A front method for protecting mobile phone back cover glass from acid etching

Abstract

The application provides a front method for acid etching protection of a mobile phone back cover glass, which sprays a layer of water-soluble protective ink on the 3D glass convex surface of the mobile phone back cover glass, so as to reduce the adverse points caused by the splashing of acid-resistant protective ink to the 3D glass convex surface when spraying the acid-resistant protective ink, and the overall method is simple and easy to implement, and can greatly reduce the glass failure rate caused by the splashing of acid-resistant protective ink. The water-soluble protective ink comprises the following components according to 100 parts by mass: water-soluble acrylate oligomer 80-90 parts, wetting agent 0.1-0.5 parts, defoaming agent 1-2 parts, color paste 0.6-1 part, sodium hydroxide 1-3 parts, and pure water in remainder. The water-soluble protective ink has good adhesion to glass and is easy to remove, and the use of hot water for removal greatly reduces the complexity of the method, improves the production efficiency and implementation feasibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mobile phone back cover processing, and particularly relates to a front method for acid etching protection of a mobile phone back cover glass. BACKGROUND

[0002] Common materials of mobile phone back covers include plastic, metal, glass and ceramic, and 3D glass combined with AG sanding methods has been favored as a mobile phone back cover material in recent years. The AG sanding method is to process glass through chemical acid etching, and in the etching process, the other side (generally the concave surface of the 3D glass back cover) of the glass etching surface (generally the convex surface of the 3D glass back cover) is temporarily protected. Acid-resistant protective ink can effectively protect the covered parts during AG sanding due to its strong acid resistance. However, when spraying acid-resistant protective ink, ink dots often splatter onto the convex surface of the 3D glass back cover, causing the positions of these splattered ink dots to become defective points in the subsequent AG sanding process, thereby affecting the AG sanding effect.

[0003] CN106824705A discloses an ink spraying method for a 3D glass cover plate, the 3D glass cover plate comprising a plane part and a curved surface part, the main steps are: silk printing a peelable adhesive film on the outer side of the curved surface part; drying the peelable adhesive film; pasting a plane protective film on the outer side of the plane part of the 3D glass cover plate; pasting a VA area protective film on the visible area of the inner side of the 3D glass cover plate to form a pretreated glass cover plate; placing the pretreated glass cover plate on a workbench; spraying ink on the spraying area of the pretreated glass cover plate with a nozzle to form a pre-dried glass cover plate; heating the pre-dried glass cover plate to dry the ink layer; and tearing off the plane protective film, the VA area protective film and the peelable adhesive film on the 3D glass cover plate. The peelable adhesive film and the plane protective film protect the outer side of the 3D glass cover plate during the process of spraying ink, and the peelable adhesive film and the plane protective film can be torn off after the ink is dried to eliminate ink flying. The method effectively reduces the proportion of 3D glass cover plate defective products caused by ink flying, but the operation steps are extremely cumbersome. Although pasting a film is an effective choice, pasting a film will inevitably consume a large amount of labor, and considering that this step is a front protection for protecting the ink, pasting a film is not cost-effective. Considering the need to adapt to large-scale construction, it is appropriate to use spraying operation to realize temporary protection of the convex surface of the 3D glass rear cover. However, once spraying is involved, ink flying is inevitable, and at the same time, there are several problems that need to be overcome: first, the temporary protection of the convex surface of the 3D glass rear cover will not affect the subsequent AG sanding of the convex surface of the glass rear cover and the acid-resistant protective ink of the concave surface of the glass rear cover, that is, the ink splashing points generated when the temporary protection is formed on the convex surface of the 3D glass rear cover will also be under the protection of the acid-resistant ink, and will not cause additional defects; second, the scheme cannot be too cumbersome, and the operability needs to be improved, and it cannot affect the subsequent AG sanding of the convex surface of the glass rear cover and the acid-resistant protective ink of the concave surface of the glass rear cover, that is, the temporary protective coating of the convex surface of the 3D glass rear cover needs to be easily removed.

