Filling fibers are used in bedding, clothing, upholstery materials and some special materials. Depending on the place of use, the properties expected from good filling fibers are not always the same. Physiological properties of filler fibers that provide sleep or wearing comfort are heat insulation and air and moisture permeability. In recent years, in addition to heat insulation, moisture transfer and moisture management have gained importance, filling fibers have gained importance in the market of mattresses and quilts.
Other properties expected from filler fibers are fullness, bulkiness, elasticity, softness and compressibility. The degree of importance of these features varies greatly depending on the product type. In addition, these features should be resistant to use, dry cleaning or washing and should be able to recover after use. Although natural materials were used as filling fibers in the past, today the use of synthetic fibers, especially polyester fibers, has increased.
Features such as increased production of polyester fibers, falling prices, lack of felting tendency, resistance to moths and other insects, and not holding dust provide advantages in using them as filling fibers.
Filler fibers are fibers that provide low weight, high thermal insulation, moderate air permeability and good bulk elasticity, providing voluminous nonwoven surfaces. Filler fibers, such as mattress, quilt, pillow and sleeping bag fillers, anorak, padded top coat, dressing gowns, sportswear, layered cheesecloth pads for sailor and aviator clothing, fixed upholstery, bottom and back cushions, vehicle upholstery and dust, air filters insulation pads. It is used in some special materials.
In the past, natural materials such as wool, kapok, straw, animal skin and hair and bird feather were used as filling materials, but nowadays the use of synthetic fibers as filling material has gained increasing importance. Polyester fibers are the most used synthetic fiber, which provides the best results as a filler fiber. Price has always played a prominent role in the use of these materials. However, there has been an increase in the use of PES as a filling fiber due to its increasing commercial production and falling prices.
2–6% of the volume of a good lap obtained from filling fibers is composed of fibers and 94–98% of the reclaimed lap is air. The specific gravity of polyester fibers (1.36–1.41 g/cm3) is higher than other synthetic fibers. The volume of the wadding obtained with PES fibers is 3 times more than other fibers.
Fiber properties that affect the performance of the filling product
The properties expected from filler fibers, which have many different areas of use, may vary. Physiological properties of filler fibers that provide sleep or wearing comfort are heat insulation and air and moisture permeability. The heat conduction number of all normal fibers is about 10 times higher than the heat conduction number of air. The thermal insulation ability of a wadding consisting of filling fibers does not depend much on the thermal conductivity of the material from which the fiber is made, but on the amount of air in the wadding and the shape of the air spaces.
In other words, the lower the fiber content in the lap and the higher the amount of air, the more the thermal insulation of the lap increases, approaching the insulation value of the air. However, if the gaps between the fibers are too large, the heat insulation effect may be reduced due to the increased air movement inside the wadding. On the other hand, it is necessary for the wadding to have a certain air permeability as it also provides moisture permeability.
The diffusion constant (10.10–4 cm2/s), which determines the movement of moisture in the fibers, is very low. However, the diffusion constant, which determines the transport of water vapor by air, is 25.10–2 cm2/s. In other words, it is 250 times larger than what is inside the fiber.
Therefore, moisture (sweat) transport in materials that do not come into direct contact with the body, such as filler fibers, does not play any role depending on whether the fibers are hydrophilic or hydrophobic. Because most of the sweat is carried by the air in the pores between the fibers, synthetic fibers provide good results in this regard due to their hydrophobic surfaces. In summary, when the size and amount of the pores between the fibers are chosen correctly, it turns out that pads made of synthetic fibers can provide both a good thermal insulation and a good sweat transfer. Other properties expected from filler fibers are issues such as fullness, bulkiness, elasticity, softness and compressibility, and the importance of these properties varies greatly depending on the product type.
In addition, these features should be resistant to use, dry cleaning or washing and should be able to recover after use. Hydrophobic polyester filling fibers are more hygienic than natural fibers, as bacteria love hot and humid environments. The surface structure of the fibers and the absence of large pores in the fibers also make it difficult for all kinds of microbes and bacteria to settle and reproduce in these fibers. In addition, properties such as the lack of felting tendency of polyester fibers, resistance against moths and other insects, and non-dusting are also advantageous in their use as filling fibers.
