Use of a linear siloxane polymer as epilame agent

Abstract

The present invention relates to the use of a linear polymer based on siloxanes as an epilame agent in the field of watchmaking or jewelry.

Description

FIELD OF INVENTION

[0001] The present invention relates to the use of a linear siloxane-based polymer as an epilame agent and a method of epilameing at least part of a surface of a component of a watch or jewelry piece. PRIOR STATE OF TECHNOLOGY

[0002] In the field of watchmaking, the durability of components and the absence of friction during the operation of watch movements are improved by the presence of lubricants (oils, greases) applied to the surface of the parts of the watch components.

[0003] A common problem in this field is the potential migration (spreading) of the lubricant across the entire surface of the part. This spreading depends on the surface tension of the lubricant on the part's surface. If this surface tension is greater than that of the surface on which the lubricant is applied, then the lubricant does not migrate and therefore remains in place. Conversely, if the surface tension of the lubricant is too low, the lubricant spreads, which limits, or even eliminates, its effectiveness.

[0004] A well-known and commonly used technique to avoid this problem is surface coating of the part to be lubricated. This involves applying a thin, invisible hydrophobic and lipophobic layer to the surface of the component. This lipophobic layer, for example in the form of a monolayer, repels the lubricant, allowing it to remain in a predetermined area of ​​the treated surface. Keeping the lubricant within its operating zone also increases its lifespan.

[0005] An epilame is therefore a molecule that allows modification of the wettability properties of a surface.

[0006] Epilame molecules, developed in recent years, are composed of 2 parts: an "anchor" part (anchoring group), generally hydrophilic, which will serve as a chemical graft with the surface of the part to be treated, and a hydrophobic functional body providing the epilame properties to the molecule, via fluorinated groups for example.

[0007] Thus, during epilaming, the hydrophobic parts of the epilame agent align and self-assemble to form a self-assembled molecular monolayer.

[0008] Currently, the vast majority of epilaminate agents contain fluorinated groups, such as perfluorinated groups, which provide the required hydrophobicity and lipophobicity to the surfaces they coat. In particular, bisphosphonic compounds bearing a perfluorinated or perfluoropolyether group have demonstrated the ability to reduce surface tension, thereby controlling the wettability of the surfaces they coat and achieving good epilaminate properties.

[0009] The depilating process is traditionally carried out by dipping (dip coating) the parts to be treated in a depilating bath consisting of a perfluorinated or fluorinated solvent solution loaded with depilating agent.

[0010] However, regulations, particularly regarding pollution and the degradability of developed materials, are becoming increasingly strict in order to contribute to environmental preservation and reduce environmental impact.

[0011] Indeed, numerous studies have recently demonstrated the negative impact of fluorinated compounds, particularly perfluorinated compounds, on the environment and human health. More specifically, these compounds are volatile, difficult to degrade, and thus easily end up in the air, soil, water, flora, and throughout the food chain, ultimately reaching humans.

[0012] It is therefore necessary to find an alternative to these compounds which can prove to be dangerous and toxic.

[0013] Silanes are well-known in the watchmaking industry, but their development was limited by several problems. Silane-type coatings, such as silicone polymers, adhered to the surface of the parts to be coated using Van der Waals forces. However, these interactions were too weak to maintain the coating's adhesion. Consequently, the silicone polymers would detach, for example, during treatments such as washing. In particular, the observed migration of the silicone polymer over time resulted in stains on untreated surfaces. These stains were difficult to clean, visible, and detracted from the aesthetics of the watch component.

[0014] Surprisingly, the Applicant has developed a new siloxane-based polymer compound, specifically polydimethylsiloxanes (PDMS), which exhibits properties suitable for use as an epilame. In particular, this polymer has a contact angle with an oil droplet comparable to that of a molecular layer obtained from a fluorinated polymer.

[0015] Unlike previous art, this siloxane polymer does not lead to any aesthetic defects on the surfaces to which it is applied. Furthermore, it does not require the use of fluorinated compounds, either the epilame or the solvent used during epilaming.

[0016] Its use in the depilation of watch or jewelry parts surfaces leads to the formation of a homogeneous molecular layer on said surface and, as already indicated, does not require the use of a fluorinated or perfluorinated solvent.

