CA2238720A1 - Labor-saving process and article for making dimensional sign graphics - Google Patents

Abstract

A sign having raised or recessed, three-dimensional graphics (20) and a method of making the sign are disclosed. The sign is fabricated from a laminated, multilayered blank (10) having a substantially continuous face layer formed of a conformable, thermoplastic material (12); a substantially continuous middle layer (14) formed of a colored film; and a substantially continuous profile layer (16) formed of a profile film. In use, dimensional characters (20) are cut into the blank (10) through the profile (16) and middle layers (14) only.
Unwanted material is weeded out from around the cut, dimensional characters (20) and the resulting blank (10) is vacuum-thermoformed to cause the uncut face layer (12) to conform to the dimensional characters (20). A background sheet of a color contrasting to the middle sheet is then laminated to the back of the blank to form the completed sign.

Description

CA 02238720 1998-0~-27 Labor-Saving Process and Article for Making Dii... -ional Sign Graphics Technical Field This invention relates to three dimensional ~if?n~ge~ and particularly to three dimensional signage having textural and decorative relief, as well as amethod of making such ~i~n~ge Back~round of the Invention Current methods to produce three-dimensional (3-D) custom signs include in-11lstri~lly dedicated technologies such as sandblasting, acid-etçhingrouting, in~ection molding, photoemulsion, thermoformin~, and vacuum molding processes. However, these processes each have a variety of limitations incl~1ding large capital inv~ , a required high level of technical expertise, and expensive15 set-up for individual signs. Such processes are also limited in their ability to quickly and inexpensively vary design, color, fonts, etc. Some processes, such as acid-etrhin~, injection molding, and vacuum fu,ming require wet chemical processing, molten material processing or very high processing temperatures. Furthermore, process limitations, such as time-con.c-1ming and costly tooling and critical 20 registration techniques for font and layout design (particularly in injection molding and vacuum forming methods), require mass produced sign quantities to be economically feasible. The result is a severely restricted design choice (color, font, layout, texture, etc.) for the graphic design~r.
Other processes that provide some degree of custom color selection 25 typically can require critical ,egi~ lion techniques, or the application of abradable or chippable color layers to the sign face. Many of these processes preclude integration of formed Braille dots as a visually appealing part of the sign face.
In vacuum thermoforming processes, both male and female molds are used in the industry. These molds are usually reused for multiple copies. The 30 molds do not become part ofthe finished sign. While b~ckfilling ofthe hollow characters with a foam or other liquid resin is possible, most thermoformed signs are backlit and retain hollow characters.

CA 02238720 1998-0~-27 W O 97t23858 PCTrUS96/17750 Some processes use a protective overlay film around applied raised graphic characters with minim~l air el~LI~3ll~ent. While o~lil~g the latitude ofelectronic-cut font generation capabilities, there are limit~tinns in the capabilities of such processing methods to address the visual quality of the cut raised letters, color 5 design selection, hardness, and h~n~ling durability.
At present, there does not exist an entirely s~ f~rtory means for providing three-dimensional signs in limited quantities or employing custom designs having a wide latitude of design as compared to flat signage constructions.
Furthermore, the Federal Government has recently adopted the 10 Americans with Disabilities Act (ADA) that requires arçhitechlral signage in all b~ lin~ and places ~cce~ible by the public to contain letters, numerals, and Braille characters that are raised offthe surface ofthe sign. The Act specifies that thecharacters must be raised at least 0.031 inches (O.B13 mm) above their supporting surface, so as to be easily (li.ctin~ hed, even by touch, by a disabled person. ln 15 addition to complying with the new legislation, the sign should also look aesthetically pleasing and be durable under heavy use conditions.
U.S. Patents Nos. 5,246,757; 5,346,571; and 5,389,413 each describe methods for making signs having raised graphics as well as the signs resulting from such methods. Although such signs are durable and offer excellent visibility and20 aesthetics, the methods used to produce such signs are complex. Accordingly, such methods may not be well-suited for use in small sign shops or sign shops contained within another facility such as a hospital or other public building.

