UV primer coating method for tinplate can and surface-treatment-free UV primer for tinplate can

Abstract

The invention discloses a UV primer coating method for a tinplate can and a surface-treatment-free UV primer for the tinplate can. The method comprises the steps that S1, the UV primer is prepared; s2, the surface, not subjected to surface oil removal treatment, of the tinplate can is directly coated with UV primer; and S3, ultraviolet light with the energy higher than 350 mJ / m < 2 > is adopted for curing the surface, coated with the primer, of the tinplate can till the surface is completely dried. The UV primer provided by the scheme can ensure that the tin can still has good adhesive force under the condition that the tin can is not subjected to oil removal pretreatment, and meanwhile, the UV primer has excellent scratch resistance, saline-alkaline water resistance, impact resistance and short curing speed.

Description

Technical Field

[0001] The invention relates to the field of tinplate, in particular to a UV primer coating method for tinplate cans and a UV primer for tinplate cans without surface treatment. Background Art

[0002] The existing tinplate can surface treatment process, such as the invention patent with publication number CN105714289A, usually purifies and oils the surface of the tinplate can after tin plating, so as to ensure that the tinplate can will not be rusted, oxidized and scratched before printing and coloring, and make the color ink close. The traditional primer currently used for tinplate cans is usually a heat-curing primer. This type of primer will emit a large amount of solvent during use, which is harmful to the human body and the environment. UV primer is cured by ultraviolet light, so there is no problem of solvent volatilization, and it does not need to use high heat curing, which is more environmentally friendly and energy-saving.

[0003] However, most existing UV primers have poor adhesion to tinplate, especially when anti-rust oil is applied to the surface of tinplate cans. If UV primer is directly applied, the impact resistance of UV primer after curing is poor. In view of the above problems, the solution in the prior art is to pre-treat the surface of tinplate cans, such as high-temperature baking, organic solvent wiping, etc.; high-temperature treatment, such as the invention patent with authorization announcement number CN103909754B, is to perform surface treatment on the metal can before UV primer coating and UV ink printing: the flame processor integrated in the front end of the UV iron printing machine is used to perform instant high-temperature treatment on the outer surface of the substrate of the UV primer metal can; it increases the processing steps and energy consumption, and the use of organic solvent wiping is prone to environmental pollution.

[0004] In addition, some tinplate cans used in the chemical industry need to be filled with saline and alkaline chemicals. Therefore, the coating on the surface of the tinplate cans must also have good chemical and saline resistance to ensure a wider range of applications. Summary of the invention

[0005] Therefore, in order to solve the above problems, the present invention provides a UV primer coating method for tinplate cans and a UV primer for tinplate cans without surface treatment.

[0006] The present invention is achieved through the following technical solutions:

[0007] The UV primer coating method for tinplate cans comprises the following steps:

[0008] S1: Preparation of UV primer;

[0009] S11: Prepare the following raw materials by mass:

[0010]

[0011] The leveling agent is composed of a leveling agent and a wetting agent in a mass ratio of 1:1, the active monomer includes a monofunctional active monomer and a bifunctional active monomer, and the mass ratio of the two is 2:1, and the particle size D50 of the wax powder is ≤3μm;

[0012] S12: firstly, uniformly mix the polyurethane acrylate, the active monomer and the photoinitiator prepared in step S11 to form a first mixture;

[0013] S13: adding a leveling agent, a lubricant, and an adhesion promoter to the first mixture and mixing the mixture at a rotation speed of ≥1000 rpm for 15 minutes to form a second mixture;

[0014] S14: adding wax powder to the second mixture and mixing at a rotation speed of ≥1000 rpm for 30 minutes to obtain a UV primer;

[0015] S2: directly coating the UV primer on the surface of the tinplate can that has not been subjected to surface degreasing treatment;

[0016] S3: Energy used is higher than 350mJ / m 2 The surface of the tinplate can coated with primer is cured by ultraviolet light until it is completely dry.

[0017] Preferably, step S1 and step S2 are completed at a temperature below 40°C.

[0018] UV primer for tinplate cans without surface treatment, including the following raw materials in parts by mass:

[0019]

[0020] The leveling agent is composed of a leveling agent and a wetting agent in a mass ratio of 1:1, the active monomers include a monofunctional active monomer and a bifunctional active monomer in a mass ratio of 2:1, and the particle size D50 of the wax powder is ≤3 μm.

