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
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/10—Adhesives in the form of films or foils without carriers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
• • 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
  • C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
  • C09J123/02—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
  • C09J123/10—Homopolymers or copolymers of propene
  • C09J123/14—Copolymers of propene
• • 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
  • C09J157/00—Adhesives based on unspecified polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/01—Hydrocarbons

Definitions

• the present invention relates to pressure sensitive hot melt adhesive compositions that comprise a metallocene-catalyzed polyolefin random copolymer. Crystallization in the adhesives are inhibited over time and the adhesives maintain a balance of peel and tack performances, making these adhesives particularly well suited for electronics, medical, industrial, graphics, construction and consumer goods
• Pressure sensitive adhesive is aggressive, permanent tacky, adheres to a substrate with finger or hand pressure, and exerts a strong holding force to the substrate.
• the pressure sensitive adhesives do not require any solvent, water, or heat to activate the adhesives.
• Pressure sensitive adhesives form bonds by balancing flow and resistance to flow: the adhesives are soft enough to flow and wet the substrate, and the bond has strength because the adhesives are hard enough to resist flow when stress is applied to the bond.
• Pressure sensitive hot melt adhesives are applied to a substrate while in a molten state and cooled to harden the pressure sensitive adhesive layer.
• Such adhesives are widely used for various commercial and industrial applications such as film, label, packing slip, pouch, security bag, tape, graphic art, positioning adhesive, medical dressing, personal care product, hygienic applications, feminine care product, and the like.
• Typical pressure sensitive hot melt adhesive is formed from an elastomeric base polymer.
• Widely selected elastomeric base materials include natural rubber, vinyl ethers, acrylics, butyl rubber, styrene block copolymers, silicones and nitriles.
• Rubber-based PSHMA adheres well to various substrates, but tends to yellow over time and is not recommended for high heat application.
• PSHMA formed with acrylic polymers generally has a better long term aging performances, but has poor adhesion to low-surface energy substrates.
• Silicone-based PSHMA also suffers from poor adhesion to low surface energy substrates.
• amorphous poly-alpha-olefins in the adhesive tend to build crystallinity over time, thereby losing tack.
• Pressure-Sensitive Adhesive and Applications 2 nd Ed., Istvan Benedek, CRC Press, 2004, pp 144-145, teaches that adhesives made with amorphous poly-a!pha-olefins exhibit initial pressure sensitive adhesive properties due to long open time; however, afterwards the adhesives are no longer tacky.
• Patent Number 7,199, 80 teaches that pressure sensitive adhesives can be formed with low molecular weight (weight average molecular weight, Mw, of less than 100,000) metallocene catalyzed ethylene/alpha-olefin polymers; however, it is silent as to the adhesives 1 ability to maintain pressure sensitivity over a prolonged time.
• Mw weight average molecular weight
• OBC olefin block copolymer
• the invention provides polyolefin based pressure sensitive hot melt
• the present invention provides polyolefin based pressure sensitive hot melt adhesives and articles of manufacture comprising the polyolefin based pressure sensitive hot melt adhesives.
• One aspect of the invention is directed to pressure sensitive hot melt adhesives comprising greater than about 15 weight percent of a metallocene-catalyzed polyolefin random copolymer.
• the adhesives have (i) a heat of fusion less than 1.5 J/g, measured at c/min heating and cooling rate in accordance with ASTM D3418-12, and (ii) a glass transition temperature (Tg) from -40°C to 5°C.
• Another aspect of the invention is directed to a hot melt pressure sensitive adhesives comprising (a) about 0 to about 40 wt% of a metallocene-catalyzed polyolefin random copolymer that has a heat of fusion less than about 15 J/g measured at 10°C/min heating and cooling rate in accordance with ASTM D3418-12; (b) about 40 to about 85 wt% of a tackifier; (c) about 1 to about 50 wt% of a plasticizer; and (d) optionally, an additive.
• the pressure sensitive adhesives have (i) a heat of fusion less than 1.5 J/g, measured at 1 °C/min heating and cooling rate in accordance with ASTM D3418-12; (ii) a glass transition temperature (Tg) from -40°C to 5°C; and (iii) a storage modulus (C), at 25°C, of less than 5 ⁇ 10 4 Pascal.
