MULTIFUNCTIONAL ACRYLIC ETHER-ESTER PRODUCTS MODIFIED WITH CARBOXYLIC ANHYDRIDE OR ITS POLYACID FORM, PROCESS FOR PREPARING SAME AND ASSOCIATED CROSSLINKABLE COMPOSITIONS

Abstract

The invention relates to a multifunctional acrylic product having a number-average functionality f of acrylate groups greater than 2.1, which is the product of reaction by esterification and by etherification, via Michael addition reaction, between a) a polyol or a mixture of polyols R(OH).sub.m having a functionality m of at least 3 for a polyol alone or having an average functionality greater than 2.1 for a mixture of polyols, and b) the acrylic acid (R.sub.1OH) in the presence of c) at least one cyclic polycarboxylic anhydride or of its polyacid form having a carboxy functionality z of at least 2 and up to 4, the ratio r.sub.1 of number of carboxy groups of said anhydride or polyacid c) with respect to those of the acrylic acid b) r.sub.1=CO.sub.2Hc/CO.sub.2Hb being from 0.01 to 0.4 with overall r=CO.sub.2H/OH<1, said acrylic product comprising in its composition both: units A) of oligoether-ester acrylate that are derived from a) and b) and units B) of oligoester acrylate that are derived from c),
said acrylic product being a mixture of acrylic products comprising at least one acrylic product p1 chemically linking, in its molecular structure, the two types of units A) and B) as defined above.

The invention also relates to a process for preparing said product, to crosslinkable compositions comprising same and to the use thereof in coatings, sealing, moulding or composite compositions, chemical sealing compositions, 3D printing compositions or compositions for 3D objects produced layer-by-layer. One particular advantage of these compositions is their low shrinkage despite their high functionality.

Claims

1. Multifunctional acrylated product having a number-average functionality f greater than 2.1 acrylic groups per mole of said product and with a density of said acrylic groups DS ranging from 2 to 12 mmol per g of said product, said product being the product of reaction by esterification and by etherification, by Michael addition reaction, between: a) a polyol R(OH).sub.m or a mixture of polyols R(OH).sub.m, of functionality m of at least 3 for a single polyol present and a number-average OH functionality greater than 2.1 for a mixture of said polyols, and b) the acrylic acid represented by R.sub.1OH, said reaction between a) and b) taking place in the presence of c) at least one cyclic carboxylic anhydride or of its polycarboxylic acid form R.sub.2(CO.sub.2H)z, of carboxy group (—CO.sub.2H) functionality z of at least 2 and ranging up to 4: the ratio r.sub.1 of number of carboxy groups of said anhydride c) relative to those of b) acrylic acid, r.sub.1=(CO.sub.2H).sub.c/(CO.sub.2H).sub.b ranging from 0.01 to 0.4, the carboxy groups being overall in deficit relative to the hydroxyl groups of said polyol a), with r=CO.sub.2H/OH<1, said acrylic product comprising in its composition both: units A) of oligoether-ester acrylate that are derived from the reaction of a) and of b), formed by a Michael addition reaction: of the OH groups of said polyol a) or of OH groups of hydroxylated partial acrylates formed on the unsaturation of the acrylic acid b) or on the unsaturation of one of the acrylates formed by esterification with b) and simultaneous esterification with b) of said polyol a) and of said hydroxylated partial acrylates or (simultaneous esterification) with the carboxy groups of the carboxylated Michael adduct formed between a) and b), and units B) of oligoester acrylates derived from c) by a reaction of esterification with said anhydride or with its polyacid form c) of said polyol a) or of said hydroxylated partial acrylates or of the hydroxylated ether-ester acrylates formed, said acrylic product being a mixture of acrylic products comprising at least one acrylic product (p1) chemically linking, in its molecular structure, the two types of units A) and B) as defined above.

2. The product of claim 1, having an overall composition represented by the following average general formula (I):
R.sub.1O-[[A].sub.a-[B].sub.b].sub.n—R(OR.sub.1).sub.m-1  (I) with a and b representing the average mole fraction of each unit A) and B) per overall average unit of said product and with a+b=1 and a/b ranging from 0.15 to 22, n being the number of repeat overall units, with average n per mole of product n.sub.ave ranging from 0.2 to 10.

