UV and moisture dual-curing polyurethane adhesive and preparation method thereof

Abstract

The invention 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 is prepared from, by weight, 50-70 parts of acrylic acid modified polyether polyol resin and 20-30 parts of crystalline polyester polyol; 10 to 20 parts of a diluent, 0.1 to 0.3 part of a UV initiator and 0.1 to 0.3 part of a moisture curing catalyst; the polyurethane resin further comprises isocyanate, and the isocyanate is added according to the ratio R value of an NCO group to a hydroxyl group being 2.05-2.1. The UV and moisture dual-curing polyurethane adhesive disclosed by the invention has the advantages that 1, the viscosity is moderate, and normal-temperature dispensing can be carried out; 2, the strength can be quickly improved after UV irradiation curing, the bonding strength can reach 2 mpa or above within 5 min, and the bonding force can be well improved; and thirdly, post-curing is carried out through moisture after lamination, and the final bonding strength can reach 10 mpa or above.

Description

Technical Field

[0001] The 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] Ordinary polyurethane hot melt adhesive (PUR) on the market can provide a certain initial bonding strength through the cohesive force generated by the crystalline polymer during the cooling process. It usually requires weight holding or clamping holding, and the holding time generally needs to be more than 2 hours, which can no longer meet the requirements of rapid assembly, seriously affecting production efficiency and increasing production costs. In addition, current PUR generally requires high-temperature dispensing, requires sleeve heating, and the dispensing temperature ranges from 90-120℃, which puts relatively high requirements 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 to be solved. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned prior art, the present invention provides a one-component room temperature dispensing and pressure-free UV moisture dual-curing polyurethane adhesive and a preparation method thereof. The specific technical scheme 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 the purpose of rapid curing and providing initial adhesion strength; the presence of crystalline polyester polyol can be prepared into a prepolymer with isocyanate to provide moisture curing strength and bonding 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 well 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 well play the role of 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, add alkali to neutralize the sulfuric acid, then wash with water until neutral, and remove small molecules by reduced pressure 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 toluene is the same as the total mass of 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 by 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] The 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 1-3h, isocyanate is added, reacted at 80-100°C for 1-3 hours, cooled to 40-60°C, acrylic modified polyether polyol, diluent, UV initiator and moisture curing catalyst are added, vacuum stirred at 50-70°C for 20-60 minutes, and 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 advantages that, first, the viscosity is moderate and dispensing can be performed at room temperature; second, the strength is quickly increased after UV irradiation curing, and the bonding strength can reach more than 2 MPa in 5 minutes, which can greatly improve the bonding force; third, after lamination, post-curing is performed through moisture, and the final bonding strength can reach more than 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] Embodiment 1:

[0031] Preparation of acrylic acid modified polyether polyol:

[0032] 1 mol of raw materials polypropylene oxide (n=10) and 1.2 mol of acrylic acid are added into 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 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 reflux reaction is performed 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 reduced pressure distillation to obtain 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 based on it. 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, discharge the material, and obtain UV moisture dual-curing polyurethane adhesive.

[0035] The UV moisture curing 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 isocyanate ethyl acrylate, 0.1 parts of 2-isopropylthioxanthone, and 0.1 parts of moisture curing catalyst dibutyltin dilaurate.

[0037] Embodiment 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 methods are the same as those in Example 1, which will not be described again 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 curing 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 isocyanate ethyl acrylate, 0.3 parts of UV initiator 2-isopropylthioxanthone, 0.2 parts of moisture curing catalyst dibutyltin dilaurate.

[0043] Embodiment 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 methods 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 curing 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 isocyanate methyl acrylate, 0.1 parts of UV initiator 2-isopropylthioxanthone, 0.3 parts of moisture curing catalyst tetrabutyl titanate.

[0049] Embodiment 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 methods 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 curing 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 3542 PUR structural adhesive.

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

[0058] Adhesive strength test: Use a dispensing machine to dispense the adhesive of Examples 1-4 at room temperature 25°C and the adhesive of Comparative Example 1 at 110°C onto a polycarbonate substrate with a width of about 2 mm. Then, another polycarbonate substrate is attached to the polycarbonate substrate, and the adhesive line is irradiated with a 365nm UV-LED light source with an irradiation 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 the adhesive strength was stretched in the shear direction at a rate of 300 mm / min using a tensile tester 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 has a higher curing bonding strength after 7 days than the commercially available adhesive, especially in terms of bonding strength at 5 minutes and 30 minutes, showing good adhesion, which can well reduce the curing time, and the bonded components are very firm, so as to facilitate entering the next link. The UV moisture-curing polyurethane adhesive prepared by the present invention has the fast curing performance of UV glue and the good moisture and heat resistance 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 principle of the present invention should be included in the protection scope 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): 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, add alkali to neutralize the sulfuric acid, then wash with water until neutral, and remove small molecules by reduced pressure 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 toluene is the same as the total mass of 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 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.

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 by an ester exchange method.

7. The UV moisture dual-curing polyurethane adhesive according to claim 1, characterized in that: The crystalline polyester polyol is preferably 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 UV initiator is one of dibutyltin dilaurate and tetrabutyl titanate.

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

10. A method for preparing the UV moisture dual-curing polyurethane adhesive as claimed in claims 1 to 9, characterized in that: The steps include: The crystalline polyester polyol resin is vacuum dehydrated at 100-140°C for 1-3h, isocyanate is added, reacted at 80-100°C for 1-3 hours, cooled to 40-60°C, acrylic modified polyether polyol, diluent, UV initiator and moisture curing catalyst are added, vacuum stirred at 50-70°C for 20-60 minutes, and discharged to obtain a UV moisture dual-curing polyurethane adhesive.

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