Compostable adhesive compositions and laminates

Abstract

The present disclosure provides a composition. In one embodiment, an adhesive composition is provided. The adhesive composition comprises the reaction product of: (A) a polyester polyol component comprising (i) a dicarboxylic acid, (ii) a CB-CS diol, (iii) a diol; and (B) an aliphatic isocyanate. The present disclosure also provides a laminate having a first substrate and a second substrate and the inventive adhesive composition positioned between the first substrate and the second substrate.

Description

Background Technology

[0001] Adhesives are ubiquitous in the packaging industry. They bond different functional layers together to meet packaging requirements such as heat sealing, an attractive appearance, and suitable barrier properties. Adhesives also need to meet processability requirements, such as rapid curing, good heat resistance, sufficient chemical resistance, and compliance with government food regulations. Polyurethane-based adhesives are commonly used materials for packaging applications.

[0002] Sustainability is becoming increasingly important in the packaging industry. It is well known that packaging materials made from non-compostable and / or non-biodegradable plastic films have a negative impact on landfills. As consumers become more environmentally conscious, suppliers and processors are making progress in developing recyclable and biodegradable substrates for packaging to reduce the environmental impact of conventional flexible packaging.

[0003] Therefore, it is recognized in the art that there is a need to develop adhesive compositions that possess the necessary functions (processability, adhesive properties, etc.) and are readily degradable and / or easily decomposed upon exposure to stimuli in a bioactive environment. Compostable polyurethane-based adhesive compositions for packaging are also needed. Summary of the Invention

[0004] This disclosure provides a composition. In one embodiment, an adhesive composition is provided. The adhesive composition comprises a reaction product consisting of: (A) a polyester polyol component, the polyester polyol component comprising (i) a dicarboxylic acid, (ii) a C3-C6 diol, (iii) a diol; and (B) an aliphatic isocyanate.

[0005] This disclosure also provides a laminate. In one embodiment, the laminate provides and includes a first substrate and a second substrate. The adhesive composition of the present invention is positioned between the first substrate and the second substrate. The adhesive composition positioned between the first substrate and the second substrate comprises a reaction product consisting of: (A) a polyester polyol component, which includes (i) a dicarboxylic acid, (ii) a C3-C6 diol, (iii) a diol; and (B) an aliphatic isocyanate.

[0006] definition

[0007] Any reference to the periodic table is as in the version published by CRC Press, Inc. in 1990–1991. A group of elements in the table is referred to using a new notation for numbering the groups.

[0008] For the purposes of U.S. patent practice, any reference to a patent, patent application, or publication is incorporated herein by reference in its entirety (or its equivalent U.S. version thereof), especially the disclosure relating to definitions in the art (where there is no inconsistency with any definitions specifically provided in this disclosure) and common sense.

[0009] The numerical ranges disclosed herein include all values ​​from the lower limit to the upper limit, and include both the lower limit and the upper limit. For a range containing definite values ​​(e.g., the range from 1 or 2 or 3 to 5 or 6 or 7), any subrange between any two definite values ​​is included (e.g., the range 1 to 7 above includes subranges 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6, etc.).

[0010] Unless stated to the contrary, implied by the context, or as is customary in the art, all parts and percentages are based on weight, and all test methods are current methods as of the date of this disclosure.

[0011] "Bio-based" or "bio-based materials" refers to materials derived from plants and / or other naturally occurring agricultural, marine, and forestry materials. The benefits of bio-based materials lie in their origin and are recognized by industry. The term "bio-based" means raw materials that are at least partially or wholly derived from natural and / or renewable sources. Bio-based materials do not include petroleum-based materials. 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 originates.

[0012] As used in this article, "biomass" refers to organic materials.

[0013] The term "composition" refers to a mixture of materials comprising the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0014] The terms “comprising,” “including,” “having,” and their derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether or not they are specifically disclosed. For the avoidance of any doubt, unless stated to the contrary, all compositions claimed using the term “comprising” may include any additional additives, adjuvants, or compounds, whether in polymeric or other forms. In contrast, the term “consistently comprising” excludes any other components, steps, or procedures (except those not essential to operability) from the scope of any subsequent statements. The term “consisting of” excludes any components, steps, or procedures not specifically described or listed. Unless otherwise stated, the term “or” refers to the listed members individually and in any combination. Use of the singular includes use of the plural, and vice versa.

[0015] "Dicarboxylic acid" is a compound containing two carboxyl (-COOH) groups.

[0016] As used herein, a "diol" is a compound having at least two hydroxyl (--OH) groups attached to two different carbon atoms respectively. For example, the simplest diol is ethylene glycol, with the structure HO-CH2-CH2-OH.

[0017] An isocyanate is a chemical substance that contains at least one isocyanate group in its structure. The isocyanate group is represented by the formula: -N=C=O. Isocyanates containing more than one or at least two isocyanate groups are called "polyisocyanates". Isocyanates with two isocyanate groups are diisocyanates, and isocyanates with three isocyanate groups are triisocyanates, and so on. Isocyanates can be aromatic or aliphatic.

[0018] "Polyether" is a compound containing two or more ether bonds in a linear chain of identical atoms.

[0019] "Polyester" is a compound containing two or more ester bonds in a linear chain of identical atoms.

[0020] "Polyester polyol" is a compound that contains polyester and polyol.

