德语
1. Principle of mold corrosion skin texture process
This process uses corrosion-resistant transfer ink to screen-print decorative patterns on decorative paper, and transfers the decorative patterns onto the mold by filming. After drying and trimming, chemical corrosion is performed to make concave and convex decorative patterns on the mold.
2. Process flow
Basemap production → photo-plate making → screen making → ink mixing → decal paper printing decorative patterns → ink drying → mold pretreatment → decal transfer → drying → trimming → corrosion → inspection → cleaning and rust prevention.
3. Process of decorative mold
01, base map production
Except for computer or hand-painted decorative patterns, most of them use plastic samples and artificial leather decorative patterns.
Plastic samples should be made with clear, uniform and flat surfaces. First spray a layer of black self-drying paint. After drying, apply it with more than 200 mesh white powder (calcium carbonate) to fill in the plain lines, and then gently wipe off the white powder on the protruding surface to expose it black until the layout is clear and black and white is clearly distinguished, and the base picture is completed.
If artificial leather decorative patterns are used, the artificial leather can be flattened and nailed on the wooden board, and the same processing is performed according to the above requirements. It is best to use black artificial leather to save spraying.
02, photo-made
Use CR or SO soft film to shoot the base image 1:1. The size of the photographic negative is about 100mm×200mm, which is easy to make screen plates and decal transfers.
03, wire mesh version
It is made of 200-300 mesh yellow polyester silk, a 0.02mm thick blue photosensitive film, an aluminum frame and a photographic negative film, and is manufactured according to the method of manufacturing a printed circuit screen plate.
04, Ink Mixing
Select 500g of high-quality solid asphalt, put it in a clean rust-free iron can, add 300ml of kerosene, and place it on an adjustable electric furnace for 1 to 2 hours. Control the slightly boiling state, stir appropriately, and refine it to a consistency suitable for screen printing. It is best to cool to room temperature and be soft and freeze on the surface without crust or wrinkle. This is asphalt ink.
Asphalt ink and 2711-4 ink (product of Tianjin Ink Factory) are mixed at a weight ratio of 1:1, then add Peony No78 drying oil, and the amount is 2% to 5% of the weight of the mixed ink. Mix it evenly with an ink knife to obtain an erosion-resistant transfer ink.
05, decorative paper printing decorative pattern
Use a WPS400 screen printing machine, install a screen plate, and place an appropriate amount of anti-erosion transfer ink on the rubber scraper. First, use the waste blueprint paper to interview the interview. The force should be even, light, and moderate, and do not return the ink until even and clear decorative patterns are printed, and then printed with decal paper.
The decal paper should be cut to an appropriate size before printing and scraped flat with a clean rubber scraper. If ink clogs the mesh during printing and the pattern is not clear, it means that the ink is too dry. You can add an appropriate amount of kerosene to dilute it;
If the printed decorative patterns are prone to blur, it means that there is too much kerosene in the ink. You can place the ink on the glass plate, mix it repeatedly with an ink knife, and then print the volatile part of the kerosene.
06, Ink drying
Put the printed decal paper on the oven grid, spread the ink side up, evenly, and do not overlap, control the temperature by 40-45℃, and bake until the ink is semi-dry, then remove it. That is, touch the ink on the decal paper without sticking to your hands, and sticking to your hands with a little pressure. Generally, bake for about 10-15 minutes. The ink is too dry and does not stick to the mold during transfer or has poor bonding strength; the ink is too moist and the transfer is easy to blur.
07, mold pretreatment
This process should be done before printing the decorative patterns on the decorative paper.
The surface roughness of the decorative pattern on the mold should be above the above, and there should be no sand holes or scratches to ensure that the decorative pattern is complete, clear and consistent. If the requirements are not met, additional grinding should be performed.
Use recycled wire dipped in gasoline to scrub the mold cavity and surrounding areas to make the surface clean. The surface without decorative patterns should be protected with nitrocellulose paint or perchlorethylene paint, and the paint should be applied two to three times. The holes and grooves can be protected with rubber plugs, plasticine, and sealing tapes.
After the paint film is completely dry, use magnesium oxide water slurry to degrease and clean the surface of the decorative pattern until the surface can be completely wetted by water. Then, use a sponge to soak up the water and blow dry with a hair dryer.
