Compostable hot melt adhesive

Abstract

The present invention provides a hot-melt adhesive composition for use in packaging materials that utilize renewable resource materials, such as paper, starch, and certain biodegradable plastics (aliphatic polyesters, polylactides, etc.). [Solution] The hot-melt adhesive comprises a polylactide homopolymer or copolymer, e.g., polylactic acid; sulfonated copolyester; and at least one plasticizer, and is compostable. The plasticizer may be a solid plasticizer, e.g., benzoate, and a second plasticizer may also be used. The adhesive is suitable for use in a variety of applications, such as cases and cartons, burlap or other compostable substrates for tree bulbs or plant seeds, and other compostable films, and is particularly suitable for double-walled cardboard beverage cups.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of U.S. Patent Application No. 62 / 728,424, filed Sep. 7, 2018, under 35 U.S.C. § 119(e).

[0002] The present invention relates to a hot - melt adhesive that is compostable and is adapted to be used as an adhesive for paperboard beverage cups, especially for both hot and cold beverages.

Background Art

[0003] Hot - melt adhesives are widely used in a variety of commercial applications. One advantage of hot - melt adhesives is that in their systems, no carrier fluid or solvent is required when applying to a substrate, and as a result, there is no need to evaporate a solvent or carrier fluid after application. The absence of a drying or evaporation process allows hot - melt adhesive systems to eliminate the risks associated with solvent use and the environmental impact of volatile organic compounds (VOCs). The use of hot - melt adhesives also reduces water consumption by not requiring water as part of the adhesive. The formulations of hot - melt adhesives can vary the performance of the adhesives widely, from pressure - sensitive to non - pressure - sensitive.

[0004] Hot - melt adhesives have conventionally been based on petroleum - derived polymers. Thermoplastic plastics are used as the polymer components of hot - melt adhesives, and they are generally classified into three types: (1) petroleum - derived polymers, such as polyethylene, polypropylene, ethylene - vinyl acetate, styrene block copolymers (e.g., styrene - isoprene - styrene, styrene - butadiene - styrene); (2) polyurethanes; and (3) polyester / polycarbonate materials.

[0005] Many of these products have the disadvantage of being poorly biodegradable in the environment. There is a strong demand for packaging materials that use renewable resources, such as paper, starch, and certain biodegradable plastics (aliphatic polyesters, polylactides, etc.). In the case of paper products, using environmentally biodegradable adhesives would allow the adhesive to be composted when paper, cardboard, or cardboard products are recycled. Alternatively, using environmentally biodegradable adhesives would allow the entire assembly to be composted, unlike articles sealed with typical petroleum-based hot-melt formulations.

[0006] For certain adhesive applications, the performance requirements are more stringent than usual. Adhesives that are compostable and perform well in cardboard beverage cups must fulfill several functions. For example, an adhesive used to seal cardboard beverage cups must function as an adhesive over a wide temperature range, depending on whether the cup contains a cold beverage (e.g., juice or soda) or a hot beverage (e.g., coffee or tea). For instance, the adhesive must meet the requirement that if hot water (e.g., approximately 180°F to 190°F) is placed in the cup, the result should be 100% fiber tearing across all seals (radial and endoscopic seals). In other words, there should be no cohesive failure or adhesive layer failure; the cup must tear first. Furthermore, this test must pass both initially (offline) and under aging conditions (i.e., 5 days at 72°F). In addition, the adhesive must be compostable without sacrificing adhesive performance. Furthermore, it is desirable that the hot melt adhesive can be used on existing hot melt adhesive application equipment, which means that it must have equivalent flow characteristics, including viscosity, at the applicable temperature.

[0007] Hot melt adhesives have been used to bond the outer wall of disposable paper cups used for beverages (e.g., coffee or tea) to other substrates (e.g., paper / labels) that function as a secondary wall. Conventionally, to bond a cup to a label, it is known to apply numerous radial beads of hot melt adhesive around the outer circumference of the cup, and seam beads (or end seals) along the length of the cup where the label edges make contact. A compostable hot melt adhesive with heat resistance to withstand hot beverage conditions (e.g., 180°F to 190°F) is not known on the market today. Furthermore, a compostable hot melt adhesive with a wide operating temperature range (e.g., 0°F to 160°F) is also not known on the market today.

[0008] U.S. Patent No. 5,753,724 discloses hot-melt adhesive compositions made using lactic acid-derived polyester. Thermoplastic-grade polyesters can be formulated with adhesive components to become functional adhesives. Low molecular weight substances can be used as thickening resins in formulated hot-melt adhesives using biodegradable / compostable resins. The adhesive substance can be pressure-sensitive and can also be made completely biodegradable by combining the polyester polymer with other biodegradable / compostable components. The adhesive compositions thus obtained can be used in a variety of applications. Biodegradable / compostable adhesive substances can be used as a substitute for non-biodegradable substances made from commercially available polymers that are resistant to attack by bacteria, fungi, and other microorganisms. These hot-melt adhesives can be used in packaging materials and in the manufacture of disposable articles made from biodegradable materials. Completely disposable articles can be made from adhesives and structural materials that are completely compostable.

[0009] U.S. Patent No. 7,868,101 discloses methods for preparing environmentally biodegradable polymer compounds, as well as such compounds themselves and their uses. The compounds of this invention comprise a polymer containing polycondensed lactic acid having a molecular weight (Mw) of 500 to 50,000 g / mol, to which an aliphatic polyester for softening, also having a molecular weight (Mw) of 500 to 50,000 g / mol, is combined. The amount of lactic acid-containing groups in the polymer compound ranges from 50 to 99%, and the amount of polyester groups for softening ranges from 1 to 50%. [Overview of the Initiative] [Means for solving the problem]

[0010] Embodiments of the present invention avoid many of the problems and limitations of the prior art. One embodiment of the present invention relates to a compostable hot-melt adhesive suitable for use in a variety of applications, such as cases and cartons, and particularly suitable for double-walled cardboard cups. The hot-melt adhesive composition of this embodiment comprises a polylactide homopolymer or copolymer; a sulfonated copolyester; and a plasticizer, and is compostable. The polylactide homopolymer or copolymer may be selected from the group consisting of polylactic acid and lactones, preferably glycolides and caprolactone copolymers. The plasticizer is preferably solid and may include a benzoate, preferably 1,4-cyclohexanedimethanol dibenzoate. The adhesive composition may include a second plasticizer, which may be selected from at least one of ethylene glycol, propylene glycol, and polyethylene glycol. The adhesive composition may further include an antioxidant, such as a hindered phenol. In one embodiment, the adhesive composition contains a component having a hydroxyl value greater than 100 mg KOH / g in an amount of 5% by weight or less, more preferably 4% by weight or less, and most preferably 3% by weight or less.

