Curable Compositions Comprising Adhesion Promoters

Abstract

The invention relates to curable compositions based on curable polymers containing a special capped adhesion promoter, and optionally a curing catalyst. These compositions have improved adhesion properties and excellent storage stability. The invention also relates to the uses thereof.

Claims

1. A curable composition comprising (A) at least one curable polymer; (B) at least one capped adhesion promoter of formula (I):
BR.sup.11SiR.sup.12.sub.q(OR.sup.13).sub.3-q (I) wherein R.sup.11 is a linear or branched alkylene group, optionally interrupted by a heteroatom; each R.sup.12 is independently selected from the group consisting of hydrogen, halogen, amino, a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloaliphatic, aryl, heteroaryl, and heteroalicyclic group or a combination thereof; each R.sup.13 is independently selected from the group consisting of a substituted or unsubstituted alkyl, alkenyl, alkynyl, or acyl group; each R.sup.14 is independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, cycloaliphatic, aryl, heteroaryl, and heteroalicyclic group or a combination thereof; q independently stands for 0, 1, or 2; and B is a nitrogen-containing group of formula (1)
NR.sup.15R.sup.16 (1) wherein R.sup.15 is selected from Si(R.sup.17).sub.3; R.sup.16 is selected from Si(R.sup.17).sub.3, hydrogen, a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloaliphatic, aryl, heteroaryl, and heteroalicyclic group or a combination thereof; and each R.sup.17 is independently selected from hydrogen, a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloaliphatic, or aryl group or a combination thereof; or wherein R.sup.15 and R.sup.16 combine to form together with the nitrogen atom to which they are attached a group of formula Si(R.sup.17).sub.2R.sup.18Si(R.sup.17).sub.2, wherein R.sup.18 is a linear or branched alkylene group; and (C) optionally at least one curing catalyst.

2. The curable composition according to claim 1, wherein the capped adhesion promoter is a silazane of formula (I) with q being 0, R.sup.11 being methylene, n-propylene or n-butylene, each R.sup.13 being methyl, ethyl or C.sub.1-C.sub.5 alkyl substituted with an amino group of the formula NR.sup.19R.sup.20 with R.sup.19 and R.sup.20 independently being selected from hydrogen, methyl, and ethyl, and B being a group of formula (1), wherein R.sup.15 is Si(R.sup.17).sub.3 and R.sup.16 is hydrogen, alkyl substituted with Si(R.sup.17).sub.3 or Si(R.sup.17).sub.3, and each R.sup.17 is independently alkyl.

3. The curable composition according to claim 1, wherein (i) the amount of polymer (A) is from about 32 to about 97% by weight, relative to the total weight of the composition; and/or (ii) the amount of capped adhesion promoter (B) is from about 0.1 to about 5% by weight, relative to the total weight of the composition; and/or (iii) the amount of the curing catalyst, if present, is from about 0.05 to 2% by weight, relative to the total weight of the composition.

4. The curable composition according to claim 1, wherein the at least one curable polymer (A) is selected from the group consisting of silane-modified polymers, silicones, polyurethanes, and epoxides.

5. The curable composition according to claim 4, wherein the at least one curable polymer is polydimethylsiloxane (PDMS).

