Fabrics, paper, leather, plastics, and various kinds of packaging boxes, etc., have a bump pattern and an exquisite pattern that are made by the method of roller compaction. In today's continuous improvement and improvement of people's living standards, the pressure roller mold also indirectly plays a role in embellishing life and beautifying life. With the advancement of science and technology and the continuous emergence of new materials, the graphic manufacturing technology of the press roll mold has also been developed and improved.
The pressure roller mold is mainly composed of the pressure roller body and the surface pattern. Here, I will focus on several manufacturing methods for the surface roughness pattern of the pressure roller mold (Figure 1 is the pressure roller blank):
1 hand carving
Figure 1 Press roll blank
Hand-carving method is commonly used in the 50-60s. It does not use any chemicals, no pollution, and is suitable for single-piece production. The production efficiency is low.
...... Blank Manufacturing â†’ Surface Drawing (Transfer) â†’ Manual Engraving â†’ Quenching â†’ Polishing...
The manual engraving method is to transfer the drawing pattern to the surface of the blank firstly by means of transfer or re-rotation, and then to sculpt according to this pattern, and finally to quench. The purpose of the quenching is to increase the hardness and wear resistance of the pattern surface of the pressure roller. Sex.
Roller graphic engraving is done by the craftsmanship and tools of the workers. Engraving workers, based on their skills acquired over many years of apprenticeship and after accumulating experience in long-term work, forged and abraded dozens of different types of tweezers of different widths and angles as tools for carving. When carving, small hammers are hit with a small hammer, and the small scorpions use the strokes and outlines of the patterns to remove the recessed parts little by little. The fine lines or the words with more complicated strokes must also be used. Fine prototype. Then sculpt to the required depth, flatten the concave bottom with flat chisels of different sizes, and finally repair the sharp or very thin corners with a small tweezers. So the pattern of a pressure roller is completed, in order to increase the hardness and wear resistance of the surface should also be quenched (also called heat treatment, is to increase the hardness of the metal without increasing the thickness of the metal surface), in order to reduce the surface Burrs also need to be polished (polishing treatment should be carried out before the quenching process).
Manual carving consumes a lot of energy, labor intensity is strong and is a kind of work with strong craftsmanship, and it is completely taught by the master teacher with an apprentice. However, with the advancement of time and technological advancement, the number of talents possessing such carving techniques is gradually decreasing, and fewer and fewer manufacturers use the engraving method to manufacture pressure roller patterns.
2 Chemical etching
This method is a more common method. Its advantage is that the cycle is short and it is convenient for mass production. Due to the application of photosensitized chemistry, the finer and more precise patterns can be produced than the engraving method, and the pattern manufacturing technology of the press roll mold has taken another step forward.
2.1 Asphalt-based etching
This method is suitable for the production of simple, repetitive, regular lines and full version of the dots and other graphics.
Blank Manufacturing â†’ Quenching â†’ Polishing â†’ Coated Bitumen â†’ Design Graphics â†’ Etching â†’ Asphalt Removal â†’ Cleaning
2.1.1 Preparation of Asphalt
Industrial Asphalt 200g
Toluene (or Solvent Gasoline) 200g
Rosin is first dissolved in toluene contained in a glass bottle. After complete dissolution, place the bitumen into small pieces, gently shake the bottle or stir to completely dissolve it.
1 Keep away from fire when preparing;
2 Prepare in a ventilated area;
3 The prepared bitumen is put into a small glass bottle, the bottle cap is tightened, and the solvent is used to prevent volatilization;
4 Adjust the dilute thick asphalt with toluene or solvent gasoline.
2.1.2 Coating of Asphalt
Brush the asphalt with a plate brush evenly on the surface of the pressure roller (the surface of the pressure roller should be cleaned before coating). Toluene or solvent oxime oil volatilizes quickly, it is best to apply at one go, if coated for the second time, the surface will be uneven.
It is to cut the surface of the asphalt to completely expose the metal.
Drawing method: The pressure roller is stuck on the lathe and spiraled on the surface. Finally, several equally divided horizontal lines intersect with the spiral line, so that the surface of the pressing roller forms a number of repeated â€œwellâ€ characters. After etching, a number of small protrusions spread over the entire surface of the press roll.
Can not use the turning tool when biting the asphalt, usually homemade needles, such as Figure 2, clipped on the chuck or with self-made spring knife, as shown in Figure 3.
Figure 2 homemade stylus
Fig. 3 Switch knife
The earliest etching method was to coat the surface of the press roll with an etchant, and from time to time (changing the position of the etching), the etching liquid was evenly etched to every part of the surface of the press roll. This method is slow and labor-intensive. At the same time, harmful gases from the etching process affect the health of workers. The current etching method is to immerse the surface of the press roll in an etching bath, a transmission press roll spindle, and then start the motor so that the press roll rotation speed is 10-15 rpm so that every part of the roll surface can be made Uniform etching can be obtained.
