Polyurethane adhesive

Abstract

The polyurethane adhesive may include an isocyanate prepolymer and a polyol component. The isocyanate prepolymer is the reaction product of from 35% to 95% by weight of a polyisocyanate and from 65% to 5% by weight of a non-dimer acid-based polyester polyol. The non-dimer acid-based polyester polyol may include the reaction product of a primary polyol having a hydroxyl functionality of at least 3 and a weight average molecular weight of 800 g / mol or less, a C4 to C20 non-dimer acid dicarboxylic acid, and a C10 to C20 aliphatic monocarboxylic acid. The polyol component comprises from 20% to 80% by weight of a hydrophobic polyol, from 3% to 15% by weight of a phosphate modified polyol, and from 10% to 30% by weight of a vegetable oil polyurethane polyol.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to adhesives, and in particular, polyurethane adhesives. Background Art

[0002] In the past few years, with the continued adoption of electric vehicles (EV) around the world, the economic production of battery packs has experienced great progress. Due to low cost, low volatility, high body strength and toughness, polyurethane adhesives have become a popular solution for battery pack assembly, where battery cells are bonded together using polyurethane adhesives. The bonding substrates used for battery pack assembly mainly include aluminum alloys (Al alloys), polyethylene terephthalate (PET) films and polycarbonate films and other materials, among which bonding Al alloy-Al alloy surfaces is usually the most challenging aspect of battery pack assembly. Specifically, due to the high surface energy and the absence of organic chemical groups on the Al alloy surface, it is difficult to achieve effective bonding between Al alloys.

[0003] On the other hand, moisture resistance of polyurethane components (including polyol parts and isocyanate parts) is another important industrial need. This is because both polyol parts and isocyanate parts easily absorb moisture. For the isocyanate part, the absorbed moisture causes a reduction in the isocyanate (NCO) content and the formation of a solid skin starting on the surface of the component. Therefore, the reduced NCO content may make the feed ratio between the reaction groups incorrect, and the thick skin may block the storage tank and / or distribution channel, thereby causing product defects and production interruptions, respectively. For the polyol part, the absorbed moisture can cause bubbles to form in the adhesive after mixing and / or distribution. Therefore, the more moisture-resistant the adhesive, the better.

[0004] To provide moisture resistance, PU adhesives are often incorporated with hydrophobic compounds such as vegetable oils, OH-terminated polyolefins, dimer acid-based polyesters, and blocky hydrophobic plasticizers. However, these compounds can be costly, lead to long production cycle times (due to low reactivity) and often result in poor bond strength at Al alloy-Al alloy interfaces. Therefore, new technologies are needed to address industry challenges and enable advanced adhesive products for batteries, especially those used in EV applications. Summary of the invention

[0005] The present disclosure provides polyurethane adhesives comprising both isocyanate prepolymers and polyol components, which provide high reactivity for effective bonding of Al alloy-Al alloy interfaces at low cost. Therefore, such polyurethane adhesives as provided herein can be beneficial in helping to solve industrial challenges and achieve advanced adhesive products for batteries, especially those for EV applications.

[0006] The present disclosure provides a polyurethane adhesive comprising an isocyanate prepolymer and a polyol component, wherein the isocyanate prepolymer is the reaction product of: 35 weight percent (wt%) to 95 wt% of a polyisocyanate; and 65 wt% to 5 wt% of a non-dimer acid-based polyester polyol, wherein the wt% is based on the total weight of the isocyanate prepolymer, and the wt% of the polyisocyanate and the non-dimer acid-based polyester polyol does not exceed 100 wt% in total. For various embodiments, the non-dimer acid-based polyester polyol comprises a reaction product of a primary polyol having a hydroxyl functionality of at least 3 and a weight average molecular weight of 800 g / mol or less, a C4 to C20 non-dimer acid dicarboxylic acid, and a C10 to C20 aliphatic monocarboxylic acid, wherein the aliphatic monocarboxylic acid and the primary polyol have a molar ratio of greater than 0.9:1 to 6.5:1 (monocarboxylic acid: polyol), and the aliphatic monocarboxylic acid is present in the isocyanate prepolymer in a range of greater than 7.2 wt % to 55 wt % based on the total weight of the isocyanate prepolymer. The polyol component comprises 20 wt % to 80 wt % of a hydrophobic polyol; 3 wt % to 15 wt % of a phosphate-modified polyol; and 10 wt % to 30 wt % of a vegetable oil polyurethane polyol, wherein the wt % is based on the total weight of the polyol component, and the wt % of the hydrophobic polyol, the phosphate-modified polyol, and the vegetable oil polyurethane polyol does not exceed 100 wt % in total. DETAILED DESCRIPTION

[0007] The present disclosure provides polyurethane adhesives comprising both isocyanate prepolymers and polyol components, which provide high reactivity for effective bonding of Al alloy-Al alloy interfaces at low cost. Therefore, such polyurethane adhesives as provided herein can be beneficial in helping to solve industrial challenges and achieve advanced adhesive products for batteries, especially those for EV applications.

[0008] Numerical ranges disclosed herein include all values ​​from the lower limit to the upper limit, and include the lower limit and the upper limit. For ranges containing exact values ​​(e.g., ranges from 1 or 2 or 3 to 5 or 6 or 7), any subranges between any two exact values ​​are included (e.g., above ranges 1 to 7 include subranges 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6, etc.).

[0009] Isocyanates containing more than one, or at least two, isocyanate groups are "polyisocyanates." Isocyanates may be aromatic or aliphatic.

[0010] For various embodiments, the disclosure provides polyurethane adhesives, which are the reaction products of isocyanate prepolymers and polyol components. As provided herein, isocyanate prepolymers are the reaction products of polyisocyanates and non-dimer acid-based polyester polyols, as discussed herein. Polyol components comprise hydrophobic polyols, phosphate-modified polyols and vegetable oil polyurethane polyols, as discussed herein. Polyol components may optionally comprise polyether polyols. Each component in the various components is discussed below.

[0011] Polyol components

[0012] For various embodiments, the polyol component comprises 20 weight percent (wt%) to 80 weight percent of a hydrophobic polyol; 3 weight percent to 15 weight percent of a phosphate-modified polyol; and 10 weight percent to 30 weight percent of a vegetable oil polyurethane polyol, wherein the weight percent is based on the total weight of the polyol component, and the weight percents of the hydrophobic polyol, the phosphate-modified polyol, and the vegetable oil polyurethane polyol do not exceed 100 weight percent in total. Preferably, the polyol component comprises 24 weight percent to 40 weight percent of a hydrophobic polyol; 6 weight percent to 11 weight percent of a phosphate-modified polyol; and 11 weight percent to 20 weight percent of a vegetable oil polyurethane polyol, wherein the weight percent is based on the total weight of the polyol component, and the weight percents of the hydrophobic polyol, the phosphate-modified polyol, and the vegetable oil polyurethane polyol do not exceed 100 weight percent in total. Most preferably, the polyol component comprises 25 wt % to 30 wt % of a hydrophobic polyol; 7 wt % to 9 wt % of a phosphate-modified polyol; and 11 wt % to 15 wt % of a vegetable oil polyurethane polyol, wherein the wt % is based on the total weight of the polyol component and the weight % of the hydrophobic polyol, the phosphate-modified polyol and the vegetable oil polyurethane polyol does not exceed 100 wt % in total.

