Note: Descriptions are shown in the official language in which they were submitted.
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DISPOSABLE, MOISTURE VAPOUR PERMEABLE, LIQUID IMPERMEABLE
COVERING SHEET CONTAINING ACTIVE AGENTS
Field of the Invention
The present invention relates to a disposable covering sheet preferably for
bedding items such as mattresses, pillows, etc. which is moisture vapour
permeable, liquid impermeable, and has active agents releasing properties. The
covering sheet comprises liquid impermeable formed structures having a
moisture vapour permeability comprising thermoplastic compositions preferably
applied onto a moisture vapour permeable substrate. The covering sheet of the
present invention can find a variety of applications wherein moisture vapour
permeability, liquid imperviousness, disposability, comfort, specific active
agents
releasing properties are desirable. Preferably the covering sheet of the
instant
invention is a mattress cover or a pillow cover.
Background of the Invention
Covering sheets, particularly covering sheets for bedding articles, such as
bed mattress covers, are known in the art. A primary use of these articles is
to
protect mattresses, particularly bed mattresses, but also pillows, cushions,
duvets, upholstery, from contaminants, e.g. from dust, liquids, or bodily
fluids, for
example in environments where a mattress is intended to be used by different
users, such as in hospitals, hotels, or rental houses. Furthermore, mattress
covers are used in house for providing a mattress with a protective covering.
More recently mattress covers have been also proposed to act as an
allergen barrier to control house mites that live in the dust, typically on
and within
mattresses where they can find favourable environmental conditions in terms of
temperature and nourishment.
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It has long been established that house mites, also known as dust mites,
are a source of house dust allergens that not only cause allergies, but also
adversely contribute to other pathologies, such as asthma. It has also been
established that use of allergen control measures is effective in controlling
these
conditions. Allergen-proof encasing to contain mites to prevent allergen
egress
has long been used in mattresses, such as bed mattresses, pillows, cushions,
duvets, upholstery.
Mattress covers come in direct or indirect (i.e. through further intermediate
layers, e.g. bed sheets, or pillowcases) contact with the human body,
therefore it
is important that such covers are moisture vapour permeable for comfort
reasons, in addition to being liquid impermeable in order to provide the
mattress
with the desired protection against external agents. When used as a barrier
against dust mites they should also have an allergen barrier capability.
Various examples of disposable mattress covers which are at the same
time liquid impermeable and breathable, i.e. moisture vapour permeable, are
known in the art.
Known disposable mattress covers comprise different materials or
structures which are capable of providing a liquid barrier, in addition to
providing
moisture vapour permeability, preferably air permeability. Such structures or
materials can comprise a single layer, or multiple layers laminated together.
An
example are structures comprising thermoplastic microporous films, e.g.
laminated to fibrous layers such as nonwoven layers.
Particularly preferred materials which are suitable for disposable mattress
covers are hydrophilic continuous films, also known as "monolithic films",
that do
not allow the flow of moisture vapour through open pores or apertures in the
material, but do transfer substantial amounts of moisture vapour through the
film
by absorbing water on one side of the film where the moisture vapour
concentration is higher, and desorbing or evaporating it on the opposite side
of
the film where the moisture vapour concentration is lower.
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In our patent applications EP 0963760 and. EP 0964026 thermoplastic
compositions are disclosed for making hydrophilic continuous moisture vapour
permeable, liquid impermeable layers having preferred characteristics of
moisture vapour permeability and liquid imperviousness. The disclosed
preferred
thermoplastic compositions are also readily processable so as to provide a
coating having the desired thickness onto a substrate, so avoiding the need of
complex traditional extrusion apparatuses. This is achieved by modifying the
viscosity of the thermoplastic polymers by means of the inclusion in the
composition of a suitable plasticiser or blend of plasticisers that lowers
such
viscosity. This allows to utilise with these preferred compositions typical
process
conditions known in the art for the direct coating of low viscosity hot melt
compositions onto a substrate in order to form a moisture vapour permeable,
liquid impervious film or layer.
