MANUFACTURE OF TRANSFER DECALCOMANIAS USING ULTRAVIOLET CURE INK AND ADHESIVE TECHNOLOGY BACKGROUND OF THE INVENTION Dry transfer products (typically referred to as decalcomanias) are well known in the art. Such products are composed of a carrier film screen printed with graph- ic designs i. e., lettering, craft art, logos, tole paint- ing, signage, symbols, etc., and subsequently adhesived and protected with a silicone coated release paper. The decalcomania is transferred to the intended receiving surface by removing the protective silicone coated re- lease paper and positioning the decalcomania with the adhesive side against the receiving surface and contact- ing the adhesive by burnishing the carrier film on the opposite side and slowly peeling away the carrier film leaving only the screen ink formed decalcomania attached to the receiving surface.

Decalcomanias are presently manufactured using solvent based screen inks and adhesives.

An example of the above described prior art process is exemplified by U. S. Patent 3,847,725 wherein use of a carrier film, solvent base ink and adhesives are taught.

This patent describes a single color decalcomania whereas it also applies to spot and halftone screen printing.

U. S. Patent 3,847,725 describes a carrier film coated with a non-extensible highly cross-linked polymer- ic coating that is insoluble to organic solvents; a solv- ent/resin evaporative ink and a solvent/elastomeric low tack solvent evaporative pressure sensitive adhesive.

In summary all previously described art teaches a carrier film with a no-stick surface coating, a solvent evaporative ink that will release from the no-stick sur- face and a solvent evaporative pressure sensitive adhe- sive that will aid transfer and bond the indica to the receiving surface.

Such processes necessarily require special efforts and compliance to OSHA and DEP regulations when handling solvent base inks and adhesives. For example, OSHA re- quires proper labeling and handling for employee health and accident safety and DEP requires special permitting and annual reporting of the solvent emissions, called volatile organic compounds or (VOC's). If emissions exceed"low quantity generator status"an expensive sol- vent oxidizer installation will be required to process the VOC's before discharging them to the atmosphere.

The present invention eliminates the following disadvantages of using solvent evaporative inks:

1. Atmosphere pollution from solvent VOC's.

2. Time consuming and complicated solvent emis- sion reporting to the DEP.

3. Implementing and auditing OSHA required safety procedures for solvent inks and adhesives.

4. Solvent evaporative ink tend to dry in the screens and require washing out every 100-500 sheets resulting in costly loss in production efficiency.

5. Cost of expensive drying ovens needed to evap- orate the solvents out of the printed screen ink.

6. Drying ovens require valuable manufacturing floor space.

7. Inability to efficiently halftone screen print above 75 lines per inch resolution.

8. Cost of expensive oxidizer to treat the VOC emissions prior to discharge into the atmosphere.

BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention eliminates the need for sol- vent base screen inks and adhesives in the manufacture of decalcomanias. Rather, this invention employs ultravio- let (U. V.) cure inks and adhesives in the manufacture of decalcomanias. U. V. curable inks produce decalcomanias with tougher ink films resulting in improved scuff and abrasion resistance. U. V. cure systems also increase

process speed and improve ability to print finer halftone screens (100-150 lines per inch resolution) because U. V. ink and adhesive will not dry in the screen.

U. V. screen inks and adhesives will also allow the production of decalcomania in a less hazardous solvent free work place while protecting the environment by elim- inating VOC's.

The decalcomania dry transfer product of the pres- ent invention comprises (see Fig. 1): (1) a carrier film; (2) a non-stick coating applied to the carrier film; (3) a U. V. curable ink for producing the desired indicia which is ap- plied to the non-stick coating; (4) a U. V. curable pressure-sensitive adhesive applied over the indicia formed in feature (3); and (5) a protective release paper or plas- tic coating.

The key inventive features of the present invention reside primarily in features (3) and (4), and the elimi- nation of the prior art solvent steps.

