EP0563271A1 - Uv/eb curable butyl copolymers for coating applications - Google Patents

Uv/eb curable butyl copolymers for coating applications

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Publication number
EP0563271A1
EP0563271A1 EP92903232A EP92903232A EP0563271A1 EP 0563271 A1 EP0563271 A1 EP 0563271A1 EP 92903232 A EP92903232 A EP 92903232A EP 92903232 A EP92903232 A EP 92903232A EP 0563271 A1 EP0563271 A1 EP 0563271A1
Authority
EP
European Patent Office
Prior art keywords
para
acid
polymer
radiation
alkylstyrene
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP92903232A
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German (de)
English (en)
French (fr)
Inventor
Jay Douglas Audett
Anthony Jay Dias
Kenneth William Powers
Hsien Chang Wang
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ExxonMobil Chemical Patents Inc
Original Assignee
Exxon Chemical Patents Inc
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Publication date
Application filed by Exxon Chemical Patents Inc filed Critical Exxon Chemical Patents Inc
Publication of EP0563271A1 publication Critical patent/EP0563271A1/en
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/038—Macromolecular compounds which are rendered insoluble or differentially wettable
    • G03F7/0388—Macromolecular compounds which are rendered insoluble or differentially wettable with ethylenic or acetylenic bands in the side chains of the photopolymer
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • C08F210/04—Monomers containing three or four carbon atoms
    • C08F210/08—Butenes
    • C08F210/10—Isobutene
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D123/00—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers
    • C09D123/02—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
    • C09D123/18—Homopolymers or copolymers of hydrocarbons having four or more carbon atoms
    • C09D123/20—Homopolymers or copolymers of hydrocarbons having four or more carbon atoms having four to nine carbon atoms
    • C09D123/22—Copolymers of isobutene; Butyl rubber ; Homo- or copolymers of other iso-olefines
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D125/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Coating compositions based on derivatives of such polymers
    • C09D125/02—Homopolymers or copolymers of hydrocarbons
    • C09D125/16—Homopolymers or copolymers of alkyl-substituted styrenes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/038—Macromolecular compounds which are rendered insoluble or differentially wettable
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

  • This invention relates to ultraviolet (UV) and electron beam (EB) reactive functionalized copolymers of an isoolefin and a para-alkylstyrene formulated into coatings or into pressure sensitive adhesives (PSAs) and methods utilizing such coatings or PSAs. More particularly, this invention relates to such copolymers, adhesives and methods wherein the para-alkylstyrene is functionalized to impart radiation curability.
  • UV ultraviolet
  • EB electron beam
  • PSAs and coatings can have highly reactive unsaturation sites in the polymeric backbone to facilitate external free-radical crosslinking, but depending on the polymer, the unsaturation also provides sites at which the backbone can be degraded by reactions involving radicals. Accordingly, it would be desirable to have PSAs and coatings which are curable without the use of these additive compounds and which have saturated polymeric backbones which are not degraded in reactions involving radicals.
  • U. S. Patent 4,556,464 to St. Clair discloses a radiation curable adhesive composition suitable for use as a PSA, comprising a block polymer ABA formulation, where block A is polystyrene/isoprene or polystyrene/butadiene copolymer and block B is polyisoprene, a tackifier compatible with block B and a crosslinking agent compatible with block A.
  • European patent application 17,364 discloses copolymers curable by actinic radiation, such as UV light, made by incorporating from 0.1 to 10 percent by weight of the copolymer of an allyl benzoylbenzoate comonomer with a polymerizable monoethylenically unsaturated comonomer. These polymers are said to be useful in coating and impregnating formulations, and in adhesive, caulk and sealant formulations.
  • U. S. Patent 4,315,998 to Neckers et al. discloses polymeric materials which incorporate photosensitive functionality via a nucleophilic substitution reaction.
  • the polymeric materials serve as a platform for heterogeneous catalysts for a variety of photoinitiated chemical reactions.
  • Cinnamoyl groups are introduced into the polypentenamer, for example, by reacting a polypentenamer having hydroxymethyl groups with cinnamoyl chloride. Relationships involving the photosensitivity of cinnamoylated polypentenamer are discussed.
  • copolymers of styrene and isobutylene are known in the art.
  • copolymers ranging from tough, glassy high polystyrene content copolymers for use in plastic blends, to rubbery low styrene content copolymers for use as impact modifiers, etc. have become well known in this art.
  • Styrene and isobutylene have been copolymerized rather readily in the past under cationic polymerization conditions to yield these copolymers covering the entire compositional range.
  • blocky or random homogeneous copolymers can be produced by altering the copolymerization conditions, such as shown in U. S. Patent 3,948,868 to Powers.
  • This patent thus describes the production of random homogeneous polymers comprising at least two cationically polymerizable monomers such as isobutylene and styrene.
  • This disclosure also includes a lengthy list of various olefinic compounds including isobutylene, styrene, ⁇ -methylstyrene and other such compounds.
  • these compounds have been used in a variety of applications, including use as adhesives in connection with other materials taking advantage of the surface characteristics of the polyisobutylene sequences, as coatings, as asphalt blends, and in various plastic blends.
  • U. S. Patent 3,145,187 to Hankey et al. discloses polymer blends which include a vinyl chloride polymer, a surfactant, and a chlorinated olefin polymer, and the latter is said to include copolymers of various materials which can include isobutylene and styrene, as well as ring-alkyl styrenes, among a large number of other compounds, which olefin polymers can then be chlorinated by known methods.
  • the article fails to recognize any difference between the use of vinyl toluene and para-methylstyrene, and in any event, even when it employs the latter, it employs conditions which result in copolymers having the properties, including heterogeneous compositional distribution and very broad molecular weight distribution for the unfractionated copolymer, as set forth in Tables 4 and 5, which include an M n for the unfractionated copolymer of 16,000, M w /M n of 17.45, and a 4-methylstyrene content in the polymer which varies considerably from the monomer feed and varies significantly as a function of molecular weight.
  • Polymers with a saturated hydrocarbon backbone are well known to possess good environmental and aging resistance which makes them highly desirable in a variety of applications.
  • rubbery copolymers containing major amounts of polyisobutylene are well known to possess low permeability, unique damping properties, and low surface energy which makes them particularly highly desired in many applications.
  • the "inertness" of these saturated hydrocarbon polymers, their low reactivity and incompatibility with most other materials, and the difficulties in adhering them to, or using them in conjunction with most other materials has restricted their use in many areas.
  • thioester thioether, alkoxy, cyanomethyl, hydroxymethyl, thiomethyl, aminomethyl, cationic ionomers (quaternary ammonium or phosphonium, S-isothiouronium, or sulfonium salts), anionic ionomers (sulfonate and carboxylate salts), etc.
  • cationic ionomers quaternary ammonium or phosphonium, S-isothiouronium, or sulfonium salts
  • anionic ionomers sulfonate and carboxylate salts
  • the present invention is, in one aspect, the discovery of an adhesive composition
  • an adhesive composition comprising radiation curable copolymers and a tackifier.
  • radiation curable refers to the vulcanization of the elastomer through exposure to ultraviolet (UV), electron beam (EB), gamma, visible, microwave, and like radiation.
  • the radiation curable copolymer comprises a copolymer of an isoolefin of 4 to 7 carbon atoms and a para-alkylstyrene wherein radiation-reactive functional groups are substituted on the para-alkyl group.
  • the isoolefin comprises isobutylene
  • the para-alkylstyrene comprises para-methylstyrene and/or radiation-curable functionalized para-methylstyrene.
  • the copolymer can be internally crosslinked utilizing UV or EB radiation and consequently requires no photoinitiator reagent or crosslinking promoter.
  • the adhesive compositions are pressure sensitive adhesives (PSAs), i.e. the compositions are tacky at ambient temperatures.
  • PSAs pressure sensitive adhesives
  • These PSA compositions are internally curable by UV or EB radiation, preferably essentially free of added photoinitiator and crosslinking promoter, the presence of which are common problems in the manufacture of the prior art PSA applications.
  • the present PSAs can be applied as hot melt coatings where subsequent vulcanization by radiation crosslinking provides toughness, temperature resistance, solvent resistance, abrasion resistance and resistance to ozone degradation.
  • Yet another aspect of the invention provides a coated article having a surface having coated on at least a portion thereof a radiation curable PSA comprising a copolymer of an isoolefin of 4 to 7 carbon atoms such as isobutylene and a radiation-reactive functionalized para- alkylstyrene such as para-methylstyrene, and optionally, a tackifier.
  • the copolymer has a substantially homogeneous composition.
  • Yet a further aspect of the invention provides a method for making an article coated with a radiation curable PSA which comprises the steps of coating at least a portion of a surface of the article with the radiation curable PSA described above, and exposing the coated article surface to radiation to effect crosslinking of the polymer adhesive.
  • the radiation-reactive functionalized copolymer consists essentially of a radiation-reactive functionalized copolymer of an isoolefin having from 4 to
  • the radiation-reactive functionalized copolymers also preferably have a ratio of weight average molecular weight (M w ) to M n of less than about 6, more preferably less than about 4, most preferably less than about 2.5.
  • the preferred functionalized copolymers employed in the adhesive composition, coating and/or method of the present invention are elastomeric, radiation-reactive functionalized copolymers, comprising between about 45 and 99.5 percent by weight of the isoolefin and between about 0.5 and 55 percent by weight of the para- alkylstyrene and radiation-reactive functionalized para- alkylstyrene.
  • the radiation-reactive functionalized copolymers comprise between about 10 and 99.5 percent by weight of the isoolefin, and between about 0.5 and 90 percent by weight of the para-alkylstyrene and radiation- curable functionalized para-alkylstyrene.
  • the substantially homogeneous radiation-reactive functionalized copolymers employed in the adhesive composition, coating and/or method of the present invention have a number average molecular weight of from about 5000 to about 500,000 or greater, preferably from about 50,000 to about 300,000.
  • the radiation-reactive functionalized copolymers include the para-alkylstyrene having a radiation reactive functional group affixed to the alkyl group as:
  • R and R' are independently selected from hydrogen, alkyl, and the primary and secondary alkyl halides
  • Y is a radiation-reactive functional group or groups joined to the copolymer via ether, ester, amine or other types of chemical bonds. Although they may contain other benzylic functionality as described elsewhere, preferably, these radiation-reactive functionalized copolymers are otherwise substantially free of any additional functional groups in the form of any ring functional groups or any functional groups on the polymer backbone chain (i.e., on the isoolefin carbons).
  • a precursor copolymer of isoolefin having between 4 and 7 carbon atoms and the para-alkylstyrene used for preparation of the radiation functionalized copolymers described above is formed by admixing the isoolefin and the para-alkylstyrene in a copolymerization reactor under copolymerization conditions in the presence of a diluent, and a Lewis acid catalyst, and maintaining the copolymerization reactor substantially free of impurities which can complex with the catalyst or which can copolymerize with the isoolefin or the para-alkylstyrene.
  • precursor copolymers for making the above-described radiation functionalized copolymers are produced as direct reaction products, which, in their as- polymerized form, have a substantially homogeneous compositional distribution, and which can also consist essentially of isoolefin and para-alkylstyrene, and have a number average molecular weight of greater than about 5000.
  • the isobutylene/para-methylstyrene precursor copolymer is insoluble in the preferred diluent, and the process is thus a slurry polymerization process.
  • a solution polymerization process is described.
  • the isobutylene and para-methylstyrene [throughout the remainder of this application the use of applicants' preferred embodiment of isobutylene and para-methylstyrene is intended to also include the potential use of various isoolefins and para-alkylstyrenes (as set forth above)] are present in the precursor copolymer in amounts such that the isobutylene comprises between about 80 and 99.5 percent by weight of the mixture and the para-methylstyrene comprises between about 0.5 and 20 percent by weight of the mixture. In another embodiment, however, the isobutylene comprises from about 10 to 99.5 percent by weight of the mixture and the para- methylstyrene comprises from about 0.5 to about 90 percent by weight of the mixture.
  • the precursor copolymer of the isoolefin and the para-alkylstyrene is then partially selectively brominated to yield a "base terpolymer" containing benzylic bromine functionality.
  • the base terpolymer is produced by selective bromination of one of the benzylic hydrogens of the copolymer of an isoolefin having 4 to 7 carbon atoms and a para-alkylstyrene having the formula:
  • radical initiator is light or heat.
  • radical initiator has a half-life of between about 5 and 2500 minutes, and preferably comprises a bis azo compound.
  • Substitution of radiation-reactive functional groups for the benzylic bromine which is a very active and versatile electrophile can be accomplished by nucleophilic substitution reactions to introduce the desired radiation-reactive functionality, and optionally, one or more additional functionalities.
  • the pendant radiation-reactive functionalized copolymers employed in the composition of the instant invention can be characterized as a radiation reactive, nucleophilically substituted, halogenated copolymer of an isoolefin and para-alkylstyrene which copolymer includes the para-alkylstyrene as:
  • R and R' are independently selected from the group consisting of hydrogen, alkyl, preferably C 1 to C 5 alkyl, and primary or secondary alkyl halides, preferably primary or secondary C 1 to C 5 alkyl halides;
  • X is selected from the group consisting of chlorine and bromine, preferably bromine;
  • Y represents a new radiation-reactive functional group or functional groups, preferably attached to the polymer via nucleophilic substitution of one of the benzylic halogens; and Z represents an optional additional functional group or groups attached to the polymer via nucleophilic substitution of one of the benzylic halogens which may be non-radiation reactive.
