EP4649120A1

EP4649120A1 - Adhesive compositions for low energy surfaces and adhesives therefrom

Info

Publication number: EP4649120A1
Application number: EP23915344.8A
Authority: EP
Inventors: Wenyan SUN; Hongyu CHU; Daoqiang Lu
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 2023-01-12
Filing date: 2023-01-12
Publication date: 2025-11-19
Also published as: WO2024148574A1; TW202436578A; CN120530175A

Abstract

This invention relates to an adhesive composition which is advantageously employed to improve the bonding of various of low energy substrates such as rubber-based substrates. The adhesive composition comprises silicone, fillers, and specific adhesion promoters, along with related method of using the same. The adhesive compositions could be used as adhesives after curing, for example, in automotive industrial loudspeaker applications, which provides very good bonding strength on various low energy surfaces.

Description

ADHESIVE COMPOSITIONS FOR LOW ENERGY SURFACES AND ADHESIVES THEREFROM

Technical field

The present disclosure relates to adhesive compositions for low energy surface bonding, adhesives therefrom, especially moisture-curable adhesive compositions and adhesives therefrom, along with related methods of using the same. The adhesive compositions and adhesives can be used, for example, in vehicle loudspeaker bonding applications.

Background of the invention

Low surface energy materials typically have surface energy values of less than 45 mJ/m², more typically less than 40 mJ/m², such as less than 35 mJ/m². Due to the outstanding physical properties, mechanical properties, especially good aging and high reliability performance, low surface energy materials, such as EPDM (ethylene propylene diene monomer compounded rubber) , SBR (styrene butadiene rubber) , IIR (isobutylene isoprene rubber) , TPU (thermal plastic polyurethane) are widely used in industry fields instead of some traditional materials with high surface energy.
It may though be desired to bond such materials together to obtain the characteristics of each material. Such low energy surfaces are well known to be difficult to bond to each other and to other surfaces using adhesive bonding technology since they have few active bonding sites available at the free surfaces.
Bonding low energy surfaces by surface pre-treatments such as flame treatments, plasma treatments, oxidation, sputter etching, corona discharge, or primer treatments with a high surface energy material is well known. Such treatments disrupt the bonds at the surface of the low energy material providing sites which are reactive, and which can participate in bonding reactions with adhesive materials. However, such surface pre-treatments are usually undesirable, in that they add cost to the process, they are not particularly reproducible in their results, and the effect of the pre-treatments wears off with time so the pre-treated surfaces must be re-pre-treated if they are not bonded within a reasonable period of time.
It is desired to develop adhesive compositions, which will bond low surface energy substrates without such surface pre-treatment.

Summary of the invention

It is therefore the object of the present invention to overcome the above-mentioned drawbacks by providing a high-performance adhesive composition which has excellent bonding performances on various low surface energy surfaces.
It has been surprisingly found that an adhesive prepared from a moisture curable adhesive composition comprising at least a silicone polymer or a silane modified polymer, a filler, an effective amount of catalyst, an amnio functional silane or amnio functional silane oligomer, the amnio functional silane or amnio functional silane oligomer having an amino functionality of equal to or greater than 1, an epoxy functional silane or epoxy functional silane oligomer, and the epoxy functional silane or epoxy functional silane oligomer having an epoxy functionality of equal to or greater than 1, a silane compound having the formula R-Si (R₁) ₃ (I) or its oligomer, each R₁ being independently selected from hydroxy, alkoxy, alkyl, sulfhydryl, halogen, epoxy group or amino group with the proviso that at least two R₁ are alkoxy, and R being an organic group containing alkyl, phenyl, alkenyl, alkynyl or acrylate group, and the silane compound having the formula (I) or its oligomer having an alkyl, phenyl, alkenyl, alkynyl or acrylate functionality of equal to or greater than 1, wherein the mole ratio of the amino group of amnio functional silane to the epoxy group of the epoxy functional silane/epoxy functional silane oligomer being 1.0: 1 to 2.95: 1, and the mole ratio of the alkyl, phenyl, alkenyl, alkynyl or acrylate group of the silane compound having the formula (I) or its oligomer to the epoxy group of the epoxy functional silane/epoxy functional silane oligomer being 0.65: 1 to 2.5: 1, provides very good bonding properties on various low surface energy surfaces.
According to one aspect, the present invention relates to a method of using an adhesive composition which comprises: applying an adhesive composition of present invention on a first substrate, attaching a second substrate to the first substrate to form an article, and curing the article.
According to one aspect, the present invention is directed to an adhesive comprising a cured product of the adhesive composition according to present invention.
According to still another aspect, the present invention also relates to an article comprising a first substrate, a second substrate and a cured adhesive composition disposed between and adhering the first substrate and the second substrate, wherein the cured adhesive composition is the cured product of the adhesive composition according to present invention.
In still another aspect, the present invention is directed to an automotive loudspeaker comprising an article of present invention.
The inventive adhesive compositions and adhesive systems are particularly well suited for bonding applications of various low energy surfaces, which involve at least one low energy surface, especially rubber-based surfaces, for example, EPDM (ethylene propylene diene monomer compounded rubber) and SBR (styrene butadiene rubber) .

