Air-permeable and waterproof diaper cover

An air-permeable and waterproof diaper cover comprises a front body part and a rear body part and two wings attached to the left and right upper sides of the rear body part. The rear body part comprises at least a section of waterproof and stretching material, and the front body part comprises at least a section of air-permeable and water-repellent material, whereby the combination and location of such materials prevents leakage of liquid while permitting air and gas circulation.

BACKGROUND OF THE INVENTION 
This invention relates to air-permeable and waterproof diaper covers. 
More particularly, this invention relates to a diaper cover for babies, 
infants and disabled adults. 
In this invention, the term "waterproofing" means the property which 
prevents the penetration of water by coating and filling the gaps between 
warps and woofs together with the gaps between fibres of a knitted fabric 
and forming a continuous film on the knitted fabric. In such waterproof 
finish, the surface of the knitted fabric is covered to form a wall, and 
with the exception of a special condition the knitted fabric interrupts 
the passage of gases and liquids completely. Normally, the finished fabric 
resists a fair amount of water pressure, however, it has not provided 
resistance to wetting. 
A water proofing and stretching material is a material finished by a 
synthetic resin as a waterproofing agent. 
The term "water repellency" means the property which resists wetting by 
coating the fibres of a knitted fabric with a hydrophobic material or by 
directly combining hydrophobic groups to the fibre molecules. Finished 
clothes retain air permeability together with porosity, but depending on 
the construction of the clothes and the method of water repellent 
finishing, the resistance to water pressure changes. 
For example, air permeable and stretching material is obtained by coating 
polyvinyl chloride resin on plain cloth of polyester 100%, 75 denier, 28 
gauge, smooth knitting. By JIS L 1079-1976Chemical Fibre Fabric Testing 
Method, said material showed water pressure resistance exceeding 500 mm (a 
method based on low water pressure), while the air permeability was zero. 
But the film shows a good bonding property to plain cloth and has 20% 
lateral elongation. Thus, the characteristic stretching property of plain 
knitted cloth is preserved. 
Because the polyvinyl chloride resin has some elastic property, even if the 
plain cloth is elongated, holes are not formed on the surface of the plain 
cloth thereby damaging the waterproofing property. 
The term "air-permeable and water-repellent material" means a material, 
such as knitted fabric, which is made of synthetic fibres treated by an 
impregnation of synthetic resin such as of the fluorocarbon type, silicone 
type or the like to provide water repellency. The material is subjected to 
heat treatment to retain water-repellency. The treating temperature 
differs or varies depending on the kind of synthetic fibres. When the 
material is polyester fibres heat treatment is effected at approximately 
170.degree. C., and the result is material having a good feeling and 
retaining water repellency. 
For example, air-permeable and water repellent material is obtained by 
impregnating a silicone resin liquid on plain cloth of polyester 100%, 100 
denir, 24 gauge, smooth knitting, finished weight 260 g/m. This plain 
cloth is dipped in silicon resin liquid, the resin is deposited on the 
surfaces of the fibres of said cloth, dried and then finished. In relation 
to the term "smooth knitting", the two stages of smooth knitting means a 
doubled form of the rubber knitting by means of both sides of a circular 
knitting machine, and the three stages smooth knitting means a tripled 
form of the rubber knitting. By the above mentioned JIS L 1079-1976 
Testing Method, said material showed water pressure resistance exceeding 
160 mm (a method based on low water pressure method), water repellent 
degrees exceeding 70 (a method based on spraying method), and air 
permeable degrees exceeding 20 cc/cm.sup.2 /sec. 
The term "air-permeable material" means a cloth, such as a normal knitted 
fabric, that is not treated for water-repellency or waterproofness. The 
material has little resistance to water pressure or to passing water 
therethrough, but provides sufficient air-permeability and stretching 
properties. 
Principally, a diaper cover is required to have water-proofness and 
air-permeable properties, even though the two properties differs 
substantially in their functional properties and characteristics. A diaper 
cover which attaches importance to waterproof properties prevents leakage 
after urination, but because of the lack of permeability, the diaper cover 
is liable to become foul or stuffy in the interior thereof. On the other 
hand, a diaper cover which attaches importance to air-permeability 
provides for permeation of air and gases and relieves foulness and 
stuffiness in the interior of the diaper cover, but it is liable to leak 
urine through the openings used for air permeation. 
Accordingly, there has been a need for many years for a diaper cover which 
has both air-permeability and waterproof properties. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a diaper 
cover which overcomes the disadvantages of known prior art diaper covers. 
Another object of the present invention is to provide a air-permeable and 
waterproof diaper cover whereby leakage of liquid is prevented and the 
diaper cover is allowed to breathe. 
