EP4658699A1

EP4658699A1 - A recyclable, compostable adhesive

Info

Publication number: EP4658699A1
Application number: EP24705291.3A
Authority: EP
Inventors: Juan Carlos CASARRUBIAS; Mateus Batista Torres CIPRO; Gang Lu; Jorge Caminero GOMES; Elkin David CARDONA JIMENEZ; Maria Cristina HERRERA GARCIA; Juvenal GONZALEZ
Original assignee: Dow Quimica de Colombia SA; Dow Quimica Mexicana SA de CV; Dow Global Technologies LLC
Current assignee: Dow Quimica de Colombia SA; Dow Quimica Mexicana SA de CV; Dow Global Technologies LLC
Priority date: 2023-01-30
Filing date: 2024-01-08
Publication date: 2025-12-10
Also published as: MX2025008636A; JP2026505165A; WO2024163129A1; KR20250159640A; CN120659821A

Abstract

A laminate produced using a solventless laminating adhesive comprising an isocyanate and a polyol component having a recyclability property of 25% is disclosed. The isocyanate component can comprise from 50 to 70 wt.% aromatic isocyanate. The isocyanate component can comprise from 0 to 50 wt.% polyether polyol. The isocyanate component can comprise from 0 to 7 wt.% natural oil polyol. The isocyanate component can comprise 50 to 70 wt.% aromatic isocyanate, 0 to 50 wt.% polyether polyol, and 0 to 7 wt.% natural oil polyol. The polyol component can comprise a natural oil polyol. A laminate produced using a solventless laminating adhesive comprising an isocyanate component and a polyol component wherein the laminate disintegrates during composting such that: (1) plastic residue is not easily distinguishable from other organic materials, (2) the polymeric molecule is chemically transformed into biomass and other products (3) the compost obtained allows proper plant growth and (4) the compost obtained excludes high levels of metals is disclosed. The isocyanate component can comprise from 50 to 70 wt.% aromatic isocyanate. The isocyanate component can comprise from 0 to 50 wt.% polyether polyol. The isocyanate component can comprise from 0 to 7 wt.% natural oil polyol. The isocyanate component can comprise 50 to 70 wt.% aromatic isocyanate, 0 to 50 wt.% polyether polyol, and 0 to 7 wt.% natural oil polyol. The polyol component can comprise a natural oil polyol.

Description

A RECYCLABLE, COMPOSTABLE ADHESIVE FIELD

The current disclosure relates to an adhesive. More particularly the current disclosure relates to a solventless adhesive. Even more particularly the current disclosure relates to a solventless adhesive that is recyclable and compostable.

INTRODUCTION

Adhesive compositions are useful for a wide variety of purposes. For instance, some adhesives are used to adhere two or more film layers of substrates together thereby forming composite films, i.e., laminates comprising the two or more film layers. Example of substrates typically include polyethylenes, polypropylenes, polyesters, polyamides, metals, papers, or cellophane and the like. The use of adhesives in different laminating end-use applications is generally known. For example, adhesives, are generally applied between laminating films, can be used in the manufacture of film/film and film/foil laminates used in the flexible packaging industry for packaging of foodstuffs, pharmaceuticals, and industrial consumables, especially for food packaging. Laminating adhesives can be classified generally into three categories: (1) solvent-based laminating adhesives, (2) solventless laminating adhesives, and (3) water-based laminating adhesives. The performance of an adhesive varies by category and by the application in which the adhesive is applied.

Within the category of solventless laminating adhesives, there are many varieties; and one particular variety includes multi-component laminating adhesives; and more specifically a two-component adhesive. Typically, a two-component laminating adhesive includes a first component comprising an isocyanate and/or a prepolymer and a second component comprising one or more polyols. A prepolymer can be obtained by the reaction of a polyisocyanate with a polyether polyol and/or polyester polyol. The second component comprises polyether polyols and/or polyester polyols. Each component can optionally include one or more additives.

The two components (i.e., the isocyanate and polyol components) of the adhesive composition are combined in a predetermined ratio, thereby forming an adhesive composition. The adhesive composition is then applied on a film/foil substrate. Another film/foil substrate is then brought into contact with the other substrate, forming a curable laminate structure. The laminate structure is cured to bond the two substrates together.

