Polyol compounds and adhesive compositions prepared therewith

Abstract

A novel polyol compound represented by formula (I) is provided. A polyurethane-based adhesive composition including the polyol compound can produce an adhesive layer exhibiting excellent bonding strength and heat seal strength that will not be significantly deteriorated by a change in the weight ratio between an isocyanate component and a polyol component. Also provided are a method for preparing the polyol compound and a method for preparing the adhesive composition, and a laminate prepared using the adhesive composition.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a novel polyol compound and a method of preparing the same, an adhesive composition comprising the polyol compound and a method of preparing the same, a laminate product including an adhesive layer derived from the adhesive composition and a method of preparing the same. The adhesive layer prepared using the adhesive composition exhibits high resistance to composition variation and can achieve good bonding strength and heat seal strength that are not significantly deteriorated by a change in the weight ratio between an isocyanate component and a polyol component. BACKGROUND

[0002] Adhesive compositions are useful in a wide variety of applications. For example, they can be used to bond substrates such as polyethylene, polypropylene, polyester, polyamide, metal, paper or glassine to form composite films, i.e., laminates. The use of adhesives in different laminating end-use applications is generally known. For example, adhesives can be used to manufacture film / film and film / foil laminates for commercial use in the packaging industry.

[0003] Laminating adhesives are widely used in the manufacture of laminates. In many such known systems, the use of polyurethane-based laminating adhesives is preferred because they have many desirable properties, including good adhesion, peel strength, heat seal strength, and resistance to aggressive filled goods. However, two-component polyurethane-based adhesives always face complaints from consumers about ink compatibility issues, because there are residual active hydrogens in the ink, which can consume NCO groups in component A. This will cause a deviation between the actual mixing ratio and the design mixing ratio, and will make the adhesive not cure or sticky. In addition, the actual mixing ratio can be incorrect due to operational errors or common mistakes, which will also result in poor performance. In order to solve this problem, it is desirable to develop a robust adhesive that can maintain good performance under a wide mixing ratio tolerance.

[0004] After continuous exploration, we have surprisingly developed a novel polyol compound that can be used in a polyurethane adhesive composition to achieve one or more of the above-mentioned objectives. SUMMARY

[0005] The present disclosure provides a unique polyol compound and a polyurethane adhesive composition comprising the polyol compound.

[0006] In a first aspect of the present disclosure, the present disclosure provides a polyol compound having a structure represented by Formula I:

[0007]

[0008] wherein R1is a linear C2-C 10alkylene, which is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof; R2is a straight chain C2-C8alkylene, which is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof, preferably R2is unsubstituted straight chain C2-C8alkylene; R3and R4are the same as or different from each other and independently represent C2to C8alkyl substituted with at least two primary hydroxyl groups; and n is an integer from 5 to 500, such as 6, 7, 8, 9, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 120, 130, 140, 150, 160, 180, 190, 200, 210, 220, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, or within a numerical range obtained by combining any two of the aforementioned terminal values. According to one preferred embodiment of the present disclosure, R1is unsubstituted straight chain C3-C6alkylene. According to another preferred embodiment of the present disclosure, R2is one or a combination of ethylene, propylene, or butylene.

[0009] According to one more preferred embodiment of the present disclosure, R3and R4are the same as or different from each other and independently represented by Formula II:

[0010]

[0011] wherein each of R5, R6, and R7is independently selected from the group consisting of hydrogen, hydroxyl, C1-C4alkyl, C1-C4alkoxy, and (hydroxyl)C1-C4alkylene, with the proviso that each of R3and R4includes at least two primary hydroxyl groups; and the asterisk indicates the position at which the moiety represented by Formula II is attached to the remainder of the polyol compound represented by Formula I.

[0012] According to one preferred embodiment of the present disclosure, R3and R4are the same as or different from each other and independently selected from the group consisting of 2,2-di(hydroxymethyl)ethyl, 2,2-di(hydroxymethyl)propyl, 2,2-di(hydroxymethyl)butyl, and 2,2,2-tri(hydroxymethyl)ethyl. According to one preferred embodiment of the present disclosure, all of the hydroxyl groups in R3and R4are primary hydroxyl groups, and neither R3nor R4includes a secondary or tertiary hydroxyl group.

[0013] In a second aspect of this disclosure, a method for preparing the polyol compound of this disclosure is provided, comprising: i) reacting a dicarboxylic acid compound represented by HOC(O)-R1-COOH or its anhydride with a compound represented by HO-[R2-O] n -H represents the reaction of a poly(epoxide) to form an intermediate compound capped at both ends with carboxylic acid groups; and ii) reacting the intermediate compound with a C2 to C8 alkane having at least two primary hydroxyl groups substituted with hydroxyl groups to form the polyol compound; wherein R1 is a straight-chain C2-C 10 The alkylene group is unsubstituted or substituted with at least one side group selected from the group consisting of C1-C5 alkyl, C1-C5 alkoxy, hydroxyl, halogen, and combinations thereof; R2 is a straight-chain C2-C8 alkylene group, unsubstituted or substituted with at least one side group selected from the group consisting of C1-C5 alkyl, C1-C5 alkoxy, hydroxyl, halogen, and combinations thereof; and n is an integer from 5 to 500. Preferably, the hydroxyl-substituted C2 to C8 alkane is selected from the group consisting of: trimethylolpropane, trimethylolpropane, pentaerythritol, and combinations thereof.

