Hot melt adhesive composition containing modified styrene block copolymer and article containing the same

Abstract

The present invention relates to a hot-melt adhesive composition for disposable absorbent articles, comprising 5% to 40% by mass of unmodified styrene block copolymer, 0.5% to 30% by mass of modified styrene block copolymer, 30% to 65% by mass of a tackifier, and 10% to 45% by mass of a plasticizer, characterized in that the hot-melt adhesive composition contains less than 5% by mass of wax.

Description

[Background technology]

[0001] Hot melt adhesive compositions are often used to join substrates together to maintain a fixed relationship between two substrates, or to contribute to the integrity and functionality of the finished article. In the field of industrial adhesives, hot melt adhesive compositions are generally used to join or contribute to the integrity and functionality of a wide variety of articles, including packaging materials (e.g., cases and cartons), and disposable absorbent articles containing nonwoven fabric substrates, such as adult incontinence products, disposable diapers, sanitary napkins, bed pads, puppy pads, medical bandages, etc.

[0002] Multiple hot-melt adhesive compositions may be used in the manufacture of disposable absorbent articles. For example, in the manufacture of disposable diapers, hot-melt adhesive compositions are used as structural adhesives (e.g., to bond the backsheet to the nonwoven fabric and optionally to the absorbent pad), as elastic attachment adhesives (e.g., to bond elastic material to the backsheet in the leg or waist area), for core stabilization (e.g., to increase the strength of the absorbent core by applying the hot-melt adhesive composition to the absorbent core), for positioning, i.e., for aligning the article to the base material (e.g., underwear) in disposable absorbent (e.g., feminine hygiene) articles, and as elastic materials to impart stretchability to disposable absorbent articles.

[0003] For hot-melt adhesive compositions to function well in adhesive applications such as disposable absorbent articles and skin-adhesive applications, improved adhesion to various substrates under various conditions is required. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2014 / 324006 [Patent Document 2] International Publication No. 2014 / 051160 [Overview of the project]

[0005] In one aspect, the present invention is characterized by a hot melt adhesive composition comprising 5% to 40% by mass of unmodified styrene block copolymer, 0.5% to 15% by mass of modified styrene block copolymer, 30% to 65% by mass of a tackifier, and 10% to 45% by mass of a plasticizer, wherein the hot melt adhesive composition comprises less than 5% by mass of wax. In another aspect, the present invention is characterized by a hot melt adhesive composition comprising 5% to 40% by mass of unmodified styrene block copolymer, 0.5% to 30% by mass of modified styrene block copolymer, 30% to 65% by mass of a tackifier, and 10% to 45% by mass of a plasticizer, wherein the hot melt adhesive composition comprises less than 5% by mass of wax.

[0006] In one embodiment, the present invention is characterized by a disposable absorbent article comprising a hot-melt adhesive composition. In another embodiment, the hot-melt adhesive composition comprises less than 4% by mass of wax, or rather 0.5% to less than 5% by mass of modified wax.

[0007] In another embodiment, the modified styrene block copolymer is a styrene block copolymer modified with an organic acid or an anhydride selected from the group consisting of poly(styrene-b-(ethylene-co-butylene)-b-styrene), poly(styrene-b-(ethylene-alt-propylene)-b-styrene), and poly(styrene-b-isobutylene-b-styrene). In one different embodiment, the combined average styrene content of the unmodified styrene block copolymer and the modified styrene block copolymer is 20% to 45% by mass. In another embodiment, the combined average styrene content of the unmodified styrene block copolymer and the modified styrene block copolymer is 25% to 45% by mass. In one different embodiment, the combined average diblock content of the unmodified styrene block copolymer and the modified styrene block copolymer is 0% to 30% by mass. In one embodiment, the combined average diblock content of the unmodified styrene block copolymer and the modified styrene block copolymer is 10% to 25% by mass.

[0008] In one embodiment, the tackifier has an average R&B softening point of 100°C to 130°C. In another embodiment, the tackifier is a hydrogenated hydrocarbon resin selected from the group consisting of hydrocarbon resins, aromatically modified hydrocarbon resins, aromatic hydrocarbon resins, and combinations thereof. In a different embodiment, the plasticizer is selected from the group consisting of naphthenic oils, paraffinic oils, polyisobutylene, polybutene, and combinations thereof.

[0009] In one embodiment, the hot melt composition has a Brookfield viscosity of 15,000 cP or less at 149°C. In another embodiment, the hot melt composition has a Brookfield viscosity of 15,000 cP or less at 121°C.

[0010] In another embodiment, the present invention is characterized by a hot-melt pressure-sensitive adhesive composition comprising 5% to 25% by mass of an unmodified styrene block copolymer, 1% to 10% by mass of a modified styrene block copolymer, 40% to 60% by mass of a hydrogenated hydrocarbon tackifier, and 15% to 45% by mass of an oil or rather a naphthenic oil, wherein the hot-melt pressure-sensitive adhesive composition comprises less than 5% by mass of wax.

[0011] In one embodiment, the unmodified styrene block copolymer and the modified styrene block copolymer have an average styrene content of 25% to 45% by mass or rather 15% to 30% by mass, and an average diblock content of 10% to 25% by mass.

[0012] In another embodiment, the present invention features a disposable absorbent article comprising a hot-melt pressure-sensitive adhesive composition. In one embodiment, the present invention features an article selected from the group consisting of medical tapes, bandages, wearable devices, athletic tapes, kinesiology tapes, and wound dressings comprising a hot-melt adhesive composition.

[0013] In one different embodiment, the modified styrene block copolymer is a styrene block copolymer modified with an organic acid or an anhydride, selected from the group consisting of poly(styrene-b-(ethylene-co-butylene)-b-styrene), poly(styrene-b-(ethylene-alt-propylene)-b-styrene), and poly(styrene-b-isobutylene-b-styrene). In one embodiment, the hot melt pressure-sensitive adhesive composition comprises at least one styrene block copolymer having a diblock content. In another embodiment, the peel of the hot melt pressure-sensitive adhesive does not decrease when tested according to the Humidity Incubated Peel Test Method. In another embodiment, the hot melt pressure-sensitive adhesive composition has a 180-degree peel of at least 5 N / cm to both stainless steel and HDPE when tested according to the 180-degree peel adhesion test method for high-density polyethylene (HDPE) or stainless steel. In one different embodiment, the modified styrene block copolymer, styrene block copolymer, tackifier, and plasticizer constitute at least 90% by mass of the hot melt adhesive composition.

[0014] In one embodiment, the modified styrene block copolymer has a radial structure including 3 to 10 arms, a hydrogenated mid-block, and a styrene content of 6% to 15% by mass. In another embodiment, the modified styrene block copolymer has a radial structure including 3 to 10 arms, a hydrogenated mid-block, and a styrene content of 25% to 45% by mass.

