), their oxides (Si, Al or Zr), carbides (Si or B), nitrides (Al), etc., as well as from mixtures of these compounds, for example. dec. oxides or carbides. see also Glass fiber, Metal fibers, Asbestos.
Methods of obtaining: molding by a spunbond method from a melt; blowing the melt with hot inert gases or air, as well as in a centrifugal field (this method produces fibers from fusible silicates, for example, quartz and basalt, from metals and certain metal oxides); growing monocrystalline. melt fibers; molding from inorg. polymers with last. heat treatment (obtain oxide fibers); extrusion of plasticized polymers or fusible silicates of fine oxides with the last. their sintering; thermal processing org. (usually cellulose) fibers containing or other Comm. metals (obtain oxide and carbide fibers, and if the process is carried out in a reducing environment - metal); oxide fibers with carbon or the transformation of carbon fibers into carbide; gas-phase on a substrate - on filaments, strips of films (for example, boron and carbide fibers are obtained by deposition on a tungsten or carbon filament).
Mn. types of N. in. modify by applying surface (barrier) layers, Ch. arr. gas-phase deposition, which allows to increase their exploitation. sv-va (eg, with a carbide surface coating).
The majority of N. in. have polycrystalline structure, silicate fibers are usually amorphous. For N. century, received by gas-phase deposition, layer heterog is characteristic. structure, and for fibers obtained by sintering, the presence of a large number of . Fur. St. N. v. are given in the table. The more porous the structure of the fibers (for example, obtained by extrusion with afterbirth, sintering), the lower their density and fur. sv. N. in. stable in many aggressive media, non-hygroscopic. In oxidize. environment max. racks oxide fibers, to a lesser extent, carbide. Carbide fibers have semiconductor properties, their electrical conductivity increases with increasing t-ry.
MAIN PROPERTIES OF SOME TYPES OF HIGH STRENGTH INORGANIC FIBERS OF THE SPECIFIED COMPOSITION *
* Inorg. fibers used for thermal insulation and production of filter materials, have more than low fur. sv.
N. in. and reinforcing threads in constructive materials with org., ceramic. or metallic. matrix. N. in. (except for boron) are used to obtain fibrous or composite-fibrous (with inorganic or org. matrix) high-temperature porous heat insulators. materials; they can be operated for a long time at temperatures up to 1000-1500°C. From quartz and oxide N. to century. produce filters for aggressive liquids and hot gases. Electrically conductive silicon carbide fibers and threads are used in electrical engineering.
Lit.: Konkin A. A., Carbon into other heat-resistant fibrous materials, M., 1974; Kats S. M., High-temperature heat-insulating ma-
materials, M., 1981; Fillers for polymeric composite materials, lane. from English, M., 1981. K. E. Perepelkin.
Chemical encyclopedia. - M.: Soviet Encyclopedia. Ed. I. L. Knunyants. 1988 .
See what "INORGANIC FIBERS" is in other dictionaries:
They have inorg. main chains and do not contain org. side radicals. The main chains are built from covalent or ionic-covalent bonds; in some N. p., the chain of ion-covalent bonds can be interrupted by single joints of coordinates. character. ... ... Chemical Encyclopedia
Obtained from metals (eg Al, Cu, Au, Ag, Mo, W) and alloys (brass, steel, refractory, eg nichrome). They have polycrystalline structure (about M. v. single-crystal structures, see Whiskers). They produce fibers, monofilaments (thin wires) ... Chemical Encyclopedia
heat-resistant fibers- Synthetic fibers suitable for service in air at temperatures exceeding the thermal stability limits of conventional textile fibers. Obtained by molding from solutions of aromatic polyamides (see polyamide ... ... Textile glossary
Quartz fibers (filaments)- inorganic heat-resistant (high-temperature-resistant) fibers (threads) with high dielectric, acoustic, optical, chemical properties. These properties determine the wide application. K. N. in nuclear, aviation ... Encyclopedia of fashion and clothing
Materials inorganic- - materials from inanimate, inorganic nature: stone, ores, salts, etc. These materials are ubiquitous. They are non-combustible, used for the production of mineral binders, metals, aggregates in concrete, mineral fiber, etc. ... ... Encyclopedia of terms, definitions and explanations of building materials
Substances or materials that are introduced into polymer compositions. materials (e.g., plastic. masses, rubbers, adhesives, sealants, compounds, paints and varnishes) in order to modify the operational. st in, facilitating processing, as well as reducing them ... Chemical Encyclopedia
Polymer- (Polymer) Polymer Definition, Polymerization Types, Synthetic Polymers Polymer Definition Information, Polymerization Types, Synthetic Polymers Contents Contents Definition Historical Background Polymerization Science Types… … Encyclopedia of the investor
index- 01 GENERAL PROVISIONS. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION 01.020 Terminology (principles and coordination) 01.040 Dictionaries 01.040.01 General provisions. Terminology. Standardization. Documentation (Dictionaries) 01.040.03 Services. Organization of companies... International Organization for Standardization (ISO) standards
MUSCLES- MUSCLES. I. Histology. In general morphologically, the tissue of the contractile substance is characterized by the presence of specific differentiation in the protoplasm of its elements. fibrillar structure; the latter are spatially oriented in the direction of their contraction and ... ...
