Compostable adhesive composition and laminate

Abstract

The present disclosure provides a composition. In an embodiment, an adhesive composition is provided. The adhesive composition includes a reaction product composed of (A) a polyester polyol component comprising (i) a dicaboxylic acid, (ii) a CB-CS diol, (iii) a glycol; and (B) an aliphatic isocyanate. The present disclosure also provides a laminate with a first substrate and a second substrate and the present adhesive composition located between the first substrate and the second substrate.

Description

COMPOSTABLE ADHESIVE COMPOSITION AND LAMINATEBACKGROUND

[0001] Adhesives are ubiquitous in the packaging art. Adhesives adjoin different functional layers together in order to meet packaging requirements such as heat sealability, attractive appearance, and suitable barrier properties. Adhesives also need to meet processability requirements such as fast cure, good heat resistance, adequate chemical resistance, and compliance with governmental food regulations. Polyurethane-based adhesives are a common material used in packaging applications.

[0002] Sustainability is growing in significance in the packaging industry. It is known that packaging materials made from non-compostable and / or non-biodegradable plastic films negatively impact landfill sites. As consumers become more environmentally conscious, suppliers and converters have made progress in developing recyclable and biodegradable substrates for packaging in order to reduce the negative environmental concerns resulting from conventional flexible packaging.

[0003] Hence, the art recognizes the need to develop adhesive compositions that have the necessary functionality (processability, adhesion performance, etc.) and yet will readily degrade and / or readily decompose when subject to stimulation from a bioactive environment. A need further exists for polyurethane-based adhesive compositions for packaging that are compostable.SUMMARY

[0004] The present disclosure provides a composition. In an embodiment, an adhesive composition is provided. The adhesive composition includes a reaction product composed of (A) a polyester polyol component comprising (i) a dicaboxylic acid, (ii) a C3-C6 diol, (iii) a glycol; and (B) an aliphatic isocyanate.

[0005] The present disclosure also provides a laminate. In an embodiment, a laminate is provided and includes a first substrate and a second substrate. The the present adhesive composition is located between the first substrate and the second substrate. The adhesivecomposition located between the first substrate and the second substrate includes a reaction product composed of (A) a polyester polyol component comprising (i) a dicaboxylic acid, (ii) a Cs-Ce diol, (iii) a glycol; and (B) an aliphatic isocyanate.DEFINITIONS

[0006] Any reference to the Periodic Table of Elements is that as published by CRC Press, Inc., 1990-1991. Reference to a group of elements in this table is by the new notation for numbering groups.

[0007] For purposes of United States patent practice, the contents of any referenced patent, patent application or publication are incorporated by reference in their entirety (or its equivalent US version is so incorporated by reference) especially with respect to the disclosure of definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure) and general knowledge in the art.

[0008] The numerical ranges disclosed herein include all values from, and including, the lower and upper value. For ranges containing explicit values (e.g., a range from 1, or 2, or 3 to 5, or 6, or 7), any subrange between any two explicit values is included (e.g., the range 1-7 above includes subranges 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6; etc.).

[0009] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight and all test methods are current as of the filing date of this disclosure.

[0010] "Bio-based" or "bio-based material" refers to a material derived from plants and / or other naturally occurring agricultural, marine, and forestry materials. The benefit of a bio-based material resides its origin and is recognized by the industry. The term "bio-based" refers to a raw material, which is at least partially derived, or wholly derived, from natural and / or renewable sources. A bio-based material excludes a petroleum-based material. The term "bio-based material" does not refer to the production process of the material, but only to the source from which the bio-based material is derived.

[0011] "Biomass" as used herein means organic material.

[0012] The term "composition" refers to a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of thecomposition.

[0013] The terms "comprising," "including," "having," and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any succeeding recitation any other component, step, or procedure, excepting those that are not essential to operability. The term "consisting of" excludes any component, step, or procedure not specifically delineated or listed. The term "or," unless stated otherwise, refers to the listed members individually as well as in any combination. Use of the singular includes use of the plural and vice versa.

[0014] A "dicarboxylic acid" is a compound containing two carboxyl (— COOH) groups.

[0015] A "glycol," as used herein, is a compound with at least two hydroxyl (--OH) groups attached to respective two different carbon atoms. By way of example, the simplest glycol is ethylene glycol, with structure HO-CH2-CH2-OH.

[0016] An "isocyanate" is a chemical that contains at least one isocyanate group in its structure. An isocyanate group is represented by the formula: — N=C=O. An isocyanate that contains more than one, or at least two, isocyanate groups is a "polyisocyanate." An isocyanate that has two isocyanate groups is a di-isocyanate and an isocyanate that has three isocyanate groups is a triisocyanate, etc. An isocyanate may be aromatic or aliphatic.

[0017] A "polyether" is a compound containing two or more ether linkages in the same linear chain of atoms.

[0018] A "polyester" is a compound containing two or more ester linkages in the same linear chain of atoms.

[0019] A "polyester polyol" is a compound that is a polyester and a polyol.

