PROCESSING AIDS & PROTECTIVE NONWOVENS

Breathability describes a fabric‘s ability to allow air and water-vapour to permeate, preventing the accumulation of moisture. Breathable materials thus increase comfort in use and avert skin irritation, particularly in applications involving direct skin contact. 

• Hygiene products & wound dressings: Breathable nonwovens allow the skin to breathe, increasing wear comfort whilst preventing an accumulation of fluids and skin irritation, particularly during extended use.
• Automotive: Breathable textiles in the car seat increase driving comfort, especially on long journeys. 
• Construction industry: Permeable nonwovens contribute to the health of the occupants. They allow the walls of buildings to breathe when required. Simultaneously, they avert the accumulation of moisture, thus preventing structural damage and potential health issues caused by mould formation.
• Mattresses & bedding: Breathable materials allow for a restful and comfortable sleep.
• Fashion: Breathability is a vital function for product performance. 

Breathability, also referred to as resistance to water vapour permeability, can be measured according to DIN EN 31092, respectively ISO 11092 using the thermo-regulatory model of human skin. Breathability indicates the rate at which perspiration is transported through the material. 

Extensible nonwovens facilitate contouring of the material to the respective application: 

• Hygiene products: In diaper ears and other stretch applications, elastic nonwovens enhance this characterisation. They flexibly adapt to the wearer’s body, adjusting to any movement and optimising comfort in use. Extensible under a low load, with excellent recovery properties.
• Automotive, technical applications & home textiles: Malleability is a key requisite when nonwovens have to follow a contour. These nonwovens facilitate processing and dependably insulate or protect complex components. 
• Construction: Used in repairs to a façade for example, elastic nonwovens are applied in crack bridging. They adapt to expansion or shrinkage of building materials and are capable of recovering their original dimensions, offering a long-term solution to construction defects.

Extensibility is measured by determining the maximum tensile force and the maximum elongation according to WSP 110.4 in machine direction and cross machine direction. Sandler performs these tests in our in-house laboratory.
Elastic properties are determined by employing the so-called hysteresis test following DIN 53835. During these tests, the material is repeatedly stretched up to a defined maximum tensile force. The maximum elongation achieved at the predefined force as well as the material’s permanent set are measured. The ideal permanent set value is required to be as low as possible, signifying that the material does not wear out during use. These tests are also performed in Sandler’s in-house laboratory.

Health is our greatest asset; protecting it is Sandler’s philosophy. Using specific combinations of raw materials and manufacturing technologies, Sandler nonwovens actively contribute to furthering this objective. They may be made of polyester from recycled drinking bottles and even the single-polymer nonwovens used in our clothing styles are fully recyclable. Sandler does not employ any chemical additives in the manufacture of these materials and furthermore, they are odourless. These nonwovens therefore protect the health of converters and end-users alike. 

In processing and using synthetic materials, various emissions may occur. Some examples of these are:

• total carbon emissions; measured according to the VDA 277 standard 
• odours; for which the material is tested according to VDA 270-C3 
• formaldehyde emissions; measured according to VDA 275. This substance may cause headaches, mucosal irritation or respiratory problems and can even trigger asthma or allergies upon long-term exposure.
• fogging—condensation on windows in vehicles generated by the aforementioned emissions; measured according to DIN 75201

Materials for a defined product are specially chosen to avoid these emissions, resulting in Sandler nonwovens falling below the accepted limits in all of these categories. 

• Hygiene & wipes industry: These products are intended to protect the well-being of the user, while remaining virtually unobserved. Only high-quality base materials are selected to which rigorous criteria are applied in order to ensure a low level of emissions. Sandler applies no chemical additives to avoid the generation of unpleasant odours.
• Automotive industry: Sandler nonwovens do not release unpleasant or harmful emissions—designed for comfortable handling and long-term enjoyment. 
• Filter media: In ventilation and air-conditioning systems Sandler nonwovens allow us to breathe freely without having odours and other emissions impairing the air quality.
• Insulation materials for construction: In buildings, low-emission Sandler nonwovens are an excellent alternative for people suffering from allergies, contributing to the preservation of the occupants' health. 
• Acoustics in offices & home textiles: Sandler nonwovens are odourless and virtually free from formaldehyde*, rendering both workplace and our homes as real comfort zones.

