Laminated fibrous structure and method for manufacturing same

A laminated fibrous structure comprising at least two fibrous sheets and a method for manufacturing same are provided. At least one, and preferably two, of the fibrous sheets may be embossed. The sheets are movably joined together in a face-to-face relationship to form a laminated structure such that the sheets are able to move relative each other during the use of the laminated structure by a consumer, without tearing or separation of any one of the sheets comprising the laminated structure. The sheets comprising the laminated structure may be movably joined by using a bonding material, by mechanically engaging upstanding fibers created on the interfacing surfaces of the sheets, or by a combination of the bonding material and engaging the upstanding fibers.

FIELD OF THE INVENTION 
The present invention generally relates to laminated fibrous structures and 
to methods for manufacturing same. In particular, the present invention 
concerns a laminated structure comprising two or more laminae which are 
movable relative to each other without separation or tearing of either one 
of the laminae. 
BACKGROUND OF THE INVENTION 
Laminated fibrous structures and methods for their manufacturing are well 
known in the papermaking art. Laminated fibrous structures are created by 
a variety of ways, including embossing two or more individual fibrous 
sheets (also called plies or laminae) and adhesively joining them 
together. The resulting laminates have been employed for a variety of 
products ranging from packaging and construction materials to household 
paper products, such as paper tissues, table napkins, place mats, paper 
towels, and the like. 
To perform their intended tasks and to find wide acceptance, the household 
laminated paper products must exhibit certain physical characteristics. A 
typical consumer desires the household paper product to have a high 
quality cloth-like appearance, a relatively thick caliper, and an 
aesthetically pleasing pattern. All of these physical characteristics must 
be provided without sacrificing the other desired qualities of strength, 
softness, and absorbency of the paper product. 
Strength is the ability of a paper web to retain its physical integrity 
during use. 
Softness is the pleasing tactile sensation customers perceive when they 
crumple the paper in their hands and while using the paper for its 
intended purposes. 
Absorbency is the characteristic of the paper which allows it to take up 
and retain fluids, particularly--water and aqueous solutions and 
suspensions. In evaluating the absorbency of paper, not only is the 
absolute quantity of fluid a given amount of paper will hold significant, 
but the rate at which the paper will absorb the fluid is also important. 
In addition, when the paper is formed into a product such as a towel or 
wipe, the ability of the paper to cause a fluid to be taken up into the 
paper and thereby leave a dry wiped surface is also important. 
It is well known in the papermaking art that embossing generally increases 
absorbency, softness and bulk of the household paper products, such as 
toilet tissue, paper towel, napkins and the like. There are several common 
patterns of embossed laminated paper structure intended for the household 
products: nested (also known as "mated" or "male-female") pattern, 
knob-to-knob pattern, continuous pattern, and dual ply lamination. All 
these patterns are associated with the use of a pair of patterned, and 
axially parallel embossing rolls. During the process, the embossed sheets 
of paper are fed through a nip formed between two juxtaposed embossing 
rolls. Discrete protuberances or raised continuous surfaces on the 
embossing rolls compress regions of each sheet into engagement and 
contacting relationship with the opposing sheet according to a preselected 
pattern. The compressed regions of the sheets provide for joining of and 
maintaining the sheets in a face-to-face contacting relationship. 
Specifically, in a knob-to-knob pattern, the discrete protuberances (or 
"knobs") on one embossing roll are registered with the protuberances on 
the opposing embossing roll. In a nested pattern, the protuberances of one 
embossing roll mesh between the protuberances of the other embossing roll. 
In the continuous pattern, the raised continuous surfaces (as opposed to 
the discrete protuberances of the knob-to-knob pattern) of one of the 
embossing rolls are registered with the raised continuous surfaces of the 
other roll. The knob-to-knob pattern is described in the commonly assigned 
U.S. Pat. No. 3,414,459 issued to E. R. Wells on Dec. 3, 1968, which 
patent discloses the compressible paper structures formed by embossing 
identical raised patterns of discrete protuberances on two extensible 
paper sheets. The mated distal surfaces of the embossed protuberances are 
adhesively joined, and the resulting laminated paper structure is 
calendered. This patent is incorporated by reference herein. The dual ply 
lamination type is disclosed in the commonly assigned U.S. Pat. Nos. 
5,294,475, issued on Mar. 15, 1994 to McNeil and 5,468,323 issued on Nov. 
21, 1995 to McNeil, which patents are incorporated by reference herein. 
The McNeil patents disclose a dual ply laminate having two laminae which 
are embossed such that each embossed site of one lamina is adhesively 
joined to the non-embossed region of the other lamina. 
The examples of various patterns are illustrated in the prior art by U.S. 
Pat. No. 3,547,723, issued Dec. 15, 1970 to Gresham; U.S. Pat. No. 
