EP3030419A1

EP3030419A1 - Functionalised layered structure

Info

Publication number: EP3030419A1
Application number: EP14747073.6A
Authority: EP
Inventors: Jeanne MARCHAL; Montserrat BURGOS
Original assignee: Essilor International Compagnie Generale dOptique SA
Current assignee: EssilorLuxottica SA
Priority date: 2013-08-05
Filing date: 2014-07-01
Publication date: 2016-06-15
Also published as: US20160216425A1; CN105473330A; CN105473330B; FR3009234B1; FR3009234A1; KR20160040570A; JP2016527567A; WO2015018992A1

Abstract

The invention relates to a functionalised layered structure (2, 3, 20, 30) including: a first element that is a first single-layer or multi-layer functional film (2A, 4); at least one second element selected among a second functional film (2B) and a basic optical element (200, 300); at least one first pressure-sensitive adhesive layer (5A, 5B, 5) placed in contact with at least one surface of said first element and at least one surface of said second element. According to the invention, the surfaces of said first and second element, which are intended for being placed in contact with said adhesive layer, are subjected to a surface treatment prior to being placed in contact, such that the decrease between the peel force when dry and the peel force when wet is no higher than at least 35 %, inclusive.

Description

FUNCTIONALIZED LAYER STRUCTURE

The invention relates to a functionalized layered structure. It also relates to a functionalized layer structure comprising one or more functionalized films, associated or not with a basic optical element. The basic optical element may be, in particular, an ophthalmic lens. The invention is particularly advantageous in the case where the functionalized layer structure has a polarization functionality.

It is known to postpone, that is to say to assemble by bonding in particular, an optical quality polarizing film on the optical surface of a base lens to produce a polarized ophthalmic lens. This polarizing film has the function of eliminating parasitic reflections from the field of view which come from flat or quasi-flat horizontal surfaces, for example, such as a body of water, thus allowing a reduction of glare and an improvement. contrast for the wearer of the polarizing ophthalmic lenses.

These polarizing films are generally based on polyvinyl alcohol (PVA) or polyethylene terephthalate (PET). The (PVA) films are generally interposed between two protective films which are in particular based on cellulose triacetate (TAC) or polycarbonate (PC), or cycloolefin copolymer (COC). This protective film makes it possible to protect the polarizing film against external mechanical stresses when it is assembled with the basic optical element or finished glass, for example by involuntary tearing, scratching or diffusion of a foreign substance into the material. polarizing film. In addition, the protective film facilitates handling during the manufacturing cycle of the polarizing optical element. In the case of PVA, these protective films also make it possible to protect the latter against external aggression, the PVA having in particular a hygroscopic behavior.

A layer of PVA-based adhesive is interposed between the polarizing film and the protective film (s) to ensure the cohesion of this film. assembly. FIG. 1A illustrates a layered structure 1 comprising a polarizing film 4 according to the prior art, composed of a TAC 2A protective film, a PVA-based adhesive layer 7A, a PVA polarization film 4, a second layer of glue 7B and a second TAC 2B protective film. Figure 1B shows an assembly between the layered structure 1 of the prior art and a basic optical element 100 for producing a polarizing optical element. One of the faces of the polarizing layer structure 1, corresponding to the free face of one of the two protective films 2B, is bonded to the optical surface of the base optical element 100 by means of a layer of adhesive 101.

The polarizing basic optical element can then be varnished and then cut off so that its contour is adapted to the shape of the frame that receives it. The varnishing step may comprise surface preparations in the presence of water. The peripheral machining step can implement a standard method comprising at least one grinding step in which the lens is subjected to mechanical stresses in the presence of water. The polarizing layer structure as described above does not support such conditions (surface preparation, machining) which generally results in detachments at the interfaces of the layers. Indeed, the PVA-based glue which gives a good adhesion between the polarizing film and the protective films is unfortunately soluble in water and the assembly TAC // glue // PVA / glue // film separates most of time during the stages comprising water, such as the steps of preparation of surfaces before varnish, or following a mechanical effort in the presence of water (clipping).

