Hot melt adhesive compositions containing propylene copolymers and methods of using same

Abstract

To provide a hot melt adhesive that, as a construction adhesive, has adequate peel performance and shear strength, has a sufficiently low viscosity at a desired application temperature (which preferably is as low as possible), and is sprayable at the application temperature.SOLUTION: There is provided a hot melt adhesive composition comprises: a first polymer comprising a unimodal copolymer of propylene and ethylene and having a weight average molecular weight of between about 5,000 and 60,000 daltons; a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 daltons; a tackifying resin having a Ring and Ball softening point of at most 115°C; and a plasticizer. The composition demonstrates good peel strength and good shear resistance and is sprayable, with a sufficiently low viscosity, at low application temperatures, such as at about 121°C.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e) of U.S. patent application Ser. No. 62 / 624,369, filed Jan. 31, 2018.

[0002] This invention relates to hot melt adhesives, and more particularly to polyolefin-based hot melt adhesives, which are useful in bonding a variety of substrates together and are particularly useful as construction adhesives for the manufacture of disposable consumer articles such as diapers, feminine sanitary napkins, adult incontinence products, medical gowns, and the like. [Background technology]

[0003] Hot melt adhesives typically exist as solid materials at ambient temperatures and can be converted to flowable liquids by the application of heat. These adhesives are particularly useful in manufacturing a variety of disposable goods, often requiring the bonding of various substrates. Specific applications include disposable diapers, hospital pads, feminine sanitary napkins, panty shields, surgical drapes, and adult incontinence briefs, collectively known as disposable nonwoven hygiene products. Other diverse applications involve paper products, packaging materials, automotive headliners, appliances, tapes, and labels. In most of these applications, the hot melt adhesive is heated to its molten state and then applied to a substrate, often referred to as the primary substrate. A second substrate, often referred to as the secondary substrate, is then immediately brought into contact with the first substrate and compressed against it. The adhesive solidifies upon cooling, forming a strong bond. A major advantage of hot melt adhesives is the absence of a liquid carrier, as is the case with water- or solvent-based adhesives, thereby eliminating the costly process associated with solvent removal.

[0004] For many applications, hot melt adhesives are often extruded directly onto a substrate in the form of a thin film or beads using a piston or gear pump device. In this case, the substrate is in intimate contact with a hot die under pressure. The temperature of the die must be maintained sufficiently above the melting point of the adhesive to allow the molten hot melt material to flow smoothly through the application nozzle. Many applications, particularly those in food packaging and disposable nonwoven hygiene article manufacturing, often involve bonding of precise, heat-sensitive substrates such as gauge plastic thin films. This imposes an upper limit on the coating temperature for hot melt adhesive applications. Currently commercially available hot melts are typically formulated to have a coating temperature below 200°C, preferably below 150°C, to avoid substrate baking or distortion.

[0005] In addition to direct coating, several indirect or non-contact coating methods have been developed that allow hot melt adhesives to be spray-coated onto substrates from a distance with the assistance of compressed air. These non-contact coating techniques include conventional spiral spraying, Omega™, Surewrap™, and various forms of meltblown coating. However, with indirect methods, the viscosity of the adhesive must be sufficiently low at the application temperature to obtain an acceptable coating pattern, typically in the range of 2,000 to 30,000 mPa·s, preferably 2,000 to 15,000 mPa·s. Many other physical factors of the adhesive, particularly its rheological properties, play a role in determining the sprayability of a hot melt. Many commercially available polyolefin hot melt products are not suitable for spray application. There are no accepted theoretical models or guidelines for predicting sprayability, which is determined empirically by the application equipment.

[0006] Hot melt adhesives are typically organic materials consisting of polymers, plasticizers, tackifying resins, and antioxidant packages. Other ingredients, such as waxes, fillers, colorants, and UV absorbers, can also be used to modify adhesive properties or provide special properties. These organic components are prone to thermal decomposition under the adhesive's coating conditions. For example, certain widely used commercial hot melt adhesives based on styrene-isoprene-styrene (SIS) triblock copolymers can experience a viscosity loss of approximately 50 percent from their initial value when subjected to temperatures of 175°C for 24 hours. Styrene-butadiene-styrene (SBS)-based hot melts can experience problems due to crosslinking under similar conditions. Crosslinking can result in a dramatic increase in viscosity and, due to the formation of a three-dimensional polymer network, can ultimately render the adhesive non-flowable. Viscosity changes are often accompanied by charring, gelation, and film formation on the molten material. Decomposition will inevitably lead to a deterioration in adhesive properties and performance. In addition, such decomposition can cause equipment damage. The rate of degradation is temperature dependent; the higher the temperature, the faster the degradation. Therefore, the degradation can be slowed down by reducing the coating temperature of the adhesive.

[0007] Hot melt "construction adhesives" for disposable consumer hygiene articles bond various nonwoven materials to low surface energy thermoplastic films such as polylactic acid, polyethylene, or untreated polypropylene. The use of thinner polyolefin backsheets in the manufacture of disposable articles necessitates the use of lower viscosity hot melts to prevent burn-through and deformation when the adhesive is applied. Construction adhesives should have good shear strength, but also strong peel strengths, such as 1 or 2 grams per square meter, especially at low add-on levels.

[0008] Efforts have been made to develop hot melt adhesives. U.S. Patent Application Publication No. 2015 / 0322302 discloses a low-application-temperature hot melt adhesive comprising an olefin copolymer having an average melt index greater than 5 g / 10 min but less than about 35 g / 10 min at 190°C. This adhesive is particularly useful in the construction of nonwoven articles. U.S. Patent Application Publication No. 9,109,143 discloses a hot melt adhesive comprising two polypropylene-based copolymers having an average molecular weight of 100,000 daltons or less. U.S. Patent Application Publication No. 2016 / 0376478 discloses an adhesive composition comprising 30 to 80 wt% of a polymer blend and 2 to 20 wt% of an oil. The blend has first and second propylene-based polymers that differ from each other in some way. The difference can be measured, for example, by the comonomer content, heat of fusion, crystallinity, branching index, weight-average molecular weight, and / or polydispersity of the two polymers. The adhesive may further include a higher molecular weight propylene-based polymer in an amount of about 1% to about 10% by weight to allow for higher oil content. Summary of the Invention [Problem to be solved by the invention]

[0009] It would be advantageous to provide a hot melt adhesive that would perform particularly well as a construction adhesive. To that end, it is desirable for the adhesive to have adequate peel performance and shear strength, a low enough viscosity at the desired application temperature (preferably as low as possible), and be sprayable at the application temperature. By "sprayable" we mean that the adhesive will conform to the desired spray pattern with consistency and with minimal adhesive loss. Embodiments of the present invention achieve all of these requirements. [Means for solving the problem]

[0010] According to an embodiment of the present invention, a hot melt adhesive composition comprises: (a) about 30% to about 72% by weight of a first polymer comprising a monomodal copolymer of propylene and ethylene and having a weight average molecular weight of about 5,000 to 60,000 Daltons; (b) about 0.1% to about 8% of a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 Daltons; (c) about 25% to about 65% by weight of a tackifying resin having a Ring and Ball softening point of up to 115°C; and (d) about 2% to about 25% by weight of a plasticizer, wherein the weight ratio of the first polymer to the second polymer is about 500:1 to 9:1, and the viscosity of the composition is about 35,000 cP or less at 121°C.