  • the coating composition preferably as a pressure sensitive adhesive (PSA) comprises an isobutylene/para- methylstyrene/para-bromomethylstyrene base terpolymer, functionalized with at least one radiation-reactive functional group, and a tackifier.
  • PSA pressure sensitive adhesive
  • the radiation-curable functionalized component is a nucleophilically-substituted halogenated copolymer of an isoolefin and para-alkylstyrene which includes the para- alkylstyrene as:
  • W includes at least Y, and may optionally include a mixture of Y and one or more of hydrogen, X and Z, wherein R, R', X, Y and Z are as defined above.
  • the radiation reactive para-alkylstyrene (wherein W is Y) may comprise from about 0.5 to about 55 weight percent of the radiation reactive copolymer, preferably from about 0.5 to about 20 weight percent, more preferably from about 0.5 to about 15 weight percent, and especially from about 1 to about 7 weight percent of the functionalized copolymer.
  • the unsubstituted para-alkylstyrene (wherein W is hydrogen) may comprise from about 0.5 to about 90 weight percent of the functionalized copolymer, preferably from about 1 to about 20 weight percent and especially from about 2 to about 10 weight percent.
  • the radically halogenated para-alkylstyrene (wherein W is X) may comprise up to about 55 weight percent of the radiation reactive copolymer, preferably less than about 20 weight percent, more preferably less than about 15 weight percent.
  • substantially complete conversion of the halogenated para-alkylstyrene is obtained, for example, by nucleophilic substitution thereof by Y and/or Z groups, so that the radiation- reactive copolymer component of the PSA composition is essentially free of the halogenated para-alkylstyrene preferably comprising less than about 1 weight percent halogenated para-alkylstyrene, more preferably less than about 0.5 weight percent, most preferably less than about 0.1 weight percent and especially less than about 0.02 weight percent.
  • Functionalized para-alkylstyrene may comprise from 0 to about 55 weight percent of the functionalized copolymer, preferably from 0 to about 20 weight percent, more preferably from 0 to about 15 weight percent.
  • the remainder of the radiation reactive copolymer generally comprises the isoolefin which usually ranges from about 10 to about 99.5 weight percent of the radiation reactive copolymer, preferably from about 80 to about 99 percent by weight, more preferably from about 90 to about 98 weight percent.
  • the Mn of the radiation reactive copolymer is from about 5000 to about 500,000, preferably from about 50,000 to about 300,000 and most preferably from about 50,000 to about 150,000.
  • the radiation reactive functionality may be derived from various compounds reactive by actinic or electron beam radiation. These comprise photoinitiators from several different well known categories which can be incorporated into the isobutylene/para-methylstyrene/para-bromomethylstyrene base terpolymer by means of nucleophilic reactions between the benzylic halogen leaving group and the nucleophilic compound containing the photoinitiator moiety.
  • Photoinitiators include: (a) aromatic aldehydes and ketones such as benzophenone, 4-chlorobenzophenone, 4- hydroxybenzophenone, benzoquinone, naphthaquinone, anthraquinone, 2- chloroanthraquinone, benzylidene aceto- phenone, acetophenone, propiophenone, cyclopropyl phenyl ketone, benzaldehyde, ⁇ -napthylphenyl ketone, ⁇ -napthaldehyde, ⁇ -acetonaphthone, 2,3-pentanedione, benzil, fluorenone, benzanthrone,
  • Michler's ketone bis(parahydroxybenzylidene)acetone, benzoin, deoxybenzoin, chlorodeoxybenzoin and the like;
  • alkoxy and acyl substituted aromatic compounds such as 2,2-dimethyloxy-2- phenyl, 1,3,5-triacetyl benzene, 2,5- diethoxy stilbene, and the like;
  • conjugated unsaturated fatty acids such as tung oil acid and derivatives thereof
  • R" is selected from the group consisting of H, CN, and NO 2 ; a and b are 0 or 1; and Ar is an aryl group such as, for example, phenyl, m-nitrophenyl, p- chlorophenyl, acetoxy phenyl, styryl, styryl , phenyl, p-methoxyphenyl, 1- naphthyl, 2-naphthyl, 9-anthryl, 2- furfuryl and 2-thienyl, and may be substituted by one or more additional groups such as, for example, hydrocarbyl, nitro, chloro, alkoxy, azide and sulfonazide (representative examples of these aromatic carboxylic acids include benzoic acid, cinnamic acid, m- nitrocinnamic acid, p-chloro ⁇ innamic acid, p-methoxycinnamic acid, chalcone acrylic acid,
  • nitro aromatic compounds such as, for example, picramide, nitronaphthalene, 5- nitroacenaphthlene, 2-nitrofluorene and the like;
  • dye compounds such as rose bengal, acridine orange, chlorophyllin, crystal violet, eosin Y, fluorescein, flavin aononucleotide, hematoporphyrin, hemin, malachite green, methylene blue, rhodamine B, chlorophyll, cosine, erthrosin, methylene green, toluidine blue, thionine, and the like;
  • dye compounds such as rose bengal, acridine orange, chlorophyllin, crystal violet, eosin Y, fluorescein, flavin aononucleotide, hematoporphyrin, hemin, malachite green, methylene blue, rhodamine B, chlorophyll, cosine, erthrosin, methylene green, toluidine blue, thionine, and the like;
  • azide-containing compounds such as azidobenzene, p-phenylene bisazide, p- azidobenzophenone, 4,4-diazidobenzo- phenone, 4,4'-diazidodiphenylmethane, 4,4'-diazidostilbene, 4,4'-diazidochalcone, 3,6-di(4'-azidobenzal)cyclohexanone, 2,6-di(4'-azidobenzal)-4-methylcyclohexanone, and the like; (k) diazonium salt radicals such as p- diazodiphenylamineparaformaldehyde condensates, 1-diazo-4-dimethylaminobenzene hydrofluoroborate, 1-diazo-3-methyl-4- dimethylaniline sulfate and the like; and
  • (l) multifunctional compounds containing the above photosensitive groups such as 1,2- naphthoquinonediazide, 2,3, 4-trihydroxy- benzophenone, bis-(naphthoquinone-1,2- diazido-5-sulfonate), 2-(naphthoquinone- 1,2-diazido-5-sulfonyloxy)-3-hydroxynaphthalene, naphthoquinone-1,2-diazido-5- sulfonic acid novolak ester, naphthoquinone-1,2-diazido-5-sulfanilide, azidobenzoic acid, azidophthalic acid, and the like; and
  • metal chelate compounds such as benzene chronium tricarbonyl and the like.
  • photoinitiators generally either contain suitable reactive moieties for functionalization of the halogenated isoolefin/para-alkylstyrene base terpolymers via nucleophilic substitution, or can be readily modified to incorporate suitable reactive moieties such as carboxyl radicals or carboxylate salts or esters.
  • crosslink density is a direct function of radiation exposure and the type and concentration of radiation-sensitive functionality. Important variables in determining the type of functionality include the desired degree of functionalization and wavelength of energy absorbance. Also, the photopolymer must generally exhibit good crosslinking response when irradiated in the presence of additional components contained in the coating or PSA formulation, especially tackifiers.
  • the cinnamate derivative photopolymer for example, absorbs high levels of irradiated energy because of its strong absorbance.
  • coating systems incorporating cinnamates as a UV-reactive functionality generally require higher doses of UV irradiation and have shallower crosslink depths. These systems work best with thin coatings, and are particularly desirable in applications wherein crosslinking is to be restricted to an outer layer or shell exposed to the UV radiation.
  • PSAs incorporating benzophenone on the other hand do not absorb as much UV energy because of its weaker absorbances, and they have high hydrogen abstraction reactivity from the photoexcited state. Consequently, coating systems including benzophenone require reduced UV irradiation doses and have greater crosslink depth.
  • Selection of the type of functional group also involves considering the radiation wavelength to be employed to excite the functional group.
  • Those which are reactive to UV wavelengths include cinnamates, benzophenones, thioxanthones, anthraquinones, dithiocarbamates, and the like.
  • naphthoquinone-derivatized photopolymers for example, are sensitive to visible light
  • tung oil acid derivatives are an example of a polymer crosslinkable by high energy radiation such as gamma and electron beam radiation.
  • PSA performance is also dependent upon composition of the polymer backbone, including both the molecular architecture and concentration of para-methylstyrene, i.e., the degree to which the radiation reactive polymer is elastomeric-like (high in isobutylene, low T 8 ) versus the degree to which it is thermoplastic-like (higher in para-methylstyrene, high T 8 ).
  • Increasing para-methylstyrene concentration in the polymer backbone generally contributes to an overall increase in T 8 , and consequently, is a variable for optimization.
  • tack and peel, or adhesion properties are generally favored by low molecular weight
  • shear, or cohesion properties are generally favored by high aolecular weight, some optimization may be desirable.
  • the radiation-curable PSA system of the present invention internalizes photocrosslinking chemistry due to incorporation of a photoinitiator into the molecular structure of the radiation-reactive copolymer component.
  • Such radiation-functionalized copolymer components are derived via selective nucleophilic substitution reactions of base terpolymers comprising isobutylene/para- methylstyrene/para-bromomethylstyrene. They may contain other functionality, are soluble and have a saturated backbone.
  • crosslinking sites in the radiation-functionalized copolymer component of the present invention extend from the pendent functionalized alkylstyryl moieties. Furthermore, these reactive sites also contain radiation-reactive functionality.
  • the benzoylbenzoate derivative undergoes free radical crosslinking under UV exposure.
  • the incorporated benzophenone moiety is a well known photoinitiator in that it reacts with UV radiation to produce a free radical in the enchained benzophenone functionality via a hydrogen abstraction mechanism.
  • N,N-disubstituted dithiocarbamate derivative also undergoes radical crosslinking upon UV exposure.
  • Crosslinking is attributed to the ready ability of the dithiocarbamate ester functionality to form stable radicals under irradiation to permit radical crosslinking and other radical chemistry reactions to occur, rather than backbone cleavage as normally occurs with isobutylene based polymers.
  • Tung oil fatty acid is a fatty acid high in eleostearic acid derived from tung oil and containing conjugated unsaturations. Exposure to electron beam irradiation initiates crosslinking in the tung oil ester functionalized copolymer.
  • the anthraquinone-2-carboxylate ester functionalized copolymer contains the photoinitiator anthraquinone. UV irradiation initiates radical crosslinking.
  • the presence of other functionality is optional and may be either interdispersed on a single functionalized base copolymer with multiple functional groups (of which at least one is radiation-reactive), or two or more functionalized copolymers may be blended together.
  • the presence of the additional functionality enables other desirable properties to be incorporated into a PSA system.
  • the presence of amine functionality in addition to radiation-curable functionality can facilitate water emulsification application of radiation- curable PSAs.
  • the amine derivatives can be used in combination with the benzophenone photoinitiation to provide easily abstracted protons.
  • certain radiation-reactive functional groups act as energy amplifiers and transfer agents for other radiation- reactive groups, thereby allowing for enhanced performance with lower energy absorbance in a wider frequency range.
  • Photoexcitable acroleinium salt functionality present in a coating composition can act as an energy amplification and transfer agent for cinnamate groups which otherwise have a high UV absorbance, low UV transmissivity, and a narrow UV frequency photoinitiation range.
  • the addition of the photoexcitable functionality can allow for greater curing depth, and/or thicker coatings in a cinnamate-based system.
  • the radiation-reactive functionalized copolymer component of the coating includes at least one radiation-reactive functionality so the coating composition is curable by electromagnetic radiation.
  • the photoinitiator By incorporating the photoinitiator directly onto the pendant para-methylstyrene groups randomly dispersed in the polyisobutylene backbone, the polymer can be cured directly by electromagnetic radiation.
  • radiation-curable systems containing a single derivatized copolymer or a blend of several copolymers with at least a single radiation-curable functionality and other functional groups can be tailored PSA systems containing specific functional groups to enhance adhesion to specific substrates, both polar and non-polar categories. For example, the presence of carboxylic acid functionality can enhance aluminum adhesion.
  • the second component of PSA compositions in the present invention is a tackifier suitable for use in UV- or EB-reactive PSAs.
  • Suitable tackifiers include those resins which are compatible with the polymer or polymer blend. Tackifiers are chosen to impart substantial adhesive strength, promote substrate wetting and generally enhance PSA performance, e.g., optimize tack performance versus temperature performance of the cured composition. The tackifier must generally not substantially interfere with the photosensitivity of the UV- or EB-reactive polymer(s) and the ability for gel conversion.
  • Tackifier components suitable for use in this invention include aliphatic and aromatic hydrocarbon resins such as ESCOREZ or WINGTACK 95.
  • WINGTACK 95 is the tradename for a diene-olefin copolymer of piperylene and 2-methyl-2-butene having a softening point of 95oC.
  • the resin is prepared by the cationic polymerization of 60 weight percent piperylene, 10 weight percent isoprene, 5 weight percent cyclopentadiene, 15 weight percent 2-methylbutene and about 10 weight percent dimer. See U. S. Patent 3,577,398.
