FR2729100A1 - PRINTING BLANKETS FOR METAL EFFECT INK - Google Patents

Abstract

The present invention relates to a method for increasing the number of articles capable of being printed using ink comprising platelet type pigments. This process consists in using a printing blanket having a base, an elastomeric layer and a surface film, this surface film being formed from a polymeric thermoplastic material which has a low affinity with respect to the pigments of the platelet type contained. in the ink, by applying said ink to said blanket and by transferring said ink from the blanket to the printing medium while reducing the rate of formation of ink clumps and paper fibers on the blanket , this process therefore making it possible to increase the duration of use of the blanket before it requires cleaning.

Description

PRINTING BLANKETS FOR INK

METALLIC EFFECT

FIELD OF THE INVENTION

  The object of the present invention is a pig transfer printing system.

  platelet type elements on a printing member and relates to the process

use of this system.

BACKGROUND OF THE INVENTION

  Printing machines used for offset printing, water-free offset printing, cold curable-hot curable metallic decoration and other types of printing used in the graphic arts, include

  general a plurality of cylinders intended to perform various functions. In particular

  bind, most of the cylinders are intended to come into direct contact with the printing supports, papers or other surfaces, intended to be printed, either to transfer the ink on this surface (impression cylinder), or to realize d '' other functions including paper movement functions, feeding functions (transfer cylinders) or pressure exertion functions (

  pressure) against the printing cylinders.

  Although the aforementioned cylinders perform various functions, they can all be

  coated with the same type of blanket to be provided with dy-

  similar mechanical and mechanical (e.g. deformability and speed

  peripheral retention) to all pairs of cylinders, so as to ensure accuracy

  the highest possible print and paper handling capacity.

  A large number of embodiments of blankets are described in the state of the art. For example, patent No. US-2-792-321 in the name of Fredericks describes an elastic printing blanket comprising a smooth upper surface,

  hard, moisture-proof and capable of being easily cleaned.

  US-3-881-045 describes an offset printing blanket comprising a layer

  void-free printing, a layer of polyester film, a layer of

  highly elastic wearing and a fibrous support layer which does not give rise to

  compression when used for the intended purpose.

  Patent No. US-4-015-046 in the name of Pinkston describes a printing blanket

  comprising a base, a fluorocarbon surface layer and a polychlorinated binder

  oak which can be used with a wide variety of inks and cleaning solutions

  toyage. R 13400 \ 13439 DOC - 9janvler 1996- 1/12 Patent n JP 56-144196 describes a printing blanket comprising a base

  rubbery and a lipophilic surface, which results in a uniform ink transfer

  shape and constant from a printing plate.

  Patent No. US4-471-011 in the name of SpôOring describes a multi-pressure blanket

  layers comprising a reinforced section composed of layers of fabric between which rubberized layers are provided, a coating and a coating

  rubberized, which blanket has improved durability and resistance.

  DE 2-227-485 describes a duplication or offset printing machine comprising

  an offset cylinder having a cylindrical surface formed of a polymer present

  both a low critical surface tension and a pressure cylinder intended to co-

  operate with this surface. This document does not deal in any way with the problem of paper handling and printing accuracy associated with productivity requirements. FR-2-061-062 describes a coating of a polyamide film for cylinders of

  pressures intended for use in a printing system.

  DE 2-718-224 describes a process for preparing a printing blanket in the-

  which a fluororesin is used as an outer layer. No reference has

  however relates to the above problems.

  JP 57-117-999 describes an offset printing blanket which includes a laminate formed by an elastomer layer with an elastomer surface of PVC or PVDC and a plasticizer of

  polyester type with a molecular weight of 1,450 to 6,000. The blanket pre-

  feels the necessary rubbery elasticity, soft touch, ink / ink transfer and required chemical resistance properties, and can be easily washed. PCT application WO91 / 11330 describes a blanket which does not exercise a printing function, which includes a base, an elastomeric layer and a surface film disposed on the elastomeric layer. The film has a low affinity for printing inks and is formed from PVC, polyester, polyethylene, PTFE or PVF. In operation, the blanket can allow the handling of printed materials and only give rise to a much weaker formation on the blanket.

  clumps of ink particles or fibrous masses from the paper.

