US 3633502 A
For applying characters to tacky sheet material, an apparatus comprising a holding means which releasably holds at least one printing block having at least one intaglio printing face formed by at least one image well, at least a portion of which forms a reservoir for containing a supply of freely flowable powdered ink. A flexible tacky sheet material is adhered over the printing blocks and ink adhered to the tacky surface to provide a desired character arrangement. The printed tacky sheet material can then be adhered to, or the characters transferred to, any desired surface such as signs, posters, etc.
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Description (OCR text may contain errors)
Unite Sttes tent Primary Examiner-J. Reed Fisher Attorney-Kinney, Alexander, Sell, Steldt & Delahunt ABSTRACT: For applying characters to tacky sheet material, an apparatus comprising a holding means which releasably holds at least one printing block having at least one intaglio printing face formed by at least one image well, at least a portion of which forms a reservoir for containing a supply offreely flowable powdered ink. A flexible tacky sheet material is adhered over the printing blocks and ink adhered to the tacky surface to provide a desired character arrangement. The printed tacky sheet material can then be adhered to, or the characters transferred to, any desired surface such as signs, posters, etc.
IN TAGLIO PRINTING BLOCK WITH RESERVOIR FOR POWDERED INK BACKGROUND OF THE INVENTION This invention relates to an apparatus for and method of applying characters to tacky flexible sheet material.
Devices for lettering posters, signs, and visual aids in schools, colleges, labs, churches, stores, shops, etc., exist in numerous forms, but all have disadvantages. For example, lettering stencils and guides provide neat lettering, but are slow and time consuming when preparing several copies for the same message. Steel rule dies useful for cutting characters are expensive, difficult to use, and noisy when used. Letters printed on release liners, which can be applied to surfaces by locating the letter on the surface and rubbing the back of the liner to transfer the letter, are inefficient and wasteful if it is desired to print the same message several times, the supply of repeatedly used letters being rapidly depleted. More recently, strips of relatively thick PVC tape have been embossed to provide white letters against a colored background, but they are relatively expensive, tend to curl, peel off the surface adhered to, and are generally available only in relatively small letter sizes.
Characters have been applied to flexible tacky sheet material in several ways, e.g., by printing roller (US. Pat. No 2,223,907), or by means of a stencil (British Pat. No. 1,120,602, US. Pat. Nos. 2,787,556 and 2,940,864). However, it is necessary to cut a new stencil or provide a new printing roller for each message to be printed, or use large expensive and cumbersome equipment.
Despite the recognized desirability of printing on flexible tacky sheet materials with an apparatus which provides highresolution characters, rapid changing of characters, easy correct spacing of characters and complete word groups, ability to provide numerous reprints without re-inking and which can print in various colors, all without use of messy wet ink rollers or pads and at low cost with little need for expert skill, such an apparatus has never, to the best of my knowledge, heretofore existed.
SUMMARY This invention provides an apparatus for and method of applying characters to tacky flexible sheet material. The apparatus provides high-resolution characters, rapid changing of characters, easy correct spacing of characters and complete word groups, ability to provide numerous reprints without reinking, and printing in various colors, all at relatively low cost with little need for expert skill and without the use of messy wet ink rollers or pads.
In accordance with the invention a holding means releasably holds at least one printing block having at least one intaglio printing face formed by at least one image well, at least a portion of which forms a reservoir for containing a supply of freely flowable powdered ink sufficient for repeated printings without replenishing the ink supply. A flexible tacky sheet material is placed over the printing block in intimate contact with the intaglio printing face and powdered ink from the reservoir thereafter adhered to the tacky substrate to form printed characters having the shape ofthe mouth of the image well. The tacky sheet material with printed characters thereon is then removed from the printing apparatus and adhered to, or the indicia transferred to, any desired surface.
BRIEF DESCRIPTION OF THE DRAWING Understanding of the invention will be facilitated by refer ring to the accompanying drawing, in which like numbers refer to like parts in the several views and in which:
FIG. 1 is a top plan view of a preferred printing apparatus embodying the principles of the invention;
FIG. 2 is a cross-sectional view of the apparatus of FIG. 1, taken along section line 22;
FIG. 3 is a top plan view of a second printing apparatus embodying the principles ofthe invention;
FIG. 4 is an enlarged cross-sectional view of the device of FIG. 3 taken along section line 4-4;
FIG. 5 is an enlarged top plan view ofa printing block useful in the apparatus of FIG. 3;
FIG. 6 is a cross-sectional view of the printing block of FIG. 5 taken along section line 6-6;
FIG. 7 is a bottom plan view of a strip of flexible tacky sheet material having characters applied thereto by means of the printing apparatus of the invention.