[0020] A "polymer" is a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term "homopolymer" (employed to refer to polymers prepared from only one type of monomer, with the understanding that trace amounts of impurities can be incorporated into the polymer structure), and the term "interpolymer" (which is used interchangeably with the term "copolymer") includes bipolymers(employed to refer to polymers prepared from two different types of monomers), terpolymers (employed to refer to polymers prepared from three different types of monomers), and polymers prepared from more than three different types of monomers. Trace amounts of impurities, for example, catalyst residues, may be incorporated into and / or within the polymer. It also embraces all forms of copolymer, e.g., random, block, etc. It is noted that although a polymer is often referred to as being "made of" one or more specified monomers, "based on" a specified monomer or monomer type, "containing" a specified monomer content, or the like, in this context the term "monomer" is understood to be referring to the polymerized remnant of the specified monomer and not to the unpolymerized species. In general, polymers herein are referred to as being based on "units" that are the polymerized form of a corresponding monomer.

[0021] A "polyol" is an organic compound containing multiple hydroxyl (—OH) groups. In other words, a polyol contains at least two hydroxyl groups. Nonlimiting examples suitable polyols include diols (which contain two hydroxyl groups), triols (which contain three hydroxyl groups), and multi-hydroxyl containing polyols.

[0022] A "solvent-less adhesive" is an adhesive composition that is void of, or substantially void of, a solvent.

[0023] A "solvent-based adhesive" is an adhesive composition that contains any kind of organic solvent, By way of example, the solvent can be ethylacetate, methylethylketone (MEK), etc.TEST METHODS

[0024] Acid value (or acid number) was measured in accordance with ASTM D 1386 / 7. Acid value is a measure of the amount of carboxylic acid present in a component ora composition. The acid value is the number of milligrams of potassium hydroxide required for the neutralization of free carboxylic acids present in one gram of a substance. Units for acid value are mg KOH / g.

[0025] Hydroxyl (OH) number. OH number was measured in accordance with ASTM E1899-16. OH number is a measure of the amount of hydroxyl group present in the polyols, the OH value is defined as the number of milligrams of potassium hydroxide (KOH) required to neutralize the acetic acid taken up on acetylation of one gram of a chemical substance that contains free hydroxyl groups. Units for OH number are mg KOH / g.

[0026] Boil-in-Bag test. Laminates of 8 inches (20.32 cm) x 12 inches (30.48 cm) were folded onto themselves to provide a structure that is 20.32 cm x 15.24 cm, the structure having a first side and a second side. Thus, the first side and the second side each is formed from the same laminate. The first substrate (polyethylene ("PE") film) of the first side is in contact with the first substrate (PE film) of the second side. The structure has four edges, including a fold edge and three open edges. Two of the open edges are heat sealed to form a pouch. Heat sealing occurs at 140°C for one second at a pressure of 300 N / 15 mm. Two to three pouches are made from each example.

[0027] Each pouch is filled through the remaining open edge with 180 mL of a soup (Morton soup, which is a mixture of bean oil, ketchup, and vinegar with a 1:1:1 mixing ratio). Splashing the soup onto a heat seal area is avoided to prevent heat seal failure. After filling, the open edge is heat sealed in a manner that minimizes air entrapment inside of the closed pouch. Each closed pouch has four closed edges and an interior void that is 18.82 cm x 13.74 cm (which is filled with soup). The integrity of each heat seal was visually inspected to ensure no flaws were present in the sealing that would cause the pouch to leak during testing. Pouches with suspected flaws were discarded and replaced.

[0028] A pot was filled 2 / 3 full with water, and brought to a rolling boil. The boiling pot is covered with a lid to minimize water and steam loss. The pot was observed during the test to ensure enough water is present to maintain boiling. The pouches were individually placed in the boiling water, and kept in the boiling water for 30 minutes. The pouches were then removed from the boiling water and visually inspected for tunneling, bubbling, blistering, delamination, and / or leakage.

[0029] The pouches were cut open, emptied of soup, and rinsed with soap and water. One or more strips (15 mm x 175 mm) of laminate were cut from the pouches (excluding heat seal areas). Bond strength of the laminate was measured in accordance with the 90° T-Peel Test as described above. Heat seal strength of the laminate was measured in accordance with the heat seal strength test described above. Bond strength and heat seal strength were measured as soon as possible after the pouches are emptied of soup. The interior of the pouches were visually inspected for defects

[0030] Bond Strength (180° T-Peel Test). Bond strength was measured in accordance withthe 180° hand-assisted T-Peel Test. The laminate was cut into "175 mm x 15 mm" strips (each strip had a bond area of "175 mm x 15 mm") after curing in an oven at 40°C and for two days for the initial T-peel bond strength test. Bond strength was also measured after the boil-in- bagtest after further 5days curing and after further 12days curing. An Instron 5943 peel tester was set at a 254 mm / min crosshead speed. During testing, the tail of the strip was pulled slightly by finger to make sure the tail remains oriented at 90° to the peeling direction and the pulling direction is at 180°. The average bond strength (gram per 25.4 millimeter (g / 25.4mm)) was determined from the force versus distance profile. Three samples were tested and the average "bond strength" reported.

[0031] Brookfield viscosity was measured by Brookfield viscometer DVII+ with spindle #27 at 20rpm and the given temperature.

[0032] Compostability. The terms "compostable" and "compostability" encompass factors such as biodegradability, disintegration, and ecotoxicity. The terms 'biodegradable, ''biodegradability,' and variants thereof refer to the nature of the material to be broken down by microorganisms. Biodegradable means a material breaks down through the action of a microorganism, such as a bacterium, fungus, enzyme, and / or virus over a period of time. The term "disintegration," or "disintegrate," and variants thereof refer to the extent to which the material breaks down and falls apart. Compostability refers the ability of material is biodegraded to become carbon dioxide directly. Ecotoxicity testing determines whether the material after composting shows any inhibition on plant growth or the survival of soil or other fauna. Biodegradability and compostability may be measured by visually inspecting a substrate that has been exposed to a biological inoculum (such as a bacterium, fungus, enzyme, and / or virus) to monitor for degradation. Alternatively, the biodegradable substrate passes ASTM Standard D6400; and alternatively, the biodegradable substrate passes ASTM Standard D6868-03.

