U.S. patent application number 12/845197 was filed with the patent office on 2011-03-17 for process and mould for thermoforming containers.
This patent application is currently assigned to RECKITT BENCKISER (UK) LIMITED. Invention is credited to GEOFFREY ROBERT HAMMOND, RICHARD ROGERS.
Application Number | 20110062308 12/845197 |
Document ID | / |
Family ID | 9898291 |
Filed Date | 2011-03-17 |
United States Patent
Application |
20110062308 |
Kind Code |
A1 |
HAMMOND; GEOFFREY ROBERT ;
et al. |
March 17, 2011 |
PROCESS AND MOULD FOR THERMOFORMING CONTAINERS
Abstract
The present invention relates to a method of manufacturing
water-soluble containers using a horizontal intermittent motion
thermoforming machine which comprises the steps of: a) locating a
first water-soluble film over a mould, said mould containing a
plurality of pocket forming cavities, defined by side walls and a
base, in a 2-dimensional array, each cavity being surrounded by a
planar surface of the mould on all sides in which the shortest
dimension of the planar surface between two adjacent cavities is at
least 3 mm and between an edge of the mould and the closest cavity
is at least 1.5 mm; b) thermoforming the first film to produce a
plurality of pockets; c) at least partially filling the pockets
with a composition; and d) sealing the plurality of the at least
partially filled pockets. The cavities are positioned in the array
such that there are a plurality of continuous strips of
uninterrupted planar surface of the mould from a leading to a
trailing edge of the mould, for receiving support means fitted to
the machine for supporting the film.
Inventors: |
HAMMOND; GEOFFREY ROBERT;
(EAST YORKSHIRE, GB) ; ROGERS; RICHARD; (NORFOLK,
GB) |
Assignee: |
RECKITT BENCKISER (UK)
LIMITED
SLOUGH-BERKSHIRE
GB
|
Family ID: |
9898291 |
Appl. No.: |
12/845197 |
Filed: |
July 28, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10362615 |
Nov 29, 2004 |
7797912 |
|
|
PCT/GB2001/003826 |
Feb 24, 2003 |
|
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12845197 |
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Current U.S.
Class: |
249/119 |
Current CPC
Class: |
B29C 51/18 20130101;
B65B 9/042 20130101; B29C 51/002 20130101; B32B 1/02 20130101; B29C
51/30 20130101; Y10T 428/1352 20150115; B29K 2995/0062 20130101;
B29K 2995/0059 20130101; B29C 51/261 20130101; B65B 47/02
20130101 |
Class at
Publication: |
249/119 |
International
Class: |
B28B 7/24 20060101
B28B007/24 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2000 |
GB |
0020964.3 |
Claims
1-20. (canceled)
21. A mould for use in a thermoforming process for manufacturing
water-soluble containers from water-soluble films, in which said
mould contains a plurality of pocket forming cavities, defined by
side walls and a base, in a 2-dimensional array, each cavity being
surrounded by a planar surface of the mould on all sides in which
the shortest dimension of the planar surface between two adjacent
cavities is at least 3 mm and between an edge of the mould and the
closest cavity is at least 1.5 mm, and in which the cavities are
positioned in the array such that there are a plurality of
continuous strips of uninterrupted planar surface of the mould from
a leading to a trailing edge of the mould.
22. A mould as claimed in claim 21 in which the depth of the
cavities lies in the range of 10 to 80% of the shortest dimension
of the cavity mouth.
23. A mould as claimed in claim 21 in which the depth of the
cavities lies in the range of 40 to 60% of the shortest dimension
of the cavity mouth.
24. A mould as claimed in claim 21 in which the cavity bases are
planar.
25. A mould as claimed in claim 21 in which the cavity bases are
rounded.
26. A mould as claimed in claim 25 in which the rounded bases have
a radius of 20 mm.
27. A mould as claimed in claim 21 in which corners formed where
the cavity side walls meet each other are rounded.
28. A mould as claimed in claim 27 in which the side wall corners
have a radius of 10 mm.
29. A mould as claimed in claim 21 in which edges formed where the
cavity side walls meet an upper surface of the mould are
rounded.
30. A mould as claimed in claim 29 in which the side wall-mould
upper surface edges have a radius of 1 mm.
31. A mould as claimed in claim 21 in which bottom corners, formed
where the cavity side walls meet the cavity base, are rounded.
32. A mould as claimed in claim 31 in which the side wall-base
bottom corners have a radius of 10 mm.
33. A mould as claimed in claim 31 in which air bores are located
in the side walls base bottom corners.
34. A mould as claimed in claim 33 in which the air bores have a
diameter of 0.1 mm to 1 mm.
35. A mould as claimed in claim 34 in which the air bores have a
diameter of 0.4 mm to 0.5 mm.
36. A mould as claimed in claim 21 in which the shortest dimension
of the planar surface between two adjacent cavities lies in the
range of 4 mm to 10 mm and between an edge of the mould and the
closest cavity lies in the range of 2 mm to 5 mm.
37. A mould as claimed in claim 21 in which a continuous strip of
uninterrupted planar surface is provided between adjacent rows of
cavities.
38. A mould as claimed in claim 21 in which a continuous strip of
uninterrupted planar surface is provided between every other pair
of adjacent rows of cavities.
39. A mould as claimed in claim 21 in which air bores are
located.
40. (canceled)
Description
[0001] The present invention relates to a method of manufacturing
water-soluble containers and a mould for use therein.
