Elastic fiber dyeing, finishing and finishing

Song Xinyuan (Donghua University, Shanghai 201620)

Abstract: This paper systematically introduces the structure and elasticity of various elastic fibers, including elastic yarn, spandex, polyether ester elastic fiber, polyolefin elastic fiber, hard elastic fiber, PTT and PBT fiber, and composite polyester elastic fiber. The relationship between structure and elasticity. Focusing on the elasticity of these fibers, the paper analyzes and introduces the dyeing and finishing characteristics of elastic fiber-containing textiles, especially pointing out that such textiles are prone to "creep" and "stress relaxation" during dyeing and finishing. And the "fatigue" phenomenon (deformation and recovery is different from conventional textiles), the temperature, tension and time during dyeing and finishing should be reasonably controlled. The importance of the relaxation treatment is also demonstrated. Finally, the main textiles containing elastic fibers are briefly introduced. Dyeing and finishing process, additives and precautions.
Key words: elastic fiber textile; elasticity; dyeing and finishing; auxiliaries CLC number: TQ340.47 Document code: AArticle ID:1004-0439(2011)03-0001-014
Synthetic fiber has been developed for seven or eight decades. It was originally used for clothing. There are only a few commonly used fibers, such as nylon and polyester. Since 1960, with the improvement of synthetic fiber performance, the variety has been expanding. Special fibers, microfibers, elastic fibers and industrial high-strength fibers have developed rapidly. Among them, elastic fibers are not only used in various high-performance garments, but also in decorative textiles. Currently, synthetic fibers are mainly sustainable and recyclable. The development of biodegradability and nano-functionality. The same is true for elastic fibers. A number of new elastic fibers have emerged, mainly through the following ways: (1) changing the basic material, ie the molecular structure of the polymer; 2) changing the supramolecular or microstructure of the polymer; (3) blending or mixing different polymers into appropriate additives; (4) changing the fiber morphology, such as fiber thickness, cross-sectional shape, degree of curling, etc.; The filament component is compounded or plied to form a double or multi-component composite fiber; (6) the surface of the fiber is modified or the surface structure is changed; (7) the filament is twisted or compounded to change the number and shape of the yarn. The above ways can be changed The properties of fiber materials (including elastic function). The most important way is to change the basic composition of the fiber (ie, the molecular structure of the polymer). In recent years, many new polymers have been developed and a large number of elastic fibers with different molecular structures have been spun. Secondly, different polymers are blended or compounded. Since the fibers contain a variety of polymers, their properties, including elasticity, will change. By changing the mixing and mixing modes and changing the mixing ratio of the components, the properties can be further changed. For example, the two-component composite fiber can be greatly improved in elasticity after being crimped; in addition, changing the cross-sectional shape of the fiber or modifying the surface or changing the surface structure can also change its properties, including improving the elasticity of the textile; Multifilament ply, changing the number of strands, or twisting the yarn, etc., can improve the elasticity of the textile.
At present, textiles are mainly developed in the direction of toughness, safety, durability, fineness, environmental protection, comfort, beauty and easy care. Safety, environmental protection and comfort are especially important, and these functions are closely related to the elasticity of fibers. The elasticity of textiles is a kind of Important taking performance, it refers to the ability of materials to resist and recover deformation. Elastic fiber refers to fibers or tows with high elongation and high resilience. Different countries or regions have different definitions. According to the elasticity of the American Society for Testing Materials The definition of the body refers to the material that is repeatedly stretched to at least 2 times the original length at room temperature, and can quickly return to the original length after releasing the tensile force. However, for the polyurethane elastic fiber, the tensile strength can be released after stretching the original length by 3 times. Quickly restore the original long fiber. In recent years, textiles have become more and more elastic. In order to meet the needs, many new elastic fibers and textiles have been developed. These new elastic fiber textiles have high processing requirements, especially for dyeing and finishing. The processing is very difficult. To this end, this paper first introduces the structure and elasticity of elastic fibers, and then discusses the dyeing and finishing of elastic fiber textiles.
1. The category of elastic fibers or filaments and the elasticity of elastic textiles are mainly determined by their structure, including the chemical structure of the fibers, the supramolecular or microstructure of the fibers, the morphology of the fibers or yarns, and the texture of the textiles. Controlling the above structure can improve or improve the elasticity of textiles.
For ordinary textiles, due to the general structure of fibers, yarns and textiles, although it has certain elasticity, the elasticity is not high. For elastic textiles, elastic fibers or yarns are selected and woven into certain Organizational structure, so the elasticity is good.
The elasticity of a fiber or yarn is mainly determined by the polymer molecular structure of the fiber. That is, the elastic fiber or yarn currently on the market is mainly composed of an elastic polymer. These elastic polymers have a special molecular chain structure and a supramolecular structure. High elastic deformation occurs after stress, which is a reversible deformation characteristic of these high polymer materials. When the temperature is higher than the glass transition temperature, the polymer segment in the amorphous region can move freely, and the entire polymer chain In the high-elastic state, which still cannot move, when the external force is applied, the movement of the chain may cause the macromolecular chain to partially curl or stretch, and the deformation can reach 100%~1 000%. The material becomes soft and elastic; after the external force is removed It will gradually return to its original state as time goes by, some of the deformation will recover quickly, and some deformations can only recover slowly. The polymer suitable for making elastic fibers is usually a block copolymer, and the macromolecules are long segments with good flexibility. (soft segment) and rigid short segment (hard segment) alternately. Soft segment makes fiber easy to deform and stretch, while hard segment is stronger due to mutual interaction, and some even establish covalent cross Bonded to give fiber strength Degree and resilience. At present, the high polymer mainly has block polyurethane and other synthetic copolymers. The elastic fabric mainly relies on the elastic fibers mixed in the warp and weft to improve the elasticity.
Elastomeric textiles can also impart good elasticity by changing the supramolecular or microstructure of the fibers. Other textile fibers or yarns have good morphological structure or structure, which makes them have good elasticity. The yarns with strong twist impart a good resilience. Different elastic fabrics can be selected according to their use, respectively, and the yarn or fabric structure can be used to improve the elasticity. In short, the types of elastic fibers or filaments can be classified into the following. Several categories.
1.1 twisted textured yarn or elastic filament twisted textured yarn commonly known as elastic yarn, usually pre-oriented silk or full-stretched silk, etc., through the twisting deformation or twisting-setting-untwisting process, processing into small springs Curled filaments. They have a high degree of elastic stretch and fast recovery. The elasticity of the filaments is not strong. The elasticity of the filaments comes from the elasticity of the spring-shaped strands after shaping, rather than the elasticity of the molecular chains. After the shape disappears, the elasticity of the thread also disappears, because the elasticity of the polymer is not high. The textile made of the elastic yarn, especially the dyeing and finishing of the knitted fabric and the non-elastic textile made of the same polymer. Basically similar, it should be noted that during the dyeing and finishing process, the spring shape of the wire should not be lost or loosened. Therefore, the tension should be small when processing at high temperature, and the time cannot be long. Because the elasticity of the textile becomes loose or disappears as the spring shape becomes loose. It is greatly smaller.
1.2 Polyurethane elastic fiber Polyurethane elastic fiber [1] is the most important type of elastic fiber commonly known as spandex, which is made of elastomer or elastic polymer. The so-called elastomer is easy to deform under the application of external force, but when external force After removal, the original polymer can be restored. The most typical example is vulcanized rubber. Their molecular chains are soft, the interaction force is small, and they are easy to move and deform. They are amorphous polymers. After the mesh structure, the deformation recovery ability is greatly improved, so the elasticity is very good. In the past, many high-elastic textiles were woven into a part of the rubber yarn to improve the elasticity. Because of the many disadvantages of the rubber yarn, the elastic textile is becoming less and less.
The elastic fibers made of elastomers mainly include polyurethanes, polyether esters, polyolefins, polycarbonates, etc. Their "soft" and "hard" segments have different chemical compositions and structures, so the elastic size, dyeing and finishing Processing performance will be different.
Polyurethane elastic fiber has been mass-produced and applied, and it is developing rapidly. It is a kind of high-elastic fiber widely used in various textiles. Its elasticity originates from its molecular structure, firstly the embedding of "soft" and "hard" segments. Segment copolymer network structure, also known as "segment" network structure. However, this fiber has different spinning processes depending on the block copolymer. After forming different "segment" network structures, the elasticity and dyeing and finishing properties are also Different. The "segment" structure of the copolymer is obtained by the stepwise polyaddition of diisocyanate. The low molecular diisocyanate reacts with the low molecular dihydroxy compound to produce shorter "hard" segments. Because of their various polarities The groups (especially urea groups) can form more hydrogen bonds with each other, and are easy to crystallize and crosslink between molecules. Under the action of lower stress, the segments are basically not deformed and can be prevented. Slip between the macromolecules of the fiber, and provides a node for the rebound of the "soft" segment after a large elongation, and also gives the fiber a certain degree of strength, modulus and wear resistance. "The chain segment is made up of long chain dihydroxy compounds (macromolecule II) The composition of the alcohol has a relative molecular mass of 1,500 to 3,000, a melting point of <50 ° C, a segment length of about 15 to 30 nm, about 10 times the length of the "hard" segment, and a low glass transition temperature Tg ( It is -50~-70 °C). The long-chain diol can be polyester, polyether, polycarbonate, polyacetone and their composites. They are difficult to crystallize and are in a high elastic state at normal temperature. Large deformation can occur under small stress, making the polyurethane fiber easy to stretch. According to the "soft" segment containing ether or ester, polyurethane elastic fiber is divided into two major categories, polyether and polyester. Fibers are not only different in elasticity, but also in dyeing and finishing properties, chemical stability and aging resistance. In general, polyethers are softer, more deformed by force, and fiber network structure after stretching. It is very obvious that when the "soft" segment of the polyester type is stretched by 200%, the molecular chain is continuously oriented along the fiber axis, but no crystallization occurs; the polyether type not only is oriented but also crystallizes because of the polyether molecule. The chains are more easily close to each other and arranged in a regular manner. From the perspective of dyeing and finishing, polyester-type polyurethane fibers are resistant to oxidation and heat. Preferably, the disperse dye adsorption is also strong; polyether detergent resistance and fungus resistance so better processing conditions of both the product and the applicable different long chain molecular structure of polyurethane as follows:.

