Low-odor high-heat-creep waterborne polyurethane hot melt adhesive and preparation method thereof

Abstract

The application discloses a low-odor high-heat-creep water-based polyurethane hot melt adhesive and a preparation method thereof, and belongs to the field of water-based polyurethane hot melt adhesives. The hot melt adhesive is prepared from the following raw materials in parts by weight and comprises the following components: 145-175 parts of polyester polyol, 2-8 parts of polyether polyol, 7-9 parts of isocyanate, 1-3 parts of multifunctional isocyanate, 8-10 parts of sulfonic acid type isocyanate, 1-2 parts of sulfonic acid type hydrophilic chain extender, 0.4-1.7 parts of alcohol chain extender, 0.02-0.06 parts of catalyst, 150-270 parts of acetone, 150-270 parts of deionized water, 0.3-1 part of silane coupling agent, 0.2-0.9 parts of thickening agent and 0.2-0.9 parts of defoaming agent. The water-based polyurethane hot melt adhesive is not only environment-friendly, non-toxic and low-odor, but also significantly improves the heat-creep resistance.

Description

Technical Field

[0001] This invention relates to the field of hot melt adhesives, and more particularly to a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive and its preparation method. Background Technology

[0002] Currently, commonly used hot melt adhesives in the automotive, high-speed rail, furniture, shoemaking, and textile industries are divided into oil-based and water-based hot melt adhesives. Oil-based hot melt adhesives have a strong odor and are not environmentally friendly, not only affecting workers' health but also causing the glued parts to continuously emit toxic and harmful substances, impacting the health of users. Water-based polyurethane hot melt adhesives have outstanding environmental protection and bonding performance, and are also one of the important types of water-based hot melt adhesives, enjoying widespread application.

[0003] In existing technologies, some raw materials used in the synthesis of waterborne polyurethane hot melt adhesives, such as triethylamine and diethylamine, can release odors during storage or under heating conditions. Furthermore, if the synthesized waterborne polyurethane hot melt adhesive lacks an internal cross-linking structure, it will have weak heat creep resistance, causing the bonded substrates to spring back, slip, or detach under high temperatures or heating conditions, resulting in the scrapping of the bonded parts and significant economic losses.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] This invention provides a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive and its preparation method. It is not only environmentally friendly, non-toxic, and low-odor, but also significantly improves heat creep resistance, preventing problems such as springing, slippage, and detachment of the bonded substrate in high-temperature weather or under heating conditions, thus avoiding the scrapping of the bonded parts and significant economic losses. This invention offers better economic benefits and can be widely applied in the automotive, high-speed rail, furniture, shoemaking, and textile industries, thereby solving the aforementioned technical problems existing in the prior art.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive, made from the following raw materials in parts by weight:

[0008]

[0009]

[0010] Preferably, in the above-mentioned hot melt adhesive, the number average molecular weight of the polyester polyol is 1000-3000; the polyester polyol is at least one of polybutylene adipate, polypropylene carbonate diol, and polyhexyl sebacate.

[0011] The number average molecular weight of the polyether polyol is 1000-2000; the polyether polyol is at least one of polytetrahydrofuran diol and polypropylene oxide diol.

[0012] The isocyanate is at least one of isoflavone diisocyanate, hexamethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0013] Preferably, in the above-mentioned hot melt adhesive, the polyfunctional isocyanate is at least one of triphenylmethane triisocyanate and HDI trimer.

[0014] Preferably, in the above hot melt adhesive, the sulfonic acid isocyanate is at least one of BY-3508 and BY-3509 from Baiyuan Chemical.

[0015] The sulfonic acid-type hydrophilic chain extender is at least one of BY3305 and BY-3306 from Baiyuan Chemical.

[0016] Preferably, in the above-mentioned hot melt adhesive, the alcohol chain extender is at least one selected from 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, and 1,2-propanediol.

[0017] Preferably, in the above-mentioned hot melt adhesive, the catalyst is at least one of organotin catalysts, stannous octoate catalysts, and organobismuth catalysts.