08, decal transfer
According to the characteristics of the mold cavity, cut the decal paper into a shape that is easy to stick. Gently peel off a layer of thin paper with decorative patterns. The ink faces the mold and paste it carefully. It must be smooth and conformable without wrinkles. Use a rubber scraper to scrape the flat surface and knead the curved surface into a ball with absorbent cotton. Press the paper base vertically to transfer the ink on the decal paper to the mold.
After the transfer is completed, use a sponge with a small amount of water to moisten the decal paper, then gently peel off the paper base, and use a sponge or absorbent paper to absorb the water on the mold.
09, dry
The ink transferred to the mold can be dried naturally in summer, but needs to be dried with infrared lamps in winter, and the surface and inside must be completely dry.
10. Trim
For the joints of decal transfers and defective decorative patterns, use a No. 0 or No. 1 pen dipped in transfer ink to repair them. After repairing, use an infrared lamp to dry them, and then use a pen-type trimming knife to trim excess ink until the decorative patterns are even and clear, and the connection is natural.
11. Corrosion
(1) Formula of corrosive liquid
Ferric chloride 450～560g/L
Hydrochloric acid 5～10ml/L
10~15 drops of kerosene/trough
The concentration of corrosive liquid should be controlled at 36~40°Be.
(2) Preparation before corrosion
Before the mold is corroded, magnesium oxide slurry should be used to degrease and clean the decorative pattern, and then tap water should be sprayed with a water gun for 1 minute to check whether the ink and the mold are firmly combined.
Then use a wool brush dipped in corrosive liquid to brush it over. The areas without ink should be uniformly gray and completely wetted with water to ensure uniform corrosion. During the above operation, if any ink falls off, the corrosion should be stopped immediately, and the decal transfer should be started again.
Under normal operating conditions, the ink and the mold are very tightly combined. The reason for detachment is improper operation. For example, when the decal is transferred, the mold is wet and does not dry, or the ink on the decal transfer paper is too dry, or there is no scraping after the decal is transferred. Pay attention during operation.
(3)Corrosion
After confirming that the mold can corrode, three layers of double-sided self-adhesive paper and polyvinyl chloride plastic cloth are used around the cavity to form a corrosion protection apron, which is 400 to 600mm longer than the mold. The corrosion machine adopts a nozzle-type spherical nozzle, with 19 nozzles evenly distributed in half of the sphere, which can spray evenly and three-dimensionally.
Use an electric hoist to hang the mold with the cavity facing down, the nozzle facing up and in the center of the protective apron. Two people hold the mold and rotate it slowly, start the etching machine, and use a stopwatch to time the corrosion for 7 to 10 minutes. In summer, lower the upper limit and in winter, lower the upper limit.
For molds that have specific requirements for the depth of decorative pattern corrosion, the same type of steel should be used as decorative pattern corrosion samples and the required time should be measured.
12. Inspection
Lift out the mold, rinse it quickly with tap water, stamp the decorative pattern with a 5-10x magnifying glass or plasticine, and check the corrosion depth. If the corrosion depth is not enough, it can be lifted back to supplement the corrosion. When the requirements are met, the tank will be cleaned immediately.
13. Cleaning and rust prevention
Rinse the mold with tap water, wash away the residual ferric chloride, remove the plastic apron, dry the surface with waste silk, peel off the sealing tape and perchlorethylene paint, wipe off the nitrocellulose paint with banana water, and wipe off the ink with gasoline. After cleaning, use a hair dryer to dry the mold, and then use recycled silk dipped in anti-rust oil to smear the surface of the mold.
4. Process characteristics
(1) Using self-prepared ink, it has the advantages of good corrosion resistance, strong adhesion, natural drying, and good transfer performance;
(2) Using a self-made spherical corrosion nozzle, the corrosive liquid can be sprayed into a uniform hemispherical surface, which is suitable for complex cavity corrosion. In addition, with the cavity facing downwards, the corrosive liquid will not accumulate, and a uniform corrosion depth, no corners, clear patterns, and high-quality decorative patterns can be obtained;
(3) The process method is simple and easy to operate, suitable for large, medium and small molds, and is not limited by geometric shapes;
(4) The equipment is simple and consumes very little material. It mainly consumes decal paper, transfer ink, and protective paint. It has low cost and high economic benefits.
Note: All pictures in the article are reprinted online, and will be deleted if infringed!