[0033] FTIR (Fourier-transform infrared "FTIR" spectroscopy) spectra were obtained by scanning samples of the adhesive compositions with a Thermo Scientific™ Nicolet™ iS™5 FTIR Spectrometer with an i D7 ATR probe.

[0034] Gel permeation chromotatography (GPC). Weight average molecular weight (Mw) and number average molecular weight (Mn) of polyester polyols was measured by gelpermeation chromatography (GPC). The samples were prepared for GPC analysis by dissolving approximately 20 mg of sample in lOg of tetrahydrofuran (THF). GPC separations were carried out on a Waters Alliance HPLC system using an Agilent PLgel 5 pm particle size column (4 columns in 1 set, with pore size of 50, 100, 1000, 10000 A). Calibration was completed using polystyrene standards from Agilent Technologies, PS EasiVials, prepared in THF.Analysis Conditions:• Column temperature: 40 °C• Eluent: Tetrahydrofuran, unstabilized• Flow rate: 1.0 mL / min• Injection volume: 100 pL• Sample concentration: 2.0 mg / mL for polyol, approximately 10 mg / mL for prepolymer• Analysis time: 45 min• Detector: Waters Refractive Index detector and Waters 2489 UV / Vis Detector 254 nm

[0035] Molecular weight <1000. The percent of polymer molecular weight less than 1000 is calculated during the integration and quantification of the GPC peak. The Waters Alliance HPLC system software will determine how much of the peak falls over the range of 1000 based on the calibration curve used to do the integration. The integration is based on the retention time of the standards used for calibration and the sample peak. Results are reported in percent (%).

[0036] Molecular weight < 500. The percent of polymer molecular weight less than 500 is calculated during the integration and quantification of the peak. The software will determine how much of the peak falls over the range of 500 based on the calibration curve used to do the integration. The integration is based on the retention time of the standards used for calibration and the sample peak. Results are reported in percent (%).

[0037] Heat seal strength. Laminates were heat sealed in an HSG-C Heat-Sealing Machine, available from Brugger Company, under 160°C seal temperature and 40PSI pressure for 1 second, are then cooled to room temperature (23°C) and cut into "175 mm x 15 mm" strips (each strip had a heat seal area of "175 mm x 15 mm"). A 5940 Series Single Column Table Top System, available from Instron Corporation, set at a crosshead speed of 254 mm / min, was used to measure the heat seal strength of the strip. Three samples were tested and the average "heat seal strength" was reported in grams per 25.4 millimeter (g / 25.4mm).

[0038] Isocyanate group (NCO) content by weight was measured in accordance with ASTMD2572-97. The Isocyanate Index or ("NCO Index") is the molar ratio of isocyanate groups in the isocyanate component to the amount of hydroxyl groups in the dimer acid polyester polyol component. The NCO Index is calculated in accordance with the following Equation (1): Isocyanate Component NCO wt% / 42)x7?iix ratioNCO Index = Equation (1). (Hydroxyl Value of Polyol Component / 56106)

[0039] Particle size. The particle size analysis was performed in a Malvern Mastersizer 3000 laser diffraction particle sizer equipped with a Hydro LV liquid dispersion unit. To prepare the sample for analysis, 200 mg of the powder was pre-dispersed in 10 ml_ of 1.5 wt% Brij 35 surfactant solution (except for PVOH LM-10, which was added directly to the dispersion unit). The pre-dispersed sample was added dropwise to the dispersion unit until a 1% obscuration level was reached. A fitting Model with Rl = 1.50, Al = 0.01 was used to calculate the particle size distribution. The percentile particle sizes (Dv90) was used for comparison; the size units are in micrometers.DETAILED DESCRIPTION

[0040] The present disclosure provides an adhesive composition. In an embodiment, the adhesive composition is a reaction product of (A) a polyester polyol component and (B) an aliphatic isocyanate. The (A) polyester polyol component is a reaction product of (i) a dicarboxylic acid, (ii) an C3-C6 diol, and (iii) a glycol.A. Adhesive composition

[0041] The present adhesive composition includes (A) the polyester polyol component. The polyester polyol component is the reaction product of (i) a dicarboxylic acid, (ii) a C3-C6 diol, and (iii) a glycol.

[0042] In an embodiment, the dicarboxylic acid is an aliphatic dicarboxylic acid. Nonlimiting examples of suitable aliphatic dicarboxylic acids include C2-C20 dicarboxylic acids such ascyclohexane dicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, itaconic acid, malonic acid, suberic acid, 2-methyl succinic acid, 3,3-diethyl glutaric acid, 2,2-dimethyl succinic acid, succinic acid, and trimellitic acid, dodecane dicarboxylic acid (C12), and combinations thereof. In an embodiment, the aliphatic dicarboxylic acid is a C2-C& dicarboxylic acid, such as succinic acid.

[0043] The (A) polyester polyol component includes an C3-C6 diol. The C3-C6 diol is a saturated C3-C6 diol. Nonlimiting examples of suitable C3-C6 diol include propane-1, 3-diol, butane-1,4 diol, and combinations thereof. In an embodiment, the C3-C6 diol is butane-l,4-diol.

