A moisture-curing polyurethane hot melt adhesive and its preparation method

Abstract

This invention provides a moisture-curing polyurethane hot melt adhesive and its preparation method. The moisture-curing polyurethane hot melt adhesive is prepared from the following raw materials in parts by weight: 40-80 parts of crystalline polyester polyol, 20-50 parts of liquid polyester polyol or biomass polyester polyol, 10-30 parts of highly crystalline polyol, 20-50 parts of polyether polyol, 20-50 parts of isocyanate, and 20-50 parts of thermoplastic resin. This moisture-curing polyurethane hot melt adhesive has high bonding strength, appropriate melt viscosity, and good water resistance.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane hot melt adhesive technology, specifically relating to a moisture-curing polyurethane hot melt adhesive and its preparation method. Background Technology

[0002] Moisture-curing polyurethane hot melt adhesives are solid adhesives made by melt-mixing -NCO end-group prepolymers with thermoplastic resins, fillers, catalysts, antioxidants, etc. When used, they need to be heated to a molten state before being coated or sprayed onto the substrate surface. After cooling, they form an initial physical bond with the adherends and further react with the surface of the adherends and moisture in the air for deeper curing and enhanced adhesion. They can be widely used for bonding electronic and electrical appliances, wood, metal, fabrics, and other substrates. In recent years, with the increasing demands for aesthetics and comfort in clothing, hot melt adhesives can not only replace the underwires of traditional bras to improve comfort but also replace traditional sewing processes, making clothing more aesthetically pleasing, such as seamless underwear and seamless yoga wear.

[0003] When using hot melt adhesives to replace traditional sewing, adhesive strength is the primary concern. Furthermore, for ease of application when bonding textiles, the hot melt adhesive must also have an appropriate melt viscosity. Since everyday underwear and other intimate apparel are typically washed daily, in addition to ensuring fabric adhesive strength and appropriate melt viscosity, the polyurethane hot melt adhesive for underwear must also have good wash resistance, maintaining its adhesive strength even after multiple washes. Additionally, the hardness of the hot melt adhesive is also a crucial factor affecting the comfort of the underwear.

[0004] Chinese patent document CN118496806A discloses a high-elasticity polyurethane hot melt adhesive for textile fabrics with a resilience rate of 98.2%. However, organic solvents such as acetone are added during the synthesis process, and its fabric peel strength is only 36.8 N / 25 mm, indicating poor adhesive strength. Chinese patent document CN114989772A discloses a low-hardness polyurethane hot melt adhesive for textiles and its preparation method. However, the prepared polyurethane hot melt adhesive has excessive viscosity, resulting in glue dripping / sticking during use, making it unsuitable for underwear adhesive dispensing equipment and significantly impacting production efficiency.

[0005] Therefore, existing polyurethane hot melt adhesives for textile fabrics still have problems such as poor bonding strength, inappropriate melt viscosity, and insufficient water resistance. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a moisture-curing polyurethane hot melt adhesive and its preparation method, which has high bonding strength, appropriate melt viscosity and good water resistance.

[0007] To address the above problems, one aspect of the present invention provides a moisture-curing polyurethane hot melt adhesive, the raw materials of which comprise the following components in parts by weight:

[0008] 40-80 parts of crystalline polyester polyol, 20-50 parts of liquid polyester polyol or biomass polyester polyol, 10-30 parts of highly crystalline polyol, 20-50 parts of polyether polyol, 20-50 parts of isocyanate, and 20-50 parts of thermoplastic resin.

[0009] Preferably, the raw materials for its preparation include the following components in parts by mass:

[0010] 51-74 parts of crystalline polyester polyol, 34-42 parts of liquid polyester polyol or biomass polyester polyol, 15-25 parts of highly crystalline polyol, 30-35 parts of polyether polyol, 32-40.6 parts of isocyanate, and 30-40 parts of thermoplastic resin.

[0011] Preferably, the raw materials for preparing the highly crystalline polyol include 1,6-hexanediol, 1,12-dodecanediol, 2-methyl-2-propyl-1,3-propanediol, and adipic acid; the molar ratio of 1,6-hexanediol, 1,12-dodecanediol, 2-methyl-2-propyl-1,3-propanediol, and adipic acid is 0.6–0.8:0.6–0.8:0.5–0.7:0.5–1.5.

[0012] Preferably, the crystalline polyester polyol is one or more of the following: polyadipate polyol with a number average molecular weight of 2500-4500, polyphthalate polyol with a number average molecular weight of 2500-4500, and polycarbonate polyol with a number average molecular weight of 2500-4500.

