Abstract:
The present invention is the apparatus and method for producing a plastic sheet having a pattern produced in a layer therein. The plastic sheet is a single layer sheet or a multi-layer sheet. The pattern is produced by mixing two or more plastic extrudants together in a mixer. The pattern is visible in the layer containing the two or more plastic extrudants because an at least one of the plastic extrudants is at least partially transparent. The mixer used to produce the pattern includes a housing having an end configured to expel the mixture of the two or more extrudants through a plurality of outlets. The mixer further comprises a rotatable shaft and at least one projection coupled to the shaft and rotatable with the shaft, the at least one projection configured to orient the mixture of the two or more extrudants relative to the plurality of outlets in the housing. The mixer further comprising a thrust bearing configured to couple an end of the shaft to the housing.

Description:
RELATED APPLICATIONS 
   This application is a division of application Ser. No. 09/894,032 filed Jun. 28, 2001, the disclosure of which is hereby expressly incorporated by reference. 

   FIELD OF THE INVENTION 
   The present invention relates to the production of a plastic sheet and the process and apparatus for producing the plastic sheet and in particular to the production of a plastic sheet having a decorative appearance and, the process and apparatus for producing the plastic sheet with the decorative appearance. 
   BACKGROUND 
   Various products have been produced by vacuum forming a plastic sheet into the desired shape of the product. Example products include slides for outdoor play equipment, showers, food trays and hunting accessories. The plastic sheet used in the vacuum forming process typically has an aesthetic side and a non-aesthetic side. The plastic sheet has generally had uniform coloration on both the non-aesthetic side and the aesthetic side. 
   The plastic sheet is often made from at least two layers of extruded plastic. The first layer is a base layer that is made from recycled plastic and provides the non-aesthetic side. The second layer is a colored layer which contains the coloration for the aesthetic side of the plastic sheet. The use of multiple layers reduces cost by allowing manufacturers to reuse scrap plastic for the base layer (non-aesthetic side) and to minimize the amount of new plastic needed to create the aesthetic side. 
   SUMMARY OF INVENTION 
   The present invention is the apparatus and method for producing a plastic sheet having a pattern produced therein. 
   In one exemplary embodiment, an apparatus for producing a non-linear pattern from a mixture of at least two extrudants in an extrusion process comprising a housing having a first end and a second end and an interior region. The first end of the housing being adapted to receive the mixture of at least two extrudants and the second end of the housing being configured to expel the mixture of the at least two extrudants in a non-linear pattern. The second end of the housing including a plurality of outlets to selectively expel the mixture. The apparatus further includes a shaft having a first end and a second end. The first end of the shaft located proximate to the first end of the housing and the second end of the shaft located proximate to the second end of the housing. The shaft being rotatable relative to the housing about an axis. The apparatus further includes at least one projection coupled to the shaft and rotatable with the shaft. The at least one projection configured to orient the mixture relative to the plurality of outlets in the second end of the housing. The apparatus further comprising a thrust bearing configured to couple the second end of the shaft to the second end of the housing to permit the expulsion of the mixture in a non-linear pattern as the mixture is oriented relative to the plurality of outlets. 
   In another exemplary embodiment, an apparatus for producing a multi layer plastic extrudant comprising a first extruder configured to extrude a first plastic extrudant, a second extruder configured to extrude a second plastic extrudant, the second plastic extrudant being at least partially transparent and a third extruder configured to extrude a third plastic extrudant. The apparatus further comprises a mixer coupled to the second extruder and the third extruder. The mixer being configured to produce a mixture of the second plastic extrudant and the third plastic extrudant, the mixture including a non-linear pattern. The apparatus further comprising a co-extrusion block comprising a first channel and a second channel, wherein the first channel is coupled to the first extruder to receive the first plastic extrudant to produce a first layer and wherein the second channel is coupled to the mixer to receive the mixture of the second plastic extrudant and the third plastic extrudant to produce a second layer. The second layer containing the non-linear pattern wherein the third plastic extrudant of the mixture is visible within the second layer due to the second plastic extrudant of the mixture being at least partially transparent. 
