[0001] This invention relates to a cake of soap having display means embedded therein. In
particular, but not exclusively, the invention is intended to relate to cakes of soap
for the use of babies or children.
[0002] Young children, and in particular boys, are reputed to have an aversion to the use
of soap when taking baths. In order to overcome this aversion, soap manufacturers
have attempted to make cakes of soap more appealing for children to use. For example,
it is known to mould the cakes into special shapes, e.g. into the shape of cartoon
characters or the like, which may also be multicoloured.
[0003] It is also known with more expensive cakes of soap not intended specifically for
the children's market, to embed in, or adhere to, the soap display cards or films
displaying, for example, the trade name of the soaps in question. Such display cards
or films remain attached to the soap even after the cake has been repeatedly used.
[0004] An aim of the present invention is to provide a cake of soap having a novel form
of display means adhered to, or embedded in, the soap which changes its display when
heated, e.g. by being immersed in water, in excess of a predetermined temperature.
[0005] According to the present invention a cake of soap having display means adhered to,
or embedded in, the cake, is characterised in that the display means includes at least
one deposit of temperature responsive liquid crystal material which undergoes a reversible
visible colour change when passing through a predetermined temperature of from 25°C
to 45°C, the said deposit(s) being surrounded by at least substantially water-impermeable
covering means.
[0006] The or each deposit of liquid crystal material is intended to undergo a reversible
visible colour change when the cake of soap is either dipped into, or removed from,
bath water at typical bath water temperature.
[0007] Various types of temperature responsive liquid crystal material well known to persons
skilled in the art may be used for the display means. Preferably, however, the temperature
responsive liquid crystal material is thermochromic, displaying so-called "colour
play" (i.e. a reversible change of colour through a range of colours) over a predetermined
temperature range and appearing opaque, e.g. black, at temperatures above and below
the predetermined temperature range. In this case the lowest temperature that the
liquid crystal material displays colour play will be the said predetermined temperature.
By way of example, the colour play temperature range may typically be from 32°C to
45°C, preferably from 35°C to 42°C (i.e. a typical range of bath water temperatures)
so that different colours are displayed for different temperatures within the colour
play temperature range. Alternatively, but less preferably, the liquid crystal material
may be of the type which is normally opaque, e.g. green when backed with a black backing,
at temperatures immediately below said predetermined temperature but which clears
at said predetermined temperature (i.e. the "clearing point") and remains transparent
at temperatures immediately in excess of the predetermined temperature. In this case
a representation behind the or each deposit of liquid crystal material will become
visible as the liquid crystal material is heated from a temperature below, to a temperature
in excess of, its clearing point. Ideally in this case the said predetermined temperature
is chosen to be above normal bathroom air temperature and below the water temperature
used for a normal bath and typically will be in the range from 28°C to 38°C, for example
33°C.
[0008] The display means may serve to display the water temperature of the bath, e.g. by
thermochromic liquid crystal material displaying a different colour in dependence
on the water temperature. Preferably, however, the display means is intended to display
a picture, e.g. of a cartoon character or the like, and/or a product name on colour
change of the temperature responsive liquid crystal material. If the liquid crystal
material is of the type which clears when its temperature passes through the clearing
point, the picture and/or product name is arranged to become visible through the transparent
liquid crystal material when the latter is at a temperature above the clearing point
(i.e. when the cake of soap is immersed in bath water at a temperature above the clearing
point) and to become invisible when the liquid crystal material becomes opaque (i.e.
when the cake of soap is removed from the bath water into air temperature below the
clearing point). If the liquid crystal material is thermochromic, displaying colour
play over a predetermined colour range, the or each deposit of temperature responsive
liquid crystal material is conveniently arranged in a pattern representative of the
picture and/or product name to be displayed.
[0009] The display means is conveniently adhered to the cake of soap with a suitable adhesive,
e.g. an insoluble medically inert adhesive, so that a display surface is visible
when the cake is unused. Less preferably, however, the display means may be completely
embedded in the cake of soap so that a display surface becomes revealed only after
some of the soap material has been dissolved from the cake.
[0010] The display means may conveniently comprise a thin, e.g. 500 µm, laminated display
device having upper and lower surfaces provided by at least substantially water impermeable
material, typically, for example, outer sheets of plastics material.
[0011] Preferably the liquid crystal material is printed onto a carrier sheet, e.g. an inner
surface of one of said water impermeable outer sheets.
[0012] The display means may include printed display matter visible whether or not the cake
of soap is out of, or immersed in, bath water in excess of said predetermined temperature.
[0013] An embodiment of the invention will now be described, by way of example, with particular
reference to the accompanying drawing, in which
Figure 1 is a plan of a cake of soap according to the invention, and
Figure 2 is a sectional view taken on the line II-II of Figure 1.
[0014] Figures 1 and 2 show a cake of soap generally designated by the reference numeral
1, having a rectangular recess in its top surface in which is embedded a rectangular
laminated display device 2.
[0015] The display device 2 comprises an upper transparent sheet 4 of water impermeable
plastics material laminated to a lower sheet 5 of water impermeable plastics material.
The inner surface of the sheet 4 has printed, e.g. screen printed, thereon at least
one deposit of temperature responsive thermochromic liquid crystal material in the
form of a design 6 and, completely underlying the design 6 when viewed from above,
a black backing layer (not shown). The printing "ink" typically comprises microencapsulated
droplets of the liquid crystal material. The sheets 4 and 5 are typically gloss or
matt surfaced PVC which is surface modified to enable specially developed ink systems
to key directly onto the modified surface during printing. Typically the sheets 4
and 5 have a thickness of 240 µm each and the display device has a thickness of about
500 µm. The temperature responsive liquid crystal material is chosen to have a colour
play over a temperature range of from 32°C to 45°C, and preferably from 35°C to 42°C.
