Room temperature curable compositions

Abstract

A room temperature curable sealant/adhesive composition is disclosed. The room temperature curable sealant/adhesive composition comprises: (A) one or more organopolysiloxanes; (B) a hydrophilic material; (C) a cross-linker; (D) a titanate or zirconate catalyst; and (E) one or more optional ingredients. A silicone elastomer formed therefrom and related methods are also disclosed.

Claims

1. A silicone room temperature curable sealant/adhesive composition comprising: (A) at least 50% by weight of one or more organopolysiloxanes selected from: (i) (RO).sub.3-a(R).sub.aSiZ(Si(R).sub.2O).sub.XSi(R).sub.2ZSi(OR).sub.3-a(R).sub.a where each R is free of aliphatic unsaturation and is independently selected from the group consisting of monovalent hydrocarbon, monovalent halohydrocarbon, and monovalent cyanoalkyl radicals having from 1 to 18 carbon atoms, each R is independently a monovalent hydrocarbon group having 1 to 6 carbon atoms, Z is a divalent hydrocarbon radical or combination of divalent hydrocarbon radicals and siloxane radicals, a is 0 or 1, and x is of a value such that component (A)(i) has a viscosity of from 0.5 to 3000 Pas at 25 C.; (ii) alpha, omega-diorganopolysiloxane of the formula
(HO).sub.3-b(R).sub.bSiO(Si(R).sub.2O).sub.ySi(OH).sub.3-b(R).sub.b where each R is free of aliphatic unsaturation and is independently selected from the group consisting of monovalent hydrocarbon, monovalent halohydrocarbon, and monovalent cyanoalkyl radicals having from 1 to 18 carbon atoms, b is 0, 1 or 2, and y is of a value such that component (A)(ii) has a viscosity of from 0.5 to 3000 Pas at 25 C. and a number average molecular weight (M.sub.n) of from 1000 to 1000000; or (iii) mixtures of the above; (B) 5 to 35% by weight of a hydrophilic material comprising (B)(iii) polymers containing ionisable groups; (C) 0.5 to 7.5% by weight of a cross-linker selected from a silane or siloxane cross linker containing at least two alkoxy or alkenyloxy groups, or silyl functional molecules having at least two silyl groups, each silyl group containing at least one alkoxy or alkenyloxy group; (D) 0.5 to 5% by weight titanate or zirconate catalyst; and (E) optionally, one or more ingredients selected from fillers, co-catalysts, rheological modifiers, plasticisers, adhesion promoters, compatibilizers, pigments, heat stabilizers, flame retardants, UV stabilizers, chain extenders, electrically and/or heat conductive fillers, and/or fungicides/biocides; wherein the total % by weight of components (A)+(B)+(C)+(D)+(E) is 100%; and wherein the hydrophilic material is selected from homopolymers and copolymers comprising vinylsulphonic, styrenesulphonic, naphthalenesulphonic or acrylamidoalkylsulphonic units and their salts and also copolymers thereof with an unsaturated comonomer.

2. The silicone room temperature curable sealant/adhesive composition in accordance with claim 1, wherein component (B) is component (B)(iii).

3. The silicone room temperature curable sealant/adhesive composition in accordance with claim 1, stored before use in one or two parts.

4. The silicone room temperature curable sealant/adhesive composition in accordance with claim 1, which is a one-component composition which, when stored at a temperature above 30 C., prior to cure retains at least 50% of its mechanical strength upon cure.

5. A silicone elastomer resulting from curing the silicone room temperature curable sealant/adhesive composition in accordance with claim 1.

6. The silicone elastomer of claim 5, having a water pick up of at least 0.01 gram of water per gram of silicone elastomer, when the silicone elastomer is immersed in water or phosphate buffer saline for 24 h.

7. A sealant comprising the silicone elastomer in accordance with claim 5.

8. A method of controlling and/or restraining aqueous leaks, said method comprising disposing a silicone elastomer where joint expansion is desired, wherein the silicone elastomer is the silicone elastomer in accordance with claim 6.