Detailed description of the invention

In the following passages the present invention is described in more detail. Each aspect so described may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particularly, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.
In the context of the present invention, the terms used are to be construed in accordance with the following definitions, unless a context dictates otherwise.
As used herein, the singular forms “a” , “an” and “the” include both singular and plural referents unless the context clearly dictates otherwise. For example, reference to "a filler" encompasses embodiments having one, two or more fillers. 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.
The terms “comprising” , “comprises” and “comprised of” as used herein are synonymous with “including” , “includes” or “containing” , “contains” , and are inclusive or open-ended and do not exclude additional, non-recited members, elements or process steps.
The term “ambient temperature” refers to a temperature in the range of 20 ℃. to 25 ℃., inclusive.
The recitation of numerical end points includes all numbers and fractions subsumed within the respective ranges, as well as the recited end points.
Unless otherwise defined, all terms used in the disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of the ordinary skills in the art to which this invention belongs to. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.
In the context of this disclosure, several terms shall be utilized.
The terms “Polymer” is used herein consistent with its common usage in chemistry. Polymers are composed of many repeated subunits. The term “polymer” is used to describe the resultant material formed from a polymerization reaction.
As used herein, the term “Alkyl” refers to a monovalent linear, cyclic or branched moiety containing C1 to C24 carbon and only single bonds between carbon atoms in the moiety and including, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, heptyl, 2, 4, 4-trimethylpentyl, 2-ethylhexyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-hexadecyl, and n-octadecyl.
As used herein, the term “Aryl” refers to a monovalent unsaturated aromatic carbocyclic group of from 6 to 24 carbon atoms having a single ring (e.g., phenyl) or multiple condensed (fused) rings, wherein at least one ring is aromatic (e.g., naphthyl, dihydrophenanthrenyl, fluorenyl, or anthryl) . Preferred examples include phenyl, methyl phenyl, ethyl phenyl, methyl naphthyl, ethyl naphthyl, and the like.
As used herein, the term "Alkenyl" refers to an alkyl group, as defined herein, which consists of at least two carbon atoms and at least one carbon-carbon double bond, e.g., ethenyl, propenyl, butenyl, or pentenyl and structural isomers thereof such as 1-or 2-propenyl, 1-, 2-, or 3-butenyl, etc. Alkenyl groups can be substituted or unsubstituted. If they are substituted, the substituents are as defined above for alkyl. As used herein, the term “Alkenyloxy” refers to alkenyl-O-, wherein alkenyl is defined herein.
As used herein, the term "Alkynyl" refers to an alkyl group, as defined herein, which consists of at least two carbon atoms and at least one carbon-carbon triple bond, e.g., ethynyl (acetylene) , propynyl, butynyl, or petynyl and structural isomers thereof as described above. Alkynyl groups can be substituted or unsubstituted. If they are substituted, the substituents are as defined above for alkyl. "Alkylnyloxy" refers to an alkynyl group, as defined herein, that is linked via an -O-to the rest of the molecule.
As used herein, the term “Alkoxy” refers to the group -O-R, wherein R is alkyl as defined above.
As used herein, the above groups may be further substituted or unsubstituted. When substituted, hydrogen atoms on the groups are replaced by substituent group (s) that is one or more groups independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, heteroaralkyl, (heteroalicyclyl) alkyl, hydroxy, protected hydroxyl, alkoxy, aryloxy, acyl, ester, mercapto, alkylthio, arylthio, cyano, halogen, carbonyl, thiocarbonyl, O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl, C-amido, N-amido, S-sulfonamido, N-sulfonamido, C-carboxy, protected C-carboxy, O-carboxy, isocyanato, thiocyanato, isothiocyanato, nitro, silyl, sulfenyl, sulfinyl, sulfonyl, haloalkyl, haloalkoxy, trihalomethanesulfonyl, trihalomethanesulfonamido, and amino, including mono-and di-substituted amino groups, and the protected derivatives thereof. In case that an aryl is substituted, substituents on an aryl group may form a non-aromatic ring fused to the aryl group, including a cycloalkyl, cycloalkenyl, cycloalkynyl, and heterocyclyl.
The term, “Silicone polymers” herein refers to siloxane polymers, polyorganosiloxanes or polydiorganosiloxanes, such as polydimethylsiloxane (PDMS) .
As used herein, the term, “Moisture cure” herein refers to hardening or vulcanization of the curable portion of the material or polymer by condensation crosslinking reaction of terminal functional group of polymer chains, brought about by water or moisture in the air, in the presence of a moisture curing catalyst.
As discussed previously, embodiments of the present disclosure are directed to a moisture-curable adhesive composition comprising at least a silicone or a silane-modified polymer, a filler, an effective amount of catalyst, an amnio functional silane or amnio functional silane oligomer, an epoxy functional silane or epoxy functional silane oligomer, a silane compound R-Si (R₁) ₃ or its oligomer, each R₁ being independently selected from hydroxy, alkoxy, alkyl, sulfhydryl, halogen, epoxy group or amino group with the proviso that at least two R₁ are alkoxy, and R being an organic group containing alkyl, phenyl, alkenyl, alkynyl or acrylate group.
