Abstract:
A moisture resistant film is for covering an architectural structure. The film includes a flexible membrane defining a plane and a first plurality of spaced apart, discrete embossings formed in the membrane extending outwardly of the plane. The embossings are formed in rows in an x-direction and in columns in a y-direction. The rows are parallel to and spaced from one another and the columns are parallel to and spaced from one another. A method and tool for making the film are also disclosed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to an embossed cross-laminated film or sheet construction. More particularly, the present invention relates to a sheet formed from a laminate of two cross-oriented films that is embossed to form a three-dimensional engineered surface material for use as a construction moisture barrier.  
         [0002]     In the construction of buildings such as houses and the like, moisture and air barriers are used between the house framing and the outer covering, e.g., siding or clapboard. These barriers are used to prevent the intrusion of moisture into the areas of the building between the framing or inner walls and the outer house covering.  
         [0003]     Moisture ingress between the outer covering and the framing or walls of a house can be problematic. For example, molds and fungus have been linked to the presence of water in certain areas of buildings. As such, there have been considerable efforts made to create barriers that not only prevent the ingress or intrusion of water (as bulk water and moisture or condensate) but also direct such water away from the interior walls to enhance drainage, prevent pooling and to reduce the opportunity for mold and fungus growth.  
         [0004]     Barrier materials, also referred to as “house-wraps”, are installed between frame sheathing surfaces and exterior covering or cladding products to provide a secondary layer of protection from moisture intrusion. This weather resistive barrier function can be further enhanced to promote drainage of moisture and the flow of air, to reduce the likelihood that water will penetrate further into the wall assembly where wetting of the substrate and framing materials could likely occur. Elevated moisture levels in these areas could contribute to mold growth and/or wood decay and ultimately increase the potential for structural failure.  
         [0005]     Recently, house-wrap barrier materials have been developed that include drip channels or drainage channels to promote moisture drainage. However, these channels are direction dependent. That is, because of the geometry of the material and the geometry and “shape” of the channels formed in the material, in order for the material to function properly (that is, to drain properly), the material must be installed in a certain orientation or direction on the structure or building. In the event that the material is improperly installed, liquid can continue to pool and moisture or liquid intrusion can occur.  
         [0006]     Moreover, known house-wrap materials are formed from woven materials. These materials tend to impart high tear resistance, which is highly desirable in the construction industry. However, such materials can be expensive to manufacture and are typically more permeable (to liquid water as opposed to water vapor) than non-woven materials.  
         [0007]     Accordingly, there is a need for a house-wrap material having a high level of moisture resistance. Desirably, such a material has structure that permits it to direct water away from the interior regions of the structure to which it is installed. More desirably, such a material functions independent of the orientation at which it is installed on the structure. Most desirably, such a material has a high tear resistance and high overall strength to permit use in a wide variety of construction situations and at a wide variety of sites.  
       SUMMARY OF THE INVENTION  
       [0008]     A moisture resistant house-wrap film is configured for covering an architectural structure. The house-wrap is formed from a flexible membrane defining a plane having a first plurality of spaced apart, discrete embossings formed in the membrane extending outwardly of the plane. The embossings are formed in rows in a (general) x-direction and in columns in a (general) y-direction. Preferably, a plurality of rows and a plurality of columns are formed. The rows are spaced from one another and the columns are spaced from one another. In a most preferred house-wrap, the rows and columns are non-rectilinear.  
         [0009]     Such a house-wrap material has a high level of moisture resistance in combination with structure that permits it to direct water away from the interior regions of the structure to which it is installed. Such a material functions independent of the orientation at which it is installed on the structure and has a high tear resistance and high overall strength to permit use in a wide variety of construction situations and at a wide variety of sites.  
         [0010]     In a preferred house-wrap, the rows are formed in parallel curved patterns and the columns are formed in parallel curved patterns. Most preferably, the curves (in both the x- and y-directions) are sine wave patterns. A present house-wrap has the first plurality of spaced apart discrete embossings formed transverse to the plane in a first direction and a second plurality of spaced apart, discrete embossings formed in the membrane extending outwardly of the plane in a second direction opposite of the first direction. The embossings are formed in rows in the x-direction and in columns in the y-direction. The rows and columns are non-rectilinear. In such a pattern, the rows and columns of the first plurality of embossings are spaced from one another by rows and columns of the second plurality of embossings. Non-embossed neutral spaces are disposed between each of the first plurality of spaced apart discrete embossings and between each of the second plurality of spaced apart discrete embossings. A present embossing has a truncated, pyramidal parallelogram shape.  
