Bar code printing process requirements

The color matching of the ink should fully consider the color cast of the ink, and the color cast of the ink has a great influence on the accuracy of the barcode. Theoretically speaking, as long as the ink is used according to the color matching ratio, the requirements for barcode printing can be satisfied. However, due to defects in the printing ink that have a coloring phase, the color cast occurs. Therefore, the color of the ink should be accurately controlled so that the ink density is uniform, the hue is saturated, and the purity is high. It is preferable to determine whether the reflectance of a certain ink under red light meets the requirements before printing the barcode. The reflective and glossy properties of gold ink can cause specular reflection effects that affect scanner readability and therefore cannot be used to print bar codes. In addition, the concentration of the ink and the thickness of the ink layer should also be suitable for the bar code printing requirements. Since the bar code printing is a solid printing, the reflection density that the printing can reach is related to the optical characteristics of the ink and the ink layer thickness. During the printing process, the printed reflection density increases with the increase of the thickness of the ink. When the thickness of the ink reaches a certain value, the density reaches saturation. The general ink saturation density requirements are: black ink 1.8 to 2.0; cyan ink 1.45 to 1.70; magenta ink 1.25 to 1.50; yellow ink 0.9 to 1.05; other spot inks 0.8 or more. Due to the difference in the printing process, the thickness of the printed ink layer is also different, generally offset printing is 2 ~ 4μm; embossing printing is 8μm; flexographic printing is 10μm; gravure printing is 12μm; screen printing is 30μm.

2. The requirements for the substrate.

Since the scanning light source is incident at an angle of 45° and the collection angle of the reflected light is 15° due to the barcode reading, when the reflected light exceeds the range of 15°, the reflected light signal cannot be collected, which is equivalent to the black effect. Therefore, in order to satisfy the characteristics of bar code scanning, substrates are required to have good light scattering properties and specular reflection cannot occur. Therefore, the white quality, opacity, and gloss of the paper have a certain influence on the reading of the barcode. In addition, consideration should also be given to materials that have good weatherability, dimensional stability after stress, good colorability, low ink permeability, moderate smoothness, and good finish.

3 print quality requirements.

The bar code symbol is the source of information for scanning and reading. In order to ensure correct reading, the printed bar code should be neat and clear, the symbol should not be obviously incomplete, and there should be no dirty ink in the blank space. In order to ensure the correct reading of the barcode, the maximum diameter of the defects and stains on the barcode should be less than or equal to 0.4 times the standard width of the narrowest line code. The lines and spaces in the printed bar code should have obvious contrast signals. The reflectance of the blank should be as large as possible, and the reflectance of the line should be as small as possible. The larger the PCS value (color contrast), the contrast signal of the bar code. The bigger the reading performance, the better.

4. Print position requirements.

The position of bar code symbol shall be determined in accordance with the principles of non-deformation, easy reading and plate making. That is, it is required to be set on the right side of the main display surface of the package or on the plane where the main display surface is connected, and on the back side of the main display surface of the package. Taking into account the printing process characteristics, the bar code direction should be made to correspond with the printing direction, so that the printing distortion can only be expressed in the bar code longitudinal position, so as not to affect the accurate reading. Due to the difference in packaging methods and characteristics, the bar code printing position is also different. General box packaging bar code printed on the right side of the bottom of the box; canned and bottled packaging bar code is best printed on one side of the label below, but the bar code symbol surface curvature can not exceed 30 °; barrel-shaped packaging bar code is best printed in the barrel Side, if the side can not be printed, the bar code can be printed on the lid, but the depth of the lid can not exceed 13mm; bag-shaped package with a bottom and the bottom is larger, the bar code can be printed on the bottom or printed on the back of the lower center; The bar code is usually printed on the bottom left corner of the back cover or the cover, and the direction of the bar is parallel to the spine. In summary, barcodes are used as a kind of data input technology and automatic identification technology. They are widely used in the packaging of goods. They play an important role in the production, sales, storage, inspection and communication of goods. Therefore, correctly understanding and understanding the bar code knowledge and printing the bar code is an important part of packaging and printing.