[0014] In a third aspect of this disclosure, an adhesive composition is provided comprising: (A) an isocyanate component comprising a prepolymer having at least two free isocyanate groups; and (B) a polyol component comprising a polyol compound of the present disclosure. According to a preferred embodiment, the prepolymer having at least two free isocyanate groups can be prepared by reacting an isocyanate compound, such as a monomeric isocyanate compound having at least two isocyanate groups, with a polyol, such as a polyol compound of the present disclosure.

[0015] Preferably, the adhesive composition comprises any one or any combination of the following characteristics: the adhesive composition is solvent-free or may contain a solvent; the polyol compound has a hydroxyl functionality of at least 3 or at least 4; the polyol compound has a hydroxyl functionality of 4.0 to 8.0, such as 4.0, or 5.0, or 6.0, or 7.0, or 8.0; the polyol component further comprises a second polyol selected from the group consisting of: polycarbonate polyols, polyether polyols, polyester polyols, and combinations thereof, other than the polyol compound; The second polyol has a hydroxyl functionality of at least 1.2, or at least 1.5, or at least 1.6, or at least 1.8, or at least 2.0, or at least 2.2, or at least 2.5, or at least 2.8, or at least 3.0; the polyol component does not contain polyols with a hydroxyl functionality of less than 1.2, or less than 1.5, or less than 2.0 or less than 3.0; the content of the polyol compound is 40% to 80% by weight based on the total weight of the (B) polyol component, and the content of the second polyol is 20% to 60% by weight; (A) The average isocyanate functionality of the isocyanate component is greater than 1.1, such as at least 1.5, or at least 1.8, and can be up to 6.0, or up to 5.5, or up to 5.0, or up to 4.5, or up to 4.0, or up to 3.5, or up to 3.0, or up to 2.5, or up to 2.0, or up to 1.8, or up to 1.5; (A) The average isocyanate functionality of the prepolymer of the isocyanate component is greater than 1.1, such as at least 1.5, or at least 1.8, and can be up to 6.0, or up to 5.5, or up to 5.0, or up to 4.5, or up to 4.0, or up to 3.5, or up to 3.0, or up to 2.5, or up to 2.0, or up to 1.8, or up to 1.5; The number average molecular weight of the polyol compound is up to 6.0, or up to 5.0, or up to 4.0, or up to 3.0, or up to 2.0; all hydroxyl groups contained in the polyol compound of the present disclosure are primary hydroxyl groups; all hydroxyl groups contained in the polyol component are primary hydroxyl groups; the number average molecular weight Mn of the polyol compound is at least 300, such as 400 to 3,000, or 400 to 2,000, or 400 to 1,000; and the weight ratio between the isocyanate component (A) and the polyol component (B) is 100:30 to 100:100.

[0016] In a fourth aspect, this disclosure provides a method for preparing the adhesive composition of this disclosure, comprising the following steps:

[0017] (I) Provide isocyanate components, and

[0018] (II) Providing polyol compounds by: i) reacting a dicarboxylic acid compound represented by HOC(O)-R1-COOH or its anhydride with HO-[R2-O] n -H indicates poly(epoxide)

[0019] to form an intermediate compound terminated at both ends with carboxylic acid groups; ii) reacting the intermediate compound with a hydroxyl-substituted C2to C8alkane having at least two primary hydroxyl groups to form the polyol compound; wherein R1is a linear C2-C 10 alkylene, which is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof; R2is a linear C2-C8alkylene, which is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof; and n is an integer from 5 to 500; and iii) optionally, blending the polyol compound with a second polyol selected from the group consisting of a polycarbonate polyol other than the polyol compound, a polyether polyol, a polyester polyol, and combinations thereof, wherein the isocyanate component and the polyol component are stored and transported in separate packages.

[0020] According to various embodiments of the present disclosure, the adhesive composition is a two-component adhesive, wherein the isocyanate component and the polyol component are stored and transported in separate packages and are compounded immediately prior to application to any object.

[0021] In a fifth aspect of the present disclosure, the present disclosure provides a method for preparing a laminated article using the adhesive composition of the present disclosure, comprising the steps of: providing a first substrate and a second substrate, mixing the isocyanate component with the polyol component to form a curable mixture; adhering the first substrate to the second substrate by using a layer of the curable mixture; and curing the curable mixture, or allowing it to cure.

[0022] In a sixth aspect of the present disclosure, the present disclosure provides a laminated article comprising at least two substrates and an adhesive layer sandwiched therebetween, wherein the adhesive layer is formed by the reaction between (A) an isocyanate component and (B) a polyol component of the adhesive composition.

[0023] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application, as claimed. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A mechanism showing the two-step reaction for preparing the polyol compound according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0025] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Also, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference.

[0026] As disclosed herein, “and / or” means “and, or alternatively”. All ranges include the end values, unless otherwise indicated.

[0027] As disclosed herein, the term “polyol compound” or “polyol compound according to the present disclosure” specifically refers to a novel polyol compound developed by the present disclosure, unless otherwise indicated.

[0028] According to various embodiments of the present disclosure, the adhesive composition is a “two-part” or “two-package” composition comprising an isocyanate component (A) and a polyol component (B) comprising a polyol compound of the present disclosure, which is prepared by a two-step reaction: (i) reacting a dicarboxylic acid with a first polyol to obtain an intermediate compound terminated with a carboxyl group, and (ii) reacting the intermediate compound with a hydroxyl-substituted C2 to C8 alkane having at least two primary hydroxyl groups. The specifically defined polyol compound can suitably impart desired properties to the adhesive composition and to the adhesive layer prepared therefrom. According to one preferred embodiment, the isocyanate component (A) and the polyol component (B) are shipped and stored separately, compounded shortly before application during the manufacture of the laminated article or compounded immediately before application.

