FIELD OF INVENTION

The present invention relates to a method for bonding a first body to a second body, comprising the use of a curable adhesive composition.

BACKGROUND OF INVENTION

Disposable medical devices represent a significant percentage of the medical market worldwide. Billions of widely diverse disposable medical devices are assembled annually, including, for instance needles.

Many of these disposable medical devices require that two or more components be joined together through thermal or light curing of adhesive compositions. Drawbacks of the thermal curing of bonding agents usually result from the duration of the curing step (amounting to 15 to 45 minutes), and from the restrained choice of materials that could be used for the medical devices components. On the contrary, light curing of the bonding agent provides with a faster process - typically between 1 and 20 seconds - and thus presents a strong industrial interest. Light curing technologies have thus become the preferred joining method for assembling disposable medical devices. Nevertheless, light curing methods are difficult to implement owing to the necessity to dispense sufficient amounts of light over small and depth bonding-lines or bonding areas.

Whereas several curable compositions, and more specifically photo-initiators for bonding parts of disposable medical devices, are well described in the art, there is still an ongoing need for improved bonding solutions and methods. It indeed appears critical that the corresponding elements be assembled such as to prevent fluid, for instance a medicine or blood, from leaking, or for ensuring a good shear resistance. However, in the current curing method, free radicals created by the decomposition of the initiator can be scavenged by oxygen, thereby leading to an incomplete polymerization of the bonding agent. Further, typical materials used for preparing medical devices, such as polyethylene and polypropylene, are difficult-to-bond plastic that often require a surface treatment to achieve high pull strengths. Other bonding troubles also appear to arise from the use of conventional light-curing units, such as quartz-tungsten halogen lamp, xenon plasma-arc lamp and light emitting diode (LED): such light-curing units usually require to be placed on a very close proximity to the bonding agent, thereby strongly impacting the industrial yields and costs for producing the disposable medical assemblies. Research for developing new high-strength joining methods is thus ongoing.

The present inventors have surprisingly discovered a new method for bonding two bodies together through the implementation of an electromagnetic radiation for curing an adhesive composition comprising photo-initiators. The method of the present invention advantageously provides with a precise, efficient and cost effective method for fixedly joining the various parts of disposable medical devices, while facilitating the industrial process. This method further minimizes the possibility to generate unbound or lightly bound devices, in ensuring that the adhesive solution is cured over depth that could not be reached by methods known in the art. The resulting articles thus display advantageous and enhanced resistance to tearing and to fluid leaking.

WO 90/10254 discloses a method for polymerizing a composition comprising a photopolymerizable monomer and a photo-initiator system, wherein the said composition is subjected to an activating radiation, e.g. a laser beam, for inducing the polymerization. The disclosed method in particular comprises the use of photo-initiators selected in the group comprising eosin lactone, methylene violet, methylene blue, methylene green, ethyl eosin ester, eosin ester RB lactone, ethyl RB, RB peroxide, eosin peroxide or erythrosine Bd, and is thus carried out with visible light, the wavelength of which ranges from 600 nm to 1000 nm. US 2010/0028701 discloses a method for adhesively bonding two substrates SI and S2, comprising applying a free-radically curable composition comprising a photo-initiator to SI, irradiating the composition with an electromagnetic radiation for curing it, and contacting the applied composition with S2. This document in particular discloses the use of phosphine oxides, and more specifically of diphenyl(2,4,6- trimethylbenzoyl)phosphine oxide (TPO) as photo-initiators, as well as the use of electromagnetic radiations of wavelengths comprised between 230 nm and 400 nm.

WO 2013/026024 discloses a method for bonding two polycarbonate substrates covered with metallic layers through the use of an energy curable resin comprising a photo- initiator such as TPO. The disclosed method, aiming at producing optical digital recording disks, may in particular comprise the curing of the bonding composition with UV radiations.

SUMMARY

The present invention thus concerns a method for bonding a first body to a second body comprising: applying a curable adhesive composition comprising at least one monomer and at least one photo-initiator between a contact surface of the first body and a contact surface of the second body; and curing the said curable adhesive composition by applying thereon an electromagnetic radiation; wherein the said contact surfaces of said first body and said second body are substantially non-planar or a light source cannot be easily brought near or close to said surfaces, especially because of the complex geometry of the piece around the surfaces; wherein the said electromagnetic radiation has a wavelength which is sufficient for inducing the decomposition of said at least one photo-initiator into free radicals; and wherein at least one of the said first body or said second body does not substantially absorb the said electromagnetic radiation. In a particular embodiment, said electromagnetic radiation is a light emitted by a laser.