  From the above, it can be seen that none of the blankets described have been used for printing inks which contain platelet type pigments. When conventional printing blankets are used for printing inks that

  contain platelet type pigments their performance is not satisfactory.

  Specifically, these printing blankets, due to the formation of clusters of

  paper and ink fibers used require after a relatively long printing time

  tively weak, washing for the elimination of all these clumps. This imperative

  R '13400 \ 13439 DOC - 9 Jan Ir 1996-212 pleads the loss of time, energy and manpower. Thus there remains a need for a printing blanket which can be used for printing applications making use of inks containing platelet type pigments and which avoids or minimizes the problems of formation of clumps of ink on the blanket, which therefore extends the total life of the blanket.

SUMMARY OF THE INVENTION

  The subject of the present invention is a method for increasing the number of articles capable of being printed using inks containing platelet-type pigments, which consists in using a printing blanket having a base, an elastomer layer and a surface film, this surface film being formed of a polymeric thermoplastic material which has a low affinity for platelet type pigments and to transfer the ink from the blanket to the printing medium while reducing the rate of formation ink clogging on the blanket and therefore increasing the duration of use of the blanket before it is necessary to clean it. Specifically, the printed article may be paper and at least 8,000 up to 15,000 or 20,000 or more sheets can be printed without requiring interruption of printing to proceed.

cleaning the blanket.

  In this process, the ink is preferably applied to the blanket, by an offset printing process, before the ink is transferred to the article. The stage

  blanket formation may include the formation of a pre-printed blanket

  sensing a surface film formed of polymeric thermoplastic material in which the printing blanket is formed by bonding the surface film to the blanket. The surface film can be bonded to the blanket by an adhesive or by a rolling process.

  cold before the blanket vulcanization step.

  The wafer-type pigment contained in the ink generally comprises a flat inorganic material, such as a mica coated with one or more layers of metal oxides. The metal oxide layers can be formed from transition metal oxides or some of their mixtures. Likewise, the elastomeric layer of the printing blanket will preferably comprise a compressible layer having a microporous structure formed from a plurality of closed or open cells. The base will include a plurality of layers between which are interposed layers, one of which is said compressible layer. Advantageously, the surface film is formed from polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate,

  polyethylene, polyvinyl fluoride, polyvinylidene fluoride or tetra-

  fluoropolyethylene. Preferably, the surface film is formed from a poly-

  mother which contains a fluoride or a constituent of a fluoride or a fluoropolymer.

  R '13400 \ 13439 DOC 9 alnvwr 1996 - 3112

BRIEF DESCRIPTION OF THE DRAWINGS

  Other objects and objects of the present invention will appear on reading the

  present description and drawings given by way of nonlimiting examples of a mode

  preferred embodiment of the present invention.

  Figure 1 is a section of a preferred embodiment of a blanket

offset printing.

DETAILED DESCRIPTION OF THE INVENTION

  According to the present invention, improved performance can be achieved.

  naked in the transfer of inks containing platelet-type pigments from a

  printing blanket to a printing medium such as paper, cardboard, metal

  tal or other media commonly used in printing techniques.

  The ink is transferred using a printing system which includes a plurality of cylinders having various functions in the handling of printed media, both

  before after printing the item.

  According to a specific preferred embodiment of the present invention, the

  printing blankets are attached to the cylinders of the printing system. These cy-

  cylinders include, without this being a limitation, the cylinders

  that transfer the ink to the print media and the press cylinders

  which interact on one or more printing cylinders so as to exert a printing pressure on the printing medium brought between the cylinders

  printing and pressure cylinders.

