Polyurethane adhesive composition for film lamination

Abstract

The present invention relates to a polyurethane adhesive composition for film lamination, in particular in flexible food packaging, and further to a method for producing a laminate using said polyurethane adhesive composition, and to a laminate obtained by said method.

Description

[Technical Field]

[0001] The present invention relates to a polyurethane adhesive composition for film lamination, particularly in flexible food packaging. The present invention also relates to a method for producing a laminate using the polyurethane adhesive composition, and to a laminate obtained by the method. [Background technology]

[0002] Product packaging is evolving from sealed metal cans and glass bottles to sealed flexible packaging, such as pouches. As an example, animal and human food is now sold in both traditional metal cans and flexible pouches. Flexible packaging can easily change shape when filled with food or other products and then closed or sealed. Flexible packaging is typically prepared from two layers of flexible packaging material, which are overlapped and sealed around most of the perimeter to form a cavity. Typically, the two layers of flexible packaging material are heat-sealed by applying heat and pressure to fuse the layers together around the thin portion of the package perimeter. The food or other product is placed into the cavity through an opening, and the opening is closed by heat-sealing the layers together. The sealed package and the enclosed product can be heated for storage purposes. In demanding applications, the sealed package and the enclosed product can be sterilized at temperatures up to 135°C.

[0003] Flexible packaging materials are prepared by laminating two or more layers of film. Each film is selected for specific properties. For example, a flexible packaging material may be a three-layer laminate. The inner layer contacts the packaged product. Polypropylene has desirable product contact properties as well as heat sealability and can be used as the inner layer. The middle layer provides a barrier against moisture, oxygen, and / or light. Metal films or foils have desirable barrier properties, and metal films such as aluminum foil can be used as the middle layer. The outer layer protects the package and also provides a surface for printing information such as contents, packaging date, and warnings. Polyester film is tough and can accept printing inks and can be used as the outer layer. Flexible packaging materials can range in thickness from about 1 μm to about 75 μm.

[0004] Each layer of flexible packaging material is bonded to the adjacent layer by an adhesive. The adhesive can be applied from a solution in a suitable solvent using a gravure press or smooth roll coating cylinder, or it can be applied solvent-free using specialized coating machines to the layer, which is then laminated to another layer. The laminated packaging material is dried, if necessary, and collected into a roll. The roll may be stored for a period of time, depending on the application, to allow the adhesive to cure before use.

[0005] While many types of adhesives are possible, polyurethane-based adhesives are preferred for use in flexible packaging materials due to their many desirable properties, including good adhesion to the materials in each layer, high bond strength, resistance to heat such as heat sealing or retorting, and resistance to chemically aggressive products. Typically, an isocyanate-containing polyurethane prepolymer obtained by reacting an excess of diisocyanate with a polyether and / or polyester containing two or more active hydrogen groups per molecule is used in combination with a second component. The second component is usually a polyether polyol and / or polyester polyol. The two components are combined in a predetermined ratio just before use and applied to one surface of a film, which is then laminated to another substrate.

[0006] One concern that has been raised regarding flexible packaging materials manufactured for use as food packaging is government regulations, which require that food packaging be safe when in contact with food. In accordance with the 11th Amendment to the EU Plastics Regulation (EU 10 / 2011), 3-glycidyloxypropyltrimethoxysilane (GLYMO), commonly used as an adhesion promoter in current adhesive products for bonding flexible packaging materials, has been evaluated as potentially genotoxic. To ensure safe use in food applications, a limit of 0.15 μg / kg has been established. This substance is expressly permitted for use; however, this means that packaging manufacturers must ensure that its concentration, as well as the concentrations of its derivatives, under conditions of use are below specific migration limits. Summary of the Invention [Problem to be solved by the invention]

[0007] However, polyurethane adhesives for demanding applications must withstand high thermal and chemical requirements without compromising adhesive strength and ease of application. Therefore, it would be desirable to provide a polyurethane adhesive composition that does not contain GLYMO or other epoxidized silanes, particularly for bonding flexible films for packaging in high-temperature food contact and medical retort applications. [Means for solving the problem]

[0008] A first object of the present invention is to provide a polyurethane adhesive composition comprising: a polyol component including at least one polyester polyol which is a reaction product of at least one alicyclic polyol, at least one heterocyclic polyol, at least one linear or branched aliphatic polyol, and at least one polyfunctional carboxylic acid; and an isocyanate component including a combination of at least one aliphatic or alicyclic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups, and / or a reaction product of at least one aliphatic or alicyclic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups, a cured adhesive thereof, and a method for producing the same.

[0009] Another object of the present invention is to provide a flexible packaging laminate that includes the cured adhesive and a method for making the same. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention is described in more detail in the following paragraphs. Each aspect described in this manner may be combined with any other aspect or aspects, unless expressly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0011] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs. As a further guide, term definitions are included to better understand the teachings of the present invention.

[0012] As used herein, the singular forms "a," "an," and "the" include both the singular and plural referents unless the context clearly dictates otherwise.

[0013] As used herein, the terms "comprising," "comprises," and "comprised of" are synonymous with "including," "includes," or "containing," and are inclusive or open-ended and do not exclude additional, unrecited components, elements, or method steps.

[0014] The recitation of numerical endpoints includes all values ​​and fractions subsumed within the respective ranges as well as the recited endpoints.

[0015] All references cited herein are incorporated by reference in their entirety.

[0016] When referring to the molecular weight of a polymer herein, unless otherwise specified, the reference refers to the number average molecular weight M n The number average molecular weight M of a polymer n can be determined, for example, by gel permeation chromatography (GPC) according to DIN 55674 using THF as eluent. Unless otherwise stated, all molecular weights given are determined by GPC calibrated with polystyrene standards. The average molecular weight M w is M n The solubility can be determined by GPC as described for

[0017] The disclosed polyurethane adhesive composition comprises or consists of a polyol component including at least one polyester polyol, which is the reaction product of at least one cycloaliphatic polyol, at least one heterocyclic polyol, at least one linear or branched aliphatic polyol, and at least one polyfunctional carboxylic acid; and an isocyanate component including a combination of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups, and / or a reaction product of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups. The adhesive composition is essentially free, and preferably free, of alkoxysilanes having epoxide groups, such as GLYMO.

[0018] <Polyol component> The polyol component in the polyurethane adhesive composition according to the present invention comprises a polyester polyol obtained from a reaction mixture comprising at least one alicyclic polyol, at least one heterocyclic polyol, at least one linear or branched aliphatic polyol, and at least one multifunctional carboxylic acid.

[0019] Generally, the molecular weight of the polyester polyol used in the adhesive composition is not particularly limited as long as it does not adversely affect the properties of the adhesive composition and the cured adhesive. Preferably, the polyester polyol has a molecular weight M of 200 to 20,000 g / mol, particularly 1,000 to 10,000 g / mol. n It has.

