Antibacterial UV inks provide protection for green security printing

With the continuous improvement of people's living standards, consumers have higher and higher requirements for the health of commodity packaging. Our company actively innovates in the principle of protecting consumers' health and satisfying consumers' needs, and has developed an antibacterial UV drying ink ( Antibacterial UV ink), and was first used in folding carton printing, giving the folding cartons strong antibacterial properties, effectively cutting off the spread of pathogens on folding cartons, and protecting consumers' health. Moreover, our company applied for a national invention patent “An antibacterial UV drying ink and its preparation method” (Patent No.: ZL201210422539.7) for this technology, and obtained the authorization. In this article, the author will discuss the ink preparation process, printability and antibacterial performance in order to provide useful reference for the industry peers.

Preparation Process

1. Main material

Potassium sorbate (purity >98%); sodium diacetate resin (purity >98%); pigment: benzidine yellow; UV linking agent: epoxy acrylate, urethane acrylate; photoinitiator: benzoin dimethyl ether; dilution Agent: trimethylolpropane triacrylate.

2. The main equipment

JFA- II automatic film coating machine, electric constant temperature incubator (DH2500AB), Ruizhi purification table (VD-650), rotary rheometer (NEW DV3T), pH meter (PHS-3C), coated glass cup viscometer , ATP Fluorescent Bacterial Detector (BLW-0401), Electronic Analytical Balance (JF2004), Glossmeter (JFL-B45°), Three Roller Mill (S65).

3. Preparation steps

(1) Potassium sorbate and sodium diacetate were compounded in a ratio of 7:3, deionized water was added, and the mixture was mixed and stirred.

(2) The UV linking material is put into the reactor for heating. When the temperature reaches 120-130° C., the heating is stopped. When the temperature drops to 110° C., the photoinitiator is thrown into the reaction vessel and stirred uniformly.

(3) When the temperature is lowered to 100°C, pigments and thinners are added in order.

(4) continue to cool to 60 °C, adding step (1) prepared by the preparation of the antibacterial agent and stabilizer, wax, leveling agent, defoamer, stir evenly after rolling with a three-roll mill, evenly dispersed That is, an antibacterial UV ink having a fineness of 15 to 25 μm is obtained.

Printability and Antibacterial Performance Analysis

The printability of the ink has an important influence on the printing process and print quality, and the ink must match the printing requirements. Next, the antibacterial UV ink was tested on the “Double Happiness (Sunshine Good Times)” hard case undertaken by our company, and the viscosity, drying performance, and two common food contaminating bacteria E. coli that affect the printability of the antibacterial UV ink were examined. The antibacterial properties of Staphylococcus aureus were tested and analyzed.

1. Viscosity

In the printing process, the viscosity of antibacterial UV inks is very demanding. If the viscosity is too high, the transfer performance of the ink may be deteriorated, and the quality problems such as a dirty plate and a pasting plate may be easily caused. If the viscosity is too low, the printing color may be lighter, the dots may be expanded, and the ink may not be uniform. According to GB/T 13217.4 "viscosity test method of liquid ink", the general viscosity should be controlled at 25 ~ 35s.

At room temperature 25°C, the viscosity of the antibacterial UV ink prepared with different proportions of antibacterial UV ink and thinner was tested using a No. 4 cup. The viscosity of each set of antibacterial UV ink was averaged after 3 tests.

When the specific gravity of the diluent increases, the viscosity of the antibacterial UV ink decreases significantly. This is due to the dilution of the epoxy acrylate and urethane acrylate after the addition of the diluent, which causes the entire system to expand and the viscosity to drop rapidly, but the viscosity remains at 25.1 - Within the range of 35.4s, it conforms to the usage standard of gravure UV ink.

2. Drying performance

Due to the high printing speed of the gravure printing machine, the thickness of the gravure ink layer is generally 10 to 20 μm, and some even reach 40 μm. If the ink layer has poor drying properties, the graffiti may easily occur, and the gloss of the ink layer may deteriorate. Insufficient tensile strength, as well as common quality problems such as over-displacement, and the need for antibacterial UV ink to meet the needs of fast printing speed, ink drying speed can also meet the printing performance requirements.

To this end, we tested the drying performance of antibacterial UV inks at 25°C room temperature. The results showed that the initial dryness of antibacterial UV inks was 20 μm and the dry time was 45 s. It had fast drying and good gloss after film formation. The characteristics of the ink layer effectively overcome the problems of thick gravure ink layer and slow drying. It is more suitable for gravure printing production.

3. Antibacterial properties

The antibacterial property is to evaluate whether the antibacterial UV ink printed product has bactericidal and antibacterial properties. According to GB/T21510-2008 "Test methods for antibacterial properties of nano-inorganic materials", the prepared antibacterial UV ink was placed for one month and printed on a "Double Happiness (sunny day)" hard box to obtain a sample, with the use of ordinary UV ink The printed samples were compared for appearance without significant hue changes, as shown in FIGS. 1 and 2 . At the same time, the antibacterial effect of two common food-contaminating bacteria, Escherichia coli and Staphylococcus aureus, was tested. The antibacterial rate of each group of antibacterial UV inks was averaged after 3 tests.

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