IR moisture curing polyurethane hot melt adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of polyurethane hot melt adhesives, and particularly relates to an IR moisture curing polyurethane hot melt adhesive and a preparation method thereof. The IR moisture curing polyurethane hot melt adhesive is prepared from the following components in parts by weight: 30 to 80 parts of a polyol polymer B, 10 to 40 parts of an isocyanate compound, 0.1 to 50 parts of modified polyurethane acrylate, 0.01 to 3 parts of a catalyst, 0.01 to 5 parts of up-conversion nano particles, 0.01 to 5 parts of a photoinitiator, 1 to 30 parts of thermoplastic resin and 1 to 12 parts of tackifying resin. The polyurethane hot melt adhesive provided by the invention can be suitable for non-UV light-transmitting and infrared-transmitting plastic materials, and after the product is applied to and attached to an IR light-transmitting material, the purpose of rapid fixation can be achieved by using IR illumination.

Description

Technical Field

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

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

[0003] Because moisture reaction is slow and requires time to reach a certain strength, practical applications usually require pressure holding, special molds, and a specific pressure holding time, which increases costs and affects production efficiency. Therefore, UV (ultraviolet) moisture dual-curing reactive polyurethane hot melt adhesives have begun to be widely studied, with the aim of achieving rapid positioning and improved production efficiency while the cured product possesses the good mechanical properties and aging resistance of reactive polyurethane hot melt adhesives.

[0004] However, in actual use, it has been found that many of the materials being bonded are UV-opaque, making it impossible to achieve the desired effect using ordinary UV-curing and moisture-curing polyurethane hot melt adhesives. Since IR (infrared) light can penetrate some UV-opaque materials, IR curing technology has become another hot topic and has been widely studied. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides an IR moisture-curing polyurethane hot melt adhesive and its preparation method. It is applicable to non-UV transparent but infrared transparent plastic materials. After the product is applied to IR transparent materials and bonded together, it can be quickly fixed by IR light irradiation.

[0006] The specific technical solution is as follows: The first objective of this invention is to provide an IR moisture-curing polyurethane hot melt adhesive, comprising, by weight, the following components: 30-80 parts of polyol polymer B, 10-40 parts of isocyanate compound, 0.1-50 parts of modified polyurethane acrylate, 0.01-3 parts of catalyst, 0.01-5 parts of upconversion nanoparticles, 0.01-5 parts of photoinitiator, 1-30 parts of thermoplastic resin, and 1-12 parts of tackifying resin.

[0007] Furthermore, the preparation method of the modified polyurethane acrylate includes the following steps: 10-80 parts of dehydrated polyol polymer A are heated to 65-100°C, 5-40 parts of isocyanate compound are added, the temperature is raised to 80-100°C, and the reaction is carried out under vacuum for 30-120 minutes. Then, the temperature is lowered to 60-80°C, 0.01-1 parts of polymerization inhibitor are added and stirred thoroughly, 0.1-10 parts of dehydrated hydroxyl-containing acrylate compound are added, the temperature is raised to 85-100°C, and the reaction is carried out under high-purity nitrogen protection for 30-240 minutes. After the reaction is complete, 0.01-1 parts of dehydrating agent are added, and the mixture is sealed and stored to obtain the self-made modified polyurethane acrylate, wherein the polyurethane acrylate has a specific functional structure.

[0008] Furthermore, the polyol polymer A refers to a high molecular weight polyester or polyether polyol with a functionality of 3.

[0009] Furthermore, the isocyanate compound is a polyfunctional isocyanate compound, which refers to an isocyanate compound with a functionality of 2.

[0010] Furthermore, the isocyanate compound is one or a mixture of several of the following: methylene diphenyl diisocyanate (MDI), liquefied methylene diphenyl diisocyanate (liquefied MDI), hydrogenated methylene diphenyl diisocyanate (HMDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), polymerized methylene diphenyl diisocyanate, toluene diisocyanate (TDI), polymethylene polyphenyl diisocyanate, naphthalene diisocyanate (NDI), or polymethylene polyphenyl polyisocyanate (PAPI).