[0044] The (A) polyester polyol component includes a glycol. Nonlimiting examples of suitable glycol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, and combinations thereof. In an embodiment, the glycol is diethylene glycol.

[0045] In an embodiment, a catalyst is used to promote the reaction of the (i) dicarboxylic acid,(ii) the C3-C6 diol, and (iii) a glycol. Nonlimiting examples of suitable catalyst include titanium butoxide, titanium isobutoxide, titanium propoxide or other alkoxide), and combinations thereof. The condensation polymerization of (i) dicarboxylic acid, (ii) the C3-C5 diol, and (iii) the glycol was conducted under nitrogen protection starting from 150°C gradually increasing to 230°C while removing the water, and finally applying a vacuum to drive the reaction to completion.

[0046] In an embodiment, the polyester polyol component (A) is the reaction product of a reaction mixture comprising, or consisting of:(i) from 35 wt% to 65 wt%, or from 45 wt% to 55 wt% of the dicarboxylic acid, or succinic acid,(ii) from 5 wt% to 25 wt%, or from 10 wt% to 20 wt% of the C3-C6 diol, or butane-1,4- diol,(iii) from 20 wt% to 40 wt%, or from 25 wt% to 35 wt% of the glycol, or diethylene glycol, and(iv) from 0.0001 wt% to 0.005 wt%, or from 0.0001 wt% to 0.003 wt% of the catalyst, or titanium butoxide, wherein weight percent (wt%) is based on the total weight of the reaction mixture before the reaction occurs (hereafter interchangeably referred toas polyester polyol A).

[0047] In an embodiment, the polyester polyol component (A) of the present adhesive composition includes an enhancer in addition to (i) the dicarboxylic acid, (ii) the C3-C6 diol, and(iii) the glycol. Bounded by no particular theory, it is believed the enhancer provides additional improvement to compostability and performance for the adhesive composition. Nonlimiting examples of suitable enhancer include hydroxyl functionalized carboxylic acid, caprolactone, hydroxyalkanoate, isosorbide, 2,5-furandicarboxylic acid, and combinations thereof. A "hydroxyl functionalized carboxylic acid," as used herein, is a carboxylic acid with one or more hydroxyl groups in addition to the hydroxyl group present in the carboxylate moiety of the carboxylic acid. Nonlimiting examples of suitable hydroxyl functionalized carboxylic acid include lactic acid and glycolic acid.

[0048] In an embodiment, the polyester polyol component is the reaction product of a reaction mixture comprising, or consisting of:(i) from 35 wt% to 65 wt%, or from 45 wt% to 55 wt% of the dicarboxylic acid, or succinic acid,(ii) from 5 wt% to 25 wt%, or from 10 wt% to 20wt% of the unsaturated C3-C6 diol, or butane-l,4-diol,(iii) from 20 wt% to 40 wt%, or from 25 wt% to 35wt% of the glycol, or diethylene glycol,(iv) from 1 wt% to 10 wt% of a first enhancer, or lactic acid,(v) from 2 wt% to 15 wt% of a second enhancer, or caprolactone, and(vi) from 0.0001 wt% to 0.003 wt% of the catalyst, or titanium butoxide, wherein weight percent (wt%) is based on the total weight of the reaction mixture before the reaction occurs (hereafter interchangeably referred to as polyester polyol B).

[0049] The present adhesive composition includes (B) the aliphatic isocyanate. The aliphatic isocyanate is void of, or otherwise excludes, aromatic rings. Nonlimiting examples of suitable bio-based aliphatic isocyanate include 1,5-pentamethylene diisocyanate, poly(l,5- pentamethylene diisocyanate), and combinations thereof.

[0050] The polyester polyol component (A) is reacted with (B) the aliphatic isocyanate to form the present adhesive composition. The reaction of the adhesive composition in laminate isperformed at room temperature or elevated temperature from 25DC to less than 100°C or from 25°C to 50°C, to build up adhesion performance.

[0051] In an embodiment, the adhesive composition is the reaction product of an adhesive reaction mixture comprising, or consisting of(A) from 70 wt% to 90 wt%, or from 80 wt% to 85 wt% of the polyester polyol component, or polyester polyol A,(B) from 30 wt% to 10 wt%, or from 20 wt% to 15 wt% of the aliphatic isocyanate, or 1,5 pentamethylene diisocyanate, wherein the weight percent (wt%) is based on the total weight of the adhesive reaction mixture before the reaction occurs (hereafter interchangeably referred to as adhesivel). In a further embodiment, adhesivel has a DtCC value (as described below) of greater than 90% after 120 days.

[0052] In an embodiment, the adhesive composition is the reaction product of an adhesive reaction mixture comprising, or consisting of(A) from 70 wt% to 90 wt%, or from 80 wt%to 85 wt% of the polyester polyol component, or polyester polyol B,(B) from 30 wt% to 10 wt%, or from 20 wt% to 15 wt% of the aliphatic isocyanate, or 1,5- pentamethylene diisocyanate or poly(l,5-pentamethylene diisocyanate), wherein the weight percent (wt%) is based on the total weight of the adhesive reaction mixture before the reaction occurs (hereafter interchangeably referred to as adhesive2). In a furtherembodiment, adhesive2 has a DtCCh value (as described below) of greaterthan 90% after 120 days.

