Thermoplastic fibers exhibiting durable high color strength characteristics

Abstract

Improvements in permitting brighter colorations within polypropylene fibers and / or yarns while simultaneously providing more efficient production methods of manufacturing of such colored fibers as well are provided. Generally, such fibers and / or yarns have been colored with pigments, which exhibit dulled results, or dyes, which exhibit high degrees of extraction and low levels of lightfastness. Such dull appearances, high extraction levels, and less than stellar lightfastness properties negatively impact the provision of such desirable colored polypropylene fibers and / or yarns which, in turn, prevents the widespread utilization of such fibers and yarns in various end-use applications. Thus, it has surprisingly been determined that brighter colorations, excellent extraction, and more-than-acceptable lightfastness characteristics can be provided, preferably, through manufacture with certain polymeric colorants that include poly(oxyalkylene) groups thereon. Fabric articles comprising such novel fibers and / or yarns are also encompassed within this invention.

Description

FIELD OF THE INVENTION This invention relates to improvements in permitting brighter colorations within thermoplastic fibers and / or yarns while simultaneously providing more efficient production methods of manufacturing of such colored fibers as well. Generally, such fibers and / or yarns have been colored with pigments, which exhibit dulled results, or dyes, which exhibit high degrees of extraction and low levels of lightfastness. Such dull appearances, high extraction levels, and less than stellar lightfastness properties negatively impact the provision of such desirable colored thermoplastic (such as, without limitation, polypropylene) fibers and / or yarns which, in turn, prevents the widespread utilization of such fibers and yarns in various end-use applications. Thus, it has surprisingly been determined that brighter colorations, excellent extraction, and more-than-acceptable lightfastness characteristics can be provided through manufacture with certain polymeric colorants that i...

AI Technical Summary

Benefits of technology

It is thus an object of the invention to provide thermoplastic (such as polypropylene, as one non-limiting example) fibers and / or yarns that exhibit extremely bright and aesthetically pleasing colorations as compared to pigmented products. A further object of the invention is to provide such colorations that are of very low, if nonexistent, extraction. A further object of the invention is to provide a specific method for the production of brightly colored thermoplastic fibers that permits quick and efficient changeover from one colorant to another. Additionally, another object of this invention is to provide a brightly colored thermoplastic fiber and / or yarn that exhibits outstanding lightfastness properties, either alone or in the presence of minimal amounts of UV absorber additives. Another object of the invention is to provide a process for manufacturing fibers using liquid colors in which the shade can be adjusted to match some standard.

Such colorants provide the aforementioned, highly desirable, low extraction properties, as well as the significant bright colorations as compared with pigmented fibers.

This rod-like configuration also provides effective and even colorations throughout such target fibers because of the ability of light to pass through such fibers and transparent film-like structures simultaneously. Thus, light is transmitted through such fibers as well as absorbed by the colorants therein due to the transparent appearance of the resultant fiber. The resultant appearance is, unexpectedly, very bright in nature, much more so, for example, than the empirical appearance of the above-discussed pigmented fibers that require a large amount of solid particles therein to provide even colorations throughout, but which, as a result, also exhibit very dull appearances as well. The colored transparent nature available with these inventive liquid colorants produces the bright colorations, much like a colored filter placed over a light imparts a bright, colored effect when the light shines therethrough. The fibers themselves are generally solid in nature, and, cross-sectionally, appear as round, triangular, square, and / or rectangular in shape, but may have any cross sectional shape, such as octalobal which is popular in carpet fibers.

Furthermore, such fibers may include other coloring agents, such as pigments, titanium dioxide, and the like, as well as fixing agents for lightfastness purposes. To that end, certain ultraviolet absorbers provide excellent protection from ultraviolet radiation and thus aids in reducing, if not preventing, color degradation due to such exposure. Any type of ultraviolet absorber compound or formulation that is dispersible within thermoplastics may be utilized within this invention. However, some non-limiting examples of such components include phenolic antioxidants, such as HOSTANOX® 245, O10, O14, O16, O3, and blends with HOSTANOX® M, all available from Clariant; processing stabilizers, such as HOSTANOX® PAR 24, SANDOSTAB® PEPQ (from Clariant), and blends with SANDOSTAB® QB; sulfur-containing co-stabilizers, such as HOSTANOX® SE 4 or SE 10; metal deactivators, such as HOSTANOX® OSP 1; light stabilizers, such as NYLOSTAB® S-EED (from Clariant, as well); and straightforward ultraviolet absorbers, such as CHIMAS SORB® 2020, 944, 119, and / or 119FL, TINUVIN® 783, 353, 234, 1577, and / or 622 (all available from Ciba Specialty Chemicals). Preferred is TINUVIN® 783 for such a purpose.