[0029] Isocyanate component (A)

[0030] According to one embodiment of the present disclosure, the average NCO functionality of the isocyanate component (A) is at least about 1.5, preferably from about 2 to 10, more preferably from about 2 to about 8, more preferably from about 2 to about 6, and most preferably about 2. Preferably, the isocyanate component (A) has an average NCO functionality of 2.0.

[0031] According to one preferred embodiment, the prepolymer comprised in the isocyanate component is formed by the reaction of (i) one or more isocyanate compounds comprising at least two isocyanate groups, preferably two isocyanate groups, with (ii) one or more isocyanate-reactive compounds having at least two isocyanate-reactive groups; wherein the prepolymer comprises at least two free isocyanate groups, preferably two free isocyanate groups. According to one preferred embodiment, the isocyanate compounds used for preparing the above-mentioned prepolymer are selected from the group consisting of C4-C 12 aliphatic isocyanates, C6-C 15 cycloaliphatic or aromatic isocyanates, C7-C 15aromatic-aliphatic isocyanates and combinations thereof; and more preferably selected from the group consisting of m-phenylene diisocyanate, 2,4-toluene diisocyanate and / or 2,6-toluene diisocyanate (TDI), various isomers of diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI products, hexamethylene-1,6-diisocyanate, tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate, hexahydrotoluene diisocyanate, hydrogenated MDI, naphthalene-1,5-diisocyanate, isophorone diisocyanate (IPDI), isomers of naphthalene-diisocyanate ("NDI") such as 1,5-NDI, isomers of hexamethylene diisocyanate ("HDI"), isomers of isophorone diisocyanate ("IPDI"), isomers of xylene diisocyanate ("XDI"), or mixtures thereof. According to another preferred embodiment of the present disclosure, the isocyanate-reactive compound used to make the above-mentioned prepolymer is selected from the group consisting of monomeric polyfunctional alcohols, such as C2-C 16 aliphatic polyols, C6-C 15 cycloaliphatic or aromatic polyols, C7-C 15 aromatic-aliphatic polyols; and polymeric polyols, such as polyester polyols, polyether polyols, polycarbonate polyols, blends of the polyester and polyether polyols, and combinations thereof. According to one preferred embodiment of the present application, the isocyanate-reactive compound used to make the above-mentioned prepolymer is one of the above-mentioned monomeric polyols having a hydroxyl functionality of 2.0. According to another preferred embodiment of the present application, the isocyanate-reactive compound used to make the above-mentioned prepolymer is one of the above-mentioned monomeric polyols having a hydroxyl functionality of 2.0, and more preferably is a polyester polyol having a hydroxyl functionality of 2.0. According to one embodiment of the present disclosure, the polyester polyol can have a number average molecular weight of about 200 g / mol to 5,000 g / mol, such as 300 g / mol to 3,000 g / mol, or 400 g / mol to 2,000 g / mol. According to one preferred embodiment of the present disclosure, the polyester polyol has two terminal hydroxyl groups attached to the ends of the main chain, and does not include pendant hydroxyl groups, more preferably does not include any pendant groups. According to another embodiment of the present disclosure, the isocyanate-reactive compound having at least two isocyanate-reactive groups can be a polyol compound of the present disclosure.

[0032] In one embodiment of the present disclosure, the isocyanate component (A) comprises only a prepolymer and does not include any other isocyanate compound.

[0033] In some embodiments of the present disclosure, the isocyanate component (A) further comprises one or more monomeric isocyanate compounds used in combination with the aforementioned prepolymer, and suitable monomeric isocyanate compounds can include aromatic, aliphatic, cycloaliphatic, and araliphatic monomeric isocyanates having two or more isocyanate groups, such isocyanate compounds selected from the group consisting of C4-C 12 aliphatic isocyanates, C6-C 15 cycloaliphatic or aromatic isocyanates, C7-C 15 araliphatic isocyanates, and combinations thereof; and preferably including m-phenylene diisocyanate, 2,4-toluene diisocyanate and / or 2,6-toluene diisocyanate (TDI), various isomers of diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI products, hexamethylene-1,6-diisocyanate, tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate, hexahydrotoluene diisocyanate, hydrogenated MDI, naphthylene-1,5-diisocyanate, isophorone diisocyanate (IPDI), isomers of naphthalene-diisocyanate (“NDI”) such as 1,5-NDI, isomers of hexamethylene diisocyanate (“HDI”), isomers of isophorone diisocyanate (“IPDI”), isomers of xylene diisocyanate (“XDI”), or mixtures thereof.

[0034] Compounds having isocyanate groups, such as the aforementioned prepolymer and optional monomeric isocyanate compounds, can be characterized by the parameter “%NCO”, which is the amount of isocyanate groups by weight based on the weight of the compound. The parameter %NCO can be measured by the method of ASTM D 2572-97(2010). According to one embodiment of the present disclosure, the prepolymer and monomeric isocyanate compounds can have a %NCO of at least 3 wt.%, or at least 5 wt.%, or at least 7 wt.%. In some embodiments, the isocyanate compounds have a %NCO of no more than 40 wt.%, 35 wt.%, 30 wt.%, or 25 wt.%, or 22 wt.%, or 20 wt.%.

