Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/12—Bonding of a preformed macromolecular material to the same or other solid material such as metal, glass, leather, e.g. using adhesives
  • C08J5/124—Bonding of a preformed macromolecular material to the same or other solid material such as metal, glass, leather, e.g. using adhesives using adhesives based on a macromolecular component
  • C08J5/127—Aqueous adhesives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
  • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
• • 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
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/02—Emulsion paints including aerosols
  • C09D5/024—Emulsion paints including aerosols characterised by the additives
• • 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
  • C09J201/00—Adhesives based on unspecified macromolecular compounds
  • C09J201/02—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
  • C09J201/06—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups containing oxygen atoms
  • C09J201/08—Carboxyl groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
  • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
  • C08L2666/14—Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
  • C08L2666/20—Macromolecular compounds having nitrogen in the main chain according to C08L75/00 - C08L79/00; Derivatives thereof

Definitions

• This invention belongs to the field of emulsion chemistry.
• it relates to stable waterbome polymer compositions useful in a variety of adhesive formulations.
• aqueous coating compositions continue to replace traditional organic solvent-based coating compositions, as the use of solvents other than water is becoming more and more undesirable due to solvent expense and the cost and hazards involved in controlling solvent vapors. Paints, inks, sealants, and adhesives such as pressure sensitive or laminating adhesives, for example, previously formulated with organic solvents, are now formulated as aqueous compositions. This reduces potentially harmful exposure to volatile organic compounds (NOC's) commonly found in solvent- based compositions.
• NOC's volatile organic compounds
• aqueous coating compositions must meet or exceed the performance standards expected from solvent-based compositions.
• the need to meet or exceed such performance standards places a premium on the characteristics and properties of waterbome polymer compositions used in aqueous coating compositions, such as adhesives.
• Waterbome polymers having various functional groups have been used to impart and achieve desired properties to a particular coating composition.
• a coating composition should exhibit good film formation, print and block resistance, as well as adhesion and tensile properties.
• Polymers having acetoacetoxy- and enamine-functional groups represent one example of waterbome polymers which have such properties, may carry different functional groups, and are useful in aqueous coating compositions.
• U.S. Patent 5,296,530 discloses a quick-curing coating prepared from a polymer having acetoacetyl groups, in which substantially all of the acetoacetyl groups have been converted to enamine functional groups. This conversion occurs, for example, by treatment with ammonia or a primary amine. Coatings so prepared cure more quickly under sunlight or ultraviolet light than coatings which contain the acetoacetyl functional polymer but which have not been converted to an enamine form.
• U.S. Patents 5,484,975 and 5,525,662 describe the preparation of polymers containing functional acetoacetate groups and then, following the polymerization, reacting the acetoacetate group with a functional amine to form an enamine.
• the resulting polymers are reported to have a variety of uses including coatings, sealants, adhesives, and saturant applications.
• U.S. Patent 5,498,659 discloses polymeric formulations comprising an aqueous carrier, at least one polymeric ingredient, a non-polymeric polyfunctional amine, and a base.
• the polymeric ingredient has both acid- functional and acetoacetoxy-type functional moieties.
• the aqueous polymeric formulations produce crosslinked polymeric surface coatings on a substrate.
• Japanese Patent Application No. 61-21171 describes a fast-curing adhesive of two separate liquids.
• the first liquid is an aqueous solution and/or aqueous emulsion of a polymer compound containing an acetoacetyl group.
• the second liquid consists of polyethylenimine.
• the adhesive in order to achieve fast-curing adhesive properties, the adhesive must be applied as two separate liquids.
• U.S. Patent No. 5,362,816 describes a pressure-sensitive adhesive containing an acetoacetate functional monomer in a low Tg emulsion polymer.
• the pressure sensitive adhesive is a polymer prepared by free radical emulsion polymerization having a Tg below about 0 °C and has pendent acetoacetate functional groups.
• the pendent acetoacetate groups are reacted with ammonia or a primary amine to form an enamine-containing composition at a pH greater than 9.
• U.S. Patent No. 5,278,227 describes inherently tacky, emulsion pressure-sensitive adhesive polymers prepared from a specified mixture of monomers.
• the monomer mixture comprises about 35 to about 65 percent by weight alkyl acrylates, about 15 to about 35 percent vinyl esters, about 20 to about 35 percent by weight diesters of a dicarboxylic acid, and up to about 5 percent by weight of an unsaturated carboxylic acid.
• the glass transition temperature of the polymer is less than about -30 °C.
• This invention provides stable waterbome polymer compositions which are stabilized against gelling, comprising a stable waterbome polymer composition comprising an acetoacetoxy-type functional polymer, a poly(alkylenimine), and a nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of at least about 17.5.
• a stable waterbome polymer composition comprising an acetoacetoxy-type functional polymer, a poly(alkylenimine), and a nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of at least about 17.5.
• HLB hydrophilic-lipophilic balance
• stable waterbome polymer compositions are useful in a variety of coating formulations such as, for example, paints, inks, sealants, and adhesives.
• the stable waterbome polymer compositions of the invention provide adhesion and crosslinking in the final film or coating.
• the film or coating may be cured at ambient temperatures or may be thermally cured.
• Methods of preparing stable waterbome polymer compositions are also disclosed, along with methods of stabilizing latex compositions against gelling upon addition of a poly(alkylenimine).
• the stable waterbome polymer compositions according to the invention have beneficial adhesive and shear strength properties.