[0017] The invention thus makes an important contribution to the ecological preparation of willowherbs. DESCRIPTION OF THE INVENTION

[0018] One aim of the invention is to provide a new, more environmentally friendly epilame agent that exhibits the oleophobic properties necessary for a watchmaking or jewelry application.

[0019] The use and application of this epilame agent has the following characteristics in particular: Thin molecular layer Homogeneous layer easily deposited in production on all types of watch or jewelry component(s) Layer not leading to aesthetic defects (e.g. stains, white haze) Low surface energy to avoid capillarity problems of lubricants Non-fluorinated solvent (optional) with rapid drying.

[0020] The polymer used according to the invention makes it possible to obtain an epilame effect on the surfaces of watch or jewelry parts and to limit the spreading of lubricants on these surfaces.

[0021] More specifically, the present invention relates to the use of a linear siloxane-based polymer as an epilame agent in the watchmaking or jewelry industry, the polymer comprising a main chain comprising n siloxane units [Si(O)(CH3)2]n and at least one Alk-A anchoring group to a surface of a component of a watch or jewelry piece, where n is an integer between 10 and 500, Alk is a spacer represented by a linear or branched, saturated or unsaturated hydrocarbon chain comprising between 1 and 10 carbon atoms and optionally comprising one or more heteroatoms, preferably a linear C2-C5 hydrocarbon chain, A is a terminal group represented by R1<-C(H2PO3)2 or -N(R2<)(R3<), R1< is a hydrogen atom H or an OH group, R2< and R3< are, independently of each other, a hydrogen atom or a linear or branched hydrocarbon chain comprising from 1 to 10 carbon atoms, possibly including one or more unsaturations.

[0022] The polymer according to the invention is fluorine-free.

[0023] The invention also relates to a method for removing the polish from at least part of a surface of a watch or jewelry piece, comprising the following steps: a) preparation of a depilating bath containing the polymer according to the invention, b) optionally, preparation of the surface of a watch or jewelry piece, c) bringing the surface to be depilated into contact with the polymer in the depilating bath, d) rinsing and drying of the surface.

[0024] The invention also relates to a watch or jewelry item comprising a component having a part covered, on the surface and at least partially, with the polymer according to the invention. DESCRIPTION OF THE INVENTION

[0025] For the purposes of this invention, "epilame" refers to a hydrophobic behavior intended to prevent the spreading of oils or lubricants on the components of a watch or jewelry piece by forming a hydrophobic and lipophobic (or oleophobic) surface allowing the lubricant to remain in a predetermined location, outside the treated surface.

[0026] Similarly, the term "epilamage process" refers to a process of coating at least part of a surface of a component of a watch or jewelry piece in order to prevent the spreading of liquid lubricants.

[0027] In the context of the invention, the terms "epilamage process" and "recovery process" are interchangeable.

[0028] For the purposes of this invention, "lubricant" means oils or greases, in particular oils (or base oils in the case of greases) having a kinematic viscosity measured at 20 °C of between 10 and 2000 mm² / s, and a surface tension measured at 20 °C of between 25 and 40 mN / m.

[0029] As already mentioned, the present invention relates to the use of a linear siloxane-based polymer as an epilame agent in the watchmaking or jewelry industry, the polymer comprising a main chain comprising n siloxane units [Si(O)(CH3)2]n and at least one Alk-A anchoring group to a surface of a component of a watch or jewelry piece, where n is an integer between 10 and 500, Alk is a spacer represented by a linear or branched, saturated or unsaturated hydrocarbon chain comprising between 1 and 10 carbon atoms and optionally comprising one or more heteroatoms, preferably a linear C2-C5 hydrocarbon chain, A is a terminal group represented by R1<-C(H2PO3)2 or -N(R2<)(R3<), R1< is a hydrogen atom H or an OH group, R2< and R3< are, independently of each other, a hydrogen atom or a linear or branched hydrocarbon chain comprising from 1 to 10 carbon atoms, possibly including one or more unsaturations.

[0030] The siloxane-based polymer (hereinafter referred to as siloxane polymer) is used as an epilame agent on at least part of a surface of a component of a watch or jewelry piece.

