Classifications

• • 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
  • C08K5/0083—Nucleating agents promoting the crystallisation of the polymer matrix
• • 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
  • C08K5/04—Oxygen-containing compounds
  • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
  • C08K5/098—Metal salts of carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/10—Homopolymers or copolymers of propene
  • C08L23/14—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
  • 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
• • 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
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/10—Homopolymers or copolymers of propene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/10—Homopolymers or copolymers of propene
  • C08L23/14—Copolymers of propene
  • C08L23/142—Copolymers of propene at least partially crystalline copolymers of propene with other olefins

Definitions

• the invention relates to a polyolefin adhesive composition that comprises one or more nucleating agents for improving the set time of the finished adhesive.
• packaging grade hot melt adhesive (“HMA”) formulations include a base polymer, and one or more waxes and tackifiers.
• HMA hot melt adhesive
• the set-time of the HMA is a key parameter for packaging grade HMAs. This is because lower set times enable faster packaging line speeds.
• Set-time is the minimum time interval, after bonding of two substrates, during which the cohesive strength of the bond becomes stronger than the joint stress (often called the pop open force). Set-time thus represents the time necessary to cool down the HMA and obtain a good bond.
• Open-time is the maximum time interval, after application of the liquid HMA, during which a second substrate can be brought into contact with the molten adhesive and a good bond will be formed. Generally, once the adhesive has cooled to a certain temperature, it is no longer possible to make a bond.
• HMA formulators attempt to design HMA formulations that have long open time and short setting times, a balance which is difficult to achieve.
• an adhesive composition comprising a polyolefin composition comprising a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C 10 alpha-olefin, and a nucleating agent effective for decreasing the set time for the adhesive composition in comparison to an otherwise identical adhesive composition in which the nucleating agent is absent.
• the nucleating agent may be an organic metal salt.
• the adhesive composition has a Dot T-Peel of 1 Newton or more on Kraft paper.
• an adhesive composition comprising a polyolefin composition comprising a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C alpha-olefin, and a nucleating agent effective for decreasing the set time for the adhesive composition in comparison to an otherwise identical adhesive composition in which the nucleating agent is absent, wherein the nucleating agent is an inorganic solid particle or an organic component having a crystallization temperature greater than that of the polyolefin composition.
• the adhesive composition has a Dot T-Peel of 1 Newton or more on Kraft paper.
• an adhesive composition comprising a polyolefin composition comprising a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C 10 alpha-olefin; and a nucleating agent effective for decreasing the set time for the adhesive composition by at least 10% in comparison to an otherwise identical adhesive composition in which the nucleating agent is absent.
• the adhesive composition has a Dot T-Peel of 1 Newton or more on Kraft paper.
• FIG. 1 is a graphical depiction illustrating various adhesive compositions building strength over time.
• FIG. 2 is a graphical depiction illustrating a differential scanning calorimetry cooling curve for Composition F of Table 1.
• FIG. 3 is a graphical depiction illustrating a differential scanning calorimetry cooling curve for Composition F of Table 1.
• Adhesive formulations are disclosed herein that enable enhanced adhesive properties and deliver excellent set-times while maintaining long open times.
• the formulations enable the usage of higher polymer loads in the finished adhesive, thereby delivering enhanced adhesive strength.
• the formulations may reduce adhesive density and provide a pathway for reducing the mass and volume of adhesive that must be applied on packaging lines. By lowering adhesive volumes, set time may be further improved due to the fact that the reduced thermal mass requires less time to cool.
• the formulations disclosed herein may deliver improved set times while maintaining long open times by the incorporation of nucleating agents in the adhesive formulation.
• the formulation may include a polyolefin composition comprising a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to Cio alpha-olefin.
• the polyolefin composition may comprise a copolymer of propylene and ethylene.
• the nucleating agent may be effective for decreasing the set time for the adhesive composition, preferably by at least 10%, in comparison to an otherwise identical adhesive composition in which the nucleating agent is absent. In any embodiment, the nucleating agent may be effective to increase the onset crystallization temperature of the polyolefin composition relative to the adhesive composition in which the nucleating agent is absent. In any embodiment, the nucleating agent may be effective to increase the onset crystallization temperature of the polyolefin composition by at least 10°C relative to the adhesive composition in which the nucleating agent is absent.
• the nucleating agent may be a metal salt.
• the nucleating agent may be an organic compound having a crystallization temperature greater than the crystallization temperature of the polyolefin composition.
