[0001] The present invention relates to liquid, pourable, thickened chlorine bleaching compositions,
based on an aqueous alkali metal hypochlorite solution which has been thickened by
the inclusion therein of a thickening system which comprises at least two different
detergent-active agents.
[0002] Such compositions have been described in the art, e.g. in our British Patent Specification
1 329 086 and our European Patent Specification 0 030 401. A specific example of such
a mixture of two different detergent-active agents is the mixture of a trialkylamine
oxide having one C₈-C₁₈ alkyl group and two C₁-C₁₄ alkyl groups and a fully saturated
C₈-C₁₈ fatty acid soap as described in our British Patent Specification 1 329 086,
and the present invention will be in particular concerned with such a mixture, it
being understood, however, that the present invention is not restricted to these particular
systems, other systems as described in our European Patent Specification 0 030 401
being equally suitable.
[0003] Formulations, prepared with a system according to British Patent Specification 1
329 086 are generally quite satisfactory, and have a viscosity up to about 150 cS
at 25°C. Higher viscosities can also be obtained with these mixtures by varying the
ratio between the trialkylamine oxide and the saturated fatty acid soap and using
certain levels of both ingredients. Thus, products with a viscosity of 300 cS at 25°C
can be obtained to provide increased-viscosity products.
[0004] However, we have found that such products are susceptible to shear, and show an increase
in viscosity at low shear (e.g. less than 20 sec.⁻¹) when the temperature decreases.
When the increase in low shear viscosity, by temperature change, is very high, then
the product can take on unattractive flow characteristics, viz. it can become difficult
to squirt the product from a bottle, and it can become elastic and lumpy. It can furthermore
appear to have poor clinging properties, even though the viscosity at low shear may
be high.
[0005] It is therefore an object of the present invention to provide a liquid, pourable,
thickened chlorine bleaching composition having an increased viscosity at 25°C, and
having an appropriate viscosity at lower temperatures and at low shear. More in particular,
the object of the present invention is to provide such products having a low shear
(plateau) viscosity) of up to 1500 cP, preferably up to 1000 cP and most preferably
between 300 and 1000 cP at a shear of less than 20 sec.⁻¹ at a temperature of below
25°C, especially at 10°C or below, and having a viscosity of 150-700, preferably 200-400
cP at a temperature of 25°C.
[0006] We have now found that these objectives can be achieved by increasing the cloud point
of the thickened products, which is attained by using an increased ratio of the trialkylamine
oxide to saturated fatty acid soap and using a higher total level of these ingredients
in the products.
[0007] We have found that the products should be formulated to have a cloud point of at
least 55°C, preferably at least 60°C, using a weight ratio of trialkylamine oxide
to saturated fatty acid soap of 75:25 to 50:50, and using a total level of trialkylamine
oxide plus saturated fatty acid soap of 1.25 to 3, preferably 1.5 to 2% by weight
of the total composition.
[0008] The compositions of the invention furthermore contain from 1-15% preferably 5-10%
by weight of active chlorine, e.g. of alkali metal hypochlorite, and may contain the
usual additives such as colouring agents, perfumes, buffers, free alkali etc. as e.g.
described in our aforementioned patent specifications. Instead of or together with
the saturated fatty acid soap, a material can be used which generates a fatty acid
in the composition, e.g. a lower alkyl ester of a fatty acid such as isopropyl laurate.
[0009] The invention will further be illustrated by way of Examples.
Example 1
[0010] Thickened liquid chlorine bleaching compositions were prepared having the following
formulations:
[0011] The amounts x and y were varied, and the cloud points of the various formulations
were measured. Also, initial viscosity at 25°C was measured, using an F-tube, the
viscosity being expressed in cS, and the viscosity at low shear (3 sec.⁻¹) was measured
at 25 and 5°C, also after the products had been stored for 3 weeks at 20°C and 6 weeks
at 0°C. These latter viscosities are expressed in cP, and were measured in a Haake
viscometer.
[0012] The following results were obtained:
[0013] These results show that the first formulation has an unacceptable high plateau viscosity
at low shear, the second formulation equally so after storage at 0°C, but the last
two formulations show an acceptable plateau viscosity at all stages. These formulations
have a cloud point of 55 and 65°C resp.
Example 2
[0014] Repeating Example 1, using the following amounts x and y, gave the following results:
[0015] These results show that the product with the cloud point of 65°C has an acceptable
plateau viscosity at low shear, whereas the other product does not have such acceptable
plateau viscosity.
1. A liquid, pourable, thickened chlorine bleaching composition, based on an aqueous
alkali metal hypochlorite solution which has been thickened by the inclusion therein
of a mixture of a trialkylamine oxide having one C₈-C₁₈ alkyl group and two C₁-C₄
alkyl groups and an alkali metal salt of a fully saturated C₈-C₁₈ fatty acid, characterized
in that the composition has a cloud point of at least 55°C and contains 1.25 to 3%
by weight of the trialkylamine oxide plus alkali metal salt of the fully saturated
fatty acid, the weight ratio between the trialkylamine oxide and the alkali metal
salt of the fully saturated fatty acid being from 75:25 to 50:50.
2. A composition according to claim 1,
characterized in that the cloud point is at least 60°C and the amount of trialkylamine
oxide plus alkali metal salt of the fully saturated fatty acid is from 1.5 to 2% by
weight.
