RESEARCH AND STUDY OF THE USE OF SUSTAINABLE FINISHING PROCESSES

by Beatriz Domenech

R+D Projects

20th of February 2020

Global clothing sector output stands at 100 billion garments annually, causing huge environmental problems throughout the manufacturing chain. The supply of raw materials, the production and use of chemical products and water, atmospheric emissions and waste generated in the production and post-production phases are compromising the natural balance of ecosystems.

Society and in particular the textile sector, are becoming increasingly committed to sustainable manufacturing to develop fabrics and chemical-free products using natural products and using renewable materials. These efforts will prevent as far as possible, the use and contamination of water and air, protect the soil, reduce waste and save energy to help decrease global warming.

AITEX’s Technical Finishes, Environment and Health Research Group, together with manufacturers has been investigating different eco technologies and the use of natural products, analysing the advantages and limitations they represent.

The main objective of this project is to research different eco technologies in pre and post-dye treatment using natural dyes to develop new products for the clothing and habitat sector, while analysing, demonstrating and measuring the advantages that these technologies offer over traditional technologies. To achieve the main objective of the project, it was decided to divide it into different secondary objectives according to the technology used, establishing a series of expected results, which were fulfilled throughout the project and described below

• A study of the possible effects of dyeing using natural dyes with the micronising technique that minimises the consumption of water and chemicals and eliminates spillage.

The combination of dyes and auxiliaries of natural origin and with sustainable process technologies turns out to be a valid ecological alternative when compared to traditional production processes. Homogeneous and reproducible dyes using micro misting technology and the use of dyes of natural origin. Creating a range of colours by varying mordents, blends of unit dyes and trichrome staining.

Captura

Fixing natural plant dyes on fabrics and garments by batch dyeing, obtaining a representative and wide ranging palette to meet fashion trends, developing formulations and prototypes using different mordents; Alumbre Potassium, Aluminum Sulfate and Iron Sulfate; and different natural dyes such as Reseda, Chlorophyll, Acacia, Madder, Lac Dye or Logwood at different concentrations.

This was performed on fabrics of different compositions, (principally cotton and natural hide), to achieve reproducibility of dyes with the right physical properties.

• The use of different functional products (softeners, fluid repellent, antimicrobial, easy-care resins, etc.) in pre and post dyeing processes with natural dyes, to minimise water and chemical consumption, and zero spills using micronisation.

• The use of ozone technology as a pre and post treatment process for different natural fabrics dyed with natural dyes, achieving more intense colours through pre-treatment with ozone and dyeing with natural dyes, as well as washed out effects in the post-treatment process of different textile substrates dyed with the dyes. This considerably reduces water and energy consumption while eliminating the need for toxic processes and the use of permanganate.

The development of multilayer articles by calendering to laminate thermo-adhesive and special effect films. Ensuring that the application of high temperatures (around 170°C) does not affect the appearance or colour of the fabric. Avoiding excessive modification of the hand and drop of the fabric as well as its physical and fire retardant properties. Testing fabrics of different weights to confirm that the adhesive does not pass through the fabric at all.

• The use of corona plasma as a pre-treatment for materials that will be dyed with natural dyes using micronisation and batch dyeing using dry, environmentally friendly and cost-effective approaches, without manual operations or the use of chemicals. Improving aspects such as corrosion, hardness, wettability and adhesion without affecting the general properties of the fabric, improving the fabric’s affinity for natural dyes.

• The customisation of garments and fabrics using laser marking after dyeing with natural dyes, practically eliminating waste. Analysing the affects and reaction of the area marked in the dyeing process. It was observed that laser marking does not affect the subsequent process of dyeing with natural dyes, and that laser marking on pre-dyed fabric is reproducible.

• An evaluation of the advantages of each process (Life cycle analysis, carbon footprint), in a comparative analysis to check the environmental improvement in the category of Climate Change (Carbon Footprint) among 6 eco-sustainable textile processes compared to their traditional counterparts. The reduction of the environmental impact of processes when substituted for these eco-sustainable processes, as regards the global warming potential of each of the sustainable solutions compared to the traditional alternative. To calculate the Carbon Footprint of the different processes, the emission factors included in the 5th Evaluation Report of the United Nations Intergovernmental Panel on Climate Change (IPCC) have been used. This panel of experts is in charge of periodically assessing the global impact potential of the different gases emitted on our planet.

picture 1

After completing the different lines of work in the project and their respective characterisations, even better results were achieved than when using traditional finishing processes, including the improved versatility offered by some of these new eco processes compared to traditional approaches.

The comparative study of eco-sustainable processes versus traditional ones, carried out in accordance with the UNE-CEN ISO / TS 14067 standard “Greenhouse gases. Carbon footprint of products. Requirements and guidelines for quantification and communication” concludes that that the eco-alternatives reduce carbon footprints with environmental impact compared to conventional alternatives by between 30% and 99%, using micronized dyeing with reactive dyes and hydrophilic pre-treatment respectively, as can be seen in the table below:

picture 2

Te puede interesar