Method for recycling post-consumer absorbent articles

Abstract

The present invention relates to a method for recovering plastic material from a post-consumer disposable absorbent article comprising a topsheet, a backsheet, an absorbent core, a hot melt adhesive composition H. At least one of the topsheet and the backsheet comprises at least one plastic material, wherein the hot melt adhesive composition H comprises: # imgabs0 # at least one polymer P selected from the group consisting of thermoplastic block copolymers of polyolefins, vinyl-based aromatic hydrocarbons and conjugated diene compounds and mixtures thereof; # imgabs 1 # at least one tackifier T comprising at least one ester or carboxylic acid group; the present invention relates to a method for producing a disposable absorbent article, said method being characterized in that it comprises:-step i): providing a post-consumer disposable absorbent article,-step ii): immersing the post-consumer disposable absorbent article in an aqueous alkaline solution under conditions sufficient to obtain debonding of the plastic material,-step iii): separating and recovering the plastic material from the medium.

Description

Technical Field

[0001] The present invention relates to a method for recycling post-consumer absorbent articles.

[0002] The present invention also relates to a method for recycling plastic material from post-consumer absorbent articles. Background Art

[0003] Hundreds of billions of soiled disposable absorbent articles (e.g., diapers) are disposed of as solid waste each year. Only a small fraction is recycled, primarily due to a lack of technology suitable for such articles.

[0004] The complexity of disposable absorbent articles stems from consumer demand for comfortable, effective, easy-to-use, and low-cost products. However, this system has made traditional recycling impossible to carry out effectively and cost-effectively with current technology. As a result, post-consumer disposable diapers end up as solid waste in landfills or are incinerated.

[0005] The use of incineration or landfill disposal results in the loss or destruction of components of the absorbent article, rather than recycling some or all of the components to the same or other end use.Disposal issues are of increasing concern to environmental and governmental authorities.

[0006] Recently, some attempts have been made to recycle used disposable absorbent articles. However, some methods often use significant amounts of hazardous extraction solvents. Other methods first involve breaking the disposable absorbent articles into small pieces before the washing process, which does not allow for good quality recovery of the individual substrates of the disposable absorbent articles and requires additional purification steps.

[0007] There is a need for a new method of recycling used disposable absorbent articles which at least partially remedies at least one of the mentioned disadvantages.

[0008] More particularly, there is a need for an efficient and economical method for recycling used disposable absorbent articles into their individual components without harming the environment.

[0009] There is a need for an efficient, easy to implement and economical process for recycling used disposable absorbent articles. Summary of the Invention

[0010] A.Recycling Method

[0011] The present invention relates to a method for recycling plastic materials from post-consumer disposable absorbent articles, wherein the post-consumer disposable absorbent article comprises a top sheet, a back sheet, an absorbent core material, a hot melt adhesive composition H, wherein at least one of the top sheet and the back sheet comprises at least one plastic material,

[0012] The hot melt adhesive composition H comprises:

[0013] at least one polymer P selected from the group consisting of polyolefins, thermoplastic block copolymers of vinyl-based aromatic hydrocarbons and conjugated diene compounds, and mixtures thereof;

[0014] at least one tackifier T comprising at least one ester group or carboxylic acid group;

[0015] The method is characterized in that the method comprises:

[0016] - step i): providing a post-consumer disposable absorbent article,

[0017] - step ii): immersing the post-consumer disposable absorbent article in an alkaline aqueous solution under conditions sufficient to obtain debonding of the plastic material,

[0018] - Step iii): separation and recovery of the plastic material from the medium.

[0019] Post-consumer disposable absorbent products

[0020] As used herein, "absorbent article" refers to consumer products whose primary function is to absorb and retain soil and waste.

[0021] As used herein, "diaper" refers to an absorbent article generally worn by infants and incontinent persons about the lower torso.

[0022] The term "post-consumer product" relates to a product that has been used at least once by a consumer.

[0023] The term "disposable" is used herein to describe absorbent articles that are not typically intended to be laundered or restored or reused as an absorbent article (eg, they are intended to be discarded after a single use).

[0024] The term "nonwoven" herein refers to materials made from continuous (long) filaments (fibers) and / or discontinuous (short) filaments (fibers) by processes such as, for example, spunbonding, meltblowing, carding, etc. Nonwovens do not have a woven or knitted filament pattern.

[0025] The disposable absorbent article may be a disposable diaper, an adult incontinence product, a sanitary napkin, a medical dressing (such as a wound care product), a surgical pad, a pet training pad. Preferably, the disposable absorbent article is a disposable diaper.

[0026] The disposable absorbent article comprises a top sheet, a back sheet, an absorbent core material and a hot melt adhesive H. The disposable absorbent article may further comprise one or more hot melt adhesives, for example, for bonding elastic materials, core materials and the like.

[0027] Typically, disposable absorbent articles comprise a liquid permeable topsheet facing the wearer's body, a liquid impermeable backsheet facing the wearer's clothing (garment), an absorbent core interposed between the liquid permeable topsheet and the backsheet, and a film intended to hold the core in place relative to the wearer's body.

[0028] The plastic material is preferably selected from the group consisting of: polyolefins (such as eg polyethylene, polypropylene...), polyesters (such as eg polyethylene terephthalate, polybutylene terephthalate), polyamides (such as eg 6-nylon, 6,6-nylon), poly(lactic acid) and mixtures thereof.

[0029] Absorbent core

[0030] The function of the absorbent core is generally to absorb and retain exudates for an extended period of time, minimizing rewet to keep the wearer dry and avoid soiling of clothing or bed linens.

[0031] Most absorbent cores typically comprise absorbent material within a core-around-wrap.

[0032] The absorbent core may comprise different absorbent materials including natural cellulosic fibers (eg, wood pulp, fibers, cotton, or fluff), superabsorbent polymers (SAP), or mixtures thereof.

[0033] The superabsorbent polymer (SAP) can be selected from: modified natural gums, carboxymethyl cellulose, alkali metal salts of acrylic polymers, polyacrylamide, polyvinyl alcohol, polyvinyl ether (co)polymers, hydroxyalkyl cellulose (co)polymers, polyvinyl sulfonic acid (co)polymers, polyacrylic acid (co)polymers, and mixtures thereof.

[0034] Preferably, the absorbent core comprises superabsorbent polymer (SAP).

[0035] Examples of superabsorbent polymers are disclosed in WO 2009 / 155265 or WO 2009 / 155264.

[0036] Longitudinally extending fluid distribution channels can be used. Channels can quickly distribute the barrier fluid across a larger area of ​​the absorbent core, thereby improving fluid acquisition and optimizing the use of the absorbent material. Channels can also be used to facilitate folding the absorbent core in a predetermined pattern, thereby improving the anatomical conformity of the article.

[0037] The core wrap may typically comprise one or two layers of non-woven plastic material, such as PP (polypropylene) or PE (polyethylene).

[0038] Top sheet

[0039] The liquid pervious topsheet advantageously permits liquids (eg, menstrual fluid and / or urine) to readily penetrate through its thickness.

[0040] The topsheet may comprise woven and nonwoven materials, porous foams, reticulated foams, synthetic films, and mixtures thereof.