[0031] Thus, the use of the polymer makes it possible to limit the spreading of substances such as lubricants on at least part of a surface of a component of a watch or jewelry piece.

[0032] The polymer exhibits identical or even improved epilamal properties compared to prior art compositions.

[0033] The polymer advantageously comprises the Alk-A anchoring group at one end of the main chain, thus forming a terminal A-Alk-Si(O)(CH3)2- group.

[0034] Preferably, the polymer comprises two Alk-A anchoring groups at each end of the main chain, thus forming two terminal A-Alk-Si(O)(CH3)2- groups.

[0035] In preferred embodiments, the polymer has the following formula (I): A-Alk-Si(O)(CH3)2-[Si(O)(CH3)2]n-Si(CH3)2-Alk-A.

[0036] Advantageously, the polymer can further comprise p units [Si(O)(CH3)(Alk-A)], p being advantageously between 0.01(n+p) and 0.5(n+p).

[0037] Thus, in this case, the Alk-A anchoring group is located on the side chains of siloxane units.

[0038] The [Si(O)(CH3)(Alk-A)] units are typically distributed randomly or in block(s) on the main chain.

[0039] In preferred embodiments, the polymer has the following formula (II): H3C-Si(O)(CH3)2-[Si(O)(CH3)2]n[Si(O)(CH3)(Alk-A)]p-Si(CH3)2-CH3.

[0040] Advantageously, the Alk-A anchoring group has the formula -(CH 2 ) m -N(R 2< )(R 3< ), m being an integer between 1 and 10, advantageously between 2 and 5.

[0041] Preferably, R2 < = R3 < = H.

[0042] In particular, the siloxane polymer according to the invention is preferably selected from the group consisting of polymers having one of the following CAS numbers: 106214-84-0 and 99363-37-8. These polymers are represented in the Figures 3 And 4 .

[0043] In the context of the invention, the siloxane polymer is free of fluorine atoms. In order to obtain the required epilame properties, the siloxane polymer has a surface tension lower than that of the lubricants present in the components of a watch or jewelry piece, which makes it possible to limit, or even avoid, the migration of lubricants.

[0044] Advantageously, the surface of the component of a watch or jewelry piece coated with the siloxane polymer has a surface energy between 5 and 30 mJ / m², preferably between 10 and 25 mJ / m², even more preferably between 15 and 25 mJ / m².

[0045] To be effective as an epilame, that is to say to satisfactorily prevent the spreading of the lubricant, the polymer has an advance contact angle with the oil advantageously of at least 40°, preferably of at least 50° and even more preferably of at least 60°.

[0046] Surface energy and contact angle are measured conventionally at 25°C using a goniometer (e.g., DSA25 or DSA30). The contact angle is determined according to the adapted protocol of ASTM D5946-09. Measurements are performed using a conventional watch lubricant (oil) for tribological contact.

[0047] Advantageously, the lead contact angle (θ on the figure 2 ) with the oil is less than 100°, preferably is less than 90° and even more preferably is less than 80°.

[0048] Advantageously, the siloxane polymer is used pure or in a composition comprising a non-fluorinated solvent. The composition is advantageously free of fluorinated compounds.

[0049] This composition is typically in liquid form.

[0050] The use of the polymer, whether pure or in a compound, will depend on its viscosity. For example, for a viscosity above 1000 cST (centistokes; 1 cST = 10⁻⁶ m² / s), the polymer will be diluted with a non-fluorinated solvent to form a liquid compound. Below 1000 cST, the polymer is preferably used pure.

[0051] The polymer typically has a viscosity between 10 cST and 5,000 cST.

[0052] Advantageously, the composition is a liquid composition comprising a non-fluorinated solvent for solubilizing the siloxane polymer. This non-fluorinated solvent is advantageously selected from the group consisting of: water; alcoholic solvents, in particular C1-C6 alcohols such as isopropanol, ethanol, or methanol; glycol ethers, advantageously 1-methoxy-2-propanol, glycols (advantageously ethylene glycol and propylene glycol); silicones, advantageously polydimethylsiloxane (CAS number: 9016-00-6); CX-C(=O)-OC Y esters, where x is from 1 to 6 and y is from 1 to 6, advantageously butyl acetate; C3-C8 aldehydes; C3-C6 ketones such as acetone; C2-C6 ethers such as diethyl ether or tetrahydrofuran; alkanes, especially C5-C8 alkanes; C1-C6 alkyl halides, especially dichloromethane; and mixtures thereof.

