MXPA98009006A - Water-based ink composition for printing by almohadi - Google Patents

Abstract

An aqueous transfer pad printing composition is provided which comprises effective amounts of a water soluble polymer, an opacifier, and a dispersant and optionally a dye and / or release agents. The composition is particularly suitable for use with silicone rubber transfer pads for printing alphanumeric patterns on curved or spherical surfaces such as ophthalmic lenses.

Description

COMPOSITION OF WATER-BASED INK FOR PRINTING BY DESCRIPTION OF THE INVENTION The present invention relates generally to a printing ink composition for transfer pad that preferably comprises a waterborne vinyl resin, an opacifier, a release agent, a dispersant and a dye. The ink composition is particularly suitable for use with silicone rubber transfer pads for printing alphanumeric patterns on curved or spherical articles such as ophthalmic lenses. The ink formulation is compatible with the surface of the pad such that the pad I accurately transfers the design to a surface that is receptive to the ink which is removable with water. Pad printing or transfer padding is a well-established method for transferring ink in the form of a thin design to a shaped surface such as one having a rounded or similarly irregular contour. This technique differs from traditional printing in that it does not depend on the character to transfer the design. Pad printing has been used corriereially for many applications such as (1) design patterns in light bulbs, watch spheres and golf balls, (2) printing circuits in dielectric substrates, (3) bar code printing and 4) marking of glass or plastic ophthalmic lenses for subsequent identification in prescription filling optical laboratories. There are a number of commercial transfer pad printing systems available. For example, the systems are obtained from Trans Tech America, Inc., Schaumberg, IL. Markem Corporation, Keen, NH; Tampo Print GmbH, Munich and Stuttgart, Germany. The transfer pad printing devices are described, for example, 4,060,031, 4,282,807, 4,615,266, 4,779,531, 4,803,922 and 4,856,670. Although these systems are automated and assembled to accurately transfer the pattern from a printing block (cliché), which contains the ink design to be transferred, a critical step in the process involves taking exactly the ink design from the cliché, without alter the design as it rests on the pad before transferring to a receiving surface. The reproduction of the design in a cliche on a substrate depends on the capacity of the ink composition deposited on the cliche to effectively wet the surface of the transfer pad. If the ink composition does not properly wet the surface of the pad, the pad will not completely take up the ink in the pattern provided in the cliché. Alternatively, the pad can take the ink design by suction of a sufficient mass only to have the design separated (or agglomerated) on the surface of the pad due to an incompatibility between the ink and the surface of the pad before the transfer of the pad. Design to the desired surface. To handle this problem, WO 92/20005 discloses a modified transfer pad printing composition comprising either latex or a solution coating composition which includes a monomeric or polymeric hydroxylated and / or carboxylated surfactant humectant. After transferring the ink composition, printing is completed when the ink dries to form the design. In this regard, inks based on commercially available organic solvents at elevated temperatures should be dried and hardened. The volatile organic compounds in inks based on organic solvents cause environmental problems not only due to their presence but also because acetone or another organic solvent is required to eliminate the printing, which further aggravates the problem. Similarly, it has been observed that some inks based on organic solvents cause a phenomenon referred to as "spooky", where the ink composition leaves an impression on the surface of a plastic substrate after the ink has been erased, (e.g. design) .