[0021] A "polymer" is a polymeric compound prepared by polymerizing monomers (whether of the same or different types). Therefore, the general term polymer encompasses the term "homopolymer" (used to refer to a polymer prepared from only one type of monomer, where it should be understood that trace impurities may be incorporated into the polymer structure), and the term "interpolymer" (which is used interchangeably with the term "copolymer") includes binary copolymers (used to refer to polymers prepared from two or more different types of monomers), ternary copolymers (used to refer to polymers prepared from three different types of monomers), and polymers prepared from more than three different types of monomers. Trace impurities (e.g., catalyst residues) may be incorporated into and / or within the polymer. It also encompasses all forms of copolymers, such as random, block, etc. It should be noted that although polymers are often referred to as being "made from" one or more specified monomers, "based on" a specified monomer or monomer type, "containing" a specified monomer content, etc., in this context, the term "monomer" should be understood to refer to the polymer residue of the specified monomer rather than the unpolymerized material. Generally, polymers are referred to herein as "units" based on the polymeric form of the corresponding monomer.

[0022] "Polyols" are organic compounds containing multiple hydroxyl (-OH) groups. In other words, polyols contain at least two hydroxyl groups. Non-limiting examples of suitable polyols include diols (containing two hydroxyl groups) and triols (containing three hydroxyl groups) and polyols containing multiple hydroxyl groups.

[0023] "Soluble-free adhesives" are adhesive compositions that contain no or substantially no solvents.

[0024] "Solvent-based adhesives" are adhesive compositions containing any kind of organic solvent, such as ethyl acetate, methyl ethyl ketone (MEK), etc.

[0025] Test methods

[0026] Measured according to ASTM D 1386 / 7 acid value (Or acid value). An acid value is a measure of the amount of carboxylic acid present in a component or composition. An acid value is the number of milligrams of potassium hydroxide required to neutralize one gram of free carboxylic acid present in the substance. The unit of acid value is mg KOH / g.

[0027] Hydroxyl (OH) value The OH value is measured according to ASTM E1899-16. The OH value is a measure of the number of hydroxyl groups in a polyol. It is defined as the number of milligrams of potassium hydroxide (KOH) required to neutralize the acetic acid absorbed when acetylated one gram of a chemical containing free hydroxyl groups. The unit of OH value is mg KOH / g.

[0028] Boiling test inside the bag An 8-inch (20.32 cm) × 12-inch (30.48 cm) laminate is folded over itself to provide a 20.32 cm × 15.24 cm structure having a first side and a second side. Thus, both the first and second sides are formed of the same laminate. A first substrate (polyethylene (“PE” film) on the first side contacts a first substrate (PE film) on the second side. The structure has four edges, including a folded edge and three open edges. The two open edges are heat-sealed to form a pouch. The heat-sealing is performed at 140°C and a pressure of 300 N / 15 mm for 1 second. Two to three pouches are prepared for each embodiment.

[0029] Fill each pouch with 180 mL of broth (Morton broth, a mixture of soybean oil, tomato sauce, and vinegar in a 1:1:1 ratio) through the remaining open edge. Avoid splashing the broth onto the heat-sealed area to prevent heat-seal failure. After filling, heat-seal the open edge in a manner that minimizes air trapping within the closed pouch. Each closed pouch has four sealing edges and an internal void of 18.82 cm × 13.74 cm (filled with broth). Visually inspect the integrity of each heat seal to ensure there are no defects in the seal that could cause leakage during testing. Pouches with suspected defects are discarded and replaced.

[0030] Fill a pot with 2 / 3 water and bring it to a boil. The pot should have a lid to minimize water and steam loss. Observe the pot during testing to ensure there is enough water to maintain a boil. Place the small bag individually in the boiling water and keep it in the boiling water for 30 minutes. Then remove the small bag from the boiling water and visually inspect it for gaps, bubbles, blistering, delamination, and / or leakage.

[0031] Cut open the pouch, empty the soup, and rinse with soap and water. Cut one or more strips (15mm x 175mm) of the laminate from the pouch (excluding the heat-sealed area). Measure the adhesive strength of the laminate according to the 90°T peel test as described above. Measure the heat-sealed strength of the laminate according to the heat-sealed strength test described above. After emptying the soup from the pouch, the adhesive strength and heat-sealed strength should be measured as soon as possible. Visually inspect the inside of the pouch for defects.

[0032] Adhesive strength (180°T-peel test) Bond strength was measured using a 180° manual peel test. After curing for two days in an oven at 40°C, the laminate was cut into 175mm x 15mm strips (each strip having a 175mm x 15mm adhesive area) for initial T-peel bond strength testing. Bond strength was also measured after a 5-day further curing and a 12-day further curing, following an in-bag boiling test. The Instron 5943 peel tester was set to a crosshead speed of 254mm / min. During testing, the tail of each strip was gently pulled with a finger to ensure the tail remained at 90° to the peel direction and the stretch direction was 180°. o The average bond strength (expressed as grams per 25.4 mm (g / 25.4 mm)) was determined by the force versus distance curve. Three samples were tested, and the average "bond strength" was reported.

[0033] Brinell viscosity Measurements were taken using a Bülow viscometer DVII+ with a No. 27 rotor at 20 rpm and a given temperature.

