GB1586889A

GB1586889A - Laminated glass

Info

Publication number: GB1586889A
Application number: GB34120/77A
Authority: GB
Original assignee: Pilkington Brothers Canada Ltd
Current assignee: Pilkington Glass of Canada Ltd
Priority date: 1976-09-01
Filing date: 1977-08-15
Publication date: 1981-03-25
Also published as: SE7709804L; DE2737740B2; IN147045B; FR2363438A1; MX146396A; NZ185059A; JPS5330622A; NL7709661A; BE858166A; AU2833777A; ZA775220B; AR215478A1; FI772587A7; DE2737740C3; DE2737740A1; AU510973B2; CA1038275A

Description

(54) IMPROVEMENTS RELATING TO LAMINATED GLASS (71) We, PILKINGTON BROTHERS CANADA LIMITED, of 101 Richmond St. W., Toronto, Ontario, Canada, a Canadian Company, 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: This invention is concerned with a process for producing a laminated glass, particularly laminated safety glass, a heat-reflective laminated glass or a heat reflective laminated safety glass. It is particularly well adapted to a continuous process. This invention is concerned also with the product of such a process.

The normal procedure in prior art processes has involved the use of high temperatures to cure the adhesive which joins the glass laminates or secures the plastics interlayer to the sheets of glass with which it is laminated and usually high pressures to drive out air so as to develop a product having satisfactory optical properties. Autoclaves and hot presses have commonly been used and these are costly and provide a limitation on the rate of production, as they involve a process in the nature of a batch process. Moreover, high temperatures and pressures tend to reduce reflective properties of reflective sheets used in laminated glass of the above type with the resulting undesirable reduction of the reflective quality of the final laminate.

An object of this invention is to provide a process that would overcome or at least reduce the above drawbacks by utilizing moderate temperatures and pressures so as to be adaptable to a continuous process on a conveyor.

A further object of this invention is to provide an method of removing air from within the laminate without the necessity of subjecting the laminate to high temperatures and pressures or vacuum. In particular, an object is to solve the difficult problem of satisfactorily removing air bubbles from the adhesive layer sandwiched between two glass sheets, especially when the laminate comprises an additional interlayer, such as a plastics film or heat reflective coating, disposed between the adhesive layer and one of the glass sheets.

In accordance with one aspect of the present invention, a method is provided for producing laminated glass of the type including a first sheet of glass, a second sheet of glass and an interlayer sandwiched therebetween, each of said sheets of glass having an inner surface facing said interlayer, said method comprising the steps of:: (a) securing said interlayer to the inner surface of said first sheet; (b) providing the surface of said interlayer remote from said first sheet with a layer of adhesive, said adhesive being of the type capable of anaerobic curing under generally ambient temperature conditions; (c) applying to said adhesive layer said second sheet, the application of said second sheet to the adhesive being effected at a stage wherein said adhesive is virtually free of solvent but is still in a generally uncured, tacky state, whereby a sandwiched assembly is formed;; (d) subjecting the sandwich assembly to compression by applying a pressure of about 5 to 40 kp/cm to the outer surface of said second sheet, said pressure being applied along a line coincident with the outer surface of said second sheet, extending generally transversely of said assembly from one side thereof to the other and moving longitudinally of said assembly from one end of the assembly to the other;; (e) said compression being effected at a stage wherein said adhesive layer is still in said generally uncured, tacky state, whereby said second sheet is temporarily delaminated from said interlayer along an interface area extending generally the entire width of said second sheet to provide a space between the inner surface- of said second sheet and said adhesive layer for escapement of air bubbles from a section from said adhesive generally coincident with said interface, said space being located close to, along and upstream of said line; and (f) at least partially curing said adhesive.

The term "pressure of about 5 to 40 kp/ cm" refers to the length of the line along which the pressure is being applied. Under normal conditions, it is of advantage to use pressure of about 10 kp/cm. If the pressure is less than about 5 kp/cm, the temporary delamination may not take place. On the other hand, it was found that even a considerable increase in the pressure, bringing the pressure close to the strength limits of the glass sheet, is still operable. Thus, pressures of about 40 kp/cm have been used in different tests and have produced satisfactory results. In practical application, however, one naturally tends to use as low a pressure as possible to reduce the production costs.

