ENVIRONMENTAL APPLICATIONS

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.

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. 

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

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.