[0041] The nonwoven material may comprise natural fibers (e.g., wood fibers, cotton fibers, bamboo fibers, lyocell fibers, ...), synthetic fibers (e.g., polymeric fibers such as polyesters, polyolefins, ethylene vinyl acetate polymers, ethylene acrylic polymers, and mixtures thereof), and mixtures thereof.

[0042] According to the present invention, the (post-consumer) disposable article is such that at least one of the topsheet and the backsheet comprises at least one plastic material.

[0043] Preferably, the topsheet comprises at least one plastic material.

[0044] The topsheet may comprise one or several different plastic materials.

[0045] The different plastic materials may be selected from different types of plastic, eg a first plastic being a polyolefin and a second plastic being a polyester, or they may be from the same type: eg polyolefin, but the first plastic being polyethylene and the second plastic being polypropylene.

[0046] The plastic material in the topsheet may be the same as or different from the plastic material of the backsheet.

[0047] Plastic materials generally include nonwoven materials, plastic films, rubber and the like.

[0048] The plastic material is preferably selected from the group consisting of: polyolefins (such as eg polyethylene, polypropylene...), polyesters (such as eg polyethylene terephthalate, polybutylene terephthalate), polyamides (such as eg 6-nylon, 6,6-nylon), poly(lactic acid) and mixtures thereof.

[0049] The topsheet preferably comprises a nonwoven material, which preferably comprises a plastic material.Even more preferably, the topsheet comprises a nonwoven material comprising polypropylene, more particularly polypropylene fibers.

[0050] The topsheet may have a basis weight of 10 to 28 gsm, specifically 12 to 18 gsm, although other basis weights are possible.

[0051] negatives

[0052] The backsheet advantageously prevents exudates absorbed and contained in the absorbent core from wetting articles in contact with the absorbent article.

[0053] The backsheet is typically impervious to liquids (eg, urine).

[0054] The backsheet may comprise a woven or nonwoven material, a synthetic film, or a composite of a nonwoven material and a synthetic film.

[0055] The nonwoven material can comprise natural fibers (eg, wood fibers or cotton fibers), synthetic fibers (eg, polymeric fibers such as polyesters, polyolefins, ethylene vinyl acetate polymers, ethylene acrylic polymers, and mixtures thereof), and mixtures thereof.

[0056] Preferably, the backsheet comprises at least one plastic material.

[0057] The backsheet may consist of one or several different plastic materials

[0058] The plastic material in the backsheet may be the same as or different from the plastic material of the topsheet.

[0059] The different plastic materials may be selected from different types of plastic, eg a first plastic being a polyolefin and a second plastic being a polyester, or they may be from the same type: eg polyolefin, but the first plastic being polyethylene and the second plastic being polypropylene.

[0060] Plastic materials generally include nonwoven materials, plastic films, rubber and the like.

[0061] The plastic material is preferably selected from the group consisting of: polyolefins (such as eg polyethylene, polypropylene...), polyesters (such as eg polyethylene terephthalate, polybutylene terephthalate), polyamides (such as eg 6-nylon, 6,6-nylon), poly(lactic acid) and mixtures thereof.

[0062] The backsheet preferably comprises a plastic film comprising a plastic material, and more particularly a plastic material selected from polyethylene.

[0063] The backsheet is preferably joined to the topsheet, absorbent core, or any other element of the disposable absorbent article by any attachment means known in the art. Suitable attachment means are, for example, a uniform continuous layer of adhesive, a patterned layer of adhesive, or an array of individual lines, spirals, or dots of adhesive.

[0064] The topsheet and the backsheet are preferably joined via a hot melt adhesive composition H as defined herein.

[0065] The backsheet may have a basis weight of 10 to 28 gsm, specifically 15 to 28 gsm, although other basis weights are possible.

[0066] Another layer

[0067] Disposable absorbent articles may also contain additional layers, such as acquisition layers, distribution layers, and mixtures thereof.

[0068] The function of the acquisition layer is generally to quickly draw fluid away from the topsheet to keep the skin dry.

[0069] The acquisition layer may typically be positioned between the topsheet and the absorbent core.

[0070] A typical example of an acquisition layer is a through-air bonded carded web, wherein the basis weight is in the range of 10 gsm to 60 gsm, as is known in the art.

[0071] The additional layers may be of any kind, such as nonwoven, woven material or loose fibers.

[0072] The further layers may comprise one or more plastic materials, which may be the same as or different from the plastic materials of the other layers.

[0073] Hot melt adhesive H

[0074] "Hot melt" means Adhesive The hot melt adhesive composition needs to be heated to at least 100° C., preferably at least 140° C., in order to be applied to the substrate. Therefore, the hot melt adhesive composition is solid at 23° C.

[0075] The hot melt adhesive composition H comprises:

[0076] at least one polymer P selected from the group consisting of polyolefins, thermoplastic block copolymers of vinyl-based aromatic hydrocarbons and conjugated diene compounds, and mixtures thereof;

[0077] At least one adhesion promoter T comprising at least one ester group or carboxylic acid group.

[0078] polyolefins

[0079] The polyolefin may be a homopolymer or a copolymer.

[0080] Polyolefins are well known in the adhesive art. They can be prepared using metallocene catalysts or Ziegler-Natta catalysts.

[0081] Olefins are unsaturated hydrocarbons, and the most typical monomers used in polyolefins are ethylene and α-olefins containing up to ten carbon atoms. Major olefin monomers include ethylene, propylene, butene-1,4-methylpentene, hexene, octene, and combinations thereof. Polyolefins include ethylene polymers, propylene polymers, and combinations thereof, including combinations with other α-olefins.

[0082] The propylene-based copolymer may comprise at least 50% propylene monomer, by weight of the copolymer.

[0083] The ethylene-based copolymer may comprise at least 50% ethylene monomer, by weight of the copolymer.

[0084] The remaining monomers can be other α-olefin monomers that may be present in the copolymer, such as 4-methyl-1-pentene, pentene-1, 2-methylpentene-1, 3-methylbutene-1, heptene-1, dimethylpentene-1, trimethylbutene-1, ethylpentene-1, methylpentene-1, trimethylpentene-1, methylethylpentene-1, 1-octene, diethylbutene-1, propylpentane-1, decene-1, methylnonene-1, nonene-1, trimethylheptene-1, methylethylbutene-1, dodecene-1, and hexadecene-1, and combinations thereof.

[0085] The exact monomer distribution is usually published by the supplier but can also be determined by suitable methods, such as nuclear magnetic resonance or infrared spectroscopy.

[0086] Suitable metallocene-catalyzed propylene-ethylene copolymers are commercially available from Clariant in the Licocene® polymer line in a wide range of properties, such as molecular weight, viscosity, crystallinity, etc.

[0087] Other suitable commercially available propylene-ethylene copolymers are available from Exxon as Vistamaxx® copolymers. Vistamaxx generally has a higher molecular weight than Licocene copolymers. Metallocene-catalyzed propylene homopolymers are available from Idemitsu Kosan Co., Ltd. under the tradename L-MODU™, particularly L-Modu S-410.

