FR2635725A1 - PRINTING ELEMENT AND PRINTING METHOD FOR COPYING MICROSTRUCTURES - Google Patents

Abstract

a) Printing element and printing method for copying microstructures. b) Element characterized in that the copy layer 2 is a sheet of large surface resulting from a dried solution formed of cellulose triacetate distributed homogeneously over a thickness of between 1 and 15 mum and integrally connected to a support element 3 below. c) The invention relates to a printing element and printing method for copying microstructures.

Description

"Printing element and printing method for

copy microstructures ".

  The present invention relates to a printing element for copying microstructures, composed of a layer of copying covered with a layer

increasing the optical contrast.

  The invention also relates to a method

  for producing such printing elements.

  According to the publication "Metallographische und fraktographische Untersuchung an Bauteilen", VGB Kraftwerkstechnik 62, Book No. 6, June 1982, pages 519 to 524, polyvinyl acetate solutions with chlorinated hydrocarbons are known which are applied as sheets in solution on surface elements with microstructures; these applications are reinforced by a cast resin; the use of chlorinated hydrocarbons is a disadvantage because it is a nuisance for the environment and for health. Gold,

  this sheet in solution makes it possible to reach

  lutions up to 1 pm. According to the same publica-

  Sandwich printing elements formed from a sheet forming a copy layer of a reflective aluminum layer and serving as a lower support, as well as a film of glue for direct application to a substrate, are known. object support. According to this same publication, it is possible to use such sheets having a thickness of the order of 100 μm and

  ridge lengths of a few centimeters.

  Such prints of sheets which are also known according to DIN 54150, section 3.2, have the disadvantage that large area prints corresponding to several square centimeters have important defects such as

  air inclusions and inflated parts.

  The only process that does not create air inclusions is the one-coat varnish according to DIN 54150 section 3.1 on nitrocellulose or a synthetic resin base. Unlike printing sheets, you can not remove such prints of varnish, without leaving traces on large areas to copy so that

  has the disadvantage of faulty areas and structures

  its, important in the copy layer. In addition, you can not remove or manipulate large-area prints in the form

  of one-coat varnish prints.

  In addition to printing by sheet or varnish for microstructures, casting processes are also known. These methods certainly make it possible to produce mechanically stable printing elements which are not free of air inclusion and have the disadvantage of a microscopic, clean structure which complicates the operation.

  microscopic. Copies of large curved surfaces

  dimensions have the disadvantage of not giving a planar preparation for microscopic operation. The object of the present invention is to create a printing element for copying microstructures, having a layer of copying covered with a layer

  increasing the optical contrast, which is mechanical-

  stably stable for copying large surfaces with microstructures

  data carriers from large areas to micro-

  structures and parts of large surfaces, mechanically stressed and having microcracks, for copying them without bubbles and without bulging parts and which can be removed without leaving any remainder of the surface to be copied; the invention also proposes to create a method of manufacturing such printing elements, in particular avoiding the use of troublesome solvents

  for the environment and for health, such as

chlorinated hydrocarbons.

  This problem is solved by the invention thanks to a printing element characterized in that the

  copying layer is a sheet of large surface area

  sulting from a dried solution of triacetate

  cellulose homogeneously distributed over a thick

  between 1 and 15 pm and connected in solidarity

  to a support element underneath.

  The printing element according to the invention overcomes the disadvantages of the prior art. The invention makes it possible to obtain at the same time good characteristics of copy, resolution and

  of printing a sheet while avoiding the inclusion of

  air and the convex parts of the printing varnish

  when preparing a sheet material according to the process characterized in that a) a sheet material is swollen in a solvent, b) a solution sheet is formed by homogenizing

  the material of the leaf by a freezing step

  (c) applying the sheet in solution to the copying surface having the microstructure, d) drying the sheet in solution to form

  a copy layer on the copying surface,

  sensing the microstructure, e) forming a printing blank by reinforcing the copy layer on the copying surface by applying a backing member, f) removing the printing blank from the surface having the microstructure, g ) forming a printing member by applying an optical layer to the microstructure of the printing blank; this sheet in solution must be applied with a thickness of between i and 15 pm to the surface of the microstructures to be copied to dry and give a

copy layer.