Solventless adhesives are generally more environmentally friendly due to the lack of potentially polluting organic solvents, but they are usually not recyclable or compostable. Monosubstrate solutions such as 100% polyethylene adhesives can work but are not fit for all situations. This is especially true as composting laminates has become more popular and recyclable adhesives are not always compostable. A need thus exists for an adhesive that is both recyclable and compostable.

SUMMARY OF DISCLOSURE

A laminate produced using a solventless laminating adhesive comprising an isocyanate and a polyol component having a recyclability property of 25% is disclosed. The isocyanate component can comprise from 50 to 70 wt.% aromatic isocyanate based on the weight of the isocyanate component. The isocyanate component can comprise from 0 to 50 wt.% polyether polyol, based on the weight of the isocyanate component. The isocyanate component can comprise from 0 to 7 wt.% natural oil polyol based on the weight of the isocyanate component. The isocyanate component can comprise 50 to 70 wt.% aromatic isocyanate, 0 to 50 wt.% polyether polyol, and 0 to 7 wt.% natural oil polyol, based on the weight of the isocyanate component. The polyol component can comprise a natural oil polyol.

A laminate produced using a solventless laminating adhesive comprising an isocyanate component and a polyol component wherein the laminate disintegrates during composting such that: (1) plastic residue is not easily distinguishable from other organic materials, (2) the polymeric molecule is chemically transformed into biomass and other products (3) the compost obtained allows proper plant growth and (4) the compost obtained excludes high levels of metals is disclosed. The isocyanate component can comprise from 50 to 70 wt.% aromatic isocyanate based on the weight of the isocyanate component. The isocyanate component can comprise from 0 to 50 wt.% polyether polyol, based on the weight of the isocyanate component. The isocyanate component can comprise from 0 to 7 wt.% natural oil polyol based on the weight of the isocyanate component. The isocyanate component can comprise 50 to 70 wt.% aromatic isocyanate, 0 to 50 wt.% polyether polyol, and 0 to 7 wt.% natural oil polyol, based on the weight of the isocyanate component. The polyol component can comprise a natural oil polyol.

DETAILED DESCRIPTION

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.

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 to 7 above includes subranges 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6; etc.).

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 the composition.

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 or abbreviated as "NCO". 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 diisocyanate and an isocyanate that has three isocyanate groups is a triisocyanate, etc.

A "polyisocyanate" is a molecule that contains at least two isocyanate groups.

As used herein, the term "polymer" means 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), and the term copolymer or interpolymer. Trace amounts of impurities (for example, catalyst residues) may be incorporated into and/or within the polymer. A polymer may be a single polymer, a polymer blend, or a polymer mixture, including mixtures of polymers that are formed in situ during polymerization.

As used herein, the term "copolymer" means any polymer having two or more monomers.

A "polyol" is an organic compound containing multiple hydroxyl (OH) groups. In other words, a polyol contains at least two OH groups. Nonlimiting examples of suitable polyols include diols having two OH groups, triols having three OH groups, and tetraols having four OH groups.

As used herein, the term "polyethylene" means a polymer comprising a majority amount (>50 mol %) of units which have been derived from ethylene monomer.

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

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

A "polyester polyol" is a compound that contains a polyester and a polyol in the backbone structure of the compound.

A "polyether polyol" is a compound that contains a polyether and a polyol in the backbone structure of the compound.

"Recyclable" or "recyclability" herein, means mechanical recyclable or recyclability; and means the film article with a waterborne olefin-based coating is mechanically re-processable to generate another subsequent recycled article having a desirable performance and desirable properties.

"Recylability property", as used herein, is a measure of the change in performance between a second article produced from material recycled from a first article compared to a third article made from non-recycled material. For example an article made from recycled material that has a 50% decrease in performance in tear, gloss, haze and other properties when compared to an article made from non-recycled material would have a 50% recyclability property.

"Composting", as used herein, means turning a material with or without human intervention into a soil like material. "Compostable" as used herein means a substance is amenable to composting.

"Biomass" as used herein means organic material.

