Single-component radix asparagi polyurea dispersion liquid and polyurea car cover film water-based paint

Abstract

The invention provides a single-component radix asparagi polyurea dispersion liquid and a polyurea car cover film water-based paint, and relates to the technical field of radix asparagi polyurea emulsions. The single-component radix asparagi polyurea dispersion liquid is obtained by reacting hydrophobic resin, a hydrophilic chain extender and a polyisocyanate prepolymer and then dispersing in water; the hydrophobic resin is composed of a first resin and a second resin. The composition of the first resin with higher ester group content and the second resin with lower ester group content is adopted, so that the hydrolysis resistance of the film layer is improved under the condition of maintaining the mechanical strength of the film layer, and moderate stripping force is provided for the film layer. The single-component radix asparagi polyurea dispersion liquid disclosed by the invention is suitable for preparing a polyurea automobile coating film water-based coating.

Description

Technical Field

[0001] This invention belongs to the field of aspartic polyurea emulsion technology, and relates to a single-component aspartic polyurea dispersion and a waterborne coating for polyurea car wrap film. Background Technology

[0002] Car wrap film is a thin film used to protect the car body, effectively preventing damage to the paint from external factors while maintaining the car's gloss. Chinese patent CN118909525A discloses a polyurea-based car wrap film, comprising component A and component B. Component A includes 10-40 parts of isocyanate prepolymer, and component B contains 5-20 parts of imide resin and 0-20 parts of polyaspartic ester resin. This prior art car wrap film is an oil-based coating, and without dilution with organic solvents, its high viscosity may hinder spraying. However, dilution with organic solvents would affect environmental protection and pose safety hazards. Water-based coatings represent an important development direction in coatings and have lower viscosity, making them well-suited for spraying processes. However, no water-based sprayable car wrap film coatings based on aspartic polyurea have been reported to date.

[0003] Compared to oil-based coatings, current water-based coatings suffer from lower mechanical strength and insufficient water resistance, hindering their practical application, especially in outdoor settings. Furthermore, for water-based sprayable automotive coatings based on aspartic polyurea, the coating needs to cover the vehicle's topcoat. While the surface tension of the vehicle's topcoat is lower than that of metals or glass, its compatibility with the aspartic polyurea coating is relatively good. Aspartic polyurea-based automotive coatings require moderate peel strength. Therefore, it is necessary to adjust the mechanical strength, water resistance, and peel strength of the water-based aspartic polyurea film, especially ensuring moderate peel strength against the vehicle's topcoat. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a single-component aspartic polyurea dispersion and a water-based polyurea car wrap film coating.

[0005] The technical solution of the present invention is as follows: A one-component aspartic polyurea dispersion is obtained by reacting a hydrophobic resin, a hydrophilic chain extender, and a polyisocyanate prepolymer and then dispersing them in water. The hydrophobic resin is a combination of a first resin and a second resin in a weight ratio of 1-10:1; The first resin contains 2-3 secondary amino groups and not less than 4 aspartic acid ester structures in its structure; The second resin contains two secondary amino groups and no more than two aspartic acid ester structures. The hydrophilic chain extender contains 2-3 secondary amino groups and 1-2 polyoxyethylene chain segments.

[0006] Preferably, the structure of the first resin is shown in formula (1). (1) Wherein, X is selected from m-valent organic groups with a molecular weight not exceeding 5000 that are reactive with NCO groups at 100℃, and R1 and R2 are individually selected from C1-C8 alkyl groups, where m=2-4.

[0008] Preferably, the structure of the second resin is shown in formula (2) or (3). (2) R7NHZNHR8 (3) Among them, Y and Z are individually selected from divalent organic groups with a molecular weight not exceeding 5000 that are reactively inert to NCO groups at 100℃; R3, R4, R7 and R8 are individually selected from C1-C4 alkyl groups; and R5 and R6 are individually selected from H or C1-C4 alkyl groups.

