WO2019077228A1

WO2019077228A1 - Pulverulent crosslinkable coating composition

Info

Publication number: WO2019077228A1
Application number: PCT/FR2018/052500
Authority: WO
Inventors: Jean-Marc Corpart; René SAINT-LOUP
Original assignee: Roquette Freres
Priority date: 2017-10-16
Filing date: 2018-10-09
Publication date: 2019-04-25
Also published as: FR3072388B1; FR3072388A1

Abstract

The invention concerns a pulverulent crosslinkable coating composition comprising a curing agent and an oligocarbonate polyol devoid of aromatic groups and phenolic functions, said oligocarbonate polyol being obtainable by a process comprising a step of polycondensation by transesterification of monomers (A1) and/or dimers (A2) and of diol monomers (B1) and/or triol monomers (B2), in a particular molar ratio, to obtain an oligocarbonate polyol having a molar mass of less than 5000 g/mol and at least two hydroxyl chain ends, wherein the monomer (A1) formula (I) corresponds to the following formula: (A1) and the dimer (A2) corresponds to the following formula: (formula 2), and also a process for manufacturing a coating on a substrate by depositing and then crosslinking a layer of the crosslinkable coating composition on this substrate, and said polymeric coating.

Description

CROSS-LINKABLE PULVERULENT COATING COMPOSITION

The present invention relates to the field of polymeric coatings.

In particular, the invention relates to a crosslinkable powder coating composition which employs novel oligocarbonate polyols obtained by reaction between a dianhydrohexitol dialkylcarbonate and / or a dianhydrohexitol carbonate dimer and another diol and / or triol in particular reaction conditions and in particular relative amounts of the species involved.

It has the advantage of using a dianhydrohexitol, whose bio-sourced origin reduces the fossil footprint of the manufactured product, not to use phosgene or to generate phenol like many previous solutions, these two products being dangerous. for the user but also proscribed for any application with food contact, lead to products with controlled architecture, and finally to allow with these products the manufacture of particularly resistant to abrasion, scratches and UV coatings.

The poly- or oligocarbonates diols are currently well known species, and find many applications in the manufacture of adhesives but also various coatings such as paints, lacquers and varnishes. One of their well-known applications is the manufacture of coatings such as polyurethane resins. As well as ether components (polytetramethylene glycol), esters (from adipate in particular), polylactone (polycaprolactone base among others), polycarbonate diols are one of the starting raw materials of these polyurethane resins.

If the ethers have good resistance to hydrolysis, they are less so with respect to light and heat. The esters exhibit diametrically opposite behavior with respect to these same properties. As for polycaprolactones, they are also deficient with regard to hydrolysis phenomena. It is therefore recognized that polycarbonates diols present to date the best compromise in order to obtain a durable quality for the final product, in terms of resistance to hydrolysis, heat and light. This is particularly important for a polyurethane coating, especially in applications such as exterior paints which are precisely exposed to the aforementioned constraints.

The manufacture of polyurethane-type materials based on polycarbonate polyols is now well described in the literature. By way of example, the document WO 2015/026613 discloses a piston seal for a hydraulic pump, said seal being of polyurethane type and obtained by reaction between a polycarbonate-isocyanate prepolymer, a polycarbonate polyol, a diol and a hardening agent. As for oligocarbonates diols, their synthesis is also well-known in the prior art. These products are prepared from aliphatic polyols which react with phosgene, bischlorocarbon esters, diaryl carbonates, these cyclic carbonates or dialkyl carbonates. In this regard, reference may be made to US 2005 065360.

This being the case, whilst seeking to guarantee an excellent level of performance for the poly- or oligocarbonates diols it manufactures, the person skilled in the art must today incorporate new constraints, particularly of an environmental nature. The development of polymeric materials derived from renewable resources in the short term has indeed become a major ecological and economic imperative, faced with the depletion and rising prices of fossil resources such as oil. In this context, the use of dianhydrohexitols, derived from plant (poly) saccharides, as dihydroxy monomers in polycondensation reactions, appears promising to replace monomers of petrochemical origin.

Some attempts have been made to make polycarbonate diols incorporating dianhydrohexitols. As such, documents JP2014-62202 and JP 2014-80590 are known. The first describes a composition comprising a phosphorus compound, a phenolic compound and a polycarbonate diol, the latter having a number-average molecular weight of between 250 and 5,000 and having a molar ratio of hydroxyl groups and terminal groups of at least 95%. . The second describes a polycarbonate diol consisting of a diol and a dianhydrohexitol selected from isosorbide, isomannide and isoidide, and having a weight average molecular weight of between 250 and 5,000 as determined by NMR, while by having a ratio in number of alkyloxy or aryloxy terminal groups relative to the total number of end groups greater than or equal to 5%.

Nevertheless, these products are obtained by reaction between a diol and dianhydrohexitol, but also in the presence of diphenyl carbonate. Phenol is therefore generated during the synthesis of the polycarbonate diol. Now, phenol is a product that is both dangerous for the user - at the level of the product, and that of the final application and proscribed for applications with food contact. The presence of phenol is therefore prohibitive: it must be distilled and then removed. This is demonstrated by the tests illustrating the 2 patent applications mentioned above.

Also known is EP 2 559 718 which describes the simultaneous reaction between a diol selected from isosorbide, isomannide and isoidide, another diol, and a diester carbonate, such as diphenyl carbonate. Thus, a polycarbonate diol is obtained here, but with a completely statistical architecture because the diester carbonate is very reactive, it reacts without preference with both the dianhydrohexitol and the other diol. The final properties of the product, such as its resistance to hydrolysis, light and heat being directly related to its architecture, said polycarbonate diol will have fluctuating properties depending on its final architecture. This lack of control of the level of properties can not accommodate an industrial use for the product in question.

