U.S. patent application number 10/165254 was filed with the patent office on 2002-10-17 for disposable, moisture vapour permeable, liquid impermeable mattress cover assembly having an improved structure.
This patent application is currently assigned to The Procter & Gamble Company. Invention is credited to Corzani, Italo, Russo, Elisabetta.
Application Number | 20020148047 10/165254 |
Document ID | / |
Family ID | 8239564 |
Filed Date | 2002-10-17 |
United States Patent
Application |
20020148047 |
Kind Code |
A1 |
Corzani, Italo ; et
al. |
October 17, 2002 |
Disposable, moisture vapour permeable, liquid impermeable mattress
cover assembly having an improved structure
Abstract
The present invention relates to a disposable mattress cover
assembly for the formation of a protective cover capable of
completely encasing a mattress. The disposable mattress cover
assembly comprises a first and a second layer that are combined
together by means of cooperating joining means in order to form the
protective mattress cover. The disposable mattress cover assembly
of the present invention can find a variety of applications wherein
moisture vapour permeability combined with liquid imperviousness
are desirable, combined with easy of use.
Inventors: |
Corzani, Italo; (Chieti,
IT) ; Russo, Elisabetta; (Roma, IT) |
Correspondence
Address: |
THE PROCTER & GAMBLE COMPANY
INTELLECTUAL PROPERTY DIVISION
WINTON HILL TECHNICAL CENTER - BOX 161
6110 CENTER HILL AVENUE
CINCINNATI
OH
45224
US
|
Assignee: |
The Procter & Gamble
Company
Cincinnati
OH
|
Family ID: |
8239564 |
Appl. No.: |
10/165254 |
Filed: |
June 7, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10165254 |
Jun 7, 2002 |
|
|
|
PCT/US00/33218 |
Dec 8, 2000 |
|
|
|
Current U.S.
Class: |
5/738 ; 5/487;
5/699; 5/737 |
Current CPC
Class: |
A47C 31/007 20130101;
A47C 27/006 20130101; A47C 31/105 20130101; A47G 2009/001 20130101;
A47G 9/0246 20130101 |
Class at
Publication: |
5/738 ; 5/737;
5/699; 5/487 |
International
Class: |
A47G 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 9, 1999 |
EP |
99124536.6 |
Claims
What is claimed is:
1. A disposable mattress cover assembly for completely encasing a
mattress, said assembly comprising: a. a first layer comprising an
outer periphery; and b. a second layer comprising an outer
periphery; wherein said first and second layers are separate prior
to use; further wherein said first and second layers comprise a
joining means; further wherein said first and second layers may be
joined via said joining means to completely encase a mattress; and
further wherein at least one of said first or second layers
comprises a moisture vapor permeable and liquid impermeable
material.
2. A disposable mattress cover assembly according to claim 1,
wherein the joining means of said first layer is situated along
said outer periphery.
3. A disposable mattress cover assembly according to claim 1,
wherein the joining means of said second layer is situated along
said outer periphery.
4. A disposable mattress cover assembly according to claim 1,
wherein said first layer comprises at least one material different
than that of said second layer.
5. A disposable mattress cover assembly according to claim 1,
wherein said first layer comprises a moisture vapor permeable and
liquid impermeable material.
6. A disposable mattress cover assembly according to claim 1,
wherein said second layer comprises a moisture vapor permeable and
liquid impermeable material.
7. A disposable mattress cover first layer for use in the
disposable mattress cover according to claim 1, said first layer
comprising a joining means for connection to the joining means of
said second layer; wherein said first layer comprises a moisture
vapor permeable and liquid impermeable material.
8. A disposable mattress cover first layer according to claim 7,
wherein said moisture vapor permeable and liquid impermeable
material comprises a water vapor transmission rate (WVTR) of at
least about 300 g/m.sup.2.multidot.24 h.
9. A disposable mattress cover second layer for use in the
disposable mattress cover according to claim 1, said second layer
comprising a joining means for connection to the joining means of
said first layer; wherein said second layer comprises a moisture
vapor permeable and liquid impermeable material.
10. A disposable mattress cover second layer according to claim 9,
wherein said moisture vapor permeable and liquid impermeable
material comprises a water transmission rate (WVTR) of at least
about 300 g/m.sup.2.multidot.24 h.
11. A disposable mattress cover comprising the disposable mattress
cover assembly of claim 1.
Description
CROSS REFERENCE TO PRIOR APPLICATION
[0001] This is a continuation of International Application
PCT/US00/33218, with an international filing date of Dec. 8, 2000,
and published in English.
FIELD OF THE INVENTION
[0002] The present invention relates to protective disposable
mattress covers which are moisture vapour permeable and liquid
impermeable and comprise an improved structure. The protective
mattress covers of the present invention can find a variety of
applications wherein moisture vapour permeability combined with
liquid imperviousness are desirable.
BACKGROUND OF THE INVENTION
[0003] Mattress covers, particularly 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. Known mattress covers are
either provided as structures that completely encase a mattress, or
as layers covering at least the portion of the external surface of
the mattress that has to be protected, typically at least a portion
of the surface of the mattress which is intended, in use, to go in
direct or indirect contact with the user, corresponding to the
upper surface in a bed mattress, a cushion or a pillow. Such
mattress covers are provided so that a user can use them in order
to provide a mattress with a protective covering, which accordingly
can be a partial covering, e.g. substantially limited to an upper
surface as explained above, or a total encasing of the
mattress.
[0004] 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.
[0005] 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
to be used as allergen barrier against dust mites must therefore
completely encase the mattress in order to separate the user from
dust mites and related allergens.
[0006] 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 must also have an
allergen barrier capability.
[0007] It is also preferred that mattress covers are disposable,
that is, they can be discarded after use with no need of washing
them.
[0008] Various examples of disposable mattress covers which are at
the same time liquid impermeable and breathable, i.e. moisture
vapour permeable, or at least capable of allowing a certain degree
of air circulation without being truly breathable, are known in the
art.
