Compostable hot melt adhesive

Abstract

The invention relates to a compostable hot melt adhesive. A hot melt adhesive includes: a polylactide homopolymer or copolymer, such as polylactic acid; sulfonated copolyester; and at least one plasticizer; and is compostable. The plasticizer may be a solid plasticizer, such as a benzoate, and a second plasticizer may also be used. The adhesives are suitable for use in a variety of applications, such as box and carton applications, for use with burlap or other compostable substrates for tree bulbs or plant seeds, and for use with other compostable films, and are particularly suitable for use with double wallpaper board beverage cups. The adhesives exhibit good adhesive properties comparable to non-compostable adhesives over a temperature range reflecting the temperature of hot and cold beverages.

Description

[0001] This application is a divisional application of the Chinese national phase patent application with international application number PCT / US2019 / 049897, international application date September 6, 2019, and invention name “Compostable Hot Melt Adhesive”, which entered the Chinese national phase on March 5, 2021 and has application number 201980058092.X.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. patent application No. 62 / 728,424, filed on September 7, 2018, under 35 U.S.C. §119(e). Technical Field

[0004] The present invention relates to a hot melt adhesive that is compostable and is particularly suitable for use as an adhesive for paperboard beverage cups for both hot and cold beverages. Background Art

[0005] Hot melt adhesives are used in a variety of commercial applications. An advantage of hot melt adhesives is that these systems do not require a carrier fluid or solvent to be applied to the substrate, and therefore eliminate the need for subsequent evaporation of solvents or carrier fluids. There is no drying or evaporation step to eliminate the environmental impact of the hazards associated with the use of solvents and volatile organic compounds (VOCs). Since water is not needed as a part of the adhesive, the use of hot melt adhesives also reduces water consumption. Hot melt adhesive formulations can change in a wide adhesive property range from pressure-sensitive to non-pressure-sensitive.

[0006] Hot melt adhesives have traditionally been based on petroleum-based polymers. Thermoplastics have been used as the polymer component of hot melt adhesives and are generally classified into three types: (1) petroleum-based 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.

[0007] Many of these products have the disadvantage of poor environmental degradability. There is a strong demand for packaging materials in which renewable resource materials like paper, starch and certain degradable plastics (aliphatic polyesters, polylactides, etc.) are used. In the case of paper products, the use of environmentally degradable adhesives will allow the adhesive to be composted when the paper, paperboard or carton product is recycled. Or alternatively, unlike products sealed with typical petroleum-based hot melt formulations, the use of environmentally degradable adhesives will allow the entire assembled product to be composted.

[0008] Certain adhesive applications have more demanding requirements than others, and an adhesive that is compostable and used in a paperboard beverage cup must have several functions. For an adhesive to be used to seal a paperboard beverage cup, it must be able to be used as an adhesive over a range of temperatures, taking into account that the cup may contain a cold beverage, such as juice or soda, or a hot beverage, such as coffee or tea. For example, the adhesive must meet performance requirements where the cup is filled with hot water (e.g., about 180°F-190°F) and torn, then the result must be 100% fiber tearing on all seals (both radial and end seals) of the adhesive. In other words, there must be no cohesive failure or adhesive failure; the cup must be torn first. In addition, this test must be passed both initially (offline) and after aging conditions (i.e., 5 days at 72°F). In addition, the adhesive must be compostable without compromising its bonding properties. In addition, it is desirable to allow the hot melt adhesive to run on existing hot melt adhesive application equipment, which means that it must have similar flow characteristics, including viscosity, at the application temperature.

[0009] Hot melt adhesives have been used to bond together the outer wall of a disposable paper cup for holding a beverage such as coffee or tea and another substrate (e.g., paper / label) that serves as a second wall. To bond the cup to the label, it is known to apply multiple radial hot melt adhesive beads around the periphery of the cup and apply a seam bead (or end seal) along the length of the cup where the edges of the label meet. There are no known compostable hot melt adhesives on the market today that have acceptable heat resistance to hot beverage conditions (e.g., at 180°F-190°F). There are also no known compostable hot melt adhesives on the market today that have a wide use temperature, e.g., (0°F-160°F).

[0010] U.S. Patent No. 5,753,724 discloses a hot melt adhesive composition, which is made using a polyester derived from lactic acid. Thermoplastic resin-grade polyester is formulated into a functional adhesive using an adhesive component. In the formulated hot melt adhesive, a relatively low molecular weight material can be used as a tackifying resin together with a biodegradable / compostable resin. By combining a polyester polymer with other biodegradable / compostable ingredients, the adhesive material can be made pressure-sensitive and fully degradable. The resulting adhesive composition can be used in a variety of applications. Biodegradable / compostable adhesive materials can be used as substitutes for non-biodegradable materials made from commercial polymers that resist attacks from bacteria, fungi, and other microbial populations. Hot melt adhesives can be used for packaging and manufacturing disposable products made from degradable materials. The entire disposable product can be made from fully compostable adhesives and structural materials.

[0011] U.S. Patent No. 7,868,101 discloses a method for preparing an environmentally degradable polymer, as well as such a compound itself and its use. The compound of the present invention includes a polymer containing polycondensed lactic acid, which has a molecular weight (Mw) from 500 to 50,000 g / mol, coupled with a toughening aliphatic polyester having a molecular weight from 500 to 50,000 g / mol. The amount of groups including lactic acid in the polymer ranges from 50% to 99%, and the amount of toughening polyester groups ranges from 1% to 50%. Summary of the invention

[0012] Embodiments of the present invention avoid many problems and limitations of the prior art. One embodiment of the present invention relates to a compostable hot melt adhesive suitable for a variety of applications, such as box and carton applications, and is particularly suitable for double-walled wallboard 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 a copolymer of lactones, preferably glycolide and caprolactone. 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 also include an antioxidant, such as a hindered phenol. In an embodiment, the adhesive composition comprises no more than 5wt%, more preferably no more than 4wt%, and most preferably no more than 3wt% of a component having a hydroxyl value greater than 100mg KOH / g.

