GB1588780A

GB1588780A - Process and device for the separation of laminates

Info

Publication number: GB1588780A
Application number: GB31744/77A
Authority: GB
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1976-07-31
Filing date: 1977-07-28
Publication date: 1981-04-29
Also published as: BE857280A; DE2634560A1; JPS5317334A; CA1093366A

Description

(54) PROCESS AND DEVICE FOR THE SEPARATION OF LAMINATES (71) We, HOECHST AKTIENGESELL SCHAFT, a body corporate organised according to the laws of the Federal Republic of Germany, of 6230 Frankfurt/Main 80, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process and a device for the separation of laminates, especially for use in connexion with reprographic laminates, for example, layer transfer materials.

Layer transfer materials are frequently used for the manufacture of printed circuits; they consist, for example, of a light-sensitive layer (the so-called photo resist layer), which is enclosed between two films of different polymers, one acting as the carrier film and one as the cover film. The two films exhibit, as a rule, different degrees of adhesion to the light-sensitive layer and are in this way intended to permit controlled one-sided removal (delamination). The film which can be peeled off relatively more easily, or the film to be peeled off first, is known as the cover film, and the other is known as the carrier film. Such layer transfer materials, which are referred to in the trade as dry resist films, are described, for example, in German Auslegeschrift No. 1 522 515, British Patent Specification No. 1 379 229 and German Offenlegungsschrift No. 2 205 146; the light-sensitive layer is usually a photopolymerizable layer.

The layer transfer is in general carried out by laminating the surface of the lightsensitive layer, exposed after removing the cover film, onto the final base, for example a copper/aluminium bimetallic plate or a plastics plate with a laminated copper skin, for example by warming and pressure.

After the laminate thus produced has been exposed to light, through the carrier film, the carrier film is pulled off.

For the initially one-side delamination required for the layer transfer it is necessary, inter alia, that the adhesion of the cover film is significantly less than that of the carrier film, but is just still sufficient to allow the production of a temporarily stable laminate which on storage and processing remains intact for as long as necessary so that, for example, no one-side detachment of a film web nor any migratory entry or occlusion of air or oxygen takes place. This is necessary because the occlusion of oxygen or air leads, in the case of light-sensitive photomonomer layers capable of addition polymerisation, to undesired side-reactions, and hence to a reduction of the light sensitivity.

For the delamination of the carrier film layer, required after layer transfer and exposure, it is furthermore necessary that the adhesion of the carrier film to the lightsensitive layer should be less than the adhesion of the light-sensitive layer to the metallic base, for example copper, to which the layer is transferred. A noticeable disadvantage of such a construction in connection with previously proposed delamination and lamination techniques is, for example, the technically and commercially expensive necessity of using films with different adhesive properties, matched to the light-sensitive layer.

In practice, at the present time, polyethylene is frequently used as the cover film and biaxially stretched polyethylene terephthalate as the carrier film; these films exhibit different degrees of adhesion to lightsensitive layers in current use.

The polyethylene films employed as cover films originate mainly from the packaging industry, which is primarily interested in making films as cheaply as possible. These films tend, therefore, to be of inferior quality; for example, their dimensional stability, in contrast to that of the polyethylene terephthalate films used as carrier films, tends to be inadequate, they are frequently of uneven thickness due to occluded specks, and are furthermore of varying permeability to various gases and vapours. The disadvantages of these properties are clear. Even with different degrees of adhesion of the carrier films and covering films to the light-sensitive layer, for example with a difference of 5 g/100 mm, delamination on the wrong side of the laminate can easily occur owing to factors which determine the quality or prevail during manufacture, and this cannot be prevented reliably with previously proposed delamination and lamination processes and machinery. Such factors include, for example, specks pressed into the resist layer, adhesion caused by exposure of the lightsensitive coating composition at the cut edges of the roll, irregularities in cut at the edge of the roll, occurring during slitting, towards the end of the life of the cutter, and uneven winding or blocking phenomena between the resist film webs on the roll.

Accordingly, using previously proposed lamination and delamination devices, a lightsensitive layer enclosed between two films of the same type is even less capable of being delaminated in a controlled manner and on the correct side.

