In China, most of the water-based inks used are melamine rosin, which accounts for about 70% of the total amount. Such resins have the advantages of low price, simple manufacturing process, and high ink gloss. The disadvantage is that the ink produced has poor water resistance after printing. , The printing process is not stable. It can only be used to print general carton boxes. It can not meet the requirements of gloss and water resistance required for medium and high-grade packaging printing.
Chen Xueheng and other natural rosin as raw materials, modified by fumaric acid, pentaerythritol, synthesis of low cost, high softening temperature, a variety of good solubility and excellent overall performance of fumaric acid modified pine resin.
Feng Lianxiang used acrylic acid to modify rosin to obtain a water-soluble modified rosin tackifier, which was then copolymerized with polyvinyl butyral (PVB) to obtain excellent adhesion and water solubility. Water-soluble ink binder for paper.
2.2 modified acrylic resin
Now high-end inks are basically water-soluble acrylic modified resin for water-based inks. Water-based acrylic resins have undergone several years of research, and there has been great progress in terms of modification. They are composed of sulfonated polyester resins and water-soluble acrylic resins. The unique system can significantly eliminate the odor of water-based ink due to the presence of ammonia water; with 50% polyacrylic resin, not only can the same plasticizing effect be achieved, but the performance of the ink will not be impaired, and no molecular migration will occur after printing. The ink has better environmental protection performance; water-based inks and varnish made from water-based acrylic resin materials can increase the gloss of printing by 20% to 30% while maintaining the drying speed, transparency, color density, heat resistance, kneading resistance and scratch resistance. Rubbing resistance, water resistance, grease resistance, acid resistance, etc., but abrasion resistance is slightly reduced; adding a special water-dispersible long oil-based alkyd resin to the acrylic emulsion to make the ink with good Fast drying and adhesion, low VOC, good acid and alkali resistance, can be used to make gravure and flexo printing inks, varnish and primer for composite paper; Acrylic resin is mainly used in the manufacture of "wet" packaging printing inks, such as fruit and vegetable packaging printing, has good friction resistance, resistance to dry rubbing, and the ink film is not anti-adhesion.
The introduction of styrene in acrylic acid improves the alkali resistance, antifouling property, anti-powdering property, high gloss and hardness of the film forming material, making the formulated aqueous ink good printability, wet rub resistance, and high gloss. Good adhesion, suitable for gravure printing, can be used for different types of paper and plastic film.
Chen Xi and others used the ketone aldehyde prepolymer and acrylate copolymer to obtain a water-based resin with good gloss, good adhesiveness, excellent film-forming properties, and good water resistance and weather resistance after film formation. The advantages and good advantages of waterborne acrylate polymer weather resistance, transparency and film forming properties, and good water solubility have resulted in a good gloss, good adhesion, good film forming properties of the ketone aldehyde modified acrylic Resin.
2.3 emulsion type material
In recent years, emulsion-based linking materials have developed rapidly, especially the development of composite emulsions.
Cai Dongyu [combined the advantages of waterborne polyurethane and the advantages of acrylic resin, using polyurethane 2 polyacrylate (PUA) composite emulsion prepared by emulsion polymerization method, obtained good water resistance, excellent adhesion to PET film and OPP film Water-based ink binders such as fastness, good stability and the like, and the resulting aqueous inks are used in plastic gravure printing.
Hu Lehui applied the step polymerization method of seed polymerization to synthesize a three-layer emulsion of core/middle/shell with methyl methacrylate, methacrylic acid, ethyl acrylate, and polyalkenyl unsaturated monomers. Ink printing can get colorful, full, good hiding power printing effect.
Cui Jinfeng uses acrylic acid and its esters, methacrylic acid and its esters, and other olefin monomers to obtain an acrylic copolymer emulsion by free-radical polymerization, and then it is combined with a modified rosin resin solution to form a composite resin. Thinning layering and thickening phenomenon, and good printability, "body" good, dry fast, high gloss, printing film wear and water resistance.
Nowadays, in order to meet the requirements of more printing sites, water-based inks continue to produce new technologies, which have greatly improved the performance of inks, such as a stable pH system, high gloss, water resistance, and heat resistance. , printability of extreme environments, etc. The improvement of performance is mainly focused on the improvement of the linking materials. Improvements in the composition and preparation of water-based binders, such as the introduction of nanotechnology, and the use of different resins, have improved the performance of aqueous inks to some extent.
3 Application of water-based binders
As a key material for water-based inks, binders play a decisive role in the performance of inks. When selecting the binder resin, it is necessary to consider the practicality, performance, and market price of the resin, thereby improving the ink performance, reducing the price of the aqueous ink, and obtaining more markets.
In Europe and the United States, the market share of water-based inks has reached 95%. The current annual output of water-based ink in our country is about 100,000 tons, and this figure will also increase substantially in the future. At present, the characteristics of China's ink-ink market are: the existing ink-and-ink production plants mainly produce low-grade ink (used for paper bag printing, packaging carton printing, envelope printing, etc.); cigarette bags, wine labels, food packaging, etc. that use mid-range ink and water, and imports. Domestic ink and wash inks each account for half; high-end inks used in plastic packaging, decorating and printing, lottery cheques, etc. are mainly imported. Studies on the water-based resins used today show that the relationship between the viscosity and content and pH of most water-reducible resins is non-linear. In the printing process, the ink constantly changes in viscosity as water and ammonia evaporate. If the mutation is undoubtedly very unfavorable for printing, adding a cosolvent to the ink can solve this problem.
However, most acrylic emulsions are susceptible to demulsification in cosolvents and the stability of the ink during storage cannot be guaranteed. The printing of many film materials, due to the limitations of printing conditions, must add a lot of solvents to the ink to adjust the drying speed, so the current water-based ink is difficult to achieve a breakthrough in film printing.
Both high-grade water-based inks and low-grade water-based inks have problems such as unstable system pH, poor re-solubility, limited application in alkaline conditions, freezing environments, and high-magnetic environments, etc., and also require ink performance. Improve to suit more printing occasions.
4 Outlook
The main issues facing the development of water-based inks are the suitability of resins, the development of basic binders and high-performance resin systems. Synthesize two or more resins, synthesize the advantages of each binder, obtain better ink performance, and develop resins with excellent performance using interpenetrating emulsion network technology and core-shell composite emulsion technology. This is a water-based binder. The direction of future development.
At present, as an environmentally friendly water-based ink, the improved properties of its water-based binders are:
(1) Developed an aqueous binder that stabilizes the pH of ink, that is, no need to detect and adjust the pH during printing.
(2) Improve the performance of the resin to make it easier to dissolve. Under the premise of ensuring print drying and film forming, further improve the re-solubility of the water-based ink to ensure that the printing system can run for a longer time before cleaning. Reduce or even eliminate print defects such as stencils.
(3) The resin is more water-based, and more resins are used to make water-based resins to obtain water-based binders, continue to improve the performance on weakly absorbent or non-absorbent substrates, and make the resulting resin There is a big breakthrough in resistance to alkali, oil, grease and better heat and freeze resistance.
(4) In the modification of the resin structure, the ink can be applied to high magnetic properties and does not decolorize in water for a longer period of time, and the limitation of breaking the printing occasion makes the aqueous ink widely applicable to high-grade printing such as film.
(5) Further reduce the content of volatile organic compounds and adapt to the increasing trend of environmental protection requirements.
With the rapid development of modern polymer materials science theory and modern biotechnology and materials synthesis technology, we can start with the relationship between polymer structure and properties, use new polymerization method technology to modify the resin structure and composite with other materials. Get a comprehensive performance of the water-based ink binder.