Home Uncategorized What is the specific process of flexible packaging printing? To be detailed, thank you

What is the specific process of flexible packaging printing? To be detailed, thank you

by admin

Flexible packaging printing with intaglio

flexographic printing has received unprecedented attention in China, and many flexographic printing equipment have been introduced. Many people in China believe that flexographic printing is a new process, which will replace gravure or offset printing, and even believe that there is a wave of “glue to soft, concave to soft”. This view is partial. In fact, gravure printing and flexographic printing are not new printing processes. They have experienced many years of development, but flexographic printing has really attracted attention in China in recent years. Now, the international community is more and more inclined to adopt a more fair and tolerant attitude towards gravure printing and flexo printing
the main application fields of gravure and flexographic printing are roughly the same, but not exactly the same. Gravure and flexographic printing have different advantages in the fields of packaging and trademark printing, publishing printing, decorative printing (wood grain paper and transfer printing) and other special printing (such as printing of negotiable securities such as banknotes, stamps and lottery tickets)
packaging and trademark printing are the main competitive areas of gravure and flexographic printing. In this field, the main application products of flexo are corrugated board, label, flexible packaging and folding carton

with the increasing social demand for plastic flexible packaging year by year, plastic packaging is covering the market according to its inherent characteristics of gorgeous color, novel pattern and convenient use. However, due to the lack of technical data for manufacturing and material selection of most small and medium-sized packaging color printing enterprises and the lack of popularization of professional knowledge, the packaged goods have become southern, with huge losses and difficult to expand the packaging business. I put theory into practice and put forward some suggestions for many colleagues in the field of flexible packaging

generally, printing methods include embossing, gravure, flat printing, silk screen printing, etc. Plastic printing is gravure printing. The gravure printing machine often mentioned refers to the unit (or arrangement) gravure printing machine

1. The printing speed of the printing press

Plastic printing unit is determined by the paper walking distance between the printing color groups of the printing press and the effect of the drying box. The longer the color distance and the better the effect of the oven, the faster the printing speed. On the contrary, the printing speed will not go up

for the accuracy of the printing press, in addition to the synchronous operation of each part in front of and behind the printing press, it also requires that the tension control system of each part has good stability. Only when the tension control design is reasonable, the feeding is stable and the winding is stable, the printing will not run and the accuracy of the color registration can be maintained

2. Printing plate

the production of gravure plate is divided into corrosion (manual plate) and electric engraving (electric engraving plate). At present, the price of manual plate is low, but the printing effect is still good, especially the hierarchical plate. In practice, it is found that electric engraving has high requirements for ink. The quality of printing plate production directly affects the printing effect

3. Ink

plastic gravure printing ink is divided into solvent ink and water-based ink. Solvent ink is divided into surface printing ink and internal printing ink (composite ink)

surface printing plastic gravure ink: the surface is smooth and glossy, which is more resistant to friction and smells than internal printing ink. Single component glue should be used for lamination processing, which has poor adhesion with two-component glue. Note that the glue amount should not be too large. Surface printing ink is divided into ordinary ink, water-resistant ink (beverage packaging ink), label ink (calendar ink), transparent ink, etc. Water resistant ink is mainly used for printing on milk packaging, beverage packaging and frozen food packaging products. Label ink is very smooth, anti adhesion and scratch resistance. It is the best ink for printing all kinds of labels. Transparent ink is a special ink for printing aluminum foil and aluminum foil

the inner printing ink (composite ink) is characterized by bright color, tasteless printing and high peel strength, but the conjunctiva is soft and not wear-resistant. It is considered that the printing is dull, which is conducive to lamination processing. If gluing dry compounding is adopted, two-component glue should be used. One is to increase the composite firmness, and the other is to have a small smell. However, when one component glue is used for compounding, the ink on the printed matter will often be dissolved or the compounded finished product will bring the harmful smell of glue, and the compounding firmness is poor (note that alcohol solvents are not allowed to be added). In addition, there is common compound ink in the internal printing ink, which is the ink printing of OPP film (polypropylene film). Polyester ink shall be used for printing PET film (polyester film), and its printing pattern is more firm without adhesion. In short, what type of special ink is used on what film is the principle of ink for plastic gravure printing

water based inks are usually used for printing paper products, including paper plastic composite products. Its characteristic is that it can meet the ink absorption of paper printing and make the printing color plump. What’s more, its solvent is water and ethanol, which has little environmental pollution. It is known as a green ink for environmental protection

