Two-component polyurethane adhesive with hydrophobic prepolymer for moisture protection

Abstract

Two-component polyurethane adhesive formulations having a hydrophobic polyol that provides improved moisture resistance.

Description

Background Technology

[0001] With the rapid development of electric vehicles, the battery industry has become increasingly important. One of the key requirements for high-energy-density battery modules is structural bonding, which increasingly relies on adhesives. The substrates that need to be bonded in battery modules are diverse, ranging from polyethylene terephthalate (PET), polycarbonate (PC), electrophoretically coated steel, and electrophoretically coated aluminum. A suitable structural adhesive should provide good adhesion to a wide variety of substrates without requiring pre-treatment. Additional requirements include moderate elastic modulus, weather resistance, and reasonable cost. Two-component (2K) polyurethane structural adhesives containing both polyisocyanate and polyol components have become a good choice.

[0002] However, compared to epoxy or acrylate structural adhesives, structural 2K polyurethane adhesives are particularly sensitive to moisture during storage and curing. If moisture in the adhesive packaging is not completely expelled, the isocyanate component will be unstable, leading to a significant increase in viscosity and a tendency for surface crusting during storage. Additionally, when the adhesive has been applied to bonding equipment, crusting issues can arise with the isocyanate component if the seal between the adhesive packaging and the press plate is poor, or if the production line has been shut down for an extended period. If the crust is not removed promptly, the mixing pipes of the equipment may become clogged, and equipment parts will suffer wear, negatively impacting the production line. There is a need in the art for improved structural adhesives to address these problems. Summary of the Invention

[0003] An uncured two-component adhesive formulation is disclosed, comprising: (a) an isocyanate component comprising an isocyanate-terminated prepolymer prepared from a polyisocyanate and a hydrophobic polyol; and (b) a polyol component comprising: (i) a polyol; and (ii) a catalyst capable of catalyzing the reaction of hydroxyl groups with isocyanate groups; wherein the uncured adhesive formulation is in the form of a kit, and the isocyanate component and the polyol component are not mixed in the kit.

[0004] A method for adhering two or more substrates is also described, the method comprising: mixing an isocyanate component and a polyol component of the adhesive formulation to produce an adhesive mixture; applying the adhesive mixture to a first substrate; contacting a second substrate with the first substrate; and curing the adhesive mixture thereby adhering the two or more substrates together.

[0005] An adhesive component is also described, comprising: a first substrate; a second substrate; and a cured adhesive mixture at least partially between the first substrate and the second substrate, the cured adhesive mixture being produced by mixing an isocyanate component and a polyol component of the adhesive formulation to produce the adhesive mixture, and curing the adhesive mixture. Detailed Implementation

[0006] The inventors have discovered that when a two-part polyurethane adhesive contains an isocyanate component comprising a prepolymer produced by the reaction of a polyisocyanate and a hydrophobic polyol, the isocyanate component exhibits excellent moisture resistance and storage stability, and produces an adhesive exhibiting good adhesive properties when reacted with the polyol component.

[0007] I. Adhesive formulations

[0008] A. Isocyanate component

[0009] The isocyanate component comprises a prepolymer prepared by reacting at least one polyisocyanate with at least one hydrophobic polyol to produce an isocyanate-terminated prepolymer.

[0010] i. Polyisocyanates

[0011] There are no particular limitations on polyisocyanates. They can be aliphatic or aromatic. Examples of suitable aliphatic polyisocyanates include hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), methylene dicyclohexyl diisocyanate, trimethyl hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, and mixtures thereof.

[0012] Examples of suitable aromatic polyisocyanates include methylene-bis-(phenyl isocyanate) (MDI), polymethylene polyphenyl isocyanate, tetramethylxylene diisocyanate, and toluene diisocyanate, any of which may be modified to include biuret, urethane, urea, carbamate, isocyanurate, or carbodiimide groups. MDI includes 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI. In one embodiment, the polyisocyanate comprises or is composed of MDI. In another embodiment, the polyisocyanate comprises or is composed of polymeric MDI. For example, in a specific embodiment, the polyisocyanate comprises or is composed of polymeric MDI with an average functionality of 2.7. In another specific embodiment, the polyisocyanate comprises or is composed of MDI with an average functionality of 2. In yet another embodiment, the polyisocyanate comprises MDI with an average functionality of 2 and a molecular weight (M... n It is a mixture of 2,4'-MDI and 4,4'-MDI, or composed of them, with a Da of 250. n"This should be understood as the average molecular weight of the index."

[0013] Equivalents and molecular weights were measured by gel permeation chromatography (GPC) using a Malvern Viscothek GPC max instrument. Tetrahydrofuran (THF) was used as the eluent, a PL GEL MIXED D (Agilent, 300 x 7.5 mm, 5 µm) column was used, and a Malvern Viscothek TDA (integrated refractive index viscometer and light scattering) was used as the detector.

