Textile Terms - Acrylic

Acrylic - concept

Pronunciation: jùbǐng xījīng xiān wéi

English name:polyacrylonitrile fiber

Polyacrylonitrile fiber is usually referred to as "acrylic"

Acrylic tube

Acrylic fiber is the trade name of polyacrylonitrile fiber in China, and it is known as "Alon" and "Cashmere" in foreign countries. Usually refers to a synthetic fiber obtained by wet spinning or dry spinning using a copolymer of 85% or more of acrylonitrile and second and third monomers. Fibers obtained by spinning a copolymer having an acrylonitrile content of 35% to 85% are called modified polyacrylonitrile fibers.

The performance of polyacrylonitrile fiber is very similar to that of wool, and the elasticity is good. When the elongation is 20%, the resilience rate can still maintain 65%. The fluffy is curled and soft, and the warmth is 15% higher than that of wool. It is called synthetic wool. Strength 22.1 ~ 48.5cN/dtex, 1 ~ 2.5 times higher than wool. Excellent sun-proof performance, open-air exposure for one year, strength only decreased by 20%, can be made into curtains, curtains, tarpaulins, gun Clothing and so on. Acid resistance, oxidant resistance and general organic solvents, but poor alkali resistance. Fiber softening temperature 190 ~ 230 °C.

Acrylic fiber is called artificial wool. With the advantages of softness, bulkiness, easy to dye, bright color, light resistance, antibacterial, and no fear of insects, it can be purely spun or blended with natural fiber according to the requirements of different uses. Its textiles are widely used in clothing, decoration, industry, etc. field.

Polyacrylonitrile fibers can be blended with wool into wool, or woven into carpets, carpets, etc., and can also be blended with cotton, man-made fibers, and other synthetic fibers to woven into a variety of clothing and interior products. Polyacrylonitrile fiber processing of the expanded tops can be purely spun, or blended with viscose fibers, wool, to get a variety of specifications in the coarse cashmere thread and fine cashmere "Cashmere."

Acrylic - Production Process

Polymerization → Spinning → Preheating → Steam Drafting → Washing → Drying → Heat Setting → Curling → Cutting → Packing.

Acrylic - Properties

The performance of polyacrylonitrile fiber is very similar to that of wool, and the elasticity is good. When the elongation is 20%, the resilience rate can still maintain 65%. The fluffy is curled and soft, and the warmth is 15% higher than that of wool. It is called synthetic wool. Strength 22.1 ~ 48.5cN/dtex, 1 ~ 2.5 times higher than wool. Excellent sun-proof performance, open-air exposure for one year, strength only decreased by 20%, can be made into curtains, curtains, tarpaulins, gun clothing and so on. Acid resistance, oxidant resistance and general organic solvents, but poor alkali resistance. Fiber softening temperature 190 ~ 230 °C.

Acrylic fiber is called artificial wool. With the advantages of softness, bulkiness, easy to dye, bright color, light resistance, antibacterial, and no fear of insects, it can be purely spun or blended with natural fiber according to the requirements of different uses. Its textiles are widely used in clothing, decoration, industry, etc. field.

Acrylic

Polyacrylonitrile fibers can be blended with wool into wool, or woven into carpets, carpets, etc., and can also be blended with cotton, man-made fibers, and other synthetic fibers to woven into a variety of clothing and interior products. Polyacrylonitrile fiber processing of the expanded tops can be purely spun, or blended with viscose fibers, wool, to get a variety of specifications in the coarse cashmere thread and fine cashmere "Cashmere."

Acrylic - The difference with other fibers

First, viscose (hygroscopic and easy to dye):

It is a man-made cellulose fiber, which is produced by solution spinning. Since the solidification rate of the fiber core layer is different from that of the outer layer, the skin core structure is formed (obviously seen from the cross-section slicing). Viscose is the most absorbent of ordinary chemical fiber, has good dyeability, good wearing comfort, poor visco-elasticity, weak wet strength, and poor abrasion resistance, so the viscose is not resistant to washing and has poor dimensional stability. Larger than the weight, fabric weight, alkali-resistant acid.