[0020] In the present invention, the polyester polyol may preferably have an acid value of 0.1 to 2 mg KOH / g. When the acid value of the polyester polyol is within the above range, the adhesive composition for food packaging films of the present invention has a viscosity more suitable for application and excellent adhesion to the film. The "acid value" of the polyester polyol according to the present invention is expressed as the number of milligrams of potassium hydroxide required to neutralize the acid, assuming that all acid groups contained in 1 g of resin are free acids. Therefore, even if acid groups exist as bases in an actual system, they are assumed to be free acids. The "acid value" according to the present invention is determined by dissolving the polyester polyol in a solvent, adding phenolphthalein as an indicator, and titrating with a 0.1 mol / l potassium hydroxide-ethanol solution according to DIN 53240.

[0021] In the present invention, the polyester polyol may have a hydroxyl value of 5 to 350 mgKOH / g. When the hydroxyl value of the polyester polyol is within the above range, the adhesive composition for food packaging films of the present invention has a viscosity more suitable for application and exhibits superior adhesion to the film. In this specification, the term "hydroxyl value" refers to the number of milligrams of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when 1 g of resin is acetylated.

[0022] The "hydroxyl number" according to the present invention is determined in accordance with DIN 51558 by adding an acetylating agent to a polyester polyol, heating it in a glycerin solution, cooling it, and then adding phenolphthalein as an indicator and titrating it with a potassium hydroxide-ethanol solution.

[0023] In the present invention, the polyester polyol may have a glass transition temperature of -20°C to 100°C. The glass transition temperature of the polyester polyol is measured using a differential scanning calorimeter. A DSC curve of an appropriate amount of sample was measured at a heating rate of 10°C / min, and the temperature at the inflection point of the obtained DSC curve was regarded as the glass transition temperature.

[0024] In the present invention, the polyester polyol is liquid at room temperature, which can provide further ease of processing when formulating the adhesive composition.

[0025] The cycloaliphatic polyol may have one, two or more rings and two or more hydroxyl groups. Preferably, the cycloaliphatic polyol is selected from 1,4-cyclohexanedimethanol, cyclobutanediol, cyclopentanediol, 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, cyclohexanedimethanol, tricyclo[5.2.1.0.2.6]decanedimethanol, bicyclo[4.3.0]nonanediol, dicyclohexanediol, tricyclo[5.3.1.1]dodecanediol, bicyclo[4.3.0]nonanedimethanol, tricyclo[5.3.1.1]dodecanediethanol, spiro[3.4]octanediol, butylcyclohexanediol, 1,1'-bicyclohexylidenediol, cyclohexanetriol, hydrogenated bisphenol A, 1,3-adamantanediol, and mixtures thereof. More preferably, the cycloaliphatic polyol is selected from 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, and mixtures thereof. In particular, the cycloaliphatic polyol is 1,4-cyclohexanedimethanol (CHDM).

[0026] The alicyclic polyol is present in the polyester polyol reaction mixture in an amount of 1 to 25 wt. %, preferably 2 to 20 wt. %, based on the weight of the reaction mixture. Less than this amount may result in poor adhesive performance. More than this amount may result in the resulting polyester polyol remaining solid at reaction temperatures and not being capable of further processing.

[0027] The heterocyclic polyol may have one, two or more rings, preferably two or more rings and two or more hydroxyl groups, and may be selected from 1,4:3,6-dianhydrohexitol (such as isosorbide, isomannide, or isoidide), spiroglycol, 2,4:3,5-di-O-methylenemannitol, and 2,3:4,5-di-O-methylene lactose, preferably isosorbide, spiroglycol, 2,4:3,5-di-O-methylenemannitol, and 2,3:4,5-di-O-methylene lactose, as shown below, in particular isosorbide. [ka]

[0028] The heterocyclic polyol is present in the polyester polyol reaction mixture in an amount of from 1 to 40 weight percent, preferably from 1.5 to 30 weight percent, based on the weight of the reaction mixture.

[0029] There are no limitations on the linear or branched aliphatic polyol, as long as it does not adversely affect the properties of the polyester polyol. The linear or branched aliphatic polyol may have a low molecular weight and two or more hydroxyl groups. Examples of linear or branched aliphatic polyols include ethylene glycol, propylene glycol (such as 1,2-propylene glycol and 1,3-propylene glycol), glycerol, pentaerythritol, trimethylolpropane, 1,4,6-octanetriol, butanediol, pentanediol, hexanediol, dodecanediol, octanediol, chloropentanediol, glycerol monoallyl ether, glycerol monoethyl ether, diethylene glycol, 2-ethylhexanediol-1,4,1,2,6-hexanetriol, 1,3,5-hexanetriol, and 1,3-bis-(2-hydroxyethoxy)propane. In one embodiment, neopentyl glycol and hexanediol are not used in the adhesive composition due to potential migration concerns, while in another embodiment, it is more preferred to use linear or branched aliphatic polyols such as diethylene glycol and / or propylene glycol.

[0030] The linear or branched aliphatic polyol is present in the polyester polyol reaction mixture in an amount of from 1 to 40% by weight, preferably from 2 to 25% by weight, based on the weight of the reaction mixture.

[0031] Polyester polyols can be prepared by polycondensing the above-mentioned polyols with a substoichiometric amount of a polyfunctional carboxylic acid to form the polyester polyol, according to methods known in the art. Preferably, the polyfunctional carboxylic acid has 2 to 14 carbon atoms, such as a dicarboxylic acid and / or tricarboxylic acid, or a reactive derivative thereof. Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid, 3,7-dimethyldecanedioic acid, phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, trimesic acid, and cyclohexanedicarboxylic acid. These dicarboxylic acids can be used alone or in combination. Examples of carboxylic acid anhydrides include acetic anhydride, propionic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, and trimellitic anhydride. These dicarboxylic acid anhydrides may be used alone or in combination. In one embodiment, the polyfunctional carboxylic acid is selected from adipic acid, azelaic acid, terephthalic acid, isophthalic acid, and mixtures thereof.

[0032] The polyfunctional carboxylic acid is present in the polyester polyol reaction mixture in an amount of 30 to 70 weight percent, preferably 35 to 60 weight percent, based on the weight of the reaction mixture.

[0033] The reaction mixture may optionally contain at least one catalyst to promote the reaction of the polyol with the polyfunctional carboxylic acid.

[0034] The polycondensation of the polyol and the polyfunctional carboxylic acid may be carried out in the presence of a catalyst.

[0035] Suitable catalysts include, for example, those of general formula I: [ka] [In the formula, M is a metal selected from the group consisting of aluminum, titanium, magnesium, or zirconium, and R 1 represent the same or different linear or branched hydrocarbon groups containing 1 to 8 carbon atoms, and x has a value of 2, 3 or 4. The catalysts are compounds corresponding to the following: Suitable catalysts are, for example, aluminum alkoxides, titanium alkoxides, magnesium alkoxides, and zirconium alkoxides. Particularly suitable catalysts are, for example, aluminum trimethoxide, aluminum triethoxide, aluminum triisopropoxide, aluminum trisec-butoxide, aluminum tritrate-butoxide, titanium(IV) methoxide, titanium(IV) ethoxide, titanium(IV) isopropoxide, titanium(IV) butoxide, titanium(IV) 2-ethylhexoxide, zirconium(IV) ethoxide, zirconium(IV) propoxide, zirconium(IV) butoxide, zirconium(IV) isopropoxide, zirconium(IV) tert-butoxide, magnesium methoxide, magnesium ethoxide, magnesium butoxide, magnesium propoxide, or magnesium phenoxide.