Problems solved by technology

However, accent yarns or other fibers that require individual colorations requires coloring during production.

In addition, some polymers such as polypropylene, polyethylene, etc., have not been heretofore able to accept dyes of any kind, and have thus been colored with pigment.

Thus, although such pigment colorants are prevalent and generally effective at providing color within such thermoplastic fibers, there are certain drawbacks for which improvements have been unavailable.

For example, pigments are notoriously capable of staining fiber manufacturing / extrusion machinery such that control of discolorations within subsequently produced fibers is rather difficult, and the time required to change colors is high.

Also, pigments impart a dulling appearance, a lack of brightness, and a low luster, all believed to be due to the solid nature of such coloring agents.

In addition, pigment size and dispersion limits the processability of small fibers, which are desirable for their improved touch and feel.

However, even with such impressive and beneficial properties and an abundance of polyolefin (such as polypropylene, polyethylene, and the like), which is relatively inexpensive to manufacture and readily available as a petroleum refinery byproduct, such fibers are not widely utilized in products that require fiber and / or yarn colorations therein.

Specifically, although polyesters (such as polyethylene terephthalate, or PET) and polyamides (such as nylons) are generally more expensive to manufacture, such fibers do not exhibit the same unacceptable color disadvantages inherent within polyolefins.

This is due in large part to the difficulties inherent in providing sufficiently bright colorations within such target polyolefin fibers and / or yarns in general.

If certain discrete areas of such target materials do not include any or insufficient amounts of pigments, streaks, uneven colorations, and other aesthetically displeasing results will most likely result.

However, with such a large amount of pigment present within such target fibers and / or yarns comes an inevitable dull appearance as well.

Thus, the visible color provided by the fiber and / or yarn is limited to that portion of the scattered light that is reflected back to the viewer alone.

Furthermore, and just as important, such pigments are extremely difficult to purge from within manufacturing machinery, particularly within fiber extrusion units, such that once a new color is desired for target fiber materials, extensive purging is required for proper cleaning.

Such cleaning is generally quite extensive and complicated since a small amount of residual pigment anywhere within the machinery can discolor any amount of extruded fiber therein.

Thus, utilization of either potentially harmful solvents, in-depth and invasive cleaning procedures throughout the entire unit, and / or wasteful flushing processes that also potentially result in pigment effluent production within wastewater, and the norm rather than the exception for pigment-colored polypropylene methods.

As noted above, in general, polyolefins are an economically superior fiber as compared with other synthetic types (polyesters, nylons, for example); however, its widespread use has been limited due to such issues as this coloration problem.

Thus, although dyes have provided bright colorations in these other types of fibers, extraction and lightfastness issues have, again, severely limited utilization of such coloring agents within polyolefins.

In essence, such soluble coloring agents do not react readily within polyolefin without exhibiting migration and extraction over time.

Within polyolefins, to the contrary, extraction levels are quite high for such dyes and thus unevenness in color, streaking, if not complete loss in color, are typical results.

This problem is further amplified when fabrics made therefrom such dyed polyolefins are subjected to laundering treatments.

Lightfastness (the ability of the target fibers and / or yarns to retain their desired color levels, if not colors at all) are generally unacceptable as well when dyes are utilized without having excessive amounts of protecting agents (UV absorbers, for example) added in addition.

Furthermore, the same machinery staining issues and potential wastewater problems are present with dyes as well, albeit to a lesser degree because of the liquid nature of such coloring agents.

In any event, a certain degree of difficulty still exists within liquid dye processing within polyolefin fiber and / or yam manufacturing (extruding, for example) due to such staining characteristics.

Thus, as for pigments above, efficiency is compromised during fiber manufacture such that any cost benefits of utilizing polyolefin as compared with other synthetic fiber and / or yam types are reduced to a level that is unacceptable for displacement within the fabric industry.

As such, if there is a problem or mismatch between the color masterbatch, there is only limited adjustment available at the fiber manufacturing stage.

This often necessitates re-manufacture of the masterbatch, adding expense and delaying the manufacturing process.

All in all, it is evident that polyolefin has suffered from coloring limitations in the past such that displacement of more expensive fiber types has not been forthcoming and that the standard coloring agents utilized today have neither imparted the necessary brightness, extraction levels, lightfastness properties, and low staining characteristics that appear to be the main obstacles to more widespread use of colored polypropylene fibers within the fabric industry.

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