CH712872B1 - Substrate comprising a surface coated with an epilame agent and method of epilamating such a substrate. - Google Patents

Abstract

The invention relates to a copolymer and to a substrate comprising a surface of which at least a part is covered with an epilame agent comprising at least one compound in the form of a copolymer comprising V units, N units, optionally in the form of a copolymer. at least one unit M and optionally at least one unit P, associated by covalent bonds by their main chains, where where W, X, Y, Z are spacer arms, T is a tracer group arranged to determine the concentration of epilame agent in a epilamage bath, L is a halogenated, preferably fluorinated, C 1 -C 20 carbon group, A constitutes an anchoring group to the substrate, Q is H, CH 3, or a hydrocarbon chain other than T. The invention also relates to a method of epilamating such a substrate, said method comprising a step of controlling the concentration of epilame agent in the epilame bath by means of the tracer group and, if necessary, a step of readjusting the concentration of agentepilame in the epilamage bath.

Description

Field of the invention

The present invention relates to the field of mechanics and in particular to the field of watchmaking or jewelry. It relates more particularly to a copolymer, as well as to a substrate, in particular a substrate of an element of a timepiece or jewelry piece comprising a surface covered at least partially with an epilame agent comprising such a copolymer. It also relates to a method of epilamating such a substrate, as well as a timepiece or jewelry piece comprising an element comprising such a substrate.

Background of the invention

There are various methods for modifying the surface state of a substrate by treatment with an appropriate agent so as to specifically improve certain surface properties. For example, in the field of mechanics, and in particular in the field of watchmaking, but also in the field of jewelry, epilamage of a surface of a part or of an element is often carried out at means of an epilame agent in order to control and reduce the surface energy of said surface during its use. More particularly, the purpose of an epilame agent is to prevent the spreading of oils or lubricants on the elements of a timepiece or jewelry piece by forming a hydrophobic and lipophobic surface allowing the lubricant to remain in a predetermined place of the watch. treated surface.

The standard epilamage process is a dip coating process. It consists of immersing the timepieces in an epilamating bath, that is to say a solution of the epilame agent in a solvent at a given concentration. The epilame effect depends on the concentration of epilame agent. Industrially, the same epilamating bath is used to epilamate timepieces for several months. As it is used, the amount of epilame agent in the bath decreases (part of the epilame agent remains adsorbed / attached to the timepieces) and the amount of solvent in the epilame agent solution also decreases by evaporation. Thus, during use, the concentration of epilame agent in the epilamage bath changes. To limit these fluctuations, industrially, a concentrated solution of epilame agent and / or of the solvent is regularly added to the epilame bath. On the other hand, these additions are made in a very empirical manner given that the current epilamation process does not allow precise information to be obtained on the concentration of epilame agent. This leads to epilame effects which vary significantly from batch to batch.

Summary of the invention

[0004] The object of the invention is in particular to overcome the various drawbacks of epilame agents and known epilamage processes.

[0005] More precisely, an objective of the invention is to provide an epilame agent as well as a depilamation process which make it possible to precisely know the concentration of epilame agent over time, in order to provide robustness. to the overall epilamage process.

To this end, the present invention relates to a copolymer comprising V units, N units, optionally at least one M unit and optionally at least one P unit, associated by covalent bonds by their main chains, where where R1, R2 , R3, R4, identical or different, are H, a C1-C10 alkyl group, C1-C10 alkenyl, and preferably H, CH3 W, X, Y, Z, identical or different, are spacer arms made up of a heteroatom or of a hydrocarbon chain which may contain at least one heteroatom, linear or branched, comprising at least one carbon atom T, identical or different, is a tracer group arranged to determine the concentration of copolymer in a medium L, identical or different, is a halogenated C1-C20 carbon group, preferably fluorinated A, identical or different, constitutes an anchoring group to the substrate, and is chosen from the group comprising thiols, thioethers, thioesters, sulphides, thioamides, silanols, alkoxysilanes, silane halides, hydroxyls, phosphates, phosphonic acids, protected or not , phosphonates, protected or not, amines, ammoniums, nitrogenous heterocycles, carboxylic acids, anhydrides, catechol Q, identical or different, is H, CH3, a hydrocarbon chain different from T, which may contain at least one heteroatom, linear or branched, saturated or unsaturated, comprising at least 2 carbon atoms.