• Particularly suitable adhesive compositions comprise a mixture of (a) the stable waterbome polymer composition discussed above and (b) a non-acetoacetoxy functional polymer.
• the waterbome polymer composition (a) has a glass transition temperature (Tg) of greater than about 0 °C and the non-acetoacetoxy functional polymer (b) has a Tg of from about 20 °C or lower.
• the stable waterbome polymer compositions of the present invention can be used in combination with polymer compositions which lack good shear and/or cohesiveness to provide adhesive compositions with improved shear and cohesiveness. Accordingly, the invention also relates to a method for improving the shear and/or cohesion of an adhesive composition comprising an effective amount of a stable waterbome polymer composition (a).
• the adhesive compositions according to the invention are particularly suitable for use as pressure sensitive and laminating adhesives. Accordingly, in another embodiment, the invention relates to pressure sensitive adhesives and laminating adhesives comprising the adhesive compositions of the invention discussed above. The invention also relates to improved methods employing laminating adhesives and pressure sensitive adhesives.
• the invention relates to an improved method for laminating a first substrate to a second substrate comprising applying an adhesive composition to a surface of the first substrate and pressing the surface of the first substrate against the second substrate.
• the adhesive composition comprises a mixture of (a) a stable waterbome polymer composition having a Tg of greater than about 0 °C and comprising an acetoacetoxy-type functional polymer, a poly(alkylenimine), and a nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of at least about 17.5 and (b) a non-acetoacetoxy functional polymer having a Tg of about 20 °C or lower.
• the adhesive composition may be simultaneously applied to both substrates while the substrates are pressed together.
• the invention relates to an improved method of making a substrate bearing a coating of a pressure sensitive adhesive on at least one surface thereof comprising applying an adhesive composition to a surface of a substrate, the improvement wherein the adhesive composition comprises a mixture of (a) a stable waterbome polymer composition having a Tg of greater than about 0 °C and comprising an acetoacetoxy-type functional polymer, a poly(alkylenimine), and a nonionic surfactant having hydrophilic- lipophilic balance (HLB) of at least about 17.5 and (b) a non-acetoacetoxy functional polymer having a Tg of about 0 °C or lower.
• the adhesive composition comprises a mixture of (a) a stable waterbome polymer composition having a Tg of greater than about 0 °C and comprising an acetoacetoxy-type functional polymer, a poly(alkylenimine), and a nonionic surfactant having hydrophilic- lipophilic balance (HLB) of at least about 1
• the present invention provides stable waterbome polymer compositions, that is, compositions containing a polymer and water.
• Waterbome polymer compositions include, but are not limited to, latexes, dispersions, microemulsions, or suspensions.
• Waterbome polymer compositions of the present invention are stable and may be stored at room temperature or moderately above room temperature (e.g., about 50 to 60°C) and provide adhesion and crosslinking upon film formation when applied to a substrate.
• a film or coating formed with polymers of the invention may be cured at room temperature (ambient cure) or at elevated temperatures (thermal cure).
• the polymers used to prepare the waterbome polymer composition of the present invention are generally prepared as particles.
• the particles may be structured or unstructured. Structured particles include, but are not limited to, core/shell particles and gradient particles.
• the average polymer particle size may range from about 25 to about 600 nm.
• the polymer particles generally have a spherical shape.
• the generally spherical polymeric particle may have a core portion and a shell portion.
• the core/shell polymer particles may also be prepared in a multilobe form, a peanut shell, an acom form, or a raspberry form. It is further preferred in such particles that the core portion comprises about 20 to about 80 percent of the total weight of said particle and the shell portion comprises about 80 to about 20 percent of the total weight volume of the particle.
• Enamine- functional polymers represent a preferred embodiment of polymers used to form the stable waterbome polymer compositions of the present invention.
• Enamine-functional polymers may be prepared by reacting a polymer having acetoacetoxy groups with ammonia or a primary or secondary amine.
• the primary or secondary amine may be a monoamine compound or a polyamine compound.
• Preferred amines include, for example, triaminononane, H 2 N(CH 2 ) 3 CH(CH 2 NH 2 )(CH 2 ) 4 NH 2 (CAS Registry No. 1572-55-0), available from Monsanto, or, as described below, polyethylenimine, (PEI).
• PES polyethylenimine
• the enamine functionality serves to further stabilize the acetoacetoxy-groups and protect them from hydrolysis.
• Enamine-functional polymers have been described in Moszner et al., Polymer Bulletin 32, 419-426 (1994); European Patent Application No. 0 492 847 A2; U.S. Patent No. 5,296,530; and U.S. Patent No. 5,484,849.
• Acetoacetoxy-type functional polymers useable in the present invention may be prepared by free radical emulsion polymerization of vinyl monomers having an acetoacetoxy functionality such as those of Formula (I) below with other vinyl monomers. This combination of monomers provides water-based dispersion of polymer particles where the polymer has pendant acetoacetoxy groups.
• a "vinyl" monomer is an ethylenically unsaturated monomer.
• a pendant acetoacetoxy group is not strictly limited to those at the termini of the polymer.
• Pendant acetoacetoxy groups also include groups attached to the polymer's backbone and available for further reaction.