[0034] CompostabilityThe terms “compostable” and “compostability” encompass factors such as biodegradability, disintegration, and ecotoxicity. The terms “biodegradable,” “biodegradable,” and variations thereof refer to the property of a material to be degraded by microorganisms. Biodegradable means that the material decomposes over a period of time through the action of microorganisms such as bacteria, fungi, enzymes, and / or viruses. The term “disintegration,” and variations thereof, refers to the extent to which a material decomposes and disintegrates. Compostability refers to the ability of a material to be biodegraded directly into carbon dioxide. Ecotoxicity testing determines whether the material, after composting, exhibits any inhibitory effect on plant growth or the survival of soil or other animal populations. Biodegradability and compostability can be measured by visually inspecting substrates exposed to biological inoculants such as bacteria, fungi, enzymes, and / or viruses to monitor degradation. Alternatively, biodegradable substrates conform to ASTM Standard D6400; and alternatively, biodegradable substrates conform to ASTM Standard D6868-03.

[0035] By using Thermo Scientific with iD7 ATR probe ™ Nicolet ™ iS ™ 5. FTIR spectroscopy was used to scan the adhesive composition sample to obtain... FTIR (Fourier transform infrared spectroscopy) spectrum.

[0036] Gel permeation chromatography (GPC) The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polyester polyols were determined by gel permeation chromatography (GPC). Samples for GPC analysis were prepared by dissolving approximately 20 mg of sample in 10 g of tetrahydrofuran (THF). GPC separations were performed on a Waters Alliance HPLC system using Agilent PLgel 5 μm particle size columns (a set of four columns with pore sizes of 50 Å, 100 Å, 1000 Å, and 10000 Å). Calibration was performed using polystyrene standards (PS EasiVials) from Agilent Technologies, prepared in THF.

[0037] Analysis conditions :

[0038] Column temperature: 40℃

[0039] • Eluent: Tetrahydrofuran, unstable

[0040] • Flow rate: 1.0 mL / min

[0041] • Injection volume: 100µL

[0042] • Sample concentration: 2.0 mg / mL for polyhydroxy compounds, and approximately 10 mg / mL for prepolymers.

[0043] Analysis time: 45 minutes

[0044] • Detectors: Waters refractive index detector and Waters 2489 UV / Vis detector 254nm

[0045] Molecular weight <1000 When integrating and quantifying GPC peaks, the percentage of polymers with molecular weights below 1000 is calculated. The Waters Alliance HPLC system software determines how many peaks fall within the 1000 range based on the calibration curve used for integration. Integration is performed based on the retention times of the standards used for calibration and the retention times of the sample peaks. Results are reported as a percentage (%).

[0046] Molecular weight <500 When integrating and quantifying peaks, the percentage of polymers with molecular weights below 500 is calculated. The software determines how many peaks fall within the 500 range based on the calibration curve used for integration. Integration is performed based on the retention times of the standards used for calibration and the retention times of the sample peaks. Results are reported as a percentage (%).

[0047] Heat sealing strength The laminate was heat-sealed for 1 second at a sealing temperature of 160°C and a pressure of 40 PSI in an HSG-C heat-sealing machine (available from Brugger), then cooled to room temperature (23°C) and cut into 175mm × 15mm strips (each strip having a heat-sealed area of ​​175mm × 15mm). The heat-sealing strength of the strips was measured using a 5940 series single-column benchtop system (available from Instron) with a crosshead speed set to 254mm / min. Three samples were tested, and the average heat-sealing strength was reported in grams per 25.4mm (g / 25.4mm).

[0048] Measured according to ASTM D2572-97 isocyanate group The weight content of (NCO). The isocyanate index, or "NCO index", is the molar ratio of the amount of isocyanate groups in the isocyanate component to the amount of hydroxyl groups in the dimer polyester polyol component. The NCO index is calculated according to the following equation (1):

[0049]

[0050] Particle sizeParticle size analysis was performed using a Malvern Mastersizer 3000 laser diffractometer equipped with a Hydro LV liquid dispersion unit. To prepare the sample for analysis, 200 mg of powder was pre-dispersed in 10 mL of a 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% opacity level was reached. Particle size distribution was calculated using a fitted model with RI=1.50 and AI=0.01. Percentile particle size (Dv90) was used for comparison; size units are in micrometers. Detailed Implementation

[0051] This disclosure provides an adhesive composition. In one embodiment, the adhesive composition is a reaction product of (A) a polyester polyol component and (B) an aliphatic isocyanate. (A) The polyester polyol component is a reaction product of (i) a dicarboxylic acid, (ii) a C3-C6 diol, and (iii) a diol.

[0052] A. Adhesive composition

[0053] The adhesive composition of the present invention comprises (A) a polyester polyol component. The polyester polyol component is a reaction product of (i) a dicarboxylic acid, (ii) a C3-C6 diol and (iii) a diol.

[0054] In one embodiment, the dicarboxylic acid is an aliphatic dicarboxylic acid. Non-limiting examples of suitable aliphatic dicarboxylic acids include C2-C... 20 Dicarboxylic acids, such as cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, itaconic acid, malonic acid, octanoic acid, 2-methylsuccinic acid, 3,3-diethylglutaric acid, 2,2-dimethylsuccinic acid, succinic acid, trimellitic acid, and dodecanedicarboxylic acid (C 12 (and combinations thereof). In one embodiment, the aliphatic dicarboxylic acid is a C2-C6 dicarboxylic acid, such as succinic acid.

