Note: Descriptions are shown in the official language in which they were submitted.
CA 02306397 2000-04-20
An Abrasive Cleaner Containing Microcapsules
Field of the Invention
This invention relates to thickened surfactant- and abrasive-
containing liquid cleaners incorporating microcapsules for cleaning hard
surfaces.
Background of the Invention
Abrasive cleaners are powder-form, liquid or paste-form cleaners
with a high content of generally water-insoluble abrasive components, such
as finely ground silica flour, marble powder and occasionally chalk, feldspar
and pumice stone. In order not to damage the surfaces to be treated, the
abrasive must have a very fine and uniform particle size. In order to
improve cleaning performance, most abrasive cleaners contain surfactants,
phosphates, soda and, optionally, bleaching, disinfecting and deodorizing
agents.
Abrasive cleaners are suitable for cleaning hard surfaces, such as
wood, metals, stoneware, enamel and stone in the domestic and
institutional sectors. Commercially available liquid abrasive cleaners
generally contain marble powder as their abrasive component. By virtue of
its minimal hardness, marble powder does not leave any scratch marks
behind, even on mechanically sensitive surfaces, for example tiles, glass
and enamel.
After storage and transportation, the abrasive cleaner is supposed to
develop its optimal effect on the object to be cleaned at the particular time
of application. This means that the ingredients should not have settled,
decomposed or vaporized beforehand. Elaborate and correspondingly
expensive packs are able to counteract the loss of volatile components and
to protect the abrasive cleaner against penetrating moisture. Chemically
incompatible components can be preserved, for example, by complicated
making-up in separate preparations which then have to be combined for
application which involves an additional step. Light-sensitive ingredients
cannot be packaged in transparent packs which enable the consumer to
CA 02306397 2000-04-20
2
see both the appearance and quantity of the abrasive cleaner.
An elegant method of incorporating sensitive, chemically or physi-
cally incompatible and volatile ingredients is to use microcapsules in which
these ingredients are encapsulated in a storage-stable and transportable
form and from which they are mechanically, chemically, thermally or
enzymatically released for application or during application.
Microcapsules are finely dispersed liquid or solid phases which are
coated with film-forming polymers and in the production of which the
polymers are deposited onto the material to be encapsulated after
emulsification and coacervation or interfacial polymerization. The micro-
scopically small capsules, also known as nanocapsules, can be dried like
powders. In this way, spirit, water, alcohol, pharmaceuticals, solvents,
vitamins, enzymes, liquid crystals, food flavors and perfumes for example
can be converted into a dry material which is unable to dry out.
Microencapsulation is used, for example, for perfume powders which, as
microcapsules, are more convenient to handle and have a longer-lasting
effect.
EP 0 763 595 relates to surfactant-containing structured liquid
detergents which contain a sufficient quantity of salting-out electrolyte to
structure the surfactants and in which "needle-like" solid particles
measuring 3 to 25 pm in at least one direction are said to enable relatively
large particles 200 to 1000 Nm in diameter, for example encapsulated
bleach activators or enzymes, to be converted into a stable suspension.
The total surfactant content is preferably above 20% by weight and
electrolyte is preferably present in quantities of 7 to 45% by weight. The
solid particles, for example calcium citrate, the dihydrate of calcium sulfate
and calcium or magnesium chloride, are not abrasives.
EP 0 328176 relates to surfactant- and electrolyte-containing struc-
tured water-based cleaners containing a suspended phase of surfactant-
containing solid particles and/or non-encapsulated drops which may
contain mineral abrasive particles as another suspended phase. The sus-
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3
pended phase has a higher concentration by weight of surfactant than the
aqueous phase. The total surfactant content is preferably at least 15% by
weight and the viscosity is preferably below 2500 mPa~s and more
preferably 1000 mPa~s at a shear rate of 21 s-'.
EP 0 397 246 describes a powder-form abrasive cleaner containing
85% by weight of abrasives in which perfume capsules up to 100 Nm in
diameter with a water-insoluble brittle shell are present.
The problem addressed by the present invention was to provide
high-performance liquid abrasive cleaners in which the physically or
chemically incompatible or sensitive ingredients would be incorporated in a
temperature-, storage- and transportation-stable, easy-to-handle and visu-
ally attractive form.
