solvent-based laminating adhesive

Abstract

A crystalline polycarbonate-based two-component solvent-based polyurethane adhesive composition for producing adhesive laminate structures, comprising: (a) at least one isocyanate component; and (b) at least one isocyanate-reactive component comprising the reaction product of (i) at least one crystalline polycarbonate diol compound, (ii) at least one acrylic polymer compound, and (iii) at least one solvent, as well as a process for preparing the adhesive composition.

Description

[Technical Field]

[0001] The present invention relates to solvent-based lamination adhesive compositions and processes for preparing such lamination adhesive compositions. [Background technology]

[0002] Laminating adhesives are used to bond different substrates together. A common use of such bonding substrates is in flexible food packaging applications. Laminating adhesives are typically applied to the surfaces of two polymer substrate layers to form a bond between the two substrate layers. The adhesive forms a bond between the substrate layers, providing a strong bond between the two substrate layers. The adhesively bonded substrate structure helps keep the packaging structure intact and the food inside the packaging structure safe and secure. Increasing demand in the flexible food packaging industry relates to laminating adhesives with good gas barrier properties that reduce oxygen permeability through the layered structure of flexible food packaging. Laminating adhesives used to produce layered food packaging structures with reduced oxygen permeability could potentially simplify the packaging structure, reduce costs at the time of use, and make the food packaging recyclable. Therefore, it is desirable to provide laminating adhesives with improved oxygen barrier performance, such as adhesives that exhibit low oxygen permeability compared to standard adhesives. In particular, it is desirable to provide laminating adhesives based on crystalline polycarbonate compounds so that the adhesive has gas barrier effects / properties. Summary of the Invention

[0003] It is an object of the present invention to provide a lamination adhesive useful in flexible packaging applications, which has enhanced oxygen barrier performance compared to standard adhesives, and a process for producing such a lamination adhesive.

[0004] In one embodiment, the present invention is directed to a two-component solvent-based polyurethane laminating adhesive composition, the adhesive composition being based on crystalline polycarbonate, the adhesive composition being useful for producing multi-layer laminate structures. The adhesive composition includes, for example, (a) at least one isocyanate component, (b) at least one isocyanate-reactive component including the reaction product of (bi) at least one crystalline polycarbonate diol compound, (bii) at least one flow modifier such as an acrylic polymer compound, (biii) optional additives, if desired, and (c) at least one solvent.

[0005] In another embodiment, the present invention is directed to a process for preparing the adhesive composition described above.

[0006] In yet another embodiment, the present invention is directed to a multi-layer laminate product comprising: (A) at least a first layer; (B) at least a second layer; and (C) at least one layer of the adhesive composition described above disposed between the first and second layers, wherein the adhesive composition is cured to bond the first layer to the second layer.

[0007] In yet another embodiment, the present invention is directed to a process for producing the multi-layer laminate product described above.

[0008] In still yet another embodiment, the present invention is directed to a packaging product manufactured using the multi-layer laminate product described above. DETAILED DESCRIPTION OF THE INVENTION

[0009] As used throughout this specification, the following abbreviations have the following meanings, unless the context clearly dictates otherwise: "<" means "less than," ">" means "greater than," "≦" means "less than or equal to," "≧" means "greater than or equal to," "@" means "at," μm = micrometer, g = gram, mg = milligram, L = liter, g / cc = grams per cubic centimeter, mL = milliliter, g / mL = grams per milliliter, g / mol = grams per mole, g / m 2 = grams per square metre, ppm = parts per million, ppmw = parts per million by weight, rpm = revolutions per minute, m = metres, mm = millimetres, cm = centimetres, cm / min = centimetres per minute, min = minutes, s = seconds, hr = hours, °C = degrees Celsius, N = Newtons, mmHg = millimetres of mercury, psig = pounds per square inch, ccO2 / m 2 / day = cubic centimeters of oxygen per [square meter / day], N / 15mm = Newtons per 15 millimeters, kPa = kilopascals, % = percent, vol% = volume percent, and wt% = weight percent.