Disposable, moisture vapour permeable, liquid impermeable mattress
covers comprising a moisture vapour permeable, liquid impermeable structure,
which in turn comprises a layer of the thermoplastic compositions according to
either EP 0963760 or EP 0964026, preferably applied onto a moisture vapour
permeable substrate, e.g. a fibrous layer such as a nonwoven layer in order to
form a composite structure, are particularly preferred since they provide
better
moisture vapour permeability combined with liquid imperviousness, and also
take
advantage of the increased ease of manufacture associated to the above
mentioned compositions.
Another improvement to disposable mattress covers is described in our
European patent application No. 99124535.8, filed on 9 December 1999, where
an increased friction is established between the disposable mattress cover and
the mattress surface during the use, when i.e. the mattress cover is typically
subjected to a certain compression against the mattress itself, in order to
minimise possible misplacements of the cover during its use, for example when
the mattress is a bed mattress or a pillow, and the mattress cover can be
moved
or misplaced by the user's movement, e.g. during the sleep. This is
particularly
important when the mattress cover is intended for partial covering of the
external
surface of a mattress, for example of the upper surface of a bed mattress,
e.g., in
combination with traditional means for connecting the cover to the mattress,
such
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as for example elastic bands or strands applied at the corners of a
rectangular
bed mattress cover.
Provision of an increased friction between the mattress cover and the
mattress is however also useful in' the context of a mattress cover intended
for
total encasing of a mattress. In both cases in fact this increased friction
prevents
or at least reduces relative movements between the mattress cover and the
mattress during the use, therefore helping in keeping the mattress cover in
its
right position provided initially, e.g. by the user when applying the cover to
the
mattress.
Even if the covering sheets disclosed in our above mentioned patent
applications function well, particularly in terms of protection, they can be
improved in terms of further benefits for the user by adding active agents
releasing properties to them. While systems for'releasing active agents such
as
perfumes, volatile therapeutic materials, etc. are known in the art and also
in the
field of covering sheet for bedding articles, see for example WO 99/17643, it
is
not known a disposable covering sheet particularly for bedding items such as
mattresses, pillows, etc. which is moisture vapour permeable, liquid
impermeable
and has specific active agents releasing properties.
Summar~of the Invention
A disposable, moisture vapour permeable, liquid impermeable, covering
sheet comprising at least a moisture vapour permeable layer and a liquid
impermeable but moisture vapour permeable film layer preferably applied onto
said moisture vapour permeable layer, the covering sheet has specific active
agent releasing properties.
In particular, said covering sheet comprises an active agent releasing system
which is able to provide a long lasting release of active agents and, more
specifically, an active agent odour intensity positive difference of at least
5,
preferably of at least 10, more preferably of at least 15, after 7 and
preferably
after 14 days compared to the active agent odour intensity of the active agent
itself after the same periods of time, the value determined according to the
Active
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Agent Intensity Test described herein, in order to provide a prolonged release
of
the active agent after the initial use of the covering sheet.
Brief Description of the Drawings
The drawings herein are intended to illustrate preferred embodiments of the
present invention, but are not meant to limit in any way its scope.
Figure 1 is a schematic plan view of a disposable mattress cover according
to the present invention.
Figure 2 is a cross-sectional view of the disposable mattress cover of figure
1 taken along the line A-A.
Figure 3 illustrates the mattress cover applied to a mattress.
Detailed Description of the Invention
According to the present invention, a disposable, moisture vapour
permeable, liquid impermeable covering sheet is provided which comprises at
least a moisture vapour permeable layer and a liquid impermeable but moisture
vapour permeable film layer comprising a highly processable thermoplastic
composition having moisture vapour permeability. Said covering sheet offers a
further benefit to the user, particularly when used as a covering sheet for
bedding articles such as a mattress cover, by providing active agents
releasing
properties.
Covering sheets according to the present invention can be used to cover
and protect different articles in a variety of fields for both domestic,
industrial or
institutional usage; such usages include, but are not limited to, covering
sheets
for headrests and seats, both for domestic use or institutional use, and for
use in
the transportation industry, table covers of dining sets, covering sheets for
medical examination tables, covering sheets for furniture, etc.