An object of the present invention is therefore to provide a functionalized layer structure comprising at least one functionalized film, which can be implemented simply, while giving the structure a strong and durable adhesion during the successive stages of manufacture of the optical element, and especially the ophthalmic lens, especially when using post-treatment in the presence of water, (example: surface preparation, varnish, ophthalmic lens trimming). For this, the invention proposes a functionalized layer structure comprising

a first element representing a first monolayer or multilayer functional film;

at least one second element chosen from a second functional film and a basic optical element;

at least a first layer of pressure-sensitive adhesive placed in contact with at least one surface of said first element and at least one surface of said second element. According to the invention, the surfaces of said first element and second element intended to be brought into contact with said at least one layer of adhesive are subjected, prior to contacting, to a surface treatment so that the decrease between the peel force in dry condition and the peel force in wet condition is at least 35% or less inclusive.

According to the invention, the surfaces of said first element and second element having been subjected to a surface treatment have a surface energy of at least 60 mN / m.

According to the invention, the surface treatment is carried out a plasma treatment in inert nitrogen atmosphere, with a dosage of 40 to 100 W.min / m ^2.

According to the invention, the surface treatment is a corona treatment carried out in ambient air, with a dosage of 40 to 50 W.min / m ^2.

According to the invention, the first element represents a multilayer functional film, in which at least two layers are assembled by means of a layer of pressure-sensitive adhesive, the surfaces of the said at least two layers are subjected, prior to their assembly. to a surface treatment.

Preferably, the first element represents a functional film comprising at least one functionality chosen from among hue, polarization, photochromic, electrochromic, shockproof, anti-abrasion, antistatic, antireflection, anti-fouling, antifog, anti-rain, spectral filter on a band of determined wavelength, for example a blue light filter.

According to a preferred embodiment of the invention, the first element is a polarizing multilayer film comprising at least two films, respectively representing a polarizing film and a protective film. The polarizing film and the protective film are then assembled by means of a first layer of pressure-sensitive adhesive.

According to one embodiment of the invention, the second element is a basic optical element.

According to one embodiment of the invention, the second element is a second functional film such as a protective film. According to another embodiment of the invention, the structure further comprises a second second element representing a basic optical element, said second second element being brought into contact with the first second element, by means of a second layer of adhesive. According to the invention, this second adhesive layer is a layer of pressure-sensitive adhesive as defined above or an adhesive comprising at least one layer of adhesive material chosen from a layer of latex and a layer of adhesive material hot melt (HMA).

Preferably, said second adhesive layer is a pressure-sensitive adhesive layer. Particularly preferably, said second adhesive layer, selected as a pressure-sensitive adhesive layer, is further selected to be identical to said first pressure-sensitive adhesive layer, i.e. to say of the same chemical composition.

According to a preferred embodiment of the invention, the structure defining a polarization functionality comprises: a first element representing a protective film and a polarizing film,

a second element comprising a protective film;

a pressure-sensitive adhesive layer interposed between said films;

the surfaces of said first element and second element intended to be brought into contact with said adhesive layer being subjected, prior to contacting, to a surface treatment so that the decrease between the peel force in dry condition and the wet coat peel strength is at least 35% or less inclusive.

In this structure, the protective film prevents the polarizing film from being degraded and facilitates the manipulation of the polarizing structure. This makes it possible to better preserve the polarizing film when the latter is not yet applied against a basic optical element or when it is applied to the optical element when the glass is worn.

This protective film may be based on cellulose triacetate (TAC), cellulose acetate butyrate (CAB), polyethylene terephthalate (PET), polycarbonate, polyamide, cycloolefin copolymer (COC) or cycloolefin polymer (COP).

In the rest of the description, this layered structure comprising a polarizing film is also called a polarizing structure.

According to the invention, the use of pressure-sensitive adhesive material or PSA "Pressure Sensitive Adhesive" for bonding the PVA polarizing film with a TAC protective film and plasma or corona treatment is particularly advantageous compared to a conventional structure because it makes it possible to produce the polarizing structure in a simple manner while preserving the polarization quality of the polarizing film. Furthermore, it is remarkable that the specific combination of this adhesive material with a plasma-like surface treatment with a well-adjusted dosage of the surface energies of the films makes it possible to create strong bonds at the interfaces of the films and to guarantee strong cohesion. within the structure, and that cohesion is preserved even in the presence of water. The inventors have found that it is necessary to maximize the surface energy of the films, so that there is effective cooperation between the surface treatment and the adhesive material (PSA) interposed between the treated surfaces. They have found that this cooperation is effective when the polarizing structure has a decrease between the peel force in dry condition and the wet peel force of less than 35%.

