Moisture curable compositions

Abstract

A two part moisture curing composition, exhibiting low thermal conductivity, has a part A) and a part B). Part A) comprises either: 1) a siloxane polymer (I) having at least two terminal hydroxyl or hydrolysable groups and a viscosity of from 20,000 to 40,000 mPa.Math.s at 25 C.; or 2) a polymer mixture (II) of polymer (i) a siloxane polymer having at least two terminal hydroxyl or hydrolysable groups and a viscosity25,000 mPa.Math.s at 25 C., and polymer (ii) a siloxane polymer having at least two terminal hydroxyl or hydrolysable groups and a viscosity of between 1,000 and 20,000 mPa.Math.s at 25 C. Part A) further comprises a reinforcing filler and a low-density filler, the total filler content being between 30 and 45% in volume of the total composition. Part B) comprises a moisture curing agent formulation comprising a tin based catalyst and one or more crosslinkers.

Claims

1. A two part moisture curing composition, said composition comprising: a part A); and a part B); wherein part A) comprises a polymer mixture of polymer (i) and polymer (ii), where polymer (i) is a siloxane polymer having at least two terminal hydroxyl or hydrolysable groups and a viscosity25,000 m.Math.Pas at 25 C., and where polymer (ii) is a siloxane polymer having at least two terminal hydroxyl or hydrolysable groups and a viscosity of between 1,000 and 20,000 m.Math.Pas at 25 C.; wherein part A) further comprises a reinforcing filler and a low-density filler; wherein the total filler content is between 30 and 45% in volume of the total composition; wherein part B) comprises a moisture curing agent formulation comprising; a tin based catalyst, and one or more crosslinkers having three or more hydroxyl and/or hydrolysable groups for curing part A); and wherein part A) and/or the composition of part A)+part B) after mixing has a thermal conductivity0.20 W/m.Math.K according to ISO 8301.

2. The two part moisture curing composition in accordance with claim 1, wherein polymer (i) is present in the composition in an amount of from 10 to 70% by weight based on the total weight of part A).

3. The two part moisture curing composition in accordance with claim 1, wherein polymer (ii) is present in the composition in an amount of from 10 to 70% by weight based on the total weight of part A).

4. The two part moisture curing composition in accordance with claim 1, wherein the reinforcing filler is selected from the group consisting of fumed silicas, precipitated silicas and/or precipitated or ground calcium carbonates, and is present in the composition in an amount of from 15 and 35% by weight of the total composition.

5. The two part moisture curing composition in accordance with claim 4, wherein the reinforcing filler comprises precipitated calcium carbonate.

6. The two part moisture curing composition in accordance with claim 1, wherein the low-density filler comprises mineral hollow microspheres having a particle density of between 0.15 to 0.5 g/cm.sup.3, and is present in the composition in an amount of from 3 to 35% by weight of the total composition.

7. The two part moisture curing composition in accordance with claim 6, wherein the low-density filler comprises hollow glass beads.

8. The two part moisture curing composition in accordance with claim 1, wherein the viscosity of the polymer mixture is between 20,000 and 40,000 mPa.Math.s at 25 C.

9. The two part moisture curing composition in accordance with claim 1, further comprising polymer (iii), a siloxane polymer having terminal hydroxyl or hydrolysable groups and a viscosity of between 10 and 500 mPa.Math.s at 25 C.

10. The two part moisture curing composition in accordance with claim 9, wherein polymer (iii) is present in an amount of from 0.5 to 10% by weight based on the total weight of part A).

11. The two part moisture curing composition in accordance with claim 1, wherein part A) comprises: 10 to 70 weight % of polymer (i); 10 to 70 weight % of polymer (ii); up to 10 weight % of polymer (iii), a siloxane polymer having terminal hydroxyl or hydrolysable groups and a viscosity of between 10 and 500 mPa.Math.s at 25 C.; 15 to 35 weight % of the reinforcing filler; and 3 to 35 weight % of the low-density filler, optionally hollow mineral microspheres; and optionally, one or more additives; with the total being 100 weight % of the part A) composition.

12. The two part moisture curing composition in accordance with claim 1, wherein the ratio of part A):part B) in the composition is between 15:1 and 1:1.