[0013] According to another embodiment of the present invention, a method for forming a double-walled container includes the following steps:

[0014] (a) applying a hot melt adhesive composition of the present invention as described herein in a molten state to an outer surface of a first generally cylindrical paperboard substrate;

[0015] (b) joining a second generally rectangular paperboard substrate to the first paperboard substrate, wherein the second paperboard substrate is longer in circumference than the first paperboard substrate, thereby providing an axial strip of the second paperboard substrate with overlapping ends; and

[0016] (c) applying the hot melt adhesive composition in a molten state to one of the mating surfaces of the axial strips; and

[0017] (d) joining the joined surfaces of the axial strips to provide the double-walled container.

[0018] Another embodiment of the invention is directed to a container formed by the method of the invention as described herein. In an aspect of this embodiment of the invention, the paperboard used for the container is compostable and the container is a beverage cup.

[0019] Embodiments of the present invention provide a compostable hot melt adhesive having similar bonding properties and heat resistance characteristics 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 can be used in various terminal applications such as box and carton applications, used with compostable films, used with 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 of the inner substrate of a disposable paper cup to another outer substrate (e.g., paper / label) used as a second wall. In addition, the same adhesive can be used to bond the inner substrate to the outer substrate and to bond the outer substrate itself together at the end seal area of ​​the second wall.

[0020] Other features and advantages of the present invention may be apparent to those of ordinary skill in the art after reading the following description. DETAILED DESCRIPTION

[0021] According to an embodiment of the present invention, a hot melt adhesive composition is compostable and includes a polylactide homopolymer or copolymer; a sulfonated copolyester; and a plasticizer.

[0022] The polylactide homopolymer or copolymer is selected from the group consisting of: polylactic acid; and a copolymer of lactones, preferably glycolide and caprolactone. In a preferred embodiment, the polylactide homopolymer or copolymer comprises, consists essentially of, 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 a 2.16 kg 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 a 2.16 kg weight according to ASTM method D1238.

[0023] In an embodiment, the polylactide homopolymer or copolymer contains at least 20 mole percent of lactide comonomer. The general structure of polylactide is shown below:

[0024]

[0025] Suitable polylactide homopolymers or copolymers for use herein may 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.) While poly(D,L-lactide) and meso-lactide are essentially amorphous, poly(L-lactide) and poly(D-lactide) are crystalline in nature and have a crystalline melting point of 186°C based on their molecular weight and stereo purity. The polymers may be prepared by catalysis with an acid or base catalyst such as PbO, SnCl 2 SnCl 4 、ZnCl 2 , SbF 5 , Sb 2 O 3 or triethylamine, using solution, precipitation or melt methods. Alternatively, they can be obtained from Henley Chemicals, Inc. Commercially available under the trade name Polymer®; commercially available from Poly Sciences Inc. or Ecological Chemical Products Company (EcoChem).

[0026] In addition to homopolymers of poly(L-lactide), poly(D-lactide), poly(D,L-lactide) and poly(meso-lactide) are also suitable polylactide homopolymers or copolymers for use herein and can also be prepared by copolymerization with other lactones such as glycolide or caprolactone. Poly(D,L-lactide-co-glycolide) polymers containing equimolar amounts of lactide and glycolide components are available from Henry Chemical Company as RG502, 503, 504, 505 and 506 are obtained and are suitable for use herein. In addition, a poly (D, L-lactide-co-glycolide) polymer (referred to as RG752, 755 and 756) and 85% lactide 858 polymer is also suitable.

[0027] In one embodiment, polylactide homopolymer or copolymer is a thermoplastic resin derived from renewable resources. Preferably, polylactide homopolymer or copolymer is amorphous and has a low melting point. In an embodiment of the present invention, according to ASTM D792, the specific gravity of polylactide homopolymer or copolymer is between about 1.1 and about 1.5, preferably between about 1.15 and about 1.4, and most preferably between about 1.2 and about 1.3. In an embodiment of the present invention, according to ASTM D3417, the glass transition temperature of polylactide homopolymer or copolymer is between about 40 ℃ and about 70 ℃, preferably between about 45 ℃ and about 65 ℃, and most preferably between about 50 ℃ and about 60 ℃. In an embodiment of the present invention, the melt index of the polylactide homopolymer or copolymer is at least about 50 g / 10 min at 210°C using a 2.16 kg weight, preferably at least about 55 g / 10 min at 210°C using a 2.16 kg weight, and most preferably at least about 60 g / 10 min at 210°C using a 2.16 kg weight; and it has at most a melt index of at most about 500 g / 10 min at 210°C using a 2.16 kg weight, preferably at most about 200 g / 10 min at 210°C using a 2.16 kg weight, more preferably at most about 150 g / 10 min at 210°C using a 2.16 kg weight, and most preferably at most about 100 g / 10 min at 210°C using a 2.16 kg weight, all according to ASTM method D1238. In all instances herein, when multiple values ​​are provided for the lower limit and multiple values ​​are provided for the upper limit of any property or concentration range, the invention contemplates any range extending from and including any lower limit to and including any upper limit.

[0028] An exemplary polylactide homopolymer or copolymer is the Vercet series of resins, particularly Vercet A1000, which is commercially available from Nature Works LLC. This is a thermoplastic resin derived from an annually renewable resource, obtained in pellet form, and is an amorphous, low melting point, high flow resin.

