CN111793811A

CN111793811A - Method for decorating base material

Info

Publication number: CN111793811A
Application number: CN202010548791.7A
Authority: CN
Inventors: 劳淑如; 吴萌芽
Original assignee: Yongguang International Commodities Co ltd
Current assignee: Yongguang International Commodities Co ltd
Priority date: 2020-03-11
Filing date: 2020-06-16
Publication date: 2020-10-20

Abstract

The present invention relates to a method of producing a durable non-ferrous metal finish on a substrate. The method of the invention comprises the following steps: (a) carrying out first electroplating on the base material to form a first conductive metal layer on the surface of the base material; (b) carrying out first electrophoretic coating on the substrate subjected to the first electroplating to form a first coating layer on the first conductive metal layer; (c) applying a laser beam to the substrate subjected to the first electrophoretic coating to form a conductive area in the first coating layer; and (d) performing a second electroplating of the substrate to form a second conductive metal layer on the conductive region; and/or (e) carrying out second electrophoretic coating on the base material after the second electroplating to form a second coating layer on the second conductive metal layer or the conductive area. The decorative pattern produced by the present invention is of high quality, clear, well defined, with color and/or metallic finish. The method is applicable to flat, uneven, curved, uniform or non-uniform surfaces.

Description

Method for decorating base material

Technical Field

The present invention relates to a method of decorating a substrate; in particular, the present invention relates to a method of producing a durable non-ferrous metal finish on a substrate.

Background

Conventional methods for creating patterns with metallic surfaces on substrates include:

step 1: electroplating (Electroplating) and Electrocoating (Electroplating)

According to industry practice, the general process is to treat the substrate with electroplating and electrocoating processes, by which the exterior decoration of the product can be achieved.

Electroplating is a process of dissolving a metal onto a substrate surface using an electric current. Electrocoating is a process of depositing a coating, epoxy, or other aqueous solution onto the surface of a substrate, which may be performed after the substrate has been treated with an electroplating process.

Step 2: screen printing, pad printing and thermoprinting

Step 2 of the method is to print a complex pattern onto the outer surface of the substrate. Screen printing, pad printing and hot stamping processes are mutually exclusive processes, but can all be performed after electroplating and electrocoating processes.

Screen printing is a printing technique. In this technique, the mesh is used to transfer the ink to the substrate, except for the areas that are impermeable to the ink by closing the stencil; a blade or doctor is moved over the screen to fill the open mesh with ink, and then a reverse stroke causes the screen to momentarily contact the substrate along a line of contact, which causes the ink to wet the substrate and pull it out of the mesh as the screen springs back after the blade passes through. This process can only print one color at a time, thus requiring multiple screens to generate images or designs of multiple colors.

Pad printing is a printing technique. Pad printing can transfer 2D images to 3D substrates by an indirect offset (gravure) printing process, which involves transferring the image to the substrate through a silicone pad. Pad printing machines utilize 3 main components: a printing plate, an ink cup, and a pad to successfully transfer the printing plate to the substrate. Wherein, the printing plate is engraved with images; the ink cup will contain ink as it slides over the squeegee and leave a small amount of ink in the etch; a printing pad is a transport system in which a somewhat flexible silicone material is pressed against an ink filled etch to pick up an image and moved over a substrate, and then the substrate is pressed again to transfer the image.

Hot stamping or bronzing is a printing method of letterpress printing in which a predried ink or foil is transferred onto a surface at high temperature. In a hot stamping machine, a mold is installed and heated, and a product to be stamped is placed thereunder. A metalized or painted roller-leaf carrier (roll-leaf carrier) is inserted between the two and the mold is pressed down through it. The paint or foil used is embossed on the surface of the product. Since the material involved is dry, the dyeing process itself is pollution-free.

Conventional electroplating and electrocoating processes do not create any specific pattern on the substrate. For this purpose, the pattern must subsequently be printed onto the substrate.

