WO2023230756A1

WO2023230756A1 - Sealant composition

Info

Publication number: WO2023230756A1
Application number: PCT/CN2022/095929
Authority: WO
Inventors: Xiuyan WANG; Yi Guo; Qiang Hu; Jiang PENG; Zhiping ZENG
Original assignee: Dow Silicones Corp
Current assignee: Dow Silicones Corp
Priority date: 2022-05-30
Filing date: 2022-05-30
Publication date: 2023-12-07
Anticipated expiration: 2024-11-30
Also published as: CN119213059B; CN119213059A

Abstract

A one-part hot porous surface condensation curable silicone composition comprising organopolysiloxane polymers having at least two alkoxy groups per molecule and titanate-based or zirconate-based catalysts wherein the hot porous substrate is at a temperature of at least 40℃. The porous substrates may for example be construction materials including stone, marble, brick, concrete, cement and other cementitious substrates. It also relates to a method for applying a one-part hot porous surface condensation curable silicone composition on to a hot porous substrate at a temperature of at least 40℃ and the use of said one-part hot porous surface condensation curable silicone composition to treat porous substrates at a temperature of at least 40℃.

Description

SEALANT COMPOSITION

This relates to a one-part hot porous surface condensation curable silicone composition comprising organopolysiloxane polymers having at least two alkoxy groups per molecule and titanate-based or zirconate-based catalysts wherein the hot porous substrate is at a temperature of at least 40℃. The porous substrates may for example be construction materials including stone, marble, brick, concrete, cement and other cementitious substrates. It also relates to a method for applying a one-part hot porous surface condensation curable silicone composition on to a hot porous substrate at a temperature of at least 40℃ and the use of said one-part hot porous surface condensation curable silicone composition to treat porous substrates at a temperature of at least 40℃.

Condensation curable silicone compositions are well known. Generally, most of such compositions are designed to be room temperature vulcanizable (RTV) , where room temperature is from about 20℃ to 25℃. They usually comprise an -OH end-blocked diorganopolysiloxane polymer or an alkoxy end-blocked polydiorganosiloxane which may have an alkylene link between the terminal and penultimate silicon atoms as well as one or more suitable cross-linking agents designed to react with the –OH and/or alkoxy groups and thereby cross-link the composition to form an e.g., elastomeric sealant product and one or more condensation cure catalysts. Additional ingredients such as reinforcing fillers, non-reinforcing fillers, adhesion promotors, diluents (e.g., plasticisers and/or extenders) , chain extenders, flame retardants, solvent resistant additives, biocides and the like are often also incorporated into these compositions as and when required.

They may be one-part compositions or multiple-part, e.g., two-part compositions. One-part condensation curing (RTV) silicone compositions are generally utilised to generate skin or diffusion cured silicone elastomers. It is well known to people skilled in the art that alkoxy titanium compounds and /or alkoxy zirconium compounds i.e., alkyl titanates-are suitable catalysts for curing such one component moisture curable silicones. One-part condensation curing silicone compositions are generally designed not to contain any water/moisture in the composition so far as possible, i.e., they are generally stored in a substantially anhydrous form to prevent premature cure during storage before use. Skin or diffusion cure (e.g., moisture/condensation) takes place by the formation of a cured skin at the composition/air interface subsequent to the sealant/encapsulant being applied on to a substrate surface. Subsequent to the generation of the surface skin the cure speed is dependent on the speed of diffusion of moisture from the sealant/encapsulant interface with air to the inside (or core) of the layer of silicone composition applied, and the diffusion of condensation reaction by-product/effluent from the inside (or core) to the outside (or surface) of the material and the gradual thickening of the cured skin over time from the outside/surface to the inside/core. Such one-part condensation curing silicone compositions are applied in a layer that is thinner than typically 15 mm. Such compositions applied in layers thicker than 15 mm are known to lead to uncured material in the depth of the material, because moisture is very slow to diffuse into very deep sections. The main, if not sole source, of moisture in these compositions are inorganic fillers, e.g., silica or calcium carbonate when present. Said fillers may be rendered anhydrous before inter-mixing with other ingredients or water/moisture may be extracted from the mixture during the mixing process to ensure that the resulting sealant composition is substantially anhydrous.

Silicone sealant compositions having at least one Si-alkoxy bond, e.g., Si-methoxy bond in the terminal reactive silyl group and having a polydiorganosiloxane polymeric backbone are widely used for sealants in the construction industry because they have good adhesion, and weather resistance, and the like. The construction industry also prefers one-component compositions to negate the need for mixing ingredients before application and compositions with excellent workability.

However, the application of one-part condensation curable silicone compositions to substrates such as stone, marble, brick, concrete, cement and other cementitious substrates is a problem for the construction industry when the substrate surface is at elevated temperatures of e.g., at least 40℃. This is because whilst one-part condensation curable silicone compositions are highly desirable for such purposes, given they have little or no deleterious effects on the porous substrates against which they are applied and subsequently cured, such compositions, especially those comprising organopolysiloxane polymers having at least two alkoxy groups per molecule and titanate-based or zirconate-based catalysts, generate bubbles in the composition during the curing process when the substrate is hot. This can occur regularly in sunny weather and hot climates when the sun heats the substrate or associated building materials to temperatures which often exceed 40℃, especially when the sealant used has been stored for several months before use. These bubbles are unacceptable and increase the volume of the cured product by as much as two or three times compared to room temperature cured materials, not cured on a hot porous substrate. Additionally, the bubbles cause blistering and have a significantly negative affect on adhesion between the cured silicone product (e.g., sealant) and the substrate.

Without being bound to current theories it is believed that when alkoxy silicone compositions (often used as sealants) are applied onto hot porous substrates at temperatures of at least 40℃, especially hydrophilic hot porous substrates, more and more moisture/water vapor condenses at the interface of the sealant and porous substrates, driven by capillary action and reactivity of moisture with the composition. This results in more and more hydrolyzation of alkoxy silyl groups at the interface between a hot porous substrate at least 40℃ and consequently much increased alcohol, typically methanol, generation given the elevated temperature of the substrate. It is believed the bubbling is an issue because the alcohol (methanol) generation speed at the interface is higher than its permeation speed through the bulk curing composition, e.g., sealant composition at the elevated temperature of the substrate. The bubbles are consequently trapped during cure in these conditions not least because of the process by which such compositions cure, i.e., with the initial formation of a skin preventing the escape of the bubbles especially as at elevated temperatures will cause the skin to form quicker than when the sealant cures at room temperature or thereabouts. This is a particular problem when using such compositions as e.g., sealants in countries with hot climates. There is provided herein a one-part hot porous surface condensation curable silicone composition comprising organopolysiloxane polymers having at least two alkoxy groups per molecule and titanate-based or zirconate-based catalysts, wherein the hot porous substrates are at a temperature of at least 40℃one-part hot porous surface condensation curable silicone composition comprising the following components:

(a) an organopolysiloxane polymer having at least two hydroxyl or hydrolysable groups per

molecule of the formula

X _3-nR _nSi-Z- (R ¹ _ySiO _(4-y) /2) _z –SiR ¹ ₂ -Z-Si-R _nX _3-n (1)

in which each X is independently a hydroxyl group or an alkoxy group, each R is an alkyl, alkenyl or aryl group, each R ¹ is an X group, alkyl group, alkenyl group or aryl group and Z is a divalent organic group;

n is 0 or 1, y is 0, 1 or 2, and preferentially 2 and z is an integer such that said organopolysiloxane polymer has a viscosity of from 10,000 to 150,000 mPa. s at 25℃, in an amount of from 30 to 90 weight % (wt. %) of the composition;

(b) one or more reinforcing fillers selected from precipitated silica, fumed silica or precipitated calcium carbonate;

(c) a silane compound having two hydrolysable groups per molecule of the formula

R ³ ₂ –Si –R ⁴ ₂

Wherein each group R ³ may be the same or different and is a hydrolysable group selected from alkoxy or acetoxy groups and each R ⁴ group is the same or different and independently represents an alkyl group having from 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aryl group or a fluorinated alkyl group, which silane compound (c) is present in the composition in an amount of from 1 to 10 wt. %of the composition;

(d) Tetra-n-propoxysilane present in an amount of from 0.40 to 3.5 wt. %of the composition;

(e) a silicon containing compound having three or more hydrolysable groups per molecule, selected from

(e) (a’) , a 1, 3, 5-tris (trialkoxysilylalkyl) isocyanurate

(e) (b’) a siloxane oligomer of the structure

Si- ( (O-Si (CH ₃) ₂) _n’- (R ⁷ –Si (CH ₃) ₂ –O-Si (CH ₃) ₂) _z’–R ⁷ –Si (OR ⁸) ₃) ₄;

where each R ⁷ may be the same or different and may be the same as R ⁵ and each R ⁸ may be the same or different and may be the same as R ⁶, n’ is an integer and z’ is zero or 1; or

(e) (c’) a siloxane oligomer of the structure

R ⁹-Si- ( (O-Si (CH ₃) ₂) _n’- (R ⁷ –Si (CH ₃) ₂ –O-Si (CH ₃) ₂) _z’–R ⁷ –Si (OR ⁸) ₃) ₃

where again R ⁷, R ⁸ n’ and z’ are as defined above and R ⁹ may be the same as R ⁸ which silicon containing compound (e) is present in the composition in an amount of from 0.1 to 5 wt. %of the composition; and

(f) a catalyst comprising a titanate-based compound, a zirconate-based compound or a mixture thereof.

The total wt. %of the composition is 100 wt. %. The one-part hot porous surface condensation curable silicone composition herein is a one-part condensation curable silicone composition designed to be curable on substrates which are at temperatures of at least 40℃. Such one-part condensation curable silicone composition when cured contain no or minimal visible bubbles.

The one-part hot porous surface condensation curable silicone composition comprising organopolysiloxane polymers having at least two alkoxy groups per molecule and titanate-based or zirconate-based catalysts one-part hot porous surface condensation curable silicone composition is curable on a hot porous surface (at least 40℃) with no or minimal bubble generation.