[0009] For example U.S. Pat. No. 5,727,266 describes a cover for
completely encasing a pillow or a cushion, which is made of liquid
and moisture vapour impermeable material having vent holes, and
also comprising a facing layer of an air permeable material located
on the upper surface of the cover.
[0010] A disposable protective garment or bedding article
constituted of a two-layer laminated structure is also described in
CA 2083630, which is breathable and particularly soft.
[0011] FR 2747899 also discloses a breathable disposable laminated
bed cover in the form of a sheet for covering typically the upper
surface of a bed mattress.
[0012] U.S. Pat. No. 5,950,264 describes a breathable, elastic,
reusable encasing for bedding articles having barrier capability
against dust mites and the related allergens. The encasing
comprises a laminated structure made of an elastic stretch knit
fabric laminated to an elastic, breathable polymeric film.
[0013] Therefore the mattress covers known from the prior art, such
as those mentioned above, either comprise disposable, lightweight,
cheap structures which are liquid impervious and moisture vapour
permeable, and owing to their intrinsic relative weakness are
usually intended for partial encasing of a mattress, typically
covering the upper surface thereof, or alternatively structures
capable of completely encasing a mattress. In this latter case,
however, the known covers are not truly moisture vapour permeable,
such as those described in the above mentioned U.S. Pat. No.
5,727,266, or they comprise rather complex reusable structures such
as those mentioned in U.S. Pat. No. 5,950,264, which are
sufficiently strong in order to withstand their intended use, and
are also in turn rather expensive. Not disposable structures also
imply the need of being washed or sanitised on a regular basis
during their life. Mattress covers intended for complete encasing
of a mattress, such as those described in U.S. Pat. No. 5,950,264,
are also difficult to use, owing to the rather large dimensions of
the mattresses of known conventional sizes, particularly in the
case of bed mattresses.
[0014] There is therefore the need for mattress covers which are
disposable, therefore of cheap and simple construction, liquid
impermeable and moisture vapour permeable, and which can also be
easily used in order to provide conventional mattresses, e.g. bed
mattresses, with a complete encasing, so combining the advantages
of lightweight disposable structures in terms of cost, user
comfort, ease of manufacture and of use, with the increased
protection provided by covers which completely encase a
mattress.
[0015] Preferably such structures should also provide a barrier
against dust mites and the related allergens.
[0016] It is therefore an object of the present invention to
provide a disposable mattress cover assembly for forming a
disposable, liquid impervious and moisture vapour permeable
protecting mattress cover for completely encasing a mattress, which
owing to an improved structure overcomes the above mentioned
problems.
[0017] It is a further object of the present invention to provide a
disposable mattress cover assembly for forming a disposable
protective mattress cover for totally encasing a mattress, which is
liquid impermeable and is further provided with moisture vapour
permeability where it is most desired.
SUMMARY OF THE INVENTION
[0018] The present invention relates to a disposable mattress cover
assembly for forming a protective cover to completely encase a
mattress. The disposable mattress cover assembly comprises a first
layer and a second layer which are separate until use, wherein the
first layer and the second layer have an outer periphery;
[0019] The first layer comprises joining means for cooperation with
cooperating joining means of the second layer, in order to form a
cover to completely encase a mattress, and at least one of the
first layer or of the second layer comprises a moisture vapour
permeable, liquid impermeable material.
[0020] The present invention further relates to the single layers
forming a mattress cover assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is an exploded perspective view of a preferred
embodiment of the disposable mattress cover assembly of the present
invention showing the disposable mattress cover layers before they
are combined together to form the cover, and a bed mattress
comprised therebetween;
[0022] FIG. 2 is a perspective view of the disposable mattress
cover assembly of FIG. 1 after formation of the mattress cover,
seen from the side thereof that is intended to face the user.
DETAILED DESCRIPTION OF THE INVENTION
[0023] According to the present invention, a disposable mattress
cover assembly is provided which comprises a first and a second
layer that are separate until use, and that can be combined
together by a user in order to form a protective cover to
completely encase a mattress comprised therebetween. At least one
of the layers comprises a moisture vapour permeable, liquid
impermeable material, therefore providing the resulting mattress
cover with liquid imperviousness and moisture vapour permeability,
at least on part of its surface.
[0024] The term "mattress", as used herein, 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.
[0025] In the context of the present invention the term "assembly"
indicates the collection of individual elements which are separate
until use, and which are to be put together by a user in order to
form a mattress cover for completely encasing a mattress. The term
"kit" can also be used as an alternative to "assembly" in the
context of the present invention, and having the same meaning as
explained above.
[0026] The term "use", as used herein, refers to the period of time
that starts when the disposable mattress cover assembly, i.e., the
individual elements forming this assembly, is taken by a user and
combined in order to form a mattress cover for completely encasing
a mattress.
[0027] As used herein, the term "separate until use" refers to
individual elements, namely a first and a second layer of the
disposable mattress cover assembly, which can be positioned
substantially independently of each other in order to be combined
to form a mattress cover to completely encase a mattress. This
comprises the preferred case of two layers which are distinct and
separate from each other before use, i.e. in the disposable
mattress cover assembly of the present invention, before they are
combined together in order to form the mattress cover.
[0028] This also comprises the case in which the two layers are
partially joined together before use along a minor portion of the
respective outer periphery, in a way which allows a first layer to
be first laid on a surface, with subsequent positioning of a
mattress thereupon with no need of touching or moving the second
layer, and with final positioning of the second layer over the
mattress, and complete joining of the two layers by means of
cooperating joining means, e.g. along the remaining major portion
of the respective outer periphery, in order to form a mattress
cover to completely encase a mattress. For example, the first and
the second layer of the disposable mattress cover assembly of the
present invention can be two substantially identical rectangular
flat layers joined together along a common edge corresponding to a
side of the rectangle before use. The first layer can be laid on a
surface with the second layer spread open aside, the mattress can
be put onto the first layer, and finally the second layer can be
folded over the mattress and joined to the first layer by means of
the cooperating joining means along the remaining three sides of
the rectangle formed by the outer peripheries thereof.
