Three-dimensional printing process characteristics

The feature of three-dimensional printing is that the pattern of the printed fabric has an intriguing three-dimensional effect and is resistant to washing and rubbing.

The three-dimensional printing printing method and the used process and equipment are similar to general coating printing. The main difference is that the printing paste contains a microcapsule formulation or a foaming agent. Therefore, the pattern can quickly swell and bulge during the post-print heat treatment to form a gorgeous appearance. The three-dimensional shape. There are various types of three-dimensional printing, which are well known for fleece printing and foam printing. The foaming technology of the two is very different from the three-dimensional pattern formed. Under microscope observation, the surface of the piled print was filled with numerous tiny soap bubble-like ball shapes, and the foamed print was in the form of a bee cake. Therefore, the fleece printing product has a unique velvet embroidering effect, and the foam printing product has a vivid embossing effect.

The printing paste for fleece printing consists of a microcapsule formulation, a binder, a cross-linking agent, urea, a coating, a thickener or water. The microcapsules are small hollow spheres with a particle size of approximately 50/μm. The wall is composed of a copolymer of vinylidene chloride and acrylonitrile (approximately 2:1), while the capsule core contains a low boiling point, such as petroleum ether. Organic solvents. The microcapsules are dispersed in an emulsion such as polymethacrylic acid. The above solvent quickly vaporizes at a high temperature, just like blowing a soap bubble, so that the volume of the microcapsules expands, and the enlarged microcapsules are pressed together, so that a fluffy overlapping distribution is formed. Therefore, this foaming method belongs to physical foaming.

Typically, a polybutyl acrylate-based emulsion, or an acrylate and butyl acrylate copolymer, or a methyl methacrylate, methyl acrylate, and acrylamide copolymer emulsion is used as a binder for fleece printing. If you want to improve the rigidity of the three-dimensional printing pattern, ethyl acrylate and styrene copolymer emulsion can be used. If necessary, cross-linking agents can also be added. The amount of paint should not be too much. Otherwise, after the microcapsules are swollen, the coating material accumulated between the microcapsules has adverse effects on the nap feeling.

Net screen printing between 27.6 and 35.4 mesh/cm (70 to 90 mesh) is most suitable for fleece printing. After printing, 70 °C or so drying, 100-140 °C with hot air, hot plate, heat roller or infrared lamp and other heat source heat treatment 30 60s. The hot air blown fabric printed surface is the best. In order to prevent impeding the expansion, it is advisable to contact the heat source with the back of the fabric when foaming with a hot plate or a hot roll. The shortcomings of fleece printed fabrics are: they cannot be ironed after washing, otherwise, the microcapsules disappear and the velvet effect is lost. This kind of fabric is also easy to stain. The remedy is to add a coating agent.

Foaming printing agent is a kind of foaming agent mixed with the appropriate film former, cross-linking agent, emulsifying paste and coloring agent, and printed on the fabric. After the printing, the foaming agent undergoes thermal decomposition during the high-temperature treatment, so that a large amount of gas is generated, the film-forming agent is slightly expanded and filmed, and the gas released from the blowing agent is contained in the film, so that a novelty is formed. Three-dimensional pattern. This foam printing belongs to chemical foaming.

The commonly used blowing agent is called azodicarbonamide. It is a pale yellow crystalline powder that is insoluble in water. 64% of its decomposition products are solids and 36% are gases, while gases consist of nitrogen, carbon monoxide and carbon dioxide. The addition of urea, depending on the amount of urea, can reduce the decomposition temperature of azodicarbonamide from 200°C to 180°C or even 150°C. Azobisisobutyronitrile is a white crystal that is insoluble in water and can also be used as a foaming agent. Its decomposition temperature is only 90-115°C. However, the use of tetramethyl succinonitrile, which is toxic in its decomposition products, is limited. Foam printing pastes generally consist of polystyrene, methyl methacrylate, butyl acrylate and acrylamide copolymer emulsions, azodicarbonamide, urea, surfactants, thickeners or water and colorants. Among them, polystyrene (or polyvinyl chloride) is a film-forming body, but its adhesion to the fabric is poor, and therefore, a synergistic effect of the acrylic copolymer is required.

Printed on a cold platen. The screen is based on the size of the flower pattern, and nylon screens 11-14 are used. After printing, hot air is dried at about 80°C. Foaming conditions should be 180 ~ 185 °C, lOOs or so. The disadvantages of foamed printed fabrics are that they are easily contaminated and sticky and are suitable for small areas.