Hot melt composition

Abstract

The invention relates to a hot melt composition comprising:-at least one styrenic block copolymer,-at least one tackifying resin, and-at least one acid-modified glyceride. The invention also relates to the use of the hot-melt composition according to the invention, to a method for bonding substrates using the hot-melt composition according to the invention, and to an article or multilayer system comprising the hot-melt composition according to the invention. The invention also relates to a self-adhesive product obtainable from a multilayer system according to the invention. In addition, the invention relates to the use of acid-modified glycerides for reducing the adhesion of a hot melt composition when said composition is immersed in a hot aqueous alkaline solution. Finally, the invention relates to a method for recovering an article comprising a hot melt composition according to the invention.

Description

Technical Field The present invention relates to hot melt compositions and their use, methods for bonding substrates, articles, multilayer systems, self-adhesive products, uses of acid-modified glycerides, and methods for recycling articles. Technical Background Hot melt compositions (HM compositions) are substances that are solid at room temperature and generally contain neither water nor solvent. They are generally used as adhesives.

[0001] Among these HM compositions, hot melt pressure sensitive adhesives (HMPSA) are substances that impart instant adhesive properties (also called "tack") to substrates coated with such adhesives, which allow the substrate to bond instantly to another substrate under slight and brief pressure at room temperature (e.g., between 18° C. and 25° C.).

[0002] HM adhesives are usually applied in a molten state after heating to a temperature, most often between 140° C. and 190° C., and solidify during cooling. Non-HMPSA HM adhesives thus form a seal (or adhesive joint) after cooling that ensures adhesion of the substrates to be assembled, whereas HMPSAs adhere the substrates at room temperature under slight and brief pressure.

[0003] HM adhesives are widely used in various applications. In particular, non-HMPSA HM adhesives can be used in nonwoven applications (e.g., disposable hygiene and medical products), and HMPSA can be used in nonwoven applications or in the manufacture of self-adhesive labels attached to articles or in the manufacture of self-adhesive tapes (e.g., transparent adhesive tapes, tapes for forming and assembling cardboard packaging, tapes for surface protection in painting operations, tapes for cable maintenance, double-sided adhesive tapes).

[0004] Many articles are subjected to recycling processes for the purpose of reusing them (e.g., reusing a glass bottle after removing a label adhered thereto) or for the purpose of recovering their constituent materials after destruction. Such processes require the separation of the adhered substrates contained in the article.

[0005] These recovery treatments may include a step of immersing the article in an alkaline aqueous solution maintained at a temperature between 60° C. and 100° C. The purpose of such a step is to debond the bonded substrates of the article.

[0006] An object of the present invention is to provide a hot-melt composition having reduced adhesion after immersion in a hot alkaline aqueous solution, so that articles containing the composition can be more easily recovered. In particular, substrates bonded with the composition can be easily separated after immersion in a hot alkaline aqueous solution. SUMMARY OF THE INVENTION The present invention relates to a hot melt composition comprising: - at least one styrene block copolymer, - at least one tackifying resin, and - at least one acid-modified glyceride.

[0008] The invention also relates to the use of the hot-melt composition according to the invention as an adhesive or as an alkali-debondable adhesive.

[0009] Furthermore, the present invention relates to a method for bonding substrates, comprising: - heating the hot melt composition according to the invention for at least a period of time sufficient to render the composition sufficiently liquid to be applied to a substrate, and then - coating the composition on the surface of a first substrate, and then - contacting the coated surface of the first substrate with the surface of the second substrate so as to form a bonded joint bonding the two substrates.

[0010] The present invention further relates to an article or a multilayer system, both comprising the hot-melt composition according to the invention.

[0011] The invention also relates to self-adhesive products obtainable from the multilayer system according to the invention.

[0012] Furthermore, the present invention relates to the use of acid-modified glycerides for reducing the adhesion of hot-melt compositions when said compositions are immersed in a hot alkaline aqueous solution.

[0013] Finally, the present invention relates to a process for recycling an article comprising a hot-melt composition according to the invention, said composition bonding at least two substrates of the article, comprising a step of immersing the article in a hot alkaline aqueous solution and a step of debonding the substrates bonded by the hot-melt composition.

[0014] The present invention makes it possible to address the needs mentioned above. In particular, the hot-melt composition according to the invention surprisingly has a significantly reduced adhesion after immersion in a hot aqueous alkaline solution.

[0015] The present invention thus makes it possible to provide articles comprising a hot-melt composition according to the invention which can be easily recovered after being immersed in a hot aqueous alkaline solution.

[0016] Description of the Invention The present invention relates to a hot melt composition comprising: - at least one styrene block copolymer, - at least one tackifying resin, and - at least one acid-modified glyceride.

[0017] Hot melt composition The term "hot melt" is used herein to describe a composition that is solid at ambient temperature (e.g., 18°C-25°C) and needs to be heated to melt and then applied to a substrate. The composition according to the present invention is typically molten at a temperature of at least 120°C (preferably at least 130°C).

[0018] Styrene block copolymer The hot-melt composition according to the invention comprises at least one styrene block copolymer.

[0019] By "styrene block copolymer" is meant a block copolymer comprising at least one polystyrene block. Preferably, the styrene block copolymer is a linear block copolymer or a radial block copolymer comprising at least one non-elastomeric block A which is a polystyrene block and at least one elastomeric block B which is a fully or partially hydrogenated or non-hydrogenated diene polymer block.

[0020] Advantageously, the at least one styrenic block copolymer comprises SB, SI, SEB, SEP, SBBS, SBS, SEBS, SEPS, SEEPS, SIBS and / or SIS.

[0021] By "SB" is meant styrene-butadiene block copolymer.

[0022] By "SI" is meant styrene-isoprene block copolymer.

[0023] By "SEB" is meant styrene-ethylene-butylene block copolymer.

[0024] By "SEP" is meant styrene-ethylene-propylene block copolymer.

[0025] By "SBBS" is meant styrene-butadiene-butylene-styrene block copolymer.

[0026] By "SBS" is meant styrene-butadiene-styrene block copolymer.

[0027] By "SEBS" is meant styrene-ethylene-butylene-styrene block copolymer or styrene-ethylene / butylene-styrene block copolymer.

[0028] By "SEPS" is meant styrene-ethylene-propylene-styrene block copolymers.

[0029] By "SEEPS" is meant styrene-ethylene-ethylene-propylene-styrene block copolymers.

[0030] By "SIBS" is meant styrene-isoprene-butadiene-styrene block copolymer.

[0031] By "SIS" is meant styrene-isoprene-styrene block copolymer.

[0032] Preferably, the at least one styrenic block copolymer comprises SBBS, SBS, SEBS, SEPS, SEEPS, SIBS and / or SIS.

[0033] More preferably, the at least one styrenic block copolymer comprises SBS, SEBS and / or SIS.

[0034] Styrene triblock copolymers can be obtained using methods known per se and are commercially available. The method for obtaining these commercial products can result in the formation of a variable amount of diblock compounds of formula AB. Therefore, when at least one styrene block copolymer includes (especially as described above) triblock copolymer, relative to the total weight of the styrene block copolymer, it may further include a diblock compound between 0 weight % and 90 weight %. Similarly, when at least one styrene block copolymer includes (especially as described above) tetrablock copolymer, relative to the total weight of the styrene block copolymer, it may further include a diblock compound and / or triblock compound between 0 weight % and 90 weight %. In addition, when at least one styrene block copolymer includes (especially as described above) pentablock copolymer, relative to the total weight of the styrene block copolymer, it may further include a diblock compound, triblock compound and / or tetrablock compound between 0 weight % and 90 weight %.

[0035] The at least one styrene block copolymer may have a styrene content of between 10% and 50% by weight, such as between 15% and 45% by weight (e.g., between about 18% and about 44% by weight), relative to the total weight of the copolymer. The styrene content is the weight percentage of the styrene moieties (present in the polystyrene blocks) relative to the total weight of the copolymer.

[0036] In the context of the present invention, numerical ranges are to be understood as including the endpoints. For example, the range "between 10% and 50%" specifically includes the values ​​10% and 50%.

[0037] The total content of at least one styrene block copolymer in the hot-melt composition according to the invention may be between 8% and 55% by weight, preferably between 13% and 50% by weight, relative to the total weight of the composition.

[0038] According to one embodiment, in particular when the hot melt composition is used to manufacture articles comprising nonwoven fabrics, the total content of at least one styrene block copolymer is between 8% and 30% by weight, preferably between 13% and 25% by weight (e.g., about 19% by weight), relative to the total weight of the hot melt composition.

[0039] According to one embodiment, in particular when the hot-melt composition is employed in adhesive tapes or labels, the total content of the at least one styrene block copolymer is between 30% and 55% by weight, preferably between 35% and 50% by weight (for example between 40% and 45% by weight), relative to the total weight of the hot-melt composition.

[0040] Tackifying resin The hot-melt composition according to the present invention comprises at least one tackifying resin.