[0011] In another embodiment of the present invention, a method for forming a double-walled container is: (a) The step of applying the hot-melt adhesive composition of the present invention as described herein to the outer surface of a first generally cylindrical cardboard substrate in a molten state; (b) A step of fitting a second cardboard substrate, generally rectangular, onto a first cardboard substrate, wherein the second cardboard substrate is longer than the circumference of the first cardboard substrate, thereby providing an axial strip, and in the axial strip, the ends of the second cardboard substrate overlap; and (c) The step of applying a hot melt adhesive composition in a molten state to one of the mating surfaces of the axial strip; and (d) A process of fitting the mating surfaces of the axial strips to provide a double-walled container. Includes.

[0012] Another embodiment of the present invention relates to a container formed by the method of the present invention as described herein. In one aspect of this embodiment of the present invention, the cardboard used for the container is compostable, and the container is a drinking cup.

[0013] Embodiments of the present invention provide a compostable hot-melt adhesive having adhesive and heat resistance similar to conventional non-compostable hot-melt adhesives, such as those based on polyolefins, ethylene vinyl acetate, or styrene block copolymers. The adhesive according to the present invention is useful in a variety of end applications, such as cases and cartons, use with compostable films, use with tree bulbs or plant seeds wrapped in burlap or other compostable substrates, and the construction of various articles, such as the construction of double-walled beverage cups. With regard to its use in the construction of compostable double-walled beverage cups, the adhesive can be used to bond the outer wall surface of the inner substrate of a disposable paper cup to another outer substrate (e.g., paper / label) that functions as a secondary wall. Furthermore, the same adhesive can be used for both bonding the inner substrate to the outer substrate and for bonding the outer substrate in the end-seal area of ​​the secondary wall.

[0014] Those skilled in the art will understand the other features and advantages of the present invention by reading the following description. [Modes for carrying out the invention]

[0015] In one embodiment of the present invention, the hot-melt adhesive composition is compostable and comprises a homopolymer or copolymer of polylactide; a sulfonated copolyester; and a plasticizer.

[0016] The polylactide homopolymer or copolymer is selected from the group consisting of polylactic acid and lactones, preferably glycolides and caprolactone copolymers. In preferred embodiments, the polylactide homopolymer or copolymer contains, substantially contains, or consists of polylactic acid. In other embodiments, the polylactide homopolymer or copolymer has a melt index of at least 50 g / 10 min, preferably at least 55 g / 10 min, and most preferably at least 60 g / 10 min, at 210°C using 2.16 kg by weight, according to ASTM Method D1238. The polylactide homopolymer or copolymer has a melt index of at most 500 g / 10 min, preferably at most 200 g / 10 min, more preferably at most 150 g / 10 min, and most preferably at most 100 g / 10 min, at 210°C using 2.16 kg by weight, according to ASTM Method D1238.

[0017] In some embodiments, the polylactide homopolymer or copolymer contains at least 20 mole percent of lactide comonomer. The general structure of polylactide is shown below. [ka]

[0018] Suitable polylactide homopolymers or copolymers for use herein have a number-average molecular weight (Mn) in the range of 3,000 to 200,000 g / mol (all molecular weights mentioned herein are measured by gel permeation chromatography (GPC) using polystyrene standards). Poly(D,L-lactide) and its mesoforms are essentially amorphous, whereas poly(L-lactide) and poly(D-lactide) are essentially crystalline and have a crystalline melting point of 186°C depending on their molecular weight and stereopurity. These polymers can be prepared by ring-opening polymerization of a bicyclic ester of lactic acid using an acid or base catalyst, such as PbO, SnCl2, SnCl4, ZnCl2, SbF5, Sb2O3, or triethylamine, using solution, precipitation, or melt methods. Alternatively, they can be obtained commercially from Henley Chemicals, Inc. under the Resomer® trademark, or from Poly Sciences Inc. or Ecological Chemical Products Company (EcoChem).

[0019] In addition to poly(L-lactide) and poly(D-lactide) homopolymers, poly(D,L-lactide) and poly(meso-lactide) are also suitable polylactide homopolymers or copolymers for use herein and can be prepared by copolymerization with other lactones, such as glycolides or caprolactones. Poly(D,L-lactide-co-glycolide) polymers containing equal amounts of lactide and glycolide components are available from Henley Chemicals as Resomer® RG502, 503, 504, 505, and 506 and are suitable for use herein. Furthermore, poly(D,L-lactide-co-glycolide) polymers known as Resomer® RG752, 755, and 756 containing 75% lactide, and Resomer® 858 polymer containing 85% lactide, are also suitable.

[0020] In one embodiment, the polylactide homopolymer or copolymer is a thermoplastic resin derived from renewable raw materials. The polylactide homopolymer or copolymer is preferably amorphous and has a low melting point. In embodiments of the present invention, the specific gravity of the polylactide homopolymer or copolymer is about 1.1 to about 1.5, preferably about 1.15 to about 1.4, and most preferably about 1.2 to about 1.3, as measured according to ASTM D792. In embodiments of the present invention, the glass transition temperature of the polylactide homopolymer or copolymer is about 40°C to about 70°C, preferably about 45°C to about 65°C, and most preferably about 50°C to about 60°C, as measured according to ASTM D3417. In embodiments of the present invention, the melt index of a polylactide homopolymer or copolymer is at least about 50 g / 10 min at 210°C using a weight of 2.16 kg, preferably at least about 55 g / 10 min at 210°C using a weight of 2.16 kg, most preferably at least about 60 g / 10 min at 210°C using a weight of 2.16 kg, and it has a melt index of at most about 500 g / 10 min at 210°C using a weight of 2.16 kg, preferably at most about 200 g / 10 min at 210°C using a weight of 2.16 kg, more preferably at most about 150 g / 10 min at 210°C using a weight of 2.16 kg, most preferably at most about 100 g / 10 min at 210°C using a weight of 2.16 kg (all measured according to ASTM Method D1238). In all cases as specified herein, when multiple numerical values ​​are presented as both a lower limit and an upper limit for any property or concentration range, the present invention assumes any range that includes both any lower limit and any upper limit.