[0088] Thermoplastic block copolymers

[0089] The hot melt adhesive composition H preferably comprises one or more thermoplastic block copolymers of a vinyl-based aromatic hydrocarbon and a conjugated diene compound.

[0090] The "vinyl-based aromatic hydrocarbon" refers to an aromatic hydrocarbon compound having a vinyl group. Specific examples thereof include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, and vinylanthracene. In particular, styrene is preferred. These vinyl-based aromatic hydrocarbons may be used alone or in combination.

[0091] A "conjugated diene compound" refers to a diene compound having at least one pair of conjugated double bonds. Specific examples of "conjugated diene compounds" may include 1,3-butadiene, 2-methyl-1,3-butadiene (or isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. 1,3-butadiene and 2-methyl-1,3-butadiene are particularly preferred. These conjugated diene compounds may be used alone or in combination.

[0092] The thermoplastic block copolymer may be a non-hydrogenated or a hydrogenated thermoplastic block copolymer.

[0093] Specific examples of the “non-hydrogenated thermoplastic block copolymer” may include block copolymers in which the conjugated diene compound-based block is not hydrogenated. Specific examples of the “hydrogenated thermoplastic block copolymer” include block copolymers in which all or part of the conjugated diene compound-based block is hydrogenated.

[0094] Preferably, the thermoplastic block copolymer is a styrene-based block copolymer. A styrene-based block copolymer means a polymer having at least one styrene block. A styrene block means a segment comprising styrene as the main monomer, and preferably the segment is substantially composed only of styrene.

[0095] Specific examples of the “non-hydrogenated thermoplastic block copolymer” include styrene-isoprene-styrene block copolymer (also referred to as “SIS”) and styrene-butadiene-styrene block copolymer (also referred to as “SBS”). Specific examples of the “hydrogenated thermoplastic block copolymer (A)” include hydrogenated styrene-isoprene-styrene block copolymer (also referred to as “SEPS”), hydrogenated styrene-butadiene-styrene block copolymer (also referred to as “SEBS”) and styrene-butylene / butadiene-styrene block copolymer (also referred to as “SBBS”).

[0096] The thermoplastic block copolymer is preferably selected from a linear diblock copolymer having an AB structure (preferably a copolymer comprising one terminal styrene block and a block formed from at least one type of monomer other than a styrene monomer), a linear triblock copolymer having an ABA structure (preferably a copolymer comprising two terminal styrene blocks and a mid-chain ... (AB) structure n Y-structured star block copolymers and mixtures of these copolymers.

[0097] A represents a non-elastomeric polystyrene block.

[0098] B represents an elastomeric block polymer. B may notably be a polydiene, such as a polybutadiene and / or polyisoprene block.

[0099] Y represents a polyvalent compound.

[0100] Finally, n is an integer equal to at least 3.

[0101] Preferably, the thermoplastic block copolymer is selected from:

[0102] - styrene-butadiene-styrene copolymer (SBS),

[0103] - styrene-butadiene diblock (SB),

[0104] - styrene-isoprene-styrene copolymer (SIS),

[0105] - styrene-isoprene diblock (SI),

[0106] - styrene-ethylene-butylene-styrene copolymer (SEBS),

[0107] - styrene-propylene-butylene-styrene copolymer (SPBS),

[0108] - styrene-butadiene-butylene-styrene copolymer (SBBS),

[0109] - styrene-ethylene-propylene-styrene copolymer (SEPS),

[0110] - styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS),

[0111] - styrene-isoprene-butadiene-styrene copolymer (SIBS),

[0112] - styrene-isoprene-propylene-styrene copolymer (SIPS),

[0113] - styrene-farnesene copolymer (SFC),

[0114] - and any mixtures thereof.

[0115] The thermoplastic block copolymer preferably contains a styrene content in the range of 10% to 60% by mass.

[0116] Available commercial thermoplastic block copolymers include the KRATON D and G® series from Kraton Polymers, the EUROPRENE Sol T® series from Versalis (Eni group), the SOLPRENE® series from Dynasol Elastomers, the SINOPEC® series from SINOPEC, and the Taipol® and Vector® series from TSRC Corporation.

[0117] Other available instances include:

[0118] Sinopec® YH-1126, a linear SIS triblock copolymer with 16% styrene and 50% diblock content;

[0119] - Sinopec® YH-1209, a linear SIS triblock copolymer with 30% styrene content and less than 1% diblock content;

[0120] Kraton® D1152, a mixture of linear SBS triblock and SB diblock copolymers having a styrene content of 29.5% by weight, relative to the total weight of the mixture, an average molecular weight of about 122,000 g / mol, a melt flow index or MFI (measured in accordance with ISO 1133) of 8.5 g / 10 min at 200° C. under a load of 5 kg, and an SB diblock content of about 17% by weight, relative to the total weight of the mixture.

[0121] Kraton® D1161, a mixture of linear SIS triblock and SI diblock copolymers with a styrene content of 15% by weight, relative to the total weight of the mixture, an MFI (measured in accordance with ISO 1133) at 200° C. under a load of 5 kg of 9 g / 10 min, an average molecular weight of approximately 220 000 g / mol, and an SI diblock content of approximately 19% by weight, relative to the total weight of the mixture.

[0122] Taipol® SBS 4202 from TSRC Corporation, a linear SBS triblock copolymer with a styrene content of 40% by weight relative to the total weight of the triblock copolymer, an MFI (measured in accordance with ASTM D1238) of 3 to 10 g / 10 min at 190° C. under a load of 5 kg and an average molecular weight of about 102 400 g / mol.

[0123] Vector® 4411 from TSRC Corporation, a linear SIS triblock copolymer with a styrene content of 44% by weight, relative to the total weight of the triblock copolymer, an MFI (measured in accordance with ASTM D1238) of 40 g / 10 min at 200° C. under a load of 5 kg and an average molecular weight of about 106 000 g / mol.

[0124] More preferably, the hot melt adhesive composition H comprises

[0125] - a mixture of a linear triblock copolymer having an ABA structure and a linear diblock copolymer having an AB structure as defined above, more preferably a mixture of a SIS and a SI copolymer; or

[0126] - a linear triblock copolymer having an ABA structure, and more preferably a SIS copolymer.

[0127] The hot melt adhesive composition H may comprise 1-50 wt. %, preferably 5-40 wt. %, more preferably 10-40 wt. % of at least one polymer P (or a mixture of polymers P if multiple polymers P are present in the hot melt adhesive composition).

[0128] Tackifier T

[0129] As used herein, the terms "tackifier" and "tackifying resin" are used interchangeably.

[0130] The hot-melt adhesive composition H comprises at least one tackifier T which comprises at least one ester group or carboxylic acid group.

[0131] The tackifier T is preferably selected from:

[0132] - natural and modified rosins, for example gum rosin, wood rosin, tall oil rosin, distilled rosin, (partially or fully) hydrogenated rosin, dimerized rosin and polymerized rosin;

[0133] - Esters of natural and modified rosin,

[0134] - and mixtures thereof.

