Printing on pretreated substrates

In the printing of dyes onto substrates, the pretreatment of the substrates with low levels of calcium or sodium salts or other gelling/insolubilizing agents effectively reduces dye usage.

The use of alginates in textile print pastes is well known. For example, GB 
021,609 teaches a thickener containing sechydroxyalkyl alginate or an 
amine salt of alginic acid, or sechydroxyalkyl alginate mixed with 
derivatives of polymers of acrylic acid or maleic anhydride/ethylene 
copolymers. 
It is also well known that alginates react with bivalent metal cations, 
most notably calcium, to form gels. The combination of algins and calcium 
salts has been disclosed in U.S. Pat. No. 4,222,740 as a means of forming 
dye resist areas on textiles. As taught therein, gelled regions are formed 
by separately applying a gelable (alginate) composition and a gelling 
(calcium) agent composition to a textile and then over-dyeing the 
material, the gelled regions serving as dye resist areas. In another 
embodment, lateral ink spread is taught to be reduced by incorporating a 
dye into either the gellable composition, the gelling compositions, or 
both. The amount of gelling agent taught must be sufficient to gel the 
alginate composition. Specifically, a 5% (by weight) composition is 
recommended, although 1-10% is taught to work. The amount of alginate is 
taught to be from 0.5 to 5% by weight, preferably 1% to 2.5%. 
It has now been found that when very low levels of gelling agent are used 
to pretreat a substrate, the dye usage for equal colour yield is reduced, 
accompanied by improved print definition. 
By alginate is meant the water-soluble derivatives and salts of alginic 
acid which form gels in contact with bi- or ter-valent metal cations such 
as calcium. Alginates are found in all species or Phaeophyceae, brown 
algae. A variety of alginates may be used in the practice of this 
invention. Where a high-viscosity alginate is used, the amount of gelling 
agent is reduced. Likewise, if a low-viscosity alginate is used, the 
amount of gelling agent must be increased. The amount and type of alginate 
used in any particular application will, of course, be dependent on the 
other materials in the print paste, e.g., oxidizing agents, buffers, etc. 
These can be determined by the individual practitioner depending on his 
particular formulation. However, usage levels in the range 0.2 to 6.0% by 
weight are within the scope of this invention; preferably 0.3 to 2.5%. 
Optionally, thickening agents such as guar, locust bean gum, CMC, suitable 
synthetic polymers, and starch ether may be included to provide viscosity. 
The gelling composition comprises water and a soluble bivalent or tervalent 
metal salt, preferably a calcium salt such as the chloride. The amount of 
metal cations used is very low, comparable to the amount obtained by 
preparing a 0.025 to 0.75% by weight (anhydrous) calcium chloride 
solution. When applied to fabrics of differing pick-up capacity, this will 
amount to between 0.03-0.5% calcium (as CaCl.sub.2 anhyd.) based on the 
weight of the fabric. Aluminium and chromium salts, for example, could 
also be used. 
in another embodiment of this invention, the substrate pre-treatment is 
accomplished not with the use of a bivalent or tervalent metal gelling 
agent but with the salt of a univalent metal ion, such as sodium chloride, 
or an organic acid such as citric acid (0.35 to 1.0%). An aqueous solution 
is used comprising 5 to 20% by weight (preferably, 10%) of the chloride, 
nitrate, or sulphate salts of sodium, potassium, or lithium. 
Likewise, alternative thickener/gelling systems, based for example on 
cellulose derivatives such as sodiumcarboxymethyl cellulose, 
galactomannans, such as carboxymethyl guar and de-polymerised guar, and 
starch derivatives, may be used. In such cases appropriate gelling agents 
are aluminium chloride and di-sodium tetraborate. The use of these 
alternative gelling systems provides benefits similar to the alginate 
system in terms of improved definition and reduced print paste 
consumption, but alginate gives a technically superior result and is 
preferred. 
In another embodiment of this invention, instead of using a salt, the 
substrate is pre-treated with 0.1 to 1.0% of a cationic gelling agent. 
These cationic gelling agents include polyhexamethylene biguanide 
hydrochloride. 