LEATHER- (integumentum commune), a complex organ that makes up the outer layer of the whole body and performs a number of functions, namely: protecting the body from harmful external influences, participating in thermoregulation and metabolism, and perceiving stimuli coming from outside. ... ... Big Medical Encyclopedia
Usage: for the manufacture of inorganic fibers soluble in physiological fluids. Described are inorganic fibers whose vacuum preforms have a shrinkage of 3.5% or less when exposed at 1260° C. for 24 hours. increase in shrinkage above 3.5%. The preferred range of fibers has a shrinkage of 3.5% or less when exposed at 1500°C for 24 hours and may contain, wt.%: SrO 53.2-57.6, Al 2 O 3 30.4-40.1, SiO 2 5.06-10.1. The technical task of the invention is to reduce the shrinkage of the workpiece. 2 s. and 15 z.p. f-ly, 4 tab.
The invention relates to artificial fibers from inorganic oxide. The invention also relates to products made from such fibers. Inorganic fibrous materials are well known and widely used for many purposes (for example, as thermal or acoustic insulation in bulk form, in the form of mats or sheets, in the form of vacuum-formed forms, in the form of vacuum-formed cardboard and paper, and in the form of ropes, yarn or textile; as a reinforcing fiber for building materials; as a constituent of vehicle brake pads). In most of these applications, the properties for which inorganic fibrous materials are used require resistance to heat and often resistance to harsh chemical environments. Inorganic fibrous materials may be either glassy or crystalline. Asbestos is an inorganic fibrous material, one form of which has been implicated in respiratory disease. It is still unclear what the causal mechanism is that links some types of asbestos to disease, but some researchers believe that the mechanism is mechanical and related to particle size. Critical particle size asbestos can enter cells in the body and thus, through prolonged and repeated cell damage, adversely affect health. Whether this mechanism is true or not, regulators have mandated that any inorganic fibrous product that has a respiratory fraction be classified as unhealthy, whether or not there is any evidence to support such a classification. Unfortunately, for many of the applications for which inorganic fibers are used, there are no viable substitutes. Thus, there is a need for inorganic fibers that will present the lowest possible hazard (if any) and for which there are objective reasons to consider them safe. One line of research has been proposed, which is that inorganic fibers would be made that are soluble enough in bodily fluids that their residence time in the human body is short; in this case, the damage would not have occurred, or at least would have been minimized. Since the risk of asbestos-related disease seems to depend very strongly on the duration of exposure to it, this idea seems reasonable. Asbestos is extremely insoluble. Since the interstitial fluid in nature is a saline (physiological) solution, the importance of dissolving the fibers in a saline solution has long been recognized. If the fibers are soluble in physiological saline, then, provided that the dissolved components are not toxic, the fibers should be safer than fibers that are insoluble. The shorter the residence time of a fiber in the body, the less damage it can cause. Such fibers are exemplified in the applicant's earlier International Patent Applications WO93/15028 and WO94/15883, which describe saline-soluble fibers used at temperatures of 1000°C and 1260°C, respectively. Another line of research suggests that hydrated fibers that lose their fibrous nature in body fluids may represent another route to "safe" fibers when the cause of damage is the shape and size of the fibers. This route is described in European Patent Applications N 0586797 and N 0585547, the purpose of which is to provide silica-free compositions and which describe two compositions of calcium aluminate (one containing 50/50 wt.% alumina/calcined lime, and the other containing 63 /30 wt.