HK1260205B - Pressure-sensitive pvc cover strip - Google Patents

Description

Pressure-sensitive PVC cover tape

Background Art

In the roofing industry, cover strips are commonly used to join two materials together, such as edge strips and roofing membranes. Typically, these are 6 to 9 inch wide membrane strips coated with a pressure-sensitive adhesive layer. Traditional PVC roofing membranes contain liquid phthalate plasticizers, which will attack many traditional pressure-sensitive (PS) adhesives in the roofing market. Currently, no manufacturer offers a PS cover strip product for PVC roofs. This is problematic for handling edge metal. Currently, all edge metal used with PVC membrane roofs must be PVC coated to allow non-PS PVC flashing to be welded to the metal as well as the PVC roofing membrane. This limits the colors available for the metal. Finally, there is currently no simple way to overlap a PVC roofing membrane to an EPDM or TPO membrane without an edge trim between the two membranes.

Summary of the Invention

This invention provides a primer and PS adhesive system that allows for the production of PS/PVC cover strips that can be adhered to a variety of substrates, including PVC and KEEPVC membranes, metal trim, EPDM, and TPO roofing membranes. The proposed PS/PVC cover strips are constructed using a series of primers that allow common PS roof adhesives to be used with PVC membranes. The first primer provides a highly plasticizer-resistant layer. This prevents plasticizers from the PVC membrane from attacking the PS adhesive. The second primer prepares the PVC surface for PS adhesive bonding. The PS adhesive must be adequately formulated to accommodate sudden drops, provide long-term performance, resist waterlogging, and be compatible with other common single-ply roofing materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a cross-sectional view of a cover strip according to the present invention;

FIG2 is a cross-sectional view of a cover strip of the present invention for use with an edge terminal; and

3 is a partially exploded cross-sectional view illustrating the application of a cover tape to a PVC film and a non-PVC film.

DETAILED DESCRIPTION

As shown in FIG1 , the present invention is a cover strip 10 comprising an upper PVC layer 12, typically about 60 mils thick, of the type typically used for roofing applications. The bottom surface of the PVC layer 12 is coated with a barrier layer 14, which prevents migration of plasticizers from the PVC layer 12. The barrier layer 14 is in turn coated with a primer layer 16, which is in turn coated with a pressure-sensitive (PS) adhesive layer 18. Finally, the PS layer is covered with a silicone rubber-coated release sheet 20. The cover strip will be 6-12 inches wide, typically 6-9 inches wide.

The barrier layer 14 is a layer that prevents the migration of phthalate-type plasticizers commonly used in PVC films. Typically, the barrier layer will be a polar polymer. A polar polymer suitable for the present invention is acrylonitrile rubber or NBR, which is applied directly to the surface and PVC and allowed to solidify. Typically, this will be 0.167 mil to 2.5 mil thick.

The composition of the primer will be determined by the composition of the pressure-sensitive adhesive. Usually, the primer will be 0.2 mil to 0.6 mil thick. The pressure-sensitive adhesive can be any pressure-sensitive adhesive commonly used in roof applications, such as brominated butyl rubber, pressure-sensitive adhesive, etc. Other suitable pressure-sensitive adhesives can be based on butyl, polyisobutylene, halogenated butyl or other suitable polymers. Primer has a similar composition usually, but has a low solids content. Primer is simply applied to the isolation layer 14 and allowed to solidify. Then, the pressure-sensitive adhesive layer 18 and the separator 20 are laminated to the primer layer 16.

FIG2 illustrates the use of the present invention in applying a rigid edge member 30 to a roof surface 32 covered with a PVC membrane 34. In this application, the PVC membrane 34 is applied to the roof 32 as is typically done during roofing applications. Connecting strips 33 are nailed to the corners of the roof 32. The rigid edge member (edge termination strip) 30 is joined to the connecting strip 33 at one edge and nailed to the roof 32, thereby trapping the PVC membrane between the roof surface and the rigid edge member (edge treatment) 30. The rigid edge member (edge treatment) 30 in this application is not coated with a PVC coating, but rather may be a painted metal surface, etc. Essentially, any non-PVC coated edge treatment can be used in this application.