[0029] The hot melt adhesive composition further comprises a sulfonated copolyester. In an embodiment of the present invention, the specific gravity of the sulfonated copolyester is between about 1 and about 1.5 g / cm 3 Between, preferably between about 1.1 and about 1.3 g / cm 3 Between about 1.2 and about 1.3 g / cm 3In an embodiment of the present invention, the glass transition temperature of the sulfonated copolyester is between about 30°C and about 70°C, preferably between about 35°C and about 60°C, and most preferably between about 40°C and about 50°C, according to testing using DSC (according to ASTM E1356-08), wherein the inflection point, i.e., the midpoint of the bend (secondary transition) during the second thermal cycle is determined. In an embodiment of the present invention, the intrinsic viscosity of the sulfonated copolyester is between about 0.15 dl / g and about 0.45 dl / g, preferably between about 0.2 dl / g and about 0.4 dl / g, and most preferably between about 0.25 dl / g and about 0.35 dl / g, according to ASTM D5225-14. In an embodiment of the present invention, the acid value of the sulfonated copolyester is zero or at least about 0.01 mg KOH / g and preferably at least about 0.1 mg KOH / g, and up to about 10 mg KOH / g, preferably up to about 5 mg KOH / g, and most preferably up to about 3 mg KOH / g. In an embodiment of the present invention, the hydroxyl value of the sulfonated copolyester is zero or at least about 0.01 mg KOH / g and preferably at least about 0.1 mg KOH / g, and up to about 15 mg KOH / g, preferably up to about 10 mg KOH / g, and most preferably up to about 5 mg KOH / g. In an embodiment of the present invention, the sulfonated copolyester has a weight average molecular weight between about 20,000 g / mol and 80,000 g / mol, preferably between about 25,000 g / mol and 60,000 g / mol, and most preferably between about 28,000 g / mol and 42,000 g / mol. The viscosity of the polyester is preferably between 1000 cP and 100,000 cP, most preferably between 5000 and 60,000 cP at 350°F. Viscosity is measured using a #27 spindle in a Brookfield viscometer. Viscosity is generally related to molecular weight, with higher viscosities corresponding to higher molecular weights.

[0030] According to an embodiment of the present invention, the sulfonated copolyester may be selected from those described in U.S. Pat. No. 6,410,627, which is incorporated herein by reference. The patent describes a polycondensate comprising a reaction product of:

[0031] a. at least one difunctional dicarboxylic acid or the corresponding methyl ester which is not a sulfonic monomer;

[0032] b. 2 to 25 mole percent of at least one sulfonic monomer comprising at least one metal sulfonate group or nitrogen-containing non-metal sulfonate group attached to an aromatic or alicyclic core and at least one functional group selected from the group consisting of: hydroxyl, carboxyl, and amino;

[0033] c. at least one difunctional reactant selected from a diol or a mixture of a diol and a diamine having two -NRH groups, wherein the diol contains two -C(R1)2-OH groups, wherein 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;

[0034] 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 —NRH group, an aminoalcohol having one —C(R)2—OH group and one —NRH group, or a mixture of said difunctional reactants, wherein R in the reactant is hydrogen or an alkyl group of 1 to 6 carbon atoms; and

[0035] e. 0 to 40 mole percent of a multifunctional reactant containing at least three functional groups selected from hydroxyl, carboxyl, and mixtures thereof, wherein at least a portion of the multifunctional reactant contains at least three hydroxyl groups,

[0036] wherein all stated mole percentages are based on the sum of all acid-, hydroxyl- and amino-containing reactants (equal to 200 mole percent), and wherein the polymer comprises a ratio of reactants containing acid groups (100 mole percent acid) to reactants containing hydroxyl and amino groups (100 mole percent base) such that the value of (equivalent) EQ(base) divided by (equivalent) EQ(acid) is between 0.5 and 2. The polyester composition used as a component of the hot melt adhesive of the present invention preferably comprises 60 to 100 mole percent of (a), 4 to 20 mole percent of (b), 80 to 100 mole percent of (c), 0 to 10 mole percent of (d) and 0 to 20 mole percent of (e). In other more preferred embodiments of the present invention, the polyester comprises 60 to 100 mole percent of 1,4-cyclohexanedicarboxylic acid; 4 to 20 mole percent of 5-sodiosulfoisophthalic acid or 5-sodiosulfoisophthalic acid dimethyl ester; and 80 to 100 mole percent of diethylene glycol, neopentyl glycol or cyclohexanedimethanol.

[0037] According to an embodiment of the present invention, the sulfonated copolyester may be selected from those described in U.S. Pat. Nos. 4,910,292, 4,973,656 and 4,990,593, which are incorporated herein by reference. In yet another embodiment of the present invention, the sulfonated copolyester includes commercially available from Bostik, Inc. 1831044 copolyester polymer. Hot melt adhesives based on sulfonated copolyesters are described in U.S. Pat. No. 5,750,605, which is incorporated herein by reference. Exemplary sulfonated copolyesters also include the Eastman AQ series of solid copolyesters commercially available from Eastman Chemical.

[0038] In an embodiment of the present invention, the sulfonated copolyester is water dispersible. Water dispersibility can be measured by the ability of the resin to disperse and remain as a uniform dispersion after mixing. This characteristic can be determined by combining the product with water under heat (e.g., 95° C.) and applying shear. The resin first softens when heated (i.e., it is clear and amorphous, then becomes cloudy and soft when mixed with water). Once mixing is complete, if the product does not settle or phase separate under gravity, it is said to be water dispersible.

[0039] The use of sulfonated copolyesters provides the additional advantage of providing a degree of water sensitivity that is dependent upon the ionic strength of the aqueous environment. Thus, adhesives can be formulated that are sufficiently resistant to the ionic environments encountered during use (e.g., exposure to body fluids encountered in diapers and feminine hygiene napkins), but are still able to disperse and / or debond in tap water of lower ionic strength. Thus, these adhesives are particularly useful in the construction of compostable articles.