Summary of the Tnvention In view of the above, a need exists for methods for producing signs which are durable, compliant with the Americans with Disabilities Act, and which may be 30 fabricated using a minimllm number of processing steps and materials.

CA 02238720 1998-0~-27 W O 97~3858 PCT~US96/17750 The present invention relates to a method for making signs having raised or rece~.ced graphics, as well as a sign blank for use therewith. More particularly, the present invention relates to a three-layered blank having a face layer formed of a clear or tr~n~luc~nt thermoplastic film, a middle layer formed of a colored film, and 5 a profile layer formed of a relatively thick profile film. Each of the layers is substantially contimlo~ with the layers being bonded together using an adhesive such as a pressure sensitive adhesive (PSA). At least the PSA between the colored film and the clear or tr~n.~ cet ~ thermoplastic film is a tran~ enl PSA to thereby allow the colored film to be visible through the thermoplastic film.
The blank is used to form a sign by a method which in~ s the steps of: a) cutting a reverse of the infçnded sign graphics into the blank in a manner such that the profile film and the colored film are cut, while leaving the clear thermoplastic film scored, yet subsL~llially uncut and intact, b) weeding portions of the profile film and the colored film from the blank in a manner such that all portions except 15 the intenclecl sign graphics are removed, c) thermally forming the sign such that the clear thermoplastic layer is caused to conform around the profile and colored film portions rçm~ining after the weeding step, and d3 applying an appropriate background color to the back of the sign, such as by l~min~ting or p~inting The res--lting sign may be optionally embossed with Braille or other tactile characters, 20 and then affixed to a suitable surface.
In one embodiment, a carrier sheet having a release layer may be affixed to the back of the sign using a PSA. Upon removal of the carrier sheet, the sign may be affixed to any suitable surface or sign base. ~Iternatively, hook-and-loop f~ten.ors, or other f~.~t~nin~ systems may be used to apply the sign to a surface.

~ Brief Description of the Drawin~s FIG. I is a sch~m~fic lepresellLa~ion of a sign blank for use with the method 30 ofthe invention.

CA 02238720 1998-0~-27 FIG. 2 is a s(~.hem~tic reprçsent~ti-)n of a sign blank that has had ~1im~n.~iona characters cut partly therethrough.
FIG. 3 is a sr.h~m~tic replesel~ ion of a sign blank that has been weeded to remove unwanted portions thereof.
FIG. 4 is a schematic re~ on of the sign blank of FIG. 3 that has been vacuum-thermoformed to create a sign face having a raised profile.
FIG. S is a s~h~m~tic repr~lsent~tion of a sign face having a background film l~min~te~ thereto to form a completed sign.
FIG. 6 is a s-.h~m~tic leplesell~aLion of a sign which includes a pressure 10 sensitive adhesive, and a carrier with a release layer.
FIG. 7 is a sçh~m~tic representation of the sign of FIG. 6 with the carrier and release layer removed.

Description of the Preferred Embodiments Conventional Methods:
Conventional methods for forrning signs having raised or recessed, 3-dimensional graphics involve numerous process steps. For example, a process usedby Minnesota Mining and M~mlf~r~tl~ring Company, the applicant herein, involves an eleven-step process which comprises:
1~ T.~.";,.,.l;l.g a profile film to a color film having a release layer on the side opposite that to which the profile film is l~min~ted;

2) Cutting the l~min~te7 using a computer-aided design and m~mlf~ctllring (CAD/CAM) knife cutter to cut ~iimçn~ nal alph~n~lmeric and pictorial charactersin reverse through the top profile film layer and the color layer, while leaving the 2~ release layer of the color film slightly scored;

3) Weeding out (i.e., removing) the l~min~te around the dimensional characters;

4) Applying a prespace tape over the dimensional characters;
S) Removing the release layer from the prçspaced dimensional characters;
6) 1 .~ g the presp~ced dimensional characters to the underside of a clear therrnoplastic top film;

