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Effect Of Water-based Effect Of Water-based Ink Viscosity On Printing Effect Of Kraft Paper
- May 28, 2018 -

For printing companies, exploring a solution that optimizes aqueous ink formulations with simple processes and low costs has important practical significance. This paper is based on a formula for the printing of water-based inks on the surface of corrugated cartons. Through the adjustment of the viscosity of water-based inks and the kraft paper surface printing effect, the range of water-based ink viscosity that is conducive to improving the surface printing effect of kraft paper printing products is explored to provide printing companies with Certain reference basis.

Experiments

This experiment mainly through the control of water-based ink formulations, the main component ratio of pigments, binders, adding a neutralizer to prepare four different viscosity of water-based red ink. Flexographic printing was used to print on the surface of kraft paper. The tinting strength, gloss and adhesion of the printed pattern were tested to characterize the printing effect of kraft paper.

1 experimental materials

(1) Paper base: One-sided kraft paper with a basis weight of 230g/m2 (Shinhe Paper Products Co., Ltd.) with a tightness of 0.75g/cm3, a bursting resistance of 9kPa・m2/g, and a folding endurance of 60 times. Flexo printing.

(2) Color paste: Red paste (X-Rite ASL010312), color content 45%, light resistance 5 to 6, temperature resistance 180 °C, with good coloring power, stability and fluidity.

(3) Binder: film-forming resin (BASF Joncryl series 8052), non-film-forming resin (BASF Joncryl series 631).

(4) Additives: water-based defoamer 028 (Germany BYK), anti-scratch agent MONENG-1993 (Moton Chemical Co., Ltd.), leveling agent 401LS (Dow Corning), ethylene glycol (Guangzhou Bofeng Technology Co., Ltd.), Neutralizer (urea-modified polyurethane solution).

2 laboratory equipment

High-speed disperser T18 (Germany IKA), 3# Chaen Cup (TQC), reading stopwatch TF307 (Tianfu Huibo Trading Co., Ltd.), density meter i1 (X-Rite), gloss meter WG75 (Shenzhen Welfare Optoelectronics Technology Co., Ltd. Ltd.), pH meter PHS-3C (Shanghai Instrument Science Instruments Co., Ltd.), IGT printability instrument (IGT F1, Netherlands).

3 experimental methods

(1) Preparation of aqueous ink

The main ingredients in water-based inks are pigments, resins and additives. Among them, the pigment provides the ink with the desired color; the resin uniformly disperses the pigment to provide the ink with film-forming properties, water resistance, fluidity, and good printability; the additive has specific functions to improve the performance of the ink itself. Adapt to a variety of different printing conditions. Based on a mature formula developed in the previous period, viscosity is taken as the breakthrough point, and the problem of printing quality brought by many companies' water-based inks is resolved through the perspective of higher scientific content and more cost-effectiveness.

1 Preparation of binders

In this experiment, a self-made linking material suitable for kraft paper printing was used to select film-forming resins with good water resistance, abrasion resistance, film-forming properties and adhesion, and non-film-forming resins with good rheology and printability. According to the proportion of the experimental formula, they were respectively added into a beaker, and then an anti-foaming agent was added and stirred for 15 minutes, and was subjected to standing defoaming. Among them, the film-forming resin accounts for 60% of the binder, the non-film-forming resin accounts for 39.8% of the binder, and the defoamer accounts for 0.2% of the binder.

2 equipped with water-based kraft paper surface printing red ink

First, add the binder, defoamer, and dispersant to the mixing tank according to the recipe. Then, start the dispersing machine and slowly add the red slurry during the stirring. Finally, an antiwear agent, a leveling agent, ethylene glycol, a pH adjuster, and water were added and dispersed at a high speed for 30 minutes.

(2) ink viscosity adjustment

The viscosity of water-based inks is affected by many factors. Neutralizers selected by the formulation reduce the viscosity by hydrogen-enhanced rheological properties, and their rheological properties do not depend on pH and water content. The slight change in the deionized water in the formulation has far less influence on the viscosity than the neutralizer, and therefore can be neglected in the experiment. From Table 1, we can see that adjusting the proportion of neutralizing agent, under the premise of maintaining the consistency of the main components in the ink, is equipped with four water-based kraft paper red inks with different viscosities. The specific viscosity values are as follows: Formula 1 is 19.6±0.5s. Formula 2 was 23.2±0.5 s, Formula 3 was 28.7±0.5 s, and Formula 4 was 31.3±0.5 s.

(3) Printing

Samples of kraft paper were cut into 50 mm wide strips, set at a pressure of 350 N/m2, a squeegee pressure of 150 N/m2, and a speed of 0.6 m/s. Single-ring printing was used to print single-sided red kraft proofs.

(4) performance test

1 Viscosity testing method

According to GB/T 13217.4-2008 "Liquid ink viscosity test standards", measured by the 3 # Zahn cup viscometer method. According to the regulations, the temperature of the ink to be tested is controlled at 25° C., and the ink temperature is adjusted in the test process; the cleaned and air-dried Zahn cup is supported horizontally, and the bottom hole is blocked with a finger and poured into the sample. Water-based ink, the ink height is flush with the upper edge of the Zahn cup; the height of the Zahn cup cannot be higher than 15 cm above the liquid surface, release the finger and actuate the stopwatch at the same time, and when the first droplet of the sample is interrupted, the first drop will appear. The timing and stopwatch display time is the viscosity of the ink.

2 tinting strength measurement

Weigh 1g of standard red ink and 10g of white ink in the balance, and use the same method to weigh the same proportion of homemade red ink and white ink, and mix thoroughly with the ink-adjusting knife; then, mix the ink and dilute, and take the sample and put it in the sample On the upper left side of the paper, the ink sample was scraped on the upper right; the scraper was used to scrape 80mm to 100mm long from the top. Observe the ink color of the sample on the sample. Change the sample by adding white ink until the sample is flushed with the sample. Use the following formula to obtain the sample.

Color force.

S=D/C×100%

Among them, S is the percentage of coloring power (%), D is the amount of white ink used to dilute the sample (g), C is the amount of white ink used to dilute the standard (g).

3 gloss measurement

According to GB/T 8941-2013 “Determination of Specular Gloss of Paper and Cardboard”, this experiment adopts WG75 gloss meter to measure. After the kraft paper was printed, the surface gloss was measured using a 75[deg.] angle.

4 Adhesion measurement

According to the requirements of GB/T 9286-1998 “Skew test of paint and varnish paint film”, first use a blade to draw out a 5×5 1mm2 small grid on the water-based red ink-printed kraft paper, and then stick it with 3M tape. Draw a small grid test area, and then use your fingers to grasp the tape and quickly pull it down along the printed surface. According to the condition of ink shedding, it is graded according to the grade.


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