Process for producing storage-stable activators for glass and ceramic substrates

Abstract

The present invention relates to a process for preparing an adhesion promoting pretreatment composition, comprising the steps of: a) providing a reaction vessel containing 100 parts by weight of an alcohol having 1 to 4 carbon atoms; b) adding at least one organosilane OS in an amount such that between 0.15 and 0.8 parts by weight of silicon is added, optionally adding at least one organothionate OT in an amount such that between 0.01 and 0.8 parts by weight of titanium is added, and optionally adding at least one organozirconate OZ in an amount such that between 0.01 and 0.8 parts by weight of zirconium is added; c) adding acid A in an amount such that the resulting pH is between 3.5 and 7; d) adding water, wherein the amount of water added is at least equimolar or in excess of the molar amount of hydrolyzable silicon-, titanium-, and / or zirconium-bonded groups present in the total added organosilanes OS, organothionates OT, and organozirconates OZ, and wherein the amount of water is at most 25 parts by weight; e) optionally adding further additives selected from colorants, UV markers, condensation catalysts, or stabilizers; f) waiting, optionally with stirring, shaking and / or heating, until all hydrolyzable groups present in all added organosilanes OS, organozirconates OT and organozirconates OZ have been hydrolyzed. This process results in a highly storage stable adhesion-promoting pretreatment composition that is useful in automotive glass replacement operations, regardless of ambient weather conditions, and allows for permanent adhesive bonds with improved water stability.

Description

[Technical Field]

[0001] The present invention relates to processes for preparing adhesion-promoting pretreatment compositions suitable as adhesion-promoting activators, particularly for glass and ceramic substrates, as well as to the compositions themselves and their uses. [Background technology]

[0002] Adhesively bonding substrates using adhesives such as polyurethanes is a widely used technique in the construction and manufacturing industries. However, some substrates (bonding substrates) present problems in this regard because certain adhesives are unable to establish sufficient initial adhesion or lose adhesion over time, especially under harsh environmental conditions (e.g., heat or moisture). For this reason, adhesion promoter compositions (also called activators) have long been used to improve adhesion or to maintain adequate adhesion throughout the life of the adhesively bonded article, either by applying them to such problematic substrates prior to bonding to form an interlayer between the substrate and the adhesive, or by reacting the adhesive thereon to form covalently bonded chemical residues. A particularly important field of use for adhesion promoter compositions is automotive glass repair (AGR), because these applications involve difficult to bond substrates such as glass and ceramics, which often do not bond easily with adhesives commonly used in these applications, especially polyurethane-based adhesives, which are most commonly used in this field. Furthermore, especially in AGR applications, the bonding process is often carried out under adverse conditions (e.g., low temperature or humid climates), while there is always a demand for the adhesive bond to form quickly and be as durable as possible.

[0003] Typically, such adhesion-promoting compositions are organic or aqueous solutions containing dispersed or dissolved organosilanes, which provide at least covalently bonded reactive groups for bonding ideal interlayers, i.e., glass and ceramics, with curable adhesives (by coating the latter on the substrate surface and crosslinking). More specifically, such adhesion promoter compositions are used as primers and activators, i.e., as adhesion-promoting undercoats or adhesion-promoting cleaning compositions. Such compositions often contain inert, readily volatile solvents to ensure rapid flash-off (solvent evaporation). However, the inclusion of organic solvents presents environmental and occupational safety challenges. Furthermore, the use of solvent-based silane-containing pretreatment compositions generally requires the addition of significant amounts of silane hydrolysis and condensation catalysts to ensure sufficiently rapid reaction of these silanes on the substrate. However, this severely impairs the storage and handling stability of such compositions, since even traces of moisture in the container containing the composition can easily cause undesirable precipitation and gelling reactions.

[0004] Aqueous adhesion promoter compositions based on organosilanes and containing water as a solvent are known as EHS-friendly alternatives to solvent-based compositions. Furthermore, they are significantly less susceptible to hydrolysis due to contact with additional water and are easier to handle. However, they have several significant drawbacks. Silane-based aqueous adhesion promoter compositions suffer from either relatively poor shelf life (shelf life) when sufficiently reactive, or insufficient reactivity (shelf life) when sufficiently stable. This is because the silanes used contain hydrolyzable functional groups that, when mixed with water, hydrolyze to form silanol groups (Si—OH). These silanol groups are often reactive and spontaneously condense with each other to form relatively high molecular weight condensation products, which form insoluble precipitates in the adhesion promoter composition and impair its functionality.

[0005] Additionally, the use of aminosilanes and / or mercaptosilanes in such aqueous adhesion promoter compositions is also known. Emulsifying mercaptosilanes or oligosilane-mercaptosilane mixtures in water is particularly difficult because the mercaptosilanes are water-insoluble until the silane groups are hydrolyzed. To bring the silanes into the water before hydrolysis, a completely uniform distribution must be maintained. Additionally, the pH must be adjusted with an acid, such as acetic acid, to delay further condensation as much as possible. Therefore, the silanes and water must be mixed quickly and uniformly, which requires special mixing equipment.

[0006] Because of this effect, aqueous adhesion promoter compositions are generally sold as two-component systems (e.g., Sika HydroPrep®-100, manufactured by Sika Schweiz AG), and a mixing process is required on-site before use to combine the two components. It is important to mix the two components very quickly and homogeneously with very pronounced turbulence. Specially developed equipment ("shakers") is required for this purpose. After blending, the prepared product has a storage stability ("pot life") of no more than 30 days.

[0007] Another aqueous primer composition is disclosed in WO 2013 / 116004. This composition combines both an organosilane and an organotitanate, further improving its adhesion-promoting performance on certain substrates compared to compositions based on silane alone. However, combining an organosilane and an organotitanate in a one-component aqueous composition poses particularly stringent requirements for the solution's storage stability, because irreversible precipitation and agglomeration of the silane and titanate or their reaction products is easily observed. Following the teachings of WO 2013 / 116004, a stable solution with continued clarity and no precipitation can be obtained by using a significant amount of stabilizing surfactant. However, using such a large amount of surfactant often leads to other problems, such as migration of these substances onto or into the surface of the substrate, interference with the bonding process or the bond itself, or subsequent loss of adhesion due to chemical reactions within the adhesive or with the substrate, as with the emulsifiers mentioned above.

[0008] A further major drawback of water-based pretreatment compositions is their limitation with respect to application temperature: at temperatures of 0° C. or below, evaporation of water is severely limited and even water-based pretreatment compositions freeze and solidify, rendering them unusable.

[0009] Solvent-based activators based on silanes and, in some cases, titanates and / or zirconates are also disclosed, for example, in WO 2008 / 061981. The adhesion-promoting compositions disclosed therein are particularly suitable for low-temperature applications below 0°C, even at subzero temperatures. However, the hydrolysis and crosslinking reactions of the active silanes and other components contained therein require water, which usually proceeds very slowly because the water is supplied from atmospheric moisture or water adsorbed on the surface of the substrate. To accelerate this reaction, large amounts of catalysts for these reactions are generally added, but this results in significant sensitivity to moisture and significantly reduces the storage stability of the composition, especially once the container is opened. Furthermore, most solvents used in solvent-based activators are VOCs and / or have EHS issues.

[0010] Furthermore, solvent-based activators often exhibit a loss of adhesion when the adhesive bond is severely exposed to water.

[0011] WO 2006 / 049368 A1 discloses a coating composition for improving the stain resistance and weather resistance of a substrate, which is based on a blend of various organosilanes and metal oxides, isopropanol and acetic acid, a silicone-acrylic based polymer, water, and organic solvents, including various alcohols. Summary of the Invention [Problem to be solved by the invention]

[0012] It would therefore be desirable to have an adhesion-promoting pretreatment composition that can be manufactured as a consumer-friendly, single-component composition using a simple process using readily available raw materials and that does not require protection from moisture during manufacture. It would also be desirable for such a composition to be usable without restriction in hot or cold climate conditions. It would also be desirable for such a composition to have complete shelf-life stability for months to years, to exhibit no precipitation or discoloration even upon repeated exposure of its container to the atmosphere, and to exhibit excellent adhesion-promoting performance and a favorable EHS profile, particularly in AGR applications. Additionally, adhesive bonds formed using such compositions should have excellent resistance to water penetration. [Means for solving the problem]

[0013] It is therefore an object of the present invention to provide a simple process for preparing storage-stable, silane-based and optionally titanate-based adhesion-promoting pretreatment compositions that are moisture-insensitive, obtainable as ready-to-use one-component compositions, EHS-friendly, compatible with slow-cure or fast-cure polyurethane adhesives, and capable of being applied in a variety of weather conditions, including high temperature, high humidity, and low temperature (well below 0°C), capable of forming adhesive bonds that are water-insensitive, and yet exhibit excellent, long-lasting adhesion-promoting performance even after long-term storage and exposure to the atmosphere.