[0014] ii. Hydrophobic polyols

[0015] Typically, hydrophobic polyols are polyols that form different phases when mixed with water. For example, different phases can be formed when a hydrophobic polyol is mixed with water in a 1:1 ratio. In some embodiments, the hydrophobicity of the polyol can be defined by the water contact angle (i.e., the geometry of water on a flat film of the polyol, particularly the angle between the edge of the droplet and the surface of the polyol below it). If the droplet forms a sphere that barely touches the surface of the polyol being tested, the contact angle is greater than 90°. Therefore, in some embodiments, hydrophobic polyols have water contact angles greater than 90°, for example, 100° or greater, 105° or greater, or 110° or greater.

[0016] In some embodiments, the hydrophobic polyol constitutes at least 75 wt%, for example at least 80 wt%, at least 90 wt%, and in some cases 100 wt% of the total polyol content of the isocyanate-terminated prepolymer.

[0017] In one embodiment, the hydrophobic polyol is a cashew nut shell oil polyol, a polyester polyol, a polybutadiene polyol, a polyether / polyester polyol, or any combination thereof. In some embodiments, the hydrophobic polyol is a branched polyether / polyester polyol; a cashew nut shell oil polyol with an average functionality of 3.3; M n A polyester polyol with a density of 1,000 Da; M n Hydroxyl-terminated polybutadiene with a Da of 2,800 and a functionality of 2.3; hydroxyl-terminated polyester polyols, such as hydroxyl-terminated polyester polyols made from adipic acid, 1,6-hexanediol and 2,2-dimethyl-1,3-propanediol; or any combination thereof.

[0018] Isocyanate-terminated prepolymers can be prepared by reacting at least one polyisocyanate with at least one hydrophobic polyol. This reaction can be carried out at elevated temperatures under a vacuum or inert atmosphere (e.g., nitrogen, argon). For example, the at least one polyisocyanate can be reacted with the at least one hydrophobic polyol at 100°C-130°C, for example, 120°C or about 120°C. The prepolymer can be prepared using a stoichiometric excess of isocyanate groups, producing an NCO-terminated prepolymer. The prepolymer can be separated after the reaction, or it can be used as is in the formulation of the isocyanate component of an adhesive.

[0019] An exemplary prepolymer is produced by the reaction of the following pairs of polyisocyanates and polyols:

[0020]

[0021] Based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer, the amount of polyisocyanate used to make the prepolymer can range from 60-85 wt%, for example 65-80 wt%, or 70-78 wt%. Based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer, the amount of hydrophobic polyol used to make the isocyanate-terminated prepolymer can range from 15-40 wt%, for example 20-35 wt%, or 22-30 wt%.

[0022] In one embodiment, the isocyanate-terminated prepolymer is made using 60-85 wt% MDI, for example 65-80 wt% MDI, or 70-78 wt% MDI, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0023] In another embodiment, the isocyanate-terminated prepolymer is made using 15-40 wt% castor oil, for example 20-35 wt% or 22-30 wt% castor oil, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer. In yet another embodiment, the isocyanate-terminated prepolymer is made using 15-40 wt% polyether / polyester polyol, for example 20-35 wt% or 22-30 wt% polyether / polyester polyol, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0024] In one embodiment, the isocyanate-terminated prepolymer is made using 15-40 wt% cashew nutshell oil polyol, such as 20-35 wt% cashew nutshell oil polyol, or 22-30 wt% cashew nutshell oil polyol, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0025] In another embodiment, the isocyanate-terminated prepolymer is made using 15-40 wt% polyester polyol, such as 20-35 wt% or 22-30 wt% polyester polyol, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0026] In another embodiment, the isocyanate-terminated prepolymer is made using 15-40 wt% polybutadiene polyol, such as 20-35 wt% or 22-30 wt% polybutadiene polyol, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0027] In one embodiment, the isocyanate-terminated prepolymer is made using 15-40 wt% of cashew nutshell oil polyol with an average functionality of about 3.3 based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer, for example 20-35 wt% of cashew nutshell oil polyol with an average functionality of about 3.3, or 22-30 wt% of cashew nutshell oil polyol with an average functionality of about 3.3.

[0028] In another embodiment, the isocyanate-terminated prepolymer is made using 15-40 wt% of a hydroxyl-terminated polyester polyol with a total weight of 1,000 Da (MWT) based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer, such as 20-35 wt% of a hydroxyl-terminated polyester polyol with a total weight of 1,000 Da (MWT), or 22-30 wt% of a hydroxyl-terminated polyester polyol with a total weight of 1,000 Da (MWT).

[0029] In another embodiment, the isocyanate-terminated prepolymer is made using 15-40 wt% of hydroxyl-terminated polybutadiene with a total weight of 2,800 Da MWT and a functionality of 2.3 based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer, such as 20-35 wt% of hydroxyl-terminated polybutadiene with a total weight of 2,800 Da MWT and a functionality of 2.3, or 22-30 wt% of hydroxyl-terminated polybutadiene with a total weight of 2,800 Da MWT and a functionality of 2.3.

[0030] In another embodiment, the isocyanate-terminated prepolymer uses 15-40 wt% of a hydroxyl-terminated polyester polyol made from adipic acid, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol, or with an average molecular weight of 830 Da and a functionality of 2, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer. For example, 20-35 wt% of a hydroxyl-terminated polyester polyol made from adipic acid, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol, or with an average molecular weight of 830 Da and a functionality of 2, or 22-30 wt% of a hydroxyl-terminated polyester polyol made from adipic acid, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol, or with an average molecular weight of 830 Da and a functionality of 2.

