Claims:We Claim:
1) A compression recovery cellulosic fiber comprising at least one elastomeric polymer integrated in the fiber structure, wherein the elastomeric polymer is selected from a group consisting of natural and synthetic rubbers or thermoplastic elastomers or other polymers having elastomeric properties or combination thereof,
wherein, the amount of elastomeric polymer is in the range of 0.1 to 20 wt % to the total weight of cellulosic fiber.
2) The fiber as claimed in claim 1, wherein the particle size of polymeric particles in the elastomeric polymer is in the range of 100nm to 5µm.
3) A process of producing a compression recovery cellulosic fiber comprises the step of:
(c) adding an emulsion containing at least one elastomeric polymer to a cellulosic dope to provide a homogeneous mix; and
(d) extruding the homogenous mix to obtain the compression recovery cellulosic fiber.
wherein the particle size of the elastomeric polymer is in the range of 100nm to 5micron,
wherein the amount of elastomeric polymer is in the range of 0.1 to 20 wt % to the total weight of cellulosic fiber.
4) The process as claimed in claim 3, wherein the elastomeric polymer is selected from a group consisting of natural and synthetic rubbers or thermoplastic elastomers or other polymers having elastomeric properties or combination thereof.
5) The process as claimed in claim 4, wherein said elastomeric polymer of step (a) is in the form of either emulsion or suspension or the like.
6) The process as claimed in claim 3, wherein the amount of cellulose in cellulosic dope of step (a) is in the range of 8-13 wt%.

7) An article of manufacture having compression recovery characteristics comprising a plurality of fibers as claimed in claims 1-2.