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The preferred utilization of the covering sheets herein is in bedding
articles,
both for domestic and institutional usage. The coveririg sheets of the present
invention are particularly useful for use in disposable bed mattress covers
and
pillow cases or covers.
The term "mattress", as used therein, refers to a fabric case filled with
resilient material, such as for example cotton, hair, feathers, foam rubber,
or an
arrangement of coil springs, and therefore comprises particularly bed
mattresses,
but also pillows, cushions, comforters, duvets, upholstered portions of beds
(such
as headboards), or of sofas or armchairs. Consequently, even if the present
invention will be described with particular reference to a disposable covering
sheet for bedding items in the form of a mattress cover, it is not meant to
limit in
any way its scope to mattress covers.
Referring particularly to mattresses it is generally known that each mattress
every year "absorbs" from about 45 kilos to about 80 kilos of sweat and about
150 grams of skin scales. In addition to this, millions of mites generally
live in the
mattress. Another problem is that accidental staining is practically
unavoidable.
Usually consumers are aware of the above problems and, in fact, most of them
use reusable mattress covers which usually are made from cotton. But these
covers do not solve the above problems and, in particular, they are not
capable
of providing an effective action of releasing active agents which means to be
able to emit active agents, particularly perfumes, volatile therapeutic
materials,
etc., in a controlled manner with a long lasting release of said active
agents.
The disposable covering sheet of the present invention consists in a
laminate of different layers comprising at least a first moisture vapour
permeable
layer and a second liquid impermeable but moisture vapour permeable film layer
of thermoplastic composition bonded onto said first layer, i.e. the laminate
preferably consists of at least two bonded layers giving rise to a composite
structure.
If more film layers of thermoplastic compositions are utilised in a composite
structure in combination with one or more other moisture vapour permeable
layers to create a layered moisture vapour permeable, liquid impermeable
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composite structure, each film layer can be made of a same specific
thermoplastic composition or of different specific thermoplastic compositions.
The above composite structure can involve at least one component,
typically the film layer, of the thermoplastic composition in combination with
one
or more other moisture vapour permeable layers. Such moisture vapour
permeable materials include, but are not limited to: fibres, fibrous batts,
non
wovens, wovens, papers, micro-porous or porous membranes, films such as
polymeric films, perforated or apertured films and papers, macroscopically
expanded films, cloth, etc.
Said other components may be non-absorbent, absorbent,. liquid-
containing, etc.
The composite structures of the covering sheets described above have a
moisture vapour transfer rate (WVTR) of at least 400 g/m2.24h, more preferably
at least 500 g/m2.24h, and most preferably at least 600 g/m2.24h, but they are
impermeable to liquids.
According to a particularly preferred embodiment of the present invention
the disposable, moisture vapour permeable, liquid impermeable mattress cover
comprises a composite structure comprising a film layer of the thermoplastic
composition applied onto a moisture vapour permeable substrate, wherein said
film layer is intended, in use, to directly contact the mattress. The moisture
vapour permeable substrate preferably comprises a fibrous layer, e.g. a
nonwoven layer onto which the thermoplastic composition is applied in a
continuous layer or film by means of known means, e.g. preferably by hot melt
coating.
A disposable, moisture vapour permeable, liquid impermeable mattress
cover comprising a moisture vapour permeable, liquid impermeable structure in
turn comprising a layer of the thermoplastic composition which is intended, in
use, to directly contact a mattress, can have any shape and arrangement which
is known in the art, and which is suitable for its intended use.