[0011] Furthermore, the polymerization inhibitor is a commonly used polymerization inhibitor for free radical compounds. Specifically, the polymerization inhibitor is one or a mixture of several of hydroquinone monomethyl ether, phenol, p-hydroxyanisole (MEHQ), phenothiazine (PTZ), methylhydroquinone (THQ), and tris(N-nitroso-N-phenylhydroxylamine) aluminum salt.

[0012] Furthermore, the dehydrating agent is a commonly used dehydrating agent. Specifically, the dehydrating agent is one or a mixture of several of the following: oxazolidines, monofunctional isocyanates, monofunctional siloxanes, etc.

[0013] Furthermore, in the preparation process of the modified polyurethane acrylate, the molar ratio of NCO to hydroxyl groups in polyol polymer A is greater than 2:1, more preferably between (2.1~2.2):1; the molar ratio of hydroxyl groups to the remaining NCO in the hydroxyl-containing acrylate compound is slightly greater than 1:3, more preferably between 1:3 and 1:2.5.

[0014] The modified polyurethane acrylate has a structure mainly of Formula 1 and a small amount of Formula 2: .

[0015] Furthermore, the polyol polymer B is one or a mixture of several of polyester polyols, polyether polyols, and other polymers containing hydroxyl functional groups, and the molecular weight of the polyol polymer B is 300 to 8000.

[0016] Furthermore, the polyester polyol includes ordinary polyester polyol, polycaprolactone polyol, and polycarbonate polyol; The common polyester polyol is a polymer produced by reacting an acid or acid anhydride with the corresponding alcohol. It is formed by polymerizing at least one acid selected from adipic acid, sebacic acid, dodecanoic acid, isophthalic acid, terephthalic acid, phthalic acid, and phthalic anhydride with at least one alcohol selected from 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 poly-ε-caprolactone polyol obtained by ring-opening polymerization of ε-caprolactone. The polycarbonate polyol is a polymer containing polycarbonate groups, such as polycarbonate 1,6-hexanediol ester polyol, copolyesters of pentanediol, hexanediol, butanediol, and propylene glycol, and polycyclohexanediol carbonate ester polyol, or one or more of these.

[0017] Furthermore, the polyether polyol includes ring-opening polymers of ethylene glycol, propylene glycol, tetrahydrofuran, and 3-methyltetrahydrofuran, as well as random copolymers or block copolymers of them or their derivatives.

[0018] Furthermore, the thermoplastic resin is a thermoplastic acrylic resin.

[0019] Furthermore, the tackifying resin is one or a mixture of several of terpene resin, rosin resin, and petroleum resin.

[0020] Furthermore, the catalyst is one or a mixture of several of the following: dibutyltin dilaurate, stannous octoate, dibutylene acetate, triethylenediamine, and bismorpholino diethyl ether (DMDEE).

[0021] Furthermore, the photoinitiator is a commonly used initiator for free radical polymerization. Specifically, the photoinitiator is one or a mixture of several of 819, 1173, TPO, TPO-L, 907, and 184.

[0022] A second objective of this invention is to provide a method for preparing the above-mentioned IR moisture-curing polyurethane hot melt adhesive, comprising the following steps by weight: Step 1: Add 30-80 parts of polyol polymer B, 1-30 parts of thermoplastic resin, and 1-12 parts of tackifying resin to a reaction flask, heat to 120-140℃, and vacuum dehydrate for 1-5 hours under stirring at 100-1000 r / min. Step 2: Cool down to 80~100℃, add 10~40 parts of isocyanate compound, heat up to 100~120℃, react under vacuum with a stirring speed of 100~1000r / min for 1~5h, then cool down to 40~100℃, add 0.1~50 parts of self-made modified polyurethane acrylate, 0.01~5 parts of upconversion nanoparticles, 0.01~3 parts of catalyst, and 0.01~5 parts of photoinitiator, stir under vacuum for 10~60min, then discharge the material, vacuum seal and store in the dark.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention synthesizes a modified polyurethane acrylate (self-made modifier) ​​containing a certain degree of difunctionality by selecting appropriate raw materials. The modifier contains some difunctional and monofunctional double bonds, as well as isocyanate compounds with a functionality of ≥2. Due to its high crosslinking density, a polyol with a larger molecular weight is selected, which does not affect its bonding and reliability performance.

