The world of nonwovens
Introduction to nonwovens
At NIRI, initial discussions often start with the very simple question, “What is a nonwoven material?”.
And as with most things relating to advanced materials and textiles, the answer isn’t always a simple one. In the following article we’ll try to break down the true definition of a nonwoven material is, the different types on nonwovens, how they differ from traditional fabrics, how they are produced and what their applications are.
We will also discuss the environmental impact of nonwovens and what the future may hold for the nonwoven sector.
The true definition of a nonwoven
A nonwoven material is a type of fabric that is made from fibres that are bonded together through a mechanical, chemical, thermal, or solvent treatment process. Unlike traditional fabrics, which are created by weaving or knitting fibres together, nonwoven materials do not have a specific pattern or structure and are often more flexible and porous than woven or knitted fabrics. This makes them suitable for a wide range of applications, from medical products to filtration systems – a topic we will cover within this article.
“A nonwoven is an engineered fibrous assembly, primarily planar, which has been given a designed level of structural integrity by physical and/or chemical means, excluding weaving, knitting or paper making.”
The definition according to ISO Standard 9092
How do nonwoven materials differ from traditional fabrics?
Nonwoven materials are not made from fibres that are woven together like traditional fabrics. Instead, they are made by bonding together fibres using mechanical, chemical, heat or solvent treatment. This makes them strong and durable, but also gives them a different feel, texture and appearance than traditional fabrics.
Below are some examples of how nonwovens differ from traditional fabrics:
- Production process: Traditional fabrics are made by interlacing yarns or fibres to create a woven or knit structure, while nonwoven materials are made by bonding fibres together using mechanical, thermal, or chemical means.
- Structure: Traditional fabrics have a distinct woven or knit structure, while nonwoven materials have a random, interlocking structure.
- Composition: Traditional fabrics are typically made from fibres that are spun into yarns, while nonwoven materials can be made from a wide range of fibres, including natural fibres, synthetic fibres, and recycled materials.
- Properties: Nonwoven materials tend to be stronger, more absorbent, and more flexible than traditional fabrics, but they may not be as soft or as durable.
- Uses: Nonwoven materials are used in a wide range of applications, including medical products, personal care products, construction materials, and industrial products. Traditional fabrics are used in a variety of applications, including clothing, bedding, and home furnishings.
“A nonwoven material is a type of fabric that is made from fibres that are bonded together through a mechanical, chemical, thermal, or solvent treatment process.
The Nonwoven Trinity
Nonwoven materials can be broadly divided into three categories:
Drylaid, Wetlaid, and Spunlaid
Drylaid materials are typically derived from textiles, while wetlaid materials are derived from papermaking processes. Spunlaid products, on the other hand, are typically derived from polymer extrusion and plastics. However, it should be noted that there are always exceptions to these generalisations.
The process of creating nonwoven fabrics involves forming a web from fibres or continuous filaments, followed by bonding to stabilise the structure. This may be followed by fabric finishing to alter the fabric’s properties, and finally converting, which refers to the processes used to transform nonwoven roll goods into finished products.
The drylaid category of nonwoens originates from the textile industry, and manipulates fibres in their dry state. The most common drylaid process involves carding fibres to create a web and then bonding the fibres using methods such as needle punching, thermobonding, chemical bonding, or hydroentanglement which uses high-pressure water jets. The first drylaid systems were based on the felting process which is believed to have originated in the Middle East and was later adopted by cultures in Europe and Asia. Felting is one of the oldest known methods of fabric production, with evidence of felted fabrics dating back to ancient civilizations.
Airlaying technology, also known as airlaid web formation, involves manipulating fibres in their dry state, but it originated from the paper industry. It involves converting wood pulp or synthetic fibres into low-density absorbent webs using air instead of water to transport the fibres. Some airlaying systems are capable of handling longer natural or synthetic fibres.
A wetlaid nonwoven is a type of fabric that is produced using the wetlaid manufacturing process. This process involves suspending short fibres in water and using machinery to manipulate the fibres into a web. The web is then pressed to remove excess water and bonded using mechanical, thermal, or chemical means.
According to the European Disposables and Nonwovens Association (EDANA), a material is classified as a wetlaid nonwoven if it contains more than 50% by mass of fibres with a length to diameter ratio greater than 300, or more than 30% fibre content for materials with a density less than 0.40g/cm3. This definition may differ from other standards and should be considered when determining the classification of a wetlaid nonwoven material.
Spunlaid (or spunmelt) nonwovens are a type of nonwoven fabric made by bonding fibres together using mechanical, thermal, or chemical means. They are produced by laying down a web of fibres and then bonding them together using one or more of these methods.