[0135] The esters of natural and modified rosins (including hydrogenated and non-hydrogenated rosins) are preferably ethylene glycol, glycerol or pentaerythritol esters of natural and modified rosins, for example glycerol esters of light wood rosin, glycerol esters of (partially or fully) hydrogenated rosin, glycerol esters of polymerized rosin, pentaerythritol esters of light wood rosin, pentaerythritol esters of (partially or fully) hydrogenated rosin, pentaerythritol esters of tall oil rosin and phenol-modified pentaerythritol esters of rosin.

[0136] The tackifier T may have a Ring and Ball softening point of 20° C. to 150° C., preferably 50° C. to 150° C. The softening point can be measured by using the ASTM E28 standard.

[0137] As examples of commercially available tackifier resins, mention may be made of: unmodified natural tall oil rosins sold under the trade name Sylvaros® (85, 90 and NCY) from Arizona Chemical Company, partially hydrogenated rosins sold under the trade name Foralyn® E from Eastman; fully hydrogenated rosins sold under the trade name Foral® AX-E from Eastman; fully hydrogenated rosins sold under the trade name Foral® DX from DRT; fully hydrogenated rosin esters sold under the trade name Foral® 105 from DRT, Sylvalite® RE 100L from Kraton (tall oil rosin ester based on pentaerythritol), Sylvalite® RE 85L sold by Kraton (glycerol ester of tall oil rosin), Sylvalite® 9000 sold by Kraton (tall oil rosin ester with an R&B softening point of 103° C.).

[0138] The hot melt adhesive composition H preferably contains 0.5 wt % to 70 wt %, more preferably 20 wt % to 70 wt %, even more preferably 20 wt % to 50 wt % of tackifier T (or a mixture of tackifiers T when multiple tackifier resins T are present in the hot melt adhesive composition H).

[0139] Other tackifiers T'

[0140] The hot melt adhesive composition H may further comprise a tackifier T′ which is different from the tackifier T defined above.

[0141] The tackifier T' is preferably selected from:

[0142] - aliphatic and cycloaliphatic petroleum hydrocarbon resins and their hydrogenated derivatives;

[0143] - aromatic petroleum hydrocarbon resins and their hydrogenated derivatives;

[0144] - aromatically modified aliphatic or cycloaliphatic petroleum hydrocarbon resins and their hydrogenated derivatives;

[0145] - polyterpene homopolymers, which can generally be produced by the polymerization of one or several terpene hydrocarbons (for example the monoterpene known as pinene), for example in the presence of a Friedel-Crafts catalyst;

[0146] - copolymers of terpenes and diene monomers (such as styrene, methylstyrene, etc.);

[0147] - phenol-modified terpene resins, such as those obtained by condensation of terpenes and phenols in acidic medium;

[0148] - and mixtures thereof.

[0149] Aliphatic petroleum hydrocarbon resins are generally produced by the polymerization of monomers consisting primarily of aliphatic olefins and diolefins. Aliphatic petroleum hydrocarbon resins and their hydrogenated derivatives may be based on C5 olefins, such as cis / trans 1,3-pentadiene, 2-methyl-2-butene.

[0150] Examples of aliphatic petroleum hydrocarbon resins (and hydrogenated derivatives) are those commercially available from Eastman Chemical Company under the tradename Eastotac® H100W (fully hydrogenated resin C5), or those commercially available under the tradename Eastotac® H100W (fully hydrogenated resin C5).

[0151] Cycloaliphatic petroleum hydrocarbon resins are generally produced by the polymerization of monomers consisting mainly of cycloaliphatic unsaturated hydrocarbons. They can be based on dicyclopentadiene or its derivatives (methyldicyclopentadiene, dimethyldicyclopentadiene, ...).

[0152] Aromatically modified aliphatic or cycloaliphatic petroleum hydrocarbon resins can be obtained from the copolymerization of aliphatic olefins (eg C5) or cycloaliphatic olefins with aromatic olefins (eg C9), optionally followed by partial or full hydrogenation.

[0153] Commercially available tackifiers T' are, for example, the polyterpene tackifiers sold under the trade names Sylvagum® TR and Sylvares® TR series (7115, 7125, A25L, B115, M1115) from Arizona Chemical Company; the polyterpene sold under the trade name DERCOLYTE® M 105 from DRT, which results from the polymerization of α-pinene and β-pinene and has a Ring and Ball softening point of 105° C., the terpene-phenol resins sold under the trade names Sylvares® TP (96, 2040, 300, 7042, 2019) from Arizona Chemical Company.

[0154] The hot melt adhesive composition H preferably contains 10% to 70% by weight, more preferably 10% to 40% by weight, and even more preferably 15% to 40% by weight of a tackifier T' (or a mixture of tackifiers T' in the case where multiple tackifier resins T' are present in the hot melt adhesive composition H) relative to the total weight of the hot melt.

[0155] Preferably, the hot melt adhesive composition H does not contain tackifying resins based on α-methylstyrene. Such tackifying resins are generally odorous and expensive.

[0156] Examples of tackifying resins based on alpha-methylstyrene are generally Kistalex 3085, Kristalex 1120 commercialized by Eastman Chemical.

[0157] plasticizers

[0158] Preferably, the hot melt adhesive composition comprises at least one plasticizer.

[0159] The plasticizer may be selected from naphthenic and paraffinic oils, liquid olefin polymers, plasticizers comprising at least one ester group or carboxylic acid group, and mixtures thereof.

[0160] Naphthenic oils and paraffinic oils are petroleum-based oils that involve mixtures of cycloalkanes (e.g., aliphatic saturated or unsaturated C4 to C7-membered hydrocarbon rings, preferably aliphatic saturated or unsaturated C4 to C6-membered rings, including cycloalkanes such as cyclopentane, cyclohexane, cycloheptane), paraffins (saturated linear or branched alkanes) and aromatic hydrocarbons (aromatic hydrocarbon rings, which may be monocyclic or polycyclic, and preferably aromatic C6-membered hydrocarbon rings).

[0161] The classification of naphthenic and paraffinic oils is based on the amount of each type of hydrocarbon in the oil. Typically, paraffinic oils have a chain hydrocarbon content of at least about 50% by weight; naphthenic oils have a cyclic hydrocarbon content of about 30% to about 50% by weight relative to the total weight of the plasticizer.

[0162] Examples of naphthenic oils are Nyflex® 223 and Nyflex® 222B commercialized by Nynas, or Primol® 352 and 382 from ExxonMobil.

[0163] The liquid olefin polymer may be selected from polypropylene, polybutene, hydrogenated polyisopropylene, hydrogenated butadiene, etc., and has an average molecular weight of about 100 to about 140,000 g / mol, preferably polyfarnesene having an average molecular weight greater than or equal to 135,000 g / mol.

[0164] The plasticizer comprising at least one ester group or carboxylic acid group is preferably selected from vegetable oils, animal oils and derivatives thereof.

[0165] Vegetable oils are compositions comprising triesters of fatty acids and glycerol (also known as "triglycerides").

[0166] The vegetable oil may be selected from castor oil, sunflower oil, coconut oil, corn oil, canola oil, olive oil, palm oil, cottonseed oil, rapeseed oil, safflower oil, soybean oil, sesame oil, olive oil, almond oil, avocado oil, hemp oil, linseed oil, and mixtures thereof.