The present invention also relates to a substrate comprising a surface of which at least a part is covered with an epilame agent, said epilame agent comprises at least one compound in the form of a copolymer comprising V units, N units, optionally at least one unit M and optionally at least one unit P, associated by covalent bonds by their main chains, where where R1, R2, R3, R4, identical or different, are H, an alkyl group in C1-C10, alkenyl in C1-C10, and preferably H, CH3 W, X, Y, Z, identical or different, are spacer arms made up of a heteroatom or of a hydrocarbon chain which may contain at least one heteroatom, linear or branched, comprising at least one carbon atom T, identical or different, is a tracer group arranged to determine the concentration of epilame agent in an epilame bath L, identical or different, is a halogenated C1-C20 carbon group, preferably fluorinated A, identical or different, constitutes an anchoring group to the substrate, and is chosen from the group comprising thiols, thioethers, thioesters, sulphides, thioamides, silanols, alkoxysilanes, silane halides, hydroxyls, phosphates, phosphonic acids, protected or not , phosphonates, protected or not, amines, ammoniums, nitrogenous heterocycles, carboxylic acids, anhydrides, catechol Q, identical or different, is H, CH3, a hydrocarbon chain different from T, which may contain at least one heteroatom, linear or branched, saturated or unsaturated, comprising at least 2 carbon atoms.

Such an epilame agent makes it possible to control and monitor the evolution of its concentration over time in the epilame bath.

[0009] The present invention also relates to a method of epilamating at least part of a surface of a substrate comprising the steps of: a) preparing an epilamating bath containing an epilame agent comprising at least one copolymer as defined above b) optionally, preparation of the surface of the substrate c) control of the concentration of epilame agent in the epilamating bath by means of the tracer group d) optionally readjusting the concentration of epilame agent in the bath epilamage e) bringing the surface of the substrate into contact with the epilame agent in the epilamage bath f) drying.

The present invention also relates to the use, as epilame agent of at least part of a surface of a substrate, in particular intended for watches or jewelry, of a copolymer comprising V units, N units, optionally at least one M unit and optionally at least one P unit, associated by covalent bonds by their main chains, where where R1, R2, R3, R4, identical or different, are H, a C1- alkyl group C10, C1-C10 alkenyl, and preferably H, CH3 W, X, Y, Z, identical or different, are spacer arms made up of a heteroatom or of a hydrocarbon chain which may contain at least one heteroatom, linear or branched, comprising at least one carbon atom T, identical or different, is a tracer group arranged to determine the concentration of epilame agent in an epilame bath L, identical or different, is a halogenated C1-C20 carbon group, preferably fluorinated A, identical or different, constitutes an anchoring group to the substrate, and is chosen from the group comprising thiols, thioethers, thioesters, sulphides, thioamides, silanols, alkoxysilanes, silane halides, hydroxyls, phosphates, phosphonic acids, protected or not , phosphonates, protected or not, amines, ammoniums, nitrogenous heterocycles, carboxylic acids, anhydrides, catechol Q, identical or different, is H, CH3, a hydrocarbon chain different from T, which may contain at least one heteroatom, linear or branched, saturated or unsaturated, comprising at least 2 carbon atoms, to control the concentration of epilame agent in an epilamage bath.

The present invention also relates to a timepiece or jewelry piece comprising an element comprising a substrate as defined above.

Brief description of the drawings

Other features and advantages will emerge clearly from the description which is given below, by way of indication and in no way limiting, with reference to the accompanying drawings, in which: FIG. 1 represents absorbance curves as a function of wavelength for different concentrations of copolymer I in a solvent; FIG. 2 is the calibration curve for copolymer I representing the absorbance as a function of the concentration at the wavelength λ = 336 nm FIG. 3 represents absorbance curves as a function of the wavelength for different concentrations of copolymer II in a solvent; and FIG. 4 is the calibration curve for copolymer II representing the absorbance as a function of the concentration at the wavelength λ = 336 nm.

Detailed description of the invention

According to the present invention, a substrate, in particular a substrate of an element of a timepiece or jewelry, comprises a surface at least part of which is covered with an epilame agent, said epilame agent comprising at least one compound in the form of a copolymer comprising V units, N units, optionally at least one M unit and optionally at least one P unit, associated by covalent bonds by their main chains, where where R1, R2, R3 , R4, identical or different, are H, C1-C10 alkyl, C1-C10 alkenyl, and preferably H, CH3 W, X, Y, Z, identical or different, are spacer arms made up of a heteroatom or of a hydrocarbon chain which may contain at least one heteroatom, linear or branched, comprising at least one carbon atom T, identical or different, is a tracer group arranged to determine the concentration of epilame agent in an epilame bath L, identical or different, is a halogenated C1-C20 carbon group, preferably fluorinated A, identical or different, constitutes an anchoring group to the substrate, and is chosen from the group comprising thiols, thioethers, thioesters, sulphides, thioamides, silanols, alkoxysilanes, silane halides, hydroxyls, phosphates, phosphonic acids, protected or not , phosphonates protected or not, amines, ammoniums, nitrogenous heterocycles, such as imidazole or pyridine, carboxylic acids, anhydrides, catechol Q, identical or different, is H, CH3, a hydrocarbon chain different from T, which may contain at least one heteroatom, linear or branched, saturated or unsaturated, comprising at least 2 carbon atoms.

