SEALANT COMPOSITION

Abstract

Two-part condensation curable silyl-modified polymer (SMP) based sealant compositions, in particular two-part condensation curable SMP based translucent sealant compositions containing a catalyst comprising (i) a titanate and/or zirconate and (ii) a metal carboxylate salt.

Claims

1. A two-part condensation curable silyl modified polymer-based sealant composition comprising a base part, Part A, and a catalyst package, Part B, wherein the base part comprises: (a) a silyl modified organic polymer having at least two (R).sub.m(Y.sup.1).sub.3-m—Si— groups per molecule where each R is hydroxyl or a hydrolysable group, each Y.sup.1 is an alkyl group containing from 1 to 8 carbons and m is 1, 2 or 3, which organic polymer is selected from polyethers, hydrocarbon polymers, acrylate polymers, polyesters, polyurethanes and polyureas; and (b) a reinforcing filler; and optionally, further comprising: (c) is one or more plasticisers and/or (d) is-one or more stabilizers; and wherein the a catalyst package comprises: (ai) a silyl modified organic polymer having at least two (R).sub.m(Y.sup.1).sub.3-m—Si— groups per molecule where each R is hydroxyl or a hydrolysable group, each Y.sup.1 is an alkyl group containing from 1 to 8 carbons and m is 1, 2 or 3, which organic polymer is selected from polyethers, hydrocarbon polymers, acrylate polymers, polyesters, polyurethanes and polyureas; (e) a catalyst comprising (i) a titanate and/or zirconate and (ii) a metal carboxylate salt; and (f) an adhesion promoter; and optionally, further comprising: (g) a cross-linker; and/or (h) a hydroxy scavenging agent selected from a disilazane or polysilazane.

2. The two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1, wherein catalyst (e) is the metal carboxylate salt (ii) and the metal of the metal carboxylate salt (ii) is selected from the group consisting of zinc, aluminium, bismuth, zirconium, and combinations thereof.

3. The A-two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1 wherein catalyst (e) is the metal carboxylate salt (ii) and is selected from the group consisting of zinc (II) carboxylates, aluminium (III) carboxylates, bismuth (III) carboxylates, zirconium (IV) carboxylates, zinc (II) alkylcarboxylates, aluminium (III) alkylcarboxylates, bismuth (III) alkylcarboxylates, zirconium (IV) alkylcarboxylates, and combinations thereof.

4. The two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1, wherein catalyst (e) is the metal carboxylate salt (ii) and is selected from the group consisting of catalyst zinc ethylhexanoate, bismuth ethylhexanoate, zinc stearate, zinc undecylenate, zinc neodecanoate, and iron (III) 2-ethylhexanoate; and/or wherein the titanate and/or zirconate (i) and the metal carboxylate salt (ii) of catalyst (e) is provided in a molar ratio of 1:4 to 4:1.

5. The two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1, wherein silyl modified organic polymer (a) and/or silyl modified organic polymer (ai) is a polyether terminated with
(R).sub.m(Y.sup.1).sub.3-m—Si-D-[NH—C(═O)].sub.k— where each R is hydroxyl or a hydrolysable group, each Y.sup.1 is an alkyl group containing from 1 to 8 carbons, m is 1, 2 or 3, D is a divalent C.sub.2-6 alkylene group and k is 1 or 0.

6. The two-part condensation curable silyl modified polymer-based sealant composition in accordance claim 5, wherein k is 0.

7. The two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1 wherein Part A comprises: silyl modified organic polymer (a) in an amount of from 50 to 965 by weight of Part A; and reinforcing filler (b) in an amount of from 4 to 40% by weight of Part A; one or more plasticisers (c) in an amount of from 0 to 40% by weight of Part A; and one or more stabilizers (d) in an amount of from 0 to 5% by weight of Part A; wherein the total weight % of any Part A of the composition is 100%.

8. The two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1, wherein Part B comprises: silyl modified organic polymer (ai) in an amount of from 50 to 97.9% by weight of Part B; catalyst (e) in an amount of from 2 to 10% by weight of Part B; adhesion promoter (f) in an amount of from 0.1 to 25% by weight of Part B; cross-linker (g) in an amount of from 0 to 25% by weight of Part B; and moisture scavenger (h) in an amount of from 0 to 10% by weight of Part B; wherein the total weight % of any Part B of the composition is 100%.

