EP3638733A1

EP3638733A1 - Composition comprising a fluorinated polymer and a silane compound

Info

Publication number: EP3638733A1
Application number: EP18748966.1A
Authority: EP
Inventors: Marie-France Delamotte; St phane DORNIER; Nicolas CHABAN; Manuel Hidalgo
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2017-06-15
Filing date: 2018-06-13
Publication date: 2020-04-22
Also published as: FR3067716A1; FR3067716B1; CN110809604A; WO2018229436A1

Abstract

The invention relates to a composition comprising: a polymer PF comprising units derived from vinylidene fluoride; and – a silane agent of formula SiR₁R₂R₃R₄, wherein R₁, R₂, R₃ and R₄ are chemical groups connected by single bond to the Si atom; in solution in a solvent. The invention also relates to the use of this composition for producing electronic devices.

Description

COMPOSITION COMPRISING A FLUORINATED POLYMER

AND A SILANE COMPOUND

FIELD OF THE INVENTION

The invention relates to a fluoropolymer-based ink with improved adhesion to a substrate and to the use of this ink in the manufacture of electronic devices.

TECHNICAL BACKGROUND

Fluorinated polymers such as polyvinylidene fluoride (PVDF) and copolymers derived therefrom have a large number of uses, in particular wherein they are deposited as a film on a substrate.

Thus, it is known to manufacture electroactive copolymers based on vinylidene fluoride (VDF) and trifluoroethylene (TrFE), which may optionally contain a third monomer such as chlorotrifluoroethylene (CTFE) or 1,1-chlorofluoroethylene (CFE). Other copolymers, based on VDF and hexafluoropropene (HFP), have a utility for forming a protective layer of electronic devices, as described in patent application No. FR 16/58014 filed August 29, 2016.

The deposition of such fluoropolymers in film form can be performed from a formulation called "ink", consisting of a solution of the fluoropolymer, and optionally additives, in a good solvent.

In a large number of applications, it is required that the thin films obtained from these inks exhibit good adhesion properties with respect to different substrates or layers composing the structure of organic or inorganic devices. However, fluorinated polymers often have insufficient adhesive properties, and sometimes even nonstick properties, because of their low surface tension.

A Study on Interfacial Adhesion of Poly (Vinylidene

Fluoride) With Substrates in a Multilayer Structure, by Whang et al., In Polymer Engineering and Science, 35: 666-672 (1995) discloses the deposition of a layer of 3-aminopropyltriethoxysilane on a silicon substrate, followed by the deposition of a layer of PVDF.

Adhesive and Anticorrosive Properties of Poly (vinylidene fluoride) Powders Blended with Phosphonated Copolymers on Galvanized Steel Plates, by Bressy-Brondino et al., Inc. J. Appl. Polym. Sci. 83: 2277-2287 (2002) discloses a blend of PVDF and an organophosphorus copolymer having adhesive and anticorrosive properties.

The document Effects of surface treatment with coupling agents of PVDF-HFP fibers on the enhancement of adhesion characteristics on PDMSO, by Kwon et al., In Applied Surface Science 321: 378-386 (2014) discloses a fiber surface treatment of copolymer P (VDF-HFP) with in particular silane coupling agents, to improve their adhesion to polydimethylsiloxane.

There is a need to enhance the adhesive properties of the fluoropolymer films deposited in the form of inks, by using a simple deposition process and by altering as little as possible (or, ideally, improving) the properties of these films. SUMMARY OF THE INVENTION

The invention firstly relates to a composition comprising:

a polymer PF comprising units derived from vinylidene fluoride; and

a silane agent, of formula S1R1 R2R3R4, in which R1, R2, R3 and R4 are chemical groups connected by single bond to the Si atom;

in solution in a solvent.

In certain embodiments, the polymer PF also comprises units derived from at least one other monomer of formula wherein each group X1, X2, X3 and X ₄ is independently selected from H, Cl, F, Br, I and alkyl groups comprising 1 to 3 carbon atoms, which are optionally partially or fully halogenated; and preferably the polymer PF comprises units derived from at least one monomer chosen from trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, 1,1-chlorofluoroethylene, hexafluoropropene, 3,3,3-trifluoropropene, 1, 3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene and 2-chloro-3,3,3-trifluoropropene. In certain embodiments, the polymer PF comprises units derived from trifluoroethylene, the proportion of units originating from trifluoroethylene being preferably from 15 to 55 mol% relative to the sum of the units derived from vinylidene fluoride and trifluoroethylene.

In certain embodiments, the polymer PF further comprises units derived from an additional monomer, said additional monomer being preferably chlorotrifluoroethylene or 1,1-chlorofluoroethylene, and the proportion of units derived from the additional monomer being preferably from 1 to 20 mol%, more preferably from 2 to 15 mol%, based on all the units of the polymer PF.

In certain embodiments, the polymer PF comprises units derived from hexafluoropropene, preferably in a proportion of 2 to 50 mol%, more preferably 5 to 40 mol%, relative to all the units of the polymer PF.

In some embodiments, the silane agent has a molecular weight less than or equal to 2000 g / mol, preferably less than or equal to 1000 g / mol, more preferably less than or equal to 500 g / mol, and more particularly lower or equal to 200 g / mol.

In some embodiments:

R 1, R 2 and R 3 each represent a C ₁ -C ₄ alkoxy group, and R ₄ represents a C 1 -C 10 alkyl group, optionally halogenated in whole or in part, and optionally comprising a terminal function, which preferably is chosen from among the functions amine, vinyl, (meth) acrylic and glycidyl; or

the silane agent is a silazane.

In some embodiments, the silane agent is selected from 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, fluoroalkylsilanes, vinyltrimethoxysilane, and combinations thereof.

