Abstract:
An improved embossing, in the form of a sinusoidal wave on the sidewall of a thermoformed foam polymeric article, not only gives the article the enhanced vertical strength of embossed arches, but additionally provides enhanced radial strength. This results in an embossed article having both improved vertical strength and improved radial strength, which is desirable for many applications, including food containers.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Application No. 60/961,907, filed Jul. 24, 2007, which is expressly incorporated herein in its entirety by reference thereto. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention generally relates to a method for producing thermoformed articles having improved strength, and to articles produced by the method. 
       BACKGROUND OF INVENTION 
       [0003]    Thermoplastic foams have found wide utility in areas such as packaging. Such foams are typically molded into useful articles using a technology known as thermoforming. In this method, a polymeric sheet is heated to a softening point and then molded using a matched mold (male and female mold) in which a vacuum is created to ensure good mold contact between the foam and both surfaces of the matched mold. The mold is then chilled, freezing the article into the useful shape defined by the surfaces of the matched mold. The article is then trimmed to provide the article for use. 
         [0004]    It is well known within the industry that molding of geometry into the article can improve strength, thereby allowing less material to be used while achieving the same functionality. Examples of such geometry include ribs and short arches. Many foam food packaging manufacturers use such geometry in order to improve strength and/or aesthetics. In general, such geometry is embossed on one surface of the article to improve the vertical strength of a sidewall of the article when the article is resting on a flat surface. Some manufacturers, such as Pactiv Inc., use embossing on opposite surfaces for added strength. One commonality in all such designs is that the improvement in strength is directed to vertical sidewall strength. 
         [0005]    However, a need exists for a reduction of material usage per article via improvements in design. In this regard, arches are known in nature to have tremendous strength of design when used for vertical loading. Further, an arch represents a short section of a continuous sinusoidal wave. 
       SUMMARY OF INVENTION 
       [0006]    We have found that by embossing a sinusoidal wave into a sidewall of a formed article, not only is the vertical strength of the arches realized but also radial strength is improved. This results in an embossed article having both improved vertical strength and improved radial strength, which is desirable for many applications. 
         [0007]    The embossing of this invention is in the form of a sinusoidal wave which may be embossed on one surface or two opposite surfaces of an article formed from foam polymer. As used herein, and as recognized by those in the art, opposite surfaces refer to the two surfaces on opposing sides of a wall having a thickness. Embossing on two opposite surfaces of an article provides enhanced strength and is generally most effective when the embossing on one surface is directly opposite of the embossing on the opposite surface. 
         [0008]    Further, the embossing has been found to work with all types of sinusoidal waves. It is generally most effective when the period of the sinusoidal wave is twice its amplitude, or alternatively, when the amplitude of the sinusoidal wave is half its period. This results in a square sinusoidal wave which confers significant strength to the article. 
         [0009]    Additionally, the embossing appears to be most effective when the amplitude of the sinusoidal wave is 80% or more of the height of a sidewall or other surface to which it is applied. As used herein, the height of a sidewall of an article is generally measured approximately from the midpoint of the radius that transitions from a flat surface (top or bottom generally) to the sidewall, and extends to the midpoint of the radius that transitions from the sidewall to the rim. 
         [0010]    An added benefit is that when such geometry is utilized, significant reductions in material usage can be realized without the loss of part strength. The sinusoidal embossing imparts both vertical strength and radial strength to a surface, resulting in an article that can withstand handling and transport without the need for additional wall thickness, and the consequent use of more materials. 
         [0011]    The articles can be used for any application, but are particularly useful as food containers or plates. Food containers are especially preferable since these containers generally have top and bottom surfaces separated by sidewalls to which the sinusoidal embossing may be applied. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0012]      FIG. 1  presents a top perspective view of a first exemplary embodiment, a circular plate article containing a sinusoidal embossing along its perimeter. 
