Solventless polyurethane adhesive composition and its use

Abstract

The solventless polyurethane adhesive composition is obtained by reacting a reaction mixture containing (a) at least one polyester polyol obtained by reacting (i) at least one polycarboxylic acid selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid, (ii) neopentyl glycol, and (iii) at least one polyol having a weight average molecular weight of 50 to 300 g / mol other than neopentyl glycol, and (b) a polyol mixture containing at least one polyether polyol having a weight average molecular weight of 200 to 4000 g / mol with a stoichiometric excess of at least one polyisocyanate, and is composed of (A) at least one isocyanate group-containing component containing at least one isocyanate-terminated polyurethane prepolymer, and (B) at least one hydroxyl group-containing component, and the isocyanate-containing component (A) has an NCO content of more than 10% by weight and less than 14% by weight.

Description

Technical Field

[0001] The present invention relates to a solvent-free polyurethane adhesive composition and its use. In particular, the present invention relates to a solvent-free polyurethane adhesive composition for laminating PET and aluminum foil in food packaging.

Background Art

[0002] Film-to-film and film-to-foil laminates are used in the packaging of a variety of foods and other industrial products. Since it is often difficult to achieve satisfactory adhesion of films with different compositions in coextrusion and heat welding technologies, adhesives and coatings are used in the manufacture of these composite structures. This type of laminate needs to have many important performance characteristics so that the packaged goods can be safely placed, transported, and stored until the customer uses them. At many stages of packaging, the laminate is exposed to various processes such as printing, pouch forming, bag making, filling, boxing, and transportation. For over 20 years, preparations based on polyurethanes, mainly produced by the reaction of polyols and polyisocyanates, have been used. These products were mainly solvent solutions of aromatic isocyanates such as MDI (diphenylmethane diisocyanate) and TDI (toluene diisocyanate), and polyester and polyether polyols appropriately reacted with many reaction products of diisocyanates. Due to the increasing environmental awareness, such solvent solutions have been replaced by solvent-free polyurethanes in most applications. Several types of aqueous laminating adhesives are known, but most are provided as 100% solids systems. These systems are essentially similar to solvent-containing products but contain a significant amount of free monomeric isocyanates. Their volatility, the health effects of such isocyanates, and the reaction products with atmospheric moisture that cause the formation of aromatic diamines have been a concern, especially in food packaging. Most of the adhesives and coatings used in the industry are based on polyurethanes. When laminating films that are considered high barriers in the sense of not allowing gases to pass freely, such free isocyanate-containing adhesives cause appearance problems. Trace amounts of moisture present on the film surface react with the isocyanate in a well-known reaction to form carbamic acid. This unstable acid releases carbon dioxide gas. Due to the impermeability of the film, the carbon dioxide gas is trapped as bubbles, causing appearance problems.

[0003] U.S. Patent Application Publication No. 2019 / 0127616 discloses a solventless adhesive comprising an isocyanate component containing at least one isocyanate prepolymer that is a reaction product of reactants including at least one isocyanate, at least one polyol, and a branched alkanediol, and a polyol component containing at least one polyol and a branched alkanediol. The branched alkanediol can include a monoalkyl chain such as 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, and combinations thereof. During boiling inside the bag, the pouch formed of a laminated film after being immersed in water showed a good appearance without the tunneling phenomenon.

[0004] European Patent Application Publication No. 3947588 discloses a solventless adhesive composition comprising an isocyanate prepolymer having a side chain represented by (A)-R2-(O-R1-O) n -R3 and (B) an isocyanate-reactive component, which shows improved adhesion strength, heat seal strength, adhesive friction coefficient characteristics, and optical appearance in a PET ink / MPET laminate.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] None of the above prior arts disclose a solventless adhesive composition that exhibits a desirable low viscosity and a satisfactory optical appearance, particularly on PET and aluminum foil. Therefore, there is a need in the art for a solventless polyurethane adhesive composition that has a desired low viscosity and exhibits a satisfactory optical appearance when laminated on a film or foil, particularly on PET / aluminum foil.

Means for Solving the Problems

[0007] Disclosed herein is (a)(i) at least one polyester polyol obtained by reacting a reaction mixture comprising at least one polycarboxylic acid selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid, (ii) neopentyl glycol, and (iii) at least one polyol having a weight average molecular weight of 50 to 300 g / mol other than neopentyl glycol, and (b) at least one polyether polyol having a weight average molecular weight of 200 to 4000 g / mol A polyol mixture containing is reacted with a stoichiometric excess of at least one polyisocyanate to obtain (A) at least one isocyanate group-containing component containing at least one isocyanate-terminated polyurethane prepolymer, and (B) at least one hydroxyl group-containing component containing, A solventless polyurethane adhesive composition, wherein the isocyanate-containing component (A) has an NCO content of more than 10% by weight and less than 14% by weight.

