EP0445959A1 - Grainage électrolytique - Google Patents

Grainage électrolytique Download PDF

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Publication number
EP0445959A1
EP0445959A1 EP91301602A EP91301602A EP0445959A1 EP 0445959 A1 EP0445959 A1 EP 0445959A1 EP 91301602 A EP91301602 A EP 91301602A EP 91301602 A EP91301602 A EP 91301602A EP 0445959 A1 EP0445959 A1 EP 0445959A1
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EP
European Patent Office
Prior art keywords
aluminium
electrolyte
alternating current
graining
sheet
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.)
Withdrawn
Application number
EP91301602A
Other languages
German (de)
English (en)
Inventor
Philip Adrian Atkinson
Nicholas James Brattan
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.)
Du Pont UK Ltd
Original Assignee
Du Pont UK Ltd
Du Pont Howson 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.)
Filing date
Publication date
Application filed by Du Pont UK Ltd, Du Pont Howson Ltd filed Critical Du Pont UK Ltd
Publication of EP0445959A1 publication Critical patent/EP0445959A1/fr
Withdrawn legal-status Critical Current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
    • B41N3/00—Preparing for use and conserving printing surfaces
    • B41N3/03—Chemical or electrical pretreatment
    • B41N3/034—Chemical or electrical pretreatment characterised by the electrochemical treatment of the aluminum support, e.g. anodisation, electro-graining; Sealing of the anodised layer; Treatment of the anodic layer with inorganic compounds; Colouring of the anodic layer
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/02—Etching
    • C25F3/04—Etching of light metals