3,556,907 issued on Jan. 19, 1971 to Nystrand; U.S. Pat. No. 3,708,366, 
issued Jan. 2, 1973 to Donnelly; U.S. Pat. No. 3,738,905, issued Jan. 12, 
1973 to Thomas; U.S. Pat. No. 3,867,225 issued Feb. 18, 1975 to Nystrand; 
U.S. Pat No. 4,483,728 issued Nov. 20, 1984 to Bauernfeind; U.S. Pat. No. 
4,921,034 issued May 1, 1990 to Burgess; U.S. Pat. No. 5,269,983 issued 
Dec. 14, 1993 to Schulz; U.S. Pat. No. 5,356,364, issued Oct. 18, 1995 to 
Veith et al.; U.S. Pat. No. 5,503,896 issued Apr. 2, 1996 to Veith et al.; 
and U.S. Pat. No. 5,529,563 issued Jun. 25, 1996 to Veith et al. The 
commonly assigned U.S. Pat. Des. No. 239,137 issued Mar. 9, 1976 to 
Appleman illustrates an embossing pattern found on commercially successful 
paper toweling. 
Different attempts have been made in the art to improve upon the 
embossments caused by the embossing process. For example, attempts have 
been made to provide embossed patterns having different depths, and 
asymmetric embossments. Other attempts have been made in the art to 
provide embossments having a certain size and representing a particular 
surface area of the embossed sheet. Yet other attempts in the art teach a 
particular angle, relative to the machine direction of manufacture, for 
the embossments. Still another attempts have been made in the art to 
provide embossments having particular configuration. Other attempts teach 
particular sizes of the protuberances and the corresponding recesses on 
the juxtaposed embossing rolls. Examples of the attempts to improve upon 
the embossments are illustrated in U.S. Pat. No. 4,320,162, issued Mar. 
16, 1982 to Schulz, et al; U.S. Pat. No. 4,659,608, issued Apr. 21, 1988 
to Schulz; U.S. Pat. No. 4,921,034 issued May 1, 1990 to Burgess et al; 
U.S. Pat. No. 3,940,529, issued Feb. 24, 1976 to Hepford, et. al; U.S. 
Pat. No. 4,325,773, issued Apr. 20, 1982 to Schulz; U.S. Pat. No. 
4,487,796, issued Dec. 11, 1984 to Lloyd et. al; and U.S. Pat. No. 
3,961,119, issued Jun. 1, 1976 to Thomas. 
Regardless of the particular type of embossing and pattern of lamination, 
paper laminates of the prior art are formed by rigidly binding two or more 
sheets of paper together to create a laminated structure. The individual 
sheets of a laminated structure of the prior art are joined in a number of 
ways, including both adhesive bonding and mechanical bonding. 
Lamination/embossing is known to be helpful to increase caliper of the 
laminated structure and compressibility normal to the plane of the 
laminated structure, and therefore--to increase the softness associated 
with the increased compressibility of the structure. An increase in 
caliper also generally improves the absorbency of the laminated product. 
At the same time, lamination/embossing of the prior art tends to reduce 
flexibility of the resulting laminated structure--because the adhesive or 
mechanical joining utilized by the prior art to bind two or more laminae 
together forms a rigid connection between the two or more laminae. The 
increase in caliper, while providing a higher compressibility and 
associated softness, decreases flexibility of the laminated structure of 
the prior art. In other words, a trade-off exists between the caliper and 
compressibility/softness of a laminated structure achieved by lamination 
and the flexibility of the laminated structure. 
Therefore, it is an object of the present invention to decouple the caliper 
and softness of a laminated structure from the flexibility of the 
laminated structure. 
It is another object of the present invention to produce a strong, soft and 
flexible laminated structure comprising two or more sheets which are 
movable relative to each other without separation or tearing of either one 
of these sheets. 
It is still another object of the present invention to provide a process 
for producing such a laminated structure. 
SUMMARY OF THE INVENTION 
In its product aspect, a laminated fibrous structure of the present 
invention comprises at least a first fibrous sheet and a second fibrous 
sheet. At least one of the first sheet and the second sheet may be 
embossed. The first sheet and the second sheet are joined together in a 
face-to-face relationship to form a laminated structure such that the 
first sheet and the second sheet are able to move (preferably laterally) 
relative each other during the use of the laminated structure by a 
consumer, without tearing or separation of any one of at least the first 
sheet and the second sheet comprising the laminated structure. The first 
sheet and the second sheet of the laminated structure may be movably 
joined together by a bonding material which allows relative movement 
between the first sheet and the second sheet. The first sheet and the 
second sheet may be movably joined together by creating areas of 
upstanding fibers on the first sheet and the second sheet, and then 
mechanically engaging the upstanding fibers on the first sheet with the 
corresponding upstanding fibers on the second sheet. The first sheet and 
the second sheet may be movably joined together by combining a bonding 
material and the upstanding fibers on one or both of the first sheet and 
the second sheet. 