[0029] This also comprises the case when a first and a second layer
which are distinct and separate from each other are provided
together to the user, for example being sold in a single package
where they are in contact with each other, since they must in any
case be first separated in order to be subsequently combined to
form the mattress cover.
[0030] The terms "joined" or "affixed" or "attached", as used
herein, encompasses configurations where a first member is directly
connected to a second member and configurations where a first
member is indirectly connected to a second member by connecting the
first member to an intermediate member or members which in turn are
connected to the second member.
[0031] FIG. 1 is an exploded view of a preferred embodiment of the
disposable mattress cover assembly 10 of the present invention
before they are combined to form the mattress cover 24 of FIG. 2.
FIG. 1 also shows a mattress 12, which in the preferred embodiment
illustrated herein is a bed mattress having a known
parallelepipedal form, and which is intended to be completely
encased in the mattress cover 24 formed from the mattress cover
assembly 10. The mattress cover assembly 10, which is a bed
mattress cover assembly in the illustrated preferred embodiment,
comprises a first layer 14 and a second layer 16 which are distinct
and separate until use, and both layers 14 and 16 comprise an outer
periphery 18a, 18b, respectively.
[0032] While in principle both the first and the second layer can
be flat, planar layers, which owing to their inherent flexibility
are capable of assuming a suitable three dimensional shape when
combined by the user into a mattress cover for completely encasing
a mattress, it is preferred that at least one of said first or of
said second layer is provided in the disposable mattress cover
assembly already formed into a three dimensional shape such that,
when the layers are combined together, they can form a mattress
cover to completely encase a mattress, which cover has an overall
shape which more suitably approximates the particular shape of the
mattress. Said "pre formed" three dimensional shape of the first
and/or of the second layer is however such that it does not imply
that a mattress has to be actually inserted within a first or a
second layer, e.g. shaped similarly to a sack, a bag, or a tube,
i.e. said preferred pre formed three dimensional shape only has one
major surface or portion.
[0033] Of course, as it is known to the man skilled in the art, by
saying "already formed into a three dimensional shape", with
reference to the first and the second layer of the disposable
mattress cover assembly of the present invention, it is meant that
the layers are rather predisposed to form this shape, e.g. by means
of suitably bonding, stitching, gluing a sheet of material forming
the layer in a way known in the art, or by the inclusion of
elastics or strings in the layer, e.g. along at least part of the
outer periphery of a planar layer, etc., without necessarily
actually showing said shape when they are taken alone, since they
are typically made of flexible material which is not per se capable
of maintaining a three dimensional shape.
[0034] In the preferred embodiment of the present invention
illustrated in FIG. 1 both the first layer 14 and the second layer
16 are provided in the bed mattress cover assembly 10 as being
already formed into a three dimensional shape roughly corresponding
to each of the two halves of a parallelepipedal box which in turn
approximates the known parallelepipedal shape of the bed mattress
12, and is therefore suitable for completely encasing the bed
mattress 12. Each layer 14, 16 comprises a major portion or surface
S1, S2 corresponding to a respective major face of the box, and
four minor portions s, each one corresponding approximately to one
half of each of the four minor faces of the box adjacent to the
major faces, as shown in FIG. 1, wherein when these two layers are
combined together they form a mattress cover 24 having a
parallelepipedal box shape, as better shown in FIG. 2.
[0035] Alternatively, other embodiments of the first and second
layers of a disposable mattress cover assembly are possible
according to the present invention. For example, in the context of
a bed mattress cover assembly capable of forming a bed mattress
cover having a final "box shape" similar to that illustrated in
FIGS. 1 and 2, a first layer can substantially comprise only a
major portion S1 corresponding to a major face of the box, while a
second layer substantially comprises a major portion S2
corresponding to the second major face of the box, and four minor
portions s corresponding to the entire four minor faces of the box
adjacent to both major faces. Of course other combinations are also
possible to provide a disposable mattress cover assembly for
forming a mattress cover to completely encase a mattress, in order
to better accommodate mattresses of various shapes.
[0036] The first layer 14 comprises joining means 20 which, in the
preferred embodiment of FIG. 1, are located along the respective
outer periphery 18a, and are intended for cooperation with
cooperating joining means 22 of the second layer 16, which in the
preferred embodiment of FIG. 1 are also comprised along the
respective outer periphery 18b of said second layer 16. Of course
the terms "joining means" and "cooperating joining means",
respectively referred to elements 20 and 22 in FIG. 1, are
interchangeable, and means 20 and 22 can also be referred to
collectively as "cooperating joining means".
[0037] When the first and the second layers 14 and 16 of the
disposable mattress cover assembly 10 of the present invention are
combined together by a user, by joining the joining means 20 of the
first layer 14 to the cooperating joining means 22 of the second
layer 16, the two layers are actually bonded together along a
common periphery 18, and form a cover 24 which completely encases a
mattress, e.g. a bed mattress 12, as shown in FIG. 2.
[0038] According to the present invention, in order to form a cover
to completely encase a mattress, particularly a bed mattress 12 in
the embodiment illustrated in FIGS. 1 and 2, the user takes the
first layer 14 of the disposable mattress cover assembly 10 and
typically lays it on a surface, preferably a flat surface. In the
case illustrated in FIG. 1, where the mattress is actually a bed
mattress, this surface can advantageously correspond to the bed
structure where the bed mattress is to be positioned, usually the
bed frame, but it may be different for different types of
mattresses. The user then positions the bed mattress 12 over the
first layer 14, and centered with respect to it, duly positioning
the side portions s of the first layer 14 along the side faces of
the mattress 12 and parallel to them. The second layer 16 is
subsequently positioned over the mattress 12 with the respective
side portions s so disposed that the joining means 22 along the
respective outer perimeter 18b are put in contact with the
cooperating joining means 20 along the outer perimeter 18a of the
first layer 14. The user finally bonds together the first layer 14
to the second layer 16 by means of the cooperating joining means 20
and 22, therefore forming a disposable bed mattress cover 24 which
completely encases the bed mattress 12.
