Abstract:
A composite structure having a fibrous mat with perforated film coverings vacuumed formed on both sides of the fibrous mat. The composite structure is affixed between a structural foam and a soft foam to create a component part for use in applications such as automotive trim parts.

Description:
BACKGROUND 
     The present invention generally relates to mats of fibrous materials, and in particular to laminates of fibrous mats with perforated film coverings. 
     Fibrous mats are used in various applications such as in the construction of automotive trim parts. Prior technology formed the fibrous mats for automotive trim by spraying adhesives onto chopped fiberglass roving. The adhesive bonds the fiberglass together and to substrates. Different layers of fiberglass, foams, adhesives, and other materials were stacked together by hand to construct a sandwich, which is then formed into a biscuit and used for the production of the finished trim part. 
     However, the use of the prior art fibrous mats required many steps and excessive labor to produce the biscuit for use in the automotive trim parts. Therefore, there is a need for fibrous mats that can be used for the formation of multiple layer structure with fewer steps and less labor. Additionally, there is need for a fibrous mat for use in forming a multiple layer structure that has a lower weight, good thermoformability, good acoustical properties, and improved stiffness. 
     SUMMARY 
     In one embodiment, the present invention is a composite structure generally including a fibrous mat, a first film covering, and a second film covering. The fibrous mat has a mat first side and a mat second side, and formed from a plurality of fibers such that a plurality of passages are formed therein. The first film covering is disposed on the mat first side of the fibrous mat, and has a plurality of first film protrusions with first film apertures that extend into the plurality of passages in said fibrous mat. The second film covering is disposed on the mat second side of said fibrous mat and has a plurality of second film protrusions with second film apertures that extend into the plurality of passages in said fibrous mat. 
     In another embodiment, the present invention is a composite structure including a fibrous mat having a mat first side and a mat second side, and an adhesive film covering disposed on the mat first side of said fibrous mat. The fibrous mat is formed from a plurality of fibers such that a plurality of passages are formed therein. The adhesive film covering has a plurality of adhesive film protrusions with adhesive film apertures that extend into the plurality of passages in the fibrous mat. 
     In yet another embodiment, the present invention is a composite structure including a fibrous mat having a mat first side and a mat second side, and a multi layer film covering disposed on the mat first side of said fibrous mat. The fibrous mat is formed from a plurality of fibers such that a plurality of passages are formed therein. The multi layer film covering includes a plurality of multi layer film protrusions with multi layer film apertures, the plurality of multi layer film protrusions extending into the plurality of passages in said fibrous mat. 
     In yet another embodiment, the present invention is a process for forming a composite structure including the steps of providing a fibrous mat having a mat first side and a mat second side; placing the mat second side of the fibrous mat on a first perforated screen; disposing a first film covering material on the first side of the fibrous mat disposed on the first perforated screen; applying a vacuum to the back side of the first perforated screen with the fibrous mat and first film covering material disposed thereon to form a first film covering on the first side of the fibrous mat; placing the fibrous mat onto a second perforated screen with the first film covering adjacent to the second perforated screen; and, disposing a second film covering material onto the second side of the fibrous mat disposed on the second perforated screen; applying a vacuum to the back side of the second perforated screen with the first film covering, the fibrous mat, and the second film covering material disposed thereon to form a second film covering on the second side of the fibrous mat. 
     In yet another embodiment, the present invention is a process for forming a composite structure including the steps of providing a fibrous mat having a mat first side and a mat second side; placing the mat second side of the fibrous mat on a first perforated screen; coextruding a multiple layer first film covering material on the first side of the fibrous mat disposed on the first perforated screen; and, applying a vacuum to the back side of the first perforated screen with the fibrous mat and first film covering material disposed thereon to form a first film multiple layer covering on the first side of the fibrous mat. 