[0015] In another embodiment, the present invention is characterized by an absorbent article comprising a top sheet, a back sheet, optionally an absorbent core disposed between the top sheet and the back sheet, a surface facing clothing, and a hot melt pressure-sensitive adhesive composition disposed on the surface facing clothing of the absorbent article, the hot melt pressure-sensitive adhesive composition comprising a styrene block copolymer, a modified styrene block copolymer, a tackifier, and a plasticizer.

[0016] The inventors have discovered that incorporating a modified styrene block copolymer into a composition containing a limited amount of wax yields a hot-melt adhesive composition with improved adhesion to various substrates under various conditions.

[0017] The composition of the present invention is particularly useful as a positioning adhesive. Positioning adhesives are used to bond disposable absorbent articles to various materials, including, for example, fabrics used in underwear. In one embodiment, this use presents the challenge that the hot-melt adhesive composition needs to bond to various different fabrics, including cotton, microfiber, etc., and to various different environments, including high-humidity environments such as when the user is exercising. On the other hand, when the user is disposing of the disposable absorbent article, it needs to be easily removed without tearing. Other features and advantages will become apparent from the following description of preferred embodiments and the claims. [Modes for carrying out the invention]

[0018] The composition of the present invention is a hot-melt adhesive composition, or rather a hot-melt pressure-sensitive adhesive composition. The hot-melt pressure-sensitive adhesive composition is tacky at room temperature.

[0019] The present invention relates to a hot melt adhesive composition comprising 5% to 40% by mass of unmodified styrene block copolymer, 0.5% to 15% by mass of modified styrene block copolymer, 30% to 65% by mass of a tackifier, and 10% to 45% by mass of a plasticizer, characterized in that it comprises less than 5% by mass of wax.

[0020] The present invention relates to a hot melt adhesive composition comprising 5% to 40% by mass of unmodified styrene block copolymer, 0.5% to 30% by mass of modified styrene block copolymer, 30% to 65% by mass of a tackifier, and 10% to 45% by mass of a plasticizer, characterized in that it comprises less than 5% by mass of wax.

[0021] The present invention also features a hot-melt adhesive composition comprising 10% to 40% by mass of an unmodified styrene block copolymer, 0.5% to 15% by mass of a modified styrene block copolymer, 30% to 65% by mass of a tackifier, and 10% to 45% by mass of a plasticizer, and containing less than 0% to 4% by mass of wax.

[0022] The present invention also features a hot-melt adhesive composition comprising 10% to 40% by mass of an unmodified styrene block copolymer, 0.5% to 30% by mass of a modified styrene block copolymer, 30% to 65% by mass of a tackifier, and 10% to 45% by mass of a plasticizer, and containing less than 0% to 4% by mass of wax.

[0023] The present invention further features a hot-melt pressure-sensitive adhesive composition comprising 5% to 25% by mass of an unmodified styrene block copolymer, 1% to 10% by mass of a modified styrene block copolymer, 40% to 60% by mass of a hydrogenated hydrocarbon tackifier, and 25% to 43% by mass of an oil, and containing less than 5% by mass of wax.

[0024] The present invention also features a disposable absorbent article comprising a topsheet, a backsheet, an absorbent core optionally disposed between the topsheet and the backsheet, a surface facing the clothing; and a hot-melt pressure-sensitive adhesive composition disposed on the surface of the absorbent article facing the clothing, the hot-melt pressure-sensitive adhesive composition containing a styrene block copolymer, a modified styrene block copolymer, a tackifier, and a plasticizer.

[0025] The total amount of the unmodified styrene block copolymer, the modified styrene block copolymer, the tackifier, and the plasticizer may constitute at least 80% by mass, at least 85% by mass, at least 90% by mass, or rather at least 95% by mass of the hot-melt adhesive composition.

[0026] The hot melt adhesive composition may have a Brookfield viscosity of 20,000 centipoise (cP) or less, 15,000 cP or less, 10,000 cP or less, 100 cP to 20,000 cP, or rather 100 cP to 15,000 cP at 149°C, or rather 121°C.

[0027] If the hot-melt adhesive composition is a pressure-sensitive adhesive composition, it may exhibit peeling that does not decrease over time even under high humidity conditions when tested according to the wet temperature peel test method.

[0028] Hot-melt adhesive compositions provide strong adhesion to a wide variety of substrates. When a hot-melt adhesive composition is a pressure-sensitive adhesive composition, it can produce a 180-degree peel of at least 3 N / cm, or rather at least 5 N / cm, to both stainless steel and high-density polyethylene (HDPE) or stainless steel when tested according to the 180-degree peel adhesion test method.

[0029] Styrene block copolymer The hot melt adhesive composition contains unmodified styrene block copolymer (SBC) and modified SBC.

[0030] Unmodified and modified SBCs may contain multiple grades of SBC. When multiple SBCs are present, the styrene content, diblock content, and melt flow rate range specified below are the mass average of the various grades present, including the unmodified and modified grades.

[0031] As an example, consider a hot-melt adhesive composition containing two types of SBCs, A and B. Polymer A is present at 25% by mass (wA) with a styrene content of 15% (sA), and polymer B is present at 25% by mass (wB) with a styrene content of 20% by mass (sB). The average styrene content of the styrene block copolymer is calculated by the following method: wA / (wA+wB) * sA+wB / (wA+wB) *sB=0.5(15)+0.5(20)=17.5% by mass

[0032] SBC may have an average styrene content of 15% to 45% by mass, 20% to 45% by mass, 25% to 45% by mass, 27% to 43% by mass, 28% to 42% by mass, or rather 15% to 30% by mass.

[0033] SBC may have an average melt flow velocity (MFR) of 3-100, 3-40, 5-35, or rather 5-20 g / 10 min, based on ASTM D 1238 (200°C / 5kg).

[0034] According to supplier reports, SBC may have an average ziblock content of 0% to 40% by mass, 0% to 30% by mass, 0% to 25% by mass, 5% to 30% by mass, 8% to 30% by mass, 10% to 25% by mass, or rather 10% to 23% by mass.

[0035] The hot melt adhesive composition may contain a total styrene block copolymer (unmodified and modified) content ranging from 6% by mass, 8% by mass, 10% by mass, 12% by mass, to 20% by mass, 22% by mass, 25% by mass, 30% by mass, 40% by mass, or any two of these values.

[0036] Unmodified styrene block copolymer The hot-melt adhesive composition contains unmodified styrene block copolymer (SBC). "Unmodified" means that the SBC is not modified / grafted with functional groups that can participate in hydrogen bonding. The hot-melt adhesive composition may contain multiple unmodified SBCs.

[0037] Unmodified SBCs have at least one A block containing styrene and at least one B block containing, for example, elastomeric conjugated dienes (e.g., hydrogenated and non-hydrogenated conjugated dienes), sesquiterpenes (e.g., hydrogenated and non-hydrogenated sesquiterpenes), and combinations thereof. The A and B blocks are bonded to each other in any manner, and the resulting copolymers exhibit a variety of structures, including, for example, random, linear, branched, radial, star-shaped, comb-shaped, tapered, and combinations thereof. Block copolymers can take any form, including, for example, linear AB blocks, linear ABA blocks, linear A-(BA)nB multiblocks, and radial (AB)nY blocks (wherein Y is a polyvalent compound and n is at least an integer of 3), tetrablock copolymers, such as ABAB, and pentablock copolymers having an ABABA structure. The adhesive composition may contain a blend of at least two different block copolymers.