[0018] Preferably, in the above-mentioned hot melt adhesive, the silane coupling agent is at least one of primary amino, secondary amino silane, and mercaptosilane.

[0019] Preferably, in the above-mentioned hot melt adhesive, the thickener is one or more of Evonik's TEGO Visco Plus 3000, Rohm and Haas's Acrysol RM8W, Acrysol RM5000, and Hefei Anke's HEUR-A and HEUR-B.

[0020] Preferably, in the above-mentioned hot melt adhesive, the defoamer is one or more of BASF Foamaster 8034, BYK018 and BYK019, KLAIN A200 and AFCONA 2590, and Sangjing Chemical SKC DF942 and DF677.

[0021] A method for preparing the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive of the present invention includes the following steps:

[0022] Step 1: According to the formulation of the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive of the present invention, weigh out the following ingredients: polyester polyol, polyether polyol, polyfunctional isocyanate, sulfonic acid isocyanate, sulfonic acid hydrophilic chain extender, alcohol chain extender, catalyst, silane coupling agent, acetone, deionized water, thickener and defoamer.

[0023] Step 2: The polyester polyol, polyether polyol, and sulfonic acid hydrophilic chain extender are added to the reaction apparatus. Dehydration is carried out for 40-60 minutes at 60-100°C and a vacuum of -0.08-0.09 MPa, followed by dehydration for 20-40 minutes at 100-110°C and a vacuum of -0.1 MPa. The temperature is then lowered to 50-60°C, and the isocyanate, polyfunctional isocyanate, sulfonic acid isocyanate, alcohol chain extender, and catalyst are added to the reaction apparatus. The reaction is carried out at 65-80°C for 1-3 hours until the -NCO content reaches 0.9%-1.3%, thus obtaining the first intermediate.

[0024] Step 3: Cool the first intermediate to 35-60°C, then add acetone to the first intermediate to adjust its viscosity, and then add deionized water to emulsify it to obtain the second intermediate.

[0025] Step 4: Control the temperature of the second intermediate at 35-55°C, then add the silane coupling agent to the second intermediate, stir for 30 min to 2 h, remove acetone under reduced pressure until the solid content reaches 48-51%, then filter and discharge to obtain the third intermediate.

[0026] Step 5: Control the temperature of the third intermediate at 30-60℃, and add the thickener and defoamer to the third intermediate while stirring at 400-600 r / min. After the addition is complete, continue stirring at 400-600 r / min for 40-70 min until the viscosity reaches 5000-9000 mPa·s. Stop stirring and filter to obtain the product, which is a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive.

[0027] Compared with the prior art, the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive and its preparation method provided by the present invention have the following beneficial effects:

[0028] Because it uses a water-based polyurethane system containing a large amount of water, it is a non-flammable system with excellent flame retardant safety. The adhesive itself is non-irritating to the skin and is friendly to operators. In the synthetic raw materials, it avoids the use of volatile small molecule compounds such as triethylamine and ethylenediamine, thus avoiding odor sources and minimizing the possibility of volatilization, minimizing the impact of volatile odors on the environment and operators. Simultaneously, it introduces polyfunctional isocyanates and silane coupling agents to ensure the introduction of appropriate internal cross-linking structures during the reaction process, guaranteeing the required strength for heat creep resistance. Therefore, in addition to its excellent safety and environmental performance, such as being non-flammable, environmentally friendly, non-toxic, and low-odor, this invention also improves heat creep resistance. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them, and do not constitute a limitation on the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0030] First, the following explanations are provided for the terms that may be used in this article:

[0031] The term "and / or" means that either or both can be achieved simultaneously. For example, X and / or Y means that it includes both "X" or "Y" as well as the three cases of "X and Y".

[0032] The terms “including,” “comprising,” “containing,” “having,” or other similar semantic descriptions should be interpreted as non-exclusive inclusion. For example, “including a technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction conditions, processing conditions, parameter, algorithm, signal, data, product or article of manufacture, etc.)” should be interpreted as including not only the expressly listed technical feature element, but also other technical feature elements that are not expressly listed and are well-known in the art.