Devices which can be used, for example, for applying a light-sensitive layer to the base to be laminated, namely so-called laminators, have already been proposed. The devices described in U.S. Patent Specification No. 3 143 454 and U.S. Patent Specification No. 3 309 983 are suitable, inter alia. for enclosing identity carriers between two heatsealable films of the same type, the films being fed from two separate rolls. Another laminator, having a special laminating roll construction, is described in U.S. Patent Specification No. 3 401 439. Perfect delamination is only readily possible. with laminates manufactured by means of such devices or similar devices, if the covering films and carrier films exhibit very different degrees of adhesion to the light-sensitive layer, that is to say, if the adhesion of the carrier film is at least twice as great as tliat of the cover film.

If the device according to U.S. Patent Specification No. 3 401 439, which is suitable for laminating, is also used for delaminating a laminate suitable for the layer transfer of a light-sensitive layer. the separation of, for example, the polyolefin cover film from the light-sensitive layer applied to polyester carrier film is effected by removing the cover film from the laminate in the running direction of the film. Perfect delamination is, in the case of this device also, only possible if films having very different degrees of adhesion to the light-sensitive layer are present; frequently, blocking effects on the running and heating rolls, or other disturbing adhesive forces of external origin, also occur in such eases.

A device for applying to a carrier material a light-sensitive layer, the said layer being laminated between a carrier layer and a cover layer, is described in U.S. Patent Specification No. 3,404,057. This device includes, inter alia, means for stripping the cover layer from the residual laminate consisting of the carrier layer and the lightsensitive layer. The stripping means, advantageously a stripping roll, is driven at a higher speed than the device by means of which the laminate is transported. Accordingly, the delamination process occurs, in this device, by a directional change caused by a roller, and as a result the difficulties already indicated again occur, so that only laminates in which the cover film and carrier film posses different degrees of adhesion to the light-sensitive layer can be delaminated.

The present invention provides a process for the separation of a first, outer, layer of a laminate which also comprises second and third layers, in which process the laminate is moved and the first layer is deflected from the second and third layers at an angle of more than 90" and up to 1800 to the direction of movement of the laminate immediately before separation, one of the second and third layers being a removable carrier layer.

The first layer is deflected from the second and third layers in a direction counter to the direction of movement of the laminate immediately before separation. The expression "counter to the direction of movement of the laminate" means that the component of the deflection direction parallel to the direction of movement of the laminate is in the opposite direction to the said direction of movement.

The obtuse angle between the deflection direction and the direction of movement of the laminate, hereinafter referred to as the angle of deflection, is preferably more than or equal to 140 The process according to the invention is suitable in general for the separation of first, outer, layers of laminates which also comprise second and third layers, but is especially suitable for use in connexion with laminates constructed as layer transfer materials and consisting of a pair of films with a light-sensitive, preferably thermoplastic, layer enclosed between them. In the simplest case, the pair of films used can consist of different materials, such as are employed in the dry resist films currently available on the market The process according to the invention may, however he used particularly advantageously if it is intended to separate laminates whereof the two films possess the same, or virtually the same, degree of adhesion to the light-sensitive layer which they enclose.

Identical adhesion is encountered when the cover film and the carrier film consist of the same material or, alternatively, when the cover film and carrier film are different from one another but have received identical adhesion-promoting pre-treatment to improve their surface properties.

French Patent Specification No. 1 421 605 describes a device for labelling cylindrical articles. In this device, a row of self-adhesive labels carried on a carrier strip is conveyed to a point of separation where the carrier strip is deflected over the sharp edge of a separator plate in order to detach it from each label in turn, the detached labels being taken up by a perforated drum against the surface of which they are held by suction; the labels are then transferred by the rotation of the drum to a labelling station where they are applied successively to a series of cylindrical articles.

In this process, however, the laminate is of a different type, and only one of the outer layers has to be peeled off during the entire processing, whilst the other, namely the label layer, always remains bonded to the adhesive, so that its adhesion to the adhesive is irrelevant relative to the adhesion between the layer to be peeled off and the adhesive; the label layer is not a removable carrier layer. Furthermore, the layer materials used in this laminate, such as paper, adhesive and release paper, differ substantially from the laminate materials for which the process of the present invention is particularly suitable, namely films and a light-sensitive composition.

