Moisture curable compositions

Abstract

Disclosed is a two-component silicone composition, which can cure via moisture. The composition generally has improved cure speed while 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) silicone organic copolymer having at least two hydroxy- or alkoxy groups per molecule, and comprising at least one organic polymer block selected from the group consisting of polyether, hydrocarbon, acrylate, polyurethane, and polyurea; (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.x—Si(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 200,000mPa.Math.s at 25° C.; (b) at least one reinforcing filler; and optionally (c) at least one non-reinforcing filler.

3. 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.

4. 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.

5. 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 filler (b); and 0 to 20 weight % of the non-reinforcing filler (c); with the total weight % of the base component being 100 weight %.

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

7. The two-part moisture curing composition in accordance with claim 1, wherein the dipodal silane (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.

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

9. The two-part moisture curing composition in accordance with claim 1, wherein the dipodal silane (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.

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 1, wherein the catalyst package component comprises: 30 to 80 weight % of the silicone organic copolymer (i); 5 to 50 weight % of the dipodal silane (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 %.

13. 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.

14. The article in accordance with claim 13, 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.

15. The two-part moisture curing composition in accordance with claim 1, wherein the silicone-organic copolymer (i) comprises an alternating copolymer, a block copolymer, or a rake-type copolymer.

Description

EXAMPLES

Example 1

(1) 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.

(2) 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.

(3) TABLE-US-00001 TABLE 1a Catalyst Package Comp. 1 (wt. %) Trimethoxysilylethylene terminated polydimethyl- 52.5 siloxane, 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

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

(5) The viscosity over time of the catalyst package was determined using a Brookfield® cone plate viscometer (RV DII) using cone plate CP-41 at either 1 rpm or 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.

(6) TABLE-US-00003 TABLE 1c 3 Month 5 Month aging at aging at Fresh Room temp. Room temp. Appearance OK OK Pates material stored in glass bottle showed some cracks after 4 Month of storage viscosity (mPa .Math. s) 14150 6779 4617 using cone plate CP-41 at 1 rpm viscosity (mPa .Math. s) 8802 3390 1611 using cone plate CP-41 at 5 rpm

(7) 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(mPa .Math. s) 14150 8449 5796 4814 5207 using cone plate CP-41 at 1 rpm for 3 minutes Viscosity(mPa .Math. s) 8802 3910 2299 1709 1709 using cone plate CP-41 at 5 rpm for 3 minutes
Snap Time

(8) 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.

(9) 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.

(10) 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)

(11) 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

(12) 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. The silicone polyether used was a rake type copolymer as hereinbefore described in the form of a trimethylsiloxy terminated dimethyl methyl polyether siloxane. The polyether side chain was an —OH terminated (propyl(poly(EO)(PO)) chain. The silicone polyether consisted of 18 weight % of siloxane groups, 35 weight % oxyethylene units and 46 weight % of oxypropylene groups and had a weight average molecular weight (Mw) of 27900 (GPC) and a viscosity at 25° C. of 2305 cSt determined by measuring the time required for a fixed volume of samples to pass through a calibrated glass capillary using “gravity-flow” based on ASTM D-445.

(13) TABLE-US-00006 TABLE 2a Ex. 1 Ex. 2 Comp. 2 (wt. %) (wt. %) (wt. %) Silicone polyether 59.2 57.7 Trimethyl terminated polydimethyl- 60.70 siloxane 60,000 mPa .Math. s @ 25° C. 2,2,4,4,6,6-Hexamethylcyclo- 0 1.5 0.50 trisilazane 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 7 7 5.00 Dimethyl TIN Dineodecanoate 0.3 0.3 0.30 100.00 100.00 100.00
Catalyst Package Preparation

(14) The catalyst package of Ex. 1 was prepared by mixing the silicone polyether and silica into a base formulation and then heating the resulting base formulation to approximately 110° C. under vacuum to remove moisture for approximately 1 hour. The resulting “anhydrous” base was then allowed to cool to about 30° C. and the remaining ingredients were introduced and thoroughly mixed.

(15) The catalyst package of Ex. 2 was prepared by first mixing the silicone polyether with the hexamethylcyclotrisilazane (used to react with moisture contained by the silicone polyether) followed by the silica to make a base formulation. The base formulation was then heated to approximately 110° C. under vacuum to remove moisture for approximately 1 hour. The resulting “anhydrous” base was then allowed to cool to about 30° C. and the remaining ingredients were introduced and thoroughly mixed.

(16) The viscosity over time of the catalyst package was determined, unless otherwise indicated) using a Brookfield® cone plate viscometer (RV DIII) 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.

(17) 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 temperature 1965 2201 36742 (RT) (measured at 1 rpm as the viscos- ity will be out of the measure- ment range if measure at 5 rpm) Aging for 1 week at RT 17349 Aging for 1 month at RT 11258 Aging for 4 month at RT 1120 963 Aging for 1 week at 50° C. 6464 Aging for 2 weeks at 50° C. 2220 884 6307 Aging for 4 weeks at 50° C. 2869 844 2731 Aging for 8 weeks at 50° C. 844 805

(18) It will be appreciated that the compositions using Ex. 1 and Ex. 2as the catalyst package retained 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 different polymer carriers using gel permeation chromatography. The results are depicted in Table 2c.

(19) TABLE-US-00008 TABLE 2c Ex. 1 Mw Ex. 2 Mw Comp. 3 Mw Fresh 29704 29808 107164 Aging for 1 month at RT 82176 Aging for 4 months at RT 29018 30383 Aging for 1 week at 50° C. 67179 Aging for 2 weeks at 50° C. 29221 29349 47704 Aging for 4 weeks at 50° C. 29257 30056 36546 Aging for 6 weeks at 50° C. 29037 29996 Aging for 8 weeks at 50° C. 29523 29439

(20) These results supported the results in Table 2b, i.e. that whilst Ex. 1 and Ex. 2 silicone polyether 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.

(21) 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.

(22) Lap Shear Tensile Strength

(23) The catalyst package was aged for 7 days at room temperature. The base component and catalyst package were then mixed in a 10:1 ratio 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.

(24) Adhesive/Cohesive Failure

(25) 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 (% CF) is recorded (bearing in mind % CF+% AF=100%). In this example the catalyst package was mixed with base 1.

(26) TABLE-US-00009 TABLE 3b Ex. 1 Ex. 2 Snap time (min) 3 3 Lap shear tensile strength (Adhesion build-up 1053 688 at Glass/Glass, interface) (kPa) Cohesive Failure on glass (%) 77 87 Lap shear Tensile Strength (Adhesion build-up 844 907 at Glass/PBT interface) (KPa) Cohesive Failure on glass (%) 100 90 Cohesive Failure on PBT (%) 10 27 Lap Shear Tensile Strength (Adhesion build-up 1674 1320 at Glass/Aluminium interface), (KPa) Cohesive Failure on glass (%) 100 83 Cohesive Failure on aluminium (%) 100 100

(27) 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.