[0053] In an embodiment, the adhesive composition includes a solvent. The solvent is selected from ethyl acetate, butyl acetate, methylethylketone, methylbutylketone, water, and combinations thereof.B. Laminate

[0054] The present disclosure provides a laminate. The laminate includes a first substrate, a second substrate, and an adhesive layer between the first substrate and the second substrate. The adhesive layer is composed of the present adhesive composition. In particular, the adhesive layer is composed of the adhesive composition that is the reaction product of (A) the polyesterpolyol component composed of (i) the dicarboxylic acid, (ii) the C3-C5 diol, (iii) the glycol, and (iv) optional enhancer(s), and (B) the aliphatic isocyanate.

[0055] The laminate includes a first substrate and a second substrate. The first substrate and the second substrate may be the same or different. In an embodiment, the first substrate and the second substrate are the same, such that they have the identical compositions and identical structures.

[0056] In an embodiment, the first substrate and the second substrate each is a film. The film may be a monolayer film or a multilayer film. When the first substrate and / or the second substrate is a multilayer film, the multilayer film may include two, or three, or four, or five, or six, or seven, eight, nine, ten, or more layers.

[0057] In an embodiment, the laminate includes more than two substrates, or three, or four or more substrates with an adhesive layer between the substrates for adhering the substrates together.

[0058] In an embodiment, the film is a monolayer film with one, and only one, layer.

[0059] In an embodiment, the film includes a layer containing a component selected from ethylene-based polymer (PE), propylene-based polymer (PP), polyamide (such as nylon), polyester, ethylene vinyl alcohol (EVOH) copolymer, polyethylene terephthalate (PET), ethylene vinyl acrylate (EVA) copolymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ethylene butyl acrylate copolymer, ethylene acrylic acid copolymer, ethylene methacrylic acid copolymer, an ionomer of ethylene acrylic acid, an ionomer of methacylic acid, maleic anhydride grafted ethylene-based polymer, a polylactic acid (PLA), a polystyrene, a metal foil, a cellulose, cellophane, nonwoven fabric, and combinations thereof. A nonlimiting example of a suitable metal foil is aluminum foil. Each layer of a multilayer film may be formed from the same component, or from different components. In an embodiment, the film includes a layer containing metal foil.

[0060] In an embodiment, the first substrate and the second substrate each is composed of a compostable material for making a compostable laminate. The compostable material in the first substrate may be the same as, or different than, the compostable material in the second substrate. Nonlimiting examples of suitable compostable materials for the first substrate and / or the second substrate include films made of lignin, starch, cellulose material (paper,cardboard) polylactic acid (PLA), polylactic acid stereocomplexes (PLLA-PDLA), polyglycolic acid (PGA), cellophane, polypropylene carbonate (PPG), polybutylene succinate (PBS), polybutylene succinate-co- butylene adipate (PBSA), polybutylene succinate-co-butylene sebacate (PBSSe), polycaprolactone (PCL), and polypentadecanolide, polybutylene adipate- co-butyleneterephthalate (PBAT), polybutylene sebacate-co-butylene terephthalate (PBSeT), polybutylene azelate-co-butylene terephthalate (PBAzeT), polybutylene brassylate-co- butylene terephthalate (PBBrasT), poly-3- hydroxybutyrate (PHB), poly-3-hydroxybutyrate-co- 3-hydroxyvalerate (P(3HB)-co-P(3HV)), poly- 3-hydroxybutyrate-co-4-hydroxybutyrate (P(3HB)-co-P(4HB)), poly-3-hydroxybutyrate-co-3- hydroxyhexanoate (P(3HB)-co-P(3HH)), and combinations thereof.

[0061] In an embodiment, the first substrate and the second substate each has a thickness from 5 pm, or 10 pm, or 12 pm, or 15 pm, or 20 pm, or 21 pm to 23 pm, or 24 pm, or 25 pm, or 30 pm, or 35 pm, or 40 pm, or 45 pm, or 50 pm, or 100 pm, or 150 pm, or 200 pm, or 250 pm, or 300 pm, or 350 pm, or 400 pm, or 450 pm, or 500 pm.

[0062] Nonlimiting examples of suitable methods for applying the adhesive composition to the first substrate and / or to the second substrate include brushing, pouring, spraying, coating, rolling, spreading, and combinations thereof. In an embodiment, the adhesive composition is applied between the first substrate and the second substrate at a coat weight from 0.8 g / m2to 5.0g / m2, or from 1.0 g / m2to 4.0 g / m2, or from 1.5 g / m2to 3.0 g / m2, or from 1.8 g / m2to 2.5 g / m2.

[0063] In an embodiment, the adhesive composition is uniformly applied to the first substrate and then laminated to the second substrate with a laminator, or vice versa. A "uniform application" is a layer of the adhesive composition that is continuous (not intermittent) across a surface of the substrate, and of the same, or substantially the same, thickness across the surface of the substrate. In other words, the adhesive composition is uniformly applied to the first substrate and / or to the second substrate and directly contacts the substrate surface, and the adhesive composition is coextensive with, or substantially coextensive with, each substrate surface to bonding each other after curing.

[0064] In an embodiment, the adhesive layer is in direct contact with the first substrate and the adhesive layer is also in direct contact with the second substrate. The term "directly contacts,"or "in direct contact with," as used herein, is a layer configuration whereby a substrate is located immediately adjacent to the adhesive layer and no intervening layers, or no intervening structures, are present between the substrate and the adhesive layer.

[0065] In an embodiment, the adhesive layer is in direct contact with the first substrate and the adhesive layer is also in direct contact with the second substrate. The laminate has the following Structure (A):Structure (A)First Substrate / Adhesive Composition / Second Substrate.