In some embodiments, the PF polymer is present in a proportion of 70 to 99.99% by weight, and preferably in a weight ratio of 80 to 99.8% by weight; and the silane agent is present in a proportion of 0.01 to 30% by weight, and preferably 0.2 to 20% by weight; the proportions being given with respect to the sum of the polymer PF and the silane agent.

In certain embodiments, the solvent is chosen from dimethylformamide, dimethylacetamide, dimethylsulfoxide and ketones, in particular acetone, methylethylketone, methylisobutylketone and cyclopentanone, furans, especially tetrahydrofuran; esters, in particular methyl acetate, ethyl acetate, propyl acetate, butyl acetate and propylene glycol methyl ether, carbonates, especially dimethyl carbonate, phosphates, especially triethylphosphate, and mixtures thereof.

The invention also relates to a method for preparing a composition as described above, comprising dissolving the PF polymer in the solvent, supplying the silane agent, and mixing them.

The invention also relates to a method of manufacturing a polymer film, comprising depositing the above composition on a substrate, and evaporation of the solvent from the composition.

The invention also relates to an electronic device, comprising a substrate coated with a polymer film manufactured according to the method above.

In some embodiments, the polymer film is an electroactive polymer film; or the polymer film is a protective film.

In some embodiments, the electronic device is an optoelectronic device and / or is selected from transistors, in particular field effect, chips, batteries, photovoltaic cells, light-emitting diodes, in particular organic light-emitting diodes, sensors , actuators, transformers, haptics, microelectromechanical systems and detectors.

The invention also relates to the use of a silane agent of formula S1R1 R2R3R4, wherein Ri, R2, R3 and R ₄ are chemical moieties linked by single bond to the Si atom, to improve adhesion of a PF polymer comprising units derived from vinylidene fluoride and units derived from trifluoroethylene on a substrate.

In some embodiments, the silane agent and the PF polymer are as described above.

The invention also relates to the use of a silane agent of formula S1R1 R2R3R4, wherein Ri, R2, R3 and R ₄ are chemical moieties linked by single bond to the Si atom, to improve the saturation polarization and / or the remanent polarization of a film comprising a polymer PF comprising units derived from vinylidene fluoride and units derived from trifluoroethylene.

The present invention makes it possible to meet the need of the state of the art. It provides more particularly an ink composition comprising a fluoropolymer dissolved in a solvent, for making a film (i.e., a layer) of fluoropolymer on a substrate having improved adhesion to the state of the art in a simple manner, and with little or no alteration of the properties of the film. In some embodiments, the electrical properties of the film (especially remanent polarization and / or saturation polarization) are improved.

This is achieved by combining the fluoropolymer with a silane agent in the ink composition from which the fluoropolymer is deposited on a substrate in a solvent route. The present inventors have indeed found that the presence of the silane agent, even at a low concentration, makes it possible to obtain films having an improved adhesion with respect to different substrates such as in particular glass and metals.

In addition, it has been found that the presence of the silane agent, preferably in small amounts, does not substantially affect the properties of the fluoropolymer films, whether electroactive properties or planarization properties or passivation for example, depending on the case.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is now described in more detail and without limitation in the description which follows.

The composition according to the invention comprises a polymer PF and a silane agent, in solution in a solvent.

Polymer PF

The PF polymer has structural units (or units, or repeating units, or units) that are derived from (i.e. obtained by polymerization of) vinylidene fluoride (VDF) monomers.

In some embodiments, the PF polymer is a PVDF homopolymer.

It is however preferred that the polymer PF is a copolymer (in the broad sense), that is to say that it comprises units derived from at least one other monomer X than VDF.

A single monomer X may be used, or several different X monomers, depending on the case.

In some embodiments, monomer X may be of formula CXiX2 = CX3X4 wherein each X group, X 2, X 3 and X ₄ is independently selected from H, Cl, F, Br, I, and alkyl groups C1 -C3 (preferably C1-C2), which are optionally partially or fully halogenated - this monomer X being different from VDF (that is to say that if Xi and X2 are H, at least one of X 3 and X ₄ is not F; and when X1 and X2 represent F, in least one of X 3 and X ₄ is not H).

In some embodiments, each group X1, X2, X3 and

X4 independently represents an H, F, Cl, I or Br atom, or a methyl group optionally comprising one or more substituents selected from F, Cl, I and Br.

In some embodiments, each X1, X2, X3 and X4 moiety independently represents an H, F, Cl, I or Br atom.

In some embodiments, only one of X 1, X _2, X ₃ and X ₄ represents a Cl or I or Br atom, and the other groups X 1, X _2, X ₃ and X ₄ independently represent: an H or F atom or a group C1-C3 alkyl optionally having one or more fluorine substituents; preferably, an H or F atom or a C 1 -C 2 alkyl group optionally comprising one or more fluorine substituents; and more preferably, an H or F atom or a methyl group optionally comprising one or more fluorine substituents.

Examples of monomers X are: vinyl fluoride (VF), trifluoroethylene (TrFE), tetrafluoroethylene (TFE), hexafluoropropene (HFP), trifluoropropenes and in particular 3,3,3-trifluoropropene, tetrafluoropropenes and in particular 2,3,3,3-tetrafluoropropene or 1,3,3,3-tetrafluoropropene (in cis or preferably trans form), hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropenes and especially 1, 1, 3, 3,3-pentafluoropropene or 1,2,3,3,3-pentafluoropropene, perfluoroalkylvinylethers and especially those of general formula Rf-O-CF = CF2, Rf being an alkyl group, preferably C1 to C4 (examples preferred being perfluoropropylvinylether or PPVE and perfluoromethylvinylether or PMVE).