Description of the Invention
The present invention relates to a thickened liquid abrasive cleaner
for hard surfaces containing surfactant, abrasive, thickener and
microcapsules in which one or more ingredients are completely or partly
encapsulated.
Quantities expressed as percentages by weight (% by weight) are
always based on the abrasive cleaner as a whole, unless otherwise
indicated.
The microcapsules are chemically and physically stable, more
particularly spatially stable, in the abrasive cleaners according to the
invention, i.e. the microcapsules do not decompose or settle in the abrasive
cleaner.
The microcapsules contain at least one solid or liquid core which is
surrounded by at least one continuous membrane or coating. Accordingly,
in multiple-core microcapsules, also known as microspheres, two or more
cores are distributed in the continuous coating material and single- or
multiple-core microcapsules may be surrounded by an additional second,
third etc. coating. Single-core microcapsules with one continuous coating
are preferred.
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The coating may consist of natural, semisynthetic or synthetic
materials. Natural coating materials are, for example, gum arabic, agar,
agarose, maltodextrins, alginic acid or alginic acid salts, for example
sodium or calcium alginate, fats and fatty acids, cetyl alcohol, gelatine,
albumin, shellac, polysaccharides, such as starch or dextran, sucrose and
waxes. Semisynthetic coating materials are inter alia chemically modified
celluloses, more particularly cellulose esters and ethers, for example
cellulose acetate, ethyl cellulose, hydroxypropyl cellulose, hydroxypropyl
methyl cellulose and carboxymethyl cellulose, and starch derivatives, more
particularly starch ethers and esters. Synthetic coating materials are, for
example, polymers, such as polyacrylates, polyamides, polyvinyl alcohol or
polyvinyl pyrrolidone.
The cores of the microcapsules may be solids or liquids in the form
of solutions or emulsions or suspensions and preferably contain one or
more active substances. Preferred active substances in the context of the
invention are essential oils, for example perfumes, limonene, geraniol or
nerol, components of bleaching systems, for example bleach activator,
enzymes and also care components and protective components for the
hard surface such as, for example, cationic polymers, silicone oils (for the
care of Ceran~ surfaces) or stearyl mercaptan for protecting silver. Other
active substances in the context of the invention are antibacterial agents
such as, for example, benzoic acid, lactic acids, salicylic acid, sorbic acid
or
mixtures or salts thereof. Active substances according to the invention for
improving appearance include dyes, pigments and pearlizing components.
Other active substances in the context of the invention are other
ingredients typically encountered in detergents and cosmetics, including
inter alia dermatologically active substances, such as vitamin A, vitamin B2,
vitamin B12, vitamin C, vitamin E, D-panthenol, sericerin, collagen partial
hydrolyzate, various vegetable protein partial hydrolyzates, protein
hydrolyzate/fatty acid condensates, liposomes, cholesterol, vegetable and
animal oils such as, for example, lecithin, soya oil, etc., plant extracts
such
CA 02306397 2000-04-20
as, for example, aloe vera, azulene, hamamelis extracts, algal extracts,
etc., allantoin, A.H.A. complexes.
The microcapsules may have any shape within production-related
limits, but are preferably egg-shaped or ellipsoidal or substantially
5 spherical. Their diameter along their largest spatial dimension is normally
between 10 nm (visually not discernible as a capsule) and 10 mm or even
larger, depending on the active substance and the application envisaged.
Visible microcapsules with a diameter of 0.01 to 6 mm are preferred, those
with a diameter of 0.05 to 4 mm being particularly preferred and those with
a diameter of 0.1 to 2 mm being most particularly preferred. Microcapsules
invisible to the naked eye preferably have a diameter of 20 to 500 nm and
more preferably in the range from 50 to 200 nm.
The microcapsules may be obtained by known methods, of which
coacervation and interfacial polymerization are the most important.
Any commercially available surfactant-stable microcapsules may be
used as the microcapsules, including for example the commercial products
Hallcrest Microcapsules (coating material: gelatine, gum arabic) from
Hallcrest, Inc. (US), Colefica Thalaspheres (coating material: maritime
collagen) from Coletica (FR), Lipofec Millicapsules (coating material: alginic
acid, agar agar) from Lipotec S.A. (ES), Induchem Unispheres (coating
material: lactose, microcrystalline cellulose, hydroxypropyl methyl cellulose)
and Unicerin C30 (coating material: lactose, microcrystalline cellulose,
hydroxypropyl methyl cellulose) from Induchem AG (CH), Kobo
Glycospheres (coating material: modified starch, fatty acid esters, phospho-
lipids) and Softspheres (coating material: modified agar agar) from Kobo
(US) and Kuhs Probiol Nanospheres (coating material: phospholipids) from
Kuhs (DE).