• Acetoacetoxy-type functional polymers preferably contain about 0.5 to about 30 weight percent of vinyl monomers having acetoacetoxy-type functionality such as those of Formula I, and about 99.5 to about 70 weight percent of other vinyl monomers, preferably alkyl (meth)acrylates having 1 to 18 carbons. The weight percentage is based on the total amount of monomers in the composition. More preferably, the stabilized polymer has about 1 to about 15 weight percent acetoacetoxy monomers, and about 99 to about 85 weight percent of other vinyl monomers. Aspects of this emulsion polymerization and preferred embodiments are discussed below beginning with vinyl monomers as in Formula (I) which have an acetoacetoxy-type functionality.
• R 1 -CH C(R 2 )C(O)-X 1 -X 2 -X 3 -C(O)-CH 2 -C(O)-R 3 (I)
• R 1 is a hydrogen or halogen.
• R 2 is a hydrogen, halogen, C ⁇ -C 6 alkylthio group, or C ⁇ -C 6 alkyl group.
• R 3 is a C ⁇ -C 6 alkyl group.
• X 1 and X 3 are independently O, S, or a group of the formula -N(R')-, where R' is a C ⁇ -C 6 alkyl group.
• X 2 is a C 2 -C ⁇ 2 alkylene group or C -C ⁇ 2 cycloalkylene group.
• the alkyl and alkylene groups described here and throughout the specification may be straight or branched groups.
• Preferred monomers of Formula (I) are acetoacetoxyethyl methacrylate, acetoacetoxyethyl acrylate, acetoacetoxy(methyl)ethyl acrylate, acetoacetoxypropyl acrylate, allyl acetoacetate, acetoacetamido-ethyl
• Acetoacetoxyethyl methacrylate represents a particularly preferred monomer of Formula
• Suitable other vinyl monomers which may be reacted with the vinyl monomers having acetoacetoxy-type functionality include, but are not limited to, methyl acrylate; methyl methacrylate; ethyl acrylate; ethyl methacrylate; butyl acrylate; butyl methacrylate; isobutyl acrylate; isobutyl methacrylate; ethylhexyl acrylate; ethylhexyl methacrylate; octyl acrylate; octyl methacrylate; styrene; ⁇ -methyl styrene; glycidyl methacrylate; carbodiimide methacrylate; Ci-Cis alkyl crotonates; di-n-butyl maleate; dioctylmaleate; allyl methacrylate; di-allyl maleate; di-allylmalonate; methoxybutenyl methacrylate
• R is independently hydrogen or an alkyl group of up to 12 carbon atoms.
• Particular monomers of Formula (II) include
• CH 2 CH-O-C(O)-CH 3
• CH 2 CH-O-C(O)-C(CH 3 ) 3
• Vinyl ester monomers also include vinyl esters of vinyl alcohol such as the VEOVA series available from Shell Chemical Company as VEOVA 5, VEOVA 9,
• VEOVA 10, and VEOVA 11 products See O.W. Smith, M.J. Collins, P.S.
• Optional monomers that may be incorporated into the polymer include styrene, butyl styrene, vinyl toluene, oc -methyl styrene, (meth)acryl-amide,
• (meth)acrylonitirle vinyl acetate, and vinyl esters of acids other than acetic acid, itaconic anhydride, maleic anhydride, vinyl formate, and salts of 2- sulfoethyl (meth)acrylate.
• the acetoacetoxy functional polymer may also incorporate nitrogen-containing, vinyl monomers known to promote wet adhesion.
• exemplary wet adhesion monomers include, for example, t-butylaminoethyl methacrylate; dimethylaminoethyl methacrylate; diethyl- aminoethyl methacrylate; N,N-dimethylaminopropyl methacrylamide;
• N-(2-methacryloyloxyethyl)ethylene urea is available from
• acid vinyl monomers may also be used to prepare acetoacetoxy emulsion polymers according to the invention.
• Such acid vinyl monomers include, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and 2-acrylamido-2 -methyl- 1- propanesulfonic acid (sodium, potassium, or ammonium salts).
• these monomers are used in small amounts.
• the amount of acid vinyl monomers may range, for example, from 0 to 5 phr. Larger amounts of acid vinyl monomers may be used to achieve a desired effect, such as increased viscosity.
• the acetoacetoxy polymer may be prepared using emulsion polymerization techniques known in the art.
• the acetoacetoxy polymer may, as is known in the art, be prepared using free radical emulsion polymerization techniques which yield structured or unstructured particles.
• structured particles include, for example, core/shell particles, raspberry particles, and gradient particles.
• Chain transfer agents, initiators, reducing agents, catalysts, and surfactants known in the art of emulsion polymerization may be used to prepare the polymers.
• Chain transfer agents may optionally be added, in an amount up to about 2 weight percent based on total monomer content, to control the molecular weight of the polymer.
• Use of chain transfer agents may be preferred when it is desired to obtain low molecular weight polymers.
• Exemplary chain transfer agents are butyl mercaptan, mercaptopropionic acid, 2-ethylhexyl mercaptopropionate, dodecylmercaptan, n-butyl mercaptopropionate, octyl mercaptan, isodecyl mercaptan, octadecyl mercaptan, mercaptoacetic acid, allyl mercaptopropionate, allyl mercapto-acetate, crotyl mercaptopropionate, crotyl mercaptoacetate, and the reactive chain transfer agents taught in U.S. Patent No. 5,247,040, incorporated here by reference.
• Typical initiators include hydrogen peroxide, sodium, potassium or ammonium peroxydisulfate, dibenzoyl peroxide, lauryl peroxide, ditertiary butyl peroxide, 2,2'-azobisisobutyronitrile, t-butyl hydroperoxide, benzoyl peroxide, and the like.
