High-solid-content waterborne polyurethane adhesive and preparation method thereof

Abstract

The invention discloses a high-solid-content waterborne polyurethane adhesive and a preparation method thereof. The preparation method comprises the following steps: uniformly mixing polyester polyol, a hydrophilic monomer and a solvent, transferring into an irradiation tube, introducing nitrogen to remove oxygen, sealing and carrying out irradiation treatment; the preparation method comprises the following steps: firstly, adding an antibacterial agent, performing post-treatment to obtain polyester polyol A grafted with the antibacterial agent, recording as PEP-g-HDM, placing the PEP-g-HDM in an oil bath for heating and vacuum dehydration, cooling, then heating in a water bath, adding polyisocyanate and a catalyst for reaction, heating for reaction again, adding deionized water for emulsification after the reaction is finished, stirring in the emulsification process, and emulsifying for 1-2 hours to obtain the antibacterial agent-grafted polyester polyol. The high-curing-amount waterborne polyurethane adhesive is obtained. According to the invention, a radiation grafting technology is adopted to introduce a hydrophilic monomer into a molecular structure of polyester polyol through a covalent bond, the introduction of a branched chain structure not only improves the initial viscosity of the polyurethane hot melt adhesive, but also increases the solid content of a waterborne polyurethane emulsion, and the process is simple, easy to implement and wide in applicability.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a high-solid-content waterborne polyurethane adhesive and a preparation method thereof. Background Art

[0002] Traditional solvent-based polyurethane adhesives have great environmental and health risks due to the use of a large amount of organic solvents in their preparation process. With the strengthening of people's environmental protection awareness, waterborne polyurethanes have developed rapidly. Compared with solvent-based polyurethanes, waterborne polyurethanes are non-toxic, pollution-free, non-flammable, inexpensive, and at the same time maintain the characteristics of high wear resistance, high elasticity, high adhesiveness and good adhesion to various substrates of ordinary solvent-based polyurethane adhesives, and are a "green material" with great development potential.

[0003] Although waterborne polyurethanes have many excellent properties, there are still many deficiencies. Among them, the most important is that the low solid content of waterborne polyurethane emulsions leads to disadvantages such as slow drying and film-forming speed, poor self-thickening property, and low initial adhesion. The solid content of commercially available modified waterborne polyurethane adhesives is generally 15%-35%, which not only increases the transportation and drying costs, but also affects the bonding ability of the resin. Therefore, increasing the solid content of waterborne polyurethanes has become an important research direction at home and abroad. At present, the synthesis of high-solid-content waterborne polyurethanes mainly uses sulfonates as hydrophilic chain extenders, and there are also sulfonates and carboxylates mixed as hydrophilic chain extenders. By introducing hydrophilic ionic groups into the molecular chain structure through molecular design, waterborne polyurethanes with high solid content under low ionic group content are prepared. The introduction of hydrophilic groups into the polyurethane molecular structure provides a new development idea for the research of high-solid-content waterborne polyurethanes.

[0004] In summary, in order to solve the above problems, it is of important application significance to prepare a high-solid-content waterborne polyurethane. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-solid-content waterborne polyurethane adhesive and a preparation method thereof to solve the problems put forward in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A high-solid-content waterborne polyurethane adhesive, including the following steps:

[0007] S1: Mix polyester polyol, hydrophilic monomer, and solvent evenly, transfer them to an irradiation tube, purge with nitrogen to remove oxygen for 15-20 minutes, seal and irradiate; perform post-treatment to obtain polyester polyol A grafted with hydrophilic monomer, denoted as PEP-g-HDM;

[0008] S2: Add PEP-g-HDM into a three-necked flask, then heat it in an oil bath to about 90 - 100 °C for vacuum dehydration for 1 - 2 h. After cooling, heat it to 40 - 50 °C in a water bath, add polyisocyanate and a catalyst, and react for 1 - 2 h. Raise the temperature to 60 - 65 °C and react for another 2 - 3 h. After the reaction is completed, add deionized water for emulsification. During the emulsification process, the rotation speed of the stirring paddle is 1500 - 2000 revolutions per minute, and the emulsification time is 1 - 2 h to obtain an aqueous polyurethane adhesive.

[0009] More preferably, during the irradiation treatment, the radiation source is cobalt-60 or an electron accelerator.

[0010] More preferably, during the irradiation treatment, the absorbed dose is 5 - 20 kGy.