[0021] An example of a polylactide homopolymer or copolymer is the Vercet series of resins, particularly Vercet A1000, commercially available from Nature Works LLC. This is a thermoplastic resin derived from annually renewable raw materials, available in pellet form, and is amorphous, low-temperature meltable, and highly flowable.

[0022] The hot melt adhesive composition further contains a sulfonated copolyester. In an embodiment of the present invention, the specific gravity of the sulfonated copolyester is about 1 to about 1.5 g / cm 3 , preferably about 1.1 to about 1.3 g / cm 3 , most preferably about 1.2 to about 1.3 g / cm 3 . In an embodiment of the present invention, the glass transition temperature of the sulfonated copolyester is about 30°C to about 70°C, preferably about 35°C to about 60°C, most preferably about 40°C to about 50°C by a test method using DSC according to ASTM E1356-08, where the inflection point is determined as the midpoint of the inflection (secondary transition) during the second heating cycle. In an embodiment of the present invention, the intrinsic viscosity of the sulfonated copolyester is about 0.15 dL / g to about 0.45 dL / g, preferably about 0.2 dL / g to about 0.4 dL / g, most preferably about 0.25 dL / g to about 0.35 dL / g, measured according to ASTM D5225-14. In an embodiment of the present invention, the acid value of the sulfonated copolyester is either zero or at least about 0.01 mgKOH / g, preferably at least about 0.1 mgKOH / g, and at most about 10 mgKOH / g, preferably at most about 5 mgKOH / g, most preferably at most about 3 mgKOH / g. In an embodiment of the present invention, the hydroxyl value of the sulfonated copolyester is either zero or at least about 0.01 mgKOH / g, preferably at least about 0.1 mgKOH / g, and at most about 15 mgKOH / g, preferably at most about 10 mgKOH / g, most preferably at most about 5 mgKOH / g. In an embodiment of the present invention, the sulfonated copolyester has a weight average molecular weight of about 20,000 g / mol to 80,000 g / mol, preferably about 25,000 g / mol to 60,000 g / mol, most preferably about 28,000 g / mol to 42,000 g / mol. The viscosity of the polyester is preferably 1000 cP to 100,000 cP, most preferably 5000 to 60,000 cP at 350°F. The viscosity is measured using a Brookfield viscometer with a #27 spindle. Viscosity is generally related to molecular weight, and the higher the viscosity, the higher the corresponding molecular weight.

[0023] In embodiments of the present invention, the sulfonated copolyesters can be selected from those described in U.S. Patent No. 6,410,627 (this patent is incorporated herein by reference). This patent describes a. at least one difunctional dicarboxylic acid or corresponding methyl ester (which is not a sulfomonomer); b. 2 to 25 mole percent of at least one sulfomonomer containing at least one metal sulfonate group or nitrogen-containing non-metal sulfonate group bonded to an aromatic or alicyclic nucleus and at least one functional group selected from the group consisting of hydroxyl, carboxyl and amino; c. at least one difunctional reactant selected from a mixture of a glycol or a glycol and a diamine having two -NRH groups, or a glycol containing two -C(R1)2-OH groups, where R in the reactant is hydrogen or an alkyl group of 1 to 6 carbon atoms, and R1 in the reactant is a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or an aryl group of 6 to 10 carbon atoms; d. 0 to 40 mole percent of a difunctional reactant selected from a hydroxycarboxylic acid having one -C(R)2-OH group, an aminocarboxylic acid having one -NHR group, an amino - alcohol having one -C(R)2-OH group and one -NHR group, or a mixture of the difunctional reactants, where R in the reactant is hydrogen or an alkyl group of 1 to 6 carbon atoms; and e. 0 to 40 mole percent of a polyfunctional reactant containing at least three functional groups selected from hydroxyl, carboxyl and mixtures thereof, where at least a portion of the polyfunctional reactant contains at least three hydroxyl groups This invention describes condensed polymers containing reaction products, where all stated mole percents are based on the total of acid-containing, hydroxyl-containing, and amino-group-containing reactants (equal to 200 mole percent), where the polymer contains acid-containing reactants (100 mole percent of acid) in a ratio of hydroxyl- and amino-group-containing reactants (100 mole percent of base) such that the value obtained by dividing (equivalent value)EQ(base) by (equivalent value)EQ(acid) is 0.5 to 2. The polyester composition used as a component of the hot melt adhesive of this invention preferably includes (a) 60 to 100 mole percent, (b) 4 to 20 mole percent, (c) 80 to 100 mole percent, (d) 0 to 10 mole percent, and (e) 0 to 20 mole percent. In another more preferred embodiment of this invention, the polyester comprises 60 to 100 mole percent of 1,4-cyclohexanedicarboxylic acid; 4 to 20 mole percent of sodium 5-sodiosulfisophthalate or sodium dimethyl 5-sodiosulfisophthalate; and 80 to 100 mole percent of diethylene glycol, neopentyl glycol, or cyclohexanedimethanol.

[0024] In embodiments of the present invention, the sulfonated copolyester may be selected from those described in U.S. Patent No. 4,910,292, U.S. Patent No. 4,973,656, and U.S. Patent No. 4,990,593 (these patents are incorporated herein by reference). In yet another embodiment of the present invention, the sulfonated copolyester includes the Vitel® 1831044 copolyester polymer, commercially available from Bostik, Inc. Hot melt adhesives based on sulfonated copolyesters are described in U.S. Patent No. 5,750,605 (this patent is incorporated herein by reference). Examples of sulfonated copolyesters include the Eastman AQ series of solid copolyesters, commercially available from Eastman Chemical.

[0025] In embodiments of the present invention, the sulfonated copolyester is water-dispersible. Water dispersibility can be determined by the ability of the resin to disperse and remain as a homogeneous dispersion after mixing. This property can be determined by combining the product with water under heating (e.g., 95°C) and shearing. First, the resin is softened by heating (i.e., it is transparent and amorphous, but then becomes turbid and softens when mixed with water). If, upon completion of mixing, it does not settle or undergo phase separation under gravity, the product is said to be water-dispersible.