In its process aspect, the present invention comprises the steps of 
providing at least two fibrous sheets and movably joining the sheets 
together such that the sheets of the resulting laminated structure are 
movable relative each other without tearing or separation of either one of 
the sheets. At least one of the sheets may be embossed. If the sheets are 
to be movably joined by a bonding material, the steps of providing and 
depositing a bonding material to at least one of the sheets must be 
performed. If the sheets are to be movably joined by mechanically engaging 
their respective upstanding fibers, the steps of creating portions of 
upstanding fibers on the sheets and engaging the upstanding fibers of one 
sheet with the upstanding fibers of the other sheet must be performed. If 
the sheets are to be movably joined by a combination of the bonding 
material and the upstanding fibers, the steps of providing and depositing 
the bonding material to at least one of the sheets, and the step of 
creating areas of upstanding fibers on at least one of the sheets must 
also be performed.

DETAILED DESCRIPTION OF THE INVENTION 
Laminated Fibrous Structure 
Referring to FIGS. 3A-4C, the present invention comprises a laminated 
fibrous structure 10, which herein may also be referred to as "laminated 
structure 10," or simply "structure 10." The fibers comprising the 
structure 10 of the present invention may be synthetic, such as polyolefin 
or polyester. Preferably, however, the fibers are cellulosic, such as 
cotton linters, rayon or bagasse, and more preferably are wood pulp, such 
as soft woods (gymnosperms and/or coniferous) and/or hard woods 
(angiosperms and/or deciduous). As used herein, the fibrous structure 10 
is considered "cellulosic" if the fibrous structure 10 comprises at least 
about 50% by weight or at least about 50% by volume cellulosic fibers, 
including, but not limited to, those fibers listed above. 
If wood pulp fibers are selected for the structure 10 of the present 
invention, the fibers may be produced by any pulping process, including 
chemical processes, such as sulfite, sulfite and soda processes, and 
mechanical processes, such as groundwood. Alternatively, the fibers may be 
produced by combinations of the mechanical and chemical processes, or may 
be recycled. The type, combination, and the processing of the fibers used 
are not critical to the present invention. 
The structure 10 of the present invention is macroscopically 
two-dimensional and planar, although not necessarily flat. The structure 
10 does have some thickness in the third dimension. However, the third 
dimension is relatively small compared to the actual first two dimensions 
or to the capability to manufacture a cellulosic structure 10 having 
relatively large measurements in the first two dimensions. 
The structure 10 of the present invention comprises two or more individual 
fibrous laminae or sheets. As used herein, the structure 10 comprising two 
sheets may also be referred to as a "two-ply" structure; the structure 10 
comprising three sheets may also be referred to as a "three-ply" 
structure, and so on. FIGS. 3A-3G show the structure 10 comprising a first 
fibrous sheet 11 and a second fibrous sheet 21. At least one of the first 
sheet 11 and the second sheet 21 may be embossed. FIG. 3H shows that 
neither the first sheet 11, nor the second sheet 21 may be embossed. 
Preferably, however, both the first sheet 11 and the second sheet 21 are 
embossed. FIGS. 3A-3F show the different embodiments of the structure 10 
comprising the first sheet 11 and the second sheet 21, both the first 
sheet 11 and the second sheet 21 being embossed. FIG. 3G shows the 
embodiment of the structure 10 comprising the first sheet 11 and the 
second sheet 21, with only the first sheet 11 being embossed. As used 
herein, the term "embossed" sheet refers to the sheet 11, or the sheet 21 
specially treated to have raised portions (or "embossments") 13, 23 
projecting generally outward from one of the surfaces of the sheet 11, 21, 
and usually produced by locally deflecting (or "embossing") portions of 
the otherwise plane sheet 11, 21 out of the plane of the sheet 11, 21. 
According to the present invention, the sheets 11 and 21 can be joined 
together by any one of the following methods: (1) connecting the sheets 11 
and 21 by using a bonding material 51, 52 which would allow the sheets 11 
and 21 to remain movable relative each other after the laminated structure 
10 has been created; (2) creating upstanding fibers 41 on the first sheet 
11 and upstanding fibers 42 on the second sheet 21, and then making the 
fibers 41 mechanically engage the fibers 42 such as to make the sheets 11 
and 21 to join each other and, at the same time, remain movable relative 
each other after the laminated structure 10 has been created; and (3) 
combining the method (1) and the method (2), i. e., creating the portions 
of the upstanding fibers 41 and/or 42 on one or both of the sheets 11 and 
21, and then joining the sheets 11 and 21 by using both the bonding 
material 51 and/or 52 and the upstanding fibers 41 and/or 42. It is 
believed that the bonding material 51 engaging the upstanding fibers 41 of 
the first sheet 11 and the surface fibers of the second sheet 21 will 
facilitate the movable connection of the first sheet 11 and the second 
sheet 21. 
