Abstract:
A method for joining two carpet segments, each carpet segment having an underside and at least one edge. The method comprises abutting one edge of one carpet segment with one edge of the other carpet segment; positioning a length of seam tape under the abutting edges, and activating the adhesive to secure the seam tape to the undersides of both carpet segments. The seam tape comprises an elongated base layer that is resilient in a transverse direction and an adhesive applied to the base layer. The adhesive may comprise a hot-melt thermoplastic adhesive. The base layer may comprise a resilient textile or fabric, such as cotton denim and elastane.

Description:
FIELD OF THE INVENTION 
     The present invention relates to carpet seam tape and methods for joining carpet. 
     BACKGROUND 
     When installing carpet, it is common for the room in which the carpet is being installed to have at least one dimension (length or width) that is greater than the length of a standard roll of carpet (which is typically twelve feet). In such a case, a single unitary segment of carpet from a roll cannot cover the entire floor of the room, and two or more segments must be pieced together. When two or more segments are pieced together, an edge of one segment is abutted against an edge of another segment, and these edges are joined (“seamed”) together using seam tape. 
       FIGS. 1 and 2  illustrate top and cross-sectional views, respectively, of prior art seam tape. Prior art seam tape  10  comprises an elongated base layer  12 , scrim  14 , and an adhesive  16  (the adhesive is omitted from  FIG. 1  for clarity). The base layer typically comprises paper or other relatively inelastic material. The scrim typically comprises woven threads and provides strength and additional inelasticity to the seam tape. The adhesive typically comprises a hot-melt thermoplastic adhesive applied to a large portion of the base layer. The scrim is embedded within the adhesive. 
     When joining carpet edges together, the edge of one carpet segment is positioned to abut the edge of the other carpet segment. The seam tape is positioned under the abutting edges, and the adhesive is activated by applying heat to the top surface of the carpet above the seam tape. The heat melts the adhesive and the melted adhesive bonds to the underside of both carpet segments as the adhesive cures. 
     After the carpet segments are positioned to cover the entire floor and the seams are joined using seam tape, the carpet is stretched at the outer edges and the outer edges are secured to the floor using tack strips. The stretching tightens the carpet to remove any slack and wrinkles  FIG. 3  illustrates what happens when the carpet is stretched in a direction transverse to the carpet seam (indicated by the arrows in  FIG. 3 ). The top image of  FIG. 3  illustrates the unstretched carpet. As the carpet is stretched and the two carpet segments  18 A,  18 B are pulled away from each other, the inelasticity of the seam tape  10  causes the seam to lift off the floor, resulting in an unsightly bulge in the carpet (illustrated in the bottom image of  FIG. 3 ). This is called seam “peaking” or “profiling” and is highly undesirable. 
     BRIEF SUMMARY 
     In one embodiment of the invention, a method for joining two carpet segments, each carpet segment having an underside and at least one edge, comprises abutting one edge of one carpet segment with one edge of the other carpet segment; positioning a length of seam tape under the abutting edges, the seam tape comprising an elongated base layer being resilient in a transverse direction; and an adhesive applied to the base layer; and activating the adhesive to secure the seam tape to the undersides of both carpet segments. 
     In another embodiment of the invention, a method for joining two carpet segments, each carpet segment having an underside and at least one edge, comprises abutting one edge of one carpet segment with one edge of the other carpet segment; positioning a length of seam tape under the abutting edges, the seam tape comprising an elongated base layer comprising fabric; and an adhesive applied to the base layer; and activating the adhesive to secure the seam tape to the undersides of both carpet segments. 
     In another embodiment of the invention, a method for joining two carpet segments, each carpet segment having an underside and at least one edge, comprises abutting one edge of one carpet segment with one edge of the other carpet segment; positioning a length of seam tape under the abutting edges, the seam tape comprising an elongated base layer; and an adhesive applied to the base layer; and activating the adhesive to secure the seam tape to the undersides of both carpet segments. In this embodiment, the seam tape does not comprise a scrim. 
     In any of the above methods, the adhesive may comprise a hot-melt thermoplastic adhesive, and the base layer may comprise fabric, such as cotton and elastane or denim and elastane. In any of the above methods, the adhesive may comprise (a) a unitary mass of adhesive, (b) a plurality of beads of adhesive, or (c) a plurality of spots of adhesive. 