  A leaf in solution, particularly advantageous, is composed of cellulose triacetate which is distributed homogeneously in acetone constituting the solvent and allows to arrive at a

  resolution power less than 0.5 μm.

  The surface of the copying layer is coated with an optical contrast enhancing layer having a thickness of between 0.01 and 0.3 μm in chromium, palladium, aluminum, gold, tantalum, platinum, nickel, tungsten, hydrocarbon or alloys of these bodies or of several layers of these bodies. The copy layer, thin, without air inclusion and without curved part,

  form with the support element, a draft of

  reinforced, self-supporting. The support element

  form of plate, disc or cylinder, is advantageous

  in a thermosetting material such as

  an epoxy resin or a thermoset plastic

  curable reinforced with textile fibers of

glass or carbon.

  According to a particular embodiment

  Advantageously, the support element is in the form of a resilient layer and comprises a support varnish further applied against the underside of the copying layer. This varnish can be a varnish

print, known.

  This embodiment of the support element is particularly suitable for making impressions of

  inner surfaces of hollow bodies, spherical in shape

that, conical or cylindrical.

  For micro-analyzes of a flat surface,

  conical or cylindrical, reinforces the outline of the

  elastic preinte formed of the sheet in solution,

  dried and the support varnish by a strip of

  Synthetic re with double-sided adhesive or sticky faces which is connected to a flat support plate

  giving a support element to several layers.

  The thickness of the support element with one or more layers is advantageously

0.06 mm and 10 mm.

  The invention also relates to a method

  to produce a printing element according to the invention

  This process is characterized by the steps of: a) swelling a sheet material in a solvent, b) forming a solution sheet by homogenizing

  the material of the leaf by a freezing step

  (c) applying the sheet in solution to the copying surface having the microstructure, d) drying the sheet in solution to form a copying layer on the copying surface, having the microstructure, e) forming a blank printing by reinforcing the copying layer on the copying surface by applying a support element, f) removing the printing blank from the surface having the microstructure, g) forming a printing element by application. of an optical layer on the microstructure of

the printing blank.

  This method makes it possible to advantageously

  one or any number of fingerprints having

  reproducible quality of microstructured surfaces

  They can be copied without distorting the microstructure of the surface with varnish residues. It is particularly difficult to make an impression element using a copying layer formed from a sheet material which corresponds to the total homogeneous dissolution of this compact material.

  in a solvent containing no chlorinated hydrocarbon

  re. It is certainly known to dissolve the cellulose triacetate constituting the material of the sheet,

  surface with acetone and inflate this tria

  CETATE. However, even after the usual stages of boiling point of the solvent, the solution is not homogeneous, has residues and is useless

as a sheet in solution.

  Only by cooling through

  freezing of the solution that has been successfully

  surprising to form a sheet in solution, homogeneous. To prepare the freezing step, we put

  the material of the sheet in a solvent at temperatures of

  eratures between room temperature and

  boiling point of sclvant to swell.

  In the preferred combination of acetone

  and cellulose triacetate have been found

  temperatures between 280 * K and 320'K.

  The cellulose triacetate is allowed to swell at such temperatures for the periods between

0.5 and 3 hours.

  For this, a mixture of 20 to 200 liters of solvent per kg of material of the sheet is used. Preferably, it is also possible to produce the sheet concentrates in solution with 10 liters of

  solvent for 1 kg of sheet material.

  After swelling, the mixture is cooled to temperatures below the freezing point

  solvent. For the preferential combination of

  tone and cellulose triacetate are used

  temperatures between 75 * K and * K. Then, while stirring the solution, it is warmed to room temperature to form a sheet in solution comprising the material of the distributed sheet.

  homogeneously in the solvent.

  When making a concentrate of the sheet

  in solution through the freezing step, dilute this concentrate before using it as

sheet in solution.

  The sheet in solution can be applied

  on the copying surface, presenting microstructures

  without air inclusion, by applying

  paint, spray or

  jection and giving after drying a layer of copy

  having a thickness of between 1 and 15 pmn.