Polyester fibers are non-allergenic and their low moisture recovery properties make them less sensitive in wet or humid conditions. Less energy is required for the drying of PES fiber after washing. Such properties are also found in other synthetic fibers such as polypropylene.
Bird feather, a natural material, is a good insulator.. The space created by the bird feathers traps the air and creates a "dead air space". This keeps the body warm. Bird down provides the best insulation compared to other fibers when compared to its weight. The down is flexible, absorbing moisture and helping to move it out of the body to evaporate. It takes shape according to the wearer's body and is easy to clean.
In addition to these, there are various disadvantages of using bird feathers. Feather is expensive, can easily hold dust, and can cause allergic reactions in some people. In addition, bird feathers can be easily dragged in the air. It must be covered with a lint-proof lining and placed properly in the garment before being sewn to ensure adequate insulation. When clothes containing down as a filling material get wet, down can retain only 10% of its insulating ability and takes a long time to dry. Mold can occur when the product does not dry well enough.
However, when the down clothing is folded, compressed and stored for a long time, the air it contains is lost and the insulation capacity can be reduced. Goose down filling material contains at least 70% feather, 10% fiber and 20% residue. There are two main sources of goose down in the world, China and Europe. The essentially expected property in filler fiber products is the filling power or the amount of fiber required to fill a certain volume. The height under low loads is defined as the initial volume. Fiber properties that affect initial volume are flexural modulus, crimp type/degree, fiber-fiber friction, and fiber content per unit area. The supporting volume is the final density received under a certain load. The supporting volume is also controlled by the same factors, but the desired values are different. The vertical volume can be increased by high amplitude, low frequency mechanical crimp and partially high denier.
The supporting volume can be obtained by low amplitude, high frequency mechanical or spiral folding. The fiber flexural modulus is proportional to the fourth power of the denier and therefore the denier is considered to have a very significant effect on volume. However, 4-15 denier fibers are conventionally used in the production of filler fiber and the effect is lower than expected. This is because high denier products contain less fiber per unit weight and lower overall fiber-to-fiber friction. This type of fiber is also difficult to curl. This process is done by heat crystallization in polyester fibers.
Softness depends on the difference between the initial and supporting volume and, in some cases, the stress-strain curve. The spring feature is the ability to recover after compression. This is a function of the elastic modulus and resistance to the stored energy required for fiber friction. Spring is a function of the elastic modulus. Straight fibers show less springiness than others.
Usage Areas of Filling Fibers
The properties of polyester filling fibers are very suitable for use in pillows and they have become the most important fiber in this market. Recycled polyester and polyester production residues are also used in pillows due to its low price and widespread availability in the market. Enough filling fiber for a sleeping bag can be obtained from 35 2 liter PET bottles.
What is expected from pillows is primarily volume, softness, springiness, reswelling and washability. The hollow fibers give the pillow a higher flexural modulus, increasing its volume and reducing its weight. Low friction, smooth silicone fibers increase softness and reswellability. In the bedding group, which consists of products such as quilts, bedspreads, mattresses and mattresses, each product includes different performance criteria. Quilts should be light, soft, fluffy, and warm.
Fibers are prevented from coming out with special fabrics. Today, mattress manufacturers use different, expensive fabric types, constructions, and different and creative fiber blends to add new qualities and benefits to their products. Even fabrics made from Tencel and Seacell are used in pillows and bedding. Silver-infused filler fibers are also used as filler fiber. In addition, bio-active fibers can be used in mattress and pillow fillings. Bio-active fibers are textile fibers that generally show activity against micro-organisms.
Furniture and filters are the largest market for filler fiber.
For this purpose, cheap and non-branded PES products are generally used. PES filling fiber is used in large amounts in the arms and back parts of upholstery furniture. The fibers used are heavy fibers such as 15 denier, but light fibers such as 6 denier are also used. Fibers used in seat cushions are expected to maintain high supporting volume, good springiness and form. Hollow fibers with excellent insulating properties are widely used in mattresses and sleeping bags.