[0002] It is known to package chemical compositions which may be of
a hazardous or irritant nature in water soluble or water
dispersible materials such as films. The package can simply be
added to water in order to dissolve or disperse the contents of the
package into the water.
[0003] For example, WO 89/12587 discloses a package which comprises
an envelope of a water soluble or water dispersible material which
comprises a flexible wall and a water-soluble or water-dispersible
heat seal. The package may contain an organic liquid comprising,
for example, a pesticide, fungicide, insecticide or herbicide.
[0004] It is also known to package detergents in water-soluble or
water-dispersible containers. For example, WO 94/14941 discloses a
water-soluble or water-dispersible capsule containing an aqueous
dishwasher detergent. The capsule is made of gelatin.
[0005] CA-A-1,112,534 discloses a packet made of a water-soluble
material in film form enclosing within it a paste-form, automatic
dishwasher-compatible detergent composition. The water-soluble
material may be, for example, polyvinyl alcohol, polyethylene oxide
or methyl cellulose. Example 1 illustrates an embodiment wherein a
poly(vinyl alcohol)(PVOH) film is made into a 5 cm square packet by
heat sealing its edges, and the packet is filled with a composition
which contains 8.5 wt. % water.
[0006] In fields such as detergents for domestic use, an attractive
appearance for an article is extremely desirable. However in the
prior art, such as that described above, a bag is simply formed
from a single sheet of water-soluble film. The film is folded and
the edges heat-sealed to form the bag. The bag is then filled and
heat-sealed. This produces a rather flat, limp envelope containing
the product. Furthermore there may be a lack of uniformity between
different bags because of their flexible nature.
[0007] We have discovered that this type of product is not deemed
to be attractive by an average consumer.
[0008] It is known to form water-soluble containers by
thermoforming a water-soluble material. For example, WO 92/17382
discloses a package containing an agrochemical such as a pesticide
comprising a first sheet of non-planar water-soluble or
water-dispersible material and a second sheet of water-soluble or
water-dispersible material superposed on the first sheet and sealed
to it by a continuous closed water-soluble or water-dispersible
seal along a continuous region of the superposed sheets. It is
stated to be advantageous to ensure that the package produced is
evacuated of air or the contents are under reduced pressure to
provide increased resistance to shock. Furthermore, when the
package contains a liquid, the liquid must be an organic liquid
which must be reasonably dry and typically contains less than 2 to
3% of water to ensure that it does not attack the water-soluble
package and cause leakage.
[0009] EP-A-654,418 describes self-standing flexible pouches which
may contain, for example, liquid detergent compositions for
refilling other containers. In order to avoid folding of the pouch,
which can lead to cracking and leakage, the bag is inflated before
it is sealed.
[0010] In order to improve the strength of packages containing
liquids, it is also known to provide the package with residual
inflatability. Thus, for example, EP-A-524,721 describes a
water-soluble package which contains a liquid, wherein the package
is inflatable to a volume which is greater than the initial volume
of the package. Thus the package is filled to less than its
complete capacity, and the unused capacity may be partially, but
not totally, filled with a gas such as air. The unused capacity
which does not contain gas provides the residual inflatability.
[0011] We have now surprisingly discovered a water-soluble
container which contains a liquid composition can be given an
attractive three-dimensional appearance by using a thermoforming
technique, such as that disclosed in WO 92/17382, on a PVOH film
and ensuring that the liquid composition has a reasonably large
water content of at least 3 wt % free water, based on the weight of
the aqueous composition. Immediately after the containers are
prepared, they have a limp, unattractive appearance. However, after
storage for a short while, for example, from a few minutes to a few
hours, they develop a more attractive three-dimensional appearance,
and also appear to look fuller. They can also be said to have a
"puffed-up" appearance. Although not bound by this theory, it is
believed that the water in the aqueous composition shrinks the PVOH
film around the liquid composition to provide the attractive
appearance. In other words the PVOH film attempts to recover its
original shape when contacted with the aqueous composition.
[0012] In our co-pending application entitled "Improvements in or
Relating to Aqueous Compositions" we describe a process for
producing a container as defined above which comprises the steps
of: [0013] a) thermoforming a first PVOH film to produce a pocket;
[0014] b) filling the pocket with the aqueous composition; [0015]
c) placing a second PVOH film on top of the filled pocket; and
[0016] d) sealing the first film and second film together.
[0017] The method of forming the container is similar to the
process described in WO 92/17382. A first PVOH film is initially
thermoformed into a mould to produce a non-planar sheet containing
a pocket, such as a recess, which is able to retain the aqueous
composition. The pocket is generally bounded by a flange, which is
preferably substantially planar. The pocket may have internal
barrier layers as described in, for example, WO 93/08095. The
pocket is then filled with the aqueous composition, and a second
PVOH film is placed on the flange and across the pocket. The second
PVOH film may or may not be thermoformed. The pocket may be
completely filled, or only partly filled, for example to leave an
air space of from 2 to 20%, especially from 5 to 10%, of the volume
of the container immediately after it is formed. Partial filling
may reduce the risk of rupture of the container if it is subjected
to shock and reduce the risk of leakage if the container is
subjected to high temperatures.