The invention also relates to a copolymer intended to form the epilame agent, and comprising V units, N units, optionally at least one M unit and optionally at least one P unit, associated by covalent bonds by their main chains. , where where R1, R2, R3, R4, identical or different, are H, C1-C10 alkyl, C1-C10 alkenyl, and preferably H, CH3, W, X, Y, Z, identical or different, are spacer arms made up of a heteroatom or of a hydrocarbon chain which may contain at least one heteroatom, linear or branched, comprising at least one carbon atom T, identical or different, is a tracer group arranged to determine the concentration of copolymer in a medium L, identical or different, is a halogenated C1-C20 carbon group, preferably fluorinated A, identical or different, constitutes an anchoring group to the substrate, and is chosen from the group comprising thiols, thioethers, thioesters, sulphides, thioamides, silanols, alkoxysilanes, silane halides, hydroxyls, phosphates, phosphonic acids, protected or not , phosphonates, protected or not, amines, ammoniums, nitrogenous heterocycles, such as imidazole or pyridine, carboxylic acids, anhydrides, catechol Q, identical or different, is H, CH3, a hydrocarbon chain different from T, which may contain at least one heteroatom, linear or branched, saturated or unsaturated, comprising at least 2 carbon atoms.

Preferably, the copolymer comprises only V, N and optionally M and / or P units.

The copolymer of the invention can be a random copolymer in which the units V, N, M and P are statistically linked together by their main chain, that is to say distributed randomly, so that the random copolymer can be written in the form:

The copolymer of the invention can be a block copolymer comprising at least one block of V units associated by covalent bonds by their main chains, at least one block of N units associated by covalent bonds by their main chains, to the least one of the block of units V and of the block of units N optionally comprising at least one unit M and optionally at least one unit P, associated by covalent bonds by their main chains, said blocks being connected to each other by covalent bonds by their main chains in linear sequences.

The block copolymer can be written in the form:

Preferably, the block copolymer comprises a single block of V units and a single block of N units, at least one of the V unit block and of the N unit block optionally comprising at least one unit. M and / or a P unit. When present, the number y1 of M units and the number w1 of P units in unit block V may vary from the number y2 of M units and the number w2 of P units respectively in the N units block.

Preferably, the P units are integrated and distributed within the block composed of N units, for example by statistical copolymerization of P units with N units to form a single block consisting mainly of N units and assimilated to a unit block N.

Preferably, the M units are integrated and distributed within the block composed of N units, for example by statistical copolymerization of M units with N units to form a single block consisting mainly of N units and assimilated to a unit block N.

Advantageously, the groups W, X, Y, Z, identical or different, are chosen from the group comprising ester groups in C1-C20, preferably in C2-C10, more preferably in C2-C6 , and even more preferably at C2-C5, preferably alkyl ester groups, preferably linear, amide groups, and groups derived from styrene.

Preferably, T, identical or different, is a UV absorber group or a fluorophore. Such groups make it possible, for example, to determine the concentration of copolymer by spectroscopy. It is obvious that any other type of tracer followed by suitable detection and analysis means can be used.

Advantageously, T, identical or different, is a UV absorber group derived from a compound chosen from the group comprising benzotriazoles, triazines, phenones (in particular benzophenone, acetophenone, hydroxyalkylphenone, hydroxyarylphenone, amino alkylphenone , anthraquinone), acyl phosphine oxides.

Advantageously, T, identical or different, is a fluorophore group derived from a compound chosen from the group comprising fluorescein, a naphthyl, anthracene, coumarin, rhodamine, a fluorobenzoate.

The functional groups of interest A are capable of reacting with the surface of the substrate to be epilamated, so as to constitute anchoring groups of the epilame agent on the surface of the substrate. Advantageously, groups A can also be provided at the end of the copolymer.

Advantageously, the copolymer comprises at least two different A groups.

The functional groups of interest L are responsible for the epilame effect. They comprise at least one halogen atom, preferably a fluorine atom. Preferably, L is a carbon group, ie an alkyl chain, which may be cyclic, preferably without heteroatom, at C2-C20, preferably at C4-C10, and more preferably at C6-C9. L is partially or totally halogenated. Advantageously, L is an at least partially fluorinated group, and preferably totally fluorinated. L can also include a hydrogen atom on the terminal group. L is preferably a perfluorinated alkyl chain.

The functional groups of interest Q of the P units are used to modify the properties of the epilame agent and / or provide other functions. For example, Q can be an alkyl chain, preferably C8-C20, used to modify the contact angle obtained or a chain capable of constituting crosslinking points during a complementary crosslinking step (step g). For example, the P units can be derived from stearyl methacrylate.

Preferably, the copolymer comprises, in molar percentage, between 1% and 20%, preferably between 3% and 10% of V units, between 50% and 99%, preferably between 70% and 95% d 'N units, between 0% and 50%, preferably between 1% and 20%, and more preferably between 5% and 20% of M units, and between 0% and 50%, preferably between 0% and 20% , and more preferably between 0% and 10% of P units, the percentages being expressed relative to the total number of units (w + x + y + z).