[0040] The hot melt adhesive composition also includes a plasticizer. Preferably, the plasticizer is a solid plasticizer, which is particularly useful in embodiments requiring high heat resistance. The solid plasticizer may include a benzoate. The benzoate may be selected from the group consisting of glyceryl tribenzoate, sucrose benzoate, pentaerythritol tetrabenzoate and 1,4-cyclohexanedimethanol dibenzoate. Most preferably, the benzoate includes, consists essentially of or consists of 1,4-cyclohexanedimethanol dibenzoate, which is commercially available from Eastman Chemical Company under the trademark Benzoflex 352. One of the drawbacks of using polylactide homopolymers or copolymers is poor heat resistance. It has been found that incorporating a solid plasticizer into a formulation provides the heat resistance required for use as an adhesive for disposable cups for hot beverages. Plant wax-based solid plasticizers may also be suitable.

[0041] In one embodiment, the solid plasticizer has a melting point between about 80°C and about 160°C, preferably between about 90°C and about 150°C, more preferably between about 100°C and about 140°C, still more preferably between about 110°C and about 130°C, and most preferably between about 110°C and about 125°C using DSC according to ASTM D7138. In an embodiment of the present invention, the acid value of the solid plasticizer is zero or at least about 0.001 mg KOH / g and preferably at least about 0.01 mg KOH / g, and at most about 3 mg KOH / g, preferably at most about 1 mg KOH / g, and most preferably at most about 0.2 mg KOH / g. In an embodiment of the present invention, the hydroxyl value of the sulfonated copolyester is zero or at least about 0.01 mg KOH / g and 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.

[0042] In an embodiment 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 with relatively low viscosity (such as PEG 400) is used to reduce the viscosity of the adhesive. In embodiments where a solid plasticizer is used as the first plasticizer and the viscosity of the formulation needs to be reduced, a liquid plasticizer is particularly advantageous. Depending on the desired formulation viscosity, a range of polyethylene glycols can be used.

[0043] Other plasticizers suitable for hot melt adhesive compositions are described in U.S. Patent No. 5,753,724, which is incorporated herein by reference. Plasticizers can improve the melting characteristics of adhesives, can impart pressure-sensitive properties, can expand adhesives to reduce costs, and can increase the flexibility and melting characteristics of hot melt adhesives. Preferred plasticizers used with the hot melt adhesive of the present invention are biodegradable / compostable plasticizers. Such plasticizers typically include natural cycle oils or synthetic materials made containing ester groups or urea carbamoyl groups or amide groups. Plasticizers typically have molecular weights different from other components of the adhesive composition. When using a solid plasticizer as the first plasticizer and needing to reduce the viscosity of the formulation, a liquid plasticizer is used, such as a material with a molecular weight less than about 5,000 g / mol, preferably less than 1,000 g / mol, which can provide plasticizer properties for the composition of the present invention. Preferred types of plasticizer materials for the present invention include natural oils and fats compatible with other components disclosed herein. Another preferred class of plasticizers for use in the adhesives of the present invention includes ester plasticizers, which are typically prepared by reacting aromatic or aliphatic small molecule mono-, di- or triols with aromatic or aliphatic acid compositions. Specific examples of additional plasticizers include castor oil, TegMer 809-PEG 400 di-2-ethylhexanoate, Plasthall DBS-dibutyl sebacate, Plasthall 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 below about 25°C, ethylene glycol dibenzoate, propylene glycol dibenzoate, diethylene glycol dibenzoate, and dipropylene glycol dibenzoate.

[0044] In an embodiment of the present invention, the adhesive further comprises a stabilizer or antioxidant. Stabilizers / antioxidants useful in the hot melt adhesive compositions of the present invention are incorporated to help protect the other ingredients noted above and thus the overall adhesive system from thermal and oxidative degradation, which typically occurs during the manufacture and application of the adhesive and during ordinary exposure of the final product to the surrounding environment. The antioxidant may include hindered phenols. The hindered phenol may be selected from the group consisting of: 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; pentaerythritol tetra-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-butylphenol); 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)-ethyl 3,5-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 also contain an effective amount, preferably from about 0.1% to about 5% by weight, of a stabilizer and / or antioxidant. Preferably, from about 0.1% to 2% of a stabilizer or antioxidant is incorporated into the composition. Among the applicable stabilizers are hindered phenols and multifunctional phenols, such as sulfur- and phosphorus-containing phenols.

[0045] Polyolefin nucleating agents may also be present in the adhesive of the present invention. Nucleating agents suitable for the present invention are generally nucleating agents of a subclass called clarifiers, which are generally used in polyolefin additive packages to promote rapid crystallization. Suitable materials include dibenzylidene sorbitol derivatives, such as Millad 3988 and Millad NX8000 supplied by Milliken and Irgaclear D produced by BASF. Other suitable agents include aromatic amide systems, such as NJ Star NU-100 provided by New Japan Chemical Company. If included, nucleating agents are generally present in the adhesive composition in an amount of about 0.05% to 5% by weight of the composition, 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 also be used. For example, blends of nucleating agents and second nucleating agents different from the first nucleating agent may also be used. If desired, from about 0.05% to about 5% by weight of one or more additional nucleating agents can be blended with the first nucleating agent. The nucleating agent can be used directly as a powder, or as a slurry in a portion of a suitable plasticizer, or as a component in a masterbatch of a suitable polymer masterbatch (such as Milliken NX-10). Nucleation packages, such as those described in US2015 / 0299526, can also be included to customize the setting rate and bonding properties of the hot melt adhesive.

[0046] It should be understood that other optional additives can be incorporated into adhesive compositions of the present invention to change specific physical properties. These can include for example such materials as ultraviolet (UV) absorbers, waxes, surfactants, inert colorants, titanium dioxide, fluorescent agents and fillers. Typical fillers include talcum, calcium carbonate, clay silica, mica, wollastonite, feldspar, aluminum silicate, aluminum oxide, hydrated aluminum oxide, glass microspheres, ceramic microspheres, thermoplastic microspheres, barite and wood powder and can be up to 40% by weight and preferably included in an amount between 1% and 30% by weight.