[0031] B. Polyol Components

[0032] The polyol component comprises at least one polyol and at least one catalyst capable of catalyzing the reaction between hydroxyl groups and isocyanate groups.

[0033] i. Polyols

[0034] There are no particular limitations on the at least one polyol used in the polyol component. In one embodiment, the at least one polyol comprises a polyether polyol, such as poly(C) 2-4 -Epoxyalkylene) polyols or those comprising the same. In another embodiment, the at least one polyol is a poly(propylene oxide) polyol. The polyol may have a functionality of 2.5-3.5, for example, 3. In one embodiment, the at least one polyol comprises a functionality of 2.5-3.5, for example, 3, and M n The polyol is a polyol with a concentration of 300-3,000 Da or composed thereof. In one embodiment, the at least one polyol comprises a mixture of two or more polyols, such as a mixture of two or more polyether polyols or composed thereof.

[0035] In one embodiment, the at least one polyol comprises a functionality of 3 and M n The first polyether polyol has a capacity of 3,000 Da and a functionality of 3 and M n It is a mixture of or composed of a second polyether polyol with a capacity of 350 Da. In another embodiment, the at least one polyol comprises a functionality of 3 and M n The first polyol based on poly(propylene oxide) with a capacity of 3,000 Da and a functionality of 3 and M n It is a mixture of or composed of a second poly(propylene oxide) based polyol with a value of 350 Da.

[0036] In one embodiment, the at least one polyol comprises a functionality of 3 and M nThe first polyol based on poly(propylene oxide) with a capacity of 3,000 Da and a functionality of 3 and M n It is a mixture of or consisting of a second poly(propylene oxide)-based polyol of approximately 50:50 (wt:wt) or thereof, which is 350 Da. The at least one polyol may be used at 40-80 wt%, for example 50-70 wt%, or 55-65 wt%, based on the total weight of the polyol components.

[0037] In one embodiment, the at least one polyol comprises 25-35 wt% of a functionality of 3 and M based on the total weight of the polyol components. n The first poly(propylene oxide)-based polyol with a Da of 3,000 and 25-35 wt% having a functionality of 3 and M n It is a second polyol based on poly(propylene oxide) or composed of it, with a Da of 350.

[0038] ii. catalyst

[0039] The polyol component contains at least one catalyst capable of catalyzing the reaction between hydroxyl groups and isocyanate groups. Examples of such catalysts include tertiary amine catalysts; organometallic catalysts such as bismuth catalysts, alkyltin carboxylates, alkyltin oxides, and tin thiolates.

[0040] Specific examples of tertiary amine catalysts include N-methylmorpholine, N-methylimidazolium, triethylenediamine, bis-(2-dimethylaminoethyl)-ether, 1,4-diazabicyclo[2.2.2]octane (DABCO), dimethylcyclohexylamine, dimethylethanolamine, 2,2-dimorpholino-diethyl ether (DMDEE), N,N,N-dimethylaminopropylhexahydrotriazine, dimethyltetrahydropyrimidine, tetramethylethylenediamine, dimethylcyclohexylamine, 2,2-N,N-benzyldimethylamine, and dimethylethanolamine. Dimethylaminopropylamine, penta-dimethyldiethylenetriamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N',N'-trimethylaminoethylpiperazine, 1,1'-[[3-(dimethylamino)propyl]imino]bisprop-2-ol, 1,3,5-tris[3-(dimethylamino)propyl]hexahydro-1,3,5-triazine, NN-dimethyldipropylenetriamine, N,N,N'-trimethylaminoethylethanolamine, of which DMDEE is particularly preferred.

[0041] If an organometallic catalyst is used, it is any organometallic catalyst capable of catalyzing the reaction of isocyanates with a functional group having at least one reactive hydrogen. Examples include bismuth catalysts, metal carboxylates such as tin carboxylate and zinc carboxylate. Metal alkanoates include stannous octanoate, bismuth octanoate, or bismuth neodecanoate. Preferably, the at least one organometallic catalyst is a bismuth catalyst or an organotin catalyst. Examples include dibutyltin dilaurate, dimethyltin dinedecanoate, dimethyltin thiol, dimethyltin carboxylate, dimethyltin dioleate, dimethyltin dithioglycolate, dibutyltin thiol, bis(2-ethylhexyl thioglycolate) dibutyltin, dibutyltin sulfide, dioctyltin dithioglycolate, dioctyltin thiol, dioctyltin dioctanoate, dioctyltin dinedecanoate, and dioctyltin dilaurate. In particularly preferred embodiments, it is a tin catalyst or dioctyltin thiol.

[0042] The catalyst can be used at a concentration of 0.005 to 0.02 wt%, for example, 0.01 wt%, based on the total weight of the polyol components. In one specific embodiment, the catalyst is dioctyltin thiol, which is used at a concentration of 0.01 to 0.02 wt%, based on the total weight of the polyol components.