9. A patch comprising the silicone elastomer in accordance with claim 5.

10. A method of filling a space defined between two substrates so as to form an arrangement, the method comprising: a) providing the silicone room temperature curable sealant/adhesive composition in accordance with claim 1; b1) applying the composition to a first substrate, and bringing a second substrate in contact with the composition that has been applied to the first substrate; or b2) filling a space defined by a first substrate and a second substrate with the composition; and c) curing the composition, thereby forming the arrangement.

11. The silicone room temperature curable sealant/adhesive composition in accordance with claim 1, wherein component (E) is present.

12. A medical device comprising the silicone elastomer in accordance with claim 5.

13. A diaper comprising the silicone elastomer in accordance with claim 5.

14. The silicone room temperature curable sealant/adhesive composition in accordance with claim 1, wherein component (B) comprises a mixture of component (B)(iii) and (B)(i) hydrophilic and/or water soluble resins based on polyethylene oxide and/or polypropylene oxide.

15. The silicone room temperature curable sealant/adhesive composition in accordance with claim 14, wherein component (B)(i) comprises polyoxyalkylene polymers comprising recurring oxyalkylene units illustrated by the average formula (C.sub.nH.sub.2nO).sub.y wherein n is an integer from two to four and y is an integer of at least four.

16. The silicone room temperature curable sealant/adhesive composition in accordance with claim 15, wherein the number average molecular weight of each polyoxyalkylene polymer is greater than 50000.

17. The silicone room temperature curable sealant/adhesive composition in accordance with claim 1, wherein component (B) comprises a mixture of component (B)(iii) and (B)(ii) one or more anionic surfactants.

18. The silicone room temperature curable sealant/adhesive composition in accordance with claim 17, wherein the one or more anionic surfactants (B)(ii) are selected from sodium/potassium sulphonates, alkenyl sulphonates, alkyl sulphates, alkyl-benzene sulphonates, potassium alkyl phosphates, alkyl succinates, alkyl sulphosuccinates and N-alkyl sarcosinates and sodium, magnesium, ammonium, and the mono-, di- and triethanolamine salts of alkyl and aralkyl sulphates as well as the salts of alkaryl sulphonates and/or mixtures thereof.

19. The silicone room temperature curable sealant/adhesive composition in accordance with claim 17, wherein component (B) comprises a mixture of components (B)(iii) and (B)(ii) and (B)(i) hydrophilic and/or water soluble resins based on polyethylene oxide and/or polypropylene oxide.

20. The silicone room temperature curable sealant/adhesive composition in accordance with claim 19, wherein: component (B)(i) comprises polyoxyalkylene polymers comprising recurring oxyalkylene units illustrated by the average formula (C.sub.nH.sub.2nO).sub.y wherein n is an integer from two to four and y is an integer of at least four; and the one or more anionic surfactants (B)(ii) are selected from sodium/potassium sulphonates, alkenyl sulphonates, alkyl sulphates, alkyl-benzene sulphonates, potassium alkyl phosphates, alkyl succinates, alkyl sulphosuccinates and N-alkyl sarcosinates and sodium, magnesium, ammonium, and the mono-, di- and triethanolamine salts of alkyl and aralkyl sulphates as well as the salts of alkaryl sulphonates and/or mixtures thereof.

Description

EXAMPLES

Definitions

(1) SOT=skin over time

(2) Skin Over Time (SOT) is the time required for a sealant/adhesive composition to cure to the point where it no longer adheres to a clean fingertip lightly touched on the surface thereof. Cure usually takes place at room temperature e.g. 22-25 C. and 25-35% relative humidity (RH).

(3) Cure in Depth (CID): The CID test consists of making a 1 cm thick specimen in a cup, allowing the moisture to penetrate only from the air/sealant interface. Samples are allowed to cure for predefined periods of time e.g. 1, 3 and/or 7 days, subsequent to which the thickness of the resulting cured layer is measured.

(4) WU=water uptake/absorbance

(5) Water absorbance have been tested using well-cured pre-weighed specimens. These were soaked in phosphate buffered saline (PBS). At pre-determined regular intervals the specimens were taken out of the PBS wiped to a dry state and weighed. Alternatively, water can be used instead of PBS.