[0010] Preferably, the structure of the hydrophilic chain extender is shown in formula (4) or (5). (4) (5) Among them, A and B are individually selected from divalent organic groups with a molecular weight not exceeding 5000 that are reactively inert to the NCO group at 100℃, R9, R 10 R 11 and R 12 At least one of them contains a polyoxyethylene segment, R 13 and R 14 At least one of them contains a polyoxyethylene segment, R 15 and R 16 The individual is selected from H or C1-C4 alkyl groups.

[0013] Preferably, the ratio of the sum of the molar numbers of the active groups that can react with NCO groups in the hydrophobic aspartic ester resin and the hydrophilic chain extender to the molar number of NCO groups in the polyisocyanate prepolymer is 1:0.7-1.3.

[0014] Preferably, the molar ratio of the hydrophobic aspartic ester resin to the hydrophilic chain extender is 5:1 to 1:5.

[0015] Preferably, the polyisocyanate prepolymer contains a cycloalkyl structure; The NCO content in the polyisocyanate prepolymer is not less than 5 wt%.

[0016] More preferably, the polyisocyanate prepolymer is obtained by reacting a cycloalkyl-containing diisocyanate monomer with polycaprolactone diol.

[0017] A waterborne polyurea car wrap film coating is prepared from the single-component aspartic polyurea dispersion described in any of the above embodiments.

[0018] Preferably, the raw material components of the polyurea car wrap film further include one or a combination of two or more of the following: defoamer, leveling agent, thickener, film-forming aid, and rheology modifier.

[0019] The beneficial effects of this invention are as follows: This invention uses hydrophobic resin, hydrophilic chain extender and polyisocyanate prepolymer as reaction raw materials to prepare polyurea polymer with high molecular weight, which can be dispersed in water to form a stable dispersion. Moreover, the second resin has fewer aspartic ester structures, which reduces the content of ester groups with poor hydrolysis resistance in the polyurea polymer and improves the hydrolysis resistance of the film. In addition, the reduction of ester groups in the side chains of the polyurea polymer can reduce the peel force of the film. The second monomer can also improve the mechanical strength of the film within a certain content range. Detailed Implementation

[0020] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0021] On the one hand, the present invention proposes a single-component aspartic polyurea dispersion, which is obtained by reacting a hydrophobic resin, a hydrophilic chain extender and a polyisocyanate prepolymer and dispersing them in water; The hydrophobic resin is a combination of a first resin and a second resin in a weight ratio of 1-10:1; The structure of the first resin contains 2-3 secondary amino groups and not less than 4 aspartic acid ester structures; The second resin contains two secondary amino groups and no more than two aspartic acid ester structures. The structure of hydrophilic chain extenders contains 2-3 secondary amino groups and 1-2 polyoxyethylene segments.

[0022] This invention improves the hydrophilicity of the aspartic polyurea polymer obtained by reacting hydrophobic resin, hydrophilic chain extender, and polyisocyanate prepolymer by introducing a hydrophilic chain extender. The aspartic polyurea polymer can be directly dispersed in water to form a stable dispersion. Addressing the problem of insufficient hydrolysis resistance in aspartic polyurea dispersions prepared in the prior art, this invention adds a second resin to the hydrophobic resin. The second resin has fewer aspartic ester structures, i.e., fewer ester groups, reducing the content of ester groups in the side chains of the polyurea polymer. This has the following effects: (1) the polyurea polymer (i.e., the film layer) has better hydrolysis resistance; (2) the reduction of side chain ester groups also reduces the plasticizing effect of the side chain ester groups; the second monomer, within a certain content range, improves the mechanical strength of the film layer; (3) the reduction of ester groups and / or the structure of the second resin reduce the adhesion of the film layer to the substrate (especially to the car body paint), resulting in moderate peel strength and facilitating peeling.

[0023] The weight ratio of the first resin and the second resin can be any value or any value between 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1, without any particular limitation. If the weight of the first resin is too low, the advantages of the aspartic polyurea coating cannot be fully utilized, resulting in insufficient mechanical strength and poor weather resistance of the film, as well as insufficient adhesion of the film.