[0013] Hydrophobic polyols

[0014] The hydrophobic polyol used for the polyol component refers to a hydrophobic polyol with at least two hydroxyl groups. In one embodiment, the hydrophobic polyol is castor oil or a derivative thereof. The polyol component comprises 20 wt % to 80 wt %, preferably 22 wt % to 60 wt %, more preferably 24 wt % to 40 wt %, even more preferably 25 wt % to 30 wt % of the hydrophobic polyol, preferably castor oil, based on the gross weight of the polyol component.

[0015] Phosphate modified polyols

[0016] The phosphate-modified polyol used in the polyol component is preferably a phosphate-modified polyol, more preferably a phosphate ester polyol. The phosphate ester polyol can be prepared from trifunctional propylene glycol, polyphosphoric acid and polyisocyanate. Commercially available examples of trifunctional propylene glycol include those sold under the trade name VORANOL TM CP-450, VORANOL TM CP-260, VORANOL TM CP-755 and VORANOL TM CP-1055 is a product sold, each of which can be obtained from The Dow Chemical Company. In some embodiments, the phosphate polyol has a phosphoric acid content of less than 4% by weight based on the weight of the phosphate polyol, or a phosphoric acid content of 0% to 3% by weight based on the weight of the phosphate polyol, or a phosphoric acid content of 1.5% to 2.5% by weight based on the weight of the phosphate polyol. In some embodiments, the phosphate polyol has a viscosity of less than 40,000 cps at 25°C or less than 30,000 cps at 25°C, as measured by the method of ASTM D2196. In some embodiments, the phosphate polyol has a hydroxyl equivalent of less than 330 g / mol. In some embodiments, the phosphate polyol has a trifunctional polyether polyol with an equivalent weight of less than 2,000 g / mol based on 0% to 100% by weight of the weight of the phosphate polyol. The polyol component comprises 3 to 15 wt %, preferably 4 to 13 wt %, more preferably 5 to 12 wt %, even more preferably 6 to 11 wt %, most preferably 7 to 9 wt % of a phosphate-modified polyol, preferably a phosphate ester polyol, based on the total weight of the polyol component.

[0017] Vegetable oil polyurethane polyol

[0018] The vegetable oil polyurethane polyol for polyol component is the reaction product of the reaction mixture of vegetable oil, polyisocyanate and polyol containing the hydrophobic polyol with at least two hydroxyl groups.Polyisocyanate can be chemically bonded to polyol to form prepolymer.The non-limiting example of suitable polyisocyanate comprises aromatic isocyanate, aliphatic isocyanate, carbodiimide-modified polyisocyanate and their combination.

[0019] "Aromatic polyisocyanate" is a polyisocyanate containing one or more aromatic rings. Non-limiting examples of suitable aromatic polyisocyanates include isomers of methylene diphenyl diisocyanate (MDI), such as 4,4-MDI, 2,4-MDI and 2,2'-MDI; or modified MDI, such as carbodiimide-modified MDI, allophanate-modified MDI; isomers of toluene diisocyanate (TDI), such as 2,4-TDI, 2,6-TDI; isomers of naphthalene diisocyanate (NDI), such as 1,5-NDI; and combinations thereof.

[0020] "Aliphatic polyisocyanate" refers to a polyisocyanate in which the isocyanate portion (-NCO) is not directly attached to an aromatic ring. Non-limiting examples of suitable aliphatic polyisocyanates include isomers of hexamethylene diisocyanate (HDI), isomers of isophorone diisocyanate (IPDI), isomers of xylene diisocyanate (XDI), other cycloaliphatic isocyanates such as methylene bis-cyclohexyl isocyanate (hydrogenated MDI) (HMDI) and cyclohexane diisocyanate, and combinations thereof.

[0021] In one embodiment, the polyisocyanate is selected from monoisocyanates, diisocyanates, trimerisocyanates and combinations thereof. In another embodiment, the polyisocyanate is a diisocyanate. In one embodiment, the polyisocyanate is a polyfunctional diisocyanate having at least two isocyanate groups or at least three isocyanate groups. In one embodiment, the polyisocyanate is selected from MDI, TDI, HDI and combinations thereof. In another embodiment, the polyisocyanate is MDI. Commercially available examples of polyisocyanates suitable for use according to the present disclosure include those sold under the trade name ISONATE TM OP 50, ISONATE TM 125M and ISONATE TM M 143 modified MDI is sold as a product of DowMDI, each of which is available from The Dow Chemical Company.

[0022] The polyol used to prepare the vegetable oil polyurethane polyol can be a polyester polyol, a polyether polyol or a combination thereof, preferably a polyether polyol. "Polyether polyol" is a compound that is a polyether and a polyol. Non-limiting examples of suitable polyether polyols include addition products of ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, and their co-addition and graft products; polyether polyols obtained by condensation of polyols or mixtures thereof; and combinations thereof.

[0023] Non-limiting examples of suitable polyether polyols include polypropylene glycol (PPG), polyethylene glycol (PEG), polybutylene glycol, polytetramethylene ether glycol (PTMEG), and combinations thereof. In one embodiment, the polyether polyol is polypropylene glycol (PPG). Non-limiting examples of suitable polypropylene glycols include those sold under the trade name VORANOL TM P-400 is a product sold by The Dow Chemical Company.

[0024] Non-limiting examples of suitable polyether polyols include VORANOL TM 1010L, PPG; and VORANOL TM CP450, glyceryl propoxylated polyether triol, each available from The Dow Chemical Company.

[0025] In one embodiment, the polyether polyol has an Mw of 50 g / mol, or 100 g / mol, or 400 g / mol, or 450 g / mol to 1,000 g / mol, or 1,500 g / mol, or 2,000 g / mol, or 4,000 g / mol, or 5,000 g / mol. In one embodiment, the polyether polyol has a hydroxyl number of 30 mg KOH / g, or 50 mg KOH / g, or 75 mg KOH / g, or 100 mg KOH / g to 115 mg KOH / g, or 125 mg KOH / g, or 150 mg KOH / g, or 200 mg KOH / g, or 300 mg KOH / g, or 350 mg KOH / g, or 400 mg KOH / g, or 450 mg KOH / g, or 500 mg KOH / g. In one embodiment, the polyether polyol has one or both of the following properties: (i) an Mw of 50 g / mol to 5,000 g / mol, or 100 g / mol to 2,000 g / mol, or 400 g / mol to 1,500 g / mol, or 400 g / mol to 1,000 g / mol; and / or (ii) a hydroxyl number of 30 mg KOH / g to 500 mg KOH / g, or 100 mg KOH / g to 400 mg KOH / g, or 100 mg KOH / g to 150 mg KOH / g, or 350 mg KOH / g to 400 mg KOH / g.

[0026] In some embodiments, the vegetable oil containing a hydrophobic polyol having at least two hydroxyl groups may be castor oil or a derivative thereof.

[0027] The vegetable oil polyurethane polyol can be formed by the reaction product of a vegetable oil containing a hydrophobic polyol having at least two hydroxyl groups, a polyisocyanate and a polypropylene glycol. A suitable reaction comprises mixing 8 wt % to 26 wt % of a polyisocyanate, 40 wt % to 50 wt % of a vegetable oil containing a hydrophobic polyol having at least two hydroxyl groups and 40 wt % to 50 wt % of a polypropylene glycol under an inert atmosphere (e.g., nitrogen) at a temperature of 40° C. to 100° C. for 1 to 5 hours (wherein the total weight of the polyisocyanate, the vegetable oil containing a hydrophobic polyol having at least two hydroxyl groups and the polypropylene glycol does not exceed 100 wt %).

