A method for making a multifilament polyolefin yarn mimicking cotton like yarn as a continuous process on single melt-spin-draw-wind machine and the multifilament polyolefin yarn

Abstract

Invention discloses a method for making polyolefin multifilament yarn mimicking natural cotton on a single melt-draw-spin machine and a multifilament yarn / fiber mimicking natural cotton. The key steps of the method include said feeding the raw material into an extruder to convert them into a fluid melt, passing the said fluid melt through spinneret, where the polymer comes out in form of continuous filaments, cooling the filaments through a blast of cross-flow cold air whereby plurality of filaments is bundled together to form a multifilament yarn, applying spin finish via a nozzle to impart further processability of yarn, heating and stretching the spin finished yarn over a set of rotating heated godets to obtain soft multifilament polyolefin yarns mimicking natural cotton like yarn. The yarn has a stretch ratio of approximately 2 to 6.

Description

[0001] A METHOD FOR MAKING A MULTIFILAMENT POLYOLEFIN YARN MIMICKING COTTON LIKE YARN AS A CONTINUOUS PROCESS ON A SINGLE MELT-SPIN-DRAW- WIND MACHINE AND THE MULTIFILAMENT POLYOLEFIN YARN

[0002] FIELD OF INVENTION:

[0003] The present invention relates to a method for making a soft polyolefin multifilament yarn mimicking like natural cotton and a multifilament soft yarn / fiber mimicking natural cotton made therefrom. The present invention particularly relates to a method of making a polyolefin multifilament yarn that mimics natural cotton and a natural cotton mimicking soft yarn / fiber made therefrom in on single melt spin draw wind machine.

[0004] BACKGROUND:

[0005] With the limited land availability, there is a fight to feed and clothe not only the burgeoning human population but also to meet the ever-increasing feed requirement of the growing animal husbandry industry. Today the cultivable area has been reducing tremendously thereby resulting in lower crop of grown natural fibers used for clothing like cotton / hemp / linen etc. Further, natural fibers of plant and animal origin like linen / silk / cotton etc. are becoming scarce and expensive as climate change is causing reduced yield of usable material

[0006] .In addition, there are growing concerns of environmental pollution as unstructured processing of fibers from natural origin like cotton result in discharge of effluents which are not treated properly and hence lead to pollution. For example, natural fibre processing requires scouring & dyeing with chemicals like acids and alkalis . The effluents are not treated properly resulting in pollution of precious natural resources such ground water pollution. DRAWBACKS IN CURRENTLY AVAILABLE PRODUCTS:

[0007] Currently available polypropylene / olefin multifilament yarns, made as substitutes for natural fibers in coarse counts, have drawback of very high stiffness, not soft and plasticky feel and this results in a very stiff yarn and hence they are not particularly suitable as substitutes for natural fibers in various textile applications for example applications like textile floor coverings, fabrics, upholstery, carpets and rugs and many other applications . While extremely fine natural fibers are used for very fine fabrics suitable for use in direct contact with human body, yet a wider range of applications in textiles use other heavier denier / coarse count of cotton / other natural fibers . The growing population has varied uses of fabrics and textiles and the naturally available fibers are not sufficient to meet the need.

[0008] Cotton Production Trends and analyses show that although India has got first place in the world in cotton acreage with 114.47 lakh hectares area under cotton cultivation i.e., around 36% of world area under cotton cultivation of 314.79 lakh hectares. Approximately 67% of Indian’s cotton is produced on rain-fed areas and 33% on irrigated lands. ( ref min texmin.nic.in)

[0009] India's cotton production has experienced fluctuations over the past two decades. According to the Cotton Association of India (CAI), production peaked at 398 lakh bales in 2013-14 but declined to 294 lakh bales in 2023-24. Despite a steady cultivation area of around 120-125 lakh hectares, productivity remains low due to rainfed conditions in major cotton-growing states like Maharashtra and Telangana.

[0010] Figure 2 shows a visual representation of India's cotton production trend from 2015 to 2025 (reference: Cotton Association of India (CAI), 'Trends of Production, Consumption, Import and Export of Cotton', July 2022). It can be seen that the peak production occurred around 2016-2020, with values above 350 lakh bales. A sharp decline started in 2021, reaching a 15-year low in 2023-24 at 294 lakh bales. 2024-25 shows a slight recovery, but production remains below earlier levels. The furnishing and carpet industry, which relies heavily on cotton yarn and blends, has faced challenges due to reduced availability and rising costs.

[0011] Next, we look at the properties of currently available cotton yarn. The length of the cotton fiber is shown in Table 1. It shows the length of fiber and the fineness of yarn .