[0066] In an embodiment, the laminate is formed with a laminator, such as a Nordmeccanica Labo Combi 400 laminator. In another embodiment, the laminate is formed with a hand laminator, such as Hot roll Laminator HL-200 from Chemlnstruments.

[0067] In an embodiment, the first substrate and the second substrate of the laminate each individually is composed of a compostable material selected from polylactic acid, polybutylene succinate, polycaprolactone, and cellulose material. The first substrate may be composed of the same compostable material as the second substrate. Alternatively, the first substrate is a different compostable material than the compostable material for the second substrate.

[0068] By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail in the following Examples.EXAMPLES

[0069] The materials used in the inventive examples ("IE") and comparative samples ("CS") are provided in Table 1 below.Table 1A. Synthesis of polyester polyol components 1, 3, 4.

[0070] A 3L multi-neck round bottom flask was dried in an oven and purged the nitrogen, and then charged with (i) succinic acid, (ii) butane diol ("BDO"), (iii) and diethylene glycol monomers each in the amounts set forth in Table 2 below (polyester polyols 1, 3, 4) and under ambient conditions. The system was pulled vacuum to less than 60 mTorr and refilled with nitrogen. After 4 cycles of vacuum / N? purging, the reactor was left under continuous N? flow, and slowly heated up. Once the reactor temperature reached 100°C, the overhead mechanical agitator was turned on slowly for stirring the mixture. The reaction temperature was then gradually increased to 150°C and held at this temperature until no water comes out, then slowly increase the temperature 5°C basis to 230°C. When about 95% of the theoretical water evolved, the acid value (AV) was monitored. The reactor was maintained at 230°C for 6 hours (hrs) until AV was less than 10 mg KOH / g. Then the catalyst (titanium butoxide) was added after the reaction was cooled down to less than 150°C, the resin mixture was heated back to 230°C. Maintaining the temperature, 550- 650 mTorr vacuum was applied for two hours, 450-550mTorr vacuum was applied for two hours, then 350-450mTorr vacuum was applied for one hour. The total cycle time was about 12 hrs. Then, the resin was cooled to 150°C, transferred and packaged in a glass jar. The final product was characterized with acid number, OH number, viscosity, and molecular weight by gel permeation chromatography (GPC). The polyester polyol components 1, 3, 4 synthesized herein are interchangeably referred to as respective polyester polyol 1, polyester polyol 3, and polyester polyol 4 in Table 2.B. Preparation of polyester polyol components 2 and 5.

[0071] A 3L multi-neck round bottom flask was dried in an oven and purged the nitrogen, and then charged with (i) succinic acid, (ii) BDO, (iii) diethylene glycol, and (iv) lactic acid each in the amounts set forth in Table 2 below (polyester polyols 2, 5) under ambient conditions. The system was pulled under vacuum to less than 60 mTorr and refilled with nitrogen. After 4 cycles of vacuum / N2 purging, the reactor was left under continuous N? flow, and slowly heated. Once the reactor temperature reached 100°C, the overhead mechanical agitator was turned on slowly for stirring the mixture. The reaction temperature was then gradually increased to 150°C and held at this temperature until no water evolved, then the temperature was slow increased 5°C basis to230°C. When about 95% of the theoretical water evolved, the acid value (AV) was monitored. The reactor was maintained at 230°C for 6hrs until AV was less than 10 mg KOH / g. Then the catalyst (titanium butoxide) was added after the reaction was cooled down to less than 150°C, the resin mixture was heated back to 230°C. Maintaining the temperature, 550-650 mTorr vacuum was applied for two hours, 450-550mTorr vacuum was applied for two hours, and 350-450mTorr vacuum was applied for one hour. The total cycle time was 12h. Then, the resin was cooled to about 150°C, and the acid number measured was less than 0.9mgKOH / g. The amount of (v) caprolactone (set forth in Table 2 below) was charged into reaction, the reaction mixture was heated to 180°C and maintained the temperature for 3hrs. FTIR tracked the reaction and no caprolactone monomer remained. Total cycle time of the synthesis was 16hrs. Then it was cooled to 150°C and transferred and packaged the product in a glass jar. The final product was characterized with acid number, OH number, viscosity, and molecular weight by gel permeation chromatography (GPC). The polyester polyol components 2 and 5 synthesized herein are interchangeably referred to as respective polyester polyol 2 and polyester polyol 5 in Table 2.

[0072] Table 2. Polyester polyol compositions and physical properties% - weight percent based on the total weight of the polyester polyolC. Performance evaluation

[0073] The new solvent free compostable adhesives were evaluated with PLA / / PLA-Seal film structure to compare with conventional solvent-free commercial adhesive MOR-FREE L75- 197 / CR-5. The mixing ratio of the adhesive compositions is shown in Table 3.

[0074] Table 3. Mixing ratio of the adhesives for making laminationwt% based on total weight of adhesive composition

[0075] For hand lamination, various polyester polyols and STABiO™ D370N (at the weight percentages shown in Table 3 below) were dissolved with a high-speed mixer at 1800 rpm for 1 minute to produce adhesive compositions, shown in Table 4 below.

