A uv moisture dual-curing polyurethane adhesive and a preparation method thereof

Abstract

The application belongs to the technical field of adhesives, and relates to a UV and moisture dual-curing polyurethane adhesive and a preparation method thereof.The UV and moisture dual-curing polyurethane adhesive comprises the following components in parts by weight: 50-70 parts of acrylic modified polyether polyol resin, 20-30 parts of crystalline polyester polyol;10-20 parts of diluent, 0.1-0.3 parts of UV initiator, and 0.1-0.3 parts of moisture curing catalyst;and further comprises isocyanate, and the isocyanate is added in a ratio R of NCO groups to hydroxyl groups of 2.05-2.1.The UV and moisture dual-curing polyurethane adhesive has the following advantages: 1, moderate viscosity, normal temperature dispensing can be carried out;2, rapid strength after UV irradiation and curing, the bonding strength can reach more than 2 MPa after 5 min, and the bonding force can be improved;3, after bonding, the final bonding strength can reach more than 10 MPa through moisture after-curing.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and in particular relates to a UV-moisture dual-curing polyurethane adhesive and a preparation method thereof. Background Art

[0002] Commercially available polyurethane hot-melt adhesives (PUR) provide a certain initial bond strength through the cohesive force generated by the crystalline polymer during the cooling process. However, these adhesives typically require weight-holding or clamping for a period of more than two hours, which is insufficient for rapid assembly, significantly impacting production efficiency and increasing costs. Furthermore, current PUR dispensing generally requires high-temperature dispensing, requiring sleeve heating at temperatures ranging from 90-120°C, placing high demands on dispensing equipment.

[0003] In summary, how to provide a polyurethane adhesive that can be dispensed at room temperature, cures quickly, and has extremely high initial bonding strength is an urgent problem that needs to be solved. Summary of the Invention

[0004] In view of the shortcomings of the above-mentioned prior art, the present invention provides a one-component room temperature dispensing, pressure-free, UV-moisture dual-curing polyurethane adhesive and a preparation method thereof. The specific technical solution is as follows:

[0005] The first object of the present invention is to provide a UV moisture dual-curing polyurethane adhesive comprising the following components in parts by weight:

[0006] 50-70 parts of acrylic modified polyether polyol, 20-30 parts of crystalline polyester polyol; 10-20 parts of diluent, 0.1-0.3 parts of UV initiator, 0.1-0.3 parts of moisture curing catalyst;

[0007] Also included isocyanate, the isocyanate is added with a ratio R value of NCO groups to hydroxyl groups of 2.05-2.1;

[0008] The structure of the acrylic acid modified polyether polyol is shown in formula (1):

[0009]

[0010] Where n = 10-50;

[0011] The diluent is one or both of ethyl isocyanate acrylate and methyl isocyanate acrylate.

[0012] The UV-moisture dual-curing polyurethane adhesive of the present invention uses acrylic modified polyether polyol as the main resin and utilizes the UV curing performance of vinyl to achieve rapid curing and provide initial adhesion strength. The presence of crystalline polyester polyol can be prepared into a prepolymer with isocyanate to provide moisture-curing strength and adhesion performance. The presence of isocyanate ethyl acrylate and / or isocyanate methyl acrylate can play a bridging role, providing a UV-curing functional group at one end and a moisture-curing functional group at the other end, which can greatly improve the compatibility and cohesion of the polymer and enhance the creep performance of the glue. At the same time, because it is a small molecule compound with low viscosity, it can effectively act as a diluent and realize the function of dispensing at room temperature.

[0013] Furthermore, the preparation method of the acrylic acid modified polyether polyol is as follows:

[0014] Add concentrated sulfuric acid and toluene as catalysts to polypropylene oxide and acrylic acid, heat to 100-140°C, reflux for 4-6 hours, then add alkali to neutralize the sulfuric acid, then wash with water until neutral, and remove small molecules by vacuum distillation to obtain acrylic acid-modified polyether polyol.

