Silicone Composition and Its Preparation

Abstract

The present invention relates to a process for preparing a one-component translucent room temperature vulcanizable (RTV) silicone composition comprising a chain-extended alkoxy endblocked polydiorganosiloxane polymer and a tin-based catalyst. The process produces a one-component translucent room temperature vulcanizable (RTV) silicone composition that is storage stable in the absence of moisture and curable in the presence of atmospheric moisture at ambient temperature. It has been unexpectedly found that the one-component translucent room temperature vulcanizable (RTV) silicone composition obtained from the process has excellent adhesive properties to polyvinyl chloride (PVC) substrates.

Description

[Technical field]

[0001] The present invention relates to a process for preparing a one-component translucent room temperature vulcanisable (RTV) silicone composition comprising a chain-extended alkoxy endblocked polydiorganosiloxane polymer and a tin-based catalyst. The process produces a one-component translucent room temperature vulcanisable (RTV) silicone composition that is storage stable in the absence of moisture and curable in the presence of atmospheric moisture at ambient temperature. It has been unexpectedly found that the one-component translucent room temperature vulcanisable (RTV) silicone composition resulting from the process has excellent adhesion properties to polyvinyl chloride (PVC) substrates. [Background technology]

[0002] Room temperature vulcanizable (RTV) silicone rubber compositions (hereinafter referred to as "RTV compositions") are well known. Generally, such compositions include: an -OH endblocked diorganopolysiloxane polymer or an alkoxy endblocked polydiorganosiloxane polymer, which may have an alkylene bond to a terminal silicon atom; and one or more suitable cross-linking agents.

[0003] The crosslinking agents are designed to react with the -OH and / or alkoxy groups of the respective polymers, thereby crosslinking the composition to form an elastomeric product. One or more additional materials, such as catalysts, reinforcing fillers, non-reinforcing fillers, plasticizers / extenders, flame retardants, solvent resistance additives, biocides, and the like, are also often incorporated into these compositions as needed.

[0004] Several routes are known in the art for preparing polydiorganosiloxane polymers with alkoxy end groups, for example by reacting di-, tri-, or tetraalkoxysilanes (polyalkoxysilanes) with silanol-terminated polydiorganosiloxane polymers in the presence of a catalyst. As might be expected, this reaction is not straightforward. In fact, silanol groups do not readily react with alkoxysilane groups at ambient temperature in the absence of a catalyst. A wide variety of compounds have been proposed as suitable catalysts for this purpose. Some, such as sulfuric acid, hydrochloric acid, Lewis acids, sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide, are generally chemically harsh and have been found to cause bond scission and random rearrangement when involved in the condensation of silanols with alkoxysilanes. Lithium hydroxide is an inorganic solid and requires a polar solvent, such as methanol, to be introduced into the reaction as a solution. However, the presence of methanol continuously regenerates the catalyst, for example in the form of lithium methoxide, so that the resulting polymeric reaction product exhibits a rapid viscosity drop due to interaction with the regenerated lithium catalyst. Additionally, many of these catalysts can emit unpleasant odors and are hazardous to the eyes and skin, yet their removal is often difficult, requiring tedious and costly extra steps.

[0005] Silicone sealant compositions that have at least one Si-alkoxy bond, for example, Si-methoxy bond in terminal reactive silyl group, and have polydiorganosiloxane polymer backbone are widely used in construction industry sealants, because they have low viscosity and good moisture permeability and weather resistance.In construction industry, one-component composition is generally preferred, because it does not need to mix components immediately before application on target substrate, and provides composition with excellent workability.

[0006] Such sealant compositions are often provided to create a low modulus cured product that can be highly stretched and contracted by small amounts of stress. Low modulus room temperature vulcanizable (RTV) silicone compositions can be used in a wide variety of applications. For example, they have achieved considerable commercial success as highway sealants and, more recently, in the construction of high-rise buildings. In the case of high-rise building construction, it is desirable, and often crucial, for both aesthetic and energy-saving reasons to utilize low modulus sealants and / or adhesives to bond window panes to their respective frames (metal or PVC) of the building structure, or for use in the construction of "mirrored" high-rise buildings, i.e., high-rise buildings whose exteriors have the appearance of large mirrors. The low modulus property allows the resulting cured silicone elastomer to easily compress and expand due to building movement, such as wind, without causing cohesive or adhesive failure.

[0007] Low modulus sealants typically rely on high molecular weight / chain length polydiorganosiloxane polymers that are end-capped with reactive groups but have a low level of reactive groups attached to silicon atoms along the polymer chain to produce crosslinked elastomeric products with low crosslink density. Such polymers are often prepared using a chain extension process in which a suitable reactive silane can be utilized as a chain extender during the curing of the composition.

[0008] For example, U.S. Patent Application Publication No. 2004 / 0122199 discloses a chain extended polymer product and a method for producing the same using at least one dialkylaminomethylalkyldialkoxysilane chain extender, which results in a chain extension linkage between -OH terminated polymer starting materials or the like of:

[0009] [ka] In U.S. Patent Application Publication No. 2004 / 0122199, the terminal -OH groups of the resulting chain extended polymer may then be endblocked with alkoxy groups as described above, and the reader is advised that the resulting chain extended polymer will have improved storage stability and increased viscosity.

[0010] Chain extension is also utilized in some two-part silicone sealant compositions. For example, US Patent No. 5,290,826 describes another use of chain-extended polymers in an ultra-low modulus two-part sealant composition that cures rapidly in depth when two parts are mixed together. The first part consists essentially of a hydroxyl endblocked polydiorganosiloxane, a non-reinforcing non-acidic filler, a diacetamidosilane chain extender, and an aminoxy silicone compound, and the second part consists essentially of a hydroxyl endblocked polydiorganosiloxane, a non-reinforcing non-acidic filler, and water. When mixed together, the resulting composition cures rapidly in depth and the polymer is not endcapped. In this case, the chain-extended bond formed between the two -OH terminated polymer starting materials is different and is provided below.

[0011] [ka]

[0012] Unfortunately, however, many one-component compositions (e.g., one-component alkoxy translucent sealant compositions) are well known to have poor adhesion properties to PVC. This has proven to be a long-term problem given the desire to use low modulus sealants in the construction of high rise buildings, as they can be easily compressed and expanded by building movement, such as from wind, without causing cohesive or adhesive failure.

[0013] 1. A process for preparing a one-component translucent room temperature vulcanizable (RTV) silicone composition, comprising: (i) chain extending the silanol terminated polydiorganosiloxane (ai) by reacting the silanol terminated polydiorganosiloxane (ai) with a diacetamidosilane chain extender (aii) to form a chain extended silanol terminated polydiorganosiloxane intermediate (aiii); (ii) reacting the chain extended silanol terminated polydiorganosiloxane intermediate (aiii) of step (i) with a silanol-terminated polydiorganosiloxane having the structure (R 2 -O) (4-b) -Si-R 1 b (wherein b is 0, 1 or 2; R 2 is an alkyl group having 1 to 15 carbons, which may be linear or branched; R 1 may be any suitable group, i.e. R 2 cycloalkyl groups; alkenyl groups, aryl groups; aralkyl groups, aminoalkyl groups, (meth)acrylate groups, glycidyl ether groups, and groups obtained by replacing all or a portion of the hydrogens in the aforementioned organic groups with halogens) in the presence of a basic endblocking catalyst (av) to form a chain extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a); (iii) introducing a crosslinker (b), an optionally hydrophobically treated reinforcing silica filler (c), one or more adhesion promoters (e), and one or more tin-based condensation catalysts (f) into the chain-extended alkoxy endblocked polydiorganosiloxane polymer (a), in any suitable order, to form a mixture; (iv) vacuum stripping the mixture of step (iii); (v) introducing one or more moisture scavengers (d).

[0014] 1. A one-component translucent room temperature vulcanizable (RTV) silicone composition comprising: (i) chain extending the silanol terminated polydiorganosiloxane (ai) by reacting the silanol terminated polydiorganosiloxane (ai) with a diacetamidosilane chain extender (aii) to form a chain extended silanol terminated polydiorganosiloxane intermediate (aiii); (ii) reacting the chain extended silanol terminated polydiorganosiloxane intermediate (aiii) of step (i) with a silanol-terminated polydiorganosiloxane having the structure (R 2 -O) (4-b) -Si-R 1 b (In the formula, b is 0, 1 or 2; R 2 is an alkyl group having 1 to 15 carbons, which may be linear or branched; R 1 is any suitable group, i.e. R 2 cycloalkyl groups; alkenyl groups, aryl groups; aralkyl groups, aminoalkyl groups, (meth)acrylate groups, glycidyl ether groups, and groups obtained by replacing all or a portion of the hydrogens in the aforementioned organic groups with halogens) in the presence of a basic endblocking catalyst (av) to form a chain extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a); (iii) introducing a crosslinker (b), an optionally hydrophobically treated reinforcing silica filler (c), one or more adhesion promoters (e), and one or more tin-based condensation catalysts (f) into the chain-extended alkoxy endblocked polydiorganosiloxane polymer (a), in any suitable order, to form a mixture; (iv) vacuum stripping the mixture of step (iii); (v) incorporating one or more moisture scavengers (d).

