EP0904332A1 - Alpha-olefin adhesive compositions - Google Patents

Abstract

An adhesive composition comprises a polymer or copolymer including one of 1) a plurality of C3 or larger alpha-olefin units wherein the polymer has an average number of branch points less than one per alpha-olefin unit; and 2) a plurality of C2 alpha-olefin units wherein the polymer has an average number of branch points greater than 0.01, said adhesive being selected from the group consisting of a pressure sensitive adhesive, a hot melt adhesive, and a polymerized glue. Optionally, the polymer can be crosslinked. Articles of the invention include the adhesive tapes, labels, and adherents comprising a coating of the polymerizable composition of the invention.

Description

ALPHA-OLEFIN ADHESIVE COMPOSITIONS

Field of the Invention

This invention relates to adhesive compositions comprising polymerized alpha-olefin hydrocarbon monomers and methods for preparation and application of the adhesive. Catalysts for the polymerization include organometallic complexes of Group VTII metais (CAS version of the Periodic Table), preferably Pd or Ni.

Background of the Invention

Polymeric adhesives comprising one or more of a variety of polymers are known. Such adhesives are applied to adherends in various ways, the common feature being that the polymer wets the adherend surface. Thus, a polymeric adhesive may be formulated to wet a surface at ambient temperature upon the application of modest pressure, and be classified as a pressure sensitive adhesive. Alternatively, a polymeric adhesive may be formulated to wet a surface at elevated temperatures, so that the adhesive is applied as a hot, molten material or applied as a laminate film by the application of heat and/or pressure to the adhesive while it is in contact with the adherend surface. In still another method of application, an adhesive comprising a monomer or low molecular weight curable oligomer may be applied to an adherend and cured in place. A general description of adhesive materials may be found in Encyclopedia of Polymer Science and Engineering. Vol. 1, "Adhesive Compositions," pages 547-577, Wiley-Interscience Publishers (New York, 1988). Also in this reference is a general description of pressure sensitive adhesives (Encyclopedia of Polymer Science and Engineering. Vol. 13, "Pressure- Sensitive Adhesives," pages 345-368, Wiley-Interscience Publishers (New York, 1988)).

Adhesive polymers are chosen for a variety of properties, including polymer glass transition temperature, thermal stability, and ability to wet and adhere to specific surfaces. Other properties, such as sensitivity to moisture, corrosivity or corrosion resistance, dielectric constant, presence of impurities, color, odor, toxicological properties, processability, etc., may be important for specific applications. Adhesives comprising polymers of alpha-olefin monomers are particularly desirable for adhesion to low-energy surfaces, and in applications where low sensitivity to moisture, low corrosivity, good corrosion resistance, low dielectric constant, low cost and low toxicity are desirable or required.

The use of an oligomer (up to 5000 molecular weight) of an alpha-olefin in thermoplastic hot melt adhesives has been disclosed in U.S. Patent No. 5,512,625. Copolymers of ethylene and linear alpha-olefins are described as adhesives in PCT Patent Application No. WO 93/12151. Radiation curable (crosslinkable) polyolefin pressure sensitive adhesives containing polymers which were prepared under inert conditions using Ziegler-Natta catalysts are disclosed in U.S. Patent No. 5,112,882. Polymerizable adhesives comprising alpha-olefin monomers and Ziegler-Natta or metallocene catalysts wherein polymerization occurs during use have not been described, because these polymerization catalysts are sensitive to oxygen and moisture and require special handling.

Summary of the Invention

Briefly, the present invention describes adhesive compositions comprising a polymer including one of 1) a plurality of C₃ or larger alpha-olefin units wherein the polymer has an average number of branch points less than one per alpha-olefin unit, and 2) a plurality of C₂ alpha-olefin units wherein the polymer has an average number of branch points greater than 0.01, preferably greater than 0.05, most preferably greater than 0.10, per alpha-olefin unit. The invention describes adhesive compositions comprising the polymerization product of a polymerizable composition comprising an alpha-olefin monomer and an effective amount of an organometallic polymerization catalyst comprising a Group VIII metal, preferably Pd or Ni, more preferably Pd. Preferably, the polymer M_w is greater than 5,000, more preferably greater than 90,000 and most preferably greater than 100,000.

In another aspect, the invention provides a method comprising the step of applying the adhesive composition as stated above to at least one adherend surface. More particularly, the invention provides a method of adhering materials using an adhesive composition comprising the polymerization product of a polymerizable composition comprising alpha-olefin monomer and an effective amount of an organometallic polymerization catalyst comprising a Group Vm metal, preferably Pd or Ni, more preferably Pd. Preferably, the polymer M_w is greater than 5,000, more preferably greater than 90,000 and most preferably greater than 100,000.

In a further aspect, the invention describes adhesives comprising a polymerizable composition, the composition comprising at least one Cs or larger alpha-olefin monomer and an effective amount of an organometallic catalyst comprising a Group VIII metal, preferably Pd.

In yet another aspect, the invention describes a method of adhering materials with a polymerizable composition, the composition comprising at least one alpha- olefin monomer having 5 or more carbon atoms (Cs or larger) and an effective amount of an organometallic catalyst comprising a Group VIII metal, preferably Pd.

In some embodiments, the present invention provides adhesives comprising crosslinked alpha-olefin polymers. In one embodiment, a method employing high- energy irradiation of the polymer, preferably by electron beam irradiation, is used. In another embodiment, a method employing ultraviolet (UV) irradiation is used, preferably further comprising the addition of UV-activated crosslinking agents. In yet another embodiment, a method involving thermal crosslinking is used, preferably further comprising the addition of thermally-activated crosslinking agents.

In other embodiments, adhesives comprising mixtures of two or more polymers selected from 1) alpha-olefin polymers comprising a plurality of C3 or larger alpha-olefin units wherein the C3 or larger units are incorporated so as to give a polymer having an average number of branch points less than one per alpha-olefin unit, and 2) polymers comprising a plurality of C₂ alpha-olefin units wherein the polymer has an average number of branch points greater than 0.01, preferably greater than 0.05, most preferably greater than 0.10 per alpha-olefin unit are within the scope of this invention. Preferably, for each polymer the polymer M_w is greater than 5,000, more preferably 90,000, and most preferably greater than 100,000. Adhesives comprising copolymers produced from two or more alpha-olefin monomers or at least one alpha-olefin monomer and one or more non-alpha-olefin monomers are also within the scope of the present invention. In this invention:

"alpha-olefin" and "alpha-olefin hydrocarbon" are equivalent and mean a hydrocarbon containing a double bond in the 1 -position, more particularly, ethylene or a 1 -olefin containing three or more carbon atoms which can be acyclic or cyclic and preferably is an acyclic alpha-olefin; the notation C_x refers to an alpha-olefin which contains x carbon atoms;

"alpha-olefin polymer" means a polymer formed from at least one alpha olefin monomer which, not considering end groups, contains an average of two bonds connecting each monomer unit to other monomer units;

"branch point" means a C unit in the polymer backbone that is bonded to three other carbon atoms, e.g.,

^\

represent units with one and two branch points, respectively;

"steric bulk" means a size large enough and a location in the ligand sufficient to physically block access to non-polymerizing sites on the metal; "alpha-olefin unit" means a group of carbon atoms in a polymer derived by polymerization from a single alpha-olefin molecule;

"high polymer" means a polymer having a weight average molecular weight (M_w), greater than 90,000, and preferably greater than 100,000;

"poly" means two or more; "organometallic catalyst" means a catalyst comprising a Group VHI metal, preferably one of Pd and Ni, a bidentate ligand having steric bulk sufficient to permit formation of polymers, and a metal to R bond, wherein R is H, a hydrocarbyl radical, or a hydrocarbyl radical substituted by at least one alkyl, haloalkyl or aryl group, each group having up to 20 carbon atoms; "polymerizable composition" means a mixture comprising an alpha-olefin monomer and an effective amount of a Group VTJI organometallic catalyst, and optionally at least one of air and water;

"polymerization product" means an alpha-olefin polymer produced by allowing a polymerizable composition to polymerize, optionally containing 0 to 3 percent by weight of metal residues, either as elemental metal or organometallic compounds;

"group" means a chemical species that allows for substitution or which may be substituted by conventional substituents that do not interfere with the desired product;

"Me" means methyl (CH3-);

"Et" means ethyl (CH3CH2-);

"Bu" means butyl; "t-Bu" means tertiary butyl;

"i-Pr" means isopropyl; and "gel fraction" means the fraction of polymer that is insoluble in an appropriate solvent, e.g., toluene, particularly after crosslinking.

Surprisingly, adhesive compositions comprising a polymer including one of 1) an alpha-olefin polymer comprising a plurality of C₃ or larger alpha-olefin units wherein the polymer has an average number of branch points less than one per alpha-olefin unit, and 2) a plurality of C₂ alpha-olefin units wherein the polymer has an average number of branch points greater than 0.01, preferably greater than 0.05, most preferably greater than 0.10 per alpha-olefin unit are useful as adhesives, show different and superior properties when compared to adhesives comprising other alpha-olefin polymers with different branching patterns, such as alpha-olefin polymers comprising a plurality of C₃ or larger alpha-olefin units wherein the polymer has an average number of branch points of about one per alpha-olefin unit, or a plurality of Q. alpha-olefin units wherein the polymer has an average number of branch points less than 0.01 per alpha-olefin unit. The adhesives of the invention comprise polymers that are the polymerization product of a mixture comprising alpha-olefin monomer and an effective amount of a Group VIII organometallic catalyst, preferably Pd or Ni, more preferably Pd. Known alpha-olefin polymers, o

including commercially available alpha-olefin polymers, typically are prepared using known synthetic methods (such as the use of Ziegler-Natta or metallocene catalysis), have structural features, particularly with respect to branching, that can be distinguished from polymers useful in the present invention, and have physical properties, particularly with respect to crystallinity, that can be distinguished from polymers useful in the present invention, even though they are prepared from the same alpha-olefin monomers. A further surprise is that polymerization of the curable adhesives of the invention proceeds in the presence of air and/or water at useful rates to produce adhesives.

Detailed Description of Preferred Embodiments of the Invention

The present invention describes adhesive compositions comprising a polymer including one of 1) an alpha-olefin polymer comprising a plurality of C3 or larger alpha-olefin units wherein the polymer has an average number of branch points less than one per alpha-olefin unit, and 2) a plurality of C₂ alpha-olefin units wherein the polymer has an average number of branch points greater than 0.01, preferably greater than 0.05, most preferably greater than 0.10 per alpha-olefin unit. The adhesives comprise the polymerization product of a polymerizable composition comprising a Cj or larger alpha-olefin monomer and an effective amount of a Group Vπi organometallic catalyst, preferably Pd or Ni. Preferably, the polymer M_w is greater than 5,000, more preferably 90,000, and most preferably greater than 100,000. The invention also describes adhesives comprising a polymerizable composition, the composition comprising at least one alpha-olefin monomer and an effective amount of an organometallic catalyst comprising a Group VIII metal, preferably Pd.

Alpha-olefin hydrocarbon monomers useful in the present invention include substituted and unsubstituted, including acyclic, branched, and cyclic alpha-olefins, wherein substituents on the olefin do not interfere with the polymerization process. Preferred alpha-olefin monomers can have from 2 to about 30 carbon atoms, and include acyclic alpha-olefins such as ethylene, propene, 1 -butene, 1-pentene, 1- hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and the like, and cyclic alpha-olefins such as cyclopentene, and combinations thereof. Most preferably, alpha-olefin monomers include propene, 1 -butene, 1-hexene, 1-octene, and other alpha-olefins up to about C₂₀. In some embodiments, such as adhesives comprising polymerizable compositions, liquid monomers are preferred, and higher boiling alpha-olefins, e.g., 1-pentene and cyclopentene to about 1-octadecene, are particularly preferred. More than one monomer may be useful in polymers and polymerizable compositions of the invention, and copolymers of two or more different monomers are within the scope of this invention. Copolymers may be random or blocky (block copolymers), depending on polymerization kinetics and processes. Useful comonomers include other alpha-olefin hydrocarbons, which may be present in any proportion. Other useful comonomers which are not alpha-olefin hydrocarbons include alkyl acrylates and methacrylates, and acrylic and methacrylic acids and salts thereof. Non-alpha-olefin comonomers are preferably present at no more than 10 mole percent, most preferably at most 5 mole percent of the total polymer composition.