Viscose fiber is widely used, and almost all types of textiles will use it, such as filaments for lining, beautiful silk, flags, ribbons, tire cords, etc.; short fibers for imitation cotton, wool-like, blended, interwoven, etc.

Second, polyester (rigid not wrinkle):

Features: high strength, good impact resistance, heat resistance, corrosion resistance, resistance to rubbing, acid and alkali resistance, good light resistance (after acrylic), exposure to 1000 hours, strong maintenance of 60-70%, poor moisture absorption Difficult to dye, the fabric is easy to wash and dry, good shape retention. Has the "wash and wear" feature

use:

Filament: It is often used as a low elasticity yarn to make various kinds of textiles;

Staple fiber: cotton, wool, hemp, etc. can be blended, industrial: tire cords, fishing nets, ropes, filter cloth, border material. Is the largest amount of chemical fiber.

Third, nylon (strong wear resistance):

The biggest advantage is the strong wear resistance, which is the best one. Low density, light fabric, good elasticity, resistance to fatigue damage, chemical stability is also very good, alkali resistance is not acid!

The biggest disadvantage is that it is not able to resist sunlight, and the fabric will turn yellow when it is exposed to the sun for a long time. The strength is reduced and the moisture absorption is not good, but it is better than acrylic and polyester.

Uses: Filament, mostly used in knitting and silk industry; staple fiber, mostly blended with wool or wool chemical fiber, for Huada, Vandidine, etc. Industry: Cords and fishing nets, carpets, ropes, conveyors, screens, etc.

Acrylic products

Fourth, acrylic (bullish and fast):

Acrylic fiber is very similar to wool, so it is called "synthetic wool."

Molecular Structure: Acrylics are unique in their internal macroscopic structure and have an irregular spiral conformation. They do not have strict crystalline regions, but they have high and low order arrangements. Due to this structure, the acrylic fiber has very good thermal elasticity (processable bulked yarn), the acrylic fiber has a small density, is smaller than the wool, and the fabric has good thermal insulation properties.

Characteristics: Good resistance to sunlight and weather resistance (first place), poor moisture absorption, difficult dyeing.

Pure acrylonitrile fibers, due to the tight internal structure and poor handling properties, are improved by adding the second and third monomers, the second monomer improves: elasticity and feel, and the third monomer improves dyeability.

Uses: mainly for civilian use, can be pure spinning can also be blended, made of a variety of wool, wool, blankets, sportswear can also be: artificial fur, plush, expanded yarn, hose, parasol cloth and so on.

V. Vinyl (water-soluble moisture absorption):

The biggest feature is the high hygroscopicity, the best synthetic fiber, known as "synthetic cotton." The strength is worse than that of nylon and polyester, chemical stability is good, and it is not resistant to strong acid and alkali. The resistance to sunlight and weather is also very good, but it is resistant to dry heat and heat resistance (shrinkage), the worst elasticity, fabric wrinkles, poor dyeing, color is not bright.

Uses: multi-cotton blends: fine cloth, poplin, corduroy, underwear, canvas, tarpaulins, packaging materials, labor wear, etc.

Six, polypropylene (light and warmth):

Polypropylene fiber is the lightest fiber in common chemical fiber. It is almost non-hygroscopic, but has good wicking ability, high strength, dimensional stability, good abrasion resistance and good chemical stability. However: poor thermal stability, intolerance to the sun, easy to aging and crisp.

Uses: Can weave socks, mosquito net cloth, bedding, warm stuffing, wet diapers and so on. Industrial: carpets, fishing nets, canvases, hoses, medical belts instead of cotton gauze, and hygiene products.

Seven, spandex (elastic fiber):

The best elasticity, the worst strength, poor moisture absorption, better light, acid, alkali, wear resistance.