There is also provided herein an elastomeric sealant material adhered to a hot porous substrate at a temperature of at least 40℃ which elastomeric sealant material is the cured product of the composition as herein described. The elastomeric sealant material contains no or substantially no trapped bubbles.

There is also provided a method of applying a one-part hot porous surface condensation curable silicone composition to a hot porous substrate at a temperature of at least 40℃ comprising the steps of

(i) applying a one-part hot porous surface condensation curable silicone composition on to the hot porous substrate having a temperature of at least 40℃, wherein the a one-part hot porous surface condensation curable silicone composition comprises the following components: -

(a) an organopolysiloxane polymer having at least two hydroxyl or hydrolysable groups per molecule of the formula

X _3-nR _nSi-Z- (R ¹ _ySiO _(4-y) /2) _z –SiR ¹ ₂ -Z-Si-R _nX _3-n (1)

R ³ ₂ –Si –R ⁴ ₂

(e) (a’) , a 1, 3, 5-tris (trialkoxysilylalkyl) isocyanurate

(e) (b’) a siloxane oligomer of the structure

(e) (c’) a siloxane oligomer of the structure

(f) a catalyst comprising a titanate-based compound, a zirconate-based compound or a mixture thereof; and

(ii) curing the said composition.

A method of bonding silicone sealant to a hot porous substrate at a temperature of at least 40℃., comprising the steps of preparing a one-part hot porous surface condensation curable silicone composition as hereinbefore described, contacting a surface of a hot porous substrate at a temperature of at least 40℃. with the one-part hot porous surface condensation curable silicone composition and curing said a one-part hot porous surface condensation curable silicone composition thereby obtaining a silicone sealant bonded to a surface of the hot porous substrate. A sealant bonded to a hot porous substrate at a temperature of at least 40℃ obtained or obtainable preparing a one-part hot porous surface condensation curable silicone composition as hereinbefore described, contacting a surface of a hot porous substrate at a temperature of at least 40℃ with the one-part hot porous surface condensation curable silicone composition and curing said a one-part hot porous surface condensation curable silicone composition.

Use of a one-part hot porous surface condensation curable silicone composition comprising the following components:

molecule of the formula

X _3-nR _nSi-Z- (R ¹ _ySiO _(4-y) /2) _z –SiR ¹ ₂ -Z-Si-R _nX _3-n (1)

R ³ ₂ –Si –R ⁴ ₂

(e) (a’) , a 1, 3, 5-tris (trialkoxysilylalkyl) isocyanurate

(e) (b’) a siloxane oligomer of the structure

(e) (c’) a siloxane oligomer of the structure

(f) a catalyst comprising a titanate-based compound, a zirconate-based compound or a mixture thereof;

as a means of applying a sealant on to the hot porous substrate having a temperature of at least 40℃, whilst minimising the entrapment of bubbles in the resulting cured sealant on the surface of said hot porous substrate after the composition has cured.

There is also provided a use of the aforementioned composition as a sealant in the facade, insulated glass, window construction, automotive, solar and construction fields.

There is also provided a method for filling a space between two substrates so as to create a seal therebetween, comprising:

a” ) providing a silicone composition as hereinbefore described, and either

b” ) applying a one-part hot porous surface condensation curable silicone composition to a first substrate, and bringing a second substrate in contact with the silicone composition that has been applied to the first substrate wherein either or both of said substrates are porous substrates at a temperature of at least 40℃, or

c” ) filling a space formed by the arrangement of a first substrate and a second substrate wherein either or both of said substrates are porous substrates at a temperature of at least 40℃, with the one-part hot porous surface condensation curable silicone composition and

d” ) curing same.

Preferably the first substrate and/or second substrate is/are stone, marble, brick, concrete, cement and other cementitious substrates, combinations thereof, or combinations with other non-porous building materials.

The concept of “comprising” where used herein is used in its widest sense to mean and to encompass the notions of “include” and “consist of” .

For the purpose of this application “substituted” means one or more hydrogen atoms in a hydrocarbon group has been replaced with another substituent. Examples of such substituents include, but are not limited to, halogen atoms such as chlorine, fluorine, bromine, and iodine; halogen atom containing groups such as chloromethyl, perfluorobutyl, trifluoroethyl, and nonafluorohexyl; oxygen atoms; oxygen atom containing groups such as (meth) acrylic and carboxyl; nitrogen atoms; nitrogen atom containing groups such as amino-functional groups, amido-functional groups, and cyano-functional groups; sulphur atoms; and sulphur atom containing groups such as mercapto groups.

The one-part hot porous surface condensation curable silicone composition which is suitable for application on porous substrates at temperatures of at least 40℃ is designed for the purpose of bonding it to the surfaces of hot porous substrates, such as stone, marble, brick, concrete, cement and other cementitious substrates combinations thereof, and combinations with other non-porous building materials. The said one-part hot porous surface condensation curable silicone composition may also be used to bond combinations of the hot porous surfaces together, as well as with other conventional building materials, such as glass and aluminum. The said one-part hot porous surface condensation curable silicone composition is brought into contact with the hot porous surface by conventional means such as by extrusion, coating, injection, knifing and rolling. The one-part hot porous surface condensation curable silicone composition is particularly intended to be used when the surface of the porous substrate onto which it is to be applied is at a temperature of at least 40℃. Porous surfaces which are at a temperature lower than 40℃. may form some bubbles, but the reduction of bubbles is significant at temperatures of 40℃ or above, when the method described herein is used. After said one-part hot porous surface condensation curable silicone composition is applied to the hot porous substrate, it is exposed to atmospheric moisture causing it to cure to a silicone sealant bonded to the hot porous substrate surface wherein there is a reduction in the number and size of bubbles in the cured silicone sealant compared to if a standard RTV silicone sealant were applied onto a hot porous substrate at 40℃ or more. Hence, it can be said that the one-part hot porous surface condensation curable silicone composition as herein described is curable on a hot porous surface (at least 40℃) with a reduction in bubble generation. The undesirable bubbles form primarily at the interface between the hot porous substrate and the cured silicone surface. The temperature of the environment in which this sealant composition is designed cure are significantly higher e.g., >10℃ higher than typically designed and as such the cure time and working time for most standard sealant formulations will be shorter than usual. The said one-part hot porous surface condensation curable silicone compositions herein however have increased working time compared to standard sealant compositions at temperatures of 40℃ or more. The components of the composition will now be described in more detail.

Organopolysiloxane polymer having at least two hydroxyl or hydrolysable groups per molecule (a)

The organopolysiloxane polymer having at least two hydroxyl or hydrolysable groups per molecule

(a) has the following formula

X _3-nR _nSi-Z- (R ¹ _ySiO _(4-y) _/2) _z –SiR ¹ ₂ -Z-Si-R _nX _3-n (1)

In the above formula each X is independently a hydroxyl group or an alkoxy group, alternatively an alkoxy group. Preferably said alkoxy group has between 1 and 10 carbons, Illustrative alkoxy groups are methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, t-butoxy, isobutoxy, pentoxy, hexoxy and 2-ethylhexoxy; dialkoxy groups, such as methoxymethoxy or ethoxymethoxy and alkoxyaryloxy, such as ethoxyphenoxy groups; alternatively, each X is an alkoxy group having from one and six carbons, alternatively having from one and four carbons or alternatively is a methoxy or ethoxy group.

Each R group is an alkyl, alkenyl or aryl group, alternatively each R is an alkyl group having from 1 to 6 carbons, an alkenyl group having from 2 to 6 carbons such as vinyl, allyl and hexenyl groups or an aryl group having from 6 to 12 carbons; alternatively each R is an alkyl group having from 1 to 6 carbons, or an aryl group having from 6 to 12 carbons; alternatively each R is an alkyl group having from 1 to 6 carbons, alternatively each R is an ethyl group or a methyl group. In one embodiment R may include substituted aliphatic organic groups such as 3, 3, 3-trifluoropropyl groups aminoalkyl groups, polyaminoalkyl groups, and/or epoxyalkyl groups.

Each R ¹ is an X group, or and R group, with the proviso that cumulatively at least two X groups and/or R ¹ groups per molecule are hydroxyl or hydrolysable groups. alternatively each R ¹ is an R group. It is possible that some R ¹ groups may be siloxane branches off the polymer backbone which branches may have terminal groups as hereinbefore described.

Each Z is a divalent organic group, typically an alkylene having from 2 to 10 carbons, such as for example, an ethylene, propylene, butylene, pentylene and/or hexylene group; alternatively, an alkylene group having 2 to 6 carbons, alternatively an alkylene group having from 2 to 5 carbons. Subscript n is zero or 1, alternatively is zero; each subscript y is 0, 1 or 2, and preferably 2. Whilst y is 0, 1 or 2, substantially y= 2, e.g., at least 90%, alternatively 95%of R ¹ _ySiO _(4-y) /2 groups are characterized with y = 2. Subscript z is an integer such that said organopolysiloxane polymer has a viscosity of from 10,000 to 150,000 mPa. s, alternatively from 30,000 to 140,000mPa. s at 25℃, therefore z is an integer of from approximately 300 to 2000. The viscosity of component (a) may be measured by any suitable method such as in accordance with corporate test method CTM 0050, which is publicly available, and which is based on ASTM D 1084-16 method B, using a Brookfield HBDV-III Ultra Rheometer equipped with a cone-and-plate geometry using spindle 52. All viscosity measurements herein are taken at 25℃ unless otherwise indicated. Alternatively, the viscosity may be measured using a Modular Compact Rheometer (MCR) 302 rheometer from Anton Paar GmbH of Graz, Austria with the most suitable settings and plates for the viscosity concerned. For example, viscosities in the range of 30,000-160,000 mPa. s may be measured using the MCR 302 rheometer with a 40 mm diameter cone-plate and a shear rate of 1s ^-1; viscosities in the range 2000-30,000 mPa. s may be measured using the MCR 302 rheometer with a 50 mm diameter cone-plate and a shear rate of 1s ^-1; and viscosities in the range 10-2000 mPa. s may be measured using the MCR 302 rheometer with a 75 mm diameter cone-plate and a shear rate of 1s ^-1.

