Composition and Cleaning Principles of Ink Cleaners (2)

(b) Composition of ink cleaners

Ink cleaner consists mainly of the following components:

1. Hydrocarbons

In cleaners, the content of hydrocarbons is more than 50%, and hydrocarbons are divided into aliphatic hydrocarbons and aromatic hydrocarbons according to the molecular structure. They have the following characteristics:

(1) Aliphatic hydrocarbons: The chain structure containing carbon molecules in the molecule has a good dissolving effect on the ink and cannot be dissolved in water. It does not harm the rubber, the human body and the environment.

(2) Aromatic hydrocarbons: The molecule contains a cyclic chain structure of carbon molecules, which has a good solubility in ink. However, it will cause swelling of the rubber polymer and adversely affect the human nervous system. Long-term use may lead to cancerous lesions.

2. Emulsifier

Ink cleaners must contain emulsifiers that have the following properties: They promote the mixing of oil and water and produce emulsification. Generally flash point cleaners contain emulsifiers; they do not cause residual chemicals on the rollers and blankets.

3. Anti-corrosion agent

Because the cleaner needs to be cleaned with water, the anti-corrosion agent has the effect of preventing water corrosion.

High-quality ink cleaners generally consist of two organic solvents with different boiling points, rubber antioxidants, and surfactants that can form stable water-in-oil emulsions.

(III) Technical Specifications of Ink Cleaners

In general, the technical indicators for measuring high-quality ink cleaners are:

1. Fragrance-free

Aromatic compounds have a strong ability to clean inks, but aromatic compounds have a number of adverse effects on printing, so the new ink cleaners should not contain aromatic compounds.

The adverse effects of aromatic compounds on printing are:

(1) Fragrances can cause rubber swelling, affect printing pressure, and can easily cause print quality problems.

(2) Does not meet environmental standards and human health standards.

Figure 2 shows the effect of aromatics on the printing roller during the printing process.

2. Based on vegetable oil

Ink cleaners should be based on vegetable oils, not mineral oils.

3. High flash point characteristics

At present, the flash point of international high-quality ink cleaners is above 55°C. In the cleaning process of thermosetting inks, the flash point of cleaners is as high as 100°C or more. The flash point of the cleaner must be higher than the minimum temperature in the print channel to meet the safety standards of the workshop. The flash point of the cleaner in general printing should be above 55°C. In the printing of UV ink, the flash point of the cleaner should be Above 70°C.

(d) International standards for ink cleaners

Regarding the standards of ink cleaners, there were international regulations in 1995, as follows:

(1) All new machines (produced later in the Convention) should be able to apply to normal working production. When using cleaners with a flash point of 55°C or higher, the machine's production capacity is still within the normal range.

(2) Cleaners with a flash point below 21 °C cannot be supplied or used for the cleaning of printing rollers and blankets.

(3) Cleaning agents with flash points between 21 and 55 °C, which are allowed before the date of this Convention when there is no other choice for technical reasons, are not allowed on new machines.

(4) Manufacturers, suppliers, printers, employees, and authorities will negotiate alternatives for solvents, including the use of a high flash point solvent (flash point of 100°C) and vegetable oil type cleaners to replace earlier solvents.

(5) Solvents containing halogenated alkane terpenes (turpentine), n-hexane, imines, or amides must not be supplied and used.

(6) The content of aromatic compounds in the supplied or used solvent should be less than 0.1%.

(7) The toluene or xylene content in the supplied or used solvent should be less than 10%.

(8) The content of hydrocarbons in the supplied or used solvent should be less than 10%.

(9) Infrequently used low flash point materials, such as blanket recovery agents or skinning ink removers that contain methyl ethyl ketone, may continue to be used in small amounts but must be warned and operationally trained in advance.

(10) Suppliers and users of printers, materials, and consumables work together to provide technical support and training with the help of relevant associations to allow users to adapt to new cleaning methods when using high flash point solvents. If necessary, you may also need to replace the blanket and roller.
Quality ink cleaner characteristics

(e) In printability, high-quality ink cleaners have the following performance :

(1) It meets the requirements of environmental protection and health. It does not contain aromatic compounds and its flash point is higher than 55°C.

(2) The ink has good cleaning ability, and the degree of cleaning of organic and inorganic compounds is more than 95%.

(3) Good adaptability to the rubber roller and rubber blanket, and the expansion rate generated is not higher than 2%.

(4) No corrosive effect on printing plates and printing presses.

(5) The main component of auxiliary cleaners should be vegetable oil.

(6) Ink roller auxiliary cleaner

In the printing process, due to the influence of external conditions such as paper, ink and water quality, the cleaning effect of the ink, the chemical adaptability of the printing roller, and the influence of deformation due to chemical factors are increasing. In modern printing, we also use some chemical care products for auxiliary cleaning while using ink cleaners to ensure that the impurities remaining on the rollers are completely removed, and the purpose of smooth printing is finally achieved. These auxiliary cleanings mainly include deep cleaning, enamel removal, rubber reduction, idle protection, and dead ink softening.

1. Deep Cleaning

Mainly in the printing unit to replace the color, ink roller cleaning and maintenance and printing spot color ink when carried out, can significantly reduce downtime. Reduce the number of paper feeds.

2. Calcium removal

The quality of the water supplied to the lithography printing system in different regions is different. The calcium carbonate and other minerals contained in the system are also different. At the same time, the water hardness varies. Under normal circumstances, the rubber roller will absorb calcium carbonate and other minerals, so that the surface of the roller to transfer water, ink, the ability to decline, so the removal of calcium is very necessary.

3. Idling protection

The contact surface of the ink roller will cause permanent damage to the surface of the ink roller in a very short time when it is rotated without ink lubrication. Therefore, when the ink roller is idling, special chemical care products are needed to prevent the ink roller. The idling causes surface damage or excessive heat.

4. Regular cleaning

Long-term printing will cause stubborn hard ink and other impurities inside the rubber, which will cause the glaze and hardness of the surface of the rubber roller to increase. Therefore, the rubber must be thoroughly cleaned and elastically restored.

5. Enamel removal

Due to the accumulation of time, the residual material formed on the rubber surface must be cleaned. (Text: Wang Yongsheng)

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