Patent Application
20230022605
This disclosure is concerned with the provision of one-part condensation curable silyl-modified polymer (SMP) based sealant compositions in particular one-part condensation curable SMP based sealant compositions containing a catalyst comprising (i) a titanate and/or zirconate and (ii) a metal carboxylate salt which compositions upon cure provide elastomeric sealants having low modulus and a high elastic recovery.
Room temperature vulcanizable (RTV) SMP based sealant compositions are well known. Generally, such compositions comprise polymers comprising silanol (—Si—OH) containing terminal groups attached to suitable organic polymer backbones or Si-alkoxy containing terminal groups attached to suitable organic polymer backbones and 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 elastomeric sealant product. One or more additional ingredients such as catalysts, reinforcing fillers, non-reinforcing fillers, diluents (e.g. plasticizers 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. Room temperature vulcanizable (RTV) SMP based sealant compositions may be one-part compositions or multiple-part compositions. One-part compositions are generally stored in a substantially anhydrous form to prevent premature cure. The main, if not sole source, of moisture in these compositions are the inorganic fillers, e.g. silica 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.
SMP sealant compositions having at least one Si-alkoxy bond, e.g. Si-methoxy bond in the terminal reactive silyl group and having a polyoxyalkylene polymer as the organic polymeric backbone are widely used for sealants in the construction industry because they have low viscosity and good moisture permeability, adhesion, and weather resistance, and the like. These sealants are often required to provide low-modulus cured products capable of being highly stretched by a small amount of stress for use in a variety of applications not least in the construction industry. The construction industry prefers one-component compositions to negate the need for mixing ingredients before application and compositions with excellent workability.
Low modulus room temperature vulcanisable (RTV) SMP sealant 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 industry. In certain applications, such as the construction of high-rise buildings, it is desirable and often critical to utilize low modulus sealants and/or adhesives for adhering window panes to the frames (metal or otherwise) of a building structure. The low modulus property enables the resulting cured elastomers to easily compress and expand with building movement without causing cohesive or adhesive failure.
Indeed recent architectural trends towards “mirrored” high rise buildings, that is, high rise buildings where the exterior of the building has the appearance of being a large mirror, for both aesthetic and energy-saving reasons, have resulted in there being a great deal of interest in providing suitable low modulus silicone sealants to deliver such effects.
Low modulus sealants typically rely on high molecular weight/chain length polydiorganosiloxane polymers which are end-blocked with reactive groups but have low levels of reactive groups attached along the polymer chain in order to generate cross-linked elastomeric products with low cross-link densities. Such polymers have often been prepared using chain extension processes for which suitable reactive silanes may be utilized as chain extenders during the curing of the composition. However, the use of such high molecular weight polymers typically results in high viscosity compositions especially when reinforcing fillers are also introduced into the composition.
Reinforcing fillers make important contributions to both the cost and rheology of compositions and to properties of resulting elastomeric materials formed from the composition upon cure, e.g. abrasion resistance, tensile and tear strength, hardness and modulus. For example, fine particle fumed silicas are used in compositions from which sealants are made in order to improve strength in the cured elastomer. Inclusion of filler as well as the high molecular weight polymers in a liquid composition leads to stiffening of the composition and a reduction in flowability of the composition, which leads to a need for increased applied shear during mixing to achieve the desired homogenous mixed state of the composition as greater amounts of filler are used. This can be a major problem in room temperature cure materials which are often sought to be gunnable i.e. applied by means of pushing uncured sealant out of a sealant tube using a sealant gun.
The introduction of unreactive liquid plasticizers/extenders (sometimes referred to as process aids) has been utilized as a means of lowering viscosity of uncured compositions. However, once cured the unreactive liquids within the cured sealant may migrate and potentially bleed out of the sealant which, over an extended period of time, can result in the sealant failing and often causing staining and discoloration in/on adjacent substrates.
Low-modulus sealants prepared from compositions containing tetravalent tin based catalysts tend to lose the ability to expand and recover because the use of the tetravalent tin compound as catalyst appears to cause a reduction in the recovery of the cured product so that, the product cannot follow the expansion and shrinkage.