Uses: Spandex uses its characteristics are widely used in underwear, women's underwear, casual wear, sportswear, socks, pantyhose, bandages, mainly in the textile field, medical field and so on. Spandex is a highly elastic fiber required for the pursuit of dynamic and convenient high-performance clothing. Spandex can be stretched 5-7 times than the original, so it is comfortable to wear, soft to the touch, and does not wrinkle. It can always maintain its original contour.

Polyacrylonitrile was made as early as 100 years ago, but it was not made into fibers because there was no suitable solvent. In 1942, the German H. Rein and American G. H. Latham found dimethylformamide solvent almost simultaneously and succeeded in obtaining polyacrylonitrile fiber. In 1950, the United States DuPont first industrial production. Later, a variety of solvents were discovered and various production processes were formed. In 1954, the Bayer Company of the Federal Republic of Germany produced fibers with a copolymer of methyl acrylate and acrylonitrile, improved fiber properties, improved practicality, and promoted the development of polyacrylonitrile fibers. In 1984, the world production of polyacrylonitrile fibers was 2.4 Mt.

Acrylic - Production Method

The polyacrylonitrile fiber has high requirements on the purity of the raw material acrylonitrile, and the total content of various impurities should be less than 0.005%. The second monomer to be polymerized is mainly methyl acrylate, and methyl methacrylate may also be used for the purpose of improving the spinnability and the handfeel, softness and elasticity of the fiber; the third monomer is mainly to improve the dyeability of the fiber, generally Itaconic Acid Containing Weakly Acidic Staining Groups, Sodium Propyl Sulfonate, Sodium Methacrylate Sulfonate, Sodium Paramethacrylamide Benzene Sulfonate Containing Strongly Acidic Coloring Groups, -methyl Groups Containing Alkaline Staining Groups Vinyl pyridine and so on.

1 Polymerization The polymerization process is divided into two categories: suspension polymerization with water as the medium and solution polymerization with the solvent as the medium. The polymer obtained by suspension polymerization precipitated out in flocculent form, and was dissolved in a solvent to make a spinning solution. The solvent used in the solution polymerization can dissolve both the monomers and the polymers, and the resulting polymerization solution can be directly used for spinning. The solution polymerization solvent used is dimethylformamide, dimethyl sulfoxide, sodium thiocyanate, zinc chloride and the like. The polymerization time of the first two organic solvents is generally more than 10h, but the dissolving power is strong, the spinning solution concentration is higher, the spinning speed can be properly increased, the solvent recovery is also relatively simple, the obtained fiber has better performance, and the equipment Material requirements are lower; and with the latter two inorganic solvents, the polymerization time is only 2h, and the resulting fiber has better whiteness.

2 spinning spinning solution is generally polyacrylonitrile polymer, the number average molecular weight of 53000 ~ 106000, the fiber whiteness is better, the thermal decomposition temperature of 200 ~ 250 °C, the melting point of 320 °C. Therefore, polyacrylonitrile fibers are produced by wet spinning and dry spinning of a polymer solution. The dry spinning solution concentration is 25% to 30%, and the spinning speed is fast. However, due to the slow solidification of the spinneret, the spinneret sticks easily before curing. The spinneret with a large number of holes cannot be used. Only one kind of spinning solvent is dimethylformamide, and the resulting fiber structure is uniform and dense, and it is suitable for woven artificial silk fabrics. Wet spinning is suitable for producing short fibers, which are soft and fluffy, and suitable for weaving wool-like fabrics. In addition to the solvents used for solution polymerization, there are also dimethylacetamide, vinyl carbonate, **, etc. in the spinning solvent used. Most solvents have a high boiling point and are not easily distilled during spinning. In the 1980s, research was conducted on plasticizers made of polyacrylonitrile fibers with water as the polymer, eliminating the need to prepare polymer stocks, eliminating the need for solvent recovery and recycling systems, and the physical properties of fibers and dry or wet fibers. The fibers obtained by the method of spinning are basically the same and have now entered the intermediate test stage.