  • tackifying resins of the same general type may be employed in which the resinous copolymer comprises 20-80 weight percent of piperylene and 80-20 weight percent of 2-methyl-2-butene.
  • adhesion-promoting resins which are also useful in the compositions of this invention include hydrogenated rosins, rosin esters, polyterpenes, terpenephenol resins, and polymerized mixed olefins. Hydrogenated hydrocarbon resins obtained under the trade designation ESCOREZ 5380 and ECR-143H are preferred because unsaturation present in the tackifier may reduce the conversion of polymer to gel through radiation energy absorption or through tackifier participation in crosslinking when the adhesive is cured.
  • tackifiers typically have a ring and ball softening point from about 10oC to about 180oC, preferably from about 15oC to about 75oC.
  • Other hydrocarbon tackifiers obtained from Exxon Chemical Co. under the trade designations ECR-111, and ECR-327 have also been found to be particularly preferred.
  • ECR-143H resin for example, is prepared by the cationic polymerization of a C 5 olefin/diolefin feed stream as described in U. S. Patent 4,916,192 which is hereby incorporated by reference herein.
  • PSA properties are dependent on selection of tackifier resin. Particularly important is the T 8 of the tackifier. Optimization studies show that tack-related properties which are nominally inversely proportional to crosslink density can be improved by obtimizing the T 8 of the PSA system. Selection of tackifier is an important variable in this regard. For example, when ECR-143H and ECR-111 tackifiers were blended together in equal proportions, several tack properties are improved in PSA systems incorporating the blended tackifier over PSA systems incorporating each individual tackifier resin. General tackifier composition is also a strong variable in PSA property optimization. The presence of aromaticity is beneficial for compatibility.
  • PSA systems which are an embodiment of this invention may contain a tackifier resin in an amount offrom about 5 to about 95 parts by weight and the functionalized polymer or polymers having at least one radiation-reactive functional group in an amount of from about 5 to about 95 parts by weight.
  • Preferred PSA systems contain the tackifier in an amount of from about 30 to about 70 parts by weight, and functionalized polymer or polymers having at least one radiation- reactive functional group in an amount of from about 30 to about 70 parts by weight.
  • the adhesive composition may further contain relatively minor amounts of ingredients such as, oils, fillers, coupling agents, colorants, antioxidants, and other stabilizing additives which do not substantially adversely affect the system such as, for example, by adversely interfering with crosslinking or adhesion to a substrate surface.
  • the formulation is preferably a hot-melt essentially free of solvents and other vaporizable constituents which detract from the hot melt characteristics of the formulation, e.g., no need for drying or solvent removal.
  • the antioxidant or stabilizer can be added at from about 0.1 to about 3 percent by weight, preferably from about 0.1 to about 1.5 percent by weight, more preferably from about 0.1 to about 1 percent by weight, and typically at about 0.5 weight percent.
  • the optional oils which may be mentioned include refined hydrocarbon oils typically present in adhesives, including paraffinic, aromatic, and naphthenic oils available under the trade designations KAYDOL (produced by WITCO), TUFFLO (produced by ARCO), and the like.
  • the refined oils serve to reduce viscosity and improve surface tack properties.
  • Particulated fillers which may be used for thickening and price reduction include glass, silica, amorphous SiO 2 , fumed alumina, calcium carbonate, fibers and the like. Suitable commercially available fillers are available under the trade designations CAB-O-SIL, ZEOSIL 35, AEROSIL R972, DUCRAL 10 and the like.
  • Suitable coupling agents include (but are not limited to) organometallic compounds such as, for example, silane-based compounds, organotitanates, organozirconates, organozircoaluminates, chrome complexes and the like. These are generally selected to promote adhesion based on the substrates and/or fillers involved in the particular application.
  • the composition is prepared by blending in the melt until a homogeneous blend is obtained.
  • Typical blending equipment includes, for example, mixing extruders, roll mills, Banbury mixers, Brabenders and the like.
  • the blend components blend easily in the melt and a heated vessel equipped with a stirrer is all that is required.
  • the components are added in no particular order, but generally the tackifying resin is added first and heated in the vessel until molten. Thereafter, the radiation-curable copolymer is placed in the vessel and heated and mixed. Any other optional ingredients are generally added last.
  • the hot melt adhesive may be cooled and later reheated for use, or used directly, e.g. supplied from a reservoir or melt pot to a substrate using conventional equipment, for example, for pumping or pressure extrusion through slot dies.
  • An important feature of the present invention is that the hot melt formulation has a good melt pot stability so that appreciable premature curing of the formulation is not usually encountered at typical hot melt conditions, such as, for example, from about 60oC to about 140oC.
  • the hot melt is heated sufficiently for a target viscosity of about 100,000 cps, although a viscosity as high as 150,000 cps can usually be tolerated.
  • the viscosity of the hot melt should not increase more than 20 percent when maintained at the pot temperature for a period of 8 hours.
  • the adhesive compositions of the present invention may also be applied to the substrate from a solution of up to about 40 percent weight solids of the ingredients in a solvent such as toluene, the solvent being removed by evaporation prior to crosslinking by exposure to the radiation.
  • a solvent such as toluene
  • the ingredients may be mixed in a solvent, the mixture may be emulsified and the solvent evaporated, and the adhesive may be applied to the substrate as 50-60 percent weight solids emulsion, the water being removed by evaporation with conventional drying equipment and techniques prior to crosslinking.
  • compositions of the present invention can be cured by exposure to high energy electromagnetic radiation such as electron beam radiation or ultraviolet radiation.
  • the electron beam radiation or high energy ionizing radiation which is employed to effect the crosslinking reaction can be obtained from any suitable source such as an atomic pile, a resonant transformer accelerator, a Van de Graaf electron accelerator, a Linac electron accelerator, a betatron, a synchrotron, a cyclotron, or the like. Radiation from these sources will produce ionizing radiation such as electrons, protons, neutrons, deuterons, gamma rays. X-rays, ⁇ -particles and ⁇ -particles.
  • the crosslinking reaction is conveniently effected at room temperature, but it can be conducted at depressed or elevated temperatures if desired. It is also within the spirit and scope of the invention to effect the crosslinking reaction within the confines of an inert atmosphere to prevent air inhibition of the crosslinking reaction and to prevent oxidative degradation of the polymer.
  • the amount and kind of radiation required depends primarily on the type and amount of radiation sensitive functionality employed, and the level of curing desired. Suitable doses of EB radiation include from about 0.2 megarad to about 20 megarad, preferably from about 1 megarad to about 10 megarad.
  • Suitable UV radiation doses are those received by passing under a medium pressure mercury lamp rated at 200 watts per square inch at line speeds of about 5 to about 800 feet per minute, but preferably from about 20 to about 400 feet per minute.
  • a preferred use of the present invention is in the preparation of pressure-sensitive adhesive tapes or in the manufacture of labels.
  • the pressure-sensitive adhesive tape comprises a flexible backing sheet and a layer of the adhesive composition of the novel PSA compound coated on one major surface of the backing sheet.
  • the backing sheet may be a plastic film, paper or any other suitable material and the tape may include various other layers or coatings, such as primers, release coatings and the like, which are used in the manufacture of pressure-sensitive tapes.
  • radiation reactive functionalized copolymer of the present invention include sealants and caulks which are applied at low viscosity and cured by exposure to UV or EB radiation, as negative photoresists, or other coating or lithographic applications where properties such as resistance to temperature solvents corrosion and abrasion are improved by radiation crosslinking.
  • PSA formulations crosslinked through UV or EB exposure are improved cohesive strength, shear adhesion failure temperatures, and resistance to abrasion and solvents. Sealants or caulks acquire improved weatherability and temperature resistance.
  • PSA materials comprising a polyisobutene polymer incorporating phenyl rings is a polymer backbone free of unsaturations. These unsaturations are typically highly reactive sites for ozone degradation which generally occurs in elastomers comprising isoprene. These sites are also liable to be weak points during any free-radical crosslinking cure process.
  • the presence of the phenyl rings enhances the UV resistance to degradation of the polyisobutene backbone.
  • General aging and weathering properties are improved as compared to other radiation crosslinked elastomers, such as natural rubber or Kraton 1320X.
  • UV reactive PSA systems which are an embodiment of the present invention arises from internal ization of the photoinitiating reagent for a photocycloaddition or a free radical crosslinking mechanism into the polymer molecule.
  • This innovation eliminates additaments such as photoinitiators and crosslinking promoters which are otherwise necessary to cure PSA systems by free-radical mechanisms. Volatility and toxicity of added photoinitiators and promoters are common problems generally associated with radiation processing.
  • the present invention also provides useful coated articles or sheets , and a method by which they may be prepared utilizing the tack properties of the PSA systems and the UV or EB radiation curability described previously.
  • a coating of these PSAs can be applied to a surface of articles or sheets as a hot melt or in solution in thin, low viscosity layers .
  • the article or sheet can be exposed to radiation to effect crosslinking reactions in the coating.
  • the coating is particularly useful as a pressure-sensitive adhesive tape or label with enhanced properties .
  • Additional embodiments of the present invention include useful coated articles , including articles having corrosion barrier coatings, lithographic images, and the like utilizing the radiation-reactive functionalized copolymers of isobutylene and para-methylstyrene, and a method by which these articles may be made, ⁇ coating of these photopolymers can be applied to a surface of an article as a hot melt or in solution in thin low viscosity layers.
  • the articles can be exposed to UV or EB or other kinds of high energy electromagnetic radiation to effect crosslinking reactions in the coatings.
  • a mask is placed over the article coated with the radiation-reactive functionalized copolymer. Exposure to suitable radiation selectively crosslinks the coating not shielded by the masking object. Developing with a suitable solvent removes the uncrosslinked coating leaving an image. D. Preparation of the Radiation-Functionalized
  • This invention is, in part, based upon the discovery that the polymerization of isoolefin and para- alkylstyrene under certain specific polymerization conditions now permits one to produce radiation- functionalizable (via halogenation and nucleophilic substitution) precursor copolymers which comprise the direct reaction product (that is, in their as-polymerized form) , and which have unexpectedly homogeneous uniform compositional distributions.
  • the polymeric backbones , or precursor copolymers of the novel functionalized copolymers employed in the adhesive compositions of the present invention can be produced.
  • copolymers including the radiation-reactive copolymers, as evaluated by gel permeation chromatography
  • GPC demonstrate narrow molecular weight distributions and substantially homogeneous compositional distributions, or compositional uniformity over the entire range of compositions thereof.
  • at least about 95 percent by weight of the precursor copolymer product has a para-alkylstyrene content within about 10 percent by weight, and preferably within about 7 percent by weight, of the average para-alkylstyrene content for the overall composition
  • at least about 97 percent by weight of the copolymer product has a para-alkylstyrene content within about 10 percent by weight, and preferably within about 7 percent by weight, of the average para-alkylstyrene content for the overall composition.
  • these precursor copolymers are essentially random copolymers, and in any particular polymer chain the para-alkylstyrene and isoolefin units will be essentially randomly distributed throughout that chain.
  • the properties of these precursor copolymers leads to a number of distinct advantages over the prior art, including the ability to produce useful functionalized copolymers having number average molecular weights generally greater than about 5000.
  • the precursor copolymers useful for radiation-reactive functionalization in the adhesive compositions, coatings and methods of the present invention include compositionally homogeneous copolymers having number average molecular weight (Mn) from about 5000 to about 500,000, preferably from about 50,000 to about 300,000, more preferably from about 05,000 to about 150,000. These products also exhibit a relatively narrow molecular weight distribution.
  • these functionalized copolymers thus exhibit M w /M n values of less than about 6, preferably less than about 4, more preferably less than about 2.5 and at the same time, depending upon the ultimate intended use thereof.
  • R and R' are, independently, selected from the group consisting of hydrogen, alkyl, preferably C 1 to C 5 alkyl, and primary and secondary alkyl halides, preferably primary and secondary C 1 to C 5 alkyl halides.
  • precursor copolymer products which operably comprise from about 10 to about 99.5 percent by weight, preferably between about 80 and 99 percent by weight, and most preferably from about 90 to about 98 percent by weight of the of the isoolefin or isobutylene and from about 0.5 to about 90 percent by weight, preferably from about 1 to about 20 percent by weight, more preferably from about 2 to about 10 percent by weight of the para-alkylstyrene, preferably para-methylstyrene.
  • thermoplastic materials comprising higher concentrations of para-alkylstyrene
  • the copolymers comprise from about 10 to about 99.5 percent by weight of the isoolefin, preferably isobutylene, and from about 0.5 to about 90 percent by weight, preferably from about 1 to about 90 percent by weight of the para-alkylstyrene, or preferably para-methylstyrene.
  • Isobutene and para-methylstyrene are readily cppolymerized under cationic conditions.
  • the polymerization can be carried out by means of a Lewis acid catalyst.
  • Suitable Lewis acid catalysts include those which show good polymerization activity with a minimum tendency to promote alkylation transfer and side reactions which can lead to branching and the production of crosslinks resulting in gel-containing polymers with inferior properties.
  • the preferred catalysts are Lewis acids based on metals from Group IIIa, IV and V of the periodic table of the elements, including boron, aluminum, gallium, indium, titanium, zirconium, tin, vanadium, arsenic, antimony, and bismuth.