• Yet another aspect of the inventions directed hot melt pressure sensitive adhesives comprising greater than 15 wt% of a polyolefin polymer; wherein the adhesives have (i) a heat of fusion less than 1.5 J/g measured at 1 °C/min heating and cooling rate in accordance with ASTM D3418-12; (ii) a glass transition temperature (Tg) from -40°C to 5°C; (iii) a peel force of at least 150 gf/in on a cotton fabric substrate in accordance with cotton peel method at 25 gsm add-on level; and (iv) an aged peel force after 10 weeks at 40°C of at least 00 gf/in on a cotton fabric substrate in accordance with cotton peel method at 25 gsm add-on level.
• PSA pressure sensitive adhesive
• PSHMA pressure sensitive hot melt adhesive
• polymer as used above includes homopolymers and copolymers such as terpolymers, tetrapolymers, and etc.
• the PSHMA of the invention comprises a polyolefin random copolymer, which has a heat of fusion less than 15 J/g, measured at 10°C/min heating and cooling rate in accordance with ASTM D3418- 2.
• the PSHMA comprise greater than about 15wt% of the polyolefin random copolymer.
• the polyolefin random copolymer is a metallocene-catalyzed polyolefin random copolymer. This copolymer is randomly ordered, without any specific order to the polymer structure.
• the copolymer is described as having semi-crystalline structure, and specifically contains low crystallinity in the copolymer.
• the term "semi-crystalline" used for the olefinic polymer refers to those polymeric materials that contain both crystalline and amorphous regions in the solid state.
• the molecular chains of the polymers are all arranged in ordered three-dimensional arrays whose structure can be fully characterized by their unit cells, the smallest structural unit used to describe a crystal.
• the amorphous polymers in contrast, do not have ordered three-dimensional structures in the solid state. Their molecular chains are arranged in a completely random fashion in space.
• Semi-crystalline polymers can be easily distinguished from completely amorphous polymers by observing the presence or absence of a melting point (Tm) and the associated enthalpy or heat of fusion (AHf) derived from the transformation of the crystalline state to molten state upon heating. All semi-crystalline polymers exhibit a melting point, whereas the melting point is absent for amorphous polymers. Amorphous polymers undergo a transition from a glassy solid to a rubbery elastic state in a narrow temperature range around a glass transition temperature Tg. One should not confuse the glass transition temperature Tg with the melting point Tm.
• Tm melting point
• AHf heat of fusion
• the melting point Tm, the enthalpy or fusion (AHf) can be determined by Differential Scanning Calorimetry (DSC). The technique is well known to those skilled in the art and is well described in scientific literature.
• the metallocene-catalyzed polyolefin random copolymer has a heat of fusion value of less than 30 J/g, more preferably less than 20 J/g, and most preferably less than 15 J/g, measured at 10°C/min heating and cooling rate in accordance with ASTM D3418-2.
• the weight average molecular weight (Mw) of the polyolefin random copolymer is greater than 100,000, preferably greater than 100,100, more preferably greater than 100,500, and most preferably, greater than 101 ,000 Daltons.
• Mw weight average molecular weight
• the use of polyolefin random copolymers with Mw less than 100,000 is not preferred because adhesives made from such copolymers have low cohesive strength and thus, result in low shear strength.
• the metallocene-catalyzed polyolefin random copolymers of the type described above can be purchased from numerous commercial sources, such as Exxon Mobil Chemical under the trade name Vistamaxx.
• the PSHMA further comprises another polymer, in an amount less than 10 wt%.
• the PSHMA is essentially free of other polymers that have a heat of fusion less than 15J/g.
• the PSHMA is essentially free of any other polymers other than the metallocene-catalyzed polyolefin random copolymers with a AHf below 15J/g.
• other polymers e.g., styrene block polymers, olefin block copolymer (chain shuttling technology), and amorphous poly-alpha-olefin polymer, lead to undesirable adhesive performance, such as decreased tack and peel
• the PSHMA further comprises a tackifier.