The above figure of about 10 kp/cm has been found satisfactory in virtually all tests carried out in accordance with the following examples. The pressure actually used is, of course, dependent on the thickness of the glass sheets used (about 90% of commercial production would be with 3 mm thick glass sheets) and on the viscosity of the applied adhesive. Those skilled in the art can readily determine the optimum moderate pressure by a trial-and-error method.

In accordance with another aspect of this invention a method is provided for producing a laminated safety glass comprising the steps of conveying a first sheet of glass having a film of flexible plastics adhered to its upper surface to an adhesive application zone, in said adhesive application zone applying to the outer surface of said plastics film a solvent-free adhesive which is capable of anaerobic curing under ambient conditions, applying to said film a second sheet of glass in registration with the first sheet of glass, conveying the assembly of the first and second sheets of glass and interposed plastics film to a pressing zone, the dwell time and temperature conditions between the adhesive application zone and the pressing zone being such that the adhesive has not gelled or is at the stage of incipient gelation, in said pressing zone applying roller pressure of about 10 kp/cm, said compression being effected at a stage wherein said adhesive layer is still in said generally uncured, tacky state, whereby said second sheet is temporarily delaminated from said interlayer along an interface area extending generally the entire width of said second sheet to provide a space between the inner surface of said second sheet and said adhesive layer for escapement of air bubbles from a section from said adhesive generally coincident with said interface, said space being located close to, along and upstream of said line, and at least partially curing the adhesive applied in the adhesive application zone under room temperature conditions. The term "gelled" in this context relates to physical change in the adhesive from a very low viscous stage to a point of partial cure. The term "incipient gelation" relates to the stage of a tacky point of the adhesive.

In accordance with another aspect of this invention a continuous process is provided for producing a laminated safety glass comprising the steps of: (a) conveying a first series of flat sheets of glass arranged end to end to a first adhesive application zone; (b) applying to a surface of each of said sheets in said first adhesive application zone a solvent-free adhesive which is capable of anaerobic curing under ambient temperature conditions; (c) conveying each of said sheets of glass to a film application zone; (d) in said film application zone applying a film of flexible plastics material to said surface of each of said sheets of glass;; (e) conveying each of said sheets of glass to a first pressing zone, the dwell time during which the sheets are conveyed to the pressing zone and the temperature conditions being such that the adhesive is gelled and tacky, but there is the possibility of limited relative movement between the plastics film and said glass sheets; (f) in said first pressing zone applying roller pressure of about 10 kp/cm to said plastics film to smooth out any wrinkles in said plastics film and to expel any air trapped between the plastics film and the glass sheets; (g) conveying said sheets to a second adhesive application zone; (h) in said second adhesive application zone applying to the outer surfaces of said plastics film a solvent-free adhesive which is capable of anaerobic curing under ambient temperature conditions;; (i) applying to said outer surface of said plastics film a second series of sheets of glass in registration with the sheets of said first series; (j) conveying the assembly of sheets of the first and second series of sheets of glass and interposed plastics film to a second pressing zone, the dwell time and temperature conditions between the second adhesive application zone and the second pressing zone being such that the adhesive applied in the second adhesive application zone either has not gelled or is at the stage of incipient gelation; ; (k) in said second pressing zone applying roller pressure of about 10 kp/cm, whereby said second sheet is temporarily delaminated from said interlayer along an interface area extending generally the entire width of said second sheet to provide a space between the inner surface of said second sheet and said adhesive layer for escapement of air bubbles from a section from said adhesive generally coincident with said interface, said space being located close to, along and upstream of said line; and (1) at least partially curing the adhesive applied in the second adhesive application zone under room temperature conditions.

This invention also includes a glass laminate comprising a pair of flat sheets of glass, an interlayer which may be a film of plastics and/or a heat-reflective metallic layer laminated between said sheets of glass and a layer of a solvent-free adhesive cured under anaerobic conditions at moderate temperature, said interlayer being adhered to an overlying sheet of glass, said laminate having been subjected to moderate rolling pressure to remove air bubbles from said layer of adhesive.