[0012] Table 1 - Cotton Fiber length in mm and diameter in microns

[0013] Origin Fiber Length Diameter Microns (mm) (mm)

[0014] Sea-Land Cotton 49-50 0.016 16 Egyptian Cotton 38-44 0.017 17 American Cotton 25.4-38 0.018 18 CIS Cotton 25.4-33 0.02 20 Indian Cotton 20.5- 30 0.021 21 China Cotton 20.5-28 0.021 21

[0015]

[0016] Coarse Pakistan 15.5-25.4 0.021 21

[0017] Further, the cotton classification on the basis of count and equivalent diameter of filament for multifilament yam shows that cotton count of 6’s and below are considered coarse and equivalent denier of around 400 and above in appropriate number of filaments can qualify as coarse yams on the basis of cotton coarse equivalent Further efforts have been made for making polypropylene / olefin multifilament yams as possible substitutes for natural fibre yams by reducing the denier per filament, however such fibers / yams have drawback of very low strength due to their very fine denier / count.

[0018] Besides, the existing yarns have following inherent issues.

[0019] 1. Since these yarns are delicate in nature, therefore require very skillful handling thereby increasing the labour cost dramatically.

[0020] 2. They have low strength and therefore easy to break with a slight pull / lug thereby requiring very smooth weaving structures. 3. Process speed becomes reduced dramatically due to their delicate nature thereby increasing cost of manufacturing and ultimately making the product expensive.

[0021] 4. May require sizing (binding by chemical) to improve the process hence sizing will require to be washed and removed thereby adding process costs and increasing resources.

[0022] Similarly, there are a lot of applications in floorings and furnishings that require the use of substitute of natural fibers in heavy count / denier. The principal requirement of such applications is that the substitute yarn should look and feel like natural fiber.

[0023] A Chinese published Patent application CN102586924A discloses cotton-like polypropylene filament which consist of calcium carbonate functional masterbatches and fiber-grade resin slices, wherein the calcium carbonate functional masterbatches comprise 10 to 25 % of calcium carbonate powder, 5 to 10 % of coupling agent, 10 to 20 % of dispersing agent and 45 to 75 % of carrier resin. A processing technology comprises two steps of preparing the calcium carbonate functional masterbatches and spinning. The invention has the advantages that (a) on the premise of not changing physicochemical characteristics of polypropylene fibers, the moisture absorption and flexibility of the polypropylene fibers are effectively improved fundamentally, closed-fit wearing comfort of polypropylene fiber, fabrics is improved, and the requirement on cotton-like polypropylene filaments is met. Hence the said invention is addressing the issue of poor hygroscopicity of polypropylene fiber, when making underwear, sportswear and other clothing that directly contact the skin or wear close to the skin.

[0024] Further, the textile articles for human clothing applications are generally made in manmade fibers having deniers of less than 1 denier (microfiber) to upto 100 denier for clothing worn next to skin example ( human hair is around 20 denier only and therefor soft ). The lower deniers yams can be textured in secondary process to develop softness which is desired feel for clothing fit to be in contact with the human skin. However, the fibers / yams produced by the process disclosed therein are not suitable for applications like furnishing and upholstery where water plays a damaging role due to their hygroscopic nature. Further they are not suitable for such purposes due to low denier, as for upholstery and carpeting much higher denier yam is required in soft feel. Moreover, due to its hygroscopic nature, it is prone to be mould growth and fungal and bacterial issues. Hygroscopic nature of such yams also opens up the yarn to getting stained which is highly undesirable in case of fabrics that cannot be washed so easily like upholstery and furnishings etc.

[0025] Also, this prior art uses multiple operation stages & machines involving major manpower & capital intensive. Hence there is a need to develop a single machine process and a soft cotton like yam made using such process which provides the high quality of desired properties of colour, lustre, and cotton like natural soft feel and at the same time overcome the undesirable properties of natural fibres, such as Water absorbency(hygroscopic), low resistance to acid and alkalis, low abrasion resistance, pilling, rough hand and feel when made in coarse count / high denier, stainability, resistant to pest attacks, mould, fungal and bacterial growth etc.

[0026] THE OBJECTS OF THE INVENTION:

[0027] The objective of the present invention is to provide a method for making a polyolefin multifilament yam mimicking natural cotton like yarn feel in coarse counts on single machine in single process

[0028] Yet another object of the present invention is to provide a polyolefin multifilament yam mimicking natural cotton like yarns / fibres that incorporate the high quality of properties of colour, lustre, soft look and feel like natural fiber and overcome the undesirable properties of natural fibres. The mimicked cotton olefin yarns are made in heavier denier / coarser counts like denier having average thickness of each filament to be over 18 to 21 microns similar to coarse cotton based on fiber length and diameter and the suitable application like carpet and upholstery etc. carpet cotton fiber (refer Table 1 for cotton fiber length and diameter in microns). Inventive polyolefin yarn of the present invention has a dpf up to 50.