[0038] Suitable styrene A blocks include, for example, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, 2,4,6-trimethylstyrene, and combinations thereof.

[0039] Suitable block elastomeric conjugated diene B blocks include, for example, butadiene (e.g., polybutadiene), isoprene (e.g., polyisoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and combinations thereof, as well as their hydrides, such as ethylene, propylene, butylene, and combinations thereof. Suitable B block sesquiterpenes include, for example, β-farnesene. The unmodified styrene block copolymer may have an unsaturated intermediate block, or the intermediate block may be saturated, i.e., hydrogenated.

[0040] In addition to the elastomeric conjugated diene B block, styrene monomer can be dispersed in the intermediate block.

[0041] Examples of useful non-modified SBCs include poly(styrene-b-butadiene) (SB), poly(styrene-b-butadiene-b-styrene) (SBS), poly(styrene-b-isoprene) (SI), poly(styrene-b-isoprene-b-styrene) (SIS), poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS), poly(styrene-b-(ethylene-alt-propylene)-b-styrene) (SEPS), poly(styrene-b-isobutylene-b-styrene) (SIBS), poly(styrene-b-(ethylene-co-butylene-co-styrene)-b-styrene) (SEBSS), and combinations thereof.

[0042] Preferred unmodified SBCs include poly(styrene-b-isoprene-b-styrene) (SIS), poly(styrene-(ethylene-co-butylene)-b-styrene) (SEBS), poly(styrene-b-(ethylene-alt-propylene)-b-styrene) (SEPS), poly(styrene-b-isobutylene-b-styrene) (SIBS), and combinations thereof.

[0043] Unmodified SBC may contain styrene content ranging from 6% by mass, 8% by mass, 10% by mass, 12% by mass, 15% by mass, 17% by mass, 20% by mass, to 25% by mass, 30% by mass, 35% by mass, 40% by mass, 45% by mass, or any two of these values.

[0044] Useful non-modified block copolymers include the KRATON D series from Kraton Corporation (Houston, Texas), such as KRATON D 1118 and the KRATON G series; the VECTOR series from Taiwan Synthetic Rubber Corporation (TSRC) (Taipei, Taiwan), such as VECTOR; and the GLOBALPRENE series from LCY Grit Corp (Taiwan), such as GLOBALPRENE 3546.

[0045] The hot melt adhesive composition contains 5% to 40% by mass, 10% to 40% by mass, 10% to 35% by mass, 10% to 30% by mass, 12% to 28% by mass, 5% to 25% by mass, 8% to 25% by mass, 10% to 25% by mass, 8% to 20% by mass, or rather 5% to 15% by mass of unmodified styrene block copolymer.

[0046] Modified styrene block copolymer The hot-melt adhesive composition contains modified SBCs. The modified SBCs in the hot-melt adhesive composition are SBCs that have been modified (more preferably grafted) with functional groups that can participate in hydrogen bonding (e.g., organic acids (e.g., carboxylic acids), anhydrides, amides, amines, ureas, carbamates, hydroxyls, carbonates, ketones, alkoxysilanes, etc.). The final SBCs may or may not contain saturated groups in the polymer backbone. Such modified styrene block copolymers can be prepared by conventional methods known in the art.

[0047] Useful modified SBC polymers include, for example, poly(styrene-b-butadiene) (SB), poly(styrene-b-butadiene-b-styrene) (SBS), poly(styrene-b-isoprene) (SI), poly(styrene-b-isoprene-b-styrene) (SIS), poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS), poly(styrene-b-(ethylene-alt-propylene)-b-styrene) (SEPS), poly(styrene-b-isobutylene-b-styrene) (SIBS), poly(styrene-b-(ethylene-co-butylene-co-styrene)-b-styrene) (SEBSS), and modified versions of those described above in the section on unmodified styrene block copolymers. Preferred modified styrene block copolymers include modified poly(styrene-b-isoprene-b-styrene) (SIS), poly(styrene-(ethylene-co-butylene)-b-styrene) (SEBS), poly(styrene-b-(ethylene-alt-propylene)-b-styrene) (SEPS), poly(styrene-b-isobutylene-b-styrene) (SIBS), and combinations thereof.

[0048] Modified SBC polymers may have structures selected from the group consisting of linear, branched, radial, and combinations thereof. When a modified SBC polymer has a radial structure, it may have 3 to 10 arms, 3 to 8 arms, or rather 3 to 6 arms.

[0049] A preferred modified SBC is a maleic anhydride-grafted SBC having a bound maleic anhydride content of 0.5% to 5% by mass, 0.7% to 3% by mass, or rather 1.0% to 2.5% by mass.

[0050] Modified SBC polymers may have a styrene content ranging from 6% by mass, 8% by mass, 10% by mass, 12% by mass, 15% by mass, 17% by mass, 20% by mass, to 25% by mass, 30% by mass, 35% by mass, 40% by mass, 45% by mass, or any two of these values. Modified SBC polymers may have a styrene content of 6% by mass to 15% by mass. Alternatively, modified SBC polymers may have a styrene content of 25% by mass to 45% by mass.

[0051] In one embodiment, the modified SBC may have a radial structure including 3 to 10 arms, a hydrogenated intermediate block, and a styrene content of 6% to 15% by mass. Alternatively, the modified SBC may have a radial structure including 3 to 10 arms having a hydrogenated intermediate block, and a styrene content of 25% to 45% by mass.

[0052] In one embodiment, the modified SBC may be a maleic anhydride-grafted SBC having a bound maleic anhydride content of 0.5% to 5% by mass, a radial structure including 3 to 10 arms, a hydrogenated intermediate block, and a styrene content of 6% to 15% by mass. Alternatively, the modified SBC may be a maleic anhydride-grafted SBC having a bound maleic anhydride content of 0.5% to 5% by mass, a radial structure including 3 to 10 arms, a hydrogenated intermediate block, and styrene content of 2 and 5% to 45% by mass.

[0053] Useful commercially available modified styrene block copolymers include the trade name KRATON, available from Kraton Corporation (Houston, Texas), for example, KRATON FG1901 and FG1924, both maleic anhydride-modified SEBS polymers; the trade name TAIPOL, available from TSRC Corporation (Kaohsiung, Taiwan), for example, TAIPOL SEBS 7126 and TAIPOL SEBS 7131, both maleic anhydride-modified SEBS polymers; and the trade name TUFTEC, available from Asahi Kasei Chemicals (Japan), for example, TUFTEC M1943, TUFTEC M1911, TUFTEC M1913, all maleic anhydride-modified, and TUFTEC MP110, which is amine-modified.

[0054] The hot melt adhesive composition contains 0.5% to 30% by mass, 2% to 30% by mass, 0.5% to 25% by mass, 0.5% to 20% by mass, 2% to 20% by mass, 0.5% to 15% by mass, 1% to 15% by mass, 1% to 13% by mass, or rather 2% to 10% by mass of modified SBC.

