What Is Polypropylene Sheeting?

Polypropylene fiber is a synthetic fiber spun from isotactic polypropylene obtained by the polymerization of propylene as a raw material. Its trade name in China is polypropylene.

Polypropylene fiber is a synthetic fiber spun from isotactic polypropylene obtained by the polymerization of propylene as a raw material. Its trade name in China is polypropylene.

Chinese name

Polypropylene fibers

Foreign name

polypropylene fiber

Monofilament fineness

2.2 dtex

Fiber length

1.5-200.0 mm

Classification of polypropylene fibers

Polypropylene fibers can be divided into long fibers, short fibers, spunbond nonwovens, meltblown nonwovens, and so on.

Polypropylene long fiber can be divided into ordinary long fiber and fine denier long fiber (monofilament fineness 2.2 dtex, which can be used to produce clothing and decoration and some industrial filament products. Polypropylene fine denier long fiber has good gloss, soft feel and drape Good performance and low density, suitable for knitting industry. When interwoven with cotton, viscose silk, silk, spandex and other products into cotton cover acrylic, silk cover acrylic and other products, it is an ideal material for making high-end sportswear and T-shirts.

The production process of polypropylene staple fiber mostly adopts a porous, low-speed, continuous process, that is, a short-spinning process. Polypropylene staple fibers are blended with cotton, which can be made into acrylic cotton muslins, sheets, that is, fibers and viscose blends can be used as blankets, polypropylene pure and blended yarns, polypropylene blankets, carpets, and polypropylene cotton smoke filters. The thickness of fibers for sanitary products is 1.5-2.5 dtex, while the thickness of fibers for ground fabrics is 5-10 dtex. The fiber length is 1.5-200.0 mm, depending on the use of the fiber. The length of short fibers used for concrete is 1.5-200.0 mm, the length used for diapers is generally 40.0 mm, and the length used for floor fabrics is 60.0 mm.

Spunbond non-woven fabric, also known as filament non-woven fabric, is made by melting polypropylene raw materials through extrusion spinning, stretching, laying, and bonding. It has the characteristics of short process, low cost, high productivity, excellent product performance, and wide range of uses. Polypropylene non-woven fabrics are widely used in various fields of production and life (such as disposable medical and sanitary products, disposable antifouling clothing, agricultural fabrics, furniture fabrics, linings for the shoe industry, etc.).

The fibers produced by the meltblown non-woven technology are very thin (up to 0.25 m). The meltblown cloth has a large specific surface area, small pores and large porosity, so its application characteristics such as filterability, shielding and oil absorption are Non-woven fabrics produced by other separate processes are difficult to have. Meltblown non-woven fabrics are widely used in medical and health, thermal insulation materials, filter materials and other fields.

A brief history of polypropylene fiber development

In the early days, propylene polymerization could only obtain paper products with a low degree of polymerization, which were non-crystalline compounds and had no practical value. In 1954, Ziegler and Natta invented the Ziegler-Natta catalyst and made it into crystalline polypropylene, which has high stereoregularity and is called isotactic polypropylene or isotactic polypropylene. This research achievement has opened up a new direction in the field of polymerization, laying the foundation for the large-scale industrial production of polypropylene and its extensive application in plastic products and fiber production.

In 1957, Montecatini of Italy first realized the industrial production of polypropylene. From 1958 to 1960, the company used polypropylene for fiber production and developed polypropylene fibers under the trade name Meraklon. Later, the United States and Canada also began production.

After 1964, it also developed polypropylene film split fibers for bundling, and made fibrillated films from textile fibrils and carpet yarns.

In the 1970s, short-range spinning processes and equipment improved the production process of polypropylene fibers. During the same period, bulk continuous filaments began to be used in the carpet industry. Currently, 90% of the carpet backing and 25% of the carpet veil worldwide are made of polypropylene fibers.

After 1980, with the development of polypropylene and new technologies for manufacturing polypropylene fibers, especially the invention of metallocene catalysts, the quality of polypropylene resins has been significantly improved. Due to the improvement of its stereoregularity (isotacticity can reach 99.5%), the inherent quality of polypropylene fibers is greatly improved. In the mid-1980s, polypropylene fine fibers replaced some cotton fibers for textile fabrics and nonwovens. Coupled with the development of one-step BCF spinning machines, air deformers and composite spinning machines, and the emergence and rapid development of nonwovens, the use of polypropylene fibers in decoration and industrial applications has been further expanded. In addition, the research and development of polypropylene fibers in various countries in the world are also very active. The popularity and improvement of differentiated fiber production technologies have greatly expanded the application fields of polypropylene fibers.