• the nucleating agent may be selected from the group consisting of sodium benzoate, talc, glycerol alkoxide salts, cyclic carboxylic acid salts, bicyclic carboxylic acid salts, glycerolates, and hexahydrophtalic acid salts.
• the nucleating agent comprises a salt of bicyclo [2.2.1] heptane dicarboxylate.
• the improvement in set-time enabled by the formulations disclosed herein may be achieved using reduced amounts of wax, or more preferably little to no wax.
• the adhesive composition may comprise about 25 wt% wax or less, or about 5 wt% wax or less, or substantially no wax.
• the formulations disclosed herein are broadly applicable to multi-modal polymer blends that have a combination of properties that are beneficial for use in adhesive compositions.
• the nucleating agents may be employed with polyolefin compositions having multi-modal polymer blends in which the blend includes at least two polymers having a difference of heat of fusion of about 20 J/g or more, or about 30 J/g or more.
• the nucleating agent may be employed to reduce the set time of a multimodal polymer blend in which one polymer has a heat of fusion of about 50 J/g or less, and a second polymer has a heat of fusion of about 30 J/g or more.
• the nucleating agent may be employed to reduce the set time of a multi-modal polymer blend in which one polymer has a heat of fusion of about 65 J/g to about 85 J/g, and a second polymer has a heat of fusion of about 10 J/g to about 30 J/g.
• the nucleating agent may also be employed to reduce the set time of a multi-modal polymer blend in which one polymer has a heat of fusion of 80 J/g or more, and the second polymer has a heat of fusion of about 50 J/g or less.
• the nucleating agent may also be employed to reduce the set time of a multi-modal polymer blend in which one polymer has a heat of fusion of 50 J/g or more, and the second polymer has a heat of fusion of about 15 J/g or less.
• the weight ratio of first polymer to second polymer present in the blend may be 10:90 to 90: 10, or 20:80 to 80:20, or 30:70 to 70:30, or 40:60 to 60:40.
• the formulations disclosed herein have a Dot-T Peel of 1 Newton or more on Kraft Paper.
• a Dot T-Peel of 1 Newton may be considered a minimum performance requirement for an adhesive.
• an adhesive composition that demonstrates any measurable fiber tear has a Dot T-Peel of at least 1 Newton.
• Polymers employed in any of the polyolefin compositions of the invention are preferably derived from one or more monomers selected from the group consisting of propylene, ethylene, C 4 to C20 linear or branched olefins, and diolefins (particularly, C 4 to C 10 olefins).
• the term "monomer” or “comonomer” as used herein can refer to the monomer used to form the polymer, i.e., the unreacted chemical compound in the form prior to polymerization, and can also refer to the monomer after it has been incorporated into the polymer, also referred to herein as a "[monomer] -derived unit", which by virtue of the polymerization reaction typically has fewer hydrogen atoms than it does prior to the polymerization reaction.
• the polymer is predominantly propylene.
• Preferred comonomers include ethylene, butene, hexene, and octene, with ethylene being the most preferred comonomer.
• the crystallinity and heat of fusion of the polymer are affected by the comonomer content and the sequence distribution of the comonomer within the polymer. Generally, increased levels of comonomer will reduce the crystallinity provided by the crystallization of stereoregular propylene-derived sequences.
• the comonomer content and sequence distribution of the polymers can be measured using 13 C nuclear magnetic resonance (NMR) by methods well known to those skilled in the art.
• Comonomer content of discrete molecular weight ranges can be measured using methods well known to those skilled in the art, including Fourier Transform Infrared Spectroscopy (FTIR) in conjunction with samples by GPC, as described in Wheeler and Willis, Applied Spectroscopy, 1993, Vol. 47, pp. 1 128-1130.
• FTIR Fourier Transform Infrared Spectroscopy
• the comonomer (ethylene) content can be measured using the procedure described in Wheeler and Willis.
• Various test methods including GPC measurements methods and methods for determining ethylene content by NMR and the DSC measurements are described in U.S. Patent No. 6,525, 157, which is incorporated by reference herein in its entirety.
• Preferred polymers are semi-crystalline propylene-based polymers.
• the polymers may have a relatively low molecular weight, preferably about 100,000 g/mole or less.
• the polymer may comprise a comonomer selected from the group consisting of ethylene and linear or branched C 4 to C2 0 olefins and diolefins.
• the comonomer may be ethylene or a C 4 to C1 0 olefin.