Organometallic catalysts are useful to prepare the polymers used in adhesive compositions of the invention, and to cause polymerization of the monomers present in the polymerizable compositions used in the method of adhering materials. Organometallic catalysts useful for these purposes comprise metals of Periodic Group Viπ, ligands providing steric bulk sufficient to permit formation of polymers, and a metal to R bond, wherein R is H, a hydrocarbyl radical, or a hydrocarbyl radical substituted by at least one of alkyl, haloalkyl or aryl groups. Periodic Group VLII metals include Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, and Pt, and preferred metals are Co, Ni and Pd. Ni and Pd are especially preferred, and Pd is most preferred. Ligands (L) can be selected so that, when they are coordinated to the metal atom, they are of sufficient size so as to block steric access to certain coordination sites on the metal atom. Examples include ArN=C(R¹)C(R^!)=NAr, wherein Ar is 2,6-CβH3(R³)₂, where each R¹ independently can be H or methyl or the two R¹ groups taken together can be 1,8-naphthalene-diyl, and each R³ independently can be methyl, ethyl, isopropyl, or tert-butyl. Without wishing to be bound by theory, it is believed that blocking certain sites may reduce or eliminate processes which result in displacement of the polymer chain from the metal, which prematurely terminates polymerization and results in lower polymer molecular weights. Thus, steric bulk in the ligand permits the formation of high polymer.

Preferred catalysts comprise ligands that are chelating. Chelating means that a ligand molecule contains two or more atoms or groups of atoms that are able to form coordinate links to a central metal atom. Preferred atoms or groups of atoms are two-electron donors, preferably containing nitrogen, more preferably containing an imine

group. Most preferably a chelating ligand comprises two imine groups. Imine groups bearing a substituted or unsubstituted group on the nitrogen are preferred, more preferably such groups are polysubstituted aryl, and most preferably they are 2,6-disubstituted aryl. Substitutents on the aryl ring include alkyl, haloalkyl, and aryl, preferably alkyl, more preferably methyl or isopropyl, and most preferably isopropyl. Catalysts also comprise an atom or group R, defined below, which preferably is H or methyl, most preferably methyl.

Organometallic catalysts useful for preparing polymers for adhesive compositions and in polymerizable compositions useful in the method of the invention can be one-part or two-part. One-part catalysts are organometallic salts of a Group VIII metal complexed with a polydentate ligand having steric bulk sufficient to permit formation of polymer, and an anion selected from the group consisting of B(C«Fs)Λ PF₆ ^~, SbF₆ ^", AsF₆ ^~, BF₄ ^", B{3,5-C6H₃(CF₃)3}4^", (RfSO₂)₂CH^~, (RfSO2)3C^", (RfSO₂)2N^", and RrSO₃ ^", wherein Rf is as defined below, which, when added to monomer, can immediately begin to cause polymer to form, such that no additional reagents or further reactions are necessary to generate an active polymerization catalyst. Such catalysts are advantageous in certain synthetic procedures and methods, particularly when it is desired that a catalyst is to be added to the reaction mixture immediately before polymerization is to begin. For example, such catalysts can be useful in batch reactions used to prepare polymer, or can be usefully added to monomer immediately prior to application of a polymerizable composition to adherend surfaces. One-part catalysts can be isolated and are essentially pure compounds. One-part catalysts are preferably cationic complexes, and further comprise non-coordinating counterions. Preparation of one-part Group VHT metal complexes has been described in

European Patent Application No. 454,231, and by Johnson et al. (J. Am. Chem. Soc, 1995, 117. 6414-6415 and supplementary material), wherein these catalysts were disclosed to be useful in inert atmospheres. The catalysts were characterized as complexes having a cationic portion of the formula LM-R⁺ wherein M is a Group VIII metal, L is a two-electron donor ligand or ligands, as defined above, stabilizing the Group VIII metal, and R is H, a hydrocarbyl radical or a substituted hydrocarbyl radical, wherein the substituting groups can be alkyl (1 to 10 carbon atoms), aryl (5 to 20 carbon atoms), or halogen substituted alkyl. In European Patent Application No. 454,231, M is exemplified as cobalt and a substituted tetraphenylborate anion is described as the counterion. Tetraarylborate with (CF₃) substituents is said to be preferred, and B{3,5-CβH₃(CF₃)₂}4^" is exemplified. In the reference, a preferred cationic portion has the formula

(L^!)₂M-R⁺ wherein the two L^l groups are joined through chemical bonds and each L¹ is a two- electron donor ligand as defined above, and M and R are as previously defined.

Johnson et al. (J. Am. Chem. Soc., 1995, UT, 6414-6415) describe catalysts comprising nickel or palladium complexed with ligand groups chosen to provide steric bulk sufficient to permit formation of polymer. In particular, preferred Pd(II)- and Ni(II)-based catalysts for olefin polymerizations are cationic metal methyl complexes of the general formula

{(ArN=C(R¹)C(R¹)=NAr)M(CH3)(OEt₂)}⁺B{3,5-C6H3(CF3)₂}4^" wherein M is Pd or Ni, Ar is 2,6-C^Α$(t< )₂ where R³ is isopropyl or methyl, and each R¹ independently is H or methyl, or the two R^l groups taken together are 1,8- naphthalene-diyl. A useful catalyst is described as: {((2,6-C₆H₃(i-Pr)₂)N=C(CH3)C(CH₃)=N(2,6-C₆H₃(i-Pr)₂))Pd(CH₃)(Et₂O)}⁺{B(3,5-

Also useful in alpha-olefin polymerizations are compounds of the formula {(ArN=C(R¹)C(R^,)=NAr)Pd(CH2CH2CH2CO2R²)}⁺BAr^,4^' wherein R² can be -CH₃, t-butyl, or -CH2(CF₂)6CF3, as reported by Johnson et al. (J. Am. Chem. Soc, 1996, 118. 267-268 and supplementary material) to be useful in inert atmospheres.

Alternative counterions can provide improved catalysts. One preferred counterion is BζCfFsV. which is safer to prepare than B(3,5-C6H3(CF3)2y, is commercially available from Boulder Scientific Company (Mead, CO) and provides better control over polymer molecular weight. The counterion B(CβFj)4^" is particularly preferred in polymerizable compositions used in the method of adhering materials of the invention. It is also preferred when one-part catalysts are used to prepare polymers useful in the adhesive compositions of the invention, particularly when the polymerization reaction is conducted in the presence of an aqueous phase. Other anions useful as the anionic portion of the catalysts of the present invention may be generally classified as fluorinated (including highly fluorinated and perfluorinated) alkyl- or arylsulfonyl-containing compounds, as represented by Formulae (la) through (Id):

(R_f SO2)2Cir (Rf SO₂)₃C^" (Rf SO₂)2N~ RfSO₃ ^" (la) Ob) (lc) (I<»

wherein each R_f is independently selected from the group consisting of highly fluorinated or perfluorinated alkyl or fluorinated aryl radicals. Compounds of Formulas la, lb and lc may also be cyclic, when a combination of any two Rf groups are linked to form a bridge.

The R_f alkyl chains may contain from 1-20 carbon atoms, with 1-12 carbon atoms preferred. The Rf alkyl chains may be straight, branched, or cyclic and preferably are straight. Heteroatoms or radicals such as divalent non-peroxidic oxygen, trivalent nitrogen or hexavalent sulfur may interrupt the skeletal chain. When Rf is or contains a cyclic structure, such structure preferably has 5 or 6 ring members, 1 or 2 of which can be heteroatoms. The alkyl radical R_f is also free of ethylenic or other carbon-carbon unsaturation: e.g., it is a saturated aliphatic, cycloaiiphatic or heterocyclic radical. By "highly fluorinated" is meant that the degree of fluorination on the chain is sufficient to provide the chain with properties similar to those of a perfluorinated chain. More particularly, a highly fluorinated alkyl group will have more than half the total number of hydrogen atoms on the chain replaced with fluorine atoms. Although hydrogen atoms may remain on the chain, it is preferred that all hydrogen atoms be replaced with fluorine to form a perfluoroalkyl group, and that any hydrogen atoms beyond the at least half replaced with fluorine that are not replaced with fluorine be replaced with bromine and/or chlorine. It is more preferred that at least two out of three hydrogens on the alkyl group be replaced with fluorine, still more preferred that at least three of four hydrogen atoms be replaced with fluorine and most prefeπed that all hydrogen atoms be replaced with fluorine to form a perfluorinated alkyl group.

The fluorinated aryl radicals of Formulas la through Id may contain from 6 to 22 ring carbon atoms, preferably 6 ring carbon atoms, where at least one, and preferably at least two, ring carbon atoms of each aryl radical is substituted with a fluorine atom or a highly fluorinated or perfluorinated alkyl radical as defined above, e.g., CF3.

Examples of anions useful in the practice of the present invention include: (C₂F₅SO₂)₂N-, (C4F₉SO₂)2N~, (OFnSO&C^" (CFsSO&C^" (CF₃SO₂)₂N- (C4F₉SO₂)3C^~ (CF₃SO₂)2(C4F₉SO₂)C^~ (CF₃SO₂)(C4F₉SO₂)N~, {(CF₃)₂NC₂F₄Sθ₂}₂N~, (CF₃)₂NC₂F₄Sθ₂C^"(SO₂CF₃)₂, (3,5-bis(CF3)C6H₃)Sθ2N- SO₂CF₃, CβFjSOzC^" (SO₂CF₃)₂, CβFjSOzN^" SO₂CF₃, CF₃SO₃~ C_gF₁₇SO₃\

^Sθ2CF3 O F N-C₂F₄SO₂N SO₂CF₃ O F N-C₂F₄SO₂C^"(SO₂CF₃)₂

wherein F in the ring means the ring carbon atoms are perfluorinated, and the like. More preferred anions are those described by Formulas lb and lc wherein R_f is a perfluoroalkyl radical having 1-4 carbon atoms.

Anions of this type, and representative syntheses, are described in, e.g., U.S. Patent Nos. 4,505,997, 5,021,308, 4,387,222, 5,072,040, 5,162,177, and 5,273,840, and in Turowsky and Seppelt, Inorg. Chem., l9S8, 27, 2135-2137. {C(SO2CF₃)3}^", {N(SO₂CF₃)₂}^" and {N(SO₂C₂F_s)₂}- are preferred, and {N(SO₂CF₃)₂}^" and {N(SO₂C2Fj)₂}^' are particularly preferred. Such counterions may be preferred with certain metals and ligands, or in some processes. Other useful fluorinated non-coordinating counterions include PFβ^", SbFβ^", AsFβ^", and BF4^".

In the preparation of one-part catalysts, diethyl ether can be useful but it is not preferred because it can be dangerous to store and handle due to its extreme flammability and tendency to form explosive peroxides. Alternative useful ethers are organic compounds containing one ether-type oxygen atom and include tetrahydrofuran and methyl t-butyl ether. Methyl t-butyl ether is particularly preferred.