When printing patterns on curved surfaces, the problem of high defect rates is found with conventional printing methods (screen printing, stamping and pad printing). When printing on curved, uneven and matte surfaces using these conventional printing methods, defects such as damage, breaks or discontinuous patterns often occur. Moreover, by these conventional methods, the patterns on the printed colored metal surfaces are often limited by the available coatings. In particular, when producing a gold-colored metallic finish, the conventional method uses real gold patches to adhere to the substrate, so printing a gold-colored metallic pattern is very expensive.

Disclosure of Invention

In view of the deficiencies of the prior art, it is an object of the present invention to provide a method of decorating a substrate on which a specific pattern is printed. The method of the present invention is applicable to surfaces that are flat, uneven, curved, uniform or non-uniform. The decorative pattern produced by the present invention is of high quality, clear, well defined, with color and/or metallic finish compared to conventional methods. The method also enables a high quality non-ferrous metal finish to be obtained at a lower cost. The pattern produced by the present method is durable, wear resistant and chemically resistant.

The invention adopts the following technical scheme:

a method of decorating a substrate comprising the steps of:

(a) carrying out first electroplating on the base material to form a first conductive metal layer on the surface of the base material;

(b) carrying out first electrophoretic coating on the substrate subjected to the first electroplating to form a first coating layer on the first conductive metal layer;

(c) applying a laser beam to the substrate subjected to the first electrophoretic coating to form a conductive area in the first coating layer; and

(d) carrying out secondary electroplating on the base material to form a second conductive metal layer on the conductive area; and/or

(e) And carrying out second electrophoretic coating on the substrate to form a second coating layer on the second conductive metal layer or the conductive area.

According to the solution of the present invention, step (d), step (c) or a combination thereof may be selected after step (c) according to the desired colour and/or metallic finish.

In some embodiments, a method of decorating a substrate comprises the steps of:

(d) and carrying out secondary electroplating on the substrate to form a second conductive metal layer on the conductive area.

In some embodiments, a method of decorating a substrate comprises the steps of:

(e) and carrying out second electrophoretic coating on the substrate to form a second coating layer on the conductive area.

In some embodiments, a method of decorating a substrate comprises the steps of:

(d) carrying out secondary electroplating on the base material to form a second conductive metal layer on the conductive area; and

(e) and carrying out second electrophoretic coating on the substrate to form a second coating layer on the second conductive metal layer.

In some embodiments, the method further comprises repeating steps (c) - (e), steps (c), (d) or steps (c), (e) one or more times, depending on the color and/or metallic finish of the desired pattern. The electroplating and electrocoating of the present invention are conventional operations in the art, and the conditions required for electroplating and electrocoating and the effects achieved are clear to those skilled in the art, so that those skilled in the art can repeat steps (c) to (e), steps (c) and (d) or steps (c) and (e) one or more times according to the specific operations to achieve the desired pattern decoration and color and/or metallic finish thereof.

In the technical solution of the present invention, the first conductive metal layer may include one or more metals. The metal in the first conductive metal layer of the present invention may be selected from conventional conductive metals known to those skilled in the art.

The conductive metal may be selected from copper, nickel, silver, platinum, or any combination thereof.

In some embodiments, the first conductive metal layer comprises copper, nickel, or a combination thereof.

In some embodiments, the first conductive metal layer comprises copper, nickel, silver, or any combination thereof.

In some embodiments, the first conductive metal layer comprises copper and nickel.

In some embodiments, the copper comprises acid copper, alkali copper, pyrocopper, or any combination thereof.

In some embodiments, the copper includes acid copper, alkali copper, and pyrocopper.

In some embodiments, the first coating layer is clear and/or colored.

In the technical scheme of the invention, after the base material is subjected to the first electrophoretic coating, the first coating layer is deposited on the surface of the first conductive metal layer to cover the conductive metal layer. And the first paint layer may be transparent or colored according to a desired color of the pattern. The electrophoretic coating of the coating layer of the present invention may be selected from conventional electrophoretic coatings well known to those skilled in the art.

In some embodiments, the electrocoat used in the first electrocoat is a composition known as EC-9236B, which comprises: cationic polyacrylic resins and isocyanates.

