Organic solvent problem

Abstract : The degree of accommodation of organic solvents can be used to represent the suitability and miscibility of polyamide resin and nitrocellulose (nitrocellulose) systems for various common organic solvents in plastic intaglio printing inks; Amide resin and nitrocellulose system dissolution quality. For the analysis of the solvent acceptance of this polyamide resin and nitrocellulose system, more readers can understand it and apply it. In this paper, a simple test description is given for the solvent-acceptance of the polyamide resin and nitrocellulose system. It can also be said that the wise sees the wisdom and the person sees the energy and goes to the false preservation. I believe there is a need for each. Take it.

Keywords: polyamide resin, nitrocellulose (nitrocellulose), degree of containment, titration analysis, test methods.

The foregoing

Polyamide resin and nitrocellulose (nitrocellulose) are one of the most widely used constituents of the main film-forming resin in plastic intaglio printing inks. General requirements for the use of non-reactive polyamide resins and low-second-count nitrocellulose in plastic intaglio printing inks, due to its main film-forming component has good adhesion to many plastic films, good drying, organic solvent release Faster; however, the solubility of this type of non-reactive polyamide resin and low-second-count nitrocellulose components in some different organic solvents is quite different. At present, most non-reactive polyamide resins or nitrocellulose resins produced in China or even abroad are not very satisfactory in the solubility of a single organic solvent. Ink manufacturers use this type of polyamide resin or Nitrocellulose resins are generally dissolved using a mixed organic solvent. Therefore, as an ink manufacturer applying such a polyamide resin and a nitrocellulose composition system, it is necessary to make some comprehensive comparisons between the degree of accommodation of this type of polyamide resin and the nitrocellulose composition system with respect to some common organic solvents. Test analysis, in order to apply these polyamide resins and nitrocellulose resins to create inks have a reference value. This article is based on a certain brand of solid polyamide resin made in China and a certain type of low-second-count nitrocellulose resin. The analysis of the solvent accommodating degree is carried out for the reference of the people who use this type of resin. In addition, it was suggested that it could be used in an analogy to refer to other scientific aspects of applied materials.

principle

For the problem of the degree of acceptability of the organic solvent of the polyamide resin and the nitrocellulose system, we have not made this index requirement when testing the raw materials of the polyamide resin and the nitrocellulose, but we can analyze from the perspective of the ink manufacturing process. According to the scientific theory and practical experience, the compatibility of a mixture of polyamide resin and nitrocellulose used in plastic intaglio printing inks for various common organic solvents is directly related to the viscosity and fluidity of such inks. Many important ink performance indicators such as gloss and printability; it is also a complex ink that controls the quality of such ink products and evaluates polyamide resins, nitrocellulose, auxiliary resins, different organic solvents, pigments, waxes, additives, etc. The important parameters of the system. The "accommodation degree" is a method that can numerically indicate the compatibility of the polyamide resin and the nitrocellulose system with respect to the organic solvent.

As engineers and technicians of ink manufacturing know, the process of dissolving high molecular compounds such as polyamide resin and nitrocellulose in organic solvents is a process in which small molecules of solvent are sufficiently diffused into macromolecule compounds such as polyamide resin and nitrocellulose. In the process, the macromolecular chain of the macromolecular compound is well spread in the solvent. The solution of a polymer compound such as a polyamide resin and nitrocellulose in a well-dissolved state is often homogeneously dispersed, clear and transparent. At a certain system temperature, the dissolution properties are often related to the respective properties of the polyamide resin, nitrocellulose, and organic solvents. For a system in which a polyamide resin and a nitrocellulose are mixed in a plastic intaglio printing ink, , we set the 40% polyamide resin solution concentration and 25% nitrocellulose solution concentration at a temperature of 25°C and mixed with 7:3, and under normal conditions exhibit a good dissolution state, the mixture is homogeneously dispersed Clear and transparent. However, our analysis shows that when the polyamide resin and the nitrocellulose dissolving system are continuously added to the dissolving system with an organic solvent, the molecular chains of the polyamide resin and the nitrocellulose are gradually improved When the stretched state is turned to a tight state, the solvent molecules embedded in the macromolecules of the polyamide resin and the nitrocellulose will gradually be squeezed out. This process is a process in which the resin polymer is continuously shrinking and the solvent molecules are constantly being squeezed out. To a certain degree, the homogenous state of the mixture of the polyamide resin and the nitrocellulose will be destroyed, and the solution (resin liquid) will change from clear and transparent to turbid and opaque, while the polyamide resin and the nitrocellulose Also began to precipitate from the solution to form a precipitate. The “inflection point” of transition from clear and transparent to turbidity is to judge the cloud point of the solvent capacity of the polyamide resin and nitrocellulose. The ratio of the solvent weight used in the titration solution system to the weight of the solution system is the solution. The degree of containment of the system relative to a certain solvent is expressed in g/100g units.