Advantageously, the copolymer comprises between 10 and 350 units (w + x + y + z).

In a particularly advantageous manner, the M, N, P units are chosen to carry several A groups of different nature, several L groups, preferably of the same nature, and optionally one or more Q groups which may be identical or of different nature, so as to refine and improve the properties of the epilame agent, in order to obtain more specifically a universal epilame agent and having an improved affinity with the substrate.

Preferably, the surface of the substrate, at least part of which is covered with the epilame agent, is made of a material chosen from the group comprising metals, metal oxides, doped or not, polymers, sapphire, ruby, silicon, silicon oxides, silicon nitrides, silicon carbides, DLC (Diamond Like Carbon), and their alloys.

More specifically, the surface of the substrate can be made of steel, or of noble metals such as gold, rhodium, palladium, platinum, or of metal oxides, doped or not with aluminum, zirconium, titanium, chromium, manganese, magnesium, iron, nickel, copper, zinc, molybdenum, silver, tungsten, or polyoxymethylene or acrylamide, as well as their alloys.

The present invention also relates to a method of epilamating at least part of a surface of a substrate comprising the steps of: a) preparing an epilamating bath containing an epilame agent comprising at least one copolymer as defined above b) optionally, preparation of the surface of the substrate, in particular by cleaning according to standard watchmaking processes, c) control of the concentration of epilame agent in the epilame bath by means of the tracer group d) optionally readjustment of the epilame agent concentration in the epilame bath e) bringing the surface of the substrate into contact with the epilame agent in the epilame bath f) drying.

It is obvious that step a) can be implemented at a distance over time from the other steps b), c), d) and f). Preferably, for example when the epilamation process is carried out continuously or when the same epilamation bath is used several times, steps c) and d) can be repeated in order to control the concentration of epilame agent. over time so as to keep this concentration constant for the implementation of step e).

Advantageously, when the T group is a UV absorber group or a fluorophore, the determination of the concentration of epilame agent is carried out by spectroscopy (absorbance measurement for example). An intermediate step, prior to step c) provides for the preparation of a calibration curve for the copolymer. For this, the copolymer is dissolved at different concentrations in a solvent (same solvent as that used for the preparation of the epilame agent solution) and for each solution the absorbance is measured by spectroscopy as a function of the wavelength.

The wavelength for which the absorbance is maximum is identified and then the calibration curve A = F (concentration) is plotted at the wavelength for which the absorbance is maximum. The molar extinction coefficient of the polymer is deduced therefrom (Beer Lambert law A = εcl).

To control the concentration of epilame agent in the epilamating bath according to step c), it is then sufficient to measure the absorbance of the solution of the bath by spectroscopy, then by using the previously established calibration curve of deduce the concentration of epilame agent in the epilamage bath. The operator can thus add solvent or concentrated solution of epilame agent to precisely readjust the concentration, in accordance with step d). In the context of a continuous epilamating process for example or when the same epilamating bath is used several times, several checks of the epilame agent concentration make it possible to monitor the evolution of the epilame agent concentration during time so as to keep it constant.

Preferably, the preparation of the epilame agent is carried out by random or block copolymerization of monomers capable of forming the V units with monomers capable of forming the N units, optionally with monomers capable of forming at least one unit. M and optionally with monomers capable of forming at least one P unit.

Statistical or block copolymerization techniques are well known to those skilled in the art and do not require a detailed description. A particularly suitable mode of polymerization for random copolymerization is free radical copolymerization, in solution or in emulsion.

According to a first variant, the random copolymer can be obtained in a single step by copolymerization, preferably radical, of monomers bearing the side chains ZT with monomers bearing the side chains XL and optionally monomers bearing the side chains Y- A and / or optionally monomers carrying the WQ side chains.

According to another variant, the random copolymer can be obtained by copolymerization, preferably radical, of monomers bearing the appropriate Z side chains with monomers bearing the appropriate X side chains and optionally monomers bearing side chains intended to carry A and / or optionally monomers carrying side chains intended to carry Q, then the side chains are modified after the polymerization (post-functionalization), for example by "click chemistry", to introduce therein the functional groups of interest T, L , and groups A and / or Q.

A particularly suitable mode of polymerization for block copolymerization is the successive controlled copolymerization: of monomers capable of forming at least one block of V units and optionally with monomers capable of forming at least one M unit and / or of monomers capable of forming at least one P unit monomers capable of forming at least one block of N units, and optionally with monomers capable of forming at least one M unit and / or monomers capable of forming at least one identical or different P, M or P unit.

Two particularly suitable modes of polymerization for block copolymerization are radical copolymerization by atom transfer (ATRP) and radical polymerization controlled by reversible chain transfer by addition-fragmentation (RAFT), in solution or in emulsion.

