A 3D mobile phone back cover pad printing ink, its preparation method and application

Abstract

The present invention discloses a pad printing ink for the back cover of a 3D mobile phone. The preparation raw materials include, by weight: 50 - 70 parts of acrylic resin, 10 - 20 parts of pigment, 10 - 20 parts of filler, 1 - 3 parts of adhesion promoter, 5 - 15 parts of curing agent, 1 - 10 parts of dispersant, and 1 - 5 parts of auxiliary agent. The present invention adopts the combination of polyester-modified acrylic resin and polyester-modified hydroxyl acrylic resin, which can improve the adhesion of 3D glass pad printing, improve the printing effect, the printing edge is neat and uniform, and there is no burr at the edge. The combination of talcum powder and matting powder is used as the filler, which can improve the printing resolution, improve the printing effect, the formed ink has strong aging resistance and solvent resistance, is not easy to peel off after being applied to the surface of 3D glass, and has excellent glossiness. The pad printing process is used for construction, the operation is simple, the printing frame and characters can be printed on the 3D curved glass, and it has excellent adhesion and weather resistance.

Description

Technical Field

[0001] The present invention relates to a pad printing ink for the back cover of a 3D mobile phone, a preparation method and an application thereof, relates to C09D, and specifically relates to the field of coating compositions. Background Art

[0002] With the diversification and refinement of electronic products, 3D glass can be used as the front cover plate for both smart phones and the instrument panels of wearable electronic products, which can improve the appearance fashion sense of terminal electronic products while having better touch feeling and user experience. However, the ordinary screen printing process can no longer meet the printing requirements of 3D cover plates, and the printing effect is poor at the concave arc of the 3D cover plate. The pad printing process can be used to achieve the surface printing of 3D glass. However, as the curvature of 3D glass increases step by step from the ordinary 50 degrees to 80 degrees or even higher, the traditional pad printing ink can no longer meet the printing of 3D glass with a higher curvature. Therefore, it is crucial to develop an ink suitable for printing on 3D glass with a large curvature, especially to optimize the ink supply effect at the concave arc and the ink supply property at the r corner position.

[0003] Chinese Patent CN201910911742.2 discloses an environment-friendly edge banding ink and a preparation method thereof, which uses a combination of acrylic resins with appropriate molecular weights and is combined with an anionic polymer dispersant to improve the resin strength and optimize the ink effect. However, it cannot achieve the printing of the concave surface of 3D glass. Chinese Patent CN201310086603.3 discloses an aqueous printing ink and its application. The introduced aminated acrylic resin solution is an excellent dispersion medium for organic pigments and inorganic pigments, and has excellent compatibility with acrylic polymer emulsions, and the aqueous printing effect is good, but it still cannot meet the printing requirements of the concave surface of 3D glass. Summary of the Invention

[0004] In order to improve the printing performance of the pad printing ink on the surface of 3D mobile phone glass, the first aspect of the present invention provides a pad printing ink for the back cover of a 3D mobile phone. The preparation raw materials include, by weight: 50-70 parts of acrylic resin, 10-20 parts of pigment, 10-20 parts of filler, 1-3 parts of adhesion promoter, 5-15 parts of curing agent, 1-10 parts of dispersant, and 1-5 parts of auxiliary agent.

[0005] As a preferred embodiment, the preparation raw materials include, by weight: 55-65 parts of acrylic resin, 10-14 parts of pigment, 10-14 parts of filler, 1-2 parts of adhesion promoter, 8-12 parts of curing agent, 4-6 parts of dispersant, and 1-2 parts of auxiliary agent.

[0006] As a preferred embodiment, the acrylic resin is a modified acrylic resin, and the modified acrylic resin is selected from one or a combination of hydroxy acrylic resin, polyester modified acrylic resin, polyester modified hydroxy acrylic resin, and silicone modified acrylic resin.

[0007] As a preferred embodiment, the viscosity of the polyester modified acrylic resin at 25 °C is 5000 - 7000 mPa·s, and the solid content is 40 - 60 wt%.

[0008] As a preferred embodiment, the viscosity of the polyester modified hydroxy acrylic resin at 25 °C is 15000 - 20000 mPa·s.

[0009] As a preferred embodiment, the acrylic resin is a combination of polyester modified acrylic resin and polyester modified hydroxy acrylic resin.

[0010] As a preferred embodiment, the weight ratio of the polyester modified acrylic resin to the polyester modified hydroxy acrylic resin is (10 - 30) : (30 - 50).

[0011] As a preferred embodiment, the weight ratio of the polyester modified acrylic resin to the polyester modified hydroxy acrylic resin is (15 - 25) : (35 - 45).