3. The product of claim 1, wherein the product comprises said product p1 and that said product p1 has a molecular structure defined according to general formula (II) below:
(R.sub.1O).sub.m-1—R—[—[O—CH.sub.2CH.sub.2—CO.sub.2—R(OR.sub.1).sub.m-2].sub.a[O.sub.2C—R2(CO.sub.2X).sub.z-2—CO2—R(OR.sub.1).sub.m-2].sub.b].sub.n—OR1  (II) and with the presence of at least four products having a different n, corresponding to n=0 and n=1, n=2 and n=3 with: R.sub.1 being the acryloyl radical, R being the residual radical of said polyol R(OH).sub.m or representing an average radical of a mixture of polyols, R.sub.2 being the residue of valency z of said anhydride or its polycarboxylic acid form and X being —R(OR.sub.1).sub.m-1 with X possibly being essentially, i.e. more than 95%, —R(OR.sub.1).sub.m-1 and the rest (less than 5%) of X being H, with an acid number not exceeding 15 mg KOH/g, n being the number of repeat units and a and b being the respective mole fractions of the particular units in the overall repeat unit with the ratio a/b ranging from 0.15 to 22.

4. The product of claim 1 wherein it comprises, in addition to said product p1, the oligoether-ester acrylate product p2 based on units A) of general formula (III) below:
(R.sub.1O)—[—R[OR.sub.1].sub.m-2—O—(C═O)—CH.sub.2—CH.sub.2—O—].sub.n—R—(OR.sub.1).sub.m-1  (III) with the presence of at least four products having a different n and corresponding to n=0 and n=1, n=2 and n=3 and n being the number of repeat units.

5. The product of claim 1 wherein is comprises, in addition to said product p1, the oligoester acrylate product p3 of the general formula (IV) below:
(R.sub.1O)—[—R[OR.sub.1].sub.m-2—O—(C═O)—R2(C═O)O—].sub.n—R—(OR.sub.1).sub.m-1  (IV) with the presence of at least four products having a different n and corresponding to n=0 and n=1, n=2 and n=3 and n being the number of repeat units.

6. The product of claim 5, wherein it comprises a product p2 as defined according to formula (III) of claim 4, said product p1 is as defined according to formula (II) of claim 3 and the three products p1, p2 and p3 thus defined each comprise at least a fifth product corresponding to n=4 and, optionally, an additional product corresponding to n=5.

7. The product of claim 1 to 6, wherein said product p1 has the following general formula (V):
(R.sub.1O)—[—R[OR.sub.1].sub.m-2—O.sub.2C—CH.sub.2—CH.sub.2—O—].sub.n—R—(OR.sub.1).sub.m-2—O.sub.2C—R.sub.2(CO2—X.sub.1).sub.z-2—CO.sub.2—X.sub.2  (V) with R.sub.2 being the radical having valency z corresponding to said carboxylic anhydride or to said polycarboxylic acid and X.sub.1 and X.sub.2 possibly being identical or different and chosen from: —R(OR.sub.1).sub.m-1 or —R(OR.sub.1).sub.m-2—[O—CH.sub.2—CH.sub.2—CO.sub.2—R(OR.sub.1).sub.m-2].sub.n—(OR.sub.1) or in part H or in part the residue of a reactive blocking agent chosen from a monofunctional reactive blocking agent, reactive with the carboxy group.

8. The product of claim 1 where the overall molecular distribution in terms of n of said product is such that it represents at least 80% by weight for n ranging from 0 to 4 and no more than 20% by weight of said distribution for n being greater than 4, with a number-average weight Mn of said product, measured by GPC in THF and expressed in polystyrene equivalents, ranging from 500 to 1000.

9. The product of claim 1 wherein said polyol a) has a functionality m for polyol a) alone of at least 3 and that said product comprises linear oligoether-ester acrylate products p2 according to general formula (III) and also at least one oligoether-ester acrylate product of branched structure.

