A method for preparing ultra-thin aluminum topcoat

Abstract

The invention discloses a method for preparing a topcoat for ultra-thin aluminum, and belongs to the technical field of topcoat coatings for ultra-thin aluminum. The method is characterized in that the topcoat comprises a pigment, a film-forming base material, an auxiliary agent and a solvent; the film-forming base material is composed of an amino resin and a polyester resin, and the amino resin accounts for (2.5-5):1, and the amino resin accounts for a mass ratio of the amino resin to the polyester resin in the film-forming base material; the topcoat for ultra-thin aluminum is roll-coated on the surface of the ultra-thin aluminum, and baked to dryness under a 150-200° C. environment. The method has the following beneficial effects: breaking the conventional amino resin ratio of 1:8, selecting an amino resin ratio of 3:1 to obtain a topcoat with better coating adhesion and flexibility suitable for ultra-thin aluminum, and well solving the problem of severe deformation of the substrate and falling off due to not adhering to the aluminum foil on a 0.014 mm aluminum plate of the substrate, and the final product meets national and industry standards.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-thin aluminum topcoat coatings, and more specifically relates to a method for preparing ultra-thin aluminum topcoat. Background Art

[0002] Ultra-thin aluminum in the coating industry refers to aluminum plates and aluminum foil substrates with a thickness of less than 0.1mm. The national color-coated plate industry standard thickness range is 0.2mm-2mm. The ultra-thin aluminum selected in the present invention has a minimum thickness of 0.014mm, which is about 15 times thinner than the national standard minimum value. Ultra-thin aluminum color coating is mainly used in decorative construction fields such as aluminum-plastic panels, aluminum honeycomb panels, aluminum-steel composite panels, and aluminum asphalt waterproofing coils. It has the characteristics of being recyclable, and the application of ultra-thin aluminum in decorative building materials greatly reduces the production cost of enterprises. It can reduce the production cost by dozens of times compared with conventional thick plates, which has brought a huge improvement in the cost performance of downstream products and effectively improved the competitiveness of products.

[0003] There are some problems in the existing aluminum topcoat technology that need to be improved, such as:

[0004] 1. The thickness control range is limited, the coating is too thick, uneconomical, the process is complicated, the efficiency is low, some equipment such as vacuum is required, and the use of expensive additives, nanomaterials, epoxy resins, etc. is costly.

[0005] 2. The paint adhesion is poor, and the coating's corrosion resistance, weather resistance, hardness and other properties still have room for improvement

[0006] 3. It cannot be applied to ultra-thin aluminum paint coatings. The high temperature during the drying process can easily cause the aluminum skin to fold or wrinkle.

[0007] Due to the high flexibility and ultra-thin thickness of the ultra-thin aluminum substrate, this substrate is very prone to thermal deformation under high temperature conditions, causing folds, wrinkles, etc. There are strict requirements on the coating's baking temperature, baking time, film thickness, adhesion, hardness and other performance parameters. Summary of the invention

[0008] In order to solve the above problems and overcome the shortcomings of the prior art, the present invention provides a method for preparing an ultra-thin aluminum topcoat, which can effectively solve the problem that due to the high flexibility and ultra-thin thickness of the ultra-thin aluminum substrate, the substrate is very likely to be thermally deformed under high temperature conditions, thereby causing folds, wrinkles, etc. There are strict requirements on the performance parameters of the coating, such as the baking temperature, baking time, film thickness, adhesion, hardness, etc.

[0009] The specific technical solution of the present invention to solve the above technical problems is an ultra-thin aluminum topcoat, characterized in that the ultra-thin aluminum topcoat comprises a pigment, a film-forming base material, an additive and a solvent; the film-forming base material is composed of an amino resin and a polyester resin, and the amino resin accounts for (2.5-5):1, and the amino resin accounts for the mass ratio of the amino resin to the polyester resin in the film-forming base material;

[0010] The weight proportions of the pigment, film-forming base material, solvent and additive are (40-60) parts: (20-40) parts: (10-12) parts: (8-10) parts;

[0011] The solvent is a mixture of xylene, ether and 100#, with a volume ratio of 3:(0.5-1.5):(0.5-1.5);

[0012] The additives include a leveling agent, a catalyst, a defoaming agent and an adhesion promoter, with the weight proportions being (10-13) parts: (3-8) parts: (3-5) parts: (18-30) parts.