This new polarizing structure makes it possible to avoid the phenomenon of separation between the polarizing film and the protective film during the trimming of a polarizing optical element provided with such a structure as well as during the surface preparation steps for varnish deposit.

The use of pressure-sensitive adhesive does not require the use of ultraviolet radiation or intensive heating to achieve permanent bonding. Thus the polarizing film is not altered or degraded by such irradiation or heating.

Preferably, the polarizing film has a treated surface energy of at least 56 mN / m 2 and the protective film has a surface energy when treated of at least 46 mN / m 2.

According to an alternative form of the invention, the polarizing structure comprises a single protective film disposed on one side of the polarizing film, the face of the polarizing film opposite to said protective film being covered by a conditioning film or not.

Several pressure-sensitive adhesives can be used to assemble the polarizing structure. The pressure-sensitive adhesive material is preferably a polyacrylate-based compound.

Preferably, the pressure-sensitive adhesive layer has a thickness of between 5 μιτι and 150μηη, preferably between 10 and 50 μιτι in order to ensure effective bonding while maintaining a uniform thickness.

Preferably, the polarizing film is based on polyvinyl alcohol (PVA), with a thickness typically between 20 βί δθμηη. According to an alternative form, it may be based on polyethylene terephthalate or PET with a thickness typically between 15 and 100 μιτι. The method of producing a polarizing structure as described above comprises the following steps:

a) obtaining a polarizing film;

- b) obtain a protective film and arrange it on each side of the polarizing film;

- c) interpose a layer of pressure-sensitive adhesive between the films;

- d) press the films together so as to obtain a permanent assembly.

This method further comprises an additional step before step c) in which the surfaces of said films intended to be brought into contact with said pressure-sensitive adhesive layer are subjected, prior to contact, to a surface treatment so that that the decrease between the peel force in dry condition and the peel strength in wet condition is less than 35%.

When the pressure-sensitive adhesive layer is disposed between two peelable packaging films, step c) comprises the following steps:

d) peeling one of the two peelable packaging films to expose one side of the pressure-sensitive adhesive layer;

c2) pressing the uncovered face of the layer of adhesive material on the treated side of the polarizing film, through the other film of conditioning said layer of adhesive material;

c3) peeling the other conditioning film so as to expose the other side of the layer of adhesive material, and

d) pressing the protective film on said uncovered face of the adhesive layer, with the treated side of the protective film facing the layer of adhesive material.

When the adhesive material is in liquid form, step c) is carried out by a centrifugation, coating, dipping or other deposition method. According to the invention, the structure can also define a polarizing ophthalmic lens comprising:

a first element representing a protective film and a polarizing film,

a second element representing a protective film;

a second second element representing a basic optical element;

a first pressure-sensitive adhesive layer interposed between said films,

a second adhesive layer interposed between the protective film and the basic optical element.

According to the invention, the surfaces of said films intended to be brought into contact with said first layer of adhesive are subjected, prior to contacting, to a surface treatment so that the decrease between the peel force in dry condition and the wet coat peel strength is at least 35% or less inclusive.

According to a preferred form of the invention, the second adhesive layer has a three-layer structure comprising a layer of hot melt adhesive material (HMA) interposed between two layers of latex. Such an adhesive structure is described in WO201 1/053329.

Such an ophthalmic lens may further comprise at least one functional film disposed on the outer face of the protective film, on one side of the polarizing film opposite to the basic optical element. Such a film can give the optical element additional functions, such as suppression of light reflections, protection against shocks or scratches, protection against dirt, fogging or tint These films can be arranged easily on the protective film (TAC).

Other features and advantages of the present invention will become apparent in the following description of nonlimiting exemplary embodiments, with reference to the appended drawings, in which:

FIGS. 1A and 1B respectively represent a sectional view of a layered structure comprising a polarizing film according to the prior art and that of a polarizing optical element comprising such a structure;

Figures 2A and 2B show sectional views of two polarizing structures according to the two embodiments of the invention;

Figures 3A and 3B show sectional views of a polarizing optical element comprising polarizing structures according to the two embodiments of the invention.

The examples above define a polarizing structure.

