CS258224B1 - Composite fiber based on isotactic potypropytane and its production method - Google Patents

Abstract

The object of the solution is a composite fiber based on isotactic polypropylene with adjustable density, with limestone particles placed in cavities elongated in the axial direction of the fiber, with pores and cracks in the fiber surface and a method of its production. The fiber is suitable as an additive to silicate building materials and paper, to filter and separation oleophilic layers, to textiles for thermal and sound insulation, to products with the feel of natural and animal fibers. The above purpose is achieved by spinning a mixture of isotactic polypropylene and limestone under defined rheological conditions given by the relationship: 3 ln (n/bs) = Σ bi · (ln/bs.D/)i_1, i=l where η is the apparent viscosity in Pa.s, b =exp(b,. .c).exp(b4+bs/T), with by=-0.37244, b3= =-0.041112, b4=-18.212, bs=6254, b6»l,2900, D is the uncorrected shear rate in s-1, T is the spinning temperature in °K and c is the mass fraction of limestone, and by drawing the fiber under defined technological conditions according to the relationship: 2 P= + a2.o + a3>c + λ .(a^.c + a5.t + ag. .c.t), where c is the mass fraction limestone in unstretched fiber, λ is the total stretch ratio, t is the stretch temperature in °C, ai=893.3, a2=638.6, a3=843.8, 84=-167.4, as=0.0230, ac=0.2974 and P is the controllable density in kg.m"' in the range from 893.9 to 1,114.4 kg.m*3. The mass fraction of limestone c is in the range from 0.001 to 0.300.

Description

258223 2

The subject of the invention is a composite fiber based on isotactic polypropylene with a controllable density for use in particular as additives for paper mixtures, silicate building products, textile materials especially for technical applications and the method of its production. Hollow, porous, porous, filled polypropylene fibers are known.

Hollow polypropylene fibers comprise one or more continuous voids in the axial direction of the fiber, as described, e.g., in Pat. JP 66 113/82. Fibers of this type are not known which have inorganic particles deposited in these cavities. Porous polypropylene fibers contain pores oriented in the radial direction of the fiber and simultaneously crystalline inorganic compound is solved by improving the dyeability of such fibers as disclosed in Pat. JP 105 912/75.

A special type is a combination of hollow and micro porous fibers according to e.g. JP 52 123/81, which is used, for example, for the separation of gases and liquids.

Known are polypropylene fibers matted and filled with inorganic substances.

However, controllable density-controlled polypropylene fibers are not known, in which the combination of limestone addition and fiber production conditions regulates its density and the process for their production is unknown.

The essence of the present invention is a composite fiber based on isotactic-polypropylene with a controlled density and a method for its production. The control of the density of the composite fiber is achieved by combining the addition of limestone, the particle size of which is below 10 microns of cavities extending in the axial direction of the fiber in the vicinity of limestone particles and pores by cracks on the fiber surface as a result of a defined method of producing the density-adjustable composite fibers of the invention. The density of composite fiber p in kg.m-3 is controllable and satisfies the relationship: p = ax + a2.c + a3.c2 + λ. (a4 <c + a5-t + ag.ct) (I), with a deviation from the experimentally determined density of max. 2%, where c is the mass fraction of limestone and the undrawn fiber, λ is the total draw ratio, t is the drawing temperature in ° C , a1 = 893.3, &amp; 2 = 638.6, aj = 843.8, a4 = -167.4, and ^ = 0.0230, ag = 0.2974 and p reaches values in the range from 893, 9 kg.m ”3 to 1,114.4 kg.m 3. The mass fraction of limestone in the unbound fiber is from 0.001 to 0.300. The principle of the process for the production of isotactic polypropylene-based composite fiber with adjustable density is that the mixture of isotactic polypropylene and limestone in the appropriate weight ratio is spun into non-elongated fiber at defined rheological ratios, satisfying relationship: 3 ln (η / b8) = Σ bi · with the deviation from the experimentally determined values of max. 13%, where η is the apparent viscosity of Pa.s, bs = exp (bg.c). exp (b4 + b5 / T), with bj * 10,604, b2 = -0,37244, b3 = -0,041112, b4 = -18,212, bj = 6,254, bg ”1,2900, D is uncorrected Shear rate at the spinner s 1, T is the spinning temperature in ° K and the non-stretched fiber owes at the temperature and the total length ratio according to the desired fiber density according to the equation I equation.