Laminate Produced Using A Solventless Laminate Adhesive

A laminate produced using a solventless laminate adhesive is disclosed. The solventless laminate adhesive can have an isocyanate component and a polyol component. The laminate can have a recyclability property equal to or less than 25%. The laminate can have a recyclability property from 0 to 25%. All individual values and subranges are disclosed. For example, the laminate can have a recyclability property from a lower limit of 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, or 22% to an upper limit of 25, 23, 21, 19, 17, 15, 13, 11, 9, 7, 5, or 3%. The laminate can be compostable. The laminate can disintegrate such that plastic residue is not easily distinguishable from other organic materials. The laminate can disintegrate such that at least 50% of the laminate is not easily distinguishable as plastic residue from other organic materials. The laminate can disintegrate such that from 50 to 100% of the laminate is not easily distinguishable as plastic residue from other organic materials. All individual values and subranges are disclosed. For example the laminate can disintegrate such that from an upper limit of 100, 95, 90, 85, 80, 75, 70, 65, 60, or 55% to a lower limit of 55, 60, 65, 70, 75, 80, 85, 90, or 95% of the laminate is not easily distinguishable as plastic residue from other organic materials.

The laminate can disintegrate such that the polymeric molecule is chemically transformed into biomass and other products. The laminate can disintegrate such that the polymeric molecule is chemically transformed into biomass and other products when compared to a reference material. The laminate can disintegrate such that at least 50% of the laminate is chemically transformed into biomass and other products when compared to a reference material. The laminate can disintegrate such that from 50 to 100% of the laminate is chemically transformed into biomass and other products when compared to a reference material. All individual values and subranges are disclosed. For example, the laminate can disintegrate such that from an upper limit of 100, 95, 90, 85, 80, 75, 70, 65, 60, or 55% to a lower limit of 55, 60, 65, 70, 75, 80, 85, 90, or 95% of the laminate is chemically transformed into biomass and other products when compared to a reference material. The laminate can disintegrate such that compost obtained allows proper plant growth. The laminate can disintegrate such that plants germinate in the presence of disintegrated laminate. The laminate can disintegrate such that plants germinate in the presence of soil comprising at least 10% disintegrated laminate. The laminate can disintegrate such that plants germinate in the presence of soil comprising from 10 to 90% disintegrated laminate. All internal values and subranges are disclosed. For example the laminate can disintegrate such that plants germinate in the presence of soil comprising at a high end of 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, or 15% disintegrated laminate to a low end of 10, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% disintegrated laminate.

The laminate can disintegrate such that at least 1% of seeds germinate in the presence of disintegrated laminate. The laminate can disintegrate such that from 1 to 90% of seeds germinate in disintegrated laminate. All internal values and subranges are disclosed. For example, the laminate can disintegrate such that at a high end 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5%, of seeds to a low end of 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% of seeds germinate in disintegrated laminate.

The laminate can disintegrate such that at least 1% of seeds germinate in the presence of soil comprising at least 10% disintegrated laminate. The laminate can disintegrate such that from 1 to 90% of seeds germinate in the presence of soil comprising from 10 to 90% disintegrated laminate. All internal values and subranges of both ranges are disclosed. For example, the laminate can disintegrate such that at a high end 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 5, or 1% of seeds germinate to a low end of 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% of seeds germinate in soil comprising at a high end of 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, or 15% disintegrated laminate to a low end of 10, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% disintegrated laminate.

The laminate can disintegrate such that at least 1% of seeds germinate in the presence of disintegrated laminate when compared to a blank. The laminate can disintegrate such that from 1 to 90% of seeds germinate in disintegrated laminate when compared to a blank. All internal values and subranges are disclosed. For example, the laminate can disintegrate such that at a high end 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5%, of seeds to a low end of 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% of seeds germinate in disintegrated laminate when compared to a blank.

The laminate can disintegrate such that at least 1% of seeds germinate in the presence of soil comprising at least 10% disintegrated laminate when compared to a blank. The laminate can disintegrate such that from 1 to 90% of seeds germinate in the presence of soil comprising from 10 to 90% disintegrated laminate when compared to a blank. All internal values and subranges of both ranges are disclosed. For example, the laminate can disintegrate such that at a high end 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 5, or 1% of seeds germinate when compared to a blank to a low end of 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% of seeds germinate when compared to a blank in soil comprising at a high end of 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, or 15% disintegrated laminate to a low end of 10, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% disintegrated laminate.

The laminate can disintegrate such that plants grown in the presence of disintegrated laminate generate at least 95% biomass relative to a blank. The laminate can disintegrate such that plants grown in the presence of disintegrated laminate generate from .1 to 95% biomass relative to a blank. All internal values and subranges are disclosed. For example, the laminate can disintegrate such that plants grown in the presence of disintegrated laminate generate at least at a high end 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5% biomass relative to a blank to a low end of .1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90% biomass relative to a blank.