The standard JC/T881 classifies joint sealants which have a low modulus and high elastic recovery in classes 35LM and 50LM. Sealants meeting the technical requirements to be included in these classes are recognized as high-grade sealants, suitable as construction sealants, more particularly as exterior facing sealants. Whilst SMP based sealants which meet the requirements of class 35LM and/or 50 LM according to standard JC/T881 are known, they generally, contain organotin compounds as catalysts and/or phthalate-containing plasticizers both of which can have regulatory issues.
It is well known to people skilled in the art that alkoxy titanium compounds, i.e. alkyl titanates, are suitable catalysts for formulating one component moisture curable silicones (References: Noll, W.; Chemistry and Technology of Silicones, Academic Press Inc., New York, 1968, p. 399, Michael A. Brook, silicon in organic, organometallic and polymer chemistry, John Wiley & sons, Inc. (2000), p. 285). Titanate catalysts have been widely used in skin or diffusion cured one-part condensation curing compositions. Skin or diffusion cure (e.g.
moisture/condensation) commences with the initial formation of a cured skin at the composition/air interface after 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), 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. These compositions are typically available in one-part packages that are applied in a layer that is ≤15 mm thick. Layers thicker than 15 mm are known to result in the presence of uncured material in the depth of the otherwise cured elastomer because moisture is very slow to diffuse into very deep sections.
The disclosure herein seeks to provide a suitable alternative condensation curable SMP based sealant composition, which upon cure provides an elastomeric sealant with a low modulus e.g. ≤0.4 MPa at 100% elongation and a high elastic recovery of ≥80% after 100% extension.
There is provided herein a one-part condensation curable silyl modified polymer
(SMP) based sealant composition comprising:
and
There is also provided herein a method of making the above composition by mixing all the ingredients together.
There is also provided herein an elastomeric sealant material which is the cured product of the composition as hereinbefore described.
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:
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.
Component (a) is a silyl modified organic polymer having at least two (R)m(Y1)3−m—Si groups per molecule where each R is hydroxyl or a hydrolysable group, each Y1 is an alkyl group containing from 1 to 8 carbons and m is 1, 2 or 3.
The (R)m(Y1)3−—Si groups of silyl modified organic polymer (a) may be linked to the organic polymer backbone via any suitable linkage or may be directly bonded where appropriate. Typically, the organic polymer is selected from polyethers, hydrocarbon polymers, acrylate polymers, polyurethanes and polyureas. For example, in the case of silyl modified polyether polymers, (R)m(Y1)3−m—Si groups may be terminal groups linked to the polyether polymer backbone via the following
(R)m(Y1)3−m—Si-D-[NH—C(═O)]k—
Where R, Y1 and m are as hereinbefore described D is a divalent C2-6 alkylene group, alternatively a C2-4 alkylene group, alternatively an ethylene or propylene group and k is 1 or 0. So a silyl modified polyether might be depicted as
(R)m(Y1)3−m—Si-D-[NH—C(═O)]k—O[CH(CH3)—CH2—O]u—[C(═)—NH]k-D-Si(Y1)3−m(R)m
wherein in the above example the polyether repeating group, for the sake of example, is an oxypropylene group [CH(CH3)—CH2−O] with u being the number of repeating units.
Each substituent R in an (R)m(Y1)3−m—Si group may independently be a hydroxyl group or a hydrolysable group. The hydrolysable groups may be selected from acyloxy groups (for example, acetoxy, octanoyloxy, and benzoyloxy groups); ketoximino groups (for example dimethyl ketoximo, and isobutylketoximino); alkoxy groups (for example methoxy, ethoxy and propoxy) and alkenyloxy groups (for example isopropenyloxy and 1-ethyl-2-methylvinyloxy). However, it is preferred that each R is an OH group or an alkoxy group having from 1 to 10 carbons, alternatively an OH group or an alkoxy group having from 1 to 6 carbons, alternatively an OH group, a methoxy group or an ethoxy group, alternatively a methoxy group or an ethoxy group. Substituent Y1 is an alkyl group containing from 1 to 8 carbons, alternatively 1 to 6 carbons, alternatively 1 to 4 carbons. Hence, when R is OH or a hydrolysable group and the hydrolysable group is an alkoxy group, the (R)m(Y1)3−m—Si groups may be selected from —(Y1)SiOH2, —(Y1)2SiOH, —Y1Si(ORb)2, —Si(ORb)3, —(Y1)2SiORb with Rb being an alkyl group having from 1 to 8 carbons.