[0055] Tackifier The hot melt adhesive composition may contain one or more types of tackifiers.

[0056] Tackifiers may have the function of imparting tackiness to the intermediate blocks of SBCs or strengthening the terminal blocks of SBCs. Tackifiers may be fluid or solid at room temperature. Suitable classes of tackifiers include, for example, aromatic, aliphatic, and alicyclic hydrocarbon resins, mixed aromatic and aliphatic modified hydrocarbon resins, aromatic modified aliphatic hydrocarbon resins, and their hydrides; terpenes, modified terpenes, and their hydrides; natural rosins, modified rosins, rosin esters, and their hydrides; low molecular weight polylactic acid; and combinations thereof.

[0057] The tackifier may have an average R&B softening point of 90°C to 130°C, 95°C to 120°C, or rather 100°C to 115°C.

[0058] The tackifier may also be a hydrogenated hydrocarbon tackifier.

[0059] The hot-melt adhesive composition of the present invention may not contain a non-hydrogenated tackifier (e.g., a non-hydrogenated C5 resin). Non-hydrogenated tackifiers are known to increase the color and odor of the hot-melt adhesive composition and promote decomposition at high temperatures. Hydrogenated hydrocarbon tackifiers have been shown to have less odor and color, and improved thermal stability.

[0060] Suitable classes of hydrogenated hydrocarbon tackifiers include, for example, aromatic, aliphatic, and alicyclic hydrocarbon resins, aromatically modified aliphatic or alicyclic hydrocarbon resins, terpenes, modified terpenes, and combinations thereof. Examples of useful aliphatic and alicyclic petroleum hydrocarbon resins include, for example, branched and unbranched C9 and C10 resins. Examples of useful polyterpene resins include polyterpene resins, as well as copolymers and terpolymers of natural terpenes (e.g., styrene-terpene, α-methylstyrene-terpene, and vinyltoluene-terpene).

[0061] A preferred class of hydrogenated hydrocarbon tackifiers includes aromatic hydrogenated hydrocarbon resins. Aromatic hydrogenated hydrocarbon resins can be selected from the group consisting of aromatic-modified hydrocarbon resins and aromatic hydrocarbon resins.

[0062] Useful tackifying resins include those sold by ExxonMobil Chemical Company under the trade name ESCOREZ, such as ESCOREZ 5600 (molecular weight-weight average (Mw) = 800 g / mol, aromatic content 9.8%), ESCOREZ 5690 (aromatic content 10%), ESCOREZ 5615 (aromatic content 9.9%), ESCOREZ 5637 (aromatic content 5%), and ESCOREZ 5400 (aromatic content 0%, Mw = 670 g / mol), as well as those sold by Eastman Chemical (Kingsport, Tennessee) under the trade name EASTOTAC series, such as EASTOTAC H-100R and H-100L. Useful hydrogenated aromatic hydrocarbon resins include the KRISTALEX and PLASTOLYN series from Eastman Chemical Company (Kingsport, Tennessee), such as KRISTALEX 3100, PLASTOLYN 240 (Mw=4060, aromatic content 55%), and PLASTOLYN 290 (Mw=4760).

[0063] The hot melt adhesive composition contains 20% to 70% by mass, 30% to 65% by mass, about 35% to 60% by mass, or rather 40% to 60% by mass of a hydrogenated hydrocarbon tackifier.

[0064] plasticizer Plasticizers may be liquid at room temperature. Hot-melt adhesive compositions may contain multiple plasticizers.

[0065] Useful plasticizers include, for example, polybutene, polyisobutylene, polyolefin copolymers (e.g., propylene-ethylene copolymer), oligomerized α-olefins, oils (e.g., naphthenic petroleum oils, paraffinic oils, mineral oils, animal oils, vegetable oils, synthetic oils, oil derivatives, liquid isoprene, glycerol esters of fatty acids, and combinations thereof), and combinations thereof.

[0066] Useful commercially available plasticizers include, for example, the NYFLEX series of plasticizers sold by Nynas Corporation (Houston, Texas), such as NYFLEX 222B and NYFLEX 223; KAYDOL OIL from Sonneborn, LLC (Parsippany, New Jersey); KRYSTOL 550 mineral oil from Petrochem Carless Limited (Surrey, UK); and CALSOL 5550 oil from Calumet Specialty Products Partners, LP (Indianapolis, Indiana).

[0067] The composition contains 5% to 50% by mass, 10% to 50% by mass, 15% to 45% by mass, 20% to 45% by mass, or rather 30% to 42% by mass of a plasticizer.

[0068] wax Hot melt adhesive compositions may or may not contain wax, or they may contain a limited amount of wax. Useful classes of waxes include, for example, paraffin wax, microcrystalline wax, high-density low molecular weight polyethylene wax, by-product polyethylene wax, polypropylene wax, Fischer-Tropsch wax, Fischer-Tropsch oxide wax, functionalized waxes such as waxes modified with acids, anhydrides, and hydroxyls, animal waxes, plant waxes (e.g., soy wax), and combinations thereof. Useful waxes are solid at room temperature and preferably have an R&B softening point of 50°C to 170°C. The wax may also be a propylene-based wax with a Mettler softening point (ASTM D 6092) greater than 130°C, greater than 140°C, or rather greater than 150°C.

[0069] Useful waxes are commercially available from various suppliers, including the EPOLENE N and C series from Westlake Chemical Corporation (Houston, Texas), such as EPOLENE N-21, EPOLENE N-15, and EPOLENE C-13; the LICOCENE series from Clariant International Ltd. (Muttenz, Switzerland), such as LICOCENE PP 6102, LICOCENE PP 6502 TP, LICOCENE PP 7502 TP, and LICOCENE PE MA 4315; and the VISCOWAX series from Innospec Leuna GmGH (Leuna, Germany), such as VISCOWAX 116.

[0070] The hot melt adhesive composition contains wax in amounts of less than 5% by mass, less than 4.5% by mass, less than 4% by mass, less than 3.5% by mass, less than 3% by mass, less than 2% by mass, 0% to 4.5% by mass, 0% to 4% by mass, 0% to 3.5% by mass, and 0% to 3% by mass.

[0071] Optional components The composition may optionally contain a variety of additional components, including, for example, fillers, superabsorbents, surfactants, flame retardants, additional polymers (e.g., olefin polymers), and various additives (e.g., co-extruded coatings, packaging films, stabilizers, antioxidants, adhesion promoters, UV stabilizers, rheology modifiers, biocides, corrosion inhibitors, dehydrators, colorants (e.g., pigments and dyes), optical whitening agents, and combinations thereof).