[0024] The polyurethane hot melt adhesive of the present invention can undergo a polymerization reaction under IR light when bonding IR-permeable materials, providing a certain initial strength immediately. At the same time, subsequent moisture curing grafts it into the entire PUR (polyurethane) system. Even in areas not exposed to light, it can react in a moisture-curing state, thus providing good strength in areas not exposed to light. Detailed Implementation

[0025] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. The parts mentioned in the specific embodiments are parts by weight.

[0026] Preparation Example A method for preparing modified polyurethane acrylate includes the following steps: By weight, 76 parts of dehydrated polyether polyol 330 were heated to 80°C, 20.8 parts of MDI were added, the temperature was raised to 100°C, and the mixture was reacted under vacuum with a stirring speed of 400 r / min for 1 hour. The temperature was then lowered to 60°C, 0.05 parts of hydroquinone monomethyl ether were added and stirred thoroughly. 3.1 parts of hydroxypropyl acrylate were added, the temperature was raised to 100°C, and the mixture was reacted under high-purity nitrogen protection for 3 hours. After the reaction was complete and the NCO (isocyanate group) content no longer changed, 0.05 parts of JH326 (as a dehydrating agent) were added, the mixture was discharged, sealed and stored to obtain the self-made modified polyurethane acrylate.

[0027] Example 1 A method for preparing an IR moisture-curing polyurethane hot melt adhesive, comprising the following steps by weight: Step 1: Add 24 parts of poly(hexylene adipate) glycol with a molecular weight of 3500, 19 parts of poly(neoprene adipate) glycol with a molecular weight of 2000, 16 parts of polytetrahydrofuran ether glycol with a molecular weight of 2000, 2 parts of acrylic resin, and 3 parts of petroleum resin to a reaction flask, heat to 130°C, and dehydrate under vacuum for 2 hours with stirring at 300 r / min. Step 2: Cool down to 100℃, add 13.9 parts of 4,4'-diphenylmethane diisocyanate (MDI), heat to 110℃, react under vacuum with a stirring speed of 450 r / min for 1 h, then cool down to 60℃, add 20 parts of modified polyurethane acrylate (prepared in the preparation example), 1 part of upconversion nanoparticles (105-50-475 from Hangzhou Fuwo Nanotechnology Co., Ltd.), 0.1 parts of DMDEE, and 1 part of photoinitiator TPO. Stir under vacuum with a stirring speed of 450 r / min for 30 min, then discharge the material, seal it in a vacuum and store it away from light.

[0028] Example 2 A method for preparing an IR moisture-curing polyurethane hot melt adhesive, comprising the following steps by weight: Step 1: Add 21 parts of poly(hexylene adipate) glycol (molecular weight 3500), 19 parts of poly(neoprene adipate) glycol (molecular weight 2000), 20 parts of poly(propylene oxide) glycol (molecular weight 2000), 1.6 parts of acrylic resin, and 2.2 parts of petroleum resin to a reaction flask, heat to 130°C, and dehydrate under vacuum for 2 hours with stirring at 300 r / min. Step 2: Cool down to 100℃, add 13.9 parts of 4,4'-diphenylmethane diisocyanate (MDI), heat to 110℃, react under vacuum with a stirring speed of 450 r / min for 1 h, then cool down to 60℃, add 19 parts of modified polyurethane acrylate (prepared in the preparation example), 1.5 parts of upconversion nanoparticles (105-50-475 from Hangzhou Fuwo Nanotechnology Co., Ltd.), 0.12 parts of DMDEE, and 1.5 parts of photoinitiator 819, stir under vacuum with a stirring speed of 450 r / min for 30 min, then discharge the material, vacuum seal and store in the dark.