[0013] The liquid polyester polyol is one or more of polyadipate polyols with a number average molecular weight of 1500 to 6500 and polycarbonate polyols with a number average molecular weight of 1500 to 6500.

[0014] The polyether polyol is polypropylene glycol with a number average molecular weight of 1000-2000;

[0015] The isocyanate is diphenylmethane-4,4'-diisocyanate;

[0016] The thermoplastic resin is an acrylic resin with a number average molecular weight of 30,000 to 40,000.

[0017] Preferably, the raw materials for its preparation further include the following components in parts by mass:

[0018] 1-3 parts of adhesion promoter;

[0019] The adhesion promoter is one or more of (3-methacryloyloxy-2-hydroxypropoxy)propylbis(trimethylsiloxy)methylsilane, 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane, and tri(trimethylsiloxy)silane.

[0020] Preferably, the raw materials for its preparation further include the following components in parts by mass:

[0021] Catalyst 0.1–0.5 parts;

[0022] The catalyst is one or more of dibutyltin dilaurate, stannous octoate, dimorpholino diethyl ether, and triethylamine.

[0023] Preferably, the raw materials for its preparation further include the following components in parts by mass:

[0024] Antioxidant 1-3 parts;

[0025] The antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris[2,4-di-tert-butylphenyl]phosphite, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 2,6-di-tert-butyl-4-methylphenol.

[0026] Another aspect of the present invention provides a method for preparing the above-mentioned moisture-curing polyurethane hot melt adhesive, comprising the following steps:

[0027] The crystalline polyester polyol, liquid polyester polyol or biomass polyester polyol, highly crystalline polyol, polyether polyol, and thermoplastic resin are mixed and vacuum dehydrated at 110–130°C for 1.5–3 hours; then isocyanate is added and reacted at 90–125°C for 1–3 hours under an inert atmosphere; then vacuum degassing is performed at 110–130°C to obtain the moisture-curing polyurethane hot melt adhesive.

[0028] Preferably, the method for preparing the highly crystalline polyol includes the following steps:

[0029] 1,6-hexanediol, 1,12-dodecanediol and 2-methyl-2-propyl-1,3-propanediol were mixed and dehydrated under vacuum for 0.5 to 1.5 hours. Then adipic acid was added, and the mixture was reacted at 130 to 150°C for 1 to 3 hours under an inert atmosphere to obtain the highly crystalline polyol.

[0030] Preferably, it further includes:

[0031] After the isocyanate is added, an adhesion promoter, a catalyst, and an antioxidant are also added, and the reaction is continued at 90–125°C for 0.5–1 hour.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] In the moisture-curing polyurethane hot melt adhesive of the present invention, the polar groups (such as ester groups, hydroxyl groups, etc.) on the molecular chains of crystalline polyester polyols can form hydrogen bonds and other polar interactions. These polar groups can interact with the polar groups on the surface of the adherend, thereby enhancing the intermolecular interaction forces, improving the cohesive strength of the material, and thus improving the peel strength. Furthermore, the crystalline portions of the crystalline polyester polyols and the added highly crystalline polyols have an ordered molecular arrangement structure. This ordered structure further improves the overall strength and stability of the material, making the molecular chains less prone to damage under peel force, thereby further enhancing the peel strength. The surface drying time of hot melt adhesives made from pure crystalline polyester polyols is the same as the cooling time. Hot melt adhesives made from pure liquid polyester polyols, however, must react with moisture in the air to solidify before drying. Therefore, hot melt adhesives made from pure liquid polyester polyols have a significantly longer surface drying time than those made from pure crystalline polyester polyols. This invention combines crystalline and liquid polyester polyols to obtain polyurethane hot melt adhesives with different surface drying times. This is highly suitable for the dispensing process of seamless underwear, allowing for the selection of polyurethane hot melt underwear adhesives with different surface drying times to suit different dispensing processes, effectively matching enterprise production and maximizing production efficiency. The highly crystalline polyol added in this invention has good crystallinity and can shorten the surface drying time more effectively compared to polyols such as polyhexyl adipate. The present invention also incorporates thermoplastic resin and polyether polyol. The thermoplastic resin has a certain degree of elasticity, while polyether polyol has weaker hydrogen bonds between its molecules compared to polyester polyol, and its molecules can rotate, resulting in lower cohesive strength. Therefore, the corresponding hot melt adhesive has lower hardness, which ensures that the polyurethane hot melt adhesive has low hardness while also having low viscosity. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] A first aspect of this invention provides a moisture-curing polyurethane hot melt adhesive, the raw materials of which comprise the following components in parts by weight:

[0036] 40-80 parts of crystalline polyester polyol, 20-50 parts of liquid polyester polyol or biomass polyester polyol, 10-30 parts of highly crystalline polyol, 20-50 parts of polyether polyol, 20-50 parts of isocyanate, and 20-50 parts of thermoplastic resin.

