Transfer printing ink is an important part of the transfer printing process, and it is also one of the key factors in transfer printing technology. General transfer printing inks can be divided into alcohol-soluble, oil-soluble and water-soluble three major categories. Due to the high cost of the first two inks, the environmental pollution is serious. Although the water-soluble disadvantage is that it easily causes the transfer paper to be deformed, considering the small button product, the print pattern is smaller, and the small pattern does not cause the paper to be deformed. Therefore, I will only introduce the preparation methods and auxiliaries of the water-soluble transfer ink and the process requirements:
1. Disperse dye screening method
Disperse dyes not only have a simple molecular structure, but also do not contain ionizable groups, so there is a certain vapor pressure sublimation phenomenon. The rate of sublimation is proportional to the temperature, and the sublimation phenomenon of disperse dyes is utilized by transfer printing. In the disperse dye system, azo dyes and lanthanide series which have a small molecular weight and a small amount of polar groups are dyes that are easily sublimated. The criteria for disperse dyes selected for transfer printing should meet the following requirements:
1) High steam pressure and diffusion coefficient are required, and it is usually selected from 170 to 210°C.
2) The molecular weight is less than 400.
3) The consistency of the dye sublimation property is required when used together, and the level of fastness is met.
According to the introduction of relevant data, the screening of disperse dyes can be divided into two stages: universal selection and testing. First, the low-temperature type (E) or medium-temperature type (SE) disperse dyes that can be purchased can be converted into a paste with a thickener. The screen printing method is printed on the paper, and then it is transferred onto the button. The selection is determined according to whether the color concentration is rich or not, and the selected dye is further screened as follows. Although there are many methods for screening dyes suitable for transfer printing, in addition to focusing on the molecular weight, chemical structure, and selection from the vapor pressure and differential thermal analysis curves of the dyes, the transfer rate method should also be selected: the measurement before and after transfer The change in the dye weight of the dye is determined by the percentage of dye removed and the screening method based on the color depth of the button after printing. This method can be directly linked with the quality of the product and the process performance of the dye, and has a direct guiding role in production. The buttons have good reproducibility in transferring color in transfer printing. Selecting the dye requires an approximate sublimation performance in the transfer temperature range. In general, the dyes generally include: Disperse Red 3B, Disperse Red FB, Disperse Yellow 6G, Disperse Yellow 5G, Disperse Yellow 2GC, Disperse Blue 2BLN, Disperse Yellow RGFL (Due to uneven coloration during transfer, it is not easy to use the large area pattern. Small button patterns can be tried), scattered fluorescent yellow 2, scattered red E-4B, disperse yellow E-3R, disperse brilliant blue E-4R and other dyes. The disperse dyes imported from abroad are used for transfer printing. It is not introduced here one by one. In thermal transfer printing, two or more disperse dyes are often required for the design according to the design of the color tone of the flower, and the compatibility of the dye should be paid attention to in the mixed use. For example, the sublimation point of the dye can not be too different, so as to avoid difficulties in determining the control of the pressing temperature, resulting in different colors and shades of the product. According to the domestic past selection of low-temperature three primary colors disperse red 3B, disperse blue 2BLN and disperse yellow RGEL; and now selected domestic disperse dye low-temperature disperse yellow E-3R, red E-4B, brilliant blue E-4R, as long as the factory reserves Trichromatic dyes and several dyes, including blacks, can be easily formulated with a variety of chromatograms to minimize the need for factory dye stocks.
2. Thickener screening
There are many kinds of thickeners that can be used as printing pastes, but there are only a few suitable for water-soluble transfer printing inks. The requirements for them are that they can make the papers nice, the transfer patterns should be clear, and the affinity for disperse dyes Small; normal temperature has good thickening effect and suitability for printing, but does not decompose at good temperature (220°C), good stability; has certain solubility in water. According to the introduction and screening of relevant data, it is generally appropriate to use methyl cellulose, sodium alginate, etc. as the base material of water-soluble transfer ink. In order to improve the dispersion of the ink, a small amount of a surfactant such as Pingping plus O is added, and if necessary, a small amount of an organic solvent such as ethanol, methylamine aqueous solution, etc. is added to adjust the ink's printability. In recent years, Liaoning Textile Chemistry Research Institute (Dandong Hengxing Fine Chemicals Co., Ltd.) has introduced a series of thickeners in order to meet the requirements of various special printing. Among them, FS-60 series thickener can replace sodium alginate by 100% for dispersion. Dye printing.