         [0011]     A preferred film has the flexible membrane formed as a multi-layer lamination having a first oriented plastic layer and a second oriented plastic layer. The oriented plastic layers cross at an angle between but not equal to zero degrees and 180 degrees relative to one another. Preferably the layers are at an angle between 40 degrees and 140 degrees relative to the orientation of the other plastic layer; and most preferably, the layers are at an angle of orientation of about 90 degrees to one another.  
         [0012]     Such a membrane has first and second plastic layers that are polyolefins, and preferably polyethylene. A bonding media can be disposed between the plastic layers.  
         [0013]     A method of forming the moisture resistant flexible film includes the steps of laminating a first oriented plastic layer and a second oriented plastic layer to one another where the orientations of the first and second layers cross at an angle between but not equal to zero degrees and 180 degrees to form a flexible membrane defining a plane. The method includes forming in the flexible membrane a first plurality of spaced apart, discrete embossings extending outwardly of the plane. The embossings are formed in rows in an x-direction and in columns in a y-direction. In a preferred method, the rows and columns are non-rectilinear.  
         [0014]     In a preferred method, in the forming step, the first plurality of spaced apart discrete embossings are formed transverse to the plane in a first direction and a second plurality of spaced apart, discrete embossings are formed in the membrane extending outwardly of the plane in a second direction opposite of the first direction. In such a method, the embossings are formed in rows in an x-direction and in columns in a y-direction. Preferably, the rows and columns are non-rectilinear, and the rows and columns of the first plurality of embossings are spaced from one another by rows and columns of the second plurality of embossings.  
         [0015]     A tool for forming the embossings includes a roller having a plurality of embossing projections extending therefrom defining alternating first rows of alternating first direction embossing projections and neutral spaces and intermediate alternating second rows of second direction embossing projections (which second direction embossings are actually cavities) and neutral spaces. The alternating first rows of first direction embossing projections and neutral spaces are disposed to form alternating first columns of first direction embossing projections and neutral spaces and the intermediate alternating second rows of second direction embossing cavities and neutral spaces are disposed to form alternating second columns of second direction embossing cavities and neutral spaces. In a present tool, the first rows of first direction embossing projections and neutral spaces and second rows of second direction embossing cavities and neutral spaces are non-rectilinear and are parallel to one another and the first columns of first direction embossing projections and neutral spaces and second columns of second direction embossing cavities and neutral spaces are non-rectilinear and are parallel to one another. A present tool has a second mating roller having a mating profile.  
         [0016]     These and other features and advantages of the present invention will be readily apparent from the following detailed description, in conjunction with the claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein:  
         [0018]      FIG. 1  is a perspective illustration of a tool (a pair of rollers), embodying one aspect of the present invention, for forming an embossed cross-laminated house-wrap film also of the present invention;  
         [0019]      FIG. 2  illustrates, schematically, the formation of the tool embossing element locations;  
         [0020]      FIG. 3  illustrates the position, pattern and formation of the embossing elements of the tool;  
         [0021]      FIG. 4  illustrates one embodiment of the film as formed having a double sine wave embossing pattern formed therein;  
         [0022]      FIG. 5  is an enlarged illustration of the film of  FIG. 4 ;  
         [0023]      FIG. 6  is an enlarged view of the film of  FIG. 5 ;  
         [0024]      FIG. 7  illustrates sections of the embossing tool used to produce the film shown in  FIGS. 5 and 6 ;  
         [0025]      FIG. 8  illustrates a portion of the film sheet;  
         [0026]      FIG. 9  is a cross-section of the sheet taken along line  9 - 9  of  FIG. 8 ;  
         [0027]      FIG. 10  is a cross-section of the sheet taken along line  10 - 10  of  FIG. 8 ;  
         [0028]      FIG. 11  is a schematic illustration of a building having the embossed cross-laminated house-wrap film installed thereon;  
         [0029]      FIG. 12  is a schematic illustration of a process for forming the house-wrap film;  
         [0030]      FIG. 13  is an enlarged view of a portion of an alternate tool for forming an alternate embossing in the film;  
         [0031]      FIG. 14  is a cross-section of the alternate film;  
         [0032]      FIG. 15  is a view of the top or bottom surface of the alternate film; and  
         [0033]      FIG. 16  is an exploded perspective view of a the multi-layer lamination used in the film of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0034]     While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated.  