Preferred catalyst compositions useful in the practice of this invention can be of the formula

{(ArN^CCR^C^^N^Pd^eXether)}^^" wherein Ar and R¹ are as previously defined and ether can be tetrahydrofuran, diethyl ether, or methyl t-butyl ether, and

Q can be selected from B(CβFj)₄, anions as shown in Formulas (la) through (Id), PFβ, SbFβ, AsFβ, and BF4. Particularly preferred are compounds wherein ether is methyl t-butyl ether and Q is selected from B(CβFj)₄ and anions as shown in Formulas la through Id. Examples of preferred one-part catalysts include: {((2_>6-C6H3(i-Pr)2)N=C(CH3)C(CH3)=N(2,6-C₆H3(i-Pr)₂))Pd(CH3)(Me t-butyl etheOrWCβF,)*}-, {((2,6-C«H3(i-Pr)2)N=C(CH3)C(CH3)=N(2,6-CβH3(i-Pr)₂))- Pd(CH₃)(Et₂O)}⁺{B(C₆F_J)4}-,

{((2,6-CβH3(i-Pr)₂)N=C(CH₃)C(CH3)=N(2,6-C6H3(i-Pr)₂))Pd(CH3)

(tetrahydrofuran)}⁺{B(CβF_s)4}^' , {((2,6-C6H₃(i-Pr)2)N=C(CH3)C(CH3)=N(2,6-CβH3(i-Pr)2))Pd(CH₃)(Me t-butyl ether)}⁺{N(SO₂CF₃)2}-, {((2,6-C₆H3(i-Pr)₂)N=C(CH3)C(CH₃)=N(2_>6-C6H3(i-Pr)₂))Pd(CH3)-

(Et₂O)}⁺{N(SO2CF₃)2}^", {((2,6-CβH3(i-Pr)₂)N=C(CH₃)C(CH3)=N(2,6-C6H₃(i-Pr)₂))Pd(CH3)-

(tetrahydrofuran)}⁺{N(SO₂CF₃)2}^*, {((2,6-CβH3(i-Pr)₂)N=C(CH₃)C(CH3)=N(2,6-C6H₃(i-Pr)₂))Pd(CH3)(Me t-butyl ether)}⁺{C (SO₂CF₃)₃}^",

{((2,6-CβH3(i-Pr)2)N-C(CH,)C(CH3)=N(2,6-C6H3(i-Pr)2))Pd(CH3)-

(Et₂O)}⁺{C(SO₂CF,)₃}-, {((2,6-C«H3(i-Pr)2)N-C(CH3)C(CH3)=N(2,6-C«H3(i-Pr)₂))Pd(CH3)-

(tetrahydrofuran)}⁺{C(SO₂CF₃)₃}\ {((2,6-C₆H₃(i-Pr)₂)N=C(CH₃)C(CH₃)=N(2,6-C«H₃(i-Pr)₂))Pd(CH₃)(Me t-butyl {((2,6-CβH3(i-Pr)₂)N=C(CH3)C(CH3)=N(2,6-CβH₃(i-Pr)₂))Pd(CH3)-

(Et₂O)}⁺{N(SO₂C2F₅)2}^", {((2,6-C«H3(i-Pr)₂)N=C(CH3)C(CH3)=N(2,6-CβH₃(i-Pr)₂))Pd(CH3)-

{((2,6-C₆H₃(Me)₂)N=C(CH₃)C(CH3)=N(2,6-C6H₃(Me)₂))Pd(CH₃)(Me t-butyl ether)}⁺{B(C*F_s)4}-, {((2,6-C₆H3(Me)₂)N=C(CH3)C(CH3)=N(2,6-C6H3(Me)2))Pd(CH3)-

(Et₂O)}⁺{B(CβF₅)4}^", {((2,6-CβH₃(Me)2)N=C(CH₃)C(CH3)=N(2,6-CβH3(Me)2))Pd(CH3)-

(tetrahydrofuran)}⁺{B(CβF5)4}^" , {((2,6-CβH3(Me)₂)N=C(CH₃)C(CH3)=N(2,6-CβH3(Me)₂))Pd(CH3)(Me t-butyl ether)}⁺{N(SO2CF₃)2}\ {((2,6-CβH₃(Me)2)N=C(CH3)C(CH3)=N(2,6-CβH3(Me)2))Pd(CH3)-

(Et2θ)}⁺{N(Sθ2CF₃)2}^", {((2,6-CβH₃(Me)₂)N=C(CH₃)C(CH₃)=N(2,6-

CβH₃(Me)₂))Pd(CH₃)(tetrahydrofuran)}⁺{N(SO₂CF₃)₂}-, {((2,6-C«H₃(i-Pr)2)N=C(CH3)C(CH3)=N(2,6-C6H3(i-Pr)₂))Pd(CH3)(Me t-butyl ether)}⁺{N(SO₂CF3)(SO₂C4F₉)}^",

{((2,6-C6H3(i-Pr)₂)N=C(CH3)C(CH3)=N(2,6-C6H₃(i-Pr)2))Pd(CH3)-

(Et2θ)}⁺{N(Sθ2CF₃)(SO₂C4F₉)}^", {((2,6-CβH₃(i-Pr)₂)N=C(CH₃)C(CH3)=N(2_>6-C6H3(i-Pr)₂))Pd(CH3)-

(tetrahydrofuran)}⁺{N(SO₂CF₃)(SO₂C4F₉)}-, {((2,6-C«H₃(i-Pr)₂)N=C(CH₃)C(CH₃)=N(2,6-C₆H₃(i-Pr)₂))Pd(CH3)(Me t-butyl ether)}⁺{BF₄}^', {((2,6-C«H₃(i-Pr)₂)N=C(CH₃)C(CH₃)=N(2,6-C₆H3(i-Pr)₂))Pd(CH3)(Et₂O)}⁺{BF4}-, {((2,6-CβH₃(i-Pr)₂)N=C(CH₃)C(CH₃)=N(2,6-C₆H₃(i-Pr)₂))Pd(CH₃)(Me t-butyl ether)}⁺{CH(SO₂CF₃)2}^", {((2,6-C«H₃(i-Pr)₂)N=C(CH3)C(CH3)=N(2_>6-CβH3(i-Pr)₂))Pd(CH3)- (Et2θ)}⁺{CH(SO₂CF₃)2}\ {((2,6-CeH₃(i-Pr)₂)N=C(CH₃)C(CH₃)=N(2,6-C₆H3(i-Pr)₂))Pd(CH3)(Me t-butyl ether)}⁺{PF₆}^", {((2,6-CβH₃(i-Pr)₂)N=C(CH₃)C(CH₃)=N(2_>6-CβH₃(i-Pr)₂))Pd(CH3)(Et2θ)}⁺{PFβ}-, {((2,6-C₆H₃(i-Pr)₂)N=C(CH₃)C(CH₃)=N(2,6-C₆H₃(i-Pr)₂))Pd(CH3)(Me t-butyl ether)}⁺{SbF₆}\ {((2,6-CβH₃(i-Pr)₂)N=C(CH3)C(CH3)=N(2,6-CβH3(i-Pr)₂))Pd(CH3)(Et₂O)}⁺{SbFβ}-, {((2,6-CβH₃(i-Pr)₂)N=C(CH₃)C(CH3)=N(2,6-CβH3(i-Pr)₂))Pd(CH3)(Me t-butyl ether)}⁺{SO3CF₃}\ {((2,6-CβH₃(i-Pr)₂)N=C(CH₃)C(CH3)=N(2,6-CβH3(i-Pr)₂))Pd(CH₃)- (Et₂O)}⁺{SO₃CF₃}\ {((2,6-C6H₃(i-Pr)₂)N=C(CH3)C(CH3)=N(2,6-CβH3(i-Pr)₂))Pd(CH₃)(Me t-butyl ether)}⁺{SO₃C4F₉}-, {((2,6-CβH₃(i-Pr)2)N=C(CH₃)C(CH₃)=N(2,6-CβH₃(i-Pr)₂))Pd(CH3)- {((2,6-C«H3(i-Pr)₂)N=C(CH3)C(CH3)=N(2,6-C6H3(i-Pr)₂))Pd(CH₃)(Me t-butyl ether)}⁺{NSO2(CF₂)₂SO2}\ and {((2,6-CeH₃(i-Pr)2)N=C(CH₃)C(CH₃)=N(2,6-CeH₃(i-

Pr)2))Pd(CH₃)(Et₂O)}⁺{NSO₂(CF2)2SO2}^".

Two-part catalysts comprise two reagents, a neutral organometallic compound and a cocatalyst salt, that react upon mixing, optionally in the presence of monomer, to yield an active catalyst. Two-part catalysts are particularly advantageous in polymer syntheses when partial mixing of monomer and an organometallic compound is desired (such as to achieve good solubility or suspension) but when it is also desired to initiate polymerization at a later time, for instance, when the second reagent is added. Process advantages resulting from the ability to control the time at which polymerization begins are significant. Two-part catalysts may also allow for the in situ generation of active catalytic compounds which cannot be isolated, and may also be preferred for those situations where the added time and expense of isolating a one-part catalyst are not warranted. Two- part catalysts can be particularly useful in a polymerizable adhesive composition. In particular, the polymerizable composition may comprise two separate portions, a portion A which contains neutral organometallic compound and a portion B which contains cocatalyst salt. Alpha-olefin monomer may be present in one or both of portions A and B. Upon mixing of portions A and B, a polymerizable composition containing active catalyst is generated, which may then be applied to adherend surfaces. In another variation, portion A may be applied to one adherend surface and portion B to another, and mixing is accomplished by bringing the two adherends into contact. Variation of the order and means of mixing are apparent to those skilled in the art. Such latently polymerizable compositions can be supplied as two-package kits. Two-part catalysts preferably comprise a neutral organometallic Pd or Ni compound which includes a ligand or ligands as previously defined, a moiety R which is H, hydrocarbyl radical, or substituted hydrocarbyl radical, and a halogen atom (preferably chlorine), and a cocatalyst. Preferred neutral compounds can be of the general formula

{ArN=C(R¹)C(R¹)=NAr}M(R)X where Ar, R and R¹ are as defined above, and X represents a halogen atom, preferably chlorine or bromine, most preferably chlorine. Examples of preferred neutral compounds include: (2,6-dimethylphenyl)N=C(Me)C(Me)=N(2,6-dimethylphenyl)Pd(Me)Cl,

(2,6-diisopropylphenyl)N=C(Me)C(Me)=N(2,6-diisopropylphenyl)Pd(Me)Cl, (2,6-dimethylphenyl)N=C(H)C(H)=N(2,6-dimethylphenyl)Pd(Me)Cl, (2,6-diisopropylphenyl)N=C(H)C(H)=N(2,6-diisopropylρhenyl)Pd(Me)Cl, (2,6-dimethylphenyl)N=( 1 ,2-acenaphthylene-diyl)=N(2,6- dimethylphenyl)Pd(Me)Cl, wherein 1,2-acenaphthylene-diyl is represented by the structure

S O

(2,6-diisopropylphenyl)N=( 1 ,2-acenaphthylene-diyl)=N(2,6- diisopropylphenyl)Pd(Me)Cl, (2,6-dimethylphenyl)N=C(Me)C(Me)=N(2,6-dimethylphenyl)Ni(Me)Cl,

(2,6-diisopropylphenyl)N=C(Me)C(Me)=N(2,6-diisopropylphenyl)Ni(Me)Cl, (2,6-dimethylphenyl)N=C(H)C(H)=N(2,6-dimethylphenyl)Ni(Me)Cl, (2,6-diisopropylphenyl)N=C(H)C(H)=N(2,6-diisopropylphenyl)Ni(Me)Cl, (2,6-dimethylphenyl)N=(l,2-acenaphthylene-diyl)=N(2,6-dimethylphenyl)Ni(Me)Cl, and

(2,6-diisopropylphenyl)N=( 1 ,2-acenaphthylene-diyl)=N(2,6- diisopropylphenyl)Ni(Me)Cl. Especially preferred neutral compounds include (2,6-dimethylphenyl)N=C(Me)C(Me)=N(2,6-dimethylphenyl)Pd(Me)Cl and (2,6-diisopropylphenyl)N=C(Me)C(Me)=N(2,6-diisopropylphenyl)Pd(Me)Cl. Useful cocatalyst salts are of the general formula

A⁺ Q^" wherein A is selected from silver, thallium, and metals of Periodic Group LA, and Q is selected from B(3,5-CβH₃(CF₃)2)4, B(CβFs)4, anions as shown in Formulas la through Id, PFβ, SbFβ, AsFβ, and BF_4| and solvates and hydrates thereof. For some applications, silver salts are preferred and can have the formulae Ag{B(CeF5)4}(arene)_p and Ag{B(CβH₃(CF₃)₂)₄}(arene)_p wherein arene can be an aromatic hydrocarbon group having 6 to 18 carbon atoms that can be substituted by up to 6 alkyl or aryl groups each having up to 12 carbon atoms, preferably arene can be benzene, toluene, ortho-, meta-, or para-xylene, and mesitylene, and p can be an integer 1, 2, or 3. However, in some applications the less expensive alkali metal salts (Periodic Group 1 A) are preferred. Particular counterions may be preferred under specific reaction conditions. For example, in two-part systems comprising a second aqueous phase, B(CβFs)4 is preferred.