As previously mentioned, the silyl modified organic polymer (a) has an organic backbone having terminal curable silyl groups. The organic polymeric backbone may be selected from polyethers, hydrocarbon polymers, acrylate polymers, polyurethanes and polyureas.
When the silyl modified organic polymer (a) is an alkoxy silyl terminated organic polymer with the organic polymer being a polyether as previously described. Whereas the polymer backbone is exemplified in the structure above as
(—CpH2p—O—)y
wherein p is an integer from 2 to 4 inclusive and y is an integer ≥4 i.e. of at least four.
An example might be a polyether having the following repeating groups, for example, [CH(CH3)—CH2—O]y
Other polyoxyalkylenes may include for example: units of the structure:
-[—Re—O—(—Rf—O—)h—Pn—CRg2—Pn—O—(—Rf—O—)q1—Re]—
in which Pn is a 1,4-phenylene group, each Re is the same or different and is a divalent hydrocarbon group having 2 to 8 carbon atoms, each Rf is the same or different and is an ethylene group or propylene group, each Rg is the same or different and is a hydrogen atom or methyl group and each of the subscripts h and q1 is a positive integer in the range from 3 to 30.
Alternatively, the organic polymeric backbone may be an acrylate polymer backbone. The acrylate polymer is an addition polymerized polymer of acrylate and/or methacrylate ester monomers, which comprise at least 50%, (i.e. from 50% to 100%) by weight of the monomer units in the acrylate polymer. Examples of acrylate ester monomers are n-butyl, isobutyl, n-propyl, ethyl, methyl, n-hexyl, n-octyl and 2-ethylhexyl acrylates. Examples of methacrylate ester monomers are n-butyl, isobutyl, methyl, n-hexyl, n-octyl, 2-ethylhexyl and lauryl methacrylates. The acrylate polymer preferably has a glass transition temperature (Tg) below ambient temperature; acrylate polymers are generally preferred over methacrylates since they form lower Tg polymers. Polybutyl acrylate is particularly preferred. The acrylate polymer can contain lesser amounts of other monomers such as styrene, acrylonitrile or acrylamide. The acrylate(s) can be polymerized by various methods such as conventional radical polymerization or living radical polymerization such as atom transfer radical polymerization, reversible addition—fragmentation chain transfer polymerization, or anionic polymerization including living anionic polymerization.
Silyl modified organic polymer (a) may also be a silyl modified hydrocarbon polymer. Examples of silyl modified hydrocarbon polymers include silyl modified polyisobutylene. Silyl modified polyisobutylene can for example contain curable silyl groups derived from a silyl-substituted alkyl acrylate or methacrylate monomer such as alkoxydialkylsilylpropyl methacrylate, dialkoxyalkylsilylpropyl methacrylate or trialkoxysilylpropyl methacrylate, which can be reacted with a polyisobutylene.
Typically, the silyl modified organic polymer (a) is present in the composition in an amount of from 10 to 80% by weight of the composition, alternatively from 10 to 60% by weight of the composition, alternatively from 15 to 50% by weight of the composition, alternatively from 15 to 40% by weight of the composition.
The composition also comprises a reinforcing filler (b). Reinforcing filler (b) may contain one or more finely divided, reinforcing fillers such as precipitated calcium carbonate, fumed silica colloidal silica and/or precipitated silica including, for example, rice hull ash. Typically, the surface area of the reinforcing filler (b) is at least 15 m2/g in the case of precipitated calcium carbonate measured in accordance with the BET method (ISO 9277: 2010), alternatively 15 to 50 m2/g, alternatively 15 to 25 m2/g in the case of precipitated calcium carbonate. Silica reinforcing fillers have a typical surface area of at least 50 m2/g in accordance with the BET method (ISO 9277: 2010). In one embodiment reinforcing filler (b) is a precipitated calcium carbonate, precipitated silica and/or fumed silica; alternatively, precipitated calcium carbonate. 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 m2/g measured in accordance with the BET method (ISO 9277: 2010), alternatively of from 100 to 300 m2/g in accordance with the BET method (ISO 9277: 2010).
Reinforcing filler (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. The surface treatment of the fillers makes them easily wetted by the silyl modified organic polymers (a). These surface modified fillers do not clump and can be homogeneously incorporated into the silicone polymer (a) of the base component. 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 silyl modified organic polymer (a).
