GB2027641A

GB2027641A – Printing pad for the decoration of work pieces
– Google Patents

GB2027641A – Printing pad for the decoration of work pieces
– Google Patents
Printing pad for the decoration of work pieces

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Publication number
GB2027641A

GB2027641A
GB7927476A
GB7927476A
GB2027641A
GB 2027641 A
GB2027641 A
GB 2027641A
GB 7927476 A
GB7927476 A
GB 7927476A
GB 7927476 A
GB7927476 A
GB 7927476A
GB 2027641 A
GB2027641 A
GB 2027641A
Authority
GB
United Kingdom
Prior art keywords
pad
polymer
printing
printing pad
work
Prior art date
1978-08-16
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)

Granted

Application number
GB7927476A
Other versions

GB2027641B
(en

Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

BLYTHE COLOURS Ltd

Original Assignee
BLYTHE COLOURS Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1978-08-16
Filing date
1979-08-07
Publication date
1980-02-27

1979-08-07
Application filed by BLYTHE COLOURS Ltd
filed
Critical
BLYTHE COLOURS Ltd

1979-08-07
Priority to GB7927476A
priority
Critical
patent/GB2027641B/en

1980-02-27
Publication of GB2027641A
publication
Critical
patent/GB2027641A/en

1982-07-28
Application granted
granted
Critical

1982-07-28
Publication of GB2027641B
publication
Critical
patent/GB2027641B/en

Status
Expired
legal-status
Critical
Current

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Classifications

B—PERFORMING OPERATIONS; TRANSPORTING

B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS

B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM

B41N10/00—Blankets or like coverings; Coverings for wipers for intaglio printing

B41N10/02—Blanket structure

B—PERFORMING OPERATIONS; TRANSPORTING

B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS

B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM

B41N2210/00—Location or type of the layers in multi-layer blankets or like coverings

B41N2210/02—Top layers

B—PERFORMING OPERATIONS; TRANSPORTING

B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS

B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM

B41N2210/00—Location or type of the layers in multi-layer blankets or like coverings

B41N2210/14—Location or type of the layers in multi-layer blankets or like coverings characterised by macromolecular organic compounds

Abstract

For use in transferring a pattern in a medium such as ink from a plate on which the pattern is formed e.g. by silk-screen printing, to a work piece to be decorated with the pattern, a resiliently deformable solid convex printing pad of improved strength, improved stability to changes in humidity and temperature and improved resistance to attack by water-based inks is obtained by forming it of gelled plasticised vinyl polymer composition.

