A multi-color coating process for automotive door handles

Abstract

The application discloses a multi-color coating process for an automobile door handle, which comprises the following steps: S1, spraying a primer on the automobile door handle and drying; S2, spraying a water-based paint on the primer and drying; S3, using a cutting device to draw a seam along the edge to split the paint layer and tear any one side of the paint layer; S4, spraying an intermediate paint on the entire automobile door handle and drying; S5, stripping the water-based paint and the intermediate paint from the other side of the automobile door handle; and S6, spraying a top paint on the entire automobile door handle. The water-based paint in S2 is composed of the following components in parts by weight: 90-95 parts of a water-based polyurethane resin, 5-10 parts of a water-based additive and 2-5 parts of a chain extender. In the case that the water-based paint is between the primer and the intermediate paint, the water-based paint can be well stripped from the primer, the adhesion and the strippability are moderate, and the water-based paint plays a good intermediate conversion role; after the water-based paint layer is stripped, the adjacent double-color intermediate boundary line is neat and beautiful, and the paint layers are firmly engaged.

Description

Technical Field

[0001] This invention relates to an automotive painting process, and more particularly to a multi-color painting process for automotive door handles. Background Technology

[0002] After pretreatment and base coat application, car door handles require intermediate coats to be sprayed over certain sections of the base coat to create various colored stripes, thus achieving different stripe effects. To separate the two paint layers, a water-based paint layer is often added between them. For example, patent application number 201721808097.4 discloses a water-based peelable coating structure for automobiles, which involves spraying a modified water-based polyurethane primer onto the original paint layer for easy peeling and touch-up. This type of modified water-based paint layer is suitable for touch-up of individual paint layers but has poor mechanical properties, easily producing jagged edges during cutting. It is only suitable for peeling from a single sheet and not for mass production. Furthermore, in the automotive plastic parts painting industry, peelable water-based paints generally achieve moderate adhesion and peelability after reacting with a single paint surface, meeting the requirements for mass production. However, achieving moderate adhesion and peelability after reacting with multiple paint surfaces is very difficult. Summary of the Invention

[0003] The purpose of this invention is to provide a multi-color coating process for automotive door handles that can solve at least one of the above-mentioned problems.

[0004] According to one aspect of the present invention, a multi-color coating process for automotive door handles is provided, comprising the following steps:

[0005] S1. Apply primer to the car door handle and allow it to dry;

[0006] S2. Spray water-based paint over the primer and let it dry;

[0007] S3. Use a cutting device to cut along the edge seam of the paint layer and tear off any side of the peeling coating;

[0008] S4. Apply intermediate paint to the entire car door handle and allow it to dry.

[0009] S5. Peel the remaining water-based paint and intermediate paint from the primer on the other side of the car door handle.

[0010] S6. Apply topcoat to the entire car door handle;

[0011] S2 water-based paint is composed of the following components in parts by weight:

[0012] 90-95 parts of waterborne polyurethane resin, 5-10 parts of waterborne additives, and 2-5 parts of chain extender.

[0013] In some embodiments, the coating thickness formed by the water-based paint in S2 is 100~120μm.

[0014] In some embodiments, the chain extender is 3,3'-diethyl-4,4'-diaminodiphenylmethane.

[0015] In some embodiments, the primer comprises the following components in parts by weight:

[0016] The mixture contains 65-75 parts of hydroxyl acrylic resin, 10-20 parts of pigment, 1-5 parts of matting agent, and 10-15 parts of butyl acetate.

[0017] In some embodiments, the intermediate varnish comprises the following components in parts by weight:

[0018] The mixture contains 60-70 parts of hydroxyl acrylic resin, 5-10 parts of aluminum silver paste, 5-10 parts of ethyl acetate, 15-20 parts of butyl acetate, and 10-20 parts of pigment.

[0019] In some embodiments, the thickness of the primer coating is 10-15 μm, and the thickness of the intermediate coat coating is 8-10 μm.

[0020] The beneficial effects of this invention are:

[0021] By using the water-based paint of the present invention, the water-based paint can effectively separate from the primer when it is between the primer and intermediate paint layers, achieving a moderate level of adhesion and peelability, and playing a good intermediate transition role; after the water-based paint layer is peeled off, the boundary line between adjacent two colors is neat and beautiful, and the paint layers are firmly bonded together.