[0028] The polyol component comprises 10 to 30 wt %, preferably 11 to 25 wt %, more preferably 11 to 20 wt %, most preferably 11 to 15 wt % of the vegetable oil polyurethane polyol, based on the total weight of the polyol component.

[0029] Polyether polyols

[0030] The polyol component may also include polyether polyols. Non-limiting examples of suitable polyether polyols include addition products of ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, and their co-addition and grafting products; polyether polyols obtained by condensation of polyols or mixtures thereof; and combinations thereof. Non-limiting examples of suitable polyether polyols include polypropylene glycol (PPG), polyethylene glycol (PEG), polybutylene glycol, polytetramethylene ether glycol (PTMEG), and combinations thereof. In one embodiment, the polyether polyol is polypropylene glycol (PPG). Non-limiting examples of suitable polyether polyols include VORANOL TM 1010L, PPG; and VORANOL TM CP450, glyceryl propoxylated polyether triol, each available from The Dow Chemical Company.

[0031] In one embodiment, the polyether polyol has an Mw of 50 g / mol, or 100 g / mol, or 400 g / mol, or 450 g / mol to 1,000 g / mol, or 1,500 g / mol, or 2,000 g / mol, or 4,000 g / mol, or 5,000 g / mol. In one embodiment, the polyether polyol has a hydroxyl number of 30 mg KOH / g, or 50 mg KOH / g, or 75 mg KOH / g, or 100 mg KOH / g to 115 mg KOH / g, or 125 mg KOH / g, or 150 mg KOH / g, or 200 mg KOH / g, or 300 mg KOH / g, or 350 mg KOH / g, or 400 mg KOH / g, or 450 mg KOH / g, or 500 mg KOH / g. In one embodiment, the polyether polyol has one or both of the following properties: (i) an Mw of 50 g / mol to 5,000 g / mol, or 100 g / mol to 2,000 g / mol, or 400 g / mol to 1,500 g / mol, or 400 g / mol to 1,000 g / mol; and / or (ii) a hydroxyl number of 30 mg KOH / g to 500 mg KOH / g, or 100 mg KOH / g to 400 mg KOH / g, or 100 mg KOH / g to 150 mg KOH / g, or 350 mg KOH / g to 400 mg KOH / g.

[0032] The polyol component comprises 5 to 20 wt %, preferably 7 to 18 wt %, more preferably 9 to 15 wt %, even more preferably 10 to 14 wt % of the polyether polyol, based on the total weight of the polyol component.

[0033] Chain Extender

[0034] The polyol component may optionally include a chain extender. Non-limiting examples of suitable chain extenders include glycerol; trimethylolpropane; diethylene glycol; propylene glycol; 2-methyl-1,3-propanediol; 1,4-butanediol (1,4-BDO); ​​and combinations thereof, preferably 1,4-BDO. The polyol component comprises 1 wt % to 20 wt %, preferably 2 wt % to 15 wt %, more preferably 4 wt % to 10 wt %, even more preferably 2 wt % to 6 wt % of a chain extender, preferably 1,4-BDO, based on the total weight of the polyol component.

[0035] The polyol component may optionally contain moisture scavengers, catalysts, flame retardants, rheology modifiers, and fillers as are known in the art.

[0036] Isocyanate prepolymer

[0037] Isocyanate prepolymers of the present disclosure include the reaction product of polyisocyanates and non-dimer acid-based polyester polyols. For various embodiments, the isocyanate prepolymer is the reaction product of 35 wt % to 95 wt % of polyisocyanates and 65 wt % to 5 wt % of non-dimer acid-based polyester polyols, wherein the wt % is based on the gross weight of the isocyanate prepolymer, and the wt % of polyisocyanates and non-dimer acid-based polyester polyols is no more than 100 wt %. Preferably, the isocyanate prepolymer is the reaction product of 55 wt % to 85 wt % of polyisocyanates and 45 wt % to 15 wt % of non-dimer acid-based polyester polyols, wherein the wt % is based on the gross weight of the isocyanate prepolymer, and the wt % of polyisocyanates and non-dimer acid-based polyester polyols is no more than 100 wt %. More preferably, the isocyanate prepolymer is the reaction product of 60 wt % to 80 wt % of a polyisocyanate and 40 wt % to 20 wt % of a non-dimer acid based polyester polyol, wherein the wt % is based on the total weight of the isocyanate prepolymer and the wt % of the polyisocyanate and the non-dimer acid based polyester polyol does not exceed 100 wt % in total.

[0038] Polyisocyanate

[0039] The polyisocyanate can be chemically reacted with the non-dimer acid based polyester polyol to form a prepolymer. Non-limiting examples of suitable polyisocyanates include aromatic isocyanates, aliphatic isocyanates, carbodiimide modified polyisocyanates, and combinations thereof, each as described herein.

[0040] Non-limiting examples of suitable aromatic polyisocyanates include polymeric MDI and isomers of MDI, such as 4,4-MDI, 2,4-MDI and 2,2'-MDI; or modified MDI, such as polycarbodiimide-modified diphenylmethane diisocyanate and allophanate-modified MDI; toluene diisocyanate, isomers of toluene diisocyanate (TDI), such as 2,4-TDI, 2,6-TDI; isomers of naphthalene diisocyanate (NDI), such as 1,5-NDI; and combinations thereof.

[0041] Non-limiting examples of suitable aliphatic polyisocyanates include isomers of HDI, isophorone diisocyanate, IPDI, XDI, other cycloaliphatic isocyanates such as 4,4'-methylene dicyclohexyl diisocyanate, methylene dicyclohexyl isocyanate (hydrogenated MDI or HMDI), and cyclohexane diisocyanate, and combinations thereof.

[0042] In one embodiment, the polyisocyanate is selected from monoisocyanates, diisocyanates, trimer isocyanates and combinations thereof. In another embodiment, the polyisocyanate is diisocyanates. In one embodiment, the polyisocyanate is selected from MDI, TDI, HDI and combinations thereof. In another embodiment, the polyisocyanate is MDI. In one embodiment, the polyisocyanate is selected from carbodiimide-modified MDI, carbodiimide-modified TDI, carbodiimide-modified HDI and combinations thereof. In another embodiment, the polyisocyanate is carbodiimide-modified MDI.

[0043] For various embodiments, the polyisocyanate can be selected from the group consisting of polycarbodiimide-modified diphenylmethane diisocyanate, MDI, TDI, isophorone diisocyanate, 4,4'-methylene dicyclohexyl diisocyanate, polymeric diphenylmethane diisocyanate, and combinations thereof. In one embodiment, the polyisocyanate is polycarbodiimide-modified diphenylmethane diisocyanate.

[0044] In one embodiment, the polyisocyanate has an NCO content of not less than 10%, preferably not less than 15%, preferably not less than 20%.For the various embodiments, the isocyanate prepolymer has an isocyanate content of 10 wt % to 29 wt %, as measured according to ASTM D5155.

[0045] The polyisocyanate component comprises 35 to 95 wt %, preferably 45 to 80 wt %, more preferably 55 to 85 wt %, even more preferably 60 to 80 wt % of the isocyanate prepolymer, based on the total weight of the isocyanate prepolymer.

