A polyurethane hot melt adhesive, its preparation method and application

Abstract

This invention relates to a polyurethane hot melt adhesive, its preparation method, and its application. The raw materials for preparing the polyurethane hot melt adhesive, by weight, include: 100 parts by weight of polyether diol, 40-100 parts by weight of polyester diol, 10-60 parts by weight of hydroxyl-terminated polybutadiene, 10-50 parts by weight of isocyanate, 100-200 parts by weight of polyolefin, 20-100 parts by weight of tackifying resin, and 1-10 parts by weight of adhesion promoter. The tackifying resin includes any one or a combination of at least two of the following: silane coupling agent modified polyisobutylene, silane coupling agent modified amorphous α-polyolefin, or silane coupling agent modified metallocene-catalyzed vinyl copolymer. The polyurethane hot melt adhesive provided by this invention has high initial tack, low activity, is not prone to clogging equipment, and has good aging resistance. After complete curing, it exhibits excellent adhesion and can be used as a hot melt adhesive for automotive lights.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane technology, specifically relating to a polyurethane hot melt adhesive, its preparation method, and its application. Background Technology

[0002] The bonding and sealing of automotive lights is a crucial part of the automotive lighting manufacturing process. The bonding of automotive lights should ensure that they do not experience problems such as delamination under stress, water or oil seepage, discoloration, or fogging when used in various adverse environments. Traditional automotive light bonding applications typically use ordinary hot melt adhesives and two-component silicone sealants. Ordinary hot melt adhesives have the advantages of fast curing and good initial tack, making them the main adhesive used for traditional automotive light bonding. However, the main component of this type of hot melt adhesive is thermoplastic polyolefin, which is highly sensitive to temperature changes and prone to flowing when heated. It is also very sensitive to water and gasoline penetration, causing problems such as water leakage and fogging during use, and even rendering the entire light unusable. Furthermore, polyolefin hot melt adhesives themselves have insufficient adhesion to polycarbonate materials, one of the structural components of automotive lights, especially polycarbonate that has undergone surface hardening and wear-resistant treatment, which is more prone to delamination and fails to meet users' requirements for bonding strength. While two-component silicone sealants offer some improvement in high and low temperature performance, their poor initial tack means that the components often need to be left immobile for several hours after application, occupying space and extending delivery time. Therefore, the development of new polyurethane hot melt adhesives for automotive lights has always been a research hotspot.

[0003] Reactive polyurethane hot melt adhesive (PUR adhesive) is prepared from a single-component, solvent-free prepolymer with terminal isocyanate groups and appropriate additives. Its main component is a prepolymer with terminal isocyanate groups synthesized from polyester polyol and diisocyanate. After melt application, it cures rapidly and has good initial tack strength. During post-curing, moisture diffuses into the adhesive and reacts with the isocyanate groups of the prepolymer to form urea, biuret, and urethane, causing the linear low-molecular-weight prepolymer to form a cross-linked macromolecular structure. This results in better high-temperature resistance, solvent resistance, and water resistance compared to traditional hot melt adhesives. Similar to ordinary hot melt adhesives, PUR adhesive is melted and applied to automotive headlights using a melt glue machine, and then rapidly cooled and cured to achieve high initial bond strength, allowing for various operations such as movement and assembly of the bonded parts. During storage or transportation, the PUR adhesive continues to react with moisture in the air, further increasing the degree of curing and becoming a high-strength, temperature-resistant, and solvent-resistant adhesive. Because polyurethane hot melt adhesive combines the advantages of traditional hot melt adhesives and two-component silicone adhesives, it can perfectly solve the contradiction between rapid positioning and high-strength bonding in automotive headlight bonding, making it an ideal alternative for automotive headlight bonding adhesives.

[0004] Currently, existing research on the performance of reactive polyurethane hot melt adhesives mainly focuses on improving their heat resistance and adhesion. These raw materials typically contain high levels of polyester polyols and polyether polyols, as well as catalysts. CN108467702A discloses a moisture-curing polyurethane hot melt adhesive for automotive lamps and its preparation method, with a polyester polyol content of 10-45 parts and catalysts selected from dibutyltin dilaurate, stannous octoate, and lead octoate. CN103740316A discloses a moisture-curing polyurethane hot melt adhesive for automotive lamps and its preparation method, with a polyester polyol content as high as 60-85 parts and catalysts selected from dibutyltin dilaurate, stannous octoate, and lead octoate. The high content of polyester polyols and catalysts results in high activity in the hot melt adhesive for automotive lamps, causing it to react rapidly with moisture in the air. This can easily lead to skinning on the pressure plate and blockage in the pipeline during application, affecting production cycle time and increasing production costs.

