Storage stability of the hottest water-based gravu

Storage stability of water-based gravure printing inks

after the ink leaves the factory, it is often time before it can be used on the machine. Therefore, the storage stability of ink includes the stability of resin in the system, the stability of pigment (if there is no precipitation) The stability of rheological properties (such as viscosity should be consistent with that when leaving the factory as far as possible) and gloss are important factors that must be considered when developing ink

from the perspective of the composition of ink, the stability of ink is determined by the following three factors:

(1) the nature of resin

(2) dosage of neutralizer

(3) types of auxiliary solvents

(4) quality of pigments

1. Effect of resin on storage stability

the effect of raw resin with different structure on ink viscosity with the lapse of storage time can be divided into three categories:

a, ink viscosity increases almost linearly with the lapse of storage time

b, with the passage of time, the ink viscosity increases at the beginning, and decreases after the maximum

c, with the passage of time, the viscosity of ink basically remains unchanged

among them, class C has a certain elasticity, high strength and wear resistance, and good insulation performance. Therefore, it has been increasingly used in the construction industry. The viscosity situation is expected to be achieved, which needs to be studied through experiments. 6. The curve can be re analyzed and the formula can be solved

in these three cases, the pH value decreased from the initial 8.6 to 7.4~7.9. When stored for a long time, the resin appears turbid or even precipitated in these cases, resulting in the separation of the resin and the solution, which needs to be avoided

2. Relationship between stability and neutralizer dosage

the storage stability of ink is closely related to the amount of neutralizer. The following table shows the relationship between the pH value of ink and the storage time and the amount of amine

neutralization degree of water-based coating pH storage time (days)

84% 7.4 6

105% 8.8 12

126% 9.3 12

it can be seen from the above table that slightly excessive neutralization can obtain better storage stability

if amine also acts as an auxiliary solvent, the separation of binder from the solution will be greatly slowed down. For example, dimethylaminoethanol has a good effect

3. Relationship between stability and auxiliary solvent

the storage and viscosity stability of ink are also closely related to the amount and properties of auxiliary solvent. The auxiliary solvent is not only beneficial to the dilution property as mentioned above, but also can effectively improve the storage stability. The following table shows the relationship between the viscosity of ink and the storage time (60 ℃) and the properties of auxiliary solvent

auxiliary solvent ethylene glycol monoethyl ether isopropyl ethylene glycol monobutyl ether butanol

viscosity increase/pa.s 45450.50 0.5

time/d 4141610

from the above table, it can be seen that ethylene glycol monoethyl ether and isopropyl ethylene glycol are not very ideal. The viscosity of ink is significantly higher with the passage of storage time. Who was China's real economy crushed by? L, while butanol and ethylene glycol monobutyl ether have better effects

source: cigarette packet ink information