According to Figure 2A, a polarizing film 4 is interposed between two protective films 2A, 2B. This polarizing film 4 may consist mainly of polyvinyl alcohol, or PVA. It can have a thickness of between 20 and 80 μιτι. The protective films may have a thickness of between 40 μιτι and 200 μιτι.

To ensure the cohesion of this assembly, a layer of pressure-sensitive adhesive material 5A, 5B is interposed respectively between the first protective film 2A and the polarizing film 4 as well as between the second protective film 2B and the polarizing film 4 This layer of adhesive material may be polyacrylate, and has a thickness of 5μηη to 150μηη. It ensures a permanent maintenance of the protective film on the polarizing film.

According to the invention, the surfaces of the films 4, 2A, 2B which are intended to be brought into contact with the adhesive material layer 5A, 5B have been subjected to a plasma treatment.

This surface treatment makes it possible to maximize the surface energy of the films that will be in contact with the adhesive material and to maximize the adhesion of the films. By "maximizing film adhesion" is meant the determination of the maximum surface energy that achieves maximum film peel strength under dry conditions.

Surprisingly, this cooperation between the pressure-sensitive adhesive material and the surface treatment makes it possible to create strong bonds at the interfaces of the films and to guarantee a strong cohesion within the structure even in a wet condition. For that, all following conditions must be fulfilled:

- the surface energies must be maximum

- the peel strength in dry condition must be maximum

- the difference between the peel force in dry condition and the peel strength in wet condition must be at least 35% or less.

Unlike a conventional polarizing structure, this new structure allows the manufacture of a glass (varnish, trimming ...) in the presence of water without inducing separation defects between the films in the polarizing structure.

In the polarizing structure 3 shown in FIG. 2B, one of the faces of the polarizing film 4 is covered with a protective film 2A. The opposite side of the polarizing film is covered or not with a conditioning film 6 specific to the polarizing film (called "liner"). A layer of adhesive material 5 is interposed between the polarizing film 4 and the protective film 2. In this way, the two faces of the polarizing film are protected on one side by the protective film 2 and on the other by a film conditioning 6.

A first method of producing a polarizing structure according to the invention illustrated in FIG. 2A is now described.

According to a first embodiment of the invention, the pressure-sensitive adhesive material layer 5A, 5B, the polarizing film 4 and the protective film 2A, 2B are initially each in the form of a continuous film sandwiched between two laminating films (called "liner" in English) or without liner.

Before interposing the layer of adhesive material 5A, 5B between the polarizing film 4 and the protective film 2A, 2B, the three films 4, 2A, 2B are subjected to a plasma treatment separately or simultaneously. To make this plasma or corona, if there is a conditioning film, it is removed beforehand. The treated face is intended to be subsequently brought into contact with the layer of adhesive material.

The method for producing the polarizing structure comprises the following steps :

a) peeling one of the two conditioning films of the polarizing film 4 so as to discover one side of the polarizing film,

b) peeling one of the two conditioning films of the protective film 2A so as to discover one side of the protective film 2A,

b1) a plasma treatment is applied to these two exposed faces,

c) peeling one of the two conditioning films from the layer of adhesive material and applying this layer against the plasma-treated side of the protective film through the conditioning film of the layer of adhesive material

d) peeling the second conditioning film from the layer of adhesive material and applying the protective film + adhesive material stack against the plasma-treated side of the polarizing film.

Steps a) to d) thus allow the realization of the polarizing structure comprising a single protective film (FIG 2B). In the context of producing the polarizing structure of FIG. 2A, steps a) to d) are repeated so as to add the second TAC 2B protective film.

According to another embodiment of the invention, the adhesive material being conditioned in the form of a liquid, step c) is carried out by a technique known to those skilled in the art such as centrifugation (spin-coating). in English), coating, dipping or otherwise on one side of the protective film or on one side of the polarizing film, the two faces being pretreated with plasma. This embodiment makes it possible to control the thickness of the layer of adhesive material and to optimize it.

A functionalized layer structure comprising such a polarizing structure and a basic optical element, is now described above.