[0015] The reaction equation is:

[0016]

[0017] Where n=10-50.

[0018] Furthermore, the molar ratio of polypropylene oxide to acrylic acid is 1:(1.1-1.2), the amount of the catalyst concentrated sulfuric acid is 1%-5% of the total mass of acrylic acid and polypropylene oxide, and the mass of the toluene is the same as the total mass of the acrylic acid and polypropylene oxide.

[0019] Furthermore, the isocyanate is diphenylmethane-4,4'-diisocyanate (MDI).

[0020] Furthermore, the crystalline polyester polyol is prepared by condensing a dicarboxylic acid and a diol, wherein the dicarboxylic acid is one or more of dodecanedioic acid, terephthalic acid, and isophthalic acid; and the diol is one or more of 1,4-butanediol, 1,6-ethylene glycol, 1,8-octanediol, and 1,10-decanediol.

[0021] Furthermore, the crystalline polyester polyol is polymerized from a dibasic acid and a small molecule polyol through an ester exchange method.

[0022] Furthermore, the crystalline polyester polyol is preferably one or more of Evonik 7360, 7380, and 7382.

[0023] Furthermore, the UV initiator is 2-isopropylthioxanthone.

[0024] Furthermore, the moisture curing catalyst is one of dibutyltin dilaurate and tetrabutyl titanate.

[0025] A second object of the present invention is to provide a method for preparing the above-mentioned UV moisture dual-curing polyurethane adhesive, comprising the following steps:

[0026] The crystalline polyester polyol resin is vacuum dehydrated at 100-140°C for 1-3 hours, isocyanate is added, and the reaction is carried out at 80-100°C for 1-3 hours. The temperature is lowered to 40-60°C, and acrylic modified polyether polyol, diluent, UV initiator and moisture curing catalyst are added. The mixture is vacuum stirred at 50-70°C for 20-60 minutes, and the material is discharged to obtain a UV moisture dual-curing polyurethane adhesive.

[0027] The beneficial effects of the present invention are:

[0028] The UV-moisture dual-curing polyurethane adhesive provided by the present invention has the following advantages: 1. moderate viscosity, which allows for room-temperature dispensing; 2. rapid strength development after UV irradiation curing, with a bonding strength of over 2 MPa in 5 minutes, which can significantly improve bonding strength; 3. moisture post-curing after lamination, with a final bonding strength of over 10 MPa. DETAILED DESCRIPTION

[0029] The principles and features of the present invention are described below in conjunction with embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0030] Example 1:

[0031] Preparation of acrylic acid modified polyether polyol:

[0032] 1 mol of polypropylene oxide (n=10) and 1.2 mol of acrylic acid as raw materials are added to a three-necked flask, and concentrated sulfuric acid and toluene as catalysts are added, wherein the amount of the concentrated sulfuric acid as catalyst is 3% of the total mass of the acrylic acid and polypropylene oxide, and the mass of the toluene is the same as the total mass of the acrylic acid and polypropylene oxide. The temperature is raised to 120° C. and refluxed for 5 hours. Subsequently, KOH is added to neutralize the sulfuric acid, and the mixture is washed with water until neutral. Small molecules are removed by distillation under reduced pressure to obtain an acrylic acid-modified polyether polyol (Structural Formula 1, n=10).

[0033] Preparation method of UV moisture curing polyurethane adhesive:

[0034] Take crystalline polyester polyol resin, vacuum dehydrate it at high temperature of 120℃ for two hours, set the R value between 2.05-2.1, and calculate the amount of MDI. Add MDI, react at 90℃ for 2 hours, cool to 50℃, add acrylic modified polyether polyol, diluent, UV initiator and moisture curing catalyst, stir in vacuum at 60℃ for half an hour, and discharge to obtain UV moisture dual-curing polyurethane adhesive.

