Senka, in response to advanced finishing for car upholstery, has started the development and popularization of discharge printing methods and chemicals for polyester car upholstery. A special feature
is a printing paste recipe that gives consideration to the sharpness of the edges of the motif.
1. The processing of polyester car upholstery
The processing of polyester car upholstery is displayed in Fig. 1.
[Fig. 1 Processing of car upholstery]
2. Resist/discharge printing process
In resist/discharge printing with disperse dyes, tin chloride, decroline or alkalis can be used, with alkalis being the most suitable.
When the sharpness of the edges of the motif is important, discharge printing with ground dyeing is suitable, but the results of this are generally inferior. In pad dyeing of the ground color, disperse
dye is alkali soluble in its unfixed state, and so is suitable for discharge printing. However, the recipe of the discharge printing paste must be established in consideration of the sharpness of the
edges of the motif.
3. Preparation of the padding bath for the ground color
| x g |
Disperse dye for the ground color |
| y g |
Water |
| 30g |
Anti-migration agent: common low viscosity sodium alginate (7%) |
| 5g |
pH adjuster: ammonium tartrate |
| 5g |
Succinol CSK: Low-foaming penetrating agent |
| 30-50g |
Senkaemulsyn 300: for level printing, enhanced fixing, and softening of the hand of the texture after drying |
1000cc |
As much anti-migration agent as possible should be added to ensure the sharpness of the edges of the motif. The pH adjuster is effective through its neutralization of the alkali.
4. Preparation of the alkali discharge printing paste
The recipes of the pastes for white and color discharge printing are shown in Fig. 2.
[Fig.2 Recipe for alkali discharge printing paste]
White discharge
printing |
Color discharge
printing |
 |
|
| 50-150g |
50-150g |
Potash/soda ash (1:1) |
| 100-150g |
100-120g |
GTG-01: solubilization accelerator |
| 400g |
400g |
Stock paste |
| 10g |
10g |
Emulsion T-57: discharge accelerator, deepens illumination color |
| - |
x g |
Alkali-resistant disperse dyestuff
(high light fastness) |
| 10g |
- |
Fluorescent brightener |
| x g |
y g |
Water |
|
| 1000g |
1000g |
|
|
5. Stock paste for discharge printing
| GCN-15 (15%): Compounded thickener |
500g |
| Primogum F-30: High-visoscity self-emulsion thickener (o/w emulsion) |
30g |
| Water |
470g |
1000g |
Because a large amount of solubilization accelerator is added to the discharge printing paste, any paste in which changes of viscosity occur easily will suffer a decline in its suitability for printing.
GCN-15 is a product compounded of thickeners with good discharge printing results.
In addition, the simultaneous use of emulsion thickener is effective in improving the workability of printing. At Senka, Primogum F-30 is recommended for use as a turpentine-free emulsion thickener.
The simultaneous use of Primogum F-30 facilitates the blending with the solubilization accelerator and improves the fluidity of the discharge printing paste.
Transferability of the printing paste is improved even in high-speed printing with a rotary-screen, so the alkali discharge printing paste penetrates the base fabric evenly and the dried film is
soft, eliminating problems such as splashing or cracking of the paste.
Primogum F-30 is also effective in the stock paste for direct printing and is used in the penetrating printing of pile fabrics in Japan.
[An example recipe for direct printing]
| x g |
Disperse dye |
| y g |
Water |
| 400g |
Primogum F-100 (10%): compounded thickener |
| 30g |
Primogum F-30 |
| 5g |
Organic acid (malic acid, tartaric acid) |
| 10g |
Resister liquid (anti-reduction agent) |
| 30g |
Senkasalt KS conc (penetrating agent for discharge printing) |
| 20g |
GTP-31 (deepening agent) |
|
| 1000g |
|
6. Fixing conditions
HT steaming is the most suitable fixing method with regard to the discharge ability in alkali discharge printing, but thermosol can also be used for 5 minutes at 190°C
7. In conclusion
The discharge printing recipe outlined above is used in the printing of car upholstery in Japan. Material was collected from practical experiments after requests from several printing firms in 1994.
|