[0029] In general cotton count of 6’s and below are considered coarse and are equivalent denier of around 800 and above in appropriate number of filaments can qualify as coarse yarns for multifilament yarns on the basis of cotton coarse equivalent

[0030] SUMMARY OF THE INVENTION:

[0031] The present invention relates to a method or process of making a polyolefin multifilament yam mimicking like natural cotton yarn on a single melt-spin-draw winding machine. The said process comprises the following steps (see Figure 1):

[0032] 1. Feeding the granules of polyolefins and other material recipe into an extruder wherein the extruder has a heating chamber and a screw / barrel arrangement and where the granules are heated and moved forward under pressure to convert them into a fluid melt, 2. Passing the said fluid melt through spinneret, which is a shower type die, where the polymer comes out in form of continuous filaments, 3. Cooling the filaments through a blast of cross-flow cold air to make the melt solid and suitable for a continuous yarn formation wherein plurality of filaments is bundled together to form a multifilament yam, 4. Applying spin finish via a nozzle to impart further processability of yarn

[0033] 5. Heating and stretching the said spin finished yarn through a series of godet rolls wherein multifilament yarns are kept soft and wherein the heating can be done by heated godets and stretching is done by changing the speed of the godet system, 6. Finally winding such processed multifilament yam polyolefin yarns mimicking natural cotton like yam on bobbins for end use applications.

[0034] The process disclosed herein has been carried out on a single melt spin draw winding machine to make the yarn disclosed herein.

[0035] LIST OF FIGURES:

[0036] Figure 1 shows a flow diagram of the process of the present invention

[0037] Figure 2 shows cotton production in India over a period between 2015 and 2023 Figure 3 shows a chart of Feel Score Distribution by Profession and Yam Type Figure 4 shows a conventional melt-spin-draw apparatus for inventive process

[0038] DETAILED DESCRIPTION OF THE INVENTION:

[0039] Figure 1 of the accompanying drawing illustrates various steps of the process of the present invention in flow diagram. As per the flow diagram as shown in Figure 1, the melt spin draw winding process comprises of the following steps.

[0040] Raw material comprising polymeric material fed via a hopper into the Extrusion system (2) comprising screw -barrel- die system and extruding it under heat and pressure to form fine filaments. These filaments are unstable and need to be cooled via the Quench Cooling process (3) where cross flow air controlled for temperature and flow is fed perpendicular to the spin line (90 degrees) to the filament spin line (in this case air is fed horizontally as the filament is extruded vertically). Further the quenched yam is subjected to a Spin Finish Application (4) and Stretching (5), following which the finished mimicked cotton like yarn is wound on spools. A detailed description of various parameters of the present novel and inventive process / method is given below.

[0041] Step 1: Selecting proper raw materials:

[0042] a) Polyolefin: 80% to 98% of total raw material mixture w / w basis are polyolefin polymers which can be homopolymers, copolymers and / or reprocessed polyolefin polymer (RPP) or a blend of the same. RPP content maybe upto 50% of total raw material mixture w / w basis Any commercially available known polyolefin polymers are used preferably polypropylene used. In particular, Polyolefin polymers with Melt Flow Index (MFI) in the range of MFI between 8 and 35 are used to achieve varied level of hand feel in the yarn. In the present invention, we have used materials with different MFI and have been able to achieve similar desired results. The materials used were from different reputed manufacturers of Olefin polymers. The preferred polymer range is from 8 MFI to 25 MFI.

[0043] b) Additives and adjuvants: PP / PE based hindered amine light stabilizers (HALS) type UV agent in granules form are added as additive in the range of 0% to 12%w / w for providing UV protection for outdoor use. In specific HALS 20 type UV protection agents in PP polymeric base as supplied by Manufacturers have been used to the extent of 4% by weight of base polymer. Need base other additives and adjuvants like flame retardants, anti-fungal agent and others may be used upto 15%.

[0044] c) Colour Additives: PP / PE based colour and Masterbatch are added as per requirement between upto 15% w / w for imparting colour and delustering agent as per requirement of the end use.