[0015] 1. A one-component translucent room temperature vulcanizable (RTV) silicone composition comprising: (a) the following process; (i) chain extending the silanol terminated polydiorganosiloxane (ai) by reacting the silanol terminated polydiorganosiloxane (ai) with a diacetamidosilane chain extender (aii) to form a chain extended silanol terminated polydiorganosiloxane intermediate (aiii); (ii) reacting the chain extended silanol terminated polydiorganosiloxane intermediate (aiii) of step (i) with a silanol-terminated polydiorganosiloxane having the structure (R 2 -O) (4-b) -Si-R 1 b (wherein b is 0, 1 or 2; R 2 is an alkyl group having 1 to 15 carbons, which may be linear or branched; R 1 may be any suitable group, i.e. R 2 a monovalent hydrocarbon radical such as, for example, a cycloalkyl group; an alkenyl group; an aryl group; an aralkyl group; an aminoalkyl group; a (meth)acrylate group; a glycidyl ether group; and groups obtained by replacing all or a portion of the hydrogens in the aforementioned organic groups with halogens) in the presence of a basic endblocking catalyst (av), (b) a cross-linking agent; (c) a reinforcing silica filler, which may optionally be hydrophobically treated; and (d) one or more moisture scavengers; (e) one or more adhesion promoters; Provided herein is a one-component translucent room temperature vulcanizable (RTV) silicone composition comprising, together with (f) a tin-based catalyst.

[0016] Also provided is a cured sealant product that is a cured product of the above.

[0017] There is also provided the use of a one-component translucent room temperature vulcanizable (RTV) silicone composition prepared by the process described herein to improve adhesion to polyvinyl chloride substrates.

[0018] Surprisingly, it has been found that a one-component translucent room temperature vulcanizable (RTV) silicone composition comprising a chain extended alkoxy endblocked polydiorganosiloxane polymer, when chain extended with a diacetamido silane chain extender, unexpectedly provides significant improvement in adhesion to traditionally difficult to adhere polyvinyl chloride (PVC) while avoiding known problems previously encountered during attempts to improve translucent sealant adhesion, such as yellowing that can be caused by increasing the concentration of adhesion promoters and / or coloration of the sealant due to the increased presence of titanates.

[0019] The silanol-terminated polydiorganosiloxane (ai) has at least two silanol groups per molecule and may have the formula: (HO) 3-n R n Si-(Z) d -(O) q -(R y SiO (4-y) / 2 ) z -(SiR 2- Z) d -Si-R n (OH) 3-n (1) wherein each R is an alkyl group, an alkenyl group, or an aryl group; Z is a divalent organic group; d is 0 or 1, q is 0 or 1, and d+q=1; n is 0, 1 or 2, y is 0, 1 or 2, and z is an integer such that the organopolysiloxane polymer (ai) has a viscosity of 1,000 to 100,000 mPa·s at 25° C., alternatively 5,000 to 90,000 mPa·s at 25° C., measured at a shear rate of 20 revolutions per minute using a Brookfield® rotational viscometer equipped with spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa·s). Thus, the suffix z may be an integer from about 200 to about 5000.

[0020] Typically, in the above, d is 0, q is 1, and n is 1 or 2, or n is 2. In such a case, the silanol-terminated polydiorganosiloxane (ai) has the structure: (HO) 3-n R n Si-O-(R y SiO (4-y) / 2 ) z -Si-R n (OH) 3-n Where R, y, and z are as described above, the average value of y is about 2, i.e., the silanol terminated polymer is substantially (i.e., (>) 90% greater than linear, alternatively >97% linear).

[0021] Each R is independently selected from alkyl groups, alternatively alkyl groups having 1 to 10 carbon atoms, alternatively 1 to 6 carbon atoms, alternatively 1 to 4 carbon atoms, or methyl or ethyl groups; alkenyl groups, alternatively alkenyl groups having 2 to 10 carbon atoms, alternatively 2 to 6 carbon atoms, such as vinyl, allyl, and hexenyl groups; aromatic groups, alternatively aromatic groups having 6 to 20 carbon atoms, substituted aliphatic organic groups such as 3,3,3-trifluoropropyl groups, aminoalkyl groups, polyaminoalkyl groups, and / or epoxyalkyl groups.

[0022] Each Z is independently selected from an alkylene group having 1 to 10 carbon atoms. In one alternative, each Z is independently selected from an alkylene group having 2 to 6 carbon atoms, and in a further alternative, each Z is independently selected from an alkylene group having 2 to 4 carbon atoms. Each alkylene group may be individually selected, for example, from an ethylene group, a propylene group, a butylene group, a pentylene group, and / or a hexylene group. However, as indicated above, in the present case, d is typically 0 (zero).

[0023] The silanol-terminated polydiorganosiloxane (ai) may be a single siloxane represented by formula (1) or may be a mixture of polydiorganosiloxane polymers represented by the above formula. Thus, the term "siloxane polymer mixture" with respect to the silanol-terminated polydiorganosiloxane (ai) is meant to include any individual polydiorganosiloxane polymer (ai) or a mixture of polydiorganosiloxane polymers (ai).

[0024] The Degree of Polymerization (DP) (i.e., z in the above formula) is usually defined as the number of monomer units in a silicone macromolecule or polymer or oligomer molecule. Synthetic polymers essentially consist of a mixture of macromolecular species with different degrees of polymerization and therefore different molecular weights. There are different types of average polymer molecular weights, which can be measured in different experiments. The two most important are the number average molecular weight (Mn) and the weight average molecular weight (Mw). The Mn and Mw of a silicone polymer can be measured by gel permeation chromatography (GPC) with an accuracy of about 10-15%. This technique is standard and gives the Mw, Mn, and polydispersity index (PI). The Degree of Polymerization (DP) = Mn / Mu, where Mn is the number average molecular weight from the GPC measurement and Mu is the molecular weight of the monomer units. PI = Mw / Mn. DP is related to the viscosity of the polymer by Mw, the higher the DP the higher the viscosity.

[0025] In step (i) of the process, the silanol terminated polydiorganosiloxane (ai) described above is chain extended using at least one diacetamidosilane chain extender (aii). Such diacetamidosilanes (aii) are known chain extender materials for low modulus sealant formulations, for example, as described in U.S. Pat. Nos. 5,017,628 and 3,996,184. Diacetamidosilane chain extenders (aii) are, for example, of the structure CH3-C(=O)-N(R13 )-Si(R 14 )2-N(R 13 )-C(=O)-CH3 wherein each R 13 may be the same or different and may be the same as R as defined above, or each R 13 may be the same or different and may include alkyl groups having 1 to 6 carbons, alternatively 1 to 4 carbons. 14 may also be the same or different and may be the same as R as defined above, but is preferably an alkyl group having 1 to 6 carbons, alternatively 1 to 4 carbons, or an alkenyl group having 2 to 6 carbons, alternatively 2 to 4 carbons, or vinyl. In use, the diacetamido silane chain extender may be selected from one or more of the following: N,N'-(Dimethylsilylene)bis[N-methylacetamide] N,N'-(Dimethylsilylene)bis[N-ethylacetamide] N,N'-(Diethylsilylene)bis[N-methylacetamide] N,N'-(Diethylsilylene)bis[N-ethylacetamide] N,N'-(Dimethylsilylene)bis[N-propylacetamide] N,N'-(Diethylsilylene)bis[N-propylacetamide] N,N'-(dipropylsilylene)bis[N-methylacetamide] N,N'-(dipropylsilylene)bis[N-ethylacetamide] N,N'-(Methylvinylsilylene)bis[N-ethylacetamide] N,N'-(Ethylvinylsilylene)bis[N-ethylacetamide] N,N'-(propylvinylsilylene)bis[N-ethylacetamide] N,N'-(Methylvinylsilylene)bis[N-methylacetamide] N,N'-(ethylvinylsilylene)bis[N-methylacetamide], and / or N,N'-(propylvinylsilylene)bis[N-methylacetamide].

[0026] In the alternative, the diacetamidosilane chain extender can be a dialkyldiacetamidosilane selected from N,N'-(dimethylsilylene)bis[N-ethylacetamide] and / or N,N'-(dimethylsilylene)bis[N-methylacetamide]. Alternatively, the dialkyldiacetamidosilane is N,N'-(dimethylsilylene)bis[N-ethylacetamide].