[0021] Preferably, the polyurethane acrylate is LuCure5956 produced and sold by Guangzhou Runao Chemical Materials Co., Ltd.

[0022] Preferably, the polyurethane acrylate is prepared by mixing LuCure5956 and LuCure5698 produced and sold by Guangzhou Runao Chemical Materials Co., Ltd. in a ratio of 5:1.

[0023] Preferably, the leveling agent is TEGO Rad2300 produced and sold by Evonik Degussa Specialty Chemicals (Shanghai) Co., Ltd. and the wetting agent is BYK-UV 3500 produced and sold by BYK-Chemie GmbH in Germany, mixed in equal proportions.

[0024] Preferably, the active monomers include a monofunctional active monomer IBOA and a difunctional active monomer HDDA, and the mass ratio of the two is 2:1.

[0025] Preferably, the photoinitiator includes photoinitiator 1173 and photoinitiator TPO in an equal weight ratio.

[0026] Preferably, the wax powder is micronized PTFE modified wax with a product grade of 2380 produced and sold by Jiangxi Longhai Chemical Co., Ltd.

[0027] Preferably, the adhesion promoter is methacrylate phosphate.

[0028] The beneficial effects of the technical solution of the present invention are mainly reflected in:

[0029] 1. This scheme uses polyurethane acrylate as the main resin, which has a low shrinkage rate and good adhesion to metal. It also has a fast curing speed, good hardness and flexibility, and excellent salt and alkali resistance. Its molecular properties can effectively improve the impact resistance. At the same time, monofunctional monomers and difunctional monomers are selected as active diluents to adjust the primer to a suitable viscosity, further improving the overall adhesion of the primer.

[0030] 2. This scheme adds an adhesion promoter. The adhesion promoter uses methacrylate phosphate, which can further improve the compactness and water repellency of the film-forming material and increase the water resistance of the primer, thereby ensuring that the primer maintains its performance in a humid or water environment after curing. In addition, methacrylate phosphate can undergo free radical copolymerization with acrylate or methacrylate monomers, oligomers and unsaturated resins under the initiation of ultraviolet light or organic peroxides, and can have a slight phosphating effect on the metal substrate, which is beneficial to bonding with the tinplate surface and improving the adhesion on the surface of the tinplate can. It can significantly improve the adhesion and adhesion of the paint, avoid the problem of paint falling off during use, and enhance the flexibility and corrosion resistance of the paint film. In addition, methacrylate phosphate has good compatibility and storage stability. Therefore, the UV primer can be directly applied without degreasing the surface of the tinplate can.

[0031] 3. In this scheme, the leveling agent and the wetting agent are mixed in equal proportions, which can reduce the surface tension of the UV primer, make the UV primer have better wettability, and promote the leveling of the UV primer on the surface of the tinplate can, ensuring the appearance of the coating after curing. In addition, by adding fine wax powder, the dispersibility of the UV primer can be further improved, and the anti-scratch effect of the UV primer after curing can be improved. DETAILED DESCRIPTION

[0032] In order to make the purpose, advantages and features of the present invention more clearly and in detail, the following non-limiting description of the preferred embodiment will be used for explanation. The embodiment is only a typical example of the application of the technical solution of the present invention, and any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection claimed by the present invention.

[0033] In addition, the terms "first" and "second" in this solution are only used for descriptive purposes and cannot be understood as indicating or implying the order of importance, or implicitly indicating the number of technical features shown. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0034] The present invention discloses a UV primer coating method for tinplate cans, comprising the following steps:

[0035] S1: Preparation of UV primer;

[0036] S11: Prepare the following raw materials by mass:

[0037]

[0038] The leveling agent is composed of a leveling agent and a wetting agent in a mass ratio of 1:1, the active monomer includes a monofunctional active monomer and a bifunctional active monomer, and the mass ratio of the two is 2:1, and the particle size D50 of the wax powder is ≤3μm;

[0039] S12: firstly, uniformly mix the polyurethane acrylate, the active monomer and the photoinitiator prepared in step S11 to form a first mixture;

[0040] S13: adding a leveling agent, a lubricant, and an adhesion promoter to the first mixture and mixing the mixture at a rotation speed of ≥1000 rpm for 15 minutes to form a second mixture;

[0041] S14: adding wax powder to the second mixture and mixing at a rotation speed of ≥1000 rpm for 30 minutes to obtain a UV primer;

[0042] S2: directly coating the UV primer on the surface of the tinplate can that has not been subjected to surface degreasing treatment;

[0043] S3: Energy used is higher than 350mJ / m 2 The surface of the tinplate can coated with primer is cured by ultraviolet light until it is completely dry.