The active substances are released from the microcapsules for or
during application by mechanical, thermal, chemical or enzymatic
destruction of the coating. In the case of the abrasive cleaners normally
used in undiluted form, they are preferably released by mechanical action,
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6
more particularly by mechanical forces to which the microcapsules are
exposed for this purpose as they leave the pack, for example in a
dispensing or spray valve, for example in the form of shear forces which
crush the microcapsules or - with capsule diameters beyond about 1 mm -
blades which cut through the capsules, and by frictional forces to which the
microcapsules are exposed in the application of the abrasive cleaner.
In one preferred embodiment of the invention, the abrasive cleaners
contain the same or different microcapsules in quantities of 0.1 to 10% by
weight, more preferably in quantities of 0.2 to 8% by weight and most
preferably in quantities of 0.5 to 6% by weight.
Surfactants in the context of the teaching according to the invention
are understood to be one or more anionic surfactants, cationic surfactants,
nonionic surfactants and amphoteric surfactants, more particularly one or
more anionic and/or nonionic surfactants. The total surfactant content of
the abrasive cleaners according to the invention is normally not more than
35% by weight, preferably from 0.1 to 25% by weight, more preferably from
0.2 to 20% by weight and most preferably from 0.4 to 15% by weight.
Suitable anionic surfactants are, for example, C6_22 carboxylic acids
and salts thereof, Cg_~6 alkyl benzenesulfonates or alkyl benzenesulfonic
acids, C~22 alkyl sulfates and C6_22 alkyl ether sulfates containing 1 to 20
(average degree of alkoxylation) ethyleneoxy and/or propyleneoxy units.
Preferred anionic surfactants are unbranched or branched, saturated
or mono- or polyunsaturated Cs_22 carboxylic acids (fatty acids) and salts
thereof, for example alkali metal and alkaline earth metal salts, more
particularly sodium and potassium salts, and ammonium and mono-, di-
and trialkylammonium salts thereof, such as monoethanolammonium salts.
Preferred fatty acids are oleic acid (9-octadecenoic acid), palmitic acid
(hexadecanoic acid), stearic acid (octadecanoic acid) and mixtures thereof,
more particularly palmitic/stearic acid mixtures, preferably in a molar ratio
of about 1:1.
In one preferred embodiment of the invention, the abrasive cleaners
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contain one or more anionic surfactants, more particularly fatty acids and/or
salts thereof, in quantities of 0.1 to 10% by weight, more preferably in
quantities of 0.2 to 8% by weight and most preferably in quantities of 1 to
6% by weight.
Suitable nonionic surfactants are, for example, C6_22 fatty alcohols
and oxoalcohols and products of the addition of ethylene oxide and/or
propylene oxide onto fatty alcohols or oxoalcohols or Cs_22 alkyl
polyglycosides, more particularly alkyl polyglucosides, with a degree of
oligomerization of 1 to 10 and preferably 1.1 to 2.5.
Preferred nonionic surfactants according to the invention are C~22
alkyl polyglycol ethers, more particularly alkoxylated C$_~8 fatty alcohols
containing 1 to 20, preferably 2 to 14 and more preferably 3 to 10 (average
degree of alkoxylation) of ethyleneoxy units (EO) and/or propyleneoxy units
(PO), for example C~0-14 fatty alcohol + 1.2P0 + 6.4E0, C~2_~4 coconut
alcohol + 6E0 or C~2_~4 coconut alcohol + 4E0.
In one preferred embodiment of the invention, the abrasive cleaners
contain one or more nonionic surfactants, more particularly alkyl polyglycol
ethers, in quantities of 0.1 to 10% by weight, more preferably in quantities
of 0.2 to 7% by weight and most preferably in quantities of 0.5 to 5% by
weight.
Suitable amphoteric surfactants are, for example, betaines corre-
sponding to the formula (R~)(R2)(R3)N+CH2C00~, in which R' is a C8_25
and preferably C~0.2~ alkyl group optionally interrupted by hetero atoms or
groups of hetero atoms and R2 and R3 may be the same or different and
represent alkyl groups containing 1 to 3 carbon atoms, more particularly
Coo-~s alkyl dimethyl carboxymethyl betaine and C»_» alkylamidopropyl
dimethyl carboxymethyl betaine.