6. The curable composition according to claim 4, wherein the curable polymer (A) comprises at least one terminal group of the formula (II):
-A-Si(R.sup.1).sub.m(R.sup.2).sub.n(R.sup.3).sub.3-(m+n) (II) wherein: A is a bond, O or a linear, branched or cyclic divalent group selected from hydrocarbon residues having 1 to 12 carbon atoms, alkylene, arylene, oxyalkylene, oxyarylene, siloxane-alkylene, siloxane-arylene, ester, amine, glycol, imide, amide, alcohol, carbonate, urethane, urea, sulfide, ether or a derivative or combination thereof; each R.sup.1 is independently selected from the group consisting of hydrogen, halogen, amino, oximino, a substituted or unsubstituted alkyl, alkenyl, alkenyloxy, alkynyl, alkylnyloxy, cycloaliphatic, cycloaliphatic-O-, aryl, aryloxy, heteroaryl, heteroaryloxy, heteroalicyclic, heteroalicyclicoxy, acyl, acyloxy group or a combination thereof; each R.sup.2 is independently a group of the general formula (2):
OYCOOR.sup.4 (2) wherein Y is a substituted or unsubstituted (hetero)aromatic group having 4 to 14 ring atoms, a substituted or unsubstituted saturated or partially unsaturated 4- to 14-membered (hetero)cyclic group or (C(R.sup.5).sub.2).sub.o; R.sup.4 is a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloaliphatic, aryl, heteroaryl, and heteroalicyclic group or a combination thereof; each R.sup.5 is independently selected from the group consisting of hydrogen, a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloaliphatic or aryl group; and o is an integer from 1 to 10; each R.sup.3 independently is a group of the general formula (3):
OYCONR.sup.6R.sup.7 (3) wherein Y is as defined above; R.sup.6 is selected from the group consisting of hydrogen, a substituted or unsubstituted alkyl, alkenyl, alkynyl cycloaliphatic, aryl, heteroaryl, and heteroalicyclic group or a combination thereof or R.sup.7; R.sup.7 is a group of the general formula (4):
R.sup.8SiR.sup.9.sub.p(OR.sup.10).sub.3-p (4) wherein R.sup.8 is an alkylene group, optionally interrupted by a heteroatom; each R.sup.9 is independently selected from the group consisting of hydrogen, halogen, amino, a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloaliphatic, aryl, heteroaryl, and heteroalicyclic group or a combination thereof; each R.sup.10 is independently selected from the group consisting of a substituted or unsubstituted alkyl, alkenyl, alkynyl, or acyl group; each p independently stands for 0, 1, or 2; m is independently 0, 1 or 2; and n is independently 1, 2, or 3, wherein the sum n+m is a maximum of 3.

7. The curable composition according to claim 6, wherein A is a bond, O or a linear or branched divalent group of the formula (CH.sub.2).sub.1-10(Si(Alk).sub.2OSi(Alk).sub.2).sub.1-10(CH.sub.2).sub.1-10, or a derivative thereof, with Alk being unsubstituted C.sub.1-10 alkyl.

8. The curable composition according to claim 6, wherein each R.sup.1 independently of one another stands for an alkyl group having 1 to 10 carbon atoms, or for an alkenyl group having 2 to 10 carbon atoms, or for an aryl group having 6 to 10 carbon atoms, or for an aryloxy group having 6 to 14 carbon atoms, or for an acyloxy group having 2 to 10 carbon atoms, or for amino; and/or each R.sup.2 independently of one another stands for a group of the formula (2), wherein R.sup.4 stands for a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and Y is a substituted or unsubstituted aromatic group having 6 carbon ring atoms, or (C(R.sup.5).sub.2).sub.o, wherein o is 1 and one of the R.sup.5 groups is hydrogen and the second R.sup.5 group is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

9. The curable composition according to claim 6, wherein the sum n+m is 3.

10. The curable composition according to claim 6, wherein the group Si(R.sup.1).sub.m(R.sup.2).sub.n(R.sup.3).sub.3-(m+n) in formula (I) is selected from methyl bis(ethyl lactato)silane, ethyl bis(ethyl lactato)silane, phenyl bis(ethyl lactato)silane, vinyl bis(ethyl lactato)silane, tri(ethyl lactato)silane, methyl bis(ethyl salicylato)silane, ethyl bis(ethyl salicylato)silane, phenyl bis(ethyl salicylato)silane, vinyl bis(ethyl salicylato)silane, tri(ethyl salicylato)silane, methyl bis(diethyl malato)silane, ethyl bis(diethyl malato)silane, phenyl bis(diethyl malato)silane, vinyl bis(diethyl malato)silane, tri(diethyl malato)silane and mixtures thereof.

11. The curable composition according to claim 6, wherein the sum of n+m is a maximum of 2; and each R.sup.3 independently of one another stands for a group of the formula (3), wherein Y is a substituted or unsubstituted aromatic group having 6 carbon ring atoms or C(R.sup.5).sub.2).sub.o, wherein o is 1 and one of the R.sup.5 groups is hydrogen and the second R.sup.5 group is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, R.sup.6 represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and R.sup.7 represents a group of the formula (4), where R.sup.8 is a C1-10 alkylene group, each R.sup.9 independently of one another stands for a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and each R.sup.19 independently of one another stands for a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms; and p is 0 or 1.