% alumina/calcined lime with the addition of 5% CaSO 4 and 2% other oxides). Such fibers hydrate easily, losing their fibrous nature. Asbestos does not hydrate and appears to retain its fibrous structure in body fluids effectively indefinitely. It has been found that strontium aluminate compositions do not appear to form fibers when meltblown products, while such compositions, including additives such as silica, do form fibers when meltblown. It appears that such fibers hydrate similarly to calcium aluminate fibers and further show potential for high temperature use. Vacuum-formed preforms (shapes) of some of these fibers show shrinkage of 3.5% or less when exposed to 1260° C. for 24 hours; some show shrinkage of 3.5% or less when exposed to 1400°C for 24 hours and some even show shrinkage of 3.5% or less when exposed to 1500°C for 24 hours. Such fibers provide hydrated high temperature fibers useful in the above products. Accordingly, this invention provides an inorganic fiber whose vacuum cast preform (shape) has a shrinkage of 3.5% or less when exposed at 1260 o C for 24 hours, a fiber containing SrO, Al 2 O 3 and a sufficient amount of fiber-forming additives for fiber formation, but not enough (not so much) to increase shrinkage above 3.5%. Preferably, the fiberizing additive contains SiO 2 and the constituents SrO, Al 2 O 3 and SiO 2 constitute at least 90 wt.% (more preferably at least 95 wt.%) of the fiber composition. The scope of the present invention is clearly defined in the appended claims with reference to the following description. In the following discussion, when a saline-soluble fiber is mentioned, it should be understood that it is a fiber having a total solubility of more than 10 ppm (ppm) in saline when measured by the method described below and, preferably, having higher solubility. The experimental results are described below with reference to tables 1, 2 and 3. Table 1 shows a number of compositions that were melted and blown by conventional methods. Those compositions indicated by "" did not fiberize to the desired extent, but did form a spherical powder. For each of these compositions, the analyzed composition is shown in wt. % (obtained by X-ray fluorescence analysis). If a number is given<0,05", это означает, что соответствующий компонент не мог быть обнаружен. Благодаря природе рентгеновских флуоресцентных измерений (которые чувствительны к окружающей среде) общее количество материала, обнаруживаемого этим анализом, может доходить до 100% или превышать 100%, и в данной патентной заявке (в том числе в описании, формуле изобретения и реферате) эти числа не были нормализованы до 100%. Однако для каждой композиции указывается общее количество анализируемого материала и можно видеть, что отклонение от 100% является небольшим. В столбце, названном "Относительный мас. процент", указаны мас. % SrO, Al 2 O 3 и SiO 2 по отношению к сумме этих компонентов. За исключением случаев, когда контекст дает иные указания, любые проценты, указанные в данной заявке, являются процентами, полученными рентгеновским флуоресцентным анализом, а не абсолютными процентами. Таблица 2 показывает (в том же порядке, что и в Таблице 1) данные усадки и растворимости для волокнообразующих композиций. Растворимость выражена как части на млн. В растворе, как измерено описанным ниже способом. Все указанные выше композиции и включая линию A Таблиц 1 и 2 включительно содержат 2,76 мас.% или менее SiO 2 . Можно видеть, что большинство этих композиций не образовывали волокна. Некоторые из этих волокон включают в себя Na 2 O в количествах 2,46 мас.% или более для содействия образованию волокна, но обнаруживают плохие характеристики усадки при температурах более 1000 o C (т.е. имеют усадку более 3,5% при измеренной температуре). Одно волокно (SA5 (2,5% K 2 O/SiO 2)), содержащее 1,96% K 2 O и 2,69% SiO 2 , имеет приемлемую усадку при 1260 o C. Таким образом, можно видеть, что "чистые" алюминаты стронция не образуют волокон, тогда как посредством добавления волокнообразующих добавок, например, SiO 2 и Na 2 O, могут быть образованы волокна. Характеристики усадки полученных волокон зависят от примененных добавок. Волокна, представленные ниже линии A и выше и включая линию В, имеют содержание SrO менее 35 мас.