In some embodiments, the X monomer has a chlorine or bromine atom. It may in particular be chosen from bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene and chlorotrifluoropropene. Chlorofluoroethylene may designate either 1-chloro-1-fluoroethylene or 1-chloro-2-fluoroethylene. The 1-chloro-1-fluoroethylene isomer (CFE) is preferred. The chlorotrifluoropropene is preferably 1-chloro-3,3,3-trifluoropropene (in cis or trans form, preferably trans) or 2-chloro-3,3,3-trifluoropropene. In certain preferred embodiments, the polymer PF comprises units derived from VDF and HFP, or is a polymer P (VDF-HFP) consisting of units derived from VDF and HFP.

Such a polymer PF is particularly useful for the manufacture of planarization or passivation layers of electronic devices.

Such a polymer PF may also be useful for the production of electroactive layers.

The molar proportion of repeating units resulting from HFP is preferably from 2 to 50%, especially from 5 to 40%.

The copolymer P (VDF-HFP) may especially be as described in the documents WO 01/32726 and US Pat. No. 6,586,547, to which reference is expressly made. In certain preferred embodiments, the PF polymer comprises units derived from VDF and CFE, or CTFE, or TFE, or TrFE, or TFE. The molar proportion of repeating units originating from monomers different from VDF is preferably less than 30%, more preferably less than 20%.

Such a polymer PF is particularly useful for the production of electroactive layers.

In some preferred embodiments, the PF polymer comprises units derived from VDF and TrFE, or is a P (VDF-TrFE) polymer consisting of units derived from VDF and TrFE.

In certain preferred embodiments, the polymer PF comprises units derived from VDF, TrFE and another monomer X as defined above, different from VDF and TrFE, or else is a polymer P (VDF-TrFE X) consisting of units derived from VDF, TrFE and another monomer X as defined above, different from VDF and TrFE. In this case, preferably, the other monomer X is chosen from TFE, HFP, trifluoropropenes and in particular 3,3,3-trifluoropropene, tetrafluoropropenes and in particular 2,3,3,3-tetrafluoropropene or 1, 3,3,3-tetrafluoropropene (in cis or preferably trans form), bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene and chlorotrifluoropropene. CTFE or CFE are particularly preferred.

When units derived from VDF and TrFE are present, the proportion of units derived from TrFE is preferably 5 to 95 mol% relative to sum of the units derived from VDF and TrFE, and in particular: from 5 to 10 mol%; or from 10 to 15 mol%; or from 15 to 20 mol%; or from 20 to 25 mol%; or from 25 to 30 mol%; or from 30 to 35 mol%; or 35 to 40 mol%; or from 40 to 45 mol%; or 45 to 50 mol%; or from 50 to 55 mol%; or from 55 to 60 mol%; or from 60 to 65 mol%; or from 65 to 70 mol%; or from 70 to 75 mol%; or from 75 to 80 mol%; or from 80 to 85 mol%; or from 85 to 90 mol%; or from 90 to 95 mol%. A range of 15 to 55 mol% is particularly preferred.

When units derived from another monomer X, in addition to VDF and TrFE, are present (the monomer X being in particular CTFE or CFE), the proportion of units derived from this other monomer X in the polymer PF (by ratio to all the units) can vary for example from 0.5 to 1 mol%; or from 1 to 2 mol%; or from 2 to 3 mol%; or from 3 to 4 mol%; or from 4 to 5 mol%; or from 5 to 6 mol%; or from 6 to 7 mol%; or from 7 to 8 mol%; or from 8 to 9 mol%; or from 9 to 10 mol%; or from 10 to 12 mol%; or from 12 to 15 mol%; or from 15 to 20 mol%; or from 20 to 25 mol%; or from 25 to 30 mol%; or from 30 to 40 mol%; or from 40 to 50 mol%. Ranges of 1 to 20 mol%, and preferably 2 to 15 mol%, are particularly suitable.

The molar composition of the units in the fluorinated polymers can be determined by various means such as infrared spectroscopy or RAMAN spectroscopy. Conventional methods for elemental analysis in carbon, fluorine and chlorine or bromine or iodine elements, such as X-ray fluorescence spectroscopy, make it possible to calculate without ambiguity the mass composition of the polymers, from which the molar composition is deduced.

Multi-core NMR techniques, especially proton (1 H) and fluorine (19F), can also be performed by analyzing a solution of the polymer in a suitable deuterated solvent. The NMR spectrum is recorded on an FT-NMR spectrometer equipped with a multi-nuclear probe. The specific signals given by the various monomers are then identified in the spectra produced according to one or the other nucleus. Thus, for example, the unit derived from TrFE gives proton NMR a specific signal characteristic of the CFH group (at about 5-7 ppm, when the solvent is pyridine for example). It is the same for the Chb groups of VDF (massive between 2 - 4 ppm, when the solvent is pyridine for example). The relative integration of the two signals gives the relative abundance of the two monomers, i.e. the VDF / TrFE molar ratio.

In the same way, the group CF3 for example gives characteristic and well isolated signals in NMR of fluorine. The combination of the relative integrations of the different signals obtained in proton NMR and in NMR fluorine leads to a system of equations whose resolution leads to obtaining molar concentrations of units from different monomers.

Finally, it is possible to combine elemental analysis, for example for heteroatoms such as chlorine or bromine or iodine, and NMR analysis. Thus, the content of units derived from CTFE in a P terpolymer (VDF-TrFE-CTFE), for example, can be determined by a measurement of the chlorine content by elemental analysis.

The skilled person thus has a range of methods or combination of methods allowing him to determine without ambiguity and with the necessary precision the composition of fluoropolymers.