[0037] In the moisture-curing polyurethane hot melt adhesive of this invention, the polar groups (such as ester groups, hydroxyl groups, etc.) on the molecular chains of crystalline polyester polyols can form hydrogen bonds and other polar interactions. These polar groups can interact with the polar groups on the surface of the adherend, thereby enhancing the intermolecular interaction forces, improving the cohesive strength of the material, and thus improving the peel strength. Furthermore, the crystalline portions of the crystalline polyester polyols and the added highly crystalline polyols have an ordered molecular arrangement structure. This ordered structure further improves the overall strength and stability of the material, making the molecular chains less prone to damage under peel force, thereby further enhancing the peel strength. The surface drying time of hot melt adhesives made from pure crystalline polyester polyols is the same as the cooling time. Hot melt adhesives made from pure liquid polyester polyols, however, must react with moisture in the air to solidify before drying. Therefore, hot melt adhesives made from pure liquid polyester polyols have a significantly longer surface drying time than those made from pure crystalline polyester polyols. This invention combines crystalline and liquid polyester polyols to obtain polyurethane hot melt adhesives with different surface drying times. This is highly suitable for the dispensing process of seamless underwear, allowing for the selection of polyurethane hot melt underwear adhesives with different surface drying times to suit different dispensing processes, effectively matching enterprise production and maximizing production efficiency. The highly crystalline polyol added in this invention has good crystallinity and can shorten the surface drying time more effectively compared to polyols such as polyhexyl adipate. The present invention also incorporates thermoplastic resin and polyether polyol. The thermoplastic resin has a certain degree of elasticity, while polyether polyol has weaker hydrogen bonds between its molecules compared to polyester polyol, and its molecules can rotate, resulting in lower cohesive strength. Therefore, the corresponding hot melt adhesive has lower hardness, which ensures that the polyurethane hot melt adhesive has low hardness while also having low viscosity.

[0038] Preferably, the raw materials for preparing the moisture-curing polyurethane hot melt adhesive include the following components in parts by weight:

[0039] The composition comprises 51-74 parts crystalline polyester polyol, 34-42 parts liquid polyester polyol or biomass polyester polyol, 15-25 parts highly crystalline polyol, 30-35 parts polyether polyol, 32-40.6 parts isocyanate, and 30-40 parts thermoplastic resin. Within the above-mentioned preferred mass fraction range, the moisture-curing polyurethane hot melt adhesive can exhibit better adhesive strength, more suitable viscosity, and better water washability.

[0040] In some embodiments, the raw materials for preparing the highly crystalline polyol include 1,6-hexanediol, 1,12-dodecanediol, 2-methyl-2-propyl-1,3-propanediol, and adipic acid. These four raw materials can form a well-ordered molecular structure, which helps to form a more ordered crystal structure, thereby improving the crystallinity of the obtained polyol; furthermore, the strong intermolecular forces help the molecules to be better arranged during crystallization, thus improving crystallinity. This invention uses the above four raw materials to prepare a highly crystalline polyol, which, when added to hot melt adhesive raw materials, can significantly improve the adhesive strength of the hot melt adhesive and shorten its surface drying time.

[0041] Preferably, in the raw materials for preparing the highly crystalline polyol, the molar ratio of 1,6-hexanediol, 1,12-dodecanediol, 2-methyl-2-propyl-1,3-propanediol, and adipic acid is 0.6–0.8:0.6–0.8:0.5–0.7:0.5–1.5. More preferably, the molar ratio of 1,6-hexanediol, 1,12-dodecanediol, 2-methyl-2-propyl-1,3-propanediol, and adipic acid is 0.7:0.7:0.6:1.

[0042] In some embodiments, the crystalline polyester polyol is one or more of the following: adipate polyols, phthalate polyols, and polycarbonate polyols with a number average molecular weight of 2500-4500. Specifically, the number average molecular weight of the adipate polyol, phthalate polyol, and polycarbonate polyol can be, but is not limited to, 2500, 3000, 4000, and 4500, as long as its number average molecular weight is between 2500 and 4500 and it is a crystalline polyester polyol.

[0043] In some embodiments, the polyadipate polyol used in the crystalline polyester polyol can be any one or a mixture of several of poly(1,4-butanediol adipate) and poly(1,6-hexanediol adipate).

