MOISTURE CURABLE COMPOSITIONS

Abstract

Disclosed is a two-component silicone composition, which can cure via two part moisture cure organosiloxanc composition. The composition generally has which could improved cure speed while whilst maintaining good storage stability.

Claims

1. A two-component moisture curing silicone composition having a base component and catalyst package component wherein the catalyst package component comprises: (i) an (R.sup.4O).sub.m(Y.sup.1).sub.3-mSi-terminated organic polymer, where R.sup.4 is a C.sub.1-10-alkyl group, Y.sup.1 is a C.sub.1-8-alkyl group, and m is 1, 2 or 3, and where the organic polymer is selected from the group consisting of polyethers, hydrocarbon polymers, acrylate polymers, polyurethanes, and polyureas; (ii) at least one dipodal silane with the general formula:
(R.sup.4O).sub.m(Y.sup.1).sub.3-mSi(CH.sub.2).sub.x(NHCH.sub.2CH.sub.2).sub.t-Q(CH.sub.2).sub.xSi(OR.sup.4).sub.m(Y.sup.1).sub.3-m, where each R.sup.4 is independently a C.sub.1-10-alkyl group, each Y.sup.1 is independently a C.sub.1-8 alkyl group, Q is a heteroatom containing moiety with a lone pair of electrons, each x is independently an integer of from 1 to 6, t is 0 or 1, and each m is independently 1, 2 or 3; (iii) a non-dipodal adhesion promoter; (iv) a tin based catalyst; and optionally (v) a cross-linker.

2. The two component moisture curing silicone composition in accordance with claim 1, wherein the base component comprises: (a) a siloxane polymer having at least two terminal hydroxyl or hydrolysable groups and a viscosity of from 1000 to 200,000 mPa.Math.s at 25 C.; (b) at least one reinforcing fillers; and optionally (c) at least one non-reinforcing fillers.

3. (canceled)

4. The two part moisture curing composition in accordance with claim 1, wherein the dipodal silanes (ii) are is selected from the group consisting of bis (trialkoxysilylalkyl) amines, bis (dialkoxyalkylsilylalkyl) amines, bis (trialkoxysilylalkyl) N-alkylamines, bis (dialkoxyalkylsilylalkyl) N-alkylamine, and bis (trialkoxysilylalkyl) ureas, bis (dialkoxyalkylsilylalkyl) ureas, and combinations thereof.

5. The two part moisture curing composition in accordance with claim 1, wherein the dipodal silanes (ii) is selected from the group consisting of bis (3-trimethoxysilylpropyl) amine, bis (3-triethoxysilylpropyl) amine, bis (4-trimethoxysilylbutyl) amine, bis (4-triethoxysilylbutyl) amine, bis (3-trimethoxysilylpropyl) N-methylamine, bis (3-triethoxysilylpropyl) N-methylamine, bis (4-trimethoxysilylbutyl) N-methylamine, bis (4-triethoxysilylbutyl) N-methylamine, bis (3-trimethoxysilylpropyl) urea, bis (3-triethoxysilylpropyl) urea, bis (4-trimethoxysilylbutyl) urea, bis (4-triethoxysilylbutyl) urea, bis (3-dimethoxymethylsilylpropyl) amine, bis (3-diethoxymethyl silylpropyl) amine, bis (4-dimethoxymethylsilylbutyl) amine, bis (4-diethoxymethyl silylbutyl) amine, bis (3-dimethoxymethylsilylpropyl) N-methylamine, bis (3-diethoxymethyl silylpropyl) N-methylamine, bis (4-dimethoxymethylsilylbutyl) N-methylamine, bis (4-diethoxymethyl silylbutyl) N-methylamine, bis (3-dimethoxymethylsilylpropyl) urea, bis (3-diethoxymethyl silylpropyl) urea, bis (4-dimethoxymethylsilylbutyl) urea, bis (4-diethoxymethyl silylbutyl) urea, bis (3-dimethoxyethylsilylpropyl) amine, bis (3-diethoxyethyl silylpropyl) amine, bis (4-dimethoxyethylsilylbutyl) amine, bis (4-diethoxyethyl silylbutyl) amine, bis (3-dimethoxyethylsilylpropyl) N-methylamine, bis (3-diethoxyethyl silylpropyl) N-methylamine, bis (4-dimethoxyethylsilylbutyl) N-methylamine, bis (4-diethoxyethyl silylbutyl) N-methylamine, bis (3-dimethoxyethylsilylpropyl) urea bis (3-diethoxyethyl silylpropyl) urea, bis (4-dimethoxyethylsilylbutyl) urea, bis (4-diethoxyethyl silylbutyl) urea, and combinations thereof.