Spunlaid nonwovens are known for their strength, absorbency, and versatility, and are used in a wide range of applications, including medical products, personal care products, construction materials, and industrial products.
“Using recycled or biodegradable materials and implementing sustainable production practices can help to minimise their environmental impact, and these are key areas that NIRI looks to innovate and drive change across the nonwoven sector.“
What are the environmental impact of nonwovens?
The environmental impact of nonwoven materials depends on the specific materials used and the processes used to produce them. Some potential environmental impacts of nonwoven materials include:
- Water use: Nonwoven production processes can be water-intensive, particularly wetlaid processes that use water as a solvent.
- Chemical use: Some nonwoven production processes use chemicals such as solvents, resins, and adhesives, which can have environmental impacts if they are not properly managed.
- Waste generation: Nonwoven production processes can generate waste in the form of scrap material, trimmings, and process water. Proper waste management is important to minimise the environmental impact.
- Energy use: Nonwoven production processes can be energy-intensive, particularly those that use heat or mechanical processes.
- Carbon footprint: The production of nonwoven materials can contribute to greenhouse gas emissions, particularly if fossil fuels are used as an energy source – as we move away from the use of fossil fuels, the case for the use of nonwovens will only increase.
- Land use: Nonwoven materials may be produced from natural fibres such as cotton or wool, which can have environmental impacts related to land use and water use in their cultivation.
It is important to consider the environmental impacts of nonwoven materials throughout the entire life cycle, from raw material extraction and production through disposal or recycling. Using recycled or biodegradable materials and implementing sustainable production practices can help to minimise their environmental impact, and these are key areas that NIRI looks to innovate and drive change across the nonwoven sector.
What efforts are being made to improve the sustainability of nonwoven materials?
There are a number of efforts being made by the team at NIRI and the wider industry to improve the sustainability of nonwoven materials. Some of these efforts include:
- Using recycled materials: Many nonwovens are made from recycled materials such as post-consumer plastic bottles or recycled fibres from clothing and textiles. Using recycled materials reduces the demand for virgin raw materials and helps to minimise waste.
- Using biodegradable materials: Some nonwovens are made from biodegradable materials such as plant-based fibres, which can break down naturally in the environment. These materials can help to reduce the environmental impact of nonwovens at the end of their life.
- Implementing sustainable production practices: Many nonwoven manufacturers are implementing sustainable production practices such as reducing water use and minimising waste and chemical use. These practices can help to reduce the environmental impact of nonwoven production.
- Developing biodegradable and compostable nonwovens: Research is being conducted to develop nonwovens that are biodegradable and compostable, which could significantly reduce the environmental impact of nonwovens at the end of their life.
- Promoting the use of sustainable nonwovens: Many organisations, such as the International Association of the Nonwoven Fabrics Industry (INDA), are working to promote the use of sustainable nonwovens and educate consumers about the environmental benefits of these materials.
Overall, efforts to improve the sustainability of nonwoven materials focus on reducing the environmental impact of nonwoven production and increasing the use of environmentally friendly materials and practices.
What are the potential future developments in the world of nonwovens?
It is an exciting time to incorporate nonwovens into your products. There are several key developments in the field of nonwovens that are currently being researched or are expected to emerge in the coming years. These developments include:
- Biodegradable and compostable nonwovens: Research is being conducted to develop nonwovens that are biodegradable and compostable, which could significantly reduce the environmental impact of nonwovens at the end of their life.
- Smart nonwovens: Nonwovens with embedded sensors and other electronics are being developed for use in a variety of applications, such as healthcare, agriculture, and construction. These “smart” nonwovens could have a range of applications, including monitoring vital signs, detecting pests or diseases, and tracking structural integrity.
- Sustainable materials: Efforts are being made to develop nonwovens made from sustainable materials such as plant-based fibres and recycled materials. These materials can help to reduce the environmental impact of nonwovens and increase their sustainability.
- 3D printing of nonwovens: Research is being conducted on the use of 3D printing technology to produce nonwovens, which could allow for the customisation of nonwoven products and the production of complex shapes and structures.
- Intelligent nonwovens: Nonwovens with intelligent properties, such as the ability to change colour or shape in response to stimuli, are being developed for use in a range of applications, including fashion and interior design.
Overall, the future of nonwovens is incredibly bright. Innovations are likely to involve the development of materials and technologies that are more sustainable, intelligent, and customisable, which could have a range of applications across almost every industry.
NIRI are at the forefront of these developments and we are keen to collaborate with partners and clients that have the same desire for change and innovation.