Typically, the reinforcing fillers are present in the composition in an amount of from 5 to 65% by weight of the composition, alternatively from 20 to 65% by weight of the composition, alternatively from 25 to 60% by weight of the composition, alternatively from 30 to 60% by weight of the composition.
Component (c) of the composition is one or more plasticizers. Plasticizes (c) are often utilized in compositions containing silyl modified organic polymers (a). Given the fact that the backbone of silyl modified organic polymer (a) is substantially organic (i.e. not containing Si—O—Si bonds in the polymer backbone) the plasticizers (c) are generally selected from those which are suitable for plasticizing silyl modified organic polymer (a).
Plasticizer (c) is typically present in an amount of from 5 to 40% by weight of the composition, alternatively from 5 to 35% by weight of the composition, alternatively from 10 to 30% by weight of the composition.
As hereinbefore described the catalyst (d) comprises (i) a titanate and/or zirconate and (ii) a metal carboxylate salt. The titanate and/or zirconate (i) chosen for inclusion in a particular silicone sealant composition depends upon the speed of cure required. Titanate and/or zirconate based catalysts may comprise a compound according to the general formula Ti[OR9]4 or Zr[OR9]4 where each R9 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/zirconate may contain partially unsaturated groups. However, preferred examples of R9 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. Preferably, when each R9 is the same, R9 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 and tetraisopropoxy titanate (as well as zirconate equivalents). Alternatively, the titanate/zirconate may be chelated. The chelation may be with any suitable chelating agent such as an alkyl acetylacetonate such as methyl or ethylacetylacetonate, for example diisopropoxydiethylacetoacetate titanate. Alternatively, the titanate/zirconate may be monoalkoxy titanates bearing three chelating agents such as for example 2-propanolato, tris isooctadecanoato titanate. In one embodiment (i) is a titanate or chelated titanate.
In the present disclosure the catalyst (d) also comprises (ii) a metal carboxylate salt wherein the metal is selected from one or more of zinc, aluminium, bismuth, iron and/or zirconium. The carboxylate groups are of the formula R15COO− where R15 is selected from hydrogen, alkyl groups, alkenyl groups, and aryl groups. Examples of useful alkyl groups for R15 include alkyl groups having from 1 to 18 carbon atoms, alternatively 1 to 8 carbon atoms. Examples of useful alkenyl groups for R15 include alkenyl groups having from 2 to 18 carbon atoms, alternatively 2 to 8 carbon atoms such as vinyl, 2-propenyl, allyl, hexenyl, and octenyl. Examples of useful aryl groups for R15 include aryl groups having from 6 to 18 carbon atoms, alternatively 6 to 8 carbon atoms such as phenyl and benzyl. Alternatively, R15 is methyl, 2-propenyl, allyl, and phenyl. Hence the metal carboxylate salt (ii) in catalyst (e) may be zinc (II) carboxylates, aluminium (III) carboxylates, bismuth (III) carboxylates and/or zirconium (IV) carboxylates, zinc (II) alkylcarboxylates, aluminium (III) alkylcarboxylates, bismuth (III) alkylcarboxylates and/or zirconium (IV) alkylcarboxylates or mixtures thereof. Specific examples of metal carboxylate salt (ii) in catalyst (d) include, zinc ethylhexanoate, bismuth ethylhexanoate , zinc stearate, zinc undecylenate, zinc neodecanoate and iron (III) 2-ethylhexanoate. The titanate and/or zirconate (i) and metal carboxylate salt (ii) of catalyst (d) is provided in a molar ratio of 1:4 to 4:1.
The catalyst (d) is typically present in an amount of from 0.25 to 4.0% by weight of the composition, alternatively from 0.25 to 3% by weight of the composition, alternatively from 0.3% to 2.5% by weight of the composition.
Optionally the catalyst (d) may additionally include a tin catalyst. Any suitable tin based condensation catalyst suitable for participation in the catalysis of the cure. Examples include tin triflates, organic tin metal catalysts such as triethyltin tartrate, tin octoate, tin oleate, tin naphthate, butyltintri-2-ethylhexoate, tin butyrate, carbomethoxyphenyl tin trisuberate, isobutyltintriceroate, and diorganotin salts especially diorganotin dicarboxylate compounds such as dibutyltin dilaurate, dimethyltin dibutyrate, dibutyltin dimethoxide, dibutyltin diacetate, dimethyltin bisneodecanoate, dibutyltin dibenzoate, stannous octoate, dibutyltin bis(2,4-pentanedionate, dimethyltin dineodecanoate (DMTDN) and dibutyltin dioctoate.