The laminate can disintegrate such that plants grown in the presence of disintegrated laminate generate at least 95% biomass, relative to a blank, in soil comprising at least 10% disintegrated laminate. All internal values and subranges are disclosed. For example, the laminate can disintegrate such that plants grown in the presence of disintegrated laminate generate at least at a high end 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5% biomass relative to a blank to a low end of .1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90% biomass relative to a blank in soil comprising at a high end of 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, or 15% disintegrated laminate to a low end of 10, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85% disintegrated laminate. The laminate can disintegrate such that the compost obtained excludes high levels of metals. The laminate can disintegrate such that the compost obtained excludes high levels of cadmium, chrome, copper, lead, nickel, zinc, mercury, and arsenic. The laminate can disintegrate such that the compost obtained has less than 0.74 mg/kg on a dry basis of cadmium. The laminate can disintegrate such that the compost obtained has less than 10.24 mg/kg on a dry basis of chrome. The laminate can disintegrate such that the compost obtained has less than 13.84 mg/kg on a dry basis of copper. The laminate can disintegrate such that the compost obtained has less than 9.41 mg/kg on a dry basis of lead. The laminate can disintegrate such that the compost obtained has less than 5.45 mg/kg on a dry basis of nickel. The laminate can disintegrate such that the compost obtained has less than 23.43 mg/kg on dry basis of zinc. The laminate can disintegrate such that the compost obtained has less than 0.08 mg/kg on a dry basis of mercury. The laminate can disintegrate such that the compost obtained has less than 0.13 mg/kg on a dry basis of Arsenic.

The laminate can disintegrate during composting such that: (1) plastic residue is not easily distinguishable from other organic materials, (2) the polymeric molecule is chemically transformed into biomass and other products (3) the compost obtained allows proper plant growth, and (4) the compost obtained excludes high levels of metals.

The polyol component can comprise 60 to 90 wt.% based on the weight of the laminating adhesive. All individual values and subranges are included. The polyol component, for example, can comprise from 65 to 85% based on the weight of the laminating adhesive.

Isocyanate Component

The isocyanate component can comprise 50 to 70 wt.% aromatic isocyanate, based on the weight of the isocyanate component. All internal values and subranges are included. For example, the isocyanate component can comprise 55 to 65 wt.% aromatic isocyanate or 60 to 70 wt.% aromatic isocyanate based on the weight of the isocyanate component. The aromatic-based isocyanate in the isocyanate component can be, for example, an isocyanate monomer, a polyisocyanate (e.g. dimers, trimers, etc.) an isocyanate prepolymer, and mixtures of two or more of the preceding. A "polyisocyanate" is any compound that contains two or more isocyanate groups. The aromatic-based isocyanates useful in the present disclosure can include, for example, one or more polyisocyanate compounds including, but are not limited to, for example 1,3- and 1,4-phenylene diisocyanate; 1,5-naphthylene diisocyanate; 2,4'-diphenylmethane diisocyanate (2,4'-MDI); 4,4'-diphenylmethane diisocyanate (4,4'-MDI); 3,3'-dimethyl-4,4'- biphenyldiisocyanate (TODI) and isomers thereof; polymeric isocyanates; and mixtures of two or more thereof.

Exemplary of some of the commercial aromatic-based components useful in the present disclosure can include, for example, ISONATE™ 125 M, ADCOTTE™ L76-204, COREACTANT CT™, , available from The Dow Chemical Company; DESMODUR™ E 2200/76, available from The Covestro Company; and mixtures thereof.

The aromatic isocyanate can be at least 50% 4-4' -diphenylmethane diisocyanate. The aromatic isocyanate can be at least 90% 4-4'-diphenylmethane diisocyanate. The aromatic isocyanate can be from 50 to 100% 4-4' -diphenylmethane diisocyanate. All internal values and subranges are disclosed. For example the aromatic isocyanate can be at lest 55 to 95% 4-4'- diphenylmethane diisocyanate.

The isocyanate component can comprise 0 to 50 wt.% polyether polyol, based on the weight of the isocyanate component. All internal values and subranges are disclosed. For example, the isocyanate component can comprise from 5 to 40 wt.% or from 10 to 35 wt.% polyether polyol based on the weight of the isocyanate component. Suitable polyether polyols include but not limited to polypropylene glycols, polytetramethylene ether glycols, polybutylene oxide based polyols, or mixtures and copolymers of them. Commercial polyether polyols that can be used in the current disclosure include but are not limited to, Voranol ™ 220-056N Polyol, Voranol ™ 232-034N Polyol, and Voranol ™ 220-110N Polyol, all of which are available from DOW™ chemical.

