Reactive polyurethane hot melt adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of adhesives, and particularly relates to a reactive polyurethane hot melt adhesive and a preparation method thereof. The reactive polyurethane hot melt adhesive is prepared from the following raw materials in parts by weight: 1 to 50 parts of polyester polyol polymer, 20 to 90 parts of polyether polyol, 1 to 6 parts of polyolefin polyol, 2 to 10 parts of self-made modifier, 2 to 20 parts of isocyanate compound B, 1 to 10 parts of additive, 0.01 to 3 parts of catalyst A and 0.01 to 5 parts of coupling agent. According to the invention, flexible isocyanate reacts with polyol to obtain a self-made modifier, the self-made modifier is matched with polyolefin polyol to be used in the polyurethane hot melt adhesive, and through reasonable formula design, the low-modulus and low-hardness reactive polyurethane adhesive can be prepared on the basis of ensuring the bonding strength of the polyurethane hot melt adhesive.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a reactive polyurethane hot melt adhesive and a preparation method thereof. Background Art

[0002] Reactive polyurethane hot melt adhesive is an environmentally friendly hot melt adhesive. It not only has the easy-to-operate process characteristics of ordinary hot melt adhesive, but also contains active isocyanate groups. It can still undergo curing and cross-linking reactions with moisture in the air at room temperature, thereby obtaining excellent bonding properties, good flexibility and weather resistance, etc. Therefore, it is widely used in various industries such as consumer electronics, woodworking, home appliances, and textiles.

[0003] In view of the material upgrade and development of current electronic products, with the further development of science and technology, the further development of miniaturization and intelligence of electronic products, especially the development of smart wearable and human-computer interactive electronic products, the requirements for glue are becoming more and more diversified, and the miniaturization of devices has further requirements on the modulus and hardness of glue. Summary of the invention

[0004] In view of the above deficiencies in the prior art, the object of the present invention is to provide a reactive polyurethane hot melt adhesive and a preparation method thereof. The reactive polyurethane hot melt adhesive prepared by the method has a lower modulus and hardness.

[0005] One of the purposes of the present invention is to provide a reactive polyurethane hot melt adhesive, comprising the following raw materials in parts by weight: 1 to 50 parts of polyester polyol polymer, 20 to 90 parts of polyether polyol, 1 to 6 parts of polyolefin polyol, 2 to 10 parts of homemade modifier, 2 to 20 parts of isocyanate compound B, 1 to 10 parts of additive, 0.01 to 3 parts of catalyst A, and 0.01 to 5 parts of coupling agent.

[0006] Preferably, the preparation method of the homemade modifier comprises the following steps: adding isocyanate compound A into a container, heating to 65-100°C, adding dehydrated polyol A, heating to 80-120°C, adding catalyst B, reacting under the protection of high-purity nitrogen, and sealing to obtain the homemade modifier, wherein the homemade modifier is terminated with hydroxyl groups, and the ratio of the raw materials is the molar number of hydroxyl groups ≥ the molar number of isocyanate groups × 2.

[0007] Wherein, catalyst B is a catalyst that promotes the reaction of hydroxyl and isocyanate, including but not limited to organic catalysts such as dimethylimidazole, triethylamine or metal catalysts.

[0008] Preferably, the amount of the catalyst B is 0.1% to 5% of the total mass of the isocyanate compound A and the dehydrated polyol A. The type of the polyol A is not limited, and any polyol can be selected according to the formula design, and polypropylene diol is preferred.

[0009] Preferably, the isocyanate compound A is a flexible polyisocyanate compound, more preferably HDI (hexamethylene diisocyanate) and PDI (1,5-pentane diisocyanate) and their derivatives. The cyanate compound B is a polyisocyanate compound with high reactivity, more preferably an aromatic isocyanate, which can be at least one of methylene diphenyl diisocyanate (MDI), liquefied methylene diphenyl diisocyanate (MDI), polymerized methylene diphenyl diisocyanate, toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), and polymethylene polyphenyl isocyanate (PAPI).

[0010] Preferably, the polyester polyol polymer is at least one of a common polyester polyol polymer, a polycaprolactone polyol polymer, a dimer acid polyol polymer and a polycarbonate polyol polymer.

