of the prepolymer to the HDI dimer is 100:1-10, preferably 100:5-10.

[0014] In another aspect, the application also provides the modified HDI trimer curing agent prepared by the above method.

[0015] Finally, the application provides the application of the modified HDI trimer curing agent in polyurethane coating, and the polyurethane coating contains, according to mass parts:

[0016] Hydroxypropyl resin, 30-60 parts, the hydroxyl content of the hydroxypropyl resin is between 1.0-2.0%, for example, AC1100B;

[0017] Leveling agent, 0.1-1 part, preferably acrylate or polyester modified silicone, for example, BYK-306;

[0018] Aluminum silver paste, 1-10 parts;

[0019] Solvent, 20-40 parts, preferably n-butyl acetate;

[0020] Modified HDI trimer curing agent, 10-30 parts.

[0021] Compared with the prior art, the application has the following positive effects:

[0022] (1) By using cellulose acetate butyrate to modify HDI trimer, it is introduced into the structure of HDI trimer curing agent, using the good solvent release of cellulose acetate butyrate, and then physically mixing HDI dimer to reduce the viscosity of the system, so that the modified curing agent has very good aluminum powder directional effect in the two-component polyurethane coating containing metal effect pigment, improves the gloss and obtains good water resistance.

[0023] (2) The cellulose acetate butyrate segment is introduced into the curing agent, and the microgel structure formed by the system improves the anti-sagging performance of the coating. DETAILED DESCRIPTION

[0024] The application will be further illustrated by the following examples, it should be understood that the following examples are for illustrative purposes only and do not constitute any limitation on the scope of the application.

[0025] In this application, % by mass, unless otherwise specified.

[0026] Raw material Specification Source CAB 551-0.01 Commercial product Eastman Chemical CAB 551-0.1 Commercial product Eastman Chemical n-Butyl acetate Analytical pure Aldrich AC1100B Commercial product Tongde Chemical Aluminum paste Commercial product Eckart, Germany Leveling agent, BYK-306 Analytical pure BYK-Chemie HDI trimer HT-100 Commercial product Wanhua Chemical HDI trimer HT-600 Commercial product Wanhua Chemical HDI dimer HT-400 Commercial product Wanhua Chemical

[0027] Example 1

[0028] Preparation of modified HDI trimer curing agent A.

[0029] 100g HDI trimer (Wanhua HT-100), 0.1g CAB 551-0.01 were added into the reaction kettle, mixed uniformly, heated to 60℃ for 1h, when the NCO value in the system reached about 21wt%, the reaction was stopped, and the prepolymer a was obtained. Then 1g HDI dimer HT-400 was added, stirred uniformly to obtain modified HDI trimer curing agent A, which was placed in a sealed container for later use.

[0030] Example 2

[0031] Preparation of modified HDI trimer curing agent B.

[0032] 100g HDI trimer (Wanhua HT-600), 1g CAB 551-0.01 were added into the reaction kettle, mixed uniformly, heated to 65℃ for 2h. When the NCO value in the system reached about 20wt%, the reaction was stopped, and the prepolymer b was obtained. Then 7g HDI dimer HT-400 was added, stirred uniformly to obtain modified HDI trimer curing agent B, which was placed in a sealed container for later use.

[0033] Example 3

[0034] Preparation of modified HDI trimer curing agent C.

[0035] Into a reaction kettle, 100 g of HDI trimer (Wanhua HT-600) and 1.5 g of CAB 551-0.1 were added, mixed uniformly, heated to 70°C and reacted for 3 h. When the NCO value in the system reached about 20.5 wt%, the reaction was stopped to obtain a prepolymer c. Then 6 g of HDI dimer HT-400 was added, stirred uniformly to obtain a modified HDI trimer curing agent C, which was placed in a sealed container for later use.

[0036] Example 4

[0037] A modified HDI trimer curing agent D was prepared.

[0038] Into a reaction kettle, 100 g of HDI trimer (Wanhua HT-600) and 2 g of CAB 551-0.1 were added, mixed uniformly, heated to 75°C and reacted for 2.5 h. When the NCO value in the system reached about 20.5 wt%, the reaction was stopped to obtain a prepolymer d. Then 10 g of HDI dimer HT-400 was added, stirred uniformly to obtain a modified HDI trimer curing agent D, which was placed in a sealed container for later use.

[0039] Example 5

[0040] A modified HDI trimer curing agent E was prepared.

[0041] Into a reaction kettle, 100 g of HDI trimer (Wanhua HT-100) and 1.6 g of CAB 551-0.01 were added, mixed uniformly, heated to 85°C and reacted for 3 h. When the NCO value in the system reached about 21.5 wt%, the reaction was stopped to obtain a prepolymer e. Then 10 g of HDI dimer HT-400 was added, stirred uniformly to obtain a modified HDI trimer curing agent E, which was placed in a sealed container for later use.

[0042] Example 6

[0043] A modified HDI trimer curing agent F was prepared.

