In 1941, Whenfield and Dikson of the United Kingdom used terephthalic acid and ethylene glycol as raw materials to synthesize polyethylene terephthalate and made it into fibers. In China, the product name was polyester. Polyester was industrialized in the UK in 1946. It began to be industrialized on a large scale worldwide in 1953. In 1971, it began to exceed the number of nylons and became the largest synthetic fiber. Because polyester has excellent properties such as high strength, good elasticity, good shape retention and high dimensional stability, the woven fabric is durable and durable, has good electrical insulation, is easy to wash and dry, and has the reputation of “washable and wearableâ€. Therefore, it is widely used in clothing, decoration, industry and other fields. However, due to the close arrangement of internal molecules and the lack of a hydrophilic structure between the molecules, polyester has a low moisture regain and poor moisture absorption. Under the condition of relative humidity of 95%, the highest moisture absorption rate is 0.7%. Due to its poor hygroscopicity, the antistatic property is not good, the polyester fabric has poor gas permeability, poor dyeability and poor pilling resistance.
Research on polyester modification:
In view of the defects in the performance of polyester, the main researches on its modification are: physical modification method, physical blending modification in the production process of polyester; second, chemical modification method, using chemical grafting or block The method changes the molecular chain structure of polyester to improve the performance of polyester.
I. Dyeing Modification of Polyester Polyester fiber is a hydrophobic synthetic fiber lacking functional groups capable of combining with direct dyes, acid dyes, basic dyes and the like.
Although it has an ester group capable of forming a hydrogen bond with the disperse dye, the polyester molecular chain structure is tight, and the dye molecules are not easily entered into the fiber interior, resulting in difficulty in dyeing and monotonous color, which directly affects the development of polyester fabric color varieties. Due to the high crystallinity of polyester, there are only small gaps in the fiber. When the temperature is low, the thermal motion of the molecule changes its position to a small extent. Under humid conditions, the polyester fiber does not pass the violently like cotton fiber. Swelling increases the voids, and it is difficult for the dye molecules to penetrate into the inside of the fibers. Polyester dyeing can usually only be dyed with disperse dyes and must be dyed under high temperature and pressure or by means of a carrier. In order to improve the dyeing properties of polyester, from the molecular structure considerations, increasing the degree of looseness of the molecular chain will contribute to the entry of dye molecules. The main methods used to improve the dyeing performance are: (1) copolymerization with a bulky molecular compound; (2) mixing with a compound having a plasticizing effect; (3) introduction of an ether bond and a disperse dye pro And a good group. The polyester resin modified by the copolymerization method has a low melting point and a low crystallinity, and the thermal properties and mechanical properties of the fiber are damaged to some extent.
The cationic dye dyeing modification method is to copolymerize a polyester dyeing modifier, such as sodium phthalate-5-sulfonate (commonly known as three monomers, English abbreviation SIPM) with polyester, in the polyester molecular chain after copolymerization. Sulfonic acid groups are introduced, which can be dyed with cationic dyes. The dyed fabrics are brightly colored, the dye exhaustion rate is high, and the discharge of printing and dyeing wastewater is greatly reduced. The copolymerized polyester chips can also increase antistatic, anti-pilling and moisture absorption properties. It is one of the main methods to improve the dyeing performance of polyester in recent years. Japanese Unijika Company uses 4 parts of cationic dyeable polyester containing sulfonic acid group of isophthalate unit and 1 part of ethylene glycol / polyethylene glycol / sodium sulfonate isophthalate / para-benzene The block copolymer of dicarboxylic acid is blended and spun to form ultrafine fibers with high dyeing depth; before the spinning or during spinning, a cationic active agent and a small amount of a denaturant are copolymerized with BAET. When it is made into a random linear polymer, its spinnability becomes good. This modified polyester can be dyed not only with cationic dyes, but also with pilling resistance and improved wrinkle recovery.
In addition, while the cationic dyeable fiber is introduced. A modified polyester (PBT) with 1,4 butanediol instead of ethylene glycol as the second monomer has also joined the ranks of differentiated polyester. Replacing ethylene glycol with butanediol not only greatly increases the flexibility of the molecular chain, but also greatly improves the dyeing performance of the fiber to atmospheric pressure boiling. However, since the raw material price of 1,4-butanediol is much higher than that of ethylene glycol, PBT fiber lacks a competitive advantage in price. Therefore, at present, l,4 butanediol is mainly added as a third monomer in conventional PET, so that not only the price of the fiber is lowered, but also the dyeing property is improved, and the thermal stability is much better than that of the cationic dyeable fiber. .