[0035] According to one embodiment of the present disclosure, the content of isocyanate compounds used to prepare the prepolymer is from 30 wt% to 65 wt%, with the total weight of the isocyanate component (A) taken as 100 wt%. According to one preferred embodiment of the present disclosure, the content of isocyanate compounds used to prepare the prepolymer can be in the numerical range obtained by combining any two of the following endpoint values: 27 wt%, 30 wt%, 33 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, and 70 wt%. According to another preferred embodiment of the present disclosure, the content of isocyanate reactive compounds used to prepare the prepolymer can be in the numerical range obtained by combining any two of the following endpoint values: 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 28 wt%, 30 wt%, 32 wt%, 35 wt%, 37 wt%, 40 wt%, 42 wt%, 45 wt%, 48 wt%, 50 wt%, 52 wt%, 54 wt%, 55 wt%, 57 wt%, 60 wt%, 62 wt%, 65 wt%, 67 wt%, 70 wt%, 72 wt%, 75 wt%, 80 wt%, 82 wt%, and 85 wt%, with the total weight of the isocyanate component (A) taken as 100 wt%.

[0036] Polyol component (B)

[0037] According to various embodiments of the present disclosure, the polyol component comprises a unique polyol compound of the present application, which is prepared by (i) reacting a dicarboxylic acid with a first polyol to obtain an intermediate compound terminated with a carboxyl group, and (ii) reacting the intermediate compound with a compound having a plurality of primary hydroxyl groups.

[0038] According to various embodiments of the present disclosure, the dicarboxylic acid can be represented by the general formula HOC(O)-R1-COOH, wherein R1 is an alkylene group comprising from 1 to 10 carbon atoms, preferably the number of carbons of R1 is an integer of 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. According to one preferred embodiment of the present disclosure, the dicarboxylic acid is selected from the group consisting of adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, phthalic anhydride, and any combination thereof.

[0039] According to various embodiments of the present disclosure, the first polyol can be a polyether polyol derived from ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, triol, tetraol, or combinations thereof. The first polyol can also include optional co-units derived from polycarbonate polyols, polyester polyols, and combinations thereof. According to one preferred embodiment of the present disclosure, the first polyol is a polyether polyol, such as polyethylene glycol or polypropylene glycol. According to another preferred embodiment of the present disclosure, the first polyol is a polyethylene glycol or polypropylene glycol having a number average molecular weight Mn of at least 200 g / mol, or at least 300 g / mol, or at least 400 g / mol. According to another preferred embodiment of the present disclosure, the first polyol is a polyethylene glycol or polypropylene glycol having a hydroxyl functionality of 2.0 and including only two hydroxyl end groups attached to the ends of the main chain (i.e., not including pendant hydroxyl groups).

[0040] The reaction mechanism between the dicarboxylic acid and the first polyol is shown in Figure 1 where the ratio of dicarboxylic acid to first polyol is controlled such that the resulting intermediate compound is terminated with carboxyl groups on both ends of the main chain. According to one preferred embodiment of the present disclosure, the first polyol is a polyether polyol including two terminal hydroxyl groups, and the molar ratio between the dicarboxylic acid and the first polyol is 2: 1. According to the reaction mechanism as shown in Figure 1In the preferred embodiment shown, the first polyol is PEG-400, i.e., polyethylene glycol having a number average molecular weight of about 400 g / mol. According to various embodiments of the present disclosure, the first polyol is a poly(alkylene oxide) (e.g., polyethylene oxide, polypropylene oxide, polybutylene oxide, and blends or copolymers thereof) having a degree of polymerization of 5 to 500, such as 6 to 400, or 8 to 300, or 10 to 200, or 12 to 100, or within a numerical range obtained by combining any two of the aforementioned endpoints. According to alternative embodiments of the present disclosure, the first polyol can be a polyether polyol having a number average molecular weight Mn within a numerical range obtained by combining any two of the following endpoints: 200 g / mol, 300 g / mol, 400 g / mol, 500 g / mol, 600 g / mol, 700 g / mol, 800 g / mol, 900 g / mol, 1,000 g / mol, 1,200 g / mol, 1,500 g / mol, 1,800 g / mol, 2,000 g / mol, 2,200 g / mol, 2,500 g / mol, 2,800 g / mol, 3,000 g / mol, 3,200 g / mol, 3,500 g / mol, 3,800 g / mol, 4,000 g / mol, 4,200 g / mol, 4,500 g / mol, 4,800 g / mol, and 5,000 g / mol.

[0041] The intermediate compound is then reacted with a compound comprising at least two primary hydroxyl groups (e.g., trimethylolmethane, trimethyloloethane, trimethylolpropane, or pentaerythritol), preferably in a molar ratio of at least 1 :2, more preferably in a molar ratio of 1 :2, to form the polyol compound of the present disclosure. According to one preferred embodiment of the present disclosure, the polyol compound of the present disclosure is a hydroxyl-terminated, high-functionality polyester polyol having a hydroxyl functionality of at least 3, or at least 3.5, or at least 4.0, or at least 4.5, or at least 5.0, or at least 5.5, or at least 6.0, and more preferably 4.0. Preferably, all of the hydroxyl groups contained in the high-functionality polyol compound are primary hydroxyl groups, i.e., the high-functionality polyol compound of the present disclosure does not include secondary and tertiary hydroxyl groups.