[0053] Advantageously, the non-fluorinated solvent has a flash point above 40°C, more advantageously above 70°C and even more advantageously above 100°C.

[0054] This composition advantageously comprises from 0.0001 to 20% by weight of siloxane polymer, preferably 0.1 to 10% by weight, relative to the weight of the composition.

[0055] When using siloxane polymer, the part or the surface of the part advantageously comprises more than 50% (by weight): of a metal selected from iron (Fe), titanium (Ti), aluminum (Al), nickel (Ni), ruthenium (Ru), rhodium (Rh), tin (Sn), gold (Au), platinum (Pt), silver (Ag), copper (Cu), and mixtures thereof, or of an alloy selected from steel (an alloy of iron and carbon), stainless steel, brass (an alloy of copper and zinc), nickel silver (an alloy of copper, nickel, and zinc), bronze (an alloy of copper and tin), tin-nickel (Sn-Ni), nickel-phosphorus (Ni-P), copper-beryllium (Cu-Be), palladium-nickel (Pd-Ni), copper-cobalt (Cu-Co), or of an alloy comprising at least one metal selected from vanadium (V), chromium (Cr), manganese (Mn), zinc (Zn), tungsten (W), zirconium (Zr), and mixtures thereof, or an alloy with an amorphous crystalline structure, or a ceramic or a glass such as ruby ​​(an alloy of aluminium oxide and chromium), sapphire (aluminium oxide), zirconia, silica or alumina,or a semiconductor such as silicon (Si) or germanium (Ge), as well as their oxides, or diamond.

[0056] The part or the surface of the part may be made of one of the materials listed above or of at least two of these materials.

[0057] The surface of the part is preferably made of a material chosen from the group consisting of: iron (Fe), titanium (Ti), alloys, ruby, and silicon. It may, in particular, be an iron alloy, for example, an alloy chosen from the group consisting of: steel (an alloy based on iron and carbon), stainless steel (an alloy based on iron and chromium), and nickel-phosphorus (Ni-P). It may also be a surface made of a traditional watchmaking coating, for example, gold plating, rhodium plating, or nickel plating.

[0058] Advantageously, the surface of the part is the surface of an escape wheel or pallet of a watch movement.

[0059] The invention also relates to a method for removing the outer layer of at least part of a surface of a component of a watch or jewelry piece, comprising the following steps: a) preparation of a depilating bath containing the polymer as described above b) optionally, preparation of the surface of a watch or jewelry piece, c) bringing the surface to be depilated into contact with the polymer in the depilating bath, d) rinsing and drying of the surface.

[0060] This process makes it possible to cover at least part of a surface of a watch or jewelry piece with a molecular layer that is both hydrophobic and lipophobic (or oleophobic), allowing the lubricant to remain in a predetermined area of ​​the surface of the watch or jewelry piece.

[0061] Furthermore, this process eliminates the need for expensive and polluting fluorinated solvent-based hair removal baths, and also eliminates the need for any monitoring of the treatment bath. This process, therefore, is environmentally friendly and economical, easy to implement, and provides a high-performance, permanent hair removal effect.

[0062] The quality of hair removal obtained by the process according to the invention is at least identical to that obtained with a traditional hair removal process using fluorinated compounds.

[0063] Step a) of the process consists of preparing the depilatory bath.

[0064] This depilating bath may contain the pure polymer or in the form of a composition.

[0065] In the latter case, the siloxane polymer composition is prepared by dissolving the polymer in a non-fluorinated solvent.

[0066] As mentioned above, the use of pure polymer or polymer in a compound form will be determined by the polymer's viscosity. If necessary, a skilled professional will know how to adjust the amount of polymer to prepare a hair removal bath in compound form.

[0067] Step b) advantageously includes the preparation of the surface to be coated with siloxane polymer.