[0036] Other suitable catalysts for the process according to the invention are tin compounds, more particularly organotin carboxylates such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin bis-(2-ethylhexanoate) or other organotin compounds such as dibutyltin oxide, dibutyltin dimethoxide, dibutyltin dibromide, dibutyltin dichloride, di-tert-butyltin dichloride, dimethyltin dibromide, dimethyltin dichloride, diphenyltin dichloride, or tin octoate. Among the catalysts mentioned, dibutyltin dilaurate, dibutyltin oxide, and dibutyltin diacetate are preferred.

[0037] Other suitable catalysts are compounds containing at least one metal selected from the group consisting of antimony, iron, cobalt, nickel, copper, chromium, manganese, molybdenum, tungsten, and lead. Oxides, halides, carboxylates, phosphates, or organometallic compounds of the listed metals are particularly suitable. Examples of particularly suitable catalysts include iron acetate, iron benzoate, iron naphthenate; iron acetylacetonate, manganese acetate, manganese naphthenate, and manganese acetylacetonate.

[0038] The catalyst is present in the polyester polyol reaction mixture in an amount of 0 to 0.1 weight percent, preferably 0.0001 to 0.05 weight percent, based on the weight of the reaction mixture.

[0039] The preparation of polyester polyols according to the present invention is well known to those skilled in the art. A typical preparation method includes the steps of: (1) providing at least one alicyclic polyol, at least one heterocyclic polyol, at least one linear or branched aliphatic polyol, and at least one polyfunctional carboxylic acid to form a mixture; (2) gradually heating the mixture to 200-220°C and maintaining it under a nitrogen stream for 20-40 hours; (3) gradually reducing the pressure to 10-300 mbar to complete the reaction; and (4) cooling the reaction mixture when the acid value of the reaction mixture is 2 or less to obtain a polyester polyol, wherein at least one catalyst is optionally added to the mixture of steps (1) and / or (2).

[0040] In addition to polyester polyols, polyacetal and polyether polyols may be used in the polyol component. Polyacetal refers to compounds obtained by reacting glycols with aldehydes, such as diethylene glycol, hexanediol, or a mixture thereof, condensed with formaldehyde. The polyacetal that can be used in the context of the present disclosure may also be obtained by polymerization of cyclic acetals.

[0041] The polyether polyol is preferably a polyether diol containing primary hydroxyl groups or a mixture of primary and secondary hydroxyl groups. Examples of suitable polyether polyols are polyoxyalkylene polyols, such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polybutylene glycol. Homopolymers or copolymers of the listed polyoxyalkylene polyols, as well as mixtures thereof, are also suitable for the purposes of the present invention. Particularly suitable copolymers are those containing an adduct of a compound selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, propylene glycol, triethylene glycol, 2-ethylhexanediol-1,3-glycerin, trimethylolpropane, trimethylolethane, tris(hydroxyphenyl)propane, triethanolamine, and triisopropylamine with at least one compound selected from the group consisting of ethylene oxide, propylene oxide, and butylene oxide.

[0042] Further suitable polyols that may be used in the polyol component include polycarbonates, which can be obtained, for example, by reacting a diol, such as propylene glycol, butane-1,4-diol, or hexane-1,6-diol, diethylene glycol, triethylene glycol, or tetraethylene glycol, or a mixture of two or more thereof, with a diaryl carbonate, such as diphenyl carbonate, or phosgene.

[0043] Similarly, polyacrylates containing hydroxyl groups are suitable for use in the polyol component. These polyacrylates can be obtained, for example, by polymerizing ethylenically unsaturated monomers containing OH groups. Such monomers can be obtained, for example, by esterifying ethylenically unsaturated carboxylic acids with difunctional alcohols, with the alcohol generally being present in a slight excess. Examples of ethylenically unsaturated carboxylic acids suitable for this purpose are acrylic acid, methacrylic acid, crotonic acid, or maleic acid. Corresponding esters containing OH groups include, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, or 3-hydroxypropyl methacrylate, or a mixture of two or more thereof.

[0044] In one preferred embodiment, the reaction mixture from which the polyester polyols according to the invention are obtained comprises, based on the total weight of the reaction mixture, one of the following: i) 30 to 70% by weight, preferably 35 to 60% by weight, of at least one polyfunctional carboxylic acid; ii) 1 to 40% by weight, preferably 1.5 to 30% by weight, of at least one heterocyclic polyol; iii) 1 to 25 wt. %, preferably 2 to 20 wt. %, of at least one cycloaliphatic polyol; iv) 1 to 40% by weight, preferably 2 to 25% by weight, of at least one linear or branched aliphatic polyol; and v) 0 to 0.1% by weight, preferably 0.0001 to 0.05% by weight, of at least one catalyst.

[0045] <Isocyanate component> To extend the chain length of the polyol, an isocyanate component is reacted with the polyol component to obtain a prepolymer or polyurethane adhesive. According to the present invention, the isocyanate component comprises or consists of a combination of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups, and / or a reaction product of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups. In one embodiment, the isocyanate component comprises or consists of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups. In another embodiment, the isocyanate component comprises or consists of a reaction product of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups.

[0046] The reaction product of at least one aliphatic or alicyclic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound that does not have an epoxide group is known in the art, and can be the reaction product of at least one aliphatic or alicyclic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound that does not have an epoxide group.Such an alkoxysilane-functionalized isocyanate compound can be prepared, for example, according to EP 0158893 A1, by reacting at least one hydrolyzable alkoxysilane compound that does not have an epoxide group with an excess of an aliphatic or alicyclic isocyanate-functionalized compound.

[0047] The aliphatic or cycloaliphatic isocyanate-functionalized compound may be any of aliphatic isocyanate and cycloaliphatic isocyanate monomers and / or oligomers such as dimers, trimers, etc., as long as the desired adhesive of the present invention can be obtained. Considering that the adhesive is used for food packaging applications, it is preferable to contain aliphatic isocyanate or cycloaliphatic isocyanate monomers or oligomers.

[0048] As used herein, "aliphatic isocyanate" refers to a monomer or oligomer having a linear hydrocarbon chain to which an isocyanate group is directly bonded and having no cyclic hydrocarbon chain. An "aliphatic isocyanate" may have an aromatic ring, but the isocyanate group is not directly bonded to the aromatic ring. Furthermore, as used herein, a cyclic hydrocarbon chain does not include an aromatic ring.

[0049] "Alicyclic isocyanate" means a monomer or oligomer having a cyclic hydrocarbon chain, which may have an open-chain hydrocarbon chain. The isocyanate group may be directly bonded to the cyclic hydrocarbon chain, or to any open-chain hydrocarbon chain that may be present. The "alicyclic isocyanate" may have an aromatic ring, but the isocyanate group is not directly bonded to the aromatic ring.

