FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
THE PATENTS RULES, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION METHOD OF PREPARING FLAT CELLULOSE PRODUCT
APPLICANTS ADITYA BIRLA SCIENCE AND TECHNOLOGY COMPANY PVT LTD
of address
Plot No 1 and 1-A/1, Taloja, MIDC, Taluka- Panvel, District Raigad
Maharashtra - 410208
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes this invention and the manner in which it is
to be performed:

FIELD OF THE INVENTION
[1] The invention relates to a cellulose product, in particular relates to a process for preparing cellulose film. The invention further relates specifically to cellulose tape with flat cross section.
BACKGROUND OF THE INVENTION
[2] It is known that flat tapes obtained from thermoplastic polymers have excellent mechanical properties and are widely used in packing of cement, fertilizers, chemicals, plastic granules, grains, etc. in the form of woven bags. However, since these conventional tapes are manufactured from petroleum-based synthetic polymers i.e. polypropylene (PP) and high density polyethylene (HDPE), if discarded in the natural environment after use, they will not decompose.
[3] As these packaging products are obtained from plastics that are not-biodegradable, their usage in packaging results in large quantity of waste ending up in landfill. Improper disposal of the tapes/woven bags made from these non-biodegradable materials also causes the problem of micro-plastic particle generation leading to contamination of soil and water bodies.
[4] The problem of environmental pollution due to plastic packaging can be significantly mitigated by switching from petroleum-based, non-renewable plastics to cellulose – a renewable resources based, bio-degradable material.
[5] The cellulose tape described here is an alternative to PP/HDPE based tape, as it is (1) biodegradable, (2) does not result in micro-plastic particle generation upon its degradation. Manufacturing of flat/ribbon like yarn from cellulosic fibers, to

replace PP/HDPE/PLA tapes, would require (1) manufacturing of staple fibers, (2) spinning of staple fibers into flat/ribbon like continuous yarn and subsequent weaving into flat structure, thereby making it less economically attractive. On the other hand, manufacturing of flat cellulose tapes directly from cellulose solution would make process less complex and economically attractive.
[6] Cellulose can be converted to a film via regeneration of cellulose dope in suitable bath. However, these films are brittle, have low elongation and poor tensile properties, thereby limiting their applications.
SUMMARY OF THE INVENTION
[7] An object of the invention is to provide a method of preparing cellulose product that can be used as a biodegradable, sustainable alternative to conventional packaging.
[8] Another object of the invention is to optimize spinning conditions to improve characteristics of cellulose product.
[9] In accordance with an embodiment of the invention, there is provided a process for preparing a cellulosic product. Cellulose dope is prepared via viscose process. Subsequently, the cellulose dope is extruded through a die having one or more four sided slit/s into a spin bath to obtain cellulose product. In an aspect, said spin bath comprises of sulfuric acid, sodium sulfate and zinc sulfate.
[10] In another aspect, a cellulose dope may be obtained through dissolution of wood pulp in N-methylmorpholine N-oxide solution via lyocell process. Subsequently,

the cellulose dope is extruded through a die having one or more four sided slit/s through an air gap into a spin bath to obtain cellulose product. The spin bath is composed of aqueous solution of N-methylmorpholine N-oxide.
BRIEF DESCRIPTION OF THE DRAWINGS
[11] 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:
[12] Figure 1 shows the cross section profile of cellulose product described in this invention. “W” represents the width and “T” represents the thickness of a cellulose product cross section. The aspect ratio is defined as ratio of width/thickness (w/t).
[13] Figure 2 is scanning electron microscopy image of a cellulose product. The flat/slit-like cross section profile is clearly visible.
[14] Figure 3 is Scanning electron microscopy images showing cross section profiles of (a) conventional viscose staple fibers, (b) cellulose product of this invention.
[15] Figure 4 is a representation of slit profile of the die.

DESCRIPTION OF THE INVENTION
[16] 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.
[17] As used herein, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise.
[18] 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
[19] 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.

[20] As used herein, the term “tenacity” refers to the customary measure of strength of a fibre. Typically, it is defined as the ultimate (breaking) force of the fibre (in gram-force units) divided by the denier. The unit of tenacity is cN/tex (centi Newton per tex) or gram/denier (g/d or gpd).
1 Grams-force/Denier (g/d) = centiNewton/tex (cN/tex) x 0.113
[21] As used herein, the term “denier” is a unit of measure for the linear mass density of a fibre and is defined as the mass in grams per 9000 meters.
[22] As used herein, the term “elongation at break” refers to is the percentage increase in length that a material will achieve before breaking.
[23] In accordance with an embodiment of the invention, there is provided a process for preparing a cellulosic product with flat cross-section comprising the steps of:
a) extruding a cellulose dope through a die having one or more four sided slit/s to obtain cellulose product with flat cross section.
[24] In an embodiment, cellulose dope is obtained by steeping a wood pulp in sodium hydroxide (NaOH) to obtain an alkali cellulose. The obtained alkali cellulose sheets are shredded to obtain light fluffy mass or crumbs and are aged. The aged alkali cellulose crumbs are reacted with carbon disulphide to form cellulose xanthate. The cellulose xanthate is further dissolved in aqueous sodium hydroxide (NaoH), and ripened to obtain a spinning dope solution.

