Preparation of Plastic Gravure Water Based Ink Based on Composite Emulsion

[Abstract] A polyurethane-polyacrylate composite emulsion was prepared by emulsion copolymerization and a plastic gravure aqueous ink was prepared using phthalocyanine blue as a pigment. The blocking agent acrylic acid-p-hydroxyethyl ester content and pigment content of aqueous ink were discussed. The impact of performance. The results showed that the viscosity of PUA composite emulsion and water-based ink increased with the increase of HEA content, but the stability of the ink first improved and then decreased; with the increase of pigment content, the stability of aqueous ink became worse, 13% of the pigment The content is suitable; the water-based ink not only has excellent fastness to the PET film, but also has good fastness to the OPP film and has good water resistance.

Keywords: polyurethane; polyacrylate; emulsion; plastic gravure water-based ink

In recent years, water-based inks have attracted increasing attention due to their characteristics of being free of volatile organic solvents, non-flammable, non-toxic and odor-free. As the ink "heart" of the connection material determines the performance of the ink, especially printing performance, such as viscosity, dryness, fluidity, gloss and so on. The binder in the aqueous ink consists mainly of an aqueous resin solution and an emulsion polymer. The former is suitable for wetting and dispersing pigments, while the latter provides critical application properties for aqueous inks. At present, aqueous acrylic resins and acrylic emulsions are more commonly used. Waterborne polyurethane, as a new type of environmentally friendly material, has excellent adhesive properties, abrasion resistance, scratch resistance and good low temperature properties, high gloss and gloss retention, and has broad application prospects in the field of aqueous inks. A single aqueous polyurethane has the disadvantages of poor solvent resistance and water resistance, and lacks adhesion to non-polar films OPP. Polyurethane-polyacrylate (PUA) combines the advantages of polyurethane and polyacrylate, and has a certain application value as a binder for water-based inks. In this paper, a polyurethane-polyacrylate composite emulsion was synthesized by emulsion copolymerization, and its application in plastic gravure aqueous inks was discussed.

1 experiment

1.1 Raw materials

Polyester polyol (108 type), relative molecular weight 2000, Jintan adhesives factory; toluene diisocyanate (TDI-80), industrial products, Germany BASF; dimethylol propionic acid (DMPA), chemical pure, Taixing Chemical Factory; methyl methacrylate (MMA), chemically pure, Shanghai Lingfeng Chemical Reagent Co., Ltd.; acrylic acid-p-hydroxyethyl ester (HEA), chemical pure, Shanghai Lingfeng Chemical Reagent Co., Ltd.; triethylamine (TEA), Analytical Pure, Shanghai Tingxin Chemical Reagent Factory; Potassium Persulfate, Chemical Pure, Shanghai Lingfeng Chemical Reagent Co., Ltd.; Sodium Bicarbonate, Analytically Pure, Shanghai Hongguang Chemical Factory; Blue Silica Gel, Nanjing Cable Special Packing Products Co., Ltd.

1.2 PUA emulsion preparation

Preparation process of PU emulsion: A certain amount of dehydrated polyester was added together with TDI\DMPA to a four-necked flask equipped with a thermometer, stirrer and reflux) and reacted at 80°C for 1.5 hours.) At 56°C, an appropriate amount of catalyst and acetone was added dropwise, and the reaction was continued for 3 hours; then, based on the remaining -NCO, a certain amount of HEA was added. After 3 hours of reaction, the metered triethylamine was neutralized and neutralized with vigorous stirring. Next, the system was emulsified by adding deionized water, and then a portion of the acetone was distilled off to obtain the desired HEA-capped PU emulsion.

PUA emulsion preparation process: In a four-necked flask, add the prepared PU emulsion, emulsifier, and emulsify rapidly for 0.5 h. The initiator potassium persulfate and MMA were added dropwise at 80°C. The PUA emulsion was obtained after 2h of instillation for 1 h. In this experiment, PU/MMA = 60/40 (mass ratio), PU type: the molar ratio of HEA to the remaining -NCO (r) is 0.2, 0.3, 0.4, 0.5 respectively. PU emulsion. The corresponding PUA emulsions prepared were designated PUAl, PUA2, PUA3, PUA4, respectively.

1.3 Preparation of Water-based Ink

The PUA emulsion synthesized above is mixed with pre-ground blue phthalocyanine pulp and other additives, and mechanically blended to obtain a water-based ink.

1.4 Analysis and Testing

1) Infrared analysis. Infrared Analyzer Nexus 670FT-IR, Nicolet, USA, 16 scans, spectral resolution 2cm-1, test sample film

2) Emulsion Viscosity Test According to GB/T 1723-1993, the relative viscosity of the emulsion was measured with a coating-4 viscometer.

3) Determination of water absorption. Weigh the mass of W1 latex film, immersed in deionized water, remove the surface water after 24h with filter paper, weighed as W2, the water absorption rate can be calculated by the following formula: Water absorption (%) = [(W2-W1) / W1]x100%.

4) Ink stability test. Accelerated settling tests can generally be performed by centrifuges to simulate storage stability. The sample was placed on a 80-2 centrifuge in the Shanghai Surgical Instrument Factory and centrifuged for 15 minutes at a rate of 3000r/min. If there is no precipitation, it can be considered that there is a stable period of 6 months of beryllium deposit.

5) Ink viscosity test. The viscosity of the aqueous ink was measured at 30 r/min, 25°C using a rotary viscometer NJD-1 ROTA- TIONALVISCOMETER, rotor number 1.

6) Attachment fastness test. The aqueous ink was applied onto the OPP and PET films using a silk bar, dried completely at 80° C., and tape was applied to the printed film. After being uniformly kneaded, the film was rapidly peeled off and the surface state of the printed film after peeling was examined. Visual inspection standards are good; giant mouth brush film residue is more than 90%; Qualified: 60-90% of printed film remains; poor: less than 60% of printed film residue.

7) Water-based ink water resistance test. The sample ink obtained above was subjected to a scraping test. The sample was as uniform as possible without leaving a portion of the thick ink layer, and was dried at room temperature. Will be cut by the ink scraping width of about 1.5cm, about 10cm long strips, into a test tube with water soaked (test tube should be filled with half the length of the test tube of water), and make the ink scraping Half soaked in water. After soaking for 24 hours, remove the ink with a tweezers, wipe the sample with distilled water: wash it to neutrality, and dry it at room temperature. Check the degree of change of the ink scraping (that is, the difference between the soaked and unsoaked portions) and the solution. The degree of dyeing is graded according to the regulations listed in Table 1 according to the degree of change of the ink scraping and the degree of staining of the solution.

(to be continued)