[0018] The films are then sealed together, for example by heat
sealing across the flange. A suitable heat sealing temperature is,
for example, 120.degree. C. to 195.degree. C., for example
140.degree. C. to 150.degree. C. A suitable sealing pressure is,
for example, from 250 kPa to 800 kPa. Examples of sealing pressures
are 276 kPa to 552 kPa (40 p.s.i. to 80 p.s.i.), especially 345 kPa
to 483 kPa (50 p.s.i. to 70 p.s.i.) or 400 kPa to 800 kPa (4 to 8
bar), especially 500 kPa to 700 kPa (5 to 7 bar) depending on the
heat sealing machine used. Suitable sealing dwell times are at
least 0.4 seconds, for example 0.4 to 2.5 seconds. Other methods of
sealing the films together may be used, for example infra-red,
radio frequency, ultrasonic or laser solvent, vibration,
electromagnetic, hot gas, hot plate, insert bonding, fraction
sealing or spin welding. An adhesive such as water or an aqueous
solution of PVOH may also be used. The adhesive can be applied to
the films by spraying, transfer coating, roller coating or
otherwise coating, or the films can be passed through a mist of the
adhesive. The seal desirably is also water-soluble.
[0019] It is, however, extremely difficult to manufacture products
using PVOH and other materials having similar physical
characteristics, partly because of their hygroscopic nature, but
mainly due to the fact that the material is very soft and floppy,
making it extremely difficult to handle and cut. In most
thermoforming, vacuum forming or other similar forming processes,
the films used have a degree of strength and rigidity. Thus
friction drives are generally, although not exclusively, used to
support the films and to transport them through the machine during
the process. PVOH and similar films do not have this strength or
rigidity and would stretch, thin and tear if subjected to such
handling.
[0020] Furthermore, thermo- and other such forming processes impose
a significant amount of drawing and stretching of the material. As
such the known method of thermoforming using PVOH materials
utilises a single mould for each moulded product, with each PVOH
film placed manually over each mould. This means that the amount of
material available for deforming is greater, but it is a very
labour intensive, slow and therefore costly process to achieve the
manufacture of this type of product.
[0021] We have discovered that standard horizontal intermittent
motion thermoforming machines, such as those supplied by Multivac,
Doyen and Tiromat, can be used to produce thermoformed containers
from PVOH and films of a similar nature at normal production
speeds. However, some modifications must be made to these machines,
in particular to the drive system, in order to run such films at
normal production speeds.
[0022] It is therefore an object of the present invention to
provide an improvement in the process for manufacturing such
containers, to enable a plurality of water-soluble containers to be
formed simultaneously. A further objective is to provide a tool for
use in a process for producing a plurality of water-soluble
containers made from PVOH or other films of a similar physical
nature or the like, at each stroke of an horizontal intermittent
motion thermoforming machine. Yet another objective is to provide
an improved process for producing multiple containers on a
production scale.
[0023] The invention therefore provides a process for producing a
water-soluble container using a horizontal intermittent motion
thermoforming machine which comprises the steps of: [0024] a)
locating a first water-soluble film over a mould, said mould
containing a plurality of pocket forming cavities, defined by side
walls and a base, in a 2-dimensional array, each cavity being
surrounded by a planar surface of the mould on all sides in which
the shortest dimension of the planar surface between two adjacent
cavities is at least 3 mm and between an edge of the mould and the
closest cavity is at least 1.5 mm; [0025] b) thermoforming the
first film to produce a plurality of pockets; [0026] c) at least
partially filling the pockets with a composition; and [0027] d)
sealing the plurality of the at least partially filled pockets,
wherein in which the cavities are positioned in the array such that
there are a plurality of continuous strips of uninterrupted planar
surface of the mould from a leading to a trailing edge of the
mould, for receiving support means fitted to the machine for
supporting the film.
[0028] The invention further provides a mould for use in a
thermoforming process for manufacturing water-soluble containers
from water-soluble films, in which said mould contains a plurality
of pocket forming cavities, defined by side walls and a base, in a
2-dimensional array, each cavity being surrounded by a planar
surface of the mould on all sides in which the shortest dimension
of the planar surface between two adjacent cavities is at least 3
mm and between an edge of the mould and the closest cavity is at
least 1.5 mm, and in which the cavities are positioned in the array
such that there are a plurality of continuous strips of
uninterrupted planar surface of the mould from a leading to a
trailing edge of the mould.
[0029] The invention will now be described, in further detail, by
way of example only, with reference to and as shown in the
accompanying drawings in which:--
[0030] FIG. 1 is an end elevation of a mould used in the present
invention;
[0031] FIG. 2 is a side sectional elevation of the mould of FIG. 1
on the line I-I;
[0032] FIGS. 3 to 5 are respectively plan views and cross sectional
side elevations of a section of the mould of FIG. 1 showing the
dimensions of the cavities;
[0033] FIG. 6 is a plan view of the mould of FIG. 1; and
[0034] FIG. 7 is a schematic representation illustrating a support
rail;
[0035] FIG. 8 shows support rails supporting a web of material on a
horizontal intermittent thermoforming machine.
[0036] FIGS. 1 and 2 show a mould 10 used for thermoforming a
plurality of containers from PVOH or films having similar physical
characteristics on a horizontal intermittent thermoforming machine
comprising a series of stations as shown in FIG. 7. These are the
forming area 30, at which the film 31 is supplied from a reel to
the moulds 10 and where the first thermoforming step takes place to
form pockets; the filling station 32, at which the pockets are
filled; the sealing station 33, to which a further film 34 is
supplied to seal the pockets; the cooling station 35; and the
cutting station 36 where the sealed containers are separated from
each other by shear knives 38.
[0037] Each mould 10 comprises a 2-dimensional array of pocket
forming cavities 11. Although the Figures illustrate a regular
array of 6.times.7 cavities 11 to form 42 containers
simultaneously, the number and relative positioning of the cavities
11 may be varied. Essentially the surface dimensions of the mould
are determined by the width and draw of the machine on which it is
to be used. The best arrangement of the individual cavities 11 is
determined according to the following considerations.
