Minimum visibility seam tape and method of joining...

Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C040S603000, C040S604000, C156S098000, C156S304400, C428S061000, C428S063000, C442S046000, C442S058000, C442S131000

Reexamination Certificate

active

06322657

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a seam tape and method of joining at least two substrates with the tape to provide a seam having minimum visibility. The substrates joined are typically sign faces or awnings comprising a composite of plastics and a woven scrim. The seam tape is a woven or nonwoven scrim embedded in a thermoplastic.
2. Description of the Related Art
Signs, awnings, canopies, fascia and banners (hereinafter referred to as signs) are utilized in applications requiring a strong, flexible, weather-resistant material. These signs are used indoors and outdoors and are secured to a frame such that the sign is stretched across the frame. The signs often have various color schemes and graphics emblazoned on them. The colors and graphics can be corporate logos, corporate color patterns, etc. These signs often are rendered visible from a source of backlighting which can either be natural or artificial light. The construction of the sign substrate generally involves a woven scrim sandwiched between layers of polymeric materials such as thermoplastics. The scrims are laminated to a thermoplastic such as polyvinyl chloride, polyester or polyurethane. There are various patents which describe such sign materials, including U.S. Pat. Nos. 3,523,856, 3,968,275, 4,590,027 and 4,242,380. However, one problem which has existed to date is that there is not an adequate material or method to seam these laminates without the seam area being visibly obvious to the viewer. To date, seamed laminates have utilized seam tape with a woven scrim which was very visible in the seamed laminate, thus resulting in a visible seam.
There are numerous reasons for seaming laminates. One commercially-significant reason is to adjoin smaller laminates to create large signs. There is often a need for a sign that is larger than the presently-available sign faces. Therefore, the laminates need to be pieced together to create a larger sign. Another reason to seam is that often the scrim has a visible defect produced during the weaving process. Other defects include oil, dirt, and insects which may become pressed into the laminate during the heating process. These defects are currently removed from the laminate by removing a strip of material that contains the defect. This process reduces the size of the laminate, which leads to the necessity of seaming the laminate to another section of laminate.
The seam must be strong such that the seamed laminate can withstand environmental conditions, i.e., wind, rain, heat, humidity, etc. The seam also must have minimal visibility. A seam which is visible is magnified when the sign is backlit. The seam often shows up as a dark stripe, which is undesirable from an aesthetic point of view. Furthermore, signs often carry logos and colorful graphics in which visible seams can often detract significantly from the visual impact of the intended message.
To date, the above-identified problems involving the seaming of signs have not been adequately addressed. It has now been discovered that the problems of seam strength and seam visibility can be minimized through the use of a unique seam tape which adjoins sign substrates.
SUMMARY OF THE INVENTION
In accordance with the invention, there is provided a sign face construction and a method of making the sign face construction utilizing a minimally-visible seam tape. The sign face construction is as follows:
At least two sheets of sign face material, each sheet comprising a composite of layers with a first and third layer comprising a sign thermoplastic and a second scrim layer positioned between the first and third layer, are positioned such that an edge of each sheet is in an abutting relationship, thereby defining an abutting region. A seam tape extends substantially the length of said abutting region and contacts each of the sheet edges. The seam tape comprises at least a two-layer construction of a woven or nonwoven seam scrim having a relatively open fiber pattern and layer of a thermoplastic material coated thereon. The open fiber pattern of the seam scrim allows each of the fibers to be substantially wetted by the thermoplastic material in which the fibers are embedded when the tape is heated under pressure.
One method of using the scrim tape to make a sign face construction comprises the steps of:
(a) providing at least two sheets of sign face material, the sheets each comprising a composite of layers with a first and third layer of a sign thermoplastic material and a second scrim layer positioned between the first and third layer;
(b) aligning the two sheets such that an edge of each sheet is in an adjoining position and defines an adjoining region;
(c) positioning the seam tape in the adjoining region such that a portion of the tape contacts each sheet, the tape comprising at least a two-layer construction of a nonwoven or woven seam scrim having a first layer of scrim thermoplastic polymer coated therein, the seam scrim capable of being substantially wetted out by the scrim thermoplastic polymer;
(d) heating the adjoining region to a temperature which exceeds the melting temperature of the scrim thermoplastic polymer;
(e) exerting sufficient pressure to the heated region to substantially wet the seam scrim with said polymer; and
(f) allowing the adjoining region to cool, resulting in a minimally visible seam.
The seam tape of the present invention may also be used to secure replacement patches in sign material which have had imperfections removed, as described hereinafter.
DETAILED DESCRIPTION OF THE INVENTION
It has been found that the seam tape of the present invention may be used to join two sections of sign face material to form a strong, integral sign face with a minimally visible seam. The term “minimally visible” is meant to denote a seam which is not optically objectionable to the naked eye at normal viewing distances. More specifically, individual scrim fibers are not visible to the naked eye.
This is accomplished in the present invention by (1) selecting scrim materials and thermoplastic matrix polymers which have similar indices of refraction, and are the same color or are transparent, and (2) arranging the scrim fibers in an open relation so that under heat and pressure the thermoplastic matrix polymer will flow around and intimately wet and encapsulate the fibers displacing substantially all of the air in the tape. Due to the similar refractive indices of the scrim fibers and the matrix polymer and the absence of air, the fibers become substantially invisible in the matrix, resulting in a relatively invisible seam area.
In addition, the seam area can be further rendered unobtrusive by choosing matrix polymers, scrim materials, and light-absorbing dyes, pigments, etc., so that the apparent color is similar to the sheets to be joined, and the apparent optical density of the seam region is within about ±50% of the region surrounding the seam, preferably within ±25% of the apparent optical density of the region surrounding the seam.
The thermoplastic and scrim materials should also be chosen to be chemically compatible with each other and with the sign materials to be joined. The matrix polymers should adhere well to the sign face materials and should be relatively stable in the environment in which it will be used. Many such materials are available and known to those skilled in the art as described hereinafter.
The seam tape of the present invention may also be used as a patch material. There are often imperfections in the sign face material which can simply be punched out by a die to create an aperture. A replacement patch of the same sign face material is then cut out and positioned in the punched-out aperture. A seam tape patch of the present invention is then cut to a dimension that is bigger than the replacement patch, and placed over the replacement patch. Heat and pressure are applied to the seam tape region, thereby resulting in a patched region having minimum visibility.
The substrates which are secured together by the minimally-visible seam

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Minimum visibility seam tape and method of joining... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Minimum visibility seam tape and method of joining..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Minimum visibility seam tape and method of joining... will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2607321

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.