[0026] The use of sulfonated copolyesters offers the additional advantage of providing a degree of water sensitivity, which depends on the ionic strength of the aqueous environment. Therefore, the adhesive can be formulated to have sufficient resistance to the ionic environment encountered during use (e.g., exposure to bodily fluids encountered in diapers and sanitary napkins) and further to disperse and / or detach in tap water with lower ionic strength. Thus, these adhesives are particularly useful when constructing compostable articles.

[0027] The hot-melt adhesive composition further comprises a plasticizer. Preferably, the plasticizer is a solid plasticizer, which is particularly useful in embodiments requiring high heat resistance. Examples of solid plasticizers include benzoates. Benzoates can be selected from the group consisting of: glycerol tribenzoate, sucrose benzoate, pentaerythritol tetrabenzoate, and 1,4-cyclohexanedimethanol dibenzoate. Most preferably, the benzoate contains, is substantially derived from, or consists of 1,4-cyclohexanedimethanol dibenzoate, such as that commercially available from Eastman Chemical under the trademark Benzoflex 352. One disadvantage of using polylactide homopolymers or copolymers is their poor heat resistance. It has been found that incorporating a solid plasticizer into the formulation provides the heat resistance required for use as an adhesive for disposable cups used for hot beverages. Vegetable wax-based solid plasticizers are also suitable.

[0028] In one embodiment, the solid plasticizer has a melting point of about 80°C to about 160°C, preferably about 90°C to about 150°C, more preferably about 100°C to about 140°C, even more preferably about 110°C to about 130°C, and most preferably about 110°C to about 125°C, as measured according to ASTM D7138 using DSC. In embodiments of the present invention, the acid value of the solid plasticizer is either zero or at least about 0.001 mgKOH / g, preferably at least about 0.01 mgKOH / g, and at most about 3 mgKOH / g, preferably at most about 1 mgKOH / g, and most preferably at most about 0.2 mgKOH / g. In embodiments of the present invention, the hydroxyl value of the sulfonated copolyester is either zero or at least about 0.01 mg KOH / g, preferably at least about 0.1 mg KOH / g, and at most about 10 mg KOH / g, preferably at most about 5 mg KOH / g, and most preferably at most about 3 mg KOH / g.

[0029] In embodiments of the present invention, the adhesive further comprises a second plasticizer. The second plasticizer is selected from the group consisting of ethylene glycol, propylene glycol, and polyethylene glycol. Polyethylene glycol having a lower viscosity (e.g., PEG400) helps to lower the viscosity of the adhesive. Liquid plasticizers are particularly advantageous in embodiments where a solid plasticizer is used as the first plasticizer and it is necessary to lower the viscosity of the formulation. Depending on the desired viscosity of the formulation, a range of polyethylene glycols can be used.

[0030] Other plasticizers suitable for use in hot-melt adhesive compositions are described in U.S. Patent No. 5,753,724 (this patent is incorporated herein by reference). Plasticizers can improve the melting properties of adhesives, impart pressure sensitivity, reduce adhesive costs, and enhance the flexibility and melting properties of hot-melt adhesives. Preferred plasticizers for use with the hot-melt adhesives of the present invention are biodegradable / compostable plasticizers. Such plasticizers typically include naturally derived oils or esters, or synthetic substances manufactured containing urea carbamyl or amide groups. Plasticizers typically have a different molecular weight from the other components of the adhesive composition. If a solid plasticizer is used as the first plasticizer and it is necessary to reduce the viscosity of the formulation, a liquid plasticizer, for example, a substance having a molecular weight of less than about 5,000 g / mol, preferably less than 1,000 g / mol, can be used, which can impart plasticizing properties to the composition of the present invention. Preferred types of plasticizers for use in the present invention include natural oils and fats that are compatible with other components disclosed herein. More preferred types of plasticizers for use in the adhesives of the present invention include ester-based plasticizers, typically produced by reacting small aromatic or aliphatic monools, diols, or triols with aromatic or aliphatic acid compositions. Specific examples of additional plasticizers include: castor oil, TegMer 809-PEG400 di-2-ethylhexoate ester, Plathall DBS-dibutyl sebacate, Plathall DIBA diisobutyl sebacate, Santizer 160 (which is butyl benzyl phthalate), polycaprolactone diols having a molecular weight of about 500 g / mole and a melting point of less than about 25°C, ethylene glycol dibenzoate, propylene glycol dibenzoate, diethylene glycol dibenzoate, and dipropylene glycol dibenzoate.

[0031] In embodiments of the present invention, the adhesive further comprises a stabilizer or antioxidant. A useful stabilizer / antioxidant is incorporated into the hot-melt adhesive composition of the present invention to help protect the other components described above, and thus the entire adhesive system, from the effects of thermal and oxidative decomposition, which typically occur during the manufacture and application of the adhesive, and also during the normal exposure of the final product to the surrounding environment. The antioxidant may include a hindered phenol. The hindered phenol is selected from the group consisting of: 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 3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 4,4'-methylenebis(2,6-di-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; di-n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate; 2-(n-octylthio)-ethyl3,5-di-tert-butyl-4-hydroxybenzoate; and sorbitol hexa[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. The hot-melt adhesive of the present invention may further contain stabilizers and / or antioxidants in an effective amount, preferably about 0.1% to about 5% by weight. It is preferable that about 0.1% to 2% of stabilizers or antioxidants be incorporated into the composition. Among the applicable stabilizers, hindered phenols and multifunctional phenols, such as sulfur and phosphorus-containing phenols, are preferred.

[0032] Polyolefin nucleating agents may further be present in the adhesive of the present invention. Suitable nucleating agents for the present invention are generally subclasses of nucleating agents known as clarifying agents, which are commonly used in polyolefin additive packaging materials to promote rapid crystallization. Suitable substances include dibenzylidenesorbitol derivatives, such as Millad 3988 and Millad NX8000 supplied by Milliken, and Irgaclear D from BASF. Other suitable agents include aromatic amides, such as NJ Star NU-100 supplied by New Japan Chemical Company. If a nucleating agent is included, it is generally used in the adhesive composition in an amount of about 0.05 to 5% by weight, preferably about 0.1 to 2.5% by weight, and most preferably about 0.2 to 1.0% by weight. Blends of two or more nucleating agents may be used. For example, a blend of one nucleating agent and a second nucleating agent different from the first nucleating agent may be used. If necessary, the first nucleating agent may be blended with one or more additional nucleating agents in an amount of about 0.05% to about 5% by weight. The nucleating agents can be used directly as a powder, as part of a slurry of a suitable plasticizer, or as a component in a masterbatch of a suitable polymer, such as Milliken NX-10. Packaging of the nucleating agents, such as that described in U.S. Patent Application Publication No. 2015 / 0299526, may also be used to adjust the setup speed and adhesion of the hot melt adhesive.

