The Innovative Process of Packaging Screen Printing Decoration (I)

Screen printing due to process adaptability, can be light pressure, thick film, coarse-grained ink printing, it is often used in various types of packaging printed in the decorative means. This article introduces several new types of packaging screen printing decoration technology.

Luminous printing

The ink used for luminous printing is a light-storing ink containing a luminous material. Luminescent inks are made from luminescent pigments, organic resins, organic solvents, and auxiliaries in certain proportions through special processing techniques.

1. Luminescent pigments (light-storing pigments)

A light-storing pigment is a long-lasting luminescent material, referred to as a long afterglow material, also known as a luminous material. This type of material has structural defects and impurity defects in the lattice of the crystals formed during the synthesis process. The luminescence caused by the material lattice defects is called self-excitation light, and the luminescence caused by impurity defects is called activation luminescence. The actual application of various types of light-emitting materials is mostly the latter.

The glow of luminous materials is based on the principle of photoluminescence. The excitation light source is generally sunlight and an artificial light source. It absorbs the excitation light energy and stores it. After the light excitation stops, the stored energy is slowly released in the form of light. come out. Absorb light → light → store → re-light, the process can be repeated indefinitely many times, and the repeated use process of charging, discharging, recharging, and re-discharging of the mobile phone battery is similar.

This luminescent material emits light in a dark environment without an external light source, and its light emission time is called afterglow time. Long afterglow materials with good properties, such as long-lasting phosphors of silicate systems with a variety of luminescent colors, have the best afterglow characteristics of rare earth-activated alkaline earth aluminates and can achieve more than 20 hours of afterglow emission.

2. Application of long afterglow materials

The long-lasting afterglow material covers a wide range of applications and its product types are various. The long afterglow material can be used to make light-emitting coatings, light-emitting inks, light-emitting plastics, light-emitting fibers, light-emitting paper, light-emitting glass, light-emitting ceramics, and light-emitting marble. Security emergency, transportation, construction and decoration. In the field of modern printing, it is suitable for the packaging and printing of high-end products such as official documents, securities, documents, and high-grade tobacco, alcohol, pharmaceuticals, and cosmetics.

3. Registration ink preparation

When preparing a light-storing ink, note the following points:

(1) The particle size of the light-storing pigment

The size of the light-storing pigment should be controlled at 45 to 65 μm so that a practical light-storing ink can be produced.

(2) Selection of Resin

Since the light-storing material is an alkaline substance, the color of the resin has an influence on the light-emitting brightness of the resin, so the following two points should be taken into account when selecting the resin.

1 should use colorless or light color, good transparency resin, varnish.

2 Neutral or slightly acidic resin, varnish should be used.

Resin varieties are epoxy resin (E440), polyurethane resin, amino varnish, polyester resin, acrylic resin, hydroxy acrylic resin, acrylic polyurethane varnish (two-component).

(3) Selection of varnish

Usually based on different substrates to choose different types of transparent varnish, such as printing materials for metal materials, metal varnish should be used, the substrate is PVC material, optional PVC varnish.

(4) Preparation method

1 Preparation of storage ink should use glass or enamel containers.

2 In order to evenly distribute the light-storage material, a high-speed stirring method may be used, but a grinding method may not be used.

3 The relative density of the light-storing material is between 3.6 and 4.1, and it is easy to sink when preparing the ink. The anti-precipitation agent can be added to the resin to increase the storage period of the light-storing ink. Domestic fumed silicas have No. 2 and No. 4 points, of which No. 4 is better.

(to be continued)

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