Indanthren Vat dyes offer superior fastness levels
Can fashionable clothes be sustainable? With the right production technology and expertise, sustainable products can be achieved by using better raw materials to produce higher quality products with better physical aspects, long-lasting fabrics, and colours. The current technologies offer a lot of possibilities and even existing options can be re-explored, such as DyStar’s lndanthren dyes, says Guido Krabbe, Global Product Manager of Vat Dyes and Paper, DyStar, in an interview with Fibre2Fashion.
Can you elaborate on the reproducibility of lndanthren recipes, and the relative dyeing process time compared to other dyes?
It is reasonable to compare Indanthren dyes with reactive dyes, the most commonly used dye class for cellulosic fibres. Vat dyes have higher exhaustion rates which makes reproducibility better to a considerable extent.
Generally, the Indanthren dyeing process is a bit more efficient. As time, efficiency and reproducibility are superior, the utilisation of Indanthren dyes presents tangible benefits in terms of savings, time optimisation, and the pursuit of efficient and sustainable textile production.
Can you explain the different types of textile dyes that are commonly used in the industry and their key characteristics?
There are multiple dye classes used in the textile industry.
Firstly, the type of fibre—such as polyester, polyamide, polyacrylic or cellulosic—determines the dye class. Additionally, the selection of the dye class may depend also on the application method, and finally the requirements and specifications of the final textile product – fashion, outdoor, sportswear, professional workwear, blinds, curtains, bed linen, towels etc.
As we know, the textile industry and textile articles are extremely diverse. DyStar is well-equipped to offer a comprehensive range of dye classes for all fibres and applications. Notably, our Indanthren dyes are suitable for cellulosic – and their blends with synthetic fibres.
How have advancements in dyeing technology impacted the sustainability of the textile industry?
Over the past decades, the whole textile dyeing and finishing processes have made significant strides towards a more sustainable way of producing textiles.
Certain textile dyes and chemical producers including DyStar, partnered with leading textile machinery manufacturers and dyeing mills. Such collaboration has gained substantial momentum in the recent years and is a key driver for innovation.
As an industry forerunner, DyStar’s experts developed the ‘Best Available Technology’ (BAT) concept aimed at reducing carbon footprint and minimising resource usage in the textile wet processing sector. We currently offer 10 Cadira modules to support our customers, brands and retailers and other stakeholders in the supply chain to save valuable resources.
How does the Cadira Vat process reduce the environmental impact and save resources during the dyeing process?
The Cadira Vat process combines the often-necessary pre-treatment and the soaping step. This integration is made possible by using special auxiliaries during dyeing, followed by combining post-bleaching with the soaping step. This methodology has been subject to rigorous assessment, affirming its reliability and performance.
As a result, the whole dyeing process is much shorter, leading to significant reductions in time, water and energy consumption.
Can you describe how the energy and water consumption of lndanthren dyeing compares to that of other dyes, particularly reactive dyes?
The energy and water consumption in dyeing processes can vary based on factors such as application methods and machinery used. But in general, DyStar’s Cadira Vat dyeing method provides a significant saving on energy and water consumption. This is attributed to the high exhaustion rates of Indanthren dyes. Thanks to these features, pre-treatment and after-treatment can be shortened significantly which provides the saving.
What are the main challenges in ensuring both the quality of the dyeing process and the environmental sustainability of textile dye production?
Ensuring the quality of our products is something that is non-negotiable. Both our quality application specifications and our eco-specifications – with respect to product safety, product eco-compliance, toxicology and other ecological aspects, are very advanced. Customers are assured that DyStar products not only meet technical excellence but also fully comply with regulatory and key voluntary standards. Sustainable dye and chemical production, coupled with stringent quality control parameters of our products is indispensable for DyStar.
What specific qualities make lndanthren dyes more suitable for fashion and sportswear than other available dyes?
The keyword here is ‘long-lasting’. Currently, reactive dyes are the major dye class for cellulosic fibres in the market, which DyStar offers a wide range under Levafix, Remazol and Procion product ranges. However, as mentioned before, Indanthren Vat dyes are an interesting alternative for cellulosic fibres. Between the two dye classes, the level of fastness performance is different, but in many aspects, Indanthren Vat dyes offer superior fastness levels.
Now and in the recent past, the industry’s principal topic often is ‘fashion for less’. Multiple fashion campaigns per year seduced the customer to buy more than necessary. Overall quality is by far not as important as price. As a result, the pre-and post-consumer waste (particularly in Western countries) is unbelievably high.
The textile industry is amongst the industries with the highest environmental impact.
Furthermore, textiles need to be recycled in future instead of landfilled or incinerated. As such, more challenges are expected ahead of us.