As has been defined above, the embossments 13, 23 project generally 
outwardly from one of the surfaces of the sheet 11, 21. By the same token, 
the opposite surface of the paper sheet 11, 21 has depressions (or 
"debossments") corresponding to the embossments 13, 23. As used herein, 
each "embossment" has a corresponding "debossment," both terms indicating 
the same element 13, 23 viewed from the opposite sides of the same sheet 
11, 21, and designated--for this reason--by the same numerical reference: 
13 for the first sheet 11, and 23 for the second sheet 21. 
The embossments/debossments 13, 23 of the sheets 11, 21, respectively, are 
preferably arranged in a non-random repeating pattern corresponding to the 
embossing elements 63, 64 of the embossing rolls 61, 62, respectively 
(FIGS. 1A and 1B), utilized in the embossing process of the present 
invention and discussed herein below. By being "non-random," the 
embossments 13, 23 are considered to be disposed in a predictable pattern 
and may occur as a result of predetermined features of the manufacturing 
process. As used herein, the term "repeating" applies to a pattern which 
is formed more than once in the structure 10. By being "discrete," the 
adjacent embossments 13, 23 are not contiguous. According to the present 
invention, the embossments/debossments 13, 23 may comprise continuous 
surfaces forming a continuous pattern of an embossed laminated structure 
10. 
The rest of the sheets 11, 21 comprises essentially continuous non-embossed 
regions 15, 25 respectively, as shown in FIGS. 3A-4C and 5. As used 
herein, the "essentially continuous" non-embossed regions 15, 25 extend 
substantially throughout the structure 10 in both of its principal plan 
directions. Normally, the density of the essentially continuous 
non-embossed regions 15, 25 is less than the density of the embossments 
13, 23--because the non-embossed regions 15, 25 are normally not compacted 
in the embossing process. It will be apparent to one skilled in the art 
that there may be small transition regions bordering the embossments 13, 
23 and having a density intermediate the density of the embossments 13, 23 
and the density of the non-embossed regions 15, 25. Such transition 
regions are a normal and expected artifact of the manufacturing process 
and are not to be confused with either the embossments 13, 23 or the 
non-embossed regions 15, 25. 
If the structure 10 is to be used as a consumer product, such as a paper 
towel, a facial tissue, a toilet tissue, and the like, the non-embossed 
regions 15, 25 are preferably essentially continuous in two orthogonal 
directions within the plane of the structure 10. It is not necessary that 
such orthogonal directions be parallel and perpendicular the edges of the 
finished product or the direction of manufacture of the product (machine 
direction, or "MD"). It is preferred, however, that the tensile strength 
be imparted to the cellulosic structure 10 in two orthogonal directions, 
so that any applied tensile loading may be more readily accommodated 
without premature failure of the product due to such tensile loading. 
Preferably, at least one continuous direction is parallel to the direction 
of expected tensile loading of the finished product, according to the 
present invention. An example of the essentially continuous non-embossed 
regions 15 (associated with the first sheet 11) and 25 (associated with 
the second sheet 21) is illustrated in FIG. 5. Interruptions in the 
regions 15, 25 are tolerable, although not preferred, as long as such 
interruptions do not substantially adversely affect the material 
properties of the regions 15, 25 of the structure 10. 
As FIGS. 3A-3G show, the first sheet 11 and the second sheet 21 are joined 
together in a face-to-face relationship. If both the first sheet 11 and 
the second sheet 21 are embossed, the sheets 11 and 21 may be joined 
according to any one of the four general lamination patterns discussed in 
the "Background of the Invention" above. Different types and 
configurations of the embossments, which could be applied to the 
embossments 13, 23, could also be found in several patents referred to in 
the "Background of the Invention." As will be apparent from the following 
description of the present invention, the particular types and 
configurations of the embossments 13, 23 are not critical for the present 
invention. 
As used herein, the term "knob-to-knob" lamination refers to the type of 
patterns shown in FIGS. 3A, 3B, 4A, and 4C. In the knob-to-knob pattern, 
the first sheet 11 having the embossments 13 and the second sheet 21 
having the embossments 23 are joined at their respective embossments' 
distal surfaces, either directly (FIGS. 3A, 3B), or through a third sheet 
31 (FIG. 4A). FIG. 3A shows the first sheet 11 and the second sheet 21 
joined at the distal surfaces of their respective embossments 13 and 23 
which are aligned relative each other. It should be pointed out that the 
embossments 13 of the first sheet 11 need not be identical to the 
embossments 23 of the second sheet 21, nor need the embossments 13 be 
perfectly aligned with the embossments 23. FIG. 3B shows the first sheet 
11 and the second sheet 21 joined at the distal surfaces of their 
respective embossments 13 and 23 which are off-set relative each other. 