The overall construction and use of printing apparatus 10 and 40, in total, are best shown in FIGS. 1 and 3, while structural details are illustrated primarily in FIGS. 2 and 4 through 6.
DESCRIPTION OF PREFERRED EMBODIMENT The embodiments shown and described in drawing are those preferred for applying characters to flexible tacky adhesive tape.
In the drawing, printing apparatus 10 comprises a pair of holding arms 11, a pair of spring clamps 12 and at least one printing block 20. Holding arms 11 are conveniently of steel, aluminum, brass, or a rigid plastic and securely hold blocks 20 in a desired relatively rigid predetermined arrangement. The length of arms 11 is a matter of choice and need be only enough to hold as many blocks 20 as may be necessary to form the desired character arrangement or message, a convenient length being about 12 inches. Blocks 20 preferably extend slightly above the upper surface of arms 11 so a tacky sheet material may be conveniently adhered to the top surface of blocks 20. Inner opposing faces 13 of arms 11 desirably have frictional surface 14 thereon to provide secure contact between arms 11 and blocks 20 to hold blocks 20 in position during the printing of characters. Preferred frictional surfaces 14 are vinyl or urethane foams, although it is possible to achieve good results merely by roughening the inner faces 13 or arms 11 by sandblasting or abrading. Clamps 12 are preferably of spring steel to securely hold arms 11 in cooperar tive relatively rigid parallel arrangement, however, it is readily possible to use numerous other equivalent means of clamping arms 11 together.
Printing block 20 has intaglio printing face 21, formed by at least one engraved image well in upper surface 22 of block 20, the mouth ofthe well defining a character such as a number or letter. Bottom surface 23 of the image well forms a reservoir for containing a supply of freely flowable powdered ink 24, a part of said surface being at least 0.125 inch below the mouth of the image well. This provides printing face 21 with an adequate supply of ink 24 for repeated printings on tacky sheet material 25 without need for replenishing the supply of ink 24 after each printing. Block 20 may be of any shape which permits close adjacent arrangement, but is preferably a rectangular prism having a length between 0.25 inch and 8 inches, a width between 0.125 inch and 6 inches, and a height between 0.2 inch and 2 inches, Block 20 is conveniently die cast or machined of aluminum, zinc, etc., or stamped from steel, aluminum, zinc, copper, etc. It may also be molded from a wide variety of plastics such as acrylics, nylon, phenol-formaldehyde resin, etc. To minimize static charges, it is preferred to use conductive printing blocks, e.g., of metal, metal plated plastic, or plastics incorporating conductive metals or compounds.
The area of upper surface 22 of block 20 forming the mouth of the image well is relatively flat and is at least 0.015 inch wide, preferably 0.05 inch, on each side of the mouth of the image well to provide a land area sufficient to permit adequate adhesion of tacky sheet material 25 thereto. This provides sharp high-resolution characters 26 by causing ink 24 to print in the exact shape of the mouth of the image well in block 20.
Surface 22 forms substantially a right angle with sidewalls 27 of the image well in block 20, the comer 28 formed having a radius of curvature of at least 0.005 inch. This radius provides high-resolution printed characters 26 having sharp edges. A
larger radius of curvature permits ink 24 to adhere to sheet material 25 in a manner which often results in a fuzzy edge on printed characters 26. The land area surrounding the mouth of the image well in block 20 may be raised above upper surface 22 of block 20 to form a relatively narrow raised outline 29. This permits tacky sheet material 25 to adhere to outline 29 and not to upper surface 22 of block 20, providing for ease of removal of tacky sheet material 25 from blocks 20 at low-peel adhesion values without harming its tacky surface, thereby permitting better adhesion to posters and signs. Further, having a small contact area between tacky sheet material 25 and blocks 20 minimizes the generation of static electricity that may be created when sheet material 25 is removed from blocks 20 and which might otherwise inadvertently cause ink 24 to be attracted to and adhere to sheet material 25 in an undesired manner.