[0076] Table 4. Formulation of adhesive compositions in solvent (solid content 40% by weight in solvent)D. Formation of a Laminate by a pilot laminator

[0077] PLA / adhesive / PLA-seal laminates were prepared by a pilot coater laminator, Labo Combi 400. For the comparative samples, 40°C temperature of the meteral roll was used. For the inventive examples, 60°C temperature of the meteral roll was used. The lamination was conducted at lOOft / min with inline corona treatment. The laminated films were cured at 25°C 50% humidity for two days, then kept in 45°C oven for curing. Table 5 shows the bond strength and Boil in bag bond ("BIB") strength. Table 6 shows the heat seal bond strength. FTIR spectra indicate that the NCO peak of the inventive examples IE1 and IE2 adhesives disappeared after two days at room temperature and after one day at 45°C, which indicates the full cure of the inventive adhesive compositions.E. Adhesion Results

[0078] Table 5. T-Peel bond strength of the laminating structures.*BIB: after Boil-in-Bag for 30min

[0079] Table 6. Heat seal bond strength of adhesives after 2-day at room temperature and5-days at 45 °C curing.

[0080] Inventive Example 3 (polyester polyol 3), Inventive example 4 (Polyester polyol 4), inventive example 5 (polyester polyol 5) and comparative sample 1 were evaluated by hand drawdown and follow up performance test after same condition curing. Due to hand drawdown and hand lamination used to prepare the laminates for test, ethyl acetate was used as the solvent to prepare the adhesive samples. After coating the adhesive on the substrate, it was dried in 90°C oven for lmin, then laminated with the second substrate with a hot roll hand laminator at 40psi. Results are provided in Table 7 below.

[0081] Table 7: T-Peel bond strength of the hand lamination structures.

[0082] Tables 5-7 show that IE1-3 are the same as, or better, in adhesive performance compared to conventional, non-compostable adhesive composition.F. Compostability evaluation

[0083] The compostability (biodegradability) of the inventive adhesive composition and comparative polymer material was evaluated according to the International Organization for Standardization (ISO) Guideline 14855-2: Method by analysis of evolved carbon dioxide (ISO 14855-2:2018(E)).

[0084] Test Material. The test materials consist of one natural biopolymer and six synthetic polymers as provided in Table 8 below.Table 8

[0085] Route of Administration. The test system and route of administration were selected based on the ISO Guideline 14855-2 (ISO, 2018), and in consideration of the physical / chemical properties of the test material. The test materials were added directly to the reaction vessels. To facilitate good contact between the test materials and the inoculum, the test materials were ground before being added to compost, except cellulose, LM10, and PVOH whose particle sizes were small enough.

[0086] Inoculum. The microbial inoculum consisted of compost collected from the West Madison Ag Research Station at the University of Wisconsin (Madison, Wisconsin) on October 19, 2022. The compost was collected two months prior to the initiation of the test and was stored in the laboratory until use. Prior to use, the compost was screened through a 4-mm sieve opening, and thoroughly homogenized with hands. The moisture content of the homogenized compost as well as its dry solid contents were determined gravimetrically to be 50% (wet wt.) and 50% (dry wt.), respectively. Similarly, the volatile solid content of the compost was determined to be 47% (dry wt.).

[0087] Test Procedure. The biodegradation reaction mixtures were prepared in a 1-gallon plastic bucket each containing a 240 g portion of the compost (50% moisture) plus 103 mL of deionized water, bringing to moisture to 65% (wet wt.). After the compost was mixed with water, the content was left to stand at room temperature for 24 h. Then 120 g (dry wt.) of prewashed sea sand was mixed with the compost, bringing the final mass to approximately 396 g of mixture (sand, compost, and water). Then 20 g (dry wt.) of reference material (cellulose) ortest materials was added to the mixture, which was homogenized with a spatula. The homogenized content was added to 1-L composting glass vessels. Inoculum blanks were also prepared in similar fashion, but no reference material or test material was added. The composting vessels were incubated in the dark or diffuse light for a specified period of time. The temperature was maintained to 58°C (±2°C). The composting vessels were shaken weekly to prevent extensive channeling, and to provide uniform attack on the test material and ensure adequate distribution of the moisture. Excessive moisture if any would be removed by dry air injection dry air, or by drainage via air inlet. At the weekly shaking and at the end of the test, visual observations were recorded with regard to compost structure, moisture content and color, fungal development, smell of the exhaust air, and sample disintegration. The incubation time was set to 45 days or longer. At the end of the test, the vessels were weighed with the contents and the dry solids concentration remaining in the composted material were determined. The pH was measured according to Test Methods D1293. If the pH was less than 7, the volatile fatty acids spectrum indicating souring of the contents in the composting vessel was measured in accordance with Practice D2908. The pH was measured by diluting the sample on a 5:1 w / w ratio of distilled water to compost inoculum or residue, mixed by shaking manually and measure immediately. If more than 2 g of volatile fatty acids per kilogram of dry matter in the composting vessel were formed, the test would be considered invalid.

[0088] Analytical Methods. Measurements of CO2 occurring in the headspace of the reaction vessels were performed using the Columbus Micro-Oxymax automated respirometry system (Columbus Instruments, Inc., Columbus, Ohio). This open flow respirometer system used a paramagnetic O2 sensor with a measurement range of 19 to 21.0% (volume) oxygen and a non-dispersive infrared CO2 detector with a measurement range of 0 to 0.8% (volume).Oxygen and CO2 measurements were normalized to a pressure of 800 mm Hg to compensate for any variation in ambient atmospheric pressure. Prior to initiating the test, the oxygen and CO2 sensors were calibrated at two concentrations spanning at least 50% of the measurement range, using certified calibration gases (Airgas Great Lakes, Inc.). The calibration also was verified after termination of the test, to document consistent operation of the sensors over the entire test period.