[0029] Example 3 A method for preparing an IR moisture-curing polyurethane hot melt adhesive, comprising the following steps by weight: Step 1: Add 18 parts of polyhexamethylene adipate diol with a molecular weight of 3500, 20 parts of polycaprolactone diol with a molecular weight of 2000, 12 parts of polycarbonate diol with a molecular weight of 1000, 1 part of acrylic resin, and 1 part of petroleum resin into a reaction flask, heat to 130°C, and dehydrate under vacuum for 2 hours with stirring at 350 r / min. Step 2: Cool down to 100℃, add 14.9 parts of 4,4'-diphenylmethane diisocyanate (MDI), heat to 110℃, react under vacuum with a stirring speed of 450 r / min for 1 h, then cool down to 60℃, add 30 parts of modified polyurethane acrylate (prepared in the preparation example), 2 parts of upconversion nanoparticles (105-50-475 from Hangzhou Fuwo Nanotechnology Co., Ltd.), 0.1 parts of DMDEE, and 1 part of photoinitiator 907. Stir under vacuum with a stirring speed of 450 r / min for 30 min, then discharge the material and store it in a vacuum-sealed, light-protected container.

[0030] Comparative Example 1 A method for preparing a polyurethane hot melt adhesive, comprising the following steps by weight: Step 1: Add 24 parts of 3500 molecular weight poly(hexylene adipate) glycol, 19 parts of 2000 molecular weight poly(neoprene adipate) glycol, 16 parts of 2000 molecular weight polytetrahydrofuran ether glycol, 2 parts of acrylic resin, and 3 parts of petroleum resin to a reaction flask, heat to 130°C, and dehydrate under vacuum for 2 hours with stirring at 300 r / min. Step 2: Cool down to 100℃, add 13.9 parts of 4,4'-diphenylmethane diisocyanate (MDI), heat up to 110℃, react under vacuum with a stirring speed of 450 r / min for 1 hour, then cool down to 60℃, add 0.1 parts of DMDEE, stir under vacuum with a stirring speed of 450 r / min for 30 minutes, then discharge the material, vacuum seal and store in the dark.

[0031] test: The adhesive strength of the polyurethane hot melt adhesives obtained in each embodiment and comparative example was tested using the following methods: The polyurethane hot melt adhesive obtained in each embodiment and comparative example was applied at 110°C using a dispensing machine to a polycarbonate substrate with a width of approximately 2 mm. Then, another polycarbonate substrate was bonded to the polycarbonate substrate, and the adhesive line was irradiated with a near-infrared (IR) light source. After irradiation, the bond strength was tested at 2 minutes (representing the intensity after irradiation), 30 minutes, and 7 days. The curing conditions were 25°C and 50% RH.

[0032] The bond strength evaluation sample was stretched along the shear direction at a speed of 300 mm / min using a tensile testing machine to determine its shear strength against a polycarbonate substrate.

[0033] The test data for each embodiment and comparative example are shown in Table 1.

[0034] Table 1. Test data for each embodiment and comparative example.

[0035] By comparing the test data in Table 1, it can be seen that the polyurethane hot melt adhesive prepared by the embodiments of the present invention has good bonding performance immediately after IR light irradiation, and also has good final bonding strength without light irradiation.

[0036] 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 within the protection scope of the present invention.

Claims

1. An IR moisture-curing polyurethane hot melt adhesive, characterized in that, By weight, it comprises the following components: 30-80 parts of polyol polymer B, 10-40 parts of isocyanate compound, 0.1-50 parts of modified polyurethane acrylate, 0.01-3 parts of catalyst, 0.01-5 parts of upconversion nanoparticles, 0.01-5 parts of photoinitiator, 1-30 parts of thermoplastic resin, and 1-12 parts of tackifying resin.