A functionalized layer structure comprises two main components: a basic optical element represented by a base lens, and a first element comprising the polarizing structure comprising at least one functional film. The base lens is obtained from a Semi-finished lens with two surfaces that are opposite to each other. One of these two surfaces, called the first optical surface, is made directly with a final curvature during the step of manufacturing the semi-finished lens. In general, this first optical surface may be the anterior convex surface of the base lens in the final ophthalmic lens, and is determined by the shape of the mold, the molding technique or the injection technique. The other surface of the semi-finished lens is temporary and intended to be subsequently scaled to the optical correction of the lens wearer.

The semi-finished or finished lens material may be a thermosetting material with a reflection index of between 1.5 and 1.7. It can also be a thermoplastic material with a reflection index of between 1.5 and 1.6.

The polarizing structure as described above and illustrated in Figures 2A and 2B may be thermoformed so that the shape of its curvature is compatible with one of the optical surfaces of the semi-finished or finished lens. This method of preforming the polarizing structure is well known. This polarizing structure has a technical advantage over polarizing structures known by the presence of the two protective films, to facilitate the thermoforming of the polarizing structure.

The polarizing structure is then applied by a lamination process to the first optical surface of the semi-finished or finished lens. A layered structure of adhesive material which may be an adhesive material (PSA) or a latex // HMA // latex trilayer is interposed between the polarizing structure and the base optical element to achieve permanent adhesion.

In the remainder of the description this layered structure of adhesive material interposed between the polarizing structure and the base lens is also called adhesive structure.

According to an advantageous embodiment of the invention, this adhesive structure can consist of a monolayer of material pressure sensitive adhesive (PSA). This layer is particularly advantageous because it makes it possible to apply the polarizing structure simply to the optical surface of the basic optical element while preserving the dioptric properties of the optical element. In order to increase the adhesion force between the polarizing structure and the optical element, before interposing the layer of pressure-sensitive material between the polarizing structure and the optical surface of the basic optical element, the surfaces which are intended to be brought into contact with the layer of pressure-sensitive adhesive material have also been subjected to a plasma or corona surface treatment.

We now describe a method of assembly between a polarizing optical element and a polarizing structure according to the invention as described above and illustrated in Figure 3A.

The method of producing the polarizing optical element shown in FIG. 3A comprises the following steps:

a) peel one of the two conditioning films, if any, of the protective film, the polarizing structure 2

b) a plasma or corona treatment is applied on this uncovered face and on the convex or concave face of the basic optical element; c) peeling one of the two conditioning films from the layer of adhesive material 201 and applying this layer against the plasma-treated face of the base optical element 200 through the conditioning film of the layer of adhesive material

d) peeling the second conditioning film from the layer of adhesive material 201 and pressing the polarizing structure 2 against the convex or concave face of the base optical element so as to obtain a final assembly, the plasma-treated face of the polarizing structure 2 facing the exposed face of the layer of adhesive material 201. Preferably, the polarizing structure is deposited on the convex face of the basic optical element.

Preferably the thickness of this layer of adhesive material 201 is between 5 and 150μηη so as not to alter the power nominal of the optical element.

In a variant of the embodiment of the invention, the adhesive structure is first pressed against the exposed and plasma-treated face of the polarizing structure 2.

Before step a), the polarizing structure 2 is preformed before being pressed against the convex or concave face of the basic optical element. This preforming can be done in different ways. It comprises in particular a thermoforming step during which it is heated before being deformed. The thermoforming temperature is limited so as not to alter the integrity of the polarizing film and so that it can easily fit the shape of the convex face. or concave of the basic optical element. In the case where the adhesive structure is first pressed against the polarizing structure, the polarizing structure is preformed with the adhesive structure before the assembly is pressed against the convex or concave face of the basic optical element through the polarizing structure

To apply the polarizing structure provided with a single protective film 3 on the basic optical element, the procedure is similar: a) the conditioning film 6 of the polarizing film of the polarizing structure 3 is peeled so as to reveal a face of the polarizing film, the other side being covered by a protective film 2;

b) a plasma treatment is applied on this uncovered face and on the convex or concave face of the base optical element 300;

c) peeling one of the two conditioning films from the layer of adhesive material 301 and applying this layer against the plasma or corona-treated surface of the base optical element 300 through the film of conditioning the layer of material adhesive

d) peeling the second conditioning film from the adhesive material layer 301 and pressing the polarizing structure 3 against the convex or concave face of the base optical element 300 so as to obtain a final assembly with the plasma-treated face of the polarizing structure 3 facing the exposed face of the adhesive material 301.