Dated this 08th Day of October 2020
-Digitally Signed-
M. Kisoth
IN/PA-2259
, Description:FIELD OF THE INVENTION
[001] The present invention relates to viscose fibers. In particular, the invention relates to viscose fibers having high compression recovery properties, a process for producing the same, and an article containing the same.
DESCRIPTION OF THE BACKGROUND ART
[002] It is known that compressibility and resilience properties of fabrics are influenced by the fiber and yarn materials. Compressional properties play a vital role in the handle, performance and comfort characteristics of fabrics.
[003] Most widely used fibers for pile fabrics include wool, cellulosic, acrylic, polyamides, polyesters, polypropylene and polyethylene. Compression resilience has been found to be influenced by the type of fibre used. Wool fibres are generally known for good resilience properties and are commonly used in carpets.
[004] However, cotton fibers dominate the terry towel market due to its high water absorption capacity, quick drying and better stacking/bulk properties. Natural fibers such as wool & silk, and synthetic fibers nylon, acrylic, polypropylene, etc. are widely used in the carpet industry. Viscose is used as minor component only, as wool, nylon, polypropylene, acrylic offer better compressive recovery.
[005] Compressibility and resilience properties of pile fabrics are influenced by the pile yarn materials, carpet construction, pile height. Pile density, etc. Pile yarn characteristic is the main parameter that affects resiliency directly. Several studies have been reported on improving the compressibility behavior of fabrics. The fiber fineness has a significant effect on a number of yarn properties including cohesion, evenness, luster, strength, stiffness and compressive recovery.
[006] De Jong et al., (1986) have proposed a three-layer woven-fabric structure a relatively incompressible core layer in contact with much more compressible surface layers on either side.
[007] Compressive recovery or resilience is an important characteristic of the pile fabrics determining their functionality and appearance. In particular, carpets are subjected to short term loads (while walking) or long term loads (while furniture is placed over them) causing them to compress/deform, and are expected to instantaneously bounce-back as soon as the load is removed. The compressive recovery property may deteriorate due to various reasons over a period of time. This deterioration is generally seen as a fuzzy appearance due to loose fibers and fuzz on the carpet surface or as thickness loss.
[008] Terry towels also face compressive loads while drying the body or being spread for sitting on the beach or by the swimming pools. Lack of resiliency, here would manifest in flat piles, lowering area of contact for absorption. Thus, the compressive recovery or resilience, that is the ability to bounce-back to its original form upon the removal of compressive load, is critical to durability of desired performance in these applications.
[009] Use of a fiber aggregate comprising an elastomeric component such as urethane foam, as a cushioning material has also been proposed (see Japanese Patent Laid-Open Publication Nos. 5-161525 and 7-316963). Although urethane foam could be a conceivable cushioning material of an absorbent article, it is unacceptable because of not only high cost incurred but yellowing and smell.
OBJECT OF THE INVENTION
[010] An object of the present invention is to provide regenerated cellulose fibers, more particularly to a new and novel regenerated cellulose fiber having improved compression recovery properties.
[011] An object of the present invention is to provide a process for preparing cellulose fiber having improved compression recovery properties.
SUMMARY OF THE INVENTION
[012] In an aspect, the present invention provides a compression recovery cellulosic fiber comprising at least one elastomeric polymer integrated in the fiber structure, wherein the elastomeric polymer is selected from a group consisting of natural and synthetic rubbers or thermoplastic elastomers or other polymers having elastomeric properties or combination thereof.
[013] In an aspect of the present invention, the amount of elastomeric polymer is in the range of 0.1 to 20 wt % to the total weight of cellulosic fiber.
[014] In another aspect, the present invention provides a process of producing a compression recovery cellulosic fiber comprises the step of:
(a) adding an emulsion containing at least one elastomeric polymer to a cellulosic dope to provide a homogeneous mix; and
(b) extruding the homogenous mix to obtain the compression recovery cellulosic fiber.
BRIEF DESCRIPTION OF THE DRAWINGS
[015] The foregoing summary, as well as the following detailed description of the invention will be better understood when read in conjunction with the appended drawings. For the purpose of assisting in the explanation of the invention, there are shown in the drawings embodiments which are presently preferred and considered illustrative. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown therein. In the drawings:
Figure 1 is a schematic representation of pile fabric.
Figure 2 is a schematic representation of compression and recovery phenomena of a pile fabric.
Figure 3 is scanning electron microscopy images of regular viscose fibers.
Figure 4 is scanning electron microscopy images of compression recovery fibers of the invention.
DESCRIPTION OF THE INVENTION
[016] In describing and claiming the invention, the following terminology will be used in accordance with the definitions set forth below. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. As used herein, each of the following terms has the meaning associated with it in this section. Specific and preferred values listed below for individual process parameters, substituents, and ranges are for illustration only; they do not exclude other defined values or other values falling within the preferred defined ranges.
[017] As used herein, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise.
[018] The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention
[019] As used herein, the terms “comprising” “including,” “having,” “containing,” “involving,” and the like are to be understood to be open-ended, i.e. to mean including but not limited to.
[020] As used herein “compression recovery” denotes the relative recovery of the fibers or extent of ‘bouncing-back’, after the compressive load causing the deformation is removed.
[021] Although viscose staple fibers and filament yarn are used for a wide range of fabrics, their applications in pile fabrics/yarns are limited due to lack of resilience or compressive recovery (CR). Pile fabrics such as carpets, terry or Turkish towels, velvets, corduroy have raised surface consisting of loops or strands of yarn figure 1.
[022] The compression and recovery phenomena of a pile fabric are schematically described in figure 2. The black loops show the initial, un-compressed fabric with the initial height H0. Upon application of a compressive load the fabric deforms (red loops) to a compressed height Hc. The compressed fabric recovers or bounces back to the recovered height (HR), the green loops, after the compressive load is removed. Compressive Recovery (CR) is calculated from following equation,
CR (%) = (HR-HC)/(H0-HC) x 100
Where,
H0= Initial height of fibers
HC= Compressed height of fibers
HR= Recovered height of fibers

[023] Terry towels and carpets made up of viscose exhibit lower compressive recovery than those made from cotton and wool, respectively (Table 1)
Product Constituent fibers CR %
Knotted carpet 100% VSF 51.0
100% Wool 64.9
Tufted carpet 100% VSF 30.4
100% Wool 62.1
Terry towel 80% Cotton/20% VSF 20.9
100% cotton 22.0
Table 1: Compressive recovery properties of terry towels and carpets
[001] Compressive recovery of cotton, wool & viscose fibers are summarized in Table 2.
Fibre Denier Compressive Recovery, (%)

Viscose 6.60 20.0
Wool 11.50 27.8
Viscose 1.29 13.3
Cotton 1.47 25.0
Table 2: Compressive recovery characteristics of fibers
[024] Thus, as indicated by data shown in Table 1 & 2, the viscose fibers and products have lower compressive recovery or resilience than cotton and wool fibers and products, which limits their applications in pile fabrics.
[025] Compressive recovery of viscose fibers can be improved by chemically crosslinking them via post-treatment (Table 3). This requires a separate chemical treatment, drying and curing steps. Additionally, the crosslinking adversely affects elongation and water retention values (WRV) of the fibers (Table 3). As a result, the fibers could have runnability issues during fiber to yarn conversion.
Viscose fiber Denier Dry Tenacity (gpd) Dry Elongation
(%) Water Retention Value (%) Comp. Recovery,
CR (%)