[0045] d) Spin finish oil: A spin finish oil comprising of fatty acid esters and antistat additives in water-based solvent is used here to give an ultimate oil pickup between 1% - 8% w / w on the yarn (applied in step 4). Step 2. Extrusion:

[0046] In polymer extrusion, the raw material is gravity fed into the feed throat of the extruder where a rotating screw pushes the material. The screw is housed in a barrel which is heated. The heating temperature of the barrel is largely dependent of the Melt flow characteristic of the polymer. Heat is generally provided in multiple zones over the length of the barrel. The temperatures are set on the basis of the melt characteristics of the polymer. For example, in the inventive yarn a polyolefin polymer with MFI of 13 has been processed on an extruder with multiple heating zones, present machine (see Figure 4) had three zones in the extruder followed by a melt delivery pump and a die housing the spinneret. When processed in the machine with three zone heating in extruder followed by a melt pump and die, the temperature ranges are in the area range of 180 to 210°C in zone one going up to 240 °C in the second zone and in third zone of the barrel with temperature going up to the 270°C and up to 280 °C in the melt pump and die housing the spinnerets. The temperatures are so maintained that the raw material in solid granular form is changed into a melt which can be extruded through spinneret. The pressure of the melt is developed due the screw profile and the pressure is maintained in the range of 25 bar to 90 bar.

[0047] Step 3. Quench Cooling:

[0048] In man-made filament yarn from polymer, the processing quench temperature plays a very critical role in changing the morphology of the extruded yam. Sudden cooling results in development of crystals which is not suitable for certain applications whereas inadequate cooling results in yarn with undesirable properties such as very high elongation and residual shrinkage. In general, for melt spun polymers, the process of quenching is achieved by either purging the melt in cold water or by passing cold air from behind or around the filaments to cool them. The process of Melt spin draw winding of Multifilament yarn is generally having an air-cooled quench system where cooled air is blown at a controlled speed from behind the filaments. The rate of cooling is dependent on the contact temperature and time of the air with the continuously moving filament. As the filament drops down from the spinnerette, it is encountered by a cross flow of cold air. This cools the molten filament into a solid form. Although the temperature of cool air can be maintained between 5 and 20 °C, however, the for the purpose of the present invention the quench temperature range is kept in the range of 10 to 20 °C for quench air. A quench temperature in the range of 12 to 15 °C has been found to be preferably more suitable. A cross-air quench flow rate of 0.7 m / s -1.8 m / s is generally used. In the present invention, the quench flow rate is maintained between 0.85 and 1.2 m / s.

[0049] Step 4: Applying Spin Finish: In the present invention a spin finish oil as is commonly available for processing of multi filament yarns, comprising of fatty acid esters and process aid additives is used. Spin finish helps in further processing of yams over the godets. The spin finish changes the contact behaviour between the yam and the godet surface. The composition of spin finish and the quantity determine the heat transfer rate, grip / slip over godet (abrasion or lack thereof), uniformity of stretch, discharge of static electricity etc. If spin finish is not applied uniformly then the filaments will have different uptake of temperature and will also have different slip on the godets. There will be a vast difference in the denier, elongation, strength etc. in the yarn. Spin finish can be applied by passing the yam over rollers as in lick roll type of spin finish application or by passing the yarn through spin finish applicator nozzles which are v shaped guides with holes from which spin finish is pushed through. However, we find that the v shaped ceramic guide-based system is better than the lick roll system. Spin finish is applied by passing the yarn over two v shaped ceramic guides having a hole in the back side through which the spin finish oil is delivered. These Ceramic guides are in line of yarn extrusion and are placed opposite each other to ensure uniform application of spin finish to all filaments. The quantity of spin finish oil being pushed through the hole is controlled by means of spin finish metering pump driven by a motor controlled by an inverter drive enabling precise output control. This spin finish is as a ratio of the output of yam from the extruder. General spin finish between 1% to 20% w / w can be used in neat or diluted form. However, in the present invention, spin finish in the range of 2% to 6% in neat as well as in mixture blended with water is preferable. The uniformity of application of spin finish and the quantity of spin finish determines the uniformity of the final yam properties in each of the multiple filaments.

[0050] Step 5: Stretching with different parameters of temperature and speed. Yam fresh after extrusion, quench cooling and spin finish application (of step 2, followed by step3 and 4) has very low / no polymer orientation. The yam needs to be further processed by heating and stretching to align the polymer molecules in the direction of the length of the yarn. This alignment helps to develop technical properties of the yam such as strength, elongation and shrinkage etc. The passing of yam over rotating heated rollers (godets), changes the temperature of the yam and the differential speed between the godet changes the diameter of the yarn in the case of stretch / relaxation. The temperature and speed of these rotating rollers is controlled through invertors drives and microprocessor-based controls for ease of fine settings. The process of stretching also causes a change in the diameter (resulting in the change of denier) of the yarn. The process of stretching over heated rolls provides dual purpose of heat and stretch at the same time which facilitates the stretching as the yarn becomes more pliable, allowing the molecules to realign, which in turn leads to stretching and consequently reduction in yarn diameter (change in denier). The speeds of the godets are progressively increased / reduced to provide a stretch / relaxation to the yarn passing over these godets. Common stretch ratios for PP multifilament yarns are between 4 to 12. However, to obtain the mimicked cotton like soft multifilament yarns of the present invention, the stretch ratio is kept below the common stretch ranges between 2 and 6 by controlling the speed and temperature of the godets in the stretching zone.