When present, tin based catalyst is typically present in an amount of from up to 1.0% by weight of the composition, alternatively from 0.01 to 0.5% by weight of the composition, alternatively from 0.02 to 0.3% by weight of the composition.
The composition as described herein may additionally include one or more additional additives if considered appropriate for the end use. These may include non-reinforcing fillers, rheology modifiers, adhesion promoters, stabilizers such as anti-oxidants, UV and/or light stabilizers and light stabilizers, pigments, water scavengers, (typically the same compounds as those used as cross-linkers or silazanes), and fungicides and/or biocides and the like; It will be appreciated that some of the additives are included in more than one list of additives. Such additives would then have the ability to function in all the different ways referred to.
Suitable non-reinforcing fillers may comprise, for example, crushed quartz, ground calcium carbonate, diatomaceous earths, barium sulphate, iron oxide, titanium dioxide and carbon black, talc, wollastonite may be present in the composition. Other non-reinforcing fillers which might be used alone or in addition to the above include aluminite, calcium sulphate (anhydrite), gypsum, calcium sulphate, magnesium carbonate, clays such as kaolin, aluminum 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.
Aluminum 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 Mg2SiO4. The garnet group comprises ground silicate minerals, such as but not limited to, pyrope; Mg3Al2Si3O12; grossular; and Ca2Al2Si3O12. Aluninosilicates comprise ground silicate minerals, such as but not limited to, sillimanite; Al2SiO5; mullite; 3Al2O3.2SiO2; kyanite; and Al2SiO5
The sheet silicates group comprises silicate minerals, such as but not limited to, mica; K2AI14[Si6Al2O20](OH)4; pyrophyllite; Al4[Si8O20](OH)4; talc; Mg6[Si8O20](OH)4; serpentine for example, asbestos; Kaolinite; Al4[Si4O10](OH)8; and vermiculite.
The non-reinforcing fillers may also be surface treated to be rendered hydrophobic using analogous treating agents as discussed for the reinforcing fillers (b) above.
Rheology modifiers which may be incorporated in moisture curable compositions according to the invention include silicone organic co-polymers such as those described in EP0802233 based on polyols of polyethers or polyesters; waxes such as polyamide waxes, 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.
When present the rheology modifier is present in an amount of up to 10% by weight of the composition, alternatively up to 7.5% by weight of the compositions, alternatively up to 5% of the composition.
Suitable adhesion promoters may comprise alkoxysilanes of the formula
R14dSi(OR15)(4−d)
where subscript d is 1, 2, or 3, alternatively d is 3. Each R14 is independently a monovalent organofunctional group. R14 can be an epoxy functional group such as glycidoxypropyl or (epoxycyclohexyl)ethyl, an amino functional group such as aminoethylaminopropyl or aminopropyl, a methacryloxypropyl, a mercapto functional group such as mercaptopropyl or an unsaturated organic group. Each R15 is independently an unsubstituted, saturated hydrocarbon group of at least 1 carbon atom. R15 may have 1 to 4 carbon atoms, alternatively 1 to 2 carbon atoms. R15 is exemplified by methyl, ethyl, n-propyl, and iso-propyl.
Alternatively the adhesion promoter may be glycidoxypropyltrimethoxysilane or a multifunctional material obtained by reacting two or more of the above. For examples the reaction product of an alkylalkoxysilicone e.g. trimethoxymethylsilane; an aminoalkoxysilane, e.g. 3-aminopropyl trimethoxysilane and an epoxyalkoxysilane e.g. glycidoxypropyl trimethoxysilane; in a weight ratio of (i):(ii):(iii) of 0.1-6:0.1-5:1.
Examples of suitable adhesion promoters may include molecules of the structure
(R′O)3Si(CH2)nN(H)—(CH2)eNH2
in which each R′ may be the same or different and is an alkyl group containing from 1 to 10 carbon atoms, n is from 2 to 10 and e is from 2 to 10;
The adhesion promoter is an optional ingredient which may be present in an amount up to 3% by weight of the composition, alternatively up to 2% of the composition, alternatively in an amount of up to 1% of the composition. Preferably, the speed of hydrolysis of the adhesion promoter should be lower than the speed of hydrolysis of the cross-linker in order to favour diffusion of the molecule towards the substrate rather than its incorporation in the product network.
