DE1769329A1 - Endless composite thread - Google Patents

Description

DR. ING. A.VAN DERWERTH * 21 HAMBURG-HARBURG

W! LSTORFER STR. 32 - TEL. (0 * II) 77 08 61

DR. FRANZ LEDERER

β MONKS 80

LUCILE-GRAHN-STR- 22 -TEL. (08 111 44 08 46

Munich, May 9, 1968 P / U /

Applicant; HERCULES INCCEEORATED, 91.0 Market Street, Wilmington, Delaware, V, StoA.

¹¹ Endless composite thread ⁿ

The invention relates to synthetic fibers which have a high Show a degree of bulk or curl. In particular it concerns endless polypropylene threads of a new structure, that curl or become puffy spontaneously.

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In the last few years, synthetic fibers have increasingly occupied a broader position in the textile market. Since ₉ where wool and cotton are essentially unchallenged materials have been used by the textile industry, these are now being replaced in some areas of application by nylon,? and acrylic fiber?!, and has recently been replaced by olefin fibers, especially polypropylene fibers. Synthetic fibers have properties such as "B _s ease of maintenance, resistance, mechanical strength and heat, combined with low weight, to name only a few of which are not found in the older, natural textile materials.

However, on the other hand, woolen fabrics have advantages which up to now only with extreme difficulties and Costs, if at all, could be reproduced for the man-made fiber fabrics ) woolen yarns or fibers have a high degree of natural crimp. As a result, they have a high degree of bulkiness and Bowohl has excellent protective properties . as well as having good elastic properties, such as dispersibility, compressicine recovery energy and liveliness. In addition, wool has a very pleasant surface grip that consumers are inclined to use

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are to be preferred «

Many attempts have been made to produce synthetic fibers or yarns which, after being converted into a Fabric should result in a product that has the desired

evaluate properties of wool in addition to the desirable ones Properties of synthetic fibers. Many of these attempts contributed the features of procedures to which the synthetic yarns have been given a crimp. Me most successful attempts were those at which have a spiral or helical crimp was awarded.

To achieve a helical crimp, it has been proposed to use the synthetic polymer in the form of a Composite endless padens, consisting of two or more different, although generally related polymers are spun in side-by-side or in shell and core bonds are united «When the sinless fadeh in common in the processing of synthetic fibers " Way ^ and then relaxed, the different polymer segments show different Relaxation or shrinkage potentials. This differential scraping results in a helical turn of the individual Bndless pad. When such sinless threads become a yarn

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are combined, the resulting yarn turns out to be highly puffy, which is due to the difficulties • on which the helically wound endless = threads when they want to stay in close proximity to one another.

In British patent specification 979 003, the proposal is made to produce a self-bulging endless thread from polypropylene by making a composite endless " Thread containing two different polypropylene components, which in their Intrineic-Viekositäten around a certain Different amount, crazy. This differential shrinkage of the two polypropylene components caused the aforementioned helical winding up when the yarn is relaxed after stretching.

It has now been found that composite continuous filaments which show a high degree of spontaneous crimp are made of polypropylene and a crystalline copolymer of propylene and up to about 25 ° of ethylene or of a ^ 5 -olefin with up to 6 carbon atoms can be produced. These filaments, after stretching followed by relaxation, can produce a helical crimp of about 5 to 100 crimps per inch (about 2 to crimps per cm)

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The composite filaments of the present invention are in contrast to the prior art as exemplified is cited by UK Patent Specification 979,003, referred to above, with regard to the formation of the crimp independent of differences in intrinsic viscosity, the molecular weight or the molecular weight distribution, this is advantageous because it is not always easy to polymerize to manufacture according to MaS with exactly the desired differences in such properties. Ss is however relatively easy to create copolymers which are different from homopolymers.

Another advantage of the composite cordless threads of this invention over those of the prior art in which each component of the cordless thread is a homopolymer is the mechanism by which the crimping was by differential shrinkage. Bs was found to be in the case of bonded Homopolymers, the continuous filaments had to be stretched to achieve an optimal crimp level under such conditions that a relatively high concentration of so-called * micro-pores. * Are formed in one and only one component of the composite. These * micro-pores ¹¹ are actual pore spaces in the polymeric acid structure, which are believed to be caused by pulling aside poly-

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merisat crystals formed during the stretching process will. Such pores are not visible to the naked eye, but collectively they give the endless thread a chalk-white appearance. When the yarn is heated to effect the shrinkage, the shrinkage occurs through (1) disorientation of the polymer molecules and (2) Closure of these pores takes place. It has been found that the greater effect is achieved in the case of linked homopolymers the pore closure occurs, which results in greater shrinkage due to the pore component. However, the process conditions are quite critical and require that Maintaining specific temperature levels at each stage of the process from spinning to relaxation ensure that a high level of forum formation occurs in only one component and that the main structural effect is caused by the closure of the pores.