[0051] As mentioned above, controlled heating and cooling is essential for producing high quality multifilament soft polyolefin yarns mimicking natural cotton like yarn of the present invention. The temperature range for heating the yams is set so that the yarn over godet contact stay well below the melting point of the polymer. In the inventive process, godet temperature and speed settings for godet rolls are in the range of unheated feed roll at 250 to 1250 mpm followed by first godet at 75 to 95 °C and first godet roll delivering a yarn speed of 260 to 1260 mpm and further progressing up to 90 to 120°C on subsequent rolls going up to 135 degrees for intermediate roll at 520 to 1520 meters per minute (mpm) and the maximum speed of 580 to 1580 meters per minute with roll temperature of 110 to 140 °C and thereafter cooling and relaxation temperature of 100 °C at speed of 565 to 1565 meters per minute to a final winding speed of 570 to 1570 meters per minute, giving a stretch ratio of approx. 2 to 6. Depending on the melt spin draw wind machine configuration multiple drawing zone may vary from 2 to 7 steps / stages. Hence the godet speed and contact temperatures are so adjusted and controlled so as to be able to achieve a physical change in the yarn processed to obtain the desired technical characteristics comprising strength, elongation, and the soft hand which mimics cotton like yam.

[0052] Yam suitable for carpet and upholstery use is generally above 400 denier.

[0053] By controlling the process parameters of quenching, spin finish, contact time and temperature during stretch the present invention has been able to achieve and provide soft multifilament yarn maintaining a level of surface feel that mimics soft polyolefin multifilament yam to natural cotton like yam of the present invention which is available as a continuous filament yarn.

[0054] It is evident from the foregoing that the present invention has the following embodiments.

[0055] The principal embodiment of the present invention discloses a method for making a multifilament polyolefin yam mimicking cotton like yarn, said method comprising the following steps: a. selecting raw materials including polyolefin blend, UV agent additives, colour additives, and spin finish oil;

[0056] b. extruding the raw materials through an extruder having a rotating screw inside a barrel, a melt pump and a die housing a set of spinnerets, wherein said raw materials pass through said extruder under predetermined temperature and pressure to produce extruded yarn;

[0057] c. quench cooling the extruded yam using blown air of a temperature between 5 and 20°C and at a cross-air flow rate of 0.7 to 1.1 m / s;

[0058] d. applying spin finish to the quenched yam;

[0059] e. stretching the spin finished yam over a set of rotating heated godets;

[0060] Another embodiment of the present invention discloses a method as disclosed in the principal embodiment wherein said raw materials comprise polyolefin granules blend in an amount of 80% to 98% w / w which may content blend of virgin polyolefin 30 to 95% and RPP 0 to 50% and Copolymer 0 to 20%; PP / PE based hindered amine light stabilizers in an amount between 0% to 12%, and colour additives in an amount of 0% to 15% w / w, and fatty acid esters and antistat additives in water based solvent in an amount of 1% to 2% w / w basis.

[0061] A further embodiment discloses a method as disclosed in the previous embodiment wherein said polyolefins are in the preferably in form of homopolymers with a melt flow index between 8 and 35, wherein homopolymers / copolymer of different melt flow indexes may be blended to get desired MFI value.

[0062] Yet another embodiment discloses a method as disclosed in the principal embodiment wherein heat is generally provided in multiple zones provided over the length of the barrel, and wherein the temperatures are in the area range of 210°C in zone one, going up to 240 °C in second zone and in the third zone of the barrel, going up to the 250 °C and up to 270 °C in the melt pump and the said die housing the spinnerets, and wherein the pressure of the melt within the barrel is maintained in the range of 25 bar to 90 bar.

[0063] Another embodiment discloses a method as disclosed in the principal embodiment wherein the temperature of the blown air is maintained between 8 to 20 °C with the blown air being released at a cross-air flow rate of 0.85 and 0.95 m / s.

[0064] A further embodiment discloses a method as disclosed in the principal embodiment wherein said spin finish is applied uniformly by passing the yarn over rollers, said roller being of the lick roll type.

