Gradient mainstream scheme:

At present, there are four mainstream gradient color schemes: dyeing gradient scheme, color band transfer printing scheme, four color printing gradient scheme, and spraying gradient scheme. Processes such as PVD coating and ribbon transfer are difficult to control in terms of process requirements and costs, making mass production very difficult at present. On the contrary, if spraying process is used, equipment operation is simple, efficiency is high, and mass production is easier to achieve. It is understood that plastic shell models such as Huawei and OPPO may adopt gradient spraying.
In this fast-paced consumer era, appearance control is also a very important feature. 2018 is known as the explosive period of gradient colors. In order to reflect the decorative effect, even the mid-range mobile phone market has tried gradient colors. Therefore, it is worth exploring how to do a good job of gradient colors on the mainstream plastic back cover of the thousand yuan phone. Today, let's take a look at the gradient spraying process. Traditional spraying processes generally use single color spraying, so how is multi color gradient achieved through spraying? How to ensure the film thickness performance of its product?

Gradient spraying process

Spraying is a method of atomizing paint through a spray gun and applying it to the surface of an object for processing. Obtaining coatings with wear resistance, corrosion resistance, thermal insulation, conductivity, insulation, sealing, lubrication, and other special mechanical physical and chemical properties on the substrate belongs to traditional processes. The hardening treatment of plastic shells is achieved through spraying processes.
Gradient spraying is an innovation in the original spraying process. The main coating used is paint, which is applied to the surface of the product through spraying equipment. The mechanical operation is controlled by program mode to make the transition between different colors uniform. One, two or more colors of paint can be sprayed simultaneously, forming a natural transition effect between the two colors, ultimately achieving a gradient effect similar to that formed by PVD coating processing.
During the spraying process, the product is overlaid with multiple layers of colors (3-4 layers), with the core of controlling the thickness of the coating. Each layer gradually transitions from one color to another. In addition, the selection of coatings is also crucial. The selected coatings not only have wear resistance, corrosion resistance, and other properties for the surface substrate of the plastic shell, but also need to have a decorative effect on the exterior. The brightness effect of the color is also important.

Analysis of the current situation of gradient color spraying

This process has been verified by sampling on the cover plate of mobile phones, and the effect is similar to PVD coating and heat transfer printing. Moreover, this process is simple to operate, low in cost, fast in adjustment, high in work efficiency, fast in production, and easy to mass produce. Due to the upgrade of spraying to exterior decoration technology, the appearance inspection requirements after spraying are upgraded to A-grade surface. In the condition where the technology is not yet fully mature, the selection of coating, program control, spraying speed, and equipment selection will all affect the final spraying effect.
The gradient color automatic spraying machine utilizes program mode to control the mechanical operation, making the transition between different colors uniform. It can spray one, two or more color coatings simultaneously, forming a natural transition effect between the two colors. In the mainstream of mid to low end plastic shells, for the exterior decoration process, which can achieve both appearance effects and save costs, the better choice will be the spraying process. Samsung, Huawei, OPPO, and vivo are also developing new plastic shell processes (composite sheet, IMT injection molding, PC injection molding) for mobile phones. Gradual spraying may also become a trend in the mobile phone market in the near future.