   In another exemplary embodiment, the mixer of the preceding embodiment comprising a housing having a first end and a second end and an interior region. The first end of the housing being configured to receive the second plastic extrudant and the third plastic extrudant and the second end of the housing being configured to expel the mixture of the two extrudants through a plurality of outlets. The mixer further comprising a shaft having a first end and a second end. The first end of the shaft located proximate to the first end of the housing and the second end of the shaft located proximate to the second end of the housing. The shaft being rotatable relative to the housing about an axis. The mixer further comprising at least one projection coupled to the shaft and rotatable with the shaft, the at least one projection configured to orient the mixture of the two extrudants relative to the plurality of outlets in the second end of the housing. The mixer further comprising a thrust bearing configured to couple the second end of the shaft to the second end of the housing to permit expulsion of the mixture in a non-linear pattern as the mixture is oriented relative to the plurality of outlets. 
   In one exemplary embodiment, a plastic sheet is produced comprising a first layer comprising a plastic extrudant and a second layer coupled to the first layer, the second layer comprising at least two other plastic extrudants. The plastic extrudants of the second layer produce a pattern wherein at least one of the plastic extrudants is at least partially transparent such that both of the plastic extrudants are visible in the second layer. 
   In one exemplary embodiment, a method for producing a plastic sheet, comprising the steps of extruding a first plastic extrudant to produce a first layer, extruding a second plastic extrudant having an appearance, the appearance being at least partially transparent and including a first color, and extruding a third plastic extrudant having another appearance, the other appearance including a second color. The method further comprising mixing the second plastic extrudant and the third plastic extrudant to produce a mixture, the mixture including a non-linear pattern. The method further comprising applying the mixture of the second and third plastic extrudant to the first layer to produce a second layer wherein the third plastic extrudant of the mixture is visible within the second layer due to the appearance of the second plastic extrudant of the mixture. 
   In another embodiment the step of mixing the second and third plastic extrudants in the preceding embodiment comprising the steps of dividing the second plastic extrudant and the third plastic extrudant to produce the mixture, positioning the mixture proximate to a selection member having a plurality of outlets, and selectively expelling the mixture though the plurality of outlets such that a first portion of the mixture is expelled through a first outlet at a first instance of time and such that the first portion is not expelled from the first outlet at a second instance of time. 
   In another embodiment of the preceding embodiment, the step of selectively expelling the mixture comprising the steps of rotating at least one of either the selection member or the mixture relative to the other of the selection member or the mixture and applying a force to the mixture to expel the first portion through the first outlet at the first time. 
   In yet another embodiment, a method for producing a plastic sheet comprising the steps of extruding a first plastic extrudant having a first appearance, the first appearance being at least partially transparent and including a first color, and extruding a second plastic extrudant having a second appearance, the second appearance including a second color. The method further includes mixing the first plastic extrudant and the second plastic extrudant to produce a mixture having a non-linear pattern and producing a sheet from the mixture, the second plastic extrudant being visible within the sheet due to the appearance of the first plastic extrudant. 
   In another embodiment of the preceding embodiment the step of mixing the first plastic extrudant and the second plastic extrudant comprising the steps of dividing the first plastic extrudant and the second plastic extrudant to produce the mixture, positioning the mixture proximate to a selection member having a plurality of outlets, and selectively expelling the mixture though the plurality of outlets such that a first portion of the mixture is expelled through a first outlet at a first instance of time and such that the first portion is not expelled from the first outlet at a second instance of time. 
   In a further embodiment, an apparatus for producing a plastic extrudant comprising a first extruder configured to extrude a first plastic extrudant, a second extruder configured to extrude a second plastic extrudant, the second plastic extrudant being at least partially transparent, and a mixer coupled to the first extruder and the second extruder. The mixer being configured to produce a mixture of the first plastic extrudant and the second plastic extrudant, the mixture including a non-linear pattern. The apparatus further comprising a die coupled to the mixer to receive the mixture of the first plastic extrudant and the second plastic extrudant to produce a layer. The layer containing the non-linear pattern wherein the first plastic extrudant of the mixture is visible within the layer due to the second plastic extrudant of the mixture being at least partially transparent. 
