In the company, after investigation and research, it was found that in the production process of bottle caps, the aluminum cylinders printed by dry offset printing have a high scrap rate and process waste in the glazing and bronzing processes. In order to improve the production status, reduce the scrap rate in the production process, save the process, and increase the production capacity, it was decided to take the "synchronous glazing and bronzing process based on dry offset printing" as the project topic, apply the professional knowledge learned, through experimental analysis, material verification and Small batch production methods, based on the performance indicators of varnish, the apparent characteristics of the surface of the printed product after glazing, and the apparent characteristics of the surface of the printed product after gilding, can be obtained between the varnish and the gilding paper. The matching relationship provides a basis for the future selection of simultaneous varnish and foil paper.
This research project is aimed at the post-press processing technology of bottle caps, glazing and bronzing. The highlight of this research is that the matching relationship between synchronous varnish and bronzing paper can be drawn, and the corresponding standards are formulated to provide a basis for the future selection of synchronous varnish and bronzing paper, so as to achieve dry offset printing and glazing Synchronous implementation and solve the problem of high bronzing scrap rate after synchronous polishing.
First, the actual production encountered problems and the proposal of the experimental plan
In the actual production process, the roller printing, roller polishing and hot stamping processes encountered a series of problems that need to be solved.
Problems encountered during synchronous glazing: When producing bottle caps, some products require side roller glazing. The glazing method is mainly synchronous glazing. The problems encountered during this period are mainly horizontal stripes and blurred graphics, and corresponding problems occur. The reason is mainly caused by the miscibility of varnish and roller printing ink. In addition, there are cracks, peeling, and peeling of the varnish coating. The reason for the corresponding problem is mainly caused by the varnish hardness is too large.
Problems encountered in hot stamping of synchronously polished products: products that require side glazing and hot stamping. After synchronous glazing, the problem that is easy to appear during hot stamping is that it is not hot or missed. The main reason is that the varnish layer is attached. If the focus is not good, you need to choose the appropriate foil paper. The second is how hot it is, which is mainly caused by excessive temperature, uneven surface of the bottle cap, and excessive pressure. In addition, there is color gold, which is mainly caused by too loose foil paper and excessive temperature. In addition, the phenomenon of flying gold foam will also appear, mainly due to the poor quality of the foil paper.
Generally, the quality inspection department will test the quality of products according to the requirements of national standards.
Experimental scheme: match the existing varnish with bronzing paper, each group tests about 60 caps, observe the test results, and measure and analyze the apparent characteristics of the surface of the cap to find that the varnish and bronzing can be synchronized The apparent characteristics of the matching group with better matching between papers provide a basis for the future selection of simultaneous varnish and bronzing paper.
2. Test and results
In order to obtain the matching relationship between synchronous varnish and bronzing paper, and formulate corresponding standards to provide a basis for the future selection of synchronous varnish and bronzing paper.
1. Experimental procedure
â‘ Roll printing and polishing the aluminum cylinder according to the roller printing process.
â‘¡Measure and analyze the polished aluminum cylinder according to the apparent characteristics listed in the table below.
③Bronze the polished aluminum cylinder at 240 ℃ -270 ℃ using an automatic three-color bronzing (silk screen) machine.
â‘£Measure and analyze the gold-plated aluminum cylinder according to the apparent characteristics listed in the table below.
⑤According to the corresponding analysis value, set the corresponding standard.
The materials used in the experiment are: 5033 varnish, 3003 varnish, Huameidi 6041 varnish, Zibo Kainuo k-308 varnish, four varnishes, K70-220 bronzing paper, BC-220G bronzing paper, 398-220 Gold foil paper Three kinds of gold foil paper, 800 cleaned aluminum cylinders.
The instruments and equipment used in the experiment are: four-color roller printing machine and automatic three-color bronzing (silk screen) machine.
Preparations before the experiment are as follows:
The varnishes used for testing and production are mainly four types: 5033 varnish, 3003 varnish, Huameidi 6041 varnish and Zibo Kenuo k-308 varnish. The varnish performance indicators are measured as follows:
2. Performance index measurement of foil paper used for testing and production
Generally, anodized aluminum is checked by visual inspection and feel to check the color, brightness and trachoma of anodized aluminum. The fastness and elasticity of foil paper are generally rubbed by hand, or glued with transparent tape. In addition, the fewer ends of anodized aluminum, the better.
The technical quality of anodized aluminum foil has the following requirements:
â‘ The bottom layer is painted evenly, without obvious color difference, color bar and stain.
â‘¡The primer coating is uniform, smooth, white and free of impurities, no obvious streaks, sand spots and oxidation.
③Glossiness, when the printing plate temperature is 70 ~ 90 ℃, the packaging color will not change.
â‘£The fastness is to be rubbed by a 100g weight, and the number of times of wear resistance is required to be 2000-3000 times.
⑤ For clarity, it is reasonable to use the fourth-size font for hot stamping and clear strokes without sticking.
The relevant performance measurement records of foil paper are as follows:
3. Data measurement method
â‘ Gloss measurement method.
