CA1125089A - Compressible composite flexographic plate - Google Patents
Compressible composite flexographic plateInfo
- Publication number
- CA1125089A CA1125089A CA347,426A CA347426A CA1125089A CA 1125089 A CA1125089 A CA 1125089A CA 347426 A CA347426 A CA 347426A CA 1125089 A CA1125089 A CA 1125089A
- Authority
- CA
- Canada
- Prior art keywords
- layer
- printing
- rubbery material
- printing plate
- plate
- Prior art date
- 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.)
- Expired
Links
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
- B41N1/00—Printing plates or foils; Materials therefor
- B41N1/12—Printing plates or foils; Materials therefor non-metallic other than stone, e.g. printing plates or foils comprising inorganic materials in an organic matrix
Abstract
Abstract of the Disclosure A compressible composite relief type printing plate has a layer of relatively hard rubbery material having an outer printing surface and an inner support surface, a layer of relatively soft rubbery material having one surface which is discontinuous in the periph-eral direction to provide a plurality of spaced pro-jections integral with the soft rubbery material and of substantially the same height to define a mounting surface, and an adhesive securing the mounting surface to the support surface. The compressibility feature permits absorption of excess pressures exerted against the ink transfer image producing lands of the printing plate so that the integrity of the amount and size of images transferred to the surface being printed remains sub-stantially constant even though the thickness thereof may vary up to 0.005 inch in random patterns.
Description
.
~Z5~
SUN 118 (RUTH) ' COMPRESSIBLE CO~IPOSITE PRINTING PLATE
. . . ~ , . . . _ Back~round of the InYention Many surfa~ss which require being printed or decora~ed for identification, sales, or other purposes are not smooth and are not always of uni~orm thicknesses.
In some printing processes, such as lithographic offset, dry of~set, gravure, or letter press printing, the uneven-ness is sometimes overcome by using substantial printing pressure to press into the substrate and thereby momentarily squeeze and relocate the unevenness, or, in the case o of ~set, to absorb the unevenness into the rubber blanket which carries the image area inX to the substrate.
An increase in printing pressure is not possible in-printing ~here the plate material is relatively - soft, often having a durometer range of about 65-100, The plate material is softer than the substrate being printed upon a~d the plate itself ~ill be compressed or squ~ezed, which caus~s an undesirable de~ormation or growth in the area o~ the image being printed.
,' ' , ~. .
'' ' . '':' - , -....
.
~ ,:
25~i~9
~Z5~
SUN 118 (RUTH) ' COMPRESSIBLE CO~IPOSITE PRINTING PLATE
. . . ~ , . . . _ Back~round of the InYention Many surfa~ss which require being printed or decora~ed for identification, sales, or other purposes are not smooth and are not always of uni~orm thicknesses.
In some printing processes, such as lithographic offset, dry of~set, gravure, or letter press printing, the uneven-ness is sometimes overcome by using substantial printing pressure to press into the substrate and thereby momentarily squeeze and relocate the unevenness, or, in the case o of ~set, to absorb the unevenness into the rubber blanket which carries the image area inX to the substrate.
An increase in printing pressure is not possible in-printing ~here the plate material is relatively - soft, often having a durometer range of about 65-100, The plate material is softer than the substrate being printed upon a~d the plate itself ~ill be compressed or squ~ezed, which caus~s an undesirable de~ormation or growth in the area o~ the image being printed.
,' ' , ~. .
'' ' . '':' - , -....
.
~ ,:
25~i~9
-2-Various methods have been devised for use in printing to overcome the problems of uneven surfaces and uneven thic~nesses with their resulting deformation or "cupping" of the printed material. One such device is a resilient printing plate described in U.S. Patent 3,425,347, a cross-section of which is set forth in Figure 1 here~f. Such printing p.late includes a curved metallic backing member 1 usually made of brass - and a layer of soft rubber 2 whose surface contacting the backing member is discontinuous so as to provide a plurality of uniformly spaced projections 3 and the other surface being connected to a layer of a hard rubber 4 which has an outer printing surface 5. The printing plate is made by partially vulcanizing rubber layers 2 and 4 together in a molding.press, cooling the resulting plate, afix;ng the soft rubber plate to the metallic backing material and then cpmpleting the curing process~ The combination of the spaced projections and the procedure of partially curing the rubber plate ~ith the subsequent co~npletion of the ..
curing process after the plate has been mounted on the bac~ing material is said to substantially reduce cupping of the printed sur~ace normally e:ncountered in bending a fully cured rubber plate. When heat is applied to the partially cured rubber in the curved position during the Z5 second curin~ operation, the nerve or memory of $he rubber formula is relaxed and sets to the diameter of the curve.