,Component (a) is present in the one-part hot porous surface condensation curable silicone composition in an amount of from 30 to 90 wt. %of the composition, alternatively 35 to 75%, alternatively 35 to 60 wt. %of the composition.

Organopolysiloxane polymer (a) can be a single siloxane represented by Formula (1) or it can be mixtures of organopolysiloxane polymers represented by the aforesaid formula. Hence, it may be a "siloxane polymer mixture" so organopolysiloxane polymer (a) is meant to include any individual organopolysiloxane polymer (a) or mixtures of organopolysiloxane polymer (a) .

The Degree of Polymerization (DP) , (i.e., in the above formula substantially z) , is usually defined as the number of monomeric units in a macromolecule or polymer or oligomer molecule of silicone. Synthetic polymers invariably consist of a mixture of macromolecular species with different degrees of polymerization and therefore of different molecular weights. There are different types of average polymer molecular weight, 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 determined by gel permeation chromatography (GPC) with precision of about 10-15%using polystyrene standards.

This technique is standard and yields Mw, Mn and polydispersity index (PI) . The degree of polymerisation (DP) =Mn/Mu where Mn is the number-average molecular weight coming from the GPC measurement and Mu is the molecular weight of a monomer unit. PI=Mw/Mn. The DP is linked to the viscosity of the polymer via Mw, the higher the DP, the higher the viscosity. In the present disclosure the number average molecular weight and weight average molecular weight values of component (a) herein may, for example, be determined using a Waters 2695 Separations Module equipped with a vacuum degasser, and a Waters 2414 refractive index detector (Waters Corporation of MA, USA) . The analyses may then be performed using certified grade toluene flowing at 1.0 mL/min as the eluent. Data collection and analyses may be performed using Waters Empower GPC software.

One or more reinforcing fillers (b)

The one or more reinforcing fillers identified as component (b) herein are selected from precipitated silica, fumed silica, precipitated calcium carbonate, or a mixture of two or more thereof.

Typically, the surface area of the reinforcing filler (b) is at least 15 m ²/g in the case of precipitated calcium carbonate measured in accordance with the BET method (ISO 9277: 2010) , alternatively 15 to 50 m ²/g, alternatively 15 to 25 m ²/g.

Silica reinforcing fillers have a typical surface area of at least 50 m ²/g in accordance with the BET method (ISO 9277: 2010) . In the case of high surface area fumed silica and/or high surface area precipitated silica, these may have surface areas of from 75 to 400 m ²/g measured in accordance with the BET method (ISO 9277: 2010) , alternatively of from 100 to 300 m ²/g in accordance with the BET method (ISO 9277: 2010) .

The reinforcing fillers (b) may be hydrophobically treated for example with one or more aliphatic acids, e.g., a fatty acid such as stearic acid or a fatty acid ester such as a stearate, or with organosilanes, organosiloxanes, or organosilazanes hexaalkyl disilazane or short chain siloxane diols to render the filler (s) hydrophobic and therefore easier to handle and obtain a homogeneous mixture with the other adhesive components. Specific examples organosilanes, organosiloxanes, or organosilazanes may include, but are not restricted to, silanol terminated trifluoropropylmethylsiloxane, silanol terminated vinyl methyl (ViMe) siloxane, silanol terminated methyl phenyl (MePh) siloxane, liquid hydroxyldimethyl-terminated polydiorganosiloxane containing an average from 2 to 20 repeating units of diorganosiloxane in each molecule, hydroxyldimethyl terminated phenylmethyl Siloxane, hexaorganodisiloxanes, such as hexamethyldisiloxane, divinyltetramethyldisiloxane; hexaorganodisilazanes, such as hexamethyldisilazane (HMDZ) , divinyltetramethyldisilazane and tetramethyldi (trifluoropropyl) disilazane; hydroxyldimethyl terminated polydimethylmethylvinyl siloxane, octamethyl cyclotetrasiloxane, and silanes including but not limited to methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, chlorotrimethyl silane, dichlorodimethyl silane, trichloromethyl silane. The surface treatment of the fillers makes them easily wetted by component (a) . These surface modified fillers are preferably in a finely divided form and do not clump and can be homogeneously incorporated into the silicone polymer (a) This results in improved room temperature mechanical properties of the uncured compositions. The fillers may be pre-treated or may be treated in situ when being mixed with component (a) . Asmall amount of water can be added together with the silica treating agent (s) as processing aid.

Depending on the filler (s) chosen the reinforcing fillers (b) may be present in an amount of from 2.5 to 60 %by weight (wt. %) of the one-part hot porous surface condensation curable silicone composition. In the case when the selected fillers are precipitated silica and/or fumed silica or a combination thereof the inorganic fillers (b) are present in a range of from about 5.0 to 35 wt. %of the composition, alternatively of from 5 to 30 wt. %of the composition, alternatively of from 5 to 25 wt.%of the composition. However, when reinforcing filler (b) is precipitated calcium carbonate, the composition will tend to include a larger wt. %of the composition, e.g., from 25 to 60 wt. %of the composition, alternatively of from 30 to 60 wt. %of the composition, alternatively of from 35 to 55 wt. %of the composition. When component (b) is a mixture of silica and precipitated calcium carbonate the wt. %will typically somewhere therebetween.

Silane compound having two hydrolysable groups per molecule (c)

Component (c) is a silane having two hydrolysable groups per molecule of the formula

R ³ ₂ –Si –R ⁴ ₂

Each group R ³ may be the same or different and is a hydroxyl or hydrolysable group. Examples of preferred R ³ groups may be selected from the group of alkoxy or acetoxy groups. Most preferably the reactable groups are alkoxy groups having from 1 and 10 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, and t-butoxy groups. Each R ⁴ group is the same or different and independently represents an alkyl group having from 1 to 10 carbon atoms, an alkenyl group, such as vinyl, propenyl and hexenyl groups. an alkynyl group an aryl group such as phenyl, or a fluorinated alkyl group. Specific examples of suitable silanes for component (c) include: -alkenyl alkyl dialkoxysilanes such as vinyl methyl dimethoxysilane, vinyl ethyldimethoxysilane, vinyl methyldiethoxysilane and vinylethyldiethoxysilane; dialkyl dialkoxysilanes such as dimethyl dimethoxysilane, diethyldimethoxysilane, dimethyldiethoxysilane and diethyldiethoxysilane; dialkenyl dialkoxysilanes such as divinyl dimethoxysilane, divinyl dimethoxysilane, divinyl diethoxysilane and divinyldiethoxysilane; phenyl alkyl dialkoxysilanes such as phenyl methyl dimethoxysilane, phenyl ethyldimethoxysilane, phenyl methyldiethoxysilane and phenyl ethyldiethoxysilane; alkenyl phenyl dialkoxysilanes such as vinyl phenyl dimethoxysilane, vinyl phenyl dimethoxysilane, vinyl phenyl diethoxysilane and vinyl phenyl diethoxysilane.

Component (c) may alternatively diacetoxysilane equivalents to the above or dihydroxy equivalents to the above di 3, 3, 3-trifluoropropyldimethoxysilane. Component (c) may alternatively be a mixture of two or more of the above.

Component (c) is present in a range of from 1 to 10 wt. %of the one-part hot porous surface condensation curable silicone composition, alternatively from 1.25 to 7.5 weight %of the composition, alternatively from 1.5 to 4.0 weight %of the composition.

Tetra-n-propoxysilane (d)

Component (d) is Tetra-n-propoxysilane (TPOS) which has the following structure

Si- (O -CH ₂CH ₂CH ₃) ₄

It was surprisingly found that the addition of tetra-n-propoxysilane, component (d) into one-part room temperature vulcanisable (RTV) silicone compositions appeared to solve the long-term industry problem caused by bubbling when such sealant compositions are applied onto substrates such as stone, marble, brick, concrete, cement and other cementitious substrates at temperatures of at least 40℃ in countries with high temperature climates (>40℃) . The introduction of tetra-n-propoxysilane, component (d) dramatically and unexpectedly reduced the number and size of bubbles produced in such situations. It was found that component (d) needed to be present in an amount of from 0.40 to 3.5 wt. %of the one-part hot porous surface condensation curable silicone composition, alternatively 0.40 to 3.0 wt. %of the composition, alternatively 0.40 to 2.5 wt. %of the composition, alternatively 0.40 to 2.5 wt. %of the composition, alternatively 0.50 to 2.0 wt. %of the composition.

Component (e)

Component (e) of the one-part hot porous surface condensation curable silicone composition is a silicon containing compound selected from: -

(e) (a’) a 1, 3, 5-tris (trialkoxysilylalkyl) isocyanurate for example a 1, 3, 5-tris (trialkoxysilylalkyl) isocyanurate having the following structure : -

Wherein each R ⁵ may be the same or different and is a divalent alkylene group having from 2 to 10 carbons, alternatively from 2 to 6 carbons, alternatively from 2 to 5 carbons and each R ⁶ is the same or different and is an alkyl group having from 1 to 10 carbons alternatively from 1 to 6 carbons, alternatively from 1 to 4 carbons, alternatively a methyl group or an ethyl group.

Generally, (e) (a’) , the 1, 3, 5-tris (trialkoxysilylalkyl) isocyanurate may be prepared by the reaction of a chloro-alkyl tri-alkoxy silane with an alkali metal cyanate in a polar non-protic solvent. For example, a preferred 1, 3, 5-tris (trialkoxysilylalkyl) isocyanurate (e) (a’) is prepared by the reaction of chloro-propyl tri-methoxy silane with potassium cyanate in a suitable solvent such as dimethylformamide (DMF) . This results in an isocyanurate being produced where each R ⁵ is a propylene group and each R ⁶ is a methyl group, namely tris- (trimethoxysilylpropyl) isocyanurate as depicted below.

Alternatively, the silicon containing compound may be (e) (b’) and/or (e) (c’) , wherein (e) (b’) is a siloxane oligomer of the structure

(e) (c’) a siloxane oligomer of the structure

R ⁹-Si- ( (O-Si (CH ₃) ₂) _n’- (R ⁷ –Si (CH ₃) ₂ –O-Si (CH ₃) ₂) _z’–R ⁷ –Si (OR ⁸) ₃) ₃ where again R ⁷, R ⁸ n’ and z’ are as defined above and R ⁹ may be the same as R ⁸ or may be an aryl group or a fluorinated alkyl group.