[0039] The cooperating joining means 20, 22 can be any type of
suitable joining means known in the art, which can provide a safe
and effective bonding of the first and second layer in order to
form the mattress cover to completely encase a mattress.
[0040] Preferably, the cooperating joining means 20, 22 in the
first and second layer 14, 16 of the disposable mattress cover
assembly 10 of the present invention are releasable, in that they
allow the seal between cooperating joining means 20, 22 to be
released without destroying or damaging the cooperating joining
means 20, 22 themselves, or the structure of the first and second
layers 14, 16 where said cooperating joining means are positioned.
Even more preferably the cooperating joining means 20, 22 are also
refastenable, in order to allow the seal to be released and
subsequently reconstituted between the same first and second layers
14, 16, or alternatively after replacement of one of the
layers.
[0041] Even more preferably, the cooperating joining means 20, 22
are such that they provide a tight seal.
[0042] Such cooperating joining means 20, 22 can for example
comprise adhesive areas, e.g. in a continuos or discontinuous
pattern, in one of the layers, and a target zone in the other layer
where the adhesive is intended to adhere. Adhesive areas can be
protected until use by a removable release paper in order to
prevent the adhesive from drying out or adhering prematurely to
another surface than the target zone. Any suitable adhesive or glue
known in the art can be used herein, for example pressure sensitive
adhesives. The cooperating joining means can also comprise, on both
the first and the second layer, areas of an adhesive that is
capable of adhering only on itself, and this would avoid the use of
a protective release paper. Alternatively, mechanical fastening
means, such as hook and loop fasteners such as those marketed under
the tradename VELCRO, zip fasteners, snaps or holders, buttons,
strings or laces can be used. Plastic fasteners such as those
marketed under the tradename ZIPLOK are also particularly
preferred.
[0043] At least one of the first layer 14 or of the second layer 16
comprises a material which is liquid impermeable and moisture
vapour permeable, preferably air permeable, in order to provide the
disposable mattress cover 24 formed from the disposable mattress
cover assembly 10 of the present invention with breathability
combined with liquid imperviousness. Liquid imperviousness of the
layers 14, 16 forming the disposable bed mattress assembly 10 is
beneficial since it provides the encased mattress with protection
from contaminants, e.g. dust, liquids, or typically bodily fluids.
Moisture vapour permeability is important for comfort reasons, to
the extent that such mattress covers come in direct or indirect
contact with the human body.
[0044] Preferably, the layers of the disposable mattress cover
assembly of the present invention are such that they also provide a
barrier against dust mites and the related allergens, preventing
their egress from within the mattress cover. In this case the
cooperating joining means shall preferably provide a tight
seal.
[0045] Suitable materials for the layers of the disposable mattress
cover assembly of the present invention are also preferably
pleasant to the touch, soft, and have a good drape.
[0046] An advantage of the disposable mattress cover assembly 10 of
the present invention is that it allows a simplified formation of a
mattress cover 24 for completely encasing a mattress, which is
particularly beneficial when the mattress has rather large
dimensions and weight, such as for example for the bed mattress 12
illustrated in FIGS. 1 and 2. It is in fact not necessary to
introduce a mattress into an already partially or totally formed
mattress cover through an aperture, which is particularly difficult
in case of large and heavy mattresses, such as bed mattresses, and
moreover in any case requires that the material forming the cover
is rather strong in order to withstand the stresses implied in this
operation.
[0047] On the contrary, the disposable mattress cover assembly of
the present invention allows the use of materials for the first and
the second layer of the assembly which can be lighter and cheaper,
which is beneficial in the context of a disposable mattress cover
assembly. Moreover, since the materials for the first and the
second layer of the mattress cover assembly of the present
invention need to resist to a lesser stress during the use, they
can be thinner, and therefore provide a better moisture vapour
permeability in addition to liquid imperviousness, and preferably
also to a barrier effect for dust mites and related allergens,
while being also softer and more comfortable for the user. The
disposal of the mattress cover components after use also implies a
lesser waste of materials.
[0048] In the disposable mattress cover assembly of the present
invention the first and the second layer can also comprise
different materials. For example, only the layer that is intended,
in use, to come in direct or indirect contact with a user can be
liquid impermeable and also moisture vapour permeable, for example
the second layer 16 in the embodiment illustrated in FIGS. 1 and 2,
while the other layer, namely the first layer 14 in the illustrated
embodiment, can comprise a cheaper liquid impermeable material
which is not provided with moisture vapour permeability. Both
layers can be generally thin and soft as explained above and still
provide the required function.
[0049] Another advantage of the disposable mattress cover assembly
of the present invention is that, while both the first and the
second layers are disposable, hence are not intended to be washed
or refurbished after use, but are intended to be disposed of, one
of the two layers can nevertheless be changed more often than the
other. For example, in the embodiment of the present invention
illustrated in FIGS. 1 and 2 which relates to a bed mattress cover
assembly and to the respective bed mattress cover, the second layer
16, which is typically intended to come in direct or indirect
contact with the human body, can be disposed of and changed more
often than the first layer 14. Of course in this preferred
embodiment the cooperating joining means 20, 22 are refastenable,
in order to allow a safe breaking of the bond between the first
layer 14 and the second layer 16, and subsequent formation of a new
bond between a new second layer 16 and the first layer 14 still
kept in its original position. This allows less waste of material,
which is particularly beneficial when both layers 14 and 16
comprise a material which is liquid impervious and moisture vapour
permeable, and an even increased ease of use.
