Large area bonding adhesive

Abstract

A sprayable aerosol adhesive formulation, the sprayable aerosol adhesive formulation comprising, based on the total weight of the sprayable aerosol adhesive formulation: 1) A bulk adhesive formulation comprising: a) 10-80 wt%, preferably 10-65 wt%, more preferably 10-40 wt%, most preferably 15-35 wt% of silyl modified polymer compounds; b) 0.5-5 wt%, preferably 0.8-3.5 wt% of at least one adhesion promoter; c) 0.5-5 wt%, preferably 0.8-3.5 wt% of at least one dehydrating agent; d) optionally 0-30 wt%, preferably 5-25 wt% of at least one plasticizer compound; e) optionally 0-60 wt% preferably 15-55 wt% and more preferably 30-50 wt% of at least one filler, f) optionally 0-20 wt%, preferably 1-15 wt% and even more preferably 2-10 wt% of at least one non-reactive diluent, and 2) A propellant comprising at least 70 wt% of a dimethyl ether propellant and optionally further comprising up to 30 wt% of butane, propane, isobutane, hydrofluorocarbon (HFC), hydrofluoro- oleofin (HFO),dry air, nitrogen or a combination based on the total weight of the propellant wherein based on the total weight of all silyl modified polymer compounds in the formulation, 80-100 wt%, preferably 90-100 wt% of the silyl modified polymer compounds have a viscosity in the range of 0,2 Pa.s to 8 Pa.s, preferably in the range of 0,4 Pa.s to 8 Pa.s, more preferably between 0.4 Pa.s and 5 Pa.s, and wherein the bulk adhesive formulation has a viscosity in the range of 0.1 Pa.s to 8 Pa.s, preferably 1 Pa.s to 7 Pa.s, more preferably in the range of 1.5 Pa.s to-6 Pa.s (the viscosity measured according to ISO 3219-2 in a plate – plate configuration at 200 micron gap after 24 hours at a shear rate of 10 s-1 and at room temperature), and wherein the bulk adhesive formulation comprises 2-10 wt% of at least one non-reactive diluent in case the bulk adhesive formulation comprises ≥ 15 wt% of at least one filler, and wherein at least 50 wt% of the silyl modified polymer compounds are silyl modified polyether compounds based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation, and wherein the weight ratio of the bulk adhesive formulation to propellant is between 40:60 to 90:10.

Description

[0001] Title: LARGE AREA BONDING ADHESIVE

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The present invention relates to an adhesive formulation suitable for spraying applications, more in particular suitable for making a spray able aerosol adhesive and to a spray able adhesive system.

[0004] BACKGROUND OF THE INVENTION

[0005] Adhesives and sealants suitable for the construction industry are known in the art. Typical construction glues are based on polyurethane (PU), silicone, acrylic, ethers, silyl terminated polymers or combinations thereof. The aforementioned glues are known to have a high viscosity which limits the dispensing speed and the covered area of the adhesive. As such, glues like polyurethane, silicone, acrylic or hybrid combinations are less likely to be used for large area applications. The high viscosity of the glues is related to the high amount of fillers; in certain example more than 50 wt%, based on the total weight of the glue, is related to at least one filler. To apply the high viscous glues, special pistols are designed, allowing proper application of the glue.

[0006] To bypass the lack of area coverage, adhesive systems like sprayable foam adhesives and contact adhesives have been introduced. Sprayable foam adhesive will increase the surface area upon activation of a foaming agent resulting in expansion and hence an increase in area coverage. While the area coverage increases compared to glues, applied via a pistol, the overall area increase is limited. Further spray able foam adhesives are often based on PU-chemistry comprising in most instances diisocyanate compounds which nowadays are considered a health risk and hence to be avoided. Contact adhesives are typically composed of rubber technology combined with at least one solvent to reduce the viscosity to an optimal level to allow spraying of the contact adhesive. Contact adhesives have the disadvantage that a limited amount of fillers can be used limiting the possibility to formulate the contact adhesive for more demanding applications, particularly with respect to strength.

[0007] Additionally, because of the higher amounts of solvents in contact adhesive, contact adhesives in general need at least 15 minutes to dry before applying a second substrate. Furthermore, solvents in general release Volatile Organic Compounds (VOC’s) when drying such that contact adhesives are considered less environmental friendly. While water-based contact adhesives are available on the market, they have beside an higher drying time due to the lower volatility of water inferior adhesive properties compared to solvent based contact adhesives.

[0008] WO20 17052373 Al describes an improved silyl modified terminated polymer used in a sealant in combination with specific antioxidants. The sealant described herein refers to a glue having a high viscosity and hence not suitable for sprayable applications.

[0009] EP2970584 Bl describes a bond adhesive composition comprising a polymer having a silicon-containing hydrolysable terminal group and a hydrocarbon resin which is substantially devoid of phenolic acid (more in particular formal aldehyde). The composition in EP2970584 Bl may comprise fillers but fillers are omitted when a sprayable composition is intended and hence properties like, for example, strength can only be modified until a certain limit.

[0010] WO2022098844 Al describes an adhesive formulation comprising high viscosity silyl modified polymer. The formulation further comprises a moisture scavenger, an adhesion promoter, a catalyst, a filler, a plasticizer, an antioxidant or any combination thereof. Referring to the high viscosity formulation, the described adhesive cannot be used for sprayable applications.

[0011] As such there is a need for an adhesive formulation suitable for use as a spray able formulation, more in particular for making a spray able aerosol adhesive that can cover a large area while limiting the drying time, lowering the volatile organic content and preferably avoiding the use of solvents. Further, the adhesive formulation should allow easy dispensing and optionally contain fillers so as to be able to modify properties such as strength.

[0012] SUMMARY

[0013] The current invention provides an adhesive formulation suitable for spray able applications, more in particular for making a sprayable aerosol adhesive wherein the adhesive formulation does not contain or has negligible amounts of solvent thereby drastically lowering the VOC-content.

[0014] Further the adhesive formulation according to the present invention can easily cover a large area as it can be sprayed. It was further surprisingly found that the sprayable aerosol adhesive formulation of the invention may further comprise fillers to enhance the strength of said adhesive formulation and will result in a stable and sprayable formulation over time.

[0015] According to the invention, a bulk adhesive formulation with a low base viscosity and a broad adhesion spectrum is provided. The low viscosity and broad adhesion spectrum result in an adhesive with a good adhesion to multiple substrates such as EPDM, steel, aluminum, wood, stone, PVC. A low viscosity of the bulk adhesive formulation leads to an adhesive that is sprayable initially but also after aging. To obtain such bulk adhesive formulation, a selection of proper polymers (silyl modified polymer) is made. Fillers are optionally added to influence the adhesion properties to address more demanding applications. Accordingly the invention provides a bulk adhesive formulation suitable for making a sprayable aerosol adhesive formulation, said bulk adhesive formulation comprising, based on the total weight of the bulk adhesive formulation: a) 10-80 wt %, preferably 10-65 wt %, more preferably 10-40 wt%, most preferably 15-35 wt % of silyl modified polymer compounds; b) 0.5-5 wt %, preferably 0.8-3.5 wt % of at least one adhesion promoter; c) 0.5-5 wt %, preferably 0.8-3.5 wt % of at least one dehydrating agent; d) optionally 0-30 wt %, preferably 5-25 wt % of at least one plasticizer compound; e) optionally 0-60 wt %, preferably 15-55 wt %, more preferably 30-50 wt % of at least one filler; f) optionally 0-20 wt %, preferably 1-15 wt %, more preferably 2- 10 wt % of at least one non-reactive diluent, and wherein based on the total weight of all silyl modified polymer compounds in the formulation, 80-100 wt %, preferable 90-100 wt % of the silyl modified polymer compounds have a viscosity in the range 0.2 Pa.s to 8 Pa.s, preferably in the range of 0.4 Pa.s and 5 Pa.s and wherein the bulk adhesive formulation according to the invention has a viscosity in the range of 0.1 Pa.s to 8 Pa.s, preferably 1 Pa.s to 7 Pa.s, more preferably in the range of 1.5 Pa.s to 6 Pa.s, wherein the bulk adhesive formulation comprises 2-10 wt% of at least one non-reactive diluent in case the bulk adhesive formulation comprises > 15 wt% of at least one filler, and wherein at least 50 wt% of the silyl modified polymer compounds are silyl modified polyether compounds based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation.