[0022] The water-based paint of this invention can meet the mass production requirements of multi-color coating process for automobile door handles. After the water-based paint layer is cut open by cutting equipment, it can be separated by mechanical equipment, which has good peelability.

[0023] By adopting the above steps, the accuracy of the boundary line of the two-color transition zone is ensured, avoiding the boundary color mixing, blurring and shadows that are easily caused by traditional spraying processes such as masking. This improves the stability of batch production of coating and reduces spraying defects. At the same time, it solves the quality defects caused by the unclear masking area formed by using plastic part fixtures for masking in the existing technology.

[0024] By adopting the above-mentioned formulation components, it can be applied to the mass production of automotive parts and automated spraying, resulting in a stable paint film thickness, uniform paint film surface, and good protection of the original paint surface. After the water-based paint layer is removed, the protected paint surface retains a good paint surface effect. Attached Figure Description

[0025] Figure 1 This is an image showing the effect of water-based paint peeling off from the primer in step S3 of a multi-color coating process for automotive door handles according to the present invention.

[0026] Figure 2 This is a diagram showing the effect of water-based paint and intermediate paint peeling off from the primer in step S5 of a multi-color coating process for automotive door handles according to the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings.

[0028] Example 1

[0029] The present invention provides a multi-color coating process for automotive door handles, comprising the following steps:

[0030] S1. Apply primer to the car door handle and allow it to dry;

[0031] S2. Spray water-based paint over the primer and let it dry;

[0032] S3. Use a cutting device to cut along the edge of the paint layer and peel off any side of the coating (e.g., Figure 1 (as shown)

[0033] S4. Apply intermediate paint to the entire car door handle and allow it to dry.

[0034] S5. Peel the remaining water-based paint and intermediate coat from the primer on the other side of the car door handle (e.g.) Figure 2 (as shown)

[0035] S6. Apply a topcoat to the entire car door handle. The topcoat can be a commonly used paint or clear coat applied to car door handles, which serves a protective function and enhances the gloss of the entire paint layer.

[0036] The primer in step S1, the water-based paint in step S2, the intermediate paint in step S4, and the topcoat in step S6 can all be applied automatically using spraying equipment, which facilitates the mass production of car door handles. The paint film thickness is stable and the paint film surface is uniform in each step.

[0037] S2 water-based paint is composed of the following components in parts by weight:

[0038] The product contains 925 parts of waterborne polyurethane resin, 8 parts of waterborne additives, and 3 parts of chain extender. The CAS No. of the waterborne polyurethane resin is 9009-54-5; the waterborne additive is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, CAS No. 77-68-9.

[0039] The coating thickness formed by the water-based paint in step S2 is 100~120μm.

[0040] The chain extender used is 3,3'-diethyl-4,4'-diaminodiphenylmethane, and its CAS No. is 19900-65-3.

[0041] Therefore, by using this water-based paint, when the water-based paint is sprayed onto the primer to form a film, in step S3, the water-based paint layer can be cut open by using a cutting device. During cutting, arbitrary cutting can be achieved without falling debris, with neat edges, no serrations, and clear edges. It is convenient to manually or mechanically peel off any side after cutting. During peeling, the primer is not affected, and the peeling performance is excellent.

[0042] In existing mass painting processes, masking fixtures are used to cover the side that does not need to be painted with the corresponding intermediate paint. After painting, the masking fixtures need to be cleaned and inspected repeatedly to avoid color interference. In addition, the masking fixtures are expensive to manufacture, time-consuming, and wear and tear during use. The high clamping accuracy of the masking fixtures makes it easy to produce defective products, resulting in high costs for mass production.