Examples of preferred cocatalyst salts include: Ag⁺{B(CβF₃)4}^"(toluene)₃ , Ag⁺{B(CβF₅)₄}^"(xylene)₃ , Ag⁺{B(3,5-C«H₃(CF3)₂)4}^" (toluene), Li⁺{B(CeFj)₄}^", Na⁺{B(3,5-C₆H3(CF₃)₂)4}^", Li⁺{N(SO₂CF₃)₂}\ Li⁺{B(C«F_s)4}^"(Et₂O)2, Li⁺{N(SO₂CF₃)(SO₂C4F₉)}\ Li⁺{N(SO₂C2F_s)₂}-, Li ⁺{N(SO₂C₂F₃)₂}^"(hydrate), Li ⁺{N(SO₂C₄F₉)₂}^*, Li^* { NSO₂(CF₂)₂SO₂}^",

Ag⁺{C(SO₂CF₃)₃}\ Li⁺{C(SO₂CF₃)₃}^", Ag⁺{CH(SO₂CF₃)₂}\ Li⁺{CH(SO₂CF₃)₂}^", Ag⁺{BF₄}\ Na⁺{BF₄}\ Na⁺{PF₆}^", Ag⁺{PFβ}^", Na⁺{SbF₆}^", Ag⁺{SbF₆}^", Na⁺{AsF₆}\ Ag⁺{AsF₆}\ Ag⁺{SO₃CF₃}^", Na⁺{SO₃CF₃}\ Na⁺{SO₃C4F₉}\ and Still other combinations of catalyst and cocatalyst can be used to prepare polymers useful in adhesive compositions of the invention. Examples of one-part Ni catalysts include

{(2,6-diisopropylphenyl)N=C(Me)C(Me)=N(2,6-diisopropylphenyl)Ni(Me)(Et₂O)}⁺ {(2,6-dimethylphenyl)N=C(H)C(H)=N(2,6-dimethylphenyl)Ni(Me)(Et2θ)}⁺ {B(CβF_s)₄}\ {(2,6-diisopropylphenyl)N=(l,2-acenaphthylene-diyl)=N(2,6- diisopropylphenyl)Ni(Me)(Et₂O)}⁺ {B(C6Fs)4}^*, wherein acenaphthylene- diyl is as above, {(2,6-diisopropylphenyl)N=C(Me)C(Me)=N(2,6-diisopropylphenyl)Ni(Me)(Et₂O)}⁺ {B(3,5-C₆H₃(CF₃)₂)4}-,

{(2,6-dimethylphenyl)N=C(H)C(H)=N(2,6-dimethylphenyl)Ni(Me)(Et₂O)}⁺

{B(3,5-CβH₃(CF₃)₂)4}- and {(2,6-diisopropylphenyl)N=(l,2-acenaphthylene-diyl)=N(2,6- diisopropyIphenyl)Ni(Me)(Et₂O)}⁺ {B(3,5-CβH₃(CF₃)₂)4}^'. Ni catalysts which are generated in situ may also be useful. Preferred are Ni compounds used in combination with aluminum activators containing alkyl groups. Examples of Ni compounds are

(2,6-diisopropylphenyl)N=C(Me)C(Me)=N(2,6-diisopropylphenyl)NiBr2, (2,6-dimethylphenyI)N=C(H)C(H)=N(2,6-dimethylphenyI)NiBr2 and (2,6-diisopropylphenyl)N=(l ,2-acenaphthylene-diyl)=N(2,6- diisopropylphenyI)NiBr₂. Useful aluminum activators include methylaluminoxane (MAO) and Et₂AICl.

Pd and Ni catalysts may be useful for the preparation of polymers comprising one of 1) a plurality of C₃ or larger alpha-olefin units wherein the polymer has an average number of branch points less than one per alpha-olefin unit, and 2) a plurality of C₂ alpha-olefin units wherein the polymer has an average number of branch points greater than 0.01, preferably greater than 0.05, most preferably greater than 0.10, per alpha-olefin unit. These polymers may be prepared under a variety of conditions, including inert conditions, prior to their incorporation into adhesive compositions. Pd catalysts may be preferred for polymer synthesis because they tolerate a wider variety of polymerization process conditions.

Pd one-part and two-part catalysts are preferred in adhesives comprising polymerizable compositions, particularly if the polymerizable composition is to be applied in ambient atmosphere (containing oxygen and variable amounts of moisture). Polyolefins prepared using Pd or Ni catalysts, as synthesized or after additional processing steps, may be in various forms such as powders, microspheres, pellets, blocks or solutions, which can be useful forms for handling the polymers in the preparation of adhesive compositions. One- and two-part catalysts can be present in polymer preparations and polymerizable compositions in the range of 0.0001 to about 20 weight percent, preferably 0.001 to 5 weight percent, most preferably 0.01 to 2 weight percent of the total composition. Polymerization products may contain metal-containing residues, either as elemental metal or as inorganic or organometallic compounds, in the amount 0 to 3 percent by weight of metal. Additional processing may be employed to remove metal residues from late metal polyolefin in the polymerization products. Adjuvants optionally useful in the practice of the invention include solvents such as methylene chloride, and the like.

Additives, adjuvants and fillers as are known in the art can be added to the polymerizable composition of the invention, providing they do not interfere with the intended polymerization process or adversely affect the chemical and physical properties of the resultant adhesive. Additives, adjuvants and fillers can include, but are not limited to, glass or ceramic microspheres or microbubbles, pigments, dyes, or other polymers. Adjuvants may be present in the composition in the range of 0.1 to 90 weight percent. These same adjuvants may be present in adhesive compositions of the invention. It may be advantageous to add adjuvants to monomers prior to polymerization. A wider range of adjuvants, including ones which may adversely affect polymerization, can also be incorporated into adhesive compositions of the invention by mixing into already-formed polymers. Particularly useful additives including tackifying resins, plasticizers, waxes, crystallization accelerators, and oil may be used to modify adhesive properties such as adhesion to various surfaces, adhesion under various conditions, useful temperature range, flexibility, open time, morphology and the like. Examples of such additives include tackifiers such as Escorez™ resins (Exxon Chemical Co., Houston, TX), Wingtack™ resins such as Wingtack Extra™ from Goodyear (Goodyear Tire and Rubber Co., Akron, OH), Piccolyte S25™, Foral AX™, Piccofyn A135™, Piccoiyte SI 5™ and Regalrez 1126™ from Hercules (Hercules, Inc., Wilmington, DE), and Arkon PI 15™ and Arkon P140™ from Arakawa (Arakawa Chemical (USA) Inc., Chicago, LL, for Arakawa Chemical Industries Ltd., Japan), oil such as Shellflex 371™ (Shell Chemical Co., Houston, TX), and waxes such as polyethylene and polypropylene waxes, specifically Vestowax™ (Huls America, Inc., Piscataway, NJ), Epolene™ (Eastman Chemical, Kingsport, TN), and Escomer™ (Exxon Chemical Co., Houston, TX) materials. A large number of resins, waxes, and oils are commercially available from these and other suppliers, and these examples are not intended to be limiting. Relatively acidic organic compounds such as, e.g., phenols and carboxylic acids, can be present in the polymerizable compositions of the invention without deleterious effect on the subsequent polymerization reaction. Thus, polymerizable compositions of alpha-olefin monomer further comprising a hindered phenol-type antioxidant (such as Irganox 1010™, commercially available from Ciba-Geigy Corp., Hawthorne, NJ) are useful in the method of the invention. Hindered phenol- type antioxidants useful in the practice of the invention are well known to those skilled in the art, and are described in Jesse Edenbaum, Plastics Additives and Modifiers Handbook. Van Nostrand Reinhold, New York (1992) pp. 193-207. It is advantageous to add hindered phenol-type antioxidants to polymers to improve polymer performance and aging. It is particularly advantageous to add the antioxidant to liquid monomer. Mixing is easier in monomer than in viscous polymer. It is particularly advantageous to add antioxidant to polymerizable compositions useful in the method of the invention, because it would be difficult or impossible to add antioxidant at a later time in the process. Other antioxidants containing phosphorus, for example, as phosphine or phosphite, are also known as additives in polymers. These secondary antioxidants halt polymerization, and are not usefully added to monomer prior to polymerization (as in polymerizable compositions) but may be usefully added to adhesive composition wherein the polymer is already formed. Sulfur containing compounds such as thiols also halt polymerization, as do strong oxidants such as bleach (sodium hypochlorite). Polymerizations to prepare polymers useful in adhesive compositions of the invention can be conducted at various temperatures. Preferably, the reaction temperature is -78° to +35° C, more preferably -40° to +25° C, and most preferably -10° to +20° C. For reactions conducted in aqueous liquid media, a minimum reaction temperature of about -5° C is preferred. Temperatures above about 40° C may deactivate the catalyst, and good thermal control may be preferred since the polymerization of alpha-olefin monomers is exothermic. It may be particularly advantageous to employ a second aqueous phase as a heat sink to aid in the control of reaction temperature. Polymerizations to provide polymers useful as adhesive compositions of the invention can be conducted at atmospheric pressure and at pressures greater than atmospheric, particularly in cases where one or more of the monomers is a gas. However, to avoid the expense of pressurized reaction vessels, liquid monomers may be preferred. Liquid monomers are preferred in the method of adhering materials with a polymerizable composition. Particularly preferred are monomers with boiling points greater than about 100°C, such as 1-octene and higher alpha- olefin monomers.

