Third, anti-gelling agent
The gelation, thickening, and lumping of the ink system are generally caused by the following factors: The salt-based pigments react with soaps that have higher acid values ​​or free fatty acids. Or because of the agglomeration and gelation of the binder material, the ink system absorbs water, the pigment content in the ink system is too high, the used binder material is not proper, and miscibility of the resin and the oil in the binder material is poor. In a high molecular polymer system, since the pigment absorbs the acid-soluble structure, it also promotes gelation and the like.
Due to too thick, or due to the high degree of polymerization of the link material formed by the gel, you can add appropriate dilution, soluble substances. (aliphatic hydrocarbons, esters, ketones, etc.) to overcome.
For the type of gel that reacts to soap, rosin acid (rosin or calcium rosin dissolved in linseed oil), linolenic fatty acid, maleic acid, or high acid maleic anhydride resin (dissolved in linen) can be added. In the oil) equal high acid content to dissolve the glue. A more prudent approach is to use the metal naphthenate as a deblocking agent because the side effects of this material are small. Such as adding more fatty acids, in the printing may cause ink from the dirty, hydrophilic, dry slow and other ills, and the metal naphthenate is more reliable. When manufacturing inks, it is sometimes the case that some aluminum naphthalate is added to increase the stability of the ink.
The substances that can restore the rheological properties of colloidal inks can be collectively referred to as inverse gelling agents.
The amount of anti-gelatinizer added is not more than 5%.
The gelled ink is best used promptly after adding anti-gelling agent to the gel. Otherwise, it is still possible to return the gel.
IV. Withdrawal
Dilution agents are also known as diluting agents. Their function is to reduce the color intensity of the ink, but does not substantially change the viscosity and other rheological properties of the ink, printing properties, etc.
The white oil, transparent oil (Viley oil) in the plastic and printing inks, the varnish, diluting agent in the gravure ink, and some transparent and translucent base inks play these roles.
White oil is used for printing with light color (commonly known as small color), and its function is mainly to dilute the ink. Of course, it may also bring about some other changes in the characteristics.
Formula example:
Ink Adjuster(#4)16%
Wax 38%
Aluminium hydroxide 29%
Barium sulphate 15%
Titanium dioxide 2%
The ground oil consists of 15% ground wax and 85% of No. 4 varnish.
In the white oil system, there is also an emulsified water-white oil, which is obtained by adding sodium carbonate solution to the vegetable oil-type linker milk (soap) and adding magnesium carbonate, aluminum hydroxide, wax, ester and other substances. Rolled. The advantage is low cost, but its disadvantages are more, such as instability, poor printing performance. With the development of emulsification technology, it may also be improved and improved.
Transparent oil (commonly known as Weili oil) is a slurry-like transparent body made of aluminum hydroxide and dried vegetable oil binder. It is generally thought that adding it to the ink will increase the brilliance of the ink, but in fact it is mainly responsible for the lightening effect. Dilute the ink when diluting the ink with the linking material alone, and dilute it with transparent oil without this disadvantage.
Formula example
Ink Adjuster(#3)l0%
Diverted oil (#4) 41%
Refining oil (#6) 4%
Aluminum hydroxide 45%
Recently, transparent oils have been manufactured using synthetic resin-type binders and stabilized aluminum hydroxide (or some transparent calcium carbonate). This type of transparent oil has better drying performance and gloss.
Transparent oils are sometimes used as varnish because of their good transparency. Of course, it is different from the varnish.
Transparent oil can also be said to be a colorless ink with excellent printing properties.
Transparent oil transparency indicator is one of its main quality indicators. In general, when the transparent oil has a water content of about 20%, its transparency is good. If the quality of aluminum hydroxide meets the requirements (water content should generally be around 25%), the temperature of the three-roller can be controlled during rolling to control the moisture content of the transparent oil to ensure its transparency.
In the factories that produce aluminum hydroxide by themselves, transparent water can be produced by using the squeeze water method if conditions permit. In this production method, the water-squeezing base ink of aluminum hydroxide is first rolled twice on a three-roll mill, and after rolling, the ink is put again.
In an open kettle with steam jacket, it is dehydrated and transparent under constant stirring at a temperature higher than 100°C. The dehydration condition should generally be slightly overdose to ensure transparency after cooling.