WO2006025953A1

WO2006025953A1 - Products having reduced permeability and methods for the preparation and use of the products

Info

Publication number: WO2006025953A1
Application number: PCT/US2005/025085
Authority: WO
Inventors: Eric Jude Joffre; Robert Peter Mortensen; Rochelle Nesbitt
Original assignee: Dow Corning Corp
Current assignee: Dow Silicones Corp
Priority date: 2004-08-31
Filing date: 2005-07-15
Publication date: 2006-03-09
Anticipated expiration: 2007-02-28

Abstract

A method includes: 1) applying a barrier coating composition to a surface of a curable silicone composition before completion of surface cure of the curable silicone composition; and thereafter 2) curing the curable silicone composition to form a silicone. The barrier coating includes an organic polymer. The barrier coating adheres to the surface of the silicone and reduces moisture or gas permeability.

Description

DESCRIPTION

PRODUCTS HAVING REDUCED PERMEABILITY AND METHODS FOR THE PREPARATION AND USE OF THE PRODUCTS

Cross Reference [0001] This application claims the benefit of U.S. Provisional Application Serial No.

60/606021, filed on 31 August 2004 under 35 U.S.C. §119(e). U.S. Provisional Application Serial No. 60/606021 is hereby incorporated by reference.

Technical Field

[0002] This invention relates to a product having low moisture permeability or low gas permeability, or both. The product is a silicone having a barrier coating that lowers permeability as compared to the uncoated silicone. The product finds use in insulating glass units.

Background

[0003] Silicones, such as silicone elastomers, may suffer from high moisture permeability or high gas permeability, or both. High moisture permeability may allow moisture to collect between the glass panes in an insulating glass unit, which can result in misting of the panes. In one method proposed for lowering moisture permeability and gas permeability of silicones, a vapor barrier filler such as mica, talc, or a combination thereof is incorporated in a curable silicone composition to reduce moisture vapor transmission. However, this method suffers from the drawback that high levels of the vapor barrier filler may result in a curable silicone composition that is difficult to handle and that may cure to form a silicone having undesirably high modulus. Lower levels of the vapor barrier filler may not provide sufficient lowering of moisture permeability, gas permeability, or both.

[0004] Barrier coatings have been proposed to reduce moisture permeability and gas permeability of various organic materials, such as organic elastomers. However, silicones typically have low surface energy, which makes adhesion of a barrier coating difficult.

Problem to be Solved

[0005] Therefore, the problem to be solved is to provide a silicone having a barrier coating adhered to the silicone to produce a product having low moisture permeability, low gas permeability, or both. Means for Solving the Problem

[0006] A barrier coating may be adhered to a silicone by applying a barrier coating composition to a curable silicone composition before completion of surface cure of the curable silicone composition. Curing the resulting coated curable silicone composition may provide a product having reduced moisture permeability, reduced gas permeability, or both.

Summary

[0007] A method comprises:

1) applying a barrier coating composition to a surface of a curable silicone composition before completion of surface cure of the curable silicone composition; and thereafter 2) curing the curable silicone composition to form a silicone.

Detailed Description

[0008] All amounts, ratios, and percentages are by weight unless otherwise indicated. The following is a list of definitions, as used herein.

Definitions and Usage of Terms [0009] "A" and "an" each mean one or more.

[0010] "Combination" means two or more items put together by any means or method. [0011] "Surface cure" means substantial completion of a chemical process by which molecules at the interface of a curable composition and ambient air are joined to other molecules by crosslinking into larger molecules to restrict molecular movements. [0012] "Silicone elastomer" means a generally nontacky silicone having the consistency of rubber. Silicone elastomers are more highly crosslinked than silicone gels. [0013] "Fisheyes" are flaws in the surface of a barrier coating allowing the silicone underneath to be visible to the naked eye. [0014] "Surfactant" means a component in a combination that reduces surface tension of the combination.

Curable Silicone Composition

[0015] Suitable curable silicone compositions, methods for their preparation, and the silicones obtained by curing them are known in the art. Silicone compositions having various cure mechanisms may be used. Suitable cure mechanisms include, but are not limited to moisture curable compositions; condensation-reaction curable compositions, e.g., oxime curable, acetoxy curable, etc.; peroxide curable compositions; and hydrosilylation curable compositions. For example, the curable silicone compositions disclosed in GB 2 249 552 A are suitable for use in this invention. The moisture curable silicone compositions disclosed in U.S. Patents 4,962,076; 5,051,455; and 5,053,442 are also suitable for use in this invention. The portions of U.S. Patents 4,962,076; 5,051,455; and 5,053,442 disclosing moisture curable silicone compositions are hereby incorporated by reference. [0016] An example of a moisture curable silicone composition suitable for use in this invention comprises: (i) a base polymer, (ii) a crosslinker, (iii) a catalyst, optionally (iv) a filler, optionally (v) a filler treating agent, optionally (vi) an adhesion promoter, and optionally (vii) a pigment.