[25] The spinning solution is metered through a die having one or more four sided slit/s into a spin bath. The cellulose product is subsequently stretched in air/spin baths via single or multiple stretching to complete regeneration and impart useful mechanical properties. The cellulose product obtained is washed and dried.
[26] The spin bath comprises of a mixture of sulphuric acid, sodium sulphate and zinc sulphate. In an embodiment, the temperature of spin bath is in range of 45 to 70oC.
[27] In another embodiment cellulose dope in step (a) can be obtained by lyocell process by dissolution of wood pulp in a solution of in N-methylmorpholine N-oxide. Extrusion of cellulose dope involves discharging the dope through a die into an air gap and subsequently into a spin bath to form cellulose products via coagulation of cellulose dope. The cellulose product is subsequently stretched in air/spin bath(s) via single or multiple stretching to complete regeneration and impart useful mechanical properties. The cellulose product obtained is washed and dried. In accordance with an embodiment, dope is spun through a die consisting of one or more four sided slit/s. The spin bath comprises of aqueous NMMO solution
[28] In an embodiment, the concentration of cellulose in dope in step (a) is in the range of 4 to 14%.
[29] The die has one or more four sided slit/s profile through which cellulose solution is extruded through careful control of cellulose solution characteristics, spinning conditions, and stretching conditions to obtain cellulose products.

[30] Figure 4 shows the four-sided slit profile of the die. Where,
w1= width of slit outlet
t1= thickness of slit outlet
w2= width of slit inlet
t2= thickness of slit inlet
L1=Length of straight section of slit
L2=Length of tapered section of slit
V1= cross-sectional velocity at slit outlet (m/s)
V2= cross-sectional velocity at slit inlet (m/s)
[31] The cross-sectional flow uniformity of dope through die is necessary to achieve desired properties. Die’s four sided slit is designed to balance developed shear stress and in-situ velocities to achieve cross-sectional dope flow uniformity. This shear influences physical properties of dope. The slit path’s dimensional ratio controls shear in such a way that at the exit of the die, dope should have flow uniformity along with desired in-situ physical properties to achieve targeted product quality after regeneration & stretching operations. The cross-sectional velocity generated at the inlet & outlet of the four-sided slit/s are maintained such that it overcomes near wall effects throughout the path lengths. The cross-sectional velocity ratio of outlet to inlet of die slit is 2 to 4.
[32] In an embodiment, the process further comprises of stretching the cellulosic product in air/bath to impart mechanical properties. The stretching of cellulosic product at step (e) may be carried out in more than one stage. In an embodiment, the temperature during the stretching is maintained in the range of 25°C to 95°C.
[33] In an embodiment, the cellulose product is cellulose film. In another embodiment, the cellulose product is cellulose tape.

[34] In an embodiment, the method further comprises of forming a cellulose film and splitting it into cellulose tapes with flat cross-section. In an embodiment, slitting of film at step (d) is performed by a tape slitter.
[35] In accordance with an embodiment, cellulose product is drawn from spin bath and washed at 60-100 °C and dried at 100-110 °C.
[36] The resulting flat cellulose tapes have superior mechanical properties. As a result of superior properties the tape can be used for packaging and other applications.
[37] The cellulose products described here are distinct from the conventional yarn from staple fibers or continuous filaments as the cellulose product is a film or tapes that are monofilaments having flat cross-section profile (Figure 1).
WORKING EXAMPLES
[38] 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.
CELLULOSE DOPE
[39] Cellulose dope with different cellulose content (4-14%), and viscosity were prepared via viscose route and lyocell process.
EXAMPLE 1:
[40] Viscose dope having a cellulose concentration of 8.7%, and viscosity 18.0 Pa.s was extruded through a die having one or more four sided slit/s into a spin bath to obtain cellulose product with flat cross section. The spin bath contained a mixture

