Quality control of screen printing raw materials
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
Product quality is related to the survival and development of each enterprise. The quality of products depends on the five major production factors in the production process: Man, Machine, Material, Method, Environment. That is, we often say the 4MIE rule. Due to the large differences in the scale and grade of domestic plastic color printing manufacturers, the emphasis on 4MIE rules and the actual implementation are not the same. Due to the limitation of financial strength, for most small and medium-sized plastic color printing factories, the factors that reduce the quality of printed materials and reduce the quality accidents from the source have strong operability. In the process of plastic color printing, the raw materials are mainly three types of film, ink and solvent. The overall quality control principle: according to the customer's specific requirements or the characteristics of the package contents, post-processing to determine the appropriate film and structure; after selecting the material structure, according to the different film to set the appropriate ink, and supporting the corresponding Solvent; avoid excessive packaging or shoddy.
There are many varieties of films on the market today, but the most commonly used printing films are BOPP, NY, PET, PE. As far as printing is concerned, the most important thing is of course the surface treatment effect of the film, and whether the NY film is damp. The process requirements for the film surface tension of the film should be established during printing. The corona effect is time-sensitive, and if it is left for a long time, the corona effect may fall too much to meet the printing requirements; it is also possible to avoid the trouble of accidentally inverting the film surface printing. PE film is the focus of our attention: there may be a film roll leaking corona treatment when blowing film; excessive or uneven film thickness causes insufficient corona effect; blown film is adding too much slip agent or high Excessive proportion of slip particles causes a significant decrease in corona effect. When the corona effect of the two sides of the 12~15umPET film is not much different, it is easy to cause the back of the printed film roll to be stuck. Corona requirements for printed film: BOPP, PE ≥ 38 dyne, PET ≥ 50 dyne, NY ≥ 52 dyne. After the NY film absorbs water, it will not have a great influence on the corona effect. It is judged whether the NY film absorbs water and sees whether the film shrinks or not. When a film is cut into the oven for several hours, the hand feels hard, if there is a trend If the phenomenon is hard, the NY film absorbs too much water. In the purchase of film must be explained to the supplier of the use and requirements of the film, and now the film variety is refined, light said PET, NY, BOPP name, suppliers may have several varieties, but not necessarily all.
When choosing a gravure ink, there are a few key factors to consider: on what substrate to print? What kind of machine is used for printing? What kind of effect do you hope to achieve? What are the conditions for post-printing processing and end product use? Nowadays, ink manufacturers are fiercely competitive, and there is a lot of room for product selection. It may also dazzle our color printing factory. Confirm the above points before printing, and choose the ink with the best performance-price ratio, and reduce or avoid the occurrence of printing failure. . The supplier of ink should not be too much, not more than three, the ink of different brands can not be blended and used, resulting in a waste of residual ink; perhaps some color printing manufacturers hold the mentality of possessing ink supplier, but the enterprise should be Integrity-based, it is necessary to pay sooner or later, there is no need for this.
Three major types of inks commonly found on the market: polyamide-type surface printing inks, chlorinated polypropylene type composite inks, and polyurethane inks. Different substrates are selected for the corresponding inks. Printing BOPP selects chlorinated polypropylene type composite ink. If it does not need to be compounded, it adopts polyamide type surface printing ink. If general purpose polyurethane ink is used to print BOPP, not only the cost is high, but the adhesion fastness also fails to meet the requirements. NY, PET film must be printed with polyurethane ink. If it is printed with chlorinated polypropylene ink, it is prone to failure such as low peel strength and high temperature delamination. The adhesion of polyamide ink to PE film is particularly good, but it can only be used for general dry packaging. When making high temperature, grease resistant and water resistant packaging, such as milk film and bottle label, polyurethane ink should be used.
There are several basic indicators of ink that our color printing companies should test: viscosity, fineness, hue, and adhesion fastness. Required test tools include a bar (contrast hue, adhesion fastness), 3# Chaen Huai (viscosity), fineness plate (fineness). For viscosity detection, it is best to dilute to a specific viscosity (such as 18 sec / 25 ° C) with a matching solvent to calculate the amount of solvent added, so as to eliminate the "false viscosity" phenomenon that some inks may bring (ink see It's thick, but it doesn't add solvent.) The adhesion test can be selected from the national standard (GB/T 13217.7-91), but for some surface printing inks may not be enough, it is best to simulate the specific requirements of the product packaging and post-processing conditions for testing.
The good quality of solvent quality directly affects the quality of ink printing, but for general SMEs, solvent quality is the most difficult to grasp. The main indicators for distinguishing between good and bad solvents are purity and moisture content. Quantitative qualitative detection of solvents is best detected by chromatography, but the instruments required are more expensive and technically demanding. If the light is for printing, regardless of the dry compounding process, here are a few simple and practical methods. Look at the appearance of the solvent, at least it should be clear and transparent. If there is turbidity and floating matter, the solvent should be used with caution. After smelling the solvent, after a long time of exposure to the commonly used solvent, the operator has a general impression of the smell of a particular solvent. If the solvent smell is not pure, it is certain that the solvent is not high in purity and impurities. many. Use the principle of dissolving effect to roughly determine the moisture content in the solvent: use a 100ml glass measuring cylinder to take a large half cup of transparent toluene solvent, take a small amount of solvent such as ester or ketone to be tested, and evenly pour into toluene. When entering toluene, observe whether there is turbidity (milky white). If it is, the water content in the solvent is seriously exceeded. Experience has shown that when the water content exceeds 0.5%, the phenomenon is obvious. The moisture test of benzene solvents can be carried out by taking a solvent through a long glass tube and observing whether there is delamination.
There are many factors affecting the quality of printing. How can we better grasp the quality of printed matter? Each color printing company has its own management methods. The quality control of raw materials is the most basic and critical process requirement in the color printing process. It is difficult to imagine that unqualified or inappropriate raw materials can guarantee the production of quality printed products. Therefore, our color printing enterprises must make good and effective long-term The quality of raw materials is closed.