• Suitable reducing agents are those which increase the rate of polymerization and include for example, sodium bisulfite, sodium hydrosulfite, sodium formaldehyde sulfoxylate, ascorbic acid, isoascorbic acid, and mixtures thereof.
• Polymerization catalysts are those compounds which increase the rate of polymerization and which, in combination with the above described reducing agents, may promote decomposition of the polymerization initiator under the reaction conditions.
• Suitable catalysts include transition metal compounds such as, for example, ferrous sulfate heptahydrate, ferrous chloride, cupric sulfate, cupric chloride, cobalt acetate, cobaltous sulfate, and mixtures thereof.
• Peroxide-iron and peroxide-sulfite redox catalysts may also be used.
• Crosslinking agents may optionally be added, in an amount up to about 2 weight percent, based on total monomer content, to control the molecular weight of the polymer.
• Use of crosslinking agents may be preferred when it is desired to obtain high molecular weight polymers.
• Useful crosslinkers include trimethylolpropane tri(meth)acrylate, 1 ,6-hexanediol di(meth)acrylate, allyl methacrylate and the like.
• Any conventional polymerization surfactant may be used to form the polymers of the present invention.
• Useful surfactants include, but are not limited to, ionic and nonionic surfactants such as alkyl polyglycol ethers; alkyl phenol polyglycol ethers; alkali metal ammonium salts of alkyl, aryl or alkylaryl sulfonates, sulfates, phosphates, and the like, and reactive anionic or nonionic surfactants possessing styrene or allyl groups.
• ionic and nonionic surfactants such as alkyl polyglycol ethers; alkyl phenol polyglycol ethers; alkali metal ammonium salts of alkyl, aryl or alkylaryl sulfonates, sulfates, phosphates, and the like, and reactive anionic or nonionic surfactants possessing styrene or allyl groups.
• Sulfonate containing surfactants such as sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, or the diesters of sodiosulfosuccinic acid such as sodium dioctylsulfo-succinate, and alpha olefin sulfonates are suitable.
• surfactants such as sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, or the diesters of sodiosulfosuccinic acid such as sodium dioctylsulfo-succinate, and alpha olefin sulfonates are suitable.
• persulfate catalysts are used, in-situ- generated oligomers with sulfate end groups may act as surfactants.
• useful surfactants may include some of the same surfactants listed below for post polymerization addition, incorporation of these particular surfactants into the polymerization process is a less preferred method of stabilizing the polymer against gelling upon addition of poly(alkylenimine) and upon adjustment of pH of the polymer. Although they may be used in the emulsion polymerization process, they may contribute to processing problems such as increased particle size and increased amounts of coagulum in the polymer.
• the type and amount of surfactant used in the polymerization process depends on the specific composition, reaction conditions, and the desired final particle size, as is known in the art.
• Water-dispersible and water-soluble polymers may also be employed as surfactants/stabilizers in the water-based latexes of the invention.
• polymeric stabilizers include water-dispersible polyesters as described in U.S. Patent Nos. 4,946,932 and 4,939,233; water-dispersible polyurethanes as described in U.S. Patent Nos. 4,927,876 and 5,137,961; alkali-soluble acrylic resins as described in U.S. Patent No. 4,839,413; and hydroxyethyl cellulose, as described in U.S. Patent No. 3,876,596 and British Patent 1,155,275.
• the acetoacetoxy functionality in the polymer may be present as free acetoacetoxy groups or as derivatives of those groups such as, for example, an enamine group or acetoacetamide group.
• the acetoacetoxy-functional polymer may contain both free acetoacetoxy groups and acetoacetoxy derivatives.
• enamine-functional polymers may be prepared by addition of a primary or secondary amine to the acetoacetoxy polymer.
• Preferred amines are poly(alkyleneimines).
• Poly(alkylenimines) for use in the invention may have a weight average molecular weight of about 200 to about 750,000.
• the poly(alkylenimine) is preferably a poly(ethylenimine) (PEI) and more preferably PEI having a weight average molecular weight of about 800 to about 25,000.
• the PEI may contain primary, secondary, and tertiary amine groups, for example, in a ratio of 1.5 : 1.4: 1.0, respectively.
• Such PEI compounds are commercially available from BASF Corporation as LUPASOLTM G-35 poly(ethylenimine).
• the content of polyethylenimine can vary from 0.5 to 25 weight percent based on the dry weight of the acetoacetoxy polymer. More preferably, the content of polyethylenimine can vary from 2 to 12 weight percent based on the dry weight of the acetoacetoxy polymer.
• poly(alkylenimines), particularly poly(ethylenimine) are known to flocculate latexes, and are actually sold for that purpose.
• the pH of the prepared latex is normally greater than 11, much too high for many commercial applications. After addition of a poly(alkylenimine), upon adjustment of the pH of the latex to a pH of less than about 10, the latex normally gels.
• the thus formed waterbome polymer compositions may be stabilized against gelling due to the addition of poly(alkylenimine), by post polymerization addition of a surfactant.
• the surfactant is a nonionic surfactant having a hydrophilic-lipophilic (HLB) value of at least about 17.5.
• HLB hydrophilic-lipophilic
• the surfactant may be added either prior to, with or after addition of the poly( alkyl enimine), but before adjusting the pH of the polymer.