[0013] The preparation method of the ultra-thin aluminum topcoat comprises: mixing xylene, ether and 100# according to the above volume ratio, adding (1 / 3-1 / 2) of the formula amount of polyester resin and mixing evenly, then adding the formula amount of dispersant and pigment and stirring again, standing for 2-10 hours and then grinding multiple times using a series sand mill, the temperature cannot be higher than 55 degrees Celsius, and the particle size is less than 2 microns;

[0014] After standing for more than 5 hours again, add amino resin and the remaining polyester resin according to the preset amino resin ratio, and the formulated amount of leveling agent, catalyst, defoamer and adhesion promoter into the mixture, disperse and mix them in a disperser, and filter the mixture through a 2500-3250 mesh filter.

[0015] The purpose of the ultra-thin aluminum topcoat is to prepare an ultra-thin aluminum coating using the ultra-thin aluminum topcoat. The specific method includes: rolling the ultra-thin aluminum topcoat onto the surface of the ultra-thin aluminum, and baking it to dryness under a temperature of 150°C-200°C.

[0016] Furthermore, the roller coating thickness is 0.009-0.1 mm; the thickness of the ultra-thin aluminum plate is 0.014-0.1 mm.

[0017] Furthermore, the pigment is a colored slurry.

[0018] Furthermore, the catalyst is ammonium dodecylbenzenesulfonate; the leveling agent is an acrylate copolymer; the defoamer is an organosilicon or polyether defoamer; and the adhesion promoter is a phosphate or silane promoter.

[0019] Furthermore, the model of the amino resin is 5703 or 5747 or a mixture of the two.

[0020] The beneficial effects of the present invention are:

[0021] Make the coating curing strip conform to the physical properties of ultra-thin aluminum, greatly reduce the problems of folding, wrinkling, thermal deformation, etc. in the production and application of ultra-thin aluminum, so that ultra-thin aluminum can be used in the field of decorative building materials, and greatly reduce the production cost of customers under the premise of meeting national standards;

[0022] The present invention adopts a topcoat for ultra-thin aluminum and a preparation method, which breaks the conventional amino resin ratio of 1:8 and selects an amino resin ratio of 3:1 to obtain a topcoat with better coating adhesion and flexibility suitable for ultra-thin aluminum, and well solves the problem of severe deformation of the base material on the 0.014mm aluminum plate of the substrate and falling off due to not adhering to the aluminum foil, and the final product meets national and industry standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attached Figure 1 This is a graph showing the relationship between the proportion of conventional amino resin and the adhesion, hardness and flexibility of the coating;

[0024] Attached Figure 2 This is a topcoat coating diagram of ultra-thin aluminum in Example 1 of the present invention;

[0025] Attached Figure 3 This is a topcoat coating diagram of ultra-thin aluminum in Example 2 of the present invention;

[0026] Attached Figure 4 This is a topcoat coating diagram of ultra-thin aluminum in Example 3 of the present invention;

[0027] Attached Figure 5 This is a topcoat coating diagram of the aluminum foil of Comparative Example 1 of the present invention;

[0028] Attached Figure 6 This is a topcoat coating diagram of the aluminum foil of Comparative Example 2 of the present invention;

[0029] Attached Figure 7 This is a topcoat coating diagram of the aluminum foil of Comparative Example 3 of the present invention;

[0030] Attached Figure 8 This is a topcoat coating diagram of the aluminum foil of Comparative Example 4 of the present invention;

[0031] Attached Fig. 9 This is a topcoat coating diagram of the aluminum foil of Comparative Example 5 of the present invention;

[0032] Attached Fig.10 This is a topcoat coating diagram of the aluminum foil of Comparative Example 6 of the present invention;

[0033] Attached Fig.11 This is a topcoat coating diagram of the aluminum foil of Comparative Example 7 of the present invention;

[0034] Attached Fig.12 This is a topcoat coating diagram of the aluminum foil of Comparative Example 8 of the present invention;

[0035] Attached Fig.13 This is a topcoat coating diagram of the aluminum foil of Comparative Example 9 of the present invention;