[0024] In some embodiments, the structure of the first resin is shown in formula (1). (1) Wherein, X is selected from m-valent organic groups with a molecular weight not exceeding 5000 that are reactive with NCO groups at 100℃, and R1 and R2 are individually selected from C1-C8 alkyl groups, where m=2-4.

[0026] The first resin described above can be prepared using existing techniques, consisting of the corresponding polyamine X(NH2). m It can be obtained by Michael addition reaction with dialkyl maleate (such as diethyl maleate and dibutyl maleate) at a molar ratio of 1:m, or it can be obtained directly from the market, such as F420, F520, F220, F421, F2850, F330, F221, etc. from Feiyang Junyan Company.

[0027] In some embodiments, the structure of the second resin is shown in formula (2) or (3). (2) R7NHZNHR8 (3) Among them, Y and Z are individually selected from divalent organic groups with a molecular weight not exceeding 5000 that are reactively inert to NCO groups at 100℃; R3, R4, R7 and R8 are individually selected from C1-C4 alkyl groups; and R5 and R6 are individually selected from H or C1-C4 alkyl groups.

[0029] For the second resin shown in formula (2) above, the structure contains two aspartic acid ester structures (i.e., two ester groups), which can be obtained by Michael addition reaction of the corresponding diamine Y(NH2)2 with dialkyl maleate esters (such as dimethyl maleate and diethyl maleate) in a molar ratio of 1:1, followed by condensation reaction with aldehydes or ketones. For the second resin shown in formula (3) above, the structure does not contain ester groups, and can be N,N'-dimethyl-1,6-hexanediamine, N,N'-dimethyl-1,8-octanediamine, N,N'-dimethyldodecane-1,12-diamine, N,N'-diisobutyl-4,4'-dicyclohexylmethane, trivinyldiamine, N,N'-diethyl-1,6-diaminohexane, N,N'-di-tert-butylethylenediamine, N,N'-diethyl-1,4-butanediamine, N,N'-diethyl-1,6-hexanediamine, etc.

[0030] The second resin of the present invention with the above structure has fewer or no ester groups in the side chain, which can improve the hydrolysis resistance of the aspartic polyurea polymer. In particular, when the second resin is as shown in formula (3) above, the ester content of the aspartic polyurea polymer can be further reduced. Moreover, since the ester group can interact with some substrates (such as glass, metal, polymer), the reduction of the ester group in the side chain of the aspartic polyurea polymer can also reduce the adhesion of the film to the substrate, especially the adhesion of the car body paint, and improve the peelability of the film.

[0031] In some embodiments, the structure of the hydrophilic chain extender is shown in formula (4) or (5) below. (4) (5) Among them, A and B are individually selected from divalent organic groups with a molecular weight not exceeding 5000 that are reactively inert to the NCO group at 100℃, R9, R 10 R 11 and R 12 At least one of them contains a polyoxyethylene segment, R 13 and R 14 At least one of them contains a polyoxyethylene segment, R 15 and R 16 The individual is selected from H or C1-C4 alkyl groups.

[0034] The above-mentioned hydrophilic chain extender improves the hydrophilicity of aspartic polyurea polymer by introducing polyoxyethylene segments. The preparation method of the above-mentioned hydrophilic chain extender can be carried out according to the existing technology. Taking the structure shown in the above formula (4) as an example, it can be obtained by Michael addition reaction of maleic acid ester containing polyoxyethylene segments (containing 1 polyoxyethylene segment or 2 polyoxyethylene segments) and diamine A(NH2)2, or it can be obtained by Michael addition reaction of diethyl maleate and diamine A(NH2)2 followed by transesterification reaction with polyoxyethylene ether monomethyl ester.

[0035] In some embodiments, the ratio of the sum of the molar numbers of reactive groups that can react with NCO groups in the hydrophobic aspartic ester resin and the hydrophilic chain extender to the molar number of NCO groups in the polyisocyanate prepolymer is 1:0.7-1.3. Reactive groups that can react with NCO groups include NH, NH2, and N=C. For example, the ratio of the sum of the molar numbers of reactive groups that can react with NCO groups to the molar number of NCO groups can be any value or any value between 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, etc., without particular limitation. Further, the ratio of the sum of the molar numbers of reactive groups that can react with NCO groups to the molar number of NCO groups can be 1:0.9-1.1, resulting in a higher molecular weight aspartic polyurea polymer, which is beneficial for improving the mechanical strength of the film.