In this composition, a cationic polyacrylic resin is a main resin, and isocyanate is a curing agent. Polyacrylic resins can be neutralized with organic acids due to specific functional groups in the chemical structure and then dispersed in water to form an emulsion. Meanwhile, the solvent-based curing agent in the coating is dispersed into emulsion particles, so that isocyanate molecules are wrapped in the coating by the cationic polyacrylic resin molecules. The cationic polyacrylic resin and the wrapped isocyanate are dispersed in pure water in a cationic form to form the electrophoretic coating working solution. During electrophoresis, the cationic polyacrylic resin and the coated isocyanate move to a cathode and are coalesced on the surface of a coated object to form an electrophoresis wet film, and the electrophoresis wet film is cured at a temperature higher than 130 ℃ for a certain time to form a polyurethane dry film. The chemical composition of the dry film is Polyurethane (Polyurethane), and the molecular formula of the dry film is as follows: - [ -O-CONH- ] n-; the dry film can pass the ROHS test.

In some embodiments, the composition further comprises lactic acid, a co-solvent, and pure water.

In some embodiments, the percentage of cationic polyacrylic resin and isocyanate in the composition is 58-68%.

In some embodiments, the composition comprises the following components in weight percent:

in this composition, the content of lactic acid is low. The lactic acid is mainly used for adjusting the pH value of the electrophoretic coating working solution. When the content of lactic acid is insufficient, the pH value of the electrophoretic coating working solution is too high, and the electrophoretic coating film has the problems of yellowing, roughness, pinholes and the like; when the content of lactic acid is too high, the pH of the electrophoretic coating working solution is too low, the electrophoretic coating is not easy to paint, and meanwhile, the paint film re-dissolution degree is increased, and the painting is influenced.

In some embodiments, the co-solvent is an alcohol, an alcohol ether solvent, or a combination thereof.

The cosolvent can volatilize in the drying process of the coating film, so the cosolvent has no residue in the dry film. The co-solvent aids in coalescence of the electrocoat film upon deposition; but also to assist in leveling the electrophoretic wet film. Too low content of cosolvent can cause the problems of difficult coalescence of the coating film in the deposition process, rough surface of the formed coating film, pinholes and the like. Too high cosolvent content can cause the reduction of the electrophoretic permeability, and the electrophoretic wet film is easy to be stuck with foreign matters in the drying process.

In the composition, the pure water is used for reducing the viscosity of the electrophoretic coating stock solution, so that the composition is convenient to use; meanwhile, when the electrophoretic coating working solution is prepared, the stock solution is easy to disperse. The electrophoresis wet film contains moisture which can be volatilized after high temperature, so that no moisture is left in the dry film. One skilled in the art can adjust the components of the electrocoat composition and its content to achieve the desired coating layer effect.

After the electrodeposition coating process of the substrate, the surface-coated paint is cured and the surface of the conductive metal material is insulated.

In some embodiments, the laser beam in step (c) is emitted by a laser.

In some embodiments, the laser has a power of 20-50 watts and a frequency of 50-80 Hz.

In some embodiments, the laser has a power of 25-40 watts and a frequency of 55-70 Hz.

In some embodiments, the laser has a power of 30 watts and a frequency of 60 Hz.

In the technical scheme of the invention, the first paint layer corresponding to the pattern can be removed on the insulated surface according to the required pattern by using the laser beam. Complex but precise, sharp patterns can be produced by means of a laser beam. The laser irradiated areas/patterns will become conductive after the first paint layer is removed. It will be appreciated that the laser beam forms conductive areas corresponding to the desired pattern or portions of the pattern. The inventors are aware that the application of a laser beam to an electrocoated surface is not known in the art.

Through practice, the inventors of the present invention have found that applying a laser beam to an electrocoated surface to engrave/engrave a pattern can very effectively produce a well-defined pattern, and in conjunction with electroplating, can produce a metallic color pattern surface.

In the technical solution of the present invention, the second conductive metal layer may include one or more metals. The metal in the second conductive metal layer of the present invention may be selected from conventional conductive metals known to those skilled in the art.

In some embodiments, the second conductive metal layer comprises silver.

In the technical scheme of the invention, the second conductive metal layer is formed on the conductive area by electroplating the base material for the second time.