[0167] The fatty acids may be hydrogenated or non-hydrogenated fatty acids.

[0168] The fatty acid may be selected from the group consisting of myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and ricinoleic acid.

[0169] The derivatives of vegetable oils may be esterified fatty acids, fatty acid oligomers / polymers and mixtures thereof.

[0170] The esterified fatty acid can be produced by a transesterification reaction between a monohydric alcohol (preferably with a low molecular weight) and a triglyceride. In this case, the monohydric alcohol is preferably selected from methanol, ethanol, propanol, isopropanol, butanol and 2-ethylhexanol.

[0171] An example of the esterified fatty acid produced by the transesterification reaction between monohydric alcohol and triglyceride may be the commercially available RADIA 7916 commercialized by OLEON.

[0172] Esterified fatty acids can also be produced by a transesterification reaction between a polyol and a triglyceride. In this case, the polyol can be selected from glycerol and pentaerythritol. Examples of esterified fatty acids produced by a transesterification reaction between a polyol and a triglyceride can be the commercially available PIONIER® TP130S from H&R (which is a hydrogenated esterified soybean oil) and the commercially available RADIA 7176 (pentaerythritol tetrastearate) commercialized by OLEON.

[0173] Fatty acid oligomers / polymers can be produced from:

[0174] - polycondensation of a fatty acid or a mixture of fatty acids;

[0175] -Polycondensation of vegetable oil with a fatty acid.

[0176] Preferably, the fatty acid oligomer / polymer is a ricinoleic acid oligomer / polymer obtained by polycondensation of ricinoleic acid.

[0177] An example of a fatty acid oligomer / polymer resulting from the polycondensation of a vegetable oil with a fatty acid is Crodabond SA (acid value = 1 mg KOH / g) commercialized by CRODA.

[0178] Preferably, the plasticizer has an acid value lower than or equal to 10 mg KOH / g.

[0179] Preferably, the plasticizer is selected from fatty acid oligomers / polymers.

[0180] The hot melt adhesive composition H preferably comprises 0 to 50 wt %, more preferably 1 to 40 wt %, even more preferably 5 to 20 wt % of plasticizer relative to the total weight of the hot melt.

[0181] wax

[0182] The hot melt adhesive composition may further comprise a wax.

[0183] The wax may be present in the hot-melt adhesive composition H in an amount of 0% to 40% by weight, and preferably 5% to 30% by weight, relative to the total weight of the hot-melt adhesive composition.

[0184] Waxes typically include microcrystalline waxes, paraffin waxes, polyethylene waxes, polypropylene waxes, by-product polyethylene waxes, and Fischer-Tropsch waxes.

[0185] Examples of Fischer-Tropsch waxes are available from Sasol-SA under the tradenames PARAFLINT® H-1, H-4 and H-8, and from Shell under the tradename GTL Sarawax.

[0186] additive

[0187] The hot melt adhesive composition of the present invention may optionally include one or more additives. Such additives may include waxes, antioxidants, pigments, brighteners, colorants, fluorescent agents, dyes, fillers, flow and leveling agents, wetting agents, surfactants, defoamers, rheology modifiers, emulsifiers, humectants, gelling agents, colorants, other surface modifiers, fragrances, and penetration enhancers.

[0188] Additives may be incorporated into the hot-melt adhesive composition H in small amounts, for example up to about 10% by weight, preferably up to 5% by weight.

[0189] Useful antioxidants may include, for example, pentaerythritol tetrakis[3,(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis(4-methyl-6-tert-butylphenol), phosphites (including, for example, tris-(p-nonylphenyl)-phosphite (TNPP) and bis(2,4-di-tert-butylphenyl) 4,4'-diphenylene-diphosphonite), di-stearyl-3,3'-thiodipropionate (DSTDP), and combinations thereof.

[0190] Useful antioxidants are commercially available under various trade names, including, for example, the IRGANOX series, including IRGANOX 1010, IRGANOX 565, and IRGANOX 1076 hindered phenol antioxidants and IRGAFOS 168 phosphite antioxidant, all available from BASF Corporation, and ETHYL 702 4,4'-methylenebis(2,6-di-tert-butylphenol).

[0191] Preparation of hot melt adhesive

[0192] The hot melt adhesive composition H can be prepared by mixing the polymer P with the tackifier resin, optionally the plasticizer and any other additional compounds, and then heating the mixture at a temperature of 100 to 180° C. for a duration of 1 to 8 hours.

[0193] Alternatively, the hot melt adhesive composition H can be prepared by heating a mixture of polymer P, optional plasticizer and any other additional compounds at a temperature of 100 to 180° C. for a duration of 1 to 8 hours and then adding the tackifier resin.

[0194] The composition may then be cooled at a temperature of 20 to 30°C, and preferably at a temperature of about 23°C (ambient temperature).

[0195] The hot-melt adhesive composition H is preferably not a hot-melt pressure-sensitive adhesive.

[0196] The hot melt adhesive composition H preferably comprises:

[0197] 5 to 40 wt% of a thermoplastic block copolymer of a vinyl-based aromatic hydrocarbon and a conjugated diene compound, and mixtures thereof;

[0198] 20% to 70% by weight of a tackifier T comprising at least one ester group or carboxylic acid group;

[0199] 1 to 40 wt% of a plasticizer selected from vegetable oils, animal oils and their derivatives.

[0200] The viscosity of the hot melt adhesive composition H at 149° C. is preferably in the range of 200 to 15,000 mPa·s, more preferably in the range of 300 to 13,000 mPa·s, and even more preferably in the range of 300 to 5,000 mPa·s. The viscosity is measured using ASTM method D-3236.

[0201] The hot melt adhesive composition H preferably has a Ring and Ball softening point of 50° C. to 120° C., preferably 65° C. to 100° C. The softening point can be measured by using the ASTM E28 standard.

[0202] When the adhesive coating weight is 5g / m 2In the case of the hot melt adhesive composition H, the hot melt adhesive composition H preferably exhibits an average initial dry peel strength higher than 2.0 N / 25 mm, more preferably higher than 2.0 N / 25 mm, and even more preferably higher than 2.5 N / 25 mm. The average initial dry peel strength is measured according to the method described below entitled "Initial Dry Peel Measured at 23°C". The "Initial Dry Peel Strength" is generally the dry peel strength of the hot melt adhesive composition before the washing conditions of the recycling process.

[0203] When the adhesive coating weight is 5g / m 2 In the case of the hot melt adhesive composition H, the hot melt adhesive composition H preferably exhibits an average initial wet peel strength higher than 2.0 N / 25 mm, more preferably higher than 2.0 N / 25 mm, and even more preferably higher than 2.5 N / 25 mm. The average wet peel strength is measured according to the method described below entitled "Initial wet peel measured at 23°C". The "initial wet peel strength" is generally the wet peel strength of the hot melt adhesive composition before the washing conditions of the recycling process.