[0027] The diacetamido silane chain extender (aii) is present in step (i) in an amount from 0.01 to 5% by weight of the composition, alternatively from 0.01 to 3% by weight of the composition, alternatively from 0.01 to 2.5% by weight of the composition, alternatively from 0.05 to 1% by weight of the composition.

[0028] The chain extended silanol terminated polydiorganosiloxane intermediate (aiii) is prepared in step (i) by mixing and reacting the silanol terminated polydiorganosiloxane (ai) with the diacetamidosilane chain extender (aii) at room temperature or at a temperature between 20° C. and 40° C. for 5 to 20 minutes or until minimal residual diacetamidosilane chain extender (aii) can be detected in the resulting mixture. Mixing can be carried out in any suitable type of mixer, such as a Speedmixer or a Turello mixer.

[0029] If desired, a suitable plasticizer / extender, hereafter referred to as a plasticizer (sometimes identified as a processing aid), can be introduced to the product of step (i) containing the chain-extended silanol terminated polydiorganosiloxane intermediate (aiii) prior to step (ii) because the chain extension process of step (i) significantly increases the viscosity of the polymer undergoing chain extension, and the introduction of a plasticizer, if desired, reduces the viscosity of the chain-extended silanol terminated polydiorganosiloxane intermediate (aiii) prior to step (ii), the endcapping step described below.

[0030] Once it has been determined that step (i) is complete, step (ii) may proceed, in which the chain-extended silanol-terminated polydiorganosiloxane intermediate (aiii) is alkoxy endcapped by reaction with one or more polyalkoxysilanes (aiv), as defined above, in the presence of a basic endcapping catalyst (av).

[0031] The one or more polyalkoxysilanes (aiv) have the structure (R 2 -O) (4-b) -Si-R 1 b (wherein b is 0, 1, or 2, or 0 or 1; R 2 is an alkyl group having 1 to 15 carbons, 1 to 10 carbons, or 1 to 6 carbons, which may be linear or branched, for example, methyl, ethyl, propyl, n-butyl, t-butyl, pentyl, and hexyl, or may be methyl or ethyl, or R 2 R may be a methyl group) with one or more polyalkoxysilane starting materials. 1 R may be substituted by any suitable group, i.e., substituted or unsubstituted, e.g., halogens such as fluorine and chlorine. 2 monovalent hydrocarbon radicals such as, for example, trifluoropropyl and / or perfluoropropyl; cycloalkyl groups (e.g., cyclopentyl and cyclohexyl); alkenyl groups (e.g., vinyl and allyl); aryl groups (e.g., phenyl and tolyl); aralkyl groups (e.g., 2-phenylethyl); and groups obtained by replacing all or part of the hydrogens in the aforementioned organic groups with halogens. In one embodiment, R 1can be vinyl, methyl, or ethyl, or vinyl or methyl, or methyl. When b is 0 or 1, this means that the polyalkoxysilane has 4 or 3 alkoxy groups. Typically, silanol-terminated polydiorganosiloxanes (ai) have one terminal silanol bond (-Si-OH) per terminal silicon, and in such cases, the endcapping reaction produces an end group, such as alkyl or vinyl, that replaces the (-Si-OH) with 3 Si-alkoxy bonds or 2 Si-alkoxy bonds.

[0032] Typically, the amount of polyalkoxysilane (aiv) present in the starting material for the endcapping reaction is determined so that there is at least an equimolar amount of polyalkoxysilane relative to the amount of -OH groups on the polymer. Thus, the higher the viscosity / chain length of the intermediate (aiii) used, the lower the number of -OH groups present in the polymer, and therefore less polyalkoxysilane (aiv) is required. Similarly, the reverse is also true, i.e., the lower the viscosity / chain length of the intermediate (aiii) used, the higher the number of -OH groups present in the intermediate (aiii), and therefore more polyalkoxysilane (aiv) is required. However, in some cases, it is preferred to include a significant molar excess of polyalkoxysilane (aiv), so that any residual unreacted polyalkoxysilane (aiv) present at the end of the endcapping reaction, i.e., in the alkoxy endcapping polydiorganosiloxane polymer reaction end product, is then utilized as a crosslinker in the one-component translucent room temperature vulcanizable (RTV) silicone composition. Thus, in one embodiment herein, there is preferably a molar excess of polyalkoxysilane (aiv) relative to the --OH groups on the intermediate (aiii) to be endcapped.

[0033] The endcapping catalyst (av) utilized according to the disclosure of this specification may be any suitable basic catalyst that catalyzes the alkoxy endcapping reaction.Such suitable basic catalysts include, for example, tetramethylammonium amine hydroxide, basic inorganic oxides, titanium / amine combinations, carboxylic acid / amine combinations, N,N'-disubstituted hydroxylamines, carbamates, metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and oxime-containing organic compounds.However, one particularly preferred group of basic catalysts is one or more linear, branched or cyclic molecules containing one or more groups selected from amidine groups, guanidine groups, derivatives of amidine groups and / or guanidine groups, or mixtures thereof.

[0034] The amidine or guanidine group may comprise a linear, branched, or cyclic silicon-containing molecule or a linear, branched, or cyclic organic molecule containing one or more of the groups / structures (1)-(4) shown below.

[0035] [ka] In the formula, each R 4 , R 5 , R 6 , R 7 and R 8 may be the same or different and may be selected from hydrogen, an alkyl group, a cycloalkyl group, a phenyl group, an aralkyl group, or alternatively, R 4 and R 5 , or R 6 and R 5 , or R 7 and R 5 , or R 8 and R 4 may optionally form a ring structure, for example, they may form a heterogeneously substituted alkylene group to create a ring structure, the heterogeneous substitution being with an oxygen or nitrogen atom.

[0036] In one embodiment, groups / structures (1)-(4) can be part of a silane structure in which the nitrogen is bonded to the silicon atom via an alkylene group, for example: (R 10 )3Si-ZA where Z is as previously described and each R 10 can be the same or different and can be hydroxyl groups and / or hydrolyzable groups (such as those described in connection with crosslinker (c) later in this specification), alkyl groups, cycloalkyl groups, alkenyl groups, aryl groups, or aralkyl groups, and A is one of the groups / structures (1)-(4) above.

[0037] In a further alternative, any one of the above groups / structures (1)-(4) may be attached to a polymer radical selected from the group consisting of alkyd resins, oil-modified alkyd resins, saturated or unsaturated polyesters, natural oils, epoxides, polyamides, polycarbonates, polyethylene, polypropylene, polybutylene, polystyrene, ethylene-propylene copolymers, (meth)acrylates, (meth)acrylamides and their salts, phenolic resins, polyoxymethylene homopolymers and copolymers, polyurethanes, polysulfones, polysulfide rubbers, nitrocellulose, vinyl butyrate, vinyl polymers, ethyl cellulose, cellulose acetate and / or butyrate, rayon, shellac, waxes, ethylene copolymers, organic rubbers, polysiloxanes, polyether siloxanes, silicone resins, polyethers, polyether esters and / or polyether carbonates. When the groups / structures (1) to (4) are bonded to a siloxane radical, they may be bonded to a polysiloxane radical having an average molecular weight in the range of 206 to 50,000 g / mol, in particular 280 to 25,000 g / mol, particularly preferably 354 to 15,000 g / mol. Endblocking catalysts having such polysiloxane radicals are typically liquid at room temperature, have low vapor pressure, are particularly easily compatible in curable compositions based on silicone polymers, and in this connection are particularly prone to little separation or migration.

[0038] For example, the endcapping catalyst (av) can be 1,1,3,3-tetramethylguanidine (TMG), which has the structure (CH3)2N-C=NH(N(CH3)2), or it can be a silane of the following structure: (R 2 -O) (4-a-b) -Si-R 3 a R 1 b In the formula, R 2 , R 1 , and b are as described above, a is 1, and R 3 is Z 1 -N=C-(NR 5 R 4 )2, In the formula, R 5 and R 4 is as defined above, and Z 1 is an alkylene or oxyalkylene group having 2 to 6 carbons, and a is 1.

[0039] Specific examples include 2-[3-(trimethoxysilyl)propyl]-1,1,3,3-tetramethylguanidine and 2-[3-(methyldimethoxysilyl)propyl]-1,1,3,3-tetramethylguanidine.

[0040] Alternatively, the endcapping catalyst (av) can be, for example, Triazabicyclodecene (1,5,7-triazabicyclo[4.4.0]dec-5-ene, TBD), as shown below, or

[0041] [ka] It may be a cyclic guanidine such as 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (mTBD) shown below.

