High-performance flexible explosion-proof coating composition

Abstract

The invention relates to the field of surface coatings, and particularly discloses a high-performance flexible explosion-proof coating composition, which is prepared from the following raw materials in percentage by mass: 60 to 80 percent of polyurethane dispersion, 5 to 8 percent of filler, 0.8 to 2.2 percent of pH regulator, 4 to 6 percent of coalescing agent and the balance of deionized water, wherein the polyurethane dispersion contains a cyano group. According to the flexible explosion-proof coating composition provided by the invention, polyurethane is taken as a matrix, the electron cloud density is reduced by introducing a cyano group of an electron withdrawing group, and amino-terminated polyether is passivated, so that the reaction activity of an amino-terminated compound and isocyanate is reduced; the problems that the internal structure of polyurethane is not uniform and the mechanical property of a material is reduced due to the fact that isocyanate and an amino-terminated compound react too fast at the room temperature are solved, and the adhesive force between a coating and a base material can be improved by introducing cyano as a high-polarity group.

Description

Technical Field

[0001] The invention belongs to the field of surface coatings, and in particular relates to a high-performance flexible explosion-proof coating composition. Background Art

[0002] Materials are inevitably subjected to impact loads during use. The brittle characteristics of some materials can easily cause products to break, posing the risk of injury from fragments. Therefore, during material processing, explosion-proof protection is usually required to improve its own impact resistance. Applying explosion-proof coatings to materials is currently the simplest and most effective protection method. This coating is usually made of organic polymer materials and has good flexibility, which can be used to block and absorb shock waves and fragments.

[0003] For example, patent CN112980301B provides a super-strong explosion-proof and impact-resistant composite coating and its preparation method, by wet superposition of two coating materials with different isocyanate indexes, using the chemical cross-linking reaction between layers, forming a coating with good interface fusion, and then matching activated inorganic whiskers that can transmit impact energy, so that the coating has high tensile strength and tear strength as well as good low-temperature flexibility and elongation at break, but the coating needs to be sprayed alternately for more than 3 times to achieve the final effect, and the spraying process may be more cumbersome. For example, patent CN112368305B provides a coating curing composition, the raw materials contain ethylene oxide modified multifunctional monomers, perfluoropolyether and initiator, the formed coating is resistant to scratches, bending and stretching, and it can be seen from the embodiments that the reason for the bending and stretching effects of this coating is the presence of ethylene oxide, however, the adhesion between the coating provided by this invention and the substrate needs to be improved, when the adhesion is insufficient, under the action of instantaneous impact, the protective coating may be separated from the substrate.

[0004] Therefore, there is an urgent need in the market for a flexible explosion-proof coating composition with simple use process and strong adhesion. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a flexible explosion-proof coating composition with a water-based polyurethane as a matrix, in which the terminal amino polyether is passivated by introducing an electron-withdrawing cyano group, thereby reducing the reactivity of the terminal amino compound with isocyanate, solving the problem of uneven internal structure of the polyurethane and decreased mechanical properties of the material caused by the too rapid reaction of isocyanate with the terminal amino compound at room temperature, and the introduced cyano group as a high-polarity group can improve the adhesion between the coating and the substrate.

[0006] The technical solution adopted by the present invention is:

[0007] The present invention provides a high-performance flexible explosion-proof coating composition, which comprises the following raw materials, calculated by mass percentage of 100%, 60-80% of polyurethane dispersion, 5-8% of filler, 0.8-2.2% of pH regulator, 4-6% of film-forming aid, and the balance is deionized water; wherein the polyurethane dispersion contains cyano groups.

[0008] In some embodiments, the preparation of the polyurethane dispersion comprises the following steps:

[0009] S1. Stir the hydroxyl-terminated polyolefin, the passivated amino-terminated polyether and tetrahydrofuran at room temperature until dissolved, add isophorone diisocyanate, stir for 30 to 60 minutes, then heat to 40 to 80° C. and stir for 2 to 3 hours, then add dibutyltin dilaurate and continue stirring for 1 to 2 hours to obtain an isocyanate-terminated prepolymer;

[0010] S2. Add a chain extender to the prepolymer obtained in step S1 and continue stirring for 1 to 2 hours. After standing for 8 to 12 hours, obtain a polyurethane. Add deionized water and stir for 10 to 30 minutes to obtain the polyurethane dispersion.

[0011] In some embodiments, in step S1, the Mw of the hydroxyl-terminated polyolefin is 2500-3000 g / mol.