This invention provides an air-permeable and waterproof diaper cover which 
comprises body parts including a front body part and a rear body part, two 
wings fitted to the left and right upper sides of the rear body part 
individually, two dams provided at two concave portions at both central 
sides of the body parts, a waist elastic, crotch elastics, fastening means 
such as snap fasteners, velvet fasteners or the like and is characterized 
in that the rear body part comprises at least a section of waterproof and 
stretching material, and the front body part comprises at least a section 
of air-permeable and water-repellent material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As regards to diaper cover styles, there are various styles: open styles, 
panty styles and new-born baby styles. Diaper covers of the open style 
will be described. 
FIG. 1 shows a diaper cover having a body part 1 which consists of a front 
body part 3 and a rear body part 5. On both upper sides of the rear body 5 
wings 11, 13 are fitted by means of bonding or seaming. 
The general area represented by the circular portion 1 of the rear body 
part 5 is subjected to the most weight by the user and is wetted the most. 
Accordingly, the inner lining material of this portion 1 should provide 
complete waterproofing. Also, since this portion 1, especially in infants, 
is influenced by the motion of the body, it is advantageous if this 
portion of the diaper cover is provided with stretching properties. 
The general area represented by the circular portion m is less subjected to 
the weight of the user than the circular portion 1, especially in infants. 
The frequency that it is subjected to the weight of the user is also 
significantly lower. This is because the portion m is subjected to the 
weight of the user only when the user's body lies facing upwardly and is 
wetted only when the entire diaper cover is wetted. The above examples do 
not apply, however, to heavy disabled persons who lie in bed continuously 
or to babies or infants who always lie face up. 
The function of the rear body part 5 and front body part 3 which together 
constitute the body part 1 has been described, but the diaper cover 
provides some other elements which relate closely to the fundamental roles 
of the diaper cover. These members include dams 19, 21 and crotch elastics 
25, 27 fitted together with the dams to provide concave portions 15, 17 of 
the body part 1. The concave portions are often subjected to wetting. The 
openings of the crotch portions are fastened by crotch elastics 25, 27. In 
addition to said crotch elastics there are doubly fitted dams 19, 21 which 
are formed by water proofed and stretching material; the edge or ridge 
portions of said dams are covered by the same type of elastic fibres as 
the crotch elastics 25, 27. The openings of the crotch portions are 
fastened by said dams respectively. In prior art diaper covers, these 
portions contain seam holes through which wetting is effected. Furthermore 
these portions require sufficient stretching properties. 
The general areas shown as circular portions n are not subjected to the 
weight of the user as often as the circular portions l and m, and the 
chance of such portions becoming wet is reduced. Portions n are subjected 
to the user's weight only when the user lies on one side, and such 
portions are less subjected to wetting. 
Accordingly, in consideration of the movement of the user, the general 
areas represented by the circular portion 1 and the circular portion m 
require a completely water-proof and stretchable material. 
Next, with regard to the general area represented by the circular portion o 
positioned in the front body part 3, except when the user lies face down 
or the user is held, almost no weight is placed on such portion and also 
it is less wetted than the portions l, m and n. 
In FIG. 1, numerals 7 and 9 represent the upper left and right sides of the 
rear body part 5 respectively. Numerals 15 and 17 represent concave 
portions or dam fitting portions provided on both sides of the body part 
1. Numeral 23 represents a waist elastic and numerals 29 and 31 represent 
snap fastners. 
However, the problem of wetting through the seam holes can be partially 
solved by the use of water-repellent sewing threads, and resolved 
completely by the application of bonding techniques such as high frequency 
bonding or the like. 
Preferably, the bonded portion has tensile strength exceeding 2.5 kg/3 cm. 
This invention provides an air-permeable and waterproof diaper cover 
utilizing at least a section of waterproof and stretching material for the 
rear body part 5, at least a section of air-permeable and water-repellent 
material for the front body part 3, and bonding of certain seams such as 
the seam 33 between the rear body part 5 and the front body part 3 and the 
crotch elastic portions 25, 27 which are equal to the fitting portions of 
the dams 19, 21 and the like. 
In a preferred embodiment of the present invention, an air-permeable and 
waterproof diaper cover is characterized in that the rear body part 
consists of a piece of waterproof and stretching material, and the front 
body part consists of a piece of the air-permeable and water-repellent 
material. 
FIGS. 2 to 4 show a diaper cover according to one embodiment of this 
invention, which is in accordance with the requisites of the above 
mentioned diaper cover and which has a simple construction. In this 
embodiment the rear body part 5 is formed from a piece of waterproof and 
stretching material, and the front body part 3 is formed from a piece of 
the air-permeable and water-repellent material. 
In all embodiments of the invention, wings 11, 13 are fitted to the left 
and right upper sides 7, 9 individually by means of sewing or bonding. 
Because the rear body part 5 and the front body part 3 are connected by a 
bonding means such as high frequency bonding, leakage of urine through the 
overlapping portions of the bonded seam is prevented. 
