Preparation method and application of modified HDI (hexamethylene diisocyanate) tripolymer curing agent

Abstract

The invention discloses a preparation method and application of a modified HDI (hexamethylene diisocyanate) tripolymer curing agent, and the method comprises the following steps: mixing an HDI tripolymer with CAB (cellulose acetate butyrate) to react to obtain a prepolymer, and physically mixing the prepolymer with an HDI dipolymer to generate the modified HDI tripolymer curing agent. When the modified HDI tripolymer curing agent is used for a double-component polyurethane coating containing a metal effect pigment, compared with a common HDI tripolymer curing agent, cellulose acetate butyrate (CAB) is introduced into an HDI tripolymer and then physically mixed with an HDI dipolymer to reduce viscosity, a microgel structure in the modified HDI tripolymer is utilized, good aluminum powder orientation and solvent release performance is provided, orientation of the aluminum powder is improved, and the viscosity of the double-component polyurethane coating is improved. The gloss and the water resistance of a paint film are improved, and meanwhile, the anti-sagging performance of the coating is also obviously improved. The preparation method is especially suitable for a double-component polyurethane coating containing a metal effect pigment.

Description

Technical Field

[0001] The invention belongs to the field of polymer chemistry, and specifically relates to a preparation method and application of a modified HDI trimer curing agent. Background Art

[0002] At present, metallic glitter paints for automobiles usually add effect pigments, such as aluminum powder, in order to pursue a metallic glitter texture. However, the arrangement and orientation of the aluminum powder are usually disorderly, which causes the paint film to reflect disorderly. The existing technology is to physically mix cellulose acetate in the paint formula to improve the drying of the paint and assist in the orientation of the aluminum powder. However, the physical mixing method of cellulose acetate easily makes it difficult for it to fully participate in the reaction, and has limited help in the arrangement and orientation of the aluminum powder. At the same time, the residual hydroxyl groups in cellulose acetate are difficult to participate in the overall reaction, resulting in residual hydroxyl groups, which affects the water resistance of the paint film.

[0003] CN104877082A "Preparation method of CAB grafted modified hydroxy acrylic resin for electroplating silver coating" discloses a preparation method of CAB grafted modified hydroxy acrylic resin for electroplating silver coating, and synthesizes CAB modified hydroxy acrylic resin by using solution polymerization and grafting modification techniques; CN107141416A "A CAB modified acrylic resin and its preparation method" discloses a CAB modified acrylic resin and its preparation method; the coating is composed of two components, resin and curing agent, and the above two are only modified from the perspective of resin, the actual grafting rate is limited, the directional improvement of aluminum powder is limited, and the water resistance of the coating will decrease. The curing agents used in combination are all standard ordinary types, and the problem has not yet been solved from the perspective of curing agent (isocyanate component). Therefore, the present invention solves the problems existing in the prior art by preparing a modified HDI trimer curing agent. Summary of the invention

[0004] The object of the present invention is to provide a modified HDI trimer curing agent. When the modified HDI trimer curing agent is used for a two-component polyurethane coating containing a metal effect pigment, compared with a common HDI trimer curing agent, cellulose acetate butyrate (CAB) is introduced into the HDI trimer and then physically mixed with the HDI dimer to reduce the viscosity, and the microgel structure in the modified HDI trimer is utilized to provide good aluminum powder orientation and solvent release, thereby improving the aluminum powder orientation, the gloss and the water resistance of the paint film, and the anti-sagging performance of the coating is also significantly improved.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] In one aspect, 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 obtain a prepolymer, and then the HDI dimer is physically mixed to generate a modified HDI trimer curing agent.

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

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

[0010] The brand of the cellulose acetate butyrate CAB is 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 HD I trimer is 0.1-5:100, preferably 0.2-2:100.

[0012] The reaction conditions are 60-90° C. for 1-3 h, preferably 65-85° C. for 1-2.5 h.