Performance characteristics of polypropylene fiber

(1) Lightweight

Polypropylene fiber has a density of 0.90-0.92 g / cm ^3. It is the lightest of all chemical fibers. It is 20% lighter than nylon, 30% lighter than polyester and 40% lighter than viscose fiber. Fabrics for skidding, mountaineering, etc.

(2) High strength, good elasticity, wear resistance and corrosion resistance

Polypropylene has high strength (same in dry and wet states) and is an ideal material for making fishing nets and cables. It has good abrasion resistance and resilience, similar in strength to polyester and nylon, and has a rebound rate comparable to nylon and wool. Polyester and viscose fibers are much larger; polypropylene has poor dimensional stability, is susceptible to pilling and deformation, is resistant to microorganisms, and is not stingy; chemical resistance is better than ordinary fibers.

(3) With electrical insulation and warmth

Polypropylene fiber has a high electrical resistivity (7 × 10 ¹⁹ .cm) and a small thermal conductivity. Compared with other chemical fibers, polypropylene has the best electrical insulation and warmth retention properties, but is prone to static electricity during processing.

(4) Poor heat and aging resistance

Polypropylene fiber has a low melting point (165-173 ° C) and poor stability to light and heat. Therefore, polypropylene has poor heat resistance and aging resistance, and is not resistant to ironing. However, anti-aging properties can be improved by adding anti-aging agents during spinning.

(5) Poor hygroscopicity and dyeability

Polypropylene fiber has the worst hygroscopicity and dyeability among chemical fibers, hardly hygroscopic, and its moisture regain is less than 0.03%. Fine denier polypropylene has a strong wicking effect, and water vapor can be eliminated through the capillary in the fiber. After the garment is made, the comfort of the garment is better, especially the ultra-fine polypropylene fiber, because of the increased surface area, it can transfer sweat faster and keep the skin comfortable. Because the fiber does not absorb moisture and has a small shrinkage rate, polypropylene fabric has the characteristics of easy washing and quick drying.

Polypropylene has poor dyeability, light color, and poor dyeing fastness. No ordinary fuel can be dyed, and most of the colored polypropylene is produced by spinning. Dope coloring, fiber modification, and fuel complexing agent can be blended before melt spinning.

Application fields of polypropylene fiber

(1) Industrial use

Polypropylene fiber has the advantages of high strength, good toughness, good chemical resistance, antimicrobial resistance, and low price, so it is widely used in ropes, fishing nets, safety belts, luggage belts, safety nets, sewing threads, cable covers, geotextiles , Filter cloth, papermaking felts and paper reinforcing materials.

Polypropylene woven geotextiles made of polypropylene fibers with high strength, acid resistance, alkali resistance, antimicrobial, and wet and dry strength can be used for civil engineering (such as dykes, reservoirs, highways) built on soft ground. , Railway, etc.) play a reinforcing role, and evenly distribute the load on the geotextile, so that the subgrade settlement is even, and the ground cracks are reduced. When constructing slopes, the use of woven polypropylene geotextiles can stabilize the slopes, reduce the collapse of the slopes, shorten the construction period, and extend the service life of the slopes. When carrying large loads, woven geotextiles and non-woven fabrics can be used as the matrix. Polypropylene fiber can be used as a filling material for concrete, plaster, etc., to improve the impact resistance, waterproof and heat insulation of concrete.

With the rapid development of the chemical industry, environmental protection and new energy industries, polypropylene fibers have good prospects for use as filter materials. New technologies make polypropylene fibers highly efficient, strong, lightweight, and stable to chemicals. The filter has good peelability. Therefore, in the pharmaceutical, chemical, environmental protection, battery and other industries as hydrophilic membranes, ion-exchange membranes and other functional products, they have a good momentum of development and are new high-tech products that increase the added value of polypropylene fibers.

(2) Decorative use

Polypropylene fiber has low density (only 65% of polyester fiber), light weight, strong covering power, good abrasion resistance, anti-microbial, insect-resistant, easy to clean, and is especially suitable for manufacturing decorative fabrics. Decorative fabrics such as carpets, sofa fabrics, and wall coverings made of polypropylene fiber, and cotton wool are not only cheap, but also have the advantages of resistance to stains, insects, easy washing, and good resilience.