The present invention is based in part on the discovery of an aqueous ink composition for transfer pad comprising a marking ink in a waterborne vinyl resin dispersion that is compatible with pad surfaces including those made of silicone rubber. The ink composition, in the conformation of an alphanumeric or any geometric pattern, can be printed accurately on the surface of the pad; after this, the design can be transferred precisely to another surface that is receptive to the ink. In one aspect, the invention is directed to an aqueous coating composition suitable for use in transfer pad printing comprising a water soluble polymer; opaque and a dispersant. Preferably, the soluble polymer is a vinyl resin and the ink composition includes a colorant to improve the appearance of the finished pattern. When the transfer pad is made of silicone rubber, the composition includes a release agent. In another aspect, the invention is directed to a transfer pad printing method for printing a pattern of a liquid coating from a cliche onto a surface of the substrate wherein the liquid coating comprises the aqueous ink composition described above. In yet another aspect, the invention is directed to articles including, for example, ophthalmic lenses, manufactured by this process. In a preferred embodiment, the inventive aqueous ink composition does not include an organic solvent which avoids the hazards associated with inks based on organic solvents. In addition, the inventive ink composition solves the deficiencies of conventional aqueous ink compositions which have not been satisfactory. Specifically, the aqueous inks of the prior art tend to agglomerate on the surface of the silicone rubber pad whereby the design is sufficiently separated such that the resulting printed product is a poor replica of the original design. Additionally, conventional aqueous marking ink solutions generally form very thin and poorly defined prints that lack body and substance. For these reasons, they fail to meet the precision manufacturing environment requirements where readability, clarity, abrasion resistance, firmness and moisture resistance are necessary. One characteristic of inventive water dispersible ink is that it can be dried at room temperature (approximately 22 ° -25 ° C) in just a few seconds, or less time when assisted with air, to form well-defined, good quality prints. which are comparable to those formed from inks based on organic solvents. The impressions are also resistant to abrasion in such a way that articles (for example ophthalmic lenses) that are printed can be packaged and transported safely. Another feature of the invention is that printed ink marks can be easily removed by cold water cleaning. A further feature is that the aqueous ink composition can print patterns on non-coated ophthalmic lenses, which are coated for abrasion resistance and / or anti-reflective. Ophthalmic lenses are often coated with, for example, films derived from polysiloxane, acrylate, epoxy, or urethane-based compounds for abrasion resistance and with multi-layered films comprising silica, titanium oxide and / or niobium oxide for antireflectivity. The invention is directed to water-based ink compositions for marking uneven surfaces. The ink compositions can be used to print any article which can be printed by printing with transfer pad. In the case of ophthalmic lenses, brands are used in the production of lens products. Specifically, the marks identify points of reference in a lens, for example fixation junction, point of the prism, close measurement etc., which guides the laboratory personnel in the grinding, polishing, and other thing that fixes the prescription to that required for the final spectacle product. Ophthalmic lenses are made of materials that have superior structural and optical properties. Preferred substrate materials are crystalline quartz, fused silica, calcium and sodium carbonate silicate glass, and plastics such as polymers based on allyl diglycol carbonate monomers (available as CR-39 ™ and PPG Industries, Inc., Hartford , CT), diacrylate or dimethacrylate compounds as described in U.S. Patents 5,373,033 and 4,912,185 both incorporated herein, and which are available as SPECTRALITE ™ from Sola Optical USA, Inc. Petaluma, CA, and polycarbonates such as LEXAN ™, available from General Electric Co., (including sunglasses). Preferred ophthalmic lenses also include laminated lenses that are fabricated by joining two lens discs (i.e., a front disc and a posterior disc) together with a transparent adhesive. Licked lens discs are described, for example, in U.S. Patents 5,149,181, 5,857,553 and 4,645,317 and U.S. Patent Application, GB 2,260,937 a, all of which are incorporated herein. Suitable substrates further include ophthalmic glass lenses, as described, for example, in U.S. Patent Nos. 3,899,315 and 3,899,314, both of which are incorporated herein. As used herein, the term "lens" refers to both types of individual integral body and laminate. The lenses may not be coated or coated for resistance to abrasion or antireflectivity. Ophthalmic lenses, particularly plastic lenses, are also suitable, which are coated with a polymeric coating with resistance to abrasion or scratches that may be approximately 1 μm to approximately 12 μm in thickness. The thickness of the scratch resistance polymeric coating will depend, in part, on the substrate material. Generally, plastic materials such as polycarbonates will require thickened coatings. Suitable lenses may also have an anti-reflection coating which refers