[0036] In some embodiments, the molar ratio of the hydrophobic aspartic ester resin to the hydrophilic chain extender is 5:1 to 1:5. For example, the molar ratio of the hydrophobic aspartic ester resin to the hydrophilic chain extender can be any value or any value between 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5, etc., without particular limitation. Further, the molar ratio of the hydrophobic aspartic ester resin to the hydrophilic chain extender can be 5:1 to 1:3.

[0037] In some embodiments, the polyisocyanate prepolymer contains a cycloalkyl structure; The NCO content in the polyisocyanate prepolymer is not less than 5 wt%. The polyisocyanate prepolymer contains a cycloalkyl structure, which gives the film layer high mechanical strength. For example, the NCO content in the polyisocyanate prepolymer can be any value or any value between 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, and 11 wt%, without any particular limitation.

[0038] In some embodiments, the polyisocyanate prepolymer is obtained by reacting a cycloalkyl-containing diisocyanate monomer with polycaprolactone diol. Using a cycloalkyl-containing diisocyanate monomer leverages the large volume and rigid structure of the cycloalkyl group to improve the mechanical strength of the film. The cycloalkyl-containing diisocyanate monomer can be isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), cyclohexane-1,4-diisocyanate (CHDI), methylcyclohexyl diisocyanate (HTDI), etc.

[0039] On the other hand, the present invention also proposes a waterborne coating for polyurea car wrap film, which is prepared from the single-component aspartic polyurea dispersion described in any of the above embodiments. The single-component aspartic polyurea dispersion of the present invention exhibits high mechanical strength and suitable peelability after film formation, and can be used as a waterborne coating for polyurea car wrap film preparation.

[0040] In some embodiments, the raw material components of the polyurea car wrap film further include one or a combination of two or more of the following: defoamer, leveling agent, thickener, film-forming aid, and rheology modifier. The aforementioned additives can be directly obtained from the market. For example, the defoamer can be a dimethyl silicone oil defoamer or a polyether-modified silicone oil defoamer; the leveling agent can be a polyether-modified silicone oil leveling agent; the thickener can be an associative polyurethane thickener; the film-forming aid can be ethylene glycol butyl ether (EB), diethylene glycol butyl ether (DEB), dipropylene glycol methyl ether (DPM), etc.; and the rheology modifier can be fumed silica, organobentonite, etc.

[0041] The technical solution of the present invention will be further described and illustrated below with reference to various embodiments. Unless otherwise specified, the parts mentioned in the following embodiments are parts by weight.

[0042] Example 1 Under nitrogen protection, hydrophobic resin, hydrophilic chain extender and polyisocyanate prepolymer were mixed and reacted at 60°C for 2 hours, then heated to 100°C and reacted for another 2 hours. The mixture was then cooled to 70°C and water was added under high-speed stirring to disperse the emulsion, resulting in a single-component aspartic polyurea dispersion with a concentration of 35 wt%.

[0043] The hydrophobic resin is composed of a first resin and a second resin in a weight ratio of 1:1; the first resin is F420 and the second resin is N,N'-diisobutyl-4,4'-dicyclohexylmethane. The hydrophilic chain extender was obtained by transesterification reaction of F420 and polyoxyethylene monomethyl ether in a molar ratio of 1:2.

[0044] The polyisocyanate prepolymer is an adduct of HMDI and polycaprolactone diol (Mn is 1000) with an NCO content of 9.5 wt%.

[0045] The molar ratio of hydrophobic resin to hydrophilic chain extender is 2:1.

[0046] The molar ratio of NH groups in the hydrophobic resin and the NCO groups in the polyisocyanate prepolymer is 1:0.9.