In one embodiment in (e) (b’) or (e) (c’) , each R ⁷ may be the same or different and may be a divalent alkylene having from 2 to 5 carbons, each R ⁸ may be the same or different and comprises from 1 and 5 carbons, alternatively each R ⁷ is the same and may be the same or different and may be a divalent alkylene having from 2 to 5 carbons, each R ⁸ may be the same or different and comprises from 1 and 5 carbons, alternatively each R ⁷ is the same and contains two or three carbons 2 or 3, alternatively 2 carbons, each R ⁸ is the same and has from 1 to 3 carbons, alternatively is methyl or ethyl, alternatively is methyl and z’ is 1. Subscript n’ is an integer, alternatively each n’ is an integer of from 1 and 1000, alternatively of from 2 to 750. In the case of (e) (c’) R ⁹ is preferably R ⁸ or R ⁸ or may be an aryl group or a fluorinated alkyl group.

Component (e) is being utilised as a cross-linker and given their structures they are designed to provide cured sealants having both high elasticity and low modulus.

It will be appreciated that each of (e) (a’) (e) (b’) or (e) (c’) , have three or more trialkoxy silyl terminal groups per molecule.

The silicon containing compounds (e) is present in an amount of from 0.1 to 5 wt. %of the one-part hot porous surface condensation curable silicone composition, alternatively present in an amount of from 0.1 to 4 wt. %of the composition, alternatively in an amount of from 0.1 to 2.5 wt. %of the composition, alternatively in an amount of from 0.1 to 1.5 wt. %of the composition, alternatively in an amount of from 0.1 to 1.0 wt. %of the composition.

A catalyst comprising a titanate-based compound, a zirconate-based compound or a mixture thereof (f)

Component (f) comprises a condensation catalyst (iv) which increases the speed at which the composition cures. Titanate-based and/or zirconate-based catalysts may comprise a compound according to the general formula Ti [OR ²²] ₄ or Zr [OR ²²] ₄ where each R ²² may be the same or different and represents a monovalent, primary, secondary or tertiary aliphatic hydrocarbon group which may be linear or branched containing from 1 to 10 carbon atoms. Optionally the titanate may contain partially unsaturated groups. However, preferred examples of R ²² include but are not restricted to methyl, ethyl, propyl, isopropyl, butyl, tertiary butyl and a branched secondary alkyl group such as 2, 4-dimethyl-3-pentyl. In one embodiment each R ²² is the same, and R ²² is an isopropyl, branched secondary alkyl group or a tertiary alkyl group, in particular, tertiary butyl. Suitable examples include for the sake of example, tetra n-butyl titanate, tetra t-butyl titanate, tetra t-butoxy titanate, tetraisopropoxy titanate and zirconate equivalents.

Alternatively, the titanate may be chelated. The chelation may be with any suitable chelating agent such as an alkyl acetylacetonate such as methyl or ethyl acetylacetonate. Alternatively, the titanate may be monoalkoxy titanates bearing three chelating agents such as for example 2-propanolato, tris isooctadecanoato titanate and diisopropoxydiethylacetoacetate titanate or titanium ethyl acetoacetate complexes mixed with a methyl-trimethoxy silane. Component (f) may be present in any suitable amount, such as from 0.05 wt. %to 1.5 wt. %of the one-part hot porous surface condensation curable silicone composition, alternatively in an amount of from 0.05 wt. %to 1.25 wt. %of the composition, alternatively in an amount of from 0.1 wt. %to 1.0 wt. %of the composition, alternatively in an amount of from 0.1 wt. %to 0.75 wt. %of the composition.

Components (c) + (d) + (e) are present cumulatively in the one-part hot porous surface condensation curable silicone composition in a range of from 1.5 to 18.5 wt. %of the composition.

Alternatively, components (c) + (d) + (e) may be present cumulatively in a range of from 1.5 to 10 wt. %of the composition; alternatively, components (c) + (d) + (e) may be present cumulatively in a range of from 2.0 to 7.5 wt. %of the composition; alternatively, components (c) + (d) + (e) may be present cumulatively in a range of from 2.5 to 7.5 wt. %of the composition.

Optional Additives

Optional additives may be used if required necessary. These may include non-reinforcing fillers, pigments, rheology modifiers, cure modifiers, adhesion promoters, tin (iv) condensation catalysts, and fungicides and/or biocides and the like; It will be appreciated that some of the additives may be included in more than one list of additives. Such additives would then have the ability to function in all the different ways referred to.

Non-reinforcing fillers

Non-reinforcing fillers, which might be used in addition to component (b) herein include aluminite, calcium sulphate (anhydrite) , gypsum, nepheline, svenite, quartz, calcium sulphate, magnesium carbonate, ground calcium carbonate, clays such as kaolin, aluminium trihydroxide, magnesium hydroxide (brucite) , graphite, copper carbonate, e.g., malachite, nickel carbonate, e.g., zarachite, barium carbonate, e.g., witherite and/or strontium carbonate e.g., strontianite.

Aluminium oxide, silicates from the group consisting of olivine group; garnet group; aluminosilicates; ring silicates; chain silicates; and sheet silicates. The olivine group comprises silicate minerals, such as but not limited to, forsterite and Mg ₂SiO ₄. The garnet group comprises ground silicate minerals, such as but not limited to, pyrope; Mg ₃Al ₂Si ₃O ₁₂; grossular; and Ca ₂Al ₂Si ₃O ₁₂. Aluminosilicates comprise ground silicate minerals, such as but not limited to, sillimanite; Al ₂SiO ₅; mullite; 3Al ₂O ₃.2SiO ₂; kyanite; and Al ₂SiO ₅.

The ring silicates group comprises silicate minerals, such as but not limited to, cordierite and Al ₃ (Mg, Fe) ₂ [Si ₄AlO ₁₈] . The chain silicates group comprises ground silicate minerals, such as but not limited to, wollastonite and Ca [SiO ₃] .

The sheet silicates group comprises silicate minerals, such as but not limited to, mica;

K ₂AI ₁₄ [Si ₆Al ₂O ₂₀] (OH) ₄; pyrophyllite; Al ₄ [Si ₈O ₂₀] (OH) ₄; talc; Mg ₆ [Si ₈O ₂₀] (OH) ₄; serpentine for example, asbestos; Kaolinite; Al ₄ [Si ₄O ₁₀] (OH) ₈; and vermiculite.

Such additional fillers may also be hydrophobically treated in the same manner as component (b) as described above. When present the non-reinforcing fillers tend to be used to replace some of component (b) , hence when component (b) the reinforcing filler is precipitated calcium carbonate and a non-reinforcing filler is also present in the composition the total amount of precipitated calcium carbonate and non-reinforcing filler will still be no more than the upper limit 60 wt. %of the composition. In one embodiment of the composition when component (b) is precipitated calcium carbonate the composition also comprises ground calcium carbonate. When present the non-reinforcing filler may be present in an amount of from greater than zero to 20 wt. %of the composition.

Pigments

The one-part hot porous surface condensation curable silicone composition as described herein may further comprise one or more pigments and/or colorants which may be added if desired. The pigments and/or colorants may be coloured, white, black, metal effect, and luminescent e.g., fluorescent and phosphorescent. Pigments are utilized to colour the composition as required. Any suitable pigment may be utilized providing it is compatible with the composition herein. In one-part hot porous surface condensation curable silicone compositions pigments and/or coloured (non-white) fillers e.g., carbon black may be utilized in the catalyst package to colour the end sealant product.

Suitable white pigments and/or colorants include titanium dioxide, zinc oxide, lead oxide, zinc sulfide, lithophone, zirconium oxide, and antimony oxide.

Suitable non-white inorganic pigments and/or colorants include, but are not limited to, iron oxide pigments such as goethite, lepidocrocite, hematite, maghemite, and magnetite black iron oxide, yellow iron oxide, brown iron oxide, and red iron oxide; blue iron pigments; chromium oxide pigments; cadmium pigments such as cadmium yellow, cadmium red, and cadmium cinnabar; bismuth pigments such as bismuth vanadate and bismuth vanadate molybdate; mixed metal oxide pigments such as cobalt titanate green; chromate and molybdate pigments such as chromium yellow, molybdate red, and molybdate orange; ultramarine pigments; cobalt oxide pigments; nickel antimony titanates; lead chrome; carbon black (when present, carbon black will function as both a non-reinforcing filler and colorant) ; lampblack, and metal effect pigments such as aluminium, copper, copper oxide, bronze, stainless steel, nickel, zinc, and brass.

Suitable organic non-white pigments and/or colorants include phthalocyanine pigments, e.g. phthalocyanine blue and phthalocyanine green; monoarylide yellow, diarylide yellow, benzimidazolone yellow, heterocyclic yellow, DAN orange, quinacridone pigments, e.g. quinacridone magenta and quinacridone violet; organic reds, including metallized azo reds and nonmetallized azo reds and other azo pigments, monoazo pigments, diazo pigments, azo pigment lakes, β-naphthol pigments, naphthol AS pigments, benzimidazolone pigments, diazo condensation pigment, isoindolinone, and isoindoline pigments, polycyclic pigments, perylene and perinone pigments, thioindigo pigments, anthrapyrimidone pigments, flavanthrone pigments, anthanthrone pigments, dioxazine pigments, triarylcarbonium pigments, quinophthalone pigments, and diketopyrrolo pyrrole pigments.

Typically, the pigments and/or colorants, when particulates, have average particle diameters in the range of from 10 nm to 50 μm, preferably in the range of from 40 nm to 2 μm. The pigments and/or colorants when present are present in the range of from 2, alternatively from 3, alternatively from 5 to 20 wt. %of the composition.

Rheology modifiers

Rheology modifiers which may be incorporated in one-part hot porous surface condensation curable silicone composition include silicone organic co-polymers such as those described in EP0802233 based on polyols of polyethers or polyesters; non-ionic surfactants selected from the group consisting of polyethylene glycol, polypropylene glycol, ethoxylated castor oil, oleic acid ethoxylate, alkylphenol ethoxylates, copolymers or ethylene oxide and propylene oxide, and silicone polyether copolymers; as well as silicone glycols. For some systems these rheology modifiers, particularly copolymers of ethylene oxide and propylene oxide, and silicone polyether copolymers, may enhance the adhesion to substrates, particularly plastic substrates.