The viscosity of the polymer PF is preferably from 0.1 to 100 kPo (kiloPoise) by measuring at 230 ° C. and at 100 s ^-1 shear rate (according to ASTM D4440, using a PHYSICA MCR301 equipped with two parallel trays).

The polymer PF is preferably random and linear.

The polymer PF may be homogeneous or heterogeneous. A homogeneous polymer has a uniform chain structure, the statistical distribution of the units from different monomers does not vary substantially between the chains. In a heterogeneous polymer, the chains have a distribution in units resulting from different monomers of nnultinnodale or spread type. A heterogeneous polymer therefore comprises richer chains in a given unit and poorer chains in this unit. An example of a heterogeneous polymer is disclosed in WO 2007/080338.

The PF polymer can be produced using any known method, such as emulsion polymerization, suspension polymerization and solution polymerization.

When the fluoropolymer comprises units derived from VDF and / or TrFE and another monomer X as described above, it is preferable to use the process described in WO 2010/1 16105. This process allows to obtain polymers of high molecular weight and suitable structuring.

In short, the preferred method comprises the following steps:

loading an initial mixture containing only VDF and / or TrFE (without the other monomer X) into a stirred autoclave containing water; heating the autoclave to a predetermined temperature, close to the polymerization temperature;

the injection of a radical polymerization initiator mixed with water in the autoclave, in order to reach a pressure in the autoclave which is preferably at least 80 bars, so as to form a suspension of monomers of VDF and / or TrFE in water;

injecting a second mixture of VDF and / or TrFE and X into the autoclave;

as soon as the polymerization reaction starts, the continuous injection of said second mixture into the autoclave reactor, in order to maintain the pressure at a substantially constant level, preferably of at least 80 bar.

The radical polymerization initiator may in particular be an organic peroxide of the peroxydicarbonate type. It is generally used in an amount of 0.1 to 10 grams per kilogram of the total monomer charge. Preferably, the amount used is 0.5 to 5 g / kg.

The initial mixture advantageously comprises only VDF and / or TrFE in a proportion equal to that of the desired final polymer.

The second mixture preferably has a composition which is adjusted so that the total monomer composition introduced into the autoclave, including the initial mixture and the second mixture, is equal to or approximately equal to the desired final polymer composition.

The weight ratio of the second mixture to the initial mixture is preferably 0.5 to 2, more preferably 0.8 to 1.6.

The implementation of this process with an initial mixture and a second mixture makes the process independent of the start-up phase of the reaction, which is often unpredictable. The polymers thus obtained are in the form of a powder, without rind or skin.

The pressure in the autoclave reactor is preferably 80 to

1 bar, and the temperature is maintained at a level of preferably 40 ° C to 60 ° C.

The second mixture can be injected continuously into the autoclave. It can be compressed before being injected into the autoclave, for example by using a compressor or two successive compressors, generally at a pressure higher than the pressure in the autoclave.

After synthesis, the polymer can be washed and dried. The weight average molar mass Mw of the polymer PF is preferably at least 100,000 g. mol ^"1 , preferably at least 200000 g, mol ^{" 1} and more preferably at least 300000 g. mol ^"1 or at least 400000 g mol ^{" 1} . It can be adjusted by modifying certain process parameters, such as the temperature in the reactor, or by adding a transfer agent.

The molecular weight distribution can be estimated by SEC (size exclusion chromatography) with dimethylformamide (DMF) as eluent, with a set of 3 columns of increasing porosity. The stationary phase is a styrene-DVB gel. The detection method is based on a measurement of the refractive index, and the calibration is performed with polystyrene standards. The sample is dissolved in 0.5 g / l in DMF and filtered through a 0.45 μm nylon filter. Silane agent

The silane agent has the formula S1R1 R2R3R4, wherein R1, R2, R3 and R4 are identical or different chemical groups, which are linked by single bond to the Si atom.

The silane agent may in particular be an organosilane, that is to say a compound in which at least one of the groups R 1, R 2, R 3 and R ₄ is a carbon group.

Preferably, the silane agent is not a polymer.

In some embodiments, the silane agent has a molecular weight of less than or equal to 5000 g / mol, or 2000 g / mol, or 1500 g / mol, or 1000 g / mol, or 500 g / mol or 400 g / mol, or 300 g / mol, or 200 g / mol, or 150 g / mol, or 120 g / mol.

In some embodiments, the silane agent is a siloxane, i.e. the -R ₄ moiety, for example, represents -O-S1R5R6R7. It may be an organosiloxane, when at least one of the groups R 1, R 2, R 3, R 5, R 6 and R 7 is a carbon group.

In some embodiments, the silane agent is a silazane, i.e., the -R ₄ moiety, for example, represents -NH-SiRsReRz. It may be an organosilazane, when at least one of the groups R 1, R 2, R 3, R 5, R 6 and R 7 is a carbon group.

In some embodiments, the silane agent has at least one amine, or fluorine, or vinyl, or glycidyl, or (meth) acrylic function. The amine function is particularly preferred. Such functions can allow to obtain a good compatibility between the polymer PF and the silane agent.

In some embodiments, the presence of an amine function is particularly preferred, since it can provide a particularly high improvement in substrate adhesion.

In certain embodiments, the presence of an amine or glycidyl function is particularly preferred, since it may offer an improvement in the electrical properties (remanent polarization and / or saturation polarization) of the polymer film.

In other embodiments, the silane agent is devoid of an amine function, which may in particular make it possible to avoid or limit a possible effect of discoloration (yellowing) of the polymer film.