• the choice of surfactant for post polymerization addition to the emulsion polymer does not depend on the chemical structure of the surfactant, but only on the surfactant having an HLB value of at least about 17.5.
• the addition of a poly (alkyleneimine), particularly poly(ethylenimine), to polymers to which surfactants having an HLB of at least about 17.5 has been added does not cause flocculation, but provides a stable, waterbome polymer composition.
• the addition of poly(ethylenimine) may be accomplished by adding, with stirring, poly(ethyl enimine) to an emulsion of the acetoacetoxy polymer to which has also been added a nonionic surfactant having an HLB value of at least about 17.5.
• Sufficient surfactant should be added to stabilize the waterbome polymer composition.
• the surfactant may be added in an amount of from about 0.5 phr to about 5 phr based on dry polymer weight.
• the surfactant may be added, with stirring, with the poly(ethylenimine) or after addition of the poly(ethylenimine); but prior to adjusting the pH of the polymer.
• Other surfactants and property modifying ingredients may also be added that do not impact on the stability of the waterbome composition.
• the pH of the stable waterbome polymer composition of the invention comprising an acetoacetoxy-type functional polymer, a poly(alkylenimine), and a nonionic surfactant may be adjusted by the addition of an acid or buffer.
• buffers such as sodium bicarbonate, ammonium bicarbonate, ammonium dihydrogenphosphate, an ammonium polyacrylate, or a mixture of such buffers may be used.
• the buffer such as ammonium bicarbonate, may generally be added to the stable waterbome polymer composition to adjust and/or buffer the pH of the composition to less than about 10.
• Waterbome polymer compositions having pH values in the range of about 7.0 to about 9.8, preferably about 8.4 to about 9.2, may be achieved using ammonium buffers.
• Buffered compositions of the invention are particularly useful in coating formulations.
• the stable waterbome polymer compositions of the present invention will vary in properties, depending on the end-use application.
• the polymer composition may have a glass transition temperature (Tg) of -50 to +100°C; more preferably, -35 to +50°C.
• Tg glass transition temperature
• the glass transition temperature of the polymer composition may range from about 0 to about 100 °C.
• the weight average molecular weight of the stable waterbome polymers may vary from about 20,000 to 5,000,000 daltons; more preferably from 100,000 to 2,000,000 and most preferably from 200,000 to 1,000,000.
• the molecular weight range may be controlled by reaction conditions, as is known in the art, or by the use of a chain transfer agent or crosslinkers, as discussed above.
• the stable waterbome polymers may be present from about 5 to about 65 weight percent based on dry resin and more preferably from about 25 to about 55 weight percent.
• the examples below illustrate the preparation of polymers and water-based compositions according to the invention.
• the stable waterbome polymers may be in the form of small particle size polymers, such as those ranging from about 25 to about 600 nm and more preferably from about 80 to about 400 nm.
• the stable waterbome polymer compositions are useful in a variety of coating formulations including adhesive compositions.
• the invention also relates to an adhesive composition comprising a mixture of (a) a stable waterbome polymer composition having a Tg of greater than about 0 °C and comprising an acetoacetoxy-type functional polymer, a poly(alkylenimine), and a nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of at least about 17.5 and (b) a non-acetoacetoxy functional polymer having a Tg of about 20 °C or lower.
• HLB hydrophilic-lipophilic balance
• the stable waterbome polymer composition of the invention can be used in combination with polymer combinations which lack good shear and/or cohesiveness to provide adhesive compositions with improved shear and cohesiveness.
• the non- acetoacetoxy functional polymer (b) of the adhesive compositions of the present invention is not particularly limited, so long as it does not react with the poly(alkylenimine) of waterbome polymer composition (a) and is stable at the pH of formulation, which, as discussed above, can vary.
• non-acetoacetoxy functional polymers include, but are not limited to, water dispersible polymers such as polyester-amides, alkyds, polyurethanes, polyamides, acrylics, vinyl polymers, polymers having pendant allyl groups such as described in U.S. Patent No. 5,539,073, styrene-butadiene polymers, and vinylacetate-ethylene copolymers or mixtures thereof.
• Acrylic and vinyl acrylic polymers are the preferred non-acetoacetoxy polymers for use in the present invention.
• Suitable acrylic and vinyl acrylic polymers include, but are not limited to, methyl acrylate; methyl methacrylate; ethyl acrylate; ethyl methacrylate; butyl acrylate; butyl methacrylate; isobutyl acrylate; isobutyl methacrylate; ethylhexyl acrylate; ethylhexyl methacrylate; octyl acrylate; octyl methacrylate; glycidyl methacrylate; carbodiimide methacrylate; allyl methacrylate; methoxybutenyl methacrylate; isobomyl methacrylate; hydroxybutenyl methacrylate; hydroxyethyl (meth)acrylate; hydroxypropyl (meth)acrylate; methacrylamide; acrylamide; butyl acrylamide; ethyl acrylamide; vinyl (meth)acrylate; isoprop
• the glass transition temperature (Tg) of the non-acetoacetoxy functional polymer is not particularly limited and varies depending upon the properties required of the resulting adhesive. Typically, the Tg of the non-acetoacetoxy functional polymer is about 20 °C or less. For example, for pressure sensitive adhesive applications, the Tg of the non-acetoacetoxy functional polymer may be about 0 °C or less, preferably less than about -20 °C. For laminating adhesive compositions, a preferred Tg of the non-acetoacetoxy functional polymer is from about -20 °C to about 20 °C.
