CA1095926A - Isocyanto-functional organo silanes and adhesives therefrom - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The invention provides isocyanatosilanes characterized by the presence of at least one free isocyanate group and containing a single silane grouping having the structure:

Description

1~S~3i2~i This invention relates to adhesive compositions suitable for bonding elastomeric materials, especially vulcaniz-able elastomeric materials, at elevated temperatures to inorganic substrates and to other substrates including thernselves.

, In par-ticular, the present invention relates to isocyanato silanes particularly useful in said adhesive compositions.
This application is a divisional application of copending application No. 233,912 filed August 21, 1975.
It is well-known to employ adhesive compositions for lQ bonding elastomeric materials to subs~rates, including elastomeric, fabric, metal, and other solid substrates. In the as yet unconsumma~ed search for the ideal all-purpose adhesive, there have been developed a variety of adhes`ive compositions which have been utilized with varying degrees of success in bonding elastomeric materials to themselves or to other substrates ~o form laminates and composite articles. As a general rule, the known adhesives which have been effective as single-coat rubber-to-metal bonding agents are limited with respect to the type of elastomer to be bonded. That is to say, an adhesive which is capable of providing an acceptable bond with butadiene/styrene elastomers may be unsatisfactory with ethylene/propylene/non-conjugated diene terpolymer (EPDM) elastomer or polyisobutylene/
isoprene ~S926 elastomer. This lack of versatility which is characteristic of the general class of one-coat adhesive systems can be partially alleviated by the use of two-coat adhesive systems which utilize a primer coat applied over the metal substrate and a cover coat (which adheres well to the elastomer) interspersed between the elastomer and the primer~ In addition to the problem of versatility, both the one-coat and two-coat adhesive systems suffer from one or more other disadvantages, includin~ a general inability -to afford optimum adhesion, particularly at elevated service temperatures; poor storage stability at room and/or elevated temperatures; poor resistance to prebake; and the resistance of the adhesive bond to environmental conditions such as solvents, moisLure and the li]ce, is too often poorer than is normally desired in many commercial applications. Thus, there remains a need for more effective adhesive formulations, particu-larly one-coat adhesive formulations which can be employed in bonding elastomer;~c materials to various substrates including themselves, which are shelf--stable for extended periods prior to use, which can be employed with a variety of elastomeric materials, and which are resistant to degradation from environmentai,factors~
In copending application No. 233,912 there is provided adhesive compositions for bonding a variety of elastomers at elevated temperatures to various substrates, particularly metal substrates, which adhesive compositions which afford strong eiastomer-substrate adhesive bonds and which adhesive bonds exhibit high environmental resistance.
The advantages of the invention of the copending application including a method for bonding elastomeric materials to substrates, and adhesivelv~joined elastomer-substrate composites, will be readily apparent from a consideration of the following~

~95~

In accordance with the invention of the copending application, it has been discovered that compositions comprising at least one isocyanto organosilanet preferably in combination with at least one polyisocyanate characterized by tha presence of at least two free isocyanate groups, are unexpectedly effective as adhesive materials for bonding a variety of elastomers, particularly vulcanizable elastomers, to inorganic substrates.
The isocyanato functional organosilanes, which will be referred to hereafter as isocyanatosilanes, which are suitable for use in the invention of the copending application can be broadly described as those compounds capable of undergoing both the hydrolytic reactions typical of alkyl esters of silicic acid and the reactions with active hydrogen-containing compounds typical of isocyanates.
In addition to affording strong adhesive bonds with a variety of elastomers, the compositions of the invention improve the environmental resistance of the bonded assembly.
It has also been discovered that the incorporation of one or more aromatic nitroso com~cunds can-improve the strength of the adhesive bond and/or improve the environmental resistance, and can further extend the versatility of the adhesive compositions.
It has further been discovered that the inclusion of one or more polymeric film-forming adjuncts can provide further improvements, particularly in~relation to film properties. The compositions of the invention provide strong bonds which is highly desired in many commercial applications. A particularly unexpected feature of the invention is the capability of the herein described compositions to function as single-package, one-coat adhesive systems which afford strong rubber-to-metal adhesive bonds ha~ing an improved resistance to environmental attack. In addition, the preferred adhesive compositions of the invention are further characterized by their stability at ambient.

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tem~eratures during storage and handling.
The reason for the i~pr~vement in stability is not fully understood. Generally, adhesive compositions comprising free isocyanate-containing materials have a limited pot life, due to the high reactivity of the isocyanate group with water and other active hydrogen-containing compounds. The inclusion of aromatic nitroso compounds and/or polymeric film-forming adjuncts introduces impurities such as water and reactive oximes which would be expected to have a deleterious effect on stability, since such impurities tend to hydrolyze both the isocyanate and the silicic ester portions of the isocyanato organosilane and also react with the other components, e.g., through the free isocyanate groups of the free polyisocyanate, thereby leading to premature gelation of the adhesive compositions. It is hypothesized that the improvement in stability could be due to the acidic buffering which is inherent in the oompositions of this invention due to any or all of the latent, i.e., free, acidity of the polyisocyanate component, an acidic contribution from random and dissociated free silicic acid groups, or an acid-ic contribution from the polymeric film-forming adjunct. This postulation is disclosed in U.S. Patent No. 3,830,784, issued August 20, 1976 to Manino and Sexsmith, which is directed to improvements in shelf stability, i.e., storage and handling stability of rubber-to-metal bonding compositions containing free polyisocyanates. The same means of improving shelf stability taught under U.S. 3,830,784 may in fact be operative for the com-positions of the present invention.
The isocyanatosilanes employed in the invention of ~he copending applicat:ion are characterized by the presence of at least one free isocyanate moiety and at least two hydrolyzable groups according to the general formula 5~:6 OCN _ Z Si _(OR )3-a wherein Rl is a monovalent aliphatic, cycloaliphatic or aromatic radiaal having from 1 to 20 carbon atoms, and is preferably selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms, cycloalkyl radicals having from 4 to 7 ring carbon atoms, aryl radicals having 6, 10, or 14 nuclear carbon atoms, and such aryl radicals containing one or more substituent alkyl groups having from 1 to 4 carbonatoms;
R2 is a monovalent aliphatic, cycloaliphatic or aromatic organic radical containing from 1 to 8 carbon atoms and is preferably selected from the group consisting of alkyl radicals having from 1 to d carbon atoms, O
~ R - O - R4, and- ~ ~ R4, where R3 is an alkylene group having from 1 to 4 carbon atoms and R4 is an alkyl group having from 1 to 4 carbon atoms; a is zero or 1, and preferably is zero;
and Z is a divalent organic radical attached to the silicon atom yia a carbon-silicon bond. The exact nature of the Z radical is 2Q not critical, i.e., the radical can have any configuration and combination of groupings that are compatible with the isocyanto groups. For example, the Z radical can be a hydrocarbon radical, or it can contain linkages such as ether, ureido, urethane, and th;ourethane linkages The Z radical can, of course, contain substituent groups such as halogen which are compatible with the isocyanato groups.
Isocyanatosilanes which are preferably employed in the practice of the invention of the copending application are selected from the group consisting S~2t~;

