CS258224B1 - Connection of drying circuit,especially for temperature chambers - Google Patents

Abstract

The eye of the solution is the composite fiber on base of isotactic polypropylene with controllable density, with limestone particles deposited in cavities extending in the axial direction of the fiber, with pores and cracks in the fiber surface and manner production. The fiber is suitable as an additive into silicate building materials and paper, to filter and separation oilophilic layers, in thermal and sound insulation fabrics, into products with a touch of natural and animal fibers. This purpose is achieved by spinning mixtures of isotactic polypropylene and limestone under defined rheological conditions given by: 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), whereby = -0.37244, b3 = = -0.041112, b4 = -18.212, bs = 6254, b6 »l, 2900, D is uncorrected Shear rate in s-1, T is the spinning temperature in ° C and c is weight a fraction of limestone, and drawing a fiber at 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 fraction by weight of limestone in the unbound fiber, λ is the total draw ratio, t is the temperature owing in ° C, ai = 893.3, a2 = 638.6, a3 = 843.8, 84 = -167.4, as = 0.0230, ac = 0.2974 and P is controllable density in kg.m "'ranging from 893.9 to 1,114.4 kg.m * 3. The mass fraction of limestone c is ranging from 0.001 to 0.300.

Description

The object of the invention is a composite fiber based on isotactic polypropylene with a controllable density, with limestone particles embedded in cavities extending in the axial direction of the fiber, with pores and cracks in the fiber surface and a method for producing the same. The fiber is suitable as an additive in silicate building materials and paper, in filtering and separating oil -ophilic layers, in textiles for thermal and acoustic insulation, in products with touch of natural and animal fibers. This is achieved by spinning a mixture of isotactic polypropylene and limestone under defined theological conditions given by:

ln (n / b _p) = Σ ^b i · (ln / _B .D /) ^I_1, i = l where η is the apparent viscosity in centipoise, b = exp (b ,.

.c) .exp (b4 + bs / T), whereby = -0.37244, b3 = = -0.041112, b4 = -18.212, bs = 6254, b6 »1, 2900, D is uncorrected Shear rate vs ^-1 , T is the spinning temperature in ° K and c is the mass fraction of the limestone, and by fiber elongation under defined technological conditions according to the relation:

= P + a ₂ + a _{3 .about>} λ + c. (A + a ^ .c _naphth-5 and _g.

.ct), where c is the mass fraction of limestone in the undrawn fiber, λ is the total draw ratio, t is the draw temperature in ° C, ai = 893,3, and ₂ = 638,6, a3 = 843,8, 84 = - 167.4, s = 0.0230, ac = 0.2974 and P is a controllable density in kg.m -1 ranging from 893.9 to 1114.4 kg.m * ³ . The mass fraction of limestone c ranges from 0.001 to 0.300.

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The subject of the invention is a composite fiber based on isotactic polypropylene with adjustable density for use as additives for papermaking mixtures, silicate construction products, textile materials for technical applications in particular and for a process for its production.

Polypropylene fibers are known to be hollow, porous, porous, filled.

The hollow polypropylene fibers comprise one or more continuous cavities in the axial direction of the fiber, as exemplified by e.g. in Pat. JP 66 113/82. There are no known fibers of this type having inorganic particles embedded in these cavities.

The porous polypropylene fibers contain pores oriented in the radial direction of the fiber and at the same time a crystalline inorganic compound is solved to improve 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. Pat.

JP 52 123/81, which is used e.g. for separating gases and liquids.

Polypropylene fibers are matted and filled with inorganic substances.

However, composite density-controlled polypropylene fibers are not known in which the density of the limestone is controlled by the combination of the addition of limestone and the technological conditions of the fiber, and the process for their production is not known.

SUMMARY OF THE INVENTION The present invention is based on a composite fiber based on isotactic density-adjustable polypropylene and a process for its manufacture. The density control of the composite fiber is achieved by combining the addition of limestone, the particle size of which is below 10 microns of cavity extending in the axial direction of the fiber around the limestone particles and pores and cracks on the fiber surface. The density of the composite fiber pv kg.m ^-3 is adjustable and satisfies the relation:

p = a _x + and ₂ .c + and ₃ .c ² + λ. (a _{4 <} c + and ₅ -t + ag.ct) (1), with a deviation from the experimentally determined density of max. 2 4, where c is the mass fraction of limestone in the undrawn fiber, λ is the total draw ratio, t is the draw temperature in ° C, = 893,3, and ₂ = 638,6, and ₃ = 843,8, and ₄ = - 167.4, a ^ = 0.0230, g = 0.2974 and p reaches values ranging from 893.9 kg.m ³ to 1 114.4 kg.m ³ The mass fraction of limestone in the undrawn fiber is from 0.001 to 0.300. The essence of the method of producing composite fiber based on isotactic polypropylene with controllable density consists in that the mixture of isotactic polypropylene and limestone in the appropriate weight ratio is spun to the undrawn fiber at defined rheological ratios satisfying the relation:

ln (η ₈ lb) = Σ p. . (ln / b _s . D /, ¹ ' ¹ (II.) i = 1 with deviation from experimentally determined values max. 13 4, where l) is the apparent viscosity in Pa.s, b _s = exp (bg.c). exp (b ₄ + bj / T), where bj * 10.604, b ₂ = -0.37244, b ₃ = -0.041112, b ₄ = -18.212, bj = 6.254, bg ”1.2900, D is uncorrected Spinning shear rate vs ¹ , T is the spinning temperature in ° K and the undrawn fiber is elongated at the temperature and to the total length by the ratio of the desired fiber density according to the equation I.

