Three-dimensional printing process content and characteristics
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The characteristics of the three-dimensional printing are: the pattern of the printed fabric has a fascinating three-dimensional effect, washing resistance and friction resistance.
The three-dimensional printing method and the process and equipment used are similar to the general paint printing. The main difference is that the printing paste contains microcapsule preparation or foaming agent, so that the pattern can be rapidly expanded and bulged during post-press heat treatment to form a gorgeous appearance. The three-dimensional shape. There are various types of three-dimensional printing, among which the velvet printing and the foaming printing are well known. The foaming technique of the two is quite different from the three-dimensional pattern formed. Under the microscope, the surface of the piled print is piled with numerous tiny soap-like spheres, while the foamed print is a bee-like cake. Therefore, the napped printing products have a unique embroidered effect, while the foamed printing products have a vivid relief effect.
The printing paste for the pile printing consists of a microcapsule preparation, a binder, a crosslinking agent, urea, a coating, a thickener or water. The microcapsules are small hollow spheres with a particle size of about 50/um. The walls are composed of vinylidene chloride and acrylonitrile (about 2:1) copolymers, while the core contains low boiling points such as petroleum ether. Organic solvent. The microcapsules are dispersed in an emulsion such as polymethacrylic acid. The above solvent rapidly vaporizes at a high temperature, and like the blowing of soap bubbles, the volume of the microcapsules is expanded, and the enlarged microcapsules are pressed against each other, thus forming an overlapping distribution like a pile. Therefore, this foaming method is a physical foaming.
Generally, a polybutyl acrylate-based emulsion, or an acrylate and butyl acrylate copolymer, or a methyl methacrylate, methyl acrylate, and acrylamide copolymer emulsion is a binder for the velvet printing. To increase the rigidity of the three-dimensional printing pattern, an ethyl acrylate and styrene copolymer emulsion can be used. A crosslinking agent may also be added as necessary. The amount of coating should not be too much. Otherwise, after the microcapsules are expanded, the paint deposited between the microcapsules has an adverse effect on the velvet feeling.
The flat screen printing between 27.6 and 35.4 mesh holes/cm (70-90 mesh) is most suitable for napped printing. After printing, it is dried at around 70 °C, and heat-treated at 100-140 °C with a heat source such as hot air, hot plate, hot roller or infrared lamp for 30-60 s. The effect of blowing the fabric printing surface with hot air is the best. In order to prevent the expansion, it is preferable to contact the heat source with the back of the fabric when foaming with a hot plate or a hot roll. The disadvantage of the velvet printed fabric is that it cannot be ironed after washing, otherwise the microcapsules disappear and the velvet effect becomes ugly. Such fabrics are also susceptible to staining. The remedy is to add a coating agent.
The foaming printing agent is prepared by mixing a foaming agent with a suitable film former, a crosslinking agent, an emulsifying paste and a coloring agent, and printing on the fabric. After the printing, the foaming agent is thermally decomposed at the time of high temperature treatment, so that a large amount of gas is generated, the film forming agent is slightly expanded into a film, and the gas released by the foaming agent is contained in the film, so that a novelty is formed. Three-dimensional pattern. This foam printing is chemical foaming.
A 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, 36% are gases, and gases consist of nitrogen, carbon monoxide and carbon dioxide. When urea is added, depending on the amount of urea, the decomposition temperature of azodicarbonamide can be lowered from about 200 ° C to about 180 ° C or even 150 ° C. Azobisisobutyronitrile is a white crystal, insoluble in water, and can also be used as a foaming agent, and its decomposition temperature is only 90 to 115 °C. However, its application is limited because it contains toxic tetramethylsuccinic nitrile. The foamed printing paste is generally composed of polystyrene, methyl methacrylate, butyl acrylate and acrylamide copolymer emulsion, azodicarbonamide, urea, a surfactant, a thickener or water and a colorant. Among them, polystyrene (or polyvinyl chloride) is a film-forming body, but the adhesion to the fabric is poor, and therefore, the synergistic action of the acrylate-based copolymer is utilized.
Printing is done on a cold platen. The screen is made of nylon mesh No. 11-14 according to the size of the flower. After printing, it is dried by hot air at around 80 °C. The foaming condition is preferably 180 to 185 ° C, about 100 s. The disadvantage of the foamed printed fabric is that it is soiled and sticky, and is suitable for small-area use.