[0044] Preferably, step S1 and step S2 are completed at a temperature below 40°C.

[0045] The present invention also discloses a UV primer for tinplate cans without surface treatment, comprising the following raw materials in parts by mass:

[0046]

[0047] The leveling agent is composed of a leveling agent and a wetting agent in a mass ratio of 1:1, the active monomers include a monofunctional active monomer and a bifunctional active monomer in a mass ratio of 2:1, and the particle size D50 of the wax powder is ≤3 μm.

[0048] In some embodiments, after the above raw materials are prepared, the method for preparing the UV primer for tinplate cans without surface treatment further comprises the following steps:

[0049] Step I: at a temperature below 40° C., firstly, uniformly mix the polyurethane acrylate, the active monomer and the photoinitiator prepared in step S11 to form a first mixture;

[0050] Step II: adding a leveling agent, a lubricant, and an adhesion promoter to the first mixture and mixing at a speed of ≥1000 rpm for 15 minutes to form a second mixture;

[0051] Step III: Add wax powder to the second mixture and mix at a rotation speed of ≥1000 rpm for 30 minutes to obtain a UV primer.

[0052] In some embodiments, the polyurethane acrylate is LuCure5956 produced and sold by Guangzhou Runao Chemical Materials Co., Ltd., the leveling agent is TEGO Rad2300 produced and sold by Evonik Degussa Specialty Chemicals (Shanghai) Co., Ltd. and the wetting agent is BYK-UV 3500 produced and sold by BYK-Chemie GmbH of Germany, mixed in equal proportions, the active monomer includes a monofunctional active monomer IBOA and a difunctional active monomer HDDA, and the mass ratio of the two is 2:1, the photoinitiator includes a photoinitiator 1173 and a photoinitiator TPO of an equal mass ratio, the wax powder adopts a micronized PTFE modified wax with a product grade of 2380 produced and sold by Jiangxi Longhai Chemical Co., Ltd., and the adhesion promoter is methyl methacrylate phosphate.

[0053] With respect to the above raw materials and preparation methods, the following embodiments are provided:

[0054] Embodiment 1:

[0055] Provided is a UV primer for tinplate cans without surface treatment, comprising the following raw materials in parts by mass:

[0056]

[0057] Among them, the polyurethane acrylate is LuCure5956 produced and sold by Guangzhou Runao Chemical Materials Co., Ltd., the leveling agent is composed of a leveling agent and a wetting agent in a mass ratio of 1:1, the active monomer includes a monofunctional active monomer IBOA and a difunctional active monomer HDDA, and the mass ratio of the two is 2:1, the wax powder uses a wax powder with a D50 particle size of ≤3μm, and the adhesion promoter is methyl methacrylate phosphate.

[0058] In some embodiments, after the above raw materials are prepared, the method for preparing the UV primer for tinplate cans without surface treatment further comprises the following steps:

[0059] Step I: at a temperature below 40° C., firstly, uniformly mix the polyurethane acrylate, the active monomer and the photoinitiator prepared in step S11 to form a first mixture;

[0060] Step II: adding a leveling agent, a lubricant, and an adhesion promoter to the first mixture and mixing at a speed of ≥1000 rpm for 15 minutes to form a second mixture;

[0061] Step III: Add wax powder to the second mixture and mix at a rotation speed of ≥1000 rpm for 30 minutes to obtain the UV primer of Example 1.

[0062] Embodiment 2:

[0063] Provided is a UV primer for tinplate cans without surface treatment, comprising the following raw materials in parts by mass:

[0064]

[0065] The leveling agent is composed of a leveling agent and a wetting agent in a mass ratio of 1:1, the active monomers include a monofunctional active monomer and a bifunctional active monomer in a mass ratio of 2:1, and the particle size D50 of the wax powder is ≤3 μm.