[0050] In the preferred embodiment of the present invention
illustrated in FIGS. 1 and 2 the cooperating joining means 20, 22
of the first and second layer 14 and 16 are positioned along the
respective outer peripheries 18a and 18b. However, they can be also
positioned elsewhere, provided that the layers can be joined
together to form a mattress cover to completely encase a mattress,
preferably with a tight seal in case the cover must provide a
barrier against dust mites and related allergens. For example, in
the preferred case of a bed mattress cover assembly similar to that
illustrated in FIG. 1, each of the first and of the second layer
can have a construction similar to that of known bed mattress
covers constituted by a substantially rectangular sheet with
elasticised corners. Each of the first and of the second layer can
be independently applied in a known way to a respective upper and
lower major surface of a bed mattress, also covering the side faces
of the mattress and part of the opposite major surface with the
elasticised corners; this also provides, as it is known in the art,
a stable and releasable connection to the mattress. The first and
the second layer are superimposed to each other in correspondence
to at least part of the side faces of the mattress, and together
completely encase the mattress. The joining means of one layer can
be positioned e.g. along the respective outer periphery, or also
somewhat inboard of such periphery, with the cooperating joining
means of the other layer suitably positioned in order to create the
bond between the layers and form the bed mattress cover to
completely encase a bed mattress. For example the cooperating
joining means can be respectively positioned on the first and
second layer along a line corresponding to the position of the
common periphery 18 illustrated in FIG. 2.
[0051] The first and second layer 14, 16 of the disposable mattress
cover assembly of the present invention can comprise any suitable
known material or structure which is capable of providing a liquid
barrier, and preferably also a barrier against dust mites and
related allergens, in addition to providing moisture vapour
permeability, preferably air permeability, and also having the
required characteristics in terms of softness, thickness and
strength. Such structures or materials can comprise a single layer,
or multiple layers, typically of different materials, laminated
together to form a composite. An example are structures comprising
thermoplastic microporous films, e.g. laminated to fibrous layers
such as nonwoven layers.
[0052] Particularly preferred materials 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. Monolithic films also can be used as such,
or preferably in combination with one or more other moisture vapour
permeable materials in order to form composite structures to be
comprised in the first and/or second layer of the disposable
mattress cover assembly of the present invention.
[0053] Such other 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.
[0054] Said other components may be non-absorbent, absorbent,
liquid-containing, etc.
[0055] Preferably the composite structures described above have a
moisture vapour transfer rate of at least 100 g/m.sup.2.multidot.24
h, more preferably at least 300 g/m.sup.2.multidot.24 h, and most
preferably at least 500 g/m.sup.2.multidot.24 h.
[0056] Examples of known liquid impervious, moisture vapour
permeable materials or composites that can be used in the first and
second layers of the disposable mattress cover assembly of the
present invention are as those disclosed in the documents referred
to below.
[0057] WO 95/16746 discloses films prepared from mixtures of a)
block copolyether ester, block copolyether amides (e.g. Pebax.TM.)
and or polyurethane and b) thermoplastic polymer which is
incompatible with a, and c) a compatibiliser. The films are liquid
impermeable and have moisture vapour permeability of about 700
g/m.sup.2.multidot.day. Also, U.S. Pat. No. 5,447,783 discloses a
vapour permeable water resistant multi component film structure
having at least three layers. The outer layers are hydrophobic
copolyetherester elastomers having a thickness of 1.3-7.6
micrometers and a WVTR of 400-2500 g/m.sup.2.multidot.24 h and the
inner layer is a hydrophilic copolyetherester elastomer having a
thickness of 7.6-152 micrometers and a WVTR of at least 3500
g/m.sup.2.multidot.24 h.
[0058] U.S. Pat. No. 5,445,875 discloses a waterproof, bloodproof
and virusproof breathable laminate. The laminate comprises a
woven/nonwoven fabric and an extruded film such as Hytrel.TM.
having a thickness of about 1 mil (25.4 micrometers).
[0059] Other composite laminates are described for example in U.S.
Pat. No. 5,599,610 which discloses tri-laminated fabric for
surgical gowns comprising outer layers of woven fabric and an inner
layer of a microporous polyurethane membrane. The microporous film
has a thickness of 12-55 micrometers and a MVTR of 1100
g/m.sup.2.multidot.24 h upright and 5500 g/m.sup.2.multidot.24 h
inverted (ASTM E96-B). Polyether-polyurethane adhesive is used to
join the layers.
[0060] Similarly, U.S. Pat. No. 5,532,053 discloses a high moisture
transmission medical film which can be laminated onto a nonwoven
material. The laminate film comprises a first layer of
polyetherester copolymer and second and third layers selected from
a specified group of polymers. The film has a MVTR of greater than
750 g/m.sup.2.multidot.24 h (ASTM F1249) and a thickness of less
than 1 mil (25.4 micrometer) preferably 0.6 mil to 0.75 mil (15-19
micrometers).
[0061] U.S. Pat. No. 4,938,752 discloses absorbent articles
comprising films of copolyether esters which have reduced water
permeability, a water vapour permeability of 500
g/m.sup.2.multidot.24 h (as measured in a specified described test)
and a thickness of 5-35 micrometers. There is no disclosure of a
supportive substrate.
[0062] U.S. Pat. No. 4,493,870 discloses a flexible layered
waterproof product comprising a textile material covered with a
film of a copolyetherester having an MVTR of at least 1000
g/m.sup.2.multidot.24 h (ASTM E96-66) having a thickness of 5 to 35
micrometers.
[0063] GB 2024100 discloses a flexible layered water resistant
article comprising a microporous hydrophobic outer layer which is
moisture vapour permeable but resist liquids and a hydrophilic
inner layer of polyetherpolyurethane having a MVTR of above 1000
g/m.sup.2.multidot.24 h.
[0064] Especially preferred materials to be comprised in the first
and second layers 14, 16 of the disposable mattress cover assembly
of the present invention are thermoplastic compositions described
in our patent applications EP 98110597.6 and EP 98110596.8, and
composite structures comprising said thermoplastic compositions,
also described herein.
[0065] In our patent application EP 98110597.6 entitled "Low
viscosity thermoplastic compositions for moisture vapour permeable
structures and the utilisation thereof in absorbent articles",
filed on 9 Jun. 1998, thermoplastic compositions are disclosed for
making hydrophilic continuous moisture vapour permeable, liquid
impermeable layers or films ("monolithic films") having preferred
characteristics of moisture vapour permeability and liquid
imperviousness. The thermoplastic compositions comprise preferred
thermoplastic polymers such as polyurethanes, poly-ether-amides
block copolymers, polyethylene-acrylic acid copolymers,
polyethylene oxide and its copolymers, poly lactide and copolymers,
polyamides, polyester block copolymers, sulfonated polyesters,
poly-ether-ester block copolymers, poly-ether-ester-amide block
copolymers, polyacrylates, polyacrylic acids and derivatives,
ionomers, polyethylene-vinyl acetate with a vinyl acetate content
of more than 28 weight %, polyvinyl alcohol and its copolymers,
polyvinyl ethers and their copolymers, poly-2-ethyl-oxazoline and
derivatives, polyvinyl pyrrolidone and its copolymers,
thermoplastic cellulose derivatives, or mixtures thereof.