Gloss refers to the degree of light reflection on the surface of the paint film. The standard board gloss is used as 100% during the inspection. The measured paint film is expressed as a percentage compared with the standard board. There are many factors that affect the gloss of the coating film. Through the inspection of this project, you can know whether the resin, pigment and filler used in the coating product and the ratio with the resin are appropriate. The determination of gloss basically uses two major instruments, namely the photoelectric gloss meter and the projection gloss meter. The former is used in this experiment.
â‘¡Measurement method of surface hardness.
The pencil hardness method for coating film hardness is used in production. The coating film hardness pencil measurement method is to scratch the coating film with a pencil of known hardness index, and the hardness index of the pencil is used to indicate the hardness of the coating film. According to industry standards, the hardness of pencil refills is divided into 13 levels. It gradually decreases from the hardest 6H, through 5H, 4H, 3H, 2H, H, and then through the soft and hard HB, and then from B to the softest 6B. This is a scientific hardness system with strict definition of hardness value. In the paint industry, this series of pencils with different hardness is used to detect the hardness of the coating film, and the test result obtained is called the pencil hardness of the coating film.
â‘¢Adhesion measurement method.
Determination of adhesion of glazing products:
The aluminum-plastic simple plastic cover can be visually inspected after the sealing test; after the aluminum-plastic cover is rolled according to the finished process, apply appropriate force to the roller teeth with nails (as long as the cover is not deformed), perform a visual inspection after scraping test, and observe the waste Rate (nails cannot be sharp nails just trimmed).
Determination of adhesion of bronzing products:
Soak them in 45 ° warm water and 50 ° white wine for 10 minutes respectively. After air-drying, wipe them 6 times with a clean soft cloth at the same position. Observe the waste rate (special requirements for products must be soaked in 50 ° white wine for 10 minutes. Immediately use your thumb to rub 5 times on the bronzing pattern or gently scrape 2 times with a nail scraper to see if the pattern drops, and observe the color of the wine body. If there is no drop in the pattern and the color change of the wine body is a qualified product).
â‘£Measurement method of coating film leveling.
The four kinds of varnish used in the test were scraped on the aluminum plate coated with general varnish, and the mark was made. Two aluminum plates were scraped with each varnish and placed in an oven to dry. After 10 minutes, the surface appearance was measured. Performance, and comparative analysis to draw corresponding conclusions.
4. Test results
Through experiments, the final gloss data of the four types of varnish after blade coating (three sets of each varnish are measured, and then the average value) can get the following data:
3. Conclusion
Through a series of simultaneous glazing and bronzing tests, the matching relationship between four test synchronous varnishes and three bronzing papers was obtained:
1.5033 The varnish has good synchronous varnishing effect, and the picture and text are not blurred; after rolling, the varnish has no skin and good adhesion; it matches all three types of bronzing paper, and there is no blistering; the adhesion is tested with 50 degrees liquor After 10 minutes, dry it naturally and wipe it with a clean soft cloth at the same position 6 times.
The test proves that the matching relationship between 5033 varnish and bronzing paper can meet the requirements of simultaneous polishing and bronzing.
2.3003 varnish synchronous glazing effect is good, the picture and text are not blurred; match three kinds of gold foil paper, the gold foil has no leakage phenomenon; soak in 50 degrees white wine for 10 minutes during adhesion detection, and dry naturally with a clean soft cloth in the same Wipe the position back and forth 6 times and pass.
3. Huameidi 6041 varnish has a good synchronous varnishing effect, and the picture and text are not blurred; after rolling, the varnish has no skin and good adhesion; it matches all three types of bronzing paper, and all the bronzing leaks. The bronzing paper is attached to the surface of the varnish The focus is extremely poor, and the bronzing is unqualified.
The test proves that Huameidi 6041 varnish can meet the quality requirements of simultaneous polishing, but it can not meet the requirements of bronzing. The matching relationship between Huameidi 6041 varnish and bronzing paper does not meet the requirements of simultaneous polishing and bronzing.
4. Zibo Kainuo K-308 varnish has a high rate of synchronous varnishing waste products, and there is a phenomenon of blurry graphics and synchronous varnishing effect is not good; matching with three types of bronzing paper bronzing, serious leakage, bronzing paper attached to the surface of varnish The focus is extremely poor, and the bronzing is unqualified.
The test proves that the synchronous varnishing effect of Zibo Kainuo K-308 varnish is general, and the image is blurred, which does not meet the quality requirements of synchronous varnishing. Matching with three types of bronzing paper bronzing, serious leakage, and the adhesion of bronzing paper on the surface of varnish Very poor, unqualified bronzing.
Through a series of tests and analysis studies, it has been concluded that products that can be coated and stamped simultaneously after dry offset printing use varnish and foil paper to meet the following standards:
5. Varnish
6. Bronzing paper
In this paper, the specific characteristics of the matching effect between the synchronous varnish and foil paper are obtained through specific experiments, and the corresponding standards are obtained based on this data. However, because the company's equipment used for production practice is different from the experimental equipment used for research, the conclusions still need to be verified in future production practice.
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