CA 02238720 1998-0~-27 W O 97/23858 PCT~US96/17750 7) Removing the prespace tape;
8) Thermally forming the sign on a vacuum stage to cause the top film to deform and co.~,... to the shape of the l~n~in~ted dimensional characters;
9) T ~mit~ting a colored background film of a color contrasting with the 5 earlier color film to the back of the sign;
10) Optionally embossing Braille characters into the sign; and 11) Mounting the sign on a sign base such as an acrylic or polycarbonate with a Is~ n~ PSA.
~ As should be appa, elll, the method described above can be complex and 10 time con~lmin~, and requires many processing steps in which an error could reduce the quality and value of the completed sign. In contrast, in the inventive method described below, at least four process steps are elimin~te-~, thereby rendering a simpler process having a substantially reduced likelihood for error during fabrication of the sign.
Method:
The method of the present invention is best understood with reference to the 3~igures. Additionally, as will be described in detail below, the inventive method makes use of a novel article which serves as a blank during fabrication of the sign.
The method for fabricating signs in accordance with the present invention is carried 20 out as follows:
1) A blank 10 which comprises a three-layered l~min~te is provided. The blank comprises a clear thermoplastic face layer 12, a colored middle layer 14, and a profile film layer 16. In one embodiment, each of the layers are bonded togetherusing a PSA 18. At least the PSA 18 between the face 12 and middle 14 layers is 25 transparent to allow the color of the middle layer to be vi~ li7~-1 through the face layer. (FIG.1) 2) The blank 10 is cut using a CAD/CAM knife cutter to cut dimensional alphanumeric and/or pictorial characters 20 in reverse, (i.e., rnirror-image), through the profile film layer 16 and the color layer 14, while leaving the clear thermoplastic 30 (face) layer 12 intact and substantially uncut. (FIG. 2) CA 02238720 1998-0~-27 W O 97~3858 PCT~US96/17750 3) The cut l~min~te (i.e., the profile film 16 and color film 14 layers) is weeded out around the dimensional characters 20 to remove waste material 22 and leave only the characters 20 lz~min~ted to the thermoplastic face 12. (FIG. 3) The resulting assembly is referred to herein as a "cut blank" or "sign interme~ te".4) The cut blank is then inverted and the sign is thermally formed on a vacuum stage to cause the face layer 12 to soften and col~roll~l to the shape ofthe e characters 20. (FIG. 4) 5) A color is applied to the back of the sign, preferably by painting or I~";"~l;..g a colored background film 24 of a color contrasting with the earlier color 10 film 14. (FIG. S) 6) Braille characters are optionally embossed into the sign; and 7) The sign is optionally mounted on a carrier sheet 26 having a release layer 28 and a PSA 30. (FIG. 6) For mounting the sign, the carrier sheet 26 and release layer 28 can be 15 removed while leaving the PSA on the sign back (FIG. 7) and the sign can be adhered, via the PSA, to a surface, such as a wall or sign base, to allow it to be viewed. As an alternative, hook-and-loop fasteners, or other such systems, may be used to af~ix the sign to a sign base or other appropriate surface.
The process described above can overcome many of the limitations of 20 systems known in the art. The inventive method and article are believed to be the first which offer, in combination, each of the following improvements and advantages: a) font variety afforded by electronic cutters, b) capability of fine definition, high quality small font sizes (for room signs, etc.), c) excellent visual quality of characters, d) textured background capabilities, e) simple, low cost 25 processing equipment, fi) safer, lower processing temperatures that allow improved gloss control, g) very fast processing times, h~ excellent conformability around 3-D
characters with minim~l air en~l~p,l,ent, i) excellent durability and weatherability, j) integrated Braille capabilities and Braille dots with desirable tactile qualities, and k) capabilities to meet ADA requirements. Additionally, the process and article 30 allow numerous custom layout capabilities including enh~nced contrast between the characters and the background. Such contrast effects include large color selection CA 02238720 1998-0~-27 W O 97/23858 PCT~US96/177~0 and color con~i~tP.n~y, reflectivity, tr~n~ cçncy, met~llic. effects, pattern effects inrl~llling marbling and wood grain, and di~e. enl tactile contrasts of 3-D characters.