% и имеют плохие характеристики усадки. Волокна, показанные ниже линии В, имеют содержание SrO более 35 мас.% и, в случае измерения, обнаруживают приемлемую усадку при 1260 o C. Волокно линии С содержит 2,52 мас.% CaO и это, по-видимому, вредит характеристикам при 1400 o C. Волокна, представленные ниже линии D и выше и на линии E, имеют содержание Al 2 O 3 более 48,8 мас.%, что, по-видимому, неблагоприятно влияет на характеристики волокон при 1400 o C. Волокно ниже линии E имеет содержание SiO 2 14,9 мас.%, что, по-видимому, плохо для характеристик при 1400 o C (см. ниже для показателя при 1500 o C). Дальнейший ограниченный диапазон композиций (показанных жирным текстом в столбце 1400 o C) проявляет тенденцию к приемлемой усадке при 1400 o C. Эти композиции лежат ниже линии C и выше и на линии D Таблиц 1 и 2. Два волокна, указанных в этом диапазоне, которые не удовлетворяют требованию усадки 3,5%, могут быть просто неправильными результатами. Волокна, лежащие ниже линии C и выше линии D и на линии D, были отобраны по относительному мас.% SrO (как определено выше), и можно видеть, что композиции с относительным мас.% SrO, большим, чем 53,7%, и меньшим, чем 59,6%, имеют тенденцию к приемлемым усадкам при 1500 o C. Волокно в этой области, которое не имеет приемлемой усадки при 1500 o C, является волокном с высоким содержанием SiO 2 (12,2 мас.% SiO 2), что подтверждает неблагоприятное действие слишком большого содержания SiO 2 упомянутое выше. Два волокна (SA5a и SA5aII) обнаруживают приемлемую усадку при 1550 o C. Кроме того, можно видеть, что некоторые из этих волокон проявляют очень высокие растворимости и, таким образом, могут обеспечивать применимые трудно перерабатываемые (устойчивые) волокна, которые будут растворяться в жидкостях тела. Все волокна показали гидратацию при введении в водные жидкости. Действительно, они имели тенденцию к некоторой гидратации при образовании предварительных заготовок, которые были использованы для испытания усадки. После 24 часов испытания растворимости в жидкостях физиологического типа гидратация была очень явной. Гидратация имеет форму видимого растворения и переосаждения кристаллов на поверхности волокон, что приводит к потере их волокнистой природы. Для некоторых из композиций при изготовлении вакуумных предварительных заготовок для испытаний использовали диспергирующий и смачивающий агент (Troy EX 516-2 (Trade markof Troy Chemical Corporation)), который является смесью неионогенных поверхностно-активных веществ и химически модифицированных жирных кислот. Это было попыткой уменьшить время экспонирования с водой и, следовательно, степени гидратации. Из таблицы 3 можно видеть (Таблица 3 показывает тот же тип информации, что и Таблица 2), что композиции, в которых использовали диспергирующий агент (указанный как "troy"), имели тенденцию к более высокой усадке, чем идентичная композиция без диспергирующего агента. Предполагается, что это может быть обусловлено частичным гидратационным "смыканием" волокон вместе, так что любое отдельное волокно должно иметь усадку против растяжения поддерживающих волокон вдоль его длины: такое растяжение может приводить к утончению волокна скорее, чем к продольной усадке. В случае использования диспергирующего агента волокна свободны для усадки вдоль их длины. Далее подробно описаны способы измерения усадки и растворимости. Усадку измеряли посредством предложенного ISO стандарта ISO/TC33/SC2/N220 (эквивалент British Standard BS 1920, part 6.1986) с некоторыми модификациями с учетом малого размера образцов. Способ в кратком изложении содержит изготовление вакуумно отлитых предварительных заготовок, с использованием 75 г волокна в 500 куб. см 0,2% раствора крахмала, в приспособлении 120х65 мм. Платиновые штифты (приблизительно 0,5 мм в диаметре) помещали отдельно в 4 углах в виде прямоугольника 100х45 мм. Самые большие длины (L1 и L2) и диагонали (L3 и L4) измеряли с точностью 1 5 мкм, используя передвижной микроскоп. Образцы помещали