LAB EXPERIMENT 01 DESIZING DESIZING Removal of the size (desizing) by exhaust method PERFORMANCE/OBJECTIVES Upon the successful completion of this experiment students will be able to (i) Understand the process of desizing (ii) Understand the exhaust method of desizing Tools: Greigh Fabric HT Dyeing Machine CHEMICALS REQUIRED Desizer Wetting Agent Electrolyte Theory: Sizes are applied on the wrap yarn before it reaches the weaving machine. Purpose of any sizing process is to increase weaving productivity by reducing wrap breakage. Wrap yarns are more prone to breakage due to extensive forces acting on them during weaving. For example, tension of the drop wires of (wrap stop motion), shade opening by heald frames, friction of the weft insertion median and beat up forces of the reed etc. Sizes are not applied on the weft yarn because it is less likely to be processed under extensive forces and tensions. Sizes are not applied on the yarn to be used in knitting because of the less likelihood of the forces on the yarn. At the same time fabric is formed in this process by interloping through knitting Mujahid Mehdi Page 1 Name: _____________________________________________ ID No. ____________________ Signature of the lab tutor________________________
Transcript
LAB EXPERIMENT 01 DESIZING DESIZING
Removal of the size (desizing) by exhaust method
PERFORMANCE/OBJECTIVES
Upon the successful completion of this experiment students will be able to
(i) Understand the process of desizing(ii) Understand the exhaust method of desizing
Tools:
Greigh Fabric HT Dyeing Machine
CHEMICALS REQUIRED
Desizer Wetting Agent Electrolyte
Theory:
Sizes are applied on the wrap yarn before it reaches the weaving machine. Purpose of any sizing process is to increase weaving productivity by reducing wrap breakage. Wrap yarns are more prone to breakage due to extensive forces acting on them during weaving. For example, tension of the drop wires of (wrap stop motion), shade opening by heald frames, friction of the weft insertion median and beat up forces of the reed etc. Sizes are not applied on the weft yarn because it is less likely to be processed under extensive forces and tensions.
Sizes are not applied on the yarn to be used in knitting because of the less likelihood of the forces on the yarn. At the same time fabric is formed in this process by interloping through knitting needles and these needles do not exert such huge tension that may require application of size.
Overall, the sizes serve to achieve the following purposes:
a. To increase the strength of yarnb. Reduction in yarn hairinessc. Increase resistance against abrasiond. Reduce the chance of fluff and fly during weaving.
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Name: _____________________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date:_____________________
Usually sizes are applied on the yarn from aqueous solution and they form a film of polymers on the yarn. These film forming substances or sizes can be classified into two major groups as given in the chart below.
100% cotton fabrics are mostly sized with starch based sizes and cotton/polyester blends with PVA to achieve higher weaving efficiency at optimum cost. Most made fibers on the other hand can be sized with poly vinyl alcohol and poly-acrylic acid sizes.
After weaving, the sizes must be removed from the fabric before it is to be dyed or finished. This is accomplished during the preparation of the fabric for coloring or finishing (pretreatment). The process in which these sizes are removed is called desizing. Extent is decided on the following criteria.
a. Sizes% applied on the yarnb. Construction of the clothc. Nature of the size and its viscosity of the size solutiond. Desizing methode. Chemical auxiliaries used in the bath
Water soluble sizes like CMC, PVA and acrylates mostly do not need chemical desizing; they can be readily desized with hot water. Addition of wetting agents may be helpful. Starch on the other hand requires especial attention. It is a carbohydrate polymer composed of 25% amylose and 75% amylopectins. Amylose is the inner and relatively soluble portion of starch and it is polymer of glucose that consist of long chains of glucose units joined together by 1,4-glycoside linkage. Amylopectin is the outer and almost insoluble portion of a starch and it is highly branched glucose polymer. Hence, removal of the starch needs some sort of chemical treatment to break down it into water soluble glucose and dextrin.
For the removal of starch, variety of desizng agents can be used. For example:
a. Bacteriab. Acids c. Oxidizing agents d. Enzymes
Bacterial:Bacterial desizing is sometimes called rot steeping. Cotton is wetted in the water and is left in the damp conditions for several hours. Numerous bacteria present in the environment will degrade the starch in damp and warm conditions. This process of desizing is time consuming and at same time there are chances of degradation of cellulose of cotton and its blends by bacteria.