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For example, if the mattress consists of a standard bed mattress, the
mattress cover can be a substantially rectangular flat sheet with elastic
strings at
the corners, or alternatively with integrally elasticised corners, as
described in
FR 2747899. The rectangular sheet typically has suitable dimensions in order
to
completely cover at least the upper surface of the bed mattress, and
preferably,
as in the latter embodiment referred to above, also the side surfaces thereof,
wherein the elastic strings or the elasticised corners provide for a suitable
releasable connection, in a way known in the art, to the mattress. Alternative
configurations where the mattress cover has a suitable shape and size in order
to
completely encase a mattress are also possible. This latter configuration
could
be preferred when the mattress cover, in addition to liquid imperviousness and
moisture vapour permeability, should also provide a total barrier against dust
mites and related allergens.
Preferably, as shown in the herein drawings, a disposable mattress cover
comprises a rectangular blanket made according to the present invention. In
particular, the disposable, moisture vapour permeable, liquid impermeable
blanket is formed by a topsheet 1, which is preferably a moisture vapour
permeable fibrous layer, and a backsheet 2, which is a liquid impermeable but
moisture vapour permeable film layer of a thermoplastic composition laminated
onto said topsheet 1 in order to form a two-layer composite structure. The
backsheet 2 is intended to face and to be in direct contact with the top of a
mattress 4, while the topsheet 1 is intended to face the user.
The thermoplastic compositions can provide a certain degree of residual
tackiness to the backsheet 2. In turn, this tackiness prevents or at least
reduces
relative movements between the mattress cover and the mattress 4 during use,
therefore helping in keeping the mattress cover in its right position provided
by
the user initially. In any case and if preferred, the mattress cover can have
no
residual tackiness by suitably selecting the thermoplastic compositions or by
neutralising any residual tackiness with known means, e.g. talcum powder. This
tackiness can be also useful for incorporating the active agents in the
mattress
cover according to the present invention.
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For assisting the user to put the mattress cover on the mattress in the right
position but also for fixing the mattress cover to the mattress in a stable
manner
adhesive means 3 are provided, as shown in the drawings. The adhesive means
3 can be one or more stripes of a conventional pressure sensitive adhesive
covered by a release liner for protecting the adhesive before use, as
utilised, for
example, in the manufacture of the panty fastening adhesive patch of
commercial sanitary napkins, or pieces of double sided adhesive tapes, etc.
As shown in figure 3, the mattress cover has suitable dimensions to
completely cover at least the top surface and partially the longitudinal sides
6 of
the mattress 4, while the adhesive means 3 are preferably attached to the
longitudinal sides 6 of the mattress 4. .
Any other suitable shape or arrangement for a mattress cover according to
the present invention is also possible, depending on the particular mattress
type,
shape and dimensions, and on the intended use of the mattress cover.
Preferably the disposable, moisture vapour permeable, liquid impermeable
covering sheet of the present invention, when used as a mattress cover or a
pillow cover, has a surface area ranging from 15.0 m2 to 0.3 m2, preferably
from
8.0 m2 to 0.5 m2. Most preferably, particularly in the case of a mattress
cover,
said surface area is from 5.0 m2 to 1.0 m2.
Suitable thermoplastic compositions for the backsheet 2 can be those
disclosed in the European patent applications EP 963760 and EP 964026,
already mentioned in the background of the invention, but other compositions
which form monolithic breathable films can be utilised.
Residual tackiness of the thermoplastic composition can be advantageously
provided by the selection of the tackifying resin; indeed the thermoplastic
compositions described in the above applications typically include resins or
blends of tackifying resins. Preferred resins, which may be present by up to
50%
by weight of the thermoplastic composition, may be selected from rosins and
rosin esters, hydrocarbon resins, aliphatic resins, terpene and terpene-
phenolic
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resins, aromatic resins, synthetic C5 resins, mixtures of synthetic C5-C9
resins,
and mixtures thereof.
By suitably selecting the tackifier resin or blend of tackifier resins, it is
possible to adjust the residual tackiness at room temperature of the
thermoplastic composition, and therefore of the layer formed from said
thermoplastic composition, to the extent that it has the typical
characteristics of a
pressure sensitive adhesive.
Preferred tackifier resins, or blend of tackifier resins still have a
softening
point of 125°C or less, and are selected from the group consisting of
rosin and
rosin esters, terpene-Phenolic resins, aromatic resins, and mixtures thereof.