[0036] Attached Fig.14 is a topcoat coating diagram of the aluminum foil of Comparative Example 10 of the present invention;

[0037] Attached Fig.15 This is a topcoat coating diagram of the aluminum foil of Comparative Example 11 of the present invention; DETAILED DESCRIPTION

[0038] In the description of the present invention, specific details are only for a full understanding of the embodiments of the present invention, but those skilled in the art should know that the implementation of the present invention is not limited to these details. In addition, well-known structures and functions are not described or shown in detail to avoid blurring the key points of the embodiments of the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] Specific implementation of the present invention:

[0040] In order to better understand the present invention, a specific embodiment is used for illustration. It is worth emphasizing that the effect of this embodiment is not substantially different from the various embodiments within the protection scope of the present invention, including the respective reagents and the content ratio of the reagents, and all of them can achieve the effects described in the present invention and solve the above-mentioned problems. Other combinations are not described here.

[0041] Example 1 The topcoat for ultra-thin aluminum includes a pigment, a film-forming base material, an additive and a solvent; the pigment is a colored slurry, the film-forming base material is composed of an amino resin and a polyester resin, and the amino resin ratio is 2.5:1, and the amino resin ratio is the mass ratio of the amino resin to the polyester resin in the film-forming base material;

[0042] The model of the amino resin is 5703;

[0043] The additives include a leveling agent, a catalyst, a defoamer and an adhesion promoter, with a mass ratio of 10:7:4:30; the catalyst is ammonium dodecylbenzenesulfonate; the leveling agent is an acrylate copolymer; the defoamer is silicone; and the adhesion promoter is a phosphate ester;

[0044] The preparation method of the ultra-thin aluminum topcoat comprises: mixing xylene, ether and 100# according to the above volume ratio, adding 1 / 3 of the formula amount of polyester resin and mixing evenly, then adding the formula amount of dispersant and pigment and stirring again, standing for 2 hours and then grinding multiple times using a series sand mill, the temperature cannot be higher than 55 degrees Celsius, and the particle size is less than 2 microns;

[0045] After standing for more than 5 hours, the mixture is added with amino resin and the remaining polyester resin according to the preset amino resin ratio, and the formulated amount of leveling agent, catalyst, defoamer and adhesion promoter, and dispersed and mixed in a disperser, and the mixture is filtered through a 2500 mesh filter. The solvent is a mixture of xylene, ether and 100#, with a volume ratio of 3:0.5:0.5.

[0046] The method for preparing a coating using the ultra-thin aluminum topcoat comprises: rolling the ultra-thin aluminum topcoat onto the surface of the ultra-thin aluminum, and baking the coating to dryness under a 150° C. environment.

[0047] The mixture is rolled and coated to a thickness of 0.01 mm; the ultra-thin aluminum plate has a thickness of 0.014 mm.

[0048] Example 2 The topcoat for ultra-thin aluminum includes a pigment, a film-forming base material, an additive and a solvent; the pigment is a colored slurry, the film-forming base material is composed of an amino resin and a polyester resin, and the amino resin ratio is 3:1, and the amino resin ratio is the mass ratio of the amino resin to the polyester resin in the film-forming base material;

[0049] The amino resin is of model 5703 or 5747 or a mixture of the two; the ratio is 4:1;

[0050] The additives include a leveling agent, a catalyst, a defoamer and an adhesion promoter, with a mass ratio of 13:6:3:18; the catalyst is ammonium salt of dodecylbenzenesulfonate; the leveling agent is an acrylate copolymer; the defoamer is a polyether defoamer; and the adhesion promoter is a silane promoter;

[0051] The preparation method of the ultra-thin aluminum topcoat comprises: mixing xylene, ether and 100# according to the above volume ratio, adding 1 / 2 of the formula amount of polyester resin and mixing evenly, then adding the formula amount of dispersant and pigment and stirring again, standing for 10 hours and grinding multiple times using a series sand mill, the temperature cannot be higher than 55 degrees Celsius, and the particle size is less than 2 microns;

[0052] After standing for more than 5 hours, the mixture is added with amino resin and the remaining polyester resin according to the preset amino resin ratio, and the formulated amount of leveling agent, catalyst, defoamer and adhesion promoter, and dispersed and mixed in a disperser, and the mixture is filtered through a 3250 mesh filter. The solvent is a mixture of xylene, ether and 100#, with a volume ratio of 3:1:1.