This invention may be applied to produce a safety glass laminate without a heatreflective coating, or may be used to provide a heat-reflective safety glass by including a heat-reflective metallic coating or may be used to provide a heat-reflective laminate.

The invention will now be described by way of example only, in greater detail with reference to the following Examples and the accompanying diagrammatic drawings in which: Figure 1 is a diagrammatic elevational view illustrating a first section of a process in accordance with this invention Figure 2 is a diagrammatic elevational view illustrating a second section of a process in accordance with this invention. Figure 2 represents a continuation of Figure 1.

Figure 3 is a detail plan view of a portion of the section of the process, including a roller, shown in Figure 2.

Figure 4 is a detail elevational view of the portion shown in Figure 3.

Referring now to the drawings, Figures 1 and 2 illustrate a continuous conveyor chain 10 having a driving sprocket 11 at one end driven by reduction gearing 12 from motor 13. A second sprocket 14 is at the other end of the conveyor and there is a series of intermediate supporting rollers 15 driven by sprockets at the ends of rollers 15. For convenience of illustration only some of rollers 15 are shown, but there will be an adequate number to support the glass. Rollers 15 may be fitted with annular rubber rings spread a few inches apart to provide frictional engagement with the glass.

Flat sheets of glass 16 are transferred in succession by suitable means such as suction cups from a stack (not shown) located close to sprocket 11 so that there will be a series -of sheets of glass lying end to end on the conveyor as illustrated in Figures 1 and 2.

Preferably the adjacent ends of the sheets of glass are spaced a few inches apart. Sheets of glass 16 are preferably float glass, as this provides a particularly smooth surface, but good quality plate glass may also be used.

The present invention has been successfully applied to sheets of glass of thicknesses ranging from 2mm to 6mm, however, glass thicker than 6mm can also be used.

The first step in the process should be to clean the glass and this may conveniently be carried out on the same conveyor as used to form the laminate by providing a cleaning zone. For this purpose polishing brushes 17 rotating about a vertical axis are employed using a polishing powder such as cerium oxide, following which a water spray 18 washes off - the polishing powder. Additional polishing brushes 19 rotating about a horizontal axis are then applied to ensure the removal of any residue of polishing powder. An additional water spray 20 which should use deionized water is then applied, followed by the application, as illustrated at 21, of a sensitizer such as stannous chloride to remove fats and oil and, in the case of float glass, any metallic residue. The sensitizer treatment is followed by an additional water spray 22 with deionized water.It will be appreciated that sufficient brushes or sprays will be provided to treat the full width of the glass sheets in the cleaning zone.

Where it is desired that the laminate produced in accordance with this invention should include a metallic heat reflective layer it will be convenient to include a metallizing zone to deposite a metallic film on the first series of sheets of glass. Another possibility is to metallize the sheets of the second series of sheets of glass prior to their lamination later in the process. Yet another possibility is to precoat the plastics film which will be applied later in the process with a metallic layer.

The metallizing zone, which as previously indicated is optional, comprises metal sprays 23 followed by a spray of deionized water 24. In the metallizing zone an optical coating of metal such as silver or copper may be applied using known techniques.

The next step is to dry the surface of the glass using air blowers 25 and 26.

The sheets of glass of the first series are then passed to an adhesive application zone which includes infra-red lamps 27 which preheat the glass to about 400-500C. to reduce the gel time of the subsequently applied adhesive and also complete the drying of the glass. These are followed by a roller coaster 28 which applies a layer of adhesive to the upper surface of the glass. The adhesive must be capable of curing under anaerobic conditions and at ambient temperatures. The gel time should be at least 15 minutes at ambient temperature conditions. It also should be free from solvent. It must also develop an adequate bond between the glass and the particular plastics material which will be applied later in the process.The laminate which is eventually produced should meet current specifications with respect to resistance to boiling water, fragmentation and impact resistance, such as Canadian Government Specification 12-GP-IM dated October 1975. Any adhesive which meets these requirements may be used.