The method of adhering materials with a polymerizable composition can be conducted at over a temperature range of -40 to 35°C, preferably -20 to 25°C. Polymerization exotherms may cause some heating during polymerization in the practice of the method, but adherend materials will absorb some of this heat and transport it away. Polymerization rates and temperatures may be controlled by varying the amount of catalyst, with lower catalyst amounts providing slower exotherms and lower overall temperatures. Water can be present in the polymerizable compositions of the method of the invention and during polymerization reactions conducted to make polymers useful in the adhesive compositions of the invention in the range of 0.001 up to 99 weight percent of the total composition. Water may be present in minor amounts when care is not taken to dry the monomer or optional organic solvents. Preferably it is present in naturally-occurring amounts, in monomers as supplied and handled in air. For example, water is soluble in 1-hexene to the extent of approximately 480 parts per million at room temperature, and such concentration is within the scope of the present invention. Monomers are often supplied with varying amounts of water, from 0.001 weight percent up to the maximum solubility of water in the monomer, depending on temperature, specific monomer, ambient humidity, storage conditions, and the like. Optional solvents similarly contain varying amounts of water. Oxygen can be present in an amount of 0.001 to about 2 weight percent or more of the total composition. Monomers and solvents may contain varying amounts of oxygen from the atmosphere depending on temperature, specific monomer or solvent, storage conditions, and the like. Oxygen can also be present in atmospheric amounts in environments surrounding the polymerizable mixture. It is advantageous to avoid the expense and process steps of drying and deoxygenating monomer and solvent. Polymers useful as adhesive compositions of the present invention include alpha-olefin polymers comprising a plurality of C₃ or larger alpha-olefin units wherein the polymer has an average number of branch points less than one per alpha-olefin unit. Without wishing to be bound by theory and recognizing that state-of-the-art analytical techniques are inadequate to determine all structural features, particularly minor ones, it is believed that polymers obtained using catalysts of the invention consist essentially of two types of repeating units: {-CH₂-CHR⁴-}_X and {-(CH₂)„-}_y wherein n is the number of carbon atoms in the alpha-olefin monomer used to make the polymer and R⁴ is {CH3(CH₂)_(n-3)- }■ The number of branched units {-CH₂-CHR⁴-} is less than the total number of monomer units in the polymer, that is, x has a value from 0.01 to 0.99, preferably 0.20 to 0.95, more preferably 0.40 to 0.90, and (x + y) has a value of 0.90 to 1.00. The polymer structure will vary as the monomer or monomers used in the polymerizable composition vary. For example, a polymer made from 1-octene, that is, n = 8, has a structure consisting essentially of {-CH₂-CH(n-hexyl)-}_x and {-(CH₂)β-}_y , wherein x is in the range 0.45 to 0.70, and (x + y) is in the range 0.90 to 0.98. In another example, a polymer made from 1-hexene, that is, n = 6, has a structure consisting essentially of {-CH₂-CH(n-butyl)-}_x and {-(CH₂)β-}_y , wherein x is in the range 0.50 to 0.75, and (x + y) is in the range 0.90 to 0.98. Polymers made from ethylene contain essentially two types of repeating units: {-CH₂-CHR^J-}_P and {-(CH₂)2-}q wherein R⁵ is a linear or branched alkyl group of at least one carbon atom, up to at least 4 carbon atoms, p is at least 0.01, preferably 0.05, most preferably 0.10, and p+q is in the range of 0.90 to 0.98. Current NMR spectroscopic methods are insufficient to determine the maximum value for the number of carbon atoms in R³ which preferably is less than 100. Those skilled in the art will recognize that variations in polymerizable composition, such as the kind and amount of optional solvent or aqueous phase or the catalyst selected and polymerization method can affect the polymer structure. Polymer structure can affect polymer properties, such as crystallinity or modulus. Polyolefins prepared with organometallic Pd or Ni catalysts have physical properties, particularly with respect to crystallinity, that can be distinguished from polymers prepared with Ziegler-Natta or metallocene catalysts. Crystallinity can be detected as a melt transition in differential scanning calorimetry (DSC) analyses of polyolefins. Crystallinity in a given sample depends on sample history, particularly thermal history, and quantitative measurements of the amount of crystallinity are somewhat dependent on measurement technique. Even so, polyolefins prepared with organometallic Pd or Ni catalysts are readily distinguished. For example, polyoctene samples prepared using organometallic Pd catalysts show broad melt transitions with heats of fusion in the range of about 30 to 60 J/g. Polyoctene prepared with Ziegler-Natta catalyst shows little or no detectable melt transition. Similar comparisons can be made for other polyolefins prepared with other monomers. Melt transitions have also been detected for polyolefins made with organometallic Pd and Ni catalysts and alpha-olefin monomers including 1 -butene, 1-pentene, 1-hexene, 1-decene, 1-dodecene, 1-octadecene, and 1-eicosene. Without wishing to be bound by theory, it is believed that the crystallinity observed in polyolefins made with organometallic Pd and Ni catalysts is due to the presence of repeat units {-(CH2),.-} in the polymer backbone (as described above).

For many applications, a high polymer (M_w over 90,000, preferably over 100,000, up to about 10,000,000, preferably up to about 2,000,000) is highly desirable, resulting in improved product performance. High polymers can be obtained by, for instance, an appropriate choice of catalyst-to-monomer ratio. In addition, high polymers can be obtained by continuing the polymerization reaction essentially to completion, that is, consumption of substantially all available monomer. However, in other applications, polymers of lower molecular weight, that is M_w of 5,000 to 90,000 are preferred. Such molecular weights can be achieved by, for instance, an appropriate choice of catalyst-to-monomer ratio, generally higher than that used to achieve high molecular weight polymer (that is, use of more catalyst results in lower molecular weight). In addition, lower molecular weight can be obtained in reactions in which monomer is incompletely converted to polymer, optionally by the addition of reagents which slow or deactivate the catalyst.

Adhesive compositions of the present invention comprise at least one of 1) an alpha-olefin polymer comprising a plurality of C_? or larger alpha-olefin units wherein the polymer has an average number of branch points less than one per alpha-olefin unit, and 2) a plurality of C₂ alpha-olefin units wherein the polymer has an average number of branch points greater than 0.01, preferably greater than 0.05, most preferably greater than 0.10, per alpha-olefin unit. They may further comprise additives, and, in particular, additives include tackifying resins, plasticizers, waxes, crystallization accelerators, and oil may be used to modify adhesive properties such as adhesion to various surfaces, adhesion under various conditions, useful temperature range, flexibility, open time, morphology and the like. Examples of such additives have been noted above.

When the adhesive composition can be applied to adherend surfaces at about -40 to 30°C, with modest pressure (for example, by hand), it is a pressure sensitive adhesive, and is useful in constructions such as tapes and labels. When the adhesive composition is not sticky at about 30°C, but will wet adherend surface at higher temperatures, it is a hot melt adhesive, that is, an adhesive that is useful when applied to adherend surfaces at temperatures above 30°C, generally from about 30 to 400°C, more preferably 40 to 300°C.

The temperature ranges used here to differentiate pressure sensitive adhesives from hot melt adhesives are not intended to be limiting, and, in some cases, these temperature ranges may overlap. Hot melt adhesives are adhesives that are solid in the temperature range required by a given use (usually, but not necessarily, room temperature), but which are applied to the substrates to be joined in the form of a melt (liquid of flowable viscosity), solidifying on cooling after the substrates have been assembled. Pressure sensitive adhesives do not change their physical state from the initial stage of adhesion, i.e., application, to the final breaking of the adhesive bond; they remain permanently deformable, and may alter under even slight application of pressure. By definition, they are adhesives that are permanently tacky as used, typically at room temperature, and that firmly adhere to surfaces upon mere contact. Hot melt adhesives are usefully applied as molten materials, for example, as a bead of molten material delivered through a hot nozzle or "gun" to sheets, films or articles made of wood, metal, or polymer. Hot melt adhesive compositions may also be fabricated into films and applied with heat and/or pressure to adherend surfaces such as in a laminating process. The adhesive composition can also be applied as a polymerizable composition to adherend surfaces. Wetting of the adherend surface occurs at the temperature of application, preferably about -40 to 30°C, and in particular small surface features may be wetted by the polymerizable composition, which generally is of lower viscosity than pressure sensitive adhesive or hot melt adhesive compositions. Polymerizable adhesive compositions are of viscosity of 0.2 to 300,000 centipoise, preferably 0.2 to 100,000 centipoise, depending on amounts and types of additives present (including polymers such as alpha-olefin polymers). Adhesive compositions that are applied as polymerizable compositions are typically described as glues or curable adhesives. The invention describes a method of adhering materials with a polymerizable composition, the composition comprising at least one alpha-olefin monomer and an effective amount of an organometallic catalyst comprising a Group VIII metal, preferably Pd. The method comprises applying the polymerizable composition to at least one adherend surface, and allowing polymerization to occur. The adhesive composition can also be applied to two or more adherend surfaces which are the same or different. Sandwich constructions where the adhesive composition is used to bond two adherends together are also within the scope of the invention.

The invention provides methods of adhering materials with an adhesive composition comprising a polymer including one of 1) a plurality of C₃ or larger alpha-olefin units wherein the polymer has an average number of branch points less than one per alpha-olefin unit, and 2) a plurality of C₂ alpha-olefin units wherein the polymer has an average number of branch points greater than 0.01, preferably greater than 0.05, most preferably greater than 0.10, per alpha-olefin unit, comprising the step of applying the adhesive composition to at least one adherend surface. In one variation, pressure sensitive adhesive compositions are applied to at least one adherend surface at about -40 to 100°C, preferably -40 to 40°C, optionally with pressure, by hand, with the use of an application device, or by machine. In some applications, pressure sensitive adhesives (PSAs) are formulated so that they can also be removed, preferably cleanly, from adherend in a later step. In another variation, hot melt adhesive compositions are applied to at least one adherend surface at about 30 to 400^*C, preferably 40 to 300^*C, optionally with pressure, in forms such as molten beads, drops, powders, or films, with the use of means such as tools or devices with hot zones or nozzles (such as "guns") or by extrusion through a die, or by heating an adhesive plus adherend construction. Other means of delivering hot adhesive materials to adherent surfaces are apparent to those skilled in the art. In another variation, a film comprising a hot melt adhesive composition is placed in contact with at least one adherend surface at an elevated temperature, typically 40 to 40θ"C, optionally with the application of pressure. Particularly useful is the method of applying a polymerizable composition to at least one adherent surface, and allowing polymerization to occur while in contact with the surface(s). By this means, particularly good contact between the polymerizable adhesive composition and the adherend is achieved. Polymerizable adhesive compositions, preferably of a low viscosity in the range of 0.2 to 100,000 centipoise (cP), can be applied as a liquid, preferably at ambient temperature, both to wet the adherend surface and to flow into the crevices and asperities universally found in solid surfaces. A low viscosity provides for better wetting of the substrate to be bonded; this in turn provides for better adhesion. The mechanism of adhesive action known as mechanical interlocking occurs when the substrate surface, upon which the adhesive is spread, contains pores into which the adhesive may flow or projections around which the adhesive solidifies. The adhesive then acts as a mechanical anchor. Physical bonding may result from the penetration of adhesive molecules into the substrate by diffusion. A liquid adhesive may dissolve and diffuse into the substrate material. The extent of diffusion depends upon the affinity of the different types of molecules for one another. The polymerizable adhesive compositions of the invention comprise substantially non-polar liquid hydrocarbon monomers (or mixtures thereof, optionally with additives that do not interfere with the polymerization), which better allows them to wet low surface energy substrates and thereby gain the above- detailed benefits of better wetting and compatibility, without necessarily requiring a pretreatment of the surfaces, although pretreatments may be employed if desired. The polymerizing adhesive compositions of the invention can be used on porous or smooth surfaces.

The present invention provides adhesives comprising crosslinked alpha- olefin polymers. In some applications, a crosslinked adhesive composition provides better product performance. Crosslinking may be accomplished during the polymerization reaction by copolymerization with a polyfunctional monomer, or may be effected by chemical reactions brought about by thermal means or actinic radiation, including high energy sources such as electron beams, gamma radiation, or ultraviolet irradiation, occurring after polymerization. Adhesive compositions comprising crosslinked polymers are within the scope of this invention.

In one embodiment, a method employing high-energy irradiation of the adhesive composition, preferably by electron beam irradiation, is used. Adhesive compositions of the invention can be crosslinked via irradiation with electron beams at dosages preferably in the range of 20 MRad or less, more preferably 10 MRad or less. Advantageously, crosslinked adhesive compositions can be free of added chemical crosslinking agents that might otherwise impair the chemical or physical properties of the adhesive or be disadvantageous in subsequent use, for example, due to color or leaching. Further, electron-beam crosslinking can be carried out after fabrication or other processing of the adhesive composition by, e.g., extrusion, solvent casting, coating, molding, and the like, to give crosslinked constructions such as films. Other useful high-energy sources are known, and are within the scope of the present invention.