10. Acrylated product, wherein it can be obtained by simultaneous or successive and alternating reactions between a) a polyol R(OH).sub.m or a mixture of polyols R(OH).sub.m, having a functionality m of at least 3 for a polyol a) alone, or having a number-average functionality with respect to m greater than 2.1 for a mixture of polyols R(OH).sub.m and b) the acrylic acid (R.sub.1OH) in deficit relative to a), and in the presence of c) at least one cyclic carboxylic anhydride or of its polyacid form having a carboxy group functionality z ranging from 2 to 4, with an overall ratio r=CO.sub.2H/OH of less than 1 with r.sub.1 being the ratio of the carboxy groups of c) to the carboxy groups of b) acrylic acid, r.sub.1=(carboxy).sub.c/(carboxy).sub.b.

11. The product of claim 1 wherein said polyol a) is selected from polyol monomers and/or polyol oligomers with Mn for polyol oligomers not exceeding 700.

12. The product of claim 11, wherein said polyol is a polyol monomer and selected from: diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, butanediol, neopentyl glycol, hexanediol, isosorbide, glycerol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, erythritol, xylitol, dipentaerythritol and sorbitol, including the alkoxylated derivatives of the polyols mentioned.

13. The product of claim 11, wherein said polyol is a polyol oligomer chosen from polyether polyols, polyester polyols, and hydroxylated acrylic oligomers which are optionally alkoxylated.

14. The product of claim 1 wherein, in addition to said polyol a) having a functionality of at least 3, a second polyol different from the first and having a functionality of at least 2 is present, this second polyol being an oligoester diol, optionally comprising, as component in its repeat unit, said anhydride c) or its polyacid form.

15. The product of 1 wherein said polycarboxylic anhydride c) or its polyacid form or isomer of the latter is chosen from aromatic or cycloaliphatic or aliphatic polycarboxylic anhydrides or polycarboxylic acids, with the cycloaliphatic or aliphatic structures possibly being unsaturated.

16. The product of claim 15, wherein said polycarboxylic anhydride or polyacid or said isomer of the latter is aromatic and in particular selected from: (o-) phthalic anhydride, iso- or terephthalic acid, naphthenic anhydride or acid, trimellitic anhydride or acid, pyromellitic anhydride or pyromellitic acid.

17. The product of claim 15, wherein said anhydride or its polyacid form is cycloaliphatic and selected from tetrahydrophthalic anhydride and acid, dihydrophthalic anhydride and acid, nadic (bicyclo (2,2,1) hept-5-ene-2,3-dicarboxylic) anhydride and acid or cyclohexanedicarboxylic anhydride and acid.

18. The product of claim 15, wherein said anhydride or acid is aliphatic and chosen from: maleic anhydride and acid, fumaric acid, itaconic anhydride and acid, and succinic anhydride and acid.

19. The product of claim 15, wherein said anhydride or acid is chosen from: (o-) phthalic anhydride, iso- or terephthalic acid, tetrahydrophthalic anhydride and acid, dihydrophthalic anhydride and acid, nadic anhydride and acid, maleic anhydride and acid, fumaric acid, itaconic anhydride and acid, and succinic anhydride and acid.

20. The product of claim 1 wherein said anhydride or polyacid is a mixture of at least two anhydrides or polyacids c).

21. Process for preparing the product of claim 1, comprising: i) mixing in a reactor of said polyol a), of the acrylic acid b) and of said anhydride or of said polyacid c) in proportions such that the overall mole ratio r=CO.sub.2H/OH is less than 1, with r.sub.1=(CO.sub.2H).sub.c/(CO.sub.2H).sub.b being in the range of from 0.01 to 0.4 and in the presence of an acidic esterification catalyst and of a solvent forming an azeotrope with water, to form the reaction mixture, followed by ii) refluxing said reaction mixture, with simultaneous or successive and alternating reactions of esterification, by reaction of the acrylic acid b) and/or of said anhydride or polyacid c) with a hydroxyl of said polyol a) with formation of hydroxylated acrylate esters, and reactions of etherification, via Michael addition reaction of a hydroxyl of said polyol or of formed hydroxylated acrylate, to an acrylate group and/or the acrylic acid b), and reactions of esterification of the hydroxyl groups of said polyol and of said hydroxylated acrylates by said anhydride or diacid and gradual removal of the esterification water, with iii) continuation of the reaction until complete consumption of the OH functions meaning I.sub.OH<20 mg KOH/g by Michael addition reactions and esterification reactions with said acrylic acid b) and said anhydride or diacid c), and iv) neutralization of said acidic catalyst before recovery of the final product, by removal of said solvent, without any other specific purification step required.