[0012] In some embodiments, in step S1, the mass ratio of the hydroxyl-terminated polyolefin to the passivated amino-terminated polyether is 1:(0.62-0.88).

[0013] In some embodiments, in step S1, the mass ratio of the hydroxyl-terminated polyolefin to isophorone diisocyanate is 1:(1.2-3.8).

[0014] In some embodiments, in step S2, the mass ratio of the chain extender to the hydroxy-terminated polyolefin in step S1 is (0.04-0.25):1.

[0015] In some embodiments, in step S2, the chain extender is any one of trimethylolpropane, pentaerythritol or polycaprolactone polyol.

[0016] Preferably, the chain extender is polycaprolactone polyol.

[0017] The flexible explosion-proof coating composition provided by the present invention is based on waterborne polyurethane, which is synthesized by reacting a prepolymer and a chain extender, wherein the prepolymer raw material comprises an isocyanate monomer, a hydroxyl-terminated polyolefin and a passivated amino-terminated polyether, and has the following advantages:

[0018] First, the hydroxy-terminated polyolefin can form a soft segment in the main chain of the polyurethane. Since the soft segment structure does not contain polar groups, it brings better flexibility and hydrolysis resistance to the polyurethane compared with the polyester type and polyether type, which not only improves the flexibility of the coating but also makes the composition without the need to add a hydrolysis resistance agent;

[0019] In the second aspect, the present invention alleviates the problem that the common polyurethane synthesized from terminal hydroxyl compounds and isocyanate is sensitive to moisture and easily causes self-foaming by adding terminal amino polyether; and by passivating the terminal amino polyether to adjust the reaction speed, the problem that the isocyanate and the terminal amino compound react too quickly at room temperature, resulting in uneven internal structure of the polyurethane and reduced mechanical properties of the material is solved; in addition, the polyether structure of the passivated terminal amino polyether interacts strongly with the olefin structure of the terminal hydroxyl polyolefin, thereby avoiding the occurrence of microphase separation phenomenon;

[0020] Thirdly, the chain extender used in the present invention has a multi-arm structure, which can extend and extend the linear polyurethane main chain to form a branched or cross-linked structure, thereby improving the explosion-proof and impact-resistant properties of the polyurethane. At the same time, through the specific selection of polycaprolactone polyols and the adaptation of their molecular chain length to the soft segment, the cross-linking effect is enhanced.

[0021] In some embodiments, in step S1, the preparation steps of the passivated amino-terminated polyether are as follows:

[0022] The amino-terminated polyether is mixed evenly with deionized water, the temperature is maintained at 5-15° C., acrylonitrile is added, the temperature is raised to 40-60° C. after the addition is complete, the temperature is raised to 70-90° C. after stirring for 4-6 hours, the temperature is further raised to 70-90° C., stirring is continued for 2-5 hours, and the passivated amino-terminated polyether is obtained by rotary evaporation.

[0023] In some embodiments, the mass ratio of the amino-terminated polyether to acrylonitrile is 1:(0.15-0.30).

[0024] The gelation speed of the amino-terminated compound and isocyanate reaction depends on the electron cloud density and steric hindrance effect of the -NH2 nucleophilic center. In the present invention, the amino-terminated polyether reacts with acrylonitrile to introduce the electron-withdrawing group cyano, which reduces the electron cloud density and thus reduces the reactivity of the amino-terminated compound and isocyanate; in addition, the cyano group, as a highly polar group, can improve the adhesion between the coating and the substrate.

[0025] In some embodiments, the pH adjuster is at least one of N,N-dimethylethanolamine, ammonia water, and potassium hydroxide.

[0026] Preferably, the pH adjuster is N,N-dimethylethanolamine.

[0027] N,N-dimethylethanolamine has a strong pH adjustment ability and can volatilize quickly at room temperature, avoiding coating defects such as pinholes and bubbles caused by too fast volatilization. In addition, N,N-dimethylethanolamine is also used as a catalyst in this system, which can promote the reaction between isocyanate and water, thereby accelerating the curing process of polyurethane.

[0028] In some embodiments, the film-forming aid is at least one of propylene glycol methyl ether acetate, dipropylene glycol dimethyl ether or propylene glycol methyl ether.

[0029] Preferably, the film-forming aid is propylene glycol methyl ether acetate.

[0030] In some embodiments, the filler is at least one of barium sulfate, fumed silica, or cellulose nanofibrils.

[0031] Preferably, the filler is cellulose nanofibrils.

