One-component polyurethane sealant compositions, articles thereof, and methods of making same

Abstract

The present invention relates to a one-component moisture-curable polyurethane sealant composition comprising an isocyanate-terminated polyurethane prepolymer wherein the isocyanate-terminated polyurethane prepolymer has an NCO group content of 1.8 to 4.0 wt%, based on the total weight of the isocyanate-terminated polyurethane prepolymer; an effective amount of a cross-linking agent, wherein the functionality of the cross-linking agent is 3; an effective amount of a catalyst; and a silane coupling agent, wherein the molar ratio of the silane coupling agent to the NCO group of the isocyanate-terminated polyurethane prepolymer is from 40: 100 to 120: 100.

Description

Technical Field

[0001] The present invention relates to a one-component (1K) polyurethane sealant composition and its use. More specifically, a one-component (1K) moisture-curable polyurethane sealant composition and its use as a sealant, a method for preparing the same, and an article comprising the cured one-component (1K) moisture-curable polyurethane sealant composition as a sealant. Background Art

[0002] Polyurethane sealant compositions typically include at least one urethane prepolymer. Such polyurethane sealants are typically prepared to have isocyanate end groups. Upon exposure to atmospheric moisture, the isocyanate groups react with water to form amino groups with the evolution of carbon dioxide. The amino groups so formed further react with available isocyanate groups to form urea bonds, thereby achieving curing of the polymer in the sealant and bonding to the material to be adhered. The sealant can be used to bond to non-porous substrates such as glass, ceramics, and metals.

[0003] It is well known that moisture-curable polyurethane sealant systems have several advantages. However, when such sealants are used to bond inorganic substrates, especially metal substrates, the sealants always fail in adhesion after water spray aging. Summary of the invention

[0004] The present invention provides a one-component (1K) moisture-curable polyurethane sealant composition that can be used as a sealant on metal substrates, particularly steel metal or tin substrates, with improved adhesion, corrosion resistance and water spray aging resistance. The polyurethane sealant of the present invention can be cured at room temperature and has no harmful solvents and low VOC emissions. The present invention provides an effective method for bonding polyurethane sealants to inorganic surfaces (steel metal or tin) without pretreatment.

[0005] In one aspect of the present invention, the one-component moisture-curable polyurethane sealant composition comprises: an isocyanate-terminated polyurethane prepolymer, wherein the NCO group content of the isocyanate-terminated polyurethane prepolymer is 1.8-4.0 wt% based on the total weight of the isocyanate-terminated polyurethane prepolymer; an effective amount of a crosslinking agent, wherein the functionality of the crosslinking agent is 3; an effective amount of a catalyst; and a silane coupling agent, wherein the molar ratio of the -Si-OA group of the silane coupling agent to the NCO group of the isocyanate-terminated polyurethane prepolymer is 40:100 to 120:100, and the silane coupling agent is represented by the following formula:

[0006]

[0007] Among them, independently,

[0008] 1 A. 2A may be the same or different and each is a C1-C10 straight chain or branched, aliphatic or alicyclic or substituted alicyclic or aromatic hydrocarbon,

[0009] 3 A is a linear or branched, aliphatic or alicyclic or substituted alicyclic or aromatic divalent hydrocarbon residue having 1 to 20 carbon atoms,

[0010] 4 A. 5 A may be the same or different and each represents a straight or branched alkyl group having 1 to 5 carbon atoms,

[0011] n is an integer from 0 to 2.

[0012] In another aspect, the present invention provides an article comprising a sealant on a surface thereof, wherein the sealant is a cured product of the composition of the present invention.

[0013] In another aspect, the present invention provides a method for sealing a substrate, the method comprising applying the one-component moisture-curable polyurethane sealant composition of the present invention to at least one surface of an article, and then curing the one-component moisture-curable polyurethane sealant composition on the surface.

[0014] Other objects and advantages of the invention will be apparent from the following detailed description and examples of the presently preferred embodiments. DETAILED DESCRIPTION

[0015] The present invention is described in more detail in the following paragraphs. Each aspect described in this way can be combined with any other one or more aspects, unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous can be combined with any other one or more features indicated as being preferred or advantageous.

[0016] In the context of the present invention, unless the context requires otherwise, the terms used should be interpreted according to the following definitions.

[0017] As used herein, the singular forms "a," "an," and "the" include both singular and plural referents unless the context clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and / or" unless the content clearly dictates otherwise.

[0018] As used herein, the term "comprising" is synonymous with "including" or "containing" and is inclusive or open-ended and does not exclude additional, unrecited members, elements, or method steps.

[0019] Unless otherwise specified, the recitation of numerical endpoints includes all numbers and fractions within the corresponding range as well as the recited endpoint.

[0020] If not expressly stated otherwise, all percentages given herein with respect to compositions or preparations relate to % by weight relative to the total weight of the respective composition or preparation.

[0021] Unless otherwise defined, all terms used in the present invention, including technical and scientific terms, have the meanings commonly understood by ordinary technicians in the field to which the present invention belongs. By further guidance, term definitions are used to better understand the teachings of the present invention.

[0022] The sealant of the present invention is a one-component moisture-curable material. As used herein, "one-component" means that all components of the sealant (except H2O supplied during the moisture-curing process) are formed into a single blended material. The term "moisture-curable" means that the sealant can be cured by a mechanism that at least partially includes water reacting with one or more components of the sealant. Specifically, moisture curing involves i) the reaction of water with the isocyanate groups of the prepolymer, ii) the reaction of water with a silane coupling agent to produce amino groups, which further catalyzes the reaction of water with the isocyanate groups of the prepolymer, iii) both i and ii, and ii is preferentially promoted, or iv) ii then i.

[0023] As used herein, "Mw" refers to the weight average molecular weight and refers to the theoretical value determined by gel permeation chromatography (GPC) relative to a linear polystyrene standard of 1.1 M to 580 Da, which can be measured using a Waters 2695 Separations Module with a Waters 2414 differential refractometer (RI detector). "Mn" refers to the number average molecular weight and also refers to the theoretical value determined by gel permeation chromatography (GPC).

[0024] As used herein, the glass transition temperature (Tg) or melting point of a particular polymer is determined according to DIN 53 765 using DSC.

[0025] The term "NCO content" refers to the content of isocyanate groups expressed in % by weight.