[0004] To this end, a front method for acid etching protection of a mobile phone rear cover glass is needed to improve the efficiency of acid etching of the mobile phone rear cover glass and the yield after acid etching. SUMMARY

[0005] The present application aims to provide a front method for acid etching protection of a mobile phone rear cover glass, which is simple to operate and realizes temporary protection of the convex surface of the 3D glass rear cover by using a temporary coating, and the temporary coating is easy to remove to improve operation efficiency.

[0006] To achieve the above-mentioned purpose, the present application provides a front method for acid etching protection of a mobile phone rear cover glass, the rear cover glass comprising a 3D glass concave surface and a 3D glass convex surface opposite thereto, the method comprising the following steps:

[0007] Step one, preparing a water-soluble protective ink;

[0008] Step two, first spray a layer of water-soluble protective ink on the convex surface of the 3D glass, and then spray acid-resistant protective ink on the concave surface of the 3D glass after the water-soluble protective ink is cured;

[0009] Step three, after the acid-resistant protective ink on the concave surface of the 3D glass is cured, remove the water-soluble protective ink on the convex surface of the 3D glass.

[0010] Preferably, the water-soluble protective ink comprises the following components by mass fraction of 100 parts: water-soluble acrylate oligomer 80-90 parts, wetting agent 0.1-0.5 parts, defoaming agent 1-2 parts, color paste 0.6-1 part, sodium hydroxide 1-3 parts, and pure water in the rest.

[0011] Preferably, the water-soluble acrylate oligomer comprises the following components and their mass fractions: acrylic acid 5-10 parts, methacrylic acid 10-20 parts, butyl acrylate 25-45 parts, azobisisobutyronitrile 0.6-1 part, ethanol 30-50 parts, and ammonia in an appropriate amount for adjusting the pH value of the water-soluble acrylate oligomer.

[0012] Further preferably, the preparation method of the water-soluble acrylate oligomer is as follows: add ethanol into a reaction kettle with condensation reflux, constant pressure dropping device, temperature display and stirring device, heat the ethanol to its reflux temperature, the reflux temperature is 85±5℃, after the reflux is stable, add the uniform mixture of acrylic acid, methacrylic acid, butyl acrylate and azobisisobutyronitrile into the reaction kettle in a broken bead shape, stabilize the temperature to 90℃, and keep the reaction for 4 hours to obtain an acrylate mixture, then cool the acrylate mixture to 60℃, add ammonia to neutralize to pH 8.0-9.0, and finally reduce the pressure to filter most of the ethanol to obtain the water-soluble acrylate oligomer.

[0013] Preferably, the wetting agent is one of polyethylene glycol or polyether organosilicon compounds.

[0014] Preferably, the defoaming agent is BYK-054.

[0015] Preferably, the color paste is water-based sapphire blue.

[0016] Preferably, the preparation steps of the water-soluble protective ink are as follows: add the corresponding amount of water-soluble acrylate oligomer, film forming agent, wetting agent, defoaming agent, color paste, sodium hydroxide and pure water into the container in sequence while stirring, and then stir until completely dispersed and uniform to obtain the water-soluble protective ink.

[0017] Preferably, the water-soluble protective ink removal method is to place the back cover glass in 90℃ hot water for 3-10 minutes to complete the ink removal.

[0018] The application provides a front-arranged method for acid-erosion protection of a mobile phone back cover glass, a layer of water-soluble protective ink is sprayed on the 3D glass convex surface of the mobile phone back cover glass, thereby reducing the adverse points caused by the splashing of acid-resistant protective ink to the 3D glass convex surface when the acid-resistant protective ink is sprayed, the overall method is simple and easy to implement, and the glass failure rate caused by the splashing of the acid-resistant protective ink can be greatly reduced. Meanwhile, the water-soluble protective ink has good adhesion to the glass, the water-soluble protective ink is sprayed before the acid-resistant protective ink, and no new adverse points are caused on the 3D glass concave surface, the water-soluble protective ink is easy to remove, the water-soluble protective ink can be removed by standing in hot water at a certain temperature, the complexity of the method is greatly reduced, and the production efficiency and implementation feasibility are improved. DETAILED DESCRIPTION

[0019] The embodiments described below are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0020] The application provides a front-arranged method for acid-erosion protection of a mobile phone back cover glass, the back cover glass comprises a 3D glass concave surface and a 3D glass convex surface opposite to the 3D glass concave surface, and the method comprises the following steps.

