認識彈性纖維 | What is Spandex?

認識彈性纖維

彈性纖維，在台灣一般習稱為『OP』，而日本稱之為『PU』，歐美國家稱之為Lycra或是Spandex。由美國杜邦公司於1959年發明。其具有很強的彈性，伸展度可達500%，且能回復原樣，比橡膠的強度更大，也更耐磨。當它第一次面世的時候，徹底改變了服裝行業的許多領域。

依據ISO 2076或DIN60001，彈性纖維(Elastan fibers)是由重量85%以上之鏈結聚胺基甲酸酯(Segmented Polyurethane)組成之線性大分子合成纖維。在美國則以"Spandex"著稱，Elastan纖維與合成橡膠纖維同樣被歸類為高彈性纖維(elastomeric fibers)因化學組成之故，此類纖維均具高變形性，也就是斷裂伸度自200%以上，通常在400-800%之間，且當外力釋放時可以很快速恢復至原來長度。 纖維具有類似彈簧般的外觀形狀，織物經染整定型處理後，更增加自發捲縮的彈性特性(Self Crimp)，賦予織物良好伸縮彈性、彈性回覆率佳及蓬鬆感。 具有低溫可染的特性，染色溫度115-130℃，可與Cotton、Acetate等天然纖維或Polyester、Nylon等人造纖維交織使用，或用於Hard core包紗等用途。染整後纖維具自然翻轉現象使織物表面呈現自然粗細的外觀色調，適用於針織、平織(梭織)等織物組織。


彈性纖維的產品應用與用途：

外套/夾克/高密度針織物/外衣布料/休閒類/時裝/套裝/帽子/褲襪/護膝/毛巾/運動衣褲。

彈性布料已成為年輕族群流行服飾和運動服是必備條件，針織布廠可以將彈性纖維直接與一般纖維織造成布料，梭織布廠則無法用彈性纖維裸紗直接織造，故先將彈性纖維(軟紗：如Lycra)與一般非彈性紗(硬紗：如聚酯、尼龍、棉、毛、麻等)結合，此種結合二種以上的紗稱為複合紗(Composited Yarn)，亦即市場上常聽到的「包紗(Covered Yarn)」。

(前往了解聚酯纖維和尼龍)

什麼是彈性包覆紗？

彈性包覆紗，故名思議，為彈性絲包覆紗線之意，而彈性絲則為俗稱 Spandex(OP)，其性質有如橡膠般之高彈性及伸縮性，其拉伸強度、拉伸應力、耐磨損性、耐老化性、耐化學藥品性上均較橡膠更為優越。彈性包覆紗即是將少量彈性纖維(比例大約5-20%)與其他主要硬紗種類一起混紡使用。硬紗種類在長纖部分有尼龍原絲、或尼龍加工絲，聚脂纖維，人工模仿蠶絲，而短纖的部分，則有棉花，亞克利，嫘縈等等。
而彈性紗包覆紗的種類以傳統包覆紗(Conventional Covering Yarn)和空氣包覆紗(Air-Jet Covered/Intermingled Yarn)為主。由於彈性包覆紗可令織物在觸感與外感不同於傳統織物，故在各類紡織品上都有應用，如平織品、經織品、針織品均有採用，從內衣到外衣，蕾絲帶到襪子，家庭紡織品到醫療用品皆應用的上。

MbX 推出的彈性緊身衣
Spandex(Elastane) Shirt by MbX

彈性纖維的製造過程：

彈性纖維(Elastane)是唯一以複絲型態出現之化學纖維。其製造方法主要有乾式法(Dry Spinning)、濕式法(Wet Spinning)、熔融法(Melting Spinning)以及反應型(Reactive Spinning)。其中80%以上彈性纖維製造係使用乾式紡絲法。一般而言，彈性纖維係由二異氰酸酯與二元醇反應之聚胺基甲酸酯所製成。

最近發展的熔融紡絲(Melt Spinning)彈性纖維因不需使用溶劑而漸受重視。為了能達到乾式紡絲彈性纖維硬鏈中順向聚尿結構的熱性質，熔融紡絲之彈性聚合體必須用較多的二異氰酸酯或多官能基之二異氰酸酯化學上交鏈。倘若欲獲得較佳之特性，熔融紡彈性體需要經熱後處理。Kuraray所生產之"Spantel"是最近發展出來的產品，"Spantel"是聚胺基甲酸酯彈性體具有聚酯乙二醇軟鏈，其與傳統聚酯彈性體比較，Spantel具有抗水解之優點。