[0053] The method for preparing a coating using the ultra-thin aluminum topcoat comprises: rolling the ultra-thin aluminum topcoat onto the surface of the ultra-thin aluminum, and baking the coating to dryness under a 160° C. environment.

[0054] The mixture is rolled and coated to a thickness of 0.02 mm; the ultra-thin aluminum plate is 0.05 mm thick.

[0055] Example 3 The topcoat for ultra-thin aluminum includes a pigment, a film-forming base material, an additive and a solvent; the pigment is a colored slurry, the film-forming base material is composed of an amino resin and a polyester resin, and the amino resin ratio is 5:1, and the amino resin ratio is the mass ratio of the amino resin to the polyester resin in the film-forming base material;

[0056] The model of the amino resin is 5747;

[0057] The additives include a leveling agent, a catalyst, a defoamer and an adhesion promoter, with a mass ratio of 10:8:5:28; the catalyst is ammonium dodecylbenzenesulfonate; the leveling agent is an acrylate copolymer; the defoamer is silicone; and the adhesion promoter is a phosphate ester;

[0058] The preparation method of the ultra-thin aluminum topcoat comprises: mixing xylene, ether and 100# according to the above volume ratio, adding 1 / 3 of the formula amount of polyester resin and mixing evenly, then adding the formula amount of dispersant and pigment and stirring again, standing for 5 hours and grinding multiple times using a series sand mill, the temperature cannot be higher than 55 degrees Celsius, and the particle size is less than 2 microns;

[0059] After standing for more than 5 hours, the mixture is added with amino resin and the remaining polyester resin according to the preset amino resin ratio, and the formulated amount of leveling agent, catalyst, defoamer and adhesion promoter, and dispersed and mixed in a disperser, and the mixture is filtered through a 2800 mesh filter. The solvent is a mixture of xylene, ether and 100#, with a volume ratio of 3:1.5:1.5.

[0060] The method for preparing a coating using the ultra-thin aluminum topcoat comprises: rolling the ultra-thin aluminum topcoat onto the surface of the ultra-thin aluminum, and baking it at 170° C. until it is dry.

[0061] The mixture is rolled and coated to a thickness of 0.1 mm; the ultra-thin aluminum plate has a thickness of 0.1 mm.

[0062] This example is tested according to GB / T 12754-2019 and YST 431-2009 aluminum and aluminum alloy color coated plates and strips UV aging test standards (weather resistance), T bend, pencil hardness, boiling water resistance (enterprise standard at least 2H), solvent resistance (enterprise standard at least 80 times), and the results are as follows:

[0063]

[0064] By the attached Figure 2-4 Judging from the appearance of the aluminum foil coating with different thicknesses of 0.014-0.1mm, there is no deformation in appearance.

[0065] From the data analysis in Table 1, it can be seen that in Examples 1-3, ultra-thin aluminum coatings were prepared for different proportions of amino resin and different ultra-thin aluminum, according to GB / T 12754-2019 and YST 431-2009 aluminum and aluminum alloy color coated plates, strip ultraviolet aging test standards (weather resistance), T bend, pencil hardness, boiling water resistance (enterprise standard at least 2H), solvent resistance (enterprise standard at least 80 times) all met the requirements of the above standards.

[0066] In order to further study the comparative effect of the proportion of amino resin and the type of amino resin products, Examples 4-7 are studied on products with different proportions of amino resin and types of amino resin. According to GB / T 12754-2019 and YST431-2009 Aluminum and aluminum alloy color coated plates, strips UV aging test standards (weather resistance), T bend, pencil hardness, boiling water resistance (enterprise standard at least 2H), solvent resistance (enterprise standard at least 80 times) are tested. The implementation process and results are as follows:

[0067] Example 4 The preparation method is the same as that of Example 2, except that: in the preparation process of this example, the ratio of amino resin is 3:1, wherein the amino resin type is 5703;

[0068] Example 5 The preparation method is the same as that of Example 2, except that: in the preparation process of this example, the amino resin accounts for 3.5:1, wherein the amino resin type is a mixture of 5703 and 5747, and the mass ratio of amino resin 5703 and 5747 is 90%:10%;