[0047] The adhesives of the present invention are compostable. As used herein, the term "compostable" as applied to an adhesive is an adhesive that meets the following requirements: (1) Decomposition Test (using ISO 20200) as defined by ASTM D 6400-12 (84 days composting exposure) or (2) Aerobic Biodegradation (using ASTM 5338-15) as defined by ASTM D 6400-12 (141 days at 58 ± 2 ° C.). In other words, the adhesive will achieve a minimum of 90% weight loss in 84 days under the Decomposition Test conditions, or will achieve at least 90% carbon conversion (based on CO ) in 141 days according to the aerobic biodegradation test described in more detail in the Examples. 2 In a preferred embodiment, the adhesive meets both of the following requirements: (1) decomposition testing as defined by ASTM D6400-12 (using ISO 20200) (84 days composting exposure) and (2) aerobic biodegradation as defined by ASTM D 6400-12 (using ASTM 5338-15) (141 days at 58±2°C).

[0048] It has been found that the relative amounts of the various ingredients are important for the adhesive to achieve the various properties required for the desired application. It has been found that this is particularly true when the adhesive is used to seal two walls together in a beverage cup, which requires heat resistance, tolerance over a wide temperature range, and compostability. In an embodiment, the polylactic acid, the sulfonated copolyester, and the plasticizer are present in an amount effective to achieve at least 80%, preferably at least 90%, and most preferably 100% bonding performance. As used herein, "bonding performance" refers to the performance of the adhesive when applied to uncoated paperboard and tested as follows: corrugated flaps are cut into 1.5" x 4" specimens. The adhesive was applied at 350°F in a 3 / 8" bead with an open time of 2 seconds and a compression time of 2 seconds. The bonds were allowed to stand overnight at room temperature. Three bonds made with each adhesive were placed in a 0°F refrigerator and a 160°F oven for 24 hours. At that time, the bonds were tested for fiber tear percentage immediately after removal. "Fiber tear" refers to areas where the substrate is torn, as opposed to areas where the adhesive fails, either adhesively or cohesively. In preferred embodiments, the polylactic acid, the sulfonated copolyester, and the solid plasticizer are present in effective amounts to achieve the above-mentioned bonding properties at a temperature of about 175°F, most preferably in a temperature range from 0°F to 175°F. In other embodiments, the polylactic acid and the sulfonated copolyester are present in a weight ratio of between about 1:1 and about 9:5 by weight, preferably between about 6:5 and about 8:5 by weight, and most preferably between about 13:10 and about 3:2 by weight.

[0049] According to an embodiment of the present invention, the formulation comprises the following ingredients in approximately the following weight percentages:

[0050] Polylactic acid is present in an amount to serve as a base polymer to provide cohesion to the adhesive, and in embodiments is present in an amount between about 25% and about 43% by weight, preferably between about 30% and about 38% by weight, and most preferably between about 31% and about 37% by weight;

[0051] The sulfonated copolyester is present in an amount effective to act as an adhesion promoter to porous substrates such as paperboard or labels, and in embodiments is present in an amount between about 15% and about 35% by weight, preferably between about 20% and about 30% by weight, and most preferably between about 22% and about 28% by weight;

[0052] A plasticizer is present in an amount effective to increase the heat resistance of the formulation to a desired level (e.g., to the above-mentioned bonding properties at elevated temperatures), and in embodiments is present in an amount between about 5% and about 60% by weight, preferably between about 15% and about 55% by weight, more preferably between about 20% and about 50% by weight, and most preferably between about 36% and about 42% by weight; and

[0053] ●If used, the second plasticizer is present in an amount effective to reduce the viscosity of the adhesive to the desired value, and in embodiments is present in an amount between about 1% and 5% by weight, preferably between about 1.3% and about 3% by weight, and most preferably between about 1.5% and about 2% by weight.

[0054] ●If used, an antioxidant (such as a hindered phenol) is present in an amount effective to prevent oxidation or stabilize the adhesive, and in embodiments is present in an amount between about 0.1% and about 1% by weight, preferably between about 0.25% and about 0.75% by weight, and most preferably between about 0.4% and about 0.6% by weight.

[0055] Preferably, the composition comprises no more than 5 wt%, more preferably no more than about 4 wt%, and most preferably no more than about 3 wt% of an ingredient having a hydroxyl value greater than 100 mg KOH / g. Such an ingredient may be, for example, styrene allyl copolymer, neopentyl glycol phthalate, polyester polyol, or a combination thereof, as disclosed in U.S. Pat. No. 6,410,627, which is incorporated herein by reference.

[0056] There is no particular order to making the adhesive composition of the present invention, and it can be made using conventional process steps.The adhesive can be made by mixing the various ingredients and then heating just before applying to a substrate.

[0057] The viscosity of adhesive material according to the present invention should be suitable for processing and applied to its substrate as the viscosity at the application temperature of hot melt adhesive. The adhesive with relatively low viscosity at low application temperature needs to be processed by standard hot melt adhesive equipment and obtains the desired pattern and therefore the suitable bonding performance at the application temperature. Usually, according to ASTM D3236, the viscosity is equal to or less than about 50,000cP at the application temperature, preferably equal to or less than about 40,000cP at the application temperature, even more preferably less than about 35,000cP at the application temperature, and more preferably less than about 30,000cP at the application temperature. All viscosities determined herein are measured according to the ASTM standard of this modification. Preferably, at the application temperature, the viscosity of the composition is at least 1,000cP, more preferably at least 5,000cP, more preferably at least about 7,500cP, and most preferably at least about 15,000cP. Thus, at 121°C, the viscosity may be between 1,000 cP and 35,000 cP and between 5,000 cP and 20,000 cP. In other embodiments, the viscosity of the composition at various typically used application temperatures is between any range contemplated herein, the value of the application temperature depending on the specific application of the adhesive, between 121°C and 180°C, such as at 121°C, 127°C, 135°C, 149°C, and 177°C. In embodiments where the adhesive is used to bond double-walled cups for hot beverages, the viscosity of the adhesive at 177°C is preferably between about 5,000 cP and about 50,000 cP, more preferably between about 15,000 cP and about 35,000 cP, and most preferably between about 20,000 cP and about 30,000 cP.