           [0013]      FIG. 2  presents a bottom perspective view of the first exemplary embodiment shown in  FIG. 1 . 
           [0014]      FIG. 3A  presents a top plan view of a second exemplary embodiment, a circular plate article containing a sinusoidal embossing along its perimeter. 
           [0015]      FIG. 3B  presents a cross-sectional view taken along line A-A of the second exemplary embodiment shown in  FIG. 3A . 
           [0016]      FIG. 3C  presents a cross-sectional view taken along line D-D of the second exemplary embodiment shown in  FIG. 3A . 
           [0017]      FIG. 3D  presents a magnified, cross-sectional view of the region F of the second exemplary embodiment shown in  FIG. 3C . 
           [0018]      FIG. 3E  presents a magnified, cross-sectional view of the region G of the second exemplary embodiment shown in  FIG. 3B . 
           [0019]      FIG. 4  presents a top perspective view of a third exemplary embodiment, a hinged container in a nearly closed position, containing a sinusoidal embossing on its upper and lower sidewalls. 
           [0020]      FIG. 5  presents a top perspective view of the third exemplary embodiment shown in  FIG. 4 , in an approximately half-open position. 
           [0021]      FIG. 6A  presents a top plan view of a fourth exemplary embodiment, a hinged container in a fully open position, containing a sinusoidal embossing on its upper and lower sidewalls. 
           [0022]      FIG. 6B  presents a side view of the fourth exemplary embodiment shown in  FIG. 6A . 
           [0023]      FIG. 6C  presents a cross-sectional view taken along line A-A of the fourth exemplary embodiment shown in  FIG. 6B . 
           [0024]      FIG. 6D  presents a cross-sectional view taken along line B-B of the fourth exemplary embodiment shown in  FIG. 6B . 
           [0025]      FIG. 6E  presents a magnified, cross-sectional view of the region C of the fourth exemplary embodiment shown in  FIG. 6C . 
           [0026]      FIG. 7A  presents a photograph of a top perspective view of the first exemplary embodiment. 
           [0027]      FIG. 7B  presents a photograph of a bottom perspective view of the first exemplary embodiment shown in  FIG. 7A . 
           [0028]      FIG. 8A  presents a photograph of a top perspective view of the third exemplary embodiment, in an approximately quarter-open position. 
           [0029]      FIG. 8B  presents a photograph of a top perspective view of the third exemplary embodiment shown in  FIG. 8A , in a closed position. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
     First Exemplary Embodiment 
       [0030]      FIGS. 1 ,  2 ,  7 A, and  7 B illustrate multiple views and photographs of a first exemplary embodiment, a circular plate article  10   a  containing a sinusoidal embossing  20  along its perimeter. 
         [0031]      FIG. 1  illustrates a top perspective view of the circular plate article  10   a , showing the sinusoidal embossing  20  along the perimeter of the article  10   a . Similarly,  FIG. 2  illustrates a bottom perspective view of the circular plate article  10   a , showing the sinusoidal embossing  20  along the perimeter of the article  10   a . In the first exemplary embodiment of  FIGS. 1 and 2 , the circular plate article  10   a  has multiple pockets  11  separated from each other by ridges  12 . The sinusoidal embossing in this first exemplary embodiment is shown as continuous over each pocket  11  between the ridges  12 . Further, the sinusoidal embossing  20  has been formed on two directly opposite surfaces along the perimeter of the article  10   a . In addition, the sinusoidal embossing  20  is shown as a square sinusoidal wave, i.e., the period of the sinusoidal wave is twice its amplitude, or alternatively, the amplitude of the sinusoidal wave is half its period. Also, the amplitude of the sinusoidal wave is shown as being at least 80% of the height of the sidewall. All of these features confer significant strength to the article  10   a.    
       Second Exemplary Embodiment 
       [0032]      FIGS. 3A to 3E  illustrate multiple views of a second exemplary embodiment, a circular plate article  10   b  containing a sinusoidal embossing  20  along its perimeter. 
         [0033]      FIG. 3A  illustrates a top plan view of the circular plate article  10   b  containing a sinusoidal embossing  20  along its perimeter. In this second exemplary embodiment, the circular plate article  10   b  has only a single pocket  11 . The sinusoidal embossing  20  in this second exemplary embodiment is shown as continuous along the entire perimeter of the article  10   b . Further, the sinusoidal embossing  20  has been formed on two directly opposite surfaces along the perimeter of the article  10   b . In addition, the sinusoidal embossing  20  is shown as a square sinusoidal wave, i.e., the period of the sinusoidal wave is twice its amplitude, or alternatively, the amplitude of the sinusoidal wave is half its period. Also, the amplitude of the sinusoidal wave is shown as being at least 80% of the height of the sidewall. All of these features confer significant strength to the article  10   b.    
