Photosensitive adhesive and photosensitive film for screen printing (3)

Liquid A: PVA(1788) 50g

Sodium dodecyl sulfate 0.5g

Water 400ml

Solution B: Ammonium dichromate 6g

Water 50ml

Sodium dodecyl sulfate is a dispersant in the formulation. The degree of polymerization of PVA is 1200 to 1700, and the degree of saponification is 88%, which can take into account the strength of the plate and the development performance.

Compared with gelatin, this glue is easy to plate, and the quality of the film is also improved. The disadvantages are low resolution, poor water resistance, and high humidity.

3PVA+PVAC photosensitive adhesive formula

A solution: PVA (1788) 40g

Sodium dodecyl sulfate 0.5g

Glacial acetic acid 4.0ml

Water 250ml

Solution B: Ammonium dichromate 5g

Water 30ml

PVAC emulsion 40ml

A small amount of red

The glacial acetic acid in the formulation can accelerate the dissolution of PVA and improve the development; the addition of PVAC emulsion can increase the adhesive force and water resistance of the plate. This glue is characterized by a certain increase in a variety of resistance.

Dichromate photosensitive adhesive is a kind of screen printing photosensitive adhesive which has been used for a long time and has been widely used. The photosensitive adhesive has the following characteristics;

Spectral light sensitivity between 370 ~ 530mm;

Photosensitive film layer can be photosensitized in proportion;

Any type of light source can be used for printing;

Exposure time is relatively short;

The price is cheaper.

The disadvantages of dichromated photoresists are:

The resolution is relatively low, and the outline of the graphic is easy to appear jagged.

Due to the influence of temperature and humidity, the stability of photosensitive emulsion is poor;

Low film strength and short service life

The screen printing plate coated with sensitized adhesive cannot be stored for a long time;

Heavy chromium contains a certain amount of toxicity, has some pollution to the environment and is harmful to the human body.

2. Nylon emulsion. Nylon emulsion adhesive is alcohol-soluble photosensitive adhesive, and its composition is:

Binary or trihydric alcohol-soluble nylon 100 parts

Acrylamide and bisacrylamide monomers 30 to 40 parts

Benzophenone (photoinitiator) 3 to 4 parts

Heat stabilizer 0.1 to 0.2 parts

A small amount of dyes and additives

The colloidal photohardening mechanism is similar to that of the iron salt photosensitive emulsion, that is, through the bulk polymerization of two propylene amine monomers, and the nylon is enveloped in the bulk structure.

Domestic nylon sensitized adhesives are available in both single- and dry-glue versions. The outstanding advantages of using nylon to dissolve nylon film are good strength, water resistance, and solvent resistance; the number of prints can exceed 100,000, which is particularly suitable for long-lived and water-based printing. material. The disadvantage is ethanol development, film removal is difficult, clarity is not too high.