[0017] Component (i) is a base polymer. Component (i) may be a polyorganosiloxane having moisture reactive functional groups, such as hydroxyl groups, alkoxy groups, or a combination thereof. Component (i) may comprise an alkoxy-endblocked polydiorganosiloxane, a trialkoxysilethylene-endblocked polydiorganosiloxane, a hydroxyl- endblocked polydiorganosiloxane, or a combination thereof. Examples of suitable base polymers include a vinyl-terminated, polydimethylsiloxane reaction product with (trimethoxysilylethyl)tetramethyldisiloxane and are disclosed in U.S. Patents 4,962,076; 5,051,455; and 5,053,442.

[0018] Component (ii) is a crosslinker added to the curable silicone composition in an amount sufficient cure the curable silicone composition. Component (ii) may comprise an alkoxysilane, a dialkoxysilane, such as a dialkyldialkoxysilane; a trialkoxysilane, such as an alkyltrialkoxysilane; a tetraalkoxysilane; or partial or full hydrolysis products thereof or other combination thereof. Examples of suitable alkoxysilanes may have the general formula R¹ _aSi(OR²)_4-a, where each R¹ is independently a monovalent hydrocarbon group such as an alkyl group, each R² is independently an alkyl group of 1 to 6, alternatively 1 to 4, carbon atoms, and a is 2, 3, or 4. Examples of suitable trialkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and combinations thereof, and alternatively methyltrimethoxysilane. Examples of suitable tetraalkoxysilanes include tetraethoxysilane. Examples of crosslinkers are disclosed in U.S. Patents 4,962,076; 5,051,455; and 5,053,442.

[0019] Component (iii) is a catalyst added to the curable silicone composition in an amount sufficient to promote cure of the curable silicone composition. Component (iii) may comprise a tin catalyst, a titanium catalyst, or a combination thereof. Suitable tin catalysts include, but are not limited to dibutyl tin dilaurate, dibutyl tin oxide, stannous octoate, tin oxide, and combinations thereof. Suitable titanium catalysts include, but are not limited to, a chelated titanium compound, a tetraalkoxytitanate, or a combination thereof. Examples of suitable titanium catalysts include, but are not limited to, diisopropoxytitanium bis(ethylacetoacetate), tetrabutoxy titanate, and combinations thereof. Examples of catalysts are disclosed in U.S. Patents 4,962,076; 5,051,455; and 5,053,442.

[0020] Component (iv) is an optional component that may be added to the curable silicone composition. Component (iv) is a filler that may comprise aluminum oxide, calcium carbonate, carbon, chromic oxide, clay, diatomaceous earth, graphite, iron oxide, glass fibers, magnesium oxide, mica, quartz, quartz carbon, silica, talc, titanium dioxide, zinc oxide, zirconium oxide, zirconium silicate, a combination thereof, or a filler disclosed as component (B) of the barrier coating composition, in addition to, or instead of all or a portion of fillers exemplified above. Examples of fillers are disclosed in U.S. Patents 5,051,455 and 5,053,442. [0021] Component (iv) may optionally be surface treated with component (v), a filler treating agent. The filler may be treated with the filler treating agent before the filler is added to the composition, or in situ. Component (v) may comprise a cyclic polyorganosiloxane or a fatty acid such as an oleic acid, a stearate, a stearic acid, or a combination thereof. Examples of cyclic polyorganosiloxanes include octamethylcyclotetrasiloxane. Examples of stearates include calcium stearate. Examples of filler treating agents are disclosed in U.S. Patents 5,051,455 and 5,053,442.