  • the Group Ilia Lewis acids have the general formula R m MX n , wherein M is a Group IIIa metal, R is a monovalent hydrocarbon radical selected from the group consisting of C 1 to C 12 alkyl, aryl, alkylaryl, arylalkyl and cycloalkyl radicals; m is a number from 0 to 3; X is a halogen independently selected from the group consisting of fluorine, chlorine, bromine, and iodine; and the sum of m and n is equal to 3.
  • Nonlimiting examples include aluminum chloride, aluminum bromide, boron trifluoride, boron trichloride, ethyl aluminum dichloride (EtAlCl 2 ), diethyl aluminum chloride (Et 2 AlCl), ethyl aluminum sesquichloride (Et 1.5 AlCl 1.5 ), trimethyl aluminum, and triethyl aluminum.
  • the Group IV Lewis acids have the general formula MX 4 , wherein M is a Group IV metal and X is a ligand, preferably a halogen.
  • Nonlimiting examples include titanium tetrachloride, zirconium tetrachloride, or tin tetrachloride.
  • the Group V Lewis acids have the general formula MX Y , wherein M is a Group V metal, X is a ligand, preferably a halogen, and y is an integer from 3 to 5.
  • Nonlimiting examples include vanadium tetrachloride and antimony pentafluoride.
  • the preferred Lewis acid catalysts may be used singly or in combination with co-catalysts such as Bronsted acids, such as anhydrous HF or HCl, or alkyl halides, such as benzyl chloride or tertiary butyl chloride.
  • co-catalysts such as Bronsted acids, such as anhydrous HF or HCl, or alkyl halides, such as benzyl chloride or tertiary butyl chloride.
  • the most preferred catalysts are those which can be classified as the weaker alkylation catalysts, and these are thus the weaker Lewis acids from among the catalysts set forth above.
  • catalysts such as ethyl aluminum dichloride, and preferably mixtures of ethyl aluminum dichloride with diethyl aluminium chloride, are not the catalysts that are normally preferred for use in conventional alkylation reactions, since again in the present case there is a strong desire to minimize side reactions, such as the indanyl ring formation which would be more likely to occur with those catalysts normally used to promote conventional alkylation reactions.
  • the amount of such catalysts employed will depend on the desired molecular weight and the desired molecular weight distribution of the copolymer being produced, but will generally range from about 20 ppm to about 1 percent by weight, and preferably from about 0.001 to about 0.2 percent by weight, based upon the total amount of monomer to be polymerized therein.
  • Suitable diluents for the monomers, catalyst components and polymeric reaction products include the general group of aliphatic and aromatic hydrocarbons, used singly or in admixture, and C 1 to C 6 halogenated hydrocarbons used in admixture with hydrocarbon diluents in an amount up to about 100 percent by volume of the total diluent fed to the reaction zone.
  • the catalyst may not necessarily also be soluble therein.
  • the process can be carried out in the form of a slurry of polymer formed in the diluents employed, or as a homogeneous solution process.
  • a slurry process is, however, preferred, since lower viscosity mixtures are produced in the reactor, and slurry concentrations of up to about 40 percent by weight of polymer are possible.
  • slurry concentrations of up to about 40 percent by weight of polymer are possible.
  • the amount of diluent fed to the reaction zone should be sufficient to maintain the concentration of polymer in the effluent leaving the reaction zone below about 60 percent by weight, and preferably in the range from about 5 to about 35 percent by weight, depending upon the process being used and the molecular weight of polymer being produced.
  • Too high a concentration of polymer is generally undesirable for several reasons, including poor temperature control, rapid reactor fouling, and the production of gel. Polymer concentrations which are too high will raise the viscosity in the reactor and require excessive power input to insure adequate mixing and the maintenance of effective heat transfer. Such inadequate mixing and loss of heat transfer efficiency can thus result in localized high monomer concentrations and hot spots in the reactor which can in turn cause fouling of reactor surfaces.
  • typical examples of the diluents which may be used alone or in admixture include propane, butane, pentane, cyclopentane, hexane, toluene, heptane, isooctane, etc., and various halohydrocarbon solvents which are particularly advantageous herein, including methylene chloride, chloroform, carbon tetrachloride, methyl chloride, with methyl chloride being particularly preferred.
  • an important element in making the copolymer precursor of the present invention is the exclusion of impurities from the polymerization reactor, namely impurities which, if present, will result in complexing with the catalyst or copolymerization with the isoolefin or the para-alkylstyrene, which, in turn, will prevent one from obtaining the molecular weight properties necessary for making the pre-functionalized copolymer reactant and obtaining improved physical properties of the PSA or coating product of this invention.
  • polymers which do not have the substantially homogeneous compositional distributions and/or narrow molecular weight distributions of the present invention will be produced.
  • these impurities include catalyst poisoning materials, (i.e. moisture,) and other undesirable copolymerizable monomers, such as, for example, meta-alkylstyrenes and the like.
  • catalyst poisoning materials i.e. moisture
  • other undesirable copolymerizable monomers such as, for example, meta-alkylstyrenes and the like.
  • These impurities should be kept out of the system so that, in turn, the para-alkylstyrene is at least about 95.0 percent by weight pure, preferably at least about 97.5 percent by weight pure, and the isoolefin is at least about 99.5 percent by weight pure, and preferably at least about 99.8 percent by weight pure.
  • the diluents employed therein should be at least about 99.0 percent by weight pure, and preferably at least about 99.8 percent by weight pure.
  • the polymerization reactions are carried out by admixing the para-methylstyrene and isobutene in the presence of the catalyst (such as a Lewis acid catalyst) and diluent in a copolymerization reactor, with thorough mixing, and under copolymerization conditions, including temperatures less than about 0oC, in the case of lower molecular weight polymers, and providing a means of removing the heat of polymerization in order to maintain a desired reactor temperature.
  • the polymerization may be carried out under batch conditions of cationic polymerization, such as in an inert gas atmosphere and the substantial absence of moisture.
  • the polymerization is carried out continuously in a typical continuous polymerization process using a baffled tank-type reactor fitted with an efficient agitation means, such as a turbo-mixer or propeller, and draft-tube, external cooling jacket and internal cooling coils or other means of removing the heat of polymerization, inlet pipes for monomers, catalysts and diluents, temperature sensing means and an effluent overflow to a holding drum or quench tank.
  • the reactor must be purged of air and moisture and charged with dry, purified solvent or a mixture of solvents prior to introducing monomers and catalyst.
  • Reactors which are typically used in butyl rubber polymerizations are generally suitable for use in the polymerization reactions of the present invention copolymer intermediate.
  • These reactors are basically large heat exchangers in which the reactor contents are rapidly circulated through rows of heat exchange tubes which are surrounded by boiling ethylene so as to remove the heat of polymerization, and then through a central draft tube by means of an efficient marine-type impellor.
  • Catalyst and monomers are introduced continuously into the reactor and mixed by the pump, and reactor effluent then overflows into a steam-heated flash tank.
  • Heat of polymerization can also be removed by a pump-around loop in which the reactor contents are continuously circulated through an external heat exchanger in the loop.
  • the reactor When conducting a slurry polymerization process, the reactor is generally maintained at temperatures of from about -85oC to about -115oC, and preferably from about -89oC to about -96oC.
  • Solution polymerizations and cement suspension polymerizations can be run at much warmer temperatures, such as about -40oC, depending on the copolymer molecular weight desired and the particular catalyst system used. Therefore, an acceptable solution polymerization temperature range is from about -35oC to about -100oC, and preferably from about -40oC to about -80oC.
  • the overall residence time can vary, depending upon, e.g., catalyst activity and concentration, monomer concentration, reaction temperature, and desired molecular weight, and generally will be from about one minute to about five hours, and preferably from about 10 to about 60 minutes.
  • para-methylstyrene/isobutene copolymer ingredients of this invention also afford significant advantages when produced using a solution polymerization process. Since para-methylstyrene does not cause the severe molecular weight depression characteristic of dienes, and since the molecular weight versus polymerization temperature response of these new copolymers is much flatter than with diene functional butyl copolymers, high molecular weight copolymers can be made at much warmer temperatures (i.e., about -40oC versus less than about -90oC with the diene functional butyl copolymers). These warmer polymerization temperatures translate into a much lower viscosity at any given polymer concentration and molecular weight.
  • Solution polymerization has the further advantage, particularly with the para-methylstyrene/isobutene copolymer ingredients of this invention, in that the precursor copolymers are produced in a desirable solution state in which post-polymerization chemical modification can be conducted. It is also possible to halogenate and graft nucleophile containing moieties onto the precursor polymer in the bulk state (i.e., using an internal mixer, extruder, etc.), but most reactions can be more easily performed in a more controlled manner on polymer solutions, which afford better mixing, heat transfer, removal of unwanted by-products, etc.
  • cement suspension polymerization processes can also be carried out in the form of a so-called "cement suspension” polymerization process.
  • these are polymerization reactions carried out in a selected diluent such that the polymer is only slightly soluble in the diluent, and the diluent is sufficiently soluble in the polymer so that a second phase is formed which contains substantially all of the polymer, but wherein the continuous phase or diluent phase has a sufficiently low viscosity so that the second or polymer-rich phase can be dispersed therein.
  • cement suspension polymerizations they are carried out in such a diluent whose lower critical solution temperature for the polymer to be prepared is below the temperature at which the reaction is to be carried out.
  • the lower critical solution temperature is defined as the temperature above which the polymer is no longer soluble in a solvent.
  • a temperature will be reached above which the polymer is no longer soluble. If maintained at this temperature, separation of two phases will occur with generally the lower portion being a heavier polymer-rich phase and the upper portion being a lighter solvent-rich phase. This phenomenon can thus be utilized to separate polymers from solution in conventional solution polymerization processes as discussed above.
  • halogenation e.g., radical bromination
  • Functionality-introducing reactions such as halogenation are carried out on the precursor para-methylstyrene/isobutene copolymers produced by any of the above polymerization methods in a separate post-polymerization step, with direct halogenation, and most preferably radical halogenation, being the preferred reaction. It is generally desirable to treat the precursor polymerizaton copolymer product in an appropriate manner, prior to such halogenation, in order to quench the catalyst and/or remove catalyst residues, remove residual unconverted monomers, and put it into a convenient form for the halogenation reaction.
  • Residual unconverted monomers left in the precursor copolymer will react during halogenation to both consume halogen and produce generally undesirable by-products, and their presence thus renders it difficult to control and measure the amount of desired functionality introduced into the copolymer.
  • Unreacted isobutene is volatile enough to be easily removed in any of a variety of stripping operations, but para-methylstyrene, with its high boiling point of 170oC, is much more difficult to remove. It is therefore advantageous to polymerize at very high para-methylstyrene conversion levels so that its removal and/or recycle becomes unnecessary or, at least involves smaller amounts of material.
  • the halogenation reaction itself can be carried out in the bulk phase or on the precursor copolymer either in solution or in a finely dispersed slurry.
  • Bulk halogenation can be effected in an extruder, or other internal mixer, suitably configured to provide adequate mixing and for handling the halogen and corrosive byproducts of the reaction.
  • Bulk halogenation in an extruder has the advantages of permitting complete removal of residual unreacted para-methylstyrene by conventional finishing operations prior to halogenation, and of avoiding possible diluent halogenation as an undesired side reaction.
  • Solution halogenation is advantageous in that it permits good mixing and control of halogenation conditions to be achieved, easier removal of undesired halogenation by-products, and a wider range of initiators of halogenation to be employed. Its disadvantages include the need for removal of residual unreacted para- methylstyrene prior to halogenation, the presence of complicating side reactions involving solvent halogenation, and a solution step if a non-solution polymerization process is used to prepare the copolymer, as well as removal, clean-up and recycle of the solvent. Suitable solvents for such halogenation include the low boiling hydrocarbons (C 4 to C 7 ) and halogenated hydrocarbons.
  • the halogenation can also be conducted with the copolymer as a fine slurry or cement suspension in a suitable diluent which is a poor solvent for the copolymer.
  • a suitable diluent which is a poor solvent for the copolymer.
  • Halogenation of the precursor para-methylstyrene/isobutene copolymer intermediates is significantly different from halogenation of isobutene- isoprene (butyl) rubbers because the primary reactive site for halogenation is entirely different.
  • the para-methylstyrene/isobutene copolymers contain no in-chain (backbone) olefinic unsaturation contribution from the para-methylstyrene, and the primary reactive halogenation site is thus the enchained para-methylstyrene moiety, which is far less reactive than the olefinic site in butyl rubber.
  • chlorination reaction is run in a more polar (higher dielectric constant) diluent, such as methylene chloride, then chlorination does occur, but apparently by many different routes, so that a variety of different chlorinated products are produced thereby.
  • a more polar (higher dielectric constant) diluent such as methylene chloride
  • radical bromination of the enchained para-methyl styryl moiety in the copolymer ingredients of this invention can be made highly specific with almost exclusive substitution occurring on the para-methyl group, to yield the desired benzylic bromine functionality.
  • the high specificity of the bromination reaction can thus be maintained over a broad range of reaction conditions, provided, however, that factors which would promote the ionic reaction route are avoided (i.e., polar diluents, Friedel-Crafts catalysts, etc.).