[0032] Cellulose nanofibrils can improve the compressive strength and modulus of polyurethane coatings, absorb shock waves and reduce the generation of debris by enhancing flexibility.

[0033] In some embodiments, the method for using the coating composition comprises the following steps:

[0034] Before use, the polyurethane dispersion, filler, pH adjuster, film-forming aid and deionized water are mixed evenly.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The invention provides a flexible explosion-proof coating composition with waterborne polyurethane as a matrix. The polyurethane used uses terminal hydroxyl polyolefin as a soft segment, which brings high flexibility and hydrolysis resistance to the polyurethane, improves the flexibility of the coating and makes the composition unnecessary to add a hydrolysis resistance agent; and terminal amino polyether is reacted with acrylonitrile to introduce a cyano group as an electron-withdrawing group, thereby reducing the electron cloud density and the reaction activity of the terminal amino compound with isocyanate, so that the terminal amino polyether is passivated, and the problem of uneven internal structure of the polyurethane and decreased mechanical properties of the material caused by the overly fast reaction of isocyanate with the terminal amino compound at room temperature is solved, and the introduced cyano group as a high polar group can improve the adhesion between the coating and the substrate; and at the same time, a multi-arm structure chain extender is used to extend and extend the linear polyurethane main chain to form a branched or cross-linked structure, thereby improving the explosion-proof and impact resistance of the polyurethane. DETAILED DESCRIPTION

[0037] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0038] In order to facilitate those skilled in the art to implement the present invention, some of the raw materials of the embodiments and comparative examples are described as follows:

[0039] The Mw of the hydroxyl-terminated polyolefin is 2800 g / mol;

[0040] The diameter of cellulose nanofibrils is 10 ± 5 nm and the length is 300 ± 50 nm;

[0041] The amino-terminated polyether model is T403;

[0042] The particle size of fumed silica is 50±5nm.

[0043] Preparation Example 1

[0044] The preparation steps of passivated amino-terminated polyether A are as follows:

[0045] Mix 200g of amino-terminated polyether and 800g of deionized water evenly, keep the temperature at 10°C, add 44g of acrylonitrile, raise the temperature to 50°C after the addition is complete, stir for 5h, then raise the temperature to 80°C, continue stirring for 4h, take out and rotary evaporate to obtain passivated amino-terminated polyether A.

[0046] Preparation Example 2

[0047] The preparation steps of passivated amino-terminated polyether B are as follows:

[0048] The difference between this preparation example and preparation example 1 is that the amount of acrylonitrile used is 24 g.

[0049] Preparation Example 3

[0050] The preparation steps of passivated amino-terminated polyether C are as follows:

[0051] The difference between this preparation example and preparation example 1 is that the amount of acrylonitrile used is 66 g.

[0052] Preparation Example 4

[0053] The preparation steps of polyurethane dispersion A are as follows:

[0054] S1. Stir 200 g of hydroxyl-terminated polyolefin with 152 g of passivated amino-terminated polyether A and 600 g of tetrahydrofuran at room temperature until dissolved, add 392 g of isophorone diisocyanate, stir for 45 min, then heat to 60 ° C and stir for 2.5 h, then add 16 g of dibutyltin dilaurate and continue stirring for 2 h to obtain an isocyanate-terminated prepolymer;

[0055] S2. Add 28 g of polycaprolactone polyol to the prepolymer obtained in step S1 and continue stirring for 2 h. After standing for 10 h, obtain polyurethane. Add 230 g of deionized water and stir for 20 min to obtain polyurethane dispersion A.

[0056] Preparation Example 5

[0057] The preparation steps of polyurethane dispersion B are as follows:

[0058] The difference between this preparation example and preparation example 4 is that the passivated amino-terminated polyether A in step S1 is replaced by an equal amount of amino-terminated polyether.

[0059] Preparation Example 6

[0060] The preparation steps of polyurethane dispersion C are as follows:

[0061] The difference between this preparation example and preparation example 4 is that the amount of polycaprolactone polyol used in step S2 is 6 g.

[0062] Preparation Example 7

[0063] The preparation steps of polyurethane dispersion D are as follows:

[0064] The difference between this preparation example and preparation example 4 is that the amount of polycaprolactone polyol used in step S2 is 52 g.

[0065] Preparation Example 8

[0066] The preparation steps of polyurethane dispersion E are as follows:

[0067] The difference between this preparation example and preparation example 4 is that in step S1, the passivated amino-terminated polyether A is replaced by an equal amount of passivated amino-terminated polyether B.