Also, in order to manufacture oligocarbonates polyols advantageously implementing a naturally occurring monomer such as a dianhydrohexitol and without using phosgene and without generating phenol during the reaction, and finally while allowing itself to regulate From the architecture of the synthesized product, the applicant company has been able to develop the following process, consisting in reacting a dialkyl carbonate of dianhydrohexitol and / or a dimer of dianhydrohexitol carbonate with another diol and / or triol, to obtain oligocarbonates polyols. presenting an alternating architecture perfectly controllable and controlled. A molar excess of the other diol and / or triol relative to the dialkyl carbonate of dianhydrohexitol and / or a dianhydrohexitol carbonate dimer makes it possible to obtain hydroxyl terminations. In doing so, we are able to solve the technical constraints mentioned above. Moreover, in the end, diol polycarbonates, which can be used in the manufacture of adhesives, are obtained from various coatings such as paints, lacquers and varnishes. These oligocarbonates polyols may in particular be used to produce polyurethane resins, with particularly advantageous properties, in terms of resistance to abrasion, scratching and UV.

Advantageously, the dialkycarbonates of isosorbide which come into play in the reaction are manufactured according to the method described in the patent application WO 201 1/039483. This comprises reacting at least one dianhydrohexitol, at least 2 molar equivalents of a di (alkyl) carbonate and a transesterification catalyst. Unlike the methods described in the prior art, this method does not generate compounds harmful to humans or dangerous for the environment. So the demand for EP 2 033 981 described a synthesis whose disadvantage was the formation of phenol, which then had to be distilled and removed as a reaction by-product. As for documents US 2004/241553 and JP 06-261774, they relied on the use of toxic chloroformic esters.

summary

Also, according to a first aspect, the present invention relates to a crosslinkable powder coating composition comprising a hardener and an oligocarbonate polyol devoid of aromatic groups and phenolic functions, said oligocarbonate polyol being obtainable by a process comprising:

A step (1) of introduction into a reactor:

a monomer of formula (A1):

in which R 1 and R ₂ are identical or different alkyl groups, or a dimer of formula (A2):

wherein R ₃ and R ₄ are the same or different alkyl groups, or a mixture of (A1) and (A2); ^■ a step (2) introducing into the reactor a monomer diol (B1) or a triol monomer (B2) or a mixture of (B1) and (B2), (B1) and ( B2) being both different from (A1) and (A2); the molar ratio in the reactor of (A1) and (A2) with respect to (B1) and (B2) corresponding to the following formula:

^■ a step (3) subsequent polycondensation by transesterification of the monomers and dimers (A1), (A2), (B1) and (B2) to obtain a oligocarbonate solid polyol having a molecular weight less than 5000 g / mol and at least two hydroxyl chain terminations,

^■ a step (4) for recovering the oligocarbonate polyol.

According to a second aspect, the invention relates to a method of manufacturing a coating on a substrate comprising the following steps:

(1) The deposition on the substrate of a layer of the crosslinkable coating composition according to the inventioon, then

(2) Crosslinking of the layer applied in step (1).

According to a third aspect, the invention relates to a polymeric coating obtainable by the process for producing a coating on a substrate according to the invention.

detailed description

By "oligocarbonate polyol" according to the present invention is meant any polymer comprising repeating units, formed by the reaction of monomers or dimers, linked by carbonate bonds and in particular the repeating units described above and whose chain terminations are hydroxyl functions. These repeating units are formed by reaction of the monomer (A1) and / or the dimer (A2) with the monomers (B1) and / or (B2) already presented above. For the purpose of the present invention, the expression "a monomer" extends to mixtures of this monomer. In other words, the expression "a monomer (A1)" or "a monomer of formula (A1)" means that only one monomer of formula (A1) is used or that a mixture of different monomers of formula (A1) is used. A similar meaning is given to the terms "a monomer (A2)" or "a dimer of formula (A2)", "a monomer (B1)" or "a monomer of formula (B1)", or "a monomer (B2 ) "Or" a monomer of formula (B2) ".

As explained above, the invention relates to a process for producing hydroxytelechelic oligocarbonates by polycondensation of the monomer (A1) and / or dimer (A2) and monomers (B1) and / or (B2).

The term "1,4-3,6-dianhydrohexitol" or "dianhydrohexitol" as used in the present invention includes isosorbide (obtained by dehydration of D-glucitol), isomannide (obtained by dehydration of D-mannitol). and isoidide (obtained by dehydration of D-iditol).

By "dianhydrohexitol carbonate dimer" according to the present invention is meant a compound of formula (A2), that is to say consisting of two molecules of dianhydrohexitol monoalkylcarbonate interconnected by a bivalent carbonate function. The compound thus comprises in total two carbonate termini.

Monomers (AD and (A2)

The monomer (A1) used in step (1) may be chosen from isosorbide dialkylcarbonate, isomannide dialkylcarbonate and isoidide dialkylcarbonate.

The monomer (A1) may contain one or more dianhydrohexitol dialkylcarbonates but preferably contains a single dianhydrohexitol dialkylcarbonate, in particular an isosorbide dialkylcarbonate, available in greater quantity and at a lower cost than the other two stereoisomers.

The alkyl groups R 1 and R ₂ borne by the monomer (A 1) can comprise from 1 to 10 carbon atoms, in particular from 1 to 6 carbon atoms, for example from 1 to 4 carbon atoms, and are particularly chosen from methyl or ethyl groups.

According to one embodiment, the monomer (A1) is an isosorbide dialkylcarbonate, in particular an isosorbide diethyl carbonate or an isosorbide dimethyl carbonate.

The monomer (A1) can be obtained using, for example, already known processes for the manufacture of dianhydrohexitol dialkylcarbonate. Advantageously, the monomer (A1) is prepared according to the process described in the patent application WO 201 1/039483 (in the name of Roquette Frères) by reacting a dianhydrohexitol with at least 2 molar equivalents of a di (alkyl) carbonate. ) and a transesterification catalyst. The formation of dimers can be inhibited by the use of a large excess of dialkyl carbonate. This method has the advantage of not generating compounds harmful to humans or dangerous for the environment.

It is also possible to manufacture the monomer (A1) by reaction of dianhydrohexitol and of alkyl chloroformate, these reactants being introduced into a reactor in molar proportions of 1: 2. This type of process is described, for example, in JP 06- 261774 in Example 5. The Applicant has found that, according to this process, it forms only dialkylcarbonate dianhydrohexitol and no dimer.

The dimer (A2) used in step (1) is a dimer of (A1). Depending on the dianhydrohexitol used, one or more conformations of dimers (A2) can be obtained.