In cooperation with our partners, Sandler also offers an anti-odour finish that eliminates odours, for example for nonwovens applied in vacuum cleaner bags.  

* below the detection limit

Mechanical stability is a vital property in nonwovens. It describes their resistance to tearing or breaking caused by mechanical influences. In many applications, nonwovens are subject to strains such as vibrations during processing and use or to compression. Mechanically stable nonwovens withstand these forces, being tear-resistant and having low elongation values in machine and cross machine directions. 

• Wipes: Variants featuring reduced elongation for household and industrial cleaning support even heavy-duty applications.
• Filtration: Mechanically stable nonwovens resist the volume flow in use as well as vibration in the filtration plant. 
• Technical applications: Mechanically stable nonwovens are used for sheathing and other reinforcements. 

To determine a material’s mechanical stability, maximum tensile force and maximum elongation in machine and cross-machine directions are measured at varying parameters according to WSP 110.4. Mechanical stability also embraces several properties specific to the respective application:

Abrasion resistance

In car seats, in furniture, in technical applications and even in cleaning wipes nonwovens are subject to abrasion, which may weaken the nonwoven’s structure. Since the nonwoven is made up of single fibres, these fibres have to be well anchored in the fibre matrix to provide appropriate cross-directional stability. In this way, abrasion resistance is achieved. In the production of nonwovens, Sandler relies on fibres with a high resistance to breakage, thereby fulfilling these requirements.

The abrasion resistance of a nonwoven can be determined using the so-called Martindale test method or according to the DIN EN 530 standard. The materials are classified in requirement categories, depending on the number of scrub cycles as determined by testing. The more cycles endured by the nonwoven, the higher its abrasion resistance. This test can be carried out by our external partners if required. 

No fibre shedding and minimised fibre breaking

Sandler nonwovens are made of synthetic fibres that do not shed and due to their elasticity and resistance to breakage, result in the minimum of fibre debris. These media do not cause skin irritation and present no health risks—for example in the automotive industry or in construction. Sandler nonwovens thus meet the requirements of product class 1 of the Oeko-Tex^® standard 100, bearing the “Confidence in Textiles” label.

In filtration, this characteristic is of paramount importance: If the fibres are brittle, fibre fragments may become detached and contaminate the source of the clean air stream. 

Bending stiffness

Materials featuring high resistance to bending demonstrate high stability even under strain. This property is particularly relevant for use in self-supporting structures intended to be installed overhead using only few fastening points. Vibrations may develop in use, transposing the component’s weight into a strain. Stiff materials do not deform under load and do not sag. They retain their residual stiffness over the long term. 

• Automotive: Nonwovens featuring high bending stiffness are in demand for moulded parts such as headliners. 
• Construction industry: Stiff nonwovens are applied for acoustic ceiling panels and other ceiling structures. 

At Sandler, bending stiffness is determined using the three-point-method according to DIN EN ISO 14125: A sample is deformed at a constant rate; the applied force and the deflection are measured. This test is performed in our own laboratory. 

Tread-proof

In roof construction, the raw materials are literally being walked on. Sandler nonwovens for insulation laid on the rafters or bituminous strips feature a pressure- and tread-proof upper side for safety in roof work. Even under pressure they remain firm, due to their high bending stiffness.

Hydrophilic nonwovens easily absorb water and transport it on. Use of special product variants enables storage of the fluid. Oleophobic nonwovens are capable of absorbing high levels of oils and fats.

• Hygiene products: In these applications, nonwovens are required to quickly transport the maximum amount of fluid to the absorbent core for storage and prevent rewet.
• Wipes: The lotion applied to the nonwoven is absorbed but allows a sufficient amount to be released again during application.
• Automotive: Nonwovens used in the seat are required to quickly and reliably absorb water vapour, creating a continually pleasant micro-climate in the seat.  
• Environmental applications: In this area of use, highly absorbent nonwovens are applied to assimilate oils, water or other fluids. 