  • solutions of the precursor para-methylstyrene/isobutene copolymer intermediates of this invention in hydrocarbon solvents such as pentane, hexane or heptane can be selectively brominated using light, heat or selected radical initiators (according to conditions, i.e., a particular radical initiator must be selected which has an appropriate half-life for the particular temperature conditions being utilized, with generally longer half-lives preferred at warmer halogenation temperatures) as promoters of radical halogenation, to yield almost exclusively the desired benzylic bromine functionality, via substitution on the para-methyl group, and without appreciable chain scission and/or cross-linking.
  • selected radical initiators accordinging to conditions, i.e., a particular radical initiator must be selected which has an appropriate half-life for the particular temperature conditions being utilized, with generally longer half-lives preferred at warmer halogenation temperatures
  • the bromination reaction proceeds by means of a rapid radical chain reaction with the chain carrier being, alternatively, a bromine atom and a benzylic radical resulting from hydrogen atom abstraction from a para-methyl group on the enchained para-methylstyryl moiety.
  • the proposed mechanism thus involves the following steps: (1) initiation
  • R-R 2R ⁇ (Rbeing an lnit.tt.no radical)
  • the reaction terminates when one of the radicals reacts with some radical trap in the system, or the radicals destroy themselves by recombination or disproportionation.
  • This reaction can be initiated as shown in step (1) above by formation of bromine radicals, either photochemically or thermally (with or without the use of photosensitizers), or the radical initiator used can be one which preferentially reacts with a bromine molecule rather than one which reacts indiscriminately with bromine radicals, or with the solvent or polymer (i.e., via hydrogen abstraction).
  • the sensitizers referred to are those photochemical sensitizers which will themselves absorb lower energy photons and dissociate, thus causing, in turn, dissociation of the bromine, including materials such as iodine.
  • an initiator which has a half life of from about 0.5 to about 2500 minutes under the desired reaction conditions, more preferably from about 10 to about 300 minutes.
  • the amount of initiator employed will usually vary from about 0.02 to about 0.3 percent by weight.
  • the preferred initiators are bis azo compounds, such as azobisisobutyronitrile, azobis(2,4-dimethylvaleryl)-nitrile, azobis(2-methylbutyro)nitrile, and the like.
  • Other radical initiators can also be used, but it is preferred to use a radical initiator which is relatively poor at hydrogen abstraction, so that it reacts preferentially with the bromine molecules to form bromine radicals rather than with the precursor copolymer or solvent to form alkyl radicals. In those cases, there would then tend to be resultant copolymer molecular weight loss, and promotion of undesirable side reactions, such as crosslinking.
  • the radical bromination reaction of this invention is highly selective, and almost exclusively produces the desired benzylic bromine functionality. Indeed, the only major side reaction which appears to occur is disubstitution at the para-methyl group, to yield the dibromo derivative, but even this does not occur until more than about 60 percent of the enchained para- methylstyryl moieties have been monosubstituted. Hence, any desired amount of benzylic bromine functionality in the monobromo form can be introduced into the copolymers of this invention, up to about 60 mole percent of the para-methylstyrene content. Furthermore, since the para- methylstyrene content can be varied over a wide range as described herein, it is possible to therefore introduce a significant functionality range.
  • the halogenated copolymer ingredients of this invention are thus highly useful in subsequent reactions, for example, crosslinking reactions. Once the bromide leaving group is incorporated, the copolymer can be functionalized with a radiation-sensitive nucleophile compound.
  • HBr Since one mole of HBr is produced for each mole of bromine reacted with or substituted on the enchained para-methylstyryl moiety, it is also desirable to neutralize or otherwise remove this HBr during the reaction, or at least during polymer recovery in order to prevent it from becoming involved in or catalyzing undesirable side reactions.
  • neutralization and removal can be accomplished with a post-reaction caustic wash, generally using a molar excess of caustic on the HBr.
  • neutralization can be accomplished by having a particulate base (which is relatively non- reactive with bromine) such as calcium carbonate powder present in dispersed form during the bromination reaction to absorb the HBr as it is produced. Removal of the HBr can also be accomplished by stripping with an inert gas (e.g., N 2 ) preferably at elevated temperatures.
  • an inert gas e.g., N 2
  • base terpolymers of this invention can be recovered and finished using conventional means with appropriate stabilizers being added to yield highly desirable and versatile functionalized saturated copolymer which are useful in the nucleophilic substitution reactions which follow to incorporate UV- or other radiation-reactive functionality.
  • the benzylic bromine (halogen) functionality is uniquely suited, as the base from which the versatile functionalized saturated copolymers employed in the adhesive or coating compositions of this invention can be prepared because it can be made to undergo selective nucleophilic substitution reactions with a great range of nucleophiles, so that almost any desired type and amount of functionality can be introduced without undesirable side reactions and under conditions which are mild enough to avoid degradation and/or crosslinking of the saturated copolymer backbone containing the pendant benzylic halogen functionality.
  • the mixed functionality can advantageously provide unique combinations of properties, such as grafting with another functional polymer via one of the functionalities and then cross-linking or adhering to some surface via another of the functionalities.
  • benzylic halogen functionality of the radically halogenated isobutylene/para-methylstyrene copolymers which makes them an "ideal" base copolymer from which to prepare the various radiation-reactive functionalized saturated copolymer ingredients is the wide range of nucleophilic substitution reactions this benzylic halogen functionality will undergo and the relatively mild conditions under which these nucleophilic substitution reactions will proceed.
  • a benzylic halogen functionality constitutes a very active electrophile which will react under suitable conditions with any nucleophile capable of donating electrons to it. Suitable nucleophiles include those containing oxygen, sulfur, nitrogen, phosphorus, carbon, silicon, and various metals including especially magnesium, lithium, sodium, and potassium.
  • Suitable UV- reactive nucleophiles include, for example, UV-reactive carboxylate esters, dithiocarbamate esters, and the like. Equally important to this versatility in types of nucleophiles which will react with the benzylic halogen functionality is the relatively mild conditions under which these nucleophilic substitution reactions proceed so that substitution reactions can be completed to introduce the desired new functionality without cleavage or crosslinking reactions involving the saturated hydrocarbon backbone of the isobutylene/para-methylstyrene copolymer. Another of the attributes of the benzylic halogen functionality is the selectivity with which the desired substitution reactions can be made to proceed without undesirable side reactions. The benzylic halogen functionality will undergo clean substitution reactions without complicating elimination reactions.
  • Tiny almost insignificant (in other reactions) amounts of side reactions which produce gel may interfere with usefulness. Furthermore, purification of the substituted polymer to remove unwanted side products is usually very difficult or impossible. This is why the selective single route to high yield nucleophilic substitution reactions achievable with benzylic halogen functionality under controlled conditions is important.
  • isobutylene/para-methylstyrene/para-bromomethylstyrene terpolymers as a "base" polymer for modification, and by conducting nucleophilic substitution reactions under appropriate and controlled conditions, soluble, backbone-saturated copolymers containing useful pendant functionality have been prepared. Examples include:
  • Esters many containing other function groups such as acetate, stearate linoleate, eleostearate, cinnamate, etc.; (2) Hydroxyl (attached directly in place of the benzylic bromine or attached via another linkage);
  • nucleophile and reaction medium so as to achieve the required intimate contact between the benzylic halogen attached to the base terpolymer and the nucleophile. It should be recognized that in some instances this can be accomplished by using a different solvent or reaction medium for the polymer and for the nucleophile and then employing an appropriate phase transfer catalyst to promote the reaction.
  • nucleophilic reagent and promoters appropriately so that the desired substitution reaction occurs quickly under mild conditions and potential undesired side reactions are avoided.
  • a carboxylic nucleophile in an esterification reaction to replace the benzylic bromines on an isobutylene/para-methylstyrene/ para-bromo- methylstyrene "base" terpolymer
  • reaction conditions to minimize sequential reactions by recognizing that the nucleophilic substitution reaction being conducted can itself form attached pendant nucleophilic reagents on the base copolymer backbone and that these already attached nucleophilic reagents can nucleophilically "attack" other unreacted benzylic bromines on the base terpolymer in a sequential manner to consume the desired, already attached new functionality, and at the same time produce undesirable crosslinking and gelation.
  • reaction conditions must be chosen such that the unreacted nucleophilic reagent being used in the nucleophilic substitution reaction is either a much stronger, more reactive nucleophile, or is present in great excess over any attached nucleophilic functionality produced in the substitution reaction.
  • polymers of isoolefin and para-alkylstyrene-silane derivatized polymers represent another broadly useful family of materials which can be easily prepared by nucleophilic displacement through the use of suitable nucleophilic silane reagents like (N,N-dimethyl-3-aminopropyl) silanes, as depicted below:
  • R 1 , R 2 and R 3 are each independently selected from the group consisting of hydrogen, chloro and alkoxy having from 1 to about 5 carbon atoms such as methoxy, ethoxy, etc.
  • the reactivity of these derivatives can be varied based upon the number and type of silane species present.
  • the polymers of isoolefin and para-alkylstyrene containing Si-Cl bonds are the most reactive toward a variety of nucleophiles, including a nucleophile as weak as water. Thus , these materials are vulcanizable by exposure to the atmosphere and are therefore very useful as room temperature vulcanizable compositions (RTVs) .
  • these polymers containing Si-O (alkyl) bonds are also reactive with a variety of nucleophiles (though not as reactive as Si-Cl) which also include water. Again this reactivity can be exploited in RTV applications , especially where the emission of neutral species during curing is preferred.
  • Appropriate applications for this silane chemistry include sealants and adhesives where the silane functional group allows for crosslinking and improves adhesion to substrates such as glass.
  • the Si-H functionality will react with olefins in the presence of certain free radical or precious metal catalysts. This reaction opens the opportunity for addition cure (RTV) or low temperature vulcanization. Mixtures of these polymers with another olefin containing polymer like polybutadiene or vinyl functional silicones will rapidly yield a intermolecular crosslinked system of the polymers of isoolefin and para-alkylstyrene and the other polymer.
  • the polymers of isoolefin and para- alkylstyrene-vinyl silicone system will provide a useful thermally stable crosslink system which exhibits improved permeability properties over existing silicone systems.
  • Si-H polymers of isoolefin and para-alkylstyrene derivatives are known to be active mild selective reducing agents for nitroaromatic ⁇ , acid chlorides, aldehydes and ketones. Binding these reagents to polymers offers the advantage of ease of separation; the polymer is easy to remove from the low molecular weight reduced species and no hydrolysis of the remaining reagent is necessary prior to isolation. Another advantage is that these reductions can be run in the presence of air and moisture in a wide range of solvent systems including hexane, methylene chloride and dioxane.
  • novel versatile, pendant functionalized, backbone saturated, soluble copolymers of this invention which are derived via selective nucleophilic substitution reactions on a "base" terpolymer comprising isobutylene/para-methylstyrene and para- bromomethylstyrene are widely useful as will be further disclosed in the examples dealing with specific pendant functionalities. They encompass a broad range in properties ranging from low T 9 elastomers high in isobutylene to high T 8 plastics high in para- methylstyrene with tough high impact compositions at intermediate isobutylene contents. The presence of appropriate pendant functionality renders this entire range of products "paintable" for use in external automotive or appliance applications, etc.
  • compositions to react with or be coreacted with other functional polymers, or fillers, or fibers to form composite structures (i.e. laminates, dispersions, etc.) with desirable combinations of properties.
  • novel pendant radiation-reactive functionalized saturated copolymer ingredients described and exemplified herein can be conveniently and practically produced by first preparing a base terpolymer comprising a saturated hydrocarbon backbone with one or more pendant attached electrophilic moieties, and then attaching the desired new radiation-reactive functionality via a selective nucleophilic substitution reaction with the pendant attached electrophilic moieties. It has been found to be desirable, and is important in obtaining the pendant functionalized copolymer ingredient of this invention, that the pendant attached electrophilic moieties which are replaced by other functionalities via selective nucleophilic substitution reactions be benzylic halogen moieties.
  • pendant attached electrophilic benzylic halogen moieties can be readily inserted into random isobutylene/para-methylstyrene copolymers by radical halogenation as mentioned previously to yield the base terpolymer containing isobutylene/para-methylstyrene/and brominated para-methylstyrene securing random units.
  • This base terpolymer containing electrophilic benzylic halogen moieties is the "parent" polymer from which the novel, pendant functionalized, saturated copolymers of this invention are prepared via selective nucleophilic substitution reactions.
  • novel pendant functionalized polymers of this invention are comprised of the following "mer” units: a) enchained isobutylene unit enchained p-alkylstyrene unit
  • R and R' are independantly selected from the group consisting of hydrogen, alkyl, and primary or secondary alkyl halide
  • X is a halogen atom (preferably bromine or chlorine, and most preferably bromine)
  • Y represents a new radiation-reactive group attached to the represents a new radiation-reactive group attached to the polymer via nucleophilic substitution of one of the benzylic halogens so that an enchained c "mer” unit has become a d "mer” unit
  • Z represents a new non- radiation-reactive group attached to the polymer via nucleophilic substitution of one of the benzylic halogens so that an enchained c "mer” unit has become an e "mer” unit.
  • Y and/or Z are the residues which become attached to the polymer enchained c "mer" unit in place of halogen when a nucleophilic reagent capable of donating electrons to benzyl halides is reacted with the base terpolymer in accordance with this invention.