[0021] Step one, preparing water-soluble protective ink;

[0022] Step two, spraying a layer of water-soluble protective ink on the 3D glass convex surface, and spraying acid-resistant protective ink on the 3D glass concave surface after the water-soluble protective ink is solidified;

[0023] Step three, removing the water-soluble protective ink on the 3D glass convex surface after the acid-resistant protective ink on the 3D glass concave surface is solidified.

[0024] The water-soluble protective ink comprises the following components according to 100 parts by mass: 80-90 parts of water-soluble acrylic ester oligomer, 0.1-0.5 parts of wetting agent, 1-2 parts of defoaming agent, 0.6-1 part of color paste, 1-3 parts of sodium hydroxide, and the balance of pure water.

[0025] The composition and mass fraction of the water-soluble acrylate oligomer are as follows: 5-10 parts of acrylic acid, 10-20 parts of methacrylic acid, 25-45 parts of butyl acrylate, 0.6-1 part of azobisisobutyronitrile, 30-50 parts of ethanol, and an appropriate amount of ammonia for adjusting the pH value of the water-soluble acrylate oligomer. Acrylic acid and methacrylic acid have excellent compatibility with water, the former has stronger polarity, which can ensure the water solubility of the oligomer as a whole, butyl acrylate has strong reactivity and a relatively low glass transition temperature, and belongs to a soft monomer, which can balance the softness and hardness of acrylic acid and methacrylic acid and is closely related to the adhesion of the finally obtained oligomer. The reason for selecting azobisisobutyronitrile is that it can stably initiate the reaction within a certain temperature range.

[0026] The preparation method of the water-soluble acrylate oligomer is as follows: ethanol is added to a reaction kettle with a condensation reflux, constant pressure dropping device, temperature display and stirring device, the ethanol is heated to its reflux temperature, the reflux temperature is 85±5℃, after the reflux is stable, a uniform mixture of acrylic acid, methacrylic acid, butyl acrylate and azobisisobutyronitrile is added to the reaction kettle in a broken-bead manner, the temperature is stabilized to 90℃, and the reaction is kept for 4 hours to obtain an acrylate mixture, then the acrylate mixture is cooled to 60℃, ammonia is added for neutralization to a pH value of 8.0-9.0, and finally most of the ethanol is removed by vacuum filtration to obtain the water-soluble acrylate oligomer. The wetting agent is one of non-ionic fluorocarbon polymer compounds or polyether silicone compounds. An appropriate amount of wetting agent is added to improve the wetting and spreading properties of the ink on the substrate, prevent the occurrence of defects such as shrinkage and edge shrinkage, and too much wetting agent may have adverse effects on re-coating. The non-ionic fluorocarbon polymer compound can be mainly divided into four categories: polyethylene glycol type, sulfoxide type, polyol type and polyether type, and the polyethylene glycol type can be mainly selected, specifically PEG200 or PEG400. The polyether silicone compound is a polyether modified silicone surfactant, which is connected by chemical bonds. By adjusting the polymerization degree of polyether and silicone, silicone surfactants with different properties and different purposes can be obtained, which can be applied in the coating industry, polyurethane, pesticide and daily chemical industry, etc. Preferably, BYK-349 is selected.

[0027] The defoaming agent is BYK-054. The main function of the defoaming agent is to inhibit and eliminate the foam generated in the production and construction process of the ink. The non-silicon water-based defoaming agent is adopted in the present application. It should be noted that too little amount of the defoaming agent will have poor defoaming effect, and too much amount of the defoaming agent will cause problems such as shrinkage and poor re-coating.

