Color Screen Printing Inscriptions, Signs, Paint Panels and Inks

With the color screen printing process, various types of substrates can be selected for panels, inscriptions, and signs, and the surface sprayed with amino-based coating is more of a kind because it has no special requirements on the substrate, especially the surface condition of the aluminum sheet. , Slightly plaque, light aluminum can use this method, greatly improving the utilization of aluminum, so domestic and foreign electronic equipment, instrumentation equipment, production of decorative panels, Ming, signs of the basic processing methods, in this process The method is described below.

First, color silk screen painting panel, Ming, signs of the process

Second, the main process description:

(1) Machining with painted panels shall be completed by mechanical finishing according to the appearance of the panel, the nameplate and the label, and the internal assembly requirements. Therefore, this method can be mass-produced, and the internal mounting dimensions and overall dimensions are consistent. Better, and at the same time, due to the first mechanical processing, it is very convenient to select a uniform positioning reference when overprinting, which brings great convenience to screen printing.

(2) Due to the poor combination of the aluminum substrate and the paint surface, the treatment of the aluminum substrate should be increased prior to the spray-coating. There are two methods of treatment, one is to spray a layer of epoxy zinc yellow primer with a thickness of about 0.01 millimeter after the substrate is degreasing; the other is to chemically oxidize the substrate to produce an aluminum oxide film and paint. Produce a strong bond.

Basic oxidizing liquid formula:

Potassium dichromate (K2CrO1) (Industrial) 4~5g/1

Chromium (CrO3) (Industrial) 5~7g/1

Sodium fluoride (NaF) (Chemical) o.8~1g/1

Phosphoric acid (H3PO4) (industrial) 10-15g/l

Temperature 15~35°C

Time 4~8min

(3) Topcoats can use common amino paints, 861 amino paints, or B8252 acrylic paints and H04-56 black amino paints. These paints have a certain degree of hardness and adhesion and are often used. The drying conditions are carried out according to the requirements of the paint type. For light paints, especially white paints, the drying temperature and time should be strictly controlled.

Before spraying the primer, if scratches are found on the surface of the substrate, a layer of putty should be scraped first. After the scratch is filled, the primer is sprayed. If chemical treatment is used, apply it before chemical treatment. The sandpaper grinds the scratches so that the surface of the workpiece is smooth and smooth.

(4) Screen Printing, Equipment and Process Requirements:

a, a reasonable choice of screen: fine pattern, character H ≤ 2.5 mm, should choose ≥ 350 mesh monofilament yellow PET mesh.

b. The thickness of the photosensitive layer on the screen template should not exceed 20 μm;

c. Mesh spacing According to the tension of the reticles and the size of the frame, the screen plate distance can be projected from the workpiece at the instant that the screen plate is scraped during screen printing.

d, screen printing color screen uniform selection of positioning benchmarks, special attention to overprinting;

e. Screen printing ink should be selected according to the requirements of the workpiece. Such as solvent resistance, abrasion resistance, weather resistance, etc., while also meeting the design requirements of the color. The Seiko 1300#, 1000# ink series, which is commonly used by Sanwa International, ensures the quality of the product.

f, the printing sequence, should be printed after the dark color printing light, so as to avoid dark stains after the printing of light colors, overprinting before the color to be dry non-stick net, sticky hands, you can print a color, all printed should be dry completely.

(5) In order to protect the pattern, characters, etc., the screen-printed and thoroughly dried workpiece is subjected to a finishing treatment. Cover treatment can choose H-type water-soluble acrylic paint or amino varnishes. For the workpiece is light-colored, such as a white surface, in order to prevent the white paint yellow, so you can use C, D, S, J cellulose acetate cover, so that the bottom of the white paint is not yellow, so that the color pattern is bright.

(6) Sometimes for needs, such as the panel on the equipment in the dark room does not require reflection, and some electronic products do not need to reflect the panel, Ming, standard system but instead show elegant and beautiful, therefore, paint panels, Ming The finish of the sign may be light or semi-bright. For this purpose, the finished product is required to be high when the screen is printed. Therefore, the use of these two kinds of ink is more convenient to remove, otherwise the ink is dry or semi-dry to rub back and forth, then the surface of the top coat that is rubbed will produce bright patches, which will affect the effect of surface consistency.

Third, ink use in the important tips:

This process uses Japan Seiko high-quality epoxy resin 1300 # and two-component 1000 # metal ink, because the use of these two inks. In addition to their high adhesion strength, they also have extremely high surface hardness and lightness, and at the same time resist scratching and cleaning of various chemical cleaners on the panel. Therefore, these two inks can coexist with topcoats on the faceplate, never Separation and shedding. However, these two inks must be used with the correct process to achieve the desired effect.