[0016] The silyl modified polymers may comprise silyl modified polyurethane compounds, silyl modified polyether compounds, silyl modified acrylic polymer compounds, or a combination thereof, provided that the silyl modified polymers comprise at least 50 wt%, more preferably at least 75 wt%, most preferably at least 90 wt% silyl modified polyether compounds based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation, the remaining silyl modified polymers preferably selected from silyl modified acrylic polymer compounds.

[0017] According to preferred embodiments, the silyl modified polymers comprise silyl modified polyether compounds and silyl modified acrylic polymer compounds, provided that the silyl modified polymers comprise at least 50 wt%, more preferably at least 75 wt%, most preferably at least 90 wt% silyl modified polyether compounds based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation.

[0018] According to preferred embodiments, the silyl modified polymers are selected from silyl modified polyether compounds.

[0019] The filler that can be used according to the invention generally has a density in the range of 0.1-6 g / cm3, preferably 0.3-5 g / cm3, more preferably 0.4-4 g / cm3, most preferably between 0.5-3 g / cm3.

[0020] The bulk adhesive formulation may further comprise additive compounds in an amount, based on the total weight of the formulation, of 0- 50 wt %, preferably 0-30 wt %, more preferably 0-15 wt %. The additive compound may be selected from a pigment, a dye, a stabilizer, a catalyst, a rheology control agent, a tackifier, a natural resin (including natural fats and oils), a flame retardant, a surface -active substance, a biocide or a combination thereof.

[0021] Furthermore, the present invention is directed to a spray able aerosol adhesive comprising the bulk adhesive formulation and a propellant wherein the propellant comprises at least 70 wt % of a dimethyl ether and optionally further comprising up to 30 wt % of butane, propane, isobutane, hydrofluorocarbons (HFC), hydrofluoro-olefins (HFO), dry air, nitrogen or a combination thereof based on the total weight of the propellant. Preferably the propellant comprises at least 80 wt %, more preferably at least 90 wt % of a dimethyl ether. The weight ratio of the bulk adhesive formulation to propellant is between 40:60 to 90:10, preferably between 55:45 to 85:15, more preferably between 70:30 to 80:20. The sprayable aerosol adhesive generally has a density between 0.8- 1.3 g / cm3.

[0022] Moreover, the present invention is further directed to a sprayable aerosol adhesive system preferably selected from a cannister, a nozzle aerosol spray can or an inverted aerosol can comprising the sprayable aerosol adhesive.

[0023] Additionally, the present invention relates to the use of the sprayable adhesive system, the use comprising at least the steps of: a) spraying the sprayable aerosol adhesive according to the invention on at least a first surface of a first substrate to achieve a coated first substrate; b) providing a second substrate; c) optionally spraying the sprayable aerosol adhesive according to the invention on at least one surface of the second substrate to achieve a coated second substrate; d) applying the second substrate which is optionally coated on said coated first substrate. wherein the sprayed aerosol adhesive within 5 minutes after spraying has a tack value between 0.02 N / cm2and 5 N / cm2, preferably between 0.1 N / cm2and 3.5 N / cm2and wherein a permanent bond is reached within 15 to 1500 minutes, preferably between 30 and 500 minutes and more preferably between 45 and 250 minutes after spraying the sprayable adhesive onto said first substrate. Preferably, the sprayable aerosol adhesive system has a tack value between 4 N / cm2and 12 N / cm2within 10 to 90 minutes and a permanent bond is reached within 15 to 1500 minutes, preferably within 30 to 500 minutes, more preferably within 45 to 250 minutes.

[0024] Additionally, the current invention is directed to a method of making the sprayable system, the method comprising at least the following steps: a) mixing at least one silyl modified polymer, at least one dehydrating agent, at least one adhesion promoter, optionally at least one plasticizer compound, optionally at least one filler and optionally additives, b) optionally further adding at least one non-reactive diluent to further reduce the viscosity to form a bulk adhesive formulation having a viscosity in the range of 0.1 Pa.s to 8 Pa.s, preferably 1 Pa.s to 7 Pa.s, more preferably 1.5 Pa.s to 6 Pa.s, c) filling the system with the bulk adhesive formulation obtained in foregoing steps, d) adding a propellant comprising at least one propellant compound wherein (based on the total weight of the propellant) the propellant comprises at least 70 wt%, preferably at least 80 wt%, more preferably at least 90 wt% of a dimethyl ether and optionally further comprising up to 30 wt% of butane, propane, isobutane, hydrofluorocarbon (HFC), hydrofluoro-olefin (HFO), dry air, nitrogen or a combination thereof to the filled system to form a sprayable aerosol adhesive having a density between 0.8-1.3 g / cm3.

[0025] Contrary to the prior art, the current invention does not require any solvents or volatile organic compounds released during the drying of the adhesive system. The absence or low amount of solvents as well as volatile organic compounds make the bulk adhesive formulation, the sprayable aerosol adhesive as well as sprayable aerosol adhesive system more environmentally friendly. Additionally, most of the adhesives described in the prior art (WO2022098844, WO2017052373) relate to a filler containing sealant but with the drawback of drastically increasing the viscosity which would make them either not suitable for a sprayable adhesive or the sprayable adhesive composition is unstable such that a system cannot be used properly. As example a cannister would clog over time or the fillers cannot be re-dispersed easily. Further, the sprayable aerosol adhesive of the present invention differentiates from the known contact adhesives, not only because of the absence of solvents, but also due to the possibility of modifying the bulk adhesive formulation by adding a high amount of fillers; as such better adhesive properties like for example tensile strength and adhesion can be reached. Hence the second substrate is optionally coated and not mandatory as is frequently needed with commercial contact adhesives. Furthermore, the present invention differentiates from the state of the art contact adhesives in the reaction mechanism to bond different substrates. Contact adhesives are generally known by interacting with a substrate via physical bonding while in the present invention the interaction mainly happens via chemical bonding. The sprayable aerosol adhesive according to the invention, upon spraying onto a substrate, will also have a reduced waiting time before the second substrate can be applied compared to contact adhesives. For contact adhesives, the solvent must evaporate before the second substrate can be applied, while for the present invention only 30 seconds to 1 minute must be waited in order to evaporate the propellant.

[0026] DESCRIPTION OF EMBODIMENTS

[0027] For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combination of all or some of the features described.

[0028] Terminology used for describing particular embodiments is not intended to limit the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "and / or" includes any and all combinations of one or more of the associated listed items. It will be understood that the terms "comprises" and / or "comprising" specify the presence of stated features but do not preclude the presence or addition of one or more other features. It will be further understood that when a particular step of a method is referred to as subsequent to another step, it can directly follow said other step or one or more intermediate steps may be carried out before carrying out the particular step, unless specified otherwise. Likewise it will be understood that when a connection between structures or components is described, this connection may be established directly or through intermediate structures or components unless specified otherwise.

[0029] As used herein, the term “bulk adhesive formulation”, refers to any formulation having adhesive properties to bond a first substrate to a second substrate. The term “bulk adhesive formulation” can refer to either a liquid, wet or dry form.

[0030] As used herein, the term “sprayable aerosol adhesive”, refers to any formulation comprising the bulk adhesive formulation and a propellant. As used herein, the term “sprayable aerosol adhesive system”, refers to a system comprising the sprayable aerosol adhesive and a means to store and properly apply the aerosol adhesive in spray form.

[0031] As used herein, the term “silyl modified polyether compounds” refers to silyl modified polymer compounds having at least one polyether segment (or in other words at least one polyether structure).

