Types and usage of the most popular offset printin

2022-10-03
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Types and usage of printing offset ink additives

I. viscosity and fluidity adjusters

there are many kinds of additives, which are used to adjust the fluidity and viscosity of ink, mainly including inking oil and adhesive remover. Traditional inking oil mainly includes seven varieties from No. 0 oil (i.e. extra oil) to No. 6 oil. The viscosity is the largest in No. 0 oil and decreases in turn from No. 6 oil, but some are not commonly used. Of course, in addition, there are other varieties of inking oil

mainly introduces the following commonly used:

1. No. 6 oil

it is one of the traditional common ink auxiliaries, which is mainly used to increase the fluidity of the ink, but also reduce the viscosity of the ink. The amount of resin type ink is generally less than 5%. The dryness and gloss of the ink will be reduced after adding

2. No. 0 inking oil (also known as foreign oil)

inking oil has the highest viscosity, almost no fluidity, and is a transparent elastic fluid with high viscosity. It is mainly used to increase the viscosity of the ink, reduce the degree of emulsification, adjust the viscosity of the front and rear color group ink, make the first printing ink slightly sticky, and improve the transfer performance of the ink. The dosage is generally below 5%, so as not to affect the dryness

3. the viscosity of resin inking oil

is greater than that of No. 6 oil. It is used to adjust the fluidity of the ink, but does not affect the viscosity of the ink. The dosage is generally about 3%. The addition of the blending oil does not affect the gloss and adhesion fastness of the ink, and has little effect on the dryness

4. The viscosity vibration test of diluent

has attracted attention from all walks of life. It is smaller than No. 6 oil, which can increase the fluidity of ink and reduce viscosity. It has the characteristics of small dosage but obvious effect. The dosage is generally less than 3%, which basically does not affect the gloss and dryness of the ink

5. High boiling point kerosene (aviation kerosene)

the boiling point is 250 ~ 290 ℃, which is an excellent ink auxiliary agent. It has good miscibility with the ink, and can be directly added to the ink. It can reduce the viscosity of the ink and increase the fluidity to a certain extent. It also has the characteristics of less dosage and obvious effect. The dosage is generally 1% - 2%, which can meet the requirements. Of course, it can also be increased or decreased as appropriate. The addition will not affect the gloss and adhesion of the ink, and has little effect on the dryness

6. Adhesive remover (also known as adhesive remover)

is paste like, and it is also one of the traditional common ink auxiliaries. It has the function of reducing the viscosity of ink but basically not increasing the fluidity. It can be used in combination with resin inking oil, No. 6 oil, etc. or it can be used alone. The dosage is generally below 5%, too much is easy to cause dirty version and reduce the gloss, dryness and adhesion of the ink. The amount of printing that needs to be covered with film should be strictly controlled, otherwise it will cause blistering and poor adhesion

7. ink improver (also known as ink additive)

is a new ink auxiliary agent, which is in the form of paste. It is very miscible with ink and will not dilute the ink color when added to the ink. It can not only reduce the viscosity of the ink, but also increase the fluidity. The dosage is usually between 3% and 8%, which can also be increased or decreased as appropriate. Under normal circumstances, it will not affect the dryness of the ink, but excessive will reduce the gloss and adhesion of the ink

8. Anti drying agent

is also called antioxidant. When some pigments with strong drying performance are used in the ink formula, such as iron yellow, chrome yellow, etc., film formation will occur during rolling, so it is difficult to roll fine; When the ink is stored, if the surface part is in contact with air, it will be oxidized and crusted, or even dried, resulting in the inability of the ink to use; In the printing process, the ink will also have oxide scaling and drying on the printing machine. Therefore, adding an appropriate amount of anti drying agent to the ink can delay the oxidative polymerization process of dry oil. Anti drying agents are strong reducing agents, such as hydroquinone and catechol, which can be preferentially oxidized to delay the oxidation process of dry oil. They are often used as polymerization inhibitors in the polymerization process of high molecular substances, because they are easy to react with free radicals to form stable compounds, which prevents the chain growth reaction of free radicals

Second, driers

are used to adjust the dryness of inks. There are mainly two kinds:

1. Desiccant

also known as drier, is a very important type of auxiliary agent in ink. It is the catalyst of dry vegetable oil oxidation polymerization conjunctiva. In high gloss inks, due to the high content of resin, in order to accelerate its complete drying, we must rely on desiccants

, radiation, water-based, additives, pigment desiccants are organic acid soaps of cobalt, manganese, lead and other metals. In high gloss inks, cobalt and manganese organic acid soaps are mainly used. They are all oxidation driers, which have very strong driability and can make the ink surface dry quickly and evenly. The function of desiccant is to shorten the induction period, accelerate oxidation and promote polymerization