[0058] The end-use application requirements 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 and ball softening point of the adhesive as determined by ASTM E28-99 may be between about 180°F and about 300°F, more preferably between about 200°F and about 280°F, and most preferably between about 220°F and about 260°F.

[0059] Various coating techniques can be used to apply hot melt adhesive to one or more substrates.Example includes hot melt slot die (slot die) coating, hot melt wheel coating, hot melt roller coating, melt spray coating and slot type spray coating, spiral spray coating and packaging spray coating method as the method for fixing elastic strand.Spraying technology is numerous, and can be carried out with or without the assistance of compressed air, and this compressed air will shape the adhesive spray pattern.Hot melt adhesive material is usually melted and pumped to the final coating point on substrate by hose.

[0060] In an embodiment of the present invention, a method for forming a double-walled container comprises the following steps:

[0061] (a) applying a hot melt adhesive composition described herein in a molten state to an outer surface of a first generally cylindrical paperboard substrate;

[0062] (b) joining a second generally rectangular paperboard substrate to the first paperboard substrate, wherein the second paperboard substrate is longer in circumference than the first paperboard substrate, thereby providing an axial strip of the second paperboard substrate with overlapping ends; and

[0063] (c) applying the hot melt adhesive composition in a molten state to one of the mating surfaces of the axial strips; and

[0064] (d) joining the joined surfaces of the axial strips to provide the double-walled container.

[0065] In an embodiment of the present invention, step (a) comprises applying the hot melt adhesive in a radial pattern. In other embodiments, steps (a) and (c) comprise applying the hot melt adhesive composition in the form of beads. Preferably, the paperboard is compostable. Still more preferably, the paperboard for the container is compostable and the container is a beverage cup. One such double-walled container is described in U.S. Patent No. 6,109,518, which is incorporated herein by reference.

[0066] Compostable hot melt adhesive of the present invention can be used in multiple applications, especially wherein wish to include adhesive final product is compostable application.As discussed above, the embodiment of adhesive of the present invention is particularly suitable for double wall paperboard beverage cup.Exemplary other applications relate to box and carton application, are used for tree bulb or plant seed together with burlap or other compostable substrates, and are used together with other compostable films.In each of these, the adhesive in molten state is applied to the first substrate, then the second substrate (or a part of the first substrate) is contacted with the adhesive, then it is cooled and thereby the first substrate is bonded to the second substrate (or the other parts of the first substrate folded onto the first substrate and spliced ​​with it).For example, in one embodiment, tree bulb or plant seed can be wrapped in compostable burlap, adhesive can be applied to the splicing area of ​​burlap, and then the burlap is folded onto itself, so that the two splicing surfaces of burlap are bonded to each other when the hot melt adhesive cools. In another embodiment, a first compostable film or substrate is contacted with the adhesive of the present invention and then a second compostable film is contacted with the adhesive and allowed to cool, thereby bonding the two compostable films together to form a compostable laminate.

[0067] Invention

[0068] Aspect 1. A hot melt adhesive composition comprising:

[0069] (a) polylactide homopolymer or copolymer;

[0070] (b) sulfonated copolyesters; and

[0071] (c) plasticizers,

[0072] The binder is compostable.

[0073] Aspect 2. The composition according to aspect 1, wherein the polylactide homopolymer or copolymer is selected from the group consisting of: polylactic acid; and copolymers of lactones, preferably glycolide and caprolactone.

[0074] Aspect 3. The composition of Aspect 1, wherein the polylactide homopolymer or copolymer comprises, consists essentially of, or consists of polylactic acid.

[0075] Aspect 4. The composition of any of aspects 1-3, wherein the polylactic acid, the sulfonated copolyester, and the plasticizer are present in an amount effective to achieve at least 80%, preferably at least 90%, and most preferably 100% of the bonding performance.

[0076] Aspect 5. The composition of aspect 4, wherein the polylactic acid, the sulfonated copolyester and the solid plasticizer are present in an amount effective to achieve the bonding properties at a temperature of about 175°F, most preferably in a temperature range of from 0°F to 175°F.

[0077] Aspect 6. The composition of any of Aspects 1-5, wherein the polylactide homopolymer or copolymer and the sulfonated copolyester are present in a weight ratio between about 1:1 and about 9:5 by weight, preferably between about 6:5 and about 8:5 by weight, and most preferably between about 13:10 and about 3:2 by weight.

[0078] Aspect 7. The composition according to any one of aspects 1 to 6, wherein:

[0079] (a) the polylactide homopolymer or copolymer is present in an amount between about 25% and about 43% by weight, preferably between about 30% and about 38% by weight, and most preferably between about 31% and about 37% by weight;

[0080] (b) the sulfonated copolyester is present in an amount between about 15% and about 35% by weight, preferably between about 20% and about 30% by weight, and most preferably between about 22% and about 28% by weight; and

[0081] (c) the plasticizer is present in an amount between about 5% and about 60% by weight, preferably between about 15% and about 55% by weight, more preferably between about 20% and about 50% by weight, and most preferably between about 36% and about 42% by weight.

[0082] Aspect 8. The composition of any of aspects 1-7, wherein the sulfonated copolyester is water dispersible.

[0083] Aspect 9. The composition of any one of aspects 1-8, wherein the plasticizer comprises a solid plasticizer.

[0084] Aspect 10. The composition of aspect 9, wherein the solid plasticizer comprises a benzoate.

