MODIFIER FOR CURABLE COMPOSITIONS COMPRISING BENZYL ALCOHOL ALKOXYLATES

Abstract

The present invention relates to a modifier comprising benzyl alcohol-based alkoxylates for curable compositions comprising at least one epoxy resin and a hardener, which are obtained by reacting benzyl alcohol with alkylene oxides, the benzyl alcohol-based alkoxylates having at least one ethoxy fragment.

Claims

1. A modifier comprising benzyl alcohol-based alkoxylates for curable compositions comprising one epoxy resin and one hardener, wherein the benzyl alcohol-based alkoxylate is obtained by reacting benzyl alcohol with alkylene oxides, wherein the benzyl alcohol-based alkoxylate having at least one ethoxy fragment.

2. The modifier according to claim 1, wherein the benzyl alcohol-based alkoxylate comprises benzyl alcohol-based ethoxylates or benzyl alcohol-based mixed alkoxylates of the formula (I) ##STR00002## where a=alkoxy fragment (a)=1 to 10, b=alkoxy fragment (b)=0 to 10, c=alkoxy fragment (c)=0 to 10, R1, R2=independently hydrogen, an alkyl group having 2 to 20 carbon atoms, an aryl or alkaryl group, with the proviso that R1 is not H when R2 is methyl, and that the two R1 and R2 radicals must not both be H at the same time, R3=independently a hydrogen radical, an acetyl, phosphoric ester or alkyl group which has 1 to 20 carbon atoms and may also have further substitution.

3. The modifier according to claim 2, wherein the alkylene oxides are selected from the group consisting of-ethylene oxide (EO), propylene oxide (PO), 1,2-epoxy-2-methylpropane (isobutylene oxide), epichlorohydrin, 2,3-epoxy-1-propanol, 1,2-epoxybutane (butylene oxide, BO), 2,3-epoxybutane, 2,3-dimethyl-2,3-epoxybutane, 1,2-epoxypentane, 1,2-epoxy-3-methylpentane, 1,2-epoxyhexane, 1,2-epoxycyclohexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxynonane, 1,2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane, styrene oxide (SO), 1,2-epoxycyclopentane, 1,2-epoxycyclohexane, vinylcyclohexene oxide, (2,3-epoxypropyl)benzene, vinyloxirane, 3-phenoxy-1,2-epoxypropane, 2,3-epoxy methyl ether, 2,3-epoxy ethyl ether, 2,3-epoxy isopropyl ether, 3,4-epoxybutyl stearate, 4,5-epoxypentyl acetate, 2,3-epoxypropane methacrylate, 2,3-epoxypropane acrylate, glycidyl butyrate, methyl glycidate, ethyl 2,3-epoxybutanoate, 4-(trimethylsilyl)butane 1,2-epoxide, 4-(triethylsilyl)butane 1,2-epoxide, 3-(perfluoromethyl)-1,2-epoxypropane, 3-(perfluoroethyl)-1,2-epoxypropane, 3-(perfluorobutyl)-1,2-epoxypropane, 3-(perfluorohexyl)-1,2-epoxypropane, 4-(2,3-epoxypropyl)morpholine, 1-(oxiran-2-ylmethyl)pyrrolidin-2-one.

4. The modifier according to claim 3, wherein the alkylene oxides are used individually or in any desired mixtures for alkoxylation of the benzyl alcohol.

5. The modifier according to claim 4, wherein the benzyl alcohol-based mixed alkoxylate is prepared by reacting ethylene oxide (EO) and propylene oxide (PO) in a molar ratio of 1:10 to 10:0.

6. The modifier according to claim 5, wherein the alkoxy fragments (a) and (b) may be added onto the benzyl alcohol in statistical or random distribution.

7. The modifier according to claim 2, wherein the degree of alkoxylation is 3 to 10.

8. The modifier according to claim 2, wherein the benzyl alcohol-based alkoxylate has a terminal hydroxyl group.

9. The modifier according to claim 1, wherein the terminal hydroxyl group of the benzyl alcohol-based alkoxylate is acetylated, methylated or phosphorylated.