[0014] Surprisingly, it has now been found possible to achieve this object by a stepwise approach as defined in claim 1, in which the required components are added to an alcohol having 1 to 4 carbon atoms, preferably ethanol, as the sole solvent; and the active components are prehydrolyzed; thereby producing an extremely storage-stable, one-component adhesion-promoting pretreatment composition that exhibits no precipitation or other degradation even after repeated exposure to air and moisture, and that maintains both its stability and its adhesion-promoting performance even after prolonged storage of several months or more. The simple, low-cost process of the present invention does not require specialized equipment and can be successfully carried out using inexpensive, widely available raw materials.

[0015] The adhesion promoting compositions obtained using the process of the present invention are highly effective adhesion promoting pretreatment compositions for adhesive bonding operations, especially when adhesives based on polyurethane polymers or polymers with reactive silane groups are used, especially on substrates such as glass or ceramics.

[0016] Surprisingly, the adhesion promoting compositions produced by the process of the present invention are comparable to or superior to current art water-based or solvent-based adhesion promoters in terms of adhesion promoting performance and water resistance, and do not lose their adhesion promoting performance even after extended storage, or even after exposure to moisture or atmosphere.

[0017] Accordingly, the present invention relates to a process for preparing an adhesion-promoting pretreatment composition, comprising the steps of: a) providing a reaction vessel containing 100 parts by weight of an alcohol having 1 to 4 carbon atoms, in particular ethanol; b) adding at least one organosilane OS in an amount such that between 0.15 and 0.8 parts by weight of silicon is added, and optionally adding at least one organotitanate OT in an amount such that between 0.01 and 0.8 parts by weight of titanium is added, and optionally adding at least one organozirconate OZ in an amount such that between 0.01 and 0.8 parts by weight of zirconium is added; c) adding an acid A, in particular acetic acid, in such an amount that the resulting pH is between 3.5 and 7; d) adding water, wherein the amount of water added is at least equimolar or in excess of the molar amount of hydrolyzable silicon-, titanium-, and / or zirconium-bonded groups present in the total added organosilanes OS, organothionates OT, and organozirconates OZ, and wherein the amount of water is at most 25 parts by weight; e) optionally adding further additives selected from colorants, UV markers, condensation catalysts or stabilizers; f) waiting, optionally with stirring, shaking and / or heating, until all hydrolyzable groups present in all added organosilanes OS, organozirconates OT and organozirconates OZ have been hydrolyzed.

[0018] Surprisingly, we have found that the simple process of the present invention can be used to produce long-term, storage-stable, tough solutions of prehydrolyzed organosilanes, organotitanates, and / or organozirconates in ethanol-based compositions, which are highly suitable as adhesion promoters, or activators, particularly for adhesive bonding operations involving glass or ceramic substrates. The compositions obtained by the process of the present invention encompass all the advantages of water-based and solvent-based silane-, titanate-, or zirconate-based pretreatment compositions, yet lack the inherent disadvantages commonly associated with water-based or solvent-based pretreatment compositions. Another surprising finding is that the adhesion-promoting effects of the present compositions do not deteriorate or disappear even after prolonged storage or exposure to humid atmospheres. Nevertheless, the compositions of the present invention exhibit excellent adhesion-promoting performance and are compatible with fast- or accelerated-cure adhesives, regardless of the climatic conditions at the time of application.

[0019] The adhesion-promoting pretreatment compositions of the present invention are very generally suitable as reactive cleaning and bonding pretreatments for substrates, in particular glass and glass ceramics, in particular for automotive glass repair or as pretreatments for adhesive bonding, in particular with polyurethane adhesives or adhesives based on silane-functional polymers, including RTV silicones and organosilane-functional polymers, preferably one-component polyurethane or silane-curing adhesives, for direct glazing in automotive assembly. DETAILED DESCRIPTION OF THE INVENTION

[0020] As used herein, the terms "silane" and "organosilane" refer to compounds having, first, at least one hydrolyzable group, typically two or three hydrolyzable groups, preferably an alkoxy or acyloxy group, directly bonded to the silicon atom via an Si-O bond, and, second, at least one organic group, particularly an Si-C bond, bonded to the silicon atom. Such silanes having an alkoxy or acyloxy group are also known to those skilled in the art as organoalkoxysilanes or organoacyloxysilanes.

[0021] These silanes have the property of undergoing hydrolysis upon contact with moisture, thereby producing organosilanols, i.e., organosilicon compounds containing one or more silanol groups (Si-OH groups), which then undergo condensation reactions to give organosiloxanes, i.e., organosilicon compounds containing one or more siloxane groups (Si-O-Si groups).

[0022] "Epoxysilane," "aminosilane," and "mercaptosilane" refer to organosilanes whose organic groups contain epoxy, amino, and mercapto groups, respectively. Organosilicon compounds containing amino, mercapto, or oxirane groups are also referred to as "aminosilanes," "mercaptosilanes," or "epoxysilanes."

[0023] "Primary aminosilane" refers to an aminosilane having a primary amino group, i.e., an NH group bonded to an organic group. "Secondary aminosilane" refers to an aminosilane having a secondary amino group, i.e., an NH group bonded to two organic groups.

[0024] The Si-bonded hydrolyzable groups are groups that can be hydrolyzed to silanol groups, optionally in the presence of a catalyst. The hydrolysis reaction product is a silane in which the hydrolyzable groups are at least partially hydrolyzed, i.e., at least some of the hydrolyzable groups are replaced by OH groups. The condensation reaction product includes the condensation of two or more hydrolyzed silanes of this type. The products of silane hydrolysis and condensation reactions are known to those skilled in the art.

[0025] The expression "independently" is always used herein to mean "independently within the same molecule", unless there is another alternative.

[0026] A substance or composition is "storage-stable" or "storable" if it can be stored at room temperature in a suitable container for an extended period of time, typically at least three months and up to six months or more, without any change in its application or use properties to a degree of relevance for the use thereof as a result of such storage.

[0027] "Mass" and "weight" are used synonymously herein. Thus, "weight percent" (wt%) is the percent mass fraction stated relative to the mass (weight) of the total composition, or, depending on the context, the entire molecule, unless otherwise specified.

[0028] "Room temperature" refers to a temperature of 23±2°C, especially 23°C.

[0029] All industry and official standards mentioned herein relate to the editions in effect as of the original filing date unless otherwise specified.

[0030] In a first aspect, the present invention relates to a process for preparing an adhesion-promoting pretreatment composition, which comprises the steps of: a) providing a reaction vessel containing 100 parts by weight of an alcohol having 1 to 4 carbon atoms, in particular ethanol; b) adding at least one organosilane OS in an amount such that between 0.15 and 0.8 parts by weight of silicon is added, and optionally adding at least one organotitanate OT in an amount such that between 0.01 and 0.8 parts by weight of titanium is added, and optionally adding at least one organozirconate OZ in an amount such that between 0.01 and 0.8 parts by weight of zirconium is added; c) adding an acid A, in particular acetic acid, in such an amount that the resulting pH is between 3.5 and 7; d) adding water, wherein the amount of water added is at least equimolar or in excess of the molar amount of hydrolyzable silicon-, titanium-, and / or zirconium-bonded groups present in the total added organosilanes OS, organothionates OT, and organozirconates OZ, and wherein the amount of water is at most 25 parts by weight; e) optionally adding further additives selected from colorants, UV markers, condensation catalysts or stabilizers; f) waiting, optionally with stirring, shaking and / or heating, until all hydrolyzable groups present in all added organosilanes OS, organozirconates OT and organozirconates OZ have been hydrolyzed.

[0031] The above steps are preferably carried out consecutively in the order a) to f), and between each two steps it may be advantageous to include further steps, such as storing or transporting the intermediate composition, or process steps such as heating, mixing or cooling, or addition of additional components.

[0032] The first step a) involves providing a reaction vessel with 100 parts by weight of an alcohol having 1 to 4 carbon atoms, these parts by weight being relative to other components that will be added in subsequent process steps, such as step b) or step c).

