Method for coating transparent plastic products

An object of this invention is a method for coating transparent plastic products such as protective windows of mobile phones, wherein the method the scratchable surface of the plastic product is protected with hard-coating and the opposite surface of the plastic product is provided with a printing, such as a logo and/or text, upon which is provided a protective layer. The invention is also related to a product, e.g. the protective window of a mobile phone.

For example, Finnish patent FIl 17621 discloses a method for producing a protective window. The protective window is provided with a logo and the scratchable surface is protected with hard-coating. The protective windows are dislodged from the workpiece, after which they are attached in the cover of mobile phones.

This invention relates to a new method, which is characterized in that the plastic product is produced of a plate preform, which handling in the production of plastic products is performed from the processing location in the middle of the plate preform, such as a hole. The production method for plastic products according to the invention is more inexpensive than all the other known methods. Thus the handling of the plate preform from a working phase and a work place to another is performed without touching with hands to the base plate, whereby the plastic product and all coatings, which belong to the plastic product, will remain clean throughout the whole production and coating process and after that regardless of the number of the process phases. At the same time the method ensures the production of the nearest possible high quality of the end product. The production and coating process, as a whole, is from the beginning to the end - from the production of the plate preform to the packed product - also faster than the other known production and coating processes for protective windows, because the phases of the production process for protective windows are in chain. The examples of various embodiments of the invention are described in dependent claims of the patent claim set. The invention is described in the following with an example by citing the enclosed drawing, wherein

Figure 1 illustrates a plastic product according to one embodiment in an axonometric view,

Figure 2 illustrates a plastic product according to another embodiment in an axonometric view and

Figure 3 illustrates a disc preform 21, from which the plastic products are cut out.

The plastic products 3, 12 are produced, for example, by injection moulding with a sort of injection moulding equipment used for the production of CD/DVD discs and its further processing equipment. Plastic products can also be produced with another equipment, which enables the use of the method described in the patent FI-117621.

Figure 1. The top surface of the plastic product is hard-coated 2 by the "spin- coating" method, in which varnish spreads equally from the center point outwards due to the centrifugal force in a direction of the radius onto the whole surface of the disc 21 (Fig. 3). Functional coating 1, such as sol gel or nanotube structure-coating, is provided onto the hard-coating 2. A characteristic of this coating may be, for example, self cleaning, scratch free, reflection preventive, etc. Functional coating may also be hard diamond or sapphire surface provided by laser ablation. One or more printings 5, 6, for example by means of tampo or silk screen printing or laser printing is made onto the opposite side, i.e. the underside, of the plastic product 3. Logos, the name of companies or another information and background color can be made with printings. The same time with injection molding, diffractive surfaces, which may be reflection preventive or decorative hologram figures, can also be made onto the surface of the plastic product. By means of laser ablation and masking decorative metal surfaces, for example silver or gold colored frames around the protective window or metal colored logos and/or text, can be made onto the product. The last coatings may be "primer" i.e. prime color/varnish 8 and protective varnish layer 9.

Figure 2. The top surface of the plastic product 12 is hard-coated 1 1 by the "spin- coating" method. One printing 12, for example name/logo "PINT AVISION" with white pigment is made onto the opposite side of the plastic product. A printing 13 of blue pigment may be for the background color and in the same for prime color. The printings are protected with protective varnish 15. Figures 1 and 2 shows two extremes, where in Figure 1 there are several layers on both sides of the plastic product 3 and in Figure 2 there are only one layer above the plastic product 12 and three layers beneath the plastic product. Between said extremes are found numerous choices when the embodiments described in the patent claims are combined in a proper and desired way. Naturally, the end product

may also be comprised of two plastic products, with which have decorative surfaces inbetween and the outer surfaces are provided with protective coating. More than two plastic products can also be superimposed, three, four or five and various decorative surfaces in the middle layers, whereby stereoscopic and 3D effect is achieved.