10. The modifier according to claim 2, wherein the polydispersity (Mw/Mn) of the benzyl alcohol-based mixed alkoxylates of formula (I) is <2.5, determined by means of GPC.

11. A method of making a benzyl alcohol-based alkoxylates comprising the steps of mixing at least one epoxy fragment as modifiers for curable compositions comprising at least one epoxy resin, and at least one hardener, and further auxiliary components.

12. The method according to claim 11 of formula (I) ##STR00003## where a=alkoxy fragment (a)=1 to 10, b=alkoxy fragment (b)=0 to 10, c=alkoxy fragment (c)=0 to 10, R1, R2=independently hydrogen, an alkyl group having 2 to 20 carbon atoms, an aryl or alkaryl group, with the proviso that R1 is not H when R2 is methyl, and that the two R1 and R2 radicals must not both be H at the same time, R3=independently a hydrogen radical, an acetyl, phosphoric ester or alkyl group which has 1 to 20 carbon atoms and may also have further substitution.

13. A curable composition comprising (1) at least one epoxy resin, (2) at least one hardener, (3) at least one modifier according to claim 1, and (4) further auxiliary components.

14. The curable composition according to claim 13, wherein bisphenol A diglycidyl ether-based epoxy resins or bisphenol F diglycidyl ether-based epoxy resins are used.

15. The curable composition according to claim 14, wherein the at least one hardener (2) is an aminic hardener selected from the group consisting of aliphatic, cycloaliphatic, araliphatic or aromatic amines or polyamines.

16. The curable composition according to claim 15, wherein the at least one hardener (2) is an acidic hardener selected from the group consisting of acids and acid anhydrides.

17. A method of making floor coatings, paints, polymer concrete, repair systems, anchoring compounds, adhesives, potting compounds and impregnations, fiber composite materials comprising the step of mixing the curable composition of claim 13 with other ingredients to prepare floor coatings, paints, polymer concrete, repair systems, anchoring compounds, adhesives, potting compounds and impregnations, fiber composite materials.

18. The method of claim 11, wherein the at least one hardener is an aminic hardener selected from the group consisting of aliphatic, cycloaliphatic, araliphatic or aromatic amines or polyamines.

19. The method of claim 11, wherein the at least one hardener is an is an acidic hardener selected from the group consisting of acids and acid anhydrides.

20. The modifier according to claim 1, wherein the benzyl alcohol-based alkoxylate comprises benzyl alcohol-based ethoxylates or benzyl alcohol-based mixed alkoxylates of the formula (I) ##STR00004## where a=alkoxy fragment (a)=2 to 7, b=alkoxy fragment (b)=1 to 7, c=alkoxy fragment (c)=0 to 6, R1, R2=independently hydrogen, ethyl, octyl, decyl or phenyl group, with the proviso that R1 is not H when R2 is methyl, and that the two R1 and R2 radicals must not both be H at the same time, R3=independently a hydrogen radical.

Description

EXAMPLE 1

Synthesis of Benzyl Alcohol-Based Propoxylates and Modifiers According to the Invention

Examples M1-M14, CM1 and CM2

[0082] A 5 liter autoclave is initially charged with the appropriate amount of benzyl alcohol together with 5 mol % of potassium methoxide under nitrogen. The reactor was inertized by injecting nitrogen to 3 bar and then decompressing to standard pressure. This operation was repeated twice more. While stirring, the contents of the reactor were heated to 100° C. and evacuated to about 100 mbar to remove the methanol from the catalysis step. Then the temperature was increased to 120° C. and the alkylene oxide(s) was/were metered in so as to give the distribution of the alkoxy fragments specified in Table 1.