• polymer as used herein includes, but is not limited to, homopolymers, copolymers, interpolymers, terpolymers, etc. and alloys and blends thereof. Further, as used herein, the term “copolymer” is meant to include polymers having two or more monomers, optionally with other monomers, and may refer to interpolymers, terpolymers, etc. The term “polymer” as used herein also includes impact, block, graft, random and alternating copolymers. The term “polymer” shall further include all possible geometrical configurations unless otherwise specifically stated. Such configurations may include isotactic, syndiotactic and random symmetries.
• Polypropylene as used herein includes homopolymers and copolymers of propylene or mixtures thereof. Products that include one or more propylene monomers polymerized with one or more additional monomers may be more commonly known as random copolymers (RCP) or impact copolymers (ICP). Impact copolymers are also known in the art as heterophasic copolymers.
• RCP random copolymers
• ICP impact copolymers
• Impact copolymers are also known in the art as heterophasic copolymers.
• “Propylene-based”, as used herein, is meant to include any polymer comprising propylene, either alone or in combination with one or more comonomers, in which propylene is the major component (i.e., greater than 50 mole% propylene). In any embodiment, the polymer may be a propylene-based elastomer.
• elastomer refers to a polymer which exhibits elasticity, i.e., the ability to regain shape after deformation, is above its glass transition temperature at room temperature, and exhibits elongation at break of preferably at least 80%, or more preferably at least 100%, or even more preferably at least 200%.
• the polyolefin composition may comprise one or more propylene-based polymers, which comprise propylene and from about 5 mole% to about 30 mole% of one or more comonomers selected from C 2 and C4-C10 a-olefins.
• the a-olefin comonomer units may derive from ethylene, butene, pentene, hexene, 4-methyl-l -pentene, octene, or decene.
• the embodiments described below are discussed with reference to ethylene and hexene as the a-olefin comonomer, but the embodiments are equally applicable to other copolymers with other a-olefin comonomers.
• the copolymers may simply be referred to as propylene-based polymers with reference to ethylene or hexene as the a-olefin.
• the polyolefin composition may include at least about 5 mole%, at least about 6 mole%, at least about 7 mole%, or at least about 8 mole%, or at least about 10 mole%, or at least about 12 mole% ethylene-derived or hexene-derived units.
• the copolymers may include up to about 30 mole%, or up to about 25 mole%, or up to about 22 mole%, or up to about 20 mole%, or up to about 19 mole%, or up to about 18 mole%, or up to about 17 mole% ethylene-derived or hexene-derived units, where the percentage by weight is based upon the total weight of the propylene-derived and a-olefin derived units.
• the polyolefin composition may include at least about 70 mole%, or at least about 75 mole%, or at least about 80 mole%, or at least about 81 mole% propylene-derived units, or at least about 82 mole% propylene-derived units, or at least about 83 mole% propylene-derived units; and in these or other embodiments, the copolymers may include up to about 95 mole%, or up to about 94 mole%, or up to about 93 mole%, or up to about 92 mole%, or up to about 90 mole%, or up to about 88 mole% propylene-derived units, where the percentage by weight is based upon the total weight of the propylene-derived and alpha-olefin derived units.
• the polyolefin composition may comprise from about 5 mole% to about 25 mole% ethylene-derived or hexene-derived units, or from about 8 mole% to about 20 mole% ethylene-derived or hexene-derived units, or from about 12 mole% to about 18 mole% ethylene-derived or hexene-derived units.
• the polyolefin composition may be characterized by a melting point (Tm), which can be determined by differential scanning calorimetry (DSC).
• Tm melting point
• DSC differential scanning calorimetry
• a “peak” in this context is defined as a change in the general slope of the DSC curve (heat flow versus temperature) from positive to negative, forming a maximum without a shift in the baseline where the DSC curve is plotted so that an endothermic reaction would be shown with a positive peak.
• the Tm of the polyolefin composition (as determined by DSC) may be less than about 1 15°C, or less than about 110°C, or less than about 100°C, or less than about 90°C. In any embodiment, the Tm of the polyolefin composition may be greater than about 25°C, or greater than about 30°C, or greater than about 35°C, or greater than about 40°C.
• the first crystallization temperature (Tel) of the polyolefin composition is less than about 100°C, or less than about 90°C, or less than about 80°C, or less than about 70°C, or less than about 60°C, or less than about 50°C, or less than about 40°C, or less than about 30°C, or less than about 20°C, or less than about 10°C.
• the Tel of the polyolefin composition is greater than about 0°C, or greater than about 5°C, or greater than about 10°C, or greater than about 15°C, or greater than about 20°C.
