CS276302B6

CS276302B6 - Polypropylene fiber with increased thermoplastics and a method of producing it

Info

Publication number: CS276302B6
Application number: CS439689A
Authority: CS
Inventors: Lubomir Ing Csc Knotek; Peter Ing Csc Michlik; Zoltan Beck; Dusan Ing Vrba; Maria Ing Bernatova; Marta Takacova; Michal Sedlak
Original assignee: Vyzk Ustav Chem Vlaken
Priority date: 1989-07-19
Filing date: 1989-07-19
Publication date: 1992-05-13
Also published as: CS8904396A2

Abstract

Polypropylénové vlákno so zvýšenou termoplastičnosťou griemeru 16 až 30 jum je vytvořené z aspoň 94 % izotaktického polypropylénu. Technický účinok sa dosahuje tým, že jádro a plášť majú rozdielnu nadmolekulovú štruktúru. Hodnoty priemerného optického dvojlomu vlákna a jeho plášťa sa líšia aspoň o 10 % entalpia topenia vlákna je menej ako 71 J.g~ . Vlákno je vhodné na výrobu termoplasticky spevnovaných netkaných vláknitých útvarov. Spósob výroby hoře uvedeného vlákna tak, že při zvláknovaní pósobi na taveninu inerciálna sila, ktorej velkosť 3.10-' až 5.10~'N je daná súčinom hmotnostného prietoku taveniny a rozdielu rýchlosti taveniny vo výtokovom otvore a po dosiahnutí priemeru 20 až 40 >um, pričom táto sila pósobi do vzdialenosti 50 mm od výtokového otvoru.Vzniknuté ochladené vlákno sa následné dlži na dlžiaci poměr menší ako 1:2,25.Polypropylene fiber with increased thermoplasticity of griemer 16 to 30 jum is made of at least 94% isotactic polypropylene. The technical effect is achieved by the fact that the core and the shell have a different supramolecular structure. The values of the average optical birefringence of the fiber and its sheath differ by at least 10%. The melting enthalpy of the fiber is less than 71 J.g~. The fiber is suitable for the production of thermoplastically reinforced non-woven fibrous structures. The method of producing the above-mentioned fiber such that, during spinning, an inertial force acts on the melt, the size of which is 3.10-' to 5.10~'N is given by the product of the mass flow of the melt and the difference in the speed of the melt in the outlet hole and after reaching a diameter of 20 to 40 µm, while this force acts at a distance of 50 mm from the outlet hole. The resulting cooled fiber is then debt to debt ratio less than 1:2.25.

Description

1 CS 276 302 361 EN 276 302 36

Vynález sa týká polypropylénového vlákna, rieši zvýšenie jeho termoplastičnosti, vý- znantnej vlastnosti pre jeho aplikáciu na teplom spevnované netkané textilie.The present invention relates to a polypropylene fiber, addressing the enhancement of its thermoplastic properties, a significant property for its application to heat-reinforced nonwovens.