In a particular embodiment, said laser light has a wavelength of from 200 nm to 450 nm, preferably of from 350 nm to 420 nm, preferably of from 390 nm to 410 nm. In a preferred embodiment, said laser light has a wavelength of about 405 nm. In a particular embodiment, the duration of the curing step ranges from 0.1 to 50 seconds, preferably from 0.5 to 20 seconds, preferably from 1 to 5 seconds.

In a particular embodiment, the laser used in the method of the invention has a power ranging from 20 to 500 milliwatts, preferably from 100 to 450 milliwatts, preferably from 200 to 300 milliwatts and is preferably of about 300 milliwatts. In a particular embodiment, the at least one photo-initiator used in the method of the invention is selected in the group consisting of dl-2,3-diketo-l,7,7- trimethylnorcamphane, 1 -phenyl- 1,2-propanedione, diphenyl (2, 4, 6- trimethylbenzoyl)phosphine oxide and bis(2,6-dichlorobenzoyl)-(4- propylphenyl)phosphine oxide. In a preferred embodiment, the at least one photo- initiator is diphenyl(2, 4, 6 trimethylbenzoyl)phosphine oxide.

In a particular embodiment of the present invention, the at least one monomer of the adhesive composition is an acrylic -based monomer.

In a particular embodiment, the adhesive composition for use in the method of the invention is under liquid form. In a particular embodiment of the present invention, the said first body is a cannula and the said second body is a hub.

In a particular embodiment, the adhesive composition is deposited at the distal end of said hub and said cannula is inserted in the hub, before the curing step. In another embodiment, the cannula is inserted in the hub and said adhesive composition is deposited at the junction between said cannula and said hub, at the distal end of said hub, before the curing step. In a particular embodiment, the adhesive composition is dispensed in the space between said hub and said cannula. The present invention further concerns an article resulting from the bonding of a first body and of a second body by the method of the invention. In a particular embodiment, the said article is a syringe, a needle or a catheter comprising a cannula and a hub bound together according to the method of the invention.

DEFINITIONS

In the present invention, the following terms have the following meanings:

As used herein the singular forms "a", "an", and "the" include plural reference unless the context clearly dictates otherwise. - The term "about" is used herein to mean approximately, roughly, around, or in the region of. When the term "about" is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term "about" is used herein to modify a numerical value above and below the stated value by a variance of 20 percent, preferably of 5 percent.

DETAILED DESCRIPTION

Method

The present invention concerns a method for bonding a first body to a second body comprising: applying a curable adhesive composition comprising at least one monomer and at least one photo-initiator between a contact surface of the first body and a contact surface of the second body; and curing the said curable adhesive composition by applying thereon an electromagnetic radiation; wherein the said contact surfaces of said first body and said second body are substantially non-planar or a light source cannot be easily brought near or close to said surfaces; wherein the said electromagnetic radiation has a wavelength which is sufficient for inducing the decomposition of said at least one photo-initiator into free radicals; and wherein at least one of the said first body or said second body does not substantially absorb the said electromagnetic radiation. In a particular embodiment, said electromagnetic radiation is a light emitted by a laser.

As used in the present invention, the expression "curable adhesive composition" refers to a composition comprising at least one monomer, or a mixture of at least one monomer with at least one oligomer and/or polymer, and at least one photo-initiator.

As used herein, the term "monomer" means a molecule that may react chemically to another molecule of the same type to form a larger molecule, such as an oligomer or a polymer. Within the context of the invention, by "monomer", it is meant free-radically polymerizable monomer, i.e. a monomer that possesses the capacity to polymerize when subjected to free -radicals. Further, the term "oligomer" means a polymer formed by the chemical linking of two, three, or four monomers. The term "polymer", as used in the present invention, means a chemical assembly of monomers that are arranged in a simple repeating structure to form a larger molecule. Polymers may comprise up to millions linked monomers.

In a preferred embodiment, the adhesive composition of the invention is composed of at least one monomer before the curing step and is essentially composed of polymers after the curing step.