Other types of filling fibers have rapidly started to replace foams in furniture due to fire and health problems. In furniture, instead of springs, elasticized narrow woven tapes and dangerous foams that emit toxic gases, flame-retardant filling and lining fabrics are used. Highly flammable fibers and fabrics are increasingly used in the entire home textile industry.
In filling fiber applications other than pillows and quilts, the fibers are stabilized for easier use and to prevent them from coming out of the furniture or product. In the past, aqueous emulsions of polyvinylacetate, vinylacetate, acrylics and polyvinylchloride, latex resins were used for this purpose. However, since these systems cause air and water pollution, they have been replaced by binders in many products. Since amorphous monocomponent binder fibers cause too much shrinkage, bicomponent binder fibers coated with low-melting amorphous polyester on PET are generally used.
Round and trilobal fibers are used in filters and high dirt holding capacity is expected from the fibers. More yield is obtained from fibers of lower denier. The sleeping bag market is divided into two parts as conventional and high-tech products. Filling capacity, volume and price are the determining factors in conventional products.
In advanced technology products, there are requirements such as low weight, high volume, low sensitivity to wet conditions. High volume, hollow, smooth fibers are used in staple or tow form. Many overalls are made from two types of filling materials, goose or duck down and synthetic filling materials.
POLIESTER FILLING FIBERS
The development process of PES filler fibers is listed as follows:
1955 Filling fiber designed for the first time
1968 First silicon fiber
1971 First hollow fiber
1982 First 4-hole hollow fiber
1987 Market entry of patented fabrics
1989 First 7-hole hollow fiber
1994 Introduction of 3 denier hollow fiber
1997 Introducing germ-proof fibers in Europe for the first time Introducing helical-crimped fibers in Europe for the first time
1998 Introduction of the dual brand project with Teflon
2000 Enhanced hollow helical-crimped fibers
2001 Launch of dust-repellent mite fibers
2003 Introducing the molded, anti-snoring ergonomic pillow
2004 Launch of modified polyester fiber that provides washing at 95°C
2005 Introducing bedding materials that balance their own temperature according to the sleeping temperature for a better sleep quality
In 1955, Du Pont company started to produce special fiber to be used especially as filling fiber.
These fibers are 4,75 denier, 8-10 crimp/inch, staple and controlled serrated, crimped fibers. These staple fibers, which are sold as filling fibers, have replaced cotton, feather and foam in pillows, sleeping bags over time. Products made from these new fibers are high-volume, lightweight, washable and non-allergenic. Three years after this first special fiber production, Du Pont company produced Dacron 3, 4,25 denier, spirally crimped, better volumizing and protecting fiber. In 88, the fiber named Dacron 1962 took its place in the market especially for use in pillows. Using these fibers, soft, medium and hard pillows have been developed with a combination of spiral and mechanical crimping.
In 1962, a new 56 denier fiber named T-15 was produced to replace cattle, pig and horse hair in furniture and bedding. Companies such as Rohm and Haas, National Starch and Goodrich have introduced latex binder emulsions to be used for filling purposes. These fibers were then used by waterbed manufacturers to prevent wave formation.
The production of filler fibers increased in the 60s. The American Eastman company produced Kodel fiber based on 1,4 cyclohexanediol and terephthalic acid. When Whinfield and Dickson's patents expired, Eastman replaced their product with inexpensive polyethylene terephthalate. Later, they introduced the super white Kodel 142 product for dresses and bras. The ICI firm, which produces filling fiber in England, and the American Fortrel firm cooperated.
The development of synthetic filling fibers has been slow due to the preference of natural filling fibers in Europe. The prices of filler fibers, which were sold at the price of cheap cotton blends in the early 60's, have increased due to the specialty fibers developed since the early 70's. The low-friction fiber with a permanent silicone finish developed by Dupont made the pillows feather-like but more compressible. The hollow filling fiber named T-808 also increased the volume by about 15%.
In the 70s and 80s, product modifications increased rapidly. Increasing energy prices due to the oil crisis has led to the replacement of polyester fibers by glass fiber in the insulation market. Du Pont and Eastman have introduced monocomponent binder fibers based on low melting polyester copolymers.