         [0034]      FIG. 3B  illustrates a cross-sectional view of the circular plate article  10   b , taken along the line A-A shown in  FIG. 3A . As shown, this cross-section is taken through the center point of the article  10   b  and through two peaks  21  of the sinusoidal embossing  20 . The two peaks  21  are on opposite edges of the article  10   b  along the perimeter. Further,  FIG. 3E  illustrates a magnified, cross-sectional view of one edge of the article  10   b , designated as Detail G in  FIG. 3B . This magnified, cross-sectional view more clearly shows the embossing at a peak  21 , the embossing  20  being shown on directly opposite surfaces of the article  10   b.    
         [0035]      FIG. 3C  illustrates a cross-sectional view of the circular plate article  10   b , taken along the line D-D shown in  FIG. 3A . As shown, this cross-section is taken through the center point of the article  10   b  and through two valleys  22  of the sinusoidal embossing  20 . The two valleys  22  are also on opposite edges of the article  10   b  along the perimeter. Further,  FIG. 3D  illustrates a magnified, cross-sectional view of an edge of the article  10   b , designated as Detail F in  FIG. 3C . This magnified, cross-sectional view more clearly shows the embossing at a valley  22 , the embossing  20  being shown on directly opposite surfaces of the article  10   b.    
       Third Exemplary Embodiment 
       [0036]      FIGS. 4 ,  5 ,  8 A, and  8 B illustrate multiple views and photographs of a third exemplary embodiment, a hinged container  30   a  having a base  31  and a cover  32  connected by a hinge  37 . The base  31  includes multiple pockets  33  separated from each other by ridges  34 , and a lower sidewall  35  along the perimeter of the base  31 . The cover  32  includes a single pocket  33 , and an upper sidewall  36  along the perimeter of the cover  32 . The hinged container  30   a  includes a sinusoidal embossing  20  on the upper sidewall  36  of the cover  32 , and a sinusoidal embossing  20  on the lower sidewall  35  of the base  31 . 
         [0037]      FIG. 4  illustrates a top perspective view of the hinged container  30   a  in a nearly closed position, showing the sinusoidal embossing  20  on an outer surface of its upper sidewall  36 , and the sinusoidal embossing  20  on an outer surface of its lower sidewall  35 . Similarly,  FIG. 5  illustrates a top perspective view of the hinged container  30   a  in an approximately half-open position, showing the sinusoidal embossing  20  on an inner surface of its upper sidewall  36 , and the sinusoidal embossing  20  on an inner surface of its lower sidewall  35 . In the third exemplary embodiment of  FIGS. 4 and 5 , the base  31  of the hinged container  30   a  has multiple pockets  33  separated from each other by ridges  34 , and the sinusoidal embossing  20  on the lower sidewall  35  of the base  31  is shown as continuous over each pocket  33  between the ridges  34 . The cover  32  of the hinged container  30  has a single pocket  33 , and the sinusoidal embossing  20  on the upper sidewall  36  of the cover  32  is shown as continuous along the entire perimeter of the cover  32 . 
         [0038]    Further, the sinusoidal embossing  20  has been formed on two opposite surfaces of each of the lower sidewall  35  and the upper sidewall  36  of the article  30   a . In addition, the sinusoidal embossing  20  is shown as a square sinusoidal wave, i.e., the period of the sinusoidal wave is twice its amplitude, or alternatively, the amplitude of the sinusoidal wave is half its period. Also, the amplitude of the sinusoidal wave is shown as being at least 80% of the height of each of the lower sidewall  35  and the upper sidewall  36  to which the sinusoidal wave is applied. All of these features confer significant strength to the article  30   a.    
       Fourth Exemplary Embodiment 
       [0039]      FIGS. 6A to 6E  illustrate multiple views of a fourth exemplary embodiment, a hinged container  30   b  having a base  31  and a cover  32  connected by a hinge  37 . The base  31  includes a single pocket  33 , and a lower sidewall  35  along the perimeter of the base  31 . The cover  32  also includes a single pocket  33 , and an upper sidewall  36  along the perimeter of the cover  32 . The hinged container  30   b  includes a sinusoidal embossing  20  on the upper sidewall  36  of the cover  32 , and a sinusoidal embossing  20  on the lower sidewall  35  of the base  31 . 
         [0040]      FIG. 6A  illustrates a top plan view of the hinged container  30   b  in a fully open position, containing a sinusoidal embossing  20  on an inner surface of its upper sidewall  36 , and a sinusoidal embossing  20  on an inner surface of its lower sidewall  35 . The sinusoidal embossing  20  on the lower sidewall  35  of the base  31  is shown as continuous along the entire perimeter of the base  31 , and the sinusoidal embossing on the upper sidewall  36  of the cover  32  is also shown as continuous along the entire perimeter of the cover  32 . 