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Acids:Sulphuric acid and hydrochloric acid (dilute solution and under cold conditions) can be used to degrade the starch. Normally, fabric if soaked in the dilute solution of the acid and then it is left for two to three hours at room temperature. As the acids are prone to dissolve the cellulose, hence this process requires crucial control of temperature and tie; it may cause serious damage to the cotton.However, the main advantage of acid desizing is that it requires less time for degradation of starch and any metal particles present in the fabric are readily removed in the process.
Oxidizing Agents:Oxidizing agents like Hydrogen per Oxide (H2O2) and per-sulphates may be used to degrade the starch without degrading cellulose. As H2O2 is used in the process of bleaching, it is economical to carry out both desizing and bleaching in one process. However, it can be a suitable choice, if only, amount of size on the fabric is too less.
Enzymatic desizing:Enzymatic desizing is the more suitable and most widely used method of desizing the starch. Enzymes are the bio-catalysts having specific action on the surface; a family of the enzymes known as amylases converts the insoluble starch into numerous soluble scahardies by increasing the rate of hydrolysis.The enzymes breakdown the starch into water soluble sugar, maltose and dextrin; these water soluble products can easily be washed out.
T ypical Recipe
Chemical Quantity Parameter Range
Liquor Ratio
Siruxx2ud
NaCl
Bactosol MTN
Procedure:
1. Weigh the fabric and prepare the chemical bath according to the recipe.2. Check pH of the bath and if required maintain it with acetic acid.3. Dip the fabric in the chemical bath and load on the water bath.4. Adjust all process parameters on the machine and start operation.5. When process is completed hot rinse at 80-90°C for 10-15min and then cold rinse for
3mins.6. Finally dry Desized fabric at 90°C in an oven.
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Calculations:
S.NO Material Quantity
1 Fabric weight
2 Total liquor
3 Bactosol MTN
4 Siruxx 2UD
5 NaCl
%of starch removed = (initial weight of sample –final weight of sample)x100% Initial weight of sample% of starch removed = x 100% = %
Test Results:_________________________________________________________________________
1. Clean your machinery equipment/material and workbench before you leave.
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2. Ensure the replacement of all equipment to their specified storage area.3. Submit your answer to questions together with your data, calculation and results
before the next laboratory/experiment
LAB EXPERIMENT 02 DESIZING
Removal of the size (desizing) by pad-batch method
PERFORMANCE OBJECTIVES
Upon the successful completion of this experiment students will be able to:
(i) Understand the process of desizing(ii) Understand the pad-batch method of desizing
MACHINES/MATERIAL REQUIRED
Greigh fabricHorizontal or vertical paddersAcetic acid
DISCUSSION
In the desizing process, size applied on the fabric prior to weaving is removed. The process of desizing can be accomplished either by “hydrolysis” or by “oxidation”. Water soluble size like PVA and CMC are readily Desized by hot water; wetting agent are added if required. However, starch is water insoluble and cannot be readily degraded by simple hot washed. For removal of starch numerous degrading agent or desizing agents are used for the removal of starch are:
1.Enzymes2.Dilute solution of acids3.Bacteria &4.Oxidizing agents
Detail descript ion of the desizing process and desizing agents is given in the previous practical.
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Name: _____________________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date:_____________________
Typical Recipe
Chemical Quantity parameter range
TOTAL LIQUOR
Sandoclean Pc
BactosolHC1000
SIRRIX2UD
PROCEDURE
1. Prepare chemical/ desizing bath according to recipe and maintain its ph with acetic acid
2. Adjust the pickup % age of the padders &pad the fabric 3-5 times at room temp:
3. Make the roll of padded fabric,4. Put it in polyethylene bags and keep for 12-24 hrs (batching time)5. Hot rinse at 90-100 c for 1.5-2 minutes 6. Hot wash twice at 90-95c 7. Warm wash at 60c and8. Finally cold wash for 10 min:9. Dry the fabric at 70c in an oven or dryer.
Calculations
S no
1 Total liquor
2 Sandoclean pc
3 BactosolHC1000
4 Sirrix 2UD
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% of starch removed = (initial weight of sample – final weight of sample) x100%
1.Clean your machinery equipment/ material and workbench before you leave.2.Ensure the replacement of all equipment’s to their specified storage area.3.Submit your answer to questions together with your data, calculation and results
before the next laboratory/ equipment.