Suitable cationic surfactants are, for example, quaternary ammo-
nium compounds with the general formula (R4N+)X- more particularly those
in which the nitrogen group is substituted by too long and too short alkyl
groups, for example dimethyl distearyl ammonium chloride.
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The abrasive cleaners according to the invention contain one or
more abrasives. The abrasive is preferably a fine-particle material with a
mean particle size of about 5 Nm to 100 Nm, at most 10% of the particles
having a particle size of more than 150 Nm. The mean particle size of the
particles forming the solid phase is preferably 10 Nm to 80 Nm and more
preferably 10 Nm to 60 Nm, the maximum particle size being below 200 pm
and more particularly below 150 Nm. The mean particle size is based on
the volume distribution of the particles which may be determined by known
methods (for example by the Coulter Counter method).
A water-insoluble, a substantially water-insoluble or a water-soluble
material may be used as the abrasive. The water-insoluble abrasives
which may be used for the purposes of the present invention include, for
example, silica flour, aluminium oxide, marble powder, chalk, pumice stone,
layer silicates and/or feldspar.
Substantially water-insoluble abrasives are, for example, poorly
soluble salts, such as anhydrite, anhydrous CaS04. Anhydrite is distin-
guished in particular by the fact that it is particularly easy to rinse off or
wash off after application of the abrasive cleaner. Preferred anhydrite is
colorless, i.e. is not visibly colored by impurities, and has a mean particle
size as determined by sieve analysis of about 26 pm, about 10% having a
particle size of up to 3.5 Nm and 90% a particle size of up to 61 Nm. One
such anhydrite is commercially available as Calciumanhydrit 8~ from
Siidharzer Gipsvverke.
Water-soluble abrasives are generally water-soluble salts selected
from the group of chlorides, carbonates, hydrogen carbonates, sulfates,
phosphates, borates and silicates. The salts are preferably alkali metal
salts and, more preferably, sodium and/or potassium salts.
Water-soluble abrasives are preferably used where the abrasive
cleaner has a low water content because the use of water-soluble
abrasives in water-containing abrasive cleaners requires that the quantity
of abrasive added exceed the abrasive-based dissolving capacity of the
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water. Accordingly, the use of water-soluble abrasives with increasing
water content of the abrasive cleaner or increasing abrasive-based
dissolving power is increasingly less preferred.
The abrasive cleaner according to the invention preferably contains
one or more water-soluble and/or water-insoluble abrasives, more
particularly from the group of calcium carbonate (for example Durcal~ 15 of
Omya Gmbl-rJ, aluminium oxide (for example Poliertonerde~ P 730 of
Alcoa Chemie) and silica with a ratio by weight of quartz to kaolinite of
74:26 (for example Sillitin~ Z 86 of Hoffmann & Sohne).
The abrasives are preferably present in the abrasive cleaners
according to the invention in quantities of 5 to 80% by weight; more
preferably in quantities of 10 to 70% by weight, most preferably in
quantities of 15 to 60% by weight and, in one particularly preferred
embodiment, in quantities of 20 to 50% by weight.
To adjust their viscosity, the abrasive cleaners according to the
invention contain one or more thickeners.
Thickeners in the context of the present invention are organic natural
thickeners (agar agar, carragheen, tragacanth, gum arabic, alginates,
pectins, polyoses, guar gum, locust bean gum, starch, dextrins, gelatine,
casein), organic modified natural substances (carboxymethyl cellulose and
cellulose ether, hydroxyethyl and hydroxypropyl cellulose and the like, gum
ethers), organic fully synthetic thickeners (polyacrylic and polymethacrylic
compounds, vinyl polymers, polycarboxylic acids, polyethers, polyimines,
polyamides) and inorganic thickeners (polysilicic acids, clay minerals, such
as montmorillonites, zeolites, silicas).
Preferred thickeners according to the invention are xanthan gum (for
example Keltrol~ RD of Kelco, Rhodopol~ 50 MD of Rhone Poulenc),
anionic methacrylic acid/ethyl acrylate copolymer (for example Rohagit~
SD 15 of Rohm Gmbl~ and swelling-retarded hydroxyethyl cellulose (for
example Tylose ~ H 60000 YP 2 of Clariant).