of sulphuric acid sodium sulphate and zinc sulphate. The spin bath was maintained at a temperature of 60°C. Cellulose product were subsequently stretched in ambient air between the two winders and collected on a drum. Cellulose product were then washed and dried. The cellulose product of 576 Denier having 1.15 gpd tenacity and 2.2% elongation at break was obtained.
EXAMPLE 2:
[41] Viscose dope having a cellulose concentration of 7.7% and viscosity 7.4 Pa.s was extruded through a die having one or more four sided slit/s into a spin bath to obtain cellulose product with flat cross section. The spin bath contained a mixture of sulphuric acid sodium sulphate and zinc sulphate. The spin bath was maintained at a temperature of 60°C. Cellulose product were subsequently stretched in dilute acid bath maintained at 50⁰C between the two winders and collected on a drum. Cellulose product were then washed and dried. The cellulose product of 733 Denier having 1.07 gpd tenacity and 8.3% elongation at break was obtained.
EXAMPLE 3:
[42] Viscose dope having a cellulose concentration of 9.7% and 13.7 Pa.s viscosity was extruded through a die having one or more four sided slit/s into a spin bath to obtain cellulose product with flat cross section. The spin bath contained a mixture of sulphuric acid sodium sulphate and zinc sulphate. The spin bath was maintained at a temperature of 60°C. Cellulose -product were subsequently stretched in ambient air between the two winders and collected on a drum. Cellulose product were then washed and dried. The cellulose product of 718 Denier having 1.51 gpd tenacity and 3.8% elongation at break was obtained.

EXAMPLE 4:
[43] Lyocell dope having a cellulose concentration of 13% and viscosity 1200 Pa.s was extruded through a die having one or more four sided slit/s through an air gap into a spin bath to obtain cellulose product with flat cross section. The spin bath contained aqueous NMMO solution at 10°C. Cellulose product was subsequently stretched in ambient air between the two winders and collected on a drum. Cellulose product of 1127 Denier was obtained after washing and drying.
EXAMPLE 5:
[44] Lyocell dope having a cellulose concentration of 13% and viscosity 1100 Pa.s was extruded through a die having one or more four sided slit/s through an air gap into a spin bath to obtain cellulose product with flat cross section. The spin bath contained aqueous NMMO solution at 10°C. Cellulose product was subsequently stretched in ambient air between the two winders and collected on a drum and washed under stretch. Cellulose product of 760 Denier was obtained.
EXAMPLE 6:
[45] Viscose dope having a cellulose concentration of 9.7% and 13.7 Pa.s viscosity was extruded through a die having one or more four sided slit/s into a spin bath to obtain cellulose product with flat cross section. The spin bath contained a mixture of sulphuric acid sodium sulphate and zinc sulphate. The spin bath was maintained at a temperature of 60°C. Cellulose -product were subsequently stretched in ambient air between the two winders and collected on a drum. Cellulose product were then washed and dried. The cellulose product of (1) 273

denier (2) 634 denier and (3) 944 denier were obtained by varying spinning conditions.
[46] The cellulose tape obtained is characterized by its flat cross section shape and high aspect ratio i.e. the ratio of their width (w) to thickness (t) (Figure 1). Aspect ratio is a critical factor determining the applications and resulting characteristics of flat yarn. Cellulose tape of desired aspect ratio (w/t: 10-1000) can be obtained by suitably selecting the die slit profile and stretch during the spinning process. Typical slit profile dimensions are as follows,

Parameters Range
Slit outlet thickness/width ratio t1/w1 0.0001-0.1
Slit inlet thickness/width ratio t2/w2 0.0001-0.1
Slit length ratio L2/L1 1-10
Cross-sectional velocity at slit outlet to inlet ratio V1/V2 2 – 4
[47] 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.

We Claim:
1) A method for preparing a cellulosic product with flat cross-section comprising the
steps of:
a) extruding a cellulose dope through a die having one or more four sided slit/s to
obtain cellulose product with flat cross section.
wherein the ratio of slit inlet and outlet thickness to width is in the range between 0.0001-0.1, slit length ratio in the range between 1-10 and cross-sectional velocity ratio of outlet to inlet of slit in the range of 2 to 4
2) The method as claimed in claim 1, wherein said cellulose dope of step (a) is prepared by viscose process.
3) The method as claimed in claim 1, wherein said cellulose dope of step (a) is prepared by lyocell process.
4) The method as claimed in claim 1, wherein the concentration of cellulose in cellulose dope is in the range of 4 to 10%.
5) The method as claimed in claim 2, wherein said spin bath comprises of a mixture of sulphuric acid, sodium sulphate and zinc sulphate.
6) The method as claimed in claim 3, wherein said spin bath comprises of N-
methylmorpholine N-oxide solution.
7) The method as claimed in claim 1, wherein temperature of said spin bath is in range of 10 to 70°.
8) The method as claimed in claim 1, wherein the cellulosic product is a cellulose film.
9) The method as claimed in claim 1, wherein the cellulosic product is a cellulose tape.
10) A cellulose product having a flat cross section having denier in the range of 100-
1200.