[0204] Method-Steps

[0205] The present invention relates to a method for recycling plastic materials from post-consumer disposable absorbent articles comprising a topsheet, a backsheet, an absorbent core, a hot melt adhesive H, as defined herein, wherein at least one of the topsheet and the backsheet comprises at least one plastic material,

[0206] The method is characterized in that the method comprises:

[0207] - step i): providing a post-consumer disposable absorbent article,

[0208] - step ii): immersing the post-consumer disposable absorbent article in an alkaline aqueous solution under conditions sufficient to obtain debonding of the plastic material,

[0209] - Step iii): separation and recovery of the plastic material from the medium.

[0210] Step ii)

[0211] The post-consumer disposable absorbent article of step ii) has advantageously not been subjected to a shredding step / crushing step and is used as is (not broken into pieces).

[0212] The alkaline aqueous solution used herein has a pH greater than 7.

[0213] The alkaline aqueous solution is preferably an aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide, or a mixture thereof.

[0214] The concentration of hydroxide ions in the alkaline solution may be 1% to 10% by weight, preferably 1% to 5% by weight.

[0215] More preferably, the alkaline aqueous solution is an aqueous solution of sodium hydroxide.

[0216] The pH of the alkaline aqueous solution is preferably in the range of 8 to 14, more preferably 10 to 14.

[0217] The pH of the alkaline aqueous solution can be measured according to a known method, for example, using a pH meter.

[0218] Conditions sufficient to obtain debonding of the plastic material are preferably:

[0219] - at a temperature below the softening temperature of the hot-melt adhesive composition H,

[0220] - for a period ranging from 10 seconds to 24 hours, preferably from 10 seconds to 6 hours.

[0221] More preferably, the conditions sufficient to obtain debonding of the plastic material are:

[0222] - at temperatures ranging from 23°C to 80°C,

[0223] - Lasts for a time range of 10 seconds to 2 hours.

[0224] Even more preferably, the conditions sufficient to obtain debonding of the plastic material are:

[0225] - at temperatures ranging from 30°C to 80°C,

[0226] - Lasts for a time range of 10 seconds to 15 minutes.

[0227] Step ii) is preferably carried out with mixing, for example with a mixer or mechanical stirrer.

[0228] Step ii) advantageously allows the plastics material to be debonded until complete separation (eg without additional mechanical peeling).

[0229] Step ii) advantageously allows debonding of the plastic material from other materials (such as cotton, natural fibers, fluff, . . . ) present in the post-consumer disposable absorbent article, more particularly until the plastic material is completely separated from said other materials.

[0230] During step ii), the adhesive properties, such as adhesion, of the adhesive layer produced by the hot melt adhesive composition H are advantageously reduced. When the post-consumer disposable absorbent article is subjected to step ii), the peel adhesion may be reduced by at least 80% or even at least 90%, and preferably at least 99%.

[0231] More preferably, when the post-consumer disposable absorbent article comprises at least two different plastic materials, step ii) advantageously allows the two different plastic materials to be debonded from each other. These at least two different plastic materials may be included in the same layer, for example in the topsheet, or may be included in separate layers, for example one plastic material in the topsheet and a different plastic material in the backsheet, or each of the topsheet and the backsheet may comprise two or more different plastic materials.

[0232] During step ii), the hot-melt adhesive composition H present in the (post-consumer) disposable absorbent article (more particularly as an adhesive layer) advantageously loses its adhesive properties to a certain extent under conditions enabling debonding of the plastic material in contact with said hot-melt adhesive composition H / adhesive layer.

[0233] Preferably, less than 20% by weight, even more preferably less than 10% by weight, and even more advantageously less than 1% by weight of the hot-melt adhesive composition H is dissolved in the alkaline aqueous solution. Consequently, the adhesive residue in the medium resulting from step ii) is advantageously less than 20% by weight, preferably less than 10% by weight, and even more preferably less than 1% by weight. This advantageously allows additional decontamination treatment of the washing solution to be avoided.

[0234] Advantageously, the hot-melt adhesive composition H remains predominantly on the debonded plastic material. Preferably, more than 80% by weight of the hot-melt adhesive composition H remains on the debonded plastic material.

[0235] Step iii)

[0236] The method according to the invention comprises a step iii) of separating and recovering the plastic material from the medium.

[0237] The medium of step iii) is preferably the alkaline aqueous solution obtained after step ii). It may contain any layer components and / or any contaminants that are typically soluble in alkaline aqueous solutions. The medium advantageously contains less than 20% by weight, more preferably less than 10% by weight, and even more preferably less than 1% by weight of the hot melt adhesive composition H.

[0238] The separation step iii) can be performed by suitable mechanical means, for example by filtration, by sedimentation, by decantation, by centrifugation.

[0239] In a preferred embodiment, at least one of the topsheet and the bottomsheet comprises at least two different plastic materials. According to this embodiment, step iii) may allow:

[0240] - separation and recovery of the mixture of plastic materials from the medium (which may be followed by an additional step of sorting the plastic materials based on differences in their chemical properties); or

[0241] - Separation and recovery of the individual plastic materials from the medium in isolation (avoiding mixtures of different plastic materials). For example, if the topsheet comprises polypropylene as the first plastic material and the bottomsheet comprises polyethylene as the second plastic material, step iii) advantageously allows the individual polypropylene to be separated and recovered, as well as the individual polyethylene to be recovered. This separation can be performed by gravimetric techniques (depending on the density of each plastic material).

[0242] Preferably, the present invention relates to a method for recycling plastic material from post-consumer disposable absorbent articles comprising a topsheet, a backsheet, an absorbent core, a hot melt adhesive H, as defined herein, wherein at least one of the topsheet and the backsheet comprises at least two different plastic materials,

[0243] The method is characterized in that the method comprises:

[0244] - step i): providing a post-consumer disposable absorbent article,

[0245] - step ii): immersing the post-consumer disposable absorbent article in an alkaline aqueous solution under conditions sufficient to obtain debonding of the at least two plastic materials,

[0246] - Step iii): separation and recovery of said at least two different plastic materials from said medium, allowing separate sorting and recovery of each individual plastic material.

[0247] Additional steps

[0248] The method according to the present invention may further comprise a rinsing step iv) of the plastic material recovered after step iii).

[0249] The rinsing step iv) may last from 2 to 60 minutes, preferably from 5 to 50 minutes.

[0250] The rinsing step iv) can be carried out with water or an organic solvent.

[0251] The amount of water or the organic solvent used in step iv) may be in the range of 500 to 5000 parts by mass relative to 100 parts by mass of the plastic material.

[0252] When step iv) is carried out with water, the method according to the present invention may further comprise a step v) of dehydrating the plastic material recovered after step iii) and / or step iv).

[0253] The dehydration step v) can be performed using a dehydrator.

[0254] The dehydration step v) may last from 1 to 15 minutes.

[0255] Preferably, the method as defined herein further comprises a drying step vi) of the plastic material recovered in step iii), step iv) or step v).

[0256] The drying step can be performed using a drying device or a hot air dryer.

[0257] The drying conditions may not be particularly limited as long as they allow sufficient drying of the recycled plastic material. For example, the drying temperature may range from 80° C. to 200° C., more preferably from 100° C. to 150° C. The drying time may range from 10 to 240 minutes.