[0032] As used herein the term “silyl modified polymer compounds comprising a silyl modified polyether backbone” refers to silyl modified polymer compounds having a backbone comprising at least one polyether segment (or in other words at least one polyether structure).

[0033] As used herein, the term “viscosity”, refers to a measure of a fluid’s resistance to flow and hence describing the internal friction of a moving fluid. Viscosity measurements are described in multiple handbooks or standards, such as ISO 3219-2. The viscosity of the bulk adhesive formulation of the invention are measured according to standard ISO 3219-2 in a plate - plate configuration at 200 micron gap using a SmartPave 102 dynamic shear rheometer. The viscosity values indicated for the bulk adhesive formulation are viscosity values measured after 24 hours, at a shear rate of 10 s_1and at room temperature. The viscosity of the silyl modified polymer compounds are measured via known standards such as Brookfield type B or DIN 51562. The viscosity of the commercial available silyl modified polymer compounds are as indicated on the product data sheet provided by the supplier.

[0034] As used herein the term “room temperature” refers to temperatures of about 20°C, this means referring to temperatures in the range 18° C to 25°C. Such temperatures will include, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C and 25°C. Room temperature may also refer to ambient temperature, however always within temperatures in the range 18° C to 25°C. As used herein, the term “non -re active”, refers to a compound that e.g. is mixed into the bulk adhesive formulation that does not react with any of the compounds present in said the bulk adhesive formulation.

[0035] As used herein, the term “initial tack”, or “tack value”, refers to the property of an adhesive allowing it to form a bond (i.e. to stick) immediately after the adhesive and the substrate are brought into contact (under low pressure) (typically between 0.1 to 10 seconds thereafter). The initial tack of an adhesive defines the ability of the adhesive to hold materials in place while the adhesive cures. A higher tack indicates a stronger immediate adhesion. The initial tack of an adhesive can be measured by means of a rheometer and is expressed in MPa or N / cm2.

[0036] As used herein, the term “permanent adhesive”, or “permanent bond”, refers to the property of an adhesive to stick firmly after a longer period of contact between the adhesive and the substrate. The strength of the bond can be characterized by the tensile lab shear strength, which can be measured by means of a tensile testing machine and is expressed in MPa or N / cm2. Generally, a bond is considered permanent when reaching a value of at least 50 N / cm2.

[0037] As used herein, the term “density”, refers to a compounds mass per unit of volume. Herein the term “density” is measured according to ISO 2811-1 unless otherwise specified.

[0038] As used herein, the term “wt %”, or “weight percentage”, or “percentage by weight”, refers to the mass fraction of a compound in a mixture divided by the total mass of said mixture, expressed as a percentage between 0 and 100.

[0039] As used herein, the term “weight ratio” as used in the sprayable aerosol adhesive refers to the amount of bulk adhesive formulation versus the amount of propellant used in the sprayable aerosol adhesive. The weight ratio is expressed in a form X:Y wherein X represents the weight amount of the bulk adhesive formulation and Y represents the weight amount of the propellant.

[0040] As used herein, the term “cannister”, refers to a means suitable for storing and / or spraying the bulk adhesive. Examples are a can, a tube but are not limited thereto.

[0041] As used herein, the term “filling a system”, refers to a means to fill a canister with the bulk adhesive formulation. Filling a canister, can for example, be done manually or mechanically.

[0042] As used herein, the term “non -re active”, refers to a compound that is mixed into the bulk adhesive formulation or the sprayable aerosol adhesive that does not react with any of the compounds present in said bulk adhesive formulation or said sprayable aerosol adhesive.

[0043] As used herein, the term “settling”, refers to the separation of any compound, for example a filler or a diluent, from the bulk adhesive formulation or the sprayable aerosol adhesive. There are two possibilities. Or one or more compounds with a higher density compared to the overall formulation migrate to the bottom or one or more materials with a lower density compared to the overall formulation migrate to the top. In either way this results in an inhomogeneous mixture. The settling can occur in different extents. Formulations showing none to limited settling are denoted as limited, formulations that show some settling overtime are denoted as moderate and formulations showing almost complete settling are denoted as severe. Formulations showing moderate to complete settling are not according to the invention.

[0044] The invention is based on a bulk adhesive formulation having a viscosity between 0.1 Pa.s - 8 Pa.s, preferably between 1 Pa.s - 7 Pa.s, more preferably between 1.5 Pa.s - 6 Pa.s which makes its suitable for sprayable application, more in particular for making a sprayable aerosol adhesive. The bulk adhesive formulation of the present invention comprises at least one low viscosity silyl modified polymer compound, at least one adhesion promoter and at least one dehydrating agent and further comprising, optionally at least one filler, optionally at least one reactive diluent and optionally at least one plasticizer compound. 80 to 100 wt% of all silyl modified polymer compounds in the formulation have a viscosity between 0.2 Pa.s and 8 Pa.s, preferably between 0.4 Pa.s and 5 Pa.s. Furthermore, in obtaining a bulk adhesive formulation with a viscosity between 0.1 Pa.s and 8 Pa.s, preferably between 1 Pa.s and 7 Pa.s, most preferably between 1.5 Pa.s and 6 Pa.s.

[0045] The bulk adhesive formulation of the present invention comprises, based on the total weight of the bulk adhesive formulation: a) 10-80 wt %, preferably 10-65 wt %, more preferably 10-40 wt %, most preferably 15-35 wt % of silyl modified polymer compounds; b) 0.5-5 wt %, preferably 0.8-3.5 wt % of at least one adhesion promoter; c) 0.5-5 wt %, preferably 0.8-3.5 wt % of at least one dehydrating agent; d) optionally 0-30 wt %, preferably 5-25 wt % of at least one plasticizer compound; e) optionally 0-60 wt% preferably 15-55 wt% and more preferably 30-50 wt% of at least one filler, f) optionally 0-20 wt%, preferably 1-15 wt% and even more preferably 2-10 wt% of at least one non-reactive diluent wherein the bulk adhesive formulation comprises 2-10 wt% of at least one non-reactive diluent in case the bulk adhesive formulation comprises > 15 wt% of at least one filler, and wherein at least 50 wt% of the silyl modified polymer compounds are silyl modified polyether compounds based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation.

[0046] The silyl modified polymer according to the invention are comprising a silyl modified backbone such as a silyl modified polyurethane, a silyl modified polyether, a silyl modified acrylic, or a combination thereof provided that at least 50 wt% of the silyl modified polymer compounds comprise a silyl modified polyether backbone based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation.

[0047] The silyl modified polymers may comprise silyl modified polyurethane compounds, silyl modified polyether compounds, silyl modified acrylic polymer compounds, or a combination thereof, provided that at least 50 wt% of the silyl modified polymer compounds are silyl modified polyether compounds based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation.

[0048] According to preferred embodiments, the silyl modified polymers comprise silyl modified polyether compounds and silyl modified acrylic polymer compounds, provided that the silyl modified polymers comprise at least 50 wt%, more preferably at least 75 wt%, most preferably at least 90 wt% silyl modified polyether compounds based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation.

[0049] According to preferred embodiments, the silyl modified polymers are selected from silyl modified polyether compounds.

[0050] The silyl modified polymer compound for use in the bulk adhesive composition refers to an oligomer comprising at least one reactive silyl group, preferably an alkoxysilyl group. Preferably, the oligomer comprises at least one alkoxysilyl group at end(s) of the molecule chain, and comprises at least one alkoxysilyl group bonded via the silicon atom at a terminal of the molecule; the two terminals of the molecule chain may be alkoxysilyl groups. Otherwise, the alkoxysilyl group may be present at one terminal and another functional group may appear on the other terminal, such as a (meth)acrylate, an ester, or an ahphatic hydrocarb yl group, etc.