2. The IR moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that, The preparation method of the modified polyurethane acrylate includes the following steps: 10-80 parts of dehydrated polyol polymer A are heated to 65-100℃, 5-40 parts of isocyanate compound are added, the temperature is raised to 80-100℃, and the reaction is carried out under vacuum for 30-120 min. Then, the temperature is lowered to 60-80℃, 0.01-1 parts of polymerization inhibitor are added and stirred thoroughly. Then, 0.1-10 parts of dehydrated hydroxyl-containing acrylate compound are added, the temperature is raised to 85-100℃, and the reaction is carried out under high-purity nitrogen protection for 30-240 min. After the reaction is complete, 0.01-1 parts of dehydrating agent are added, and the mixture is sealed and stored to obtain the self-made modified polyurethane acrylate.

3. The IR moisture-curing polyurethane hot melt adhesive according to claim 2, characterized in that, The polyol polymer A refers to a polyester or polyether polyol with a functionality of 3.

4. The IR moisture-curing polyurethane hot melt adhesive according to claim 1 or 2, characterized in that, The isocyanate compound is a polyfunctional isocyanate compound, which refers to an isocyanate compound with a functionality of 2.

5. The IR moisture-curing polyurethane hot melt adhesive according to claim 4, characterized in that, The isocyanate compound is one or a mixture of several of the following: methylene diphenyl diisocyanate, liquefied methylene diphenyl diisocyanate, hydrogenated methylene diphenyl diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, polymerized methylene diphenyl diisocyanate, toluene diisocyanate, polymethylene polyphenyl diisocyanate, naphthalene diisocyanate, or polymethylene polyphenyl polyisocyanate.

6. The IR moisture-curing polyurethane hot melt adhesive according to claim 2, characterized in that, The polymerization inhibitor is one or a mixture of several of hydroquinone monomethyl ether, phenol, p-hydroxyanisole, phenothiazine, methylhydroquinone, and tris(N-nitroso-N-phenylhydroxylamine) aluminum salt.

7. The IR moisture-curing polyurethane hot melt adhesive according to claim 2, characterized in that, The dehydrating agent is one or a mixture of several of the following: oxazolidines, monofunctional isocyanates, and monofunctional siloxanes.

8. The IR moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that, The polyol polymer B is one or a mixture of several of polyester polyols, polyether polyols, and other polymers containing hydroxyl functional groups, and the molecular weight of the polyol polymer B is 300 to 8000.

9. The IR moisture-curing polyurethane hot melt adhesive according to claim 1, characterized in that, The thermoplastic resin is a thermoplastic acrylic resin; the tackifying resin is one or a mixture of several of terpene resin, rosin resin, and petroleum resin; the catalyst is one or a mixture of several of dibutyltin dilaurate, stannous octoate, dibutylene acetate, triethylenediamine, and bismorpholinodiethyl ether; and the photoinitiator is one or a mixture of several of 819, 1173, TPO, TPO-L, 907, and 184.

10. A method for preparing an IR moisture-curing polyurethane hot melt adhesive as described in any one of claims 1 to 9, characterized in that, By weight, the following steps are included: Step 1: Add 30-80 parts of polyol polymer B, 1-30 parts of thermoplastic resin, and 1-12 parts of tackifying resin to a reaction flask, heat to 120-140℃, and vacuum dehydrate for 1-5 hours under stirring at 100-1000 r / min. Step 2: Cool down to 80~100℃, add 10~40 parts of isocyanate compound, heat up to 100~120℃, react under vacuum with a stirring speed of 100~1000r / min for 1~5h, then cool down to 40~100℃, add 0.1~50 parts of self-made modified polyurethane acrylate, 0.01~5 parts of upconversion nanoparticles, 0.01~3 parts of catalyst, and 0.01~5 parts of photoinitiator, stir under vacuum for 10~60min, then discharge the material, vacuum seal and store in the dark.

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