[0066] Among them, the polyurethane acrylate is mixed with LuCure5956 and LuCure5698 produced and sold by Guangzhou Runao Chemical Materials Co., Ltd. in a ratio of 5:1, the leveling agent is TEGO Rad 2300 produced and sold by Evonik Degussa Specialty Chemicals (Shanghai) Co., Ltd. and the wetting agent is BYK-UV 3500 produced and sold by German BYK Chemical Co., Ltd. in equal proportions, the active monomer includes a monofunctional active monomer IBOA and a difunctional active monomer HDDA, and the mass ratio of the two is 2:1, the photoinitiator includes a photoinitiator 1173 and a photoinitiator TPO of an equal mass ratio, the wax powder adopts a micronized PTFE modified wax with a product brand number 2380 produced and sold by Jiangxi Longhai Chemical Co., Ltd., and the adhesion promoter is methyl methacrylate phosphate.

[0067] In some embodiments, after the above raw materials are prepared, the method for preparing the UV primer for tinplate cans without surface treatment further comprises the following steps:

[0068] Step I: at a temperature below 40° C., firstly, uniformly mix the polyurethane acrylate, the active monomer and the photoinitiator prepared in step S11 to form a first mixture;

[0069] Step II: adding a leveling agent, a lubricant, and an adhesion promoter to the first mixture and mixing at a speed of ≥1000 rpm for 15 minutes to form a second mixture;

[0070] Step III: Add wax powder to the second mixture and mix at a rotation speed of ≥1000 rpm for 30 minutes to obtain the UV primer of Example 2.

[0071] Two tinplate substrates subjected to degreasing pretreatment and two tinplate substrates not subjected to degreasing pretreatment were respectively provided, wherein the degreasing pretreatment of the tinplate substrates was baking the tinplate substrates at 180° C. for 20 minutes; then the UV primer of Example 1 and the UV primer of Example 2 were uniformly coated on the tinplate substrates subjected to degreasing pretreatment and the tinplate substrates not subjected to degreasing pretreatment, respectively, and then the tinplate substrates were heated with an energy higher than 350 mJ / m 2 The UV primer is cured by ultraviolet light until it is completely dry.

[0072] At the same time, a UV printing method for a UV primer metal can disclosed in the invention with authorization announcement number CN103909754B is used as a comparative example of the existing UV primer. First, the tinplate substrate is subjected to substrate surface treatment according to the processing method disclosed in the invention, and then the UV primer prepared according to the formula of the invention is coated on the surface of the treated tinplate substrate, and a UV lamp with a power of 160W-200W / CM is used, the lamp power is 100%, the curing time is 1 second, and the coated UV primer outer coating is cured to obtain a UV primer comparison product in which the tinplate substrate is pre-treated for degreasing; subsequently, a tinplate substrate that has not been subjected to substrate surface treatment is used, and a UV primer is coated on the surface of the tinplate substrate that has not been subjected to substrate surface treatment, and a UV lamp with a power of 160W-200W / CM is used, the lamp power is 100%, the curing time is 1 second, and the coated UV primer outer coating is cured to obtain a comparative product in which the tinplate substrate is not pre-treated for degreasing.

[0073] A tinplate substrate that has been pre-treated for degreasing and a tinplate substrate that has not been pre-treated for degreasing are respectively provided, wherein the pre-treatment for degreasing the tinplate substrate is to bake the tinplate substrate at 180°C for 20 minutes; then, a heat-curing primer (the heat-curing primer uses GS-29 series gold primer) is coated on the tinplate substrate that has been pre-treated for degreasing and the tinplate substrate that has not been pre-treated for degreasing, respectively, and the tinplate substrates coated with the heat-curing primer are placed in an oven at 180°C and baked for 10 minutes to 12 minutes.

[0074] Subsequently, all tinplate substrates that have completed primer curing were subjected to adhesion tests (national standard GB / T9286-2021 paint and varnish cross-cut test); and the tinplate substrates that have completed primer curing after pretreatment were subjected to impact resistance (GB-T 1732-1993 paint film impact resistance determination method), salt and alkaline water resistance test (the tinplate substrate was immersed in a NaCl solution with a pH value of 12 and a concentration of 3%, and observed for 20 days) and scratch resistance test (GB / T 31591-2015 Determination of the abrasion resistance of paint and varnish). The test results are as follows:

[0075]

[0076]

[0077] According to the above test results, the above-mentioned UV primers and heat-curing primers have good adhesion on the tinplate substrates that have been pre-treated before degreasing, but the existing UV primers cannot be used on the tinplate substrates that have not been pre-treated before degreasing, and the adhesion of the heat-curing primer on the tinplate substrates that have not been pre-treated before degreasing is also slightly reduced. At the same time, the curing speed of the heat-curing primer is slow, and the salt and alkali water resistance of the heat-curing primer and the existing UV primer is significantly poor. The UV primer of Example 1 of the present invention and the UV primer of Example 2 have excellent adhesion on the tinplate substrates that have not been pre-treated and have been pre-treated, and have excellent scratch resistance, salt and alkali water resistance, impact resistance and a shorter curing speed.