Silicone polymer or silane modified polymer
The moisture-curable adhesive composition comprises at least a silicone polymer or a silane modified polymer.
Suitable silicone polymer that can be used in the present invention may be any polymer that has a polysiloxane structure as a main chain, has a reactive curing group at the terminal, and can be cured by moisture. The reactive curing group is a functional group having a structure that generates a silanol group by reacting with an active hydrogen group-containing compound such as water. Depending on the type of protecting group to be eliminated, there are dealcohol-type, deoxime-type, deacetate-type, deamid-type, and deacetone-type.
Preferred silicone polymers (polyorganosiloxanes) are obtainable by providing at least one polyorganosiloxane, which has at least one hydroxy group bound to a silicon atom. Preferably, the polyorganosiloxane has at least two hydroxy groups bound to a silicon atom. It is preferred, in addition, that the hydroxy group or hydroxy groups are bound to terminal silicon atoms. If the polyorganosiloxane is branched, it preferably has a hydroxy group at each end.
Silane modified polymer generally refer to silane-modified polyether polyols, silane modified polyacrylates, silane-modified polyurethanes, and silane-modified polyetherpolyurethanes, i.e., polymers featuring hydrolysable silyl groups at the terminal ends of the respective prepolymer main chain.
Examples of the silane modified polymer include an oxyalkylene polymer having a reactive silicon group at the terminal. The reactive silicon group is a group having a hydroxyl group or a hydrolyzable group bonded to a silicon atom and capable of crosslinking by forming a siloxane bond. Specific examples of such silane modified polymers include Kaneka's products MS Polymer S303, MS Polymer S203, Silyl EST280, EST250, SAT200, SAT350, SAT400, and MA440A.
In some embodiments of the present invention, the moisture-curable adhesive composition comprising, based on the total weight of the adhesive composition, at least 10 wt. %, or at least 20 wt. %, or at least about 25 wt. %, or at least about 30 wt. %, or at least about 35 wt. %of the silicone polymer or the silane modified polymer. In some preferred embodiments, up to about 90 wt. %, or up to about 80 wt. %, or up to about 65 wt. %, or up to about 50 wt. %, or up to about 45 wt. %of the silicone polymer or the silane modified polymer. A preferred amount includes 10-90 wt. %, or 20-80 wt. %, or 30-70 wt. %or 40-50 wt. %.
Filler
The present adhesive composition may also include a filler component. For example, any commercially available calcium carbonate can be used with the present invention. The calcium carbonate should be present, for example, in an amount from about 0.2 to about 70%by weight of the total composition. Desirably, the calcium carbonate is present in an amount from about 30 to about 50%by weight of the total composition. More desirably, the calcium carbonate is present in an amount from about 35%to about 45%by weight of the total composition.
Other fillers may also be used with the present invention. These fillers include, for example, lithopone, zirconium silicate, MQ silicone resin, silica, fume silica, hydroxides, such as hydroxides of calcium, aluminum, magnesium, iron and the like, diatomaceous earth, carbonates, such as sodium, potassium, and magnesium carbonates, oxides, such as zinc magnesium, chromic, zirconium and aluminum oxides, calcium clay, graphite, synthetic fibers and mixtures thereof.
A commercially available example of a calcium carbonate filler suitable for use in the present invention is sold by Omya, Inc. under the tradename OMYACARB UF-FL. Any commercially available precipitated calcium carbonate can be used with the present invention.
Catalyst
The adhesive compositions of the present invention may also include a moisture cure catalyst, for example dialkyltin dicarboxylates, alkyl titanates and metal alkoxides, to increase the rate of curing, including increasing the rate of condensation crosslinking reactions. Nonlimited examples of moisture cure catalysts include, for example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin maleate, dialkyl tin hexoate, dioctyltin dilaurate, iron octanoate, zinc octanoate, lead octanoate, cobalt naphthenate, tetrapropyltitanate and tetrabutyltitanate. Other conventional catalysts can also be incorporated into the present invention. For example, the inventive compositions also include an addition cure catalyst. Suitable addition cure catalysts that can be used with the present compositions include platinum-based ones, such as platinum-siloxane complexes, which facilitate hydrosilation reactions. Elevated temperatures may also be used to cure the inventive compositions of the present invention. The catalysts may be used in an amount within the range of about 0.01%to about 3%by weight of the total composition. Desirably, the catalyst is present from about 0.1%to about 2.0%weight of the total composition. Photoinitiators, such as visible and UV initiators may also be incorporated.
Adhesion promoter