• tackifier refers to one or more compounds that are useful to impart tack to the adhesive of the present invention.
• suitable tackifiers include, but are not limited to, aliphatic hydrocarbon resins, aromatic modified aliphatic hydrocarbon resins,
• polycyclopentadiene resins hydrogenated polycyclopentadiene resins, polycyclopentadiene resins, gum rosins, gum rosin esters, wood rosins, wood rosin esters, tall oil rosins, tall oil rosin esters, polyterpenes, aromatic modified polyterpenes, terpene phenolics, aromatic modified hydrogenated polycyclopentadiene resins, hydrogenated aliphatic resin, hydrogenated aliphatic aromatic resins, hydrogenated terpenes and modified terpenes, hydrogenated rosin acids, and hydrogenated rosin esters.
• the tackifier is hydrogenated.
• the tackifier is non-polar, which indicates that the tackifier is substantially free of monomers having polar groups.
• the polar groups are not present, however if they are preferably they are not present at more that 15 wt%, preferably not more that 10 wt%, even more preferably no more than 5 wt%.
• the tackifier has a softening point (Ring and Ball, as measured by ASTM E-28) of 80°C to 150°C, preferably 100°C to 130°C.
• the resin is a liquid and has a Ring and Ball softening point of between 10 and 80°C.
• Preferred hydrocarbon resins for use as tackifiers or modifiers include:
• Resins such as C5/C6 terpene resins, styrene terpenes, alpha-methyl
• styrene terpene resins C9 terpene resins, aromatic modified C5/C6, aromatic modified cyclic resins, aromatic modified dicyclopentadiene based resins or mixtures thereof.
• these resins are obtained from the cationic polymerization of compositions containing one or more of the following monomers: C5 diolefins (such as 1 -3 pentadiene, isoprene, etc); C5 olefins (such as 2-methylbutenes, cyclopentene, etc.); C6 olefins (such as hexene) , C9 vinylaromatics (such as styrene, alpha methyl styrene, vinyltoluene, indene, methyl indene, etc.); cyclics (such as
• dicyclopentadiene methyldicyclopentadiene, etc.
• terpenes such as limonene, carene, etc.
• vinylaromatics such as styrene, alpha-methyl styrene, vinyl toluene, indene, methyl indene.
• the resins obtained after polymerization and separation of unreacted materials can be hydrogenated if desired.
• the tackifier is typically present at about 40 to about 85 wt%, based upon the total weight of the adhesive, and more preferably at about 45 to about 80 wt%.
• Preferred plasticizers include oils, polybutenes, phthalates benzoates, adipic esters and the like.
• Suitable oils include mineral oil, aliphatic oils, aromatic oils, olefin oligomers and low molecular weight polymers, as well as vegetable and animal oils and derivatives of such oils.
• the petroleum derived oils which may be employed are relatively high boiling materials containing only a minor proportion of aromatic hydrocarbons. In this regard, the aromatic hydrocarbons should preferably be less than 30% and more particularly less than 15% of the oil, as measured by the fraction of aromatic carbon atoms.
• the oligmers may be polypropylenes, polybutenes,
• Suitable vegetable and animal oils include glycerol esters of the usual fatty acids and polymerization products thereof. Particularly preferred oils include aliphatic naphthenic oils.
• Plasticizer is typically present at about 1 to about 50 wt%, based upon the total weight of the adhesive, more preferably 10 to 40 wt%.
• the combination of the metallocene-catalyzed polyolefin random copolymer that has a ⁇ less than 15 J/g, tackifier and plasticizer inhibits the crystallization in the adhesive to maintain pressure sensitivity of the adhesive. Peel and tack performances of the PSHMA of the invention is balanced even after the adhesive is aged for 10, and even up to 16 weeks.
• the PSHMA optionally comprises additives known in the art such as stabilizers, antioxidants, fillers, additives, pigments, dyestuffs, polymeric additives, defoamers, preservatives, thickeners, rheology modifiers, humectants, masterbatches, waxes, nucleating agent, block, antiblock, processing aids, UV stabilizers, neutralizers, lubricants, surfactants and adhesion promoters.