[0008] Also, herein A laminate including a first layer, a second layer, and an adhesive layer sandwiched therebetween, wherein the first layer and the second layer are each independently selected from films made of PET (polyethylene glycol terephthalate), PP (polypropylene), OPP (oriented polypropylene), CPP (cast polypropylene), BOPP (biaxially oriented polypropylene), PE (polyethylene), aluminum foil, PA (polyamide), VMPET (vacuum-deposited polyethylene glycol terephthalate), and VMCPP (vacuum-deposited cast polypropylene), preferably PET (polyethylene glycol terephthalate) and aluminum foil, and the adhesive layer is formed by curing the adhesive composition of the present invention is also disclosed.

[0009] Furthermore, disclosed herein is a food pouch formed by the laminate of the present invention.

[0010] Furthermore, disclosed herein is the use of the solvent-free polyurethane adhesive composition of the present invention or the laminate of the present invention in the manufacture of food packaging.

[0011] Other features and aspects of the subject matter are described in more detail below.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0013] Those skilled in the art will understand that this description is merely illustrative of exemplary embodiments and is not intended to limit broader aspects of the present invention.

[0014] Unless otherwise specified, in the context of the present invention, the terms used shall be construed according to the following definitions.

[0015] Unless otherwise specified, as used herein, the terms "a", "an", and "the" include both singular and plural forms.

[0016] As used herein, the term "composition" refers to a mixture of materials that make up the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0017] As used herein, the terms "comprising" and "comprises" are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, unrecited members, elements, or process steps.

[0018] As used herein, the term "at least one" or "one or more" used to define a component refers to the type of component and not the absolute number of molecules. For example, "one or more polyols" means one type of polyol or a mixture of multiple different types of polyols.

[0019] As used herein, the term "room temperature" refers to a temperature of about 20°C to about 25°C, preferably about 25°C.

[0020] As used herein, the term "polyol" should be understood as a molecule having two or more hydroxyl groups, regardless of whether the molecule contains other functional groups. However, the polyols useful in the present invention preferably contain only OH groups, or, if other functional groups are present, none of these other functional groups react with isocyanate at least under the conditions of the present invention.

[0021] Unless otherwise specified, the description of numerical endpoints includes not only the recited endpoints but also all numbers and fractions included within each range.

[0022] Unless otherwise specified, the molecular weight refers to the weight average molecular weight (Mw). Unless otherwise specified, all molecular weight data refer to values obtained by gel permeation chromatography (GPC) in accordance with, for example, DIN 55672.

[0023] Unless otherwise defined, all terms (including technical and scientific terms) used in the present invention have the meanings commonly understood by a person of ordinary skill in the art to which this invention belongs.

[0024] According to a first aspect of the present invention, disclosed herein is (a) (i) at least one polycarboxylic acid selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid, (ii) neopentyl glycol, and (iii) at least one polyester polyol obtained by reacting a reaction mixture containing at least one polyol having a weight average molecular weight of 50 to 300 g / mol other than neopentyl glycol, and (b) at least one polyether polyol having a weight average molecular weight of 200 to 4000 g / mol A polyol mixture containing and a stoichiometric excess of at least one polyisocyanate are reacted to obtain (A) at least one isocyanate group-containing component containing at least one isocyanate-terminated polyurethane prepolymer, and (B) at least one hydroxyl group-containing component A solvent-free polyurethane adhesive composition comprising, The isocyanate-containing component (A) has an NCO content of more than 10% by weight and less than 14% by weight.

[0025] <(A) Isocyanate group-containing component> According to the present invention, (A) at least one isocyanate group (NCO)-containing component is (a) (i) At least one polycarboxylic acid selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid, (ii) neopentyl glycol, and (iii) at least one polyol having a weight average molecular weight of 50 to 300 g / mol other than neopentyl glycol. At least one polyester polyol obtained by reacting a reaction mixture containing, and (b) at least one polyether polyol having a weight average molecular weight of 200 to 4000 g / mol, and a stoichiometric excess of at least one polyisocyanate. It contains at least one isocyanate group (NCO)-terminated polyurethane prepolymer obtained by reacting.

[0026] Preferably, the NCO-terminated polyurethane prepolymer useful in the present invention has a weight average molecular weight (Mw) in the range of 200 to 100,000 g / mol, more preferably 500 to 5,000 g / mol.

[0027] Preferably, at least one NCO-terminated polyurethane prepolymer constitutes 5 to 95%, preferably 30 to 60% of the total weight of the adhesive composition.

[0028] ((a) Polyester polyol) According to the present invention, a suitable polyester polyol in the present invention is obtained by reacting a reaction mixture containing (i) at least one polycarboxylic acid selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid, (ii) neopentyl glycol, and (iii) at least one polyol having a weight average molecular weight of 50 to 300 g / mol other than neopentyl glycol. By using neopentyl glycol selected for the preparation of the polyester polyol, a polyurethane adhesive composition having good optical appearance when laminated and cured can be produced.