For instance, satisfactory results were obtained with an adhesive made of about 70 wt.% of the resin sold by Shell Oil Canada under trade name APON, Nos. 828, 826 and 815, mixed with about 30 wt.% of hardener sold by Veba Chemie A.G. under trade name V-214. Another adhesive used in the tests is an epoxy adhesive material sold by Hysol Division of the Dexter Corporation of Olean, New York, under the trade name Hysol R8-2038. Hysol R8-2038 is the condensation product of epichlodhydrin and bisphenol A. A wide variety of hardeners are available such as primary, secondary or tertiary amines. acid anhydrides and Lewis acids.A commercially available suitable hardener is sold under the designation H-3404 and is used in the proportion of about 10:1 epoxy resin to hardener. The viscosity (Brookfield) of the mix of epoxy and hardener at 25"C. is about 500 centepoises. The gel time is about 25 minutes at 25"C. and it will cure in about 24 hours at 25"C. The cure time is shortened to about 2 hours at 60"C. Urethane adhesives are self polymerizing and may be used but are not recommended as the bond is less satisfactory than that obtained with epoxy adhesives.

The glass of the first series of sheets is then conveyed to a film application zone 29.

The film application zone 29 comprises a reel of plastics film 30a, tensioning rollers 31 and 32 and applicator roller 33 which causes a film of p]astics 30 to be laid down as the sheets of glass 16 of the first series advance along the conveyor. A rubber pressure roller 33A is located immediately below applicator roller 33 to provide a back up roller.

The plastics film is preferably a polyester such as that known under the trade name Mylar and which is supplied by E. I. Dupont of Wilmington, Delaware. With this polyester it has been found that a film thickness in the range of about 0.025 mm to about 0.125 mm may be used which is less than the thickness of polyvinyl butyral film of about 0.4 mm normally used for safety glass.

A film which is less than 0.025 mm thick is likely to cause problems of wrinkling. Other plastics films such as polymethyl methacrylate, polypropylene and polyamide may be used provided that an adequate bond is developed with the particular adhesive which is used. It has been found that, with the preferread epoxy adhesive, polyvinyl film and cellulose acetate film develop bonds which are not strong enough to withstand the rigorous test described in the following examples although they may be satisfactory for some purposes in which the laminates produced are not exposed to testing conditions. Moreover, the strength and durability of the bond depend not only on the nature of the plastics films but also on the nature of the adhesive, and plastics films that give less durable bonds with some adhesives may give good bonds with others.Film such as polyester film is commercially available having an optical layer of heat-reflective metal deposited on it and such film may be used as an alternative to providing a metallizing zone where heat-reflective properties are desired.

Following application of the film the sheets of glass are conveyed to a pressing zone. The dwell time and spacing on the conveyor should be such that the adhesive has become gelled and tacky but not hardened by the time it reaches pressure roller 35. There is therefore the possibility of limited movement between the film and the underlying glass.

It will be appreciated that the curing can be shortened by preheating the glass or by supplying heat after the adhesive has been applied. With Hysol R8-2038/H-3404 and with preheating of the glass to 40--50"C using infra-red lamps 34 a distance of about 15 feet with a conveyor travelling at 18 inches per minute has been found to be suitable. The precise combination of conditions of time and temperature indicated above are not intended to be limiting. A moderate temperature preferably not in excess of about 50"C should however be used.

In the pressing zone a rubber roller 35 acts with back up roller 35A to apply moderate pressure to smooth out any wrinkles in the plastics film and to expel any air trapped between the plastics film 30 and the glass sheet 16. A pressure of the order of magnitude of five pounds for a sheet of glass six feet in width and with rollers about 150 mm in diameter has been found to be satisfactory. Too little pressure will be ineffective but excessive pressure will squeeze out too much of the adhesive and may also damage the film. The thickness of the adhesive before pressing is about 0.3 mm. After the pressing the thickness may be approximately 0.025 mm. A cutting knife 36 may be provided to sever the plastics material between successive sheets of glass.

The next step is to apply a layer of adhesive to the upper surface of the plastics film and this is achieved by roller coater 37.

A second series of sheets of glass 38 is then successively applied in registration with the first series by being transferred in a conventional manner such as by the use of suction cups from a stack (not shown). The inwardly facing surfaces of sheets of glass 38 should first be cleaned as described in connection with the first series 16. This may conveniently be carried out by running the sheets through the cleaning zone of the conveyor to prepare a stack of clean sheets for use as the second series.

