Nippon Kayaku (Thailand) CO., LTD.
Technical Service Center[Visualization of CDP fiber embrittlement]
The following methods can be used to confirm CDP embrittlement:
1. Measure the tenacity of fiber.
2. Observation with scanning microscope.
① CDP② CDP pH 3
Before dyeing
After dyeing③CDP pH 3, Na2SO4 3g/L
After dyeing

・If CDP fibers become embrittled, the fibers will be damaged as shown in Image ②.
・CDP-dyed fabrics in this state are fragile and can easily be torn.
・With the addition of 3g/L of Na2SO4 under the same dyeing conditions as ②, embrittlement was not observed(Image ③).
・ Fiber tenacity can be measured by hand or by using a tenacity measurement device, but we do not have thisdevice in our laboratory.
・ It can be confirmed with a scanning electron microscope, but it is not a common device, and it does not seemto be provide quantitative data.

NIPPON KAYAKU (THAILAND) CO., LTD.
ADD: 13th Floor, Ramaland Building, 952 Rama IV road, Suriyawongse, Bangrak, Bangkok 10500
TEL: +66-2-235-2843 HP: http://www.kayakuth.co.thVisualization of CDP fiber embrittlement
Effect of CDP dyeing conditions on the color of KP light Scarlet G-S 200 disperse dye

Inorganic salt

pH 4.2pH 2.9pH 3.2(Acetic acid + Sodium Acetate)(Kayaku Buffer CDP 2g/L)(Acetic Acid 1cc/L)

Reference

120℃ x 60 min
dyeingNa2SO4 3g/L

NaCl 3g/L

130℃ x 60 min
dyeingNa2SO4 3g/L

NaCl 3g/L

・ As shown in this image, some disperse dye structures have the property of dyeing embrittled CDP dark.
・ At Nippon Kayaku, one of our disperse dyes KP Light Scarlet G-S 200 has this property.
・ In this confirmation test, the reference was dyed in a liquor ratio of 20:1, pH 4.2, Glauber’s salt 3g/L, 120℃×60 min.
From the data above we confirmed the following:A) Effect of pH:
The lower the pH, the greater the embrittlement. (Embrittlement can occur at acetic acid pH).
B) Effect of addition of Glauber’s salt (Na2SO4) and table salt (NaCl):
Both Glauber’s salt and table salt are effective in preventing embrittlement.
C) Effect of dyeing temperature:
Embrittlement is greater at 130℃ than at 120℃.
・ If embrittlement is large, the hue becomes extremely dark and can be judged with the naked eye.
・ The degree of embrittlement can be judged by the color difference value (D) to the standard dyed fabric shownin the image above.

NIPPON KAYAKU (THAILAND) CO., LTD.
ADD: 13th Floor, Ramaland Building, 952 Rama IV road, Suriyawongse, Bangrak, Bangkok 10500
TEL: +66-2-235-2843 HP: http://www.kayakuth.co.th

・When CDP embrittlement is large, the fabriccan be easily torn by hand.

・Since the test was conducted forembrittlement in dyeing, further processing
such as additional correction dyeing cancause further embrittlement.

・ In addition, the phenomenon that KP Light Scarlet G-S 200 is dyed dark to CDP is not observed withpolyester. Therefore, the conclusion is that the dye was not damaged by the lower pH, but that there are certain
disperse dye structures that can dye damaged CDP to dark.

Effect of Polyester dyeing conditions on the color of KP light Scarlet G-S 200 disperse dye

Inorganic salt

pH 4.2pH 2.9pH 3.2(Acetic acid + Sodium Acetate)(Kayaku Buffer CDP 2g/L)(Acetic Acid 1cc/L)

130℃ x 60 min
dyeingNa2SO4 3g/L

NIPPON KAYAKU (THAILAND) CO., LTD.
ADD: 13th Floor, Ramaland Building, 952 Rama IV road, Suriyawongse, Bangrak, Bangkok 10500
TEL: +66-2-235-2843 HP: http://www.kayakuth.co.thEffect of embrittlement of CDP fibers on fastness (Trichroma)
1. Light fastness of embrittled CDP dyed fabric (Trichroma)
Inorganic salt