The projections 3 are positioned on the surface furthes~ -from the printing surface 5 i~ order to compensate ~or any compression generated throughout the entire thickness of the rubber body.
:
~.~2~
curing process after the plate has been mounted on the bac~ing material is said to substantially reduce cupping of the printed sur~ace normally e:ncountered in bending a fully cured rubber plate. When heat is applied to the partially cured rubber in the curved position during the Z5 second curin~ operation, the nerve or memory of $he rubber formula is relaxed and sets to the diameter of the curve.
The projections 3 are positioned on the surface furthes~ -from the printing surface 5 i~ order to compensate ~or any compression generated throughout the entire thickness of the rubber body.
:
~.~2~
-3-The resilient printing plate of Patent 3,425,347 involves a number of inconveniences. These result from the fac~ that the rubber layers 2 and 4 must be jointly partially cured and completion of the vulcanization of the composite rubber structure must be accomplished a~ainst a curved metallic bacXing surface, The individual hard prin~ing layer and soft cushioning layer cannot be separately produced and particularly an inventory o so~t cushion layer 2 cannot be maintained.
Additionally, the required use o~ the curved metallic backing layer 1 requires that *he metallic material be dedicated to this purpose.
Accordingly, it is the object of this invention to provide an improved printing plate which will produce a high fideli~y and sharpness in printing without haloing, cupping, unevenness, or other imperfections which can be produced without requiring a special partial cure subsequent cure procedure 9 or the use of a dedicated curved or 1at backing material or any special backing material. This and other objects of the invention will become apparent from the follo~ing detailed description in conjunction with the drawings of which Figure 1 is a cross-section ~f a printing plate of the prior art as heretofore described;
Figure 2 is a cross-section of a printing plate produced in accordance with the present invention;
Figure 3 is a plan vie~ of a section of the soft ~ushion layer of the instant printing plate; and Figure 4 is a plan view, partially cut away, of one embodiment of a printing plate in accordance with the present invention.
`"' `~:
5`~8~3 SU~I~IARY OF Tl-IE INVENTION
This invention relates to a compressible composite relief type printing plate and more particularly to relatively soft letter press type relief printing plates such as flexographic printing plates. The printing plate has a layer of a relatively hard rubbery material haviIlg an outer printing sur~ace and an inner support surface, a layer of a relatively so~t rubbery material having a surface which is discontinuous in the peripheral direction to provide a plurali~y of spaced projections integral wi~h the soft rubbery material and of substantially the same height to define a mountin~ surface, the mount;ng surface and the inner support surface being secured to-gether by an adhesive. The compressibility of the plate permits it to absorb excess pressures exerted against tlle ink ~ransfer image producing lands o-~ the printing plate so t}-at the integrity of the amount and size of images ~rans~erred to t}le surface being printed remains sub-stantially constant even though the thickness thereo~
may vary up to 0.008 inch in random patterns.
DESCRIPTION OF I'~-IE INVENTION
With reference to Figures 2, 3 and 4, the printing plate 101 has two layers 102, 103 o rubber-li~e material. Any oE the rubbery materials heretoore used ~or printing plates can be used to make layers 102 and 103. For e~ample, the rubber-like material can be natural rubber, butyl rubber, ethylene-propylene rubber, and the li~e, or harder materials such as the photo-~ polymers or "Dycril~ Such materials must be moldable and, in the case o~ the rubber and soft pla5tic com~ounds,capable of being vulcanized. As is conventional, the .
- s -rubbery material of prin~ing layer 10~ is harder relative to the rubbery material of cushion layer 103. For example, layer 102 can have a durometer rating of 50 to 90 while cushion layer 103 has a durometer rating of Z0 to 30.
Printing layer 102 is -formed by melting a suitable moldable relatively hard rubbery material in a mold which is the mirror image of the orm to be printed and vulcanizin~ the material after it fills the mold cavity. The mold is made usually by photoengraving techniques or other similar etching techniques and is constructed from such ma~erials as zinc, copper, or sometimes a special glass material. Layer 102 is made by placing the moldable plate ma~erial in contact with the mold and applying heat and pressure in a special press. The plate material softens~ fills the cavity o the mold and accepts the exact configuration of the mold~ The vulcanizing cycle is adjusted so that the plate~~aterial is maintained for a su-fficient time at a high enougll temperature to completely cure. As a result, the molded printing layer 102 has integral upraised printing lands 104 molded into its top or outer printin~ surace 105. The o~posite or inner surface 106 of layer 102 is relatively smooth.