[0050] For example, 4,4'-diphenylmethane diisocyanate corresponds to an aromatic isocyanate because the isocyanate group is directly bonded to the aromatic ring. On the other hand, for example, xylylene diisocyanate has an aromatic ring, but the isocyanate group is not directly bonded to the aromatic ring but is bonded to a methylene group, so it corresponds to an aliphatic isocyanate. The aromatic ring may have a ring-fused structure in which two or more benzene rings are fused.

[0051] Examples of aliphatic isocyanates include 1,2-ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 2,2,4(2,4,4)-trimethyl-1,6-hexamethylene diisocyanate (TMDI), 1,9-diisocyanato-5-methylnonane, 1,8-diisocyanato-2,4-dimethyloctane, 1,12-dodecane diisocyanate, ω,ω'-diisocyanatodipropyl ether, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 1,4-di ...4-diisocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 1,4-diisocyanatomethyl-3, Examples of diisocyanatoisocyanates include methyl-2,3,5,6-tetramethylcyclohexane, 2-methyl-1,5-diisocyanatopentane (MPDI), 2-ethyl-1,4-diisocyanatobutane, 1,10-diisocyanatodecane, 1,5-diisocyanatohexane, 1,3-diisocyanatomethylcyclohexane, 1,4-diisocyanatomethylcyclohexane, xylyl diisocyanate (XDI), tetramethylxylyl diisocyanate (TMXDI), methyl 2,6-diisocyanatohexanoate (lysine diisocyanate), and dimers or trimers thereof, such as IPDI trimer and HDI trimer.

[0052] Examples of alicyclic isocyanates include 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane (isophorone diisocyanate), 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated xylylene diisocyanate), bis(4-isocyanatocyclohexyl)methane (hydrogenated diphenylmethane diisocyanate), 1,4-diisocyanatocyclohexane, and oligomers thereof.

[0053] The aliphatic or alicyclic isocyanate-functionalized compound is preferably a compound having three or more isocyanate groups. Such isocyanate-functionalized compounds are preferably adducts of various polyisocyanates with polyols such as 2-methylpentane-2,4-diol and trimethylolpropane, adducts of diisocyanates such as HDI, XDI, and IPDI with trimethylolpropane, and trimers having an isocyanurate ring. Polyisocyanate-modified products may include carbodiimide groups, uretdione groups, uretonimine groups, biuret groups reacted with water, isocyanurate groups, or modified products having two or more of these groups.

[0054] In one preferred embodiment, the aliphatic or cycloaliphatic isocyanate-functionalized compound is selected from IPDI, HDI, XDI, adducts thereof, oligomers thereof, and mixtures of the foregoing.

[0055] The hydrolyzable silane compound without epoxide group may have at least one functional group reactive with isocyanate group, which is known to those skilled in the art.The functional group reactive with isocyanate group is particularly OH group, thiol group, carboxyl group, primary and secondary amino group, and mixtures thereof, preferably carboxyl group, primary and secondary amino group, and mixtures thereof, more preferably primary and secondary amino group.

[0056] Examples of such hydrolyzable silane compounds containing at least one primary and / or secondary amino group are 3-aminopropyltrimethoxysilane (APS), 3-aminopropyltriethoxysilane, 3-aminopropyltriisopropoxysilane, 2-aminoethyltrimethoxysilane, 2-aminoethyltriethoxysilane, 2-aminoethyltriisopropoxysilane, aminomethyltrimethoxysilane, aminomethyltriethoxysilane, aminomethyltriisopropoxysilane, 3-(2-aminoethyl)aminopropyltrieth ... Trimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltriisopropoxysilane, 2-(2-aminoethyl)aminoethyltrimethoxysilane, 2-(2-aminoethyl)aminoethyltriethoxysilane, 2-(2-aminoethyl)aminoethyltriisopropoxysilane, 3-(3-aminopropyl)aminopropyltrimethoxysilane, 3-(3-aminopropyl)aminopropyltriethoxysilane, 3-(3-aminopropyl)aminopropyltriiso Propoxysilane, diethylenetriaminopropyltrimethoxysilane, diethylenetriaminopropyltriethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, N-(n-butyl)-3-aminopropyltriethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyltrimethoxysilane, N-ethyl-γ-aminoisobutyltrimethoxysilane, N-ethyl-γ-aminoisobutyltriethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltriethoxysilane aminopropyltrimethoxysilane hydrochloride, N-phenyl-γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, N-methyl[3-(trimethoxysilyl)propyl]carbamate, and / or N-trimethoxysilylmethyl-O-methylcarbamate, and also bis[γ-(triethoxysilyl)propyl]amine, and bis[γ-(trimethoxysilyl)propyl]amine.

[0057] Examples of hydrolyzable silane compounds containing at least one thiol group are 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltriisopropoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane and / or 2-mercaptoethyltriisopropoxysilane.

[0058] In one preferred embodiment, bis[γ-(triethoxysilyl)propyl]amine and bis[γ-(trimethoxysilyl)propyl]amine are particularly preferred as the hydrolyzable silane compound.

[0059] The isocyanate component typically has an NCO content (determined in accordance with Spielberger, DIN EN ISO 11909:2007-05) of 10 to 25% by weight, preferably 15 to 20% by weight, and an average NCO functionality of 1 to 3.

[0060] When present, the reaction product of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound without an epoxide group is present in the isocyanate component in an amount of 1 to 40 wt %, preferably 5 to 20 wt %, based on the weight of the isocyanate component.

[0061] When present, the aliphatic or cycloaliphatic isocyanate-functionalized compound used as the sole component is present in the isocyanate component in an amount of 1 to 50 weight percent, preferably 10 to 40 weight percent, based on the weight of the isocyanate component.

[0062] When present, the hydrolyzable alkoxysilane compound having no epoxide groups is present in the isocyanate component in an amount of 1 to 10% by weight, preferably 2 to 8% by weight, based on the weight of the isocyanate component.

[0063] According to the present invention, the weight ratio of the polyol component to the isocyanate component is 15:1 to 1:5, preferably 12:1 to 1:3, and more preferably 10:1 to 2:1.

[0064] Surprisingly, the inventors have found that even without the use of GLYMO as an adhesion promoter, the adhesive composition maintains an excellent portfolio of properties such as viscosity, initial bond strength, aged bond strength, sterilization bond strength, and solvent resistance.

[0065] Another aspect of the present invention is directed to a two- or multi-component adhesive system, preferably a two-component system, comprising the adhesive composition according to the present invention. Such two- or multi-component adhesive systems may contain at least one solvent, as described above, or may be solvent-free. The polyol and isocyanate components are stored separately in different parts and mixed in a predetermined ratio immediately before use. Crosslinking of the adhesive system is based on the reaction of reactive isocyanate groups in the isocyanate component with OH groups in the polyol component. Another crosslinking method involves the reaction of NCO groups with moisture from the applied adhesive composition, the substrate, or the surrounding environment, resulting in the formation of urea groups. These crosslinking reactions are known and may occur simultaneously.