• the ratio of the amount of the stable waterbome acetoacetoxy polymer composition (a) to the non-acetoacetoxy functional polymer (b) used in the adhesive compositions of the invention varies depending upon the desired adhesive properties. Generally, this ratio varies from about 1 : 10 to 4: 1.
• the adhesive may comprise between about 2% to about 50% of the stable waterbome acetoacetoxy polymer composition (a) based on the combined weight of the stable waterbome acetoacetoxy polymer composition (a) and the non- acetoacetoxy functional polymer (b).
• the acetoacetoxy polymer composition is present at about 2% to about 35%, and more preferably, between about 2% and about 25%.
• the waterbome polymer composition may comprise between about 2% to about 50% of the stable waterbome acetoacetoxy polymer composition (a) based on the combined weight of the stable waterbome acetoacetoxy polymer composition (a) and the non-acetoacetoxy functional polymer (b).
• the acetoacetoxy polymer composition is present at about 2% to about 35%, and more preferably, between about 2% and about 30%.
• these percentages are merely illustrative and can be affected by dilution of the compositions, for example, with water. Further, the above-mentioned ratios may vary according to the adhesive properties desired.
• adhesive compositions comprising a stable waterbome acetoacetoxy polymer composition of the present invention and a non-acetoacetoxy functional polymer are particularly suitable for use as pressure sensitive adhesives and as laminating adhesives.
• a discussion of pressure sensitive adhesives and their applications may be found in U.S. Patent
• PSAs Pressure-sensitive adhesives
• Many adhesives preferably have a balance of one or more properties such as tackiness at the temperature of use, adhesion (peel resistance), cohesion (shear resistance), elongation, elasticity, color clarity and color stability, and resistance to sunlight and other ultraviolet and degrading radiation sources.
• PSAs are typically applied to a backing as hot melts, polymer solutions or as dispersions of a polymer in an aqueous medium.
• Such solutions and dispersions must possess properties which facilitate their use in the manufacture of PSA-containing articles.
• the melt, solution or dispersion, as well as the polymer per se must adequately wet the backing to assure adequate adhesive distribution, coverage and bonding to the backing.
• additives may be added to the pressure sensitive adhesive compositions of the present invention to the extent that such additives are compatible with the adhesive compositions.
• Suitable additives are taught, for example, by U.S. Patent Nos. 5,122,567, 5,362,816, and 5,821,294, the disclosures of which are herein incorporated by reference.
• Such additives include, but are not limited to, protective colloids, tackifiers, fillers and/or extenders such as dispersible clays, colorants such as pigments and dyes, solvents, thickeners, plasticizers, coalescing agents, preservative agents such as biocides, fungicides, and mildewcides, buffers, agents to adjust pH, surfactants, and catalysts.
• the pressure sensitive adhesive compositions according to the invention can be used to make a substrate bearing a coating of a pressure sensitive adhesive.
• the method comprises applying an adhesive composition to a surface of a substrate, wherein the adhesive composition comprises a mixture of (a) a stable waterbome polymer composition having a Tg of greater than about 0° and comprising an acetoacetoxy-type functional polymer, a poly(alkylenimine), and a nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of at least about 17.5 and (b) a non-acetoacetoxy functional polymer.
• HLB hydrophilic-lipophilic balance
• the pressure-sensitive adhesives of the present invention can be applied to any backing which it is desired to adhere to another surface or article.
• Illustrative backings include flexible and rigid (solid), natural and synthetic materials such as plastics, elastomers, solid metals and foils, ceramics (tiles, glass, and the like), wood, papers and cardboard, leather materials, etc. of essentially any form including films, solid articles, woven and non-woven textile materials, and the like.
• Illustrative uses of such articles include wall coverings (paper, fabric, films, and the like), upholstery items, construction roofing and siding materials, tapes of all varieties (including those having backings comprised of woven or non-woven fabrics, paper, polymeric films, metal foils, foams, etc., including double-faced tapes and so-called transfer tapes), packaging, floor and wall tile, other floor and wall coverings, and paneling, and the like.
• wall coverings paper, fabric, films, and the like
• upholstery items construction roofing and siding materials
• tapes of all varieties including those having backings comprised of woven or non-woven fabrics, paper, polymeric films, metal foils, foams, etc., including double-faced tapes and so-called transfer tapes
• packaging floor and wall tile, other floor and wall coverings, and paneling, and the like.
• Suitable backing and substrate materials can be of essentially any chemical composition and include, for example, metals, ceramics (including glass), and natural and synthetic polar and non-polar materials such as polyolefins, e.g., homopolymers and interpolymers of substituted and nonsubstituted olefinically unsaturated hydrocarbons including ethylene, propylene, styrene, butadiene, dicyclopentadiene, etc., and materials which typically contain polar functional groups such as hydroxy, etheral, carbonyl, carboxylic acid (including carboxylic acid salts), carboxylic acid esters (including thio esters), amides, amines, and the like. Essentially all natural materials include one or more polar functional groups.
• Illustrative are virgin and reclaimed cellulosic fibers such as cotton, paper, wood, coconut fiber, jute, hemp, and the like, and proteinaceous materials such as leather, wool, and other animal fur.
• Illustrative synthetic materials containing polar functional groups are polyesters, polyamides, carboxylated styrene-butadiene polymers, etc., such as Nylon-6, Nylon-66, Nylon-610, "Dacron", “Fortrel”, “Kodel”, “Acrilan”, “Orion”, “Creslan”, “Verel” and “Dynel”.