The thickener content of the abrasive cleaners according to the
CA 02306397 2000-04-20
invention is preferably from 0.01 to 10% by weight, more preferably from
0.05 to 6% by weight and most preferably from 0.1 to 3% by weight.
The abrasive cleaners according to the invention may additionally
contain one or more builder components, preferably citric acid (for example
5 citric acid~1 H20) or alkali, more particularly monoethanolamine,
diethanolamine, triethanolamine and/or ammonia, in quantities of 0.01 to
10% by weight and, more particularly, in quantities of 0.1 to 5% by weight.
Depending on the application envisaged, the abrasive cleaners
according to the invention may advantageously contain one or more foam
10 inhibitors, for example natural fats and oils or fatty alcohols, long-chain
soaps (for example sodium behenate), silicone-based defoamers and
symmetrical or asymmetrical dialkyl ethers (for example fatty alcohol
polyglycol ethers etherified with (fatty)alcohols). Preferred foam inhibitors
according to the invention are dimethyl polysiloxane mixtures (for example
Dove Coming~ DB 31 EU of Dow Coming) and carboxylic acid esters (for
example Degressal~ SD 30 of BASF AG). The foam inhibitor content of
the abrasive cleaners according to the invention is preferably not more than
5% by weight and, more preferably, in the range from 0.0001 to 3% by
weight.
The liquid phase of the abrasive cleaners according to the invention
is normally based on water, in which case their water content is in the
range from about 15 to 90% by weight, preferably in the range from 20 to
80% by weight and more preferably in the range from 30 to 70% by weight.
However, their water content may also be less than 15% by weight,
preferably between 0.1 and 10% by weight and more preferably between
0.2 and 5% by weight, particularly in cases where the abrasive cleaners
have a relatively high surfactant content and/or contain water-soluble
abrasives.
The water-based abrasive cleaners according to the invention may
additionally contain one or more non-aqueous solvents, for example
alcohols (methanol, ethanol, propanols, butanols, octanols, cyclohexanol),
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glycols (ethylene glycol, diethylene glycol), ethers and glycol ethers
(diethyl
ether, dibutyl ether, mono-, di-, tri-, polyethylene glycol ether, propylene
glycol monobutyl ether). A preferred solvent is ethanol. These solvents
are preferably present in the abrasive cleaners according to the invention in
quantities of 0.01 to 20% by weight, more preferably in quantities of 0.1 to
12% by weight and most preferably in quantities of 0.5 to 8% by weight.
The viscosity of the abrasive cleaners according to the invention at a
temperature of 22°C and at a shear rate of 20 min-' is preferably in
the
range from 500 to 20,000 mPa~s, more preferably in the range from 1000 to
15,000 mPa~s and most preferably in the range from 1500 to 10,000
mPa~s.
In addition, the abrasive cleaners according to the invention may
contain other typical additives, for example dyes and perfumes,
preservatives, corrosion inhibitors, antistatic agents and microbicides.
The pH value of the abrasive cleaners according to the invention
should be selected according to the particular application envisaged.
Accordingly, the abrasive cleaners may be acidic, preferably with a pH
value of 1 to 6 and more preferably in the range from 1.5 to 4, neutral,
preferably with a pH value of 6 to 8 and more preferably in the range from
6.5 to 7.5, or alkaline, preferably with a pH value of 8 to 12 and more
preferably in the range from 9 to 11. If the required pH value cannot be
established solely by combining the ingredients, it is adjusted by addition of
acid or alkali, for example citric acid or sodium hydroxide.
To produce the abrasive cleaners according to the invention, the
thickener is first thickened in water, after which surfactants and optionally
others of the ingredients mentioned above except for the abrasive
component are stirred in. If perfume and/or dye are used, they are added
last. The abrasive component is then added, the pH value is then
optionally adjusted as described above and finally the microcapsules are
mixed in.
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Specific embodiments of the invention are described in the following
examples which are not to be construed as limiting.
Examples
Abrasive cleaners E1 to E3 according to the invention were
prepared and their pH value and viscosity were determined.
The compositions of abrasive cleaners E1 to E3 in % by weight and
the properties determined are shown below. The pH value of abrasive
cleaners E1 to E4 according to the invention was adjusted to the indicated
values of 2.5 and 10 with citric acid and sodium hydroxide, respectively.
