Spinning Article

This article presents experimental data concerning variation of the physico-mechanical properties of cotton and viscose fabrics cross-linked with a modified product on the basis of dimethyloldihydroxy ethylenecarbamide in the presence of different catalysts. The basic aim is to decrease the shrinkage of the fabric, which is why relatively low concentrations of the cross-linking agent are used. The results obtained are of definite interest, verifying the high catalytic activity of the mixed catalyst MgCl2 – citric acid – tartaric acid.
Key words: cross-linking agents, shrinkage finish, crease-resist finish, cross-linking cata­lysts, cotton, viscose.

Introduction
The textile materials are usually under significant lengthwise stress during the refinement processes. This results in con­siderable shrinkage during subsequent use because of the effect of the corre­sponding relaxation forces. Mechanical and chemical interventions provide pos­sibilities for stabilising the dimensions of the cellulose textile materials. The chemical method leading to cross-linking of the cellulose macromolecules through the introduction of different products is one of the most widely used. In this way, the current state of the fabric is fixed and subsequent shrinkage is hindered. The cross-linking is usually achieved by the application of chemical compounds which are applied in the crease-resist fin­ish of the fabric. The treatment proceeds in the presence of lower concentrations of the additive when shrinkage alone, and not creasing decrease, is required. It is known that a number of parallel reac­tions leading to an essential decrease in cloth stability [1,2] run simultaneously with the main reaction of cross-linking the cellulose macromolecules. When the cross-linking agent and the correspond­ing procedure are not correctly chosen, the degree of whiteness is significantly changed [3,4].
The aim of the present investigations is to find out whether it is possible to decrease the shrinkage of cotton and viscose fab­rics by using a cross-linking agent of the dimethyloldihydroxy ethylenecarbamide (DMDHEC) type in the presence of dif­ferent catalysts, and to follow the cross-linking effect on some of these materials’ properties.
Experimental
The experiments were carried out with the following materials:
§ 100% cotton fabric with a surface
mass of 154 g m^-2, leno weaving, a
linear density of the basic threads of
32 tex, a linear density of weft threads
23 tex, a warp density of 270 cm^-1, a
weft density of 220 cm^-1;
§ 100% viscose crêpe fabric with a surface mass of 114 g m^-2, leno weaving, a linear density of the basic threads of 14 tex, a linear density of weft threads 14 tex, a warp density of 360 cm^-1, a weft density of 270 cm^-1;
§ dimethyloldihydroxy ethylenecarbamide (DMDHEC) used as a cross-linking agent:

§ catalyst 1: melamin, an acidic donor
used in carbamide cross-linking;
§ catalyst 2: MgCl2;
§ catalyst 3: MgCl2 – citric acid – tartaric
acid (1:1:1);
§ catalyst 4: citric acid – tartaric acid (1:1).
All the textile fabrics investigated were treated by the dry cross-linking method, which consists in:
§ single soaking of foulard in an aque‑
ous solution of the cross-linking agent at a temperature of 20°C, and a squeezing degree of 80%;
§ drying at 130°C for 5 min;
§ thermal treatment at 150°C for 4 min.
The concentrations of the cross-linking agent used are within the range of 5 to 30 g l^-1. It is important to note that in case of creasing decrease, the concentrations
used usually range between 30 g ^l-1 and 50 g l^-1. The catalyst’s quantity amounts to 30% of that of the cross-linking agent. In order to outline the effect of the cross-linking agent and that of the catalyst on the properties of the fabrics treated, this procedure was followed in all the experi­ments carried out.
Results and Discussion
The effectiveness of the cross-linking is evaluated by the total angle of relaxation which follows the creasing, according to BSS 9589-72 (the Somer method), by the variation of the dimension (the shrink­age) after machine washing according to BSS ISO 6330, by the tensile strength according to BSS ISO 5081, and by the degree of whiteness according to BSS EN ISO 105 J02. The values obtained are compared to those of the same indices but concerning non-treated samples.
Table 1 shows the values of the indices studied, depending on the concentration of the cross-linking agent and the catalyst type in case of a cotton fabric. It is seen from Table 1 that the total angle of relax­ation is increased from 16 to 78 degrees when compared to that of the non-treated sample. It should be noted that crease resistance is only slightly increased when the concentration of DMDHEC is 5 g l^-1and 10 g l^-1. These results can be explained by the insignificant quantity of the cross-linking agent.
The shrinkage is considerably improved when the cross-linking procedure is car­ried out in the presence of DMDHEC at a concentration of 30 g l^-1_, irrespectively of the catalyst used. The shrinkage de­creases even with lower concentrations of DMDHEC (10 g ^l-1 and 20 g l^-1) if catalysts 3 and 4 are used. A higher
 