• Illustrative of other useful materials which are also polar are synthetic carbon, silicon, and magnesium silicate (e.g., asbestos).
• Preferred substrates or backings for the adhesive composition of the present invention are polypropylene, polyethylene, polyethylene terephthalate, and polyvinyl chloride.
• the adhesive compositions of the present invention may be applied to the backing by any one of a variety of conventional coating techniques such as roll coating, spray coating, and curtain coating. They also may be applied to the backing without modification by extrusion coating, coextrusion, and hot melt coating by employing suitable conventional coating devices known for such coating methods. While primers may be employed to pretreat the backing, they are unnecessary in many applications. Dry coating weight (the weight of dry adhesive applied per unit surface area) can vary substantially depending upon the porosity and irregularity of the backing and of the substrate surface to which the backing is to be adhered, and other factors.
• Adequate adhesion in tapes manufactured from continuous sheet polymeric substrates can usually be achieved with dry coating adhesive weights of about 10 to about 20 pounds per 3,000 square feet of treated surface, while coating weights of 20 to about 40 pounds per 3,000 square feet are usually employed for paper-backed tapes such as masking tapes.
• the adhesive compositions of the present invention are also suitable for use as laminating adhesives.
• Adhesive lamination is often used in association with flexible packaging material, but is not limited thereto.
• substrates or backings for the pressure sensitive adhesives may be laminated utilizing the adhesive compositions of the present invention.
• Preferred substrates or backings are polypropylene, polyethylene, polyethylene terephthalate, and polyvinyl chloride.
• a first substrate may be laminated to a second substrate with an adhesive composition of the present invention by applying an adhesive composition to a surface of the first substrate and/or the second substrate and pressing the first and second substrates together.
• the inventive adhesive composition utilized in the laminating process comprises a mixture of (a) a stable waterbome polymer composition having a Tg of greater than about 0 °C and comprising an acetoacetoxy-type functional polymer, a poly(alkylenimine), and a nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of at least about 17.5 and (b) a non-acetoacetoxy functional polymer having a Tg of about 20 °C or lower.
• the adhesive composition may be simultaneously applied to both substrates while the substrates are pressed together.
• the first and second substrates may be pressed together by passing the substrates through a two roll nip.
• the inventive adhesive composition may be injected through an opening of the nip and towards the first and/or second substrate.
• the substrates may be laminated using an "in-line” process, which is generally described, for example, in U.S. Patent No. 5,891,950, the disclosure of which is herein incorporated by reference in its entirety.
• any of the stable waterbome compositions described above for the present invention may be combined with the non-acetoacetoxy-functional polymers described above for use as laminating adhesives. Further, any of the formulating agents described above for the pressure sensitive adhesive compositions may be utilized as part of the inventive laminating adhesive compositions.
• the glass transition temperatures (Tg) for the polymer compositions described below were measured using a "second cycle” test as is known to those skilled in the art.
• the glass transition temperature is measured a first time according to standard methods. The sample is cooled back to the starting point, and the glass transition temperature is then determined a second time. This second measurement is often referred to as a "second cycle glass transition temperature.”
• the reactor configuration was a 4 liter jacketed kettle held at 80°C with circulating water. Deionized water was used and the atmosphere above the reaction was inerted with nitrogen. The reactor was charged with 1000 g water, 3 g of sodium bicarbonate and 54.5 g (1.5 ph ) of Rhodacal A246L surfactant (a C ⁇ 2 , ⁇ 4 alpha olefin sodium sulfonate surfactant available from Rhone-Poulenc as a 38.5% solution in water), and heated to 80°C.
• Rhodacal A246L surfactant a C ⁇ 2 , ⁇ 4 alpha olefin sodium sulfonate surfactant available from Rhone-Poulenc as a 38.5% solution in water
• An emulsion was made with 700 g of water, 10.9 g (0.3 phm) of Rhodacal A246L surfactant, 672 g of styrene, 476 g of butyl acrylate, 70 g of 2-hydroxy ethyl methacrylate (HEM A), 140 g of acetoacetoxyethyl methacrylate (AAEM) and 84 g of sodium 2- acrylamido-2-methylpropane sulfonate (AMPS 2405 monomer, available from Lubrizol Corporation as a 50% solution in water).
• HEM A 2-hydroxy ethyl methacrylate
• AAEM acetoacetoxyethyl methacrylate
• AMPS 2405 monomer sodium 2- acrylamido-2-methylpropane sulfonate
• PEI Addition of PEI: A mixture of 336 g of a 40% solution of LUPASOLTM G-35 polyethylenimine (a 50% solids product of BASF) in water, 60 g of Tergitol 15- S-40 surfactant (70% active, Cn - C ⁇ 5 secondary alcohol ethoxylate with an HLB of 18.0, a product of Union Carbide), and 84 g of water was added to the reactor over 30 minutes with a sub-surface feed. The pH of the latex was 11.2 and the particle size was 81 nm.
• LUPASOLTM G-35 polyethylenimine a 50% solids product of BASF
• Tergitol 15- S-40 surfactant 70% active, Cn - C ⁇ 5 secondary alcohol ethoxylate with an HLB of 18.0, a product of Union Carbide
• a latex similar to the one described in Example 1 was prepared with a pH of 7.36, was 42.1% solids and a particle diameter of 74 nm. To 3270 g of this latex was added 330 g of a 40% solution of LUPASOLTM G-35 polyethylenimine (a 50% solids product of BASF) in water. The particle size was 80 nm.
