Process for producing transfer printed cotton and cotton blends

A pretreatment system composed of hexamethoxymethyl melamine, p-toluene sulfonic acid, 2-amino-2-methyl-1-propanol, triethylamine, butoxy triglycol, and carboxy vinyl polymeric thickener is disclosed, which through application to the fabric surface by a screen printing technique is highly effective in improving the affinity of cellulose-containing textiles for disperse dyestuffs. Fabrics with prints that are durable to washing are produced by simultaneously heat transfer printing and curing at about 190.degree. C. to 220.degree. C. for 20-30 seconds.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates to the heat transfer printing of fabrics with 
disperse dyes. More specifically it relates to a pretreatment, 
crosslinking system that is useful in the screen printing of 
cellulose-containing textile materials to improve the affinity of such 
textiles for disperse dyestuffs. The method allows the pretreatment to be 
applied to a textile in fabricated garment form. 
(2) Description of the Prior Art 
Heat transfer printing is a process whereby a paper containing disperse 
dyestuffs on the surface is placed in contact with a suitable material and 
heated, so that the sublimable dyes are transferred from paper to fabric. 
Unmodified cellulose cannot be effectively heat transfer printed with 
disperse dyes because of a lack of affinity. Very little dye is adsorbed 
by the cellulose, and this small amount is removed upon washing. This is 
in marked contrast to the effect obtained with some synthetic textiles, 
such as polyester, which have excellent affinity for disperse dyes. 
Lambert, British Pat. No. 1,445,201, has demonstrated that the affinity of 
a cellulose-containing textile for disperse dyes can be improved by 
treatment with a methylated melamine-formaldehyde resin in which there are 
five--CH.sub.2 OCH.sub.3 groups per melamine group. The fabric is printed 
by heating for 3 minutes at 200.degree.-210.degree. C. with transfer paper 
containing disperse dyes. This longer printing time is needed because of 
the use of a weaker catalyst, such as (NH.sub.4)H.sub.2 PO.sub.4, than is 
usually used for resin finishing of cellulose. 
British Pat. No. 1,460,742 teaches that cellulose-containing fabrics can be 
effectively transfer printed with disperse dyestuffs if the fabric is 
impregnated with at least one curable resin containing one or more 
hydroxymethyl, alkoxymethyl or aldehyde groups that are capable of 
reacting with the disperse dyestuffs. The recommended disperse dyestuffs 
contain one or more amino, hydroxy, or N-hydroxyalkylamino groups. 
In all prior work, no system composed of hexamethoxymethyl melamine, 
p-toluene sulfonic acid, 2-amino-2-methyl-1-propanol, triethylamine, 
butoxy, triglycol, and carboxy vinyl polymeric thickener has been employed 
as a pretreatment for fabric by screen printing the formulation onto the 
surface of a cellulose-containing garment so as to increase its disperse 
dye affinity. 
Those systems with methylated melamine-formaldehyde resin and other 
components all teach that the fabric is to be treated by padding with a 
low viscosity formulation. 
SUMMARY OF THE INVENTION 
This invention provides a screen printable pretreatment system for 
cellulose-containing fabrics to improve their affinity for disperse dyes 
upon heat transfer printing. The pretreatment system is composed of 
hexamethoxymethyl melamine, p-toluene sulfonic acid, 
2-amino-2-methyl-1-propanol, triethylamine, butoxy triglycol, and carboxy 
vinyl polymeric thickening agent. It is the object of this invention to 
produce heat transfer printable cotton and cotton blend fabrics with good 
durability of the print to washing. 
It is a further object to provide a method to transfer print a specific 
area of a cellulose-containing garment. A still further object is to 
provide a pretreatment system that will allow the treated fabric to be 
dried at temperatures without premature curing. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
We have found that a pretreatment system consisting of hexamethoxymethyl 
melamine, p-toluene sulfonic acid, 2-amino-2-methyl-1-propanol, 
triethylamine, butoxy triglycol, and carboxy vinyl thickener is highly 
effective in one-sided treatments for producing transfer-printable cotton 
and cotton-polyester fabrics. 
The pretreatment system of the present invention offers the textile screen 
printer the opportunity to heat transfer print cotton-containing fabrics 
with disperse dyestuffs in a dry process instead of printing with pigment 
dyes in a wet process. Inventory control is greatly facilitated because 
print designs are stored on inexpensive papers instead of more expensive 
fabric. 
The pretreatment system is composed of hexamethoxymethyl melamine that may 
be used from about 5 g to about 20 g for each 100 g of printing 
formulation or from 5% to 20%, by weight, of the treatment formulation. 
Concentrations of p-toluene sulfonic acid should be from about 0.05% to 
about 0.2%. The concentration of the 2-amino-2-methyl-1-propanol should be 
from about 0.05% to about 0.2%. The concentration of triethylamine should 
be about 0.5%. Concentrations of the butoxy triglycol should be from about 
1.25% to about 5%. The concentrations of the vinyl carboxy thickener 
should be about 0.5%, and that of isopropanol from about 3.75% to about 
15%. 
Temperatures to achieve drying after screen printing the formulation onto 
the fabric range from about 25.degree. C. to 150.degree. C. Drying times 
may be from 1 minute to 30 minutes; the preferred drying conditions for 
minimum drying time are 1.5 minutes at 150.degree. C.

The following examples further describe the invention. They are given as 
illustrations and thus should not be considered as limiting the scope of 
the invention. 
EXAMPLE 1 
A thickened solution was prepared such that in each 100 g there were 5 g 
hexamethoxymethyl melamine, 0.05 g p-toluene sulfonic acid, 0.5 g 
triethylamine, 0.05 g 2-amino-2-methyl-1-propanol, 1.25 g butoxy 
triglycol, 0.5 g carboxy vinyl thickener, 3.75 g 2-propanol, and 88.9 g 
water. 