[0042] According to one preferred embodiment of the present disclosure, the polyol component does not comprise any polyol other than the polyol compound of the present disclosure. According to one more preferred embodiment of the present disclosure, the polyol component further comprises a second polyol selected from the group consisting of polycarbonate polyols, polyether polyols, polyester polyols, and combinations thereof other than the polyol compound. According to one more preferred embodiment of the present disclosure, the second polyol has a number average molecular weight Mn in the numerical range obtained by combining any two of the following endpoints: 200 g / mol, 300 g / mol, 400 g / mol, 500 g / mol, 600 g / mol, 700 g / mol, 800 g / mol, 900 g / mol, 1,000 g / mol, 1,200 g / mol, 1,500 g / mol, 1,800 g / mol, 2,000 g / mol, 2,200 g / mol, 2,500 g / mol, 2,800 g / mol, 3,000 g / mol, 3,200 g / mol, 3,500 g / mol, 3,800 g / mol, 4,000 g / mol, 4,200 g / mol, 4,500 g / mol, 4,800 g / mol, and 5,000 g / mol. According to one more preferred embodiment of the present disclosure, the second polyol is a hydroxyl-terminated polyol having a hydroxyl functionality of at least 1.2, at least 1.5, at least 1.6, at least 1.8, at least 2.0, at least 2.2, at least 2.5, at least 2.8, at least 3, or at least 3.5, or at least 4.0, or at least 4.5, or at least 5.0, or at least 5.5, or at least 6.0, and more preferably 1.5 to 3.0. Preferably, all hydroxyl groups contained in the second polyol are primary hydroxyl groups, i.e. the second polyol does not include secondary and tertiary hydroxyl groups. According to one embodiment of the present disclosure, the content of the polyol compound is 40 to 80% by weight, and the content of the second polyol is 20 to 60% by weight, based on the total weight of the (B) polyol component.

[0043] According to one preferred embodiment of the present application, the polyol compound can be synthesized by an esterification reaction in the presence or absence of an esterification catalyst such as a base catalyst or an acid catalyst at a temperature of 100°C to 300°C, such as 130°C to 250°C, or 150°C to 230°C, or 160°C to 210°C, at atmospheric pressure or under a reduced pressure of 0.001 bar to 1 bar, such as 0.01 bar to 0.9 bar, or 0.1 bar to 0.9 bar, or 0.2 bar to 0.9 bar, or 0.3 bar to 0.9 bar, or 0.5 bar to 0.9 bar, or 0.8 bar to 0.9 bar, for a duration of 10 minutes to 10 hours, or 0.5 hour to 8 hours, or 1 hour to 5 hours, or 1.5 hours to 4 hours, or 2 hours to 3 hours.

[0044] Application of the adhesive composition

[0045] According to various embodiments of the present disclosure, the two-component adhesive composition of the present disclosure can include one or more solvents or can be completely solvent free. As disclosed herein, the terms “solvent free”, “solventless” or “non-solvent” can be used interchangeably and shall be interpreted to mean that the mixture of all raw materials used to make the adhesive composition contains less than 3 wt.%, preferably less than 2 wt.%, preferably less than 1 wt.%, more preferably less than 0.5 wt.%, more preferably less than 0.2 wt.%, more preferably less than 0.1 wt.%, more preferably less than 100 ppm by weight, more preferably less than 50 ppm by weight, more preferably less than 10 ppm by weight, more preferably less than 1 ppm by weight of any organic or inorganic solvent based on the total weight of the mixture of raw materials. As disclosed herein, the term “solvent” refers to organic and inorganic liquids whose function is to dissolve only one or more solid, liquid or gaseous materials without initiating any chemical reaction. In other words, although some organic compounds such as ethylene glycol and propylene glycol and water, which are commonly considered as “solvents” in polymerization technology, are used to make the two-component polyurethane-based adhesive composition, none of them belong to “solvents” as they primarily function as isocyanate-reactive functional species or chain extenders, etc. by initiating chemical reactions.

[0046] According to various embodiments of the present disclosure, the weight ratio between the isocyanate component (A) and the polyol component (B) is 100:30 to 100:100. According to one preferred embodiment, the weight ratio can be in the numerical range obtained by combining any two of the following ratios: 100:30, 100:40, 100:50, 100:60, 100:70, 100:80, 100:90, and 100:100. According to one preferred embodiment of the present application, the weight ratio between the isocyanate component (A) and the polyol component (B) is adjusted so that the weight ratio between the prepolymer in the isocyanate component (A) and the polyol compound in the polyol component (B) is 100:10 to 100:100, or 100:20 to 100:90, or 100:30 to 100:80, or can be in the numerical range obtained by combining any two of the following ratios: 100:30, 100:40, 100:45; 100:50, 100:55, 100:60, 100:65, 100:70, 100:75, and 100:80. One of the technical advantages of the present disclosure is that the bonding strength and heat seal strength of the (cured) adhesive prepared by using the adhesive composition of the present disclosure will not be significantly deteriorated by the change in the above ratio. For example, when the weight ratio between the isocyanate compound (particularly, the prepolymer including at least two isocyanate groups) in the isocyanate component (A) and the polyol compound in the polyol component (B) is changed between 100:50 to 100:80, or between 100:50 to 100:40 or 100:45, the magnitude of the change in the bonding strength and heat seal strength of the (cured) adhesive prepared by using the adhesive composition (with and without BIB (Boiling-in-Bag) test) is less than ±20%, or less than ±15%, or less than ±10%, or less than ±8%, or less than ±6%, or less than ±5%, or less than ±3%, or less than ±2%, or less than ±1%, or less than ±0.5%, wherein the bonding strength and heat seal strength of the (cured) adhesive prepared by using the adhesive composition with a ratio of 100:50 is considered as 100%.