[0046] Non-dimer acid-based polyester polyol

[0047] "Non-dimer acid-based polyester polyols" are polyester polyols containing units derived from primary polyols, non-dimer acid dicarboxylic acids, and aliphatic monocarboxylic acids. In one embodiment, the non-dimer acid-based polyester polyol is the reaction product of (i) a primary polyol having a hydroxyl functionality of at least 3 and a weight average molecular weight of 800 g / mol or less, (ii) a C4 to C20 non-dimer acid dicarboxylic acid, and (iii) a C10 to C20 aliphatic monocarboxylic acid. For various embodiments, the aliphatic monocarboxylic acid and the primary polyol have a molar ratio of greater than 0.9:1 to 6.5:1 (monocarboxylic acid: primary polyol), and the aliphatic monocarboxylic acid is present in the isocyanate prepolymer in a range of greater than 7.2 wt % to 55 wt % based on the total weight of the isocyanate prepolymer.

[0048] The non-dimer acid-based polyester polyol can be formed by reacting a primary polyol, a non-dimer acid dicarboxylic acid, and an aliphatic monocarboxylic acid (each as provided herein), wherein the reaction mixture may include 10% to 30% by weight of a primary polyol, 5% to 30% by weight of a non-dimer acid dicarboxylic acid, and 50% to 75% by weight of an aliphatic monocarboxylic acid, wherein the reaction mixture comprising the primary polyol, the non-dimer acid dicarboxylic acid, and the aliphatic monocarboxylic acid totals 100% by weight. Preferably, the reaction mixture comprises 15% to 27% by weight of a primary polyol, 10% to 25% by weight of a non-dimer acid dicarboxylic acid, and 50% to 75% by weight of an aliphatic monocarboxylic acid, wherein the reaction mixture comprising the primary polyol, the non-dimer acid dicarboxylic acid, and the aliphatic monocarboxylic acid totals 100% by weight. Most preferably, the reaction mixture comprises 17 to 25 weight percent primary polyol, 12 to 22 weight percent non-dimer acid dicarboxylic acid, and 53 to 72 weight percent aliphatic monocarboxylic acid, wherein the reaction comprising the primary polyol, non-dimer acid dicarboxylic acid, and aliphatic monocarboxylic acid totals 100 weight percent.

[0049] For various embodiments, a reaction mixture comprising a primary polyol, a non-dimer acid dicarboxylic acid, and an aliphatic monocarboxylic acid may be mixed at a temperature heated to 90° C. to 250° C. The acid number of the reaction mixture is preferably less than 10, wherein a catalyst may be used in the reaction mixture. Suitable catalysts include, for example, titanium (IV) butoxide, tetra-n-butyl orthotitanate, and titanium (IV) tert-butoxide.

[0050] For the various embodiments, the non-dimer acid based polyester polyol has a hydroxyl functionality of 1.8 to 2.3.For the various embodiments, the non-dimer acid based polyester polyol has an acid value of 5 mg KOH / g or less, as measured according to ASTM D974.

[0051] The non-dimer acid-based polyester polyol component comprises 65 to 5 wt %, preferably 55 to 20 wt %, more preferably 45 to 15 wt %, even more preferably 40 to 20 wt % of the isocyanate prepolymer based on the total weight of the isocyanate prepolymer.

[0052] Primary polyols

[0053] For various embodiments, the primary polyol has a functionality of at least 3 and a weight average molecular weight of 800 g / mol or less. For various embodiments, the primary polyol is selected from the group consisting of glycerol, diglycerol, triglycerol, trimethylolpropane, di(trimethylolpropane), pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, derivatives thereof (such as alkoxylates), or combinations thereof. The polyol may include two or more embodiments disclosed herein.

[0054] Non-dimerized dicarboxylic acid

[0055] Non-limiting examples of suitable non-dimer acid dicarboxylic acids include aliphatic acids, aromatic acids and combinations thereof. Preferably, non-dimer acid dicarboxylic acids are C4 to C20 non-dimer acid dicarboxylic acids. More preferably, non-dimer acid dicarboxylic acids are C4 to C10 non-dimer acid dicarboxylic acids. Non-limiting examples of suitable aromatic dicarboxylic acids used as non-dimer acid dicarboxylic acids include phthalic acid, isophthalic acid and terephthalic acid. Non-limiting examples of suitable aliphatic dicarboxylic acids used as non-dimer acid dicarboxylic acids include cyclohexane dicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, itaconic acid, suberic acid, 2-methylsuccinic acid, 3,3-diethylglutaric acid and 2,2-dimethylsuccinic acid. As used herein, the term "acid" also includes any anhydride of the acid. Saturated aliphatic and / or aromatic acids are also suitable for use as non-dimer acid dicarboxylic acids, such as adipic acid or isophthalic acid. For the various embodiments, the non-dimer acid dicarboxylic acid is selected from the group consisting of adipic acid, isophthalic acid, and combinations thereof.

[0056] In one embodiment, the non-dimer acid dicarboxylic acid has four, or five, or six to seven, or eight, or nine, or ten carbon atoms. In another embodiment, the non-dimer acid dicarboxylic acid has four to ten carbon atoms, or six to eight carbon atoms. In another embodiment, the non-dimer acid dicarboxylic acid has eight carbon atoms.

[0057] The non-dimer acid dicarboxylic acid may include two or more embodiments disclosed herein.

[0058] Aliphatic monocarboxylic acid

[0059] For various embodiments, the aliphatic monocarboxylic acid is a C10-C20 aliphatic monocarboxylic acid. Preferably, the aliphatic monocarboxylic acid is a C12 to C18 aliphatic monocarboxylic acid. For various embodiments, the aliphatic monocarboxylic acid can be selected from the group consisting of oleic acid, stearic acid, lauric acid, and combinations thereof. The non-dimer acid can include two or more embodiments disclosed herein.

[0060] Optional additives

[0061] In one embodiment, the isocyanate prepolymer of the present disclosure comprises a reaction product of a polyisocyanate, a non-dimer acid-based polyester polyol, and optionally an additive. Non-limiting examples of suitable optional additives include adhesion promoters, chain extenders, catalysts, and combinations thereof. Non-limiting examples of suitable adhesion promoters are aminosilanes. Non-limiting examples of suitable chain extenders include glycerol; trimethylolpropane; diethylene glycol; propylene glycol; 2-methyl-1,3-propanediol; and combinations thereof. Non-limiting examples of suitable catalysts include tetra-n-butyl titanate, zinc sulfate, organotin catalysts, and combinations thereof. Optional additives may include two or more embodiments disclosed herein. In one embodiment, the reaction mixture does not include a chain extender.

[0062] The isocyanate prepolymer may optionally contain plasticizers, flame retardants, adhesion promoters, rheology modifiers, fillers, etc. Plasticizers, such as diisononyl phthalate, help reduce skinning that builds up during application of the isocyanate prepolymer.

[0063] Flame retardants such as isopropylated phosphate phenol can help improve fire resistance. Conventional adhesion promoters such as epoxy silanes can also be used. Rheology modifiers such as fumed silica are often included in adhesive compositions to provide thixotropic properties required for different applications. In isocyanate prepolymers, fumed silica with a hydrophobic surface treatment is commonly used as a rheology modifier. Fillers are added to adhesive compositions to increase mechanical strength and reduce costs. The filler can be selected from silica, CaCO 3 , kaolin and talc, and other fillers known in the art.