The molecular soft segment of polyurethane fiber is composed of macromolecular diol compound segments, their molecular interaction is weak, the molecular segment is easy to move, and the soft segment quality accounts for 65%~90% of the total polyurethane fiber quality. Elongation or shrinkage and curling. When the fiber is stretched, it tends to be fine and elongated, and the order is improved. The order of the soft segments is different after stretching. It has been pointed out that the soft segment inside the polyurethane filament is not stretched. It is amorphous and non-oriented, but after 200% tensile elongation, the fibers composed of polyester diol are oriented along the molecular chain of the fiber axis, but no crystals appear, and the fiber along the polyether diol The fiber axis is not only oriented, but also crystallization. This is due to the different tendency of the two molecular chains to crystallize. The polyurethane hard segment is shorter and contains more polar groups, mainly urea groups and urethanes. Their molecular chains are not easy to move freely, and there is a strong molecular force between them (including the formation of hydrogen bonding), so the hard segment is directly related to the strength and heat resistance of the fiber, and is also a key component of the elastic restoring force. It and the soft segment form a "section" network structure, Fiber excellent elasticity.
At present, polyurethane elastic fibers are mainly produced by a solvent spinning process, and a large amount of solvent (for example, DMF, etc.) is required. These solvents have problems such as environmental pollution and adverse effects on human health, and therefore, the production of melt spinning production technology has been vigorously developed in recent years. The fiber produced is not as good as the traditional solvent method in terms of elastic recovery rate, hydrolysis resistance and heat resistance. However, as the spinning technology continues to mature, the product performance has gradually approached or reached the level of traditional fiber, so the melt spinning There are more and more fiber varieties. Polyurethane elastic fibers produced by different processes are not completely identical in chemical composition and supramolecular structure, and their elasticity and dyeing and finishing properties are obviously different. Attention should be paid to dyeing and finishing. In terms of the products produced, the performance of polyurethane elastomers produced by using different raw materials is also very different. For example, the fibers produced by polycaprolactone diol have good water resistance, and the heat resistance produced by polycarbonate diol is good. The polyester polyester oligomer can improve the elasticity as a crosslinking agent, and the addition of a suitable diamine compound can also improve the dyeability, etc. In order to meet market demand, Also produces a number of high moisture absorption and desorption spandex, heat setting spandex and antibacterial, abrasion resistance, chlorine, antistatic, absorbent, deodorant performance spandex, breathable, warm, etc. [2]
1.3 Polyetherester Elastic Fiber Polyetherester Elastic fiber is an elastic fiber obtained by melt spinning of polyester and polyether copolymer. It was first produced by Teijin in 1990. Polyetherester elastic fiber and polyurethane elastic fiber structure. Similarly, it also has a "segment" structure. The "soft" segment is mainly a polyether segment. It has good flexibility and a long chain, so it is easy to elongate and deform. The "hard" segment is a polyester segment. It is relatively stiff, easy to crystallize, and has a short chain. When the fiber is deformed by force, it acts as a joint, giving elastic recovery properties and determining the strength and heat resistance of the fiber. It is not available in both polyether and polyester segments. The ability to form covalent bonds is also difficult to form hydrogen bonds. Therefore, the molecular chain network nodes are mainly crystalline units, that is, crystalline units formed by polyester segments. The "segment" structure of such elastic fibers is schematically as follows:

Wherein R1 is a polyether alkyl group, the polyether chain is long, and the flexibility is good, and is a soft segment; R2 is an alkyl or aryl group of a dibasic acid, and the segment is relatively rigid, short, and easy to crystallize. , is a hard segment; R3 is an alkyl group of a diol, the diol segment is also short, easy to crystallize, and the ester segment acts as a hard segment, and is relatively compliant only when the R3 chain is long. More elastic fibers are PET as a hard segment, PEO is a soft segment, which can be expressed as PET/PEO. It is divided into strong, medium and high strength elastic fibers. As can be seen from Table 1, various polyether esters are elastic. The fiber not only has high strength but also good elasticity. When the elongation is 50%, the elasticity of the medium-strength elastic fiber is equivalent to that of spandex. Their melting point is also high, and it is blended with PET fiber, which can be dyed at 120~130 °C. Polyester fiber can also be processed into elastic textiles. In addition, they are excellent in light resistance, chlorine bleaching resistance, acid and alkali resistance, etc., and are better than ordinary spandex. Because of good acid and alkali resistance, they are woven with polyester. The fabric can also be alkali-reduced to improve the drape of the fabric, so the elastic fiber can be used in silk garments. The fiber raw material is cheap, easy to produce and process, and is a kind of promising fiber. At present, Rexe of Japan Teijin Co., Ltd. has been commercialized and has received market attention.

1.4 Polyolefin elastic fiber Polyolefin elastic fiber is an elastic fiber made of polyolefin copolymer, mainly obtained by copolymerization of ethylene (mass fraction ≥ 95%) with other olefins. The copolymer also has "soft" and "hard" "Structure: a "hard" segment region of a network system consisting of covalent bonds (crosslinking points) between crystals and macromolecular chains, and a "soft" segment region composed of longer flexible polyolefin chains. The chain is easy to move and belongs to an amorphous arrangement. This "soft" and "hard" segment structure gives fiber elasticity. It is represented by the Dow Chemical Company's Lastol fiber, also known as Dow XLA fiber, which is officially named Elastolefin fiber. The microscopic network structure of this fiber and the cross-sectional shape of the 155.6 dtex fiber are shown in Figures 1 and 2. [3]

The polyolefin elastic fiber molecules do not contain polar groups, and the linkage between the molecular chains depends on crystals and covalent bonds. Due to the high proportion of non-polar polyolefin chains, the molecular chain of the amorphous region is longer and easy to move freely. The average crystallinity is about 14%. The crystallinity, crosslink density and the compliant chain length determine the elasticity of the fiber. They have large deformation under low stress and soft elasticity.
Unlike the above two kinds of thermoplastic elastic fibers, polyolefin elastic fibers have a crystal node and a covalent bond crosslinking point, so as the temperature rises to about 80 ° C, even if the crystal melts, the covalent bond still exists until 220 ° C The fiber can still maintain its shape. When the temperature is lowered, the crystal network is re-formed, and the fiber can quickly restore its strength and elasticity. The strength and heat resistance of the elastic fiber are determined not only by the degree of crystallinity, but also by covalent bonds. The network structure is closely related, that is, the length of the polyolefin chain and the distribution of the covalent bond, the density has an effect on the strength and heat resistance, but the distribution and density of the covalent bond often play a leading role. As can be seen from Figure 3, At 25 °C, the two kinds of elastic fibers are intact in shape and smooth in surface; at 220 °C, the spandex has broken and broken into pieces, and the XLA fiber remains in its original shape without decomposition and fracture. Although its physical and mechanical properties have occurred. A great change (because the crystal has melted at around 80 ° C), but because the covalent bond crosslinked network structure has not been destroyed, the fiber morphology can still be maintained intact. The melting and recrystallization of the crystal is reversible, when the temperature drop When the crystal network is re-established at room temperature, the physical and mechanical properties of the fiber can be basically restored. Therefore, the elastic fiber is suitable for the heat-resistant textile product, and is not easily damaged during the dyeing and finishing process. The dimensional stability is good and the elongation is not easy. Deformation and wrinkling. Also based on this microstructure, textiles do not require preheating and shaping, and other thermoplastic fiber textiles require preheating to improve their processing stability. So this fiber is very suitable for silk, wool, Acrylic, nylon and other high temperature sensitive fibers are blended or interwoven, and are of course also suitable for blending or interlacing with fibers that require heat setting.

XLA elastic fiber has obvious difference in elasticity and other elastic fibers due to its special microstructure. As can be seen from Fig. 4, XLA fiber has greater elongation and restoring force under lower stress, indicating that it has softer elasticity. , that is, the stress required for stretching is small, the recovery is very good, and the finished textile is more comfortable and comfortable when worn. Of course, when the fiber textile is dyed and finished, the tension should be small, and it is not suitable for strong pulling, so as to avoid excessive deformation.

XLA fiber is a hydrophobic fiber, the molecule does not contain polar groups, so its chemical stability is very good, not only resistant to strong acid and alkali, but also resistant to various oxidants. Spandex has poor chlorine bleaching resistance, and XLA fiber resistance Chlorine bleaching is very good. However, since XLA fiber is a kind of polyolefin fiber, it has poor resistance to organic solvents, and many solvents have strong swelling effect on it. In addition, the light resistance of XLA fiber is slightly higher than that of commonly used fiber. Poor, but better than spandex, which is related to its existence of a covalent bond cross-linking point.
XLA fiber itself does not have suitable dyeing dyes, but it is suitable for blending or interlacing with other fibers into various elastic textiles. Due to heat resistance, chemical resistance, and special mechanical properties, elongation recovery performance is good, and photodegradation resistance is also better. Good, so it has been developed for a variety of blended or interwoven textiles, including textiles blended or interwoven with wool, cotton, etc., especially swimwear, underwear, anti-wrinkle elastic fabrics, such as elastic denim, non-iron business wear and leisure sports Shirts, etc. These garments have better drapability and feel than spandex textiles, and because of the fibers, the garments remain elastic after repeated dry cleaning. In addition, the fibers do not release volatile organic compounds. Without heavy metals, the finished garments can be recycled, also known as "environmentally friendly" elastic fibers.
It has recently been reported that Dow Chemical will withdraw from the polyolefin-based elastic fiber “Dow XLA” (it is expected to complete the retreat after 6-18 months). From the perspective of developing elastic fiber textiles, it is hoped that new similar fibers will appear. Or develop alternative products of this type of fiber to produce elastic fiber textiles with excellent performance.
1.5 Hard Elastic Fibers The above elastic fibers are all soft elastic fibers, which undergo large deformation and recovery under lower stress. For example, polyurethane elastic fibers are stretched, and the long chain of the crimped metal is stretched when the tensile force is released. After that, the long molecular chain can be restored to its previous state. From a thermodynamic point of view, the elasticity comes from the degree of freedom (or chaos) of the molecular chain, that is, the change in the entropy of the system. Therefore, the crystallinity of the above fibers is very low (because it is high) The degree of freedom or entropy of the molecular chain of the crystallinity fiber is very low, and the elasticity of the fiber is not high. However, some fibers obtained under special processing conditions, such as polypropylene (PP), polyethylene (PE), etc., They are not easily deformed under low stress (because they have a higher modulus), but they also have better elasticity under higher stress, especially at lower temperatures, so these fibers are called hard elastic fibers.
The deformation and recovery of the hard elastic fiber are significantly different from those of the foregoing elastic fiber. For example, when the hard elastic PP fiber is stretched and then subjected to the second stretching, the modulus and strength are greatly reduced. However, if the stress is removed, a section is placed. After the time, or raising the temperature to make it relax sufficiently and then performing the second stretching, the deformation recovery is substantially close to the first curve. This is because the soft elastic fiber not only undergoes the aforementioned soft elasticity when stretched and recovered. The long segment of the crimped molecule of the fiber is stretched and retracted, and some microporous structure changes are formed along the stretching process, and their wafer network structure also changes. Only after these structural changes are gradually repaired Return to the original stretching and recovery state, so they will be deformed and recovered under higher pressure, so it is called hard elastic fiber.
It can be seen from Fig. 5 that when the hard elastic polyvinylidene fluoride fiber is stretched, the oriented wafer is slowly separated, the amorphous molecular chain undergoes a process of crystallization transformation and plastic deformation, and two yield points appear in the deformation curve. Wafer separation and plastic deformation, that is, not only the elongation and retraction of the crimped molecular chain, but also the deformation of the amorphous region structure and the rotation and separation of the crystal region, and the enthalpy of the system also changes. The repair time is longer after stretching and deformation. Due to the special microporous structure between the wafers, the fiber has good elasticity. [4]