[0044] In some embodiments, the polyphthalate polyol used in the crystalline polyester polyol may be poly(1,4-butanediol) phthalate diol.

[0045] In some embodiments, the polycarbonate polyol used in the crystalline polyester polyol may be polycarbonate-1,6-hexanediol diol.

[0046] In some embodiments, the liquid polyester polyol is one or more of polyadipate polyols with a number average molecular weight of 1500 to 6500. Specifically, the number average molecular weight of the polyadipate polyol can be, but is not limited to, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 6500, etc., as long as its number average molecular weight is between 1500 and 6500 and it is a liquid polyester polyol.

[0047] In some embodiments, the polyadipate polyol used in the liquid polyester polyol can be one or more of poly(ethylene adipate diol), poly(butylene adipate diol), and poly(1,4-butanediol neopentyl glycol adipate diol).

[0048] In some embodiments, the biomass polyester polyol is a biomass-derived polyester polyol, specifically one or more of the fully bio-based polyols with model numbers XCP-B2000-J, XCP-B2000-S, XCP-B2000-JS, XCP-B2000-BS, and XCP-B2000-BJS, or one or more of the partially bio-based polyols with model numbers XCP-2000P, XCP-2000B-S, XCP-2000E-JS, and XCP-2000B-JS.

[0049] In some embodiments, the polyether polyol is polypropylene glycol with a number average molecular weight of 1000 to 2000. Specifically, it can be polypropylene glycol with a number average molecular weight of 1000, 1500, 2000, etc.

[0050] In some embodiments, the isocyanate may be diphenylmethane-4,4'-diisocyanate (CAS No. 101-68-8) or other types of isocyanates.

[0051] In some embodiments, the thermoplastic resin is an acrylic resin with a number average molecular weight of 30,000 to 40,000. Specifically, it can be an acrylic resin with a number average molecular weight of 30,000, 35,000, 40,000, etc.

[0052] Preferably, the raw materials for preparing the moisture-curing polyurethane hot melt adhesive further include the following components in parts by weight: 1 to 3 parts of an adhesion accelerator. More preferably, the adhesion accelerator is 1 to 2 parts. The adhesion accelerator can further improve the adhesive strength of the polyurethane hot melt adhesive.

[0053] In some embodiments, the adhesion promoter is one or more of (3-methacryloyloxy-2-hydroxypropoxy)propylbis(trimethylsiloxy)methylsilane (CAS No. 69861-02-5), 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (CAS No. 26115-70-8), 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane (CAS No. 7538-44-5), and tris(trimethylsiloxy)silane (CAS No. 1873-89-8). Appropriate selection of adhesion promoters can further improve the adhesive strength of polyurethane hot melt adhesives. This invention has found that using the above-mentioned adhesion promoters can significantly improve the adhesive strength and washability of polyurethane hot melt adhesives.

[0054] Preferably, the raw materials for preparing the moisture-curing polyurethane hot melt adhesive further include the following components in parts by weight: 0.1 to 0.5 parts of catalyst. More preferably, the catalyst is 0.2 to 0.4 parts.

[0055] In some embodiments, the catalyst is one or more of dibutyltin dilaurate (CAS No. 77-58-7), stannous octoate (CAS No. 301-10-0), dimorpholino diethyl ether (CAS No. 6425-39-4), and triethylamine (CAS No. 121-44-8).

[0056] Preferably, the raw materials for preparing the moisture-curing polyurethane hot melt adhesive further include the following components in parts by weight: 1 to 3 parts of antioxidant. More preferably, the antioxidant is 1 to 2 parts.

[0057] In some embodiments, the antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (CAS No. 128-37-0), tris[2,4-di-tert-butylphenyl]phosphite (CAS No. 31570-04-4), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS No. 2082-79-3), and 2,6-di-tert-butyl-4-methylphenol (CAS No. 128-37-0).

[0058] Another aspect of this invention provides a method for preparing the above-mentioned moisture-curing polyurethane hot melt adhesive, comprising the following steps:

[0059] The crystalline polyester polyol, liquid polyester polyol or biomass polyester polyol, highly crystalline polyol, polyether polyol, and thermoplastic resin are mixed and vacuum dehydrated at 110–130°C for 1.5–3 hours; then isocyanate is added and reacted at 90–125°C for 1–3 hours under an inert atmosphere; then vacuum degassing is performed at 110–130°C to obtain the moisture-curing polyurethane hot melt adhesive.

[0060] In some embodiments, the method for preparing the highly crystalline polyol includes the following steps:

[0061] 1,6-hexanediol, 1,12-dodecanediol and 2-methyl-2-propyl-1,3-propanediol were mixed and dehydrated under vacuum for 0.5 to 1.5 hours. Then adipic acid was added, and the mixture was reacted at 130 to 150°C for 1 to 3 hours under an inert atmosphere to obtain the highly crystalline polyol.