crease-resistance is reached with the ap­plication of catalyst 3 when compared to that with the rest of the catalysts studied, provided that one and the same concentration of DMDHEC is used. This is due to the higher catalytic activity of the catalyst mixture MgCl2 – citric acid – tartaric acid, most probably determined by a synergistic effect. It is assumed that the latter is connected with the formation of a complex between the metal ion and the organic acid.

It is known that cellulose threads turn yellow on prolonged heating at tempera­tures within the range of 105°C-120°C, because of the accumulation of carbonyl groups at C2 and C3, or as a result of the presence of residues of wax-like sub­stances. The degree of whiteness does not significantly change in most of the cases
studied, which means that the short-term temperature treatment does not affect the threads’ structure. The only exception is observed in the case of catalyst 4 applica­tion, where the solutions are acidic (the pH is ca. 2) and partial hydrolysis of the cross-linked agent is possible. The latter results in side products which affect the samples’ whiteness.
Figure 1a illustrates the effect of the different catalysts used on the tensile strength in the process of cotton fab­ric cross-linking with D
MDHEC of a concentration of 30 g l^-1. All the other samples investigated have a similar be­haviour, although a tendency to tensile strength variation is outlined. It is found that it approaches that of the untreated material upon decrease of the cross-link­ing agent concentration. Figure 1 also
shows the drastic decrease in the ten­sile strength when catalysts 3 and 4 are used. This results from the high catalytic activity and the lower pH values of the working solutions which in fact favour cellulose hydrolysis. This is the reason to recommend lower temperatures when carrying out the cross-linking procedure.
Figure 1b shows the elongation varia­tion with the catalysts studied in a cotton fabric cross-linking in the presence of DMDHEC of a concentration of 30 g l^-1. It is seen that the elongation of the treated material is lower in all the experiments carried out when compared to that of the untreated one, and moreover it cor­responds to decreased tensile strength. These effects are determined by the abrupt decrease in the macromolecules’ mobility resulting from the cross-link­ing. In addition, the formation of each new covalent bond is connected with the disruption of a great number of hydrogen bonds. The energy of the latter is higher than that of the newly-formed one.
The investigations carried out show that the cross-linking with DMDHEC is ef­fective at concentrations not lower than 20 g ^l-1 to 30 g l^-1. This determines the choice of the illustrative data for a vis­cose fabric in this work. Table 2 shows the values of the indices investigated for a viscose fabric in dependence on the cross-linking catalysts used. The data are not comparable to those for cotton fabric. The basic reason lies in the great difference between the structures of both fabrics.
For example, it is known that the amor­phous regions accessible to physico­chemical interactions are only about 20% for cotton, while they are 50-60% for the viscose fabric. Besides, the viscose