The isocyanate component can comprise O to 7 wt.% natural oil polyol. All internal values and subranges are disclosed. For example, the isocyanate component can comprise 1 to 6 wt.% natural oil polyol. Suitable natural oil polyols include but are not limited to, castor oil, corn oil, and soybean oil. Polyol Component

The polyol component can comprise any natural oil polyol including but not limited to castor oil, corn oil, and soybean oil.

Solventless Adhesive Additional Components and Production

The adhesive composition of the present disclosure can include one or more additional optional conventional ingredients or additives including but not limited to, catalysts, tackifiers, adhesion promoters, antioxidants, fillers, colorants, pigments, surfactants, solvents, polymers (including, for example, thermoplastic resins other than those discussed herein above), dehydrating agents (including, for example, silanes), benzoyl chloride, other polyols (including, for example, fatty polyols), ultraviolet indicators, and combinations of two or more of these.

The adhesive composition may include, for example, an adhesion promoter. Non-limiting examples of suitable adhesion promoters include coupling agents such as a silane coupling agent, a titanate coupling agent, and an aluminate coupling agent; epoxy resin, phosphoric acid, polyphosporic acid, and phosphate esters.

Examples of the silane coupling agent useful in the present disclosure include, but are not limited to, aminosilanes such as y-aminopropyltriethoxysilane, y-aminopropyl-trimethoxysilane, N-|3(aminoethyl)-y-aminopropyltrimethoxysilane, N-P(aminoethyl)-y-aminopropyltrimethyl dimethoxysilane, and N-phenyl-y-aminopropyltrimethoxysilane; epoxysilanes such as |3-(3,4- epoxycyclohexyl)-ethyltrimethoxysilane, y-glycidoxypropyl-trimethoxysilane, and y-glycidoxypropyltriethoxysilane; vinylsilanes such as vinyl tris(P-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, and y-methacryloxypropyltrimethoxysilane; hexamethyldisilazane; y-mercaptopropyl-trimethoxysilane; and mixtures thereof.

Examples of the titanate coupling agent useful in the present disclosure include, but are not limited to, tetraisopropoxy titanium, tetra-n-butoxy titanium, butyl titanate dimer, tetrastearyl titanate, titanium acetylacetonate, titanium lactate, tetraoctyleneglycol titanate, titanium lactate, tetra stearoxy titanium; and mixtures thereof.

Examples of the epoxy resin useful in the present disclosure include, but are not limited to, a variety of readily available epoxy resins such as bisphenol A-epichlorohydrin (epi-bis) type epoxy resin, novolak type epoxy resin, p-methylepichlorohydrin type epoxy resin, cyclic oxirane type epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, polyglycol ether type epoxy resin, glycol ether type epoxy resin, epoxidation fatty acid ester type epoxy resin, polycarboxylic acid ester type epoxy resin, aminoglycidyl type epoxy resin, resorcin type epoxy resin; and mixtures thereof.

The adhesion promoter can be a phosphate ester compound or an epoxy silane ((3- glycidyloxypropyl)-trimethoxysilane). Phosphoric acid can be incorporated in the polyol component while epoxy silane can be incorporated in the isocyanate component. Both epoxy silane and phosphoric acid can be incorporated in the polyol component.

It is contemplated that two components, an isocyanate component and a polyol component, are employed in the present disclosure. It is also contemplated that the isocyanate component and the polyol component of the disclosed adhesive composition can be made separately and, if desired, stored until it is desired to use the adhesive composition. The process of producing the adhesive composition includes mixing the isocyanate and polyol components described above to form a curable adhesive composition. In some embodiments, both the isocyanate component and the polyol component are each liquid at 25 °C. When it is desired to use the adhesive composition, the isocyanate component and the polyol component are brought into contact with each other and mixed together, typically at a stoichiometric ratio (NCO/OH) between 1 and 2.5. It is contemplated that when these two components are brought into contact, a curing reaction begins in which the isocyanate groups react with the hydroxyl groups to form urethane links. The adhesive composition formed by bringing the two components into contact can be referred to as a "curable mixture."