[0013] In 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] On the other hand, the present invention also provides a modified HDI trimer curing agent prepared by the above method.

[0015] Finally, the present invention provides the use of the modified HDI trimer curing agent in a polyurethane coating, wherein the polyurethane coating comprises, in parts by mass:

[0016] Hydroxypropylene resin, 30-60 parts, wherein the hydroxyl content of the hydroxypropylene resin is between 1.0-2.0%, such as AC1100B;

[0017] Leveling agent, 0.1-1 part, preferably acrylate or polyester modified silicone, such as 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 positive effects of the present invention are:

[0022] (1) HDI trimer is modified by using cellulose acetate butyrate and introduced into the HDI trimer curing agent structure. The good solvent release property of cellulose acetate butyrate is utilized and then HDI dimer is physically mixed to reduce the viscosity of the system. As a result, the modified curing agent has a very good aluminum powder orientation effect when used in a two-component polyurethane coating containing metal effect pigments, thereby improving the gloss and obtaining good water resistance.

[0023] (2) By introducing cellulose acetate butyrate segments into the curing agent, the microgel structure formed in the system significantly improves the anti-sagging performance of the coating. DETAILED DESCRIPTION

[0024] The present invention is further described below by way of examples. It should be understood that the following examples are only for illustrative purposes and do not constitute any limitation to the scope of the present invention.

[0025] In the present application, % is by mass unless otherwise specified.

[0026] raw material Specification source CAB 551-0.01 Industrial Products Eastman Chemical CAB 551-0.1 Industrial Products Eastman Chemical n-Butyl acetate Analytical grade Aladdin AC1100B Industrial Products Tongde Chemical Aluminum paste Industrial Products Germany Eka Leveling agent, BYK-306 Analytical grade BYK HDI trimer HT-100 Industrial Products Wanhua Chemical HDI trimer HT-600 Industrial Products Wanhua Chemical HDI Dimer HT-400 Industrial Products Wanhua Chemical

[0027] Example 1

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

[0029] Add 100g HDI trimer (Wanhua HT-100) and 0.1g CAB 551-0.01 into the reactor, mix well, heat to 60°C and react for 1h. When the NCO value in the system reaches about 21wt%, stop the reaction to obtain prepolymer a, then add 1g HDI dimer HT-400, stir well to obtain modified HDI trimer curing agent A, and put it into a sealed container for standby use.

[0030] Example 2

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

[0032] 100g HDI trimer (Wanhua HT-600) and 1g CAB 551-0.01 were added to the reactor, mixed evenly, and heated to 65°C for 2h. When the NCO value in the system reached about 20wt%, the reaction was stopped to obtain prepolymer b, and then 7g HDI dimer HT-400 was added, and the modified HDI trimer curing agent B was obtained after stirring evenly, and placed in a sealed container for standby use.

[0033] Example 3

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

[0035] 100g HDI trimer (Wanhua HT-600) and 1.5g CAB 551-0.1 were added to the reactor, mixed evenly, and heated to 70°C for 3h. When the NCO value in the system reached about 20.5wt%, the reaction was stopped to obtain prepolymer C, and then 6g HDI dimer HT-400 was added. After stirring evenly, the modified HDI trimer curing agent C was obtained and placed in a sealed container for standby use.

[0036] Example 4

[0037] Preparation of modified HDI trimer curing agent D.

[0038] 100g HDI trimer (Wanhua HT-600) and 2g CAB 551-0.1 were added to the reactor, mixed evenly, and heated to 75°C for 2.5h. When the NCO value in the system reached about 20.5wt%, the reaction was stopped to obtain prepolymer d, and then 10g HDI dimer HT-400 was added, and the modified HDI trimer curing agent D was obtained after stirring evenly, and placed in a sealed container for standby use.

[0039] Example 5

[0040] Preparation of modified HDI trimer curing agent E.