The reservoir formed at the bottom of the image well has a capacity large enough to contain sufficient powdered ink 24 to provide repeated printings without refilling. In the embodiment of FIGS. 1 and 2, the mouth of the image well is at least 0.015 inch wide and at least 0.015 inch deep, a part of the well being at least 0.025 inch deep. The portion of the well greater than 0.015 inch deep is at least 0.015 inch wide to permit free flow of ink 24 to and from printing face 21. Further, some portion of the depth of the image well, e.g., the distance from upper surface 22 to bottom surface 23, is greater than the width of the well mouth in printing face 21 up to a. well depth of 0.5 inch. However, the image well need not necessarily exceed a depth of 0.5 inch in the instance ofimage wells exceeding a width of 0.5 inch. These well depths permit the supply of ink 24 to be maintained sufficiently below surface 22 so that it is not easily spilled, prematurely contacted by tacky sheet material 25 to cause undesired printing, or attracted from reservoir 24 by static electricity. This well depth also permits excess ink 24 to fall away from tacky flexible sheet material 25 before it is removed from blocks 20, assuring sharp highresolution characters.
Printed tacky sheet material is formed by providing characters 26 on tacky sheet material 25 by any of several different methods. For example, blocks 20 are arranged to spell a desired message and clamped in place by means of arms 11 and clamps l2. Powdered printing ink 24 is placed in the bottom of the image well after which tacky sheet material 25 is adhered over printing face 21 of blocks 20 so as to completely cover the printing well. Printing apparatus is then inverted, ink 24 coming into contact with and adhering to tacky sheet material 25 to form characters 26 having the shape of the image well. Apparatus 10 is then turned upright, returning excess ink 24 to the bottom of the image well, after which tacky sheet material 25 with printed characters 26 thereon is removed from blocks 20. The printed tacky sheet material can then be adhered to any substrate on which it is desired to place the lettering. Alternately and preferably, powdered ink 24 is magnetic, thereby being attracted and adhered to tacky sheet material 25 by passing a magnet over the upper surface of sheet material 25 when it is adhered in place over printing faces 21. In many instances, it is necessary to remove excess ink 24 from printed sheet material before removing it from blocks 20. Lightly tapping printing apparatus 10 on a hard surface adequately removes excess ink 24 to assure high-resolution characters 26. It is also possible to utilize vibratory, electromagnetic, or electrostatic forces to apply ink 24 to sheet material 25 and to remove excess ink 24.
If desired, apparatus 10 may be used to provide a product having raised characters 30, and useful for subsequent application to surfaces to provide simulated engraved printing. To illustrate, a cellulose acetate tacky sheet material 25 (e.g., SCOTCH" Brand Magic Transparent Tape) is placed over printing blocks in the hereinbefore described manner to form a seal on outline 29, ink 24 is caused to adhere to tacky sheet material 25, and thereafter the upper surface of acetate sheet material is exposed to heat. The acetate sheet material softens and puffs up. After the heat source is removed, the
sheet material retains the raised or puffed configuration to provide raised characters 30, the shape of which correspond to the mouth of the image well in intaglio printing face 21. An infrared heat lamp is a preferred heat source, although a heated iron is adequate.
Tacky sheet material 25 is typically one of several commercially available transparent pressure-sensitive tapes, the use of which provides positive characters on a tacky sheet material which can be adhered to posters, etc. However, it is possible to use negative, e.g., mirror image, intaglio printing faces to provide printed characters on tacky sheet material which can be adhered to and observed from the back side of transparent surfaces such as windows. When printing in this latter manner it is, of course, not necessary to utilize transparent tacky sheet materials. If desired, it is also possible to provide printed characters on low tack elastomeric surfaces such as silicone, etc., thus permitting later transfer of the characters to another more tacky surface. Characters printed with thermoplastic inks can be transferred from elastomeric surfaces to other surfaces by application of heat. The tacky sheet material on which transfer characters are applied, need only have sufficient tack to temporarily hold the printed characters in place.
A satisfactory powdered ink 24 useful for printing with the apparatus of this invention has a preferred particle size between about 5 and about 60 microns. Smaller particle size ink is difficult to use because of its light weight. It is difficult to remove excess ink 24 from tacky sheet material 25 and it is excessively affected by static electrical charges. Powdered ink having a larger particle size results in characters showing the particle grain, although this may be desirable in providing textured characters. It is possible to utilize many powdered printing compounds such as powdered thermoplastic inks, toner powders normally used in electrostatic printing, microcapsules, reflective beads, etc.