[0005] High initial tack and low initial tack hot melt adhesives for automotive lighting can effectively reduce skinning in pipelines and pressure plates while ensuring high efficiency in automotive lighting assembly lines, thus reducing pipeline scrapping and downtime caused by pipeline blockage; currently, there are no reports of low-activity, high initial tack hot melt adhesives for automotive lighting. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a polyurethane hot melt adhesive, its preparation method, and its application. The polyurethane hot melt adhesive provided by the present invention has the characteristics of high initial tack and low activity, and at the same time, excellent adhesion after complete curing.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a polyurethane hot melt adhesive, wherein the raw materials for preparing the polyurethane hot melt adhesive, by weight, include: 100 parts by weight of polyether diol, 40-100 parts by weight of polyester diol, 10-60 parts by weight of hydroxyl-terminated polybutadiene, 10-50 parts by weight of isocyanate, 100-200 parts by weight of polyolefin, 20-100 parts by weight of tackifying resin, and 1-10 parts by weight of adhesion promoter; wherein the tackifying resin includes any one or a combination of at least two of silane coupling agent modified polyisobutylene, silane coupling agent modified amorphous α-polyolefin, or silane coupling agent modified metallocene-catalyzed vinyl copolymer.

[0009] The polyurethane hot melt adhesive provided by this invention, through the screening of raw materials, results in a polyurethane hot melt adhesive with high initial tack and low reactivity, while also exhibiting high performance after complete curing. Hydroxyl-terminated polybutadiene improves the adhesion of the polyurethane hot melt adhesive to the substrate; polyolefins reduce water vapor permeability, thereby reducing the reactivity and initial tack of the polyurethane hot melt adhesive; and tackifying resins improve the wettability of the polyurethane hot melt adhesive, thereby enhancing both its initial tack and adhesion after complete curing.

[0010] The polyester diol is 40-100 parts by weight, for example, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight, 100 parts by weight, etc.

[0011] The hydroxyl-terminated polybutadiene is 10-60 parts by weight, for example, it can be 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, etc.

[0012] The isocyanate is 10-50 parts by weight, for example, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, etc.

[0013] The polyolefin is 100-200 parts by weight, for example, it can be 100 parts by weight, 110 parts by weight, 120 parts by weight, 130 parts by weight, 140 parts by weight, 150 parts by weight, 160 parts by weight, 170 parts by weight, 180 parts by weight, 190 parts by weight, 200 parts by weight, etc.

[0014] The tackifying resin is 20-100 parts by weight, for example, it can be 20 parts by weight, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight, 100 parts by weight, etc.

[0015] The adhesive promoter is 1-10 parts by weight, for example, it can be 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, etc.

[0016] In this invention, the silane coupling agent modified polyisobutylene can be purchased, for example, from Kaneka Chemical's EPION series; the silane coupling agent modified amorphous α-polyolefin can be purchased, for example, from Evonik's VESTOPLAST 206; and the silane coupling agent modified metallocene-catalyzed vinyl copolymer can be purchased, for example, from Dow Chemical's Si-link series.

[0017] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0018] As a preferred technical solution, the polyether diol includes polyoxypropylene ether diol.

[0019] Preferably, the hydroxyl value of the polyether diol is 25-150 mgKOH / g, for example, it can be 25 mgKOH / g, 30 mgKOH / g, 40 mgKOH / g, 50 mgKOH / g, 60 mgKOH / g, 70 mgKOH / g, 80 mgKOH / g, 90 mgKOH / g, 100 mgKOH / g, 110 mgKOH / g, 120 mgKOH / g, 130 mgKOH / g, 140 mgKOH / g, 150 mgKOH / g, etc.

[0020] In this invention, the polyether diol can be purchased, for example, from Dongda Chemical's DL2000, DL1000, and DL4000, or from Wanhua Chemical's... C2010D C2020 C2030 C2040D, Dow Chemical's VORANOL 2110TB, VORANOL 2120, VORANOL 3000LM, VORANOL 4240, and VORANOL 222-056.

[0021] Preferably, the hydroxyl value of the polyester diol is 10-120 mgKOH / g, for example, it can be 10 mgKOH / g, 20 mgKOH / g, 30 mgKOH / g, 40 mgKOH / g, 50 mgKOH / g, 60 mgKOH / g, 70 mgKOH / g, 80 mgKOH / g, 90 mgKOH / g, 100 mgKOH / g, 110 mgKOH / g, 120 mgKOH / g, etc., and more preferably 10-60 mgKOH / g.

[0022] Preferably, the melting point of the polyester diol is <70°C, for example, it can be 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, etc.

[0023] Preferably, the polyester diol is obtained by polycondensation of a dicarboxylic acid and / or anhydride with a diol.

[0024] Preferably, the dicarboxylic acid includes any one or a combination of at least two of adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, terephthalic acid, phthalic acid, isophthalic acid, or 1,4-cyclohexanedicarboxylic acid.

[0025] Preferably, the anhydride includes any one or a combination of at least two of phthalic anhydride, adipic anhydride, pimelic anhydride, octanoic anhydride, azelaic anhydride, sebacic anhydride, terephthalic anhydride, phthalic anhydride, isophthalic anhydride, or 1,4-cyclohexanedicarboxylic anhydride.