[0064] The mixture for preparing the reaction product of (i) a polyisocyanate and (ii) a non-dimer acid-based polyester polyol generally comprises 60 to 95 wt %, preferably 65 to 85 wt %, more preferably 70 to 80 wt % of an aromatic isocyanate and 5 to 40 wt %, preferably 15 to 35 wt %, more preferably 20 to 30 wt % of a non-dimer acid-based polyester polyol, based on the total weight of the mixture for preparing the reaction product of (i) a polyisocyanate and (ii) a non-dimer acid-based polyester polyol.

[0065] The isocyanate prepolymer generally comprises 30 to 100 wt %, preferably 35 to 95 wt %, more preferably 40 to 90 wt %, even more preferably 40 to 80 wt % or 50 to 75 wt % or 60 to 75 wt % of the reaction product of (i) a polyisocyanate and (ii) a non-dimer acid-based polyester polyol, based on the total weight of the isocyanate prepolymer, and optionally 0 to 20 wt %, preferably 1 to 10 wt %, more preferably 0.5 to 8 wt %, even more preferably 1 to 5 wt % or 2 to 4 wt % of a plasticizer, 0 to 20 wt %, preferably 0.1 to 10 wt %, more preferably 0.5 to 8 wt %, even more preferably 1 to 5 wt % or 2 to 4 wt % of a plasticizer. % to 8 wt. %, even more preferably 0.8 to 5 wt. % or 1 to 3 wt. % of flame retardants, 0 to 10 wt. %, preferably 1 to 8 wt. %, more preferably 0.5 to 6 wt. %, even more preferably 0.8 to 5 wt. % or 1 to 4 wt. % of adhesion promoters, 0 to 10 wt. %, preferably 0.5 to 8 wt. %, even more preferably 1 to 5 wt. % or 2 to 4 wt. % of rheology modifiers and 0 to 70 wt. %, preferably 5 to 65 wt. %, more preferably 10 to 50 wt. %, even more preferably 18 to 45 wt. % or 20 to 40 wt. % or 20 to 30 wt. % of fillers.

[0066] Polyurethane adhesive

[0067] The polyurethane adhesive contains no or substantially no solvent. In one embodiment, the polyurethane adhesive contains optional conventional additives. The optional additives can be any optional additives disclosed herein, such as plasticizers, chain extenders, flame retardants, adhesion promoters, rheology modifiers, fillers, moisture scavengers, catalysts, etc.

[0068] The polyurethane adhesive is formed by mixing the polyol component and the isocyanate prepolymer under conditions suitable for the reaction of the -NCO groups of the isocyanate prepolymer with the hydroxyl groups of the polyol component. In one embodiment, the polyol component and the isocyanate prepolymer are combined and mixed at a temperature of 15°C to 55°C via a static mixing device or a dynamic mixing device.

[0069] The isocyanate index or ("NCO index") is the molar ratio of the amount of isocyanate groups in the isocyanate prepolymer to the amount of hydroxyl groups in the polyol component. Isocyanate groups can be measured according to ASTM D2572. The NCO index is calculated according to the following equation (2):

[0070]

[0071] In one embodiment, the polyurethane adhesive has an NCO index of 1.00, or 1.05, or 1.10, or 1.15 to 1.85, or 1.60, or 1.50, or 1.40. In another embodiment, the polyurethane adhesive has an NCO index of 1.05 to 1.85, or 1.10 to 1.60, or 1.15 to 1.50, or 1.15 to 1.40.

[0072] In one embodiment, the polyurethane adhesive comprises a polyol component and an isocyanate prepolymer in an isocyanate prepolymer:polyol component volume ratio of 120:100 to 80:100, or 115:100 to 90:100, or 110:100 to 95:100, or 105:100 to 98:100. The polyurethane adhesive may include two or more embodiments disclosed herein.

[0073] Multi-layer structure

[0074] The present disclosure provides a multilayer structure. The multilayer structure includes a first substrate, a second substrate and an adhesive layer between the first substrate and the second substrate. The adhesive layer is formed by the polyurethane adhesive provided herein. The first substrate and the second substrate may be the same or different. It should be understood that the description of "substrate" herein refers to the first substrate and the second substrate respectively and / or collectively.

[0075] The non-limiting example of suitable second substrate is film. The film can be a monolayer film or a multilayer film. The multilayer film comprises two or more layers. In one embodiment, the film is a monolayer film with one and only one layer. In one embodiment, the film includes a layer containing components selected from the following components: ethylene-based polymers (PE), propylene-based polymers (PP), polyamides (such as nylon), polyesters, ethylene vinyl alcohol (EVOH) copolymers, polyethylene terephthalate (PET), ethylene vinyl acrylate (EVA) copolymers, ethylene methyl acrylate copolymers, ethylene ethyl acrylate copolymers, ethylene butyl acrylate copolymers, ethylene acrylic acid copolymers, ethylene methacrylic acid copolymers, ethylene acrylic acid ionomers, methacrylic acid ionomers, maleic anhydride grafted ethylene-based polymers, polylactic acid (PLA), polystyrene, metal foil, cellulose, cellophane, nonwoven fabrics and combinations thereof. Each layer of the multilayer film can be formed by the same component or by different components.

[0076] In one embodiment, the film comprises a layer comprising a metal foil. A non-limiting example of a suitable metal foil is aluminum foil.

[0077] In one embodiment, the film is a monolayer film having a single layer, which is an ethylene-based polymer layer. In another embodiment, the film is a monolayer film having a single layer, which is a polyethylene layer.

[0078] The substrate, and further the membrane, is a continuous structure having two opposing surfaces.

[0079] In one embodiment, the substrate has a thickness of 5 μm, or 10 μm, or 12 μm, or 15 μm, or 20 μm, or 21 μm to 23 μm, or 24 μm, or 25 μm, or 30 μm, or 35 μm, or 40 μm, or 45 μm, or 50 μm, or 100 μm, or 150 μm, or 200 μm, or 250 μm, or 300 μm, or 350 μm, or 400 μm, or 450 μm, or 500 μm.

[0080] In one embodiment, the substrate excludes cellulose based substrates such as paper and wood.

[0081] In one embodiment, the first substrate is a monolayer film having a single layer which is a PE layer; and the second substrate is a film having a layer which is a metal foil layer.

[0082] The film may include two or more embodiments disclosed herein. The first substrate may include two or more embodiments disclosed herein. The second substrate may include two or more embodiments disclosed herein.

[0083] The polyurethane adhesive is applied between the first substrate and the second substrate, such as using a Nordmeccanica LaboCombi 400 laminator. Non-limiting examples of suitable application methods include brushing, pouring, spraying, coating, rolling, spreading and injecting. In one embodiment, the polyurethane adhesive is applied between the first substrate and the second substrate at a temperature of 20°C, or 30°C, or 40°C to 50°C, or 60°C, or 70°C, or 80°C, or 90°C.

[0084] In one embodiment, the polyurethane adhesive is uniformly applied between the first substrate and the second substrate. "Uniform application" is continuous (rather than discontinuous) on the surface of the substrate and has a layer of the composition of the same or substantially the same thickness over the entire surface of the substrate. In other words, the composition uniformly applied to the substrate directly contacts the substrate surface, and the composition is coextensive with the substrate surface.