[0012] As a preferred embodiment, the weight ratio of the polyester modified acrylic resin to the polyester modified hydroxy acrylic resin is 20 : 40.

[0013] The applicant found during the experiment that the combination of two modified acrylic resins has good pad printing performance on 3D glass, can improve the adhesion of pad printing on 3D glass, improve the printing effect, and the printing edge is neat and uniform without burrs. It is speculated that the possible reason is: using a polyester-acrylic copolymer with a solid content of 50 wt% and a viscosity of 6000 mPa·s in combination with a polyester modified hydroxy acrylate resin with a viscosity of 16000 mPa·s, the viscosity of the prepared resin mother liquor is moderate, which can balance the viscosity and leveling performance, and maintain a good adhesion effect at the concave arc of the 3D glass, neither ink overflowing at the arc nor poor adhesion during leveling, thereby improving the pad printing performance at the concave arc of the 3D glass.

[0014] As a preferred embodiment, the pigment is carbon black.

[0015] As a preferred embodiment, the filler is selected from one or a combination of talc powder, matting powder, calcium carbonate, barium sulfate, and white carbon black.

[0016] As a preferred embodiment, the filler is a combination of talcum powder and matting powder.

[0017] As a preferred embodiment, the weight ratio of the talcum powder to the matting powder is (5 - 10):(1 - 5).

[0018] As a preferred embodiment, the weight ratio of the talcum powder to the matting powder is (7 - 9):(3 - 5).

[0019] As a preferred embodiment, the weight ratio of the talcum powder to the matting powder is 8:4.

[0020] The applicant further found that using a combination of talcum powder and matting powder as the filler can improve the printing resolution and enhance the printing effect. The reason may be that using a combination of talcum powder and matting powder as the filler can improve the solid dispersion effect of the ink, and the formed ink has strong aging resistance and solvent resistance. After being applied to the 3D glass surface, it is not easy to peel off and has excellent glossiness.

[0021] As a preferred embodiment, the adhesion promoter is a silane coupling agent, and the silane coupling agent is selected from one or a combination of bis - amino silane coupling agents, epoxy silane coupling agents, γ - glycidoxypropyltrimethoxysilane, N - β(aminoethyl)-γ - aminopropyltrimethoxysilane.

[0022] As a preferred embodiment, the adhesion promoter is an epoxy silane coupling agent.

[0023] As a preferred embodiment, the curing agent is selected from one or a combination of isocyanate curing agents, aliphatic amine curing agents, amidoamine curing agents, and aromatic amines.

[0024] As a preferred embodiment, the curing agent is an isocyanate curing agent. Preferably, the curing agent is an XDI isocyanate curing agent.

[0025] As a preferred embodiment, the dispersant is a polyurethane - modified dispersant.

[0026] As a preferred embodiment, the auxiliary agent is a leveling agent, and the leveling agent is an organosilicon leveling agent.

[0027] As a preferred embodiment, the fineness of the 3D mobile phone back cover pad printing ink is ≤8μm.

[0028] The second aspect of the present invention provides a method for preparing a 3D mobile phone back cover pad printing ink, comprising the following steps:

[0029] Add the preparation raw materials in sequence while dispersing at a dispersion speed of 200 - 400 r / min. After all the materials are added, disperse at a speed of 600 - 1000 r / min for 5 - 15 min, then grind, and filter through a 100 - 300 mesh filter screen to obtain the ink.

[0030] The third aspect of the present invention provides an application of a 3D mobile phone back cover pad printing ink in preparing the back cover glass or front cover glass of a 3D mobile phone.

[0031] As a preferred embodiment, the printing method of the 3D mobile phone back cover pad printing ink includes the following steps:

[0032] After transferring the 3D mobile phone back cover pad printing ink onto the front cover or back cover glass of the 3D mobile phone through the rubber head of a fully automatic pad printer, bake it at a temperature of 150°C - 180°C, keep it at a constant temperature for 30 min - 60 min, and cool it to obtain a coating with a thickness of 8 - 12 μm.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) For the 3D mobile phone back cover pad printing ink of the present invention, the combination of polyester - modified acrylic resin and polyester - modified hydroxyl acrylic resin can improve the adhesion of 3D glass pad printing, improve the printing effect, and the printing edges are neat and uniform without burrs.

[0035] (2) For the 3D mobile phone back cover pad printing ink of the present invention, the combination of talcum powder and matting powder is used as a filler, which can improve the printing resolution, enhance the printing effect, and the formed ink has strong anti - aging and solvent - resistant properties. It is not easy to peel off after being applied to the surface of 3D glass and has excellent glossiness.