Because the dams 19, 21 are formed either by an air-permeable and 
water-repellent material or by a waterproof and stretching material, such 
material is bonded to the edges of the concave portions 15, 17 at the 
central and both sides of the body part 1 by similar means as described 
above, and leakage of urine from the dam fitting portions is thereby 
prevented. 
In another preferred embodiment of the present invention, the inner lining 
of the rear body part consists of a piece of waterproof and stretching 
material, the outside of the rear body part consists of a section of 
air-permeable, and water-repellent material or air-permeable material. The 
front body part also consists of a section of air-permeable and 
water-repellent material, and the outer surface material of the rear body 
part and the front body part are made from one piece of cloth material. 
FIG. 5 shows the above described embodiment in which the front body part 3 
is formed by one piece which is of an air-permeable and water-repellent 
material and forms a seamless continuation of the outer surface 5a of the 
rear body part 5. The inner lining rear body part 5b is formed by a 
waterproof and stretching material. The rear body part 5b is terminated at 
the lower edge 33' and said rear body part is bonded to said outer surface 
at said lower edge. 
In a further embodiment of the present invention, an air-permeable and 
waterproof diaper cover is characterized in that the inner lining of the 
rear body part consists of a piece of waterproof and stretching material, 
the outer side of the rear body part consists of a piece of air-permeable 
and water-repellent material or a piece of air-permeable material. The 
inner lining of the front body part consists of a piece of air-permeable 
and water-repellent material, the outer surface of the front body part 
consists of a piece of air-permeable and water-repellent material or 
air-permeable material, and the outer surface material of the rear body 
part and the outer surface material of the front body part are made from 
one piece of such material. 
FIGS. 6 to 8 show the above embodiment according to the invention. The 
outer surface material 3a, 5a are formed as one piece from an 
air-permeable and water-repellent material or air-permeable material and 
the lining material of the front body part and rear body part 3b, 5b are 
formed by an air-permeable and water-repellent material and by a 
water-proof and stretching material respectively, the two materials being 
bonded together at an overlapped edge portion or seam 33 having a curved 
configuration. 
However, as shown in other alternate embodiments, the overlapped bonded 
edge portion 33 may form a straight line. 
As indicated above, when one piece of air-permeable and water-repellent 
material or of air-permeable material is used for the outside surface of 
body parts 3a and 5a, the inner lining parts 3b and 5b are protected by 
such outer material. 
In a further embodiment of the present invention, an air-permeable and 
waterproof diaper cover is characterized in that the inner lining of the 
rear body part consists of a piece of air-permeable and water-repellent 
material, an intermediate material of the rear body part consists of a 
piece of waterproof and stretching material, and an outer surface material 
of the rear body part consists of air-permeable and water-repellent 
material or of air-permeable material. The lining of the front body part 
consists of air-permeable and water-repellent material, the outer surface 
of the front body part consists of a piece of air-permeable and 
water-repellent material or of air-permeable material, and the outer 
surface of the rear body part and the outer surface of the front body part 
are each made from a single piece of material. 
FIGS. 9 to 11 show the above embodiment of the diaper cover according to 
the invention, FIG. 10 particularly shows two pieces of an air-permeable 
and water-repellent material (or alternatively one piece of air-permeable 
material) being used. This one piece of air-permeable and water-repellent 
material continuously forms the outer front body part 3a and the outer 
rear body part 5a. Another piece forms the lining surfaces 3b and 5b. A 
waterproof and stretching material is sandwiched as the intermediate 
material 5c between the rear body parts 5a and 5b. 
In the use of the above diaper cover, urine permeates the lining material 
of the rear body part 5b, but it does not penetrate the outer surface 
material of the rear body part 5a because of the intermediate waterproof 
and stretching material 5c. 
The diaper cover, as indicated above, has long durability because the 
waperproof and stretching material used as the intermediate material 5c is 
protected by the air-permeable and water-repellent materials or the 
air-permeable material used therewith. 
In the embodiment of FIGS. 2 to 11, the four kinds of diaper covers 
disclosed therein are based on the combinations of the air-permeable 
material, the air-permeable and water-repellent material, and the 
waterproof and stretching material. These combinations provide a 
air-permeable and waterproof diaper cover by utilizing the advantages 
characteristic of each such material. 
In other preferred embodiments of the present invention, the air-permeable 
and waterproof diaper cover is characterized in that the two dams consist 
of the air-permeable and water-repellent materials or waterproof and 
stretching material, such materials being bonded to the edges of the 
concave portions at the central part of both sides of the body parts 
respectively, and elastic or rubber marginal portions at the crotch edge 
portions of the dams consist of stretching materials having air 
permeability and water-repellency. 
