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

Especially in technical applications, nonwovens come into contact with various fluids, chemicals including organic solvents and may also be exposed to sunlight or humidity. Sandler nonwovens are predominantly made of synthetic raw materials such as polyester or polypropylene and are resistant to most inorganic and organic substances. This resistance makes them durable and their specific properties are maintained throughout their operating life. By choosing a suitable Sandler nonwoven, discolouration, softening, bulging, detachment of coatings or blistering become things of the past.

In the automotive industry, this durability is tested according to VDA 621 by dripping selected test fluids on the material or moistening it with them. The temperature at which the test is performed may vary. Sandler nonwovens are tested according to VDA 621 by external institutes.

Specific applications require resistance against specific media or exposures:

Resistance to alkali

In construction, nonwovens come into contact with materials such as concrete or cement mortar. If the level of humidity increases, these building materials are prone to emit large quantities of alkaline salts. Sandler nonwovens are resistant to these alkalis: The nonwoven is unaffected, no disintegration occurs and fabric remains stable. These nonwovens are therefore highly suited to applications in construction. Their resistance to alkali is determined by subjecting them to different test media, usually over a period of several months. A subjective examination of the nonwoven’s structure is subsequently carried out and any decrease in weight and tear-resistance are measured. Sandler nonwovens are tested for resistance to alkali in our in-house laboratory.

Hydrophobicity & hydrophilicity

Hydrophobic nonwovens are water-repellent resulting in reduced fluid absorption. This characteristic is achieved without any additional finishes, using only specific polymers and the appropriate manufacturing technology. 

• Automotive: Hydrophobic nonwovens in exterior applications such as wheel house liners withstand any wind and weather. 
• Construction: Hydrophobic nonwovens dry quickly and thereby prevent an accumulation of moisture.  

In contrast, hydrophilic nonwovens easily attract water and transport it. Special product variants can also be applied for storing fluids. These nonwovens are highly suited to hygiene products or wipes.

Oleophobicity & oleophilicity

The term oleophobicity describes the characteristic of repelling oils and fats. These substances do not penetrate the material but simply run off its surface. Sandler nonwovens for the automotive industry are permanently resistant to engine fluids such as transmission fluid, engine oil or diesel and are  in-house tested for oleophobicity according to the drop test method. Likewise, Sandler nonwovens for filtration are resistant oils and fats.

Oleophilic nonwovens, on the other hand, easily absorb oils and fats and amongst others are especially in high demand for environmental applications.

Resistance to fungi, bacteria and moisture

Sandler nonwovens made of thermoplastic polymers are bacteriostatic, i.e. they prevent the proliferation of colony-forming units by denying any breeding grounds for fungi or bacteria. In humid conditions, this characteristic is particularly enhanced by their resistance to moisture: The fibres do not absorb moisture, therefore the nonwoven dries quickly.

• Filtration: Sandler nonwovens are tested for their resistance by external institutes. Corresponding certificates attest to the nonwovens’ suitability for application in ventilation and air-conditioning systems according to VDI 6022.
• Construction: This characteristic helps to prevent the growth of mould in buildings, protecting the health of the occupants.

Bacteriostatic properties are determined according to the DIN EN ISO 846 standard by evaluating the impact of micro organisms on synthetic materials. The nonwoven is placed on a culture medium to which different fungal spores and bacteria are applied. After a period of 4 weeks under defined temperature and lighting conditions, the growth of both fungi and bacteria is visually observed.

UV-resistance

In construction, for roofing and façades as well as in technical applications the utilised materials are frequently subjected to sunlight. Use of specifically chosen polymers result in Sandler nonwovens being UV-resistant: The material’s structure remains intact, neither discolouration nor disintegration being an issue.

UV-resistance is determined by means of an exposure test. Samples of the nonwoven may for example be placed behind window glass and subjected to real climate variations. Prior to and after the test, the nonwoven’s mechanical properties are determined, by checking for any detrimental effect from exposure to the UV-rays, in relation to the duration of exposure. 

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. 

Sound absorption describes the conversion of sound energy into heat. Materials featuring high sound absorption are excellently suited to sound insulation in construction or the automotive industry. Fibrous components such as nonwovens commend themselves to these applications owing to their porous structure. Fine fibres create a more or less flexible “fibre skeleton“, featuring a large inner surface. Sound is diffracted in numerous places, whereby sound waves are absorbed and dampened by the nonwoven. Their structure also makes nonwovens an ideal heat insulator.

Properties such as the material’s thickness, density, porousness and flow resistance determine the level of absorption. The measurement of sound absorption under random incidence is carried out in a reverberation room according to DIN EN ISO 354, or in a smaller alpha cabin. Sound absorption under vertical sound incidence can be determined according to DIN EN ISO 10534 in a Kundt's tube, or impedance tube. Sandler nonwovens are tested for their sound absorption properties in cooperation with external institutes.

Together with renowned partners from research and the automotive industry, Sandler developed a simulation tool, enabling the calculation of the required absorption level. New variants and products can be computer-simulated based on the required absorption profiles before the first trial production is undertaken. In this way, time and costs are saved and valuable resources conserved.

See also: Air-permeability

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. 

Retaining heat, preventing heat loss. Allmost everyone is familiar with these requirements when it comes to buildings, since we want to feel comfortable inside a building and be protected from wind and weather. However, whilst our cloths equally fulfil this function, efficient thermal insulation saves energy and costs. 

Nonwovens are characterised by a special open-pored structure, featuring a porosity of up to 95 percent. The structure comprises very fine fibres and a large inner surface which also contains air—a very efficient heat insulator—setting the stage for excellent thermal insulation. The density and fibre structure of a nonwoven influence its thermal conductivity. By tailoring basis weight, thickness and fibre blend, the required level of thermal insulation can be achieved, thus having the ability to create a specific nonwoven for every application.

• Automotive: In the automobile, nonwovens also function as heat insulators. For instance they contribute to reducing fuel consumptionwhen used to retain heat in the engine compartment.
• Construction: Used as insulation materials for interior and exterior applications in roof and walls nonwovens add to a feel-good atmosphere, lowering the energy input by efficiently retaining heat, thus reducing costs.
• Outdoor clothing: Nonwovens retain body heat to maintain warmth.

In determining thermal insulation properties, the nonwoven’s thermal conductivity is vital. It is stated in the lambda coefficient of thermal conductivity: The lower the value of lambda, the higher the thermal insulation. Thermal conductivity is measured according to ISO 8301 or DIN EN 12667 using the heat flow method with plates. The test is carried out at an average sample temperature of 10°C. 

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.

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.