[0010] Unless otherwise specified, all percentages, parts, ratios, and other amounts are defined by weight. For example, all percentages set forth herein are weight percentages (wt %) unless otherwise indicated.

[0011] Temperatures are in degrees Celsius (°C), and "ambient temperature" and / or "room temperature" means a temperature between 20°C and 25°C unless otherwise specified.

[0012] The present invention is directed to a novel two-component solvent-based polyurethane adhesive composition, which is based on crystalline polycarbonate and is useful for producing adhesive laminate structures. The adhesive composition includes, for example, (a) at least one isocyanate component; and (b) at least one isocyanate-reactive component comprising the reaction product of (bi) at least one crystalline polycarbonate diol compound, (bii) at least one acrylic polymer compound, and (biii) at least one solvent.

[0013] Generally, preparing a two-part laminating adhesive composition involves providing a first part that includes component (a), an isocyanate component, and providing a second part that includes component (b), an isocyanate-reactive component, such as, for example, a polyol component, and then combining or mixing components (a) and (b) together to form the two-part adhesive system or composition.

[0014] The isocyanate component, component (a) of the present invention, can contain one or more isocyanate compounds. For example, the isocyanate compound can include aliphatic isocyanates, aromatic isocyanates, and mixtures thereof. An "aliphatic polyisocyanate" is an isocyanate that does not contain an aromatic ring. Examples of suitable aliphatic isocyanates useful in the present invention include hexamethylene diisocyanate (HDI), diisocyanatodicyclohexylmethane (HDI), and the like. 12 MDI), xylylene diisocyanate (XDI), 1,4- or 1,3-bis(isocyanatomethyl)cyclohexane (H6XDI), tetramethylxylylene diisocyanate, dimers, trimers, derivatives, and mixtures of two or more thereof.

[0015] Aromatic isocyanates useful in the present invention may include, for example, one or more polyisocyanate compounds, including, but not limited to, 1,3- and 1,4-phenylene diisocyanate, 1,5-naphthylene diisocyanate, 2,6-toluene diisocyanate (2,6-TDI), 2,4-toluene diisocyanate (2,4-TDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 4,4'-diphenylmethane diisocyanate (4,4'-MDI), polymeric isocyanates, and mixtures of two or more thereof.

[0016] In one preferred embodiment, the isocyanate component useful in the present invention can be XDI-based polyisocyanates, HDI-based polyisocyanates, MDI-based polyisocyanates, TDI-based polyisocyanates, and mixtures thereof.

[0017] Examples of some commercially available isocyanate components useful in the present invention include TAKENATE® D-110N and TAKENATE® D-120N (both available from Mitsui Chemicals), DESMODUR® N 3300, DESMODUR® Quix 175, and DESMODUR® E 2200 / 76 (all available from The Covestro Company), and ISONATE™ 125M, ADCOTE™ L76-204, COREACTANT CT, and CATALYST F (all available from The Dow Chemical Company), and mixtures thereof.

[0018] The isocyanate has an average functionality of greater than 2 isocyanate groups / molecule. In one embodiment, for example, the isocyanate may have an average functionality of 2.1 to 4.0.

[0019] Compounds having isocyanate groups, such as the isocyanate component (a) of the present invention, can also be characterized by the weight percent of isocyanate groups (NCO), based on the total weight of the compound. The weight percent of isocyanate groups is referred to as "NCO%" and is measured according to ASTM D2572-97. In one embodiment, the NCO content of component (a) is 7% or greater, and in another embodiment, 10% or greater. In yet another embodiment, the NCO content of component (a) is 30% or less, and in yet another embodiment, 25% or less.

[0020] The amount of isocyanate component used in the process of the present invention is, for example, from 2% to 40% by weight in one embodiment, from 3% to 30% by weight in another embodiment, and from 4% to 20% by weight in yet another embodiment.

[0021] The isocyanate-reactive component, component (b) (or B-side component) of the present invention, comprises an isocyanate-reactive composition that is the reaction product of (bi) a predetermined amount of at least one crystalline polycarbonate diol compound, (bii) a predetermined amount of at least one acrylic polymer compound, and (biii) a predetermined amount of at least one solvent. A blend or mixture of the above three components (bi)-(biii) forms the isocyanate-reactive component (b), which is mixed with the isocyanate component (a). A crystalline polycarbonate-based polyurethane adhesive composition for producing an adhesive laminate structure is formed by mixing component (a) with component (b).