[0026] Preferably, the diol includes any one or a combination of at least two of 1,4-butanediol, 1,6-hexanediol, ethylene glycol, neopentyl glycol, diethylene glycol, 1,2-propanediol, 2-methylpropanediol, or 2,2,4-trimethyl-1,3pentanediol.

[0027] Preferably, the polyester diol comprises a combination of a first polyester diol and a second polyester diol.

[0028] Preferably, the first polyester diol comprises any one or a combination of at least two of the polyester diols obtained by polycondensation of a first dicarboxylic acid and / or a first acid anhydride with a first diol.

[0029] Preferably, the first dicarboxylic acid includes any one or a combination of at least two of adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, terephthalic acid, phthalic acid, isophthalic acid, or 1,4-cyclohexanedicarboxylic acid.

[0030] Preferably, the first acid anhydride includes phthalic anhydride.

[0031] Preferably, the first diol includes any one or a combination of at least two of 1,4-butanediol, 1,6-hexanediol, ethylene glycol, neopentyl glycol, diethylene glycol, 1,2-propanediol, 2-methylpropanediol, or 2,2,4-trimethyl-1,3pentanediol.

[0032] Preferably, the second polyester diol comprises any one or a combination of at least two of the polyester diols obtained by polycondensation of a second dicarboxylic acid and / or a second acid anhydride with a second diol.

[0033] Preferably, the second dicarboxylic acid includes any one or a combination of at least two of adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, terephthalic acid, phthalic acid, isophthalic acid, or 1,4-cyclohexanedicarboxylic acid.

[0034] Preferably, the second acid anhydride comprises phthalic anhydride.

[0035] Preferably, the second diol comprises 2,2,4-trimethyl-1,3-pentanediol.

[0036] In this invention, the polyester diol can be purchased, for example, from Evonik Dynacoll 7362, Dynacoll 7360, Dynacoll 7363, Dynacoll 7365, Dynacoll 7361, Dynacoll 7381, Dynacoll 7110, Dynacoll 7111, Dynacoll 7130, Dynacoll 7131, Dynacoll 7140, Dynacoll 7150, Dynacoll 7210, Dynacoll 7250, Dynacoll 7230, Dynacoll 7255, Dynacoll 7231, Hooker F-531, F-900, F-970, F-972, F-931, F-932, F-902, F-911, F-5610, F-5630, F-4620, F-4621, F-39030, F-39031, F-37070, F-37033, F-37040, F-4910, F-37030, F-37031, F-37032, FJ-20030, Stepan PH-56, PC-205P-30, PD-56, PC-2072P-30, PC-5000P-30, Huide HDPOL6620.

[0037] Preferably, the number average molecular weight of the hydroxyl-terminated polybutadiene is 1000-5000, for example, it can be 1000, 1200, 1500, 1800, 2000, 2200, 2500, 2800, 3000, 3200, 3500, 3800, 4000, 4200, 4500, 4800, etc.

[0038] Preferably, the hydroxyl-terminated polybutadiene has a hydroxyl value of 20-80 mgKOH / g, for example, 20 mgKOH / g, 25 mgKOH / g, 30 mgKOH / g, 35 mgKOH / g, 40 mgKOH / g, 45 mgKOH / g, 50 mgKOH / g, 55 mgKOH / g, 60 mgKOH / g, 65 mgKOH / g, 70 mgKOH / g, 75 mgKOH / g, 80 mgKOH / g, etc.

[0039] Preferably, the isocyanate includes toluene diisocyanate and / or diphenylmethane diisocyanate.

[0040] Preferably, the ratio of the total molar amount of hydroxyl groups in the polyether diol, polyester diol, and hydroxyl-terminated polybutadiene to the molar amount of isocyanate groups in the isocyanate is 1:(1.5-2), for example, it can be 1:1.5, 1:1.55, 1:1.6, 1:1.65, 1:1.7, 1:1.75, 1:1.8, 1:1.85, 1:1.9, 1:1.95, 1:2, etc.

[0041] Preferably, the polyolefin comprises an α-olefin polymer.

[0042] Preferably, the α-olefin includes any one or a combination of at least two of ethylene, propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-octene, or 4-methyl-1-pentene.

[0043] Preferably, the softening point of the polyolefin is 80-120℃, for example, it can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc.

[0044] Preferably, the polyolefin has a melt viscosity of 2000-30000 mPa·s at 190°C, for example, 2000 mPa·s, 3000 mPa·s, 4000 mPa·s, 5000 mPa·s, 6000 mPa·s, 7000 mPa·s, 8000 mPa·s, 9000 mPa·s, 10000 mPa·s, 15000 mPa·s, 20000 mPa·s, 25000 mPa·s, 30000 mPa·s, etc.

[0045] Preferably, the polyolefin is an amorphous polyolefin.