The viscosity was measured with a Brookfield RVT series 3227 rotational
viscosimeter using spindle 4 at a shear rate of 20 min'' and a temperature
of 22°C.
In abrasive cleaners E1 to E4, the capsules were stable over 3
months at 40°C. There was no sign of any change in the shape of the
capsules or in their spatial distribution in the abrasive cleaner.
In the manual application of abrasive cleaners E1 to E4, the
microcapsules were readily destroyed to release the active substances by
the abrasive frictional forces.
Example 1
Abrasive cleaner E1 for hard surfaces in the home
Composition
of
E1
in
% by
weight
(a) C~2_~4 coconut alcohol + 6E0 2
(b) C~o_~4 fatty alcohol + 1.2P0 + 6.4E0 1
(c) Calcium carbonate 41
(d) Methacrylic acid/ethylacrylate copolymer,0.3
anionic
(e) Monoethanolamine 0.2
(f) Dimethyl polysiloxane/emulsifier mixture0.0003
(g) Perfume +
(h) Green microcapsules with perfume Lipotec~5
(i) Water to 100
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13
pH value 10
Viscosity [mPa~s] 4,000
The Lipotec~ microcapsules had a mean diameter of 2 mm and
contained a perfume in aqueous polyethylene glycol- and glycerol-
containing medium in a coating of alginic acid and agar.
After storage for three months, the perfume was still clearly
noticeable to the user in practical application whereas a comparison
abrasive cleaner which contained the perfume in the liquid phase instead of
perfume capsules had considerably less perfume after the same time.
Example 2
Abrasive cleaner E2 for Ceran~ hobs
Composition of E2 in % by weight
(a) C~2_~4 coconut alcohol + 4E0 3
(b) Aluminium oxide Alcoa~ P 730 32.5
(c) Xanthan gum 0.25
(d) Magnesium aluminium silicate, hydrated 1
(e) Ethanol 5
(f) Carboxylic acid ester 1
(g) Citric acid ~ 1 H20 4.25
(h) Perfume +
(i) Blue microcapsules Hallcrest~ DlHC 188 4
with silicone oil
(j) Water to 100
pH value 2.5
Viscosity [mPa~s] 2,500
The Hallcrest type D/HC 188 microcapsules had a diameter of 50 to
100 Nm and contained about 38% by weight of water and as a care
component for Ceran hobs about 58% by weight of silicone oil in the form
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14
of a dimethyl cyclosiloxane pentamer/polydimethyl siloxanol mixture of the
type marketed by Dow Corning as Dow Corning~ 1401 Fluid in a coating of
about 4% by weight of gelatine and gum arabic.
Whereas the incorporation of the silicone oil in the liquid phase of
the abrasive cleaner would have involved the additional use of an
emulsifier to prevent the silicone oil from sedimenting, the introduction of
the silicone oil component in the form of microcapsules was possible
without any problems.
Example 3
Abrasive cleaner E3 for metal surfaces in the home
Composition of E3 in % by weight
(a) Oleic acid 4.8
(b) Palmitic acid/stearic acid mixture 0.2
(molar ratio 1:1 )
(c) Silica (quartz: kaolinite = 74:26) Sillitin~22.5
Z 86
(d) Hydroxyethyl cellulose, Tylose~ H 60000
YP 2 1
swelling-retarded
(e) Ethanol 1
(f) Citric acid ~ 1 H20 2
(g) Ammonia 1.5
(h) Red microcapsules containing stearyl 3.5
mercaptan
(i) Blue microcapsules containing perfume 2.5
Lipotec~
(j) Water to 100
pH value 10
Viscosity 2,500
[mPa~s]
The microcapsules (h) had a mean diameter of 1 mm and contained
about 35% by weight of water and about 60% by weight of stearyl
mercaptan as silver protectors in a coating of about 5% by weight of
gelatine and gum arabic.
CA 02306397 2000-04-20
The Lipotec~ microcapsules (i) had a mean diameter of 0.8 mm and
contained a perfume in aqueous glycerol-containing medium in a coating of
alginic acid and agar.
After storage for 3 months, the perfume was distinctly noticeable to
5 the user in practical application whereas a comparison abrasive cleaner
which contained the perfume in the liquid phase instead of perfume
capsules had a far weaker perfume after the same period.