  In the case of the preferential combination of acetone and cellulose triacetate, it is dried at temperatures between 280'K and 325'K and this drying is done according to the thickness of the layer of

copy for 1 to 30 seconds.

  After drying and before removing the diaper

  of copy, the copy layer is reinforced by a

  such as a reinforcing varnish or a thermosetting material with or without

  reinforcement to form a draft impression.

  The shape and choice of materials for

  the support element depend on the surface to be copied.

  In the case of data carrier surfaces having microstructures, it is possible to produce plate, disk or cylinder-shaped bearing elements. In this case, the shape is stabilized and

  gets rigidity by thermally plastic materials

  hardenable with or without fiber reinforcement.

  In the case of a room defect analysis

  requested, having a complicated surface

  for example flat, conical or cylindrical, it is desirable to have an elastic impression blank,

  in the form of a layer, which is produced by spraying

  spatula application or projection of an additional reinforcing varnish on the copying layer and after removal of the surface is fixed this blank by a strip of synthetic material adhesive or adhesive on both sides, on a

flat support plate.

  The support element is put in place on the

  copy layer by brushing, spraying

  application, spatula application, rolling, casting,

pressing or injection.

  The impression blank is converted into an impression element according to the invention by, for example, spraying, vacuum vaporising or chemical deposition of an optical contrast-increasing layer and having a thickness of between 0.01 and 0.3 μm. The thickness of the layer and the material constituting it depend on the optical requirements of the optical detection system of the microstructured surface that is copied, such as for example a

  laser scanning device, an electron microscope

  frame or a light microscope. As

  example, the table given in the description states

  some materials suitable for the optical layer and

  the method of application of these materials.

  Transparent organic or inorganic layers such as, for example, silicon dioxide, indium oxide, tantalum oxide,

  acrylic glass can for example be

  the impression element for example by immersion, spraying, vapor deposition, sputtering or deposition

  durable or temporary protection.

  The method according to the invention also allows

  a two-sided copying layer

  crostructures on support elements in the form of

  discs or plates. For this, we equip two surfaces

  these microstructures with a copy layer according to the invention and are secured to a common support element.

  The present invention will be described in a manner

  re more detailed with the aid of an example of embodiment shown schematically in the accompanying drawings in which:

  FIG. 1 comprises a printing element

  sion of negative microstructures.

  FIG. 2 shows a printing element having a copying layer on both sides, with

  faces with positive microstructures (in

  lief) and - Figure 3 shows a printing element

  complex microstructures.

  Figure 1 shows a schematic section of a printing element provided with an optical layer 1, a copy layer 2 and a support 3 for example -in epoxy resin. For this, a layer of a homogeneously distributed cellulose acetone and acetone solution was sprayed onto a negative microstructure surface resulting, for example, from microcracks and etching. After the solution sheet has been dried to form a copying layer 2, an epoxy resin constituting the support 3 is cast. After removal of the printing preform 8, consisting of a copy layer 2 and the support 3, vaporizes

  gold on the surface of the printing blank 8.

  Fig. 2 shows a schematic sectional view of a printing element having a copying layer 2 on both sides as is advantageous for the serial production of microstructure data carriers. For this, two disk-shaped plates are coated with positive microstructures (in relief) to form a solution sheet on their surface and after drying, a plate of synthetic material reinforced with

  fibers but whose surface is not yet hardened.

  After removing the disk-shaped plates having the microstructures, the printing blank is allowed to harden and then provided on both sides with a layer 1 providing the optical contrast, aluminum; then we protect the printing element in

  disk shape with a layer of acrylic glass

  what constitutes the transparent layer 4 provided on

  both sides, proceeding by immersion.

  Figure 3 is a schematic sectional view of a printing element with complex microstructures such as those existing on the surface of complicated shapes of highly stressed parts. The copying layer 2 was reinforced in this case by a layer of reinforcing varnish 5, elastic and raised with a strip of synthetic material 6 sticking on both sides of the outer surface with complex microstructures and glued on a plate of

  support 7, plane. The reinforcement varnish 5, the ban-

  of synthetic material 6 tacky on both its

  these and the support plate 7 form here a carrier 3 with several layers. On the printing blank formed of the copy layer 2 and the support 3 is sprayed

  a very high contrast optical layer 1, made of nickel.