These two transfer methods concern the case where the Pressure-sensitive adhesive material is packaged as a film. Of course, the polarizing optical element can also be realized when the adhesive material is in the form of a liquid.

In another embodiment of the invention, the adhesive structure 201, 301 may be a stack of three-layer Latex / Hot Melt Adhesive Material (HMA) / Latex. The method of transferring the polarizing structure no longer requires the plasma treatment step. Deposition of such an adhesive structure on the convex face of the base optical element 200, 300 is known. It consists of a set of deposition steps by spin-coating and heating. Such an adhesive structure is described in WO 201 1/053329.

In the polarizing optical elements thus obtained 20, 30, the polarizing films are protected on one side by a protective film and on the other side by the optical base element, against any dirt or scratch that may occur during the use of the optical element.

In the case where the polarizing structure is applied on the convex face of the optical element, functional coatings may be placed on the protective film on the outer face thereof, namely the face furthest from the eyes of the optical element. carrier of ophthalmic lenses. These coatings thus make it possible to confer, in addition to the optical element, an anti-shock function, an antireflection function, an anti-abrasion, anti-fouling, anti-fogging or colored function.

Protocol for measuring the peel strength

The peel test consists of rolling a 25 x 70 mm strip of pressure-sensitive adhesive material onto a protective film strip. This tape (protective film + adhesive material) is glued on a plane support on which is fixed beforehand a polarizing film. This test makes it possible to test the adhesion between the polarizing film and the protective film. The glass is conditioned at least 24 h (at 23 ° C ± 3 ° C, 50% RH ± 10%) before peeling. The film is peeled at a 90 ° angle at a speed of 2.54 cm / min. At half of the test, a quantity of water is added to the interface to measure the peel force in a humid environment. The force is expressed in N / 25mm.

Software continuously measures peel force as a function of displacement. This force is averaged over a length of 10 mm for dry peeling and 15 mm for wet peeling.

Surface energy measurement protocol

In order to measure the surface tension of the polarizing and protective films, calibrated inks are applied on the surface of the untreated films and then a second time on the treated material (plasma or corona). If ^the applied ink is stable, the substrate surface voltage is at least the value of the test ink.

If the ink is contracted, is repeated ^the test with an ink showing a lower surface tension. The surface energy of the material is equal to the value of the last ink tested which showed good wetting for several seconds.

Surface treatment protocol in the examples below The protective films and the polarizing film are subjected to an oxidizing plasma (vacuum or atmospheric plasma), or a corona (atmospheric plasma), just before the films are assembled together. with the adhesive. The plasma parameters used in the examples below are as follows: Vacuum plasma machine reference: M4L, pressure 376 mTorr, gas flow 200 sccm O2, Power 390 W, exposure time 30 seconds.

Examples of comparison:

Samples 1 - 6:

These samples are all composed of a TAC // PVA // TAC layered structure, assembled with a layer of adhesive material sold by 3M under the reference 8146-1. This layer of adhesive material has a thickness of 25 μιτι. TAC films and PVA film are provided by FUJI and ONBITT respectively

This polarizing layer structure is then laminated on an optical element marketed under the name Ormix basic index 1 .6. The lamination process is described in WO / 2012/078152.

For each of the samples except sample 1, the treated surfaces before assembly are explained in the "surface treatment" column.

The samples are then washed, varnished and finally cut with a clipping machine Kappa (trade name)

Once cut off, the samples are inspected to determine if there are cosmetic defects such as the separation of films in the polarizing structure. When the stack has defects, this is indicated in the column "Glass production" of the table, by a cross. When the trimming has no defect, this is indicated in this same column by "ok".