The present process is particularly suitable to produce a single color, spot color, halftone color or a combination of the above screen printing decalcomania, while eliminating the disadvantages of using solvent eva- porating ink previously described.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a cross-section of a dry transfer sheet embodying the present invention and the foregoing ele- ments (1)- (5) described above.

DETAILED DESCRIPTION The present invention may be readily understood by referring to Figure 1 and amplifying each of the compo- nent elements of the present dry transfer sheet.

As depicted in Figure 1: (1) is the base carrier film similar to those con- ventionally used, such as described in U. S. Patent 3,847,725 which description is incorporated by reference.

The carrier film can be polyester, polyethylene, polysty- rene, polypropylene, a vinyl polymer or the like. The

carrier paper can be densified Kraft paper, parchment, transparent paper, etc.

(2) denotes a polymeric coating applied to the car- rier film.

The polymeric coating may be a polymer as described in col. 2 of U. S. Patent 3,847,725 which is incorporated by reference. Thermosetting polymers and especially ther- mosetting acrylics are particularly useful. Such poly- mers must be substantially non-extensible. A modified silicone polymer coating may also be used next to the polymeric coating.

In either case to be useful, the ink release values from the polymeric coating should be between 2-5 grams per inch when measured as described by the pressure sen- sitive tape council's test method number PSTC#-1 and al- low the U. V. cure screen ink to be printed to high print- ing standards and quality.

(3) denotes the decalcomania formed by use of U. V. inks according to the present invention. Such inks are formulated from a blend of monomers, oligomers, photoini- tiators, pigments, additives, modifiers and synergist.

When exposed to U. V. energy, in the 200-400 nanometer range for a fraction of a second, the photoinitiator will absorb U. V. energy, and start the polymerization of the oligomer and monomer until it is completely cross linked changing the U. V. ink from a liquid to a 100% cured sol- id.

The proper selection of monomers and oligomers, etc. will give the cured U. v. ink the desired physical properties such as hardness, flexibility, clarity, color, and releaseability from the carrier film.

1. Oligomers are the resin backbone part of the formula. Ebecryl #1755 is an acrylic oligomer blended with TRPGDA-DEO monomer featuring flexibility. Ebecryl #6700 is an acrylated aromatic urethane oligomer featur- ing toughness and abrasion resistance. They are both manufactured by UCB Chemicals Corp., Smyra, Georgia.

2. Monomers crosslink with the oligomer resins to form a solid. They also act as diluents and contrib- ute to the physical properties of the solid ink film.

Ebecryl TRPGDA is a tripropylene glycol diacrylate.

It contributes flexibility, water resistance, low viscos-

ity, good cure speed, and good solvency for acrylated oligomers without imparting brittleness.

Ebecryl TRPGDA-DEO is a purified grade of tripropy- lene glycol diacrylate. It has the same physical proper- ties as TRPGDA but exhibits low odor.

3. Photoinitiator can be called a catalyst. It starts the polymerization between the oligomer and the monomer. When radiated with U. V. light the photoinitiat- or will absorb U. V. energy and generate free radicals which cause the oligomer and monomer to crosslink into a solid polymerized ink film. Irgacure 907 and Irgacure 1700 are manufactured by Ciba Specialties Chemical Co., Tarrytown, NY.

4. Pigment is used to impart color to the U. V. crosslinked polymer ink film. Pennco #981 black and Pen- nco #9R52 red are pigment paste manufactured by Penn Col- or, Inc., Doylestown, PA.

5. Various Additives FL 430 is a surfactant manu- factured by 3M Corp., St. Paul, MN. It reduces the sur- face tension of the ink and facilitates wetting of the pigments and receiving surfaces. L405 is a defoamer man-

ufactured by Drew Chemical Company (Division of Ashland Chemical Co.), Boonton, NJ. L405 is added to the ink to control fisheyes, cratering, etc. Cabosil #M-5 is a fumed silica added to flatten the gloss and improve vis- cosity. It is manufactured by the Cabot Corporation, Tuslola, IL. Ebecryl P115 is an amine synergist. It is an additive used to increase the cure speed of the U. V. ink and imparts low odor.