[0029] In a preferred embodiment, the reaction mixture contains at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid.

[0030] Specific examples of suitable aliphatic dicarboxylic acids as component (i) are selected from malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, dimer acid, and combinations thereof, preferably adipic acid, sebacic acid, succinic acid, their corresponding polycarboxylic anhydrides, and combinations thereof, C2-C aliphatic dicarboxylic acids that can be 36 an aliphatic dicarboxylic acid.

[0031] Specific examples of suitable aromatic dicarboxylic acids as component (i) are selected from isophthalic acid, terephthalic acid, diphenic acid, 2,6-naphthalenedicarboxylic acid, their corresponding polycarboxylic anhydrides, and combinations thereof, preferably isophthalic acid, terephthalic acid, their corresponding polycarboxylic anhydrides, and combinations thereof, C8- aromatic dicarboxylic acids that can be 20 an aromatic dicarboxylic acid.

[0032] As the component (iii), specific examples of suitable polyols other than neopentyl glycol having a weight average molecular weight of 50 to 300 g / mol include ethylene glycol, diethylene glycol, 1,2-butanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, glycerol, trimethylolpropane, 1,2-propylene glycol, dipropylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, 2-butyl-2-ethylpropanediol, pentaerythritol, polytetramethylene ether glycol, and combinations thereof, and preferably can be selected from ethylene glycol, diethylene glycol, 1,2-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, and combinations thereof.

[0033] The polyester polyol prepared by polycondensation of the neopentyl glycol (ii) of the present invention and at least one polyol (iii) having a weight average molecular weight of 50 to 300 g / mol other than the neopentyl glycol of the present invention can be used together with at least one polycarboxylic acid (i) in a stoichiometric excess selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid of the present invention. The above polycarboxylic acid can be used alone or as a mixture of two or more.

[0034] A suitable method for preparing the polyester polyol useful in the present invention includes the following steps: (i) mixing a polycarboxylic acid, neopentyl glycol, and the above other polyols at a temperature of 120 to 250°C for 6 to 12 hours while protecting with a nitrogen stream to ensure polycondensation occurs; (ii) applying a vacuum of 50 to 900 mBar for 1 to 12 hours in the latter half of the reaction to improve the molecular weight of the obtained polyester polyol.

[0035] Preferably, the polyester polyol useful in the present invention has a weight average molecular weight (Mw) in the range of 450 to 2,000 g / mol, more preferably 800 to 1500 g / mol.

[0036] In some embodiments, useful polyester polyols can be modified with vegetable oils selected from castor oil, soybean oil, palm oil, coconut oil, and combinations thereof. When using a polyester polyol modified with a vegetable oil, the vegetable oil is preferably in an amount of 5% or less by weight of the adhesive composition. The preferred adhesive compositions of the present invention do not contain any vegetable oils.

[0037] Commercially available products can also be used in the present invention. Examples thereof include PES 5622, PES 9000 manufactured by Henkel, CP-2070 manufactured by Nanjing CSD, and ES-980 manufactured by SKC.

[0038] Particularly preferably, the polyester polyol used to prepare component (A) can be present in an amount of 5% to 30% by weight, more preferably 10% to 25% by weight, based on the weight of component (A).

[0039] ((b) Polyether polyol) According to the present invention, at least one polyether polyol having a weight average molecular weight of 200 to 4000 g / mol is included for preparing component (A) used in the composition of the present invention.

[0040] The polyether polyols used to prepare component (A) in the present invention are well known to those skilled in the art. These polyether polyols are obtained by copolymerizing at least one compound such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, etc. with at least one compound having an average of at least 2 active hydrogen atoms in one molecule, such as ethylene glycol, propylene glycol, dipropylene glycol, glycerol, and combinations thereof, and the like. Other suitable polyhydric compounds include sucrose, ethylenediamine, propylenediamine, triethanolamine, 1,2-propanedithiol, and combinations thereof.

[0041] Preferred polyether polyols used in the preparation of component (A) can be selected from polytetramethylene ether glycol, poly(oxypropylene) glycol, polyethylene oxide, polybutylene oxide, and ethylene oxide end-capped types of any of the foregoing, and combinations thereof. The most preferred polyether polyols are polytetramethylene ether glycol, poly(oxypropylene) glycol, ethylene oxide end-capped poly(oxypropylene) glycol, and combinations thereof.

[0042] In a preferred embodiment, the polyether polyol has an average molecular weight (Mw) of 450 to 2,000 g / mol.

[0043] Commercially available products can be used in the present invention. Examples thereof include DP 450, DP 1000M, and DP2000M manufactured by Kukudo Chemical.