[0068] Preparation Example 9

[0069] The preparation steps of polyurethane dispersion F are as follows:

[0070] The difference between this preparation example and preparation example 4 is that in step S1, the passivated amino-terminated polyether A is replaced by an equal amount of passivated amino-terminated polyether C.

[0071] Preparation Example 10

[0072] The preparation steps of polyurethane dispersion G are as follows:

[0073] The difference between this preparation example and preparation example 4 is that the amount of passivated amino-terminated polyether used in step S1 is 120 g.

[0074] Preparation Example 11

[0075] The preparation steps of polyurethane dispersion H are as follows:

[0076] The difference between this preparation example and preparation example 4 is that the amount of passivated amino-terminated polyether used in step S1 is 180 g.

[0077] Example 1

[0078] A high-performance flexible explosion-proof coating composition comprises the following raw materials, calculated by mass percentage: 70% polyurethane dispersion A, 7% cellulose nanofibrils, 1.6% N,N-dimethylethanolamine, 5% propylene glycol methyl ether acetate, and the balance is deionized water.

[0079] Example 2

[0080] A high-performance flexible explosion-proof coating composition comprises the following raw materials, calculated by mass percentage: 60% polyurethane dispersion A, 5% cellulose nanofibrils, 0.8% N,N-dimethylethanolamine, 4% propylene glycol methyl ether acetate, and the balance is deionized water.

[0081] Example 3

[0082] A high-performance flexible explosion-proof coating composition comprises the following raw materials, calculated by 100% by mass: 80% of polyurethane dispersion A, 8% of cellulose nanofibrils, 2.2% of N,N-dimethylethanolamine, 6% of propylene glycol methyl ether acetate, and the balance is deionized water.

[0083] Example 4

[0084] This embodiment provides a high-performance flexible explosion-proof coating composition, and the specific implementation method is the same as that of Example 1, except that the polyurethane dispersion A is replaced by the same amount of polyurethane dispersion B.

[0085] Example 5

[0086] This embodiment provides a high-performance flexible explosion-proof coating composition, and the specific implementation method is the same as that of Example 1, except that the polyurethane dispersion A is replaced by an equal amount of polyurethane dispersion C.

[0087] Example 6

[0088] This embodiment provides a high-performance flexible explosion-proof coating composition, and the specific implementation method is the same as that of Example 1, except that the polyurethane dispersion A is replaced by the same amount of polyurethane dispersion D.

[0089] Example 7

[0090] This embodiment provides a high-performance flexible explosion-proof coating composition, and the specific implementation method is the same as that of Example 1, except that the polyurethane dispersion A is replaced by the same amount of polyurethane dispersion E.

[0091] Example 8

[0092] This embodiment provides a high-performance flexible explosion-proof coating composition, and the specific implementation method is the same as that of Example 1, except that the polyurethane dispersion A is replaced by the same amount of polyurethane dispersion F.

[0093] Example 9

[0094] This embodiment provides a high-performance flexible explosion-proof coating composition, and the specific implementation method is the same as that of Example 1, except that the polyurethane dispersion A is replaced by an equal amount of polyurethane dispersion G.

[0095] Example 10

[0096] This embodiment provides a high-performance flexible explosion-proof coating composition, and the specific implementation method is the same as that of Example 1, except that the polyurethane dispersion A is replaced by the same amount of polyurethane dispersion H.

[0097] Performance Test:

[0098] The coating compositions provided in Examples 1 to 10 were mixed evenly before use and sprayed on the 3D ceramic substrate using a spray gun: the spray diameter was 1.5 mm; the spray gun pressure was 2 kg / cm 2 ; The distance between the spray gun and the object to be coated is 10 cm; After spraying, bake at 80°C for 10 minutes, then bake at 100°C for 5 minutes, and bake at 170°C for 5 minutes to obtain a 3D composite ceramic plate with a 2mm thick explosion-proof coating, which is tested as follows:

[0099] 1. Adhesion test

[0100] Use a gridding tool to cross the coating once in the vertical and horizontal directions to form a small grid of 5mm×5mm, then adhere 3M tape, peel off the tape from the 180° direction, and use the remaining ratio of the grid to reflect the adhesion of the coating. The remaining ratio of the grid is 0 when it is 66% to 100%, 1 when it is 36% to 65%, 2 when it is 16% to 35%, 3 when it is 5% to 15%, 4 when it is 0% to 1%, and 5 when there is no peeling.