         [0041]    Further, the sinusoidal embossing  20  has been formed on two directly opposite surfaces on each of the lower sidewall  35  and the upper sidewall  36  of the article  30   b . In addition, the sinusoidal embossing  20  is shown as a square sinusoidal wave, i.e., the period of the sinusoidal wave is twice its amplitude, or alternatively, the amplitude of the sinusoidal wave is half its period. Also, the amplitude of the sinusoidal wave is shown as being at least 80% of the height of each of the lower sidewall  35  and the upper sidewall  36  to which the sinusoidal wave is applied. All of these features confer significant strength to the article  30   b.    
         [0042]      FIG. 6B  illustrates a side view of the hinged container  30   b . The side view of the hinged container  30   b  more clearly shows that the sinusoidal embossing  20  has been formed on two directly opposite surfaces on each of the lower sidewall  35  and the upper sidewall  36  of the article  30   b . This side view also more clearly shows that the amplitude of the sinusoidal wave is at least 80% of the height of each of the lower sidewall  35  and the upper sidewall  36  to which the sinusoidal wave is applied.  FIG. 6C  illustrates a cross-sectional view of the hinged container  30   b , taken along the line A-A shown in  FIG. 6B . As shown, this cross-section is taken through the base  31  at an approximate midpoint between the hinge  37  and the edge of the base  31  opposite the hinge  37 , such that the cross-section cuts through two valleys  38  of the sinusoidal embossing  20 . The two valleys  38  are on opposite edges of the base  31  along the perimeter. Further,  FIG. 6E  illustrates a magnified cross-sectional view of a lower edge of the base  31  of the hinged container  30   b , designated as Detail C in  FIG. 6C . This magnified, cross-sectional view more clearly shows the embossing at a valley  38 , the embossing  20  being shown on directly opposite surfaces of the lower sidewall  35  of the article  30   b.    
         [0043]      FIG. 6D  illustrates a cross-sectional view of the hinged container  30   b , taken along the line B-B shown in  FIG. 6B . As shown, this cross-section is taken through the cover  32  at an approximate midpoint between the hinge  37  and the edge of the cover  32  opposite the hinge  37 , such that the cross-section cuts through two peaks  39  of the sinusoidal embossing  20 . The two peaks  39  are on opposite edges of the cover  32  along the perimeter. 
         [0044]    In addition to the above described exemplary embodiments, other useful articles, such as cups and other storage containers can also be embossed about their perimeter to achieve the additional strength needed. 
         [0045]    Further, although the above described embodiments have been shown with a particular shape, size, location, placement, and other features of the sinusoidal embossing on the articles, the above embodiments are described by way of example only. For example, the amplitude and/or period of the sinusoidal embossing may be varied. In addition, the size and/or thickness of the sinusoidal embossing may also be varied. Further, the height of the sinusoidal embossing relative to the height of the sidewall or other surface to which it is applied may be varied. Also, the specific location and placement of the sinusoidal embossing on the surfaces as well as the relative locations of the peaks and valleys of the sinusoidal embossing may be varied. 
         [0046]    It is apparent that many modifications and variations of this invention as hereinabove set forth may be made without departing from the spirit and scope thereof. The specific embodiments described are given by way of example only, and the invention is limited only by the terms of the appended claims. 
       EXPERIMENTAL RESULTS 
       [0047]    Deflection Data Comparison of Darnel “Wave Design” 9 inch foam plates versus Pactiv, CVS, and Genpak 9 inch foam plates. 
       Samples 
       [0048]    Four samples were evaluated for design characteristics and strength performance: Darnel plate—product code DU5009191 (Darnel), Pactiv Placesetter©—product code 721725720058 (Pactiv), CVS Pharmacy “Foam Plates” (CVS), and Genpak Celebrity©—product code 80900 (Genpak). All four samples were nominal diameter 9″ polystyrene foam plates. These products are sold into the same markets for the same purposes and are therefore believed to be directly comparable. Of these four samples, the CVS samples are a store brand believed to be manufactured by another entity. 
       Testing 
       [0049]    The following tests were performed on each of the samples: Product Weight, Diameter, Thickness, Cell Size, and Deflection. The procedure and results of each test are discussed below. 
       Product Weight 
       [0050]    Ten plates of each sample were weighed using a Tanita Model 1479V gram scale. The weight was recorded, and the average and standard deviation were calculated. The results are shown in Table 1. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Sample 
                 Average Weight 
                 Standard Deviation 
               