[0072] Useful antioxidants include, for example, pentaerythritol tetrakis[3,(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis(4-methyl-6-tert-butylphenol), phosphyto, such as tris-(p-nonylphenyl)-phosphyto (TNPP), and bis(2,4-di-tert-butylphenyl)4,4'-diphenylene-diphosphonit, di-stearyl-3,3'-thiodipropionate (DSTDP), as well as combinations thereof. Useful antioxidants include, for example, the IRGANOX series, all available from BASF Corporation (Florham Park, New Jersey), such as IRGANOX 1010, IRGANOX 565, and IRGANOX 1076 hindered phenol antioxidants, and IRGAFOS 168 phosphyto antioxidant, as well as ETHYL 702, which is 4,4'-methylenebis(2,6-di-tert-butylphenol), and the BNX series from Mayzo, Inc. (Swanee, Georgia), such as BNX 1010 and BNX 1076, which are commercially available under various trade names. When antioxidants are present, the adhesive composition preferably contains about 0.1% to about 2% by mass of antioxidants.

[0073] Purpose Hot melt adhesive compositions are useful for a variety of applications and structures, including, for example, disposable absorbent articles such as disposable diapers, adult incontinence products, sanitary napkins, medical bandages (e.g., wound care products), adhesive bandages, surgical pads, pet training pads (e.g., puppy pads), and meat packaging products, as well as components of absorbent articles, such as absorbent elements, absorbent cores, impermeable layers (e.g., backsheets), tissues (e.g., packaging tissues), trapping layers, and woven and nonwoven web layers (e.g., topsheets, absorbent tissues).

[0074] Hot melt adhesive compositions can also be applied to a variety of substrates, including, for example, films (e.g., polyolefins (e.g., polyethylene and polypropylene), polyesters, metallized polymers, multilayer, biaxially oriented, and uniaxially oriented ethylene-vinyl acetate copolymers, polyurethanes, vinyls, polyvinylidene fluoride, cellulose acetate and ethylcellulose, and polyamide films, and combinations thereof), metal foils, release liners, porous substrates, cellulose substrates, sheets (e.g., paper and fiber sheets), paper products, woven and nonwoven webs, fibers (e.g., natural cellulose fibers such as wood pulp, cotton, silk, and wool; cellulose fibers; synthetic polymer fibers such as nylon, rayon, polyester, acrylic, polypropylene, polyethylene, polyvinyl chloride, and polyurethane; glass fibers; regenerated fibers; and various combinations thereof), and tape backings. Useful substrates include, for example, single-layer, multilayer, treated (e.g., corona-treated or chemically undercoated) substrates and untreated substrates, and combinations thereof.

[0075] Uses within disposable absorbent articles Positioning The hot-melt pressure-sensitive adhesive composition of the present invention is useful as a positioning adhesive to be placed on at least one substrate surface of a disposable absorbent article, and can be used to position absorbent articles on clothing such as underwear. Examples of such disposable absorbent articles include women's hygiene products such as sanitary napkins and panty liners, diapers, disposable clothing with waist and leg openings, and adult incontinence products.

[0076] In one structure, a disposable absorbent article (e.g., a feminine hygiene article) includes a surface facing clothing and a surface facing the body, a top sheet having the surface facing clothing and the surface facing the body, a back sheet having the surface facing clothing and the surface facing the body, and optionally an absorbent core positioned between the body-facing surface of the back sheet and the clothing-facing surface of the top sheet. The absorbent core may be optional for absorbent articles with limited absorption capacity, but certain top sheets, such as a high-loft top sheet, may also function as the absorbent portion of the article.

[0077] The top sheet defines the body-facing surface of the absorbent article. The absorbent core is positioned from the outer periphery inward of the absorbent article. The absorbent structure includes a back sheet positioned adjacent to the body-facing surface and the clothing-facing surface. A positioning adhesive composition is placed between the release liner and the back sheet, and the back sheet is permanently bonded to the absorbent core via a permanent adhesive composition. The top sheet is permanently bonded to the absorbent core via a discontinuous permanent adhesive composition. The top sheet and back sheet are joined together, and the sealed edges of the top sheet and back sheet define the entire sealed periphery of the article. The absorbent article can be any suitable shape and size.

[0078] The top sheet is designed to come into contact with the user's body and is liquid-permeable. The exposed surface of the liquid-permeable top sheet is designed to receive aqueous fluids from the body, which then move away from the user's body towards the absorbent core. The top sheet is made of any suitable material through which body exudates can easily permeate. The top sheet optionally includes multiple openings formed therein to allow body fluids to move more easily into the absorbent core.

[0079] The backsheet is liquid-impermeable and designed to face the inner surface of the user's clothing (e.g., underwear), i.e., the crotch area. The backsheet is optionally configured to block the passage of liquids while allowing air or vapor to pass through the absorbent material (e.g., a vapor permeable layer).

[0080] The hot-melt pressure-sensitive adhesive composition is generally placed on the garment-facing side of the absorbent article, or rather, on the garment-facing side of the backsheet. A release liner is optionally placed on the pressure-sensitive hot-melt adhesive composition to protect it until use. The absorbent article (e.g., feminine hygiene article) optionally includes additional layers and adhesives, and the components of the absorbent article optionally exhibit additional functions. Examples of additional layers, functions, and combinations thereof include dusting, wicking, acquisition, additional top sheets, multiple core layers, superabsorbent particles and compositions, wetness indicators, and combinations thereof.

[0081] The two types of fabrics currently in common use that require positioning adhesives for bonding are cotton and microfiber. Cotton fabric refers to textiles made from 100% cotton fibers. Microfiber is a fabric made by densely weaving synthetic fibers with a diameter of less than 10 micrometers. Several chemicals (often polar materials, such as polyester and polyamide) can be used in the production of microfiber fabrics.

[0082] Core stabilization The hot-melt adhesive composition of the present invention can be used to house, fix, and / or strengthen (i.e., stabilize the core) an absorbent core of a disposable absorbent article.

[0083] The absorbent core includes the core and, optionally, a core wrap. The absorbent core can be manufactured in-line (i.e., in a disposable absorbent article) on an assembly line. Alternatively, the core can be manufactured offline and then wound or fested for later or in a different location. The core may vary in design, shape, and materials used. The core may have a rectangular shape or a dogbone shape. The core may be a single continuous shape or may be divided into channels formed, for example, by a top sheet and a back sheet.

[0084] The core is typically placed in the center of the article and is securely fixed between the top sheet and the back sheet by mounting means (e.g., adhesive).

[0085] The core includes an absorbent material capable of absorbing bodily fluids and solids received through the top sheet. The core may include cellulose fibers (i.e., fluff), wood pulp, cotton, synthetic fibers, nonwoven fabrics, tissue, foam, superabsorbent polymers (e.g., polyacrylate), or any other absorbent material.

[0086] The absorbent core may contain less than 10% by mass of fluff, or rather may contain no fluff at all. In cores with little or no fluff, the absorbent core is composed of a hot melt adhesive composition, a superabsorbent polymer, and optionally a layer of nonwoven fabric and / or tissue.

[0087] The core may be a composite core. The composite core may contain less than 10% by mass of fluff, or rather may not contain any fluff at all. The composite core includes a plurality of SAP layers in which layers of nonwoven fabric or tissue and a hot melt adhesive composition are alternately layered. The composite core may include 1 to 5 layers, or rather 2 to 4 layers, of individual SAP layers in which the hot melt adhesive composition and nonwoven fabric or tissue are alternately layered.