Compared to latex resins, they have many advantages such as less energy is required during production, more elasticity can be provided and environmental problems of the resin can be eliminated since the drying step is skipped. However, the amorphous structures of binders with low melting points cause high shrinkage. Later, these binder fibers were replaced by core/core binder fibers. 3M has also produced Thinsulate R fiber, based on a polyester reinforced with a fast-tensile polyolefin. In the mid-'80s, Albany International produced super-insulating fibers based on polyester micro-denier fibers.
Du Pont company also produced Thermolite filler fibers containing low denier polyester fibers and 7-space fiber called Quallofil instead of the single channel filler fiber used by other companies. A hollow conjugated fiber was also produced by Unitika and Sam Yang. This fiber consists of a combination of space and spiral crimp and provides volume. It is primarily used in furniture and toys. An antimicrobial filler fiber named Stafresh was also produced by Du Pont. This product has increased the odor and mold resistance of the filling fibers.
At the end of the 80's, new forms of filling fibers emerged. Instead of combed fibers, small slippery tangled piles about 1/8" in diameter were used in pillows and furniture. Since these mixed clumps can easily pass through each other, these products can easily swell again and are more aesthetic than down feathers. The fiber offered to the market by Du Pont in this context is Comfortel, and Unitika company has introduced these fibers to the market under the name Optima in the USA. Generally, filling fibers are sold as staples. Exceptions are the products of the company Hoechst/Celanase. It is possible to examine polyester fibers, which have the highest usage rate as filling fiber, in three groups.
Normal Polyester Filler fibers
The fullness, softness, bulkiness, elasticity, compressibility and even indirectly (because it affects the air spaces between the fibers in the wadding) physiological properties of the filler fibers are primarily related to the fineness, length, cross-section and crimp shapes of the fibers, as well as their chemical structures. Generally, polyester filling fibers are preferred to be 5-7 dtex, and even those used in upholstery 12-17 dtex. Thinner fibers are undesirable because they do not provide the desired strength, and thicker fibers are undesirable as they show bristle character.
The optimal fiber length is between 30-50 mm. Shorter fibers are not preferred because the volume is insufficient, and if they are longer, the risk of the fibers getting stuck together and forming agglomerates increases. It is also important that the fibers have a good crimp. In fact, the use of three-dimensional, spiral-shaped fibers instead of two-dimensional folds provides good results in terms of bulkiness.
Filler fibers do not need to have high tensile strengths or initial modulus. For this reason, the low quality polyester melt obtained during the reuse of polyester residues in recent years can easily be used in filling fiber spinning.
Channel Polyester Filler Fibers
Channeled fibers such as Quallofil, Fidion, Diolen 620 and 623, Loftguar, Superloft, Hollow Fiber, Trevira 806…. It provides a lower weight and a softer handle. These fibers are obtained by using nozzles with special holes. For example, Quallofil fibers produced by Du Pont contain four channels parallel to the fiber axes. The fineness of the channel fibers generally varies between 4,4-6,7 dtex and their length is around 50-75 mm.
Channeled filling fibers are also used in the form of wadding, which is prepared by putting several layers of cheesecloth on top of each other, after being turned into cheesecloth on the cards. It is generally not practiced to fix the padding lap by means of a binder. Therefore, the wadding obtained from them is softer. In many cases, by applying silicone preparations that give a slippery feature to the surfaces of the fibers, the fiber/fiber retention is reduced, thus making the padding pad softer thanks to the fibers that can easily slide over each other.
polyester filler cables
Staple fibers are used in both filling wadding types mentioned above. In other words, during fiber production, the fiber cables in which the fiber strands are in parallel are first cut and the obtained mixed staple fibers are then opened with combs and parallelized to obtain cheesecloths. Fiber cables in which the fiber wires are in parallel are also used without cutting. The fiber cable cheesecloths obtained in this way, after being folded on top of each other to the desired thickness, are stitched together with a top and bottom fabric by a multi-needle sewing machine and gain a stable structure.