52 FIBRES & TEXTILES in Eastern Europe January / March 2005, Vol. 13, No. 1 (49)

threads have a lower average degree of polymerisation (300-400), a lower degree of orientation of the macromol­ecules towards the threads’ axis, and a lower number of hydrogen bonds when compared to those referring to the natural cellulose threads [5]. All these facts in fact determine that the viscose structure is more accessible. But it is also worth mentioning that viscose fabrics are known for their high creasing and shrink­age, which usually reach to 12-16%.
The results in Table 2 also show that the cross-linking degree is high, which affects not only the relaxation angle but the fabric’s shrinkage also. The de­creased shrinkage effect obtained when catalysts 2 and 3 are used is long-lasting, and is most probably determined by the stabilisation of viscose fabric structure resulting from the formation of a great number of covalent bonds. The varia­tion in the tensile strength (Figure 2a) is insignificant. It is likely that the total energy of the bonds formed compensates for that caused by the disruption of the
hydrogen bonds. The degree of whiteness is not changed when compared to that of the untreated viscose fabric.
Figure 2 shows the effect of the cata­lysts studied on the tensile strength and the elongation of a viscose fabric in the case of cross-linking in the presence of DMDHEC of a concentration of 30 g l^-1. A change in the indices followed is observed only in the case of the applica­tion of catalyst 3. This is probably due to the presence of an acid in the work­ing solutions, which catalyses not only the cross-linking reaction but that of the cellulose hydrolysis as well. The macro­molecules’ mobility does not decrease upon the introduction of a small number of chemical cross bonds to the hydrate cellulose threads. The changed values of elongation of cross-linked samples in the presence of catalyst 3 show that the reac­tion results in the formation of a greater number of covalent bonds. The latter limit the macromolecules’ mobility, which in turn leads to decreased tensile strength and elongation.
The effect of HCHO quantity present in the treated fabrics is not covered in the present investigation because (i) the cross-linking agent is of a low HCHO content, and (ii) the concentrations used are lower than those required for creas­ing-resist finish.
Conclusion
The cotton and viscose fabrics cross-linked by a modified DMDHEC (of 20 g ^l-1 and 30 g l^-1) attain a long-lasting effect of decreased shrinkage. The application of the catalyst mixture of MgCl2 – citric acid – tartaric acid intensifies the process of cross-linking, but this is also accompanied by a considerable loss in the cotton fabric strength. The use of the citric acid-tartaric acid catalyst mixture is linked with similar effects.
The structure of the viscose threads prob­ably contains fewer hydrogen bonds, which determines the higher resistance towards the presence of acid when com­pared to cotton threads. This leads to a smaller strength loss when the cross-link­ing is carried out with DMDHEC in the presence of all the catalysts studied.
 

Spinning Mill–Project Profile-Cost-Report

Spinning in conversion of fibers into yarn. These fibers can be natural fibers (cotton) or manmade fibers (polyester). Spinning also entails production of manmade filament yarn (yarn that is not made from fibers). Final product of spinning is yarn. Cotton value chain starts from Ginning that adds value to it by separating cotton from seed and impurities. Spinning is the foundation process and all the subsequent value additions i.e. Weaving_‘ Knitting_‘ Processing_‘ Garments and Made ups_‘ depend upon it. Any variation in quality of spinning product directly affects the entire value chain. 

2. Market:

The world cotton cultivation area and cotton production are estimated at around 30-31 million hectares and 20 million tons respectively. The biggest cultivators of cotton are America_‘ India_‘ China_‘ Egypt_‘ Pakistan_‘ Sudan and Eastern Europe. India is the third largest producers of cotton after USA and China. USA has a considerable share in world exports. India and China both fall short of their domestic requirement and are net importers. Andhra Pradesh is 3^rd largest state in India which grows cotton. Among the consumers China leads the way being followed by India_‘ Pakistan_‘ USA and Turkey.
Indian Textile Industry contributes 4% to the GDP of the country_‘ it contributes 14% to Industrial Production_‘ 9% of excise collections_‘ 18% of employment in industrial sector_‘ and has 16 % share in country’s export. Textile industry provides employment to 35 million people in India.
3. Raw Material:
The main raw material for the spinning process is Ginned cotton will be available in Bales of 170 Kgs/bale.

4. Manufacturing Process& Technology

Spinning process is shown in the flowchart given below. Cotton which is in the form bales is fed to blow room followed by various operations like carding and combing depends on the requirement. The final yarn of required specifications are met through these operations and winded.

5. Technology:
The Plant & Machinery required for the Spinning Mill process for manufacturing yarn of different counts are blow room machinery_‘ metal detection system_‘ spark diversion system_‘ carding machines_‘ card accessories_‘ draw frame (Finisher & Breaker)_‘ speed frame_‘ combers_‘ ring frame_‘ electrical infrastructure_‘ yarn testing
instruments_‘ humidification and waste collection system and automatic cone winding machine etc.
6. Investment:
The investment for setting up a spinning mill with a capacity of 14400 spindles works out to Rs. 26.90 Crores and the break up of the cost is tabulated below.
The land requirement will be around 2.5 acres. The Preliminary & Pre-operative expense works out to Rs 1.36 crores. Plant & Machinery including installation_‘ erecting & transportation charges are of 16.91 Crores. Buildings and civil works are estimated to be 6.55 Crores. Errection & Transportation and electricity deposits have been considered in the project cost. Margin money for working capital is estimated to be 1.60 Crores.