To form the adhesive composition, mixing of the two components may take place at any suitable time in the process of forming the adhesive composition and applying the adhesive to a substrate, such as before, during, or as a result of the application process. All of the present steps may be carried out under ambient, room temperature conditions. As desired, heating or cooling may be employed. The mixing can be carried out using a suitable conventional mixer, such as using an electrically, pneumatically, or an otherwise powered mechanical mixer. The process for preparing the solvent-based adhesive composition of the present disclosure includes, for example, the steps of (1) providing the isocyanate component; (2) providing the polyol component; (3) mixing the two components to form a resin mixture.

Adhesive Use Laminate Production

The adhesive composition of the present disclosure is useful for bonding substrates together; and the adhesive composition can be used on a wide variety of a single suitable substrate or a plurality of suitable substrates. The substrates may be similar materials or dissimilar materials. For example, the substrate may be selected from high, low or medium density plastics (e.g., of a type selected from polystyrene, polyethylene, ABS, polyurethane, polyethylene terephthalate, polybutylene terephthalate, polypropylene, polyphenylene, polycarbonate, polyacrylate, polyvinyl chloride, polysulfone, and mixtures thereof), paper, wood and reconstituted wood products, polymer coated substrates, wax coated paperboard, cardboard, particle board, textiles, leather, and metal (e.g., aluminum, ferrous as well as other non-ferrous), metallized plastics (e.g., metallized plastic film) or the like.

Wet and dry bond lamination of a plurality of substrate layers is possible. The adhesive composition can be applied to desired substrates using conventional application techniques such as rotogravure printing, flexographic printing, conventional or airless spray, roll coating, brush coating, wire wound rod coating, knife coating, or coating processes such as curtain-, flood-, bell-, disc-, and dip-coating processes. Coating a substrate with the adhesive composition may be done over the entire surface of the substrate or to a portion of the substrate's surface, such as along an edge, or at intermittent locations.

TESTING METHODS

Recyclability

Recyclability is tested using guidelines proposed by the Association of Plastic Recyclers (APR). 50% recycled compounded mixed pellets from PE/PE film laminated with each adhesive are mixed with 50% virgin pe then blown and tested for thickness, dart impact, surface impression and visually inspected. Tear, tensile strength, and secant are also tested in both the machine and cross direction. The results of these tests are compared with a film made of 100% virgin material.

Bond Strength Measurement

Laminate samples are cut to 15mm wide strips and pulled on a THWING ALBERT™ QC-3A peel tester equipped with a 50N loading cell at a rate of 4 inch/min. When the two films in the laminate separate, the average of the force during the pull is recorded. If one of the films stretches or breaks the maximum force or force at break is recorded. The values are the average of three separate sample strips. The initial or green bonds are tested as soon as possible after the laminate is made.

T-Peel (90°) Bonding Strength (Hand Assisted T-Peel) at 120 °C

After curing, laminated films are cut into 15 mm width test strip samples forT-peel testing in an Instron 5965 U 5974 machine with a crosshead speed of 250 millimeters per minute (mm/min). Three test strips are then tested in a warm oven at 120 °C and an average value of the three strips tested is recorded. During the testing, the tail of the strip is pulled slightly by finger to ensure the tail of the strip remains at 90° degrees toward the peeling direction. The results of the bonding strength test are measured in units of N/15 mm.

Tear Test

Sixteen 6x6 inch square samples are prepared and cut into 3x3 inch squares. These are mounted in clamps parallel to the floor. Film thickness of each 3x3 inch square is measured using a caliper-type gauge measure. The samples are then notched and pulled vertically and the CD and MD tear measured. Tensile Test

A 6x6 inch sample square is cut into six 1 inch wide strips. These strips are mounted into tensile grippers and pulled at a rate of 50mm/min until break separately in the MD and CD direction.

Haze Test

A BYK Hazegard-1 is used to measure the haze on a 6x6 inch sample square in compliance with ASTMD1003

Dart Test

Sample film is struck at 3.3m/s with a standard Instron dart probe polished to a mirror finish. Peak force, peak energy, displacement and total energy are all measured in accordance with ASTM 7192.