[0069] Example 6 The preparation method is the same as that of Example 2, except that: in the preparation process of this example, the amino resin accounts for 4:1, wherein the amino resin type is a mixture of 5703 and 5747, and the mass ratio of amino resin 5703 and 5747 is 80%:20%;

[0070] Example 7 The preparation method is the same as that of Example 2, except that: in the preparation process of this example, the amino resin accounts for 4.5:1, wherein the amino resin type is a mixture of 5703 and 5747, and the mass ratio of amino resin 5703 and 5747 is 20%:80%;

[0071]

[0072] From the data analysis in Table 2, we can see that:

[0073] Examples 4-7 are a study of products with different proportions of amino resins and types of amino resins within the scope of protection of the present invention. According to GB / T 12754-2019 and YST 431-2009 Aluminum and Aluminum Alloy Color Coated Plates, Strip UV Aging Test Standards (Weather Resistance), T-bend, pencil hardness, boiling water resistance (enterprise standard at least 2H), and solvent resistance (enterprise standard at least 80 times) all meet the requirements of the above standards, and there is no significant difference from Examples 1-3.

[0074] In order to more intuitively demonstrate the process advantages of the ultra-thin aluminum topcoat and preparation method of the present invention, the ultra-thin aluminum topcoat and preparation method of the present invention and the equivalent replacement method of the same process are studied.

[0075] Comparative Example 1:

[0076] By way of reference, invention patent CN201610559104, wherein fully methylated amino resin is used to prepare topcoat and applied on aluminum foil; test conditions: PMT / ℃, 216-224℃ (time 90 seconds), substrate is 0.5mm aluminum plate, dry film is 24±1um, and the amino resin accounts for 1:8;

[0077] Comparative Example 2:

[0078] The preparation method is the same as that of Comparative Example 1, except that: in the preparation process of this comparative example, the proportion of amino resin is 1:8, wherein the amino resin type is 5747;

[0079] Comparative Example 3:

[0080] The preparation method is the same as that of Comparative Example 1. In the preparation process of this comparative example, the proportion of amino resin is 1:8, but the difference is that the type of amino resin is 5703;

[0081] Comparative Example 4:

[0082] The preparation method is the same as that of Comparative Example 2. In the preparation process of this comparative example, the ratio of amino resin is 1:8, wherein the amino resin type is 5747; the difference is that the substrate is a 0.014 mm aluminum plate;

[0083] Comparative Example 5:

[0084] The preparation method is the same as that of Comparative Example 3. In the preparation process of this comparative example, the ratio of amino resin is 1:8, wherein the amino resin type is 5703; the difference is that the substrate is a 0.014 mm aluminum plate;

[0085] Comparative Example 6:

[0086] The preparation method is the same as that of Comparative Example 4, except that the reaction temperature is 160°C and the reaction time is 45s;

[0087] Comparative Example 7:

[0088] The preparation method is the same as that of Comparative Example 5, except that the reaction temperature is 160°C and the action time is 45s;

[0089] Comparative Example 8:

[0090] The preparation method is the same as that of Comparative Example 4, except that the amino resin of the present invention is used in a ratio of 3:1;

[0091] Comparative Example 9:

[0092] The preparation method is the same as that of Comparative Example 5, except that the amino resin of the present invention is used in a ratio of 3:1;

[0093] The above comparative examples 1-9 were tested according to GB / T 12754-2019 and YST 431-2009 aluminum and aluminum alloy color coated plates and strips UV aging test standards (weather resistance), T bend, pencil hardness, boiling water resistance (enterprise standard at least 2H), solvent resistance (enterprise standard at least 80 times), and the results are as follows:

[0094]

[0095] (1) By the attached Figure 5-6 From the appearance of the 0.5 mm thick aluminum foil coating, there is no deformation in appearance. Combined with Table 3, the aluminum foil coatings of Comparative Examples 1 and 2 have good effects, and have good weather resistance, water boiling resistance and solvent resistance.