Adhesion Promoters

The one-part hot porous surface condensation curable silicone composition as hereinbefore described may also comprise an aminosilane adhesion promoter having two or three hydroxyl or alkoxy groups per molecule. The aminosilane adhesion promoter having two or three hydroxyl or alkoxy groups per molecule may comprise aminopropyltriethoxysilane or aminopropyltrimethoxysilane or may comprise:

R ¹⁰ _k (R ¹¹O) _3-kSi-Z ¹-N (H) - (CH ₂) _m -NH ₂ in which R ¹⁰ is an alkyl group containing from 1 to 10 carbon atoms; each R ¹¹ may be the same or different and is H or R ¹⁰, Z ¹ is a linear or branched alkylene group having from 2 to 10 carbon atoms, m is from 2 to 10 and k is zero or 1.

R ¹⁰ is an alkyl group containing from 1 to 10 carbon atoms, alternatively R ¹⁰ is an alkyl group containing from 1 to 6 carbon atoms, alternatively, R ¹⁰ is a methyl or ethyl group. Each R ¹¹ may be the same or different and is each R ¹¹ may be the same or different and is H or R ¹⁰, alternatively each R ¹¹ is R ¹⁰. In one alternative all R ¹¹ groups are the same. When the R ¹¹ groups are the same, it is preferred that they are methyl or ethyl groups. Z ¹ is a linear or branched alkylene group having from 2 to 10 carbons, alternatively from 2 to 6 carbons, for example Z ¹ may be a propylene group, a butylene group or an isobutylene group. There may be from 2 to 10 m groups, in one alterative m may be from 2 to 6, in another alternative m may be from 2 to 5, in a still further alternative m may be 2 or 3, alternatively m is 2.

Specific examples include but are not limited to aminopropyltriethoxysilane, aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminoisobutylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -2-aminoethylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminoisobutylethyldimethoxysilane, N- (2-aminoethyl) -2-aminoethylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl) -2-aminoethylmethyldiethoxysilane, N- (2-aminoethyl) -3-aminoisobutylethyldiethoxysilane, N- (2-aminoethyl) -2-aminoethylmethyldiethoxysilane, N- (2-aminoethyl) -3-aminopropylmethylmethoxyethoxysilane, N- (2-aminoethyl) -2-aminoethylmethylmethoxyethoxysilane, N- (2-aminoethyl) -3-aminoisobutylethylmethoxyethoxysilane, N- (2-aminoethyl) -2-aminoethylmethylmethoxyethoxysilane, N- (2-aminopropyl) -3-aminoisobutylmethyldimethoxysilane, N- (2-aminopropyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminopropyl) -2-aminoethylmethyldimethoxysilane, N- (2-aminopropyl) -3-aminoisobutylethyldimethoxysilane, N- (2-aminopropyl) -2-aminoethylmethyldimethoxysilane, N- (2-aminopropyl) -3-aminopropylmethyldiethoxysilane, N- (2-aminopropyl) -2-aminoethylmethyldiethoxysilane, N- (2-aminopropyl) -3-aminoisobutylethyldiethoxysilane, N- (2-aminopropyl) -2-aminoethylmethyldiethoxysilane, N- (2-aminopropyl) -3-aminopropylmethylmethoxyethoxysilane, N- (2-aminopropyl) -2-aminoethylmethylmethoxyethoxysilane, N- (2-aminopropyl) -3-aminoisobutylethylmethoxyethoxysilane, N- (2-aminopropyl) -2-aminoethylmethylmethoxyethoxysilane as well as their trialkoxy, especially trimethoxy and triethoxy equivalents (where k is zero) such as 3- (2-aminoethyl) -aminopropyltriethoxysilane, 3- (2-aminoethyl) -aminopropyltrimethoxysilane, N- (3- (Trimethoxysilyl) propyl) butylamine and Bis (trimethoxysilylpropyl) amine.

The adhesion promoter when present is present in an amount of from 0.1 to 3.75%by weight of the composition, alternatively, in an amount of 0.1-2.5 %by weight of the composition, alternatively, in an amount of 0.1-2.0 %by weight of the composition, alternatively, in an amount of 0.2 to 1.0 %by weight of the composition.

Tin (iv) Catalyst

Preferably the only condensation cure catalyst present in the one-part hot porous surface condensation curable silicone composition is component (f) described above. However, if desired a tin (iv) catalyst may optionally be provided in the composition. When present the tin (iv) catalyst may be any suitable tin (iv) based condensation cure catalyst. Examples of suitable tin (iv) based catalysts include tin triflates, dialkyltin compounds, selected from dimethyltin di-2-ethylhexanoate, dimethyltin dilaurate, di-n-butyltin diacetate (DBTDA) , di-n-butyltin di-2-ethylhexanoate, dimethyltin dineodecanoate (DMTDN) , dioctyltin dineodecanoate (DOTDN) , di-n-butyltin dicaprylate, di-n-butyltin di-2, 2-dimethyl octanoate, di-n-butyltin octanoate, di-n-butyltin dilaurate (DBTDL) , di-n-butyltin distearate, di-n-butyltin dimaleate, di-n-butyltin dioleate, di-n-octyltin di-2-ethylhexanoate, di-n-octyltin di-2, 2-dimethyl octanoate, di-n-octyltin dimaleate, di-n-octyl tin dilaurate (DOTDL) , di-n-butyl tin oxide, carbomethoxyphenyl tin trisuberate, tin butyrate, butyltintri-2-ethylhexoate, tin naphthenate, isobutyltintriceroate, tin octoate, triethyltin tartrate and di-n-octyl tin oxide. When present said tin (iv) based condensation catalyst may be present in an amount of from 0.001 to 0.1 %inclusive by weight (wt. %) of the composition. It was found that whilst not essential, the use of a small amount of a tin (iv) catalyst could be utilised to speed up cure e.g., tack free time (TFT) if desired. That said, in one embodiment no tin (iv) catalyst is present in the composition.

UV and/or light stabilizers

UV and/or light stabilizers may include, for the sake of example include benzotriazole, ultraviolet light absorbers and/or hindered amine light stabilizers (HALS) such as the

product line from Ciba Specialty Chemicals Inc.

Biocides

Biocides may additionally be utilized in the composition if required. It is intended that the term "biocides" includes bactericides, fungicides and algicides, and the like. Suitable examples of useful biocides, which may be utilized in compositions as described herein, include, for the sake of example:

Carbamates such as methyl-N-benzimidazol-2-ylcarbamate (carbendazim) and other suitable carbamates, 10, 10'-oxybisphenoxarsine, 2- (4-thiazolyl) -benzimidazole, N- (fluorodichloromethylthio) phthalimide, diiodomethyl p-tolyl sulfone, if appropriate in combination with a UV stabilizer, such as 2, 6-di (tert-butyl) -p-cresol, 3-iodo-2-propinyl butylcarbamate (IPBC) , zinc 2-pyridinethiol 1-oxide, triazolyl compounds and isothiazolinones, such as 4, 5-dichloro-2- (n-octyl) -4-isothiazolin-3-one (DCOIT) , 2- (n-octyl) -4-isothiazolin-3-one (OIT) and n-butyl-1, 2-benzisothiazolin-3-one (BBIT) . Other biocides might include for example Zinc Pyridinethione, 1- (4-Chlorophenyl) -4, 4-dimethyl-3- (1, 2, 4-triazol-1-ylmethyl) pentan-3-ol and/or 1- [ [2- (2, 4-dichlorophenyl) -4-propyl-1, 3-dioxolan-2-yl] methyl] -1H-1, 2, 4-triazole.

The fungicide and/or biocide may suitably be present in an amount of from 0 to 0.3wt. %of the composition and may be present in an encapsulated form where required such as described in EP2106418.

Hence, the one-part hot porous surface condensation curable silicone composition which is suitable for application on porous substrates at a temperature of at least 40℃ described herein may comprise (a) an organopolysiloxane polymer having at least two hydroxyl or hydrolysable groups per

molecule of the formula

X _3-nR _nSi-Z- (R ¹ _ySiO _(4-y) _/2) _z –SiR ¹ ₂ -Z-Si-R _nX _3-n (1)

n is 0 or 1, y is 0, 1 or 2, and preferentially 2 and z is an integer such that said organopolysiloxane polymer has a viscosity of from 10,000 to 150,000 mPa. s at 25℃, alternatively from 30,000 to 140,000mPa. s at 25℃, in accordance with Corporate test method CTM 0050, which is publicly available, and which is based on ASTM D 1084-16 method B, using a Brookfield HBDV-III Ultra Rheometer equipped with a cone-and-plate geometry using spindle 52, in an amount of from 30 to 90 wt. %of the composition, alternatively 35 to 75%, alternatively 35 to 60 wt. %of the composition;

(b) one or more reinforcing fillers selected from precipitated silica or fumed silica in each case having a surface area of at least 50 m ²/g in accordance with the BET method (ISO 9277: 2010) or precipitated calcium carbonate having a surface area of at least 15 m ²/g measured in accordance with the BET method (ISO 9277: 2010) ; in an amount of from 2.5 to 60 %by weight (wt. %) of the composition, wherein when the selected fillers are precipitated silica and/or fumed silica or a combination thereof the inorganic fillers (b) are present in a range of from about 5.0 to 35 wt. %of the composition, alternatively of from 5 to 30 wt. %of the composition, alternatively of from 5 to 25 wt. %of the composition and wherein when the selected filler is precipitated calcium carbonate, the composition will tend to include a larger wt. %of the composition, e.g. from 25 to 60 wt. %, alternatively of from 30 to 60 wt. %of the composition, alternatively of from 35 to 55 wt. %of the composition;