The pore formation of one of the components, however, does not participate in the formation of the helical crimp due to the differential chucking of the components Bndloe Pads of the Present Invention. Rather, the stretching process is carried out under conditions which essentially no forum formation at any Component takes place. Thus, the potential problems and dangers of pore phenomena are avoided

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Polymers and copolymers of propylene useful in this invention are those which have a substantial degree of crystallinity. Since the crystallinity cannot be measured very easily, it is more expedient to define it by means of the density of the polymer. It is known that a completely amorphous copolymer of ethylene and propylene or a completely amorphous (atactic) homopolymer of propylene has a density of 0.85. A completely crystalline homopolymer of propylene has a density of about 0.935β. The well-known "crystalline ¹ * polypropylene and the" crystalline "block and random ethylene-propylene copolymer leate commercially available have densities of usually about 0.88 to about 0.91. The expression "crystalline polymers and copolymers" used below in this description can be taken as an indication that such a material has a density of at least about 0.88.

The polypropylene homopolymeric acid used as one of the components of the composite fibers of this invention can be any isotactic polypropylene having an intrinsic viscosity in the range of about 1.5 to 4 and a density of at least 0.88. Such poly _t merisate are well known and readily available _e

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Particularly useful copolymers are those made from polypropylene and a second olefin which are crystalline are, and a maximum of about $ 25> of the second olefin. These can be block or random copolymers Be type. In the following description, the method of copolymerization with ethylene is used as another Monomers described. However, the processes are equally applicable for the production of Oopolymerieaten of Propylene with other GC oils with up to 6 carbon atoms.

Block copolymers are those, which mainly consist of isotactic polypropylene chains, but one or more blocks of either ethylene homopolymer or ethylene-propylene Copölymerisat in the molecule "These copolymers normally contain about 3 to 25 i» ethylene. Products of this type are produced by the sequential polymerization of (1) propylene and (2) either a mixture of propylene and ethylene * or ethylene alone, or vice versa. The most convenient method for producing such preparations is that propylene is homopolymerized in the presence of a stereospecific catalyst in a liquid diluent to form a homopolymer and then ethylene is introduced ₉ during

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some unpolymerized propylene remains in the reaction vessel _o At this point, the polymerization continues as a copolymerization. Viewed theoretically, the product of such a process should be composed of macromolecules in which one or more segments of the homopolymer of propylene (PP) alternate with one or more segments of a random copolymer of propylene with ethylene (B?) To form a product with the theoretical structure t

(1) (PP-EP) _n or

(2) (PP-EP) _n PP

where η represents an integer of 1 or more depending on the number of polymerization sequences. If the polymerization of the ethylene monomer was continued after the propylene had been consumed, the theoretically repeating unit has the structure (PP-BP-BB) _n , where BE is a homopolymer of ethylene. However, there is evidence that the so-called "block copolymer" is actually an intimate mixture of a 'homopolymeric acid of propylene and a copolymer of the two monomers and, advantageously, of a homopolymeric acid of ethylene, the mixture being homogeneous in the sense that it is uniform Dispersion of the polymer components is present through the whole mixture. Therefore, when the term ee "block copolymer" is used, ee is not ¹

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on

intended »the meaning -de * polymeric compositions of real block copolymer structure, rather it is intended to be the compositions commonly referred to as "block copolymers" should be included, even if this is not precisely the case. Such copolymers preferably have an intrinsic viscosity of about 2 to 4 »block copolymers of these and other types and their Education are inter alia in US Pat. No. 3,301,921, Australian Pat. No. 253,751, the British patents 889 230 and 915 662 and French patent 1,290,523.

Random copolymers are those in which the ethylene is distributed over the entire molecule, but not according to a predetermined plan, but statistically depending on the relative concentrations of the two monomers in the reaction mixture. This type of polymer is made by continuously feeding both ethylene and propylene at a predetermined ratio. The polymer obtained 1st crystalline as defined above (ie density of at least 0.88) Xthylengehalt case of low ale jfi about 10, preferably about 2 to 5 $>.

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the

The properties Xn of the various components of the Composite continuous filaments applied polymers are by no means critical for use in this invention insofar as they are not critical for typical synthetic applications Endless threads bind. Therefore, the density ranges given above are those normally used for any one Application for an endless thread can be expected. The same is for the intrinsic viscosity range of approx. 1.5 to 4 apply.