In the next part of the machine, the wadding strip with the upper and lower cloth is cut in the desired width or length in the transverse direction. In the fillings obtained directly from the fiber cables in this way, a nice soft handle is obtained as the fiber strands can slide over each other, and thanks to the fixation provided by the stitching, there is no danger of the fiber strands slipping completely and the filling is deformed or forming lumps. For this reason, it is possible to wash the products in which such padding pads are used in the washing machine when mild washing programs are applied.
Commercially available polyester filler fibers
There are many end products on the market containing special filler fibers belonging to various brands. Examples of these are Aerelle, Climarelle, Comforel, Comforel Allerban, Comforel Soft, Comforel Supreme, Dacron, Dacron 95, Hollofil, Hollofil Allerban, Hollofil Ergo 3Plus, Quallofil, Quallofil Air, Quallofil Air Allerban, Quallofil Extralife, Fillwell, Polartaguard and Inswell. can be given.
Comforel consists of small fiber balls and can be easily re-fluffed like a feather. Comforel fiber balls are designed to withstand crushing and entanglement, the product's initial shape and fluffiness are preserved for a long time, and can be machine washed and dried. It gives a soft and comfortable feeling to the user and provides a feather-like effect. Comforel Allerban fiber shows anti-dust mite, bacteria and fungus formation properties.
Allergens produced by dust mites are associated with respiratory diseases such as asthma. Allerban, an important additive to fiber filling, is an active ingredient that prevents dust mites and fungi, as well as bacterial growth. Comforel Supreme fibers are filling fibers that give extra swelling in use. It is produced from hollow fiber thought with high air content to give maximum warmth and volume. Comforel Soft fibers are thin and flexible filling fibers designed to increase the feeling of softness.
Dacron fibers are high-quality, hollow fibers that provide solid support, are durable, maintain their shape and firmness. Products made of Dacron 95° fiber can be machine washed and dried at 95°. Dacron® 95° pile fibers are designed to withstand crushing and tangling, ensuring that the pillow maintains its first day shape for a long time.
The heat-regulating Climarelle microcapsule can actively maintain the temperature and reduce it when necessary. Products containing Climarelle consist of fine and light fibers and high-tech products containing Climarelle micro-capsule, very fine and light fibers combined to provide high comfort with minimum weight.
Hollofil is a filling fiber that provides homogeneous heat distribution. Thus, the temperature differences are reduced and the body temperature is kept homogeneous. These filler fibers can be machine washed and dried. There are different types of hollophil fibers. Hollofil Allerban is an anti-mite, anti-bacterial and anti-fungal. Hollofil Ergo 3D plus products are produced from hollow fibers with 4 special channels for improved air circulation. While these reduce moisture accumulation, they create a microclimate. Hollofil II and Hollofil 808 fibers provide high insulation, are soft, have spring properties and can be restored to their original form.
Advanced four-channel fibers for high springiness and support. They provide feather-like effect, softness, comfort and support. Qualofil fibers perform 25% better than down feathers when wet and dry up to three times faster . Quallofil Air products consist of very fine and extremely light fibres. While the hollow fibers improve air circulation, they reduce the accumulation of moisture and create a microclimate. Quallofil Extra Life is a fiber that has good springing ability thanks to its 3-dimensional helical helix structure and helps to maintain appearance and shape. It provides fluffiness and softness, especially in furniture. It shows low reaction to flame.
Fillwell is a PES filling fiber with a wide range of uses in the non-woven sector. Round cross-section, hollow structure, siliconized and soft handle hollow structure fibers have a wide range of fineness. Fillwell PES filler fiber has several advantages such as wide production range, high performance and soft handle. The length of the Fillwell fiber ranges from 38 to 76 mm. Fillwell Eco-Logic is a special fiber produced in a hollow structure with properties such as elasticity, strength and volume without increasing the fiber weight.
The existing types of Fillwell Eco-Logic fibers are divided into 3 as hollow siliconized hollow and soft handle hollow. The properties of Fillwell Eco-logic fibers can be counted as high elasticity, strength, volume, reversibility, soft handle, good insulation and permanent crimp. Fillwell® Wellcare is a PES filling fiber with anti-microbial and anti-dustmite properties. During their production, they are made durable with some special additions. Fillwell®Wellcare Anti-Dustmite fibers comply with Eco-Tex standards. It prevents mite allergies, is anti-bacterial and anti-fungal.