Also, the first sheet 11 and the second sheet 21 need not have the same 
properties, such--for example--as caliper and basis weight. The first 
sheet 11 and the second sheet 21 may be made from the different materials. 
Moreover, the structure 10 of the present invention may even comprise a 
heterogeneous laminated structure. By the term "heterogeneous laminated 
structure" it is meant that at least one of the individual sheets (for 
example, the first sheet 11) of the laminated structure 10 can be 
distinguished from at least one of the other individual sheets (for 
example, the second sheet 21) in terms of at least one such properties as 
caliper, macro-density, basis weight, texture, fiber furnish, etc. In a 
contrast, a "homogeneous laminated structure" is the structure 10 having 
the individual sheets 11, 21 which are made with substantially the same 
composition of material (fiber furnish and additives), and are all 
substantially identical to one another with respect to all of the above 
properties (i. e., for any of the above properties, the maximum sheet to 
sheet difference of the particular property is less than about 10% of the 
lower value of that property). 
FIGS. 4A, and 4C show the other embodiments of the structure 10 having the 
knob-to-knob pattern, and comprising three sheets 11, 21 and 31 in various 
combinations. One skilled in the art will readily understand that other 
permutations of the embodiments having the knob-to-knob pattern are 
possible and may be utilized in the present invention. 
As used herein, the term "nested" lamination refers to the patterns shown 
in FIGS. 3D, 3E, and 3F. As these figures show, and the term "nested" 
suggests, the first sheet 11 is joined to the second sheet 21 such that 
the embossments 13 ("male" elements) of the first sheet 11 are located, or 
"nested," in the corresponding debossments 23 ("female" elements) of the 
second sheet 21. Analogously to the knob-to-knob pattern discussed above, 
in the nested pattern, the embossments 13 of the first sheet 11 need not 
be identical to the debossments 23 of the second sheet 21, nor need the 
embossments 13 be perfectly aligned with the debossments 23. In the 
embodiments of the laminated structure 10 having the nested pattern and 
shown in FIGS. 3E and 3F, the first sheet 11 has its own included angle of 
embossment R1, and the second sheet 21 has its own included angle of 
embossment R2, different from the angle R1. In FIG. 3E, the included angle 
R1 of the embossment 13 of the first sheet 11 is greater than the included 
angle R2 of the embossment 23 of the second sheet 21. In FIG. 3F, the 
included angle R1 of the embossment 13 of the first sheet 11 is less than 
the included angle R2 of the embossment 23 of the second sheet 21. As used 
herein, the term "included angle of the embossment" refers to the angle 
formed by side walls 14, 24 of the embossment 13, 23 and a perpendicular 
to the plane of the paper sheet 11, 21, taken in a vertical cross-section, 
as shown in FIGS. 3E and 3F. As is the case with the knob-to-knob pattern 
described hereabove, a third paper sheet can be joined to one of the first 
sheet 11 and second sheet 21 connected in the nested pattern. 
FIG. 3C shows another embodiment of the paper structure of the present 
invention, having a dual ply lamination pattern. As has been noted above, 
the dual ply lamination is described in the commonly assigned U.S. Pat. 
No. 5,468,323, issued Nov. 21, 1995 to McNeil, which patent is 
incorporated by reference herein. As FIG. 3C shows, the embossments 13 of 
the first sheet 11 are joined to the non-embossed regions 25 of the second 
sheet 21, and the embossments 23 of the second sheet 21 are joined to the 
non-embossed regions 15 of the first sheet 11. 
In the laminated paper structures of the prior art, laminae are rigidly 
joined together (usually, by an adhesive or mechanically, or by a 
combination thereof) such that during the use of the laminated structure, 
the relative movement of the individual sheets forming the laminated 
structure is not possible without tearing or separation of the individual 
sheet. Therefore, during the use, when the laminated structure is 
naturally subjected to bending, rumpling, creasing, and so on, the rigid 
connection of the individual sheets comprising the laminates of the prior 
art affects the flexibility of these laminates. FIG. 2A schematically 
shows a fragment of a two-ply laminated structure 100 of the prior art. 
The structure 100 comprises a sheet 111 and a sheet 121, the sheets 111 
and 121 being rigidly interconnected. The structure 100 is bent such that 
the sheet 111 is curved outwardly and the sheet 121 is curved inwardly. 
The sheet 111 is in tension, and the sheet 121 is in compression. In FIG. 