[0044] Particularly preferably, the polyether polyol may be present in an amount of 10% to 50% by weight, more preferably 20% to 40% by weight, based on the weight of component (A).

[0045] (Polyisocyanate) According to the present invention, component (A) of the present invention contains at least one NCO-terminated polyurethane prepolymer obtained by reacting the above polyol mixture with a stoichiometric excess of at least one polyisocyanate.

[0046] As used herein, the term "polyisocyanate" is preferably understood to have 2 to 4 isocyanate groups per molecule. Preferably, the polyisocyanate is a diisocyanate such as an aliphatic, alicyclic, aromatic diisocyanate.

[0047] In one embodiment, the aromatic diisocyanate can be selected from 2,2'-methylenediphenyldiisocyanate (MDI), 4,4'-methylenediphenyldiisocyanate, 2,4'-methylenediphenyldiisocyanate, 2,4-toluenediisocyanate (TDI), 2,6-toluenediisocyanate, 1,3-phenylenediisocyanate (PDI), 1,4-phenylenediisocyanate, 1,4-naphthylenediisocyanate (NDI), 1,5-naphthylenediisocyanate, tetramethylxylylene diisocyanate (TMXDI), 4,4'-dibenzyl diisocyanate, xylylene diisocyanate (XDI), and combinations thereof.

[0048] In one embodiment, the aliphatic isocyanate can be selected from butane-1,4-diisocyanate, 1,6-hexamethylene diisocyanate (HMDI), 1,6-diisocyanato-2,2,4-trimethylhexane, 1,12-diisocyanato-dodecane, and combinations thereof.

[0049] In one embodiment, the cycloaliphatic isocyanate can be selected from isophorone diisocyanate (IPDI), 4,4-dicyclohexylmethane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexene diisocyanate, 1-methyl-2,4-diisocyanato-cyclohexane, and combinations thereof.

[0050] Preferably, the polyisocyanate can be selected from 2,2'-methylenediphenyldiisocyanate, 4,4'-methylenediphenyldiisocyanate, 2,4'-methylenediphenyldiisocyanate, 2,4-toluenediisocyanate, 1,6-hexamethylene diisocyanate, and combinations thereof. More preferably, MDI is used as the polyisocyanate.

[0051] In the present invention, commercially available products can be used. Examples thereof include Desmodur 44C FUSED, Desmodur 0118I, Desmodur 44M manufactured by Covestro, Vannate MDI 100F manufactured by Wanhua Chemicals, and Supresec 1809 manufactured by HUNTSMAN.

[0052] Particularly preferably, the polyisocyanate may be present in an amount of 40% to 85% by weight, more preferably 55% to 80% by weight, based on the weight of component (A).

[0053] The above-mentioned polyisocyanate to stoichiometric excess polyol mixture is particularly greater than 1:1 to 50:1, preferably 2:1 to 10:1, with respect to the molar ratio of NCO groups to OH groups in the NCO-containing component (A). Since an excess amount of isocyanate is used, the NCO-terminated polyurethane prepolymer usually contains a certain amount of isocyanate monomer. In order to achieve the desired effects of the present invention, the NCO-containing component (A) has an NCO content of more than 10% to less than 14%. If the NCO content is outside the claimed range, the optical appearance of the laminate formed by the adhesive composition will show orange peel, small dots, or bubbles.

[0054] The NCO content based on the isocyanate-containing component (A) can be measured in accordance with ISO 14896 / 3 using acetone as a solvent.

[0055] <(B) Hydroxyl group-containing component> According to the present invention, the component (B) of the solventless polyurethane adhesive composition can be at least one hydroxyl group (OH)-containing component.

[0056] Preferably, the OH-containing component (B) in the present invention has a hydroxyl value in the range of 10 to 1500 mgKOH / g, preferably 56 to 560 mgKOH / g.

[0057] As used herein, the term "hydroxyl value" is defined as the number of milligrams of potassium hydroxide required to neutralize the acetic acid incorporated during the acetylation of 1 gram of the hydroxyl component, and is expressed in milligram units of the mass of potassium hydroxide (KOH) corresponding to the hydroxyl content of 1 gram of the hydroxyl component. In the present invention, the hydroxyl value is measured in accordance with DIN 53240-2.

[0058] Preferably, the OH-containing component (B) in the present invention has an average hydroxyl group functionality of 2 to 5, preferably 2 to 4.

[0059] The viscosity of the OH-containing component (B) is not particularly limited. From the perspective of the end use, the viscosity of the component (B) is preferably in the range of 50 to 20000 mPa·s at 25°C, more preferably in the range of 500 to 10000 mPa·s at 25°C.