[0043] This invention, by employing this water-based paint and the aforementioned process steps, allows for spraying the entire car door handle during intermediate coat application without the need for masking, significantly improving production efficiency, making it suitable for mass production, and greatly reducing production costs. A comparison of the specific production efficiency of existing masking fixture-based spraying methods with the coating process of this invention can be found in the table below:

[0044] Process type Production efficiency (pieces / hour) Number of employees (personnel) Yield Traditional masking process 300 10 80% The coating process of this invention 2800 15 95%

[0045] Therefore, the multi-color coating process for automotive door handles of the present invention significantly improves production efficiency and yield when spraying automotive door handles. Traditional masking processes are inefficient, complex, and have low yields. Masking fixtures need to be assembled before spraying and disassembled afterward, requiring cleaning before reuse. Furthermore, traditional spraying processes such as masking are prone to defects such as edge mixing, blurring, and shadows. Although the present invention increases the number of workers, it makes the process more continuous, increasing production efficiency by 900%, while also improving the stability of mass production, reducing spraying defects, and solving quality defects caused by unclear masking areas in plastic parts fixtures, such as overspray, paint adhesion, and jagged edges.

[0046] After the various process steps of this invention, an intermediate coat can be applied to the primer layer on the side after step S3 where the water-based paint layer has been peeled off, thus forming a color different from the primer. On the side after step S5, since the intermediate coat and water-based paint are peeled off together, the primer color is retained, resulting in a multi-color coating effect for the car door handle. In practical use, the painting of car door handles or other automotive parts can be customized to meet different color requirements, satisfying multi-color painting needs.

[0047] The primer comprises the following components in parts by weight:

[0048] 70 parts hydroxyl acrylic resin, 20 parts pigment, 3 parts matting agent and 12 parts butyl acetate.

[0049] In practical use, the pigments in the primer can be adjusted according to the actual color requirements. For example, when using a black primer, the pigments consist of nano black paste and nano green paste, resulting in a good gloss effect for the black primer. The CAS No. of the nano black paste is 1333-86-4, and the CAS No. of the nano green paste is 1328-53-6; the composition is 15 parts nano black paste and 5 parts nano green paste.

[0050] By using this primer, water-based paint can form a certain degree of adhesion after being sprayed onto the primer, and at the same time, it has corresponding peelability. When the water-based paint layer is peeled off from the primer, the primer will not peel off along with it, thus ensuring the stability of the paint layer.

[0051] The intermediate paint comprises the following components in parts by weight:

[0052] The composition comprises 65 parts hydroxyl acrylic resin, 8 parts aluminum silver paste, 8 parts ethyl acetate, 18 parts butyl acetate, and 12 parts pigment. The pigment can be nano-blue paste, which, when mixed with the aluminum silver paste, creates a matte titanium silver color effect to meet specific requirements; or it can be a dark black mid-coat, specifically, the pigment can be nano-black paste, nano-blue paste, and nano-yellow paste to achieve the dark black color effect, with 10 parts nano-black paste, and 1 part each of nano-blue paste and nano-yellow paste. The CAS No. of the nano-blue paste is 57455-37-5, the CAS No. of the nano-black paste is 1333-86-4, and the CAS No. of the nano-yellow paste is 2783-94-0.

[0053] By using this intermediate paint, one side can bond well to the primer; at the same time, when the other side is covered on the water-based paint layer, it can bond with the water-based paint, making it easy for the subsequent water-based paint, along with the intermediate paint on that side, to separate from the primer on the corresponding side.

[0054] The primer forms a coating thickness of 10-15 μm, and the intermediate coat forms a coating thickness of 8-10 μm. Therefore, when each paint layer reaches its corresponding thickness, it exhibits excellent coverage, mechanical properties, and, for water-based paints, appropriate peelability.

[0055] The mechanical properties and peelability of each paint layer obtained by the multi-color coating process for automotive door handles of the present invention are compared with those obtained using conventional water-based paints, as detailed in the table below:

[0056] project Corresponding paint layer bonding Mechanical properties peelability The paint layer of the present invention Water-based paint is applied over the primer. It can be cut into any shape without leaving any debris, and the edges are neat and free of jagged edges. Can be peeled manually or mechanically. Existing process for spray coating Water-based paint is applied over the primer. The cut edges are serrated. Manual peeling yield is less than 70%, and mechanical peeling is not possible. The paint layer of the present invention Intermediate paint is applied over water-based paint. It can be cut into any shape without leaving any debris, and the edges are neat and free of jagged edges. Can be peeled manually or mechanically. Existing process for spray paint layer Intermediate paint is applied over water-based paint. The cut edges are jagged, and there are loose fragments. Manual peeling yields less than 50% success rate; mechanical peeling is not feasible.

