Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-07-08
2001-08-14
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S493000, C524S494000, C523S207000, C523S210000
Reexamination Certificate
active
06274664
ABSTRACT:
TECHNICAL FIELD
The present invention is concerned with granular compositions containing a dye-transfer-inhibiting polymer, for use in particulate detergent compositions.
BACKGROUND AND PRIOR ART
The use of various polymers as dye transfer inhibitors (DTIs) in laundry detergent compositions and rinse conditioners has been described in the prior art. Examples of well-known polymers include polyvinyl pyrrolidone (PVP), and copolymers of N-vinylpyrrolidone and N-vinylimidazole (PVP/PVI), available commercially from BASF, Ludwigshafen, Germany as Sokalan (Trade Mark) HPSO and HP56 respectively.
The polymers may be incorporated into particulate detergent compositions directly, for example, as a solution or dispersion, or by dry-mixing powdered polymer with other particulate components. However, the dry-mixing method can lead to deterioration of powder properties, for example, loss of flow and caking, resulting in poor product dispensing into the wash. Powdered polymers can also be difficult to handle.
Alternatively, the polymer may be premixed or granulated with an inert carrier material or another detergent ingredient before incorporation into the detergent composition.
EP 677 580A (Procter & Gamble) discloses a free-flowing powder of high bulk density which contains 5 to 50% by weight of a PVP/PVI polymer and 20 to 95% by weight of a detergent ingredient selected from aluminosilicate, citrate, silica, carbonate, bicarbonate, silicate, sulphate, phosphate, and water-soluble polymers. The preferred and exemplified detergent ingredient is zeolite 4A.
The present invention is concerned with a granular polymer composition containing a different, novel and highly effective dye-transfer-inhibiting polymer. The novel polymer, supplied as an aqueous solution, displays a tendency to discolour on storage; and if spray-dried gives very hygroscopic granules. The granular polymer composition of the invention simultaneously solves the discolouration problem and provides a convenient method for incorporating the polymer into a particulate detergent composition without handling difficulties and without having a detrimental effect on powder properties.
DEFINITION OF THE INVENTION
The present invention accordingly provides a free-flowing granular polymer composition suitable for incorporation in a particulate detergent composition, the granular polymer composition comprising:
(a) a dye-transfer-inhibiting polymer having the general formula I:
wherein
m indicates the degree of polymerisation,
X is an anion,
R
1
and R
2
are independently hydrogen, alkyl or aryl,
n is an integer within the range of from 1 to 5, and M is a cation;
(b) a carrier material comprising a silica.
The Dye-transfer-inhibiting Polymer
The dye transfer inhibiting (DTI) polymers with which this invention is concerned are water-soluble poly(vinylpyridine betaines) containing a quaternary nitrogen and a carboxylate group. These polymers exhibit particularly effective DTI properties even in the presence of anionic surfactants.
The polymers have the general formula I given above.
Preferred polymers are those in which:
X is a halide, most preferably Cl or Br;
R
1
and R
2
are both hydrogen;
n is 1,
M is alkali metal, most preferably Na or K;
and the polymer is 25-100% quaternised, preferably 75-100% quaternised.
Preferred polymers have a weight average molecular weight of about 5,000 to 1,000,000, preferably 20,000 to 200,000; where m is about 30 to 5,000, preferably 100 to 1,000.
An especially preferred polymer is poly(4-vinylpyridine) sodium carboxymethyl betaine chloride, having the formula II below, which is arrived at from formula I when n=1, R
1
and R
2
are both hydrogen, X=Cl and M=Na.
Specifically, samples of polymer having degrees of quaternisation of 100%, 75% and 50% have been found to have a high level of DTI effectiveness.
Also of interest are copolymers in which the 4-vinylpyridine (VPy) monomer is partially replaced by other polymerisable dye-binding monomers. Preferred dye-binding comonomers are nitrogen-containing heterocycles.