         [0035]     It should be understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein.  
         [0036]     Referring now to the figures and briefly, to  FIG. 8 , there is shown one embodiment of an embossed, cross-laminated film  10 , or house-wrap embodying the principles of the present invention. The house-wrap film  10  is shown positioned on a building B in  FIG. 11 . The house-wrap material  10  has a high level of moisture resistance and, as is described below, has a structure or engineered surface that permits it to channel water away from the interface of the material and the structure to which it is installed.  
         [0037]     The house-wrap material  10  has an engineered surface that provides both a stand-off effect which precludes pooling or ponding, for example, along a ridge formed where house siding rests on the underlying house structure, and orientation independent channels  12  (see  FIG. 8 ) to permit moisture (e.g., water) to drain from the surface of the wrap  10 .  
         [0038]     The wrap material  10  is preferably a cross-laminate of uniaxially oriented films from crystalline polymers. Such materials are known to exhibit a number of beneficial properties including improved tear resistance. One example of a multi-layer, oriented or “bias-cut” plastic film is disclosed in Barnes et al., U.S. Pat. No. 6,284,344, which is commonly assigned with the present invention and which is incorporated herein by reference.  
         [0039]     A preferred material is VALERON® brand film commercially available from ITW VALERON® of Houston, Texas. Referring to  FIG. 16 , the film  14  (also referred to as a web) is a polyolefin, preferably a high density polyethylene (HDPE) material that is formed from a cross-laminate of two film layers  16 ,  18  that are each extruded and bias cut in a continuous spiral to obtain molecular orientation at an angle to a roller onto which the film is collected. The bias cut films  16 ,  18  are then cross-laminated, preferably with an adhesive or polymer  20  between the film layers  16 ,  18  to form the web  14 . Other non-woven materials, such as polyethylene terephthalate (PET), and coextruded polymeric materials are contemplated for use in the embossed house-wrap film.  
         [0040]     As seen in  FIG. 16 , the direction of orientation of the first film layer  16  crosses the direction of orientation of the second film layer  18  at a predetermined angle a such that the orientations of the layers  16 ,  18  are non-parallel. That is, the film layer orientations cross one another at an angle a between but not equal to zero degrees and 180 degrees. As seen in  FIG. 16 , the orientation of layer  16  is indicated by the lines at  22  and the orientation of layer  18  is indicated by the lines at  24 . The angle α can range from about 40 degrees to about 140 degrees, and preferably ranges from about 78 degrees to about 104 degrees. A most preferred orientation angle is about 90 degrees so that the films  16 ,  18  are oriented perpendicular to one another. A preferred laminate web  14  has a thickness of about 3.2 thousandths of an inch (0.0032 inches or 3.2 mils) to about 4.0 mils. The web  14  can, of course be formed having other thicknesses, depending upon the desired application; however, it has been found that these web gauges or thicknesses function well for conventional residential construction.  
         [0041]     Following cross-lamination, the web  14  has an engineered surface formed therein. A present surface is formed by embossing the web  14  to form the film  10 . Embossings are formed in each direction of the web  14  relative to the plane P 10  of the film  10 . That is, relative to the plane P 10  of the film  10  (being the plane of the drawing of  FIGS. 5 and 8 ), the embossings are formed out of the plane of the paper (for purposes of discussion, this is referred to as a positive embossing  30 ) and into the plane of the paper (a negative embossing  34 ). When viewing the surface of the web  10 , the embossings define positive embossings  30  and negative embossings  34  having a neutral region  32  for those areas that are not embossed. The embossings  30 ,  34  are formed in the z-direction of the film  10 . It will be appreciated by those skilled in the art that what is viewed as a positive embossing  30  on one “side” of the film  10  is a negative embossing  34  on the other side of the film  10 .  