Experimental procedure

The method of analyzing the solvent-receiving degree of the polyamide resin and the nitrocellulose resin is mainly to titrate the resin solution with various organic solvents until the resin solution turns from a uniform to a cloudy and opaque one. The “accommodation value” is used to express the unit of g/100g. Since the polyamide resin used for printing ink is classified into benzene-soluble and alcohol-soluble, their degree of acceptability for various organic solvents is quite different, and even varies greatly. Therefore, the preparation methods of the two mixed systems of polyamide resin and nitrocellulose are introduced separately.

First, the test solution was prepared by weighing a certain amount of solid polyamide resin and slightly alcohol-wet low-second-count nitrocellulose resin, and dissolving it into 40% polyamide resin solution and 25% nitric acid according to the proportion of organic solvents. Cellulose solution was then mixed 7:3 into a uniform transparent polyamide resin and nitrocellulose system solution.
1) Benzene-soluble 40% polyamide resin solution:
Benzene-soluble polyamide resin 40%
Benzene organic solvent 30%
Alcohol organic solvents 15%
Ester organic solvents 15%
Benzene soluble 40% polyamide resin solution 100%

2) Benzene-soluble 25% nitrocellulose solution:
Low-second nitrocellulose 25%
Benzene organic solvent 25%
Alcohol organic solvent 20%
Ester organic solvents 30%
Benzene soluble 25% nitrocellulose solution 100%

3) Alcohol-soluble 40% polyamide resin solution:
Alcohol-soluble polyamide resin 40%
Alcohol organic solvent 40%
Ester organic solvents 20%
Alcohol soluble 40% polyamide resin solution 100%

4) Alcohol-soluble 25% nitrocellulose solution:
Low-second nitrocellulose 25%
Alcohol organic solvents 30%
Ester organic solvents 45%
Alcohol soluble 25% nitrocellulose solution 100%

Second, the titration analysis

Separately weigh 100 g or more of the uniform (7:3) mixed polyamide resin and nitrocellulose solution mixed in a transparent glass beaker and titrate to a mixture with various organic solvents. The solution of the system was changed from clear and transparent to turbid, and the weight of the organic solvent used for each titration was recorded in grams, and the number of columns was tabulated for comparative analysis.

Third, watchmaking comparison

T=25°C, N=60-70%, Viscosity measured with Zahn 3# cup mixture Solvent Benzene-soluble polyamide resin and nitrocellulose system solution Alcohol-soluble polyamide resin and nitrocellulose solution Solvent max. Degree G/100G Viscosity S/25°C Solvent Maximum Acceptance G/100G Viscosity S/25°C
Ethanol 100.44 9 146.25 19
Isopropanol 175.20 10 225.50 17
Butanol 463.15 7 562.35 15
Ethyl Acetate 15.36 28 89.52 26
Butyl acetate 9.58 30 70.46 27
Toluene 109.95 13 246.20 18
Xylene 66.65 24 198.75 20
Butanone 6.61 29 15.68 35
Ether 23.56 27 40.32 33
Dibutyl ether 16.03 28 32.20 34

Table 1: Degree of Acceptance of Polyamide Resin and Nitrocellulose System Solution for Various Single Organic Solvents According to the expressions of the degrees of acceptability of several common single organic solvents for polyamide resin and nitrocellulose system solutions above, We can know that for a benzene-soluble solution system, the acceptability of a single organic solvent is far less than that of an alcohol-soluble solution system. The greater the resin's ability to accept the solvent, the worse the solvent release of the resin is. The slower the thoroughness; the conclusion of this analysis coincides with the fact that the phenol-soluble resin we know is more dry than the alcohol-soluble resin.

Since gravure inks formulated with our polyamide resins and nitrocellulose systems are generally diluted with more than two organic solvents, it is also necessary to titrate polyamide resins with nitrocellulose with organic solvents. The solution of the prime system is tested to determine the degree of its acceptance of the organic solvent mixture. According to the following ratio, several organic solvents are mixed together, and the solvent acceptance of the polyamide resin and nitrocellulose system solutions is analyzed:

E01 mixed solvent (toluene: isopropanol = 7:3)
E02 mixed solvent (toluene:isopropanol:ethyl acetate=5:3:2)
E03 Mixed Solvent (Toluene: Isopropanol: Butyl Acetate: Butanone = 4:3:2:1)
E04 mixed solvent (toluene: isopropanol: butyl acetate: butanone:ether=3:3:2:1:1)
T=25°C, N=60-70%, Viscosity measured with Zahn 3# cup mixture mixed solvent Benzene-soluble polyamide resin and nitrocellulose system solution Alcohol-soluble polyamide resin and nitrocellulose solution Solvent maximum Acceptance G/100G Viscosity S/25°C Solvent Maximum Acceptance G/100G Viscosity S/25°C
E01 450