In another embodiment, a method employing ultraviolet (UV) irradiation is used, preferably further comprising the addition of at least one UV-activated crosslinking agent. In yet another embodiment, a method involving thermal crosslinking is used, preferably further comprising the addition of at least one thermally-activated crosslinking agent. Preferably, and without wishing to be bound by theory, additives that absorb ultraviolet light and subsequently react to give radicals by homolytic cleavage and/or hydrogen abstraction are mixed with the polymer prior to irradiation. Typical additives include trihaiomethyl-substituted s- triazines (such as 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-l,3,5-triazine), aryl alkyl ketones (such as acetophenone, benzoin ethers, and ketals of benzil), and diaryl ketones (such as benzophenone and anthraquinone). Similarly, additives which thermally generate radicals, such as peroxides, are useful for thermal crosslinking. Other useful additives will be apparent to those skilled in the art and are within the scope of this invention. Crosslinking by ultraviolet irradiation or thermal activation is preferred in certain processes and product constructions, wherein it is necessary to process an uncrosslinked polymer, as in a solution or an extrusion process, to yield forms such as films or fibers, prior to crosslinking.

Adhesive compositions of the invention may be applied and used in various constructions, such as supported or free standing films, as coatings or layers on one or more flexible or rigid backings, as molded or shaped articles, in disposable or recyclable containers or delivery systems or kits such as in tubes or between release liners, as powders or in combinations thereof. Methods of applying the adhesive composition to supports or backings include solvent coating, extrusion, spraying and variations and combinations of these methods. Constructions comprising adhesive compositions of the invention are within the scope of the invention. Useful adherends include metals, fabrics, polymers, especially polyolefins such as high density polyethylene, linear low density polyethylene, low density polyethylene, polypropylene, and other low-surface-energy polymers such as poly(tetrafluoroethylene), and cellulosics such as wood, paper and other wood- derived products such as cardboard.

Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention.

EXAMPLES

All preparations and Examples were conducted in air unless otherwise noted, and reagents were used as supplied and were handled in air, with no attempt to reduce or remove oxygen or water in reagents, solvents or glassware. Solvents used were typical reagent grade, not anhydrous grade. "Ambient temperature" is approximately 23° C. Throughout these examples, the shorthand notation C_z is used to refer to an alpha-olefin containing z carbons. Thus, C₂ is ethylene, C₃ is propylene, Cβ is 1-hexene, Cg is 1-octene, and so on. All chemicals can be obtained from Aldrich Chemical Company (Milwaukee, Wisconsin) unless otherwise noted. Molecular weights were determined by gel-permeation chromatography, referenced to polystyrene standards.

Preparation of Catalysts

Throughout these examples, the material referred to as Pd-A was {(2,6- diisopropylphenyl)N=C(Me)-C(Me)=N(2,6-diisopropylphenyl)}PdMeCl, prepared according to known procedures:

A. Synthesis of ligand (2,6-C«H₃(i-Pr)₂)N=C(CH₃)C(CH₃)=N(2,6- CβHjø-Prtø.

The ligand was prepared according to the procedure described in H. t. Dieck, M. Svoboda, T. Greiser Z. Naturforsch. 36b, 823-832. A mixture of 625 mL methanol, 41.7 g 2,3-butanedione, 171.75 g 2,6-diisopropylaniline and 6.75 g formic acid was prepared in air, then stirred under nitrogen atmosphere at ambient temperature for approximately 18 hr. A yellow precipitate formed, and was collected by filtration. The precipitate was recrystallized from hot ethanol to yield 152.6 gm of {2,6-C«H₃(iPr)₂}N=C(CH₃)C(CH₃)=N{2,6-C6H₃(i-Pr)2}. This ligand was handled and stored in air.

B. Synthesis of (l,5-cyclooctadiene)Pd(Me)CI

The compound was prepared according to the procedure described in R. Rulke, J. M. Ernsting, A. L. Spek, C. . Elsevier, P. W. N. M. van Meeuwen, K. Vήezelnorg. Chem., 1993, 32, 5769-5778. All procedures were conducted in a dry nitrogen atmosphere. The bright yellow solid (l,5-cyclooctadiene)PdCl2, 49.97 g, was placed in 1 L of dry, deoxygenated CH₂CI₂. While stirring, 37.46 g Me₄Sn was added, and the reaction was stirred at ambient temperature for a total of about 4 days. Black solids (presumably Pd metal) formed, and were removed occasionally during this time by filtration through a pad of Fuller's Earth (filter aid). When the reaction solution was a pale yellow, it was filtered once more, and solvent was removed. There was obtained 63.94 g white (l,5-cyclooctadiene)Pd(Me)Cl. This compound was preferably handled in an inert atmosphere.

C. Synthesis of {{2,6-CβH₃(i-Pr)₂}N=C(CH₃)C(CH₃)=N{2,6-C6H3(i-

Pr)₂}}Pd(CH3)Cl, Pd-A.

This neutral organometallic compound was prepared according to the procedure described in L. K.Johnson, C. M. Killian, M. Brookhart J. Am. Chem. Soc, 1995, 117. 6414-6415 and supplementary material. In an inert atmosphere (nitrogen), 31.64 g (l,5-cyclooctadiene)Pd(Me)Cl (synthesis B, above) was placed in 375 mL of dry deoxygenated diethyl ether. The (l,5-cyclooctadiene)Pd(Me)Cl was not completely dissolved. To this mixture was added 48.31 g {2,6-CβH₃(i- Pr)2}N=C(CH₃)C(CH₃)=N{2,6-C6H3(i-Pr)2} (synthesis A, above). An orange precipitate soon formed. The reaction mixture was stirred for about 18 hr, after which 44.11 g { {2,6-C₆H3(i-Pr)₂}N=C(CH₃)C(CH3)=N{2,6-C₆H3(i- Pr)₂} }Pd(CH₃)Cl was collected by filtration. This compound was handled and stored in air.

D. Synthesis and isolation of One-Part Catalyst Described here is the preparation of {(2,6-diisopropylphenyl)N=C(Me)-

C(Me)=N(2,6-diisopropylphenyl)PdMe(methyl t-butyl ether)}⁺ {N(SO₂CF₃)2}^*. A solution of 12.44 g LiN(SO₂CF₃)₂ (HQ115™, commercially available from 3M, St. Paul, MN) and 7.36 g AgNO3 in 350 mL deionized water was stirred with a solution of 22.13 g Pd-A in 350 mL methyl t-butyl ether. A color change was evident within minutes. The ether layer was separated from the water and solids that formed, and washed with a second portion of water, then taken to dryness in vacuo to produce 30.79 g {(2,6-diisopropylphenyl)N=C(Me)- C(Me)=N(2,6-diisopropylphenyl)PdMe(methyl t-butyl ether)}⁺ {N(SO₂CF₃)2}^*, 86 % of theoretical yield. NMR spectroscopy confirmed the identity of this compound.

Similarly, Pd catalysts containing the following counterions were prepared: {C(SO₂CF₃)₃}-, {B{3,5-CβH₃(CF₃)₂}4}\ (SO3C4F₉)\ {N(SO₂C₂F₅)₂}^", and {NSO₂(CF₂)₂SO₂}^". In other preparations, diethyl ether was used in placed of methyl t-butyl ether, and the resulting one-part catalysts then comprised diethyl ether.

Preparation of Polymers

E. Preparation of Polymer Using Two-Part Catalyst

A mixture of 1351 g water, 900 g 1-octene, and a solution of 1.44 g Pd-A in 67 gm CH2CI2 was placed into a large jar. The mixture was cooled to about

0°C, 3.23 g Li{B(CβHj)₄} (Example 1) was added, and the mixture was maintained at 0° to 4° C with shaking. After about 18 hr, a solid plug of polymer filled the container, and the weight yield of polymer after drying in a vacuum oven at 50°C for two days was determined to be 65%. Polymer Analysis: M_w 3.99 x 10⁵, M_» 2.24 x 10⁵. F. Preparation of Polymers

In these preparations, catalyst was mixed with monomer and optional solvent as indicated in Table 1. Polymerization was conducted at the temperature and for the time indicated. All procedures were conducted in air and with no attempt to remove water from monomer or solvent.

In these preparations, one-part catalysts had the formula ({(2,6- CβH3(isopropyl)₂)N=C(Me)C(Me)=N(2,6-C6H3(isopropyl)₂)}Pd(Me)(ether)}⁺Q-, wherein ether and Q are as specified in Table 1, below.

In Table 1, in the column "Rxn Cond," reactions conditions are indicated as follows: A general procedure (indicated by A through D)/reaction temperature in degrees Centigrade/reaction time in hours. Specifics of the procedures are as indicated below.

(A): contained one-part catalyst, and varying amounts of liquid monomer and CH₂CI₂ solvent. In specific procedures, the amounts by weight of monomer to CH₂C1₂ are: A-l, 1 to 1; A-2, 3 to 1; A-4, 7.7 to 1; A-5, 1 to 2; A-6, 3.8 to 1; A-7, 5 portions of each comonomer to 1 portion of CH₂C1₂; and A-8, 5 to 1. Reaction mixture was homogeneous initially, and polymer precipitated in some cases depending on monomer, temperature and extent of reaction. In A-3, one-part catalyst was dissolved in CH₂C1₂ in a pressure vessel and gaseous monomer was added, but the exact amount of monomer charged was not recorded. For the samples where reaction times are shown as unknown, reaction progress was not carefully monitored and reaction times were greater than 100 hours, but not known with certainty.

(B): contained one-part catalyst, 4 portions by weight of ethyl acetate, and 1 portion by weight of monomer. Reaction mixture was initially homogeneous, but polymer soon began to precipitate from solution.

(C): contained two phase (monomer and water) mixture with two-part catalyst, as described in Preparation E.

(D): contained one-part catalyst and monomer, with no solvent. Reaction mixture formed a solution and polymer precipitated from the solution as it formed. Reaction progress was not carefully monitored and reaction times were greater than 100 hours, but not known with certainty. D* contained one-part catalyst and 1 portion by weight of each of two comonomers.

In the column "Mono/Pd" is indicated the amount of monomer in grams, divided by the amount of Pd in moles.

For the last two samples in Table 1, copolymerizations were conducted by mixing the two or more comonomers listed with one-part catalyst in the amounts indicated.

Polymers prepared in this manner, optionally with the removal of solvent, could be used in the preparation of adhesive compositions.

G. Preparation of polymers as microspheres in the presence of an aqueous medium.

In these preparations, polymers were prepared in microsphere form. Polymer microspheres were prepared by mixing deionized water, alpha-olefin monomer, Pd- containing catalyst {((2,6-CβH₃(i-Pr)₂ )N=C(CH3)C(CH₃)=N(2,6-CβHj(i-

Pr)₂))Pd(Me)(Et₂O)}⁺{B(CβFs)₄}^' (Preparation D) dissolved in a small amount of CH₂C1₂ and surfactant, at the temperatures indicated, and allowing the mixtures to remain at that temperature for the indicated times. Polymer microspheres were obtained. The amounts of monomer, water, surfactant and any other additives are indicated in Table 2. The order of mixing was variable; the only significant effect of such variation on laboratory scale preparations which was observed was that addition of solid catalyst to water/monomer mixtures resulted in incomplete delivery of catalyst to the monomer phase, with some catalyst remaining as a third, solid phase. Initial mixing was accomplished by methods such as stirring with a magnetic stir bar (B) or by shaking (S). Some samples were agitated during polymerization as well: intermittently (I) or stirred continuously (C), or not at all (N). Generally, for otherwise similar samples, higher shear rates or increased stirring resulted in smaller microspheres. The microspheres (MS) were examined under a microscope to determine their size, which is indicated as a range of diameters observed under the microscope at 92 times magnification.

