The all-in-one machine has many models, and different models are equipped with corresponding ink packaging containers, but all inks are water-in-oil emulsions in composition. The use of the integrated machine is based on fast and low cost, and the ink used has the characteristics of low cost, environmental protection, stability, and quick drying. One machine ink and other inks are basically the same composition, but has its own characteristics: the ink consists of oil phase and water phase, which belongs to the penetration volatile dry ink. For the characteristics of the all-in-one machine, the ink must satisfy the following conditions: the internal structure rationality of the various components in the formula; the suitability of the printing (inks of different natures used in different models); the practicality of printing graphics (blackness) , quick drying, etc.).
1, oil phase
The oil phase consists of binders, pigments, auxiliaries, emulsifiers, and the like.
(1) Mineral oil, vegetable oil
Mineral oil, mainly distillates with petroleum distillates ranging from 270°C to 310°C (about 15 to 18 alkanes), uses this mineral oil as a solvent for the ability to dissolve the resin is quite strong, and solvent release is also fast. The wetting of pigment particles is also excellent. Mineral oil should have no peculiar smell, strong paper permeability, good resin solubility and release properties, and small viscosity-temperature denaturation. The main technical indicators are: color, odor, density, flash point, viscosity, pour point, acid value, aniline point ), ring analysis, and viscosity index. The color is generally light yellow, white, odorous is the depth of refining is not enough; density is generally 0.88 ~ 0.93g/cm3; flash point above 170 °C; kinematic viscosity at 25 ~ 30mm2 / s and 425 ~ 435mm2/s; The point is generally below -15°C; the aniline point should be between aromatic hydrocarbons and paraffins. If it is too high, the oil contains high amounts of paraffins and is too low, the oil contains high aromatic hydrocarbons, and the kinematic viscosity is 25～ The aniline point of 30mm2/s is approximately 76°C, the aniline point of kinematic viscosity at 425-435mm2/s is approximately 96°C, and the carbon ring analysis indicates that the naphthenic carbon (CN%) is greater than 40% and aromatic carbon (CA%). For less than 15%, the paraffin carbon (CP%) is generally 40% to 55%; the viscosity index (VI) means the viscosity of the oil with temperature changes, the greater the viscosity index, the viscosity of the oil changes with temperature The smaller the change is, the viscosity index for kinematic viscosity at 25 to 30 mm2/s is about 2.5, and the viscosity index for kinematic viscosity at 425 to 435 mm2/s is about 35. Mineral oil available in the market can be 270#, 280#, 32#. Vegetable oil can be selected from soybean oil, linseed oil, sesame oil, and tung oil. In general, several kinds of oil are mixed in the ink, so that the advantages can be complemented and the best effect can be achieved.
(2) Resin
The resin is an integral part of the ink film and is attached to the paper in a three-dimensional network structure to form a rigid ink film while giving the ink system an appropriate viscosity. The substrate for the ink of the integrated machine is paper, and the resin may be selected from the group consisting of alkyd resin with long oil content, calcified rosin resin, rosin modified phenolic resin, low terpene phenol resin, petroleum resin, C9 resin, and the like. It is preferable to use two or more kinds of resins in combination, and the proportion should be paid attention to the overall ink property of the ink. Also pay attention to the compatibility of the oil and the resin, the wetting ability and gloss of the resin to the pigment. The resin is easily precipitated and easily oxidized in the air. The resin on the market is difficult to meet the requirements of all-in-one inks. In general, all-in-one ink manufacturers are chemically modifying the resin to meet the overall requirements of the ink and improve its overall performance. .
(3) Emulsifiers
Generally oil and water are immiscible. To obtain a relatively stable emulsion, an emulsifier must be added to reduce the surface tension at the interface. Emulsifiers generally use non-ionic surfactants. The surfactants are composed of hydrophilic polar groups and lipophilic non-polar groups on the molecular structure. The choice of HLB value (hydrophilic-lipophilic balance)=2.5- The surfactant of 5 forms a water-dispersed (W/O) type dispersion system in water dispersed in oil. The selection of the emulsifier is the most critical component of the entire ink system and it is the decisive factor for the stability of the various aspects of the ink. It is the link between the water phase and the oil phase, which plays a role in the bridge and is of vital importance. The dosage is 3 to 4%.