In some embodiments:

R 1, R 2 and R 3 each independently represent a C 1 -C 4 alkoxy group, preferably a C 1 -C 3 alkoxy group, and more preferably a methoxy or ethoxy group; and

R 4 represents a C 1 -C 10, preferably C 1 -C 5, preferably C 1 -C 3, alkyl group, optionally halogenated (preferably fluorinated) in whole or in part, and optionally comprising a terminal function, which preferably is chosen; among the functions amine, (meth) acrylic, vinyl and glycidyl. Preferred silane agents include 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, fluoroalkylsilanes (especially fluoroalkyltrimethoxysilanes and fluoroalkyltriethoxysilanes) and vinyltrimethoxysilane.

Combinations of many of the above silane agents may also be used. Solvent and additives

According to the invention, the polymer (s) PF and the silane agent (s) are dissolved in a solvent. By "solution" is meant a homogeneous dispersion of the constituents in the solvent, at the molecular level. The term solution is used herein as opposed to a suspension of polymer particles in a liquid vehicle, and as opposed to an emulsion or polymer latex. The composition comprising the solvent, the PF polymer (s) and the silane agent (s) (and optionally additional compounds such as additives) is also called an ink.

Preferably, the solvent is chosen from: dimethylformamide; dimethylacetamide; dimethylsulfoxide; ketones, especially acetone, methyl ethyl ketone (or butan-2-one), methyl isobutyl ketone and cyclopentanone; furans, especially tetrahydrofuran; esters, especially methyl acetate, ethyl acetate, propyl acetate, butyl acetate and propylene glycol methyl ether; carbonates, especially dimethyl carbonate; phosphates, especially triethylphosphate. Mixtures of these compounds can also be used.

The weight proportion of polymer (s) PF relative to the sum of the polymer (s) PF and agent (s) silane (s) in the composition may be in particular: from 50 to 60%, or from 60 to 70%, or 70 to 75%, or 75 to 80%, or 80 to 85%, or 85 to 90%, or 90 to 95%, or 95 to 98%, or 98 to 99%, or 99 to 99.9%, or 99.9 to 99.99%. Conversely, the mass proportion of agent (s) silane (s) relative to the sum of the polymer (s) PF and agent (s) silane (s) in the composition may be in particular: from 0.01 to 0.1 %, or 0.1 to 1%, or 1 to 2%, or 2 to 5%, or 5 to 10%, or 10 to 15%, or 15 to 20%, or 20 to 20%, or 25%, or 25 to 30%, or 30 to 40%, or 40 to 50%. Ranges of 0.1 to 2%, and 0.2 to 1.5% of silane agent are examples of preferred ranges.

The composition preferably contains from 0.1 to 60%, preferably from 0.5 to 30%, more preferably from 1 to 20%, more preferably from 3 to 15% by weight of polymer (s) PF and agent. (s) silane (s) (together), relative to the total composition.

The ink may optionally comprise one or more additives, especially chosen from surface-tension modifiers, rheology-modifying agents, aging-modifying agents, adhesion-modifying agents, pigments or dyes. , charges (including nanofillers). Preferred additives include co-solvents modifying the surface tension of the ink. In particular, it may be organic compounds miscible with the solvents used. Examples are compounds of the family of linear or cyclic alkanes such as heptane and cyclohexane, decane or dodecane, and aromatic compounds such as toluene or ethylbenzene. The ink composition may also contain one or more additives used for the synthesis of the polymer (s).

In certain embodiments in which it is desired to crosslink the polymers after deposition of the composition, the ink comprises at least one crosslinking aid additive preferably chosen from radical initiators, co-agents such as bifunctional molecules. or polyfunctional in terms of reactive double bonds, basic crosslinking agents such as di-amines, and combinations thereof.

In particular, a photoinitiator may be used, for example chosen from 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyl-diphenylphosphineoxide, 2,4, 6-trimethylbenzoylphenyl phosphinate, 1-hydroxy-cyclohexyl-phenyl-ketone, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentyl phosphine oxide, 1- [4- (2-hydroxyethoxy) - phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-methyl-1 [4- (methylthio) phenyl] Morpholinopropan-1-one, 2,4-diethylthioxanthone, their derivatives, and mixtures thereof.

In particular, it is possible to use a crosslinking agent chosen from bi- or polyfunctional (meth) acrylic monomers or oligomers in terms of reactive double bonds. These bi- or polyfunctional (meth) acrylic monomers or oligomers may have chemical structures derived from functions other than the strict alkane chemistry, such as diols, triols or polyols, polyesters, ethers, polyethers, polyurethanes, epoxys, cyanurates or isocyanates. cyanurates. Examples which may be mentioned are: 1,3-butylene glycol di (meth) acrylate, butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, hexane diol alkoxylated di (meth) acrylate, neopentyl glycol alkoxylated di (meth) acrylate, dodecyl di (meth) acrylate, cyclohexane dimethanol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, linear alkanes di ( meth) acrylates, bisphenol A ethoxylated di (meth) acrylate, ethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tricyclodecane dimethanol diacrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol ethoxylated tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, penta (meth) acrylate ester, pentaerythritol tetra (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, trimethylolpropane alkoxylated tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane propoxylated tri (meth) acrylate, trimethylolpropane trimethacrylate, dodecanediol di (meth) acrylate, dodecane di (meth) acrylate, dipentaerythritol penta / hexa (meth) acrylate, pentaerythritol tetra (meth) ) acrylate, di-trimethylolpropane tetra (meth) acrylate, glyceryl propoxylated tri (meth) acrylate, glyceryl propoxylated tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, polyesters (meth) acrylates, polyethers (meth) acrylates, polyethylene glycols (meth) acrylates, polypropylenes glycol (meth) acrylates, polyurethanes (meth) acrylates, epoxy (meth) acrylates and combinations thereof.