[0011] More preferably, the common polyester polyol polymer is a polymer produced by reacting an acid or anhydride with a corresponding alcohol, and is polymerized by at least one of adipic acid, sebacic acid, dodecanoic acid, isophthalic acid, terephthalic acid, phthalic acid, and phthalic anhydride with at least one of 1,4-butanediol, diethylene glycol, neopentyl glycol, ethylene glycol, cyclohexanediol, diethylene glycol, 1,6-hexanediol, and 3-methyl-1,5-pentanediol; the polycaprolactone polyol is a poly-ε-caprolactone polyol obtained by ring-opening polymerization of ε-caprolactone; the dimer acid polyol polymer is a polyol polymer modified by dimer acid; the polycarbonate polyol polymer is a polyol polymer containing a polycarbonate group, such as polycarbonate 1,6-hexanediol ester polyol, pentanediol, hexanediol, butanediol, propylene glycol, etc. copolymerized polyester, and at least one of polycyclohexane carbonate glycol ester polyol.

[0012] Preferably, the polyether polyol is at least one of a ring-opening polymer of ethylene glycol, propylene glycol, tetrahydrofuran, 3-methyltetrahydrofuran, and a random copolymer or a block copolymer thereof or a derivative thereof.

[0013] Preferably, the polyolefin polyol is at least one of polybutadiene polyol and modified polyols thereof.

[0014] Preferably, the additive is an inert low molecular weight substance, more preferably a petroleum resin or a rosin resin.

[0015] Preferably, the catalyst A is at least one of dibutyltin dilaurate, stannous octoate, dibutylene acetate, triethylenediamine, bismorpholinyl diethyl ether, and N,N-dimethylethanolamine.

[0016] The coupling agent is a conventional coupling agent, preferably at least one of silanes, titanates, aluminates, organic chromium complexes, zirconium compounds, borides, phosphates, stannates and the like.

[0017] A second object of the present invention is to provide a method for preparing the reactive polyurethane hot melt adhesive, comprising the following steps:

[0018] (1) 1-50 parts of polyester polyol polymer, 20-90 parts of polyether polyol, 1-6 parts of polyolefin polyol, 1-10 parts of additives, and 2-10 parts of self-made modifier are heated to 120-140° C. and vacuum dehydrated at 300 r / min for 2 h to 4 h;

[0019] (2) 2 to 20 parts of isocyanate compound B are added and reacted at 80 to 120° C. in a vacuum state for 30 to 120 minutes. Then, 0.01 to 3 parts of catalyst A and 0.01 to 5 parts of coupling agent are added. The mixture is stirred for 30 to 60 minutes in a vacuum state and then discharged and sealed in a vacuum state for storage.

[0020] Compared with the prior art, the invention has the following beneficial effects: the invention obtains a self-made modifier by reacting a flexible isocyanate with a polyol, and the modifier is used as a modified polyol. The introduced flexible isocyanate can reduce the hardness and modulus of the final cured product on the one hand, and retain the urethane bond on the other hand to ensure the final curing strength, and finally terminate with an aromatic isocyanate to improve the curing speed and strength. At the same time, the modifier can also improve the compatibility with polyolefin polyol compounds, and through formula design, a low modulus and low hardness reactive polyurethane adhesive can be prepared. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention and to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention is further described in detail below in conjunction with embodiments.

[0022] Example of preparation of self-made modifier

[0023] Add HDI into a container, heat it to 80°C, add dehydrated polypropylene diol with a molecular weight of 2000, heat it to 100°C, add an organic bismuth catalyst in an amount of 0.2%, react for 2 hours under high-purity nitrogen protection, and seal it to obtain a homemade modifier. The ratio of the raw materials is hydroxyl mole number: isocyanate mole number = 2.1:1.

[0024] Preparation of reactive polyurethane hot melt adhesive:

[0025] (1) 1-50 parts of polyester polyol polymer, 20-90 parts of polyether polyol, 1-6 parts of polyolefin polyol, 1-10 parts of additives, and 2-10 parts of self-made modifier are heated to 120-140° C. and vacuum dehydrated at 300 r / min for 2 h to 4 h;

[0026] (2) 2 to 20 parts of isocyanate compound B are added and reacted at 80 to 120 degrees Celsius in a vacuum state for 30 to 120 minutes. Then, 0.01 to 3 parts of catalyst A and 0.01 to 5 parts of coupling agent are added. The mixture is stirred for 30 to 60 minutes under vacuum conditions and then discharged and sealed in a vacuum state for storage.