• additives known in the art such as stabilizers, antioxidants, fillers, additives, pigments, dyestuffs, polymeric additives, defoamers, preservatives, thickeners, rheology modifiers, humectants, masterbatches, waxes, nucleating agent, block, antiblock, processing aids, UV stabilizers, neutralizers, lubricants, surfactants and adhesion promoters.
• Preferred antioxidants include thioesters, phosphates, hindered phenols, tetrakis (methylene 3-(3',5'-di-t-butyl-4 hydroxyphenyl)pro-pionate)methane, 2,2'- ethyldenebis (4,6-di-tertiarybutylphenol), 1 ,1-3-tris(2-methyl-4-hydroxy-5-t-butylephenyl) butane, 1 ,3,5-trimethyl2,4,6,tris(3,5-tertbutyl-4-hydroxybenzyl)benzene,
• dilaurylthiodipropionate pentaerythritol tetrakis(beta-laurylthiopropionate), alkyl-aryldi- and polyphosphates, thiophosphites, and combinations or derivatives thereof.
• Preferred fillers include titanium dioxide, calcium carbonate, barium sulfate, silica, silicon dioxide, carbon black, sand, glass beads, mineral aggregates, talc, clay, calcium sulfate, calcium metasilicate, aluminium silicates, china clay, kaolin, glimmer, Mg- and Al-oxides and hydroxides glass fibers, synthetic fibers,
• Preferred additives include silicon dioxide, titanium dioxide, and
• polydimethylsiloxane polydimethylsiloxane, talc, dyes, calcium sterate, carbon black, low molecular weight resins and glass beads.
• Preferred adhesion promoters include polar acids,
• polyaminoamides such as Versamid 1 15, 125, 140, available from Henkel
• urethanes such as isocyanate/hydroxy terminated polyester systems, e.g. bonding agent
• TN/Mondur Cb-75 (Miles, Inc.), coupling agents, (such as silane esters (Z-6020 from Dow Corning)), titanate esters (such as Kr-44 available from Kenrich), reactive acrylate monomers (such as sarbox SB-600 from Sartomer), metal acid salts (such as Saret 633 from Sartomer), polyphenylene oxide, oxidized polyolefins, acid modified polyolefins, and anhydride modified polyolefins.
• coupling agents such as silane esters (Z-6020 from Dow Corning)), titanate esters (such as Kr-44 available from Kenrich), reactive acrylate monomers (such as sarbox SB-600 from Sartomer), metal acid salts (such as Saret 633 from Sartomer), polyphenylene oxide, oxidized polyolefins, acid modified polyolefins, and anhydride modified polyolefins.
• the adhesive composition is prepared by standard melt blending procedures. Any mixing method producing a homogeneous blend without degrading the components is satisfactory.
• the mixing temperatures depend upon the particular adhesive formulation, and are generally in the range of about 130°C to about 200°C, with about 135°C to about 175°C being a typical suitable range.
• the prepared PSHMA is permanently tacky in dry form and can firmly adhere to a substrate with very light pressure.
• An adhesive is considered to be a PSA if it is sufficiently soft and meets the Dahlquist criterion by exhibiting an elastic modulus of less than 3 X 10 5 Pascal (3 X 10 6 dyn/cm 2 ) on a 1-s time scale at the test temperature.
• adhesive deformation can be described by storage modulus (G') and loss modulus (G").
• Storage modulus is the energy stored by the adhesive is directly related to elasticity.
• Adhesives with high modulus (higher than the Dahlquist criterion) in the rubbery plateau region are not tacky and do not have PSA properties.
• the PSHMA of the invention has a storage modulus value of less than 5 X 10 4 Pascal at 25°C.
• the tan(6) value is expressed as G7G 1 and this is a function of temperature, and such measurements are well known to those skilled in the art. It is also well understood in the art that the temperature at the peak of tan(6) is determined to be a representation of the glass transition temperature (Tg) of the adhesive. For a PSA, the peak Tg should be well below the room temperature to allow the adhesive to be tacky and usable at ambient temperatures.
• Tg glass transition temperature
• the PSHMA of the invention has a peak Tg in the range of -40°C to 5°C.
