Exploring Advancement in Some Key Areas of Technical Textiles

Introduction 

Technical textiles are specialized fabrics designed for functional purposes beyond traditional apparel and home furnishings. These textiles are engineered to exhibit specific performance characteristics such as strength, durability, flame resistance, chemical resistance, and moisture management, making them suitable for various industrial, medical, automotive, aerospace, and other technical applications. They play a crucial role in enhancing safety, efficiency, and sustainability across diverse sectors, including protective clothing, medical devices, geotextiles for construction, and advanced materials for transportation. The versatility and innovation in technical textiles continue to drive advancements in numerous industries, supporting a wide range of practical and high-performance applications.

1. Automotive Textile

1.1 Car seat and seat cover 

Car seats are designed to offer ergonomic support and safety features, such as adjustable headrests and lumbar support, to ensure a comfortable and secure ride. Seat covers, on the other hand, serve to protect the original upholstery from wear and tear, spills, and stains. They come in various materials, including leather, fabric, and synthetic options, each offering different levels of durability, comfort, and style.

Car seats must comply with safety regulations such as those set by the National Highway Traffic Safety Administration (NHTSA) in the U.S. or equivalent bodies in other countries. This includes crash testing and proper labelling for weight and height limits.

Composition of car seat

Tri-laminate consisting of face fabric, foam, and scrim lining on the back

• PET face fabric
• The foam is PE-PU or Polyether-PU, the latter being more hydrolysis resistant and suitable for humid climates.
• Foam density 26 to 45 kg/m³
• 2 to 22 mm thick, fire-resistant.
• The scrimp fabric is warp knitted (nylon or polyester), 30-90 g/m.²

These materials are selected based on their ability to balance comfort, durability, and ease of maintenance, ensuring that car seats meet the high standards required for automotive interiors.

• Abrasion Resistance
• Antistatic Properties
• Soil Resistance
• Strength and color fastness

Although PE-PU or Polyether-PU is widely used in car seat manufacturing, there are several issues associated with its use:

Environmental Impact: PU foam is difficult to recycle and contributes significantly to plastic waste. It is one of the least recycled materials, leading to long-term ecological concerns.

Health Risks: The production of PU foam involves chemicals like isocyanates, which can cause respiratory and skin irritation. Long-term exposure to these chemicals has been linked to more severe health issues.

Durability: Over time, PU foam can lose its shape and resilience, leading to sagging and reduced support. This can result in an uncomfortable seating experience and decreased ergonomic support.

Heat Retention: PU foam tends to retain heat, making car seats uncomfortable in hot weather. This can be particularly problematic in regions with high temperatures.

Off-gassing: New PU foam products can emit volatile organic compounds (VOCs), contributing to indoor air pollution, and can cause headaches, dizziness, and other health issues. 

Using spacer fabric instead of PU foam for car seats can offer several advantages and address some of the issues associated with foam.

Spacer fabric

Spacer fabric is a unique textile type made using a specialised manufacturing process. Its three-dimensional structure is characterised by two layers of fabric joined together by a layer of spacer yarns. The spacer yarns create a gap, or “spacer,” between the two layers of fabric, giving the material unique properties. The manufacturing process for spacer fabric involves using a circular knitting machine to create a tubular fabric with a continuous length of spacer yarn running through the middle. This tubular fabric is then sliced open, and the two layers are separated, leaving the spacer yarns in the middle. The result is a three-dimensional fabric with a soft, cushioned feel. Spacer fabric is known for its unique properties, which include breathability, moisture-wicking, and insulation. The spacer yarns in the middle of the fabric create a gap between the two layers, allowing air to circulate freely through the material. This makes wearing it highly breathable and comfortable in hot or humid conditions.

Additionally, the spacer yarns wick moisture away from the body, helping to keep the wearer cool and dry. In terms of insulation, the air trapped between the two layers of fabric creates a thermal barrier that helps to regulate body temperature. This makes spacer fabric an ideal choice for clothing and other textile products that provide warmth and protection in cold or harsh environments.