13. A one part moisture curing composition, said composition comprising a mixture of part A) and part B) in accordance with claim 1.

14. The one part moisture curing composition in accordance with claim 13, comprising: 30 to 70 weight % of the polymer mixture (II) containing reactive hydroxyl or hydrolysable groups bonded to silicon, which groups are reactive in the presence of moisture; 0.5 to 10 weight % of a crosslinker comprising at least three groups reactive with the silicon-bonded hydroxyl or hydrolysable groups of the polymer mixture; 15 to 35 weight % of the reinforcing filler; 3 to 35 weight % of the low-density filler, optionally hollow mineral microspheres; with the total filler content being 45% by volume of the composition; and tin based catalyst; and optionally, one or more additives; with the total composition being 100 weight %.

15. The two part moisture curing composition in accordance with claim 14, wherein the polymer mixture (II) further comprises polymer (iii), a siloxane polymer having terminal hydroxyl or hydrolysable groups and a viscosity of between 10 and 500 mPa.Math.s at 25 C.

16. A coating, sealing, caulking, mold making, or encapsulating material, said material comprising or formed from the two part moisture curing composition in accordance with claim 1.

17. An insulating glass sealant, a sealant in refrigerators or freezers, a sealant in an oven and/or a low thermally conductive coating on a substrate and/or a structural coating on a substrate comprising or formed from the two part moisture curing composition in accordance with claim 1.

18. An insulating glass unit and/or a building faade element and/or a structural glazing unit and/or a gas filled insulation construction panel which in each case is sealed with a secondary sealant cured from a silicone sealant composition, wherein the sealant composition comprises or is formed from the two part moisture curing composition in accordance with claim 1.

19. A process of making an insulating glass unit, said process comprising: procuring two glass panes; providing a spacer between the two glass panes; adhering the spacer to each pane of glass using a primary sealant; introducing into a cavity defined by the two glass panes and the spacer an inert or heavy gas; and applying a layer of a sealant composition as a secondary sealant around the periphery of the insulating glass unit in contact with external surfaces of the spacer; wherein the sealant composition comprises or is formed from the two part moisture curing composition in accordance with claim 1.

Description

EXAMPLES

(1) In the following examples Polymers (i), (ii) and (iii) were each dimethylhydroxy silyl terminated polydimethylsiloxanes, differing in viscosity as depicted in the Tables below. The treated precipitated calcium carbonate used was Winnofil SPM commercially available from Solvay. Three types of mineral microspheres were utilized. These were Sphericel 34P30 from Potters Industries LLC of Valley Forge, Pa., Sphericel 45P25 from Potters Industries LLC of Valley Forge, Pa. and 3M XLD3000.

(2) Mixing Procedure for Part A

(3) The Polymers were weighed in a 750 ml plastic container and mixed together in a speedmixer for 30 seconds at 2350 rpm. Half of the quantity of the treated precipitated calcium carbonate was added and mixed in the speedmixer with the polymer mixture twice for 30 seconds at 2350 rpm. The second half of the treated precipitated calcium carbonate was is then added and the mixing in the speedmixer was repeated as before. Half of the quantity of the hollow glass beads was then added and mixed with the resulting mixture from the above in the speedmixer twice for 30 seconds at 2350 rpm. The second half of the hollow glass is then added and mixed in a speedmixer three times for 30 seconds at 2350 rpm. The resulting product was then mixed for 50 seconds under vacuum in the speedmixer at 2350 rpm followed by 15 seconds at atmospheric pressure in the speedmixer at 2350 rpm. The resulting Part A of the composition was poured a 170 ml sealant cartridge for storage prior to use.

(4) Three different Part Bs were used to compare cured properties of examples:

(5) Catalyst 1 is Dow Corning 3362 HV catalyst, a tin based catalyst package commercially available from Dow Corning Corporation, Michigan, USA;

(6) Catalyst 2 is Dow Corning 994 catalyst a tin based catalyst package commercially available from Dow Corning Corporation, Michigan, USA; and

(7) Catalyst 3 is a catalyst composed of:

(8) 47.0% wt of tetraethoxy silane, 29.9% wt of vinyl terminated polydimethyl siloxane (viscosity at 23 C. ca 50,000 mPa.Math.s), 14.6% wt of carbon black, 6.7% wt of aminopropyl trimethoxysilane, 1.75% wt of Aerosil 974 from Evonik AG, 0.1% of wt dimethyl tin dineodecanoate.
Mixing Procedure for Part A and Part B

(9) 180 g of Part A (prepared previously as described above) was weighed in a 500 ml container. 18 g of the appropriate Part B was then added and mixed in a speedmixer for twice at 20 seconds at 2350 rpm. Finally, the mixture is mixed in the speedmixer for 30 seconds at 2350 rpm and transferred into a 170 ml Semco cartridge to facilitate application.