Description

SPECIFICATION
Printing pad for the decoration of work pieces.
e.g. by offset printing
This invention relates to the decoration of work-pieces, and especially although not exclusively articles of ware, particularly ceramic articles, and especially those in which the surface to be decorated is not flat, e.g. cups or plates.
It is already known to produce printed designs on the surface of work-pieces by off-set printing employing resiliently deformable pads which have been coated with the design in a suitable ink or other printing medium. For this purpose, a design is produced on the surface of a flat plate e.g. by inking an engraved surface of the plate or by applying the design to the surface by silk-screen printing; a solid resiliently deformable convex pad, which is generally shaped like an inverted bell or inverted dome with a somewhat parabolic or hemispherical contour, is pressed on to the surface of the plate carrying the design so that a central area of the pad makes contact with the plate first and the pad is then flattened on to the plate so that the whole design is imparted to the surface of the pad.The pad is then withdrawn from the plate so that it regains, or substantially regains, its natural shape, and then, still bearing the design, it is pressed on to the article to be printed. Again, a central area of the pad again makes contact first, and the pad is then flattened out on the surface of the article. In this way, the design on the surface of the plate and which has been picked up by the pad is now printed on the article. The pad is then withdrawn from the article, the plate is coated again with the printing medium, the pad is applied to it again, and so the process is repeated.
One such process, and apparatus therefor, is described in British Patent Specification 734637.
Examples of apparatus which employ the process are the Murray-Curvex machine, the Dekram machine and the Autoroll, Dubuit, Kaye-Dee and
Tampo-Print machines.
The pads can be as much as 12 inches (30 cm) or more in diameter and about the same in depth and can weigh as much as 20 kg. They are generally attached to rigid support plates to depend vertically downwards therefrom and are reciprocated in a vertical plane during use to pick up the design from the plate and imprint it on the article to be decorated. Thus, while they are required to be resiliently deformable, they must also be self-supporting and must not deform under their own weight while in operation.
Conventionally, the resiliently deformable pads are solid and moulded from a gelatine composition. However, gelatine has certain disadvantages:- it is not stable to heat, tending to melt above about 300 C, and will even flow when exposed to hot sunlight;
it is affected by moisture; if the ware being decorated breaks, the pad is damaged and must usually be replaced.
These disadvantages restrict the utility of the pad. For example, without employing a carefully controlled environment, it cannot be used in hot climates; indeed serious difficulties were encountered even in England in the hot summer of 1 976. Further, changes in atmospheric temperature and humidity can cause variations in the properties of the pads and affect print quality.
Moreover, because of gelatine’s sensitivity to moisture, water-based inks cannot be used and it is necessary to employ inks having a more expensive base, e.g. linseed oil.
More recently, there have been proposals to make the pad from silicone rubber. However, with many of the conventional inks, the pick-up of the ink by the silicone rubber pad is unsatisfactory. In some cases, also, ink attack on the silicone rubber pad has been observed. Thus, the use of such pads is necessitating the development of special inks.
The present invention provides pads which are stronger than gelatine pads, more stabie to changes in atmospheric temperature and humidity and less liable to attack by water-based inks, and with which the difficulties associated with the use of silicone rubber pads are reduced or eliminated.
Thus, according to the present invention, we provide a resiliently deformable solid convex printing pad for transferring a pattern in a printing medium such as ink from a plate on which the pattern is formed to a work piece which is to be decorated with the pattern, the pad being made of gelled plasticised vinyl polymer composition.
The invention also provides a method of applying a decorative design to a work-piece, preferably a ceramic work piece, by off-set printing, the method comprising pressing said pad against a surface of a flat plate bearing the design in ink to transfer the design to the pad and thereafter applying the design from the pad to the surface of the work-piece by pressing the pad carrying the design against the surface of the work-piece.