Preferably, the at least one monomer comprised in the curable adhesive composition for use in the method of the invention is such that the polymer mixture formed after curing of the composition is forming a strong physical bond between the said first body and the said second body. In a particular embodiment of the present invention, the at least one monomer of the curable adhesive composition is an acrylic -based monomer, or any material that one skilled in the art would find suitable. Further, in a particular embodiment, the uncured adhesive composition for use in the method of the invention is under a liquid or semi-liquid form. In a particular embodiment, the said uncured adhesive composition is under the form of a thick oil or a paste, rendering the composition easier to spread between the contact surfaces of the first and second bodies that are to be bonded.

In a preferred embodiment, the viscosity of the curable adhesive composition is as low as, for example, about 10000 mPa.s and therefore can be readily filled into the space between the contact surface of the first body and the contact surface of the second body.

By "at least one", it is meant that the curable adhesive composition of the invention may comprise one or more monomers, such as a mixture of two or several monomers, a mixture of one monomer and several oligomers and/or polymers or a mixture of several monomers and several oligomers and/or polymers. Similarly, the curable adhesive composition for use in the invention may comprise one or more photo-initiators.

By "photo-initiator", it is referred to substances that can produce free radicals and promote radical reactions, either naturally or under the stimulation of a physicochemical event such as, for instance, irradiation by an electromagnetic radiation (e.g., by exposure to a light). The free radicals formed by the decomposition of the photo- initiator are advantageously capable to initiate the polymerization of monomer molecules contained in the curable adhesive composition to yield a polymer.

More particularly, within the context of the present invention, the term "photo- initiator" refers to substances which, upon exposure to light of a proper intensity and spectral output, decompose to yield free radicals initiating polymerization of monomers placed in contact within a same composition. According to one embodiment, the at least one photo-initiator for use in the method of the invention is selected from phenylpropadione, monoacylphosphine oxide, bisacylphosphine oxide, diphenylphosphine oxide, camhorquinone, or mixture thereof. According to a preferred embodiment, the said photoinitiator is selected in the group consisting of dl-2,3-diketo- 1,7,7-trimethylnorcamphane, 1 -phenyl- 1,2-propanedione, diphenyl (2, 4, 6- trimethylbenzoyl)phosphine oxide and bis(2,6-dichlorobenzoyl)-(4- propylphenyl)phosphine oxide. In a preferred embodiment, the at least one photo- initiator is diphenyl(2, 4, 6 trimethylbenzoyl)phosphine oxide. This photo-initiator is available commercially, for example from the DAROCUR product line of Ciba Specialty Chemicals. In a further embodiment, the curable adhesive composition for use in the method of the invention may further comprise a reducing agent. Any suitable reducing agent may be used, depending on the monomer and on the photo-initiator selected for use in the method of the invention. In one embodiment, the reducing agent may be ethyl p- dimethylamino benzoate. The adhesive composition for use in the present invention may further contain any additional compound, such as a dye, a hardener, a smoother, etc., provided the fact that said additional compound does not prevent the curing of the composition, and the tight assembling of said first body with said second body.

Within the context of the present invention, by "curing", it is meant that the curable adhesive composition, when subjected to an electromagnetic radiation suitable for inducing the decomposition of the photo-initiator(s) contained therein, hardens as a result of monomer(s) polymerization.

In the method of the present invention, the curing step is performed in subjecting the curable adhesive composition to an electromagnetic radiation. By "electromagnetic radiation", it is meant a radiant form of energy, propagating through space via electromagnetic waves and/or particles (photons). As an electromagnetic wave, the electromagnetic radiation has both electric and magnetic field components, which oscillate in a fixed relationship to one another, perpendicular to each other and perpendicular to the direction of energy and wave propagation. Electromagnetic radiations in particular comprise radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