[0038] Each cavity 11 must be surrounded by a planar surface 18 on
all sides, to allow for subsequent sealing of the second film to
the first films. This dimension should be at least 1.5 mm, but is
preferably in the range of 2 mm to 5 mm. Thus the distance between
any cavity and the edge of the mould 10 is at least 1.5 mm and the
distance between any two cavities 11 is at least 3 mm. The maximum
distance is obviously determined by the size of the mould 10, but
in practice, for commercial reasons, the spacing would not normally
exceed 15 mm.
[0039] As the materials used are very flexible, the web of film
tends to sag. In order to enable all of the cavities 11 to be
filled, support means must be fitted to the machine, from the end
of the thermoforming station to the start of the filling station,
and also preferably to the cutting station 36, to support the web
of film. The support means may be provided by rails, bars,
filaments, wires, rope, cable or the like. Most preferred are wires
or rails. Where rails 1 are used, as shown in FIG. 7, the leading
ends of the rails may have a smooth cam surface 2 for lifting the
web. The support means can be intermittent or, more preferably,
continuous.
[0040] FIG. 8 shows how the web is drawn down from the
thermoforming station by being held by grippers 3 which are pulled
apart to provide some tension in the web. Too much tension will
displace the thermoformed pockets. However, not enough tension is
provided so that the web remains flat for filling. The support
rails 1 maintain the web as a substantially flat surface. This
places an extra constraint on the arrangement of the cavities
within the space available i.e. there must be clear channels 21
(see arrows Z on FIG. 6) through the pattern of cavities 11 from
the leading edge of the mould 10 to the trailing edge. It is
preferred that these channels 21 are available between each cavity
11 (across the web i.e. on the leading edge), but this is not
essential, depending on the number of cavities 11 across the
leading edge. At least every other cavity should be supported.
[0041] Located in the mould 10 beneath the cavities 11 are air
channels 15, which communicate with the cavities 11 via air bores
16. The number and positioning of the air bores 15 has an effect on
how the film is drawn into the cavities 11 during the thermoforming
process, and therefore consideration must be given to an
appropriate arrangement of air bores depending on the specific
configuration of the cavities 11 used. In particular they must be
designed and arranged to effect the most even deformation of the
film into the cavities 11. In a preferred embodiment the air bores
15 are located in the regions where the end and side walls 12, 13
of the cavities 11 join the cavity base 14. The holes are
preferably of 0.1 mm to 1 mm diameter and more preferably 0.4 mm to
0.5 mm. Vacuum release bores 17 are drilled in the cavity bases
14.
[0042] The shape of the cavities 11 is dictated partly by the
intended use of the containers, but also by the processing
constraints. A particularly convenient shape for an automatic
dishwasher composition is illustrated in FIGS. 3 to 5. The
dimensions of the cavities are determined by the required fill
volume of the containers and any constraints resulting from the
intended use of the containers. For example, if the containers are
to be used as refill sachets for a trigger spray, the width of the
containers, and therefore the cavities is determined by the
diameter of the spray bottle neck. If the containers are to be used
for a dishwasher product, all three dimensions are determined by
the dispenser into which the containers will eventually be
placed.
[0043] One particularly suitable embodiment which we have found for
a dishwasher product has a rectangular cavity mouth, the dimensions
of which are 29 mm.times.39 mm, with rounded corners, having a
radius R.sub.1 of, preferably, 10 mm.
[0044] The depth of the cavities depends partly on the area of the
cavity mouth, to ensure that the film, can be drawn down without
over thinning and tearing. This can also be affected by the area of
film available between adjacent cavities 11. Referring to FIG. 6,
the upper surface 18 of the mould 10 can clearly be seen. The gaps
between the cavities 11 are marked as dimensions X and Y in this
particular layout. The ratio X:Y is desirably 1:2 to 2:1,
preferably 1.5:1 to 1:1.5, most preferably about 1:1. X and Y are
desirably from 5 to 13 mm, preferably 7 to 12 mm, preferably about
10 mm. The preferred depth is in the range of 10 to 80% of the
shortest dimension of the cavity mouth, and more preferably in the
range of 40 to 60%. A preferred depth of the cavities 11 where the
mouth of the cavities 11 is 29 mm by 39 mm is 16 mm.
[0045] The corners 19 formed where the end and side walls 12,13 of
the cavities 11 join the cavity base 14, are preferably radiussed
to avoid over thinning or tearing of the film, as it is drawn down
the side walls 13 and the corners 19. The corners 19 preferably
have a radius R.sub.2 and R.sub.3 of between 8 mm and 10 mm.
[0046] The cavity base 14 may be planar or rounded. Especially
where a greater cavity depth is used, such as 18 mm or 19 mm, it
may be preferable to have a rounded base 14 to prevent regions of
thicker material from being drawn directly downward to the centre
of the base 14. A suitable radius for the base 14, in particular
where the cavity depth is 18 mm, is 20 mm. The use of a rounded
base 14 means that the positioning and direction of the air bores
16 may be different from those used with flat-bottomed cavities 11.
This changes the way in which the film is drawn into the cavities
11.
[0047] The edges 20, where the cavity end and side walls 12,13 join
the upper surface 18 of the mould 10, are preferably rounded to
allow for a smooth movement of the film over the edges 20 during
the thermoforming process, to minimise the risk of the film
snagging or tearing. The radius R.sub.4 is preferably small, e.g. 1
mm, as it is difficult to fill this area of the cavities 11 without
risk of fouling the sealing area.