[0096] According to Table 3 and Appendix Figure 7 It can be seen that the solvent resistance of Comparative Example 3 is insufficient, which may be due to the type of amino resin 5703;

[0097] In general, the aluminum foil coating effects of Comparative Examples 1 and 2 at 0.5 mm thickness are good, and the performance can meet the requirements of the standards.

[0098] (2) By the attached Figure 8-9It can be seen that the coating substrates in Comparative Examples 4 and 5 are seriously deformed, and the only difference from Comparative Examples 1 and 2 is the thickness of the aluminum foil. Therefore, the amino resin in the prior art accounts for 1:8, and there is no universality in the application of aluminum foils with a thickness of 0.5 mm and 0.014 mm.

[0099] (3) By the attached Figure 8-9 and attached Figure 10-11 It can be seen that compared with Comparative Examples 4 and 5, Comparative Examples 6 and 7 further adjusted the temperature and action time the same as those of the present invention, and the results showed that the substrate was deformed, the boiling resistance was less than 2h, and the solvent resistance was less than 80 times;

[0100] Therefore, the excellent performance of the coating of 0.014 mm ultra-thin aluminum foil cannot be obtained simply by adjusting the temperature and action time;

[0101] (4) By the attached Figure 8-9 and attached Figure 12-13 It can be seen that compared with Comparative Examples 4 and 5, Comparative Examples 8 and 9 further adjusted the ratio of the amino resin of the present invention to 3:1, and the result was that the substrate was severely deformed.

[0102] Therefore, simply adjusting the ratio of the amino resin, even if the amino resin ratio of the present invention is 3:1, the excellent performance of the coating of the ultra-thin aluminum foil cannot be obtained;

[0103] In order to more intuitively demonstrate the process advantages of the ultra-thin aluminum topcoat and preparation method of the present invention, further research was conducted on the correlation between the proportion of amino resin and adhesion performance, hardness and flexibility, and the following findings were made:

[0104] Depend on Figure 1 It can be seen that:

[0105] (1) There is a normal distribution between the amino resin ratio and the adhesion performance, that is, the higher the amino resin ratio, the stronger the adhesion performance, reaching the highest at 1: (10-15), and then with the change of the amino resin ratio, the adhesion performance will show a weakening trend; the amino resin ratio is the mass ratio of the amino resin to the polyester resin in the film-forming base material. The larger the amino resin ratio in the figure, the smaller the mass fraction of the amino resin;

[0106] (2) The proportion of amino resin is negatively correlated with hardness, that is, the greater the proportion of amino resin, the lower the hardness;

[0107] (3) The proportion of amino resin is positively correlated with flexibility, that is, the greater the proportion of amino resin, the better the flexibility;

[0108] That is to say, amino resin plays a cross-linking role in the system. Adding type 5747 and type 5703 to polyester resin in a suitable proportion will improve the adhesion and performance of the coating, but excessive addition will make the paint film brittle and fall off, and the required drying temperature is too high, which will cause the aluminum foil to fold and wrinkle. The above theory is also in line with common sense, that is, under normal circumstances, the greater the proportion of amino added, the worse the flexibility of the coating, and the paint film is too hard, which will cause the coating to fall off easily. In the range of 8 to 16 of amino resin, it has higher adhesion performance and more balanced hardness and flexibility, which is also mentioned in other invention patents such as CN201610559104 and papers.

[0109] Therefore, in order to solve the problems of serious deformation of the substrate and falling off due to failure to adhere to the aluminum foil on the 0.014 mm aluminum plate of the substrate in the above comparative example, the topcoat should be adjusted to have better coating adhesion and flexibility to solve the problems of serious deformation of the substrate and falling off due to failure to adhere to the aluminum foil;

[0110] Based on the above research, the present invention attempts to adjust the ratio of amino resin to 1: (10-15) to obtain better coating adhesion and flexibility;

[0111] Comparative Example 10:

[0112] The preparation method is the same as that of Comparative Example 6, except that the amino resin ratio is theoretically preferred at 1:12;

[0113] Comparative Example 11:

[0114] The preparation method is the same as that of Comparative Example 7, except that the amino resin ratio is theoretically preferred at 1:12;

[0115] The above comparative examples 10-11 were tested according to GB / T 12754-2019 and YST 431-2009 aluminum and aluminum alloy color coated plates and strips UV aging test standards (weather resistance), T bend, pencil hardness, boiling water resistance (enterprise standard at least 2H), solvent resistance (enterprise standard at least 80 times), and the results are as follows:

[0116]

[0117] (1) Based on the data in Table 4 and the attached Figure 14-15 Analysis shows that:

[0118] In order to solve the problems in the above comparative example, on the 0.014mm aluminum plate of the substrate, the substrate is severely deformed, and the adhesion is not on the aluminum foil, resulting in falling off; the topcoat should be adjusted to have better coating adhesion and flexibility, and the amino resin ratio is adjusted to 1: (10-15) to obtain better coating adhesion and flexibility; the results show that it seriously does not meet the national standards, specifically, the substrate is deformed, and the product's water boiling resistance and solvent resistance and other properties do not meet the national standards.

[0119] Therefore, the ultra-thin aluminum topcoat, preparation method and use thereof adopted by the present invention break the conventional amino resin ratio of 1:8 and select an amino resin ratio of 3:1 to obtain a coating with better adhesion and flexibility suitable for ultra-thin aluminum topcoat, which well solves the problem of severe deformation of the substrate on the 0.014mm aluminum plate of the substrate and falling off due to failure to adhere to the aluminum foil, and the final product meets national and industry standards.

[0120] In summary: the present invention realizes a topcoat system that can be used for ultra-thin aluminum. By adjusting the proportion of amino resin in the topcoat, the different physical properties of ultra-thin aluminum under different thickness specifications can be met, the curing conditions of the topcoat can be reduced, and the problems of easy deformation, falling off, and wrinkling of the coating when applied to the ultra-thin aluminum substrate can be solved.

Claims

1. A method for preparing an ultra-thin aluminum topcoat, characterized in that The topcoat comprises a pigment, a film-forming base material, an additive and a solvent; the film-forming base material is composed of an amino resin and a polyester resin, and the amino resin ratio is (2.5-5):1, and the amino resin ratio is the mass ratio of the amino resin to the polyester resin in the film-forming base material; the preparation method of the topcoat for ultra-thin aluminum comprises the following specific steps: (1) Mix xylene, ether and 100# in a volume ratio of 3: (0.5-1.5): (0.5-1.5) evenly, add (1 / 3-1 / 2) the formula amount of polyester resin and mix evenly, then add the formula amount of pigment and stir again. After standing for 2-10 hours, use a series sand mill to grind multiple times. The temperature cannot be higher than 55 degrees Celsius and the particle size is less than 2 microns; (2) the ground mixture of step (1) is allowed to stand for more than 5 hours, amino resin and the remainder of polyester resin are added to the ground mixture according to the preset amino resin ratio, and then the formulated amount of leveling agent, catalyst, defoamer and adhesion promoter are added, and the mixture is dispersed and mixed in a disperser, and the mixture is filtered through a 2500-3250 mesh filter to obtain an ultra-thin aluminum topcoat; The thickness of the ultra-thin aluminum plate is 0.014-0.1 mm; The weight proportions of the pigment, film-forming base material, solvent and additive are (40-60) parts, (20-40) parts, (10-12) parts and (8-10) parts; The additives include a leveling agent, a catalyst, a defoamer and an adhesion promoter, with a mass ratio of (10-13): (3-8): (3-5): (18-30); The amino resin has a model of 5703 or 5747 or a mixture of the two.

2. The method for preparing the ultra-thin aluminum topcoat according to claim 1, characterized in that The pigment is a colored paste.

3. The method for preparing the ultra-thin aluminum topcoat according to claim 1, characterized in that The catalyst is ammonium dodecylbenzenesulfonate; the leveling agent is an acrylate copolymer; the defoamer is an organic silicon or polyether defoamer; and the adhesion promoter is a silane promoter.

4. The method for preparing the ultra-thin aluminum topcoat according to any one of claims 1 to 3, characterized in that The method for preparing the ultra-thin aluminum topcoat is to prepare an ultra-thin aluminum coating using the ultra-thin aluminum topcoat. The specific method includes: rolling the ultra-thin aluminum topcoat onto the surface of the ultra-thin aluminum, baking it to dryness at 150°C-200°C, and the rolling coating thickness is 0.009-0.1mm.

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