Preferred comonomers include vinyl pyrrolidone (VP), vinyl imidazole (VI), acrylamide, vinyl caprolactam, vinyl azlactone, vinyl azlactam, methyl vinyl imidazole (MeVI), vinyl pyridine-N-oxide (VPy-N-O), vinyl oxazolidone.
Especially preferred comonomers are vinyl pyrrolidone (VP) and vinyl imidazole (VI).
Examples of Such Polymers Include:
a copolymer in which the 4-vinyl pyridine (VPy) monomer is partially replaced by vinyl pyrrolidone (VP) at a ratio of VPy to VP of 50:50, 100% quaternised;
a copolymer in which the 4-vinyl pyridine (VPy) monomer is partially replaced by vinyl pyrrolidone (VP) at a ratio of VPy to VP of 25:75, 100% quaternised.
In addition to or instead of dye-binding comonomers, other comonomers, for example, acrylic-type monomers, may be included, in order to confer additional water solubility or to provide other benefits.
As previously indicated, it has been found that these highly effective DTI polymers, supplied in aqueous solution form, can show a tendency to become discoloured if stored in an alkaline environment, such as obtains in a laundry detergent composition. Furthermore, if the polymer solution is spray-dried, very hygroscopic granules result. The polymers cannot, therefore, readily be incorporated as such into a particulate laundry detergent composition.
The present invention solves both these problems simultaneously by providing a composition in granular form in which the polymer is present together with a silica-based carrier material.
The Silica-based Carrier Material
The carrier material is based on a silica. It has been found that certain silicas are effective to give light-coloured granules of high storage stability, while others are less effective. Without wishing to be bound by theory, it is believed that the silicas that are most effective are acidic, or have a low iron content, or both.
The silica on which the carrier material is based preferably has a 5% solution pH not exceeding 6.0, more preferably not exceeding 5.0. Preferably the silica has a 5% solution pH within the range of from 2.0 to 8.0, more preferably from 2.0 to 6.0 and most preferably from 3.0 to 5.0.
Alternatively or additionally, the silica may preferably have an iron content (maximum) of less than 200 ppm, more preferably less than 150 ppm. Preferably the iron content (as Fe) is from 50 to 200 ppm, more preferably from 50 to 150 ppm.
The contents of other transition metals, for example, titanium, chromium and manganese, may also play a significant role.
5% solution pH values and iron contents for some commercially available silicas are shown below (* denotes Trade Mark). Most other Crosfield commercial silicas have pH values within the 6.0 to 7.0 range.
Values for a commercially available finely divided aluminosilicate, Alusil* ET, are also shown.
pH
Fe content
Manufacturer
(5% solution)
(ppm, max)
Gasil* 200TP
Crosfield
3.2-5.0,
140
average 4.5
Gasil* AB720
Crosfield
5.5-7.5
80
Sorbosil* TC15
Crosfield
5.5-7.5,
420
average 6.3
Sipernat* 50
Degussa
5.0-7.0
230
Alusil* ET
Crosfield
11.0
415
Both precipitated and gelled silicas may be suitable for use as carrier materials in the polymer granules of the present invention.
The most preferred silicas for use in the present invention are Gasil* 200TP and Gasil* AB720.
These silicas may be used alone as carrier materials for DTI polymers in granules according to the present invention.
Advantageously, the silica-based carrier material may also comprise a solid organic, or inorganic acid. If a solid acid is present, a silica material that does not intrinsically have a low pH may be used. Thus the use of a solid acid enables silicas that are not effective alone, for example, Sorbosil* TC15, to be used as carriers in the granular polymer compositions of the present invention.
Solid organic acids are preferred. The acid may be monomeric or polymeric. Examples of solid organic acids include:
aliphatic dicarboxylic acids, for example, adipic acid;
aromatic dicarboxylic acids, for example, phthalic acid;
de Ruijter Hendrik
Emery Derek William
Jones Neil
Strijbosch Antonius Henricus J
Acquah Samuel A.
Mitelman Rimma
Rajguru U. K.
Unilever Home & Personal Care USA , division of Conopco, Inc.
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