There are many kinds of fabric special printing, foam printing is one of them. Foam printing is characterized by: strong three-dimensional impression, similar to artificial embroidery, soft to the touch, wear-resistant, washable, fastness, good elasticity, and can be widely used in tablecloths, curtains, tea towels, handkerchiefs, pillow covers, clothing, travel Souvenirs and other aspects. It can not only be applied to natural fiber fabrics such as cotton, hemp and silk, but also can be applied to artificial fiber fabrics.
Foam printing application
Foam printing can be applied to the cover of books and magazines. It not only has a bright color, but also has outstanding graphics, durability, low cost, and looks like leather-like paper.
Foam-printed books and magazines cover the outlines of the book's name and the outline of the book's text. If the title of the book is stamped on the cover, it will be more eye-catching and attractive.
Braille books, publications, and general books are printed in different ways. Blind people can't use flat graphic prints, but have to use their hands to figure out various high and low ideas to grasp the meaning of the publication. The Braille books that were published in the past were embossed with 120g thick kraft paper to produce braille. This type of Braille script is easy to collapse and damage. It is also afraid of the tide and the pressure. The volume of the book is so large that it is inconvenient for carrying, mailing, and transporting. The storage space is large and inconvenient. Due to the limitations of the relatively backward production process, only braille can be embossed and the logo cannot be imprinted. For this reason, Braille was printed using synthetic resin, and Brass Braille was imprinted with a thermoplastic hard plastic sheet. Although the process was relatively advanced, However, the fundamental shortcomings of overbooking have never been overcome and the cost is high. Whether the use of resin to cure braille printed braille, or printed in plain braille braille, the texture is hard, and long-term tactile readings can damage the fingers of the blind.
The advanced method of printing Braille using microcapsule foaming printing technology completely solves the deficiencies of the above methods, creates favorable conditions for printing large quantities of Braille books, and realizes lightweighting of Braille prints.
Foam printing can also be used for the production of decorative wallpapers, and printed patterns have a strong sense of relief. The base paper used in wallpapers has high strength and good quality of printing coatings. The foamed wallpaper is beautiful, decorative, and resistant to water, abrasion, and dirt. Even if it is dirty, it can be wiped clean with a damp cloth.
The PVC plastic bricks used for indoor floor and outdoor wall decoration are printed with thick lacquer PVC paint on thick asbestos paper, and then sent into a low-temperature drying tunnel to form a PVC foam layer, which is to be cooled and rewinded. Several colors of gravure printing, such as the addition of inhibitors in 1 to 2 colors of ink can make this part of the color concave, then printed on the surface of the paper coated with transparent PVC surface protection layer, processed by the foaming furnace, that is, Homogeneous embossed embossed foam print with pattern. As a building material printing, it has the characteristics of low processing cost and novelty.
Foaming ink
This foaming ink is based on the gasification of a foaming agent for the purpose of foaming. This ink is made by dissolving a foaming agent in a liquid polyvinyl chloride resin. When the ink is heated, the foaming agent vaporizes, forming numerous tiny pores in the ink layer, and the graphic is foamed and raised.
Foaming ink formula:
PVC resin 100kg
Calcium carbonate 45kg
Dioctyl phthalate 90kg
Dibasic aluminum phosphite 5kg
Azodicarbonamide 5kg
Pigment (coloring) Right amount
The above raw materials are fully ground to form a paste-like resin and diluted with an appropriate amount of solvent.
(1) Polyvinyl Chloride Resin Polyvinyl Chloride Resin is a vinyl chloride resin that is molecularly compounded by emulsion polymerization to form a paste resin and used as a binder in foamed inks.
(2) Calcium carbonate
Calcium carbonate is white crystals or powder. Used as a filler in foaming inks.
(3) Dioctyl phthalate
Dioctyl phthalate is a colorless, transparent oily liquid. It is used as a plasticizer in foaming inks and has better cold resistance and less volatility. This plasticizer can increase the plasticity and fluidity of polyvinyl chloride resin during processing.
(4) Dibasic aluminum phosphite
The dibasic aluminum phosphite is a stabilizer, and the polyvinyl chloride resin gradually decomposes under long-term high-temperature heat and escapes hydrogen chloride gas, which in turn causes the resin to continue to decompose. Therefore, it is necessary to add a stabilizer to absorb hydrogen chloride and prevent the decomposition of the resin.
(5) Azodicarbonamide
Azodicarbonamide is a lemon yellow crystal. Used as a foaming agent in foaming inks. Its decomposition temperature in the air is 195-210°C, the decomposition temperature in plastics is 155-210°C, and the gas evolution rate is 190-220mL/g. Nitrogen and solid residue ethanediamide precipitate during decomposition. This blowing agent is insoluble in common solvents and plasticizers, but it is easily dispersed in the polymer.
(6) Pigments
The main role of pigments is to color the foaming inks, mainly titanium blue, chrome yellow, carbon black, titanium dioxide, magenta, indigo blue, etc., which can be quantitatively added as needed. Pigments must be ground, stirred, filtered, and blended into the binder.
Foam printing equipment
Foam printing equipment is mainly screen printing equipment and baking (pressing machine) equipment.
(1) Foam printing can use ordinary screen printing equipment. At present, there is no special foam printing machine.
(2) After foam printing, drying (or low-temperature drying) is very important. A small area of ​​fabric can be stacked multi-layer racks, a large area of ​​available rope hanging naturally dry. In order to ensure the screen printing effect, the screen-printed fabric should not be subjected to high-temperature baking, and should be dried at a low temperature (not more than 70°C) or normal-temperature ventilation. The use of equipment drying basically does not require heating (in winter can be properly heated), as long as forced ventilation can be at room temperature.
(3) The key process of foam printing is "hot pressing." The hot press machine is composed of two parts: an electric heating platform and a contact platform, which can adjust the temperature and time. Its main technical parameters: temperature control range 50 ~ 300 °C (manual control), control time range 0 ~ 60s (manual control), pressure hot area 26 cm × 38 cm, operating voltage 100/110V, power 1kW. The large-area hot press can be accomplished by a semi-automatic hot-pressing press consisting of a preparation table, a heating machine, a pressurizing cylinder, a conveyor belt, a discharge cooling table, a bearer, and a controller. Simple foaming can be solved with a hair dryer.
Fabric foam printing process
(1) Fabric foaming printing process is as follows.
Pattern design, drafting, bottom-making version → coating photosensitive adhesive → printing version → transfer ink → (fabric dyeing and finishing processing, cutting, other printing) foam screen printing → low temperature drying → foaming (hot pressing) → inspection of a sewing → finished product
(2) Process conditions
Wire mesh number: 80-120 mesh.
Low-temperature drying temperature: At the end of foam printing, normal temperature ventilation (25°C) is usually used, and the time is 3-4 hours. Drying of the fabric is preferred. If baking, its temperature should be less than 70 °C.
Hot-pressing foaming temperature: 115 to 125°C. The composition of the foaming material can be changed as appropriate by pressurizing the contact surface.
Hot pressing foaming time: According to different fabrics, different patterns, different foaming requirements to control, time is 2 ~ 15s.
Hot pressing contact surface: The heated platen is usually in direct contact with the opposite side of the fabric, which is advantageous for foaming, softening, and high hair growth.
Hot pressing pressure is near normal pressure.
Cooling time: sufficient foaming, do not have to consider the cooling time.
Factors affecting the quality of fabric foam printing
Fabric foam printing should achieve both good artistic appreciation and high practical value. Apart from the design level, the influencing factors are various, and there are operating experience and skills factors, as well as factors of raw material variety and quality. .