[0042] [ka]

[0043] Alternatively, the end-capping catalyst (av) may be, for example, 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) shown below:

[0044] [ka] Or it may be a cyclic amidine such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) shown below.

[0045] [ka]

[0046] If step (ii) of the process can be continuously mixed (e.g., using a magnetic stir bar or overhead mechanical stirrer), the endcapping catalyst (av) can be added directly as a solid. Furthermore, if the endcapping catalyst (av) can be introduced to the reaction environment in the form of a fine powder, a solvent is optional. If the reaction components are mixed and allowed to settle, the endcapping catalyst (av) can be delivered as a solution to ensure uniform dispersion. If delivered in a solution, the solvent can be a compatible silicone or organic solvent, such as, for example, trimethyl-terminated polydimethylsiloxane or toluene. However, in order to minimize VOC issues, it has been found that the preferred liquid for delivery of the endcapping catalyst is in fact the polyalkoxysilane (aiv) utilized to endcapping the silanol-terminated polydiorganosiloxane intermediate (aiii), or one of them, such as vinyltrimethoxysilane and / or methyltrimethoxysilane.

[0047] If desired, the endcapping catalyst (av) used, i.e. one or more linear, branched or cyclic molecules containing one or more groups selected from amidine groups, guanidine groups, derivatives of said amidine groups and / or guanidine groups, or mixtures thereof, may remain in the alkoxy end-capped polymer reaction end product. Alternatively, depending on its physical properties, the endcapping catalyst (av) may be extracted from the polymer reaction end product after completion of the reaction, if it is worth and / or desired. Catalyst extraction may be carried out at the end of the reaction process, if necessary, before or after the optional introduction of a neutralizing / stabilizing agent. The extraction method selected depends on the physical properties of the endcapping catalyst, for example by filtration or optionally by vacuum distillation.

[0048] If step (ii) is performed, it is based on the weight of the final mixture in the absence of a subsequent additional step (e.g., to make a one-component translucent room temperature vulcanizable (RTV) silicone composition or similar composition): (aiii) a chain extended silanol terminated polydiorganosiloxane intermediate in an amount of from 40% by weight to 99.5% by weight of the component, alternatively from 60% by weight to 99.5% by weight of the component in step (ii), alternatively from 70% by weight to 99.5% by weight of the component in step (ii), alternatively from 80% by weight to 99.5% by weight of the component in step (ii), alternatively from 90% by weight to 99.5% by weight of the component in step (ii), alternatively from 95% by weight to 99.5% by weight of the component in step (ii); (aiv) Structure: (R 2 -O) (4-b) -Si-R 1 b (wherein b is 0, 1 or 2; R 2 is an alkyl group having 1 to 15 carbons, which may be linear or branched; R 1 may be any suitable group, i.e. R 2cycloalkyl groups; alkenyl groups, aryl groups; aralkyl groups, and groups obtained by substituting all or a portion of the hydrogens in the preceding organic radicals with halogens, and may be present in an amount of about 0.5 to 60% by weight of the step (ii) components, alternatively 0.5 to 40% by weight of the step (ii) components, alternatively 0.5 to 30% by weight of the step (ii) components, alternatively 0.5 to 20% by weight of the step (ii) components, alternatively 0.5 to 10% by weight of the step (ii) components, alternatively 0.5 to 5% by weight of the step (ii) components, and alternatively 0.25 to 2.5% by weight of the step (ii) components; (av) an endcapping catalyst in the form of any suitable basic catalyst that catalyzes the alkoxy endcapping reaction, such as, for example, tetramethylammonium amine hydroxide, basic inorganic oxides, titanium / amine combinations, carboxylic acid / amine combinations, N,N'-disubstituted hydroxylamines, carbamates, metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and oxime-containing organic compounds, but preferably consisting of one or more linear, branched or cyclic molecules containing at least one amidine group, guanidine group, or derivatives of said amidine and / or guanidine groups, or mixtures thereof.

[0049] The endcapping catalyst (av) may be introduced in any suitable amount depending on the catalyst selected for use. In the case of the preferred one or more linear, branched or cyclic molecules containing at least one amidine group, guanidine group, or derivatives of said amidine and / or guanidine groups, or mixtures thereof, the catalyst is provided in an amount of 0.0005 to 0.75% by weight of the step (ii) components.

[0050] It should be remembered that, if desired, one or more polyalkoxysilanes (aiv) may be provided in large excess amounts for reasons explained elsewhere. If the plasticizer is added prior to the start of step (ii) above, component (aiii) is a mixture of the chain-extended silanol-terminated polydiorganosiloxane intermediate (aiii) and the plasticizer.

[0051] In one embodiment, the chain-extended silanol-terminated polydiorganosiloxane intermediate (aiii) is typically introduced into a suitable mixer and stirred, then one or more polyalkoxysilanes (aiv) are added and the resulting mixture is mixed again. Any suitable mixing time may be used for step (ii), such as from 10 to 30 minutes, alternatively from 10 to 20 minutes.

[0052] Optionally, the mixing in step (ii) may be carried out at an elevated temperature up to about 100° C., for example, from 35 to 100° C., alternatively from 50 to 80° C. An endcapping catalyst may be introduced, if deemed necessary, before, simultaneously with, or after the addition of one or more polyalkoxysilanes.

[0053] The resulting product of step (ii) can be isolated from by-products and endblocking catalysts, etc., if desired. Alternatively, equimolar amounts of intermediate (aiii) and polyalkoxysilane (aiv) can be utilized in the reaction process, such that there is no excess of polyalkoxysilane (aiv), but likewise, if desired, excess polyalkoxysilane (aiv) can be added to the reaction mixture, and any excess polyalkoxysilane (aiv) is intended to be utilized as crosslinker (c) or as a portion of crosslinker (c) in the preparation of a one-component translucent room temperature vulcanizable (RTV) silicone composition.

[0054] As mentioned above, a plasticizer may be introduced. Typically, this is done after step (i) and before step (ii), but if preferred, it may be added after step (ii) or during or after step (iii). The plasticizer selected may be any of the plasticizers specified in GB Patent No. 2445821, which is incorporated herein by reference.

[0055] Examples of plasticizers include non-reactive linear siloxanes such as trialkyl terminated polydiorganosiloxanes, e.g., trimethyl terminated polydimethylsiloxane, e.g., hexamethyldisiloxane, octamethyltrisiloxane, and other short chain linear siloxanes such as octamethyltrisiloxane, decamethyltetrasiloxane, dodecamethylpentasiloxane, tetradecamethylhexasiloxane, hexadecamethylhept ... cyclosiloxane, heptamethyl-3-{(trimethylsilyl)oxy}trisiloxane, cyclic siloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane; optionally further polydiorganosiloxanes, including aryl-functional siloxanes, having a viscosity of 0.5 to 12,500 mPa·s measured at 25° C. using a glass capillary viscometer (ASTM D-445, IP 71) for 0.5 to 5000 mPa·s (5000 mPa·s requires testing at 100° C.). For 5000 to 12500 mPa.s, a Brookfield cone-plate viscometer RV DIII with cone-plate CP-52 at 5 rpm is used (ASTM D4287).

[0056] Alternatively, the plasticizer may include an organic liquid such as butyl acetate, an alkane, an alcohol, a ketone, an ester, an ether, a glycol, a glycol ether, a hydrocarbon, a hydrofluorocarbon, or any other material capable of diluting the composition without adversely affecting any of the component materials. Hydrocarbons include isododecane, isohexadecane, Isopar™ L (C11-C13), Isopar™ H (C11-C12), hydrogenated polydecene, mineral oil, especially hydrogenated mineral oil or white oil, liquid polyisobutene, isoparaffinic oil, or petroleum jelly. Ethers and esters include isodecyl neopentanoate, neopentyl glycol heptanoate, glycol distearate, dicaprylyl carbonate, diethylhexyl carbonate, propylene glycol n-butyl ether, ethyl-3-ethoxypropionate, propylene glycol methyl ether acetate, tridecyl neopentanoate, propylene glycol methyl ether acetate (PGMEA), propylene glycol methyl ether (PGME), octyldodecyl neopentanoate, diisobutyl adipate, diisopropyl adipate, propylene glycol dicaprylate / dicaprate and octyl palmitate.Preferably, when present, plasticizer comprises or consists of one or more of the above-mentioned silicon-containing liquids.

[0057] If desired, an acidic stabilizer / neutralizer can be added to the chain-extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a) upon completion of the endblocking reaction in step (ii). This can be done immediately after step (ii) or during the preparation of the one-component translucent room temperature vulcanizable (RTV) silicone composition, for example after the introduction of a filler. The chain-extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a) can be stabilized by the addition of an acidic stabilizer / neutralizer such that the one-component translucent room temperature vulcanizable (RTV) silicone composition obtained upon preparation can be obtained.