  Printing cylinders generally include a base which includes a compressible layer having a microporous open cell structure or

  closed and an elastomeric layer or sublayer. These characteristics are generally

  are well known to those skilled in the art and are fully described in the patent

  US-5,364,683 and published PCT application PCT / US92 / 02973, the content of which is incorporated

  referenced herein for further details relating to the construction of the blanket. The use of high melting point thermoplastic microspheres described in the PCT patent application is particularly preferred.

  for the formation of the compressible layer.

  To the elastomer layer can adhere a surface film which has a low

  affinity for the platelet type pigments of the ink. By "low affinity", we mean

  tends that the surface film of the printing blanket will ensure a high release of the platelet-type pigments so that the printing blanket can be used for printing 15,000 to 20,000 articles before washing. The film has no effect on the elasticity or pliability characteristics of the printing blanket characteristics which all depend on the nature of the elastomer layer and the base. In addition, the film drastically reduces the adhesion of R \ 13400M3439 DOC - 9 Janvi 1996 -4/12 pigment and particles of the printing medium, such as paper fibers and

  fabric dust, blanket printing so that the handling of the sup-

  printing port and printing accuracy are preserved. In addition, because the film deters adhesion of debris, the printing blankets require less cleaning per unit time of operation of the printing system and per-

  put to keep high productivity.

  The film may be formed from a polymeric material including, without being in any way a limitation, polyvinyl chloride, chloride of

  polyvinylidenes; polyesters, such as polyethylene terephthalate and poly-

  butylene terephthalate; polyethylene; fluoropolymers, such as polyvinyl fluoride, polyvinylidene fluoride and polytetrafluoroethylene, as well as their mixtures, since these polymers have a low affinity for a mica coated with a metal oxide. Preferably used is a fluorine-containing polymer, such as polyvinyl fluoride, which leads to the best results. A commercially available polyvinyl fluoride polymer is TEDLAR manufactured by

  DUPONT. The film has a thickness of between 10 and 100 µm and preferably

between 30 and 50 days.

  The film can be bonded to the elastomer layer by a cold rolling process prior to the treatment of the elastomer layer by vulcanization. Thanks to the use of this latter method, excellent adhesion of the film to the underlying elastomer layer is obtained. Alternatively, the film may be point independent

  structure of the assembly formed by the base and the elastomer layer, and being sim-

  fully combined with the assembly during the preparation and assembly stage of the pressure cylinder. In this case, the film can be attached to the elastomer layer at

  using a layer of adhesive which is placed in between.

  When a separate film layer is to be vulcanized on the carcass, it is preferable to use a multilayer structure which includes a rubber layer and the film. Compared to the rubber layers which are conventionally used, the thickness of the rubber layer of the laminate is reduced so as to allow the inclusion of the film while maintaining a thickness similar to that of the

classic layers.

  Preferably, the coating of the printing blankets of each printing cylinder comprises a base and an elastomeric layer, and the coating of the printing blankets of each pressure cylinder further comprises a

surface film layer.

  The pigments used in the printing method of the present invention

  are platelet type pigments. Such platelet type pigments include

  advantageously have a non-pigmentary core formed of an inorganic material.

R '13400 \ 13439DOC-9 year,' 1996-5 / 12

  flat or folicular. The flat core is coated with one or more metal oxides.

  liques. Typically transition metal oxides are used.

  The non-pigmented cores act as a support for the metal oxide layer (s) which lead to a glossy effect on the printing medium to which the pigment has been applied. The non-pigmentary nuclei which can be used for such use include, without this being a limitation, mica, talc, kaolinite and other phyllosilicates. Preferably, the non-pigmentary core is mica, and the metal oxide layers include titanium dioxide, iron oxide and their mixtures. The diameter of these platelet-type pigments is understood

  between I and 500 pim, preferably 5 and 200 grm. A series of flat-type pigments

  commercially available quettes is sold under the name of IRIODIN by MERCK. These pigments which are sold in series 100, 200, 300 and 500, are capable of imparting a silver, golden or metallic luster effect as well as

interference effects.

  Alternatively, pigments containing a non-metallic or organic ion may

  can be used in the printing method of the present invention. These pigs

  are known to those skilled in the art, specialist in the printing field, and are preferably dispersed in a vehicle such as clay, celluloses such as starch

and the like.

