Inkjet printing organic pigment ink (6)

4.4 Preparation of Inkjet Printing Inks

4.4. l Preparation of pigment dispersion

A dry pigment or pigment paste or filter cake is first made into a pigment suspension, and the pigment is dispersed in water under high speed stirring at a concentration of 5%-20%.

The polymer dispersant was added with triethanolamine, an organic co-solvent isopropanol and an alkalizing agent, which was heated and dissolved in water at a temperature higher than the melting point of the polymer dispersant. For example, ACLYN 285A produced by A illed Signal Company of USA has a melting point of 85°C [24] and is fully dissolved in water.

The pigment suspension is also heated to this temperature, stirring is continued, the polymer dispersant is added, the temperature is maintained above the softening point, the low dry melting point is 10[deg.] C., and the dispersant is evenly distributed on the surface of the pigment over a time of about 20-30 in. The pH is often maintained at 8-10. The pigment dispersion is then cooled to about room temperature (25-30[deg.] C.) and stirring is still continued. The cooled polymer dispersant has been applied to the pigment surface and sanded to a particle size of less than 100 nm.

4.4.2 Preparation of ink

The pigment dispersion is added to the following mixed solution:

Phenylacetonitrile resin emulsion (water-soluble resin), diethylene glycol (humectant), anionic surfactant + nonionic surfactant (reduced surface tension of ink), disodium hydrogen phosphate (pH modifier), maltol ( Viscosity modifiers, anti-mold agents, etc., and then mixed thoroughly with water and mixed to obtain ink-jet printing ink.

5 Resin Adhesives

As with conventional paint printing, dry pigments do not have any binding force on the fibers, and the pigments must be mechanically combined with the fibers through adhesives to achieve the purpose of printing. However, the frequently used polyacrylate adhesives have far less film-forming properties and rheological properties than ink jet printing ink systems. The resin adhesives currently studied are generally of the ultraviolet curable type and polymeric microemulsion type. The former is to make monomers or oligomers and pigments of synthetic adhesives (such as polyurethane) into a low-viscosity ink that is sprayed onto the printed fabric and then cured by ultraviolet light to form a film; the latter is Adhesive components A pre-formulated polymer aqueous microemulsion, containing 30% to 50% solids, which is deposited on fabrics after inkjet and baking on fabrics, with particle sizes mostly below 1 μm.

5.1 UV curable adhesives [4]

The molecular weight of these adhesives should be smaller, and their monomers or oligomers and other chemicals are sprayed onto the fabric together with the pigments, dried and polymerized to form a film, and the pigments are firmly adhered to the fabric. Its advantages are fast curing, energy saving, no pollution, tight bonding between pigment and fiber, and high abrasion fastness. However, there are two problems: First, rapid polymerization tends to result in dense, rigid polymers with high fractions and relatively high degree of cross-linking. Such high scores will affect the fabric feel; the second is to use. Is the monomer or oligomer, the viscosity of the printing ink made will still exceed the basic needs of inkjet printing. The solution to the above problem is to add a large amount of diluent vinyl acetate to the polymerization system, which can make the polymer have longer flexible segments, thereby reducing its viscosity. The components (parts) with the low polymerization degree of polyurethane (polyurethane) as the main formula are as follows:

Carbamate diacrylate 24

Tetrahydroxyethyl diacrylate 8

Vinyl acetate (diluent) 48

Conductivity regulators 2

Photoinitiator 3

Cosolvent Acetone 15

The use of solvent-based dyes as pigments for such resin binder ink systems allows the pigments to penetrate deep into the binder polymer formed on the surface of the fibers during the UV light drying process. The maximum pigment concentration is within 10%. The following examples are UV curable adhesives and C.1. Solvent Blue 70 ink system performance:

Viscosity, mPa·s 36

Surface tension, m N/m 25

Conductivity, Siemens/cm 800

Glass transition temperature (Tg), °C -5