[0026] The term "curing" means exposing to any form of radiation, heating, or allowing to undergo a physical or chemical reaction that results in hardening or an increase in viscosity.

[0027] Surprisingly, it was found that the object of the present invention is solved by a polyurethane sealant composition comprising a cured product obtained from a one-component (1K) moisture-curable polyurethane sealant composition. The one-component (1K) moisture-curable polyurethane sealant composition comprises an isocyanate-terminated polyurethane prepolymer, an effective amount of a crosslinking agent, an effective amount of a catalyst, and a specific silane coupling agent, wherein the molar ratio of the silane coupling agent to the isocyanate-terminated polyurethane prepolymer is within a certain range.

[0028] Isocyanate-terminated polyurethane prepolymers

[0029] The isocyanate-terminated polyurethane prepolymer of the present invention is obtained by reacting at least one monomeric aromatic diisocyanate with a polyol having an average OH functionality of 2 to 3 and an OH number of 20 to 100 mg KOH / g. The NCO content of the isocyanate-terminated polyurethane prepolymer is 1.8% to 4.0% by weight, or 2.0% to 4.0% by weight, or 2.0% to 3.5% by weight, or 2.5% to 4.0% by weight, or 2.5% to 3.5% by weight.

[0030] In this reaction, any known catalyst may be used, such as dibutyltin dilaurate, stannous octoate, triethylenediamine, lead octoate, bis(dimethylamino)ethyl ether, etc. The catalyst is present in a concentration of about 0.001 wt % to about 1.0 wt %. Conventional catalytic amounts are used.

[0031] In this reaction, an excess of monomeric aromatic diisocyanate is used so that the resulting prepolymer has isocyanate end groups.

[0032] Preferably, the prepolymer of the present invention has an average molecular weight Mn of 5,000 to 15,000 g / mol, the average molecular weight Mn being determined by gel permeation chromatography (GPC) with tetrahydrofuran as mobile phase, a refractive index detector and an evaluation of 200 g / mol relative to polystyrene standards. More preferably, the average molecular weight is 5500 to 12000 g / mol, in particular 6000 to 10000 g / mol.

[0033] Suitable monomeric aromatic diisocyanates are in particular diphenylmethane 4,4'-diisocyanate, which optionally contains a portion of diphenylmethane 2,4'- and / or 2,2'-diisocyanate (MDI); toluene 2,4-diisocyanate or a mixture thereof with toluene 2,6-diisocyanate (TDI), phenylene 1,4-diisocyanate (PDI), 2,3,5,6-tetramethyl-1,4-diisocyanatobenzene, naphthalene 1,5-diisocyanate (NDI) or 3,3'-dimethylbiphenyl-4,4'-diisocyanate (TODI). Among them, diphenylmethane 4,4'-diisocyanate or toluene 2,4-diisocyanate or phenylene 1,4-diisocyanate is preferred.

[0034] A particularly preferred monomeric aromatic diisocyanate is diphenylmethane 4,4'-diisocyanate (4,4'-MDI). This 4,4'-MDI is a mass containing only small fractions of diphenylmethane 2,4'- and / or 2,2'-diisocyanate and is solid at room temperature.

[0035] Commercially available diphenylmethane 4,4′-diisocyanate of this quality is, for example, Desmodur 44MC (from Covestro) or Lupranat MRSS oder ME (from BASF) or Suprasec 1400 (from Huntsman).

[0036] Suitable polyols are especially polyether polyols. In some embodiments, a certain amount of optional polyester polyols are used together with polyether polyols. The repeating units present in the polyether polyols are preferably 1,2-ethyleneoxy, 1,2-propyleneoxy, 1,3-propyleneoxy, 1,2-butyleneoxy or 1,4-butyleneoxy. Preferably 1,2-ethyleneoxy and / or 1,2-propyleneoxy. More preferably, the repeating units present in the polyether polyols are mainly or exclusively 1,2-propyleneoxy. More particularly, based on all repeating units, the polyether polyols have 80% to 100% by weight of 1,2-propyleneoxy and 0% to 20% by weight of 1,2-ethyleneoxy. Most preferably, based on all repeating units, the polyether polyols have 80% to 90% by weight of 1,2-propyleneoxy and 10% to 20% by weight of 1,2-ethyleneoxy. The 1,2-propyleneoxy and 1,2-ethyleneoxy groups here each form, in particular, uniform blocks, with the poly(1,2-ethyleneoxy) blocks being at the chain ends.

[0037] The polyether polyol preferably has an OH number of 20 to 100 mg KOH / g, 80 to 90% by weight of 1,2-propyleneoxy groups and 10 to 20% by weight of 1,2-ethyleneoxy groups, based on all repeating units.

[0038] The polyether polyols preferably have an average molecular weight Mn of 4,000 to 8,500 g / mol, in particular 5,200 to 7,500 g / mol.

[0039] Such polyether polyols are commercially available, for example Caradol ET28-03 (from Shell), Desmophen 5031 BT (from Covestro) or Voranol 5815 (from Dow).

[0040] The raw material of the isocyanate-terminated polyurethane prepolymer may further include an optional polyester polyol. The polyester polyol includes a lactone polyol prepared by polymerization of a lactone, a compound such as castor oil, and a polyester polyol formed by the reaction of an alkylene glycol with a dicarboxylic acid.

[0041] In some embodiments of the present invention, the one-component polyurethane sealant composition includes 10 to 60 parts by weight, or 20 to 50 parts by weight, or 30 to 50 parts by weight of the isocyanate-terminated polyurethane prepolymer.

[0042] This prepolymer cooperates with the other components of the present invention to provide a one-component polyurethane sealant composition having a particularly attractive combination of low cure temperature, long open time combined with rapid cure, good adhesion after water spray aging, and good corrosion resistance.

[0043] Crosslinking agent

[0044] Crosslinkers (also referred to as "crosslinkers") suitable for use in the context of the present invention are known in the art and may include, for example, compounds containing at least three NCO groups, preferably three NCO groups. Modified polyurethane polymers having NCO groups at the terminals and optionally also within the chain are preferred.