Hydrophilic properties are tested according to WSP 10.1. For example, capillary rise is determined by the speed of fluid absorption and its distribution. The wider the distribution throughout the material, the better the storage capacity. this property for instance, is exploited in the absorbent core of a hygiene product. Another test focuses on maximum fluid intake, determining the level of fluid the medium can store.    

See also: Resistance

The fibrous structure of nonwovens combined with diverse bonding technologies creates a multitude of different structures and surfaces, optimising and complementing function and efficiency of these materials depending on their respective application:

Plain surface

No plain surface is like the other. Depending on the requirements of the application, numerous “plain“ surfaces variants are available. A smooth / plain surface also characterises optimised surface integrity.

• Wipes: Smoothing the surface reduces linting. Furthermore, the nonwoven gains a more compact feel and becomes more stable due to a reduction in elongation.
• Automotive industry: Surface smoothing lends stability to the material and improves processability.
• Fashion: A well-bonded surface prevents fibres from penetrating the outer fabric.

Perforation

Perforating or aperturing offers a specific method of surface structuring. It changes the material’s surface, giving the nonwoven a special design as well as additional functional properties. In wipes substrates perforation improves the cleaning effect: It enlarges the material’s surface area, enhancing its dust hold capacity.

Embossing

Embossed nonwovens combine design and function. The material can be embossed with various motifs as a visual eyecatcher. In many cases, however, these designs also enlarge the nonwoven’s surface—a definite “plus” when it comes to dirt collection in wipes or absorbency in hygiene products. Multi-layer structures may be bonded via an embossing process, attaining adhesion between the layers without binders. Depending on the material and the utilised polymers these structures can be created thermally or by using hydro embossing. Visit our Design section for more details.

In offices or public spaces embossed acoustic components made of nonwovens may also offer a design feature.

Printing

Many Sandler qualities are available with end use oriented print motifs. Various designs for the hygiene and wipes industry emphasise the respective application. Visit our Design section and see for yourself or contact Sandler for your customised print design.

In technical applications such as filtration or construction, performance parameters such as the filter grade, relevant testing standards or the classification pertaining to thermal conductivity can be printed onto the material using inkjet printing upon special request of the customer.

Multi-layered structure

Nonwovens can also be used in the form of composites consisting of several layers. Different nonwovens are combined with one another or with other materials. These multi-layered structures combine the diverse properties and functionalities into one product, fulfilling the highest quality standards. Multi-layer composites may also facilitate processing. The possible combinations are virtually unlimited:

• Hygiene industry: Multi-layer nonwovens combine several functions in one product, such as the transport and storage of fluids. 
• Medical applications: Together with other materials nonwovens also function as padding for improved in use comfort, particularly in extended use.
• Wipes: In cosmetics and other applications the combination of fine and coarse layers improves the cleaning effect. 
• Automotive & upholstered furniture: Multi-layer nonwovens facilitate processing and lend stability, for example to leather seats: when laminated onto the leather, they prevent overextension in use, thereby reducing unsightly creases in the seat.
• Filtration: Multi-layer composites lend stability to the products: Ceiling filters, for example, are rendered more stable by a polyester fabric laminated to the medium.
• Technical applications: Composites of nonwovens or with a multitude of other materials can increase the stability or even the resistance to heat, acids or other influences.
• Fashion: Lamination to nonwovens imparts optimum surface integrity and prevents pilling and fibre penetration.

In furniture, in hygiene products, in the automobile, in outdoor jackets and as industrial cushion liners for packaging, these nonwovens facilitate processing, contribute to the end-product’s durability and protect surfaces. The following properties are relevant to this characteristic:

Recovery rate

The recovery rate describes a material’s ability to relax or regain its original shape after long-term, constant strain.

• Hygiene industry: In this sector, elasticity and stretch are important for nonwovens used in diaper ears and other closures.
• Automotive: A high recovery rate in nonwovens used in seats provides for long-term driving comfort. These nonwovens yield to deformation, yet remain stable.
• Upholstered furniture: Nonwovens featuring a high recovery rate render furniture durable and contribute to a high level of long-term comfort.
• Mattresses: The formation of dents and creases can be prevented, resulting in permanently comfortable sleep.