Properties

Breathability: The gap created by the spacer yarns allows for excellent air circulation, making the fabric highly breathable. This helps regulate temperature and moisture, keeping the user cool and dry23.

Moisture-Wicking: Spacer fabric can wick moisture away from the body, enhancing comfort during physical activities or in hot conditions.

Insulation: The air trapped between the two layers acts as a thermal barrier, providing insulation and helping to regulate body temperature.

Cushioning and Comfort: The 3D structure provides a cushioning effect, distributing weight evenly and reducing pressure points. This makes it ideal for applications requiring prolonged contact, such as car seats and mattresses.

Durability: Spacer fabric is resistant to compression and maintains its shape over time, ensuring long-lasting comfort and support.

1.2 Car Cabin Air Filter

A car cabin air filter is a component in a vehicle’s HVAC (heating, ventilation, and air conditioning) system that filters the air entering the cabin. It is typically a flat, pleated, rectangular cartridge made from a combination of nonwoven fabric or sometimes paper or mash. Conventional cabin air filters, while effective to some extent, have several drawbacks:

Limited Odor Control: They cannot often neutralize odors effectively, leading to persistent smells from outside sources like exhaust fumes and pollution.

Reduced Filtration Efficiency: Standard filters may not capture smaller particles, such as volatile organic compounds (VOCs) and harmful gases, affecting air quality inside the vehicle.

Activated carbon air filters offer a superior alternative to traditional car cabin air filters by not only trapping dust and pollen but also effectively absorbing harmful gases, odors, and volatile organic compounds (VOCs), thus enhancing the overall air quality within the vehicle’s cabin.

Activated carbon air filter with nonwoven fabric

Activated carbon air filters combined with nonwoven fabric are highly effective for air purification, as the activated carbon adsorbs pollutants, odors, and volatile organic compounds (VOCs). In contrast, the nonwoven fabric provides structural support and good air permeability. This combination is commonly used in industrial settings, home air purifiers, and HVAC systems to remove harmful gases like benzene, formaldehyde, and sulfur dioxide, enhancing overall air quality.

Construction

An activated carbon filter for the automotive cabin is formed using two layers of Meltblown fabric. The activated carbon is scattered on the bottom layer using a scattering unit with adhesive powder, which is heated using IR heating. The adhesive is subjected to melt covered by the top layer, followed by the calendaring process, as shown in the figure below.

Benefits of using activated carbon

Odor Removal: Activated carbon effectively absorbs and neutralizes unpleasant odors, ensuring a fresher cabin environment.

Gas Adsorption: It traps harmful gases like sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone, preventing them from entering the cabin.

Allergen Reduction: The filter captures dust, pollen, and other allergens, improving air quality and reducing allergy symptoms.

Microbial Control: Some activated carbon filters have anti-bacterial properties, preventing the spread of bacteria and mould.

Enhanced Comfort: Maintaining cleaner air provides a more comfortable and pleasant driving experience.

2. Acoustic panel

An acoustic panel is a sound-absorbing board designed to reduce noise, control echo, and improve the overall acoustics of an indoor space. 

Sound absorption panels for room acoustic applications generally comprise porous synthetic materials like rock wool, glass wool, polyurethane, or polyester. These are expensive to produce and are typically based on petrochemicals. The growing awareness of the environmental implications and health issues associated with these materials has increased the attention towards natural materials. Panels usually come from acoustic foam, recycled PET, fabric, wool, or other porous sound-absorbing substances. They work by absorbing sound waves, thereby reducing reverberation and echo, which enhances sound clarity and quality in environments such as offices, studios, and auditoriums.

Properties requirements:

Noise Reduction Coefficient (NRC): This is a measure of how much sound is absorbed by the panel. A higher NRC value indicates better sound absorption.

Sound Absorption Coefficient: This measures the panel’s ability to absorb sound at various frequencies.

Fire Resistance: Ensure the panels meet fire safety standards, particularly in commercial or public buildings.