[0022] Component (a) can be mixed with component (b) in a weight ratio of 4:100 to 30:100 in one embodiment, 5:100 to 25:100 in another embodiment, and 6:100 to 20:100 in yet another embodiment.

[0023] Crystalline polycarbonate diols are compounds having a structure of carbonate units and hydroxyl end groups, and are solid over a temperature range including the range of 10° C. to 40° C. Examples of suitable crystalline polycarbonate diols useful in the present invention include, but are not limited to, poly(hexanediol-carbonate), poly(butanediol-carbonate), and mixtures of two or more thereof.

[0024] In one preferred embodiment, the crystalline polycarbonate diol has a melting temperature of 35° C. to 60° C. and a molecular weight of 500 g / mol to 3,500 g / mol.

[0025] Some examples of commercially available crystalline polycarbonate diol compounds useful in the present invention include, for example, ETERNACOLL® UH-100, ETERNACOLL® UH-200, and ETERNACOLL® UH-300 available from UBE Industries, Inc.

[0026] The amount of crystalline polycarbonate diol compound used to make component (b), the isocyanate-reactive co-reactant, of the process of the present invention is, for example, 10% to 50% by weight in one embodiment, and 15% to 50% by weight in another embodiment. 45% by weight and in yet another embodiment, 20% to 40% by weight.

[0027] The at least one acrylic polymer compound, component (ii), useful in the present invention is a flow modifier or flow control agent typically used in powder coatings to control cratering and reduce orange peel characteristics. Flow control agents help control the interfacial and surface tension of the adhesive.

[0028] The flow control agent useful in the present invention can include one or more common flow control agents, such as low glass transition temperature acrylic resins, such as polylauryl acrylate, polybutyl acrylate, poly(2-ethylhexyl)acrylate, poly(ethyl acrylate-2-ethylhexyl acrylate), polylauryl methacrylate, acrylic copolymers made from two or more monomers (including methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, styrene, vinyl acetate, butadiene, etc.), and mixtures thereof. Other useful flow control agents can include silicon-containing polymers and fluorinated polymers, such as esters of polyethylene glycol or polypropylene glycol, and fluorinated fatty acids.

[0029] The amount of acrylic polymer used to make the isocyanate-reactive co-reactant, component (b) of the process of the present invention, is, for example, from 0.05% to 4% by weight in one embodiment, from 0.1% to 3% by weight in another embodiment, and from 0.2% to 2% by weight in yet another embodiment.

[0030] The at least one solvate, component (c) of the present invention, can comprise one or more compounds, including any conventional carrier solvent, such as, for example, ethyl acetate, methyl ethyl ketone, dioxolane, propyl acetate, toluene, and mixtures thereof. In one preferred embodiment, the solvate useful in the present invention can be ethyl acetate, methyl ethyl ketone, and mixtures thereof.

[0031] The amount of solvent compound used to make the isocyanate-reactive co-reactant, component (b) of the process of the present invention, is, for example, from 10% to 90% by weight in one embodiment, from 30% to 85% by weight in another embodiment, and from 50% to 80% by weight in yet another embodiment.

[0032] In some embodiments, the adhesive compositions of the present invention can include one or more optional additives, including, but not limited to, for example, tackifiers, catalytic plasticizers, rheology modifiers, adhesion promoters, antioxidants, fillers, colorants, surfactants, solvents, and combinations of two or more thereof.

[0033] The amount of optional components useful in the adhesive composition can be, for example, from 0% to 3% by weight in one embodiment, from 0% to 2% by weight in another embodiment, and from 0.01% to 1% by weight in yet another embodiment.