[0085] In one embodiment, the polyurethane adhesive is cured in an oven at a temperature of 10° C., 20° C. or 35° C. to 40° C., or 45° C. or 50° C. In one embodiment, the polyurethane adhesive is cured at a temperature of 20° C. to 30° C., preferably 25° C., for 1 to 2 days, or 4 days, or 7 days or 10 days.

[0086] In one embodiment, the first substrate is a monolayer film having a single layer as the metal foil layer, and the second substrate is a monolayer film having a single layer as the metal foil layer, and the multilayer structure has a lap shear strength of 7 MPa, or 7.5 MPa, or 8 MPa to 15 MPa, or 13 MPa, or 12 MPa, and / or has a cross tensile strength of 6.5 MPa, or 7.0 MPa, or 7.5 MPa to 15 MPa, or 13 MPa, or 12 MPa.

[0087] In one embodiment, the first substrate is a monolayer film having a single layer as a metal foil layer, and the second substrate is a film having a layer as a metal foil layer, and the multilayer structure has an average value of adhesive shear strength at the 3σ level on lap joints of >7MPa or 7.5MPa, or 8MPa to 15MPa, or 13MPa, or 12MPa, and an average value of adhesive tensile strength at the 3σ level on butt joints of 6.5MPa, or 6.7MPa, or 7.0MPa, or 7.5MPa to 15MPa, or 13MPa, or 12MPa.

[0088] Various embodiments of the present disclosure also include batteries containing the polyurethane adhesives of the present disclosure. Examples include lithium ion batteries as known in the art.

[0089] By way of example and not limitation, some embodiments of the present disclosure will now be described in detail in the following examples.

[0090] Example

[0091] The examples below are provided for illustration only and are not intended to define or restrict the embodiments in any way. In the Examples (IE) and Comparative Examples (CE), various terms and names of materials are used, including, for example, the following:

[0092] Table 1. Materials

[0093]

[0094]

[0095] Synthesis of dimer acid / 2-methyl-1,3-propanediol polyester polyol-1 (DMP-PE). 50 g (g) of 2-methyl-1,3-propanediol, 233.8 g of dimer acid ( 1001) is loaded into a 500 ml glass reactor and mixed thoroughly. Heat the mixture to 100°C. When the raw materials turn into liquid, then start stirring. Control the temperature at an appropriate location and monitor the temperature throughout the process. If the top temperature of the glass condenser rises to above 103°C, start cooling the reactor as quickly as possible. When the reaction temperature rises to 220°C and the top temperature drops below 100°C, slowly start vacuum over 30 minutes to 30 mm Hg. Check the acid value every 30 minutes. Add catalyst TBT was added until the acid value of the reaction mixture was less than 10, and then the reaction system was kept under 30 mm Hg vacuum for more than 1 hour until the OH value reached the theoretical value. The resulting mixture was cooled to 60°C-70°C and the final product, DMP-PE, was collected.

[0096] Synthesis of Adipic Acid / 2-Methyl-1,3-Propanediol Based Polyester Polyol (AMP-PE). 100 g of 2-methyl-1,3-propanediol and 146.4 g of adipic acid were reacted as described for (DFMP-PE). The final product was collected as AMP-PE.

[0097] Synthesis of adipic acid / trimethylolpropane / oleic polyester polyol (ATO-PE-1). 97.4 g trimethylolpropane, 80.5 g adipic acid, 205.0 g oleic acid were reacted as described for (DFMP-PE). The final product was collected as ATO-PE-1.

[0098] Synthesis of adipic acid / trimethylolpropane / oleic polyester polyol (ATO-PE-2). 101.4 g trimethylolpropane, 83.8 g adipic acid, 198.0 g oleic acid were reacted as described for (DFMP-PE). The final product was collected as ATO-PE-2.

[0099] Synthesis of adipic acid / 2-methyl-1,3-propanediol / trimethylolpropane / oleic polyester polyol (ATO-PE-3). 69.9 g trimethylolpropane, 126.7 g adipic acid, 147.1 g oleic acid, 47.0 g 2-methyl-1,3-propanediol were reacted as described for (DFMP-PE). The final product was collected as ATO-PE-3.

[0100] Synthesis of adipic acid / trimethylolpropane / oleic acid / stearic acid based polyester polyol (ATOS-PE). 95.5 g trimethylolpropane, 78.4 g adipic acid, 100.5 g oleic acid, 101.2 g stearic acid were reacted as described for (DFMP-PE). The final product was collected as ATOS-PE.

[0101] Synthesis of Adipic Acid / Pentaerythritol / Oleic Acid-Based Polyester Polyol (APO-PE) 64.9 g of pentaerythritol, 44.0 g of adipic acid, 269.1 g of oleic acid were reacted as described for (DFMP-PE) The final product was collected as APO-PE.

[0102] Synthesis of adipic acid / isophthalic acid / trimethylolpropane / oleic polyester polyol (AITO-PE). 96.0 g trimethylolpropane, 39.5 g adipic acid, 44.9 g isophthalic acid, 202.0 g oleic acid were reacted as described for (DFMP-PE). The final product was collected as AITO-PE.

[0103] Synthesis of Phosphate-Modified Polyols

[0104] The synthesis of phosphate-modified polyols is described in Example 5 of WO2015 / 168670A1, the entire contents of which are incorporated herein by reference. A 1 liter (L) multi-necked round-bottom flask was dried in an oven with dry N 2 Rinse for 30 minutes and then install VORANOL TM CP 450 polyether polyol (150 g) was placed in a N 2 Purge. Load the syringe with 115% polyphosphoric acid (PPA) (4 g, ALDRICH CHEMICAL Co.). Add PPA dropwise to the polyether polyol under vigorous stirring. Minimal temperature rise is observed. Heat the reactor contents to 100°C for 1 hour and then cool to 45°C. Add ISONATE TM 125M polyisocyanate (50 g). Due to the heat of reaction, the temperature rises to about 95°C. In addition, the viscosity increases and a yellow color is present. Then, the reactor is brought to 65°C and ethyl acetate (40 g) is added to reduce the viscosity and improve stirring. After 1 hour, the reactor is cooled and the contents are packaged (viscosity: 42,750 mPa.s).

[0105] Synthesis of castor oil polyurethane polyol (COP polyol): COP polyol was synthesized in a 1,000 ml glass reactor using a conventional polyurethane prepolymer preparation method. 12 g of ISONATE TMOP 50 was loaded into the reactor and kept at 60°C under nitrogen protection, then 44 g of castor oil and 44 g of VORANOL TM P 400 is loaded into the reactor to be used with ISONATE TM OP50 was mixed. The temperature was slowly increased to 80°C and maintained for 2 hours. The obtained COP polyol (vegetable oil polyurethane polyol) was packed into a well-sealed container with nitrogen protection for further use.

[0106] Synthesis of NCO-terminated prepolymer of DMP-PE (Pre-DMP): 75 g ISONATE TM 143L was loaded into a 1,000ml glass reactor and kept at 60°C under nitrogen protection, and then 25g of DMP-PE was loaded into the reactor to mix with ISONATE TM 143L mixed. The temperature was slowly raised to 80°C and maintained for 2 to 3 hours until the NCO content reached the theoretical value. The obtained Pre-DMP was placed in a well-sealed container with nitrogen protection for further use.