[0035] The UV moisture-curable polyurethane adhesive of this embodiment includes the following components in parts by weight:

[0036] 70 parts of acrylic acid-modified polyether polyol (structural formula 1, n=10), 20 parts of crystalline polyester polyol Evonik 7360; 10 parts of diluent ethyl isocyanate acrylate, 0.1 parts of 2-isopropylthioxanthone, and 0.1 parts of moisture curing catalyst dibutyltin dilaurate.

[0037] Example 2:

[0038] Preparation of acrylic acid modified polyether polyol:

[0039] The polypropylene oxide in the raw material is polypropylene oxide with n=20, and the amounts of other substances and the preparation method are the same as those in Example 1, which will not be repeated here.

[0040] The preparation method of the UV moisture-curing polyurethane adhesive is the same as that in Example 1 and will not be repeated here.

[0041] The UV moisture-curable polyurethane adhesive of this embodiment includes the following components in parts by weight:

[0042] 50 parts of acrylic acid-modified polyether polyol (structural formula 1, n=20), 30 parts of crystalline polyester polyol Evonik 7380; 20 parts of diluent ethyl isocyanate acrylate, 0.3 parts of UV initiator 2-isopropylthioxanthone, and 0.2 parts of moisture curing catalyst dibutyltin dilaurate.

[0043] Example 3:

[0044] Preparation of acrylic acid modified polyether polyol:

[0045] The polypropylene oxide in the raw material is polypropylene oxide with n=30, and the amounts of other substances and the preparation method are the same as those in Example 1, which will not be repeated here.

[0046] The preparation method of the UV moisture-curing polyurethane adhesive is the same as that in Example 1 and will not be repeated here.

[0047] The UV moisture-curable polyurethane adhesive of this embodiment includes the following components in parts by weight:

[0048] 55 parts of acrylic modified polyether polyol (structural formula 1, n=30), 25 parts of crystalline polyester polyol Evonik 7382; 20 parts of diluent methyl isocyanate acrylate, 0.1 parts of UV initiator 2-isopropylthioxanthone, 0.3 parts of moisture curing catalyst tetrabutyl titanate.

[0049] Example 4:

[0050] Preparation of acrylic acid modified polyether polyol:

[0051] The polypropylene oxide in the raw material is polypropylene oxide with n=50, and the amounts of other substances and the preparation method are the same as those in Example 1, which will not be repeated here.

[0052] The preparation method of the UV moisture-curing polyurethane adhesive is the same as that in Example 1 and will not be repeated here.

[0053] The UV moisture-curable polyurethane adhesive of this embodiment includes the following components in parts by weight:

[0054] 50 parts of acrylic modified polyether polyol (structural formula 1, n=50), 30 parts of crystalline polyester polyol Evonik 7380; 10 parts of diluent methyl isocyanate acrylate, 10 parts of diluent ethyl isocyanate acrylate, 0.3 parts of UV initiator 2-isopropylthioxanthone, 0.15 parts of moisture curing catalyst tetrabutyl titanate.

[0055] Comparative Example 1:

[0056] Commercially available Henkel Loctite 3542PUR structural adhesive.

[0057] The adhesives of Examples 1-4 and Comparative Example 1 were subjected to performance tests, and the test results are shown in Table 1.

[0058] Adhesive Strength Test: Using a dispensing machine, adhesives from Examples 1-4 were dispensed at room temperature (25°C) and the adhesive from Comparative Example 1 was dispensed at 110°C onto a polycarbonate substrate with a width of approximately 2 mm. Another polycarbonate substrate was then attached to the polycarbonate substrate and the adhesive line was irradiated with a 365nm UV-LED light source at an energy of 3000mJ / cm 2 After the irradiation, the bonding strength was tested 2 minutes (representing the strength after light irradiation), 30 minutes, and 7 days after dispensing. The moisture curing conditions were temperature 25°C and humidity 50% RH.

[0059] The prepared sample for evaluating adhesive strength was stretched in the shear direction at a rate of 300 mm / min using a tensile testing machine to measure the shear strength with respect to the polycarbonate substrate.