More preferably, the thermoplastic compositions according to the above
mentioned applications comprise a blend of tackifier resins, selected as
described above, wherein moreover from 0% to 20%, preferably from 2% to 15%,
by weight of said blend of tackifier resins comprises a resin or blend of
resins
having a softening point of less than 25°C, and from 80% to 100%,
preferably
from 85% to 98%, by weight of said blend of tackifier resins comprises a resin
or
blend of resins having a softening point of at least 70°C.
Other thermoplastic compositions for the backsheet 2 are those described
in our European patent application No. 00116284.1, filed on 10 August 2000
with
title: "Thermoplastic hydrophilic polymeric compositions with improved
adhesive
properties for moisture vapour permeable structures" (P&G Case CM2406F).
Monolithic films are preferred materials because they do not allow the flow
of moisture vapour through open pores or apertures in the material, but do
transfer substantial amounts of moisture vapour through the film by absorbing
water on one side of the film where the moisture vapour concentration is
higher,
and desorbing or evaporating it on the opposite side of the film where the
moisture vapour concentration is lower. Consequently, while they allow the
passage of moisture vapour, they are truly impermeable to liquids, dust, etc..
Active anent releasing system
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According to the present invention the disposable covering sheet
comprises as an essential component an active agent releasing system which is
able to release one or more active agents in a controlled manner.
Active materials such as, for example, perfume, which will release a
fragrance during their utilisation, can be utilised.
As used herein the term perfume means any odoriferous material. In general,
such materials are characterised by a vapour pressure less than atmospheric
pressure at ambient temperatures. The perfume employed herein will most often
be liquid at ambient temperatures, but also can be solids such as the various
camphoraceous perfumes known in the art. A wide variety of chemicals are
known
for perfumery uses, including materials such as aldehydes, ketones, esters and
the like. More commonly, naturally occurring plant and animal oils and
exudates
comprising complex mixtures of various chemical components are known for use
as perfumes, and such materials can be used herein. The perfumes herein can
be
relatively simple in their composition or can comprise highly sophisticated,
complex mixtures of natural and synthetic chemical components, all chosen to
provide any desired odour.
Typical perfumes herein can comprise, for example, woody/ earthy bases
containing exotic materials such as sandalwood oil, civet, patchouli oil and
the
like.
The perfumes herein can be of a light, floral fragrance, e.g., rose extract,
violet extract and the like. The perfumes herein can be formulated to provide
desirable fruity odours, e.g., lime, lemon, orange and the like.
Perfume materials are described more fully in S. Arctander, Perfume
Flavors and Chemicals. Vols. I and II. Aurthor, Montclair, N.J., and the Merck
Index, 8th Edition, Merck & Co., Inc. Rahway, N.J..
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In short, any chemically compatible material which exudes a pleasant or
otherwise desirable odour can be used in the perfumed particles herein to
provide a desirable odour when applied to articles according to the present
invention.
Perfumes which are normally solid can also be employed in the present
invention. These may be admixed with a liquefying agent such as a solvent
prior
to incorporation into the articles of the present invention by spraying, or
may be
simply melted and incorporated in the film layer, as long as the perfume does
not
sublime or decompose upon heating.
Preferably, starch encapsulated perfumes, as described for example in GB
1464616, can be utilised as the active agent releasing system in the covering
sheet according to the present invention. Encapsulation allows a long lasting
release of perfumes.
More preferably, useful active agent releasing systems can be selected
among those disclosed in WO 00102987, EP 0971021, EP 0971024, and EP
0971025 which describe, inter alias, a product of reaction between an amino
functional polymer comprising at least one primary and/or secondary amine
group and an active component selected from ketone, aldehyde, or mixture
thereof. Preferably, the active agent releasing system can be the product of
reaction between a primary amine and a ketone or aldehyde perfume
component. By utilising the product of reaction described by the above patent
applications, the release of the active agent (for example, a perfume
component) lasts for a longer period of time than by the use of the active
alone
itself.