[0011] According to another embodiment of the present invention, a hot melt adhesive composition comprises: (a) a first polymer comprising a monomodal copolymer of propylene and ethylene and having a weight average molecular weight of about 5,000 to 60,000 daltons; (b) a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 daltons; a tackifying resin having a Ring and Ball softening point of at most 115°C; and a plasticizer, wherein the viscosity of the composition is about 35,000 cP or less at 121°C, and the first polymer, the second polymer, the tackifying resin, and the plasticizer are combined. The donor resin and plasticizer are present in amounts effective to provide a hot melt adhesive composition that has: (1) an initial peel force of at least 150 grams force and at least 250 grams force after aging at 54.5°C when applied at a 2 gsm add-on between a polyethylene film and a nonwoven layer; (2) an initial peel force of at least 100 grams force when applied at a 1 gsm add-on between a polyethylene film and a nonwoven layer; and (3) a shear value of at least 50 minutes at 37.8°C when applied between two nonwoven layers and using a 250 gram weight.

[0012] According to another embodiment of the present invention, a method for producing a laminate comprises applying a hot melt adhesive composition according to any embodiment of the present invention in a molten state to a primary substrate and conforming a secondary substrate to the primary substrate by contacting the secondary substrate with the adhesive composition. In embodiments where a hot melt adhesive is used as the construction adhesive, the primary substrate is a polyethylene film and the secondary substrate is a nonwoven layer.

[0013] It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention. [Brief explanation of the drawings]

[0014] [Figure 1] 1 shows peel performance after 1 week aging versus shear strength for exemplary formulations of the present invention and two comparative examples, with circle size representing the standard deviation. [Figure 2] 1 shows the release performance of exemplary formulations of the present invention at three different application temperatures, both initially and after various aging environments. [Figure 3] 1 shows peel performance after 1 week aging versus shear strength for exemplary formulations of the present invention and two comparative examples, with circle size representing the standard deviation. DETAILED DESCRIPTION OF THE INVENTION

[0015] According to an embodiment of the present invention, a hot melt adhesive composition comprises: (a) about 30% to about 72% by weight of a first polymer comprising a monomodal copolymer of propylene and ethylene and having a weight average molecular weight of about 5,000 to 60,000 Daltons; (b) about 0.1% to about 8% of a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 Daltons; (c) about 25% to about 65% by weight of a tackifying resin having a Ring and Ball softening point of up to 115°C; and (d) about 2% to about 25% by weight of a plasticizer, wherein the weight ratio of the first polymer to the second polymer is about 500:1 to 9:1, and the viscosity of the composition (measured by ASTM D3236 using a Brookfield viscometer at 121°C) is about 35,000 cP or less. Unless otherwise specified, all percentages herein are by weight based on the total weight of the adhesive.

[0016] An embodiment of the present invention is an adhesive based on a mixture of a low molecular weight first polymer and a high molecular weight second polymer at a relatively high weight ratio of first polymer to second polymer. In a preferred embodiment, the weight ratio of first polymer to second polymer is about 200:1 to 9:1, preferably about 75:1 to about 10:1, and most preferably about 50:1 to about 15:1. When a numerical range of a property or amount of a component (inclusive of this ratio) is provided herein, the invention includes that property or amount range extending from the lower limit of the first range and the upper limit of the second range. Thus, by way of example, the invention includes ranges of weight ratios of first polymer to second polymer of about 200:1 to 15:1, about 75:1 to about 9:1, and about 50:1 to about 10:1. Adhesives according to embodiments of the present invention exhibit excellent shear strength and peel resistance, even at low add-on levels, such as 1 or 2 grams per square meter, and maintain a viscosity low enough to be sprayed at relatively low temperatures. Such properties make the adhesives of the present invention useful in hygiene, construction and packaging applications.

[0017] The first polymer of the present invention is unimodal, meaning that it does not constitute a blend or mixture of two polymers or two different grades of the same polymer. For example, the unimodal first polymer of the present invention is not a mixture of two polymers with different average molecular weights. That is, the unimodal first polymer is the result of a single process for producing the polymer and is not a mixture of two different polymers or two different grades of the same polymer (i.e., the same polymer with two different average molecular weights). Therefore, the properties of the unimodal first polymer of the present invention, such as molecular weight, generally have a bell-shaped curve. The unimodality of the first polymer exists with respect to all of its properties, including comonomer content, heat of fusion, crystallinity, branching index, melting point, glass transition temperature, density, and polydispersity, in addition to molecular weight. In an embodiment of the present invention, the second polymer is also unimodal.

[0018] Typically, the weight-average molecular weight of the first polymer is about 5,000 to 60,000 daltons. Preferably, the weight-average molecular weight of the first polymer is about 20,000 to about 55,000 daltons, more preferably about 30,000 to about 52,000 daltons, even more preferably about 35,000 to about 50,000 daltons, and most preferably about 40,000 to about 48,000 daltons. Typically, the weight-average molecular weight of the second polymer is about 100,000 to 250,000 daltons. Preferably, the weight-average molecular weight of the second polymer is about 100,000 to about 200,000 daltons, more preferably about 100,000 to about 150,000 daltons, and most preferably about 105,000 to about 125,000 daltons. The weight average molecular weight is characterized using High Temperature Size Exclusion Chromatograph (SEC) using a polystyrene reference standard.

[0019] The first and second polymers can have heats of fusion that vary widely and may be the same or different. Preferably, the first polymer has a heat of fusion of about 5 to about 35 J / g, preferably about 10 to about 29 J / g, more preferably about 15 to about 25 J / g, and most preferably about 18 to about 22 J / g. Preferably, the second polymer has a heat of fusion of about 2.5 to about 25 J / g, preferably about 3 to about 15 J / g, more preferably about 3.5 to about 10 J / g, and most preferably about 6 to about 9 J / g. The heat of fusion values ​​provided herein are determined according to ASTM E793-01, "Standard Test Method for Enthalpies of Fusion and Crystallization by Differential Scanning Calorimetry," except that a scanning temperature of 20°C per minute was used instead of 10°C per minute.

