Binding agent systems

Abstract

The invention relates to coatings which can be obtained by adding mercapto groups to acrylates and/or by a radiation curing process, said coatings having good properties, to methods for producing same, and to the use thereof.

Claims

1. A coating composition comprising at least one compound (S) having at least two α-(1′-hydroxyalkyl)acrylate groups, optionally at least one compound (S1) having one α-(1′-hydroxyalkyl)acrylate group, at least one compound (C) which carries at least two thiol groups, optionally at least one reactive diluent (D) having a number-average molecular weight M.sub.n of less than 1000 g/mol and having at least two (meth)acrylate groups, optionally at least one catalyst (E) which is able to accelerate the addition of thiol groups onto acrylate groups, and optionally at least one photoinitiator (F).

2. The coating composition according to claim 1, wherein compound (S) comprises at least one compound (S2) obtained by reaction of a polyfunctional acrylate (IV) with a monofunctional carbonyl compound (II) to form compound (V) ##STR00011## or by reaction of a monofunctional acrylate (I) with a carbonyl compound (VI) having a functionality of two or more to form compound (VII) ##STR00012## in which R.sup.1, R.sup.2, and R.sup.3 independently of one another are C.sub.1-C.sub.18-alkyl, C.sub.2-C.sub.18-alkyl, C.sub.2-C.sub.18-alkenyl, C.sub.6-C.sub.12-aryl, C.sub.5-C.sub.12-cycloalkyl, or a five- to six-membered heterocycle with oxygen, nitrogen and/or sulfur atoms, wherein C.sub.2-C.sub.18-alkyl is optionally interrupted by one or more oxygen atoms and/or sulfur atoms and/or by one or more substituted or unsubstituted imino groups, wherein C.sub.1-C.sub.18-alkyl, C.sub.2-C.sub.18-alkenyl, C.sub.6-C.sub.12-aryl, C.sub.5-C.sub.12-cycloalkyl are optionally substituted in each case by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and/or heterocycles, R.sup.2 and/or R.sup.3 additionally are hydrogen, C.sub.1-C.sub.18-alkoxy optionally substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and/or heterocycles, or —COOR.sup.4, R.sup.2 may additionally, together with R.sup.1, form a ring, in which R.sup.2 is a carbonyl group, wherein the group COOR.sup.1 and R.sup.2 together form an acid anhydride group —(CO)—O—(CO)—, R.sup.4 has the same definition as listed for R.sup.1, but may be different from R.sup.1, R.sup.5 and R.sup.6 independently of one another are hydrogen, C.sub.1-C.sub.18-alkyl, C.sub.2-C.sub.18-alkyl, C.sub.2-C.sub.18-alkenyl, C.sub.6-C.sub.12-aryl, C.sub.5-C.sub.12-cycloalkyl, a five- to six-membered heterocycle with oxygen, nitrogen and/or sulfur atoms, or together form a ring, wherein C.sub.2-C.sub.18-alkyl is optionally interrupted by one or more oxygen atoms and/or sulfur atoms and/or by one or more substituted or unsubstituted imino groups, wherein C.sub.1-C.sub.18-alkyl, C.sub.2-C.sub.18-alkenyl, C.sub.6-C.sub.12-aryl, C.sub.5-C.sub.12-cycloalkyl are optionally substituted in each case by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and/or heterocycles, n is a positive integer from 2 to 10, R.sup.7 is an n-valent organic radical having 1 to 50 carbon atoms, which are unsubstituted or substituted by halogen, C.sub.1-C.sub.8-alkyl, C.sub.2-C.sub.8-alkenyl, carboxyl, carboxy-C.sub.1-C.sub.8-alkyl, C.sub.1-C.sub.20-acyl, C.sub.1-C.sub.8-alkoxy, C.sub.6-C.sub.12-aryl, hydroxyl or hydroxyl-substituted C.sub.1-C.sub.8-alkyl, and/or have one or more —(CO)—, —O(CO)O—, —(NH)(CO)O—, —O(CO)(NH)—, —O(CO)—, or —(CO)O— groups, and R.sup.8 is C.sub.6-C.sub.12-arylene, C.sub.3-C.sub.12-cycloalkylene, C.sub.1-C.sub.20-alkylene, C.sub.2-C.sub.20-alkylene, or a single bond, wherein R.sup.8 is unsubstituted or substituted by halogen, C.sub.1-C.sub.8-alkyl, C.sub.2-C.sub.8-alkenyl, carboxyl, carboxy-C.sub.1-C.sub.8-alkyl, C.sub.1-C.sub.20-acyl, C.sub.1-C.sub.8-alkoxy, C.sub.6-C.sub.12-aryl, hydroxyl or hydroxyl-substituted C.sub.1-C.sub.8-alkyl, wherein C.sub.2-C.sub.20-alkylene is interrupted by one or more oxygen atoms and/or sulfur atoms and/or by one or more substituted or unsubstituted imino groups and/or by one or more —(CO)—, —O(CO)O—, —(NH)(CO)O—, —O(CO)(NH)—, —O(CO)—, or —(CO)O— groups.

3. The coating composition according to claim 2, wherein compound (IV) is selected from the group consisting of ethylene glycol diacrylate, 1,2-propanediol diacrylate, 1,3-propanediol diacrylate, 1,4-butanediol diacrylate, 1,3-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, neopentyl glycol diacrylate, 1,1-cyclohexanedimethanol diacrylate, 1,2-cyclohexanedimethanol diacrylate, 1,3-cyclohexanedimethanol diacrylate, 1,4-cyclohexanedimethanol diacrylate, 1,2-cyclohexanediol diacrylate, 1,3-cyclohexanediol diacrylate, 1,4-cyclohexanediol diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane pentaacrylate, ditrimethylolpropane hexaacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerol diacrylate, glycerol triacrylate, diacrylates of sugar alcohols, sorbitol, mannitol, diglycerol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol, isomalt, polyester polyols, polyetherols, polyTHF having a molar mass of between 162 and 2000, poly-1,3-propanediol having a molar mass of between 134 and 1178, or polyethylene glycol having a molar mass of between 106 and 898, polyacrylates of sugar alcohols, sorbitol, mannitol, diglycerol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol, isomalt, polyester polyols, polyetherols, polyTHF having a molar mass of between 162 and 2000, poly-1,3-propanediol having a molar mass of between 134 and 1178, or polyethylene glycol having a molar mass of between 106 and 898, urethane acrylates and polycarbonate acrylates.

4. The coating composition according to claim 2, wherein compounds (II) and (VI) are aromatic aldehdyes.

5. The coating composition according to claim 1, wherein compound (S) comprises at least one compound (Sz) obtainable by reaction of at least one difunctional carbonyl compound (A2) and/or at least one more-than-difunctional carbonyl compound (Ax) with at least one difunctional acrylate compound (B2) and/or at least one more-than-difunctional acrylate compound (By).

6. The coating composition according to claim 5, wherein compound (S) comprises at least one compound (Sz) obtainable by reaction of at least one difunctional carbonyl compound (A2) with at least one difunctional acrylate compound (B2).

7. The coating composition according to claim 5, wherein compound (A2) is selected from the group consisting of glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, capronaldehyde, furan-2,5-dialdehyde, pyrrole-2,5-dialdehyde, pyridine-2,6-dialdehyde, phthalaldehyde, isophthalaldehyde, and terephthalaldehyde.

8. The coating composition according to claim 5, wherein compound (B2) is selected from the group consisting of ethylene glycol diacrylate, 1,2-propanediol diacrylate, 1,3-propanediol diacrylate, 1,4-butanediol diacrylate, and 1,6-hexanediol diacrylate.

9. The coating composition according to claim 5, wherein compound (By) is selected from the group consisting of trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, triacrylate of singly to vigintuply ethoxylated trimethylolpropane, and tetraacrylate of singly to vigintuply ethoxylated pentaerythritol.

10. The coating composition according to claim 1, wherein the compounds (C) are compounds (C1) of the formula ##STR00013## or compounds (C2) of the formula ##STR00014## or compounds (C3) of the formula ##STR00015## in which Z.sup.1, Z.sup.2, Z.sup.3, Z.sup.4, Z.sup.5, and Z.sup.6 are each independently of one another a single bond or a radical of the formula —(C═O)—R.sup.3—S—, R.sup.3 is a divalent C.sub.1- to C.sub.6-alkylene radical, p, q, r, s, t, and u, in each case independently of one another, are zero or a positive integer from 1 to 5, each X.sub.i for i=1 to p, 1 to q, 1 to r, 1 to s, 1 to t, and 1 to u, independently of one another, is selected from the group consisting of —CH.sub.2—CH.sub.2—O—, —CH.sub.2—CH(CH.sub.3)—O—, —CH(CH.sub.3)—CH.sub.2—O—, —CH.sub.2—C(CH.sub.3).sub.2—O—, —C(CH.sub.3).sub.2—CH.sub.2—O—, —CH.sub.2—CHVin-O—, —CHVin-CH.sub.2—O—, —CH.sub.2—CHPh-O—, and —CHPh-CH.sub.2—O—, in which Ph is phenyl and Vin is vinyl, with the proviso that in the case of the compounds (C1) at least four of the radicals Z.sup.1 to Z.sup.6 are a group of the formula —(C═O)—R.sup.3—S— and, in the case of the compounds (C2) and (C3), at least three radicals Z.sup.1 to Z.sup.4 are a group of the formula —(C═O)—R.sup.3—S—.

11. The coating composition according to claim 1, wherein the compounds (C) are compounds (C4) with a functionality of two or three, of the formula ##STR00016## in which R.sup.1 and R.sup.2, each independently of one another, are hydrogen or a C.sub.1- to C.sub.4-alkyl radical, R.sup.4 is methylene or 1,2-ethylene, k, l, m, and n, in each case independently of one another, are zero or a positive integer from 1 to 5, each Y.sub.i for i=1 to k, 1 to 1, 1 to m, and 1 to n, independently of one another, is selected from the group consisting of —CH.sub.2—CH.sub.2—O—, —CH.sub.2—CH(CH.sub.3)—O—, —CH(CH.sub.3)—CH.sub.2—O—, —CH.sub.2—C(CH.sub.3).sub.2—O—, —C(CH.sub.3).sub.2—CH.sub.2—O—, —CH.sub.2—CHVin-O—, —CHVin-CH.sub.2—O—, —CH.sub.2—CHPh-O—, and —CHPh-CH.sub.2—O—, in which Ph is phenyl and Vin is vinyl.

12. The coating composition according to claim 1, wherein compound (C) is selected from the group consisting of ethylene glycol di(3-mercaptopropionate) (GDMP), trimethylolpropane tri(3-mercaptopropionate) (TMPMP), trimethylolpropane trimercaptoacetate (TMPMA), 3-mercaptopropionic ester of poly-1,2-propylene glycol with a molar mass of 500 to 2500 g/mol, 3-mercaptopropionic ester of ethoxylated trimethylolpropane with a molar mass of up to 1500 g/mol, pentaerythritol tetra(3-mercaptopropionate) (PETMP), pentaerythritol tetramercaptoacetate (PETMA), dipentaerythritol tetra(3-mercaptopropionate), dipentaerythritol tetramercaptoacetate, dipentaerythritol penta(3-mercaptopropionate), dipentaerythritol pentamercaptoacetate, dipentaerythritol hexa(3-mercaptopropionate), dipentaerythritol hexamercaptoacetate, ditrimethylolpropane tetra(3-mercaptopropionate), ditrimethylolpropane tetramercaptoacetate, and their alkoxylated, ethoxylated and/or propoxylated products.

13. The coating composition according to claim 1, wherein the catalyst (E) is selected from the group consisting of primary amines, secondary amines, and tertiary amines, primary phosphines, secondary phosphines, and tertiary phosphines, quaternary ammonium salts, phosphonium salts, imines, and iminium salts.

14. A process for utilizing the coating composition according to claim 1 as an adhesive.

15. A method comprising curing the coating composition according to claim 1, wherein the ambient temperature is not more than 5° C.

Description

EXAMPLES

(1) Preparation of Inventive Products S

(2) Adduct (A): An oligomeric adduct (Sz type) of 1,4-butanediol diacrylate (Laromer® BDDA, BASF SE) and terephthalaldehyde:

(3) DABCO (0.075 mol; 8.413 g) was added to a suspension of 1,4-butanediol diacrylate (1.800 mol; 356.788 g) and terephthalaldehyde (1.500 mol; 201.198 g) in tetrahydrofuran (THF, 300 mL). The resulting mixture was stirred at 60° C. for 48 hours. After that time, THF was removed under a low vacuum. The remaining mixture was taken up in ethyl acetate and washed with 10% strength HCl in order to remove residues of the catalyst. The organic fraction was then dried over magnesium sulfate (MgSO.sub.4) and filtered, and the solvent was removed under reduced pressure. For further purification, the mixture was treated at 80° C. and 1 mbar for 12 hours.

(4) Gel permeation chromatography (GPC) in THF with PMMA standard gave an M.sub.w of 1100 g/mol and an M.sub.n of 910 g/mol. The product was a clear, yellow-colored, viscous liquid.

(5) Further possibilities employed successfully for removal or deactivation of the catalyst were filtration of the reaction mixture over solid polyacrylic acid (e.g., SOKALAN® products, BASF SE), or neutralization of the catalyst with an acid, such as benzoic acid or toluenesulfonic acid, for example.

(6) A further alternative possibility was the use of the phosphine catalyst diphenylmethylphosphine (0.075 mol).

(7) Adduct (B): Adduct (S2 type) of benzaldehyde and Laromer® BDDA:

(8) 3-Hydroxyquinuclidine (0.125 mol, 15.898 g) was added to a mixture consisting of 1,4-butanediol diacrylate (1.000 mol, 198.216 g) and benzaldehyde (1.000 mol, 106.122 g) and the mixture was stirred at 50° C. for 24 hours. Then diethyl ether was added and the organic phase was washed first with 10% strength aqueous HCl and then with saturated sodium hydrogensulfate (NaHSO.sub.3) solution. The organic fraction was subsequently dried over MgSO.sub.4 and filtered, and the solvent was removed under reduced pressure. The product was obtained as a clear liquid.

(9) Adduct (C): Adduct (S1 type) of benzaldehyde with ethyl acrylate:

(10) 3-Hydroxyquinuclidine (0.050 mol, 6.359 g) was added to a mixture consisting of ethyl acrylate (1.000 mol, 100.116 g), benzaldehyde (1.000 mol, 106.122 g), and ethanol (10 ml) and the mixture was stirred at 50° C. for 72 hours. Then diethyl ether was added and the organic phase was washed first with 10% strength aqueous HCl and then with saturated NaHSO.sub.3 solution. The organic fraction was subsequently dried over MgSO.sub.4 and filtered, and the solvent was removed under reduced pressure. The product was obtained as a clear liquid.

(11) Adduct (D): An oligomeric adduct (Sz type) of neopentyl glycol diacrylate with terephthalaldehyde:

(12) 3-Hydroxyquinuclidine (0.005 mol; 0.636 g) was added to a suspension of neopentyl glycol diacrylate (0.110 mol; 23.346 g) and terephthalaldehyde (0.100 mol; 13.413 g) in THF (300 mL) and the resulting mixture was stirred at 60° C. for 48 hours. Following the removal of the solvent, the residue was taken up in dichloromethane and the organic phase was washed first with 10% strength aqueous HCl, then with saturated NaHSO.sub.3 solution. The organic fraction was then dried over MgSO.sub.4 and filtered, and the solvent was removed under reduced pressure. For further purification, the mixture was treated at 80° C. and 1 mbar for 12 hours.

(13) GPC in THF with PMMA standards gave an M.sub.w of 640 g/mol and an M.sub.n of 570 g/mol. The product was a clear, yellow-colored, viscous liquid.

(14) Adduct (E): Preparation of the adduct (S2 type) from pentaerythritol triacrylate and benzaldehyde:

(15) 100.0 g (0.335 mol) of pentaerythritol triacrylate were mixed with 106.7 g of benzaldehyde (1.0 mol) and 3.37 g of DABCO (30 mmol) and the mixture was stirred at 60° C. for 48 hours. The mixture was then taken up in THF and the catalyst was removed by filtration over solid polyacrylic acid (SOKALAN® PA 40, BASF SE). THF was then removed under reduced pressure. The resulting product was a clear liquid.

(16) Adduct (F): Preparation of the adduct (S2 type) from dipentaerythritol penta-/hexaacrylate and benzaldehyde:

(17) 17.9 g (0.060 mol) of dipentaerythritol penta-/hexaacrylate were mixed with 19.1 g of benzaldehyde (0.180 mol) and 0.760 g of 3-HQD (6.00 mmol of hydroxyquinuclidine) and the mixture was stirred at 60° C. for 96 hours. The catalyst was then removed by neutralization with benzoic acid. The resulting product was a clear liquid.

(18) Curing of adducts S: Examples of different formulations

(19) All of the formulations indicated were cured at room temperature and are based on the above-prepared adducts (A) to (F). Higher temperatures during curing are possible, leading to more rapid curing and to materials having an ultimate hardness which is higher by approximately 20%.

Example 1: Formulation of a Two-Component System as Structural Adhesive

(20) 9 g of adduct (A)=component 1

(21) 10.4 g of pentaerythritol tetrakis(3-mercaptopropionate) (crosslinker) mixed with 80 mg of N-methyldicyclohexylamine (catalyst)=component 2

(22) Component 1 was mixed with component 2. After 2 hours of curing at room temperature, the system had a Shore A hardness of 76 and after curing for 14 days it had a Shore D hardness of 70. A tensile test on the cured material after 14 days gave a tensile strength of 10.1 N/mm.sup.2 with an elongation of 10-40%. The test specimens measured were dumbbell specimens to ISO 527. ASTM D 638, in the Z 250 SN (AllroundLine) instrument.

(23) Tensile shear tests on the cured resin after 1 week of storage at room temperature on various substrates gave the following tensile adhesive strengths:

(24) Polypropylene/polypropylene: 0.5 N/mm.sup.2

(25) Glass/glass: 1.3 N/mm.sup.2

(26) Aluminum/aluminum: 1.5 N/mm.sup.2

(27) Wood/wood: 2.5 N/mm.sup.2

(28) Steel/steel: 5.5 N/mm.sup.2

(29) Concrete/concrete: >3.5 N/mm.sup.2 (concrete broke cohesively)

(30) Measurement took place with the Z 250 SN (AllroundLine) instrument, pretensioning force=2 N, test speed=0.5 mm/min, bond area 360 mm.

(31) A further particular feature of this adhesive formulation is that it was curable to a tack-free state at −4′C.

(32) Comparative experiments with epoxy resin-based systems of the prior art (UHU Endfest 3000 (from UHU) and Sikadur® 31 CF Baukieber (construction adhesive from SIKA) showed that it is not possible to cure these conventional systems below 0° C.

Example 2: Formulation with Reactive Diluent

(33) 4.5 g of adduct (A) and 4.5 g of Laromer® BDDA (1,4-butanediol diacrylate, reactive diluent)=component 1

(34) 10.4 g of pentaerythritol tetrakis(3-mercaptopropionate) (crosslinker) and 80 mg of N-methyldicyclohexylamine (catalyst)=component 2

(35) Component 1 was mixed with component 2. After 5 hours of curing at room temperature, the material had a Shore A hardness of 61. The material described here is somewhat softer than the formulation of example 1, but the system is substantially more fluid and can be filled to a higher level with aggregates, which is advantageous, for example, for use as a leveling compound in the construction sector.

Example 3: Formulation of a Filled System

(36) 4.5 g of adduct (A), 4.5 g of Laromer® BDDA (1,4-butanediol diacrylate, reactive diluent), 19.4 g of calcium carbonate (CaCO.sub.3) powder (filler), Tego Airex® 940 defoamer=component 1

(37) 10.4 g of pentaerythritol tetrakis(3-mercaptopropionate) (crosslinker) mixed with 80 mg of N-methyldicyclohexylamine (catalyst)=component 2

(38) Component 1 was mixed with component 2. After 5 hours of curing at room temperature, the material had a Shore A hardness of 85 (60 Shore D).

Example 4: Formulation of a Soft Material (for Example, for Sealants, Waterproofing Membranes, Fuel-Resistant Coatings)

(39) 5 g of adduct (A)=component 1

(40) 15 g of Thioplast® G44 polysulfide from AkzoNobel (polysulfide-based crosslinker) with 110 mg of N-methyldicyclohexylamine (catalyst)=component 2.

(41) Component 1 was mixed with component 2. After 16 hours of curing at room temperature, the material had a Shore A hardness of 46.

Example 5: Curing of an Oligomeric Adduct Based on Neopentyl Glycol Diacrylate

(42) 9 g of adduct (D)=component 1

(43) 10 g of pentaerythritol tetrakis(3-mercaptopropionate) (crosslinker) with 240 mg of N-methyldicyclohexylamine (catalyst)=component 2.

(44) Component 1 was mixed with component 2. After 2 hours of curing at room temperature, the material had a Shore A hardness of 80 (57 Shore D).

Example 6: Curing of a Monomeric Adduct

(45) 7.3 g of adduct (B)=component 1

(46) 5.5 g of pentaerythritol tetrakis(3-mercaptoproplonate) (crosslinker) with 50 mg of N-methyldicyclohexylamine (catalyst)=component 2.

(47) Component 1 was mixed with component 2. After 2 days of curing at room temperature, the material had a Shore A hardness of 59.

Example 7: Formulation of a Transparent, Silica-Based Hybrid Material

(48) 6 g of adduct (B), 6 g of pentaerythritol triacrylate (reactive diluent, network former), and 0.5 g of water=component 1

(49) 14.4 g of pentaerythritol tetrakis(3-mercaptopropionate) (crosslinker), 4 g of mercaptopropyltriethoxysilane, 50 mg of N-methyldicyclohexylamine (catalyst) and 120 mg of TEGO Airex® 940 (deaerating agent)=component 2

(50) Component 1 was mixed with component 2. After 1 day of curing at room temperature, the hybrid material had a Shore A hardness of 71. The material was clear and transparent.

Example 8: Curing of a Monomeric Adduct Based on Dipentaerythritol Penta-/Hexaacrylate

(51) 9.02 g of adduct (F)=component 1

(52) 10.53 g of pentaerythritol tetrakis(3-mercaptopropionate) (crosslinker)

(53) with 200 mg of N-methyldicyclohexylamine (catalyst)=component 2

(54) Component 1 was mixed with component 2.

(55) After 2 days of curing at 60° C., the material had a shore A hardness of 50.

Example 9: Comparative Experiment of an Inventive System with a Prior-Art, Acrylate-Based System; Both Systems Cured with Thiol

(56) The comparative system according to the prior art selected was pentaerythritol triacrylate as acrylate component, since this molecule can be cured to give solid materials. Moreover, it permits comparison with an inventive adduct having the same number of double bonds and hence the same SH to C═C ratio in the formulation. Accordingly, the adhesive force of the materials can be compared directly.

(57) (X)=adduct (E)

(58) (Y)=pentaerythritol triacrylate

(59) (X) and also (Y) were crosslinked with pentaerythritol tetrakis(3-mercaptopropionate) with an SH/C═C ratio of 0.94, and a determination was made, for the purpose of example, of the adhesion to steel. Tensile adhesion anchors were pulled in accordance with DIN EN 13596, and determinations were made of the maximum tensile adhesion strains.
After 1 day of curing at room temperature:
(X) based resin: 0.270 N/mm.sup.2 (average of 6 measurements)
(Y) based resin: 0.181 N/mm.sup.2 (average of 6 measurements)
After 14 days of curing at room temperature:
(X) based resin: 0.297 N/mm.sup.2 (average of 3 measurements)
(Y) based resin: 0.166 N/mm.sup.2 (average of 3 measurements)
As a result, the use of the inventive system in the addition-crosslinking systems described leads to significantly higher adhesion properties as compared with the acrylate system according to the prior art.