[0041] The at least one tackifying resin may include a resin selected from the group consisting of: - natural rosins and modified rosins, such as gum rosin, wood rosin, tall oil rosin, distilled rosin, hydrogenated rosin, dimerized rosin, polymerized rosin, - glycerol esters and pentaerythritol esters of natural and modified rosins, for example glycerol esters of light wood rosin, glycerol esters of polymerized rosin, pentaerythritol esters of light wood rosin, pentaerythritol esters of tall oil rosin, pentaerythritol esters of phenolic-modified rosin, - polyterpene resins, which are generally produced from the polymerization of terpene hydrocarbons such as the monoterpene called pinene in the presence of a Friedel-Crafts catalyst, preferably at moderately low temperatures (e.g. about 20° C. to 50° C.), - a copolymer of a terpene and a diene monomer, the diene monomer being preferably an aromatic diene monomer, such as a styrene monomer (eg styrene, methylstyrene, etc.), - phenolic-modified terpene resins, such as those resulting from the condensation of terpenes and phenols in an acidic medium, - aliphatic petroleum hydrocarbon resins (C5), resulting from the polymerization of C5-hydrocarbon monomers, - aromatic petroleum hydrocarbon resins (C9), resulting from the polymerization of C9-hydrocarbon monomers, - petroleum hydrocarbon resins (C5 / C9), resulting from the polymerization of a blend of aliphatic C5-hydrocarbon monomers and aromatic C9-hydrocarbon monomers, - dicyclopentadiene petroleum resins (DCPD), resulting from the polymerization of dicyclopentadiene monomers, optionally mixed with aromatic C9-hydrocarbon monomers and / or aliphatic C5-hydrocarbon monomers, especially aromatic C9-hydrocarbon monomers, - their corresponding hydrogenated derivatives (resulting from their subsequent full or partial hydrogenation), and - mixtures thereof.

[0042] As examples of C5-hydrocarbon monomers useful for preparing aliphatic petroleum C5-hydrocarbon resins or petroleum C5 / C9-hydrocarbon resins, mention may be made of trans-1,3-pentadiene, cis-1,3-pentadiene, 2-methyl-2-butene, cyclopentadiene, methylcyclopentadiene and / or cyclopentene.

[0043] As examples of C9-hydrocarbon monomers useful for preparing aromatic petroleum C9-hydrocarbon resins, petroleum C5 / C9-hydrocarbon resins or DCPD resins, mention may be made of vinyltoluene, indene, methylstyrene, α-methylstyrene, styrene and / or methylindene.

[0044] Preferably, the at least one tackifying resin comprises a resin selected from the group consisting of: - glycerol and pentaerythritol esters of natural and modified rosin, - copolymers of terpenes and aromatic diene monomers, -phenolic modified terpene resin, - aliphatic petroleum hydrocarbon resins (C5), resulting from the polymerization of C5-hydrocarbon monomers, - aromatic petroleum hydrocarbon resins (C9), resulting from the polymerization of C9-hydrocarbon monomers, - petroleum hydrocarbon resins (C5 / C9), resulting from the polymerization of a blend of aliphatic C5-hydrocarbon monomers and aromatic C9-hydrocarbon monomers, - dicyclopentadiene petroleum resins (DCPD), resulting from the polymerization of dicyclopentadiene monomers, optionally mixed with aromatic C9-hydrocarbon monomers and / or aliphatic C5-hydrocarbon monomers, especially aromatic C9-hydrocarbon monomers, - their corresponding hydrogenated derivatives (resulting from their subsequent full or partial hydrogenation), and - mixtures thereof.

[0045] More preferably, the at least one tackifying resin comprises a glycerol ester of natural rosin, a glycerol ester of modified rosin, a pentaerythritol ester of natural rosin, a pentaerythritol ester of modified rosin, a copolymer of terpene and aromatic diene monomer, and / or a phenolic modified terpene resin (unhydrogenated). The at least one tackifying resin may further comprise a resin selected from the group consisting of aliphatic petroleum hydrocarbon resins (C5), aromatic petroleum hydrocarbon resins (C9), dicyclopentadiene petroleum resin (DCPD), their corresponding hydrogenated derivatives (fully hydrogenated or partially hydrogenated), and mixtures thereof.

[0046] The total content of the glycerol and pentaerythritol esters of natural and modified rosin, the copolymer of terpene and aromatic diene monomer, and the phenolic-modified terpene resin in the hot-melt composition according to the present invention may be between 10% and 40% by weight, preferably between 15% and 35% by weight, more preferably between 18% and 33% by weight, relative to the total weight of the composition.

[0047] In particular, the at least one tackifying resin is a mixture of: -i) glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, copolymers of terpene and aromatic diene monomers, and / or phenolic modified terpene resins, and -ii) a resin selected from the group consisting of aliphatic petroleum hydrocarbon resins (C5), aromatic petroleum hydrocarbon resins (C9), dicyclopentadiene petroleum resin (DCPD), the corresponding hydrogenated derivatives thereof (fully hydrogenated or partially hydrogenated), and mixtures thereof.

[0048] The ii) / i) weight ratio may be between 0.5 and 2, preferably between 0.8 and 1.5.

[0049] The softening point of the tackifying resin may be at least 80° C., preferably between 80° C. and 150° C., more preferably between 90° C. and 130° C. The softening point may be measured by the ring and ball method (eg according to ASTM E28).

[0050] The acid value of the tackifying resin may be less than 20 mg KOH / gram of the resin, preferably less than 10 mg KOH / g. The acid value may be measured according to ASTM D-1639.

[0051] Unless stated otherwise, the standards referred to throughout this application are those in effect on the filing date of this application.

[0052] The weight average molecular weight of the tackifying resin may vary between 200 g / mol and 5000 g / mol, preferably between 300 g / mol and 3000 g / mol. The weight average molecular weight may be measured by size exclusion chromatography (or SEC), which is also represented by the term "gel permeation chromatography" (or GPC), preferably using polystyrene calibration.

[0053] The total content of at least one tackifying resin in the hot-melt composition according to the invention may be between 20% and 70% by weight, preferably between 30% and 65% by weight, more preferably between 35% and 60% by weight, relative to the total weight of the composition.

[0054] Acid-modified glycerides The hot-melt composition according to the invention comprises at least one acid-modified glyceride.

[0055] By "acid-modified glycerides" is meant glycerides comprising at least one carboxylic acid group (-C(O)OH), preferably between 1 and 3 carboxylic acid groups.

[0056] By "glyceride" is intended a fatty acid glyceride, ie an ester of glycerol with a fatty acid (the fatty acids being the same or different). The glyceride may be a mixture of mono-, di- and / or triglycerides of fatty acids.

[0057] By "fatty acid" is meant a molecule having an aliphatic chain which may contain one or more double bonds and which comprises a carboxylic acid group (-C(O)OH). In particular, the fatty acid comprises between 4 and 28 carbon atoms, preferably between 10 and 22 carbon atoms, more preferably between 16 and 20 carbon atoms, for example 18 carbon atoms.

[0058] The glycerides from which the acid-modified glycerides are obtained may be vegetable or animal oils (e.g. castor oil or tallow). The vegetable or animal oils may also be modified beforehand in order to obtain glycerides not found directly in nature; for example, hydroxyl groups may be introduced into the fatty acid chains (e.g. by epoxidation of double bonds, hydroformylation / hydrogenation of double bonds, etc.) and / or ether functional groups may be introduced into the fatty acid chains (e.g. by reacting the hydroxyl groups carried by the fatty acids with propylene oxide or ethylene oxide to form propoxylated glycerides or ethoxylated glycerides, respectively).

[0059] By "propoxylated glycerides" is meant glycerides comprising at least one -O-(CH2CH(CH3)O) n -H or -O-(CH(CH3)CH2O) n -H units, wherein n is an integer greater than or equal to 1.

[0060] By "ethoxylated glycerides" is meant glycerides comprising at least one -O-(CH2CH2O) n -H units, wherein n is an integer greater than or equal to 1.

[0061] In particular, the glyceride from which the acid-modified glyceride is obtained can be selected from castor oil, soybean oil, rapeseed oil, corn oil, cottonseed oil, linseed oil, olive oil, sesame oil, walnut oil, sunflower oil, safflower oil, grape oil, palm oil, tallow, coconut oil, palm kernel oil, triglycerides thereof, derivatives thereof, and mixtures thereof, the derivatives preferably being monoglycerides, diglycerides, hydroxylated monoglycerides, hydroxylated diglycerides, hydroxylated triglycerides, ethoxylated monoglycerides, ethoxylated diglycerides, ethoxylated triglycerides, propoxylated monoglycerides, propoxylated diglycerides and / or propoxylated triglycerides thereof, and the derivatives more preferably being monoglycerides, diglycerides, hydroxylated monoglycerides, hydroxylated diglycerides and / or hydroxylated triglycerides thereof.

[0062] According to a preferred embodiment, the acid-modified glyceride is obtained by reacting a glyceride containing at least one hydroxyl group (-OH) with a cyclic anhydride, advantageously at a temperature between 60° C. and 120° C., preferably between 80° C. and 110° C. When the hydroxyl group reacts with the cyclic anhydride, it opens the anhydride ring to form an ester bond and a pendant carboxylic acid group. The cyclic anhydride / glyceride molar ratio may be at least 1, preferably at least 1.0, more preferably between 1.0 and 3, for example about 1.2.