[0034] Generally, the process of making the laminating adhesive composition includes the steps of: (I) melting a crystalline polycarbonate diol at a temperature of 50°C to 70°C; (II) pouring the molten diol into a reactor, which is preheated to a temperature of 50°C to 60°C; (II) charging the reactor with a solvent and any other optional additives; (IV) mixing all the ingredients in the reactor by stirring until a uniformly mixed, completely clear solution is formed; and (V) removing the resulting completely clear solution from the reactor.

[0035] Multilayer laminate products can be formed containing layers of the solvent-based polyurethane adhesive composition based on crystalline polycarbonate of the present invention. Any number of layers can be used to form the laminate product. In one preferred embodiment, the laminate is formed by applying the adhesive composition to at least one of two substrate layers (e.g., the substrates can be made of the same material or different materials), combining the substrates together so that the adhesive composition is disposed as a layer between the surfaces of the two substrates, and then curing the adhesive composition to form a bonded layer between the two substrates. Typically, each of the two substrates can comprise, for example, two separate polymer films. As used herein, a "film" is any layered structure in which one dimension of the layered structure is 0.5 mm or less and the other two dimensions of the layered structure are both 1 cm or more. A "polymer film" is a film made from a polymer or a mixture of polymers. The composition of a polymer film is typically 80 weight percent or more of one or more polymers.

[0036] Suitable substrates used to form laminate structures include papers, woven and nonwoven fabrics, films such as polymeric films, metal coated (metallized) polymeric films, and combinations thereof. The substrates are layered to form the laminate structure using an adhesive composition according to the present invention that adheres one or more of the substrates together.

[0037] In a preferred embodiment, a multi-layer laminate product prepared using the adhesive composition of the present invention comprises (A) at least a first layer, (B) at least a second layer, and (C) at least one layer of adhesive composition disposed between the first and second layers, wherein the adhesive is cured to bond the first layer to the second layer.

[0038] In one general embodiment, a multilayer laminate product can be two or more film substrates or film layers combined together using an adhesive composition. In some embodiments, a laminate film structure is disclosed that includes a first film layer, a second film layer, and a barrier adhesive layer disposed between the first and second film layers. For example, in a preferred embodiment, a multilayer laminate product can be made from three layers, including a first film layer (or outer layer), a second film layer (or inner layer), and a tie layer that includes the adhesive composition and is disposed between the first and second layers.

[0039] The three-layer laminate product of the present invention can have a layered structure of A / B / A, where A represents the first and second layers of the same material, and B represents a bonding layer of an adhesive composition. Although three-layer laminate film products are referred to herein, the present invention includes multilayer laminate members with any number of film layers, provided that at least one layer of the multilayer film member is a bonding layer of an adhesive composition, and the bonding layer has suitable gas barrier properties. As previously mentioned, the structure of the multilayer film member can be A / B / A, where both layers, represented by A, are made from the same polymeric material, or the structure of the multilayer film member can be A / B / C, where C represents a film layer made from a different material than layer A. Or the structure of the multilayer film member can be any combination of A, B, and C layers, as would be apparent to one skilled in the art of making laminates.

[0040] The first layer of the laminate product of the present invention can be made from one or more materials including, for example, polyethylene, polypropylene, polyethylene terephthalate, polyamide, polystyrene, cycloolefin copolymer, polyvinyl chloride, styrene butadiene, etc. In one preferred embodiment, the first layer material useful in the present invention can be polypropylene, polyethylene, and combinations thereof. Some examples of commercially available materials useful in the first layer of the present invention include, for example, biaxially oriented polypropylene (available from FILMTECH, INC.) and polyethylene (available from Berry Plastics), and mixtures thereof. In another preferred embodiment, the first film layer can be made from polypropylene having a density of, for example, 0.89 g / cc to 0.92 g / cc.

[0041] The thickness of the first layer used in the laminate product of the present invention is, for example, 10 μm to 200 μm in one embodiment, 15 μm to 150 μm in another embodiment, and 20 μm to 125 μm in yet another embodiment.

[0042] As mentioned above, the second layer of the laminate product of the present invention can be made from the same material as the first layer, which has the advantage of being more easily recyclable. In another embodiment, the second layer can be made from one or more materials different from the first layer.