The first and second sheets of glass between which the plastics film is sandwiched are then advanced to a pressing zone where rubber roller 39 cooperates with back up roller 40 to apply rolling pressure. As illustrated in Figure 4, the rollers 39 and 40 are driven at the same rate in opposite directions of rotation by chain 41. Motor 42 drives chain 41 through drive sprocket 43.

A tension sprocket 43A is also provided.

Those skilled in the art will readily appreciate that the drive of one of the rollers may be avoided and even has to be avoided, particularly if the diameter of one of the rollers differs from that of the other. During the tests carried out with the method of the present invention, it was found that in many cases it is of advantage to provide the upper roller 39 as a freely rotating roller even if the diameter of the two rollers is the same, and to drive only the lower roller 40.

The dwell time between the application of the adhesive by roller coater 37 and pressing with rollers 39 and 40 is short, represented by about 12 feet of travel on a conveyor moving at 18 inches per minute and preheating is avoided so that the adhesive will not have gelled or at most will be at the stage of incipient gellation. Rollers 39 and 40 are spaced to accommodate the thickness of the sheets of glass together with the plastics film, the adhesive securing the plastics film to the underlying sheet of glass and the desired thickness of adhesive between the upper sheet of glass and the plastics film after pressing between rollers 39 and 40.A slight excess of adhesive is applied by roller -coater 37 which will result in moderate pressure of the order of about 10 kp/cm of length of the rollers being developed between rollers 39 and 40 as the assembly advances through the rollers 39 and 40 to squeeze out the excess adhesive. Most of the excess adhesive flows in a direction opposite to the direction of rolling. This pressure of the wedging action of the excess adhesive will cause the upper sheet of glass to bend upwardly slightly at the input side of the rollers to delaminate from the surface of the underlying plastics film 30 as illustrated at 44 in Figure 4. This will provide for the release of air from between sheet 38 and plastics film 30.As illustrated in Figure 3 an interface 45 extending across the width of the glass sheet will be apparent in plan view between an area 46 which is free from air bubbles and an area 47 which is clouded with air bubbles. This interface is normally curved and is placed some 10cm to 15cm from the rollers on the input side of the rollers.

The pressure exerted by rollers 39 and 40 must be sufficient for the delamination and interface described above to occur, but must not be such as to squeeze out an excessive amount of adhesive. The adhesive applied by roller coater 37 should be somewhat thicker than the adhesive applied earlier by roller coater 28 to give a thickness of adhesive of about 0.05 mm. before application of pressure. The thickness of the adhesive after the application of pressure is about 0.025 mm.

The laminate is then advanced to a zone where infra-red lamps 48 raise the temperature to about 40--50"C. to promote the curing of the adhesive applied by roller coater 37 so that the laminate can safetly be removed from the conveyor. It will be appreciated that as an alternative the infra-red lamps 48 could be omitted and replaced by an extended dwell time on the conveyor.

Where the desired product includes a heat reflective interlayer but safety qualities are not required, the process described above in conjunction with Figures 1 to 4 may be used employing the metallizing zone 23 but with the omission of the roller coater 28, the film application zone 29, infra-red lamps 34 and pressing zone 35.

The nature of a process in accordance with this invention and the characteristics of the product will be additionally illustrated by the following Examples: EXAMPLE I A pair of sheets of glass 3 mm thick and measuring 150 mmX 150 mm were laminated with 0.04 mm Mylar sheet with a heat-reflective silver coating using 4 litres of clear Hysol R-2038/II-3404 adhesive per 100 m2 of glass for the first or lower layer and 6 litres per 100 m2 of glass of such adhesive for the second or upper layer. The procedure described in detail in connection with Figures 1 to 4, scaled down for sample preparation, was followed. The resultant product was a reflective laminated safety glass which was optically transparent with no visible signs of air bubbles.The sample was subjected to the following tests: immersed vertically on edge in boiling water for a period of 3 hours, then immersed vertically on edge for a further period of three hours in a boil ing salt water solution, then input in a deep freeze unit with a tem perature of - 5 0C for a further period of 12 hours.