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LAB EXPERIMENT 03
To determine starch contents in the Greigh fabric
PERFORMANCE OBJECTIVE
Upon the successful completion of this experiment student will be able to:
i. Understand purpose of different sizes applied on yarns ii. Understand the way to evaluate size contents in the fabriciii. Understand the calculating size content
DISCUSSION Sizes are chemicals applied on the warp yarns prior to weaving so that the yarn can with stand wear and tear and different tensions during weaving process .There are there types of sizes that are conventionally applied on the warp yarns
i. Natural Sizes (eg. Starch)ii. Synthetic sizes (eg.PVC)iii. Natural polymer based sizes (eg.CMC)
The amount of size used is mentioned by the greigh department so as to decide the extent of desizing to be carried out
PROCEDUREPrepration of KI solution
Dissolve 10 grams of KI ( potassium iodide ) in 100 ml demineralized water until it is completely dissolve
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Name: _____________________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date:_____________________
Make the volume up to 800 ml with water Finally add ethanol to make the volume up to 1000 ml
Precautions for Ki Solution
Don’t expose the sun light Store in the brown bottle and used within 3 months
ASSESMENT OF SIZE CONTENTS
Pour few drops the Ki solution of the fabric to be tasted Rub the cloth gently Compare color change with violet scale and no rating
NOTE:1. Fabric must be brought to room temperature before conducting the test
2. Before conduction of test the fabric PH should be neutralized
Evaluation
Color change Quantity of starch
No change No of starch is present
Pale blue Trace of starch
Bluish brown Appreciable amount of starch
Brown Modified starch PVA
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Test results:
Violet Scale rating _____________________________
%age of size content in the fabric _________________
1. Clean your machinery equipment’s /materials and workbench before you leave 2. Ensure the replacement of all equipment’s to their specified storage area 3. Submit your answer to question together with your data. Calculation and result before
the next laboratory /experiment
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LAB EXPERIMENT 04
To determine absorbency of fabricPERFORMANCE OBJECTIVES
Upon the successful completion of this experiment, the students will be able to:
1. Understand effect of absorbency of fabric on coloration and finishing process2. Determine absorbency of the specimen
CHEMICALS REQUIRED
Direct Dye (Turquoise Blue) De-ionized water
DISCUSSION
Absorbency of the fabric determines how easily it allows water molecules to be absorbed. Absorbency tests are mostly carried out on cellulose and cellulose blend to determine the extent a particular fabric could absorb dye, water or any other chemical. It can be determined by several methods e.g. AATTCC test method 79 and DIN 53924; these include determination of time taken for standard drop to be absorbed.
Absorbency can be increased with the application of chemicals called wetting agents. These are mostly surface active gents which, when applied on substrate, reduce surface tension of water (force that pulls the surface molecules inwards), as a result of decrease of surface tension, absorbency of fabric is increased. process etc.
PROCEDURE
1. Cut a piece of fabric into 10X 4 cm specimen, mark line on it 1 cm apart from each other and number like scale.
2. Take a Petri dish or beaker and fill it with 1% solution of turquoise blue direct dye.3. Suspend strip of fabric over the solution so that exactly about 1 cm of the lower end
of sample is immersed in solution.4. Keep the sample immersed for 60 seconds.5. Take the sample out and without wasting any time iron so that the dye may not
further spread.6. Finally, assess the absorbency of fabric by the height at which dye solution reached
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Student Name: ___________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date: _____________________
TEST REULTS
Sample. No Absorbency
1
2
3
4
5
REVIEW QUESTIONS
1. Define absorbency?
2. What should be absorbency of fabric that is to be printed or dyed with pigment dye?
3. Discuss importance of absorbency of fabric in dyeing?
FINAL CHECK LIST
1. Clean your machinery equipment/materials and workbench before you leave.
2. Ensure the replacement of all equipment’s to their specified storage area.
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3. Submit your answers to questions together with your data, calculation and result before the next laboratory/ equipment.
LAB EXPERIMENT 05
Removal of natural and added impurities (scouring) by exhaust method
PERFORMANCE ABJECTIVE
Upon the successful completion of this experiment student will be able to(i) Understand the mechanism of scouring and cotton of auxiliaries used(ii) Understand the exhaust method of scouring
MACHINES/MATERIAL REQUIRED
Desized fabric HT dyeing or Oscillating Dyeing machines
CHEMICAL REQUIRED
Caustic soda Wetting agent Sequesting agent
DISCUSSION
Natural cellulosic fiber like cotton and flax contain natural impurities like pectin’s, lignin, waxes and fats along with some added impurities such as oil stains, dirt and dust particle etc. Amount of these impurities present in different varieties of cotton and flax are given in the table below
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Student Name: ___________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date: _____________________
Scouring is the process in which impurities present in the cellulosic fibers are removed by treating it with alkali. In the process fats, waxes, proteins, oils, pectin’s, ash miscellaneous substance such as pigments amid cellulose and reducing sugure etc are removed from the fabric. The typical process consists of boiling the fabric with 3 to 6 % solution of sodium hydroxide (NaOH). Fats and waxes are insoluble in water, when alkali (NaOH) reats with them, soap is formed .This process is called saponification.