[0062] In some embodiments, the preparation method of the moisture-curing polyurethane hot melt adhesive further includes:

[0063] After the isocyanate is added, an adhesion promoter, a catalyst, and an antioxidant are also added, and the reaction is continued at 90–125°C for 0.5–1 hour.

[0064] Example 1

[0065] In this embodiment, the highly crystalline polyol used was prepared from 42 parts by mass of 1,6-hexanediol, 72 parts by mass of 1,12-dodecanediol, 40 parts by mass of 2-methyl-2-propyl-1,3-propanediol, and 73 parts by mass of adipic acid. That is, the molar ratio of 1,6-hexanediol, 1,12-dodecanediol, 2-methyl-2-propyl-1,3-propanediol, and adipic acid was 0.7:0.7:0.6:1.

[0066] The moisture-curing polyurethane hot melt adhesive of this embodiment is prepared from the following components in parts by weight:

[0067] 58 parts of poly(1,4-butanediol adipate) diol with a number average molecular weight of 3500, 16 parts of poly(1,6-hexanediol adipate) diol with a number average molecular weight of 3500, 34 parts of poly(diethylene glycol adipate) diol with a number average molecular weight of 2000, 15 parts of highly crystalline polyol, 30 parts of polypropylene glycol with a number average molecular weight of 2000, 32 parts of 4-4'-diphenylmethane diisocyanate, 30 parts of acrylic resin with a number average molecular weight of 35000, 1 part of (3-methacryloyloxy-2-hydroxypropoxy)propylbis(trimethylsiloxy)methylsilane, 0.2 parts of dimorpholino diethyl ether, and 1 part of tris[2,4-di-tert-butylphenyl]phosphite.

[0068] The preparation method of the moisture-curing polyurethane hot melt adhesive in this embodiment includes the following steps:

[0069] 1. 1,6-hexanediol, 1,12-dodecanediol and 2-methyl-2-propyl-1,3-propanediol were added to a reaction vessel and heated to 120°C for vacuum dehydration for 1 hour (vacuum degree of -0.095MPa). After the vacuum was broken, adipic acid was added and the reaction was carried out at 140°C for 2 hours under nitrogen protection to obtain a highly crystalline polyol.

[0070] 2. According to the selected mass proportions, add crystalline polyester polyol, liquid polyester polyol, highly crystalline polyol, polyether polyol, and thermoplastic resin to the reactor, heat to 120°C, and dehydrate under vacuum for 2 hours with stirring. The vacuum degree is -0.095MPa.

[0071] 3. Purge with nitrogen to break the vacuum, add isocyanate, and react at 125°C for 1.5 hours under nitrogen protection.

[0072] 4. Add adhesion promoter, catalyst and antioxidant, and continue stirring at 100°C for 0.5 hours.

[0073] 5. Heat to 125℃, degas under vacuum, and discharge to obtain the moisture-curing polyurethane hot melt adhesive.

[0074] Example 2

[0075] In this embodiment, the highly crystalline polyol used is the same as that in Example 1.

[0076] The moisture-curing polyurethane hot melt adhesive of this embodiment is prepared from the following components in parts by weight:

[0077] 30 parts of poly(1,4-butanediol adipate) diol with a number average molecular weight of 3500, 22 parts of poly(1,6-hexanediol adipate) diol with a number average molecular weight of 3500, 40 parts of poly(diethylene glycol adipate) diol with a number average molecular weight of 2000, 20 parts of highly crystalline polyol, 35 parts of polypropylene glycol with a number average molecular weight of 2000, 38.2 parts of 4-4'-diphenylmethane diisocyanate, 34 parts of acrylic resin with a number average molecular weight of 35000, 2 parts of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane, 0.4 parts of dimorpholino diethyl ether, and 2 parts of tris[2,4-di-tert-butylphenyl]phosphite.

[0078] The preparation method of the moisture-curing polyurethane hot melt adhesive in this embodiment includes the following steps:

[0079] 1. The preparation steps for highly crystalline polyols are the same as in Example 1.

[0080] 2. According to the selected mass proportions, add crystalline polyester polyol, liquid polyester polyol, highly crystalline polyol, polyether polyol, and thermoplastic resin to the reactor, heat to 110°C, and dehydrate under vacuum for 2.5 hours with stirring. The vacuum degree is -0.095MPa.

[0081] 3. Purge with nitrogen to break the vacuum, add isocyanate, and react at 110°C for 2 hours under nitrogen protection.