[0046] In this invention, the polyolefin can be purchased. Exemplarily, the polyolefin can be selected from Huntsman APAO RT 2535, APAO RT 2585, APAO RT 2715, APAO RT 2730, APAO RT 2732, APAO RT2780; Eastman Aerafin 35, Eastman Aerafin 17, Eastman Aerafin 17M, Eastman Aerafin 180; Eastoflex E1003 Amorphous Polyolefin, Eastoflex E1015 Amorphous Polyolefin, Eastman Aerafin 180M Polymer; Evonik VESTOPLAST 703, VESTOPLAST 704, VESTOPLAST 708, VESTOPLAST 750, VESTOPLAST 408, VESTOPLAST 508; and Dow POEAFFINTY GA1900, AFFINTY... Any one or a combination of at least two of the following: GA1950, AFFINTY GA1875, AFFINTY GA8200, AFFINTY GA8407, AFFINTY GA1000R, AFFINTY GA9807, and AFFINTY GA9817.

[0047] Preferably, the softening point of the tackifying resin is 80-120℃, for example, it can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc.

[0048] Preferably, the tackifying resin has a melt viscosity of 3000-10000 mPa·s at 190°C, for example, 3000 mPa·s, 4000 mPa·s, 5000 mPa·s, 6000 mPa·s, 7000 mPa·s, 8000 mPa·s, 9000 mPa·s, 10000 mPa·s, etc.

[0049] Preferably, the adhesive promoter comprises any one or a combination of at least two of bis-(γ-trimethoxysilylpropyl)amine, γ-mercaptopropyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, γ-isocyanate-propyltrimethoxysilane, or N-phenyl-γ-aminopropyltrimethoxysilane.

[0050] Preferably, the raw materials for preparing the polyurethane hot melt adhesive further include 0.1-1.5 parts by weight of antioxidant and 0.1-100 parts by weight of carbon black, by weight.

[0051] The antioxidant is present in amounts of 0.1-1.5 parts by weight, for example, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, etc.

[0052] The carbon black is 0.1-100 parts by weight, for example, it can be 0.1 parts by weight, 0.5 parts by weight, 1 part by weight, 5 parts by weight, 10 parts by weight, 20 parts by weight, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight, 100 parts by weight, etc.; in this invention, carbon black can improve the light resistance of polyurethane hot melt adhesive.

[0053] Preferably, the antioxidant includes aromatic amine antioxidants and / or hindered phenolic antioxidants.

[0054] In this invention, the antioxidant can be purchased. For example, the antioxidant is selected from any one or a combination of at least two of RIANOX 1010, RIANOX 1076, RIANOX 1790, RIANOX 168, RIANOX 626, RIANOX DSTP or RIANOX DLTP.

[0055] Preferably, the pH value of the carbon black is >7.5, for example, it can be 7.6, 7.8, 7.9, 8, 8.1, 8.2, 8.4, 8.6, 8.8, 9, 9.2, 9.5, 10, 10.5, 11, 12, 13, 14, etc.

[0056] Preferably, the specific surface area of ​​the carbon black is >100m². 2 / g, for example, can be 101m 2 / g, 105m 2 / g、110m 2 / g, 120m 2 / g、130m 2 / g, 140m 2 / g, 150m 2 / g、160m 2 / g、170m 2 / g、180m 2 / g、190m 2 / g、200m 2 / g、250m 2 / g、300m 2 / g, 350m 2 / g etc.

[0057] In a second aspect, the present invention provides a method for preparing a polyurethane hot melt adhesive as described in the first aspect, the method comprising:

[0058] The polyurethane hot melt adhesive is obtained by reacting polyether diol, polyester diol, hydroxyl-terminated polybutadiene, isocyanate, polyolefin, tackifying resin and adhesive accelerator.

[0059] Preferably, the preparation method specifically includes:

[0060] The polyether diol, the polyester diol, the hydroxyl-terminated polybutadiene, the polyolefin, and the tackifying resin are mixed, and then the isocyanate is added to carry out the first step reaction; the adhesive accelerator is added to the reaction system to carry out the second step reaction, thereby obtaining the polyurethane hot melt adhesive.

[0061] Preferably, the mixed materials also include antioxidants and carbon black.

[0062] Preferably, the mixing process further includes a vacuum dehydration step.

[0063] Preferably, the vacuum dehydration is carried out at 110-130°C, for example, 110°C, 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, etc.

[0064] Preferably, the vacuum dehydration time is 1-3 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, etc.

[0065] Preferably, the first step reaction is carried out in an inert gas atmosphere.

[0066] Preferably, the temperature of the first step reaction is 80-100℃, for example, it can be 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃, 96℃, 98℃, 100℃, etc.

[0067] Preferably, the reaction time of the first step is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, etc.

[0068] Preferably, the second step reaction is carried out under vacuum conditions.

[0069] Preferably, the temperature of the second step reaction is 90-120℃, for example, it can be 90℃, 92℃, 94℃, 96℃, 98℃, 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, 112℃, 114℃, 116℃, 118℃, 120℃, etc.

[0070] Preferably, the reaction time in the second step is 20-60 min, for example, it can be 20 min, 22 min, 25 min, 30 min, 32 min, 35 min, 40 min, 45 min, 48 min, 50 min, 52 min, 55 min, 58 min, 60 min, etc.

