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EP-4735525-A1 - HOT MELT ADHESIVE

EP4735525A1EP 4735525 A1EP4735525 A1EP 4735525A1EP-4735525-A1

Abstract

The present invention concerns a hot melt adhesive composition comprising: – a) a styrene block polymeric component; – b) at least one tackifying resin; – c) a biobased plasticizer having a weight average molecular weight higher than or equal to 2 000 g/mol, wherein the hot melt adhesive composition comprises a styrene content higher than or equal to 8.0%, and wherein the total weight content of the biobased plasticizer c) is lower than or equal to 12% by weight based on the weight of the hot melt adhesive composition.

Inventors

  • CESCHINI, Barbara
  • SEBA, Bouchra

Assignees

  • Bostik SA

Dates

Publication Date
20260506
Application Date
20240624

Claims (20)

  1. 1. A hot melt adhesive composition comprising: - a) a styrene block polymeric component; - b) at least one tackifying resin; - c) a biobased plasticizer having a weight average molecular weight higher than or equal to 2 000 g/mol, wherein the hot melt adhesive composition comprises a styrene content higher than or equal to 8.0%, and wherein the total weight content of the biobased plasticizer c) is lower than or equal to 12% by weight based on the weight of the hot melt adhesive composition.
  2. 2. The hot melt adhesive composition according to claim 1 , wherein the styrene block polymeric component comprises a styrene block copolymer selected from the group consisting of SB, SI, SEB, SEP, SBBS, SBS, SEBS, SEPS, SEEPS, SIBS, SIS, random-block SBR, random-block SIR, and mixtures thereof.
  3. 3. The hot melt adhesive composition according to anyone of claim 1 or 2, wherein the styrene block polymeric component comprises a SIS or a SBS copolymer.
  4. 4. The hot melt adhesive composition according to anyone of claims 1 to 3, wherein it comprises from 5 % to 35 % by weight, preferably from 10% to 30% by weight, and even more preferably from 10% to 30% by weight of styrene block polymeric component, based on the total weight of the hot melt adhesive composition.
  5. 5. The hot melt adhesive composition according to anyone of claims 1 to 4, wherein the at least one tackifiying resin is selected from the group consisting of: i) natural and modified rosins and the hydrogenated derivatives thereof, such as, for example, gum rosins, wood rosins, tail-oil rosins, distilled rosins, dimerized rosins and polymerized rosins; ii) glycol, glycerol and pentaerythritol esters of natural and modified rosins, and the hydrogenated derivatives thereof, iii) polyterpene homopolymers and the hydrogenated derivatives thereof; iv) copolymers of terpene with a diene monomer, and the hydrogenated derivatives thereof; v) phenolic-modified terpene resins; and mixtures thereof.
  6. 6. The hot melt adhesive composition according to claim 5, wherein it comprises a mixture of at least one tackifying resin ii) and at least one tackifying resin iii).
  7. 7. The hot melt adhesive composition according to anyone of claims 1 to 6, wherein it comprises from 50% to 90 %, preferably from 55% to 80 %, and more preferably from 55% to 70% by weight of a tackifying resin (or of the mixture of tackifying resins in case a plurality of tackifying resins are present in the hot melt adhesive composition), based on the total weight of the hot melt adhesive composition.
  8. 8. The hot melt adhesive composition according to anyone of claims 1 to 7, wherein the styrene content of the hot melt adhesive composition ranges from 8.0% to 15.0%, more preferably from 9.0% to 12.0%.
  9. 9. The hot melt adhesive composition according to anyone of claims 1 to 8, wherein the biobased plasticizer has a weight average molecular weight ranging from 3 000 g/mol to 12 000 g/mol, more preferably ranging from 3 000 g/mol to 6 000 g/mol.
  10. 10. The hot melt adhesive composition according to anyone of claims 1 to 9, wherein the biobased plasticizer is selected from animal fat, plant oil (e.g. canola oil, corn oil, soybean oil, epoxidized soybean oil, palm oil, peanut oil, olive oil, sunflower oil, rapeseed oil, jatropha oil, coconut oil, castor oil, etc.), lactic acid derivatives, modified versions thereof, fatty acid derivatives, and combinations thereof.
  11. 11 . The hot melt adhesive composition according to anyone of claims 1 to 10, wherein the biobased plasticizer has an acid number ranging from 1 to 20, preferably from 3 to 20 mg KOH/g.
  12. 12. The hot melt adhesive composition according to anyone of claims 1 to 11 , wherein the biobased plasticizer has a viscosity at 25°C ranging from 1000 to 5000 mPas, preferably from 1 500 to 2 500 mPas.
  13. 13. The hot melt adhesive composition according to anyone of claims 1 to 12, wherein the biobased plasticizer is a fatty acid derivative, preferably a fatty acid ester, more preferably a fatty acid polyester, and even more preferably a homopolymer of ricinoleic acid.
  14. 14. The hot melt adhesive composition according to anyone of claims 1 to 13, wherein it comprises from 1 % to 10% by weight, preferably from 2% to 10% by weight of the biobased plasticizer c) based on the total weight of the hot melt adhesive composition.
  15. 15. The hot melt adhesive composition according to anyone of claims 1 to 14, wherein it comprises at least one fatty acid derivative d) having a weight average molecular weight lower than or equal to 1 500 g/mol, preferably lower than or equal to 1 000 g/mol, and even more preferably ranges from 250 g/mol to 1 000 g/mol.
  16. 16. The hot melt adhesive composition according to anyone of claims 1 to 15, wherein it has a Brookfield viscosity at 163°C of from about 2000 to about 10000 mPa.s, preferably from about 3000 to about 9000 mPas.
  17. 17. The hot melt adhesive composition according to anyone of claims 1 to 16, wherein the biocarbon content of the hot melt adhesive is greater than or equal to 60 %, preferably greater than or equal to 65 %, and even more preferably greater than or equal to 70 %.
  18. 18. The hot melt adhesive composition according to anyone of claims 1 to 17, wherein it has: a creep retention lower than or equal to 20%, more preferably lower than or equal to 15%, and even more preferably lower than or equal to 10%; and/or a Young Modulus higher than or equal to 2 MPa, more preferably higher than or equal to 4 MPa; and/or a Storage Modulus (G’) at 25°C higher than or equal to 100 kPa, more preferably higher than or equal to 500 kPa.
  19. 19. The use of the hot melt adhesive composition as defined in anyone of claims 1 to 18, as positioning adhesive, core adhesive or elastic attachment adhesive, more preferably as elastic attachment adhesive.
  20. 20. A laminate comprising at least one elastic material and at least two substrates, said elastic material being inserted between two substrates and covered with the hot melt adhesive composition as defined in anyone of claims 1 to 18.