[0022] Component (vi) is an optional component that may be added to the curable silicone composition. Component (vi) is an adhesion promoter. Component (vi) may comprise an amino-functional alkoxysilane (different from the alkoxysilane used as component (ii)), a mercapto-functional compound, or a combination thereof. Suitable amino-functional alkoxysilanes include gamma-aminopropyltriethoxysilane, gamma- aminopropyltrimethoxysilane, (ethylenediaminepropyl)trimethoxysilane, and combinations thereof. Suitable mercapto-functional compounds include an organomercaptan, a mercapto containing silane, or a combination thereof. Suitable mercapto containing silanes include 3- mercaptoproyltrimethoxysilane. Suitable mercapto-functional compounds are disclosed in U.S. Patent 4,962,076. [0023] Component (vii) is an optional component that may be added to the curable silicone composition. Component (vii) comprises a pigment such as carbon black. Examples of pigments are disclosed in U.S. Patents 4,962,076; 5,051,455; and 5,053,442.

Barrier Coating Composition [0024] Suitable barrier coating compositions and the barrier coatings obtained therefrom are known in the art, see for example, U.S. Patent 6,087,016, which is hereby incorporated by reference for the purpose of disclosing suitable barrier coating compositions and the barrier coatings obtained therefrom. The barrier coating composition used in this invention may comprise: (A) an organic polymer, optionally (B) an exfoliated layer platelet-like filler, (C) a surfactant, optionally (D) a pH adjusting agent, optionally (E) a thickener, optionally (F) a cure package, and optionally (G) a carrier.

[0025] The solids content of this barrier coating composition may be less than 30%, alternatively 5 to 17%. The ratio of (A) the elastomeric polymer to (B) the filler may be 20: 1 to 1:1. [0026] Component (A) may be present in the barrier coating composition an amount of 1 to 30% (and 45 to 95% in the barrier coating formed from the barrier coating composition). [0027] Component (A) may comprise a curable polymer, a partially cured polymer, or an uncured polymer. Component (A) may be free of fluorinated species. Component (A) includes without limitation, olefinic thermoplastic elastomer; polyamide thermoplastic elastomer; polybutadiene thermoplastic elastomer, e.g., syndiotactic 1,2-polybutadiene thermoplastic elastomer; polyester thermoplastic elastomer; polyurethane thermoplastic elastomer, e.g., thermoplastic polyester-polyurethane elastomer, thermoplastic polyether- polyurethane elastomer; styrenic thermoplastic elastomer; vinyl thermoplastic elastomer, e.g., polyvinyl chloride polyol, polyvinylidene chloride; and combinations thereof. [0028] Alternatively, component (A) may comprise a rubber polymer including acrylic rubber, e.g., ethylene-acrylate copolymer; or butadiene rubber, e.g., polybutadiene. Butyl- containing polymers useful as component (A) may include, without limitation, curable, partially cured, or uncured butyl rubber, such as isobutylene-isoprene copolymer; bromobutyl rubber, e.g., bromoisobutylene-isoprene copolymer; chlorobutyl rubber, e.g., chloroisobutylene-isoprene copolymer; and isobutylene rubber. [0029] Alternatively, component (A) may comprise chlorosulfonated polyethylene rubber, e.g., chlorosulfonated polyethylene; epichlorhydrin rubber; ethylene-propylene rubber; e.g., ethylene-propylene copolymer or ethylene-propylene-diene copolymer. [0030] Alternatively, component (A) may comprise an elastomer such as neoprene rubber, e.g., polychloroprene; nitrile rubber, e.g., acrylonitrile-butadiene copolymer; polyisoprene rubber; polysulfide rubber; polyurethane; propylene oxide rubber; and styrene-butadiene rubber, e.g., styrene-butadiene copolymer.

[0031] Component (A) may have the form of a solution, dispersion, latex, suspension, or emulsion in water, solvent, or a combination thereof.

[0032] Component (B) is an optional filler that may be added to the barrier coating composition. Component (B) may be present in the barrier coating composition at 1 to 10% (and 5 to 55% in the barrier coating formed from the barrier coating composition).

Component (B) may have an aspect ratio greater than 25, alternatively greater than 100, alternatively 25 to 30,000, and alternatively 100 to 30,000.

[0033] Component (B) may comprise an exfoliated layered platelet filler. Component (B) may comprise a filler having a flake form. Suitable fillers include, but are not limited to aluminum, layered silicates, mica, and combinations thereof. Suitable layered silicates are exemplified by beidellite, bentonite, hectorite, kenyaite, laponite, ledikite, magadiite, montmorillonite, nontronite, saponite, sauconite, vermiculite, volkonskoite, and combinations thereof. Alternatively, component (B) may comprise mica, vermiculite, and combinations thereof. [0034] Component (C) is a surfactant such as an anti-foaming agent, dispersing agent, emulsifier, leveling agent, wetting agent, or combination thereof. Component (C) may comprise an anionic surfactant, a cationic surfactant, or a nonionic surfactant. Alternatively, component (C) may comprise a wetting agent and an anti-foaming agent. Component (C) may be added in an amount sufficient to provide up to 10% of the barrier coating prepared from the barrier coating composition.

