What is Cationic Polyester?
Cationic Polyester refers to cationic dyed (dyeable) polyester. The abbreviation of cationic polyester is PBT or CDP.
PBT is a specialty or modified polyester, which is produced by charging macromolecules with the cationic dyeable group. As a result, CDP can be dyed with cationic dyes at the temperature of 110℃. The conventional polyester can only be dyed at a temperature of 130℃.
Why need CDP?
Polyester fiber belongs to the hydrophobic synthetic type. It lacks functional groups that can be combined with direct dyes, acid dyes, and basic dyes. Although the ester group can form hydrogen bonds with disperse dyes, the polyester molecular chain structure is tight, and the dye molecules are not easy to enter the inside of the fiber. As a result, it is difficult for regular polyester fibers to be dyed, and their color and luster are very monotonous.
Due to high crystallinity, there is only a small gap beside the polyester fiber. When the temperature is low, the molecular thermal movement changes its position to a small extent. Under wet conditions, the polyester fiber will not increase the gap by violent swelling like cotton fiber, so it is difficult for dye molecules to penetrate into the fiber. Dyeing of polyester fibers is usually done only with disperse dyes and must be under high temperature and pressure or with the help of a carrier.
From the above, we can see regular polyester (polyethylene terephthalate) has the disadvantage of low moisture absorption, poor dyeing performance, easily accumulating static, and easily fuzzing. Cationic polyester is designed to overcome these defects.
How to produce CDP?
Nowadays the commonly used method is adding dimethyl isophthalate with polarity-based SO3Na into the polyester chips. The filament spinning from this way looks similar to the common one. However, thanks to the use of ion modification, this method not only greatly improves the fiber color absorption performance, but also reduces the crystallinity. As a result, the dye molecules are easy to penetrate into the fiber. Then the dyeing property, color absorption, and hygroscopicity are remarkably improved.
We are an expert on cationic dyeable polyester chips. For more information, please contact us.
Why is higher -COOH as end groups are desirable in Cationic chips over the normal Polyester chips ?
Dear Mr. Rajesh Jalan. Thanks for your comments. Generally speaking, the -COOH (End Group) content in the Cationic chip is lower than that in the normal PET chip. Lower End Group in Cationic Chips is good for the uniform dying. But if you need a higher End group in Cationic Chip, we can customize it for you.
How to identify CDP with solvent
Could you provide more information about your question? Like, identify CDP from Which yarn? We have sent an email to your email address. For the further discussion, please check your email box. Thanks in advance!
what are changes required during polyester chips manufacturing to get higher draw force as well as elongation during melt spinning for filament production . Means some polyester chips getting high draw force and high elongation .So what are chemical or properties of chips required to change to get the same during melt spinning ?
Thanks a lot for your comment on our website.
As far as we know, the easiest way to improve the two factors lies in the spinning processing method.
But if you need some changes in polyester chips, we can add some flexibility monomer or chain.
Hope this information could help you.
And we have already sent you one email regarding this question. Reply to us, if you need more help.
very informative content ..
I am keen to know more about the cationic polyester and the mills doing such fabrics in piece dyed and prints in India and China
Thanks for your comment and very glad to hear this article is informative for you.
We will send you emails to discuss more details with you.
could you let us know which one is having better color fastness?
Cationic Polyester has the better color fastness.
can cationic poly be converted to recycled poly and vice versa?]
Thanks for your question.
We do not think it can.
Hi, Could you explain a bit further your last answer. Why can’t you recycle CDP ? ( both chemically and mechanical recycling )
In a mixed cotton-polyester fabric, is it possible to dye in a single bath with reactive dye by pad batch process if the polyester yarn is cationic?