[0028] The color paste is water-based blue, which can play a role in showing and observing the adhesion and removal of the water-soluble protective ink on the 3D glass convex surface.

[0029] The preparation steps of the water-soluble protective ink are: adding while stirring, adding corresponding amounts of water-soluble acrylate oligomer, film forming agent, wetting agent, defoaming agent, color paste, sodium hydroxide and pure water in the container in sequence, and stirring until completely dispersed and uniform to obtain the water-soluble protective ink.

[0030] The water-soluble protective ink removal method is to place the back cover glass in hot water at 90°C for 3-10 min to complete the ink removal. Example 1

[0031] The water-soluble protective ink provided in this embodiment includes the following components in parts by mass of 100: water-soluble acrylate oligomer 90 parts, wetting agent 0.2 parts, defoaming agent 1 part, color paste 0.8 parts, sodium hydroxide 1 part, and pure water 7 parts.

[0032] The preparation method of the water-soluble protective ink is: adding corresponding amounts of water-soluble acrylate oligomer, film forming agent, wetting agent, defoaming agent, color paste, sodium hydroxide and pure water in the container in sequence, adding while stirring, and stirring until completely dispersed and uniform to obtain the water-soluble protective ink.

[0033] The water-soluble protective ink is used in a front method for acid etching protection of a mobile phone back cover glass, and the method includes the following steps:

[0034] Step 1: preparing the above water-soluble protective ink;

[0035] Step 2: first spraying a layer of water-soluble protective ink on the convex surface of the 3D glass, and then spraying acid-resistant protective ink on the concave surface of the 3D glass after the water-soluble protective ink is solidified;

[0036] Step 3: removing the water-soluble protective ink on the convex surface of the 3D glass after the acid-resistant protective ink on the concave surface of the 3D glass is solidified. Example 2

[0037] The water-soluble protective ink provided in this embodiment includes the following components in parts by mass of 100: water-soluble acrylate oligomer 90 parts, wetting agent 0.2 parts, defoaming agent 1 part, color paste 0.8 parts, sodium hydroxide 3 parts, and pure water 5 parts.

[0038] The preparation method of the water-soluble protective ink is: adding corresponding amounts of water-soluble acrylate oligomer, film forming agent, wetting agent, defoaming agent, color paste, sodium hydroxide and pure water in the container in sequence, adding while stirring, and stirring until completely dispersed and uniform to obtain the water-soluble protective ink.

[0039] The water-soluble protective ink is used in a front method for acid etching protection of a mobile phone back cover glass, and the method includes the following steps:

[0040] Step one, preparing the above water-soluble protective ink;

[0041] Step two, first spraying a layer of water-soluble protective ink on the convex surface of the 3D glass, and then spraying acid-resistant protective ink on the concave surface of the 3D glass after the water-soluble protective ink is solidified;

[0042] Step three, after the acid-resistant protective ink on the concave surface of the 3D glass is solidified, hot water is used to remove the water-soluble protective ink on the convex surface of the 3D glass. Example 3

[0043] The present embodiment improves a kind of water-soluble protective ink, including the following components by mass fraction 100 parts: water-soluble acrylate oligomer 90 parts, wetting agent 0.2 parts, defoaming agent 2 parts, color paste 0.8 parts, sodium hydroxide 3 parts, pure water 4 parts.

[0044] The preparation method of the water-soluble protective ink is as follows: the corresponding amount of water-soluble acrylate oligomer, film-forming agent, wetting agent, defoaming agent, color paste, sodium hydroxide and pure water are added into the container in sequence, and the stirring is carried out while adding, until the complete dispersion is uniform, to obtain the water-soluble protective ink.