[0066] Yet another aspect of the present invention is directed to one-, two-, or multi-component adhesive systems containing a prepolymer that is a reaction product of an adhesive composition according to the present invention. These adhesive systems cure by reaction of the NCO groups with moisture from the applied adhesive composition, the substrate, or the surrounding environment. Such adhesive systems may contain at least one solvent, as described above, or may be solvent-free. Such adhesive systems may be reactive hot-melt adhesive systems. In one embodiment, the adhesive system is a one-component reactive hot-melt adhesive system containing a prepolymer. In another embodiment, the adhesive system is a two-component adhesive system containing a prepolymer as the isocyanate component and at least one polyol as the polyol component. There is no limitation on the polyol reacted with the prepolymer. Examples include those described above for producing polyester polyols or other polyols used in the polyol component of adhesive compositions.

[0067] The corresponding prepolymers usually have an NCO content (determined according to Spielberger, DIN EN ISO 11909:2007-05) of 10 to 25% by weight, preferably 15 to 20% by weight, and have an average NCO functionality of 1 to 3.

[0068] The molecular weight (Mn) of the prepolymer is in the range of 300 to 20,000 g / mol, preferably less than 12,000, in particular less than 8,000 g / mol.

[0069] The adhesive composition or adhesive system according to the present invention may further comprise additives. These additives may be used to affect the properties of the composition, such as mechanical properties and thermal conductivity. Preferably, the one or more additives are selected from the group consisting of fillers, pigments, rheology modifiers, driers, flame retardants, curing agents, surfactants, and defoamers. The additives may be included in the polyol component and / or the isocyanate component and / or the adhesive system, as long as they are inert to the other components.

[0070] A catalyst can be used in conjunction with the aliphatic or cycloaliphatic isocyanate-functionalized compound or prepolymer. The catalyst promotes the crosslinking reaction between the hydroxyl groups and the isocyanate groups of the aliphatic or cycloaliphatic isocyanate-functionalized compound or prepolymer. Examples of catalysts include tertiary amine compounds and organometallic compounds.

[0071] Examples of tertiary amine compounds include triethylamine, triethylenediamine, N,N-dimethylbenzylamine, N-methylmorpholine, diazabicycloundecene (also known as DBU), and the like.

[0072] Examples of organometallic compounds include tin compounds and non-tin compounds.

[0073] Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (also known as DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

[0074] Examples of non-tin compounds include titanium compounds such as dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride, lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate, iron compounds such as iron ethylhexanoate and iron 2,4-pentadionate, cobalt compounds such as cobalt benzoate and cobalt 2-ethylhexanoate, zinc compounds such as zinc naphthenate and zinc 2-ethylhexanoate, and zirconium naphthenate. Among these, diazabicycloundecene (also known as DBU), dibutyltin dilaurate (also known as DBTDL), and zinc 2-ethylhexanoate are preferred from the standpoints of reactivity and hygiene.

[0075] The catalysts may be used alone or in combination of two or more.

[0076] The adhesive composition or adhesive system according to the invention may contain or be solvent-free. If present, examples of organic solvents include heterocyclic, aliphatic, or aromatic hydrocarbons, such as toluene, isophorone, or xylene; monohydric or polyhydric alcohols, such as ethylhexanol, butoxypropanol, isopropanol, butyl diglycol, methanol, ethanol, propanol, and butanol; ethers, such as diethylene glycol dimethyl ether and dipropylene glycol methyl ether, ethyl glycol, and butyl glycol; esters, such as ethyl acetate, butyl acetate, pentyl acetate, or ethyl ethoxypropionate; ketones, such as cyclohexanone, methyl ethyl ketone (MEK), methyl amyl ketone, methyl isobutyl ketone (MIBK), and acetone; and amides, such as N-methylpyrrolidone, N-ethylpyrrolidone, and dimethylformamide.

[0077] The adhesive composition or adhesive system for food packaging films of the present invention can be produced by mixing the components / parts and optional additives. The mixing method is not particularly limited as long as the desired adhesive for food packaging films of the present invention is obtained. The mixing order of the components / parts is also not particularly limited. The adhesive composition for food packaging films of the present invention can be produced without requiring a special mixing method or mixing order. Therefore, the resulting adhesive for food packaging films has excellent both adhesive strength and resistance to contents.

[0078] In a preferred embodiment, the cured adhesive has an adhesive strength according to DIN 53357 of at least 3 N / 15 mm, preferably at least 4 N / 15 mm, after storage for 7 days.

[0079] In another preferred embodiment, the cured adhesive has an adhesive strength according to DIN 53357 of 5 N / 15 mm or more, preferably 6 N / 15 mm or more, after being stored at 40°C for 7 days and sterilized at 131°C for 30 minutes.

[0080] In yet another preferred embodiment, the cured adhesive has an adhesive strength according to DIN 53357 of at least 4 N / 15 mm, preferably at least 5 N / 15 mm, after being stored at 40°C for 7 days and sterilized with oleic acid at 131°C for 30 minutes.

[0081] In another aspect, the present invention is directed to a flexible packaging material comprising: a first layer comprising a first polyolefin or a first polyester; a second layer comprising a second polyolefin, which may be the same as or different from the first polyolefin, a second polyester, which may be the same as or different from the first polyester, or a metal foil; and a cured adhesive of the present invention adhering the first and second layers together.

[0082] In yet another aspect, the present invention is directed to a method for making a flexible film laminate, comprising combining the components of a polyurethane adhesive system according to the present invention in predetermined weight ratios to form an adhesive mixture; disposing the adhesive mixture on at least a portion of one surface of a first flexible film; bonding the first flexible film and a second flexible film, wherein the adhesive mixture is interposed between the first flexible film and the second flexible film; and curing the adhesive mixture.

[0083] Films coated and bonded together using the adhesive composition / system may comprise any material known in the art to be suitable for use in flexible packaging, including both polymeric and metallic materials, as well as paper (including treated or coated paper). Thermoplastics are particularly preferred for use as at least one layer. The materials selected for the individual layers of the laminate are chosen to achieve a particular combination of desired properties, such as mechanical strength, tear resistance, elongation, puncture resistance, flexibility / rigidity, gas and water vapor permeability, oil and grease permeability, heat sealability, optical properties (transparent, translucent, opaque, etc.), formability, merchantability, and relative cost. Individual layers may be pure polymers or blends of different polymers. Polymer layers are often formulated with colorants, anti-slip, anti-block, and anti-static processing aids, plasticizers, lubricants, fillers, stabilizers, etc. to enhance the properties of the particular layer.

[0084] Particularly preferred polymers for use include, but are not limited to, polyethylene [including low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HPDE), high molecular weight high density polyethylene (HMW-HDPE), linear low density polyethylene (LLDPE), linear medium density polyethylene (LMPE)], polypropylene (PP), oriented polypropylene, polyesters such as poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT), ethylene vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EBA), and the like. Examples include ethylene-methyl copolymer (EMA), ethylene-methacrylate (ionomer), hydrolyzed ethylene-vinyl acetate copolymer (EVOH), polyamide (nylon), polyvinyl chloride (PVC), poly(vinylidene chloride) copolymer (PVDC), polybutylene, ethylene-propylene copolymer, polycarbonate (PC), polystyrene (PS), styrene copolymer, high impact polystyrene (HIPS), acrylonitrile-butadiene-styrene polymer (ABS), acrylonitrile copolymer (AN), polyamide (nylon), polylactic acid (PLA), and regenerated cellulose film (cellophane).