     In yet another embodiment, the present invention is a composite part including a composite mat structure and a foam layer. The composite mat structure includes a fibrous mat having a mat first side and a mat second side, a first film covering disposed on the mat first side of said fibrous mat, a second film covering disposed on the mat second side of said fibrous mat. The fibrous mat of the composite mat structure is formed from a plurality of fibers such that a plurality of passages are formed therein. The first film covering of the composite mat structure has a plurality of first film protrusions with first film apertures, the plurality of first film protrusions extending into the plurality of passages in the fibrous mat. The second film covering of the composite film structure includes a plurality of second film protrusions with second film apertures, the plurality of second film protrusions extending into the plurality of passages in the fibrous mat. The foam layer adheres to the first film covering of said composite mat structure. In a further embodiment, the present invention the first film covering is a multi layer film having a first external adhesive layer adjacent to said first foam layer. In another further embodiment, the present invention includes a second foam layer adhered to the second film covering of the composite mat structure. In yet a further embodiment, the second film covering is a multi layer film having an second external adhesive layer adjacent to the second foam layer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an enlarged partial cross section of a laminate illustrating an embodiment of the present invention 
     FIG. 2 is an enlarged partial perspective view of the laminate from FIG. 1; 
     FIG. 3 is an enlarged partial cross section of another embodiment of the laminate from FIG. 1; 
     FIG. 4 is an enlarged partial cross section of yet another embodiment of the laminate from FIG. 1; 
     FIG. 5 is schematic view of one embodiment of a process for forming the laminate of the present invention; 
     FIG. 6 is a more detailed schematic of the first film covering forming station from the process in FIG. 5; 
     FIG. 7 is a more detailed schematic of the second film covering forming station from the process in FIG. 5; and, 
     FIG. 8 is a partial perspective view of a component part made according to the present invention with the composite structure from FIG.  4 . 
    
    
     DETAILED DESCRIPTION 
     Referring now to the figures, and in particular to FIGS. 1-4, there is disclosed an embodiment of the present invention illustrated as the composite structure  10 . The composite structure  10  generally comprises a fibrous mat  100  with a mat first side  110  and a mat second side  120 , a first film covering  200  disposed on the mat first side  110 , and a second film covering  300  disposed on the mat second side  120 . The first film covering  200  includes first film protrusions  210  extending into the fibrous mat  100  and first film perforations  220 . The second film covering  300  includes second film protrusions  310  extending into the fibrous mat  100  and second film perforations  320 . 
     The fibrous mat  100  is formed of a plurality of synthetic or natural fibers  130  such as fiberglass, sisal, polymeric fibers, excelsior, combinations thereof, or the like. The fibers  130  in the fibrous mat  100  are arranged such that mat openings/passages  140  are formed in the fibrous mat  100 . The mat opening/passages  140  in the fibrous mat  100  provide an open area in the fibrous mat  100  between the mat first side  110  and mat second side  120 . In one embodiment, the fibrous mat  100  includes a binder  150  that holds together the fibers  130  in the fibrous mat  100 . 
     The characteristics of the fibrous mat  100 , such as stiffness, thickness, and/or open area, are selected based upon the contribution of the fibrous mat  100  to the criteria of the composite structure  10 , such as stiffness and sound deadening. In one preferred embodiment, the fibrous mat  100  has a thickness of from about 10 mils to about 25 mils and an open area of from about 10% to about 50% open area. 
     The parameters of the components of the fibrous mat  100 , such as the fibers  130  and the binder  150 , determine the characteristics of the fibrous mat  100 . For example, the density, diameter, size, and modulus of elasticity of the fibers  130  will contribute to the stiffness and open area properties of the fibrous mat  100 . The binder  150  will also contribute to the stiffness and open area of the fibrous mat  100 . 
     The first film covering  200  adheres to the fibers  130  exposed on the mat first side  110  of the fibrous mat  100 . In a preferred embodiment, the first film covering  200  encapsulates some of the fibers  130  on the mat first side  110 . The first film protuberances  210  extend through the mat first side  110  into the mat opening/passages  140  of the fibrous mat  100 . The first film perforations  220  are formed at the end of the first film protuberances  210 . 
     Similar to the first film covering  200 , the second film covering  300  adheres to the fibers  130  exposed on the mat second side  120  of the fibrous mat  100 . In a preferred embodiment, the second film covering  300  encapsulates some of the fibers  130  on the mat second side  120 . The second film protuberances  310  extend into the mat openings/passages  140  on the mat second side  120  of the fibrous mat. The second film perforations  320  are formed in the end of the second film protuberances  310  of the second film covering  300 . 
     The extension of the first film protuberances and the second film protuberances  310  into the fibrous mat  100 , inhibit the individual fibers  130  from escaping through the first film perforations  220  and the second film perforations  320 , should those individual fibers become loose from the fibrous mat  100 . Additionally, at various points in the fibrous mat  100 , the first film perforations  220  may even join with the second film perforations  320  to form a passageway from the first film covering  200  to the second film covering  300 . 
     The material of the first film covering  200  and the second film covering  300  is selected based upon the desired characteristics that the respective film covering will provide the composite structure  10 . In one embodiment, the first film covering  200  and/or the second film covering  300  provides stiffness to the composite structure by using a thermoplastic material. Examples of thermoplastic materials that can be used in the present invention include high density polyethylene (HDPE), nylon, polyester, polypropolyene, polystyrene, polycarbonate, combinations thereof, or the like. Additionally, the material of the first film covering  200  and/or second film covering  300  can be filled to improve stiffness, with materials such as calcium carbonate, talc, clay, or other common filler materials. 