[0047] As described above, the isocyanate component (A) and the polyol component (B) are shipped and stored separately, and are compounded shortly before application or just before application during the manufacture of the laminate. In some embodiments, the isocyanate component and the polyol component are liquid at ambient temperature. When it is desired to use the adhesive composition, the isocyanate component and the polyol component are brought into contact with each other and mixed together. Once mixed, a polymerization (curing) reaction occurs between the free isocyanate groups in the isocyanate component (A) and the hydroxyl groups in the polyol component (B) to form a polyurethane that exhibits adhesive functionality in the adhesive layer between the two or more substrates. The adhesive composition formed by bringing the two components into contact can be referred to as a “curable mixture”.

[0048] One or more catalysts can optionally be used to promote or accelerate the polymerization reaction described above for preparing the prepolymer in the isocyanate component (A) and / or the polymerization between the prepolymer of (A) and the polyol component (B).

[0049] The catalyst can include any substance that can promote the reaction between isocyanate groups and hydroxyl groups. Without being limited by theory, the catalyst can include, for example, glycine salts; tertiary amines; tertiary phosphines such as trialkyl phosphines and dialkyl benzyl phosphines; morpholine derivatives; piperazine derivatives; chelates of various metals such as those obtainable from acetylacetone, benzoylacetone, trifluoroacetylacetone, ethyl acetoacetate, and the like with metals such as Be, Mg, Zn, Cd, Pd, Ti, Zr, Sn, As, Bi, Cr, Mo, Mn, Fe, Co, and Ni; acidic metal salts of strong acids such as ferric chloride and tin chloride; salts of various metals such as alkali metals, alkaline earth metals, Al, Sn, Pb, Mn, Co, Ni, and Cu with organic acids; organotin compounds such as tin(II) salts of organic carboxylic acids, for example tin(II) diacetate, tin(II) dioctoate, tin(II) diethylhexanoate, and tin(II) dilaurylate, and dialkyltin(IV) salts of organic carboxylic acids, for example dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate; bismuth salts of organic carboxylic acids, for example bismuth octoate; organometallic derivatives of trivalent and pentavalent As, Sb, and Bi, and carbonyl metals of iron and cobalt; or mixtures thereof.

[0050] Generally, the catalyst used herein is present in an amount greater than zero and up to 1.0 wt.%, preferably up to 0.5 wt.%, more preferably up to 0.05 wt.%, based on the total weight of all reactants.

[0051] The adhesive composition of the present disclosure can optionally include any additional adjuvants and / or additives for specific purposes.

[0052] In one embodiment of the disclosure, one or more of the co-agents and / or additives can be selected from the group consisting of other co-catalysts, surfactants, flexibilizers, flow modifiers, tackifiers such as aminosilane or epoxysilane or phosphate ester, diluents, stabilizers, plasticizers, catalyst deactivators, dispersants, and mixtures thereof.

[0053] A method of producing a laminate using the adhesive composition is also disclosed. In some embodiments, the adhesive composition, such as the adhesive compositions discussed above, is liquid. In some embodiments, the composition is a liquid at 25 °C. Even if the composition is a solid at 25 °C, the composition can be heated as needed to convert it to a liquid state. A layer of the composition is applied to the surface of a substrate or film. A “substrate / film” is any structure that is 0.5 mm or less in one dimension and 1 cm or more in both of the other two dimensions. A polymeric film is a film made from a polymer or mixture of polymers. The composition of a polymeric film is typically 80 wt% or more of one or more polymers. In some embodiments, the thickness of the layer of the curable mixture applied to the film is 1 pm to 5 pm.

[0054] In some embodiments, the surface of another substrate / film is contacted with the layer of the curable mixture to form an uncured laminate. The adhesive composition can be applied by a conventional laminator, for example, a Labo-Combi 400 machine from Nordmeccanica. The curable mixture is then cured or allowed to cure. The uncured laminate can be subjected to pressure, for example, by passing through nip rollers, which can or can not be heated. The uncured laminate can be heated to accelerate the curing reaction. Suitable substrates / films include paper, woven and nonwoven fabrics, metal foils, polymers, and metal-coated polymers. The film optionally has a surface on which an image is printed with ink; and the ink can be in contact with the adhesive composition. In some embodiments, the substrate / film is a polymeric film or a metal-coated polymeric film, and more preferably a polymeric film.

[0055] 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 in which a roll of a first substrate / film is unwound and transported through two or more stations in which the isocyanate component (A) and the polyol component (B) are mixed to form the adhesive composition (curable mixture) of the present application which is applied to the surface of the first substrate / film. The adhesive composition (curable mixture) of the present application can be applied more than once to achieve the desired film thickness or composition distribution. A second substrate / film can be applied to the curable adhesive layer with or without the aid of a roll. Heating or irradiation devices can be arranged to promote curing of the coated adhesive layer and a roll can also be used to enhance the adhesion strength within the laminate. The second substrate / film can be the same or different from the first substrate / film and can also be unwound from a roll. The length of the unwound substrate / film is typically from 10 meters to 20,000 meters, from 10 meters to 15,000 meters and preferably from 20 meters to 10,000 meters and is typically transported at a speed ranging from 0.1 meter / minute to 60 meters / minute, preferably from 3 meters / minute to 45 meters / minute, more preferably from 5 meters / minute to 15 meters / minute. At the end of the continuous technique, the cured laminate product is wound on a main shaft.

[0056] The laminates disclosed herein can be cut or otherwise shaped to have a shape suitable for any desired purpose, such as packaging material.