• the Tel lower limit of the polyolefin composition may be 0°C, 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, and 70°C; and the Tel upper limit temperature may be 100°C, 90°C, 80°C, 70°C, 60°C, 50°C, 40°C, 30°C, 25°C, and 20°C with ranges from any lower limit to any upper limit being contemplated.
• the second crystallization temperature (Tc2) of the polyolefin composition is less than about 100°C, or less than about 90°C, or less than about 80°C, or less than about 70°C, or less than about 60°C, or less than about 50°C, or less than about 40°C, or less than about 30°C, or less than about 20°C, or less than about 10°C.
• the Tc2 of the polymer is greater than about 0°C, or greater than about 5°C, or greater than about 10°C, or greater than about 15°C, or greater than about 20°C.
• the Tc2 lower limit of the polyolefin composition may be 0°C, 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, and 70°C; and the Tc2 upper limit temperature may be 100°C, 90°C, 80°C, 70°C, 60°C, 50°C, 40°C, 30°C, 25°C, and 20°C with ranges from any lower limit to any upper limit being contemplated.
• the polyolefin composition may have a density of from about 0.85 g/cm 3 to about 0.92 g/cm 3 , or from about 0.86 g/cm 3 to about 0.90 g/cm 3 , or from about 0.86 g/cm 3 to about 0.89 g/cm 3 at room temperature as measured per the ASTM D- 792 test method.
• the semi-crystalline polymer can have a weight average molecular weight (Mw) of from about 5,000 to about 500,000 g/mol, or from about 7,500 to about 300,000 g/mol, or from about 10,000 to about 200,000 g/mol, or from about 25,000 to about 175,000 g/mol.
• Mw weight average molecular weight
• molecular weight may be determined by size exclusion chromatography (SEC) by using a Waters 150 gel permeation chromatograph equipped with the differential refractive index detector and calibrated using polystyrene standards.
• SEC size exclusion chromatography
• the polyolefin composition may have a viscosity (also referred to a Brookfield viscosity or melt viscosity), measured at 190°C and determined according to ASTM D-3236 from about 100 cP to about 1,000,000,000 cP, or from about 1,000 to about 100,000,000 cP, or from about 2,000 to about 10,000,000 cP, or from about 2,500 to about 7,500,000 cP, or from about 3,000 to about 5,000,000 cP, or from about 3,500 to about 3,000,000 cP, or from about 4,000 to about 1,000,000 cP, or from about 4,500 to about 750,000 cP, or from about 5,000 to about 500,000 cP, or from about 5,500 to about 450,000 cP, or from about 6,000 to about 400,000 cP.
• a viscosity also referred to a Brookfield viscosity or melt viscosity
• the polyolefin composition may be characterized by its viscosity at 190°C.
• the semi-crystalline polymer may have a viscosity that is at least about 100 cP (centipoise), or at least about 500 cP, or at least about 1,000 cP, or at least about 1,500 cP, or at least about 2,000 cP, or at least about 3,000 cP, or at least about 4,000 cP, or at least about 5,000 cP.
• the polyolefin composition may be characterized by an viscosity at 190°C of less than about 100,000 cP, or less than about 75,000 cP, or less than about 50,000 cP, or less than about 25,000 cP, or less than about 20,000 cP, or less than about 15,000 cP, or less than about 10,000 cP, or less than about 5,000 cP with ranges from any lower limit to any upper limit being contemplated.
• one or more of the polymers described herein may be blended with another polymer, such as another polymer described herein, to produce a physical blend of polymers, preferably a multimodal polymer blend.
• blend refers to a mixture of two or more polymers.
• multimodal refers to a blend of two or more distinct polymer species in which each species is distinguishable from another species present in the blend on the basis of at least one chemical or physical property selected from the group consisting of molecular weight, melt viscosity, comonomer content, heat of fusion, and crystallinity.
• the first polymer and second polymer of the blend may have a difference in heat of fusion of about 20 J/g or more, or more preferably about 30 J/g or more.
• the first polymer may have a heat of fusion of about 50 J/g or more and the second polymer may have a heat of fusion of about 30 J/g or less.
• the first polymer may have a heat of fusion of about 65 to about 85 J/g and the second polymer may have a heat of fusion of about 10 J/g to about 20 J/g.
• the first and second polymer may each be, independently, a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to Cio olefin.
• each polymer of the blend may have a propylene content of more than 50 mole%.
• Particularly advantageous adhesive properties can be achieved by employing a multimodal polymer blend that employs an exceptionally low crystalline propylene-based polymer in combination with a higher crystalline propylene-based polymer.