of (1) isocyanatosilanes ha~ing the general formula Rl OCN - R - li - (oR2)3 or (2) isocyanatosilane adducts of multifunctional /~rganosilanes and poly-isocyanates, said adducts having as characteristic feat-ures at least one free isocyanate group and at least one silane grouping having the formula -NH ~ C - A - R _ la _ (oR2) it being understood that said free isocyanate group(s) and said silane grouping(s) are joined to each other through the residue of the ~olyisocyanate reactant. The isocyanatosilane adducts, i.e., the reaction products of multifuntional organosilanes and polyiso-cyanates, are presently preferred for forming adhesive compositions according to the invention. Such adducts are generally easier to prepare and are consequently more readily available than are iso-cyanatosilanes prepared directly from the more basic silane lnter-mediates. (The more basic silane intermediates are for present pur-poses, assumed to be those with the highly reactive - Si-H or -Si - Cl functionality).
In the foregoing formulae, R , R and a are as previously defined; R is selected from the group consisting of divalent hydrocarbon and halogenated hydrocarbon radicals having from 1 to 20, preferably 2 to 9, carbon atoms;

~ - 6 -` ~9S~2~

A is selected from the group consisting of - O -, - S -, N - , and other groups containing an active hydrogen; and R is a divalent aliphatic, cycloaliphatic, or aromatlc radical having from 1 to 20 carbon~atoms, and is-Preferably an alkylene radical having from 1 to 9 carbon atoms. Especially Dreferred are adducts in which A is - O - or H-N ' " ; R is an alkylene group having from 2 to 4 carbon atoms, R2 is methyl, ethyl, methoxyethylene or methyl carbonyl, and a is zero.
The present invention provides isocyanato silanes characterised by an isocyanatosilane characterized by the presence of at least one reactive isocyanate group and containing a single silane grouping having the structure O Ra ~ NH ~C ~ NH ~ R ~ (OR )3-a said reactive isocyanate group being connected to said silane grouping through a divalent organic radical having at least one carbon atom, and wherein R is a di~alent aliphatic, cycloaliphatic or aromatic radical having from 1 to 20 carbon atoms;
Rl is a monovalent aliphatic, cycloaliphatic or aromatic radical having from 1 to 20 carbon atoms;
R is a monovalent aliphatic, cycloaliphatic or aromatic organic radical having from 1 to 8 carbon atoms; and a is zero or 1.
Isocyanatosilanes corresponding to the formula Ra OC~ ~R -Si - (OR )3 a are known articles of commerce. Such compounds can be prepared, for example, by the pyrolysis of the corresponding carbamate.
The carbamate can be prepared by effecting reaction between a silylorganohalide~ a metal cyanate and an aliphatic monohydric alcohol in the presence of an aprotic solvent. Another method 5~2~

for preparing such compounds comprises ef~ecting reaction between a silicon hydride and an oîefinically unsaturated isocyanate, such as allyl isocyanate. Such isocyanatosilanes include, without limitation, trimethoxysily:ipropylisocyanate, phenyldiethoxysilylpropylisocyanate, and methyldimethoxysilyl-butvlisocyanate.
The presently preferred isocyanatosilane adducts can be readily prepared by effecting reaction between a multi-functional organosilane and a polyisocyanate by adding the organosilane, preferably as a dilute solution, to the polyiso-cyanate, also preferably diluted, at a temperature in the range from about 10 to about 100C, while agitating the mixture by a mechanical stirrer or similar device. While not essential, a suitable catalyst, such as -7a-dibutyltin dilaurate, can be employed. The reaction is essentially instantaneous particularly wllen catalysts are employed, and is accompanied by a mild exotherm. It is essential that the amount of polyisocyanate present during the reaction be such as to ensure obtaining an adduct having at least one free isocyanate group. Thus, it will be appreciated that the minimum amount, in molar equiva-lents of NCO, of polyisocyanate required to form the adducts of the invention is one molar equivalent of NCO in excess of the amount, in molar equivalents of NCO, required to react with all the active hydrogen of the silane reactant. If desired, the adduct can be separated from the reaction mixture by conventional means. How-ever, it has been found advantageous to add the organosilane reactant ~o a sufficient excess of tne polyisocyanate reactant to ensure complete reaction of the organosilane reactant to afford, on the one hand, an isocyanate adduct having at least one free isocyan-ate group and, on the other hand, a reaction mixture containing sufficient un-reacted polyisocyanate to provide the requisite amount of isocyanate functionality, as will be set forth in greater detail, infra. In this manner, the isolation of the silane-isocyanate adduct from the reaction mixture and the subsequentaddition of the adduct to free polyisocyanate can be dispensed with, thereby affording a significant economic advantage. This method, i.e., contacting the organosilane reactant with excess polyisocyanate reactant, has been found to be particularly advantageous in those instances wherein the adhesive compositions of the invention contain a polymeric film-former adjunct.
As noted, at present it is preferred to employ both the silane and the poly:isocyanate in dilute form. Suitable solvents include aromatic hydrocarbon such as benzene, toluene, xylene, and the li~ei halogenated aromatic hydro-carbon such as monochlorobenzene, dichlorobenzene, and the like;

.

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halogenated aliphatic hydrocarbons, such as trichloroethylene, perchloro-ethylene, propylene dichloride, and the like; ketones, such as methyl isobutyl ketone, methyl ethyl ketone, and the like, ethers and the like; including mixtures of such solvents/diluents.
The degree of dilution is not critical. As long as it does not prohibit an adequate film thickness of the adhesive in the end application.
The multifunctional organosilane compounds which are suitable for use in the practice of the invention are characterized by the presence of a single organic chain containing at least one functional group having at least one extractable, i.e., active, hydrogen atom, such as an amino, mercapto, hydroxy, or other active hydrogen-containing functional group being connected to silicon through an organic group containing at least one carbon atom. Pre-ferably, the functionalgroup containing at least one active ny-drogen atom is connected to the silicon atom by an organic group containing at least two interconnected carbon atoms.
More particularly, the multifunctional organosilane com-pounds which are suitable for use in tne practice of the invention are selected from the group consisting of hydroxyorgano silanes having tne formula Rl HO - R ~ ~i - (oR2)3 whe`rein R is a divalent aliphatic, cycloaliphatic or aromatic rad-ical having from 1 to 20 carbon atoms, and is preferably an alkylene-radical having from 1 to 9, most preferably 2 to 4, carbon atoms;
Rl is a monovalent aliphatic, cycloaliphatic or aromatic radical having from 1 to 20 carbon atoms, and is preferably selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms, cycloalkyl . . ,-. .

