Improving development of sustainable hygiene products using specialty viscose fibers.
One area of hygiene – women’s sanitary products – is trending towards more sustainable consumer options and is being fueled by Generation Z’s push for reuse and recycling options that lessen the impact of human impact on the environment. One area of central focus at Kelheim Fibres GmBh used the example of a “menstruation panty” in a recent study to seek viable options for the marketplace. The team’s spokesperson, Natalie Wunder, shared their solution at the recent Dornbirn Global Fiber Congress in Austria, and here are their findings.
Seeking Environmental Options
Kelheim Fibres GmbH is a leading supplier for fibres used in menstruation hygiene products. However, conventional menstruation products like sanitary pads, which are made from petrochemical raw materials, lead to a huge amount of non-biodegradable and non-recyclable waste. Therefore, it is necessary to engage in the development of more sustainable solutions. Here the development of reusable menstruation pants mainly based on renewable cellulosic raw materials is described. In order to get to know the existing market for period pants a competitor product analysis of ten brands from the core markets in Europe and North America was carried out.
Simultaneously different cellulosic fabric materials were tested. The acquisition time and the rewet value of the products and material samples were tested. The best market product showed an outstanding performance but has drawbacks concerning the physical properties of the pants. The material tests showed that the performance is dependent on both the material composition as well as the material structure.
The most promising results showed Danufil® fibres in the Topsheet, Galaxy® in the Acquisition distribution layer (ADL) layer, Bramante, a hollow viscose fibre, in the Absorbent Core. Further work is planned to optimize the composition and the knitting structure of the individual layers and create a commercial product together with partners.
Hygiene products are used in a variety of forms and applications, like menstruation management or incontinence and baby care, every day by millions of people worldwide. That conventional petroleum-based single-use products have a negative impact on the environment is well-known and initiatives like the Single Use Plastic Directive of the European Union (EU) are a driving force to create more sustainable products (European Parliament, 2019). In addition to that the market for more sustainable, and reusable products in the hygiene area is growing in recent years. Currently available sustainable alternatives are reusable but have the drawback that they are usually made from different components including synthetic materials. As a result, the products are hard to recycle and not fully biodegradable and therefore, after their lifetime, contribute to the growing amount of textile waste. This article aims to showcase how a fully sustainable and biodegradable hygiene product can be developed with predominantly cellulose-based raw materials using the example of a menstruation panty.
Menstruation is a topic that affects half of the human population on Earth at a certain time of their lives, which equals 3,865 billion people (United Nations, 2019). On average, the amount of blood lost varies between 20 and 60 ml, (Mengel, 2020). As the subject of menstruation is still stigmatized, adequate communication is hard to achieve. As a result, informed choice of the product selection is not possible for a huge number of women and single use menstruation products are frequently disposed incorrectly leading to environmental pollution. In 2017, 49 billion sanitary menstruation products that equal 590,000 tons were used alone in the 28 member states of the EU (Van den Bossche, 2020). In addition to that, single use sanitary pads are on average made of 90% of synthetic materials (Van den Bossche, 2020) In Germany, the predominantly used menstruation products are tampons used by 71% of women, followed by pads with 62% according to a study conducted in 2020 (Sparwelt GmbH, 2020). Only 7% of the study participants use sustainable alternatives (Sparwelt GmbH, 2020).
The problems that could be identified for commercially available reusable menstruation products through a competitor product test are the usage of various synthetic fiber materials in the products which can lead to microplastic emissions during the home laundering process, the usage of biocides and that a good performance can only be achieved by compromising the comfort of the product. As a result, the aim in the development of a concept for a sustainable menstruation panty was to combine the three aspects of comfort, performance and sustainability in one product.
The competitor product analysis rates the products against each other in the categories shown in table 1. The categories’ performance and sustainability are graded double as they are the main interest of this paper. The worst product is rated with 10 and the best product with 1 point. The test has been performed in 2021 and the tested products were selected out of the main markets of Europe and North America.
The test method used for the evaluation of the performance was an adaption of the acquisition time and rewet test that measures the time a certain amount of liquid takes to be absorbed by the tested specimen and the amount of liquid that is given back to a filter paper form the tested specimen under the pressure of 1 kg. The target is to keep both values as low as possible. For the competitor product test liquid amounts of 10, 15 and 20 ml were used. The material tests were carried out with a defined sample size of 15 x 8 cm and a liquid volume of 10 ml. In addition to that, the thickness, the air permeability and the weight of all samples were measured in order to gain information on wearing comfort.