в печь и доводили до температуры на 50 o C ниже температуры испытания при скорости 300 o C/час и при скорости 120 o C/час для последних 50 o C до температуры испытания и оставляли в течение 24 часов. Величины усадки даны в виде среднего из 4 измерений. Следует отметить, что хотя это стандартный способ измерения усадки волокна, он имеет присущую ему изменчивость, заключающуюся в том, что конечная плотность предварительной заготовки может меняться в зависимости от условий отливки. Кроме того, следует отметить, что волоконный материал будет обычно иметь более высокую усадку, чем предварительная заготовка, изготовленная из того же самого волокна. Поэтому цифру 3,5%, упоминаемую в данной заявке, следует толковать как более высокую усадку в конечном полотне из этого волокна. Растворимость измеряли согласно следующему способу. Волокно сначала нарезали с использованием сита 10 меш. и сферический порошок удаляли ручным просеиванием также через сито 10 меш. Устройство для испытания растворимости содержало вибрационную термостатную водяную баню и раствор для испытаний имел состав, приведенный в табл. 4. Вышеуказанные вещества разбавляли до 1 литра дистиллированной водой для образования солевого раствора, подобного физиологическому раствору. 0,500 г, "равных" 0,003 г нарезанного волокна, взвешивали в пластиковую пробирку центрифуги и добавляли 25 мл (см 3) указанного выше солевого раствора. Волокно и солевой раствор встряхивали тщательно и вводили в вибрационную термостатную водяную баню, поддерживаемую при температуре тела (37 o C 1 o C). Скорость вибратора устанавливали при 20 оборотов/мин. После 24 часов пробирку центрифуги удаляли, всплывающую жидкость декантировали и жидкость пропускали через фильтр (мембрана из фильтровальной бумаги из нитрата целлюлозы 0,45 микрон [типа WCN из Whatman Labsales Limited]) в прозрачный пластиковый флакон. Затем жидкость анализировали одним из двух способов. Первым используемым способом было атомное поглощение с применением машины Thermo Jarrell Ash Smith - Hiefje II. Условия работы были такие же, какие установлены в более ранних Международных Патентных заявках заявителя WO93,15028 и WO 94/15883. Для SrO условия работы были следующими:
WAVE LENGTH (nm) 460.7
BAND WIDTH, 0
CURRENT, (mA) 12
FLAME, lean fuel
Strontium was measured against a standard solution for atomic absorption (Aldrich 970 μm/ml). Three standards were prepared to which 0.1% KCl was added (Sr [ppm] 9.7, 3.9 and 1.9). Typically, 10- and 20-fold dilutions were prepared to measure the Sr level in the sample. SrO was then calculated as 1.183xSr. All stock solutions were stored in plastic bottles. In the second method used (which was shown to give results consistent with those of the first method), element concentrations were determined using inductively coupled plasma-atomic emission spectroscopy in accordance with a known method. The above has made it possible to discuss the shrinkage resistance of preforms exposed to 1260° C. for 24 hours. This is the maximum fiber usage temperature. In practice, fibers are characterized by a maximum continuous use temperature and a higher maximum exposure temperature. Typically in the industry, when selecting a fiber for use at a given temperature, a fiber is selected that has a higher continuous use temperature than the temperature nominally required for the intended use. This is to ensure that any accidental increase in temperature does not damage the fibers. A difference of 100-150 o C is quite common. Applicants have not yet determined what amount of other oxides or other impurities will affect the characteristics of the fibers described above, and the attached claims allow, in case the fiber-forming additive is SiO 2, up to 10 wt .% materials other than SrO, Al 2 O 3 and SiO 2 although this should not be considered as a limitation. Although the above description refers to the manufacture of fibers by melt blowing, this invention is not limited to blowing, but also covers drawing and other methods (technologies) in which fibers are formed from the melt, and also includes fibers made by any other method.