  The pigments are dispersed in a suitable vehicle in order to allow an ink type product to be obtained which is transferred to the paper from the support.

  according to conventional offset printing processes.

  Figure 1 shows in section the blanket of the present invention. The printing base or carcass is indicated by the reference 2 and the elastomer layer by the

  reference 3. The base 2 is formed of a plurality of layers including a layer

  4, two intermediate layers 5 and a compressible layer 6 which includes a microporous structure with open or closed cells. Microspheres

  high melting point thermoplastics consisting of EXPANCEL 091 are preferred

  rees for this layer. Then above the compressible layer is arranged a

another layer of fabric 7.

  The upper elastomer layer 3 is generally formed of a rubber

  nitrile only or combinations of layers of nitrile rubber and poly-

  sulfide or other rubbery materials. In the construction shown, a layer of nitrile rubber 8 is in contact with the carcass and supports the surface film 10, which is applied to the elastomer layer 4 and is preferably

  formed from polyvinyl fluoride (PVF).

  To allow optimum adhesion to be obtained, a layer 9 of a material

  an adhesive thermoplastic layer is placed between the elastomer layer 3 and the film R. 13400 \ 1343) DOC -) January 196 - 6/112 surface 10 in order to ensure sufficient bonding. A commercially available material preferably used is chlorosulfonated polyethylene, as sold under

  the trade name of Hypalon by DUPONT. Other thermo-materials

  halogenated plastics can also be used. When included, the total thickness of layers 8, 9, and 10 is advantageously kept at the same thickness

  that of the upper elastomer layer of a conventional blanket.

  To form the blanket 1, use is made in the initial step of a process

  classic in which the base 2 and the elastomeric layer 3 which are above it are formed

  perposed. This method includes sequential steps of coating the layers with elastomeric materials and coupling other layers using a

cold rolling.

  Before subjecting the base 2 and the elastomer layer 3 to the vulcanization step

  tion in order to stabilize the elastomer layer 3, the film 10 is cold rolled. Then the pre-vulcanized or green blanket 1 is subjected to vulcanization, which allows in one step the stabilization of the elastomer layer 3 and the anchoring of the film 10 on this layer. This vulcanization consists in heating the green blanket 1 to a temperature between 120 C and 160 C, preferably between 135 C and 150 C, under pressure

  from 130 to 190 psi, preferably between 145 to 175 psi.

  The blanket 1 thus obtained has an outer surface which has an

  extremely low with regard to ink formed from platelet type pigments and can be easily washed preferably with an aqueous solution of detergents. In addition, the film 10 provides excellent resistance to surface abrasion, as well as excellent chemical resistance to the action of the solvents generally used.

in printing systems.

EXAMPLE

  The performance of a blanket according to the present invention comprises a base

  or carcass formed of a lower layer, two layers of fabric, a composite layer

  pressure of closed cells, another layer of tissue, and a layer of elastomer

  The outer layer formed from the combination of a layer of nitrile rubber and a layer of hypalon, and an outer layer of polyvinyl fluoride is compared to that of a conventional blanket of the same construction but not including the outer layer of polyvinyl fluoride. The blankets are placed on the printing cylinder of a printing system and are used for offset printing of paper using IRIODIN ink. After printing only 4,000 to 5,000 copies, the conventional blanket requires washing to remove any lumps of ink and significant paper fibers that may affect the quality of printing on paper. In comparison, the blanket of the present invention is capable of printing 15,000 to 20,000 copies before the quality of printing is affected. Likewise, due to the low affinity of the ink to the blanket, the heap of ink and paper fibers is easily removed by washing.

  which allows rapid reuse of the blanket.

  The present invention is not limited to the embodiments described and

  presented; it is susceptible of numerous variants accessible to those skilled in the art

  without departing from the spirit of the invention.