[0083] The dosage rate of the alkylene oxide(s) was chosen such that the pressure in the reactor did not rise above 2 bar. After the dosage had ended, there was at first a wait period until the pressure ceased to fall, which was regarded as a sign of virtually quantitative conversion of the alkylene oxide(s). To complete the alkylene oxide conversion, further reaction was conducted for one hour. When the aim is a blockwise alkoxy structure, the above-described procedure is repeated for every pure alkylene oxide to be added on. When the aim is statistical addition of the alkylene oxides, a homogeneous mixture of the respective alkylene oxides is metered in. Finally (after addition of the last alkylene oxide or alkylene oxide mixture with appropriate further reaction), the reaction mixture was deodorized by applying a pressure (p<20 mbar), in order to remove traces of unconverted alkylene oxide. Subsequently, the benzyl alcohol-based alkoxylate was neutralized with dilute phosphoric acid and stabilized with 500 ppm of ANOX 20 AM. Subsequently, the water was removed by distillation under reduced pressure and the precipitated salts were filtered off.

[0084] In all cases, colorless to yellowish benzyl alcohol-based alkoxylates were obtained, the essential indices of which are summarized in Table 1. The structure described in the tables which follow is explained as follows: If the alkoxy fragments (for example EO or PO) are separated by a “+”, the structure is a blockwise structure; if the alkoxy fragments are separated by a “/”, the structure is a statistical structure. For simplification of the representation in the tables, the alkoxy fragments were referred to by the alkylene oxides used, EO, PO, BO and SO.

Example 1a

[0085] Acetylation of the modifier M1 according to the invention Under protective gas, a 4 liter three-neck flask equipped with dropping funnel and reflux condenser was initially charged with 1979 g of the modifier 1 together with catalytic amounts of concentrated hydrochloric acid, and heated. Then acetic anhydride was added gradually. On completion of addition, the mixture was stirred at 100° C. for another 4 h. Then acid residues present were distilled off, and a terminally acetylated modifier M1Ac with an acid number of 0.1 and a hydroxyl number of 0 mg KOH/g was obtained.

[0086] In an analogous manner, the modifier M5 was also acetylated. This gave a terminally acetylated modifier M5Ac with an acid number of 0.1 and a hydroxyl number of 0 mg KOH/g.

Example 1b

[0087] Methylation of the modifier M1 according to the invention Under protective gas, a 4 liter three-neck flask equipped with a distillation system was initially charged with 1620 g of the modifier M1 according to the invention and heated to 50° C. At this temperature, 130 mol % of sodium methoxide are added gradually. The methanol formed is distilled off. Subsequently, a water-jet vacuum is applied, the temperature is increased to 120° C. and methyl chloride is introduced into the solution with the aid of a gas inlet tube for 1.5 h. After another vacuum distillation step, methyl chloride is again introduced over a period of 1 h. Then the mixture is distilled, neutralized and filtered, and a terminally methylated modifier M1Me with an acid number of 0.1 and a hydroxyl number of 1.0 mg KOH/g is obtained.

[0088] In an analogous manner, the modifier M5 was also methylated. This gave a terminally methylated modifier M5Me having an acid number of 0.1 and a hydroxyl number of 2.4 mg KOH/g.

TABLE-US-00001 TABLE 1 Structure and physical data of the benzyl alcohol-based alkoxylates Prim. Benzyl alcohol- AN OHN OH based [mg termini alkoxylates Structure KOH/g] [%] M1 Benzyl alcohol + 3 EO 0.1 220 100 M2 Benzyl alcohol + 6 EO 0.1 147 100 M3 Benzyl alcohol + 3 EO/3 PO 0.2 128 14 M4 Benzyl alcohol + 3 PO + 3 EO 0.3 136 74 M5 Benzyl alcohol + 2 EO/2 PO 0.3 180 19 M6 Benzyl alcohol + 1 EO/5 PO 0.1 132 0 M7 Benzyl alcohol + 2 EO/4 PO 0.1 133 0 M8 Benzyl alcohol + 1 EO/3 PO 0.1 173 2 M9 Benzyl alcohol + 1 PO + 3 EO 0.1 186 71 M10 Benzyl alcohol + 3 EO + 1 PO 0.1 183 32 M11 Benzyl alcohol + 1 EO/3 PO/2 0.2 118 0 BO M12 Benzyl alcohol + 1 EO/3 PO/2 0.3 105 0 SO M13 Benzyl alcohol + 2 EO/1 PO 0.2 267 31 M14 Benzyl alcohol + 1 EO/2 PO 0.3 270 5 M1Ac Benzyl alcohol + 3 EO, 0.1 0 0 acetylated M5Ac Benzyl alcohol + 2 EO/2 PO, 0.1 0 0 acetylated M1Me Benzyl alcohol + 3 EO, 0.1 1 100 methylated M5Me Benzyl alcohol + 2 EO/2 PO, 0.1 2.4 0 methylated CM1 Benzyl alcohol + 3 PO 0.2 194 0 (comparative example) CM2 Benzyl alcohol + 6 PO 0.1 117 0 (comparative example)

[0089] M1 to M14 are modifiers according to the invention. CM1 and CM2 are comparative examples.

EXAMPLE 2

Outgassing Characteristics

[0090] The outgassing characteristics of the inventive modifier M1-12 or of the benzyl alcohol or of the comparative examples is inferred on the basis of the volatile content (VOCs and SVOCs=volatile and moderately volatile organic compounds) in accordance with the definition of DIN EN 11890-2. The volatile fractions are determined by gas chromatography according to DIN EN ISO 11890-2. Before the measurement, the alcoholic end groups were converted to the corresponding trimethylsilyl ethers by derivatization with N-methyl-N-trifluoroacetamide (MSTFA). The analysis was effected by means of gas chromatography equipped with on-column injection and FID detection. The constituents were separated on an apolar separation column (DB-5 HT; length 30 m; diameter 0.25 mm; film thickness 0.1 μm, temperature program 65° C. to 365° C. at 10° C. per minute, followed by hold time of 15 minutes at 365° C.). For quantification, the sum total of the peak areas of the constituents classified as VOC/SVOC was determined in comparison to the total peak area of all substances detected in the sample (area % evaluation). The lower the percentage, the lower the level of volatile substances that are released into the indoor environment.

TABLE-US-00002 TABLE 2 Volatile organic content of modifiers according to the invention compared to benzyl alcohol Volatile content up to a boiling point of 365° C. Structure % Benzyl Benzyl alcohol 100 alcohol M1 Benzyl alcohol + 3 EO 58.6 M2 Benzyl alcohol + 6 EO 11.7 M3 Benzyl alcohol + 3 EO/3 PO 18.8 M5 Benzyl alcohol + 2 EO/2 PO 67.2 M6 Benzyl alcohol + 1 EO/5 PO 17.2 M7 Benzyl alcohol + 2 EO/4 PO 15.4 M8 Benzyl alcohol + 1 EO/3 PO 65.9 M9 Benzyl alcohol + 1 PO + 3 EO 60.0 M10 Benzyl alcohol + 3 EO + 1 PO 63.7 M11 Benzyl alcohol + 1 EO/3 PO/2 18.4 BO M12 Benzyl alcohol + 1 EO/3 PO/2 13.1 SO M13 Benzyl alcohol + 2 EO/1 PO 61.2 M14 Benzyl alcohol + 1 EO/2 PO 61.0 M1Ac Benzyl alcohol + 3 EO, 52.3 acetylated M5Ac Benzyl alcohol + 2 EO/2 PO, 61.6 acetylated M1Me Benzyl alcohol + 3 EO, 54.7 methylated M5Me Benzyl alcohol + 2 EO/2 PO, 63.5 methylated CM1 Benzyl alcohol + 3 PO 65.4 CM2 Benzyl alcohol + 6 PO 12.2

[0091] All modifiers according to the invention are superior to benzyl alcohol in terms of outgassing characteristics. It is additionally found that the inventive M1 compared to CM1 (equal chain length) and the inventive M2 compared to CM2 (equal chain length) release a lower level of volatile organic compounds.

EXAMPLE 3

Measurement of Viscosity of the Modifier According to the Invention in Epoxy Resin Binders

[0092] The modifier according to the invention is used in epoxy resin binders without catalyst and in epoxy resin binders with catalyst, in order to examine the effect thereof on viscosity.

TABLE-US-00003 Formulation I Proportion Epikote 828, binder from Hexion 20 g M1, M1Ac, M1Me, M2-M5, M5Ac,  2 g M5Me, M6-M10, M13, M14, CM1-2, benzyl alcohol

TABLE-US-00004 Formulation II Proportion Epikote 828, binder from Hexion .sup. 20 g M1-M3, M5-M8, M13, M14, CM1-2,   2 g benzyl alcohol Salicylic acid (catalyst) 0.55 g

[0093] The binder was initially charged in PE cups, the inventive modifier or benzyl alcohol or comparative examples (CM) and optionally catalyst was metered in, and the formulations were each incorporated in a Hauschild Speedmixer at 1000 rpm for 1 min. The viscosities of the formulations were measured with an Anton Paar MCR 102 rheometer. Measurement parameters: cone/plate CP 25/2, 23° C., multiple measurement points in the range of 1-1000 1/s.

TABLE-US-00005 TABLE 3.1 Influence of the inventive modifier on the viscosity of formulation I Formula- Viscos- Viscos- Viscos- tion I ity at ity at ity at com- 10 1/s 100 1/s 1000 1/s prising Structure mPas mPas mPas Benzyl Benzyl alcohol 1710 1720 1670 alcohol M1 Benzyl alcohol + 3 EO 3970 3990 3690 M1Ac Benzyl alcohol + 3 EO, 3940 3980 3690 acetylated M1Me Benzyl alcohol + 3 EO, 3210 3000 2890 methylated M2 Benzyl alcohol + 6 EO 4970 5040 4570 M3 Benzyl alcohol + 3 EO/3 PO 5650 5710 5100 M4 Benzyl alcohol + 3 PO + 3 5877 5821 5067 EO M5 Benzyl alcohol + 2 EO/2 PO 4470 4510 4130 M5Ac Benzyl alcohol + 2 EO/2 4330 4270 3950 PO, acetylated M5Me Benzyl alcohol +2 EO/2 3910 3580 3240 PO, methylated M6 Benzyl alcohol + 1 EO/5 PO 5620 5630 5010 M7 Benzyl alcohol + 2 EO/4 PO 4870 4890 4440 M8 Benzyl alcohol + 1 EO/3 PO 3610 3660 3430 M9 Benzyl alcohol + 1 PO + 3 6104 5932 5186 EO M10 Benzyl alcohol + 3 EO + 1 5726 5662 5034 PO M13 Benzyl alcohol + 2 EO/1 PO 3226 3270 3142 M14 Benzyl alcohol + 1 EO/2 PO 3163 3191 3073 CM1 Benzyl alcohol + 3 PO 4370 4410 4040 CM2 Benzyl alcohol + 6 PO 6280 6300 5520

TABLE-US-00006 TABLE 3.2 Influence of the inventive modifier on the viscosity of formulation II Formula- Viscos- Viscos- Viscos- tion II ity at ity at ity at com- 10 1/s 100 1/s 1000 1/s prising Structure mPas mPas mPas Benzyl Benzyl alcohol 2650 2640 2510 alcohol M1 Benzyl alcohol + 3 EO 5310 5310 4750 M2 Benzyl alcohol + 6 EO 6670 6710 5820 M3 Benzyl alcohol + 3 EO/3 7080 7110 6100 PO M5 Benzyl alcohol + 2 EO/2 6140 6180 5440 PO M6 Benzyl alcohol + 1 EO/5 7680 7670 6480 PO M7 Benzyl alcohol + 2 EO/4 6850 6880 5950 PO M8 Benzyl alcohol + 1 EO/3 6870 6900 6000 PO M13 Benzyl alcohol + 2 EO/1 5180 5150 4520 PO M14 Benzyl alcohol + 1 EO/2 5320 5360 4680 PO CM1 Benzyl alcohol + 3 PO 6260 6320 5530 CM2 Benzyl alcohol + 6 PO 7960 7950 6650

Summary of Tables 3.1 and 3.2:

[0094] If the inventive modifier M1 and CM1, having the same chain length, are compared with one another, and analogously the inventive M2, M3, M6 and M7 with CM2 (equal chain length), the modifiers having ethoxy fragments are always superior to the comparative examples with pure PO in terms of the viscosity-lowering effect.

[0095] In addition, the viscosity-lowering effect can be enhanced by an end modification. It is apparent from Table 3.1 that the viscosity-lowering effect of the formulation I comprising M1Me or M5Me according to the invention is somewhat better than that of the formulation I comprising the unmodified M1 or M5 according to the invention.

EXAMPLE 4

Reaction Rate of Epoxide Hardening

Assessment of Reactivity of Curable Compositions According to the Invention on the Basis of Doubling of the Viscosity

[0096] The doubling of the initial viscosity is a measure of the reaction rate of the epoxy hardening reaction.

Composition I

[0097]

TABLE-US-00007 Proportion Epikote 828, binder from Hexion .sup. 20 g M1, M2, M3, CM1-2, benzyl alcohol   2 g Vestamin IPD, hardener from Evonik 4.54 g Resource Efficiency GmbH

[0098] The binder was initially charged in PE cups, the inventive modifier or benzyl alcohol or comparative examples was metered in, and the mixtures were each incorporated in a Hauschild Speedmixer at 1000 rpm for 1 min. The hardener was weighed in and the curable compositions were stirred in the Speedmixer at 2000 rpm for 1 min. The viscosities of the curable compositions were measured with an Anton Paar MCR 102 rheometer. Measurement parameters: cone/plate 25/2, 23° C., constant shear rate of 100 1/s, measurement lasts until doubling of the start value.

TABLE-US-00008 TABLE 4 Influence of the inventive modifier in a curable composition I on reactivity on the basis of doubling of the viscosity Compo- Starting Final Prim. sition I vis- vis- OH com- cosity cosity Time termini prising Structure mPas mPas s % Benzyl Benzyl alcohol 1490 2980 1790 100 alcohol M1 Benzyl alcohol + 3 EO 1720 3440 3100 100 M2 Benzyl alcohol + 6 EO 1710 3420 3350 100 M3 Benzyl alcohol + 3 EO/3 1760 3520 3580 14 PO CM1 Benzyl alcohol + 3 PO 1720 3440 3900 0 CM2 Benzyl alcohol + 6 PO 1870 3520 3680 0

[0099] If the inventive modifier M1 and CM1 are compared with one another, both having the same chain length, and the inventive M2 and M3 are compared with CM2, curable compositions react more quickly with the inventive modifiers having ethoxy fragments than with those having pure propoxy fragments.

EXAMPLE 5

Curing

Influence of the Inventive Modifier in a Curable Composition on Hardening

[0100] For the testing of Shore D hardness, the formulation of curable composition I was used.

[0101] The binder was initially charged in PE cups, the inventive modifier was metered in, and the mixtures were each incorporated in a Hauschild Speedmixer at 1000 rpm for 1 min. The hardener was weighed in and the curable compositions were stirred in the Speedmixer at 2000 rpm for 1 min. This was used to cast a slab of layer thickness about 5 mm. The Shore D hardnesses were measured after various intervals.

TABLE-US-00009 TABLE 5 Evolution of Shore D hardness of curable compositions according to the invention Shore D Shore D hardness hardness after 2 after 7 Composition days days I comprising Structure Shore Shore Benzyl Benzyl alcohol 86.3 88.6 alcohol M1 Benzyl alcohol + 3 EO 86.2 88.7 M1Ac Benzyl alcohol + 3 EO, 83.9 88.9 acetylated M1Me Benzyl alcohol + 3 EO, 83.8 87.5 methylated M2 Benzyl alcohol + 6 EO 84.4 88.4 M3 Benzyl alcohol + 3 EO/3 PO 84.5 85.9 M5 Benzyl alcohol + 2 EO/2 PO 85.1 88.1 M5Ac Benzyl alcohol + 2 EO/2 PO, 83.2 88.0 acetylated M5Me Benzyl alcohol + 2 EO/2 PO, 83.6 87.9 methylated M6 Benzyl alcohol + 1 EO/5 PO 85.2 87.6 M7 Benzyl alcohol + 2 EO/4 PO 85.0 87.5 M8 Benzyl alcohol + 1 EO/3 PO 82.3 87.1 M9 Benzyl alcohol + 1 PO + 3 EO 83.7 87.0 M10 Benzyl alcohol + 3 EO + 1 PO 85.9 87.0 M11 Benzyl alcohol + 1 EO/3 PO/2 83.3 86.8 BO M12 Benzyl alcohol + 1 EO/3 PO/2 82.6 85.9 SO M13 Benzyl alcohol + 2 EO/1 PO 86.5 89.6 M14 Benzyl alcohol + 1 EO/2 PO 87.2 89.6 CM1 Benzyl alcohol + 3 PO 78.6 88.7 CM2 Benzyl alcohol + 6 PO 81.6 87.4