[0066] Particularly preferred thermoplastic polymers are
thermoplastic poly-ether-amide block copolymers (e.g. Pebax.TM.),
thermoplastic poly-ether-ester-amide block copolymers,
thermoplastic polyester block copolymers (e.g. Hytrel.TM.),
thermoplastic polyurethanes (e.g. Estane.TM.), or mixtures
thereof.
[0067] Such thermoplastic polymers or mixture of polymers can be
typically highly viscous in the melted state at the process
conditions that are typical of the known processes of film or layer
formation, e.g. an extrusion process involving a high power screw
extruder. For example they may have a viscosity higher than 5000
poise at a temperature of 20.degree. C. above the DSC (Differential
Scanning Calorimetry) melting point, which is the temperature
identified as that corresponding to the DSC peak, or corresponding
to the highest DSC peak in case of a mixture of polymers showing
more than one peak, and at a frequency of 1 rad/sec.
[0068] The viscosity of the preferred thermoplastic polymers or
mixture of polymers can be preferably adjusted by including in the
thermoplastic composition a suitable plasticiser, or blend of
plasticisers, that is compatible with the thermoplastic polymers
and that lowers the viscosity of the thermoplastic polymer or
mixture of polymers in the melted state.
[0069] The thermoplastic compositions according to EP 98110597.6
comprising the suitable plasticiser or blend of plasticisers have
the following complex viscosities (.eta.*):
[0070] 50 poise<.eta.*<4000 poise, preferably 100
poise<.eta.*<2000 poise, more preferably 100
poise<.eta.*<1000 poise, at a frequency of 1 rad/s at a
temperature of 210.degree. C. or less and .eta.*<2000 pose,
preferably .eta.*<1000 poise, more preferably .eta.*<500
poise, at a frequency of 1000 rad/s at a process temperature (T) of
210.degree. C. or less, wherein .eta.* represents the complex
viscosity of the thermoplastic polymeric composition. Preferably
the temperature T is 200.degree. C. or less and more preferably
180.degree. C. or less and most preferably from 200.degree. C. to
50.degree. C.
[0071] The thermoplastic compositions having the complex viscosity
described allow for a film or layer to be coated onto a substrate
using typical coating conditions and apparatuses known in the art
for the coating of low viscosities hot melt compositions in a layer
having a required thickness onto a substrate, while also keeping
the advantageous characteristics of the preferred thermoplastic
polymers in providing hydrophilic continuous moisture vapour
permeable, liquid impermeable layers or films.
[0072] Thermoplastic compositions having such viscosities can also
provide very thin films or layers.
[0073] Suitable plasticisers or blend of plasticisers for adjusting
such viscosity can be selected from the group consisting of citric
acid esters, tartaric acid esters, glycerol and its esters,
adipates, sebacates, sorbitol, epoxidized vegetal oils, polymerised
vegetal oils, polyols, phthalates, liquid polyesters, glycolates,
p-toluene sulfonamide and derivatives, glycols and polyglycols,
sorbitan esters, phosphates, monocarboxylic fatty acids
(C.sub.8-C.sub.22) and their derivatives, and mixtures thereof.
This allows to utilise with these preferred compositions typical
process conditions known in the art for the direct coating of low
viscosity hot melts onto a substrate in order to form a moisture
vapour permeable, liquid impervious film or layer.
[0074] It has also been found according to our patent application
EP 98110596.8 entitled "Low viscosity thermoplastic compositions
for structures with enhanced moisture vapour permeability and the
utilisation thereof in absorbent articles", filed on 9 Jun. 1998,
that by further selecting the plasticiser or blend of plasticisers
to be comprised in the thermoplastic composition from the group of
hydrophilic plasticisers consisting of acids, esters, amides,
alcohols, polyalcohols, or mixtures thereof, the advantage of an
enhanced moisture vapour permeability of the resulting layer or
film formed from the thermoplastic composition is also achieved,
when compared to a corresponding film or layer formed from a
thermoplastic composition comprising the same thermoplastic
polymer, but without the plasticiser.
[0075] The preferred hydrophilic plasticiser or blend of
hydrophilic plasticisers can also adjust the viscosity of the
thermoplastic composition to the preferred values in order to make
it processable by coating said thermoplastic composition onto a
substrate in a layer or film having a desired thickness.
[0076] Preferred hydrophilic plasticisers according to EP
98110596.8 are citric acid esters, tartaric acid esters, glycerol
and its esters, sorbitol, glycolates, and mixtures thereof.
[0077] Preferably the thermoplastic compositions according to EP
98110597.6 and EP 98110596.8 comprises from 10% to 80%, more
preferably from 25% to 70% by weight of the thermoplastic
composition, of the thermoplastic polymer or mixture of polymers,
and from 20% to 90%, preferably from 30% to 75% by weight of the
thermoplastic composition, of the suitable plasticiser or blend of
plasticisers.
[0078] The thermoplastic compositions according to EP 98110597.6
and EP 98110596.8 may in addition comprise additional optional
components to further improve the processibility of the
compositions and also the mechanical characteristics as well as
other characteristics as tackiness, resistance to ageing by light
and oxygen, visual appearance etc., of the films or layers formed
from such thermoplastic compositions.
[0079] Such optional components include tackifying resins or blends
of tackifying resins having a softening point of 125.degree. C. or
less. According to EP 98110597.6 and EP 98110596.8 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 resins, aromatic resins, synthetic C.sub.5 resins,
mixtures of synthetic C.sub.5-C.sub.9 resins, and mixtures thereof.