[0082] 4. Add adhesion promoter, catalyst and antioxidant, and continue stirring at 105°C for 0.5 hours.

[0083] 5. Heat to 110℃, degas under vacuum, and discharge to obtain the moisture-curing polyurethane hot melt adhesive.

[0084] Example 3

[0085] In this embodiment, the highly crystalline polyol used is the same as that in Example 1.

[0086] The moisture-curing polyurethane hot melt adhesive of this embodiment is prepared from the following components in parts by weight:

[0087] 15 parts of poly(1,4-butanediol adipate) diol with a number average molecular weight of 3500, 36 parts of poly(1,6-hexanediol adipate) diol with a number average molecular weight of 3500, 42 parts of poly(diethylene glycol adipate) diol with a number average molecular weight of 2000, 25 parts of highly crystalline polyol, 30 parts of polypropylene glycol with a number average molecular weight of 2000, 40.6 parts of 4-4'-diphenylmethane diisocyanate, 40 parts of acrylic resin with a number average molecular weight of 35000, 2 parts of 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 0.3 parts of dimorpholino diethyl ether, and 1 part of tris[2,4-di-tert-butylphenyl] phosphite.

[0088] The preparation method of the moisture-curing polyurethane hot melt adhesive in this embodiment includes the following steps:

[0089] 1. The preparation steps for highly crystalline polyols are the same as in Example 1.

[0090] 2. According to the selected mass proportions, add crystalline polyester polyol, liquid polyester polyol, highly crystalline polyol, polyether polyol, and thermoplastic resin to the reactor, heat to 130°C, and vacuum dehydrate for 1.5 hours with stirring, with a vacuum degree of -0.095MPa.

[0091] 3. Purge with nitrogen to break the vacuum, add isocyanate, and react at 130°C for 1 hour under nitrogen protection.

[0092] 4. Add adhesion promoter, catalyst and antioxidant, and continue stirring at 110°C for 0.5 hours.

[0093] 5. Heat to 110℃, degas under vacuum, and discharge to obtain the moisture-curing polyurethane hot melt adhesive.

[0094] Example 4

[0095] In this embodiment, the highly crystalline polyol used is the same as that in Example 1.

[0096] The moisture-curing polyurethane hot melt adhesive of this embodiment is prepared from the following components in parts by weight:

[0097] 55 parts of poly(1,4-butanediol adipate) diol with a number average molecular weight of 3500, 25 parts of poly(1,6-hexanediol adipate) diol with a number average molecular weight of 3500, 50 parts of poly(diethylene glycol adipate) diol with a number average molecular weight of 2000, 10 parts of highly crystalline polyol, 20 parts of polypropylene glycol with a number average molecular weight of 2000, 50 parts of 4-4'-diphenylmethane diisocyanate, 20 parts of acrylic resin with a number average molecular weight of 35000, 1 part of 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 0.5 parts of dimorpholino diethyl ether, and 1 part of tris[2,4-di-tert-butylphenyl] phosphite.

[0098] The preparation method of the moisture-curing polyurethane hot melt adhesive in this embodiment is the same as that in Example 1.

[0099] Example 5

[0100] In this embodiment, the highly crystalline polyol used is the same as that in Example 1.

[0101] The moisture-curing polyurethane hot melt adhesive of this embodiment is prepared from the following components in parts by weight:

[0102] 30 parts of poly(1,4-butanediol adipate) diol with a number average molecular weight of 3500, 10 parts of poly(1,6-hexanediol adipate) diol with a number average molecular weight of 3500, 20 parts of poly(diethylene glycol adipate) diol with a number average molecular weight of 2000, 30 parts of highly crystalline polyol, 50 parts of polypropylene glycol with a number average molecular weight of 2000, 20 parts of 4-4'-diphenylmethane diisocyanate, 50 parts of acrylic resin with a number average molecular weight of 35000, 3 parts of 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 0.1 parts of dimorpholino diethyl ether, and 3 parts of tris[2,4-di-tert-butylphenyl] phosphite.

[0103] The preparation method of the moisture-curing polyurethane hot melt adhesive in this embodiment is the same as that in Example 1.

[0104] Example 6

[0105] The moisture-curing polyurethane hot melt adhesive of this embodiment is the same as that of Example 1 in terms of other components, content, and preparation method. The difference is that the poly(ethylene adipate diol) with a number average molecular weight of 2000 is replaced with a fully bio-based polyol of model XCP-B2000-JS, manufactured by Asahikawa Chemical (Suzhou) Co., Ltd.

