Similarities and differences between plastic printing and paper printing

Plastic printing and paper printing are the same

(1) The art decoration design, plate making equipment, and plate making process of color manuscripts are basically the same.

(2) The structure of the printing press, the embossing method, and the printing principle are the same. Multi-color rotogravure rotary presses and multi-color flexographic rotary presses can be used both for printing plastics and for printing roll wrappers.

(3) The color formation of color prints is the application of a variety of different colors of ink through the deployment, overlap or a variety of color dot juxtaposition, forming more new colors. Make the product colorful, lifelike image, artistic appeal.

(4) The process of copying color images: From the point of view of color science, it is accomplished through three stages: color decomposition, color transfer, and color combination.

The difference between plastic printing and paper printing

(1) The printed substrate is different. One is plastic film, and the other is paper. There are great differences in their physical and chemical properties. The paper surface has a certain degree of roughness, good adsorption state and capillary action, and the printing ink is easily attached on the paper surface. Before printing, the paper needs to be laid flat in the room for a period of time to dry paper, and a static eliminator is installed on the printing machine to eliminate static electricity and be used for printing. The plastic film is different, such as polyethylene and polypropylene films with the most amount of packaging, the surface finish is high, the inertness is strong, the strength is low, the chemical stability is strong, the ink infiltration is not easy to accept, and the plastic itself has the antioxidant properties. Both will affect the drying of the plastic after printing, affect the adhesion of the ink layer and the film.

(2) Ink cannot be used interchangeably. Paper printing and plastic printing Due to the different characteristics of printing materials, printing ink drying methods and connection materials are different. Therefore, the printing ink cannot be used to print a plastic film, otherwise the conjunctiva cannot be dried. Even when the same kind of plastic film is used, the printing speed and the imprinting method are different due to the use of different printing machines (gravure printing or flexographic printing), and the difference between “printing” and “printing” is different for the binder in the ink. Additives also have different requirements.

Therefore, the use of two different types of plastic inks, imported plastic gravure inks and domestic plastic gravure inks is not permitted. Otherwise, failures such as separation and quality change are likely to occur, causing unnecessary economic losses. (Dou Xiang)

Related to a plastic packaging and decoration printing industry is developing along with the development of social commodity economy. In modern economic life, commodity packaging has become an important part of commodity production. At present, the per capita consumption of plastic packaging in developed countries has been an important indicator of a country’s industrial level. Since the 1980s, plastic packaging materials have accounted for 44% of the entire packaging industry. Plastics in China will grow at an annual rate of 8%. The focus of development is plastic food packaging, plastic packaging substrates and composite packaging materials.

Relevant two plastic film and plastic composite series bags have the advantages of non-toxic, tasteless, moisture-proof, oxygen-proof, strong air-tightness, stable chemical properties, no breakage, low price and less than carrying. After the printing of transparent plastic film, the image is particularly clear and bright, bright color, has a description of goods, effectively protect the goods, reproduction of the product's shape, style and color features, can reflect the high quality of goods, highlighting the sense of the times.

Relevant three (1) can send the printability of the plastic film, and can improve the fastness with other materials. Because the commonly used polyethylene and polypropylene are basically non-polar molecules, they have low surface tension, strong inertness, and are not easy to accept the infiltration of ink, and are not easily bonded with other materials. Therefore, corona pretreatment should be performed before printing and compounding, and printing or compounding can be performed immediately after processing to obtain good fastness.

Relevant four plastic printing inks usually need to consider the following factors: (1) the speed of the printing press; (2) the structure of the drying system; (3) the characteristics of the printing material; (4) the indoor temperature and relative humidity; (5) the printing plate Type, the solvent can not corrode with the printing plate; (6) should have good dissolving ability, does not contain any mechanical impurity and free acid, alkali and moisture; Have good evaporation rate (commonly called dry). These several requirements are the key indicators for selecting ink solvents. (7) The solvent cannot react chemically with the components of the ink; (8) The odor is small, the toxicity is low (the most ideal solvent is non-toxic and odorless), the volatile gas must meet the requirements of environmental protection, and it should be used for food packaging. The actual non-toxic grade; printed products can not have residual solvent odor. (9) Storage stability, no decomposition, no moisture absorption; (10) Low price and abundant supply.

("China Packaging News and Printing Weekly")