Evaluation and certification of chemical materials

The evaluation and certification of chemical materials by Fogra Association

its renewable environmental protection has been much concerned by environmentalists. Fogra association is the abbreviation of German Fogra Printing Technology Research Association. Founded in 1951, this institution with more than 600 researchers aims to undertake relevant research projects in the printing field in an independent role and use these research results to promote the development of the printing industry

in view of the existence of a large number of complex production standards and product certification in the field of printing chemical auxiliary materials, Fogra Association, with its rigorous research platinum model, also equipped with a 0.25 carat diamond degree and method, which is really close to the research perspective of the needs of printing enterprises, as well as the recognition and support of a large number of representative manufacturers, has launched a series of evaluation schemes and test certification, which have established a very authoritative position in the world

fountain solution

in order to test the basic effect of fountain solution quickly and reliably, Fogra Association, considering that printing plants and small laboratories generally do not have professional laboratory equipment and conditions, proposed a method that can accurately and conveniently detect fountain solution by using general detection conditions

1. Fountain solution index test

mainly tests some indexes of fountain solution, including the thickness of fountain solution layer in the blank part of the printing plate, the solubility of fountain solution to ink, etc., which are measured and recorded by the water volume control device

for this test, it is necessary to empty the water supply system of the printing machine, close the water inlet and outlet, and then inject fountain solution into the water supply device, and other printing settings remain unchanged

(1) liquidity test

after starting printing, the machine enters the normal working state after a period of time, and then gradually reduces the flow of fountain solution until the printed matter appears dirty spots, and records its critical value. Then, increase the value set by the wetting roller by 1/4 to ensure that the flow of the fountain solution is above the critical value. If the critical value of the increased wetting roller is more than 70% of the maximum value, it indicates that the fountain solution is unqualified, because it is very necessary to leave 30% room in continuous printing

in this test, the following points should be noted

① in order to achieve ideal printing effect, the blank part of the printing plate must be 0.6 ~ 1.5 μ M wet version liquid film cover

② compared with other types of printing plates such as PS plate, CTP plate requires a thicker fountain liquid film, because its surface properties are different from other printing plates

(2) normal printing test

turn off the wetting system, fill the printing plate with ink, and start printing under the same wetting roller setting. If the printing volume exceeds 50 and still cannot achieve the desired effect, the wetting solution is unqualified. You can also start printing 10 minutes after inking. Similarly, if more than 50 prints are still dirty, it indicates that the wetting effect of the fountain solution is not good

2. Component test of fountain solution

this project includes the content of chemical component test of fountain solution. According to the survey, most printing plants can only measure the following parameters: pH value, buffer capacity, 2-propanol content, surface tension, and water hardness

(1) pH value

the most reasonable pH value (except newspaper printing) should be 4.8 ~ 5.3. P H value can be measured by electronic equipment or p h rod. In view of the equipment conditions of the printing plant, it is more practical to use p h rod, and its reading accuracy is equivalent to that measured by electronic equipment, especially between 4 and 7, and the minimum resolution can reach 0.3

(2) buffer capacity

in order to maintain the stability of continuous printing, the pH value needs to be kept unchanged as much as possible. For this reason, the fountain solution is required to have a buffer capacity between acid and alkali. The stronger the buffer capacity of fountain solution, the longer the time to keep the pH value within a reasonable range. It is feasible for printing plants to adopt simple titration method. The test personnel only need a little training to start work. Add an indicator in the titration process. With the addition of titrant, the indicator will change color, so that the buffer capacity can be measured

(3) 2-propanol content

because the price is relatively expensive and is not conducive to environmental protection, the use of 2-propanol should be minimized. Therefore, it is necessary to measure it accurately. Fogra association suggests using a densimeter to measure the fountain solution, and then determine the concentration of 2-propanol according to the lookup table corresponding to the density (Note: the lookup table data can also be obtained through your own test)

