formaldehyde - Sciencemadness Dot Org

VSES OF FORMALDEHYDE 3U5
and then hot water until all the formaldehyde and acid are remove L IT is
finally dried at 105°C for 30 minute's.
Effects of this type, probably result from a -welling action ui formaldehyde
solution which is made permanent by a minimal amount 01 nif-Thylenic
cross-linking.
Improvements Relating to Dyeing and Dyed Fabrics. A.< previously
pointed out, the affinity of cotton for direct dyes can be slightly increased by
treating with acid formaldehyde in the presence of water*. Improved dye
penetration and fastness are claimed to result when cellulose acetate fabrics
are treated with strong aqueous formaldehyde containing 10 to 30 per cent
by volume of a monatomic aliphatic alcohol at 50°C and then washed free
of the treating solution 6 . It is stated that the effects produced by this
treatment also result from swelling of the fiber which is retained after
treatment. The reduced affinity of cellulose for direct dyes after drvheating
with formaldehyde in the presence of an acid is employed for the
production of two-toned effects in dyed fabrics. According to Bowen and
co-workers 10 , this may be accomplished by printing the fabric with a solution
containing 6 per cent formaldehyde and 0.6 per cent ammonium
thiocyanate, drying at 70°C, baking for 5 minutes at 150*0, and then
dyeing with a direct dye. The treated portions of the fabric are only
slightly colored.
Processes involving formaldehyde and nitrogenous compounds are often
of special value in improving the dyeing characteristics of cellulosic textiles.
A patented process of this type involves treating a regenerated cellulose
fabric with a solution containing formaldehyde, thiourea, and potassium
tetroxalate, drying, baking at 140 to 150°C, washing to remove acid, and
then boiling for 5 minutes with a 4 per cent solution of cyanamide 9 . The
treatment of cellulosic fabrics with formaldehyde and cyanamide or guanyl
guanidine is claimed to make it possible to dye these fabrics readily with
acid wool dyes 15 . Treatment with formaldehyde-urea condensates before
or after dyeing is said to enhance the affinity of the fabric for dyes and improve
fastness. According to Sehneevoigt and Xowak 5 *, local pattern
effects can be obtained by printing treatments involving a roethylol urea.
Cellulose fibers impregnated with a solution containing formaldehyde, a
long chain aliphatic amine, and a tetralkyl ammonium base are also reported
to acquire a good affinity for wool dyes 38 .
Formaldehyde likewise has applications in dyeing with naphthol colors.
Schroy 54 claims that the addition of small amounts of formaldehyde as a
stabilizing agent to a naphtholate bath greatly improves the wash fastness
and insures a uniform affinity of the naphthol dye for cotton and vegetable
fibers.
Improvements in the fastness of some direct dyes to washing and per-