An Ink Preparation Method and Application Suitable for In-Mold Decoration (IMD) Process

Abstract

The present invention discloses a method for preparing an ink applicable to in-mold injection molding IMD process and its application, belonging to the technical field of inks. The ink of the present invention comprises component A and component B; component A comprises the following raw materials: thermoplastic saturated polyester resin, dispersant, and adhesion promoter; the glass transition temperature of the thermoplastic saturated polyester resin is 60-70 °C, and the hydroxyl content is 20-30 mgKOH / g; component B is an isocyanate curing agent. By compounding a specific thermoplastic saturated polyester resin and an isocyanate curing agent, the coating obtained after curing the ink prepared by the present invention has excellent high-temperature resistance and tensile resistance. After printing, the ink coating of the present invention enables the pattern to have excellent abrasion resistance, makes the pattern present gorgeous colors, and the VOC emission of the ink of the present invention is low during application, which is energy-saving and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of inks, and particularly relates to a method for preparing an ink applicable to the in-mold injection molding IMD process and its application. Background Art

[0002] In-mold decoration (IMD) technology, also known as spray-free technology, is a common plastic surface decoration technology at present and is widely used in replacing fields such as painting and electroplating processing of plastic products. This technology involves printing an ink on a plastic sheet to obtain a pattern, then cutting the required part by stamping and cutting, and finally placing the cut sheet in a mold cavity for injection molding, so that the injection resin combines with the printed ink layer on the back of the sheet; for the product obtained by this method, the ink pattern is placed between the sheet and the injection-molded resin, and the resin and the sheet are joined together as a whole, that is, the product surface is a hardened transparent film, the middle is an ink pattern layer, and the back is an injection layer. IMD has relatively high requirements for the performance of the ink. Especially in the fields of mobile phones and in-vehicle displays of new energy vehicles, etc., it is required that the cured ink has excellent elongation performance and high temperature resistance.

[0003] In view of the above performance requirements of the IMD process for the ink, developing an ink applicable to IMD technology, with excellent wear resistance of the printed pattern, gorgeous pattern colors, low volatile organic compound (VOC) emissions, and energy conservation and environmental protection is the current research focus in the ink field. Summary of the Invention

[0004] Based on the defects existing in the prior art, the purpose of the present invention is to provide a method for preparing an ink applicable to the in-mold injection molding IMD process and its application. The ink applicable to the in-mold injection molding IMD process is applicable to IMD technology, has excellent wear resistance of the printed pattern, can make the pattern colors gorgeous, and has the advantages of low VOC emissions, energy conservation and environmental protection.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] An ink applicable to the in-mold injection molding IMD process, the ink applicable to the in-mold injection molding IMD process includes component A and component B;

[0007] Component A includes the following raw materials: thermoplastic saturated polyester resin, dispersant, adhesion promoter;

[0008] The glass transition temperature (Tg) of the thermoplastic saturated polyester resin is 60 - 70 °C, and the hydroxyl content is 20 - 30 mgKOH / g;

[0009] Component B is an isocyanate curing agent.

[0010] The polyester resin used in the present invention is a thermoplastic saturated polyester resin. Thermoplastic saturated polyester has excellent adhesion to PET substrates and PC substrates, and it can be cured under low-temperature conditions of 60 - 80 °C. Therefore, when printed on the surface of plastic products, the products will not deform due to excessive curing temperature. At the same time, the molecular structure of the saturated polyester resin is a linear polymer, so the subsequently prepared ink coating can have excellent toughness and tensile resistance, so that the product will not crack during thermoforming.

[0011] The inventors found that when the Tg of the thermoplastic saturated polyester resin of the present invention is 60 - 70 °C and the hydroxyl content is 20 - 30 mgKOH / g, the hardness of the ink coating can be higher and the high-temperature resistance performance can be more excellent. At the same time, by compounding the above-mentioned specific thermoplastic saturated polyester resin and an isocyanate curing agent, the isocyanate curing agent has excellent aging resistance performance, low-temperature rapid curing characteristics, and the cured coating has good toughness and chemical resistance. The compounding of the two can make the cured ink coating have a certain degree of crosslinking, and when the hydroxyl content of the thermoplastic saturated polyester resin is 20 - 30 mgKOH / g, the crosslinking degree with the curing agent is higher, making the high-temperature resistance performance of the ink coating better. If the hydroxyl content of the thermoplastic saturated polyester resin is too large, it will lead to too high crosslinking degree between the two, resulting in a decrease in the adhesion of the final ink coating and poor toughness.