SUMMARY OF THE INVENTION The present invention provides a novel type of isotactic polypropylene fiber of composite nature with a controlled density and a method for its production. This type of fiber makes it possible to extend the application possibilities of polypropylene-based fibers especially in the field of technical applications.

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

258223 increased or certain density of polypropylene-based fibers, e.g. when applied to paper in a wet way. It can be applied in areas where an increased fiber surface is required, pores and cracks in the fiber surface, e.g. in silicate matrix composites, filtering and separating materials for oily substances. The surface characteristics and voids in the fiber mass allow the diffusion of gases and liquids into the subsurface voids of the fiber associated with the pore surface and cracks, as well as the interaction of the diffusing substances with the limestone particles deposited in the voids.

The controllable density composite polypropylene fiber of the present invention is comprised of an isotactic polypropylene matrix in which limestone particles of less than 10 microns are dispersed at a weight fraction of limestone from 0.001 to 0.300. The limestone particles are embedded in cavities of the loose fibrillar structure of the fiber, which extend 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 pores and cracks in the fiber surface, is controllable by the production method of the present invention, in particular by the drawing process conditions. The increasing draw ratio causes an increase in the elongation of the cavities 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 on its surface can be influenced by the concentration of added limestone in the fiber mass.

The decreasing drawing temperature aids the formation of voids in the fiber mass and pores and cracks in its surface. By combining the above-mentioned basic parameters of fiber preparation, while maintaining defined rheological conditions in the process of preparing the undrawn fiber, it is possible to control the density of the composite polypropylene fiber, its internal structure and surface characteristics.

The composite polypropylene fiber of the present invention can be used as an additive in silicate building materials, paper, sound and heat insulating layers, filtering and separating oilophilic layers, textile products with natural or animal fiber touch.

Relations I. and II. were determined by nonlinear regression by computer processing of 80 experimental results for relationship I and 149 experimental results for relationship II.

Example 1

The initial requirement was a modified polypropylene fiber with an increased surface area and 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 micronized limestone with an average particle size of 2.8 microns, a density of 2,620 kg.m ³ and a mass fraction of particles below 10 micrometers 0.96, which was spun at 230 ° C and uncorrected shear rate. 172 p. ^-3 . The limestone mass fraction was 0.01. The apparent viscosity of the mixture was determined to be 15 mbar and the apparent viscosity according to formula II. was 156 Pa.s. A composite fiber density of 896.5 kg.m ^-3 was selected, which, according to formula I, corresponds to a draw ratio of 1: 3.25 at a drawing temperature of 25 ° C.

Under the stated technological conditions, a fiber having a unit weight of 4.4 dtex, a relative tensile strength of 3.7 cN.dtex ³ , an elongation of 46% was obtained, which little limestone particles deposited in cavities stretched in the axial direction of the fiber with pores and -3 cracks in the fiber surface and whose experimentally determined density was 896.9 kg.m The use of this fiber in fiber writing containers of writing fluids increased the affinity of writing fluids to the fiber surface by 101% compared to unmodified polypropylene fiber prepared under the same technological conditions.

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The same undrawn fiber was drawn to a draw ratio of 1.5 at a drawing temperature of 120 ° C. A fiber having a unit weight of 9.4 dtex, relative tear strength, was obtained.

1.8 cN.dtex ^-1 , elongation 231%, which little particles of limestone deposited in cavities, elongated in the axial direction of the fiber, with pores and cracks in the fiber surface and whose experimentally

The -3 -3 density determined was 902.0 kg.m. The density according to formula I is 902 kg.m

Example 2

The initial requirement was a modified polypropylene fiber with an increased surface segmentation and a density higher than that of conventional polypropylene fibers for application to filter paper.

The fiber was prepared from a mixture of isotactic polypropylene and micronized limestone with the same characteristics as in Example 1, by spinning under the same conditions as in Example 1, except for a mass fraction of limestone which was 0.10. The apparent viscosity of the mixture was determined to be 174 Pa.s and the apparent viscosity according to formula II. was 169 Pa.s. A composite fiber density of 932 kg.m ³ was chosen, which according to formula I corresponds to a draw ratio of 1: 3.25 at a drawing temperature of 120 ° C.

Under the stated technological conditions, a fiber unit weight was obtained

5.2 dtex, a real tear strength of 3.1 cN.dtex ³ , an elongation of 32% that little limestone particles deposited in the cavities, extending in the axial direction of the fiber, with pores and cracks 3 in the fiber surface and whose experimentally determined density was 939.0 kg.m. Said composite fiber was applied without difficulty at the end of the milling process to the dutch to prepare filter paper and slightly increased the strength and air permeability of the paper. At the same time, the composite fiber has to touch natural and animal fibers.

