U.S. patent number 3,639,199 [Application Number 04/885,201] was granted by the patent office on 1972-02-01 for reinforced laminate product.
This patent grant is currently assigned to Consolidated Paper (Bahamas) Limited. Invention is credited to Joseph Maria Bentvelzen, Theodorus Gerardus Brandts, Joseph Alois Lichtenberger.
United States Patent |
3,639,199 |
Brandts , et al. |
February 1, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
REINFORCED LAMINATE PRODUCT
Abstract
A laminated, nonwoven fabric product and method of making same
comprising a central reinforcing web of fibrillated sheet plastic
material having a plurality of substantially parallel fibers
integrally interconnected at spaced points along their length and
outer layers formed of cellulosic material.
Inventors: |
Brandts; Theodorus Gerardus
(Grand'Mere, Quebec, CA), Lichtenberger; Joseph Alois
(Grand'Mere, Quebec, CA), Bentvelzen; Joseph Maria
(Raleigh, NC) |
Assignee: |
Consolidated Paper (Bahamas)
Limited (Montreal, Quebec, CA)
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Family
ID: |
27124212 |
Appl.
No.: |
04/885,201 |
Filed: |
December 15, 1969 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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817927 |
Apr 21, 1969 |
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Current U.S.
Class: |
428/110;
15/209.1; 156/291; 156/309.9; 428/138; 428/529; 604/366; 604/375;
428/292.7; 156/85; 156/306.6; 428/136; 428/212; 604/370 |
Current CPC
Class: |
D04H
13/00 (20130101); B32B 27/00 (20130101); Y10T
428/24314 (20150115); Y10T 428/3196 (20150401); Y10T
428/249926 (20150401); Y10T 428/24099 (20150115); Y10T
428/24942 (20150115); Y10T 428/24331 (20150115) |
Current International
Class: |
B32B
27/00 (20060101); D04H 13/00 (20060101); B32b
005/12 (); B32b 027/10 (); D04h 001/04 () |
Field of
Search: |
;161/55,57-60,140-143,146,148,156,79,82,84,85,64,402 ;264/146,147
;156/166,167,176-179,290,291,85,306,309 ;15/209 ;128/284 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Powell; William A.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of applicant's copending
application Ser. No. 817,927, now abandoned, in the United States.
Claims
We claim:
1. A reinforced laminate product comprising as essential layers
adhesively secured together:
a. a first layer of paper material;
b. at least a pair of reinforcing layers, the members of said pair
of layers being formed by fibrillated film webs of plastic material
having a plurality of substantially parallel extending and
substantially continuous filaments interconnected with adjacent
filaments of the same member at spaced locations, and at least two
of said members having their direction of fibrillation in an
angular direction to each other in said laminate; and
c. a second layer of paper material; wherein the tensile strength
of the laminate is provided essentially by said reinforcing layers
said reinforcing layers having an ultimate elongation substantially
matched with that of said paper material layers and said elongation
being up to between about 5 percent to 30 percent, and said
reinforcing layers being adhesively secured to said paper material
layers.
2. A product as defined in claim 1, wherein said filaments are
integrally interconnected by secondary filaments.
3. A product as defined in claim 2, wherein said filaments are
substantially rectangular in cross section with a high
width-to-thickness ratio.
4. A product as defined in claim 3, having a handle of up to 40
grams as measured on a Handle-O-Meter 34 lbs. per lineal inch, said
longitudinally extending filaments having a denier of up to
500.
5. A product as defined in claim 3, having a handle of up to 40
grams as measured on a Handle-O-Meter and a tensile strength of up
to 40 lbs. per lineal inch, said longitudinally extending filaments
having a denier of up to 500.
6. A product as claimed in claim 3, wherein said product has a
handle of less than 40 grams as measured on a Handle-O-Meter and a
tensile strength of 5-40 lbs. per lineal inch.
7. A product as claimed in claim 6, wherein said filaments have a
denier in the range of up to 500.
Description
BACKGROUND OF THE INVENTION
a. Field of the Invention
The present invention relates to nonwoven fabrics. More
particularly, the present invention relates to a nonwoven fabric
formed of cellulose based material and having a central reinforcing
layer formed by a fibrillated plastic web, said fabric having
handle and strength characteristics simulating those of woven
material.
B. Description of Prior Art
Many attempts have been made to produce nonwoven textile material
having the handle and strength characteristics of woven textiles.
As is well known, it is now relatively commonplace to hear of paper
dresses, paper diapers and a host of other products that heretofore
were primarily confined to woven webs.
Normally, such paper products are formed by either the wet laying
or dry laying process and are laminated from a plurality of such
webs secured together by suitable adhesive means. These nonwoven
fabrics do not possess the characteristics, particularly the handle
and tensile strength characteristics, that are sometimes
required.