R ³ ₂ –Si –R ⁴ ₂

Wherein each group R ³ may be the same or different and is a hydrolysable group selected from alkoxy or acetoxy groups and each R ⁴ group is the same or different and independently represents an alkyl group having from 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aryl group or a fluorinated alkyl group present; in a range of from 1 to 10 wt. %of the composition, alternatively from 1.25 to 7.5 weight %of the composition, alternatively from 1.5 to 4.0 weight %of the composition;

(d) Tetra-n-propoxysilane in an amount of from 0.40 to 3.5 wt. %of the composition, alternatively 0.40 to 3.0 wt. %of the composition, alternatively 0.40 to 2.5 wt. %of the composition, alternatively 0.40 to 2.5 wt. %of the composition, alternatively 0.50 to 2.0 wt. %of the composition;

(e) (a’) , the 1, 3, 5-tris (trialkoxysilylalkyl) isocyanurate

(e) (b’) a siloxane oligomer of the structure

Si- ( (O-Si (CH ₃) ₂) _n’- (R ⁷ –Si (CH ₃) ₂ –O-Si (CH ₃) ₂) _z’–R ⁷ –Si (OR ⁸) ₃) ₄; where each R ⁷ may be the same or different and may be the same as R ⁵ and each R ⁸ may be the same or different and may be the same as R ⁶, n’ is an integer and z’ is zero or 1; or

(e) (c’) a siloxane oligomer of the structure

where again R ⁷, R ⁸ n’ and z’ are as defined above and R ⁹ may be the same as R ⁸; present in an amount of from 0.1 to 5 wt. %of the composition, present in an amount of from 0.1 to 4 wt. %of the composition, alternatively in an amount of from 0.1 to 2.5 wt. %of the composition, alternatively in an amount of from 0.1 to 1.5 wt. %of the composition, alternatively in an amount of from 0.1 to 1.0 wt. %of the composition; and

(f) a catalyst comprising a titanate-based compound, a zirconate-based compound or a mixture thereof in an amount of from 0.05 wt. %to 1.5 wt. %of the composition, alternatively in an amount of from 0.05 wt. %to 1.25 wt. %of the composition, alternatively in an amount of from 0.1 wt. %to 1.0 wt. %of the composition, alternatively in an amount of from 0.1 wt. %to 0.75 wt. %of the composition.

The one-part hot porous surface condensation curable silicone composition may comprise any combination of the above providing that the total composition of ingredients (a) to (f) together with any other optional ingredients included in the composition has a value of 100 wt. %of the composition. It will be appreciated that component (d) and component (e) are different.

Furthermore, as previously indicated components (c) + (d) + (e) are present cumulatively in the one-part hot porous surface condensation curable silicone composition in a range of from 1.5 to 18.5 wt. %of the composition. Alternatively, components (c) + (d) + (e) may be present cumulatively in a range of from 1.5 to 10 wt. %of the composition; alternatively, components (c) + (d) + (e) may be present cumulatively in a range of from 2.0 to 7.5 wt. %of the composition; alternatively, components (c) + (d) + (e) may be present cumulatively in a range of from 2.5 to 7.5 wt. %of the composition.

There is also provided a method for sealing a hot porous substate wherein the substrate is at a temperature of at least 40℃ comprising the steps of

(i) applying a one-part hot porous surface condensation curable silicone composition as described above on to the hot porous substrate having a temperature of at least 40℃, and

(ii) curing the said composition.

Alternatively, to obtain a silicone sealant bonded to a surface of the hot porous substrate there is provided a method of bonding silicone sealant to a hot porous substrate at a temperature of at least 40℃., comprising the steps of preparing a one-part hot porous surface condensation curable silicone composition as hereinbefore described, contacting a surface of a hot porous substrate at a temperature of at least 40℃. with the one-part hot porous surface condensation curable silicone composition and curing said one-part hot porous surface condensation curable silicone composition. The one-part hot porous surface condensation curable silicone composition as described above may be prepared by mixing all the ingredients together. Preferably once mixed, unless to be used immediately, the composition is sealed in one or more moisture-tight containers and is stored. In one embodiment filler (b) and/or pigment when present is/are first mixed into the polymer (a) , optionally, if required in combination with a hydrophobic treating agent so that the filler and optional pigment may be hydrophobically treated in situ during the mixing into the polymer. Once the filler is adequately mixed into the polymer (and if desired has been hydrophobically treated) then the remaining components are added in any suitable order to make the complete composition.

For example, in one method, when optional pigment is present the process for making the one-part hot porous surface condensation curable silicone composition may comprise the following steps: -

1) Gradually add the or each reinforcing filler (b) and any non-reinforcing filler, when present, and, if required hydrophobing filler treating agent into the polymer (a) for a predetermined time, under vacuum if deemed necessary; to form a polymer base;

2) Premix components (c) , (d) , (e) and (f) to form premix 1;

3) premix 1 was then added into the polymer base and is mixed into the base, under vacuum if deemed necessary;

4) Finally leave the mixture to cool to less that 40℃, release the vacuum and, if to be stored package the final composition.

When optional pigment is to be used the pigment may be introduced prior to the filler (s) or simultaneously with the fillers resulting in a pigmented polymer base after the completion of step 1 above. Optional ingredients such as adhesion promoter (s) may also be added into premix 1. However, when the optional tin catalyst is to be included in the composition a second pre-mix may be prepared comprising e.g., optional ingredients such as adhesion promoter and the optional tin (iv) catalyst. When two premixes are desired these may be split so that components (d) , (e) (f) and part of (c) are mixed together in one premix, e.g. premix 1a and the remainder of component (c) , optional adhesion promoter and tin (iv) catalyst are mixed together in a second premix, premix 2 and the two premixes can be introduced and mixed into the composition in any order, for example premix 1a may be added first, mixed in and the premix 2 can be added and mixed in to complete the composition.

Bubbling on stone, marble, brick, concrete, cement and other cementitious substrates, particularly stone substrates during summer season is a common issue for one-part room temperature vulcanisable (RTV) silicone compositions, particularly after storage, containing alkoxy terminated polymers (a) and titanate/zirconate catalysts (f) . When standard one-part room temperature vulcanisable (RTV) silicone compositions, with alkoxy terminated polymers and titanate and/or zirconate catalysts, are applied onto porous surfaces which are at a temperature lower than 40℃some bubbles are formed. However, the generation of bubbles is far more marked and consequently far more easily observed when the substrates are at temperatures of 40℃ or more, usually due to the direct sunlight. Without being bound to current theories it is thought that the bubbling may be caused by the generation of alcohols, especially methanol during the cure process at hot temperatures with the porous nature of the substrate acting as some form of accelerator with the pores of the porous substrates acting as nucleation points for the formation of bubbles which are then trapped during cure within the body of the sealant, not least because of the process by which such compositions cure, i.e. with the initial formation of a skin preventing the escape of the bubbles especially as at elevated temperatures cure will be accelerated causing the skin to form quicker than when the sealant cures at room temperature or thereabouts.

The one-part hot porous surface condensation curable silicone composition as described in the present disclosure however may be applied on to hot porous substrates having a temperature of at least 40℃ by any suitable means such as by extrusion, coating, injection, knifing and rolling, typically dependent on the viscosity and ability to flow on the substrate surface. Irrespective of the means of application, it was found that either no bubbles were formed or comparatively much fewer bubbles were formed at the interface between the porous substrate surface and the sealant applied when compared to standard one-part room temperature vulcanisable (RTV) silicone compositions. The reduction in the number and size of bubbles in the cured silicone sealant compared to a standard RTV silicone sealant is significant and as such is consequently of significant benefit to the construction industry in hot countries in which substrates regularly reach temperatures of over 40℃during the hottest parts of the day due to the heat from the sun etc. because the significant bubble formation with regards standard sealants has proven to be a major issue for the construction industry because it leads to surface blistering between the curing/cured sealant and the substrate surface resulting in poor adhesion therebetween. These bubbles are unacceptable and increase the volume of the cured product by as much as two or three times compared to the product not cured on a hot porous substrate.

An additional advantage of the present one-part hot porous surface condensation curable silicone compositions was that it allowed the user to have an increased working time compared to standard sealant compositions which tend to cure very quickly at the temperatures concerned because after said one-part hot porous surface condensation curable silicone composition is applied to the hot porous substrate, it is exposed to atmospheric moisture causing it to cure and adhere to the initially hot porous substrate surface.

There is also provided herein an elastomeric sealant material which is the cured product of the one-part hot porous surface condensation curable silicone composition as hereinbefore described. Alternatively, there is provided a sealant bonded to a hot porous substrate at a temperature of at least 40℃ obtained or obtainable by preparing a one-part hot porous surface condensation curable silicone composition as hereinbefore described, contacting a surface of a hot porous substrate at a temperature of at least 40℃. with the one-part hot porous surface condensation curable silicone composition and curing said one-part hot porous surface condensation curable silicone composition. Not only did the resulting elastomeric sealant material adhere to the hot porous substrates with a significantly reduced level of trapped bubbles, but it additionally showed high movement capability passing ASTM C920 50%, superior adhesion on various substrates in accordance with ASTM C794 and very good non-staining performance given it passed ASTM C1248.

Hence, given the high movement capability, the one-part hot porous surface condensation curable silicone composition herein may be further managed to engineer a low modulus one-part hot porous surface condensation curable silicone composition. Low modulus silicone sealant compositions are preferably “gunnable” i.e., they have a suitable extrusion capability and given the resulting sealant imparts a movement capability to the post-cured sealant material of greater than 25 %and indeed in one exceptional case greater than 50%as measured in accordance with ASTM C920 50%.

Hence, the one-part hot porous surface condensation curable silicone composition suitable for application on porous substrates at a temperature of at least 40℃ as hereinbefore described may be a gunnable sealant composition used for

(i) space/gap filling applications;

(ii) seal applications, such as sealing the edge of a lap joint in a construction membrane; or

(iii) a stain-resistant weather sealing sealant;

(iv) adhering at least two substrates together; and/or

(v) a laminating layer between two substrates to produce a laminate of the first substrate, the sealant product and the second substrate.