[0065] Yet another embodiment discloses a method as disclosed in the principal embodiment wherein said spin finish is applied by passing the yarn through two v shaped ceramic guides having a hole in the back side through which the spin finish oil is delivered, and wherein said ceramic guides are in line of yarn extrusion and are placed opposite each other.

[0066] Another embodiment discloses a method as disclosed in the principal embodiment wherein the amount of spin finish oil is in the range of 1% to 6% w / w in mixture form blended with water upto 80% w / w as well as in neat form.

[0067] Another embodiment discloses a method as disclosed in the principal embodiment wherein the stretch ratio is in the range of 2 to 6.

[0068] Another embodiment discloses a method as disclosed in the principal embodiment wherein the temperature and speed settings for godet rolls are in the range of unheated feed roll at 150 to 1250 mpm followed by first godet at 75 to 95 °C and first godet roll delivering a yam speed of 160 to 1260 mpm and further progressing up to 90 to 120 °C on subsequent rolls going up to 135°C for intermediate roll at 320 to 1520 meters per minute (mpm) and the maximum speed of 380 to 1580 meters per minute with roll temperature of 110 to 140 °C and thereafter cooling and relaxation temperature up to 100 °C at speed of 465 to 1565 meters per minute to a final winding speed of 470 to 1570 meters per minute, giving a stretch ratio of approximately 2 to 6.

[0069] The present invention discloses a judicious blend of the process parameters and ingredients to arrive at the tactile hardness / softness and hand / feel character of the yarn, mainly decided by feel study of the yam

[0070] A blind feel study of softness was carried out for over one hundred participants to compare the feel of three yarn types. Polyester yarn is the least preferred, with no participants rating it highest. Average feel scores on scale of 1-10 were tabulated. Referring to Table 2 and Table 3 we find Olefin / PP soft cotton-like yarn scores highest and is clearly the most preferred in terms of feel. Olefin / PP soft yam scores higher than both cotton and polyester in average feel scores and rating and Olefin PP soft Yarn is the top choice for 72% of participants.

[0071] Table 2: Average Feel Scores (1-10 scale)

[0072] Yarn Type Average Score

[0073] Olefin / PP Soft Yarn 8.49

[0074] Cotton Yarn 6.83

[0075] Polyester Yam 4.83

[0076]

[0077] Table 3: Preference Percentages

[0078] Yarn Type Preferred by (%)

[0079] Olefin / PP Soft Yarn 72%

[0080] Cotton Yarn 12%

[0081] Polyester Yarn 0%

[0082]

[0083] Further the results were analysed with respect to professions and choice. For example, we observe that students and working professionals tend to rate Olefin / PP soft yarn higher than others (refer the chart shown in Figure 3). An Anova analysis showed an F-statistic: 911.47 and a P-value: 1.76x10 ~127. This extremely low p value indicates a stsitscally significant difference in fell scores among the yarn type. Assumptions were checked using Shapiro - Wilk Test for Normality, Homogeneity of Variances (Levene’s Test), etc. Despite minor deviations from normality in minor subgroups, the robust Welch’s ANOVA confirms that Olefin / PP Soft Yam significantly outperforms cotton and Polyester in perceived feel Refer tables 2, 3, 4.

[0084] Table 4: Robust ANOVA (Welch’s ANOVA)

[0085] Source Sum of Squares df F-value p-value

[0086] Yam Type 647.84 2.0 907.93 2.89 x 10127Residual 105.96 297 — —

[0087]

[0088] It should be noted that any fabric made from such inventive yams / fibers made from such yarns may be, without limitation, tufted, woven, knit, non-woven, inlaid scrim, any combination thereof, and the like. Such yams can also be cut into staple fiber lengths and used as such for nonwoven application like felting or further processed into staple fibre yarns and put to various end uses . Additionally, such fabrics may include yarns and fibers other than the inventive olefin / polypropylene yams / fibers, including, without limitation, natural fibers, such as cotton, wool, abaca, hemp, ramie, and the like; synthetic fibers, such as polyesters, polyamides, polyaramids, other polyolefins (including non-low-shrink polypropylene), polylactic acids, and the like; inorganic fibers such as glass, boron-containing fibers, metallic yams and fibers, and the like; and any blends thereof.