[0107] Synthesis of NCO-terminated prepolymer of AMP-PE (Pre-AMP) :

[0108] 75g ISONATE TM 143L was loaded into a 1,000ml glass reactor and kept at 60°C under nitrogen protection, and then 25g AMP-PE was loaded into the reactor to mix with ISONATE TM 143L mixed. The temperature was slowly raised to 80°C and maintained for 2 to 3 hours until the NCO content reached the theoretical value. The obtained Pre-AMP was packed into a well-sealed container with nitrogen protection for further use.

[0109] Synthesis of NCO-terminated prepolymer of ATO-PE-1 (Pre-ATO1): 75 g ISONATE TM 143L was loaded into a 1,000ml glass reactor and kept at 60°C under nitrogen protection, and then 25g of ATO-PE-1 was loaded into the reactor to mix with ISONATE TM 143L mixed. The temperature was slowly raised to 80°C and maintained for 2 to 3 hours until the NCO content reached the theoretical value. The obtained Pre-ATO1 was placed in a well-sealed container with nitrogen protection for further use.

[0110] Synthesis of NCO-terminated prepolymer of ATO-PE-2 (Pre-ATO2): 75 g ISONATE TM143L was loaded into a 1,000ml glass reactor and kept at 60°C under nitrogen protection, and then 25g of ATO-PE-2 was loaded into the reactor to mix with ISONATE TM 143L mixed. The temperature was slowly raised to 80°C and maintained for 2 to 3 hours until the NCO content reached the theoretical value. The obtained Pre-ATO2 was loaded into a well-sealed container with nitrogen protection for further use.

[0111] Synthesis of NCO-terminated prepolymer of ATO-PE-3 (Pre-ATO3): 75 g ISONATE TM 143L was loaded into a 1,000ml glass reactor and kept at 60°C under nitrogen protection, and then 25g of ATO-PE-3 was loaded into the reactor to mix with ISONATE TM 143L mixed. The temperature was slowly raised to 80°C and maintained for 2 to 3 hours until the NCO content reached the theoretical value. The obtained Pre-ATO3 was loaded into a well-sealed container with nitrogen protection for further use.

[0112] Synthesis of NCO-terminated prepolymer of ATOS-PE (Pre-ATOS): 75 g ISONATE TM 143L was loaded into a 1,000ml glass reactor and kept at 60°C under nitrogen protection, and then 25g ATOS-PE was loaded into the reactor to mix with ISONATE TM 143L mixed. The temperature was slowly raised to 80°C and maintained for 2 to 3 hours until the NCO content reached the theoretical value. The obtained Pre-ATOS was loaded into a well-sealed container with nitrogen protection for further use.

[0113] Synthesis of NCO-terminated prepolymer of APO-PE (Pre-APO): 75 g ISONATE TM 143L was loaded into a 1,000ml glass reactor and kept at 60°C under nitrogen protection, and then 25g of APO-PE was loaded into the reactor to mix with ISONATE TM 143L mixed. The temperature was slowly raised to 80°C and maintained for 2 to 3 hours until the NCO content reached the theoretical value. The obtained Pre-APO was packed into a well-sealed container with nitrogen protection for further use.

[0114] Synthesis of NCO-terminated prepolymer of AITO-PE (Pre-AITO): 75 g ISONATE TM143L was loaded into a 1,000ml glass reactor and kept at 60°C under nitrogen protection, and then 25g of AITO-PE was loaded into the reactor to mix with ISONATE TM 143L mixed. The temperature was slowly raised to 80°C and maintained for 2 to 3 hours until the NCO content reached the theoretical value. The obtained Pre-AITO was loaded into a well-sealed container with nitrogen protection for further use.

[0115] Inventive Examples (IE) were designed in two steps: (1): Isocyanate prepolymer (part, which can meet the moisture resistance requirements) is summarized in Table 2. (2) Adhesive examples including Part A and Part B are summarized in Table 3.

[0116] CE-A shows good hydrophobicity, but the cost and cycle time for preparing polyester polyols are high (20 hours). CE-B shows poor moisture resistance (only 7 hours). IE-1 shows good moisture resistance (14 hours), shorter time for preparing polyester (11 hours) and lower cost relative to CE-A due to the introduction of aliphatic monocarboxylic acid (e.g., 10.1 wt% incorporation based on isocomponent). CE-C shows that the prepolymer cannot be synthesized due to the molar ratio between aliphatic monocarboxylic acid and low molecular weight and high functional polyols being reduced from 1.00 (IE-1) to 0.93. Therefore, CE-C provides a limit on the molar ratio between aliphatic monocarboxylic acid and polyol. CE-D shows poor moisture resistance of isocyanate prepolymers due to the reduction of aliphatic monocarboxylic acid from 10.1 wt% incorporation based on isocyanate prepolymer (IE-1) to 7.2 wt% based on isocyanate prepolymer. Therefore, CE-D provides a limit on the weight ratio of aliphatic monocarboxylic acid in isocyanate prepolymers.

[0117] IE-2, IE-3 and IE-4 exhibit good moisture resistance as well as short preparation times and low raw material costs for the polyester polyols due to the significant inclusion of long-chain and aliphatic monocarboxylic acids (9.9% to 11.2% by weight, based on the isocyanate prepolymer) and the molar ratio between aliphatic monocarboxylic acids and polyols (1.00 to 2.00).

[0118] Table 2. Isocyanate prepolymers

[0119]

[0120] The adhesive formulations are summarized in Table 3, with details in the corresponding examples of Part A and Part B. The volumetric mixing ratios and stoichiometric ratios were calculated and listed in Table 3. CE-E showed unsatisfactory lap shear strength (10.14 MPa < 10.5 MPa) due to the introduction of dimer acid in the applied isocyanate of CE-A. CE-F showed improved and satisfactory lap shear strength (10.87 MPa > 10.5 MPa) due to the replacement of dimer acid with adipic acid, but the moisture resistance was unacceptable due to its application of the isocyanate prepolymer of CE-B. CE-G showed satisfactory lap shear strength (11.72 MPa > 10.5 MPa) due to the replacement of dimer acid with adipic acid, but the moisture resistance of the applied isocyanate prepolymer CE-D was poor due to the reduced inclusion of long chain and aliphatic monocarboxylic acids. IE-5 shows good lap shear strength (11.91 MPa>10.5 MPa) and good moisture resistance of the applied isocyanate prepolymer IE-1 due to the use of adipic acid instead of dimer acid, as well as shorter time to prepare polyester polyols and low cost of polyester polyols due to the use of aliphatic monocarboxylic acids (10.1 wt. % incorporation based on isocomponents). By comparing IE-5 with CE-H, the removal of phosphate-modified polyols results in poor lap shear strength (9 MPa<10.5 MPa). Therefore, phosphate-modified polyols help achieve high lap shear strength. By comparing IE-5 with CE-I, the removal of COP polyols (vegetable oil polyurethane polyols) results in poor lap shear strength (10.24 MPa<10.5 MPa). Therefore, in order to achieve high lap shear strength, vegetable oil polyurethane polyols should be present in the formulation. IE-6, IE-7 and IE-8 incorporating IE-2, IE-3 and IE-4 isocyanate prepolymers exhibit good lap shear strength (12.00-14.29 MPa>10.5 MPa) due to the presence of phosphate-modified polyols and COP polyols (vegetable oil polyurethane polyols), wherein the applied isocyanate prepolymers exhibit good moisture resistance due to the significant presence of aliphatic monocarboxylic acids (9.9 wt % to 11.2 wt % based on the isocyanate prepolymers) and the molar ratio between aliphatic monocarboxylic acids and high-functional short polyols (1.00-2.00), as well as shorter preparation times for polyester polyols and low raw material costs for polyester polyols.