[0045] The crosslinking agent is substantially free of organic polyamines, such as primary or secondary diamines or triamines. The polyamine may be any known aliphatic or aromatic polyamine, such as ethylenediamine, diethylenetriamine, propylenediamine, hexamethylenediamine, methylenebis(aniline), toluenediamine, isophoronediamine, trimethylpentanediamine, aniline-formaldehyde adduct polyamines, etc. Such organic polyamines have adverse effects on storage stability and other desired properties.

[0046] As previously mentioned, suitable crosslinking agents are optionally 0.5 to 15 wt%, or 1 to 15 wt%, or 5 to 15 wt% of an aliphatic isocyanate crosslinker, based on the total weight of the sealant composition. The aliphatic isocyanate crosslinker may be an aliphatic diisocyanate, such as hexamethylene diisocyanate (HDI); a trimer of such a diisocyanate; an aliphatic triisocyanate; and polymers derived from these homo- or co-monomers, or from the addition of a polyol or polyamine to one or more of these monomers, wherein the polyol or polyamine may be a polyether, polyester, polycarbonate, or polyacrylate. In some embodiments of the present invention, the aliphatic isocyanate crosslinker has an NCO functionality equal to or greater than 3.

[0047] The amount of crosslinking agent used is an amount sufficient to react with all isocyanate end groups and effect photocrosslinking. The desired concentration of crosslinking agent is one in which the equivalents of reactive crosslinking groups in the crosslinking agent used equal the number of equivalents of isocyanate groups present in the prepolymer. The amount should be sufficient to react with all isocyanate groups and crosslink the polymer, but the amount should not be such that the isocyanate groups are blocked rather than crosslinked.

[0048] Silane coupling agent

[0049] The silane coupling agent of the present invention can be commercially available or prepared by a known method.

[0050] In some embodiments, the silane coupling agent has the formula:

[0051]

[0052] Among them, independently,

[0053] 1 A. 2 A may be the same or different and each is a C1-C10 straight chain or branched, aliphatic or alicyclic or substituted alicyclic or aromatic hydrocarbon. Preferably, 1 A. 2 A is different and each is a C1-C6 straight or branched chain, aliphatic or alicyclic or substituted alicyclic or aromatic hydrocarbon group;

[0054] 3 A is a linear or branched, aliphatic or alicyclic or substituted alicyclic or aromatic divalent hydrocarbon residue having 1 to 20 carbon atoms, preferably 2 to 6 carbon atoms, more preferably -CH2-CH2- or -CH2-CH2-CH2-;

[0055] 4 A. 5 A may be the same or different and each represents a straight or branched chain alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, more preferably 4 A. 5 A each represents a methyl group, an ethyl group or an isopropyl group;

[0056] n is an integer from 0 to 2.

[0057] In some embodiments of the present invention, the silane coupling agent includes ((triethoxysilyl)propyl)methylisobutylimine, ((trimethoxysilyl)propyl)methylisobutylimine, ((methyldimethoxysilyl)propyl)methylisobutylimine, etc. In some embodiments of the present invention, the molar ratio of -Si-OA groups of the silane coupling agent to the NCO groups of the isocyanate-terminated polyurethane prepolymer is 40:100 to 120:100, preferably 42:100 to 108:100. When the contents of the silane coupling agent and the isocyanate-terminated polyurethane prepolymer are within the above range, the sealant has good water mist resistance.

[0058] In some preferred embodiments, the content of silane coupling agent also affects the degree of crosslinking. Moisture / water reacts preferentially with the silane coupling agent of the present invention rather than with the NCO group. Excess silane coupling agent produces an available amount of silane coupling agent containing primary amine groups, which promote or accelerate the curing reaction and then affect the crosslinking reaction. Therefore, the degree of crosslinking of the sealant is reduced, and the strength of the sealant is affected.

[0059] "Alkyl" as used in the context of the present invention relates to a straight or branched hydrocarbon group having 1 to 20 carbon atoms. As non-limiting examples thereof, mention may be made of methyl, ethyl, propyl, isopropyl, tert-butyl, n-pentyl and isopentyl.

[0060] Such silane coupling agents are commercially available, for example, KBE9103P from Shin-Etsu Chemical Co., Ltd., S340 from Chisso Corporation, Dynasylan VPS1262 from Evonik.

[0061] catalyst

[0062] The one-component polyurethane sealant composition optionally includes a catalyst.

[0063] Suitable catalysts are catalysts for accelerating the reaction of isocyanate groups and hydroxyl groups, in particular organotin(IV) compounds, such as, in particular, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, dibutyltin diacetylacetonate, dimethyltin dilaurate, dioctyltin diacetate, dioctyltin dilaurate or dioctyltin diacetylacetonate, complexes of bismuth(III) or zirconium(IV), in particular with a ligand selected from the group consisting of alkoxides, carboxylates, 1,3-diketonates, 8-hydroxyquinolinate salts, 1,3-ketoesters and 1,3-ketoamidates, or compounds containing tertiary amino groups, such as, in particular, 2,2′-dimorpholinodiethyl ether (DMDEE).

[0064] Commercially available products can be used in the present invention. Examples thereof include Dabco T 12 available from Evonik Specialty Chemicals (Shanghai).

[0065] Particularly preferably, the catalyst may be incorporated into the one-component polyurethane sealant composition in an amount of 0.1-0.5 wt %, preferably 0.15-0.3 wt %, for example 0.15 wt %, 0.25 wt %, 0.3 wt %, based on the total amount of the composition.

[0066] Other compounds

[0067] To formulate the sealant composition, the sealant composition of the present invention is combined with fillers and additives for sealant compositions known in the prior art. By adding such fillers / additives, physical properties such as rheological properties, viscosity, flow rate, sag, etc. can be modified to desired values. However, in order to prevent premature hydrolysis of moisture-sensitive groups of the polymer, such fillers / additives should be thoroughly dried before mixing with it.

[0068] If necessary, the polyurethane sealant composition of the present invention may contain various additives within the range not inhibiting the purpose of the present technology, such as fillers, plasticizers, anti-aging agents, antioxidants, pigments (dyes), thixotropic agents, ultraviolet absorbers, flame retardants, surfactants (including leveling agents), dispersants, dehydrating agents, adhesion promoters and antistatic agents.