[0063] Therefore, the glyceride from which the acid-modified glyceride is obtained is preferably selected from castor oil, triglycerides of castor oil, derivatives of castor oil, derivatives of soybean oil, derivatives of rapeseed oil, derivatives of corn oil, derivatives of cottonseed oil, derivatives of linseed oil, derivatives of olive oil, derivatives of sesame oil, derivatives of walnut oil, derivatives of sunflower oil, derivatives of safflower oil, derivatives of grape oil, derivatives of palm oil, derivatives of tallow, derivatives of coconut oil, derivatives of palm kernel oil, and mixtures thereof, the derivatives being preferably their monoglycerides, diglycerides, hydroxylated monoglycerides, hydroxylated diglycerides, hydroxylated triglycerides, ethoxylated monoglycerides, ethoxylated diglycerides, ethoxylated triglycerides, propoxylated monoglycerides, propoxylated diglycerides and / or propoxylated triglycerides, the derivatives being more preferably their monoglycerides, diglycerides, hydroxylated monoglycerides, hydroxylated diglycerides and / or hydroxylated triglycerides.

[0064] By "hydroxylated" is meant that at least one hydroxyl group has been introduced into at least one fatty acid chain of the glyceride. The hydroxyl group may be attached directly or indirectly (preferably directly) to a carbon atom of the fatty acid chain. For example, when the hydroxyl group is attached indirectly, it may be introduced by hydroformylation / hydrogenation of the double bond.

[0065] More preferably, the glyceride from which the at least one acid-modified triglyceride is obtained is castor oil, a triglyceride of castor oil, and / or a hydroxylated vegetable or animal oil (preferably a vegetable oil), for example hydroxylated soybean oil, hydroxylated rapeseed oil, hydroxylated corn oil, hydroxylated cottonseed oil, hydroxylated linseed oil, hydroxylated olive oil, hydroxylated sesame oil, hydroxylated walnut oil, hydroxylated sunflower oil, hydroxylated safflower oil, hydroxylated grape oil, hydroxylated palm oil, hydroxylated tallow, in particular castor oil or a triglyceride thereof.

[0066] A vegetable or animal oil is "hydroxylated" when it has been modified to introduce at least one hydroxyl group on at least one fatty acid chain of the glyceride. The hydroxyl group may be attached directly or indirectly, preferably directly, to a carbon atom of the fatty acid chain.

[0067] By "cyclic anhydride" is meant a molecule comprising a cyclic anhydride functional group (-C(O)-OC(O)-). In particular, a cyclic anhydride has formula (I): where R 7 is a saturated or unsaturated divalent hydrocarbon radical, which may be branched, which may contain one or more rings which may be aromatic, and which may contain one or more heteroatoms selected from oxygen and sulfur (preferably oxygen).

[0068] The molar mass of the cyclic anhydride may be between 86 g / mol and 1000 g / mol, preferably between 98 g / mol and 500 g / mol.

[0069] The cyclic anhydride may be selected from maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, succinic anhydride, 2,3-dimethylsuccinic anhydride, tetrapropylene succinic anhydride (CAS: 26544-38-7, isomer with branched olefinic chain), n-dodecenyl succinic anhydride (CAS: 19780-11-1), glutaric anhydride, 2,4-dimethylglutaric anhydride, 3,3-dimethylglutaric anhydride, 3-dimethylglutaric anhydride, adipic anhydride, ethyl ... Alkylic anhydrides, cis-aconitic anhydride, 2-(2′-carboxyethyl)maleic anhydride, 1-methyl-2-(2′-carboxyethyl)maleic anhydride, octenylsuccinic anhydride, S-acetylmercaptosuccinic anhydride, nadic anhydride, methylnadic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-cyclopentanedicarboxylic anhydride, 1,2-cyclobutanedicarboxylic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, homophthalic anhydride, trimellitic anhydride, and mixtures thereof.

[0070] Advantageously, the cyclic anhydride is selected from maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, succinic anhydride, tetrapropylene succinic anhydride, n-dodecenyl succinic anhydride, glutaric anhydride, adipic anhydride, glycolic anhydride, cis-aconitic anhydride, 2-(2′-carboxyethyl)maleic anhydride, 1-methyl-2-(2′-carboxyethyl)maleic anhydride, octenylsuccinic anhydride, S-acetylmercaptosuccinic anhydride, 1,2-cyclohexanedicarboxylic anhydride, phthalic anhydride, homophthalic anhydride, trimellitic anhydride, and mixtures thereof.

[0071] Preferably, the cyclic anhydride is selected from maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, succinic anhydride, tetrapropylene succinic anhydride, n-dodecenyl succinic anhydride, glutaric anhydride, adipic anhydride, glycolic anhydride, cis-aconitic anhydride, 2-(2′-carboxyethyl)maleic anhydride, 1-methyl-2-(2′-carboxyethyl)maleic anhydride, octenyl succinic anhydride, 1,2-cyclohexanedicarboxylic anhydride, phthalic anhydride, and mixtures thereof.

[0072] More preferably, the cyclic anhydride is selected from maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, succinic anhydride, tetrapropenylsuccinic anhydride, n-dodecenylsuccinic anhydride, glutaric acid, and mixtures thereof, especially maleic anhydride.

[0073] According to a particular embodiment, the acid-modified glyceride is obtained by reacting a glyceride with a cyclic anhydride: The glyceride is selected from the group consisting of castor oil, triglycerides of castor oil, derivatives of castor oil, derivatives of soybean oil, derivatives of rapeseed oil, derivatives of corn oil, derivatives of cottonseed oil, derivatives of linseed oil, derivatives of olive oil, derivatives of sesame oil, derivatives of walnut oil, derivatives of sunflower oil, derivatives of safflower oil, derivatives of grape oil, derivatives of palm oil, derivatives of tallow, derivatives of coconut oil, derivatives of palm kernel oil, and mixtures thereof, wherein the derivatives are preferably monoglycerides, diglycerides, hydroxylated monoglycerides, hydroxylated diglycerides, hydroxylated triglycerides, ethoxylated monoglycerides, ethoxylated diglycerides, ethoxylated triglycerides, propoxylated monoglycerides, esters, propoxylated diglycerides and / or propoxylated triglycerides (more preferably monoglycerides, diglycerides, hydroxylated monoglycerides, hydroxylated diglycerides and / or hydroxylated triglycerides thereof), - the cyclic anhydride is selected from the group consisting of maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, succinic anhydride, tetrapropylene succinic anhydride, n-dodecenyl succinic anhydride, glutaric anhydride, adipic anhydride, glycolic anhydride, cis-aconitic anhydride, 2-(2′-carboxyethyl) maleic anhydride, 1-methyl-2-(2′-carboxyethyl) maleic anhydride, octenylsuccinic anhydride, S-acetylmercaptosuccinic anhydride, 1,2-cyclohexanedicarboxylic anhydride, phthalic anhydride, homophthalic anhydride, trimellitic anhydride, and mixtures thereof.

[0074] Preferably, the acid-modified glyceride is obtained by reacting a glyceride with a cyclic anhydride: the glyceride is chosen from castor oil, triglycerides of castor oil, hydroxylated soybean oil, hydroxylated rapeseed oil, hydroxylated corn oil, hydroxylated cottonseed oil, hydroxylated linseed oil, hydroxylated olive oil, hydroxylated sesame oil, hydroxylated walnut oil, hydroxylated sunflower oil, hydroxylated safflower oil, hydroxylated grape oil, hydroxylated palm oil, hydroxylated tallow, and mixtures thereof, in particular castor oil or triglycerides of castor oil, The cyclic anhydride is selected from the group consisting of maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, succinic anhydride, tetrapropenylsuccinic anhydride, n-dodecenylsuccinic anhydride, glutaric acid, and mixtures thereof, in particular maleic anhydride.

[0075] The acid value of the acid-modified glyceride may be between 20 mg KOH / gram of the glyceride and 400 mg KOH / gram of the glyceride, preferably between 40 mg KOH / g and 320 mg KOH / g. The acid value may be measured according to ASTM D-1639.

[0076] The total content of at least one acid-modified glyceride in the hot-melt composition according to the invention may be between 3% and 25% by weight, preferably between 5% and 20% by weight, relative to the total weight of the composition.

[0077] plasticizers The hot melt composition according to the present invention preferably further comprises a plasticizer.

[0078] The plasticizer may be selected from naphthenic oil, paraffin oil, olefin oligomers, polyethers of glycerol and polyethylene glycol, and mixtures thereof, and is preferably selected from naphthenic oil, paraffin oil, and mixtures thereof.

[0079] Naphthenic and paraffinic oils are petroleum-based oils consisting of a mixture of cycloalkanes (e.g., aliphatic, saturated or unsaturated C4-C7-membered hydrocarbon rings; preferably aliphatic, saturated or unsaturated C4-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, preferably aromatic C6-membered hydrocarbon rings).

[0080] The classification of naphthenic and paraffinic oils is based on the amount of each hydrocarbon in the oil. Typically, paraffinic oils have a paraffin content of at least 50% by weight relative to the total weight of the paraffinic oil, and naphthenic oils have a naphthenic content of between 30% and 40% by weight relative to the total weight of the naphthenic oil.

[0081] By "olefin oligomers" is meant polyolefins having a low weight average molecular weight, preferably between about 100 g / mol and about 10,000 g / mol. The weight average molecular weight can be measured as indicated above (by size exclusion chromatography, preferably using polystyrene calibration).

[0082] In this application, by "about X" is intended ±10% of the value of X.

[0083] As examples of olefin oligomers, mention may be made of polypropylene, polybutene, hydrogenated polyisoprene, and hydrogenated polybutadiene.