[0027] Example 1

[0028] By weight, 18 parts of 3500 molecular weight polyhexane adipate diol, 22 parts of 2000 molecular weight polyneopentyl adipate diol, 5 parts of polybutadiene diol, 6 parts of homemade modifier, 25 parts of 2000 molecular weight polypropylene diol, and 10 parts of petroleum resin are added to a reaction bottle, heated to 130-140°C, and vacuum dehydrated for 2 hours at 300 / min stirring conditions; then, the temperature is lowered to 100°C, 13.7 parts of 4,4'-diphenylmethane diisocyanate (MDI) are added, and after reacting for 1 hour at a stirring speed of 400r / min under vacuum conditions, 0.1 parts of catalyst dimorpholine diethyl ether (DMDEE) and 0.2 parts of γ-mercaptopropyltriethoxysilane are added, stirring is continued for 30 minutes, the material is discharged, and vacuum sealed for storage.

[0029] Example 2

[0030] By weight, 15 parts of 3500 molecular weight polyhexane adipate diol, 29 parts of 2000 molecular weight polyneopentyl adipate diol, 4 parts of polybutadiene diol, 8 parts of homemade modifier, 21 parts of 2000 molecular weight polypropylene diol, and 10 parts of petroleum resin are added to a reaction bottle, heated to 130-140°C, and vacuum dehydrated for 2 hours at 300 / min stirring conditions; then, the temperature is lowered to 100°C, 12.7 parts of 4,4'-diphenylmethane diisocyanate (MDI) are added, and after reacting for 1 hour at a stirring speed of 400r / min under vacuum conditions, 0.1 parts of catalyst (DMDEE) and 0.2 parts of γ-mercaptopropyltriethoxysilane are added, stirring is continued for 30 minutes, the material is discharged, and vacuum sealed for storage.

[0031] Comparative Example 1

[0032] According to the weight percentage, 20 parts of 3500 molecular weight polyhexane adipate diol, 20 parts of 2000 molecular weight polyneopentyl adipate diol, 34 parts of 2000 molecular weight polypropylene diol, and 10 parts of petroleum resin were heated to 120-140°C, added to the reaction bottle, and vacuum dehydrated for 2 hours under the stirring condition of 300 / min. Then, the temperature was lowered to 100°C, 15.7 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added, and after reacting for 1 hour at a stirring speed of 400r / min under vacuum conditions, 0.1 parts of catalyst (DMDEE) and 0.2 parts of γ-mercaptopropyl triethoxysilane were added, and the stirring was continued for 30 minutes before discharging the material and vacuum sealing for storage.

[0033] Comparative Example 2

[0034] According to weight, 20 parts of 3500 molecular weight polyhexane adipate diol, 20 parts of 2000 molecular weight polyneopentyl adipate diol, 30 parts of 2000 molecular weight polypropylene diol, 4 parts of polybutadiene diol, and 10 parts of petroleum resin were heated to 120-140°C, added to the reaction bottle, and vacuum dehydrated for 2 hours under 300 / min stirring conditions. Then, the temperature was lowered to 100°C, 15.7 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added, and after reacting for 1 hour at a stirring speed of 400r / min under vacuum conditions, 0.1 parts of catalyst (DMDEE) and 0.2 parts of γ-mercaptopropyl triethoxysilane were added, and the material was discharged after continuing to stir for 30 minutes, and vacuum sealed for storage.

[0035] Comparative Example 3

[0036] According to weight, 20 parts of 3500 molecular weight polyhexane adipate diol, 20 parts of 2000 molecular weight polyneopentyl adipate diol, 30 parts of 2000 molecular weight polypropylene diol, 4 parts of polybutadiene diol, and 10 parts of petroleum resin were heated to 120-140°C, added to the reaction bottle, and vacuum dehydrated for 2 hours under 300 / min stirring conditions. Then, the temperature was lowered to 100°C, 12.7 parts of 4,4'-diphenylmethane diisocyanate (MDI) and 3 parts of PDI were added, and after reacting for 1 hour at a stirring speed of 400r / min under vacuum conditions, 0.1 parts of catalyst (DMDEE) and 0.2 parts of γ-mercaptopropyl triethoxysilane were added, and the material was discharged after continuing to stir for 30 minutes, and vacuum sealed for storage.

