Classifications

• • 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
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L93/00—Compositions of natural resins; Compositions of derivatives thereof
  • C08L93/04—Rosin

Definitions

• This invention relates to water-based adhesive coating applications such as for pressure sensitive adhesive compositions and products containing water-based resin emulsions having improved mechanical stability under high shear conditions, and in particular to adhesives based on water-based emulsions of blends of hydrocarbon resins with minor amounts of rosins.
• adhesives It is known that one of the largest uses for hydrocarbon resins is in adhesives. These adhesives are frequently classified by the form in which they are applied to the substrate, ie, solvent, hot-melt or aqueous emulsion. In addition, adhesives are classified by markets, eg, packaging, construction, industrial, pressure-sensitive, transportation, and consumer. Pressure-sensitive adhesives (“PSA”) are typically used in coating applications for or onto any of a number of substrates, and aqueous emulsions are used in many such applications, eg, tapes, labels and films.
• PSA Pressure-sensitive adhesives
• aqueous emulsions containing hydrocarbon resins in coating operations is often characterized by mechanical instability of the emulsion.
• mechanical instability is meant the tendency for the formation of grit or coagulum when the emulsions are submitted to mechanical shear forces. Under the coating condition this leads to deposits at or in critical locations within coating equipment. Excessive formation of the grit or coagulum can cause non-uniform coating and can lead to frequent equipment shut-downs for cleaning.
• Grit or coagulum formation results from the coalescence of emulsified particles when the emulsion is submitted to mechanical shear forces.
• the high shear stress occurring during high-speed coating operations, or during any other processing or handling operations of adhesive systems containing the hydrocarbon resin emulsions, can lead to particle coalescence, and grit or coagulum formation.
• coating of adhesive emulsions can be carried out by several methods.
• the most commonly used methods for coating of pressure-sensitive adhesives are reverse roll and knife-over-roll.
• gravure, wire-wound rod, floating knife, air knife, blade and other methods are also used.
• Several of these methods are known to be high shear methods, see Handbook of Pressure-Sensitive Adhesive Technology, ed. by D. Satas, Ch. 26, pp. 498-532 (Van Nostrand Reinhold Co., 1982).
• the high shear mechanical stability of hydrocarbon resin emulsions has been addressed in EP-A-0 240 253.
• This document describes resin emulsions suitable for PSA in high-speed coating lines to reduce deposits and extended coating times.
• the hydrocarbon resin emulsions are prepared by forming a water-in-oil aqueous emulsion of unsaturated material reactive with the hydrocarbon resin, causing a reaction between the hydrocarbon resin and the reactive material, and adding sufficient water to invert the emulsion to one of reacted hydrocarbon resin in water.
• patent documents address improving the shelf-like stability of hydrocarbon resin or rosin emulsions and/or hydrocarbon resin and rosin mixtures said to be suitable generally for adhesive applications.
• US-A-4 477 613 addresses an aqueous base tackifier of improved shelf stability characterized by the presence of a resinous tackifier composition comprising a carboxyl containing rosin having an acid number value from 30- 150 and containing a counter ion capable of rendering it soluble or dispersible in water, a minor amount of surfactant and a minor amount of an elastomeric latex.
• the resinous tackifier composition is defined as a rosin or rosin derivative, such as on prepared by esterification, having unreacted carboxyl attached.
• the total tackifier solids may be a compatible resinous tackifier selected from low acid value rosin or rosin derivative, hydrocarbon petroleum resins, or polyterpene resins.
• a compatible resinous tackifier selected from low acid value rosin or rosin derivative, hydrocarbon petroleum resins, or polyterpene resins.
• An abstract for JP-A-55- 025 444 addresses aqueous emulsions for paper sizing, paint, ink or adhesive preferably containing 1-50wt.% hydrocarbon resin and 50-99wt.% esterified product of selected rosin plus rosin modified with ⁇ , ⁇ -unsaturated carboxylic acids.
• the hydrocarbon resin is an esterified product of acid-modified petroleum hydrocarbon resin.