[0084] The polyether of glycerol and polyethylene glycol may be polyoxyethylene glycerol ether (CAS: 31694-55-0), polyoxypropylene glycerol ether (CAS: 25791-96-2), polyoxypropylene-polyoxyethylene glycerol ether (CAS: 9082-00-2) and / or glycerol ethoxylate-co-propoxylate triol (CAS: 51258-15-2).

[0085] The total content of plasticizers in the hot-melt composition according to the invention may be up to 20% by weight, preferably up to 15% by weight, relative to the total weight of said composition.

[0086] wax The hot melt composition according to the present invention may further comprise a wax.

[0087] The wax may be polyethylene wax, paraffin wax, Fischer-Tropsch wax and / or EVA wax, preferably polyethylene wax.

[0088] By "polyethylene wax" is meant a polyethylene homopolymer, in particular a low density polyethylene homopolymer or a high density polyethylene homopolymer, preferably a low density polyethylene homopolymer (LDPE). The number average molecular weight of the polyethylene wax is typically at most 10,000 g / mol. The number average molecular weight can be measured by size exclusion chromatography (or SEC), preferably using polystyrene calibration.

[0089] By "paraffin wax" is meant wax obtained from crude oil. It is generally composed of a complex mixture of hydrocarbons. Paraffin wax generally contains primarily straight-chain hydrocarbons and may also contain branched hydrocarbons, such as isoparaffins and other branched materials; and cycloalkanes, such as cycloparaffins and other ring-containing materials. Paraffin wax is characterized by a well-defined crystal structure.

[0090] By "Fischer-Tropsch wax" is meant a wax obtained by the so-called Fischer-Tropsch process. The Fischer-Tropsch process involves converting a synthesis gas comprising mainly hydrogen and carbon monoxide into hydrocarbons. The conversion is achieved by contacting the synthesis gas with a Fischer-Tropsch catalyst (typically an iron or cobalt-based catalyst) in a fixed bed reactor or a slurry bed reactor under low or high temperature Fischer-Tropsch operating conditions. In this way, a mixture of hydrocarbons with different boiling ranges is obtained. The Fischer-Tropsch wax is then recovered from this hydrocarbon mixture, for example by means of distillation. Fischer-Tropsch wax typically has a composition in which about 80% by volume thereof has a boiling point above 550° C. atmospheric equivalent temperature (“AET”).

[0091] By "EVA wax," it is meant an oligomeric compound prepared by a process comprising copolymerization of ethylene monomers and vinyl acetate monomers and having the following properties: (a) solid at room temperature (e.g., 23° C.); (b) a low melting point (e.g., below 100° C.); and (c) insoluble in water. The EVA copolymer of the EVA wax may be functionalized or modified in any manner possible.

[0092] The wax content may be up to 10% by weight, preferably up to 6% by weight, relative to the total weight of the hot-melt composition according to the invention.

[0093] Other additives The hot melt composition according to the present invention may further comprise one or more additives selected from ultraviolet (UV) stabilizers (or antioxidants), fillers, pigments, ultraviolet fluorescent agents or infrared fluorescent agents, and mixtures thereof, especially selected from UV stabilizers.

[0094] The total content of additives in the hot-melt composition according to the invention may be up to 20% by weight, preferably between 0.1% and 5% by weight, relative to the total weight of the composition.

[0095] Advantageously, the hot melt composition according to the present invention comprises a UV stabilizer (or antioxidant). UV stabilizers are generally introduced to protect the composition from degradation caused by reaction with oxygen (which may be formed by the action of heat or light). These compounds may include antioxidants capable of scavenging free radicals.

[0096] Examples of UV stabilizers are benzotriazoles, benzophenones, hindered amines (also called HALS, ie “hindered amine light stabilizers”); hindered phenols and polyfunctional phenols, for example phenols containing sulfur and phosphorus, preferably hindered phenols and polyfunctional phenols.

[0097] Representative hindered amines include bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate (CAS: 41556-26-7), methyl 1,2,2,6,6-pentamethyl-4-piperidinyl sebacate (CAS: 82919-37-7) and / or 4,4′-bis(α,α-dimethylbenzyl)diphenylamine.

[0098] Hindered phenols are well known to those skilled in the art and can be characterized as phenolic compounds that contain sterically bulky groups immediately adjacent to their phenolic hydroxyl groups. In particular, the tert-butyl group is typically substituted onto the benzene ring at at least one ortho position relative to the phenolic hydroxyl group. Representative hindered phenols and polyfunctional phenols include: 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, n-octadecyl 3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4,4'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-thiobis(6-tert-butyl-o-cresol), 2,6-di-tert-butylphenol, 6-(4-hydroxyphenoxy)-2,4-bis(n-octylthio)-1,3,5-triazine, 2,3,6-tris(4-hydroxy-3,5 -di-tert-butyl-phenoxy)-1,3,5-triazine, di-n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 2-(n-octylthio)ethyl 3,5-di-tert-butyl-4-hydroxybenzoate, sorbitan hexa-3(3,5-di-tert-butyl-4-hydroxy-phenyl)propionate, 2,2′-methylenebis(4-methyl-6-tert-butylphenol)phosphite, tris(p-nonylphenyl)phosphite (TNPP), bis(2,4-di-tert-butylphenyl)4,4′-diphenylene diphosphonite, tris(2,4-di-tert-butylphenyl)phosphite and / or tris(2,4-di-tert-butylphenyl)phosphate.

[0099] The UV stabilizer (or antioxidant) content may be between 0.1% and 5% by weight, preferably between 0.3% and 3% by weight, relative to the total weight of the hot-melt composition according to the invention.

[0100] The hot melt composition according to the present invention may further comprise a filler. Typical fillers include talc, calcium carbonate, clay, silica, mica, wollastonite, feldspar, aluminum silicate, aluminum oxide, hydrated aluminum oxide, glass microspheres, ceramic microspheres and / or thermoplastic microspheres.

[0101] The filler content may be up to 10% by weight, preferably up to 5% by weight, relative to the total weight of the hot-melt composition according to the invention.

[0102] The hot melt composition according to the present invention may further comprise a pigment. The pigment may be an organic pigment and / or an inorganic pigment, such as titanium dioxide.

[0103] The pigment content may be up to 5% by weight, preferably up to 3% by weight, relative to the total weight of the hot-melt composition according to the invention.

[0104] The hot melt composition according to the present invention may further comprise an ultraviolet fluorescent agent or an infrared fluorescent agent, such as 2-(6-hydroxy-3-oxo-(3H)-xanthen-9-yl)benzoic acid, disodium 6-hydroxy-3-oxo-9-xanthen-o-phthalate and / or trisodium 8-hydroxy-1,3,6-pyrenetrisulfonic acid.

[0105] The content of ultraviolet fluorescent agent or infrared fluorescent agent may be up to 3 wt%, preferably up to 1 wt%, relative to the total weight of the hot-melt composition according to the present invention.

[0106] Other features of the hot melt composition according to the invention According to one embodiment, the hot-melt composition according to the invention comprises: - 8% to 55% by weight of at least one styrene block copolymer, - 20% to 70% by weight of at least one tackifying resin, the at least one tackifying resin preferably comprising glycerol esters of natural rosin, glycerol esters of modified rosin, pentaerythritol esters of natural rosin, pentaerythritol esters of modified rosin, copolymers of terpenes and aromatic diene monomers, and / or phenolic-modified terpene resins, and optionally further comprising a resin selected from the group consisting of aliphatic petroleum hydrocarbon resins (C5), aromatic petroleum hydrocarbon resins (C9), dicyclopentadiene petroleum resins (DCPD), their corresponding hydrogenated derivatives (fully hydrogenated or partially hydrogenated), and mixtures thereof, - 3% to 25% by weight of at least one acid-modified glyceride, preferably obtained by reacting a glyceride comprising at least one hydroxyl group (-OH) with a cyclic anhydride selected from the group consisting of maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, succinic anhydride, tetrapropenylsuccinic anhydride, n-dodecenylsuccinic anhydride, glutaric anhydride, adipic anhydride, glycolic anhydride, cis-aconitic anhydride, 2-(2′-carboxyethyl)maleic anhydride, 1-methyl-2-(2′-carboxyethyl)maleic anhydride, octenylsuccinic anhydride, S-acetylmercaptosuccinic anhydride, 1,2-cyclohexanedicarboxylic anhydride, phthalic anhydride, homophthalic anhydride, trimellitic anhydride, and mixtures thereof, - up to 20% by weight of plasticizers, - optionally up to 10% by weight of waxes, and - optionally up to 20% by weight of one or more additives selected from UV stabilizers (or antioxidants), fillers, pigments, ultraviolet or infrared fluorescent agents, and mixtures thereof, Weight percentages are relative to the total weight of the composition.

[0107] Preferably, the hot melt composition according to the present invention consists essentially of the ingredients mentioned above. By "consisting essentially of" it is meant that the composition comprises, relative to the total weight of the composition, ingredients other than the ingredients mentioned above in an amount of less than 5% by weight, preferably less than 2% by weight, even more preferably less than 1% by weight.

[0108] The ingredients of this embodiment and their particular amounts are as described above (including embodiments and preferred features).