[0043] When the second layer of the laminate product is made of a polymer different from the first layer, the second layer can include, for example, polyethylene, polypropylene, polyethylene terephthalate, polyamide, polystyrene, cycloolefin copolymer, polyvinyl chloride, styrene butadiene, and mixtures thereof. In one preferred embodiment, the second layer material useful in the present invention can be polyethylene, polypropylene, and mixtures thereof. Some examples of commercially available materials useful in the second layer of the present invention include, for example, polyethylene (available from Berry Plastics) and biaxially oriented polypropylene (available from FILMTECH, INC.), and mixtures thereof. In another preferred embodiment, the second film layer, when different from the first layer, can be made of, for example, polyethylene having a density of 0.915 g / cc to 0.967 g / cc.

[0044] The thickness of the second layer used in the film of the present invention is, for example, 10 μm to 200 μm in one embodiment, 15 μm to 150 μm in another embodiment, and 20 μm to 125 μm in yet another embodiment.

[0045] In a general embodiment, one process for producing a multi-layer laminate product includes, for example: (I) applying an adhesive composition of the present invention to at least a portion of a surface of the first layer and / or the second layer; (II) contacting the first layer and the second layer such that an adhesive is disposed between the first layer and the second layer; (III) curing the adhesive to form a multi-layer laminate product including a first layer bonded to a second layer via the cured adhesive.

[0046] Although the laminate film structures of the present invention include films made from polymers bonded together using a barrier adhesive composition instead of a standard adhesive composition, the laminate film structures of the present invention still achieve similar or enhanced barrier properties. One of the advantageous properties exhibited by the laminate products made by the above-described processes of the present invention can include, for example, laminates having improved (i.e., reduced) oxygen transmission rates (OTR). In some embodiments, the laminate film structures can have a "barrier adhesive composition" (i.e., a reduced OTR) of "ccO2 / m 2 / day" and has an OTR of 750 cubic centimeters of oxygen per square meter per day or less, measured in accordance with ASTM method D3985.

[0047] Because laminate film structures can be designed with a variety of layer materials, number of layers, film thicknesses, and other properties, the OTR of a particular laminate structure will depend, for example, on the various properties of the first and second layers. By way of example, and not limitation thereby, the OTR of a laminate structure of the present invention is generally, in one embodiment, 15% lower than a laminate using a standard adhesive composition; in another embodiment, 25% lower than a laminate using a standard adhesive composition; and in yet another embodiment, 50% lower than a laminate using a standard adhesive composition. In yet another embodiment, the OTR of a laminate structure of the present invention is 10% to 90% lower than a laminate using a standard adhesive composition.

[0048] The laminate prepared as described above can be used in, for example, flexible packaging applications, and household and personal care applications.In one preferred embodiment, the laminate is used to make multi-layer laminate structure products or articles, such as packages, pouches, or containers for packaging food.In a preferred embodiment, the laminate is made from two layers of polymer film, with an adhesive layer disposed between the two film layers, which connects the two polymer films together.The process of making articles such as food packaging articles can be carried out by those skilled in the art of food packaging manufacturing.

[0049] As noted above, by using the barrier adhesive layer of the present invention in place of standard adhesives, there is a reduction in the permeability of oxygen through the laminate structure, and therefore articles made using such laminates will have the same advantageous gas barrier properties, such as improved (i.e., reduced) OTR exhibited by such laminates.