The cushion layer 103 is prepared in the same manner, i.e., by vulcanizin~ an appropriate ~ubbery material in a mold but in this case one surface 107 of layer 103, which is intended to be inounted to the printing cylinder, is relatively smooth while the opposite surface 108 is discontinuous in the peripheral direction. The discontinuancies provide a plurality of spaced projections or pedestals 109 which are spaced sufficieTLtly from one .
~5{~
.
- another to prevent the setting up of compressive forces in the peripheral direction at the mounting surface.
Thus, a two-dimensional ~attern of spaced projections 109 integral with layer 103 and being of substantially the same height is provided to define a mounting surface.
The cross-section of projections 109 can ta~e any desired form such as circular 109a, ring-like lO9b, square 109c, or rectangular lO9d as shown in Figure 3.
The individual platforms 109 are usualIy spaced apart from each other by a distance which is preferably less than one-half of the thickness of plate 101 and the pattern of pedestals is usually, although not necessarily, uniform. The height of projections 109 is preferably about one-quarter to one-half the thic~ness o layer 103 or about one-eightll to one-quarter of the thickness of plate 101. The projections 109 should ~ccupy from 25 to 75% of the area corresponding to the area to be printed and preferably about 40 to 60% of that area.
In one preferred embodiment, projections 109 l~ere in the form of 144 pedestals of circular cross-sect:Lon per square inch and covered about 50~ of the surface area in a uniform pattern. As sho~n in the cut-a~ray portion of Figure 4~ projections 109 need not occupy the entire surface 108 of cushion layer 103 but only that area corresponding to the area o layer 102 ~hich carries printing lands 104.
Printing layer 102 and cushion layer 103 are joined by adhesively bonding mounting surface 108 of layer 103 to the inner support surface 106 of layer 102. It is necessary to adhere the t~-~o layers 102, 103 by means of a suitable adhesive 110 since it has been ,, .: ,. , found that attempts to vulcanize the mounting surface 108 of soft rubber layer 103 to the inner surface 106 of printing layer 102 has resulted in the destruction of the projections 109. Although any adhesive material which will bond mounting surface lQ8 to inner surface 106 can be used, it is preferred to use a material which is known in the trade as "Sticky Back".
Sticky back is a double-sided adhesive tape, about 0.005-0.020 inch thick and having a caliber variation of about 0.003-0.005 inch, and is substantially incompressible, i.e., it does not significantly yield when pressure is applied to the printing plate. It is commercially available, e.g., from the 3M Company as ScotchTM brand double-coated tape.
By constructing the instant plate as described above, cupping and other deformities of the printing when applied to such materials as thermo-formed or vacuum formed cups whose thickness is irregular can be substantially eliminated.
Accordingly, the printing plates of the present invention are particularly adapted for printing of such materials in such printing equipment as the process decorators described in U.S. Patent 3,645,201, copending application Serial No. 917,115, filed June 19, 1978, and the like. By virtue of the ins-tant construction, cushion layer 103 can be performed and stored or stockpiled for a substantial period of time before being adhered to printing layer 102. Additionally, because pedestals 109 are disposed substantially at the middle of plate 101 and layer 102 is harder than layer 103, deformities due to ex-pansion of printing lands 104 are substan-tially avoided.
~5~
- It will be appreciated that various changes and modifications can be made in the printing plate of the present invention without departing from the spirit and scope thereof. The various embodiments which have been described in this specification were intended to be illustrative only and not ~o be limitin~.
,
Additionally, the required use o~ the curved metallic backing layer 1 requires that *he metallic material be dedicated to this purpose.
Accordingly, it is the object of this invention to provide an improved printing plate which will produce a high fideli~y and sharpness in printing without haloing, cupping, unevenness, or other imperfections which can be produced without requiring a special partial cure subsequent cure procedure 9 or the use of a dedicated curved or 1at backing material or any special backing material. This and other objects of the invention will become apparent from the follo~ing detailed description in conjunction with the drawings of which Figure 1 is a cross-section ~f a printing plate of the prior art as heretofore described;
Figure 2 is a cross-section of a printing plate produced in accordance with the present invention;
Figure 3 is a plan vie~ of a section of the soft ~ushion layer of the instant printing plate; and Figure 4 is a plan view, partially cut away, of one embodiment of a printing plate in accordance with the present invention.