[0109] According to a particular embodiment, the hot-melt composition according to the invention comprises: - 13% to 50% by weight of at least one styrene block copolymer, preferably comprising SBBS, SBS, SEBS, SEPS, SEEPS, SIBS and / or SIS, - 35% to 60% by weight of at least one tackifying resin, preferably comprising glycerol esters of natural rosin, glycerol esters of modified rosin, pentaerythritol esters of natural rosin, pentaerythritol esters of modified rosin, copolymers of terpenes with aromatic diene monomers, and / or phenolic-modified terpene resins; and resins selected from the group consisting of aliphatic petroleum C5-hydrocarbon resins, aromatic petroleum C9-hydrocarbon resins, petroleum C5 / C9-hydrocarbon resins, DCPD petroleum resins, hydrogenated derivatives thereof, and mixtures thereof, - 5% to 20% by weight of at least one acid-modified glyceride, preferably obtained by reacting a glyceride with a cyclic anhydride: the glyceride is chosen from castor oil, triglycerides of castor oil, hydroxylated soybean oil, hydroxylated rapeseed oil, hydroxylated corn oil, hydroxylated cottonseed oil, hydroxylated linseed oil, hydroxylated olive oil, hydroxylated sesame oil, hydroxylated walnut oil, hydroxylated sunflower oil, hydroxylated safflower oil, hydroxylated grape oil, hydroxylated palm oil, hydroxylated tallow, and mixtures thereof, in particular castor oil or triglycerides of castor oil, the cyclic anhydride is selected from maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, succinic anhydride, tetrapropenylsuccinic anhydride, n-dodecenylsuccinic anhydride, glutaric acid, and mixtures thereof, in particular maleic anhydride, - up to 15% by weight of a plasticizer, preferably chosen from naphthenic oils, paraffinic oils, and mixtures thereof, - optionally up to 6% by weight of a wax, preferably a polyethylene wax, and - optionally 0.1% to 5% by weight of one or more additives chosen from UV stabilizers (or antioxidants), fillers, pigments, ultraviolet or infrared fluorescent agents, and mixtures thereof, in particular chosen from UV stabilizers, Weight percentages are relative to the total weight of the composition.

[0110] Preferably, the hot melt composition according to the present invention consists essentially of the ingredients mentioned above.

[0111] The ingredients of this embodiment and their particular amounts are as described above (including embodiments and preferred features).

[0112] Advantageously, the peel strength of the hot-melt composition according to the present invention after immersion in a hot alkaline aqueous solution is reduced compared to its peel strength before immersion. Preferably, the peel strength is reduced by at least 30%, more preferably at least 50%, after immersion in the hot alkaline aqueous solution for at least 1 minute (more preferably at least 6 minutes). The peel strength is preferably a 90° peel strength (also known as a T-peel strength) or a 180° peel strength, which can be measured on a nonwoven / polyethylene laminate specimen or on a glass plate (e.g., as described in Example 1), respectively. More preferably, the peel strength is a 90° peel strength.

[0113] By "hot alkaline aqueous solution" is intended an aqueous solution having a pH of at least 8, preferably at least 12, at a temperature between 60°C and 100°C.

[0114] According to one embodiment, the hot melt composition according to the invention is a hot melt pressure sensitive adhesive (HMPSA) composition, preferably having a pressure greater than or equal to 1 N / cm 2 The HMPSA composition typically has a G' storage modulus at 25°C of less than 1.0 MPa, particularly less than 0.1 MPa, which can be measured using a rheometer, for example, according to ASTM D4440. Loop tack can be measured as described in FINAT Test Method No. 9, for example, as described in Example 1. The HMPSA composition is particularly useful for making tapes and / or labels.

[0115] According to this embodiment, the HMPSA composition has a 180° peel strength on glass greater than or equal to 2 N / cm. The 180° peel strength can be measured as described in FINAT Test Method No. 1 published in the FINAT Technical Manual, 6th Edition (2001), for example, as described in Example 1.

[0116] The hot melt composition according to the present invention can be prepared by mixing its ingredients under heat, preferably at a temperature in the range of 140° C. to 190° C., and atmospheric pressure.

[0117] Uses of hot melt compositions The present invention also relates to the use of the hot-melt composition according to the invention as an adhesive, in particular for bonding two substrates together.

[0118] The substrates to be bonded can be of different or identical nature and have various forms.

[0119] Each substrate can be independently selected from glass (which can be coated, for example, with a metal oxide such as tin oxide, optionally further coated with a wax layer such as polyethylene wax), nonwoven fabrics, woven fabrics, absorbent fluff, super absorbent polymers (SAP), composite materials, plastics, cardboard, paper, and mixtures thereof, preferably selected from glass, nonwoven fabrics and plastics.

[0120] As examples of nonwoven fabrics, mention may be made of polyolefin (especially polyethylene and / or polypropylene) nonwoven fabrics, cotton nonwoven fabrics; polyester (especially polyethylene terephthalate and / or polybutylene terephthalate) nonwoven fabrics and / or polyamide (especially polyamide 6 and / or polyamide 66) nonwoven fabrics, preferably polyolefin nonwoven fabrics, especially polypropylene nonwoven fabrics.

[0121] Plastics (e.g. films, bottles, etc.) are based on polymers and may contain one or more additives, such as plasticizers. Examples of polymers include polyolefins (e.g. polyethylene, polypropylene and / or polybutylene), polystyrene, styrene block copolymers, natural or synthetic rubbers (e.g. polyisoprene, polybutadiene, polyprene, butadiene-isoprene copolymers, isobutylene-isoprene copolymers, polychloroprene, nitrile rubber and / or styrene-butadiene rubber), vinyl copolymers (e.g. polyvinyl chloride, which may or may not be plasticized, and / or polyvinyl acetate), olefinic copolymers (e.g. ethylene-methacrylate copolymers, ethylene-vinyl acetate copolymers, acrylonitrile-butadiene-styrene copolymers and / or ethylene-propylene copolymers), acrylic polymers and copolymers, polyurethanes, polyethers and / or polyesters (e.g. polyethylene terephthalate), preferably polyolefins, vinyl copolymers and / or polyesters, especially polyolefins.

[0122] According to a preferred embodiment, at least one of the substrates to be bonded is a plastic, in particular a plastic film, preferably made from a polyolefin (e.g. polyethylene or polypropylene). Preferably, the other substrate to be bonded is a nonwoven fabric (preferably a polyolefin nonwoven fabric) or glass, in particular glass coated with a metal oxide and optionally further coated with a wax layer. For example, the substrates to be bonded are a plastic made from polyethylene and a nonwoven fabric from polypropylene, or a plastic made from polypropylene and glass.

[0123] The present invention further relates to the use of the hot-melt composition according to the invention as an alkali-debondable adhesive.

[0124] By "alkali-debondable adhesive" is meant an adhesive which can be easily debonded from at least one substrate to which it is bonded after immersion in a hot aqueous alkaline solution. Preferably, the immersion is carried out for at least 1 min, more preferably at least 6 min.

[0125] Advantageously, the adhesive is intended to bond two substrates together, the substrates being as described above (including preferred features and embodiments). In particular, at least one of the substrates is glass (especially glass coated with a metal oxide and optionally further coated with a wax layer) or a nonwoven fabric (especially a polypropylene nonwoven fabric).

[0126] According to a first embodiment, the hot-melt composition according to the invention is HMPSA for use as an alkali-debondable adhesive. Preferably, the adhesive can be debonded by at least 70%, more preferably by at least 80%, from at least one substrate, in particular glass (especially glass coated with a metal oxide and optionally further coated with a wax layer), after immersion in a hot aqueous alkaline solution. The debonding percentage can be determined visually.

[0127] According to a second embodiment, the hot melt composition according to the invention is not HMPSA and is used as an alkali-debondable adhesive. Preferably, the peel strength of the adhesive after immersion in a hot alkaline aqueous solution is reduced by at least 30%, more preferably by at least 50%, compared to its peel strength before immersion. The peel strength is preferably a 90° peel strength, which can be measured as described in Example 1. Preferably, at least one of the substrates from which the adhesive is debonded is a nonwoven fabric (in particular a polypropylene nonwoven fabric).

[0128] Method for bonding substrates Furthermore, the present invention relates to a method for bonding substrates, comprising: - heating the hot melt composition according to the invention, for example at a temperature between 140° C. and 190° C., for at least a period of time long enough to render the composition liquid enough to be applied to a substrate (for example at least two hours), and then - coating the composition on the surface of a first substrate, and then - contacting the coated surface of the first substrate with the surface of the second substrate so as to form a bonded joint bonding the two substrates.

[0129] The hot melt composition may or may not be HMPSA.

[0130] Preferably, the bonded substrates form an assembled product (or laminate) or a labeled article.

[0131] The substrates used in the method may be different or of the same nature and may take various forms.

[0132] Each substrate can be independently selected from glass (which can be coated, for example, with a metal oxide such as tin oxide, optionally further coated with a wax layer such as polyethylene wax), nonwoven fabrics, woven fabrics, absorbent fluff, super absorbent polymers (SAP), composite materials, plastics, cardboard, paper, and mixtures thereof, preferably selected from glass, nonwoven fabrics and plastics.

[0133] Advantageously, the nonwoven fabric is as described above for the use of the hot-melt composition according to the invention, in particular a polyolefin nonwoven fabric.

[0134] Advantageously, the plastic is based on a polymer, in particular a polyolefin, as described above for the use of the hot-melt composition according to the invention.