592~

radicals ha~ing ~r~m 4 to 7 rin~ carbon atQms~ and aryl radicals having 6, 10, or 14 nuclear carbon atoms, and including such aryl radicals containing one or more subst:ituent alkyl groups having from 1 to 4 carbon atoms;
R is a monovalent aliphatic, cyloaliphatic or aromatic organic radical containing from 1 to 8 carbon atoms, and is pre ferably selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms, R - O - R , and ~ ~ - R , where R is an alkylene group having from 1 to 4 carbon atoms and R4 is an alkyl.
group having from 1 to 4 carbon atoms; and a is zero or 1, prefer-ably zero; aminoorganosilane compounds having the characteristicformula R5 - ~ ~ R - Si (oR2~

wherein R, Rl, R2 and a are as previously defined; and R is selected from the group consisting of hydrogen, monovalent aliphatic radicals having from 1 to 8 carbon atoms, monovalent cycloaliphatic radicals having from 4 to 7 ring carbon atoms, phenyl, alkaryl radicals having 6 nuclear carbon atoms and containing one or more substituent alkyl groups having from 1 to 4 carbon atoms and -R6-NX - R7, wherein R6 is selected from the group consisting of di-valent aliphatic, cycloaliphatic and aromatic radicals having from 1 to 20 carbons, there being preferably at least two carbon atoms separating any pair of nitrogen atoms, with R6 being preferably an alkylene group of 2 to 9 carbon atoms; and R7 being the same as R5 and preferably is hydrogen;

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mercapto organosilane compound~ having the characteristic formula Rl la 2 HS R - Si ~ (OR )3-a' wherein R, Rl, R2 and a are as previously defined; and other or-qanosilane compounds having a single organic chain having from 1 to 20 carbon atoms, said chain having at least one extractable hy-drogen atom, said extractable hydrogen atom preferably being attached to a functional group separated from the silicon atom by a chain of at least 3 interconnected carbon atoms.
The preferred organosilane compounds for use in the prac-tice of the invention are aminoorganosilane compounds as herein described. It will be appreciated that both primary and secondary aminoorganosilane compounds and also such compounds containing in their structure at least one primary amino grouping and one or more secondary amino groupings can be employed in forming the composi-tions of this invention. It is also possible to employ aminoor-ganosilane compounds containing one or more tertiary amino groupings providing such compounds contain also at least one primary or secondary amino grouping. At present, aminoorganosilane compounds characterized by the presence of at least one primary amino group-ing are preferred.
Representative multifunctional organosilanes which are suitable for use in the practice of the invention include without limitation hydroxypropyl-trimethoxysilane, hydroxypropyltriethoxy-silane, hydroxybutyltrimethoxy-silane, g-aminopropyltrimethoxy-silane, g-aminopropyltriethoxysilane, `.L ''--S~2~

methylaminopropyltrimethoxysilane, ~-aminopropyltripropoxysilane, g-aminoisobutyltriethoxysilane, g-aminopropylmethyldiethoxysilane, g-amino-propyletllyldiethoxysilane g-aminopropylphenyldiethoxy-silane, d-amino-butyltriethoxysilane, d-aminobutylmethyldiethoxy-silane, d-aminobutyl-ethyldiethoxysilane, g-aminoisobutylmethyl-diethoxysilane, N-metnyl-g-aminopropyltriethoxysilane, N-phenyl-g-aminoisobutylmethyldiethoxysilane, N-ethyl-d-aminobutyltrie-thoxysilane, N-g-aminopropyl-g-aminopropyl-triethoxysilane, N-~-aminoethyl-g-aminoisobutyltriethoxysilane, N-g-aminopropyl-d-aminobutyltriethoxysilane, N-aminohexyl-g-aminoisobutyl-methyl-diethoxysilane, methylaminopropyltriethoxysilane, g-mercapto-propyltrimethoxysilane, mercaptoethyltriethoxysilane, g-aminopropyl-methoxydiethoxysilane, and the like.
The polyisocyanates which can be employed in the practice of the present invention can be any organic isocyanate having at least two free isocyanate groups. Included within the purview of suitable polyisocyanates are aliphatic, cycloaliphatic, and aromatic polyisocyanates, as these terms are generally interpreted in the art. Thus it will be appreciated that any of the known polyisocya-nates such as alkyl and alkylene polyisocyanates, cycloalkyl andcycloalkylene polyisocyanates, aryl and arylene polyisocyanates, and combinations such as alkylene, cycloalkylene and alkylene arylene polyisocyanates, can be employed in the practice of the present invention. These polyisocyanates can serve both as the free polyisocyanate component of the herein described compositions and as a starting material for the silane-polyisocyanate adduct com-ponent.
Particularly preferred polyisocyanates are the polyalky-lene poly-(aryleneisocyanates) having the formula i3;26 (X)5-m ~X)4-m (~)5-m-rR8~ j R8_~

tNCO)m (NCO)m n . m wherein R8 is a divalent orgallic radical, preferably a divalent aliphatic radical having from 1 to 8 carbon atoms, espe-cially such radicals obtained by removing the carbonyl oxygen from an aldehyde or ketone, and preferably is methylene; m is ld 1 or 2, and is preferably 1; n is a digit having an average value in the range from zero to 15, preferably 0.1 to 4, and most preferably 0.3 to 1.8; and X is selected from the group consisting of hydrogen, halo-~en, alkyl radicals having from 1 to 8 carbon atoms, and alkoxy radicals haviny from 1 to 8 carbon atoms, and pre~erably is hydrogen.
Suitably polyisocyanates include without limitation toly-lene-2, 4~diisocyanate 2, 2,4-trimethylhexamethylene-1, 6-diiso-cyanate; hexamethylene-l, 6-diisocyanate, diphenylmethane-4,

2~ 4'-diisocyanate, triphenylmethane-4 , 4',4-triisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, polymethylene polyphenylisocyanate, m-phenylenediisocyanate, p-phenylene-diiso-cyanate, 2,6--tolylene diisocyanate, 1,5-naphthalenediisocyanate, naphthalene-l, 4-diisocyanate, diphenylene-4,4'-diisocyanate, 3,

3'-bi--tolylene-4,4'-diisocyanate, ethylene diisocyanate; propy-lene-1,2-diisocyanate, butylene-2,3-diisocyanate, ethylidenediiso-cyanate, butylidenediisocyanate, xylylene-i, 4-diisocyanate, xylylene-1,3-diisocyanate, methylcyclohexyl-diisocyanate, cyclo-pentylene-l, 3-diisocyanate, cyclohexylene-l, 4-diisocyanate, S~3126

4,4'-methylene-bis(cyclohexylisocyanate), p-phenylene-2,2'-bis (ethylisocyanate), 4,4~diphenylene ether~2,2~-bis(ethylisocyanate), tris(2,2',2"-ethylisocyanate benzene), 5-chloro--phenylene-1,3-bis (propyl-3-isocyanate), 5-methoxy-phenylene-1, 3-bis(propyl-3-isocyanate), 5-cyanophenylene-1, 3-bis(propyl-3-isocyanate), 4-methyl-phenylene-l, 3-bis(propyl-3-isocyanate), and the like.
Other polyisocyanates which can be employed in the practice of the invention include the aromatic diisocyanate dimers, such as those described in U.S. Patent No. 2,671,082 issued March 2, 1954 to Stallmann. A particularly preferred dimer is the tolylene diiso-cyanate dimer having the formula N N