The invention further provides an apparatus for applying a decorative design to a work-piece by off-set printing, the apparatus including a flat plate to a surface of which a decorative design in ink may be applied, the resiliently deformable solid convex pad, a support for the work-piece, and means for pressing the pad alternately against said surface of the flat plate and a surface of a work-piece mounted on said support whereby to transfer an ink pattern from said flat plate to the surface of said work-piece.
The work-piece may be fiat or alternatively contoured as in a plate, cup or bowl. The invention is particularly suitable for decorating contoured work-pieces because the resilient deformability of the pad enables it to print reproducibly on to contoured surfaces.
The term “ink” as used herein means any coloured fluid composition employed for the production of patterns on work-pieces and particularly articles of ware.
The flat plate may, for example, be an intaglio plate to which the ink is applied in any suitable manner, e.g. by doctor-knife coating. Alternatively, the plate may have a plain surface of suitable material to which the decorative design is applied, e.g. by silk screen printing.
The pad will usually be generally inverted bellshaped or inverted dome-shaped with a parabolic or approximately hemispherical contour.
The pad may.suitably be prepared by forming a homogeneous mixture of plasticiser, vinyl polymer and, where required (e.g. where the vinyl polymer is a vinyl chloride polymer), stabiliser for the polymer, charging the composition into a suitably shaped mould and applying heat to gel the composition.
Preferably, the vinyl polymer, which may be a homopolymer of vinyl chloride or a copolymer from a copolymerisable mixture of monomers of
which the major constituent is vinyl chloride, 5 a s called “paste” polymer which is most preferably in the form of a spray-dried powder since this assists the admixture of the polymer with the plasticiser to achieve a uniform product. The vinyl chloride polymer may be polyvinyl chloride but is preferably a copolymer of vinyl chloride and vinyl acetate e.g. containing up to 15% and preferably about 2-1 0% by weight vinyl acetate, since plasticised forms of these copolymers are easier to gel.Polymers of high molecular weight are preferably avoided and it is preferred to use polymers of relatively moderate or low molecular weight e.g. corresponding to K values of about 40 to 80 preferably 60 to 70.
Any plasticiser which is known for the production of gelled plasticised vinyl polymer compositions may be used. Mixtures of plasticisers may also be used. However, plasticisers or mixtures thereof should be avoided which have a tendency to sweat out of the gelled composition when pressure is applied to the composition since such sweating tends to impair the quality of the printing. Where the polymer is a vinyl chloride polymer, the dialkyl phthalate plasticisers, especially di isodecyl phthalate, are preferred.
The softness of the pad will be determined primarily by the amount of plasticiser employed in the composition, and accordingly the degree of softness can be controlled by adjustment of the amount of plasticiser used. The amount of plasticiser employed will depend upon the nature of the plasticiser and the degree of softness required but will generally be within the range 120 to 300 parts per 100 parts by weight of polymer.
Above 300 parts of plasticiser, the gelled composition will generally be too soft and insufficiently strong and pads formed of it may tend to deform under their own weight. With less than 120 parts by weight on the other hand, the composition tends to be too hard for the pads to be used with conventional machinery and under conventional conditions. For the preferred dialkyl phthalate plasticisers, the preferred range is 1 50 to 280 parts per 100 parts of polymer, particularly 180 to 280 parts.
Of course, as is conventional, it is desirable to include a heat stabiliser in a plasticised vinyl chloride polymer composition. The amounts required are those ,eonventionally used. The particular amount used will depend upon the
nature of the stabiliser but must be such as to
permit gellation of the composition to be completed without degradation of the composition occurring. Degradation is generally accompanied by embrittlement and possibly some foaming and evolution of hydrogen chloride gas.
Discoloration also occurs but discoloration alone, although undesirable, can be tolerated provided there is no unacceptable deterioration in physical properties. In general the amount of stabiliser required will be from 1 to 5 parts per 100 parts of polymer, and usually about 2 parts.
Any stabiliser normally used for gelled plasticised vinyl chloride compositions may be used. Mixtures of such stabilisers may also be used. However, it is preferred to use a stabiliser which does not sweat from the gelled composition when pressure is applied to the composition since such sweating tends to impair the quality of the printing. Preferred stabilisers are those based on tin, especially mercapto tin compounds, e.g.