• the exceptionally low crystalline propylene-based polymer may be a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C 10 olefin, and has a heat of fusion of about 15 J/g or less.
• the exceptionally low crystalline propylene-based polymer may be a homopolymer of propylene or a copolymer of propylene and ethylene, butene, hexene, or octene.
• the exceptionally low crystalline propylene-based may be a homopolymer of propylene or a copolymer of propylene and ethylene. In any embodiment, the exceptionally low crystalline propylene-based polymer may have a propylene content of more than 50 mole%.
• the higher crystalline propylene-based polymer that is blended with the exceptionally low crystalline propylene-based polymer may be a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C 10 olefin, and has a heat of fusion of about 50 J/g or more, or 55 J/g or more, or 60 J/g or more, or 65 J/g or more, or 75 J/g or more. In an exemplary embodiment, the higher crystalline propylene-based polymer has a heat of fusion of about 65 J/g to about 85 J/g.
• the higher crystalline propylene-based polymer may be a homopolymer of propylene or a copolymer of propylene and ethylene, butene, hexene, or octene. In any embodiment, the higher crystalline propylene- based polymer is a homopolymer of propylene or a copolymer of propylene and ethylene. In any embodiment, the higher crystalline propylene-based polymer may have a propylene content of more than 50 mole%.
• particularly advantageous adhesive properties can be achieved by using an exceptionally high crystalline propylene-based polymer in combination with a lower crystalline propylene-based polymer.
• the exceptionally high crystalline propylene-based polymer may be a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C 10 olefin, and has a heat of fusion of about 80 J/g or more.
• the exceptionally high crystalline propylene-based polymer may be a homopolymer of propylene or a copolymer of propylene and ethylene, butene, hexene, or octene.
• the exceptionally high crystalline propylene-based polymer is a homopolymer of propylene or a copolymer of propylene and ethylene. In any embodiment, the exceptionally high crystalline propylene-based polymer may have a propylene content of more than 50 mole%.
• the lower crystalline propylene-based polymer that is blended with the exceptionally high crystalline propylene-based polymer may be a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C 10 olefin, and has a heat of fusion of about 50 J/g or less, or more preferably about 25 J/g or less.
• the lower crystalline propylene-based polymer has a heat of fusion of about 10 J/g to about 20 J/g.
• the lower crystalline propylene-based polymer may be a homopolymer of propylene or a copolymer of propylene and ethylene, butene, hexene, or octene. In any embodiment, the lower crystalline propylene-based polymer is a homopolymer of propylene or a copolymer of propylene and ethylene. In any embodiment, the lower crystalline propylene-based polymer may have a propylene content of more than 50 mole%. In any embodiment, the lower crystalline propylene-based polymer has a heat of fusion of 45 J/g or less, 40 J/g or less, 35 J/g or less, or 30 J/g or less.
• the relative weight percentages of polymers of blend may vary depending on the application of the hot melt adhesive formulation.
• the higher crystalline polymer may about 10% to about 90% of the polymer blend, or about 20% to about 80% of the polymer blend, or about 30% to about 70% of the polymer blend, or about 40% to about 60% of the polymer blend.
• nucleating agent refers to a component that when added to the adhesive composition increases the temperature at which the polyolefin composition begins to solidify or crystallize from a molten state. Without being bound by theory, it is believed that such a component that is compatible with the polyolefin composition forms nucleation sites which promote the alignment and crystallization of the polyolefin polymer molecules adjacent to the nucleation sites.
• the nucleating agent may be a solid particle having a size suitable for promoting a nucleating effect.
• the nucleating agent may be a polymer that is compatible with the polyolefin and that crystallizes at a higher temperature than the polyolefin to promote a nucleating effect when the adhesive composition cools from a molten state.
• the nucleating agent may be selected from the group consisting of sodium benzoate, talc, glycerol alkoxide salts, cyclic carboxylic acid salts, bicyclic carboxylic acid salts, glycerolates, and hexahydrophtalic acid salts.
• Nucleating agents include HYPERFORMTM additives, such as HPN-68, HPN-68L, HPN-20, HPN-20E, MILLADTM additives (e.g., MILLADTM 3988) (Milliken Chemicals, Spartanburg, SC) and organophosphates such as NA-1 1 and NA-21 (Amfine Chemicals, Allendale, NJ).
• the nucleating agent may comprise at least one bicyclic carboxylic acid salt.
• the nucleating agent is bicycloheptane dicarboxylic acid, disodium salt such as bicyclo [2.2.1] heptane dicarboxylate.