In the process of the present invention, the cover film is preferably deflected around a deflection edge provided, for example, by a wedge-shaped doctor blade, or by a rod or wire extending across the path of travel of the laminate. If a wedge-shaped doctor blade is used, its edge may be either sharp or slightly rounded.

The process according to the invention can, under certain conditions, also be carried out by deflecting the covering film uniformly from the laminate without the use of a deflection edge. This is true in particular if the cover film consists of the same plastics material as the carrier film, but is thinner.

The cause of this special effect may possibly be that the thinner of the two films can be curved more easily or more strongly, that is to say, that the radius of the semi-circular of curvature, formed at the point of reflection of the covering film from the remainder of the laminate, is smaller. If, for example, the laminate consists of a carrier film of polyester having a thickness of about 23 pm, a light-sensitive layer having a thickness of about 25 Fm, and a cover film of polyester having a thickness of about 8 to 15 ,jam, preferably of about 10 to 13 ym, the cover film can be uniformly stripped from the laminate, without using a deflection edge device, at an obtuse angle of deflection counter to the running direction of the laminate.

The process of the invention makes it possible, in a laminate, to effect the removal of a cover layer without damaging the intermediate layer, as a result of which the intermediate layer, for example a lightsensitive layer, remains adhering completely, that is to say with its entire surface, to the carrier film.

After removal of the cover film by the process of the invention, the residual laminate consisting of the light-sensitive layer and the carrier film may be laminated onto a base material, for example by means of heat and pressure. The process of the invention may thus be used in the production of printed circuits, the final base being an electrically conductive material, for example, a -copper/aluminium bimetallic plate or a plastics plate with a laminated copper skin.

The present invention further provides apparatus for separating a first outer, layer of film or web material from a laminate which is in the form of an elongate web and which also comprises second and third layers, which comprises (a) means for transporting the laminate in a direction parallel to its longitudinal axis, along a path of travel, (b) means for deflecting the first layer from the second and third layers at an angle that is more than 90" and up to 1800 to the direction of movement of the laminate immediately before separation, the said means including an edge trans verse to the path of travel around which the said outer layer is to be deflected and further including means for varying the angle at which the first layer is deflected, (c) means for transporting away the separ ated first layer, and (d) means for transporting away the web material remaining after removal of the first layer.

The apparatus may further include means for laminating the residual web material (in the preferred case, the carrier film and the light-sensitive layer) onto a base material in such a way that that face of the material that was protected by the cover film comes into contact with the new base material.

A preferred device according to the invention thus consists of means for unwinding the laminate from a supply roll, means for deflecting the cover film from the laminate, means for winding up the removed cover film, means for laminating the remaining laminate (carrier film and light-sensitive layer) onto a base material, especially for the manufacture of circuit boards, and means for transporting the laminate, the removed cover film and the residual laminate, within the device, the deflection means being of sharp-edged construction and additionally possessing means for the variable setting of the angle between the running direction of the laminate and the running direction of the removed cover film.

Various embodiments of the invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of an example of the process and apparatus of the invention, Figure 2 shows a part of Figure 1 on a larger scale.

Figure 3 shows a cross-section of ap Apparatus according to the invention Figures 4 and 5 show, in cross-section, alternative constructions for the deflection device.

Referring now to Figures 1 and 2 of the drawings, the laminate 1, consisting of a cover film 2 and a carrier film 10 with a thermoplastic light-sensitive layer 15 arranged between them, is passed underneath a deflection device 3. At the tip of the deflection device which is in the form of a wedg-shaped doctor blade having the crosssectional shape of an acute-angled triangle, the cover film 2 is removed from the laminate by being deflected around the sharp or rounded edge. The residual laminate 4 is then transported over a heating shoe 5 and is laminated, between a transport roller 6 and a pressure roller 7, onto a base material 8, for example a plastics/coppcr shect for the manufacture of printed circuits. The now laminate 9 can then be conveyed away to a further processing operation.