Definitions

  • This invention relates to the electrolytic graining of aluminium, aluminium alloys and aluminium laminates and more particularly, but not exclusively, is concerned with the electrolytic graining of aluminium, aluminium alloys or aluminium laminates in the production of substrates suitable for use in the manufacture of radiation sensitive plates in lithographic printing plate production.
  • Radiation sensitive plates of the type with which this invention is concerned conventionally consist of a substrate onto which is coated a radiation sensitive composition. Image-wise exposure of the plate to radiation causes the coating to change its characteristics in the areas struck by radiation so that the coating may be selectively removed from the substrate in the non-image areas by application of a suitable developer to leave a printing image (or etch resistant area) on the substrate. In the case of the so-called negative-working devices, it is the non-radiation struck areas of the coating which are removed. Those parts of the coating which are not removed and which thus form the printing image are ordinarily water-repellent and ink-receptive and those parts of the substrate revealed on development are ordinarily water-receptive and ink-repellent.
  • the surface of the substrate should be such that the printing image can strongly adhere thereto and such that it is readily wettable with water. It is known to improve the adhesion of the printing image and to improve the wetting characteristics of the non-image areas by roughening (conventionally referred to as graining) the substrate before applying the radiation sensitive coating.
  • the coarseness or surface roughness of the grained substrate can be characterised, for example, by measurement of a centre line average (CLA).
  • CLA centre line average
  • the type of grain required for the substrate of a radiation sensitive printing plate for lithographic printing plate production depends upon the requirements of the final printing plate.
  • a fine grain - i.e. shallow depressions - results in better reproduction of half-tones
  • a coarse grain - i.e. deep depressions - results in the non-image areas having better wetting characteristics.
  • it is important that the depressions are evenly spaced over the substrate surface and that they are close enough together so that peaks, rather than plateaux, are formed between the depressions.
  • Graining is normally effected by immersing the substrates in a suitable electrolyte and subjecting them to a sine waveform alternating current.
  • hydrochloric acid has been used as the electrolyte for graining aluminium and aluminium alloy substrates.
  • hydrochloric acid it is difficult to obtain a fine homogeneous grain and it is therefore necessary carefully to control the acid concentration of the electrolyte in order to ensure consistent results.
  • aluminium alloys such as 3103 aluminium maganese alloy are used as the substrate.
  • the use of such alloys for the substrate can be particularly advantageous due to their increased resistance to tearing and cracking and to temperatures in excess of 200°C which are used to harden the image on the printing plate and thus to increase the printing run length.
  • hydrochloric acid or hydrochloric acid/phosphoric acid mixtures is further disadvantageous when using certain aluminium alloys since both these electrolytes attack the impurities in the alloy and thus cause pitting of the surface.
  • hydrochloric acid in combination with monocarboxylic acids having between 1 and 4 carbon atoms.
  • monocarboxylic acids having between 1 and 4 carbon atoms.
  • aluminium and aluminium alloy substrates having a fine homogeneous grain structure can be produced.
  • complicated analytical techniques are required to monitor the relative amounts of hydrochloric acid and monocarboxylic acid.
  • additives to the hydrochloric acid electrolyte such as monocarboxylic acids can be environmentally undesirable.
  • the present invention provides a method of electrolytically graining a sheet of aluminium, aluminium alloy or aluminium laminate which comprises immersing the sheet in an aqueous electrolyte and passing an alternating current through the electrolyte wherein the alternating current has a square waveform.
  • hydrochloric acid is used, and the concentration of hydrochloric acid in the electrolyte will be from 3 to 20 gl ⁇ 1 and the electrolytic graining may preferably be effected at a voltage of, for example, 5V to 45V, particularly preferably from 10V to 35V for 15 seconds to 4 minutes to give a surface roughness characterised by a centre line average (CLA), as measured, for example, by a Rank Taylor Hobson Talysurf 10, of from 0.3 to 1.0 microns.
  • CLA centre line average
  • the electrolyte may be at any suitable temperature but preferably from 25 to 34°C.
  • An alternative to the above is to use nitric acid in which case concentrations of between 5 and 30 gl ⁇ 1 may be used.
  • the frequency of the alternating square wave current will preferably be from 20 to 100Hz and particularly preferably from 40 to 70Hz.
  • the voltage in each half cycle can be chosen as desired within the preferred range.
  • the preferred ratios of the voltage in the positive and negative half cycles are within the range of from 1:2 to 1:1, positive : negative. It is also possible to vary the time period of each half-cycle whilst maintaining the frequency within the preferred range.
  • the preferred range for the ratio of the time periods in the positive and negative half cycles is from 1:2 to 1:1, positive : negative.
  • the graining may be effected by immersing the aluminium, aluminium alloy or aluminium laminate sheet in the electrolyte, the square waveform alternating current being passed through the electrolyte using the sheet as an electrode.
  • a second similar sheet may be used as the second electrode.
  • the graining may be effected as a continuous process by passing a continuous web of aluminium, aluminium alloy or aluminium laminate through the electrolyte.
  • the electrodes used to introduce the square waveform alternating current may, for example, be carbon electrodes located near to the web.
  • the aluminium, aluminium alloy or aluminium laminate may be anodised in a suitable electrolyte, preferably using direct current. Thereafter the grained surface (or the grained and anodised surface, as the case may be) of the sheet may be coated with a radiation sensitive composition to form a radiation sensitive plate.
  • the radiation sensitive composition may be a positive working composition such as a mixture of a quinone diazide and a novolak resin or a negative working composition, such as a photopolymerisable resin.
  • the radiation sensitive plate may then be imagewise exposed and suitably processed to produce a lithographic printing plate.
  • Sheets of 3103 grade aluminium-manganese alloy were degreased in 10 to 20gl ⁇ 1 sodium hydroxide for 30s at 35 to 40°C and rinsed.
  • the sheets were then electrolytically grained using hydrochloric acid at a concentration of 7gl ⁇ 1 and a temperature of 26 to 28°C and using a square waveform alternating current at an applied voltage of 16 to 18V and at a frequency of 50Hz.
  • the resulting grained sheets had a CLA of 0.6 to 0.8 microns. Part of the surface of one sheet is shown in Figure 2.
  • Sheets of 3103 grade aluminium-manganese alloy were degreased, rinsed and grained as in Example 1, but using a sine waveform alternating current.
  • the resulting grained sheets had a CLA of 0.6 to 0.8 microns. Part of the surface of one sheet is shown in Figure 3.
  • Sheets of 3103 grade aluminium-manganese alloy were degreased and rinsed as in Example 1.
  • the sheets were then electrolytically grained using an electrolyte comprising 8 to 10gl ⁇ 1 hydrochloric acid and 15 to 30 gl ⁇ 1 of a monocarboxylic acid at a temperature of 26 to 28°C and using a sine waveform alternating current at an applied voltage of 16 to 18V and frequency of 50Hz.
  • the resulting grained sheets had a CLA of 0.6 to 0.8 microns. Part of the surface of one of the sheets is shown in Figure 4.
  • Sheets of 3103 grade aluminium-manganese alloy were degreased, rinsed and grained as in Comparative Example 2, but using a square waveform alternating current.
  • the resulting grained sheets had a CLA of 0.6 to 0.8 microns. Part of the surface of one of the sheets is shown in Figure 5.
  • Sheets of 1050 grade aluminium (99.5%Al) were degreased, rinsed and grained using the same conditions as Example 1. Part of the surface of one of the sheets is shown in Figure 6.
  • Sheets of 1050 grade aluminium were degreased, rinsed and grained using the same conditions as Comparative Example 1. Part of the surface of one of the sheets is shown in Figure 7.
  • Sheets of 1050 grade aluminium were degreased, rinsed and grained using the same conditions as Comparative Example 2. Part of the surface of one of the sheets is shown in Figure 8.
  • Sheets of 1050 grade aluminium were degreased, rinsed and grained using the same conditions as Comparative Example 3. Part of the surface of one of the sheets is shown in Figure 9.
  • Sheets of 3103 grade aluminium-manganese alloy were degreased in 10 to 20gl ⁇ 1 sodium hydroxide for 30 seconds at 35 to 40°C and rinsed. The sheets were then electrolytically grained using nitric acid at a concentration of 16gl ⁇ 1 and a temperature of 26-28°C. A square waveform at a frequency of 50 Hz and voltage of 18-20V was used. The resulting grained sheets had a CLA of 0.6 to 0.8 microns.
  • Sheets of 3103 grade aluminium-manganese alloy were degreased, rinsed and grained as in Example 7, but using a sine waveform.
  • the resulting grained sheets had a CLA of 0.6 to 0.8 microns.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Printing Plates And Materials Therefor (AREA)
EP91301602A 1990-03-06 1991-02-27 Grainage électrolytique Withdrawn EP0445959A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9005035 1990-03-06
GB909005035A GB9005035D0 (en) 1990-03-06 1990-03-06 Improvements in or relating to electrolytic graining