[0020] The polydispersity index of the first and second polymers can vary over a wide range and can be the same or different. The polydispersity index of the two polymers is preferably from about 1.5 to about 6, more preferably from about 1.8 to about 5, even more preferably from about 2 to about 3, and most preferably from about 2.2 to about 2.8.

[0021] Both the first and second polymers are composed predominantly of propylene units, meaning that they contain at least 50 weight percent propylene. Preferably, the first and second polymers have an ethylene content of from about 5% to about 25%, more preferably from about 7% to about 20%, even more preferably from about 9% to about 17%, and most preferably from about 10% to about 15%. The first and second polymers may have the same or different ethylene contents.

[0022] The melting temperatures of the first and second polymers, also referred to as melting points, can vary over a wide range. Preferably, the melting temperature of the first polymer is from about 70°C to about 130°C. More preferably, the melting temperature of the first polymer is from about 75°C to about 125°C, even more preferably from about 85°C to about 115°C, and most preferably from about 90°C to about 110°C. Preferably, the melting temperature of the second polymer is from about 35°C to 100°C. More preferably, the melting temperature of the second polymer is from about 40°C to about 90°C, even more preferably from about 50°C to about 80°C, and most preferably from about 55°C to about 75°C. The melting temperatures of the first and second polymers may be the same or different. As described herein, melting temperature is measured using differential scanning calorimetry (DSC) according to ASTM E-794-01, except for one change in the test in that a scanning temperature of 20°C per minute was used instead of 10°C per minute ("DSC melting point").

[0023] The glass transition temperatures of the first and second polymers can also vary widely. Preferably, the glass transition temperatures of the first and second polymers are from about −45° C. to about −5° C. More preferably, the glass transition temperatures are from −35° C. to −15° C., even more preferably from about −32° C. to −20° C., and most preferably from about −30° C. to −22° C. The glass transition temperatures of the first and second polymers can be the same or different. As described herein, glass transition temperatures are measured using differential scanning calorimetry (DSC) according to ASTM E-794-01, with one change in the test being that a scanning temperature of 20° C. per minute was used instead of 10° C. per minute.

[0024] The hot melt adhesive composition of the present invention also comprises a tackifying resin (also referred to herein as a "tackifier") having a Ring and Ball softening point of up to 115°C. As defined herein, a tackifier can be molecular or macromolecular, and is generally a compound derived from natural sources or chemical processes or a combination thereof, or a polymer of very low molecular weight compared to common polymers, that generally enhances the adhesive properties of the final hot melt adhesive composition. Exemplary resins include C5 / C9 hydrocarbon resins, synthetic polyterpenes, rosin, rosin esters, natural terpenes, etc. More particularly, useful tackifying resins include any compatible resin or mixture thereof, such as (1) natural and modified rosins, including gum rosin, wood rosin, tall oil rosin, distilled rosin, hydrogenated rosin, dimerized rosin, and polymerized rosin; (2) glycerol and pentaerythritol esters of natural and modified rosins, including glycerol esters of pale wood rosin, glycerol esters of hydrogenated rosin, glycerol esters of polymerized rosin, pentaerythritol esters of hydrogenated rosin, and phenolic-modified pentaerythritol esters of rosin; (3) natural terpenes, such as styrene / terpene and alpha methyl styrene / terpene. (4) Polyterpene resins, generally obtained by polymerization of terpene hydrocarbons, such as the bicyclic monoterpene known as pinene, in the presence of a Friedel-Crafts catalyst at moderately low temperatures; hydrogenated polyterpene resins are also included; (5) phenol-modified terpene resins and their hydrogenated derivatives, such as resin products obtained by condensation of bicyclic terpenes and phenols in an acidic medium; (6) aliphatic petroleum hydrocarbon resins obtained by polymerization of monomers consisting primarily of olefins and diolefins; hydrogenated aliphatic petroleum hydrocarbon resins are also included; and (7) cyclic petroleum hydrocarbon resins and their hydrogenated derivatives. Mixtures of two or more of the above tackifying resins may be required in some formulations. Also included are cyclic or acyclic C5 resins and aromatic-modified acyclic or cyclic resins.

[0025] In an embodiment of the present invention, the tackifier is selected from the group consisting of aliphatic and cycloaliphatic hydrocarbon resins and their hydrogenated derivatives, hydrogenated aromatic hydrocarbon resins, aromatic-modified aliphatic or cycloaliphatic resins and their hydrogenated derivatives, polyterpene and styrenated polyterpene resins, and mixtures thereof. In another embodiment of the present invention, the tackifier is selected from the group consisting of C-5 aliphatic hydrocarbon resins, hydrogenated C-5 resins, hydrogenated C-9 resins, hydrogenated DCPD resins, and aromatic-modified DCPD resins.

[0026] In one embodiment of the present invention, the tackifying resin has a Ring and Ball softening point (measured according to ASTM E28) of at least about 40° C., most preferably about 80° C. to 110° C. Even more preferably, the tackifiers used herein have a Ring and Ball softening point of less than 108° C., most preferably less than 105° C.

[0027] One embodiment of the present invention provides a hot melt adhesive composition comprising a tackifying resin in an amount of about 25% to about 65%. Preferably, the tackifying resin is present in an amount of about 30% to about 60% by weight, more preferably about 32% to about 50% by weight, and most preferably about 35% to about 45% by weight.

[0028] The hot melt adhesive composition of the present invention also contains a plasticizer. Plasticizers can be used in the present invention to control the behavior of the adhesive during formulation, application, and end use. Plasticizer components useful in the present invention can be selected from mineral-based oils, petroleum-based oils, liquid resins, liquid elastomers, polybutene, polyisobutylene, phthalate and benzoate plasticizers, and epoxidized soybean oil. Preferably, the plasticizer is selected from the group consisting of mineral oils and liquid polybutenes, more preferably mineral oils having less than 30% aromatic carbon atoms. Plasticizers are generally defined as typically organic compositions that can be added to thermoplastic rubbers and other resins to improve extrudability, flexibility, processability, and stretchability in the finished adhesive. Any material that flows at ambient or application temperatures and is compatible with the compositions of the present invention can be useful. Preferably, the plasticizer has low volatility at temperatures above about 40°C. The most commonly used plasticizers are primarily hydrocarbon oils with low aromatic content and are paraffinic or naphthenic in character. The oil preferably has low volatility, clarity, low color, and negligible odor. The present invention may also include olefin oligomers, low molecular weight polymers, synthetic hydrocarbon oils, vegetable oils and their derivatives, and similar plasticizing oils. Solid plasticizers may also be useful in the present invention. Examples of such plasticizers include 1,4-cyclohexanedimethanol dibenzoate, glyceryl tribenzoate, pentaerythritol tetrabenzoate, and dicyclohexyl phthalate. Petroleum-based oils with suitable naphthenic mineral oils useful in the present invention of the type described herein above are preferred and are commercially available from Nynas under the trade name Nyplast®. Suitable liquid plasticizers include polybutenes, such as the Indopol series materials supplied by Ineos. Blends of plasticizers may also be utilized to tailor end-use performance and final properties, as needed.

