Special Screen Printing - Braille Printing

With the improvement of technology and development of signage technology, the use of special printing to deal with the bottom layer of signage panels has become a common means, and colorful, beautiful and moving, not only increased the decorative nature, but also obtained more prominent results. The following will introduce several common special screen printing technology and issues to pay attention to.

Second, Braille printing

With the development of science and technology, we can already print Braille using screen printing and foaming ink. Printed books such as Braille books and documents are completely different from those of general books and periodicals. Braille raised idea size, dot pitch, kerning, and line spacing are fixed in the design according to the physiological and psychological characteristics of the blind person's touch. The shape of the bump is generally hemispherical or parabolic. The diameter of the bottom of the bump is 1~1.6mm, the height is 0.2~0.5mm, and the pitch is 2.2~2.5mm. If the bump is too small and the distance is too close, it will affect the speed of blind touch reaction. If it is too big, it will exceed the most sensitive area where the fingertips of the blind touch. Braille printing methods include mold stamping, ink printing, and foam printing.

(1) mold stamping method. It is the earliest printing method used in Braille printing. When printing Braille, first use a special typewriter to press out the concave point on the double sheet iron to make Braille bump mold. Then the special thick paper is placed between the two mold sheets. After heating and pressurizing, the different raised dots are pressed on the thick paper to make a blind document page. Generally, 120 g thick kraft paper is used. If you find that there is something wrong with the layout, just level the bump and re-erect the correct point. After printing, the book pages are bound into books, which complete the printing of Braille books.

(2) Ink printing method. Braille printing with ink is a major advance in Braille printing. The method is to add a certain proportion of rosin powder and other auxiliary materials into the common ink to make the rosin ink. After using a letterpress or a screen printing, the blind spot or the pattern is printed on the paper, and the ink is heated and baked, and the ink is raised. Braille required. The preparation method of the rosin ink is: melting the rosin into the corn flour, stirring evenly, and then slowly dissolve the color material dissolved in ethanol, stir evenly after printing; can also be added in the offset ink or letterpress ink Rosin powder.

Note: Ink preparation must be strictly in accordance with specifications, proportions, and control the viscosity of the ink, and after the heat uplift should be strong and not brittle, the deformation rate is small. Strictly control the amount of additives added, and the ink consistency is high, the silk should be appropriate. The screen printing effect will be better.

(3) Foam printing. Foam printing is the most widely used method in braille printing. Foam printing is the use of inks with foaming properties printed on the paper, heated by heating foam, the ink rises up, at room temperature, solidified into embossed graphics. Braille foam printing not only can be printed on both sides of the paper, but also can print patterns; printed braille is wear-resistant, soft texture, long-term touch reading does not hurt the fingers and so on.

Foam printing is usually screen printed. The process flow is:

Screen making and foaming ink formulation → screen printing → low temperature drying → heating foaming → binding into a booklet.

At present, the types of foam printing mainly include microsphere foam printing and groove bottom foam printing.

Microsphere foam printing is widely used in new braille printing technology systems. The braille printing system is different from the original braille printing method in that it uses a computer, which can greatly reduce the process of plate making, and can print Braille books in a large amount and quickly. The Braille printing can not only print braille Braille but also can print patterns and papers. Both sides can be printed. The thickness of one book is only 2/3 of the original printing with a zinc plate, which greatly reduces the use of raw materials and operating costs. The foamed ink printing is durable and not easily damaged.

Groove bottom foam printing process is more complex, the paste paste ink is painted or printed on the substrate, printed with a printing roller after foaming; or grooved bottom printing roller printing, after rolling and producing different shapes of bumps Graphic and text.


Source: Screen Printing Industry 2005.8 Qi Cheng