[0085] If desired, the polymer surface may be treated or coated. For example, a polymer film may be metallized by depositing a thin metal vapor, such as aluminum, onto the surface of the film. Metallization may enhance the barrier properties of the finished laminate. The polymer film surface may also be coated with an anti-fog agent or the like, or pre-treated with electrical or corona discharge, or ozone or other chemicals, to enhance adhesion receptivity. SiO x or AlO x A coating of an inorganic oxide such as (e.g., SiO x or AlO x coated PET film).

[0086] One or more layers of the laminate may comprise a metal film or foil, such as aluminum foil, which preferably has a thickness of about 5 to 100 μm.

[0087] The individual films comprising the laminate can be prepared in a wide variety of thicknesses, for example, from about 5 to about 200 microns. The films, foils, and laminating adhesive compositions can be assembled into a laminate by any one or more of several conventional procedures known in the art for such purposes. For example, the adhesive formulation may be applied to one or both surfaces of two films / foils by means of extrusion, brush, roller, blade, spray, or the like, and the film / foil surfaces bearing the adhesive composition are then brought together and passed through a set of rollers (often referred to as nip rollers) that press the films / foils bearing the adhesive composition between them together. The resulting laminate is then wound into a roll or reel for aging. The adhesive may be applied by conventional techniques, such as a 3 / 4 roller application mechanism for solventless systems or a 2-roller application mechanism for solvent-based systems.

[0088] The coating weight of the adhesive formulation that can be applied to the surface of the film layer is from about 0.1 to about 10 g / m 2 , more typically about 2.0 to about 6.0 g / m 2 The range is.

[0089] The laminate prepared according to the present disclosure may be used for packaging purposes in the same manner as conventional or known flexible laminate packaging films. The laminate is particularly suitable for forming flexible pouch-like containers into which food products can be filled and sealed. For example, two rectangular or square sheets of the laminate may be stacked in a desired configuration or arrangement; preferably, the two layers of the two opposing sheets can be heat-sealed to each other. The three perimeters of the stacked assembly are then heat-sealed to form a pouch. Heat sealing can be easily accomplished using a heating bar, heating knife, heating wire, impulse sealer, ultrasonic sealer, or induction sealer.

[0090] The food product is then packed into the pouch so formed. If necessary, gases harmful to the food, such as air, are removed by known means such as vacuum degassing, hot packing, boiling degassing, or steam injection or deformation of the container. The opening of the pouch is then heat sealed. The packaged pouch may later be heated.

[0091] One embodiment of the food packaging material according to the present invention is illustrated in FIG. 1, but the present invention is not limited to these embodiments. FIG. 1 shows a cross-sectional view of a food packaging film 10. This food packaging film 10 is a laminate including one metal foil 14 and two plastic films 12 and 13, with the plastic films 12 and 13 attached to both sides of the metal foil 14 using adhesive layers 11. More specifically, the plastic film 12 is preferably, for example, a polyethylene terephthalate (PET) film, and the film 13 is preferably a polyolefin film, more preferably a PE film. The metal foil 14 is inserted between them. The metal foil 14 may be, for example, an aluminum foil. The film 12 is adhered to the metal foil 14, and the film 13 is adhered to the metal foil 14, respectively, using adhesive layers 11 for food packaging films. Examples of films to be laminated include plastic films made from polyethylene terephthalate, nylon, polyethylene, polypropylene, polyvinyl chloride, etc.; metal foils such as aluminum foil; vapor-deposited films such as metal vapor-deposited films and silica vapor-deposited films; and metal films made from stainless steel, steel, copper, and lead. Furthermore, the thickness of the film to be laminated, for example, the plastic film, is preferably within the range of 5 to 200 μm.

[0092] The present invention will be explained in more detail by the following examples, but these examples should not be construed as limiting the concept of the present invention. [Example]

[0093] The following materials were used in the examples: The diacid is a mixture of adipic, isophthalic, terephthalic, and azelaic acids and is commercially available from Sigma-Aldrich. The diol is a mixture of diethylene glycol (SABIC) and 1,2-propanediol (BASF). 1,4-Cyclohexanedimethanol (CHDM) was obtained from Eastman under the trade name Eastman CHDM-D. Isosorbide was obtained from Rockete under the trade name POLYSORB PA. Ethyl acetate was obtained from Brenntag. 1,6-Hexamethylene diisocyanate (HDI) trimer was obtained from Covestro under the trade name Desmodur N 3300. Bis[γ-(triethoxysilyl)propyl]amine (bis-AMEO) was obtained from Evonik under the trade name Dynasylan 1122. Bis[γ-(trimethoxysilyl)propyl]amine (bis-AMMO) was obtained from Evonik under the trade name Dynasylan 1124. Loctite Liofol LA 6707 is a difunctional polypropylene glycol available from Henkel.

[0094] <Solvent-free two-component adhesive composition> [Preparation of polyester polyol] The polyester polyols were prepared according to the formulations in Table 1.

[0095] All ingredients listed in Table 1 were weighed into a flask and nitrogen was added. The heater was set to 220°C, and the condensation reaction proceeded, followed by the production of water. The reaction was monitored by acid value. When the acid value measured was less than 2 mg KOH / g, the reaction was terminated and the product was obtained. The polyester polyol was cooled and filled into a suitable glass container, after which the OH value was measured to determine the final specifications. Polyester polyol 7 was solid even at the reaction temperature and therefore not suitable for further processing. The other polyester polyols prepared were liquid at room temperature and suitable for formulation into adhesive compositions.

[0096] [Table 1]

[0097] <Isocyanate component 1:> Approximately 90-95 parts by weight of HDI trimer was weighed into a flask. The isocyanate was heated to 40°C and stirred. Within 1 hour, approximately 5-10 parts by weight of Bis-AMMO was carefully added in one portion. The temperature was monitored consistently and cooled with water as needed to prevent the temperature from exceeding 80°C. Once the aminosilane addition was complete, the mixture was stirred for an additional 30 minutes to yield the isocyanate component. The NCO value was measured as approximately 20%.

[0098] <Isocyanate component 2:> Approximately 90-95 parts by weight of HDI trimer was weighed into a flask. The isocyanate was heated to a maximum of 40°C and stirred. Within 1 hour, approximately 5-10 parts by weight of Bis-AMEO were carefully added in one portion. The temperature was consistently monitored and cooled with water as needed to prevent the temperature from exceeding 80°C. Once the aminosilane addition was complete, the mixture was stirred for an additional 30 minutes to yield the isocyanate component. The NCO value was measured as approximately 19%.

[0099] <Isocyanate component 3:> Approximately 90-95 parts by weight of HDI trimer was weighed into a flask. The isocyanate was heated to a maximum of 40°C and stirred. Within 1 hour, approximately 5-10 parts by weight of Bis-AMMO was carefully added in two portions. The temperature was consistently monitored and cooled with water as needed to prevent the temperature from exceeding 80°C. Once the aminosilane addition was complete, the mixture was stirred for an additional 30 minutes to yield the isocyanate component. The NCO value was measured to be approximately 18%.