The dimer (A2) may be selected from an isosorbide carbonate dimer, an isomannide carbonate dimer, or an isoidide carbonate dimer.

The dimer (A2) may contain one or more dimers of dianhydrohexitol carbonate but preferably contains a single dianhydrohexitol carbonate dimer, in particular an isosorbide carbonate dimer, available in greater quantity and at a lower cost than both. other stereoisomers.

The alkyl groups R ₃ and R ₄ carried by the dimer (A2) can comprise from 1 to 10 carbon atoms, in particular from 1 to 6 carbon atoms, for example from 1 to 4 carbon atoms, more particularly are chosen from methyl or ethyl groups.

According to one embodiment, the dimer (A2) is an isosorbide carbonate dimer, in particular an isosorbide ethylcarbonate dimer or an isosorbide methylcarbonate dimer.

The dimer (A2) can be produced by reacting, for example in a first step, one mole of dianhydrohexitol with one mole of alkyl chloroformate in order to form dianhydrohexitol monoalkylcarbonate, then in a second step one mole of phosgene with two moles of dianhydrohexitol monoalkylcarbonate formed in the first step.

Another possibility of manufacturing the monomer (A1) and the dimer (A2) is to use a process allowing their simultaneous synthesis. Indeed, the Claimant has also to the point a method for making such a mixture. This process is described in detail in International Application No. WO201 1/039483.

This preparation method comprises, in the order, the following steps:

(a) preparing an initial reaction mixture containing:

at least one dianhydrohexitol,

at least 2 molar equivalents, relative to the amount of dianhydrohexitol present, of at least one dialkyl carbonate, and

a transesterification catalyst such as, for example, potassium carbonate, (b) heating the reaction mixture to a temperature greater than or equal to the boiling temperature of the R-OH alcohol formed by the transesterification reaction, or greater or equal to the boiling temperature of the azeotropic mixture that forms the alcohol R-OH obtained with another of the components present in the reaction mixture, and at most equal to the boiling temperature of the reaction mixture, in a reactor equipped with a rectification column comprising a number of theoretical distillation plates sufficient to separate from the reaction mixture the alcohol obtained, or the azeotrope it forms with another of the components present in the reaction mixture.

The solution obtained at the end of the process comprises a mixture of monomer (A1) and dimer (A2) with dialkyl carbonate. Distillation is carried out and the mixture of (A1) and (A2) free of dialkyl carbonate is recovered. The ratio (A1) / (A2) can be varied by modifying the initial reaction mixture: it advantageously contains from 2.1 to 100 molar equivalents, preferably from 5 to 60 molar equivalents, and in particular from 10 to 40 molar equivalents. molar equivalents of dialkyl carbonate, based on the amount of dianhydrohexitol initially present in the reaction medium. The higher the amount of dialkyl carbonate, the higher the ratio (A1) / (A2).

For example, the Applicant has found that by reacting isosorbide and dimethyl carbonate in the presence of potassium carbonate under the conditions of the method described above, a solution comprising (A1) and (A2) could be obtained. with a ratio (A1) / (A2) ranging from about 4 (when the ratio of dialkyl carbonate / isosorbide is 10) to about 20 (when the ratio of dialkyl carbonate / isosorbide is 40).

It is then possible to separate (A1) and (A2) by vacuum distillation techniques, for example using a scraped film evaporator.

This method of simultaneous synthesis of (A1) and (A2) has the advantages of using less toxic reagents than the alkyl chloroformate used in the process described in JP 06-261774 for example; co-products of synthesis are also less toxic that the chlorinated species emitted during the synthesis with chloroformate (methanol in the case where the alkyl is a methyl, ethanol in the case where the alkyl is an ethyl).

According to one embodiment, only the monomer (A1) is synthesized. Only this is introduced into the reactor in step (1), that is to say that dimer (A2) is not introduced into the reactor.

According to another embodiment, a mixture of monomer (A1) and dimer (A2) is synthesized. This mixture is introduced into the reactor in step (1). Monomers (B1) and (B2)

The diol monomer (B1) and the triol monomer (B2) may be chosen from aliphatic diols or triols, in particular linear or branched, or cyclic diols or triols, aromatic or nonaromatic. In one embodiment, the diol (B1) or triol (B2) comprises from 2 to 14 carbons.

The linear aliphatic diol (without branching) can be chosen from the following diols: ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1 10-decanediol, preferably ethylene glycol, 1,4-butanediol or 1,6-hexanediol. The linear aliphatic triol may be chosen from the following triols: glycerol, 1,2,4-trihydroxybutane, 1, 2,5-trihydroxypentane or 1,2,6-trihydroxyhexane.

The branched aliphatic diol (with unreactive pendent chains) may be chosen from the following diols: 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, 1,3-pentanediol, 1,4 hexanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol or 2-methyl-1,3-propanediol.

The cyclic diol or triol may comprise one or more rings, for example from 2 to 4 rings, preferably 2 rings. Each cycle preferably comprises from 4 to 10 atoms. The atoms included in the rings can be chosen from carbon, oxygen, nitrogen or sulfur. Preferably, the constituent atoms of the ring are carbon or carbon and oxygen.

The aromatic diol preferably comprises from 6 to 24 carbon atoms. The non-aromatic cyclic diol may comprise from 4 to 24 carbon atoms, preferably from 6 to 20 carbon atoms.

The cyclic aliphatic diol may be chosen in particular from the following diols:

^■ dianhydrohexitols such as isosorbide, isomannide and isoidide, which are heterocyclic diols biosourcés;

^■ the cyclohexanedimethanols such as 1, 2-cyclohexanedimethanol, 1, 3- cyclohexanedimethanol, and 1, 4-cyclohexanedimethanol;

^■ the tricyclodécanediméthanols;

^■ pentacyclopentanedimethanols;

Decindindimethanols such as 2,6-decalindimethanol, 1,5-decindindimethanol and 2,3-decindindimethanol;

^■ the norbornanediméthanols such as 2,3-norbornanediméthanol and norbornanediméthanol 2,5;

^■ the adamantanediméthanols such as 1, 3-adamantanediméthanol;

Cyclohexanediols such as 1, 2-cyclohexanediol, 1,3-cyclohexanediol and 1,4-cyclohexanediol;

^■ tricyclodecanediols;

^■ pentacyclopentadecanediols;

^■ decalindiols;

■ norbornanediols;

^■ adamantanediols,

^■ spiroglycol;

^■ 2,2,4,4-tetramethyl-1, 3-cyclobutanediol,

^■ Di-O-methylene-D-glucitol and dimethyl-di-O-methylene-D-glucarate.