It should be noted that active agents are not limited to perfumes but other
know active agents selected from insecticides, deodorants, volatile
therapeutic
materials, aromatic oils and mixtures thereof can be utilised for providing a
benefit to the user.
Volatile therapeutic materials include materials which assist in keeping nasal
passages clear of congestion in cold or allergy sufferers, for example
menthol,
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camphor, eucalyptus oil and similar oil, as well as other materials which can
benefit a patient by absorption through the nasal passages and the lungs as a
result of prolonged exposure. The therapeutic materials may include extracts
of
herbs and the like which help the user to relax or to sleep. Aromatic oils,
such as
those referred to as 'aromatherapy oils' may also be used into the substrate.
The active agent to be used in the active agent releasing system of the
present invention is preferably selected from any of the above agents or
combinations thereof.
The active agent or agents can be incorporated in the article of the present
invention by any of the methods disclosed in the art.
Other characteristics
A moisture vapour permeable, liquid impervious layer can be formed from a
suitable thermoplastic composition by coating said thermoplastic composition
onto a substrate.
A process for making a film layer from a thermoplastic composition
according to the present invention typically comprises the steps of providing
said
composition, heating it to make it flowable, and coating said composition in
the
molten state onto a substrate in a layer having the desired thickness. It
should be
noted that active agents can be included in the thermoplastic composition.
Alternatively, they can be applied onto the surface of the film or layer made
of the
thermoplastic composition, e.g. directly adhered thereto by taking advantage
of
the tackiness of the composition immediately or shortly after formation of the
layer or film as mentioned above. ,
In accordance with the present invention, a moisture vapour permeable,
water impervious composite is formed which comprises the thermoplastic
composition and a substrate onto which said thermoplastic composition is
coated, wherein the substrate is also moisture vapour permeable.
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Such embodiment provides a moisture vapour permeable, liquid impervious
composite structure wherein the film layer formed from the thermoplastic
composition is firmly bonded to the substrate while providing the required
performance for liquid barrier and hence could be advantageously provided as
thinly as possible. In this manner such embodiment provides a moisture vapour
permeable, liquid impervious composite structure wherein the contribution of
the
film layer formed from the thermoplastic composition to the performance of the
composite material resides mainly in the provision of a liquid barrier. The
remaining performance physical criterion being preferably provided by the
provided substrate, that therefore preferably acts also as a support layer.
However it should be noted that the film layer does not need to be as thin as
possible in any application because the thermoplastic compositions, according
to
our before mentioned patent applications, provide high breathability (high
WVTR)
also in the case of thicker film layers. Typical thickness of the film layer
of the
thermoplastic composition applied onto a suitable substrate to form a
composite
structure according to the present invention range from 2,~m to 200,~m.
The substrate, or support layer may be any useful layer which is also
moisture vapour permeable, preferably having a moisture vapour permeability of
at least 400 g/m2.24h, more preferably at least 500 g/m2.24h, and most
preferably at least 600 g/m2.24h.
Preferred support layers for use herein include woven and nonwoven
layers, most preferably hydrophobic fibrous layers such as hydrophobic
nonwoven. As for non limiting examples, a SMS (Spunbonded-Meltblown-
Spunbonded) hydrophobic 100% polypropylene nonwoven of 17 g/m2 or of 25
g/m2 both commercialised under the code G17A10, MD3000, respectively, by
Corovin - BBA Nonwovens Group (Germany), or a spunlaced nonwoven of 50
g/m2 commercialised under the code TJET C500 by Tecnofibra (Italy) function
well.
Suitable substrates for use herein as further layers in the structure
according to the present invention could also include two dimensional, planar
micro and macro-porous films; macroscopically expanded films; formed
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apertured films; nonwoven and woven layers. Suitable macroscopically expanded
films for use herein include films as described in for example in US 4,637,819
and US 4,591,523.