[0048] Another dimension which must be carefully controlled to
enable the film to be drawn into the cavities 11 without tearing,
is the spacing between the cavities 11. For cavities of the
dimensions given above, it is preferred that the spacing between
the cavities lies in the range of 9 mm to 16 mm.
[0049] The draft angle of the side walls 12, 13 is preferably
3.degree. to 5.degree. to assist in the release of the containers.
However, for certain very soft materials, such as PVOH, draft
angles may not be necessary.
[0050] The sizing of the mould 10, incorporating an array of
cavities 11 in this manner, enables the film to be supported. The
width of the web of film is determined by the width of the machine
in which the mould is fitted. The mould is designed to fit the
width of the machine with a suitable "overhang" of film, which can
be used for transporting the film. It is suggested that small clips
or grippers attached to a plurality of driven chains would enable
the films to be transported appropriately. The grippers preferably
toe-out to provide tension as the web of film moves through the
machine.
[0051] A first PVOH film is thus positioned over the mould 10 and
thermoformed in a known manner to form a plurality of pockets. The
pockets are then filled with an aqueous or other composition and a
second film brought into position over the plurality of pockets.
The second film may be the same as the first film or another
material and is heat, or otherwise sealed, to the parts of the
first film remaining on the upper surface 18 of the mould, as
described previously.
[0052] The filled containers may then be separated from each other.
Alternatively, they may be left conjoined and, for example,
perforations provided between the individual containers so that
they can be separated easily at a later stage, for example by a
consumer. If the containers are separated, the flanges may be left
in place. However, desirably the flanges are reduced in order to
provide an even more attractive, three-dimensional appearance.
Generally the flanges remaining should be as small as possible for
aesthetic purposes while bearing in mind that some flange is
required to ensure the two films remain adhered to each other. A
flange having a width of 1 mm to 10 mm is desirable, preferably 1.5
mm to 6 mm, most preferably about 5 mm.
[0053] For containers of compositions having a high water content,
the containers may then be left for a while to attain their
attractive appearance, or may be immediately packaged into boxes
for retail sale, and left to attain their attractive appearance in
the boxes. The containers may themselves be packaged in outer
containers if desired, for example non-water soluble containers
which are removed before the water-soluble containers are used.
[0054] If more than one film is used for the containers, the films
may be identical or different. The film may be partially or fully
alcoholised or hydrolysed, for example, it may be from 40 to 100%,
preferably 70 to 92%, more preferably about 88% or about 92%,
alcoholised or hydrolysed, polyvinyl acetate film. The degree of
hydrolysis is known to influence the temperature at which the PVOH
starts to dissolve in water. 88% hydrolysis corresponds to a film
soluble in cold (i.e. room temperature) water, whereas 92%
hydrolysis corresponds to a film soluble in warm water. An example
of a preferred PVOH is ethoxylated PVOH. The film may be cast,
blown or extruded. It may also be unorientated, mono-axially
oriented or bi-axially oriented.
[0055] It is possible for suitable additives such as plasticisers,
lubricants and colouring agents to be added to the film. Components
which modify the properties of the polymer may also be added.
Plasticisers are generally used in an amount of up to 20 wt %, for
example, from 15 to 20 wt %. Lubricants are generally used in an
amount of 0.5 to 5 wt %. The polymer is therefore generally used in
an amount of from 75 to 84.5 wt %, based on the total number of the
composition used to form the film. Suitable plasticisers are, for
example, pentaerythritols such as depentaerythritol, sorbitol,
mannitol, glycerine and glycols such as glycerol, ethylene glycol
and polyethylene glycol. Solids such as talc, stearic acid,
magnesium stearate, silicon dioxide, zince stearate or colloidal
silica may also be used.
[0056] It is also possible to include one or more particulate
solids in the films in order to accelerate the rate of dissolution
of the container. This solid may also be present in the contents of
the container. Dissolution of the solid in water is sufficient to
cause an acceleration in the break-up of the container,
particularly if a gas is generated, when the physical agitation
caused may, for example, result in the virtually immediate release
of the contents from the container. Examples of such solids are
alkali or alkaline earth metal, such as sodium, potassium,
magnesium or calcium, bicarbonate or carbonate, in conjunction with
an acid. Suitable acids are, for example, acidic substances having
carboxylic or sulfonic acid groups or salts thereof. Examples are
cinnamic, tartaric, mandelic, fumaric, maleic, malic, palmoic,
citric and naphthalene disulfonic acids.
[0057] The film is generally cold water (20.degree. C.) soluble,
but, depending on its degree of hydrolysis, may be insoluble in
cold water at 20.degree. C. and only become soluble in warm water
or hot water having a temperature of, for example, 30.degree. C.,
40.degree. C., 50.degree. C. or even 60.degree. C. If the film is
soluble in cold water, or water at a temperature of up to say
35.degree. C., steps must be taken to ensure that an aqueous
composition contained inside the container does not dissolve the
film from the inside. Steps may be taken to treat the inside
surface of the film, for example by coating it with a
semi-permeable or partial water barrier such as polyethylene or
polypropylene or a hydrogel such as a polyacrylate. This coating
will simply fall apart or dissolve or disperse into microscopic
particles when the container is dissolved in water. Steps may also
be taken to adapt the composition to ensure that it does not
dissolve the film. For example, it has been found that ensuring the
composition has a high ionic strength or contains an agent which
minimises water loss through the walls of the container will
prevent the composition from dissolving the PVOH film from the
inside. This is described in more detail in EP-A-518,689 and WO
97/27743.