The aromatic cyclic diol may be chosen in particular from the following diols:

^■ 1,4-Benzenedimethanol,

^■ 1,3 benzene dimethanol,

^■ 1,5 benzene dimethanol,

■ 2.5 furan dimethanol,

^■ Naphthalene-2,6-dicarboxylate.

The aromatic cyclic triol may be chosen from the following triols: pyrogallol, hydroxyquinol, phloroglucinol. Monomers other than (A1), (A2), (B1) and (B2) can be introduced according to the process of the invention.

For example, monomers comprising more than 2 alcohol or alkyl carbonate functions may be introduced. It is also possible to introduce monomers comprising several functional groups chosen from the carboxylic acid, carboxylic acid ester or amine function or mixtures of these functions. It is also possible to introduce other monomers such as dianhydrohexitol monoalkylcarbonate, oligomers of (A1) with a degree of polymerization greater than or equal to 3.

It is also possible to introduce other products or other mixtures of products such as dianhydrohexitol dialkyl ether, dianhydrohexitol monoalkyl ether or dianhydrohexitol monoalkyl ether monoalkyl carbonate which may be synthetic co-products of (A1) or (A2) ). It is also possible to introduce chain terminating agents, which are compounds comprising only one function capable of reacting with an alcohol or carbonate function. However, on all the monomers introduced into the reactor, it is preferred that the sum of (A1), (A2), (B1) and (B2) constitutes more than 90 mol% of all the monomers introduced, advantageously more than 95% or more than 99%. Most preferably, the monomers introduced into the reactor consist essentially of (A1), (A2), (B1) and (B2). Of course, it is preferred to limit the amount of diaryl carbonate and halogenated monomers introduced, for example to amounts less than 5% of the total number of moles of monomers introduced. In a particularly preferred embodiment, no monomer selected from diaryl carbonates and halogenated monomers is introduced.

Molar ratio of (AD and (A2) to (B1) and (B2)

The molar ratio in the reactor of (A1) and (A2) with respect to (B1) and (B2) corresponds to the following formula:

Advantageously, the molar ratio in the reactor of (A1) and (A2) with respect to (B1) and (B2) as defined above is strictly less than 1 and greater than 0.5, in particular strictly less than 1 and greater than 0.7, more particularly strictly less than 1 and greater than 0.9.

The very particular choice of this molarity and thus this excess in the other diol (B1) and / or triol (B2) leads to oligocarbonates polyols having a hydroxyl function at each end of the chain, which makes them useful for the preparation of polymers, such as polyurethanes.

The lower the ratio, the lower the molar mass of the oligocarbonate obtained.

According to the invention, said ratio and the nature of the diols (B1) and optionally (B2) are chosen so as to obtain a solid oligocarbonate polyol at room temperature (23 ° C).

The order of the introduction steps (1) and (2) does not matter. Step (1) can be carried out before step (2) or vice versa. These two steps can also be performed simultaneously. According to one variant, a premix of (A1) and / or (A2) and (B1) and / or (B2) is carried out before introducing them into the reactor. When dimer (A2) is used in the process, it can be introduced in admixture with (A1). This mixture can be for example made directly according to the synthesis method described in International Application No. WO 2012/136942. In the case where mixtures of monomers or dimers are introduced, the amount of each of these monomers can be determined by chromatographic methods, such as, for example, gas chromatography (GPC).

For example, to determine the amounts of (A1) and (A2) of a mixture, the amounts of each of the constituents can be measured by GPC by analysis as trimethylsilyl derivatives.

The sample can be prepared according to the following method: In a beaker, weigh 500 mg of sample and 50 mg of glucose pentaacetate (internal standard) of known purity. Add 50 ml of pyridine and stir until completely dissolved. Take 1 ml in a scoop, add 0.5 ml of bis (trimethylsilyl) -trifluoroacetamide and heat for 40 minutes at 70 ° C.

To realize the chromatogram, one can use a VARIAN 3800 chromatograph equipped with:

a DB1 column 30 m long and 0.32 mm in diameter with a film thickness of 0.25 μm,

a type 1 injector 177 equipped with a focus liner with glass wool and heated to 300 ° C. using a split ratio of 30, the helium flow rate being 1.7 ml / min,

- a FID detector heated to a temperature of 300 'Ό set with a sensitivity of 10 ^{~ 11} .

In split mode, 1, 2 of the sample can be introduced into the chromatograph, the column being heated from 100 ° C. to 320 ° C. with a ramp of 7 ° C./min and then a 15 min stage. at 320 ° C. Under these conditions of analysis, when (A1) is dimethyl carbonate of isosorbide and (A2) dimers of (A1), (A1) has a relative retention time of about 0.74, (A2) has a time relative retention ranging from about 1.34 to 1.79, the internal standard having a retention time of about 15.5 minutes.

Using the chromatogram, the mass percentage of each of the constituents can be calculated by determining the area of the corresponding peaks and calculating, for each constituent, the ratio of the area of the peak corresponding to it to the total area of all the components. peaks (with the exception of the peak of the internal standard).

Transesterification polvcondensation reaction

To allow the formation of the polycarbonate according to the process of the invention, the monomer (A1) and / or the dimer (A2) reacts with the monomer (B1) and / or (B2) by a transesterification reaction, this reaction being conducted in a reactor.

This reaction can be carried out in the absence of catalyst. However, the presence of a suitable catalyst makes it possible to accelerate the reaction and / or to increase the degree of polymerization of the polycarbonate thus formed during step (3).

The type and transesterification condensation conditions of step (3) are not particularly limited.

However, step (3) is advantageously in the presence of a known transesterification polycondensation catalyst, advantageously a catalyst comprising at least one alkali metal or alkaline earth metal ion, a quaternary ammonium ion, a quaternary phosphonium ion , a cyclic nitrogen compound, a basic boron compound or a basic phosphorus compound.