[0068] Preparation refers to cleaning and / or degreasing the surface of the part. Cleaning aims in particular to remove all traces of dust and particles. Degreasing is advantageously carried out by washing the surface to be epilaminated with a non-fluorinated organic solvent, followed by drying. All appropriate surface preparation treatments known to those skilled in the art may be used.

[0069] The process may optionally include a step b') of surface activation, for example dehydration and / or oxidation of the surface to be coated (surface of a watch or jewelry piece), in order to functionalize the surface of the piece with hydroxyl functions, which allows for a greater coating of the surface of the watch or jewelry piece.

[0070] The process includes, after step b) or optionally step b'), bringing the surface of the part to be coated into contact with the polymer in the de-epilating bath (step c)) to form a monolayer covering said surface. The layer thus formed covers the treated surface homogeneously.

[0071] The surface is brought into contact with the polymer for a period typically ranging from 1 second to 12 hours, preferably between 1 second and 1 hour, preferably from 1 second to 5 minutes, and even more preferably between 1 second and 1 minute. A person skilled in the art will be able to adjust the contact time according to the conditions.

[0072] The polymer is advantageously brought into contact with the surface of the part by dipping, spin-coating, wiping, sponging, vaporizing, aerosolizing, deposition using an oil pick or similar tool, or spraying.

[0073] In particular embodiments, the contact of the polymer of the invention with the surface of the part can be achieved by physical means, for example by a physical deposition of the plasma type, in particular cold plasma.

[0074] When the siloxane polymer composition is gaseous, contact with the substrate surface can be achieved using a reactor with controllable pressure and temperature.

[0075] When the siloxane polymer composition is liquid, step c) is advantageously carried out at a temperature between 10 and 45°C, more advantageously between 15 and 25°C.

[0076] Once the siloxane polymer layer has formed on the surface of the watch or jewelry piece, the piece is separated from the wax bath and the excess polymer is advantageously removed (step c')) so as to remove from the surface the solvent, if present, and the siloxane polymer that did not adhere to the surface upon contact.

[0077] The siloxane polymer can be removed by rinsing, or mechanically by draining, centrifugation, or evaporation. The surface can also be rinsed, in particular by immersion in a suitable non-fluorinated solvent, to ensure complete removal of the unbound polymer. This non-fluorinated solvent is preferably selected from the list defined above. The rinsing solvent may be the same as the solvent used to prepare the polymer in its composition form; it may also be different.

[0078] To improve the adhesion of the siloxane polymer to the surface of the part, the part may optionally undergo a chemical curing step (step c), advantageously by heating and preferably under reduced pressure. A person skilled in the art will be able to select these parameters, which are part of their general knowledge, and adapt them appropriately according to the part being treated. This optional step is advantageously carried out at a temperature between 50 and 300 °C, more advantageously between 50 and 150 °C. It is advantageously carried out at a pressure between 0.01 and 1 bar (10³ to 10⁵ Pa). It is advantageously carried out in an oven.

[0079] Step d) of rinsing and drying the coated surface is conventional and also well known to the person in the trade.

[0080] The invention also relates to a watch or jewelry item comprising a component having a part covered, on the surface and at least partially, with the siloxane polymer.

[0081] A watch part is specifically referred to as the mechanical parts of a watch movement.

[0082] Jewelry items are referred to as jewelry articles and ornaments such as fashion accessories. FIGURES

[0083] There Figure 1 illustrates a network of unorganized molecules on the surface of a watch or jewelry piece. Figure 2 represents the contact angle between a liquid and a surface of a watch or jewelry component. Figure 3 represents the siloxane polymer with CAS number 106214-84-0. Figure 4 represents the siloxane polymer with CAS number 99363-37-8. Figures 5A, 5B and 5CThese are photographic images of, respectively, the surface of Finemac steel, ruby, and silica (SiO2) components before epilamulation. Figure 6 is a photographic image grouping the components of Figures 5A, 5B and 5C after epilation with EP2. The Figure 7 is a photographic image grouping the components of Figures 5A, 5B and 5C after epilation with EP3. The Figures 8A, 8B and 8C represents, respectively, the surface appearance of Finemac steel, ruby, and silica (SiO2) components before epilamulation performed with a HIROX microscope. Figures 9A, 9B and 9C represents, respectively, the surface appearance of Finemac steel, ruby, and silica (SiO2) components after epilamulation with EP2 performed using a HIROX microscope. Figures 10A, 10B and 10C represents, respectively, the surface appearance of Finemac steel, ruby ​​and SiO2 silica components after epilaming with EP3 carried out with a HIROX microscope. EXAMPLES Material