[0029] The plasticizer may be used in an amount of about 2% to about 25% by weight, more preferably about 5% to about 20% by weight, even more preferably about 7% to about 18% by weight, and most preferably about 10% to about 16% by weight. Blends of two or more plasticizers may also be used. For example, a blend of a first plasticizer and a second plasticizer different from the first plasticizer may also be utilized. If necessary, about 1% to about 19% by weight of one or more additional plasticizers may be blended with the first plasticizer to achieve the total amounts listed above.

[0030] The hot melt adhesive of the present invention may also contain a stabilizer or antioxidant in an amount of about 0.1% to about 5% by weight. Preferably, about 0.1% to 2% of a stabilizer or antioxidant is incorporated into the composition. Stabilizers effective in the hot melt adhesive composition of the present invention are incorporated to help protect the above-noted polymers, and thus the entire adhesive system, from the effects of thermal and oxidative degradation that typically occur during adhesive manufacturing and application, as well as during normal exposure of the final product to the ambient environment. Among applicable stabilizers are multifunctional phenols, such as hindered phenols and sulfur- and phosphorus-containing phenols. Antioxidants, such as hindered amine phenols, can be characterized as phenolic compounds that also contain bulky groups near their phenolic hydroxyl groups and are preferred. In particular, a tertiary butyl group is generally substituted onto the benzene ring in at least one of the ortho positions relative to the phenolic hydroxyl group. The presence of these sterically bulky substituents in the vicinity of the hydroxyl group serves to retard its stretching frequency and hence its reactivity; thus, such steric hindrance provides stabilizing properties to the phenolic compound. Representative hindered phenols include: 1,3,5-trimethyl-2,4,6-tris(3-5-di-tert-butyl-4-hydroxybenzyl)benzene, pentaerythritol tetrakis-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, n-octadecyl-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4,4'-methylenebis(4-methyl-6-tert-butylphenol), 2,6-di-tert-butylphenol, 6-(4-hydroxyphenoxy)-2,4-bis(n-octylthio-1,3,5-triazine, 2,3,6-tris(4-hydroxy-3,5-di-tert-butyl-phenoxy),3,5-triazine, di-n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 2-(n-octylthio)ethyl-3,5-di-tert-butyl-4-hydroxybenzoate, and Sorbitol hexa-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0031] Polyolefin nucleating agents may also be present in the present invention. Nucleating agents suitable for the present invention are generally a subclass of nucleating agents known as clarifiers, commonly utilized in polyolefin additive packages to promote rapid crystallization. Suitable materials include dibenzylidene sorbitol derivatives, such as Millad 3988 and Millad NX8000 supplied by Milliken and Irgaclear D manufactured by BASF. Other suitable agents include aromatic amides, such as NJ Star NU-100 supplied by New Japan Chemical Company. When included, nucleating agents are generally present in the adhesive composition in an amount of about 0.05% to 5% by weight of the composition. Preferably, about 0.1% to 2.5% by weight, and most preferably about 0.2% to 1.0% by weight, are utilized. Blends of two or more nucleating agents may also be used. For example, a blend of a first nucleating agent and a second nucleating agent different from the first nucleating agent may be utilized. Optionally, about 0.05% to about 5% by weight of one or more additional nucleating agents can be blended with the first nucleating agent. The nucleating agent can be used directly as a powder, as a slurry in a portion of a suitable plasticizer, or as a component in a masterbatch of a suitable polymer masterbatch, such as Milliken NX-10. Nucleating agent packages, such as those described in U.S. Patent Application Publication No. 2015 / 0299526, can also be included to adjust the set-up rate and bonding properties of the hot melt adhesive.

[0032] It should be understood that other optional additives may be incorporated into the adhesive composition of the present invention to modify specific physical properties. These may include, for example, materials such as ultraviolet light (UV) absorbers, waxes, surfactants, inert colorants, titanium dioxide, fluorescent agents, and fillers. Typical fillers include talc, calcium carbonate, clay silica, mica, wollastonite, feldspar, aluminum silicate, alumina, hydrated alumina, glass microspheres, ceramic microspheres, thermoplastic microspheres, baryte, and wood flour, and may be included in amounts up to 60% by weight, preferably 1-50% by weight.

[0033] In one embodiment of the present invention, the hot melt adhesive composition does not contain wax. In embodiments of the present invention in which wax is included, the wax may be included in an amount of up to 20% by weight, preferably 0.1% to 18% by weight. The wax may be selected from the group consisting of petroleum waxes, low molecular weight polyethylene and polypropylene, synthetic waxes, and polyolefin waxes, and mixtures thereof. In a preferred embodiment, the wax is low molecular weight polyethylene having a number average molecular weight of about 400 to about 6,000 g / mol.

[0034] The viscosity of the adhesive material according to the present invention should generally be at a viscosity at an application temperature suitable for processing and application to a substrate. To be processed by standard hot melt adhesive equipment and achieve the desired pattern at the application temperature, and therefore the appropriate bond performance, an adhesive with a relatively low viscosity at low application temperatures is required. Generally, the viscosity is about 35,000 cP or less at 121°C, preferably about 30,000 cP or less at 121°C, even more preferably less than about 25,000 cP at 121°C, and even more preferably less than about 20,000 cP at 121°C, according to ASTM D3236. All viscosities indicated herein are measured according to such modified ASTM standards. Preferably, the viscosity of the composition is at least 1,000 cP, more preferably at least 5,000 cP, even more preferably at least about 7,500 cP, and most preferably at least about 15,000 cP at 121°C. When lower and upper limits for some of the property values ​​are recited herein, the present invention includes ranges between and including any of the lower limits and any of the upper limits. Thus, the viscosity can be from 1,000 cP to 35,000 cP and from 5,000 cP to 20,000 cP at 121° C. In other embodiments, the viscosity of the composition is between any of the ranges contemplated herein at various typically used application temperatures between 121° C. and 149° C., such as 121° C., 127° C., 135° C., and 149° C.