[0060] Table 1 Performance test results of Examples 1-4 and Comparative Example 1

[0061]

[0062] The data in Table 1 show that the UV moisture-curing polyurethane adhesive prepared by the present invention exhibits higher bond strength after 7 days of curing than commercially available adhesives, particularly in terms of bond strength at 5 and 30 minutes. This demonstrates excellent adhesion, significantly reducing curing time and ensuring a secure bond between bonded components, facilitating transition to the next step. The UV moisture-curing polyurethane adhesive prepared by the present invention combines the rapid curing properties of UV adhesives with the excellent moisture, heat, and creep resistance of silicone.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A UV moisture dual-curing polyurethane adhesive, characterized in that: The composition comprises the following components in parts by weight: 50-70 parts of acrylic modified polyether polyol, 20-30 parts of crystalline polyester polyol; 10-20 parts of diluent, 0.1-0.3 parts of UV initiator, 0.1-0.3 parts of moisture curing catalyst; Also included isocyanate, the isocyanate is added with a ratio R value of NCO groups to hydroxyl groups of 2.05-2.1; The structure of the acrylic acid modified polyether polyol is shown in formula (1): Formula (1) Where n=10-50; The diluent is one or both of ethyl isocyanate acrylate and methyl isocyanate acrylate.

2. The UV moisture dual-curing polyurethane adhesive according to claim 1, characterized in that The preparation method of the acrylic acid modified polyether polyol is as follows: Add concentrated sulfuric acid and toluene as catalysts to polypropylene oxide and acrylic acid, heat to 100-140°C, reflux for 4-6 hours, then add alkali to neutralize the sulfuric acid, then wash with water until neutral, and remove small molecules by vacuum distillation to obtain acrylic acid-modified polyether polyol.

3. The UV moisture dual-curing polyurethane adhesive according to claim 2, characterized in that The molar ratio of polypropylene oxide to acrylic acid is 1:(1.1-1.2), the amount of the catalyst concentrated sulfuric acid is 1%-5% of the total mass of acrylic acid and polypropylene oxide, and the mass of the toluene is the same as the total mass of the acrylic acid and polypropylene oxide.

4. The UV moisture dual-curing polyurethane adhesive according to claim 1, characterized in that The isocyanate is diphenylmethane-4,4'-diisocyanate.

5. The UV moisture dual-curing polyurethane adhesive according to claim 1, characterized in that The crystalline polyester polyol is prepared by condensing dicarboxylic acid and diol, wherein the dicarboxylic acid is one or more of dodecanedioic acid, terephthalic acid, and isophthalic acid; and the diol is one or more of 1,4-butanediol, 1,6-ethylene glycol, 1,8-octanediol, and 1,10-decanediol.

6. The UV moisture dual-curing polyurethane adhesive according to claim 1, characterized in that The crystalline polyester polyol is polymerized from a dibasic acid and a small molecule polyol through an ester exchange method.

7. The UV moisture dual-curing polyurethane adhesive according to claim 1, characterized in that The crystalline polyester polyol is one or more of Evonik 7360, 7380, and 7382.

8. The UV moisture dual-curing polyurethane adhesive according to claim 1, characterized in that The moisture curing catalyst is one of dibutyltin dilaurate and tetrabutyl titanate.

9. The UV moisture dual-curing polyurethane adhesive according to claim 1, characterized in that The UV initiator is 2-isopropylthioxanthone.

10. A method for preparing the UV moisture dual-curing polyurethane adhesive according to any one of claims 1 to 9, characterized in that: The steps include: The crystalline polyester polyol resin is vacuum dehydrated at 100-140°C for 1-3 hours, isocyanate is added, and the reaction is carried out at 80-100°C for 1-3 hours. The temperature is lowered to 40-60°C, and acrylic modified polyether polyol, diluent, UV initiator and moisture curing catalyst are added. The mixture is vacuum stirred at 50-70°C for 20-60 minutes, and the material is discharged to obtain a UV moisture dual-curing polyurethane adhesive.

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