At present, hard elastic fibers are not widely used in textiles, but because of their different elastic characteristics, they can be developed for some special textiles.
1.6 PTT and PBT Elastic fiber PET fiber is one of the most important synthetic fibers. It has many excellent properties and proper elasticity. From the molecular composition, it can also be divided into two parts: hard component and soft component. as follows:

Since the soft component chain is not long, the fiber is easy to crystallize and has elasticity. In the PTT and PBT fibers, the ethylene glycol in the PET fiber is replaced by propylene glycol and butylene glycol, respectively, and the methylene group of the soft component in the long chain of the molecule is composed of Two of them are replaced by three and four, respectively. Not only the chain length of the soft component grows, but also the softness, and the lattice structure of the fiber and the planarity of the molecular chain are also accompanied by changes, so that the deformation recovery of the molecular chain is different from that of the PET fiber. In particular, PTT fibers contain 3 methylene groups in the soft component, and there is a so-called "odd carbon effect". The odd methylene chain makes the benzene ring in the polyester unit not in the same plane as the 3 methylene units. The two carbonyl groups can only be arranged in a 120° staggered arrangement, thereby making the long molecular chains of PTT spirally arranged. The conformation of long molecular chains in PTT crystals is studied by X-ray and electron diffraction, and it is found that -O-CH2—CH2— CH2-O—the unit has the lowest energy trans-side-side-trans-conformation, and the molecular chain has a zigzag conformation (as shown in Figure 6), making the PTT long molecular chain have the same coil spring. Elasticity, not only low fiber modulus, but also good internal recovery. Because of this spiral structure, outside Under the action of the "by-side" unit, the chain rotation is easy to transform into a "trans" conformation, the molecular chain is easy to elongate, and the configuration of the molecular chain does not change during the rotation of the bond. The conformational transition is reversible. After the external force is removed, it will quickly return to its original state.

The Z-shaped conformational molecular chain of PTT fiber contains two molecular chain repeating units in the C-axis direction in the unit cell. There is only one PET and PBT fiber, so the crystal lattice size is large, incomplete, and the crystallinity is low. The conformation of the amorphous region with high content and easy deformation ".Z" shape gives high elasticity, but due to the "Z"-shaped conformation in the crystal phase, the long molecular chain cannot be conformed to change very quickly after the force, and there is no The molecular chain arrangement of the shaped region is basically non-oriented, so the conformational change does not directly produce a high elastic deformation. Therefore, it is generally believed that the good elasticity of the PTT fiber originates from the "odd carbon effect" and needs further study. However, it has Good elasticity gives the textile good morphological stability characteristics, so this fiber is also called shape memory fiber. It can be seen from Figure 7 that the PTT fiber has better elasticity than PET and PBT fiber. PBT fiber elasticity ratio PET Well, the reason is that PBT has 4 methylene groups, the chain is relatively long, and after stress, the lattice structure will be reversibly converted from α-crystal form to β-crystal form. However, it is still worse than PTT.

1.7 Composite polyester elastic fiber has many ways to improve fiber elasticity or develop high elastic fiber, but the main way is to synthesize new polymer molecules and make certain supramolecular structure. The new polymer molecule is the foundation, fiber The supramolecular structure is the key. Although the elasticity of PTT fiber is higher than that of ordinary synthetic fiber such as PET, it is lower than that of spandex. Although it can meet the requirements of general textiles, it can not meet the needs of high elastic products. To further improve the elasticity of this fiber, Developed a two-component composite crimped elastic fiber by conjugated spinning of two polymers with different structures and properties, the elasticity of which is based on the shrinkage or elongation difference of the two components in the fiber. PTT/PET side-by-side composite spinning, after heat treatment, due to the different shrinkage of PTT and PET, the composite fiber is spirally bent around the fiber axis to form highly crimped fibers with great elongation and elastic recovery. The current representative product is PTT/PET bicomponent fiber T-400 produced by Invista. Its longitudinal and cross-sectional shapes are shown in Figure 8. This elastic fiber has good performance.