[0089] The pH of each reaction mixture was measured using an appropriate pH electrode and meter. The meter / electrode was calibrated at pH 4, 7, and 10 prior to each use.

[0090] Frequency of Sampling. Concentrations of oxygen and CO2 in the headspace of each reaction vessel were recorded at six-hour intervals over the entire experimental period.G. Study Specific Parameters

[0091] Carbon Dioxide Evolution. Carbon dioxide evolution was used as the primary indicator of biodegradation, with the percentage of test and / or reference material biodegraded calculated by subtracting the mean cumulative CO2 measurements for triplicate Inoculum Blanks from the cumulative CO2 measurements for each amended reaction mixture at each sampling interval, and by dividing the difference by the theoretical amount of carbon dioxide evolved by the reference or test material as follows:Where: Dtis the percent biodegradation.2)(CO2)T is the amount of carbon dioxide evolved in the vessel "VT" between the start of the test and time t expressed in milligrams. (C02)B is the amount of carbon dioxide evolved in the blank vessel "VB" between the start of the test and time t, expressed in milligrams.The CO2is the theoretical amount of carbon dioxide evolved by the test material, expressed in milligrams.ThCCh is expressed as mg CCh / mg material and was determined from the following formula:m is the mass of test material introduced into the test system, in milligrams.Xcis the carbon content of the test material, determined from the chemical formula or calculated from an elemental analysis and expressed as a mass fraction.MMCO2 is the molecular mass of carbon dioxide.MMc is the molecular mass of carbon.

[0092] The course of biodegradation is presented in Table 9 below as the mean percent biodegraded over 20, 40, 80, and 120 days of incubation.Table 9: Percent Biodegradation of reference and test materials.

[0093] Overall, the inventive example 1 and 2 each exhibit excellent compostability compared to the cellulose, polyvinyl acetate, partly hydrolyzed polyvinyl acetate (KURARAY POVAL™ LM10), and polyvinyl alcohol. The present adhesive composition (and IE1 and IE2 inparticular) has a DtCCh value greater than 90% after 120 days (IE1 107.2%, IE2 92.9%), as shown in Table 9.

[0094] It is specifically intended that the present disclosure not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.

Claims

CLAIMS1. An adhesive composition comprising: a reaction product comprising(A) a polyester polyol component comprising(i) a dicaboxylic acid,(ii) a Cs-Ce diol,(iii) a glycol; and(B) an aliphatic isocyanate.

2. The adhesive composition of claim 1, wherein the dicarboxylic acid is succinic acid.

3. The adhesive composition of any of claims 1-2, wherein the C3-C6 diol is butane diol.

4. The adhesive composition of any of claims 1-3, wherein the glycol is selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, and combinations thereof.

5. The adhesive composition of any of claims 1-5 wherein the polyester polyol component (A) is a reaction product of a reaction mixture comprising(i) from 35 wt% to 65 wt% of the dicarboxylic acid,(ii) from 5 wt% to 25 wt% of the unsaturated C3-C6 diol,(iii) from 20 wt% to 40 wt% of the glycol, and(iv) from 0.0001 wt% to 0.005 wt% of a catalyst.

6. The adhesive composition of any of claims 1-5 comprising an enhancer selected from the group consisting of a hydroxyl functionalized carboxylic acid, caprolactone, hydroxyalkanoate, isosorbide, 2,5-furandicarboxylic acid, and combinations thereof.

7. The adhesive composition of claim 6 wherein the polyester polyol component (A) is areaction product of a reaction mixture comprising(i) from 35 wt% to 65 wt% of the dicarboxylic acid,(ii) from from 5 wt% to 25 wt% of the C3-C6 diol,(iii) from 20 wt% to 40 wt% of the glycol,(iv) from 1 wt% to 5 wt% of a first enhancer,(v) from 2 wt% to 10 wt% of a second enhancer, and(vi) from 0.0001 wt% to 0.003 wt% of a catalyst.

8. The adhesive composition of any of claims 1-7, wherein the aliphatic isocyanate is selected from the group consisting of 1,5-pentamethylene diisocyanate, poly(l,5- pentamethylene diisocyanate), and combinations thereof.

9. The adhesive composition of any of claims 1-8 comprising(A) from 70 wt% to 90 wt%, of the polyester polyol component, and(B) from 10 wt% to 30 wt% of the aliphatic isocyanate.

10. The adhesive composition of any of claims 1-9, wherein the adhesive composition further comprises a solvent.

11. The adhesive composition of claim 10, wherein the solvent is selected from the group consisting of ethyl acetate, butyl acetate, methylethylketone, acetone, methylbutylketone, water, and combinations thereof.

12. The adhesive composition of any of claims 1-10 wherein the adhesive composition has as a DtCCh value of greater than 90% after 120 days.

13. A laminate comprising: a first substrate; a second substrate; and an adhesive layer between the first substrate and the second substrate, the adhesivelayer is an adhesive composition comprising a reaction product comprising(A) a polyester polyol component comprising(i) a dicarboxylic acid,(ii) a C3-C6 diol, and(iii) a glycol; and(B) an aliphatic isocyanate.

14. The laminate of claim 13 wherein the first substrate and the second substrate each individually is composed of a material selected from the group consisting of polylactic acid, polybutylene succinate, polycaprolactone, and a cellulose material.

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