Any suitable anti-oxidant(s) may be utilized, if deemed required. Examples may include: ethylene bis (oxyethylene) bis(3-tert-butyl-4-hydroxy-5(methylhydrocinnamate) 36443-68-2; tetrakis[methylene(3,5-di-tert-butyl-4-hydroxy hydrocinnamate)]methane 6683-19-8; octadecyl 3,5-di-tert-butyl-4-hydroxyhyrocinnamate 2082-79-3; N,N′-hexamethylene-bis (3,5-di-tert-butyl-4-hydroxyhyrocinnamamide) 23128-74-7; 3,5 -di-tert-butyl-4-hydroxyhydrocinnamic acid, C7-9 branched alkyl esters 125643-61-0; N-phenylbenzene amine, reaction products with 2,4,4-trimethylpentene 68411-46-1; e.g. anti-oxidants sold under the Irganox® name from BASF.
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 TINUVIN® product line from Ciba Specialty Chemicals Inc.
Each type of stabilizer mentioned may be present as and when required in an amount of from 0.1 to 1.0% by weight of the composition.
Pigments are utilized to color the composition as required. Any suitable pigment may be utilized providing it is compatible with the composition. Pigments and/or colored (non-white) non-reinforcing fillers, e.g. carbon black may be utilized to color the composition and ultimately the end elastomeric product e.g. sealant post cure. When present carbon black will function as both a non-reinforcing filler and colorant.
Pigments may be present in the composition in any desired amount providing it does not negatively affect the physical properties of the composition or resulting elastomeric product. Whilst optional they may be present in amounts of up to 20% by weight of the composition, alternatively up to 10% by weight of the composition, alternatively up to 5% by weight of the composition.
Any suitable moisture/water scavenger may be used if required, for example orthoformic acid esters, molecular sieves disilazanes, polysilazanes and/or one or more silanes of the structure
R6jSi(OR5)4−j
Any suitable disilazane or polysilazane moisture/water scavenger may be used, for example silazanes which may be linear or cyclic such as hexamethyldisilazane, hexamethylcyclotrisilazane, octamethyltetrasilazane, trimethyltriphenylcyclotrisilazane, trivinyltrimethylcyclotrisilazane. The moisture/water scavenger may also be one or more and polysilazanes i.e. polymers containing repeating units such as arylensilazanes, such as phenylene silazanes, and alkylenesilazanes such as methylenesilazanes repeating units for example: Hexamethyldisilazane, hexamethylcyclotrisilazane, octamethyltetrasilazane, trimethyltriphenylcyclotrisilazane, and/or trivinyltrimethylcyclotrisilazane.
The moisture/water scavenger is also optional but may be present in the composition in an amount of up to 10% by weight of the composition. When present it is typically present in a range of from 0.1 to 7.5% by weight of the composition, alternatively from 0.2 to 5% by weight of the composition, alternatively from 0.3 to 3% by weight of the composition.
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 0.3% by weight of the composition and may be present in an encapsulated form where required such as described in EP2106418.
The one-part condensation curable silyl modified polymer (SMP) based adhesive composition may comprise any combination of the following ingredients with the proviso that the total % weight is 100 wt. %;
When present a rheology modifier is present in an amount of up to 10% by weight of the composition, alternatively up to 7.5% by weight of the compositions, alternatively up to 5% of the composition;
When present an adhesion promoter is present in an amount up to 3% by weight of the composition, alternatively up to 2% of the composition, alternatively in an amount of up to 1% of the composition.
When present the stabilizer or each different type of stabiliser present may be present in an amount of from 0.1 to 1.0% by weight of the composition; and the composition may comprise other additives as defined herein.
The compositions are preferably room temperature vulcanisable compositions in that they cure at room temperature without heating but may if deemed appropriate be accelerated by heating. Typically, the composition may be cured for any suitable period, for example the composition will cure about 2 to 3mm in depth after 24 hours curing at room temperature (approximately 23° C.) and 50% relative humidity (RH).