[0011] More preferably, the PEP-g-HDM comprises the following raw materials, by mass: 100 parts of polyester polyol, 5 - 20 parts of hydrophilic monomer, and 30 - 60 parts of solvent;

[0012] The polyurethane adhesive comprises the following raw materials, by mass: 200 - 230 parts of PEP-g-HDM, 260 - 480 parts of polyisocyanate, 2 - 5 parts of catalyst, and 150 - 200 parts of deionized water.

[0013] More preferably, the hydrophilic monomer includes one or more of acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, vinylpyrrolidone, hydroxyethyl acrylate, hydroxypropyl acrylate, and dimethylaminoethyl acrylate.

[0014] More preferably, the polyester polyol includes one or more of polyether diol, polyethylene adipate diol, polyethylene glycol phthalate glycol, polycaprolactone diol, polycarbonate 1,6-hexanediol ester diol, polypropylene glycol, polypropylene oxide triol, tertiary amino polyether tetraol, and polytetrahydrofuran diol;

[0015] The solvent includes one or more of acetone, isopropanol, methanol, ethanol, and N,N-dimethylformamide;

[0016] The polyisocyanate includes one or more of toluene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, dimethylbiphenyl diisocyanate, 1,6-hexamethylene diisocyanate, tetramethyl-m-xylylene diisocyanate, isophorone diisocyanate, methylcyclohexyl diisocyanate, 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and norbornane diisocyanate;

[0017] The catalyst includes one or more of triethylenediamine, bis[2-(N,N-dimethylaminoethyl)] ether, 2-(2-dimethylamino-ethoxy) ethanol, N-ethylmorpholine, dibutyltin dilaurate, and stannous octoate.

[0018] Technical effects and advantages of the present invention: From the perspective of material design, the present invention uses radiation grafting technology to introduce hydrophilic monomers into the molecular structure of polyester polyol through covalent bonds. The introduction of the branched chain structure not only improves the initial adhesion of the polyurethane hot melt adhesive, but also increases the solid content of the aqueous polyurethane emulsion. This process is simple, easy to implement, and has a wide range of applicability. Moreover, the idea of introducing hydrophilic groups into the structure of polyurethane adhesives through covalent bonds proposed in the present invention is not only applicable to polyurethane hot melt adhesives, but also applicable to other hot melt adhesive systems. Specific embodiments

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] Example 1:

[0021] A preparation method of a high-solid-content aqueous polyurethane adhesive includes the following steps:

[0022] S1: Mix 100 parts of polyethylene adipate glycol and 10 parts of acrylic acid evenly with 30 parts of acetone, transfer it to an irradiation tube, deoxygenate with nitrogen for 15 minutes and then seal it, and irradiate it with a cobalt source at an absorbed dose of 5 kGy. After the reaction is completed, evaporate the solvent and unreacted monomers to obtain a polyester polyol grafted with hydrophilic monomers, denoted as PEP-g-HDM.

[0023] S2: Add 200 parts of PEP-g-HDM to a three-necked flask, then heat it to about 90 °C in an oil bath for vacuum dehydration for 2 hours. After cooling, heat it to 40 °C in a water bath and add 100 parts of toluene diisocyanate, 130 parts of dicyclohexylmethane diisocyanate, 30 parts of norbornane diisocyanate, and 2 parts of triethylenediamine, and react for 2 hours. Raise the temperature to 60 °C and continue to react for 2 hours. After the reaction is completed, add 150 parts of deionized water for emulsification. During the emulsification process, the stirring paddle rotates at 2000 revolutions per minute and the emulsification time is 1 hour to obtain an aqueous polyurethane adhesive.

[0024] Example 2:

[0025] A preparation method of a high-solid-content aqueous polyurethane adhesive includes the following steps:

[0026] S1: Mix 50 parts of polyethylene glycol bis(2-hydroxyethyl) phthalate diol, 50 parts of polycaprolactone diol, 5 parts of methacrylic acid with 60 parts of isopropanol uniformly, transfer to an irradiation tube, deoxygenate by passing nitrogen for 20 min and then seal. Irradiate with an accelerator at an absorbed dose of 20 kGy. After the reaction, evaporate the solvent and unreacted monomers to obtain a polyester polyol grafted with hydrophilic monomers, denoted as PEP-g-HDM;

[0027] S2: Add 230 parts of PEP-g-HDM to a three-necked flask, then heat to about 100 °C in an oil bath for vacuum dehydration for 1 h. After cooling, heat to 50 °C in a water bath and add 200 parts of diphenylmethane diisocyanate, 200 parts of naphthalene diisocyanate, 80 parts of terephthalic diisocyanate and 3.5 parts of bis[2-(N,N-dimethylaminoethyl)] ether, and react for 2 h. Raise the temperature to 65 °C and continue to react for 3 h. After the reaction, add 200 parts of deionized water for emulsification. During the emulsification process, the stirring paddle rotates at 1500 rpm and the emulsification time is 2 h to obtain an aqueous polyurethane adhesive.