OC~ O N ~O

The aromatic nitroso compounds which are suitable for use in the practice of the present invention can be any aromatichydrocarbon, such as benzenes, naphthalines, anthracenes, biphenyls, and the like, containing at least two nitroso groups attached dir-ectly to non-adjacent ring carbon atoms. More particularly, such nitroso compounds are described as poly-C-nitroso aromatic com-pounds having from 1 to 3 aromatic nuclei, including fused aromatic nuclei, having from 2 to 6 nitroso groups attached directly to non-adjacent nuclear car~on atoms. The presently preferred poly-C- nit-roso materials are the di-nitroso aromatic compounds, especially the dinitroso-benzenes and dinitrosonaphthalenes, such as the meta-or paradinitroso-benzene~ and the meta-or paradinitrosonaphthalenes.
The nuclear hydrogen s~

atoms of the aromatic nucleus can ~e re~l~ced by alkyl, alkoxy, cycloalkyl, aryl, aralkyl~ alka~yl~ arylamine, arylnitroso, amino, halogen and the like groups. The presence of such substituents on the aromatic nucleus has little effect of the activity of the poly-C-nitroso compounds in the present invention. As far as is presently known, there is no limitation as to the character of the substituent, and such substituents can be organic or in-organic in nature. Thus, where reference is made herein to poly-C-nitroso or di-C-nitroso "aromatic compound","benzenes", or "naphthalenes," it will be understood to include both substituted and unsubstituted nitroso compounds, unless otherwise specified.
Particularly preferred poly-C-nitroso compounds are characterized by the formula (R )p - Ar - (NO)2, wherein Ar is selected from the group consisting of phenylene and naphthalene, R is a monovalent organic radical selected from the group consisting of alkyl, cycloalkyl, aryl, aralkyl, alkaryl, arylamine and alkoxy radicals having from 1 to 20 carbon atoms, amino, or halogen and is preferably an alkyl group having from 1 to 8 carbon atoms; and p is zero, 1, 2, 3, or 4 and is preferably zero.
A partial non-limiting listing of suitable poly-C-nitroso compounds which are suitable for use in the practice of the in-vention include m-dinitroso-benzene, p-dinitrosobenzene, m-dinitro-sonaphthalene, p-dinitrosonaphthalene, 2,5-dinitroso-p-cymene, 2 -methyl-l, 4-dinitrosobenzene, 2-methyl-5-chloro-1, 4-dinitroso-benzene, 2-fluoro-1, 4-dinitrosobenzene, 2-methoxy-1, 3-dinit~o so~enzene, 5-chloro-1, 3-dinitrosobenzene, 2-benzyl-1, 4-dinitro-sobenzene, and 2-cyclohexyl-1, 4-dinitrosobenzene.
Substantially any of the polymeric materials which have been heretofore employed as film formers or film-forming adjuncts in adhesive formulations are suitable for use in the practice of ~-, - 15 -l~ssæ~

the present invention. Such film-forming polyme~ic materials include, without li~itation, thermo-settin~ condensation polymers, such as thermosetting phenolic resins, thermosetting epoxy resins, thermosetting polyester resins, thermosetting triazine resins, and the like; polymers and copolymers of polar ethylenically un-saturated materials, such as poly(vinyl butyral); poly(vinyl formal);
poly(vinyl acetate); chlorinated poly(vinyl chloride); copolymers of vinyl acetate and vinyl chloride; chlorinated copolymers of vinyl acetate and vinyl chloride; polymers of acrylic acid; co-polymers of acrylic acid and conjugated dienes, such as 1,3-butadiene; 2,chloro-1, 3-butadiene; 2,3-dichloro-1, 3-butadiene, and the like, and including after-halogenated products thereof;
polymers of methacrylic acid; copolymers of methacrylic acid and conjugated dienes; copolymers of vinyl pyridine and conjugated .~2 dienes, and including polyvalent reaction products thereof; cellu- :
losic materials such as cellulose acetate butyrate; and the like.
; Particularly preferred film forming materials are halogen-con-taining rubbers, including without limitation, chlorinated natural rubber; polychloroprene; chlorinated polvchloroprene; chlorinated poly-butadiene; chlorinated polyethylene; chlorinated ethylene/
propyLene copolymers; chlorinated ethylene/propylene/non-conjugated diene terpolymers; chlorinated copolymers of butadiene and styrene;
chlorosulfonated polyethylene; brominated poly(2,3-dichloro-1, 3-; butadiene); copolymers of alpha-chloroacrylonitrile and 2,3-dichloro-l, 3-butadiene; copolymers of alpha-bromoacrylonitrile and 2,3-dichloro-1, 3-butadiene; mixtures of such halogen-containing rubbers with hydrohalogenated rubbers of hypohalogenated rubbers;
mixtures of two or rnore such halogenTcontaining rubbers and the like. Other suitab:Le polymeric film-forming adjuncts include cellulosic esters such as cellulose acetate butyrate; natural rubber, butyl rubber, ethylene/propylene copolymer (EP~) rubber, ethylene/
propylene/diene terpolymer (EPDM) rubber, polymers and copolymers .

S9;Z6 of dienes having from 4 to 12 carbon atoms, such as polybutadiene,and including also copolymers of such dienes and one or more different monomers copolymerizable therewith, such as SsR and butadiene/acrylonitrile rubber. As indicated, halogenated poly-meric materials, and particularly chlorinated and brominated rubbers, are preferred film-forming materials in the practice of the invention.
Tne adhesive compositions of this invention are prepared by conventional means, and such well-known techniques will not be discussed here in detail. As a general rule, the silane-iso-cyanate adduct and free polyisocyanate will be mixed prior to incorporating any other ingredients, such as aromatic nitroso compound, film-forming polymeric material, filler, and the like.
In those instances wherein the adduct has been isolated, the adduct will be added directly to the free polyisocyanate, with both materials preferably being diluted, under conditions such as to ensure a homogeneous mixture. In this instance, the free polyisocyanate can be the same as that used in preparing the adduct, it can be different, or it can comprise a mixture of two or more polyisocyanates, one of which can be, if desired, the same polyisocyanate as was used in forming the adduct. In a second and more preferred instance, the adduct is formed from the reaction of the silane and an excess of polyisocyanate to afford a reaction mixture comprising adduct and free polyisocyanate. In this case, if the amount of free polyisocyanate is insufficient to provide the proper free polyisocyanate: adduct relationship, additional free polyisocyanate can be added to the reaction mixture. Such added free polyisocyanate can, of course, be the fiame or different from the polyisocyanate employed in forming the adduct, and can include a mixture of two or more polyisocyanates, one of which can be, if desired, the same polyisocyanate as was employed in forming the adduct. As a general rule~ it is preferred that the amount of ....