[0047] Example 2 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the weight ratio of the first resin and the second resin was adjusted from 1:1 to 5:1. The remaining steps remain unchanged.

[0048] Example 3 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the weight ratio of the first resin and the second resin is adjusted from 1:1 to 10:1. The remaining steps remain unchanged.

[0049] Comparative Example 1 The difference between this comparative example and Example 1 is that in Example 1, the second resin was replaced with an equal weight of the first resin, meaning that no second resin was added in this comparative example. All other steps remain unchanged.

[0050] Comparative Example 2 The difference between this comparative example and Example 1 is that in Example 1, the first resin was replaced with an equal weight of the second resin, meaning that the first resin was not added in this comparative example. The remaining steps remain unchanged.

[0051] Example 4 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the molar ratio of the hydrophobic resin to the hydrophilic chain extender was adjusted from 2:1 to 5:1. The remaining steps remain unchanged.

[0052] Example 5 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the molar ratio of the hydrophobic resin and the hydrophilic chain extender was adjusted from 2:1 to 1:3. The remaining steps remain unchanged.

[0053] Example 6 The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the molar ratio of the hydrophobic resin to the hydrophilic chain extender was adjusted from 2:1 to 1:5. The remaining steps remain unchanged.

[0054] Example 7 Under nitrogen protection, hydrophobic resin, hydrophilic chain extender and polyisocyanate prepolymer were mixed and reacted at 60°C for 3 hours, then heated to 100°C and reacted for another 4 hours. The mixture was then cooled to 70°C and water was added under high-speed stirring to disperse the emulsion, resulting in a single-component aspartic polyurea dispersion with a concentration of 30 wt%.

[0055] The hydrophobic resin is composed of a first resin and a second resin in a weight ratio of 6:1; the first resin is F520 and the second resin is an imide resin.

[0056] The preparation method of imino resin is as follows: at room temperature, 1 mol of diethyl maleate is added dropwise to 1 mol of 1-methyl-2,4-cyclohexanediamine, the temperature is raised to 60℃ and kept at the temperature for 12 h, then 2 mol of butanone and 50 g of cyclohexane are added, the temperature is raised to 85℃ and reacted until anhydrous substances are removed, and excess butanone and cyclohexane are removed by vacuum distillation to obtain imino resin.

[0057] The hydrophilic chain extender was obtained by transesterification reaction of F420 and polyoxyethylene monomethyl ether in a molar ratio of 1:1.5.

[0058] The polyisocyanate prepolymer is an adduct of IPDI and polycaprolactone diol (Mn is 800) with an NCO content of 6.3 wt%.

[0059] The molar ratio of hydrophobic resin to hydrophilic chain extender is 3:1.

[0060] The molar ratio of NH groups in the hydrophobic resin and the NCO groups in the polyisocyanate prepolymer is 1:1.06.

[0061] Example 8 The difference between this embodiment and Embodiment 7 is that in Embodiment 7, the imine resin was replaced with an equal weight of N,N'-dimethyl-1,6-hexanediamine. The remaining steps remain unchanged.

[0062] The single-component aspartic polyurea dispersions obtained in Examples 1-8 and Comparative Examples 1-2 were applied to a clean car body paint surface by scraping. They were placed at 25°C and 55% humidity for 48 hours to cure into a film (car wrap film) with a thickness of 100 μm. The hydrolysis resistance, tensile strength, tear strength and pull-out adhesion of the film were tested.

[0063] Performance testing Emulsion storage stability: The single-component aspartic polyurea emulsion to be tested was placed at 50℃ for 30 days, and the presence of abnormalities such as stratification, precipitation, and floating was observed.

[0064] Tensile strength test: Tested according to the method of GB / T 528-2020.

[0065] Tear strength test: Tested according to the method of GB / T 529-2008.

[0066] Peel strength test: The 180° peel test method was used, with a sample width of 25 mm, a tensile speed of 100 mm / min, and a test temperature of 23°C. For peelable coatings, a suitable peel strength is 8-20 N / 25 mm, which provides both good protection and suitable peelability.