Modified varieties: Outstanding acrylonitrile and vinyl chloride copolymer fibers are copolymers obtained by copolymerizing acrylonitrile and vinyl chloride in acetone, and then obtained by dry spinning or wet spinning. In 1949, it was first produced by the U.S. Union Carbide Corporation. Since the content of vinyl chloride accounted for 50% to 60%, the flame retardant performance was good, and it had self-extinguishing properties, but the dyeability was slightly poor.

Acrylic - modified varieties

Outstanding acrylonitrile and vinyl chloride copolymer fibers are copolymers obtained by copolymerizing acrylonitrile and vinyl chloride and dissolved in acetone, and then obtained by dry spinning or wet spinning. In 1949, it was first produced by the U.S. Union Carbide Corporation. Since the content of vinyl chloride accounted for 50% to 60%, the flame retardant performance was good, and it had self-extinguishing properties, but the dyeability was slightly poor.

Acrylic-acrylic textile dyeing process

1. Dyeing process factors

(1) Effect of pH

The equilibrium dyeing amount increases with the increase of the pH value of the dye bath. Fibers containing weakly acidic groups can increase the dyeing base; the strong acidity is not obvious, and with the increase of pH value, the dye adsorption rate increases and it is not easy to level dye. The impact of carboxylic acid-containing acrylic fibers is even more pronounced. The effect of sulfonic acid-containing acrylic fibers on the dyeing rate is relatively small. The pH value is in the range of 4 to 6, and most of the dyes and fibers are stable. It is ideally between 4.5 and 5.5. In actual dyeing, a buffer system is used to keep the pH in the dye bath stable.

(2) Effect of temperature

Above the glass transition temperature, the dyeing rate will rapidly increase. When the dyeing temperature is 10-15°C above the glass transition temperature, most dyes will be dyed within this range. Therefore, the dye concentrates the dyeing area.

The stepwise temperature-staining dyeing, the closer to the concentrated dyeing area, the slower the heating rate should be, and each temperature rising period should be kept warm for a certain period of time to facilitate level dyeing. The highest dyeing temperature is generally controlled at 98 ~ 105 °C

The staining temperature had no significant effect on the saturation value of the dye.

(3) retarder

Improve the leveling properties of cationic dyes, can be divided into cationic, anionic, inorganic slow dyeing agent.

Cationic: fight for dyed seats and delay dyeing.

Anionic: An unstable dye-auxiliary complex is formed and gradually decomposes with increasing temperature.

Inorganic type: Weak acid, neutral salt (such as Yuan Mingfen), H+ inhibits the ionization of cellulose acidic groups,

The metal ion preferentially binds to the acidic groups on the fiber, delaying dye uptake.

2. Dyeing method

(1) The uniformity of the temperature of each part and proper heating rate at the time of dip dyeing are important for the leveling property of the product.

A. Temperature-control dyeing method

Use a more extensive and reliable dyeing process.

Strictly control the heating rate, slowly raise the temperature, and even perform stepwise temperature-rising dyeing. The dye liquor is well circulated, and the temperature and concentration uniformity of the various parts are maintained so that the dye is slowly dyed.

Use with a slowing agent.

B. Constant temperature dyeing

Avoid uneven temperature control and uneven dyeing caused by uneven dye bath temperature.

Choose a certain temperature above the glass transition temperature and below the boiling point of the dyeing liquid to start the dyeing process, keep it warm for 45-90 minutes, and then heat up to boiling for a short time.

Need to choose the appropriate temperature constant temperature dyeing, does not occur concentrated dyeing, evenly and slowly dyeing throughout the constant temperature stage.

(2) Continuous padding

Not widely used, mainly for blended or cross-fabric, and acrylic top or tow dyeing. [1]

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