  • the four (or more if several different Y and/or Z functionalities are present) "mer" units are attached to one another in random fashion to form the novel, pendant radiation-reactive functionalized, backbone saturated polymer ingredients in the compositions of this invention.
  • Total polymer number average molecular weight can range from ⁇ 500 to ⁇ 100,000.
  • the amounts of the various "mer” can range as follows:
  • Y and/or Z are the residues which become attached to the polymer unit in place of halogen when a nucleophilic reagent capable of donating electrons to benzyl halides is reacted with the base terpolymer in accordance with this invention, wherein a) is from about 10 to about 99.5 percent by weight, more preferably from about 80 to about 99 percent by weight, and most preferably from about 90 to about 98 percent by weight, b) is from about 0.5 to about 90.0 percent by weight, more preferably from about 1 to about 20 percent by weight, and most preferably from about 2 to about 10 percent by weight, d) is from about 0.5 to about 55.0 percent by weight, more preferably from about 0.5 to about 20 percent by weight and most preferably from about 0.5 to about 15 percent by weight, c) is from 0 to about 55.0 percent by weight, more preferably from 0 to about 20 percent by weight
  • the nucleophilic reagents which are capable of donating electrons to benzyl halides and to displace a halide ion via a substitution nucleophilic displacement reaction and attach the radiation-reactive functional group Y, and optionally the non-radiation-reactive functional group Z, in the benzylic position from which the halogen was displaced may be Y or YM, or Z or ZM, wherein: M is hydrogen, a metal ion, or an onium ion and Y and/or Z are either a simple nucleophile containing oxygen, sulfur, silicon, carbon, nitrogen, phosphorus, or various metals; or Y and/or Z are a small molecule of ⁇ 1000 molecular weight which may contain other functionality in addition to the simple nucleophile which become attached at the benzylic position in the nucleophilic displacement reaction. Examples of simple nucleophiles containing oxygen which results in the attachment of -O- to the benzylic
  • Examples of simple nucleophiles containing sulfur which result in attachment of -S- to the benzylic position from which the halide ion was displaced include (but are not limited to):
  • organo lithium (or other alkali or alkaline earth metals) compounds as in organo lithium (or other alkali or alkaline earth metals) compounds
  • HC-(R)-(CO 2 R) 2 as in malonates and di- or trisubstituted methane derivatives in general in which the substituents activate methane carbon for carbon-alkylation reactions under basic conditions.
  • Examples of simple nucleophiles containing nitrogen which result in the attachment of -N- to the benzylic position from which the halide ion was displaced include (but are not limited to) : as in amides
  • Z is some functional group as in iminodiethanol, iminodiacetonitile, di- acetonitrile iminodiacetic acid, etc.
  • ⁇ 1000 molecular weight containing other functionality in addition to the simple nucleophile which becomes attached at the benzylic position from which the halide ion was displaced in the nucleophilic displaced reaction include (but are not limited to) : triethanol amine, iminodiacetic acid, iminodiacetonitrile, iminodiethanol, vinyl pyridines, cinnamate, eleostearate, linoleate, aerylate, benzoyl benzoate, benzoyl phenolate, dihydroxybenzophenone, crown ethers derivatives, cryptand derivatives, cellulose derivatives, sugar derivatives, low molecular weight polyethylene oxide or polypropylene oxide chains with terminal nucleophilic groups, etc.
  • lube oil dispersants enables functionalities that are not readily achieved by the nucleophilic displacement reaction (such as olefins or conjugated unsaturation) to be attached; and enables very complex and special functionalities such as chiral compounds or crown compounds of cryptands to be attached to produce novel pendant functionalized copolymers of this invention with unique properties for highly specialized applications such as catalysts and so forth.
  • attachment of Y and/or Z groups containing other functionalities requires even greater care during the nucleophilic displacement reaction by means of which the Y and/or Z groups are attached to insure that the new functionalities are preserved and are not consumed by sequential reactions to produce unintended crosslinking or gelation. In some instances, it may be desirable to block the functionalities that need to be preserved until the nucleophilic substitution reaction is completed.
  • nucleophilic substitution reactions of this type also involve some degree of side reactions which can be extremely detrimental in making the pendant functionalized soluble copolymers of this invention, since even minor amounts of side reactions in high polymers can lead to unintended gelation which can greatly diminish utility.
  • One advantage of using the unique base polymers of this invention for the nucleophilic substitutions reactions is that the undesired side reactions can be largely eliminated. It is known that nucleophilic substitution reactions can proceed by several different mechanisms, and with most electrophiles these different mechanisms can lead to different products or to different amounts of side reactions.
  • benzylic halogen especially benzylic bromine
  • benzylic bromine as the enchained electrophile site for nucleophilic substitution as in this invention also makes it possible to select reagents and conditions so that other side reactions, such as those proceeding by another mechanism or the sequential reactions can be largely eliminated so that the soluble pendant functionalized copolymers of this invention can be prepared by selective S M 2 nucleophilic substitution reactions. Careful observance of the six "key" requirements already outlined is necessary in order to prepare the radiation-reactive pendant functionalized backbone saturated, soluble polymers of this invention.
  • the nucleophilic substitution reactions can be run in solution using a solvent system in which both the base polymer and nucleophilic reagent are soluble; can be run in a two-phase liquid system with the base polymer dissolved in one phase and the nucleophilic reagent in the other; can be run in a two-phase solid/liquid system (i.e. with the base polymer dispersed in a liquid phase containing the nucleophilic reagent) ; or can be run in bulk with reactants dissolved or dispersed in the base polymer.
  • the common solution situation is most controllable and generally the preferred case, but the bulk reaction may be economically advantageous in some cases where suitable reagents and reaction conditions can be found.
  • the intermediate two-phase systems may be advantageous under some circumstances and may be necessary in instances where the solubility parameters of the base polymer (containing the electrophile) and the nucleophilic reagent are so different that no common solvents exist.
  • a most preferred way of preparing the pendant functionalized polymers of this invention is to radically halogenate a random isobutylene/para-methylstyrene copolymer, as taught previously, to introduce the benzylic halogen electrophile, and then conduct the nucleophilic substitution reaction to introduce the desired new functionality in the same medium in a sequential reaction (halogenate and then nucleophilically displace the halogen) without ever recovering the base halogenated polymer separately.
  • the nucleophilic substitution reactions can be run at temperatures varying from about 0oC to about 200oC as limited by thermal stability of the nucleophilic reagent, the base polymer and the functionalized product polymer.
  • reaction times are normally (but not necessarily) chosen to allow the nucleophilic displacement reaction to go to completion (i.e. exhaustion of either the electrophile or the nucleophilic reagent) and may range between several seconds and a few days. Normally, reaction times between a few minutes and several hours are preferred and reaction temperature and other conditions are set to make a convenient reaction time possible.
  • a wide range of solvents and/or solvent blends may be used as the medium in which the nucleophilic displacement reation is run and it is this factor which determines whether a solution, dispersion, or bulk reaction is conducted.
  • a number of factors are important in selection of the the solvents. They need to be inert under the reaction conditions, easily removed from the product, easily recycled for reuse in the process, of low toxicity under use conditions with minimum environmental health concerns, and economical to use.
  • the solvents need to provide a reaction environment which is favorable for the reaction being run, that is, they must bring the reactants into the required intimate solution contact and should provide solvation stabilization for intermediate states along the desired reaction route.
  • the chosen solvent system be one that is suitable for both the radical halogenation reaction to introduce the benzylic halogen electrophile into the random isobutylene/para-methylstyrene copolymer, as well as for the nucleophilic substitution reaction to introduce the new pendant functionality, so that a sequential reaction route is feasible without having to recover the halogenated base polymer separately.
  • Solvents which are particularly suited for this sequential reaction route vary somewhat depending upon composition of the base polymer, but with the elastomeric base polymers high in isobutylene are the low boiling saturated hydrocarbons (C 4 -C 7 ) or halogenated hydrocarbons (C 1 -C 7 ). Often it is desirable to add a more polar cosolvent, such as a low boiling alcohol (C 1 -C 4 ) during the (second) nucleophilic displacement reaction in order to dissolve and carry-in the nucleophilic reagent, as well as provide solvation stabilization for the nucleophilic displacement reaction.
  • a more polar cosolvent such as a low boiling alcohol (C 1 -C 4 ) during the (second) nucleophilic displacement reaction in order to dissolve and carry-in the nucleophilic reagent, as well as provide solvation stabilization for the nucleophilic displacement reaction.
  • Aromatic solvents such as benzene, toluene, and chlorobenzene are generally good solvents for the base polymer over the entire composition range and provide a reaction medium favorable for many nucleophilic displacement reactions, but often present other problems (i.e. the toxicity of benzene or the high reactivity of toluene during radical halogenation which makes it unsuitable as the reaction medium during this first stage of the sequential reaction route).
  • Preferred solvent composition changes as composition of the base polymer is changed and depends upon whether it is desired to run the reactions in solution or dispersion. In general, solvents of higher solubility parameter containing some aromaticity or halogen are required for solution reactions with the tougher, higher T 8 base polymers of this invention which contain higher para-methylstyrene contents.
  • tetrahydrofuran can be employed or good solvating agents such as dimethyl formamide or dimethyl sulfide can be added.
  • the latter solvents are also good solvents for many of the nucleophilic reagents and may be employed along with alcohols or ketones to dissolve the nucleophilic reagent for addition to the base polymer solution.
  • nucleophilic reagent is not soluble in co-solvents miscible with the base polymer solvent, or where the solubility of the nucleophilic reagent in mixed solvency (which will retain the base polymer in solution) is too low, then a two- phase reaction may be run with the base polymer dissolved in one phase and the nucleophilic reagent in the other.
  • good mixing is essential to provide lots of interfacial contact between the reactants, and a phase transfer catalyst is generally desirable to aid in transporting the nucleophilic reagent to the benzylic halogen electrophile site on the base polymer.
  • the most convenient reaction condition is to run a bulk reaction with the nucleophilic reagent dissolved or dispersed in the base polymer.
  • Working with high solids eliminates the costs of solvent handling and recycle.
  • the bulk reaction requires use of an expensive inefficient reactor such as an extruder which is capable of providing mixing in highly viscous systems and restricts the reaction medium so that only selected nucleophilic displacement reactions are possible, and even those are more prone to involve side reactions because of the more restrictive conditions and poorer mixing which prevails during reaction.
  • reaction routes and activation energy can be controlled by specific solvation, or catalysts, undesired reactions can be prevented by blocking, etc.
  • Polyken Probe Tack (ASTM-D2979) measures the stress required to separate an end of a steel rod from the adhesive film. Test conditions are 1 cm/sec probe speed, 100 g/cm 2 probe pressure and 1 sec dwell time.
  • the 180o peel adhesion test (PSTC- 1) measures the force necessary to strip or delaminate an adhesive tape as prepared above in the Polyken Probe Test. A 1 inch wide tape is adhered to a clean substrate bar and the bar is mounted in an Instron tester. The free end is pulled away at a 180o angle at a rate of 12 in/min.
  • PSTC-5M The 90o quick stick adhesion test (PSTC-5M) measures the property of a pressure sensitive tape which results in instant adhesion to a surface using no external pressure to secure more thorough contact. It is measured as the force resisting pealing of a tape at a 90o angle from a standard surface upon which it has been applied under no other pressure but the weight of the tape itself.
  • the loop tack (PSTC-5) is measured by forming a loop from a 1" ⁇ 8" modified strip of tape, adhesive face out, inserted into the clamp of an Instron tester and moving the loop at a rate of 12 in./min onto a stainless steel panel then removing the strip at the rate of 2 in./min after 5 square inches of contact is made. The highest force required to remove the loop is reported.
  • Holding power (PSTC-7) (HP) is defined as a time required for a 1" ⁇ 1" area or a 1/2" ⁇ 1" area of label adhered to steel to fail under a load of 1 kg applied in shear at a 2o antipeel. Unless otherwise noted, the HP reported is based on the 1" ⁇ 1" label area method.
  • SAFT Shear adhesion fail temperature
  • Gel refers to the insoluble residue of rubber in the adhesive and is determined by exhaustive solvent extraction of soluble polymer in refluxing toluene for about 72 hours, then drying and weighing the remaining residue.
  • the coatings were prepared by dissolving the polymers or formulations in toluene and knife coating onto MYLAR or release paper. The coatings were then dried and irradiated. The coating thicknesses were typically 1.5 mil. UV irradiation was conducted on an American Ultraviolet Mini-Conveyorized Curing System. UV dosages were determined using the UVA cure radiometer manufactured by EIT. EB crosslinking was performed on an Energy Sciences CB-150 Electrocurtain Electron Beam Accelerator. Example 1
  • a 500 ml reaction flask fitted with a thermometer, stirrer, and dropping funnel was set up in a glove box having an oxygen- and moisture-free nitrogen atmosphere, and the flask was cooled to -98 oC by immersion in a controlled temperature liquid nitrogen cooled heat transfer bath.
  • the reactor was charged with 386.6 g purified dry methyl chloride (having a purity of 99.8%), 47.4 g purified, dried and distilled polymerization grade isobutylene (having a purity of 99.9%), and 2.6 g purified, dried and vacuum-distilled para-methylstyrene (2.5 mole % of total monomers).