[0033] It should be understood that any other additives may be incorporated into the adhesive composition of the present invention for the purpose of modifying specific physical properties. Such additives include, for example, ultraviolet (UV) absorbers, waxes, surfactants, inert colorants, titanium dioxide, fluorescent agents, and fillers. Typical fillers include talc, calcium carbonate, clay silica, mica, wollastonite, feldspar, aluminum silicate, alumina, hydrated alumina, glass microspheres, ceramic microspheres, thermoplastic microspheres, barite, and wood flour, which may be included in amounts up to 40% by weight, preferably 1 to 30% by weight.

[0034] The adhesives of the present invention are compostable. As used herein, the term “compostable” when applied to an adhesive means that the adhesive meets either of the following requirements: (1) a disintegration test as defined by ASTM D 6400-12 (using ISO 20200) (84 days of composting exposure), or (2) aerobic biodegradation as defined by ASTM D 6400-12 (using ASTM 5338-15) (58±2℃, 141 days). In other words, the adhesive either achieves a minimum weight loss of 90% within 84 days under disintegration test conditions, or achieves a carbon conversion rate (CO2 emission basis) of at least 90% within 141 days according to the aerobic biodegradation test, which will be described in more detail in the Examples section. In a preferred embodiment, the adhesive satisfies both of the following requirements: (1) a disintegration test defined by ASTM D 6400-12 (using ISO 20200) (84 days of composting exposure), and (2) aerobic biodegradation defined by ASTM D 6400-12 (using ASTM 5338-15) (58±2℃, 141 days).

[0035] It has been found that the relative amounts of various components are important for the adhesive to achieve the various properties required for the desired application. This is particularly true when the adhesive is used to seal two walls together in a beverage cup (which requires heat resistance, resistance over a wide temperature range, and compostability). In one embodiment, polylactic acid, sulfonated copolyester, and plasticizer are present in amounts effective to achieve at least 80%, preferably at least 90%, and most preferably 100% adhesive performance. As used herein, the term “adhesive performance” refers to the performance of the adhesive when applied to uncoated cardboard and tested in the following manner: a pleated flap was cut into 1.5” × 4” plate-like test pieces. The adhesive in the form of 3 / 8” beads was applied at 350°F with an open time of 2 seconds and pressure of 2 seconds. The adhesive was cured overnight at room temperature. Three adhesives prepared using each adhesive were placed in a 0°F freezer and a 160°F oven for 24 hours. After that time, the adhesives were removed and immediately tested for fiber tear percentage. The term "fiber tear" refers to the area of ​​the substrate torn relative to the area of ​​the adhesive broken, either adhesively or cohesively. In preferred embodiments, polylactic acid, sulfonated copolyester, and solid plasticizer are present in amounts effective to achieve the above-described adhesive performance at a temperature of about 175°F, most preferably over a temperature range of 0°F to 175°F. In other embodiments, polylactic acid and sulfonated copolyester are present in a weight ratio of about 1:1 to about 9:5, preferably about 6:5 to 8:5, most preferably about 13:10 to about 3:2.

[0036] In embodiments of the present invention, the formulation comprises the following components in approximately the following weight percentages: Polylactic acid is present in an amount that functions as a base polymer to give cohesiveness to the adhesive, and in some embodiments is present in an amount of about 25 to about 43% by weight, preferably about 30 to about 38% by weight, most preferably about 31 to about 37% by weight; The sulfonated copolyester is present in an amount effective to act as an adhesion promoter for porous substrates, such as cardboard or labels, and in some embodiments is present in an amount of about 15 to about 35% by weight, preferably about 20 to about 30% by weight, most preferably about 22 to about 28% by weight; The plasticizer is present in an amount effective to improve the heat resistance of the formulation to a desired level (e.g., the aforementioned adhesive performance at high temperatures), and in some embodiments is present in an amount of about 5 to about 60% by weight, preferably about 15 to about 55% by weight, more preferably about 20 to about 50% by weight, and most preferably about 36 to about 42% by weight; and When used, the second plasticizer is present in an amount effective in reducing the viscosity of the adhesive to a desired value, and in some embodiments is present in an amount of about 1 to 5% by weight, preferably about 1.3 to 3% by weight, and most preferably about 1.5 to 2% by weight; When used, an antioxidant, such as a hindered phenol, is present in an amount effective to prevent oxidation or stabilize the adhesive, and in some embodiments, the antioxidant is present in an amount of about 0.1 to about 1% by weight, preferably about 0.25 to about 0.75% by weight, and most preferably about 0.4 to about 0.6% by weight.

[0037] The composition preferably contains a component having a hydroxyl value greater than 100 mg KOH / g in an amount of 5% by weight or less, more preferably about 4% by weight or less, and most preferably about 3% by weight or less. Such components may be, for example, styrene allyl copolymers, orthophthalate neopentyl glycols, polyester polyols, or combinations thereof, as disclosed in U.S. Patent No. 6,410,627 (which is incorporated herein by reference).

[0038] In preparing the adhesive composition of the present invention, no specific sequence is required, and it can be prepared using conventional process steps. The adhesive may be prepared by mixing various components and then heating it immediately before application to the substrate.

[0039] The viscosity of the adhesive material according to the present invention should generally be the viscosity at the application temperature suitable for processing and application to the substrate as a hot-melt adhesive. To process with a standard hot-melt bonding apparatus, obtain the desired pattern, and consequently exhibit appropriate adhesive performance at the application temperature, an adhesive with a relatively low viscosity at a low application temperature is required. Generally, the viscosity, measured according to ASTM D3236, is about 50,000 cP or less at the application temperature, preferably about 40,000 cP or less, more preferably about 35,000 cP or less, and even more preferably about 30,000 cP or less. All viscosities specified herein are measured according to this modified ASTM standard. The viscosity of the composition is preferably at least 1,000 cP, more preferably at least 5,000 cP, even more preferably at least about 7,500 cP, and most preferably at least about 15,000 cP at the application temperature. Therefore, the viscosity may be 1,000 cP to 35,000 cP and 5,000 cP to 20,000 cP at 121°C. In other embodiments, the viscosity of the composition is among any range considered herein at various typically used application temperatures, the value of which depends on the specific application of the adhesive, 121°C to 180°C, for example, 121°C, 127°C, 135°C, 149°C and 177°C. In one embodiment where the adhesive is used to bond double-walled cups for hot beverages, the viscosity of the adhesive is preferably about 5,000 cP to about 50,000 cP, more preferably about 15,000 cP to about 35,000 cP, and most preferably about 20,000 cP to about 30,000 cP at 177°C.