In other (preferred) embodiments, no crosslinking aid additive, such as a photoinitiator or a crosslinking agent, is present in the ink.

The total content of additives is preferably less than 20% by weight, more preferably less than 10% by weight, based on the total of polymer (s) PF, agent (s) silane (s) and additives.

The ink preferably has a nonvolatile solids content of 0.1 to 60%, preferably 0.5 to 30%, more preferably 1 to 20%, more preferably 3 to 15% by weight. .

Preparation of the composition

The ink composition according to the invention can be prepared by dissolving the PF polymer in the solvent, and mixing with the silane agent.

The temperature applied during this preparation is preferably 0 to 120 ° C, more preferably 10 to 100 ° C, more preferably 15 to 80 ° C, and most preferably 20 to 70 ° C. In some embodiments, the preparation is performed at room temperature. In other embodiments, the preparation is carried out in the presence of heating, preferably at a temperature of 40 to 100 ° C, more preferably of 50 to 80 ° C. Advantageously, the preparation is carried out with moderate agitation.

In some embodiments, the silane agent is dissolved in the solvent on one side (or directly supplied as a solution in the solvent), and the PF polymer is dissolved in the same solvent on the other side, and then both solutions. are mixed. The solvent used may be formed by a single compound or a mixture of compounds miscible with each other.

In other embodiments, one of the silane agent and the PF polymer is dissolved in the solvent, then the other of the silane agent and the PF polymer is added to the solution and dissolved in turn. The solvent used may be formed by a single compound or a mixture of compounds miscible with each other.

In still other embodiments, the solvent of the ink composition is a mixture of a first solvent and a second solvent of different compositions and miscible with each other. The silane agent is dissolved in the first solvent to form a first solution (or a first solution is directly supplied, comprising the silane agent in the first solvent), the PF polymer is dissolved in the second solvent to form a second solution, then the first solution and the second solution are mixed to form the ink composition of the invention. The first solvent and the second solvent may each be formed by a single compound or a mixture of compounds miscible with each other. For example, the first solvent and the second solvent may each be formed by mixtures of the same compounds, in different proportions between the first solvent and the second solvent.

When additives must be added to form the ink composition of the invention, they may be added before, during or after the dissolution of the silane agent and the polymer PF and / or the mixture thereof .

The miscibility of solvent compounds with each other, or of solvents between them, is verified by obtaining a transparent and homogeneous solution after mixing, at the preparation temperature which is used (and preferably at room temperature).

In some simpler and therefore preferred embodiments, the silane agent is a liquid at room temperature. The ink composition according to the invention can then be prepared according to a simplified method by dissolving the polymer PF in the solvent, diluting the silane agent and the solvent, and mixing them; or by directly adding the silane agent into a solution of the PF polymer in the solvent; or dissolving the PF polymer in the solvent in which the silane agent has been previously diluted.

Using the composition

The substrate on which the ink is deposited may in particular be a surface of glass, or of silicon, or of quartz, or of polymeric material (in particular polyethylene terephthalate or polyethylene naphthalate), or of metal, or a mixed surface composed of several materials different.

In some preferred embodiments, the substrate is or comprises a metal surface. In certain preferred embodiments, the substrate is or comprises a surface comprising -MOH-type functions, M representing a metal atom that can be in particular gold, silver, chromium, aluminum or copper.

In certain preferred embodiments, the substrate is or comprises a surface comprising silanol functions -SiOH, and in particular a surface of glass or silicon.

The application of the ink may comprise spreading by discrete or continuous means. The deposition may be carried out in particular by coating by centrifugation ("spin-coating"), by spraying or atomizing ("spray coating"), by coating, in particular with a bar or a film puller ("bar coating"), by coating with slit, dip coating, roll-to-roll printing, screen printing, flexographic printing, lithographic printing or jet printing ink.

The solvent is evaporated after the deposition. The polymer layer then solidifies to form a continuous film, by interdiffusion of the polymer molecules. The evaporation can be carried out at room temperature and / or by heating at a temperature preferably from 30 to 200 ° C, more preferably from 50 to 180 ° C, more preferably from 80 to 160 ° C. The layer may be vented to facilitate evaporation. The duration of the evaporation can be, for example, from 1 minute to 24 hours, preferably from 5 minutes to 5 hours, more preferably from 10 minutes to 2 hours.

An annealing step may be carried out after evaporation of the solvent, for example to allow crystallization of the polymer. The annealing may in particular be carried out by subjecting the deposited layer to a temperature of 50 to 200 ° C., preferably of 80 to 180 ° C., more preferably of 100 to 160 ° C., in particular of 120 to 150 ° C.

The fluoropolymer layer thus formed may have in particular a thickness of 50 nm to 100 μm, preferably 200 nm to 50 μm, and more preferably 500 nm to 20 μm.

According to a variant of the invention, a crosslinking step can be carried out by subjecting the layer to radiation, such as X, gamma, UV radiation or by thermal activation if the annealing step is not sufficient. Preferably, UV irradiation is used. Preferably, all or part of the radiation having a wavelength in a spectral range of 150 to 410 nm, preferably 315 to 410 nm. Of Preferably, the irradiation comprises wavelengths at 365 nm and / or 385 nm and / or 405 nm. More preferably, the dose of radiation applied is less than 20 J / cm ² , or even less than 10 J / cm ² .