[0035] The composition may further comprise an optional component. Examples of suitable optional components include (D) a pH adjusting agent, (E) a thickener, (F) a cure package, (G) a carrier, and combinations thereof.

[0036] Component (D) is a pH adjusting agent. Component (D) may be an acid or base added to prevent agglomeration of component (B). Component (D) may be added in an amount sufficient to provide the barrier coating composition with a pH of 8 to 11. [0037] Component (E) is a thickener. Component (E) may be used to control viscosity of a barrier coating composition. Component (E) may comprise lithium chloride, a polyvinyl alcohol terpolymer, or xanthan gum, e.g., Keltrol xanthan gum, which is commercially available from CP Kelco. Component (E) may be present in an amount of 0.3% to 5.5%, alternatively 3% to 5.5%, based on the weight of the barrier coating composition. [0038] Without wishing to be bound by theory, it is thought that viscosity of the barrier coating composition may be controlled to prevent fisheyes in the barrier coating formed from the barrier coating composition. The exact viscosity selected will depend on various factors including the surface energy of the particular curable silicone composition and the particular barrier coating composition selected, however, a suitable barrier coating compositions, such as those disclosed in examples 1-5, infra, may have a viscosity of 1,000 to 5,000; alternatively 3,000 to 5,000 centiPoise (measured with a Brookfield viscometer at 0.3 revolutions per minute at 23 °C.) when applied to a curable silicone composition, such as that in reference example 1, infra. One skilled in the art would be able to select an appropriate viscosity for the barrier coating composition without undue experimentation. [0039] Component (F) is an optional component that can be used to affect curing of a curable barrier coating composition. One skilled in the art would be able to select an appropriate cure package, and amount thereof, depending on the cure mechanism selected for the barrier coating composition. [0040] Component (G) is a carrier in which the other components of the barrier coating composition may be dissolved or dispersed. Suitable carriers include, without limitation, water and organic solvents such as hydrocarbons, and combinations thereof. [0041] Suitable barrier coating compositions are commercially available from, for example, InMat, Inc. of Hillsoborugh, New Jersey, U.S.A. and include AIR D-FENSE® 2000 and AIR D-FENSE® 3500 S, both of which are butyl rubber dispersions advertised at www.inmat.com/productspecs-temp.htm. Other suitable barrier coating compositions include vinylidene chloride copolymer dispersions such as SERFENE® 400, available from Rohm & Haas of Philadelphia, Pennsylvania, U.S.A., and DIOF AN® A050, available from Solvin, a division of Solvay Polymers, Inc. of Houston, Texas, 77227, U.S.A.

Methods of Making the Product [0042] The product of this invention may be prepared by a method comprising: 1) applying the barrier coating composition to a surface of the curable silicone composition before completion of surface cure of the curable silicone composition; and thereafter 2) curing the curable silicone composition to form a silicone.

[0043] The barrier coating composition may be applied to the curable silicone composition by any convenient means, such as dip coating, spraying, or brushing. Curing the curable silicone composition may be performed by any convenient means depending on the cure mechanism of the curable silicone composition selected. For example, curing may be performed by exposing the curable silicone composition to moisture, heat, UV radiation, or combinations thereof. [0044] The method of this invention may optionally further comprise: 3) sealing an insulating glass unit with the product of step 2).

[0045] The amount of barrier coating composition depends on various factors including the type of barrier coating composition, the type of curable silicone composition, and the end use of the product. However, the amount of barrier coating composition is sufficient to form a barrier coating that reduces moisture permeability or gas permeability, or both, of the product of step 2). The barrier coating may have a thickness of 0.5 mil (0.01 millimeter) to 10 mils (0.3 mm), alternatively 1 mil (0.02 mm) to 3 mils (0.08 mm), in the product of step 2). [0046] The barrier coating composition is applied to the surface of the curable silicone composition before completion of surface cure of the curable silicone composition, i.e., before the surface is cured. The exact timing for application of the barrier coating composition depends on various factors including the cure speed of the specific curable silicone composition selected and the specific barrier coating composition selected. For example, when AIR D-FENSE® 2000 is used as the barrier coating composition for the moisture curable silicone composition described in reference example 1, infra, timing for application of the AIR D-FENSE® 2000 may be 6 to 10 minutes after beginning exposure of the moisture curable silicone composition to atmospheric moisture. One skilled in the art would be able to determine the timing for application of the barrier coating composition to the curable silicone composition without undue experimentation.