               
                   
                   
               
             
             
               
                   
                 Darnel 
                 5.34 Grams 
                 0.084 grams 
               
               
                   
                 CVS 
                 4.11 Grams 
                 0.088 grams 
               
               
                   
                 Genpak 
                 6.08 Grams 
                 0.140 grams 
               
               
                   
                 Pactiv 
                 4.24 Grams 
                 0.259 grams 
               
               
                   
                   
               
             
          
         
       
     
       Diameter 
       [0051]    The diameter of one plate from each sample was measured using a stainless steel ruler accurate to 1/32″ and recorded. Since the diameter of each sample is determined by machine tooling design, it is expected to be constant from plate to plate within each sample. The results are shown in Table 2. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Sample 
                 Diameter 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Darnel 
                 8⅞ 
                 inches 
               
               
                   
                 CVS 
                 8⅞ 
                 inches 
               
               
                   
                 Genpak 
                 8 13/16 
                 inches 
               
               
                   
                 Pactiv 
                 8⅞ 
                 inches 
               
               
                   
                   
               
             
          
         
       
     
       Thickness 
       [0052]    One section was cut out of one plate from each sample. Each section was cut from the same location of each sample, i.e., from the bottom surface near the center. A Mitutoyo Absolute Digimatic micrometer was used to measure thickness. Similar to the diameter of each sample as described above, the thickness of each sample is also determined by machine tooling design, and as such, it is expected to be constant from plate to plate within each sample. The results are shown in Table 3. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Sample 
                 Thickness 
               
               
                   
                   
               
             
             
               
                   
                 Darnel 
                 0.078 inches 
               
               
                   
                 CVS 
                 0.056 inches 
               
               
                   
                 Genpak 
                 0.074 inches 
               
               
                   
                 Pactiv 
                 0.055 inches 
               
               
                   
                   
               
             
          
         
       
     
       Cell Size 
       [0053]    The same sections of each sample that were cut out and used for the thickness test were also used for the cell size test. An SPI Zoom Lupe 816 microscope using a magnification of 16× was used to view the cell structure at a clean cut through the thickness of each section. An approximate cell count of the number of cells between opposite surfaces of each section was made, following a line perpendicular to the opposite surfaces. The cell size of each sample was calculated by dividing the thickness of each sample by the approximate cell count. The results are shown in Table 4. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 Sample 
                 Cell Size 
               
               
                   
                   
               
             
             
               
                   
                 Darnel 
                 0.0052 inches 
               
               
                   
                 CVS 
                 0.0093 inches 
               
               
                   
                 Genpak 
                 0.0053 inches 
               
               
                   
                 Pactiv 
                 0.0069 inches 
               
               
                   
                   
               
             
          
         
       
     
       Deflection 
       [0054]    Ten plates of each sample were tested for deflection performance. In this test, one half of each plate was supported by the top surface of a first table. The free (or unsupported) half of each plate was set up over a second table, leaving a gap of about two inches between the bottom surface of the free half of each plate and the top surface of the second table. The distance between the bottom surface of the free half of each plate and the top surface of the second table was then measured using a stainless steel ruler accurate to 1/32″. This number was recorded as the zero point, or non-deflected starting point. A steel weight of 390 grams was then placed on the unsupported half of each plate at a location as near to the rim and as far from the first supporting table as possible. The distance between the bottom surface of the free half of each plate and the top surface of the second table was again measured, yielding a deflected measurement. By subtracting the zero point from the deflected measurement, the actual deflection was determined. This number was recorded to an accuracy of 1/16 of an inch. The results of the deflection measurements of the ten plates of each sample were averaged, and the standard deviation was also calculated. The results are shown in Table 5. 
         [0000]                                    TABLE 5                       Sample   Average Deflection   Standard Deviation                           Darnel    17/32 inch   0.084 inches           CVS    29/32 inch   0.132 inches           Genpak    17/32 inch   0.060 inches           Pactiv    28/32 inch   0.066 inches                        
As to deflection, greater deflection correlates to poorer performance. The greater the deflection value, the more likely a plate will bend and spill its contents at a given load. In other words, a product with a lower deflection value at a given load will support more food without failure than a product with a higher deflection value at the same load.
 