(10) Test pieces e.g. H-shaped pieces for tensile testing were provided by placing a suitable shaped mold on the non-tin side of a piece of float glass and introducing a predetermined amount of the above into a mold The resulting test pieces were allowed to cure for one day and then were demolded from the glass surface and the mold. The samples were then allowed to cure for a further 27 days. Tensile testing was performed. Hence, the cured properties were measured after 28 days of cure at 23 C. 50% relative humidity.

(11) Thermal Conductivity Measurement

(12) A sample of the Part A composition was applied between two polyethylene sheets in a quantity sufficient to make a test piece having a circular cross-section of 150 (+/1) mm diameter and 18 (+/1) mm thickness. The material applied was squeezed gently using the two plates to the thickness of 18 mm using Nordson Tapes 18 mm thick spacers at each corner of the plates.

(13) The test piece was then introduced into a Heat Flow Meter Lasercomp Fox 314 to perform thermal conductivity measurements according to ISO 8301: 1991. A temperature of 0 C. on the upper plate and 20 C. at the lower plate was set until an equilibrium state is achieved. The thickness (s) of the sample was averaged from the 4 corners automatically by the equipment. The heat flow (q) at the upper and lower plate must be equal and is used in the following equation to measure the thermal conductivity () of the sample.
=(q.Math.s)/(A.Math.T).
in which
s=the average thickness of the panel
A=is the surface area of the panel, and
T=temperature change ( C.)
The error of measurement was estimated to about 4%.
Extrusion Rate Measurement

(14) Extrudability was determined at 23 C. by measuring the rate of a part A sample that will extrude through a calibrated hole of 5.5 mm in diameter when applying a pressure of 6.22 bar (6.2210.sup.5 N/m.sup.2) on the plunger of a 310 ml Semco sealant cartridge. The results are reported in grams per minute.

(15) Slump Measurement (10 Minutes) Part A

(16) The slump behaviour of a sample of part A composition was determined by applying a test having a circular cross-section of 50 mm diameter and a thickness of 10 mm on a stainless steel substrate at 23 C. The substrate was moved into a vertical position and the distance by which the sample of part A composition moved under gravity forces after 10 minutes was recorded

(17) Tensile Properties

(18) Tensile properties were measured according to ISO 8339:2005 standard. The tensile properties of the previously prepared H-pieces were measured on a Zwick tensiometer at a speed of 5.5 mm/min until rupture. The results provided in Table 1 and 2 are an average of three tested samples.

(19) In Table 1 and 2 the ingredients are listed in parts and therefore are not required to add up to 100. For this case the amount present of each ingredient might be measured in grams, e.g. for example 1 of e.g. 50 g polymer (i) and 3 grams polymer (iii) etc.

(20) Total Filler Content (Solid Content) The total filler content by volume is determined by calculation based on the density of each ingredient (which was either provided by the supplier or determined in the laboratory) and then values of volume were extrapolated from the results, given the weight was known.

(21) TABLE-US-00001 TABLE 1 Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Part A formulation Polymer (i) 50,000 mPa .Math. s 50 50 50 50 50 50 50 20 80 Polymer (ii) 12,500 mPa .Math. s 50 50 50 50 50 50 50 80 20 Polymer (iii) 41 mPa .Math. s 3 3 3 3 3 3 3 3 3 Precipitated calcium carbonate 37 37 29 44 41 37 37 37 37 Sphericel 34P30 glass beads 19 19 22 15 19 19 19 Sphericel 45P25 glass beads 27 XLD3000 glass beads 12 Part B & (weight ratio Part A:Part B) Part B 1 10:1 10:1 10:1 10:1 10:1 10:1 10:1 Part B 2 10:1 Part B 3 10:1 Physical properties of base Thermal Conductivity (W/mK) 0.18 0.18 0.17 0.18 0.18 0.18 0.18 0.18 0.18 Extrusion rate (g/min) 71 76 67 56 59 98 76 99 52 Slump (mm) 25 24 48 7 8 48 24 24 16 Solid content (volume %) 38 38 38 38 41 34 38 38 38 Physical properties of the cured product Cohesive failure (%) 100 99 75 90 97 100 98 97 96 Tensile strength (MPa) 1.16 1.03 0.99 1.04 1.13 1.05 1.15 1.10 1.10 Elongation at break (%) 59 53 43 45 49 63 69 48 59