CLAIM
1. Inorganic fiber containing SrO and Al 2 O 3 , characterized in that the vacuum fiber preform has a shrinkage of 3.5% or less when held at 1260 o C for 24 hours and the fiber has a composition of strontium aluminate, including SrO, Al 2 O 3 and a fiberizing additive sufficient to form a fiber, but not so large as to increase the shrinkage above 3.5% and in the case where SiO 2 is present, the amount of SiO 2 is less than 14.9 wt.%. 2. An inorganic fiber according to claim 1, characterized in that the fiber-forming additive contains SiO 2 and the constituents SrO, Al 2 O 3 and SiO 2 constitute at least 90 wt.% of the composition of the fiber. 3. Inorganic fiber according to claim 2, characterized in that the constituents SrO, Al 2 O 3 and SiO 2 constitute at least 95 wt.% of the composition of the fiber. 4. An inorganic fiber according to any one of the preceding claims, characterized in that it contains 35% by weight or more of SrO. 5. Inorganic fiber according to any of the preceding claims, characterized in that it contains SrO 41.2 - 63.8 wt.% and Al 2 O 3 29.9 - 53.1 wt.%. 6. Inorganic fiber according to claim 5, characterized in that it contains more than 2.76 wt.% SiO 2 . 7. Inorganic fiber according to any one of the preceding claims, characterized in that the vacuum preform has a shrinkage of 3.5% or less when held at 1400°C for 24 hours. 8. Inorganic fiber according to claim 7, characterized in that the amount of Al 2 O 3 is 48.8 mass% or less. 9. Inorganic fiber according to any of the preceding claims, characterized in that the vacuum preform has a shrinkage of 3.5% or less when held at 1500 o C for 24 hours. 10. Inorganic fiber according to claim 9, characterized in that the mass% SrO relative to the total amount of SrO plus Al 2 O 3 plus SiO 2 is in the range from more than 53.7 wt.% to less than 59.6 wt.%. 11. Inorganic fiber according to claim 10, characterized in that it contains, wt. %:SrO - 53.2 - 57.6
Al 2 O 3 - 30.4 - 40.1
SiO 2 - 5.06 - 10.1
12. An inorganic fiber according to any one of the preceding claims, characterized in that it contains Na 2 O in an amount of less than 2.46% by weight. 13. An inorganic fiber according to any one of the preceding claims, characterized in that the vacuum preform has a shrinkage of 3.5% or less when held at 1550° C. for 24 hours. wt. %:
SrO - 53.2 - 54.9
Al 2 O 3 - 39.9 - 40.1
SiO 2 - 5.06 - 5.34
15. An inorganic fiber according to any one of the preceding claims, characterized in that it is a saline-soluble fiber. 16. An inorganic fiber according to any one of the preceding claims, characterized in that it is a hydrated, saline-soluble fiber. 17. Method for producing fibers from a melt, characterized in that the melt contains predominantly SrO and Al 2 O 3 , to which small amounts of SiO 2 are added to form fibers.
In addition to those already listed, there are fibers from natural inorganic compounds. They are divided into natural and chemical.
Asbestos, a fine-fibrous silicate mineral, belongs to natural inorganic fibers. Asbestos fibers are fire-resistant (the melting point of asbestos reaches 1500 ° C), alkali- and acid-resistant, non-heat-conducting.
The elementary fibers of asbestos are combined into technical fibers, which serve as the basis for threads used for technical purposes and in the development of fabrics for special clothing that can withstand high temperatures and open fire.
Chemical inorganic fibers are divided into glass fibers (silicon) and metal-containing.
Silicon fibers, or glass fibers, are made from molten glass in the form of elementary fibers with a diameter of 3-100 microns and very long lengths. In addition to them, staple fiberglass is produced with a diameter of 0.1-20 microns and a length of 10-500 mm. Fiberglass is non-combustible, chemically resistant, has electrical, heat and sound insulation properties. It is used for the manufacture of tapes, fabrics, nets, non-woven fabrics, fibrous canvases, cotton wool for technical needs in various sectors of the country's economy.
Metallic artificial fibers are produced in the form of threads by gradually drawing (drawing) a metal wire. This is how copper, steel, silver, gold threads are obtained. Aluminum filaments are made by cutting a flat aluminum strip (foil) into thin strips. Metal threads can be given different colors by applying colored varnishes to them. To give greater strength to metal threads, they are wrapped with threads of silk or cotton. When the threads are covered with a thin protective synthetic film, transparent or colored, combined metal threads are obtained - metlon, lurex, alunit.
