Joanna Izdebska

Hyperbranched polymers – their application in printing inks

Urania® flexographic printing ink was modified with the commercially available hyperbranched polymer Boltorn H2004. The surface tension of the printing inks was measured and the rheology behaviour of the printing inks was assessed. The flow curves (shear stress vs. shear rate) for the printing inks exhibited pseudoplastic behaviour. Modified flexographic inks were laboratory printed on three different plastic films: polyethylene, polypropylene and polyethylene terephthalate. The impact of a small amount of hyperbranched polymer on printing ink colour was examined by optical density, total colour difference ΔE ∗ (CIE L ∗, a ∗, b ∗) and the gloss of the printed film. In general, the addition of the hyperbranched polymer improved the colour fastness and hardness resistance. The influence of the hyperbranched polymer on the rheological properties, optical density, CIE LAB coordinates and colour fastness is discussed.

1 – Printing on Polymers: Theory and Practice

In this chapter, a short history of printing and its meaning are given. All printing techniques used for polymer printing as well as some decorative methods are briefly presented. The suitability of various printing techniques to print selected polymeric materials and packaging materials is discussed. Because substrate properties are the primary factors that determine the printability of polymers bases such as films, multilayer films, semirigid and rigid plastic sheets, molded products, synthetic papers, and polymer-coated boards are described. In the case of these nonabsorbent materials, the key factor that determines printability is their surface free energy, which has an impact on material wettability and adhesion of ink to the substrate. All these problems, as well as the most important points related to print quality, are presented in this chapter. At the end, some facts about the plastic printing industry are included.

Applications of Printed Materials

This chapter is devoted to the applications of printed polymer materials. Although packaging is the main area of their application, printed electronics is the most recent and the quickest developing area. Flexible and rigid packaging is used in food products, personal protection, pharmacy, and in industries. The directions of the packaging market development in the upcoming years are also presented. The print is very often not made directly on the packaging. In such cases, the labels are used. The market of printed products and their application have been analyzed. Moreover, the most significant topics on electronic elements production on polymer substrates have been scrutinized. At the end, there is a presentation on the application of printed materials used in home equipments, advertisement gadgets, and other areas.

8 – Corona Treatment

This chapter describes a method of polymer treatment with the use of corona discharge. This is the most common industrial method to improve the wettability of nonabsorbent printing substrate before printing processes or to improve its properties before laminating or metalizing. This chapter describes treatment process and devices, as well as the factors that influence the effectiveness of modification. This chapter also characterizes the changes that occur on the upper layer of material, as a result of corona treatment, as well as the methods used to determine their characteristics. Based on the results of own research on polylactide (PLA) films, there is a presentation of application for surface topography examination, surface chemistry, and wettability to determine changes occurring in polymers during corona discharge and their impact on printability of this substrate. There is also a wide review of literature that was the basis for describing the changes resulting from treatment of polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, ethylene vinyl acetate, and PLA.

11 – Flexographic Printing

In this chapter, the flexographic printing technique is described. This technique is constantly developing and gaining in meaning. Flexographic printing is an example of relief printing that is useful for printing on both absorbent and nonabsorbent bases. It is crucial for the printing of plastic substrates with a wide range of inks: water-based, solvent-based, and ultraviolet-curable. Printing is done by using a flexible plate mounted on a printing cylinder. The kinds of plates and techniques for preparation are described in this chapter. Also, the parameters characterizing the anilox roller and their meaning for print quality are presented. The printing machines used in flexography and printing units are characterized. This chapter also specifies printing inks used in flexography and polymer bases that are commonly printed with this technique and describes the flexographic printing market.

Aging and Degradation of Printed Materials

This chapter is dedicated to the issues of aging and degradation of printed polymeric materials and the changes occurring in the polymers. First, the concept of aging and degradation is explained. Then the method of accelerated aging is described. Furthermore, the types of degradation and changes in polymeric materials caused by different types of processes are presented. Consequently, the test methods that can be used to study the degradation of polymer substrates as well as examine the changes in the prints due to aging are described. The remainder of the chapter presents the results of aging and degradation of the various polymers used as printing substrates and prints made on films.

Multilayer Polymer Films

A single polymer cannot meet all the required properties such as high impact, high stiffness, good heat sealability, stretchability, optical properties, barrier properties etc. of many of the end use polymer products. To compensate these properties a multilayer structure offers a good blend of properties. The whole is more than the sum of its parts properties. Multilayer films could be a natural choice for both rigid and flexible materials. Plastic films compose a broad category of materials that can be relatively simple or complex depending on the demands of a particular product. Multilayer polymer films usually composed of two or more different compositions and possess a thickness of up to about 7.5–8 × 10−4 m. The layers are at least partially contiguous and preferably, but optionally, coextensive.