Figure 4 Etching or Development
2.2 Etching Method Using Photosensitive Film (Glue) as a Mask
2.2.1 Using Protein Gel as Photomask
This method is based on the water soluble protein tablets after adding ammonium dichromate sensitizer, and then the auxiliary mask - on the red powder, and finally etching. The most prominent advantage of this method is that the pattern can be etched deeply, but the process is cumbersome, the processes are numerous, the cycle is long, and the labor intensity is large, and it is not suitable for mass production.
...... rough manufacturing â†’ quenching â†’ photoresist coating â†’ exposure â†’ roller ink â†’ red powder â†’ development â†’ baking â†’ etching â†’ film removal â†’ cleaning.
1 Photosensitive adhesive preparation:
Protein tablets 50g
Ammonium Dichromate 5g
Water 700-900 ml
2 red powder preparation
Plate Red Powder 80g
Above, we used a mortar to grind over 300 mesh sieves.
3 Coat the photoresist: In the dark or in the yellow light, refer to Figure 5 when applying. At the leading edge of the squeegee, a double-layered 250-mesh screen was attached, and the stencil was about 2-3 mm ahead of the squeegee.
The squeegee is sloping in the same way as the direct stencil squeegee. The difference is that the pressure roller is rotated so that the photosensitive adhesive can be evenly applied to the surface of the pressure roller and finally dried under hot air.
Fig. 5 Rotary coating (photosensitive ink)
4 Exposure: Should choose cold light source, halogen series lamps, such as iodine lamp, high pressure mercury lamp, power should be more than 2kW, the exposure method is similar to the coating method, also the pressure roller is fixed on a bracket, adjust well Light source distance, then turn the pressure roller as shown in Figure 6. The compression of the backsheet is very important. The method of compaction can be made by scotch tape bonding and compaction, or a self-made polyester or plastic pouch can be pressed by vacuum. When applying the film, be sure to pay attention to the end to end of the film, positioning accuracy.
Figure 6 Exposure
5 roller ink on the red powder: first with a roller to print the ink on the prepared rubber platform (plating a layer of rubber) and then the pressure roller on the rubber platform rolling, the ink on the platform is applied to the pressure Roll surface. Finally, apply a layer of red powder to the surface of the pressure roller.
6 Development: Under the tumble underwater development, you can also use the water gun to wash the development (note the pressure control).
7 Baking: Bake in a 100Â° oven for 30 minutes to melt the ink and red rosin.
8 Etching: Refer to Figure 4 for the etching method.
9 times repeated: Roll ink on the red powder, development, baking, etching four processes. The purpose of repeating the four processes is to protect the etched side surface from being effectively dissolved by the red powder of the ink, so that the direction of the etching is more vertical to the bottom and the side etching is reduced. Therefore, the deeper pattern can be obtained than other methods, and the deformability is small (ie, the lateral corrosion is small).
10 to the film: use a brush to dip the gasoline brush to the surface of ink and red powder, and finally rinse with hot water.
2.2.2 Masking with bone glue and polyvinyl alcohol
This type of mask is suitable for etching less deep and relatively simple, rough graphics. Because the acid resistance of these two masks is somewhat limited (the corrosion resistance of the etching solutions of the nitric acid type and the sulfuric acid type is poor), the above two kinds of photosensitive masks use dichromic acid as a sensitizer, so they are not used in use. Six price emissions, pollution of water sources and the environment. It's just different in the formulation.
Preparation of bone glue photosensitive mask:
100-200g bone glue
Ammonium dichromate 5-10g
Polyvinyl alcohol photosensitive mask preparation:
Polyvinyl alcohol (degree of polymerization 1200) 100-200g
Ammonium dichromate 8-12g
PVA is put into water and boiled for more than one hour. It is completely dissolved by adding ammonium dichromate. Finally, a sufficient amount of water is filtered through a mesh of 350 mesh.
The process flow is:
Press roll blank manufacturing â†’ Quenching and surface cleaning â†’ Coating sensible â†’ Drying â†’ Exposure â†’ Developing and coloring â†’ High temperature polymerization â†’ Etching â†’ Removing film â†’ Cleaning the surface.
Most of the process flow is the same as the photoreceptor mask. The difference is: 1. It uses the film as a direct resist film. 2 Colorize directly after development to show the contrast of the graphics. 3High-temperature polymerization refers to: baking in an oven at 250Â°C for about 1 hour after development to make the purple mask golden yellow. The principle is: The simplest and common principle is explained as follows: Cr+6â†’Cr under ultraviolet light +3 forms a water-insoluble net-like chelate in the form of a coordination bond with (OH) in the adjacent PVA long chain and remains on the plate surface. However, the constant light part was washed out by water, so Cr+6 continued to exist in the form of Cr+6 pollution. There is also an explanation that: Passivation of UV and thermal energy causes (OH) dehydration to occur a condensation reaction, and the ether-type composition of the photobridges is left on the plate surface. No matter what theories are used to explain it, it will discharge Cr+6 and cause pollution. This is the main drawback of this mask.
2.2.3 Photoresist inks as masks
This mask is currently the most widely used one, its advantages are: simple operation, corrosion resistance