[0051] The terminals of the silyl modified polymer compound preferably have the general formula of:-Ri-X-R2-SiR3a(OR4)3-a wherein Ri is the polymer backbone of the compound. The preferred backbone of the silyl terminated prepolymer is a polyether , a polyacrylate or a polyurethane provided that at least 50 wt% of the silyl modified polymer compounds comprise a silyl modified polyether backbone based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation. The backbone can have other functional groups, such as a (meth)acrylate, an ester, or an ahphatic hydrocarbyl group, etc. X is the linkage group. The alkoxysilyl groups are linked to the oligomer backbone by a functional group which can be but is not limited to a polyurethane group or a carbamate group; R2 is an aliphatic section connecting the linkage group X and the alkoxysilyl group. The most commercial silyl terminated prepolymers have two types of R2, namely: a-silyl-terminated prepolymers (R2 is -(CH2)-) and y-silyl-terminated prepolymers (R2 is -(CH2)s-); R3 is an alkyl, preferably methyl, ethyl, n-propyl, iso-propyl, and n-butyl, particularly preferred are methyl, and ethyl; R4 is an alkyl, preferably methyl, ethyl, n-propyl, isopropyl, and n-butyl, particularly preferred are methyl, and ethyl; a is an integer from 1 to 3, preferably from 2 to 3, more preferably 2.

[0052] In said bulk adhesive formulation, 80-100 wt %, preferably between 90-100 wt %, of the silyl modified polymer compounds have a viscosity between 0.2 Pa.s and 8 Pa.s, preferably between 0.4 Pa.s and 8 Pa.s, more preferably between 0.4 Pa.s and 5 Pa.s. Commercial examples of silyl modified polymer compounds having a viscosity below 8 Pa.s include, but are not limited to, comprise Polymer ST-grades of Evonik, SAX grades from Kaneka, Si-polyU grades from PolyU, geniosil® STP or Silres® grades from Wacker or SPUR+ grades from Momentive. Preferred silyl modified polymer compounds with a viscosity below 8 Pa.s for use in the present invention comprise ST XP1597, ST XP1598, S203H, SAX 260, SAX350, SAX530, SAX590, SAX730, Silres® BS6920, Silres® BS6921, Geniosil® XT 55, SPUR+ 3030 prepolymer. The remaining 0-20 wt %, preferably 0-10 wt % can include silyl modified polymer compounds with a viscosity above 8 Pa.s. Commercial examples of silyl modified polymer compounds having a viscosity above 8 Pa.s include, but are not limited to, Polymer ST-grades of Evonik, SAX or MA grades from Kaneka, Si-polyU grades from PolyU, Geniosil® STP or Silres® grades from Wacker or SPUR+ grades from Momentive. Preferred silyl modified polymer compounds with a viscosity above 8 Pa.s comprise ST XP 1599, MA452, MAX923, S303H, S227, S327, SAX400, SAX750, SAX 575, SAX510, SAX580, Geniosil® STP-E10, Geniosil® STP -E 15, Geniosil® STP-E 30, Geniosil® STP-E35, Si-PolyU 5013, SPUR+ 3040 prepolymer, SPUR+ 1050 prepolymer, SPUR+ 1060 prepolymer, SPUR+ 1015 prepolymer, SPUR+ 1020 prepolymer.

[0053] The bulk adhesive formulation comprises adhesion promoters to increase the performance of the bulk adhesive formulation towards the substrates to be bonded. The at least one adhesion promoter can be any adhesion promoter described to date for that purpose and which is preferably compatible with the bulk adhesive formulation. Preferred adhesion promoters comprise aminosilanes, epoxy silanes, ureido silanes, acryl silanes, alkyl silanes, sulfur silanes, vinyl silanes, chloro silanes, (meth)acryloylsilanes, anhydridosilanes, carbamatosilanes, iminosilanes, oligomeric forms of these silanes, adducts formed from primary aminosilanes with epoxysilanes or (meth) acryloylsilanes or anhydridosilanes, amino-functional alkylsilsesquioxanes or a combination thereof. Preferably the adhesion promoter is an aminosilane.

[0054] Suitable aminosilane adhesion promoters include 3- aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, aminomethyltrimethoxysilane, aminomethyltriethoxysilane, 3- aminopropylmethyldiethoxysilane, (N-2-aminoethyl)-3- aminopropyltrimethoxysilane, (N-2-aminoethyl)-3- aminopropyltriethoxysilane, diethylenetriaminopropyltrimethoxysilane, phenylaminomethyl-trimethoxysilane, (N-2-aminoethyl)-3- aminopropylmethyldimethoxysilane, 3-(N- phenylamino)propyltrimethoxysilane, 3- piperazinylpropylmethyldimethoxysilane, 3-(N,N- (hmethylaminopropyl)aminopropyhnethyldimethoxysilane, tri[(3- triethoxysilyl)propyl] amine, tri[(3-trimethoxysilyl)propyl] amine, and the oligomers thereof, 3-(N,N-dimethylamino)propyltrimethoxysilane, 3-(N,N- dimethylamino)-propyltriethoxy silane, (N,N - dimethylamino)methyltrimethoxysilane, (N,N- dimethylamino)methyltriethoxysilane, bis(3-trimethoxysilyl)propylamine, bis(3-triethoxysilyl)propylamine, and combinations thereof.

[0055] Suitable epoxy silane adhesion promoters include 3- Glycidoxypropyltrimethoxysilane, 3-Glycidoxypropyltriethoxysilane, 3- Glycidoxypropylmethyldiethoxysilane, 2-(3,4- ep oxy cyclohexyl) ethyltrim ethoxy silane .

[0056] Suitable ureido silane adhesion promoters include 3- Ureidopropyltrimethoxysilane, 3-Ureidopropyltriethoxysilane.

[0057] Suitable acryl silanes adhesion promoters include 3- Methacryloxypropyltrimethoxysilane, 3- Methacryloxypropylmethyldimethoxysilane.

[0058] Suitable alkyl silanes adhesion promoters include Methyltrimethoxysilane, Methyltris-(methylethylketoxime)silane, n- octyltriethoxysilane, n-octyltrimethoxysilane, n-Propyltrimethoxysilane, Phenyltrimethoxysilane.

[0059] Suitable chloro silane adhesion promoters include 3-

[0060] Chloropropyltrimethoxysilane, 3-Chloropropyltriethoxysilane. Suitable sulfur silanes adhesion promoters include 3- Mercaptopropyltrimethoxysilane, 3-Mercaptopropylmethyldimethoxysilane, 3-Thiocyanatopropyltriethoxysilane.

[0061] Suitable vinyl silane adhesion promoters include Vinyltriethoxysilane, Vinyltris-(2-methoxyethoxy)silane , Vinyltrimethoxysilane, Vinyltriacetoxysilane, Vinyltris- (methylethylketoxime)silane.

[0062] Preferably the adhesion promoters are aminosilanes selected from the group of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, aminomethyltrimethoxysilane, aminomethyltriethoxysilane, 3-(N,N- dimethylamino)propyltrimethoxysilane, 3-(N,N- dimethylamino)propyltriethoxysilane, (N,N - dimethylamino)methyltrimethoxysilane, (N,N- dimethylamino)methyltriethoxysilane, bis(3-trimethoxysilyl)propylamine, bis(3-triethoxysilyl)propylamine or combinations thereof.

[0063] The bulk adhesive formulation comprises at least one dehydrating agents to obtain a more stable composition. Any dehydrating agent described to date for that purpose that is preferably compatible with the bulk adhesive formulation can be used.

[0064] Suitable dehydrating agents include vinyl trialkoxysilanes, tetraethoxysilanes, organoalkoxysilanes having a functional group in the a position to the silane group, especially N- (methyl dimeth oxy silylmethyl) -O- methylcarbamate, (methacryloyloxymethyl)silanes, methoxymethylsilanes, orthoformic esters, more preferably vinyltrimethoxysilane, vinyltriethoxysilane or poly tetramethylene oxide, most preferably vinyltrimethoxysilane.