   In yet a further embodiment of the preceding embodiment, the mixer comprises a housing having a first end and a second end and an interior region. The first end of the housing being configured to receive the first plastic extrudant and the second plastic extrudant and the second end of the housing being configured to expel the mixture of the two extrudants through a plurality of outlets. The mixer further comprising a shaft having a first end and a second end. The first end of the shaft located proximate to the first end of the housing and the second end of the shaft located proximate to the second end of the housing, the shaft being rotatable relative to the housing about an axis. The mixer further comprising at least one projection coupled to the shaft and rotatable with the shaft, the at least one projection configured to orient the mixture of the two extrudants relative to the plurality of outlets in the second end of the housing. The mixer further comprising a thrust bearing configured to couple the second end of the shaft to the second end of the housing to permit expulsion of the mixture in a non-linear pattern as the mixture is oriented relative to the plurality of outlets. 
   In another embodiment, a plastic sheet is produced comprising a first plastic extrudant and a second plastic extrudant. The second plastic extrudant is mixed with the first plastic extrudant to produce a pattern. The second plastic extrudants is at least partially transparent such that both the second plastic extrudant and the first plastic extrudant are visible in the sheet. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top view of a first exemplary embodiment of a plastic sheet of the present invention; 
       FIG. 2  is a cross-sectional view of the plastic sheet of  FIG. 1  along lines  2 — 2 ; 
       FIG. 3  is a block diagram representation of a co-extrusion process for producing the plastic sheet illustrated in  FIG. 1 ; 
       FIG. 4  is an exemplary cross-section of the plastic extrudant exiting the collection box of  FIG. 3 , the plastic extrudant consisting of two extrudants; 
       FIG. 5  is an exemplary cross-section of the plastic extrudant exiting the segmentor of  FIG. 3 ; 
       FIG. 6  is a block diagram of a turbulator or mixer used in the co-extrusion process of  FIG. 3 ; 
       FIG. 7  is a side view of a portion of the turbulator of  FIG. 6 ; 
       FIG. 8  is a front view of a portion of the turbulator of  FIG. 6  illustrating the second end of the turbulator including the plurality of outlets; 
       FIG. 9  is the front view of  FIG. 8  including a representation of the orientation of the plastic extrudant in the interior of the turbulator relative to the plurality of outlets in the second end; and 
       FIG. 10  is a block diagram representation of a co-extrusion process for producing a single layer plastic sheet having a pattern formed therein. 
   

   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
   While the invention is susceptible to various modifications and alternative forms, exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
   Referring to  FIGS. 1 and 2 , a plastic sheet  100  is shown. Plastic sheet  100  includes a first layer  110  and a second layer  120 . First layer  110 , in one embodiment, is composed of a thermoplastic material, such as high density polyethylene, which has been extruded. Second layer  120 , in one embodiment, includes two or more thermoplastic materials, which have been extruded and combined in accordance with the present invention. In alternative embodiments, first and second layers are formed of a thermoset material. In  FIGS. 1 and 2 , second layer  120  includes a material  130  and a material  140 . Second layer  120  may have any number of additional materials. The present invention is not intended to be limited to only two materials in the second layer  120 . 
   Material  130  is a thermoplastic material which has a colored appearance due to the addition of a colorant to the base plastic. In an alternative embodiment, material  130  includes a colorant and an additional additive to enhance the appearance of material  130 . Example additional additives include aluminum flakes or other types of flakes for providing pearlescent effects, and flourescent dyes. 
   Material  140  is a thermoplastic material which has a colored appearance due to the addition of a colorant to the base plastic. In an alternative embodiment, material  140  includes a colorant and an additional additive to enhance the appearance of material  140 . Example additional additives include aluminum flakes or other types of flakes for providing pearlescent effects, and flourescent dyes. 
   In  FIGS. 1 and 2 , the amount of colorant added to material  130  is such that the appearance of material  130  is opaque and the amount of colorant added to material  140  is such that the appearance of material  140  is at least partially transparent or non-opaque. Due to the partial transparent appearance of material  140 , material  130  is visible within second layer  120  by an observer through an outer surface  150  of plastic sheet  100 . 