Publications (1)

Publication Number Publication Date
EP0445959A1 true EP0445959A1 (fr) 1991-09-11

Family

ID=10672117

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91301602A Withdrawn EP0445959A1 (fr) 1990-03-06 1991-02-27 Grainage électrolytique

Country Status (12)

Country Link
EP (1) EP0445959A1 (fr)
JP (1) JPH0770800A (fr)
AU (1) AU7197691A (fr)
BR (1) BR9100958A (fr)
CA (1) CA2037594A1 (fr)
CS (1) CS58091A3 (fr)
FI (1) FI910745A (fr)
GB (1) GB9005035D0 (fr)
HU (1) HUT57129A (fr)
IE (1) IE910722A1 (fr)
NO (1) NO910882L (fr)
ZA (1) ZA911605B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2358194A (en) * 2000-01-17 2001-07-18 Ea Tech Ltd Electrolytic treatment using non-sinusoidal alternating current

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4412678A (en) * 1979-06-18 1983-11-01 Turco Manufacturing Co. Saddle for bar and bar-type weight

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0129338A2 (fr) * 1983-05-19 1984-12-27 Fuji Photo Film Co., Ltd. Procédé de traitement électrolytique
DE3836810A1 (de) * 1987-10-30 1989-05-18 Fuji Photo Film Co Ltd Verfahren zur herstellung eines aluminiumtraegers einer druckplatte
DE3910450A1 (de) * 1988-03-31 1989-11-09 Fuji Photo Film Co Ltd Verfahren zur herstellung eines druckplattentraegers aus aluminium

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0129338A2 (fr) * 1983-05-19 1984-12-27 Fuji Photo Film Co., Ltd. Procédé de traitement électrolytique
DE3836810A1 (de) * 1987-10-30 1989-05-18 Fuji Photo Film Co Ltd Verfahren zur herstellung eines aluminiumtraegers einer druckplatte
DE3910450A1 (de) * 1988-03-31 1989-11-09 Fuji Photo Film Co Ltd Verfahren zur herstellung eines druckplattentraegers aus aluminium

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2358194A (en) * 2000-01-17 2001-07-18 Ea Tech Ltd Electrolytic treatment using non-sinusoidal alternating current
GB2358194B (en) * 2000-01-17 2004-07-21 Ea Tech Ltd Electrolytic treatment

Also Published As

Publication number Publication date
NO910882D0 (no) 1991-03-06
AU7197691A (en) 1991-09-12
BR9100958A (pt) 1991-11-05
IE910722A1 (en) 1991-09-11
GB9005035D0 (en) 1990-05-02
CA2037594A1 (fr) 1991-09-07
FI910745A0 (fi) 1991-02-15
ZA911605B (en) 1991-12-24
HUT57129A (en) 1991-11-28
HU910713D0 (en) 1991-09-30
JPH0770800A (ja) 1995-03-14
CS58091A3 (en) 1992-04-15
NO910882L (no) 1991-09-09
FI910745A (fi) 1991-09-07

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