In Table 2:

DDSNa is dodecylsulfate, sodium salt.

(not det) means the indicated values were not measured for those particular samples. Wingtack Plus™ is a resin available from Goodyear Tire and Rubber Co., Akron Ohio. It was dissolved in alpha-olefin monomer and this solution was added to other materials in the sample.

ALS is ammonium lauryl sulfate, and the weight indicated is the weight used of a gel of ALS in water, 29% solids, supplied as Stepanol AM-V™ by Stepan Co., Northfield, IL.

Colloidal silica is Nalco 1130™, 30% in water ( Nalco Chemical Co., Naperville, IL)

(ag) indicates that in the sample examined by microscope, the largest spheres appeared be agglomerated with smaller spheres.

In Sample G-10, a two part catalyst was used: 36 mg of ((2,6-CβHs(i- Pr)2)N=C(CH₃)C(CH3)=N(2,6-CβH3(i-Pr)2))Pd(Me)Cl (Preparation C) in 2.210 g CH₂C1₂ was added to 8.032 g 1-octene, and this was added to a mixture of 112 mg Li B(C_<sFj)4 in 12.131 g water. This reaction exothermed in about 6 minutes, and at the elevated temperature the catalyst was deactivated, halting significant further polymerization.

The microspheres in Sample G-2 were dried and the polymer molecular weight was determined to be M_w 341,000, M,, 186,000. The microspheres in Sample G-3 were dried and the polymer molecular weight was determined to be M_w 240,000, M„ 132,000.

Polymers prepared in this manner, optionally dried, could be used in the preparation of adhesive compositions.

H. Preparation of polymer microspheres in the presence of an organic liquid medium.

Polymer microspheres were prepared by mixing organic liquid medium, alpha- olefin monomer, and Pd-containing catalyst {((2,6-CβH₃(i-

Pr)2)N=C(CH₃)C(CH3)=N(2,6-CβH₃(i-Pr)2 ))Pd(Me)(Me t-Bu ether)}⁺{N(SO₂CF₃)₂}^" (Preparation D) at the temperatures indicated, and allowing the mixtures to remain at that temperature for the indicated times. Polymer microspheres formed. The amounts of materials and conditions are indicated in Table 3. Initial mixing was accomplished by methods such as stirring with a magnetic stir bar (B), shaking (S), or mechanically- driven paddle (P). Some samples were agitated during polymerization as well: intermittently (I) or stirred continuously (C), or not at all (N). The microspheres were examined under a microscope to determine their size, and for selected samples the molecular weight of the polymer in the microspheres was also determined. Generally, the lower size microspheres (dimension: diameter) were present in small amounts, having mostly agglomerated to larger irregular shapes of the approximate larger size (dimension: maximum length) indicated. For some samples, portions of the microspheres were collected by filtration, and dried to give powders. 00

Table 3 -4

* methyl ethyl ketone Cfl

** agglomeration was particularly pronounced so the maximum size was not determined (nd) OO -4

In these samples, determination of the largest dimension of the agglomerated microspheres was subjective and should be considered qualitative. The agglomerates were small enough to allow for easy handling and processing, and the microsphere suspensions formed in organic liquid were handled as fluids, by means such as pouring.

Polymer prepared in this manner, with solvent optionally removed, can be used in the preparation of adhesive compositions.

Example 1. Pressure Sensitive Adhesives. Polyoctene used in this example was prepared from 100 g 1-octene in 100 g

CH₂C1₂ using 0.5 g of catalyst {((2,6-CβH3(i-Pr)2)N=C(CH3)C(CH3)-N(2,6-CβH₃(i- Pr)₂))Pd(Me)(Et₂O)}⁺{B(CβF5)4}^" at 0°C for about 2 days, to give polymer of M_w 3.27 x 10^s, M„ 1.76 x 10^s. Polyhexene was prepared similarly, to give polymer of M_w 2.37x 10^s, M„ 1.50 x 10^s. Wingtack Extra™ is a tackifier available from Goodyear (Goodyear Tire and Rubber Co., Akron, Ohio).

Each polymer was dissolved in toluene to give a solution that was 25% by weight polymer. To samples of polymer solution were added materials as indicated in Table 4. Additives were present in the dried coatings at the weight percents indicated, and the remaining weight is polymer. In Sample 1-C, for example, there is 20% by weight of added Wingtack Extra™, and 80% by weight of polyoctene. These solutions were then coated onto 0.025 mm (1 mil) poly(ethylene terephthalate) (PET) film, air dried, then oven dried at 93° C for several minutes. Coating weights were as indicated in the Table. Adhesion of these films to steel was measured at 180° at 30.5 cm/min, according to ASTM D 3330-81 (Method A). Holding power was measured on steel for a 1.27 by 1.27 cm area with a 1 kg weight, according to ASTM D3654-87 (Procedure C).

This example demonstrated that polymers including one or more of a plurality of C3 or larger alpha-olefin units wherein the polymer had an average number of branch points less that one per monomer unit were useful as pressure sensitive adhesives, and that adhesive performance was modified, when desired, by the addition of other materials, such as tackifiers, to the polymer.

Example 2. Pressure Sensitive Adhesives This example demonstrated formulation of pressure sensitive adhesives comprising a polymer including one or more of a plurality of C3 or larger alpha- olefin units wherein the polymer has an average number of branch points less that one per monomer unit. In this example, polymers of 1 -octene were used. Polymer molecular weight varied, and M_w for each polymer was as indicated in Table 5. In Samples 2-A through 2-C, polymer M_n was 1.76 x 10^s. In Samples 2-D through 2- M, polymer M„ was 2.89 x 10^s. Samples were prepared and tested as in Example 1. Additives are commercially available as follows: Wingtack™ Extra from Goodyear (Goodyear Tire and Rubber Co., Akron OH), Piccolyte™ S25, Foral™ AX, Piccofyn™ A135, Piccolyte™ S15 and Regalrez™ 1126 from Hercules (Hercules, Inc., Wilmington, DE), oil (Shellflex™ 371) from Shell (Shell Chemical Co., Houston, TX) and Arkon™ PI 15 from Arakawa (Arakawa Chemical (USA) Inc., Chicago IL, for Arakawa Chemical Industries Ltd., Japan). For the holding power tests, samples were left in place for up to 10,000 min, and an entry of "10,000 +" indicates that the sample had not failed in that time and was not tested for a longer period of time.

Table 5

This example showed that adhesive properties could be varied by changes in formulation. Removal of adhesive from the steel was clean, except in Samples 2-D, 2-E, 2-H and 2-J, where a fog was visible on the steel after removal. In Samples 2- F and 2-H, peel was shocky. For purposes of comparison, a pressure sensitive adhesive comprising a polymer comprising alpha-olefin units wherein the polymer had an average number of branch points of about one per monomer unit (Sample 2- N) was also examined; the polyoctene in Sample 2-N had been prepared using a Ziegler-Natta catalyst (as described in U. S. Patent No. 5,298,708, "Polymers A"), had an M_w of about 700,000, and was coated from a solution of about 7% solids. Note that comparative polymer 2-N showed much poorer shear performance (as measured by holding power) than a similar formulation, Sample 2-M, comprising a polymer including alpha-olefin units wherein the polymer had an average number of branch points less than one per monomer unit. Sample 2-N was a soft adhesive that left a residue upon removal (an undesirable feature), and was the only one of the samples to fail by splitting in the holding power test.

Example 3. Crosslinked Pressure Sensitive Adhesives

Polyoctene and polyhexene were prepared as in Example 1. Solutions were prepared containing 70 parts by weight of polymer, 30 parts by weight of Arkon PI 15 resin (as in Example 2), 0.5 parts by weight of Irganox™ 1010 anti oxidant (Ciba-Geigy, Hawthorne NJ) , in 210 parts toluene and 30 parts xylene. Samples 3- C and 3-D also contained 0.1 part by weight 2-(4-methoxyphenyl)-4,6- bis(trichloromethyl)-l,3,5-triazine (the preparation of which is described in German Patent 1,200,314). Solutions were coated onto PET as in Example 1, at the coating weights indicated. Samples were then subjected to e-beam or ultraviolet irradiation, at the dose as indicated in Table 6. The e-beam source was 175 kilovolt, and Samples 3-A and 3-B were exposed at 762 cm/min. (25 feet/min). UV (high pressure mercury lamp) exposure for Samples 3-C and 3-D was under a nitrogen atmosphere. Adhesive properties were tested using the methods described in Example 1. For holding power tests, a "+" indicates that the sample had not failed in the time indicated, and was not tested for longer times. "Failure mode" describes the type of detachment of the adhesive from the test substrate during the test. "A" indicates adhesive failure, that is, the adhesive separated from the steel test panel. "B" indicates full or partial (as a percentage) separation of the adhesive from the PET backing. "C" indicates cohesive failure, that is, the adhesive material split and was found on both backing (PET) and test substrate (steel) after detachment. The amount of crosslinked polymer was measured as "% Gel," that is, the amount by weight of polymer which was insoluble in toluene. Results are tabulated in Table 6.

This example demonstrated that pressure sensitive adhesives were crosslinked by e- beam or UV irradiation. Certain adhesive properties, such as holding power, were improved by crosslinking.

Example 4. Adhesive Film applied with Heat.

This example demonstrated adhesive films comprising a polymer including one or more of a plurality of C3 or larger alpha-olefin units wherein the polymer had an average number of branch points less than one per monomer unit, and a method of applying such films by the use of heat.

Samples were prepared from polymers including alpha-olefin units wherein the polymer had an average number of branch points less than one per monomer unit, and wherein the alpha-olefin (monomer, indicated by number of carbons, that is, Cι₂ is dodecene, and so on) unit and polymer molecular weights were as indicated in Table 6. Samples of each polymer (formed as a microsphere precipitate from solvent during synthesis and thus in powder form) were pressed between two hot (200 °C) plates with spacers present, to give films of thickness about 0.5 mm ("thickness before" in Table 7). Portions of these films were cut into 2.54 x 2.54 cm (1-inch x 1-inch) squares. The polymer films were then placed at one end of a 2.54 cm wide piece of test substrate, and a second piece of test substrate was placed on top of that, so that 2.54 cm of the second substrate overlapped the film (and first substrate underneath), and the remainder of the second piece extended in the opposite direction of the first piece. The construction of substrate pieces and polymer film was then placed in a 120°C oven for 10 min, with pressure applied by placing a 1 kg weight on the top piece of substrate, above the polymer film. Samples were cooled at ambient temperature, with no weight applied.

With this construction, a square having area 6.45 cm² of polymer was in contact with each piece of substrate, and the substrates could be gripped at opposite ends and pulled apart at a 180° angle. The overlap shear force necessary to break the bond was measured with an Instron Model 1122 (Canton, MA). A 5kN load cell was used. The pieces of substrate were held with 2.54 cm grips on the top and bottom substrates. Samples were pulled apart at 1.27 or 0.127 cm/min, as indicated in Table 7. The stress at break to pull the samples apart was measured in lb and since the area measured was 1 in², this was also the stress at break in psi, as shown in Table 7. Also shown is the conversion to MPa. "Thickness after" in Table 7 was the thickness of the debonded adhesive after testing.