[0055] (A) The polyester polyol component includes C3-C6 diols. The C3-C6 diols are saturated C3-C6 diols. Non-limiting examples of suitable C3-C6 diols include propane-1,3-diol, butane-1,4-diol, and combinations thereof. In one embodiment, the C3-C6 diol is butane-1,4-diol.

[0056] (A) The polyester polyol component includes a diol. Non-limiting examples of suitable diols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, and combinations thereof. In one embodiment, the diol is diethylene glycol.

[0057] In one embodiment, a catalyst is used to promote the reaction of (i) dicarboxylic acid, (ii) C3-C6 diol, and (iii) diol. Non-limiting examples of suitable catalysts include butoxytitanium, isobutoxytitanium, propoxytitanium, or other alkoxides and combinations thereof. The polycondensation reaction of (i) dicarboxylic acid, (ii) C3-C6 diol, and (iii) diol is carried out under nitrogen protection. The reaction begins at 150°C, is gradually increased to 230°C while continuously removing moisture, and finally a vacuum is applied to drive the reaction to completion.

[0058] In one embodiment, the polyester polyol component (A) is a reaction product of the reaction mixture, which comprises or consists of the following:

[0059] (i) 35% to 65% by weight, or 45% to 55% by weight, of dicarboxylic acids, such as succinic acid,

[0060] (ii) 5% to 25% by weight, or 10% to 20% by weight, of C3-C6 diols or 1,4-butanediol.

[0061] (iii) 20% to 40% by weight, or 25% to 35% by weight, of diols or diethylene glycol, and

[0062] (iv) 0.0001% to 0.005% by weight, or 0.0001% to 0.003% by weight of catalyst, or butoxytitanium, wherein the weight percentage (wt%) is based on the total weight of the reaction mixture (hereinafter interchangeably referred to as polyester polyol A) prior to the reaction.

[0063] In one embodiment, the polyester polyol component (A) of the adhesive composition of the present invention includes a reinforcing agent in addition to (i) dicarboxylic acid, (ii) C3-C6 diol, and (iii) diol. Without being bound by any particular theory, the reinforcing agent is believed to provide additional improvements to the compostability and performance of the adhesive composition. Non-limiting examples of suitable reinforcing agents include hydroxy-functionalized carboxylic acids, caprolactone, hydroxyalkyl esters, isosorbide, 2,5-furandicarboxylic acid, and combinations thereof. As used herein, a “hydroxy-functionalized carboxylic acid” is a carboxylic acid having one or more hydroxyl groups in addition to the hydroxyl group present in the carboxylic ester moiety of the carboxylic acid. Non-limiting examples of suitable hydroxy-functionalized carboxylic acids include lactic acid and glycolic acid.

[0064] In one embodiment, the polyester polyol component is a reaction product of the reaction mixture, which comprises or consists of the following:

[0065] (i) 35% to 65% by weight, or 45% to 55% by weight, of dicarboxylic acids, such as succinic acid,

[0066] (ii) 5% to 25% by weight, or 10% to 20% by weight, of unsaturated C3-C6 diols or 1,4-butanediol.

[0067] (iii) 20% to 40% by weight, or 25% to 35% by weight, of diol or diethylene glycol.

[0068] (iv) 1% to 10% by weight of a first reinforcing agent or lactic acid

[0069] (v) 2% to 15% by weight of a second reinforcing agent or caprolactone, and

[0070] (vi) 0.0001% to 0.003% by weight of catalyst, or butoxytitanium, wherein the weight percentage (%) is based on the total weight of the reaction mixture (hereinafter interchangeably referred to as polyester polyol B) prior to the reaction.

[0071] The adhesive compositions of the present invention comprise (B) an aliphatic isocyanate. The aliphatic isocyanate contains no aromatic ring or otherwise excludes it. Non-limiting examples of suitable bio-based aliphatic isocyanates include 1,5-pentamethylene diisocyanate, poly(1,5-pentamethylene diisocyanate), and combinations thereof.

[0072] Polyester polyol component (A) reacts with aliphatic isocyanate (B) to form the adhesive composition of the present invention. The reaction of the adhesive composition in the laminate is carried out at room temperature or at elevated temperatures from 25°C to less than 100°C or from 25°C to 50°C to establish adhesive properties.

[0073] In one embodiment, the adhesive composition is a reaction product of an adhesive reaction mixture, the adhesive reaction mixture comprising or consisting of the following:

[0074] (A) 70% to 90% by weight, or 80% to 85% by weight, of polyester polyol component or polyester polyol A.

[0075] (B) 30% to 10% by weight, or 20% to 15% by weight, of an aliphatic isocyanate or 1,5-pentamethylene diisocyanate, wherein the weight percentage (wt%) is based on the total weight of the binder reaction mixture (hereinafter interchangeably referred to as binder 1) prior to the reaction. In another embodiment, binder 1 has a DtCO2 value greater than 90% after 120 days (as described below).

[0076] In one embodiment, the adhesive composition is a reaction product of an adhesive reaction mixture, the adhesive reaction mixture comprising or consisting of the following:

[0077] (A) 70% to 90% by weight, or 80% to 85% by weight, of polyester polyol component or polyester polyol B.

