Method of producing a polarizing optical element
View Patent ↗A polarizing optical element is produced by firstly forming a polarizing multilayer structure ( 30 ) on a support ( 31 ). The structure comprises an orienting layer and a polarizing layer having dichroic compounds, the dichroic compounds being oriented by the orienting layer. The multilayer structure is then pressed against one surface of the optical element ( 40 ) through the support, with a portion of adhesive placed between the structure and the optical element. The support ( 31 ) for the structure is then removed, leaving the structure ( 30 ) bonded to the optical element ( 40 ).
1. Method of producing a polarizing optical element by applying a multilayer structure to one surface of a base optical element, the structure comprising an orienting first layer and a polarizing second layer comprising liquid-crystal polymers and at least one dichroic dye, said dichroic dye having an angular orientation determined by the first layer, the method comprising the following steps:
a) producing the multilayer structure on a support;
b) placing the base optical element and the multilayer structure carried by the support between a first pressing device having a bearing surface and a second pressing device having an inflatable membrane, the multilayer structure facing the base optical element and a portion of an adhesive being placed between said structure and said base element;
c) pressing the multilayer structure against the surface of the base optical element by inflating the membrane of the second device and maintaining a fixed gap between the first and second pressing devices; and
d) releasing the optical element and removing the support so as to leave the multilayer structure bonded to the surface of said base optical element,
in which the first pressing device having the bearing surface includes another inflatable membrane, that forms said bearing surface, and in which step c) is carried out by inflating the membranes of the first and second pressing devices, and
wherein said polarizing second layer is undercured during steps b) and c).
2. Method according to claim 1 , which includes a step of supplementarily curing the polarizing second layer, carried out after step c).
3. Method according to claim 1 , in which the first layer comprises a network of polymers photooriented along a defined direction, and in which the second layer comprises a matrix of monomeric liquid crystals, said matrix being oriented by the first layer and fixing the orientation of the dichroic compounds.
4. Method according to claim 3 , in which step a) comprises the following substeps:
1) forming a first layer comprising photoorientable polymers on the support;
2) curing the first layer using a linearly polarized ultraviolet radiation so as to produce a network of polymers photooriented along a direction imposed by the direction of polarization of said incident UV radiation;
3) forming a second layer, comprising a mixture of at least one dichroic dye and at least one crosslinkable monomeric liquid crystal, on the first layer, said dye and said liquid crystal both being angularly oriented by the first layer; and
4) curing the liquid-crystal compounds of the second layer at least partly so as to fix the dichroic compounds in the angular orientation determined by the first layer.
5. Method according to claim 1 , in which the multilayer structure further includes at least a third layer selected from a UV radiation protection layer, an oxygen barrier layer, an abrasion-resistant layer, an impact-resistant layer, an antireflecting coating, an antistatic coating and an antisoiling coating, said third layer lying between the support on the one hand and said first and second layers on the other.
6. Method according to claim 1 , in which the portion of adhesive is initially placed on the multilayer structure in the form of a layer lying on the opposite side of said first and second layers from the support.
7. Method according to claim 6 , in which the adhesive layer is deposited on the multilayer structure by spin coating.
8. Method according to claim 1 , in which the portion of adhesive is initially deposited in the form of a layer on the optical element on its face intended to receive the multilayer structure.
9. Method according to claim 8 , in which the adhesive layer is deposited on the base optical element by spin-coating.
10. Method according to claim 1 , which further includes irradiating the adhesive portion, after step c), in order to harden said portion.
11. Method according to claim 10 , in which irradiating the adhesive portion is carried out between steps c) and d), through the first or second pressing device.
12. Method according to claim 1 , in which a peeling layer is placed between the support and the multilayer structure.
13. Method according to claim 12 , in which the peeling layer comprises a silicone-based surfactant compound.
14. Method according to claim 1 , in which the support has a shape substantially complementary to the surface of the base optical element, when said support and said element are positioned for step b).
15. Method according to claim 1 , in which the surface of the base optical element is convex.
16. Method according to claim 1 , in which the base optical element comprises an ophthalmic lens.
17. Method according to claim 16 , in which the ophthalmic lens has a refractive index of 1.60 or higher.
18. Method according to claim 1 , in which, in step b), the base optical element is placed on the side of said first pressing device and the multilayer structure is placed on the side of said second pressing device.
19. Method according to claim 1 , in which the bearing surface of the first pressing device comprises a resilient cushion.