According to a first variant, the block copolymer can be obtained by polymerization, preferably controlled radical, of monomers bearing the side chains ZT with optionally monomers bearing the side chains Y-A and / or optionally monomers bearing the side chains WQ, followed by the copolymerization, preferably controlled radical, of monomers bearing the XL side chains with optionally monomers bearing the Y-A side chains and / or optionally monomers bearing the identical or different WQ, Y-A and WQ side chains .

According to another variant, the block copolymer can be obtained by polymerization, preferably controlled radical, of monomers bearing the appropriate Z side chains with optionally monomers bearing side chains intended to bear A and / or optionally monomers bearing side chains intended to carry Q, followed by the copolymerization, preferably controlled radical, of monomers carrying the appropriate X side chains with optionally monomers carrying side chains intended to carry A and / or optionally monomers carrying side chains intended to carry Q, then the side chains are modified, for example by "click chemistry", to introduce the functional groups of interest T, L and the groups A and / or Q.

Preferably, the monomers are chosen from the group comprising acrylate, methacrylate, acrylamide, methacrylamide, vinyl, diene, styrene and olefinic monomers. The acrylate, methacrylate, acrylamide, methacrylamide, vinyl and styrenic monomers are particularly preferred. These products are known and for the most part available on the market or accessible in a synthetic step.

The particularly preferred monomers for forming the V units comprising a tracer group T are chosen from the group comprising 2-H-benzotriazol-2-yl-hydroxyphenyl ethyl methacrylate, 2- (2H-Benzotriazol-2-yl) -4-methyl-6- (2-propenyl) phenol, 2- (4-Benzoyl-3-hydroxyphenoxy) ethyl acrylate, 4-Allyloxy-2-hydroxybenzophenone, 2-Naphthyl (meth) acrylate, Fluorescein O - (meth) acrylate, 9-Anthracenylmethyl (meth) acrylate, Ethidium bromide-N, N'-bisacrylamide, N- (1-Naphthyl) -N-phenylmethacrylamide, 7- [4- (Trifluoromethyl) coumarin ] methacrylamide. Such monomers are commercially available and are polymerizable.

Even more preferably, the monomers to form the V units comprising a tracer group T are chosen from the group comprising 2-H-benzotriazol-2-yl-hydroxyphenyl ethyl methacrylate, 2- (2H-Benzotriazol-2- yl) -4-methyl-6- (2-propenyl) phenol, 2- (4-Benzoyl-3-hydroxyphenoxy) ethyl acrylate, 4-Allyloxy-2-hydroxybenzophenone. These monomers contain tracer groups that can be followed by UV-visible spectroscopy, which is much easier to set up in an industrial environment than fluorescence spectroscopy.

Particularly preferred monomers for forming the N, M and P units are:

Thus, the copolymer used as epilame agent can be easily obtained in a single step or a limited number of steps from marketed products.

One of the copolymers preferably used in the present invention is a random copolymer which has the following structure (I)

Another copolymer preferably used in the present invention is a random copolymer which has the following structure (II):

The copolymers used in the invention can be obtained in the form of powder or viscous liquid. They can then be dissolved in a fluorinated solvent, such as perfluorinated or fluorinated hydrocarbons, perfluoropolyethers, hydrofluoroolefins, hydrofluoroethers, at concentrations preferably between 50 mg / L and 250 mg / L, in order to obtain an epilame agent solution, which will be used for the treatment of surfaces to be epilamated.

According to the variants, the epilamage process according to the invention may further comprise, after step e), a step g) of additional crosslinking, made possible in particular by the presence of the appropriate functional groups of interest provided. on the Q side chains of P units.

The substrate according to the invention has a surface covered with an epilame agent which is simple and economical to synthesize, exhibiting an affinity with any type of substrate and an improved resistance to washing compared to known epilame agents. An element or a part having a substrate in accordance with the invention can be used in all types of applications in the mechanical field, and more particularly in precision mechanics, and in particular in watchmaking and jewelry.

The method according to the invention makes it possible to control and monitor the concentration of epilame agent in the epilame bath over time in order to be able to adequately readjust the composition of the epilame agent bath in epilame. Thus, the concentration of epilame agent in the epilame bath is substantially constant so that the epilame effects are constant for all of the batches treated. A robust epilamage process is thus obtained.

The following examples illustrate the present invention without, however, limiting its scope.

Synthesis of 3-methacryloxopropyl methyl thioether: (according to a procedure similar to that described in US patent 6'552'103)

In a three-necked flask under magnetic stirring placed under nitrogen are added thiomethylpropanol (4.05mL), dichloromethane (100mL) and triethylamine (8.2mL). The solution is cooled in an ice bath and then methacrylate chloride (3.8 mL) is added dropwise over 10 min. The reaction mixture is stirred for 2 h at 0 ° C. then at room temperature overnight. 70 mL of water are added and then the reaction mixture is transferred to a separating funnel. The organic phase and the aqueous phase are separated. The organic phase is washed with an HCl solution (pH = 4) until pH = 7 is reached and then dried over Na2SO4. The solvent is then removed on a rotary evaporator to yield the expected product with a yield of 97%.