[0058] The resulting chain extended, alkoxy endblocked polydiorganosiloxane polymer (a) may be recovered and stored for future use (in which case the neutralization step, if performed, occurs immediately or shortly after completion of step (ii) of the present process), or the resulting chain extended, alkoxy endblocked polydiorganosiloxane polymer (a) may be used immediately, in which case it may be used as an additional component of the one-component translucent room temperature vulcanizable (RTV) silicone composition, namely: (b) optionally a crosslinker; (c) a reinforcing silica filler, which may optionally be hydrophobically treated; and (d) one or more moisture scavengers; and (e) one or more adhesion promoters; (f) Tin-based catalysts are: They may be introduced into the composition in any suitable order.

[0059] In one embodiment, components (b), (c), (d), (e), and (f) may be introduced sequentially in alphabetical order to the chain extended alkoxy endblocked polydiorganosiloxane polymer (a) with mixing between each introduction. In an alternative embodiment, components (f), (b), and (e) are mixed together with component (a), followed by introduction of component (c) and further mixing of the resulting mixture to allow chemically available residual -OH groups on the polymer and / or filler to condense with the crosslinker and / or optional adhesion promoter to produce alcohol by-products which are then removed by vacuum stripping at a predetermined controlled temperature between 50°C and 100°C, followed by addition of component (d).

[0060] Alternatively, the first component added to the chain-extended alkoxy endblocked polydiorganosiloxane polymer (a) may be, for example, the filler (c) to effectively form a base comprising the chain-extended alkoxy endblocked polydiorganosiloxane (a) and the filler (c). The other components may then be added in any preferred order of addition, for example, additional crosslinker (b) if desired, followed by curing catalyst (f), followed by adhesion promoter (e) if desired, followed by other optional additional components if desired. Alternatively, the adhesion promoter (e), crosslinker (b), if desired, and tin-based catalyst (f) may be added first, followed by the filler (s), and finally the stabilizer / scavenger (d).

[0061] The chain-extended alkoxy-terminated polydiorganosiloxane polymer (a) is incorporated into a one-component translucent room temperature vulcanizable (RTV) silicone composition. By room temperature vulcanizable composition, it is meant that the composition cures at room temperature without the need for heating, although curing may be accelerated by heating if deemed appropriate.

[0062] The reaction product of step (ii), the chain extended alkoxy endblocked polydiorganosiloxane reaction product (a), is typically present in the one-component translucent RTV silicone composition in an amount of from 40 to 90% by weight of the composition, alternatively from 40 to 80% by weight of the composition, alternatively from about 40 to 65% by weight of the one-component translucent RTV silicone composition.

[0063] The one-component translucent room temperature vulcanizable (RTV) silicone compositions described above can be designed to form products upon cure that have a low modulus.

[0064] The separate addition of crosslinker (b) to the one-component translucent room temperature vulcanizable (RTV) silicone composition is optional because crosslinker (b) is an essential component in the one-component translucent room temperature vulcanizable (RTV) silicone composition, but is not included in the structure used in the endcapping reaction described above. (R 2 -O) (4-b) -Si-R 1 b (In the formula, R 2 , R 1 and b may be the same as one or more of the polyalkoxysilanes of (a) and (b) as described above. In this case, as described above, it is possible to introduce a sufficient excess of polyalkoxysilane into the reaction mixture for endcapping the chain-extended silanol-terminated polydiorganosiloxane intermediate during the endcapping reaction in the subsequent preparation of a one-component translucent room temperature vulcanizable (RTV) silicone composition, such that no additional crosslinker (b) is required. However, additional crosslinker (b) may be added during the preparation of the one-part alkoxy-functional silicone sealant composition, if deemed necessary.

[0065] When an amount of crosslinker (b) is added during the preparation of the one-component translucent room temperature vulcanizable (RTV) silicone composition, any suitable crosslinker having at least three groups per molecule that can react with the hydroxyl or hydrolyzable groups of the chain-extended alkoxy endblocked polydiorganosiloxane polymer (a) can be utilized.Typically, the optional crosslinker (b) added includes one or more silanes or siloxanes containing silicon-bonded hydrolyzable groups, such as acyloxy groups (e.g., acetoxy, octanoyloxy, and benzoyloxy groups); ketoximino groups (e.g., dimethyl ketoximo groups and isobutylketoximino groups); alkoxy groups (e.g., methoxy, ethoxy, isobutoxy, and propoxy), and alkenyloxy groups (e.g., isopropenyloxy and 1-ethyl-2-methylvinyloxy).

[0066] Crosslinker (b) must have at least three or four hydroxyl and / or hydrolyzable groups per molecule, which are reactive with the alkoxy groups of the chain-extended alkoxy-endblocked polydiorganosiloxane polymer (a).When crosslinker (b) is required to be added during the preparation of one-component translucent room temperature vulcanizable (RTV) silicone composition, crosslinker (b) is a silane, and when the silane has a total of three silicon-bonded hydroxyl and / or hydrolyzable groups per molecule, the fourth group is preferably a non-hydrolyzable silicon-bonded organic group.These silicon-bonded organic groups are preferably hydrocarbyl groups optionally substituted with halogens such as fluorine and chlorine. Examples of such fourth groups include alkyl groups (e.g., methyl, ethyl, propyl, and butyl); cycloalkyl groups (e.g., cyclopentyl and cyclohexyl); alkenyl groups (e.g., vinyl and allyl); aryl groups (e.g., phenyl and tolyl); aralkyl groups (e.g., 2-phenylethyl); and groups obtained by replacing all or part of the hydrogens in the aforementioned organic groups with halogens. However, preferably, the fourth silicon-bonded organic group is methyl.

[0067] Silanes that can be used as crosslinking agents (b) include alkyltrialkoxysilanes such as methyltrimethoxysilane (MTM) and methyltriethoxysilane, alkenyltrialkoxysilanes such as vinyltrimethoxysilane and vinyltriethoxysilane, and isobutyltrimethoxysilane (iBTM). Other suitable silanes include ethyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, alkoxytrioximosilane, alkenyltrioximosilane, 3,3,3-trifluoropropyltrimethoxysilane, methyltriacetoxysilane, vinyltriacetoxysilane, ethyltriacetoxysilane, di-butoxydiacetoxysilane, phenyl-tripropionoxysilane, methyltris(methylethylketoximo)silane, vinyl-tris-methylethylketoximo)silane, methyltris(methylethylketoximino)silane, methyltris(isopropenoxy)silane, vinyltris(isopropenoxy)silane, ethylpolysilicate, n-propylorthosilicate, and ethylorthosilicate. The crosslinker (b) may alternatively comprise any combination of two or more of the above. In one embodiment, the crosslinker may be one or more of vinyltrimethoxysilane, methyltrimethoxysilane, and / or vinylmethyldimethoxysilane.

[0068] The composition suitably contains at least a stoichiometric amount of crosslinker (b) relative to the chain extended alkoxy endblocked polydiorganosiloxane polymer (a) described above, whether it results from the endblocking reaction as an excess, or from its addition after completion of the endblocking reaction, or a combination of the two. Thus, the amount present will also depend on the specific nature of the crosslinker (b) utilized, particularly the molecular weight of the molecule selected. Thus, the crosslinker is typically present in the composition in an amount of 0.1-5% by weight of the composition, but may potentially be present in greater amounts.

[0069] The reinforcing silica filler (c) may contain one or more finely divided reinforcing silica fillers such as fumed silica, colloidal silica and / or precipitated silica. Typically, the filler has a surface area of ​​75 to 400 m. 2 / g (measured using the BET method according to ISO 9277:2010) or 100-300m 2 / g (measured using the BET method according to ISO 9277:2010).

[0070] Typically, the filler (c) is present in the composition in an amount of about 5-30% by weight of the composition, alternatively about 5-25% by weight of the composition, alternatively about 5-15% by weight of the composition, depending on the filler selected. If silica is used as a neutralizer / stabilizer in the process involving the endcapping catalyst (av), it will be understood that the amount of silica present is cumulative, since any silica filler added as a neutralizer / stabilizer contributes to the filler content of the one-component translucent room temperature vulcanizable (RTV) silicone composition. Thus, if 2.5% by weight of silica is used in step (ii) as a neutralizer / stabilizer, the total amount of filler in the one-component translucent room temperature vulcanizable (RTV) silicone composition will be 2.5% by weight more than the amount of filler added to the composition if introduced separately.