The film according to the invention can be used as an electroactive layer and / or as a dielectric layer in an electronic device, and in particular when the polymer PF is a P (VDF-TrFE) or P (VDF-TrFE) copolymer -CFE) or P (VDF-TrFE-CTFE) as described above. The film according to the invention thus advantageously has a dielectric permittivity at 25 ° C. and 1 kHz greater than 8, preferably greater than 10 and more particularly greater than 12. The film advantageously also has a saturation polarization greater than 30 mC / m. ² , preferably greater than 50 mC / m ² .

The dielectric permittivity measurement can be carried out by means of a LCF meter Sefelec LCR 819, which makes it possible to measure a capacitance which is proportional to the permittivity.

The saturation polarization can be obtained by applying an alternating electric field of increasing amplitude and a frequency of 50 mHz by means of electrodes on a surface of 1 mm ² of the film. The current passing through the sample is measured as a function of the electric field applied via a precision ammeter. The current measurement provides access to the saturation polarization.

One or more additional layers may be deposited on the substrate provided with the film of the invention, for example one or more layers of polymers, semiconductor materials, or metals, in a manner known per se.

The term electronic device is either a single electronic component or a set of electronic components, capable (s) to perform one or more functions in an electronic circuit.

According to certain variations, the electronic device is more particularly an optoelectronic device, that is to say capable of emitting, detecting or controlling electromagnetic radiation.

Examples of electronic devices, or possibly optoelectronic devices, concerned by the present invention are transistors (in particular field effect), chips, batteries, photovoltaic cells, light-emitting diodes (LEDs), organic light-emitting diodes ( OLED), sensors, actuators, transformers, haptic devices, electromechanical microsystems and detectors. Electronic and optoelectronic devices are used and integrated in many electronic devices, equipment or subassemblies and in many objects and applications such as televisions, mobile phones, rigid or flexible screens, thin-film photovoltaic modules, lighting sources, energy sensors and converters, etc.

Alternatively, the layer may be used as a protective coating (or encapsulation) for an electronic device, and especially when the polymer PF is a P copolymer (VDF-HFP) as described above. Such a protective coating may be used alone or in combination with other protective films.

In this case, the electronic device may in particular comprise a substrate and electronic elements supported on it, which may comprise layers of conductive material, semiconductor material and the like. The electronic elements are preferably on one side of the substrate but in some embodiments they may be on both sides of the substrate. The layer may cover all or part of the electronic elements, and all or part of the substrate. Preferably, the layer covers at least a portion of the substrate and at least a portion of the electronic elements, and performs a planarizing function. The layer may cover only one of the two faces of the substrate (preferably the face which comprises the electronic elements), in whole or in part, or alternately the two faces of the substrate, in whole or in part.

When the layer is used as a protective coating for an electronic device, the electronic device may be of the same type as above.

EXAMPLES

The following examples illustrate the invention without limiting it.

Examples 1-5 (Invention)

In a stirred glass reactor with a jacket in which circulates a heat transfer fluid for heating the reactor contents and optionally cooling and also provided with a vapor condensation system (reflux) with the aid of a refrigerant cooled with water, and a nitrogen sparge system is introduced 128.43 g of methyl ethyl ketone (MEK), 17.98 g of an electroactive fluorinated copolymer of relative molar composition determined by spectroscopy magnetic resonance 80 ± 2% nuclear (NMR) units derived from VDF and 20 ± 2% TrFE derived units and some silane agent mass. The tested agents are:

- Example 1: 3-aminopropyltriethoxysilane (Dynasylan® AMEO), in an amount of 0.7% by weight relative to the sum of the silane agent and the fluorinated copolymer;

Example 2: 3-glycidyloxypropyltriethoxysilane (Dynasylan® GLYEO), in an amount of 1.0% by weight, based on the sum of the silane agent and the fluorinated copolymer;

Example 3: Fluoroalkylsilane (Dynasylan® F8261), in an amount of 1.0% by weight based on the sum of the silane agent and the fluorinated copolymer;

Example 4: 3-glycidyloxypropyltrimethoxysilane (Dynasylan® GLYMO), in an amount of 1.0% by weight based on the sum of the silane agent and the fluorinated copolymer;

Example 5: vinyltrimethoxysilane (Dynasylan® VTMO), in an amount of 1.0% by weight, based on the sum of the silane agent and the fluorinated copolymer.

The preparation of the solution is continued by gentle stirring at 80 ° C. under reflux until the two compounds initially added have been completely dissolved.

Polymer films are prepared by coating with a bar of a glass plate from the above solutions. The glass plate is deposited in a ventilated grid, at room temperature, for 30 minutes, to allow at least partial evaporation of the solvent. It is then placed 20 minutes in a ventilated oven previously heated to 80 ° C to allow total evaporation of the solvent, then at 135 ° C to allow crystallization of the deposited film.

Example 6 (comparative)

In Example 6, an ink is made and a polymer layer is deposited in the same manner as in the previous examples, but omitting the silane agent.

Example 7 - characterization

The polymer layers according to Examples 1 to 6, 60 μιτι approximately, are tested as follows. The adhesion properties of the layer on the glass plate are evaluated according to the ASTM D3359 ("tape test") test, using an ERICHSEN Model 259 grid comb.

The notation in this test has the following meaning:

- Note 0: cut edges completely smooth, without splinters. No loss of coating.

- Note 1: slight spalling at points of intersection, with a loss of cladding that is not significantly greater than 5% over the total area of the grid.

- Note 2: flaking along cut edges and / or at points of intersection, with a coating loss that is significantly greater than 5% but not significantly greater than 15% of the total area.

- Note 3: chipping along cut edges and / or squares, with a coating loss that is significantly greater than 15% but not significantly greater than 35% of the total area.

- Note 4: chipping along cut edges and / or squares, with a coating loss that is significantly greater than 35% but not significantly greater than 65% of the total area.