Methods of Use of the Product

[0047] The product of this invention may be used for sealing an insulating glass unit. For example, the product may be used as a secondary sealant in an insulating glass unit, such as the unit shown in Figure 1. The barrier coating composition used to form the barrier coating 101 may be applied to the curable silicone composition used to form the silicone 102 at any time before, during, or after applying the curable silicone composition to the glass panes 105 and spacer 104, which is secured to the glass panes 105 by a primary seal 103. [0048] When the product of this invention is used for sealing an insulating glass unit, the silicone may be a silicone elastomer, and the barrier coating may be an organic elastomer. Using a silicone elastomer and an organic elastomer may provide flexibility and improved product life when the insulating glass unit is exposed to ambient temperature conditions that may cause the insulating glass unit to expand and contract.

Examples [0049] These examples are intended to illustrate the invention to one skilled in the art and should not be interpreted as limiting the scope of the invention set forth in the claims.

Comparative Example 1

[0050] A film of a curable silicone composition, DOW CORNING® 3-0117 Insulating Glass Sealant, which is commercially available from Dow Corning Corporation of Midland, Michigan, 48686, U.S.A., is cured. The oxygen permeability of the resulting cured silicone is measured using a Mocon Ox-tran 2/20 analyzer (Mocon). The permeability is 7358 x 10¹⁰ cm -mm/^rnHg-cm .s).

Comparative Example 2

[0051] A slab of the curable silicone composition prepared in reference example 1 is cured. AIR D-FENSE® 2000, is applied by brush to the resulting silicone when it is 21 days old. The AIR D-FENSE® 2000 coating does not wet the surface of the silicone and make a uniform coating, as evidenced by fisheyes forming in the AIR D-FENSE® 2000 coating surface. Example 1

[0052] A barrier coating composition is prepared by adding 1.05 grams (g) of Keltrol xanthan gum (CP Kelco) to 300 g of SERPENE® 400 vinylidene chloride copolymer dispersion (Rohm & Haas) and mixing until dispersed. The resulting thickened dispersion is applied to a film of uncured DOW CORNING® 3-0117 Insulating Glass Sealant two minutes after drawdown, using a disposable nylon brush. The barrier coating composition does not form fϊsheyes on the curable silicone composition. The barrier coating composition dries to a continuous film. [0053] The curable silicone composition is then cured. The oxygen permeability of the resulting product is measured using a Mocon Ox-tran 2/20 analyzer (Mocon). The permeability is 236 x 10¹⁰ cm^{3 •}mm/(cmHg-cm².s). This permeability is 3% of the uncoated control in comparative example 1.

Example 2 [0054] A barrier coating composition is prepared by adding, 1.05 g of Keltrol xanthan gum (CP Kelco) to 300 g of Diofan A050 PVDC dispersion (Solvin) and mixing until dispersed. The resulting thickened dispersion is applied to a film of uncured DOW CORNING® 3-0117 Insulating Glass Sealant two minutes after drawdown, using a disposable brush. The barrier coating composition does not form fϊsheyes on the curable silicone composition. The barrier coating composition dries to a continuous film. [0055] The curable silicone composition is then cured. The oxygen permeability of the resulting product is measured using a Mocon Ox-tran 2/20 analyzer (Mocon). The permeability is 719 x 10¹⁰ cm³-mm/(cmHg-cm².s). This permeability was 10% of the uncoated control in comparative example 1.

Example 3 [0056] A commercially available barrier coating composition, AIR D-FENSE® 2000, is applied as supplied to a film of uncured DOW CORNING® 3-0117 Insulating Glass Sealant ten minutes after drawdown, using a disposable brush. The barrier coating composition does not form fisheyes on the curable silicone composition. The barrier coating composition dries to a continuous film. [0057] The curable silicone composition is then cured. The oxygen permeability of the resulting product is measured using a Mocon Ox-tran 2/20 analyzer (Mocon). The permeability is 98 x 10¹⁰ cm³ -mm/(cmHg-cm².s). This permeability is 1% of the uncoated control in comparative example 1.