In some embodiments, the second coating layer is clear and/or colored.

In the technical scheme of the invention, after the base material is subjected to the second electrophoretic coating, the second coating layer is deposited on the second conductive metal layer, so that the required color and/or pattern of the metal veneer are realized.

In some embodiments, the step of applying a UV coating to the substrate is also included. The optional UV coating may act as a strong protective layer against chemical attack.

In the technical solution of the present invention, since the steps (c) to (e), steps (c), (d) or steps (c), (e) may be repeated one or more times according to the desired color and/or metal finish, the step of applying the UV paint is performed after achieving the desired technical effect.

A decorated substrate prepared according to the above method.

The method can be used for decorating the surfaces of different substrates, and therefore, the method has wide application in different products. The method can be used for any product needing decorative patterns, including logos, trademarks and aesthetic patterns. The method can be used to create aesthetic patterns on products that are flat, uneven, curved, uniform or non-uniform, such as bottles, perfume bottles, vases, picture frames, and the like.

Use of a decorated substrate in products where a pattern is to be created, these products having a flat, uneven, curved, uniform or non-uniform surface.

Compared with the related art, the conventional method for generating patterns on a substrate having a metal/colored surface mainly comprises the following steps: 1. electroplating-copper layer; 2. electroplating a nickel layer; 3. electrophoretic coating-a coating layer; 4. printing a required pattern: screen printing; or pad printing; or hot stamping; 5. and (5) coating a UV coating.

Wherein electroplating and electrocoating processes are known to those skilled in the art. The invention replaces the conventional screen printing, pad printing and hot stamping processes through the steps (c), (d) and (e).

As previously mentioned, color printed metal patterns by screen printing and pad printing are limited by the coatings available on the market. But the quality, accuracy and definition of the patterns produced by screen printing and pad printing are low and often have drawbacks. In printing on curved surfaces, defects of damage/breakage often occur in screen printing and pad printing. It has been found difficult to print lines around a continuous or precisely end-to-end circular cap. Despite the complexity of the pattern and color metal surface treatment requirements, the present method is capable of printing smooth, continuous, accurate, sharp patterns on flat, curved, and non-uniform surfaces. The method can also print patterns by using various colors according to requirements.

Stamping can achieve the desired metallic color, but this technique has the inherent weakness of leaving cracks in the metallic gold foil. This is due to the difference in the coefficients of thermal expansion of the intermediate coating and the foil. The hot stamping on uneven surfaces and complex patterns further exposes the weakness, so that the defect rate of the hot stamping process on the base material is very high.

The method of the present invention allows printing on non-uniform surfaces while also maintaining a low defect rate.

Compared with the traditional method, the method can lead the produced colorful metal facing to be smoother, clearer and more defined, and the decorative pattern is more accurate. The cost of the method is much lower especially for gold-colored metal surface treatment. In contrast to the present method, a metal surface treatment can be achieved despite conventional methods (e.g. stamping). But results in a high defect rate due to the inherent problems of stamping. Other methods do not achieve metal surface treatment or are too costly. The manufacturing costs of the present method are also much lower (e.g., for printing gold-colored metal finishes, the present method is at least three times less expensive than conventional methods).

This invention allows printing of patterns on substrates having uneven surfaces that have been treated by electroplating and electrocoating. The invention makes it possible to achieve a metal finish with high chemical resistance.

For substrates with uneven surfaces, printing thereon using electroplating and electrocoating processes is no longer limited by the complexity of the pattern.

The process of the invention obviously reduces the reject ratio of products.

The invention has the advantages of

(1) The process of the invention can be applied to metallic, smooth, reflective surfaces of any color; smoothness and light reflection are adjusted by a combination of a conductive metal layer and a paint layer, a change in thickness of the conductive metal layer or paint layer, a color of an electrophoretic paint, and a metal layer (e.g., silver layer) to produce metallic luster, which cannot be achieved by conventional screen printing and pad printing.