(6) Formulation (all references to parts are intended to mean parts by weight)

(7) Three masterbatches were made for use in the Examples: Master batch type 1 was been prepared using 1.75 parts of 1,6-bis(trimethoxy silyl)hexane and 87 parts of trimethoxy silyl terminated siloxane polymer with viscosity of about 63000 mPa.Math.s at 25 C.; Masterbatch type 2 was prepared using 4 parts of cross linker and 87 parts of the same trimethoxy silyl terminated siloxane polymer; Masterbatch type 3 was prepared using 8 parts of cross-linker and 87 parts of the same trimethoxy silyl terminated siloxane polymer. The catalyst in all cases was tetra-n-butyl titanate.

(8) Sealants containing one of the above mentioned masterbatches; different amounts of water pick-up material and catalyst were formulated using a SpeedMixerDAC 150.1 FV-K. A 1-2 mm thick smear was immediately applied onto a glass surface to determine SOT.

(9) The rest of the sealant samples were then kept in open cylindrical containers (diameter approx. 4 cm, depth of the sample3 to 4 cm) for 7 days, exposed at the ambient atmosphere (approx. 50% RH) at 21-25 C. After that time, the skin formed on the top of the sealant is removed.

(10) If a cured layer (skin) of 0.5 to 1.5 cm depth has been formed, the composition is deemed to be a suitable one-component sealant (1K). The skin removed from the container is stored for another 24 h to 48 h on a lab bench to allow for complete cure (the side originally facing the bulk was exposed to the atmosphere). Thus obtained cured specimens were then used for evaluation of the water pick up ability of the formulations.

(11) The initial weight of each sample tested was between 2 and 6 grams, depending on the thickness.

(12) If bulk cure is observed (e.g. the entire sample has cured) the material is considered as suitable for a bi-component sealant (2K)

COMPARATIVE EXAMPLE

(13) The following comparative example is a standard formulation comprising masterbatch 1 and catalyst (i.e. no component B).

(14) TABLE-US-00001 Masterbatch Masterbatch Catalyst SOT Type type g g min of cure Comparative 1 1 35.64 0.36 20 1K

(15) TABLE-US-00002 Time when weight difference Measured (h) 0 22 72 96 Comparative 1 - weight difference (g) 0 0.008 0.007 0.01 (Initial weight 4.197 g)

(16) It will be seen that in the absence of component B of the composition the water take up even after 96 hours was negligible.

Example 1 Compositions Using Component B (i) Water Soluble Resin

Example 1a Composition

(17) In this Example component B in the formulation was of the type B) (i) a Hydrophilic and/or water soluble resin based on polyethylene oxide and/or polypropylene oxide. The resin used was a Polyox resin type WSR 205 which is commercially available from The Dow Chemical Company. Table 1 shows the composition of the sealants together with the type of cure and SOT.

(18) TABLE-US-00003 TABLE 1 Polyox Master- Catalyst WSR 205 Sample batch Masterbatch, amount amount SOT, Type of Number type amount (g) (g) (g) (min) cure 1p 1 35.64 0.36 4 50 1k 2p 1 35.28 0.72 4 30 1k 3p 1 34.92 1.08 4 35 1k 4p 1 34.56 1.44 4 30 1k 5p 1 34.2 1.8 4 15 1k 6p 1 31.68 0.32 8 45 1k 7p 1 31.36 0.64 8 24 1k 8p 1 31.04 0.96 8 20 1k 9p 1 30.72 1.28 8 10 1k 10p 1 30.4 1.6 8 10 1k 11p 1 29.255 0.25 10.5 50 1k 12p 1 29.01 0.49 10.5 45 1k 13p 1 28.765 0.74 10.5 20 1k 14p 1 28.52 0.98 10.5 17.5 1k 15p 1 28.275 1.23 10.5 15 1k 16p 3 34.56 1.44 4 120 1k 17p 3 30.4 1.6 8 45 1k

Example 1 bWater Pick Up

(19) A selection of the Samples made above were immersed in PBS and the increase of their weight (g) as a function of time is reported in Table 2.