• the PSHMA of the invention has a heat of fusion less than 1.5 J/g measured at 1 °C/min heating and cooling rate in accordance with ASTM D3418-12. Even after aging the PSHMA for a prolong time, the heat of fusion does not significantly change as crystallization in the adhesive is inhibited over time.
• the PSHMA of the invention maintains a balance of peel and tack performances for a prolonged time under aging conditions.
• the adhesive compositions of this invention can be used in any PSA application, including but not limited to films, labels, packing slips, pouches, security bags, tapes, graphic arts, positioning adhesives, medical dressings, personal care products, hygienic applications, feminine care products, and the like.
• PSA application including but not limited to films, labels, packing slips, pouches, security bags, tapes, graphic arts, positioning adhesives, medical dressings, personal care products, hygienic applications, feminine care products, and the like.
• the PSHMA is applied onto polyethylene and/or polypropylene film as a positioning/garment attachment adhesive for feminine care products.
• the PSHMA of the invention has affinity to multiple fabric substrates, including microfiber, cotton, nylon, and the like.
• the adhesive compositions described above may be applied to a variety of substrate, including substrates with high or low surface energies.
• the adhesive compositions of the present invention adhere and maintain a balance of peel and tack to both low and high surface energy substrates.
• One set of preferred substrates include polyethylene, polypropylene, polyacrylates, acrylics, polyethylene terephthalate, or any of the polymers listed above as suitable for blends and their composites with fillers, glass fibers and the like.
• Another set of substrates include wood, such as such as particle board, wood-plastic- composites, veneer paper, paper based materials such as melamine impregnated papers, cardboard, plastic, thermoplastic, rubber, metal, metal foil, metallized surfaces, cloth, nonwovens, spunbonded fibers, cardboard, stone, plaster, glass, foam, rock, ceramics, films, polymer foams, substrates coated with inks, dyes, pigments, PVDC and the like or combinations thereof.
• Preferred substrates can also be selected from the group of biodegradable films, such as biodegradable films comprising natural or synthetic materials. Any of the above substrates, and/or the polymers of this invention, may be corona discharge treated, flame treated, electron beam irradiated, gamma irradiated, microwaved, plasma treated, or silanized.
• the adhesive composition can be applied at a molten state onto the above said substrates by any application procedures, including but not limited to application with rollers, nozzles, spraying units, slot die and the like.
• the adhesives can be applied partially or fully onto one or multiple substrates to form a bond.
• the PSHMA is applied onto the substrate of the article at a molten state and the adhesive is cooled.
• the PSHMA can be attached and reattached onto a second substrate with pressure, and maintains tack and peel over prolonged time.
• Typical thickness of the PSHMA is applied from about 0.2 to about 5 mil thickness onto a substrate.
• a liner or a second substrate is applied on top of the applied adhesive, or the adhesive is wound in a roll.
• the adhesives of the invention balances tack and peel performances to be useful as PSHMA.
• the adhesives have (i) a heat of fusion less than 1.5 J/g, measured at 1 °C/min heating and cooling rate in accordance with ASTM
• the adhesives further have a peel force on of at least 150 gf/in on a cotton fabric substrate in accordance with cotton peel method at 25 gsm add-on level, and maintain this strength even after aging for 10 weeks at 40°C.
• the adhesives have a peel force of at least 5 lb/in (80 oz in) on a stainless steel testing panel, in accordance with PSTC-101 at 25 gsm add-on level; and maintain this peel strength even after aging for 16 weeks at ambient.
• Heat of fusion was measured by at a rate of 10°C/min for polymer, and 1 °C/min for adhesive, heating and cooling in accordance with ASTM D3418-12.
• the storage modulus (G') at 20°C was measured by rheology techniques on a Rheometric RDA-III Dynamic Analyzer.
• the Temperature-Step mode was used utilizing the 8 mm diameter parallel plate geometry.
• the sweep run was attained from about -50°C to 150°C at 5°C per step with 10 seconds equilibration delay at each step.
• the oscillatory frequency was 10 radians/second with an autostrain function of 0.05 percent strain initially, increasing in positive 30% percent adjacent whenever the torque decreased to 200 gram-centimeters.