[0044] Into a reaction kettle, 100 g of HDI trimer (Wanhua HT-100) and 1.8 g of CAB 551-0.01 were added, mixed uniformly, heated to 90°C and reacted for 2 h. When the NCO value in the system reached about 19.5 wt%, the reaction was stopped to obtain a prepolymer f. Then 8 g of HDI dimer HT-400 was added, stirred uniformly to obtain a modified HDI trimer curing agent F, which was placed in a sealed container for later use.

[0045] Comparative Example 1

[0046] A modified HDI trimer curing agent G was prepared.

[0047] Take 100 g of HDI trimer (Wanhua HT-600), 2 g of CAB 551-0.01, and 10 g of HDI dimer HT-400 into a stirred tank, physically mix them uniformly, and obtain modified HDI trimer curing agent G, which is placed in a sealed container for later use.

[0048] Comparative Example 2

[0049] Prepare modified HDI trimer curing agent H.

[0050] Take 100 g of HDI trimer (Wanhua HT-600) and 8 g of HDI dimer HT-400 into a stirred tank, physically mix them uniformly, and obtain modified HDI trimer curing agent G, which is placed in a sealed container for later use.

[0051] Prepare, for example, as follows:

[0052] Take the modified HDI trimer curing agent prepared in the above examples and the unmodified HDI curing agent HT-100 to prepare the following formula of the coating:

[0053] Table 2

[0054]

[0055]

[0056] The preparation method of the coating is as follows:

[0057] ① According to the formula in Table 2, weigh the selected mass of AC1100B, aluminum silver paste, BYK-306, and n-butyl acetate into a beaker, stir at a speed of 500 r / min for 10 min, and then test with a sampling scraper,

[0058] Observe whether the coating film surface is uniform and has no obvious defects, stop stirring, and obtain the coating component;

[0059] ② According to the formula in Table 2, weigh the selected mass of HT-100 and modified HDI trimer curing agent to form a uniform solution, and obtain the curing agent component.

[0060] ③ Slowly add the selected mass of the coating component to the selected mass of the curing agent component at a stirring speed of 300 r / min, increase the stirring speed to 500 r / min, stir for 10 min, and then test, spray on a metal substrate, and test the application performance according to the following method.

[0061] Gloss test: test the gloss according to GB / T 9754-2007; equipment brand: Bujida, model: BGD 274

[0062] Anti-sag test: test the anti-sag property of the coating according to GB / T 9264-2012 "Evaluation of sag resistance of pigments and varnishes";

[0063] Water resistance test: test the water resistance according to GB / T 5209-85 "Determination of water resistance of pigments and varnishes by immersion method";

[0064] Pencil hardness test: test the pencil hardness according to GB / T 6739-1996 "Pencil hardness test method for coating film";

[0065] The specific test results are shown in Table 8:

[0066] Table 3 Performance test results of the prepared coatings

[0067]

[0068] As can be seen from Table 3, compared with the comparative formulations 1 and 2 using conventional curing agents, the coatings prepared in Examples 1-6 have very good gloss and water resistance, and the anti-sag property of the paint film is also greatly improved.

[0069] The above shows that the modified HDI trimer curing agent prepared by the present application, and the polyurethane coating containing metal effect pigments prepared therefrom has good aluminum powder orientation, excellent gloss and good water resistance of the paint film, and the anti-sag property of the coating is also significantly improved.

[0070] Obviously, the above examples are only examples for clearly illustrating, but not limitation to the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for preparing a modified HDI trimer curing agent, comprising the steps of: mixing HDI trimer with cellulose acetate butyrate CAB to obtain a prepolymer, and then physically mixing HDI dimer to obtain a modified HDI trimer curing agent, wherein the mass ratio of the cellulose acetate butyrate CAB to the HDI trimer is 0.1-5:100, and the mass ratio of the prepolymer to the HDI dimer is 100:1-10.

2. The production method according to claim 1, wherein The HDI trimer is selected from HT-100 and HT-600; and / or the mass content of NCO functional groups of the HDI trimer is 20-24%.

3. The production method according to claim 1, wherein The cellulose acetate butyrate CAB is one of CAB-551-0.01 and CAB-551-0.1 or a mixture thereof.

4. The production method according to any one of claims 1 to 3, wherein The mass ratio of the cellulose acetate butyrate CAB to the HDI trimer is 0.2-2:

100.

5. The production method according to any one of claims 1 to 3, wherein The reaction condition is 60-90℃ for 1-3h.

6. The production method according to any one of claims 1 to 3, wherein The reaction condition is 65-85℃ for 1-2.5h.

7. The production method according to any one of claims 1 to 3, wherein The mass ratio of the prepolymer to the HDI dimer is 100:5-10.

8. The modified HDI trimer curing agent prepared by the method of any one of claims 1-7.

9. The use of the modified HDI trimer curing agent prepared by the method of any one of claims 1-7 or the modified HDI trimer curing agent of claim 8 in polyurethane coatings, wherein the polyurethane coatings comprise, by mass fraction: hydroxypropyl resin, 30-60 parts; leveling agent, 0.1-1 part; aluminum silver paste, 1-10 parts; solvent, 20-40 parts; modified HDI trimer curing agent, 10-30 parts.

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