The influence of the quality of the hottest water

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The influence of water quality on offset printing and its treatment

with the development of printing industry, the society has constantly put forward higher and higher requirements for the quality of printing materials, from printing equipment, printing materials, printing consumables, to the operating skills of operators. This paper will discuss the influence of water quality on printing and the improvement of water from the quality evaluation of offset printing water

1. hardness of water quality

when the hardness of calcium exceeds 200ppm, it will form calcium saponification when it comes into contact with the resin in the ink, and when it comes into contact with acidic solution, it will produce salts such as calcium citrate and calcium phosphate

calcium saponification is lipophilic, which will lead to the deposition of ink in unwanted areas, such as the surface of water roller and water glue pile. Calcium salt has good hydrophilicity, which will hinder the transmission of ink and lead to the deinking of ink roller

in addition, if the calcium ion content in the water exceeds the standard, it will directly affect the service life of the cots and cause crystallization on the surface of the cots

conclusion 1: excellent water will aggravate the emulsification process of ink, lead to the deposition of ink on the waterway, and aggravate the aging of rubber rollers (surface crystallization)

2. the fluctuation of conductivity when entering water

the dynamic surface tension of fountain solution depends on the concentration of fountain solution. The higher the concentration, the lower the surface tension

some commercialized automatic conveying devices can control the concentration of fountain solution in order to achieve a predetermined conductivity. When the conductivity of the influent is too large, it will cause the change of the concentration of the fountain solution, and the result is the imbalance of the oil-water ratio, causing offset printing failure

if the proportion of fountain solution is quantitatively controlled like other units only by solving the problem of recycling, the problem may not be great, but when the conductivity of the supplied water changes greatly, it can still cause the imbalance between oil and water. 1. The portal structure is novel

conclusion 2: when the conductivity of water fluctuates, it will affect the automatic control and detection of fountain solution in the printing process

3. For large companies with multiple branches

some companies have branches in several cities and need to carry out standardized management in order to achieve relatively unified quality. This also puts forward higher requirements for the water quality used. For example, how hard is the water itself in several cities, and how about the impurity rate of water in several cities. These are all issues that must be considered

conclusion 3: when the water quality in different regions is different, it will have a certain impact on the quality standardization of printed matter

through the above analysis, we find that the quality of water itself has an impact on the printing process within a certain range and is used correctly, so the treatment of water is not irrelevant. It is necessary for competent enterprises to treat printing water, and it is necessary for water treatment in areas with poor water quality

water treatment methods:

water treatment methods can be carried out through various channels, such as distillation, softened water treatment, activated carbon filtration, microfiltration, ultrafiltration, reverse osmosis filtration, etc

1. softened water treatment:

use the resin soaked in sodium chloride to filter the water. When the sodium ion that has been combined with the resin meets the calcium, magnesium and manganese ions in the water, it will be replaced by these ions, that is, the sodium ion enters the water and adsorbs the calcium and magnesium plasma to the resin at the same time

this treatment can effectively reduce the hardness of water (that is, reduce the content of calcium and magnesium ions in water), but it is worth noting that since the concentration of ions in water has not changed, the conductivity of water itself has not changed

2. ion removal method

this method uses cation resin exchanger and anion resin exchanger to exchange cation and anion in water respectively. When pressurized water passes through the exchange system, the ions in the water will be adsorbed by the resin, and the hydrogen ions or hydroxyl ions in the resin will be replaced into the water, which will also consume the charged resin. When the resin fails, strong acids and bases can be used to reduce the resin

there are mainly two kinds of equipment for water treatment in this way:

① double bed resin exchange equipment. This kind of equipment usually has two resin containers (yin and Yang)

② mixed type. The anion and cation resin is mixed in a certain proportion and used at the same time. If the mixing proportion is appropriate, the water quality after treatment is very good

3. reverse osmosis method:

under normal circumstances, the diffusion of water is from the place with low concentration to the place with high concentration. Reverse osmosis method is to reverse this process with certain materials and means to make water diffuse from the place with high concentration to the place with low concentration under pressure. Reverse osmosis is a relatively thorough impurity removal technology, which can remove 90 ~ 95% of the impurities in our drinking water under normal circumstances. The commonly used filter materials are cellulose acetate membrane, polyamide membrane and composite membrane

※ attachment: the measurement of water conductivity is a method to characterize the electrolyte content in water. The unit is s, that is, the reciprocal of water resistance. There are also smaller units s. The electric research of the fountain solution required to be used in the printing process produces 3D printing materials with higher performance, and the conductivity is generally 500 ~ 1500 s

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