Second, the anti-pilling modified polyester fabric of polyester is easy to pilling. It is closely related to fiber traits, mainly due to small cohesion between fibers, high fiber strength and high elongation ability, especially resistance to bending fatigue and torsion fatigue. With good wear resistance, the fiber easily slips out of the surface of the fabric, and once it forms a small ball on the surface, it is not easy to fall off. In the actual wearing and washing process. The fibers are constantly subjected to friction, exposing the fibers on the surface of the fabric to the fabric. There are many unpleasant furries on the surface of the fabric, that is, "pilling". If these furs do not fall off in time, they are entangled with each other and are smashed into many spherical granules, usually called pilling. The factors affecting fabric raising and pilling mainly include: (1) fibers constituting the fabric; (2) textile process parameters; (3) dyeing and finishing; and (4) taking conditions. The anti-pilling measures that have been used include: (1) reducing the molecular weight of the polyester, and reducing the rubbing fastness, bending fatigue resistance and strength of the fiber, so that the small ball formed on the surface of the fabric is relatively easy to fall off; (2) Change the shape of the fiber section. Shaped cross-section fibers, such as "T" or "Y", are easily broken when bent, and the fibers are entangled into clusters that are more difficult than round fibers; (3) reduce fiber elongation, increase staple length, and spun yarn The enthalpy effect, or the post-finishing process to obtain the anti-pilling effect, such as immersing the PET fiber in an alkali metal methanol solution at 180-240 ° C for treatment; (4) using the blending method to improve the pilling resistance, such as The l:1 cotton and PET blend produces anti-pilling fibers.
AKZO Nobel NV has developed a polyester fiber and yarn with high pilling resistance. The polyvinyl alcohol block copolymer is uniformly added to the polyester mixture as a separation phase during production. The specific polymer of the formulation contains at least 90% by mole of polyethylene terephthalate, and the polymer is polymerized. After the ester mixture is copolymerized, it is added in a weight ratio of 1% to 7%. When the polymer and the polyester mixture are uniformly mixed, a polyester fiber having anti-pilling properties can be obtained by a common spinning method.
Third, anti-static, anti-fouling and hygroscopic modified polyester Polyester Another serious shortcoming is poor water absorption, easy to be contaminated by oil, easy to carry static charge in low humidity. The antistatic fiber is produced by: (1) applying a durable antistatic agent to the fabric; (2) dispersing the heat resistant antistatic agent in the polyester melt, and spinning into a fabric; (3) The polyester molecular chain is copolymerized and modified, and the copolymer is melt-spun to improve the antistatic property of the polyester fiber. Commonly used reactive and soluble antistatic additives are glycol ethers and dicarboxylic acid amides and Schiff bases.
The antistatic property and the moisture absorption property of the high polymer fiber are improved, and a hydrophilic group is usually introduced into the polymer by copolymerization or the like to improve the moisture absorption property and reduce the specific resistance. For example, in the production process of PET, a suitable amount of polyethanol (PEG) is added, and a PET-PEG block copolymer is obtained by co-polycondensation, and is added as a modifier to the mixed spinning of PET to improve the polyester product. Antistatic and hygroscopic.
After the 1990s, Japan's Zhongfang, Teijin, Toray, and Kuraray have conducted research on conductive fibers. High-white conductive composite fiber developed by Toray Industries, Inc., developed a synthetic conjugate fiber composed of carbon black and thermoplastic elastomer with permanent electrical conductivity, and developed a white antistatic polyester for military uniforms and overalls. Filaments, fabrics woven therefrom not only have excellent antistatic properties, but also have excellent hand, dyeability, strength, washing resistance and chemical resistance. Developed by ICI Fiber, Epirtopic fiber is a unique conductive fiber. It is widely used. Its core is polyester. The skin layer is a copolymer of polyester and isophthalate. It is immersed in black carbon during production. In the grain.
The research on domestic conductive fiber started late. Zhejiang University, Zhejiang Metallurgical Research Institute and Hangzhou Peacock Chemical Fiber Group Co., Ltd. developed a plated composite conductive polyester. It uses ordinary PET as the substrate and is coated with a layer of polypropylene on its surface. Nitrile, then coated with polyacrylonitrile on the composite conductive Cu2S, made of conductive fibers with the same physical properties as ordinary PET, the fiber's electrical conductivity is durable, the resistance of 38 yarns spun from it can be less than 100Ω. Cm-1.
Conductive fibers are widely used, among which the earliest used in carpets, is currently the largest field, and other aspects are mainly used in anti-static, dust-removing overalls, general clothing and industrial materials. Antistatic dust-removing overalls are mainly used in the fields of dangerous goods such as oil and natural gas, semiconductors, electronics industry, precision instruments, medicine and health, etc. Their uses and markets are constantly expanding.