[0106] Example 7

[0107] The moisture-curing polyurethane hot melt adhesive in this embodiment is the same as that in Example 2 in terms of other components, content, and preparation method. The difference is that the poly(ethylene adipate diol) with a number average molecular weight of 2000 is replaced with a fully bio-based polyol of model XCP-B2000-JS, manufactured by Asahikawa Chemical (Suzhou) Co., Ltd.

[0108] Example 8

[0109] The moisture-curing polyurethane hot melt adhesive in this embodiment is the same as that in Example 3 in terms of other components, content, and preparation method. The difference is that the poly(ethylene adipate diol) with a number average molecular weight of 2000 is replaced with a fully bio-based polyol of model XCP-B2000-JS, manufactured by Asahikawa Chemical (Suzhou) Co., Ltd.

[0110] Example 9

[0111] The moisture-curing polyurethane hot melt adhesive of this embodiment has the same components, content, and preparation method as in Example 1, except that the adhesive promoter is replaced with 3-isocyanate-propyltrimethoxysilane.

[0112] Comparative Example 1

[0113] The moisture-curing polyurethane hot melt adhesive in this comparative example is the same as that in Example 1 in terms of other components, content, and preparation method, except that the highly crystalline polyol is replaced with poly(1,4-butanediol adipate) diol with a number average molecular weight of 3500.

[0114] Comparative Example 2

[0115] The moisture-curing polyurethane hot melt adhesive in this comparative example is the same as that in Example 2 in terms of other components, content, and preparation method, except that the highly crystalline polyol is replaced with poly(1,4-butanediol adipate) diol with a number average molecular weight of 3500.

[0116] Comparative Example 3

[0117] The moisture-curing polyurethane hot melt adhesive in this comparative example is the same as that in Example 3 in terms of other components, content, and preparation method, except that the highly crystalline polyol is replaced with poly(1,4-butanediol adipate) diol with a number average molecular weight of 3500.

[0118] Comparative Example 4

[0119] The moisture-curing polyurethane hot melt adhesive in this comparative example is the same as that in Example 1 in terms of other components, content, and preparation method, except that (3-methacryloyloxy-2-hydroxypropoxy)propylbis(trimethylsiloxy)methylsilane is not added, that is, no adhesion promoter is added.

[0120] Comparative Example 5

[0121] The moisture-curing polyurethane hot melt adhesive in this comparative example is the same as that in Example 2 in terms of other components, content, and preparation method, except that 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is not added, that is, no adhesion promoter is added.

[0122] Comparative Example 6

[0123] The moisture-curing polyurethane hot melt adhesive in this comparative example is the same as that in Example 3 in terms of other components, content, and preparation method, except that 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione is not added, that is, no adhesion promoter is added.

[0124] The melt viscosity, surface drying time, peel strength, and washability of the moisture-curing polyurethane hot melt adhesives obtained in the above embodiments and comparative examples were tested. The test methods are as follows, and the test results are shown in Table 1.

[0125] Melt viscosity: Refer to GB / T10247-2008 to test the melt viscosity of hot melt adhesive at 130℃.

[0126] Surface drying time: Refer to GB / T1729-1979, and test the surface drying time at 25℃ using the finger touch method.

[0127] Peel strength: Adhesive was applied to the fabric using a dispensing machine, and the fabric was pressed together with another piece of fabric using a hot press (hot pressing conditions: 120℃ for 12 seconds). The mixture was then cured at 25℃ / 50%RH for 24 hours. The sample was cut into strips with a width of 25mm, and the tensile rate was 50mm / min with a peel angle of 180 degrees. The test result is the average value of 3 parallel strips.

[0128] Washability: The hot-pressed fabric was cured at 25℃ / 50%RH for 24 hours and then placed in a washing machine with 3-5kg of other fabrics. 25mL of laundry detergent was added, and the fabric was machine washed at 60℃ for 50 minutes, repeated 10 times. After washing, the fabric sample was dried in a 50℃ oven. After drying, it was placed at 25℃ / 50%RH for 8 hours and a peel test was performed. The average value of 3 parallel strips was taken, and the ratio of the test result to the original peel strength was the washability.