The laminate 1 is moved, in a running direction 13, towards the broad end of the deflection device 3 and changes its running direction, at the lower edge of this broad end, to a new direction 12, so as to ensure taut tensioning of the laminate web. At the tip of the deflection device, the cover film 2 is separated from the residual laminate 4 by being deflected about this tip into a new direction 14. The angle of deflection a can be set by means of the adjustable setting device 11; its maximum value is equal to the supplement of the angle of the tip of the deflection device, whilst its minimum value is advantageously not less than 1400.

The angle of deflection ot is, of course, the angle between the running direction 12 (of the laminate) and the running direction 14 (of the stripped-off cover film). The residual laminate 4 consisting of the light-sensitive layer 15 and carrier film 10 is, for example, passed on to the further processing step described above.

Referring now to Figure 3, the apparatus includes a supply roll 17 with a wind-off core 16, from which the laminate 1, consisting of the films 2 and 10 and the lightsensitive layer 15, is unwound; the cover film 2 is deflected about the wedge-shaped doctor blade 3 and thereby automatically removed from the laminate. The angle of deflection ,cg can be variably controlled by the means 11. The reference numeral 18 denotes intermediate transport rolls for cover film and for the laminate. The cover film 2 is wound up as a roll 20 on a wind-up core 19; the wind-up cores 19 and 16 are connected to one another and to the transport roll 6 in such a way as to ensure constant speed of the individual sections of web relative to one another. The residual laminate 4 consisting of the light-sensitive layer 15 and the carrier film 10 is laminated onto a base material 8, to be fed in, between the transport roller 6 and the pressure roller 7.

Instead of a wedge-shaped doctor blade, it is possible to use a deflection rod 21, the diameter of which is preferably not more than 5 mm (see Figure 4). A further embodiment of the invention provides that the separation of the laminate can be effected by means of a wire 22 tensioned across the width of the device (see Figure 5).

The following Examples illustrate the invention.

Example 1 A 25 pm thick polyethylene terephthalate film was coated with a mixture of a photomonomer (200 g) consisting of the reaction product of 2,2,4-trimethyl-hexamethylene diisocyanate with 2-hydroxyclhy] methacrylate and a terpolymer (200 g) consisting of n-hexyl methacrylate, methacrylic acid and styrene, to which the following substances were also added: 9-phenyl-acridine (6.15 g), Michler's ketone (0.46 g), triethylene glycol dimcthacrylate (4.6 g) and Samarone Navy Blue HGL (1.07 g).The coating solution was first brought to a viscosity of 60-70 cSt (at 25"C- by adding methyl ethyl ketone.

After the 45 pm thick light-sensitive layer had been dried at 1300C, the cover film, the thickness and composition of which correspond to those of the carrier film used, was laminated on.

In order to laminate the light-sensitive layer onto a conductor plate, one of the two polyester films was removed from the laminate by deflection about the tip of a wedgeshaped doctor blade at an angle of deflection of 155 and the light-sensitive layer remaining on the other polyester film was then applied to the conductor plate in the usual manner.

Example 2 The coating solution described below was applied to a 25 pm thick polyethylene terephthalate film and dried at 1200C: 2.8 parts by weight of a terpolymer of methyl methacrylate, n-hexyl methacrylate and methacrylic acid (75 parts by weight: 375 parts by weight: 90 parts by weight), having an acid number of 209; 2.8 parts by weight of the photomonomer, containing urethane groups, described in Example 1; 0.2 part by weight of 9-phenyl-acridine; 0.25 part by weight of triethylene glycol diacetate; 0.03 part by weight of tri-4-(3-methylphenylamino)-phenyl-methyl acetate and 30 parts by volume of ethylene glycol monoethyl ether.

An approx. 25 pm thick polypropylene film, the adhesion of which did not differ, or differed only slightly, from that of the carrier film (surface tension about 38 mN/m) was then laminated onto the 25 pm thick light-sensitive layer and the laminate was stored in rolls.

To manufacture circuit plates or the like, the polypropylene cover film was removed, by deflection about a rod of 3 mm diameter, with an angle of deflection of 165 , in such a way that the light-sensitive layer remained adhering, over its entire surface, to the carrier film and could be further processed, to produce circuit plates, in the usual manner with the aid 'bf laminators.