In recent years, domestic research and development of water-absorbing fibers, such as PBT/PET hollow microporous composite fiber developed by Beijing Fashion University, have shown excellent water absorption and water retention; Tianjin Petrochemical Company Polyester Factory and Beijing Fashion University jointly developed high water absorption Hollow polyester staple fiber can quickly absorb, transfer and release water, and spun high-absorbent staple fiber of nearly l0t 2.5dtex, and jointly develop high-absorbent fabric with textile manufacturers, and the sportswear has good wearing comfort; The water absorption rate of the highly absorbent polyester fiber successfully developed by Hua University is similar to that of cotton, which is 20.5%, and the moisture absorption rate is 2%, which is 5 times that of ordinary polyester. Teijin Company has a polyalkylene oxide with a weight average molecular weight of 100,000 or more inside the polyester fiber of 0.1% by weight to 15% by weight, and the polyalkylene glycol derivative is grafted on the surface of the fiber, which is hygroscopic and washable, and greatly improved. The hygroscopicity of polyester fibers.
Antistatic, antifouling and hygroscopicity are closely related to a certain extent. As long as the hydrophilicity of the polyester is improved, the three properties can be improved accordingly, and the polyester dyeing can be improved to some extent. performance.
Fourth, flame retardant modified polyester Polyester flame retardant modification has two methods of blending modification and copolymerization modification. Blending modification is to add flame retardant in the process of polyester chip synthesis to prepare flame retardant chips or to add flame retardant to polyester melt blending into flame retardant fiber during spinning; copolymerization modification is in synthetic polyester In the process, a copolymerized flame retardant is added as a monomer to prepare a flame retardant polyester by a copolymerization method.
The classification of flame retardant methods according to the production process can be summarized into the following five types:
(1) adding a reactive flame retardant at a transesterification or polycondensation stage for copolycondensation;
(2) adding an additive type flame retardant to the melt before melt spinning;
(3) composite spinning of ordinary polyester and polyester containing flame retardant component;
(4) graft copolymerizing with a reactive flame retardant on a polyester fiber or fabric;
(5) After the flame retardant treatment of the polyester fiber fabric.
There are many additive flame retardants that can be used for polyester fibers, and the addition of flame retardants is also the initial flame retardant modification method for polyester fibers. Flame retardants mainly include halogen flame retardants and phosphorus flame retardants. In the halogen flame retardant, the flame retardant effect of the bromine-based flame retardant is the best, and the synergistic effect with the quinone compound (such as antimony trioxide) can be combined to improve the flame retardant effect. Various flame retardants such as organic phosphates, inorganic phosphates and phosphorus oxides can be used for flame retardation modification of polyester fibers in phosphorus-based flame retardants. Among them, the aromatic phosphate ester has good thermal decomposition stability, and the addition to the polyester melt has little effect on the thermal degradation of the polyester, so that the spinning process and the fiber performance are not affected. At present, additive flame retardants have been widely used in some small polyester fiber manufacturers. The reactive flame retardant for polyester fibers refers to a small molecule flame retardant containing a flame retardant element (phosphorus, chlorine, bromine, fluorine) and a reactive group (carboxyl group, hydroxyl group, acid anhydride, etc.) in the molecule. The reactive flame retardant will gradually replace the added flame retardant. Usually a lower content (3% to 8%) of flame retardant is added to make the fiber have a good flame retardant effect. Reactive flame retardants which can be used for polyester fibers include halogen and phosphorus-based flame retardants. At present, the most commonly used in the world is a phosphorus-based copolymer flame retardant. Phosphorus-based flame retardants have good flame retardant effects on polyester fibers, and no toxic gases are formed during combustion. It is an environmentally friendly flame retardant system.
In the transesterification or polycondensation stage, a reactive flame retardant is added for copolycondensation, and since the copolymerized flame retardant monomer is fixed on the copolyester chain by a copolycondensation reaction to form a component on the macromolecular chain, the method is The influence of PET spinning performance is small, which represents the mainstream of the development of flame retardant polyester for fibers. For example, when synthesizing a flame retardant polyester, a polyester fiber section prepared by adding 4 wt% to 5 wt% of 2-carboxyethylphenylphosphinic acid (CEPPA) flame retardant can have an oxygen index of 32% to 33%; It has good activity and can obtain high molecular weight non-toxic and tasteless polyester chips with high thermal stability, oxidative stability and water resistance.
V. Prospect of polyester modification With the development of the synthetic fiber industry, the continuous improvement of people's living standards and the continuous advancement of science and technology, people's research on the modification of polyester fiber will be further developed, and the modified polyester fabric and The application of polyester blended fabrics will be more extensive, and the proportion of polyester for civil, decorative and industrial use will be further changed. The excellent properties of the polyester fabric itself, together with the bright color, good hand, pilling resistance and moisture absorption and antistatic property imparted by the modified fabric, will greatly promote the development of the polyester fiber industry.
Please indicate the source.
Unisex Running Shoes,Unisex Sports Shoes,Unisex Tennis Shoes,Unisex Football Boots
Huaying Shoes Co. Ltd , https://www.hyashoes.com