• Storage stability is said to be provided resins containing as emulsifier a) a water-soluble polycarboxylic acid, b) a water-soluble salt of a rosin acid, and c) at least one compound of the formula R'(OR") n OH.
• emulsifier a) a water-soluble polycarboxylic acid, b) a water-soluble salt of a rosin acid, and c) at least one compound of the formula R'(OR") n OH.
• United Kingdom patent 1324488 is also concerned with blend of rosins and resins for paper sizing.
• a water-based adhesive of polymer emulsions and a water- based resin emulsion which an emulsified blend of a) hydrocarbon resin and a minor part of b) a rosin, rosin derivative, or blends thereof has improved mechanical stability under high shear conditions.
• the resulting hybrid resin emulsion is exceptionally suitable for use with polymer emulsions in water-based adhesives used in high-speed coating applications where high shear stresses are likely to be developed.
• the hydrocarbon resin used are the known low molecular weight thermoplastic polymers derived from cracked petroleum distillates, turpentine fractions, coal tar, and a variety of pure monomers.
• the number average molecular weight is usually below 2000, and physical forms range from viscous liquids to hard, brittle solids.
• Polymerization feedstreams are derived from the sources described above via various known means and methods of fractionation. Friedel-Crafts polymerization is generally accomplished by use of appropriate catalysts in a polymerization solvent, and removal of solvent and catalyst by washing and distillation. Thermal polymerization is also utilized to some extent, particularly for aliphatic and aliphatic-aromatic petroleum resins.
• the preferred hydrocarbon resins are those known to be useful as tackifiers for adhesive compositions, particularly the petroleum resins derived from the deep cracking of petroleum distillates, hydrocarbon resins from pure aromatic monomers, the coumarone-indene resins from coal tar and the polyterpenes derived from turpentine fractions. Included in petroleum resins are those that have been modified with aromatic or terpene containing feedstreams. For additional description of feedstream derivation, monomer composition, and methods of preparation reference may be made to patent literature (see Background) and to technical literature, eg. Encycl. of Poly. Sci. and Eng'g., vol. 7, pp. 758-782 (John Wiley & Sons, 1987).
• EP-A-O 240 253 its corresponding application U.S. ser. no. 07/065,792, filed 24 June 1987, is incorporated by reference for purposes of U.S. patent practice.
• Hydrogenation is typically accomplished under pressure in the presence of a metal catalyst.
• Acid-modified hydrocarbon resins may be prepared in accordance with the process described in EP-A-O 240 253, or in accordance with the descriptions in the prior art documents listed therein.
• Such hydrogenated and modified hydrocarbon resins, particularly those of the petroleum resins are additionally suitable in accordance with the invention. Additionally, mixtures of any of the foregoing will also be suitable in accordance with the invention.
• Hydrocarbon resin products including unmodified, modified and fully or partially hydrogenated, are widely available.
• Escorez® hydrocarbon resins available through Exxon Chemical Belgium, and Exxon Chemical Co., U.S.A.
• Arkon® hydrocarbon resins available from Arakawa Chemical, Japan
• the Petrosin® hydrocarbon resins available from Toho Petroleum, Japan
• the Zonatac®, Zonarez® hydrocarbon resins available from Arizona Chemical Co., U.S.A
• the Wingtack hydrocarbon resins available from Goodyear Chemicals, U.S.A
• Eastotac hydrocarbon resins available from Eastman Ko
• Particularly preferred petroleum hydrocarbon resins for use in this invention will include those described in EP-A-O 196 844, specifically those having a softening point from 10°C to 120°C and being copolymer of a feed comprising C5 olefins and diolefins and from 10 to 60 wt. % monovinylaromatic compound.
• the rosin used include any of those known in the art to be suitable as tackifying agents, and includes preferably those that have been modified by hydrogenation,
• the modified rosins and rosin derivatives are preferred.
• the rosin acids are particulary suitable for compositions of the invention. Mixtures of any of the foregoing will also be suitable.