In an alternative embodiment, the cut characters can be removed from the sign blank. In that embodiment, the vacuum forming of the face layer affords recessedcharacters on the sign.
In the vacuum co-~, .nil,g step, the cut blank, with unwanted material weeded out, is placed with the profile film layer facing down on a vacuum table.While a vacuum is applied to the l~min~t~., the thermoplastic face layer (facing up) is heated using, for çx~mpl~, a heat gun. Although it is possible to thermally conform 10 a sign face using only about 1-5 inches Hg of vacuum, it is generally pl er~;l ~ ed to use a vacuum of at least about 10 inches Hg. A temperature of about 121~C
(250~F) is found to provide s~ti~f~ctory results. Temperatures above about 177~C(350~F) tend to degrade the integrity and appearance ofthe layers. Of course, this is dependent upon the actual material ~elected The combination of the heat and the 15 vacuum cause the thermoplastic face layer 12 to conform about the characters 20.
Generally, processing time is dependent upon numerous factors, in~ rling the size of the sign, the face temperature, the vacuum pressure, the thermoplastic material, and the thickness of the thermoplastic layer. Although the processing time is not set for a specific sign size due to various factors, processing times are found to be 20 much faster as co...pared to other sign fabrication processes.
In another embodiment, the sign may be preheated in a frame under heating elements until the top therrnoplastic layer softens. The sign is then lowered quickly onto a vacuum table, whereupon a vacuum is imme~i~teTy drawn using a vacuum surge tank to cause the top layer to conform about the profile characters.
Materials:
As noted above, the inventive method is carried out using a novel, three-layered blank having a clear, thermoplastic face layer 12, a middle color layer 14, and a profile film layer 16. Each of the layers is l~min~ted together using a pressure 3n sensitive adhesive 18. Each ofthe layers used in the blank is subst~nti~lly continuous. As used herein, the term "substantially continuous" is intended to CA 02238720 1998-0~-27 W O 97/23858 PCT~US96/1775 mean that the material extends over an a}ea a~,pl u,c " ~ g that of the llltim~te, completed sign, and is free of voids, interuptions, cracks, apertures, or other such discollLi"uities. Thus, for ~ anll)lc, if the completed sign is to have dimensions of ap~lox,nla~ely 12 inches (30.5 cm) by 24 inches (61.0 cm), then each ofthe face,5 rniddle, and profile layers, as used in the blank, will have similar, if not identical, dimensions.
In one pl t;rel I ed embodiment, the clear thermoplastic layer 12 is a thermoplastic ~heetin~ having a thickness in the range of about 0.001-0.025 inches (0.03-0.64 mm), preferably about 0.010-0.020 inches (0.25-0.51 mm). The material10 is rigid or semi-rigid at ambient temperatures in the environment in which the sign will be used, yet becomes conforrnable at elevated temperatures. The conformability of the material allows it to be molded over the 3-dimensional characters of the sign. As used herein, the term conformable is intended to meanthat the thermoplastic may be reshaped at elevated temperatures, such as temperatures of about 200 ~F (~93 ~C) and above. The thermoplastic provides a rigid and Imiti~ed construction of the entire face of the sign. Although a flexible material may be used in some applications, the sign face would not be as durable, nor would it retain Braille or other formed textures as well.
Layer 12 is preferably transparent in order to allow visll~li7~tion of contrasting color layers, however, it could itself also be colored. Gloss control of layer 12 may also be provided by way of fillers, surface texture, coatings or the like.
To achieve the ~ d level of durability, the thermoplastic preferably has a ShoreD hardness greater than about 50, preferably greater than about 65, or a Shore Chardness greater than about 75, preferably greater than about 85. Thermoplasticsthat soften and become col~llllable below about 149~C (300~F) provide visually acceptable signs and offer excellent conformation to 3-D characters using moderate processing temperatures (about 121~C, 250~F). Examples of such materials include, but are not limited to, modified polyesters, polyvinyl chlorides, cellulose acetate butyrates, polystyrenes and the like.
The rniddle7 color layer 14 is preferably a conformable film material having a thickness in the range of about 0.001-0.005 inches (0.03-0.13 mm), having a =

