At present, the detection technology of color box printing quality mainly includes density method and chromaticity method. Among them, the density mode is a process control mode, which controls the key links of the printing production process according to the thickness of the ink layer. The chromaticity method is a high-precision system control mode, which performs color control based on the intuitive measurement of chromaticity or spectroscopic spectrum, but requires comprehensive consideration of printing materials, application environment and testing purposes. In terms of implementation, either an offline mode of manual sampling or an online mode of automatic detection can be adopted.

1. Inspection and control of printing quality of special materials

In the color box packaging, the application and innovation of special materials and new materials is a trend, such as the development of cigarette packs from paper soft packs and cardboard hard packs to aluminum foil gold and silver cardboard hard packs. These high-gloss composite or coated materials have metallic luster and refraction surface. After being printed with exquisite patterns of various colors, people feel high-end and elegant, which can greatly increase the value-added space of products, and are widely used in high-end color boxes. Such high-gloss surface materials have strong metallic luster due to the smooth surface coating, and strong specular reflection occurs when incident light is irradiated. Therefore, the color appearance of the surface of the object will change with the change of the observation angle, which makes it difficult to control the color in the printing production process, so that the printing factory is faced with ensuring that the same batch of printed products, and even different batches of printed products, have the same ink color. The quality control problem and its special testing technical requirements. The color box printed with special materials has many spot colors and anti-counterfeiting processes in addition to four-color printing color pictures, and its inspection contents include density, dot enlargement, registration and gloss. Due to the limitation of the surface gloss of special materials, in the measurement of density and dots, it is necessary to use a test instrument that uses d%2F0 to measure optical geometric conditions. Color spectral reflectance, and then obtain color CIELab value and color difference spectrometer, such as X-Rite's SP series. Thus, the accuracy and reliability of the measurement data of high gloss surface materials are guaranteed. Measuring instruments that are applied to the geometric conditions of 0% 2F45 of common materials, such as the X-Rite900 series, cannot achieve consistent and accurate results.

2. Detection and control of spot color printing quality

In the printing of color box packaging products, because spot color printing has a large area of solid color blocks, the color is dazzling, and the shelf display effect is good; the color difference caused by dot overprinting and dot deformation is reduced, and the color is stable and easy to identify. Therefore, a large number of special Color printing is its basic feature. At present, domestic color box printing enterprises are relatively backward in the measurement and control methods of spot color, and most of them are still in the stage of blending spot color ink by relying on the experience of workers and masters. The proportion of spot color ink is not accurate enough, the blending time is long, and the subjective factors have a great influence. shortcoming. Therefore, the use of color matching system is the best solution to the problem, and it is also the mainstream technology and development direction of international color box quality control and inspection. Spot color ink matching system is a system composed of computer, color matching software, spectrophotometer, analytical balance, ink uniformizer, ink spreader and printability meter. The spot color ink matching system can store the parameters of the printing materials, inks and color matching data of the color box printing enterprise in the system database through tests and experiments. Carry out color matching analysis and color matching operations, control color matching conditions according to the CIELab value, density value, and △E of customer samples and color matching samples, and provide printing control parameters, so that the data of spot color ink matching can be realized. For example, the Swiss GretagMacbeth ink formulation system including the hardware spectrophotometer SpectroEye and InkFormulation, its SpectroEye can not only measure the dot and density value of the printed matter, but also the hue (Hue), saturation (Saturation) and lightness (Luminosity); InkFormulation only needs to be extremely An accurate database can be established with a few concentration scales.