         [0042]     The embossings  30 ,  34  are configured in predetermined patterns in both the x-direction (or rows, indicated generally at  26 ) and the y-direction (or columns, indicated generally at  28 ) of the film  10 . In a present film  10 , neither the rows  26  nor the columns  28  are straight. Rather, as illustrated, the rows  26  and columns  28  are formed from discrete embossed  30 ,  34  elements disposed, as discussed below, in sine wave patterns. Each row  26  and each column  28  is formed from alternating positive embossings  30  and neutral plane regions or areas  32  or negative embossings  34  and neutral plane areas  32 , with the rows  26  (or columns  28 ) staggered so that each region (that is, each embossing  30 ,  34  or each neutral area  32 ) is adjacent an unlike region. That is, because half of the regions in each row  26  and in each column  28  are neutral areas  32 , the rows  26  (and columns  28 ) are formed relative to one another such that the neutral areas  32  do not share a common edge, but are staggered relative to one another (touching at their respective corners).  
         [0043]     For example, referring to  FIG. 8 , the positive embossings of row RA (embossings RA 1 -RA 10 ) are spaced from adjacent positive embossings in that row (that is, RA 1  is spaced from RA 2 , which is spaced from RA 3 , and so on) by the neutral spaces RAS 1 , RAS 2 , RAS 3 , and so on. And, the positive embossings of row RA are spaced from the positive embossings of row RC by the neutral plane areas CAS 1 , CCS 1  and so on. The same pattern is followed for the columns. That is, the positive embossings of column CA (embossings CA 1 -CA 10 ) are spaced from adjacent positive embossings in that column (that is, CA 1  is spaced from CA 2 , which is spaced from CA 3 , and so on) by the neutral spaces CAS 1 , CAS 2 , CAS 3 , and so on. And, the positive embossings of column CA are spaced from the positive embossings of column CC by the neutral plane areas CBS 1 , CBS 2  and so on. As shown, the film  10  has at least two rows R (e.g., RA, RB, RC) and at least two columns C (e.g., CA, CB, CC). It will be appreciated from the figures that the present film  10  is formed having a checkerboard-like appearance, with about 25 percent of the “spaces” being positive embossings, about 25 percent of the “spaces” being negative embossings, and about 50 percent of the “spaces” being neutral plane areas or spaces.  
         [0044]     It will, also be apparent that because the embossings  30 ,  34  that form the rows  26  also are the embossings  30 ,  34  that form the columns  28 , each of the embossings  30 ,  34  will have a row designation and a column designation, and in this manner form a matrix.  
         [0045]     As seen in  FIG. 5 , the rows  26  and the columns  28  are formed in a curved pattern or having a curved path. That is, the rows  26  and columns  28  do not form a straight line (are not rectilinear). Rather, the rows  26  and columns  28  are formed, preferably, having a sinusoidal pattern. In a contemplated wrap  10 , the sine curves have a pitch of about 2.0 inches, and a peak to peak amplitude of about 0.25 inches. The embossings  30 ,  34  are formed having a side length  130  of about 0.05 inches (about 50 mils) and a depth d 30  of about 0.035 inches (about 35 mils). The embossing “density” is about 40 embossings  30 ,  34  per side per repeating pattern (based on a 2 inch pitch) or about 1600 embossings per four square inches (or about 400 embossings per square inch). In a contemplated film  10 , the embossings  30 ,  34  are each formed as a truncated pyramid having a parallelogram base (see  FIG. 10 ). That is, the embossings  30 ,  34  are formed having four substantially equal length sides l 30  (not necessarily square, but in a parallelogram shape, see e.g.,  FIG. 3 ), that taper inwardly in the upward direction (away from the neutral plane P 32 ) at an angle α of about 15 degrees.  
         [0046]     One tool  36  for forming the embossed film  10  is illustrated in  FIGS. 1-2  and  7 , in which  FIG. 7  illustrates two of regions of an embossing roller  38 . A reference or neutral plane P 32  is defined by the roller  38  which corresponds to the neutral spaces  32  in the film  10  of  FIG. 5 . Projections  42  then extend outwardly from the roller  38  a height or distance d 42  of about 35 mils from the neutral plane P 32 . The projections  42  are formed having a truncated square pyramidal shape with the sides  44  tapering inwardly at an angle β of about 15 degrees relative to a line perpendicular to the neutral plane P 32 . The peaks  46  of the projections  42  are flat and the valleys  48  between the projections  42  (at the neutral plane P 32 ) are flat. As will be understood, the “projections”  42  form negative embossings  34 .  
         [0047]     In addition to the projections  42 , recesses  50  are also formed in the roller  38  that form the positive embossings  30 . The recesses  50  are formed in a mirror image relation to the projections  42 ; that is, the recesses  50  have a flat base  52  (corresponding to the neutral plane P 32 ) and sides  54  formed at an angle β of about 15 degrees relative to a line perpendicular to the neutral plane P 32 .  