The present invention provides a novel type of isotactic polypropylene based fiber with a controllable density and a method for its production. This type of fiber allows the application of polypropylene-based fiber applications, especially in the areas of technical applications.

The isotactic polypropylene based composite fiber of the present invention has a multiple technical effect. It can be used in application areas where it is required

Claims (2)

258223 increased or certain density of polypropylene-based fibers, e.g. It can be applied in areas where an increased fiber surface is required, - pores and cracks in the fiber surface, eg in silicate matrix composites, filtering and separating materials for oily substances. The surface characteristics and cavities in the fiber mass allow diffusion of gases and liquids into the subsurface cavities of the fiber associated with the pores and cracks as well as the interaction of the diffusing substances with the limestone particles deposited in these cavities. The controllable density-controlled composite polypropylene fiber formed by the isotactic polypropylene matrix in which limestone particles having a size not exceeding 10 microns are dispersed at a weight fraction of limestone of from 0.001 to 0.300. The limestone particles are deposited in the cavities of the loosened fibrillar structure of the fiber which are elongated in the axial direction of the fiber. There are pores and cracks on the fiber surface. The extent of elongation of the cavities in the axial direction of the fiber, as well as the size and abundance of pore cracks in the fiber surface, can be controlled by the process of the present invention, the conditions of the drawing process. The increasing draw ratio causes an increase in elongation in the axial direction of the fiber, an increased number of pores and cracks in the fiber surface. The number of cavities in the fiber and the pores and cracks in the fiber can be influenced by the concentration of the dope in the fiber mass. The decreasing drawing temperature aids in the formation of voids in the fiber mass and pores and cracks in its surface. By combining the aforementioned basic fiber preparation parameters, in keeping with the defined rheological ratios in the process of preparing the non-stretched fiber, it is possible to control the density of the composite polypropylene fiber, its internal structure, and its surface characteristics. The composite polypropylene fiber of the present invention can be used as an additive of silicate builders, paper, sound and heat insulating layers, filtering and separating oilophilic layers, textile articles with a touch of natural or animal fibers. Relationships I and II. were determined by the nonlinear regression method by computer processing of 80 experimental results for the relationship between I and 149 experimental results for relationship II. EXAMPLE 1 The initial requirement was a modified polypropylene fiber with increased surface density at the level of conventional polypropylene fibers for application to fiber reservoirs of writing fluids. The fiber was prepared from a mixture of isotactic polypropylene and micronised limestone with an average particle size of 2.8 microns, a density of 2,620 kg.m 3 and a particle size fraction below 10 microns 0.96, which was spun at 230 ° C and uncorrected shear rate 172 s-3. The mass fraction of limestone was 0.01. The apparent viscosity of the mixture was 158 Pa.s and the apparent viscosity of II. was 156 Pa.s. The selected composite fiber density was 896.5 kg.m-3, which, according to I., corresponds to a 1: 3.25 draw ratio at 25 ° C. Under the stated process conditions, a fiber of unit length weight of 4.4 dtex, a relative tear strength of 3.7 cN.dtex 3, a ductility of 46%, which little limestone particles deposited in the cavities extending in the axial direction of the fiber, were obtained with pores and -3 cracks in the fiber surface and whose experimentally determined density was 896.9 kg. By utilizing this fiber in the writing fluids reservoirs, the affinity of the writing fluids to the fiber surface was increased by 101% compared to the unmodified polypropylene fiber prepared under the same technological conditions. .