[0135] According to a preferred embodiment, at least one of the substrates is a plastic, in particular a plastic film, preferably made from a polyolefin (e.g. polyethylene or polypropylene). Preferably, the other substrate is a nonwoven fabric (preferably a polyolefin nonwoven fabric) or glass, in particular glass coated with a metal oxide and optionally further coated with a wax layer. For example, the substrates are a plastic made from polyethylene and a nonwoven fabric from polypropylene, or a plastic made from polypropylene and glass.

[0136] The hot melt composition according to the present invention can be coated or applied by various application techniques known in the art, including contact application (such as slot die coating) and non-contact application (such as spraying, fiberizing or curtain coating), preferably contact application.

[0137] The amount of hot melt composition applied per surface unit can vary within a very wide range, for example between 0.1 g / m 2 and 50g / m 2 It depends on the substrate used.

[0138] Preferably, the method for bonding substrates according to the present invention further includes a cooling step, preferably performed at room temperature (e.g., 18-25°C), to solidify the hot melt composition. When the hot melt composition is not HMPSA, the cooling step is generally performed after the contacting step. When the hot melt composition is HMPSA, the cooling step may be performed after the coating step or after the contacting step, and may be performed before coating the surface of the first substrate to be bonded; in the latter case, the HMPSA may be first applied to the non-adhesive layer in a molten state, then cooled and transferred (e.g., by lamination) to the surface of the first substrate to be bonded (transfer coating).

[0139] Products The present invention further relates to an article comprising the hot-melt composition according to the invention.

[0140] According to a preferred embodiment, the composition bonds at least two substrates of the article according to the invention. The at least two substrates can be adhesively connected by a layer of the hot melt composition according to the invention sandwiched between the two substrates and / or by points of the hot melt composition according to the invention.

[0141] The article is obtained attributable to the process for bonding substrates according to the invention.

[0142] The substrate is preferably as described above (including embodiments and preferred features) for the method for bonding a substrate according to the present invention.

[0143] According to one embodiment, the article is an assembled product, such as a disposable diaper, disposable training pants, feminine sanitary napkin or panty liner, disposable adult incontinence pad or panty liner, absorbent pad, surgical drape, surgical mask, toilet paper, tissue or wipe. Preferably, at least one of the substrates being bonded is a nonwoven fabric, which can be bonded to a plastic; the nonwoven fabric and the plastic are preferably as described above (including embodiments and preferred features) for the method for bonding substrates according to the present invention.

[0144] According to one embodiment, the article is a labeled item, in particular a labeled package, bag or container (e.g., a bottle), preferably a labeled container, such as a labeled bottle. Preferably, at least one of the substrates is a plastic bonded to plastic or glass (preferably glass); the plastic and glass are preferably as described above (including embodiments and preferred features) for the method for bonding substrates according to the present invention.

[0145] Multilayer systems and self-adhesive products The present invention also relates to a multilayer system comprising a hot-melt composition according to the invention, said composition being HMPSA.

[0146] In particular, the multilayer system according to the invention comprises: - an adhesive layer consisting of a hot-melt composition according to the invention, said composition being HMPSA, - a support layer adjacent to the adhesive layer, and - A protective layer or coating adjacent to the adhesive layer.

[0147] The support layer is preferably prepared from a paper layer or a plastic layer. The plastic layer is based on one or more polymers and may contain one or more additives, such as plasticizers. Examples of suitable polymers for the plastic layer include polyolefins (e.g., polyethylene, polypropylene, and / or polybutylene), polystyrene, natural or synthetic rubbers (e.g., polyisoprene, polybutadiene, polyprene, butadiene-isoprene copolymer, isobutylene-isoprene copolymer, polychloroprene, nitrile rubber, and / or styrene-butadiene rubber), vinyl copolymers (e.g., polyvinyl chloride, which may or may not be plasticized; and / or polyvinyl acetate), olefinic copolymers (e.g., ethylene-methacrylate copolymers, ethylene-vinyl acetate copolymers, acrylonitrile-butadiene-styrene copolymers, and / or ethylene-propylene copolymers), acrylic polymers and copolymers, polyurethanes, polyethers, and / or polyesters (e.g., polyethylene terephthalate), preferably polyolefins, vinyl copolymers, and / or polyesters, especially polyolefins.

[0148] Other layers (particularly plastic layers) may be bonded to the support layer. In particular, a plastic film may be used, comprising a support layer (being a plastic layer) and at least one plastic layer different from the support layer. For example, the support layer may be a polyolefin (e.g., polypropylene) plastic layer bonded to a polyester (e.g., polyethylene terephthalate) plastic layer.

[0149] The support layer is preferably a printable support layer.

[0150] Since the protective layer is a non-adhesive layer, the protective layer can be easily removed without changing the adhesive layer that remains adhered to the support layer.

[0151] Preferably, the protective layer or coating comprises a silicone-based material. The coating can be applied to the surface of the support layer that is not in contact with the adhesive layer (or a layer bonded to the support layer) or to the surface of another layer (which is not the support layer or a layer bonded to the support layer) (e.g., a paper layer).

[0152] According to a preferred embodiment, the multilayer system according to the invention is packaged in the form of a winding (or coil) wound around a reel, the dimensions of which can vary within a wide range. Thus, the diameter of such a coil can range from 0.25 m to 1 m and its width from 0.25 m to 2 m.

[0153] According to this preferred embodiment, the surface of the support layer opposite to the contact surface of the adhesive layer or the surface of the layer to which the support layer is bonded is advantageously coated with a silicone-based material (which forms a protective coating). Such multilayer systems are sometimes referred to as "linerless." For converters who convert these web stocks into finished self-adhesive products (such as labels or tapes), the packaging is particularly advantageous due to its simplicity and the resulting economies.

[0154] For example, self-adhesive labels can be obtained by a conversion process of a multilayer system comprising: - an optional step of printing onto a printable support layer of a multilayer system, and then - a step of die-cutting the multilayer system (excluding the protective layer) into the shape and size of the self-adhesive label designed for its final use, and then - a step of removing the undesirable parts of the multilayer system that have been cut, namely the adhesive layer, the support layer and, if present, the layer bonded to the support layer ("peeling" step). Thus, after this latter step, the self-adhesive label can be easily removed from the protective layer.

[0155] The multilayer system according to the invention can be produced by: adding a quantity typically between 10 g / m 2 and 50g / m 2 The hot melt composition according to the present invention (HMPSA) is applied in a molten state to a support layer or protective layer at a temperature between 140°C and 190°C to form the adhesive layer. This application can be carried out by known coating techniques such as lip nozzle coating or curtain coating. The HMPSA is usually applied to the protective layer via a lip nozzle, and the assembly is then laminated to the support layer (transfer coating). Depending on the application temperature, the HMPSA can be applied directly to the support layer by curtain coating.

[0156] The present invention also relates to self-adhesive products obtainable from the multilayer system according to the invention, such as labels and tapes (preferably labels).

[0157] The self-adhesive product according to the invention can be obtained by converting the multilayer system according to the invention. In this case, the support layer is preferably printable. For example, the self-adhesive label can be obtained by the conversion method of the multilayer system as described above.

[0158] The converted multilayer system can be used in a production line of items to be labeled by means of an automated system which separates the self-adhesive label from the protective layer and adheres it to the item to be labeled. The labeled item is preferably as described above.

[0159] Uses of acid-modified glycerides The present invention also relates to the use of an acid-modified glyceride for reducing the adhesiveness of a hot melt composition when the composition is immersed in a hot alkaline aqueous solution. Preferably, the immersion is carried out for at least 1 minute, more preferably at least 6 minutes.

[0160] The acid-modified glycerides are as described above (including preferred features and embodiments).

[0161] The hot melt composition preferably comprises a styrene block copolymer as described above (including preferred features and embodiments). The hot melt composition may further comprise a tackifying resin, a plasticizer and / or other additives as described above (including preferred features and embodiments).

[0162] The reduction in adhesion can result in a reduction in the peel strength (preferably 90° peel strength) of the hot melt composition after immersion in a hot alkaline aqueous solution. Preferably, the peel strength of the hot melt composition after immersion in the hot alkaline aqueous solution is reduced by at least 30%, more preferably at least 50%. The peel strength is measured as described in Example 1. Preferably, at least one of the substrates from which the composition is debonded is a nonwoven fabric as described above (particularly a polypropylene nonwoven fabric).

[0163] The reduction in adhesion can result in at least 70% debonding, more preferably at least 80% debonding, of the hot melt composition from at least one substrate, particularly glass (particularly glass coated with a metal oxide and optionally further coated with a wax layer), after immersion in a hot alkaline aqueous solution. The percentage of debonding can be determined visually.

[0164] Methods used for recycling Finally, the present invention relates to a method for recovering an article comprising a hot-melt composition according to the present invention, said composition bonding at least two substrates of said article. The method comprises a step of immersing the article in a hot alkaline aqueous solution and a step of debonding the substrates bonded by the hot-melt composition. The debonding step can be performed while the article is in the hot alkaline aqueous solution and / or after it has been removed from the hot alkaline aqueous solution.

[0165] Preferably, the impregnation step is carried out for at least 1 min, more preferably at least 6 min.

[0166] Advantageously, the article is as described above (including preferred features and embodiments). In particular, the article is an assembled product or a labelled item.