[0089] The yarn of the invention is now explained using the following examples. Example 1: Olefin Melt spin draw winding example for soft Mimic cotton like inventive yarn

[0090] In this Example according to the melt spin draw winding process, Inventive soft Olefin yarns are made with raw material (step 1 of the process of invention as described in the foregoing sections) comprising 70% Polypropylene Homopolymer, 26% RPP, 2% copolymer, 2.0% of Additive MB for UV Stabilization. The raw material such processed in Extrusion system maintaining a melt pressure between 25-35 bar (step 2 of the process of invention as described in the foregoing sections) and extruded Multifilament Olefin Yam is subject to Quench Cooling (step 3 of the process of invention as described in the foregoing sections) cooled in a quench chamber with Cross flow air system having an air temperature of 12 °C and a flow rate of 0.85 - 0.95 m / s. Each bundle of Olefin Multifilament Yam is subject to Spin Finish application (step 4 of the process of invention as described in the foregoing sections) by passing over two oil flow nozzles fed by a metered oil delivery device. The oil pump delivers around 4% oil on yam w / w basis. Further the as such extruded Olefin Multifilament Yam is received on a take-up roll which is rotating at a yarn delivery speed of 320 mpm (meters per minute). At this stage 4 such bundles of yarn are collated together is subject to drawing and further stretching. The Multifilament Olefin Yarn is then subjected to unidirectional stretching zone (step 5 of the process of invention as described in the foregoing sections) by entering into the first set of godet and separator roll. The first godet maintained at a temperature of 85 °C and a rotation speed to give a yarn delivery speed of 340 mpm. This is followed by yam moving on to the second set of godet and separator rolls where the speed is maintained at 370 mpm and the temperature is 115 °C. The yarn then moves to the third set of godet rotating to give a yam delivery speed of 450 mpm and a temperature of 125 °C. The yam then moves on to the fourth set of godet at yarn delivery speed of 490 mpm and temperature of 140 °C. To give mild annealing, the yam is further transported to the next set of godet operating at speed of between 520 and 560 mpm more so at speed of 530 mpm maintaining a godet surface temperature of 120 °C. The yarn then enters a sixth set of godet rotating at a yam delivery speed of 510 mpm. The yam so produced is wound in cross wound in winding device at a speed of 520 mpm (step 6 of the process of invention).

[0091] The Multifilament Olefin Yarn disclosed in the foregoing example which has been obtained using the process disclosed herein has the following properties:

[0092] Denier - 8000

[0093] DPF :20.40

[0094] Average filament Thickness: 58 microns

[0095] Breaking tenacity: 1.9 gpd

[0096] Elongation at break: 22%

[0097] Feel / Hand: Soft hand and feel

[0098] Example 2: In yet another instance experiment to process mimic cotton yam inventive are made with raw material (step 1 of the process of invention as described in the foregoing sections) comprising 96 % Polypropylene Homopolymer, 4.0 % of Additive MB for UV Stabilization. The raw material such processed in Extrusion system maintaining a melt pressure between 65-70 bar (step 2 of the process of invention as described in the foregoing sections) and extruded Multifilament Olefin Yarn is subject to Quench Cooling (step 3 of the process of invention as described in the foregoing sections) cooled in a quench chamber with Cross flow air system having an air temperature of 12 °C and a flow rate of 0.85-0.95 m / s. Each bundle of Olefin Multifilament Yarn is subject to Spin Finish application (step 4 of the process of invention as described in the foregoing sections) by passing over two oil flow nozzles fed by a metered oil delivery device. The oil pump delivers around 2.5% oil on yarn w / w basis. Further the as such extruded Olefin Multifilament Yarn is received on a take-up roll which is rotating at a yarn delivery speed of 500 mpm (meters per minute). At this stage 4 such bundles of yam are collated together is subject to drawing and further stretching. The Multifilament Olefin Yam is then subjected to unidirectional stretching zone (step 5 of the process of invention as described in the foregoing sections) by entering into the first set of godet and separator roll. The first godet maintained at a temperature of 95 °C and a rotation speed to give a yarn delivery speed of 630 mpm. This is followed by yam moving on to the second set of godet and separator rolls where the speed is maintained at 1370 mpm and the temperature is 125 °C. The yarn then moves to the third set of godet rotating to give a yarn delivery speed of 1420 mpm and a temperature of 145 °C. The yarn then moves on to the fourth set of godet at yarn delivery speed of 1490 mpm and temperature of 135 °C. To give mild annealing, the yam is further transported to the next set of godet operating at speed of between 1520 and 1550 mpm more so at speed of 1530 mpm maintaining a godet surface temperature of 120 °C. The yarn then enters a sixth godet which is unheated and rotating to give a yarn speed of 1510 mpm

[0099] The yarn so produced is wound in cross wound in winding device at a speed of 1520 mpm (step 6 of the process of invention).

[0100] The Multifilament Olefin Yam obtained have the following properties:

[0101] Denier: 2400; DPF: 12.24; Average filament thickness: 45 microns Tenacity Fmax: 3.5 gpd; Elongation at Fmax: 25%

[0102] Hand / Feel: Soft cotton like feel

[0103] The foregoing examples are only illustrative and do not limit the full of the invention disclosed here.