In a particular embodiment of the invention, the said electromagnetic radiation is a light emitted by a laser. By the term « laser » (for "light amplification by stimulated emission of radiation"), it is meant a light emitted through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Lasers notably differ from other light sources in that they emit light coherently, i.e. they can be launched into beams of very low divergence in order to concentrate their power at large distances, with a focus on very tiny spots. Owing to its generation by stimulated emission, laser light remains very similar to the input signal in terms of wavelength, phase, and polarization. As a matter of consequence, laser light displays only slightly different frequencies (wavelengths) and lasers are usually considered as being "single wavelengthed". A laser for use in the present invention is such that the wavelength of the emitted light effectively and precisely matches the absorption spectrum of at least one photo-initiator comprised in the curable adhesive composition. As a result, the laser light is capable to induce the decomposition of the at least one photo-initiator, thereby engaging the radical polymerization of the bonding agent (i.e. the monomer mixture). In a particular embodiment of the invention, said laser light has a wavelength of from 200 nm to 450 nm, preferably of from 350 nm to 420 nm, preferably of from 390 nm to 410 nm. In a preferred embodiment, said laser light has a wavelength of about 405 nm. In a particular embodiment, the duration of the curing step ranges from 0.1 to 50 seconds, preferably from 0.5 to 20 seconds, preferably from 1 to 5 seconds. In a particular embodiment, the laser used in the method of the invention has a power ranging from 20 to 500 milliwatts, preferably from 100 to 450 milliwatts, preferably from 200 to 300 milliwatts and is preferably of about 300 milliwatts.

The use of a laser light in the method of the invention advantageously allows a significant improve of the depth of cure of the curable adhesive composition of the invention, when compared to the lightning apparatus used in the art. Further, the use of a laser light advantageously and significantly improves the precision of the photoinduction signal triggering the cure of the adhesive composition. These beneficial advantages allow the light source (i.e. the laser) to be placed as far as liked from the first and second bodies to be bonded together. On the contrary, methods known in the art require the light source to be placed at a very close proximity of the adhesive composition to be cured. The laser may thus be positioned anywhere and easily oriented towards the curable adhesive composition due to the highly controllable directivity of the laser beam. The method of the present invention thus not only provides with a strong industrial interest, in facilitating the handling of the elements to be assembled, but also results in the depth curing of the adhesive composition, thereby strengthening the bond between the first body and the second body. Advantageously, the adhesive solution cured through the use of a laser light resulting from the process of the invention displays harness values at 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9- and 10-mm depth that are greater than 80%, preferably greater than 90%, even preferably greater than 95% of the surface hardness values. Surface hardness values may be measured according to methods known in the art, for instance by methods for measuring Vickers hardness. Further, the precision conferred by the laser light significantly reduces the phtototreatment of the first and second bodies when compared to the known curing methods of the art. As a result, reduced alteration of the structure and of the color of the first and/or second bodies is observed.

As used in the present invention, by "first body" and "second body", it is meant a first three-dimensional object and a second three-dimensional object, which are to be bonded together. In a particular embodiment, a contact surface of the first body is bonded to a contact surface of the second body through the use of the curable adhesive composition described above. In a particular embodiment the contact surfaces of the first and second bodies are substantially non-planar surfaces. In another embodiment, the surfaces offer an uneasy access or are not approachable for a light source to be brought close to the surfaces.

In a particular embodiment, the contact surfaces of the first body and the second body may be pretreated where necessary before the curable adhesive composition is applied. Pretreatments for use in the present invention encompass, in particular, physical and/or chemical cleaning methods, such as abrading, sandblasting, brushing or the like, or treatment with cleaners or solvents, or the application of an adhesion promoter, an adhesion-promoter solution or a primer

The first body and the second body for use in the method of the invention may be diverse in nature. They may be formed from plastics, metal, glass, ceramic, other materials or combinations of these materials. In a particular embodiment, the first body and/or the second body is made of plastic, more particularly a plastic selected from the group consisting of PVC, ABS, polycarbonate, poly(methyl(meth)acrylate) (PMMA), polyester, polyamide, modified polyethylene or propylene, such as air or low-pressure plasma-pretreated polyethylene or polypropylene, polystyrene and copolymers of styrene, such as ASA and SAN. In a particular embodiment, the first body and/or the second body is made of a metallic material, more particularly aluminium, iron, copper or alloys thereof, such as steel. In another embodiment, the first body and/or the second body is made of mineral, more particularly glass or glass ceramic.

Further, at least one of the first body or of the second body for use in the present invention is formed from a material that has been configured for being "transparent" to the electromagnetic radiation used for curing the curable adhesive composition.