6. The two part moisture curing composition in accordance with claim 1, wherein the dipodal silanes (ii) has the general formula:
(R.sup.4O).sub.3Si(CH.sub.2).sub.x(NHCH.sub.2CH.sub.2).sub.tNH(CH.sub.2).sub.xSi(OR.sup.4).sub.3, where each of R.sup.4, x, and t is as defined above.

7. The two part moisture curing composition in accordance with claim 1, wherein the dipodal silanes (ii) is selected from the group consisting of bis (3-tripropyloxysilypropyl) amine, bis (3-methyldiethoxysilypropyl) amine, bis (3-methyldimethoxysilypropyl) amine, bis (3-triethoxysilylpropyl) amine, bis (3-trimethoxysilylpropyl) amine N,N-bis [3-trimethoxysilyl) propyl] ethylenediamine and combinations thereof.

8. The two part moisture curing composition in accordance with claim 2, wherein the siloxane polymer (a) is present in the composition in an amount of from 10 to 90 weight % based on the total weight of the base component.

9. The two part moisture curing composition in accordance with claim 2 wherein the reinforcing filler (b) is selected from the group consisting of fumed silicas, precipitated silicas, precipitated calcium carbonate, and combinations thereof.

10. The two part moisture curing composition in accordance with claim 1, wherein the weight ratio of the base component to the catalyst package component, when mixed, is between 15:1 and 1:1.

11. A one-part moisture curing composition comprising a mixture of the base component and the catalyst package component in accordance with the two-part moisture curing composition of claim 1.

12. The two part moisture curing composition in accordance with claim 2, wherein the base component comprises: 10 to 90 weight % of the siloxane polymer (a); 10 to 80 weight % of the reinforcing fillers (b); and 0 to 20 weight % of the non-reinforcing fillers (c); with the total weight % of the base component being 100 weight %.

13. The two part moisture curing composition in accordance with claim 1, wherein the catalyst package component comprises: 30 to 80 weight % of the terminated organic polymer (i); 5 to 50 weight % of the dipodal silanes (ii); 5 to 25 weight % of the non-dipodal adhesion promoter (iii); 0.01 to 3 weight % of the tin based catalyst (iv); and 0 to 25 weight % of the cross-linker (v); with the total weight % of the catalyst package component being 100 weight %.

14. An article comprising a composition or a reaction product thereof, wherein the composition is the two-part moisture curing composition in accordance with claim 1.

15. The article in accordance with claim 14, wherein the composition or reaction product thereof is further defined as a material selected from the group consisting of coating materials, caulking materials, mold making materials, encapsulating materials, and combinations thereof.

Description

EXAMPLES

Example 1

[0097] The intention herein was to provide a condensation cure adhesive/sealant for LED lamp substrates as an alternative to hydrosilylation cured materials to improve the strength of adhesion between substrates. Two part condensation cure adhesives/sealants provide fast deep section cure (over 90% of strength over 24 hours) and have a typical snap time of between 20-120 min), good adhesion to most substrates. They have the added advantage that the tin catalysts used to cure such compositions are not inactivated by other chemicals containing e.g. sulphur, and phosphorus. In order to be suitable for LED lighting applications it was needed to significantly reduce the snap time to between 3-6 min, and adhesion and strength build up need to be quick enough within 30 min.

[0098] The catalyst package composition is provided in Table 1a. Two base compositions were utilised for the present examples, identified as base (1) and Base (2) in Table 1b. In respect to this example base (1) was utilised.

TABLE-US-00001 TABLE 1a Catalyst Package Comp. 1 (wt. %) Trimethoxysilylethylene terminated 52.5 polydimethylsiloxane, viscosity = 30,000 mPa .Math. s @ 25 C. 2,2,4,4,6,6-Hexamethylcyclotrisilazane 0.5 Treated Fumed silica 3.50 1,6-Bis (trimethoxysilyl)hexane 20 aminopropyltriethoxysilane 16 bis (3-trimethoxysilypropyl)amine 7 Dimethyl TIN Dineodecanoate 0.275

TABLE-US-00002 TABLE 1b Base 1 Base 2 Base Component (wt. %) (wt. %) Treated precipitated calcium 49.5 50 carbonate Hydroxydimethyl terminated 50.5 50 polydimethylsiloxane viscosity of 4000 mPa .Math. s @ 25 C.