[0078] (B) 30% to 10% by weight, or 20% to 15% by weight, of an aliphatic isocyanate or 1,5-pentamethylene diisocyanate or poly(1,5-pentamethylene diisocyanate), wherein the weight percentage (wt%) is based on the total weight of the binder reaction mixture (hereinafter interchangeably referred to as binder 2) prior to the reaction. In another embodiment, binder 2 has a DtCO2 value greater than 90% after 120 days (described below).

[0079] In one embodiment, the adhesive composition comprises a solvent. The solvent is selected from ethyl acetate, butyl acetate, methyl ethyl ketone, methyl butyl ketone, water, and combinations thereof.

[0080] B. Laminate

[0081] This disclosure provides a laminate. The laminate includes a first substrate, a second substrate, and a solvent-free adhesive layer located between the first substrate and the second substrate. The adhesive layer is composed of the adhesive composition of the present invention. In particular, the adhesive layer is composed of an adhesive composition that is a reaction product of (A) a polyester polyol component and (B) an aliphatic isocyanate, the polyester polyol component being composed of (i) a dicarboxylic acid, (ii) a C3-C6 diol, (iii) a diol, and (iv) an optional reinforcing agent.

[0082] The laminate includes a first substrate and a second substrate. The first substrate and the second substrate may be the same or different. In one embodiment, the first substrate and the second substrate are the same, such that they have the same composition and the same structure.

[0083] In one embodiment, the first substrate and the second substrate are each a membrane. The membrane can be a single-layer membrane or a multilayer membrane. When the first substrate and / or the second substrate are multilayer membranes, the multilayer membrane may include two, three, four, five, six, seven, eight, nine, ten or more layers.

[0084] In one embodiment, the laminate includes more than two, three, four or more substrates, wherein an adhesive layer for adhering the substrates together is provided between the substrates.

[0085] In one embodiment, the membrane is a single-layer membrane having one and only one layer.

[0086] In one embodiment, the membrane includes layers comprising a selection of components: ethylene-based polymers (PE), propylene-based polymers (PP), polyamides (such as nylon), polyesters, ethylene vinyl alcohol (EVOH) copolymers, polyethylene terephthalate (PET), ethylene vinyl acrylate (EVA) copolymers, ethylene methyl acrylate copolymers, ethylene ethyl acrylate copolymers, ethylene butyl acrylate copolymers, ethylene acrylic acid copolymers, ethylene methacrylic acid copolymers, ethylene acrylic acid ionomers, methacrylic acid ionomers, maleic anhydride-grafted ethylene-based polymers, polylactic acid (PLA), polystyrene, metal foil, cellulose, cellophane, nonwoven fabrics, and combinations thereof. A non-limiting example of a suitable metal foil is aluminum foil. Each layer of the multilayer membrane may be formed from the same components or from different components. In one embodiment, the membrane includes a layer comprising a metal foil.

[0087] In one embodiment, the first substrate and the second substrate are each composed of compostable materials used to manufacture the compostable laminate. The compostable material in the first substrate may be the same as or different from the compostable material in the second substrate. Non-limiting examples of suitable compostable materials for the first substrate and / or the second substrate include films made of lignin, starch, cellulose materials (paper, paperboard), polylactic acid (PLA), polylactic acid stereocomplex (PLLA-PDLA), polyglycolic acid (PGA), cellophane, polypropylene carbonate (PPG), polybutylene succinate (PBS), polybutylene succinate-copolybutylene adipate (PBSA), polybutylene succinate-copolybutylene sebacate (PBSSe), polycaprolactone (PCL) and polypentadecanolactone, polybutylene adipate-copolybutylene terephthalate (PBAT), polybutylene terephthalate (PBAT), and polybutylene terephthalate (PBAT). Butylene diacid-copolybutylene terephthalate (PBSeT), polybutylene azelaate-copolybutylene terephthalate (PBAzeT), polybutylene brassinolate-copolybutylene terephthalate (PBBrasT), poly-3-hydroxybutyrate (PHB), poly-3-hydroxybutyrate-copoly-3-hydroxyvalerate (P(3HB)-co-P(3HV)), poly-3-hydroxybutyrate-copoly-4-hydroxybutyrate (P(3HB)-co-P(4HB)), poly-3-hydroxybutyrate-copoly-3-hydroxyhexanoate (P(3HB)-co-P(3HH)), and combinations thereof.

[0088] In one embodiment, the thickness of the first substrate and the second substrate is 5µm, or 10µm, or 12µm, or 15µm, or 20µm, or 21µm to 23µm, or 24µm, or 25µm, or 30µm, or 35µm, or 40µm, or 45µm, or 50µm, or 100µm, or 150µm, or 200µm, or 250µm, or 300µm, or 350µm, or 400µm, or 450µm, or 500µm.

[0089] Non-limiting examples of suitable methods for applying the adhesive composition to a first and / or second substrate include brushing, casting, spraying, coating, roller coating, spreading, and combinations thereof. In one embodiment, the adhesive composition is applied at a coating amount of 0.8 g / m². 2 Up to 5.0g / m 2 or 1.0g / m 2 Up to 4.0g / m 2 or 1.5g / m 2 Up to 3.0g / m 2 or 1.8g / m 2 Up to 2.5g / m 2 It is applied between the first substrate and the second substrate.