The present adhesive composition also includes an adhesion promoter, wherein the adhesion promoter comprises an amnio functional silane or amnio functional silane oligomer, an epoxy functional silane or epoxy functional silane oligomer and a silane compound having the formula (I) : R-Si (R₁) ₃ or its oligomer, each R₁ being independently selected from hydroxy, alkoxy, alkyl, sulfhydryl, halogen, epoxy group or amino group with the proviso that at least two R₁ are alkoxy, and R being an organic group containing alkyl, phenyl, alkenyl, alkynyl or acrylate group, and the silane compound having the formula (I) having an alkyl, phenyl, alkenyl, alkynyl or acrylate functionality of equal to or greater than 1, or more preferred equal to or greater than 2.
< Amnio functional silane or amnio functional silane oligomer >
Suitable amnio functional silane or amnio functional silane oligomer that can be used in the present invention may have an amino functionality of equal to or greater than 1, or more preferred equal to or greater than 2.
The amnio functional silanes may be one or more selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, aminomethyltrimethoxysilane, aminomethyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, (N-2-aminoethyl) -3-aminopropyltrimethoxysilane, (N-2-aminoethyl) -3-aminopropyltriethoxysilane, diethylenetriaminopropyltrimethoxysilane, phenylaminomethyltrimethoxysilane, (N-2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3- (N-phenylamino) propyltrimethoxysilane, 3-piperazinylpropylmethyldimethoxysilane, 3- (N, N-dimethylaminopropyl) aminopropylmethyldimethoxysilane, tri [ (3-triethoxysilyl) propyl] amine, tri [ (3-trimethoxysilyl) propyl] amine, and the oligomers thereof, 3- (N, N-dimethylamino) propyltrimethoxysilane, 3- (N, N-dimethylamino) -propyltriethoxysilane, (N, N-dimethylamino) methyltrimethoxysilane, (N, N-dimethylamino) methyltriethoxysilane, 3- (N, N-diethylamino) propyltrimethoxysilane, 3- (N, N-diethylamino) propyltriethoxysilane, (N, N-diethylamino) methyltrimethoxysilane, (N, N-diethylamino) methyltriethoxysilane, bis (3-trimethoxysilyl) propylamine, bis (3-triethoxysilyl) propylamin, and mixtures thereof, particularly preferably of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, aminomethyltrimethoxysilane, aminomethyltriethoxysilane, 3- (N, N-dimethylamino) propyltrimethoxysilane, 3- (N, N-dimethylamino) propyltriethoxysilane, (N, N-dimethylamino) methyltrimethoxysilane, (N, N-dimethylamino) methyltriethoxysilane, 3- (N, N-diethylamino) propyltrimethoxysilane, 3- (N, N-diethylamino) propyltriethoxysilane, (N, N-diethylamino) methyltrimethoxysilane, (N, N-diethylamino) methyltriethoxysilane, bis (3-trimethoxysilyl) propylamine, and bis (3-triethoxysilyl) propylamine.
In some preferred embodiments, the suitable amnio functional silanes comprise 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, aminomethyltrimethoxysilane, aminomethyltriethoxysilane, (N-2-aminoethyl) -3-aminopropyltrimethoxysilane.
The amnio functional silane oligomers of the present invention are obtained by hydrolytic condensation of monomeric amnio functional silane compounds disclosed above.
An example of a commercial product is the Dynasylan 1146 oligomers available from Evonik.
< Epoxy functional silane or epoxy functional silane oligomer >
Suitable epoxy functional silane or amnio functional silane oligomer adhesion promoter that can be used in the present invention may have an epoxy functionality of equal to or greater than 1, or more preferred equal to or greater than 2.
The epoxy functional silane adhesion promoter is selected from 3-glycidoxyethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) propyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethylmethyldimethoxysilane, and mixtures thereof.
In some of the embodiments of present invention, the mole ratio of the amino group of amnio functional silane/amnio functional silane oligomer to the epoxy group of the epoxy functional silane/epoxy functional silane oligomer is 1.0: 1 to 2.95: 1, preferably is 1.2: 1 to 2.93: 1, or is 1.3: 1 to 2.95: 1.
The epoxy functional silane oligomer useful in the present invention are based on an epoxy silane oligomer synthesized by the controlled hydrolysis and condensation of a catalyst using an epoxy silane monomer. The epoxy silane monomer may be a glycidoxy or cycloaliphatic epoxy silane having one or more functional alkoxy groups or the epoxy silane monomer may be based on a glycidoxy ring in combination with other monomeric silanes. An example of a commercial product is the CoatOSil MP200 available from Momentive Performance Materials Inc or CG-560M available from Jiangxi Chenguang New Material.
< Silane compound or silane oligomer>
Adhesion promoter suitable for present invention comprises a silane compound having the formula (I) R-Si (R₁) ₃ or its oligomer, each R₁ being independently selected from hydroxy, alkoxy, alkyl, sulfhydryl, halogen, epoxy group or amino group with the proviso that at least two R₁ are alkoxy and R being an organic group containing alkyl, phenyl, alkenyl, alkynyl or acrylate group, and the silane compound having the formula (I) having an alkyl, phenyl, alkenyl, alkynyl or acrylate functionality of equal to or greater than 1, or more preferred equal to or greater than 2.
Suitable silane compound having the formula (I) comprises vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyl tris (methylethyl ketoximino) silane, vinyl tris (isopropenyloxy) silane, vinyldimethoxy (methylamino) silane, acryloxypropyltrimethoxysilane, Methacryloxypropyltrimethoxysilane , benzene, [2- (trimethoxysilyl) ethynyl] -, trimethoxy [ (trimethylsilyl) ethynyl] silane.
In some of the embodiments of present invention, the silane oligomers of the present invention are obtained by hydrolytic condensation of monomeric silane compounds having the formula (I) as disclosed above.