[0167] According to one embodiment, the article is an assembled product. When implementing the method according to the invention, the substrates (bonded by the hot-melt composition) can be debonded, and at least one of these substrates can be recycled, in particular to produce a new assembled product. In particular, the recyclable substrate is a nonwoven fabric (in particular a polypropylene nonwoven fabric).

[0168] According to one embodiment, the article is a labeled item. When implementing the method according to the invention, the label can be detached from the item to which it is adhered, and the item (lacking its label) can be recycled, in particular reused. In particular, the recyclable item is plastic or glass, preferably glass (which can be coated, for example, with a metal oxide such as tin oxide, optionally further coated with a wax layer such as polyethylene wax).

[0169] Advantageously, the debonding step results in complete separation of the hot melt composition from the article without leaving any residue of the composition on the surface of the article, and the hot alkaline aqueous solution is not contaminated by the composition, in particular the composition remaining on the label. In the case of industrial implementation of the method, the result is less contamination of the wash water and a more economical recycling process, especially from the perspective of water consumption.

[0170] All embodiments described above can be combined with one another. In particular, the various aforementioned ingredients (and particularly preferred embodiments) in the hot melt composition can be combined with one another.

[0171] The following examples illustrate the present invention without limiting it. Example Example 1: Materials and methods Material The following materials are used: -Kraton by Kraton TM D1124 PT: a mixture of a branched styrene-isoprene-styrene triblock copolymer and a styrene-isoprene diblock copolymer having a styrene content of about 30% by weight, relative to the total weight of the mixture, and a diblock content of about 30% by weight, relative to the total weight of the mixture; -Kraton by Kraton TM D1165 PT: a mixture of a linear styrene-isoprene-styrene triblock copolymer and a styrene-isoprene diblock copolymer having a styrene content of about 30% by weight, relative to the total weight of the mixture, and a diblock content of about 20% by weight, relative to the total weight of the mixture; -TSRC CORPORATION 4411A: a linear styrene-isoprene-styrene block copolymer having a styrene content of about 44% by weight relative to the total weight of the copolymer; -TSRC CORPORATION 4186A: a mixture of a star-shaped styrene-isoprene-styrene triblock copolymer and a styrene-isoprene diblock copolymer having a styrene content of about 18% by weight, relative to the total weight of the mixture, and a diblock content of about 73% by weight, relative to the total weight of the mixture; -Kraton by Kraton TM G1726 VS: a mixture of a linear styrene-ethylene / butylene-styrene triblock copolymer and a styrene-ethylene / butylene diblock copolymer having a styrene content of about 30% by weight, relative to the total weight of the mixture, and a diblock content of about 70% by weight, relative to the total weight of the mixture; -Versalis Sol T 166: a mixture of a linear styrene-butadiene-styrene triblock copolymer and a styrene-butadiene diblock copolymer having a styrene content of about 30% by weight, relative to the total weight of the mixture, and a diblock content of about 10% by weight, relative to the total weight of the mixture; -Sylvares by Kraton TM ZT 105LT: styrenated terpene resin (tackifying resin) with a softening point between 102°C and 108°C; -Escorez by ExxonMobil Chemical TM 5600: Hydrogenated aromatic modified dicyclopentadiene resin (tackifying resin) having a softening point of about 102°C and a number average molecular weight of about 500 g / mol; -Escorez by ExxonMobil Chemical TM 5400: fully hydrogenated dicyclopentadiene resin (tackifying resin) having a softening point of about 103°C and a number average molecular weight of about 400 g / mol; -Escorez by ExxonMobil Chemical TM 5615: Hydrogenated aromatic modified dicyclopentadiene resin (tackifying resin) having a softening point of about 118°C and a number average molecular weight of about 570 g / mol; -Kraton's Sylvalite TM RE 100S: pentaerythritol ester of tall oil rosin (CAS: 8050-26-8) with a softening point between 97°C and 102°C and an acid value of about 5 mgKOH / g ester (tackifying resin); -Honeywell 617: Low density polyethylene (LDPE) homopolymer (wax) with a density of 0.91; - Maleic acid-modified castor oil from BOCSciences, BOCSCI[nc.: castor oil triglyceride monomaleate (CAS: 241153-84-4); - castor oil from Haihang Industry Co., Ltd.: ricinoleic acid triglyceride (CAS: 8001-79-4) with a molar mass equal to 933 g / mol; - Maleic anhydride from Sigma-Aldrich: CAS: 108-31-6, molar mass equal to 98.06 g / mol; -BASF 1010: Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS: 6683-19-8) (antioxidant); -BASF 168: Tris(2,4-di-tert-butylphenyl)phosphite (CAS: 31570-04-4) (antioxidant); -TSRC CORPORATION 3206: A mixture of a linear styrene-butadiene-styrene triblock copolymer and a styrene-butadiene diblock copolymer having a styrene content of about 29% by weight, relative to the total weight of the mixture, and a diblock content of about 18% by weight, relative to the total weight of the mixture; -KOLONINDUSTRIES SU-210: a hydrogenated C5 aliphatic hydrocarbon resin (CAS: 69430-35-9) having a softening point of about 110° C., an acid value of less than 1 mgKOH / gram of resin, and a weight average molecular weight of about 620 g / mol (tackifying resin); Idemitsu's I-MARVS-100: partially hydrogenated C5 / C9 hydrocarbon resin (CAS: 69430-35-9) having a softening point of about 100° C. and a weight-average molecular weight of about 700 g / mol (tackifying resin); - NYFLEX 223 from NINAS: naphthenic oil (CAS: 64742-52-5) (plasticizer).

[0172] Preparation of acid-modified castor oil Castor oil and maleic anhydride were stirred in a round bottom flask at 100°C under nitrogen atmosphere for approximately 2-3 hours.

[0173] The amount of castor oil and maleic anhydride depends on the target molar ratio of maleic anhydride / castor oil. For example, for a target molar ratio equal to 1.0, 180 g of castor oil and 19 g of maleic anhydride can be used.

[0174] Depending on the concentration of maleic anhydride (e.g. for a maleic anhydride / castor oil molar ratio greater than 1), it may be necessary to purify (i.e., wash) the oil with water until the anhydride bands (1849 cm-1 and 1779 cm-1) are completely separated. 1 ) is no longer detected by infrared spectroscopy to eliminate the residues of excess maleic anhydride.

[0175] In Tables 1 and 3, "Modified Castor Oil X" refers to castor oil modified with maleic anhydride, the maleic anhydride / castor oil molar ratio for this preparation being equal to X.

[0176] 180° peeling on glass The adhesion of the composition to be evaluated was determined by a 180° peel test on a glass plate as described in FINAT Test Method No. 1 published in the FINAT Technical Manual, 6th edition (2001). FINAT is the International Federation for Self-adhesive Label Manufacturers and Converters. The principle of the test is as follows. Using a 20 g / m 2 A 19 μm thick PET film laminated to a 50 μm thick OPP film with a molten amount of the composition to be evaluated was pre-coated on the OPP side of a support layer consisting of a 19 μm thick PET film laminated to a 50 μm thick OPP film with a two-component polyurethane adhesive. A test specimen in the form of a rectangular strip (measuring 25 mm x 175 mm) was cut from the self-adhesive support thus obtained. This test specimen was fastened to a substrate consisting of a glass plate. The resulting assembly was left at room temperature for 20 minutes and then introduced into a tensile testing machine capable of peeling or debonding the strip at an angle of 180° and at a separation rate of 300 mm / min. This machine measures the force required to debond the strip under these conditions. The results are expressed in N / cm.

[0177] Ring quick adhesive The tack of the compositions to be evaluated was determined by the loop quick tack test described in FINAT Test Method No. 9. 2 A 50 μm thick OPP film is pre-coated with a quantity of the composition (in the molten state) so as to obtain a rectangular strip measuring 25 mm x 175 mm. The two ends of this strip are joined together to form a loop, with the adhesive layer facing outward. The joined ends are placed in the movable jaws of a tensile testing machine capable of applying a displacement rate of 300 mm / min along the vertical axis, making it possible to move back and forth. The lower part of the loop, placed in a vertical position, is first brought into contact with a horizontal glass plate measuring 25 mm x 30 mm, above a square area measuring approximately 25 mm per side. Once this contact occurs, the direction of displacement of the jaws is reversed. The tackiness is the maximum force required to completely detach the ring from the glass plate.

[0178] PE debonding and SnO debonding for label applications The thermal debondability of labels coated with the composition to be evaluated, previously fastened to a glass substrate, in an alkaline aqueous medium was determined by the following test.

[0179] Glass bottles with a diameter of 5 cm and a height of approximately 20 cm were used and divided into two groups based on the properties of the constituent glass. In practice, the glass has two types of surface layers, depending on the coating treatment applied during bottle manufacture. The first type of layer essentially consists of tin oxide. The second type essentially consists of an oxidized polyethylene wax emulsion applied to the tin oxide layer. The second type of layer is characteristic of new glass bottles. The first type is characteristic of glass bottles that have been immersed in an alkaline aqueous solution during at least one cleaning cycle. Below, the first group of bottles is designated "SnO," and the second group of bottles is designated "PE."

[0180] The composition to be tested is applied to the same support layer as described above for the 180° peel test and under the same coating conditions. Rectangular labels (7 cm×5 cm) are cut from the self-adhesive support thus obtained and fastened to the glass bottle by simple pressing, and the assembly is left at room temperature for 24 hours.