  • the polymer was recovered by allowing the methyl chloride to flash off and kneading and washing the polymer in methanol; 0.2 weight percent butylated hydroxytoluene (BHT) was added as an antioxidant and the polymer was dried in a vacuum oven at 80 oC. Fifty grams of dried white, opaque, tough, rubbery polymer were recovered. Conversion was 100% with a quantitative recovery of the polymer. Catalyst efficiency was about 1550 grams of polymer/gram of EADC.
  • the recovered polymer had a viscosity average molecular weight (My) of 458,000, and contained 5.2 weight percent (2.5 mole percent) para- methylstyrene.
  • the GPC was performed using a Waters 150-C ALC/GPC (Millipore Corporation) with a Waters Lambda-Max Model 481 LC UV Spectrophotometer on line. Data were collected and analyzed using customized software developed with Computer Inquiry Systems, a division of Beckman Inc. Tetrahydrofuran was used as the mobile phase at various flow rates, but generally 1.0 ml/min. The instruments operated at 30oC at a wavelength of about 254 nm for the UV. The polyisobutene backbone has negligible absorbance compared to the aromatic ring at this wavelength. Columns used were ⁇ Styragel (Waters) or Shadex (Showa Denko).
  • the high molecular weight random uniform copolymer of para-methylstyrene and isobutene prepared as above was dissolved in dried normal hexane in a two-liter baffled and jacketed resin flask set up for bromination with a four-neck resin flask top.
  • An air-driven turbine mixer was used to provide efficient mixing, and a thermometer and thermocouple were used to measure and control the temperature, which was adjusted as noted hereinbelow by circulating a controlled temperature heat transfer fluid through the jacket.
  • One of the necks was used for mounting a dropping funnel containing the bromine solution, which was added dropwise into the reactor.
  • the funnel and reactor were foil-wrapped to exclude light.
  • a nitrogen bubbler tube with a sintered glass frit at the end was mounted in one of the necks, with the frit immersed in the reactor solution to provide nitrogen sparging at a rate which was set and controlled by a rotometer.
  • the fourth neck was connected by plastic tubing to a knock-out trap and caustic scrubber in order to maintain several inches of water positive pressure during reaction, and to absorb and neutralize any HBr and bromine vapors given off during the reaction.
  • the bromine solution was prepared by adding a weighed amount of bromine to pure mole-sieve dried n- hexane (essentially olefin-free) in the dropping funnel, and mixing to form less than a 30% solution.
  • the foil- wrapped (to protect from the light) bromine dropping funnel was then mounted on the stirred, temperature- controlled, nitrogen-purged reactor, and a 500 watt tungsten light bulb was mounted immediately next to the reactor.
  • the reactor was heated to 40oC and the bromine solution added dropwise.
  • the bromine charge was 5 percent by weight of the copolymer, and the reaction occurred rapidly as the bromine was added, as evidenced by rapid HBr evolution and rapid fading of the color of the solution.
  • a tough ionically crosslinked quaternary ammonium salt derivative of a random isobutylene/ para-methylstyrene/para-bromomethylstyrene base terpolymer was prepared.
  • the base terpolymer was prepared in accordance with the procedure of Example 1.
  • a random isobutylene/para-methylstyrene copolymer containing 2.4 mole percent para-methylstyrene and having a Mooney viscosity of 30 was polymerized in a commercial 1800 gallon butyl polymerization reactor and then radically brominated using VAZO 52 initiation in hexane solution in a 100 gallon glass-lined Pfaudler Br reactor to give a base terpolymer with a Mooney viscosity of 29 containing 2.6 weight percent bromine.
  • the base terpolymer composition was 1.4 mole percent para- bromomethylstyrene (including 0.1 mole percent dibrominated para-methylstyrene) 0.9 mole percent unbrominated para-methylstyrene and 97.7 mole percent isobutylene (there was a small amount of dibromination and slight molecular weight loss due to the relatively high bromination level of 61 percent of para-methylstyrene "mer" units.
  • the solution was then heated with stirring to the reflux temperature of about 85-86%C under slight nitrogen purge.
  • the solution was stirred and refluxed for 6 hours and then allowed to cool under nitrogen.
  • a trial on a sample aliquot showed that the solution emulsified when shaken with water or water/alcohol (70/30) mixtures so it could not be washed.
  • the emulsions had a pH of 8. The emulsions remained stable when acidified and even when the pH was raised to 10-11 with NaOH solution, the solution would still not separate well.
  • the functionalized polymer was recovered by precipitation and kneading in isopropanol and further separated from unreacted triethyl amine by redissolving in a toluene/isopropanol blend and precipitation in isopropanol.
  • the purified functionalized polymer was vacuum oven dried at 701 ⁇ 2C after 0.2 weight percent BHT had been mixed in as an antioxidant.
  • the dried recovered polymer was a spongy, slightly off-white, extremely tough, ionically crosslinked elastomer.
  • the pendant cationic quaternary ammonium salt groups which had become attached to the "base" terpolymer by nucleophilic displacement of the benzylic bromines self-associated to give a tough ionically crosslinked elastomer. It was insoluble in hydrocarbons or alcohols but readily dissolved in a 90/10 toluene/isopropanol mixed solvent which disrupted the ionic crosslinks by solvation.
  • the nucleophilic displacement reaction is shown below:
  • the proton NMR spectrograph showed the disappearance of the resonances at 4.47 ppm due to the benzylic hydrogens adjacent to the bromine and the appearance of two new resonances: one at 4.7 ppm due to the benzylic hydrogens adjacent to the quaternary nitrogen and another at 3.5 ppm due to the methylene hydrogens adjacent to the quaternary nitrogen.
  • the resonances at 2.3 ppm due to the paramethyl hydrogens of the enchained para- methylstyrene "mer" units remained unchanged by the nucleophilic substitution reaction:
  • a portion of the dried pendant functionalized polymer of this example was dissolved in a 90/10 hexane/isopropanol solvent blend to give a 15 weight percent solution. This solution was cast on a glass plate and the solvent was allowed to evaporate to deposit a tough rubbery film. Drying was completed in a vacuum oven at 70oC. An extremely tough ionically crosslinked film with excellent adhesion to the glass was deposited in this way. The film could be dissolved off again with the mixed hydrocarbon/alcohol solvent blend. In a similar manner, a film of tough ionically crosslinked elastomer was deposited on several porous substrates (i.e.
  • a pendant functionalized primarily isobutylene-based copolymer containing a cationic quaternary ammonium salt group was prepared and converted to an emulsion-free stable latex.
  • An isobutylene-based polymer with an M v of 45 , 000 and containing 2 mole percent para-chloromethylstyrene "mer" units was dissolved in a 70/30 toluene/isopropanol solvent blend to form a 35 weight percent solution by overnight shaking in a 2 gallon container.
  • Example 2A Recovery of a sample of the pendant functionalized copolymer for analysis is outlined in Example 2A. Recovery steps include precipitation and kneading in isopropanol , resolution in toluene/isopropanol and reprecipitation in isopropanol before vacuum-oven drying at 70 o C with 0.2 weight percent BHT mixed in as an antioxidant.
  • the purified and dried pendant functionalized copolymer was an extremely tough white crumb ionically crosslinked as shown by its insolubility in toluene but ready solubility in a 90/10 toluene/isopropanol solvent blend. Analysis showed that complete conversion of benzylic chlorines to quaternary ammonium salt groups had occurred.
  • the recovered copolymer contained 0.48 weight percent nitrogen and NMR analysis showed the presence of 2 mole percent benzyl triethyl ammonium chloride salt groups.
  • the balance of the cooled reaction effluent solution was simply mixed as is with distilled water at a 40/60 water/solution ratio by volume to give a stable oil-in-water emulsion which was refined first with a dispersator and then in a colloid mill to give a very stable fine particle size raw latex.
  • the raw latex was stripped by heating with stirring under nitrogen to remove the solvents and part of the water to give a stable finished latex containing 50 percent solids.
  • No emulsifiers were required in making the latex and the preparation and stripping were accomplished easily without the foaming problems normally experienced in preparing, stripping and concentrating latices containing added soaps as emulsifiers.
  • a pendant functionalized primarily isobutylene-based copolymer containing cationic quaternary phosphonium salt groups was prepared and converted to a stable, emulsifier-free latex.
  • An isobutylene-based polymer with an My of 17,000 and containing 1.9 mole percent para-chloromethylstyrene "mer" units was dissolved in a dried 75/25 heptane/isopropyl alcohol solvent blend under nitrogen to form a 40 weight percent polymer solution in a 5 1 "ell” resin flask.
  • the reactor was connected through a dry ice-cooled cold finger (setup to reflux condensables back into the flask) to a scrubber for vented gasses and bubbler to maintain several inches of water positive pressure on the reactor.
  • a slow dry nitrogen flow was maintained through the system to maintain the reactants under a dry, inert atmosphere.
  • twice the stoichiometric amount of triethyl phosphine (on benzylic chlorine) as a 67 weight percent solution in isopropanol was added dropwise from a sealed dropping funnel.
  • the mixture was heated with stirring to the reflux temperature of 77oC and refluxed for 2 hours under nitrogen and constent stirring before being cooled.
  • a sample of the pendant functionalized polymer was recovered from the resulting clear effluent solution for analysis.
  • the recovery process comprised the steps of precipitation and kneading in isopropanol, resolution in hexane/isopropanol solution, and reprecipitation from isopropanol followed by vacuum-oven drying at 70oC with 0.2 percent BHT mixed in as an antioxidant.
  • the recovered polymer was a tough elastomeric ionically crosslinked polymer very unlike the soft, sticky, semi-fluid starting base terpolymer. Analysis showed it contained 0.95 mole percent phosphorus indicating about 50 percent conversion of benzylic chlorines to quaternary phosphonium salt groups had occurred.
  • Example 2B The remaining cooled solution from the nucleophilic substitution reaction was simply mixed as is with distilled water a 40/60 water/solution ratio by volume to give a stable oil-in-water emulsion which was refined and then stripped and concentrated as in Example 2B to give a stable, emulsifier-free, fine particle size, cationic, latex at 50% solids by weight.
  • the latex preparation and stripping was accomplished easily without foaming problems, and castings from the latex dried to hydrophobic, clear, tough, ionically crosslinked, elastomeric films which would be useful in a broad spectrum of applications as already outlined.
  • the pendant functionalized polymer of this latex contained mixed functionalities, including benzylic chlorines and quaternary phosphonium chloride salt groups because the nucleophilic substitution reaction had not gone to completion. Nevertheless, the presence of 1 mole percent by quaternary phosphonium chloride salt groups was adequate to permit preparation of the stable emulsifier- free latex, and was adequate to provide ionic crosslinking in deposited polymer films. The presence of the benzylic chlorine would permit permanent covalent crosslink to be formed in many ways or permit other reactions to be run on this useful pendant functionalized polymer.
  • Examples 2 and 3 all show that the backbone saturated pendant functionalized copolymers of this invention containing various cationic pendant functionality are readily prepared by following the procedures of this invention and that they have useful combinations of properties for various applications.
  • the pendant cationic groups are capable of imparting self-emulsification properties to make possible the facile preparation of emulsifier-free cationic latices and the pendant cationic groups self-associate in dry deposited films to provide ionic crosslinks which are reversible by proper solvation.
  • Two classes of cationic pendant functionalized copolymers have been exemplified (i. e. quaternary ammonium salts and quaternary phosphonium salts) , but others such as the sulfonium salts , for example, using thioethers as the nucleophile as shown below are also possible:
  • cationic pendant functionalized polymers can be varied and controlled by the type of cationic group attached as well as by the R groups present and the counterion so that a broad range of properties is possible.
  • the quaternary salts with other R groups are readily prepared to impart modified properties .
  • the ionic associations become stronger and more difficult to disrupt, but hydrophobicity improves as the R groups become larger.
  • Properties are also strongly influenced by the counterion (i. e. chloride, bromide, bisulfate, etc. ) .
  • S-isothiouronium salts are strongly dependent upon whether thiourea itself is used (as used in our examples) or substituted thioureas are used as the nucleophile.
  • Strength of the ionic crosslinks and hydrogen bonding properties are both diminished as substituted thioureas containing more and longer R groups are used to prepare the salts.
  • the R groups themselves can contain other functionality to prepare cationic salts containing other useful functionality as for example, using triethanol amine as the nucleophile to prepare a pendant functionalized polymer containing quaternary ammonium salt groups with hydroxy functionality to permit further reactions or promote adhesion or di ⁇ persant action, etc.:
  • pendant dithiocarbamate ester functionality was attached to a random isobutylene/para-methylstyrene/para-bromomethylstyrene base terpolymer by nucleophilic substitution using sodium diethyl dithiocarbamate as the nucleophilic reagent.
  • the base terpolymer containing the reactive electrophilic benzylic bromines was prepared as already outlined.
  • the starting polymer was prepared as in Example 1; it contained 3.3 mole percent para-methylstyrene with a viscosity average molecular weight of 68,000.
  • the polymer was radically brominated using light initiation at 40oC as a 15 percent solution in hexane to give a base terpolymer with a viscosity average molecular weight of 65,000 and containing 4.3 weight percent bromine.
  • the base terpolymer composition was 96.7 mole percent isobutylene, 2.6 mole percent para-bromomethylstyrene, and 0.7 mole percent para-methylstyrene. There was some dibrominated para-methylstyrene present because of the high bromination level achieved.