In technical applications, the parameters for testing this property are stated in DIN 53517 or DIN ISO 815. The so-called compression set value as measured is expressed as a percent. A sample is compressed by a defined value and held in this state for a given time at a defined temperature, the specific test parameters being dependent on the intended application. 30 minutes after relaxation the material’s thickness and plastic deformation are determined. For hygiene products, the material’s elastic properties are measured by means of the hysteresis test following the procedure in DIN 53835.

Volume

Voluminous nonwovens are particularly bulky for improved visual effect, processability and performance:

• In furniture these nonwovens create unrestricting bulky upholstery, particularly for soft upholstery in the backrest—perfectly suited to the latest design trends.
• Mattress covers are even more comfortable with voluminous nonwovens.
• In outdoor clothing voluminous materials provide for a higher level of heat retention.

At every stage of the manufacturing process, Sandler relies on sensible raw material usage in order to conserve natural resources. A major focus is thus placed on both preventing and reutilising production waste. Whenever the requirements of the production process will allow, accruing by-products are reprocessed by feeding into production as raw materials. If this internal utilisation is not possible, these surplus raw materials are recycled externally. In this way, both raw materials and nonwovens are part of a closed raw material cycle, conserving valuable resources. 

Manufactured without any additives, our single-polymer nonwovens support this recycling philosophy. Sandler polyester nonwovens e.g. in construction applications or in the automotive industry can be recycled after use and reprocessed into new raw materials without having to employ elaborate separation processes. With product specification compliance, recycled polyester fibres are increasingly used—familiar to most every consumer from the recycling of PET bottles.  

In selecting raw materials for wipes substrates sustainability is also of major importance. Rayon fibres of European origin derived from controlled forestry and certified according to PEFC™ oder FSC^®  standards are utilised. The product range also offers biodegradable product variants, made from 100 % rayon fibres.

An energy management system installed directly on our production lines optimises energy consumption and reduces CO₂ emissions: energy monitors show the actual consumption during production. Our experienced staff can adjust the settings to minimise energy usage without influencing the properties of the finished product. Use of heat recovery systems further reduces energy consumption. For several years, an energy task force has been monitoring energy consumption throughout the company, identifying potential reductions and proposing measures for implementation.

In their respective applications nonwovens contribute to conserving valuable resources: Durable materials prolong replacement intervals of filters and other products, reducing raw material requirements for replacement products. In the automobile nonwovens also function as heat insulators in the engine compartment, preventing loss of temperature. Thereby, cold starts are reduced; fuel consumption and emissions are lowered and resources are conserved. For this market Sandler developed simulation software in cooperation with partners from the industry. It allows the required product properties to be computer-simulated, foregoing resource-intensive trial productions. 

Flame-resistant products meet particular demands in the event of fire. Subjected to blaze, sparks or open fire, they do not catch fire immediately. When ignited, these structures do not continue to burn, but extinguish after a specific time.

Depending on the specific application and national regulations, various test standards apply:

• Automotive applications: DIN 75200, MV SS 302, PV 3357 and UL 94
• Filtration: The provisions regarding flame-resistance are laid down in DIN 53438 standard.
• Construction: Nonwovens for office fittings and mattresses used on ships and trains are evaluated according to DIN 4102 or DIN EN 13501 standards.
• Upholstered furniture: BS 5852 standard is decisive in this sector.

Our nonwovens are tested for flame-resistance in cooperation with external testing institutes.

In various applications nonwovens are subjected to permanently high temperatures and/or occasional temperature spikes. The utilisation of specific polymers enables Sandler nonwovens to withstand these conditions. Produced without chemical binders, these materials do not emit vapour under the influence of temperature and remain durable and dependable even in demanding applications.

• Engine compartment: In these applications, nonwovens are resistant to “under the hood” fluids as well as the prevailing temperatures.
• Filtration: In applications such as heat exchange systems filtration nonwovens resist the prevailing temperatures.
• Pipe insulation: In heating and systems engineering as well as in solar systems temperature-stable nonwovens are used.  

Sandler tests its nonwovens for temperature-stability in-house. The materials are stored in a compartment dryer for a specified amount of time and any changes to the nonwoven are subsequently reviewed. Climate tests and other analyses documented by test certificates are carried out by external testing institutes. 