[0069] <Packing>

[0070] Examples of fillers include any form of organic or inorganic fillers. Specific examples include hollow glass bubbles, fumed silica, calcined silica, precipitated silica, crushed silica, fused silica; diatomaceous earth; iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide; calcium carbonate, heavy calcium carbonate, precipitated calcium carbonate (light calcium carbonate), colloidal calcium carbonate, magnesium carbonate, zinc carbonate; pyrophyllite clay, kaolin clay, calcined clay; fatty acid treated products, resin acid treated products, urethane compound treated products, PVC powder and its fatty acid ester treated products, etc. One type of these may be used alone, or two or more types of these may be used in combination.

[0071] <Plasticizer>

[0072] Suitable plasticizers are well known in the art and include alkyl phthalates such as dioctyl phthalate or dibutyl phthalate, partially hydrogenated terpenes commercially available as "HB-40", and alkyl naphthalenes.

[0073] Specific examples of the plasticizer include diisononyl phthalate (DINP); dioctyl adipate, isodecyl succinate; diethylene glycol dibenzoate, pentaerythritol ester; butyl oleate, methyl acetylic ricinoleate; tricresyl phosphate, trioctyl phosphate; propylene glycol adipate polyester, butanediol adipate polyester, etc. One type of these may be used alone, or two or more types of these may be used in combination.

[0074] <Pigment>

[0075] Specific examples of the pigment include inorganic pigments such as titanium oxide, zinc oxide, ultramarine blue, iron oxide red, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochlorides and sulfates; and organic pigments such as azo pigments, phthalocyanine pigments, quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, anthrapyrimidine pigments, anthranthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, cyclic ketone pigments, dionepyrrolopyrrole pigments, quinonaphthalene pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindoline pigments and carbon black and the like.

[0076] Commercially available pigments include carbon blacks, for example titanium dioxide, such as those available from Multibis.

[0077] <Dewatering Agent>

[0078] Water scavengers are well known in the art and include tosyl isocyanate and other reactive isocyanates, molecular sieves, calcium oxide, procarbonate, silicates, etc. Oxazolides, imines and other water scavengers have a negative impact on the storage of one-component polyurethane compositions because they react with water to form amine compounds.

[0079] Particularly preferably, the water scavenger may be incorporated into the one-component polyurethane sealant composition in an amount of 0.05 to 4.0% by weight, based on the total amount of the polyurethane composition.

[0080] The one-component polyurethane sealant composition according to the present invention may optionally contain one or more other compounds, such as a plasticizer, a filler, a water scavenger, which may be combined as desired.

[0081] Method for preparing polyurethane sealant composition

[0082] A composition referred to as a "one-component" composition is one in which all of the ingredients of the composition are in the same container and are themselves storage-stable. The moisture-curable polyurethane composition is preferably a one-component composition. Given appropriate packaging and storage, it is typically storage-stable for several months, up to a year or more.

[0083] Upon application of the moisture-curable polyurethane sealant composition, the curing process begins. This produces a cured sealant composition.

[0084] The present invention also provides a sealing method, which comprises the following steps:

[0085] 1) applying the one-component moisture-curable polyurethane sealant composition of the present invention to a first substrate,

[0086] 2) optionally contacting the composition with a second substrate during the open time of the composition,

[0087] 3) Curing the composition by contact with moisture.

[0088] The sealant composition can be applied to the substrate by all known techniques.Before applying the one-component moisture-curable polyurethane sealant composition of the invention to the substrate, no additional pretreatment of the substrate surface, such as application of a primer coating on the surface, is required.

[0089] The moisture required for the curing of the moisture-curable polyurethane sealant composition preferably enters the composition by diffusion from the air (atmospheric moisture). In this process, a solid layer of the cured composition is formed on the surface of the composition in contact with the air ("skin"). Curing continues in the direction of diffusion from the outside to the inside, and the skin becomes thicker and thicker and eventually surrounds the entire composition applied. The moisture on one or more substrates preferentially reacts with the silane coupling agent of the present invention and produces ketones and amines. The ketone is essentially non-volatile at the operating temperature / curing temperature; therefore, the ketone will remain in the cured sealant composition for the most part to reduce the viscosity of the composition, improve the wettability of the plastic substrate, and enhance adhesion. Good adhesion can be achieved on metal substrates at operating temperatures / curing temperatures above the boiling point of the ketone.

[0090] The moisture-curable polyurethane sealant composition is preferably applied at ambient temperature, particularly at a temperature of about -10 to 50°C, preferably -5 to 45°C, particularly 0 to 40°C.

[0091] The moisture-curable polyurethane sealant composition preferably also cures at ambient temperature.

[0092] The substrate is preferably an inorganic substrate, including glass, ceramic, metal, etc. Metals include carbon steel, galvanized steel, stainless steel, tin plate. The substrate of the present invention may also include a plastic substrate such as polycarbonate; a powder-coated substrate such as a substrate treated with automotive electrophoretic paint. A particularly suitable substrate is bare metal.

[0093] "Cure rate" refers to the extent of polymer formation in a sealant composition within a given time after application, particularly by determining the thickness of the skin formed.

[0094] Moisture-curing polyurethane compositions are particularly suitable as sealants for elastic sealing of all kinds of joints, seams or cavities, in particular joints in structures, such as expansion joints or connection joints between structural parts or floor joints in civil engineering. Sealants with flexibility and high cold flexibility are particularly suitable for sealing expansion joints in interior structures.

[0095] It is to be understood that all embodiments disclosed herein with respect to the methods apply analogously to the disclosed dispersions, compositions and uses, and vice versa.

[0096] List of implementation plans

[0097] 1. A one-component polyurethane sealant composition comprising:

[0098] a) an isocyanate-terminated polyurethane prepolymer, wherein the NCO group content of the isocyanate-terminated polyurethane prepolymer is 1.8-4.0 wt % based on the total weight of the isocyanate-terminated polyurethane prepolymer,

[0099] b) an effective amount of a cross-linking agent, wherein the functionality of the cross-linking agent is 3,

[0100] c) an effective amount of a catalyst, and

[0101] d) a silane coupling agent, wherein the molar ratio of the -Si-OA group of the silane coupling agent to the NCO group of the isocyanate-terminated polyurethane prepolymer is 40:100 to 120:100, and the silane coupling agent is represented by the following formula:

[0102]

[0103] Among them, independently,

[0104] 1 A. 2 A may be the same or different and each is a C1-C10 straight chain or branched, aliphatic or alicyclic or substituted alicyclic or aromatic hydrocarbon,

[0105] 3 A is a linear or branched, aliphatic or alicyclic or substituted alicyclic or aromatic divalent hydrocarbon residue having 1 to 20 carbon atoms,

[0106] 4 A. 5 A may be the same or different and each represents a straight or branched alkyl group having 1 to 5 carbon atoms,

[0107] n is an integer from 0 to 2.