  • nucleophilic substitution reaction 200 g of the base terpolymer was dissolved in 2100 g of toluene in a 5 1 resin flask under nitrogen to form an 8.7 weight percent solution. Then 22 g of sodium diethyl dithiocarbamate dissolved in 700 g of isopropyl alcohol was added slowly with stirring at room temperature to give a 6.6 weight percent polymer solution in a 75/25 toluene/isopropanol solvent blend with 1.2 moles per mole of Br of the nucleophilic reagent. The solution was heated with stirring under N 2 at 80oC for 6 hours to complete the nucleophilic substitution reaction before being cooled.
  • the proton NMR spectrograph confirmed the chemical analysis in showing the quantitative conversion of benzylic bromine functionality to pendant dithiocarbamate ester functionality.
  • a base isobutylene/para- methylstyrene/para-bromomethylstyrene terpolymer was prepared and converted via a sequential reaction route to a copolymer containing pendant dithiocarbamate ester functionality without separate isolation and recovery of the intermediate base terpolymer.
  • This sequential reaction route which avoids recovery of the intermediate base terpolymer is of course economically advantageous .
  • Example 2A was dissolved in hexane under nitrogen to form a 17 weight percent solution with 8 percent by weight of ATOMITE CaCO 3 stirred in suspension as an acid scavenger to give an opaque white slightly viscous solution which was heated with stirring under nitrogen to
  • This mixed functionality polymer was stable without any added antioxidants and was vulcanizable with promoted zinc oxide and/or conventional sulfur vulcanization systems. It also showed good covulcanization in blends with natural rubber. Films of this copolymer crosslinked on exposure to UV-radiation as opposed to the degradation on exposure to UV-radiation as opposed to the degradation normally experienced with high isobutylene containing polymers exposed to UV-radiation.
  • the crosslinking under irradiation is attributed to the ready ability of the dithiocarbamate ester functionality to form stable radicals under irradiation to permit radical crosslinking and other radical chemistry reactions to occur rather than backbone cleavage as normally occurs with isobutylene based polymers:
  • the bromination reaction was over in ⁇ 5 minutes and after removal of a sample for characterization of the base terpolymer, 30 g of sodium diethyl dithiocarbamate (0.9) moles/mole of bromine) dissolved in 600 g of isopropanol (to give an 83/17 hexane/ isopropanol solvent blend) was added to effect the nucleophilic substitution reaction.
  • the solution was stirred hot at 60 o C for 1/2 hour to complete the reaction. After the solution was cooled and acid washed, the polymer was recovered by alcohol precipitation as in Example 4B.
  • the sequential reactions proceeded as already outlined. Analysis as summarized below showed on intermediate base terpolymer with 2.2 weight percent bromine and a final pendant mixed functionalized product with 0.7 mole percent benzylic bromine and 0.7 mole percent dithiocarbamate ester functionality.
  • Dithiocarbaaate Ester These examples show that pendant dithiocarbamate ester functionality is readily introduced into the base terpolymer of this invention by a nucleophilic substitution reaction. Stable mixed functionality polymers containing both benzylic bromine and dithiocarbamate ester functionality can be made at any desired ratio of the functionalities and an economical sequential reaction route can be utilized.
  • pendant cinnamate ester functionality was attached to a random isobutylene/para- methylstyrene/ para-bromomethylstyrene base terpolymer by nucleophilic substitution using a cinnamic acid salt as the nucleophilic reagent.
  • the base terpolymer used in this example was identical to that used in Examples 4A and 4B and contained 0.9 mole percent brominated para- methylstyrene, 1.4 mole percent para-methylstyrene, and 97.7 mole percent isobutylene with an My of 135,000.
  • the final product following three hours of reflux contained 0.8 mole percent cinnamate ester and 0.1 mole percent benzylic bromine.
  • the nucleophilic substitution reaction was about 90 percent complete:
  • pendant fatty acid ester functionality was attached to a random isobutylene/para- methylstyrene/ para-bromomethylstyrene base terpolymer by nucleophilic substitution using a commercial C 18 fatty acid in linolenic acid (INDOSTRENE 120 from Witco Corporation) as the fatty acid.
  • the base terpolymer used had a Mooney viscosity of 30 and contained 2 mole percent para-bromomethylstyrene, 5 mole percent para-methylstyrene, and 93 mole percent isobutylene.
  • the emulsion was refluxed for 2 hours with samples being removed at the reflux point, after 1/2 hour and after 1 hour of refluxing to monitor the progress of the reaction.
  • the reaction solution became clearer with water droplets being distilled over into the condenser.
  • the final solution was translucent with a light yellow color.
  • the reaction samples and final reaction effluent were given acidic, basic, and then neutral water washes before the polymer was precipitated in isopropanol and vacuum oven dried as before. Analysis below, as in Example 5A, for bromine remaining in the starting polymer indicates that the nucleophilic substitution with the C 18 fatty acid was faster than with the cinnamic acid salt and was essentially complete in one hour.
  • Zinc Oxide - 3.00 The presence of unsaturation in the pendant fatty acid side chains thus permits conventional sulfur vulcanization systems to be employed to vulcanize the functionalized ester derivative of this example.
  • the pendant unsaturation is also useful in permitting covulcanization with the high unsaturation general purpose rubbers such as natural rubber or SBR. Testing of sulfur vulcanized specimens of this ester derivative in a standard ozone resistance test showed that they retained the outstanding ozone resistance characteristic of the saturated base terpolymer vulcanizates.
  • the pendant unsaturation in the side chain thus imparts conventional sulfur vulcanization activity without adversely affecting ozone resistance.
  • pendant fatty acid ester functionality in which the fatty acid contained conjugated unsaturation was attached to the base terpolymer.
  • the fatty acid used was derived from Tung oil and was high in eleostearic acid.
  • the base terpolymer had a Mooney viscosity of 32 and contained 3.6 weight percent bromine, 2.2 mole percent para- bromomethylstyrene, 2.7 mole percent para-methylstyrene, and 95.1 mole percent isobutylene.
  • the NMR spectrum shows a resonance due to the benzylic ester protons at 5.08 ppm, some residual resonance at 4.47 ppm due to remaining benzylic bromide, and a series of resonances at 5.3 - 6.4 ppm due to the olefinic protons of the C 18 acid (with the conjugated unsaturation resonances being the high field resonances at >5.9 ppm).
  • the final product contained 1.9 mole percent ester with 0.2 mole percent benzylic bromide remaining. It was completely soluble in toluene with a
  • this functionalized polymer showed good stability with no tendency to crosslink during drying or storage.
  • the attached conjugated unsaturation permitted facile vulcanization and covulcanization with unsaturated rubbers using sulfur vulcanization systems.
  • the conjugated unsaturation also provided good crosslinking under electron beam irradiation and oxidative surface curing upon outdoor exposure to sunlight. This is a highly desirable property in exterior coatings such as roof coatings.
  • the conjugated unsaturation is also very active in radical reactions thus permitting grafting reactions with free radical polymerizable monomers. This highly active Tung oil acid ester derivative is useful in a wide range of applications.
  • nucleophilic substitution reactions with various carboxylic acids could be used to attach many other functional side chains such as hydroxy using ricinoleic aoid, etc.
  • UV photoinitiator benzophenone was incorporated into the terpolymer as a 4- benzoylbenzoate ester derivative.
  • base terpolymer Mooney viscosity - 32, 1.88 weight percent bromine
  • a toluene solution of tetrabutylaamonium 4-benzoylbenzoate was prepared under nitrogen by dissolving 0.51 g 4-benzoylbenzoic acid and tetrabutyl amaonius hydroxide (2.2 ml, 1 M in methanol) in 25 ml toluene, then reducing this solution by one-half its volume.
  • the functionalized polymer showed good crosslink response at low absorbance levels as seen in Table I. Examples 8-11
  • Example 8 2-benzoylbenzoate (Example 9) , 4- hydroxybenzophenone (Example 10) , and anthraquinone-2- carboxylate (Example 11) derivative functionalized copolymers were prepared in nucleophilic substitution reactions according to the procedure in Example 7 to incorporate the photoinitiators benzophenone, hydroxybenzophenone or anthraguinone.
  • the base isobutylene/para-methylstyrene/para-bromomethylstyrene terpolymer was the same throughout, similarly prepared to the procedure in Example 1, and having a Mooney viscosity of 32 and 1.88 weight percent bromine.
  • the UV- functionalized copolymers comprised 0.75 mole percent ester.
  • 2.0 g base terpolymer was utilized.
  • the initial quantity of 3-benzoylbenzoic acid reactant was 0.11g followed by an additional 0.02g to neutralize litmus paper.
  • the quantity of 2-benzoylbenzoic acid utilized was the same as for 3-benzoylbenzoic acid.
  • the quantity of anthraquinone-2-carboxylic acid utilized was 0.12g and the quantity of 4- hydroxybenzophenone was 0.09g.
  • Example 5A To the cinnamate functionalized copolymers similarly produced in Example 5A, tests were performed to determine the level of gel formation at variable coating thickness and UV-exposure.
  • the base terpolymer had a M v of about 135,000 and was made up of 2.3 mole percent para-methylstyrene including 0.9 mole percent brominated para-methylstyrene. It was converted via bromination and subsequent nucleophilic displacement into the polymer of Example 5A which contained 0.1 mole percent para-bromomethylstyrene and 0.8 mole percent cinnamate ester.
  • the cinnamate functionalized copolymer was crosslinked via a UV initiated 2+2 photocycloaddition with the results appearing in Table II.
  • Coatings of the functionalized product from Example 7 were exposed to varying doses of UV radiation to determine the ease and degree of crosslinking in coatings (1.5 mil) prepared from both unblended functionalized copolymer and a PSA composition containing a 1 : 1 admixture of the copolymer product with the tackifier resin ECR-143H.
  • Example 1 Starting with an isobutylene/para-methyl- styrene/para-bromomethylstyrene base terpolymer as outlined in Example 1, the dithiocarbamate derivative was prepared similar to the steps in Example 5A.
  • a PSA formulation was prepared by blending the copolymer derivative in a 1:1 ratio with the ECR-143H tackifier resin.
  • the copolymer had a Mooney viscosity of 27.5 and comprised 2.4 mole percent para-methylstyrene. It was converted into 0.75 mole percent dithiocarbamate ester with a trace of the bromide and the remaining constituent isobutylene (97.6 mole percent).
  • MYLAR coatings (1.5 mil) were prepared and adhesive tests conducted to compare adhesive strength to cohesive strength properties for the UV-crosslinked and uncrosslinked coatings. Data shown in Table IV indicate improved cohesive strength of a PSA composition containing the dithiocarbamate derivative without excessive loss of tack.
  • the base terpolymer had a M v of about 135 , 000 and comprised 2.4 mole percent para- methylstryene. It was converted to 0.8 mole percent tung oil ester with 0. 14 mole percent unconverted para- bromomethyl styrene and the remainder isobutylene (97.6 mole percent) . Coatings were prepared on MYLAR backing to conduct adhesive tests following EB-crosslinking. Adhesion tests were made to stainless steel substrates unless otherwise noted.
  • PSA systems were prepared utilizing the 4-benzoylbenzoate functionalized copolymer.
  • Example 7 and the 4-hydroxybenzophenone derivative.
  • Example 10 with the objective to determine crosslinking response of the functionalized copolymers in the presence of different tackifiers.
  • Samples were blended 50: 50 UV-reactive functionalized copolymer:tackifier and toluene extractions were performed on the irradiated PSA formulations. Since the polymer concentration in each sample was about 50 percent, complete conversion of the polymer to insoluble material would be represented as 50% gel.
  • Example 7 and Example 10 gave comparable conversions to gel in the presence of tackifier. This photochemistry was independent of tackifier saturation with the crosslinking response being substantially equivalent for both hydrogenated and nonhydrogenated tackifiers. This was demonstrated by the high conversions to gel for Examples 35 and 37 where the tackifier, ECR-143, was not hydrogenated. Examples 41-43
  • PSA systems were prepared as in the previous Examples 32-40 utilizing the 4-benzoylbenzoate functionalized copolymer from Example 7 and the tackifier resin was ECR-143H. Several adhesive tests including SAFT were then performed on film samples at varying levels of UV exposure.
  • PSA systems were prepared as in the previous
  • UV exposure was 0.2 J/cm 2 .
  • Adhesion tests were performed on coated samples with procedures and description of tests described as before.
  • Example 10 the 4-hydroxybenzophenone functionalized copolymer from Example 10 was utilized as corrosion barrier coatings on galvanized steel plates. Initially, the Example 10 polymer was dissolved in toluene then coated onto 2 galvanized steel plates. Evaporation of the solvent provided a 1 mil thick film coating. One plate was crosslinked by exposure to 0.24 J/cm 2 UV-radiation and the other was not crosslinked. After 10 days immersion in a 5 percent NaCl salt bath, the plates were observed for corrosion resistance .
  • Example 10 the 4-hydroxybenzophenone functionalized copolymer from Example 10 was utilized as a coating in a lithographic application. A 1 mil film was coated onto a cardboard substrate as described in
  • Examples 48-49 The dried film was irradiated with 0.25 J/cm 2 UV light to produce a stenciled image in the coating. The image was revealed by developing in toluene to remove the uncrosslinked polymer.

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