TABLE i:

  Materials and method of application for obtaining a

  contrast-enhanced optical layer having a thick

between 0.01 and 0.3 pm.

  Material Application Process Spray Vaporization

W + +

  Ai + + Ni + Au + Au-Pd + Ta + Pt + Cr + C- + + = suitable or appropriate application method

very well.

  - = method of application that is not suitable or which

is less suitable.

Claims (4)

R E V E N D I C A T I ONS   1-) Printing element for copying microstructures, composed of a copy layer   covered with a layer that increases the contrast   characterized in that the copying layer (2) is a large-area sheet resulting from a dried solution of cellulose triacetate homogeneously distributed over a thickness of between 1 and 15 μm and integrally connected to an element   support (3) below.   2 ') Printing element according to the claim   1, characterized in that the optical layer (1) has   a thickness of between 0.01 and 0.3 μm.   3 *) Printing element according to one   shell of claims 1 and 2, characterized in that   that the solution sheet is acetone with   cellulose triacetate homogeneously distributed.   4 *) Printing element according to one   of claims 1 to 3, characterized in that   the support element (3) is a thermosetting material   where appropriate reinforced by fibers, and   plate, disc or cylinder shape.   ') Printing element according to any one   of claims 1 to 3, characterized in that   the support element (3) is in the form of an element   laminated with a varnish of support.   6 ') Printing element according to any one   conque of claims i to 5, characterized in that   the support element (3) has a thickness of between 0.02 and 10 mm.   7 ') Printing element according to one   any of claims i to 6, characterized in that   that the support element (3) is formed of a layer of   (5), a plastic tape (6), double-sided sticky or adhesive and a plate of support (7).   8 ') Process for producing a printing element for copying microstructures, characterized in the following steps: a) a sheet material is swollen in a solvent, b) a solution sheet is formed by homogenizing   the material of the leaf by a freezing step   (c) applying the sheet in solution to the copying surface having the microstructure, d) drying the sheet in solution to form a copying layer (2) on the copying surface, having the microstructure, e) on forms a printing blank (8) by reinforcing the copy layer (3) on the copying surface by applying a supporting element (3), f) removing the printing blank (8) from the surface presenting the microstructure, g) forming a printing element by applying an optical layer (1) to the microstructure of the printing blank (8).   9) Process according to claim 8, characterized in that the solvent is acetone and the material constituting the sheet is triacetate of cellulose.   Process according to any one of   8 and 9, characterized in that the material constituting the sheet is allowed to rest in a solvent at a temperature of between 280 K and   325 * K for 0.5 to 3 hours to inflate.   11 ') Process according to any one of the   Claims 8 to 10, characterized in that the freezing step consists in cooling the swollen sheet material to temperatures between 77 K and 175 K with exclusive reheating by shaking the liquid phase up to 280 K.   12 ') Process according to any one of the   Claims 8 to 11, characterized in that the freezing step is effected by evaporating a refrigerating agent having a boiling point of between K and 90 ° C. (13) Process according to any one of   Claims 8 to 12, characterized in that the   leaf in solution contains between 20 and 200 liters of   solvent per kg of material constituting the sheet.   14 ') Process according to any one of   Claims 8 to 13, characterized in that homoge   first of all a concentrate of the leaf in   solution with 10 liters of solvent for 1 kg of   the material constituting the sheet passing through the freezing step and before the implementation of the sheet in solution as a copy layer (2) dilute this concentrate.   15 ') Process according to any one of   8 to 14, characterized in that the sheet is applied in solution by painting, by spraying or by projection.   16 *) Process according to any one of   Claims 8 to 15, characterized in that it is dry   the sheet in solution after its application at temperatures between 280'K and 320K for a period from i to 30 seconds.   17 ') Process according to any one of the   Claims 8 to 16, characterized in that it applies   the support element (3) as paint, as spraying   as a primer, in the form of a laminate, in the form of   casting, in pressed form or by injection.   18 ') Process according to any one of   Claims 8 to 17, characterized in that   that a layer (1) increasing the optical contrast and having a thickness of between 0.01 pm and 0.3 pm   by spraying, spraying or chemical deposition.