CA 02238720 1998-0~-27 W O 97/23858 PCT~US96/17750 subst~nti~lly transparent PSA layer on its upper surface. The PSA layer is used to l~min~te the color layer 14 to the clear, thermoplastic face layer 12. The color layer must also be cuttable using a CAD/CAM knife cutter. The material should not deteriorate at processing temperatures. Suitable film materials include, but are not S limited to, vinyl chloride-co~ ,;g polymers. In one p,t;re-,~d embodiment, themiddle color layer is formed of a SCOTCHCALTM Series 7725 film m~ntlf~ctured by Minnesota Mining and M~nl~f~ctl~ing Company (St. Paul, Minnesota) he, ei referred to as "3M".
Alternatively, a separate color layer need not be used to provide a contrast between the characters and the background. Rather, the contrasting color can be provided by a colored PSA applied to the surface of the profile characters that contacts the face material, or the color could be that of the profile film itself. In yet another embodiment, the color could be provided by a layer of a colored medium such as a paint, dye, pigment, inlc or the like, applied to either the surface of the profile film which faces the thermoplastic layer, or the surface of the thermoplastic layer which faces the profile film. In this latter case, as in the case of a colored PSA, the color must be removeable from the thermoplastic layer during the profile film weeding step described above.
The profile film layer 16 is preferably a PSA-backed film material having a thickn~s in the range of about 0.010-0.050 inches (0.25-1.27 mm). The material must be able to with.ct~nd sign processing temperatures and conditions without structural degradation. In general, the height of the 3-D characters should not exceed about 1.4 times the width of such characters, although this ratio is not intended to be limiting and will vary depending upon the thermoplastic material used. In the pl t;rc;. lt;d embodiment, the color and appearance of the profile film layer 16 are not important because the middle color layer 14 overlies and hides the profile layer. Additionally, imperfections cut into the profile layer can usually be easily masked by the color 14 and thermoplastic face 12 layers conformed around it.
The profile film layer functions primarily as a "mold" to form characters in the thermoplastic face layer 12. Because the profile film characters remain in the completed sign, the profile film provides reinforcement, durability and strength to CA 02238720 l998-0~-27 W 097/23858 PCT~US96/17750 the sign. As such, the characters cannot readily be pushed in on themselves, collapsed or otherwise deformed. Suitable profile film materials include, but are not limited to filled rubber materials such as 3M SCOTCHCALTM Series 7795 High Profile Film (0.032 inch thickness).
The background color layer 24 can be a colored or patterned eol~ol "-able layer, and preferably is coated with a substantially transparent PSA to allow it to be vi~ ed through the thermoplastic layer 12. Examples inrll1d~ but are not limitedto, 3M SCOTCHCALTM Series 7725 and Series 3630 tr~n~luc~nt films, 3M
DINOC~M patterned films, and 3M SCOTCHPRIN rTM design films. Alternatively, a background color may be provided by a wet applied ink, dye, paint, or paint film.
As noted above, carrier 26 and release 28 layers can be adhered to the back of the sign using an adhesive. Upon removal of layers 26 and 28, the adhesive remains on the back of the sign, allowing the sign to be adhered to a surface. The carrier and release layers are typically provided as an integral unit. For example, the carrier 26 may be a paper or polymeric film having a release layer formed by a silicone coating on one side. A suitable adhesive is provided on the silicone release layer. One example of a suitable carrier/release/adhesive construction is SCOTCHCALTM Series 7790 I~ E adhesive, available from 3M.
Suitable adhesives for use in the present invention typically have a 180~ peel test strength of 1-6 Ib/inch as described in ASTM D 3330-87 (Peel Adhesion of Pressure-Sensitive Tape at 180 Degrees Angle). As noted above, the prefe.~d adhesives are pressure sensitive adhesives (PSAs). Such adhesives develop sufficient bonding power upon application of light pressure. In addition to PSAs, suitable adhesive systems include thermoplastic adhesives, cro.~.~linking adhesive systems, and the like. Optionally, an adhesion enhancer or primer may be applied to one or both bonding surfaces to enhance adhesion.