[0084] Epilame 1 (EP1): Poly(dimethylsiloxane), terminated bis(3-aminopropyl) (CAS 106214-84-0, number-average molecular weight 2500 g / mol).

[0085] Epilame 2 (EP2): Poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane] (CAS 99363-37-8).

[0086] Epilame 3 (EP3): Poly(dimethylsiloxane), terminated bis(3-aminopropyl) (CAS 106214-84-0, number-average molecular weight 27,000 g / mol). Parts treated by epilamage:

[0087] Nickel-Phosphorus alloy Armaflex Rhodium-plated alloy watch part (bridge) Finemac steel Ruby Silica SiO2 Example 1: Epilaming process and evaluation of the contact angle with different alloys

[0088] Various watch or jewelry pieces made of different alloys were coated with one of the EP1, EP2 or EP3 epilames, either pure or in liquid form.

[0089] Before coating, the surfaces of the parts to be epilamed were washed with heptane and ethanol successively and then dried.

[0090] The surfaces were then placed in an oven at 100 °C for 1 hour, then cooled in a desiccator.

[0091] Epilamage baths contain epilame pure or diluted in a non-fluorinated solvent.

[0092] EP3 is diluted with dichloromethane (5% by weight).

[0093] The pieces are immersed in the depilation bath overnight, before being rinsed with heptane and then dried at room temperature.

[0094] In the case of EP3, the part is dried, before the heptane rinsing step, in an oven at a temperature between 50 °C and 120 °C.

[0095] The contact angle of the parts' surfaces was determined using a DSA30 goniometer. The contact angle was determined according to the adapted protocol of ASTM D5946-09. The results are presented in the table below. Part (alloy) Epilame Contact angle (standard deviation) in degrees NiP Armaflex - 16.0 (1.2) Rhodium-plated bridge - 9.8 (1.2) Finemac - 17.0 (1.3) Ruby - 16.8 (0.6) SiO2 - 22.7 (1.3) NiP Armaflex EP2 52.3 (0.9) Rhodium-plated bridge EP2 53.2 (0.5) Finemac EP2 50.9 (1.0) Ruby EP2 51.2 (0.5) SiO2 EP2 51.4 (1.1) NiP Armaflex EP3 69.3 (1.3) Rhodium-plated bridge EP3 66.3 (1.7) Finemac EP3 68.8 (2.7) Ruby EP3 66.5 (2.2) SiO2 EP3 67.9 (0.66)

[0096] The results demonstrate a significant increase in the contact angle achieved with the epilames according to the invention on various surfaces. These results show that the polymers according to the invention constitute a viable alternative to conventional fluorinated polymers. Example 2: Visual appearance of the surface of parts treated with polysiloxanes the invention

[0097] The visual appearance of the surfaces of the parts before epilamling (after pre-treatment) ( Figures 5 And 8 ) and after epilation with EP2 ( Figures 6 And 9 ) and EP3 ( Figures 7 and 10 ) is illustrated on the Figures 5 to 10 .

[0098] THE figures 8 to 10 show the more detailed surface of the pieces before and after covering with epilame, carried out using an optical microscope.

[0099] The parts are made of Finemac steel ( Figures 5A , 8A, 9A and 10A ), Ruby ( Figures 5B , 8B, 9B and 10B ) and SiO2 ( Figures 5C , 8C, 9C and 10C ).

[0100] The visual appearance of the surfaces is unchanged after coating with EP2 and EP3 epilames. The epilamed surfaces show no aesthetic defects, stains, or any other deterioration after epilaming.