[0060] Generally, the OH-containing component (B) can be any commonly used polyol (e.g., polyester polyol, polyether polyol, polyester ether polyol, polycarbonate polyol, and combinations thereof). In some embodiments, the polyols useful for preparing the component (B) include the polyol mixtures used in the preparation of the NCO-terminated polyurethane prepolymer in the component (A).

[0061] Particularly preferably, the OH-containing component (B) can be present in an amount of 5 to 95% by weight, more preferably 10 to 56% by weight, based on the total weight of the adhesive composition.

[0062] <Additive> Optionally, conventional additives may be included, independently of each other, in one or both of the components (A) and (B) without impairing the object of the present invention. Such additives may include those commonly used in the art, such as fillers, colorants, defoamers, etc.

[0063] Examples of fillers include those selected from calcium carbonate, titanium dioxide, carbon black, talc powder, porcelain clay, mica powder, diatomaceous earth, alumina, and combinations thereof.

[0064] Examples of colorants include pigments that can be selected from metal oxide pigments, titanium dioxide, optionally surface-treated zirconium oxide or cerium oxide, zinc oxide, iron oxide (black, yellow or red), chromium oxide, manganese, and combinations thereof.

[0065] Particularly preferably, the additive may be present in an amount of 0 to 5% by weight, preferably 0.01% to 5% by weight, based on the total weight of the adhesive composition.

[0066] <Mixing ratio of component (A) and (B)> In some embodiments, the mixing ratio of the NCO-containing component (A) to the OH-containing component (B) is 5:100 to 19:1 parts by weight, preferably 50:100 to 200:100 parts by weight.

[0067] <Adhesive composition> In a particularly preferred embodiment, the solvent-free polyurethane adhesive composition is based on the total weight of the adhesive composition, (a) (i) at least one polycarboxylic acid selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid, (ii) neopentyl glycol, and (iii) at least one polyester polyol obtained by reacting a reaction mixture containing at least one polyol having a weight average molecular weight of 50 to 300 g / mol other than neopentyl glycol, and (b) at least one polyether polyol having a weight average molecular weight of 200 to 4000 g / mol obtained by reacting a polyol mixture containing with a stoichiometric excess of at least one polyisocyanate, (A) 5 to 95% by weight, preferably 30 to 60% by weight, of at least one NCO-terminated polyurethane prepolymer, and (B) 5 to 95% by weight, preferably 10 to 56% by weight, of at least one OH-containing component, wherein the NCO-containing component (A) has an NCO content of more than 10% by weight and less than 14% by weight.

[0068] In a particularly preferred embodiment, at least one NCO-containing component (A) is (i) at least one polycarboxylic acid selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid, (ii) neopentyl glycol, and (iii) obtained by reacting a reaction mixture containing at least one polyol having a weight average molecular weight of 50 to 300 g / mol other than neopentyl glycol (a) 5% to 30% by weight, more preferably 10% to 25% by weight, of at least one polyester polyol, and (b) 10% to 50% by weight, more preferably 20% to 40% by weight, of at least one polyether polyol having a weight average molecular weight of 200 to 4000 g / mol with a polyol mixture containing 40% to 85% by weight, more preferably 55% to 80% by weight, of at least one polyisocyanate, to obtain at least one NCO-terminated polyurethane prepolymer (the above are all based on the weight of component (A)), wherein the NCO-containing component (A) has an NCO content of more than 10% by weight and less than 14% by weight.

[0069] In some embodiments, the NCO-containing component (A) of the present invention can be prepared by the following steps: (i) Add the polyisocyanate to the reactor at 60°C while protecting with a nitrogen stream; (ii) Introduce the polyol mixture into the reactor, control the water content in the reactor to less than 300 ppm, and then gradually raise the temperature to 80 °C and maintain it for 2 - 3 hours; and (iii) Once the NCO content reaches the required content of the present invention, the produced NCO-containing component (A) can be filled into a container at 60 °C while being protected by a nitrogen stream.

[0070] In some embodiments, the OH-containing component (B) can be obtained directly from commercially available products described herein. In other embodiments, the OH-containing component (B) can be obtained by mixing useful polyols described herein by conventional methods.

[0071] The component (A) and component (B) of the present invention can be mixed before use, and then the uncured adhesive composition can be applied to at least one of the flexible substrates to be adhered, such as films and foils. Then, the flexible substrates are laminated and then cured.

[0072] The devices for these mixing, stirring, dispersion, etc. are not particularly limited. An automatic mortar equipped with a stirrer and a heater, a Henschel mixer, a three-roll mill, a ball mill, a planetary mixer, a bead mill, etc. can be used. Also, these devices can be used in appropriate combinations. The method for preparing the solventless polyurethane adhesive composition is not particularly limited as long as the above components are uniformly mixed.

[0073] <Laminate, food pouch and use> In some embodiments, the solventless polyurethane adhesive composition of the present invention can be cured at 25 °C to 65 °C, preferably at room temperature, for 1 to 7 days.