[0088] The core wrap can be any material that encloses the core and holds its components in place. Generally, the core wrap is wrapped around two of the core's longer sides, leaving the ends open. The core wrap can be selected from the group consisting of nonwoven fabrics and tissues.

[0089] Hot melt adhesive compositions can be used to hold absorbent materials in the appropriate position in both dry (non-expanding) and wet (swollen) states.

[0090] The absorbent core can be used in a variety of disposable absorbent articles, including, for example, disposable diapers, adult incontinence products, sanitary napkins, medical bandages (e.g., wound care products), adhesive bandages, surgical pads, pet training pads (e.g., puppy pads), and meat packaging products.

[0091] Assembly Hot melt adhesive compositions can also be used for assembly applications. In a typical assembly application in the manufacture of disposable absorbent articles, a fluid-impermeable backsheet is bonded to a nonwoven fabric substrate. In other assembly applications, nonwoven fabric substrates are bonded to other nonwoven fabric substrates. Hot melt adhesive compositions can also be used to bond at least one additional layer or material selected from the group consisting of absorbents, tissues, elastomer materials, superabsorbent polymers, and combinations thereof. For example, hot melt adhesive compositions can further be used for lamination of backsheets, i.e., to bond a fluid-impermeable backsheet, typically a polyolefin film (e.g., polyethylene, polypropylene, ethylene vinyl acetate, ethylene copolymer, etc.) to a second nonwoven fabric to improve the feel of the disposable article.

[0092] Elastic attachment Hot-melt adhesive compositions can be used in elastic attachment applications, including bonding elastic materials (e.g., strands, films, etc.) to components of disposable absorbent articles. Elastic materials can be coated with a hot-melt adhesive composition in a stretched form and then bonded to a film (e.g., polyethylene, polypropylene, etc.) or nonwoven fabric substrate. The elastic material coated with the hot-melt adhesive composition can also be bonded between these two substrates. This process yields gathers that exhibit creep resistance after tension release.

[0093] Alternatively, the adhesive can be applied to a film or nonwoven fabric substrate, and then an elastic material can be bonded to it. Hot melt adhesive can be used as an elastic attachment adhesive when forming ears / tabs of disposable absorbent articles. Alternatively, hot melt adhesive can be further used as an elastic attachment adhesive to enhance the elasticity of the leg openings or waist portions of disposable absorbent articles.

[0094] Further applications In addition to various applications in disposable absorbent articles, the hot-melt adhesive composition of the present invention can also be used as an adhesive for various tapes to be applied to the skin (e.g., medical tapes and bandages, wearable devices (e.g., colostomy bags), athletic tapes and kinesiology tapes, wound dressings, etc.), as well as for adhering labels to various items, including containers, and for any application requiring adhesion to dissimilar substrates.

[0095] Hot melt adhesive compositions are useful in a variety of forms, including, for example, coatings (e.g., continuous and discontinuous coatings (e.g., random, patterned, arranged, spiral, dot, spot, and combinations thereof)), films (e.g., continuous and discontinuous films), beads, sheets, fibers, filaments, webs (e.g., woven and nonwoven fabrics), and combinations thereof.

[0096] Various coating techniques can be used to apply the adhesive composition to a substrate, including, for example, slot coating, spraying (e.g., spiral spraying and random spraying), screen printing, foaming, engraving rollers, extrusion, meltblown adhesive coating techniques, and combinations thereof.

[0097] The present invention will be explained by the following examples. [Examples]

[0098] Test Procedure The test procedure includes the following: Unless otherwise specified, all ratios and percentages are on a mass basis. Unless otherwise specified, the procedure is carried out at room temperature (i.e., ambient temperature of approximately 20°C to approximately 25°C). Unless otherwise specified, the properties described for the components used in the composition are those reported by the manufacturer.

[0099] Brookfield viscosity test method Brookfield viscosity is determined using a Brookfield Thermocell viscometer model RVDV2 and spindle #27, according to ASTM D-3236, titled "Standard Test Method for Apparent viscosity of Hot Melt Adhesives and Coating Materials" (October 31, 1988). Results are reported in centipoise (cP), and the test is performed at the specified temperature.

[0100] Method for preparing test samples for peeling force on cotton and microfibers The laminate is prepared by applying the sample composition to silicone-coated release paper in a 1-inch wide pattern at a rate of 20 grams / m² (g / m²) using a slot applicator. 2 )(±3g / m 2The silicone-coated release paper / adhesive / polyethylene film laminate is prepared by coating with an additional mass of ) and then bringing the adhesive strip into contact with the treated surface of a 1 mil (0.025 mm) thick polyethylene film. A test specimen is then cut from the laminate, having a length of 4 inches (in) (10.16 cm) in the longitudinal direction and 1.5 inches (3.81 cm) in the width direction, such that the adhesive pattern is centered in the width direction of the test specimen.

[0101] For cotton bonding, 124g / m 2 Cut a sheet of bleached T-shirt cotton cloth (Testfabrics, Inc., West Pitston, Pennsylvania) into strips 4 inches (10.16 cm) long longitudinally and 1.5 inches (3.81 cm) wide transversely, but inspect the seam grid pattern of the cloth before cutting. When the cotton cloth is stretched, the sample will show that it stretches more in one direction than in another. Cut the cotton cloth longitudinally along the direction of less stretch. Cut all cotton cloth strips as straight as possible along the seam grid pattern. Cutting the cotton cloth strips diagonally will result in uneven stretch in the cotton cloth test sample.

[0102] The release film is peeled off the adhesive, and the adhesive side of each test sample is gently placed on the surface of the cotton strip so that the cotton is rolled up towards the adhesive joint (in the longitudinal direction) to form a composite test sample. When preparing the composite test sample, the adhesive is not pressed onto the cotton cloth.

[0103] For microfiber bonding, the target mass is 135 g / m 2 The LUCERO polymer microfiber sheet (Termileniao SA), made from 70% polyamide and 30% elastomer, will be used. Before the test, the fabric will first be washed without detergent, and then cut into 2-inch (5.08 cm) x 8-inch (20.32 cm) strips along the long edge of the fabric to prevent stretching.

[0104] Carefully cut each 8-inch (20.32 cm) strip in half to create two 4-inch (10.16 cm) strips. Then, turn one of these strips inside out to expose the opposite side of the fabric. Place the adhesive sample on each 4-inch (10.16 cm) strip to create an equal number of bonded samples on each side of the fabric.