[0033] The solvent used in step a) should be an alcohol having 1 to 4 carbon atoms. Specific examples of suitable alcohols include methanol, ethanol, n-propanol (1-propanol), isopropanol (propan-2-ol), n-butanol (1-butanol), isobutanol (2-methyl-1-propanol), sec-butanol (2-butanol), and tert-butanol (2-methyl-2-propanol). Among these, methanol, ethanol, isopropanol, and tert-butanol are preferred because they have the advantage of having a lower boiling point than the others.

[0034] Ethanol has been found to be the most preferred solvent for the process of the present invention because it is capable of adequately dissolving all of the components, is compatible with water, evaporates fairly quickly, and does not pose significant EHS hazards. In addition, ethanol is particularly compatible with the materials added in step b) and allows for exceptional storage stability of the composition.

[0035] Furthermore, ethanol has good cleaning and degreasing properties, which is an added advantage when the compositions prepared using the process of the present invention are used as activators, since it not only deposits the active adhesion-promoting compound onto the substrate surface, but also removes unwanted deposits such as dirt, grease, and oil from the substrate.

[0036] The alcohol having 1 to 4 carbon atoms, preferably ethanol, is preferably the only organic solvent used in the process of the present invention and subsequently in the compositions produced thereby, although small amounts of co-solvents can be added, for example, to improve substrate cleanability or to improve the solubility of certain components.

[0037] Co-solvents are understood to mean organic solvents miscible with ethanol, such as other alcohols (including diols, ethers, or ketones). However, it is preferred to use such organic solvents in only small amounts, typically less than 10% by weight, based on the total solvent content, including ethanol, in the composition. It is more preferred that the composition be completely free of such organic co-solvents, apart from trace amounts of alcohol formed by hydrolysis of the alkoxysilanes used in the aqueous composition. Since the use of co-solvents results in greater VOC issues, it is preferred that the presence of such co-solvents, if any, be non-relevant in terms of EHS.

[0038] However, it is possible, and may be advantageous, to add an excess of water in step d) so that unreacted water remains in the composition as a co-solvent. The maximum amount of water added in step d) is 25 parts by weight per 100 parts by weight of alcohol in step a). It is preferred that the amount of water added does not exceed 20 parts by weight.

[0039] The total amount of water in the composition after step f) is preferably at most 20% by weight, more preferably at most 15% by weight, based on the total composition.

[0040] Step b) of the process of the present invention comprises adding at least one organosilane OS in an amount that results in the addition of between 0.15 and 0.8 parts by weight of silicon, and optionally adding at least one organotitanate OT in an amount that results in the addition of between 0.01 and 0.8 parts by weight of titanium, and optionally adding at least one organozirconate OZ in an amount that results in the addition of between 0.01 and 0.8 parts by weight of zirconium.

[0041] These amounts are calculated based on the added weight of silicon, optionally titanium, and optionally zirconium atoms contained in the added organosilane OS, the optionally added organotitanate OT, and the optionally added organozirconate OZ. This calculation allows for differences between individual organosilanes, for example, because they differ from one another in terms of their individual functionalities. For example, an organosilane OS of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane contains 12.63 wt. % silicon, while another organosilane OS of bis(trimethoxysilylpropyl)amine contains 16.45 wt. % silicon (based on each molecule). The amount of silicon in these two examples provides a much more accurate indication of the effective amount of active bonding component than the total weight, because the latter can vary significantly between different organosilanes.

[0042] In a preferred embodiment, step b) includes adding between 1 and 5 parts by weight of at least one organosilane OS, optionally between 0.1 and 5 parts by weight of at least one organotitanate OT, and optionally between 0.1 and 5 parts by weight of at least one organozirconate OZ to the ethanol present in step a), where these amounts are based on the total weight of the molecules added and not on the individual Si, Ti, or Zr atoms, but still encompass the most preferred embodiments of the organosilane OS, organotitanate OT, and organozirconate OZ.

[0043] It is essential in step b) that at least one organosilane OS is added in an amount of between 0.15 and 0.8 parts by weight of silicon to 100 parts by weight of the alcohol having 1 to 4 carbon atoms, preferably ethanol. It has been found that higher amounts adversely affect the storage stability of the composition, while not further improving the adhesion promoting performance.

[0044] The organosilanes OS added to the composition in step b) each have at least one Si-bonded hydrolyzable group, which may be partially hydrolyzed initially, but is preferably unhydrolyzed. This may be any conventional hydrolyzable group, with alkoxy and acyloxy groups being preferred, and C1-C4 alkoxy groups being particularly preferred. After mixing with water in step d), the hydrolyzable groups can be hydrolyzed over time. The result is a hydrolysis reaction product in which at least some, and later all, of the hydrolyzable groups are replaced by OH groups (silanol groups). Further reaction may involve the formation of a certain proportion of condensation reaction products via the silanol groups formed in the hydrolysis reaction product. For example, the organosilanes present may be in a fully hydrolyzed, partially hydrolyzed, or even partially condensed form. However, the acid A added in step c) will prevent extensive condensation reactions.

[0045] Particularly suitable organosilanes OS are organosilicon compounds of formula (I) or (II) or (III). [ka] R 1 is defined herein as a linear or branched, optionally cyclic, alkylene group having 1 to 20 carbon atoms, optionally containing an aromatic residue, and optionally containing one or more heteroatoms, particularly nitrogen atoms. R 2 is herein H or an alkyl group having 1 to 5 carbon atoms, in particular methyl or ethyl, or an acyl group, in particular acetyl. R 3 As used herein, is an alkyl group having 1 to 8 carbon atoms, particularly methyl. X, as used herein, is H or a functional group selected from the group comprising OH, (meth)acryloyloxy, mercapto, glycidoxy, epoxy, primary amine, primary and secondary amino groups, alkylamine including secondary alkyl or arylamine, acylthio, and vinyl, preferably amine in all of the above forms. For completeness, acylthio in this specification should be understood to mean the following substituent: [ka] where R 4 is in particular alkyl having 1 to 20 carbon atoms, and the dotted line indicates the substituent R 1 represents the bond to X 1 As used herein, is a functional group selected from the group including NH, S, S2, and S4. X 2 is herein a functional group selected from groups including N and isocyanurate. The index a here represents one of the values ​​0, 1 and 2, preferably 0. Substituent R 1 is in particular a methylene, propylene, methylpropylene, butylene or dimethylbutylene radical. 1 Particularly preferred is a propylene group.

[0046] Suitable examples of organosilicon compounds of formula (I) are organosilicon compounds selected from the group comprising: Octyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, methyloctyldimethoxysilane; 3-methacryloyloxypropyltrialkoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane; 3-Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldimethoxymethylsilane, 3-amino-2-methylpropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyldimethoxymethylsilane, 4-aminobutyltrimethoxysilane, 4-aminobutyldimethoxymethylsilane, 4-amino-3-methylbutyltrimethoxysilane, 4-amino-3,3-dimethylbutyltrimethoxysilane Xysilane, 4-amino-3,3-dimethylbutyldimethoxymethylsilane, [3-(2-aminoethylamino)propyl]trimethoxysilane (=4,7,10-triazadecyltrimethoxysilane), 2-aminoethyltrimethoxysilane, 2-aminoethyldimethoxymethylsilane, aminomethyltrimethoxysilane, aminomethyldimethoxymethylsilane, aminomethylmethoxydimethylsilane, 7-amino-4-oxaheptyldimethoxymethylsilane, N-(methyl)-3-aminopropyltrimethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane; 3-Acylthiopropyltrimethoxysilane; Vinyltrimethoxysilane, and vinyltriethoxysilane.

[0047] Also preferred are the aforementioned organosilicon compounds in which the alkoxy groups are replaced with acetoxy groups, such as octyltriacetoxysilane (octyl-Si(O(O=C)CH)). Such organosilicon compounds release acetic acid upon hydrolysis.

[0048] Among those organosilicon compounds described above, preferred are those having organic substituents attached to the silicon atom and further having functional groups, i.e., not alkyl groups, and conforming to formula (I) in which X is not H.

[0049] Suitable examples of organosilicon compounds of formula (II) are organosilicon compounds selected from the group comprising: bis[3-(trimethoxysilyl)propyl]amine, bis[3-(triethoxysilyl)propyl]amine, 4,4,15,15-tetraethoxy-3,16-dioxa-8,9,10,11-tetrathia-4-15-disilaoctadecane (bis(triethoxysilylpropyl)polysulfide, or bis(triethoxysilylpropyl)tetrasulfane), bis(triethoxysilylpropyl)disulfide.