[0071] The filler (c) may be hydrophobically treated, for example with one or more fatty acids, for example fatty acids such as stearic acid or fatty acid esters such as stearates, or with organosilanes, polydiorganosiloxanes or organosilazane hexaalkyldisilazanes, or short chain siloxane diols, to render the filler (c) hydrophobic and thus easier to process and obtain a homogeneous mixture with the other adhesive components. The surface treatment of the filler makes it easier to be wetted with the chain-extended alkoxy endblocked polydiorganosiloxane polymer (a). These surface-modified fillers do not aggregate and can be homogeneously incorporated into the chain-extended alkoxy endblocked polydiorganosiloxane polymer (a). This results in improved mechanical properties at room temperature of the uncured composition. The filler may be pretreated or may be treated in situ when mixed with the chain-extended alkoxy endblocked polydiorganosiloxane polymer (a). In order to make the resulting sealant translucent, other fillers such as calcium carbonate cannot be utilized as the resulting sealant would become opaque.

[0072] Component (d) is a moisture scavenger or -OH scavenger (i.e. moisture / water / alcohol). They are typically silazane or silane compounds used as crosslinkers. Any suitable -OH (moisture / water / alcohol) scavenger may be used, such as orthoformates, molecular sieves, silazanes such as organosilazanes, hexaalkyldisilazanes such as hexamethyldisilazane, and / or one or more silanes of the following structures: R 20 j Si(OR 21 ) 4-j (In the formula, each R 21 may be the same or different and are alkyl groups having at least 2 carbon atoms; j is 1 or 0; R 20is a substituted or unsubstituted, linear or branched monovalent hydrocarbon group having at least two carbons, a cycloalkyl group, an aryl group, an aralkyl group, or a silicon-bonded organic group selected from any one of the foregoing, in which at least one hydrogen atom bonded to a carbon is replaced by a halogen atom, or an organic group having an epoxy group, a glycidyl group, an acyl group, a carboxyl group, an ester group, an amino group, an amide group, a (meth)acrylic group, a mercapto group, or an isocyanate group. One or more of the silanes may be used in the condensation curable organosiloxane composition as needed. If present, the -OH scavenger is typically present in the range of 0.5 to 3.0 weight percent of the total composition, but the amount may be more dependent on the amount of alcohol by-products produced and the process used to produce the composition. Scavenged by-products are intentionally removed, where possible, from the final one-component translucent room temperature vulcanizable (RTV) silicone composition to achieve stability and prevent reversion during storage.

[0073] Component (e) is an adhesion promoter, and suitable adhesion promoters (e) are represented by the formula R 14 h Si(OR 15 ) (4-h) where subscript h is 1, 2, or 3, or h is 3. 14 R is independently a monovalent organic functional group. 14 can be an epoxy functional group such as glycidoxypropyl or (epoxycyclohexyl)ethyl; an amino functional group such as aminoethylaminopropyl or aminopropyl; methacryloxypropyl; a mercapto functional group such as mercaptopropyl, or an unsaturated organic group. 15 R is independently an unsubstituted saturated hydrocarbon group having at least one carbon atom. 15 R may have 1 to 4 carbon atoms, alternatively 1 to 2 carbon atoms. 15Examples of alkoxysilanes include methyl, ethyl, n-propyl, and isopropyl.

[0074] Alternatively, the adhesion promoter may be glycidoxypropyltrimethoxysilane or a multifunctional material obtained by reacting two or more of the above, such as the reaction product of an alkylalkoxysilicone, such as trimethoxymethylsilane; an aminoalkoxysilane, such as 3-aminopropyltrimethoxysilane, with an epoxyalkoxysilane, such as glycidoxypropyltrimethoxysilane, in a weight ratio of (i):(ii):(iii) of 0.1-6:0.1-5:1.

[0075] Examples of suitable adhesion promoters (e) also include those having the structure: (R'O)3Si(CH2) g N(H)-(CH2) q NH2 wherein each R' may be the same or different and is an alkyl group having 1 to 10 carbon atoms, g is 2 to 10, and q is 2 to 10. It may also include molecules of

[0076] The one-component translucent room temperature vulcanizable (RTV) silicone composition may comprise from 0.01 to 2 weight percent, alternatively from 0.05 to 2 weight percent, alternatively from 0.1 to 1 weight percent of an adhesion promoter, based on the weight of the composition. Preferably, the hydrolysis rate of the adhesion promoter should be slower than the hydrolysis rate of the crosslinker, to favor diffusion of the molecules into the substrate rather than incorporation into the product network.

[0077] The one-component translucent room temperature vulcanizable (RTV) silicone composition also includes a condensation cure tin-based catalyst (f). Any suitable tin catalyst may be utilized. The tin catalyst (f) may be any of the following organotin metal catalysts: tin triflate, triethyltin tartrate, tin octoate, tin oleate, tin naphthenate, butyltin tri-2-ethylhexanoate, tin butyrate, carbomethoxyphenyltin trisperate, and isobutyltin triceroate; and diorganotin salts, in particular, dibutyltin dilaurate (DBTDL), dioctyltin dilaurate (DOTDL), dimethyltin dibutyrate, dibutyltin dimethoxide, dibutyltin diacetate (DBTDA), dibutyltin dibenzoate, stannous octoate, dibutyltin bis(2,4-pentanedionate), and dimethyltin dineodecanoate. The additives may include one or more of diorganotin dicarboxylate compounds such as dioctyltin dineodecanoate (DMTDN), dioctyltin dineodecanoate (DOTDN), and dibutyltin dioctoate.

[0078] The condensation cure tin-based catalyst (f) is typically present in the composition in an amount from 0.25 to 4.0% by weight of the one-component translucent room temperature vulcanizable (RTV) silicone composition, alternatively from 0.25 to 3% by weight of the composition, alternatively from 0.3% to 2.5% by weight of the composition.

[0079] If necessary, other additives may be used in the one-component translucent room temperature vulcanizable (RTV) silicone composition. These may include rheology modifiers, stabilizers, such as antioxidants, UV and / or light stabilizers, pigments, and bactericides and / or biocides. It is understood that some of the additives are listed in multiple additive lists. In that case, such additives have the ability to function in all the different applications mentioned.

[0080] Rheology modifiers that can be incorporated into the moisture-curable compositions according to the invention include silicone organic copolymers, such as those described in EP 0802233, based on polyether or polyester polyols; waxes, such as polyamide waxes; non-ionic surfactants selected from the group consisting of polyethylene glycols, polypropylene glycols, ethoxylated castor oil, oleic acid ethoxylates, alkylphenol ethoxylates, copolymers or ethylene oxide and propylene oxide, and silicone polyether copolymers; silicone glycols. For some systems, these rheology modifiers, especially the copolymers of ethylene oxide and propylene oxide, and silicone polyether copolymers, can enhance adhesion to substrates, especially plastic substrates.

[0081] Any suitable antioxidant may be utilized if deemed necessary. Examples include ethylene bis(oxyethylene) bis(3-tert-butyl-4-hydroxy-5(methylhydrocinnamate), 36443-68-2; tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, 6683-19-8; octadecyl[3,5-di-tert-butyl-4-hydroxyhydroxycinnamate, 2082-79-3; N,N'-hexamethylene-bis(3,5 3,5-Di-tert-butyl-4-hydroxyhydrocinnamic acid, C7-9 branched alkyl esters, 125643-61-0; N-phenylbenzenamine, reaction products with 2,4,4-trimethylpentene, 68411-46-1; Mention may be made, for example, of the antioxidants sold under the name Irganox® by BASF.

[0082] UV and / or light stabilizers may include, for example, benzotriazole-based ultraviolet absorbers and / or hindered amine light stabilizers (HALS), such as the TINUVIN® line of products from Ciba Specialty Chemicals Inc.

[0083] If necessary, a biocide can further be used in the composition. It should be noted that the term "biocide" is intended to include bactericides, fungicides, algaecides, and the like.

[0084] Generally, the chain-extended alkoxy endblocked polydiorganosiloxane polymer (a) is prepared as described above, which is at least partially completed before the addition of other components of the one-component translucent room temperature vulcanizable (RTV) silicone composition.Typically, the endblocking reaction is completed before the addition of other components of the one-component translucent room temperature vulcanizable (RTV) silicone composition, and if desired, an acid stabilizer / neutralizer is added and the endblocking catalyst is removed.If desired, additional components of the one-component translucent room temperature vulcanizable (RTV) silicone composition may be introduced immediately after the endblocking process (including the introduction of the acid stabilizer / neutralizer, which is added if desired, and the removal of the endblocking catalyst) is completed.