• the maximum strain was set at 30%.
• the plates were used with an initial gap of 2.5 mm.
• the sample was loaded at 90°C, and then cooled to -50°C, and the test started (the "hold") function corrected for the thermal expansion or contraction of the test chamber is heated or cooled.
• the sample was maintained in a nitrogen environment throughout the measurement.
• the peak tan delta (a representation of the glass transition temperature) was determined from the above rheology measurements, and specifically from the peak value from a plot of G7G' against temperature.
• Tack or adhesion refers to the adhesive's ability to bond immediately to a surface. Tack was determined by loop tack measurement, method PSTC-16.
• Peel value quantifies the strength of the adhesion of the adhesive to the substrates. Peel values of the adhesive was measured on stainless steel substrate and cotton substrates for both initial and aged samples. For peel values measured on stainless steel substrate, method PSTC-101 was followed. For peel values measured on cotton substrates, the cotton peel method was as follows:
• the adhesive was applied molten via slot coating to a release liner and transfer coated to a polyethylene film.
• the adhesive pattern was approximately 1.5 inches wide and a coat weight of 20 gsm.
• Adhesive samples with various base polymers were made, in accordance with Table 1.
• the adhesives were formed by mixing the base polymer with a
• hydrocarbon tackifier having a R&B softening point of about 100°C
• plasticizer liquid at room temperature
• PSA-3 used different hydrocarbon tackifiers and plasticizers than PSA-1.
• Comparative Sample A was prepared in accordance with US 201 /0021 03, example 17121-42-J-C.
• the polymer blend of OBC and APAO resulted in a peak Tg values too high to be useful as a PSA.
• Comparative Sample B containing a
• Comparative Sample C DISPOMELT® LITE 300 (APAO based) is a
• Comparative Sample C lost pressure sensitivity within three days of aging at 40°C. Comparative Sample D, also APAO based, lost pressure sensitivity upon aging.
• Samples PSA-1 and PSA-2 resulted in acceptable PSA properties: heat of fusion less than 1.5 J/g and a peak Tg value of 0°C.
• Sample PSA-3 contains a mixture of metal!ocene-catalyzed polyolefin random copolymers having different Mw.
• the adhesive made with the mixture of metallocene catalyzed polyolefin random copolymers had acceptable PSA properties: heat of fusion less than 1 .5 J/g and a peak Tg value of - 4 D C.
• Sample PSA-1 was formed with the components shown in Table 2. Table 2.
• Sample PSA-1 had a heat of fusion value of 0.580 J/g, Tg peak value of 0°C, a storage modulus (G') at 25°C of 3 x 10 4 , and a loop tack value of 7.6 lbs.
• Sample PSA-1 exhibited excellent initial peel strength to stainless steel substrate, and maintained this performance even after 16 weeks of aging. In contrast, the peel strength of Comparative Sample B had lower initial peel strength value and this decreased over time.
• Sample PSA-2 exhibited excellent cotton peel performance and had minimal change in performance even after aging 10 weeks at 40°C. Comparative Sample D, APAO-based, had significantly lower initial peel strength than Sample PSA-3, and this value decreased over time, and became immeasurable after 10 weeks. While not bound to any specific theory, it is believed that the APAO base polymer increased crystallization over time, and thus, the tack and peel performances decreased.

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• Chemical Kinetics & Catalysis (AREA)
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• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Adhesives Or Adhesive Processes (AREA)

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• 2014
  • 2014-06-20 CN CN201480034831.9A patent/CN105324451A/zh active Pending
  • 2014-06-20 EP EP14813856.3A patent/EP3010990A4/en not_active Withdrawn
  • 2014-06-20 WO PCT/US2014/043389 patent/WO2014205336A2/en not_active Ceased
  • 2014-06-20 JP JP2016521838A patent/JP2016528323A/ja active Pending
  • 2014-06-20 BR BR112015031395A patent/BR112015031395A2/pt not_active Application Discontinuation
• 2015
  • 2015-12-17 US US14/972,971 patent/US20160102228A1/en not_active Abandoned

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