Other optional components of said thermoplastic compositions
include anti-oxidants, anti-ultraviolets, pigments and mixtures
thereof, which may be present within the composition at a level of
up to 10% by weight of the composition.
[0080] A thermoplastic composition according to EP 98110597.6 or EP
98110596.8 can be manufactured with a process that will typically
comprise the steps of providing the thermoplastic polymer or
mixture of polymers and the suitable plasticiser or blend of
plasticisers, heating the components and compounding them, e.g.
with a known suitable mixer to form the thermoplastic composition
in the molten state having the desired complex viscosity
.eta.*.
[0081] According to EP 98110597.6 or EP 98110596.8 a moisture
vapour permeable, liquid impervious layer can be formed from the
thermoplastic composition of the present invention by coating said
thermoplastic composition onto a substrate. The films or layers
formed from the thermoplastic compositions of the present invention
preferably have a moisture vapour transport rate of at least 100
g/m.sup.2.multidot.24 h, preferably at least 300
g/m.sup.2.multidot.24 h, most preferably at least 500
g/m.sup.2.multidot.24 h with a thickness of the layer of at least
0.5 .mu.m.
[0082] A process for making a layer or film from a thermoplastic
composition according to EP 98110597.6 or EP 98110596.8 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. While
said substrate can be simply a formation substrate, onto which the
thermoplastic composition is coated in order to form a film or
layer of the desired thickness which is subsequently separated from
said substrate and used as such, in a preferred embodiment of 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 preferably moisture vapour
permeable.
[0083] Such embodiment provides a moisture vapour permeable, liquid
impervious composite structure wherein the contribution of the
layer formed from the thermoplastic composition of the present
invention to the performance of the composite material resides only
in the provision of a liquid barrier and hence could be
advantageously provided as thinly as possible. The remaining
performance physical criterion being preferably provided by the
provided substrate, that therefore preferably acts also as a
support layer. Typical thicknesses of the layer of the
thermoplastic composition applied onto a suitable substrate to form
a composite structure according to the present invention range from
2 .mu.m to 200 .mu.m.
[0084] The substrate, or support layer may be any useful layer
which is preferably also moisture vapour permeable, preferably
having a moisture vapour permeability of at least 100
g/m.sup.2.multidot.24 h, more preferably at least 300
g/m.sup.2.multidot.24 h, and most preferably at least 500
g/m.sup.2.multidot.24 h.
[0085] Suitable substrates for use herein as support layers include
two dimensional, planar micro and macro-porous films;
macroscopically expanded films; formed apertured films; nonwoven
and woven layers. According to EP 98110597.6 and EP 98110596.8 the
apertures in said layer may be of any configuration, but are
preferably spherical or oblong and may also be of varying
dimensions. The apertures preferably are evenly distributed across
the entire surface of the layer, however layers having only certain
regions of the surface having apertures are also envisioned.
[0086] Suitable two dimensional porous planar layers may be made of
any material known in the art, but are preferably manufactured from
commonly available polymeric materials. Suitable materials are for
example Goretex.TM. or Sympatex.TM. type materials well known in
the art for their application in so-called breathable clothing.
Other suitable materials include XMP-1001 of Minnesota Mining and
Manufacturing Company, St. Paul, Minn., U.S.A. and Exxaire
XBF-101W, supplied by the Exxon Chemical Company. As used herein
the term two dimensional planar layer refers to layers having a
depth of less than 1 mm, preferably less than 0.5 mm, wherein the
apertures have an average uniform diameter along their length and
which do not protrude out of the plane of the layer. The apertured
materials for use as a backsheet in the present invention may be
produced using any of the methods known in the art such as
described in EPO 293 482 and the references therein. In addition
the dimensions of the apertures produced by this method may be
increased by applying a force across the plane of the backsheet
layer (i.e. stretching the layer).
[0087] Suitable apertured formed films include films which have
discrete apertures which extend beyond the horizontal plane of the
garment facing surface of the layer towards the core thereby
forming protuberances. The protuberances have an orifice located at
its terminating end. Preferably said protuberances are of a funnel
shape, similar to those described in U.S. Pat. No. 3,929,135. The
apertures located within the plane and the orifices located at the
terminating end of protuberance themselves maybe circular or non
circular provided the cross sectional dimension or area of the
orifice at the termination of the protuberance is smaller than the
cross sectional dimension or area of the aperture located within
the garment facing surface of the layer. Preferably said apertured
performed films are uni directional such that they have at least
substantially, if not complete one directional fluid transport
towards the core.
[0088] Suitable macroscopically expanded films for use herein
include films as described in for example in U.S. Pat. Nos.
4,637,819 and 4,591,523.
[0089] Preferred support layers for use herein include woven and
nonwoven layers, most preferably hydrophobic fibrous layers such as
hydrophobic nonwoven.
[0090] The composites of this preferred embodiment according to EP
98110597.6 and EP 98110596.8 are particularly advantageous as they
allow the possibility of providing a composite wherein the
thermoplastic composition may be coated onto the support substrate
as a 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.
[0091] 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.
[0092] At least at the coating temperature, the preferred
thermoplastic compositions according to EP 98110597.6 or EP
98110596.8 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.
[0093] Preferably the moisture vapour permeable, liquid impervious
layers and composites formed from the thermoplastic compositions
according to EP 98110597.6 or EP 98110596.8 have an overall
moisture vapour transfer rate of at least 100 g/m.sup.2.multidot.24
h, more preferably at least 300 g/m.sup.2.multidot.24 h, and most
preferably at least 500 g/m.sup.2.multidot.24 h.
[0094] A moisture vapour permeable, liquid impervious composite
structure formed by coating the thermoplastic composition according
to EP 98110597.6 or EP 98110596.8 onto a suitable substrate, e.g. a
nonwoven substrate, finds particular utility as the material for
forming the first and second layer of a disposable mattress cover
assembly according to the present invention. Preferably the first
and second layer of a disposable mattress cover assembly according
to the present invention comprise a laminated structure as those
disclosed above with the thermoplastic composition intended to face
inwardly of the formed disposable mattress cover, and therefore to
come in contact with the mattress comprised therebetween.