[0085] The one-component translucent room temperature vulcanizable (RTV) silicone compositions prepared by the processes described herein can be designed to provide low modulus and high elongation sealant, adhesive, and / or coating compositions designed for adhesion onto PVC substrates. The low modulus silicone sealant compositions are preferably "gunnable", i.e., have a suitable extrusion capacity, i.e., minimum extrusion rate, as measured by ASTM C1183-04, of 10 ml / min, alternatively 10-1000 mL / min, alternatively 100-1000 mL / min.

[0086] The components and their amounts in the one-component translucent room temperature vulcanizable (RTV) silicone composition can be selected to impart migration capability to the sealant material after curing, where the migration capability can be greater than 25%, or the migration capability can range from 25% to 50%, as measured by ASTM C719-13.

[0087] The one-component translucent room temperature vulcanizable (RTV) silicone composition as described above may be a gun-applicable sealant composition used in space / void applications; sealing applications such as sealing the edges of lap joints in construction membranes; or sealing penetration applications, e.g., sealing vents in construction membranes; and bonding at least two substrates together.

[0088] The one-component translucent room temperature vulcanizable (RTV) silicone compositions prepared herein are particularly provided for adhesion to PVC, while avoiding known problems previously encountered during efforts to improve translucent sealant adhesion, such as yellowing that can be caused by increasing the concentration of adhesion promoters and / or causing coloration of the sealant due to increased presence of titanates.

[0089] As previously mentioned, it is well known in the industry that one-component translucent room temperature vulcanizable (RTV) silicone compositions have historically been known to have poor adhesion properties to polyvinyl chloride (PVC), for example, used in the manufacture of window and door frames. This lack of adhesion problem has heretofore prevented many compositions of this type from being useful for sealing PVC glazing units and the like. Thus, it was entirely unexpected to find a significantly improved adhesion profile for the compositions herein with respect to PVC substrates. The present inventors have unexpectedly identified a one-component translucent room temperature vulcanizable (RTV) silicone composition suitable for sealing PVC substrates, comprising a chain-extended alkoxy endblocked polydiorganosiloxane polymer and a tin-based catalyst, thereby appearing to provide a solution to a long-standing industry problem. This is particularly due to the industry preference for using PVC in multiple glazing units such as windows and doors, and the desire to use low modulus silicone sealants to seal glazing units in buildings and the like, as they can be easily compressed and expanded by building movement such as wind without causing cohesive or adhesive failure.

[0090] 1. A method for filling a space between two substrates, one or both of which are PVC substrates, thereby creating a seal therebetween, comprising: a) providing a one-component translucent room temperature vulcanizable (RTV) silicone composition as described herein above; b) applying a one-component translucent room temperature vulcanizable (RTV) silicone composition to a first substrate and contacting a second substrate with the silicone composition applied to the first substrate; or c) filling a space formed by the arrangement of the first and second substrates with a one-component translucent room temperature vulcanizable (RTV) silicone composition and curing the composition, wherein the first substrate, the second substrate, or the first and second substrates are made from polyvinyl chloride (PVC).

[0091] In an alternative example, the one-component translucent room temperature vulcanizable (RTV) silicone composition prepared as described herein may be a self-leveling sealant. A self-leveling sealant composition means that when it is extruded from a storage container into a horizontal joint, it is "self-leveling", i.e., the sealant will flow under gravity enough to provide intimate contact between the sealant and the sides of the joint space. This can result in maximum adhesion of the sealant to the joint surface. Self-leveling also eliminates the need to tool the sealant after it is placed into the joint, as required by sealants designed for use in both horizontal and vertical joints. Thus, the sealant flows well enough to fill the crack when applied. If the sealant has sufficient flow under gravity, it will form intimate contact with the sides of the irregular crack walls and form a good bond, but there is no need to tool the sealant after it is extruded into the crack to mechanically apply force to contact the crack sidewalls.

[0092] The self-leveling compositions described herein are useful as sealants with a unique combination of properties required to function as self-leveling sealants. Asphalt paving materials are used to build up significant thicknesses of material, such as 20.32 cm, to form asphalt highways, and to repair deteriorated concrete highways by coating with layers as thick as 10.16 cm. Asphalt coatings are subject to a phenomenon known as reflective cracking, in which cracks form in the asphalt coating due to the movement of the underlying concrete at joints present in the concrete. These reflective cracks must be sealed to prevent water from entering the cracks, which would further destroy the asphalt pavement if the water freezes and expands.

[0093] To form an effective seal for a crack that is subject to movement for any reason, such as thermal expansion and contraction, the sealing material must bond to the interface of the sidewalls of the crack and not lose its bond as the crack compresses and expands. In the case of asphalt pavements, the sealant must not exert enough strain on the asphalt at the interface to cause the asphalt to fracture itself, i.e., the elastic modulus of the sealant must be low enough that the stress applied at the bond line is well below the yield strength of the asphalt.

[0094] In such cases, the modulus of elasticity of the cured material is designed to be low enough so that it does not exert enough force on the asphalt to cause it to cohesively fail. The cured material is such that when placed under tension, the level of stress caused by the tension decreases over time, and the joints are not exposed to high stress levels even at high degrees of elongation.

[0095] Alternatively, the one-component translucent room temperature vulcanizable (RTV) silicone composition produced by the process described herein can be utilized, for example, as a glazing sealant for residential decoration, and / or as an elastomeric coating composition, for example, as a barrier coating for building materials or for weather resistance, for example, as a weather resistant coating for roofs, and the composition can have a viscosity not different from a paint, thereby allowing application, for example, by brush, roller, or spray gun, etc. The one-component translucent room temperature vulcanizable (RTV) silicone composition coating composition described herein, when applied to a substrate, can be designed to provide, for example, long-term weather resistant protection to the substrate from air and water ingress, for example, under normal conditions of movement caused by seasonal thermal expansion and / or contraction, ultraviolet light, and weather.

[0096] Working Example: All viscosity measurements were performed using a Brookfield® rotational viscometer with spindle LV-4 (designed for viscosities in the range of 1,000-2,000,000 mPa.s) or a Brookfield® rotational viscometer with spindle LV-1 (designed for viscosities in the range of 15-20,000 mPa.s) adapting the speed (shear rate) according to the polymer viscosity. Unless otherwise indicated, viscosity measurements were performed at 25° C. and a shear rate of 20 revolutions per minute.

[0097] The compositions used for the four examples and four comparative examples are shown in Tables 1a and 1b, respectively. All of the examples in Table 1a were chain extended using dimethylbis(N-ethylacetamido)silane as a chain extender, while the four comparative examples were not chain extended. The compositions used are shown below.

[0098] [Table 1]

[0099] The fumed silica used in these examples was 130 to 170 μm 2 The adhesion promoter-3 was TDK® 15AD having a BET surface area of ​​1.0 μm / g (DIN ISO 9277 DIN 66132) (supplier details) (from Wacker Chemie AG). Adhesion promoter-3 was the reaction product of aminopropyltrimethoxysilane and glycidoxypropyltrimethoxysilane.

[0100] A sealant composition made from the ingredients in Table 1a was prepared using a lab 10L Turello Mixer. Dimethylhydroxyl terminated polydimethylsiloxane was first chain extended by mixing with dimethylbis(N-ethylacetamido)silane for 10 minutes at room temperature. A plasticizer was then added to reduce the resulting viscosity of the product of the chain extension reaction. The chain extended polymer was then mixed with vinyltrimethoxysilane in the presence of an endcapping catalyst for an additional 10 minutes to produce a chain extended methoxy endcapping polymer. The other essential components of the sealant composition were added sequentially in the following order: crosslinker, tin cure catalyst, adhesion promoter, and fumed silica, and the entire mixture was mixed until thoroughly blended. The resulting mixture was then vacuum stripped for 10 minutes before the moisture scavenger was introduced.

[0101] [Table 2]

[0102] In the case of the comparative examples, whose compositions are shown in Table 1b, the same process was followed, except that the chain extension step was not carried out.

[0103] The compositions were then allowed to cure at room temperature. The tack-free time (min) was measured for each sample to determine how quickly the sample became tack-free after cure was initiated. The physical properties of the resulting elastomeric products were measured 7 days after cure was initiated at room temperature. Adhesion properties were also measured for each elastomeric product on PVC. One set of examples was measured 7 days after cure was initiated at room temperature (7d RT) and a second set of samples was tested 7 days after cure was initiated at room temperature + 1 day immersed in water (1d WI).

[0104] [Table 3]

[0105] [Table 4]

[0106] It can be seen that despite the presence of adhesion promoters in all compositions, adhesion was dramatically improved using the Examples compared to the Comparative Examples. The sealants unexpectedly exhibited better PVC adhesion than the Comparative Examples, both at room temperature and after water immersion.

[0107] Additional samples of each Example and Comparative Example were additionally tested for adhesion to a variety of other commonly used substrates.