The following types of metal threads are produced: rounded metal thread; flat thread in the form of a ribbon - flattened; twisted thread - tinsel; flattened, twisted with silk or cotton thread - stranded.
The 19th century was marked by important discoveries in science and technology. A sharp technical boom affected almost all areas of production, many processes were automated and moved to a qualitatively new level. The technical revolution did not bypass the textile industry either - in 1890, a fiber made using chemical reactions was first obtained in France. The history of chemical fibers began with this event.
Types, classification and properties of chemical fibers
According to the classification, all fibers are divided into two main groups: organic and inorganic. Organic fibers include artificial and synthetic fibers. The difference between them is that artificial ones are created from natural materials (polymers), but with the help of chemical reactions. Synthetic fibers use synthetic polymers as raw materials, while the processes for obtaining fabrics are not fundamentally different. Inorganic fibers include a group of mineral fibers that are obtained from inorganic raw materials.
Hydrated cellulose, cellulose acetate and protein polymers are used as raw materials for artificial fibers, and carbochain and heterochain polymers are used for synthetic fibers.
Due to the fact that chemical processes are used in the production of chemical fibers, the properties of the fibers, primarily mechanical, can be changed using different parameters of the production process.
The main distinguishing properties of chemical fibers, in comparison with natural ones, are:
- high strength;
- the ability to stretch;
- tensile strength and long-term loads of different strengths;
- resistance to light, moisture, bacteria;
- crease resistance.
Some special types are resistant to high temperatures and aggressive environments.
GOST chemical threads
According to the All-Russian GOST, the classification of chemical fibers is quite complicated.
Artificial fibers and threads, according to GOST, are divided into:
- artificial fibers;
- artificial threads for cord fabric;
- artificial threads for technical products;
- technical threads for twine;
- artificial textile threads.
Synthetic fibers and threads, in turn, consist of the following groups: synthetic fibers, synthetic threads for cord fabric, for technical products, film and textile synthetic threads.
Each group includes one or more subspecies. Each subspecies has its own code in the catalog.
Technology of obtaining, production of chemical fibers
The production of chemical fibers has great advantages over natural fibers:
- firstly, their production does not depend on the season;
- secondly, the production process itself, although quite complicated, is much less laborious;
- thirdly, it is an opportunity to obtain a fiber with pre-set parameters.
From a technological point of view, these processes are complex and always consist of several stages. First, the raw material is obtained, then it is converted into a special spinning solution, then the fibers are formed and finished.
Various techniques are used to form fibers:
- use of wet, dry or dry-wet mortar;
- application of metal foil cutting;
- drawing from a melt or dispersion;
- drawing;
- flattening;
- gel molding.
Application of chemical fibers
Chemical fibers have a very wide application in many industries. Their main advantage is relatively low cost and long service life. Fabrics made from chemical fibers are actively used for tailoring special clothes, in the automotive industry - for strengthening tires. In the technique of various kinds, non-woven materials made of synthetic or mineral fibers are more often used.
Textile chemical fibers
Gaseous products of oil and coal processing are used as raw materials for the production of textile fibers of chemical origin (in particular, for the production of synthetic fibers). Thus, fibers are synthesized that differ in composition, properties and combustion method.
Among the most popular:
- polyester fibers (lavsan, krimplen);
- polyamide fibers (nylon, nylon);
- polyacrylonitrile fibers (nitron, acrylic);
- elastane fiber (lycra, dorlastan).
Among the artificial fibers, the most common are viscose and acetate. Viscose fibers are obtained from cellulose - mainly spruce. Through chemical processes, this fiber can be given a visual resemblance to natural silk, wool or cotton. Acetate fiber is made from waste from cotton production, so they absorb moisture well.
Chemical fiber nonwovens
Nonwoven materials can be obtained from both natural and chemical fibers. Often non-woven materials are produced from recycled materials and waste from other industries.
The fibrous base, prepared by mechanical, aerodynamic, hydraulic, electrostatic or fiber-forming methods, is fastened.