[0033] The term "composed of" excludes any technical features not expressly listed. When used in a claim, it closes the claim to exclude all technical features other than those expressly listed, except for associated conventional impurities. If the term appears only in a clause of a claim, it limits the claim to the elements expressly listed in that clause; elements recited in other clauses are not excluded from the overall claim.

[0034] The term "parts by mass" indicates the mass ratio between multiple components. For example, if component X is described as x parts by mass and component Y as y parts by mass, then the mass ratio of component X to component Y is x:y. One part by mass can represent any mass; for example, one part by mass can be expressed as 1 kg or 3.1415926 kg, etc. The sum of the parts by mass of all components is not necessarily 100 parts; it can be greater than 100 parts, less than 100 parts, or equal to 100 parts. Unless otherwise stated, parts, proportions, and percentages mentioned herein are all measured by mass.

[0035] When concentration, temperature, pressure, size, or other parameters are expressed as numerical ranges, such ranges should be understood to specifically disclose all ranges formed by any pairing of upper limits, lower limits, or preferred values ​​within that range, regardless of whether the range is explicitly stated; for example, if the numerical range "2 to 8" is stated, then that range should be interpreted to include ranges such as "2 to 7", "2 to 6", "5 to 7", "3 to 4 and 6 to 7", "3 to 5 and 7", "2 and 5 to 7", etc. Unless otherwise stated, the numerical ranges described herein include both their endpoints and all integers and fractions within that range.

[0036] This invention provides a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive, which is made from the following raw materials in parts by weight:

[0037]

[0038]

[0039] Preferably, in the above-mentioned hot melt adhesive, the polyester polyol is at least one selected from polybutylene adipate, polypropylene carbonate diol, and polyhexyl sebacate. Preferably, the number average molecular weight of the polyester polyol is 1000-3000.

[0040] Preferably, in the above-mentioned hot melt adhesive, the polyether polyol is at least one selected from polytetrahydrofuran diol and polypropylene glycol. Preferably, the number average molecular weight of the polyether polyol is 1000-2000.

[0041] Preferably, in the above-mentioned hot melt adhesive, the isocyanate is at least one selected from isoflavone diisocyanate, hexamethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0042] Preferably, in the above hot melt adhesive, the polyfunctional isocyanate is at least one of triphenylmethane triisocyanate and HDI trimer;

[0043] Preferably, in the above hot melt adhesive, the sulfonic acid isocyanate is at least one of BY-3508 or BY-3509 from Baiyuan Chemical.

[0044] Preferably, in the above-mentioned hot melt adhesive, the sulfonic acid-type hydrophilic chain extender is at least one of BY3305 and BY-3306 from Baiyuan Chemical.

[0045] Preferably, in the above-mentioned hot melt adhesive, the alcohol chain extender is at least one selected from 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, and 1,2-propanediol.

[0046] Preferably, in the above-mentioned hot melt adhesive, the catalyst is at least one of organotin catalysts, stannous octoate catalysts, and organobismuth catalysts;

[0047] Preferably, in the above-mentioned hot melt adhesive, the silane coupling agent is at least one of primary amino, secondary amino silane, and mercaptosilane.

[0048] Preferably, in the above-mentioned hot melt adhesive, the thickener is one or more of Evonik's TEGO Visco Plus 3000, Rohm and Haas's Acrysol RM8W, Acrysol RM5000, and Hefei Anke's HEUR-A and HEUR-B.

[0049] Preferably, in the above-mentioned hot melt adhesive, the defoamer is one or more of the following: BASF Foamaster 8034, BYK018, BYK019, KLAEN A200, AFCONA 2590, Sangjing Chemical SKC DF942, DF677.

[0050] This invention also provides a method for preparing the above-mentioned low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive, which specifically includes the following steps:

[0051] Step 1: According to the formulation of the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive of the present invention, weigh out the following ingredients: polyester polyol, polyether polyol, polyfunctional isocyanate, sulfonic acid isocyanate, sulfonic acid hydrophilic chain extender, alcohol chain extender, catalyst, silane coupling agent, acetone, deionized water, thickener and defoamer.