TRIGLYCERIDES:
This soap is not only water soluble but also has detergent properties. This will need to removal of the dirt impurities.During scouring of the natural cellulosic fiber, 5 to 10n % of the weight are lost as a result of removal of impurities. This weight loose is because of the degradation and the solution of the impurities like fats, waxes, proteins, pectin’s and lignin etc. however wettability and absorbency of the substrate is increased.
TYPICALL RECIPE
CHEMICAL QUANTITY
Liquir ratio 1:2
Caustic soda 1.0 – 2.0 %
SANDOPAN dtc (PASTE) 0.25- 0.5 G/L
Sirrix AK (liquid) 0.5 – 2.0 g/l
PROCEDURE
1. Prepare the bath according to the recipe 2. Start the process at 40 C 3. Treat the fabric at 100 C for 30 – 60 min 4. Finely hot rinse the fabric at 80 – 90 for 10 – 15 min 5. Cold rinse
Solomatic bleaching serves to remove almost all of the impurities including fats, waxes, proteins, pectin, ash, chlorophylls and xanthophyll’s and also seed fragments. Thus it is an economical process saving both the time and the money. However, if full if full white fabric with high degree of whiteness is intended then, it is better to perform both the process separately to achieved best results.
1. Describe soap formation while scouring of cotton fabric?
2. Explain the roll of emulsifier in scouring?
3. How a NaOH solubilizes fats and waxes?
FINAL CHECK LIST
1. Clean your machinery equipment/materials and workbench before you leave.
2. Ensure the replacement of all equipment’s to their specified storage area.
3. Submit your answers to questions together with your data, calculation and result before the next laboratory/ equipment.
LAB EXPERIMENT 06
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Name: _____________________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date:_____________________
Bleaching of 100 % cotton fabric by exhaust methodPERFORMANCE ABJECTIVE
Upon the successful completion of this experiment student will be able to(iii) Understand the bleaching process for 100% cotton fabric(iv) Understand the role of auxiliaries in the process
MACHINES/MATERIAL REQUIRED
Scoured fabricHT dyeing or oscillating Dyeing machine
CHEMICAL REQUIRED
Hydrogen per oxideCaustic sodaStabilizerWetting agent Sequesting agent
DISCUSSION
During the scouring of cotton impurities like fate, waves. Proteins and ash is removed However>scouring does not remove natural color of cotton. It also does not completely removed seed and husk. To remove natural color of the cotton and seed fragment bleaching process follows the scouring. Sometimes both scouring bleaching are simultaneous carried out, the process is called solomatic bleaching.
Cotton contains natural pigments called (CHLOR0PHYLLS) and (NANTHOPHYLLS), which cause its color to be yellowish. In the process of bleaching these pigments are removed from the cotton fiber. Along which these pigments seed fragment are also removed. Thus bleaching accomplishes purification of the fiber.
1.Hydrogen per oxide
Hydrogen per oxide is comparatively expensive bleaching agent .But, because of case of application, least threat from the substrate and environment friendly nature, and it is widely used for the removal of natural pigments.2.Sodium hypo-chlorite
If ph is not controlled during NaOCl bleaching, it will degraded cellulose, because of the formation of the hypo-chlorous acid at natural pH (7) and liberation of chlorine gas at pH lower than 7 ,however ,under controlled condition ,it may be a suitable option .