[0012] As a preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, based on the ink applicable to the in-mold injection molding IMD process, the weight parts of each raw material in the component A are: 25 - 45 parts of thermoplastic saturated polyester resin, 3 - 7 parts of dispersant, 0.5 - 4 parts of adhesion promoter; the weight part of the component B is 8 - 12 parts.

[0013] As a more preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, based on the ink applicable to the in-mold injection molding IMD process, the weight parts of each raw material in the component A are: 30 - 40 parts of thermoplastic saturated polyester resin, 4 - 5 parts of dispersant, 1 - 2 parts of adhesion promoter; the weight part of the component B is 8 - 12 parts; The inventors found through a large number of experiments that the compounding of each raw material within the above preferred weight part range can make the comprehensive performance of the final ink more excellent.

[0014] As a preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the component B is an XDI type isocyanate curing agent.

[0015] As a preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the adhesion promoter is a silane coupling agent; the inventor found through a large number of experiments that the silane coupling agent contains a silicon-oxygen bond, which can connect inorganic groups and organic groups, and tightly combine inorganic materials and organic materials. Therefore, the adhesion promoter of the present invention builds a molecular bridge between the ink and the substrate, and can sufficiently increase the adhesion of the ink to the substrate.

[0016] As a more preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the adhesion promoter is selected from at least one of vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-epoxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0017] As a preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the ink applicable to the in-mold injection molding IMD process further includes 30-40 parts of pigment, 1-2 parts of processing aids, and 5-10 parts of filler.

[0018] As a more preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the processing aids include an antifoaming agent and a leveling agent.

[0019] As the most preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the leveling agent is an acrylate leveling agent.

[0020] As a more preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the dispersant is a polyurethane dispersant, and the filler is talc.

[0021] As a more preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the pigment is rutile titanium dioxide.

[0022] As a more preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the ink applicable to the in-mold injection molding IMD process further includes a solvent.

[0023] As the most preferred embodiment of the ink applicable to the in-mold injection molding IMD process of the present invention, the solvent is a 1:1 compound of isophorone and solvent naphtha No. 150.

[0024] Second, the present invention provides a preparation method of the ink applicable to the in-mold injection molding IMD process as described in the first aspect, and the preparation method includes the following steps:

[0025] Mix the raw materials in the A component of the ink applicable to the in-mold injection molding IMD process evenly, then grind and filter to obtain the A component;

[0026] Mix component A and component B evenly to obtain the ink applicable to the in-mold injection IMD process.

[0027] As a preferred embodiment of the preparation method of the ink applicable to the in-mold injection IMD process of the present invention, the fineness of the grinding of component A is ≤7 μm.

[0028] As a more preferred embodiment of the preparation method of the ink applicable to the in-mold injection IMD process of the present invention, the specific process of grinding component A is as follows: Mix the raw materials in component A of the ink applicable to the in-mold injection IMD process at a dispersion speed of 200 - 400 r / min, continue to disperse at a speed of 600 - 1000 r / min for 10 min after mixing, then grind 4 times until the fineness is ≤7 μm, and finally filter through a 100 - 300 mesh filter to obtain component A.

[0029] In the third aspect, the present invention provides the application of the ink applicable to the in-mold injection IMD process as described in the first aspect in the in-mold injection IMD process.

[0030] As a preferred embodiment of the application of the ink applicable to the in-mold injection IMD process of the present invention in the in-mold injection IMD process, print the ink applicable to the in-mold injection IMD process described in the first aspect on a PET or PC film, with a printed film thickness of 20 - 30 μm, and then bake at a temperature of 60 - 80 °C for 90 min to obtain the required ink layer for the in-mold injection IMD process.