Polypropylénové vlákna sú tvořené polymorfným systémom, tj. obsahujú ako kryštalický,tak i amorfný podřel izotaktického polypropylénu. Doteraz známe polypropylénové vlákna po-užívané na výrobu vlnařských či bavlnářských priadzí, mechanicky, či chemicky spevňovanýchnetkaných textiílií sa vyznačujú charakteristickými vlastnosťami akými sú dížková hmot-nost’, resp. hrúbka, pevnost’, ťažnosť, počet oblúčkov na jednotku dížky, povrchová úprava.Pre dosiahnutie týchto vlastností v optimálnych hodnotách sa v procese výroby využívajúpreto postupy zvlákňovania a díženia tak, aby vel’kosť a orientácia kryštalickej časti poly-morfného systému, ktoré zásadné ovplyvňujú pevnost, boli dostatečné, bez ohladu na komplementárny amorfný podiel, ktorý je potom rozmiestnený v prereze vlákna viac menej štatisticky. Pře nové progresivně postupy spevňovania netkaných textilií však tieto vlákna majú ne-výhody. Při spevňovaní netkaných textilií teplom pře vytvorenie adhézneho spoja - vaznéhobodu je potřebná přítomnost' dostatočného množstva adhéziva - amorfného podielu na povrchuvláken. To znamená, ,že kým při spracovateískej teplote pojenia kryštalický podiel vláknazabezpečuje pevnost vlákna, vfibec neovplyvňuje pevnost adhézneho spoja, ktorá je danáamorfným podielom. Naviac, využitelným adhézivom je len část, ktorá je přítomná v povrcho-vej vrstvě vlákna. Známe je riešenie problému zvýšenia termoplastičnostl bikomponentnýmzvláknovaním. Problém adhéziva na povrchu sa rieši tým, že jádro je tvořené poiyméroms vyššou teplotou topenia ako má polymér tvoriaci plášť, alebo sú usporiadané spňsobom"bok po boku". Toto riešenie je známe pod ochranným označením ES Fiber firmy CHISSO Corp.,jap. patent 128666. Známe je tiež dosiahnutie pokroku v riešení problému využitím procesuzvlákňovania zmesí dvoch polymérov s rozdielnou teplotou topenia, ako to uvádza japonskýpatent 147659 pře zmes polyesteru a polyolefínu, alebo jap. patent 686917 pře zmes poly-propylénu a polyetylénu. Nevýhodou všetkých týchto riešení je, že zásadné vyžadujú dvapolyméry, špeciálne strojnotechnologické zariadenia. Dosahovanie nízkých dížkových hmot-ností vláken si vyžaduje úpravu Teologických vlastností taveniny.Polypropylene fibers are made up of a polymorphic system, i.e. they contain both crystalline and amorphous coatings of isotactic polypropylene. The so-called polypropylene fibers used for the manufacture of woolen or cotton yarns, mechanically or chemically reinforced fiber fabrics are characterized by their characteristic properties such as length weight and weight. thickness, strength, ductility, number of curves per unit length, surface treatment. In order to achieve these properties at optimal values, the spinning and spinning processes are used in the manufacturing process so that the magnitude and orientation of the crystalline part of the polymorphic system that substantially affect strength, sufficient, regardless of the complementary amorphous fraction, which is then distributed more or less statistically in the fiber cross-section. However, the novel progressive processes for strengthening nonwovens have these advantages. When the nonwovens are reinforced by heat to form an adhesive bond, the presence of a sufficient amount of adhesive-amorphous portion on the surface of the fibers is required. That is, while the crystalline portion of the fiber provides fiber strength while processing the bonding temperature, it does not affect the strength of the adhesive bond which is the damamorphic portion. In addition, the usable adhesive is only the portion that is present in the fiber surface layer. It is known to solve the problem of increasing the thermoplasticity by bicomponent coating. The problem of adhesive on the surface is solved by the core being formed by a polymer having a higher melting point than the polymer forming the sheath, or arranged in a "side-by-side" manner. This solution is known under the trademark ES Fiber of CHISSO Corp., jap. It is also known to make progress in solving the problem by utilizing the process of fibrillating mixtures of two polymers with different melting points, as disclosed in Japanese Patent 147659 to a mixture of polyester and polyolefin, or jap. No. 686917 to a mixture of poly (propylene) and polyethylene. The disadvantage of all these solutions is that they require two polymers, especially machine technology equipment. Achieving low fiber lengths requires adjustment of the rheological properties of the melt.