At present, a large number of elastic fibers used in the market, in addition to spandex, some new elastic fibers (such as composite polyester, polyolefin elastic fiber, etc.) are used more and more. The former such as T-400 fiber, the latter such as Dow XLA fiber. The European Commission has officially proposed to add these two types of fibers to the list of elastic fibers, and define the former to contain more than two kinds of elastic fibers composed of different linear polymers with ester groups, the latter being composed of 95% partially crosslinked ethylene hydrocarbons. An elastic fiber composed of at least one other olefin. These two fibers are referred to as Elasterell-P and Lastol in the US Textile Fiber Product Identification Act.
These elastic fibers have different compositions and different production methods. Their morphology and properties (including elasticity and dyeing and finishing properties) are different. Observing their longitudinal and cross-section, the longitudinal surface of the composite polyester elastic fiber has obvious grooves and cross-section. The cross section is "8" shape, and the fiber is fine; the longitudinal surface of the polyolefin elastic fiber is relatively smooth, the cross section is oblong, and the fiber is relatively thick; the longitudinal and cross-sectional morphology of the spandex monofilament is similar to that of the polyolefin elastic fiber. However, its shape varies greatly with the variety, and its performance is also significantly different from that of polyolefin elastic fiber. Moreover, the longitudinal direction of spandex multifilament often shows that two or more fibers are stuck together, so the cross section is dumbbell-shaped and the fiber is thicker. .
The physical and chemical properties of these kinds of elastic fibers are also different. The spandex can be dissolved in dimethylformamide or 75% sulfuric acid, while the polyolefin elastic fiber is insoluble in concentrated sulfuric acid (95%~98%), and the composite polyester elastic fiber is It can be dissolved in concentrated sulfuric acid, but insoluble in dimethylformamide or 75% sulfuric acid. Due to different chemical composition, the infrared spectra of these fibers are completely different. The composite polyester elastic fiber exhibits obvious infrared spectrum of polyester, polyolefin elasticity. The infrared spectrum of the fiber is similar to that of polyethylene, except that it also has a characteristic absorption peak of cross-linking of the vinyl group. The infrared spectrum of the spandex is significantly different from the above two kinds of fibers, and the characteristic absorption peak is a urethane group. The absorption peak. Elemental analysis also found that in the polyolefin elastic fiber, in addition to the main components of carbon and hydrogen, there are also oxygen and silicon elements, which indicates the presence of siloxane component in the fiber crosslinker, these properties can be used Identification of elastic fibers.
Because of the different chemical composition and structure, fiber supramolecular structure and morphological structure of these elastic fibers, their basic properties and dyeing and finishing properties are different. Some performance comparisons are shown in Table 2. PTT/PET composite fibers are permanently curled. It has elasticity and can be directly processed by textile without coating. Because of its low initial modulus, it is soft and smooth, and it is not easy to relax. It has good chemical stability. It is a polyester fiber with good dyeing performance and dyeing temperature. Low, easy to dye dark.