dibutyl thiotin compounds.
In- mixing the plasticiser, stabiliser and polymer to form the composition, a suitable procedure is first to mix in a small amount of the plasticiser and then to add the remainder. Care should be taken to avoid entrapment of air and it is preferred to degas the composition, e.g. by evacuation, prior to gelling it, to avoid bubbles in the gel.
The temperature required for gelation will depend upon the amount of plasticiser used, the nature of the plasticiser and the nature of the vinyl polymer. The deformable pads may be up to as much as 12 inches (30 cm) in diameter and the same in length and weight up to 20 kg or more, and it is surprising that such pads can be made satisfactorily from a plasticised vinyl polymer composition. It was not to be expected that an object having such dimensions could be satisfactorily gelled through to the core without thermal damage to the surface material, it being well known that vinyl chloride polymers are particularly sensitive to heat.I have found, however, that by careful control of the heating it is possible to produce such articles satisfactorily from plasticised vinyl chloride polymer compositions without degrading the surface of the article to an unacceptable degree although some discoloration, which is not in itself unacceptable, may occur in some cases. I have found that satisfactory results may be obtained provided gel temperatures of not more than about 1 800C are used. On the other hand, if the temperature is below 100 to 11 OOC, gelling will not occur or will not occur within a reasonable time. Best results are obtained at temperatures of about 140 to 1500 C.
The time required for gelation will depend upon the size and shape of the pad and the temperature employed. It will increase with increase in the dimensions of the pad and with decrease in the temperature employed. In general times in the range of from 2 to 20 hours are required with times of
from about 4 to 12 hours at the
preferred temperatures of 140 to 1 500C for pads
having diameters in the range 8-12 inches (20–30 cm).
In one preferred method, the mixture is formed
and then charged into a suitably shaped mould
which is then placed in an oven which is
preheated to the desired temperature. For this
method, the mould is preferably of a material,
such as metal, which is a good conductor of heat but other materials, e < ,q. plass, may be used. To assist heat transfer during gelation, it is preferred to stir the mixture thoroughly in the mould after heating of the composition has commenced but before the temperature of gelation has been attained. A suitable temperature range for carrying out this stirring step is 50 800 C. After gelation is complete, the moulded pads are cooled to room temperature. Depending on the size of the pad, this may require up to 10 hours or even more. The pad should not be removed from the mould until it is sufficiently cool to be selfsupporting and not deform under its own weight. The degree of softness required in the pad will vary with its intended use; the smaller the radius of curvature of the article to be decorated, the softer the pad required. The pad may be attached to the support plate in any suitable manner, e.g. by adhesive or by fasteners such as screws. A suitable adhesive is Ciba Geigy AV 138. A more satisfactory means, however, is to anchor a plate to the pad during its formation, the plate being provided with means, e.g. tapped holes, permitting its ready attachment to the base plate by means of conventional fasteners. In one preferred embodiment, a flat metal plate, e.g. of aluminium, which has dimensions slightly smaller than those of the top end of the pad, is provided with lugs which extend outwardly from one face of the plate and which include, spaced from the plate, sections of larger cross sectional area than those adjacent the plate. The plate is also provided with means such as described above for permitting its attachment to the base plate by conventional means. The plate is located in the mould on top of the composition and with the surface of the plate in contact with the top surface of the composition and the lugs extending into the composition, after the composition has been charged to the mould. Gelling the composition locks the lugs into the body of the composition and provides a firm and secure means of fixing the pad to the plate. The pads of the invention are not noticably attacked by water and can therefore be used with water-based inks and are not sensitive to changes in atmospheric humidity. They also have generally greater dimensional stability at elevated temperatures than gelatine pads, the degree of dimensional stability depending primarily upon