[0050] Suitable examples of organosilicon compounds of formula (III) are organosilicon compounds selected from the group comprising: tris[3-(trimethoxysilyl)propyl]amine, tris[3-(triethoxysilyl)propyl]amine, 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione urea (=tris(3-(trimethoxysilyl)propyl)isocyanurate), and 1,3,5-tris[3-(triethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione urea (=tris(3-(triethoxysilyl)propyl)isocyanurate).

[0051] Optionally, the composition may include at least one tetraalkoxysilane of formula (IV). Si(OR 4 )4(IV) [In the formula, R 4 are independently an alkyl group having 1 to 4 carbon atoms or an acyl group, particularly an acetyl group. Such tetraalkoxysilanes include, for example, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrapropoxysilane, tetrabutoxysilane, and tetraacetoxysilane. Tetraethoxysilane is particularly preferred. As with aminosilanes and mercaptosilanes, tetraalkoxysilanes can be hydrolyzed in the presence of water and, in some cases, condensed with other silanes.

[0052] The organosilane OS preferably includes at least one organosilane or condensate thereof having at least one Si-bonded hydrolyzable group and at least one primary and / or secondary amino group. If two or more types of organosilane OS are added, they may be added sequentially without any particular order. However, it is often possible to add all the silanes simultaneously in the form of a silane premix. These additional organosilanes OS are, in particular, organosilanes or oligomers of such organosilanes, which have at least one Si-bonded hydrolyzable group and at least one additional functional group selected from alkyl, alkylene, epoxy, mercapto, hydroxyl, and isocyanurate groups (including mercaptosilanes and epoxysilanes, as described below).

[0053] Preferred organosilanes OS are aminosilanes, in particular those in which X=NH or NH—CH—CH—NH, X 1 =NH and X 2 ═N. Particularly preferred are 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, bis[3-(trimethoxysilyl)propyl]amine, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and bis[3-(triethoxysilyl)propyl]amine, and mixtures thereof with one another.

[0054] Suitable aminosilanes as organosilane OS are in particular aminosilanes selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyldimethoxymethylsilane, 3-amino-2-methylpropyltrimethoxysilane, 4-aminobutyltrimethoxysilane, 4-aminobutyldimethoxymethylsilane, 4-amino-3-methylbutyltrimethoxysilane, 4-amino-3,3-dimethylbutyltrimethoxysilane, 4-amino-3,3-dimethylbutyldimethoxymethylsilane, 2-aminoethyltrimethoxysilane, 2-aminoethyldimethoxymethylsilane, aminomethyltrimethoxysilane, aminomethyldimethoxymethylsilane, aminomethylmethoxydimethylsilane, N-methyl-3-aminopropyltrimethoxysilane, N-ethyl-3-aminopropyltrimethoxysilane, N-butyl-3-aminopropyltrimethoxysilane, N-cyclohexyl-3-aminopropyltrimethoxysilane, N N-phenyl-3-aminopropyltrimethoxysilane, N-methyl-3-amino-2-methylpropyltrimethoxysilane, N-ethyl-3-amino-2-methylpropyltrimethoxysilane, N-ethyl-3-aminopropyldimethoxymethylsilane, N-phenyl-4-aminobutyltrimethoxysilane, N-phenylaminomethyl-dimethoxymethylsilane, N-cyclohexylaminomethyl-dimethoxymethylsilane, N-methylaminomethyl-dimethoxymethylsilane, N-ethylaminomethyl-dimethoxymethylsilane, N-propylaminomethyl-dimethoxymethylsilane, N-butylaminomethyl-dimethoxymethylsilane; N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane, bis(trimethoxysilylpropyl)amine, and analogs thereof in which three ethoxy groups or three isopropoxy groups are placed on the silicon atom instead of the three methoxy groups.

[0055] In one embodiment, the aminosilane of formula (I) is an aminosilane of formula (V): H2N-R 5 -Si(OR 2 )(3-a) (R 3 ) a (V) [In the formula, R 5 is a linear or branched alkylene group having 1 to 6 carbon atoms, particularly propylene, and the other substituents and indices are as defined in formula (I). Particularly preferred herein is 3-aminopropyltrimethoxysilane.

[0056] In a preferred embodiment, the aminosilane of formula (I) has a secondary amino group, in particular an aminosilane of formula (VI) or (VII) or (VIII). [ka] [In the formula, R 5 is a linear or branched alkylene radical having 1 to 6 carbon atoms, in particular propylene, the other substituents and indices being as defined in formula (I). N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane, and bis(trimethoxysilylpropyl)amine have been found to be particularly suitable as organosilanes OS.

[0057] It has been found to be particularly advantageous when two or more aminosilanes of formula (I) are present in the composition as organosilanes OS, preferably at least one of which is an aminosilane of formula (VI). A particularly preferred combination among organosilanes OS is an aminosilane of formula (VI) with an aminosilane of formula (VIII) in the composition.

[0058] In one or more embodiments, the at least one aminosilane or hydrolysis product thereof is present in the composition of the invention after step d) in an amount of 0.5% to 5% by weight, preferably 1% to 4% by weight, particularly preferably 2% to 3% by weight, based on the total composition after step d).

[0059] In a preferred embodiment, the organosilane OS comprises at least one epoxysilane. Epoxysilanes suitable as organosilane OS have at least one epoxy group, e.g., a glycidoxy group, and at least one Si-bonded hydrolyzable group. The epoxy group is preferably a glycidoxy group or an epoxycyclohexyl group, especially a glycidoxy group.

[0060] Preferred epoxysilanes are (epoxyalkoxy)alkyltrialkoxysilanes and 3-glycidoxypropyltrialkoxysilanes. Particularly preferred is gamma-glycidoxypropyltrimethoxysilane. Preferred representatives of these types of substances are beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and beta-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and also 3-glycidoxypropyltrimethoxysilane and / or 3-glycidoxypropyltriethoxysilane. More preferably, 3-glycidoxypropyltrimethoxysilane and / or 3-glycidoxypropyltriethoxysilane are used as organosilanes OS.

[0061] In one or more embodiments, the at least one epoxysilane or hydrolysis product thereof is present in the inventive composition after step f) in an amount of 0.1% to 2% by weight, preferably 0.2% to 1.5% by weight, particularly preferably 0.5% to 1% by weight, based on the total composition after step d).

[0062] In a preferred embodiment, the organosilane OS includes at least one mercaptosilane.

[0063] Mercaptosilanes suitable as organosilanes OS have at least one mercapto group, such as a mercaptopropyl group, and at least one Si-bonded hydrolyzable group, and are preferably mercapto-functional organoalkoxysilanes, i.e., mercaptosilanes carrying C1-C4 alkoxy groups on the hydrolyzable silane group. Particularly preferred are mercapto-functional organomethoxysilanes and mercapto-functional organoethoxysilanes. Mercaptosilanes having three alkoxy groups, in particular three methoxy groups, have been found to be particularly advantageous.

[0064] Particularly preferred mercaptosilanes are 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-mercaptopropylmethyldimethoxysilane, especially 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane, more preferably 3-mercaptopropyltrimethoxysilane.

[0065] However, it is also possible to use mercaptosilanes which have multiple mercapto groups and / or multiple silane groups as organosilanes OS.

[0066] In one or more embodiments, the at least one mercaptosilane or hydrolysis product thereof is present in the inventive composition after step f) in an amount of 0.1% to 2% by weight, preferably 0.15% to 1.5% by weight, particularly preferably 0.5% to 1% by weight, based on the total composition after step d).

[0067] When the organosilane OS is a mixture of several organosilanes, and when the organosilanes are unlikely to cross-react with each other, they can be premixed and added simultaneously in step b).

[0068] In a particularly preferred embodiment of the process of the present invention, at least one mercaptosilane and at least one aminosilane are added in step b), which combination has particularly advantageous adhesion-promoting properties while being particularly storage-stable.

[0069] Upon contact with water during step e) or f), the organosilane OS is slowly or rapidly hydrolyzed. Even under optimized procedural conditions, a temporary precipitation may occur, resulting in a slightly cloudy solution; however, by adjusting the pH correctly in step c), particularly in the range between 2 and 5, this initial precipitation can be completely reversed within a short time (typically less than 10 minutes), and the solution will then become clear.

[0070] Optionally and preferably, in step b) at least one organotitanate OT is added in an amount of 0.01 to 0.8 parts by weight of titanium.

