For a long time, the "technical stacking method" added and subtracted in the packaging printing ink manufacturing and packaging printing process and the "intrinsic viscosity method" commonly 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 maximum intrinsic viscosity system obtained 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 Put the cross-linked polymer in a solvent with different solubility parameters for swelling. When the equilibrium is reached, determine the swelling degree and the system with the largest swelling degree. The corresponding solubility parameter of the solvent system is the polymer. Solubility parameters), these two are currently used to determine the solubility of polymer compounds is relatively simple and intuitive method, far from being able to meet the requirements of modern packaging and printing technology. ?
The "two-dimensional ink making method" described in this article is based on the principle that the solubility parameters are the same or close to each other, to determine whether the resin is dissolved in the solvent or mixed solvent and the miscibility 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 of mutual solubility of the same or similar solubility parameter values. ?
The third is based on the solubility parameter, you can estimate the miscibility of two or more resins (the upper and lower parameters can not be greater than 1.5) 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. The range of solubility parameters of the resin and the substrate can be determined through experiments. ?
Fifth, according to the solubility parameter, we can judge the solvent resistance of the ink film after printing. ?
Sixth, according to the resin of the ink system, dissolving the hydrogen bonding force and softening point, the adhesion, flexibility, wear resistance and heat resistance of the printing ink film can be estimated. ?
Seventh, based on the dissolved hydrogen bonding force parameters, suitable and inexpensive resins and solvents can be selected in the process of developing packaging printing inks in order to control the material cost of packaging printing inks. ?
However, two or more resins or mixed solvents are often used in packaging printing ink products. Its calculation method must control its dissolved hydrogen bonding force, surface tension and volatilization rate to accurately obtain the ideal (that is, non-interacting) viscosity of the mixed solution, so as to achieve the solubility of high quality and cheap ink products-that is, solvent and resin Hydrogen bonding force with ink solution and substrate (referred to as dissolved hydrogen bonding force). ?
Note: The mixed solvent forms a volatile gradient balance due to the combination of speed and speed. The rate of volatilization is faster than that of any single solvent component. At the same time, a higher hydrogen bonding force can be obtained during the heating of the ink film, and pinholes in the ink film can be prevented. , Shrinkage and whitening. ?
On the other hand, under the principle of solvation, the swelling and dissolution of its high polymer are related to the solvation / that is, when the polymer and the solvent are in contact, the interaction force of the solvent molecule on the polymer molecule This force is greater than the cohesive force between the polymer molecules, so the polymer molecules can be separated from each other and dissolved in the solvent. Polar solvent molecules and polymer polar groups attract each other to produce solvation, so that the polymer dissolves. Everyone knows that this effect is often simply explained as: acidic solvents can dissolve alkaline polymers, otherwise the opposite is true. It is often explained in theory that the electron acceptor can dissolve the electron donor. ?
The solvent volatilizes and dries from the ink film, which is called the volatilization rate. Although it has been suggested that the boiling point of the solvent can be used as a basis for predicting its volatility, only the homologues or petroleum solvents comply with this rule. Therefore, it is no longer scientific as a general method, mainly because it is inaccurate. One of the main reasons is the influence of hydrogen bonding. For example, the boiling points of ethanol and benzene are close, and the volatilization 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, ink film surface area, molecular weight of polymer, surface tension, etc. all directly affect the drying speed of packaging printing ink film, especially the adhesion fastness after lining and printing (curing). ?
1. Basic theory of ink-"two-dimensional method"?
It has been two years since the promotion of the "two-dimensional method", and its scope has focused 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. It is mainly a system that absorbs non-polar molecules derived from Herder Brand without heat or endotherm when mixing, and for a system composed of strongly polar molecules, because of the formation of hydrogen bonds, it will exotherm when mixed, then The derivation results are not applicable to packaging printing inks. For this reason, according to the average value (relative value) of the hydrogen bond strength assumed by Leiberman to quantify the hydrogen bonding force, and according to its setting, the average value of the weak hydrogen bond is 0, and the average value of the middle hydrogen bond is 1.0, the average value of the strong hydrogen bond is 1.7, the calculation formulas Q1, Q2 are the volume fractions of the solvents A and B in the mixed solvent; A, B are the average value of the hydrogen bonding force of the solvents A and B. Later, when we judge whether a resin is dissolved in a solvent (or mixed solvent) from Burrill, we must first confirm the level of the hydrogen bonding force between the resin and the solvent, and then based on the resin and solvent at the same hydrogen bonding level The principle of whether the internal solubility parameters are the same or similar is to determine whether the resin is dissolved in the solvent, the gloss of the ink film after printing, adhesion, etc., so that the polarity and hydrogen bonding force of the molecule will affect the solubility and printability. Wait for it to be taken into account. Judging from the solubility alone (including volatilization rate, surface tension, etc.), the accuracy rate reached as much as 95%. Therefore, after more than two years of promotion and application, it has achieved certain results. It does not mean that it will consume manpower and material resources, especially time, by adding and subtracting "stacking" technical methods as before. ?
2. Examples of common sense of ink design?
In addition to the basic principles that people usually need, the "two-dimensional ink making method" mainly keeps in mind the solubility of raw materials, hydrogen bonding force, surface tension and volatilization rate. E.g:?
â‘ The solubility of PA is 10.5, the hydrogen bonding force is 25.92, the surface tension is 460, and the volatilization rate is 2.8. ?
② CN is 10.7, hydrogen bonding force is 12.7, surface tension is 420 ～ 45, and volatilization rate is 3.8. ?
③The solubility of PE is 7.9 ～ 8.1, the hydrogen bonding force is 16.10, and the surface tension is 310. ?
④The solubility of PP is 7.9 ～ 8.6, the hydrogen bonding force is 16.16, and the surface tension is 310. ?
⑤The solubility of PET 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 no less than 1. More importantly, the pH value of various materials is close to the pH value of the solvent. Of course, like CN (nitrocellulose) there is also a nitrogen The relationship between the amount and solubility. Generally speaking, after the nitrogen content exceeds 12.5%, almost all solvents cannot be dissolved. ?
3. The formation rate of printing ink film and printing machine speed?
The drying speed determines the speed of the printing speed. In order to facilitate the application, the introduction is as follows:
①0.7 ～ 0.9 30m / min ②0.9 ～ 1.3 50m / min
③1.3 ～ 1.9 80m / min? ④1.9 ～ 2.4 100m / min
⑤2.4 ～ 2.8 1200m / min ⑥2.8 ～ 3.3150m / min?
⑦3.3 ～ 3.6 180m / min ⑧3.6 ～ 4.5 200m / min?
In addition, the temperature, humidity and size of the workshop, as well as the viscosity of the ink, should be considered here. ?
4. Examples of general compound ink formulations?
Titanium dioxide 20.0? HARDLE-15-LP 7.0? Butanone 17.0? Toluene 56.0?
Note: â‘ Drying speed: 2.58? â‘¡ Solubility: 8.99? â‘¢ Hydrogen bonding force: 18.4? â‘£ Surface tension: 27.61
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