[0040] The requirements for end-use applications are an important consideration in determining the desired softening point of the adhesive formulation. For applications where the adhesive is used to bond double-walled cups for hot beverages, the ring-spherical softening point of the adhesive, as measured according to ASTM E28-99, is about 180°F to about 300°F, more preferably about 200°F to about 280°F, and most preferably about 220°F to about 260°F.

[0041] Hot melt adhesives can be applied to substrates using a variety of coating methods. Examples include: hot melt slot die coating, hot melt wheel coating, hot melt roller coating, melt blow coating, and also slotting, spiral spraying, and wrapping spraying methods, which are used, for example, to bond elastic strands. Many spraying methods exist and can be carried out with or without the assistance of compressed air, which will form a spray pattern of the adhesive. The hot melt adhesive material is generally pumped through a hose to the final coating spot on the substrate.

[0042] In one embodiment of the present invention, a method for forming a double-walled container is: (a) The step of applying the hot melt adhesive composition described herein to the outer surface of a first generally cylindrical cardboard substrate in a molten state; (b) A step of fitting a second cardboard substrate, generally rectangular, onto a first cardboard substrate, wherein the second cardboard substrate is longer than the circumference of the first cardboard substrate, thereby providing an axial strip, and in the axial strip, the ends of the second cardboard substrate overlap; and (c) The step of applying a hot melt adhesive composition in a molten state to one of the mating surfaces of the axial strip; and (d) A process of fitting the mating surfaces of the axial strips to provide a double-walled container. Includes.

[0043] In one embodiment of the present invention, step (a) includes applying a hot-melt adhesive in a radial pattern. In other embodiments, steps (a) and (c) include applying a hot-melt adhesive composition in the form of beads. The cardboard is preferably compostable. It is even more preferable that the cardboard used for the container is compostable and the container is a drinking cup. One such double-walled container is described in U.S. Patent No. 6,109,518 (this patent is incorporated herein by reference).

[0044] The compostable hot-melt adhesive of the present invention can be used in many applications, particularly where it is desirable that the final article (including the adhesive) be compostable. As previously stated, embodiments of the adhesive of the present invention are particularly suitable for double-walled cardboard beverage cups. Examples of other applications include: cases and cartons; use with burlap or other compostable substrates for tree bulbs or plant seeds; and use with other compostable films. In each of these, the adhesive is applied in a molten state to a first substrate, then a second substrate (or a part of the first substrate) is brought into contact with the adhesive, and then, as it cools, the first substrate is bonded to the second substrate (or the other part of the first substrate that is placed on top of and fitted to the first substrate). For example, in one embodiment, tree bulbs or plant seeds are wrapped in compostable burlap, the adhesive is applied to the fitting portion of the burlap, and then the burlap is placed on top of itself so that the two fitting surfaces of the burlap bond to each other as the hot-melt adhesive cools. In another embodiment, a first compostable film or substrate is brought into contact with the adhesive of the present invention, then a second compostable film is brought into contact with the adhesive, and the two compostable films are cooled so that they are bonded together to form a compostable laminate.