[0090] In one embodiment, the adhesive composition is uniformly applied to a first substrate and then laminated to a second substrate using a laminator, and vice versa. "Uniform application" means that the adhesive composition layer is continuous (not discontinuous) on the surface of the substrate and has the same or substantially the same thickness across the entire surface of the substrate. In other words, the adhesive composition is uniformly applied to the first and / or second substrates, directly contacting the substrate surfaces, and the adhesive composition co-extrudes or substantially co-extrudes with each substrate surface to bond with each other after curing.

[0091] In one embodiment, the adhesive layer is in direct contact with a first substrate and also in direct contact with a second substrate. As used herein, the terms "direct contact" or "direct contact with" refer to a layer configuration in which the substrate is positioned immediately adjacent to the adhesive layer, and there is no intermediate layer or intermediate structure between the substrate and the adhesive layer.

[0092] In one embodiment, the adhesive layer is in direct contact with a first substrate, and the adhesive layer is also in direct contact with a second substrate. The laminate has the following structure (A):

[0093] Structure (A)

[0094] First substrate / adhesive composition / second substrate.

[0095] In one embodiment, the laminate is formed using a laminator (such as a Nordmeccanica Labo Combi 400 laminator). In another embodiment, the laminate is formed using a manual laminator (such as a ChemInstruments HL-200 hot roller laminator).

[0096] In one embodiment, the first and second substrates of the laminate are each individually composed of a compostable material selected from polylactic acid, polybutylene succinate, polycaprolactone, and cellulose materials. The first substrate may be composed of the same compostable material as the second substrate. Alternatively, the compostable material of the first substrate may be different from that of the second substrate.

[0097] By way of example and not limitation, some embodiments of this disclosure will now be described in detail in the following examples.

[0098] Example

[0099] The materials used in the embodiments of the present invention (“IE”) and the comparative samples (“CS”) are provided in Table 1 below.

[0100] Table 1

[0101] A. Synthesis of polyester polyol components 1, 3, and 4 .

[0102] A 3L multi-necked round-bottom flask was dried in an oven and purged with nitrogen. Then, under ambient conditions, (i) succinic acid, (ii) butanediol (“BDO”), and (iii) diethylene glycol monomers were added in the amounts shown in Table 2 (Polyester Polyols 1, 3, 4). The system was evacuated to below 60 mTorr and refilled with nitrogen. After four vacuum / N2 purging cycles, the reactor was placed under a continuous N2 stream and slowly heated. Once the reactor temperature reached 100°C, the top mechanical stirrer was slowly turned on to stir the mixture. The reaction temperature was then gradually increased to 150°C and maintained at that temperature until no more water was expelled, followed by a slow increase to 230°C in 5°C increments. The acid value (AV) was monitored when approximately 95% of the theoretical water had distilled off. The reactor was maintained at 230°C for 6 hours until AV was less than 10 mg KOH / g. The reaction mixture was then cooled to below 150°C, and the catalyst (butoxytitanium) was added. The resin mixture was then heated back to 230°C. Maintain the temperature and apply a vacuum of 550 mTorr to 650 mTorr for 2 hours, then a vacuum of 450 mTorr to 550 mTorr for 2 hours, followed by a vacuum of 350 mTorr to 450 mTorr for 1 hour. The total cycle time is approximately 12 hours. The resin is then cooled to 150°C, transferred, and packaged in glass jars. The final product was characterized by gel permeation chromatography (GPC) using acid value, OH value, viscosity, and molecular weight. The polyester polyol components 1, 3, and 4 synthesized in this paper are interchangeably referred to as the corresponding polyester polyol 1, polyester polyol 3, and polyester polyol 4 in Table 2.

[0103] B. Preparation of polyester polyol components 2 and 5 .

[0104] A 3L multi-necked round-bottom flask was dried in an oven and purged with nitrogen. Then, under ambient conditions, (i) succinic acid, (ii) BDO, (iii) diethylene glycol, and (iv) lactic acid were added in the amounts shown in Table 2 (polyester polyols 2 and 5). The system was evacuated to below 60 mTorr and refilled with nitrogen. After four vacuum / N2 purging cycles, the reactor was placed under a continuous N2 stream and slowly heated. Once the reactor temperature reached 100°C, the top mechanical stirrer was slowly turned on to stir the mixture. The reaction temperature was then gradually increased to 150°C and maintained at this temperature until no water distilled off, followed by a slow increase to 230°C in 5°C increments. The acid value (AV) was monitored when approximately 95% of the theoretical water had distilled off. The reactor was maintained at 230°C for 6 hours until AV was less than 10 mg KOH / g. The reaction mixture was then cooled to below 150°C, and the catalyst (butoxytitanium) was added. The resin mixture was then heated back to 230°C. The temperature was maintained, and a vacuum of 550 mTor to 650 mTor was applied for 2 hours, followed by a vacuum of 450 mTor to 550 mTor for 2 hours, and then a vacuum of 350 mTor to 450 mTor for 1 hour. The total cycle time was 12 hours. The resin was then cooled to approximately 150 °C, and the measured acid value was less than 0.9 mg KOH / g. A certain amount of (v) caprolactone (listed in Table 2 below) was added to the reaction mixture, and the reaction mixture was heated to 180 °C and maintained at this temperature for 3 hours. FTIR tracing of the reaction showed no caprolactone monomer residue. The total cycle time for the synthesis was 16 hours. The mixture was then cooled to 150 °C, and the product was transferred and packaged in glass jars. The final product was characterized by gel permeation chromatography (GPC) using acid value, OH value, viscosity, and molecular weight. Polyester polyol components 2 and 5 synthesized herein are interchangeably referred to as the corresponding polyester polyol 2 and polyester polyol 5 in Table 2.