[0100] <Examples 1 to 5 (Ex. 1 to Ex. 5) and Comparative Examples 1 to 3 (CEx. 1 to 3)> The adhesive systems for food packaging films of Examples 1 to 5 and Comparative Examples 1 to 3 were prepared by mixing the components in ethyl acetate according to the formulations shown in Table 2.

[0101] [Table 2]

[0102] The adhesive system for food packaging films and the evaluation test samples were prepared as follows.

[0103] Each of the polyester polyols according to the invention was converted into a laminating adhesive together with an isocyanate component, with a constant NCO / OH addition ratio being chosen.

[0104] The substrate to be coated was formatted in DIN A4 size. PET / aluminum carrier double-sided foil was coated at 4 g / m 2 The coated carrier film was then dried in a drying oven at 90°C for 1 minute. A polyethylene film was then pressed onto the coated surface. The composite thus produced was cured in a drying oven at 40°C under pressure (8 kg load) between metal plates.

[0105] <One-component adhesive composition> [Examples 6 to 8 and Comparative Examples 4 and 5] The adhesive compositions for food packaging films of Examples 6 to 8 and Comparative Examples 4 and 5 were produced by mixing the respective components according to the formulations in Table 3.

[0106] [Table 3]

[0107] The one-component adhesive system was prepared by (1) chain-extending HDI trimer with polyester polyol and (2) adding bis-AMMO to the reaction product of step (1) to obtain a reactive polyurethane prepolymer as the one-component adhesive system.

[0108] Adhesive systems for food packaging films and evaluation test samples were prepared as follows.

[0109] The substrate to be coated was formatted in DIN A4 size. PET / aluminum carrier double-sided foil was coated at 4 g / m 2The adhesive mixture was coated onto the coated carrier film. The coated carrier film was dried in a drying oven at 90°C for 1 minute. A polyethylene film was then pressed onto the coated surface. The composite thus produced was cured in a drying oven at 40°C under pressure (8 kg load) between metal plates.

[0110] The resulting one-component and two-component adhesive systems for food packaging films were evaluated using the following test procedures, and the test results are shown in Tables 4 and 5.

[0111] <Adhesive strength after storage at 40°C for 7 days> The laminates were prepared and stored at 40° C. for 7 days before measuring the adhesive strength of the adhesive system according to DIN 53357.

[0112] <Adhesive strength after storage at 40°C for 7 days and sterilization> After preparing the laminates and storing them at 40° C. for 7 days, the laminates were sterilized for 30 minutes at 131° C. Immediately after the sterilization treatment, the bond strength of the adhesive was measured according to DIN 53357.

[0113] <Adhesive strength after storage at 40°C for 7 days and sterilization with oleic acid> After preparing the laminates and storing them at 40°C for 7 days, pouches were made from the laminates and filled with an aqueous starch emulsion containing up to 0.1% oleic acid. The pouches were sterilized at 131°C for 30 minutes. Immediately after sterilization, the pouches were emptied and the adhesive bond strength was measured according to DIN 53357.

[0114] [Table 4]

[0115] [Table 5]

[0116] As can be seen from Tables 4 and 5, the one-component and two-component adhesive systems of the inventive examples exhibited excellent adhesive strength even after treatment under harsh conditions, whereas the comparative examples using polyol or isocyanate components not according to the invention exhibited poor adhesive strength or even poor adhesion under harsh conditions. The initial disclosure of this specification encompasses at least the following aspects. [1] Based on the total weight of the reaction mixture 1 to 25 wt. % of at least one cycloaliphatic polyol; 1 to 40 wt. % of at least one heterocyclic polyol; 1 to 40 wt. % of at least one linear or branched aliphatic polyol, and 30 to 70 wt. % of at least one multifunctional carboxylic acid; a polyol component comprising at least one polyester polyol obtained from a reaction mixture comprising: an isocyanate component comprising a combination of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups, and / or a reaction product of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups; 1. A polyurethane adhesive composition comprising: [2] The polyurethane adhesive composition according to [1] above, wherein the alicyclic polyol has one or more rings and is preferably selected from 1,4-cyclohexanedimethanol, cyclobutanediol, cyclopentanediol, 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, cyclohexanedimethanol, tricyclo[5.2.1.0.2.6]decanedimethanol, bicyclo[4.3.0]nonanediol, dicyclohexanediol, tricyclo[5.3.1.1]dodecanediol, bicyclo[4.3.0]nonanedimethanol, tricyclo[5.3.1.1]dodecanediethanol, spiro[3.4]octanediol, butylcyclohexanediol, 1,1'-bicyclohexylidenediol, cyclohexanetriol, hydrogenated bisphenol A, and 1,3-adamantanediol. [3] The polyurethane adhesive composition according to [1] or [2], wherein the heterocyclic polyol is selected from 1,4:3,6-dianhydrohexitol, spiroglycol, 2,4:3,5-di-O-methylenemannitol, and 2,3:4,5-di-O-methylene lactose, and is preferably isosorbide. [4] The polyurethane adhesive composition according to any one of [1] to [3] above, wherein the aliphatic or alicyclic isocyanate-functionalized compound is selected from 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylyl diisocyanate (XDI), adducts thereof, oligomers thereof, and mixtures thereof. [5] The polyurethane adhesive composition according to any one of [1] to [4] above, wherein the hydrolyzable alkoxysilane compound having no epoxide group contains a functional group reactive with an isocyanate group, preferably a hydroxyl group, a thiol group, a carboxyl group, a primary and secondary amino group, or a mixture thereof, more preferably a carboxyl group, a primary and secondary amino group, or a mixture thereof, particularly preferably a primary and secondary amino group. [6] Hydrolyzable alkoxysilane compounds without epoxide groups include α-aminomethyltrimethoxysilane, α-aminomethylmethyldimethoxysilane, α-aminomethyldimethylmethoxysilane, α-aminomethyltriethoxysilane, α-aminomethylmethyldiethoxysilane, α-aminomethyldimethylethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropyldimethylmethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyldimethylethoxysilane, N-2(aminoethyl)α-aminomethyltrimethoxysilane, N-2(aminoethyl)α-aminomethylmethyldimethoxysilane, and N-2(aminoethyl)α-aminomethyldimethyl

[0023] The polyurethane adhesive composition according to any one of [1] to [5] above, wherein the hydroxyl group is selected from N-2(aminoethyl)α-aminomethyltriethoxysilane, N-2(aminoethyl)α-aminomethylmethyldiethoxysilane, N-2(aminoethyl)α-aminomethyldimethylethoxysilane, bis-(trimethoxysilylpropyl)amine, bis-(methyldimethoxysilylpropyl)amine, bis-(dimethylmethoxysilylpropyl)amine, bis-(triethoxysilylpropyl)amine, bis-(methyldiethoxysilylpropyl)amine, bis-(dimethylethoxysilylpropyl)amine, and mixtures thereof, preferably selected from bis-(trimethoxysilylpropyl)amine and / or bis-(methyldimethoxysilylpropyl)amine. [7] The polyurethane adhesive composition according to any one of the above [1] to [6], wherein the weight ratio of the polyol component to the isocyanate component is 15:1 to 1:5. [8] A two-component or multi-component polyurethane adhesive system comprising the polyurethane adhesive composition according to any one of [1] to [7] above. [9] A one-component, two-component or multi-component polyurethane adhesive system comprising a polyurethane prepolymer that is a reaction product of the polyurethane adhesive composition according to any one of [1] to [8] above.