22. Crosslinkable composition obtained by means of a process as defined according to claim 21.

23. The composition of claim 22, wherein, in the case where the calculated Mn of said product is greater than 1000, in addition to said product, the composition comprises at least one reactive diluent, selected from acrylic monomers.

24. The composition of claim 22 wherein the composition is crosslinkable via radiation, by UV radiation in the presence of a photoinitiating system or by an electron beam (EB) in the absence of a photoinitiating system and/or via a thermal radical initiating system, in particular via a peroxide initiating system (P-cure) and/or by Michael addition (M-cure) or by a mixed system.

25. The composition of claim 22 wherein the composition is a pigmented or non-pigmented coating composition or is a moulding composition or a sealing composition or a composite composition or a chemical sealing composition of a 3D printing composition or a composition for 3D objects produced layer-by-layer.

26. (canceled)

27. (canceled)

28. Crosslinked final product chosen from crosslinked pigmented or non-pigmented coatings, or chosen from moulded parts, seals, compositions, chemical seals, 3D printing or 3D objects produced layer-by-layer, obtained by the process of claim 21.

Description

EXAMPLES

1) Starting Materials Used (See Table 1)

[0077]

TABLE-US-00001 TABLE 1 starting materials used Function Trade name Chemical Abbreviated according to (REF) name name Supplier the invention Functionality TMP (Hydro) Trimethylol TMP BASF Polyol a) 3 flakes propane TEG Triethylene TEG SABIC Polyol a) 2 glycol Phthalic Phthalic PtAn ATMOSA Carboxylic 2 anhydride anhydride anhydride c) Glacial Acrylic acid AA Arkema Acrylic acid 1 acrylic acid b) Toluene Toluene Tol TOTAL Solvent MSA E-pure Methane- MSA Arkema Catalyst sulfonic acid Extra pure Hydroquinone HQ Rhodia Inhibitor hydroquinone TIB KAT ® monobutyl MBTO TIB Catalyst 256 tin oxide Chemicals Darocur ® 2-hydroxy- PI-1 BASF Photoinitiator 1173 2- methylphenyl- propan-1-one Dipropylamine Dipropylamine DPA BASF Neutralizing agent vs catalyst Grilonit ® Trimethylol TMPTGE EMS Neutralizing V51-31 propane agent vs b) for triglycidyl reducing ether residual b) Triphenyl Triphenyl TPP Rhodia Catalyst phosphine phosphine COOH vs epoxy

2) Preparation of the Products According to the Invention

2.1) Procedure for Examples According to the Invention (Examples 1 to 2)

[0078] The ratios r and r.sub.1 mentioned below in the examples correspond: [0079] r, to the overall —CO.sub.2H/—OH equivalent ratio, [0080] r.sub.1, to the —CO.sub.2H originating from the anhydride or from the diacid c)/—COOH originating from the acrylic acid b) equivalent ratio or r.sub.1=(CO.sub.2H)c/(CO.sub.2H)b.

Example 1

Preparation of a hydroxylated polyester (diol) A-1 Used as Polyol a)

[0081] 669.1 g of triethylene glycol (4.461 mol), 329.9 g of phthalic anhydride (2.229 mol) and 1.0 g of monobutyltin oxide (0.005 mol) are introduced into a 1 litre reactor equipped with an anchor stirrer and on which is mounted a florentine tube with its condenser (device enabling continuous withdrawal of the esterification water), with a nitrogen inlet (for inerting) and with a thermometer probe.

[0082] The reaction mixture is gradually brought to two temperature stationary phases of 100 and 150° C. for five hours, then to 210-220° C. for 7 hours, until an acid number of less than 5 mg KOH/g is obtained at the time of stoppage of the esterification performed by cooling the reaction medium, after having distilled 4.0 ml of water.