Component (4) of Figure 1 are U. V. pressure sensi- tive adhesives. Such adhesives can be purchased from various manufacturers. Two manufacturers are: RAD-CURE Corp., Fairfield, NJ (their product is #UV12PS-8K) and Acheson Colloids, Port Huron, MI (their product #ML2525- 1).

(5) A protective release paper denoted as (5) is used to protect the adhesive and to prevent the indicia from pre-release or pre-transfer to an unwanted surface.

This is a conventional feature. A paper such as vegeta- ble parchment, tissue, or densified Kraft paper, is sili- cone coated to provide the protection.

The components making up the U. V. inks are exempli- fied as follows:

1. Olicfomers and Additives-supplied by UCB Chemicals Corp., Smyrna, GA 30080 EB 220, EB 745, EB 1701, EB 1710, EB 1755, EB 4827 and EB 1755.

2. Monomers-supplied by UCB Chemical Corp. EB CL1039, HDODA, TRPGDA, TRPGDA-DEO PETA. K.

3. Photoinitiators-supplied by UCB Chemical Corp. EB P37, Irgacure 1700*, Irgacure 907*, Benzophenone, EB P115, DVROCUR 1173*, supplied by Ciba Corp.

4. Synergist-supplied by UCB Chemi- cal Corp., EB P115, EB P104.

5. Pigments- Pennco 981 Black Pigment paste* Pennco 9R52 Red pigment paste* Pennco 9579 blue pigment paste* Pennco 9W7 white pigment paste * * supplied by Penn Color Inc.

6. Additives-

FC-430 fluorocarbon surfactant, supplied by 3M Co.

Carnavba Wax, Slip Agent, supplied by F. B. Ross Co., Inc.

L-405 Defoamer, supplied by Drew Chemical Co.

Cabosil M-5 Fumed Silica, supplied by Cabot Corp.

DC-193 Silicone Wetting Agent, sup- plied by Dow Corning.

A typical formula for a black U. V. cure ink is as follows: 100 Parts by Weiqht Oligomer EB 175547.0 Monomer TRPGPA-DE019.0 Pigment PENNCO 98121.0 Photoinitiator IRGACURE 1700 6.0 Surfactant FC430 0.5 Defoamer L405 0.5 Silica Cabosil/M-5 1.0 Synergist P115 5.0 A typical red U. V. Cure Ink is as follows: Oligomer 6700 30.0 Monomer TRPG-DA 26.0

Pigment 9R52 31.0 Photoinitiator IRGACURE 907 6.0 Surfactant, defoamer, silica and synergist are the same as to nature and quantity as the above U. V. cure ink composition.

Additives and modifiers can be added to the inks and adhesives to provide flow, slip, hold out, viscosity, flexibility adjustments as deemed necessary.

U. V. cure ink and adhesive printing conditions are the same as used for standard solvent base ink and adhe- sive printing which is in itself generally well known.

An illustrative description of the present process is as follows: Printing Screen: Mesh for ink, 300-400 threads per ink in either stainless steel or polyester material stre- tched to a minimum tension of 20-24 newtons.

A direct photo emulsion stencil depicting the gra- phics to be printed is firmly adhered and anchored to the mesh.

Press: Any standard flatbed or cylinder or web press capable of controlling registration, and squeegee speed and pressure.

U. V. Cure Process: A standard U. V. cure unit equi- pped with one or two 300 watt per inch mercury vapor lamps fitted with a standard elliptical reflector. Cure speed is normally in the range of 50 to 75 feet per min- ute with exposure to 200-400 monometers for a fraction of a second. For either U. V. cure ink and/or U. V. cure ad- hesive.

Various modifications may suggest themselves to those skilled in the art.

Having described the present invention, that which is sought to be protected is set forth in the following claims.