In the embodiments of FIGS. 1, 6, 9, 12, 15 and 18 dams 19, 21 consist of 
the air-permeable and water-repellent material or the waterproof and 
stretching material. such materials being bonded to edges of the concave 
portions 15, 17 at both central sides of the body part. The elastic 
portions of the crotch elastic 25, 27 and the edge portions of the dams 
consist of elastic material having air-permeability and water-repellency. 
Because, the amount of urine from a baby is small while that of a disabled 
adult is large and the amount differs in day time and night individually, 
the materials for dams 19, 21 are selected from either the air-permeable 
and water-repellent material or the waterproof and stretching material 
depending on its use. 
In one preferred embodiment of the present invention, the air-permeable and 
waterproof diaper is characterized in that the air-permeable and 
water-repellent material forming the front body part is bonded to the 
waterproof and stretching material forming the rear body part at an 
overlapping section. 
The bonding of the air-permeable and water-repellent material forming the 
front body part 3 and the waterproof and stretching material forming the 
rear body part 5 is effected by a method such as high frequency bonding to 
improve waterproofness. 
In another preferred embodiment of the present invention, the air-permeable 
and waterproof diaper cover is characterized in that both upper sides of 
the rear body part to which two wings are fitted consist of at least two 
pieces of air-permeable and water-repellent material, or two pieces of 
air-permeable and water-repellent material and two pieces of air-permeable 
material. 
FIG. 12 shows a further alternate embodiment of a different type of a 
diaper cover according to the invention in which constant portions at the 
upper left side and upper right side of the rear body part 5, that is the 
portions which are connected to wings 11, 13 respectively are cut away, 
and instead two pieces of the air-permeable and water-repellent material 
are attached, and if desired, bonded with the neighborring portions. 
The diaper cover shown in FIGS. 12 to 14 is a modification of that shown in 
FIG. 2, and in the embodiment of FIGS. 12 to 14, both upper side sections 
7, 9 of the rear body part 5 are formed by a piece of air-permeable and 
water-repellent material. 
As seen in the drawings, since the rear body part 5, both upper sides of 
the rear body part 7, 9 and the front body part 3 all have a configuration 
similar to a rectangle or trapezoid, the diaper cover has less waste 
material based on cut pieces of blank material. 
The diaper cover shown in FIGS. 15 and 16 is a modified version of the 
diaper cover shown in FIGS. 5 and 7. In the embodiment of FIGS. 15 and 16, 
both upper sides 7, 9 of the rear body part 5 are formed by pieces of the 
air-permeable and water repellent material or pieces of the air-permeable 
and water-repellent material and a piece of the air-permeable material, 
which contains at least a small rectangular piece of such material, 
respectively. Both sides 7, 9 are bonded to the inner lining material of 
the rear body part 5b formed by the waterproof and stretching material at 
bonding seams 35 and 37. 
In a further alternate embodiment shown in FIG. 17, the lining material of 
both upper sides 7, 9 is eliminated from the diaper cover as compared to 
the embodiment of FIGS. 15 and 16. In the FIG. 17 embodiment, a lining 
material for the rear body part 5b is formed by the waterproof and 
stretching material which is bonded to the outer surface material of the 
rear body part 5a formed by the air-permeable and water-repellent material 
at both side edges 39, 41 of the lining material 5b. 
FIGS. 18 and 19 show a further alternate diaper cover which is a modified 
version of that shown in FIGS. 9 to 11. In the embodiment of FIGS. 18 and 
19, an intermediate material 5c is formed by a waterproof and stretching 
material which has a rectangular shape. Cutting of the material is simple 
and little waste material is produced. The neighboring portions to both 
upper sides 7, 9 of the intermediate material 5c at the rear body part 
have free ends which do not require bonding as is not required at the 
lower end of the intermediate cloth 5c. 
Also, edge portions of the outer surface and the inner lining are bonded to 
each other by means of piping or overlocking. 
The above three different embodiments of diaper covers are suitable for use 
in the day time since the skin of the user's body is activated and liable 
to be stuffy. 
As mentioned above, each type of diaper cover according to the invention 
may be produced by utilizing the special functional characteristics of 
each portion required in a diaper cover selecting materials suited to such 
portions, and then combining them. 
In accordance with the present invention the following advantages are 
obtained. 
(1) The combination of the materials required for each portion of the 
diaper cover allows the diaper cover to provide sufficient 
air-permeability and waterproofness but does not permit leakage of urine. 
(2) The diaper cover provides sufficient air-permeability and stretching 
properties and is comfortable for the user. 
(3) The diaper cover is designed to avoid waste, with the cutting loss 
reduced significantly due to the blocking of the body parts which become 
miniaturized. For example, portion o and portion l in FIG. 1 are 
separated, or portions n, portion l and portion o are separated relative 
to each other and concave portions and convex portions around each cut 
piece are less. Such diaper cover is produced inexpensively making use of 
relatively small amounts of materials and by simple manufacturing 
procedures.