On examination at the completion of this test cycle the subject sample was found to have no signs of delamination at the edges or discoloration of the polyester film or adhesive.

EXAMPLE 11 The product tested was a laminated glass unit 420 mm x 600 mm fabricated from 2 lights of 3 mm clear glass laminated together using a 0.08 mm thick polyester film with a heat-reflective silver coating and clear Hysol R8-2038 /H-3404 adhesive. It was free from visible air bubbles. The sample was held in a manner such that the 600 mm dimension was vertical and the glass was struck in the lower centre area with a 5 kp hammer.

The sample fractured on both sides and held together firmly with no delamination.

The fracture pattern of the side struck was a random mixture of small and medium size pieces. The fracture pattern on the obverse side was fan shaped with the origin of the fracture clearly outlined at the point of striking. The pattern of fracture was similar to that experienced when tempered glass is broken.

EXAMPLE Ill Similar results to Examples I and II will be obtained where the polyester film is not coated with an optical layer of heat-reflective silver or where a layer of heat-reflective silver is applied to one of the glass sheets.

EXAMPLE IV 3650 mmx 1800 mm sheets of 6 mm thick glass with two interlayers each of a 0.2 mm thick film of polyester were laminated using 300 g (about 0.3 litres) of adhesive per 100 m2 of glass for the first or lowermost layer.

The adhesive used in this example was a mixture containing about 70 wt.% of APON 815 (trade name of Shell Oil Canada) and about 30 wit.% of the hardener No.

V-214 sold by Veba Chemie A.G. The pressure for removing wrinkles was about 7 kp/cm and was applied after about 5 minutes of dwell time following the application of the adhesive layer. The viscosity of the adhesive at the point of application was about 6 poises. Following the wrinkle removal, the adhesive was cured at 21"C (room temperature) for 8 minutes, whereupon 500 g (about 0.5 litres) of the same adhesive per 100 m2 was deposited on top of the film. A second or intermediate glass sheet was then placed on top of the second adhesive layer and subjected to the air bubble removal pressure as disclosed, of 7 kp/cm, whereupon the adhesive in the second layer was cured at 40 C for 30 minutes.

The procedure was then repeated with laminate of the first two glass sheets with the first p]astics sheet being treated as the first glass sheet at the outset.

EXAMPLE V The process of Example IV was followed in laminating six sheets of glass as described, with five interlayers as described.

EXAMPLE Vi The process of Example IV was carried out with the width and length of the interlayer sheets being greater than those of the glass sheets, with the edges of the interlayer sheets protruding over the respective edges of the glass sheets by about 2 cm on each side to form retainer means for the adhesive "bleeding" from between the second glass sheets and the first interlayer, and from between the top or third glass sheet and the second interlayer, respectively.

EXAMPLE Vll 1 wt.% of methylester was added to the adhesive mixture of Example IV to accelerate the gelation. The dwell time was reduced to about one third of that indicated in Example IV.

Those skilled in the art will appreciate from the above examples and from the foregoing disclosure, that many further modifications differing, to a greater or lesser degree from the Examples shown, may be effected wtihout departing from the scope of the present invention as recited in the accom

Claims

panying claims. WHAT WE CLAIM IS:-

1. A method for producing laminated glass of the type including a first sheet of glass, a second sheet of glass and an interlayer sandwiched therebetween, each of said sheets of glass having an inner surface facing said interlayer, said method comprising the steps of:: (a) securing said interlayer to the inner surface of said first sheet; (b) providing the surface of said interlayer remote from said first sheet with a layer of adhesive, said adhesive being of the type capable of anaerobic curing under generally ambient temperature conditions; (c) applying to said adhesive layer said second sheet, the application of said second sheet to the adhesive being effected at a stage wherein said adhesive is virtually free of solvent but is still in a generally uncured, tacky state, whereby a sandwiched assembly is formed;; (d) subjecting the sandwich assembly to compression by applying a pressure of about 5 to 40 kp/cm to the outer surface of said second sheet, said pressure being applied along a line coincident with the outer surface of said second sheet, extending generally transversely of said assembly from one side thereof to the other and moving longitudinally of said assembly from one end of the assembly to the other;; (e) said compression being effected at a stage wherein said adhesive layer is still in said generally uncured, tacky state, whereby said second sheet is temporarily delaminated from said interlayer along an interface area extending generally the entire width of said second sheet to provide a space between the inner surface of said second sheet and said adhesive layer for escapement of air bubbles from a section from said adhesive generally coincident with said interface, said space being located close to, along and upstream of said line; and Q at least partially curing said adhesive.