[0057] While the last general description and the following examples focus primarily on two-component PU-based adhesive compositions, the unique hydroxyl compounds of the present disclosure can be used as isocyanate-reactive compounds for any other polyurethane-based products such as coatings, paints, insulation materials, packaging materials, foam materials, etc. and impart the technical advantages described above to these products.

[0058] Examples

[0059] Some embodiments of the present application will now be described in the following examples, in which all parts and percentages are by weight unless otherwise indicated. The scope of the present disclosure is of course not limited to the formulations described in these examples, however. Rather, the examples are merely illustrative of the present disclosure.

[0060] The information of the raw materials used in the examples is listed in Table 1 below:

[0061] Table 1. Raw materials used in the examples

[0062]

[0063] Synthesis examples 1 to 4 Synthesis of the polyol compounds (poly-hydroxyl functionalized polyester polyols) of the present disclosure

[0064] Carbowax 4000 (PEG 4000) was added to a flask equipped with stirring blade and oil bath and heated to a temperature of 210 °C. The reaction was continued for 1 hour to produce the intermediate compound terminated with carboxyl groups. The reaction mixture was cooled to 160 °C and then 2 mol of trimethylolpropane, pentaerythritol or glycerol was added thereto. The flask was heated again to 210 °C until the mixture in the flask showed an acid value of less than 3.0. The reaction product was then dried at 210 °C under a vacuum of 880 mbar (26 inch of mercury) for 1 hour to achieve an acid value of 1.0 mg KOH / g. The polyester polyols prepared in Synthesis Example 4 were designated as HF 5 to HF 8, respectively. TM PEG 400 or Carbowax 400 TM PEG 1000 and 2 mol of adipic acid were added to a flask equipped with stirring blade and oil bath and heated to a temperature of 210 °C. The reaction was continued for 1 hour to produce the intermediate compound terminated with carboxyl groups. The reaction mixture was cooled to 160 °C and then 2 mol of trimethylolpropane, pentaerythritol or glycerol was added thereto. The flask was heated again to 210 °C until the mixture in the flask showed an acid value of less than 3.0. The reaction product was then dried at 210 °C under a vacuum of 880 mbar (26 inch of mercury) for 1 hour to achieve an acid value of 1.0 mg KOH / g. The polyester polyols prepared in Synthesis Example 1 to 3 were designated as HF 1 to HF 4, respectively.

[0065] The OH value (measured according to ASTM D6342:2008) and viscosity (measured according to GB-T12008.8-1992) of the resulting products were then characterized and summarized in Table 2.

[0066] Table 2. Formulation and properties of polyol component (B)

[0067] Composition Charge ratio OH value (mg KOH / g) Viscosity (cp at 25 C) Synthesis example 1 : HF1 PEG 400-AA-TMP 1:2:2 250 5800 Synthesis example 2: HF2 PEG 1000-AA-TMP 1:2:2 150 5000 Synthesis example 3: HF3 PEG 1000-AA-PTT 1:2:2 226 5900 Synthesis example 4: HF4 PEG 400-AA-Gl 1:2:2 286 6500

[0068] Examples 1-4 and comparative examples 1-2

[0069] HF 1 to HF 4 were mixed with VORANOL CP450 to form polyol components (B) as shown in Table 3 below, and these polyol components (B) were used in Inventive Examples 1 to 4. Comparative polyol components (B) were also prepared by mixing polyether polyol (VORANOL CP450) with polyester polyol (Bester 90) and used in two comparative examples. TM TM CP450) with polyester polyol (Bester 90) and used in two comparative examples. TM

[0070] Table 3. Formulation of polyol component (B) of examples 1 to 4 and comparative examples 1 to 2

[0071] Composition and charge ratio OH value (mg KOH / g) B1 CP 450 / HF1 = 35 / 65 294 B2 CP 450 / HF2 = 35 / 65 230 B3 CP 450 / HF3 = 35 / 65 279 B4 CP450 / Bester TM 90 = 35 / 65 240 B5 CP 450 / HF4 = 35 / 65 321

[0072] The adhesive compositions of Inventive Examples 1 to 4 and Comparative Examples 1 to 2 were synthesized according to the formulations listed in Table 4, and their bond strength (BS) and heat seal strength (HS) were characterized by using the following techniques.

[0073] Table 4: Formulation of examples 1-8 and comparative examples 1-2

[0074]

[0075] ​​

[0076] The polyol components prepared in Table 3 were combined with Dow commercial (NCO prepolymer) MorFree 1000 TM 698A were paired in the ratios shown in Table 4 to form adhesives and performance evaluations were conducted.

[0077] Laminates were prepared with these adhesives in a Nordmeccanica Labo-Combi 400 machine under the following processing conditions: line speed set at 120 and 150 mpm, transfer roller temperature at 45 °C, nip temperature set at 60 °C, and coating weight set at 1.8 gsm. Different substrates were selected to form PET / PE60 as the test laminate structure, which was characterized by the following techniques.

[0078] Test method

[0079] Bonding strength (BS)

[0080] Laminates prepared with adhesive compositions, PET substrate, and PE60 substrate were cut into 15 mm wide strips for T-peel testing at a crosshead speed of 250 mm / min using an Instron Corporation 5940 Series Single Column Table System. During testing, the tail of each strip was gently pulled with a finger to ensure the tail was held at 90 degrees to the direction of peel. Three strips were tested per sample and an average was calculated. Results are expressed in N / 15 mm. Higher values indicate better bond strength.