[0108] [Table 5]

[0109] [Table 6]

[0110] [Table 7]

[0111] [Table 8]

[0112] The significantly improved adhesion to PVC (as shown in Table 2, Examples 1-4) was rather surprising since a comparable level of improved adhesion was not observed for the substrates tested as shown in Table 3. The results confirmed improved adhesion to only the PVC substrate herein.

[0113] A series of further examples and further comparative examples were prepared using the following compositions, which utilized alternative chain extenders to demonstrate that adhesion promotion is an essential factor in enhancing adhesion to PVC.

[0114] [Table 9]

[0115] [Table 10]

[0116] Formulations using methylvinylbis(N-ethylacetamido)silane as an alternative chain extender also showed good adhesion to PVC. However, Comparative Example 5 is a chain extended polymer without adhesion promoter, and has poor adhesion, as does Comparative Example 6 (also without adhesion promoter). In general, the sealants made in the examples herein showed unexpectedly better PVC adhesion than the comparative examples, both at room temperature and after water immersion. Thus, the present disclosure has provided sealants with significantly improved PVC adhesion where adhesion promoters are not sufficiently effective for robust PVC adhesion.

Claims

1. 1. A process for preparing a one-component translucent room temperature vulcanizable (RTV) silicone composition, comprising: (i) chain extending the silanol terminated polydiorganosiloxane (ai) by reacting the silanol terminated polydiorganosiloxane (ai) with a diacetamidosilane chain extender (ai) to form a chain extended silanol terminated polydiorganosiloxane intermediate (aiii); (ii) treating said chain extended silanol terminated polydiorganosiloxane intermediate (aiii) of step (i) with a compound of the structure (R) ２ -O) （４－ｂ） -Si-R １ ｂ (Wherein, b is 0, 1 or 2; R ２ is an alkyl group having 1 to 15 carbons, which may be linear or branched; R １ with one or more polyalkoxysilanes (aiv) of the formula (I) (R 2 ) selected from the group consisting of alkyl groups, which may be linear or branched having 1 to 15 carbons; cycloalkyl groups; alkenyl groups; aryl groups; aralkyl groups; aminoalkyl groups; (meth)acrylate groups; glycidyl ether groups; and groups obtained by replacing all or a portion of the hydrogens in the aforementioned organic groups with halogens) in the presence of a basic endblocking catalyst (av) to form a chain extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a); (iii) introducing a crosslinker (b), a reinforcing silica filler (c), one or more adhesion promoters (e), and one or more tin-based condensation catalysts (f) in any order to said chain-extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a) to form a mixture, said reinforcing silica filler (c) optionally being hydrophobically treated; (iv) vacuum stripping the mixture of step (iii); (v) introducing one or more moisture scavengers (d), The diacetamidosilane chain extender (aii) has the structure CH 3 -C(=O)-N(R 13 )-Si(R 14 ) 2 -N(R 13 )-C(=O)-CH 3 wherein each R 13 , which may be the same or different, is an alkyl group having 1 to 6 carbons, and each R 14 , which may also be the same or different, is an alkyl group having 1 to 6 carbons or an alkenyl group having 2 to 6 carbons.

2. 2. The process for preparing a one-component translucent room temperature vulcanizable (RTV) silicone composition according to claim 1, wherein the diacetamidosilane chain extender (aii) comprises a dialkyldiacetamidosilane selected from N,N'-(dimethylsilylene)bis[N-ethylacetamide] and / or N,N'-(dimethylsilylene)bis[N-methylacetamide], methylvinylbis(N-ethylacetamide)silane, methylvinylbis(N-methylacetamide)silane, or mixtures thereof.

3. 3. The process for preparing a one-component translucent room temperature vulcanizable (RTV) silicone composition according to claim 1 or 2, wherein the chain extended silanol terminated polydiorganosiloxane intermediate (aiii) is prepared in step (i) by mixing and reacting the silanol terminated polydiorganosiloxane (ai) with a diacetamidosilane chain extender (aii) at a temperature of 20° C. to 40° C. for 5 to 20 minutes.

4. A process for preparing a one-component translucent room temperature vulcanizable (RTV) silicone composition as described in claim 1 or 2, wherein a plasticizer is introduced to the product of step (i) containing the chain-extended silanol-terminated polydiorganosiloxane intermediate (aiii) prior to step (ii).

5. 3. The process for preparing a one-component translucent room temperature vulcanizable (RTV) silicone composition according to claim 1 or 2, wherein the reaction product of step (ii), the chain extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a), is present in the one-component translucent room temperature vulcanizable (RTV) silicone composition in an amount of 40 to 90 weight percent of the composition.

6. 3. The process for preparing a one-component translucent room temperature vulcanizable (RTV) silicone composition according to claim 1 or 2, wherein components (b), (c), (d), (e), and (f) can be introduced sequentially to the chain extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a), with mixing between each introduction.

7. 3. The process for preparing a one component translucent room temperature vulcanizable (RTV) silicone composition according to claim 1 or 2, wherein components (f), (b), and (e) are mixed together with component (a), and then component (c) is introduced and the resulting mixture is further mixed to allow chemically available residual -OH groups on the chain extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a) and / or the reinforcing silica filler (c) to condense with the crosslinker (b) and / or the adhesion promoter (e) to produce alcohol by-products which are then removed by vacuum stripping at a predetermined controlled temperature of 50°C to 100°C, followed by adding component (d).

8. 3. The process for preparing a one-component translucent room temperature vulcanizable (RTV) silicone composition according to claim 1 or 2, wherein the first component added to the chain extended alkoxy endblocked polydiorganosiloxane polymer reaction product (a) is the reinforcing silica filler (c), followed by the addition of other components in any order of addition.

9. 10. A one-component translucent room temperature vulcanizable (RTV) silicone composition obtained or obtainable by the process of claim 1.

10. 1. A one-component translucent room temperature vulcanizable (RTV) silicone composition comprising: (a) subjecting a chain extended, alkoxy endblocked polydiorganosiloxane polymer reaction product (a) of the process of steps (i) and (ii) below to: step (i) chain extending the silanol terminated polydiorganosiloxane (ai) by reacting the silanol terminated polydiorganosiloxane (ai) with a diacetamidosilane chain extender (ai) to form a chain extended silanol terminated polydiorganosiloxane intermediate (aiii); Step (ii) reacting the chain extended silanol terminated polydiorganosiloxane intermediate (aiii) of step (i) with a compound having the structure (R) ２ -O) （４－ｂ） -Si-R １ ｂ (Wherein, b is 0, 1 or 2; R ２ is an alkyl group having 1 to 15 carbons, which may be linear or branched; R １ But, R ２ a cycloalkyl group; an alkenyl group; an aryl group; an aralkyl group; an aminoalkyl group; a (meth)acrylate group; a glycidyl ether group; and groups obtained by replacing all or a part of the hydrogens in the aforementioned organic groups with halogens) in the presence of a basic end-capping catalyst (av), (b) a crosslinking agent; and (c) a reinforcing silica filler, which may optionally be hydrophobically treated; and (d) one or more moisture scavengers; and (e) one or more adhesion promoters; (f) together with a tin-based catalyst, The diacetamidosilane chain extender (aii) has the structure CH 3 -C(=O)-N(R 13 )-Si(R 14 ) 2 -N(R 13 )-C(=O)-CH 3 wherein each R 13 , which may be the same or different, is an alkyl group having 1 to 6 carbons, and each R 14 , which may also be the same or different, is an alkyl group having 1 to 6 carbons or an alkenyl group having 2 to 6 carbons.

11. A translucent cured sealant which is the cured product of the composition of claim 9 or 10.

12. 3. Use of a one-component translucent room temperature vulcanizable (RTV) silicone composition prepared by the process of claim 1 or 2 for improving adhesion to polyvinyl chloride substrates.

13. 11. Use of the one-component translucent room temperature vulcanizable (RTV) silicone composition according to claim 9 or 10 as a low modulus silicone sealant composition for sealing glazing units for buildings, as an elastomeric coating composition for weather resistance, in the manufacture of PVC window and door frames.

14. 1. A method for filling a space between two substrates, one or both of which are PVC substrates, thereby creating a seal therebetween, comprising: a) providing a one-component translucent room temperature vulcanizable (RTV) silicone composition according to claim 9 or 10; b) applying the one-component translucent room temperature vulcanizable (RTV) silicone composition to a first substrate and contacting a second substrate with the silicone composition applied to the first substrate; or and c) filling a space formed by the arrangement of a first substrate and a second substrate with the one-component translucent room temperature vulcanizable (RTV) silicone composition and curing the composition, wherein the first substrate, the second substrate, or the first and second substrates are made from polyvinyl chloride (PVC).

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