(20) TABLE-US-00004 TABLE 2 Dry weight before Weight increase (g) sample immersion (g) 0 h 22 h 48 h 72 h 96 h 1p 4.197 0 0.201 0.256 0.282 0.320 3p 6.313 0 0.121 0.159 0.199 0.214 5p 5.863 0 0.091 0.148 0.175 0.208 6p 5.646 0 0.273 0.39 0.465 0.521 9p 7.69 0 0.245 0.355 0.441 0.514 10p 5.16 0 0.185 0.261 0.339 0.389 11p 5.064 0 0.351 0.498 0.601 0.689 13p 4.553 0 0.432 0.453 0.552 0.658 15p 2.764 0 0.281 0.44 0.536 0.638 11p 5.589 0 0.351 0.498 0.601 0.689 16p 3.108 0 0.106 0.132 0.157 0.185 17p 3.137 0 0.276 0.519 0.493 0.514

(21) One concludes that the inclusion of a water soluble resin in the compositions enables water to be adsorbed into the resulting cured elastomer as well as a having an SOT of less than 1 h. Surprisingly, although the resin is embedded within a hydrophobic matrix (silicone), the materials exhibit a substantial water pick up (table 2). Water uptake of the materials lead to the expansion on the testing specimens.

Example 1cStability

(22) Two formulations (9p and 14p) were subsequently prepared on a on a larger scale (330 g) and stored in standard sealant cartridges. One cartridge was kept at room temperature (RT=22-23 C.) and another at 40 C.+/2 C. for one week. The latter storage option is used to accelerate the aging of the material. Two mm thick sheets have been casted from the fresh and aged sealant and allowed to cure at RT (22-23 C.) at 50% relative humidity for 7 days. Test dumbbells have been cut and the mechanical properties of these specimens tested following ASTM D 412-06. It will be appreciated from the results in Table 3 that the mechanical properties upon ageing at 40 C. remain comparable within 25% to the initial values. The SOT does not exceed 70 min.

(23) TABLE-US-00005 TABLE 3 Formulation Formulation Formulation Formulation 9p 1 wk 14p -1 wk 9p- fresh 14p- fresh @ 40 C. @40 C. SOT (min) 31 15 65 43 CID 1 day (mm) 3.2 3.6 Dumbbells Tensile strength 0.61 1.03 0.51 0.77 7 Days cure (MPa) Elongation at 113 117 141 123 Break* (%) *also called ultimate elongation in ASTM 412 D - 06

Example 1dLarge Scale Preparation

(24) In a 5 L compounder 4000 g of the following sealant was prepared:

(25) TABLE-US-00006 Ingredient Wt % trimethoxy silyl terminated siloxane polymer with viscosity 33.6 of about 63000 mPa .Math. s at 25 C. 1,6-bis(trimethoxy silyl)hexane 1.6 Polyox WSR 205 30.4 Trimethyl siloxy-terminated polydimethyl siloxane with zero 33.6 shear viscosity of 3000 Pa .Math. s Tetra-n-butyltitanate (TNBT) 0.8

(26) The material was immediately packed in standard sealant cartridges (ca. 330 g per cartridge). 24 h after the packaging some of the cartridges were stored in an oven at 40 C, the rest were kept in room temperature (22-23 C.). 24 h after packaging the sealant was successfully extruded using a manual cartridge gun. After one week of storage in an oven at 40 C. the sealant was successfully extruded using a manual cartridge gun and no difference in appearance and extrudability was observed in comparison with the fresh sealant.

Example 2 Compositions Using Component B (ii) Anionic Surfactants

Example 2aComposition

(27) The methodology described in example 1a is used, but the water pick up component was an anionic surfactant B (ii). Following materials were used: Bioterge AS90 (commercial material from Stepan) sodium alpha-olefine sulphonate Hostapur SAS 93 G (commercial material from Clariant) Secondary alkane sulphonate, sodium salt.

(28) Nacconol 90 G (commercial material from Stepan) Sodium (C10-16) benzenesulphonate

(29) Dispolil SLS 128 (commercial materials from Cognis) Sodium lauryl sulphates (C12-C18)

(30) Table 4 shows the formulation, the type of cure and SOT. Table 5 shows the water pick up of selected formulations; stability data is shown in Table 6.