As an example of a catalyst comprising at least one alkali metal ion, mention may be made of cesium, lithium, potassium or sodium salts. These salts may in particular be carbonates, hydroxides, acetates, stearates, borohydrides, borides, phosphates, alcoholates or phenolates, as well as their derivatives.

As the catalyst comprising at least one alkaline earth metal ion, mention may be made of calcium, barium, magnesium or strontium salts. These salts may in particular be carbonates, hydroxides, acetates or stearates and their derivatives.

As regards the basic compounds based on boron, it is preferably salts of alkyl or phenyl boron derivatives such as tetraphenyl boron. Catalysts comprising basic phosphorus compounds may be phosphines. Catalysts comprising a quaternary ammonium ion are preferably hydroxides such as tetramethylammonium hydroxide.

Catalysts comprising a cyclic nitrogen compound are preferably triazole, tetrazole, pyrrole, pyrimidine, pyrazine, pyridazine, picoline, piperidine, pyridine, aminoquinoline or imidazole derivatives.

Preferably, the catalyst is chosen from catalysts comprising at least one alkali metal ion, the catalysts comprising a cyclic nitrogen compound and catalysts comprising a quaternary ammonium ion, such as cesium carbonate, triazoles, tetramethylammonium hydroxide, most preferably cesium carbonate.

The molar amount of catalyst, if any, relative to the amount of (A1) and (A2) is advantageously from 10-7% to 1%, preferably from 10-4% to 0.5%. Its amount can be adjusted depending on the catalyst used. For example, use is preferably made of 10 ³ to 10 ^'% catalyst comprising at least one alkali metal ion.

Optionally additives such as stabilizers may be added to (A1) and / or (A2) and (B1) and / or (B2).

The stabilizer may be for example a phosphoric acid-based compound such as trialkyl phosphates, based on phosphorous acid such as phosphite derivatives or phosphates, or a salt of these acids, for example zinc salts; this stabilizer makes it possible to limit the coloration of the polymer during its manufacture. Its use can be advantageous especially when carrying out the melt polycondensation. However, the amount of stabilizing agent is generally less than 0.01% of the total number of moles of (A1), (A2), (B1) and (B2). In the polycarbonate manufacturing process according to the invention, the polycondensation step of (A1) and / or (A2) and (B1) and / or (B2) is carried out in step (3). The type and conditions of polymerization are not particularly limited. This reaction can be carried out in the molten state, that is to say by heating the reaction medium in the absence of a solvent. This polymerization can also be carried out in the presence of a solvent. This reaction is preferably carried out in the molten state.

Step (3) is performed for a time sufficient to obtain a polycarbonate. Advantageously, the duration of step (3) ranges from 1 hour to 24 hours, for example from 2 to 12 hours.

At least part of step (3) of the process according to the invention can be carried out at a temperature ranging from 100 ° C. to 250 ° C., preferably from 150 ° to 235 ° C. preferentially, the reactor is thermoregulated during step (3) at a temperature ranging from 100 ° C to 250 ° C, preferably from 150 ° C to 235 ° C.

It is possible to conduct the whole of step (3) in isotherm. However, it is generally preferred to increase the temperature during this step, either in temperature increments or using a temperature ramp. This increase in temperature during step (3) makes it possible to improve the degree of progress of the polycondensation reaction by transesterification and thus to increase the molecular weight of the polycarbonate finally obtained, the latter also having a lower coloring. than when the whole of step (3) of the process is carried out at its highest temperature.

It is of course preferred to carry out step (3) under an inert atmosphere, for example under nitrogen.

In order to eliminate the alcohols generated during the process according to the invention, the vacuum in the reactor is not necessary because the alcohols generated can be distilled more easily than the phenol. The process according to the invention thus has the advantage that the transesterification polycondensation step does not necessarily take place under high vacuum. Thus, according to a variant of the process of the invention, at least part of step (3) is carried out at a pressure ranging from 30 kPa to 1 10 kPa, advantageously from 50 to 105 kPa, preferably from 90 to 105 kPa, for example at atmospheric pressure. Preferably, at least half of the total duration of step (3) is performed at this pressure.

However, step (3) can be carried out during the entire duration or during a portion under a little more vacuum, for example with a pressure inside the reactor of between 100 Pa and 20 kPa. Obviously, this vacuum is regulated according to the temperature inside the reactor and the degree of polymerization: when the degree of polymerization is low, in case of too low pressure and too high temperature, the reaction can not be done correctly because the monomers are removed from the reactor by distillation. This vacuum step a little further can be performed at the end of the reaction, which allows more than eliminate some of the residual species.

The reactor is generally equipped with a means for removing the alcohols generated during the transesterification polycondensation reaction, for example a distillation head connected to a condenser.

The reactor is generally equipped with a stirring means such as a blade stirring system.

The monomer (A1) and / or the dimer (A2) have the advantage of alternately reacting with the monomers (B1) and / or (B2) during step (3). The reaction thus leads to an oligomer having an alternating architecture. It is possible to carry out one or more additional monomer introduction steps (B1) and / or (B2) after the start of the condensation transesterification step (3).

The process may be carried out discontinuously ("batch"), continuously, or semicontinuously semi-discontinuous manner.

The oligocarbonate formed during the process is recovered in step (4). This oligocarbonate can be directly converted into granules by means of a granulator or in any other form. It is also possible to carry out a purification of the product thus obtained in a step subsequent to step (4), for example by dissolving the product in a solvent such as chloroform and then precipitating by adding a non-solvent such as methanol.

By means of the process of the invention, it is possible to obtain a mass yield, defined by the ratio of the mass of oligocarbonate recovered on the mass of the sum of the monomers or dimers used, greater than or equal to 60%, advantageously greater than 70%, preferably greater than 80%.

The present invention also relates to an oligocarbonate polyol obtainable by the method according to the invention as defined above.

Advantageously, the oligocarbonate polyol according to the invention comprises a phenol content of less than 50 ppb. The residual phenol content is measured by gas chromatography on a sample previously completely hydrolysed by acid hydrolysis. Those skilled in the art can easily perform the acid hydrolysis of the oligocarbonates and analyze the reaction crude by gas chromatography with an internal standard to measure a quantitative response.

The oligocarbonate polyol obtained by the process according to the invention has a molar mass of less than 5000 g / mol and hydroxyl chain terminations.