Printing paste preparation: As commercial disperse dyes usually contain more anionic dispersant, it has obvious solubilizing effect on disperse dyes. When disposing printing materials, most of dissolvable water is dispersant. The fine dye particles are only surrounded by the water-soluble dispersant, and the aggregation of the dye particles does not occur close to each other. In the preparation, the slurry is firstly adjusted with water at 40° C. which is twice the amount of dye, and diluted with water under high-speed stirring, and the printing paste (ink) is formulated with the original paste (thickener).
Third, the preparation of transfer printing paper
General button companies do not have their own printing equipment, transfer printing paper printing methods, generally can gravure printing, lithographic printing and screen printing, transfer printing an important material of paper, according to the current social industry division of labor, the button manufacturers can be commissioned The printing plant produces transfer printing paper. If the factory adopts self-printing, screen printing is recommended because of less screen printing investment and quicker results. Of course, the button companies set up a printing shop to print on their own, which can prevent imitation of counterfeit products because the imitation of counterfeit products is more serious nowadays. The requirements for printing papers are: paper must have a certain strength, and it should not be brittle or deformed under high temperatures. The dye has a low affinity for paper so that the dye gas can be fully transferred to the button. The printing material on the paper has no obvious blocking effect on dye transfer.
Third, the preparation of transfer printing paper
General button companies do not have their own printing equipment, transfer printing paper printing methods, generally can gravure printing, lithographic printing and screen printing, transfer printing an important material of paper, according to the current social industry division of labor, the button manufacturers can be commissioned The printing plant produces transfer printing paper. If the factory adopts self-printing, screen printing is recommended because of less screen printing investment and quicker results. Of course, the button companies set up a printing shop to print on their own, which can prevent imitation of counterfeit products because the imitation of counterfeit products is more serious nowadays. The requirements for printing papers are: paper must have a certain strength, and it should not be brittle or deformed under high temperatures. The dye has a low affinity for paper so that the dye gas can be fully transferred to the button. The printing material on the paper has no obvious blocking effect on dye transfer.
Fourth, button transfer printing equipment and technology
Most of the transfer printing equipment currently on the market is designed for fabric printing, and individual products are designed for special products such as cups, plates, etc. It is difficult to find a set of special equipment suitable for buttons. There are mainly two types of transfer printing equipment on the market: one is an intermittent flat ironing machine, and the other is a continuous hot roller ironing machine. According to the pressurization mode, it can be divided into two types: pressurization type and negative pressure type (vacuum). Both models are produced in China, but they are not suitable for the button transfer printing type. According to the characteristics of button production, the company develops its own pressing equipment or designs and manufactures it with a printing machine manufacturer. Here, the author designs a soil method for reference only. Buttons are small in size, complicated in variety, and varied in form and size. From the production point of view, they cannot be pressed one at a time. The surface of button press will show various states such as flat, convex, concave and so on. These will cause many difficulties for the button printing. Taking the flat iron machine as an example, this can be based on the layout of the printed paper plate. The batches of printed buttons were arranged on a mold made of gypsum paste and the press nest was positioned. This press nest was consistent with the printed paper plate. When the plaster is hardened and solidified, the position of the button printing arrangement is basically positioned. This positioning mold can be used for several sets of rotation to avoid affecting the speed of flowering. According to the size of the button, each dozen or hundreds of hot flowers can be completed. The matching between the button and the floral paper can use the thermal transfer glue (such as 3M spray glue) currently sold in the market to firmly bond the paper and the button. The two hot plates of the flat ironer are hard (hot plate) soft (cold plate) and soft (hot plate) hard (cold plate). The purpose of doing so is to adapt to the complexity of the surface of a buttoned flower, and also consider that there are two basic conditions for the printing process: one is temperature and the other is time. These can be used to find out the best parameters. Only the size of hot pressure, has little effect on the printing effect. If the transfer printing using vacuum ironing machine, then the effect will be even more ideal.
As a button product, it is a special shape of the substrate, the shapes vary widely, to achieve the printing must be fixed according to certain requirements, in order to make the printing surface and the position of the imprinted parts in line with the requirements of the printing process, which makes The printed surface of the substrate is configured to meet the requirements of the printing process. We call this the positioner. If the button printing positioner is manufactured using a mechanical processing method, it is complicated and time-consuming, and the cost is high. If the resin casting method of the plastic industry is used, it is simple and fast, low in cost, and convenient to use. This kind of casting method is not a good thing for button enterprises, and it will be more difficult for screen printers. You can try out some of the information by referring to relevant materials. Since the space relationship can not be introduced more.
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