[0067] Hydrolysis resistance: Immerse the car body paint coated with the car wrap film in a 5wt% NaOH solution for 48 hours and observe whether there are any abnormalities such as bubbling, peeling, edge lifting, or surface stickiness.

[0068] The results are shown in Table 1 below.

[0069] Table 1

[0070] Therefore, as shown in Table 1 above, the addition of a second resin to the hydrophobic resin in this invention can adjust the peel strength of the film layer within a suitable range. When all the hydrophobic resin is the first resin, the hydrolysis resistance of the film layer is poor; when all the hydrophobic resin is the second resin, the adhesion of the film layer to the vehicle body paint is poor, and the water resistance is not good.

[0071] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited to the above embodiments, which are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the patent and the description should still fall within the scope of the present invention. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A single-component aspartic polyurea dispersion, characterized in that, It is obtained by reacting hydrophobic resin, hydrophilic chain extender and polyisocyanate prepolymer and then dispersing them in water; The hydrophobic resin is a combination of a first resin and a second resin in a weight ratio of 1-10:1; The first resin contains 2-3 secondary amino groups and not less than 4 aspartic acid ester structures in its structure; The second resin contains two secondary amino groups and no more than two aspartic acid ester structures. The hydrophilic chain extender contains 2-3 secondary amino groups and 1-2 polyoxyethylene chain segments.

2. The single-component aspartic polyurea dispersion according to claim 1, characterized in that, The structure of the first resin is shown in formula (1). （1） Wherein, X is selected from m-valent organic groups with a molecular weight not exceeding 5000 that are reactive with NCO groups at 100℃, and R1 and R2 are individually selected from C1-C8 alkyl groups, where m=2-4.

3. The single-component aspartic polyurea dispersion according to claim 1, characterized in that, The structure of the second resin is shown in formula (2) or (3). （2） R7NHZNHR8 (3) Among them, Y and Z are individually selected from divalent organic groups with a molecular weight not exceeding 5000 that are reactively inert to NCO groups at 100℃; R3, R4, R7 and R8 are individually selected from C1-C4 alkyl groups; and R5 and R6 are individually selected from H or C1-C4 alkyl groups.

4. The single-component aspartic polyurea dispersion according to claim 1, characterized in that, The structure of the hydrophilic chain extender is shown in formula (4) or (5) below. （4） （5） Among them, A and B are individually selected from divalent organic groups with a molecular weight not exceeding 5000 that are reactively inert to the NCO group at 100℃, R9, R 10 R 11 and R 12 At least one of them contains a polyoxyethylene segment, R 13 and R 14 At least one of them contains a polyoxyethylene segment, R 15 and R 16 The individual is selected from H or C1-C4 alkyl groups.

5. The single-component aspartic polyurea dispersion according to claim 1, characterized in that, The ratio of the sum of the molar numbers of the active groups that can react with NCO groups in the hydrophobic aspartic ester resin and the hydrophilic chain extender to the molar number of NCO groups in the polyisocyanate prepolymer is 1:0.7-1.

3.

6. The single-component aspartic polyurea dispersion according to claim 1, characterized in that, The molar ratio of the hydrophobic aspartic ester resin to the hydrophilic chain extender is 5:1 to 1:

5.

7. The single-component aspartic polyurea dispersion according to claim 1, characterized in that, The polyisocyanate prepolymer contains a cycloalkyl structure; The NCO content in the polyisocyanate prepolymer is not less than 5 wt%.

8. The single-component aspartic polyurea dispersion according to claim 7, characterized in that, The polyisocyanate prepolymer is obtained by reacting a cycloalkyl-containing diisocyanate monomer with polycaprolactone diol.

9. A water-based polyurea car wrap coating, characterized in that, It is prepared from the single-component aspartic polyurea dispersion according to any one of claims 1-8.

10. The polyurea car wrap waterborne coating according to claim 9, characterized in that, The raw material components of the polyurea car wrap film also include one or a combination of two or more of the following: defoamer, leveling agent, thickener, film-forming aid, and rheology modifier.

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