`"' `~:
5`~8~3 SU~I~IARY OF Tl-IE INVENTION
This invention relates to a compressible composite relief type printing plate and more particularly to relatively soft letter press type relief printing plates such as flexographic printing plates. The printing plate has a layer of a relatively hard rubbery material haviIlg an outer printing sur~ace and an inner support surface, a layer of a relatively so~t rubbery material having a surface which is discontinuous in the peripheral direction to provide a plurali~y of spaced projections integral wi~h the soft rubbery material and of substantially the same height to define a mountin~ surface, the mount;ng surface and the inner support surface being secured to-gether by an adhesive. The compressibility of the plate permits it to absorb excess pressures exerted against tlle ink ~ransfer image producing lands o-~ the printing plate so t}-at the integrity of the amount and size of images ~rans~erred to t}le surface being printed remains sub-stantially constant even though the thickness thereo~
may vary up to 0.008 inch in random patterns.
DESCRIPTION OF I'~-IE INVENTION
With reference to Figures 2, 3 and 4, the printing plate 101 has two layers 102, 103 o rubber-li~e material. Any oE the rubbery materials heretoore used ~or printing plates can be used to make layers 102 and 103. For e~ample, the rubber-like material can be natural rubber, butyl rubber, ethylene-propylene rubber, and the li~e, or harder materials such as the photo-~ polymers or "Dycril~ Such materials must be moldable and, in the case o~ the rubber and soft pla5tic com~ounds,capable of being vulcanized. As is conventional, the .
- s -rubbery material of prin~ing layer 10~ is harder relative to the rubbery material of cushion layer 103. For example, layer 102 can have a durometer rating of 50 to 90 while cushion layer 103 has a durometer rating of Z0 to 30.
Printing layer 102 is -formed by melting a suitable moldable relatively hard rubbery material in a mold which is the mirror image of the orm to be printed and vulcanizin~ the material after it fills the mold cavity. The mold is made usually by photoengraving techniques or other similar etching techniques and is constructed from such ma~erials as zinc, copper, or sometimes a special glass material. Layer 102 is made by placing the moldable plate ma~erial in contact with the mold and applying heat and pressure in a special press. The plate material softens~ fills the cavity o the mold and accepts the exact configuration of the mold~ The vulcanizing cycle is adjusted so that the plate~~aterial is maintained for a su-fficient time at a high enougll temperature to completely cure. As a result, the molded printing layer 102 has integral upraised printing lands 104 molded into its top or outer printin~ surace 105. The o~posite or inner surface 106 of layer 102 is relatively smooth.
The cushion layer 103 is prepared in the same manner, i.e., by vulcanizin~ an appropriate ~ubbery material in a mold but in this case one surface 107 of layer 103, which is intended to be inounted to the printing cylinder, is relatively smooth while the opposite surface 108 is discontinuous in the peripheral direction. The discontinuancies provide a plurality of spaced projections or pedestals 109 which are spaced sufficieTLtly from one .
~5{~
.
- another to prevent the setting up of compressive forces in the peripheral direction at the mounting surface.
Thus, a two-dimensional ~attern of spaced projections 109 integral with layer 103 and being of substantially the same height is provided to define a mounting surface.
The cross-section of projections 109 can ta~e any desired form such as circular 109a, ring-like lO9b, square 109c, or rectangular lO9d as shown in Figure 3.
The individual platforms 109 are usualIy spaced apart from each other by a distance which is preferably less than one-half of the thickness of plate 101 and the pattern of pedestals is usually, although not necessarily, uniform. The height of projections 109 is preferably about one-quarter to one-half the thic~ness o layer 103 or about one-eightll to one-quarter of the thickness of plate 101. The projections 109 should ~ccupy from 25 to 75% of the area corresponding to the area to be printed and preferably about 40 to 60% of that area.
In one preferred embodiment, projections 109 l~ere in the form of 144 pedestals of circular cross-sect:Lon per square inch and covered about 50~ of the surface area in a uniform pattern. As sho~n in the cut-a~ray portion of Figure 4~ projections 109 need not occupy the entire surface 108 of cushion layer 103 but only that area corresponding to the area o layer 102 ~hich carries printing lands 104.