Means of Finance
The project is proposed to finance with a debt equity ratio of 2.26:1 and the
means of finance is as follows:

7. Profitability Assumptions:

Basic assumptions of the spinning mill are given in the table below:
The total production per day of some of the products considered is given in the
table below:

The spinning mill can work at 85 % for the first year_‘ 90 % in the second year and
95% is considered from third year onwards. The manpower requirement is
considered at 185 personnel for various level viz. Spinning master_‘ Accountants_‘
casual labors_‘ Technical & Supervisory staff and administrative staff.
8. Key Financial indicators:
The returns are adequate enough to repay the term loan in 10 years. The key financial indicators are tabulated below.

Micro Dust Remover–Working Principle

Material from the preceding machine is thrown with a great force by the transport fan on the screen. The oscillating dampers help in distributing the material evenly across the width of the screen. This results into smaller tufts coming in contact with the perforated screen. The liberated micro dust is removed by the dust transport fan which is placed on the opposite side of the screen. After the material slides down, it is sucked away by either a condenser or a material transport fan.
It is recommended to use the micro dust remover after the last beating point where the cotton is in open form so that the micro dust can be removed easily.


Constraints for removing micro dust by Condensers
· Limited surface area contact of material with cage
· Overlapping of raw material at cage – results into inefficient micro dust removal; micro dust gets embedded inside the tufts which are difficult to remove later on.
Micro dust hampers the smooth working of Ring and Rotor spinning as follows
· Quality of yarn is affected due to thick, thin places and Neps
· Production loss due to higher end breaks
· Reduced Life of the rotor

Majority of cotton varieties are contaminated with leafy particles, seed coats, micro dust etc. Some part of the micro dust is removed in blow room through condensers and other opening points. But most of the micro dust is carried further which no regular machine in the process can remove.

Lap to Chute Feed Conversion

The material from the blow room cleaning lines is directed to the chutes which are erected behind individual cards. The material feed is regulated through a pressure transducer and a VFD drive which is fitted at the last feeding point to ensure constant and uninterrupted feed to cards.
The chute consists of top chamber, feed roller, beater, bottom chamber, delivery rollers and in built fan.
The material from the chute is dropped in the top chamber through a material transport fan. The air carrying the material escapes through the perforated sheet provided in the top chamber. As the card starts, the material from the top chamber is fed into the bottom chamber through the feed roller and beater. Due to beater action, the material in the bottom chamber is in an open form.
The in built fan air is directed in such a way that it compresses the material in the bottom chamber. The pressure transducer regulates the feed in the bottom chamber so that the material level remains constant during the card working. The sliver of the card is again controlled through auto leveler provided in the cards.


• Direct Feeding to cards leads to saving of man hours
· Cleaning efficiency of cards is improved due to open fibre
· The complicated scutcher machine is replaced by the simpler chute feed
· Less space is required
· Less power is required

Dust Compactor For Spinning Mill

Most of the filter manufacturers provide dust bags to collect dust generated on the secondary side of the filter plant. The air accompanying the dust escapes through the bags leaving the dust on the bottom of the filtered bags and this dust is required to be removed manually from time to time. The bags also have to be removed once a week for thorough cleaning. This sometimes leads to tearing of bags which then need to be replaced. During the dust removal, a lot of dust is spread over in the room, making the room very untidy and posing a health hazard for the workers cleaning the filter installation. Clogging of bags leads to a back draft and the suction pressure at the nozzles drops down which clogs the secondary filter media.


To overcome this problem, we have developed a dust compactor which is fitted at the end of the cyclone. The air from the cyclone is diverted back into the secondary filter and the dust collected from the bottom of the cyclone is passed through the dust compactor which compacts the dust in ball forms which are collected in a drum placed under the dust compactor.
The dust compactor works on a continuous basis without need to stop the plant. No bags are used thus eliminating the cleaning and changing of bags in earlier system. This increases the productivity of the plant for which the filter system is provided.