Example A sign having raised white text was made as follows:

CA 02238720 1998-0~-27 W O 97/23858 PCTnJS96/17750 1) White SCOTCHCALTM 220-10 film (2 mil pl~tici7ed vinyl with a layer of about 1 mil clear acry}ic PSA) was l~min~ted to the smoother side of a thermoplastic face layer which comprised SCOTCHCALTM 7790 film (a clear 0.015 inch impact-modified poly~vinylchloride/vinylacetate) thermoplastic, available from 5 3M).

2~ To the white vinyl film side was l~min~ted SCOTC~HCALTM 7795 Profile Filrn (32 rnil filled rubber with a layer of PSA). This three-part l~min~te con~tit~-teS
the novel blank of the present invention.

3) The blank was placed onto a Zund P1200 flatbed cutter with the 10 thermoplastic face layer against the table surface.

4) The knife pressure of the cutter was adjusted to allow alphanumeric characters to be cut through the profile film and SCOTCHCALTM 220-10 film layers, but not through the face film. (At most, the face film was scored by thecutter).

5) After cutting, unwanted profile film and SCOTCHCALTM 220-10 film were weeded off of the face film sheet using a knife blade and tweezers.

The resulting construction was then processed into a sign using conventional thermoforming and background fflm l~",i~ procedures as described above.

Equivalents Various modifications and alterations to this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention. It should be understood that this invention is not intended to be unduly limited by the illustrative embodiments and examples set forth herein and that such examples and embodiments are presented by way of example only with the scope of the invention intçnclçd to be limited only by the claims set forth herein as follows.
Fo} example, the multi-layered sign blank can have a conformable thermoplastic material that is substantially clear or selected from the group W O 97123858 PCTrUS96/17750 COI~Si~illg of modified polyesters, polyvinyl chlorides, cellulose acetate butyrates, polystyrenes and copolymers thereof, or both. The conformable thermoplastic material can have a thickness in the range of about 0.03-0.64 mm or even a thickness in the range of about 0.25-0.51 mm.
The blank can also have a middle layer that comprises a vinyl chloride CC..~ polymer and can have a thickness in the range of about 0.03-0.13 mm.
The blank can also have a profile film that comprises a filled rubber, and wherein the profile film has a ~hic1~nec.~ in the range of about 0.25-1.27 mm.

Claims

Claims What is claimed is.

1. A multi-layered sign blank which comprises:
a) a substantially continuous face layer formed of a conformable thermoplastic material;
b) a substantially continuous middle layer formed of a colored film; and c) a substantially continuous profile layer formed of a profile film; wherein each of the face, middle and profile layers are contiguously laminated together into a substantially continuous sheet, wherein the profile film is able to withstand sign processing temperatures and conditions without structural degradation.
2. The multi-layered sign blank of Claim 1, wherein at least one of the layers is laminated to at least one of the layers using a pressure sensitive adhesive.
3. The multi-layered sign blank of Claim 1, which further includes cuts to define dimensional characters, the cuts passing through the profile film and thecolored film while leaving the face layer intact.
5. A method of making a sign having a three-dimensional profile which comprises the steps of:
a) providing a sign blank which comprises:
i) a substantially continuous face layer formed of a conformable thermoplastic material;
ii) a substantially continuous middle layer formed of a colored film:
and iii) a substantially continuous profile layer formed of a profile film;
wherein each of the face, middle and profile layers are contiguously laminated together into a substantially continuous sheet;
b) cutting the blank to define dimensional characters, the cuts passing through the profile film and the colored film while leaving the face layer intact;
c) removing unwanted profile and colored film from the thermoplastic material, while leaving the dimensional characters affixed to such material; andd) applying heat and pressure to the thermoplastic material in a manner which causes it to substantially conform to the dimensional characters.

6. The method of Claim 5 which further includes the step of affixing a background sheet to the sign, the background sheet being of a color which contrasts with the color of the film comprising the middle layer.

7. The method of Claim 5 which further includes the step of embossing Braille characters in the sign.

8. The method of Claim 5 which further includes the step of applying an adhesive to the sign in a manner which allows the sign to be affixed to a surface.

9. The method of Claim 8 which further includes the step of affixing a carrier having a release layer to the sign, the release layer positioned between the carrier and the adhesive.