Example 3 A laminate was prepared that consisted of a 25 pm thick film of Chill Roll high pressure polyethylene having a melt index of 2, a 25 pm thick film of polyethylene tere phthalate, and, between them, a 40 pm thick light-sensitive intermediate layer pro duced by drying a solution having the following composition at about 1200C: a copolymer of 37% styrene and 63% monobutyl maleate, molecular weight 20 000, (67 g), trimethylolpropane triacrylate (22 g), tetraethylene glycol diacrylate (11 g), benzophenone (2.3 g), 4,41-bis-(dimethyl-amino)benzophenone (0.3 g), 2,21-methylene-bis (4-ethyl-6-tert. butylphenol) (0.1 g), Methyl Violet 2 B base (0.07 g), benzotriazole (0.20 g) and methyl ethyl ketone (140.0 g).

Attempts to remove the polyester film without using the process and device of the invention were not successful; the lightsensitive layer remained adhering partially to both films, or only to the polyester film.

It was possible, however, to remove the poryester film by deflecting it about the wedge shaped doctor blade of the device described in Example 1. The polyester film was separ ated uniformly and over its entire surface.

Example 4 The procedure described in Example 3 was repeated, except that instead of the polyester film, the polyethylene film was deflected away from the laminate about the doctor blade. The light-sensitive layer separ ated over its entire surface from the poly ethylene film and remained firmly bonded to the polyester film. The separation was effected at a speed of the film web of 2 m/min, and the subsequent lamination.of the light-sensitive layer onto the copper surface of the circuit plate material took place at the same speed. After exposure to light, through the polyester film, of the lightsensitive layer applied to copper, the cover ing polyester film was easily peeled off without damaging the light-sensitive layer.

Example 5 A 23 pm thick polyester film onto which a 25 pm thick light-sensitive layer of the composition shown below had been applied, the layer subsequently having been dried at about 1300C, was laminated with a polyester film which was 12 pm thick but had the same chemical composition as the first mentioned film, and the laminate was wound up.

The coating solution used was a mixture composed of a photomonomer (200 g), con sisting of the reaction product of 2,2,4-tri- methyl-hexamethylene diisocyanate with 2hydroxyethyl methacrylate, and a terpolymer (200 g) of n-hexyl methacrylate, methacrylic acid and styrene; this mixture further more contained 6.15 g of 9-phenylacridine, 0.46 g of Michler's ketone, 4.6 g of triethylene glycol dimethacrylate and 1.07 g of Samarone Navy Blue HCL. The coating solution was first brought to a viscosity of 60-70 cSt (at 250 C) by adding methyl ethyl ketone.

The cover film and the carrier film consisted of biaxially stretched polyethylene terephthalate film conforming to the VDE standards for insulating materials No. 0304 (1959) and 0345 (1969), the film being of optical quality with not more than 1 to, 2 per m2 relatively highly condensed particles (specks) no longer detectable with the naked eye, of less than 0.5 mm , and not more than 30 per m2 optically non-obiectionable bubbles of less than 0.5 mm . The tensile strength of the film was 170 N/mm2 in the longitudinal and transverse directions, the elongation at break was greater than 60% in both directions, and the shrinkage was about 2% in the longitudinal and transverse directions at 1500/15 minutes.

The laminate was processed in the manner described in Example 1.