[0052] Step 2: The polyester polyol, polyether polyol, and sulfonic acid hydrophilic chain extender are added to the reaction apparatus. Dehydration is carried out for 40-60 minutes at 60-100°C and a vacuum of -0.08-0.09 MPa, followed by dehydration for 20-40 minutes at 100-110°C and a vacuum of -0.1 MPa. The temperature is then lowered to 50-60°C, and the isocyanate, polyfunctional isocyanate, sulfonic acid isocyanate, alcohol chain extender, and catalyst are added to the reaction apparatus. The reaction is carried out at 65-80°C for 1-3 hours until the -NCO content reaches 0.9%-1.3%, thus obtaining the first intermediate.

[0053] Step 3: Cool the first intermediate to 35-60°C, then add acetone to the first intermediate to adjust its viscosity, and then add deionized water for emulsification to obtain the second intermediate.

[0054] Step 4: Control the temperature of the second intermediate at 35-55°C, then add the silane coupling agent to the second intermediate, stir for 30 min to 2 h, remove acetone under reduced pressure until the solid content reaches 48-51%, then filter and discharge to obtain the third intermediate.

[0055] Step 5: Control the temperature of the third intermediate at 30-60℃, and add the thickener and defoamer to the third intermediate while stirring at 400-600 r / min. After the addition is complete, continue stirring at 400-600 r / min for 40-70 min until the viscosity reaches 5000-9000 mPa·s. Stop stirring and filter to obtain the product, which is a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive.

[0056] Compared with the prior art, the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive and its preparation method provided by the present invention have at least the following advantages:

[0057] (1) By using isocyanates and hydrophilic chain extenders containing sulfonates, and avoiding the use of carboxylate chain extenders, the use of neutralizing agent triethylamine is avoided; alcohol chain extenders are used and ethylenediamine chain extenders are avoided. In this way, the release of small molecules with strong pungent odors such as triethylamine and diethylamine during storage or under heating conditions is avoided, thus avoiding odor problems.

[0058] (2) By using specific multifunctional isocyanates and silane coupling agents in a specific ratio, the synthesized waterborne polyurethane hot melt adhesive contains a specific internal cross-linking structure, which improves the heat creep resistance and avoids problems such as spring-off, slippage, and detachment of the bonded substrate in high-temperature weather or under heating conditions, which would cause the bonded parts to be scrapped and result in serious economic losses.

[0059] (3) The water-based polyurethane hot melt adhesive prepared by this invention is a water-based emulsion containing a large amount of water. It is a non-flammable system with excellent flame retardant safety. The adhesive itself is non-irritating to the skin and is friendly to operators. It has the advantages of being environmentally friendly, non-toxic, safe, and low-odor. It can meet the requirements of environmental protection, non-toxicity, and safety, and can be applied by spraying, rolling, brushing, etc., making its application wider.

[0060] In summary, the waterborne polyurethane hot melt adhesive of the present invention has advantages such as flame retardancy, environmental friendliness, and low odor. At the same time, the present invention also has advantages such as excellent heat creep resistance.

[0061] To more clearly demonstrate the technical solution and its effects provided by the present invention, the following detailed description of the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive and its preparation method provided by the present invention is based on specific embodiments.

[0062] Example 1

[0063] This embodiment provides a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive, the preparation method of which may include the following steps:

[0064] Step A1: 160g of polybutylene adipate (number average molecular weight 2000), 3g of polypropylene glycol (number average molecular weight 2000), and 1.5g of sulfonate hydrophilic chain extender BY3305 were added to the reaction apparatus. Dehydration was carried out at 95℃ and a vacuum of -0.08MPa for 40min, followed by dehydration at 105℃ and a vacuum of -0.1MPa for 25min. The temperature was then lowered to 55℃, and 7g of hexamethylene diisocyanate, 1g of triphenylmethane triisocyanate, 8g of BY-3508, 0.3g of 1,6-hexanediol, 0.4g of neopentyl glycol, and 0.02g of dibutyltin dilaurate were added to the reaction apparatus. The reaction was carried out at 72℃ for 3 hours until the -NCO content reached 1.12%, thus obtaining the first intermediate.