In recent years, natural fibres have been considered valid raw materials for producing sound-absorbing panels at a reduced cost. kenaf, wood, hemp, coconut, cork, cane, cardboard, and sheep wool.  The sheep wool is an excellent sound-absorbing material, thanks to the micro-cavities of which it is composed. The absorption coefficient value resulted in high at medium and high frequencies.

The theoretical predictions obtained by applying the Delany Bazley model show values lower than those measured, especially at middle frequencies. For example, at 500 Hz, 1000 Hz, and 2000 Hz, the measured values were 0.66, 0.95, and 0.94, respectively, for the 6 cm thick sample.

Wool fibres naturally absorb sound, and the needle-punching process enhances this by creating a dense, porous structure that effectively traps and dissipates sound waves. Wool provides excellent thermal insulation, which can help maintain a comfortable indoor environment while contributing to soundproofing. (GSM  up to 1600 can be achieved.).

3. Warp-knitted Lycra Fabric

Warp-knitted Lycra fabric is a high-performance textile known for its exceptional elasticity, durability, and comfort. Created through a warp knitting process, this fabric combines the stretch properties of Lycra (spandex) with the stability of warp knitting, resulting in a material that offers excellent fit and freedom of movement. It is widely used in sportswear, activewear, lingerie, and medical textiles because it maintains shape and provides support. Additionally, warp-knitted Lycra fabric is breathable, quick-drying, and resistant to creasing, making it ideal for everyday wear and specialized applications. Recent technological advancements have further enhanced its properties, leading to innovative designs and sustainable production methods, ensuring its continued relevance and popularity in various industries.

Construction 

Typical operating parameters

Yarn Tension:

• Lycra Yarn: 2-5 cN (centi Newtons)

Gauge:

• Common Range: 18-28 needles per inch

Stitch Length:

• Elastic Fabrics: 2.5-3.5 mm

Relaxation Period:

• Standard: 24-48 hours at room temperature

Quality

Elasticity and Stretch: Warp-knitted Lycra fabric is renowned for its excellent elasticity and stretch, providing a comfortable fit and freedom of movement. This makes it ideal for activewear and sportswear.

Durability: The fabric is highly durable and resistant to wear and tear, making it suitable for garments that require frequent washing and use.

Breathability: It offers good air permeability, which enhances comfort by allowing moisture to escape, keeping the wearer cool and dry.

Crease Resistance: Warp-knitted Lycra fabric is crease-resistant, maintaining a neat appearance even after prolonged use.

Quick Drying: The fabric dries quickly, a significant advantage for sports and outdoor activities.

Applications

Sportswear and Activewear: Due to its stretch and comfort, warp-knit Lycra fabric is widely used in sportswear, including leggings, yoga pants, and swimwear.

Casual Wear: The fabric’s comfort and aesthetic appeal suit casual wear, such as t-shirts and dresses.

Medical Textiles: Its elasticity and durability make it ideal for medical applications, including compression garments and bandages.

Lingerie and Underwear: The fabric’s softness and stretch are perfect for lingerie and underwear, providing a snug yet comfortable fit.

Industrial Applications: Warp-knitted Lycra fabric is also used in industrial applications, such as automotive textiles and upholstery.

Current Scenarios

Innovation in Design: Recent advancements in warp knitting technology have led to the development of fabrics with enhanced moisture management and thermal regulation properties.

Sustainability: There is a growing focus on sustainable production methods, including using recycled materials and eco-friendly dyes.

Customization: Computer-aided design (CAD) and simulation tools like MATLAB have enabled more precise and efficient production of warp-knitted fabrics, allowing for greater customization and cleaner production processes.

Market Trends: The demand for warp-knitted Lycra fabric continues to grow, driven by the increasing popularity of athleisure and the need for high-performance textiles in various sectors.

About the Author: Ajay Kumar is a graduate of JNGEC Sundarnagar, Himachal Pradesh, where he earned his degree in Textile Engineering. He also holds a Master's degree in Textile Engineering and Management from NIT Jalandhar. With over four years of experience, Ajay specializes in the education of apparel, made-ups, and home furnishing sectors. He is currently conducting research at NIT Jalandhar, focusing on advancements in technical textiles.