<1> H NMR (CDCl3, 500MHz): chemical shift (ppm): 6.10 (s, 1H), 5.56 (s, 1H), 4.24 (t, 2H), 2.58 (t, 2H), 2.11 ( s, 3H), 1.99 (m, 2H), 1.94 (s, 3H)

Example 1

An epilame agent is synthesized in the form of a random copolymer by free radical polymerization of: - (3-methacryloxopropyl) dimethyl-methoxysilane - 1H, 1H, 2H, 2H-Perfluorooctylacrylate - 3-methacryloxopropyl methyl thioether prepared as is 'indicated above - 2- [3- (2H-Benzotriazol-2-yl) -4-hydroxyphenyl] ethyl methacrylate according to the following procedure: in a Schlenk tube containing cyclohexanone (2mL) previously degassed with nitrogen , are added 2- [3- (2H-Benzotriazol-2-yl) -4-hydroxyphenyl] ethyl methacrylate (148 mg), (3-methacryloxopropyl) dimethyl-methoxysilane (166µL), 3-

Methacryloxopropyl methylthioether (111μL) then 1H, 1H, 2H, 2H-Perfluorooctylacrylate (2.0 mL). The reaction medium is bubbled 5 min with nitrogen and then 0.8 ml of hydrofluoroether (Novec ™ HFE-7200 3M ™) previously bubbled with nitrogen are added. 0.5mL of a 0.228mol / L azobisisobutyronitrile (AIBN) solution is added. The reaction medium is stirred and heated at 80 ° C. for 3 h. The polymer is coagulated in methanol and then rinsed with 3 * 30mL of methanol. The polymer is obtained in the form of a slightly whitish gel (yield = 95%).

The following random copolymer (I) is obtained:

UV absorbance measurement:

The copolymer (I) is dissolved at various concentrations in a fluorinated solvent, type Ecosolv (Moebius) identical to the solvent used in the epilamage bath. For each concentration, the absorbance is measured by UV-visible spectroscopy. The curves represented in FIG. 1 are obtained. The wavelength for which the absorbance is maximum is located at 336 nm, which makes it possible to determine the molar absorption coefficient of the polymer at the maximum absorption at 336 nm. It is then possible to establish a calibration curve, as shown in FIG. 2, by representing the absorbance as a function of the copolymer concentration. This calibration curve then makes it possible to determine the copolymer concentration in the epilamage bath at all times by a simple absorbance measurement by UV-visible spectroscopy carried out from samples of the epilamage bath taken. Depending on the result obtained, the operator knows whether to add solvent or concentrated epilame agent solution in order to precisely readjust the epilame agent concentration in order to maintain a substantially constant concentration during the epilamation process.

Example 2

An epilame agent is synthesized in the form of a random copolymer by free radical polymerization of: - 2- (2,2-Diphenyl-benzo [1,3] dioxo-5-yl) -ethyl-acrylate (obtained by reaction between - (2,2-Diphenyl-benzo [1,3] dioxo-5-yl) -ethylamine (commercially available) and acryloyl chloride) - 1H, 1H, 2H, 2H-Perfluorooctylacrylate - 3-acryloxopropyl methyl thioether (obtained according to the procedure described in the literature: Preparation of biomimetic polymer hydrogel materials for contact lenses Bertozzi, Carolyn et al. US 6552103) - 2- [3- (2H-Benzotriazol-2-yl) -4-hydroxyphenyl ] ethyl methacrylate according to the following procedure: in a Schlenk tube containing cyclohexanone (2mL) degassed beforehand with nitrogen, are added 2- [3- (2H-Benzotriazol-2-yl) -4-hydroxyphenyl] ethyl methacrylate (162 mg), 2- (2,2-Diphenylbenzo [1,3] dioxo-5-yl) -ethyl-acrylate (373 mg), 3-acryloxopropyl methylthioether (111µL) then 1H, 1H, 2H , 2H-Perfluorooctylacrylate (2.1 mL ). The reaction medium is bubbled 5 min with nitrogen and then 0.8 ml of hydrofluoroether (Novec ™ HFE-7200 3M ™) previously bubbled with nitrogen are added. 0.55mL of a 0.228mol / L azobisisobutyronitrile (AIBN) solution is added. The reaction medium is stirred and heated at 80 ° C. for 3 h. The polymer is coagulated in methanol and then rinsed with 3 * 30mL. The polymer is obtained in the form of a slightly whitish gel (yield = 92%).