[0095] It is also particularly preferred that, in this latter case,
the preferred thermoplastic composition provides an increased
friction with the surface of the mattress with which said
composition is intended to come in contact. According to our patent
application entitled "Disposable, moisture vapour permeable, liquid
impermeable mattress cover having an improved structure for
increased stability" filed on the same day as the present
application (P&G Case CM2250F), it has been discovered that by
suitably further selecting the tackifier resin, or blend of
tackifier resins, to be added to the thermoplastic composition, it
is possible to adjust the residual tackiness of said thermoplastic
composition at room temperature, i.e. in the solidified
thermoplastic composition constituting the layer of the moisture
vapour permeable, liquid impermeable laminated structure comprised
in the first and/or second layer of the mattress cover assembly of
the present invention, which layer is intended to directly contact
the mattress in use. This in turn allows an adjustment of the
friction that is established, in the use conditions, between the
layer of said thermoplastic composition comprised in the disposable
mattress cover assembly of the present invention, and the mattress
surface, when the mattress cover formed from the mattress cover
assembly is typically subjected to compression against the mattress
itself. An increased friction provides in fact a better stability
of the liquid impermeable, moisture vapour permeable mattress cover
formed from the assembly of the present invention with respect to
the mattress, avoiding or at least reducing the relative movements
between mattress cover and mattress which can be induced in use,
for example by the user's movements, e.g. during the sleep, when
the mattress is a bed mattress or a pillow, and the mattress cover
is a bed mattress cover or a pillow cover. Risk of misplacement of
the mattress cover during the use is therefore greatly reduced.
This also reduces the stress applied in use to the cooperating
joining means which connect the first and the second layers forming
the mattress cover. Moreover, this in turn allows the use of
lighter and cheaper materials for the disposable mattress cover
layers of the assembly of the present invention, which is
beneficial in the context of a disposable structure. Since said
materials, preferably comprising the preferred thermoplastic
compositions layered onto a fibrous substrate to form a composite
moisture vapour permeable, liquid impermeable structure, comprised
in the mattress cover layers of the assembly of the present
invention need to resist to a lesser stress during the use, they
can be thinner, and therefore provide a better moisture vapour
permeability in addition to liquid imperviousness, while being also
softer and more comfortable for the user. The disposal of the
mattress cover layers after use also implies a lesser waste of
materials.
[0096] By suitably selecting the tackifier resin or blend of
tackifier resins according to the above mentioned application 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. In other
words, the friction between the layer of thermoplastic composition
comprised in the mattress cover layers of the assembly of the
present invention and the mattress can be increased such that the
mattress cover layers can actually stick to the mattress, owing to
the thermoplastic composition which can be formulated in order to
behave like a pressure sensitive adhesive. Residual tackiness of
the thermoplastic composition at room temperature can be suitably
tailored according to the present invention since a smooth
transition exists between increasing friction and actual
adhesiveness.
[0097] Preferred tackifier resins, or blend of tackifier resins
according to the present invention still have a softening point of
125.degree. C. or less, and are selected from the group consisting
of rosin and rosin esters, terpene-phenolic resins, aromatic
resins, and mixtures thereof.
[0098] More preferably, the thermoplastic compositions according to
the above mentioned application 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.degree. 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.degree. C.
[0099] The presence in the blend of tackifier resins of a certain
amount of one or more tackifier resins which are liquid at room
temperature is preferred since said resin or resins, in addition to
adjusting the residual tackiness of the layer formed from the
resulting thermoplastic composition, also contribute to lower the
viscosity of the composition itself at the process conditions, in
combination with the selected suitable plasticiser or blend of
plasticisers as disclosed in EP 98110597.6 or EP 98110596.8.
[0100] Said preferred blend of tackifier resins therefore provides
a thermoplastic composition, to be comprised in a first and/or a
second layer of the disposable, moisture vapour permeable, liquid
impermeable mattress cover assembly of the present invention, which
is easily processable. Moreover the preferred blend of tackifier
resins allows to adjust the residual tackiness of the resulting
thermoplastic layer made from the thermoplastic composition, and
therefore ultimately the friction between the mattress cover formed
from the mattress cover assembly of the present invention and the
mattress in use conditions, i.e. when the thermoplastic composition
is coated preferably onto a nonwoven substrate to form a composite
structure comprised in the first and/or second layer of the
disposable mattress cover assembly of the present invention, with
the layer of thermoplastic composition intended to come in direct
contact with the mattress. This is beneficial as explained
above.
[0101] The particularly preferred tackifier resins, or blend of
tackifier resins, can be comprised in the same thermoplastic
compositions according to EP 98110597.6 or EP 98110596.8, but with
a different percentage ranging from 2% to 60%, preferably from 5%
to 50%, more preferably from 10% to 40%, by weight of said
thermoplastic composition, of a tackifier resin or blend of
tackifier resins.
[0102] Of course, it is not necessary that both the first and the
second layer of the disposable mattress cover assembly according to
the present invention provide moisture vapour permeability, in
addition to liquid imperviousness and preferably barrier to dust
mites and related allergens. Therefore one of the layers, for
example the first layer 14 in the embodiment illustrated in FIGS. 1
and 2, can be only liquid impervious and not moisture vapour
permeable, and therefore typically also provide a barrier to dust
mites and related allergens. Any know suitable material, such as
for example known thermoplastic films, can be selected for a layer
which is only liquid impervious. Alternatively, only selected
portions of the first or of the second layers of the disposable
mattress cover assembly of the present invention can be provided
with known means with moisture vapour permeability, in addition to
liquid imperviousness.
[0103] According to the present invention the complex viscosity
.eta.* is measured using a Rheometer RDA-II available from
Rheometrics Co. Moisture vapour permeability is measured as Water
Vapour Transmission Rate (WVTR) at 23.degree. C. according to the
ASTM E-96 "Upright Cup" method. The softening point of the resins
is measured according to the Ring and Ball ASTM E28 method.
* * * * *