(31) TABLE-US-00007 TABLE 4 Anionic MB, Cata- Anionic Surfactant Type formu- MB Amount lyst amount surfactant SOT Of lation used (g) (g) used (g) (min) cure 1-as 1 23.76 0.24 Bioterge AS 6 50 2K 90 2-as 1 23.52 0.48 Bioterge AS 6 30 2K 90 3-as 1 23.28 0.72 Bioterge AS 6 15 1K 90 4-as 1 23.04 0.96 Bioterge AS 6 13 1K 90 5-as 1 22.8 1.2 Bioterge AS 6 10 1K 90 6-as 2 27.4 0.6 Bioterge AS 2.04 25-30 1k 90 7-as 3 27.42 0.6 Bioterge AS 2.04 1K 90 8-as 1 27.16 0.84 Hostapur 7 >240 1k SAS 93G 9-as 1 26.88 1.12 Hostapur 7 20 1k SAS 93G 10-as 1 26.6 1.4 Hostapur 7 18 1k SAS 93G 11-as 1 26.19 0.81 Hostapur 3 1k SAS 93G 12-as 1 25.65 1.35 Hostapur 3 1k SAS 3G 13-as 1 26.88 1.12 Nocconol 7 13-16 2k 90G 14-as 1 26.88 1.12 Disponil 7 15 1k SLS 128

Example 2bWater Pick-Up

(32) The methodology described in example 1b was repeated to evaluate the water pick up of some formulations containing anionic surfactants

(33) TABLE-US-00008 TABLE 5 Water pick-up in grams Dry weight before immersion, Weight increase upon immersion, (g) Formulation g 0 h 22-24 h 48 h 120 h 3-as 7.162 0 0.476 0.780 1.205 4-as 5.788 0 0.368 0.571 0.941 5-as 5.035 0 0.337 0.508 0.887 6-as 5.047 0 0.179 0.274 0.425 7-as 3.961 0 0.087 0.138 0.238 8- as 4.909 0 0.074 0.091 10-as 4.148 0 0.118 0.165 11-as 5.308 0 0.098 0.133 12-as 5.259 0 0.076 0.108

Example 2c Stability

(34) Following the methodology described in example 1c sample 10 as have been studied.

(35) TABLE-US-00009 TABLE 6 Formulation fresh- Formulation 10as 10as 1 wk @ 40 C. SOT (min) 41 63 CID 1 day (mm) 2.0 Dumbbells 7 Tensile strength 0.23 0.28 Days cure (MPa) Elongation at 72 175 Break* (%) *also called ultimate elongation in ASTM 412 D - 06

Example 3 Composition Containing Component B (iii) a Commercial Polymer with Pendant Sulphonic Groups and PVA

(36) Material used was Polyvinyl Alcohol (commercial name Mowiol 5-88) commercially available form KURARAY.

(37) Table 7 show the composition of the sealants made with PVA.

(38) TABLE-US-00010 TABLE 7A MB, MB, amount amount PVA, SOT, Type of Number MB used (g) (g) (g) (min) cure 1i 1 30.24 1.26 3.5 60+ 2k 2i 1 29.925 1.575 3.5 60+ 2k 3i 1 26.88 1.12 7 60+ 2k 4i 1 26.6 1.4 7 60+ 2k

(39) Table 7b water pick up material was sodium polystyrene sulphonate with MW of 75000 D, commercially available form Alfa Aesar

(40) TABLE-US-00011 TABLE 7B MB, MB, amount amount SOT, Type of Number MB used (g) (g) NaPSS (min) cure 5i 1 23.52 0.98 10.5 50 2k 6i 1 23.275 1.23 10.5 40-45 2k 7i 2 23.52 0.98 10.5 ~120 2k 8i 2 26.6 1.23 10.5 ~120 2k 9i 1 30.87 0.63 3.5 90 2k 10i 1 30.555 0.945 3.5 70 2k 11i 1 30.24 1.26 3.5 70 2k 12i 1 29.925 1.575 3.5 30 2k 13i 1 27.16 0.84 7.0 80-90 2k 14i 1 26.88 1.12 7.0 40-50 2k 15i 1 26.6 1.4 7.0 40 2k 16i 2 26.74 1.26 7.0 >120 2k 17i 2 26.42 1.575 7.0 >120 2k