[0065] The adhesive formulation of the present invention may further comprise at least one plasticizer compound to reduce the viscosity and to facilitate spraying of the bulk adhesive formulation. The plasticizer compound can be any compound described to date for that purpose that is preferably compatible with the bulk adhesive formulation.

[0066] The plasticizer may be any of the plasticizers commonly used in compositions based on silane-functional polymers. These include, for example, carboxylic esters such as phthalates, especially dioctyl phthalate, bis(2 -ethylhexyl) phthalate, bis(3-propylheptyl) phthalate, diisononyl phthalate or diisodecyl phthalate, diesters of ortho-cyclohexane-dicarboxylic acid, especially diisononyl 1 ,2-cyclohexanedicarboxylate, adipates, especially dioctyl adipate, bis(2- ethylhexyl) adipate, azelates, especially bis(2 -ethylhexyl) azelate, sebacates, especially bis(2 -ethylhexyl) sebacate or diisononyl sebacate, glycol ethers, glycol esters, organic phosphoric or sulfonic esters, sulfonamides, polybutenes, or fatty acid methyl or ethyl esters derived from natural fats or oils, also called “biodiesel”.

[0067] Furthermore suitable are polymeric plasticizers. These have the advantage of lower migration tendency into surrounding areas and lower contribution to VOC levels. The term “polymeric plasticizer” herein means a polymeric additive that is liquid at room temperature and contains no hydrolyzable silane groups. In contrast to traditional plasticizers, such as phthalates, the polymeric plasticizers generally have a higher molecular weight. Suitable polymeric plasticizers include polyols, as long as they are liquid at room temperature. Preferred polyols suitable as polymeric plasticizers include polyether polyols, polyester polyols, polyhydrocarbon polyols, polybutadiene polyols, and poly(meth)acrylate polyols.

[0068] Preferably the plasticizer compounds are selected from diisononyl- 1,2-cyclohexaandicarboxylaat (DINCH), diisononyl phthalate (DINP), a polyol, a polyether polyol, an alkylsulphonic phenyl ester, a polyethylene glycol, or a combination thereof. Some of the silyl modified polymers in the bulk adhesive formulation have a lower functionality and are acting as reactive diluent to lower the viscosity of the bulk adhesive formulation. Said compounds are incorporated in the polymer network of the bulk adhesive formulation that is formed upon curing and are optionally added to the bulk adhesive formulation. Said compounds are also referred to as reactive diluent compounds. Preferably said reactive diluent compounds are compatible with the bulk adhesive formulation and are selected from monofunctional silyl modified polymers. Most preferably said monofunctional silyl modified polymers are selected from monofunctional silyl modified polyethers.

[0069] In case monofunctional silyl modified polyethers are used as reactive diluent compounds they form part of all silyl modified polymer (polyether) compounds present in the bulk adhesive formulation. The amount of such monofunctional silyl modified polymer (polyether) reactive diluent is generally 0 to 40 wt%, preferably 10 to 35 wt%, based on bulk adhesive formulation. Commercial examples of suitable reactive diluents include SATO 10, SAXO 15, SAT115, SAT145, geniosil® XM25 and geniosil® XM20 from Kaneka or Wacker.

[0070] According to preferred embodiments, the bulk adhesive formulation may further comprise at least one filler and at least one non- reactive diluent. The at least one filler is introduced based on its physical properties such as density. The at least one filler is provided to modify the rheological as well as the technical properties of the bulk adhesive formulation. The at least one filler preferably has a density between 0.1-6 g / cm3, more preferably between 0.3-5 g / cm3, even more preferably between 0.4-4 g / cm3, most preferably between 0.5-3 g / cm3.

[0071] Additionally, the at least one non-reactive diluent may (optionally) be added to further reduce the viscosity when needed. According to the invention, the bulk adhesive formulation may comprise, based on the total weight of the bulk adhesive formulation: a) 0-60 wt %, preferably 15-55 wt %, more preferably 30-50 wt % of at least one filler; b) 0-20 wt %, preferably 1-15 wt %, more preferably 2-10 wt % of at least one non-reactive diluent.

[0072] The at least one filler can be any filler, described to date, that is preferably compatible with the bulk adhesive formulation and / or that can be easily re-dispersed such as by manual shaking of a cannister.

[0073] Suitable fillers include inorganic or organic fillers such as grounded or participated calcium carbonate optionally coated with fatty acids, stearic acid, baryte (heavy spar), talcs, quartz flours, quartz sand, dolomites, wollastonites, kaolins, calcined kaolins, mica (potassium aluminum silicate), molecular sieves, aluminum oxides, aluminum hydroxides, magnesium hydroxide, silicas including finely divided silicas from pyrolysis processes, industrially produced carbon blacks, graphite, metal powders such as aluminum, copper, iron, silver or steel, PVC powder or hollow spheres, titanium dioxide, glass bubbles, perlite, expanded thermoplastic microspheres, silicate ceramic microspheres, vermiculite platelets, or any combination thereof. Commercial examples of calcium carbonate include Hakuenka® CCR, hakuenka® CCR S10, imercarb® 20S, imerseal® 36S, imerseal® 50s, imerseal® 96S, omyabond® 520, omyacarb® 2t, polycarb® 88s or any combination thereof. Commercial examples of glass bubbles include 3M glass bubbles KI, 3M glass bubbles K25, 3M glass bubbles K32, Poraver® 0.04 - 0.125, or any combination thereof. Other commercially available fillers include Dicalite® GPE-18, Expancel® 920 DE 40 d30, Expancel® 920 DE 40 d25, sumfoam® KU powder P300, fillite® 160, microlite® FPSV, or any combination thereof. Preferably the fillers are selected from grounded or participated calcium carbonate, silicas or titanium dioxide. The at least one non-reactive diluent can be any non-reactive diluent described to date that is preferably compatible with the bulk adhesive formulation.

[0074] Suitable non-reactive diluents preferably include an ether or acetal structure, more preferably the non-reactive ether structured diluent is selected from the group consisting of (Ethoxymethoxy)ethane, 1- (Propoxymethoxy)propane, l-(Butoxymethoxy)butane , 2,5,7,10- Tetraoxaundecane, 3-({[(2-Ethylhexyl)oxy]methoxy}methyl)heptane, 4,8- Dimethyl-2,5,7,10-tetraoxaundecane, 1,3-Dioxolane, ethylene glycol methyl butyl ether, ethylene glycol ethyl butyl ether, ethylene glycol dibutyl ether, diethoxypropane, diethyoxybutane, ethoxymethoxypropane, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl ethyl ether, diethylene glycol dibutyl ether, triethylene glycol ethyl methyl ether, triethylene glycol diethyl ether, triethylene glycol butyl methyl ether, triethylene glycol butyl ethyl ether, tetraethylene glycol ethyl methyl ether, tetraethylene glycol butyl methyl ether, dipropylene glycol dimethyl ether and polypropylene glycol dimethyl ether having 3-5 propylene units, isomers of the foregoing and any combinations thereof, preferably selected from the group consisting of l-(Butoxymethoxy)butane , 2,5,7, 10-Tetraoxaundecane, 3-({[(2-Ethylhexyl)oxy]methoxy}methyl)heptane, 4,8-Dimethyl-2,5,7,10-tetraoxaundecane, 2-methoxy-l-(2- methoxypropoxy)propane, isomers of the foregoing or any combinations thereof.

[0075] The bulk adhesive formulation may further comprise additive compounds to further modify the adhesive properties and / or appearance of the bulk adhesive formulation according to the need of the sprayable application. Additive compounds generally comprise, based on the total weight of the bulk adhesive formulation, 0-50 wt %, preferably 0-30 wt %, more preferably 0-15 wt % in the bulk adhesive formulation. Examples of additive compounds include a pigment or dye (to address the color), a rheology control agent (to influence to flow behavior), a stabilizer (to stabilize against oxidation, heat, light or UV radiation), a catalyst (to facilitate the adhesive network formation, crosslinking), a tackifier, a flame retardant, a surface-active substance, a biocide or a combination thereof.