(22) TABLE-US-00002 TABLE 2 CEx1 CEx2 CEx3 CEx4 CEx5 CEx6 Part A formulation Polymer (i) 50,000 mP .Math. s 100 50 50 50 50 Polymer (ii) 12,500 mPa .Math. s 100 50 50 50 50 Polymer (iii) 41 mPa .Math. s 3 3 3 3 3 Precipitated calcium carbonate 37 37 37 37 37 50 Sphericel 34P30 glass beads 19 19 19 25 30 19 Part B (weight ratio Part A:Part B) Part B 1 10:1 10:1 10:1 10:1 10:1 10:1 Physical properties of base Thermal Conductivity (W/mK) 0.18 0.17 0.18 0.17 0.16 0.19 Extrusion rate (g/min) 44 113 63 49 30 63 Slump (mm) 21 >100 >100 11 5 4 Solid content (volume %) 38 38 39 43 47 40 Physical properties of the cured product Cohesive failure (%) 99 96 98 92 67 100 Tensile strength (MPa) 1.03 1.05 1.06 1.13 1.22 1.28 Elongation at break (%) 60 46 48 46 39 56

(23) Comparing all examples with comparative examples 1 it can be seen that replacing 50% of polymer (i) with Polymer (ii) (exhibiting a viscosity significantly below 50,000 mPa.Math.s at 25 C.), helps achieving an extrusion rate above 50 g/min.

(24) Comparing all examples with comparative example 2 it can be seen that incorporating a polymer exhibiting a viscosity around 50,000 mPa.Math.s at 25 C. helps provide a Part A formulation, which exhibits a limited slump. Having a Part A composition which exhibits high slump values will generally negatively affect the slump properties of the product resulting from mixing Part A and Part B.

(25) Comparing example 1 with comparative example 2 it can be seen that incorporating polymer (i) exhibiting a viscosity around 50,000 mPa.Math.s at 25 C. helps improve elongation at break.

(26) Comparing all examples with comparative example 3 it can be seen that incorporating optional Polymer (iii) having a very low viscosity 41 mPa.Math.s at 25 C. helps to achieve a Part A formulation, which exhibits a limited slump.

(27) Comparing example 1 with comparative example 5 it can be seen that increasing the solid content above 45 vol % (i.e. total filler content) results in reduced values for elongation at break.

(28) Comparing example 1 with comparative example 6 it can be seen that the addition of a high content of calcium carbonate is impairing thermal conductivity of the base.

(29) There are now provided a series of thermal simulations on high performance faade systems are showing that an insulating glass (IG) secondary sealant exhibiting a thermal conductivity below 0.2 W/mK according to EN 12667 could have a favourable impact on heat transfer coefficient(s) of a faade (often referred to as the U value).

(30) Thermal Simulations

(31) Thermal modelling was undertaken following the EN ISO 10077-2. standard method, using THERM 6.3 program for modelling complex glazing systems available from Lawrence Berkeley National Laboratory, USA.

(32) The modelling was undertaken for a standard window/glazing size of 1.23 m1.48 m and a standard size vision area of curtain wall of 1.5 m3.0 m.

(33) Three types of frames were modelled:

(34) a silicone structural glazed system (SSG),

(35) a captured system (CS, mechanical fixation) and

(36) a toggle system (TS).

(37) The three frames are based on state of the art frames available in Europe. The modelling of the toggle frame was done according to the procedure of EN ISO 10077-2 and the following assumptions were made concerning the amount of toggles per linear meter. For these results, we used 4 toggles per linear meter at an average toggle diameter of 13 mm, i.e. 413 mm=52 mm per linear meter of toggle. The remaining is frame without channel and without toggle.

