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Home Print Technology Kỹ Thuật In Solution To Moisture And Additives In The Offset

Solution To Moisture And Additives In The Offset

Offset refers to in (wet) is said to be the solution to moisture, an important factor in the 3rd in Offset. The balance of water would result in both good and regular Palet paper. To ensure the problem, ask the first solution to moisture (DDLA) to optimize both the composition and physical properties, its chemical. This article would discuss about double what DDLA.

 

1. Solution to moisture and additives:
DDLA in the ideal case hardness of water from 8 ° dH to 12 ° dH (German standard, the following will specify) and pH from 4.8 to 5.5.
In addition, temperature also plays DDLA an important role, allowing about 10 ° C-> 15 ° C. A worker in what must be said: The temperature is too low will lead to particle deposition on DDLA pipes and gutters DDLA, thereby leading to a granular DDLA to the print and rubber.  Figure below describes the play as seed:
Additives is a complex system of substances from different components, it is necessary for the formation of emulsions in the optimal (in the wet offset printing, ink as the paper and lots of rubber is not as pure the tofu because it contains a cartridge of 10 to 30% DDLA), needed to create the link surface (here mean surface tension). Additives is also a factor to adjust the pH of DDLA, we stop rust on the clay in .....
Reason different water quality should use quality as well as quantitative in DDLA also different, depending on the requirements of the manufacturer.

2. Agent platform: Water

We know that water in nature is not completely pure and that the impurities in the minerals, bacteria ... For workers in, water is the main ingredient in DDLA. To assess the country, people often rely on the hardness of it. Which the hardness of water depends on the concentration of Calcium and Magnesium in the water.
Before DDLA phase, the hardness of water must be determined, since the phase DDLA can not determine the quality content to add. Hardness of water is measured by a test strip.
Part of the buildings will lead to some problems in the in as:
Lots of squid ink ... no need to click on.
Closed trapped on rubber sheets.
Impact of pH and makes it varies, not stable.
  Also, too much chloride, sulfate or nitrate ions will lead to the risk of corrosion.
  Total hardness of water will be measured by a test strip. Measurements is quite simple: Views on the test strip in a second, get out, wait about 2 minutes and read the data.

3. PH:

"pH" is derived from Latin (Hydrogenii Potentia), is a logarith of the H + ion concentration in solution.
  pH is a measurement value indicator of acid, base (alkali) in liquid solution. A fluid pH = 5 is 10 times higher acidity of liquids other pH = 6.Often people use the dedicated neutral powder chemical impact from the outside to the solution, which also apply in DDLA.
  However, pH measurements do not mean much to assess the quality DDLA, it is only necessary when phase DDLA phase additives how. DDLA quality will be evaluated through its electrical conductivity.

4. Electrical conductivity [μS / cm]:

Purified water is not conductive, but impurities in DDLA increase transmission capacity in the current DDLA and therefore subject to water and additives that electrical conductivity of DDLA also different.
Temperature and alcohol also cause impacts on electric conductivity. The more alcohol Iso propanol (IPA) as the electrical conductivity decreases.
Measured electrical conductivity value should be determined for each new DDLA will replace the old DDLA available in the gutters. When conductivity reaches the threshold of 1000 μS / cm is also the time to consider changing DDLA. To avoid problems when printing, it is often recommended instead DDLA after 14 days, the filters can be extended using time DDLA but also only one time solution.

5. Associated with the surface in:

Surface tension of water will reduce the impact of Gummi Arabic, Glycol, Glycerin or alcohol. Type substances used in the tables are the manufacturer's instructions.
Alcohol, in particular IPA, a substance linked surface well, it's a possibility of increasing the viscosity of DDLA besides reducing surface tension, supports the creation of membrane system-level moisture DDLA , through which the level of moisture in the air conditioner will be more. IPA alcohol evaporates quickly, so the ink is dry place faster. Evaporation of alcohol also has other meanings: Units are to be cooled by vaporising alcohol. Using alcohol also works to prevent the formation of bubbles on the surface DDLA network.
Check Alcohol: Alcoholic used in print to pure, there is a method of testing is quite simple Heidelberg presented as follows:
  "Get the glass clean for a water and alcohol into the cup. To saddle for 30 to 45 minutes, then the solution must be transparent if the solution becomes opaque, the alcohol is not used"
Measurement of alcohol in DDLA:
Instruments measured the rate of fluid (Araometer - Hydrometer) in DDLA be free to move in the liquid in the glass test tube. The liquid and the equipment that may not have air bubbles. Data on liquid throughout will read from the bottom. Value measurement calculated by% volume. Temperatures will be measured, along with the rate of% volume of liquids to calculate the concentration of IPA in DDLA.  However, this value is only a reference calculation based on the chart below to have derived real value for the concentration of IPA in DDLA:
For example, the measured value of 9.5% but the actual concentration of IPA is 14%.
Measuring alcohol in DDLA usually based on volume DDLA own, it depends not only on its own volume of IPA, but also influenced by temperature, additives added and its level of impurities.

6. The disadvantages of alcohol:

IPA increases the phenomenon of ghosts (Schablonieren), because DDLA adverse impact in the emulsion.

IPA can not have lots of squid ink, misleading the ink level, especially when water use is high hardness. Calcium is the reason for the IPA DDLA was dissolved, rub the print, will DDLA Calcium in crystalline, close to lots of local squid, making lots of ink can not pass through the scrub to the printed version.

IPA can do too much binder in the ink is reduce, the level of the ink off the ball, especially pigment ink used heavy metals.

IPA impact on paper, including clots on rubber sheets.

IPA is compounds volatile, the IPA can be little adverse impact on air environment and human health. To think "the more they will be better, no worker in pure IPA phase will exceed the dose than necessary for printing. Reasons and environmental health, alcohol IPA should be checked by two weeks.

  Note, the above information is only useful for its Heidelberg Offset printers, printers for other information on the only valid reference.

 

 

 

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