[0065] Step A2: Cool the first intermediate to 50°C, then add 255g of acetone to the first intermediate to adjust the viscosity of the prepolymer, control the temperature at 45°C, and then add 240g of deionized water for emulsification to obtain the second intermediate.

[0066] Step A3: The temperature of the second intermediate is controlled at 42°C. Then, 0.6g of secondary aminosilane coupling agent is added to the second intermediate, stirred for 1 hour, and acetone is removed under reduced pressure. After the solid content reaches 50%, the material is filtered out to obtain the third intermediate.

[0067] Step A4: Control the temperature of the third intermediate at 40°C, and add 0.7g of Acrysol RM8W and 0.5g of AFCONA 2590 to the third intermediate while stirring at 500r / min. After the addition is complete, continue stirring at 500r / min for 50min until the viscosity reaches 7000mPa.s. Stop stirring and filter to obtain the product, which is a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive.

[0068] Example 2

[0069] This embodiment provides a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive, the preparation method of which may include the following steps:

[0070] In step B1, 160g of polybutylene adipate (number average molecular weight 2000), 3g of polypropylene glycol (number average molecular weight 2000), and 1.5g of sulfonate hydrophilic chain extender BY3305 were added to the reaction apparatus. The mixture was dehydrated at 95°C and a vacuum of -0.08MPa for 40 minutes, then at 105°C and a vacuum of -0.1MPa for 25 minutes. The temperature was lowered to 55°C, and then 7g of hexamethylene diisocyanate, 2g of triphenylmethane triisocyanate, 9g of BY-3509, 0.4g of 1,6-hexanediol, 0.3g of diethylene glycol, and 0.04g of dibutyltin dilaurate were added to the reaction apparatus. The mixture was reacted at 70°C for 2.5 hours until the -NCO content reached 1.10%, thus obtaining the first intermediate.

[0071] Step B2: Cool the first intermediate to 50°C, then add 260g of acetone to the first intermediate to adjust the viscosity of the prepolymer, control the temperature at 40°C, and then add 250g of deionized water for emulsification to obtain the second intermediate.

[0072] In step B3, the temperature of the second intermediate is controlled at 45°C, and then 0.5g of primary aminosilane coupling agent is added to the second intermediate. After stirring for 1.5 hours, acetone is removed under reduced pressure. After the solid content reaches 49%, the material is filtered out to obtain the third intermediate.

[0073] Step B4: The temperature of the third intermediate is controlled at 45°C. While stirring at 550 r / min, 0.8 g of TEGO Visco Plus 3000 and 0.6 g of Foamaster 8034 are added to the third intermediate. After the addition is complete, stirring is continued at 550 r / min for 1 hour until the viscosity reaches 8000 mPa·s. Stirring is then stopped. The product obtained after filtration is the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive.

[0074] Example 3

[0075] This embodiment provides a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive, the preparation method of which may include the following steps:

[0076] In step C1, 80g of polybutylene adipate (number average molecular weight 2000), 90g of polypropylene carbonate diol, 4g of polytetrahydrofuran diol (number average molecular weight 2000), and 1g of sulfonate hydrophilic chain extender BY3306 were added to the reaction apparatus. The mixture was dehydrated for 35 minutes at 95°C and a vacuum of -0.09MPa, then dehydrated for 30 minutes at 100°C and a vacuum of -0.1MPa. The temperature was lowered to 50°C, and then 4g of hexamethylene diisocyanate, 4g of isoflavone diisocyanate, 3g of HDI trimer, 10BY-3508, 0.3g of 1,4-butanediol, 0.5g of neopentyl glycol, and 0.02g of dibutyltin dilaurate were added to the reaction apparatus. The mixture was reacted at 75°C for 3 hours until the -NCO content reached 1.08%, thus obtaining the first intermediate.