[0074] As understood, the time and temperature curing profiles of each solventless polyurethane adhesive composition are different, and different compositions can be designed to provide a curing profile suitable for a specific industrial manufacturing process.

[0075] In another aspect of the present invention, a laminate is provided that includes a first layer, a second layer, and an adhesive layer provided therebetween, wherein the first layer and the second layer are each independently made of a film selected from PET (polyethylene glycol terephthalate), PP (polypropylene), OPP (oriented polypropylene), CPP (cast polypropylene), BOPP (biaxially oriented polypropylene), PE (polyethylene), aluminum foil, PA (polyamide), VMPET (vacuum-deposited polyethylene glycol terephthalate), and VMCPP (vacuum-deposited cast polypropylene), preferably PET and aluminum foil, and the adhesive layer is formed by curing the adhesive composition of the present invention.

[0076] A "layer" is a flexible substrate or film (e.g., a flexible layer, i.e., a layer that can be bent by the force of both hands) with one dimension of 0.5 mm or less and the other two dimensions both 1 cm or more.

[0077] The first layer and / or the second layer can be a single material and a single layer, or can also include a plurality of layers of the same or different materials described herein.

[0078] In a particularly preferred embodiment, the solvent-free polyurethane adhesive composition of the present invention is used for laminating PET (polyethylene glycol terephthalate) and aluminum foil.

[0079] Generally, the laminate has a length of 10 to 20,000 meters, 10 to 15,000 meters, preferably 20 to 8,000 meters, and a thickness of 0.1 μm to 0.5 mm, preferably 1 μm to 10 μm. The amount of the adhesive composition is typically about 1 to 5 g.

[0080] A method of forming a laminate using the solventless polyurethane adhesive composition of the present invention is disclosed herein. In some embodiments, the solventless polyurethane adhesive composition is first warmed to a temperature below 45 °C and then applied to the surface of the first layer. The surface of the second layer is then brought into contact with the layer of the adhesive composition to form an uncured laminate. The adhesive composition can be applied by conventional solventless machinery, such as the Super Combi 3000 from Nordmeccanic. The adhesive composition can then be cured or caused to cure. The uncured laminate can be pressured, for example, by passing it through nip rollers which may or may not be heated. The uncured laminate can be heated to promote the curing reaction.

[0081] The processes of the present disclosure can be carried out continuously or batchwise. An example of a continuous process is a roll-to-roll process. The length of the layer is generally from 10 to 20,000 meters, from 10 to 15,000 meters, preferably from 20 to 8,000 meters, and is typically fed at a speed in the range of 0.1 to 60 m / min, preferably 3 to 45 m / min, more preferably 5 to 15 m / min.

[0082] The solventless polyurethane adhesive composition of the present invention can be applied to the layer using any suitable coating method, such as, for example, automatic fine line dispensing, jet dispensing, slot die coating, roll coating, gravure coating, transfer coating, pattern coating, screen printing, spray coating, filament coating, extrusion, air knife, trailing blade, brushing, dipping, doctor blade, offset gravure coating, rotogravure coating, and combinations thereof. The solventless polyurethane adhesive composition can be applied as a continuous or discontinuous coating, in a single or multiple layers, and in combinations thereof.

[0083] The laminate disclosed herein can be cut or shaped into any desired shape suitable for any desired purpose, such as a packaging material.

[0084] In yet another aspect of the present invention, there is provided a food pouch formed from the laminate of the present invention.

[0085] Examples of foods that can be included in such containers include meat, cheese, cereal, nuts, juice, sauce, and the like.

[0086] The above solventless polyurethane adhesive composition and laminate are useful for the production of food containers. Such food containers can be formed using techniques known to those skilled in the art based on the teachings of this specification and based on the specific use of the container (e.g., type of food, amount of food, etc.).

Examples

[0087] The following examples are intended to assist those skilled in the art in better understanding and practicing the present invention. The scope of the present invention is not limited by the examples but is defined by the appended claims. Unless otherwise specified, all parts and percentages are by weight.

[0088] <Raw materials> DP 450 is a polyether polyol having an Mw of 450 g / mol and is available from Kukdo Chemistry. DP 2000 M is a polyether polyol having an Mw of 2000 g / mol and is available from Kukdo Chemistry. Castor oil is available from Ihsedu Agrochem. XCP-355 is a polyester polyol obtained from ethylene glycol, 1,4-butanediol, and adipic acid and is available from Xuchuan Chemical (Suzhou). PES 5622 is a polyester polyol obtained from diethylene glycol, neopentyl glycol, 1,2-butanediol, 2-methyl-1,3-propanediol, sebacic acid, terephthalic acid, and succinic acid and is available from Henkel. PES 9000 is a polyester polyol obtained from monomers selected from ethylene glycol, neopentyl glycol, 1,4 - butanediol, isophthalic acid, adipic acid, and succinic acid, and is available from Henkel. Desmodur 44M is a polyisocyanate available from Covestro. LOCTITE® LIOFOL LA 6011 is a polyol mixture of polyester polyol and polyether polyol, and is available from Henkel.

