Minimum visibility seam tape and method of joining substrates using the same

• US 5,906,696 A
• Filed: 07/29/1993
• Issued: 05/25/1999
• Est. Priority Date: 04/19/1991
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Company
• Inventors: Warner, Robert W., Nielsen, John A., Theissen, Richard F., Pontuti, James A.
• Primary Examiner(s): Gallagher, John J.
• Application Number:
  US08/099,220
• Time in Patent Office: 2,126 Days
• Field of Search: 156/304.3, 156/98, 156/304.4, 428/61, 428/63, 428/247, 40/603, 40/604
• US Class Current: 156/98
• CPC Class Codes: B29C 65/38 Impulse heating
• CPC Class Codes: B29C 65/4815 Hot melt adhesives, e.g. thermoplastic adhesives
• CPC Class Codes: B29C 65/5021 being multi-layered
• CPC Class Codes: B29C 65/5028 being textile in woven or non-woven form
• CPC Class Codes: B29C 65/5042 covering both elements to be joined
• CPC Class Codes: B29C 65/7847 using vacuum to hold at least one of the parts to be joined vacuum work holders in general B25B11/005
• CPC Class Codes: B29C 66/1142 Single butt to butt joints
• CPC Class Codes: B29C 66/43 Joining a relatively small portion of the surface of said articles B29C66/45 takes precedence
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/721 Fibre-reinforced materials B29C66/729 takes precedence
• CPC Class Codes: B29C 66/7392 characterised by the material of at least one of the parts being a thermoplastic
• CPC Class Codes: B29C 66/91411 of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• CPC Class Codes: B29C 66/9241 by controlling or regulating the pressure, the force or the mechanical power
• CPC Class Codes: B29C 66/929 characterized by specific pressure, force, mechanical power or displacement values or ranges
• CPC Class Codes: B29K 2023/04 Polymers of ethylene
• CPC Class Codes: B29K 2023/06 PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/10 Polymers of propylene
• CPC Class Codes: B29K 2023/12 PP, i.e. polypropylene
• CPC Class Codes: B29K 2027/06 PVC, i.e. polyvinylchloride
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2075/00 : Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2313/00 : Use of textile products or fabrics as reinforcement B29K2105/06 takes precedence
• CPC Class Codes: G09F 13/08 : using both translucent and non-translucent layers
• CPC Class Codes: G09F 7/00 : Signs, name or number plates, letters, numerals, or symbols vehicle registration number plates B60R13/10; Panels or boards show-cards G09F1/00; indicating arrangements for variable information G09F9/00, G09F11/00; illuminated signs G09F13/00; boards for notices or posters G09F15/00
• CPC Class Codes: Y10T 428/19 : Sheets or webs edge spliced or joined
• CPC Class Codes: Y10T 428/197 : with noncoplanar reinforcement
• CPC Class Codes: Y10T 428/20 : Patched hole or depression
• CPC Class Codes: Y10T 442/178 : Synthetic polymeric fiber
• CPC Class Codes: Y10T 442/198 : Coated or impregnated

Abstract

A minimum visibility seam tape and method of joining at least two substrates with the tape. The substrates joined typically are sign faces or awnings comprising a composite of thermoplastics and a woven scrim. The seam tape is a woven or nonwoven scrim embedded in or coated with a thermoplastic polymer.

Claims

1. A method of joining at least two translucent sign face substrates with a seam tape to form a seam having a transmissive optical density within ±

50% of the transmissive optical density of the sign face substrate when the sign face is illuminated from behind the sign face substrate, said method comprising the steps of;

(a) providing at least two sheets of sign face material, such that each sheet comprises a composite of two layers of a thermoplastic material and a scrim layer sandwiched between the two layers of thermoplastic material;

(b) aligning said two sheets such that an edge of each sheet is in an adjoining position and defines an adjoining region without any gaps between the adjoining sheets of sign face material;

(c) positioning a seam tape in said adjoining region such that a portion of said tape simultaneously overlays and contacts each sheet within the adjoining region and extends substantially the length of the adjoining region, said tape comprising a seam scrim substantially embedded in a seam thermoplastic material having an index of refraction similar to the scrim of the seam tape, said seam scrim capable of being substantially wetted out by said seam thermoplastic material;

(d) heating said adjoining region to a temperature which exceeds the melting temperature of said seam thermoplastic material;

(e) exerting sufficient pressure to said heated region to substantially wet out said seam scrim; and

(f) allowing said adjoining region to cool.

2. The method of claim 1 wherein said seam thermoplastic material is selected from the group consisting of polyester, polyamide, polypropylene, polyethylene and polyurethane.

3. The method of claim 1 wherein said scrim is a nonwoven, polyester material.

4. The construction of claim 1 wherein said seam has an optical density within about 50% of the surrounding sign face material.

5. The method of claim 1 wherein said two adjoining sheets of sign face material within the adjoining region overlap one another.

6. The method of claim 1 wherein said seam tape has a second layer of a scrim thermoplastic polymer on the opposite side of said seam scrim than said first layer of scrim thermoplastic.

7. The method of claim 1 wherein said seam thermoplastic material is gelled prior to incorporating said seam scrim into said seam thermoplastic material.