[0028] Example 3:

[0029] A preparation method of a high-solid-content aqueous polyurethane adhesive, comprising the following steps:

[0030] S1: Mix 20 parts of polycarbonate 1,6-hexanediol ester diol, 80 parts of polypropylene glycol, 10 parts of 2-acrylamido-2-methylpropanesulfonic acid, 10 parts of acrylamide with 50 parts of methanol uniformly, transfer to an irradiation tube, deoxygenate by passing nitrogen for 15 min and then seal. Irradiate with a cobalt source at an absorbed dose of 15 kGy. After the reaction, evaporate the solvent and unreacted monomers to obtain a polyester polyol grafted with hydrophilic monomers, denoted as PEP-g-HDM;

[0031] S2: Add 220 parts of PEP-g-HDM to a three-necked flask, then heat to about 100 °C in an oil bath for vacuum dehydration for 1 h. After cooling, heat to 50 °C in a water bath and add 200 parts of dimethylbiphenyl diisocyanate, 100 parts of 1,6-hexamethylene diisocyanate, 180 parts of tetramethyl-m-xylene diisocyanate and 2 parts of 2-(2-dimethylamino-ethoxy)ethanol, 1.5 parts of N-ethylmorpholine, and react for 2 h. Raise the temperature to 65 °C and continue to react for 3 h. After the reaction, add 180 parts of deionized water for emulsification. During the emulsification process, the stirring paddle rotates at 1500 rpm and the emulsification time is 2 h to obtain an aqueous polyurethane adhesive.

[0032] Example 4:

[0033] A preparation method of a high-solid-content aqueous polyurethane adhesive, comprising the following steps:

[0034] S1: Add 20 parts of polypropylene glycol triol, 80 parts of tertiary amino polyether tetrol, 8 parts of vinyl pyrrolidone, and 7 parts of hydroxyethyl acrylate to 50 parts of ethanol, mix evenly, transfer to an irradiation tube, purge with nitrogen to remove oxygen for 15 min, then seal, and irradiate with a cobalt source at an absorbed dose of 15 kGy. After the reaction, evaporate the solvent and unreacted monomers to obtain a polyester polyol grafted with hydrophilic monomers, denoted as PEP-g-HDM;

[0035] S2: Add 200 parts of PEP-g-HDM to a three-necked flask, then heat in an oil bath to about 90 °C for vacuum dehydration for 1.5 h. After cooling, heat to 50 °C in a water bath, and add 220 parts of dimethylbiphenyl diisocyanate, 110 parts of 1,6-hexamethylene diisocyanate, 150 parts of tetramethylm-xylylene diisocyanate, 2 parts of 2-(2-dimethylamino-ethoxy)ethanol, and 1.5 parts of N-ethylmorpholine, and react for 2 h. Raise the temperature to 65 °C and continue to react for 3 h. After the reaction, add 180 parts of deionized water for emulsification. During the emulsification process, the stirring speed of the stirring paddle is 1500 rpm, and the emulsification time is 2 h to obtain an aqueous polyurethane adhesive.

[0036] Example 5:

[0037] A preparation method of a high-solid-content aqueous polyurethane adhesive, comprising the following steps:

[0038] S1: Add 100 parts of polytetrahydrofuran glycol, 7.5 parts of hydroxypropyl acrylate, and 7.5 parts of dimethylaminoethyl acrylate to 45 parts of N,N-dimethylformamide, mix evenly, transfer to an irradiation tube, purge with nitrogen to remove oxygen for 15 min, then seal, and irradiate with an accelerator at an absorbed dose of 20 kGy. After the reaction, evaporate the solvent and unreacted monomers to obtain a polyester polyol grafted with hydrophilic monomers, denoted as PEP-g-HDM;

[0039] S2: Add 230 parts of PEP-g-HDM to a three-necked flask, then heat in an oil bath to about 95 °C for vacuum dehydration for 1.5 h. After cooling, heat to 50 °C in a water bath, and add 200 parts of isophorone diisocyanate, 100 parts of methylcyclohexyl diisocyanate, 100 parts of 1,4-cyclohexane diisocyanate, 3 parts of dibutyltin dilaurate, and 2.5 parts of stannous octoate, and react for 2 h. Raise the temperature to 65 °C and continue to react for 2 h. After the reaction, add 200 parts of deionized water for emulsification. During the emulsification process, the stirring speed of the stirring paddle is 1500 rpm, and the emulsification time is 2 h to obtain an aqueous polyurethane adhesive.