     In another embodiment, the first film covering  200  and/or the second film covering  300  is formed from an adhesive material to facilitate bonding of the composite structure  10  to other structures. Examples of adhesive materials that can be used in the present invention include copolymers of ionomers, ethylene acrylic acid (EAA), ethylene methyl acrylic acid (EMAA), ethylene vinyl acetate (EVA), ultra low density polyethylene (ULDPE), ethyl methyl acrylate (EMA), combinations thereof, or the like. 
     In yet another embodiment, the first film covering  200  and/or the second film covering  300  is a co-extrusion of two or more layers of various materials, as shown in FIGS.  3  and  4 . For example, as shown in FIG. 3, the second film covering  200  can be a co-extrusion having a first film high density polyethylene layer  200   a  adjacent to the fibrous mat  100  to provide structural rigidity, and a first film adhesive material layer  200   b  on the opposing side to facilitate bonding of the composite structure  10 . The co-extrusion of a material such as high density polyethylene between an adhesive layer and the fibrous mat  100  prevents the migration of the adhesive layer into the fiber material. In another example, as illustrated in FIG. 4, the second film covering  300  is also a co-extrusion having a second film high density polyethylene layer  300   a  adjacent to the fibrous mat  100  to provide structural rigidity, and a second film adhesive material layer  300   b  on the opposing side to facilitate bonding of the composite structure  10 . 
     A part of the present invention is the unexpected additional stiffness of the composite structure  10 . The completed composite structure has a stiffness greater than the stiffness of the fibrous mat  100 , the first and second film coverings  200  and  300 , or the expected stiffness of the combination of the fibrous mat  100 , the first film  200 , and the second film  300 . 
     Referring now to FIGS. 5-7, there shown one embodiment of a process for forming the composite structure  10  from FIGS. 1-4, illustrated as the forming process  600 . The forming process  600  generally includes a fibrous mat supply  610 , a first film covering forming station  620 , a second film covering forming station  630 , a corona treating station  640 , and a composite take up  650 . 
     The fibrous mat  100  proceeds from the fibrous mat supply  610  to the first film covering forming station  620 . At the first film covering forming station  620 , the fibrous mat proceeds over a first vacuum screen  621 . The first vacuum screen  621  includes a plurality of first vacuum screen apertures  622 . A first extruder  623  extrudes a first film material  624  onto the fibrous mat  100  disposed on the first vacuum screen  621 . A first vacuum source  625  behind the first vacuum screen  621  draws the first film materials  624  into the fibrous mat  100  forming the first film covering  200  with the first film protuberances  210  and the first film perforations  220  extending into the mat openings/passages  140 . In one embodiment, the vacuum source  625  can provide a vacuum of about 20 inches of mercury or less, and preferably between about 10 to about 15 inches of mercury. 
     The fibrous mat  100  with the first film covering  200  thereon proceeds from the first film covering forming station  220  to the second film covering forming station  630 . At the second film covering forming station  630 , the fibrous mat  100  and the first film covering  200  are disposed on a second vacuum screen  631  with the first film covering  200  engaging the second vacuum screen  631 . The second vacuum screen  631  includes a plurality of second vacuum screen apertures  632 , such that at least a portion of the second vacuum screen apertures align with the first film perforations  220  in the first film covering  200 . A second extruder  633  extrudes a second film material  634  onto the mat second side  120  of the fibrous mat  100 . A second vacuum source  635  behind the second vacuum screen  621  draws the second film material  634  into engagement with the second mat side  120  of the fibrous mat  100  such that the second film material  634  encapsulates fibers  130  on the mat second side  120  of the fibrous mat, and extends into the mat openings/passages  140  on the mat second side  120  to form the second film protuberances  130  and the second film perforations  320  of the second film covering  300 . In one embodiment, he vacuum source  635  can provide a vacuum of about 20 inches of mercury or less, and preferably between about 10 to about 15 inches of mercury. 
     Although FIG. 5 is illustrated as a continuous single process, the present invention can be practice performing the application of the first film covering in a first process, and performing remaining steps in a second separate process. After the second film covering is formed on the fibrous mat  100 , the composite structure  10  progresses to a corona treatment station  640 , if corona treatment is desired on the final product. After final processing, the composite structure  10  is collected on the composite take up  650 . 