3.Sodium chlorite
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Sodium chlorite when used as a bleaching agent produces chlorine dioxide (even a controlled process), which is extremely toxic .At the same time, it is extremely corrosive to the machinery because of this it is least preferred bleaching agent,
Chemical Quantities
Liquor Ratio 1:2
Hydrogen per Oxide (35%) 3.0 ml/l
Caustic soda (solid) 3.0 m/l
Sandoclean PC-LF (paste) 1.20-2.00 g/l
Stabilizer SAIF (liquid) 0.5 g/l
Sirrix 2UD 1.0-1.5 g/l
PROCEDURE
1. Prepare the bath according to recipe 2. Pad the fabric at 40 C pick up⁰3. Treat the fabric at 90 C for 20-30 min4. Cool down to 70 C and drain 5 Cold rinses at 40 C for 10 min: 6 finally rinse the fabric hot (at 80 C for 10 minutes)
Calculations
S.No Material Quantity
1 Fabric Weight2 Total liquor 3 Hydrogen per Oxide 4 Caustic Soda 5 Stabilizer SIFA6 Sirrix 2UD7 Sandoclean PC-LF(paste)
1. Clean your machinery equipment’s /materials and workbench before you leave 2. Ensure the replacement of all equipment’s to their specified storage area 3. Submit your answer to question together with your data. Calculation and result before
the next laboratory /experiment
LAB EXPERIMENT 07 BLEACHING
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Student Name: ___________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date: _____________________
Bleaching of 100%cotton fabric by continuous methodPERFORMANCE/OBJECTIVES
Upon the successful completion of this experiment students will be able to:
I.Understand the bleaching processII.Understand role of auxiliaries used in this processIII. Understand the continuous bleaching process
MACHINES/MATERIAL REQUIRED
Scoured fabricPad-steam machine
CHEMICAL REQUIRED
Hydrogen per OxideCaustic SodaStabilizerWetting AgentSequestering Agent
THEORY:
During the scouring of cotton impurities like fats, wax, proteins, pectin’s and ash is removed. However, scouring does not remove natural color of cotton. It also does not completely remove seed and husk. To remove natural color of the cotton and seed fragment bleaching process follows the scouring. Sometimes both scouring and bleaching are simultaneously carried out; the process is called Solomatic bleaching.
Cotton contains natural pigments called chlorophylls and xanthophyll’s, which cause its color to be yellowish. In the process of bleaching these pigments are removed from the cotton fiber. Along with these pigments seed fragments are also removed. Thus bleaching accomplishes purification of the fiber.
1.Hydrogen per Oxide (H202):
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Hydrogen per Oxide is comparatively expensive bleaching agent. But , because of ease of application, least threat for the substrate and environment friendly nature, it is widely used for the removal of natural pigments.
2.Sodium hypo-chlorite (NaOCl):If the pH is not controlled during NaOCl bleaching, it will degrade cellulose; because of the formation of the hypo-chlorous acid at neutral pH (7) and liberation of chlorine gas at pH lower than 7. However, under controlled condition, it may be suitable option.
3.Sodium chlorite (NaClO2):Sodium chlorite when used as bleaching agent produces chlorine dioxide (event at controlled process), which is extremely toxic. At the same time, it is extremely corrosive to the machinery because of this it is least preferred bleaching agent.
Depending on the extent of bleaching, fabric may be said to be half bleached or full bleached. In the half bleached fabric, some of the natural pigments are removed and fabric yet contains chlorophyll and xanthophyll’s. However in case of full bleached fabric, almost all natural pigments are removed. The removal of the natural color of the cotton, its whiteness is increased. A normal bleached fabric may achieve whiteness index of about 60 to 75 or sometimes 80.
Typical Recipe
Chemical Quantity
Liquor Ratio
Hydrogen per Oxide (35%)
Caustic soda (solid)
Sandoclean PC-LF (paste)
Stabilizer SIFA (liquid)
MgCl2
PROCEDURE
1. Prepare the bath according to recipe.2. Pad the fabric at 80% pick up.3. Steam (saturated) the fabric for 20-30 min: at 102°C.4. Hot rinse at 80°C-90°C for 10 min:5. Warm rinse at 60°C for 10 min: and finally cold rinse for 5 minutes.
Calculations
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S.NO Material Quantity
1 Fabric Weight
2 Total Liquor
3 Hydrogen per Oxide
4 Caustic Soda
5 Stabilizer
6 MgCl2
7 Sandoclean PC-LF (paste)
TEST REULTS
REVIEW QUESTIONS
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1.What is role of MgCl2 in H2O2 bleaching?
2.What are the advantages of continuous bleaching over exhaust bleaching process?
3. What are reasons of foaming and how it can be avoided?
FINAL CHECK LEST
1.Clean your machinery equipment/ material and workbench before you leave.2.Ensure the replacement of all equipment’s to their specified storage area.3.Submit your answer to questions together with your data, calculation and results
before the next laboratory/ equipment.