Podstatou tohto vynálezu je vlákno tvořené jedným druhom polyméru, a to aspoň 94 %izotaktického polypropylénu, pričom nadmolekulová štruktúra jadra a plášťa tohto vláknaje rozdielna. Rozdiel je možné vyjádřit pomerom hodnot optického dvojlomu plášťa k prie-mernej hodnotě, pričom celkové množstvo adhéziva (ktoré je komplementárně ku kryštalickejčasti) je zaručené tak, že entalpia topenia vlákna nie je vačšia ako 71 j.g-'1', čo předsta-vuje stupeň zakryštalizovania menší ako 53 %. Podstatou spfisobu výroby takéhoto vlákna jeriešenie technologických podmienok prieťahu vlákna pod hubicou tak, že v závislosti odhmotného prietoku taveniny inerciálna sila posobiaca na taveninu počas jej prieťahu navlákno je nižšia ako 5,5.10"7N. Přitom táto sila pfisobí na dráhe vlákna maximálně dovzdialenosti 50 mm, pričom priemer vlákna dosiahnutý v tejto vzdialenosti od hubice jeod 20 do 40 /im. Aby výsledná nadmolekulová štruktúra vlákna bola radiálně diferencovaná,i po dížení, dížiaci poměr následného kontinuálneho díženia nemá byť váčší ako 1:2,25,nakolko pri vyšších dížiacich pomeroch sú vytvořené podmienky pre rast kryštalitov v sme-re kolmom na os vlákna, čo potvrdzuje změna dichroizmu vláken dížených na vyšší dížiacipoměr. Výhody dosiahnuté riešením sú v prvom radě v tom, že inerciálna sila, teda silapotřebná na zrýchlenie taveniny počas prieťahu je oproti doterajším technológiám řádové nižšia. Při sposobe podl’a vynálezu pri odťahovacej rýchlosti 0,91 m.s”·1 a hmotnostnom -7 -1 -7 prietoku 5,5.10 kg s je inerciálna sila celková 4,8.10 N. Pri doterajšich technolo-giách pri odťahovacej rýchlosti 9,6 m.s"'1' a hmotnostnom prietoku 1,67.10"^ kg.s-1 celko-vá inerciálna sila potřebná na zrýchlenie taveniny na konečný priemer vlákna l,6.10”^N.Výhodou sú i nižšie odťahovácie rýchlosti. Ďalšou výhodou je, že množstvo tepla, ktoré jepotřebné odniesť z jedného polymérneho prúdu taveniny počas tvorby vlákna je oproti dote-rajším technológiám zhruba 50 krát nižšie. Výhodou je i relativné krátká dráha pre dosia-hnutie konečnej hrůbky vlákna. Tieto faktory spolu s radiálnym gradientom teploty vo vlák-ně sposobujú rozdielnosť nadmolekulovej štruktúry jadra a plášťa vlákna. Konečnou výhodouvýrobku je potom zvýšená termoplastičnosť, ktorá sa prejavuje pri tepelnom spevňovaníSUMMARY OF THE INVENTION The subject of the present invention is a fiber of one kind of polymer, at least 94% isotactic polypropylene, wherein the super-molecular structure of the core and the sheath of the fiber is different. The difference can be expressed by the ratio of the optical birefringence of the jacket to the average value, whereby the total amount of adhesive (which is complementary to the crystalline part) is guaranteed so that the filament enthalpy is not greater than 71 µg, which is a degree of crystallization less than 53%. The essence of the method of producing such a fiber is to solve the technological conditions of the filament under the spout so that, depending on the tangential melt flow, the inertial force melt during its ducting is less than 5.5.10 "7N. wherein the diameter of the filament reached at this distance from the nozzle is from 20 to 40 µm. In order for the resulting super-molecular structure of the filament to be radially differentiated, even after cutting, the splitting ratio of the subsequent continuous filament should not be greater than 1: 2.25, since the conditions for the growth of crystallites in the vertical perpendicular to the fiber axis, which is confirmed by the change in the dichroism of the fibers cut to a higher diameter, the advantages achieved by the solution are in the first row that the inertial force, i.e. the force required to accelerate the melt during drafting, is higher than prior art. According to the invention, at a withdrawal rate of 0.91 ms -1 and a mass -7-1 -7 flow rate of 5.5.10 kg s, the inertial force is a total of 4.8.10 N. With the prior art at the withdrawal rate 9.6 ms " 1 " and a mass flow rate of 1.67 * 10 < 4 > kg.s-1 total inertial force required to accelerate the melt to a filament end diameter of 1.6.10 < - > N. Another advantage is that the amount of heat that is required to be removed from one polymer melt stream during fiber formation is about 50 times lower compared to conventional technologies. The advantage is also a relatively short path for reaching the final ridge of the fiber. These factors, together with the radial temperature gradient in the fiber, cause a difference in the super-molecular structure of the core and the fiber sheath. The final advantage of the product is then the increased thermoplasticity that is manifested in the thermal consolidation