[0108] 2. The composition according to embodiment 1, wherein the silane coupling agent is represented by the following formula:

[0109]

[0110] Among them, independently,

[0111] 1 A. 2 A is each a C1-C6 straight chain or branched, aliphatic or alicyclic or substituted alicyclic or aromatic hydrocarbon group,

[0112] 3 A is a straight-chain aliphatic alkylene group having 2 to 6 carbon atoms,

[0113] 4 A. 5 A each represents a straight or branched alkyl group having 1 to 3 carbon atoms,

[0114] n is an integer from 0 to 2.

[0115] 3. The composition according to any one of the preceding embodiments, wherein the silane coupling agent is represented by the following formula:

[0116]

[0117] Among them, independently,

[0118] 1 A. 2 A is each a C1-C6 straight chain or branched, aliphatic or alicyclic or substituted alicyclic or aromatic hydrocarbon,

[0119] 3 A is -CH2-CH2- or -CH2-CH2-CH2-,

[0120] 4 A. 5 A each represents a methyl group, an ethyl group or an isopropyl group,

[0121] n is an integer from 0 to 1.

[0122] 4. The composition according to any one of the preceding embodiments, wherein the NCO group content of the isocyanate-terminated polyurethane prepolymer is 2.0 to 3.5 wt %, based on the total weight of the isocyanate-terminated polyurethane prepolymer.

[0123] 5. The composition according to any one of the preceding embodiments, wherein the molar ratio of -Si-OA groups of the silane coupling agent to NCO groups of the isocyanate-terminated polyurethane prepolymer is from 42:100 to 108:100.

[0124] 6. The composition according to any one of the preceding embodiments, wherein the content of the silane coupling agent is 1.3-2.7 parts by weight.

[0125] 7. The composition according to any one of the preceding embodiments, wherein the content of the silane coupling agent is 1.5-2.5 parts by weight.

[0126] 8. The composition according to any one of the preceding embodiments, wherein the composition comprises 10 to 60 parts by weight of an isocyanate-terminated polyurethane prepolymer.

[0127] 9. The composition according to any of the preceding embodiments, wherein the catalyst is selected from platinum, palladium, rhodium, nickel, iridium, ruthenium catalysts and mixtures thereof.

[0128] 10. The composition according to any one of the preceding embodiments, wherein the composition comprises 0.05 wt% to 4.0 wt% of a water scavenger, based on the total weight of the composition.

[0129] 11. The composition according to embodiment 10, wherein the water scavenger comprises reactive isocyanate, molecular sieves, calcium oxide, orthoformate, silicate.

[0130] 12. The composition according to any one of the preceding embodiments, wherein the composition comprises 10 to 40 parts by weight of a plasticizer.

[0131] 13. The composition according to any one of the preceding embodiments, wherein the composition comprises 10 to 40 parts by weight of filler.

[0132] 14. The composition according to embodiment 13, wherein the filler comprises calcium carbonate, carbon black, alumina, kaolin, PVC powder, silicate or hollow glass microspheres, mica powder, attapulgite and mixtures thereof.

[0133] 15. An article comprising a sealant on a surface thereof, wherein the sealant is a cured product of the composition according to any one of the preceding embodiments.

[0134] 16. A method of using a one-component polyurethane sealant, comprising:

[0135] applying the one-component polyurethane sealant composition of at least one of embodiments 1 to 14 to the surface of an article, and

[0136] The one-component polyurethane sealant composition in contact with the surface is cured to prepare a sealant.

[0137] Example:

[0138] The present invention will be further described and illustrated in detail with reference to the following examples. These examples are intended to help those skilled in the art to better understand and practice the present invention, but are not intended to limit the scope of the invention. All numerals in the examples are based on weight, unless otherwise indicated.

[0139] raw material

[0140]

[0141]

[0142] *All raw materials were used directly without any special treatment.

[0143] <Preparation of isocyanate-terminated polyurethane prepolymer>

[0144] To synthesize P1, diisononyl phthalate (40 g) and Caradol ET28-03 (354.08 g) were added to the reactor. The system was then heated to 110°C under vacuum and stirred for 120 minutes. Thereafter, the reactor was cooled until the temperature dropped to 80°C, and Desmodur 44M liquid (45.92 g) and Additive TI (0.64 g) were added to the reactor. Then, after stirring for 60 minutes under vacuum, catalyst stannous octoate (0.008 g) and diisononyl phthalate (4 g) were added and stirred for 60 minutes under vacuum. The heater was then stopped and the reactor was cooled to 40°C to obtain the final prepolymer P1.

[0145] To synthesize P2, diisononyl phthalate (40 g) and Caradol ET28-03 (359.72 g) were added to the reactor. The system was then heated to 110°C under vacuum and stirred for 120 minutes. Thereafter, the reactor was cooled until the temperature dropped to 80°C, and Desmodur 44M liquid (40.28 g) and Additive TI (0.64 g) were added to the reactor. Then, after stirring under vacuum for 60 minutes, catalyst stannous octoate (0.008 g) and diisononyl phthalate (4 g) were added and stirred for 60 minutes under vacuum. The heater was then stopped and the reactor was cooled to 40°C to obtain the final prepolymer P2.

[0146] To synthesize P3, diisononyl phthalate (40 g) and Caradol ET28-03 (365.32 g) were added to the reactor. The system was then heated to 110°C under vacuum and stirred for 120 minutes. Thereafter, the reactor was cooled until the temperature dropped to 80°C, and Desmodur 44M liquid (34.68 g) and Additive TI (0.64 g) were added to the reactor. Then, after stirring under vacuum for 60 minutes, catalyst stannous octoate (0.008 g) and diisononyl phthalate (4 g) were added and stirred for 60 minutes under vacuum. The heater was then stopped and the reactor was cooled to 40°C to obtain the final prepolymer P3.