2A, a dashed line a-b represents an average length of a curvature of the 
sheet 111 formed by bending the laminate 100 of the prior art between two 
pairs of corresponding embossments 113 and 123. Analogously, a dashed line 
c-d represents an average length of a curvature of the sheet 121 formed by 
bending the laminate 100 between the same two pairs of the corresponding 
embossments 113 and 123. The point "a" must radially correspond to the 
point "c," and the point "b" must radially correspond to the point "d" 
--because of the rigid connection between the sheets 111 and 121 at the 
points a-c and b-d. One skilled in the art will readily understand that 
the length of the curvature c-d associated with the sheet 121 must be less 
than the length of the curvature a-b associated with the sheet 111. 
Therefore, when the laminate 100 becomes bent as shown in FIG. 2A, a sheet 
121 must foreshorten more extensively relative the sheet 111--to 
accommodate the smaller length of the curvature c-d associated with the 
sheet 121. Otherwise, the integrity of one of the sheets 111 and 121 or 
their connection may be violated (not shown). Not intending to be limited 
by theory, the applicant believes that the resistance to rumpling (which 
may include both bending and buckling) of the sheet 121 affects the 
flexibility of the laminate 100 of the prior art. 
In sharp contrast with the prior art, the individual sheets 11, 21 of the 
laminated structure 10 of the present invention are able to move relative 
to each other during the use of the structure 10 by a consumer, without 
tearing of either the first sheet 11 or the second sheet 21, or separation 
of the first sheet 11 from the second sheet 21. The ability of the 
individual sheets 11, 21 which form the laminated structure 10 to move 
relative each other is accomplished by providing a non-rigid, flexible 
connection between the sheets 11, 21. Preferably, the sheets 11, 21 are 
laterally movable relative each other, as FIG. 2B shows. The laminated 
structure 10 is bent such that the sheet 11 is curved outwardly and the 
sheet 21 is curved inwardly. In FIG. 2B, a dashed line a1-b1 represents an 
average length of a curvature of the sheet 11 formed by bending the 
structure 10 of the present invention between two pairs of the 
corresponding embossments 13 and 23. A dashed line c1-d1 represents an 
average length of a curvature of the sheet 21 formed by bending the 
laminate 10 between the same pair of the corresponding embossments 13 and 
23. Due to the movable connection (created, for example, by the use of the 
bonding material 51) between the sheets 11 and 21, the embossments 23 of 
the sheet 21 can laterally move relative the corresponding embossments 13 
of the sheet 11. As could be seen in FIG. 2B, due to the movable 
connection between the sheets 11 and 21, the sheet 21 need not foreshorten 
to accommodate the bending of the structure 10--because now the curvature 
a1-b1 associated with the sheet 11 can retain essentially the same length 
as the length of the curvature c1-d1 associated with the sheet 21. Thus, 
the movable connection between the sheets 11 and 12 minimizes excessive 
tension and/or compression of the sheets 11 and 12. 
In one embodiment, shown in FIG. 3A, the first sheet 11 and the second 
sheet 21 of the laminated structure 10 of the present invention are joined 
together by a first bonding material 51 which allows relative movement of 
the sheets 11 and 21. If desired, a second bonding material 52, different 
from the first bonding material 51, may be used in the laminated structure 
10 of the present invention. For example, as shown in FIG. 4C, in the 
laminated structure 10 comprising three (or more) sheets 11, 21, 31, a 
second bonding material 52 is used to connect the third sheet 31 to one of 
the first sheet 11 and the second sheet 21. Of course, the same bonding 
material (either the first bonding material 51 or the second bonding 
material 52) may be used to join the sheets 11, 21, 31 together. Also, two 
or more different bonding materials 51, 52 may be used, if desired, to 
join the first sheet 11 and the second sheet 21. 
In another embodiment of the present invention, shown in FIG. 3B, at least 
one of the first sheet 11 and the second sheet 21, for example the first 
sheet 11, has upstanding fibers 41 on one of its surfaces. These 
upstanding fibers 41 can be integral with the first sheet 11 and formed by 
brushing the predetermined areas of the surface of the first sheet 11. 
Alternatively, the fibers 41 can be discretely attached to the surface of 
the first sheet 11 in the predetermined areas. It is believed that the 
upstanding fibers 41, when combined with the bonding material 51, 52, will 
facilitate the process of joining the first sheet 11 and the second sheet 
21 and afford the sheets 11 and 21 relative mobility when the resulting 
laminated structure 10 is formed. 
In another embodiment shown in FIG. 6, the first sheet 11 has the portions 
of the upstanding fibers 41, and the second sheet 21 have the portions of 
the upstanding fibers 42, which portions are located in the mutually 
corresponding surface areas of the first sheet 11 and the second sheet 21, 
respectively, such that when the first sheet 11 and the second sheet 21 
are being joined together, their respective portions of the upstanding 
fibers 41 and 42 generally coincide. In the latter case, the first sheet 
11 and the second sheet 21 may be joined by their respective upstanding 
fibers 41, 42 and without the use of the bonding material 51, 52, as shown 
in FIG. 6. As FIG. 6 shows, the upstanding fibers 41 of the first sheet 11 
mechanically engage the upstanding fibers 42 of the second sheet 21. 