[0058] It is particularly important to avoid pinholes in the film
through which leakage of the contained composition may occur. It
may therefore be appropriate to use a laminate of two or more
layers of a different or the same film, as pinholes are unlikely to
coincide in two layers of material.
[0059] When first and second films are used to form the containers
of the present invention, the first film will generally have a
thickness before thermoforming of 20 to 500 .mu.m, especially 70 to
400 .mu.m, for example 70 to 300 .mu.m or 90 or 110 to 150 .mu.m.
The thickness of the second PVOH film may be less than that of the
first film as the second film will not generally be thermoformed so
localised thinning of the sheet will not occur. The thickness of
the second film will generally be from 20 to 150 .mu.m or 160
.mu.m, preferably from 40 or 50 to 90 or 100 .mu.m, more preferably
from 50 to 80 .mu.m.
[0060] The films may be chosen, if desired, such that they have the
same thickness before the first film is thermoformed, or have the
same thickness after the first sheet has been thermoformed in order
to provide a composition which is encapsulated by a substantially
constant thickness of film.
[0061] The containers of the present invention generally contain
from 5 to 100 g of aqueous composition, especially from 15 to 40 g,
depending on their intended use. For example, a dishwashing
composition may weigh from 15 g to 20 g, a water-softening
composition may weigh from 25 to 35 g, and a laundry composition
may weigh from 10 to 40 g, especially 20 to 30 g or 30 to 40 g.
[0062] The containers may have any shape achievable by
thermoforming. For example they can take the form of a cylinder,
cube or cuboid, i.e. a rectangular parallelepiped whose faces are
not all equal. In general, because the containers are not rigid,
the sides are not planar, but rather are convex. If the container
is formed from a thermoformed film and a planar film, the seam
between the two films will appear nearer one face of the container
rather than the other. Apart from the deformation of the container
due to the shrinkage of the film discussed above, deformation may
also occur at the stage of manufacture if desired. For example, if
the pocket is filled with a gelled composition having a height
greater than that of the pocket, the second film will be deformed
when placed on top of the pocket. A shaped sealing platen is
required to achieve this effect.
[0063] In general the maximum dimension of the filled part of the
container (excluding any flanges) is 5 cm. For example, a rounded
cuboid container may have a length of 1 to 5 cm, especially 3.5 to
4.5 cm, a width of 1.5 to 3.5 cm, especially 2 to 3 cm, and a
height of 1 to 2.5 cm, especially 1 to 2 cm, and more especially
1.25 to 1.75 cm.
[0064] The container desirably contains an aqueous composition
which is a fabric care, surface care or dishwashing composition.
Thus, for example, it may be a dishwashing, water-softening,
laundry or detergent composition or a rinse aid. In this case the
container is preferably suitable for use in a domestic washing
machine such as a laundry washing machine or a dishwashing machine.
The composition may also be a disinfectant, antibacterial or
antiseptic composition intended to be diluted with water before
use, or a concentrated refill composition, for example a
trigger-type spray as used in domestic situations. Such a
composition can simply be added to water already held in the spray
container. Examples of surface care compositions are those used to
clean, treat or polish a surface. Suitable surfaces are, for
example, household surfaces such as worktops, as well as surfaces
of sanitary ware, such as sinks, basins and lavatories.
[0065] The composition preferably contains greater than 3 wt % free
water based on the weight of the aqueous composition, in order to
ensure that the container has an attractive appearance. The actual
amount of water present in the composition may be in excess of the
amount of free water, since the total water content includes water
of solvation and water held within a gelled matrix. Free water can
be determined by a standard loss-on-drying determination test
carried out at 60.degree. C. for 3 hours at 200 mbar (20 kPa).
Desirably the composition contains more than 10 wt %, 15 wt %, 20
wt %, 25 wt % or 30 wt % total water, but desirably less than 80 wt
% total water, more desirably less than 70 wt %, 60 wt %, 50 wt %
or 40 wt % total water. It may, for example, contain from 30 to 65
wt % total water.
[0066] The remaining ingredients of the composition depend on the
use of the composition. Thus, for example, the compositions may
contain surface active agents such as an anionic, nonionic,
cationic, amphoteric or zwitterionic surface active agents or
mixtures thereof.
[0067] Examples of anionic surfactants are straight-chained or
branched alkyl sulfates and alkyl polyalkoxylated sulfates, also
known as alkyl ether sulfates. Such surfactants may be produced by
the sulfation of higher C.sub.8-C.sub.20 fatty alcohols.
[0068] Examples of primary alkyl sulfate surfactants are those of
formula:
ROSO.sub.3.sup.-M.sup.+
wherein R is a linear C.sub.8-C.sub.20 hydrocarbyl group and M is a
water-solubilising cation. Preferably R is C.sub.10-C.sub.16 alkyl,
for example C.sub.12-C.sub.14, and M is alkali metal such as
lithium, sodium or potassium.
[0069] Examples of secondary alkyl sulfate surfactants are those
which have the sulfate moiety on a "backbone" of the molecule, for
example those of formula:
CH.sub.2(CH.sub.2).sub.n(CHOSO.sub.3.sup.-M.sup.+)(CH.sub.2).sub.mCH.sub-
.3
wherein m and n are independently 2 or more, the sum of m+n
typically being 6 to 20, for example 9 to 15, and M is a
water-solubilising cation such as lithium, sodium or potassium.