[0031] As a more preferred embodiment of the application of the ink applicable to the in-mold injection IMD process of the present invention in the in-mold injection IMD process, cut the required part of the PET / PC film product printed with the ink by stamping and cutting, place the cut sheet in the mold cavity for injection molding, the injection resin combines with the printed ink layer on the back of the sheet, the ink pattern is between the sheet and the injection-molded resin, and the resin and the sheet are bonded together and cured to form a solid, then a qualified IMD product can be obtained.

[0032] The beneficial effects of the present invention are as follows:

[0033] The present invention provides an ink applicable to the in-mold injection IMD process. By using a specific thermoplastic saturated polyester resin and an isocyanate curing agent in combination, the cured coating of the obtained ink has excellent high-temperature resistance and tensile resistance. The ink coating described in the present invention can make the pattern have excellent wear resistance after printing, make the pattern present gorgeous colors, and the VOC emission of the ink in the present invention during application is low, which is energy-saving and environmentally friendly. Specific Embodiments

[0034] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific examples and comparative examples. The purpose is to understand the content of the present invention in detail, rather than a limitation to the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention are all common ordinary reagents and instruments unless otherwise specified.

[0035] Among them, the processing aids are selected as a leveling agent and an antifoaming agent, and the mass ratio of the two is 1:1; the solvent is a compound of isophorone and solvent naphtha No. 150 with a mass ratio of 1:1.

[0036] In the components of each example and comparative example:

[0037] Thermoplastic saturated polyester resin 1: Tg is 62 °C, hydroxyl content is 30 mgKOH / g, FC916A, Mitsubishi Corporation, Japan.

[0038] Thermoplastic saturated polyester resin 2: Tg is 65 °C, hydroxyl content is 20 mgKOH / g, 226, Toyobo Co., Ltd., Japan.

[0039] Polyester resin 3: Tg is 78 °C, hydroxyl content is 18 mgKOH / g, ES600, SK Corporation, South Korea.

[0040] Polyester resin 4: Tg is 42 °C, hydroxyl content is 20 mgKOH / g, ES900M, SK Corporation, South Korea.

[0041] Curing agent 1: XDI type isocyanate curing agent, NCO content is 11.5, D-110N, Mitsui Chemicals, Japan.

[0042] Curing agent 2: IPDI type isocyanate curing agent, NCO content is 11.9, Z4470BA, Covestro AG, Germany.

[0043] Adhesion promoter: 3-glycidoxypropyltriethoxysilane, SCA-E87E, Nanjing Nengde Chemical Co., Ltd.

[0044] Dispersant: Modified polyurethane, commercially available.

[0045] Leveling agent / antifoaming agent: Degussa 4100 / Degussa 900, modified polyether silicone.

[0046] Pigment: Rutile titanium dioxide, commercially available.

[0047] Filler: Talc powder, commercially available.

[0048] Examples 1-5 and Comparative Examples 1-3

[0049] Examples 1-5 and Comparative Examples 1-3 are inks of the present invention applicable to the in-mold injection IMD process; the components and weight parts of the inks applicable to the in-mold injection IMD process in Examples 1-5 and Comparative Examples 1-3 are shown in Tables 1 and 2.

[0050] The preparation method of the inks applicable to the in-mold injection IMD process in Examples 1-5 and Comparative Examples 1-3 includes the following steps:

[0051] Mix the raw materials in component A of the ink applicable to the in-mold injection IMD process evenly, then grind and filter to obtain component A;

[0052] Mix component A and component B evenly to obtain the ink applicable to the in-mold injection IMD process.

[0053] The fineness of the grinding of component A ≤ 7μm.

[0054] Table 1

[0055]

[0056]

[0057] Table 2

[0058]

[0059] Effect Example 1

[0060] In order to verify the performance of the products of the present invention, the products of each example and comparative example are subjected to the following performance tests, and the specific steps are as follows:

[0061] Stir component A and component B of the ink evenly according to a mass ratio of 10:1, then screen-print on the surface of the plastic product with a 300-mesh screen. After the surface is dried at a baking temperature of 80°C for 5-10 minutes, print twice again with the same process. The dry film thickness after printing 3 times is 25-35um, and bake at 80°C for 90 minutes to obtain the required ink layer applicable to the in-mold injection IMD process.