[0035] In an embodiment of the invention, the hot melt adhesive composition comprises, consists essentially of, or consists of a first polymer, a second polymer, a tackifying resin, and a plasticizer. In an embodiment of the invention, the composition comprises the first and second polymers and no other polymers.

[0036] The hot melt adhesive composition of the present invention can be compounded using any technique known in the art. A typical example of a mixing procedure involves placing all ingredients into a jacketed mixing vessel equipped with a rotor, and then raising the temperature of the mixture to a range of 120°C to 230°C to melt the contents. It should be understood that the exact temperature used in this step will depend on the melting points of the specific ingredients. The ingredients are introduced into the vessel under agitation, either individually or in a specific combination, and mixing is continued until a stable, homogeneous mixture is formed.

[0037] In an embodiment of the present invention, the adhesive is prepared at approximately 180°C using a conventional overhead mixer. First, the plasticizer, tackifier, and any antioxidants are heated to the desired temperature under an inert blanket, and stirring is initiated to achieve uniformity. While the order of polymer addition does not appear to affect the final result, in some embodiments, the first polymer component is added first. Once all polymers have dissolved and the mixture appears uniform, the second polymer is added. Mixing is continued with heating until the mixture is again uniform and the second polymer has dissolved. Other conventional methods can also be used to prepare the hot melt adhesives of the present invention. For example, methods utilizing static mixing, single-screw extrusion, twin-screw extrusion, and kneading can be used. The hot melt adhesive is then cooled to room temperature and formed into chubs, on which a protective skin is formed, or into pellets for transport and use.

[0038] The resulting hot melt adhesive can then be applied to a substrate using a variety of coating techniques. Examples include hot melt slot die coating, hot melt wheel coating, hot melt roller coating, melt blown coating, and slot, spiral spray, and wrapping spray methods, such as those used to attach elastic strands. Spray techniques are numerous and can be performed with or without the assistance of compressed air, which will create the adhesive spray pattern. The hot melt adhesive material is generally pumped through a hose to the final coating spot on the substrate. Any application temperature above the softening point of the adhesive formulation is suitable.

[0039] The hot melt adhesive composition of the present invention can be used in many applications, such as disposable nonwoven hygiene articles, paper processing, flexible packaging, wood processing, carton and case sealing, labeling, and other assembly applications. Particularly preferred applications include diaper and adult incontinence brief elastic attachment, disposable diaper and feminine sanitary napkin construction, diaper and napkin core stabilization, diaper backsheet lamination, industrial filter material processing, surgical gown and surgical drape assembly. The adhesive of the present invention has been found to be particularly useful as a construction adhesive in hygiene articles such as diapers. Construction adhesives are typically used to bond nonwoven layers to polyethylene films.

[0040] The adhesives of the present invention can be used in any application involving a variety of substrate materials. Examples include nonwoven materials and polymeric films. Any substrate material and any substrate form can be used in any possible combination with the adhesive functioning as a single substrate folded onto itself or to bond two or more substrates together. The substrate can be in multiple forms, such as fibers, films, threads, strips, ribbons, tapes, coatings, foils, sheets, and bands. The substrate can be of any known composition, such as polyolefins, polyacrylics, polyesters, polyvinyl chloride, polystyrene, wood, cellulosic materials such as cardboard, or paper. The mechanical behavior of the bulk substrate can be rigid, plastic, or elastomeric. The above list is not intended to be limiting or comprehensive, but is provided merely as a general example.

[0041] In an embodiment of the present invention, a method for making a laminate includes the steps of: (1) applying a hot melt adhesive composition of the present invention in a molten state to a primary substrate; and (2) conforming a secondary substrate to the primary substrate by contacting the secondary substrate with the adhesive composition. Upon cooling, the adhesive bonds the primary substrate to the secondary substrate. In embodiments where the adhesive is suitable for use as a construction adhesive, the primary substrate may be a polyolefin film such as polyethylene, and the secondary substrate may be a nonwoven material or layer.

[0042] In another embodiment of the present invention, the adhesive is applied to the first substrate using a direct contact method of hot melt application, such as a slot or V-slot applicator head. Alternatively, the adhesive can be applied to the first substrate using a non-contact method of hot melt application, such as a spray applicator.

[0043] According to an embodiment of the present invention, the hot melt adhesive composition comprises: (a) about 35% to about 55% by weight, preferably about 40% to about 50% by weight, and most preferably about 42% to about 47% by weight of a first polymer comprising a monomodal copolymer of propylene and ethylene and having a weight average molecular weight of about 5,000 to 60,000 Daltons; (b) about 0.5% to about 7% by weight, preferably about 1% to 5% by weight, and most preferably about 1% to about 4% by weight of a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 Daltons; and (c) about 30% to about 60% by weight, preferably about 40% to about 50% by weight of a propylene copolymer. and (d) about 5% to about 20% by weight, preferably about 7% to about 18% by weight, and most preferably about 10% to about 16% by weight of a plasticizer, wherein the weight ratio of the first polymer to the second polymer is about 200:1 to 9:1, preferably about 75:1 to about 10:1, and most preferably about 50:1 to about 15:1, and the viscosity of the composition is about 30,000 cP or less at 121°C, preferably less than about 25,000 cP at 121°C, and more preferably less than about 20,000 cP at 121°C. According to another embodiment of the present invention, the combined weight of the first and second polymers comprises from about 31% to about 72%, preferably from about 36% to about 55%, and most preferably from about 40% to about 50%, based on the total weight of the hot melt adhesive composition.

[0044] According to another embodiment of the present invention, the hot melt adhesive composition comprises (a) about 30% by weight to about 72% by weight of a monomodal copolymer of propylene and ethylene, and having a weight average molecular weight of about 20,000 to about 55,000 daltons, a heat of fusion of about 5 to about 35 J / g, a polydispersity index of about 1.5 to about 6, an ethylene content of about 5% by weight to about 25% by weight, a melting temperature of about 70°C to about 130°C, and a glass transition temperature of about -45°C to about -5°C. (b) from about 0.1% to about 8% of a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 Daltons; (c) from about 25% to about 65% by weight of a tackifying resin having a Ring and Ball softening point of at most 115°C; and (d) from about 2% to about 25% by weight of a plasticizer, wherein the weight ratio of the first polymer to the second polymer is from about 500:1 to 9:1, and the viscosity of the composition (as measured by ASTM D3236) is about 35,000 cP or less at 121°C.