[0104] Benefits of the present invention:

[0105] The following are some of the most important and key benefits which are accrued from the present invention:

[0106] a. The present invention provides, Soft Continuous multifilament yarns, made from manmade material in a continuous process on a single melt-spin-draw winding machine, which have a feel like cotton and which do not require further processing for use in textile applications like furnishing and carpets etc. The continuous multifilament yam is unlike cotton which is Naturally sourced which requires many stages of processing before the fiber can be used further for textile applications

[0107] b. The product of the present invention is a continuous filament form of large length of several kilometers and has colour and shine (dullness) like natural fibre albeit the colour and shine are more durable and environmentally friendly than dyed fibers of natural origin. It may be pertinent to note that process of dying / colouring of natural fibers is very resource intensive and if not manged well is highly polluting.

[0108] c. The yams and fibers of the present invention can be used as made without further intermediate process and suitable replacement of other natural fibers like cotton, jute, sisal, hemp etc .

[0109] d. The product of the present invention is more durable than the cotton and other natural fibers of plant origin.

Claims

Claims1. A method for making a soft multifilament polyolefin yarn mimicking cotton like yam characterised in that said method is a continuous process carried out on a single melt-spin-draw wind machine, said method comprising the following steps:a. selecting raw materials including polyolefin polymers, UV agent additives and adjuvants, colour additives, and spin finish oil; b. extruding the raw materials through an extruder having a rotating screw inside a barrel, a melt pump and a die housing a set of spinnerets, wherein said raw materials pass through said extruder under predetermined temperature and pressure to produce extruded yarn;c. quench cooling the extruded yam using blown air of a temperature between 5 and 20 °C and at a cross-air flow rate of 0.7 to 1.1 m / s; d. applying spin finish to the quenched yarn;e. stretching the spin finished yarn over a set of rotating heated godets to obtain soft multifilament polyolefin yarns mimicking natural cotton like yarn.

2. The method as claimed in claim 1 wherein said raw materials comprise polyolefin granules in an amount of 80% to 98% w / w need base PP / PE based hindered amine light stabilizers in an amount between 0% to 12%, and need base colour additives and other classical adjuvants like fire retardants etc in an amount of 0% to 15% w / w, and fatty acid esters and antistat additives in water based solvent in an amount of 1% to 6% w / w basis.

3. The method as claimed in claim 2 wherein said polyolefins are in the form of homopolymers / copolymers with a melt flow index between 8 and 35, wherein homopolymers of different melt flow indexes are used.

4. The method as claimed in claim 1 wherein heat is generally provided in multiple zones over the length of the barrel, and wherein the temperatures are in the area range 180 °C going up to the 270 °C and up to 280 °C in the melt pump and the said die housing the spinnerets, and wherein the pressure of the melt within the barrel is maintained in the range of 25 bar to 90 bar.

5. The method as claimed in claim 1 wherein the temperature of the blown air is maintained between 10 to 20°C with the blown air being released at a crossair flow rate of 0.85 and 0.95 m / s.

6. The method in claim 1 wherein said spin finish is applied using a lick roll system.

7. The method as claimed in claim 1, wherein said spin finish is applied by passing the yam through two v shaped ceramic guides having a hole in the back side through which the spin finish oil is delivered, and wherein said ceramic guides are in line of yam extrusion and are placed opposite each other.

8. The method as claimed in claim 1, wherein the amount of spin finish oil is in the range of 1% to 6% w / w in neat form as well as in mixture form blended with water.

9. The method as claimed in claim 1 wherein the stretch ratio is between 2 to 6.

10. The method as claimed in claim 1, wherein godet temperature and speed settings for godet rolls are in the range of unheated feed roll at 150 to 1250 mpm followed by first godet at 75 to 95 °C and first godet roll delivering a yarn speed of 160 to 1260 mpm and further progressing up to 90 to 120 °C on subsequent rolls going up to 135°C for intermediate roll at 320 to 1520 meters per minute (mpm) and the maximum speed of 380 to 1580 meters perminute with roll temperature of 110 to 140 °C and thereafter cooling and relaxation temperature upto 100 °C at speed of 465 to 1565 meters per minute to a final winding speed of 470 to 1570 meters per minute, giving a stretch ratio of approx. 2 to 6.

11. The method as claimed in claim 1, wherein 0% to 50% of total raw material mixture w / w is a blend of reprocessed polyolefin polymer.

12. A soft multifilament polyolefin yarn mimicking cotton like yarn, surface feel that mimics polyolefin multifilament yam to natural cotton like yarn.

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