[0050] Furthermore, multi-layer laminates having an ABA structure can advantageously be simple and easily manufacturable structures and can be beneficially recyclable so that food packaging made from the laminates is environmentally friendly. The present specification includes the following aspects. Section 1: A polyurethane adhesive composition based on crystalline polycarbonate for producing adhesive laminate structures, comprising: (a) at least one isocyanate component; (b) at least one isocyanate-reactive component, (bi) at least one crystalline polycarbonate diol compound; (bii) at least one acrylic polymer compound, and (biii) at least one isocyanate-reactive component, including at least one solvent; and 1. An adhesive composition comprising: Section 2: Item 2. The adhesive composition according to item 1, wherein the weight ratio of component (a) to component (b) is 4:100 to 30:100. Section 3: Item 2. The adhesive composition according to item 1, wherein the at least one isocyanate component is selected from the group consisting of xylylene diisocyanate-based polyisocyanates, hexamethylene diisocyanate-based polyisocyanates, diphenylmethane diisocyanate-based polyisocyanates, toluene diisocyanate-based polyisocyanates, and mixtures thereof. Section 4: Item 2. The adhesive composition according to item 1, wherein the at least one crystalline polycarbonate diol compound has a structure of carbonate units and hydroxyl end groups and includes a compound that is solid over a temperature range of 10°C to 40°C. Section 5: Item 1, wherein the at least one crystalline polycarbonate diol compound comprises poly(hexanediol-carbonate), poly(butanediol-carbonate), and mixtures thereof. Item 6: Item 1, wherein the at least one acrylic polymer compound is selected from the group consisting of polylauryl acrylate, polybutyl acrylate, poly(2-ethylhexyl) acrylate, poly(ethyl acrylate-2-ethylhexyl acrylate), polylauryl methacrylate, acrylic copolymers made from two or more monomers (methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, styrene, vinyl acetate, and butadiene), and mixtures thereof. Section 7: Item 1. The adhesive composition according to item 1, wherein the at least one solvent is ethyl acetate, methyl ethyl ketone, or a mixture thereof. Section 8: Item 1, wherein the adhesive composition is used to form a laminate having an oxygen transmission rate (OTR) of less than 750 cubic centimeters per square meter per day. Section 9: 1. A process for producing a polyurethane adhesive composition based on crystalline polycarbonate for producing an adhesive laminate structure, comprising: (a) at least one isocyanate component; (b) at least one isocyanate-reactive component, (bi) at least one crystalline polycarbonate diol compound; (bii) at least one acrylic polymer compound, and (biii) mixing at least one isocyanate-reactive component with a blend of at least one solvent. Section 10: A multi-layer laminate product comprising: (A) at least a first layer; (B) at least a second layer; (C) at least one layer of the cured adhesive of paragraph 1 disposed between the first layer and the second layer, wherein the cured adhesive bonds the first layer to the second layer and provides a laminate having an oxygen transmission rate (OTR) of less than 750 cubic centimeters per square meter per day. Section 11: 1. A process for producing a multi-layer laminate product, comprising: (I) applying the adhesive according to item 1 to at least a portion of the surface of the first layer and / or the second layer; (II) contacting the first layer and the second layer such that the adhesive is disposed between the first layer and the second layer; (III) curing the adhesive to form a multi-layer laminate product comprising the first layer bonded to the second layer via the cured adhesive. Section 12: Item 11. A packaging container article comprising the laminate according to item 10. [Example]

[0051] The following examples are presented to further illustrate the invention, but should not be construed as limiting the scope of the claims. Unless otherwise indicated, all parts and percentages are by weight.

[0052] The various raw materials or compounding ingredients used in the inventive examples (Inv. Ex.) and comparative examples (Comp. Ex.) are described as follows: MOR-FREE™ C33 is an aliphatic isocyanate available from The Dow Chemical Company (Dow). ADCOTE™ 577 is an isocyanate-terminated compound available from Dow. ADCOTE™ 577B is a hydroxyl-terminated compound available from Dow. ETERNACOLL® UH-100 is a 1,6-hexanediol-based crystalline polycarbonate diol with a molecular weight (Mw) of 1,000 and a melting point of about 45° C., available from UBE Industries Company (UBE). ETERNACOLL® UH-200 is a 1,6-hexanediol-based crystalline polycarbonate diol with a Mw of 2,000 and a melting point of about 50° C., available from UBE. ETERNACOLL® PH-100 is an amorphous copolycarbonate diol with Mw of 1,000, in which 1,4-cyclohexanedimethanol and 1,6 hexanediol are applied as the copolycarbonate diol components, and is available from UBE. MODAFLOW® resin is an acrylic copolymer and is available from Allnex Inc. "BOPP" stands for biaxially oriented polypropylene. BOPP is a film having a thickness of 20 μm and is available from Filmtech Inc.