[0071] Thirdly, the present invention provides a polyurethane hot melt adhesive as described in the first aspect for use as a hot melt adhesive for automotive lights.

[0072] Compared with the prior art, the present invention has the following beneficial effects:

[0073] The polyurethane hot melt adhesive provided by this invention has high initial tack, low activity, and is not prone to clogging equipment. It also exhibits good aging resistance and excellent adhesion after complete curing, making it suitable as a hot melt adhesive for automotive lights. The curing speed of the polyurethane hot melt adhesive provided by this invention is 0.2-0.3 mm / 24h, the initial bond strength at 10 min is 0.61-0.76 MPa, and the bond strength after complete curing is 2.1-2.3 MPa. Detailed Implementation

[0074] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0075] The sources of some components in the examples and comparative examples are as follows:

[0076] (1) Polyether diols: Dongda Chemical's DL2000 (hydroxyl value 56mgKOH / g) and DL1000 (hydroxyl value 112mgKOH / g);

[0077] (2) Polyester diols: Evonik Dynacoll 7360 (hydroxyl value 32mgKOH / g, melting point 59℃), Evonik Dynacoll 7361 (hydroxyl value 12.5mgKOH / g, melting point 63℃), Huide HDPOL6620 (hydroxyl value 56mgKOH / g, melting point 60℃);

[0078] (3) Hydroxyl-terminated polybutadiene: Total polyBD r45v, hydroxyl value 35-52mgKOH / g, number average molecular weight 2000-3500;

[0079] (4) Amorphous polyolefins: Evonik VESTOPLAST 408 (softening point 118℃, viscosity at 190℃ 8000±2000mPa.s), Evonik VESTOPLAST 508 (softening point 84℃, viscosity at 190℃ 8000±2000mPa.s);

[0080] (5) Tackifying resin silane coupling agent modified amorphous α-polyolefin: Evonik VESTOPLAST 206 (softening point 98℃, viscosity at 190℃ 5000±1000mPa.s);

[0081] (6) MDI: Covestro Mold 44C;

[0082] (7) Antioxidants: RIANX 1010 and RIANX 1076;

[0083] (8) Carbon black: Orion HIBLACK 30 (pH value 8.5, specific surface area 110m²) 2 / g), Orion PRINTEX 90 (pH 9.0, specific surface area 350m²) 2 / g);

[0084] (9) Adhesion promoter: Evonik MTMO, Dynasylan 1124;

[0085] (10) Acrylic resin: Mitsubishi Chemical BR113, softening point 160℃, Tg 75℃.

[0086] Example 1

[0087] A polyurethane hot melt adhesive, wherein the raw materials for preparing the polyurethane hot melt adhesive include: 100 parts by weight of polyether diol DL2000, 60 parts by weight of polyester diol Dynacoll 7360, 20 parts by weight of hydroxyl-terminated polybutadiene polyBD r45v, 30 parts by weight of MDI, 120 parts by weight of amorphous polyolefin VESTOPLAST 408, 50 parts by weight of VESTOPLAST 206, 0.5 parts by weight of antioxidant RIANOX 10, 10 parts by weight of carbon black HIBLACK 30, and an adhesion promoter. MTMO 2 parts by weight;

[0088] The preparation method of the polyurethane hot melt adhesive includes:

[0089] Polyether diol DL2000, polyester diol Dynacoll 7360, amorphous polyolefin VESTOPLAST408, hydroxyl-terminated polybutadiene polyBD r45v, carbon black HIBLACK 30, antioxidant RIANOX 1010, and VESTOPLAST206 were added to a reaction vessel according to the prescribed amounts. The mixture was heated to 115-120℃ and dehydrated for 2 hours under a vacuum of ≤-0.095MPa until the water content was ≤500ppm. Then, the temperature was lowered to 80℃, and the prescribed amount of MDI was added. The mixture was then heated to 90℃ and reacted for 2 hours. Finally, the prescribed amount of adhesion promoter was added. MTMO was stirred and dispersed under vacuum at 100°C for 1 hour to obtain the polyurethane hot melt adhesive.

[0090] Example 2

[0091] A polyurethane hot melt adhesive, wherein the raw materials for preparing the polyurethane hot melt adhesive include: 100 parts by weight of polyether diol DL2000, 80 parts by weight of polyester diol Dynacoll 7360, 40 parts by weight of hydroxyl-terminated polybutadiene polyBD r45v, 35 parts by weight of MDI, 150 parts by weight of amorphous polyolefin VESTOPLAST 408, 30 parts by weight of VESTOPLAST 206, 101 parts by weight of antioxidant RIANOX 10101, 50 parts by weight of carbon black HIBLACK 30, and an adhesion promoter. MTMO 5 parts by weight;

[0092] The preparation method of the polyurethane hot melt adhesive includes:

[0093] Polyether diol DL2000, polyester diol Dynacoll 7360, amorphous polyolefin VESTOPLAST408, hydroxyl-terminated polybutadiene polyBD r45v, carbon black HIBLACK 30, antioxidant RIANOX 1010, and VESTOPLAST206 were added to a reaction vessel according to the prescribed amounts. The mixture was heated to 120-125℃ and dehydrated under a vacuum of ≤-0.095MPa for 1.5 hours until the water content was ≤500ppm. Then, the mixture was cooled to 90℃, and the prescribed amount of MDI was added. The mixture was then heated to 95℃ and reacted for 1.5 hours. Finally, the prescribed amount of adhesion promoter was added. MTMO was stirred and dispersed under vacuum at 100°C for 30 min to obtain the polyurethane hot melt adhesive.