[0070] Especially preferred secondary alkyl sulfates are the (2,3)
alkyl sulfate surfactants of formulae:
CH.sub.2(CH.sub.2).sub.x(CHOSO.sub.3.sup.-M.sup.+)CH.sub.3 and
CH.sub.3(CH.sub.2).sub.x(CHOSO.sub.3.sup.-M.sup.+)CH.sub.2CH.sub.3
for the 2-sulfate and 3-sulfate, respectively. In these formulae x
is at least 4, for example 6 to 20, preferably 10 to 16. M is a
cation, such as an alkali metal, for example lithium, sodium or
potassium. Examples of alkoxylated alkyl sulfates are ethoxylated
alkyl sulfates of the formula:
RO(C.sub.2H.sub.4O).sub.nSO.sub.3.sup.-M.sup.+
wherein R is a C.sub.8-C.sub.20 alkyl group, preferably
C.sub.10-C.sub.18 such as a C.sub.12-C.sub.16, n is at least 1, for
example from 1 to 20, preferably 1 to 15, especially 1 to 6, and M
is a salt-forming cation such as lithium, sodium, potassium,
ammonium, alkylammonium or alkanolammonium. These compounds can
provide especially desirable fabric cleaning performance benefits
when used in combination with alkyl sulfates.
[0071] The alkyl sulfates and alkyl ether sulfates will generally
be used in the form of mixtures comprising varying alkyl chain
lengths and, if present, varying degrees of alkoxylation.
[0072] Other anionic surfactants which may be employed are salts of
fatty acids, for example C.sub.8-C.sub.18 fatty acids, especially
the sodium, potassium or alkanolamine salts, and alkyl, for example
C.sub.8-C.sub.18, benzene sulfonates.
[0073] Examples of nonionic surfactants are fatty acid alkoxylates,
such as fatty acid ethoxylates, especially those of formula:
R(C.sub.2H.sub.4O).sub.nOH
wherein R is a straight or branched C.sub.8-C.sub.16 alkyl group,
preferably a C.sub.9-C.sub.15, for example C.sub.10-C.sub.14 or
C.sub.12-C.sub.14, alkyl group and n is at least 1, for example
from 1 to 16, preferably 2 to 12, more preferably 3 to 10.
[0074] The alkoxylated fatty alcohol nonionic surfactant will
frequently have a hydrophilic-lipophilic balance (HLB) which ranges
from 3 to 17, more preferably from 6 to 15, most preferably from 10
to 15.
[0075] Examples of fatty alcohol ethoxylates are those made from
alcohols of 12 to 15 carbon atoms and which contain about 7 moles
of ethylene oxide. Such materials are commercially marketed under
the trademarks Neodol 25-7 and Neodol 23-6.5 by Shell Chemical
Company. Other useful Neodols include Neodol 1-5, an ethoxylated
fatty alcohol averaging 11 carbon atoms in its alkyl chain with
about 5 moles of ethylene oxide; Neodol 23-9, an ethoxylated
primary C.sub.12-C.sub.13 alcohol having about 9 moles of ethylene
oxide; and Neodol 91-10, an ethoxylated C.sub.9-C.sub.11 primary
alcohol having about 10 moles of ethylene oxide.
[0076] Alcohol ethoxylates of this type have also been marketed by
Shell Chemical Company under the Dobanol trademark. Dobanol 91-5 is
an ethoxylated C.sub.9-C.sub.11 fatty alcohol with an average of 5
moles ethylene oxide and Dobanol 25-7 is an ethoxylated
C.sub.12-C.sub.15 fatty alcohol with an average of 7 moles of
ethylene oxide per mole of fatty alcohol.
[0077] Other examples of suitable ethoxylated alcohol nonionic
surfactants include Tergitol 15-S-7 and Tergitol 15-S-9, both of
which are linear secondary alcohol ethoxylates available from Union
Carbide Corporation. Tergitol 15-S-7 is a mixed ethoxylated product
of a C.sub.11-C.sub.15 linear secondary alkanol with 7 moles of
ethylene oxide and Tergitol 15-S-9 is the same but with 9 moles of
ethylene oxide.
[0078] Other suitable alcohol ethoxylated nonionic surfactants are
Neodol 45-11, which is a similar ethylene oxide condensation
products of a fatty alcohol having 14-15 carbon atoms and the
number of ethylene oxide groups per mole being about 11. Such
products are also available from Shell Chemical Company.
[0079] Further nonionic surfactants are, for example,
C.sub.10-C.sub.18 alkyl polyglycosides, such as C.sub.12-C.sub.16
alkyl polyglycosides, especially the polyglucosides. These are
especially useful when high foaming compositions are desired.
Further surfactants are polyhydroxy fatty acid amides, such as
C.sub.10-C.sub.18 N-(3-methoxypropyl)glycamides and ethylene
oxide-propylene oxide block polymers of the Pluronic type.
[0080] Examples of cationic surfactants are those of the quaternary
ammonium type. Examples of amphoteric surfactants are
C.sub.10-C.sub.18 amine oxides and the C.sub.12-C.sub.18 betaines
and sulfobetaines.
[0081] The total content of surfactants in the composition is
desirably 0.1 to 95 wt %, especially 60 or 75 to 90 wt %.
[0082] The total content of surfactants in the laundry or detergent
composition is desirably 60 to 95 wt %, especially 75 to 90 wt %.