[0083] A hydroxylated polyester product A-1 having the following characteristics is obtained:

Appearance: clear
Residual acidity or acid number of the product: 3.0 mg KOH/g
OH number of the product: 260 mg KOH/g
Mn calculated from the OH number and a functionality of 2, giving Mn=430 g/ml.

Preparation of a Poly Phthalo-ether-ester acrylate B-1 According to the Invention

[0084] Use is made, as polyol, of a mixture of polyols based on the hydroxylated polyol (diol) A-1 of example 1 and of TMP with r=0.926 and r.sub.1=0.191.

[0085] 264.8 g of acrylic acid (AA) (3.678 mol), 212.3 g of polyester diol A-1 of example 1 (0.494 mol), 167.1 g of trimethylolpropane (TMP) (1.247 mol), 51.9 g of phthalic anhydride (0.351 mol), 250.7 g of toluene, 10.3 g of methanesulfonic acid in aqueous solution at 70% (MSA-aq) (0.075 mol), and 3.7 g of hydroquinone (HQ) (0.003 mol) are introduced into a 1 litre reactor equipped with an anchor stirrer and on which is mounted a florentine tube with its condenser (device enabling continuous withdrawal of the esterification water under solvent reflux), with an air inlet (air sparge) and with a thermometer probe.

[0086] The reaction mixture is refluxed for ten hours, thus passing from a temperature of 105° C. (starting of boiling) to 115° C., until a low acid number <15 mg KOH/g is obtained at the time of stoppage of the esterification performed by cooling the reaction mixture, after having distilled 75 ml of water.

[0087] This organic phase is neutralized at 50° C. by adding 10.6 g of dipropylamine (0.105 mole) and with stirring for 1 h before distillation under vacuum at 80-95° C. and 200-100 millibar until complete removal of the solvent with a residual toluene <0.1%. 25.5 g of trimethylolpropane triglycidyl ether (0.084 mol) and 3.1 g of triphenyl phosphine (0.012 mol) are then added and the temperature is then gradually raised to 13° C. and maintained until a residual acid number <10 mg KOH/g is obtained.

[0088] A polyphthalo(ether-ester) acrylate product B-1 having the following characteristics is obtained:

Appearance: clear

Turbidity: 9%

Viscosity at 25° C.: 8 Pa.Math.s

[0089] Residual acidity or acid number of the product: 7 mg KOH/g
OH number of the product: <20 mg KOH/g.

[0090] The molecular characteristics of B-1 are given in table 2 below.

[0091] A formulation F-1 having the following percentage composition is prepared by simple cold mixing:

B-1: 96%

PI-1: 4%

Characteristics of Formulation F-1

[0092] Reactivity: 30 m/min
Persoz hardness: 180 s

Flexibility: 20 mm

[0093] Resistance to acetone: >300 s

Example 2

Preparation of a polyphthalo-ether-ester acrylate B-2 According to the Invention

[0094] TMP is used as polyol a), with r=0.836 and r.sub.1=0.235.

[0095] 324.8 g of acrylic acid (AA) (4.511 mol), 297.6 g of trimethylolpropane (TMP) (2.221 mol), 78.4 g of phthalic anhydride (0.529 mol), 244.3 g of toluene, 13.7 g of methanesulfonic acid in aqueous solution at 70% (AMS-aq) (0.100 mol), and 1.5 g of hydroquinone (HQ) (0.001 mol) are introduced into a 1 litre reactor equipped with an anchor stirrer and on which is mounted a florentine tube with its condenser (device enabling continuous withdrawal of the esterification water under solvent reflux), with an air inlet (air sparge) and with a thermometer probe.

[0096] The reaction mixture is refluxed for 18 hours, thus passing from a temperature of 105° C. (start of boiling) to 115° C., until a low acid number <15 mg KOH/g is obtained at the time of stoppage of the esterification performed by cooling the reaction medium, after having distilled 95 ml of water.