Description

Hot melt adhesive TECHNICAL FIELD The present invention relates to hot melt adhesive in particular useful for disposable articles, and more particularly as elastic attachment adhesive. TECHNICAL BACKGROUND Hot melt adhesives (HM adhesives) are substances which are solid at room temperature and which comprise neither water nor solvent. They are applied in the molten state after heating to a temperature generally of between 120 and 250°C, most often between 130 and 180°C, and solidify during cooling, thus forming a seal (or adhesive joint) which ensures the attachment of the two substrates to be assembled. Hot melt adhesives are generally provided in the form of compositions which comprise a thermoplastic polymer and optionally a tackifying resin and a plasticizer. Among these HM adhesives, hot melt pressure sensitive adhesives (HMPSA) are substances conferring an immediate tackiness property (also called “tack”) to a substrate coated with such adhesive which allows its instantaneous adhesion to another substrate under a slight and brief pressure, at room temperature. Disposable hygiene articles are made from a wide variety of substrates (nonwoven, elastomeric material, film, such as polyolefin film and in particular polyethylene or polypropylene film) bonded with adhesive materials. Among examples of disposable hygiene articles, mention may be made of diapers, napkins or adult incontinence disposable articles. The disposable hygiene articles are produced at high speed line rates. In such production, hot melt adhesives are typically used because they can be easily applied to substrates (at the molten state) and rapidly develop strong bond upon cooling, without any additional manufacturing steps such as solvent removal. Several kinds of hot melt adhesives can be found in disposable hygiene articles, depending on their emplacement and final function, such as: ■ Core adhesives: used to keep in place the diaper core (fluff and SuperAbsorbentPolymer “SAP”), during the manufacture of the diaper but also during the use of the diaper mainly after that said diaper has been wet. ■ Construction adhesives: which bind the polyethylene back sheet to the nonwoven substrates or which bind two nonwoven substrates. ■ Elastic adhesives: used to bind elastic material (such as for example polyurethane based strands) to sheet-like substrates (such as for example polyethylene “PE” or to polypropylene “PP” and Nonwoven substrates). In particular, in elastic attachment applications, the adhesive should maintain the elastic material in place, particularly when solicited during manufacturing and use of the disposable hygiene article. Indeed, during the manufacture process, the elastic material (for example a set of elastic strands) is usually first stretched prior to bonding and then the adhesive is applied onto the elastic material, either by non-contact (spraying) or contact applications, then the elastic material coated with the adhesive are quickly laminated between two sheet-like substrates (for example a nonwoven substrate and a polyolefin film). After that, the elastic material is permitted to relax, creating a gathered (or rushed) laminate having substantial flexibility. The adhesive thus needs to present high cohesion and elasticity to be resistant enough to creep strength. Moreover, in order to avoid any adhesive failure, good adhesion on the elastic material is also recommended. Besides, conventional hot melt adhesives are petrochemical-based, and rely on energy-intensive processes. In addition, a large percentage of the petroleum is transported from various parts of the world, which increases the carbon footprint. Generally, zero to very few raw materials in hot melt adhesives are made from renewable resources and thus contribution is not enough on the impact of the environment. There is an increased desire to reduce carbon footprint and to produce environmentally sound products. One method of making an environmentally sound adhesive is to decrease carbon footprint by forming a hot melt adhesive from materials having a high renewable resource content. Besides, adhesives made from renewable materials do not necessarily allow to reach similar or better properties than conventional petroleum-based adhesives. There is thus a need for providing environment-friendly hot melt adhesives that allows to resolve at least a part of the above-mentioned drawbacks. There is a need for providing an environment-friendly hot melt adhesive composition exhibiting good adhesion properties on a variety of substrate materials and fabrics, and a low creep retention. There is a need for providing an environment-friendly hot melt adhesive composition exhibiting a good compromise between low creep retention, good adhesive properties, and good cohesive strength. There is a need for providing an environment-friendly hot melt adhesive composition exhibiting a good compromise between low creep retention, good adhesive properties, good cohesive strengt