9. The two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1, wherein Part A and Part B are inter-mixed in a weight ratio of from 15:1 to 1:1.

10. A method of making the two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1, the method comprising mixing all of Part A and Part B together in a pre-defined weight ratio of from 15:1 to 1:1.

11. An elastomeric sealant material which is the cured product of the two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1.

12. The elastomeric sealant material in accordance with claim 11, which is translucent.

13. A sealant suitable for use in the facade, insulated glass, window construction, automotive, solar and construction fields wherein the sealant comprises or is formed from the two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1.

14. A method for filling a space between two substrates so as to create a seal therebetween, the method comprising: a) providing the two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 1, and either b) or c); b) applying the silicone composition to a first substrate, and bringing a second substrate in contact with the sealant composition that has been applied to the first substrate, or c) filling a space formed by the arrangement of a first substrate and a second substrate with the sealant silicone composition and curing the sealant silicone composition.

15. The two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 7, wherein Part B comprises: silyl modified organic polymer (ai) in an amount of from 50 to 97.9% by weight of Part B; catalyst (e) in an amount of from 2 to 10% by weight of Part B; adhesion promoter (f) in an amount of from 0.1 to 25% by weight of Part B; cross-linker (g) in an amount of from 0 to 25% by weight of Part B; and moisture scavenger (h) in an amount of from 0 to 10% by weight of Part B; wherein the total weight % of any Part B of the composition is 100%.

16. The two-part condensation curable silyl modified polymer-based sealant composition in accordance with claim 15, wherein Part A and Part B are inter-mixed in a weight ratio of from 15:1 to 1:1.

Description

EXAMPLES

[0096] All viscosities mentioned were measured at 25° C. using a Brookfield® HAF viscometer using spindle No. 7 at 20 rpm. Dumbbell shaped Test pieces were used for all testing in accordance with ASTM D412-98a(2002e1).

[0097] A series of examples have been prepared and are compared with a two-part reference material. The formulation of Part A composition is depicted in Table 1 below.

TABLE-US-00001 TABLE 1 Part A composition of Examples (wt. %) Part A Composition Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Kaneka S303H SMP Polymer 74 74 74 74 74 Dow Voranol ™ 3003LM 15 15 15 15 15 Plasticizer Wacker HDK ® V15D Untreated 11 11 11 11 11 fumed Silica

[0098] Kaneka S303H SMP Polymer is a branched methyldimethoxysilane terminated polyether, without Urethane bond, viscosity 13,000 mPa.Math.s at 25° C. commercially available from Kaneka. Voranol™ 3003LM is a hydroxyl terminated Polypropylene ether from the Dow Chemical Co. and HDK® V15D is an untreated fumed silica, with BET 130-170 m.sup.2/g, commercially available from Wacker Chimie AG

[0099] The part A composition was prepared by adding the ingredients into a speed mixer and mixing 40 seconds at 2000 rpm at approximately room temperature (23° C.) and 50% relative humidity (RH) and then was stored.

[0100] The formulation of the catalyst package (Part B) composition is depicted in Tables 2a and 2b below:

TABLE-US-00002 TABLE 2a catalyst package (Part B) composition of Examples Part B Composition Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 methyltrimethoxysilane 4 4 4 4 4 Adhesion Promoter 5.8 5.8 5.8 5.8 5.8 Kaneka SAX520 79.2 79.2 79.2 79.2 79.2 Evonik Aerosil ® R208 3 3 3 3 3 Catalyst (See below) 8 8 8 8 8

[0101] Kaneka SAX520 is a branched trimethoxysilane terminated polyether, without Urethane bond, viscosity 52,000 mPa.Math.s at 25° C. Aerosil® R208 is a silicone oil-treated fumed silica, with BET 80-140 m.sup.2/g, from EVONIK. The adhesion promoter used was the reaction product of a mixture of Trimethoxymethylsilane, 3-aminopropyl trimethoxysilane, and glycidoxypropyl trimethoxysilane.

[0102] The catalysts used in the composition depicted in Table 2a are listed in the following Table 2b.