Attempts to reinforce paper webs for use as simulated woven fabrics
by means of scrims of yarn or continuous monofilaments or even
sheet plastic material, have been made, but each such laminate has
its own inherent drawback. For example, scrim yarns which provide a
strong and flexible laminate also result in relatively coarse
texture to the material, and a relatively large percentage of the
total area of the product is not reinforced because of the spacing
between the yarn.
To applicant's knowledge, no low cost fabriclike material having a
high tensile strength and yet being very flexible and possessing
good handle and good texture is known.
SUMMARY OF INVENTION
It is thus the main object of the present invention to provide a
nonwoven textilelike material that is relatively strong, has good
handle and texture characteristics.
Broadly, the present invention comprises a first and second layer
of cellulosic material, a reinforcing web between said first and
second layer, said reinforcing web being formed of fibrillated
plastic material having a plurality of substantially parallel
fibers integrally interconnected at spaced points.
BRIEF DESCRIPTION OF DRAWINGS
Further features, objects and advantages of the present invention
will be evident from the following description taken in conjunction
with the accompanying drawing, in which:
The FIGURE is an exploded view illustrating a laminated product
constructed according to the present invention, the specific
product illustrated having a pair of fibrillated plastic film
webs.
DESCRIPTION OF PREFERRED EMBODIMENTS
The reinforced laminated product of the present invention as
illustrated in the FIGURE has a central reinforcing layer 3 formed
of a pair of fibrillated webs 5 and 7 of synthetic plastic film.
Each of these webs 5 and 7 has a plurality of substantially
parallel main filaments 9 interconnected to adjacent filaments 9 at
spaced locations 11 along its length either directly or by
secondary filaments. These secondary filaments are normally of the
same or smaller denier than the main filaments 9. The points or
locations 11 where the filaments are connected can be uniformly or
randomly spaced depending on the method of manufacture of such
fibrillated films. Thus, for some films these interconnections may
be widely spaced and for others they may be more numerous. But in
general these fibrillated films form a meshlike web of integrally
interconnected filaments.
In the illustrated arrangement, the reinforcing layer 3 shown has
two reinforcing layers 5 and 7 with the main filaments of one web 5
extending substantially perpendicular to the main filaments of the
other web 7 to provide equal reinforcing in the longitudinal and
transverse directions of the laminate. The webs 5 and 7 may be
adhesively bonded together, preferably at spaced locations, to form
a single reinforcing layer 3 before the cellulosic webs 15 and 17
are laminated to the reinforcing layer. While two webs 5 and 7 have
been shown to illustrate a laminated product having substantially
equal strength in both directions, it is apparent that only a
single web, i.e., either webs 5 or 7, may be the sole constituent
of the reinforcing layer 3.
Any number of reinforcing webs could be incorporated between the
two cellulosic layers. However, normally the number will never
exceed three when producing a simulated textile material.
Similarly, if desired, more than two cellulosic webs could be used,
but again, this will not normally be the case.
Also, when a pair of reinforcing layers 5 and 7 are used, they may
extend at 45.degree. to the longitudinal axis of the paper, rather
than one being substantially parallel and the other substantially
perpendicular to the said axis. In this manner, the main filaments
of the layers 5 and 7 would then extend at 90.degree. to each other
and 45.degree. to the longitudinal axis of the paper web.
In some cases, it may also be desirable to substitute for one of
the layers 5 or 7 or to provide an extra layer formed by spaced
elongated ribbons or strips of highly oriented plastic with the
strips having their longitudinal axis at an angle to the main
filaments of the fibrillated film. Preferably the strips would be
at an angle of 90.degree. to the main filaments of the fibrillated
film. However, angles of 45.degree. are also contemplated, for
example, a product could be made using fibrillated film extending
in the longitudinal direction of the web with two layers of ribbons
extending at 45.degree. to the main filaments of the fibrillated
film and the axis of the web and thus at 90.degree. to
themselves.
The central reinforcing web 5 or 7 comprises a fibrillated film
made from a suitable fibrillatable polymer which has the required
drape and strength characteristics. It has been found that
polyethylene and polypropylene, for example, all operate very
satisfactorily. Polyvinyl alcohol could be used where a disposable
product, such as diapers, is to be manufactured, since this
material can be made water dispersible.
The denier of the individual main filaments 9 of the fibrillated
film web can range from 1 to 500, i.e., up to 500. These filaments
and also the secondary filaments are characterized by having a
substantially rectangular cross section. The fibrillated
characteristic and the cross-sectional shape of the filaments
provide unexpected improvements in the handle of the laminated
product. Preferably, the cross section of the filaments is
rectangular with a high width to thickness ratio, and thus the
filaments lay substantially flat with their wide dimension in the
plane of the product thereby increasing the flexibility and
providing a laminated product having a smoother texture. For fine
fabrics the thickness should be as low as possible while being
consistent with the other properties of the product.