[0043] C. Optional ingredients

[0044] Any component of the adhesive formulation may additionally contain additives commonly used in polyurethane adhesives. Examples of optional components include fillers such as talc, calcium carbonate, fumed silica, carbon black, zeolite, molecular sieves, and mixtures thereof.

[0045] In one embodiment, any one or both components comprise calcium carbonate, for example, at 25-40 wt% or 29-38 wt% based on the total weight of the respective components. In another embodiment, any one or both components comprise fumed silica, for example, at 1-4 wt% or 1.5-3 wt% based on the total weight of the respective components. In one embodiment, any one or both components comprise calcium carbonate, for example, at 25-40 wt% or 29-38 wt% based on the total weight of the respective components, and any one or both components comprise fumed silica, for example, at 1-4 wt% or 1.5-3 wt% based on the total weight of the respective components.

[0046] II. Manufacturing and usage methods

[0047] The adhesive composition can be made by, for example, mixing each component separately under inert and dry conditions and / or under vacuum until a homogeneous mixture is obtained. Once each component is mixed, they are stored in separate containers until use.

[0048] In one embodiment, the method of use involves providing a two-component adhesive comprising: (a) an isocyanate component having a prepolymer prepared by reacting at least one polyisocyanate with at least one hydrophobic polyol to produce an isocyanate-terminated prepolymer; and (b) a polyol component comprising: at least one polyol; and at least one catalyst capable of catalyzing the reaction of hydroxyl groups with isocyanate groups. The two components can then be mixed to produce an adhesive mixture. The adhesive mixture can be applied to a first substrate, which can then be brought into contact with a second substrate. The adhesive mixture can be cured to provide an bonded assembly.

[0049] As described above, one way to provide each component of the adhesive is in an airtight container, such as an airtight sealed tube. The container can be opened immediately before use. Mixing each component or two components together can be done by any means to obtain a homogeneous mixture. In one embodiment, the mixing ratio of each component is 0.5:1 to 1:0.5 (v:v), for example 1:1.2 to 1.2:1 (v:v), or 1:1 (v:v). The adhesive mixture can be applied manually or with robotic equipment by any application method, including, for example, by spreading or application via a nozzle.

[0050] In one embodiment, one or both of the first and second substrates are selected from metals, such as Ni-plated steel and / or aluminum. In another embodiment, one or both of the first and second substrates are selected from metals, including electrophoretically coated aluminum, electrophoretically coated steel, laser-treated metal surfaces, and metal surfaces treated with plasma or flame. Plasma pretreatment may include plasma processes that further chemically modify or treat the surface, such as plasmaplus. One of these plasmaplus treatments includes silane functionalization of the metal surface. Other substrates include coated metals and metal surfaces modified with functional foils. Coatings, epoxy-based coatings, and acrylic coatings. The foils are primarily PET-based. Typically, curing begins as soon as the components are mixed. Typical curing conditions are 3 to 7 days at 23°C.

[0051] The disclosed formulation produces an isocyanate component exhibiting improved storage stability, as demonstrated by a longer “skinning time.” The skinning time is measured by exposing beads of the isocyanate component at 23°C to 50% relative humidity and measuring the time until the isocyanate component begins to cure and forms a skin from the outside in.

[0052] The isocyanate component of the adhesive can exhibit a skinning time of 10 hours or longer, for example, 11 hours or longer, 12 hours or longer, or 15 hours or longer. In some embodiments, improved storage stability does not impair the adhesive properties of the cured adhesive. Adhesive mixtures produced from each component in a 1:1 (v:v) ratio, after curing for seven days at 23°C and 50% relative humidity, exhibit an lap shear strength of 10 MPa or greater, for example, 12 MPa or greater, or 13 MPa or greater, measured using DIN EN 1465, with a bond area of ​​10 x 25 = 250 mm². 2 The adhesive layer was 1 mm thick, and the substrate was electrophoretically coated steel and electrophoretically coated steel; all surfaces were prepared by solvent cleaning, and the sample was pulled and sheared at 5 mm / min during the test.

[0053] III. Exemplary embodiments

[0054] The following are exemplary embodiments of the adhesive composition and its manufacturing and application methods:

[0055] (1) A two-component adhesive comprising: an isocyanate component comprising a prepolymer prepared by reacting at least one polyisocyanate with at least one hydrophobic polyol to produce an isocyanate-terminated prepolymer; and a polyol component comprising: at least one polyol; and at least one catalyst capable of catalyzing the reaction of hydroxyl groups with isocyanate groups. The adhesive formulation may be in the form of a kit in which the two components are not mixed before use.

[0056] (2) A method for adhering two or more substrates, the method comprising the steps of: providing a two-component adhesive comprising: an isocyanate component comprising a prepolymer prepared by reacting at least one polyisocyanate with at least one hydrophobic polyol to produce an isocyanate-terminated prepolymer; a polyol component comprising: at least one polyol; at least one catalyst capable of catalyzing the reaction of hydroxyl groups with isocyanate groups; mixing the two components to produce an adhesive mixture; applying the adhesive mixture to a first substrate; bonding a second substrate to the first substrate; and curing the adhesive mixture.