Control 1.16 2.80 20.8 90 11
Crosslinked 1.39 2.65 13.5 39 26
Table 3: Characteristics of control and crosslinked viscose fibers
[026] Considering the above limitations, the invention provides a compression recovery cellulosic fiber comprising at least one elastomeric polymer integrated in the fiber structure.
[027] In another embodiment, the amount of elastomeric polymer is in the range of 0.1 to 20 wt % to the total weight of cellulosic fiber. In another embodiment, the elastomeric polymer is selected from a group consisting of natural and synthetic rubbers or thermoplastic elastomers or other polymers having elastomeric properties or combination thereof.
[028] In another embodiment, the particle size of polymeric particles in the elastomeric polymer is in the range of 100 nm to 5 µm.
[029] In an embodiment, the invention provides a process of producing compression recovery cellulosic fibers comprises the step of:
(a) adding an emulsion containing at least one elastomeric polymer to a cellulosic dope to provide a homogeneous mix; and
(b) extruding the homogenous mix to obtain the compression recovery cellulosic fiber.
[030] In an embodiment, the particle size of the elastomeric polymer is in the range of 100 nm to 5 µm.
[031] In another embodiment, elastomeric polymer may be continuously added to cellulose dope and fibers can be spun. It can also be added to any other stage of dope preparation as well.
[032] In another embodiment, the amount of cellulose in cellulosic dope of step (a) is in the range of 8-13 wt%. In another embodiment, wherein the amount of elastomeric polymer added in step (a) is in the range of 0.1 to 20 wt%.
[033] In an embodiment, the elastomeric polymer is selected from a group consisting of natural and synthetic rubbers or thermoplastic elastomers or other polymers having elastomeric properties or combination thereof.
[034] In an embodiment, the elastomeric polymer is selected from Ethylene-vinyl acetate, silicones, ethylene propylene rubber, epichlorohydrin rubber, styrene-butadiene rubber, nitrile rubber, butyl rubber, polyisoprene, polychloropene, polybutadiene, thermoplastic polyurethanes, etc.
[035] In an embodiment, said elastomeric polymer of step (a) is in the form of either emulsion or suspension or the like.
[036] The invention mentioned here is a simple method of incorporation of an elastomeric polymer in viscose solution and does not require any chemical reaction. The invention overcomes the challenges of crosslinking approach, that is, it does not reduce elongation and water retention value of fibers. It also does not require separate post treatment, drying and curing steps.
[037] In an embodiment, the cellulose dope is extruded through a spinneret known in the art at a predetermined volumetric flow rate into a spin bath containing regeneration media. The fibers extruded into the spin bath were drawn using winders. The obtained fibers are thoroughly washed to remove residual chemicals and subsequently dried to remove access water.
[038] The elastomeric polymers were entrapped into the extruded fibers and would not release or wear off during use or after treatment stages of yarn and fabric making vis-à-vis a conventional coating process.
[039] When fibers are subjected to compressive load/stress they undergo bending. This results in two different kind of stresses being developed within the fiber: compressive and tensile. The internal side of the fiber undergoes compressive stress, while the external side undergoes tensile stress.
[040] The improved compressive recovery cellulose fibers when subjected to compressive load, the elastomeric polymer develops an opposing internal force that helps fibers recover upon removal of load and improves the compressive recovery. Moreover, the elastomeric polymer does not have an adverse impact on elongation of fibers.
[041] The fibres were evaluated for their compression recovery by Bulkometer method where in modified fibers containing elastomeric polymer are compared to control fibers.
WORKING EXAMPLES
[042] The following specific examples are illustrative and explanatory of the present invention but are not to be construed as limiting the scope of the invention.
EXAMPLE 1:
PREPARATION OF CONTROL FIBERS
[043] 250 ml of viscose dope, without any elastomeric polymer, was extruded through a spinneret using conventional process in to a spin bath containing sulphuric acid. Fibres were drawn from spin bath using winders, washed and dried to get 1.26 Denier viscose fibers.
PREPARATION OF COMPRESION RECOVERY FIBERS
MODIFIED FIBER 1