WHAT WE CLAIM IS:- 1. A process for the separation of a first, outer, layer of a laminate which also comprises second and third layers, in which process the laminate is moved and the first layer is deflected from the second and third layers at an angle 9f more than 90" and up to 1800 to the direction of movement of the laminate immediately before separation, one of the second and third layers being a removable carrier layer.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. having an acid number of 209; 2.8 parts by weight of the photomonomer, containing urethane groups, described in Example 1; 0.2 part by weight of 9-phenyl-acridine; 0.25 part by weight of triethylene glycol diacetate; 0.03 part by weight of tri-4-(3-methylphenylamino)-phenyl-methyl acetate and 30 parts by volume of ethylene glycol monoethyl ether. An approx. 25 pm thick polypropylene film, the adhesion of which did not differ, or differed only slightly, from that of the carrier film (surface tension about 38 mN/m) was then laminated onto the 25 pm thick light-sensitive layer and the laminate was stored in rolls. To manufacture circuit plates or the like, the polypropylene cover film was removed, by deflection about a rod of 3 mm diameter, with an angle of deflection of 165 , in such a way that the light-sensitive layer remained adhering, over its entire surface, to the carrier film and could be further processed, to produce circuit plates, in the usual manner with the aid 'bf laminators. Example 3 A laminate was prepared that consisted of a 25 pm thick film of Chill Roll high pressure polyethylene having a melt index of 2, a 25 pm thick film of polyethylene tere phthalate, and, between them, a 40 pm thick light-sensitive intermediate layer pro duced by drying a solution having the following composition at about 1200C: a copolymer of 37% styrene and 63% monobutyl maleate, molecular weight 20 000, (67 g), trimethylolpropane triacrylate (22 g), tetraethylene glycol diacrylate (11 g), benzophenone (2.3 g), 4,41-bis-(dimethyl-amino)benzophenone (0.3 g), 2,21-methylene-bis (4-ethyl-6-tert. butylphenol) (0.1 g), Methyl Violet 2 B base (0.07 g), benzotriazole (0.20 g) and methyl ethyl ketone (140.0 g). Attempts to remove the polyester film without using the process and device of the invention were not successful; the lightsensitive layer remained adhering partially to both films, or only to the polyester film. It was possible, however, to remove the poryester film by deflecting it about the wedge shaped doctor blade of the device described in Example 1. The polyester film was separ ated uniformly and over its entire surface. Example 4 The procedure described in Example 3 was repeated, except that instead of the polyester film, the polyethylene film was deflected away from the laminate about the doctor blade. The light-sensitive layer separ ated over its entire surface from the poly ethylene film and remained firmly bonded to the polyester film. The separation was effected at a speed of the film web of 2 m/min, and the subsequent lamination.of the light-sensitive layer onto the copper surface of the circuit plate material took place at the same speed. After exposure to light, through the polyester film, of the lightsensitive layer applied to copper, the cover ing polyester film was easily peeled off without damaging the light-sensitive layer. Example 5 A 23 pm thick polyester film onto which a 25 pm thick light-sensitive layer of the composition shown below had been applied, the layer subsequently having been dried at about 1300C, was laminated with a polyester film which was 12 pm thick but had the same chemical composition as the first mentioned film, and the laminate was wound up. The coating solution used was a mixture composed of a photomonomer (200 g), con sisting of the reaction product of 2,2,4-tri- methyl-hexamethylene diisocyanate with 2hydroxyethyl methacrylate, and a terpolymer (200 g) of n-hexyl methacrylate, methacrylic acid and styrene; this mixture further more contained 6.15 g of 9-phenylacridine, 0.46 g of Michler's ketone, 4.6 g of triethylene glycol dimethacrylate and 1.07 g of Samarone Navy Blue HCL. The coating solution was first brought to a viscosity of 60-70 cSt (at 250 C) by adding methyl ethyl ketone. The cover film and the carrier film consisted of biaxially stretched polyethylene terephthalate film conforming to the VDE standards for insulating materials No. 0304 (1959) and 0345 (1969), the film being of optical quality with not more than 1 to, 2 per m2 relatively highly condensed particles (specks) no longer detectable with the naked eye, of less than 0.5 mm , and not more than 30 per m2 optically non-obiectionable bubbles of less than 0.5 mm . The tensile strength of the film was 170 N/mm2 in the longitudinal and transverse directions, the elongation at break was greater than 60% in both directions, and the shrinkage was about 2% in the longitudinal and transverse directions at 1500/15 minutes. The laminate was processed in the manner described in Example 1. WHAT WE CLAIM IS:-

1. A process for the separation of a first, outer, layer of a laminate which also comprises second and third layers, in which process the laminate is moved and the first layer is deflected from the second and third layers at an angle 9f more than 90" and up to 1800 to the direction of movement of the laminate immediately before separation, one of the second and third layers being a removable carrier layer.

2. A process as claimed in claim 1,

wherein the angle of deflection (as herein before defined) is more than or equal to 140".