(2) The present invention precisely engraves a desired pattern on an electrophoretically coated substrate by means of a laser beam, thereby removing a corresponding first coating layer on the engraved surface. After removing the corresponding first paint layer, the underlying metal is exposed to electrodeposition for a further metal plating, and a further electrocoating is performed on the engraved areas. Therefore, the process of the invention is not affected by the complexity of the pattern, and the produced pattern is smooth, clear and well-defined.

(3) Because a plurality of materials with different thermal expansion coefficients are not adopted, the method eliminates the inherent defect rate caused by the hot stamping process, and the defect rate of products produced by the process is low.

(4) The pattern produced by the process is durable.

Drawings

FIG. 1 is a diagram of the effect of creating a pattern using a screen printing process;

FIG. 2 is a diagram illustrating the effect of using a pad printing process to generate a pattern;

FIG. 3 is an effect diagram of patterns generated by a hot stamping process;

FIG. 4 is a comparison graph of metallic luster effect of patterns produced by screen printing, pad printing, the process of the present invention, and hot stamping, respectively.

Detailed Description

The present invention will be described in detail below with reference to specific examples.

A method of decorating a substrate comprising the steps of:

(a) electroplating the substrate for the first time to form a first conductive metal layer on the surface of the substrate

The first conductive metal layer may include one or more metals. In one embodiment, the first conductive metal layer comprises copper and nickel; wherein a layer of copper is deposited on the substrate followed by a layer of nickel. In one embodiment, the copper is comprised of acid copper, alkali copper, and pyrocopper. A copper layer electroplated on the substrate for improving adhesion between the material layers. Nickel plated on a substrate, alloys of which also have valuable properties for providing elemental resistance, hardness and conductivity, due to the excellent wear resistance of nickel. Other metals may be selected for use in the present invention depending on the desired properties, as will be appreciated by those skilled in the art.

(b) Carrying out first electrophoretic coating on the substrate after the first electroplating to form a first coating layer on the first conductive metal layer

Electrocoating can provide a uniform coating layer on the substrate according to the desired color to achieve a smooth finish on the exterior of the substrate. In one embodiment, the first coating layer is transparent. In one embodiment, the first coating layer is colored. In one embodiment, the first coating layer is clear and colored. In one embodiment, the electrocoat used in the first electrocoat is EC-9236B. Other coatings for electrocoating may be used in the present invention, as will be appreciated by those skilled in the art, depending on the color of the desired pattern.

(c) Applying laser beam to the first electrophoretic coated substrate to form conductive region in the first coating layer

In this step, a portion of the insulating first paint layer corresponding to the desired area/pattern is removed from the substrate surface, and thus a conductive area is formed in the first paint layer. In one embodiment, the laser beam is emitted by a laser having a power of 30 watts and a frequency of 60 Hz. One skilled in the art can select different power and frequency combinations to achieve electrophoretic coating removal without damaging the underlying electroplated nickel layer.

(d) Performing a second electroplating on the substrate to form a second conductive metal layer on the conductive region

The second conductive metal layer may include one or more metals. In one embodiment, the second conductive metal layer comprises silver to achieve a surface with a metallic luster. As will be appreciated by those skilled in the art, the second conductive metal layer may comprise other metals, depending on the effect of the desired pattern.

(e) And carrying out second electrophoretic coating on the base material subjected to the second electroplating to form a second coating layer on the second conductive metal layer.

In one embodiment, the same gloss and metallic finish as the true metal is obtained by applying an electroplated silver layer and a clear yellow electrocoat. The present invention significantly reduces the cost of printing a gold-colored metal pattern by at least three times compared to using real gold. Other electrocoats for electrocoating may be used in the present invention, as will be appreciated by those skilled in the art, depending on the color of the metallic or non-metallic pattern desired.

In one embodiment, the method of decorating a substrate does not perform step (d) depending on the desired pattern effect. And (e) after the step (c), carrying out second electrophoretic coating on the substrate to form a second coating layer on the conductive area.

In one embodiment, the method of decorating a substrate is performed after step (c) and without step (e) according to the desired pattern effect.

In one embodiment, the method further comprises repeating steps (c) - (e) once, depending on the desired pattern effect.

In one embodiment, the method further comprises repeating steps (c) and (d) once, according to the desired pattern effect.

