Application of the most popular gravure transparen

The application of gravure transparent plastic ink in flexible packaging

with the continuous improvement of people's requirements for packaging, the packaging shape design tends to be diversified, and the color has attracted widespread attention. Most of the outer packages of goods are highly transparent, giving people a dazzling feeling. In the field of flexible packaging, transparent inks with high transparency are becoming more and more popular

transparent ink is more effective when used in aluminum film or aluminum foil printing. Now transparent ink has been widely used in the packaging and printing industry, specifically in food soft packaging, beer carton packaging, tobacco carton packaging and other high-end packaging. However, some problems often occur in the actual process of transparent ink, such as pitting and uneven ink spreading after printing, which cannot achieve the expected effect

types and characteristics of transparent inks

transparent inks are made from high-grade transparent pigments and high-grade transparent resins, plus various additives through fine grinding. Transparent ink is divided into surface printing transparent ink and internal printing (composite) transparent ink. Compared with other inks, transparent inks have the characteristics of low viscosity, high transparency and brightness, bright colors, firm adhesion and strong coloring power. The fineness of transparent inks is generally 10 μ M below, its covering power and transferability are better than other inks. However, the surface printing transparent ink is not as heat-resistant as the internal printing transparent ink. Generally, transparent ink is less used in the heat sealing parts when designing packaging bags. Transparent printing ink inside is generally resistant to high temperature of about 120 ℃

selection of transparent inks

1. Choose suitable inks according to different printing materials. For example, surface printing transparent ink must be selected when printing aluminum plated twisted film. When printing BOPP film and composite aluminum plated film, Jonas Martens, the founder of the company, should be selected to print transparent ink when he was interviewed by the media. The type of printing materials determines the ink used. Even the same kind of film materials will vary according to brand and grade

2. Select transparent inks according to the samples provided by customers, including the hue and color of the inks. If you need to deploy spot color transparent ink, it is necessary to consult the ink supplier, because the deployment of spot color transparent ink is more difficult than opaque ink

3. choose according to the purpose of the package. For example, whether it should be resistant to high temperature, sunlight, penetration, etc

use of transparent ink

1. The gift gold paper used for printing dazzling flowers, color bars, ribbons, etc. is made of aluminum plating after printing with transparent ink (red, yellow, green, blue, etc.) or surface printing with aluminum plating film, which is a single-layer film

2. After printing transparent ink, the inner layer of aluminized film is compounded into a flexible packaging bag, or after printing aluminized film, it is made into a twisted film, which is more than two layers of film and is widely used in the food industry

3. After printing, it is aluminized and then covered on paper to make high-end packaging prints such as cartons, cartons and New Year pictures, which has the advantages of waterproof and moisture-proof

4. After printing with anti-counterfeiting materials, it is printed with transparent ink and covered with holographic film, which is conducive to the anti-counterfeiting of prints, and makes the appearance colorful and radiant. In order to achieve the best effect, transparent ink can not be used completely in the design, but only locally

transparent ink printing failure and precautions

1. Printing transparent ink produces "pitting" phenomenon

cause analysis:

(1) the surface of the embossing rubber roller is not fine enough, or there are foreign matters such as dust, resulting in the ink here is not thick enough

(2) plasticizers and lubricants contained in the film float on the surface, hindering the normal transfer and lubrication of ink

(3) ink viscosity is too high, drying too fast or lack of adhesive causes ink transfer and poor wetting

(4) the printing pressure is too small or the printing plate itself is defective

solution:

(1) wipe the surface of the impression rubber roller clean

(2) preheat the plastic film before printing, heat the film for printing or replace the plastic film

(3) reduce the ink viscosity and use slow drying solvent

(4)1. The mechanical transmission is composed of harmonic reducer, arc synchronous belt and ball screw pair to realize gapless transmission and increase the printing pressure, which is generally about 4kg

(5) if the pitting is regular, carefully check whether the printing plate and the embossing rubber roller are defective. If so, remake the plate or replace the rubber roller

2. Adhesion occurs after printing transparent ink

in the plum rain season with high temperature and humidity, the plastic film is easy to adhere after gravure printing, winding and placing, and the transparent ink is stuck by salty blocks, which cannot be separated from the lower plastic film, resulting in a large number of waste products. Print adhesion is mostly caused by sticky ink, too high environmental humidity, too much pressure, etc., as follows

(1) internal factors

① the ink itself has poor heat resistance and produces greater viscosity under high temperature conditions

② there is too much solvent left in the ink, which causes serious adhesion of the finished product after winding. The large amount of residual solvent not only affects the adhesion fastness of the ink, but also makes the packaging strange, which is extremely detrimental to the packaged food

③ the additives in the printing materials cause the ink to stick

(2) external factors

① the ambient temperature is too high, causing ink softening and printing adhesion. It is required that the operation and use temperature of printed matter shall not exceed 40 ℃

② adhesion caused by too tight winding. Reduce the winding tension

(2) other factors

the ink is not firmly bonded to the substrate, which is easy to transfer and adhere after winding. At this time, the ink should be selected correctly to make the ink quality adapt to the substrate. Surface treatment of substrate to improve the affinity for ink. Generally, the surface tension of BOPP shall not be less than 3.8 × N／m。

3. The gloss of transparent printing ink and aluminized composite is not high

cause analysis:

(1) the transparency of the ink itself is poor

(2) the solvent volatilizes too fast or the ink viscosity is too low during printing

(3) poor reflection caused by poor uniformity of aluminum coating

(4) the angle of the doctor blade is too large and the printing plate hole is shallow

solution:

(1) replace the ink with good transparency

(2) use slow solvent to improve ink viscosity

(3) replace the aluminized film, requiring its surface to be uniform and free of pinholes

(4) adjust the angle of the doctor blade, which is generally 35 °

4. Agglomeration of transparent ink

this phenomenon usually occurs in the case of low temperature. Heat the ink at room temperature of 35 ℃. In order to prevent accidents, special personnel must be assigned to guard it

5. Other precautions

(1) when printing with transparent ink, which is mainly used for medium and low-end exports to developed countries, white is not used as the bottom, because white plays a role of extinction, which greatly reduces the utilization prospect and use effect of this material. The pattern printed with transparent ink is 0.01mm thinner than that with white ink

(2) select appropriate diluent according to the type of transparent ink

(3) due to the low viscosity of transparent ink, it is not suitable to add too much diluent, and the viscosity is generally controlled at 18 ~ 22 seconds (3# chaen cup)

source: fine chemicals in the 21st century