Samples 1 -6 (Table 1)

Table 1

Force Manufacturing% Force Treatment No

Sample surface peel surface peeled between glass

TAC // PVA dry wet peeling (Varnish,

(mN / m) (N / 25mm) (N / 25mm) wet Clipping)

TAC / PSA TAC / PSA and

PVA PVA peeling

dried up

1 44/40 No 1 1 4.7 57% X

treatment

2 44/58 On PVA film 1 1.5 3.9 66% X

3 50/40 On film TAC 10.4 9.5 9% X 4 50/58 On film TAC + 16.6 15.5 7% Ok

On PVA film

5 44/40 On the adhesive 12.7 4 69% X

6 44/58 On film PVA + 12.6 4 68% X

On the adhesive

In Table 1, the polarizing structure of the sample 1 was carried out without surface treatment on the TAC and PVA films before assembly of the layers, in the sample 2, only the PVA film was treated and in the sample 3 only the TAC film has been processed. In these configurations, the surface energy is not maximum, the peel force decreases when passing from a test performed in a dry condition to a test performed in a wet condition drastically. For samples 1, 2, 5 and 6, this decrease is between 57% and 69%. After subjecting these samples to the different glass manufacturing steps, the stack exhibits delamination type defects, namely a separation between the films in the polarizing structure. For sample 3, the surface treatment is applied only to the TAC film face, ie the protective film which has a maximum surface energy of 50mN / m. The PVA film which has not been subjected to a surface treatment then has a low surface energy, 40 mN / m. Although the decrease between the dry peel strength and the wet peel force is small, on the order of 9%, this sample has delamination defects after the clipping step. This result shows that it is necessary to treat both sides of the films to be contacted with the adhesive material to have effective cooperation between the treated films and the adhesive material and a peel force in the maximum dry condition. In Table 1, this peel force in dry condition is 16.6 N / 25mm (Sample # 4).

The only configuration that works is sample 4 in which all the TAC and PVA film interfaces have been processed before the polarizing structure is made. It does not delaminate during the different stages of glass manufacture. The surface energy is then maximum, the The treated surfaces of the TAC and PVA films have 50 mN / m and 58 mN / m, respectively. This very good performance results in a very small decrease between the peel force in dry conditions and the peel force in wet conditions, it is of the order of 7%.

Samples 7-12 (Table 2)

The samples are made under the same conditions as samples 1 to 6.

The polarizing structure TAC // PVA // TAC, treated on all the film interfaces before assembly, assembled with a 3M adhesive ref. 8146-X, (of suitable chemical composition) has different thicknesses of 5μηη (sample 7), 15μηη (sample 8), 25μηη (sample 9), 50μηη (sample 10), 75μηη (sample 1 1), 150μηη (sample 12). For all these samples, the plasma treatment is applied to the TAC and PVA films so that their surface energy is maximum, equal to 50 and 58 mN / m respectively.

Table 2

This table makes it possible to show that the samples pass the different stages of manufacture of the glass (wet conditions) whatever the thicknesses of adhesive. These test results show that when a pressure sensitive adhesive material having the right physical and chemical characteristics cooperates with a surface treatment (plasma or corona) which maximizes the surface energies, the decrease between the peel force in dry condition and the peel strength in wet condition is very low, it is between 5% and 12%. For thin layers, ie less than 25μηη, it is at most 35% and of the order of 10% for adhesives exceeding the thickness of 25μηη.

The polarizing structure then presents no defects

(separation, bubbles, edge, deformations, ...) after the glass manufacturing steps.

Samples 13 - 16 (Table 3)

Samples 13 to 16 are made under the same conditions as the above samples. The only difference lies in the nature of the pressure sensitive adhesive material. Table 3

For these test samples, the polarizing structure is assembled based on an adhesive material sold by Panac, reference PD S1, of different thicknesses: from 5μηη (sample 13), 10μηη (sample 14), 15μηη (sample 15), 25μηη (sample 16). This table shows that the system does not work with a pressure sensitive adhesive whose chemical composition is inadequate and therefore does not cooperate with the plasma treatment even if the surface energy is maximum. This non-cooperation between the adhesive material and the plasma treatment therefore induces a significant difference between the peel strength in dry condition and the peel force in wet condition. It varies between 77% and 89%, regardless of the thickness of the adhesive. The samples have defects after the different glass manufacturing steps.

Claims

1. A functionalized layered structure (2, 3, 20, 30) comprising a first element representing a first monolayer or multilayer functional film (2A, 4);

at least one second element chosen from a second functional film (2B) and a basic optical element (200, 300);

at least a first layer of pressure-sensitive adhesive (5A, 5B, 5) brought into contact with at least one surface of said first element and at least one surface of said second element, characterized in that

the surfaces of said first element and second element intended to be brought into contact with said at least one layer of adhesive, are subjected, prior to contacting, to a surface treatment chosen from a plasma treatment carried out in an atmosphere of inert nitrogen with a dosage between 40 and 100 W. min / m ² and a corona treatment carried out in the ambient air with a dosage of between 40 and 50 W. min / m ² , so that the decrease between the force in dry condition and the peel strength in wet condition is at least less than or equal to 35% inclusive.