1, 1300 # ink screen printing features:

1) One-component thermosetting ink with a catalyst (precursor) preliminarily added to the ink during the manufacturing process. Its characteristic is the drying standard temperature after screen printing at 150°C, and the drying time and workpiece size, material and ink layer thickness. Relevant, large workpiece area, thick thickness, the drying time is long, under normal circumstances need ≥ 30 minutes of drying time; when the set temperature> 150 °C, the drying time can be shortened accordingly, drying temperature It may not be less than 150°C, otherwise it will appear:

a. Not fully dry, because the precuring agent does not reach a certain temperature, the curing effect is poor;

b. Not fully dried, poorly imprinted, or even not strong;

c. If it is not completely dried, the surface brightness will be poor, and it will not wear out, organic solvents will rub off;

2) It is found that when printing under the correct screen printing process conditions and the above quality problems occur after drying:

● Ink does not adjust the viscosity, under normal circumstances special solvent T--1000 (10:1 ~ 1.5 preparation);

● The storage period at high temperature greatly exceeds the effective period of ink agglomeration and poor dissolution;

● In the effective period of storage at room temperature, the ink is affected by the external air, and the catalytic performance of the precuring agent (catalyst) is reduced. At this time, a 1% catalyst 1300H should be added for adjustment and reuse.

3) Color printing should pay attention to each printing should be low temperature (such as 100 °C × 10 minutes) drying, as long as not sticky, the last color screen printing should be completely dried at >150 °C; stack color printing should also abide by this The rules, otherwise each color is baked to completely dry, there will be a lack of adhesion between layers. It is noteworthy that the screen printing color spray paint, surface printing plate on the previous version of the paint layer should reach less than 100% dry solid, otherwise the paint surface paint crystallization, affecting the color ink and baking paint firmly attached, when screen printing When the ink is dried after the last color, the lacquer layer of the face plate is completely dried.

4) If it is used for both electroplating, nameplate protection imprint, and permanent screen printing color decorative pattern ink, then the PH value of the electroplating solution should be >3, for example electroplated nickel of the non-colored pattern part on the screen printed color sign, Gold plating solution, its PH value = 3.8 ~ 4.6.

2. Screen printing features of bicomponent 1000# ink:

1) Before the use of the two-component ink is correct or not, it is decided to ensure the performance of the ink design. Therefore, the correct deployment of the two-component ink can ensure the quality requirements of the two-component ink after screen printing and must be taken seriously.

2) The correct proportion of Seiko 1000# two-component screen printing ink and curing agent is commonly used as the main agent 7: hardener 3, so that the ratio after screenprinting and curing can reach 3H, alcohol resistance, alkali resistance, and resistance to alcohol The winding is also good. Of course, the ratio of the main agent to the hardener can be adjusted according to the requirements of the workpiece as the main agent 6: hardener 4, the ink layer after screen printing can be particularly good, but the other two properties, especially alkali resistance is not good.

3) The important method of deployment: First, the main agent ink should be fully stirred before use, and the main agent ink and hardener must be mixed strictly in proportion to each other, and the mixture should be fully stirred and then matured for 10 minutes. Solvent T-1000 is adjusted to 10% to 20% to the viscosity suitable for screen printing. If you make mistakes in the order of deployment, it will affect the curing properties and various characteristics of the ink film.

4) The correctly formulated two-component ink generally requires more than 2 hours of contact drying at 20°C and hardening of more than 30 hours. With the increase of the storage time, the better the resistance, the natural drying method of the white paint panel, The treated PE and PP labels are more suitable. After the screen printing of metal parts, it can also be dried and cured at 80°C~120°C.

5) When screen printing the amino spray paint panel, please note that in order to ensure the adhesion of the ink to the paint surface, the paint panel is dried to dry before screen printing to prevent crystallization of the paint surface. After the color screen printing ink is at 120°C Under the dry solid state, the amino baking varnish is completely dried, which is the key to ensure that the two-component ink can be firmly attached to the high-hardness and brightness amino baking varnish surface.

The above two inks can also be directly screen printed on iron, aluminum, stainless steel signs, so as long as the above process operation, a must-have color screen printing of the Ming, signs, paint panel is presented in front of this kind of network The printing process has been successfully used on instruments, instruments and electronic equipment for maritime military products.

Reprinted from: the world of screen printing: Chen Shan