[0057] (3) An adhesive component comprising: a first substrate; a second substrate; a cured adhesive mixture produced by mixing a two-component adhesive comprising: an isocyanate component comprising a prepolymer prepared by reacting at least one polyisocyanate with at least one hydrophobic polyol to produce an isocyanate-terminated prepolymer; a polyol component comprising: at least one polyol; at least one catalyst capable of catalyzing the reaction of hydroxyl groups with isocyanate groups; wherein the first substrate and the second substrate are in adhesive contact with the cured adhesive mixture.

[0058] As described in Examples 1, 2 or 3, wherein the at least one polyisocyanate used to make the prepolymer is aromatic or aliphatic.

[0059] As described in any of the foregoing embodiments, the at least one polyisocyanate used to make the prepolymer is aromatic.

[0060] As described in any one of Examples 1-4, wherein the at least one polyisocyanate used to prepare the prepolymer is selected from hexamethylene diisocyanate (HMDI), isophorone diisocyanate, methylene dicyclohexyl diisocyanate, trimethyl hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, and mixtures thereof.

[0061] As described in any one of Examples 1-5, wherein the at least one polyisocyanate used to prepare the prepolymer is selected from methylene-bis-(phenyl isocyanate) (MDI), polymethylene polyphenyl isocyanate, tetramethylxylene diisocyanate, toluene diisocyanate, any one of which may be modified to include biuret, urethane, urea, carbamate, or carbodiimide groups, and mixtures thereof.

[0062] As described in any one of Examples 1-5, wherein the at least one polyisocyanate used to prepare the prepolymer is selected from 2,2'-MDI, 2,4'-MDI, 4,4'-MDI, and mixtures thereof.

[0063] As described in any one of Examples 1-5, wherein the at least one polyisocyanate used to prepare the prepolymer is selected from polymeric MDI.

[0064] As described in any one of Examples 1-5, wherein the at least one polyisocyanate used to make the prepolymer comprises or is composed of polymeric MDI having an average functionality of 2.7.

[0065] As described in any one of Examples 1-5, wherein the at least one polyisocyanate used to prepare the prepolymer comprises or is composed of MDI having an average functionality of 2.

[0066] As described in any one of Examples 1-5, wherein the at least one polyisocyanate used to prepare the prepolymer comprises an average functionality of 2 and a molecular weight (M n It is a mixture of 2,4'-MDI and 4,4'-MDI of 250 Da or composed of them.

[0067] As described in any of the foregoing embodiments, wherein the at least one hydrophobic polyol constitutes at least 75 wt%, for example at least 80 wt%, or at least 90 wt%, and in some cases 100 wt% of the total polyol content of the isocyanate-terminated prepolymer.

[0068] As described in any of the foregoing embodiments, the at least one hydrophobic polyol is selected from cashew nut shell oil polyols, polyester polyols, polybutadiene polyols, polyether / polyester polyols, and mixtures thereof.

[0069] As described in any of the foregoing embodiments, wherein the at least one hydrophobic polyol is selected from branched polyether / polyester polyols; cashew nut shell oil polyol with an average functionality of 3.3; M n A polyester polyol with a density of 1,000 Da; M n Hydroxyl-terminated polybutadiene with a Da of 2,800 and a functionality of 2.3; hydroxyl-terminated polyester polyols, particularly hydroxyl-terminated polyester polyols made from adipic acid, 1,6-hexanediol and 2,2-dimethyl-1,3-propanediol.

[0070] As described in any of the foregoing embodiments, the prepolymer is prepared using a stoichiometric excess of isocyanate groups to produce NCO-terminated molecules.

[0071] As described in any of the foregoing embodiments, the prepolymer is produced by the reaction of the following pairs of polyisocyanates and polyols:

[0072]

[0073] As described in any of the foregoing embodiments, the prepolymer is produced by the reaction of the following pairs of polyisocyanates and polyols:

[0074]

[0075] As described in any of the foregoing embodiments, the amount of polyisocyanate used to make the prepolymer is 60-85 wt%, for example 65-80 wt%, or 70-78 wt%, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0076] As described in any of the foregoing embodiments, the amount of hydrophobic polyol used to make the isocyanate-terminated prepolymer is 15-40 wt%, for example 20-35 wt%, or 22-30 wt%, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0077] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer is made using 60-85 wt% MDI, for example 65-80 wt% MDI, or 70-78 wt% MDI based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0078] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer is made using 15-40 wt% castor oil, for example 20-35 wt% castor oil, or 22-30 wt% castor oil based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0079] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer is made using 15-40 wt% polyether / polyester polyol, for example 20-35 wt% polyether / polyester polyol, or 22-30 wt% polyether / polyester polyol based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0080] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer is made using 15-40 wt% cashew nutshell oil polyol, for example 20-35 wt% cashew nutshell oil polyol, or 22-30 wt% cashew nutshell oil polyol based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0081] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer is made using 15-40 wt% polyester polyol, such as 20-35 wt% or 22-30 wt% polyester polyol, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0082] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer is made using 15-40 wt% polybutadiene polyol, such as 20-35 wt% or 22-30 wt% polybutadiene polyol, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer.

[0083] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer is made using 15-40 wt% of cashew nutshell oil polyol with an average functionality of about 3.3, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer, for example 20-35 wt% of cashew nutshell oil polyol with an average functionality of about 3.3, or 22-30 wt% of cashew nutshell oil polyol with an average functionality of about 3.3.