[0105] Table 2. Polyester Polyol Compositions and Physical Properties

[0106] % - weight percentage, based on the total weight of the polyester polyol.

[0107] C. Performance Evaluation

[0108] The novel solvent-free compostable adhesive was evaluated using a PLA / / PLA-sealing membrane structure and compared with the conventional solvent-free commercial adhesive MOR-FREE L75-197 / CR-5. The mixing ratios of the adhesive compositions are shown in Table 3.

[0109] Table 3. Mixing ratio of adhesives used in lamination preparation

[0110] weight% - based on the total weight of the adhesive composition

[0111] For manual lamination, various polyester polyols and STABiO™ D370N (weight percentages shown in Table 3 below) was dissolved in a high-speed mixer at 1800 rpm for 1 minute to produce an adhesive composition, as shown in Table 4 below.

[0112] Table 4. Formulation of adhesive compositions in solvents (solvent content is 40% by weight)

[0113]

[0114] D. Forming laminates using an experimental laminator

[0115] The PLA / adhesive / PLA sealing laminate was prepared using an experimental coating and laminating machine, Labo Combi 400. For comparative samples, a metal roller temperature of 40°C was used. For embodiments of the invention, a metal roller temperature of 60°C was used. Lamination was performed with in-line corona treatment at 100 ft / min. The laminates were cured at 25°C and 50% humidity for two days, then maintained in a 45°C oven for further curing. Table 5 shows the bond strength and the boil-in-bag (BIB) bond strength. Table 6 shows the heat-sealed bond strength. FTIR spectroscopy showed that the NCO peaks of the IE1 and IE2 adhesives of the embodiments of the invention disappeared after two days at room temperature and one day at 45°C, indicating that the adhesive compositions of the invention were fully cured.

[0116] E. Adhesion Results

[0117] Table 5. T-peel bond strength of laminated structures .

[0118] *BIB: Boil in the bag for 30 minutes.

[0119] Table 6. Heat-sealing bond strength of the adhesive after 2 days at room temperature and 5 days at 45°C .

[0120]

[0121] Example 3 (polyester polyol 3), Example 4 (polyester polyol 4), Example 5 (polyester polyol 5), and Comparative Sample 1 were evaluated by manual coating and subsequent performance testing under the same conditions. Ethyl acetate was used as the solvent to prepare the adhesive samples for manual coating and manual lamination of the test laminates. After the adhesive was applied to the substrate, it was dried in a 90°C oven for 1 minute and then laminated with a second substrate at 40 psi using a hot roller manual laminator. The results are provided in Table 7 below.

[0122] Table 7: T-peel bond strength of manually laminated structures .

[0123]

[0124] Tables 5 to 7 show that IE1-3 has the same or better adhesive performance than conventional non-compostable adhesive compositions.

[0125] F. Compostability Assessment

[0126] According to International Organization for Standardization (ISO) Guide 14855-2: Method for evaluating the compostability (biodegradability) of the adhesive compositions of the present invention and comparing polymer materials by analyzing the carbon dioxide released (ISO 14855-2:2018(E)).

[0127] Test materials The test material consists of one natural biopolymer and six synthetic polymers, as provided in Table 8 below.

[0128] Table 8

[0129]

[0130] Application route The testing system and application route were selected based on ISO Guideline 14855-2 (ISO, 2018) and taking into account the physical / chemical properties of the test materials. The test materials were added directly to the reaction vessel. To promote adequate contact between the test materials and the inoculum, all test materials except cellulose, LM10, and PVOH (which were already sufficiently fine in particle size) were ground before being added to the compost.

[0131] Inoculation The microbial inoculum consisted of compost collected on October 19, 2022, from the West Madison Ag Research Station at the University of Wisconsin-Madison, Wisconsin. The compost was collected two months prior to the start of testing and stored in the laboratory until use. Before use, the compost was sieved through a 4 mm sieve and thoroughly homogenized by hand. The moisture content and dry solids content of the homogenized compost were determined by gravimetric analysis to be 50% (wet weight) and 50% (dry weight), respectively. Similarly, the volatile solids content of the compost was determined to be 47% (dry weight).