Without being limited by theory, the applicant believes that the laminated 
structure 10 of the present invention formed by the individual sheets 11, 
21 movably joined together possesses higher flexibility and increased 
caliper, and may provide the improved absorbency--compared to the 
laminated structures of the prior art formed by the individual sheets 
rigidly joined together but otherwise having substantially the same 
properties as the individual sheets 11, 21 forming the structure 10 of the 
present invention. 
Process for Manufacturing Laminated Fibrous Structure 
FIGS. 1A and 1B schematically show an apparatus utilized in a process of 
the present invention. Referring to FIG. 1A, two fibrous sheets 11 and 21 
are fed into nips E1 and E2 formed by embossing rolls 61 and 62 and 
resilient pressure rolls 71 and 72, respectively. The sheets 11, 21 are 
preferably, but not necessarily, extensible. The embossing rolls 61 and 62 
are made of a substantially rigid material, such as steel, and are 
provided with embossing patterns. The pressure rolls 71 and 72 are made of 
a flexible and resilient material, such as rubber. The embossing rolls 61, 
62 are juxtaposedly mounted for cooperative rotation by suitable drive 
means about their respective parallel axes. The embossing rolls 61, 62 
form a marrying nip N therebetween. The pressure rolls 71, 72 are mounted 
for rotation by any suitable drive means about their respective parallel 
axes, and are cooperatively disposed in juxtaposed positions relative the 
embossing rolls 61, 62, respectively, to form the embossing nips E1 and E2 
therebetween. The sheets 11 and 21 are forwarded through the nips E1 and 
E2 and are embossed by passing through the nips E1, E2. While the 
embossing of either one or both of the individual sheets 11, 21 by passing 
them through the nips E1, E2, respectively, is preferred, any embossing 
method is satisfactory for use in the process of the present invention. 
After the embossed patterns of discrete embossments 13, 23 are formed on 
the sheets 11, 21 by the action of the nips E1, E2, respectively, the 
sheets 11, 21 remain in arcuate contact with the embossing pattern on the 
embossing rolls 61, 62, respectively, as the embossing rolls 61, 62 
rotate. The embossing rolls 61, 62 are rotatably driven at surface 
velocities V1 and V2, respectively. Preferably, the surface velocity V1 of 
the embossing roll 61 is equal to the surface velocity V2 of the embossing 
roll 62. The methods of tension control and speed adjustment are well 
known in the art and are not critical for the present invention. 
As has been discussed above, the sheets 11 and 21 can be joined together by 
any one of the following methods: (1) connecting the sheets 11 and 21 by 
using a bonding material which would allow the sheets 11 and 21 to remain 
movable relative each other after the laminated structure 10 has been 
created; (2) creating upstanding fibers 41 on the first sheet 11 and 
upstanding fibers 42 on the second sheet 21, and then making the fibers 41 
mechanically engage the fibers 42 such as to make the sheets 11 and 21 to 
join each other and, at the same time, remain movable relative each other 
after the laminated structure 10 has been created; and (3) combining the 
method (1) and the method (2), i. e., creating the portions of the 
upstanding fibers 41 and/or 42 on one or both of the sheets 11 and 21, and 
then joining the sheets 11 and 21 by using both the bonding material 51 
and/or 52 and the upstanding fibers 41 and/or 42. 
Joining Sheets by Using Bonding Material 
As FIGS. 1A and 1B show, the first sheet 11 and the second sheet 21, after 
having passed the embossing nips E1, E2 formed by the embossing rolls 61, 
62 and the pressure rolls 71, 72, respectively, are in the arcuate contact 
with the rotating embossing rolls 61 and 62, respectively. Then, the 
bonding material 51 is deposited on the first sheet 11. Alternatively, the 
bonding material 52 may be deposited on the second embossing roll 62. If 
desired, both the bonding material 51 and the bonding material 52 may be 
deposited on both the paper web associated with the embossing roll 61 and 
the paper web associated with the embossing roll 62, respectively. As has 
been pointed out above, the first bonding material 51 may be identical to 
the second bonding material 52. The first and second bonding material 51, 
52 may comprise polyurethane latex or thermosetting adhesive. Foam may 
also be utilized as the bonding material 51, 52. 
If either one or both the first sheet 11 and the second sheet 21 are 
embossed, the bonding material 51, 52 is preferably deposited on the 
distal surfaces of the embossings 13 on the first sheet 11 and/or 
embossings 23 on the second sheet 21. The method of depositing the bonding 
material on the sheets 11, 21 is not critical for the present invention. 
