Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/02—Printing inks
  • C09D11/10—Printing inks based on artificial resins
  • C09D11/106—Printing inks based on artificial resins containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M1/00—Inking and printing with a printer's forme
  • B41M1/26—Printing on other surfaces than ordinary paper
  • B41M1/32—Printing on other surfaces than ordinary paper on rubber

Definitions

• a method for printing images on a latex rubber surface which comprises applying an ink containing natural or synthetic rubber, pigment dispersion, and a solvent medium in particular an aromatically unsaturated solvent medium for said rubber.
• the ink may additionally comprise an aryl diisocyanate.
• the aryl diisocyanate may be either in the base coat or the ink.
• a base coat of natural rubber in such a solvent is required, where the rubber in the ink is synthetic rubber.
• the aryl diisocyanate may be either in the base coat or the ink.
• a portion of the solvent may be replaced by a terpene, a terpenoid or a high boiling ketone suitably having a boiling point over 120°C, such as isophorone or the like.
• the efficacy of the printing may be improved by certain pre- and post- printing steps.
• One such additional step is heating the printing surface.
• Another, highly desirable, added step is placing a base coat upon the printing surface that receives the image.
• this base coat is allowed to dry to tackiness before the image is printed.
• this base coat comprises natural rubber in an aromatically unsaturated solvent.
• a critical feature of the invention is the presence of an agent capable upon cure, of forming a chemically and abrasion resistant, tough flexible structure integrating the rubber of said base coat, where it is present, the rubber of the ink , together with the pigment therein, and the rubber of the latex surface, in at least one of the base coat and the ink.
• an agent capable upon cure of forming a chemically and abrasion resistant, tough flexible structure integrating the rubber of said base coat, where it is present, the rubber of the ink , together with the pigment therein, and the rubber of the latex surface, in at least one of the base coat and the ink.
• an agent is an aryl diisocyanate.
• the integrating agent may be in either the ink phase and/or the base coat.
• the ink as well as the base coat may be applied using a number of common printing techniques including: gravure printing, flexo printing, screen printing, and pad printing.
• Pad printing howeverl has been found to be superior for the inventive purposes, such as: printing individual rubber articles like rubber gloves.
• DESCRIPTION OF THE PREFERRED EMBODIMENTS There is provided a method and a formulation for printing images on latex rubber surfaces. It is desirable that the weight amount of the aryl diisocyanate is between 0.5 and 3.0 times that of the total rubber in solution within the ink or within the base coat where used or both.
• the rubber may be natural rubber or synthetic rubber.
• the diisocyanate is selected from the group consisting of toluene -, methylene diphenyl- and polymeric methylene diphenyl diisocyanates, and mixtures thereof.
• the rubber in the ink may be natural rubber or synthetic rubber such as neoprene rubber or blends thereof.
• the ink at printing time, should have a viscosity at 20°C of between 800 and 3000 cps.
• the use of synthetic rubber in the ink is preferred over natural rubber since its chemical resistance is greater.
• natural rubber when mixed with aryl diisocyanate will provide sufficient resistivity.
• Aryl diisocyanate when cured per se will form a hard brittle product, In the presence of rubber, it becomes integrated therewith to yield a flexible, tough, and chemically resistant structure or matrix, that provides the unique printing product associated with this invention.
• Inks containing the diisocyanate should be promptly used after mixing, suitably within 10 hours of preparation.
• Prior art printing solvents generally use mineral spirits, such as: aliphatic or alicyclic hydrocarbons.
• the solvents used in the inks and precoat of the invention are aromatically, unsaturated solvents.
• Aliphatic esters of aromatic acids, or higher liquid aromatic hydrocarbons are preferred.
• methyl naphthalene is preferred.
• the latter may, under certain conditions, be partially replaced with terpenes, or terpenoids, such as: dilimonene, or high boiling ketones, such as: isophorone.
• the methyl naphthalene is preferred.
• Glidsol 90 manufactured by SCM Glisol Organics, 210 Summit Ave., Montvale NJ 07645, is a terpene formulation that is especially preferred.
• Terpenes and terpenoids can be used in the base coat, but this is not preferred. It should be noted, that commercial methyl naphthalene, is in fact, a complex mixture containing dimethyl naphthalene, ethyl methyl naphthalene, and other heavy, fractional coal tar components.
• the actual amounts of rubber, solvents, and pigments used in the printing formulations of this invention may vary quite substantially depending on the desired consistency and drying speed.
• the desired ink viscosity range at 20°C, is approximately between 800 and 3,000 cps. Approximately between 5 and 40 wt% of pigment is contained in the ink composition.
• the image to be printed on a latex rubber surface in accordance with the ink formulation of this invention is not particularly dependent upon any conventional printing method. Stability of the image is improved by the additional step of heating the printed surface. Suitably, the heating is accomplished in a temperature range of from approximately 95 to 130°C. for 10 to 20 minutes, or approximately from 190 to 230°C. for 3 to 8 seconds.
• Heat curing can increase the chemical and abrasive resistance of the printed ink image to the commonly used, household cleaner, Pine Sol ® .
• a simple test of ink image endurance is to rub the printed image with a pad impregnated with Pine Sol at recommended, household detergent strength.
• Resistance of Neoprene, and natural rubber-containing inks of this invention are capable of withstanding 35 to 100 rubs. This is achievable with the inventive ink formulations due to the presence of the aryl diisocyanate, which as aforementioned, intimately embeds within the rubber molecules.
• the resistance of the printed image may also be improved by certain pre-, and post-printing steps.
• washing the surface of the article with water and surfactant, followed by drying; or just washing the surface with a hydrocarbon solvent, will improve the printing process.
• the washing procedure is not recommended for gloves containing flock on their inner surfaces. Heating the printed image for approximately 3 to 6 seconds at approximately between 190-220°C, is helpful.
• One of the unusual, and totally unexpected aspects of this invention is the ability of the printed image product to become increasingly resistant to chemical attack and abrasion with time. It has been observed that while the printed image product is contact stable immediately after the initial heating step, the resistance to chemical abrasion continues to build towards a maximum over an extended period at ambient temperature. Testing reveals that the printed image product reaches maximum efficacy between 20 and 60 days after printing. This slow cure does not pose a marketing problem, however, because the mean time between manufacture and the arrival at the point of sale of a typical printed latex rubber glove, is usually about 75 days.
