Printing on Polymers

Fundamentals and Applications

Joanna Izdebska-Podsiad?y,Sabu Thomas

• Publisher: William Andrew
• Year: 2015
• ISBN:
  9780323375009
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Printing on Polymers: Fundamentals and Applications is the first authoritative reference covering the most important developments in the field of printing on polymers, their composites, nanocomposites, and gels.

The book examines the current state-of-the-art and new challenges in the formulation of inks, surface activation of polymer surfaces, and various methods of printing. The book equips engineers and materials scientists with the tools required to select the correct method, assess the quality of the result, reduce costs, and keep up-to-date with regulations and environmental concerns.

Choosing the correct way of decorating a particular polymer is an important part of the production process. Although printing on polymeric substrates can have desired positive effects, there can be problems associated with various decorating techniques. Physical, chemical, and thermal interactions can cause problems, such as cracking, peeling, or dulling. Safety, environmental sustainability, and cost are also significant factors which need to be considered.

With contributions from leading researchers from industry, academia, and private research institutions, this book serves as a one-stop reference for this field—from print ink manufacture to polymer surface modification and characterization; and from printing methods to applications and end-of-life issues.

• Enables engineers to select the correct decoration method for each material and application, assess print quality, and reduce costs
• Increases familiarity with the terminology, tests, processes, techniques, and regulations of printing on plastic, which reduces the risk of adverse reactions, such as cracking, peeling, or dulling of the print
• Addresses the issues of environmental impact and cost when printing on polymeric substrates
• Features contributions from leading researchers from industry, academia, and private research institutions

1

Printing on Polymers

Theory and Practice

Joanna Izdebska Department of Printing Technology, Faculty of Production Engineering, Mechanics and Printing Institute, Warsaw University of Technology, Warsaw, Poland

Abstract

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.

Keywords

Plastic substrates; Print quality; Printability; Printed polymers; Printing techniques; Surface-free energy; Surface wetting

Outline

1.1 Introduction—The Impact of Printing 1

1.2 Printing Techniques 2

1.2.1 Flat Printing 3

1.2.2 Relief Printing 4

1.2.3 Gravure Printing 5

1.2.4 Stencil Printing 5

1.2.5 Digital Printing 6

1.2.6 Three-Dimensional Printing 7

1.2.7 Hybrid Printing 7

1.2.8 Various Printing Techniques for Polymer Decoration 7

1.3 Printing Bases 7

1.3.1 Films 9

1.3.2 Multilayer Films 10

1.3.3 Semirigid and Rigid Plastic Sheets 10

1.3.4 Injection Molded Products 11

1.3.5 Synthetic Papers and Polymer-Coated Boards 11

1.4 Printability 11

1.5 Surface Wettability 12

1.5.1 Surface Tension of Inks 12

1.5.2 Surface Free Energy of Printing Substrates 13

1.5.2.1 Devices for Measurement of the Contact Angle 13

1.5.2.2 Measurement Liquid, Pens, etc. 14

1.6 Print Quality 15

1.6.1 Factors of Printing Processes Influencing the Print Quality 15

1.6.2 Impact of Ink and Substrate Properties on the Print Quality 15

1.6.3 Parameters Used in Quality Assessment 16

1.7 Plastic Printing Industry 17

References 18

1.1. Introduction—The Impact of Printing

The history of European printing is relatively short, as it dates back to the fifteenth century. At that time, Gutenberg began with printing using a press and movable types. However, attempts to record important information and events or attempts to decorate materials including ceramics have taken place since the dawn of the human history. Fired clay tablets or wooden stamps were used for this purpose. However, it was Gutenberg's invention that was considered the beginning of the development of printing techniques, multiple duplication of the same picture from the form on the printing substrate using ink (Gregory, 1996; Kipphan, 2001).

The first printing substrate was paper, and it is still a dominant one. However, very diverse properties of plastics led to the situation in which they started to play an important role in various areas, including as printed materials. In 1912, when cellophane film (made of regenerated cellulose) started to be produced on a mass scale, its transparency and barrier properties were first used. It was not until the 1930s that cellophane began to be used as a printing substrate for multicolor printing (Gurwick, 1932). Another stage in printing of plastics was the emergence of the first plastic films in the 1950s, which were petroleum derivatives. This event has revolutionized the packaging industry as well. Packaging is a major group of plastic materials. Further application areas are shown in Figure 1.1. Transparency of materials, which gives a whole range of promotion opportunities of a packaged product and various barrier properties, resulted in the fact that plastics and, in particular, films are commonly used for packaging manufacturing, both in the form of monofilms, and as multilayer compositions combined with paper and aluminum films.

Figure 1.1 Areas of plastics application in 2013. Source: Own elaboration on the basis of the data (Plastics Europe, 2015).

The largest group of packaging is food packaging, and among these, the most important group is flexible packaging with paper as a forerunner. The advantage of flexible packaging manufactured from plastic over paper packaging, inter alia, depends on better protection against moisture, higher tear strength, a relatively lower price, and the possibility to use modern packaging systems as well as a better product presentation.

Modern packaging is designed to protect the packaged product, promote it, and facilitate its use. Therefore, almost every package requires minimum printing information, although much higher requirements are imposed on the majority of them. Nowadays, when shelves are overfilled with products, packaging plays an important role while shopping. Performance esthetics, unique shape, color schemes, or other visual elements can tempt a hesitant customer to buy a given product. The marketing function of packaging is closely connected with the printing process and print quality. However, printing on plastics means not only printing on food, cosmetic, or industrial packaging, but also printing on everyday objects, electronics, medical devices, sports equipment, advertising gadgets, polyester fabrics, etc.

Multicolored, high-quality printing on plastic material can be made only by appropriate selection of printing techniques and their parameters as well as the type of ink used for a given substrate. Due to the variety of materials available on the market, it is estimated that there are currently >700 types, which are divided into several groups (Plastics Europe, 2014). A knowledge of printing techniques and process requirements concerning the substrate or quality control is thus necessary. The subsequent chapters of this book discuss all these issues.

1.2. Printing Techniques

According to the encyclopedic definition (Rosato, 2000), printing is a method used for decoration and execution of marketing objec...