A mindset change is required, and it is indeed happening. We are starting to see many online shops where you can sell or buy second-hand clothing. The garment however must still be good-looking with no fading or other colour changes.
The Cadira Vat Module using Indanthren dyes and selected DyStar auxiliaries can be part of the solution to produce long-lasting fashionable wear with the highest possible fastness properties.
How are Indanthren dyes removed from wastewater, and how do they meet the stringent eco-specifications?
The so-called ‘exhaustion rate’ or degree of fixation of Indanthren dyes is very high.
Furthermore, Indanthren dyes in the effluent are water-insoluble and can be removed much easier than soluble dyes.
To meet stringent eco-specifications, DyStar employs the econfidence programme. The econfidence programme ensures that DyStar’s products meet regulatory standards and key MRSL/RSLs (Manufacturing Restricted Substance Lists/Restricted Substance Lists). This is communicated via our internet-based tool, eliot, a unique and free-of-charge tool that we offer to our customers, brands and retailers and other industry stakeholders.
Can you provide more insight into the econfidence programme and its role in maintaining product quality and environmental responsibility?
The econfidence commitment assures customers of the highest possible levels of product quality and environmental responsibility and is backed up by the most extensive eco-testing programme of any textile chemical supplier.
DyStar’s products are in full compliance with the applicable chemical legislation in the markets in which they are manufactured and sold. For example, all DyStar product components (over 5,000 individual chemicals had to be considered) have been pre-registered under the EU REACH Regulation.
Can you explain in more detail how the light, perspiration light, chlorine, weather, and multiple washing fastness of lndanthren dyes contribute to a longer product life cycle?
Indanthren dyes offer a compelling solution to extending the product life cycle of textile articles through their exceptional resistance to a range of environmental influences.
Whatever textile article you own, be is a pique shirt, a terry towel, trousers, or sportswear, as long as it looks good in terms of colour and you still like it, you will feel less obliged to buy a new one. Coloured textiles are constantly exposed to environmental influences that cause damage in terms of bleeding, fading etc. Indanthren dyes are more resistant than other dye classes and can withstand these influences for far longer.
Incorporating Indanthren dyes into textile production thus not only enhances the overall quality of products but also supports a more environmentally conscious approach to fashion due to the product’s longevity and durability.
What is the process through which lndanthren dyes migrate into fibres in their reduced, water-soluble form?
Indanthren dyes belong to the dye class Vat dyes, and in order to fix them onto cellulosic fibres, they need to be chemically reduced. Only in this form, the dyes show affinity to the cellulose.
Once the dyes have successfully migrated to, or better, into the cellulose, they are changed back to their original, water-insoluble form. This process is called vatting and oxidation. The dyes are captured in the cellulose and there is no chemical bond which can be broken. Instead, the dyes become encapsulated within the cellulose structure, ensuring their stability and resistance to external factors.
Could you explain the difference between the Indanthren Coll and Coll liq dyestuffs and how they meet different standards and certifications?
DyStar offers Indanthren dyes in two forms – as powder (Indanthren Coll) and as liquid form (Indanthren Coll liq). The dye concentration is different and in general, powder dyes are more concentrated. Mainly both forms have similar specifications in terms of shade consistency, strength, dispersion fineness etc. However, liquid dyes have a few more properties to be considered such as pH, viscosity, and sedimentation.
Whether a customer decides to work with powder or liquid forms is a very individual preference.
Despite these variances, both Indanthren Coll and Coll liq fulfil the same econfidence and application criteria.
How is the response to Indanthren dyestuffs, particularly in the fashion and sportswear industry? Are there any major barriers to their wider use?
Indanthren dyes are used for articles which require high fastness profiles such as professional workwear, medical textiles, and outdoor articles. Also, Indanthren dyes are being used for fashion articles such as yarn-dyed shirting fabrics.
However, despite their advantages, there are mainly two aspects which limit their wider use. One reason is the limited experience the dye and/or printing houses might have with these dyes. Sometimes, one considers that a faulty dyeing cannot be stripped like reactive dyes.
What opportunities for innovation and further development do you see in the area of Indanthren dye use and how it could contribute more to sustainability in the textile industry?
The landscape of innovation in Indanthren dye technology and chemistry appears to be moving beyond the creation of entirely new dye molecules. Instead, the focus is shifting towards developing advanced and better sustainable reduction possibilities during the dyeing and printing processes, including digital printing concepts and further process optimisations.
Cadira, DyStar, econfidence, eliot, Indanthren, Levafix, Remazol and Procion are registered trademarks of DyStar Colours Distribution GmbH, DE.
REACH is a registered trademark of the European Union, represented by the European Commission BE.
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