• the nucleating agent may be a blend of components comprising bicyclo [2.2.1] heptane dicarboxylate, disodium salt, 13- docosenamide, and amorphous silicon dioxide.
• the nucleating agent may be cyclohexanedicarboxylic acid, calcium salt or a blend of cyclohexanedicarboxylic acid, calcium salt, and zinc stearate.
• the nucleating agent may be a metal salt of Formula (I),
• R 1 to R 10 are independently of one another a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 9 carbon atoms, an amino group, an alkylamine group having 1 to 9 carbon atoms, a halogen atom, a phenyl group, or a group represented by the formula, R— (R'— 0)n— , R being an alkyl group having 1 to 3 carbon atoms, R' being an alkylene group having 2 or 3 carbon atoms, and n being an integer of 1 to 4; any two alkyl groups of R 1 to R 10 may be linked to each other, thereby forming a carbon ring having 3 to 6 carbon atoms; and R 1 and R 2 have a trans or cis configuration with each other.
• R 1 to R 10 in formula (I) representing the metal salt are a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group, a methylamino group, an ethylamino group, a dimethylamino group, a diethylamino group, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
• R-(R'-O) n- examples of the group represented by the formula, R-(R'-O) n-, contained in formula (I) are as follows: CH3-(CH2CH2-0)-, CH3(CH2CH2- -O) 2-, CH3(CH2CH2-0) 3-, CH3(CH2CH2-0).sub.4-, C2H5-(CH2CH2-0)-, C2H5(CH2CH2-0) 2-, C2H5(CH2CH2-0)3-, C3H7-(CH2CH2-)-, C3H7(CH2CH2-0) 2-, C3H7(CH2CH2-0) 3-, CH3-(CH(CH3)CH2-0)-, CH3(CH(CH3)CH2-0) 2-, C2H5- (CH(CH3)CH2-0)-, and C2H5(CH(CH3)CH2-0) 2-.
• R 1 to R 10 are independently of one another preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms such as a methyl group, an ethyl group and a propyl group.
• a more preferable metal salt is calcium 1 ,2-cyclohexanedicarboxylate represented by the following formula:
• the metal salt may be combined with a dispersing agent.
• the dispersing agent are an aliphatic acid such as an aliphatic acid having 10 to 24 carbon atoms; an alkyl ester of such an aliphatic acid; an alkali or alkaline-earth metal salt of such an aliphatic acid; alcohols having 10 to 30 carbon atoms; a polyalcohol; and an ester of such a polyalcohol.
• a metal salt of an aliphatic acid is preferred.
• Examples of the alkali metal are sodium, potassium and lithium, and examples of the alkaline-earth metal are calcium, magnesium and zinc.
• Examples of the polyalcohol are glycerin, ethylene glycol, propylene glycol, pentaerythritol, dipentaerythritol, tripentaerythritol, and sorbitol.
• the metal salt is preferably a particulate form, which has an average particle diameter of usually 0.01 to 10 ⁇ , preferably 0.01 to 5 ⁇ , and further preferably 0.01 to 3 ⁇ , measured with a laser diffraction type-particle size distribution measurement apparatus such as a HELOSTM measurement apparatus (Sympatec GmbH).
• the calcium 1,2-cyclohexanedicarboxylate may be a commercially-available metal salt such as HYPERFORMTM HPN-20E (trademark of Milliken and Company), which contains 66% by weight of calcium 1,2-cyclohexanedicarboxylate as a principal component.
• HYPERFORMTM HPN-20E trademark of Milliken and Company
• Paragraph A An adhesive composition comprising:
• a polyolefin composition comprising a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C 10 alpha-olefin;
• nucleating agent effective for decreasing the set time for the adhesive composition by at least 10% in comparison to an otherwise identical adhesive composition in which the nucleating agent is absent;
• the adhesive composition has a Dot T-Peel of 1 Newton or more on Kraft paper.
• Paragraph B The adhesive composition of Paragraph A, wherein the nucleating agent is a metal salt.
• Paragraph C The adhesive composition of Paragraph A, wherein the nucleating agent is an organic compound having a crystallization temperature greater than the crystallization temperature of the polyolefin composition.
• Paragraph D The adhesive composition of any of Paragraphs A-C, wherein the nucleating agent is effective to increase the onset crystallization temperature of the polyolefin composition relative to the adhesive composition in which the nucleating agent is absent.
• Paragraph E The adhesive composition of any of Paragraphs A-D, wherein the nucleating agent is effective to increase the onset crystallization temperature of the polyolefin composition by at least 10°C relative to the adhesive composition in which the nucleating agent is absent.