The polypropylene fibers consumed in the field of decoration and daily use are mainly filaments, hollow short fibers and spunbonded nonwovens. The products are mainly automotive and household decorative materials, flakes, toys, etc.

(3) Clothing use

Because polypropylene fibers have a low melting point, are easy to wrinkle, and are not easy to dye, the application of polypropylene fibers in the field of clothing has been limited. With the development of spinning technology and the development of modified products, its application in the field of clothing is becoming wider and wider, and clothing products will be the hope of polypropylene development.

Polypropylene fiber can be made into knitwear, such as underwear, socks, etc .; can be made into plush products, such as shoe lining, coat lining, children's coat, etc .; can be blended with other fibers for children's clothing, work clothes, underwear, and Velvet fabrics and threads. For example, the development of fine and ultrafine polypropylene spinning technology has overcome the characteristics of rough, waxy, and poor hygroscopicity of ordinary polypropylene fibers. Fine special polypropylene fiber has soft, high strength and unique wicking effect. It is comfortable to wear, breathable and moisture-conducting. It can keep the skin dry when worn next to the skin. There is no moist feeling in summer and no cold feeling in winter. It is 2/5 lighter than cotton clothing, and its warmth is better than wool. It is the material of choice for sportswear, mountaineering clothing, military winter clothing and underwear. Pure polypropylene fabrics made of fine special polypropylene fibers, cotton-covered polypropylene and silk-covered polypropylene fabrics have been introduced to the market. Adidas sportswear is made of double-woven fabrics made of ultra-fine polypropylene fibers and cotton. . The United States uses fine special polypropylene filaments as raw materials to process military cold-proof fleece knitted underwear, and has been selected as the standard military equipment by the US Department of Defense.

(4) Non-woven fabric and medical polypropylene

Non-woven polypropylene fiber can be used in disposable sanitary products, such as sanitary napkins, surgical gowns, hats, masks, bedding, diaper fabrics, etc. Women's sanitary napkins, disposable babies and adult diapers have become common products for daily consumption. In addition, through chemical or physical modification of polypropylene fiber, it can have a variety of functions such as exchange, heat storage, conductivity, antibacterial, deodorization, ultraviolet shielding, adsorption, desquamation, isolation selection, and aggregation. It will become an artificial kidney, It is an important material in various medical fields such as artificial lungs, artificial blood vessels, surgical threads and liquid-absorbent gauze. Labor insurance clothing, disposable masks, hats, surgical gowns, quilt pillowcases, mattress materials, etc. all have growing markets.

(5) Other uses

Polypropylene tow can be used as cigarette filter filler. At present, more than half of the filters used in cigarettes of low and medium grades are made of polypropylene fibers.

Polypropylene fiber woven bags have widely replaced jute woven sacks, and have become the most important basic packaging materials for food, industrial raw materials, fertilizers, food, mineral sand and coal. The form has also been changed from the traditional pillow-type ladder. Diversified development such as barrel and column. Because of its low density, light weight, shape, and easy storage, it even replaced some small containers. There is a great demand for such products. Polypropylene non-woven fabrics are also widely used in the packaging field. For example, polypropylene non-woven fabrics manufactured by melt-blowing can be used in tea bags, insecticide bags, and slow-release packaging for special occasions.

Polypropylene fibers are also very suitable for the production of blankets. Brushed blankets are generally made of low-twist polypropylene fibers. This blanket has properties such as heat insulation, insect resistance, easy washing, low shrinkage and light weight, and is suitable for both domestic and military use.

Polyethylene film or plasticized polyvinyl chloride can be applied to polypropylene fiber fabrics by melt coating technology to produce protective cloth, windproof cloth and mine exhaust pipes. Polypropylene fiber fabrics coated with bitumen or tar can be used as a substrate for ponds, and other coated fabrics can be used as retaining drapes and temporary shelters.

Artificial turf is another application of polypropylene fibers. The American Biltret company uses polypropylene flat yarns to make a "single lawn" by looping. American Monsanto company also made suede artificial turf (called chemical grass) with polypropylene fiber. These artificial turf have been used in the central square of highways, transportation stations and other scenic areas. Polypropylene fiber has low sunlight resistance, so UV absorbers should be added in the production.