In the case of (v) above when used as a layer in a laminate, the laminate structure produced is not limited to these three layers. Additional layers of cured sealant and substrate may be applied. The layer of gunnable sealant composition in the laminate may be continuous or discontinuous. In the case of the one-part hot porous surface condensation curable silicone composition as hereinbefore described, there is provided a method for filling a space between two substrates so as to create a seal therebetween, comprising:

a” ) providing a one-part hot porous surface condensation curable silicone composition as hereinbefore described, and either

b” ) applying the one-part hot porous surface condensation curable silicone composition on to a first substrate, and bringing a second substrate in contact with the silicone composition that has been applied to the first substrate wherein either or both of said substrates are porous substrates at a temperature of at least 40℃, or

d” ) curing same.

A one-part hot porous surface condensation curable silicone composition as hereinbefore described suitable for application on porous substrates at a temperature of at least 40℃ may be applied on to any suitable substrate but given the application is particularly designed for application on substrates such as stone, marble, brick, concrete, cement and other cementitious substrates combinations thereof, and combinations with other non-porous building materials such as metals e.g. aluminium and steel and glass which can reach temperatures of at least 40℃ in hot countries during the summer period when it is hottest as a stain-resistant weather sealing sealant material for construction and the like applications.

The one-part hot porous surface condensation curable silicone composition as hereinbefore described may therefore provide a silicone sealant which may be of a low-modulus type having high movement capabilities. Furthermore, the composition herein is clear, i.e., transparent and/or translucent and is non-staining (clean) on construction substrates such as said granite, limestone, marble, masonry and glass which can reach temperatures of at least 40℃ in hot countries during the summer period when it is hottest.

The Low modulus nature of the silicone elastomer produced upon cure of the one-part hot porous surface condensation curable silicone composition when designed to be low modulus described herein makes the elastomer effective at sealing joints which may be subjected to movement for any reason, because compared to other cured sealants (with standard or high modulus) lower forces are generated in the cured sealant body and transmitted by the sealant to the substrate/sealant interface due to expansion or contraction of the joint enabling the cured sealant to accommodate greater joint movement without failing cohesively or interfacially (adhesively) or cause substrate failure.

There is also provided a use of the aforementioned one-part hot porous surface condensation curable silicone composition as a sealant suitable for application on porous substrates at elevated temperatures, i.e., at greater than 40℃ such as stone, marble, brick, concrete, cement and other cementitious substrates combinations thereof as well as in combinations with other non-porous building materials in the facade, insulated glass, window construction and construction fields in hot countries. The porous substrates may be particularly preferred for use on stone

as a weather seal.

Examples

A series of examples are now provided.

All viscosity measurements were taken at 25℃ unless otherwise indicated. Unless otherwise indicated, all viscosities in the examples were measured in accordance with corporate test method CTM 0050, which is publicly available, and which is based on ASTM D 1084-16 method B, using a Brookfield HBDV-III Ultra Rheometer equipped with a cone-and-plate geometry using spindle 52. Normally bubbling occurs when alkoxy sealant compositions are applied onto the porous substrates (e.g., stone, marble, brick, concrete, cement and other cementitious substrates etc. ) during summer (hot) seasons in countries where the temperature for the majority of the working day will render exterior construction surfaces at temperatures of at least 40℃. The bubbling particularly occurs to sealant composition which have been stored before use. To mimic such conditions stone test substates were heated in an oven for at least 30 min before sealant application and unless otherwise indicated all stone test samples were tested when their surface was a temperature of above 40℃, typically 50℃ unless otherwise indicated.

The compositions of comparative 1 (C. 1) and Examples 1 to 4 (Ex. 1 to Ex. 4) are provided below in Table 1.

Table 1: Formulation of Comparative Example (C. 1) and Inventive Examples (Ex. 1 to 4) in wt. ％

Material	C. 1	Ex. 1	Ex. 2	Ex. 3	Ex. 4
Polymer	44.97	44.97	44.92	44.67	44.22
Precipitated calcium carbonate (PCC) filler	32	32	32	32	32
Ground calcium carbonate (GCC) filler	18	18	18	18	18
Vinylmethylldimethoxysilane (VMDM)	3.5	2	2.8	3.2	3.8
Catalyst 1	0.87	0.87	0.87	0.87	0.87
Bis (lauroyloxy) dioctyltin (DOTDL)			0.05
Tris (3-trimethoxysilylpropyl) isocyanurate	0.5	0.5	0.5	0.5	0.5
Tetra-n-propoxysilane (TPOS)		1.5	0.7	0.6	0.45
3- (2-aminoethyl) -aminopropyltrimethoxysilane	0.16	0.16	0.16	0.16	0.16
Total	100	100	100	100	100

In Table 1:

Polymer: The polymer was a (MeO) ₃ Si-CH ₂-CH ₂-terminated polydimethylsiloxane polymer a viscosity of approximately 65,000 mPa. s at 25℃;

Precipitated calcium carbonate (PCC) filler: The PCC was an ultrafine precipitated calcium carbonate coated with fatty acids sold under the trade name Hakuenka ^TM CCR -S by Shiraishi Kogyo Kaisha, Ltd;

Ground calcium carbonate (GCC) : The GCC was Omyacarb ^TM 5 T which is a fine, coated ground calcium carbonate (GCC) commercially available from OMYA AG; and

Catalyst 1: Catalyst 1 was Tyzor ^TM PITA SM which is an 80: 20 wt. %mixture of Diisopropoxy-bisethylacetoacetatotitanate and methyltrimethoxy silane and is commercially available from Dorf Ketal Speciality Catalysts LLC of Texas USA.

Each composition in Table 1 was prepared using the following process:

The examples and comparative examples were prepared based on a 5kg sample using a 10 litre Turello mixer as follows:

1) The polymer and pigment were first introduced into the mixer and were mixed together at 400 rpm for 5 min;

2) The PCC and GCC fillers were then gradually introduced into the mixer at an increased mixing speed of 800rpm, for 8 min at full vacuum, after which the mixture in the mixer was scraped down and the mixture was mixed for a further 7 minutes to form a pigmented silicone polymer base;

3) A premix 1 was prepared separately by mixing the tris (3-trimethoxysilylpropyl) isocyanurate, TPOS and of the VMDM together with the titanate catalyst;

3a) in the case of example (2) when a tin catalyst is present, the VMDM is split between two premixes premix 1 as above and premix 2 in which the remaining VMDM was mixed together with the 3- (2-aminoethyl) -aminopropyltriethoxysilane and DOTDL to form a second premix, premix 2; when the tin catalyst is not present but the adhesion promoter is, then the adhesion promoter is introduced into premix 1;

4) The premix 1 was then added into the pigmented silicone polymer base resulting from step 2 and was mixed therewith at 400rpm for a further 5 mins before premix 2 was added (if required) , after which the mixing was increased to 800 rpm and mixing continued under a vacuum of -70 kPa for 20 min;

5) The mixing was then decreased and the vacuum increased to -80 kPa for 5min after which once the mixture had cooled down sufficiently the final mixture was introduced into cartridges for storage.

Samples of the sealant compositions depicted in Table 1 above were aged at a temperature of 50℃for two weeks in the cartridges in which they were packaged before being applied on to granite substrate samples which were at a temperature of approximately 50℃ at the time of sealant application. The aging period was chosen as an accelerated test to mimic the sealant shelf life. The bubbling issue mainly occurs when sealant stored over 5-6 months. All fresh samples showed no substantial bubbling issue; thus, the aged samples were used for the validation of mitigation methods or compositions.

The results are provided in Table 2 below.

Table 2: Bubbling status check: wet sealant aged at 50℃ for 2 weeks prior to application on 50℃granite substrate at approximately 50℃

The amount of bubbles present in the cured sealant was visually assessed on a scale of from 1 (no or minimal bubbling observed) to 5 wherein significant bubbling was observed which resulted in poor adhesion between the granite substrate and the cured sealant. The scoring criteria for the bubbling status is as follows: -

1 = no bubbling observed

2 = very minimal bubbling, no impact on adhesion

3 = some bubbling, may have negative impact on adhesion

4 = obvious bubbling observed, negatively impact adhesion

5 = very significant bubbling observed, almost no adhesion (easily peeling off by hand)

It was found that in the case of C. 1 many bubbles were observed and it was later found that when such a high level of visually evident bubbles were present, it had a dramatic effect on the adhesion of the cured sealant to the granite substrate with poor adhesion observed. Ex. 1, 2 and 3 gave excellent results with substantially no bubbles observed and good adhesion between the granite substrate and the cured sealant. Ex. 4 which had slightly less TPO present did have a small number of bubbles evident, but they were minimal and their existence did not appear to have any impact on the adhesion between the substrate and the cured sealant.

The unaged physical properties of the comparative example and four examples were also assessed. Each sealant test piece or the like was prepared in accordance with the relevant test methodology and testing was undertaken to assess a variety of physical properties for each of C. 1 and Ex. 1 to 4. The results are provided in Table. 3a and the methodology utilised is provided below.

Table 3a: Unaged Physical Properties of Comparative Example (C. 1) and Inventive Examples (Ex. 1 to 4)

General performance	C. 1	Ex. 1	Ex. 2	Ex. 3	Ex. 4
Tack free time (TFT) min	29	170	31	58	50
Extrusion rate (g/min. )	146	91	100	135	144
Cure in depth (CID) (1 day) , mm	1.44	2.08	1.92	1.88	1.6
Tensile strength (MPa)	2.53	2.18	2.37	2.27	2.46
Elongation at break (%)	716	407	551	594	644
Shore A durometer	32.45	41.30	41.10	37.95	38

The test methods used to generate the results in Table 2a are provided below: -

Tack free time (TFT) was measured via polyethylene contact following Dow’s corporate test method (CTM) 0095 with the results depicted measured in minutes.

Extrusion Rate was measured following Dow’s CTM 0364. It is designed to determine the rate at which a material will extrude through a standard nozzle under a specified pressure and is based on MIL (Military specification) MIL-S-8802D. Results are provided in g/min.

Cure in depth (CID) was measured following Dow’s CTM 0663 and measures the depth of cure of a sample by measuring how far below the surface a curing material has hardened in a specified time. Results were taken after 1 day and are provided in mm.