The following random copolymer is obtained:

The protective group of the catechol function of the polymer is then removed (deprotection of the catechol function) according to the following operating method: The polymer obtained previously is dissolved in 50 mL of fluorinated solvent (Novec ™ HFE-7200 3M ™), then 5 ml of Trifluoroacetic acid are added with stirring. The reaction is left under stirring for 1 hour. The mixture is then washed with 4 x 40 mL of water, the organic phases are collected then the fluorinated solvent reduced to a minimum. The polymer is coagulated in methanol and then rinsed with 3 * 30mL. The polymer is obtained in the form of a slightly whitish gel (yield = 75%). The following random copolymer (II) is obtained:

UV absorbance measurement:

The copolymer (II) is dissolved at various concentrations in a fluorinated solvent, Ecosolv type (Moebius), identical to the solvent used in the epilamage bath. For each concentration, the absorbance is measured by UV-visible spectroscopy. The curves shown in FIG. 3. The wavelength for which the absorbance is maximum is obtained is obtained at 336 nm, which makes it possible to determine the molar absorption coefficient of the polymer at the maximum absorption at 336 nm. It is then possible to establish a calibration curve, as shown in FIG. 4, by representing the absorbance as a function of the copolymer concentration. This calibration curve then makes it possible to determine the copolymer concentration in the epilamage bath at all times by a simple absorbance measurement by UV-visible spectroscopy carried out from samples of the epilamage bath taken. Depending on the result obtained, the operator knows whether to add solvent or concentrated epilame agent solution in order to precisely readjust the epilame agent concentration in order to maintain a substantially constant concentration during the epilamation process.

Claims (24)