[0089] <Sample Preparation> The NCO - containing component (A) of the examples and comparative examples was synthesized by the following procedure using the raw materials described in Tables 1 and 2: (i) The polyisocyanate was added to the reactor at 60 °C while protecting it with a nitrogen stream. (ii) The polyol was introduced into the reactor, the water content in the reactor was controlled to less than 300 ppm, and then the temperature was gradually raised to 80 °C and maintained for 2 - 3 hours; and (iii) When the NCO content reached the required content, the produced NCO - containing component (A) was filled into a container at 60 °C while protecting it with a nitrogen stream.

[0090] The NCO - containing component (A) prepared in the examples and comparative examples was mixed with the OH - containing component (B) described in Table 1 or Table 2 to form an adhesive composition.

[0091] Test Method: (Viscosity) The viscosity in the present invention was measured in the temperature range of 50 °C using a 27# spindle and a Brookfield viscometer. A viscosity of less than 10000 cps is acceptable.

[0092] (Optical Appearance) Laminated body samples were prepared using these adhesive compositions with a laminator (Super Combi 3000, available from Nordmeccanic). The adhesive compositions of the examples and comparative examples were warmed to a temperature below 45 °C and applied to PET / aluminum foil (Guoao Foil, Shanghai, China) in a size of 1000 m × 0.7 m. The coating weight was set to form a laminated body sample with a thickness of 1.6 - 1.7 μm.

[0093] The laminated body samples were cured at 45 °C for 48 hours. The optical appearance of the laminated body samples was visually observed and judged based on the following criteria: JPEG2025524712000001.jpg52161

[0094] <Examples of the Invention 1 and Comparative Examples 1 - 3> In this series of examples, one solvent - free polyurethane adhesive composition of the present invention (Example 1) and three compositions (Comparative Examples 1 - 3) having different NCO contents outside the scope of the claims of the present invention were prepared based on the parts by weight specified in Table 1.

[0095]

Table 1

[0096] As can be seen from Table 1 and FIGS. 1 and 2, the compositions of Comparative Examples 1 - 3 having NCO contents outside the scope of the claims of the present invention had insufficient optical appearance or were too viscous to have workability, while the composition of the present invention (Example 1) showed excellent performance.

[0097] <Examples of the Invention 1 - 3 and Comparative Example 4> In this series of examples, the solvent - free polyurethane adhesive compositions of the present invention (Examples 1 - 3) and the composition containing component (A) outside the scope of the claims of the present invention (Comparative Example 4) were prepared based on the parts by weight specified in Table 2.

[0098]

Table 2

[0099] As can be seen from Table 2, the composition (Comparative Example 4) containing component (A) outside the scope of the claims of the present invention had insufficient optical appearance, while the compositions of the present invention (Examples 1 to 3) showed good performance.

[0100] These and other modifications and variations of the present invention can be made by those skilled in the art without departing from the spirit and scope of the present invention. Further, it should be understood that aspects of the various embodiments are interchangeable in whole or in part. Furthermore, those skilled in the art will understand that the foregoing description is merely illustrative and is not intended to limit the invention as further described in the appended claims.

Claims

1. (a) (i)At least one polycarboxylic acid selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid, (ii)Neopentyl glycol, and (iii)At least one polyol having a weight average molecular weight of 50 to 300 g / mol other than neopentyl glycol At least one polyester polyol obtained by reacting a reaction mixture containing the same, and (b)At least one polyether polyol having a weight average molecular weight of 200 to 4000 g / mol A polyol mixture containing the same is reacted with a stoichiometric excess of at least one polyisocyanate to obtain (A)At least one isocyanate group-containing component containing at least one isocyanate-terminated polyurethane prepolymer, and (B)At least one hydroxyl group-containing component Containing, The isocyanate-containing component (A) has an NCO content of more than 10% by weight and less than 14% by weight, a solvent-free polyurethane adhesive composition.

2. The polyester polyol (a) is modified with a vegetable oil selected from castor oil, soybean oil, palm oil, coconut oil, and combinations thereof. The solvent-free polyurethane adhesive composition according to claim 1.

3. The aliphatic dicarboxylic acid is selected from malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, dimer acid, their corresponding polycarboxylic anhydrides, and combinations thereof, preferably selected from adipic acid, sebacic acid, succinic acid, their corresponding polycarboxylic anhydrides, and combinations thereof C ２ -C ３６ The solventless polyurethane adhesive composition according to claim 1 or 2, which is an aliphatic dicarboxylic acid.