• Example 4 Preparation of a Stable Waterbome Polymer Composition: Latex synthesis: The experimental setup was the same as in Example 1. The reactor was charged with 1100 g water, 9.2 g of sodium bicarbonate and heated to 80°C. A monomer mixture was made with 18 g of Aerosol OT-75 surfactant (a 75% solution of sodium di(2-ethylhexyl)sulfosuccinate in water-alcohol, a product of the Cytec Chemical Co.), 748 g of 2-ethylhexyl acrylate, 100 g of styrene, 187 g of methyl methacrylate, 55 g of acetoacetoxyethyl methacrylate, 1.4 g of trimethylolpropane triacrylate.
• Aerosol OT-75 surfactant a 75% solution of sodium di(2-ethylhexyl)sulfosuccinate in water-alcohol, a product of the Cytec Chemical Co.
• Example 5 Comparative Example: To 150 g of the latex product of Example 4 was added 8.4 g of a 40% solution of LUPASOLTM G-35 polyethylenimine (a 50% solids product of BASF) in water, but without the addition of Tergitol 15 -S-40 surfactant. The mixture partly coagulated as soon as the PEI was added.
• LUPASOLTM G-35 polyethylenimine a 50% solids product of BASF
• a reactor was charged with 358 g of water, 11 g of Maphos 60A surfactant (acid form, 100% active, commercially available from Mazer Chemicals, Inc., Gumee, Illinois) and 5.1 g of 50% sodium hydroxide solution and heated to 80 °C.
• An emulsion was made from 361 g water, 3.3 g of Maphos 60A surfactant (acid form, 100% active, commercially available from Mazer Chemicals, Inc., Gumee, Illinois) and 5.1 g of 50% sodium hydroxide solution and heated to 80 °C.
• An emulsion was made from 361 g water, 3.3 g of Maphos
• 60A surfactant 1.5 g of 50% sodium hydroxide solution, 26.1 g of Tergitol 15- S-40 surfactant (70% active, commercially available from Union Carbide), 31 g of 2-hydroxyethyl methacrylate, 178 g of styrene, 18.4 g of methyl methacrylate, 321 g of butyl acrylate, 49.2 g of acetoacetoxyethyl methacrylate and 36.9 g of sodium 2-acrylamido-2-methylpropane sulfonate (50% solution in water). To the reactor was charged 27 g of this emulsion, followed by a mixture of 1 g of sodium persulfate in 7 g of water.
• the latex was cooled to 30 °C and treated with 0.6 g of Proxel BD20 biocide available from Zeneca Biocides, followed by 200g of LUPASOLTM G- 35 polyethylenimine (40% active; polyethylene imine in water, commercially available from BASF Corporation) and 130 g of 17% ammonium bicarbonate solution.
• the product was a stable waterbome polymer composition having a solids content of 40% and a glass transition temperature (Tg) of 7.5 °C.
• a solution consisting of 256.7 g de- ionized water, 2.0g of surfactant (a 45% solution of Dowfax 2A1, sodium dodecyl diphenyloxide disulfonate available from Dow Chemical), 2.7 g of sodium persulfate, and 3.6 g of sodium bicarbonate.
• An aqueous solution was prepared containing 1.3g of sodium persulfate in 17.6 g of de-ionized water.
• a monomer pre-emulsion was prepared containing 571.3 g of de-ionized water, 29.8g of surfactant (a 45% solution of Dowfax 2A1), 670.7 g of 2-ethylhexyl acrylate, and 223.6 g of ethyl acrylate.
• the reactor charge was heated to 82°C under a nitrogen atmosphere, and
• the product was a latex polymer having a pH of 7.2, a solids content of 50.2%, a particle size of 149 nm, and a glass transition temperature (Tg) of-49.2°C.
• Shear strength is determined in accordance with ASTM D3654-78, PSTC-7 and is a measure of the cohesiveness (internal strength) of an adhesive.
• PSTC designates the Pressure Sensitive Tape Council. It is based on the time required for a static loaded tape sample to separate from a standard flat surface in a direction essentially parallel to the surface to which it has been affixed with a standard pressure. Each test is conducted on an adhesive coated strip applied to a standard stainless steel panel in a manner such that a one-half inch by one-half inch portion of the strip is in firm contact with the panel with one end portion of the strip being free.
• Rolling ball tack is determined in accordance with PSTC-6 and is a measure of the capacity of an adhesive to form a bond with the surface of another material upon brief contact under virtually no pressure.
• Ball Tack test is a method of quantifying the ability of an adhesive to adhere quickly to another surface.
• specimens are cut into 1" x 18" lengths.
• Each specimen is placed onto a rolling ball apparatus (available from Chemsultants International) with adhesive side up.
• a steel ball (7/16 inch diameter) is rolled at a 45 angle onto the adhesive side up specimen. The distance from the point where the ball initially contacts the adhesive to where it stops is measured in inches. The reported values are an average of 5 tests.
• Example 8 Preparation of a Pressure Sensitive Adhesive Composition: Part A: Control
• Example 9 Preparation of a Laminating Adhesive Composition: Part A: Control
• Table 3 Ratio of the Weight of the Polymer Compositions of Examples 6 and 7. Shear Strength, and Bond Strength

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  • 1999-12-20 US US09/467,071 patent/US6649679B1/en not_active Expired - Fee Related
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