to a substantially transparent multi-layered film which is applied to optical systems (for example surfaces thereof) to substantially eliminate reflection in a relatively broad portion of the visible spectrum, and therefore same increase the transmission of light and reduce the surface reflection. Known antireflection coatings include multi-layered films comprising high and low alternating refractive index materials (for example metal oxides) as described, for example, in U.S. Patents 3,432,225, 3,565,509, 4022,947 and 5,332,618, all of which are incorporate in the present. The thickness of the AR coating will depend on the thickness of each individual layer in the multi-layered film and the total number of layers in the multi-layered film. The AR coating can include any number of layers. Preferably, the AR coating for the ophthalmic lenses has about 3 to about 12 layers, more preferably about 4 to about 7 layers, and more preferably about 4 layers. Preferably, the AR coating is approximately 100 to 750 nm thick. For use with ophthalmic lenses, the AR coating is preferably about 220 to about 500 nm thick. A suitable antireflective coating is described in U.S. Patent Application no. series 08 / 487,365 by Machol, entitled "Anti-reflection Coating", common assignee, filed on June 7, 1995, which is incorporated herein. However, before describing the invention in further details, the following terms will be defined. The term "soluble polymer" refers to suitable water-soluble polymers that are compatible with the other components of the ink composition to form an aqueous polymer mixture that produces a polymer composition with other components impregnated therein when the polymer is dried. mixture. Soluble polymers include, for example, suitable urethanes, acrylates, epoxides, cellulose, and vinyl derivatives. Specific examples include polyurethanes available as NEOREZ ™ from Zeneca Resins, Wilmington, MA, styrene acrylates, available as JONCRYL ™ from Johnson Wax Co. , Racine, Wl, hydroxypropylcellulose available as KLUCEL ™, cellulosic polymers available as AMBERGUM ™ both from Aqualon Co., Wilmington, DE, and aqueous vinyl polymer blends that are available under the AW850, AW100, AW8790, AW875 and WBV100 designations from Union Carbide, Danbury, CT. Preferred soluble polymers are thermoplastics. Preferred soluble polymers for the ink composition comprise vinyl resins which are vinyl polymers or copolymers which are soluble in water at room temperature. The presence of an aqueous colloidal dispersion of the vinyl resins in the ink composition is critical to achieve the desired fluidity, printing and durability of the marking ink. The ink also has good redispersibility characteristics and is easy to remove. Preferably, the vinyl resin is a copolymer of vinyl chloride. Suitable vinyl chloride copolymers are available as a waterborne vinyl dispersant such as, for example, UCA ™ waterborne vinyls (available from Union Carbide, Danbury, CT). A dispersion of vinyl resin transported in preferred water is AW-850 ™, which contains approximately 40% solids, is available from Union Carbide. The soluble polymer typically comprises from about 10% to about 30%, preferably about 15% to 25% and more preferably about 20% to 25% of the ink composition when formulated first, that is, prior to drying. (All percentages in the present are on a weight basis). Another dispersion of vinyl resin transported in preferred water is WBV 100 which contains approximately 50% solids. This soluble polymer comprises from about 10% to 30%, preferably about 15% to 25% and more preferably 20% to 25% of the ink formulation. The term "opaque" or "opaque agent" refers to any suitable substance that imparts strength, durability and / or sharpness to the design or pattern created on a substrate surface when the ink composition has dried. Furthermore, it appears that the opaque agent also improves the consistency and texture of the ink so that it can be easily transferred from the cliche to the surface of articles by the transfer pad. Preferred opacifiers are inorganic materials such as, for example, titanium dioxide, aluminum oxides, aluminum silicates and silica. Titanium dioxide is preferred since it is less abrasive and creates well-defined, superior appearance and designs. When a colorant is used in the ink composition, the opaque Ti02 creates a background which improves the color of the colorant. The opacifying agent typically comprises from about 5% to 45%, preferably from about 5% to 30%, and more preferably from about 10% to 20% of the aqueous ink composition. The term "dispersant" refers to any suitable substance which acts as a wetting agent to disperse the ink components especially the opaque (and dye which is optional) to form an aqueous mixture wherein the unsolved solid fine particles are distributed and evenly separated. Preferred dispersants include, for example, water-reducible alkyls, acrylics, polyesters, epoxides and mixtures thereof. DISPERSE-AYD W-22 ™ (available from Daniel Products, Jersey City, N.J.) is a preferred dispersant. The dispersant typically comprises from about 0.5% to 5.5%, preferably from about 1% to 5%, and more preferably from about 1% to 2.5% of the aqueous ink composition. The term "release agent" refers to any suitable substance that acts as a lubricant to bring the aqueous ink composition to be transferred more easily from the cliché to the silicone rubber transfer pad and from the pad to the surface of the substrate (for example lenses). The silicone rubber material is described, for