Filters and Waste Removal Systems–Blow room

Due to technological advances, all the Filters and Waste Removal Systems manufactured now are with positive exhaust. In the earlier filers supplied by all the leading manufacturers of Blow Rooms, the air was allowed to escape from the secondary filter at atmospheric pressure. This was causing back pressure requiring frequent cleaning of filter media of the secondary filter resulting in loss of production.
We are glad to inform you that we have now developed Conversion kits for these old types of filters to change them into positive exhaust systems. Due to this conversion the air escaping from the secondary filter is removed by a Centrifugal Fan thus creating a vacuum allowing exhaust from the Blow Room machines to get a free passage.

The conversion consists of the following items
· Centrifugal Fan with 11 k.w Motor
· Fabricated parts to connect existing filter to an extended chamber for Centrifugal Fan
· 5 H.P Blower for Suction Nozzle to remove dust from the Secondary Filter media
· Dust Compactor
Benefits of the Conversion
· Better suction at Blow Room
thus avoiding beater jamming
· Better cleaning efficiency due to pressure drop on the exhaust side of the Condensors
· Less stoppage of Filter Systems
thus increasing productivity
· Cleaner atmosphere in the Filter Room as otherwise due to increased pressure the dusty air comes out through the door which is some times kept open to avoid back pressure

The 5 H.P Blower will be used for suction through Nozzle for better cleaning of the secondary filter media. The Dust Compactor will be used to replace the existing filter bags which require frequent cleaning and create air pollution as dust escapes from the bags while cleaning the same. The Dust Compactor does not require any cleaning and the dust is collected as a ball form in a drum kept under the Compactor.

Contifeed System for Chute Feeding – Working Principle

We have indigenously developed a Contifeed System for Chute Feeding. The system can be incorporated for all makes of Blow Rooms with chute feed. At present this system is offered by OEM in the latest supplied blow room lines.
Working Principle
The Pressure Transducer will sense the air pressure of the main duct line supplying material from Blow Room to Chutes. Depending on the quantity of the material required by the Chutes, the speed of supply motor situated at the last beating point in Blow Room will increase or decrease its speed.
If all the Chutes are empty, the Motor will work at its maximum speed. As the Chutes get filled, the motor speed reduces, thus the supply of material equals the demand. This helps in maintaining a constant material height in Chutes and ensures even feed from top reserve box of the Chutes to the Cards. The Motor will stop only if all the Cards are stopped and no feed is required.
The conventional blow room lines have the motor working on start/ stop principle. So the quantity of the material delivered from the blow room is constant irrespective of the requirement from the cards. The varying material level in top reserve box of chutes affects the supply to cards.
In Contifeed system, the material requirement is matched with proportionate supply by varying the delivery motor speed of last beating point.
The Contifeed System consists of
· Pressure Transducer Assembly
· Variable Frequency Drive (V.D.F) with line choke for the last beating point motor
· Control Panel
Merits of the system
· Reduced CV% of Cards sliver by consistent supply of raw material
· With conventional system in a situation where only few cards are working the inflow of material is high with respect to the quantity required by the cards. The higher feed yields to jamming of the cards. The use of Contifeed System helps avoid such blockages.

 

The difference between Axi-Flow and Maxi-flow

For Axi-flow machine, higher suction is necessary at material entry point for transportation of cotton from preceding machine to the next machine through Axi-flow.
Due to higher suction, cotton passes through the beater very quickly thus resulting in bigger tuft size and less cleaning. It also results in loss of good fiber under the beater.
In Maxi-flow, the material is dropped in the machine by gravity through a condenser and advances with the beater action. The material is removed from Maxi-flow with the help of suction from the next machine.


The conversion consists of
· Condenser
· Material Feeding duct with photocell
· Side door with top opening
· Out let duct and air adjusting system
· Beater motor of 7.5 KW
Benefits of conversion
· Increase in machine cleaning efficiency by 40 – 50%, thus resulting in better yarn quality
· Reduction in lint loss
· Higher cleaning without any damage to fibers through efficient usage of air currents
· Less neps due to better opening at this point

The cleaning efficiency of Axi-flow machine is a very important parameter for quality yarn spinners. We offer a conversion for improvement in Axi­flow machine. The modified machine “Maxi-flow” is the best solution to improve the cleaning efficiency of Axi-flow machine.
Conversion time is maximum one day and it can be carried out without losing production by bypassing the machine for a short period.
Also, conversion can be done without shifting the machine from its installed position.