[0045] According to an embodiment of the present invention, a hot melt adhesive composition comprises: (a) a first polymer comprising a monomodal copolymer of propylene and ethylene and having a weight average molecular weight of about 5,000 to 60,000 daltons; (b) a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 daltons; (c) a tackifying resin having a Ring and Ball softening point of at most 115°C; and (d) a plasticizer, wherein the viscosity of the composition is about 35,000 cP or less at 121°C, and the first polymer, the second polymer, The tackifying resin and plasticizer are present in amounts effective to provide a hot melt adhesive composition having: (1) an initial peel force of at least 150 grams force and at least 250 grams force after aging at 54.5°C when applied at a 2 gsm add-on between a polyethylene film and a nonwoven layer; (2) an initial peel force of at least 100 grams force when applied at a 1 gsm add-on between a polyethylene film and a nonwoven layer; and (3) a shear value of at least 50 minutes at 37.8°C when applied between two nonwoven layers and using a 250 gram weight. While it is believed that the adhesives of the present invention are capable of achieving such peel and shear performance with a variety of substrates and add-on levels, embodiments of the present invention use specific substrates and conditions as demonstrated in the examples below.

[0046] Aspects of the invention 1. (a) a first polymer comprising about 30% to about 72% by weight of a monomodal copolymer of propylene and ethylene and having a weight average molecular weight of about 5,000 to 60,000 daltons; (b) about 0.1% to about 8% of a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 daltons; (c) about 25% to about 65% by weight of a tackifying resin having a Ring and Ball softening point of up to 115°C; (d) about 2% by weight to about 25% by weight of a plasticizer; wherein the weight ratio of the first polymer to the second polymer is from about 500:1 to 9:1, and the viscosity of the composition is about 35,000 cP or less at 121°C.

[0047] 2. (a) a first polymer comprising a monomodal copolymer of propylene and ethylene and having a weight average molecular weight of about 5,000 to 60,000 daltons; (b) a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 daltons; (c) a tackifying resin having a ring and ball softening point of at most 115°C; (d) plasticizers and wherein the viscosity of the composition is about 35,000 cP or less at 121°C, and the first polymer, second polymer, tackifying resin, and plasticizer are present in amounts effective to provide a hot melt adhesive composition having: (1) an initial peel force of at least 150 grams force when applied at a 2 gsm add-on between a polyethylene film and a nonwoven layer and at least 250 grams force after aging at 54.5°C; (2) an initial peel force of at least 100 grams force when applied at a 1 gsm add-on between a polyethylene film and a nonwoven layer; and (3) a shear value of at least 50 minutes at 37.8°C when applied between two nonwoven layers and using a 250 gram weight.

[0048] 3. the first polymer is present in an amount of from about 35% to about 55% by weight, preferably from about 40% to about 50% by weight, and most preferably from about 42% to about 47% by weight; the second polymer is present in an amount of about 0.5% to about 7% by weight, preferably about 1% to 5% by weight, and most preferably about 1% to about 4% by weight; the tackifying resin is present in an amount of from about 30% to about 60% by weight, preferably from about 32% to about 50% by weight, and most preferably from about 35% to about 45% by weight; the plasticizer is present in an amount of from about 5% to about 20% by weight, preferably from about 7% to about 18% by weight, and most preferably from about 10% to about 16% by weight; the weight ratio of the first polymer to the second polymer is from about 200:1 to about 9:1, preferably from about 75:1 to about 10:1, and most preferably from about 50:1 to about 15:1; and 3. The composition of any of embodiments 1 or 2, wherein the viscosity of the composition is no greater than about 30,000 cP at 121°C, preferably less than about 25,000 cP at 121°C, and more preferably less than about 20,000 cP at 121°C.

[0049] 4. The first polymer has a heat of fusion of about 5 to about 35 J / g, preferably about 10 to about 29 J / g, more preferably about 15 to about 25 J / g, and most preferably about 18 to about 22 J / g; and The composition of any of Aspects 1-3, wherein the second polymer has a heat of fusion of from about 2.5 to about 25 J / g, preferably from about 3 to about 15 J / g, more preferably from about 3.5 to about 10 J / g, and most preferably from about 6 to about 9 J / g.

[0050] 5. The first polymer has a polydispersity index of from about 1.5 to about 6, preferably from about 1.8 to about 5, more preferably from about 2 to about 3, and most preferably from about 2.2 to about 2.8; and The composition of any of embodiments 1-4, wherein the second polymer has a polydispersity index of from about 1.5 to about 6, preferably from about 1.8 to about 5, more preferably from about 2 to about 3, and most preferably from about 2.2 to about 2.8.

[0051] 6. The weight average molecular weight of the first polymer is about 20,000 to about 55,000 daltons, preferably about 30,000 to about 52,000 daltons, more preferably about 35,000 to about 50,000 daltons, and most preferably about 40,000 to about 48,000 daltons; and The composition of any of Aspects 1 to 5, wherein the weight average molecular weight of the second polymer is about 100,000 to 250,000 daltons, preferably about 100,000 to about 200,000 daltons, more preferably about 100,000 to about 150,000 daltons, and most preferably about 105,000 to about 125,000 daltons.

[0052] 7. The first polymer has an ethylene content of from about 5% to about 25%, preferably from about 7% to about 20%, more preferably from about 9% to about 17%, and most preferably from about 10% to about 15%; and The composition of any of embodiments 1-6, wherein the second polymer has an ethylene content of from about 5% to about 25%, preferably from about 7% to about 20%, more preferably from about 9% to about 17%, and most preferably from about 10% to about 15%.

[0053] 8. The first polymer has a melting temperature of about 70°C to about 130°C, preferably about 75°C to about 125°C, more preferably about 85°C to about 115°C, and most preferably about 90°C to about 110°C; and The composition of any of Aspects 1 to 7, wherein the second polymer has a melting temperature of about 35°C to about 100°C, preferably about 40°C to about 90°C, more preferably about 50°C to about 80°C, and most preferably about 55°C to about 75°C.

[0054] 9. The first polymer has a glass transition temperature of about -45°C to about -5°C, preferably about -35°C to about -15°C, more preferably about -32°C to about -20°C, and most preferably about -30°C to about -22°C; and The composition of any of Aspects 1-8, wherein the second polymer has a glass transition temperature of about -45°C to about -5°C, preferably about -35°C to -15°C, more preferably about -32°C to -20°C, and most preferably about -30°C to -22°C.

[0055] 10. The composition of any of the preceding aspects, wherein the tackifier is selected from the group consisting of aliphatic and alicyclic hydrocarbon resins and their hydrogenated derivatives, hydrogenated aromatic hydrocarbon resins, aromatic-modified aliphatic or alicyclic resins and their hydrogenated derivatives, polyterpene and styrenated polyterpene resins, and mixtures thereof.