[0147] To synthesize P4, diisononyl phthalate (40 g), Caradol ET28-03 (227.6 g) and Priplast 1838 (113.6 g) were added to the reactor. The system was then heated to 110°C under vacuum and stirred for 120 minutes. Thereafter, the reactor was cooled until the temperature dropped to 80°C, and Desmodur 44M liquid (58.8 g) and Additive TI (0.64 g) were added to the reactor. Then, after stirring for 60 minutes under vacuum, catalyst stannous octoate (0.008 g) and diisononyl phthalate (4 g) were added and stirred for 60 minutes under vacuum. The heater was then stopped and the reactor was cooled to 40°C to obtain the final prepolymer P4.

[0148] To synthesize P5, diisononyl phthalate (40 g) and Caradol ET28-03 (361.96 g) were added to the reactor. The system was then heated to 110°C under vacuum and stirred for 120 minutes. Thereafter, the reactor was cooled until the temperature dropped to 80°C, and Desmodur 44M liquid (38.04 g) and Additive TI (0.64 g) were added to the reactor. Then, after stirring under vacuum for 60 minutes, catalyst stannous octoate (0.008 g) and diisononyl phthalate (4 g) were added and stirred for 60 minutes under vacuum. The heater was then stopped and the reactor was cooled to 40°C to obtain the final prepolymer P5.

[0149] To synthesize P6, diisononyl phthalate (40 g) and Caradol ET28-03 (337.28 g) were added to the reactor. The system was then heated to 110°C under vacuum and stirred for 120 minutes. Thereafter, the reactor was cooled until the temperature dropped to 80°C, and Desmodur 44M liquid (62.72 g) and Additive TI (0.64 g) were added to the reactor. Then, after stirring under vacuum for 60 minutes, catalyst stannous octoate (0.008 g) and diisononyl phthalate (4 g) were added and stirred for 60 minutes under vacuum. The heater was then stopped and the reactor was cooled to 40°C to obtain the final prepolymer P6.

[0150] To synthesize P7, diisononyl phthalate (40 g) and Caradol ET28-03 (331.68 g) were added to the reactor. The system was then heated to 110°C under vacuum and stirred for 120 minutes. Thereafter, the reactor was cooled until the temperature dropped to 80°C, and Desmodur 44M liquid (68.32 g) and Additive TI (0.64 g) were added to the reactor. Then, after stirring for 60 minutes under vacuum, catalyst stannous octoate (0.008 g) and diisononyl phthalate (4 g) were added and stirred for 60 minutes under vacuum. The heater was then stopped and the reactor was cooled to 40°C to obtain the final prepolymer P7.

[0151] To synthesize P8, diisononyl phthalate (40 g) and Caradol ET28-03 (326.08 g) were added to the reactor. The system was then heated to 110°C under vacuum and stirred for 120 minutes. Thereafter, the reactor was cooled until the temperature dropped to 80°C, and Desmodur 44M liquid (73.92 g) and Additive TI (0.64 g) were added to the reactor. Then, after stirring for 60 minutes under vacuum, catalyst stannous octoate (0.008 g) and diisononyl phthalate (4 g) were added and stirred for 60 minutes under vacuum. The heater was then stopped and the reactor was cooled to 40°C to obtain the final prepolymer P8.

[0152] To synthesize P9, diisononyl phthalate (40 g) and Caradol ET28-03 (313.6 g) were added to the reactor. The system was then heated to 110°C under vacuum and stirred for 120 minutes. Thereafter, the reactor was cooled until the temperature dropped to 80°C, and Desmodur 44M liquid (46 g) and Additive TI (0.64 g) were added to the reactor. Then, after stirring under vacuum for 60 minutes, catalyst stannous octoate (0.008 g) and diisononyl phthalate (4 g) were added and stirred for 60 minutes under vacuum. The heater was then stopped and the reactor was cooled to 40°C to obtain the final prepolymer P9.

[0153] <Preparation of One-Component Polyurethane Sealant Composition>

[0154] Example 1

[0155] To prepare the curable one-component polyurethane sealant composition E1, Mesamoll (14 g), Omya-2-QY (20 g), BLH (10 g), P1 (40 g), Desmodur N 100 (1.25 g) and Additive TI (0.082 g) were added to a container and mixed by Speedmixer at 1000 rpm for 1 minute. Then, TS 720 (2 g) was added to the system and mixed by Speedmixer at 1000 rpm for 1 minute, followed by Dynasylan VPS1262 (2 g) added and mixed by Speedmixer at 1000 rpm for 30 seconds and at 1750 rpm for 60 seconds, requiring vacuum during mixing.

[0156] Example 2

[0157] To prepare the curable one-component polyurethane sealant composition E2, Mesamoll (14 g), Omya-2-QY (20 g), BLH (10 g), P9 (40 g), Desmodur N 100 (1.25 g) and Additive TI (0.082 g) were added to a container and mixed by Speedmixer at 1000 rpm for 1 minute. Then, TS 720 (2 g) was added to the system and mixed by Speedmixer at 1000 rpm for 1 minute, followed by Dynasylan VPS1262 (2 g) added and mixed by Speedmixer at 1000 rpm for 30 seconds and at 1750 rpm for 60 seconds, requiring vacuum during mixing.

[0158] Example 3

[0159] To prepare the curable one-component polyurethane sealant composition E3, Mesamoll (14 g), Omya-2-QY (20 g), BLH (10 g), P4 (40 g), Desmodur N 100 (1.25 g) and Additive TI (0.082 g) were added to a container and mixed by Speedmixer at 1000 rpm for 1 minute. Then, TS 720 (2 g) was added to the system and mixed by Speedmixer at 1000 rpm for 1 minute, followed by Dynasylan VPS1262 (2 g) added and mixed by Speedmixer at 1000 rpm for 30 seconds and at 1750 rpm for 60 seconds, requiring vacuum during mixing.

[0160] Example 4

[0161] To prepare the curable one-component polyurethane sealant composition E4, Mesamoll (14 g), Omya-2-QY (20 g), BLH (10 g), P6 (40 g), Desmodur N 100 (1.25 g) and Additive TI (0.082 g) were added to a container and mixed by Speedmixer at 1000 rpm for 1 minute. Then, TS 720 (2 g) was added to the system and mixed by Speedmixer at 1000 rpm for 1 minute, followed by Dynasylan VPS1262 (2 g) added and mixed by Speedmixer at 1000 rpm for 30 seconds and at 1750 rpm for 60 seconds, requiring vacuum during mixing.