Elastic fibers have evolved from rubber elastomers in the direction of diversification and functionalization. With the elastic fiber, mechanical properties, thermal and chemical stability, dyeing and other dyeing and finishing properties, elastic fiber applications Constantly expanding. Due to the chemical composition of the elastic fiber, the molecular structure, the supramolecular and micro-structure of the fiber, the morphology and surface structure of the fiber, and the processing of twisting and compounding, the dyeing and finishing characteristics of the textile are different. Dyeing and finishing The process conditions should be formulated according to the characteristics of different elastic fibers, and the elastic fibers should not be damaged as much as possible.
2. Elastic fiber textile dyeing and finishing characteristics The dyeing and finishing properties of elastic fiber are related to the chemical and physical structure of the elastic fiber, and are related to its elastic structure and composition. How to maintain elasticity or minimize the dyeing and finishing process The damage to elasticity is the first problem to be aware of.
From the chemical composition point of view, some elastic fibers and ordinary fibers are the same or different. For example, twisted textured yarn or elastic yarn, the composition of which is mostly polyamide, and the dyeing and finishing performance of ordinary polyamide fiber is basically the same. Also like PTT, PBT and composite polyester elastic fiber (T-400 fiber), their chemical composition is polyester, chemical stability is similar, but slightly different with the chain length of the glycol. They can be dyed with disperse dyes, dyed The temperature and suitable disperse dyes vary from diol to alcohol. The difference in diols results in differences in the hydrophobicity, supramolecular structure and dyeing rate of the fibers. In addition, polyetherester elastomers contain polyesters and polyethers. Structure, chemical stability, dyeing properties and polyester fiber are close to each other. It can also be dyed with disperse dyes, but the disperse dyes and dyeing conditions used are more different from ordinary polyester fibers. Other elastic fibers, such as polyolefin and hard. Elastic fibers, whose chemical composition is polyolefin or its derivatives, lacks polar groups in the molecular composition, is a hydrophobic fiber, and has good chemical stability, but it is difficult to dye. The chemical stability of spandex is not very good. Don't be resistant to chlorine bleaching, poor light resistance and poor dyeability. There is no suitable dyeing. Although disperse dyes can be dyed, they are not dyed deeply and have poor color fastness. Some newly developed functional spandex molecules are introduced. Some special compositions, dyeing, chlorine resistance, etc. have been improved. It can be seen that due to the diversity of chemical compositions, elastic fibers have different dyeing and finishing characteristics, so attention should be paid to their chemistry during dyeing and finishing. composition.
From the perspective of physical structure, mainly supramolecular structure and morphological structure, different elastic fibers are also very different. In particular, the composition and structure of the deformation and recovery of the fiber are closely related to the dyeing and finishing properties. Or elastic yarn, its elasticity mainly comes from the shape of a coiled spring-like fiber, which is formed by twisting-setting-untwisting. Therefore, after the dyeing and finishing process is subjected to tension, especially at high temperatures, Change the shape of the curled spring to weaken its elasticity. The tension and temperature of the dyeing and finishing process should be carefully controlled, not subject to excessive tension and excessive temperature, especially repeated processing under damp heat conditions, and should maintain low tension. Or after the tension processing, the relaxation treatment for a certain period of time under no tension is beneficial to improve the elasticity.
For most elastic fibers, their elasticity mainly comes from the segmental structure of "soft" and "hard" molecular segments, but the "hard" segments of different elastic fibers are very different. Polyurethane, polyether ester, PTT The hard segments of elastic fibers such as PBT and hard elastic are stiffer or crystallized, the molecular chains are closely arranged, and a strong force is established between the molecular chains, and becomes a molecular chain network node, so the restoring force is strong, so that the fibers It has good elasticity. However, due to these forces between the molecular chains, it is easy to disassemble when subjected to high temperature or solvent, and the molecular chains move with each other to make the elasticity disappear. Therefore, the network nodes established by this structure are in high temperature or solvent. Will be destroyed, the so-called "hard" segment network nodes will disappear or the crystal will disappear, so that the fiber loses the restoring force, the elasticity is weakened.