Polypropylene fiber has excellent acid and alkali resistance and good tensile strength. The canvas made with it is 1/3 lighter than ordinary canvas. It is used to make shoe lining cloth or sports shoe upper, which is strong and durable, lightweight, moisture-proof, breathable, and no sweaty.

Modification of polypropylene fibers and new varieties

Polypropylene fiber has many excellent properties, but also has the disadvantages of strong waxy feel, hard hand feel, difficult dyeing, and easy to accumulate static electricity. Therefore, modification of it and development of new varieties have become the main direction of polypropylene fiber development.

(1) Dyeable polypropylene fiber

Polypropylene fibers do not have fuel-friendly groups in the molecules, and the molecular aggregation structure is tight. Conventional polypropylene fibers are generally difficult to dye. At present, most of the polypropylene fibers on the market are obtained by coloring before spinning, but the color spectrum is incomplete and cannot be printed, which limits the variety of fabrics. Therefore, how to apply common dyeing techniques to polypropylene fibers has become a concern. At present, a variety of dyeable polypropylene fiber technologies have been developed. These technologies can be broadly divided into two categories: one is to graft a polymer or monomer containing a lipophilic group onto a polypropylene molecular chain through graft copolymerization, Make it dyeable; the second is to destroy and reduce the close aggregation structure of polypropylene macromolecules by blending spinning, so that polymers containing fuel-philic groups are mixed into polypropylene fibers, and some of the fibers have high interfaces. The sub-micro discontinuity of the energy enables the fuel to smoothly penetrate into the fiber and combine with the fuel-friendly groups.

(2) Industrial polypropylene filament and high-strength polypropylene fiber

Industrial polypropylene filament and high-strength polypropylene refers to all polypropylene filaments used in clothing. Its production process and use are obviously different from that of clothing fibers. By selecting high-molecular, high-specification polypropylene raw materials, starting from improving the degree of extension and crystallinity of macromolecular chains, and rationally controlling the spinning, stretching, and heat treatment processes, industrial polypropylene filaments or high-strength polypropylene fibers can be obtained. Its linear density, modulus, and strength requirements are high, and the requirements for elongation at break and elongation are generally low.

(3) Fine and ultrafine polypropylene fibers

Ordinary polypropylene fiber feels hard and has a waxy feel, so it is mainly used in carpets, non-woven fabrics, decorative fabrics, and industrial fabrics. The amount of clothing is very small. With the development of new catalysts and controllable rheological resin manufacturing technology, fine and ultra-fine polypropylene fibers have been rapidly developed, which has also laid the foundation for its application in the field of clothing.

The use of fine special polypropylene filaments as clothing materials has the characteristics of low density, low static electricity, warmth, good feel and special luster, resembles silk, etc., and has wicking effect, hydrophobicity, and moisture conductivity. It is used for making underwear and sportswear Ideal material.

(4) Flame retardant polypropylene fiber

Fabrics made of polypropylene fibers are flammable and accompanied by burning dripping, which limits its use. The flame retardant modification of polypropylene fiber is mainly prepared by adding modification and flame retardant finishing.

Polypropylene mainly uses halogen flame retardants and synergistic agents such as antimony trioxide to obtain flame retardant effects. Usually, high concentration flame retardants and other additives are first added to polypropylene chips, and the resistance is made by blending. Combustion masterbatches are then melt-spun with conventional polypropylene chip fibers to prepare flame-retardant polypropylene fibers. Phosphorus-bromine synergistic flame retardant system has good flame retardant effect for polypropylene fiber flame retardant, and has little environmental pollution, while phosphorus-nitrogen synergistic flame retardant system has better flame retardant effect for polypropylene fiber, but The application conditions in polypropylene fibers are relatively high.

(5) Far-infrared polypropylene fiber

Far-infrared polypropylene fiber is a new type of textile material with excellent health care and physiotherapy function, heat effect function, moisture-removing, breathable, and bacteriostatic function. It contains special ceramic components, which can absorb the radiant heat released by the human body, and emit the far-infrared rays with a wavelength of 4 to 14 m most needed by the human body after absorbing natural light and heat. This far-infrared ray has the characteristics of radiation, penetration and resonance absorption, is easily absorbed by human skin, activates tissue cells, promotes metabolism, and enables the body to achieve the health effects of moisturizing and promoting blood circulation.