Application of "two-dimensional ink making method" in packaging printing
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For a long time, the "technical stacking method" which is added and subtracted in the process of packaging printing ink manufacturing and packaging printing, and the "intrinsic viscosity method" which is usually used in ink formulation design (weigh a certain amount of polymer dissolved in different solubility) In the solvent of the parameter, the intrinsic viscosity is measured at a certain temperature, and the obtained maximum intrinsic viscosity system can be determined as the solubility parameter of the polymer is equal to the solubility parameter value of the system) and the "equilibrium swelling method" (at a certain temperature) The crosslinked polymer is swelled in a solvent having different solubility parameters, and when the equilibrium is reached, the degree of swelling and the maximum swell degree are determined, and the solubility parameter of the corresponding solvent system is the polymer. Solubility parameters), these two are relatively simple and intuitive methods for determining the solubility parameters of polymer compounds, and are far from being able to meet the requirements of modern packaging and printing technology.
The "two-dimensional ink making method" described herein is based on the principle that the solubility parameters are the same or similar and can be mutually soluble, to determine whether the resin is dissolved in a solvent or a mixed solvent and the mutual solubility of the ink and the substrate.
The second is to predict the miscibility of the two solvents or inks with the substrate based on the principle that the solubility parameter values are the same or similar and can be mutually soluble.
The third is based on the solubility parameter, it can be estimated that the mutual solubility of two or more resins (the parameters can not be greater than 1.5 above and below) and the adhesion of the substrate.
The fourth is to use the solubility of the resin in the packaging printing ink system in a series of solvents with known solubility parameters, and the range of solubility parameters of the resin and the substrate can be determined experimentally.
According to the solubility parameter, we can judge the solvent resistance of the ink film after printing.
According to the resin of the ink system, the hydrogen bonding force and the softening point are dissolved, and the adhesion, flexibility, wear resistance and heat resistance of the printing ink after film formation can be estimated.
According to the parameters of dissolved hydrogen bonding force, it is possible to select appropriate and inexpensive resin and solvent in the process of packaging and printing ink, so as to control the material cost of packaging printing ink.
However, two or more resins or mixed solvents are often used in packaging printing ink products. The calculation method must control its dissolved hydrogen bonding force and surface tension and volatilization rate to accurately obtain the ideal (ie, non-interacting) viscosity of the mixed solution to achieve high quality and low cost ink products - solvent and resin solubility. And the hydrogen bonding force of the ink solution and the substrate (referred to as the dissolved hydrogen bonding force).
Note: The mixed solvent forms a volatile gradient balance due to the combination of speed and slowness, and the volatilization rate is faster than any single solvent component. At the same time, a higher dissolved hydrogen bond force can be obtained during the heating process of the ink film, and the pinhole of the ink film can be prevented. , shrinkage holes and whitish.
On the other hand, under the principle of solvation, the swelling and dissolution of the high polymer are related to the solvation/that is, when the high molecular polymer and the solvent are often contacted, the interaction of the solvent molecules with the polymer molecules This force is greater than the cohesive force between the molecules of the polymer, so that the polymer molecules can be separated from each other and dissolved in the solvent. The attraction of the polar solvent molecules and the polar groups of the polymer can cause solvation to dissolve the polymer. It is well known that this effect is often simply interpreted as: an acidic solvent can dissolve a basic polymer, otherwise it is the opposite. It is often interpreted in theory that an electron acceptor can dissolve an electron donor.
The solvent evaporates from the ink film and is dried, which is called the evaporation rate. Although it has been suggested that the boiling point of the solvent can be used as a basis for predicting its volatility, only this law is met between homologues or petroleum solvents. Therefore, it is still unscientific as a general method, and it is mainly inaccurate. One of the main reasons is the influence of hydrogen bonding. For example, the boiling point of ethanol and benzene is close, while the evaporation rate of benzene is twice that of ethanol. The boiling point of butanol is lower than that of n-butyl acetate, and the volatilization rate is also low. Hydrogen bonding plays an important role in limiting the evaporation of the ink film of solvent-based printing inks.