example, in WO 92/20005. Suitable release agents include, for example, silicone fluids. A preferred release agent is a silicone fluid available as SF1188 ™ from General Electric Co., Waterford, N.Y. The release agent typically comprises from about 10% to 30%, preferably from about 12.5% to 27.5% and more preferably about 15% to 20% of the aqueous ink composition. The term "colorant" refers to suitable substances which impart color to another material or mixture. Dyes are used as desired to make the brand unique, for example, "color code". In addition, the colorants provide improved readability with more cost-effective surface tapes in the lens surface forming process. The dyes typically comprise either non-soluble inorganic dyes and soluble organic dyes. Preferred dyes include Erioglaucine (turquoise blue) and tartrazine (yellow) both available from Aldrich Chemical Co., Milwaukee, Wl. When present, the colorant comprises from about 0.25% to 7.5%, preferably from about 0.5% to 5%, and more preferably from about 0.5% to 2.5% of the ink composition. METHODOLOGY The inventive ink composition can be employed in conventional transfer pad devices which typically comprise a silicone rubber pad to transfer an ink pattern from a cliché ink source and print the design on the surface of an article. (for example, lens surface). The excess ink is removed from the cliché with a medical pallet. Typically, the aqueous ink composition comprises about 20% to 50% water, preferably about 25% to 45% and more preferably about 35% to 45%. The composition is thixotropic and has a viscosity of about 1,000 cp to 20,000 cp, preferably about 5,000 cp to 15,000 cp, and more preferably about 7,500 cp to about 12,500 cp at room temperature. Marks are formed in plastic ophthalmic lenses that identify reference points on each lens using the Tampo Print Hermetic transfer pad printing device models 61 and 90. The devices are available from Trans Tech America, Inc., Schaumberg, IL and are adapted to manufacture ophthalmic lenses. The following examples 1-6 describe representative preferred formulations of the inventive aqueous ink composition. Example 1: 10.81 g of deionized water is added under stirring to 54.3 g of AW850 (soluble polymer). To this is added 1.63 g of DISPERS-AYD W22 (dispersant). 0.81 g of Erioglaucine and 0.11 g of tatrazine (dyes) are then added and the mixture is stirred for 15 minutes. After adding 14.12 g of titanium dioxide, stirring is continued for an additional 2 hours. Finally, 18.19 g of SF1188 (release agent) and stir for 2 more hours. This formulation achieves a teal ink. Example 2: The same mixing procedure as in Example 1 is followed except that AW850 is replaced with 54.3 g of WBV110. Example 3: Add to 60.88 g of AW875 1.79 g of DISPERS-AYD W22 under agitation. 0.9 g of erioglaucine and 0.11 g of tartrazine are then added and the mixture is stirred for 15 minutes. Then 15.92 g of titanium dioxide is added and stirring is continued for an additional 2 hours. Finally, add 20.52 g of SF1188 and stir for 2 more hours. The formulation achieves a teal ink. Example 4: To 64.31 g of AW875 1.29 g of DISPERS-AYD W22 are added under agitation. 0.96 g of tartrazine are then added and the mixture is stirred for 15 minutes. Then 15.43 g of titanium dioxide is added and stirring is continued for an additional 2 hours. Finally, 18.0 g of SF1188 are added and stirred for a further 2 hours. The formulation achieves a teal ink. Example 5: The same procedure is followed as in Example 4 except that AW850 is replaced with 64.31 g of WBV110. Example 6: The same procedure is followed as in Example 4 except that AW850 is replaced with 64.31 g of AW875. After the lenses are printed with transfer pad with the aqueous ink composition, marks are formed on the surfaces of the lenses when the ink composition is dried. At room temperature, drying occurs within a few seconds or less when the aqueous ink composition is blown with air. The marks are easily removable with water. While the invention has been described in terms of several preferred embodiments, the skilled artisan will appreciate the various modifications, substitutions, and changes which can be made without departing from the spirit of the present. The descriptions of the subject matter in this description are illustrative of the invention and are not intended to be construed as limitations of the scope of the invention.

Claims (37)

1. CLAIMS 1. An aqueous coating composition suitable for use in printing with transfer pad characterized in that it comprises effective amounts of (a) water-soluble polymer; (b) an opaque; and (s) a dispersant.
2. 2. The composition according to claim 1, characterized in that the water-soluble polymer is selected from the group consisting of urethanes, acrylates, epoxides, cellulose derivatives, vinyl polymers and mixtures thereof.
3. 3. The composition according to any of claims 1-2, characterized in that the opacifier is selected from the group consisting of titanium dioxide, aluminum oxides, aluminum silicates, silica and mixtures thereof.
4. 4. The composition according to any of claims 1-3, characterized in that the dispersant is selected from the group consisting of water-reducible alkyls, acrylics, polyesters, epoxides, and mixtures thereof.
5. The composition according to any of claims 1-4 characterized in that the water soluble polymer comprises about 10% to about 30% of the composition.
6. 6. The composition according to any of claims 1-5 characterized in that opacifying comprises about 5% to about 45% of the composition.