In some of the embodiments of present invention, the mole ratio of the alkyl, phenyl, alkenyl, alkynyl or acrylate group of the silane compound having the formula (I) /its oligomer to the epoxy group of the epoxy functional silane/epoxy functional silane oligomer is 0.65: 1 to 2.5: 1, preferably is 0.65: 1 to 2: 1, or 0.69: 1 to 1.6: 1.
The adhesion promoters, when present, may be used in an amount within the range of about 5%to about 15%by weight of the total composition. Desirably, the adhesion promoter is present from about 8%to about 14%by weight on the total composition.
The combination of three types of silane adhesion promoters surprisingly provides a moisture-cured adhesive having good bonding properties on various low energy surfaces.
In some embodiments of present invention, three types of silane adhesion promoters, which may provide specific organofunctional characteristics such as vinyl, epoxy, methacryloyl, alkyl, polyalkylene oxide, etc. It should be understood that alternatively, the functional groups listed need not necessarily all be provided by separate silanes. For example, a silane comprises both vinyl group and amino group provides vinyl group as well as amino group, which could be used as both amino functional silane and silane compound having the formula (I) in present invention.
Wetting agent
Wetting agents operative herein illustratively include methyl (propoxylhydroxide, ethoxylated) bis (trimethylsiloxy silane) , siloxane polyalkynleneoxide copolymer, siloxane polyether copolymer, polydimethyl siloxane polyethylene, oxide-propyleneoxide copolymer, polydimethyl siloxane silicone fluid, polyalkyleneoxide modified heptamethyltrisiloxane fluorinated alkylalkoxylate fluorocarbon telomere B monoether with polyethylene glycols, ethoxylated tetramethyl decanediol and combinations thereof.
Typically, the crosslinkers used in of the present compositions are present from about 0.01 wt. %to about 4%by weight of the total adhesive composition. In some preferred embodiments, the wetting agent has a concentration of from 0.1 wt. %to 2 wt. %based on the total weight of the adhesive composition.
Organic acid metal salt
The moisture-curable adhesive composition of the present invention further comprises organic acid metal salt.
In some embodiments, the organic acid metal salt comprises metallic acrylate salt or metallic methacrylate salt.
Examples of such salts include, but are not limited to, zinc diacrylate, zinc dimethacrylate, zinc monomethacrylate, and sodium acrylate, such as those from the HSC Gray Valley brand known as Dymalinks.
The adhesive composition contains the the organic acid metal salt in adhesive composition, at concentrations of approximately 0.01 wt. %to 5.0 wt. %based on the total weight of the adhesive composition.
By employing the organic acid metal salt, the adhesive made by the moisture-curable adhesive composition has an even better adhesion property on various low energy surfaces.
Crosslinker & Other additives
The present moisture-curable adhesive compositions may also include one or more crosslinkers. The crosslinkers may be a hexafunctional silane, though other crosslinkers may also be used. Examples of such crosslinkers include, for example, methyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, methyltriacetoxysilane, vinyltriacetoxysilane, methyl tris (N-methylbenzamido) silane, methyl tris- (isopropenoxy) silane, methyl tris- (cyclohexylamino) silane, methyl tris (methyl ethyl ketoximino) silane, vinyl tris- (methyl ethyl ketoximino) silane, methyl tris- (methyl isobutyl ketoximino) silane, vinyl tris- (methyl isobutyl ketoximino) silane, tetrakis- (methyl ethyl ketoximino) silane, tetrakis- (methylisobutyl ketoximino) silane, tetrakis- (methyl amyl ketoximino) silane, dimethyl bis- (methyl ethylketoximino) silane, methyl vinyl bis- (methyl ethyl ketoximino) silane, methyl vinyl bis- (methyl isobutyl ketoximino) silane, methylvinyl bis- (methyl amyl ketoximino) silane, tetrafunctionalalkoxy-ketoxime silane, tetrafunctional alkoxy-ketoximinosilane, tris-or tetrakis-enoxysilane, tris-or tetrakis-lactate amidosilane and tris-or tetrakis-lactate estersilane.
Typically, the crosslinkers used in of the present compositions are present from about 1 to about 10%by weight of the total composition. The exact concentration of the crosslinker; however, may vary according to the specific reagents, the desired cure rate, molecular weight of the silicone used in the compositions.
The crosslinking reaction is a condensation reaction and leads to a product of crosslinked network through Si-O-Si covenant bond among the moisture reactive components.
The present moisture-curable adhesive compositions may also contain other additives so long as they do not inhibit the curing mechanism or intended use. For example, conventional additives such as pigments, inhibitors, odor masks, rehology agents and the like may be included.
To avoid swelling of low energy substrates, especially rubber-based substrates, solvent is not employed in present invention.
Preparing Method of the moisture-curable adhesive composition
The preparation of the moisture curable composition can take place by mixing the moisture curable network silicone polymer in the invention, moisture cure catalyst, fillers, and optionally the other ingredients. This mixing process can take place in suitable dispersing units, e.g., a high-speed mixer, planetary mixer and Brabender mixer. In all cases, care is taken that the mixture does not come into contact with moisture, which could lead to an undesirable curing. Suitable measures are sufficiently known in the art: mixing in an inert atmosphere under a protective gas and drying/heating individual components before addition.
