Process of forming multi-play laminates

Claim 1

A process of forming a multi-ply laminate which comprises at least one ply or glass (1) and at least one ply (2) of thermoplastics material, the ply of thermoplastics material forming a transparent outer ply of the laminate, such process comprising assembling the plies (1, 2) of the laminate to create at least one inter-ply space between mutually adjacent plies, contacting the outer ply with a moulding plate (3) to form an assembly, said assembly having main faces, degassing the inter-ply space and subjecting the plies to bonding conditions including environmental laminating pressure distributed over the outside of the said thermoplastics outer ply (2) by the moulding plate (3), characterised by the steps of: enveloping at least the edges of the assembled laminate plies (1, 2) and moulding plate (3) by means (4) defining therewith an edge space (5) in communication with the inter-ply space, reducing the pressure (P5) within said edge space (5) to commence degassing of the assembly, and heating the assembly (curve T) while the main faces of the assembly are subjected to at least atmospheric environmental pressure (P6) subsequent to said step of reducing the edge space pressure, and while the assembly is subjected to environmental laminating pressure, raising said edge space pressure (P5) to reduce or eliminate any difference between said edge space pressure (P5) and said environmental laminating pressure (P6) before the assembly reaches its maximum temperature (T) and not later than the time when the assembly reaches a temperature at which effective adherence commences between the laminate plies, corresponding to a peel strength of 25 g/cm between the laminates plies, and continuing to heat the assembly and maintaining environmental laminating pressure (P6) to complete bonding of the laminate plies.