12. The curable composition according to claim 1, wherein the curing catalyst is a tin compound selected from 1,3-dicarbonyl compounds of bivalent or tetravalent tin, dialyltin(IV) dicarboxylates, dialkyltin(IV) dialkoxylates, dialkyltin(IV) oxides, tin(II) carboxylates, and mixtures thereof.

13. The curable composition according to claim 1, further comprising any one or more additional ingredients selected from the group consisting of plasticizers, fillers, bases, and adhesion promoters different from the capped adhesion promoter (B).

14. The curable composition according to claim 1, wherein the composition further comprises at least one adhesion promoter different from the capped adhesion promoter, wherein said additional adhesion promoter is selected from the group consisting of 3-(N,N-dimethylamino)propyltrimethoxysilane, 3-(N,N-dimethylamino)propyltriethoxysilane, (N,N-dimethylamino)methyltrimethoxysilane, (N,N-dimethylamino)methyltriethoxysilane, 3-(N,N-diethylamino)propyltrimethoxysilane, 3-(N,N-diethylamino)propyltriethoxysilane, (N,N-diethylamino)methyltrimethoxysilane, (N,N-diethylamino)methyltriethoxysilane, bis(3-trimethoxysilyl)propylamine, bis(3-triethoxysilyl)propylamine, 4-amino-3,3-dimethylbutyltrimethoxy silane and 4-amino-3,3-dimetylbuthyltriethoxy silane.

15. An adhesive, sealing, or coating material comprising the curable composition according to claim 1.

16. Cured reaction products of the curable composition according to claim 1.

17. An article comprising a surface and cured reaction products of the curable composition according to claim 1 bonded to the surface.

Description

EXAMPLES

Example 1

[0171] The comparison composition C1 and the compositions E1 and E2 according to the invention were prepared by mixing the raw materials listed in Table 1. The formulations differ in the type of the adhesion promoter used. The polyorganosiloxane (A) was obtained in a first step by combining the siloxane with the vinyl tris(ethyl lactato)silane.

TABLE-US-00001 TABLE 1 E1 E2 C1 C2 Parts by Parts by Parts by Parts by Raw materials weight weight weight weight ,-dihydroxy-terminated 52.18 52.18 52.71 52.58 polydimethylsiloxane with a viscosity of 80,000 cST Vinyl tris(ethyl lactato)silane 4.92 4.92 4.97 4.95 Plasticizer (,-dimethyl- 33.04 33.04 33.39 33.29 terminated Polydimethylsiloxane with a viscosity of 1,000 cST) Highly dispersed silicic acid 7.28 7.28 7.35 7.33 3-(N,N-dimethyl- 0.5 0.5 amino)propyltrimethoxysilane Capped amino silane A 2.01 2.01 Capped amino silane B 0.39 0.67 3-Aminopropyltrimethoxysilane 0.39 0.9 0.5 Tin compound (dioctyltin dilaurate 0.18 0.18 0.18 0.18 (DOTL))
Capped amino silane A is a compound of formula (I), wherein q is 0, R.sup.11 is propylene, each R.sup.13 is ethyl and B is a group of formula (1) wherein R.sup.15 and R.sup.16 are both Si(R.sup.17).sub.3 and each R.sup.17 is methyl.
Capped amino silane B is a ketimine that is similar to compounds of formula (I), wherein q is 0, R.sup.11 is propylene, each R.sup.13 is ethyl but B is NC(isobutyl)(methyl) (isobutylmethylimino).

[0172] Polymer (A) was formed from the ,-Dihydroxy-terminated polydimethylsiloxane and the vinyl tris(ethyl lactato)silane in a previous step and then combined with the adhesion promoters and the curing catalyst.

[0173] The prepared formulations were subjected to curing performance tests as follows:

[0174] Determination of Skin-over time (SOT): Skin-over time (SOT) is defined as the time required for the material to form a non-tacky surface film. The determination of the skin over time is carried out according to DIN 50014 under standard climate conditions (23+/2 C., relative humidity 50+/5%). The temperature of the sealant must be 23+/2 C., with the sealant stored for at least 24 h beforehand in the laboratory. The sealant is applied to a sheet of paper and spread out with a putty knife to form a skin (thickness about 2 mm, width about 7 cm). The stopwatch is started immediately. At intervals, the surface is touched lightly with the fingertip and the finger is pulled away, with sufficient pressure on the surface that an impression remains on the surface when the skin formation time is reached. The skin-over time is reached when sealing compound no longer adheres to the fingertip. The skin-over time (SOT) is expressed in minutes.