[0129] Table 1

[0130]

[0131] As can be seen from the performance comparison of the examples and comparative examples in Table 1, the peel strength of Examples 1-3 with added highly crystalline polyol is higher than that of the comparative examples 1-3 without added highly crystalline polyol, and their corresponding surface drying time is also shorter. The peel strength and washability of Examples 1-3 with added adhesion promoter are better than those of the comparative examples 4-6 without added adhesion promoter. The performance of Examples 6-8 is not significantly different from that of Examples 1-3, indicating that it is feasible to replace part of the polyester polyol with bio-based polyester polyol. Compared with Example 9, Example 1 has better peel strength and washability. Among them, Example 3 has the best performance, providing excellent adhesive strength (i.e., high peel strength) while achieving surface drying in a short time, excellent washability, good mechanical properties, and moderate melt viscosity, avoiding glue dripping / hanging during dispensing. The embodiments with different surface drying times described in this invention can be well matched with the actual production processes of end-user companies, which helps to improve the production efficiency of enterprises. In addition, the bio-based polyester polyol used in this invention can reduce the dependence on petrochemical raw materials and is more green and environmentally friendly.

[0132] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A moisture-curing polyurethane hot melt adhesive, characterized in that, Its preparation raw materials include the following components in parts by mass: 40-80 parts of crystalline polyester polyol, 20-50 parts of liquid polyester polyol or biomass polyester polyol, 10-30 parts of highly crystalline polyol, 20-50 parts of polyether polyol, 20-50 parts of isocyanate, 20-50 parts of thermoplastic resin; 1-3 parts of adhesive accelerator. The raw materials for preparing the highly crystalline polyol include 1,6-hexanediol, 1,12-dodecanediol, 2-methyl-2-propyl-1,3-propanediol, and adipic acid; the molar ratio of 1,6-hexanediol, 1,12-dodecanediol, 2-methyl-2-propyl-1,3-propanediol, and adipic acid is 0.6~0.8: 0.6~0.8:0.5~0.7:0.5~1.

5. The crystalline polyester polyol is one or more of the following: polyadipate polyol with a number average molecular weight of 2500-4500, polyphthalate polyol with a number average molecular weight of 2500-4500, and polycarbonate polyol with a number average molecular weight of 2500-4500. The liquid polyester polyol is one or more of polyadipate polyols with a number average molecular weight of 1500-6500 and polycarbonate polyols with a number average molecular weight of 1500-6500. The polyether polyol is polypropylene glycol with a number average molecular weight of 1000-2000; The thermoplastic resin is an acrylic resin with a number average molecular weight of 30,000 to 40,000. The adhesion promoter is one or more of (3-methacryloyloxy-2-hydroxypropoxy)propylbis(trimethylsilyloxy)methylsilane, 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane, and tri(trimethylsilyloxy)silane.

2. The moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that, Its preparation raw materials include the following components in parts by mass: 51-74 parts of crystalline polyester polyol, 34-42 parts of liquid polyester polyol or biomass polyester polyol, 15-25 parts of highly crystalline polyol, 30-35 parts of polyether polyol, 32-40.6 parts of isocyanate, 30-40 parts of thermoplastic resin; 1-3 parts of adhesive accelerator.

3. The moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that: The isocyanate is diphenylmethane-4,4'-diisocyanate.

4. The moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that, Its preparation raw materials also include the following components in parts by mass: Catalyst 0.1~0.5 parts; The catalyst is one or more of dibutyltin dilaurate, stannous octoate, dimorpholino diethyl ether, and triethylamine.

5. The moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that, Its preparation raw materials also include the following components in parts by mass: Antioxidant 1-3 parts; The antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris[2,4-di-tert-butylphenyl]phosphite, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 2,6-di-tert-butyl-4-methylphenol.

6. A method for preparing a moisture-curing polyurethane hot melt adhesive as described in any one of claims 1-5, characterized in that, Includes the following steps: A mixture of crystalline polyester polyol, liquid polyester polyol or biomass polyester polyol, highly crystalline polyol, polyether polyol, and thermoplastic resin is vacuum dehydrated at 110-130°C for 1.5-3 hours; then isocyanate is added, and the mixture is reacted at 90-125°C for 1-3 hours under an inert atmosphere; an adhesion promoter is added, and the mixture is reacted again at 90-125°C for 0.5-1 hour; finally, the mixture is vacuum degassed at 110-130°C to obtain the moisture-curing polyurethane hot melt adhesive.

7. The preparation method according to claim 6, characterized in that, The method for preparing the highly crystalline polyol includes the following steps: 1,6-hexanediol, 1,12-dodecanediol and 2-methyl-2-propyl-1,3-propanediol were mixed and dehydrated under vacuum for 0.5 to 1.5 hours. Then adipic acid was added and the mixture was reacted at 130 to 150°C for 1 to 3 hours under an inert atmosphere to obtain the highly crystalline polyol.

8. The preparation method according to claim 6, characterized in that, Also includes: After the isocyanate reaction, a catalyst and antioxidant are also added when the adhesion promoter is added.

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