1. Copolymer comprising V units, N units, optionally at least one M unit and optionally at least one P unit, associated by covalent bonds by their main chains, where where R1, R2, R3, R4, identical or different, are H, C1-C10 alkyl, C1-C10 alkenyl, and preferably H, CH3 W, X, Y, Z, identical or different, are spacer arms made up of a heteroatom or of a hydrocarbon chain which may contain at least one heteroatom, linear or branched, comprising at least one carbon atom T, identical or different, is a tracer group arranged to determine the concentration of copolymer in a medium L, identical or different, is a C 1 -C 20 halogenated carbon group, preferably fluorinated A, identical or different, constitutes an anchoring group to the substrate, and is chosen from the group consisting of thiols, thioethers, thioesters, sulphides, thioamides, silanols, alkoxysilanes, silane halides, hydroxyls, phosphates, phosphonic acids, protected or not , phosphonates, protected or not, amines, ammoniums, nitrogenous heterocycles, carboxylic acids, anhydrides and catechol Q, identical or different, is H, CH3, a hydrocarbon chain different from T, which may contain at least one heteroatom, linear or branched, saturated or unsaturated, comprising at least 2 carbon atoms. 2. Copolymer according to claim 1, characterized in that W, X, Y, Z, identical or different, are chosen from the group consisting of ester groups C1-C20, preferably C2-C10, amide groups, and groups derived from styrene. 3. Copolymer according to one of the preceding claims, characterized in that T, identical or different, is a UV absorber group or a fluorophore. 4. Copolymer according to one of the preceding claims, characterized in that T, identical or different, is a UV absorber group derived from a compound chosen from the group consisting of benzotriazoles, triazines, phenones and acyl oxides. -phosphine. 5. Copolymer according to one of claims 1 to 3, characterized in that T, identical or different, is a fluorophore group derived from a compound selected from the group consisting of fluorescein, naphthyl, anthracene, coumarin , rhodamine and a fluorobenzoate. 6. Copolymer according to one of the preceding claims, characterized in that L is a carbon group C2-C20 halogenated, preferably C4-C10. 7. Copolymer according to one of the preceding claims, characterized in that L is an at least partially fluorinated group, preferably totally fluorinated. 8. Copolymer according to one of the preceding claims, characterized in that it comprises, in molar percentage, between 1% and 20%, preferably between 3% and 10% of V units, between 50% and 99%, preferably between 70% and 95% of N units, between 0% and 50%, preferably between 1% and 20% of M units, and between 0% and 50%, preferably between 0% and 20% d 'P. 9. Copolymer according to one of the preceding claims, characterized in that it comprises between 10 and 350 units. 10. Substrate comprising a surface of which at least a part is covered with an epilame agent, characterized in that said epilame agent comprises at least one compound in the form of a copolymer comprising V units, N units, optionally at least a unit M and optionally at least one unit P, associated by covalent bonds by their main chains, where where R1, R2, R3, R4, identical or different, are H, an alkyl group in C1-C10, alkenyl in C1-C10 , and preferably H, CH3 W, X, Y, Z, identical or different, are spacer arms made up of a heteroatom or of a hydrocarbon chain which may contain at least one heteroatom, linear or branched, comprising at least one carbon atom T, identical or different, is a tracer group arranged to determine the concentration of epilame agent in an epilame bath L, identical or different, is a halogenated C1-C20 carbon group, preferably fluorinated A, identical or different, constitutes an anchoring group to the substrate, and is chosen from the group consisting of thiols, thioethers, thioesters, sulphides, thioamides, silanols, alkoxysilanes, silane halides, hydroxyls, phosphates, phosphonic acids, protected or not , phosphonates, protected or not, amines, ammoniums, nitrogenous heterocycles, carboxylic acids, anhydrides and catechol Q, identical or different, is H, CH3, a hydrocarbon chain other than T, which may contain at least one heteroatom, linear or branched, saturated or unsaturated, comprising at least 2 carbon atoms. 11. Substrate according to claim 10, characterized in that W, X, Y, Z, identical or different, are chosen from the group consisting of ester groups C1-C20, preferably C2-C10, amide groups, and groups derived from styrene. 12. Substrate according to one of claims 10 and 11, characterized in that T, identical or different, is a UV absorber group derived from a compound chosen from the group consisting of benzotriazoles, triazines, phenones and oxides of acyl-phosphine. 13. Substrate according to one of claims 10 and 11, characterized in that T, identical or different, is a fluorophore group derived from a compound chosen from the group consisting of fluorescein, naphthyl, anthracene, coumarin , rhodamine and a fluorobenzoate. 14. Substrate according to one of claims 10 to 13, characterized in that L is a C2-C20 halogenated carbon group, preferably C4-C10. 15. Substrate according to one of claims 10 to 14, characterized in that L is an at least partially fluorinated group, preferably totally fluorinated. 16. Substrate according to one of claims 10 to 15, characterized in that the copolymer comprises, in molar percentage, between 1% and 20%, preferably between 3% and 10% of V units, between 50% and 99 %, preferably between 70% and 95% of N units, between 0% and 50%, preferably between 1% and 20% of M units, and between 0% and 50%, preferably between 0% and 20 % of P. 17. Substrate according to one of claims 10 to 16, characterized in that the copolymer comprises between 10 and 350 units. 18. Substrate according to one of claims 10 to 17, characterized in that its surface, at least part of which is covered with the epilame agent is made of a material chosen from the group consisting of metals, metal oxides, polymers. , sapphire, ruby, silicon, silicon oxides, silicon nitrides, silicon carbides and DLC (Diamond Like Carbon). 19. A method of epilamating at least part of a surface of a substrate comprising the steps of: a) preparation of an epilame bath containing an epilame agent comprising at least one copolymer as defined in claims 1 to 9 b) optionally, preparation of the substrate surface c) control of the concentration of epilame agent in the epilamage bath by means of the tracer group d) optionally readjusting the concentration of epilame agent in the epilame bath e) bringing the surface of the substrate into contact with the epilame agent in the epilame bath f) drying. 20. Epilamage process according to claim 19, characterized in that said epilamage process is continuous and in that steps c) and d) are repeated over time. 21. Epilamage process according to one of claims 19 and 20, characterized in that the preparation of the epilame agent is carried out by copolymerization of monomers capable of forming the V units with monomers capable of forming the N units, optionally. with monomers capable of forming at least one M unit and optionally with monomers capable of forming at least one P unit, the monomers being chosen from the group consisting of acrylate, methacrylate, acrylamide, methacrylamide, vinyl and styrene monomers. 22. Epilamage method according to one of claims 19 to 21, characterized in that it further comprises, after step e), a step g) of additional crosslinking. 23. Use, as epilame agent of at least part of a surface of a substrate, of a copolymer comprising V units, N units, optionally at least one M unit and optionally at least one P unit, associated. by covalent bonds through their main chains, where where R1, R2, R3, R4, identical or different, are H, a C1-C10 alkyl, C1-C10 alkenyl, and preferably H, CH3 W, X, Y, Z, identical or different, are spacer arms made up of a heteroatom or of a hydrocarbon chain which may contain at least one heteroatom, linear or branched, comprising at least one carbon atom T, identical or different, is a tracer group arranged to determine the concentration of epilame agent in an epilame bath L, identical or different, is a halogenated C1-C20 carbon group, preferably fluorinated A, identical or different, constitutes an anchoring group to the substrate, and is chosen from the group consisting of thiols, thioethers, thioesters, sulphides, thioamides, silanols, alkoxysilanes, silane halides, hydroxyls, phosphates, phosphonic acids, protected or not , phosphonates, protected or not, amines, ammoniums, nitrogenous heterocycles, carboxylic acids, anhydrides and catechol Q, identical or different, is H, CH3, a hydrocarbon chain different from T, which may contain at least one heteroatom, linear or branched, saturated or unsaturated, comprising at least 2 carbon atoms, to control the concentration of epilame agent in an epilamage bath. 24. Timepiece or jewelry comprising an element comprising a substrate according to any one of claims 10 to 18.