[0056] 11. The composition of any of the preceding aspects, wherein the plasticizer is selected from the group consisting of mineral oil and liquid polybutene.

[0057] 12. The composition of any of aspects 1-11, further comprising a stabilizer or antioxidant.

[0058] 13. The composition of any of aspects 1-12, further comprising a wax.

[0059] 14. The composition of embodiment 13, wherein the wax is present in an amount of about 0.1% to about 20% by weight.

[0060] 15. The composition of any of embodiments 1-14, wherein the combined weight of the first and second polymers comprises from about 31% to about 72%, preferably from about 36% to about 55%, and most preferably from about 40% to about 50%, based on the total weight of the hot melt adhesive composition.

[0061] 16. The first polymer has a heat of fusion of about 5 to about 35 J / g; the first polymer has a polydispersity index of from about 1.5 to about 6; the first polymer has a weight average molecular weight of about 20,000 to about 55,000 daltons; the first polymer has an ethylene content of about 5% to about 25% by weight; the first polymer has a melting temperature of about 70°C to about 130°C; and 16. The composition of any of embodiments 1-15, wherein the first polymer has a glass transition temperature of about -45°C to about -5°C.

[0062] 17. Applying the hot melt adhesive composition of any of Aspects 1-16 in a molten state to a primary substrate; conforming the secondary substrate to the primary substrate by contacting the secondary substrate with an adhesive composition; A method for producing a laminate, comprising:

[0063] 18. The method of embodiment 17, wherein the primary substrate is a polyethylene film.

[0064] 19. The method of any of aspects 17 or 18, wherein the secondary substrate is a nonwoven layer.

[0065] 20. A laminate produced by the method of any one of aspects 17 to 19. [Example]

[0066] The following examples illustrate the invention without limiting it.

[0067] Viscosity was measured according to ASTM D3236 at 121° C. The spindle speed was adjusted and the percent torque was between 45% and 90%.

[0068] Ring and Ball softening points were determined using an automated Herzog unit according to the method set forth in ASTM E-28.

[0069] raw materials: Calsol 5550 is a naphthenic process oil available from Calumet Specialty Products. Eastotac H-100W is a hydrogenated hydrocarbon resin with a ring and ball softening point of 100°C available from Eastman Chemical Company. Escorez 5615 is a hydrogenated aromatic modified cycloaliphatic hydrocarbon resin with a ring and ball softening point of 118°C available from ExxonMobil Corporation. Irganox 1010 is an antioxidant that is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), a hindered phenol, available from BASF SE. Vistamaxx 8380, available from Exxonmobil Chemical Company, Houston, TX, is a low molecular weight, low viscosity metallocene-catalyzed random propylene-ethylene copolymer with about 12 wt% ethylene comonomer and a weight average molecular weight (Mw) of about 43,000 g / mol, a DSC melting point of about 100°C, and a DSC enthalpy of melting of about 20 J / g. Vistamaxx 6502, available from Exxonmobil Chemical Company, Houston, TX, is an essentially amorphous copolymer containing about 13% by weight ethylene comonomer and having a weight average molecular weight (Mw) of about 119,000 g / mol, a DSC melting point of about 64°C, and a DSC melting enthalpy of about 9 J / g.

[0070] The adhesive was formulated by melting the oil, tackifier, and antioxidant at approximately 180°C under a nitrogen blanket. The lower molecular weight polymer (Vistamaxx 8380) was then added. Once the formulation had returned to temperature prior to polymer addition and appeared homogeneous, the second, higher molecular weight polymer was added. The formulation continued to be mixed until it was completely homogeneous and no polymer beads were visible.

[0071] The adhesive was used to form bilaminates consisting of a primary substrate with an adhesive layer to which a secondary substrate was subsequently bonded. Typically, these laminates were produced using a Nordson Signature nozzle to apply 2 gsm adhesive at a speed of 900 ft / min and an open time (the time the adhesive contacts the secondary layer) of 0.25 seconds. The application temperature was 149°C and 40 psi compression. While many types of substrates can be used as either the primary and / or secondary components, the primary substrate used in the following examples for peel performance testing was DH284, a 24 gsm non-breathable polyethylene film commercially available from Clopay Plastics Products. The secondary substrate used for peel performance testing was a 15 gsm spunbond nonwoven available from First Quality Enterprises. Shear tests were performed on bilaminates in which the primary and secondary substrates were 50 gsm meltblown nonwovens from Berry Global.

[0072] To determine adhesive peel performance, laminates were either tested "initial" (meaning they were aged at room temperature for approximately 24 hours) or subjected to various aging times, such as 1, 2, or 4 weeks at 54.5°C. The laminates were then pulled apart in an Instron tensile tester at a rate of 12 inches per minute in a 180-degree "T" peel in an air-conditioned room maintained at 23.9°C and 50% relative humidity. Peel force was measured in grams of force, and peel values ​​were calculated by determining the average peel strength after removing the first and last 5 percent of the sample length to reduce variability from the start and stop of the test. The test was performed using add-on levels of 1 or 2 grams per square meter, as shown in the results below.

[0073] To determine shear performance, the adhesive is applied at a 15 gsm add-on level in a 1 inch slot pattern. Laminates were tested for shear the day after production. To perform the shear test, 1 inch strips of laminate are cut. The primary substrate is stably suspended in a 37.8°C oven while a 250g weight is attached to the secondary substrate. When the adhesive adheres and fails, the weight is lowered and the timer is stopped, giving the suspension time in minutes.

[0074] The weight percentages of the various components used are shown below. As shown, the formulation of Example 1 (EX1) uses a tackifier with a Ring and Ball softening point of 100°C, while the tackifier used in Comparative Example 2 (CE2) has a Ring and Ball softening point of 118°C. The ratio of low molecular weight polymer to high molecular weight polymer in both cases is about 22.2:1. In Comparative Example 3 (CE3), no high molecular weight polymer was used.

[0075] [Table 1]

[0076] In some applications, a suitable target peel performance at a 2 gsm add-on may be 150 gf when initially tested and 250 gf after the laminate is aged at 54.5°C. The formulation of Example 1 meets this peel criterion, but when a higher softening point tackifier is used (as in Comparative Example 2), the aged peel performance decreases significantly. Inventive Example 1 also exhibits desirable peel performance (e.g., greater than 100 gf) at lower add-on weights (i.e., 1 gsm). A formulation without a high molecular weight polymer (CE3) has good initial peel performance, but after aging, its peel performance decreases to less than 100 gf, and in some applications it does not provide adequate shear strength.