[0162] Example 5

[0163] To prepare the curable one-component polyurethane sealant composition E5, Mesamoll (14 g), Omya-2-QY (20 g), BLH (10 g), P7 (40 g), Desmodur N 100 (1.25 g) and Additive TI (0.082 g) were added to a container and mixed by Speedmixer at 1000 rpm for 1 minute. Then, TS 720 (2 g) was added to the system and mixed by Speedmixer at 1000 rpm for 1 minute, followed by Dynasylan VPS1262 (2 g) added and mixed by Speedmixer at 1000 rpm for 30 seconds and at 1750 rpm for 60 seconds, requiring vacuum during mixing.

[0164] Comparative Example 1

[0165] To prepare the curable one-component polyurethane sealant composition CE1, Mesamoll (14 g), Omya-2-QY (20 g), BLH (10 g), P3 (40 g), Desmodur N 100 (1.25 g) and Additive TI (0.082 g) were added to a container and mixed by Speedmixer at 1000 rpm for 1 minute. Then, TS 720 (2 g) was added to the system and mixed by Speedmixer at 1000 rpm for 1 minute, followed by Dynasylan VPS1262 (2 g) added and mixed by Speedmixer at 1000 rpm for 30 seconds and at 1750 rpm for 60 seconds, requiring vacuum during mixing.

[0166] Comparative Example 2

[0167] To prepare the curable one-component polyurethane sealant composition CE2, Mesamoll (14 g), Omya-2-QY (20 g), BLH (10 g), P5 (40 g), Desmodur N 100 (1.25 g) and Additive TI (0.082 g) were added to a container and mixed by Speedmixer at 1000 rpm for 1 minute. Then, TS 720 (2 g) was added to the system and mixed by Speedmixer at 1000 rpm for 1 minute, followed by Dynasylan VPS1262 (2 g) added and mixed by Speedmixer at 1000 rpm for 30 seconds and at 1750 rpm for 60 seconds, requiring vacuum during mixing.

[0168] Comparative Example 3

[0169] To prepare the curable one-component polyurethane sealant composition CE3, Mesamoll (14 g), Omya-2-QY (20 g), BLH (10 g), P2 (40 g), Desmodur N 100 (1.25 g) and Additive TI (0.082 g) were added to a container and mixed by Speedmixer at 1000 rpm for 1 minute. Then, TS 720 (2 g) was added to the system and mixed by Speedmixer at 1000 rpm for 1 minute, followed by Dynasylan VPS1262 (2 g) added and mixed by Speedmixer at 1000 rpm for 30 seconds and at 1750 rpm for 60 seconds, requiring vacuum during mixing.

[0170] Comparative Example 4

[0171] To prepare the curable one-component polyurethane sealant composition CE4, Mesamoll (14 g), Omya-2-QY (20 g), BLH (10 g), P8 (40 g), Desmodur N 100 (1.25 g) and Additive TI (0.082 g) were added to a container and mixed by Speedmixer at 1000 rpm for 1 minute. Then, TS 720 (2 g) was added to the system and mixed by Speedmixer at 1000 rpm for 1 minute, followed by Dynasylan VPS1262 (2 g) added and mixed by Speedmixer at 1000 rpm for 30 seconds and at 1750 rpm for 60 seconds, requiring vacuum during mixing.

[0172] Examples 6-9 and CE4-CE8

[0173] The curable one-component polyurethane sealant compositions of E6 to E10, CE4 to CE11 were prepared with reference to Examples 1 to 4. The curable one-component polyurethane sealant compositions of E6 to E10 and CE4 to CE11 were cured with reference to Examples 1 to 4. More details are listed in the Results section below.

[0174] <Curing of Curable One-Component Polyurethane Sealant Composition>

[0175] All sample / sealant assemblies were cured at room temperature (25 ± 2°C) and 50% humidity.

[0176] Various tests were performed on the cured sealant samples.

[0177] The following examples are given to illustrate the present invention. Because these examples are given for the purpose of illustration only, the present invention should not be construed as being limited thereto.

[0178] Test Method

[0179] Sample preparation

[0180] The substrate (tinplate, RS14 steel plate) was cleaned with ethyl acetate and then conditioned for a few minutes under ambient conditions to ensure that the surface was completely dry. The sealant composition of about 10 mm in diameter was applied by using a circular nozzle. The nozzle was held at an angle of about 45° and the sealant composition was applied until the backstroke of the sealant composition was felt and the nozzle began to slide slightly above the surface (the nozzle should not scratch or contaminate the substrate surface). An attempt was made to obtain uniform beads of 12-15 mm in width and about half the width in height. The sealant composition was cured for about 7 days at a constant temperature and humidity (23°C, 50% relative humidity).

[0181] <Knife bead adhesion test>

[0182] The knife bead adhesion test covers sealant determination on tinplate substrates and carbon steel substrates.

[0183] After curing, the scraping step is performed by cutting the leading edge of the bead to form a loose pull ring of about 25 ± 5 mm in length to be fixed in a clamping tool such as a vise. The loose pull ring is then clamped with the clamping tool to pull back the bead itself. While pulling, a 45° angle relative to the oily rolled steel test plate is cut with a knife every 6 ± 2 mm of the bead. The test process is as follows Figure 1 shown.

[0184] Adhesion evaluation:

[0185] The failure modes of the sealant include adhesive failure (AF) and cohesive failure (CF).

[0186] Adhesive failure (AF) refers to the bond failure at the interface between the sealant and the substrate. Cohesive failure (CF) refers to the bond failure within the sealant layer.

[0187] Compared with adhesive failure (AF), cohesive failure (CF) indicates a more stable bond and a better bonding effect.

[0188] The evaluation report of the amount of cohesive failure (CF) is the percentage of the area. The degree of failure is expressed as the percentage (%) of the test area for each current failure mode. Generally, cohesive failure is divided into three groups.

[0189] Cohesion rating scale:

[0190] Excellent: 95% to 100%, CF;

[0191] Good: 75% to 95%, CF;

[0192] Pass: equal to or greater than 70%, CF;

[0193] Fail: less than 70%, CF.