[044] 0.21 g of finely dispersed emulsion of acrylic elastomeric polymer (average particle size =448 nm), having 55% solid content, was mixed thoroughly with 250 g of cellulose dope. This dope containing elastomeric polymer was extruded through a spinneret using conventional process in to a spin bath containing sulphuric acid. Fibres were drawn from spin bath using winders, washed and dried to get fiber of 1.2 Denier.
MODIFIED FIBER 2
[045] 2.33 g of finely dispersed emulsion of acrylic elastomeric polymer (average particle size =454 nm) having 55% solid content, was mixed thoroughly with 400 g of cellulose dope. This dope containing elastomeric polymer was extruded through a spinneret using conventional process in to a spin bath containing sulphuric acid. Fibres were drawn from spin bath using winders, washed and dried to get fiber of 1.42 Denier.
MODIFIED FIBER 3
[046] 6.6 g of finely dispersed emulsion of acrylic elastomeric polymer (average particle size =448 nm) having 55% solid content was mixed thoroughly with 550 g of cellulose dope. This dope containing elastomeric polymer was extruded through a spinneret using conventional process in to a spin bath containing sulphuric acid. Fibres were drawn from spin bath using winders, washed and dried to get fiber of 1.33 Denier.
[047] Figure 3 shows the scanning electron microscopy (SEM) images of control viscose fibers. The multilobed cross section, and serrations on the longitudinal surface are visible.
[048] Figure 4 shows the scanning electron microscopy (SEM) images of modified viscose fibers. The multilobed cross section, and serrations on the longitudinal surface are visible. Additionally, the finely dispersed elastomeric polymer particles are visible in cross section images of the fibers. These images confirm the presence of elastomeric polymer as particles within the fiber bulk.
EXAMPLE 2
EVALUATION OF COMPRESSIVE RECOVERY FIBERS
[049] Compressive recovery denotes the relative recovery of the fibers or extent of ‘bouncing-back’, after the compressive load causing the deformation is removed. Control fibers, without the elastomeric polymer, were also spun for comparison. The compressive recovery of control and modified fibers was measured by Bulkometer method as shown in Table 3. Fibers as were opened by a fiber blender and 10 g of fibers were loosely filled in the Bulkometer cylinder. Initial height (H0) of the fibers was measured, and compressive load was applied to fibers.
[050] Upon application of compressive load, the fibers deformed and their height reduced to compressed height (Hc). For the recovery part, the compressive load was released and fibers bounced back or recovered. The final height after removal of compressive load was HR. The compressive recovery (CR%) of the fibers was calculated from following formula: CR (%) = (HR-HC)/(H0-HC) x 100.
Sample Viscose dope (g) Elastomeric
Polymer
(g) Denier Tenacity (gpd) Elongation (%) CR (%)
Control VSF 250 0 1.26 2.53 24.5 12
Modified Fiber-1 250 0.21 1.42 2.00 26.7 20
Modified Fiber-2 400 2.33 1.33 2.00 22.2 23
Modified Fiber-3 550 6.6 - - - 23
Table 3: Characteristics of control and modified viscose fibers

[051] The compression recovery of fibers of present application has been compared to cotton fibers and bleached cotton fibers. After bleaching cotton fibers show reduction in their compressive recovery as shown in Table 4. The modified fibers also show reduction in compressive recovery but their compressive recovery is comparable to that of bleached cotton.
Sample Compressive Recovery, CR (%)
Cotton 25
Modified Fiber-2 23
Bleached Cotton 17
Bleached Modified Fiber-2 17
Table 4 Resilience of fibers after bleaching

[052] The above description of the present disclosure is provided for the purpose of illustration, and it would be understood by those skilled in the art that various changes and modifications may be made without changing technical conception and essential features of the present disclosure. Thus, it is clear that the above described examples are illustrative in all aspects and do not limit the present disclosure.
ADVANTAGES
[053] The improved compressive recovery viscose fibers when subjected to compressive load recover to original shape upon removal of load. The elastomeric polymer does not have an adverse impact on elongation of fibers.
[054] The elastomeric polymer is incorporated in cellulose dope just before fibers are spun. The method of incorporation of elastomeric polymer in the viscose dope eliminates the need for post treatment of fibers/fabrics. The elastomeric polymer is retained within the fiber bulk.