Washing Improvements
over the years
After the war, when detergents started appearing in appreciable
quantities on the retail market, it was noted that white cotton goods were
not being washed as white as they should be. This was explained by the fact
that although the active material was able to lift the dirt from the cloth
it could not keep it in suspension. Hence small spots of dirt were being
redeposited uniformly over the whole surface area of the cloth while in the
wash-tub or machine, thus giving the cloth a grey appearance.
Carboxymethylcellulose (CMC)
The sodium salt of carboxymethylcellulose (CMC) had been known to
industry for many years and, in fact, a French patent had been applied for
in 1936,1 using CMC as an additive to washing materials. However, this
patent was not developed extensively until the Second World War, when CMC
was used in Germany on a moderately large scale, initially as an extender
for soap which was in short supply, and then as an additive to the synthetic
detergents being produced as a wartime substitute for soaps. When
intelligence reports on the German industry were published, the use of CMC
as an additive to synthetic detergent powders was noted and investigated and
it was found that this addition eliminated the redeposition problem.
Builders
Despite the considerable advances made in the production of the active
detergent matter, by the end of the Second World War progress in the use of
detergents for heavy-duty (cotton) washing was still relatively slow,
although they had already displaced soaps to a considerable extent in the
field of fine laundering and dish-washing. To improve the heavy-duty washing
properties, manufacturers turned for analogies to the soap industry. Soap
for cotton washing had for many years been 'built' with alkaline materials
such as carbonates, silicates, borax, and orthophosphates. All of these
singly and in combination were tried with moderate success. Condensed
phosphates had started appearing on the market in increasing quantities and
from 1947 onwards heavy-duty detergent formulations were introduced,
initially with tetra sodium pyrophosphate and then with sodium
tripolyphosphate with startling success.
With the advent of CMC and tripolyphosphate builders the detergent
industry established itself and has never looked back. The production
figures of tripolyphosphate in the USA is enlightening.
Table 4
| Production of Sodium
Tripolyphosphate |
| Year |
Tons |
| 1947 |
102,000 |
| 1950 |
280,000 |
| 1959 |
700,000 |
| 1964 |
80,000,000 |
| 1967 |
95,000,000 |
| 1970 |
109,000,000 |
| 1972 |
94,000,000 |
| 1974 |
82,000,000 |
| Taken from the US Department of
Commerce figures |
It will be noted that there is a falling off after 1970. The reason is a
combination of restrictions on and opposition to the use of phosphates, and
also international shortages of raw materials.
|