[0097] This organic phase is neutralized at 50° C. with 14.2 g of dipropylamine (0.140 mol) and with stirring for 1 h before distillation under vacuum at 80-95° C. and 200-100 millibars until complete removal of the solvent (with residual toluene <0.1%). 22.3 g of trimethylolpropane triglycidyl ether (0.074 mol) and 3.3 g of triphenyl phosphine (0.013 mol) are then added and then the temperature is gradually raised to 125° C. and maintained until a residual acid number <10 mg KOH/g is obtained.

[0098] A polyphthalo(ether-ester) acrylate product B-2 having the following characteristics is obtained:

Appearance: clear

Turbidity: 10%

Viscosity at 50° C.: 20 Pa.Math.s

[0099] Residual acidity or acid number of the product: 8 mg KOH/g
OH number of the product: <20 mg KOH/g.

[0100] The molecular characteristics of B-2 are given in table 2 below.

[0101] A formulation F-2 having the following percentage composition is prepared by simple cold mixing:

B-2: 96%

PI-1: 4%

Characteristics of Formulation F-2

[0102]

TABLE-US-00002 TABLE 2 Molecular characteristics of the products B-1 and B-2 according to the invention m or average r.sub.1 = n.sub.ave*a n.sub.ave*b Mn average DA polyol m r = (CO.sub.2H).sub.c/ average average Calc Mn GPC f/mol mmol  a) polyol a) CO.sub.2H/OH (CO.sub.2H).sub.b (calc) (calc) A n.sub.ave (g/mol) (Dalton) (calc) (calc  TMP 2.72 0.926 0.191 0.335 0.337 0.50 0.672 599 1200 3.20 5.34  A-1 TMP 3.00 0.836 0.235 1.831 0.885 0.67 2.716 1021 1900 5.72 5.60 Reactivity: 40 m/min Persoz hardness: 290 s Flexibility: 25 mm Resistance to acetone: >300 s indicates data missing or illegible when filed

MEASUREMENT AND CHARACTERIZATION METHODS

Determination of the Appearance:

[0103] The product is observed visually in daylight, through a 60 ml colourless glass bottle, to determine whether the product is: [0104] Clear: low turbidity, it is comparable to water, [0105] Hazy: not allowing a clear view through the bottle, [0106] Cloudy: opaque bottle, no image can be seen through the bottle.

Determination of the Turbidity:

[0107] This is the percentage of scattered light relative to the total light transmitted by the sample contained in a 50 ml transparent tank (60 mm×40 mm×20 mm). The measurement is taken using a Hunterlab “Colorquest XE”® spectrocolorimeter.

Determination of the Noury Viscosity:

[0108] The time of travel, in the liquid to be characterized, of a steel ball under its own gravity is measured. Standard AFNOR XP.T51-213 specifies in particular the geometry of the container, the diameter of the ball (2 mm) and the path of the ball (104 mm). Under these conditions, the dynamic viscosity is proportional to the time of travel of the ball with one second corresponding to 0.1 Pa.Math.s.

Determination of the Acid Number (AN):

[0109] The acidity of the product to be characterized is expressed in milligrams of potassium equivalent per gram of product. For this, an acid-based titration is carried out under the following conditions: a weight w of product (approximately exactly 10 g) is dissolved in 50 ml of a toluene/ethanol mixture (2 vol/1 vol). After total dissolution, titration is performed with a potassium hydroxide solution of normality N (approximately exactly 0.1 N). The equivalent point is detected by a combined electrode controlling an automatic burette (Metrohm “716 DMS Titrino”® automatic titration machine) delivering the equivalent volume V.sub.E. After performing a blank test (50 ml of the toluene/ethanol mixture alone), which makes it possible to determine the equivalent volume V.sub.B, the acid number (AN) is calculated via the following formula:

IA=(V.sub.E−V.sub.B)*N*56.1/w

with V.sub.E and V.sub.B in ml, N in mol/l and w in grams.