1~9S~6 polyisocyanate employed in forming the adduct be such that no additional polyisocyanate need be added to the reaction mixture.
The thus-prepared admixture is itself suitable for use as a primer and adhesive composition; or as a base composition into which the aromatic nitroso compounds, film-forming polymeric materials, filler materials such as carbon black and the like, extenders, pig-ments, diluents, etc., can be incorporated, employing conventional techniques for formulating adhesive compositions.
In forming the adhesive compositions of the present invention, the isocyanatosilane will be present in an amount in the range from about 2.5 to 100, preferably about 2.5 to about 50, and most preferably about 5 to about 40, parts by weight; with the polyisocyanate being present in the amount of 100-x parts by weight, wherein x is equal to the amount, in parts by weight, of isocyanato-silane component. In addition, the isocyanatosilane and free poly-isocyanate must provide a minimum amount of total free isocyanate, including that provided by both the isocyanatosilane and free poly-isocyanate, equal to one molar equivalent of isocyanate per mol of isocyanatosilane. Preferably, the total free isocyanate content will be in a range from 1 to about 20, preferably 1 to about 12, and most preferably 2 to about 8, molar equivalents per mol of isocyanatosilane. It will be appreciated that the invention affords a great deal of flexibility in preparing adhesive compositions including, inter alia, isocyanatosilane per se; isocyanatosilane and aromatic nitroso compound; isocyanatosilane, aromatic nitroso compound and polymeric film-forming adjunct; isocyanatosilane and free polyisocyanate; isocyanatosilane, free polyisocyanate, and aromatic nitroso compound; isocyanatosilane, free polyisocyanate, aromatic nitroso compound, and polymeric film-forming adjunct;
with the compositions comprising isocyanatosilane and free poly-isocyanate being particularly preferred. In those compositions containing aromatic nitroso compounds, polymeric film-forming adjuncts, and inert filler~ ~he ar~matic nitroso compound will generally be p~esent in an amount in the range from about 5 to about 200, preferably from about 50 to about 150, parts by weight;
the polymeric film-forming adjuncts will generally be present in an amount in the range from about 10 to about 200, preferably from about 75 to about 150 parts by weight; and the inert filler will generally be present in an amount in the range from about 10 to about 200, preferably about 25 to about 175, parts by weight; said amounts in each instance being on a basis of 100 parts by combined weight of isocyanatosilane and free polyisocyanate.
As noted previously, in addition to isocyanatosilane, free polyisocyanate, aromatic nitroso compound, polymeric film-forming adjuncts, and inert filler material the adhesive compositions of the invention can include conventional additives such as pigments, extenders, solvent, diluent, and the like with the amount of such additives being within the range conventionally employed.
For ease of application, as is conventional in this art, the components will be mixed and dispersed in a liquid carrier which, once the composition has been applied, can be readily evaporated. Examples of suitable carriers are aromatic and halogenated aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene dichlorobenzene, and the like; halogenated aliphatic hydrocarbons such as trichloroethylene, perchloroethylene, propy-lene dichloride, and the like; ketones such as methyl ethyl ketone, methyl isobutyl ketone, and the like; ethers , naphthas, etc., in-cluding mixtures of such carriers. The amount of carrier is not critical and will ordinarily be such as to provide a total sollds content ranging from about 5 to about 100, i.e., 100 percent solids system, and preferably from about 5 to about 30, percent by weight.
The adhesive compositions of the present invention have been found to be particularly suitable for bonding a wide variety of elastomeric materials, especially vulcanizable .

~S~326 elastomeric materials, to themselves or to other substrates, particularly inorganic substrates. Elastomers whic}l can be bonded include without limitation natural rubber, poly-- l9a -t~
l;~`'`

~S~1Z6 chloroprene ~ubbe~ styrene-butadiene rubber, nitrile rubbe~
ethylene/propylene copolymer rubher (EPM); ethylene/propylene/
diene terpolymer rubber (EPDM); butyl rubber, polyurethane rubber, and the like. Substrates other than the elastomers per se which can be effectively bonded include fabrics such as fiberglass, poly-amides, polyesters, aramids, e.g., Ke~lar, a trademark of E.I. du Pont de Nemours & Company, (Inc), Wilmington, Delaware, and the like; and metals and their alloys such as steel, stainless steel, lead, aluminum, copper, brass, bronze, Monel (a trademark) metals, nickel zinc, and the like including treated metals such as phos-phatized steel, galvanized steel, and the like; glass; ceramics;
and the like.
The adhesive compositions are applied to substrate sur-faces in a conventional manner such as by dipping spraying, brushing, and the like. Preferably, the substrate surfaces are allowed to dry aftercoating before being brought together. After the sur-faces have been joined, the composite structures are heated in a ;
conventional manner to effect curing of the adhesive compositions and simultaneous vulcanization of the uncured elastomer stock. ;
The following examples are provided for purposes of illustrating the invention, it being understood that the invention is not limited to the examples nor to the specific details therein enumerated. In the examples, amounts are parts by weight unless otherwise specified.
In the several examples, the substrate to which the elastomeric material was bonded was not primed, unless otherwise noted. The composite assembly was cured at conventional conditions of time and temperature for the specific elastomer. The adhesive bond was tested according to ASTM standard D-429, Method B, modified to 45 angle of pull.
The bonded structures are subjected to various tests, in-cluding room temperatures (RT) pull, the boiling water test, and : . . . . .

~S~2~;

the salt s~ray test. In the RT pull test, the rubber b~dy is peeled from the metal at a ~5 angle using a Scott tensile tester -~
and the force required in pounds per :inch is recorded. In the boiling water test, bonded samples, after having been scored at the bond line and prestressed by bending the rubber body back from the metal, are immersed in boiling water for two hours; and in the salt spray test, the samples, after scoring and prestressing, are exposed to a spray of salt solution ~5% sodium chloride) for 48 hours at 100 F. The samples so treated are tested for relative bond strength by pulling the rubber body from the metal.
In the data given in the Examples, failure is expressed in terms of percent of failure in the rubber body, e.g., 95R
means that 95 percent of the failure occurred in the rubber body, with the remaining failure being between the adhesive composition and the metal, or the like.