         [0048]     The film  10  itself exhibits enhanced strength and tear resistance due to its cross-laminated structure. Those skilled in the art will recognize that the orientation of a plastic layer is a characteristic that is imparted to the film during manufacture. Typically, a polymer is melted and extruded into a bubble form from an extruder die. The film is then cooled, for example, using an annular air-ring (blown film process). The cooled bubble is collapsed to form layflat tubing which is then stretched. It is the extrusion and stretching operations that “orient” the film. Essentially, the long chain polymer molecules are oriented or directed as a result of the extrusion and stretching processes. The oriented layflat tubing so produced is then bias cut to produce a single layer of film where the orientation angle is at the desired angle to the machine direction.  
         [0049]     One process (indicated generally at  60 ) for making the film  10  is illustrated in part and schematically in  FIG. 12 . In the film forming portion of the process (which is referred to as an extrusion lamination process), a station  62  is used to apply the cross-oriented laminate films  16 ,  18  to one another with a bonding material applicator  64  positioned to apply the bonding or adhesive sealing material  20  between the plastic layers  16 ,  18  at about a roller nip  66 . Alternately, the plastic layers  16 ,  18  can be disposed directly on one another without the use of the bonding or sealing layer. In a contemplated film, however, the bonding layer  20  is disposed between the plastic layers  16 ,  18 , which bonding layer  20  is formed from a media, such as low density polyethylene or the like.  
         [0050]     This process forms a flexible, cross-laminated film or membrane  14 , which is then conveyed to a second (or embossing) station  68 , at which the membrane  14  is fed into the nip  70  of the embossing rollers  38 ,  40  to form the embossed film  10 . The film  10  is perforated for permeability to permit the passage of water vapor but to preclude the passage of liquid water.  
         [0051]     With respect to the material, it also is contemplated that adhesive laminations could be used as an alternative to extrusion lamination. In such a process, it is anticipated that a polymer (e.g., polyurethane) adhesive system is used. However, other polymeric adhesive systems are also contemplated. If needed, some arrangement of drying ovens can be used to remove solvents (from the adhesive) or the like.  
         [0052]     An alternate embossing pattern  110  is illustrated in  FIGS. 13-15 . In this embodiment  110 , the rows  126  and columns  128  are spaced so that adjacent rows or columns (of pairs of embossings  130 ,  134 ) are staggered relative to adjacent columns  126 , or rows  128 .  
         [0053]     For example, the embossings in the second row  126 B are in columnar alignment with the embossings in the fourth row  126 D and the sixth row  126 F, but are staggered relative to the embossings in the first row  126 A, the third row  126 C, the fifth row  126 E, and so on (which are in columnar alignment with one another). Likewise, the embossings in the first column  128 A are in row-alignment with the embossings in the third column  128 C, and so one, but are staggered from those in the second column  128 B, fourth column  128 D, and so on.  
         [0054]     The embossings  130 ,  134  are formed as three-dimensional elongated ovals having curved or rounded upper and lower ends  136  with elongated mid-sections  138 . Essentially, the embossings  130 ,  134  have a race-track-like shape. As seen in  FIG. 14 , when viewed in the direction perpendicular to the plane of the web  110  (i.e., a cross-section), the embossings  130 ,  134  have curved side walls  140  with flattened peaks  142  and troughs  144 .  
         [0055]     The present house-wrap  10 ,  110 , unlike the continuous channel type formed in known barrier materials, is formed by discrete, spaced apart formations  30 ,  34 ,  130 ,  134  in the web  14 . A present house-wrap film  10 ,  110  functions independent of the orientation at which it is installed on the structure B. Most desirably, such a material  10 ,  110  has a high tear resistance and high overall strength to permit use in all construction situations and at all sites.  
         [0056]     While specific embossing patterns, profiles, shapes and orientations have been describes, it is to be understood that various other patterns, profiles, shapes and orientations are contemplated by the present invention and are within the scope of the present invention.  
         [0057]     All patents referred to herein, are hereby incorporated herein by reference, whether or not specifically done so within the text of this disclosure.  
         [0058]     In the disclosures, the words “aα or “anα are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular.  
         [0059]     From the foregoing it will be observed that numerous modification and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.