(4) surface tension

because the control of wetting in printing is relatively rough, the surface tension test is used in this test. Drop a drop of fountain solution on the blank part of the printing plate (not the graphic part) without glue, and then use a magnifying glass to observe the spread of the fountain solution on the printing plate. If the fountain solution does not expand around, it means that the surface tension is too high. If the fountain solution expands around rapidly, it means that the surface tension is low enough to ensure that the blank part of the printing plate is fully wetted. The blank part of the printing plate without glue is used as the basis for the test, and the test must be started immediately after the printing plate is washed. It should be noted that this test can only provide a rough measurement of the printability of fountain solution, and cannot cover the emulsifying ability of ink and dynamic surface tension

(5) hardness of water

using water with higher hardness will lead to calcium precipitation, which will increase the friction of the inking system. Using carbonic acid to adjust the pH value of fountain solution will aggravate this situation. Therefore, after correcting the pH value with carbonic acid, the salt in the water should be removed as soon as possible. At the same time, when printing with coated paper, the calcium compound in the fountain solution will also increase, so it is very important to control the hardness in the whole process

can be determined by simple titration test, because the base can combine with nitroethane fatty acid to form a very stable compound, and this reaction can be observed through the indicator

cleaning agents

in order to reduce the use of highly volatile cleaning agents in offset printing and reduce the loss of cleaning agents to printing machinery, a spontaneous agreement aimed at reducing the use of volatile substances in offset printing came into being. This agreement was jointly initiated by many printing machinery manufacturers, Fogra Association, printing and paper industry insurance association, German Printing Association and Ig media, and was certified by Fogra Association

1. Certification standard

all organizational departments involved in the formulation of certification standards will incorporate this testing certification into the safety engineering and environmental protection standards formulated by the current industry and various regions, and negotiate the standards for specifying the relevant parameters of cleaning agents

2. The certification test items

include:

(1) resistance of rubber materials (ink roller and printing blanket)

(2) resistance of mechanical paint, pipes and seals after contacting with cleaning agent

(3) resistance of printing plate

(4) solubility and emulsifying properties of cleaning agent

(5) water quality and solvent-free test in soluble detergent

(6) Baldwin test needs to test the solubility of acetone and nonpolar minerals or vegetable oil in the ink. These emulsions will be mixed with 1:9 (1 cleaning agent, 9 water, solvent or grease), 1:1 and 9:1 respectively in the test, and the total test time is 24 hours. During this time, any stage such as decomposition will be recorded. You should also carefully check whether there is obvious viscosity and sediment formation, of course, these are not allowed to happen

(7) unsaturated substance test. The iodine content in animal oil and vegetable oil is measured according to iso/din 3961 (test of iodine in animal oil and vegetable oil). The maximum allowable iodine content is 20

(8) chemical parameter test. The chemical parameters of cleaning agent include flash point, viscosity, temperature stability, residue and solvent stability, etc

(9) tests for cleaning equipment manufacturers

for cleaning equipment manufacturers, additional tests on the water content of the cleaning agent and the corrosion degree of brass are required

the maximum water content of cleaning agent should not exceed 0.1%

to test its corrosiveness to brass, 11g of brass debris (cuz n39p B3) is completely immersed in 80ml of cleaning agent and placed at 50 ℃ for 12 hours. Note that brass should be cleaned with acetone solution before this. In addition, it is also necessary to prepare a cleaning solution without brass debris in order to compare and test whether the reaction comes from the action between brass debris and cleaning agent. Place brass chips and cleaning agents in Petri dishes with lids to reduce evaporation, while maintaining air circulation. If there is a reaction between the brass debris and the cleaning agent, such as the change of brass color or the turbidity or precipitation of the cleaning agent, the cleaning agent must not contain secondary amines and amino compounds

after the test, Fogra Association will submit the final report of relevant mechanical test results, and the manufacturer will decide whether the product is suitable for the printing machine or cleaning system with high accuracy and high yield based on the test report. If the test is successful, the Fogra Association will issue its letter of authorization to the relevant machinery manufacturer and provide proof of approval of the verification results

with the development of technology, printing accessories in the future will not only focus on utility, but also inject the concept of environmental protection and applicability, and the Fogra association is constantly improving its technical level in response to this concept. Obtaining the f o g r a certification means not only obtaining a special honor, but also the recognition of products, which will also enable more and more enterprises to continuously improve product quality in order to join them, and finally promote the common progress of the whole industry

source: business information of printing materials in China