  R 113400 \ 13439 DOC - 9jalv, 1996 - / 12

Claims (22)

  1.- A process to increase the number of articles likely to be printed   més using ink comprising pigments of type platelets, which process   consists in using a printing blanket having a base, an elastic layer   surface and a surface film, this surface film being formed of a polymeric thermoplastic material which has a low affinity with respect to the pigments of the platelet type contained in the ink, in the application of said ink to said blanket and in transferring said ink from the blanket to the printing medium while reducing the rate of formation of ink clumps and paper fibers on the blanket, this process therefore making it possible to increase the duration of use of the blanket before that he does require cleaning.   2. The method according to claim 1, in which the first step includes the formation of a printing blanket having a surface film formed of a   polymer thermoplastic material.   3. The method according to claim 2, in which the printing blanket   is formed by bonding the surface film to a conventional blanket.   4. The method according to claim 3, in which the surface film is bonded. to the blanket with an adhesive.   5. The method according to claim 3, in which the surface film is bonded. blanket by cold rolling.   6. The method according to claim 5, in which the film is applied to the   elastomer layer prior to the vulcanization step.   7. The method according to claim 3, in which a layer of material   halogenated thermoplastic is interposed between the blanket and the outer film.   8. The method according to claim 1, in which the pigment of the plat type   bowls in the ink are formed from an inorganic, film-like material   or flat, coated with one or more metal oxides, the ink being applied to the white   chet by an offset printing process.   9. The method according to claim 8, further comprising the choice of the inorganic pigment from a group comprising mica, talc, kaolinite and other phyllosilicates and the choice of metal oxide layers from the group of   transition metal oxides or mixtures thereof.   10. The method according to claim 9, wherein the inorganic pigment is mica.   11. The method according to claim 1, wherein the elastomeric layer of the   said printing blanket is formed by a compressible layer having a   microporous structure and comprising a plurality of open or closed cells.   R 13400 \ 13439DOC -qjan ,, s1er19q6-912 12.- The method according to claim 1, which further comprises the choice of the material from which the surface film is formed from materials consisting of polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate , polybutylene terephthalate, polyethylene, polyvinyl fluoride, polyvinylidene fluoride or polytetrafluoroethylene. 13. The method according to claim 1, which further comprises the choice of the material from which the surface film is formed, from the polymeric materials which   contain a fluoride, a fluoride component, or a fluoropolymer.   14.- The method according to claim 1, wherein said base comprises a plurality of layers between which are interposed layers, one of which is said compressible layer.   15.- The method according to claim 1, in which the print medium is   paper and in which at least 8,000 sheets can be printed without the need site cleaning the blanket.   16.- Printing blanket having a base, an elastomeric layer and a surface film, this surface film being formed of a thermoplastic material   polymer which has a low affinity for platelet type pigments.   17. A blanket according to claim 16, in which the surface film is bonded to   the elastomer layer with an adhesive.   18. A blanket according to claim 16, in which the surface film is bonded to   the elastomer layer by cold rolling.   19. A blanket according to claim 18, in which the film is applied to the   elastomer layer prior to the vulcanization step.   20. A blanket according to claim 18, in which a layer of material   halogenated thermoplastic is placed between the blanket and the surface film.   21. A blanket according to any one of claims 16 to 20, in which the   elastomeric layer is formed by a compressible layer having a structure   microporous and comprising a plurality of open or closed cells.   22. A blanket according to any one of claims 16 to 21, in which the   material from which the surface film is formed is chosen from the group comprising   polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, poly-   butylene terephthalate, polyethylene, polyvinyl fluoride, polyvinyl fluoride   dene or polytetrafluoroethylene.   23. A blanket according to any one of claims 16 to 22, in which the   material from which the surface film is formed is chosen from polymer materials   which contain fluoride, a fluoride component, or a fluoropolymer.   R H3400 \ 13439 DOC - q nw t 199 - 10/12 Il   24.- The method according to any one of claims 16 to 23, wherein   said base comprises a plurality of layers between which are interposed   layers, one of which is said compressible layer.   R '13400 \ 134l) DOC - 9 [anv.er 19% - I / 1 2