[0076] Suitable pigments include any pigment known to date that is preferably compatible with the bulk adhesive formulation such as titanium dioxide or carbon black.

[0077] Suitable dyes include any dye known to date that is preferably compatible with the bulk adhesive formulation.

[0078] Suitable rheology control agents include a thickener, a thixotropy agent, a fumed silica, an amide waxe, an organic rheological additive, a sheet silicate such as a bentonite, a derivative of castor oil, a hydrogenated castor oil, a polyamide, a polyurethane, an urea compound, a cellulose ether, a hydrophobically modified polyoxyethylene, or any combination thereof.

[0079] Suitable stabilizers include stabilizers described to date that are compatible with the bulk adhesive formulation such as hindered amine light stabilizers (HALS), UV stabilizers and antioxidants. Commercial examples include irganox® 1135, tinuvin® 571, tinuvin® 765, geniosil® stab F, irganox® 1010, irganox® 245, tinuvin® 326, tinuvin® 5151, tinuvin® 770, addworks® IBC 760, eversorb® HP5, tinuvin® 312, eversorb® Hl, eversorb® HP3, eversorb® HP4, hostavin® N30P.

[0080] Suitable catalysts include metalorganic compounds, basic nitrogen or phosphorus compounds. Suitable metalorganic compounds comprise compounds of tin, titanium, zirconium, aluminum or zinc. Preferably said metalorganic catalyst comprises an organotin compound, an inorganic tin salt or tin compound derivatives. Preferably the tin compound in said catalyst is bivalent or tetravalent. Examples of inorganic tin salts include tin(H) chloride, tin(IV) chloride, or any combination thereof. Examples of organotin compounds include tin organyles, the 1,3-dicarbonyl compounds of bivalent or tetravalent tin, for example, the acetylacetonates such as (h(n-butyl)tin(IV) di(acetylacetonate), di(n-octyl)tin(IV) di(acetylacetonate), (n-octyl)(n-butyl)tin(IV) di(acetylacetonate); the dialkyl tin(IV) dicarboxylates, for example, di-n-butyltin dilaurate, di-n-butyltin maleate, di-n-butyltin diacetate, di-n-octyltin dilaurate, di-n-octyltin diacetate, or the corresponding dialkoxylates, for example, di-n-butyltin dimethoxide; oxides of tetravalent tin, for example, dialkyltin oxides, such as, for example, di-n-butyltin oxide and di-n-octyltin oxide; and the tin(II) carboxylates such as tin(II) octoate or tin(II) phenolate. Examples of tin compound derivatives include tin compounds of ethyl silicate, dimethyl maleate, diethyl maleate, dioctyl maleate, dimethyl phthalate, diethyl phthalate, dioctyl phthalate, such as, for example, di(n-butyl)tin(IV) di(methyl maleate), di(n-butyl)tin(IV) di(butyl maleate), di(n-octyl)tin(IV) di(methyl maleate), di(n-octyl)tin(IV) di(butyl maleate), di(n-octyl)tin(IV) di(isooctyl maleate); and di(n-butyl)tin(IV) sulfide, (n-butyl)2-Sn(SCH2 COO), (n-octyl)2-Sn(SCH2COO), (n-octyl)2-Sn(SCH2CH2COO), (n-octyl)2- Sn(SCH2CH2COOCH2CH2OCOCH2S), (n-butyl)2-Sn(SCH2COO-i-C8Hi7)2 , (n-octyl)2-Sn(SCH2 COO-i-CsHi?^ , and (n-octyl)2-Sn(SCH2COO-n-C8Hi7)2. Preferably the tin compound is selected of 1,3-dicarbonyl compounds of bivalent or tetravalent tin, the dialkyltin(IV) dicarboxylates, the dialkyltin(IV) dialkoxylates, the dialkyltin(IV) oxides, the tin(II) carboxylates, or any combination thereof. More preferably the tin compound is a dialkyltin(IV) dicarboxylate, most preferably di-n-butyltin dilaurate or di-n-octyltin dilaurate.

[0081] Nitrogen-containing compounds suitable as catalysts are in particular amines, especially N-ethyl-diisopropylamine, N,N,N’,N’- tetramethylalkylenediamines, 1 ,4-diazabicyclo[2.2.2]octane; amidines such as especially 1 ,8- diazabicyclo[5.4.0]undec-7-ene (DBU), 1 ,5- diazabicyclo[4.3.0]non-5-ene (DBN), 6-dibutylaminol,8-diazabicyclo- [5.4.0]undec-7-ene; guanidines such as especially tetramethylguanidine, 2- guanidino-benzimidazole, acetylacetone- guanidine, 3-di-o-tolyl-guanidine, 2-tert-butyl-l,l,3,3-tetramethyl guanidine; and imidazoles, in particular N- (3-trimethoxysilylpropyl)-4,5-dihydroimidazole and N-(3- triethoxysilylpropyl)-4,5-dihydroimidazole. Preferred nitrogen or phosphorus containing catalyst compounds are especially imidazoles, pyridines, phosphazene bases, secondary or tertiary amines, hexahydrotriazines, biguanides, guanidines, or amidines.

[0082] Alternatively, the bulk adhesive formulation solely comprises a highly reactive silyl modified polymer such that the use of a catalyst would be obsolete as the network will purely be formed by the highly reactive silyl modified polymer.

[0083] Suitable tackifiers are known in the art of adhesives and are used to increase to improve tack and stickiness. Suitable tackifiers may include a natural resin (resins, produced from plant or hydrocarbon sources), fat or oil, or a non-reactive polymer (which is preferably solid at room temperature) or any combination thereof.

[0084] A tackifier according to the invention can be of the following types: Terpene Phenolic, Polyterpene Resin, Alpha Methyl Styrene (AMS) Phenolic Resin, Alpha Methyl Styrene Resin, Rosin Ester, Glycerol Ester of hydrogenated Rosin, Pentaerythritol ester of gum Rosin, polybutene. Commercial examples of tackifiers are: Dertophene® T, Dertophene® T105, Dertophene® H150 and Dertophene® 1510, Dercolyte® Al 15, Dercolyte® TS105, Hydrogral® G and Granolite® P from DRT; Sylvares TP115, Sylvares® TP300, Sylvares® TO7042, Sylvares® TR A25L, Sylvares® 520, Sylvares® SA85, Sylvatec® RE 12, Sylvalite® RE100L from KRATON; Polybut 30 and Polybut 150 from Kemat.

[0085] Suitable flame retardants are known in the art of adhesives and may include aluminum hydroxide and / or magnesium hydroxide, or organic phosphoric esters such as triethyl phosphate, tricresyl phosphate, triphenyl phosphate, diphenyl cresyl phosphate, isodecyl diphenyl phosphate, tris(l,3- dichloro-2 -propyl) phosphate, tris(2 -chloroethyl) phosphate, tris(2- ethylhexyl) phosphate, tris(chloroisopropyl) phosphate, tris(chloropropyl) phosphate, isopropylated triphenyl phosphate, mono-, bis- or tris(isopropylphenyl) phosphates of different degrees of isopropylation, resorcinol bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate) or ammonium polyphosphates.

[0086] Suitable surface -active substances include a wetting agent, a levelling agent, a de-aerating agent, a defoamer or any combination thereof.

[0087] Suitable biocide include an algicide, a fungicide or a substance that inhibits fungal growth, or a combination thereof and / or other substances customarily used in curable compositions.

[0088] Further the bulk adhesive formulation can be combined with a propellant to obtain a sprayable aerosol adhesive. Said sprayable aerosol adhesive is suitable for covering a substrate with an adhesive upon release from the aerosol.

[0089] Suitable propellants include dimethyl ether, butane, propane, isobutane, hydrofluorocarbon (HFC), hydrofluoro-olefins (HFO), dry air, nitrogen or any combinations thereof provided that the propellant comprises at least 70 wt %, preferably at least 80 wt %, more preferably at least 90 wt % of a dimethyl ether based on the total weight of the propellant and optionally comprising up to 30 wt % of butane, propane, isobutane, hydrofluorocarbon (HFC), hydrofluoro-olefins (HFO), dry air, nitrogen or any combinations thereof.