Of course, temperature, humidity, surface area of the ink film, molecular weight of the polymer, and the magnitude of the surface tension all directly affect the drying speed of the ink film of the packaging printing ink, especially the adhesion fastness after the composite printing (curing).
1. Ink basic theory - "two-dimensional method"
It has been two years since the promotion of the "two-dimensional method", with a focus on Shanghai, Jiangsu, Anhui, Zhejiang, Fujian, Shandong, Shanxi, and Sichuan. At the request of readers at home and abroad, the application of "two-dimensional method" in packaging printing inks is now introduced. Mainly in the system of no heat or endothermic when mixing the non-polar molecules deduced by Helder Brand, and for the system composed of strong polar molecules, because there is hydrogen bond formation, it will exotherm when mixed. The results of this derivation are not applicable to packaging printing inks. To this end, according to the average value (relative value) of the hydrogen bond strength as envisioned by Rebeman, the hydrogen bond force is quantified, and according to the setting, the average value of the weak hydrogen bond is 0, and the average value of the hydrogen bond is 1.0, the average value of the strong hydrogen bond is 1.7, and the formula Q1 and Q2 are the volume fractions of the solvents A and B in the mixed solvent; A and B are the average values of the hydrogen bond forces of the solvents A and B. Later, when we judged from Burrill whether a resin is dissolved in a solvent (or a mixed solvent), we must first confirm the level of the hydrogen bonding force of the resin and the solvent, and then according to the resin and the solvent at the same hydrogen bonding level. Whether the size of the solubility parameter is the same or similar, to determine whether the resin is dissolved in the solvent, the gloss of the ink film after printing, adhesion, etc., so that the molecular polarity and hydrogen bonding force to solubility and printability I have taken it into consideration. Judging from the solubility (including volatilization rate, surface tension, etc.), the correct rate is as much as 95%. Therefore, after more than two years of promotion and application, it has received certain results, and it will not cost manpower and material resources, especially time, as it used to rely on the “stacking” technology.
2, ink design common sense examples
In addition to the basic principles that people usually need, the "two-dimensional ink-making method" mainly bears in mind the solubility of raw materials, hydrogen bonding force, surface tension and evaporation rate. For example:
1PA has a solubility of 10.5, a hydrogen bonding force of 25.92, a surface tension of 460, and a volatilization rate of 2.8.
2 C N is 10.7, hydrogen bonding force is 12.7, surface tension is 420 to 45, and volatilization rate is 3.8.
3PE has a solubility of 7.9 to 8.1, a hydrogen bonding force of 16.10, and a surface tension of 310.
The solubility of 4PP is 7.9 to 8.6, the hydrogen bonding force is 16.16, and the surface tension is 310.
The solubility of 5PET is 10.7, the hydrogen bonding force is 21.89, the surface tension is 400-430, and the volatilization rate is 2.67.
Note: The solubility is generally controlled to be no more than 1 or not less than 1. More importantly, the pH value of each material is mastered and the pH value of the solvent is close. Of course, there is a nitrogen like CN (nitrocellulose). The relationship between quantity and solubility. In general, almost all solvents do not dissolve after a 12.5% nitrogen content.
3. The formation rate of printing ink film and the speed of printing machinery
The dry speed determines the speed of printing. For the convenience of application, it is introduced as follows:
10.7～0.9 30m/min 2 0.9～1.3 50m/min
31.3～1.9 80m/min 4 1.9～2.4 100m/min
52.4～2.8 120m/min 6 2.8～3.3 150m/min
73.3～3.6 180m/min 83.6～4.5 200m/min
In addition, the temperature and humidity of the workshop, the size of the ink, and the viscosity of the ink should be considered here.
4. Examples of general composite ink formulations
Titanium Dioxide 20.0HARDLE-15-LP 7.0 Azetone 17.0Toluene 56.0
Note: 1 dry speed: 2.58 2 Solubility: 8.99 3 hydrogen bonding force: 18.4 4 surface tension: 27.61