[0057] Therefore, it can be seen that the multi-color coating process for car door handles of the present invention, based on its applicability to mass production and automated spraying of automotive parts, forms a stable paint film thickness, a uniform paint film surface, provides good protection for the original paint surface, and has excellent mechanical properties and peelability.

[0058] Example 2

[0059] The multi-color coating process for car door handles in this embodiment is basically the same as that in the previous embodiment, and the achieved effect is also the same. The difference is:

[0060] S2 water-based paint is composed of the following components in parts by weight:

[0061] 90 parts of waterborne polyurethane resin, 5 parts of waterborne additives, and 2 parts of chain extender.

[0062] The primer comprises the following components in parts by weight:

[0063] The composition consists of 65 parts hydroxyl acrylic resin, 15 parts pigment, 1 part matting agent, and 10 parts butyl acetate; among the pigments, there are 12 parts nano black paste and 3 parts nano green paste.

[0064] The intermediate paint comprises the following components in parts by weight:

[0065] The mixture contains 60 parts hydroxyl acrylic resin, 5 parts aluminum silver paste, 5 parts ethyl acetate, 15 parts butyl acetate, and 10 parts pigment. The pigment can be nano black paste, nano blue paste, and nano yellow paste to achieve the color effect of dark black. The nano black paste is 8 parts, and the nano blue paste and nano yellow paste are 1 part each.

[0066] Example 3

[0067] The multi-color coating process for car door handles in this embodiment is basically the same as that in the previous embodiment, and the achieved effect is also the same. The difference is:

[0068] S2 water-based paint is composed of the following components in parts by weight:

[0069] 95 parts of waterborne polyurethane resin, 10 parts of waterborne additives, and 5 parts of chain extender.

[0070] The primer comprises the following components in parts by weight:

[0071] The composition consists of 75 parts hydroxyl acrylic resin, 10 parts pigment, 5 parts matting agent, and 15 parts butyl acetate; among the pigments, there are 8 parts nano black paste and 2 parts nano green paste.

[0072] The intermediate paint comprises the following components in parts by weight:

[0073] The mixture consists of 70 parts hydroxyl acrylic resin, 10 parts aluminum silver paste, 10 parts ethyl acetate, 20 parts butyl acetate, and 20 parts pigment. The pigment can be nano black paste, nano blue paste, and nano yellow paste to achieve a dark black color effect. The nano black paste consists of 12 parts, and the nano blue paste and nano yellow paste each consist of 4 parts.

[0074] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A multi-color coating process for automotive door handles, characterized in that, Includes the following steps: S1. Apply primer to the car door handle and allow it to dry; S2. Spray water-based paint over the primer and let it dry; S3. Use a cutting device to cut along the edge seam of the paint layer and tear off any side of the peeling coating; S4. Apply intermediate paint to the entire car door handle and allow it to dry. S5. Peel the remaining water-based paint and intermediate paint from the primer on the other side of the car door handle. S6. Apply topcoat to the entire car door handle; The water-based paint in S2 is composed of the following components in parts by weight: 90-95 parts of waterborne polyurethane resin, 5-10 parts of waterborne additives and 2-5 parts of chain extender; The thickness of the coating formed by the water-based paint in S2 is 100~120μm; The chain extender is 3,3'-diethyl-4,4'-diaminodiphenylmethane; The primer comprises the following components in parts by weight: 65-75 parts of hydroxyl acrylic resin, 10-20 parts of pigment, 1-5 parts of matting agent and 10-15 parts of butyl acetate; The intermediate paint comprises the following components in parts by weight: The mixture contains 60-70 parts of hydroxyl acrylic resin, 5-10 parts of aluminum silver paste, 5-10 parts of ethyl acetate, 15-20 parts of butyl acetate, and 10-20 parts of pigment.

2. The multi-color coating process for automotive door handles according to claim 1, characterized in that, The thickness of the primer coating is 10~15μm, and the thickness of the intermediate coat coating is 8~10μm.

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