     In another embodiment of the invention, carpet seam tape for joining two carpet segments comprises an elongated base layer being resilient in a transverse direction; and an adhesive applied to the base layer. 
     In another embodiment of the invention, carpet seam tape for joining two carpet segments comprises an elongated base layer comprising fabric; and an adhesive applied to the base layer. 
     In another embodiment of the invention, carpet seam tape for joining two carpet segments comprises an elongated base layer; and an adhesive applied to the base layer. However, the seam tape does not comprise a scrim. 
     In any of the above carpet seam tapes, the adhesive may comprise a hot-melt thermoplastic adhesive, and the base layer may comprise fabric, such as cotton and elastane or denim and elastane. In any of the above methods, the adhesive may comprise (a) a unitary mass of adhesive, (b) a plurality of beads of adhesive, or (c) a plurality of spots of adhesive. 
     In another embodiment of the invention, a carpet system comprises two carpet segments; and carpet seam tape affixed to and joining the two carpet segments. The carpet seam tape comprises an elongated base layer being resilient in a transverse direction; and an adhesive applied to the base layer. 
     In another embodiment of the invention, a carpet system comprises two carpet segments; and carpet seam tape affixed to and joining the two carpet segments. The carpet seam tape comprises an elongated base layer comprising fabric; and an adhesive applied to the base layer. 
     In another embodiment of the invention, a carpet system comprises two carpet segments; and carpet seam tape affixed to and joining the two carpet segments. The carpet seam tape comprises an elongated base layer; and an adhesive applied to the base layer. However, the seam tape does not comprise a scrim. 
     In any of the above carpet systems, the adhesive may comprise a hot-melt thermoplastic adhesive, and the base layer may comprise fabric, such as cotton and elastane or denim and elastane. In any of the above methods, the adhesive may comprise (a) a unitary mass of adhesive, (b) a plurality of beads of adhesive, or (c) a plurality of spots of adhesive. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  is a top view of prior art seam tape; 
         FIG. 2  is a cross-sectional view of the prior art seam tape of  FIG. 1  along the indicated line; 
         FIG. 3  illustrates carpet segments joined using the prior art seam tape of  FIG. 1 ; 
         FIG. 4  is a top view of seam tape, in accordance with an embodiment of the present invention; 
         FIG. 5  is a cross-sectional view of the seam tape of  FIG. 4 ; 
         FIG. 6  illustrates carpet segments joined using the seam tape of  FIG. 4 ; 
         FIG. 7  is a top view of seam tape, in accordance with an alternative embodiment of the present invention; and 
         FIG. 8  is a cross-sectional view of the seam tape of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the invention provide the ability to securely join carpet segments while preventing seam peaking when the joined carpet is stretched. Referring now to  FIGS. 4 and 5 , top and cross-sectional views are illustrated, respectively, of seam tape in accordance with an embodiment of the present invention. The seam tape  30  of embodiments of the invention comprises an elongated base layer  32  and an adhesive  36  applied to the base layer. Notably, the seam tape does not comprise a scrim. The elongated base layer may comprise any suitable material that is resilient (stretches and rebounds) in a transverse (perpendicular to the longitudinal axis) direction. For example, the elongated base layer may comprise a textile or fabric (including combinations of different textiles or fabrics), rubber, polymer (including combinations of different polymers), and combinations thereof. In one embodiment of the invention, the elongated base layer comprises a fabric that combines cotton (such as denim) and elastane (such as Lycra or Spandex). For example, the fabric that is used to make “stretch jeans” may be used for the base layer. Such a fabric may be, for example, 98% denim and 2% elastane or 95% denim and 5% elastane, although different amounts of denim and elastane may be used. Optionally, one or more additional materials may be combined with the cotton and elastane. For example, the elongated base layer may comprise a fabric that combines polyester with the cotton and elastane, such as a combination of 78% cotton denim, 18% polyester, and 4% elastane. The fabric may be dyed or undyed. The adhesive typically comprises a hot-melt thermoplastic adhesive. 