The molar mass of the oligocarbonate can be decreased or increased respectively by decreasing, respectively increasing, the amount of monomers (B1) and / (B2) used in step (3) compared with that of (A1) and / or (A2).

The branching ratio of the oligocarbonate can be decreased or increased respectively by decreasing, respectively increasing, the amount of monomer (B2) used in step (3) compared with that of (B1). The higher the branching ratio of the oligocarbonate, the higher the crosslinking density of the polymeric material obtained from this oligomer.

The oligocarbonate polyol obtained by the process according to the invention also has an OH number greater than 100 mg KOH / g. According to one embodiment of the invention, the oligocarbonate polyol obtained by the process according to the invention has an OH number greater than 30 mg KOH / g.

According to one embodiment of the invention, the oligocarbonate polyol obtained by the process according to the invention is solid at ambient temperature (23%).

According to one embodiment of the invention, the oligocarbonates solid polyols at room temperature have a molar mass greater than or equal to 2000 g / mol.

The molar mass of the oligocarbonate polyol according to the invention can be adjusted as a function of the amount of monomers (B1) and / (B2) used in step (3) of the process according to the invention compared to that of (A1) and / or (A2). It is thus possible to reduce, respectively increase, the molar mass of the oligocarbonate by decreasing, respectively increasing, the amount of monomers (B1) and / (B2) used in step (3) compared with that of (A1 ) and / or (A2).

The present invention relates to a crosslinkable powder coating composition comprising a mixture of oligocarbonate polyol according to the invention and a hardener.

For the purposes of the present invention, the term "crosslinkable coating composition" is intended to mean a composition capable of providing a polymeric coating after crosslinking of the composition.

The crosslinkable powder coating composition contains no solvents. It is thus of economic, environmental, hygienic and occupational safety interest (reduced risk of fire, no exposure to solvents). The hardener is a monomer whose number of functions capable of reacting with a hydroxyl function is strictly greater than two. Indeed, when this number is equal to 2, the hardener only allows chain extension. On the other hand, if this number is strictly greater than two, the formation of a three-dimensional network becomes possible, leading to an increase in the hardness of the material thus obtained. According to one embodiment, the hardener is chosen from polyisocyanates, preferably methylenediphenyl diisocyanate trimers (MDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H12MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HMDI) or lysine diisocyanate (LDI),

the isocyanate prepolymers of the dendrimer type, prepared from compounds having several alcohol or amine functions and polyisocyanates prepared so that the dendrimer formed has only reactive isocyanate functions at the end of the branch, the dendrimer containing or not containing free di or triisocyanates,

polyepoxides, such as copolymers (styrene-methyl methacrylate-glycidyl methacrylate) such as Joncryl® ADR 4300 from BASF,

polyanhydrides, such as styrene-maleic anhydride copolymers, for example the multifunctional resins SMA® from Cray Valley,

compounds having an epoxide function and a halo function, preferably epichlorohydrin,

polyacids, preferably mellitic acid or its derivatives, such as trimellitic acid or pyromellitic acid,

oxychlorides, preferably phosphorus oxychloride,

trimetaphosphates, preferably sodium trimetaphosphate,

alkoxysilanes, preferably tetraethoxysilane,

carbonyl biscaprolactam, or

tetraethyl orthosilicate.

The present invention also relates to a method of manufacturing a coating on a substrate comprising the following steps:

(1) The deposition on the substrate of a layer of the coating composition according to the invention, then

(2) Crosslinking of the layer applied in step (1).

The substrate on which the powder coating composition according to the invention can be applied may be of any kind. It may be a particular solid substrate including wood, metal, plastic, glass or paper.

The deposition of the composition may be carried out according to any means known to those skilled in the art, for example by spraying, in particular by powder coating, by dip coating in a fluidized bath, or by flame spraying. In the case of powder coating, also known as electrostatic spraying or electrostatic powdering, the projection of the composition is done by electrostatic spray, which carries a charge. The composition is in the form of a very fine cold powder which is charged by an electric field. The part to be coated, conductive, carries an opposite charge; the powder, attracted by Coulomb's force, thus temporarily adheres to the piece. Then the part is passed to the oven, which allows the melting and crosslinking of the coating composition.

The dip coating comprises heating the substrate to be treated in an oven at a temperature slightly above the melting temperature of the coating composition. Then it is sufficient to soak the hot part for a few seconds in a bath of the pulverulent composition previously fluidized. The fine powder in suspension melts immediately in contact with the hot substrate, on which it adheres, to give a uniform coating. The thickness of the coating depends on the duration of the soaking.

In the case of flame spraying, the powdery composition is projected through the flame of an oxyacetylene torch, which causes the melting of the composition. The coating composition is therefore deposited on the surface to be coated in molten form.

The thickness of the layer deposited on the substrate is adjusted according to the thickness of the coating that is desired. The thickness of the deposited layer may, for example, be between 100 nm and 2 mm, in particular from 100 to 500 micrometers. Preferably, the layer has a uniform thickness, so as to obtain a uniform final coating.

The step (2) of crosslinking of the composition may in particular be carried out under the action of heat or by irradiation with a UV beam, optionally in the presence of a catalyst.

In order to improve the properties of the network and / or to limit the energy to be supplied during the crosslinking, in particular by heating, it may be advantageous to modify the reactive functions involved in the crosslinking. Thus, it is possible, for example, to add monomers to the composition to be crosslinked, such as methyl methacrylate.

According to a particular embodiment, heating is performed at a temperature ranging from 100 ^<C to 250 ° C, preferentially 150 ^<C to 200 ^<C. In particular, the temperature may be increased by temperature steps or using a temperature ramp.

The duration of the heating may especially be between 1 h and 5 h, preferably between 1 h 30 and 3 h. Heating can also be carried out under vacuum.

The present invention also relates to a polymeric coating obtainable by the method of manufacturing a coating as described above.

The coating according to the invention in particular be an adhesive, a paint, a lacquer, a varnish or a resin.

Embodiments will now be detailed in the following examples. It is pointed out that these illustrative examples in no way limit the scope of the present invention.