Determination of the Hydroxyl Number (IOH Number):

[0110] The hydroxyl number of the product to be characterized is expressed in milligrams of potassium hydroxide equivalent per gram of product. For this, an acid-base back titration after acetylation is performed under the following conditions: a weight w of product (approximately exactly 10 grams) is dissolved in exactly 10 ml of an acetylating mixture (para-toluenesulfonic acid monohydrate: 10 g; acetic anhydride: 60 g; ethyl acetate: 500 g). The resulting mixture is reacted in a closed Erlenmeyer flask for 30 minutes with stirring at 50° C. It is cooled to ambient temperature and then the excess acetic anhydride is hydrolyzed by adding 2 ml of water which is allowed to react for 2 minutes at ambient temperature, and then by adding 10 ml of hydrolyzing solution [pyridine/water] (3 vol/2 vol) which is allowed to react for 5 minutes at ambient temperature. 60 ml of [butanol/toluene] solvent (2 vol/1 vol) are then added. After homogenization, titration is carried out with a potassium hydroxide solution of normality N (approximately exactly 0.5 N). The equivalent point is detected by a combined electrode controlling an automatic burette (Metrohm “716 DMS Titrino”® automatic titration machine) delivering the equivalent volume V.sub.E. After performing a blank test (10 ml of the acetylating mixture+2 ml of water+10 ml of hydrolyzing solution+60 ml of solvent) which makes it possible to determine the equivalent volume V.sub.B, the hydroxyl number (OH number) is calculated via the following formulae:

OH number*=(V.sub.B−V.sub.E)*N*56.1/w

with V.sub.E and V.sub.B in mol, N in mol/l and w in grams.
OH number*: apparent hydroxyl number

OH number=OH number*+AN

Determination of the Reactivity:

[0111] The formulation is applied as a 12 μm film on a contrast card (Leneta “Penoparc charts form 1B”®), and is then crosslinked using a 120 W/cm Hg Fusion lamp. The minimum passage rate (in m/min) necessary to obtain a touch-dry film is measured.

[0112] For the following hardness, flexibility and acetone resistance tests, the photo-crosslinked films are left in an air-conditioned room (T=23° C.) for 24 hours after crosslinking and before the measurements.

Determination of the Persoz Hardness According to Standard ISO 1522:

[0113] The formulation to be examined is applied as a 100 μm film on a glass plate and crosslinked with a 120 W/cm Hg Fusion lamp at a rate of 8 m/min.

[0114] The number of oscillations before damping of the oscillations (passing from 12° to 4° of amplitude) of a pendulum in contact with the coated glass plate is measured according to standard ISO 1522.

Determination of the Flexibility:

[0115] The formulation is applied as a 100 μm film on a 25/10 mm thick smooth steel plate (D-46® Q-Panel), and then crosslinked with a 120 W/cm Hg Fusion lamp at a rate of 8 m/min.

[0116] The coated plate is curved on cylindrical mandrels according to standard ISO 1519. The result is expressed as the value (in mm) of the smallest radius of curvature that can be imposed on the coating without it cracking or becoming detached from the support.

Determination of the Acetone Resistance:

[0117] The formulation is applied as a 12 μm film on a glass plate, and then crosslinked with a 120 W/cm Hg Fusion lamp at a rate of 8 m/min. The coating is rubbed with a cloth soaked with acetone. The result is the time (expressed in seconds) beyond which the film becomes detached and/or disintegrates.

Number-Average Molecular Weight Mn:

[0118] Mn calc: theoretical Mn calculated from n.sub.AVE*a and n.sub.AVE*b according to the method specified in the description, in particular for z=2:

Mn calc=M[R(OR.sub.1).sub.m]+a*n.sub.AVE*M[A]+b*n.sub.AVE*M[B] (in g/mol)

With:

[0119] Constant term: M[R(OR.sub.1).sub.m]=M[R(OH).sub.m]+54*m [0120] Motif A: M[A]=M[R(OH).sub.m]+54*(m−1) [0121] Motif B: M[B]=M[R(OH).sub.m]+M(R2)+54*(m−1)
Mn measured: measured by GPC in THF as solvent and Mn expressed in polystyrene equivalents on columns calibrated with polystyrene standards.
Number-Average Functionality of the Product with Respect to Acrylates (See Description):
Acrylate density DA: from f as defined above by dividing by calculated Mn (see definition in the description).

DA=1000*f/Mn.