   Referring to  FIGS. 1 and 2 , material  130  creates a pattern in second layer  120 , such as swirl pattern  153 . Material  130  is divided into pattern components or swirls  154 ,  156 ,  158 ,  160 ,  162 ,  164  and  166 . Swirls  154 ,  156 ,  158 ,  160 ,  162 ,  164  and  166  are located at various positions within second layer  120 , such as: at outer surface  150 , at a bottom surface  168  and at intermediate positions between outer surface  150  and bottom surface  168 . Referring to  FIG. 2 , swirl  154  and swirl  160  are located at a first intermediate position  170 . Swirl  156  is located at a second intermediate position  172 . Swirl  158  is located at bottom surface  168 . The capacity to see the pattern  153  in material  130  even though swirls  154 ,  156 ,  158 ,  160 ,  162 ,  164  and  166  are at varying positions or heights in second layer  120  gives plastic sheet  100  a depth characteristic. If the appearance of material  140  was not at least partially transparent then only the pattern components which are located at outer surface  150  would be visible to an observer. 
   Plastic sheet  100  can be manufactured from any suitable thermoplastic material, such as polyethylene, high density polyethylene including a high molecular weight polyethylene, ABS (Acrylonitrile Butadiene Styrene) or polystyrene. In one embodiment, plastic sheet  100  has a thickness  174  in the range of 0.050 inches to 0.500 inches. In another embodiment, thickness  174  is in the range of 0.150 inches to 0.300 inches. In a preferred embodiment, thickness  174  is in the range of 0.100 inches to 0.350 inches. In one embodiment, second layer  120  has a thickness  175  in the range of 0.050 inches to 0.300 inches. In another embodiment thickness  175  is in the range of 0.050 inches to 0.250 inches. In the preferred embodiment thickness  175  is 0.250 inches. In one embodiment, plastic sheet  100  has a width  176  in the range of 4 to 90 inches. In another embodiment, width  176  is in the range of 2 to 100 inches. In yet another embodiment, width  176  is in the range of 12 to 80 inches. 
   Referring to  FIG. 3 , an exemplary embodiment  200  of the apparatus and process for manufacturing plastic sheet  100  is shown. Extruder  202  extrudes a plastic extrudant  204  which corresponds to the plastic in first layer  110 . Extruder  202  is a 2 inch extruder available from Welex, Inc. located at 850 Jolly Road, Blue Bell, Pa. 19422. Plastic extrudant  204  is feed into a Co-Extrusion Block  206  available from Davis Standard located at #1 Extrusion Drive, Pawcatuck, Conn. 06379. Co-Extrusion Block  206  includes a plurality of channels one of which receives plastic extrudant  204 . 
   Extruder  208  extrudes a plastic extrudant  210  which corresponds to the plastic in material  140  in second layer  120  in  FIGS. 1 and 2 . Extruder  208  is a 3.5 inch extruder available from Davis Standard. Extruder  212  extrudes a plastic extrudant  214  which corresponds to the plastic in material  130  in second layer  120  in  FIGS. 1 and 2 . Extruder  212  is a 2.5 inch extruder available from Welex, Inc. 
   Plastic extrudants  210  and  214  are presented to a mixer  225  to produce a mixture  232 . Plastic extrudants  210  and  214  are collected in a collection box  216 , available from Davis Standard. Collection box  216  produces a plastic extrudant or mixture  218  which includes both plastic extrudant  210  and plastic extrudant  214 . Referring to  FIG. 4 , plastic extrudant  210  and plastic extrudant  214  are generally segregated to separate portions of plastic extrudant  218 . 
   In alternative embodiments, mixture  218  further includes additional plastics having appearances differing from plastic extrudants  210  and  214 . In one embodiment, extruder  213  extrudes a plastic extrudant  215  which has an appearance differing from plastic extrudants  210  and  214 . Plastic extrudant  215  is collected in collection box  216  along with plastic extrudants  210  and  214 . Extruder  213  is manufactured by and available from Welex, Inc. In another embodiment, extruder  217  extrudes a plastic extrudant  219  having an appearance differing from plastic extrudants  210 ,  214  and  215 . Plastic extrudant  219  is collected in collection box  216  along with plastic extrudants  210 ,  214  and  215 . Extruder  217  is available from Welex, Inc. 
   In one embodiment, a green camouflage pattern is produced as second layer  120  with the mixing of the following three extrudants. Extruder  208  produces a plastic extrudant or mixture containing 99.5% of high density polyethylene (such as HMWPE) and 0.5% of color concentrate, the color being olive drab. Normally to produce an opaque extrudant, 4% of the mixture is colorant and 96% is HMWPE. By reducing the percentage of colorant used, the resultant extrudant or mixture is at least partially transparent. 