Listing of Embodiments
1. An adhesive composition comprising:
(a) at least a silicone polymer or a silane modified polymer,
(b) a filler,
(c) an effective amount of catalyst,
(d) an amnio functional silane or amnio functional silane oligomer, the amnio functional silane or amnio functional silane oligomer having an amino functionality of equal to or greater than 1,
(e) an epoxy functional silane or epoxy functional silane oligomer, and the epoxy functional silane or epoxy functional silane oligomer having an epoxy functionality of equal to or greater than 1,
(f) a silane compound having the formula (I) or its oligomer,
R-Si (R₁) ₃ (I)
each R₁ being independently selected from hydroxy, alkoxy, alkyl, sulfhydryl, halogen, epoxy group or amino group with the proviso that at least two R₁ are alkoxy, and R being an organic group containing alkyl, phenyl, alkenyl, alkynyl or acrylate group, and the silane compound having the formula (I) or its oligomer having an alkenyl, alkynyl or acrylate functionality of equal to or greater than 1,
wherein the mole ratio of the amino group of amnio functional silane /amnio functional silane oligomer to the epoxy group of the epoxy functional silane /epoxy functional silane oligomer being 1.0: 1 to 2.95: 1, and the mole ratio of the alkyl, phenyl, alkenyl, alkynyl or acrylate group of the silane compound /its oligomer having the formula (I) to the epoxy group of the epoxy functional silane /epoxy functional silane oligomer being0.65: 1 to 2.5: 1.
2. The adhesive composition of embodiment 1, wherein the adhesion composition further comprises a wetting agent.
3. The adhesive composition of embodiment 2, wherein the wetting agent comprises at least one of methyl (propoxylhydroxide, ethoxylated) bis (trimethylsiloxy silane) , siloxane polyalkynleneoxide copolymer, siloxane polyether copolymer, polydimethyl siloxane polyethylene, oxide-propyleneoxide copolymer, polydimethyl siloxane silicone fluid, polyalkyleneoxide modified heptamethyltrisiloxane fluorinated alkylalkoxylate fluorocarbon telomere B monoether with polyethylene glycols, ethoxylated tetramethyl decanediol.
4. The adhesive composition of any one of preceding embodiments 2 or 3, wherein the wetting agent has a concentration of from 0.1 wt. %to 2 wt. %based on the total weight of the adhesive composition.
5. The adhesive composition of any one of preceding embodiments, wherein the adhesion composition further comprises an organic acid metal salt.
6. The adhesive composition of embodiment 5, wherein the organic acid metal salt comprises metallic acrylate salt or metallic methacrylate salt.
7. The adhesive composition of any one of embodiments 5 or 6, wherein the organic acid metal salt has a concentration of 0.01wt. %to 5.0 wt. %based on the total weight of the adhesive composition.
8. The adhesive composition of any one of preceding embodiments, wherein the epoxy functional silane is selected from 3-glycidoxyethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) propyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethylmethyldimethoxysilane, and mixtures thereof.
9. The adhesive composition of any one of preceding embodiments, wherein the amnio functional silane is selected from N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N-(2-aminoethyl) -3-aminopropyltrimethoxysilane, N- [3- (trimethoxysilyl) propyl] ethylenediamine, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-methylaminopropyltrimethoxysilane, and mixtures thereof.
10. The adhesive composition of any one of preceding embodiments, wherein the silane compound having the formula (I) comprises vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyl tris (methylethyl ketoximino) silane, vinyl tris (isopropenyloxy) silane, vinyldimethoxy (methylamino) silane.
11. The adhesive composition of any one of preceding embodiments, wherein the mole ratio of the amino group of amnio functional silane /amino functional silane oligomer to the epoxy group of the epoxy functional silane /epoxy functional silane oligomer is 1.2: 1 to 2.95: 1.
12. The adhesive composition of any one of preceding embodiments, wherein the mole ratio of the alkenyl, alkynyl or acrylate group of the silane compound /its oligomer having the formula (I) to the epoxy group of the epoxy functional silane /epoxy functional silane oligomer is 0.65: 1 to 2.0: 1.
13. The adhesive composition of any one of preceding embodiments, wherein the composition is applied to or is on a low energy surface.
14. The adhesive composition of embodiment 13, wherein the low energy surface is a rubber-based surface.
15. The adhesive composition of any one of embodiments 13 or 14, wherein the low energy surface comprises ethylene propylene diene monomer compounded rubber, styrene butadiene rubber, isobutylene isoprene rubber, nitrile butadiene rubber.
16. A method of using an adhesive composition which comprises:
a) applying an adhesive composition of any one of embodiments 1 to 12 on a first substrate.
b) attaching a second substrate to the fist substrate to form an article, and
c) curing the article.
17. The method of embodiment 16, in which at least one of the substrates has low energy surface, the low energy surface is a rubber-based surface. Preferably, the low energy surface comprises ethylene propylene diene monomer compounded rubber, styrene butadiene rubber, isobutylene isoprene rubber, nitrile butadiene rubber.
18. An adhesive comprising a cured product of the adhesive composition according to any one of embodiments 1-12.