[0040] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a high-solid-content aqueous polyurethane adhesive, characterized in that: It includes the following steps: S1: Mix polyester polyol, hydrophilic monomer, and solvent evenly, transfer them to an irradiation tube, purge with nitrogen to remove oxygen, seal and perform irradiation treatment, and then perform post-treatment to obtain polyester polyol A grafted with hydrophilic monomer, denoted as PEP-g-HDM; S2: Add PEP-g-HDM to a three-necked flask, then heat to about 90 - 100 °C and vacuum dehydrate for 1 - 2 h. After cooling, when heated to 40 - 50 °C, add polyisocyanate and catalyst and react for 1 - 2 h, then raise the temperature to 60 - 65 °C and react for another 2 - 3 h. After the reaction is completed, add deionized water for emulsification. During the emulsification process, the stirring speed of the stirring paddle is 1500 - 2000 revolutions per minute, and the emulsification time is 1 - 2 h to obtain an aqueous polyurethane adhesive.

2. The preparation method of a high-solid-content waterborne polyurethane adhesive according to claim 1, characterized in that: In step S1, during the irradiation treatment process, the absorbed dose is 5 - 20 kGy.

3. The preparation method of a high-solid-content waterborne polyurethane adhesive according to claim 1, characterized in that: In step S1, the polyester polyol, hydrophilic monomer, and solvent respectively include 100 parts by mass of polyester polyol, 5 - 15 parts by mass of hydrophilic monomer, and 30 - 60 parts by mass of solvent; In step S2, it includes 120 - 190 parts by mass of PEP-g-HDM, 280 - 560 parts by mass of polyisocyanate, 4 - 5.5 parts by mass of catalyst, and 150 - 200 parts of deionized water.

4. The preparation method of a high-solid-content waterborne polyurethane adhesive according to claim 1, characterized in that: In step S1, the hydrophilic monomer includes one or a combination of acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, vinylpyrrolidone, hydroxyethyl acrylate, hydroxypropyl acrylate, dimethylaminoethyl acrylate, etc.

5. The preparation method of a high-solid-content waterborne polyurethane adhesive according to claim 1, wherein: In step S1, the polyester polyol includes one or a combination of polyethylene adipate glycol, polyethylene phthalate glycol, polycaprolactone glycol, poly(1,6-hexanediol carbonate) glycol, polypropylene glycol, polypropylene oxide triol, tertiary amino polyether tetraol, polytetrahydrofuran glycol, etc.

6. The preparation method of a high-solid-content waterborne polyurethane adhesive according to claim 1, characterized in that: In step S1, the solvent includes one or a combination of acetone, isopropanol, methanol, ethanol, N,N-dimethylformamide, etc.

7. The preparation method of a high-solid-content aqueous polyurethane adhesive according to claim 1, characterized in that: In step S2, heat to 90 - 100 °C by means of an oil bath and heat to 40 - 50 °C by means of a water bath.

8. The preparation method of a high-solid-content aqueous polyurethane adhesive according to claim 1, characterized in that: In step S2, the polyisocyanate includes one or a combination of toluene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, dimethylbiphenyl diisocyanate, 1,6-hexamethylene diisocyanate, tetramethyl-m-xylene diisocyanate, isophorone diisocyanate, methylcyclohexyl diisocyanate, 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, norbornane diisocyanate, etc.

9. The preparation method of a high-solid-content waterborne polyurethane adhesive according to claim 1, characterized in that: In step S2, the catalyst includes one or a combination of triethylenediamine, bis[2-(N,N-dimethylaminoethyl)] ether, 2-(2-dimethylamino-ethoxy)ethanol, N-ethylmorpholine, dibutyltin dilaurate, stannous octoate, etc.

10. A high-solid-content waterborne polyurethane adhesive, characterized in that: Prepared by the preparation method described in any one of claims 1 - 9.