   In one embodiment, an ultra-violet inhibitor (UVI) stabilizer is added to the extrudant or mixture for outdoor applications of sheet  100 . Extruder  208  is a 3.5 inch extruder available from Davis-Standard operating at 90 rpm (revolutions per minute) and 350-400 pph (pounds per hour). The heat profile for the extrudant is a normal profile for a 10 HLMI (high load melt index) HMWPE material with a temperature between 420° F. and 450° F. The extrudant produced by extruder  208  is collected in collection box  216 . 
   Extruder  212  produces a plastic extrudant or mixture containing 96% HMWPE and 4% color concentrate, the color being black. Due to the 4% color concentrate, the extrudant is opaque. Extruder  212  is a 2.5 inch extruder available from Welex, Inc. operating at 2 rpm. The extrudant produced by extruder  212  is collected in collection box  216 . 
   Extruder  213  produces a plastic extrudant or mixture containing 96% HMWPE and 4% color concentrate, the color being dark green. Due to the 4% color concentrate, the extrudant is opaque. Extruder  213  is a 2.0 inch extruder available from Welex, Inc. operating at 38 rpm. The heat profile for the extrudant is a normal profile for a 10 HLMI HMWPE material with a temperature between 420° F. and 450° F. The extrudant produced by extruder  213  is collected in collection box  216 . 
   The extrudant exiting collection box  216  is composed of the at least partially transparent olive drab extrudant of extruder  208 , the black extrudant of extruder  212 , and the dark green extrudant of extruder  213 . The at least partially transparent olive drab extrudant comprises the majority of the extrudant exiting collection box  216  due to the operating speeds of extruders  208 ,  212 ,  213 . Extruder  208  which produces the olive drab extrudant is operating at 90 rpm and is a 3.5 inch extruder. Extruder  212  which produces the black extrudant is operating at 2 rpm and is a 2.5 inch extruder. Extruder  213  which produces the dark green extrudant is operating at 38 rpm and is a 2.0 inch extruder. 
   Various color variations can be achieved in second layer  120  through variations in the operating parameters of extruders  208 ,  212 ,  213  and the types and amounts of colorants used in each extruder. For example, in another embodiment, an arid camouflage pattern is produced with the same parameters as for green camouflage except that the speed of extruder  213 , corresponding to the flow rate for the green extrudant, is decreased from 38 rpm to 16 rpm and the speed of extruder  212 , corresponding to the flow rate for the black extrudant, is increased from 2 rpm to 4 rpm to produce a tan coloration. 
   Referring to  FIG. 3 , plastic extrudant or mixture  218  is presented to a segmentor  220  which divides plastic extrudant  210  and plastic extrudant  214  to produce a plastic extrudant or mixture  222 , generally as shown in FIG.  5 . Plastic extrudant or mixture  222  includes generally distinct segments of plastic extrudants  210  and  214 . In one embodiment, segmentor  220  is a homogeneous mixer available from Precision Weld located at 4701 Beam Road, Charlotte, N.C. 28217. The homogenous mixer is used in general extrusion applications to equal out color and temperature variations in the extrudant or melt. This is accomplished by stationary fins in the mixer which fold the extrudant to mix the extrudant. In the application of the present invention, a smaller number of fins are used than in the general usage of a homogenous mixer. By reducing the number of fins, the extrudant or mixture  222  has the segmented appearance of  FIG. 5  instead of a homogeneous appearance. In one embodiment, the homogenous mixture has 9 fins for general applications. To produce the segmented appearance of plastic extrudant  222 , fewer than 9 fins are used. In preferred embodiments, 7 to 8 fins are used to segment plastic extrudants  210  and  214 . In one preferred embodiment, 7 fins are used to segment plastic extrudants  210  and  214 . 