LAB EXPERIMENT 07
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Student Name: ________________________________ ID No. ____________________
Signature of the lab tutor: ___________________ Date: _____________________
Solomatic bleaching of pc blend fabric by exhaust method
PERFORMANCE OBJECTIVE
1. Desized Fabric2. HT dyeing or Oscillating Dyeing Machine
CHEMICAL REQUIRED
Caustic Soda Hydrogen per oxide Stabilizer Wetting agent Sequsting agent
DISCUSSION
In solomatic bleaching, both the scouring and bleaching processes are carried out simultaneously for economical processing Scouring is the process impurities present in the cellulosic fabric are removed by treating it with alkali. In this process fats, waxes, proteins, oils, pectin, ash, miscellaneous substance such that is pigments, hemicelluloses and reducing sugars etc are removed from the fabric .The typical process consist of boiling the contaminated cotton fabric with 3 – 6 % solution of sodium hydro oxide (NaOH). Fats and waxes are insoluble in water, when alkali, (NaOH) reacts with them, soap is formed .This process is called saponification.
Soap formed during saponification is not only water soluble but also has detergent properties. This property will lead to removal of the dirt and other insoluble impurities.
Cotton contain natural pigments called CHLOROPHYLL and XANTHOPHYLLS, which caused it color to be yellowish. In the process of bleaching these pigments are removed from the cotton fabric .Along with these pigments seed fragments are also removed. Thus bleaching accomplishes purification of the fiber.
Solomatic bleaching serves to remove almost all of the impurities including fats, waxes, proteins, pectin, ash, chlorophylls and xanthophyll’s and also seed fragments. Thus it is an economical process saving both the time and the money. However, if full if full white fabric with high degree of whiteness is intended then, it is better to perform both the process separately to achieved best results.
Typical Recipe
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Chemical Quantities
Liquor
Caustic Soda
Hydrogen per oxide
Stabilizer Y2K
Sandoclean PC-LF (paste)
Sirrix 2UD
PROCEDURE
1. Start process at 60 C with Sandoclean PC-LF 0.5 – 1.0 % Sirrix 2UD 1.0 %
2. Immerse fabric and treat at 60 C for 15 min .then add Caustic soda (solid) 1.0 % Stabilizer Y2K 0.25 – 0.5 % Hydrogen per oxide 2.0 – 3.0 %
3. Rise the temperature o bil and treat at boil for 20 – 30 min 4. Cool down to 70 C for 15 min5. Hot rinse at 80 C for 15 min6. Cold rinse at 40 C for 10 min
1. Clean your machinery equipment’s/material and workbench before you leave
2. Ensure the replacement of all equipment’s to their specified storage area Submit your answer to question together with your data, calculation and result before the next laboratory/experiment.
LAB EXPERIMENT 09
Solomatic bleaching of pc blend fabric by continuous method
PERFORMANCE ABJECTIVE
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Name: _____________________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date:_____________________
Upon the successful completion of this experiment student will be able to:
(v) Understand the solomatic bleaching process and roll of auxiliaries used (vi) Understand and perform solomatic bleaching by continuous method
MACHINES/MATERIAL REQUIRED
Desized fabric
Pad steam machine
CHEMICAL REQUIRED
Hydrogen per oxide
Caustic soda
Stabilizer
Wetting agent
Sequesting agent
DISCUSSION
In solomatic bleaching both the scouring and bleaching process are carried out simultaneously for economical processing.
Scouring is the process impurities present in the cellulosic fibers are removed by treating it with alkali. In this process fats, waxes, proteins, oils, ash substances such as pigments hemi cellulosic and reducing sugar etc are removed from the fabric. The typical process consists of boiling the contaminated cotton fabric with 3- 6 % solution of sodium hydroxide. Fats and waxes are insoluble in water when alkali reacts with them, Soap is formed .this process is called saponification
Soap formed during saponification is not only water soluble but also has detergent properties this property will lead to the removal of the dirt and other insoluble impurities
Cotton contains natural pigments called chlorophyll’s and xanthophyll’s , which cause its color to be yellowish in the process of bleaching these pigments are removed from the cotton fiber .Along with these pigments seed fragments are also removed. Thus bleaching accomplishes purification of the fiber.
Solomatic bleaching serves to remove almost all of the impurities including fats, waxes, pectin’s, ash, chlorophyll’s and xanthophyll’s and also seed fragments this it is an economical process saving both the time and money. Hoe ever, if full white fabric with high degree of whiteness it’s intended then, it is better to perform both the process separately to achieve best results .