Examples

Analytical methods used:

DSC: measure of Tq

The thermal properties of the polyesters were measured by differential scanning calorimetry (DSC): The sample is first heated under a nitrogen atmosphere in an open crucible of 10 to 280 ° C (10 ^< C.min ^{~ 1} ). , cooled to 10 ^<C (10 ° C.min ^-1) then warmed to 320 ^ in the same conditions as the first step. The glass transition temperatures (Tg) were taken at the midpoint of the second heater. The possible melting temperatures are determined on the endothermic peak (onset of the peak) in the first heating. In the same way the determination of the enthalpy of fusion (area under the curve) is carried out at the first heating. Size Exclusion Chromatography: Measurement of Mn

Regarding Mn, it is determined by size exclusion chromatography in THF using polystyrene standards. The sample is prepared by dissolution in THF at a concentration of 5 mg / ml.

Determination of alcohol index (OHI)

The OH number is determined by 1 H NMR using a derivatization technique by adding trifluoroacetic anhydride and α, α, α-trifluorotoluene as internal standard.

For this purpose, solubilize 10 mg of oligocarbonate diol in 0.6 ml of CDCl3 and then add excess ATFA to 24 hours of reaction. Addition of 10 μl of α, α, α-trifluorotoluene (internal standard) before analysis by 1 H NMR.

The OH level is determined by comparing the peak integrations between 5.4 and 5.6 ppm (representing the proton signals at α derivatized OH) to the sum of the integrals. peaks between 1.4 and 1.19 ppm and between 4.05 and 4.15 ppm. Those skilled in the art can easily recover the OH number once

membership

Adhesion is measured according to ASTM Standard D3359-09. Mechanical properties

The mechanical properties of the polymers were evaluated according to the following standards:

Bending test: determination of the bending stress at break (ISO 178: 2010 standard).

Tensile test: determination of elongation at break in tension (ISO 527-1: 2012). Impact resistance: determination of Charpy impact characteristics (DIN EN ISO 179-1: 2010 standard, not notched: ISO 179/1 eU or notched: ISO 179/1 eA).

Examples of Oligocarbonate Synthesis According to the Invention

Isosorbide dimethyl carbonate, which is useful for the process for producing the polycarbonate diol oligomers according to the invention, is obtained according to the protocol described below.

Synthesis of Isosorbide Dimethylcarbonate (DMCI)

It is introduced into a reactor with a capacity of 20 liters, heated by a heat transfer fluid bath, equipped with a mechanical stirring system, a system for controlling the temperature of the reaction medium and a grinding column surmounted by a reflux head, 800 g of isosorbide (5.47 mol) then 5362 g of dimethyl carbonate (= 20 equivalents of dimethyl carbonate) and 2266 g of potassium carbonate. The reaction mixture is heated for one hour at total reflux, at which time the temperature of the vapors at the top of the column reaches 64.degree ^. C., before beginning the removal of the methanol formed. The heating of the reaction medium is then maintained at a temperature of between 68 ° C. and 75 ° C. for 13 hours, at which time the temperature of the vapors at the top of the column reaches 90 ° C. and stabilizes at this temperature (point boiling of dimethyl carbonate). This is a sign that the transesterification reaction is complete and no more methanol is formed.

A part of the product obtained according to Synthesis 1 is distilled under high vacuum (<1 mbar) on a scraped-film evaporator in "short patch" configuration. The evaporator is heated to 140 ° C. and the product is introduced at 70 ° C. with a flow rate of 140 g / h. The distillate obtained is a white solid containing 100% by weight of isosorbide dimethyl carbonate and contains no trace of dimers.

Preparation of oliqocarbonates

In a 200 ml capacity reactor, heated by a ceramic furnace, equipped with a mechanical stirring system with a blade, a system for controlling the temperature of the reaction medium, and a tubing of introduction of nitrogen, a distillation head connected to a condenser and a container for collecting the condensates, and a controlled vacuum system, a quantity of isosorbide dimethyl carbonate (A1) and diols (B1): cyclohexane dimethanol, spiro glycol ^* and tricyclodecane trimethanol (TCDDM) with the amounts expressed in Table 1 below and cesium carbonate. The molar ratio (A1) / (B1) is 0.92 for 1. The amount of cesium carbonate is 17.1 mg (2.5 x 10 ^-4 mol).

The plant is placed under a nitrogen atmosphere and the reaction medium is heated by means of the heat transfer fluid. The temperature is gradually raised to 65 ° C. so that the molten reaction medium is homogeneous and five "vacuum (300 mbar) - nitrogen (flow)" cycles are applied before continuing the temperature rise. The temperature rise between each level is in 15 minutes. A first step takes place at a temperature of Ι ΟΟ 'Ό under a nitrogen flow of 5 ml / min of nitrogen for 2 hours. The temperature is subsequently brought to 180 ° C. in 15 minutes and a vacuum of 50 mbar is applied. This step lasts 3 hours.

The product is then cooled under nitrogen and poured into a pillbox when the temperature is around 60 ° C.

Examples 1 to 3 describe the syntheses and properties of the reactions where only one diol (B1) was employed, the nature of the diol (B1) having been modified.

Nature of Diol Qty Diol QtyDMCI IOH (mg Mn

Example Tg (° c) aspect

(B1) (B1) (g) (A) (g) KH / g) (g / mol)

cyclohexane

EX 1 17.92 30 64 43 2800 solid white dimethanol

EX 2 spiro glycol * 37.83 30 76 37 3270 solid white

EX 3 TCDDM 24.43 30 69 41 2870 solid white

^* 3,9-Bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] und ecane Examples of Use of Oligocarbonates According to the Invention

EXAMPLE 4 Use of Oligocarbonate Polyols According to the Invention in Powder Coating Formulations Based on Anhydrides

20 g of the oligomer of Example 1 are mixed with 1.55 g of pyromellitic anhydride. This mixture is deposited by a spray gun on a metal Q panel. This Q panel covered with the powder is then placed in an oven at 200 ° C for 8 hours to initiate the crosslinking, and then for 16 h at 245 ^< C.

The Q panel is then cooled to room temperature and an adhesion test according to ASTM Standard D3359-09 is applied. The membership rating gives a level of 5 (very good adherence).