[0085] Aspect 11. The composition according to aspect 10, wherein the benzoate is selected from the group consisting of glyceryl tribenzoate, sucrose benzoate, pentaerythritol tetrabenzoate and 1,4-cyclohexanedimethanol dibenzoate.

[0086] Aspect 12. The composition of aspect 10, wherein the benzoate comprises, consists essentially of, or consists of 1,4-cyclohexanedimethanol dibenzoate.

[0087] Aspect 13. The composition of any of aspects 1-12, further comprising a second plasticizer.

[0088] Aspect 14. The composition of aspect 13, wherein the second plasticizer is selected from the group consisting of ethylene glycol, propylene glycol, and polyethylene glycol.

[0089] Aspect 15. The composition of Aspect 13 or 14, wherein the second plasticizer is present in an amount between about 1% and 5% by weight, preferably between about 1.3% and about 3% by weight, and most preferably between about 1.5% and about 2% by weight.

[0090] Aspect 16. The composition of any one of aspects 1-15, further comprising an antioxidant.

[0091] Aspect 17. The composition of aspect 16, wherein the antioxidant comprises, consists essentially of, or consists of a hindered phenol.

[0092] Aspect 18. The composition of aspect 17, wherein 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)-ethyl 3,5-di-tert-butyl-4-hydroxybenzoate; and sorbitol hexa[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0093] Aspect 19. A composition as described in any of Aspects 16-18, wherein the antioxidant is present in an amount between about 0.1% and about 1% by weight, preferably between about 0.25% and about 0.75% by weight, and most preferably between about 0.4% and about 0.6% by weight.

[0094] Aspect 20. The composition of any of aspects 1-19, wherein the composition comprises no greater than 5 wt%, more preferably no greater than 4 wt%, and most preferably no greater than 3 wt% of a component having a hydroxyl value greater than 100 mg KOH / g.

[0095] Aspect 21. The composition of any of Aspects 1-20, wherein the sulfonated copolyester has a weight average molecular weight between about 20,000 g / mol and 80,000 g / mol, preferably between about 25,000 g / mol and 60,000 g / mol, and most preferably between about 28,000 g / mol and 42,000 g / mol.

[0096] Aspect 22. The composition of any of Aspects 1-21, wherein the polylactide homopolymer or copolymer has a melt index of at least 50, preferably at least 55, and most preferably at least 60 g / 10 min at 210° C. using a 2.16 kg weight according to ASTM method D1238.

[0097] Aspect 23. The composition of any of Aspects 1-22, wherein the binder meets both of the following requirements: (1) decomposition testing 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).

[0098] Aspect 24. The composition of any of Aspects 1-23, wherein the adhesive has a ring and ball softening point as determined by ASTM E28-99 between about 180°F and about 300°F, more preferably between about 200°F and about 280°F, and most preferably between about 220°F and about 260°F.

[0099] Aspect 25. A method for forming a double-walled container, the method comprising the steps of:

[0100] (a) applying a hot melt adhesive composition according to any one of aspects 1 to 24 in a molten state to an outer surface of a first generally cylindrical paperboard substrate;

[0101] (b) joining a second generally rectangular paperboard substrate to the first paperboard substrate, wherein the second paperboard substrate is longer in circumference than the first paperboard substrate, thereby providing an axial strip of the second paperboard substrate with overlapping ends; and

[0102] (c) applying the hot melt adhesive composition in a molten state to one of the mating surfaces of the axial strips; and

[0103] (d) joining the joined surfaces of the axial strips to provide the double-walled container.

[0104] Aspect 26. The method of aspect 25, wherein step (a) comprises applying the hot melt adhesive in a radial pattern.

[0105] Aspect 27. The method of aspect 25 or 26, wherein steps (a) and (c) comprise applying the hot melt adhesive composition in the form of beads.

[0106] Aspect 28. The method of any one of aspects 25-27, wherein the paperboard is compostable.

[0107] Aspect 29. A container formed by the method of any one of aspects 25-28.

[0108] Aspect 30. The container of aspect 29, wherein the paperboard used for the container is compostable and the container is a beverage cup.

[0109] Examples

[0110] The following examples illustrate several aspects of certain preferred embodiments of the present invention and should not be construed as limiting the present invention.

[0111] The feasibility of using the adhesive according to the present invention for double-walled beverage cups was investigated. Specifically, the bonding properties of three formulations were tested according to the following criteria.

[0112] The adhesive ingredients shown in Table 1 below were mixed at room temperature and then heated. The molten adhesive was heated to 350°F and then applied to the outer, uncoated paperboard wall of the cup in radial beads. The outer wall of a commercially available paperboard cup was adhered to the inner wall by splicing the outer wall with the adhesive just applied to the inner wall. At a portion of the second wall where it overlaps itself, another radial bead was applied to one of the spliced ​​surfaces of the second wall to produce an axial strip. The second wall was then adhered to itself by splicing the spliced ​​surfaces of the axial strip. The radial beads (adhesive around the inner wall of the cup) create a gap between the inner wall and the outer wall to provide thermal insulation. The adhesive was applied at 350°F using conventional adhesive application equipment.

[0113] The adhesive bond strength is measured by peeling off the end seal to check for 100% fiber tear (i.e., only the wall itself tears and the adhesive has not failed), and heat resistance is tested by pouring hot water into a cup immediately after applying the adhesive for 1 minute. The end seal must have no delamination from the top to the bottom seal to pass the test. The adhesive bond strength at 0°F and boiling water conditions is compared to current conventional hot melt adhesives shown as a control.