     The material selected for the elongated base layer should be as resilient as the carpet to which the seam tape is to be secured, such as to not impede the carpet from stretching. However, it may also be desirable for the material to not be significantly more resilient than the carpet. Such a material should provide enough stretch to the seam tape to reduce the likelihood of seam peaking, but not so much stretch as to allow a gap to be visible at the seam. As different types of carpets may have different amounts of resiliency, it may be desirable to have different types of seam tapes, each with a different amount of resiliency to match a different type of carpet. Alternatively, it may be desirable to have a single type of seam tape that has sufficient resiliency to be used with a wide variety of different types of carpet. 
     For purposes of this application, the terms “textile” and “fabric” are used interchangeably to refer to a flexible woven material comprising a network of natural or artificial fibers (often referred to as thread or yarn). Textiles are formed by weaving, knitting, crocheting, knotting, or pressing fibers together. For purposes of this application, the terms “textile” and “fabric” specifically exclude paper. 
       FIG. 6  illustrates what happens when carpet that is joined using carpet seam tape  30  of embodiments of the invention is stretched in a direction transverse to the carpet seam (indicated by the arrows in  FIG. 6 ). As the two carpet segments  38 A,  38 B are pulled away from each other, the elasticity of the seam tape  30  prevents the seam from lifting off the floor, thereby preventing seam peaking. It does this by allowing the stretch to “reach” the seam. That is, the portions of the carpet that are affixed to the seam tape (of embodiments of the invention) are able to stretch (along with the seam tape). In contrast, the prior art seam tape does not allow the portions of the carpet that are affixed to the prior art seam tape to stretch (because the prior art seam tape does not stretch). 
     Referring now to  FIGS. 7 and 8 , top and cross-sectional views are illustrated, respectively, of seam tape in accordance with an alternative embodiment of the present invention. The seam tape  50  of alternative embodiments of the invention comprises an elongated base layer  52  and an adhesive  56  applied to the base layer. As above, seam tape  50  does not comprise a scrim. Rather than a unitary mass of adhesive applied to the base layer, seam tape  50  comprises a plurality of “beads” of glue. The beads of glue are illustrated as being substantially parallel to the longitudinal axis of the seam tape and to each other, but other configurations may be used. The beads are illustrated as being continuous, but may be non-continuous beads or may even comprise individual “dots” or “spots” of adhesive. Such a non-unitary application of adhesive to the base layer may be desirable where a non-flexible (or insufficiently flexible) adhesive is used. Some types of adhesives, once cured, may be less flexible than other types of adhesives. For example, high melt glue is less flexible, once cured, than low melt glue. Using a non-unitary application of adhesive to the base layer when a less flexible adhesive is used prevents (or at least reduces) the adhesive from restricting the tape (and therefore the carpet) from stretching. 
     While four beads of adhesive are illustrated in  FIGS. 7 and 8 , the amount of adhesive in each bead and the spacing and number of the beads may vary, depending on the type of adhesive, the type of carpet, etc. It is desirable that the amount of adhesive and the spacing of the beads be selected such that the beads remain separate and do not run together when the seam tape is heated and the adhesive is melted. Since the use of such beads is typically limited to glues that are relatively less flexible, ensuring that the beads remain separate after melting helps maintain the continued resiliency of the seam tape. 
     The carpet seam tape of embodiments of the invention offers many improvements over prior art seam tape. The carpet seam tape of embodiments of the invention lays flat despite stretching of the carpet because the elasticity of the seam tape allows the carpet to stretch. The carpet seam tape of embodiments of the invention is easier to manufacture and less expensive due at least to the lack of a scrim. The carpet seam tape of embodiments of the invention provides a bond that is better capable of withstanding repeated steam cleaning due to its use of fabric rather than paper as the base layer. 
     When the carpet seam tape of embodiments of the invention is used to seam carpet, the edges of the carpet should be “seam sealed” as per standard carpet seaming practices established by the Carpet and Rug Institute. This seam sealing step further reduces the likelihood of peaking. It is anticipated that all other standard seaming techniques will work when the carpet seam tape of embodiments of the invention is used to seam carpet, and therefore should be used. 
     In addition to joining carpet segments during installation of carpet, the carpet seam tape of embodiments of the invention may be used in a carpet mill to join the ends of carpet rolls to form larger carpet rolls. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.