As used in the present invention, by "transparent" or by "does not substantially absorbs the electromagnetic radiation", it is meant that at least one of the first body or of the second body is formed from a material that has been configured to transmit the electromagnetic radiation to which it is subjected in the course of the method of the invention. In a particular embodiment of the invention, at least one of the first body or of the second body is configured such that it is capable to transmit a light having a wavelength within the UV and/or visible portion of the electromagnetic spectrum such as to ensure that this light can reach the curable adhesive composition. In a particular embodiment, at least one of the first body or of the second body is configured for transmitting light, the wavelength of which is ranging from 200 nm to 450 nm, preferably form 350 nm to 420 nm, preferably from 390 nm to 410 nm, and is preferably of 405 nm.

By "transparent" or by "does not substantially absorbs the electromagnetic radiation", it is further meant that the material of at least one of the first body or of the second body is capable to transmit greater than 70% (and therefore absorbs less than 30%) of the electromagnetic radiation of interest, i.e of the light wavelength which is required for ensuring the curing of the curable adhesive composition. In a particular embodiment of the invention, it may be desirable to improve the aesthetics of the structure formed by the bonding of the first body and the second body, notably in selecting materials that absorb light at visible wavelength, and more particularly that absorb more than 70% (and therefore transmit less than 30%) of some or substantially all visible wavelengths.

In a particular embodiment, the first body and/or the second body for use in the invention is thus capable to absorb more than 70% for all visible wavelengths above 450 nm, preferably above 420nm, preferably above 410 nm, while simultaneously exhibiting a transmission of greater than 70% of light with a wavelength ranging from 200 nm to 450 nm, preferably from 350 nm to 420 nm, preferably from 390 to 410 nm, and preferably having a wavelength of 450 nm. Such an embodiment would indeed allow a light to pass through the material of the first and/or second bodies for curing the curable adhesive composition, while maintaining sufficient opacity at visible wavelengths for allowing the material to appear opaque to a user or other viewer of the bonded first and second bodies.

The method according to the invention advantageously results in an adhesively bonded article, formed by the bonded first and second bodies.

In a particular embodiment of the present invention, the first body is a cannula and the second body is a hub. As used in the present invention, by "non-planar surfaces" it is meant that the contact surfaces of the first and second bodies are not substantially planar, i.e. they do not lie essentially in a two-dimensional, substantially flat plane. Examples of non-planar surfaces include surfaces having an arcuate feature, or surfaces having more than one flat surface conjoined in differing two-dimensional planes. Such non-planar surfaces can include "open surfaces" (i.e. "sheets"), or "closed surfaces" (i.e. rods, tubes, among others). Such closed surfaces are able to be solid in nature (i.e. rods), hollow (i.e. tubes), and can include those surfaces having indentations (i.e. cylinders). The closed surfaces can be of any cross-sectional geometry, and such cross-section can include curved features, arcuate features, linear features, or any combination thereof. The cross- sectional geometry can include curved geometries (i.e. circles and ovals), or any linear geometry (squares, rectangles, triangles, or any n-faced geometry, regular and irregular).

The first and second bodies that are to be joined may be mounted to each other using a curable adhesive composition under a liquid form (i.e. when the said adhesive is in its uncured state). Assembly equipment, portions of the structures that are being joints, and/or assembly personnel may hold the first and second bodies in place prior to adhesive curing.

In a particular embodiment of the present invention, the said first body is a cannula and the said second body is a hub.

As used in the present invention, the term "cannula" refers to a piece of stainless steel or plastic tubing used to transfer liquids or gases without exposing said liquids or gases to air. Cannula may be inserted into the body, preferably the body of a mammal, such as human or animal body, and may be used for delivering or removing a fluid or a gas. Cannula may also be inserted in a container, such as a bag or a box, for introducing or removing a fluid or a gas therefrom. Typically, a cannula has a first end, an opposite end and a sidewall therebetween. It also includes a lumen therethrough, defining a cannula longitudinal axis.