As in the case of propylene with more conventional ones Applications of synthetic filament are heat stabilizers, light stabilizers and antioxidants also included in the approaches. Any, usually applied stabilizer-antioxidant systems will. Such systems are well known to the person skilled in the art and there is therefore no need for a discussion thereof Job. Other additives such as dyeing auxiliaries, pigments and fillers can also be included.

The ratio of the components in the composite continuous filaments This invention can vary from about 1 to 4 to 4 to 1. Usually, however, the filaments are about equal proportions included by each component.

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176S329

The various components of the endless B filaments can be arranged in either a side-by-side or a sheath-and-core configuration. Usually the side-by-side arrangement is satisfactory and is preferred. The sheath-and-core assembly is usually applied in those cases in which a significant difference in properties between the polymers in the two components, Z ₀ B. where a less stable or less stable or chemically inert less than the other is. The shell-and-core arrangement gives the internal component protection through the external components. In the present package, there are only very small differences in the properties between the components, with the exception of the shrinkage potential. Thus, there is usually no need for sheath-and-core protection. However, the sheath-and-core arrangement can be used when other considerations make it desirable.

Generally speaking, the production of endless threads carried out according to standard methods, with the exception of the Simultaneous spinning of a large number of polymer streams. This is intended to indicate that the polymer is in the form under pressure a melt extruded through a die and a substantially non-orienting melt stretching

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is subjected to the bottom, increasing the thickness of the Bndlos thread experiences a reduction. The formed continuous thread is then subjected to an orienting cold drawing. The. Crimp is then created in the drawn yarn by heating it in a substantial manner developed tension-free state.

Suitable spinning equipment for making filaments having any of these configurations is known to those skilled in the art and does not form part of this invention. Regarding disclosures about equipment for education refer to US Patents 3,192,562, 3,181,201, 3,176,346, 3,176,345, 3,176,343, 5 176 342, 3 161 914 and many others.

The basic design feature of these spinnerets is the provision for dividing the polymer into more than one stream, the streams converging and touching each other at a point at or immediately in front of the extrusion nozzle. The specific spinneret design determines whether the resulting filament is of the side-by-side or sheath-and-core configuration. The contact between the streams always takes place as long as the polymer is molten, so that the various components can fuse into a single, well-adhering, composite structure after cooling. " That spinning can take place at a temperature between 190 and 325 ⁰ C,

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preferably between about 250 and 300 ⁰ C are carried out.

In most cases, the spinning is effected by a spinneret which has a large number of conjugated nozzles. The resulting plurality of composite filaments are usually combined into a yarn, which is then subjected as a whole to the remaining treatment stages, After the yarn has passed the drawing and has passed through a relaxation stage, it has a substantially greater bulkiness due to the helical twist or curl that the individual Endless thread was awarded «

The orientational drawing is carried out at a temperature below the melting point of polypropylene, but above the temperature at which any of the components forms pores, in order to develop the optimum properties of the continuous filament. The stretching temperature is preferably between about 80 and 110 ^° C. in order to develop the optimum of elongation properties and also the necessary different shrinkage potential. Ss a stretch of at least about 150 j6 is required to achieve a. Achievement of usable crimped continuous filaments or yarn sufficient · generate shrinkage see below.

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The stretching is well known to those skilled in the art Work process carried out «I am preferred process is the stretching in the narrow gap between a "differently driven feed roller and a draw roller" The feed roller is used to heat the yarn on the correct stretching temperature, whereas the draw roll is normally kept at around room temperature. In some cases, the pull roller can be used if desired be heated.

In some cases, the drawn filaments pucker spontaneously as soon as the tension imposed by the stretching operation is released. In other cases the crimp is achieved by applying heat to the filaments developed in a relaxed state, which causes them to shrink, whereby the differential shrinkage effect is set in motion is brought. The heat treatment is preferable

Partially white, for example carried out with boiling water or in an oven, namely at a point above the point at which the copolymer component shrinks, but below the point at which there is a substantial shrinkage of the homopolymer component. takes place. Usually this will be the case at a temperature between about 90 and 15O ⁰ C. The specifically selected temperature is also dependent on the

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Ethylene content of the copolymer component, with

at em

higher temperatures Zein / ethylene content In the range of the lower limits is preferred? "The heat treatment is carried out for about 0.2 to 10 minutes. It is also possible to carry out the heat treatment continuously by running the yarn at a high speed, e.g. is moved from 100 to 1000 m / minute, brings into contact with a hot plate or is pulled through a heated zone. In such a case, in view of the high degree of yarn movement, the contact time of the yarn during the heat treatment is less than "with discontinuous" Either way, and accordingly higher temperatures are used. In the continuous process, treatment times of about 0.01 seconds to about 1 minute are used. The heat source or the zone can be kept at a temperature as high as 300 ^° C., since the contact time of the yarn with the heat source is so short that the yarn never reaches the ambient temperature. The higher temperature allows sufficient heat to be absorbed during the short contact time to cause shrinkage. When using this procedure, however, care must be taken to ensure that the yarn can shrink without noticeable development of tension. Palis as soon as tension builds up, the yarn will either break or heat-treat | (3o that there is no structural integrity at all

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is being developed.