The structures of the preferred embodiment according to the present
invention are particularly advantageous as they allow the possibility of
providing a
composite wherein the thermoplastic composition may be applied onto the
support substrate as a film layer with the desired thickness. Typical coating
conditions and apparatuses known in the art for the direct coating of low
viscosities hot melts can be readily utilised in order to provide the
thermoplastic
composition at the desired thickness.
A possible method for forming a composite laminate by coating the
thermoplastic composition onto a substrate acting as a support layer is
described
in PCT application WO 96/25902.
At least at the coating temperature, the thermoplastic composition in form of
a layer preferably exhibits adhesive properties on the supportive substrate in
order to form the preferred composite such that no additional adhesive is
required to achieve a permanent attachment between the thermoplastic
composition and the substrate.
A moisture vapour permeable, liquid impervious composite structure formed
by coating a thermoplastic hydrophilic composition onto a suitable substrate
finds
particular utility as a structure constituting a disposable, moisture vapour
permeable, liquid impermeable mattress cover according to the present
invention.
Example
A polyether-amide block copolymer available from Atofina (France)
commercialised under the trade name Pebax 2533 SN is compounded with Tri
Butyl Citrate (plasticiser) available from Aldrich Co., Res A-2691 (tackifier
resin)
available from Hercules Inc., Res A-2690 (tackifier resin) available from
Hercules Inc., both resins described in our already mentioned European
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application No. 00116284.1, and Irganox 1010 (anti oxidant agent) available
from
Ciba-Geigy.
The final formulation in percent by weight has the following composition:
44% Pebax 2533
SN
25% Tri Butyl Citrate
15% Res A-2691
15% Res A-2690
1 % I rganox 1010
The blend is melt extruded to obtain a film having a basis weight of 20 g/m2.
The film is laminated directly onto a substrate constituted by a SMS
(Spunbonded-Meltblown-Spunbonded structure) hydrophobic 100%
polypropylene nonwoven 25 g/m2 (support layer) commercialised under the trade
name MD3000, available form Corovin - BBA Nonwovens Group (Germany). The
composite has a WVTR of 846 g/m2.24h.
The composite structure is used to produce a mattress cover, e.g. a bed
mattress cover as illustrated in the herein drawings. It has a flat
rectangular
shape with suitable dimensions to completely cover at least the upper surface
of
a bed mattress, wherein the film layer 2 of thermoplastic composition is
intended
to face, in use, the mattress 4, and to directly contact it. In particular,
the
dimension are: 1.75 m (width) and 2.10 m (length) to completely cover the
upper
surface of a bed mattress 4 and partially its longitudinal sides 6 as
indicated in
figure 3. The corners of the mattress cover are fixed to the corners of the
bed
mattress by_adhesive tapes 3, after detaching the release liners 5 which
protect
the adhesive surface of adhesive tapes before use. The adhesive tapes 3 are
pieces of double sided adhesive tape, each having a width of 50mm and a length
of 300 mm, available from Avery Dennison Co. under FT310 code.
It should be noted that other adhesive tapes could be provided along the
longitudinal edges of the mattress cover for better fixing it to the
longitudinal
sides 6 of a bed mattress 4.
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Different samples of the above material for mattress cover having 10 cm x
cm dimensions were sprayed with different amounts of a suspension in
ethanol of a "perfume" (the active agent releasing system) which is a product
of
reaction between an amino functional polymer and a ketone perfume such as
5 Delta-Damascone. In particular, the "perfume" is produced in accordance with
the teachings of WO 00/02987. It consists of 60% by weight of Delta-Damascone
and 40% by weight of Lupasol WF available from Basf AG (Germany). The
above "perfume" can be generally defined as an amine reaction product of a
compound containing a primary amine functional group and an active ketone or
10 aldehyde containing components. Such preferred compounds and other useful
active agents are described in WO 00/02987, EP 0971021, EP 0971024, and EP
0971025.
The Delta-Damascone perfume was selected because it is described by
trained perfumers as being fresh and having the odour of roses and apples, but
other fragrances, as it is known in the art and also in above references, can
be
utilised.