[0102] Curable compositions comprising the modifiers according to the invention show comparable evolution of heat after 2 days to the composition comprising benzyl alcohol. CM1 and CM2 having propoxy fragments are distinctly inferior in terms of initial hardness.

EXAMPLE 6

Moisture Sensitivity

[0103] A measure used for the moisture sensitivity of an epoxy coating is the tendency to carbamate formation. For this purpose, a small piece of sponge is soaked with water, the sponge is placed onto the coating and a bull's-eye (glass hemisphere) is mounted above it. The surface is assessed at intervals. The carbamate formed on the surface has a whitish appearance. Assessment is made on a scale from 1 (very significant carbamate formation) to 5 (no carbamate formation).

[0104] Curable composition II for production of the epoxy coating

TABLE-US-00010 Proportion Epikote 828, binder from Hexion .sup. 20 g M1, 2, 3, 5-14, CM1-2, benzyl alcohol   1 g Vestamin IPD, hardener from Evonik 4.54 g Resource Efficiency GmbH

[0105] The binder was initially charged in PE cups, the inventive modifier or benzyl alcohol or comparative examples was metered in, and the mixtures were each incorporated in a Hauschild Speedmixer at 1000 rpm for 1 min. The hardener was weighed in and the curable compositions were stirred in the Speedmixer at 2000 rpm for 1 min. This was used to cast a slab of layer thickness about 5 mm. Carbamate formation was assessed after 1, 2 and 7 days.

TABLE-US-00011 TABLE 6 Carbamate formation on a coating comprising inventive modifiers compared to benzyl alcohol Composition II after after after comprising Structure 1 d 2 d 7 d Benzyl Benzyl alcohol 5 5 5 alcohol M1 Benzyl alcohol + 3 EO 5 5 5 M1Ac Benzyl alcohol + 3 EO, 3 3 3 acetylated M1Me Benzyl alcohol + 3 EO, 2 2 3 methylated M2 Benzyl alcohol + 6 EO 1 4 5 M3 Benzyl alcohol + 3 EO/3 PO 2 4 4 M5 Benzyl alcohol + 2 EO/2 PO 1 2 5 M5Ac Benzyl alcohol + 2 EO/2 PO, 2 3 3 acetylated M5Me Benzyl alcohol + 2 EO/2 PO, 2 2 3 acetylated M6 Benzyl alcohol + 1 EO/5 PO 3 4 5 M7 Benzyl alcohol + 2 EO/4 PO 3 3 5 M8 Benzyl alcohol + 1 EO/3 PO 2 4 4 M9 Benzyl alcohol + 1 PO + 3 EO 5 5 5 M10 Benzyl alcohol + 3 EO + 1 PO 5 5 5 M11 Benzyl alcohol + 1 EO/3 PO/2 3 3 3 BO M12 Benzyl alcohol + 1 EO/3 PO/2 3 2 3 SO M13 Benzyl alcohol + 2 EO/1 PO 5 5 5 M14 Benzyl alcohol + 1 EO/2 PO 3 4 4 CM1 Benzyl alcohol + 3 PO 2 2 3 CM2 Benzyl alcohol + 6 PO 1 2 3

[0106] Coatings comprising inventive modifiers with ethoxy fragments show comparable moisture sensitivity to the coating comprising benzyl alcohol. Comparative examples comprising propoxy fragments only are distinctly inferior.