For polyolefin elastic fibers, for example, the "hard" segment of XLA fiber is both crystalline and covalently bonded. The crystal melts as the temperature rises to about 80 °C; but the covalent bond does not break, so at 80 Above °C, it still has good elasticity and can be processed at higher temperature. Of course, when it is above 80 °C, the physical and mechanical properties of the fiber will change greatly due to the melting of the crystal, so the processing tension should be low, and it is better to be 80. When it is below °C, it will be relaxed for a certain period of time to recrystallize the molecular chain and improve the elasticity and mechanical properties.
It can be seen from the above that when the elastic fiber textile is dyed and finished, the control of processing tension and temperature is very important. Not only the maximum tension and temperature are controlled within a certain range, but also the time of tension and high temperature treatment. The longer the time, the elastic structure of the fiber The greater the damage or elastic loss, so the fiber textile dyeing and finishing process should be carried out under low tension and low temperature. It should also avoid using solvents or additives that have swelling effect on the fiber. The processing time under tension should be short, even if the tension It is not too big, and it is not suitable for tension for a long time. Because the fiber and the yarn are subjected to tension, although the deformation amount is proportional to the tension within a certain period of time, under a certain tension, the deformation amount will increase with time.张力后,变形量也不会立即消失,因为纤维和纱线的变形有急弹性变形、缓弹性变形和塑性变形.在一定张力作用下,变形随时间延长而增加,即发生“蠕变”现象.反之,在保持恒定变形时,纤维内部的应力则会随时间延长而不断下降,即发生“应力松弛”现象.发生蠕变和应力松 都起因于纤维的结构,包括分子链结构、超分子结构和形态结构.纱线的变形还和纱线内纤维的相互滑移和错位有关.对弹性纤维及其纱线来说,虽然产生弹性的组成和结构不同,而且它们的弹性比普通纤维高,但在不同张力下弹性水平不同,急弹性、缓弹性和塑性变形程度相互差别很大,蠕变和应力松弛特性也各不相同.
染整加工时,纺织品的经向会长时间受到较大的张力作用.例如在连续精练加工、染色和后整理时,为了使纺织品连续运转,经向都要保持一定的张力.即使张力大小恒定,由于作用时间长,纺织品的形变(主要反映在长度上)会随时间延长而不断增加,即纺织品会不断伸长,并引起纬向不断变窄.当张力消除后这些变形不会完全回复,部分可以立即回复,部分缓慢回复,部分永远不会自然回复.长时间作用会出现“蠕变”,使纺织品尺寸不规整,形态不稳定.例如在后加工或应用时会收缩,特别是低张力下洗涤时会发生所谓“缩水”现象,使服装尺寸和形态变化,降低其品质.弹性纤维由于容易变形,所以“蠕变”现象特别明显,张力消失后,虽然变形大部分可以回复,但是当受到的张力较大,产生的变形量又很大时,形变完全回复很困难,经向伸长或纬向的收缩量很难完全消失.当长时间受到变化的张力作用,或者长时间反复受到较大张力作用后,纺织品经向各批段的伸长率是不同的,纬向的宽度也不相同,常常会出现所谓“荷叶边”现象,即门幅不规整,并很难消除.不同弹性纤维由于弹性回复力不同(有的属软弹性纤维,有的属硬弹性纤维),它们在不同张力下的变形和回复特性是不同的,出现上述伸长和收缩现象也是不同的,在染整加工时应加以注意.染整加工时常出现“应力松弛”现象,最典型的例子是拉幅或热定形时织物纬向张力会不断变化.拉幅或热定形加工时,通过给织物纬向施加一定的张力使织物平整, 消除折皱印和使门幅规整划一,其目的是消除纤维的内应力,使纤维分子链发生重新排列,建立较稳定的结合,使纤维或纺织品的形态或尺寸稳定.弹性纤维容易变形,受到张力作用后,分子链发生相对滑动,且这种形变量不仅与应力大小有关,还和作用时间有关.作用时间延长,随着分子链的不断运动,特别是“软”链段分子链的运动,纤维或织物受到的应力会逐渐减小,即发生“应力松弛”现象.纤维或织物的应力减小后,会使织物的平整度和门幅规整划一性降低,时间变化或加工时间过长都会降低产品的质量.所以要严格控制弹性纤维的拉幅或热定形时间.
在一定张力下,或者一定门幅下长时间加工,出现“蠕变”或“应力松弛”现象,都会影响纺织品的形态或尺寸.特别是弹性纺织品,其力学性能不同于普通纤维.进行染整加工时,要注意纤维这些性能变化,特别在高温、高湿和存在对纤维有溶胀作用的化学品下加工时,更要严格控制加工温度、张力和处理时间.纺织品重复受到外力作用,则会由于连续发生蠕变,积累到一定程度后,将会发生疲劳破坏.弹性纤维纺织品由于弹性回复性好,一般不会出现疲劳破坏,但在较强的外力下长时间反复作用,也会损伤弹性.
为了不损伤弹性纤维的物理机械性能,特别是纺织品的弹性和尺寸稳定性,染整加工时应进行所谓松弛处理和热定形加工.
松弛处理的目的是消除纺织品,特别是其中的弹性纤维在纺丝、织造、运输、存放等过程中受到的残余内应力,使分子软链段充分卷曲松弛,达到稳定状态.此时纺织品的尺寸会发生一定程度的收缩,而其组织密度则会增加,从而使织物平整度提高,还可提高热定形效果,减少后续加工.例如精练和染色时形成折皱,改善产品手感和外观.松弛处理是在低张力、湿、热状态下进行的.当温度高于纤维的玻璃化温度后,无定形区主要是软链段区分子链运动加速,分子链调整到内应力很低的状态下后,弹性回复能力增强.分子链处在低内应力状态下后,纤维也不容易出现蠕变和应力松弛,更不会出现疲劳破坏现象.为了提高松弛处理效果,适当提高温度和含湿量可以加速纤维分子链的运动.松弛处理有多种方式,包括汽蒸松弛、热水松弛和干热松弛.如果有某些对纤维有溶胀作用的溶剂或助剂存在时,纤维分子链更加容易运动,可降低处理温度,即进行溶剂松弛处理.松弛处理通常和精练、染色和热定形等加工结合在一起进行,即在进行这些染整加工之前先在低张力下,于一定温度下低张力处理一定时间,然后进行精练、染色和热定形等加工.具体松弛处理的工序排列和条件随弹性纤维种类、纺织品组织结构和纺织品中其他纤维的性质而定,还要考虑纺织品中所含杂质的性质等因素.大多数情况是在热定形和精练前进行松弛处理,多半采用热水松弛处理,较少采用干热和溶剂松弛处理,一些情况下也可以采用热水和汽蒸结合的松弛处理.
热定形加工通常是将织物保持一定的尺寸,在较高温度下处理一定时间.其主要目的是提高织物的尺寸稳定性和消除皱痕,还可以改善织物的强力、手感和弹性,对某些纤维还可以改善染色性能.按纺织品加热时的含湿状态不同,热定形也可分干热和湿热定形2种工艺.水分存在可以降低定形温度,目前大多数工艺采用干热定形,对某些纺织品也可以进行蒸汽湿热定形.视纺织品所含纤维性能而定.
热定形温度比松弛处理高,必须高于纤维的玻璃化温度,但应低于纤维的软化温度,并且施加一定的张力,使织物拉伸到所需要的尺寸.在一定张力下使纤维分子链段(主要是软链段)朝拉伸方向蠕动,按外力作用的方向进行重排,此时会出现一定程度的应力松弛现象,分子链段在新的位置上建立结合,降温冷却后新建立的结构被固定下来.由于热定形温度高,且保持一定的张力,分子链段会发生较大的蠕动,纤维的超分子结构会发生明显变化.不同弹性纤维的分子链段结构和超分子结构不同.故热定形温度、张力和处理时间是不同的,热定形时超分子结构变化也是不同的.不过,目前对弹性纤维纺织品热定形的研究还很不够.对常规合成纤维(例如锦纶、 涤纶)来说,结晶度随热定形温度的提高会增高,因此热定形后纤维的形态稳定性会增高.一般认为,这是由于热定形的温度较高,热定形时一些结构完整性较差的晶体会熔化,完整性高的晶体则会增长和变得比较完整.由于弹性纤维具有软硬区段结构,无序结构更突出,热定形时结构变化将会更大,对温度和张力会更加敏感.所以弹性纺织品的热定形加工对其弹性等物理性能影响非常大,控制应更加严格.不同弹性纤维纺织品的热定形条件是不同的,而且由于弹性纤维在纺织品中的含量不同,所以热定形条件应根据弹性纤维结构、含量以及共混纤维的性质来确定.
