纺织品的数码印花

Write by Dr John Provost,对纺织品上的数码印花做出深入分析,值得纺织品数码印花人的阅读

INK JET PRINTING ON TEXTILES

Dr John Provost

Abstract

With the increased pressure from developing textile markets in the Far East the textile printer in Europe, Japan and the USA must respond with both increased quality and shorter time of response.

This means supplying new design concepts, sample and production printed fabrics in a wide range of colour ways in a time frame unheard of a few years ago.

One area that has seen development is in the pre-printing area with increasing use of CAD/CAM systems and digital printing systems ,with ink jet printing systems being targeted .Since the 1991 ITMA digital textile printing systems have been available that can be used for proofing and small sample production . A considerable number of major research projects ( in Europe , Japan and the USA ) aimed at taking digital textile printing to the full production scale are underway .

The present paper will review the latest development in the digital ink jet printing of textiles and highlight the future direction this technology will take in textile printing.

Introduction

The textile printing business is a large and complex business with production of prints required on all textile substrates from cotton to the wide range of synthetic fibres. Each of these fibres has to be printed with a dyestuff class to enable fixation (by various chemical or physical methods) to the textile to impart the 'wash and wear' characteristics demanded by the consumer.

Total production of textile prints approaches 19 linear billion metres of fabric per year and shows an average growth rate of the order of ~2% per year.However, hidden behind these small growth figures are a relative decline in the developed Western textile printing markets and a much larger growth in the developing markets in the Far East.

For the Developed print markets to survive into the 21st century a strategy has to be developed based on (i) speed of response, (ii) short lot production, (iii) short delivery times, (iv) increased innovation and new fashion ideas, and (v) the formation of 'partnerships' with the major retail groups (the printers' customer).

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Write by Dr John Provost,对纺织品上的数码印花做出深入分析,值得纺织品数码印花人的阅读

To achieve this strategy the printer must take an integrated approach to the whole textile printing process ( design /proofing and production ) (1).

The printer has to examine:

* the pre-printing stage (CAD/CAM)

* the quicker production of sample prints (using digital printing technologies whether direct ( ink Jet ) or indirect ( transfer technologies )

* selection of a compatible dye range to ensure minimum transfer from sample to bulk

production and consequent less down time when designs are proofed /sampled on digital systems before being printed on analogue systems .

The first two steps, the use of CAD systems and the quick production of sample prints are the 'key' starting elements of this strategy. It is in this area that we have seen rapid developments in the use of ink jet printing techniques using the digital output from CAD systems.

The major reason for the concentration of research programmes on ink jet printing is the

realisation that dyes used in digital technologies could be modified and adapted from the same dyes used in current conventional screen textile printing. It should therefore be possible to develop new systems, initially for 'proofing /sample' printing ,that would eliminate the need for preparing full separations and engraving. The technology is advancing at a rapid rate with

machines available up to the 100 square metre /hour level with further advances expected at the 1999 ITMA in Paris and over the subsequent next 5 years .

Full scale production machines which will replace conventional analogue systems are still many years away .

The development of full size ink jet print systems is the target of a number of ambitious plans with projects both in Europe ,USA and Japan.

Pre Print Stage in Textile Printing

If we examine the production time scale of a textile print from design conception to bulk print we can see the considerable advantages to be gained from design selection and sampling using ink jet print technology. To obtain a "feel" for the production time scale of a textile print let us examine the situation for a totally manual approach to the production of a textile print. Figure 1 gives an overview of the stages carried out in the production of a textile print.

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Write by Dr John Provost,对纺织品上的数码印花做出深入分析,值得纺织品数码印花人的阅读

CONVENTIONAL TEXTILE PRINTING PRODUCTION

Figure 1 Textile Printing by Conventional Manual Methods

In conventional textile printing ,an original design was manually traced, films produced and individual screens or rollers engraved for each colour (i.e. if a textile design has 24 colours then 24 screens have to be produced unlike the CMYK process colour system used in the graphic arts industry). A 'proof' (or sample ) print was produced in a number of colour ways on the textile substrate supplied by the customer prior to submitting to the customer for approval..

The time scales indicated in Figure 1 are still typical of those currently achievable by the textile printer who has not adopted digital technologies . However over the last few years there has been considerable investment by the printer and the majority of textile printers now have CAD systems.

With the right investment the printer can scan designs into a CAD system where he can reduce the number of colours, manipulate designs, put into repeat, colour and produce separations. The digital information produced can then subsequently be used to produce screens directly, via the latest laser engraving technology, or by conventional means using computer produced films.

However, the 'rate determining step' and major bottleneck is the production of the many colour ways at the sample print stage. Digital printing technologies can reduce these bottlenecks

considerably. These new technologies can reduce the time taken for colour way/sample selection and have greatly increased the efficiency of the printer in bringing design concepts to the market place.

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Write by Dr John Provost,对纺织品上的数码印花做出深入分析,值得纺织品数码印花人的阅读

This has consequently led to much more increased research activity in the field of textile ink jet printing . Integration of an ink jet printing system into the already available digital technologies( CAD, Laser Engraving etc ) would give the possibility of shortening the time to market dramatically .

A future scenario is shown in Figure 2 ,where the acceptance of the sample by the customer is made on the basis of an ink jet print . This is not a full reality at present , however with possible developments it could well become a possibility.

SAMPLE ACCEPTANCE

BULK PRODUCTION1-3 DAYS2 WEEKS

Figure 2 Possible Future Scenario for Sample to Bulk Production

The first systems were developed as long ago as the 1970’s ( the ICI /CCL continuous ink jet developments) (2) . Although there were a number of ambitious programmes over the subsequent years, it was not until the early 1990’s that programmes in Europe and Japan produced commercially available systems .

Although the current paper is concerned with ink jet printing for textiles with consequent

requirement for fine jet technology there were major developments in the carpet industry during those early years of digital printing .Two commercial systems were developed , the Millitron system (3) which uses an array of jets with continuous streams of dye liquor which can be deflected by a controlled air jet and the 'ChromoJet' system ( from the Zimmer Comapany of Austria (4).

Both these systems offer only coarse resolution which has not proved acceptable to the textile printer. However , they did indicate the many benefits of adopting ink jet printing technologies .

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Write by Dr John Provost,对纺织品上的数码印花做出深入分析,值得纺织品数码印花人的阅读

For sample and proofing purposes Stork of Holland introduced the 'Trucolor' TCP system at the 1991 ITMA exhibition in Hanover (5).

The Stork system is system is based on the Hertz binary continuous jet system (6). A full description of the principles can be found in the paper by Hertz and Samuelson (7).

Over the last 25 years there have been many projects in the textile ink jet field . These projects have used in many cases differing print head technologies . It is significant in the textile printing field that no one single print head technology has become established . The complete range of print head technologies are currently being researched by the many published projects .

An excellent review of textile ink printing has been published by Dawson (2).

Textile projects in jet printing have been considerable over the last 25 years , some of the major projects are listed below .

? Continuous Multi-Level Deflected Technology

? C.S.I.R.O (Australia )

? TOXOT (Image)

Zimmer ( Jemtex Print heads )

? Continuous Binary Systems

? Burlington Project (10)

? Amethyst (STORK) (5)

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