   Plastic extrudant or mixture  222  upon exiting segmentor  220  is presented to a turbulator  230  which expels a plastic extrudant or mixture  232  which is presented to co-extrusion block  206 . Plastic extrudant or mixture  232  enters co-extrusion block  206  in a separate channel from plastic extrudant  204 . The channel containing plastic extrudant or mixture  232 , in one embodiment, is above the channel containing plastic extrudant  206  such that second layer  120  is on top of first layer  110  in plastic sheet  100 . In another embodiment, the channel containing plastic extrudant or mixture  232 , is below the channel containing plastic extrudant  204  such that second layer  120  is below first layer  110  in plastic sheet  100 . In yet another embodiment, extrudant or mixture  232  is fed into two channels in co-extrusion block  206  such that plastic sheet  100  is comprised of three layers, a base layer including plastic extrudant  204  and a top and bottom layer including plastic extrudant or mixture  232 . Plastic extrudants  204  and  232  exit co-extrusion block  206  as plastic extrudant  236  and are fed to a sheet die  234 . Die  234  produces plastic extrudant  238  which is rolled into sheet  100  by rollers  240 . 
   Plastic sheet  100  is molded into an article for use by an end user. Examples include accessories for outdoor play equipment, such as slides, hunting accessories, such as gun cases, or canoes. 
   Referring to  FIG. 6 , turbulator  230  includes a housing  240  defining an interior region  241 , a first end  242 , a second end  244 , and an orientation unit  246 . A turbulator  230  is available from Precision-Weld located at 4701 Beam Road, Charlotte, N.C. 28217. However, the turbulator available from Precision-Weld must be modified in accordance with the present invention to produce plastic extrudant or mixture  232  and hence plastic sheet  100 . 
   Referring to  FIG. 7 , orientation unit  246  includes a shaft  248  and projections or fins  250  extending radially from an outer surface  252  in shaft  248 . The projections  250  and shaft  248  rotate along a central axis  251  of turbulator  230  due to the movement of plastic extrudant  222  in direction  223 . As shaft  248  rotates, projections  250  engage plastic extrudant  222  and cause plastic extrudant  222  to rotate. 
   Second end  244  of turbulator  230  includes a plate or selection member  254  containing a plurality of outlets  256  and a thrust bearing  258  interposed between plate  254  and shaft  248 . Thrust bearing  258  assists in the rotation of shaft  248 , projections  250  and plastic extrudant or mixture  222 . In alternative embodiments, additional forms of bearings are used. 
   In one exemplary embodiment, thrust bearing  258  is comprised of a first bearing  260  and a second bearing  262 . Both first bearing  260  and second bearing  262  are positioned within a recess  264  in plate or selection member  254 . First bearing  260  is positioned next to an arcuate surface  266  of recess  264 . Second bearing  262  is positioned between first bearing  260  and an arcuate surface  268  of shaft  248 . First bearing  260  and second bearing  262  contact each other and pivot independent of each other. In a preferred embodiment, first bearing  260  and second bearing  262  are spherical and are 0.34″ in diameter. 
   Referring to  FIGS. 7 and 8 , the plurality of outlets  256  extend from a first surface  270  of plate or selection member  254  located adjacent the interior region  241  of turbulator  230  through plate or selection member  254  to a second surface  272  of plate or selection member  254 . The plurality of outlets  256 , permit portions of plastic extrudant  222  to be expelled from turbulator  230  as plastic extrudant  232 . In one embodiment, plastic extrudant  222  is rotated relative to the plurality of outlets, to selectively expel portions of plastic extrudant  222  at various points in time. In another embodiment, the plurality of outlets are rotated due to the rotation of the selection member, to selectively expel portions of plastic extrudant  222  at various points in time. 
   Referring to  FIG. 8 , the plurality of outlets  256  are spaced around end plate  254 . The size, shape and locations of the plurality of outlets are some factors which dictate the portions of plastic extrudant  222  which are expelled from turbulator  230  to produce the pattern of plastic extrudant  232 . Additional factors include the rate of rotation of plastic extrudant  222 , and the flow rate of plastic extrudant  222 . In a preferred embodiment, plastic extrudant  222 , shaft  248  and projections  250  rotate at approximately 1 rpm. 
   In one embodiment, plate  245  has an outer diameter  280  of 4.235 inches. The second surface  272  continuing the plurality of outlets  256  is ring shaped with an inner diameter  282  of 1.500 inches and an outer diameter  284  of 3.500 inches. The plurality of outlets  256  includes a plurality of first outlets  286  having a circular cross section having a diameter  288  of 0.5625 inches and being centered 1.125 inches from the central axis  251  of turbulator  230 . The plurality of outlets further includes a plurality of second outlets  290  having a circular cross section having a diameter  292  of 0.3125 inches and being centered 1.3125 inches from the central axis  251  of turbulator  230 . 