As used in the present invention, the term "hub" means a device allowing a cannula to be hold firmly on a fluid transfer apparatus intended for collecting and/or injecting a fluid, such as for example a syringe, a tube or a catheter. In particular embodiments, hubs are removably attached to fluid transfer apparatus. A hub typically includes a proximal end for engaging a fluid transfer apparatus, a distal end and a passageway therethrough defining a hub longitudinal axis. The hub is assembled to the cannula such that the later cannot be easily removed. The cannula is positioned in the hub such that its first end projects outwardly from the distal end of the hub, its opposite end projects inwardly in the passageway of the hub, and fluid communication is maintained between the proximal and the distal ends of the hub through the lumen of the cannula. The cannula is hold in the hub in such a way that a sufficient force prevents the cannula from falling out of the hub. Preferably, the cannula is hold fixedly and immovably in the hub by an adhesive composition. The cannula-hub assembly may be used in a diverse number of environments and in conjunction with catheters, hypodermic needles, and various other needle arrangements used to direct and channel blood, parenteral fluids and medicines to and from the body. According to an embodiment, the hub is a luer- lock hub. According to an embodiment, the hub is made of any material that one skilled in the art would find suitable such as for example acrylonitrile butadiene styrene, acrylic, polycarbonate, polyethylene, polypropylene, polysulfone, polyurethane or a mixture thereof. In a particular embodiment, the curable adhesive composition is deposited according to a "pre-assembly" procedure. In another embodiment, the curable adhesive composition is deposited according to a "post-assembly" procedure.

The curable adhesive composition of the invention is provided such that the cannula sidewall and the innerwall of the hub passageway are tightly and immovably linked over a substantial part of their contact surfaces, in a manner such that no fluid may circulate between said cannula sidewall and said hub passageway innerwall.

Pre-assembly

According to one embodiment, the bonding method of the invention comprises the steps of inserting the cannula in the hub, applying the curable adhesive composition comprising the at least one photo-initiator at the distal end of the hub, and subjecting the assembly, and more specifically the region of the assembly where the adhesive solution is located, to a laser light such as for inducing the curing of said adhesive composition. In a particular embodiment, the curable adhesive composition is dispensed in the space between said hub and said cannula for ensuring that the cannula and the hub will be tighly bonded one to each other.

Post-assembly

According to another embodiment, the bonding method of the invention comprises the steps of applying the adhesive composition comprising the at least one photo-initiator at the distal end of the hub and/or on the cannula, inserting the cannula in the hub, and subjecting the assembly, and more specifically the region of the assembly where the adhesive solution is located, to a laser light such as to induce the cure of said adhesive composition. In such an embodiment, care should be taken not to let the adhesive composition to flow into the cannula lumen, for avoiding any risk of clogging the cannula.

According to one embodiment, the curable adhesive composition used for bonding the cannula and the hub by the pre-assembly process has a lower viscosity than the curable adhesive composition used for bonding the cannula and the hub by the post-assembly process.

According to one embodiment, the cannula has a bevel point or a blunt end.

Article comprising a cannula and a hub

In a particular embodiment, the present invention further concerns an article comprising a cannula and a hub bound together according to the method of the present invention. In a particular embodiment, the said article is obtainable by the process of the present invention. In another embodiment, the said article is obtained by the process of the invention.

In a particular embodiment of the invention, the said article is a syringe, a needle or a catheter. Advantageously, the article of the invention comprises a cannula and a hub fixedly and immovably bond together through a cured adhesive composition displaying a depth hardness which is significantly greater than that of the known equivalent dispositives of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a photograph showing a particular embodiment of an article comprising a hub and a cannula bond together by a curable adhesive composition according to the invention (bonding agent) and subjected to a laser light. Figure 2 is a photograph showing the result of the curing of a bonding agent as achieved by a process of the prior art implementing a LED light. As shown by the arrow, the cured bonding agent (C) presents a small thickness and a large area.

Figure 3 is a photograph showing the result of the curing of a bonding agent as achieved by a process according to an embodiment of the present invention. As shown by the arrow, the cured bonding agent (C) presents a precise small area and a large thickness.

EXAMPLE

An acryl-based adhesive solution comprising diphenyl (2, 4, 6- trimethylbenzoyl)phosphine oxide as photo-initiator was subjected to a light curing step under a LED lamp (5000 mW/cm ² for 2 seconds) or under a 405 nm laser beam (300 mW/cm ² for 2 seconds).

Results are provided in figures 2 and 3.

As can be seen in figure 2, the cured adhesive composition (C) presents a small thickness and a large area. On the contrary, figure 3 demonstrates that the adhesive composition subjected to the laser beam presents a precise small area and a large thickness.