[0045] The water-based protective ink is used for a front method for acid etching protection of a mobile phone back cover glass, and the method includes the following steps:

[0046] Step one, preparing the above water-soluble protective ink;

[0047] Step two, first spraying a layer of water-soluble protective ink on the convex surface of the 3D glass, and then spraying acid-resistant protective ink on the concave surface of the 3D glass after the water-soluble protective ink is solidified;

[0048] Step three, after the acid-resistant protective ink on the concave surface of the 3D glass is solidified, hot water is used to remove the water-soluble protective ink on the convex surface of the 3D glass.

[0049] Comparative Example 1

[0050] The present comparative example provides a water-soluble protective ink, including the following components by mass fraction 100 parts: water-soluble acrylate oligomer 90 parts, wetting agent 0.2 parts, defoaming agent 0.5 parts, color paste 0.8 parts, sodium hydroxide 1 part, pure water 7.5 parts.

[0051] The preparation method of the water-soluble protective ink is as follows: the corresponding amount of water-soluble acrylate oligomer, film-forming agent, wetting agent, defoaming agent, color paste, sodium hydroxide and pure water are added into the container in sequence, and the stirring is carried out while adding, until the complete dispersion is uniform, to obtain the water-soluble protective ink.

[0052] The water-based protective ink is used for a front method for acid etching protection of a mobile phone back cover glass, and the method includes the following steps:

[0053] Step one, preparing the above water-soluble protective ink;

[0054] Step two, first spraying a layer of water-soluble protective ink on the convex surface of the 3D glass, and then spraying acid-resistant protective ink on the concave surface of the 3D glass after the water-soluble protective ink is cured;

[0055] Step three, removing the water-soluble protective ink on the convex surface of the 3D glass by hot water after the acid-resistant protective ink on the concave surface of the 3D glass is cured.

[0056] Comparative Example 2

[0057] The present comparative example provides a water-soluble protective ink, which comprises the following components by mass fraction of 100 parts: water-soluble acrylate oligomer 90 parts, wetting agent 0.2 parts, defoaming agent 1 part, color paste 0.8 parts, sodium hydroxide 6 parts, and pure water 7 parts.

[0058] The preparation method of the water-soluble protective ink is as follows: the corresponding amount of water-soluble acrylate oligomer, film-forming agent, wetting agent, defoaming agent, color paste, sodium hydroxide and pure water are added into a container in sequence, and the addition is carried out while stirring until complete dispersion and uniformity, thereby obtaining the water-soluble protective ink.

[0059] The water-based protective ink is used for a front method for acid etching protection of a mobile phone back cover glass, and the method comprises the following steps:

[0060] Step one, preparing the above water-soluble protective ink;

[0061] Step two, first spraying a layer of water-soluble protective ink on the convex surface of the 3D glass, and then spraying acid-resistant protective ink on the concave surface of the 3D glass after the water-soluble protective ink is cured;

[0062] Step three, removing the water-soluble protective ink on the convex surface of the 3D glass by hot water after the acid-resistant protective ink on the concave surface of the 3D glass is cured.

[0063] The water-soluble protective inks prepared in Comparative Examples 1 and 2 and Example 1-3 are detected, and the adhesion effect and removal effect of the water-soluble protective ink after being applied to the mobile phone back cover glass are tested. The test results are shown in Table 1:

[0064] Table 1 is the test data of the water-soluble protective ink in Example 1-3 and Comparative Examples 1 and 2

[0065] From the above data, we can see that the water-soluble protective ink prepared in Example 1-3 is clear and transparent, has moderate viscosity, good film-forming effect, good adhesion to the back cover glass of the mobile phone, short deinking time, easy removal, and no damage to the back cover glass of the mobile phone after deinking. From the test data of Comparative Example 1, it can be seen that too little amount of defoaming agent will affect the film-forming effect of the water-soluble protective ink on the back cover glass of the mobile phone, resulting in bubbles in the protective film affecting the film-forming effect. Although it does not affect the adhesion, the bubbles may increase the risk of penetration. From the test data of Comparative Example 2, it can be seen that too much sodium hydroxide will cause damage to the back cover glass of the mobile phone, so the amount needs to be strictly controlled. From the data of Example 1, Example 2 and Comparative Example 2, it can be seen that the addition of sodium hydroxide has a great influence on the hot water removal time of the water-soluble protective ink. Too little amount of sodium hydroxide will prolong the hot water deinking time, and too much amount of sodium hydroxide will greatly shorten the hot water deinking time, but will cause damage to the back cover glass of the mobile phone.