[0071] In step b), it is preferable to add between 0.1 and 5 parts by weight of at least one organotitanate OT in addition to the organosilane OS.

[0072] Optionally, but preferably, the organotitanate OT added in step b) is an organotitanate, particularly an alcohol-soluble, especially ethanol-soluble, organotitanate, or is capable of forming alcohol-soluble titanate species under acidic and / or hydrolytic conditions. The use of organotitanates in the pretreatment composition generally results in particularly thermally stable bonds that exhibit excellent bonding even at or below room temperature, and generally improves the adhesion-promoting performance of the resulting pretreatment composition, especially under hot weather conditions.

[0073] Suitable and preferred amounts of organotitanate OT or their hydrolysis products in the composition are preferably between 0.1% and 4% by weight, in particular between 0.5% and 3.5% by weight, most preferably between 1% and 3% by weight of organotitanate OT, based on the total composition after step d).

[0074] Suitable organotitanates OT are preferably of the formula Ti(OR)4, i.e., those containing substituents attached via oxygen-titanium bonds and further containing chelating substituents (multidentate ligands). Particularly suitable substituents attached to the titanium atom via oxygen-titanium bonds are those selected from the group comprising: alkoxy groups, sulfonate groups, carboxylate groups, aminoalkoxy groups, dialkylphosphate groups, dialkylpyrophosphate groups, and acetylacetonate groups.

[0075] Particularly suitable compounds for use as organotitanates OT are those in which all of the substituents attached to titanium are selected from the group including: alkoxy groups, sulfonate groups, carboxylate groups, aminoalkoxy groups, dialkylphosphate groups, dialkylpyrophosphate groups, and acetylacetonate groups, where all of the substituents may be the same or different.

[0076] Particularly suitable alkoxy groups have been found to be methoxy, ethoxy, propoxy, isopropoxy, butoxy, and isobutoxy substituents, among others.

[0077] Particularly preferred organotitanates OT have substituents selected from the following: alkoxy groups, in particular isopropoxy groups, and aminoalkoxy groups, in particular 2-(2-aminoethylamino)ethoxy groups, or mixtures of these substituents.

[0078] Most preferred as organotitanates OT are tetraalkoxy titanates, especially tetra-n-butyl titanate or tetra-isopropyl titanate.

[0079] Organotitanium compounds suitable for use as organotitanate OT are commercially available from, for example, Kenrich Petrochemicals or DuPont.

[0080] The most preferred organotitanate OT is tetra-n-butyl titanate or tetra-isopropyl titanate.

[0081] Optionally and preferably, in step b) at least one organozirconate OZ is added in an amount of 0.01 to 0.8 parts by weight of titanium.

[0082] In step b), it is preferable to add between 0.1 and 5 parts by weight of at least one organozirconate OZ in addition to the organosilane OS.

[0083] Organozirconates OZ are organozirconium compounds having at least one substituent attached to the zirconium atom via an oxygen-zirconium bond.

[0084] Suitable organozirconate OZ compounds are in particular those bearing at least one functional group selected from the group comprising alkoxy groups, sulfonate groups, carboxylate groups, phosphates, or mixtures thereof, and which is directly bonded to the zirconium atom via an oxygen-zirconium bond.

[0085] Organozirconate OZ compounds are commercially available, for example, from Kenrich Petrochemicals. Preferred are the tetraalkoxyzirconates, especially tetra-n-butyl zirconate.

[0086] Those skilled in the art will recognize that these organotitanate OT compounds and organozirconate OZ compounds undergo hydrolysis under the influence of water to form OH groups bonded to titanium or zirconium atoms. Such hydrolyzed or partially hydrolyzed organotitanium and organozirconium compounds can then further condense with themselves to form condensation reaction products having Ti-O-Ti and Zr-O-Zr bonds. When silanes and / or titanates and / or zirconates as adhesion promoters are mixed, mixed condensation reaction products having Si-O-Ti, Si-O-Zr, or Ti-O-Zr bonds may also be produced. Only a small portion of such condensation reaction products are produced, particularly when they are soluble, emulsifiable, or dispersible.

[0087] Step c) of the process according to the invention comprises adding an acid A to a mixture of alcohol, in particular ethanol, optionally water, organosilane OS and optionally organotitanate OT and optionally organozirconate OZ in such an amount that the resulting pH is between 3.5 and 7.

[0088] The pH achieved in the ethanolic composition after step c) is preferably between 4 and 6.5, in particular between 4.5 and 6. At this stage, it is recommended to measure the pH, for example using a pH meter or pH paper, and, if necessary, to adjust the pH to fall within the defined range by adding more acid A. The amount of acid required also depends on the type and amount of the components added in step b), since, for example, aminosilanes have alkaline functional groups and require additional acid to achieve the required pH.

[0089] The acid A can be organic or inorganic. The organic acid A is primarily a carboxylic acid, in particular a carboxylic acid selected from the group comprising: formic acid, acetic acid, propionic acid, trifluoroacetic acid, oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, and citric acid, and also amino acids, in particular aspartic acid and glutamic acid. A preferred carboxylic acid is acetic acid.

[0090] The organic acid A is secondly, in particular, one containing a sulfur atom. Such organic acids are in particular organic sulfonic acids. Organic sulfonic acids are understood to mean compounds having an organic group with a carbon atom and at least one functional group -SO3H. Aromatic sulfonic acids are preferred.

[0091] The aromatic sulfonic acid may be monocyclic or polycyclic and may have one or more sulfo groups present, for example, it may be naphthalene-1- or -2-sulfonic acid, naphthalene-1,5-disulfonic acid, benzenesulfonic acid, or alkylbenzenesulfonic acid.

[0092] Acid A may be an inorganic acid. Suitable inorganic acids A include, for example, those containing a sulfur atom or a phosphorus atom. Acids containing a phosphorus atom include, in particular, phosphoric acid, phosphorous acid, phosphonic acid, and phosphonous acid. Acids containing a sulfur atom include, in particular, sulfuric acid, sulfurous acid, persulfuric acid, disulfuric acid (=pyrosulfuric acid), disulfite, dithionic acid, dithionous acid, thiosulfuric acid, and thiosulfurous acid.

[0093] Most preferred are water-soluble or at least water-miscible acids A, especially those with a pKa between 4.0 and 5.0. a is a well-known method among chemists to calculate the acid dissociation constant K a The negative logarithm to the base 10 (pK a =-log 10 K a ) is understood to mean

[0094] The most preferred acids A are carboxylic acids, especially water-soluble carboxylic acids, especially acetic acid.

[0095] Once step c) is complete, step d) can begin, in which water is added in an amount at least equimolar or in excess relative to the molar amount of hydrolyzable silicon-, titanium-, and / or zirconium-bonded groups present in the total added organosilanes OS, organothionates OT, and organozirconates OZ, and in which the amount of water is at most 25 parts by weight.

[0096] The amount defining the lower end of the range (i.e., the above equimolar amount) should generally be calculated, at least roughly, based on the total Si—OR, Ti—OR, and Zr—OR groups theoretically present in the composition (wherein the term —OR refers to the hydrolyzable group on the Si, Ti, or Zr atom, respectively).

[0097] Calculation of the appropriate amount will be straightforward to one skilled in the art based on the molecular structure and amount of organosilane OS, organothionate OT, or organozirconate OZ, respectively, added.

[0098] Water should be added in an amount sufficient to completely hydrolyze all hydrolyzable species present in the composition. Using this approach, the resulting composition is highly active in adhesion-promoting pretreatments (including low-temperature applications) and is also less susceptible to further exposure to water in contact with the composition. Hydrolysis intended to produce Si-OH, Ti-OH, or Zr-OH groups within the composition will produce trialkoxysilane-functional compounds and Ti(OR) compounds, respectively, particularly when compounds containing -Si(OH) groups and, in some cases, but preferably, Ti(OH) groups are present.

[0099] In a preferred embodiment of the process of the present invention, the composition after step f) of the process contains between 0.2% and 2.0% by weight of Si(OH) groups, based on the total weight of the composition.

[0100] In a preferred embodiment of the process according to the invention, the composition after step f) of the process contains between 0.05% and 1.5% by weight of Ti(OH) groups, based on the total weight of the composition.

[0101] The water used in step d) is preferably deionized water, especially water obtained by either distillation or reverse osmosis using common processes known in the art.

[0102] Step d) can be carried out in a very easy manner and is completed in a few minutes, preferably with some stirring or shaking to ensure uniform mixing and to quickly dissipate any temporary precipitate or turbidity that may be present.