The fibrillated film used will be oriented to have an ultimate
elongation substantially matched with that of the paper webs to
which it is to be laminated. Thus, the ultimate elongation of the
fibrillated film will be in the range of 5 to 30 percent. This
matching is very important if the cellulose based material is to
remain relatively intact as one approaches the breaking strength of
the reinforcing layer.
The basis weight, or weight per unit area of each reinforcing
layer, depends on the strength required and on the tenacity of the
fibrillated film used. It can be easily calculated from the
following formula:
Basis Weight (oz./yd..sup.2) = 0.0575 T/t
where T is the desired tensile strength in lbs. per lineal inch and
t is the tenacity of the fibrillated film in grams per denier
(g.p.d.). It will be adjusted by spreading out the fibrillated
film.
Preferably, a fibrillated film formed of isotactic polypropylene
and having a tenacity as high as possible and normally in the range
of 3 to 4 grams per denier and a stretch of 7 to 30 percent,
preferably 7 to 9 percent and with the individual filaments, that
is main filaments, having a denier of 75 grams per 9,000 square
feet will be used.
Using present day methods of forming fibrillated film, lower denier
main filament films generally have lower tenacity. However, it is
believed that this will eventually be overcome by the film makers.
In any event, although a low denier polyethylene fibrillated film
gives superior handle characteristics, a stronger and cheaper
laminate is achieved when polypropylene of high tenacity and
greater denier is used and some of the handle characteristics are
sacrificed.
When making a laminated product of the type described flexibility
is an important characteristic. Using beam deflection analysis, it
can be shown that flexibility is inversely proportional to the cube
of the thickness and, therefore, a small decrease in thickness will
result in a considerable increase in flexibility and the thickness,
therefore, should be maintained at a minimum. It is also evident
that greatest flexibility is obtained when the modulus and width of
the individual filaments is kept to a minimum. However, this is an
impossible proposition since strength is also required, which means
a filament with a higher tenacity would be required and therefore a
compromise must be reached. Obviously, because of the rectangular
cross section of the individual main filaments, thickness is set by
the film, the width of the individual main filaments determines
their denier.
The tenacity figure presented herein for the fibrillated film was
obtained as follows. A sample of the film was cut and the ultimate
tensile strength in the filament direction was measured in lbs. The
sample was weighed and the weight required to obtain a sample of
9,000 meters length calculated, and this weight was divided into
the tensile strength to obtain the tenacity of the film.
For instance, by reinforcing two tissue grade papers of basis
weight 0.63 oz./yd..sup.2 with two cross-laid layers of fibrillated
polypropylene film of tenacity 3 g.p.d., each layer having a basis
weight of 0.24 oz./yd..sup.2, bonding the four layers with 0.15
oz./yd..sup.2 of adhesive applied by spraying, calendering the
laminate under 10 pounds per lineal inch, the following properties
were obtained:
Tensile strength lb./in. 15 Tear (Elmendorf) g. 700 Handle
(Handle-O-Meter) g. 30
A leading commercially available product formed by two layers of
tissue paper with a reinforcement formed from highly drafted fibers
secured therebetween by spots of adhesive was tested for
comparison. Such a product having a handle of about 30, i.e.,
equivalent to that of the instant invention, had a very low tensile
strength of 6 lbs. per inch and a low tear strength of 450 grams.
By comparison, the present invention provides a product with
equivalent handle, but with more than double the tensile strength
and almost double the tear strength.
The cellulosic webs 15 and 17 of the laminated product are
preferably made of tissue or toweling grade paper having a basis
weight in the range of about 8 to 20 lbs. per ream. However, in
some cases where heavier products are desired, such as bath mats or
towels, the paper may have a basis weight of up to about 50 lbs.
per ream.
Laminated products constructed in accordance with the present
invention can be manufactured to have a handle of less than 40
grams and preferably in the range of 15 to 40 grams as measured on
a Handle-O-Meter in accordance with Tappi Standard T498-su-66 and
yet maintain a tensile strength in the range of about 5 to 35 lbs.
per lineal inch. This means that one can now produce a nonwoven
fabric with a handle of less than 40 grams as measured on a
Handle-O-Meter and with a tensile strength of up to about 40 lbs.
per lineal inch. Furthermore, the resultant product has good
porosity, i.e., breathing characteristics, and has a relatively
smooth texture which is dependent primarily on the texture of the
cellulosic web forming the surface. Preferred products constructed
in accordance with the present invention will have a drape or
handle as measured on a Handle-O-Meter in the range of about 15 to
35 lbs. and a tensile strength of about 10 to 30 lbs. per lineal
inch and will be formed from paper webs having a basis weight in
the range of 8 to 10 lbs. per ream and a fibrillated film formed of
filaments having a tenacity of 1 g.p.d. or more.