[0045] Embodiments of the present invention Embodiment 1. A hot melt adhesive composition, (a) homopolymers or copolymers of polylactide; (b) Sulfonated copolyesters; and (c) Plasticizer A hot-melt adhesive composition containing the adhesive, which is compostable. Embodiment 2. The composition according to Embodiment 1, wherein the polylactide homopolymer or copolymer is selected from the group consisting of polylactic acid and lactones, preferably glycolides and caprolactone copolymers. Embodiment 3. The composition according to Embodiment 1, wherein the polylactide homopolymer or copolymer contains, substantially contains, or consists of polylactic acid. Embodiment 4. The composition according to any one of Embodiments 1 to 3, wherein the polylactic acid, sulfonated copolyester, and plasticizer are present in an amount effective to achieve an adhesive performance of at least 80%, preferably at least 90%, and most preferably 100%. Embodiment 5. The composition according to Embodiment 4, wherein the polylactic acid, sulfonated copolyester, and solid plasticizer are present in amounts effective to achieve adhesive performance at a temperature of about 175°F, most preferably over a temperature range of 0°F to 175°F. Embodiment 6. The composition according to any one of Embodiments 1 to 5, wherein the polylactic acid homopolymer or copolymer and the sulfonated copolyester are present in a weight ratio of about 1:1 to about 9:5, preferably about 6:5 to about 8:5, and most preferably about 13:10 to about 3:2. Appearance 7.(a) The polylactide homopolymer or copolymer is present in an amount of about 25 to about 43% by weight, preferably about 30 to about 38% by weight, most preferably about 31 to about 37% by weight; (b) The sulfonated copolyester is present in an amount of about 15 to about 35% by weight, preferably about 20 to about 30% by weight, most preferably about 22 to about 28% by weight; and (c) The composition according to any one of embodiments 1 to 6, wherein the plasticizer is present in an amount of about 5 to about 60% by weight, preferably about 15 to about 55% by weight, more preferably about 20 to about 50% by weight, and most preferably about 36 to about 42% by weight. Embodiment 8. The composition according to any one of Embodiments 1 to 7, wherein the sulfonated copolyester is water-dispersible. Embodiment 9. The composition according to any one of Embodiments 1 to 8, wherein the plasticizer includes a solid plasticizer. Embodiment 10. The composition according to Embodiment 9, wherein the solid plasticizer comprises a benzoate. Embodiment 11. The composition according to Embodiment 10, wherein the benzoate is selected from the group consisting of glycerol tribenzoate, sucrose benzoate, pentaerythritol tetrabenzoate, and 1,4-cyclohexanedimethanol dibenzoate. Embodiment 12. The composition according to Embodiment 10, wherein the benzoate comprises, substantially comprises, or consists of 1,4-cyclohexanedimethanoldibenzoate. Embodiment 13. The composition according to any one of Embodiments 1 to 12, further comprising a second plasticizer. Embodiment 14. The composition according to Embodiment 13, wherein the second plasticizer is selected from the group consisting of ethylene glycol, propylene glycol, and polyethylene glycol. Embodiment 15. The composition according to Embodiment 13 or 14, wherein the second plasticizer is present in an amount of about 1 to 5% by weight, preferably about 1.3 to about 3% by weight, and most preferably about 1.5 to about 2% by weight. Embodiment 16. The composition according to any one of Embodiments 1 to 15, further comprising an antioxidant. Embodiment 17. The composition according to Embodiment 16, wherein the antioxidant comprises, substantially comprises, or consists of a hindered phenol. Appearance 18. Hindered phenols include 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; pentaerythritol tetrakis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; n-octadecyl 3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 4,4'-methylenebis(2,6-di-tert-butylphenol); 4,4'-thiobis(6-tert-butyl-o-cresol); The composition according to embodiment 17, selected from the group consisting of 2,6-di-tert-butylphenol; 6-(4-hydroxyphenoxy)-2,4-bis(n-octylthio)-1,3,5-triazine; di-n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate; 2-(n-octylthio)-ethyl3,5-di-tert-butyl-4-hydroxybenzoate; and sorbitol hexa[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Embodiment 19. The composition according to any one of Embodiments 16 to 18, wherein the antioxidant is present in an amount of about 0.1 to about 1% by weight, preferably about 0.25 to about 0.75% by weight, and most preferably about 0.4 to about 0.6% by weight. The composition according to any one of embodiments 1 to 19, comprising 0.5% by weight, more preferably 4% by weight, and most preferably 3% by weight or less of a component having a hydroxyl value greater than 100 mg KOH / g. Embodiment 21. The composition according to any one of Embodiments 1 to 20, wherein the sulfonated copolyester has a weight-average molecular weight of about 20,000 g / mol to 80,000 g / mol, preferably about 25,000 g / mol to 60,000 g / mol, and most preferably about 28,000 g / mol to 42,000 g / mol. Embodiment 22. The composition according to any one of Embodiments 1 to 21, wherein the polylactide homopolymer or copolymer has a melt index of at least 50 g / 10 min, preferably at least 55 g / 10 min, and most preferably at least 60 g / 10 min, at 210°C using 2.16 kg by weight according to ASTM Method D1238. Embodiment 23. The adhesive is a composition according to any one of Embodiments 1 to 22, which satisfies both the requirements of (1) a disintegration test as defined by ASTM D 6400-12 (using ISO 20200) and (2) aerobic biodegradation as defined by ASTM D 6400-12 (using ASTM 5338-15). Embodiment 24. The composition according to any one of Embodiments 1 to 23, wherein the adhesive has a ring-spherical softening point determined by ASTM E28-99, which is about 180°F to about 300°F, more preferably about 200°F to about 280°F, and most preferably about 220°F to about 260°F. Embodiment 25. A method for forming a double-walled container, (a) A step of applying a hot melt adhesive composition according to any of embodiments 1 to 24 to the outer surface of a first generally cylindrical cardboard substrate in a molten state; (b) A step of fitting a second cardboard substrate, generally rectangular, onto a first cardboard substrate, wherein the second cardboard substrate is longer than the circumference of the first cardboard substrate, thereby providing an axial strip, and in the axial strip, the ends of the second cardboard substrate overlap; and (c) The step of applying a hot melt adhesive composition in a molten state to one of the mating surfaces of the axial strip; and (d) A process of fitting the mating surfaces of the axial strips to provide a double-walled container. A method that includes this. Embodiment 26. The method of Embodiment 25, wherein step (a) includes applying a hot melt adhesive in a radial pattern. Embodiment 27. The method according to Embodiment 25 or 26, wherein steps (a) and (c) include applying a hot-melt adhesive composition in the form of beads. Embodiment 28. The method according to any one of Embodiments 25 to 27, wherein the cardboard is compostable. Embodiment 29. A container formed by any of the methods described in Embodiments 25 to 28. Embodiment 30. The container according to Embodiment 29, wherein the cardboard used for the container is compostable, and the container is a drinking cup. [Examples]

[0046] The following examples illustrate some preferred embodiments of the present invention, but these examples should not be construed as limiting the present invention.

[0047] The feasibility of using the adhesive according to the present invention for double-walled beverage cups was investigated. Specifically, three formulations were tested for adhesive performance according to the following criteria.

[0048] The adhesive components shown in Table 1 below were mixed at room temperature and then heated. The molten adhesive was heated to 350°F and then applied in the form of radial beads to the uncoated cardboard wall on the outside of the cup. The outer wall of a commercially available cardboard cup was attached to the inner wall by fitting the outer wall into the adhesive that had just been applied to the inner wall. Another labial bead was applied to one of the mating surfaces of the second wall, in the portion of the second wall where the second surfaces overlap themselves to form an axial strip. The second wall was then attached to itself by fitting the mating surfaces of the axial strip. The labial beads (adhesive around the inner wall of the cup) create a gap between the inner and outer walls, providing insulation. The adhesive was applied at 350°F using a conventional adhesive application device.

[0049] The adhesive strength was measured by peeling off the end seal and checking for 100% fiber tearing (i.e., only the wall surfaces tore by themselves, and the adhesive remained intact). Heat resistance was tested by pouring hot water into a cup for one minute immediately after applying the adhesive. To pass the test, the end seal must not delaminate from top to bottom. The adhesive strength under 0°F and boiling water conditions was compared to a conventional hot-melt adhesive used as a control.

[0050] The components used, as shown in Table 1, are: polylactic acid ("PLA") sold by Nature Works LLC under the trademark Vercet A1000; sulfonated copolyester ("sulfonated copolyester") sold by Bostik, Inc. under the trademark Vitel® 1831044; solid plasticizer ("solid plasticizer") sold by Eastman Chemical under the trademark Benzoflex 352; liquid plasticizer sold by Dow Chemical under the trademark Carbowax Sentry PEG 400; and commonly used antioxidants ("AO"). Table 1 shows the weights (in grams) of each component. As can be seen, formulation 1 contains approximately 30% by weight of solid plasticizer. Formulation 1 did not pass the hot water test desired for this application. Formulation 2, which contains more solid plasticizer than formulation 1 but no liquid plasticizer, exhibited extremely good adhesion immediately after offline application and passed the hot water test, in contrast to formulation 1. However, after 10 minutes at room temperature, the adhesive became brittle and failed adhesively for both radial and end-seal applications. Formulation 3 passed adhesive strength tests both offline and over time (1 day, 5 days, 2 months; at various temperatures (0, 40, 72, 140, 160°F)).

