Chemistry

about 70% problems in dyeing are to to pretreatment . some time there are blander one which one can not believe. it can cause lcr . it can cause variations batcher to batcher variation some time variation causes to to grey fabric fault.

for stains on fabric a dying person thinks very frequently that these are stains that comes during vat dying. But no sir there are certain units which have ability to have stains during reactive dying. it may have several reasons. pre-treatment fault water used in dying brand of antimigrating agent cleaning of machines in vat dyeing stains may come from pad steam. dispersing agent and anti foaming agent are added to avoid stains from pad steam. sodium alginate and primasol FFAM are better to use in vat dyeing to avoid stains. Chilled water is very necessary in vat dyeing on padsteam. trough temperature should be less than 25 degree at any cast other wise problem can occure.

we can not ignore the effect of combination selected for dying on LCR. if compatibility of dyes is not matched with each other it will cause LCR, tonal difference in left , centre, right.

mostly used machines in Pakistan are Monfort. these machines have a problem with LCR .it may have several reasons but peoples which are working on these machines very well know these machines causes LCR especially in twills. Bruckner thermosol is working in Pakistan very well known dying unit . no doubt it have many draw backs but in case of LCR this machine is very good.

pH has markable effect on fabric and shade . Mostly shade are very sensitive towards pH.They change their hue from red to green side or from blue to yellow side . or some time from green blue side to reder yellower side . This depends upon the combination selected. The pH of the fabric should be neutral near to 7.some time for speacial finish pH should be 4-5. But if pH of the fabric as low as 2-3. It will damage the strength of the fabric and your boss will say fabric ki behen nikal the hai.

the most common problem during dying on thermosol is LCR. that may have the following reasons. preparation of fabric. thermosol padder pressure problem. dosing in trough should be uniform. there should be cold water circulation in trough jaket. I.R should be properly working. circulation of air in chambers should be uniform. thermosol should be properly clean after every fifteen days. TAILING EFFECT when we run the shade .after 400 to 500m it changed it hue and depth .this is called tailing effect.this is due to substantivity of dyes. it depends upoun the combination of dyes and range of dyes selected. also parameters of machine have very important role in this respect. FACE BACK face back depends upon the antimigrating agent used .its brand and quantity. the effeciency of I.R. speed of the production. parameters of machine.

There are three method for continous reactive dyeing. pdc pdps w/w PDC in pad dry cure process the axuliries used other than dyes are soda ash and sodium bicarbonate, antimigrating agent ( FFAM , solidicol n,...) and urea and some time wetting agent also. the fabric first passed through the color then dry at 120 to 130 degree. Then cure at 150 to180 degree tempreture . this is a good process and is most commonly used in several dying units. this process is simple but it causes poor light fastness as well as washing festning. to avoid this dificulty padry pad steam process is used. PDPS PROCESS IN this process deyes and axiliries are padded on thermosol , not cured .the axiliries used on thermosol are antimigrating ahent and wetting agent .the dyes are fixed on padsteam , padded with NaOH 6 to 8g/l, and soda ash 20g/l and common salt 250 g/l . then fabric is passed through steamer . 1 min is enough for fixation. W/W THIS DIRECT DYING ON PAD STEAM . in this process ,dyes , sodium b

dyeing of textile goods The most common methods to dye textle goods are exaust method and continous method. Here we will discuss continous method in which mostly thermosol and padsteam are used. The dyes used for cotton are comonly reactive dyes and vat dyes. For polyester , disperse dyes are used. The reactive dyes mostly consist of levafix ca , cibacron p, cibacron c dyes ,drimarin cl dyes. drimarin k dyes and drimarin HFCD range.The following is the Monfort Continous dying range.

chemisty chemistry is very interesting subject.it deal with chemical bahavior of substanses. it has many branches as listed organic chemistry inorganic chemistry analytical chemistry physical chemistry applied chemistry nuclear chemistry bio chemistry textil chemistry envirmental chemistry first we will discuss some basics things about chemistry . The pH it have very important roll in our life. most of our body functions and so many industrial process around us based on pH. to understand pH we first have to know about acids and bases. acid: an acid is a spcies that provide H+ ion in aquas media or which accept a lone pair of electrons. i.g HCl,H2SO4 HCl-------->H + + Cl - here H+ is an arhenus acid.begause it provides a H+ ion. base: a base is species that provides -OH ions in aquas media, or which donates a lone pair of electron.i.g NAOH, kOH NAOH-------->Na + + OH- here NaO