     In addition to the previously mentioned criteria for selecting material of the fibrous mat  100 , is the ability of the material of the fibrous mat  100  to be used in the forming process  600  of the composite structure  10 . The fibrous mat  100  must be flexible enough to pass over the first and second vacuum screens  621  and  631 , as well as the other equipment in the forming process  600 . Also, the open area of the fibrous mat  100  the viscosity of the first and second film materials  624  and  634  must be sufficient that the first and second film materials  624  and  634  pull into the material of the fibrous mat  100  for aperturing. In one preferred embodiment, the first and second film materials  624  and  634  have a melt index of from about 10 to about 20, preferably about 18. 
     The open area of the first vacuum screen  621  is selected to provide the highest probability of the first vacuum screen aperture  622  aligning with mat openings/passages  140  in the fibrous material  100 , to facilitate the securing of the first film covering  200  on the fibrous mat  100 . In one embodiment, the fibrous mat  100  had an open area of approximately 50%, the open area of the first vacuum screen  621  was from about 60% to about 70%, resulting in an open area of the combination of the fibrous mat  100  with the first film covering  200  of about 15%. 
     The open area of the second vacuum screen  631  is selected to provide the highest probability of the second vacuum screen aperture  632  aligning with the first film perforations  222  in the first film covering. In one embodiment, the second vacuum screen  631  has an open area of from about 60% to about 70%, and was used on the combination of a fibrous mat  100  with a first film covering  200  having an open area of about 15%, which resulted in the combination of the fibrous mat  100  with the first film covering  200  and the second film covering  300  having an open area from about 1% to about 10%. 
     The above method was used to produce the following examples of the present invention: 
     EXAMPLE 1 
     A JOHNS MANVILLE 8440 fiberglass mat is coated on each side with a high density polyethylene (HDPE) blend film having a weight per area of forty (40) grams per square meter. The HDPE blend includes seventy percent (70%), by weight, of EQUISTOR H6018 (HDPE) and thirty percent (30%), by weight, of DOW 2517 (LDPE) and is about 1.5 mils. thick. 
     EXAMPLE 2 
     A JOHNS MANVILLE 8450 fiberglass mat is coated on both sides by a laminate film. The laminate film has a first layer of HDPE blend disposed adjacent to the fiberglass mat, and a second layer of adhesive blend disposed on the side of the laminate opposite to the fiberglass mat. The first layer is a 0.25 mil. layer of an HDPE blend of seventy percent (70%), by weight, of EQUISTOR H6018 and thirty percent (30%), by weight, of DOW 2517. The second layer is a 1.25 mil. layer of an adhesive blend of seventy-five percent (75%), by weight, of DUPONT BYNEL 2022 (EMA copolymer) and twenty-five percent (25%), by weight, of DUPONT SURLYN 1855 (zinc ionomer). 
     EXAMPLE 3 
     A JOHNS MANVILLE 8440 fiberglass mat is coated on a first side with a HDPE blend film, and on a second side with a adhesive blend film. The HDPE blend film is a 2.5 mil. film of a blend of seventy percent (70%), by weight, of EQUISTOR H6018 and thirty percent (30%), by weight, of DOW 2517. The adhesive blend film is a 1.0 mil. film of a blend of fifty-two and one-half percent (52.5%), by weight, of DUPONT 2022, seventeen and one-half percent (17.5%), by weight, of DUPONT 1855, and thirty percent (30%), by weight, of DOW 2517. 
     EXAMPLE 4 
     A JOHNS MANVILLE 8440 fiberglass mat is coated on both sides with a 1.5 mil. polypropolyene blend film. In this embodiment, the polypropolyene blend is a blend of seventy percent (70%), by weight, of FINA 6573 (PP), twenty-two and one-half percent (22.5%), by weight, of DUPONT 2022, and seven and one-half percent (7.5%) of DUPONT 1855. 
     Referring now to FIG. 8, there is shown an embodiment of an invention utilizing the composite material in FIGS. 1-4, illustrated as the component structure  800 . The component part  800  generally includes the composite structure  10 , a structural foam  820 , and a soft foam  830 . The composite structure  10  is of the type having an adhesive layer  200   b  and  300   b  disposed outwardly from the fibrous mat  100 , as shown in FIG.  4 . 
     The component part  800  is formed by thermally activating the adhesive layers  200   b  and  300   b  on the composite structure  10 , and affixing the structural foam  820  and the soft foam  830  to opposite sides of the composite structure  10 . The component part  800  can be molded into a shape to accommodate the application of the component part  800  such as for a head liner in an automobile. 
     Use of the fibrous mat  10  with adhesive layers  200   b  and  300   b,  eliminates the need for an adhesive sheet between the fibrous mat and the structural foam  820  or the soft foam  830 . Additionally, a part of the present invention is the discovery that the use of the composite structure  10  with the protuberances  210  and  310  and the perforations  220  and  320 , provide unexpected additional acoustic attenuation properties the component part  800 .