Compostability Testing

The sample is tested to see if: (1) it fragments during composting, (2) the polymeric molecule is chemically transformed into biomass and other products, (3) plants can grow properly with the compost obtained, and (4) if high levels of metals and other harmful components are introduced. Fragmentation is tested using ISO 20200:2015. Biodegradation is tested using ISO 14855-1:2012. Growth of plants in generated compost is tested by having plants grow in the compost generated and measuring the germination and germinated biomass relative to a blank. The test is explained in more detail in NMX-E-273-NYCE-2019 Appendix A OECD Test No. 208. The NMX is published by the official federal diary of Mexico and can be found at

The presence of cadmium, chrome, copper and the other metals listed below are tested for using NOM-004-SEMARNAT-2002. The NYCE norms are set by the Mexican government and can be found at https://nvce.ora. mx/catalosodeestandaresnvce/producto/nmx“e"273-nvce-20:19“

EXAMPLES

Materials used are listed in table 1 below. Table 1: Materials

Adhesive Production

The adhesive formulations shown in table 2 were produced by heating MDI Isocyanate until 60°C is reached at which time the polyol component is added. If two or three polyol ingredients are used they can be blended together before addition or added in steps. During polyol addition the temperature is kept under 70°C until the desired NCO% is reached. NCO%s between 11 and 19 are preferable. Table 2: NCO Terminated Prepolymer and OH-Terminated correactants (CR) composition

Table 3: Composition of Inventive and Comparative Samples

Adhesive was applied to laminate using a laminating machine designed for solventfree adhesives applications as LABO COMBI™ 400 laminator commercially available from Nordeccanica Group. The adhesive was applied onto a first substrate layer and the first substrate layer nipped to a second substrate layer. Coating weight during this process is kept between 1.3 to 4.8 g/m². During the nipping process, a metallic cylinder heated from 45 °C up to 90°C is in contact with the non coated side of the first substrate layer and a rubber roller is in contact with the noncoated side of the second substrate layer. The produced laminate structure is then rewound. In table 4 below first the value for each property measured is presented than the percent difference between this value and the value measured for a sample composed of pellets made from 100% virgin polyethylene.

Table 4.1: Recyclability Results in comparison to "Comparative 01" Table 4.2: Recyclability Results in comparison to "Comparative 02"

The inventive samples were mixed together and tested for compostability . One-hundred percent of the sample disintegrated and the rate of biodegradeability was 105.2% when compared to reference material. Results from plants grown in compost generated from 5 laminates using the inventive compositions is shown in table 5 while results of heavy metal testing are shown in table 6.

Table 5: Results From Plants Grown In Compost

Table 6:

Claims

What is claimed is:

1. A laminate produced using a solventless laminating adhesive comprising: a. an isocyanate component comprising: i. 50 to 70 wt.% aromatic isocyanate, based on the weight of the isocyanate component ii. 0 to 50 wt.% polyether polyol, based on the weight of the isocyanate component iii. 0 to 7 wt.% natural oil polyol, based on the weight of the isocyanate component b. a polyol component comprising a natural oil polyol wherein the laminate has a recyclability property of equal to or less than 25%.

2. The solventless laminating adhesive of claim 1 wherein the polyol component comprises 60 to 90 wt.% based on the wight of the laminating adhesive.

3. The solventless laminating adhesive of claim 1 wherein the aromatic isocyanate is at least 50% 4-4' -diphenylmethane diisocyanate.

4. The solventless laminating adhesive of claim 1 wherein the aromatic isocyanate is at least 90% 4-4' -diphenylmethane diisocyanate.

5. The laminate adhesive of claim 1 containing no polyester.

6. A laminate produced using a solventless laminating adhesive comprising: a. an isocyanate component comprising: i. 50 to 70 wt.% aromatic isocyanate, based on the weight of the isocyanate component ii. 0 to 50 wt.% polyether polyol, based on the weight of the isocyanate component iii. 0 to 7 wt.% natural oil polyol, based on the weight of the isocyanate component b. a polyol component comprising a natural oil polyol wherein the laminate disintegrates during composting such that: (1) plastic residue is not easily distinguishable from other organic materials, (2) the polymeric molecule is chemically transformed into biomass and other products (3) the compost obtained allows proper plant growth, and (4) the compost obtained excludes high levels of metals.

7. The solventless laminating adhesive of claim 6 wherein the polyol component comprises 60 to 90 wt.% based on the wight of the laminating adhesive.

8. The solventless laminating adhesive of claim 6 wherein the aromatic isocyanate is at least 50% 4-4' -diphenylmethane diisocyanate.

9. The solventless laminating adhesive of claim 6 wherein the aromatic isocyanate is at least 90% 4-4' -diphenylmethane diisocyanate.

10. The laminate adhesive of claim 6 containing no polyester.