[0077] Figure 1 shows the peel performance after 1 week aging versus shear strength for EX1, CE2, and CE3, where the circle size represents the standard deviation. As shown, the formulations of the present invention performed better than CE3 in the shear test and better than CE2 in peel strength.

[0078] Figure 2 shows the peel performance of EX1 at three different application temperatures, i.e., 127°C, 135°C, and 149°C, both initially and after 1, 2, and 4 weeks of environmental aging. The EX1 formulation was sprayable at all application temperatures and had a viscosity at 121°C (15,120 cP) low enough to be applied as a construct adhesive using many commercially available application systems. Figure 2 demonstrates that the present invention provides formulations with consistent peel performance at standard application temperatures (149°C) and at lower application temperatures (135°C and 127°C).

[0079] Figure 3 shows the peel performance after one week of aging versus shear strength for EX1 and two commercially available formulations. H9564 is a polyolefin-based construction adhesive commercially available from Bostik. H4384 is a styrene-block-copolymer construction adhesive commercially available from Bostik. As shown, the formulation of the present invention provides significantly better shear performance than either of these formulations and better peel performance than H9564.

[0080] When a range of values ​​is provided, it is understood that each intervening value between the upper and lower limits of that range and any other stated or intervening value within that stated range, and any combination or subcombination of intervening values, is included within the recited range of values. In addition, the invention includes a range of a component that is the lower limit of a first range and the upper limit of a second range of that component.

[0081] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All publications and patents specifically cited herein are incorporated by reference in their entirety for all purposes, including the description and disclosure of chemicals, instruments, statistical analyses and methodologies reported in the publications that might be used in connection with the present invention. All references cited herein are considered to be indicative of the level of skill of those skilled in the art. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such disclosure by virtue of prior invention.

[0082] Although illustrated and described herein with reference to specific embodiments, the invention is not nevertheless intended to be limited to the details shown. Rather, various changes in the details may be made within the realm and range of equivalents of the claims and without departing from the spirit of the invention.

Claims

1. (a) a first polymer comprising 42% to 47% by weight of a monomodal copolymer of propylene and ethylene and having a weight average molecular weight of 5,000 to 60,000 Daltons; (b) 1% to 4% by weight of a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 Daltons; (c) 35% to 45% by weight of a tackifying resin having a ring and ball softening point of up to 115°C; (d) 10% to 16% by weight of a plasticizer; 1. A hot melt adhesive composition comprising: the weight ratio of the first polymer to the second polymer is from 47:1 to 42:4, and the viscosity of the composition is less than 20,000 cP at 121°C; the first polymer has a heat of fusion of 18 to 22 J / g; and The hot melt adhesive composition wherein the second polymer has a heat of fusion of 6 to 9 J / g.

2. the first polymer has a polydispersity index of 2.2 to 2.8; and The composition of claim 1, wherein the second polymer has a polydispersity index of 2.2 to 2.

8.

3. the weight average molecular weight of the first polymer is 40,000 to 48,000 daltons; and The composition of claim 1, wherein the weight average molecular weight of the second polymer is from 105,000 to 125,000 Daltons.

4. the first polymer having 10% to 15% by weight of ethylene based on the weight of the first polymer; and 10. The composition of claim 1, wherein the second polymer has from 10% to 15% by weight of ethylene, based on the weight of the second polymer.

5. the first polymer has a melting temperature of 90°C to 110°C; and The composition of claim 1, wherein the second polymer has a melting temperature of from 55°C to 75°C.

6. the first polymer has a glass transition temperature of from −30° C. to −22° C.; and The composition of claim 1, wherein the second polymer has a glass transition temperature of from -30°C to -22°C.

7. The tackifier resin is (a) an aliphatic or alicyclic hydrocarbon resin, or a hydrogenated derivative thereof; (b) hydrogenated aromatic hydrocarbon resins; (c) aromatic modified aliphatic or cycloaliphatic resins, or hydrogenated derivatives thereof; (d) a polyterpene or styrenated polyterpene resin, or (e) a mixture of compounds (a) to (d) 10. The composition of claim 1, selected from the group consisting of:

8. 10. The composition of claim 1, wherein the plasticizer is selected from the group consisting of mineral oil and liquid polybutene.

9. The composition of claim 1 further comprising a stabilizer or antioxidant.

10. The composition of claim 1 further comprising a wax.

11. The composition of claim 10, wherein the wax is present in an amount of from 0.1% to 20% by weight.

12. 10. The composition of claim 1, wherein the combined weight of the first and second polymers comprises 43% to 50% by weight, based on the total weight of the hot melt adhesive composition.

13. the first polymer has a polydispersity index of 1.5 to 6; the weight average molecular weight of the first polymer is 20,000 to 55,000 daltons; the first polymer having 5% to 25% by weight ethylene based on the weight of the first polymer; the first polymer has a melting temperature of 70°C to 130°C; and The composition of claim 1, wherein the first polymer has a glass transition temperature of from -45°C to -5°C.

14. applying the hot melt adhesive composition of any one of claims 1 to 13 in a molten state to a primary substrate; conforming a secondary substrate to the primary substrate by contacting the secondary substrate with the adhesive composition; A method for producing a laminate, comprising:

15. The method of claim 14, wherein the primary substrate is a polyethylene film.

16. The method of claim 15 , wherein the secondary substrate is a nonwoven layer.

17. (a) a first polymer comprising a monomodal copolymer of propylene and ethylene and having a weight average molecular weight of 5,000 to 60,000 daltons; (b) a second polymer comprising a copolymer of propylene and ethylene and having a weight average molecular weight of at least 100,000 Daltons; (c) a tackifying resin having a ring and ball softening point of up to 115°C; (d) a plasticizer; 1. A hot melt adhesive composition comprising: a viscosity of the composition is 35,000 cP or less at 121°C; and the first polymer, the second polymer, the tackifying resin, and the plasticizer are (1) a peel force of at least 1.47 N (150 gf) initially and at least 2.45 N (250 gf) after aging at 54.5°C when the hot melt adhesive composition is applied between a polyethylene film and a nonwoven layer at an add-on level of 2 grams per square meter (2 gsm add-on); (2) an initial peel force of at least 0.98 N (100 gf) when the hot melt adhesive composition is applied between a polyethylene film and a nonwoven layer at an add-on level of 1 gram per square meter (1 gsm add-on); and (3) A hot melt adhesive composition present in an amount effective to provide a hot melt adhesive composition having a shear value of at least 50 minutes at 37.8°C when applied between two nonwoven layers and when cutting a 1 inch (2.54 centimeter) strip of the laminate using a 250 gram weight.

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