Having both a low modulus and higher elastic recovery can endow the sealant with higher movement capability. While in general, low modulus sealants normally exhibit low elastic recovery the elastomeric product made from the composition herein has been developed to provide a modulus of less than 0.4 MPa at 100% elongation (ASTM D412-98a(2002)e1) and elastic recovery above than 80% after 100% extension using the test method described herein. Hence, the present composition and the resulting elastomeric material after cure, satisfies the requirements for the sealant to be in classes 35LM and 50LM based on the requirements set in standard JC/T881 by having a having a Balanced modulus and elastic recovery: a sealant formulation after cure has modulus less than 0.4 MPa at 100% elongation and elastic recovery above than 80% after 100% extension as well as good adhesion on concrete.
The ingredients and their amounts are designed to provide a low modulus and high extension sealant, adhesive and/or coating composition. Low modulus silicone sealant compositions are preferably “gunnable” i.e. they have a suitable extrusion capability i.e. a minimum extrusion rate of 10 ml/min as measured by ASTM C1183-04, alternatively 10 to 1000 mL/min, and alternatively 100 to 1000 mL/min.
The ingredients and their amounts in the sealant composition are selected to impart a movement capability to the post-cured sealant material. The movement capability is greater than 25%, alternatively movement capability ranges from 25% to 50%, as measured by ASTM C719-13.
A sealant composition as hereinbefore described may be a gunnable sealant composition used for
A sealant composition as hereinbefore described may be applied on to any suitable substrate. Suitable substrates may include, but are not limited to, glass; concrete; brick; stucco;
metals, such as aluminium, copper, gold, nickel, silicon, silver, stainless steel alloys, and titanium; ceramic materials; plastics including engineered plastics such as epoxies, polycarbonates, poly(butylene terephthalate) resins, polyamide resins and blends thereof, such as blends of polyamide resins with syndiotactic polystyrene such as those commercially available from The Dow Chemical Company, of Midland, Mich., U.S.A., acrylonitrile-butadiene-styrenes, styrene-modified poly(phenylene oxides), poly(phenylene sulfides), vinyl esters, polyphthalamides, and polyimides; cellulosic substrates such as paper, fabric, and wood; and combinations thereof. When more than one substrate is used, there is no requirement for the substrates to be made of the same material. For example, it is possible to form a laminate of plastic and metal substrates or wood and plastic substrates.
In the case of silicone sealant compositions as hereinbefore described, there is also provided a method for filling a space between two substrates so as to create a seal therebetween, comprising:
In one alternative, a sealant composition as hereinbefore described may be a self-levelling highway sealant. A self-levelling sealant composition means it is “self-levelling” when extruded from a storage container into a horizontal joint; that is, the sealant will flow under the force of gravity sufficiently to provide intimate contact between the sealant and the sides of the joint space. This allows maximum adhesion of the sealant to the joint surface to take place. The self-levelling also does away with the necessity of tooling the sealant after it is placed into the joint, such as is required with a sealant which is designed for use in both horizontal and vertical joints. Hence, the sealant flow sufficiently well to fill a crack upon application. If the sealant has sufficient flow, under the force of gravity, it will form an intimate contact with the sides of the irregular crack walls and form a good bond; without the necessity of tooling the sealant after it is extruded into the crack, in order to mechanically force it into contact with the crack sidewalls.
Self-levelling compositions as described herein are useful as a sealant having the unique combination of properties required to function in the sealing of asphalt pavement. Asphalt paving material is used to form asphalt highways by building up an appreciable thickness of material, such as 20.32 cm, and for rehabilitating deteriorating concrete highways by overlaying with a layer of a thickness of about 10.16 cm. Asphalt overlays undergo a phenomenon known as reflection cracking in which cracks form in the asphalt overlay due to the movement of the underlying concrete at the joints present in the concrete. These reflection cracks need to be sealed to prevent the intrusion of water into the crack, which will cause further destruction of the asphalt pavement when the water freezes and expands.
In order to form an effective seal for cracks that are subjected to movement for any reason, such as thermal expansion and contraction, the seal material must bond to the interface at the sidewall of the crack and must not fail cohesively when the crack compresses and expands. In the case of the asphalt pavement, the sealant must not exert enough strain on the asphalt at the interface to cause the asphalt itself to fail; that is, the 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.