[0053] test 90°T peel test A 90° T peel test was performed on laminate samples consisting of two films, a primary film and a secondary film, adhesively bonded together. The laminate samples were cut into 15 mm wide strips, and each sample was pulled in a Thwing Albert™ QC-3A peel tester equipped with a 50 N loading cell. The laminate samples were pulled in the peel tester at a speed of 4 in / min (10 cm / min) on the 15 mm strips. The average force during the pull was recorded when the two films in the laminate separated (peeled). If one of the films stretched or broke, the maximum force or force at break was recorded. The final value for the laminate sample was the average of three separate sample strips tested. The failure mode (FM) or mode of failure (MOF) was recorded as follows: AS (Adhesive Split), indicating adhesive was found on both the primary and secondary films, or cohesive failure.

[0054] Oxygen Transmission Rate (OTR) Measurement The oxygen transmission rates (OTR) of the formed laminates were measured using a MOCON OXTRAN 2 / 21 under ASTM method D3985 ("Standard Test Method for Oxygen Gas Transmission Rate through Plastic Films and Sheets Using a Coulometric Sensor"). OTR data are reported in standard units of cc / m 2 The conditions used for the test to obtain the OTR measurements were 23°C and 85% relative humidity (RH).

[0055] Isocyanate Co-reactant General Procedure for Preparing Isocyanate Co-Reactants (CR) The coreactants (CR) listed in Table I are prepared using crystalline or amorphous polycarbonate diol compounds. The polycarbonate diol is first melted in an oven at 60°C, and then the melted crystalline or amorphous polycarbonate diol compound is mixed with ethyl acetate and an acrylic polymer at 60°C for 1 hour to form an isocyanate-reactive component composition.

[0056] [Table 1]

[0057] adhesive formulation General Procedure for Preparing Adhesive Formulations The adhesive formulations described in Table II are prepared by mixing the ingredients listed in Table V under the following conditions:

[0058] Suitable compounding ingredients, isocyanate-reactive components, and isocyanate components for preparing the adhesive formulations are listed in Table II. Using the adhesive of Inventive Example 1 as an example of preparing an adhesive formulation sample, approximately 2,541 g of the isocyanate component (Component B) and approximately 459 g of the isocyanate component (Component A) are charged to a plastic container. The materials are mixed for 30 minutes at room temperature (approximately 25° C.) using a mechanical mixer to obtain the compounded adhesive of Inventive Example 1.

[0059] Table II lists adhesive formulations of selected examples, all of which had the same amount of excess isocyanate.

[0060] [Table 2]

[0061] Coated laminate General Procedure for Preparing Coated Laminates A polyurethane adhesive is prepared as described above using the general procedure for preparing adhesive formulations. The adhesive is first coated onto a primary substrate via a gravure cylinder. The coated film is then passed through a three-zone oven. The coated film is then nipped to another substrate under a heated steel roll with a temperature of 90°C and a nip pressure set at 40 pounds per square inch (275.8 kPa). The laminated structure is passed through a final chill roll with a chill roll temperature of 17°C. The resulting laminate is then placed in a temperature-controlled chamber and cured at 23°C and 50% RH for 7 days.

[0062] Examples 4 to 6 Coated laminates were prepared using the polyurethane adhesive compositions of Inventive Examples 1-3 listed above in Table II and using the general procedure for preparing coated laminates described above. The resulting laminates of Inventive Examples 4-6 each had a coating weight of 3.5 g / m 2 The adhesive coating weight was 100g.

[0063] Comparative example C A coated laminate was prepared using the polyurethane adhesive composition of Comparative Example A set forth above in Table II and using the general procedure for preparing coated laminates described above. The resulting Comparative Example A laminate had a coating weight of 3.5 g / m 2 The adhesive coating weight was 100g.

[0064] Comparative example D The same general procedure for preparing the coated laminate as above was used in this Comparative Example B, except that a polyurethane adhesive containing approximately 55% by weight ADCOTE™ 577, 4.9% by weight ADCOTE™ 577B, and 40.1% by weight ethyl acetate was used. In this Comparative Example B, the laminate structure was passed through a final chill roll at a chill roll temperature of 17° C., after which the laminate was placed in a temperature controlled chamber and cured at 23° C. and 50% RH for 7 days. The laminate had a coating weight of 3.5 g / m 2 The adhesive coating weight was 100g.