Chemical Quantities
Total Liquor 250 m/l
Hydrogen per Oxide 20 m/l
Caustic soda (flex) 20g/l
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Peristal – PSK (con) 6.0 G/L
Prevlin – NIC /Tannix - 15 2.0 g/l
PROCEDURE
1. Prepare liquor according to recipes2. Pad the fabric 3- 5 times at 100% pick up3. Steam the padded fabric in the steamer at 102 C for 20 min4. Take out sample from steamer 5. Finally dry it in an oven
1. Clean your machinery equipment’s /materials and workbench before you leave 2. Ensure the replacement of all equipment’s to their specified storage area 3. Submit your answer to question together with your data. Calculation and result before
the next laboratory /experiment
LAB EXPERIMENT 10 WHITNESS INDEX
To determine whiteness index of bleaching fabric
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Student Name: ___________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date: _____________________
PERFORMANCE OBJECTIVES
Upon the successful completion of this experiment, the students will be able to:
(i) Whiteness index and its measurement (ii) Working of spectrophotometer
MACHINES/MATERIAL REQUIRED
Spectrophotometer Bleached Samples
DISCUSSION
Whiteness index is a measure of the whiteness of the fabric which determines extent of bleaching performed on the fabric. More often, it can be said that, it is quantitative analysis of the amount of natural pigments removed from the cotton or extent of natural color removed from fabric.
More the impurities are removed, higher will be the degree of whiteness and higher will be value of whiteness index.
This degree of whiteness is measured with the help of color measuring spectrophotometer. The principle of operation of this equipment is simply calculation of ratio of the reflected light to incident light from a sample at many points across the visible spectrum. This ratio is called reflectance. Reflectance percentage can be calculated by the formula given below:
Reflectance= reflected light/ incident light x 100
Whiteness index of the normal bleached fabric ranges from 60to 75 or up maximum of 80 degrees. A pure white paper may have a degree of whiteness of about 150. Higher values of whiteness can be achieved with application of Fluorescent Brightening Agent; generally called FBAs.
The simple principle by which these whitening agent increase whiteness is that, they absorb UV light and they emit in the visible (blue region); this phenomenon is generally called Fluorescence.
With the application of FBAs, degree of whiteness of the fabric may be increased up to 120 to 125.
PROCEDURE
1. Turn on the spectrophotometer and set it to specific software.2. Calibrate the spectrophotometer with the tiles provided.3. Select whiteness index to be calculated.4. Clear the fluff, threads and creases (if any) from the sample and fit it properly on the
sample holder.5. Determine the selected whiteness index using spectrophotometer.
TEST RESULTS
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Sample No. CIE Whiteness Index Burger Whiteness Index
2. Discuss effect of FBAs on the whiteness of substrate?
3. Define whiteness index?
FINAL CHECK LIST
1. Clean your machinery equipment/materials and workbench before you leave.2. Ensure the replacement of all equipment’s to their specified storage area.3. Submit your answers to questions together with your data, calculation and result
before the next laboratory/ equipment.
LAB EXPERIMENT 11
Application of fluorescent brightening agents (FBA) by exhaust method
PERFORMANCE OBJECTIVES
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Name: _____________________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date:_____________________
Upon the successful completion of this experiment students will be able to:
i. Understand optical brightening agents and their functionii. Understand the exhaust method of FBA application
MACHINES/MATERIAL REQUIRED
Bleached fabric Ht dyeing or oscillating dyeing machine
CHEMICAL REQUIRED
Fluorescent brightening agents
DISCUSSION
Fluorescents brightening agents are applied in order to improve whiteness of bleached FVA is applied on the fabric intended as pure white or on fabric to be printed FBA molecule absorbs violet light (UA-electromagnetic radiation ranging b/w 320-360nm wavelength ) and remits it in visible region (blue light 400-470nm ) thus increasing the whiteness or brightness of the textile arterial on which is it applied on which it is applied since the bluish white is generally since the bluish white is generally perceived as pure white the FBA have resemblance to the dye molecule structure but are active only in UV region of the electromagnetic spectrum.
Phenomenon in which light of one wave length is absorbed by the substance and re emitted in the wave length region is called fluorescence
A molecules contains alternating single and double covalent bonds electrons in these molecules are the help of FABAs whiteness index or degree of whiteness of the fabric can be increased from 80 to out 120 or 125 but this increase in whiteness will be confined with the pressure of UV light in all light this brighter effect be invisible
Jority of the commonly available FABs are stilbene derivatives.