Desirably, especially in a laundry composition, an anionic
surfactant is present in an amount of 50 to 75 wt %, a nonionic
surfactant is present in an amount of 5 to 20 wt %, and/or a
cationic surfactant is present in an amount of from 0 to 10 wt %
and/or a amphoteric surfactant may be present in an amount of from
0 to 10 wt %. Desirably, in a dishwashing composition, the anionic
surfactant is present in an amount of from 0.1 to 50 wt %, a
non-ionic surfactant is present in an amount of 0.5 to 20 wt %
and/or a cationic surfactant is present in an amount of from 1 to
15 wt %. These amounts are based
[0083] On the solids content of the composition, i.e. excluding any
water or solvent which may be present.
[0084] The compositions, particularly when used as laundry washing
or dishwashing compositions, may also comprise enzymes, such as
protease, lipase, amylase, cellulase and peroxidase enzymes. Such
enzymes are commercially available and sold, for example, under the
registered trade marks Esperese, Alcalase, Savinase, Termamyl,
Lipolase and Celluzyme by Nova Industries A/S and Maxatasc by
International Biosynthetics, Inc. Desirably the enzymes are present
in the composition in an amount of from 0.5 to 3 wt %, especially 1
to 2 wt %.
[0085] Dishwasher compositions usually comprise a detergency
builder. Suitable builders are alkali metal or ammonium phosphates,
polyphosphates, phosphonates, polyphosphonates, carbonates,
bicarbonates borates, polyhydroxysulfonates, polyacetates,
carboxylates and polycarboxylates such as citrates. The builder is
desirably present in an amount of up to 90 wt %, preferably 15 to
90 wt %, more preferably 15 to 75 wt %, relative to the total
content of the composition.
[0086] Further details of suitable components are given in, for
example, EP-A-694,059, EP-A-518720 and WO 99/06522.
[0087] The compositions may, if desired, comprise a thickening
agent or gelling agent. Suitable thickeners are polyacrylate
polymers such as those sold under the trade mark CARBOPOL, or the
trade mark ACUSOL by Rohm and Haas Company. Other suitable
thickeners are xanthan gums. The thickener, if present, is
generally present in an amount of from 0.2 to 4 wt %, especially
0.5 to 2 wt %.
[0088] The compositions can also optionally comprise one or more
additional ingredients. These include conventional detergent
composition components such as further surfactants, bleaches,
bleach enhancing agents, builders, suds boosters or suds
suppressors, anti-tarnish and anti-corrosion agents, organic
solvents, co-solvents, phase stabilisers, emulsifying agents,
preservatives, soil suspending agents, soil release agents,
germicides, phosphates such as sodium tripolyphosphate or potassium
tripolyphosphate, pH adjusting agents or buffers, non-builder
alkalinity sources, chelating agents, clays such as smectite clays,
enzyme stabilizers, anti-limescale agents, colourants, dyes,
hydrotropes, dye transfer inhibiting agents, brighteners and
perfumes. If used, such optional ingredients will generally
constitute no more than 10 wt %, for example from 1 to 6 wt %, of
the total weight of the compositions.
[0089] The builders counteract the effects of calcium, or other
ion, water hardness encountered during laundering or bleaching use
of the compositions herein. Examples of such materials are citrate,
succinate, malonate, carboxymethyl succinate, carboxylate,
polycarboxylate and polyacetyl carboxylate salts, for example with
alkali metal or alkaline earth metal cations, or the corresponding
free acids. Specific examples are sodium, potassium and lithium
salts of oxydisuccinic acid, mellitic acid, benzene polycarboxylic
acids, C.sub.10-C.sub.22 fatty acids and citric acid. Other
examples are organic phosphonate type sequestering agents such as
those sold by Monsanto under the trade mark Dequest and alkyl
hydroxy phosphonates. Citrate salts and C.sub.12-C.sub.18 fatty
acid soaps are preferred.
[0090] Other suitable builders are polymers and copolymers known to
have builder properties. For example, such materials include
appropriate polyacrylic acid, polymaleic acid, and
polyacrylic/polymaleic and copolymers and their salts, such as
those sold by BASF under the trade mark Sokalan.
[0091] The builders generally constitute from 0 to 3 wt %, more
preferably from 0.1 to 1 wt %, by weight of the compositions.
[0092] Compositions which comprise an enzyme may optionally contain
materials which maintain the stability of the enzyme. Such enzyme
stabilizers include, for example, polyols such as propylene glycol,
boric acid and borax. Combinations of these enzyme stabilizers may
also be employed. If utilized, the enzyme stabilizers generally
constitute from 0.1 to 1 wt % of the compositions.
[0093] The compositions may optionally comprise materials which
serve as phase stabilizers and/or co-solvents. Example are
C.sub.1-C.sub.3 alcohols or diols such as methanol, ethanol,
propanol and 1,2-propanediol. C.sub.1-C.sub.3 alkanolamines such as
mono-, di- and triethanolamines and monoisopropanolamine can also
be used, by themselves or in combination with the alcohols. The
phase stabilizers and/or co-solvents can, for example, constitute 0
to 1 wt %, preferably 0.1 to 0.5 wt %, of the composition.
[0094] The compositions may optionally comprise components which
adjust or maintain the pH of the compositions at optimum levels.
Examples of pH adjusting agents are NaOH and citric acid. The pH
may be from, for example, 1 to 13, such as 8 to 11 depending on the
nature of the composition. For example, a dishwashing composition
desirably has a pH of 8 to 11, a laundry composition has a pH of 7
to 9, and a water-softening composition has a pH of 7 to 9.
* * * * *