[0132] Test programPrepare a biodegradable reaction mixture in 1-gallon plastic buckets, each containing 240 g of compost (50% moisture) plus 103 mL of deionized water to achieve a moisture content of 65% (wet weight). After mixing the compost and water, allow the contents to stand at room temperature for 24 hours. Then, mix 120 g (dry weight) of pre-washed sea sand with the compost to achieve a final mass of approximately 396 g of mixture (sand, compost, and water). Then, add 20 g (dry weight) of reference material (cellulose) or test material to the mixture and homogenize it with a spatula. Add the homogenized contents to 1-L compost glass containers. An inoculum blank is also prepared in a similar manner, but without the addition of reference material or test material. Incubate the compost containers in darkness or diffused light for a specified period of time. Maintain the temperature at 58°C (±2°C). Shake the compost containers weekly to prevent excessive channeling, ensure uniform decomposition of the test material, and ensure adequate moisture distribution. Excess moisture (if present) will be removed by injecting dry air or by draining water through the air inlet. Visual observations regarding compost structure, moisture content and color, fungal development, exhaust odor, and sample disintegration will be recorded at the end of each weekly shake and test. Incubation time should be at least 45 days. At the end of the test, the container and its contents will be weighed together, and the concentration of remaining dry solids in the composted material will be determined. pH will be measured according to Test Method D1293. If pH is less than 7, the volatile fatty acid profile indicating acidification of the contents in the compost container will be measured according to Practice D2908. The sample will be diluted with distilled water at a ratio of 5:1 (by weight) to the compost inoculum or residue, and the pH will be measured immediately after hand-shaking to mix. If more than 2 g of volatile fatty acids are formed per kilogram of dry matter in the compost container, the test will be considered invalid.

[0133] Analytical methods CO2 generated in the headspace of the reaction vessel was measured using the Columbus Micro-Oxymax automated breath measurement system (Columbus Instruments, Inc., Columbus, Ohio). This open-system breath measurement system employs a paramagnetic O2 sensor and a non-dispersive infrared CO2 detector, with measurement ranges of 19% to 21.0% (volume fraction) for oxygen and 0% to 0.8% (volume fraction) for carbon dioxide. Oxygen and CO2 measurements were normalized to a pressure of 800 mm Hg to compensate for any variations in ambient atmospheric pressure. Prior to testing, the oxygen and CO2 sensors were calibrated at two concentrations using certified calibration gas (Airgas Great Lakes) covering at least 50% of the sensor's range. Calibration was also validated after testing to document consistent sensor operation throughout the testing period.

[0134] Measure the pH of each reaction mixture using an appropriate pH electrode and meter. Calibrate the meter / electrode at pH 4, 7, and 10 before each use.

[0135] sampling frequency Throughout the experiment, the oxygen and CO2 concentrations in the headspace of each reaction vessel were recorded at 6-hour intervals.

[0136] G. Studying specific parameters

[0137] carbon dioxide release Carbon dioxide release was used as the primary indicator of biodegradation, where the percentage of biodegradation in the test and / or reference materials was calculated by subtracting the average cumulative CO2 measurement of three inoculum blanks from the cumulative CO2 measurement of each corrected reaction mixture at each sampling interval, and dividing the difference by the theoretical amount of carbon dioxide released from the reference or test material, as follows:

[0138]

[0139] Where: D t It represents the percentage of biodegradation.

[0140] It is the amount of carbon dioxide released in container "VT" between the start of the test and time t, expressed in milligrams.

[0141] It is the amount of carbon dioxide released in the blank container "VB" between the start of the test and time t, expressed in milligrams.

[0142] It is the theoretical amount of carbon dioxide released by the test material, expressed in milligrams.

[0143] ThCO2 is expressed as mg CO2 / mg material and is determined by the following formula:

[0144]

[0145] m is the mass of the test material introduced into the test system, expressed in milligrams.

[0146] X c It tests the carbon content of the material, determined by its chemical formula, or

[0147] It is calculated by elemental analysis and expressed as a mass fraction.

[0148] MM CO2 It is the molecular mass of carbon dioxide.

[0149] MM c That is the molecular weight of carbon.

[0150] The biodegradation process is presented in Table 9 below as the average percentage of biodegradation during incubation at 20, 40, 80, and 120 days.

[0151] Table 9: Percentage of biodegradation of reference and test materials .

[0152]

[0153] In summary, it is related to cellulose, polyvinyl acetate, and partially hydrolyzed polyvinyl acetate (KURARAY POVAL). ™ Compared to polyvinyl alcohol (LM10), Examples 1 and 2 of this invention each exhibit superior compostability. The binder compositions of this invention (and particularly IE1 and IE2) have DtCO2 values ​​greater than 90% after 120 days (IE1 107.2%, IE2 92.9%), as shown in Table 9.

[0154] It is particularly desirable that this disclosure is not limited to the embodiments and descriptions contained herein, but includes modifications of those embodiments, including portions of embodiments appearing within the scope of the following claims and combinations of elements of different embodiments.

Claims

1. An adhesive composition comprising: a reaction product comprising (A) a polyester polyol component comprising (i) a dicarboxylic acid, (ii) a C3-C6 diol, (iii) a dihydric alcohol; 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 one of claims 1-2, wherein the C3-C6 diol is butanediol.

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

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

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

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

8. The adhesive composition of any one 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 one of claims 1-8, comprising: (A) 70 to 90 weight percent of the polyester polyol component; and (B) 10 to 30 weight percent of the aliphatic isocyanate.

10. The adhesive composition of any one 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, methyl ethyl ketone, acetone, methyl butyl ketone, water, and combinations thereof.

12. The adhesive composition of any one of claims 1 to 10, wherein the adhesive composition has a Dtco2 value 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 adhesive layer being 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 dihydric alcohol; and (B) an aliphatic isocyanate.

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

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