[0084] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer is made using 15-40 wt% of a hydroxyl-terminated polyester polyol with a total MWT of 1,000 Da based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer, such as 20-35 wt% of a hydroxyl-terminated polyester polyol with a MWT of 1,000 Da, or 22-30 wt% of a hydroxyl-terminated polyester polyol with a MWT of 1,000 Da.

[0085] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer is made using 15-40 wt% of hydroxyl-terminated polybutadiene with a total weight of 2,800 Da MWT and 2.3 based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer, such as 20-35 wt% of hydroxyl-terminated polybutadiene with a total weight of 2,800 Da MWT and 2.3, or 22-30 wt% of hydroxyl-terminated polybutadiene with a total weight of 2,800 Da MWT and 2.3.

[0086] As described in any of the foregoing embodiments, the isocyanate-terminated prepolymer uses 15-40 wt% of a hydroxyl-terminated polyester polyol made from adipic acid, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol, or with an average molecular weight of 830 Da and a functionality of 2, based on the total weight of the polyisocyanate and hydrophobic polyol used to make the prepolymer. For example, 20-35 wt% of a hydroxyl-terminated polyester polyol made from adipic acid, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol, or with an average molecular weight of 830 Da and a functionality of 2, or 22-30 wt% of a hydroxyl-terminated polyester polyol made from adipic acid, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol, or with an average molecular weight of 830 Da and a functionality of 2.

[0087] As described in any of the foregoing embodiments, wherein the at least one polyol comprises or is composed of a polyether polyol, for example, the polyether polyol is selected from poly(C) 2-4 -Epoxyalkylene) polyols.

[0088] As described in any of the foregoing embodiments, wherein the at least one polyol is selected from poly(propylene oxide) polyols.

[0089] As described in any of the foregoing embodiments, the at least one polyol has a functionality of 2.5-3.5, for example, 3.

[0090] As described in any of the foregoing embodiments, the at least one polyol comprises a functionality of 2.5-3.5, for example 3, and M n It is a polyol with a Da of 300-3,000 or composed of such polyols.

[0091] As described in any of the foregoing embodiments, wherein the at least one polyol comprises a mixture of two or more polyols, particularly a mixture of two or more polyether polyols, or is composed of the same.

[0092] As described in any of the foregoing embodiments, wherein the at least one polyol comprises a functionality of 3 and M n The first polyether polyol is 3,000 Da and has a functionality of 3 and M n It is a mixture of or composed of a second polyether polyol with a Da of 350.

[0093] As described in any of the foregoing embodiments, wherein the at least one polyol comprises a functionality of 3 and M n The first polyol based on poly(propylene oxide) with a capacity of 3,000 Da and a functionality of 3 and M n It is a mixture of or composed of a second poly(propylene oxide) based polyol with a value of 350 Da.

[0094] As described in any of the foregoing embodiments, wherein the at least one polyol comprises a functionality of 3 and M n The first polyol based on poly(propylene oxide) with a capacity of 3,000 Da and a functionality of 3 and M n It is a mixture of or composed of a second poly(propylene oxide) based polyol of approximately 50:50 (wt:wt) or of the same.

[0095] As described in any of the foregoing embodiments, the at least one polyol is used at 40-80 wt%, for example 50-70 wt%, particularly 55-65 wt%, based on the total weight of the polyol components.

[0096] As described in any of the foregoing embodiments, wherein the at least one polyol comprises 25-35 wt% of a functionality of 3 and M based on the total weight of the polyol components. n The first poly(propylene oxide) based polyol with a Da of 3,000 and 25-35 wt% with a functionality of 3 and M n It is a second polyol based on poly(propylene oxide) or composed of it, with a Da of 350.

[0097] As described in any of the foregoing embodiments, the at least one catalyst is selected from tertiary amine catalysts; organometallic catalysts, such as bismuth catalysts, alkyltin carboxylates, alkyltin oxides, and tin thiols.

[0098] As described in any of the foregoing embodiments, the at least one catalyst is selected from N-methylmorpholine, N-methylimidazolium, triethylenediamine, bis-(2-dimethylaminoethyl)-ether, 1,4-diazabicyclo[2.2.2]octane (DABCO), dimethylcyclohexylamine, dimethylethanolamine, 2,2-dimorpholino-diethyl ether (DMDEE), N,N,N-dimethylaminopropylhexahydrotriazine, dimethyltetrahydropyrimidine, tetramethylethylenediamine, dimethylcyclohexylamine, 2,2-N,N-benzyldimethylamine, etc. Dimethylethanolamine, dimethylaminopropylamine, penta-dimethyldiethylenetriamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N',N'-trimethylaminoethylpiperazine, 1,1'-[[3-(dimethylamino)propyl]imino]bisprop-2-ol, 1,3,5-tris[3-(dimethylamino)propyl]hexahydro-1,3,5-triazine, NN-dimethyldipropylenetriamine, N,N,N'-trimethylaminoethylethanolamine, wherein DMDEE is particularly preferred.