[0103] In a preferred embodiment of the process according to the invention, the amount of water added in step d) is between 0.3% and 2% by weight, based on the total composition after step d).

[0104] In another preferred embodiment of the process according to the invention, the amount of water added in step d) is between 0.3% and 15% by weight, based on the total composition after step d).

[0105] Step e) optionally includes adding further additives selected from colorants, UV markers, condensation catalysts, or stabilizers, or even other commonly added additives, into the activator pretreatment composition.

[0106] The additives added in step e) should not impair the storage stability of the composition. Common additional ingredients are, among others, catalysts, stabilizers, surfactants, acids, dyes, and pigments.

[0107] In some circumstances it may be advantageous to add to the composition in step e) a polyisocyanate or polyurethane prepolymer containing isocyanate groups.

[0108] However, it has been found to be advantageous that the compositions of the invention are isocyanate-free, i.e. no substances containing reactive NCO groups are added in step e).

[0109] As mentioned above, step e) is entirely optional. It may be advantageous to not add any further components after step d) because, without step e), the resulting composition after step f) is already a fully functional, highly active adhesion-promoting pretreatment that can be produced using only basic, low-cost components and has all the advantages of the present invention, including excellent storage stability.

[0110] Nevertheless, in a preferred embodiment, a silane condensation catalyst, particularly a water-soluble tin catalyst, is added to the composition during step e). Such catalysts are known to those skilled in the art of silane-based pretreatment compositions. The addition of the catalyst accelerates the condensation reaction of the active ingredients as soon as the pretreatment composition is applied to the surface, which is particularly useful when fast-curing adhesives are used and / or the ambient temperature during application is particularly low. Surprisingly, the addition of such a catalyst does not impair the storage or handling stability of the composition according to the present invention, as is the case with classical solvent-based adhesion promoters.

[0111] In a particularly preferred embodiment of the process according to the invention, the composition after step e) comprises, based on the total composition: - between 80% and 95% by weight of said alcohol, in particular ethanol; - between 1% and 3.5% by weight of organosilanes OS; - between 1% and 3.5% by weight of organotitanate OT; - between 0.3% and 2% by weight of acid A, in particular acetic acid; - between 0.3% and 15% by weight of water; and - optionally between 0.01% and 0.2% of a silane condensation catalyst, in particular a water-soluble tin catalyst; (wherein the organosilanes OS and organotitanates OT may be partially or fully hydrolyzed by water in the composition).

[0112] Such compositions are particularly suitable as pretreatment compositions and adhesives for AGR applications that are not affected by ambient climatic conditions, while also being highly reactive and offering high performance as adhesion-promoting pretreatment compositions, while also being stable in handling and storage.

[0113] Another aspect of the present invention is an adhesion-promoting pretreatment composition obtainable by the process of the present invention described above, wherein all added organosilanes OS, and optionally added organotitanates OT, and optionally added organozirconates OZ are fully hydrolyzed.

[0114] A further aspect of the present invention is the use of an adhesion promoting pretreatment composition according to the present invention as an adhesion promoter or activator, as will be more particularly described below.

[0115] In particularly preferred embodiments, such as those used in the present invention, at least one of the substrates treated with the adhesion promoting pretreatment composition is a glass or glass-ceramic substrate, particularly in automotive glass repair applications.

[0116] For use in the present invention, polyurethane adhesives or adhesives based on silane-functional polymers are particularly used, including silicones (polydimethylsiloxanes) and organosilane-functional polymers, such as so-called MS polymers, silane-functional polyurethanes, and other silane-functional organic polymers.

[0117] The compositions obtained using the process of the present invention are particularly one-component adhesion-promoting pretreatment compositions. When used in this sense as a pretreatment composition, the compositions improve the adhesion of adhesives onto substrates.

[0118] It has now been found that the adhesion-promoting pretreatment compositions of the present invention can be used exceptionally efficiently to produce adhesive undercoats on substrates S1 at low substrate temperatures, i.e., below 5° C. In addition, it has also been found that excellent adhesive undercoats are achievable at substrate temperatures between 0° C. and −20° C., preferably between −5° C. and −15° C.

[0119] In a further aspect, the present invention also relates to a process for producing a substrate S1 coated with an adhesion-promoting pretreatment composition according to the present invention, comprising the following steps: Applying an adhesion promoting pretreatment composition as described above to a substrate S1 having a temperature below 5°C, in particular between 0°C and -20°C, preferably between -5°C and -15°C.

[0120] Possible substrates S1 are, in principle, most natural or synthetic substrates. If necessary, they can be pretreated before applying the adhesion-promoting pretreatment composition. Such pretreatments include, in particular, physical and / or chemical cleaning methods, such as polishing, sandblasting, or brushing; or treatment with detergents or solvents; or application of additional adhesion promoters, additional adhesion promoter solutions, or primers; flame or plasma treatment, in particular air plasma pretreatment at atmospheric pressure.

[0121] More specifically, the substrate S1 is a mineral substrate, a plastic substrate, or a metal substrate.

[0122] Preferred mineral substrates are especially glass or glass ceramics, especially in the form of window panes.

[0123] Preferred plastics are in particular polyvinyl chloride (PVC), polyurethanes, poly(meth)acrylates, especially in the form of coatings or paints.

[0124] Metal substrates are understood in this specification to mean metals, metal alloys and coated metals and metal alloys, particularly light metals, non-ferrous metals and ferrous metals and their alloys, such as aluminum, iron, copper, zinc and their alloys, especially brass and steel.

[0125] The adhesion promoting pretreatment composition can be applied by cloth, felt, roller, sprayer, sponge, brush, dip, or other means, both manually and robotically.

[0126] An adhesive can be applied to the substrate coated in this way using the adhesion-promoting pretreatment composition. Thus, in a further aspect, the invention also relates to a process for adhesively bonding two substrates S1 and S2. For this purpose, various possibilities exist: in a first variant, the following steps are involved: a) applying an adhesion-promoting pretreatment composition as described above to a first substrate S1 having a temperature below 5°C, in particular between 0°C and -20°C, preferably between -5°C and -15°C; b) applying an adhesive to the adhesion-promoting pretreatment composition applied and flashed off in step a); c) contacting the adhesive with a second substrate S2.

[0127] In a second variant, the following steps are included: a') applying an adhesion-promoting pretreatment composition as described above to a first substrate S1 having a temperature below 5°C, in particular between 0°C and -20°C, preferably between -5°C and -15°C; b') applying an adhesive or sealant to the surface of the second substrate S2; c') contacting the adhesive with the flashed-off composition present on the substrate S1;

[0128] In a third variant, the following steps are included: a") applying an adhesion-promoting pretreatment composition as described above to a first substrate S1 and / or a second substrate S2 having a temperature below 5°C, in particular between 0°C and -20°C, preferably between -5°C and -15°C; b") applying an adhesive to the first substrate S1 and the second substrate S2 (at least one of which has had the adhesion-promoting pretreatment composition applied to it in step a"); c”) Bringing the applied adhesive into contact with each other and overlapping the substrate parts to form an adhesive bond.

[0129] In a fourth variant, the following steps are included: a"') applying an adhesion promoting pretreatment composition as described above to a first substrate S1 having a temperature below 5°C, in particular between 0°C and -20°C, preferably between -5°C and -15°C; b"') flashing off the composition; c''') Applying adhesive between the surfaces of substrate S1 and substrate S2.

[0130] In these four variants, the second substrate S2 consists of the same or a different material as the substrate S1.

[0131] Substrate S1 and / or substrate S2 may be of various types. Possibilities for the second substrate S2 may be those listed above for substrate S1. More specifically, at least one of substrate S1 or substrate S2 is glass or glass ceramic. More specifically, one substrate is glass or glass ceramic, and the other substrate is painted, painted metal, or painted metal alloy. Thus, substrate S1 or substrate S2 is glass or glass ceramic, and substrate S2 or S1 is painted, painted metal, or painted metal alloy.

[0132] Steps c), c'), c") or c'') are typically followed by step d), in which the adhesive is cured. Those skilled in the art will understand that, depending on the system and the reactivity of the adhesive used, the crosslinking reaction, and therefore curing, may already begin during application. However, the main part of the crosslinking and (in the narrower sense of the term) curing occurs after application, otherwise problems with establishing a bond to the substrate surface may arise.

[0133] Adhesives that can be used are various adhesive systems, more particularly moisture-curing adhesives based on prepolymers terminated with isocyanate groups and / or alkoxysilanes.