[0114] As shown in Table 1, the ingredients used were polylactic acid ("PLA") sold by Nightwalk LLC under the trademark Vercet A1000; 1831044 (“sulfonated copolyester”); a solid plasticizer sold under the trademark Benzoflex 352 by Eastman Chemical (“solid plasticizer”); a sulfonated copolyester sold under the trademark Carbowax Sentry by Dow Chemical (“sulfonated copolyester”); PEG400 liquid plasticizer sold; and conventional antioxidant ("AO"). Table 1 lists the weights (in grams) of the various ingredients. As shown, Formulation 1 has about 30 wt% solid plasticizer. Formulation 1 did not pass the hot water test desired for this application. Formulation 2 (which has more solid plasticizer than Formulation 1, but no liquid plasticizer) also had very good adhesion just off-line and passed the hot water test compared to Formulation 1. However, after 10 minutes at room temperature, the adhesive became brittle and failed in both radial and end seal applications. Formulation 3 passed both off-line and aging (1 day, 5 days, and 2 months at different temperatures of 0°F, 40°F, 72°F, 140°F, 160°F) adhesive bond strength tests.

[0115] In addition, Mix 3 unexpectedly exhibited broader performance in use temperature (0°F-160°F) and boiling water conditions (microwave 3.0 minutes, about 210°F water temperature). Although Formulations 1 and 2 do 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 binder.

[0116] Table 1

[0117]

[0118] An analysis was performed to determine whether the adhesive composition of Formulation 3 met the requirements of the decomposition test as defined by ASTM D 6400-12 (using ISO 20200). Specifically, a drawn down film of this adhesive with a maximum thickness of 31.5 mg was evaluated at 58±2°C for up to 84 days using ISO 20200 according to ASTM D 6400-12. The compost material tested had a carbon-nitrogen ratio of 30:1, which is within the specifications of this test. At the beginning of the test, the pH of the compost material was approximately 7.0, and the total dry solids content was 44.5% when dried to constant weight at 105°C. The mature mushroom compost used in the test was purchased from Monterey Mushrooms in Princeton, Illinois, and had a C:N ratio of 13:1 as received. In order to meet this requirement, the sample tested must achieve a minimum weight loss of 90% within 84 days of the test. After 84 days, the adhesive sample tested had completely decomposed (100% weight loss).

[0119] Analysis was performed to determine whether the adhesive composition of Formulation 3 met the requirements for aerobic biodegradation as defined by ASTM 5338-15. Specifically, ASTM D 6400-12 mineralization of adhesive samples exposed to aerobic biodegradation (tier two level testing) at 58±2°C using ASTM D-5338-15 mineralization by contact with a composting medium was evaluated. The laboratory raw compost tested had a C:N ratio of 29:1, which is within the specifications for this test. At the beginning of the test, the pH of the compost material was approximately 7.0, and the total dry solids content was 50.0% when dried to constant weight at 105°C. The mature mushroom compost used in the test was purchased from Monterey Mushrooms, Princeton, Illinois, and had a C:N ratio of 14:1 as received. To meet this requirement, the tested samples must achieve a minimum carbon conversion of 70% within forty-five (45) days when mineralized according to ASTM D 5338-15 and a carbon conversion of 90% within one hundred forty-one (141) days when mineralized according to ASTM D 5338-15. The tested binder samples met both requirements, including achieving an average carbon conversion of 91.83% within 141 days.

[0120] Where a range of values ​​is provided, it is to be understood that each intervening value between the upper and lower limits of such range and any other stated or intervening value in the stated range, and any combination or subcombination of intervening values, is included within the recited values. In addition, the invention includes ranges of components that are the lower limit of a first range and the upper limit of a second range for such components.

[0121] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. All publications and patents specifically mentioned herein are incorporated by reference in their entirety for all purposes, including describing and disclosing chemicals, instruments, statistical analyses and methods reported in the publications that may be used in connection with the present invention. Nothing herein should be construed as an admission that the present invention is not entitled to be antedated by virtue of prior invention such disclosures.

[0122] Although illustrated and described herein with reference to certain specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the range of equivalents of the claims and without departing from the spirit of the invention.

Claims

1. A hot melt adhesive composition comprising: (a) polylactide homopolymer or copolymer; (b) sulfonated copolyesters; and (c) plasticizers, The binder is compostable.

2. The composition according to claim 1, in, The polylactide homopolymer or copolymer is selected from the group consisting of: polylactic acid; and copolymers of lactones, preferably glycolide and caprolactone.

3. The composition according to claim 1, in, The polylactide homopolymer or copolymer includes polylactic acid.

4. The composition according to claim 3, in, The polylactic acid, the sulfonated copolyester, and the plasticizer are present in amounts effective to achieve at least 80%, preferably at least 90%, and most preferably 100% of the bonding performance.

5. The composition according to claim 4, in, The polylactic acid, the sulfonated copolyester and the solid plasticizer are present in amounts effective to achieve the bonding properties at a temperature of about 175°F, most preferably within a temperature range of from 0°F to 175°F.

6. The composition of claim 3, in, The polylactic acid and the sulfonated copolyester are present in a weight ratio of between about 1:1 and about 9:5 by weight, preferably between about 6:5 and about 8:5 by weight, and most preferably between about 13:10 and about 3:2 by weight.

7. The composition of claim 3, in: (a) the polylactic acid is present in an amount between about 25% and about 43% by weight, preferably between about 30% and about 38% by weight, and most preferably between about 31% and about 37% by weight; (b) the sulfonated copolyester is present in an amount between about 15% and about 35% by weight, preferably between about 20% and about 30% by weight, and most preferably between about 22% and about 28% by weight; and (c) the plasticizer is present in an amount between about 5% and about 60% by weight, preferably between about 15% and about 55% by weight, more preferably between about 20% and about 50% by weight, and most preferably between about 36% and about 42% by weight.

8. The composition of claim 1, in, The sulfonated copolyesters are water dispersible.

9. The composition of claim 1, in, The plasticizer includes a solid plasticizer.

10. The composition of claim 9, in, The solid plasticizer includes benzoate esters.

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