[0078] There are many implementation methods of the present invention, and all technical solutions formed by equivalent transformation or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A UV primer coating method for tinplate cans, characterized in that: The steps include: S1: Preparation of UV primer; S11: Prepare the following raw materials by mass: Polyurethane acrylate 40-60 parts; Active monomer 20-35 parts; Photoinitiator 5-15 parts; Leveling agent 0.4-0.5 parts; Adhesion promoter 1.5-2 parts; 0.5-1 part wax powder; The leveling agent is composed of a leveling agent and a wetting agent in a mass ratio of 1:1, the active monomer includes a monofunctional active monomer and a bifunctional active monomer, and the mass ratio of the two is 2:1, and the particle size D50 of the wax powder is ≤3µm; S12: firstly, uniformly mix the polyurethane acrylate, the active monomer and the photoinitiator prepared in step S11 to form a first mixture; S13: adding a leveling agent, a lubricant, and an adhesion promoter to the first mixture and mixing the mixture at a rotation speed of ≥1000 rpm for 15 minutes to form a second mixture; S14: adding wax powder to the second mixture and mixing at a rotation speed of ≥1000 rpm for 30 minutes to obtain a UV primer; S2: directly coating the UV primer on the surface of the tinplate can that has not been subjected to surface degreasing treatment; S3: Energy used is higher than 350mJ / m 2 The surface of the tinplate can coated with primer is cured by ultraviolet light until it is completely dry.

2. The UV primer coating method for tinplate cans according to claim 1, characterized in that: Step S1 and step S2 are completed at a temperature below 40°C.

3. UV primer for tinplate cans without surface treatment, characterized by: Including the following raw materials by mass: Polyurethane acrylate 40-60 parts; Active monomer 20-35 parts; Photoinitiator 5-15 parts; Leveling agent 0.4-0.5 parts; Adhesion promoter 1.5-2 parts; 0.5-1 part wax powder; The leveling agent is composed of a leveling agent and a wetting agent in a mass ratio of 1:1, the active monomers include a monofunctional active monomer and a bifunctional active monomer in a mass ratio of 2:1, and the particle size D50 of the wax powder is ≤3µm.

4. The UV primer for tinplate cans without surface treatment according to claim 3, characterized in that: The polyurethane acrylate is LuCure5956 produced and sold by Guangzhou Runao Chemical Materials Co., Ltd.

5. The UV primer for tinplate cans without surface treatment according to claim 3, characterized in that: The polyurethane acrylate is prepared by mixing LuCure5956 and LuCure5698 produced and sold by Guangzhou Runao Chemical Materials Co., Ltd. in a ratio of 5:

1.

6. The UV primer for tinplate cans without surface treatment according to claim 3, characterized in that: The leveling agent is a mixture of TEGO Rad 2300 produced and sold by Evonik Degussa Specialty Chemicals (Shanghai) Co., Ltd. and BYK-UV 3500 produced and sold by BYK-Chemie GmbH of Germany in equal proportions.

7. The UV primer for tinplate cans without surface treatment according to claim 3, characterized in that: The active monomers include a monofunctional active monomer IBOA and a difunctional active monomer HDDA, and the mass ratio of the two is 2:

1.

8. The UV primer for tinplate cans without surface treatment according to claim 3, characterized in that: The photoinitiator includes photoinitiator 1173 and photoinitiator TPO in an equal weight ratio.

9. The UV primer for tinplate cans without surface treatment according to claim 3, characterized in that: The wax powder adopts micronized PTFE modified wax with a product grade of 2380 produced and sold by Jiangxi Longhai Chemical Co., Ltd.

10. The UV primer for tinplate cans without surface treatment according to claim 3, characterized in that: The adhesion promoter is methacrylate phosphate.

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