Tensile Strength was measured following Dow’s CTM 0137 A which is based on ASTM D 412 and used die C. Results were provided in MPa.

Elongation at Break was measured following Dow’s CTM 0137 A which is based on ASTM D 412 and used die C. Results were provided in %.

Shore A Durometer was measured following Dow’s CTM 099 which is based on ASTM D 2240. All the above corporate test (CTM) methods are available to the public from Dow Silicones Corporation upon request.

It was found that in each case the properties of the sealants prepared using the compositions defined in Table were satisfactory. However, it can be seen that increased levels of TPOS lead to slower TFT. Whilst this is not an issue in most instances it was found that the TFT could be faster if a small amount of a Tin (iv) catalyst were added into the composition.

Following on from the above samples of C. 1 and Ex. 3 were aged to assess physical properties of the sealant materials after aging. Aging was carried out over 2 weeks at 50℃ and over 4 weeks at 50℃. The results thereof are depicted in Tables 3b and 3c respectively.

Table 3b: Physical Properties of C. 1 and Ex. 3 after aging for a period of 2 weeks at 50℃

	C. 1	Ex. 3
Tack free time (TFT) min	60	58
Extrusion rate (g/min. )	152	135
Tensile strength (MPa)	1.72	2.14
Elongation at break (%)	998	860
Shore A durometer	21.65	31.65

Table 3c: Physical Properties of C. 1 and Ex. 3 after aging for a period of 4 weeks at 50℃

	C. 1	Ex. 3
Tack free time (TFT) min	67	55
Extrusion rate (g/min. )	165.5	151
Tensile strength (MPa)	1.08	1.97
Elongation at break (%)	998	751
Shore A durometer	19.1	30.60

Compared with C. 1, Ex. 3 showed much better aging performance.

C. 1 and Ex. 3 were also compared with respect to a series of tests from Chinese National Standard GB/T 23261-2009 –Building sealants for stone and the results are depicted in Table 4 below.

Table 4: physical properties testing in accordance with Chinese National Standard GB/T 23261-2009

NF = No failure, WI = water immersion.

The elastic recovery test was undertaken on a sample having been cured at room temperature for 28 days. The sample was extended to a 100%extension and then released and the elastic recovery was determined.

In the first adhesion test, an Instron tensile tester (do you know the model) was used to determine whether samples suffered a cohesive failure (CF) or adhesive failure (AF) when extended to 100%after 28days curing at standard conditions (23℃ and 50%relative humidity) . In the third adhesion test samples were cured for 28 days, then put into water for 4 days before being removed from the water and left at room temperature for 24hrs at standard conditions before undergoing tensile strength testing using the Instron tensile tester to determine if the sample underwent any cohesive failure or adhesive failure.

Adhesive failure (AF) is interfacial bond failure between an adhesive and an adherend. Cohesive failure occurs when a fracture allows a layer of adhesive to remain on both surfaces. Hence, in Table 4 Cohesive failure (CF) is observed when the sealant itself breaks without detaching from the substrate. In some cases, a mixed failure mode may be observed; that is some areas peel-off (i.e., AF) while some remain covered with coating (i.e., CF) . In such cases, the portions of surface displaying CF (%CF) .

A more detailed assessment of the adhesion ability of C. 1 and Ex. 3 was undertaken with respect to several different substrates in accordance with ASTM C794 and the results are provided in Table 5 below.

Table 5: Peeling adhesion comparison of C. 1 and Ex. 3 in accordance with ASTM C794 with the results provided in terms of %cohesive failure.

The sealant composition in accordance with this disclosure showed good adhesion on various substrates.

In addition, the developed one-part alkoxy clean sealant also showed high movement capability passing both ASTM C920 50%and GB/T 23261 50HM) .

Claims

A one-part hot porous surface condensation curable silicone composition which is suitable for application on porous substrates of at least 40℃ comprising the following components: -

(a) an organopolysiloxane polymer having at least two hydroxyl or hydrolysable groups per molecule of the formula

X _3-nR _nSi-Z- (R ¹ _ySiO _(4-y) /2) _z –SiR ¹ ₂ -Z-Si-R _nX _3-n (1)

in which each X is independently a hydroxyl group or an alkoxy group, each R is an alkyl, alkenyl or aryl group, each R ¹ is an X group, alkyl group, alkenyl group or aryl group and Z is a divalent organic group;

n is 0 or 1, y is 0, 1 or 2, and preferentially 2 and z is an integer such that said organopolysiloxane polymer has a viscosity of from 10,000 to 150,000 mPa.s at 25℃, in an amount of from 30 to 90 wt. %of the composition;

(b) one or more reinforcing fillers selected from precipitated silica, fumed silica or precipitated calcium carbonate;

(c) a silane compound having two hydrolysable groups per molecule of the formula

R ³ ₂ –Si –R ⁴ ₂

Wherein each group R ³ may be the same or different and is a hydrolysable group selected from alkoxy or acetoxy groups and each R ⁴ group is the same or different and independently represents an alkyl group having from 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aryl group or a fluorinated alkyl group, which silane compound (c) is present in the composition in an amount of from 1 to 10 wt. %of the composition;

(d) Tetra-n-propoxysilane present in an amount of from 0.40 to 3.5 wt. %of the composition;

(e) a silicon containing compound having three or more hydrolysable groups per molecule, selected from

(e) (a’) , a 1, 3, 5-tris (trialkoxysilylalkyl) isocyanurate

(e) (b’) a siloxane oligomer of the structure

Si- ( (O-Si (CH ₃) ₂) _n’ - (R ⁷ –Si (CH ₃) ₂ –O-Si (CH ₃) ₂) _z’ –R ⁷ –Si (OR ⁸) ₃) ₄;

where each R ⁷ may be the same or different and may be the same as R ⁵ and each R ⁸ may be the same or different and may be the same as R ⁶, n’ is an integer and z’ is zero or 1; or

(e) (c’) a siloxane oligomer of the structure

R ⁹-Si- ( (O-Si (CH ₃) ₂) _n’ - (R ⁷ –Si (CH ₃) ₂ –O-Si (CH ₃) ₂) _z’ –R ⁷ –Si (OR ⁸) ₃) ₃

where again R ⁷, R ⁸ n’ and z’ are as defined above and R ⁹ may be the same as R ⁸ which silicon containing compound (e) is present in the composition in an amount of from 0.1 to 5 wt. %of the composition; and

(f) a catalyst comprising a titanate-based compound, a zirconate-based compound or a mixture thereof.
A one-part hot porous surface condensation curable silicone composition in accordance with claim 1 wherein each X and each R ³ may be the same or different but is an alkoxy group having from 1 to 6 carbons.
A one-part hot porous surface condensation curable silicone composition in accordance with any preceding claim wherein components (c) + (d) + (e) are present cumulatively in a range of from 1.5 to 10 wt. %of the composition.
A one-part hot porous surface condensation curable silicone composition in accordance with any preceding claim wherein component (e) is tris- (trimethoxysilylpropyl) isocyanurate.
A one-part hot porous surface condensation curable silicone composition in accordance with any preceding claim wherein component (b) is precipitated calcium carbonate and wherein said one-part hot porous surface condensation curable silicone composition may additionally comprise a ground calcium carbonate non-reinforcing filler.
A one-part hot porous surface condensation curable silicone composition in accordance with any preceding claim which may additionally comprise an adhesion promoter and/or a pigment.
The one-part hot porous surface condensation curable silicone composition in accordance with any preceding claim which is curable on a hot porous surface at a temperature of at least 40℃ with a reduction in bubble generation.
A method of applying a one-part hot porous surface condensation curable silicone composition to at least a hot porous substrate at a temperature of at least 40℃., comprising the steps of preparing a one-part hot porous surface condensation curable silicone composition in accordance with any one of claims 1 to 7, contacting a surface of a hot porous substrate at a temperature of at least 40℃. with the one-part hot porous surface condensation curable silicone composition and curing said one-part hot porous surface condensation curable silicone composition.
A method of applying a one-part hot porous surface condensation curable silicone composition to at least a hot porous substrate at a temperature of at least 40℃., which method is directed to filling a space between two substrates so as to create a seal therebetween, comprising:

a”) providing a one-part hot porous surface condensation curable silicone composition in accordance with any one of claims 1 to 7, and either

b”) applying the one-part hot porous surface condensation curable silicone composition to a first substrate, and bringing a second substrate in contact with the silicone composition that has been applied to the first substrate wherein either or both of said substrates are porous substrates at a temperature of at least 40℃, or

c”) filling a space formed by the arrangement of a first substrate and a second substrate wherein either or both of said substrates are porous substrates at a temperature of at least 40℃, with the one-part condensation curable room temperature vulcanisable (RTV) silicone composition and

d”) curing same.
A method of applying a one-part hot porous surface condensation curable silicone composition to at least a hot porous substrate at a temperature of at least 40℃ in accordance with claim 8 or 9 wherein the substrate (s) is or are stone, marble, brick, concrete, cement and other cementitious substrates combinations thereof, and combinations with other non-porous building materials.
A sealant bonded to a hot porous substrate at a temperature of at least 40℃ obtained or obtainable by preparing a one-part hot porous surface condensation curable silicone composition in accordance with any one of claims 1 to 7, contacting a surface of a hot porous substrate at a temperature of at least 40℃. with the one-part hot porous surface condensation curable silicone composition and curing said one-part hot porous surface condensation curable silicone composition.
An elastomeric sealant material adhered to a hot porous substrate at a temperature of at least 40℃ which elastomeric sealant material is the cured product of the one-part hot porous surface condensation curable silicone composition accordance with any one of claims 1 to 7 and which contains no or substantially no trapped bubbles.
A sealant bonded to a hot porous substrate at a temperature of at least 40℃ in accordance with claim 11 or 12 wherein said substrate is stone, marble, brick, concrete, cement and other cementitious substrates.
Use of a one-part hot porous surface condensation curable silicone composition in accordance with any one of claims 1 to 7 as a means of applying said one-part hot porous surface condensation curable silicone composition on to the hot porous substrate having a temperature of at least 40℃, whilst minimising the entrapment of bubbles in the resulting cured sealant on the surface of said hot porous substrate after the composition has cured.