[0134] Suitable adhesives based on alkoxysilane-terminated prepolymers are: one-component moisture-curing adhesives (so-called MS polymers) or alkoxysilane-terminated polyurethane prepolymers, especially those prepared from polyols and, if desired, polyisocyanates, which are then reacted with isocyanate-reactive or isocyanate-functional organosilanes.

[0135] Suitable adhesives based on isocyanate-terminated prepolymers are primarily understood to mean two-component polyurethane adhesives, the first component of which comprises an amine or polyol and the second component of which comprises an NCO-containing prepolymer or polyisocyanate. Examples of such two-component room-temperature-curing polyurethane adhesives are those in the SikaForce® product line, available commercially from Sika Schweiz AG.

[0136] Suitable adhesives based on isocyanate-terminated prepolymers are also understood to mean reactive polyurethane hot melt adhesives, which contain a thermoplastic polymer and an isocyanate-terminated prepolymer, or a thermoplastic isocyanate-terminated prepolymer. Such reactive polyurethane hot melt materials are melted and first solidify during cooling, then crosslink by reaction with atmospheric moisture.

[0137] Suitable adhesives based on isocyanate-terminated prepolymers are also understood to mean one-component moisture-curing polyurethane adhesives. Such adhesives or sealants crosslink under the influence of moisture, especially atmospheric moisture. Examples of such one-component moisture-curing polyurethane adhesives are those from the SikaFlex® and SikaTack® product lines, commercially available from Sika Schweiz AG.

[0138] The above-mentioned isocyanate-terminated prepolymers are prepared from polyols, particularly polyoxyalkylene polyols, and polyisocyanates, particularly diisocyanates.

[0139] Preferred are adhesives based on isocyanate-terminated prepolymers, and most preferred are one-component moisture-curing polyurethane adhesives based on isocyanate-terminated prepolymers.

[0140] It has been found that, particularly in the case of moisture-curing polyurethane adhesives or sealants, using the aforementioned compositions, a significant improvement in adhesion can be achieved, particularly at low temperatures, i.e., particularly at temperatures below 5° C., and especially between 0° C. and −20° C. Water-based compositions are obviously unsuitable for application temperatures below 0° C. due to freezing.

[0141] These bonding methods find particular application in the manufacture of industrially manufactured articles, especially transportation vehicles, such as automobiles, buses, trucks, rail cars, ships and aircraft, among others.

[0142] The most preferred application is in the glazing of vehicles, especially road and rail vehicles.

[0143] Because of the significant improvement in adhesive and sealant adhesion at low temperatures, the process is particularly suitable for glazing repair (also known as automotive glass repair (AGR) operations). Specifically, it is possible to glaze a vehicle on-site, especially in winter, without the need to place the vehicle in a climate-controlled garage at the start. This is particularly important when repairing vehicle glazing in remote areas (particularly where roads often have loose stones and gravel). Such areas are common, for example, in Scandinavia, Russia, China, Argentina, Chile, Canada, or the United States. The adhesive undercoat composition is particularly suitable for a process for repairing glazing on vehicles, especially automobiles, at ambient temperatures below 5°C, especially between 0°C and -20°C, preferably between -5°C and -15°C, which comprises the following steps: i) removing defective glass, in particular defective window glass; ii) applying an adhesion-promoting pretreatment composition as described above to a piece of glass, in particular a window pane, to be adhesively joined and / or to a flange portion of the vehicle to be adhesively joined; iii) applying a moisture-curing one-component adhesive, in particular a moisture-curing one-component polyurethane adhesive, having a temperature between 10°C and 80°C, in particular about 23°C, to the glass pieces to be adhesively joined and / or to the flanges of the means of transport to be adhesively joined; iv) joining the glass and flange with the adhesive therebetween;

[0144] It has been found that by means of this process, it is possible to glaze a vehicle in situ on the road during cold conditions, often occurring in winter, without the need to place the vehicle in a climate-controlled garage to begin with. This is particularly important when repairing vehicle windows in remote areas (especially where street stones and gravel are often not compacted), such as are often found in Scandinavia, Russia, China, Argentina, Chile, Canada, or the United States.

[0145] Because the adhesion-promoting pretreatment composition of the present invention promotes adhesion at higher temperatures, i.e., temperatures above 5°C, typically from about room temperature (23°C) to about 45°C or higher, one and the same adhesion-promoting pretreatment composition can be used, thereby eliminating the need for different handling modes for summer and winter products depending on the season. [Example]

[0146] The present invention is further illustrated by the following examples, which are not intended to limit the invention in any way.

[0147] Raw materials used The following raw materials listed in Table 1 were used as purchased without any purification or modification and employed in the process of the present invention to produce examples of adhesion-promoting pretreatment compositions to demonstrate the effectiveness of the present invention.

[0148] [Table 1]

[0149] Preparation of Example Compositions C1 to C22 Example compositions C1 to C22 were produced using the raw materials listed in Table 1, following the steps listed below in the order indicated. The detailed compositions of compositions C1 to C22 are shown in Tables 2 to 5. In each table, the numerical values ​​indicate the amount (unit: parts by weight) of each raw material / component added. In Tables 2 to 5, compositions that are not of the present invention are marked with an asterisk (*).

[0150] The following process was carried out indoors under standard climatic conditions (23° C., 50% relative humidity) without heating the reaction vessel. Step a) An open glass beaker equipped with a magnetic stirrer was charged with the specified amount of ethanol and, if necessary, additional solvent. Step b) In each experiment, all of the organosilane OS, organotitanate OT, and / or organozirconate OZ raw materials were added stepwise under stirring in the amounts listed in Tables 2-5, respectively. Step c) In each experiment, Acid A was added in the amount listed in Tables 2-5, respectively. Step d) In each experiment, water was added in the amounts listed in Tables 2-5, respectively. Step f) The mixture so obtained was left under stirring at 23° C. for at least 30 minutes, resulting in a homogeneous solution.

[0151] Each composition was then filled into a sealable glass container and used as an adhesion-promoting pretreatment composition for adhesion testing and / or in artificial aging tests to assess storage stability.

[0152] [Table 2]

[0153] [Table 3]

[0154] [Table 4]

[0155] [Table 5]

[0156] Test Protocol The example compositions C1 to C22 were tested as follows.

[0157] To evaluate storage stability, example compositions C1 to C22 were subjected to a simulated aging test under heat. For this, a sealed glass bottle of each composition was placed in an oven (50°C) and left under these conditions for two years. The samples were checked weekly for any obvious changes (precipitation, gelation, etc.). Samples C11 to C22 were produced more recently, so no long-term data are available. Samples that showed no change in terms of gelation, precipitation, or other deterioration after at least 21 days at 50°C were considered storage stable.

[0158] [Table 6]

[0159] Adhesion Test Protocol This test protocol investigated the adhesion-promoting capabilities of the compositions of the examples (both inventive and non-inventive reference examples) prepared by the process described above, and also of two commercially available solvent-based activators as references to the state of the art.

[0160] The adhesive used in this test protocol was SikaTack® ELITE, a commercially available one-component moisture-curing polyurethane adhesive containing a polyurethane prepolymer with isocyanate groups, available from Sika Schweiz AG.

[0161] Additional reference adhesion promoting pretreatment compositions (state of the art, currently used activators) used were: "MP-A", a multipurpose solvent-based activator ("MP-A") particularly suited for glass and ceramic substrates; and "AGR-A", a solvent-based activator optimized for AGR applications, including low-temperature glass replacement ("AGR-A"). Both reference activators MP-A and AGR-A were prepared by adding the respective silanes to the respective solvents. The detailed components and their amounts (units, parts by weight) are shown in Table 7 below:

[0162] [Table 7]

[0163] The substrates used were: "Glass (air)": float glass (air side used in adhesion tests, Rocholl, Germany); "Glass (tin)": float glass (tin side used in adhesion tests, Rocholl, Germany); "Frit 3402": ESG ceramic, Ferro AD 3402, Rocholl, Germany; "Ferro 14279": VSG ceramic, Ferro 14279, Rocholl, Germany; "Ferro 14303": VSG ceramic, Ferro 14303 IR7134, Rocholl, Germany.

[0164] All surfaces of the substrates were cleaned immediately prior to application of the adhesion promoter compositions by wiping with a cellulose cloth (Tela®) that had been soaked in isopropanol and allowed to evaporate for at least 2 minutes prior to application of each adhesion promoting pretreatment composition to be tested.

