Abstract : In this paper, the formulation and properties of a wax thermal transfer ink with a wide range of raw material sources and high quality and low price are introduced. The ribbon has the characteristics of non-deinking, clear writing, good abrasion resistance, high quality and low price, etc., and has no environmental pollution and high application value.
Key words: thermal transfer; ink; ribbons; preparation methods; economic benefits; social benefits
With the rapid development of industry and improvement of product quality management, many industrial products such as instant noodles, small foods, cosmetics, alcohol, beverages and other packaging materials need to be printed on the production date and shelf life, and some need to print product identification. Bar code and security signs. The widespread use of computers and the improvement of printing levels require the rapid printing of tickets (such as bus tickets, train tickets, ferry tickets, etc.) and many documents. These jobs are partially printed on the corresponding printer (or code) by thermal transfer ribbons. Machine) completed.
At present, there are two types of inks used in thermal transfer ribbons: solvent type and wax type: the former has many types of ink preparation materials, and the cost is relatively high. Preparation of ribbons requires drying processes and the presence of solvent evaporation to varying degrees. The problem of environmental pollution; while the latter basically does not have the above problems. This article provides a method for preparing a wax ink with a wide range of raw materials, high quality and low cost, and a ribbon.
1 Experimental section
1.1 Ink materials and their formulations
Ink materials and recipes are shown in Table 1.
The synthetic wax was smelted from 50% paraffin, 40% stearic acid, and 10% rosin.
1.2 ink preparation method
After the weight of each component was weighed according to the above formula, all the components except the pigment were mixed together and heated in a metal heating vessel until completely melted, and then the pigment was added to continue stirring. The material was immediately transferred to a three-roll mill for roller milling until the pigment particle size reached 10 Î¼m or less. The grinding time depends on the amount of grinding mixture in the machine, usually after 3 to 4 times grinding can meet the requirements.
The roller-pressed mixture is poured into a disperser having a rotational speed of 900 to 1200 rpm and a capacity of 20 to 50 liters, and the power is turned on. The electric furnace is heated to about 1500 DEG C. to completely melt the randomized electric furnace and randomly The apparatus is operated to be completely uniformly dispersed into a colored fluid mixture, which is a thermal transfer ink.
1.3 Ribbon preparation method
Pour the ink from the disperser into the ink fountain of the special ink layer coater (with heat insulation device), install the polyester plastic film roll (base tape) to be coated with ink layer, start the coating machine, open the lower valve of the ink fountain The ink in the ink fountain is evenly coated on the polyester film with a running speed of about 20m/min along the lower slit opening, and is rolled on the roll of the machine, and is naturally cooled and solidified at a room temperature and moderately adhered to the plastic film. The thermal transfer ribbon developed by this invention was formed.
The ribbon semi-finished products unloaded from the coating machine are cut into a certain size ribbon roll by a special slitting machine according to the user's order specification, and are packaged in a plastic film or a ribbon cartridge to obtain a ribbon product.
1.4 Common Ribbon Sample Performance
According to the actual user needs and the product's own characteristics, the main performance of commonly used ribbon samples is shown in Table 2.
2 Results and Discussion
2.1 Selection of Ink Formula
Thermal transfer ink is a new type of ink, which is very different from ordinary ink. Because the thermal transfer ink is first attached to the baseband, the required part of the ink layer is transferred to the surface of the object to be printed by heat during use, and the common ink is printed at one time. Therefore, the quality requirements of the ink are greatly different. . For example, ordinary inks are expected to have as good adhesion as possible, while thermal transfer inks have moderate adhesion, too large to complete the transfer process, too small ink ribbons to be easily deinked (waste), and poor adhesion after ribbon transfer. Thermal transfer inks have specific requirements in terms of handwriting definition, print temperature, and the like. Therefore, it is not easy to screen an ideal thermal transfer ink formulation, and the specific performance requirements for each component are very strict. For example, there are many types of vinyl chloride-vinyl acetate copolymer resins, and the degree of polymerization and the ratio of monomer polymerization have a great influence on the product performance. Therefore, the selection and exact amount of raw materials in the formulation need to be continuously discussed based on actual application conditions.
2.2 Improve the permeability of the ink under heat
In the process of ribbon preparation and thermal transfer, the inks are in the molten state, and the adhesion of the inks is mainly due to the resin. Therefore, the resins must use thermoplastic resins. The modified polyvinyl acetates developed by the author have excellent application effects. Stearic acid and rosin with a relatively high melting point play a great role in the permeability of the ink. Experiments have shown that the addition of a suitable amount of this polar substance is very effective in improving the adhesion and rub resistance after thermal transfer printing. There are benefits. At the same time, the surface-active stearic acid and rosin also played a positive role in the full dispersion of the pigment.
2.3 Selection of colorants
The colorant may be a dye or a pigment. Usually, more pigments are used in the thermal transfer ink. When pigments are used as colorants, it is ideal if the pigments are first microencapsulated.
Two or more kinds of pigments or dyes can be used for coloring in order to make the coloring effect bright and beautiful. Commonly used pigments or dyes are carbon black, iron black, iron blue, iron red, phthalocyanine blue, phthalocyanine green, permanent red 2B, evergreen red 7B, Lisol red, magenta 6B, benzidine yellow 2C, Yong Solid yellow GT, titanium dioxide and so on.
2.4 Heating temperature control
In the production of ink, the heating temperature should be controlled, the temperature is too high, it will cause some resin coking and decomposition, and even a fire accident! In principle to meet the melting temperature is appropriate, and constantly stirring to prevent local overheating.
In the coating, it is also necessary to control the proper temperature. If the temperature of the ink is too high, the base tape may be deformed and the ink ribbon may come off. When the temperature is too low, the ink becomes semi-solid (or solid) and the coating process cannot be achieved.
During thermal transfer, the temperature of the printer (or coder) head is also adjusted, which is crucial to the printing effect.
Thermal transfer inks and ribbons have a great market prospect as a new type of high-end consumables. Due to the particularity of its preparation methods and usage methods and the marginal cross-cutting nature of the subject areas involved, there are currently no relevant standards, and many aspects need to be thoroughly discussed and studied. (Wen / Liu Changchun Yao Qiaoling Zhang Yuyin)
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