- Note 5: peeling with a coating loss that is significantly greater than 65% of the total area.

The electro-activity of the films is evaluated by polarization of the film giving access to the values of coercive field (Ec), remanent polarization (P _r ), and saturation polarization (Psat). An alternating electric field of increasing amplitude and a frequency of 50 mHz is applied through the electrodes to a surface of 1 mm ² of the film. The current passing through the sample is measured as a function of the electric field applied via a precision ammeter.

The results are summarized in the table below.

Surface of

Ec Pr Psat Adhesion coating

lost

Ex. 6 (comparative) 43.3 81, 3 83.3 5> 90%

Ex. 1 (invention) 41, 84.0 84.9 1 <5% Ex. 2 (Invention) 45.0 87.1 87.8 4 65%

Ex. 3 (Invention) 44.7 81.8 82.5 5 35%

Ex. 4 (invention) n.e. nr. 5 5 80%

Ex. 5 (invention) n.e. n.d. 5 5 64%

In all cases, there is an improvement in the adhesion without degradation of the electroactive properties, or even a slight improvement thereof. The efficiency is particularly remarkable with the AMEO.

Claims

Composition comprising:

a PF polymer comprising units derived from vinylidene fluoride and units derived from trifluoroethylene; and

- a silane agent of formula S1R1 R2R3R4, wherein Ri, R2, R3 and R ₄ are chemical moieties linked by single bond to the Si atom;

in solution in a solvent.

The composition of claim 1, wherein the PF polymer also comprises units derived from at least one other monomer of formula CXiX2 = CX3X4 wherein each group X1, X2, X3 and X ₄ is independently selected from H, Cl , F, Br, I and alkyl groups comprising from 1 to 3 carbon atoms, which are optionally partially or fully halogenated; and preferably the polymer PF comprises units derived from at least one monomer chosen from trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, 1,1-chlorofluoroethylene, hexafluoropropene, 3,3,3-trifluoropropene, 1, 3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoropropene and 2-chloro-3,3,3-trifluoropropene.

The composition of claim 1 or 2, wherein the PF polymer comprises from 15 to 55 mol. % of trifluoroethylene units relative to the sum of the units derived from vinylidene fluoride and trifluoroethylene.

Composition according to one of claims 1 to 3, wherein the polymer PF further comprises units derived from an additional monomer, said additional monomer being preferably chlorotrifluoroethylene or 1,1-chlorofluoroethylene, and the proportion of units the additional monomer is preferably 1 to 20 mol%, more preferably 2 to 15 mol%, based on all the units of the polymer PF. Composition according to one of Claims 1 to 4, in which the polymer PF comprises units derived from hexafluoropropene, preferably in a proportion of 2 to 50 mol%, more preferably 5 to 40 mol%, by weight. compared to all the units of the polymer PF.

Composition according to one of claims 1 to 5, wherein the silane agent has a molecular weight less than or equal to 2000 g / mol, preferably less than or equal to 1000 g / mol, more preferably less than or equal to 500 g mol, and more particularly less than or equal to 200 g / mol.

Composition according to one of Claims 1 to 6, in which:

the silane agent is a silazane.

Composition according to one of claims 1 to 7, wherein the silane agent is chosen from 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, fluoroalkylsilanes, vinyltrimethoxysilane and combinations thereof.

Composition according to one of Claims 1 to 8, in which the polymer PF is present in a proportion of 70 to 99.99% by weight, and preferably in a proportion by weight of 80 to 99.8% by weight; and the silane agent is present in a proportion of 0.01 to 30% by weight, and preferably 0.2 to 20% by weight; the proportions being given with respect to the sum of the polymer PF and the silane agent.

Composition according to one of Claims 1 to 9, in which the solvent is chosen from dimethylformamide, dimethylacetamide, dimethylsulfoxide and ketones. in particular acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclopentanone, furans, especially tetrahydrofuran; esters, in particular methyl acetate, ethyl acetate, propyl acetate, butyl acetate and propylene glycol methyl ether, carbonates, especially dimethyl carbonate, phosphates, especially triethylphosphate, and mixtures thereof.

11. Process for preparing a composition according to one of claims 1 to 10, comprising dissolving the polymer PF in the solvent, providing the silane agent, and mixing them.

12. A method of manufacturing a polymer film, comprising depositing the composition according to one of claims 1 to 10 on a substrate, and evaporation of the solvent from the composition.

An electronic device comprising a substrate coated with a polymer film manufactured according to the method of claim 12.

An electronic device according to claim 13, wherein the polymer film is an electroactive polymer film; or wherein the polymeric film is a protective film. 15. An electronic device according to claim 13 or 14, which is an optoelectronic device and / or which is chosen from transistors, in particular field-effect, chips, batteries, photovoltaic cells, light-emitting diodes, in particular light-emitting diodes. sensors, actuators, transformers, haptic devices, electromechanical microsystems and detectors.

16. Use of a silane agent of formula S1R1 R2R3R4, wherein Ri, R2, R3 and R ₄ are chemical moieties linked by single bond to the Si atom, to improve adhesion of a polymer comprising units PF from vinylidene fluoride and units from trifluoroethylene on a substrate. Use according to claim 16, wherein the silane agent and the polymer PF are as described in one of claims 2 to 10.

Use of a silane agent of formula S1R1 R2R3R4, wherein Ri, R2, R3 and R ₄ are chemical moieties linked by single bond to the Si atom, to improve the saturation polarization and / or the remanent polarization of a film comprising a polymer PF comprising units derived from vinylidene fluoride and units derived from trifluoroethylene.

Use according to claim 18, wherein the silane agent and the PF polymer are as described in one of claims 2 to 10.