[0165] The compositions to be tested were applied to the substrates by means of a soaked cellulose cloth (Tela®, Tela-Kimberly Switzerland GmbH) and allowed to stand for a flash-off period of 5 minutes, after which the adhesive was applied onto the thus-pretreated surface ("wipe-on" application). The substrates were in most cases conditioned at 23°C before application of the compositions, but in some cases were conditioned at 5°C instead to study low temperature application behavior. The detailed application conditions for each experiment are given in Tables 7 to 11.

[0166] A triangular bead of adhesive was applied by means of an extrusion cartridge and nozzle at 23±2° C. and 50% relative humidity. The adhesive itself was allowed to equilibrate in the closed cartridge at 23° C. for 24 hours before application.

[0167] The adhesive-cured joints were tested after a cure time determined for each experiment (Tables 7-11) between 45 minutes and 7 days (e.g., "45 min RT") under controlled weather conditions (23°C, 50% relative humidity) or were cured by immersion in water for 7 days to assess the water stability of the adhesive joints ("7d water").

[0168] The adhesive adhesion was tested by means of a "bead adhesion test." This involves making an incision in a bead at the end just above its joining surface. The incised end of the bead is grasped with rounded tweezers and pulled away from the substrate. This is done by carefully rolling the bead up toward the tip of the tweezers, with the incision perpendicular to the direction of bead withdrawal relative to the bare substrate. The bead pulling speed must be selected so that an incision is made approximately every 3 seconds. The test distance must correspond to at least 8 cm. This assesses the adhesive remaining on the substrate after the bead has been completely pulled away (cohesive failure). Adhesion performance is assessed by visually measuring the cohesive fraction of the bonded area.

[0169] In this test protocol, the amount of cohesive failure (in % based on the total failure pattern) was evaluated and expressed as a numerical value (0% CF to 100% CF, where "CF" stands for "cohesive failure").

[0170] The higher the percentage of cohesive failure, the better the adhesive bond is rated. Ideally, a bond would exhibit 100% CF.

[0171] These adhesion tests for the adhesion-promoting pretreatment compositions tested on each test substrate are shown in Tables 8-12.

[0172] [Table 8]

[0173] [Table 9]

[0174] [Table 10]

[0175] Tables 8-10 show that compositions according to the present invention exhibit improved adhesion promotion effects on the tested substrates compared to similar compositions not according to the present invention. Compared to a commercially available benchmark activator (MP-A), compositions according to the present invention perform at least as well, if not better, under ambient curing conditions. With regard to adhesion results in water, compositions according to the present invention have clearly improved performance compared to the commercial activator.

[0176] [Table 11]

[0177] The results in Table 11 demonstrate that the example composition C10 according to the invention provides exceptionally good adhesion both in the short term (1 hour) and in the long term (7 days) compared to the commercial (AGR-A) and reference composition (C11). Again, the composition according to the invention is particularly outstanding in terms of the water resistance of its adhesive bond.

[0178] [Table 12]

[0179] In Table 12, the composition of the present invention (C12) is compared with two commercially available activators in relation to their low temperature applications. As can be seen, the composition of the present invention slightly exceeds the performance of AGR-A, an activator optimized for AGR applications, regardless of temperature.

[0180] Adhesion Testing with Aged Adhesion-Promoting Pretreatment Compositions Additional adhesion tests were carried out using Example Composition C10 (one freshly prepared sample and one sample aged by leaving the bottle open for 40 minutes at 35°C and 80% relative humidity). As a reference, AGR-A (see above) was used, but both fresh and artificially aged samples were also employed.

[0181] These adhesion tests were carried out on the following samples: "Glass (air)": float glass (air side used in adhesion tests, Rocholl, Germany); "Glass (tin)": float glass (tin side used in adhesion tests, Rocholl, Germany).

[0182] The adhesive used was SikaTack® PRO, a one-component polyurethane adhesive for AGR applications available from Sika Schweiz.

[0183] The adhesion tests were performed as described above in the first adhesion test protocol, except that the adhesive bonds were cured in an oven at 80°C for 1 day before the adhesion test was also performed ("1d 80°C").

[0184] The results are shown in Table 13.

[0185] [Table 13]

[0186] The results shown in Table 13 demonstrate that the compositions of the invention do not lose their performance after aging and exhibit the same adhesion promoting effect as in the fresh state, regardless of the application temperature and cure conditions of the adhesive bond, whereas the reference composition shows some loss of performance after artificial aging.

Claims

1. 1. A process for preparing an adhesion-promoting pretreatment composition comprising: a) providing a reaction vessel containing 100 parts by weight of an alcohol having 1 to 4 carbon atoms; b) adding at least one organosilane OS in an amount to add between 0.15 and 0.8 parts by weight of silicon, optionally adding at least one organothionate OT in an amount to add between 0.01 and 0.8 parts by weight of titanium, and optionally adding at least one organozirconate OZ in an amount to add between 0.01 and 0.8 parts by weight of zirconium; c) adding acid A in an amount such that the resulting pH is between 3.5 and 7; d) adding water, the amount of water being at least equimolar or in excess relative to the molar amount of hydrolyzable silicon-, titanium-, and / or zirconium-bonded groups present in the total added organosilane OS, organothiocyanate OT, and organozirconate OZ, wherein the amount of water is at most 25 parts by weight; e) optionally adding further additives selected from colorants, UV markers, condensation catalysts, or stabilizers; f) waiting, optionally with stirring, shaking and / or heating, until all hydrolyzable groups present in all added organosilanes OS, organothionates OT and organozirconates OZ have been hydrolyzed; A process involving:

2. 2. The process according to claim 1, characterized in that the acid A in step c) is a carboxylic acid or an alkylsulfonic acid, preferably acetic acid or methanesulfonic acid, in particular acetic acid.

3. 3. The process according to claim 1 or claim 2, characterized in that the organosilane OS comprises at least one organosilane or condensate thereof having at least one Si-bonded hydrolyzable group and having at least one primary and / or secondary amino group.

4. 4. The process according to claim 1, wherein the organosilane OS comprises an organosilane or an oligomer of such an organosilane having at least one Si-bonded hydrolyzable group and having at least one further functional group bonded to the silicon atom via at least one carbon atom and optionally an ether oxygen or nitrogen atom, said functional group being selected from alkyl, alkylene, phenyl, epoxy, mercapto, hydroxyl, (meth)acrylate, isocyanate, anhydride, silane, and isocyanurate groups.

5. 5. The process according to claim 1, wherein the organotitanate OT is a tetraalkoxytitanate, in particular tetra-n-butyl titanate or tetra-isopropyl titanate.

6. 6. The process according to claim 1, wherein the organozirconate OZ is a tetraalkoxyzirconate, in particular tetra-n-butylzirconate.

7. 7. The process according to any one of claims 1 to 6, characterized in that the alcohol having 1 to 4 carbon atoms is ethanol.

8. 8. The process according to claim 1, wherein in step c) acid A is added in an amount such that the resulting pH is between 4 and 6.5, in particular between 4.5 and 6.

9. 9. The process according to any one of claims 1 to 8, characterized in that in step d) the amount of water added is between 0.3% and 15% by weight, based on the total composition after step d).

10. 10. The process according to any one of claims 1 to 9, characterized in that in step e) a silane condensation catalyst, in particular a water-soluble tin catalyst, is added.

11. The composition after step e) comprises, based on the total composition: between 80% and 95% by weight of said alcohol, in particular ethanol; between 1% and 3.5% by weight of organosilane OS; between 1% and 3.5% by weight of organotitanate OT; between 0.3% and 2% by weight of an acid A, in particular acetic acid; between 0.3% and 15% by weight of water; and optionally between 0.01% and 0.2% of a silane condensation catalyst, in particular a water-soluble tin catalyst; Including, 11. The process according to claim 1, wherein the organosilanes OS and organotitanates OT may be partially or completely hydrolyzed in the composition by the water.

12. 12. An adhesion promoting pretreatment composition obtainable from the process of any one of claims 1 to 11, wherein all of the added organosilane OS and optionally added organotitanate OT, and optionally added organozirconate OZ are fully hydrolyzed.

13. 13. Use of the adhesion promoting pretreatment composition of claim 12 as an adhesion promoter or activator.

14. 14. The use of claim 13, wherein at least one of the substrates treated with the adhesion promoting pretreatment composition is a glass or glass-ceramic substrate, particularly in automotive glass repair applications.

15. 15. Use according to claim 13 or 14 in conjunction with a polyurethane adhesive or an adhesive based on a silane-functional polymer.

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