19. An article comprising a first substrate, a second substrate and a cured adhesive composition disposed between and adhering the first substrate and the second substrate, wherein the cured composition is the cured product of the adhesive composition according to any one of embodiments 1-12.
20. An automotive loudspeaker comprising an article of embodiment 19.
Examples:
The present invention will be further described and illustrated in detail with reference to the following examples. The examples are intended to assist one skilled in the art to better understand and practice the present invention, however, are not intended to restrict the scope of the present invention. All numbers in the examples are based on weight unless otherwise stated.
Raw Materials
*All raw materials are directly used without any special treatment.
Example 1
<Preparation of moisture-curable adhesive composition>
For the preparation of moisture-curable adhesive composition E1, Kaneka S 303H (440g) , Socal U1 S1-G (437g) and Monarch 700 (3 g) were added and mixed by planetary mixer for 30 mins at 600 rpm. Then Efka RM 1920 (10 g) was added, heated to 56 ℃ and mixed for 30mins at 600 rpm. Cooled down the system and added Dyansylan VTMO 30 g) , Dynasylan AMMO (30 g) , Dynasylan GLYMO (30 g) and mixed for 10mins at 400rpm. TIB KAT 216 (20 g) were added into the system and mixed for 5 mins at 600. Vacuum is needed during all mixing.
<Curing of moisture-curable adhesive composition>
Cleaned the substrate (s) surface thoroughly with IPA, ethyl acetate or acetone before adhesive bead application. Put the Teflon mold (thickness 8mm with a square hollow: 8mm wide*100mm length) on the substrates and fixed the position of the mold with 25mm length of the hollow square on the release tape (s) or film (s) . Applied adhesive (s) to the hollow square of the Teflon mold. At least 3 beads of adhesive should be applied. Allowed the beads to cure at 23±2℃/50±5%RH condition for 7 days or other conditions such as different aging conditions according to the test program.
The cured adhesive samples were subjected to various of tests.
Example 2-10, and CE1-CE6
The curable adhesive compositions of E2 to E10, CE1 to CE6 were prepared in reference to Example 1. There is no epoxy functional silane in CE1. The curable adhesive composition of E2 to E10 and CE1 to CE6 were cured in reference to Example 1. More details are listed in below result part.
Test Methods
<Knife bead adhesion Test >
The knife bead adhesion test covers the determination of adhesives to substrates, PP Plasma treated, ethylene propylene diene monomer compounded rubber (EPDM) , styrene butadiene rubber (SBR) , isobutylene isoprene rubber (IIR) and nitrile butadiene rubber (NBR) .
After curing, the scraping step was performed by cutting a leading edge of the bead to form a loose tab with a length of approximately 25 ± 5 mm to be secured in a gripping toot, such as a vice grip. The loose tab was then gripped by the gripping tool so that the bead is pulled back on itself.
While pulling, at every 6 ± 2 mm of the bead, a 45° angle relative to the low surface energy substrate panel was cut with a knife. The test process is shown in the following figure 1.
Evaluation of the adhesion:
The failure modes of adhesives include adhesion failure (AF) and cohesive failure (CF) .
Adhesion failure (AF) refers to bond failure at the interface between the adhesive and the substrate. Cohesive failure (CF) refers to failure of bonding within the adhesive layer.
Compared with the adhesion failure (AF) , the cohesive failure (CF) indicates that the bonding is more stable, and the bonding effect is better.
An estimation of the amount of cohesion failure (CF) was reported as an area percentage. Degree of failure, represented in percent (%) of test area per present failure modes. In general, cohesion failure was categorized into below groups.
Cohesion Rating Scale:
Excellent: ≥70%CF to all substrates;
Good: ≥40%CF to all substrates;
Pass: ≥30%CF to all substrates;
Not Pass: less than 30%CF to all substrates.
The adhesive composition was deemed to pass the knife bead adhesion test if the cohesion failure was large, i.e., the cohesion failure was equal to or greater than 30%CF to all substrates.
Results
Table 1.
Table 1 shows compositions of the moisture-curable adhesives E1-E10.
Table 2.
Table 2 shows comparative compositions of the curable adhesives CE1-CE6.
Table 3
Table 3 shows adhesion testing (Knife Bead Adhesion Test) results of the curable epoxy adhesives E1-E10 on various low surface energy substrates.
Table 4
Table 4 shows adhesion testing (Knife Bead Adhesion Test) results of the curable epoxy adhesives CE1-CE6 on various low surface energy substrates.
In Examples 1 to 10, the moisture-curable adhesive compositions were prepared according to the formulations provided by the present invention. These formulations especially included the silicone polymer or silane modified polymer, a filler, an effective amount of catalyst, and three types of adhesion promoters. It can be seen that when the contents of the claimed components of the present invention are within certain ranges, three types of adhesion promoters can act synergistically, such that the prepared adhesive have good adhesion property on various low energy surfaces comprising PP Plasma treated, EPDM, SBR, NBR and IIR.
In comparative examples 1, the curable adhesive compositions were prepared without epoxy functional silane. The cured adhesive compositions don’ t have desired good adhesion properties on all required low surface energy substrates.