[0121] Table 3. Adhesive Examples

[0122]

[0123] Experimental Procedure

[0124] Isocyanate prepolymers (partial) were prepared according to the following procedure: Step 1 - Charge NCO-terminated prepolymers into a container; then, add other liquid components (e.g., DINP, KH560); Step 2 - Apply vacuum and mix at a moderate stirring rate for 30 minutes; Step 3 - Add CaCO 3 into a container; apply vacuum after incorporating the powder; mix at high stirring rate for 30 minutes; Step 4 - R974 was charged into a container; vacuum was applied after powder incorporation; mixing was performed at a high stirring rate for 1 hour; Step 5 - the temperature bath was set to 80°C; mixing was maintained at a medium to low stirring rate for 30 minutes to maintain the temperature; Step 6 - the temperature bath was set to 20°C to cool to below 40°C.

[0125] The tack-free time was tested according to the following procedure (ASTM C679-03): Take 10 g of the isocyanate prepolymer (the portion in the 50 ml plastic beaker) and place the beaker in an oven at 45% relative humidity and 23°C. Start time recording. Take out the beaker periodically and gently touch the surface of the isocyanate prepolymer B with a plastic stick. As the reaction between the isocyanate prepolymer and moisture increases, the surface viscosity increases. When the surface of the isocyanate prepolymer is not sticky, stop time recording. This duration is recorded as the tack-free time of the isocyanate prepolymer.

[0126] The polyol component (Part A) was prepared according to the following procedure: Step 1 - Castor oil, phosphate modified polyol, COP polyol (vegetable oil polyurethane polyol), Voranol TM CP450 and 1,4-BDO were charged into a container; Step 2 - the mixture was heated to 80°C; vacuum was applied and mixed at a moderate stirring rate for 1 hour to degas; Step 3 - CaCO 3 into a container, apply vacuum after incorporating the powder; mix at a high stirring rate for 15 minutes; Step 4 - molecular sieve 3A is loaded into the container; apply vacuum after incorporating the powder; mix at a high stirring rate for 15 minutes; Step 5 - R974 was charged into a container; vacuum was applied after incorporation of the powder; mixing was performed at a high stirring rate for 1 hour; Step 6 - Cooling to <40°C.

[0127] Test Method :

[0128] Acid value was measured according to ASTM D974.

[0129] The lap joint test specimens were prepared using the following procedure: (1) The substrate was made of 3003 aluminum alloy with a size of 25 mm × 12.5 mm. (2) The substrate surface was cleaned by wiping with ethanol. (3) A 25 mm × 12 mm bonding area was masked by using a pressure-sensitive tape. (4) Part A and Part B of the adhesive were mixed and placed in a high-speed mixer at 1,000 rpm for 1 minute to ensure thorough mixing. (5) 0.5 g to 1.5 g of adhesive was applied to the bonding area of ​​the substrate. Two copper wires with a diameter of 0.2 mm were placed to control the thickness of the adhesive. (6) Along the length direction, another masked substrate with the same bonding area in head-to-head contact was stacked. The bonding surface was squeezed and tightened with two side-by-side clamps. (7) The adhesive was cured at 25°C for 7 days.

[0130] Butt joint test specimens were prepared based on the following procedure: (1) The substrate was made of 3003 aluminum alloy with dimensions of 60 mm high and 15 mm diameter. (2) The substrate surface was cleaned by wiping with ethanol. (3) Part A and Part B of the adhesive were mixed and placed in a high-speed mixer at 1,000 rpm for 1 minute to ensure thorough mixing. (4) 0.5 g to 1 g of adhesive was applied on the flat surface of the substrate. Two copper wires with a diameter of 0.25 mm were placed to control the thickness of the adhesive. (5) Another clean substrate was stacked with the flat surfaces bonded together. The stacked substrates were kept vertically so that the bonding surfaces could be constantly tightened by gravity. (6) The adhesive was cured at 25°C for 7 days.

[0131] The test specimens were assembled on the fixture of an Instron testing machine (model: Instron 5566), and the shear strength of the lap joint and the tensile strength of the butt joint were tested at a strain rate of 5 mm / min.

Claims

1. A polyurethane adhesive, the polyurethane adhesive comprising: an isocyanate prepolymer, the isocyanate prepolymer comprising the reaction product of: 35 weight percent (wt%) to 95 wt% of a polyisocyanate; and 65 wt% to 5 wt% of a non-dimer acid-based polyester polyol, wherein the wt% is based on the total weight of the isocyanate prepolymer, and the wt% of the polyisocyanate and the non-dimer acid-based polyester polyol together do not exceed 100 wt%; wherein the non-dimer acid-based polyester polyol comprises the reaction product of a primary polyol having a hydroxyl functionality of at least 3 and a weight average molecular weight of 800 g / mol or less, a C4 to C20 non-dimer acid dicarboxylic acid, and a C10 to C20 aliphatic monocarboxylic acid, wherein the aliphatic monocarboxylic acid and the primary polyol have a molar ratio greater than 0.9:1 to 6.5:1 (monocarboxylic acid:primary polyol), and the aliphatic monocarboxylic acid is present in the isocyanate prepolymer in a range greater than 7.2 wt% to 55 wt% based on the total weight of the isocyanate prepolymer; and a polyol component, the polyol component comprising: 20 wt% to 80 wt% of a hydrophobic polyol; 3 wt% to 15 wt% of a phosphate ester-modified polyol; and 10 wt% to 30 wt% of a vegetable oil polyurethane polyol, wherein the wt% is based on the total weight of the polyol component, and the wt% of the hydrophobic polyol, the phosphate ester-modified polyol, and the vegetable oil polyurethane polyol together do not exceed 100 wt%.

2. The polyurethane adhesive according to claim 1, wherein the non-dimer acid-based polyester polyol has a hydroxyl functionality of 1.8 to 2.

3.

3. The polyurethane adhesive according to any one of claims 1 to 2, wherein the non-dimer acid-based polyester polyol has an acid value of 5 mg KOH / g or less, as measured according to ASTM D974.

4. The polyurethane adhesive according to any one of claims 1 to 3, wherein the aliphatic monocarboxylic acid is selected from the group consisting of oleic acid, stearic acid, lauric acid, and combinations thereof.

5. The polyurethane adhesive according to any one of claims 1 to 4, further comprising 5 wt% to 20 wt% of a polyether polyol.

6. The polyurethane adhesive according to any one of claims 1 to 5, wherein the hydrophobic polyol is castor oil.

7. The polyurethane adhesive according to any one of claims 1 to 6, wherein the polyurethane adhesive has an isocyanate index of 1.05 to 1.

85.

8. The polyurethane adhesive according to any one of claims 1 to 7, wherein the non-dimer acid dicarboxylic acid is selected from the group consisting of adipic acid, isophthalic acid, and combinations thereof.

9. A multi-layer structure, the multi-layer structure comprising: a first substrate; a second substrate; and An adhesive layer between the first substrate and the second substrate, the adhesive layer being formed of a polyurethane adhesive according to any one of claims 1 to 8, wherein the first substrate is a single-layer film having a single layer as a metal foil layer, and the second substrate is a single-layer film having a single layer as a metal foil layer.

10. A battery, the battery comprising a polyurethane adhesive according to any one of claims 1 to 8.

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