[10] The polyurethane adhesive system according to [8] or [9], wherein the polyurethane adhesive system contains at least one solvent or does not contain a solvent.

[11] The cured adhesive according to any one of [8] to

[10] above, which has an adhesive strength of 3 N / 15 mm or more, preferably 4 N / 15 mm or more according to DIN 53357, after storage at 40°C for 7 days.

[12] The cured adhesive according to any one of [8] to

[11] above, which has an adhesive strength of 5 N / 15 mm or more, preferably 6 N / 15 mm or more, according to DIN 53357, after hard storage at 40°C for 7 days and sterilization at 131°C for 30 minutes.

[13] The cured adhesive according to any one of [8] to

[12] above, which has an adhesive strength of 5 N / 15 mm or more, preferably 6 N / 15 mm or more, according to DIN 53357, after storage at 40°C for 7 days and sterilization using oleic acid at 131°C for 30 minutes.

[14] A flexible packaging material comprising: a first layer comprising a first polyolefin or a first polyester; a second layer comprising a second polyolefin which may be the same as or different from the first polyolefin, a second polyester which may be the same as or different from the first polyester, or a metal foil; and the cured adhesive according to any one of

[11] to

[13] above, which bonds the first layer and the second layer.

[15] A method for producing a flexible film laminate, comprising: combining the components of the polyurethane adhesive composition described in [1] above in a predetermined weight ratio to form an adhesive mixture; disposing an adhesive mixture on at least a portion of one surface of a first flexible film; joining a first flexible film and a second flexible film, wherein the adhesive mixture is interposed between the first flexible film and the second flexible film; and Curing the adhesive mixture A method comprising:

Claims

1. Based on the total weight of the reaction mixture, 1 to 25 wt. % of at least one cycloaliphatic polyol; 1 to 40 wt. % of at least one heterocyclic polyol; 1 to 40 wt. % of at least one linear or branched aliphatic polyol, and 30 to 70% by weight of at least one multifunctional carboxylic acid; a polyol component comprising at least one polyester polyol obtained from a reaction mixture comprising: an isocyanate component comprising a combination of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups, and / or a reaction product of at least one aliphatic or cycloaliphatic isocyanate-functionalized compound and at least one hydrolyzable alkoxysilane compound having no epoxide groups; 1. A polyurethane adhesive composition comprising:

2. 2. The polyurethane adhesive composition of claim 1, wherein the alicyclic polyol has one or more rings and is selected from 1,4-cyclohexanedimethanol, cyclobutanediol, cyclopentanediol, 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, cyclohexanedimethanol, tricyclo[5.2.1.0.2.6]decanedimethanol, bicyclo[4.3.0]nonanediol, dicyclohexanediol, tricyclo[5.3.1.1]dodecanediol, bicyclo[4.3.0]nonanedimethanol, tricyclo[5.3.1.1]dodecanediethanol, spiro[3.4]octanediol, butylcyclohexanediol, 1,1'-bicyclohexylidenediol, cyclohexanetriol, hydrogenated bisphenol A, and 1,3-adamantanediol.

3. 3. The polyurethane adhesive composition of claim 1, wherein the heterocyclic polyol is selected from 1,4:3,6-dianhydrohexitol, spiroglycol, 2,4:3,5-di-O-methylenemannitol, and 2,3:4,5-di-O-methylene lactose.

4. 4. The polyurethane adhesive composition according to claim 1, wherein the aliphatic or cycloaliphatic isocyanate-functionalized compound is selected from 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylyl diisocyanate (XDI), adducts thereof, oligomers thereof, and mixtures thereof.

5. 5. The polyurethane adhesive composition according to claim 1, wherein the hydrolyzable alkoxysilane compound having no epoxide group contains a functional group reactive with an isocyanate group.

6. Examples of hydrolyzable alkoxysilane compounds having no epoxide group include α-aminomethyltrimethoxysilane, α-aminomethylmethyldimethoxysilane, α-aminomethyldimethylmethoxysilane, α-aminomethyltriethoxysilane, α-aminomethylmethyldiethoxysilane, α-aminomethyldimethylethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropyldimethylmethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyldimethylethoxysilane, N-2(aminoethyl)α-aminomethyltrimethoxysilane, N-2(aminoethyl)α-aminomethylmethyl 6. The polyurethane adhesive composition of claim 1, wherein the hydroxyl group is selected from N-2(aminoethyl)α-aminomethyldimethylmethoxysilane, N-2(aminoethyl)α-aminomethyltriethoxysilane, N-2(aminoethyl)α-aminomethylmethyldiethoxysilane, N-2(aminoethyl)α-aminomethyldimethylethoxysilane, bis-(trimethoxysilylpropyl)amine, bis-(methyldimethoxysilylpropyl)amine, bis-(dimethylmethoxysilylpropyl)amine, bis-(triethoxysilylpropyl)amine, bis-(methyldiethoxysilylpropyl)amine, bis-(dimethylethoxysilylpropyl)amine, and mixtures thereof.

7. 7. The polyurethane adhesive composition according to claim 1, wherein the weight ratio of the polyol component to the isocyanate component is from 15:1 to 1:

5.

8. A two-component or multi-component polyurethane adhesive system comprising the polyurethane adhesive composition of any one of claims 1 to 7.

9. A one-component, two-component or multi-component polyurethane adhesive system comprising a polyurethane prepolymer that is the reaction product of the polyurethane adhesive composition of any of claims 1-8.

10. 10. The polyurethane adhesive system of claim 8 or 9, wherein the polyurethane adhesive system comprises at least one solvent or is solvent-free.

11. 11. The cured adhesive of any one of claims 8 to 10, having an adhesive strength according to DIN 53357 of 3 N / 15 mm or greater after storage at 40°C for 7 days.

12. 12. The cured adhesive of any one of claims 8 to 11, having an adhesive strength of at least 5 N / 15 mm according to DIN 53357 after hard storage at 40°C for 7 days and sterilization at 131°C for 30 minutes.

13. 13. The cured adhesive of any one of claims 8 to 12, having an adhesive strength of at least 5 N / 15 mm according to DIN 53357 after storage at 40°C for 7 days and sterilization with oleic acid at 131°C for 30 minutes.

14. 14. A flexible packaging material comprising: a first layer comprising a first polyolefin or a first polyester; a second layer comprising a second polyolefin which may be the same as or different from the first polyolefin, a second polyester which may be the same as or different from the first polyester, or a metal foil; and the cured adhesive according to any one of claims 11 to 13 which bonds the first layer and the second layer.

15. 1. A method for making a flexible film laminate, comprising: combining the components of the polyurethane adhesive composition of claim 1 in predetermined weight ratios to form an adhesive mixture; disposing an adhesive mixture on at least a portion of one surface of a first flexible film; joining a first flexible film and a second flexible film, wherein the adhesive mixture is interposed between the first flexible film and the second flexible film; and Curing the adhesive mixture A method comprising:

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