In one embodiment, the method further comprises repeating steps (c) and (e) once, depending on the desired pattern effect.

As understood by those skilled in the art, step (d), step (c), or a combination thereof may be selected after step (c) depending on the desired color and/or metallic finish; furthermore, steps (c) to (e), steps (c) and (d) or steps (c) and (e) may also be repeated one or more times.

In one embodiment, the method finally comprises the step of applying a UV coating to the substrate.

Examples of the experiments

Example 1

The method of the invention is adopted to process the zinc alloy parts, and the specific process flow is shown in table 1

TABLE 1

Comparative example 1

And (3) processing the zinc alloy parts with the same specification by using a conventional method and a screen printing process. The specific process is shown in table 2:

TABLE 2

The effect of generating a pattern of comparative example 1 is shown in fig. 1. Fig. 1 shows that the product of the screen printing process exhibits poor connection (left) and print leakage (right), in which the defective rate of poor connection is 90% and the defective rate of print leakage is 20%.

Comparative example 2

And (3) processing the zinc alloy parts with the same specification by using a conventional method and a pad printing process. The specific process is shown in table 3:

TABLE 3

The effect of generating a pattern of comparative example 2 is shown in fig. 2. Fig. 2 shows that the product of the pad printing process exhibited poor connection (left), uneven ink (center), and excess ink (right), where the defect rate of poor connection was 100%, the defect rate of uneven ink was 50%, and the defect rate of excess ink was 25%.

Comparative example 3

And (4) processing the zinc alloy parts with the same specification by using a conventional method and a hot stamping process. The specific process is shown in table 4:

TABLE 4

The effect of generating a pattern of comparative example 3 is shown in fig. 3. Fig. 3 shows that the product of the hot stamping process has poor connection (left) and ink loss (right), wherein the defect rate of the poor connection is 95% and the defect rate of the ink loss is 30%.

The comparison of the metallic luster effect of the patterns produced by the screen printing process, the pad printing process, the process of the invention and the hot stamping process is shown in fig. 4 (the screen printing process, the pad printing process, the process of the invention and the hot stamping process are respectively products produced from top to bottom), and it can be seen that the patterns produced by the process of the invention have obvious metallic luster. Although the hot stamping process can also produce obvious metallic luster, the overall quality of the pattern is far inferior to that produced by the process of the invention because the defect rate of the pattern produced by the hot stamping process is high.

The object of the invention is susceptible of numerous modifications and variants, all within the same inventive concept disclosed in the appended claims. All the parts may be replaced by other technically equivalent elements and the materials may differ as required, without departure from the scope of protection of the invention.

Although the object has been described with particular reference to the accompanying drawings, the drawings used in the description and the claims are only for the purpose of better understanding the invention and do not constitute any limitation to the scope of protection disclosed therein.

Claims

1. A method of decorating a substrate comprising the steps of:

2. A method of decorating a substrate according to claim 1 further comprising repeating steps (c) to (e), step (c), (d) or steps (c), (e) one or more times.

3. A method of decorating a substrate according to claim 1, wherein the first conductive metal layer comprises one or more metals, preferably copper, nickel or a combination thereof; the second conductive metal layer comprises one or more metals, preferably silver.

4. A method of decorating a substrate according to claims 1-3 wherein the electrocoat used in the first electrocoat is a composition comprising a cationic polyacrylic resin and an isocyanate.

5. A method of decorating a substrate according to claim 4 wherein the composition further comprises lactic acid, a co-solvent and pure water; wherein the cosolvent is an alcohol, an alcohol ether solvent or a combination thereof.

6. A method of decorating a substrate according to claim 1 or claim 2 wherein the laser beam in step (c) is emitted by a laser.

7. A method of decorating a substrate according to claim 1 wherein the first coating layer is clear and/or coloured; the second coating layer is clear and/or colored.

8. A method of decorating a substrate as claimed in claim 1 further comprising the step of applying a UV coating to the substrate.

9. A decorated substrate, characterized in that it is produced according to the method of any one of claims 1-3 or 6-8.

10. Use of the decorated substrate of claim 9 in a product where a pattern is desired.