[0062] (1) Adhesion test: According to the standard of GB / T 1720-79(89), the adhesion ≤ grade 1 is regarded as qualified.

[0063] (2) Elongation at break test: Test according to the standard of GB / T 1040.3. The required elongation at break ≥ 200% is regarded as qualified, and the higher the elongation rate, the better the performance.

[0064] (3) Alcohol resistance friction test: According to the standard of GB / T 23989, use 95% anhydrous ethanol, and rub back and forth on the surface of the product with a load of 500 grams for one cycle. If the ink surface is not worn through after 50 cycles, it is regarded as qualified.

[0065] The test results are shown in Table 3.

[0066] Table 3

[0067] Test performance Adhesion Elongation at break (%) Number of alcohol rubs resistance Example 1 Level 1 220％ 100 times Example 2 Level 1 200％ 100 times Example 3 Level 1 240％ 100 times Example 4 Level 0 260％ 100 times Example 5 Level 1 210％ 100 times Comparative Example 1 Level 1 120％ 100 times Comparative Example 2 Level 2 220％ 50 times Comparative Example 3 Level 2 180％ 50 times

[0068] As can be seen from Table 3, when the technical solution of the present invention is adopted, the ink applicable to the in-mold injection molding IMD process obtained has excellent adhesion rate, elongation at break, and alcohol rubbing resistance; specifically: the adhesion is all ≤ level 1, the elongation at break is ≥ 200%, and in the alcohol rubbing resistance test, the number of rubs on the product surface with a 500-gram load can reach 100 times.

[0069] Comparing Examples 1-2 with Comparative Examples 1 and 2, it can be seen that the Tg and hydroxyl content of the thermoplastic saturated polyester resin have an obvious impact on the comprehensive performance of the product; the Tg and hydroxyl content of the thermoplastic saturated polyester resin described in Examples 1 and 2 are within the range provided by the present invention, and the adhesion, elongation at break, and alcohol rubbing resistance of the final product are better.

[0070] Comparing Example 1 with Comparative Example 3, it can be seen that the specific curing agent has an obvious impact on the comprehensive performance of the product; the curing agent described in Example 1 adopts the curing agent selected by the present invention, and the adhesion, elongation at break, and alcohol rubbing resistance of the final product are better.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An IMD ink, characterized in that, The IMD ink includes component A and component B; Component A includes the following raw materials: thermoplastic saturated polyester resin, dispersant, and adhesion promoter; The glass transition temperature of the thermoplastic saturated polyester resin is 62 - 70 °C, and the hydroxyl content is 20 - 30 mgKOH / g; Component B is an XDI type isocyanate curing agent; Based on the IMD ink, the weight parts of each raw material in component A are: 30 - 40 parts of thermoplastic saturated polyester resin, 4 - 5 parts of dispersant, and 1 - 2 parts of adhesion promoter; the weight part of component B is 8 - 12 parts; The IMD ink further includes 30 - 40 parts of pigment, 1 - 2 parts of processing aid, and 5 - 10 parts of filler; The processing aid includes defoamer and leveling agent; The ink applicable to the in - mold injection IMD process further includes a solvent, and the solvent is a compound of isophorone and solvent naphtha No. 150 with a mass ratio of 1:

1.

2. The IMD ink according to claim 1, wherein The adhesion promoter is a silane coupling agent; The adhesion promoter is selected from at least one of vinyltrimethoxysilane, vinyltriethoxysilane, 3 - glycidoxypropyltrimethoxysilane, 3 - epoxypropyltrimethoxysilane, 3 - mercaptopropyltrimethoxysilane; 3. The IMD ink according to claim 1, wherein, The dispersant is a polyurethane - type dispersant; 4. The preparation method of the IMD ink according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: Mix the raw materials in component A of the IMD ink evenly, then grind and filter to obtain component A; Mix component A and component B evenly to obtain the IMD ink.

5. The preparation method of the IMD ink according to claim 4, characterized in that, The fineness of the grinding of component A is ≤7 μm.

6. The application of the IMD ink according to any one of claims 1 - 3 in the in - mold injection IMD process.

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