7. The composition according to any of claims 1-6 characterized in that the dispersant comprises about 0.5% to about 5.5% of the composition.
8. 8. The composition according to any of claims 1-7 characterized in that it additionally comprises a colorant.
9. 9. The composition according to any of claims 1-8 characterized in that it additionally comprises a release agent.
10. 10. The composition according to any of claims 1-9 characterized in that the composition essentially does not contain organic solvents.
11. 11. A process for printing by transfer pad a pattern of a liquid coating from a cliché ink source on a surface of an article characterized in that the liquid coating comprises an aqueous coating composition comprising effective amounts of (a) soluble polymer in Water; (b) an opaque; and (c) a dispersant.
12. 12. The process according to claim 11, characterized in that the water-soluble polymer is selected from the group consisting of urethanes, acrylates, epoxides, cellulose derivatives, vinyl polymers and mixtures thereof.
13. 13. The process according to any of claims 11-12, characterized in that the opacifier is selected from the group consisting of titanium dioxide, aluminum oxides, aluminum silicates, silica and mixtures thereof.
14. 14. The process according to any of claims 11-13, characterized in that the dispersant is selected from the group consisting of water-reducible alkyls, hydrocyls, polyesters, epoxides, and mixtures thereof.
15. 15. The process according to any of claims 11-14 characterized in that the water soluble polymer comprises about 10% to about 30% of the composition.
16. 16. The process according to any of claims 11-15 characterized in that opaque comprises about 5% to about 45% of the composition.
17. 17. The process according to any of claims 11-16 characterized in that the dispersant comprises about 0.5% to about 5.5% of the composition.
18. 18. The process according to any of claims 11-17 characterized in that it additionally comprises a colorant.
19. 19. The process according to any of claims 11-18 characterized in that it employs a silicone transfer pad and wherein the composition additionally comprises a release agent.
20. 20. The process according to any of claims 11-19 characterized in that the composition essentially does not contain organic solvents.
21. 21. An article of manufacture containing a printed design with transfer pad in it, characterized in that the design is formed by the process according to any of claims 11-20.
22. 22. The article according to claim 21, characterized in that the water-soluble polymer is selected from the group consisting of urethanes, acrylates, epoxides, cellulose derivatives, vinyl polymers and mixtures thereof.
23. 23. The article according to any of claims 21-22, characterized in that the opacifier is selected from the group consisting of titanium dioxide, aluminum oxides, aluminum silicates, silica and mixtures thereof.
24. 24. The article according to any of claims 21-23 characterized in that the dispersant is selected from the group consisting of water-reducible alkyls, acrylics, polyesters, epoxides, and mixtures thereof.
25. 25. The article according to any of claims 21-24, characterized in that the water soluble polymer comprises about 10% to about 30% of the composition.
26. 26. The article according to any of claims 21-25 characterized in that opaque comprises approximately 5% to about 45% of the composition.
27. 27. The article according to any of claims 21-26 characterized in that the dispersant comprises about 0.5% to about 5.5% of the composition.
28. 28. The article according to any of claims 21-27 characterized in that it additionally comprises a colorant.
29. 29. The article according to any of claims 21-28 characterized in that the process employs a silicone transfer pad and wherein the composition additionally comprises a release agent.
30. 30. The article according to any of claims 21-29 characterized in that the composition essentially does not contain organic solvents.
31. 31. The article according to any of claims 21-30 characterized in that the article is a slow ophthalmic made of glass.
32. 32. The article according to claim 31, characterized in that the ophthalmic lens includes (i) a coating of abrasion resistance, (ii) an anti-reflection coating or (iii) both coatings of abrasion resistance and anti-reflection.
33. 33. The article according to any of claims 21-30 characterized in that the ophthalmic lens comprises two lens discs laminated together.
34. 34. The article according to claim 33, characterized in that the ophthalmic lens includes (i) an abrasion resistance coating, (ii) an anti-reflection coating or (iii) both abrasion resistance and anti-reflection coatings.
35. 35. The article according to claim 21, characterized in that the article is an ophthalmic lens made of plastic that is selected from poly (allyl diglycol carbonate), diacrylate, dimethylacrylate and polycarbonate.
36. 36. The article according to claim 35, characterized in that the ophthalmic lens includes (i) an abrasion resistance coating, (ii) an anti-reflection coating or (iii) both abrasion resistance and anti-reflection coatings.
37. 37. The article according to any of claims 35-36 characterized in that the ophthalmic lens comprises two lens discs laminated together.