[0101] 2. Explosion-proof performance test

[0102] The 3D composite ceramic plate was impacted by a cylindrical bullet at speeds of 18 m / s, 22 m / s and 26 m / s. The state of the sample after crushing was observed. If it was still a whole without fragment separation, it was recorded as OK, otherwise it was recorded as NG.

[0103] The results are shown in Table 1.

[0104] Table 1 Performance test results

[0105]

[0106]

[0107] It can be seen from the data in Table 1 that the coatings provided by Examples 1 to 3 have strong adhesion and excellent explosion-proof performance. Compared with Example 1, the polyurethane dispersion used in Example 4 did not passivate the terminal amino polyether, lacking the electron-withdrawing group cyano, which reduced the adhesion of the coating; at the same time, the explosion-proof performance was also reduced. The possible reason is that the internal structure of the polyurethane prepared by the passivated terminal amino polyether is relatively uniform, which can effectively exert the explosion-proof effect.

[0108] Compared with Example 1, the polyurethane dispersions used in Examples 5 to 6 changed the dosage ratio of polycaprolactone polyol to terminal hydroxyl polyolefin during synthesis, which reduced the explosion-proof effect of the polyurethane; the passivated terminal amino polyether used in the polyurethane dispersions in Examples 7 to 8 changed the dosage of acrylonitrile, thereby changing the content of cyano groups. The amount of cyano groups will affect the adhesion ability of the coating, and its effect on the reaction activity of terminal amino compounds with isocyanates will affect the formation of polyurethane, thereby affecting the explosion-proof ability; the polyurethane dispersions used in Examples 9 to 10 changed the dosage ratio of terminal hydroxyl polyolefin to passivated terminal amino polyether, which affected the content of the soft segment, resulting in changes in adhesion and explosion-proof effect.

[0109] The embodiments described above do not impose any form of limitation on the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A high-performance flexible explosion-proof coating composition, characterized in that: The coating composition comprises the following raw materials in terms of 100% by mass: 60-80% polyurethane dispersion, 5-8% filler, 0.8-2.2% pH regulator, 4-6% film-forming aid, and the balance is deionized water; wherein the polyurethane dispersion contains cyano groups.

2. The coating composition according to claim 1, characterized in that The preparation of the polyurethane dispersion comprises the following steps: S1. Stir the hydroxyl-terminated polyolefin, the passivated amino-terminated polyether and tetrahydrofuran at room temperature until dissolved, add isophorone diisocyanate, stir for 30 to 60 minutes, then heat to 40 to 80° C. and stir for 2 to 3 hours, then add dibutyltin dilaurate and continue stirring for 1 to 2 hours to obtain an isocyanate-terminated prepolymer; S2. Add a chain extender to the prepolymer obtained in step S1 and continue stirring for 1 to 2 hours. After standing for 8 to 12 hours, obtain a polyurethane. Add deionized water and stir for 10 to 30 minutes to obtain the polyurethane dispersion.

3. The coating composition according to claim 2, characterized in that In step S1, the mass ratio of the hydroxyl-terminated polyolefin to the passivated amino-terminated polyether is 1:(0.62-0.88).

4. The coating composition according to claim 2, characterized in that In step S2, the mass ratio of the chain extender to the hydroxy-terminated polyolefin in step S1 is (0.04-0.25):

1.

5. The coating composition according to claim 2, characterized in that In step S2, the chain extender is any one of trimethylolpropane, pentaerythritol or polycaprolactone polyol.

6. The coating composition according to claim 2, characterized in that In step S1, the preparation steps of the passivated amino-terminated polyether are as follows: The amino-terminated polyether is mixed evenly with deionized water, the temperature is maintained at 5-15° C., acrylonitrile is added, the temperature is raised to 40-60° C. after the addition is complete, the temperature is raised to 70-90° C. after stirring for 4-6 hours, the temperature is further raised to 70-90° C., stirring is continued for 2-5 hours, and the passivated amino-terminated polyether is obtained by rotary evaporation.

7. The coating composition according to claim 6, characterized in that The mass ratio of the amino-terminated polyether to acrylonitrile is 1:(0.15-0.30).

8. The coating composition according to claim 1, characterized in that The pH regulator is at least one of N,N-dimethylethanolamine, ammonia water and potassium hydroxide.

9. The coating composition according to claim 1, characterized in that The film-forming aid is at least one of propylene glycol methyl ether acetate, dipropylene glycol dimethyl ether or propylene glycol methyl ether.

10. The coating composition according to claim 1, characterized in that The filler is at least one of barium sulfate, fumed silica or cellulose nanofibrils.

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