[0094] Example 3

[0095] A polyurethane hot melt adhesive, wherein the raw materials for preparing the polyurethane hot melt adhesive include: 100 parts by weight of polyether diol DL2000, 45 parts by weight of polyester diol HDPOL6620, 55 parts by weight of hydroxyl-terminated polybutadiene polyBD r45v, 40 parts by weight of MDI, 180 parts by weight of amorphous polyolefin VESTOPLAST 508, 70 parts by weight of VESTOPLAST 206, 1.4 parts by weight of antioxidant RIANOX 1076, 90 parts by weight of carbon black PRINTEX 90, and 48 parts by weight of adhesive accelerator Dynasylan 1124.

[0096] The preparation method of the polyurethane hot melt adhesive includes:

[0097] Polyether diol DL2000, polyester diol HDPOL6620, amorphous polyolefin VESTOPLAST 508, hydroxyl-terminated polybutadiene polyBD r45v, carbon black PRINTEX 90, antioxidant RIANOX 1076, and VESTOPLAST 206 were added to a reaction vessel according to the formulation amount. The mixture was heated to 125-130℃ and dehydrated for 1.5 hours under a vacuum of ≤-0.095MPa until the water content was ≤500ppm. Then, the mixture was cooled to 95℃, and the formulation amount of MDI was added. The mixture was then heated to 100℃ and reacted for 1.5 hours. Finally, the formulation amount of adhesive accelerator Dynasylan 1124 was added, and the mixture was stirred and dispersed under vacuum at 110℃ for 30 minutes to obtain the polyurethane hot melt adhesive.

[0098] Example 4

[0099] A polyurethane hot melt adhesive, wherein the raw materials for preparing the polyurethane hot melt adhesive include: 100 parts by weight of polyether diol DL1000, 145 parts by weight of polyester diol Dynacoll 736, 35 parts by weight of hydroxyl-terminated polybutadiene polyBD r45v, 48 parts by weight of MDI, 140 parts by weight of amorphous polyolefin VESTOPLAST 508, 80 parts by weight of VESTOPLAST 206, 0.7 parts by weight of antioxidant RIANOX 1076, 90 parts by weight of carbon black HIBLACK, and an adhesion promoter. MTMO 4 parts by weight;

[0100] The preparation method of the polyurethane hot melt adhesive includes:

[0101] Polyether diol DL1000, polyester diol Dynacoll 7361, amorphous polyolefin VESTOPLAST508, hydroxyl-terminated polybutadiene polyBD r45v, carbon black HIBLACK 30, antioxidant RIANOX 1076, and VESTOPLAST206 were added to a reaction vessel according to the prescribed amounts. The mixture was heated to 120-125℃ and dehydrated under a vacuum of ≤-0.095MPa for 2 hours until the water content was ≤500ppm. Then, the temperature was lowered to 90℃, and the prescribed amount of MDI was added. The mixture was then heated to 95℃ and reacted for 2 hours. Finally, the prescribed amount of adhesion promoter was added. MTMO was stirred and dispersed under vacuum at 120°C for 30 minutes to obtain the polyurethane hot melt adhesive.

[0102] Comparative Example 1

[0103] A polyurethane hot melt adhesive and its preparation method are disclosed. The only difference between this adhesive and Example 1 is that the amount of polyester diol Dynacoll 7360 used is 20 parts by weight. All other raw materials, process parameters and steps are the same as in Example 1.

[0104] Comparative Example 2

[0105] A polyurethane hot melt adhesive and its preparation method are disclosed. The only difference between this adhesive and Example 1 is that the amount of polyester diol Dynacoll 7360 used is 130 parts by weight. All other raw materials, process parameters and steps are the same as in Example 1.

[0106] Comparative Example 3

[0107] A polyurethane hot melt adhesive and its preparation method are disclosed. The only difference between this adhesive and Example 1 is that VESTOPLAST206 is not used. All other raw materials, process parameters and steps are the same as in Example 1.

[0108] Comparative Example 4

[0109] A polyurethane hot melt adhesive and its preparation method are disclosed. The only difference between this adhesive and Example 1 is that hydroxyl-terminated polybutadiene (polyBD r45v) is not used. All other raw materials, process parameters, and steps are the same as in Example 1.