[0175] Measurement of Shore A hardness: Shore A hardness was measured according to ISO 868.

[0176] Determination of the depth of cure (DOC): A strip of the material with a height of 10 mm (+/1 mm) and width of 20 mm (+/2 mm) was applied over a plastic foil (PP) using a Teflon spatula. After storing the sample for 24 hours at normal conditions (23+/2 C., relative humidity 50+/5%), a section of the strip was cut off and the thickness of the cured layer was measured with a caliper. The depth of cure after 24 hours is expressed in millimeters.

[0177] Assessment of the mechanical properties (tensile test): The Tensile test determines the breaking force, elongation at break and yield stress value (e-module), according to DIN 53504. Deviation from the norm: dumbbell specimens with the following dimensions were used: thickness 2+/0.2 mm; bar width 10+/0.5 mm; bar length approx. 45 mm; total length 9 cm. The tests took place at normal conditions (23+/2 C., relative humidity 50+/5%). The measurement was carried out after 7 days of curing. Procedure: the prepolymer mixture (formulation) was spread on an even surface forming a film with a thickness of 2 mm. The film was allowed to cure under normal conditions (see above) for seven days, and then the dumbbell specimen was punched out. Three specimens were used for each determination. The test was carried out under normal conditions. The test specimens have to be at the same temperature at which the measurement will take place. Before the measurement, the thickness of the test specimens is determined at least at three different positions, at the middle and at the extremes, with a caliper. The mean value is introduced in the measuring software. The test specimens are clamped into the tensile tester so that the longitudinal axis coincides with the mechanical axis of the tensile tester and comprises the largest possible surface of the rod heads, without clamping the middle bar. Then the dumbbell is stretched to <0.1 MPa with a rate of 50 mm/min.. Then, the force-elongation curve is recorded with a line speed of 50 mm/min. Evaluation: The following values are determined: breaking force in [N/mm.sup.2] elongation at break in [%] and modulus at 100% elongation in [N/mm.sup.2].

[0178] Peel Test:

[0179] If possible and needed, substrate (test panel) is cleaned prior to application using a suitable solvent. A strip of the material with a height of 10 mm (+/1 mm) and width of 20 mm (+/2 mm) was applied over the substrate using a Teflon spatula. The sample was stored for 7 days at normal conditions (23+/2 C., relative humidity 50+/5%). The cured material was cut back for at least 15mm with a shape blade and the bead pulled by hand. Failure mode was recorded as following:

[0180] Cohesion failure (CF) or alternatively cohesive/adhesive failure

[0181] Adhesion failure (AF) with strong resistance

[0182] x Adhesion failure.

TABLE-US-00002 TABLE 2 Properties of compositions prior to storage (directly after mixing) E1 E2 C1 C2 SOT (min) 13 7 5 10 Shore A 1 d 12 12 12 12 Shore A 7 d 17 16 20 14 cure through 4.44 3.86 3.66 3.21 (mm in 24 h) tack 24 h Tack free Tack free Tack free Tack free ADHESION PMMA ~ x ~ ~ Aluminum/Elox Brass Glass ~ Concrete ~ ~ Modulus at 0.32 0.26 0.32 0.23 100% Elongation at 651.8 701.5 587.9 613.7 break

TABLE-US-00003 TABLE 3 Properties of compositions after storage (8 weeks; 40 C., 80% humidity) E1 C1 SOT (min) 24 24 Shore A 1 d 2 8 Shore A 7 d 17 cure through 3.36 4.02 (mm in 24 h) tack 24 h Tack free Tack free ADHESION PMMA ~ x Aluminum/Elox ~ Brass Glass Concrete ~ x Modulus at 0.2 0.33 100% Elongation at 678.4 583.5 break

[0183] The results show that the compositions of the invention have a better adhesion and significantly higher storage stability compared to the comparative composition.