Dyeing of textiles

Details Dyeing of textiles Dyeing of textiles

1999-08-23

2001-03-13

Einsmann, Margaret (Department: 1751)

Bleaching and dyeing; fluid treatment and chemical modification

Organic additive for dye composition, dye composition...

Polymeric additive

C008S555000, C008S556000, C008S606000, C008S685000, C008S686000, C008S918000, C008S920000, C008S921000, C008S930000

Reexamination Certificate

active

06200354

ABSTRACT:

This information relates to the dyeing of textiles, and in particular to the dyeing of pre-treated cellulosic textiles using pre-metallized acid dyes.
It is well known that cellulosic textiles can be dyed with reactive, direct, sulphur, vat and azoic dyes. Other classes of dyestuff, particularly acid dyes, are relatively ineffective in dyeing cellulose substrates because their chemistry does not make them readily substantive to the cellulose fibres.
A recent development in the dyeing of cellulose substrates is a proprietary process known as the Jarofast process, which involves the use of a cationic pretreatment before dyeing with an anionic solubilised sulphur dye, followed by a treatment which removes some of the dye, typically a washing or enzyme treatment step, to produce dyed textile having a “washed out” appearance. This appearance is very fashionable and popular particularly for cotton products such as jeans and related products. The products of this process have a desirable appearance, but the dyeing is not very wash fast and has poor light fastness. Whilst the Jarofast process can be successfully applied to cotton and other similar natural cellulosic fibres, it is less successful in dyeing regenerated cellulosics and does not work at all well on rayon or lyocell materials such as ‘Tencel’ fabrics made from Courtaulds lyocell fibre.
The present invention is based on our discovery that by using a suitable pretreatment of the cellulosic fibres, pre-metallized acid dyes can be applied to cotton and similar cellulosic substrates, including regenerated cellulosics such as rayon and especially lyocell fibre materials such as ‘Tencel’ fabrics, to give well dyed products with good wash fastness and which can give dyed fabric with good “washed out” appearance, which can be enhanced by suitable post-dyeing treatment. Further benefits are that in washing in normal use the level of staining of adjacent fabrics is very much lower than is obtained with fabrics treated by the Jarofast process.
Accordingly, the present invention provides a method of making a dyed cellulosic fibrous material, which comprises the steps of:
1 treating the material with a cationic agent having a plurality of cationic centres;
2 dyeing the material with a pre-metallized acid dye; and
3 optionally treating the material with a cationic polymer.
The substrate treated in this invention is described as a fibrous cellulosic textile material. By this we mean that the substrate is cellulosic or contains, typically, from 30 to 100% fibres of, cellulosic material. Typical cellulosic fibre materials which can be included in such fabrics include natural cellulosic fibrous material such as cotton, flax, jute, hemp and ramie, and synthetic or regenerated cellulosic fibrous material such as rayon particularly viscose and acetate rayon and solvent spun materials, particularly where the solvent is N-methylmorpholine oxide (NMMO) which are often referred to as lyocell materials and in particular the lyocell fibre from Courtaulds and the fabrics made from such fibre sold under the Courtaulds trade name ‘Tencel’. The cellulosic fibre material can be a blend on more than one type of cellulosic fibre or a blend of fibres of cellulosic fibres with non-cellulosic materials and in particular includes blends of cellulosic fibres, particularly cotton, rayon and especially lyocell, fibre with polyester, particularly polyethylene terephthalate polymer or related copolymer, fibre, or with polyamide fibres, including wool, silk and synthetic polyamides such as nylon. The textile can be a woven (including knitted) or non-woven textile, but will usually be a clothing textile material.
The polymeric pretreatment agent used in the invention is cationic and such materials are referred to as cationic polymeric pretreatment agents. The cationic polymeric pretreatment agents are polymer including a plurality of cationic centres and are usually made by polymerisation of monomers containing cationic or potentially cationic centres. Desirably the cationic centres are quaternary nitrogen centres which may be aliphatic quaternary ammonium groups or quaternary aromatic nitrogen centres. The quaternary nitrogen centre may be present as such in the polymeric agent or may be present under application conditions or may be generated in situ after application to the textile. Examples of cationic quaternary nitrogen centres which can be present in the polymeric pretreatment agent include: —N
+
(R)
3
where each R is an alkyl group particularly a C
1
to C
4
alkyl e.g. methyl group, although one or more of the R groups may be a longer chain alkyl group e.g. a C
6
to C
18
alkyl group, or where two of the groups R together with the nitrogen atom bearing them form a heterocyclic ring, particularly a 5 or 6 membered ring, which may include further hetero atoms, such as piperidine, tetrahydropyrrole, piperazine and morpholine rings, which may themselves be further substituted as in N-alkyl e.g. methyl, piperazine rings; or one of the R groups may be a group, typically an alkylene group, linking to another, usually nitrogen, site in the polymer or to another polymer chain; or —N
+
(R′)
2
— where the groups R′ are as defined for R above and the other bonds directly or indirectly link into the polymer chain optionally via a ring, usually a 5- or 6-membered ring; and aromatic quaternary nitrogen centres such as pyridinium.
The degree of cationicity (expressed as cationic centres per units of molecular weight) is generally at least 1 cationic, particularly quaternary nitrogen centre, per 1500 Daltons (D), desirably at least 1 cationic centre per 1000 D, more usually at least 1 cationic centre per 750 D and with the most effective polymers we have tested at least 1 cationic centre per 500 D. The maximum concentration of cationic centres is about 1 per 120 D, desirably not more than about 1 per 150D. (Relative molecular weights are expressed including chloride as a counter ion for cationic centres.)
Expressed as cationic centres per monomer residue in the polymer, the polymer typically has at least about 1 cationic centre per 20, more usually at least about 1 cationic centre per 10, and desirably at least about 1 cationic centre per 5, monomer residues in the polymer. The upper limit is typically 1 cationic centre per monomer residue.
Examples of cationic polymeric pretreatment agents include polymers of diallyldimethylammonium chloride (which polymerises to give a repeat unit including cyclic, 5- and/or 6membered ring including dimethyl ammonium groups)—conveniently referred to under the abbreviation poly-DADMAC (diallyldimethylammonium chloride) such as is available under the trade name Matexil FC-ER from ICI Surfactants, quaternised (co-)polymers of vinylpyridines, such as 4-vinylpyridine, copolymers of dimethylamine and epi-chlorohydrin such as is available under the trade name Fixogene CXF from ICI Surfactants and copolymers of diallyldimethylammonium and diallyl-N-2-hydroxy-3chloro-propylamine (or its protonated ammonium derivative) and copolymers having repeat units of diallylmethylamine (or its protonated ammonium derivative) and diallyl-N-methyl-N-2-hydroxyl3-chloropropylammonium. The charge balancing anions for the quaternary ammonium groups are typically halide, particularly chloride, ions. These latter two copolymers are capable of crosslinking or similar reactions involving the chloride substituent on the propyl group and other nitrogen centres.
The cationic polymeric pretreatment agents used in this invention typically have molecular weights of from 5 to 50 kD and more desirably from 10 to 30 kD.
The use of cationic polymeric pretreatment agents has the advantage that they are strongly substantive to the cellulosic fibres, and are thus readily applied to the textiles, and typical pre-metallized acid dyes are substantive to the treated cellulosic textile material. This can substantially ease application of the dyes to the cellulosic textile material for example reducing or eliminating the need for the use of salts to encourage subst

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