The print pastes of this invention are those prepared using disperse dyes, 
reactive dyes, combinations of disperse and reactive dyes, and acid dyes, 
i.e., all anionic or non-ionic dyes but not cationic dyes. Pigment 
printing systems may also be included. The invention is most effective 
with disperse dyes. In addition to the alginate and dye, these print 
pastes comprise a variety of well known compounds such as buffers, 
oxidizing agents, etc. The preparation of such pastes is known in the art. 
In the practice of this invention, the amount of free bivalent or 
tervalent metal cations in the print paste composition should be kept low. 
Therefor if hard water is used to prepare such compositions the use of a 
sequestrant is recommended but at levels low enough not to interfere with 
the gelling reaction. 
The substrates to be treated include, for example, polyesters, cellulosics, 
blends of these, and polyamides. The substrates can be any material which 
can be printed with the appropriate dyes. 
In the process of this invention the substrate is first treated with the 
gelling agent composition of univalent salt composition. Typical 
application techniques are padding, immersing, foaming and spraying. The 
substrate is preferably then dried prior to application of the print paste 
although in some applications either partial or no drying is also 
acceptable. Drying is preferred especially where good definition or colour 
yield is required. The treated substrate may be dyed immediately or stored 
for later use. The print paste composition can be applied by any 
conventional printed or dye method such as flat or rotary screen printing, 
block or raised relief printing, jet printing, stencil printing, engraved 
cylinder printing, Tak dyeing, Kuster dyeing, dip squeeze application or 
hand application. 
When a substrate is treated according to this invention, it is sometimes 
observed that less (about 20-50%) print paste is taken up by the 
substrate. The actual colour intensity achieved will depend upon the print 
paste pick-up and the control of penetration into the substrate but the 
amount of dye actually consumed can be reduced by up to about 40%. 
Following application of the print paste the substrate is treated as 
necessary to fix any dyes, then washed, dried and otherwise treated by 
conventional methods to produce the desired end produce. 
The following examples, which are intended to be illustrative and not 
limiting, further describe the invention and also compare the present 
invention to that of U.S. Pat. No. 4,222,740. In these examples, 
evaluation of the results is done by visual observation of the final dried 
substrate. Percentages are by weight unless otherwise stated.

EXAMPLE 1 
Resist Dye Process--One Dye 
Following the teachings of U.S. Pat. No. 4,222,740, a piece of fabric is 
treated to produce areas resistant to dyeing and then the fabric is 
printed to determine the efficacy of the treatment. 
Polyester knitted fabric is printed with a paste comprising: 
______________________________________ 
Wt. % 
______________________________________ 
Matexil PA-L (sodium-m-nitrobenzene 
1.0 
sulphonate), oxidizing agent 
Mon-sodium orthophosphate, buffer 
0.1 
Manutex M300 (medium viscosity 
3.0 
sodium alginate) 
Water (D.I.) 95.9 
Total 100.0 
______________________________________ 
Manutex is a Trademark of Alginate Industries Ltd., London, U.K. 
The printed fabric is then padded for 30 seconds in a solution containing 
5.0% anhydrous calcium chloride. It is then given a cold-water rinse and 
dried. 
The treated fabric is then over-printed with a print paste constituted as 
above but containing 5.0% Dispersol Blue R-PC (ICI Ltd. Blakeley, 
Manchester, U.K.). Fixation is then carried out by H.T. steam at 
175.degree. C. for 7 minutes. The fabric is then washed in a solution 
containing 1% Calgon PT (sodium hexa-m-phosphate) (Albright & Wilson Ltd., 
Oldbury, Worcestershire, U.K.) followed by a conventional soap and rinse. 
After this treatment the part printed with the alginate solution is 
essentially uncoloured whereas the rest of the printed area is blue, thus 
demonstrating the dye-resist efficacy of this treatment. 
However, when this procedure is repeated using 0.1% calcium chloride 
instead of 5.0%, the treated areas do not resist dyeing and in the 
finished product the blue dye is seen to cover both the gelled and 
non-gelled areas. 
EXAMPLE 2 
Resist Dye Process--Two Dyes 
Following the procedure of Example 1 but using a dye in both the 
pretreatment and in the print paste, another piece of fabric is tested. 