A black magnetic powdered ink especially suitable for use in the printing apparatus of this invention was made from 40 parts by weight of epichlorohydrin-bisphenol A solid epoxy resin having a melting point of about 95-l05 C. and an epoxide equivalent weight of about 875-],025 (Epon" 1,004, Shell Chemical Company), 60 parts magnetite, 0.9 part conductive oil furnace carbon black (Vulcan XC-72R, Cabot Corporation), and 0.1 part small particle SiO (Cab-O-Sil M-S, Cabot Corporation). The epoxy resin and magnetite were blended, pulverized, and classified, the fraction passing through a 270-mesh sieve and not through a 400-mesh screen being spheroidized. Spheroidizing was accomplished by feeding the classified powder into an air aspirator in a uniform stream at a rate of about 800 g. per hour, the aspirator sucking the particles into an air stream, dispersing them, and forming an aerosol. The aerosol was directed at into an air stream heated to about 950-l,000 F., the powder allowed to settle, and collected by filtration, The carbon black was added, the composition spheroidized at about 740 F. and the SiO blended in to provide a free-flowing powdered black magnetic ink. Colored characters are provided by utilizing commercially available printing powders well known in the art for producing raised print.
Numerous other embodiments of this invention are possible without departing from the spirit and scope thereof. Fore example, it is possible to securely hold printing blocks 20 in a releasable complementary arrangement to provide desired characters by attaching magnets to the bottom of each printing block 20 and arranging the blocks on a metal surface. Conversely, metal blocks 20 can be releasably held on a magnetic surface.
FIGS. 3-6 show an alternate embodiment which provides a single ink reservoir connected to and in communication with one or more intaglio printing faces. Apparatus 40 comprises elongated channel reservoir 41, printing blocks 42, and cover 43. Reservoir 41 is closed on two sides, the bottom, and both ends, and has parallel flanges 44 on inner surfaces 45 of the two sides to provide a means of holding blocks 42 above and in communication with reservoir 41. Printing blocks 42 have intaglio printing face 46, formed by at least one engraved image well in upper surface 47 of block 42, the mouth of the well defining a character. The image well is open to and communicates with reservoir 41 for containing a supply of ink 24, the bottom of the image well in efiect being the bottom of reservoir 41. The previously discussed image well depths and sizes also apply to this embodiment. Lateral supports 48 hold center islands 49 in place and are far enough below surface 47 to permit free passage of ink particles 26 between said supports 48 and tacky sheet material 27. Preferably, supports 49 are at least about 0.03 inch below surface 46 to permit free passage ofink particles,
Printing blocks 42 have, on two opposite sides thereof, parallel grooves 50 which match and cooperate in a complementary manner with flanges 44 to provide a means ofholding blocks 42 above and in communication with reservoir 41, and to provide means of preventing ink 24 from escaping from reservoir 41 except through printing face 46. Cover 43 has, on two opposite sides thereof, parallel grooves 51 which match and cooperate with flanges 44 and permit cover 43 to securely cover that portion of reservoir 41 not covered by blocks 42.
The described structures are a representative disclosure of printing apparatus to be utilized for printing narrow strip pressure-sensitive adhesive tape. The apparatus is not, however, limited to a narrow tape. Any size sheet of flexible sheet material, sufficiently tacky for ink particles to adhere to, may be printed on its tacky surface by the process and apparatus herein disclosed.
I. An apparatus for applying characters to flexible tacky sheet material, said apparatus comprising in combination:
at least one rectangular prism printing block having an intaglio printing face on one surface formed by an image well, at least a part of said well being at least 0.125 inch deep, and the land area surrounding the mouth of said well being relatively flat for a distance of at least 0.015 inch from the edge of said mouth, whereby said image well forms a reservoir to contain a supply of freely flowable powdered ink; and
a holding means for securely holding said printing blocks in releasable complementary arrangement whereby said blocks provide a desired character arrangement, said means comprising a pair of holding arms secured to each other in spaced substantially parallel relationship by releasable spring clamps, said holding arms having a friction increasing material on the inner opposing surfaces thereofin contact with said printing blocks.
2v An apparatus for applying characters to flexible tacky sheet material, said apparatus comprising in combination:
at least one printing block having at least one intaglio surface, said face being formed by at least one image well at least 0.125 inch deep, the land area surrounding the mouth of said well being relatively flat for a distance of at least 0.015 inch from the edge of said mouth, at least a portion of the depth of said image well being greater than the width of said well mouth in said printing face to a well depth of 0.5 inch, and
a pair of holding arms secured to each other in spaced substantially parallel relationship by releasable clamps for securely holding printing blocks in releasable complementary arrangement, said holding arms having a friction increasing material on the inner opposing surfaces thereof in contact with printing blocks.
thereof, said face being