   Referring to  FIG. 9 , the operation of turbulator  230  is illustrated for a partial rotation of shaft  248 , projections  250  and plastic extrudant  222 . Plastic extrudant  222  is positioned in turbulator  230  and is being oriented in time due to the rotation of shaft  248  and projections  250 . 
   With reference to  FIG. 9  the portions of plastic extrudant  222 , refer to a cylindrical column of plastic extrudant  222  extending back into turbulator  230 . As such, when it is stated that a particular portion has been expelled from turbulator  230 , in reality only a portion of the particular portion has been expelled. Additionally, each particular portion may contain a variety of appearances at various instances of time due to the types of plastic, extrudants  210  and  214 , which comprise that particular portion. The types of plastic, extrudants  210  and  214 , which comprise various portions of a particular portion is governed by a number of factors including the operational parameters of extruders  208  and  212 , the operational parameters of segmentor  220  including the number of fins used, and the operational parameters of turbulator  230 , including the rate of rotation of the shaft  248 . The preferred rates to produce a green camouflage and an arid camouflage are provided above. 
   Once the process is running at generally constant rates and parameters, the portions of plastic extrudant expelled from turbulator  230 , repeat every revolution of plastic extrudant  222  to form multiple instances of swirl pattern  153  in second layer  120 . As such, the swirl pattern  153  in plastic sheet  100  repeats itself along a length  173  of second layer  120 . In one embodiment, swirl pattern  153  repeats itself 3.5 times along length  173  when second layer  120  has a length of 100 inches and a thickness of 0.25 inches. 
   Referring to  FIG. 9 , at a first instance in time a first portion  300  of plastic extrudant  222  is oriented or positioned within the extent of first outlet  286   a  and a second portion  302  of plastic extrudant  222  is oriented or positioned outside the extent of both first outlets  286  and second outlets  290 . As such at a first instance of time, first portion  300  is expelled from turbulator  230  through first outlet  286   a  and second portion  302  is not expelled. 
   At a second instance in time, first portion  300  and second portion  302  have been rotated to second locations indicated by reference numerals  300 ′ and  302 ′. At the second instance in time, first portion  300 ′ is oriented or positioned outside the extent of first outlets  286  and second outlets  290  and second portion  302 ′ is oriented or positioned within the extent of first outlet  286   a . As such, at the second instance in time, first portion  300 ′ is not expelled from turbulator  230  and second portion  302 ′ is expelled through first outlet  286   a.    
   At a third instance in time first portion  300 ′ and second portion  302 ′ have been rotated to third locations indicated by reference numerals  300 ″ and  302 ″. At the third instance in time, first portion  300 ″ is oriented or positioned within the extent of second outlet  290   a  and second portion  302 ″ is oriented or positioned within the extent of first outlet  286   a . As such, at the third instance in time, first position  300 ″ and second portion  302 ″ are both being expelled from turbulator  230  through second outlet  290   a  and first outlet  286   a , respectively. 
   At a later instance of time first portion  300 ″ and second portion  302 ″ return to their positions in the first instance of time such that the first portion is oriented or positioned within the extent of first outlet  286   a  and the second portion is oriented or positioned outside the extent of both first outlets  286  and second outlets  290 . At the later instance of time a complete instance of pattern  153  has been expelled from turbulator  230  and a second instance of pattern  153  is beginning to be expelled from turbulator  230 . 
   In an alternative embodiment, a single layer sheet  400  having a pattern generally identical to pattern  153  is produced. Referring to  FIG. 10 , an exemplary embodiment  402  of the apparatus and process for manufacturing plastic sheet  400  is shown. The components used and method of operation of embodiment  402  is generally identical to embodiment  200 , shown in FIG.  3 . As such, like numerals will be used for similar components and extrudants in embodiments  402  and  200 . Details concerning the similar components and extrudants are provided in the detailed description of embodiment  200 . 
   Referring to  FIG. 10 , the mixture  232  exits turbulator  230  and is presented to die  404 . Die  404  produces plastic extrudant  406  which is rolled into sheet  400  by rollers  240 . The pattern formed in sheet  400  is generally identical to pattern  153  formed in sheet  100 , except that the pattern of sheet  400  is visible both through an outer or top surface and a bottom surface due to the absence of an opaque base layer. 
   While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.