Example 4

[0058] A commercially available barrier coating composition, AIR D-FENSE® 2000, is applied as supplied to a film of uncured DOW CORNING® 3-0117 Insulating Glass Sealant ten minutes after drawdown, using a sprayer. The barrier coating composition does not form fisheyes on the curable silicone composition. The barrier coating composition dries to a continuous film.

[0059] The curable silicone composition is then cured. The oxygen permeability of the resulting product is measured using a Mocon Ox-tran 2/20 analyzer (Mocon). The permeability is 150 x 10¹⁰ cm³-mm/(cmHg-cm².s). This permeability is 2% of the uncoated control in comparative example 1.

Example 5

[0060] A commercially available barrier coating composition, AIR D-FENSE® 2000, is applied as supplied to a film of uncured DOW CORNING® 3-0117 Insulating Glass Sealant ten minutes after drawdown, using a disposable brush. The barrier coating composition does not form fisheyes on the curable silicone composition. The barrier coating composition dries to a continuous film. A second coat of the barrier coating composition is applied the following day. [0061] The oxygen permeability of a sample of the coated cured silicone is measured using a Mocon Ox-tran 2/20 analyzer (Mocon) after 1000 hours of exposure to ultra-violet light from a QUV exposure device using a cycle of 4 hours (hrs) 50 °C (condensation)/4 hrs 60 ⁰C

340 nanometer (nm) light. The permeability is 495 x 10¹⁰ cm³-mm/(cmHg-cm².s). This permeability is 6% of the uncoated, unexposed control in comparative example 1. Industrial Applicability

[0062] These examples show that the barrier coatings significantly reduce oxygen permeability of the cured silicone prepared from the composition in comparative example 1.

The product including a barrier coating adhered to a silicone is suitable for use as a secondary sealant in insulating glass units. DRAWINGS

[0063] Figure 1 shows an end portion of an insulating glass unit of this invention.

101 barrier coating

102 silicone

103 primary seal

104 spacer

105 glass pane

Claims

1. A method comprising:

1) applying a barrier coating composition to a surface of a curable silicone composition before completion of surface cure of the curable silicone composition; and thereafter

2) curing the curable silicone composition to form a silicone.

2. The method of claim 1, where the barrier coating composition comprises: (A) an organic polymer, optionally (B) an exfoliated layer platelet-like filler, (C) a surfactant, optionally (D) a pH adjusting agent, optionally (E) a thickener, optionally (F) a cure package, and optionally (G) a carrier.

3. The method of claim 1, where the curable silicone composition is a moisture curable silicone composition comprising: (A) a base polymer, (B) a crosslinker, (C) a catalyst, optionally (D) a filler, optionally (E) a filler treating agent, optionally (F) a color reducing additive, and optionally (G) a pigment.

4. The method of claim 1, further comprising: 3) sealing an insulating glass unit with the product of step 2).

5. An insulating glass unit comprising i) at least two spaced glass panes, ii) sealing means between the at least two spaced glass panes, where at least a part of the sealing means comprises a product of the method claimed in any one of claims 1 to 4.

6. A product comprising:

(A) a barrier coating comprising an organic polymer,

(B) a silicone elastomer having a surface, where the barrier coating is adhered to the surface of the silicone elastomer.

7. The product of claim 6, where the organic polymer comprises polyvinylidene chloride.

8. The product of claim 6, where the organic polymer comprises butyl rubber.

9. The product of claim 6, where the silicone elastomer is a reaction product of a curable silicone composition comprising: (A) a base polymer selected from the group consisting of an alkoxy-endblocked polydiorganosiloxane, a trialkoxysilethylene-endblocked polydiorganosiloxane, a hydroxyl- endblocked polydiorganosiloxane, and a combination thereof;

(B) a crosslinker selected from the group consisting of trialkoxysilane, a dialkyldialkoxysilane, and a combination thereof; (C) a catalyst selected from the group consisting of a chelated titanium compound, a tetraalkoxytitanate, and a combination thereof;

(D) a filler selected from the group consisting of calcium carbonate, silica, quartz, and a combination thereof;

(E) a filler treating agent selected from the group consisting of a stearate, a stearic acid, or a combination thereof;

(F) a mercapto-functional compound selected from the group consisting of an organomercaptan, a mercapto containing silane, and a combination thereof; and

(G) a pigment comprising carbon black.

10. An insulating glass unit comprising: i) at least two spaced glass panes, ii) sealing means between the at least two spaced glass panes, where at least a part of the sealing means comprises the product of any one of claims 6 to 9.