Polyester knitted fabric is printed with a paste comprising: 
______________________________________ 
Wt. % 
______________________________________ 
Dispersol Yellow C-4R Liquid 
5.0 
Matexil PA-L (sodium-m-nitrobenzene 
1.0 
sulphonate) 
Mono-sodium orthophosphate 
0.1 
Manutex M300 (medium viscosity 
3.0 
sodium alginate) 
Water 90.0 
Total 100.0 
______________________________________ 
The printed fabric is then padded (with 70% expression or add-on) in a 
solution containing 5.0% anhydrous calcium chloride. It is then given a 
cold water rinse and dried. 
The treated fabric is then over-printed with a print paste constituted as 
above but with Dispersol Blue R-PC substituted for the yellow dye. 
Fixation is then carried out by H.T. steam at 175.degree. C. for 7 
minutes. The fabic is then washed in a solution containing 1% Calgon PT 
(sodium hexa-m-phosphate) followed by a conventional soap and rinse. 
After this treatment the part printed with alginate/yellow dye is coloured 
yellow, the remainder of the printed area is blue. 
When this procedure is repeated using 0.1% calcium chloride instead of 
5.0%, the treated areas do not resist dyeing and in the finished product 
the blue colour is seen only on the non-gelled areas but a green colour is 
seen in the gelled areas printed with alginate/yellow dye. 
EXAMPLE 3 
Low Calcium Level Pretreatment 
To demonstrate the effectiveness of pretreating substrates with low levels 
of di- or trivalent metal cations, untreated and treated fabrics are 
printed as follows: 
Polyester knitted fabric is padded (with 70% expression) in solutions 
containing 0.025, 0.05, 0.075, 0.125, 0.175, 0.225, 0.275, 0.325, 0.375, 
0.425, 0.475, 0.5, 1.25 and 2.5% anhydrous calcium chloride. 
After drying the treated fabrics were printed with a print paste 
comprising: 
______________________________________ 
Control (for 
nontreated 
Wt. % fabric) Wt. % 
______________________________________ 
Dispersol Rubine C-B liquid (ICI) 
5.0 5.0 
Matexil PA-L, sodium-m-nitrobenzene 
1.0 1.0 
sulphonate) (ICI) 
Mono-sodium orthophosphate 
0.1 0.1 
(Albright & Wilson) 
Manutex RS, high viscosity 
1.5 2.2 
sodium alginate 
Calgon, sodium hexa-m-phosphate 
0.4 0.5 
Water (D.I.) 92.0 91.2 
Total 100.0 100.0 
______________________________________ 
Use of anhydrous calcium chloride at levels up to 0.275% provides improved 
print definition and an increase in colour yield as indicated by a 
significant increase in the sharpness of fine line detail and a greater 
intensity of colour. 
When the fabric is treated with solutions containing anhydrous calcium 
chloride at levels above 0.275% the fabric coverage becomes progressively 
poorer and the colour-yield is reduced. Use of anhydrous calcium chloride 
at 0.15% provides improved print increase in colour yield of 40% compared 
with the untreated control fabric. When the fabric is treated with gelling 
solutions in the range 1.0%-10.0%, fabric coverage is poor and the colour 
yield is reduced by more than 50%. 
EXAMPLE 4 
Pretreatment with Univalent Salt 
Polyester knitted fabric is padded (with 70% expression or add-on) in a 
solution containing 10.0% sodium chloride. After drying, the treated 
fabric is printed with a print paste comprising: 
______________________________________ 
(Conventional 
Wt. % Recipe) Wt. % 
______________________________________ 
Dispersol Rubine C-B liquid 
5.0 5.0 
Matexil PA-L, sodium-m-nitrobenzene 
1.0 1.0 
sulphonate 
Mono-sodium orthophosphate 
0.1 0.1 
(Albright & Wilson) 
Manutex F, low viscosity 
4.5 6.0 
sodium alginate 4.5 6.0 
Calgon, sodium hexa-m-phosphate 
1.1 1.5 
Water (D.I.) 88.3 86.4 
Total 100.0 100.0 
______________________________________ 
The dye is then fixed on the printed material by H.T. steam at 175.degree. 
C. followed by the normal wash procedure and the fabric is dryed. The 
fabric exhibits superior definitions and colour yield.