In such instances, the modulus of the cured material is designed to be low enough so that it does not exert sufficient force on the asphalt to cause the asphalt to fail cohesively. The cured material is such that when it is put under tension, the level of stress caused by the tension decreases with time so that the joint is not subjected to high stress levels, even if the elongation is severe.
Alternatively, the silicone elastomeric composition provided herein may be utilized as an elastomeric coating composition, e.g. as a barrier coating for construction materials or as a weatherproof coating for a roof, the composition may have a viscosity not dissimilar to a paint thereby enabling application by e.g. brush, roller or spray gun or the like. A coating composition as described herein, when applied onto a substrate, may be designed to provide the substrate with e.g. long-term protection from air and water infiltration, under normal movement situations caused by e.g. seasonal thermal expansion and/or contraction, ultra-violet light and the weather. Such a coating composition can maintain water protection properties even when exposed to sunlight, rain snow or temperature extremes.
Comparative sealant compositions were prepared using the compositions in Table 1 which can be seen to contain the essential ingredients and several optional ingredients.
Kaneka Silyl™ SAX510 and Kaneka Silyl™ SAX520 are both isocyanate free polymers having a polymeric chain of repeating polypropyleneoxide units and with trimethoxysilyl terminal groups;
The comparative sealant compositions were prepared using the above compositions on a 10 L Turello Mixer according to the process described as below.
The mixture was then stirred at 800 revolutions per minute (rpm) at full vacuum for 90 minutes at 105° C. and cooled to <45° C. Once the temperature of the composition was <45° C., the remaining ingredients were added i.e. vinyltrimethoxy silane, the relevant catalyst(s), ethylenediaminepropyltrimethoxysilane and methyl acetoacetate. The final mixture was then mixed for a further 20 minutes in a nitrogen atmosphere and subsequently deaired by applying a vacuum at −75 kPa pressure and then was then packaged into standard cartridges for testing.
The compositions prepared as described above were then tested for their physical properties as depicted in Table 2 below. All samples tested hereafter in accordance with (ASTM D412-98a (2002)e1) utilized dumbbell shaped test pieces.
Elastic recovery: The length of 2.54 cm (1.0 inch) was marked by ink on the dumbbell specimens with about 2 mm in thickness as original length (A); The dumbbell was stretched by 100%, (i.e. to 5.08 cm, 2.0 inch=B) and maintained at 100% extension for 24 hours; subsequently the dumbbell was released and allowed to recover for 1 hour; Test final length (C) between the marks. The elastic recovery was determined as =(B-C)/(B-A)*100%
Adhesion properties of the Comparative examples were also assessed and are depicted in Table 2b below.
Primer P is DOWSIL™ Construction Primer P a commercially available Adhesion promoter from Dow Silicones Corporation for use on masonry surfaces. It comprises an alkoxy silane resin formulation in solvent.
Cohesive failure (CF) is observed when the coating itself breaks without detaching from the substrate (for example, steel plate). 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).
The Examples in accordance with this disclosure were also made via the same method as described above using the compositions depicted in Table 3 below
For comparative example 1, the sample with only Zn(EHA)2 as catalyst cannot fully cure even after seven days conditioning at room temperature and proved low catalytic activity. As for comparative example 2 and 3 only with Ti catalyst, the samples can get low modulus and high elastic recovery, but the adhesion was not good on concrete, especially after water immersion condition. As for inventive examples 4, and 5 using the catalyst described herein, both samples recorded modulus values of less than 0.4 MPa with elastic recovery above than 80% and had good adhesion on concrete. The addition of Zn(EHA)2 and Ti separately as catalyst got similar results as the pre-mixing of Zn(EHA)2 and Ti, such as the low modulus, high elastic recovery and good adhesion on concrete, as seen from inventive example 6 and 7.
The standard JC/T881 classifies joint sealants which have a low modulus and high elastic recovery in classes 35LM and 50LM. Sealants meeting the technical requirements to be included in these classes are recognized as high-grade sealants, suitable as construction sealants, more particularly as exterior facing sealants. Whilst SMP based sealants which meet the requirements of class 35LM and/or 50 LM according to standard JC/T881 are known, they generally, contain organotin compounds as catalysts and/or phthalate-containing plasticizers both of which can have regulatory issues whereas we have shown that catalysts as described herein provide suitable elastomeric sealants.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2019/125815 | 12/17/2019 | WO |