[0081] Heat seal strength (HS)

[0082] Laminates prepared with adhesive compositions, PET substrate, and PE60 substrate were heat sealed in a Brugger Company HSG-C heat sealer at a sealing temperature of 140 °C and a pressure of 300 N for 1 second, then cooled and cut into 15 mm wide strips for heat seal strength testing at a crosshead speed of 250 mm / min using an Instron Corporation 5940 Series Single Column Table System. Three strips were tested per sample and an average was calculated. Results are expressed in N / 15 mm. Higher values indicate better heat seal strength.

[0083] Boil in Bag (BiB) Table 5: Results of performance evaluation of PET / PE 60 laminates ​

[0084] The laminates prepared with the adhesive composition were cut into 8 cm x 12 cm pieces, which were heat sealed to form pouches with water encapsulated therein. The pouches were then immersed in boiling water for 30 minutes, during which time the pouches were kept fully immersed in the boiling water. After 30 minutes of boiling, the pouches were inspected for any defects, such as tunneling, de-lamination, or leakage, and the extent of the defects, if any, was recorded. The samples that passed the test should show no signs of tunneling, de-lamination, or leakage. The pouches were opened, emptied, and cooled, and then cut into 15 mm wide strips to test their T-Peel Adhesion Strength and Heat Seal Strength in an Instron 5943 machine. Three strips were tested for each sample and the average was calculated.

[0085] The adhesion strength, heat seal strength, and BiB properties are summarized in Table 5, from which it can be seen that all of the inventive examples exhibited excellent HS and BS that did not degrade to an unacceptable extent, regardless of the ratio between the two components, whereas the comparative examples exhibited much higher degradation of the HS and BS when the ratio between component (A) and component (B) was varied, and channels would form during the in-pouch boiling (BiB) treatment.

[0086] ​

[0087]

Claims

1. A polyol compound having a structure represented by Formula I: Formula I wherein: R1is a linear C2-C8alkylene that is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof; R2is a linear C2-C8alkylene that is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof; R3and R4are the same as or different from each other and are independently selected from the group consisting of 2,2-di(hydroxymethyl)ethyl, 2,2-di(hydroxymethyl)propyl, 2,2-di(hydroxymethyl)butyl, 2,2,2-tri(hydroxymethyl)ethyl, and combinations thereof, provided that each of R3and R4includes at least two primary hydroxyl groups; and n is an integer from 5 to 500. wherein R1is a linear C1-C 10 alkylene which is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof; 2. A method for making the polyol compound of claim 1, comprising: i) reacting a diol compound having at least two primary hydroxyl groups with a dihaloalkane to form an intermediate compound; and ii) reacting the intermediate compound with a hydroxyl-substituted C2to C8alkane having at least two primary hydroxyl groups to form the polyol compound, wherein the hydroxyl-substituted C2to C8alkane is selected from the group consisting of trimethylolmethane, trimethyloloethane, trimethylolpropane, pentaerythritol, and combinations thereof; wherein: R1is a linear C2-C8alkylene that is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof; R2is a linear C2-C8alkylene that is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof; R3and R4are the same as or different from each other and are independently selected from the group consisting of 2,2-di(hydroxymethyl)ethyl, 2,2-di(hydroxymethyl)propyl, 2,2-di(hydroxymethyl)butyl, 2,2,2-tri(hydroxymethyl)ethyl, and combinations thereof, provided that each of R3and R4includes at least two primary hydroxyl groups; and n is an integer from 5 to 500.

3. An adhesive composition comprising: (A) an isocyanate component comprising a prepolymer having at least two free isocyanate groups; and (B) a polyol component comprising the polyol compound of claim 1.

4. The adhesive composition of claim 3, wherein the polyol component further comprises at least one second polyol selected from the group consisting of polycarbonate polyols, polyether polyols, polyester polyols, and combinations thereof other than the polyol compound of claim 1.

5. The adhesive composition of claim 3, wherein the prepolymer is prepared by reacting an isocyanate compound having at least two isocyanate groups with the polyol compound of claim 1. i) reacting a dicarboxylic acid compound represented by HOC(O)-R1-COOH or an acid anhydride thereof with a poly(alkylene oxide) represented by HO-[R2-O] n -H to form an intermediate compound capped at both ends with carboxylic acid groups; 6. The adhesive composition of claim 4, wherein the content of the polyol compound of claim 1 is 40 to 80 percent by weight, and the content of the second polyol is 20 to 60 percent by weight, based on the total weight of the (B) polyol component.

7. The adhesive composition of claim 3, wherein the weight ratio between the (A) isocyanate component and the (B) polyol component is 100:30 to 100:100; and the adhesive composition comprises a solvent or is solventless. wherein R1is a linear C1-C 10 alkylene which is unsubstituted or substituted with at least one pendant group selected from the group consisting of C1-C5alkyl, C1-C5alkoxy, hydroxyl, halogen, and combinations thereof; 8. A method for making a laminate article having the adhesive composition of claim 3, comprising the steps of providing a first substrate and a second substrate; mixing the (A) isocyanate component and the (B) polyol component to form a curable mixture; adhering the first substrate to the second substrate by using a layer of the curable mixture; and curing the curable mixture. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ curing the curable mixture, or allowing it to cure.

9. A laminate comprising at least two substrates and an adhesive layer sandwiched therebetween, wherein the adhesive layer is formed by the reaction between the (A) isocyanate component and the (B) polyol component of the adhesive composition according to claim 3.

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