4. Compounding

compounding of plastic flexible packaging, including film extrusion compounding, dry gluing compounding and glue free hot pressing compounding. Extrusion compounding refers to extruding PE or PP material into a film after hot dissolving, and hot pressing compounding on the printed film to form a composite finished product. It is characterized by low cost and reduced glue pollution. However, the effect will be better if we choose the best extrusion material and control the extrusion temperature, and add a small amount of glue or AC agent as coupling agent between film-forming
the length of drying channel of dry gluing laminating machine. Heating mode, gluing mode, gluing amount control, material tension control, hot drum temperature control and whether there is a cooling and shaping device constitute its price and grade. In the gluing and compounding process, first of all, the user should understand that if the gluing is to be uniform, the glue must be diluted, and if the viscosity of the glue is to be restored, the solvent on the coating must be volatilized (i.e. the concentration process). Therefore, the gluing amount on the composite is the key to the compounding process. Special attention shall be paid to reducing the amount of glue during compounding. Therefore, it is recommended not to use it in food packaging

since the single component glue is used with surface printing ink and printed matter, it is difficult to eliminate the smell, so it is recommended not to use it in food packaging. Special attention should be paid to reducing the amount of glue when compounding

If two-component glue is used for lamination, in addition to the proportion of glue according to the technical data provided by the manufacturer, attention should also be paid to the content of curing agent, and the amount of glue should be reasonably controlled to reduce the generation of odor and glue spots on the laminating products

in addition, if PE film is to be used as laminating lining, special attention should be paid to the surface tension of PE film. Generally, it should be above 45-52 dyne to ensure the firmne
ss after laminating (it is recommended to install an electric spark processor on the laminating machine)

5. Plastic film

due to the different requirements of the packaged goods, the plastic film required for different packaging is also different. The properties and uses of the most commonly used plastic films are briefly introduced below

PE film is also known as polyethylene film, which is widely used. It is characterized by low cost, good waterproof, but poor gas resistance. Low pressure polyethylene has small extensibility and high tensile strength. It can make the packaging bag very thin, but the heat sealing performance is poor, so it is not suitable to be used as composite lining film. High pressure polyethylene film has high extensibility and good impact resistance, but it is not suitable for composite lining film of fried food and real and cooking bags

PP film is also called polypropylene film. It has high transparency, high strength, good gas and water resistance, but poor oxygen resistance. This film shall not be used as fabric for vacuum, cooking, medicine, beverage and other packaging. CPP unidirectional stretch polypropylene film and heat sealable unidirectional stretch polypropylene film are good and most commonly used composite linings for vacuum packaging or cooking packaging

pet, also known as polyester film, has high tensile strength, poor impact resistance, high transparency and good oxygen and gas resistance, but it is not resistant to sunlight and has low water vapor permeability. It can be used as the fabric and substrate of ordinary vacuum bags, medicine bags and aluminized bags. Not suitable for cooking bag

PA film, commonly known as nylon film, is currently used as the fabric of cooking packaging bags. The cost is high, and the general vacuum bag is not used

other films, such as PE fresh-keeping film for vegetables, fruits and meat packaging, water-soluble PVA film, PVCD high resistance diaphragm, PVC, PP, PE heat shrinkable film
producers and users should select the necessary fabrics and lining materials for packaging according to the inherent characteristics of various film materials, and strive to produce qualified packaging bags with economic benefits, high quality and low price

6. Appendix common diluent ratio of plastic gravure ink for reference:

I. diluent ratio of plastic gravure ink for internal printing:

fast drying solvent: ethyl acetate 20%, toluene 80%
medium dry solvent: butyl acetate 20%, toluene 80 or 100%
slow drying solvent: butyl acetate 20%, xylene 80%
(Note: alcohol solvent cannot be added)

II Proportion of diluent used in surface printing plastic gravure ink:

fast drying solvent: ethyl acetate 20%, toluene 80%, isopropanol 40%
medium dry solvent: ethyl acetate 25%, toluene 50%, isopropanol 45%
slow drying solvent: xylene 50%, isopropanol 50%
ultra slow drying solvent: xylene 50%, isopropanol 50%, n-butanol 3%

at present, flexible packaging is mainly printed by intaglio printing. Since the introduction of hp20000 plate free digital machine in Guangdong dimitt, flexible packaging has entered the era of digital printing

or thousands of apples hanging in my father’s garden,

forehead touching the dark sky, Red soldiers

crawling in the hotel room

looking up at the sky,

can you hear a call at night? Ah, sleeping people

always give you high quality for the rest of your life

flexible packaging printing is divided into gravure printing, flexographic printing, offset printing, digital printing and screen printing
each printing method has different advantages and disadvantages, so it is suitable for different purposes. Of course, the process is different
if you want to know more about gravure printing, you can go to the PP forum. There are detailed professional introductions, and there are many people in the gravure printing industry who can communicate

there are many articles on Printing Technology on PP forum. You can search Baidu: PP Forum on flexible packaging printing technology, and you can find those articles

Related Posts

Leave a Comment