A series of adhesive compositions containing isocyanato-propyl-triethoxysilane were prepared according to the schedules:
Adhesive A-l A-2 A-3 A-4 Chlorosulfonated polyethylene3535 35 35 Dinitrosobenzene 3030 30 30 Carbon black 4040 40 40 Isocyanatosilane -15 15 15 Polymethylene polyphenyleneisocyanate - - 15 30 Xylene 214214 214 214 In forming the compositions, a masterbatch of adhesive A-l was prepared in a conventional manner. Adhesive formulations A-2, A-3 and A-4 were prepared by blending the respective components into aliquot portions of the masterbatch in a conventional manner.
The thus-formulated adhesive compositions were then coated onto non-primed,grit-blasted, degreased, cold-rolled steel coupons and allowed to dry. The thus~coated steel coupons were ~531~6 placed into contact with a sul~ur vulcanizable natural rubber composition~ Each of the assemblies was cured at 307F for 15 minutes.
Following the vulcanization cycle, the bonded assemblies were tested for environmental resistance according to the boiling water (~ H2O) test. The results are reported in the following table:

~ E~2O Test Adhesive Failure 10 A-l 0 R(Failed in 1-1/4 hrs.) The foregoing data demonstrate that adhesive formulations containing isocyanatosilane compositions have significantly im-proved resistance to degradation from attack by environmental conditions.
EXAMPLE II
A reaction vessel, equipped with an agitation means and maintained at room temperature under a nitrogen atmosphere, was charged with 133 g polymethylene polyphenyleneisocyanate having an average isocyanate functionality of 2.7, 532 g trichloroethy-lene and 0.1 mi dubutyltin dilaurate. The mixture was stirred at room temperature to a uniform consistency. To this mixture there was added, with continuous stirring, 60 g hydroxypropyl-trimethoxy-silane in 240 g trichloroethylene. This addition was accompanied by an immediate mild exotherm of less than 50 C. When the addition of silane-trichloroethylene was completed, the reaction mixture was stirred for an additional 5 minutes and allowed to cool to room temperature. The reaction mixture was a viscous fluid comprising free polymethylene polyphenyleneisocyanateand polymethylene poly-phenyleneisocyanate/hydroxy-propyltrimethoxysilane adduct having a free isocyanate functionality of about 1.7 and a single silane grouping having the structure -NH - C - O - (CH2)3si(O CH3)3 The molar equivalent ratio of total free isocyanate to isocyanato-silane adduct in the reaction mixture was about 2.
EXAMPLE III
Following the procedure of Example II, to a continuously s~irred mixture of 359 g polymethylene polyphenyleneisocyanate : 10 (2.7 NCO functionality) and 1436 g trichloroethylene there was added 193 g methylamino-propyltrimethoxysilane in 772 g benzene to afford a viscous fluid reaction mixture comprising free poly-methylene polyphenyleneisocyanate and poly-methylene polypheny-leneisocyanate/methylaminopropyltrimethoxysilane adduct having a free isocyanate functionality of about 1.7 and a single silane grouping having the structure - NH - C - N ~ (CH2)3 Si (O CH3)3 Tne molar equivalent ratio of total free isocyanate: isocyanato-.
silane adduct in the reaction mixture was about 2.2:1.
EXAMPLE IV
Following the procedure of Example II, to a continuously stirred mixture of 1000 g polymethylene polyphenyleneisocyanate (2.7 NCO functionality) and 100 g trichloroethylene there was added 179 g amino-propyl-trimethoxysilane in 1611 g benzene to afford an amber viscous reaction fluid comprising free polymethy-lene polyphenyleneisocyanate and polymethylene polyphenylene-isocyanate/g-aminopropyltrimethoxysilane isocyanatosilane adduct having a free isocyanate functionality of 1.7 and a single silane grouping having the structure - NH - C - NH ~ (CH2)3 Si (O CH3)3.

~ss~2~

The molar equivalent ratio of total free isocyanate to isocyanato-silane adduct in the reaction mixture was about 8.1:1.
EXAMPLE V
Following the procedure o:E Example II, 179 g g-aminopropyltriethoxy-silane in 1611 g benzene was added to a continuously stirred mixture containing 400 g polymethylene polyphenyleneisocyanate to afford an amber viscous reaction mixture comprising free polymethylene polyphenyleneisocyanate and polymethylene polyphenyleneisocyanate/g-aminopropyltriethoxy-silane isocyanatosilane adduct having a free isocyanate function-ality of 1.7 and a single silane grouping having the structure o - NH - C - NH - (CH2)3 Si (O C2 5 3 The molar equivalent ratio of total free isocyanate to isocyanato-silane adduct in the reaction mixture was about 2.7:1.
EXAMPLE VI
The reaction product of Example II, comprising iso-cyanatosilane adduct, free polymethylene polyphenyleneisocyanate and trichloroethylene, without further treatment, was dip-coated onto a fiberqlass fabric and allowed to dry for 5 hours. The thus-coated fiberglass fabric was then bonded to a polychloro-prene rubber stock of the composition:
Parts by Weight Polychloro~"rene rubber 100 Carbon blac~ 60 Plasticizer 10 Diurethane of tolylene diisocyanate and nitrosophenol 6 polymethylene polyphenyleneisocyanate 3 Calcium oxide 4 The assembly was cured at 320F for 20 minutes. Theadhesion of the cured assembly was evaluated in accordance with ,.. ' ~ ~
:

~s~

the room tem~erature ~ull test, with the following results:
RT Pull Run Coats Lbs. Failure The foregoing data demonstrates that compositions con-taining at least one isocyanatosilane having free isocyanate functionality and at least one polyisocyanate are effective ad-hesives for bonding vulcanizable elastomeric materials to a sub-strate, in this instance, a fiberglass substrate.
EXAMPLE VII
The reaction product of Example IV, comprising isocyanat-osilane adduct having free isocyanate functionality, polymethylene polyphenylene-isocyanate, trichloroethylene and benzene, without further treatment, was used to bond non-primed, grit-blasted, de-greased, cold-rolled steel and fiber-glass fabric to a diurethane-vulcanizable nitrile elastomer stock having the composition:
Parts by Weight Butadiene-acrylonitrile rubber 100 Carbon black 65 Plasticizer ~ 20 Diurethane of tolylene diisocyanate & p-nitrosophenol 6 Polymethylene polyphenyleneisocyanate 6 Zinc dimethyldithiocarbamate 2 The bonded assemblies were cured at 307 F for 20 minutes. The adhesion of the cured assemblies were evaluated in accordance with the room temperature pull test, with the following results:
RT Pull Run Substrate Adhesive CoatsLbs. Failure 1 Steel Control 1 PBH 0 R
1 Steel Example IV 1 120 SB 100 R