[0065] Laminate / Adhesive Performance From the data set forth in Table III below, it can be seen that the laminates of Inventive Examples 4, 5, and 6, coated with the adhesive formulations of Inventive Examples 1, 2, and 3, respectively, containing crystalline polycarbonate, exhibited improved OTR barrier performance compared to Comparative Examples C and D, which were coated with adhesive formulations containing an amorphous polycarbonate backbone.

[0066] [Table 3]

Claims

1. A polyurethane adhesive composition based on crystalline polycarbonate for producing adhesive laminate structures, comprising: (a) at least one isocyanate component; (b) at least one isocyanate-reactive component, (bi) 15% to 45% by weight of at least one crystalline polycarbonate diol compound; (bii) 0.05% to 4% by weight of at least one acrylic polymer compound, and (biii) at least one isocyanate-reactive component, including at least one solvent; and Including, The polyurethane adhesive composition is used to form a laminate having an oxygen transmission rate (OTR) of less than 750 cubic centimeters per square meter per day.

2. 2. The adhesive composition of claim 1, wherein the weight ratio of component (a) to component (b) is from 4:100 to 30:

100.

3. 2. The adhesive composition of claim 1, wherein the at least one isocyanate component is selected from the group consisting of xylylene diisocyanate-based polyisocyanates, hexamethylene diisocyanate-based polyisocyanates, diphenylmethane diisocyanate-based polyisocyanates, toluene diisocyanate-based polyisocyanates, and mixtures thereof.

4. 2. The adhesive composition of claim 1, wherein the at least one crystalline polycarbonate diol compound comprises a compound having a structure of carbonate units and hydroxyl end groups, and being solid over a temperature range of 10°C to 40°C.

5. 10. The adhesive composition of claim 1, wherein the at least one crystalline polycarbonate diol compound comprises poly(hexanediol-carbonate), poly(butanediol-carbonate), and mixtures thereof.

6. 10. The adhesive composition of claim 1, wherein the at least one acrylic polymer compound comprises polylauryl acrylate, polybutyl acrylate, poly(2-ethylhexyl)acrylate, poly(ethyl acrylate-2-ethylhexyl acrylate), polylauryl methacrylate, acrylic copolymers made from two or more monomers including methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, styrene, vinyl acetate, butadiene, and mixtures thereof.

7. The adhesive composition of claim 1 , wherein the at least one solvent is ethyl acetate, methyl ethyl ketone, and mixtures thereof.

8. 1. A process for producing a polyurethane adhesive composition based on crystalline polycarbonate for producing an adhesive laminate structure, comprising: (a) at least one isocyanate component; (b) at least one isocyanate-reactive component, (bi) 15% to 45% by weight of at least one crystalline polycarbonate diol compound; (bii) 0.05% to 4% by weight of at least one acrylic polymer compound, and (biii) mixing at least one isocyanate-reactive component with a blend of at least one solvent; The process wherein the polyurethane adhesive composition is used to form a laminate having an oxygen transmission rate (OTR) of less than 750 cubic centimeters per square meter per day.

9. A multi-layer laminate product comprising: (A) at least a first layer; (B) at least a second layer; (C) at least one layer of the cured adhesive of claim 1 disposed between the first layer and the second layer, wherein the cured adhesive bonds the first layer to the second layer to provide a laminate having an oxygen transmission rate (OTR) of less than 750 cubic centimeters per square meter per day.

10. 1. A process for producing a multi-layer laminate product, comprising: (I) applying the adhesive of claim 1 to at least a portion of the surface of the first layer and / or the second layer; (II) contacting the first layer and the second layer such that the adhesive is disposed between the first layer and the second layer; (III) curing the adhesive to form a multi-layer laminate product comprising the first layer bonded to the second layer via the cured adhesive.

11. A packaging container item comprising the laminate described in claim 9.

Images