[0099] As described in any of the foregoing embodiments, the at least one catalyst is selected from bismuth catalysts; metal carboxylates, such as tin carboxylate and zinc carboxylate; metal chain alkanoates, including stannous octoate, bismuth octoate, or bismuth neodecanoate.

[0100] As described in any of the foregoing embodiments, the at least one catalyst is selected from bismuth catalysts and organotin catalysts.

[0101] As described in any of the foregoing embodiments, the at least one catalyst is selected from dibutyltin dilaurate, dimethyltin dinedecanoate, dimethyltin thiolate, dimethyltin carboxylate, dimethyltin dioleate, dimethyltin dithioglycolate, dibutyltin thiolate, dibutyltin bis(2-ethylhexyl thioglycolate) dibutyltin, dibutyltin sulfide, dioctyltin dithioglycolate, dioctyltin thiolate, dioctyltin dioctanoate, dioctyltin dinedecanoate, and dioctyltin dilaurate.

[0102] As described in any of the foregoing embodiments, wherein the at least one catalyst is dioctyltin thiols.

[0103] As described in any of the foregoing embodiments, the catalyst is used at a weight of 0.005 to 0.02 wt%, for example 0.01 wt%, based on the total weight of the polyol components.

[0104] As described in any of the foregoing embodiments, the catalyst is dioctyltin thiol, used at 0.01 to 0.02 wt% based on the total weight of the polyol components.

[0105] As described in any of the foregoing embodiments, the isocyanate component and / or polyol component additionally comprise fillers such as talc, calcium carbonate, fumed silica, carbon black, zeolite, molecular sieve, and mixtures thereof.

[0106] As described in any of the foregoing embodiments, wherein the isocyanate component and / or polyol component comprises calcium carbonate, preferably in a total weight of 25-40 wt%, for example 29-38 wt%, based on the respective portions.

[0107] As described in any of the foregoing embodiments, the isocyanate component and / or polyol component comprises fumed silica, preferably in the form of 1-4 wt%, for example 1.5-3 wt%, based on the total weight of the respective portions.

[0108] As described in any of the foregoing embodiments, wherein the isocyanate component and / or polyol component comprises calcium carbonate, preferably in an amount of 25-40 wt%, for example 29-38 wt%, based on the total weight of the respective components, and wherein the isocyanate component and polyol component comprise fumed silica, preferably in an amount of 1-4 wt%, for example 1.5-3 wt%, based on the total weight of the respective components. Example

[0109] IV. preparation

[0110]

[0111] A. Prepolymer Preparation

[0112] The isocyanate-terminated prepolymers are made using the ingredients listed in Table 2.

[0113] The prepolymer was prepared in a 2 L four-necked flask equipped with a mechanical stir bar and a thermometer. The prepolymer was then separated and stored. The method for preparing the prepolymer is described based on Example 4 (IE4) of this invention:

[0114] At room temperature, 340 g of castor oil was added to a four-necked flask equipped with a mechanical stir bar and a thermometer. The oil was dried under reduced pressure at 120°C for 1 h. The oil was then cooled to 80°C, and 1,020 g of SUPRASEC 2020 was added to the flask, and the mixture was reacted under reduced pressure at 80°C for 2 h. The resulting prepolymer was then stored under airtight conditions.

[0115] Prepolymers were prepared by using a significant stoichiometric excess of MDI to produce MDI-terminated polyols.

[0116] B. Preparation of Adhesive Part A and Part B

[0117] The isocyanate component (part A) and polyol component (part B) of the adhesive were prepared in a 2 L planetary mixer (laboratory-scale mixer).

[0118] Based on Example 4 (IE4) of this invention, the method for preparing the adhesive is described as follows:

[0119] Dry all solid raw materials (such as CaCO3 and CAB-O-SIL TS-720) at 150°C for 24 hours or longer until the moisture content is less than 300 ppm.

[0120] Add 680 g of prepolymer, 300 g of CaCO3, and 20 g of CAB-O-SIL TS-720 (both pre-dried) to a 2 L planetary mixer (laboratory-scale mixer). Stir the mixture for 30 minutes. Apply a vacuum of up to 80 mbar and continue mixing for another 30 minutes. Break the vacuum with nitrogen and package the binder components in sealed cylinders.

[0121]

[0122] V. Characterization and Results

[0123] A. Working hours

[0124] Mix portions A and B in a 1:1 volume:volume ratio. The working time is the time it takes for the Brinell viscosity to increase by 2X from its initial value at 23°C and 5 rpm using a #14 rotor.

[0125] Brookfield viscosity was measured at 23°C using a Brookfield DV2T with a shear rate of 5 rpm and a 14# rotor.

[0126] B. Skin formation time

[0127] The skinning time is the time when the isocyanate component ISOC (part A) begins to form a skin from the outside in when exposed to 23°C / 50% relative humidity.

[0128] C. Lap shear strength

[0129] Mix portions A and B in a 1:1 volume:volume ratio. lap shear strength was measured using DIN EN 1465; bonded area: 10 x 25 = 250 mm². 2 Adhesive layer thickness: 1 mm; Substrate: Electrophoretic coated steel; Clean all surfaces with ethanol or isopropanol; Curing conditions: 7 days @ 23°C; During testing, pull and shear the sample at 5 mm / min.

