Analysis of the Selection of Ink Additives in Printing

1. Curing ink binders can not only use a photo-curable resin, most of them use two or more photo-setting resins for assembly. The selection of light-curing materials depends on the object to be used, the construction method, and the nature of the coating film. The acrylic resin unsaturated polyester as the ink's main link material is the best. This resin has a very high ultraviolet light reactivity, can generate a hard light film, has the appropriate flexibility, can meet the needs of UV light solid printing .

2. The choice of pigment

Pigment selection requirements are:

1 The mixability of the pigment is better, and the UV curable ink will not be gelled during the effective storage period after compounding;

2 When the pigments are used together, the amount of each pigment in the photocurable ink must be accurate;

3 The pigment has high concentration, bright color, excellent dispersibility and sufficient coloring power;

4 Select pigments with low UV absorption, so as not to affect the curing speed of the photo-curable ink;

5 Do not discolor when the pigment is exposed to ultraviolet light or during curing reactions.

The absorption and reflectance of different pigments for the ultraviolet spectrum are different. Therefore, the curing speed of the photo-curable inks may also differ due to the different pigments. The pigments with good transparency have high UV transmittance and fast fixing speed; carbon black has higher UV absorption capacity and the slowest curing; white pigments have strong light reflectivity and affect curing. According to the above principles, the pigments used in UV drying inks are mainly titanium dioxide, benzidine yellow, phthalocyanine blue, permanent red, pink, red, sun-resistant dark red, carbon black, etc., as the main raw materials.

3. Photopolymerization initiator selection

When a photopolymerization initiator is added, if a part of the photopolymerization initiator has been added to the photo-curable resin, an appropriate amount of the photo-polymerization initiator should be added according to the difference in the pigment design. Generally, there are two methods for adding a photopolymerization initiator: First, a small amount of a photopolymerization initiator is added to the photo-curable binder, and a part of the photopolymerization initiator is added. Second, no photopolymerization is initiated in the photo-curing binder. Agent, add ink again.

4. Auxiliary agent selection

Wax is often used as an auxiliary agent in the ink to improve the abrasion resistance of the ink and reduce the viscosity. The basic requirements for ink waxes are high melting point, microcrystalline, such as microcrystalline waxes and polyethylene waxes. In addition, a small amount of tertiary amines, phosphine derivatives, and the like are added.