[0041] 100g HDI trimer (Wanhua HT-100) and 1.6g CAB 551-0.01 were added to the reactor, mixed evenly, and heated to 85°C for 3h. When the NCO value in the system reached about 21.5wt%, the reaction was stopped to obtain prepolymer e, and then 10g HDI dimer HT-400 was added, and the modified HDI trimer curing agent E was obtained after stirring evenly, and placed in a sealed container for standby use.

[0042] Example 6

[0043] Preparation of modified HDI trimer curing agent F.

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

[0045] Comparative Example 1

[0046] Preparation of modified HDI trimer curing agent G.

[0047] 100g HDI trimer (Wanhua HT-600), 2g CAB 551-0.01, and 10g HDI dimer HT-400 were added to a stirring tank and physically mixed to obtain a modified HDI trimer curing agent G, which was placed in a sealed container for standby use.

[0048] Comparative Example 2

[0049] Preparation of modified HDI trimer curing agent H.

[0050] 100 g of HDI trimer (Wanhua HT-600) and 8 g of HDI dimer HT-400 were added into a stirring kettle and physically mixed to obtain a modified HDI trimer curing agent G, which was then placed into a sealed container for later use.

[0051] The preparation example is as follows:

[0052] The modified HDI trimer curing agent prepared in the above example and the unmodified HDI curing agent HT-100 are used to prepare the coating formula as follows:

[0053] Table 2

[0054]

[0055]

[0056] The coating preparation method is as follows:

[0057] ①According to the formula in Table 2, weigh the selected mass of AC1100B, aluminum paste, BYK-306, and n-butyl acetate and add them into a beaker. Stir at a speed of 500r / min for 10 minutes, then take a sample for scraper test.

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

[0059] ② According to the formula in Table 2, weigh the selected mass of HT-100 and modified HDI trimer curing agent and stir to form a uniform solution to 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 300r / min, increase the stirring rate to 500r / min, stir for 10 minutes, test, spray on the metal substrate, and perform application performance test as follows.

[0061] Gloss test: Gloss test according to GB / T 9754-2007; Equipment brand: BGD, Model: BGD 274

[0062] Anti-sagging test: Test the anti-sagging property of coatings according to GB / T 9264-2012 "Evaluation of Anti-sagging Property of Paints and Varnishes";

[0063] Water resistance test: Water resistance is tested according to GB / T 5209-85 "Determination of water resistance of paints and varnishes - Immersion method";

[0064] Pencil hardness test: Test pencil hardness according to GB / T 6739-1996 "Coating hardness pencil test method";

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

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

[0067]

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

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

[0070] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing a modified HDI trimer curing agent, comprising the following steps: The HDI trimer is mixed with cellulose acetate butyrate CAB to obtain a prepolymer, and then the HDI dimer is physically mixed to generate a modified HDI trimer curing agent.

2. The preparation method according to claim 1, characterized in that The HDI trimer is prepared by trimerization reaction of hexamethylene diisocyanate, and contains 10-80wt% of HDI trimer and other polymers, preferably the HDI trimer is HT-100 or HT-600; and / or the mass content of NCO functional groups in the HDI trimer is 20-24%.

3. The preparation method according to claim 1 or 2, characterized in that: The brand of the cellulose acetate butyrate CAB is one of CAB-551-0.01 and CAB-551-0.1 or a mixture of the two.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The mass ratio of the cellulose acetate butyrate CAB to the HDI trimer is 0.1-5:100, preferably 0.2-2:

100.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The reaction conditions are 60-90° C. for 1-3 h, preferably 65-85° C. for 1-2.5 h.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The mass ratio of the prepolymer to the HDI dimer is 100:1-10, preferably 100:5-10.

7. The modified HDI trimer curing agent prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the modified HDI trimer curing agent prepared by the preparation method according to any one of claims 1 to 6 or the modified HDI trimer curing agent according to claim 7 in a polyurethane coating, wherein the polyurethane coating comprises, in parts by mass: Hydroxypropylene 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.

Images