[0066] The above describes the present application in detail in combination with the embodiments. In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined and changed in any appropriate manner without contradiction, and the present application will not describe various possible combinations again. In addition, other modifications and combinations of each technical feature according to the present application should be considered as disclosed content of the present application, and all fall within the protection scope of the present application.

Claims

1. A pre-treatment method for acid etching protection of mobile phone back cover glass, wherein the back cover glass includes a 3D concave glass surface and an opposing 3D convex glass surface, characterized in that, The method includes the following steps: Step 1: Prepare water-soluble protective ink; Step 2: First, spray a layer of water-soluble protective ink onto the convex surface of the 3D glass. After the water-soluble protective ink has cured, spray an acid-resistant protective ink onto the concave surface of the 3D glass. Step 3: After the acid-resistant protective ink on the concave side of the 3D glass has cured, remove the water-soluble protective ink on the convex side of the 3D glass. The water-soluble protective ink, by weight, comprises the following components in 100 parts: 80-90 parts water-soluble acrylate oligomer, 0.1-0.5 parts wetting agent, 1-2 parts defoamer, 0.6-1 parts color paste, 1-3 parts sodium hydroxide, and the remainder being purified water. The preparation method of the water-soluble acrylate oligomer is as follows: ethanol is added to a reactor equipped with a reflux condenser, a constant pressure dripping device, a temperature display, and a stirring device. The ethanol is heated to its reflux temperature, which is 85±5℃. After the reflux stabilizes, a homogeneous mixture of acrylic acid, methacrylic acid, butyl acrylate, and azobisisobutyronitrile is added dropwise into the reactor in a bead-like manner. The temperature is stabilized at 90℃, and the reaction is maintained at this temperature for 4 hours to obtain an acrylate mixture. Then, the acrylate mixture is cooled to 60℃ and neutralized with ammonia water to a pH value of 8.0-9.

0. Finally, most of the ethanol is removed by vacuum filtration to obtain the water-soluble acrylate oligomer.

2. The pre-treatment method for acid etching protection of mobile phone back cover glass according to claim 1, characterized in that: The composition and mass fractions of the water-soluble acrylate oligomer are as follows: 5-10 parts acrylic acid, 10-20 parts methacrylic acid, 25-45 parts butyl acrylate, 0.6-1 part azobisisobutyronitrile, 30-50 parts ethanol, and an appropriate amount of ammonia to adjust the pH value of the water-soluble acrylate oligomer.

3. The pre-treatment method for acid etching protection of mobile phone back cover glass according to claim 1, characterized in that: The wetting agent is a nonionic fluorocarbon polymer compound or a polyether organosilicon compound.

4. The pre-treatment method for acid etching protection of mobile phone back cover glass according to claim 1, characterized in that: The defoamer is BYK-054.

5. The pre-treatment method for acid etching protection of mobile phone back cover glass according to claim 1, characterized in that: The pigment is water-based sapphire blue.

6. The pre-treatment method for acid etching protection of mobile phone back cover glass according to claim 1, characterized in that: The preparation steps of the water-soluble protective ink are as follows: while stirring, add the appropriate amount of water-soluble acrylate oligomer, film-forming agent, wetting agent, defoamer, color paste, sodium hydroxide and purified water to the container, and stir until completely dispersed and uniform to obtain the water-soluble protective ink.

7. The pre-treatment method for acid etching protection of mobile phone back cover glass according to claim 1, characterized in that: The method for removing water-soluble protective ink is to place the back cover glass in 90°C hot water for 3-10 minutes to complete the ink removal.