       Discussion of Results 
       [0055]    To understand the data, the design characteristics of each sample must first be considered. It is known by one skilled in the art that the addition of sidewall geometry improves stiffness and strength of thermoformed products whether those products consist of solid or foam plastic. In this regard, the CVS and Genpak samples have embossing on the rim only. Such geometry would not be expected to significantly add to the strength of the product. The Pactiv sample has an arch design on the sidewall, but the arch itself is again confined to the rim area. In addition, only straight embossing proceeds down the sidewall of the Pactiv sample. 
         [0056]    The Darnel sample is embossed with a sinusoidal wave, the sinusoidal wave having an amplitude of approximately 80% of the height of the sidewall. The following is hypothesized regarding the Darnel sample. The sinusoidal wave design imparts strength to the entire sidewall. By using a sinusoidal wave function, the emboss line continuously changes its angle on the sample so as not to impart a hinge point. In addition, deflection of such samples occurs in a parabolic fashion, instead of a linear fashion. As such, the sinusoidal wave design geometry crosses any potential bend line at nearly 90 degrees, giving maximum resistance to bending. It should be noted that the sinusoidal embossing is provided on opposite surfaces of the sample, thus providing structural reinforcement, instead of a single-sided ornamental embossing. 
         [0057]    If the above hypothesis is true, then the Darnel design should show improved strength, and consequently less deflection, than other products. However, other factors can also affect strength, including weight, thickness, cell size, and others. A product having greater weight per part will generally also have greater strength. In addition, a product having greater thickness will generally be less susceptible to bending. Further, it is well known in the industry that a larger cell size will create a stiffer product, but at the price of greater brittleness, whereas a smaller cell size will create a more flexible product, but with lower stiffness. Therefore, in order to best compare the samples, as many factors as possible should be considered. 
         [0058]    The most direct comparison appears to be that between the Darnel and Genpak samples. These samples are not significantly different in either thickness or cell size, which means that the deflection values likely should reflect only the differences in sample weight and geometry. Since the Genpak sample has significantly greater weight, and if geometry does not affect deflection, then the deflection performance of the Genpak sample should be better than that of the Darnel sample. However, the average deflection values of these two samples are essentially identical. Although the weight of the Darnel sample is 13% less than that of Genpak sample, the Darnel sample has deflection strength equal that of the heavier Genpak sample. This, therefore, is an indicator that the geometry used in the Darnel product yields a finished good of improved performance, i.e., greater strength and lower weight. 
         [0059]    Since the CVS and Pactiv samples are similar in thickness, cell size, weight, and measured deflection, they can both be compared to the Darnel sample using similar logic. Although the thickness of the Darnel sample is approximately 30% greater and its weight is approximately 20% greater than those of the CVS and Pactiv samples, the cell size of the CVS and Pactiv samples is far greater. Greater thickness and weight would contribute to greater strength for the Darnel sample, but the greater cell size of the CVS and Pactiv samples would impart greater stiffness in those products. Yet the deflection measured for the Darnel samples is only about one half of that of the CVS and Pactiv samples. 
         [0060]    It is noted that there are many other variables that may contribute to the testing performance of the tested samples. Other variables may include foam composition, foam quality, coatings, and other product dimensions and features, among others. These and other possible variables were not evaluated in the testing described above, and no representation is made as to these characteristics of the tested samples other than those specifically discussed above. Nonetheless, given the data from the testing described above and making the best interpretation of that data, one skilled in the art would reasonably conclude that the sinusoidal geometry of the Darnel sample improves the deflection strength of the Darnel sample.