[0130] D. Tensile properties

[0131] Tensile properties, including tensile strength, E-modulus, and elongation, were measured according to DIN EN ISO 527-2; curing conditions: 7 days @ 23°C; during testing, the samples were stretched at 50 mm / min. The results are listed in Table 2.

[0132] Comparative examples 1, 2, and 3 contain various polyisocyanates and hydrophilic polyols (M... n ISO components (part A) of the prepolymers made from polypropylene glycol (2,000 Da and functionality 2) all exhibited skinning times of less than 5 hours. In contrast, ISO components of the prepolymers of Examples 4-9 of the present invention, containing the same polyisocyanate and various hydrophobic polyols (castor oil, SOVERMOL 805, GX-9007, PRIPLAST 1837, PBD R45 M, and XCP-830NH), exhibited skinning times of more than 12 hours. Significantly, the other properties of the adhesives of Examples 4-9 of the present invention are acceptable.

[0133] The features and advantages of this disclosure are apparent from the detailed description, and the claims cover all such features and advantages. Many variations will occur to those skilled in the art, and any variations equivalent to those described herein fall within the scope of this disclosure. Those skilled in the art will understand that the concepts upon which this disclosure is based can serve as the basis for designing other compositions and methods for carrying out the various purposes of this disclosure. Therefore, the claims should not be considered as limiting to the specification or examples.

Claims

1. An uncured two-component adhesive formulation, said adhesive formulation having: a) An isocyanate component comprising an isocyanate-terminated prepolymer prepared from a polyisocyanate and a hydrophobic polyol; and b) Polyol components, which include: i) Polyols; and ii) Catalysts capable of catalyzing the reaction between hydroxyl groups and isocyanate groups; The uncured adhesive formulation is in the form of a kit, and the isocyanate component and the polyol component are not mixed in the kit.

2. The adhesive formulation as claimed in claim 1, wherein, The polyisocyanate is aromatic.

3. The adhesive formulation as claimed in claim 1, wherein, The polyisocyanate is methylene-bis-(phenylisocyanate) (MDI), polymethylene polyphenylisocyanate, tetramethylxylene diisocyanate, toluene diisocyanate or its derivatives, or any combination thereof.

4. The adhesive formulation as claimed in claim 1, wherein, The polyisocyanate is 2,2'-MDI, 2,4'-MDI, 4,4'-MDI, or a combination thereof.

5. The adhesive formulation as claimed in claim 1, wherein, The hydrophobic polyol has a water contact angle greater than 90°.

6. The adhesive formulation as claimed in claim 1, wherein, The hydrophobic polyol constitutes at least 75 wt% of the total polyol content of the isocyanate-terminated prepolymer.

7. The adhesive formulation as claimed in claim 1, wherein, Hydrophobic polyols are cashew nut shell oil polyols, polyester polyols, polybutadiene polyols, polyether / polyester polyols, or any combination thereof.

8. The adhesive formulation as claimed in claim 1, wherein, The hydrophobic polyol is a branched polyether / polyester polyol, a cashew nut shell oil polyol with an average functionality of 3.3, and a molecular weight (M). n Polyester polyols with a molecular weight of 1,000 Da and a molecular weight of M n Hydroxyl-terminated polybutadiene or hydroxyl-terminated polyester polyol with a Da of 2,800 and a functionality of 2.

3.

9. The adhesive formulation as claimed in claim 1, wherein, The isocyanate-terminated prepolymer is prepared from an aromatic polyisocyanate and one or more of the following hydrophobic polyols: - Castor oil; - Polyether / polyester polyols; - Cashew shell oil polyols; - Polyester polyols; or - Polybutadiene polyol.

10. The adhesive formulation of claim 9, wherein, The aromatic polyisocyanate is methylene-bis-(phenylisocyanate) (MDI).

11. The adhesive formulation of claim 9, wherein, The isocyanate-terminated prepolymer is prepared using 15-40 wt% of the hydrophobic polyol based on the total weight of the polyisocyanate and the hydrophobic polyol.

12. The adhesive formulation of claim 9, wherein, The isocyanate-terminated prepolymer is prepared using 20-35 wt% of the hydrophobic polyol based on the total weight of the polyisocyanate and the hydrophobic polyol.

13. The adhesive formulation of claim 9, wherein, The isocyanate-terminated prepolymer is prepared using 22-30 wt% of the hydrophobic polyol based on the total weight of the polyisocyanate and the hydrophobic polyol.

14. A method for adhering two or more substrates, the method comprising: a) Mixing the isocyanate component and the polyol component of the adhesive formulation as described in claim 1 to produce an adhesive mixture; b) Apply the adhesive mixture to the first substrate; c) Make the second substrate come into contact with the first substrate; as well as d) Curing the adhesive mixture.

15. An adhesive component comprising: a) First substrate; b) Second substrate; and c) an adhesive mixture cured at least partially between the first substrate and the second substrate, the cured adhesive mixture being produced by mixing the isocyanate component and the polyol component of the adhesive formulation as claimed in claim 1 to produce the adhesive mixture, and curing the adhesive mixture.

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