Printing layer 102 and cushion layer 103 are joined by adhesively bonding mounting surface 108 of layer 103 to the inner support surface 106 of layer 102. It is necessary to adhere the t~-~o layers 102, 103 by means of a suitable adhesive 110 since it has been ,, .: ,. , found that attempts to vulcanize the mounting surface 108 of soft rubber layer 103 to the inner surface 106 of printing layer 102 has resulted in the destruction of the projections 109. Although any adhesive material which will bond mounting surface lQ8 to inner surface 106 can be used, it is preferred to use a material which is known in the trade as "Sticky Back".
Sticky back is a double-sided adhesive tape, about 0.005-0.020 inch thick and having a caliber variation of about 0.003-0.005 inch, and is substantially incompressible, i.e., it does not significantly yield when pressure is applied to the printing plate. It is commercially available, e.g., from the 3M Company as ScotchTM brand double-coated tape.
By constructing the instant plate as described above, cupping and other deformities of the printing when applied to such materials as thermo-formed or vacuum formed cups whose thickness is irregular can be substantially eliminated.
Accordingly, the printing plates of the present invention are particularly adapted for printing of such materials in such printing equipment as the process decorators described in U.S. Patent 3,645,201, copending application Serial No. 917,115, filed June 19, 1978, and the like. By virtue of the ins-tant construction, cushion layer 103 can be performed and stored or stockpiled for a substantial period of time before being adhered to printing layer 102. Additionally, because pedestals 109 are disposed substantially at the middle of plate 101 and layer 102 is harder than layer 103, deformities due to ex-pansion of printing lands 104 are substan-tially avoided.
~5~
- It will be appreciated that various changes and modifications can be made in the printing plate of the present invention without departing from the spirit and scope thereof. The various embodiments which have been described in this specification were intended to be illustrative only and not ~o be limitin~.
,
Claims (3)
1. A uniformly thick composite printing plate comprising a layer of a relatively hard rubbery material having an outer printing surface and a relatively smooth inner support surface, a layer of relatively soft rubbery material having a surface which is discontinuous in the peripheral direction and defined by a plurality of spaced pedestal projections integral with the soft rubbery material and of substantially the same height to define a mounting surface, and an adhesive securing said mounting surface to said inner support surface; said adhesive comprising a sub-stantially incompressible double-sided adhesive tape; said plurality of spaced pedestal projections occupying about 25%
to 75% of the surface of said discontinuous surface corres-ponding to the area of said outer printing surface which is image-carrying.
to 75% of the surface of said discontinuous surface corres-ponding to the area of said outer printing surface which is image-carrying.
2. The composite printing plate of claim 1, wherein said spaced pedestal projections are uniformly spaced and are of annular cross-section.
3. The composite printing plate of claim 1) wherein said projections occupy 40 to 60% of said area.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US2206379A | 1979-03-19 | 1979-03-19 | |
| US022,063 | 1979-03-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1125089A true CA1125089A (en) | 1982-06-08 |
Family
ID=21807631
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA347,426A Expired CA1125089A (en) | 1979-03-19 | 1980-03-11 | Compressible composite flexographic plate |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5625495A (en) |
| AU (1) | AU5653180A (en) |
| CA (1) | CA1125089A (en) |
| DE (1) | DE3007703A1 (en) |
| ES (1) | ES8202289A1 (en) |
| GB (1) | GB2044176A (en) |
| IT (1) | IT1130024B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6894000B2 (en) | 2002-04-26 | 2005-05-17 | Kodak Polychrome Graphics Llc | Method for preparing imaged members and imaged members prepared thereby |
-
1980
- 1980-02-29 DE DE19803007703 patent/DE3007703A1/en active Pending
- 1980-03-05 GB GB8007525A patent/GB2044176A/en not_active Withdrawn
- 1980-03-11 CA CA347,426A patent/CA1125089A/en not_active Expired
- 1980-03-13 IT IT8020580A patent/IT1130024B/en active
- 1980-03-18 ES ES489697A patent/ES8202289A1/en not_active Expired
- 1980-03-18 AU AU56531/80A patent/AU5653180A/en not_active Abandoned
- 1980-03-19 JP JP3570180A patent/JPS5625495A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| IT1130024B (en) | 1986-06-11 |
| ES489697A0 (en) | 1980-11-01 |
| DE3007703A1 (en) | 1980-10-02 |
| ES8202289A1 (en) | 1980-11-01 |
| GB2044176A (en) | 1980-10-15 |
| IT8020580A0 (en) | 1980-03-13 |
| AU5653180A (en) | 1980-09-25 |
| JPS5625495A (en) | 1981-03-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |