Curable composition having combined stabilizers

Abstract

The invention aims to improve temperature resistance for a curable composition based on a silyl-terminated polymer. This is achieved by using a combination of at least two phenolic compounds, of which one is free of thioether groups, while the other contains at least one thioether group in at least one alkyl side chain. The invention further relates to the use of the curable composition as an adhesive, sealant and/or coating substance and to the use of the combination of phenolic compounds to increase the temperature stability in curable compositions.

Claims

1. A curable composition, at least comprising A) at least one polymer with at least one end group of the general formula (I)
-An-RSiXYZ(I), where A is a divalent linking group comprising at least one heteroatom, R is a divalent hydrocarbon residue with 1-12 C atoms, and X, Y, Z are substituents on the Si atom and are, independently of one another, C.sub.1-C.sub.8 alkyl, C.sub.1-C.sub.8 alkoxy or C.sub.1-C.sub.8 acyloxy groups, wherein at least one of the residues X, Y, Z is a C.sub.1-C.sub.8 alkoxy or C.sub.1-C.sub.8 acyloxy group, and n is 0 or 1, wherein the A) at least one polymer is a polyether or a poly(meth)acrylic acid ester; B) at least one compound of the general formula (II) ##STR00009## where R.sup.1, R.sup.2 and R.sup.3 independently of one another are unsubstituted alkyl residues or organic residues comprising at least one heteroatom and encompassing at least 10 C atoms, wherein the residues R.sup.1, R.sup.2 and R.sup.3 are free from thioether groups; and C) at least one compound of the general formula (III) ##STR00010## where R.sup.4, R.sup.5 and R.sup.6 independently of one another are unsubstituted alkyl residues or linear alkyl residues comprising at least one thioether group, wherein no more than two of the residues R.sup.4, R.sup.5 and R.sup.6 is a linear alkyl residue comprising at least one thioether group; wherein the composition comprises the following components in the stated proportions by weight: TABLE-US-00004 at least one polymer with at least one end group 10-60 wt. %, of the general formula (I) at least one compound of the general formula (II) 0.05-5 wt. %, at least one compound of the general formula (III) 0.05-5 wt. %, one or more filler(s) 10-70 wt. %, one or more plasticizers 1 to 30 wt. %, one or more auxiliary substance(s) 0-10 wt. %, wherein the auxiliary substance(s) are free of curing catalysts, wherein the composition is free of fatty acid amides as a thixotrope and the proportions by weight add up to 100 wt. % and the proportions by weight are based on the total weight of the curable composition.

2. The curable composition according to claim 1, wherein the divalent linking group A in the general formula (I) is an oxygen atom, an NR group, where R is an H atom or an alkyl or aryl residue with 1 to 12 C atoms, or an amide, carbamate, urea, imino, carboxylate, carbamoyl, amidino, carbonate, sulfonate or sulfinate group.

3. The curable composition according to claim 1, wherein the residues X, Y, Z in the general formula (I), each independently of one another, are a methyl, an ethyl, a methoxy or an ethoxy group, wherein at least one of the residues is a methoxy or ethoxy group.

4. The curable composition according to claim 1, wherein R in the general formula (I) is a methylene, ethylene or n-propylene group.

5. The curable composition according to claim 1, wherein the compound of the general formula (II) is a compound of the general formula (IV) ##STR00011## where R.sup.n and R.sup.m independently of one another are unsubstituted alkyl residues, wherein at least one of the residues R.sup.n and R.sup.m comprises at least four C atoms; o and p independently of one another are integers from 1 to 8; q is an integer from 2 to 4 and A is a q-valent organic residue with 1 to 4 C atoms.

6. The curable composition according to claim 1, wherein at least two of the residues R.sup.4, R.sup.5 and R.sup.6 are each linear alkyl residues comprising at least one thioether group.

7. An adhesive, sealant, and/or coating composition comprising a curable composition according to claim 1.

8. The curable composition according to claim 1, wherein the compound of the general formula (III) is a compound of the general formula (V) ##STR00012## wherein R.sup.d is an unsubstituted alkyl residue with 1 to 8 C atoms; R.sup.b and R.sup.c, independently of one another, are linear alkyl residues with 1 to 20 C atoms; and, n and m, independently of one another, are integers from 1 to 8.

9. The curable composition according to claim 8, wherein R.sup.d is a methyl, ethyl or i-propyl group; n and m are 1; and, R.sup.b and R.sup.c each have 8 to 12 C atoms, with R.sup.b and R.sup.c comprising the same number of C atoms.

10. The curable composition according to claim 1 comprising 5 to 25 wt. % of one or more plasticizers.

Description

EXAMPLES

(1) Compositions according to Tables 1 and 2 were produced in a Speedmixer by mixing the ingredients listed there.

(2) From the compositions, S2 specimens were produced. These were subjected to storage for 42 or 84 days in a standard atmosphere (23 C., 50% relative humidity) or at 100 C. in a circulating air oven with air exchange according to the tables, with storage at 100 C. simulating long-term storage.

(3) After the storage (after storage at 100 C., 1 d reconditioning in a standard atmosphere), measurements were performed to determine the 50% and 100% modulus respectively and the tear strength, using a tensile testing machine. Specimens are considered to have long-term temperature stability if the maximum percentage deviation of their elasticity values after storage under the different conditions stated in each case is 20%.

(4) TABLE-US-00002 TABLE 1 Compositions and results Composition (data in wt. %) 1 (inv.) 2 (inv.) 3 (cp.) 4 (cp.) Polymer (STP-E 10, Wacker) 33.2 33.2 33.2 33.2 Plasticizer (Mesamoll, 15.3 15.3 15.3 15.3 Lanxess) Filler (coated, precipitated chalk) 47.6 47.6 47.6 47.6 Irganox 245 0.3 0.3 0.3 Irganox 1520 0.3 0.3 0.3 Tinuvin 770 0.3 0.3 Auxiliaries 3 3.3 3.3 3.6 Total 100 100 100 100 Test results after 42 d (standard atmosphere) 50% Modulus (N/mm.sup.2) 1.28 1.27 1.25 1.27 100% Modulus (N/mm.sup.2) 2.0 2.01 1.96 1.99 Tear strength (N/mm.sup.2) 3.32 3.29 2.99 3.18 Test results after 84 d (100 C.) 50% Modulus (N/mm.sup.2) 1.05 1.03 0.24 0.75 100% Modulus (N/mm.sup.2) 1.77 1.7 0.45 1.33 Tear strength (N/mm.sup.2) 2.67 2.79 1.19 2.41 Change comparing 84 d v. 42 d (%) 50% Modulus (N/mm.sup.2) 18 19 81 41 100% Modulus (N/mm.sup.2) 12 15 77 33 Tear strength (N/mm.sup.2) 20 15 70 24 inv. = according to the invention cp. = comparative test

(5) TABLE-US-00003 TABLE 2 Compositions and results Composition (data in wt. %) 3 (inv.) 4 (inv.) 5 (inv.) 6 (cp.) Polymer (STP-E 10, Wacker) 33.2 33.2 33.2 33.2 Plasticizer (Mesamoll, 15.3 15.3 15.0 15.3 Lanxess) Filler (coated, precipitated chalk) 39.6 39.6 39.6 39.6 Irganox 245 0.3 0.3 0.3 Irganox 1010 0.3 Irganox 1330 0.3 Irganox 1520 0.3 0.3 0.3 Tinuvin 770 0.3 0.3 0.3 0.3 Auxiliaries 11 11 11.3 11 Total 100 100 100 100 Test results after 84 d (standard atmosphere) 50% Modulus (N/mm.sup.2) 1.20 1.19 1.22 1.20 100% Modulus (N/mm.sup.2) 1.96 1.96 1.99 1.96 Tear strength (N/mm.sup.2) 3.40 3.30 3.32 3.17 Test results after 42 d (100 C.) 50% Modulus (N/mm.sup.2) 1.02 0.95 1.01 0.73 100% Modulus (N/mm.sup.2) 1.73 1.62 1.71 1.31 Tear strength (N/mm.sup.2) 3.35 3.30 3.31 2.86 Change comparing 42 d v. 84 d (%) 50% Modulus (N/mm.sup.2) 15 20 17 39 100% Modulus (N/mm.sup.2) 12 17 14 33 Tear strength (N/mm.sup.2) 1 0 0 10 inv. = according to the invention cp. = comparative test

(6) The test results show that the deviation from the initial value after long-term storage is no more than 20% throughout for the compositions according to the invention, while significantly higher deviations occur for compositions that are not according to the invention. From a comparison of compositions 3, 4 and 5 with composition 6, it becomes clear that a combination of two similar stabilizers (Irganox 245, Irganox 1010, example 6 which is not according to the invention) does not bring about the synergistic effect in terms of long-term temperature stability, in contrast to the combination of compounds of the general formula (II) and compounds of the general formula (III) according to the invention (Examples 3, 4 and 5 according to the invention).