Test substrates were as follows: Stainless steel panels for adhesive testing were 18 gauge, matte finish, deburred, and masked on one side, and measured 5.1 x 12.7 cm with the grain in the long direction. Polymer panels for testing were obtained from Minnesota Plastics (Eden Prairie, MN) and measured 0.95 x 2.54 x 12.7 cm. The following abbreviations are used: SS - stainless steel; HDPE - stress-relieved high density polyethylene; LDPE - low density polyethylene; PP - natural stress-relieved polypropylene; PC - Manchester polycarbonate, general purpose (General Electric GE 9034); AC - clear poly(methylmethacrylate); ABS - natural acrylonitrile-butadiene- styrene polymer; TEF - virgin Teflon. Both sides of the PC and AC panels and one side of the SS panels were masked. These masks were removed prior to testing, and bonding was done using the previously masked sides. No surface pretreatments were employed. Aluminum plates (5054 aluminum, mill finish) were 0.1 cm thick, 10.2 cm long and 2.54 cm wide. Cold rolled steel plates were 0.122 cm thick, 12.7 cm long and 5.1 cm wide. The wood substrate, fir, was 0.813 cm thick, 2.54 cm wide and 10.2 cm long.

VO oo

ro

O

H

Ε 1060 is Eastoflex 1060™ from Eastman Chemical (Kingsport, TN). It is a lower molecular weight polyolefin prepared using a Ziegler- o>

OV 00 Natta catalyst, and showed much poorer adhesive performance than polyoctenes of the invention. w

-4

For all of the polymeric and metal substrates tested, the mode of failure was adhesive, that is, the adhesive film debonded from one substrate rather than tearing. With an acrylic substrate (AC), the film adhered rather poorly, and crept down the substrates rather than suddenly debonding at a high loading. For the wood samples, the polymer film showed variable thickness after debonding, as the polymer took on the shape or contours of the wood surface. Polymer films examined after debonding from wood samples showed wood fibers still sticking to the polymer, indicating that part of the failure mode included removal of wood fibers from the wood substrate.

This example demonstrated that these materials and methods were particularly useful for low surface energy substrates, such as HDPE, LDPE, PP, and Teflon, and were also useful for metals and wood.

Example 5. Adhesives applied as molten materials.

This example illustrated that an adhesive can be made from a polymer including one or more of a plurality of C₃ or larger alpha-olefin units wherein the polymer has an average number of branch points less that one per monomer unit. Good adhesion can be obtained by applying the polymer while it is in a molten state, that is, at an elevated temperature where it flows more readily than at ambient temperature.

Polyoctene of M„ 175,000, M_w 383,000 (as microspheres in powder form, synthesized as described in Preparation H) was added in several portions to a mold maintained at about 160 °C, and it melted to give a molded cylinder of diameter 1.4 cm and length about 14 cm. This "stick" was loaded into a Polygun TC™ , 150 watt, 120 VAC, 60 CPS (3M Adhesives Coatings and Sealers Division, St. Paul MN), which heated the sample and delivered it to through a nozzle (at about 182° to 199° C) as a hot, molten bead to the test substrates. Substrate materials and shapes were as described in Example 4. A hot bead of an approximate "S" shape was applied to the bottom substrate, and a second piece of substrate was immediately applied to the bead and pressed by hand into place. The approximate area of overlap of the substrate pieces was 6.45 cm², and the two pieces extended in opposite directions, in a configuration similar to that in Example 4. The amount and shape of the adhesive bead were difficult to control, but the weight was measured, and the thickness after debonding was also measured. The polymer density (determined from a pressed film of the same polymer) was about 0.94 gm/cm³, and these three values (weight, density and thickness) were used to calculate the irregularly shaped area contact. Samples were tested in an Instron 1122 at 1.27 cm/min, as in Example 4. The force necessary to pull the samples apart and the calculated area of contact were used to calculate the force in psi. The data is shown in Table 8, below. The conversion to MPa is shown.

Table 8

The data in Table 8 show that the calculated force to debond the polymer from the substrate was in the same range as the forces observed in Example 4, for the same polymer and a similar substrate (wood), indicating that there was good wetting of the substrate surface and good adhesion when the polymer was applied in a molten state to the substrate.

Example 6. Preparation and Testing of a Curable Adhesive.

In these trials, 20 mg of catalyst {((2,6-C₆H₃(i-Pr)₂)N=C(CH3)C(CH3)=N(2,6- C6H3(i-Pr)2))Pd(Me)(Et₂O)}⁺{B(C6F5)4}^' (Preparation D) was dissolved in 0.1 g CH2CI2 (to accelerate dissolution) and then 1.0 g of the indicated 1-alkene was added, as shown in Table 8. The mixture was vigorously agitated to give an orange solution. The solution was applied to the bottom test panel at the coverage rate of 6 drops (about 0.3 mL) per 6.45 cm² of overlap. The top test panel was placed over the bottom one to form the overlap joint of the specified area, and was held in place by approximately 122 g (two SS test panels) regardless of the size of the overlap area.

The samples were allowed to cure for 2.5 hours at room temperature (about 23 °C) prior to testing. In other trials, longer cure times (4 hours) did not appreciably change the results.

Test panels were as described in Examples 4. Substrates used in trials shown in

Table 9 were two identical panels, placed to give 2.54 x 5.1 cm overlap for SS, 1.27 x

2.54 cm overlap for LDPE, 2.54 x 2.54 cm overlap for all other substrates. Single overlap shear testing was performed according to ASTM D 1002 - 94 (except as otherwise specified) on the indicated substrates on an Instron Model 1122 with a constant crosshead speed of 0.127 cm/min.

The alpha-olefin monomers used in curable adhesives in this example are indicated in the Table by C_x , where x is the number of carbons in the monomer. The thicknesses of the adhesive polymer films formed between the test panels was 0.05 - 0.175 mm, usually 0.075 - 0.10 mm. The adhesive bond generally failed between the polymer and the top panel, and the failure mode was mostly adhesive with little cohesive failure. Trials were performed similarly for the entries in Table 10, except that two different substrate materials were used. The panels were placed to give an overlap area of 2.54 x 2.54 cm.

The joining ability of this system was further shown by preparing a solution of Pd catalyst and Cg as described above and using 1 drop of the solution to glue together two 0.063 mm thick, 2.54 cm wide strips of Engage 8150™ (ethylene-octene copolymer, Dow Chemical Corp, Midland MI; supplied as a film by Consolidated Thermoplastics Co., Chippewa Falls, WT). Curing conditions were as described above, and the area covered by the cured adhesive was approximately 1.56 cm². In this sample the film elongated and no adhesive bond failure occurred. Upon further manual pulling, the film broke, not the bond.

Example 7. Formulated Hot Melt Adhesives

Polyoctene and polydodecene were prepared in ethyl acetate as described in Preparation H, using the following amounts and conditions. For polyoctene, 100 g 1- octene, 400 g ethyl acetate, and 5.483 g Pd catalyst were kept at 0°C with constant stirring for 3 hr and standing (no agitation) at 0°C for about 15 hr more. 200 mL isopropanol and 0.2 g triphenylphosphite were added to halt polymerization. For polydodecene, 100 g 1-dodecene, 400 g ethyl acetate, and 5.4856 g catalyst were treated similarly. Weight yield of polymer indicated that about 100% of monomer had been converted to polymer. Samples of each polymer and Arkon P140™ (Arakawa Chemical) were mixed at 100°C in a Brabender Plasti-Corder Type EPL-V3302 (Brabender Instruments, Inc., S. Hackensack NJ) in the weight proportions indicated in Table 11, with Irganox™ 1010 added in the amount of 0.4 weight percent of the total composition. In the Formulation column, the proportions are indicated as parts Arkon P140 to parts polymer, with polyoctene or polydodecene indicated as (Cg) or (Cπ), respectively. Thus, 1:2 (Cg) indicates a formulation of one part by weight Arkon PI 40 to 2 parts by weight polyoctene. These formulations were then formed into molded cylinders or sticks, and delivered as a hot bead to test substrates as described in Example 5. The amount of adhesive and force to pull samples apart was measured as in Example 5 at 0.127 cm/min. Failure modes are as described in Example 3 (if there is no entry, the mode of failure was not determined by visual examination).

For some samples, accurate measurement of the thickness of the adhesive after pulling apart, especially in the case of cohesive failure, was difficult. To obtain an estimate of thickness, an average of the thickness measured for other samples was used. However, this number, indicated as "est 0.79" in the thickness column, was only an estimate, and may have been up to 0.18 mm (about 25%) in error. Thus calculated values (contact areas and calculated force per area) using this value were also only estimates. For Samples 7-R through 7-V, the formulation density was not measured, but estimated (with error of about 10%), so again calculated values were estimates.

Polyoctene and polydodecene formulations were also pressed into films as described in Example 4, except that Sample 7-GG was evaluated at 5.1 cm/min. Samples were prepared and evaluated at 0.127 cm/min, as in Example 4. All samples showed cohesive failure. Results are tabulated in Table 12, below.

Table 12

Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth herein.

Claims

OlWe claim:

1. An adhesive composition comprising a polymer including one of 1) a plurality of C3 or larger alpha-olefin units wherein the polymer has an average number of branch points less than one per alpha-olefin unit, and 2) a plurality of C₂ alpha-olefin units wherein the polymer has an average number of branch points greater than 0.01, said adhesive being selected from the group consisting of pressure sensitive adhesives, hot melt adhesives, and polymerized glues, said adhesive composition optionally further comprising one or more additives selected from the group consisting of tackifiers, oils, polymers, antioxidants, and UV- or thermally-activated crosslinking agents, said adhesive composition optionally being crosslinked by high energy irradiation.

2. The adhesive composition according to claim 1 which is crosslinked, optionally by any of UV, thermal, or election beam irradiation.

3. The adhesive composition according to claims 1 or 2 comprising the polymerization product of a polymerizable composition comprising an alpha-olefin monomer and an effective amount of an organometallic polymerization catalyst comprising a Group VIII metal which is complexed with a ligand having steric bulk sufficient to permit formation of a polymer, said adhesive composition optionally having a weight average molecular weight greater than 5,000.

4. The adhesive composition according to any of claims 1 or 3 wherein said alpha-olefin polymer is derived from alpha-olefins selected from the group consisting of ethylene, propene, 1 -butene, 1-pentene, 1 -hexene, 1-heptene, 1 -octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and cyclopentene.

5. The adhesive composition according to any one of claims 1 to 4 which is selected from the group consisting of a free-standing film, a supported film, a coating, and a powder.

6. The adhesive composition according any one of to claims 1 to 5 wherein said Group VIII metal of said catalyst is Pd or Ni.

7. An article comprising a substrate having on at least one surface thereof the adhesive composition according to any one of claims 1 to 6.

8. The article according to claim 7 which is an adhesive tape or label.

9. A method comprising the step of applying the adhesive composition according to any one of claims 1 to 6 at least one adherend surface, said adherend surface optionally being selected from the group consisting of polymers, cellulosics, metals, and fabrics.

10. A polymerizable adhesive composition comprising one or more of Cj or larger alpha-olefin monomers, an effective amount of an organometallic catalyst comprising a Group VIII metal and a polydentate ligand having steric bulk sufficient to permit formation of polymer, said composition having a viscosity in the range of 0.2 to 300,000 centipoise, said polymerizable adhesive composition optionally further comprising an additive selected from the group consisting of tackifiers, oils, antioxidants, and polymers.

11. The polymerizable adhesive composition according to claim 10 which is a glue.

12. The polymerizable adhesive composition according to claims 10 or 11 wherein said catalyst is a one-part catalyst comprising an organometallic salt or a two- part catalyst comprising a neutral organometallic compound and a cocatalyst.

13. A kit for preparing a latently polymerizable adhesive composition according to any one of claims 10 to 12, said composition having component parts capable of being mixed when the composition is to be applied, said kit comprising a combination of a first package containing an amount of an organometallic compound of a two-part catalyst, and a second package comprising a cocatalyst salt of said two- part catalyst, said kit further comprising one or more of alpha-olefin monomers which are present in one or both packages of said kit.

14. A method comprising the steps of 1) applying the polymerizable composition according to any one of claims 10 to 13 to at least one adherend, and 2) allowing polymerization to occur.