Typical Recipe
Chemical Quantity
Liquor Ratio 1:20
Leucophore BMF 0.05-0.1%
PROCEDURE
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1.Prepare the bath according to recipe.2.Start the process at 40c3.Treat the fabric at 70-80c for 20-30 min:4.Finally hydro-extract the fabric
Calculations
S.NO Material Quantity
1 Fabric Weight
2 Total Liquor
3 Leucophore BMF
Assessment
Check degree of whiteness index using spectrophotometer
1. Clean your machinery equipment’s /materials and workbench before you leave 2. Ensure the replacement of all equipment’s to their specified storage area 3. Submit your answer to question together with your data. Calculation and result before
the next laboratory /experiment
LAB EXPERIMENT 12 Mercerization
Mercerization of cotton fabric by continuous method PERFORMANCE OBJECTIVES
Upon the successful completion of this experiment students will be able to:
i. Understand process of mercerization and its objectives
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Name: _____________________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date:_____________________
ii. Understand continuous method of mercerization and role of chemical auxiliaries in it
MACHINES/MATERIAL REQUIRED
Caustic soda Mercerol Acetic acid
DISCUSSION
Mercerization is a process in which strength, absorbency and luster of cotton is enhanced by treating with high concentration of caustic soda (NaOH), this treatment brings in structure conformational resulting into reshaping of kidney shaped cross-section of cotton fiber into almost circular. As a result strength, absorbency and luster and of treated fabric is enhanced.
Typical Recipe
Chemical Quantity
TOTAL LIQUOR
CAUSTIC SODA 28-30 Be
MERCEROL QW-LF(liquid)
PROCEDURE
1. Prepare solution according to the recipe & maintain temperature of solution b/w 15-18 c or at room temperature.
2. Saturate / stabilize the fabric in solution with tension for 40-60 seconds.3. Hot rinse the fabric at 80-90c for 15 min then warm at 60 c for 10 min:4. Finally neutralize the pH OF FABRIC WITH ACETIC ACID (1.0ML/LITER) for
1.Clean your machinery equipment/ material and workbench before you leave.2.Ensure the replacement of all equipment’s to their specified storage area.3.Submit your answer to questions together with your data, calculation and results
before the next laboratory/ equipment.
LAB EXPERIMENT 13
To determine surface & core of pH of fabricPERFORMANCE OBJECTIVES
Upon the successful completion of this experiment students will be able to:
(i) Determine the surface & core pH of fabric
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Student Name: ___________________________________ ID No. ____________________
Signature of the lab tutor________________________ Date: _____________________
(ii) Use universal pH indicator (MERK) / phenolphthalein solution(iii) Understand and use pH scale
MACHINES / MATERIAL REQUIED
Dropper with bottle pH meter and pH scale Conical Flask Heating stove Scissors
CHEMICALS REQUIRED
Universal pH indicator (MERK solution) / phenolphthalein solution Distilled water
DISCUSSION
PH can be defined as the measure of degree of acidity or alkalinity. The most convenient way of expressing pH is by the use of pH scale. The term pH scale means, minus logarithm of the molar concentration of the hydrogen ion present in the solution.
PH scale ranges from 0(maximum acidity) to 14(maximum alkalinity), middle value of the scale which is represents neutral point. The acidity increases from neutral towards 0 and alkalinity towards 14.On calculating pH of fabric, it can be calculated both on surface and core of the fabric called surface and core pH respectively.
PROCEDURE
Procedure for the Surface pH:
Pour few drops of universal pH indicator on the specimen Rub it gently for few seconds Observe color change and compare it with the pH scale Note the readings
Procedure for the Core pH:
1. Take appropriate quantity of water based on fabric to water ratio (liquor ratio 1:30)2. Cut fabric into small pieces3. Boil the distilled water for 10 minutes in the conical flask4. Put the fabric into flask and again boil for 10 minutes5. Let the fabric specimen coo, down and check the pH of the solution with pH meter6. Fill the table given below
Assessment:
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Sample No Surface pH Core Ph
1
2
3
4
5
TEST RESSULTS
________
________
________
REVIEW QUESTIONS
1. What is effect of pH of fabric in the coloration process?
________
________
________
2. Why core of pH of fabric is necessary to be determined?
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______________
______________
______________
3. What is the pH of a pretreated cotton fabric?
_____________
_____________
_____________
FINAL CHECK LIST
1. Clean your machinery equipment/materials and workbench before you leave.
2. Ensure the replacement of all equipment’s to their specified storage area.
3. Submit your answers to questions together with your data, calculation and result before the next laboratory/ equipment