• the principal sources of the rosin include gum rosin, wood rosin, and tall oil rosins which typically have been extracted or collected from their known sources and fractionated to varying degrees. Additional background can be obtained from technical literature, e.g., Kirk-Othmer Encycl. of Chem. Tech., vol. 17, pp.
• Rosin and rosin derivative products suitable in accordance with the invention are available commercially, for example, Foral®, Pentalyn®, and Staybelite® of Hercules, Inc., U.S.; and Sylvatac® of Sylvachem Corp., U. S.; Bevitack®, Bevilite®, Bevipale® of Bergvick Kemi AB, Arizona Chem.
• rosin component 50 wt.% or less of the total hybrid resin is the rosin component, in other words, the hydrocarbon resin represents 50 wt.% or more of the total resin components.
• As little as 15 wt.% rosin component results in significant improvement in the mechanical stability of resins prepared with suitable emulsifiers, see below, some noticeable improvement results from inclusion of even less.
• more rosin component than hydrocarbon resin component can be effectively used, it is no longer properly termed a "hydrocarbon resin emulsion", and takes on properties more close to those of a rosin emulsion.
• the rosin component will preferably constitute 10 up to 50 wt.% or less, and more preferably 10-45 wt.%, most preferably 10-25 wt.%.
• the method of preparation of the hybrid resin emulsion of the invention in its broadest terms includes the steps of blending the a) hydrocarbon resin and a minor part of the b) rosin or rosin derivative and emulsifying the resulting blend.
• the hydrocarbon resin and rosin components are melt-blended so as to achieve an intimate blend and are then emulsified in any manner suitable for preparing aqueous emulsions or dispersions.
• the emulsification process will be by direct emulsification or inverse emulsification, by either of batch or continuous processes.
• a preferred continuous, direct emulsification process comprising the use of static mixers is described in EP-A-O 283 247, and its corresponding application U.S.
• the preferred blending comprises blending the hydrocarbon resin and rosin components by any physical means, typically in a heated, stirred vessel.
• the resin and rosin components of the invention should preferably be molten or liquid under the blending conditions employed. Alternatively, softening to a point that the components are effectively blended is sufficient. In many cases the hydrocarbon resin or rosin component of higher softening or melting point will be at least partly soluble in the lower softening or melting point component, or one or the other, or both, will be liquid, any of which permits of the intimate blending preferred.
• Temperatures necessary to achieve appropriate softening or solubilising of the components are achieved by the energy of mixing and/or by heating. The necessary temperatures depend upon the softening points of the components and can be determined empirically within ordinary polymer engineering practices.
• the emulsification process step will include providing a surfactant as emulsifier.
• a surfactant as emulsifier.
• Any of the known emulsifier compositions suitable for rosin emulsions are suitable in accordance with the invention, but most preferably the anionic or non-ionic surfactants are used.
• Preferred examples of the anionic surfactants include those derived from polyoxyethylene, like alkyl- or alkylaryloxy-poly(ethyleneoxy)-ethanol-sulfates, sulfonates, sulfosuccinates and phosphates.
• Preferred non-ionic -surfactants are those derived from polyoxyethylene like alkyl- or alkylaryloxy-poly(ethyleneoxy)-ethanol.
• the amount of emulsifier used will be from 2-10 pbw per 100 parts hydrocarbon resin, more typically 4-7 pbw. Additionally, it was observed in the preparation of the examples that follow, that increasing the length of the hydrophilic polyethylene oxide chain of the preferred surfactants further improved the mechanical stability. Likely this occurs from increasing the steric barrier to particle coalescence. It is believed that the inclusion of the rosin component with the hydrocarbon resin compound increases the polarity of the emulsified material, and the energy needed to overcome the repulsion between the dispersed phase particles. As a result coalescence in a significant degree is avoided, even under higher stress conditions previously thought impractical for hydrocarbon resin emulsions.