GINNING MILLS – PROJECT PROFILE

Ginning is the first mechanical process involved in processing cotton. Ginning mill separates cotton fibers from the seed bolls and dust particles. The main application of ginned cotton referred to as lint is for spinning operations, where lint is converted to yarn.

2. Market:

World production of cotton stood at 137.8 million bales in the year 2008-09. The leading producers include China, India, USA, Pakistan, Brazil, and Turkey. Cotton textile commands a significant share in exports from India. It accounts for nearly 22% of the total exports. Area, production and productivity of cotton in India in the year 2008-09 stood at 93.73 lakh hectares, 290 lakh bales(170 Kg of each bale) , 526 Kgs per hectare.
A.P. stands 3^rd rank in Cotton area in India with 10.96 lakh hectares (Ha) next only Maharashtra (31.91 L.ha) and Gujarat (25.96 L.ha). The share in area of A.P. in India is 11.5 %. It also stands 3rd in cotton production in India with 43.00 Lakh bales (Bale is 170 kg each) with an average yield of 667 Kgs next only to Maharashtra (60.00 L.B) and Gujarat (110.00 L.B). Adilabad, Guntur and Warangal had recorded higher growth in cotton area cultivation and production.
3. Raw Material:
The raw material considered for the ginning operations is Raw Cotton/ Kappa cotton available in candy of 356 Kgs/candy. The classification of cotton fiber as adopted by the CAB is given in the table below:
Classification of Cotton Fiber

4. Manufacturing Process& Technology

Ginning process is shown in the flow chart given below. Seed cotton is fed to grading system where grading is done followed by pneumatic conveying. From here it is fed to preliminary cleaning process, followed by saw gin, lint cleaner, pre-bale press and cotton bales.
Ginning Process involves two cleaning stages:
1. Pre Cleaning
2. Post Cleaning

The main operation of separating seed from cotton is done by saw gin. In the gin house after ginning process is completed the cotton lint and cotton seeds are separated and the lint passes out through pneumatic system to the Post-cleaner (Lint Cleaners) in which small impurities, dust particles, small fibers are carried out and cotton becomes free from contamination.

Pressing:

Cleaned Lint is taken to the bale press which compresses the ginned lint into bales that weigh around 170 Kgs. After pressing is completed the bale is tightened and covered fully with cloth, after then the bale is weighed and kept in the hall safely.
Packaging the Lint:
The bales are then wrapped with a protective cover, ready for delivery to the warehouse where they are sold to various textile mills

5. Technology:

The technology required for the ginning & pressing operations are cotton ginning machinery, pre cleaner, lint cleaner, Kappas conveyor system, lint conveyor system, Hydraulic cotton baling press, conveyor for seed, electrical infrastructure, Humidifier and weigh bridge etc. The other optional machinery required is the foreign fibre detectors/ removers.
Minimum economic size of the plant:
The minimum economic capacity of the ginning mill is about 24 Gins.
Yield and Production:
The yield of lint cotton is assumed at 32%, seed is assumed at 65% and waste is assumed at 3% which are based on the industrial norms and manufacturers specifications.
6. Investment:
The investment cost for setting up a ginning mill of 24 gins will be around Rs. 9.64 Crores and the break up of the cost is tabulated below.
The land requirement will be around 7 acres. The pre~operative expense includes interest during construction of Rs 0.24 crores. Plant & Machinery including installation, erecting & commissioning charges are of 2.63 crore. Buildings and civil works are estimated to be 2.73 crore. Contingencies, electricity deposits are also considered in the project cost. Margin money for working capital is estimated to be 3.54 crore.

Means of Finance
The project is proposed to finance with a debt equity ratio of 0.79:1 and the means of finance is as follows:

7. Profitability Assumptions:
Basic assumptions of the ginning mill are given in the table below:

The Ginning unit can work at 75% of installed capacity with operating days of 180 days per annum because of the seasonal availability of the cotton. The manpower requirement is considered at 100 personnel for various level viz. casual labour, Technical & Supervisory staff and administrative staff.
8. Key Financial indicators:
The returns are adequate enough to repay the term loan in 9 years. The key financial indicators are tabulated below.