2. A method as claimed in claim 1, wherein said pressure is about 10 kp per cm of said line.

3. A method as claimed in claim 1 or claim 2, wherein the pressure is applied by the periphery of a pressure roller, the movement of said interface relative to said second sheet being effected by advancing said sandwiched assembly relative to the axis of said roller.

4. A method as claimed in any one of the preceding claims, wherein the integers of the assembly are continuously conveyed between and during the steps as set forth.

5. A method as claimed in any one of the preceding claims, wherein said interlayer is a metallic coating applied to the inner surface of said first sheet.

6. A method as claimed in any one of claims 1 to 4, wherein said interlayer is a polyester plastics film.

7. A method as claimed in claim 6, wherein said polyester plastics film is adhesively secured to the inner surface of the first sheet.

8. A method as claimed in claim 7, wherein the step of securing said interlayer to the inner surface of said first sheet follows the step of providing the inner surface of said first sheet with a second adhesive layer, the amount of adhesive in said second adhesive layer being less than that in said first-mentioned layer of adhesive disposed between the interlayer and the inner surface of said second sheet.

9. A method as claimed in claim 8, wherein the same type of adhesive is used in both of said adhesive layers.

10. A method as claimed in claim 8 or claim 9, wherein the second adhesive layer is in a generally cured state prior to the step of providing the surface of the interlayer remote from said first sheet with said firstmentioned layer of adhesive.

11. A method as claimed in claim 10, further including the step of removing wrinkles from said polyester plastics film prior to the curing of said second adhesive layer.

12. A method as claimed in any one of the preceding claims, wherein said firstmentioned layer of adhesive is cured under a temperature of about 40"C.

13. A method as claimed in any one of the preceding claims wherein at least one said adhesive is a solvent-free adhesive.

14. A method as claimed in claim 13, wherein at least one ,said adhesive is an epoxy polymer.

15. A method as claimed in claim 14, wherein the epoxy polymer is an epichloro ilydrin bisphenol I resin and a hardener for such resin.

16. A method as claimed in any one of claims 6 to 11, wherein said first and second sheets of glass are placed generally in registration with each other, the width of said polyester plastics film being in excess of the width of the sheets.

17. A method as claimed in claim 16, wherein the amount of adhesive in said firstmentioned layer is such as to obtain bleeding of the adhesive at the edges of the assembly on application of said moderate pressure.

18. A method as claimed in claim 3, wherein the step of applying the pressure by said pressure roller is coincident with supporting the outer surface of said first sheet by the periphery of a back-up roller such that the vertical plane coincident with the line of contact between the back-up roller and the first sheet is parallel with and closely spaced from the vertical plane coincident with the line of contact between the pressure roller and the outer surface of the second sheet, the latter plane being disposed upstream of the former.

