The dyeing of polyester/polyurethane blends involves many difficulties (dyeing reproducibility, dyestuff specking, inferior fastness) that currently remain unsolved. In order to solve these problems, our company, being a manufacturer of dyestuffs, has developed new dyestuffs (MPL and MP series) and new dyeing system auxiliaries (scouring, leveling, anti-staining, soaping and one-bath reduction clearing agents) which have now entered the market.

MPL, MP dyestuff series

Six new products supplemental to Kayalon Polyester (KP) dyestuffs which have entered the market include, in the MPL series, the trichromatic colors of KP Yellow MPL, Rubine MPL and Blue MPL which emphasize fastness, and Red MPL which emphasizes reproducibility, and in the MP series include Navy Blue MP and Black MP.

Kayalon Polyester Yellow MPL
Kayalon Polyester Red MPL
Kayalon Polyester Blue MPL
Kayalon Polyester Rubine MPL
Kayalon Polyester Navy Blue MP
Kayalon Polyester Black MP

1. Characteristics

1. While disperse dyestuff's staining of the polyurethane can be kept low during dyeing, soaping and reduction clearing, the bleeding of dyestuff during heat setting is pronounced and can stain the polyurethane, halving the effectiveness of the different treatments, but with dyestuffs of the MPL and MP series, the bleeding of solvent after heat setting and the bleeding of resin due to water-repellent finishing is much less than that with existing disperse dyestuffs, as they have very good fastness after heat setting.

2. Dyestuffs of the MPL series have good light, sublimation, and post-processing fastness, favorable dyeing speed, temperature and pH dependencies and build-up properties, and also good dyeing reproducibility.

2. Dyestuff's solvent bleeding and fastness

See Table 1.

3. Testing of dyeing speed

Dyeing speed (80°C120°C) is determined according to the combination of KP Yellow MPL, Red MPL and Blue MPL used.

Test item: Polyester/polyurethane (85:15) blend

4. Temperature dependency

See Table 2.

5. pH dependency

See Table 3.

6. Points in the dyeing of polyester/polyurethane blends

•Scouring agent: Kayascore MP
Scouring: This scouring agent is effective in the removal and emulsification of large amounts of fabric oiling agent, and as it contains a nonionic surfactant, it does not cause degradation of the fibers or reduction of the fastness of the dyestuff.

•Anti-staining agent for polyurethane: Kayaresister MP
Staining: Kayaresister MP reduces the amount of staining of polyurethane by disperse dyes.

•Leveling agent: KP Leveller MP
Level dyeing: This product does not reduce the dispersing properties of the dyestuff and has a good leveling ability.

•Soaping agent: Kayasoaper MP
Washing: This soaping agent can effectively wash off dyestuffs that stain polyurethane, and can prevent redeposition.

•One-bath reduction clearing agent: Reductant MP
Reductant: This reductant preserves its reducing power.

•MP, MPL dyestuff series
Dyestuff: These dyestuffs have good reproducibility, low bleeding after heat setting and good fastness.

7. Testing conditions

Test material:	Polyester/polyurethane blend (85:15)
Scouring:	80°C, 30 min, liquor ratio of 1:20 Scouring agent: Kayascore MP 3g/L Soda ash 1g/L hot rinsingcold rinsing
Dyeing:	125°C, 40 min, liquor ratio of 1:20, pH of 4.5 KP MPL dyestuff X% o.w.f. KP Leveller MP 0.5g/L Kayaresister MP 3.0g/L
Reduction clearing:	85°C, 15min, bath ratio of 1:20 Kayasoaper MP 3.0g/L Reductant MP 4.0g/L (Black: 6.0g/L) added at 80°C Note: Sometimes when the polyurethane content is high, or when the depth of the dyeing is high, staining cannot be sufficiently eliminated. In these cases, reduction clearing implemented twice or alkali soaping before reduction clearing can be effective.

Conclusion

While the technical data presented and formulas recommended here are based on our company's most recent information, the data is based on limited laboratory testing and so reproducibility on all possible scales and in all possible applications is not guaranteed. For example, there is a wide range of fabrics among polyester/polyurethane blends, and the effectiveness of soaping differs from machine to machine, so please conduct preliminary testing in all cases.