[0110] Comparative Example 5

[0111] A polyurethane hot melt adhesive and its preparation method are disclosed. The only difference between this adhesive and Example 1 is that the amorphous polyolefin VESTOPLAST 408 is not used. All other raw materials, process parameters and steps are the same as in Example 1.

[0112] Comparative Example 6

[0113] A polyurethane hot melt adhesive and its preparation method are disclosed. The only difference between this adhesive and Example 1 is that VESTOPLAST 206 is replaced with an equal amount of acrylic resin BR113. All other raw materials, process parameters and steps are the same as in Example 1.

[0114] Performance testing

[0115] (1) Curing speed: According to GB / T 32369-2015 Determination of curing degree of sealant, wedge groove method;

[0116] (2) Initial bond strength: Samples were prepared and tested in accordance with GB / T 7124-2008. The initial bond strength of the polyurethane hot melt adhesive was tested. The tensile shear strength of the sample was tested after being placed at 25℃ / 50%RH for 30 minutes. The bonding substrate was PP-T40 / PC.

[0117] (3) Bond strength after complete curing: Samples were prepared and tested according to GB / T 7124-2008. The bond strength of the polyurethane hot melt adhesive after complete curing was tested. The tensile shear strength of the sample was tested after curing at 25℃ / 50%RH for 14 days. The bonding substrate was PP-T40 / PC.

[0118] The polyurethane hot melt adhesives provided in Examples 1-4 and Comparative Examples 1-6 were tested according to the above test methods, and the test results are shown in Table 1:

[0119] Table 1

[0120]

[0121] As can be seen from Table 1, the polyurethane hot melt adhesive provided in the embodiments of the present invention has the characteristics of low activity (slow curing speed), high initial bond strength, and high bond strength after complete curing.

[0122] Compared with Example 1, the initial tack and post-curing bond strength of the polyurethane hot melt adhesive provided in Comparative Example 1 were significantly reduced. The amount of crystalline polyester diol has a significant impact on the initial tack and post-curing bond strength of the polyurethane hot melt adhesive.

[0123] Compared with Example 1, the polyurethane hot melt adhesive provided in Comparative Example 2 showed significantly improved activity (curing speed) and a significant decrease in bond strength after complete curing. This is because the excessive amount of crystalline polyester diol disrupted the compatibility of the system, resulting in a decrease in bond strength after the polyurethane hot melt adhesive was completely cured.

[0124] Compared with Example 1, the polyurethane hot melt adhesive provided in Comparative Example 3 showed significantly improved activity (curing speed) and significantly reduced initial tack and post-curing bond strength. The addition of tackifying resin has an important effect on maintaining the low activity, high initial tack and post-curing bond strength of polyurethane hot melt adhesive.

[0125] Compared with Example 1, the polyurethane hot melt adhesive provided in Comparative Example 4 showed significantly improved activity (curing speed) and significantly reduced bond strength after complete curing. Hydroxyl-terminated polybutadiene has an important influence on maintaining the low activity of polyurethane hot melt adhesive and the bond strength after complete curing.

[0126] Compared with Example 1, the polyurethane hot melt adhesive provided in Comparative Example 5 showed significantly improved activity (curing speed) and significantly reduced initial tack and post-curing bond strength. Polyolefin has an important influence on maintaining the low activity, high initial tack and post-curing bond strength of polyurethane hot melt adhesive.

[0127] Compared with Example 1, the polyurethane hot melt adhesive provided in Comparative Example 6 showed significantly improved activity (curing speed) and a significant decrease in bonding strength after complete curing. The type of tackifying resin has an important influence on maintaining the low activity, high initial tack and bonding strength of the polyurethane hot melt adhesive after complete curing.

[0128] The applicant declares that this invention illustrates the polyurethane hot melt adhesive, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A polyurethane hot melt adhesive, characterized in that, The raw materials for preparing the polyurethane hot melt adhesive, by weight, include: 100 parts by weight of polyether diol, 40-100 parts by weight of polyester diol, 10-60 parts by weight of hydroxyl-terminated polybutadiene, 10-50 parts by weight of isocyanate, 100-200 parts by weight of polyolefin, 20-100 parts by weight of tackifying resin, and 1-10 parts by weight of adhesion promoter. The tackifying resin is a silane coupling agent modified amorphous α-polyolefin; The hydroxyl-terminated polybutadiene has a number-average molecular weight of 1000-5000 and a hydroxyl value of 20-80 mgKOH / g. The softening point of the tackifying resin is 80-120℃; the melt viscosity of the tackifying resin at 190℃ is 3000-10000 mPa·s.

2. The polyurethane hot melt adhesive according to claim 1, characterized in that, The polyether diol includes polyoxypropylene ether diol.

3. The polyurethane hot melt adhesive according to claim 1, characterized in that, The hydroxyl value of the polyether diol is 25-150 mg KOH / g.

4. The polyurethane hot melt adhesive according to claim 1, characterized in that, The hydroxyl value of the polyester diol is 10-120 mg KOH / g.