the amount of plasticiser present, the greater concentrations of plasticiser resulting in reduced dimensional stability. Thùs, by means of the invention pads may be produced which are not deformed by exposure to direct sunlight and can be used successfully in tropical climates. Unlike silicone rubber pads, the pads of the present invention operate satisfactorily with conventional inks, and it is not necessary to use specially formulated inks. By varying the concentration of plasticiser in the composition from which the pad is formed, pads of various degrees of softness may readily be prepared. By means of the invention, it is also possible to produce pads which are stronger than conventional gelatine pads and therefore less prone to damage in use. The invention is now illustrated but in no way limited by the following Example. EXAMPLE A gellable plasticised vinyl chloride composition was prepared by mixing together the following (all parts are by weight). Polymer:A spray-dried pdwder copolymer of vinyl chloride and vinyl acetate containing 2% vinyl acetate and marketed by Imperial Chemical Industries Limited as Corvic P67/668. 100 parts Plasticis.er: Di-isodecyl phthalate marketed by Alright and Wilson as "Pliabrac" DIDP. 240 parts Stablliser: Dibutyl Thiotin Stabiliser containing 1516% Sn and 8-9.9% mercapto sulphur and marketed by Albright and Wilson as "Mellite" 31. 2 parts The polymer and a small portion of the plasiser were initially mixed together and then the remainder of the plasticiser and all the stabiliser added in.The mixture was then de-gassed by placing it in a closed container and evacuating it to a few mm of mercury absolute pressure employing a two-stage oil pump. The degassed mixture was then poured into a bell-shaped aluminium mould having a maximum diameter at its mouth of 10 inches (25 cm) and a depth of 9 inches (23 cm). About 10 kg of composition was required. The mould was placed in an oven pre-heated to 1 450C and gelling required 10 hours dwell time in the oven at that temperature. When the composition had reached about 600C, it was stirred to assist heat transfer during gelling. After removal from the oven, the mould was allowed to cool in air for 1 5 hours and the gelled pad was then removed from the mould. It was a strong and resiliently flexible moulding with an excellent finish and a generally creamy colour tending towards orange at its maximum diameter and had about the same softness as a conventional gelatine pad. It was attached to a conventional base plate of a Murray Curvex machine by means of a Ciba-Geigy AV 138 adhesive and used in a manner conventional for gelatine pads for decorating ware with a conventional linseed-oil based ink. Ink pick-up was excellent and printing was still satisfactory after 400 and 1000 cycles. The pad was not noticably affected by moisture or by exposure to direct sunlight. Its rate of recovery during the printing cycle was excellent in that it was not so fast that bouncing occurred but rapid enough to have fully recovered between cycles. Sectioning of the pad showed that it was fully gelled through to the core. Claims (21) 1. A resiliently deformable solid convex printing pad for transferring a pattern in a printing medium such as ink from a plate on which the pattern is formed to a work piece which is to be decorated with the pattern, the pad being made of gelled plasticised vinyl polymer composition. 2. A printing pad as claimed in claim 1 wherein the vinyl polymer is a paste polymer. 3. A printing pad as claimed in claim 2 wherein the vinyl polymer is in the form of a spray dried powder. 4. A printing pad as claimed in any one of claims 1 to 3 wherein the vinyl polymer is a copolymer of vinyl chloride and vinyl acetate. 5. A printing pad as claimed in claim 4 wherein the copolymer contains 2 to 10% by weight of vinyl acetate. 6. A printing pad as claimed in any one of claims 1 to 5 wherein the vinyl polymer has a molecular weight corresponding to a K value of 40 to 80. 7. A printing pad as claimed in any one of claims 1 to 6 in which the composition contains 120 to 300 parts of plasticiser per 100 parts of polymer, by weight. 8. A printing pad as claimed in any one of claims 1 to 7 wherein the vinyl polymer is a vinyl chloride polymer and the plasticiser is selected from dialkyl phthalate plasticisers. 9. A printing pad as claimed in claim 8 wherein the plasticiser is di-isodecyl phthalate. 10. A printing pad as claimed in claim 8 or claim 9 in which the composition contains 1 50 to 280 parts of plasticiser per 100 parts of polymer, by weight. 11. A printing pad agclaimed in any one of claims 1 to 10 in which the polymer is a vinyl chloride polymer and the composition includes a heat stabiliser for the polymer in an amount of 1 to 5 parts per 100 parts of polymer, by weight. 12. A printing pad as claimed in claim 11 wherein the heat stabiliser is a mercapto tin compound. 