The same undrawn fiber was drawn at a drawing temperature of 120 ° C to a draw ratio of 1: 2.0. A fiber having a unit weight of 7.3 dtex, relative tear strength, was obtained

1.9 cN.dtex ³ , an elongation of 102% by which the limestone particles deposited in the cavities, extending in the axial direction of the fiber, with pores and cracks in the fiber surface and whose experimentally

The -3 -3 density was 950.0 kg.m. The density according to the relation I. is 944.8 kg.m.

Example 3

The initial requirement was a modified polypropylene fiber with the largest possible proportion of voids in the fiber and pores and cracks in the fiber surface, at a micronised limestone concentration of 15% by weight, for use in sound and heat insulating fiber layers.

The fiber was prepared from a mixture of isotactic polypropylene and micronized limestone with the same characteristics as in Example 1, which was spun at 270 ° C and an uncorrected shear rate of 115 s ^-1 . The mass fraction of limestone was 0.15. The apparent viscosity of the mixture was determined to be 96 Pa · s and the apparent viscosity according to formula II. is 102 Pa.s.

A drawing temperature of 100 ° C and a drawing ratio of 1: 3.1 were chosen, which according to formula I corresponds to -3 density 951.2 kg.m

Under these technological conditions, a unit weight density fiber was obtained

23.2 dtex, relative tensile strength 2.0 cN.dtex ^-3 , elongation 143%, which little particles of limestone deposited in cavities extending in the axial direction of the fiber with pores and cracks in the fiber surface and whose experimentally determined density was 942.4 kgm

The same undrawn fiber was drawn at a drawing temperature of 100 ° C to a draw ratio of 1: 5.0. A fiber having a unit weight of 15.8 dtex, a relative strength of 3.1 cN.dtex ^-1 , an elongation of 24% was obtained, which had little limestone particles deposited in cavities extending in the axial direction of the fiber with pores and cracks in the fiber surface and provided

The -3 -3 density was 913.5 kg.m. The density according to the relation I. is 916.2 kg.m

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Composite polypropylene fiber composite insulating fabrics are characterized by an improved sound absorption capability over the sound frequency range of 100 to 4,000 Hz, compared to insulating fabrics of the same design and preparation technology of conventional polypropylene fibers.

Example 4

In this example, the possibilities of increasing the density of polypropylene fibers by adding micronized limestone in a weight fraction of 0.30 are shown.

The mixture of isotactic polypropylene of limestone, with the same characteristics as in Example 1, was spun under the same conditions as in Example 1, except for the weight fraction of limestone, which was 0.30. The apparent viscosity of the mixture was determined to be 193 Pa.s and the apparent viscosity was IX. is 200 Pa.s. The density controllability is documented in the following table:

T C the draw ratio Density, kg.m Exp. provided by relationship I. 25 2.0 1 068,6 1,066.0 25 2.5 1,049.0 1 042.3 25 3.25 996.0 1 006.7 120 2.0 1 084.7 1 087,3 120 2.5 1,060.0 1 068,9 120 3.25 1 048,5 1 041.4

Fibers were obtained having limestone particles embedded in cavities extending in the axial direction of the fiber, with pores and cracks in the fiber surface suitable for trapping oily substances.

Claims (2)

OBJECT OF THE INVENTION An isotactic polypropylene-based composite fiber characterized in that it consists of an isotactic polypropylene matrix in a fraction of from 0.700 to 0.999, a limestone particle in a fraction of from 0.001 to 0.300, a size of up to 10 microns, embedded in cavities extending in the axial direction of the fiber; pores and cracks in the fiber surface, the density P of the fiber in kg.m being adjustable according to the relation: P = a ₃ + and ₂ -c + and ₃ .c ² + 2. (a ₄ .c + and ₅ .t + and _g .ct) (I.) in which o is the mass fraction of limestone in the undrawn fiber, λ is the total draw ratio, t is the draw temperature in ° C, = 893,3, a ₂ = 638.6, and ₃ = 843.8, and ₄ = -167.4, and ₅ = 0.0230, βθ = 0.2974 and p reaches values ranging from 893.9 kg.m ² to 1 114 4 kg.m ³ , 2. Method according to claim 1, characterized in that the mixture of isotactic polypropylene and limestone is spun at an apparent viscosity η in Pa.s according to the formula: ln (η / b _g ) = bi bi. (ln / bg.D /) ^{1 1} (II.) i = 1 in which b _g = exp (b _g .c). exp (b ₄ + b _g / T), where b ^ = 10.604, b ₂ = -0.37244, b ₃ = 0.041112, b, = 18.212, b _c = 6.254, b, = 1.2900, D is the uncorrected spinning shear rate vs ^-1 , T is the spinning temperature in ° K and the undrawn fiber obtained is drawn at temperature t to the total draw ratio λ depending on the desired density of the composite fiber according to Equation I.