5. The polyurethane hot melt adhesive according to claim 1, characterized in that, The melting point of the polyester diol is <70°C.

6. The polyurethane hot melt adhesive according to claim 1, characterized in that, The polyester diol is obtained by polycondensation of a dicarboxylic acid and / or anhydride with a diol.

7. The polyurethane hot melt adhesive according to claim 6, characterized in that, The dicarboxylic acid includes any one or a combination of at least two of adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, terephthalic acid, phthalic acid, isophthalic acid, or 1,4-cyclohexanedicarboxylic acid.

8. The polyurethane hot melt adhesive according to claim 6, characterized in that, The anhydride includes any one or a combination of at least two of the following: adipic anhydride, pimelic anhydride, octanoic anhydride, azelaic anhydride, sebacic anhydride, terephthalic anhydride, phthalic anhydride, isophthalic anhydride, or 1,4-cyclohexanedicarboxylic anhydride.

9. The polyurethane hot melt adhesive according to claim 6, characterized in that, The diols include any one or a combination of at least two of 1,4-butanediol, 1,6-hexanediol, ethylene glycol, neopentyl glycol, diethylene glycol, 1,2-propanediol, 2-methylpropanediol, or 2,2,4-trimethyl-1,3pentanediol.

10. The polyurethane hot melt adhesive according to claim 1, characterized in that, The isocyanate includes toluene diisocyanate and / or diphenylmethane diisocyanate.

11. The polyurethane hot melt adhesive according to claim 1, characterized in that, The ratio of the total molar amount of hydroxyl groups in the polyether diol, polyester diol, and hydroxyl-terminated polybutadiene to the molar amount of isocyanate groups in the isocyanate is 1:(1.5-2).

12. The polyurethane hot melt adhesive according to claim 1, characterized in that, The polyolefin includes α-olefin polymers.

13. The polyurethane hot melt adhesive according to claim 12, characterized in that, The α-olefin includes any one or a combination of at least two of ethylene, propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-octene, or 4-methyl-1-pentene.

14. The polyurethane hot melt adhesive according to claim 1, characterized in that, The softening point of the polyolefin is 80-120℃.

15. The polyurethane hot melt adhesive according to claim 1, characterized in that, The polyolefin has a melt viscosity of 2000-30000 mPa·s at 190°C.

16. The polyurethane hot melt adhesive according to claim 1, characterized in that, The adhesive promoter includes any one or a combination of at least two of bis-(γ-trimethoxysilylpropyl)amine, γ-mercaptopropyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, γ-isocyanate-propyltrimethoxysilane, or N-phenyl-γ-aminopropyltrimethoxysilane.

17. The polyurethane hot melt adhesive according to claim 1, characterized in that, The raw materials for preparing the polyurethane hot melt adhesive also include 0.1-1.5 parts by weight of antioxidant and 0.1-100 parts by weight of carbon black, by weight.

18. The polyurethane hot melt adhesive according to claim 17, characterized in that, The carbon black has a pH value >7.

5.

19. The polyurethane hot melt adhesive according to claim 17, characterized in that, The specific surface area of ​​the carbon black is >100m². 2 / g.

20. A method for preparing a polyurethane hot melt adhesive as described in any one of claims 1-19, characterized in that, The preparation method includes: The polyurethane hot melt adhesive is obtained by reacting polyether diol, polyester diol, hydroxyl-terminated polybutadiene, isocyanate, polyolefin, tackifying resin and adhesive accelerator.

21. The preparation method according to claim 20, characterized in that, The preparation method specifically includes: The polyether diol, the polyester diol, the hydroxyl-terminated polybutadiene, the polyolefin, and the tackifying resin are mixed, and then the isocyanate is added to carry out the first step reaction; the adhesive accelerator is added to the reaction system to carry out the second step reaction, thereby obtaining the polyurethane hot melt adhesive.

22. The preparation method according to claim 21, characterized in that, The mixture also includes antioxidants and carbon black.

23. The preparation method according to claim 21, characterized in that, The mixing process also includes a vacuum dehydration step.

24. The preparation method according to claim 23, characterized in that, The vacuum dehydration is carried out at 110-130°C.

25. The preparation method according to claim 23, characterized in that, The vacuum dehydration time is 1-3 hours.

26. The preparation method according to claim 21, characterized in that, The first step reaction is carried out in an inert gas atmosphere.

27. The preparation method according to claim 21, characterized in that, The temperature of the first step reaction is 80-100℃.

28. The preparation method according to claim 21, characterized in that, The reaction time for the first step is 1-3 hours.

29. The preparation method according to claim 21, characterized in that, The second step reaction is carried out under vacuum conditions.

30. The preparation method according to claim 21, characterized in that, The temperature for the second step reaction is 90-120℃.

31. The preparation method according to claim 21, characterized in that, The reaction time for the second step is 20-60 minutes.

32. The application of a polyurethane hot melt adhesive as described in any one of claims 1-19 in hot melt adhesives for automotive lights.

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