[0099] The viscosity over time of the catalyst package was determined using a Brookfield cone plate viscometer (RV DM) using cone plate CP-41 at 1 rpm and 5 rpm. Measurements were taken at 25 C. unless otherwise indicated. Results noted over time for samples aged at room temperature are provided in Table 1c and results noted over time after aging at a temperature of 50 C. are provided in Table 1d.

TABLE-US-00003 TABLE 1c 3 Month 5 Month aging at aging at Fresh Room temp. Room temp. Appearance OK OK Begin to crack after 4 Month storage viscosity (mPa .Math. s) 14150 6779 4617 using cone plate CP-41 at 1 rpm for 3 minutes viscosity (mPa .Math. s) 8802 3390 1611 using cone plate CP-41 at 1 rpm for 3 minutes

TABLE-US-00004 TABLE 1d 2 weeks 4 weeks 6 weeks 8 weeks aging at aging at aging at aging at Fresh 50 C. 50 C. 50 C. 50 C. Viscosity 14150 8449 5796 4814 5207 (mPa .Math. s) using cone plate CP-41 at 1 rpm for 3 minutes Viscosity 8802 3910 2299 1709 1709 (mPa .Math. s) using cone plate CP-41 at 1 rpm for 3 minutes
Snap time

[0100] After each time period identified in Table 1d the catalyst package analysed was mixed with the base (1) of Table 1b above and the snap time was determined and values are provided in Table 1e below.

[0101] Snap time is measured by gently touching at regular time intervals (typically 2-3 min) a spatula on the surface of the curing composition. As the cure progresses, the coating gains viscosity and elasticity. When these two are sufficiently high, the coating snaps off the spatula. The time elapsed between the casting of the coating and the first observation of the snap-off effect is recorded as snap time. This value has practical importance, because it provides an indication about the working time of the coating. The working time is defined as the time which the applicator is able to work with the material before the latter reaches a state of sufficiently high viscosity which prevents it from being properly handled and tooled. Snap time is used as a rough estimation of the working time. In this case base 2 was mixed with the catalyst package for the measurement of snap time.

TABLE-US-00005 TABLE 1e 2 weeks 4 weeks 6 weeks 8 weeks aging at aging at aging at aging at Fresh 50 C. 50 C. 50 C. 50 C. snap time 5.5 7.08 7.17 6.83 6.5 (min)

[0102] It was identified in Example 1 that whilst the addition of higher levels of primary amino silane and bis (3-trimethoxysilylpropyl)amine adhesion promoters certainly enhanced snap times, they met other complications in that the high levels of adhesion promoter used lead to destabilizing of the siloxane polymer carrier in the catalyst package leading to a significant reduction of viscosity of the catalyst package, i.e. poor storage stability.

Example 2

[0103] In this example the stability of two catalyst packages Ex.1 and Ex.2 as hereinbefore described are compared with those of a prior art unreactive silicone carrier material accordance with the invention. The composition of the catalyst packages used are provided in Table 2a. Polyether (1) was a trimethoxysilyl-terminated polyether having a viscosity of between 32000 and 45000 mPa.Math.s at 25 C. and polyether (2) was trimethoxysilyl-terminated polyether having a viscosity of approximately 120,000 mPa.Math.s at 25 C.

TABLE-US-00006 TABLE 2a Ex. 1 Ex. 2 Comp. 2 (wt. %) (wt. %) (wt. %) Polyether (1) 60.70 Polyether (2) 60.7 Trimethyl terminated polydimethyl- 60.70 siloxane 60,000 mPa .Math. s @ 25 C. 2,2,4,4,6,6-Hexamethylcyclotrisilazane 0.5 0.5 0.50 Treated Fumed silica 3.5 3.5 3.50 1,6-Bis (trimethoxysilyl)hexane 14 14 14.00 aminopropyltriethoxysilane 16 16 16.00 bis (3-trimethoxysilypropyl)amine 5 5 5.00 Dimethyl TIN Dineodecanoate 0.3 0.3 0.30 100.00 100.00 100.00

[0104] The viscosity over time of the catalyst package was determined, unless otherwise indicated) using a Brookfield cone plate viscometer (RV Dill) using cone plate CP-41 at 5 rpm. Measurements were taken at 25 C. unless otherwise indicated. Results noted over time for samples aged at room temperature and results noted over time after aging at a temperature of 50 C. are provided in Table 2b.

