3D Dispensing of Waterborne Polyurethane on Textile

Special Article: Textile Printing

Adv Res Text Eng. 2023; 8(3): 1089.

3D Dispensing of Waterborne Polyurethane on Textile

Maximilian Scherf¹; Agnes Psikuta²; Julia Hemetzberger¹; Daniel Wittwer¹; Michael Wieser³; Viktor Weichselbaumer³; Thomas Schmidt4*; Leo Schranzhofer¹; Julia Kastner¹

1Functional Surfaces and Nanostructures, Profactor GmbH, 4407 Steyr-Gleink, Austria

2Empa Swiss Federal Laboratories for Material Technology and Science, 9014 St. Gallen, Switzerland

3yokai-studios GmbH, 4040 Linz, Austria

4Key Lab for Sport Shoes Upper Materials of Fujian Province, Fujian Huafeng New Matierals Co., Ltd., Putian, Fuijian, China

*Corresponding author: Thomas Schmidt Key Lab for Sport Shoes Upper Materials of Fujian Province, Fujian Huafeng New Matierals Co., Ltd., Putian, Fuijian, China. Tel: +86 136 1593 4792 Email: thomas.schmidt@huafeng-cn.com

Received: October 16, 2023 Accepted: November 15, 2023 Published: November 22, 2023

Abstract

The paper presents an investigation into the digital printing of waterborne Thermoplastic Polyurethane (TPU) ink using advanced dispensing technology. The study focuses on assessing the ink’s adhesion properties on four distinct textile substrates and explores the challenges and possibilities of applying this ink to curved textile geometries.

The research employed cutting-edge digital printing equipment to precisely dispense waterborne HAPTIC® ink onto polyester, cotton, and viscose textile. Adhesion testing was conducted to evaluate the ink’s performance on each substrate, considering factors such as elongation at maximal force. The results provide valuable insights into the suitability of waterborne TPU ink for various textile types, offering guidance for potential applications in the textile industry.

Furthermore, this study delves into the intricate process of digitally dispensing waterborne TPU ink onto curved textile surfaces. The investigation examines the challenges posed by irregular textile geometries, including curvature, elasticity, and stretchability, and explores innovative solutions for achieving consistent and high-quality printing results on such surfaces.

The findings of this research contribute to the advancement of digital printing technology in the textile industry, offering a deeper understanding of ink-substrate interactions and paving the way for new possibilities in textile design, customization, and manufacturing.

Keywords: Waterborne polyurethane dispersion; Dispensing; Additive manufacturing; Textiles

Introduction

Printing on textiles for decorative purposes was already used in ancient times. Several techniques have been used, changed and evolved with times. Nowadays screen printing is the most used technology in the textile printing industry. More than 90% of all printed textiles around the world are printed by screen printing processes including flat-bad, rotary and table screen printing where a flat or cylindrical screen is used to apply ink or paste on the fabric [1]. However, screen printing is a non-ecological way of using resources and is limited to flat substrates. Additionally, in the textile industry digital deposition techniques receive more and more attention due to reduction of waste, flexible production and freedom of design [2]. Methods for digital deposition include dispensing [3,4], valve-based inkjet [5], piezoelectric-based inkjet [6-8] and extrusion [9-11] or polyjet [11,12] based 3D printing. While 3D printing is very often connected to extrusion-based 3D printing (also known as fused filament fabrication, FFF), there are several methods to create to create structures onto textiles or even stand alone garments [13-15].

Polyurethane (PU) is one of the most common materials in the textile industry used for creation of protective and haptic structures [16-18]. Huafeng developed the HAPTIC® ink for screen printing for modifying textile surfaces in visual appearance, functional reinforcement and any haptic effects. HAPTIC® is a fully water-based PUD 2K system with isocyanate hardener. To be able to use this material in a digital process, in this work, the dispensing technology was used to deposit this material [4]. Additionally, the dispensing technique can combine mixing and material transport in a single process in a two-component (2K) dispensing device.

Adhesion of the printed or dispensed HAPTIC® material to the textiles is very important for most applications. Standard tests are bending or bally-flex tests [4]. The adhesion or bonding of the ink to the specific textile substrate is usually tested by gluing a strip of plastic material strongly onto the surface of the ink and then pulling the plastic stripe and the textile materials apart by a tensile testing machine. In most cases the ink will separate from the textile at certain pulling strength usually in a range of 25–50 N/cm. However, in some cases cohesion breakage or breakage of the textile can also be observed showing that the bonding of the ink is not the limiting factor for these products. The material properties of the pure HAPTIC® ink also play a key role and elongation of the PU resins is another important performance factor of the overall system. In most applications the HAPTIC® coatings are applied for decorative appearance and for improving abrasion resistance in certain areas as shown in Figure 1. Printing around half cylindrical sock-like 3D knitted textiles can provide an opportunity to reinforce the textile sock in the heel area of a shoe upper and providing better support to the fit of the shoe in the heel area.