13. A printing pad as claimed in claim 1, substantially as hereinbefore described. 14. A method of making a printing pad as claimed in any one of claims 1 to 13, the method comprising forming the mixture comprising vinyl polymer and, plasticiser and optional heat stabiliser, charging said mixture to a suitably shaped mould and then heating the mixture to 100 to 1 800C until it is gelled. 15. A method as claimed in claim 14 in which the mixture is heated to 140 to 1 500C. 1 6. A method as claimed in claim 14 or claim 15 in which the mixture is de-gassed prior to gelling. 17. A method as claimed in any one of claims 14 to 1 6 in which the mixture is stirred in the mould at a temperature of 500C to 800C prior to gelling. 18. A method as claimed in claim 14, substantially as hereinbefore described. 19. A printing pad obtained by the method of any one of claims 14 to 18. 20. A method of applying a decorative design to a work piece by off-set printing, the method comprising pressing a printing pad as claimed in any one of claims 1 to 13 and 19 against a surface of a flat plate bearing the design in ink to transfer the design to the pad and thereafter applying the design from the pad to the surface of the work piece by pressing the pad carrying the design against the surface of the work-piece. 21. Apparatus for applying a decorative design to a work-piece by off-set printing, the apparatus including a flat plate to a surface of which a decorative design in ink may be applied, a resiliently deformable solid convex pad, as claimed in any one of claims 1 to 13 and 19, a support for the work-piece, and means for pressing the pad alternately against said surface of the flat plate and a surface of a work-piece mounted on said support whereby to transfer an ink pattern from said flat plate to the surface of said work-piece. GB7927476A 1978-08-16 1979-08-07 Printing pad for the decoration of work pieces Expired GB2027641B (en) Priority Applications (1) Application Number Priority Date Filing Date Title GB7927476A GB2027641B (en) 1978-08-16 1979-08-07 Printing pad for the decoration of work pieces Applications Claiming Priority (2) Application Number Priority Date Filing Date Title GB7833555 1978-08-16 GB7927476A GB2027641B (en) 1978-08-16 1979-08-07 Printing pad for the decoration of work pieces Publications (2) Publication Number Publication Date GB2027641A true GB2027641A (en) 1980-02-27 GB2027641B GB2027641B (en) 1982-07-28 Family ID=26268560 Family Applications (1) Application Number Title Priority Date Filing Date GB7927476A Expired GB2027641B (en) 1978-08-16 1979-08-07 Printing pad for the decoration of work pieces Country Status (1) Country Link GB (1) GB2027641B (en) 1979 1979-08-07 GB GB7927476A patent/GB2027641B/en not_active Expired Also Published As Publication number Publication date GB2027641B (en) 1982-07-28 Similar Documents Publication Publication Date Title CA1076735A (en) 1980-04-29 Plastisol composition and container closure gasket made therefrom US3007829A (en) 1961-11-07 Vitreous decalcomania US2629134A (en) 1953-02-24 Method of manufacturing articles from vinyl resins US3293728A (en) 1966-12-27 Ink applying roller and process of preparation thereof US2525966A (en) 1950-10-17 Treatment of expanded articles US2279774A (en) 1942-04-14 Coated product US2447056A (en) 1948-08-17 Manufacture of expanded thermoplastic materials KR20000075899A (en) 2000-12-26 Molded polytetrafluoroethylene article and method of production thereof US3347971A (en) 1967-10-17 Rotational molding US3557030A (en) 1971-01-19 Gasket-forming compositions for closure elements CN110395968A (en) 2019-11-01 Magnesia heat-resisting casserole GB2085805A (en) 1982-05-06 Printing medium for use with silicone transfer members GB2027641A (en) 1980-02-27 Printing pad for the decoration of work pieces US2753314A (en) 1956-07-03 Composition comprising a gelling agent and a dispersion of a vinyl resin in a plasticizer US4684548A (en) 1987-08-04 Method for modifying the surface state of materials CN109825187A (en) 2019-05-31 A kind of insulating moulding coating and preparation method US3639507A (en) 1972-02-01 Plastic pattern material for investment casting GB2267675A (en) 1993-12-15 Rotational moulding of two-colour products JPS6090221A (en) 1985-05-21 Production of vinyl chloride based resin composition for sintering powder US3044124A (en) 1962-07-17 Rotational casting HUT72759A (en) 1996-05-28 Gelled reactive resin compositions US4882102A (en) 1989-11-21 Process for producing hard carbonaceous sheets JP3321048B2 (en) 2002-09-03 Continuous porous elastic body US2965509A (en) 1960-12-20 Thermofluid vehicles DE3067369D1 (en) 1984-05-10 Process for producing shaped erasers Legal Events Date Code Title Description 1984-04-04 PCNP Patent ceased through non-payment of renewal fee
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