Terital Saniwear antibacterial fiber is obtained by combining the active with organic matter without changing the mechanical and physical properties of standard polyester fiber. The required amount of active ingredient is added in melt form before spinning. In this way, the growth of non-pathogenic microorganisms, which usually cause bad odors, is prevented. This antibacterial fiber also complies with Öko-tex 100 standards. There are two forms of the fiber as cotton and filling fiber type.
Recron Fibrefill is a hollow fiber used for filling. Due to its special production technique, it provides more filling ability and softness compared to cotton and other fibers of the same weight. Recron Fiberfill is suitable for filling fiber applications such as pillows, sleeping bags, quilts. Recron Fibrefill Thermobond is a specially designed product for lap applications. It consists of a homogeneous mixture of Recron Fibrefill and low-melting polyester fiber. This fiber can be used in mattresses, furniture, insulation products. There are 6 and 15 denier, siliconized and non-siliconized versions of the fiber.
Polarguard is a continuous filament polyester fiber produced for insulation. The American army uses this fiber in specially designed sleeping bags for very cold weather. These fibers provide high heating at low weight and can be easily compressed, providing good insulation even when wet. Polarguard 3D fiber is used in sleeping bags and gloves. Polarguard and insulation products made from it show better heating properties, are softer, more flexible and more durable than products made from staple polyester. It can be machine or hand washed and dried, resistant to insects, mold and fungus.
Polarguard HV polyester filaments are designed to provide better insulation at low weight. Polarguard HV fibers are not matte, they do not tear easily when any force is applied. Polarguard HV has all the characteristics of other PES filaments such as strength, dimensional stability, keeping warm when wet. Due to its hydrophobic nature, Polarguard® HV has good insulating ability even when wet. In an independent study of sleeping bags, insulations of Polarguard® HV and staple fibers were compared. The insulation of wet sleeping bags made of staple fibers decreased by 57% compared to the insulation in the dry state. In the same conditions, the thermal insulation of Polarguard® HV decreased by only 38% compared to its dry insulation. The large triangular gap cross-section in the Polarguard® HV construction keeps it tight and warm.
Polarguard 3D fibers, which are filament polyesters, have a low tendency to clump. Polarguard® 3D is thinner than other Polarguard products. Polarguard 3D is bulky thanks to its high-cavity triangular cross-section. Thanks to its thinner structure, it is tighter, softer and more draped, and it prevents neps that will form after a long time of use. Thanks to these features, Polarguard® 3D is suitable for use in the apparel industry.
Polarguard _ filament polyester has properties such as durability, dimensional stability, good air retention and warmth that cannot hang even when wet. Unlike staple fiber insulation, there are no clumps in Polarguard. Polarguard has a hollow cross section. The large space creates higher air with less weight and keeps it warm. It provides insulation that provides good performance in sleeping bags and in harsh environmental conditions (25). Polarguard has good insulation properties even when wet due to its hydrophobic feature.
Micro-loft is a blend of microfiber fibers that are soft like down and designed to achieve higher temperature in less volume. They provide the advantages of preventing heat loss, low weight and compressibility. It is machine washable, dryable, odorless and non-allergenic.
Filling fibers other than PES
Lenzing Lyocell FILL is obtained from trees by applying environmentally friendly processes. Therefore, they are 100% natural, biodegradable fibers. Compared with other materials, they show high insulating capacity. The products obtained from Lenzing Lyocell fiber are very thin but keep warm and show good moisture management. The siliconized form of Lenzing Lyocell FILL fibers (staple length=60 mm) was first produced in 2000. It has the “Ökoteks Standard 100 Class 1” certificate due to its clean production technology.
Lenzing Lyocell FILL fibers and blends are used in mattresses, mattress pads, quilts and pillows. These fibers can be used by mixing with various fibers, especially polyester fibers. Biofresh is an antibacterial acrylic fiber. It contains triclosan as an active ingredient. Anti-bacterial properties do not go away with washing. End-use areas are listed as active wear, outerwear and sleeping bags.