In FIGS. 1A and 1B, the device for depositing the bonding material 51, 52 
is schematically shown as two pairs of applicator rolls 91, 92 juxtaposed 
in axially parallel relationship with the embossing rolls 61, 62, 
respectively, but it should be understood that other suitable methods of 
depositing the bonding material 51, 52 may be utilized in the process. 
As FIG. 1A shows, after the bonding material 51 and/or 52 has been 
deposited on one or both of the first sheet 11 and the second sheet 21, 
the first sheet 11 and the second sheet 21 are forwarded to the marrying 
nip N, where they will be movably joined in a face-to-face relationship to 
form the laminated structure 10 of the present invention. 
If the resulting laminated structure 10 is to have the knob-to-knob pattern 
of lamination (which has been discussed hereinabove), the embossing rolls 
61 and 62 are registered such that the first sheet 11 and the second sheet 
21 are joined at the distal surfaces of at least some of their respective, 
and preferably registered, embossments 13 and 23. If the resulting 
laminated structure 10 is to have the nested pattern of lamination (which 
has also been discussed herein above), the embossing rolls 61 and 62 are 
registered such that the embossments 13 on the first sheet 11 may be 
joined to the debossments 23 of the sheet 21 as shown in one of FIGS. 3D, 
3E, and 3F. If the resulting laminated structure 10 is to have the dual 
ply lamination pattern (which has also been discussed hereinabove), the 
embossing rolls 61 and 62 are registered such that the embossments 13 on 
the first sheet 11 may be joined to the non-embossed areas 25 of the 
second sheet 21, and the embossments 23 of the second sheet 21 may be 
joined to the non-embossed areas 15 of the first sheet, as shown in FIG. 
3C. 
If desired, a third sheet 31 may be interposed between the first sheet 11 
and the second sheet 21 to form a three-ply laminated structure 10, as 
shown in FIG. 1B. Although FIG. 1B shows the third sheet 31 as a 
non-embossed sheet, the embossed third sheet 31 (not shown) may also be 
utilized in the present invention. 
Joining Sheets by Engaging Their Upstanding Fibers 
While the sheets 11, 21 are in arcuate contact with the rolls 61 and 62, 
portions of upstanding fibers 41 associated with the first sheet 11 and/or 
portions of upstanding fibers 42 associated with the second sheet 21 are 
created on the respective sheets 11, 21. The upstanding fibers 41 and 42 
may be created by any method known in the art. For example, integral 
upstanding fibers 41, 42 may be created by brushing the embossed areas of 
the sheets 11, 21 using brushing rolls 81, 82, as shown in FIG. 1. As used 
herein, the upstanding fibers 41, 42 are integral with the sheets 11, 21, 
respectively, if the upstanding fibers 41, 42 are inherent elements of the 
sheets 11, 21, respectively. Alternatively, the upstanding fibers 41, 42 
may be discretely attached to the sheets 11, 21. The discretely attached 
fibers 41, 42 may comprise a material different from the material of the 
sheets 11, 21. 
After the upstanding fibers 41, 42 have been created, the first sheet 11 
and the second sheet 21 are forwarded to the nip N to be joined in a 
face-to-face relationship such that the upstanding fibers 41 of the first 
sheet 11 face the upstanding fibers 42 of the second sheet 21. By passing 
through the nip N, the upstanding fibers 41 of the first sheet 11 
mechanically engage the upstanding fibers 42 of the second sheet 21, thus 
movably joining the first sheet 11 and the second sheet 21 together such 
that the first sheet 11 and the second sheet 21 are movable relative each 
other without tearing or separation of either the first sheet 11 or the 
second sheet 21. 
Joining Sheets by Using Upstanding Fibers and Bonding Material 
At least one of the first sheet 11 and the second sheet 21 may be treated 
to create the upstanding fibers 41 or 42, respectively. Of course, the 
upstanding fibers 41, 42 may be created on both the first sheet 11 and the 
second sheet 21. For example, the first sheet 11 is treated to have the 
portions of upstanding fibers 41. Then, the bonding material 51 may be 
deposited directly on the portions of the upstanding fibers 41, and 
preferably to the free ends of the upstanding fibers 41. 
Alternatively, the bonding material 52 may be deposited on the second sheet 
21 which has no upstanding fibers. In the latter case, the bonding 
material 52 is preferably deposited in the areas that will correspond to 
the portions of the upstanding fibers 41 on the first sheet 11 when the 
first sheet 11 and the second sheet 21 are disposed in a face-to-face 
relationship in the nip N. Thus, the upstanding fibers 41 of the first 
sheet 11 engage the bonding material 52 deposited on the second sheet 21 
to movably join the first sheet 11 and the second sheet 21 to form the 
laminated structure 10 of the present invention such that the first sheet 
11 and the second sheet 21 are movable relative each other without tearing 
of either the first sheet or the second sheet or separation of the first 
sheet from the second sheet.