~ss~2~
RT Pull Run Substrate Adhesive CoatsLbs. Failure ~ Steel Example IV 1 118 ss 100 R
4 Steel Example IV 2 110 SB 100 R
Steel Example IV 2 125 SB 100 R
6 Fiberglass Control 1 3450 R
7 Fiberglass Control 1 3550 R
8 Fiberglass Example IV 1 76 SB 100 R
9 Fiberglass Example IV 1 76 SB 100 R
Fikerglass Example IV 1 85 SB 100 R
11 Fiberglass Example IV 1 75 SB 100 R
a = Polymethylene polyphenyleneisocyanate @ 10% in trichloroethyl-ene.
b = Pulled by hand, no substantial adhesion.
c = Stoc~ break.
The foregoing data demonstrates the effectiveness of compos-itions containing at least one isocyanatosilane having free isocyanate functionality and at least one free polyisocyanate as adhesive materials for bonding vulcanizable elastomers to sub-strates such as metals and fibers.
EX~MPLE VIII
Following the procedure of Example II, 179 g g-amino-propyl-trimethoxysilane in 716 g benzene was added to a contin-uously stirred mixture of 750 g polymethylene polyphenylene-isocyanate and 750 g trichloroethylene to afford a viscous fluid reaction mixture comprising isocyanatosilane adduct having free isocyanate functionality and free polymethylene polyphenylene-isocyanate, and having a total free isocyanate: adduct equivalent ratio of about 6.6:1.
The thus-prepared reaction mixture, without further treat-ment, was used to bond a polyurethane elastomer containing 12.5 PHR (parts by weight per 100 parts by weight of elastomer) ~s~

4,4'-meth~lene-bis(2-chloroaniline) vulcanizing agent to non-primed, grit-blasted, degreased, cold-rolled steel. For compari-son purposes, the polyurethane elastomer stock was bonded to the metal substrates using the following control adhesive:
Polymethylene polyphenyleneisocyanate @ 25% in trichloroethylene.
Following the vulcanization cycle, the bonded assemblies were tested according to the room temperature pull test by pull-ing at room temperature and at 212F and tested for environmental resistance according to the salt spray test. The results are re-ported in the following tables:
Adhesive: (A) Reaction mixture of Example VIII.
(B) Polymethylene polyphenyleneisocyanate @ 25%
in trichloroethylene.

RT Pull Run Adhesive Lbs.Failure TABLE II
212 F Pull Run Adhesive Lbs.Failure TABLE III

Salt Spray Exposure, Failure Run Adhesive After 72 hrs. After 168 hrs.

Salt Spray Exposure, Failure Run Adhesive After 72 hrs. After 168 hrs.

The foregoing data demonstrate that compositions of the presen~ invention provide adhesive compositions which afford not only strong rubber-to-metal bonds but also substantially im--prove environmental resistance.
EXAMPLE IX
Following the procedure of Example II, 179 g g- amino-propyltrimethoxy silane in 716 g trichloroetnylene was added to a continuously stirred mixture of 750 g polymethylene poly-phenyleneisocyanate and 750 g trichloroethylene. The reaction mixture was diluted with 200 g trichloroethylene, stirred for an additional 5 minutes and cooled to room temperature. The thus-prepared reaction mixture comprising isocyanatosilane adducthaving free isocyanate functionality and free polymethylene polyphenyleneisocyanate and having a total free isocyanate: `
adduct equivalent ratio of about 6.6:1, without further treatment, was divided into several aliquot portions.
Several of the aliquot portions were employed to pre-pare adhesive compositions by combining in a conventional manner the following ingredients (parts by weight):
Adhesive A B C D
Reaction mixture of Example IX100100 100 100 Dinitrosobenzene - 10 20 30 Trichloroethylene 300325350 425 Xylene - 17 34 51 ~ 28 - - -~', ~ .

1~95~

The adhesives were employed to bond non-primed, ~rit-blasted, degreased, cold-rolled steel to sulfur-vulcanizable natural and butyl rubber stocks. Following the vulcanization cycle, the bonded assemblies were tested according to tlle room temperature pull test and for environmental resistance according to tne boiling water test (A H2O). The results are reported in the following table:

RT Pull ~H2O
Elastomer Adhesive Lbs. Failure Failure 1~ Natural rubber A PBH 0 R Not tested Natural rubber B 48 100 R 20 R
2~ R

i~atural rub~er C 53 100 R 55 R
. 3~ ~

Liaiural rubDer . D il 100 R 70 R

Soft natural rubber A PBH 0 R
~oft naiural rubber 3 32 SB 100 R

Soft natural rubber C 30 SB 100 R

Soft natural rub~er D 33 SB 100 R

Butyl rubber A PBH 0 R

3utyl rubber C lOS 100 R

Butyl rubber D 90 SB 90 R
9-, ~0 94 9~ R
EXAkqPLE X
Several of tlle aliquot portions of the reaction mixture of Example IX were employed to prepare adhesive compositions by com~ining in a conventional manner the following ingredients 3~ (parts by weight):
Adhesive B-l B-2 B-3 Reaction mixture, Example IX 100 100 100 3~
Adhesive s-l s-2 s-3 Dinitrosobenzene 30 30 30 Chlorinated ethylene/;?ropylene/
non-conjugated terpolymer35 - -Chlorosulfonated polyethylene - 35 Chloroacrylonitrile/dicnloro~utadiene copolymer - - 35 Tri Cil loroethylene 180 495 437 Xylene 256 151 101 The adhesives were employed to bond to non--primed, yrit-~lasted, degreased, cold-rolled steel sulfur-vulcanizable natural rub~er stoc~. Following the vulcanization cycle, the bonded assemblies were subjected to room temperature pull and boiling water tests witll the following results:

RT Pull~H2O
Adhesive Lbs. Failure Failu_ B-l 53100 R 100 R

EXAMPLE XI
Followiny the procedure of Example II, to a continuously stirred mixture of 750 g polymethylene polyphenyleneisocyanate and 3000 g trichloro-ethylene there was added 179 g g-amino-propyltrimethoxysilane in 716 g trichloroethylene to afford a reaction mixture comprising free polymethylene polyphenylene-isocyanate and polymethylene polyphenyleneisocyanate/g-amino-propyltrimethoxysilane having a free isocyanate functionality of 1.7 and a single silane grouping. The equivalent ratio of total free isocyanate to adduct in the reaction mixture was about 6.6:1.
The reac:tion mixture was separated into several portions ' ;
and adhesive compositions having a total solids content (TSC) of a~out 20 weight percent were prepared as follows, the amounts - 3~ -..

~95~

being parts by ~Jeight:

Parts by Weight Reaction mixture, Example XI100100 100 100 Dinitrosobenzene 30 30 30 30 Chlorinated ethylene/propylene/
non-conjugated diene terpolymer 35 - - -Cnlorosulfonated polyethylene - 35 Chloroacrylonitrile/dichlorobutadiene copolvmer - - 35 Trichloroethylene 400 400 400 400 Xylene 260 260 472 120 Each adhesive was maintained at room temperature for an extended period and viscosity measurements (Broo~field Viscometer, No. 2 spindle at 30 RPM) were made with the following results:
Adi~esive C-l C-2 C C-4 Time Viscosity, CPS
Initial 38 282 250 60 1 wee~ 75 286 292 160 2 weeks 78 320 236 76 203 wee~s - 75 303 192 75 6 weeks 85 360 370 80 The foregoing data demonstrates the excellent ambient temperature storage stability of the herein described adhesive compositions.
EXAMPLE XII
Following the procedure of Example II, 179 g g-amino-propyltrimethoxysllane in 385 g xylene and 358 g trichloroethylene was added to a continuously stirred mixture of 750 g poly-metllylene polyphenyleneisocyanate, 1500 g xylene and 1500 g trichloroethylene to afford a viscous reaction mixture comprising isocyanatosilane adduct llaving free isocyanate functionality and free polymethylene polyphenyleneisocyanate, and having a total ~S~;~6 free isocyanate: adduct equivalent ratio o~ about 6.6:1.
The thus-prepared reaction mixture, without further treatment was employed to prepare adhesive compositions having a total solidscontent of about 15 weight percen-t as follows, amounts being in parts by weight:
Adhesive D-l D-2 D-3 D-~ D-5 Reaction mixture, Example XII 100 100 100100 100 Dinitrosobenzene 30 30 30 30 30 Chlorosulfonated polyethylene - 35 10 Chloroacrylonitrile/dichlorobutadiene copolymer - - 35 Chlorinated ethylene/propylene/non-conjugated diene terpolymer - - - 35 Cellulose acetate butyrate - - - - 35 Xylene 330 220 220168 337 Trichloroethylene 400 715 715777 598 Samples of each adhesive formulation were maintained at room remperature and 130 F for an extended period and viscosity measurements periodically taken with the following results:

Adhesive Viscosity, cps D-l D-2 D-3 D-4 D-5 .
Time: RT 130FRT 130F RT 130FRT130F RT130F

Initial35 35 70 70 115 11590 90140 140 1 week - 46 - 179 - 178 - 180 Paste Paste 2 weeks - 62 ~ 160 - 112 - 44 3 weeks - 92 - 190 - 80 - 30 4 weeks20 190 68 230 130 16540 30

5 weeks25 350 75 172 135 70 55 25

6 weeks - 408 - 138 - 2300 - 45

7 weeks - 850 - 170 - Paste - 25

8 weeks - Paste - ~1000 - 355 - 25

9 weeks - :Paste - 1975 - - 550 - 30 EX~PLE XIII

A series of adhesive formulations were prepared by combining in a conventional manner the following ingredients 3:~6 (parts by weight) Adhesive E-l E~2 E-3 ChlorosulEonated polyethylene 35 35 35 Dinitrosobenzene 30 30 30 Polymethylene polyphenyleneisocyanate 40 - 42 g-Aminopropyltriethoxysilane - 10 Isocyanatosilane(polymethylene poly-phenyleneisocyanate/g-Amino-propyltriethoxysilane adduct) - - 8 Trichloroethylene/xylene @ 50~ 600 600 600 The adhesives were employed to bond sulfur-vulcanizable natural rubber to non-primed, grit-blasted, degreased, cold-rolled steel. Following the vulcanization cycle, the bonded assemblies ~.ere subjected to room temperature pull and boiling water tests with the following results:

RT Pull ~H2O
Adhesive Lbs.Failure Failure E-l 4045 R 0 R (within 10 sec.) E-2 50 0 R 0 R (within 10 sec.) E-3 43100 R 100 R (after 2 hrs.) 100 R (after 6 hrs.) The foregoing data is a comparison of adhesive com~
positions prepared in accordance with this invention versus adhesive compositions containing the starting materials employed to form isocyanatosilane compositions. The data are self-explanatory.
EXAMPLE XIV
Isocyanatosilane adducts were prepared according to the procedure of Example II from g-aminopropyltriethoxysilane and tolylene diisocyanate, methylene-bis(phenyl isocyanate) and methylene-bis(cyclohexylisocyanate), respectively. The re-action mixture in each instance were employed witnout further treatment to form adhesive compositions containing chlorosulfonated polyethylene, dinitrosobenzene and carbon black. The thus prepared adllesive compositions were effective for bonding sulfur-vulcanizable natural rubber stocks to steel substrates, and also formed bonded rubber-to-metal assemblies that were resistant to environmental conditions.

:

. ~ .

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An isocyanatosilane characterized by the presence of at least one reactive isocyanate group and containing a single silane grouping having the structure.

said reactive isocyanate group being connected to said silane grouping through a divalent organic radical having at least one carbon atom, and wherein R is a divalent aliphatic, cycloaliphatic or aromatic radical having from 1 to 20 carbon atoms;
R1 is a monovalent aliphatic, cycloaliphatic or aromatic radical having from 1 to 20 carbon atoms;
R2 is a monovalent aliphatic, cycloaliphatic or aromatic organic radical having from 1 to 8 carbon atoms; and a is zero or 1.

2. An isocyanatosilane compound in accordance with claim 1 wherein R is an alkylene radical having from 1 to 9 carbon atoms; R1 is selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms, cycloalkyl radicals having from 4 to 7 ring carbon atoms, and aryl radicals haying 6, 10, or 14 nuclear carbon atoms; and R2 is selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms, - R3 - O - R4 , and , where R3 is an alkylene group having from 1 to 4 carbon atoms and R4 is an alkyl group having from 1 to 4 carbon atoms.

3. An isocyanatosilane compound in accordance with claim 2 wherein a is zero.

4. An isocyanatosilane compound in accordance with claim 1 which is the reaction product of a polyisocyanate and a primary aminoorganosilane reactant.

5. An isocyanatosilane compound in accordance with claim 2 which is the reaction product of a polyisocyanate and a primary aminoorganosilane reactant.

6. An isocyanatosilane compound in accordance with claim 5 wherein said polyisocyanate has the structural formula wherein R8 is a divalent organic radical having from 1 to 8 carbon atoms; m is 1 or 2; n is a digit having an average value in the range from zero to 15; and X is selected from the group consisting of hydrogen, halogen, alkyl radicals having from 1 to 8 carbon atoms, and alkoxy radicals having from 1 to 8 carbon atoms.

7. An isocyanatosilane according to claim 6 wherein said aminoorganosilane reactant has the formula wherein R is an alkylene radical having from 1 to 9 carbon atoms;
R1 is selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms, cycloalkyl radicals having from 4 to 7 ring carbon atoms, and aryl radicals having 6, 10, or 14 nuclear carbon atoms; and R2 is selected from the group consisting of alkyl radicals having from 1 to 4 carbon atoms, - R3 - O - R4, and , where R3 is an alkylene group having from 1 to 4 carbon atoms and R4 is an alkyl group having from 1 to 4 carbon atoms.

8, An isocyanatosilane according to claim 7 wherein R8 is methylene, X is hydrogen, m is 1 and n has an average value in the range from about 0.1 to about 4.

9. An isocyanatosilane according to claim 8 wherein R
is propylene, R2 is methyl, and a is zero.

10. An isocyanatosilane according to claim 8 wherein R is propylene, R2 is ethyl, and a is zero.

11. An isocyanatosilane according to claim 8 wherein R is propylene, R2 is -CH2CH2 - O - CH3, and a is zero.

12. An isocyanatosilane according to claim 8 wherein R is propylene, R2 is , and a is zero.