NCO-Free Compounds and Usage Thereof in a Curable Composition

Abstract

The invention relates to a compound comprising at least two (NHCO) groups and at least two (CO)CCR.sup.1 groups, wherein R.sup.1 represents hydrogen or a group having from 1 to 12 carbon atoms; a curable composition comprising a first unit comprising at least two (NHCO) groups, a second unit comprising at least two (CO)CCR.sup.1 groups, and a catalyst; and the use of the composition as an adhesive, coating, casting composition or as sealant.

Claims

1. A compound comprising at least two (NHCO) groups and at least two (CO)CCR.sup.1 groups, wherein R.sup.1 represents hydrogen or a group having from 1 to 12 carbon atoms.

2. The compound according to claim 1, wherein R.sup.1 represents hydrogen or CH.sub.3.

3. The compound according to claim 1, wherein the (NHCO) groups are provided by urea and/or urethane groups.

4. The compound according to claim 1, wherein the (NHCO) groups are provided by urethane groups.

5. The compound according to claim 1, obtained by a) reacting a polyisocyanate with at least two isocyanate groups with a polyol or a polyamine or a mixture thereof to form an intermediate, wherein the molar ratio of the NCO groups of the polyisocyanate to the sum of hydroxyl groups, primary amino groups and secondary amino groups of the polyol and polyamine is less than 1; and b) reacting a compound of the formula R.sup.2O(CO)CCR.sup.1 with the intermediate of step a) in molar excess to the sum of hydroxyl groups, primary amino groups and secondary amino groups of the intermediate, wherein R.sup.1 represents hydrogen or a group having from 1 to 12 carbon atoms, and R.sup.2 represents hydrogen or a group having from 1 to 4 carbon atoms.

6. The compound according to claim 5, wherein the polyol is selected from a group comprising polyether polyols, polyether polyol block-copolymers, polyester polyols, polyester polyol block-copolymers or mixtures thereof and mixtures thereof

7. The compound according to claim 5, wherein the polyol is selected from a group comprising polyethylene glycol, polypropylene glycol and polytetrahydrofuran, and mixtures thereof

8. The compound according to claim 5, wherein the number average molar weight (M.sub.n) of the polyol/polyamine from 1000 to 5000 g/mol.

9. The compound according to claim 5, wherein the polyisocyanate is selected from a group comprising 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2-diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4-methylene dicyclohexyl diisocyanate, 2,4-methylene dicyclohexyl diisocyanate, 2,2-methylene dicyclohexyl diisocyanate, and mixtures thereof.

10. A curable composition comprising: a first unit comprising at least two (NHCO) groups, a second unit comprising at least two (CO)CCR.sup.1 groups, and a catalyst, wherein R.sup.1 represents hydrogen or a group having 1 to 12 carbon atoms.

11. The curable composition according to claim 10, wherein the (NHCO) groups are provided by urea and/or urethane groups.

12. The curable composition according to claim 10, wherein the first and the second units are part of one compound.

13. The curable composition according to claim 10, wherein the first and the second unit are part of different compounds.

14. The curable composition according to claim 10, wherein the first and the second unit are part of different compounds and the first unit is part of a thermoplastic polyurethane.

15. The curable composition according to claim 10, wherein the catalyst is a secondary or tertiary amine.

16. The curable composition according to claim 10, wherein the catalyst is selected from the group consisting of 1,4-diazabicyclo[2.2.2]octane, tetramethylethylenediamine, N,N-diisopropylethylamine, triethanolamine, tris(2-pyridylmethyl)amine, tributylamine, 4-dimethylaminophenol, N-ethyl-N-methyl propylamine, N-methyl piperidine, N-butyl-4-hydroxy piperidine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, imidazoline, benzimidazole, dimethylamino ethanol, pirrole, morpholine, piperidine, piperazine, indole, and mixtures thereof.

17. The curable composition according to claim 10, wherein the catalyst is 1,4-diazabicyclo[2.2.2]octane.

18. The curable composition according to claim 10, wherein the second unit is provided by a compound that is the reaction product of a polyether polyol with at least two OH groups with a compound of the formula R.sup.2O(CO)CCR.sup.1 in a quantity at least equivalent to two OH groups of the polyether polyol, wherein R.sup.1 represents hydrogen or a group having 1 to 12 carbon atoms, and R.sup.2 represents hydrogen or a group having 1 to 4 carbon atoms.

19. The curable composition according to claim 18, wherein the number average molar mass (M.sub.n) of the compound comprising the second unit is from 500 to 1500 g/mol.

20. An adhesive, coating, casting composition or sealant comprising the composition of claim 10.

Description

EXAMPLES

[0053] In some of the following examples, elongation at break, tensile strength and the decomposition temperature of cured compositions are indicated.

[0054] In the context of the invention, elongation at break refers to the ratio between changed length and initial length after breakage of a tested material (the cured composition). It expresses the capability of a material to resist changes of shape without crack formation. Elongation at break is determined by tensile testing in accordance with EN ISO 527.

[0055] Tensile strength refers to the force required to pull a material (the cured composition) to the point where it breaks.

[0056] The decomposition temperature (Td) of the cured compositions was measured using thermogravimetric analysis (TGA). At Td a weight loss of 5% is observed. The decomposition temperature was recorded by heating 10 C./min.

Synthesis of the Inventive Compounds

Example 1

Synthesis of Isophorone Diisocyanate (IPDI) Conjugated PTHF Diester (Hereafter PITHF)

[0057] 40 g of polytetrahydrofurane (PTHF, Mn=1000 g/mol) was added into a 250 mL 3-neck round-bottom flask and heated at 120 C. under vacuum for 1.5 h. Then, the temperature was cooled down to 90 C. and the reaction mixture was purged with nitrogen (or a comparable inert gas), and 4.45 g of isophorone diisocyanate (IPDI) was added, and the temperature was increased up to 110 C. The reaction mixture was stirred for at least 12 h, until all the NCO groups were consumed, as it was ascertained by titration (the free isocyanate content can, for example, easily be measured by titration of the free isocyanate with an amine and back-titration of the unreacted amine).

[0058] 42.6 g of the intermediate was added to a round-bottom flask equipped with a Dean-Stark apparatus, together with 0.43 g of p-toluenesulfonic acid (p-TsOH) solved in 100 mL of toluene. The mixture was stirred at 40 to 50 C. until a homogeneous solution was observed, then 5.37 g (4.7 mL) of propiolic acid was added. The final solution was heated up to 140 C. and stirred at this temperature for 48 hours. When the reaction was finished (as detected by .sup.1H-NMR) the mixture was cooled down to room temperature, and diluted with another 100 ml of toluene. The organic solution was then washed three times with a solution of sodium bicarbonate in water (2 wt % of bicarbonate in water), until the excess of propiolic acid was neutralized. The organic phase was subsequently treated with brine, dried over magnesium sulfate, filtered and concentrated in vacuum, resulting in the inventive compound.

Example 2

Synthesis of Hexamethylene Diisocyanate (HDI) Conjugated PTHF Diester (Hereafter PHTHF)

[0059] 50 g of PTHF (Mn=1000 g/mol) was added into a 250 mL 3-neck round-bottom flask and heated at 120 C. under vacuum for 1.5 h. Then, after the temperature was cooled down to 90 C. and purged with nitrogen, and 4.21 g of hexamethylene diisocyanate (HDI) was added, and the temperature was increased up to 110 C. The reaction mixture was stirred for at least 12 h, until all the NCO groups were consumed, as it was confirmed by titration.

[0060] 52.47 g of the intermediate was added to a round-bottom flask equipped with a Dean-Stark apparatus, together with 0.52 g of p-toluenesulfonic acid (p-TsOH) solved in 100 mL of toluene. The mixture was stirred at 40 to 50 C. until a homogeneous solution was observed, and then, 6.38 g (5.67 mL) of propiolic acid was added. The final solution was heated up to 140 C. and stirred at this temperature for 48 hours. When the reaction was finished (as detected by .sup.1H-NMR) the mixture was cooled down to room temperature, and diluted with another 100 ml of toluene. The organic solution was then washed three times with a solution of sodium bicarbonate in water (2% of bicarbonate in water), until the excess of propiolic acid was neutralized. The organic phase was subsequently treated with brine, dried over magnesium sulfate, filtered and concentrated in vacuum, resulting in the inventive compound. Final yield: 70%.

Inventive Composition/Curing of the composition

Example 3

Composition with Compound from Example 1 (PITHF) and Additional Compound.

[0061] 2 g of the compound from example 1 and 0.048 g of an additional compound comprising three O(CO)CCH groups (Mn about 1000 g/mol) was added into a solution of DABCO (0.0058 g) in ethyl acetate (0.4 ml), and the mixture left exposed to the air at room temperature. After 2 hours, a brown, not sticky polymer was obtained (the cured inventive composition).

[0062] The additional compound was obtained by reacting a glycerine-propoxylated polyol with propiolic acid, wherein the OH:propiolic acid ratio is at least 1:1. The glycerine propoxylated polyol is produced by reacting glycerine with propylene oxide. Glycerine acts as the initiator.

[0063] Tensile tests (tensile speed 50 mm/min):

[0064] Elongation at break: 330%

[0065] Tensile strength: 3.38 MPa

Example 4

Composition with Compound from Example 1 (PITHF)

[0066] 2 g of compound from example 1 was added into a solution of DABCO (0.005 g) in ethyl acetate (0.4 ml), and the mixture left exposed to the air at room temperature. After 2 hours, a pale brown, not sticky polymer was obtained.

[0067] Tensile tests (tensile speed 50 mm/min):

[0068] Elongation at break: 123%

[0069] Tensile strength: 1.66 MPa

Example 5

Composition with Compound from Example 2 (PHTHF)

[0070] 2 g of compound from example 2 was added into a solution of DABCO (0.005 g) in ethyl acetate (0.4 ml), and the mixture left exposed to the air at room temperature. After 2 hours, a pale brown, not sticky polymer was obtained.

[0071] Tensile tests (tensile speed 50 mm/min):

[0072] Elongation at break: 60%

[0073] Tensile strength: 1.67 MPa

[0074] Thermostability and Mechanical Properties

[0075] Decomposition Temperatures (Td)

[0076] The following table shows the decomposition temperatures of cured compositions in accordance with some of the examples given above, and two further cured inventive compositions not described in detail but prepared in accordance with examples 4 and 5.

TABLE-US-00001 Decomposition Example temperature ( C.) 5, PHTHF 2300 332.8 4, PHTHF 2300 318.3 cured composition on the basis of a 317.7 compound with IPDI as isocyanate and PTHF (Mn = 2000) as polyol cured composition on the basis of a 304.1 compound with methylene diphenyl diisocyanate (MDI) as isocyanate and PTHF (Mn = 1000) as polyol (hereafter PMTHF)

[0077] As can be seen from the table above, the decomposition temperature of the cured inventive compositions is very high, in the shown cases higher than 300 C.

[0078] Elongation at Break/Tensile Strength

[0079] In the following tables, elongation at break/tensile strength for some inventive cured compositions is shown, wherein all compositions were prepared and cured as mentioned above.

[0080] Table 1 shows the influence of the isocyanate group on these properties (when maintaining the same polyol),

[0081] Table 2 shows the influence of the molecular weight of the side chain (polyol), and

[0082] Table 3 shows the influence of a further compound comprising three O(CO)CCH groups (refer to example 1).

TABLE-US-00002 TABLE 1 Mechanical properties of cured compositions from different isocyanate conjugated PTHFs Cured composition DABCO Elongation at Tensile strength on the basis of: * Wt % break (%) (MPa) PMTHF 0.1 26 1.24 (MDI, Mn~2300) PHTHF 0.3 59 1.67 (HDI, Mn~2300) PITHF 0.3 123 1.66 (IPDI, Mn~2300) All reactions were performed using 20 wt % of EtOAc based on the weight of the polymer. The content of the base (DABCO), and the solvent (EtOAc) are referred in wt. % are referred to the quantity of prepolymer.

TABLE-US-00003 TABLE 2 Mechanical properties of cured compositions from IPDI conjugated different molecular weight PTHFs Cured composition DABCO Elongation at Tensile strength on the basis of: * Wt % break (%) (MPa) PITHF, 0.3 123 1.66 Mn~2300 PITHF, 0.16 848 2.86 Mn~4300* All reactions were performed using 20 wt % of EtOAc. *In presence of PITHF 4300, 30 wt % of EtOAc were used. The content of the base (DABCO) and the solvent (EtOAc) are referred in wt. % are referred to the quantity of prepolymer.

TABLE-US-00004 TABLE 3 Mechanical properties of cured compositions from PITHF 2300 with different contents of a further compound comprising three O(CO)CCH groups (see example 1). DABCO Elongation at Tensile strength Polymer from: * Wt % break (%) (MPa) PITHF 0.3 123 1.66 MW~2300 PITHF + further 0.3 330 3.38 compound 5 mol % PITHF + further 0.3 94 1.81 compound 10 mol % All reactions were performed using 20 wt % of EtOAc. The content of the base (DABCO), the solvent (EtOAc), and the further compound are referred in wt % are referred to the quantity of prepolymer.

[0083] As can be seen from the Tables 1 to 3 the inventive compounds/compositions/cured compositions offer a system with a very broad range of mechanical properties (elongation at break/tensile strength), i.e. with the inventive compounds/compositions/polymers a toolbox with a very broad field of applications is provided.