(4) Antioxidants
In the structure of mineral oils, vegetable oils, and resins, there are many unsaturated double bonds that are not saturated and are easily oxidized by oxygen in the air and cross-linked to dryness. After adding some kind of strong reducing agent, they cause oxygen, heat, and sunlight exposure. The aging and crusts have a protective effect and can preferentially contact oxygen to slow the drying process. Optional: 2246, DNP, 4010NA, ANP, etc.
(5) Pigments
One machine ink, mainly black ink and red ink, black is mainly carbon black, red is mainly. The carbon blacks used in inks are mainly CHANNEL blacks and furnace blacks, of which the furnace method is the main production method, with high blackness, low cost, and many stages. However, its surface activity is low and surface treatment (surface oxidation) is required to increase the surface activity. The grooved carbon black is best used in ink because of its high surface activity and high brightness. However, due to its low production capacity, prices are relatively high. Of all the pigments, carbon black is the most difficult to grind, and it is quite difficult to choose. The main technical indicators of carbon black: specific surface area, the larger the specific surface area, the higher the blackness, easy to infiltrate, easy to disperse but easy to aggregate, particle size, small particle size, large specific surface area, darker but easy to appear red phase, particle size Larger is easier to disperse the blue phase; Absorption value (DBP absorption value), its value is high, carbon black structure is high, viscosity is high, coloring power is low, and gloss is low; coloring power is the ability of carbon black to dye white body; The component is the content of the oxygen-containing functional group (hydroxyl, ester, carboxyl, etc.) adsorbed on the surface of carbon black. It is the performance of surface chemical properties of carbon black, and has a correlation with the pH value. The hydrophobicity of the surface treatment is enhanced, and the absorption is increased. Reduced moisture; PH value, the general furnace carbon black is alkaline, only after surface treatment its value is between 3 and 5 and the volatile matter is high. To screen carbon black, we need to start with the entire ink system, that is, which of the several indicators are decisive and comprehensively considered in order to achieve the best results. Foreign carbon black manufacturers include Cabot, Dugussu, Mitsubishi of Japan, and DIC of Japan; domestic companies include Shanghai Coking, Liaoning Fushun and Dandong, Henan Qichang, Tianjin Dagang, and Fujian Nanping. . The ink of the integrated machine requires fineness of fineness, fineness of 10um or less, and hue of reddish-brown phase. Blue paint is required to add color to achieve a darker and softer feeling from the naked eye. Phthalocyanine blue with a carbon black content of about 7% is generally added. Red pigments are mainly gold red, red, etc. The red pigment has high moisture absorption, and should pay attention to this point in use. The saturated ink saturation of the ink is very low and the surface is dull.
(6) Dispersing agents
Of all the pigments, carbon black is the most difficult to grind, the hardest to disperse, and it tends to accumulate back and coarse after dispersion. The special hyperdispersants for carbon black include alkyl amines, polyesters, polycarboxylic acids, phosphate esters, alcohol amine salts and alkyd resins. Adding a small amount of dispersant can double the dispersion of carbon black.
2, the aqueous phase
The aqueous phase consists of: pure water, water absorbent, water retaining agent (anti-drying agent, moisturizer, antifreeze), and anti-corrosion and anti-mildew agent. The pH of the aqueous phase is considered as one of the most critical factors in controlling the production process. Low pH results in increased viscosity of aqueous ink, high pH, ​​low viscosity, slow drying, poor water resistance, and easy separation of oil and water.
(1) pure water
The water quality requirement is neutral deionized water with a conductivity of 15us/cm2 or less.
(2) Water Absorbent
There are gum arabic, cellulose, clay, acrylic resin and so on. Its role is very large, with thickening, emulsification, stability, anti-settling and filming and so on. Its mechanism: It has a strong water absorption capacity, which promotes its large volume expansion and increases the viscosity of the emulsion.
(3) Water retaining agent (anti-drying agent, moisturizer)
Water evaporates and high-boiling solvents are added. Ethylene glycol, glycerin (high boiling point, low freezing point and water miscibility) are generally used as wetting enhancers, moisturizers, and emulsifiers in ink systems. Because the interfacial tension between water and oil phase is relatively large, this high boiling point solvent can effectively reduce the surface tension at the phase interface, increase the contact angle of the ink to the paper, and thus achieve the spreading effect; it can effectively prevent the ink from being exposed to low temperatures. Under the freeze, it plays a moisturizing trend.
(4) Antiseptic and anti-mold agent
Anti-corrosion and anti-mold agents prevent the growth of bacterial mold in the water phase and prevent the ink from smelling and deteriorating.
Reprinted from: Printing and Packaging Business Network