The "perfume" was applied onto the samples by spraying. In particular, the
"perfume" was first liquefied by suspending it in dimethicone (50% "perfume"
and
50% dimethicone), then this suspension is mixed at different levels with
ethanol
and sprayed onto the sample to obtain different amounts of Delta-Damascone
(i.e. the active agent ), as indicated in the following table which also
reports the
value of Odour Intensity (perfume intensity) assessed by expert panellists in
accordance with the Active Agent Intensity Test hereinafter described.
of "perfume" corresponding Odour Intensity Odour Intensity
in ethanol (by weight of Delta- after 7 days after 14 days
weight) Damascone/ m2
2.5 0.060 g 30 15
0.5 0.012 g 15 10
0.1 0.003 0 0
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The reference was the same sample above described which had a 0.02% of
Delta-Damascone suspension in ethanol sprayed onto it giving a basis weight of
0.012 g/m2 of Delta-Damascone. The reference had no detected intensity after 7
and 14 days according to the Active Agent Intensity Test.
As it is evident from the above table, a basis weight of 0.012 g/m2 of Delta-
Damascone applied on the samples in accordance with the present invention,
gives a level of odour intensity of 10 after 14 days, showing a corresponding
positive difference when compared to the reference which had no detected
intensity after the same period of time notwithstanding the fact that the
reference
had the same initial quantity of Delta-Damascone perfume sprayed on it as a
pure perfume, rather than combined in an active agent releasing system.
It should be noted that, as also indicated in the Active Agent Intensity Test
described below, a positive difference of Odour Intensity of 5 grades after 7
days and preferably after 14 days is consumer meaningful and a positive
difference of 10 grades after 7 days and preferably after 14 days is
substantial.
This means that the mattress cover according to the present invention, since
initially used and applied to the mattress by the consumer (i.e. since the
initial
use for its intended purpose), is able to release the active agent for a
period of
time of 7 days and preferably for a period of time of 14 days in a effective
manner.
By the term "initial use" it is meant herein the time when the covering is
taken out of its packaging and applied to the article, e.g. to the bed
mattress.
Tests.
Moisture vapour permeability is measured as Water Vapour Transmission
Rate (WVTR) at 23°C and 50% relative humidity according to the
modified ASTM
E-96 "Upright Cup" method. The only modification to the standard ASTM E-96
"Upright Cup" method consists in a change in the height of the air gap between
the sample and the water surface in the cup, which height is 3 mm ~ 0.5 mm,
instead of 19 mm ~ 2.5 mm, as specified in the standard test method.
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Active Aaent Intensity Test
adour intensity (i.e. perfume intensity in the case of an active agent such as
a perfume) is assessed by a panel of expert graders smelling carefully the
samples after 7 and 14 days from the sample preparation, which can be
considered to correspond to the initial use of the product in real use
situation.
Samples can be directly prepared as explained above, or taken from an existing
covering sheet. In the latter case, the samples are cut from a covering sheet
immediately after the covering sheet is taken out of its packaging. The
samples
have 10 cm x 10 cm dimensions. After preparation the samples are left to rest
at
room conditions for the desired time. A 0-100 scale is used for odour
gradings.
The grading scale is as follows:
100 = extremely strong
odour
75 = very strong odour
50 = strong odour
40 = moderate odour
30 = slight odour
= weak odour
.
10 = very weak odour
0 = no odour
A mean positive difference (i.e. a residual amount of odour intensity) of
more than 5 grades after 7 days and preferably after 14 days between the
active
20 agent releasing system according to the invention and the active raw
material
alone is consumer meaningful. A positive difference of 10 grades or more after
7
days and preferably after 14 days is substantial. ~In other words, when a
positive
difference of intensity grade of more than 5, preferably of at least 10, more
preferably of at least 15, is observed between an active releasing system and
the active raw material alone, after 7 days and preferably after 14 days, it
can be
concluded that the active agent releasing system is suitable for use in the
present invention because the release of the chosen active component is
longer,
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i.e. it acts for a longer period of time. In this manner an effective benefit
is
provided for the consumer.