The main stage in the production of nonwoven materials is the stage of bonding the fibrous base, obtained by one of the following methods:
- Chemical or adhesive (adhesive)- the formed web is impregnated, coated or irrigated with a binder component in the form of an aqueous solution, the application of which can be continuous or fragmented.
- Thermal- this method uses the thermoplastic properties of some synthetic fibers. Sometimes the fibers that make up the nonwoven material are used, but in most cases a small amount of fibers with a low melting point (bicomponent) is deliberately added to the nonwoven material at the spinning stage.
Chemical fiber industry facilities
Since chemical production covers several areas of industry, all chemical industry facilities are divided into 5 classes depending on the raw materials and applications:
- organic matter;
- inorganic substances;
- organic synthesis materials;
- pure substances and chemicals;
- pharmaceutical and medical group.
According to the type of purpose, chemical fiber industry facilities are divided into main, general factory and auxiliary.
Author Chemical Encyclopedia b.b. I.L.KnunyantsINORGANIC FIBERS, fibrous materials obtained from certain elements (B, metals), their oxides (Si, Al or Zr), carbides (Si or B), nitrides (Al), etc., as well as from mixtures of these compounds, for example, various oxides or carbides. See also Glass fiber, Metal fibers, Asbestos.
Methods of obtaining: molding by a spunbond method from a melt; blowing the melt with hot inert gases or air, as well as in a centrifugal field (this method produces fibers from fusible silicates, such as quartz and basalt, from metals and some metal oxides); growing monocrystalline. melt fibers; spinning from inorganic polymers followed by heat treatment (oxide fibers are obtained); extrusion of finely dispersed oxides plasticized with polymers or fusible silicates, followed by their sintering; thermodynamic processing of organic (usually cellulose) fibers containing salts or other metal compounds (oxide and carbide fibers are obtained, and if the process is carried out in a reducing medium, metal); reduction of oxide fibers with carbon or the transformation of carbon fibers into carbide; gas-phase deposition on a substrate - on filaments, strips of films (for example, boron and carbide fibers are obtained by deposition on a tungsten or carbon filament).
Mn. types of INORGANIC FIBERS c. modified by applying surface (barrier) layers, mainly gas-phase deposition, which improves their performance properties (for example, carbon fibers with a carbide surface coating).
TO INORGANIC FIBERSv. needle-shaped single crystals of various compounds are close (see Filamentous crystals).
Most of the INORGANIC FIBERS in. have polycrystalline structure, silicate fibers are usually amorphous. For INORGANIC FIBERS, obtained by gas-phase deposition, a layered heterogeneity is characteristic. structure, and for fibers obtained by sintering, the presence of a large number of holes. Fur. properties INORGANIC FIBERS c. are given in the table. The more porous the structure of the fibers (for example, obtained by extrusion with afterbirth, sintering), the lower their density and mechanical properties. INORGANIC FIBERS stable in many aggressive environments, non-hygroscopic. In oxidize. In the environment, oxide fibers are the most resistant, and carbide fibers are to a lesser extent. Carbide fibers have semiconductor properties, their electrical conductivity increases with increasing temperature.
MAIN PROPERTIES OF SOME TYPES OF HIGH STRENGTH INORGANIC FIBERS OF THE SPECIFIED COMPOSITION *
* Inorganic fiber used for thermal insulation and production of filter materials, have more than low mechanical properties.
INORGANIC FIBERS and thread-reinforcing fillers in the design. materials with organic, ceramic. or metallic. matrix. INORGANIC FIBERS (except for boron) are used to obtain fibrous or composite-fibrous (with an inorganic or organic matrix) high-temperature porous heat insulators. materials; they can be operated for a long time at temperatures up to 1000-1500°C. From quartz and oxide INORGANIC FIBERSv. produce filters for aggressive liquids and hot gases. Electrically conductive silicon carbide fibers and threads are used in electrical engineering.
Literature: Konkin A. A., Carbon into other heat-resistant fibrous materials, M., 1974; Kats S. M., High-temperature heat-insulating ma-
materials, M., 1981; Fillers for polymeric composite materials, lane. from English, M., 1981. K. E. Perepelkin.
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