Claims

CS 276 302 B6 2 fiber formations. The increased thermoplasticity of the fiber according to the invention allows high speeds of the calenders strengthening the fibrous structure in achieving sufficient strengths of these formations. Example 1 A melt containing 94.7% isotactic polypropylene was spun at 190 ° C. The melt flow rate through a 50,400 hole nozzle with a 0.4 mm hole diameter was 2.10 "5 kg.s-" ·. The stream of air-cooled fibers had a speed of -1-7 0.9 msec at a distance of 45 m and a diameter of 32 µm, causing an inertial total force of 3.5.10 N. The cooled fiber was driven to a drawing ratio of 1: 2.15 to obtain a fiber thickness 20.7 Aim, optical 29.5.times.10@5, optical double coat of 35.6 .mu.l. The OSO method determined the fusion enthalpy of 69.8 [mu] g-1. The fibers were processed into a non-woven fibrous structure which had a tensile strength of 34 N at a basis weight of 20 g (ČSN 80 0812). Example 2 A melt containing 95.4% isotactic polypropylene was spun at 200 ° C. The melt mass flow through one nozzle aperture of 0.4 mm was 5.5.10? Kg.s? The flow of air-cooled fibers had a velocity of 0.9 m at a distance of 45 mm and an average of 39 µm, with an inertial force of 4.83.10 -7N. The cooled fiber was cut successively at a ratio of 1: 2.0, giving a fiber thickness of 26.5 µm, an optical twin diameter of 30.8.10 ° C optical double bead 35.3.10. Fibers were processed into a nonwoven fibrous formation, with a tensile strength of 38 N at a weight of 24 gm. Example 3 For comparison to Examples 1 and 2, a melt containing 95.1% isotactic polypropylene was spun at a temperature of 280 [deg.] C. The melt flow rate through the 1.0 mm diameter nozzle orifice was 7.3.10 < 3 > kg.s < 2 >, and the melt velocity in the outlet port was 0.01305 ms -1. 10 ms - '*' velocity, which also yielded an inertial force of 7.29.10- ^. Cooled fibers sapo stand! owed a split ratio of 1: 3.5. 20 µm thick fibers were obtained which, in comparison with Examples 1 and 2, had a significantly higher strength of up to 4.1 cN / dtex. However, the higher fiber strength did not appear in the higher strength of the calendered nonwoven fabrics, while the tensile strength of 29 N at a basis weight of 23 g.m was achieved. The lower thermoplastics of these fibers are due both to the lower content of the non-crystalline phase, Co, expresses the enthalpyatopenia of the fiber 81 O-gl and to the super-molecular structure of the fiber, which represents the average optical birefringence of the fiber 31.2.10 ”and the jacket 32.1.10”. Compared to these fibers, the fibers mentioned in Examples 1 and 2 have increased thermoplasticity. PATENT CLAIMS

A polypropylene fiber having an increased thermoplastic diameter of 16 to 30 winters formed by at least 94% isotactic polypropylene, characterized in that it has a different superstructure molecular structure of the core and shell, wherein the difference between the optical birefringence value and the average optical birefringence of the fiber is at least 10% and in that the enthalpy of the heating of the crystalline phase of the fiber is less than 71g / g.

2. A method for producing a polypropylene fiber according to claim 1, characterized in that the material of the isotactic polypropylene is spun through a nozzle outlet opening of 0.4 to 0.6 mm diameter at a mass flow rate mv in kg.sup. wherein at a distance of -1 at a maximum of 50 mm from the spinneret, the resultant fiber reaches the velocity in ms i

With a weight of 20 to 40 µm, the mass flow rate and the withdrawal rate are in the range of 3.10-7 N µCi / µl / vfl), and in that the fiber thus prepared is proportional to the cutting ratio less than 1: 2.25.