[0036] (3) For the 3D mobile phone back cover pad printing ink of the present invention, the pad printing process is used for construction, the operation is simple, it can print borders and characters on 3D curved glass, has excellent adhesion and weather resistance, good printing edge performance, and is not prone to problems such as hair pulling and tooth loss. Specific Embodiments

[0037] The purchase manufacturers and models of the preparation raw materials in the examples are shown in Table 1.

[0038] Example 1

[0039] A 3D mobile phone back cover pad printing ink, the preparation raw materials include, by weight: 60 parts of acrylic resin, 12 parts of pigment, 12 parts of filler, 1 part of adhesion promoter, 10 parts of curing agent, 5 parts of dispersant, and 0.5 part of auxiliary agent.

[0040] The acrylic resin is a combination of polyester-modified acrylic resin and polyester-modified hydroxyl acrylic resin, with a weight ratio of 40:20. The viscosity of the polyester-modified acrylic resin at 25 °C is 6000 mPa·s, and the solid content is 50 wt%. The viscosity of the polyester-modified hydroxyl acrylic resin at 25 °C is 16000 mPa·s.

[0041] The pigment is carbon black.

[0042] The filler is a combination of talc powder and matting powder, with a weight ratio of 8:4.

[0043] The adhesion promoter is an epoxy silane coupling agent.

[0044] The curing agent is an XDI isocyanate curing agent.

[0045] The dispersant is a polyurethane-modified dispersant.

[0046] The auxiliary agent is a leveling agent, and the leveling agent is a silicone-based leveling agent.

[0047] A preparation method of a 3D mobile phone back cover pad printing ink, comprising the following steps:

[0048] The preparation raw materials are added while dispersing at a dispersion speed of 300 r / min in sequence. After all the materials are added, they are dispersed at a speed of 800 r / min for 10 min, and then ground with a horizontal three-roll mill. After detecting that the fineness is ≤8 μm, a curing agent is added to obtain the ink.

[0049] Example 2

[0050] A 3D mobile phone back cover pad printing ink and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the acrylic resin is a combination of polyester-modified acrylic resin and polyester-modified hydroxyl acrylic resin, with a weight ratio of 20:40.

[0051] Example 3

[0052] A 3D mobile phone back cover pad printing ink and its preparation method, the specific implementation manner is the same as that of Example 1, the difference is that the preparation raw materials include, by weight: 60 parts of acrylic resin, 12 parts of pigment, 12 parts of filler, 1 part of adhesion promoter, 10 parts of curing agent, 2 parts of dispersant, and 0.5 part of auxiliary agent.

[0053] Example 4

[0054] A 3D mobile phone back cover pad printing ink and its preparation method, the specific implementation manner is the same as that of Example 3, the difference is that the filler is a combination of talc powder and matting powder, with a weight ratio of 4:8.

[0055] Example 5

[0056] A 3D mobile phone back cover pad printing ink and its preparation method. The specific implementation manner is the same as that of Example 2, with the difference that the preparation raw materials include, by weight: 60 parts of acrylic resin, 16 parts of pigment, 12 parts of filler, 1 part of adhesion promoter, 10 parts of curing agent, 5 parts of dispersant, and 0.5 part of auxiliary agent.

[0057] Comparative Example 1

[0058] A 3D mobile phone back cover pad printing ink and its preparation method. The specific implementation manner is the same as that of Example 2, with the difference that the acrylic resin is a combination of polyester-modified acrylic resin and polyester-modified hydroxyl acrylic resin, and the weight ratio is 0:60.

[0059] Comparative Example 2

[0060] A 3D mobile phone back cover pad printing ink and its preparation method. The specific implementation manner is the same as that of Example 2, with the difference that the acrylic resin is a combination of polyester-modified acrylic resin and polyester-modified hydroxyl acrylic resin, and the weight ratio is 60:0.

[0061] Comparative Example 3

[0062] A 3D mobile phone back cover pad printing ink and its preparation method. The specific implementation manner is the same as that of Example 2, with the difference that the filler is talcum powder.

[0063] Comparative Example 4

[0064] A 3D mobile phone back cover pad printing ink and its preparation method. The specific implementation manner is the same as that of Example 2, with the difference that the filler is matting powder.

[0065] Comparative Example 5

[0066] A 3D mobile phone back cover pad printing ink and its preparation method. The specific implementation manner is the same as that of Example 2, with the difference that the preparation raw materials include, by weight: 60 parts of acrylic resin, 16 parts of pigment, 12 parts of filler, 0 part of adhesion promoter, 10 parts of curing agent, 5 parts of dispersant, and 0.5 part of auxiliary agent.