[0105] Method for testing the peel strength of cotton and microfibers At least five samples are prepared according to the Peel Force Sample Preparation Method. The test samples are placed in a 2 kg mechanical roll-down device, and the rollers are passed over the film side of the sample twice, once forward and once backward, at a speed of 305 mm / min. Then, the timer is activated and the samples are placed in the jaws of an INSTRON type peel tester. The polyethylene film is placed in the movable jaw and the fabric is attached to the fixed jaw. Within one minute of removing the samples from the roll-down device, the samples are tested according to ASTM D1876-01, titled "Test Method for Determining Peel Resistance of Adhesive (T-Peel Test Method)," except that the test is performed over 10 seconds at a speed of 305 mm / min instead of 250 mm / min, and at least five repetitions are performed instead of the 10 repetitions specified in ASTM D1876. Record the average peeling force during a 10-second peeling period and report the results in Newtons / cm.

[0106] The peeling force is measured 24 hours after the test sample is prepared.

[0107] Wet and warm peeling test method Fabric laminates were prepared according to the test method described above. The laminates were incubated in a Thermotron oven at 40°C and 90% relative humidity for 2 hours. Within 10 minutes of removal from the Thermotron, a peel test (305 mm / min) was performed on each laminate.

[0108] Sample preparation for 180-degree peel adhesion tests on HDPE or stainless steel. This test method is used to test and measure the 180-degree peel adhesion value of PSA (including semi-PSA and ultra-removable PSA) to high-density polyethylene (HDPE) or stainless steel panels. Sample laminates are prepared using a benchtop roll-to-roll laminating machine. Using a slot applicator, adhesive is applied to an untreated PET (Mylar) film with a 2-mil (0.051 mm) shim at 149°C and bonded to a peel-treated PET (Mylar) film to form a laminate. The laminate is cut longitudinally into 1-inch x 8-inch (25 mm x 200 mm) strips. The HDPE or stainless steel test panel is cleaned with toluene and isopropyl alcohol. The peel-off PET liner is removed. Three samples are placed longitudinally on the HDPE or stainless steel panel so that a 5-inch (125 mm) adhesive strip is in contact with the panel. A 2 kg roller is rolled three times in the back-and-forth direction to ensure no bubbles or wrinkles are present on the samples. The samples are allowed to stand for 1 minute before the peel test to allow them to set.

[0109] 180-degree peel adhesion test method for HDPE or stainless steel The 180-degree peel adhesion strength is measured using an INSTRON peel tester. The HDPE or stainless steel plate is secured with the lower jaws so that the "unsecured tab" of the sample faces downwards. The unsecured tab of the sample is secured using the upper jaws of the INSTRON (attached to the load cell). The peel force (N) is measured by moving the crosshead at a speed of 305 mm / min, according to PSTC 101, titled "Peel Adhesion of Pressure Sensitive Tape". The values ​​shown are the average of at least three repeated tests.

[0110] Sample preparation for loop tack strength testing of HDPE or stainless steel. The laminate is coated and fabricated according to the same method as described in the above "Sample Preparation for 180 - degree Peel Adhesion Test for HDPE or Stainless Steel". The laminate is cut into test strips 5 inches (125 mm) long in the longitudinal direction. The test panel (HDPE or stainless steel) is cleaned with toluene and isopropyl alcohol.

[0111] Loop Tack Strength Test Method for HDPE or Stainless Steel The loop tack strength is measured using an INSTRON - type peel tester with a clamp jaw attached to the load cell of the upper crosshead and a loop tack fixture attached to the base. The HDPE or stainless steel plate is clamped to the loop tack fixture so that it is placed flat. Remove the backing of the test laminate, staple one sheet of paper between the loop ends with the adhesive side facing outwards to form a loop. Attach the stapled loop ends to the upper jaw of the INSTRON. Lower the sample onto the HDPE or stainless steel plate until the entire 1 - inch × 1 - inch (25 mm × 25 mm) area of the test plate is completely covered with the exposed adhesive. To measure the loop tack value, move the crosshead upwards at a speed of 305 mm / min and record the peak force in units of N. The values shown are the average of at least 3 repeated tests.

[0112] Test Sample Preparation Method for "Core" Peel Force for Non - woven Fabric, Cotton, and Cellulose Towel Substrates The laminate is made by coating the sample composition, using a slot applicator, onto a roll - shaped hydrophilic non - woven fabric (Avgol Americas, Mocksville, North Carolina) at a rate of 8 grams per square meter (g / m 2 ) in a pattern 3 inches (7.62 cm) wide with an additional mass of 5 g / m 2 (±0.5 g / m 2 ). Then, the adhesive strip is brought into contact with one of the three substrates: 1) the same hydrophilic non - woven fabric joined as the second roll - shaped substrate; 2) 124 g / m 21) A sheet of bleached T-shirt cotton cloth (Testfabrics, Inc., West Pittston, Pennsylvania) measuring 20 inches (in) (50.8 cm) in the longitudinal direction and 8 inches (20.3 cm) in the width direction. This cotton sheet is in contact with the adhesive strip and sandwiched between another nonwoven fabric layer;3) A sturdy cellulose towel (Wypall, Kimberly-Clark, Irving, Texas) is cut into 6-inch (15.2 cm) long and 6-inch (15.2 cm) wide squares. This cellulose towel is in contact with the adhesive strip and sandwiched between another nonwoven fabric layer. The web speed of the hydrophilic nonwoven fabric is 525 ft / min (160 m / min). The laminate is tensioned with two "s-wrap" pack rollers, not nip compression. The web tension held on each substrate was 0.25 pounds / linear inch (PLI, 44 N / m).

[0113] Laminates for peel testing were prepared in two ways: 1) Nonwoven-nonwoven laminates were cut widthwise so that the longitudinal adhesive strips (3 inches wide) were approximately 5 inches long. Paper flags were inserted perpendicularly into the web during the coating process to ensure a smooth start to the peel test. Nonwoven-cotton and nonwoven-cellulose towel laminates were cut widthwise using a precision cutter to 1.5 inches wide and 3 inches long for the adhesive.

[0114] Method for preparing test samples of backsheet laminates for nonwoven fabrics and poly films The laminate is prepared by applying the sample composition to a hydrophobic nonwoven fabric (5 inches wide, 14 gsm basis weight, Unipro) in a 3-inch (7.6 cm) pattern at a rate of 3 grams / m². 2 (±0.25g / m²) 2The webs were fabricated by coating with an additional mass of ) and then contacting an adhesive strip with a corona-treated, non-breathable polyethylene film (6 inches wide / 15.24 cm, 18 gsm, Berry Global, Evansville, Indiana). The web speed was 525 ft / min (160 m / min). The laminates were tensioned with two "S-wrap" pack rollers, rather than by nip compression. The web tension held on each substrate was 0.25 pounds / linear inch (PLI, 44 N / m).

[0115] The laminate for the peel test was fabricated so that the longitudinal adhesive strips (3 inches wide) were approximately 6 inches long. Paper flags were inserted into the web during the coating process to ensure a smooth start to the peel test.