2. Structure according to claim 1, characterized in that the first element represents a multilayer functional film, wherein at least two layers are assembled by means of a layer of pressure-sensitive adhesive, the surfaces of said at least two layers. are subjected, prior to their assembly to a surface treatment.

3. Structure according to claim 1, characterized in that the first element represents a functional film comprising at least one functionality selected from hue, polarization, photochromic, electrochromic, shockproof, anti-abrasion, antistatic, antireflection, antifouling, antifog, anti rain and spectral filter on a determined wavelength band.

4. Structure according to claim 2, characterized in that the first element is a polarizing multilayer film comprising at least two films, respectively representing a polarizing film (4) and a protective film (2A) and in that the polarizing film ( 4) and the protective film (2A) are assembled by means of a layer of pressure-sensitive adhesive.

5. Structure according to one of claims 1 to 4, characterized in that the second element is a basic optical element (200, 300).

6. Structure according to one of claims 1 to 4, characterized in that the second element is a second functional film (2B).

7. Structure according to claim 6, characterized in that it further comprises a second second element representing a basic optical element (200, 300) said second being brought into contact with the first second element, by means of a second adhesive layer (201, 301).

8. Structure according to claim 7, characterized in that said second layer of adhesive (201, 301) is a layer of pressure-sensitive adhesive defined according to claim 1 or an adhesive comprising at least one layer of selected adhesive material among a layer of latex and a layer of hot melt adhesive material (HMA).

9. Structure according to one of claims 1 to 8, characterized in that the surfaces of said first element and second element having been subjected to a surface treatment have a surface energy of at least 60 mN / m.

10. Structure according to claim 4, characterized in that the polarizing film has a surface energy when treated of at least 56 mN / m and the protective film has a surface energy when treated of at least 46 mN / m.

1 1. Structure according to one of claims 1 to 10, characterized in that said first layer of pressure sensitive adhesive (5A, 5B, 5) and the second layer of adhesive (201, 301) have a thickness of between μιτι and 150μηη.

12. Structure according to one of claims 7 to 9 or 1 1, characterized in that said first layer of pressure-sensitive adhesive (5A, 5B, 5), and said second layer of adhesive (201, 301) are the same.

13. Structure according to one of claims 1 to 12, characterized in that the pressure-sensitive adhesive material is selected from a compound based on polyacrylate.

14. Structure according to one of claims 1 to 13, characterized in that the polarizing film is based on polyvinyl alcohol (PVA) or polyethylene terephthalate (PET).

15. Structure according to one of claims 1 to 14, characterized in that the protective film is based on cellulose triacetate, cellulose acetate butyrate, polyethylene terephatalate, polycarbonate, polyamide, cyclo copolymer -olefin (COC) or cycloolefin polymer (COP).

16. Structure according to one of claims 1 to 15, characterized in that it comprises:

a first element representing a protective film (2A) and a polarizing film (4),

a second element comprising a protective film (2B); a layer of pressure-sensitive adhesive (5A, 5B) interposed between said films, characterized in that the surfaces of said first element and second element intended to be brought into contact with said adhesive layer are subjected, prior to the contacting, to a surface treatment so that the decrease between the peel force in dry condition and the peel strength in wet condition is at least less than or equal to 35% inclusive.

17. Structure according to one of claims 1 to 15, characterized in that it defines a polarizing ophthalmic lens.

18. Structure according to claim 17, characterized in that it comprises:

a first element representing a first protective film (2A) and a polarizing film (4),

a second element representing a second protective film

(2B);

a second second element representing a basic optical element (200);

a first layer of pressure-sensitive adhesive (5A, 5B) interposed between said films,

a second adhesive layer (201) interposed between the second protective film (2B) and the basic optical element (200), characterized in that the surfaces of said films (2A, 2B, 4) intended to be in contact with said first adhesive layer (5A, 5B) are subjected, prior to contacting, to a surface treatment so that the decrease between the peel force in dry condition and the peel force in wet condition is at least 35% or less inclusive.