• the high speed coating operations used for PSA compositions can achieve roll-speeds of up to about 300 m/min, have a tolerance between roller and blade of 10-40 micron(micrometer) and accordingly exhibit a shear rate on the order of approximately 10 5 sec 1 .
• petroleum resins can be used in such operations without the previously observed formation of significant coagulum or grit.
• the adhesives are water-based PSA compositions that are applied by a high speed coating process to a typical substrate such as thermoplastic film, siliconized paper for transfer coating for the production of tapes, labels and the like.
• the polymer emulsion that is blended with the hybrid emulsion of the invention are any of those known for PSA applications and will include those based on polyacrylics (particularly the rubbery polyacrylates) and modified polyacrylics ; natural rubber and blends thereof with synthetic elastomers ; styrene block polymers ; styrene-butadiene rubber and carboxylated derivatives ; and butyl rubber (including modified butyl copolymers containing ⁇ -methyl or p-methyl styrene, halogenated butyl and modified butyl polymers, polyisobutylene, and mixes).
• Typical wt.% of polymer emulsion component in PSA is 50-90, based on total dry weight of the PSA composition.
• hydrocarbon resins were made by the Friedel-Crafts copolymerization of C5 olefins and C5 diolefins petroleum feedstocks with styrene according to EP-A-O 196 844 and its corresponding U.S. ser. no. 07/058,652, incorporated by reference above.
• the hydrocarbon resins were blended with rosins and the blends then emulsified via an inverse emulsification process as described in US-A-4 414 346.
• the blending step involved the melting and the blending of the hydrocarbon resin with the rosin(s) in a stirred reactor within a temperature range of 80°C to 95°C, prior to the surfactant addition and the inverse emulsification stage.
• the resulting emulsions were characterized for particle size with a Coulter N4 Submicron Particle Size Analyzer (results in nanometers, "nm").
• the mechanical stability of the resulting hydrocarbon resin emulsion was evaluated by blending the hydrocarbon resin emulsion with an acrylic emulsion, and submitting the blend to mechanical shear forces. Comparison with the mechanical stability of commercially available rosin emulsions (currently used in high speed coating applications) in the same test is provided.
• the resin emulsion was mixed with NeoTac® 576 (acrylic emulsion of ICI Resins Ltd., U.K., having a solids content of 63 wt %) and diluted with deionized water such as to result in an emulsion blend characterized by a resin/acrylic dry weight ratio of 20 / 80 and a total solids content of 56 wt %.
• the resin emulsion was mixed with the same acrylic emulsion as in test A such as to result in a hydrocarbon resin/acrylic dry weight ratio of 30 / 70 and a total solids content of 56 wt %.
• 150 gr of the emulsion blend was placed in a cylindrical flask with a few drops of defoamer (Drewplus® 4510, Drew Ameroid N.V., Belgium).
• the mixture was sheared with a Ultraturrax T 25 rotor stator for 5 minutes at 8000 RPM while the temperature was maintained at 22 °C.
• the coagulum formed in the test was collected and dried. The amount formed is reported in the tables below as wt % of the total solids of the emulsions.
• Atlox® 3404FB alkyl benzene sulfonate and non ionic surfactant blend provided by ICI
• Antarox® CO 433 sodium salt of nonlyphenoxy (polyethyleneoxy) ethanol sulfate having 4 methylene oxide units
• Hybrid emulsion resin composition Mechanical Stability (w t %) (wt % coagulum)
• PE was untreated polyethylene cast film (ESCORENE® LD 151, Exxon Chemical Co., U.S.A.), 200 micron (micrometer)

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• 1993
  • 1993-04-16 GB GB939307908A patent/GB9307908D0/en active Pending
• 1994
  • 1994-04-14 WO PCT/IB1994/000177 patent/WO1994024221A2/en not_active Application Discontinuation
  • 1994-04-14 KR KR1019950704495A patent/KR960701967A/ko not_active Application Discontinuation
  • 1994-04-14 JP JP6522955A patent/JPH08509007A/ja active Pending
  • 1994-04-14 EP EP94917773A patent/EP0694055A1/de active Pending

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