Outside this temperature range the liquid crystal material will normally have a black
appearance. The design 6 is only visible from above when the overlying liquid crystal
material displays colour play (i.e. when at a temperature within the colour play temperature
range). Other printed matter (not shown) may be arranged so as to be visible at all
times.
[0016] In use, when the cake 1 of soap is immersed in bath water of normal bath water temperature,
e.g. 39°C, which falls within the colour play temperature range, the liquid crystal
material will display a colour characteristic of that bath water temperature and the
design 6 will be visible from above. On taking the cake of soap out of the bath water,
the temperature of the liquid crystal material quickly falls below the colour play
temperature range so that the liquid crystal material becomes black and merges with
the black backing so that the outline of the design 6 cannot be seen. The cake 1 of
soap is particularly appealing to children and encourages them to use soap when taking
a bath. As with conventional cakes of soap having conventional display cards embedded
therein, the display device 2 will remain adhered to, or embedded in, the cake 1 of
soap as the cake becomes smaller in size during use of the soap. By sandwiching the
liquid crystal material between at least substantially water impermeable sheets 4
and 5, the liquid crystal material is protected from being contacted by bath water
when the cake of soap is immersed therein. The adhesive(s) for laminating the sheets
4 and 5 together and adhering the display device 2 to the cake 1 should not of course
be water soluble.
[0017] The invention may be modified in many ways. For example more than one region or deposit
of liquid crystal material may be provided in the display means. The liquid crystal
material design and black backing layer may be printed on the lower sheet 5 instead
of the upper sheet 4. Alternatively the lower sheet 5 may be dispensed with if, for
example, a water resistant backing ink, e.g. black backing ink, is employed to provide
a complete backing for the display device. This enables a thinner, e.g. 250 µm, display
device to be employed. Instead of the temperature responsive liquid crystal material
being thermochromic and displaying colour play over a colour play temperature range,
the liquid crystal material could be of the type which appears opaque, e.g. green,
at temperatures below a specific clearing temperature (the so-called "clearing point")
and which is transparent at temperatures above the clearing point. With such liquid
crystal material, a specific design of liquid crystal material could be printed so
as to overlie a similar design in a preferably dark, e.g. black, backing ink. A green
surrounding ink, simiar in colour to the opaque liquid crystal material, could be
printed around, so as to blend in with, the design. On clearing of the liquid crystal
material, the dark backing ink would be visible against the surrounding green ink.
Alternatively the surrounding ink could be matched to the colour of the backing ink
so that the design would "disappear" on clearing of the liquid crystal material.
With such liquid crystal material the clearing point of the liquid crystal material
is chosen to be above the typical ambient air temperature in a bathroom when a person
takes a bath but below the minimum bath water temperature that a person would normally
expect to experience. For example the clearing point would normally be between 25°C
to 45°C and preferably between 28°C to 38°C. A typical clearing point temperature
would be 33°C. Instead of displaying a specific design 6 in the form, for example,
of a cartoon character, other information, such as a product name, may be displayed.
It is even possible to arrange for the display device to be a thermometer displaying
bath water temperature when the soap is immersed in the bath water.
1. A cake of soap (1) having display means (2) attached thereto, characterised in
that the display means (2) includes at least one deposit of temperature responsive
liquid crystal material which undergoes a reversible visible colour change when passing
through a predetermined temperature of from 25°C to 45°C, the said deposit(s) being
surrounded by at least substantially water-impermeable covering means (4, 5).
2. A cake of soap according to claim 1, characterised in that said at least one deposit
of liquid crystal material is intended to undergo a reversible visible colour change
when the cake of soap is either dipped into, or removed from, bath water at typical
bath water temperature.
3. A cake of soap according to claim 1 or 2, characterised in that the temperature
responsive liquid crystal material is thermochromic, displaying a reversible change
of colour through a range of colours over a predetermined temperature range and appearing
opaque at temperatures above and below the predetermined temperature range.
4. A cake of soap according to claim 3, characterised in that the said predetermined
temperature range is from 32°C to 45°C so that different colours are displayed for
different temperatures within the colour play temperature range.
5. A cake of soap according to claim 1 or 2, characterised in that the liquid crystal
material is of the type which is normally opaque at temperatures immediately below
said predetermined temperature but which clears at said predetermined temperature
and remains transparent at temperatures immediately in excess of the predetermined
temperature.
6. A cake of soap according to claim 5, characterised in that the said predetermined
temperature is chosen to be in the range from 28°C to 38°C.
7. A cake of soap according to any of the preceding claims, characterised in that
the display means is adhered to the cake of soap with a suitable adhesive so that
a display surface is visible when the cake is unused.
8. A cake of soap according to any of claims 1 to 6, characterised in that the display
means is completely embedded in the cake of soap so that a display surface becomes
revealed only after some of the soap material has been dissolved from the cake.
9. A cake of soap according to any of the preceding claims, characterised in that
the display means comprises a thin, laminated display device having upper (4) and
lower (5) surfaces provided by at least substantially water impermeable material.
10. A cake of soap according to any of the preceding claims characterised in that
the liquid crystal material is printed onto a carrier sheet.
11. A cake of soap according to any of the preceding claims, characterised in that
the display means includes a display which differs in dependence on whether the liquid
crystal material is above or below the said predetermined temperature.