4. The aromatic dicarboxylic acid is selected from isophthalic acid, terephthalic acid, diphenic acid, 2,6-naphthalenedicarboxylic acid, their corresponding polycarboxylic acid anhydrides, and combinations thereof, preferably selected from isophthalic acid, terephthalic acid, their corresponding polycarboxylic acid anhydrides, and combinations thereof, C ８ - ２０ The solventless polyurethane adhesive composition according to claim 1 or 2, which is an aromatic dicarboxylic acid.

5. At least one polyol having a weight average molecular weight of 50 to 300 g / mol other than the component (iii) neopentyl glycol is ethylene glycol, diethylene glycol, 1,2-butanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, glycerol, trimethylolpropane, 1,2-propylene glycol, dipropylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, 2-butyl-2-ethylpropanediol, pentaerythritol, polytetramethylene ether glycol and combinations thereof, preferably ethylene glycol, diethylene glycol, 1,2-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol and combinations thereof. The solvent-free polyurethane adhesive composition according to claim 1 or 2.

6. At least one polyether polyol having a weight average molecular weight of 200 to 4000 g / mol of the component (b) is selected from polytetramethylene ether glycol, poly(oxypropylene) glycol, polyethylene oxide, polybutylene oxide, and ethylene oxide end-capped types of any of the foregoing, and combinations thereof, preferably selected from polytetramethylene ether glycol, poly(oxypropylene) glycol, ethylene oxide end-capped poly(oxypropylene) glycol, and combinations thereof, the solventless polyurethane adhesive composition according to claim 1 or 2.

7. The solventless polyurethane adhesive composition according to claim 6, wherein the component (b) has a weight average molecular weight (Mw) of 450 to 2,000 g / mol.

8. The polyisocyanate is selected from 4,4'-diphenylmethane diisocyanate (MDI), hydrogenated MDI (H12MDI), partially hydrogenated MDI (H6MDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), 4,4-diphenyldimethylmethane diisocyanate, dialkylene diphenylmethane diisocyanate, tetraalkylene diphenylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, isomers of toluylene diisocyanate (TDI), 1-methyl-2,4-diisocyanatocyclohexane, 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane, 1-isocyanatomethyl-3-isocyanato-1,5,5-trimethylcyclohexane (IPDI), tetramethoxybutane-1,4-diisocyanate, naphthalene-1,5-diisocyanate (NDI), butane-1,4-diisocyanate, hexane-1,6-diisocyanate (HDI), dicyclohexylmethane diisocyanate, 2,2,4-trimethylhexane-2,3,3-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, ethylene diisocyanate, methylene triphenyltriisocyanate (MIT), bisisocyanatoethyl phthalate, trimethylhexamethylene diisocyanate, 1,4-diisocyanatobutane, 1,12-diisocyanatododecane, dimer fatty acid diisocyanate, lysine ester diisocyanate, 4,4-dicyclohexylmethane diisocyanate, 1,3-cyclohexane diisocyanate or 1,4-cyclohexane diisocyanate, and combinations thereof, preferably MDI, The solventless polyurethane adhesive composition according to any one of claims 1 to 7.

9. The component (B) has a hydroxyl value in the range of 10 to 1500 mgKOH / g, preferably 56 to 560 mgKOH / g, The solventless polyurethane adhesive composition according to any one of claims 1 to 8.

10. The solvent-free polyurethane adhesive composition according to any one of claims 1 to 9, wherein the component (B) is selected from polyester polyols, polyether polyols, polyester ether polyols, polycarbonate polyols, and combinations thereof.

11. The solvent-free polyurethane adhesive composition according to any one of claims 1 to 10, wherein the component (B) has an average hydroxyl group functionality of 2 to 5, preferably 2 to 4.

12. The solvent-free polyurethane adhesive composition according to any one of claims 1 to 11, wherein the mixing ratio of the component (A) and the component (B) is 5:100 to 19:1 parts by weight, preferably 50:100 to 200:100 parts by weight.

13. A laminate comprising a first layer, a second layer, and an adhesive layer sandwiched therebetween, wherein the first layer and the second layer are each independently selected from films made of PET (polyethylene glycol terephthalate), PP (polypropylene), OPP (oriented polypropylene), CPP (cast polypropylene), BOPP (biaxially oriented polypropylene), PE (polyethylene), aluminum foil, PA (polyamide), VMPET (vacuum-deposited polyethylene glycol terephthalate), and VMCPP (vacuum-deposited cast polypropylene), preferably PET (polyethylene glycol terephthalate) and aluminum foil, and the adhesive layer is formed by curing the adhesive composition according to any one of claims 1 to 12.

14. A food pouch formed by the laminate according to claim 13.

15. Use of the solvent-free polyurethane adhesive composition according to any one of claims 1 to 12 or the laminate according to claim 13 in the manufacture of food packaging.

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