[0090] The weight ratio of bulk adhesive formulation and propellant in said sprayable aerosol adhesive being defined as the weight of the bulk adhesive formulation over the weight of the propellant, is between 40:60 to 90:10, preferably 55:45 to 85:15, more preferably between 70:30 to 80:20. The sprayable aerosol adhesive generally has a density of between 0.5 to 1.8 g / cm3, preferably between 0.6 to 1.5 g / cm3, more preferably between 0.8 to 1.3 g / cm3.

[0091] Furthermore, according to the invention the spray able aerosol adhesive can be combined with a system to create a sprayable aerosol adhesive system. Preferably, the system comprises a cannister, an aerosol spray can or an inverted aerosol can.

[0092] Additionally, according to the invention, a use of the sprayable adhesive system is provided. The use comprising at least the steps of: a) spraying the sprayable aerosol adhesive according to the invention on at least a first surface of a first substrate to achieve a coated first substrate; b) providing a second substrate; c) optionally spraying the sprayable aerosol adhesive according to the invention on at least one surface of the second substrate to achieve a coated second substrate; d) applying the second substrate which is optionally coated on said coated first substrate.

[0093] The sprayable adhesive generally obtains within 5 minutes after spraying, a tack value between 0.02 N / cm2and 5 N / cm2, more preferably between 0.1 N / cm2and 3.5 N / cm2, even more preferably between 0.1 N / cm2and 1 N / cm2and generally reaches a permanent bond within 15 to 1500 minutes, preferably between 30 and 500 minutes, more preferably between 45 and 250 minutes after spraying the spray able adhesive onto a first substrate and application of the second substrate. The absence of solvents and hence no need to evaporate the solvent combined with the tack values as described above would allow a fast application of a second substrate onto the first substrate while allowing repositioning and correction of small misalignments during an application. For state of the art contact adhesives the initial tack (after evaporation of the solvent) is much higher compared to the tack value of the sprayable aerosol adhesive according to the invention, resulting in the incapability of repositioning the substrates after being bonded.

[0094] Preferably, the sprayable aerosol adhesives has a tack value of between 4 N / cm2and 12 N / cm2within 10 to 90 minutes after spraying while reaching a permanent bond within 15 to 1500 minutes, preferably within 30 to 500 minutes, more preferably between 45 and 250 minutes after spraying.

[0095] Further, a method of making the spray able adhesive system is provided. The method comprising at least the following steps: a) mixing at least one silyl modified polymer, at least one dehydrating agent, at least one adhesion promoter, optionally at least one reactive diluent, optionally at least one plasticizer compound, optionally at least one filler and optionally further additives, b) optionally further adding a non-reactive diluent to further reduce the viscosity to form a bulk adhesive formulation having a viscosity in the range of 0.1 Pa.s to 8 Pa.s, preferably 1 Pa.s to 7 Pa.s, more preferably 1.5 Pa.s to 6 Pa.s, c) filling the system with the bulk adhesive formulation obtained in foregoing steps, d) adding at least one propellant wherein the propellant comprises at least 70 wt%, preferably at least 80 wt%, more preferably at least 90 wt% of a dimethyl ether and optionally further comprising up to 30 wt% of butane, propane, isobutane, hydrofluorocarbon (HFC), hydrofluoro- oleofins (HFO), dry air, nitrogen or a combination thereof to the filled system to form a sprayable aerosol adhesive having a density between 0.8-1.3 g / cm3.

[0096] Preferably the mixing in step a. is done with a butterfly blade or a dissolving bar and / or one or more dispersing blades at mixing speeds between 100 and 2000 rpm.

[0097] Examples

[0098] Material and Methods

[0099] In the following examples, bulk adhesive formulations and sprayable aerosol adhesives were prepared following the procedure described above. Different compounds (in wt %) for the bulk adhesive formulation are listed in Table 1. The obtained spray able aerosol adhesive is applied via an sprayable aerosol adhesive system onto a substrate, the propellant immediately starts to evaporate upon spraying the substrate, resulting in a tackified (read tack value) substrate (see Table 2).

[0100] The method for measuring the tack value was performed by means of a tack test with a SmartPave 102 dynamic shear rheometer. The tests were performed with a spindle and a plate made of chemically resistant stainless steel (AISI 316L).

[0101] Long-term tack values were measured similar to the initial tack. With the sole difference being the waiting time after spraying a substrate with the sprayable aerosol adhesive. Long-term tack values were measured after 30 min, 45 min, 60 min or longer. All tested samples were stored in a conditioned room at 23°C and 50% relative humidity. Viscosity of the bulk adhesive formulation as well as the sprayed aerosol adhesive after spraying a substrate were measured according to ISO 3219-2 in a plate - plate configuration with a 200 pm gap. The viscosity was measured with a SmartPave 102 dynamic shear rheometer. The density of the bulk adhesive formulation was measured according to ISO 2811-1. Due to the high volatility of the propellant no density measurement could be performed on the sprayable aerosol adhesive; as such the density of the sprayable aerosol adhesive was calculated using the formula: Wherein paerosoi represents the calculated density of the sprayable aerosol adhesive, pbuik represents the measured density of the bulk adhesive formulation, ppropeiiant represents the density of the used propellant and mbuikrepresents the weight percentage of the bulk adhesive formulation based on the total weight of the sprayable aerosol adhesive.

[0102] Table 1: Composition of the bulk adhesive formulation (in wt %) and viscosity in Pa.s ( Comp 1-5 referring to comparative examples, Inv. 7, 9, 10, 14 and 15 referring to examples according to the invention).

[0103] Table 2: Tack value (N / cm2) and viscosity (Pa.s) measured in function of time for the sprayable aerosol adhesive (inventive example 14 with 20 wt% dimethylether as propellant based on the total weight of the sprayable adhesive). Table 3: Tack value (N / cm2) measured in function of time for state of the art adhesives.

[0104] Furthermore, the dispersion stability of the filler was tested. The stability of the fillers was tested by checking the severity of sedimentation over time. Compositions showing none to limited settling were denoted as limited, composition that show some settling over time were denoted as moderate and compositions showing almost complete settling were denoted as severe. Results have shown that fillers, preferably have a density in a range of 0.3-5 g / cm3, were less subjected to settling.

[0105] Lastly, the tack value of a sprayable aerosol adhesive according to the invention was evaluated over time as is shown in Table 2. Table 2 shows that an increase in tack value was observed over time. Table 2 further shows that a low tack value is measured immediately after applying the adhesive on a first substrate such that repositioning the second substrate is possible. After 45 to 60 minutes the tack value has increased enough so the second substrate stays in place when applied vertically onto the first substrates. Still slight adjustments are possible with these tack values. The tack value of a sprayable aerosol adhesive according to the invention can be compared with the tack values of other commercially available adhesive systems as shown in table 3. The tack value of a spray able aerosol adhesive according to the invention after 45 and 60 minutes compares to the tack values of commercially available adhesives based on silyl terminated polymers, which do not increase much within their open time. Also substrates bonded with these adhesives can be repositioned for a certain timeframe. For contact adhesives the tack after evaporation of the solvent is much higher compared to the tack value of a spray able aerosol adhesive according to the invention, resulting in the incapability of repositioning the substrates after being bonded.

[0106] For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. Of course, it is to be appreciated that any one of the above embodiments or processes may be combined with one or more other embodiments or processes to provide even further improvements in finding and matching designs and advantages.