[0258] The recycled plastic material (recovered from step iii) or step iv) or step v)) is preferably subjected to a sterilization treatment.

[0259] The recycled plastic material is advantageously subjected to a pelletizing step for reuse in plastic processing, for example in injection molding.

[0260] In the case where the post-consumer disposable absorbent article contains superabsorbent polymer in the absorbent core, the method of the present invention may further comprise a step of recovering the superabsorbent polymer (SAP) from the medium. This step may be performed by suitable mechanical means, such as by filtration. This optional step may be performed after step iii).

[0261] The recovered superabsorbent polymer (SAP) may be subjected to further purification steps.

[0262] Preferably, in the process of the present invention, the post-consumer disposable absorbent article is not subjected to ozone treatment and / or acid treatment prior to step ii).

[0263] Preferably, the process of the present invention does not comprise an extraction step with a solvent prior to step ii) (meaning no solvent is added to the post-consumer disposable absorbent article).

[0264] Preferably, the process of the present invention does not comprise a step of shredding the post-consumer disposable absorbent articles (which are not in the form of fragments) prior to step ii).

[0265] The method for recycling plastic material advantageously allows for the recycling of the recovered plastic material.

[0266] The method according to the present invention advantageously allows debonding, separation and recovery of high-quality plastic materials from post-consumer disposable absorbent articles.The method is advantageously easy to implement, efficient, economical and smooth.

[0267] The present invention also relates to a method for recycling post-consumer disposable absorbent articles comprising a topsheet, a backsheet, an absorbent core, a hot melt adhesive H, as defined herein, wherein at least one of the topsheet and the backsheet comprises at least one plastic material,

[0268] The method is characterized in that the method comprises:

[0269] - step i): providing a post-consumer disposable absorbent article,

[0270] - step ii): immersing the post-consumer disposable absorbent article in an alkaline aqueous solution under conditions sufficient to obtain debonding of the plastic material,

[0271] - Step iii): separating the plastic material from the medium into reusable raw materials.

[0272] The definitions, descriptions, embodiments and preferred embodiments of the post-consumer absorbent article, topsheet, backsheet, hot melt adhesive H step in the method for recycling plastic materials disclosed above are applicable to the method for recycling without repeating them.

[0273] B. Recycled / recovered plastic materials

[0274] The present invention also relates to recycled plastic material obtained by the recycling method disclosed herein.

[0275] Recycled plastic material preferably means less than 10% by weight of hot-melt adhesive residues.

[0276] The recycled plastic material can be converted into films or pellets for advantageous subsequent reuse.

[0277] The ranges disclosed in this specification include their lower and upper limits. For example, the expression "range (from) x to y (range (from) x to y)" or "between x and y" includes the limits x and y. Example

[0278] The following examples illustrate the present invention without limiting it.

[0279] Description of raw materials:

[0280] The materials used are as follows:

[0281] - Nyflex 223 (from NYNAS): a hydrotreated naphthenic process oil commercialized by Ergon (acid and hydroxyl values ​​below 1 mg KOH / g)

[0282] - Polyester A from VANDEPUTTE: Bio-based oligoester made from pure ricinoleic acid by polycondensation (acid value = 7 mg KOH / g and hydroxyl value = 25 mg KOH / g)

[0283] - Crodabond CSA (from CRODA): a bio-based oligoester made by polycondensation of castor oil and sebacic acid (acid value less than 1 mg KOH / g, hydroxyl value = 55 mg KOH / g)

[0284] - Escorez 5400 (from EXXON): Hydrogenated hydrocarbon DCPD resin with an R&B softening point of 101°C (acid and hydroxyl values ​​less than 1 mg KOH / g)

[0285] - Sylvalite 9000: a tall oil rosin ester commercialized by KRATON with a ring and ball softening point of approximately 105°C and a renewable carbon content of 97%;

[0286] - Dercolyte® M105: a polyterpene resin commercialized by DRT resulting from the polymerization of α-pinene and β-pinene and having a Ring and Ball softening point of 105°C

[0287] -Foral DX (from PINOVA): Hydrogenated rosin resin with an R&B softening point of 70°C (acid value less than 158 mgKOH / g and hydroxyl value less than 1 mgKOH / g)

[0288] - Irganox 1010: a phenolic antioxidant commercialized by BASF;

[0289] - SINOPEC® YH-1209 (from SINOPEC) is a linear SIS with 30% styrene and less than 1% diblock;

[0290] - SINOPEC® YH-1126 (from SINOPEC) is a linear SIS copolymer with 16% styrene and 50% diblock content.

[0291] Brookfield viscosity:

[0292] Brookfield viscosity is measured according to standard method ASTM D-3236 using a Spindle Model 27 Brookfield Viscometer at a temperature of about 149°C.

[0293] Global Softening Point

[0294] It is measured according to the standard method EN 1427 and corresponds to the temperature at which a disk of material held in a ring and loaded with balls will flow over a certain distance when heated in glycerol.

[0295] Acid value

[0296] It is given by the supplier and determined by the standard method ASTM D1980.

[0297] Hydroxyl value

[0298] It is given by the supplier and determined by standard method ASTM E1899-16.

[0299] Example 1: Preparation of hot melt adhesive

[0300] The composition of Example 1 in Table 1 was prepared by simply mixing its ingredients. The polymer and antioxidant were heated and melted at 150°C until all dissolved into a homogeneous mixture. The resin was then added at the same temperature until all dissolved into a homogeneous mixture. Finally, the mixture was cooled and collected for use as is.

[0301] Compositions A, B, C (invention) and D (comparative) in the following table are compositions according to the invention.

[0302] Table 1: Hot melt adhesive composition

[0303]

[0304] Example 2 : Preparation of laminates by slit nozzle coating equipment

[0305] The laminate was prepared as follows:

[0306] As laminating device, a machine operating continuously at a line speed of approximately 200 m / min, which is sold under the name Coater CTL 4400 by NORDSON, was used.

[0307] In this machine, the coating nozzle is a slot nozzle, NORDSON Slot™.

[0308] The two substrates used are:

[0309] - 22g / m² PE breathable membrane with a width of 20 cm, and

[0310] -15 g / m² of the same width 2 Spunbond hydrophilic nonwoven sheet composed of fibers of polypropylene (PP).

[0311] The two substrates were packaged into rolls with a width of 20 cm.

[0312] The hot melt adhesive composition of Table 1 was heated in a melting pot at a temperature of 150°C.

[0313] Then it was heated at the same temperature of 150℃ with a temperature of about 5 g / m 2 The coating weight is coated on the PE film.

[0314] The resulting coating patterns are very conformable and typically have good processability.

[0315] The nonwoven (PP) sheet was then brought into contact with the coated surface of the PE film by means of a press roller applying a pressure of 1 bar.

[0316] Example 3: performance

[0317] The laminate obtained in Example 2 was then packaged into a roll and placed at ambient temperature (23° C.) and 50% relative humidity for 24 hours.

[0318] Rectangular strips measuring 2.54 cm by approximately 10 cm were then cut out of the coated center area of ​​the laminate.