TABLE-US-00007 TABLE 2b Viscosity Viscosity Viscosity Ex. 1 Ex. 2 Comp. 3 (mPa .Math. s) (mPa .Math. s) (mPa .Math. s) Fresh at Room 6838 4853 36742 temperature (RT) (measured at 1 rpm as the viscosity will be out of the measurement range if measure at 5 rpm) Aging for 1 6857 4460 17349 week at RT Aging for 1 7132 4696 11258 month at RT Aging for 1 6562 4558 6464 week at 50 C. Aging for 2 6091 4774 6307 weeks at 50 C. Aging for 4 6012 4657 2731 weeks at 50 C.

[0105] It will be appreciated that the compositions using polyethers (1) and (2) carrier material in the catalyst package retained a reasonably constant measurements for viscosity over time after both room temperature and high temperature aging. Given these results weight average molecular weight values were determined for the polyethers and siloxane in the compositions as different polymer carriers using gel permeation chromatography. The results are depicted in Table 2c

TABLE-US-00008 TABLE 2c Ex. 1 Ex. 2 Comp. 3 Mw Mw Mw Fresh 35093 26292 107164 Aging for 1 29980 23548 82176 month at RT Aging for 1 33967 26660 67179 week at 50 C. Aging for 2 26918 21606 47704 weeks at 50 C. Aging for 4 27390 23239 36546 weeks at 50 C.

[0106] These results supported the results in Table 2b, i.e. that whilst the polyether based polymers were retaining their weight average Molecular weight during aging the siloxane was degrading resulting in a significant decrease in viscosity which showed a lack of stability of the catalyst package.

Example 3

[0107] In this study it is intended to determine the effect of high levels of catalyst in the absence of the dipodal silane (ii) and also the presence of the dipodal silane (ii) had an effect on snap time. The compositions used for the assessment are provided in Table 3a and the results attained are provided in Table 3b.

TABLE-US-00009 TABLE 3a Comp. 4 Ex. 3 Comp. 5 Comp. 6 Polyether (1) 66.7 59.7 64 54 Treated fumed silica 3 3 3 3 Bis 14 14 14 14 (trimethoxysilyl)hexane aminopropyl- 16 16 16 16 triethoxysilane Bis (3-trimethoxy- 0 7 0 0 silylpropyl)amine Dimethyl tin 0.3 0.3 3 13 dineodecanoate Total 100.00 100.00 100.00 100.00

[0108] In the following Table the adhesion to substrate surfaces was assessed by determining the lap shear tensile strength and the failure type (Adhesive/cohesive) as discussed below.

[0109] Lap shear Tensile Strength The base component and catalyst package were mixed and Samples of a pre-determined amount of the composition were applied onto a pre-cleaned first substrate surface in a laminating apparatus. A second substrate was the placed on top of the composition applied to the first substrate to give a pre-sized lap. The two substrates were compressed and excess composition was removed. The samples were cured at a temperature of 80 C. for a period of 30 minutes after which the lap shear tensile strength was determined by pulling apart by shear rather than peel (180 pull) at a rate of 5.1 cm/min.

Adhesive/Cohesive Failure

[0110] Adhesive failure (AF) refers to the situation when a sample detaches cleanly (peels off) from a substrate surface. Cohesive failure (CF) is observed when the coating itself breaks without detaching form the substrate surface. In most cases cohesive failure was observed on the previously pulled apart laminates. In some cases a mixed failure mode has been observed: i.e. some areas peel-off (i.e. AF) while some remain covered with coating (i.e. CF). In such instances the portion displaying CF (%C F) is recorded (bearing in mind % CF+% AF=100%). In this example the catalyst package was mixed with base 1.

TABLE-US-00010 TABLE 3b Comp. 4 Ex. 3 Comp. 5 Comp. 6 Snap time (min) 23.5 3.75 7.00 5.00 Viscosity Fresh 14481 8115 17899 10060 Viscosity, after 2 weeks 11455 5934 9156 6661 aging at 50 C. Lap shear tensile 887 907 1147 1103 strength (Adhesion build-up at Glass/Glass, interface) (kPa) Cohesive Failure on 100 100 100 100 glass (%) Lap shear Tensile 730 747 860 1215 Strength (Adhesion build- up at Glass/PBT interface) (KPa) Cohesive Failure on 95 100 100 100 glass (%) Cohesive Failure on 95 75 60 100 PBT (%) Lap Shear Tensile 975 1183 1265 1360 Strength (Adhesion build-up at Glass/ Aluminium interface), (KPa) Cohesive Failure on 100 100 100 100 glass (%) Cohesive Failure on 100 100 100 100 aluminium (%)

[0111] For the avoidance of doubt PBT is polybutylene terephthalate. The adhesion test with PBT gave apparently low results but these are standard for untreated PBT and the experiment was not repeated on activated PBT.