19. A continuous method of producing a laminated safety glass comprising the steps of: (a) conveying a first series of flat sheets of glass arranged end to end to a first adhesive application zone; (b) applying to a surface of each of said sheets in said first adhesive application zone a solvent-free adhesive which is capable of anaerobic curing under ambient temperature conditions; (c) conveying each of said sheets of glass to a film application zone; (d) in said film application zone applying a flexible plastics film to said surface of each of said sheets of glass;; (e) conveying each of said sheets of glass to a first pressing zone, the dwell time during which the sheets are conveyed to the pressing zone and the temperature conditions being such that the adhesive is gelled and tacky, but there is the possibility of limited relative movement between the plastics film and said glass sheets; (f) in said first pressing zone applying roller pressure of about 10 kp/cm to said plastics film to smooth out any wrinkles in said plastics film and to expel any air trapped between the plastics film and the glass sheets; (g) conveying said sheets to a second adhesive application zone; (h) in said second adhesive application zone applying to the outer surfaces of said plastics film a solvent-free adhesive which is capable of anaerobic curing under ambient temperature conditions;; (i) applying to said outer surface of said plastics film a second series of sheets of glass in registration with the sheets of said first series; (j) conveying the assembly of sheets of the first and second series of sheets of glass and interposed plastics film to a second pressing zone, the dwell time and temperature conditions between the second adhesive application zone and the second pressing zone being such that the adhesive applied in the second adhesive application zone either has not gelled or is at the stage of incipient gelation;; (k) in said second pressing zone applying a roller pressure of about 10 kp/cm, whereby said second sheet is temporarily delaminated from said interlayer along an interface area extending generally the entire width of said second sheet to provide a space between the inner surface of said second sheet and said adhesive layer for escapement of air bubbles from a section from said adhesive generally coincident with said interface, said space being located close to, along and upstream of said line; and (I) at least partially curing the adhesive applied in the second adhesive application zone under room temperature conditions.

20. A method as claimed in claim 19 in which the adhesive applied in the first and the second adhesive application zone is an epoxy polymer.

21. A method as claimed in claim 19 or claim 20, in which the plastics film applied in the film application zone is a polyester film.

22. A method as claimed in any one of claims 19 to 21, in which the flexible plastics film applied in the film application zone is surfaced with a heat-reflecting metallic coating.

23. A method as claimed in any one of claims 19 to 21, in which a heat-reflecting metallic coating is applied to what will be an inwardly facing surface of the sheets of glass of said first series and/or said second series.

24. A method as claimed in any one of claims 19 to 21, in which a heat-reflecting coating is applied to a surface of the sheets of the first series of sheets of glass at a metallizing zone in advance of the application of adhesive to such surface in the first adhesive application zone.

25. A method as claimed in any one of claims 19 to 24, in which there is a cleaning zone in advance of the first adhesive application zone to remove fats and oils from the surface of the glass.

26. In a method for producing a laminated safety glass the steps of conveying a first sheet of glass having a film of flexible plastics adhered to its upper surface to an adhesive application zone, in said adhesive application zone applying to the outer surface of said plastics film a solvent-free adhesive which is capable of anaerobic curing under ambient conditions, applying to said film a second sheet of glass in registration with the first sheet of glass, conveying the assembly of the first and second sheets of glass and interposed plastics film to a pressing zone, the dwell time and temperature conditions between the adhesive application zone and the pressing zone being such that the adhesive has not gelled or is at the stage of incipient gelation, in said pressing zone, applying roller pressure of about 10 kp/cm, said compression being effected at a stage wherein said adhesive layer is still in said generally uncured, tacky state, whereby said second sheet is temporarily delaminated from said interlayer along an interface area extending generally the entire width of said second sheet to provide a space between the inner surface of said second sheet and said adhesive layer for escapement of air bubbles from a section from said adhesive generally coincident with said interface, said space being located close to, along and upstream of said line, and at least partially curing the adhesive applied in the adhesive application zone under room temperature conditions.

27. A method as claimed in Claim 26 in which the adhesive applied to the upper surface of the film is an epoxy polymer.

28. A method as claimed in Claim 26 or Claim 27 in which the flexible plastics film applied in the film application zone is a polyester film.

29. A method of producing laminated glass as claimed in claim 1 or claim 26, said method being substantially as hereinbefore described with reference to the accompanying drawings.

30. A method of producing laminated glass as claimed in any one of claims 1, 26 and 29, said method being substantially as hereinbefore described with reference to any one of the Examples.

31. A continuous method of producing a laminated safety glass as claimed in claim 19, said method being substantially as hereinbefore described with reference to the accompanying drawings.

32. A continuous method of producing a laminated safety glass as claimed in any one of claims 19 and 31, said method being substantially as hereinbefore described with reference to any one of the Examples.

33. Laminated glass when produced by a method as claimed in any one of the preceding claims.

34. Laminated glass as claimed in claim 33 being, as the case may be, laminated safety glass or a heat-reflective laminated glass or a heat-reflective laminated safety glass.