[0037] test

[0038] (1) Adhesive strength test: The hot melt adhesive obtained in the embodiment and the comparative example was dispensed onto a PC substrate at 110°C using a dispensing machine, with the adhesive line width being a closed circle of 1 mm. The PC substrate to be tested was then attached to another PC substrate to be tested. The adhesive strength was tested for 24 hours under curing conditions of 25°C and 50% RH.

[0039] The prepared bond strength evaluation sheet was stretched at a rate of 10 mm / min using a tensile tester to measure the pull-out strength.

[0040] (2) Modulus test: The glue was made into a film with a thickness of about 0.2 mm and cured for 7 days under the conditions of temperature 25° C. and humidity 50% RH. The modulus was tested by DMA.

[0041] The performance test results of the products obtained in Examples 1-2 and Comparative Examples 1-3 are shown in Table 1.

[0042] Table 1. Performance test results of products in Examples 1-2 and Comparative Examples 1-3

[0043]

[0044] From the comparative data, it can be seen that the modulus of the system can be reduced by using polyolefin diol, which has little effect on the strength. The modulus can be further reduced by adding a modifier at the same time. The polyurethane hot melt prepared by the present invention has good compatibility, good bonding performance, low hardness and modulus.

[0045] 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 reactive polyurethane hot melt adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 1 to 50 parts of polyester polyol polymer, 20 to 90 parts of polyether polyol, 1 to 6 parts of polyolefin polyol, 2 to 10 parts of self-made modifier, 2 to 20 parts of isocyanate compound B, 1 to 10 parts of additive, 0.01 to 3 parts of catalyst A and 0.01 to 5 parts of coupling agent.

2. The reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The preparation method of the self-made modifier comprises the following steps: adding an isocyanate compound A into a container, heating it to 65-100° C., adding a dehydrated polyol A, heating it to 80-120° C., adding a catalyst B, reacting under the protection of high-purity nitrogen, and sealing and storing to obtain the self-made modifier, wherein the self-made modifier is terminated with a hydroxyl group.

3. The reactive polyurethane hot melt adhesive according to claim 2, characterized in that: The isocyanate compound A is a flexible polyisocyanate compound, and the cyanate compound B is a polyisocyanate compound with relatively high reaction activity.

4. The reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The polyester polyol polymer is at least one of a common polyester polyol polymer, a polycaprolactone polyol polymer, a dimer acid polyol polymer and a polycarbonate polyol polymer.

5. The reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The polyether polyol is at least one of the ring-opening polymers of ethylene glycol, propylene glycol, tetrahydrofuran, 3-methyltetrahydrofuran, and random copolymers or block copolymers thereof or their derivatives.

6. The reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The polyolefin polyols include polybutadiene polyols and modified polyols thereof.

7. The reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The additive is petroleum resin or rosin resin.

8. The reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The catalyst A is at least one of dibutyltin dilaurate, stannous octoate, dibutylene acetate, triethylenediamine, and bismorpholinyl diethyl ether, and the catalyst B is an organic catalyst or a metal catalyst.

9. A method for preparing the reactive polyurethane hot melt adhesive according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) 1-50 parts of polyester polyol polymer, 20-90 parts of polyether polyol, 1-6 parts of polyolefin polyol, 1-10 parts of additives, and 2-10 parts of self-made modifier are heated to 120-140° C. and vacuum dehydrated at 300 r / min for 2 h to 4 h; (2) 2 to 20 parts of isocyanate compound B are added and reacted at 80 to 120° C. in a vacuum state for 30 to 120 minutes. Then, 0.01 to 3 parts of catalyst A and 0.01 to 5 parts of coupling agent are added. The mixture is stirred for 30 to 60 minutes in a vacuum state and then discharged and sealed in a vacuum state for storage.

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