Finishes

Sandler nonwovens can be offered with different finishes to supplement functionality: for example with lotions, cleaning agents, an antibacterial finish or a flame-retardant finish to increase flame-resistance.

Printing

Nonwovens can be printed all-over or with detailed motifs using thermal transfer printing, digital printing, flexo printing or other established printing technologies. 

• Hygiene & wipes industry: Print motifs emphasise the application and offer visual differentiation. 
• Office design: Acoustic components for interior decoration can be printed to offer a design facet. Thermal transfer printing increases surface bonding and smoothes the nonwoven’s surface.

With the intention of improving the print result, the surface of Sandler nonwovens may also be pre-treated by roughening the fibres.

Adhesive coating

Adhesive coating can be applied on one or both sides of the nonwoven. In filtration for example, ceiling filter media are coated with an adhesive finish to facilitate processing in the end application. The coated parts are protected by a release film. Once this film is removed, the nonwoven can be used as intended. Pleatable filter media can be equipped with spacers made of hotmelt adhesive.

The nonwoven can also be pre-treated to enlarge the fibres’ surface to improve bonding with the adhesive.

Pleating 

Sandler's pleatable nonwovens for the filtration industry are suitable for processing on knife as well as rotation pleating lines. A homogenous, longitudinally oriented fibre structure provides for particularly accurate pleating and high pleat depths. The polymers utilised are temperature-stable, elastic and resistant to breakage, thus offering high stability: The pleats are dimensionally stable, yet are also flexible. They withstand mechanical influences during processing and temperature and humidity during use.

Cutting & die-cutting

Sandler nonwovens are easy-to-process using established cutting technologies such as band knives, CNC cutters, straight knives, water-jet cutting or laser cutting. Perforation cuts for tearoff wipes, for example, are also possible.

For hygiene products, automotive industry products, and for mat filters die-cutting is used, to which Sandler nonwovens are highly suited. Particularly in automobiles precision contouring facilitates accurate assembly onto the particular component. The material is also not distorted during die-cutting, resulting in accurate cuts with clean edges.

Sewing

By selecting appropriate fibres, Sandler nonwovens are easily processable and can be sewn without difficulty—in the manufacture of fashion, mattress covers, car seats, and for pipe insulation or the production of pocket filters.

Embossing

To achieve adhesion between layers, as an eye catcher or for the selective deformation of voluminous materials: Sandler nonwovens are embossed for a variety of applications. They are well suited to both calender and ultrasonic embossing, frequently used for the hygiene industry. In the automotive sector, embossed nonwovens are also used for example in engine cover parts. Again Sandler nonwovens are ideally suited to the processes employed in this industry, such as hot and ultrasonic embossing.

Moulding

Due to the thermoplastic properties of the selected polymers utilised Sandler nonwovens are mouldable and are able to match the contours of the component. In addition, the material can also be hardened through moulding.

• Automotive industry: Nonwovens are for example processed into 3D moulded parts such as headliners or wheel house liners.
• Interior design: Acoustically efficient moulded parts made of nonwovens are also making advances into interior design. One recent example: a designer lamp shade. 

In the filtration industry nonwovens are generally pre-heated prior to pleating. Sandler nonwovens are well suited to this process.

Welding

The polymers used make Sandler nonwovens totally compatible with ultrasonic welding, high-frequency welding or thermal welding techniques.  

• Automotive industry: Ultrasonic or high-frequency welding spots are used to fasten nonwovens to die-cut or cover parts.
• Filtration & hygiene industry: Multi-layer composites can be bonded using ultrasonic or high-frequency welding.
• Technical applications: Nonwovens for pipe insulation are sealed using common welding technologies.

Laminating

Depending on the specific application, Sandler nonwovens can be laminated with different materials to produce multi-layer structures with multifunctional properties: for improved acoustic efficiency, hardening, greater stability, resistance to heat or for improving mechanical properties. In fashion, the nonwoven is bonded to the outer fabric, in hygiene products multi-layer structures combine reliable protection with comfort in use—the possibilities are virtually endless.

In the hygiene industry, nonwovens are frequently transported to the laminating line on a vacuum conveyor belt. This process poses specific demands on the material’s air-permeability and Sandler nonwovens provide these characteristics.