[0116] Dry peel strength test method for hydrophilic nonwoven fabric, cotton, and cellulose towel "core" At least eight nonwoven-nonwoven laminate samples are prepared according to the specified method (four samples on the upper web side and four samples on the lower web side, longitudinally from the flag). The samples are placed in the jaws of an INSTRON type peel tester. The "bonding side" (hydrophilic nonwoven fabric, cotton, or cellulose towel) of each laminate is placed in the movable jaw, and the "coating side" (hydrophilic nonwoven fabric) of each laminate is placed in the fixed jaw. The samples are tested according to ASTM D1876-01, titled "Test method for measuring the peel resistance of adhesives (Type T peel test method)," except that the test is performed over 10 seconds at a speed of 305 mm / min instead of 250 mm / min, and at least eight repeated tests are performed instead of the 10 tests specified in ASTM D1876. The average peel force during the 10-second peel is recorded, and the results are reported in Newtons / cm (N / cm). The peel strength of the nonwoven fabric-cotton nonwoven fabric-cellulose towel laminate was measured using the above test method, however, instead of the 10 repetitions specified in ASTM D1876, 5 repetitions were performed for each type.

[0117] The dry peel strength is measured 24 hours after the test laminate is prepared.

[0118] Method for testing the wet peel strength of hydrophilic nonwoven fabrics, cotton, and cellulose towels "cores" At least eight nonwoven fabric-to-nonwoven fabric samples are prepared according to the specified method (four samples on the upper web side and four samples on the lower web side, longitudinally from the flag). Each laminate is completely immersed in a 0.9% mass / mass saline solution for 3 minutes. Then, each laminate is placed on a drying rack (not stacked) and drip-dried for 5 minutes, after which the peel force is measured. The timer is then activated and the samples are placed in the jaws of an INSTRON type peel test machine. Within 5 minutes after the completion of the drip-drying process, each laminate is subjected to a peel test. The "bonding side" (hydrophilic nonwoven fabric, cotton, or cellulose towel) of each laminate is placed in the movable jaw, and the "coating side" (hydrophilic nonwoven fabric) of each laminate is placed in the fixed jaw. The samples were tested according to ASTM D1876-01, titled "Test method for measuring the peel resistance of adhesives (Type T peel test method)," except that the test was performed over 10 seconds at a speed of 305 mm / min instead of 250 mm / min, and at least 8 repetitions were performed instead of 10 as specified in ASTM D1876. The average peel force during the 10-second peel was recorded, and the results were reported in Newtons / cm. The peel force of nonwoven-cotton nonwoven-cellulose towel laminates was measured using the above test method, except that 5 repetitions were performed for each type instead of 10 as specified in ASTM D1876.

[0119] The wet peel strength is measured 24 hours after the test laminate is prepared.

[0120] Method for testing the peel strength of nonwoven fabric-polyethylene film "backsheet laminates" At least eight nonwoven-polyfilm samples are prepared according to the specified method (four samples on the upper web side and four samples on the lower web side, longitudinally from the flag). The samples are placed in the jaws of an INSTRON type peel tester. The "bonding side" (polyethylene film) of each laminate is placed in the movable jaw, and the "coating side" (hydrophobic nonwoven fabric) of each laminate is placed in the fixed jaw. The samples are tested according to ASTM D1876-01, titled "Test method for measuring the peel resistance of adhesives (Type T peel test method)," except that the test is performed over 10 seconds at a speed of 305 mm / min instead of 250 mm / min, and at least eight repeated tests are performed instead of the 10 tests specified in ASTM D1876. The average peel force over 10 seconds is recorded, and the results are reported in Newtons / cm.

[0121] The initial dry peel strength is measured 24 hours after the test laminate is prepared. The same set of laminates is accelerated to 49°C for 28 days, and the peel strength is measured after the aging process. Then, the aged laminates are adjusted in a room according to ASTM D1876 for at least 1 hour before conducting the peel test.

[0122] The adhesive compositions were prepared by mixing the components in the amounts shown in Tables 1 and 2 in a sigma blade mixer operating at 177°C under nitrogen. The adhesive compositions were then tested according to various test methods. These results are reported in Tables 1 and 2 below.

[0123] [Table 1]

[0124] [Table 2]

[0125] Other embodiments are described in the claims.

Claims

1. i) 5% to 40% by mass of unmodified styrene block copolymer, ii) 0.5% to 15% by mass of modified styrene block copolymer, iii) A tackifier in an amount of 30% to 65% by mass, and iv) 10% to 45% by mass of plasticizer A hot melt adhesive composition containing, A hot-melt adhesive composition containing less than 5% by mass of wax.

2. The hot melt adhesive composition according to claim 1, wherein the modified styrene block copolymer is a styrene block copolymer modified with an organic acid or an anhydride, selected from the group consisting of poly(styrene-b-(ethylene-co-butylene)-b-styrene, poly(styrene-b-(ethylene-alt-propylene)-b-styrene), and poly(styrene-b-isobutylene-b-styrene).

3. A hot melt pressure-sensitive adhesive composition comprising the hot melt adhesive composition according to claim 1 or 2.

4. i) 1% to 10% by mass of modified styrene block copolymer, ii) 15% to 45% by mass of plasticizer Includes, The tackifier is a hydrogenated hydrocarbon, the plasticizer is an oil, and the hot melt adhesive composition is a pressure-sensitive adhesive. A hot melt adhesive composition according to any one of claims 1 to 3.

5. The hot melt adhesive composition according to any one of claims 1 to 4, wherein the total of the unmodified styrene block copolymer and the modified styrene block copolymer has an average styrene content of 25% to 45% by mass and an average diblock content of 10% to 25% by mass.

6. The hot melt adhesive composition according to any one of claims 1 to 5, wherein the total of the unmodified styrene block copolymer and the modified styrene block copolymer has an average styrene content of 15% to 30% by mass and an average diblock content of 10% to 25% by mass.

7. A disposable absorbent article comprising the hot melt adhesive composition according to any one of claims 1 to 6.

8. An article selected from the group consisting of medical tapes, bandages, wearable devices, athletic tapes, kinesiology tapes, and wound dressings, comprising the hot melt adhesive composition according to any one of claims 1 to 7.

9. A hot melt adhesive composition according to any one of claims 1 to 8, wherein the initial peeling of cotton does not decrease when tested according to a wet warm peel test method.

10. A hot melt adhesive composition according to any one of claims 1 to 9, comprising less than 4% by mass of wax.

11. A hot melt adhesive composition according to any one of claims 1 to 10, having a Brookfield viscosity of 15,000 cP or less at 121°C.

12. The hot melt adhesive composition according to any one of claims 1 to 11, wherein the modified styrene block copolymer has a radial structure including 3 to 10 arms, a hydrogenated intermediate block, and a styrene content of 6% to 15% by mass.

13. The hot melt adhesive composition according to any one of claims 1 to 12, wherein the modified styrene block copolymer has a radial structure including 3 to 10 arms, a hydrogenated intermediate block, and a styrene content of 25% to 45% by mass.

14. A hot melt adhesive composition according to any one of claims 1 to 13, having a total styrene block copolymer content of 8% to 25% by mass.

15. A hot melt adhesive composition according to any one of claims 1 to 14, wherein a modified styrene block copolymer, a styrene block copolymer, a tackifier, and a plasticizer constitute at least 90% by mass of the hot melt adhesive composition.

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