Claims

CLAIMS1. A sprayable aerosol adhesive formulation, the spray able aerosol adhesive formulation comprising, based on the total weight of the sprayable aerosol adhesive formulation:1) A bulk adhesive formulation comprising: a) 10-80 wt%, preferably 10-65 wt%, more preferably 10-40 wt%, most preferably 15-35 wt% of silyl modified polymer compounds; b) 0.5-5 wt%, preferably 0.8-3.5 wt% of at least one adhesion promoter; c) 0.5-5 wt%, preferably 0.8-3.5 wt% of at least one dehydrating agent; d) optionally 0-30 wt%, preferably 5-25 wt% of at least one plasticizer compound; e) optionally 0-60 wt% preferably 15-55 wt% and more preferably 30-50 wt% of at least one filler, f) optionally 0-20 wt%, preferably 1-15 wt% and even more preferably 2-10 wt% of at least one non-reactive diluent, and2) A propellant comprising at least 70 wt% of a dimethyl ether propellant and optionally further comprising up to 30 wt% of butane, propane, isobutane, hydrofluorocarbon (HFC), hydrofluoro- oleofin (HFO),dry air, nitrogen or a combination based on the total weight of the propellant, and wherein based on the total weight of all silyl modified polymer compounds in the formulation, 80-100 wt%, preferably 90-100 wt% of the silyl modified polymer compounds have a viscosity in the range of0.2 Pa.s to 8 Pa.s, preferably in the range of 0.4 Pa.s to 8 Pa.s, more preferably between 0.4 Pa.s and 5 Pa.s, and wherein the bulk adhesive formulation has a viscosity in the range of 0.1 Pa.s to 8 Pa.s, preferably 1 Pa.s to 7 Pa.s, more preferably in the range of 1.5 Pa.s to 6 Pa.s (the viscosity measured according to ISO 3219-2 in a plate - plate configuration at 200 micron gap after 24 hours at a shear rate of 10 s1and at room temperature), and wherein the bulk adhesive formulation comprises 2-10 wt% of at least one non-reactive diluent in case the bulk adhesive formulation comprises > 15 wt% of at least one filler, and wherein at least 50 wt% of the silyl modified polymer compounds are silyl modified polyether compounds based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation, and wherein the weight ratio of the bulk adhesive formulation to propellant is between 40:60 to 90:10.

2. The spray able aerosol adhesive formulation according to claim 1, wherein the silyl modified polymer compounds are selected from a silyl modified polyether, a silyl modified acrylic polymer, or a combination thereof.

3. The spray able aerosol adhesive formulation according to claim 1, wherein the silyl modified polymer compounds comprise at least 75 wt%, more preferably at least 90 wt% silyl modified polyether compounds based on the total weight of all silyl modified polymer compounds in the bulk adhesive formulation, most preferred the silyl modified polymers are selected from silyl modified polyether compounds.

4. The sprayable aerosol adhesive formulation according to any of foregoing claims wherein the silyl modified polymer compounds optionally comprise 0 to 40 wt%, preferably 10 to 35 wt% monofunctional silyl modified polymer compounds, more preferably monofunctional silyl modified polyether compounds based on the total weight of the bulk adhesive formulation as reactive diluent compounds.

5. The spray able aerosol adhesive formulation according to any of foregoing claims wherein the filler has a density in the range of 0.1-6 g / cm3, preferably 0.3-5 g / cm3, more preferably 0.4-4 g / cm3and most preferably between 0.5-3 g / cm3(the density measured according to ISO 2811-1).

6. The spray able aerosol adhesive formulation according to any of foregoing claims, wherein the adhesion promoter is selected from the group consisting of an aminosilane, an epoxy silane, an ureido silane, an acryl silane, an alkyl silane, a chloro silane, a sulfur silane, a vinyl silane, or a combination thereof, preferably the adhesion promoter comprises an aminosilane.

7. The sprayable aerosol adhesive formulation according to any of claims 5-6, wherein the at least one non-reactive diluent comprises an ether or acetal structure, preferably the non-reactive diluent is selected from the group l-(Butoxymethoxy)butane , 2,5,7, 10-Tetraoxaundecane, 3-({[(2- Ethylhexyl)oxy]methoxy}methyl)heptane, 4,8-Dimethyl-2,5,7, 10- tetraoxaundecane, 2-methoxy-l-(2-methoxypropoxy)propane or combinations thereof.

8. The spray able aerosol adhesive formulation according to any of foregoing claims, wherein the at least one plasticizer compound is preferably selected from the group di-isononyl-l,2-cyclohexaandicarboxylaat (DINCH), diisononyl phthalate (DINP), a polyol, a polyether polyol, an alkylsulphonic phenyl ester, a polyethylene glycol, or a combination thereof.

9. The spray able aerosol adhesive formulation according to any of foregoing claims, further comprising, based on the total weight of the formulation, 0-50 wt% preferably 0-30 wt% and even more preferably 0-15 wt% additive compounds wherein the additive compounds are selected from a pigment, a dye a stabilizer, a catalyst, a rheology control agent, a tackifier, a flame retardant, a surface -active substance, a biocide or a combination thereof.

10. The sprayable aerosol adhesive formulation according to any of foregoing claims , wherein the propellant comprises preferably at least 80 wt%, more preferably at least 90 wt% of a dimethyl ether based on the total weight of the propellant.

11. The spray able aerosol adhesive formulation according to any of foregoing claims, wherein the weight ratio of the bulk adhesive formulation to propellant is preferably between 55:45 to 85:15, more preferably between 70:30 to 80:20.

12. The sprayable aerosol adhesive formulation according to any of foregoing claims wherein the density of the sprayable aerosol adhesive is between 0.8-1.3 g / cm3.

13. A spray able aerosol adhesive system comprising the spray able aerosol adhesive according to any of foregoing claims , said sprayable aerosol adhesive system preferably selected from a cannister, an inverted aerosol can or an aerosol spray can.

14. Use of the sprayable aerosol adhesive system according to claim 13, said use comprising at least the steps of: a) spraying the sprayable aerosol adhesive according to any of claims 1-12 on at least a first surface of a first substrate to achieve a coated first substrate;b) providing a second substrate; c) optionally spraying the sprayable aerosol adhesive according to any of claims 1-12 on at least one surface of the second substrate to achieve a coated second substrate; d) applying the second substrate which is optionally coated on said coated first substrate, and wherein the sprayed aerosol adhesive within 5 minutes after spraying, has a tack value between 0.02 N / cm2and 5 N / cm2, more preferably between 0.1 N / cm2and 3.5 N / cm2, and wherein a permanent bond is reached within 15 to 1500 minutes, preferably between 30 and 500 minutes and more preferably between 45 and 250 minutes after spraying the sprayable adhesive onto said first substrate .

15. Use of the sprayable aerosol adhesive system according to claim 13, wherein the sprayable aerosol adhesive has a tack value between 4 N / cm2and 12 N / cm2within 10 to 90 minutes and wherein a permanent bond is reached within 15 to 1500 minutes, preferably within 30 to 500 minutes, more preferably within 45 to 250 minutes.

16. A method of making a sprayable aerosol adhesive system according to claim 13, said method comprising at least following steps: a) mixing silyl modified polymers comprising at least one silyl modified polymer compound, at least one dehydrating agent, at least one adhesion promoter, optionally at least one plasticizer compound, optionally at least one filler and optionally additives, b) optionally further adding a non-reactive diluent to further reduce the viscosity to form a bulk adhesive formulation havinga viscosity in the range of 0.1 Pa.s to 8 Pa.s, preferably 1 Pa.s to 7 Pa.s, more preferably 1.5 Pa.s to 6 Pa.s, c) filling the sprayable aerosol adhesive system with the bulk adhesive formulation obtained in foregoing steps, d) adding at least one propellant wherein the propellant comprises at least 70 wt%, preferably at least 80 wt%, more preferably at least 90 wt% of a dimethyl ether based on the weight of all propellants and optionally further comprising up to 30 wt% of butane, propane, isobutane, hydrofluorocarbon (HFC), hydrofluoro-oleofin (HFO), dry air, nitrogen or a combination thereof to the filled system to form a sprayable aerosol adhesive having a density between 0.8- 1.3 g / cm3.

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