• Paragraph F The adhesive composition of any of Paragraphs A-E, wherein the nucleating agent may be selected from the group consisting of sodium benzoate, talc, glycerol alkoxide salts, cyclic carboxylic acid salts, bicyclic carboxylic acid salts, glycerolates, and hexahydrophtalic acid salts.
• the nucleating agent may be selected from the group consisting of sodium benzoate, talc, glycerol alkoxide salts, cyclic carboxylic acid salts, bicyclic carboxylic acid salts, glycerolates, and hexahydrophtalic acid salts.
• Paragraph G The adhesive composition of Paragraph F, wherein the nucleating agent comprises a salt of bicyclo [2.2.1] heptane dicarboxylate.
• Paragraph H The adhesive composition of any of Paragraphs A-G, wherein the adhesive composition comprises about 25 wt% wax or less.
• Paragraph I The adhesive composition of any of Paragraphs A-H, wherein the adhesive composition comprises about 5 wt% wax or less.
• Paragraph J The adhesive composition of any of Paragraphs A-G, wherein the adhesive composition comprises substantially no wax.
• Paragraph K The adhesive composition of any of Paragraphs A- J, wherein the polyolefin composition comprises a copolymer of propylene and ethylene.
• Paragraph L The adhesive composition of any of Paragraphs A-K, wherein the polyolefin composition comprises a blended multimodal polymer.
• Paragraph M The adhesive composition of Paragraph L, wherein the blended multimodal polymer comprises a first polymer, wherein the first polymer is a copolymer of propylene and ethylene or a C 4 to Cio olefin; and a second polymer, wherein the second polymer is a copolymer of propylene and ethylene or a C 4 to Cio olefin.
• Paragraph N The adhesive composition of Paragraph M, wherein the first polymer and second polymer have a difference in heat of fusion of about 20 J/g or more.
• Paragraph O The adhesive composition of Paragraph N, wherein the difference in heat of fusion between the first polymer and second polymer is about 30 J/g or more.
• Paragraph P The adhesive composition of Paragraph N, wherein the first polymer has a heat of fusion of about 50 J/g or more, and the second polymer has a heat of fusion of about 30 J/g or less.
• Paragraph Q The adhesive composition of Paragraph P, wherein the first polymer has a heat of fusion of about 65 J/g to about 85 J/g and the second polymer has a heat of fusion of about 10 J/g to about 30 J/g.
• Paragraph R The adhesive composition of Paragraph O, wherein the first polymer has a heat of fusion of about 80 J/g or more, and the second polymer has a heat of fusion of about 50 J/g or less.
• Paragraph S The adhesive composition of Paragraph O, wherein the first polymer has a heat of fusion of about 50 J/g or more, and the second polymer has a heat of fusion of about 15 J/g or less.
• Paragraph T An adhesive composition comprising:
• a polyolefin composition comprising a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C 10 alpha-olefin;
• nucleating agent effective for decreasing the set time for the adhesive composition in comparison to an otherwise identical adhesive composition in which the nucleating agent is absent, wherein the nucleating agent is an inorganic solid particle or an organic component having a crystallization temperature greater than that of the polyolefin composition; wherein the adhesive composition has a Dot T-Peel of 1 Newton or more on Kraft paper.
• Paragraph U An adhesive composition comprising:
• a polyolefin composition comprising a homopolymer of propylene or a copolymer of propylene and ethylene or a C 4 to C 10 alpha-olefin; a nucleating agent effective for decreasing the set time for the adhesive composition in comparison to an otherwise identical adhesive composition in which the nucleating agent is absent, wherein the nucleating agent is an organic metal salt; and
• the adhesive composition has a Dot T-Peel of 1 Newton or more on Kraft paper.
• Paragraph V The adhesive composition of any of Paragraphs A-U, wherein the nucleating agent is present in an amount of 200 to 5000 ppm.
• compositions were made by preheating components to 180°C in a glass beaker and blended by simple manual stirring using a spatula.
• the composition of each adhesive is described in TABLE 1. Unless otherwise specified, the numerical values are expressed in weight percentages.
• Each of the compositions was analyzed to determine its open time, set time, fiber tear at room temperature and under refrigeration, and viscosity. The results of this analysis are also reported in TABLE 1.
• PBE1 is a propylene based elastomer with a viscosity at 190°C of 1 122 mPas and a heat of fusion of 45 J/g.
• PBE2 is a propylene based elastomer with a viscosity at 190°C of 865 mPas and a heat of fusion of 41 J/g.