• Printed image stability is also improved by placing a base coat upon the surface receiving the printed image.
• the base coat is applied and allowed to dry until tacky.
• the image is then printed upon the tacky base coat surface.
• the base coat can comprise natural rubber in an aromatically unsaturated solvent.
• this base coat also contains an aryl diisocyanate, in an approximate weight amount of between 0.5 and 3.0 times that of the rubber in solution.
• One method of printing an image on a latex rubber surface includes preparing a clear base coat solution, comprising natural rubber of approximately one to ten parts by weight in an aromatic hydrocarbon solvent of approximately 45 to 50 parts by weight.
• This clear base coat solution is then admixtured with a premixed moiety comprising an aromatic hydrocarbon solvent of approximately between 2 to 15 parts by weight containing an aryl diisocyanate of approximately 1 to 30 parts by weight.
• the above admixture is then mixed with a pigment having an approximate weight of between 0.3 to 5.0 times that of the rubber in solution.
• the components of this formulation, viz., the clear coat, the premix, and the pigment are mixed at ambient temperature, and then printed upon the latex rubber surface preferably within 10 hours of the mixing.
• a generally preferred method of printing an image on a latex rubber surface comprises the step of applying a base coat to the rubber surface containing natural rubber in approximate range by weight of between 5 to 15 parts in a solvent approximately ranging in weight between 80 to 120 parts, and an aryl diisocyanate ranging in weight between 0 to 45 parts.
• the image is then printed onto the base coat utilizing an ink whose formulation comprises natural or synthetic rubber in approximately 1 to 10 parts by weight; a rubber solvent in the approximate weight of between 30 to 60 parts; a pigment of approximately 0.3 to 5.0 times the weight of the rubber; and an aryl diisocyanate in the weight range of approximately 0 to 30 parts.
• the rubber solvent in the aforesaid formulation can be an aromatic hydrocarbon, a terpene, a terpenoid, a ketone boiling above 120°C, or a mixture thereof.
• the rubber solvent in the base coat may be an aromatic hydrocarbon solvent comprising approximately 60 to 90 parts by weight, a terpene, or terpenoid solvent in approximate weight of between 0 to 60 parts.
• the rubber solvent in the ink may be an aromatic hydrocarbon solvent comprising approximately 30 to 50 parts by weight, and a terpene or terpenoid solvent of approximately 0 to 30 parts by weight.
• Various combinations of base coat and ink compositions are within the scope of the present invention.
• the ink comprises synthetic rubber in approximately 1 to 10 parts by weight; an aromatic hydrocarbon solvent in about 30 to 80 parts by weight; and a pigment that is 0.3 to 5 parts by weight.
• the base coat can comprise natural rubber in approximate weight of between 5 to 15 parts; an aromatic hydrocarbon solvent in approximately 80 to 120 parts by weight; and an aryl diisocyanate in approximate weight of between 1 to 45 parts.
• the ink comprises synthetic rubber in approximate weight of between 1 to 10 parts; an aromatic hydrocarbon solvent of approximately 30 to 60 parts by weight; a pigment in approximate weight of between 0.3 to 5.0 parts; and an aryl diisocyanate approximately 1 to 30 parts by weight.
• the base coat can comprise natural rubber approximately 5 to 15 parts by weight in an aromatic hydrocarbon solvent comprising approximately 80 to 120 parts by weight.
• the ink comprises synthetic rubber in about 1 to 10 parts by weight; an aromatic hydrocarbon solvent approximately 15 to 60 parts by weight; a terpene, or terpenoid solvent in approximate weight range of 5 to 40 parts; and a pigment approximately 0.3 to 5.0 parts by weight.
• the base coat comprises natural rubber approximately between 5 to 15 parts by weight; an aromatic hydrocarbon solvent in an approximate weight range of between 80 to 120 parts; and an aryl diisocyanate of about 1 to 45 parts by weight.
• the ink comprises synthetic rubber in approximate weight range of 1 to 10 parts; an aromatic hydrocarbon solvent of about 15 to 60 parts by weight; a terpene, or terpenoid solvent of approximately 5 to 40 parts by weight; a pigment in a weight range of between 0.3 to 5.0 parts, and an aryl diisocyanate in approximate weight of between 1 to 30 parts.
• the base coat comprises natural rubber from approximately 5 to 15 parts by weight in an aromatic hydrocarbon solvent of about 80 to 90 parts by weight.
• aromatic hydrocarbon of choice in the above formulations is commercial grade methyl naphthalene.
• a series of printing stations each comprise pad printer.
• the printing stations are aligned to provide sequential processing.
• a first printing station is charged with the base coat, and the pigmented printing ink is charged to the second printing station.
• a number of colors may be printed by placing additional pad printing stations in line all subsequent to the first base coat printer. It has been found that improved results are obtained by not allowing the base coat to thoroughly dry before the pigmented ink is applied .
• a slight base coat tackiness should remain as the rubber glove passes under subsequent print stations.
• Heat is applied to the print surface by contact heating with a teflon coated aluminum plated heater to an approximate temperature of 215°C. for five seconds. The heating procedure assists in the cure of the printing ink, which effects its ability to resist chemical attack and abrasion.
• DABCO T-12 (Dibutyltin Dilaurate): Air Products & Chemicals Inc.
• PAPI 2021 polymethylene polyphenyl isocyanate mfg. by Dow Chemical Company, Plastics Div., Midland Ml.
• Di-XXXX Pigments 25% Pigment, 75% Dinonyl Phthalate; Mfg by Cardinal
• NEOPRENE GW Dupont Co., Elastomer Div., Wilmington DE
• Example I A printing ink is prepared as follows:
• Agerite Stalite 0.34 Total 120 An image was imprinted upon a latex surface using the above formulation. The aforementioned rubbing test was performed using pads impregnated with Pine Sol ® . The test was conducted 12 days after printing.
• the printed image was air cured. Only one rub was required to remove the image.
• Example II In the ink formulation given in Example I, 17 parts of PAPI 2020 were added to the ink. After printing an image upon a latex surface, a Pine sol ® test was performed after 12 days. The printed image was air cured at ambient. It required 6 rubs to erase the image.
• Example III A base coat is prepared as follows: PARTS *
• Example II The above base coat was applied to a natural rubber surface just prior to application of the ink shown in Example II.
• a Pine sol ® rubbing test was performed after 12 days. It took approximately between 12 to 22 rubs to remove the printed image. This test was additionally performed using a cure of 60 days. The image required 40 rubs for removal.
• Example IV Natural rubber ink To the composition of Example III was added PAPI 2020 8 parts Blue Di-61 12 20 parts The Pine sol ® rubbing Test was performed after the printed image was allowed to cure for 9 days. The image was removed after 16 rubs.
• Example V An ink of Example IV was applied over a base coat of Example II.
• PAPI 2020 (Premix) 0.5 3.0 15.0
• PAPI 2020 (Premix) ... 0.5 3.0 1 5.0
• Curing Time was 60 days.
• a rubbing Pine sol ® test required 40 rubs to remove the printed image.
• Example X
• PAPI 2020 (Premix) 1.0 6.0 12.0
• Neoprene-PAPI 2020 8.85:1.0 1 .42:1.0 0.71 :1 .0