(38) The use of a low thermal conductivity sealant for the secondary sealant of an IGU becomes interesting in optimized curtain wall systems, i.e. whereby a triple IGU is used, built up with a high efficiency (warm edge WE) spacer. Weatherseal or structural joints have been modelled with silicones at a standard thermal conductivity of 0.35 W/mK. as prescribed in the aforementioned THERM 6.3 program.

(39) A state of the art triple IGU with the following build-up was chosen: 6 mm low-e coated glass, a 14 mm argon filled cavity, an inner pane of 4 mm glass, a second cavity of 14 mm filled with argon and finally a 6 mm internal glass.

(40) This type of build-up reaches a center of glass U-value (heat transfer coefficient) of 0.7 W/m.sup.2K. This IGU was used for the SG and the mechanical fixed frame

(41) For the toggle frame, the build-up was slightly different and consisted of 6 mm low e-12 mm argon filled cavity-4 mm glass-20 mm argon filled cavity-8 mm glass but with the same U.sub.g (i.e. the U value for the center of glass)=0.7 W/m.sup.2K.

(42) For the modelling a warm edge spacer was used with linear thermal conductivity at 0.14 W/mK. Similar results can be expected when using different types of warm edge spacers.

(43) For the secondary sealant of the IGU, 3 different thermal conductivities were modelled for each frame:.

(44) The benchmark is a thermal conductivity of 0.35 W/mK. This corresponds with the value advised by EN ISO 10077 for silicone and was used for the weatherseal joint and/or structural glazing joint

(45) The second thermal conductivity value was 0.28 W/mK. This is representative for a Polyurethane (PU) sealant, and finally, a sealant with a thermal conductivity value of 0.19 W/mK was used. This corresponds to a material, which can be manufactured using the current invention described in this disclosure.

(46) The joint dimension for the secondary sealant was set at 6 mm which is frequently used as the joint dimension. The joint dimension in the IGU for the toggle system is slightly different, 6 mm depth for the first cavity and 12 mm depth, 6 mm thickness for the joints in the second cavity including the toggle.

(47) Ucw values were calculated for different frame systems and different thermal conductivities for a wall consisting of framed glazed units of 1.23 m by 1.48 m.

(48) The results can be found in Table 3 below. The U values for the curtain wall (Ucw) were rounded in accordance to EN ISO 10077-1.

(49) TABLE-US-00003 TABLE 3 Ucw (W/m.sup.2K) Ucw value value (W/m.sup.2K) Ucw value (W/m.sup.2K) when thermal when thermal when thermal conductivity = conductivity = conductivity = Frame 0.19 W/mK 0.28 W/mK 0.35 W/mK silicone structural 1.0 1.1 1.1 glazed system (SSG) captured system 0.99 1.0 1.0 (CS) Toggle System 1.0 1.1 1.1 (TS)

(50) The results show that changing the thermal conductivity of the secondary sealant has a significant impact on the resulting U.sub.cw for the curtain wall and the benefit can be gained by merely replacing a previous secondary sealant with the sealant composition as provided herein. A difference of up to 0.1 W/m.sup.2K is observed once the rounding to 1 significant digit for Ucw>1 W/m.sup.2K and to 2 significant digits for Ucw<1 W/m.sup.2K is done. This kind of improvement cannot be obtained with secondary sealants having a thermal conductivity superior or equal to 0.2 W/mK.

(51) Similarly, the results for curtain walls using a larger IGU of 1.5 m by 3.0 m was be studied as depicted in Table 4.

(52) TABLE-US-00004 TABLE 4 Ucw values as calculated for different frame systems and different thermal conductivities (units of 1.5 m 3.0 m) Ucw (W/m.sup.2K) value Ucw (W/m.sup.2K) value Ucw (W/m.sup.2K) value when when when thermal thermal thermal conductivity = conductivity = conductivity = frame 0.19 W/mK 0.28 W/mK 0.35 W/mK SSG 0.93 0.95 0.96 CS 0.90 0.91 0.92 TS 0.94 0.95 0.96

(53) The benefit of the secondary sealant as hereinbefore described is less pronounced in this case since there is relatively more highly efficient glazed surface than edge in the IGU.