[0112] It was seen that in the absence of dipodal silane (ii) the snap time was significantly slower than required. It was also to be noted that compositions containing high levels of catalyst cause a significant reduction in polymer viscosity i.e. catalyst package stability.

Example 4

[0113] This example sought to determine whether or not the compositions would cure without the tin based catalyst (iii). The compositions used is depicted in Table 4a.

TABLE-US-00011 TABLE 4a Comp. 7 Comp. 8 Comp. 9 Comp. 10 polyether (1) 64 60 57 52 Treated fumed silica 3 3 3 3 Bis 14 14 14 14 (trimethoxysilyl)hexane aminopropyltriethoxy- 16 16 16 16 silane Bis (3-trimethoxy- 3 7 10 15 silylpropyl)amine Dimethyl tin 0 0 0 0 dineodecanoate Total 100.00 100.00 100.00 100.00

[0114] To generate snap time results etc., the catalyst package was mixed with base 1.

TABLE-US-00012 TABLE 4b Comp. 7 Comp. 8 Comp. 9 Comp. 10 Snap time (hours) >3.5 >3.5 >3.5 3 Viscosity Fresh 10394 7388 5423 3537 (mPa .Math. s) Viscosity, after 2 9274 6798 5108 3136 weeks aging at 50 C. (mPa .Math. s) Lap shear Tensile 30 26 25 20 Strength (Adhesion build-up at Glass/Glass interface) (KPa) Cohesive Failure on Did not Did not Did not Did not glass (%) Cure Cure Cure Cure

[0115] It was identified that the tin catalyst, (iii) was clearly an essential ingredient of the composition.

Example 5

[0116] Catalyst packages were prepared using a selection of alternative alkoxy silyl terminated organic polymers (i) with the compositions of the catalyst package being provided in Table 5a below wherein the alkoxy silyl terminated organic polymers (i) were as follows:

[0117] The acrylate polymer was a trimethoxysilyl-terminated polyacrylate having a viscosity of between about 70 Pas at 25 C. (E-type viscometer) and a glass temperature of about 50 C.;

[0118] Aliphatic polymer (1) was an alkoxysilyl terminated aliphatic prepolymer with a viscosity of approximately 20,000 mPa.Math.s at 23 C. (method M014-ISO 3219/A.3).

[0119] liphatic polymer (2) was an alkoxysilyl terminated aliphatic prepolymer with a viscosity of approximately 30,000-50,000 mPa.Math.s at 23 C. (method M014-ISO 3219/A.3).

[0120] In this case base 1 was mixed with the catalyst package.

TABLE-US-00013 TABLE 5a Ex. 4 Ex. 5 Ex 6 Ex. 7 Polyether (1) 59.65 Acrylate polymer 52.7 Aliphatic Polymer (1) 56.7 Aliphatic Polymer (2) 56.7 Treated fumed silica 3 10 6 6 Bis (trimethoxysilyl)hexane 14 14 14 14 aminopropyltriethoxy silane 16 16 16 16 Bis (3- 7 7 7 7 trimethoxysilylpropyl)amine Dimethyl tin dineodecanoate 0.35 0.3 0.3 0.30 Total 100.00 100.00 100.0 100.00

TABLE-US-00014 TABLE 5b Ex. 4 Ex. 5 Ex 6 Ex. 7 Snap time (min) 5.5 4.58 4.67 5.58 Compatibility good good, good good yellowing Lap Shear Tensile 953 760 600 810 Strength (Adhesion build-up at Glass/Glass interface) (KPa) Cohesive Failure on 100 100 100 100 glass (%)

TABLE-US-00015 TABLE 5c Viscosity Viscosity Viscosity Viscosity Ex. 4 Ex. 5 Ex. 6 Ex. 7 (mPa .Math. s) (mPa .Math. s) (mPa .Math. s) (mPa .Math. s) Fresh at Room 6798 33107 57372 50102 temperature (RT) Aging for 2 5894 43226 28883 25444 weeks at 50 C. Aging for 4 5875 32419 43520 28490 weeks at 50 C.