• LixarTM 127 is a polyolefin adhesive base polymer resin available from ExxonMobil Chemical Company.
• EscoreneTM UL 40028 is an ethylene vinyl acetate copolymer resin available from ExxonMobil Chemical Company.
• EscoreneTM UL 02528 is an ethylene vinyl acetate copolymer resin available from ExxonMobil Chemical Company.
• SasolwaxTM C80 is a Fischer-Tropsch wax having a melting point of 80°C available from Sasol wax a division of Sasol limited, South Africa.
• SasolwaxTM HI is a Fischer-Tropsch wax having a melting point of 98°C available from Sasol wax a division of Sasol limited, South Africa.
• MillikenTM HPN 20e is a metal salt of 1 ,2-cyclohexanedicarboxylate available from Milliken Chemical, a division of Milliken & Company.
• EscorezTM 2206LC is an aromatic modified aliphatic hydrocarbon resin expressing a softening point of 92°C available from ExxonMobil Chemical Company.
• MAPP 40 is a maleated polypropylene with a softening point of 300-350 deg F, a viscosity at 150 C of 200-400 cPs, and an acid number of 40-50 available from SSI Chusei, Inc located in Pasadena, TX.
• A-CTM 596 is a propylene maleic anhydride copolymer available from Honeywell Specialty Adhesives.
• IrganoxTM 1010 is a hindered phenolic antioxidant available from BASF SE Corporation located in Ludwigshafen, Germany.
• Fiber tear describes the bond strength of the adhesive to the substrate and was measured at room temperature (RT) and -18°C.
• Fiber tear is a visual measurement as to the amount of paper substrate fibers that are attached to a bond after the substrates are torn apart. 100% fiber tear means the adhesive is stronger than the substrate and 100% of the adhesive is covered in substrate fibers. 0% fiber tear means the adhesive does not bond at all and simply pops off the substrate.
• Fiber tear was determined by bonding together substrates with the adhesive after the molten adhesive (180°C) has been dropped onto one of the substrates with an eye dropper. The second substrate was placed on top of the adhesive, and a 500g weight was placed on top of the second substrate for even application. The adhesive was allowed to cool at the referenced temperature for at least one hour. The substrates were then torn apart and the adhesive was inspected for fiber tear.
• Set time is defined as the minimal holding time to build bond cohesion requiring more than 10kg force to break the bond.
• Set time was determined by bonding together substrates with the adhesive after the molten adhesive (180°C) has been dropped onto one of the substrates with an eye dropper. The second substrate was placed on top of the adhesive, and a 500g weight was placed on top of the second substrate for even application. After a predetermined interval of time the second substrate is removed and checked for fiber tear. If no fiber tear was found, a longer interval of time was tried. This continued until fiber tear is found. This length of time was reported as the set time.
• Open time is defined as the maximum open time after which it remains possible to build a bond stronger than 10kg force. Open time was determined by bonding together substrates with the adhesive after the molten adhesive (180°C) has been dropped onto one of the substrates with an eye dropper. The second substrate was placed on top of the adhesive, and a 500g weight was placed on top of the second substrate for even application. The bonded specimen was examined to determine the longest time period, between application of the adhesive to one surface and mating with a second surface, which allows at least 50% fiber tear.
• compositions E and F exhibited set time performances equal to that of the desired performance benchmarks. Notably, such performance was achieved without using a Fischer- Tropsch wax and using higher polymer loadings. Open time and fiber tear performance were also exceptional for compositions E and F.
• FIG. 1 Peeling force as a function of application time for each of the adhesive blends is illustrated in FIG. 1.
• the adhesive compositions comprising a nucleating agent build up strength quickly at about 0.7 seconds after application. It is believed that this phenomenon is effected by the crystallization of the organic component of the metal salt as the adhesive composition cools, which in turn promotes the crystallization and solidification of the base polymer of the adhesive composition starting at sites adjacent to the nucleating agent as the adhesive composition cools.
• the presence of the nucleating agent may increase the onset crystallization temperature of the polyolefin composition, e.g., by at least 2°C, 3°C, 5°C, or 7°C relative to the adhesive composition in which the nucleating agent is absent.
• the presence of the nucleating agent in Composition F increased the onset crystallization temperature of the composition (relative to Composition D) to 97.62°C from 90.26°C.
• the nucleating agent may be provided in an amount effective to increase the onset crystallization temperature of the polyolefin composition, e.g., by at least 2°C, 3°C, 5°C, or 7°C relative to the adhesive composition in which the nucleating agent is absent.

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