Both 50/50 cotton-polyester and 100% cotton interlock fabrics weighing 
approximately 5.2 oz/sq. yd. were used for treatments. Samples were 
treated on one side with the thickened solution containing 
hexamethoxymethyl melamine crosslinking agent by screen printing the 
fabric through a10XX mesh screen. After printing, the fabric was dried for 
5 minutes at 100.degree. C. The add-on was about 4.9%. 
The samples were transfer printed with transfer printing paper containing 
disperse dye on a heat transfer machine with a 15.times.15 inch platen. 
Printing conditions were 204.degree. C. for 30 seconds. Reflectance 
measurements of the samples that were printed with a transfer printing 
paper containing a black dyestuff formulation are shown in Table I. 
TABLE I 
______________________________________ 
Photovolt Reflectance 
Coloration 
Sample Initial 5 washings Initial 
______________________________________ 
100% Cotton 5.0 9.0 Deep 
100% Cotton Control 
14.1 32.7 Light 
50/50 C/PE 5.8 6.3 Deep 
50/50 C/PE Control 
12.0 14.2 Dull 
______________________________________ 
These results demonstrate that the affinity of cellulose-containing fabrics 
is significantly increased by pretreating the fabrics with the thickened 
solution containing 5% hexamethoxymethyl melamine, and that durability of 
the prints to washing is good. 
EXAMPLE 2 
A thickened solution was prepared such that in each 100 g there were 10 g 
hexamethoxymethyl melamine, 0.2 g p-toluene sulfonic acid, 0.5 g 
triethylamine, 0.1 g 2-amino-2-methyl-1-propanol, 2.5 g butoxy triglycol, 
7.5 g 2-propanol, 78.65 g water, and 0.5 g carboxy vinyl thickener. After 
printing the fabrics as in Example I, the fabrics were dried for 5 minutes 
at 100.degree. C. The add-on was about 7%. 
The same procedure for transfer printing the samples as in Example I was 
used. Reflectance measurements of the samples that were printed with a 
black dyestuff formulation are shown in Table II. 
TABLE II 
______________________________________ 
Photovolt Reflectance 
Coloration 
Sample Initial 5 washings Initial 
______________________________________ 
100% Cotton 5.0 8.2 Deep 
100% Cotton Control 
14.1 32.7 Light 
50/50 C/PE 5.1 6.5 Deep 
50/50 C/PE Control 
12.0 14.2 Dull 
______________________________________ 
These results demonstrate that the affinity of cellulose-containing fabrics 
is significantly increased by pretreating the fabrics with the thickened 
solution containing 10 percent hexamethoxymethyl melamine. 
EXAMPLE 3 
A thickened solution was prepared such that in each 100 g there were 20 g 
hexamethoxymethyl melamine, 0.2 g p-toluene sulfonic acid, 0.5 g 
triethylamine, 0.2 g 2-amino-2-methyl-1-propanol, 5 g butoxy triglycol, 15 
g 2-propanol, 58.3 g water, and 0.5 g carboxy vinyl thickener. After 
printing the fabrics as in Example I, the fabrics were dried for 5 minutes 
at 100.degree. C. The add-on was about 17.3%. 
The same procedure for transfer printing the samples as in Example I was 
used. Reflectance measurements of the samples that were printed with 
transfer printing paper containing a black dyestuff formulation are shown 
in Table III. 
TABLE III 
______________________________________ 
Photovolt Reflectance 
Coloration 
Sample Initial 5 washings Initial 
______________________________________ 
100% Cotton 5.0 7.8 Deep 
100% Cotton Control 
14.1 32.7 Light 
50/50 C/PE 4.8 6.4 Deep 
50/50 C/PE Control 
12.0 14.2 Dull 
______________________________________ 
The results demonstrate that the affinity of cellulose-containing fabrics 
is significantly increased by pretreating the fabrics with the thickened 
solution containing 20 percent hexamethoxymethyl melamine. 
EXAMPLE 4 
A thickened solution was prepared such that in each 100 g there were 12 g 
hexamethoxymethyl melamine, 0.12 g p-toluene sulfonic acid, 0.12 g 
2-amino-2-methyl-1-propanol, 0.5 g triethylamine, 3 g butoxy triglycol, 
0.5 g carboxy vinyl thickener, 9 g 2-propanol, and 74.58 g water. 
Both a 50/50 cotton-polyester and a 100% cotton plain jersey knit shirt 
were used for treatments. The garments were treated on the front side by 
screen printing with the solution through a 20 mesh screen. Only one side 
of the garments was treated. The garments were dried for 1.5 minutes at 
150.degree. C. The knit shirts were then heat transfer printed with 
transfer printing paper containing disperse dyestuffs for 30 seconds at 
190.degree. C. The resulting knit shirts had prints with bright deep 
colors in contrast to the dull and light colors on the untreated control 
shirts. After 10 washings, the treated shirts had very good color 
retention for the 50/50 cotton-polyester and fair color retention for the 
100% cotton. This was in contrast to the unacceptable appearance of the 
untreated control shirts. 
These results demonstrate that 100% cotton and especially 50/50 
cotton-polyester knit shirts can be readily treated with the designated 
formulation by means of a screen printing technique to substantially 
increase the affinity of the cellulose-containing garment for disperse 
dyestuffs. Further, it is demonstrated that through the use of screen 
printing techniques any specified area of the fabric can be treated after 
the fabric has been converted into garment form. 
EXAMPLE 5 
The same procedure as employed in Example 4 was used except the treated 
shirts were dried at 25.degree. C. for 30 minutes by means of forced air.