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)
• Printing Methods (AREA)
• Paints Or Removers (AREA)

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Family Applications (1)

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Cited By (44)

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Citations (3)

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• 1996
  • 1996-01-05 EA EA199700099A patent/EA000164B1/ru not_active IP Right Cessation
  • 1996-01-05 AU AU46949/96A patent/AU703440B2/en not_active Ceased
  • 1996-01-05 JP JP8521749A patent/JPH11501337A/ja active Pending
  • 1996-01-05 EP EP96902610A patent/EP0802953A2/de not_active Withdrawn
  • 1996-01-05 WO PCT/US1996/000163 patent/WO1996021701A2/en not_active Application Discontinuation
  • 1996-01-05 CN CN96192238A patent/CN1176652A/zh active Pending
  • 1996-01-05 CA CA002211017A patent/CA2211017A1/en not_active Abandoned
  • 1996-01-05 BR BR9606896A patent/BR9606896A/pt active Search and Examination
  • 1996-01-06 TW TW085100133A patent/TW325444B/zh active
  • 1996-01-07 IL IL11669096A patent/IL116690A/xx not_active IP Right Cessation
  • 1996-01-08 ZA ZA9693A patent/ZA9693B/xx unknown
  • 1996-01-09 AR AR33496196A patent/AR000644A1/es unknown

Patent Citations (3)

Non-Patent Citations (1)

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