TABLE-US-00003 TABLE 2b Description of Catalysts in Examples 1 to 5 Catalyst Ex. 1 Tetra t-butyl titanate (TtBT) + zinc Ethylhexanoate (Zn(EHA).sub.2) (2:1 mol) premix Ex. 2 TtBT + Zn(EHA).sub.2 (2:1 mol) separately adding Ex. 3 TtBT + Zn(EHA).sub.2 (4:1 mol) Ex. 4 TtBT + Zn(EHA).sub.2 (1:4 mol) Ex. 5 TtBT + bismuth ethylhexanoate (Bi(EHA).sub.3) (2:1 mol)

[0103] The catalyst package (part B) composition was also prepared by adding the ingredients into a speed mixer and mixing 40 seconds at 2000 rpm at approximately room temperature (23° C.) and 50% relative humidity (RH) and then was stored.

[0104] In order to effect cure of the total composition Parts A and B were mixed together in a weight ratio of Part A:Part B of 3:1. The combined amounts were added into a speed mixer and mixed again for 40 seconds at 2000rpm at approximately room temperature (23° C.) and 50% relative humidity (RH). The resulting prepared compositions were cured for 7 days at room temperature (approximately 23° C. and 50% RH) and then had physical properties analysed.

[0105] Snap time is measured by gently touching at regular time intervals (typically 2-3 min) a spatula into 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.

TABLE-US-00004 TABLE 3 Physical Properties of Examples 1 to 5 Properties Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Snap Time (h) 4 4 5 <24 24 Tensile Strength (MPa) 1.65 1.62 2.22 2.11 0.97 (ASTM D412-98a(2002e1)) (7d RT cure) Elongation (%) (ASTM 223 227 284 318 271 D412-98a (2002e1)) (7d RT cure) Modulus @ 100% Extension 0.77 0.76 0.78 0.63 0.37 (MPa)) (ASTM D412-98a (2002e1)) (7d RT cure)

[0106] A series of comparative composition were also prepared. The part A compositions for these were identical to those in the above.

TABLE-US-00005 TABLE 4 Part A composition of Comparatives Part A Comp. 1 Comp. 2 Comp. 3 Comp. 4 Kaneka S303H SMP 74 74 74 74 Polymer Dow Voranol ™ 3003LM 15 15 15 15 Plasticizer Wacker HDK ® V15D 11 11 11 11 Untreated fumed Silica

[0107] The catalyst packages of the comparatives are disclosed in Table 5 below:

TABLE-US-00006 TABLE 5 Catalyst Package (Part B) composition of Comparatives Part B Comp. 1 Comp. 2 Comp. 3 Comp. 4 methyltrimethoxysilane 4 4 4 4 Adhesion Promoter 5.8 5.8 5.8 5.8 Kaneka SAX520 82.3 79.2 84.1 79.2 Evonik Aerosil ® R208 3 3 3 3 TtBT 4.9 8 Zn(EHA).sub.2 3.1 Bi(EHA).sub.3 8

[0108] Some physical properties of the comparative compositions were tested and are provided in Table. 6 below:

TABLE-US-00007 TABLE 6 Physical Property results of Comparatives Properties Comp. 1 Comp. 2 Comp. 3 Comp. 4 Snap Time (h) >24 24 uncured uncured Tensile Strength (MPa)) 0.19 2.36 uncured uncured (ASTM D412-98a(2002el)) (7d RT cure) Elongation (%)) (ASTM 166 340 uncured uncured D412-98a(2002e1)) (7d RT cure) Modulus @ 100% Extension 0.17 0.67 uncured uncured (MPa)) (ASTM D412-98a (2002e1)) (7d RT cure)

[0109] It will be observed that the catalyst (e), particularly when consisting of a titanate and a zinc carboxylate combination gives a much faster cure than using only the equivalent amount of the titanate catalyst alone as seen in ex. 1 and comp. 1. Comp. 3 is provided to show that the Zn(EHA).sub.2 when used on its own as catalyst showed very limited catalytic effect, its combination with the titanate clearly demonstrates an unexpected synergistic effect, again when comparing ex. 1 to comp. 1 and 3.

[0110] Whilst very high levels of titanate can be seen to cure two-part compositions described above (comp. 2), the cure is much slower than when using the catalyst (e) herein, snap tome of 24 hours and furthermore provides the added disadvantage of the likelihood of increasing discolouration (whitening and/or yellowing when utilised at such levels a, feature that users of translucent sealants seek to avoid, and consider a major issue. One advantage of utilizing the synergistic effect seen using the catalyst combination herein is that the need for levels of titanate catalyst means a much lower risk of discolouration with time.