3. A process as claimed in claim 1 or claim 2, wherein the first layer is deflected around an edge provided by deflection means.

4. A process as claimed in claim 3, wherein the deflection means comprises a wedge-shaped doctor blade.

5. A process as claimed in claim 3, wherein the deflection means comprises a rod extending across the width of the layer to be separated.

6. A process as claimed in claim 3, wherein the deflection means comprises a wire stretched across the width of the layer to be separated.

7. A process as claimed in claim 1 or claim 2, wherein the first layer is deflected without using a deflection edge.

8. A process as claimed in any one of claims 1 to 7, wherein the first layer is a film of plastics material.

9. A process as claimed in claim 8, wherein the film or web is of polyester or polyolefin.

10. A process as claimed in claim 9, wherein the film is of polyethylene terephthalate, polyethylene or polypropylene.

11. A process as claimed in any one of claims 8 to 10, wherein the thickness of the film is within the range of from 20 to 30 pm.

12. A process as claimed in any one of claims 1 to 11, wherein each layer'in the laminate is in the form of an elongate web.

13. A process as claimed in any one of claims 8 to 12, wherein the laminate is a dry resist film comprising a plastics carrier film, a light-sensitive layer disposed on the carrier film and a plastics cover film over the light-sensitive layer, and the process comprises separating the cover film from the combination of the light-sensitive layer and the carrier film.

14. A process as claimed in claim 13, wherein the degree of adhesion of the carrier film to the light-sensitive layer is not significantly greater than that of the cover film to the light-sensitive layer.

15. A process as claimed in claim 14, wherein both films are of the same plastics material.

16. A process as claimed in any one of claims 13 to 15, wherein the carrier and cover films are of substantially equal thickness.

17. A process as claimed in any one of claims 13 to 16, wherein the overall thick ncss of the laminate is within the range of from 80 to 100 clam.

18. A process for separating an outer layer from a laminate, carried out substantially as hereinbefore described with reference to, and as shown in, any one of Figures 1 to 5 of the accompanying drawings.

19. A process for separating a first layer from a laminate, carried out substantially as described in any one of the Examples herein.

20. A process as claimed in any one of claims 13 to 19, wherein the residual laminate consisting of the light-sensitive layer on the carrier film is subsequently so laminated onto a base material that the light-sensitive layer is adjacent to the said base material.

21. A process as claimed in claim 20, wherein the base material is electrically conductive.

22. A process as claimed in claim 21, wherein the base material comprises a copper aluminium bimetallic plate or a plastics plate having a laminated copper skin.

23. A process for the production of a printed circuit, which includes a process as claimed in claim 21 or claim 22.

24. A printed circuit whenever produced by a process as claimed in claim 23.

25. Apparatus for separatilIg a first, outer, layer of film or web material from a laminate which is in the form of an elongate web and which also comprises second and third layers, which comprises (a) means for transporting the laminate in a direction parallel to its longitudinal axis, along a path of travel, (b) means for deflecting the first layer from the second and third layers at an angle of more than 900 and up to 1800 to the direction of movement of the laminate immediately before separation, the said means including an edge trans verse to the path of travel around which the said layer is to be deflected and further including means for vary ing the angle at which the first layer is deflected, (c) means for transporting away the separ ated first layer, and (d) means for transporting away the web material remaining after removal of the first layer.

26. Apparatus as claimed in claim 25, which further comprises means for so laminating the residual web material onto a base material that the side of that material from which the first layer was removed becomes adjacent to the base material.

27. Apparatus as claimed in claim 25 or claim 26, wherein the means (b) comprises a wedge-shaped doctor blade.

28. Apparatus as claimed in claim 25 or claim 26, wherein the means (b) comprises a rod extending across the width of the path of travel of the laminate web.

29. Apparatus as claimed in claim 25 or claim 26, wherein the means (b) comprises a wire stretched across the width of the path of travel of the laminate web.

30. Apparatus for separating a first, outer, layer from a laminate, substantially as hereinbefore described with reference to, and as shown in, any one of Figures 1 to 5 of the accompanying drawings.

31. A process as claimed in claim 1, whenever carried out using apparatus as claimed in any one of claims 25 to 30.