弹性纤维纺织品的纺丝、织造加工条件不同于常规纤维纺织品,纤维上还施加了较多油剂等添加物,所以精练难度很大.
弹性纤维和其他纤维混纺或交织后,染色时都存在沾色问题，特别是分散染料对弹性纤维沾色较严重.因此,含弹性纤维的多组分纺织品,染色时要选用适当的防沾色剂,染后要加强洗涤,否则,色牢度特别是湿摩擦牢度较差.弹性纤维易沾色的原因主要有以下两点:(1)疏水性相对较强;(2)纤维无定形区含量较高,且纤维分子链间的孔隙较大,所以分散染料等较易吸附或沾染上纤维.不过沾染上的染料在水洗或摩擦时较容易脱落,即使是进入纤维内部的染料,也容易解吸扩散出来和洗除.
弹性纤维纺织品由于含有弹性纤维,它们的染整加工特性有别于常规纤维纺织品,染整加工特别要注意以下几点:(1)弹性纤维特别容易变形,弹性强,染整加工时应在低张力下进行.弹性纤维在一定的应力下容易产生蠕变,或在一定变形状态下容易发生应力松弛现象.发生变形和发生蠕变及应力松弛后,织物加工时容易出现门幅不齐、卷边、皱条等疵病,甚至在低张力下堆放也容易出现皱印或压条印.这些疵病会影响精练和染色的顺利进行.因此,弹性纤维纺织品染整加工时,不仅要低张力,而且打卷堆放要保持平整,染整加工前或加工中还要进行松弛处理和热定形加工;(2)弹性纤维纺织品所含油剂等添加物量多,特别是有机硅类润滑剂不易除去.所以精练时要选择专用精练剂,加强精练处理;(3)弹性纤维种类多,又多和其他纤维混纺或交织,染色时应仔细选用染料,并防止沾色,染后要加强洗涤;(4)和常规纤维相比,弹性纤维易变形,有的弹性纤维在较低温度下,其结晶体就会熔化,纤维变软,机械性能下降,所以弹性纤维纺织品染整加工应尽量在较低温度下进行,较适合运用低温精练、染色和洗涤工艺加工;(5)不同弹性纤维的弹性差异很大,它们在纺织品中的含量和分布也不尽相同.一些弹性纤维的弹性决定于纤维的形态结构,另一些决定于超分子结构,更多决定于硬链段和软链段的区段结构.这些起源于不同结构的弹性受温度、 应力和化学品作用影响是不同的,所以染整加工时应分别对待,以保持它们最佳的弹性结构状态.
弹性纺织品染整加工比常规纤维纺织品要求高.因此在制定染整工艺和控制工艺时要特别仔细,要求染整技术人员不仅掌握正常的加工技术,还要了解弹性纤维的化学和物理结构,特别是弹性和纤维结构的关系.由于弹性纤维品种发展很快,而对这类纺织品的染整加工经验又不多,故染整加工时更应仔细.
3·弹性纤维纺织品的染整加工工艺 弹性纤维纺织品穿着舒适,具有良好的保形性和抗皱性,应用日趋广泛,其品种已从针织向机织、从内衣向外衣、从女装向男装、从服用向家纺及医用等方面延伸,已成为当前主流纺织产品之一.目前,弹性纤维除了氨纶之外,出现了许多种新型弹性纤维.即使是氨纶,由于原料和纺丝工艺不同,其弹性等性能也不同.从弹性来讲,弹性纤维纺织品已逐渐形成高、中、低系列产品,它们的染整加工工艺要求不同.只有合理的加工工艺,才能保留或改善它们的弹性和服用性能.
目前应用较成熟的弹性纤维产品主要有氨纶(国外以Lycra商品为代表)、PTT纤维、PTT/PET纤维(以T-400为代表)、聚烯烃弹性纤维(以XLA弹性纤维为代表)等几种,它们分别与天然、化学纤维混纺或交织制成各种纺织品.
3.1氨纶(或Lycra)纺织品 氨纶除了少数情况下是以裸丝形态应用外,多半是以包芯纱、包覆纱、包缠纱和包捻纱形态应用.织物的弹性方向和程度取决于氨纶在织物中的含量和织造方式.机织面料中应用氨纶包覆纱和包芯纱后能提高其保形性,使服装更加舒适、时尚和贴身.目前国内生产的牛仔面料、衬衣面料不少都含有一定比例的氨纶,具有优良的弹性、尺寸稳定性和良好的吸湿透气性,受到消费者的喜爱.针织面料中应用氨纶的品种更多,大大提高了产品的质量和附加值.大多数情况下,氨纶是不专门进行染色的.从理论上讲,虽然氨纶也可以选用普通的分散染料染色.由于分散染料主要进入纤维内的软链段区,而软链段区的分子链不但长和柔顺,而且缺少与染料分子发生作用的极性基团;加上微隙较大,染料虽然容易扩散进去,也容易解吸和扩散出纤维,因此染色牢度差,且深染性差.为此国内外一直在研究如何改善氨纶的染色性能,主要途径有以下几方面:(1)开发或筛选适用的分散染料;(2)对纤维改性,在氨纶分子链上引入适当的基团,增强纤维与染料的结合能力.例如在分子链中引入氨基后,可使氨纶与酸性染料结合,使它和聚酰胺纤维一样用酸性染料染色;(3)改善染色条件,包括应用一些新的助剂,以提高氨纶的染色性能.
在改善氨纶染色性能方面笔者课题组做了一些研究开发工作[5-7],发现分散染料选用得当,氨纶用某些分散染料还是可以染得深色,色牢度也不错,分散染料结构和染色性能存在一定的关系;另外,选用一些助剂可以大大提高分散染料的染色性能,即进行分散染料助剂增溶染色.
含氨纶纤维纺织品染整加工的重要任务是染深色、提高色牢度和抗黄变.特别是近年来出现在市场上的高氨纶含量的超细锦纶混纺织品.由于具有多功能、多用途的服用性能,其产品的地位与日俱增,已生产成许多时尚风格的产品,但存在难染深、色牢度差和易泛黄的缺点[8],影响这些性能的主要因素有以下一些:(1)锦纶和氨纶纤维的类型及混纺比;(2)纺织品的组织结构;(3)染整加工的工艺条件(特别是前处理和染色);(4)染料和荧光增白剂的种类和性能;(5)染色用的固色剂及应用工艺条件;(6)后整理剂(柔软剂等)及应用工艺条件;(7)抗黄变剂的性能(高温或贮存时抗黄变性能);(8)加工设备特点.上述因素中纤维类型、染整加工条件、染料和荧光增白剂种类以及抗黄变剂的性能影响最为重要.
对染色深度来说,除了纤维和染料的类别和性能外,加工方式也影响很大.轧染由于上染时间短,染色深度一般不高.另外,由于氨纶染色性差,超细锦纶上染率虽然高,但深染性(即显色性)和色牢度差,也难染成坚牢的深色.另外这类产品的白度不高,这既和纤维粗细以及纤维混纺比有关,还和它们前处理难、易沾色有关.泛黄(即黄变)则和纤维、纤维上的油剂以及荧光增白剂、抗黄变剂的性能有关.为了提高白度和防止泛黄,应从前处理、染色清洗和选用适当的抗黄变剂多方面着手.
首先,染色前应充分前处理,尽量除尽纤维上的润滑剂、硅油等助剂.为此,合理选用具有高乳化效果的助剂非常重要,特别是对硅油有很强乳化能力的洗涤精练剂.
其次,防止泛黄,包括防止在高温加工时黄变和贮存时(较低温度,但时间长)黄变,应合理选用抗黄变剂.不同抗黄变剂的性能和功效是不同的.不同抗黄变剂处理工艺也是不同的,选用时可参看各种产品的应用技术说明.
产品泛黄和纺织品的酸碱性有密切关系,一般来说,在碱性条件下易泛黄,故加工时应选用还原性的有机酸(例如柠檬酸)来控制pH值,酸性也不能太强,尽量接近中性,从而避免穿着时对皮肤的刺激;加工时水中不能含有重金属离子,所以不仅要用软水,还要加入有较强络合能力的金属螯合剂;产品如果要进行压模整理,则需要进行抗热黄变整理,以防止产品在高温下黄变.
抗黄变剂多半是一些具有还原性的化学试剂.无论是纤维本身,还是其上面的油剂、荧光增白剂泛黄都和氧化作用有关,抗黄变剂抗黄变作用均随作用温度、时间和pH值等因素而不同.另外,它们对纤维的亲和力、吸附速率也不同,所以处理方式和条件各不相同.有些抗黄变剂,特别是对纤维亲和力较高的产品,可以采用浸渍方式处理;另一些则采用浸轧方式处理,浸轧后经过适当时间汽蒸,使抗黄变剂充分扩散进纤维内部,然后水洗,烘干即可.
此外,应提高产品颜色鲜艳度,这除了选用适当的染料外,采取合理的洗涤工艺也非常重要,所以染后水洗时先选用高效分散能力的净洗剂水洗,然后再进行固色处理.
锦纶/氨纶混纺织物目前仍主要选用高牢度的酸性染料染色,其中超细锦纶的色牢度不高.混纺织物中的氨纶虽然也可以吸附一些酸性染料,但上染率不高,而且色牢度差.因此,这种纺织品既染不深,色牢度又差.为了提高深染性,除了合理选用染料外,染色时选用适当的固色剂也很重要.固色剂有多种类型,固色机理也不同.从电性上分主要有阴离子类和阳离子类.阴离子类主要通过静电作用防止进入纤维内部的染料阴离子扩散出来,达到提高牢度的目的;阳离子类则主要通过与染料阴离子发生静电吸引起固色作用.它们可以分别应用,也可以前后一起联合应用.
近几年出现了一些新的氨纶品种,例如Xtra LifeLycra等.它们有的有很好的抗氯漂性能,有的有优良的保形性和弹性.此外还有一些含功能性微胶囊的氨纶,具有特种功能性.这些新的氨纶品种,染整加工性能往往不同于常规品种,应加以注意.
3.2 PTT纤维纺织品 PTT 纤维是一种新型聚酯纤维,模量较低,回复性较高,与氨纶相比易于加工,特别是易于染色,目前广泛用于制作“记忆面料”.PTT记忆面料不易折皱,折叠压皱后用手就可抚平,可塑性好,已广泛用于高档风衣、夹克衫和女性时装等.这种面料已从素色向色织、提花、印花、特色整理等多品种发展,不仅能染成各种颜色, 还可进行防水拒水、防皱、抗静电、易洗快干和免烫等多功能整理.但染整加工也会遇到不少问题,主要有以下几方面[9]:(1)染色时织物表面易出现色点和色雾;(2)染色易产生缸差;(3)易产生条花、白斑或色斑以及极光印痕;(4)由于纤维在湿热下易收缩,纺织品难染透.PTT纤维的玻璃化温度较低,熔点也比PET纤维低.因此,染色温度比PET纤维低,浅色品种甚至可在常温常压下用适当的分散染料染色.由于纤维模量较低,染整加工时纺织品对张力和机械摩擦作用较敏感,易变形和擦伤,纺织品表面易产生极光.出现这些疵病的原因主要是这种纤维受机械力作用时容易变形,而且容易出现“蠕变”和“应力松弛”现象.即使在较小应力下,纤维变形也随时间延长不断增加,或者在恒定的变形时,纤维内部应力会随时间延长而下降.这都表现在纤维内部结构或外形会随时间而变化,引起各种染整疵病,故要严格控制张力、温度和时间.和其他聚酯纤维一样,因含有较多的低聚物、PTT纺丝时还会粘附上较多的油剂等物质,也会使染整加工出现问题.因此,制定适当的染整工艺,合理选择染化料和助剂,并进行严格管理,才能得到高性能产品.
总的说来,PTT纤维纺织品染整加工重点要加强前处理,严格控制热定形和染整加工的张力,基本加工流程如下:坯布→(精练&碱减量)→预定形(130~140℃)→染色&R/C(100~120℃,40 min;60~80℃,20min)→防水/柔软处理→热定形(130~150℃)→检验.PTT弹性聚酯纤维染整加工时应特别仔细控制张力、温度和时间.张力过大(或机械摩擦、挤压力过强)容易使纤维发生过大变形或损伤,温度过高和处理时间过长也会使纤维变形过大.另外,它虽然化学稳定性较好,但仍然属聚酯纤维,碱性太强容易发生水解损伤.所以PTT纤维纺织品前处理温度为80~100℃,时间约为20 min,pH值为13左右.需选用PTT专用除油剂,它应能有效去除油脂和蜡质,还可以溶解低聚物.机织物宜采用平幅无张力或低张力处理,前处理时或之前应进行松弛处理.松弛处理可消除纤维的内应力,提高纺织品弹性,有利于后续加工.前处理要加强洗涤,除油剂应有良好的乳化能力.由于PTT

ABRASIVE TOOLS

NANTONG DONOR COMPANY LTD , https://www.ntdonglan.com