[0051] Furthermore, surprisingly, mixture 3 exhibited a wider operating temperature range (0°F to 160°F) and boiling water conditions (3.0 minutes in a microwave, approximately 210°F water temperature). Although formulations 1 and 2 did not meet the stringent requirements of this application (i.e., cups for hot beverages), these formulations may be suitable for other applications requiring a compostable adhesive.

[0052] [Table 1]

[0053] An analysis was conducted to determine whether the adhesive composition of formulation 3 met the requirements for a disintegration test as defined by ASTM D 6400-12 (using ISO 20200). Specifically, a drawdown film of this adhesive with a maximum thickness of 31.5 mg was evaluated using ISO 20200 (up to 84 days at 58±2°C) in accordance with ASTM D 6400-12. The composted material in this test had a carbon-to-nitrogen ratio of 30:1, which is within the specified range for this test. The pH of the composted material at the start of the test was approximately 7.0, and the total dry solids content after drying to constant weight at 105°C was 44.5%. The mature mushroom compost used in the test was purchased from Monterey Mushrooms (Princeton, Illinois) and used in its as-received state, and it had a C:N ratio of 13:1. To meet this requirement, the test sample must achieve a minimum weight loss of 90% within the 84-day test period. The tested adhesive sample had completely decomposed after 84 days (100% weight loss).

[0054] An analysis was conducted to determine whether the adhesive composition of formulation 3 met the requirements for aerobic biodegradation as defined by ASTM 5338-15. Specifically, the mineralization of the aerobic biodegradation-exposed adhesive sample according to ASTM D 6400-12 (two-stage test) was evaluated using the mineralization according to ASTM D-5338-15 at 58±2°C by contact with a composting medium. The laboratory raw material compost used in the test had a C:N ratio of 29:1, which is within the specified range for this test. The pH of the composted material at the start of the test was approximately 7.0, and the total dry solids content after drying to constant weight at 105°C was 50.0%. The mature mushroom compost used in the test was purchased from Monterey Mushrooms (Princeton, Illinois) and used in its as-received state, and it had a C:N ratio of 14:1. To meet this requirement, the samples subjected to testing must achieve a minimum carbon conversion rate of 70% within 45 days of inorganicization according to ASTM D 5338-15, and a carbon conversion rate of 90% within 141 days of inorganicization according to ASTM D 5338-15. The tested adhesive samples met both of these requirements by achieving an average carbon conversion rate of 91.83% over 141 days.

[0055] When a range of values ​​is given, it should be understood that the intermediate values ​​between the upper and lower limits of that range, any combination or secondary combination of intermediate values, and any other described or intermediate values ​​within the described range are included within the stated range of values. In addition, the present invention includes the lower limit of the first range and the upper limit of the second range for that component.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art in which the invention pertains. All publications and patents specifically cited herein, including descriptions and disclosures of chemical products, instruments, statistical analyses, and methodologies described herein that may be used in connection with the invention, are incorporated by reference in their entirety for all purposes. Nothing herein should be construed as acknowledging that the invention is not entitled to precede any prior disclosure on the grounds of a prior invention.

[0057] Although this specification has described and explained with reference to certain specific embodiments, it is not intended to limit the invention to the details presented. Rather, various modifications in detail can be made within the scope of equivalents of the claims and without departing from the spirit of the invention.

Claims

1. A hot melt adhesive composition, (a) Homopolymers or copolymers of polylactides; (b) sulfonated copolyesters; and (c) A first plasticizer which is a solid plasticizer. (d) A second plasticizer selected from the group consisting of ethylene glycol, propylene glycol, and polyethylene glycol. A hot melt adhesive composition comprising the above, wherein the hot melt adhesive composition is compostable.

2. The composition according to claim 1, wherein the homopolymer or copolymer of the polylactide is selected from the group consisting of polylactic acid and lactone.

3. The composition according to claim 1, wherein the homopolymer or copolymer of the polylactide comprises polylactic acid.

4. The composition according to claim 3, wherein the polylactic acid, the sulfonated copolyester, and the first plasticizer are present in amounts effective for achieving at least 80% adhesive performance.

5. The composition according to claim 4, wherein the polylactic acid, the sulfonated copolyester, and the first plasticizer are present in amounts effective for achieving the adhesive performance over a temperature range of 0°F to 175°F (-17.8°C to 79.4°C).

6. The composition according to claim 3, wherein the polylactic acid and the sulfonated copolyester are present in a weight ratio of 1:1 to 9:

5.

7. (a) The polylactic acid is present in an amount of 25 to 43% by weight; (b) The sulfonated copolyester is present in an amount of 15 to 35% by weight; and (c) The composition according to claim 3, wherein the first plasticizer is present in an amount of 5 to 60% by weight.

8. The composition according to claim 1, wherein the sulfonated copolyester is water-dispersible.

9. The composition according to claim 1, wherein the first plasticizer comprises a benzoate.

10. The composition according to claim 9, wherein the benzoate is selected from the group consisting of glycerol tribenzoate, sucrose benzoate, pentaerythritol tetrabenzoate, and 1,4-cyclohexanedimethanol dibenzoate.

11. The composition according to claim 9, wherein the benzoate comprises 1,4-cyclohexanedimethanoldibenzoate.

12. The composition according to claim 1, wherein the second plasticizer is present in an amount of 1 to 5% by weight.

13. The composition according to claim 1, wherein the sulfonated copolyester has a weight-average molecular weight of 20,000 g / mol to 80,000 g / mol.

14. The composition according to claim 1, wherein the polylactide homopolymer or copolymer has a melt index of at least 50 g / 10 min at 210°C using 2.16 kg by weight, according to ASTM method D1238.

15. The hot melt adhesive composition according to claim 1, wherein the composition satisfies both requirements of (1) a disintegration test as defined by ASTM D 6400-12 (using ISO 20200) and (2) aerobic biodegradation as defined by ASTM D 6400-12 (using ASTM 5338-15).

16. The hot melt adhesive composition according to claim 1, wherein the hot melt adhesive composition has a ring-spherical softening point of 180°F to 300°F (82.2°C to 148.9°C) as determined by ASTM E28-99.

Images