The final rating of the competitive product test can be seen in Table 1. The performance values of the winning German company are an average acquisition time of 3.73 seconds and an average rewet value of 3.77 g at a test liquid volume of 15 ml. It is also noticeable that there is a huge variance in all measured values of the period pants over the testing span of 26 washing cycles which equivalents two years of usage.
The concept of Kelheim Fibres sustainable menstruation panty can be structured into three parts: The fiber composition, the textile structure and the product assembly as shown in figure 1. A menstruation panty is structured into four different layers: the topsheet, the acquisition distribution layer, the absorbent core and the backsheet. To gain an ideal performance the interaction between the layers has to be adjusted correctly.
For the fiber composition the specialized viscose fibers Danufil®, Galaxy® and Bramante are used. The standard viscose fibre Danufil® is used in the topsheet. For the acquisition distribution layer the trilobal Galaxy® fiber is perfectly suited as the trilobal cross-section builds capillary channels and enhances the liquid transportation and wicking properties. In the absorbent core the segmented hollow Bramante fiber is used as it has a high-water retention capacity and can absorb liquids up to 200% of its own weight. As blending components for the specialized viscose fibers Viloft®, a flat but clowed shaped viscose fiber, and the standard viscose fiber Danufil® are perfectly suited. To find a sustainable material for the waterproof backsheet of the period panty presented a challenge. Suitable options are a bio-based and biodegradable polymer film, a sustainable waterproof coating or a special weaving technology.
In addition to that the textile layers are important. In the topsheet a single jersey knitted structure with integrated tucks can create a perforation effect and therefore decrease the acquisition time of the product. In the acquisition distribution layer, a double piquè knitted structure is best suited and in the absorbent core a pile-loop knitted structure creates enough space for the liquid absorption.
The third important part of the concept for a sustainable menstruation panty is the product assembly that can influence the performance of the product. By adding longitudinal seams in the absorbing area, the liquid distribution and absorption can be improved. Furthermore, a special waterproof seam design can prevent leakage and give the wearer more security. To fulfil aesthetic requirements the period panty can be designed without seams on the outside to look like normal underwear.
This concept for a sustainable period panty could already be transferred into a first prototype and the performance values can be compared to the performance of the average commercially available menstruation panty. The test results in figure 2 show that the rewet value could already be reduced by 43% and the acquisition time value by 10% compared to market products. However, reusable products are still not in the performance range of single-use menstruation products and the aim is to improve the performance and in the future. In addition to that Kelheim Fibres works together with partners to create a commercially available product.
The market potentials for a sustainable menstruation pant is high, as the menstruation pant market is expected to grow from a market volume of $79 million USD in 2018 (Jagtap, 2020) to the size of $180 million USD in 2021 (Future Market Insights, Department Consumer Product, 2021) and $580 million USD in 2025 (Jagtap, 2020). In addition to that, there are still countries in Europe that have not entered the menstruation pant market yet and could hold a potential for growing sales volumes. Especially Italy and the Scandinavian countries can be important in the next years. As mentioned before, the Single-Use Plastic Directive (SUPD) can also be a driving force for more sustainable menstruation products on the European market. Outside of the core markets, China and India are expected to have a huge potential for period pants. However, when implementing reusable products like period pants it is important to educate the users accordingly on how to wash and clean them. As menstruation is highly stigmatized in these countries a risk can be seen for inadequate cleaning and drying of the product which might lead to increased bacteria growth.
The development of sustainable menstruation pants using predominantly biodegradable and renewable materials is a promising application that should be investigated further to minimize waste and to create a circular approach. However, it is important not to compromise on performance and comfort. The before described composition represents menstruation pants that combine sustainability, comfort and performance. The product is designed industrially biodegradable and can be seen as an example for a circular textile product. This path should also not only be limited to period pants and reusable products but can be transferred to products in the incontinence and diaper market as well as to other textile applications in the reusable and single-use sector. Kelheim Fibres wants to contribute to a more sustainable and fair world and supports informed product selection for all customers without having to compromise on sustainability. As a result, research on how to produce more sustainable reusable and single-use products is carried out using the open innovation approach.