The filaments made in accordance with the present invention can have a crimp frequency of about 5 to 100 crimps per inch. {CPI). (About 2 to 40 crimps per cm). The crimp frequency is related, among other things, to the strength of the components, the draw ratio, the draw temperature, the relaxation temperature and tension. Typically, a crimp frequency of about 5 to 40 CPI (about 2 to 15 # 7 crimps per cm) is satisfactory.

The invention is illustrated by the following examples, in which parts and percentages are parts by weight and percentages by weight unless something else is indicated.

Eg 1 1

Using a spinneret of the type shown in British Patent 979 083 having 35 nozzles 0.016 inches (approximately 0.41 mm) in diameter , a composite endless pad was made of a propylene homopolymer and a random Copolymer of ethylene and propylene, containing about 2.4 # ethylene ,, spun,.

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the components being arranged in side-by-side connection. Both components contained 0.15 wt. The homopolymer had an intrinsic viscosity of 2.2 and a density of O ₉ 90und the copolymer has an intrinsic viscosity of 2.0 and a density of 0.90. The spinning operation was carried out at 25O ⁰ C at a linear velocity
. of 665 m / minute and resulted in a spun yarn of 352 denier.

subject

The spun yarn was drawn about 3 _t 5 / using, differentially driven Binapiss and draw rollers, with an idnear total speed of about 39
or * 137 m / minute was worked. The Etnepeiswalzen temperature was 93 ° C, and that of the Zugwalae 10O ⁰ C.

Visual inspection of the yarn showed that there was no pore formation took place as a result of the stretching process

subject

would have. The 3 » 5 / drawn yarn was essentially relieved of tension by placing a strand of it on it
a Metallroet heated in an oven at 125 ⁰ C for 2 minutes. A helical crimp on the order of about 30 CPI (about 11.8 crimps per ca) was the result.

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Example 2

Example 1 was repeated using the same Eomopolymerisates In combination with an end-block copolymer containing about 25 $> ethylene repeated. The resulting yarn was heat treated in boiling water for 5 minutes and formed a hot-type crimp of about 40 CPI (about 15 »7 crimps per cm).

Example 3

Example 1 was repeated using the same Homopolymerisatee and a 3-block Copolymerlsatee containing 3 $> ethylene. After the boiling water heat treatment, a hot-like crimp of about 25 CPI (about 9.8 crimps per cm) was developed.

Example 1 was repeated using the same homopolymer and a random copolymer of propylene and about 3.2 ^ butene-t. The resulting yarn was heat treated in an oven at 125 ⁰ C for 5 minutes and formed a heiixartige crimp of about 20 CPI (about 7.9 crimps per cm) from.

Even if the invention above for cordless threads,

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containing a homopolymer component and a copolymer component, it should be recognized that this is not limited thereby. The invention also envisages continuous filaments which have more than two components, such as Z ₀ B _0, a homopolymer and two copolymer components. In most cases, however, two components create enough difference between the components to produce the desired amount of crimp. The number of com-

Complexity components the extent of 'Hoefez & ekfcößg the extrusion facility

processing, and thus the difficulty and costliness increases the production in the same way to _o In only a few cases it is necessary or wishing to be ~ worth to produce continuous filaments having more than two or at most three components.,

Bs is also within the scope of the invention, Yefbund endless threads with polypropylene in one component and a mixture of copolymers in the other £ dmponerite manufacture, ZoB. a® mixture of ethylene-propylene * and butene-propylene copolymers,

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Claims (4)

Claims 1 r. Endless composite ~ 3? Threads "'characterized by at least two components, wherein one of these components a PoIypropylen homopolymer having a density of at least Op88 and another of said components, a Copolymerißat of propylene and up to 25 i * a second .alpha.-olefin from with 2 to 6 carbon atoms and the copolymer has a density of at least about 0.88. 2. Boundless composite thread according to claim 1, characterized in that that the individual components in side-by-side connection are arranged. 3 * Endless composite thread according to claim 2, characterized in that the copolymer component is a random copolymer with a content of about 2 to 5 $> ethylene. 4. Endless composite thread according to claim 2, characterized in that the copolymer component is a block copolymer with a content of about 3 to 25 # ethylene is " 109847 / 1.7 46