120℃ x 30 min

pH 4.2pH 2.9pH 3.2(Acetic acid + Sodium Acetate)(Kayaku Buffer CDP 2g/L)(Acetic Acid 1cc/L)Na2SO4 3g/L

dyeing

NaCl 3g/L

130℃ x 30 min

Na2SO4 3g/L

dyeing

NaCl 3g/L

・ When CDP is embrittled, the light fastness deteriorates, as denoted by a red circle.
・ Addition of Glauber’s salt or table salt to the dye bath reduces the embrittlement of CDP fibers, so almost no
decrease in light fastness is observed.
・ The CDP dyed fabrics marked with a red circle can easily be torn by hand. The tenacity is reduced due to CDP
embrittlement.
No addition ofGlauber’s Salt (Na2SO4)

inorganic salt

3 g/L

Table Salt (NaCl)
3 g/L

pH 4.2pH 2.9pH 3.2pH 4.2pH 2.9pH 3.2pH 4.2pH 2.9pH 3.2

acetic acid +Buffer CDP

acetic acidacetic acid +Buffer CDP

acetic acidacetic acid +Buffer CDP

acetic acidsodium acetate

2 g/L

1 cc /L

sodium acetate

2 g/L

1 cc /L

sodium acetate

2 g/L

1 cc /LNIPPON KAYAKU (THAILAND) CO., LTD.
ADD: 13th Floor, Ramaland Building, 952 Rama IV road, Suriyawongse, Bangrak, Bangkok 10500
TEL: +66-2-235-2843 HP: http://www.kayakuth.co.th2. Light fastness of embrittled CDP dyed fabric (Black)
Effect of CDP dyeing conditions on Light fastness (ISO Xenon-Arc Grade 4 irradiation, judged with Grey scale)

Inorganic salt

pH 4.2pH 2.9pH 3.2(Acetic acid + Sodium Acetate)(Kayaku Buffer CDP 2g/L)(Acetic Acid 1cc/L)-

120℃ x 60 min
dyeingNa2SO4 3g/L

NaCl 3g/L-

130℃ x 60 min
dyeingNa2SO4 3g/L

NaCl 3g/L・ In the case of black dyed fabric, no deterioration in light fastness was observed even under CDP embrittlement
dyeing conditions.
・ In addition, the degree of embrittlement was less than that of the fabric dyed with the trichroma in the previoussection.
・ We initially speculated that the pH of the dye bath had changed due to the increase in dye concentration, andchecked the pH of the dye bath, but there was no change in pH.
・ We speculate some kind of Na compound exists in the additives used in the preparation of the dye composition.
As the amount of black dye used is relatively higher, it can be assumed that the amount of Na from the additives isalso higher, thus assisting in suppression of CDP embrittlement.
・ Although no decrease in light fastness was observed, it does not mean that the CDP is not embrittled. As a basis
for this, the results of the dry rubbing fastness test are shown on the next page.

NIPPON KAYAKU (THAILAND) CO., LTD.
ADD: 13th Floor, Ramaland Building, 952 Rama IV road, Suriyawongse, Bangrak, Bangkok 10500
TEL: +66-2-235-2843 HP: http://www.kayakuth.co.th3. Rubbing Fastness of embrittled CDP dyed fabric (Black)
Effect of CDP dyeing conditions on Dry Rubbing fastness (after R.C.)
Recipe: KAC Black MG-ED(N) 7.0%o.w.f.
Inorganic salt

pH 4.2pH 2.9pH 3.2(Acetic acid + Sodium Acetate)(Kayaku Buffer CDP 2g/L)(Acetic Acid 1cc/L)-120℃ x 60 min
dyeingNa2SO4 3g/L

NaCl 3g/L-

130℃ x 60 min
dyeingNa2SO4 3g/L

NaCl 3g/L

・ As the scanned image does not reflect actual fastness results observed on white fabric, we have also attached apicture of the fastness results taken by a smartphone below. The results marked with a red circle are subpar.
120℃×60 min dyeing: Dry Rubbing
130℃×60 min dyeing: Dry Rubbing

・ The inferior dry rubbing fastness comes from torn fibers of embrittled CDP, not staining from dye.
NIPPON KAYAKU (THAILAND) CO., LTD.
ADD: 13th Floor, Ramaland Building, 952 Rama IV road, Suriyawongse, Bangrak, Bangkok 10500
TEL: +66-2-235-2843 HP: http://www.kayakuth.co.th

・ Although we could not observe deterioration of light fastness due to CDP embrittlement with black dyes, wecould confirm the embrittlement through rubbing fastness.
4. Final Comments
・ It is believed that the Na ions, instead of the sulfate ion, contributes to the inhibition of embrittlement of CDPfibers, as both Glauber’s salt and table salt are effective according to the results above.
・ Simply adding Glauber’s salt can minimize the risk of embrittlement. In addition, it is presumed that theadditional dyeing process for hue correction (correction dyeing) will further deteriorate the tenacity of CDP
fibers through embrittlement, so it is recommended to minimize the risk as much as possible.

NIPPON KAYAKU (THAILAND) CO., LTD.
ADD: 13th Floor, Ramaland Building, 952 Rama IV road, Suriyawongse, Bangrak, Bangkok 10500
TEL: +66-2-235-2843 HP: http://www.kayakuth.co.th