Claims

An adhesive composition comprising:

(a) at least a silicone polymer or a silane modified polymer,

(b) a filler,

(c) an effective amount of catalyst,

(d) an amnio functional silane or amnio functional silane oligomer, the amnio functional silane or amnio functional silane oligomer having an amino functionality of equal to or greater than 1,

(e) an epoxy functional silane or epoxy functional silane oligomer, and the epoxy functional silane or epoxy functional silane oligomer having an epoxy functionality of equal to or greater than 1,

(f) a silane compound having the formula (I) or its oligomer,

R-Si (R₁) ₃ (I)

each R₁ being independently selected from hydroxy, alkoxy, alkyl, sulfhydryl, halogen, epoxy group or amino group with the proviso that at least two R₁ are alkoxy, and R being an organic group containing alkyl, phenyl, alkenyl, alkynyl or acrylate group, and the silane compound having the formula (I) or its oligomer having an alkenyl, alkynyl or acrylate functionality of equal to or greater than 1,

wherein the mole ratio of the amino group of amnio functional silane /amnio functional silane oligomer to the epoxy group of the epoxy functional silane /epoxy functional silane oligomer being 1.0: 1 to 2.95: 1, and the mole ratio of the alkyl, phenyl, alkenyl, alkynyl or acrylate group of the silane compound /its oligomer having the formula (I) to the epoxy group of the epoxy functional silane /epoxy functional silane oligomer being0.65: 1 to 2.5: 1.
The adhesive composition of claims 1, wherein the adhesion composition further comprises a wetting agent.
The adhesive composition of claims 2, wherein the wetting agent comprises at least one of methyl (propoxylhydroxide, ethoxylated) bis (trimethylsiloxy silane) , siloxane polyalkynleneoxide copolymer, siloxane polyether copolymer, polydimethyl siloxane polyethylene, oxide-propyleneoxide copolymer, polydimethyl siloxane silicone fluid, polyalkyleneoxide modified heptamethyltrisiloxane fluorinated alkylalkoxylate fluorocarbon telomere B monoether with polyethylene glycols, ethoxylated tetramethyl decanediol.
The adhesive composition of claims 2, wherein the wetting agent has a concentration of from 0.1 wt. %to 2 wt. %based on the total weight of the adhesive composition.
The adhesive composition of claims 1, wherein the adhesion composition further comprises an organic acid metal salt.
The adhesive composition of claims 5, wherein the organic acid metal salt comprises metallic acrylate salt or metallic methacrylate salt.
The adhesive composition of claims 5, wherein the organic acid metal salt has a concentration of 0.01wt. %to 5.0 wt. %based on the total weight of the adhesive composition.
The adhesive composition of claims 1, wherein the epoxy functional silane is selected from 3-glycidoxyethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) propyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethylmethyldimethoxysilane, and mixtures thereof.
The adhesive composition of claims 1, wherein the amnio functional silane is selected from N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- [3- (trimethoxysilyl) propyl] ethylenediamine, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-methylaminopropyltrimethoxysilane, and mixtures thereof.
The adhesive composition of claim 1, wherein the silane compound having the formula (I) comprises vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyl tris (methylethyl ketoximino) silane, vinyl tris (isopropenyloxy) silane, vinyldimethoxy (methylamino) silane.
The adhesive composition of claim 1, wherein the mole ratio of the amino group of amnio functional silane /amino functional silane oligomer to the epoxy group of the epoxy functional silane /epoxy functional silane oligomer is 1.2: 1 to 2.95: 1.
The adhesive composition of claim 1, wherein the mole ratio of the alkenyl, alkynyl or acrylate group of the silane compound /its oligomer having the formula (I) to the epoxy group of the epoxy functional silane /epoxy functional silane oligomer is 0.65: 1 to 2.0: 1.
The adhesive composition of claims 1, wherein the composition is applied to or is on a low energy surface.
The adhesive composition of claims 1, wherein the low energy surface is a rubber-based surface.
The adhesive composition of any one of claims 13 or 14, wherein the low energy surface comprises ethylene propylene diene monomer compounded rubber, styrene butadiene rubber, isobutylene isoprene rubber, nitrile butadiene rubber.
A method of using an adhesive composition which comprises:

a) applying an adhesive composition of at least one of claims 1 to 12 on a first substrate.

b) attaching a second substrate to the fist substrate to form an article, and

c) curing the article.
The method of claim 16, in which at least one of the substrates has low energy surface, the low energy surface is a rubber-based surface.
An adhesive comprising a cured product of the adhesive composition according to any one of claims 1-12.
An article comprising a first substrate, a second substrate and a cured adhesive composition disposed between and adhering the first substrate and the second substrate, wherein the cured composition is the cured product of the adhesive composition according to any one of claims 1-12.
An automotive loudspeaker comprising an article of claim 19.