2. White drying oil

is a mixed drying agent, which can dry the inner layer and surface of the ink at the same time. It can be used alone or in combination with red drying oil. Strong drying performance, and can improve the gloss of the printing to a certain extent. The dosage should be less than 5% and no more than 10%. Excessive addition will lead to problems such as not drying, dirty version, dry cots, etc. in case of such failures, you can reduce the amount of white drying oil (less than 3%), and add a small amount of red drying oil (about 0.5%). It should be noted that white dry oil contains heavy metal lead, which is harmful to human body, so it cannot be used to print prints with hygienic requirements such as food packaging. In case of such prints, red dry oil or mixed desiccant can be used instead

3. Red drying oil

has the characteristics of less dosage and obvious effect, which can quickly dry the conjunctiva on the surface of the ink and improve the gloss of the print. It is usually used together with white dry oil, and sometimes it can also be used alone. The dosage is generally about 1%. Excessive use is easy to produce the phenomenon of "dry rubber roller". In "dry overprint" (that is, wet press dry printing), the first two colors should not be used or used as little as possible to avoid the crystallization of the ink layer. In addition, although the red dry oil is dark red or purplish red, it generally will not affect the color tone of the ink because it is transparent and the amount is small. Even yellow, white and other light colored inks can be used according to the newly revised "titanium dioxide industry access conditions"

4. mixed desiccant

in addition to the above two desiccants, another new advanced desiccant is a product recently developed by ink manufacturers, which belongs to mixed desiccant. It can promote the comprehensive and rapid drying of the ink from the outside to the inside, and can improve the gloss of the print and the adhesion fastness of the ink to a certain extent. Because it does not contain heavy metals harmful to human body, it can be used instead of white dry oil for printing food packaging and other printing with health requirements. Generally, it can be used alone to meet the requirements. If there are no sanitary requirements for the printed parts, it can also be used with white dry oil. When used alone, the dosage is generally controlled below 2%. In addition, the mixed desiccant itself is dark red or purplish red, but because it is transparent and the amount is small, it generally will not affect the tone of the ink like red drying oil

III. diluent (diluted ink)

auxiliary agents used to prepare light color inks, mainly including white ink, diluent, etc

1. White ink

is a diluent commonly used to prepare light color inks. The light color inks prepared with it have good hiding power, and the ink color is white, thick, and has a strong powder texture, which has an effect unmatched by other diluents. However, due to the large proportion of white ink pigments and coarse particles, the printability is not very ideal. Sometimes, it is prone to failures such as poor ink transmission and transfer. The adhesion of ink has been derived from the original single screw, and the twin screw and multi screw are also relatively low. The printing that needs to be covered with film sometimes has the disadvantage of poor adhesion. To avoid such failures, you can use brightening paste or diluent. For the printing pieces that must use white ink as diluent, it is recommended to choose white ink with better quality, or use both white ink and gloss paste together, which can not only maintain the unique quality of white ink, but also improve the printing suitability of ink and improve the gloss and adhesion of printing pieces

2. Diluent (also known as diluent)

is a transparent diluent, which has good miscibility with ink. It can only dilute the color when added to the ink without affecting the tone of the original ink. The drying property and gloss of low-grade diluent are slightly poor, so desiccant must be added as appropriate. The higher grade diluent has the characteristics of high gloss, good printability and moderate dryness, so it is usually unnecessary to use desiccant. Generally, it can be used alone or in combination with white ink

3. Gloss paste

is an excellent ink diluent. In addition to the same advantages as diluent, it also has higher transparency and gloss, better printability and dryness. In addition to being used as a diluent, sometimes it can also be used for the surface polishing of printed parts. It has good gloss, but its friction resistance is not high

4. Anti fouling agent

is also called anti fouling agent. When printing, the ink on the printed matter sometimes gets dirty on the back of another printed matter; When the printed matter is piled together, it will also stick together. For high gloss ink, its drying time is slow, and it is easier to rub dirty. In printing, powder spraying is mostly used to prevent dirt

IV. offset gloss oil

is a kind of printing gloss oil, which can be directly applied on the surface of the print by using the printing machine. The selection and coating of the electronic tensile testing machine in the scheme of establishing all the soft packaging implementation rooms on the surface of the print. It has excellent transparency, gloss, friction resistance, water resistance and solvent resistance. It is mainly used for polishing the surface of printing, and sometimes it can also be used as diluent. Diluted ink has high gloss and friction resistance and good printability. However, gloss oil will reduce the service life of ink rollers and blanket, so it should be avoided as a diluent as far as possible, and it is better to use gloss paste. Offset printing gloss oil is divided into gloss type and matte type, which should be distinguished when using

the above is only a common part of ink auxiliaries. In addition, there are anti drying agents, anti adhesion agents, friction agents, etc., which will not be repeated here

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