對於彈性纖維布料的測試，在德國標準DIN 53835 T.2中，已有明確的規範。
以下就幾個彈性纖維的特性名稱先加以定義和說明：

1. 拉伸阻力：顧名思義拉伸阻力即拉伸彈性纖維所受到之負荷力，AB曲線代表第一次拉伸及回縮，A'B'則代表第五次拉伸與回縮，一般Spandex cycle test都是測試連續拉伸回縮五次之後強伸度之變化。


2. 應力衰變(Stress Decay)：係指Spandex在特定伸度下，長時間拉伸所產生之應力衰變情況，彈性纖維之應力衰變係隨Spandex伸度的增加而增大，通常試驗方法規定拉伸之300%伸度往返五次之下觀察第一次與第五次之應力衰變情況，如圖BB'所示，大部份之應力衰變都發生在前30秒內，經過5分鐘其應力衰減漸不明顯，此係因纖維內分子鏈的延緩重新結合，及重新排列所致，但這種現象是可逆的，經過一般時間之後，俟纖維內部分子鏈重新組合後，Spandex應可恢復至原鬆弛情況。


3. 握持(或回復力)：係指Spandex材質回復至其原來長度的能力，此特性用來評估Spandex織物保持原狀之能力。


4. 變形率：係指經五次cycle test所產生之變形，即AC'，此特性可用以評估Spandex內部分子鏈重新排列及再結合能力。


5. 遲滯現象(Hysterisis)：用來描述延遲或拉伸回復時應力應變性，遲滯現象初期的拉伸回復下並不顯現，但在五次往復作用後就漸趨穩定，遲滯曲線係紡織用材料在受力負載與外力釋放時所顯現的行為，遲滯現象迴圈之大小可用以表示纖維吸收與釋放所需之能量。

Spandex(Elastane)

Spandex or elastane is a synthetic fiber known for its exceptional elasticity. It is strong, but less durable than its major non-synthetic competitor, natural latex. It is a polyurethane-polyurea copolymer that was invented in 1959 by chemists C. L. Sandquist and Joseph Shivers at DuPont's Benger Laboratory in Waynesboro, Virginia. When first introduced, it revolutionized many areas of the clothing industry.

The name "spandex" is an anagram of the word "expands". It is the preferred name in North America; in continental Europe it is referred to by variants of "elastane", i.e. elasthanne (France), elastan (Germany), elastano (Spain and Portugal), elastam (Italy) and Elasthaan (Holland), and is known in the UK, Ireland, Argentina, Australia and New Zealand primarily as Lycra. Brand names for spandex include Lycra (made by Koch subsidiary Invista, previously a part of DuPont), Elaspan (also Invista), Acepora (Taekwang), Creora (Hyosung), ROICA and Dorlastan (Asahi Kasei), Linel (Fillattice), and ESPA (Toyobo).

Spandex fibers are produced in four different ways: melt extrusion, reaction spinning, solution dry spinning, and solution wet spinning. All of these methods include the initial step of reacting monomers to produce a prepolymer. Once the prepolymer is formed, it is reacted further in various ways and drawn out to make the fibers. The solution dry spinning method is used to produce over 94.5% of the world's spandex fibers.

Step 1: The first step is to produce the prepolymer. This is done by mixing a macroglycol with a diisocyanate monomer. The two compounds are mixed in a reaction vessel to produce a prepolymer. A typical ratio of glycol to diisocyanate is 1:2.

Step 2: The prepolymer is further reacted with an equal amount of diamine. This reaction is known as chain extension reaction. The resulting solution is diluted with a solvent (DMAc) to produce the spinning solution. The solvent helps make the solution thinner and more easily handled, and then it can be pumped into the fibre production cell.

Step 3: The spinning solution is pumped into a cylindrical spinning cell where it is cured and converted into fibres. In this cell, the polymer solution is forced through a metal plate called a spinneret. This causes the solution to be aligned in strands of liquid polymer. As the strands pass through the cell, they are heated in the presence of a nitrogen and solvent gas. This process causes the liquid polymer to react chemically and form solid strands.

Step 4: As the fibres exit the cell, an amount of solid strands are bundled together to produce the desired thickness. Each fibre of spandex is made up of many smaller individual fibres that adhere to one another due to the natural stickiness of their surface.

Step 5: The resulting fibres are then treated with a finishing agent which can be magnesium stearate or another polymer. This treatment prevents the fibres' sticking together and aids in textile manufacture. The fibres are then transferred through a series of rollers onto a spool.

編排整理 Edited: ACOTEX Fabric Talks 布料指南