[0067] Table 1

[0068]

[0069] Performance test

[0070] After the 3D mobile phone back cover pad printing ink prepared in the examples and comparative examples is pad printed on the front or back cover glass of the 3D mobile phone through the rubber head of the full-automatic pad printer, it is baked at a temperature of 150 °C for 40 minutes of constant temperature, and then cooled to obtain a coating with a thickness of 8 - 12 μm. Observe the surface effect of the ink layer and the printing edge effect, and conduct performance detection.

[0071] 1. Adhesion test: The adhesion of the ink layers in the examples and comparative examples was tested according to the standard of GB / T 1720-79(89). The test results are shown in Table 2 below.

[0072] 2. Ink printing edge test: Observe under a microscope at 20 magnifications whether there are defects such as incomplete edges, fluffed edges, and oil splashing on the ink printing edges.

[0073] 3. Acetone resistance wiping test: Use a wear-resistant tester and wipe the ink surface 100 times with a gauze dipped in acetone under a load of 1 kg, and observe whether there are obvious dissolution, swelling, or delamination phenomena on the ink surface.

[0074] 4. Insulation value test: Use a GM3125 impedance tester to test the surface resistance of the printed board (the distance between two pens is 1 cm), and test whether the resistance can reach 2500V / >100GΩ.

[0075] 5. QUV aging resistance test: Use a QUV aging tester, set the program to 12 cycles, each cycle for 8 hours, including 4 hours of UV light exposure time (0.63W / m 2 / nm and 60 °C) and 4 hours of moisture exposure time. After the test is completed, let it stand at room temperature for two hours, observe whether there are obvious changes in the color and gloss of the glass surface, whether there are changes in the appearance of the ink surface, and test whether the conventional adhesion reaches level 1.

[0076] The test results are shown in Table 2 below.

[0077] Table 2

[0078]

[0079] Combined with the comparison of the performance test results of Examples 1-2 and Comparative Examples 1-2 in Table 2, it can be seen that the optimal performance ratio of using polyester-modified acrylic resin and polyester-modified hydroxyl acrylic resin in this application is 1:2; exceeding the ratio has a certain impact on the printing edge effect and acetone resistance.

[0080] Combined with the comparison of the performance test results of Example 2 and Comparative Examples 3-4 in Table 2, it can be seen that when using talcum powder or matting powder, talcum powder has lower thixotropic properties, and matting powder has higher thixotropic properties. Both low and high thixotropic properties of the ink system will cause printing defects such as ink overflow and incomplete edges. When the ratio of talcum powder to matting powder is 2:1, there is a better printing edge effect.

[0081] Combined with the comparison of the performance test results of Example 2 and Comparative Example 5 in Table 2, it can be seen that the use of an adhesion promoter has a greater impact on adhesion, and the adhesion promoter is a key factor for the adhesion of the ink system to the glass substrate.

Claims

1. A 3D mobile phone back cover pad printing ink, characterized in that: The raw materials for preparation include, by weight: 50-70 parts of acrylic resin, 10-20 parts of pigment, 10-20 parts of filler, 1-3 parts of adhesive, 5-15 parts of curing agent, 1-10 parts of dispersant, and 1-5 parts of auxiliary agent; The acrylic resin is a combination of polyester modified acrylic resin and polyester modified hydroxy acrylic resin, with a weight ratio of (10-30): (30-50); The viscosity of the polyester-modified acrylic resin at 25° C. is 5000-7000 mPa·s, and the solid content is 40-60 wt %; the viscosity of the polyester-modified hydroxyl acrylic resin at 25° C. is 15000-20000 mPa·s; The filler is a combination of talcum powder and matting powder, with a weight ratio of (5-10): (1-5).

2. The 3D mobile phone back cover pad printing ink according to claim 1, characterized in that: The adhesion agent is a silane coupling agent, and the silane coupling agent is selected from one or a combination of bisaminosilane coupling agents and epoxysilane coupling agents.

3. The 3D mobile phone back cover pad printing ink according to claim 1, characterized in that: The curing agent is selected from one or a combination of isocyanate curing agents, aliphatic amine curing agents, amide amine curing agents, and aromatic amines.

4. The 3D mobile phone back cover pad printing ink according to claim 1, characterized in that: The fineness of the 3D mobile phone back cover pad printing ink is ≤8μm.

5. A method for preparing the 3D mobile phone back cover pad printing ink according to any one of claims 1 to 4, characterized in that: The following steps are involved: The prepared raw materials are added in sequence at a dispersing speed of 200-400r / min while being dispersed. After the materials are completely added, they are dispersed at a speed of 600-1000r / min for 5-15min, then ground, and filtered through a 100-300 mesh filter to obtain ink.

6. Use of the 3D mobile phone back cover pad printing ink according to any one of claims 1 to 4 in preparing the back cover glass or front cover glass of a 3D mobile phone.

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