Claims

claims

1. A crosslinkable powder coating composition comprising a hardener and an oligocarbonate polyol devoid of aromatic groups and phenolic functions, said oligocarbonate polyol being obtainable by a process comprising:

A step (1) of introduction into a reactor:

a monomer of formula (A1):

(A1) in which R 1 and R ₂ are identical or different alkyl groups, or a dimer of formula (A2):

(A2)

wherein R ₃ and R ₄ are the same or different alkyl groups, o or a mixture of (A1) and (A2);

^■ a step (2) introducing into the reactor a monomer diol (B1) or a triol monomer (B2) or a mixture of (B1) and (B2), (B1) and ( B2) being both different from (A1) and (A2); the molar ratio in the reactor of (A1) and (A2) with respect to (B1) and (B2) corresponding to the following formula:

a subsequent step (3) of polycondensation by transesterification of the monomers and dimers (A1), (A2), (B1) and (B2) to obtain a solid oligocarbonate polyol having a molar mass of less than 5000 g / mol and at least two terminations of hydroxyl type chain,

^■ a step (4) for recovering the oligocarbonate polyol.

2. crosslinkable powder coating composition according to claim 1, characterized in that the monomer (A1) is introduced into the reactor in step (1) alone or in admixture with the dimer (A2).

3. crosslinkable composition of powder coating according to claims 1 or 2, characterized in that the molar ratio in the reactor of (A1) and (A2) with respect to (B1) and (B2) having the following formula:

[ψ ₊ ψν

(Bl) (B2)

L? ^" T ^" J is strictly less than 1 and greater than 0.5, in particular strictly less than 1 and greater than 0.7, more particularly strictly less than 1 and greater than 0.9.

4. crosslinkable powder coating composition according to any one of claims 1 to 3, characterized in that R 1, R ₂ , R 3 and R ₄ are independently selected from alkyl groups comprising from 1 to 10 carbon atoms, in particular from 1 to 6 carbon atoms, more particularly 1 to 4 carbon atoms, more particularly the methyl or ethyl groups.

5. crosslinkable powder coating composition according to any one of claims 1 to 4, characterized in that the monomer (A1) is an isosorbide dialkylcarbonate, in particular an isosorbide diethylcarbonate or isosorbide dimethylcarbonate.

6. crosslinkable composition of powder coating according to any one of claims 1 to 5, characterized in that the monomer diol (B1) and the monomer triol (B2) are chosen from aliphatic diols or triols, in particular linear or branched, or cyclic diols or triols, aromatic or nonaromatic.

7. crosslinkable powder coating composition according to claim 6, characterized in that the diol (B1) is selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol or 1,10-decanediol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, 1,3-pentanediol, 1,4-hexanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol or 2-methyl-1, 3-propanediol.

8. crosslinkable powder coating composition according to claim 6, characterized in that the diol (B1) is chosen from the following cyclic diols:

■ dianhydrohexitols such as isosorbide, isomannide and isoidide;

^■ the tricyclodécanediméthanols;

^■ pentacyclopentanedimethanols;

^■ the adamantanediméthanols such as 1, 3-adamantanediméthanol;

^■ tricyclodecanediols;

^■ pentacyclopentadecanediols;

^■ decalindiols;

■ norbornanediols;

^■ or adamantanediols

^■ spiroglycol; ^■ 2,2,4,4-tetramethyl-1, 3-cyclobutanediol,

^■ Di-O-methylene-D-glucitol and dimethyl-di-O-methylene-D-glucarate,

^■ 1,4-Benzenedimethanol,

^■ 1,3 benzene dimethanol,

■ 1,5 benzene dimethanol,

^■ The 2.5 benzene furan dimethanol,

^■ Naphthalene-2,6-dicarboxylate.

9. crosslinkable composition of powder coating according to any one of claims 1 to 8, characterized in that step (3) is in the presence of a polycondensation catalyst by transesterification, preferably a catalyst comprising at least one ion of alkali metal or alkaline earth metal, a quaternary ammonium ion, a quaternary phosphonium ion, a cyclic nitrogen compound, a basic boron compound or a basic phosphorus compound.

10. crosslinkable powder coating composition according to any one of claims 1 to 9, characterized in that the molar amount of catalyst relative to the amount of the monomer (A1) and dimer (A2) is advantageously 10 ^"7 % at 1% by weight, preferably from 10 ^-4 % to 0.5% by weight.

1 1. Crosslinkable powder coating composition according to any one of Claims 1 to 10, characterized in that step (3) is carried out under an inert atmosphere, for example under nitrogen.

12. crosslinkable powder coating composition according to any one of claims 1 to 1 1, characterized in that at least a portion of step (3) is carried out at a temperature ranging from 100 ° C to 250 ° C, preferably 150 ^<C to 235 ° C.

13. Crosslinkable powder coating composition according to any one of claims 1 to 12, characterized in that the hardener is chosen from:

polyisocyanates, preferably methylenediphenyl diisocyanate trimers

(MDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H12MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HMDI) or lysine. diisocyanate (LDI),

the isocyanate prepolymers of the dendrimer type, prepared from compounds having several alcohol or amine functions and polyisocyanates prepared so as to the dendrimer formed has only reactive isocyanate functions at the end of the branch, the dendrimer containing or not free di or triisocyanates,

polyanhydrides, such as styrene-maleic anhydride copolymers, for example the multifunctional resins SMA® from the company Cray Valley,

oxychlorides, preferably phosphorus oxychloride,

trimetaphosphates, preferably sodium trimetaphosphate,

alkoxysilanes, preferably tetraethoxysilane,

carbonyl biscaprolactam, or

tetraethyl orthosilicate.

A method of manufacturing a coating on a substrate comprising the steps of:

(1) The deposition on the substrate of a layer of the crosslinkable coating composition according to any one of claims 1 to 13, and

(2) Crosslinking of the layer applied in step (1).

15. The method of claim 14, characterized in that the step (1) of deposition of the composition is carried out by spraying, in particular by powder coating, by coating by dipping in a fluidized bath or by flame spraying.

16. The method of claim 14 or 15, characterized in that the step (2) of crosslinking the composition is carried out under the action of heat or by irradiation with a UV beam, optionally in the presence of a catalyst.

17. A polymeric coating obtainable by the process according to any one of claims 14 to 16.