As above indicated, any suitable adhesive may be used. It has been
found that with polyethylene or polypropylene as the fibrillated
film, BOSTIK SI- 1920, a water-based adhesive from USM Chemical Co.
Middleton, Mass. 01949, Jedbond, a water-based adhesive from Jedco
Chemical Corp., 601 North MacQuester Parkway, Mount Vernon, New
York 10552, and Hycar (P2100.times.20), a solvent-based adhesive
manufactured by B. F. Goodrich were very satisfactory. Normally, a
print-type bond will be used wherein the webs are adhered together
at spaced locations or the adhesive will be sprayed.
Another method of securing the fibrillated films to themselves and
to the paper webs would be to use a flame-laminating technique
wherein the surface of the film is heated by direct contact with
the flame and the films and paper layers are brought directly into
contact. Care should be taken of bringing to the melting point only
the surface of the fibrillated film, for example, by flame sealing
at high speed in the calender nip, to prevent the bulk of the film
from reaching the temperature at which it has been stretched and
annealed, in which case heavy shrinkage will occur. With such a
technique, the heat does not penetrate deeply into the film and
thus the orientation of the film is not appreciably reduced so that
a product having the desired characteristics can be obtained. This
flame-laminating technique is described in further detail in
applicant's copending Canadian application, Ser. No. 043,756, filed
Feb. 24, 1969.
In some cases, however, the above-mentioned latent shrinkage can be
used to obtain special effects. For instance, controlled heating of
the finished laminate under reduced tension will produce uniform
shrinkage which confers to the laminate a more pleasant texture and
a more textilelike appearance. In such cases, such shrinkage will
not exceed 10 percent and will preferably be between about 5 and 2
percent.
As indicated above, the central reinforcing layer may be formed of
one or more fibrillated webs. When a plurality of reinforcing webs
are to be used, they may be presecured together or secured to the
cellulose layers and then secured together. Cellulose fibers or
mixtures of cellulosic and synthetic fibers can be deposited onto
the adhesive-covered surface to produce a laminated reinforced
nonwoven web of the type contemplated. Such discrete fibers can be
deposited on the reinforcing layer by any suitable well-known
means, such as by flocking, air-laying or the like.
In laminating the reinforcing webs together, or pressing the
laminate together, when an adhesive is used, it is preferred to use
a heated nip at a pressure of up to about 50 lbs. per lineal inch.
When the cellulose layers pass through the nips, it is preferred to
use at least one rubber roll to provide the resilient nip.
One system of laminating is to use a pair of films, one having a
higher softening point than the other and heating the laminate as
it is pressed together so that the film with the lower melting
point is softened and functions as the adhesive to bond the film of
the higher melting point to the paper layers and/or to another
layer of higher melting point material. For example, a fibrillated
film of polyethylene and a fibrillated film of polypropylene may be
used as an adhesive and a reinforcing layer respectively, and the
laminate heated to a temperature above the softening temperature of
the polyethylene to soften same while squeezing the polyethylene
through the apertures in the polypropylene film thereby to bond the
polypropylene film to the paper liners. If desired, a layer of
polyethylene may be used between a pair of layers of polypropylene
to form a reinforcement or, alternatively, a layer of polypropylene
may be used with a single layer of polyethylene or with two layers
of polyethylene on opposite sides, or any combination thereof.
The adhesive or polyethylene layer is preferably fibrillated so
that its thickness may be correlated to that required and the main
filaments spread to uniformly distribute the adhesive in the
laminate, whereby an adhesive film of the required thickness to
penetrate through the spaces between the filaments of the
polypropylene films and bond the films and the paper layers
together is provided.
A solid sheet of polyethylene may in some cases be used. However,
generally, this will lead to waste of material as well as resulting
in a laminate of increased stiffness. Similarly, a perforated sheet
of polyethylene may be used but this generally would also lead to
increased stiffness and excess of adhesive. Thus, it is preferred
to use a fibrillated film as the adhesive layer if a two-component
film system as described above is to be used.
Where a two film system is used care must be taken to ensure that
the strength film (the polypropylene in the above example) does not
shrink unduly. Preferably, this strength film will have been
annealed at about the laminating temperature before laminating.
The improved laminated product is particularly suitable for use in
the manufacture of nonwoven material such as bedsheets, towels,
wiping cloths, bedclothes, wearing apparel, etc. Since the product
of the present invention provides a material having physical
characteristics of strength, handle and texture in particular, it
is well suited for these applications .
* * * * *