Claims

1. Use of a linear siloxane-based polymer as an epilame agent in the watchmaking or jewelry industry, the polymer comprising a main chain of n siloxane units [Si(O)(CH3)2] and at least one Alk-A anchoring group to a surface of a component of a watch or jewelry piece, where n is an integer between 10 and 500, Alk is a spacer represented by a linear or branched, saturated or unsaturated alkyl chain of between 1 and 10 carbon atoms and optionally comprising one or more heteroatoms, Alk preferably being a linear C2-C5 hydrocarbon chain, and A is a terminal group represented by R 1 -C(H2PO3)2 or -N(R 2 (R 3 ), R 1 is a hydrogen atom H or a group OH, R 2 and R 3are, independently of each other, a hydrogen atom or a hydrocarbon chain, linear or branched, comprising from 1 to 10 carbon atoms, possibly including one or more unsaturations.

2. Use according to claim 1, characterized in that the polymer includes an Alk-A anchoring group at one end of the main chain, forming a terminal A-Alk-Si(O)(CH3)2- group.

3. Use according to claim 1 or 2, characterized in that the polymer comprises two Alk-A anchoring groups at each end of the main chain, forming two terminal A-Alk-Si(O)(CH3)2- groups.

4. Use according to any one of the preceding claims, characterized in that the polymer comprises p units [Si(O)(Me)(Alk-A)] distributed randomly or in block(s) on the main chain, p being advantageously between 0.01(n+p) and 0.5(n+p).

5. Use according to any one of the preceding claims, characterized in thatthe Alk-A anchoring group has the formula -(CH2) m -N(R 2 (R 3 (m being an integer between 1 and 10, advantageously between 2 and 5.

6. Use according to any one of the preceding claims, characterized in that A is - N(R 2 (R 3 ) with R 2 =R 3 =H.

7. Use according to any one of the preceding claims, characterized in that the polymer is free of fluorine atoms.

8. Use according to any one of the preceding claims, characterized in that the polymer is selected from the group consisting of polymers having one of the following CAS numbers: 106214-84-0 and 99363-37-8.

9. Use according to any one of the preceding claims, characterized in that the polymer is used pure or in the form of a composition free of fluorinated solvent.

10. A method for de-epilating at least part of a surface of a component of a watch or jewelry piece comprising the following steps: a) preparation of a de-epilating bath containing the polymer as defined in any one of claims 1 to 9, b) optionally, preparation of the surface of the component of the watch or jewelry piece, c) bringing the surface to be de-epilated into contact with the polymer in the de-epilating bath, d) rinsing and drying of the surface.

11. Method according to claim 10, characterized in thatThe surface of the watch or jewelry component comprises more than 50% by weight of: - a metal chosen from iron, titanium, aluminum, nickel, ruthenium, rhodium, tin, gold, platinum, silver, copper, and mixtures thereof, or - an alloy chosen from steel, stainless steel, brass, nickel silver, bronze, tin-nickel, nickel-phosphorus, copper-beryllium, palladium-nickel, copper-cobalt, or - an alloy comprising at least one metal chosen from vanadium, chromium, manganese, zinc, tungsten, zirconium, and mixtures thereof, or - an alloy with an amorphous crystalline structure, or - a ceramic or glass such as ruby, sapphire, zirconia, silica, or alumina, or - a semiconductor such as silicon or germanium, as well as their oxides, or - diamond.

12. Method according to claim 10 or 11, characterized in thatThe depilatory bath comprises a non-fluorinated solvent chosen from the group consisting of: water; alcoholic solvents, in particular C1 to C6 alcohols; glycol ethers; silicones; C esters X -C(=O)-OC Y , x being between 1 and 6 and y being between 1 and 6; C3 to C8 aldehydes; C3 to C6 ketones; C2 to C6 ethers; alkanes, in particular C5 to C8 alkanes; C1 to C6 alkyl halides; and mixtures thereof 13. A method according to any one of claims 10 to 12, characterized in that the process includes a step b') of surface activation, such as a step of dehydration and / or oxidation of the surface of the component of the watch or jewelry part, so as to functionalize the surface of the part with hydroxyl functions.

14. A watch or jewelry item comprising a component having a part covered, on the surface and at least partially, with the polymer as defined in claims 1 to 9.

15. Timepiece according to claim 14, characterized in that The part is a mechanical component of a watch movement.

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