[0181] Next, the labeled glass bottles were immersed in a pH 12 aqueous solution heated to 80° C. in a thermostat. After the bottles were immersed for 60 seconds, the percentage of label debonding (hereinafter referred to as “% debonding”) for the “SnO” type bottles and the “PE” type bottles was visually determined.

[0182] T-Peel for nonwoven applications To measure the T-peel strength, a laminated specimen was formed by using a May coater at 100 m / min. Specifically, the composition to be tested was first heated at 177°C and then compressed at 2 g / m by slit coating with different open times of typically 0.05-0.5 s and a nip roller of 10 kPa-4 mPa. 2 or 5g / m 2 Applied to nonwoven fabrics (15g / m 2 Hydrophilic spunbond nonwoven polypropylene (Fibertex). The nonwoven fabric coated with the composition and a polyethylene film (22 μm, Trioplanex) were superimposed on each other via the composition to obtain a laminate (NW / PE). The laminate was then stored at 25°C for 24 hours under an atmosphere of 50% RH (relative humidity) to cool and solidify the composition. The laminate was then cut to obtain test specimens having a width of 25 mm and a length of 152 mm.

[0183] Shortly after cooling and solidifying (at 25° C. and 50% RH) for 24 hours, the initial T-peel strength was measured on the laminated specimens obtained as described above. The T-peel test was performed using a peel force tester (Instron) by pulling the specimens apart at a rate of 305 mm / min at 23° C. and 50% RH.

[0184] The T-peel strength after alkaline solution was measured as the initial T-peel strength, except that the specimen was immersed in a 1 wt % NaOH aqueous solution heated to 60° C. in a thermostat for 6 min before performing the T-peel test.

[0185] Example 2: Preparation and properties of the composition according to the invention for label applications Compositions 1-8 were prepared by mixing the ingredients shown in Table 1 below (percentages are weight percentages relative to the total weight of the composition) at 180° C. and atmospheric pressure until a homogeneous mixture was obtained. Table 1: Ingredients of Compositions 1-8

[0186] Their properties were then evaluated as described in Example 1 (see 180° peel on glass, loop quick bond, PE debonding for label applications, and SnO debonding), and the results are shown in Table 2. Composition 1(Invention) 2(Invention) 3(Invention) 4(Invention) 5(Invention) 6 (Invention) 7 (Invention) 8 (Invention) 180° peel strength on glass (N / cm) 6 8 5 2 2 4 5 2 <![CDATA[Circular quick adhesion (N / cm 2 )]]> 5 1 2 4 1 4 3 2 PE% debonding 100 90 80 100 80 80 100 100 SnO% debonding 100 100 100 100 100 100 100 100 Table 2: Properties of compositions 1-8

[0187] When bonded to glass sheets, the 180° peel strength of the adhesives intended for the production of self-adhesive labels is generally greater than or equal to 2 N / cm, preferably greater than or equal to 4 N / cm. Therefore, all compositions 1 to 8 according to the invention are suitable for the production of self-adhesive labels intended for glass.

[0188] In addition, the tack of PSA is usually equal to or greater than 1 N / cm 2 Thus, compositions 1 to 8 according to the present invention are sufficiently tacky to be used as PSAs.

[0189] Furthermore, compositions 1 to 8 according to the invention make it possible to obtain labels which, after immersion in an alkaline aqueous solution, can be debonded to an extent of at least 80% from glass bottles having an external surface layer substantially comprising an oxidized polyethylene wax emulsion applied to a tin oxide layer.

[0190] Finally, compositions 1 to 8 according to the invention make it possible to obtain labels completely removable from glass bottles having an external surface layer substantially comprising tin oxide after immersion in an alkaline aqueous solution.

[0191] Example 3: Preparation and properties of the composition according to the invention for nonwoven applications Compositions 9 and 10 were prepared by mixing the ingredients shown in Table 3 below (percentages are weight percentages relative to the total weight of the composition) at 180° C. and atmospheric pressure until a homogeneous mixture was obtained to form a hot melt adhesive that was not HMPSA. Table 3: Ingredients of Composition 9 and Composition 10

[0192] Their properties were then evaluated as described in Example 1 (see T-peel for nonwoven applications) and the results are shown in Table 4. Composition 9 10 <![CDATA[Initial T-peel 2 g / m 2 (N / 25 mm)]]> 0.47 0.57 <![CDATA[T-peel 2 g / m after alkaline solution 2 (N / 25 mm)]]> 0.1 0.2 <![CDATA[Initial T-peel 5 g / m 2 (N / 25 mm)]]> 1.29 2.18 <![CDATA[T-peel after alkaline solution 5 g / m 2 (N / 25 mm)]]> 0.57 0.24 Table 4: Properties of Compositions 9 and 10

[0193] Compositions 9 and 10 according to the invention make it possible to significantly reduce the T-peel strength after immersion in an alkaline solution.

[0194] Thus, when a nonwoven substrate needs to be debonded after use (e.g. for recycling), compositions 9 and 10 according to the invention can be employed, as they make it easier to debond the substrate after immersion in an alkaline solution.

Claims

1. A hot melt composition comprising: - at least one styrene block copolymer, - at least one tackifying resin, and - at least one acid-modified glyceride, which is a glyceride comprising at least one carboxylic acid group.

2. The hot melt composition of claim 1, wherein the at least one styrenic block copolymer comprises SBBS, SBS, SEBS, SEPS, SEEPS, SIBS and / or SIS.

3. The hot melt composition according to claim 1 or 2, wherein the tackifying resin has a softening point of at least 80°C.

4. The hot melt composition according to any one of claims 1 to 3, wherein the at least one tackifying resin comprises a glycerol ester of natural rosin, a glycerol ester of modified rosin, a pentaerythritol ester of natural rosin, a pentaerythritol ester of modified rosin, a copolymer of terpene and aromatic diene monomer, and / or a phenolic modified terpene resin, and optionally further comprises a resin selected from the group consisting of aliphatic petroleum hydrocarbon resins (C5), aromatic petroleum hydrocarbon resins (C9), dicyclopentadiene petroleum resin (DCPD), their corresponding hydrogenated derivatives (fully hydrogenated or partially hydrogenated), and mixtures thereof.

5. The hot melt composition according to any one of claims 1 to 4, wherein the acid-modified glyceride is obtained by reacting a glyceride containing at least one hydroxyl group (-OH) with a cyclic anhydride.

6. The hot melt composition according to claim 5, wherein the glyceride from which the acid-modified glyceride is obtained is selected from castor oil, triglycerides of castor oil, derivatives of castor oil, derivatives of soybean oil, derivatives of rapeseed oil, derivatives of corn oil, derivatives of cottonseed oil, derivatives of linseed oil, derivatives of olive oil, derivatives of sesame oil, derivatives of walnut oil, derivatives of sunflower oil, derivatives of safflower oil, derivatives of grape oil, derivatives of palm oil, derivatives of tallow, derivatives of coconut oil, derivatives of palm kernel oil, and mixtures thereof.

7. The hot melt composition according to claim 5 or 6, wherein the cyclic anhydride is selected from maleic anhydride, itaconic anhydride, citraconic anhydride, dimethylmaleic anhydride, succinic anhydride, 2,3-dimethylsuccinic anhydride, tetrapropylene succinic anhydride, n-dodecenyl succinic anhydride, glutaric anhydride, 2,4-dimethylglutaric anhydride, 3,3-dimethylglutaric anhydride, 3-dimethylglutaric anhydride, adipic anhydride, glycolic anhydride, cis-aconitic anhydride, 2-(2′-carboxyethyl)maleic anhydride, 1-methyl-2-(2′-carboxyethyl)maleic anhydride, octenylsuccinic anhydride, S-acetylmercaptosuccinic anhydride, nadic anhydride, methylnadic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-cyclopentanedicarboxylic anhydride, 1,2-cyclobutanedicarboxylic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, homophthalic anhydride, trimellitic anhydride, and mixtures thereof.

8. The hot-melt composition according to any one of claims 1 to 7, wherein the total content of the at least one acid-modified glyceride is between 3% and 25% by weight relative to the total weight of the composition.

9. Use of the hot melt composition according to any one of claims 1 to 8 as an adhesive.

10. Use of the hot-melt composition according to any one of claims 1 to 8 as an alkali-debondable adhesive.

11. A method for bonding substrates, comprising: - heating the hot melt composition according to any one of claims 1 to 8 for at least a sufficient period of time to render the composition sufficiently liquid to be applied to a substrate, and then - coating the composition on the surface of a first substrate, and then - contacting the coated surface of the first substrate with the surface of a second substrate so as to form a bonded joint bonding the two substrates.

12. An article comprising the hot melt composition according to any one of claims 1 to 8.

13. A multi-layer system comprising the hot melt composition according to any one of claims 1 to 8, which is a hot melt pressure sensitive adhesive composition.

14. Self-adhesive product obtainable from the multilayer system according to claim 13.

15. Use of an acid-modified glyceride for reducing the adhesion of a hot melt composition when the composition is immersed in a hot alkaline aqueous solution.

16. A method for recycling an article comprising the hot-melt composition according to any one of claims 1 to 8, wherein the composition bonds at least two substrates of the article, the method comprising the steps of immersing the article in a hot alkaline aqueous solution and debonding the substrates bonded by the hot-melt composition.

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