[0319] Dry peel measurement

[0320] The two separate substrates were separated, starting from one end of the above rectangular strip (as the test specimen) and extending over approximately 2 cm.

[0321] The two free ends thus obtained are fixed to two clamping devices respectively connected to the stationary and movable parts of the tensile testing device, said stationary and movable parts being situated on a vertical axis.

[0322] When the driving mechanism transmits a uniform speed of 300 mm / min to the movable part, resulting in the separation of the two substrates, the separated ends of the two substrates gradually displace along the vertical axis while forming an angle of 180°. The stationary part connected to the dynamometer measures the force exerted on the specimen thus held.

[0323] The results corresponding to peeling after 24 hours at 23° C. are expressed in N / 25 mm.

[0324] The results are reported in Table 2 below.

[0325] Wet peeling measurement

[0326] The rectangular strips were completely immersed in a 30°C deionized water bath for 30 seconds, then removed and dried. The same protocol as for the "dry peel measurement" was applied to determine the peel strength after wet conditioning.

[0327] The results are also reported in Table 2 below.

[0328] Treatment method (washing soda solution)

[0329] The rectangular strips were completely immersed in a 2 wt % NaOH solution bath at 30° C. for 30 seconds (under mixing: 300 rpm), then taken out with a jig and dried.

[0330] The same protocol as for the "Dry Peel Measurement" was applied to determine the peel strength after the treatment method (NaOH).

[0331] The results are reported in Table 2 below.

[0332] Table 2: Performance

[0333]

[0334] The table shows that the use of hot-melt adhesive compositions A, B, and C (according to the invention) advantageously allows debonding of the two substrates mentioned above. In fact, the dry peel after the treatment according to the invention is advantageously low, even equal to zero. After only 30 seconds of treatment, there is at least 85% loss of adhesion (dry peel) for compositions B and C, and more than 95% loss of adhesion for compositions A and C. This is not the case with comparative example D, where the dry peel is not reduced after the treatment according to the invention.

Claims

1. A method for recycling plastic materials from post-consumer disposable absorbent articles, the post-consumer disposable absorbent articles comprising a topsheet, a backsheet, an absorbent core, a hot melt adhesive composition H, wherein at least one of the topsheet and the backsheet comprises at least one plastic material, The hot melt adhesive composition H comprises: at least one polymer P selected from the group consisting of polyolefins, thermoplastic block copolymers of vinyl-based aromatic hydrocarbons and conjugated diene compounds, and mixtures thereof; at least one tackifier T comprising at least one ester group or carboxylic acid group; The method is characterized in that the method comprises: - step i): providing a post-consumer disposable absorbent article, - step ii): immersing the post-consumer disposable absorbent article in an alkaline aqueous solution under conditions sufficient to obtain debonding of the plastic material, - Step iii): separation and recovery of the plastic material from the medium.

2. The method according to claim 1, wherein the plastic material is selected from the group consisting of: polyolefins (e.g. polyethylene, polypropylene, ...), polyesters (e.g. polyethylene terephthalate, polybutylene terephthalate), polyamides (e.g. 6-nylon, 6,6-nylon), poly(lactic acid) and mixtures thereof.

3. The method according to any one of claims 1 to 2, wherein The topsheet comprises a nonwoven material, preferably comprising a plastic material, even more preferably the topsheet comprises a nonwoven material comprising polypropylene.

4. The method according to any one of claims 1 to 3, wherein the bottom sheet comprises a plastic film comprising a plastic material, and more particularly a plastic material chosen from polyethylene. 5 . The method according to claim 1 , wherein the hot melt adhesive composition H comprises one or more thermoplastic block copolymers of a vinyl-based aromatic hydrocarbon and a conjugated diene compound.

6. The method according to any one of claims 1 to 5, wherein the thermoplastic block copolymer is selected from: - styrene-butadiene-styrene copolymer (SBS), - styrene-butadiene diblock (SB), - styrene-isoprene-styrene copolymer (SIS), - styrene-isoprene diblock (SI), - styrene-ethylene-butylene-styrene copolymer (SEBS), - styrene-propylene-butylene-styrene copolymer (SPBS), - styrene-butadiene-butylene-styrene copolymer (SBBS), - styrene-ethylene-propylene-styrene copolymer (SEPS), - styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS), - styrene-isoprene-butadiene-styrene copolymer (SIBS), - styrene-isoprene-propylene-styrene copolymer (SIPS), - styrene-farnesene copolymer (SFC), - and any mixtures thereof.

7. The method according to any one of claims 1 to 6, wherein the hot melt adhesive composition H comprises at least one plasticizer, preferably selected from naphthenic and paraffinic oils, liquid olefin polymers, plasticizers comprising at least one ester group or carboxylic acid group, and mixtures thereof, even more preferably selected from fatty acid oligomers / polymers.

8. The method according to any one of claims 1 to 7, wherein the adhesive coating weight is 5 g / m 2 In the case of the above, the hot melt adhesive composition H exhibits an average initial dry peel strength higher than 2.0 N / 25 mm, more preferably higher than 2.0 N / 25 mm, even more preferably higher than 2.5 N / 25 mm.

9. The method according to any one of claims 1 to 8, wherein the adhesive coating weight is 5 g / m 2 In the case of the above, the hot melt adhesive composition H exhibits an average initial wet peel strength higher than 2.0 N / 25 mm, more preferably higher than 2.0 N / 25 mm, even more preferably higher than 2.5 N / 25 mm.

10. The method according to any one of claims 1 to 9, wherein in step ii), the alkaline aqueous solution is an aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide and mixtures thereof, preferably the alkaline aqueous solution is an aqueous solution of sodium hydroxide.

11. The method according to any one of claims 1 to 10, wherein in step ii), the concentration of hydroxide ions in the alkaline solution is in the range of 1% to 10% by weight, preferably 1% to 5% by weight.

12. The process according to any one of claims 1 to 11, wherein in step ii), the pH of the alkaline aqueous solution is in the range of 8 to 14, more preferably 10 to 14.

13. The method according to any one of claims 1 to 12, wherein In step ii), the conditions sufficient to obtain debonding of the plastic material are: - at a temperature below the softening temperature of the hot-melt adhesive composition H, - for a period of time ranging from 10 seconds to 24 hours, preferably from 10 seconds to 6 hours.

14. The method according to any one of claims 1 to 13, wherein At least one of the topsheet and the backsheet comprises at least two different plastic materials, the method being characterized in that the method preferably comprises: - step i): providing a post-consumer disposable absorbent article, - step ii): immersing the post-consumer disposable absorbent article in an alkaline aqueous solution under conditions sufficient to obtain debonding of the at least two plastic materials, - Step iii): separation and recovery of said at least two different plastic materials from said medium, allowing separate sorting and recovery of each individual plastic material.

15. The method according to any one of claims 1 to 14, wherein the post-consumer disposable absorbent article is not subjected to ozone treatment and / or acid treatment prior to step ii).

16. The method according to any one of claims 1 to 15, characterized in that The method does not comprise a step of shredding the post-consumer disposable absorbent articles prior to step ii).

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