Screen printing 150 questions (28-33)

â–¼28. What should you watch out for when choosing a screen?

The front has already introduced several ways to choose the silk screen. However, the choice of silk screen is not a pure problem. In addition to considering the screen, various constraints related to the cost of the ink, the substrate, and the like are also considered. Grasp the selected method and pay attention to the relevant issues, select the appropriate screen can be handy. When selecting a screen, you should pay attention to the following aspects.

1 First, consider the difficulty of ink passing through the screen. Generally, consider more aspects in this regard. High-transparency inks for intermediate-tone inks, pigment particles are relatively fine, and the ratio of pigment particles to the pigment carrier is higher, and the ink passing property is better. This ink can also pass well when using a high-mesh screen; general plastics. The ink passability is better; special-purpose inks, inks with high pigment concentration, although fine particles, are relatively poor in passability.

2 If the surface of the substrate is rough, a lower mesh screen is generally used.

Such as leather, canvas, foam sheet, wood and other materials printed. Since the surface of the substrate is rough and the ink absorption is strong, a mesh with a lower mesh number is used to ensure that enough ink passes.

3 Select the screen according to the fineness of the original text line. Contrary to the above situation, high-mesh screens are generally selected for fine lines.
4 Select the screen to consider the cost, in the premise of meeting the printing requirements, try to use the lower price of the screen.

â–¼29. How to choose the screen according to the substrate?

In screen printing, there are a wide variety of substrates and the substrate materials have their own characteristics. Usually when the screen is selected, it can be selected according to the material of the substrate.

1 Fabric printing When the substrate material is a fiber fabric, such as clothes, scarves, ties, school bags, etc., thin mesh, nylon mesh or polyester mesh can be used.

2Paper Type Printing When the substrate material is paper type, such as printing, advertising painting, postcards, wallpaper, calendar, etc., you can choose thin web, thick web, nylon web, thin polyester web, multi-filament polyester Wire mesh, monofilament polyester mesh.

3 Printing of plastics, glass, ceramics, metal products, and wood products When the substrate materials are glassware, metal containers, wood, ceramics, plastic products, toys, etc., thick retanning mesh, monofilament nylon mesh, and thin polyester thread can be used. Net, thin

Roll net, stainless steel wire mesh.

4 Electronic device printing When the substrate material is a circuit board, such as: integrated circuits, semiconductor components, insulation fabrics, TV components, etc. Thick webs, monofilament nylon mesh or multifilament polyester mesh can be used.

â–¼30. Domestic screen old and new models and foreign wire mesh model is how to express it?

According to the specifications of the nylon and silk screen specifications issued by the national standard GB2014-80, the representation of the screen model is as follows:
JF: indicates that the nylon (JN) (or Nylon) square (F ANG) flat group
JP: Indicates PING choke.
JQ: Nylon yarn full hank organization.
JCQ19: It represents the nylon (QUAN) hank structure.
CQ: indicates the full hank structure of the silk.
CB: indicates the silk half-knit yarn organization.
CP: Indicates silk plain weave.
The old model of JF type screen is represented by SP.
JP-type screen old models are represented by NX.
The JCQ type screen 110 model is represented by GG.
J: The nylon (JIN) nylon (commonly known as nylon).
C: indicates a silkworm (CAN) wire.
Q: Indicates the full (QUAN) hank structure.
B: indicates half (BAN) hank structure.
P: Ping (PING) stranded tissue.
F: FANG flat organization.

The representation of the Swiss wire mesh specification is as follows:
S: Means "S" screen. Thin wire diameter and thin mesh, large mesh. Suitable for copying artwork and photographic screenings.
T: indicates a "T" type screen. The wire diameter is coarser than the S type, and the mesh is smaller than the S type. Suitable for the production of color blocks or lines composed of image or text screen printing plate.
HD: Indicates "HD" type screen. The diameter of the wire is the thickest, the mesh is the smallest, and the screen is the thickest. It is suitable for the production of thick-lined pattern screen printing plates.
Example: 77 T indicates 77 mesh T-type screen.
90 HD, said 90 mesh HD screen.

Japanese wire mesh specifications are as follows:
NP, SSP, SP, (GG.) mean enamel products, plain weave, and multifilament respectively.
No NO66-No66-S is a plain weave, woven monofilament of a nylon product.
No, NoS, TPM, TNP, TP are polyester products, plain weave, No, NoS, TPM are monofilament, TNP, TP are multifilament, TP is expressed as monofilament, and weft is multifilament.
#No indicates stainless steel mesh, plain weave, woven (single line).

â–¼31. What are the commonly used solvents for screen printing?

Solvents are mainly used in screen printing to adjust the viscosity of inks, regulate the drying speed of inks, and to clean screen printing plates and printing squeegees after printing. Commonly used solvents include aliphatic hydrocarbons, aromatic hydrocarbons, ketene, esters, ethanol, and glycol ethers. The solvents in each major category can be divided into several categories.

â–¼32 . There are several methods for coating the photosensitive liquid.

The coating method of the photosensitive liquid is divided according to the operation method and can be divided into two major categories of manual coating and mechanical coating. Each category can be further subdivided into several subcategories. Details are as follows:

Manual coating can be divided into the following methods depending on the tool used.

1 Brush with a lint-free brush.

2 Scrape with a thin plastic plate.

3 Scrape with a stainless steel blade.

4 cast coating method, also belongs to the hand-coated plate. The special feature is that instead of using the tool directly, the photosensitive adhesive is placed in a container, and the photosensitive adhesive is directly and continuously poured onto the vertically erected screen frame so that the photosensitive adhesive flows downwards automatically on the screen. Form a film. This plate making method is suitable for making special screen printing plates.

The above 1, 2, and 3 kinds of manual coating are more suitable for small-size screen printing plates, and the operation is simple.

Mechanical coating mainly refers to the application of a photosensitive liquid by mechanical action. Mechanical coating can be divided into semi-automatic and fully automatic coating (semi-automatic coating in addition to mechanical coating, but also need to manually assist the operation. Automatic coating is completed by the machine automatically). Mechanical coating is suitable for large area screen coating.

â–¼33. What is the significance of double exposure and how do you grasp the double exposure time?

In order to further improve the water resistance of the screen printing plates made after printing, the friction resistance, solvent resistance, and the strength and fastness of the screen printing plates are increased, and the printing resistance is improved. Usually, the double exposure method is used for yarns. The screen printing plate is hardened (in addition to the double exposure method, the screen printing plate is hardened by the drug). The second exposure time is usually determined according to the actual situation of the screen, including the selected screen, coating thickness and many other factors. The general secondary exposure time is one to three times the exposure time. `
Screen printing plates are hardened for high volume printing and disposable screen printing plates. Under what circumstances can the screen printing plate not be screen-hardened? First, the screen printing plate may not be hardened in a small batch printing. Secondly, in the case of preparing a release film after printing the screen printing plate and reusing the screen printing plate, the double-exposure hardening treatment cannot be performed, otherwise it would cause difficulty in film release.