Dyeing polyolefine materials

• Main Authors: ROSENKRANZ MAGNUS, HENSEL WALTER
• Format: Patent
• Language: English
• Published: 30.10.1963
• Subjects: DYEING LEATHER, FURS, OR SOLID MACROMOLECULAR SUBSTANCES INANY FORM; DYEING OR PRINTING TEXTILES; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR; LAUNDERING; TEXTILES; TREATMENT OF TEXTILES OR THE LIKE

Polyolefin materials are dyed by applying from an aqueous bath a vat dye in finely divided form and fixing by the action of heat. The vat dyes should be finely dispersed in the dyebath having a particle size 0.1-3 microns, advantageously with the aid of dispensing agents such as naphthalene sulphonic acid/formaldehyde condensates, sodium H-benzylsulphanitate and sulphite cellulose waste liquor. The dyes may be applied in the form of their vat acids which are prepared by reducing the vat dye conventionally to the leuco dye salts in an alkaline solution containing sodium dithionite, salts of hydroxyalkane-sulphinic acids or their reaction products with ammonia or amines, thiourea dioxide, potassium borohydride or glucose and then liberating the vat acids by neutralising or weakly acidifying with, for example, acetic acid preferably in the presence of dispersing agents of the above mentioned type. The dyes may be applied by impregnation or padding at 40-80 DEG C. and then preferably dried. Fixation is achieved at a temperature between 100 DEG C. and the softening point of the material, heating by means of infrared radiation, hot air, contact with heated rollers or baths of molten metal. If the vat dyes have been fixed on the material in unreduced form finishing may be achieved by rinsing, soaping and drying; otherwise an oxidative treatment with atmospheric oxygen, hydrogen peroxide, alkali metal perborates, persulphates or dichromates, if desired in a hot aqueous bath, is introduced. In the case of the dye being fixed in the form of its vat acid it is preferred that it is first converted to the leuco dye salt with an alkaline reducing bath and then re-oxidised and finished as above. Examples of dyeing fabrics of polypropylene fibres are given. Specification 906,899 is referred to.