[0194] If the cohesive failure is large, that is, the cohesive failure is equal to or greater than 70%, the composition is considered to pass the knife bead adhesion test.

[0195] <Cataplasma Storage Test>

[0196] The Cataplasma storage test is an accelerated aging test in which the cured sealant on the test panel is exposed to 70 °C and 100% relative humidity for 7 days, and then exposed to -20 °C for at least 16 hours.

[0197] After Cataplasma storage, the knife bead adhesion test is performed and the adhesion grade is given as described above.

[0198] <Appearance (Bubble Inspection)>

[0199] After curing, the sealant sample is cut and the inside of the sealant is checked for bubbles.

[0200] The appearance test results are recorded and graded as follows:

[0201] - Fail: there are bubbles;

[0202] - Pass: there are no bubbles.

[0203] Results

[0204] Table 1.

[0205]

[0206]

[0207] Table 1 shows the compositions of different isocyanate-terminated polyurethane prepolymers (P1-P9).

[0208] Table 2.

[0209]

[0210] Table 2 shows the compositions of the one-component moisture-curable polyurethane sealant compositions E1-E5 and CE1-CE4.

[0211] Table 3.

[0212]

[0213]

[0214] Table 3 shows the test results of the one-component moisture-curable polyurethane sealant compositions E1-E5 and CE1-CE4.

[0215] It can be seen that the polyurethane sealants of E1 to E5 provide good adhesion on the steel metal surface and the tin surface without any dehydration pretreatment of their surfaces. In addition, the polyurethane sealants of E1 to E5 provide good adhesion after the Cataplasma storage test.

[0216] Table 4.

[0217]

[0218] Table 4 shows the compositions of moisture-curable polyurethane sealant compositions E6-E9 and CE5-CE8.

[0219] Table 5.

[0220]

[0221] Table 5 shows the test results of moisture-curable polyurethane sealant compositions E6-E9 and CE5-CE8.

[0222] Table 6.

[0223]

[0224] Table 6 shows the compositions of moisture-curable polyurethane sealant compositions E10-E11 and CE9-CE12.

[0225] Table 7.

[0226]

[0227] Table 7 shows the test results of moisture-curable polyurethane sealant compositions E10-E11 and CE9-CE12.

Claims

1. A one-component polyurethane sealant composition comprising: e) an isocyanate-terminated polyurethane prepolymer, wherein the NCO group content of the isocyanate-terminated polyurethane prepolymer is 1.8-4.0 wt % based on the total weight of the isocyanate-terminated polyurethane prepolymer, f) an effective amount of a cross-linking agent, wherein the functionality of the cross-linking agent is 3, g) an effective amount of a catalyst, and h) a silane coupling agent, wherein the molar ratio of the -Si-OA group of the silane coupling agent to the NCO group of the isocyanate-terminated polyurethane prepolymer is 40:100 to 120:100, and the silane coupling agent is represented by the following formula: Among them, independently, 1 A. 2 A may be the same or different and each is a C1-C10 straight chain or branched, aliphatic or alicyclic or substituted alicyclic or aromatic hydrocarbon, 3 A is a linear or branched, aliphatic or alicyclic or substituted alicyclic or aromatic divalent hydrocarbon residue having 1 to 20 carbon atoms, 4 A. 5 A may be the same or different and each represents a straight or branched alkyl group having 1 to 5 carbon atoms, n is an integer from 0 to 2.

2. The composition according to claim 1, wherein the silane coupling agent is represented by the following formula: in, Independently, 1 A. 2 A is each a C1-C6 straight chain or branched, aliphatic or alicyclic or substituted alicyclic or aromatic hydrocarbon group, 3 A is a straight-chain aliphatic alkylene group having 2 to 6 carbon atoms, 4 A. 5 A each represents a straight or branched alkyl group having 1 to 3 carbon atoms, n is an integer from 0 to 2.

3. The composition according to claim 1, wherein the silane coupling agent is represented by the following formula: in, Independently, 1 A. 2 A is each a C1-C6 straight chain or branched, aliphatic or alicyclic or substituted alicyclic or aromatic hydrocarbon, 3 A is -CH2-CH2- or -CH2-CH2-CH2-, 4 A. 5 A each represents a methyl group, an ethyl group or an isopropyl group, n is an integer from 0 to 1.

4. The composition of claim 1, wherein the NCO group content of the isocyanate-terminated polyurethane prepolymer is 2.0 to 3.5 wt% based on the total weight of the isocyanate-terminated polyurethane prepolymer. 5 . The composition of claim 1 , wherein the molar ratio of the —Si—OA group of the silane coupling agent to the NCO group of the isocyanate-terminated polyurethane prepolymer is 42:100 to 108:

100. The composition according to claim 1 , wherein the content of the silane coupling agent is 1.3-2.7 parts by weight.

7. The composition according to claim 1, wherein the content of the silane coupling agent is 1.5-2.5 parts by weight.

8. The composition of claim 1, wherein the composition comprises 10 to 60 parts by weight of the isocyanate-terminated polyurethane prepolymer.

9. The composition of claim 1, wherein the catalyst is selected from the group consisting of platinum, palladium, rhodium, nickel, iridium, ruthenium catalysts and mixtures thereof.

10. The composition of claim 1, wherein the composition comprises 0.05 wt% to 4.0 wt% of the water scavenger based on the total weight of the composition.

11. The composition of claim 10, wherein the water scavenger comprises reactive isocyanate, molecular sieve, calcium oxide, orthoformate, silicate.

12. The composition according to claim 1, wherein the composition comprises 10 to 40 parts by weight of a plasticizer.

13. The composition of claim 1, wherein the composition comprises 10 to 40 parts by weight of a filler.

14. The composition according to claim 13, wherein the filler comprises calcium carbonate, carbon black, alumina, kaolin, PVC powder, silicate or hollow glass microspheres, mica powder, attapulgite and mixtures thereof.

15. An article comprising a sealant on a surface thereof, wherein the sealant is a cured product of the composition according to any one of claims 1 to 14.

16. A method of using a one-component polyurethane sealant, the method comprising: applying the one-component polyurethane sealant composition according to any one of claims 1 to 14 to the surface of an article, and The one-component polyurethane sealant composition in contact with the surface is cured to prepare a sealant.

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