Covering strip 10 is applied over the rigid edge member (edge treatment) 30 and the PVC film 34. A strip barrier coating 36 and a primer coating 38, typically identical to barrier coating 14 (also identical to primer coating 16 in FIG. 1 ), are applied to the PVC film 34. Release sheet 22 is removed from cover strip 10 and cover strip 10 is applied over the barrier and primer-coated portions of the PVC 34 and directly onto the upper surface of the rigid edge member (edge treatment) 30. Sealant 42 may be applied to either edge of cover strip 10 to provide additional waterproof isolation, but is not required. Pressure-sensitive adhesive layer 18 will be bonded directly to the surface of the edge treatment using primer layer 38 and further bonded to the PVC 34 coated with a separate barrier layer 36 and a separate primer layer 38.

FIG3 illustrates another use of the present invention, in which a cover strip 10 is used to bond a PVC film 50 to a non-PVC film 52, such as TPO, EPDM, or the like. The edge 54 of the PVC film 50 is first coated with a strip of release layer 56 and subsequently with a primer layer 58. Since the non-PVC film 52 does not contain plasticizers, a release layer is not required. However, a strip of primer 58 is applied to the edge 62 of the film 52 to improve adhesion to the PSA. The cover strip 10 is simply applied directly to the edge portions of the two films. The pressure-sensitive adhesive 18 adheres to the primer layer 58 on the PVC layer and bonds directly to the surface of the non-PVC film 52. Furthermore, the pressure-sensitive adhesive on the cover strip is protected from the plasticizers present in the PVC. Furthermore, no welding is required to form any bond.

The present invention has been described in conjunction with the preferred method of carrying out the invention. However, the invention itself should only be defined by the appended claims.

Claims (11)

1. An edge treatment section for a roof, wherein the roof is coated with a PVC film, the edge treatment section comprising: A metal panel strip, which can be secured to the roof to extrude the PVC film between the metal panel strip and the roof; and Covering strips are used to bond the metal panel strips to the PVC film; The covering strip includes a PVC layer, the PVC layer having a bottom surface covered with an isolation layer that effectively prevents plasticizer migration; The isolation layer is coated with a pressure-sensitive adhesive layer, which is bonded to the metal panel strip and positioned on the cover strip to bond to the PVC film. 2. The edge treatment part according to claim 1, wherein the insulating layer is acrylonitrile rubber. 3. The edge treatment part as described in claim 1 or 2, wherein the pressure-sensitive adhesive is brominated butyl rubber. 4. The edge processing unit according to claim 1, wherein the isolation layer is 0.167 mil to 2.5 mil thick. 5. The edge treatment section according to claim 1, further comprising a primer layer located between the isolation layer and the pressure-sensitive adhesive layer, wherein the primer layer is 0.2 mil to 0.6 mil thick. 6. The edge treatment part according to claim 1, wherein the metal panel strip is L-shaped and is fixed to the edge of the roof. 7. The edge treatment section according to claim 1, further comprising a strip isolation coating on the PVC film and a primer coating layer on the strip isolation coating, wherein the pressure-sensitive adhesive layer covering the strip contacts the primer coating layer. 8. The edge treatment section according to claim 7, further comprising a primer layer located between the isolation layer and the pressure-sensitive adhesive layer of the cover strip. 9. The edge treatment section according to claim 1, wherein the pressure-sensitive adhesive layer extends from one edge of the cover strip where the pressure-sensitive adhesive layer is positioned to bond to the metal panel strip to the opposite edge where the pressure-sensitive adhesive layer is positioned to bond to the PVC film. 10. A roof surface comprising an edge treatment portion according to claim 1 fixed to the roof, wherein the PVC film is located between the roof and the edge treatment portion. 11. A roof surface comprising: A PVC film adjacent to a non-PVC film, wherein the PVC film is bonded to the non-PVC film by a cover strip; The covering strip includes a PVC layer, which is further coated with an insulating layer and a pressure-sensitive adhesive layer; and The edge portion of the PVC film is covered with an isolation layer, and both the edge portion of the PVC film and the edge portion of the non-PVC film are covered with a primer coating layer, and the pressure-sensitive adhesive layer is bonded to the primer coating layer on each edge portion.