[0077] Step C2: Cool the first intermediate to 50°C, then add 270g of acetone to the first intermediate to adjust the viscosity of the prepolymer, control the temperature at 45°C, and then add 260g of deionized water for emulsification to obtain the second intermediate.

[0078] In step C3, the temperature of the second intermediate is controlled at 45°C. Then, 0.4g of secondary aminosilane coupling agent and 0.2g of primary aminosilane coupling agent are added to the second intermediate. The mixture is stirred for 1 hour, and acetone is removed under reduced pressure. After the solid content reaches 51%, the mixture is filtered out to obtain the third intermediate.

[0079] In step C4, the temperature of the third intermediate is controlled at 45°C. While stirring at 600 r / min, 0.2 g of HEUR-A, 0.5 g of HEUR-B, and 0.6 g of Foamaster 8034 are added to the third intermediate. After the addition is complete, stirring is continued at 600 r / min for 50 min until the viscosity reaches 8000 mPa·s. After stirring is stopped, the product obtained after filtration is the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive.

[0080] Comparative Example 1

[0081] This comparative example provides an aqueous polyurethane hot melt adhesive, the preparation method of which may include the following steps:

[0082] Step D1: 160g of polybutylene adipate (number average molecular weight 2000), 3g of polypropylene glycol (number average molecular weight 2000), and 4g of dimethylolpropionic acid were added to the reaction apparatus. The mixture was dehydrated at 95°C and a vacuum of -0.08MPa for 40 min, and then dehydrated at 105°C and a vacuum of -0.1MPa for 25 min. The temperature was then lowered to 55°C, and 16g of hexamethylene diisocyanate, 0.3g of 1,6-hexanediol, 0.4g of neopentyl glycol, and 0.02g of dibutyltin dilaurate were added to the reaction apparatus. The mixture was reacted at 72°C for 3 hours until the -NCO content reached 1.12%, thus obtaining the first intermediate.

[0083] Step D2: Cool the first intermediate to 50°C, then add 255g of acetone to the first intermediate to adjust the viscosity of the prepolymer, control the temperature at 45°C, add 5g of triethylamine neutralizer, stir for 20 minutes, and then add 240g of deionized water for emulsification to obtain the second intermediate.

[0084] Step D3: Control the temperature of the second intermediate at 42°C, then add 0.6g of ethylenediamine to the second intermediate, stir for 1 hour, remove acetone under reduced pressure, filter out the material after the solid content reaches 50%, and thus obtain the third intermediate.

[0085] Step D4: Control the temperature of the third intermediate at 40°C, and add 0.7g of Acrysol RM8W and 0.5g of AFCONA 2590 to the third intermediate while stirring at 500r / min. After the addition is complete, continue stirring at 500r / min for 50min until the viscosity reaches 7560mPa.s. Stop stirring and filter to obtain the product, which is the water-based polyurethane hot melt adhesive.

[0086] This comparative example is intended to demonstrate that the product exhibits a strong odor after using the neutralizing agent triethylamine and the chain extender ethylenediamine. Furthermore, the lack of addition of multifunctional isocyanate and silane coupling agent results in poor heat creep resistance.

[0087] Performance testing:

[0088] The following performance tests were performed on the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesives prepared in Examples 1-3 of this invention, as well as the waterborne polyurethane hot melt adhesive prepared in the comparative example:

[0089] Odor test:

[0090] Water-based polyurethane hot melt adhesive without curing agent was placed in a sample bottle, sealed, and heated at 80°C for 2 hours. Testing then commenced, with five testers evaluating the odor. The final average value was taken as the test result, as shown in the table below:

[0091] Rating: 1 = No odor; 2 = Slight odor; 3 = Odor, but not irritating; 4 = Irritating odor; 5 = Strong irritating odor; 6 = Unbearable odor.

[0092] Heat creep test:

[0093] When using waterborne polyurethane hot melt adhesive, mix the main adhesive with Bayer's Desmodur DN waterborne isocyanate curing agent at a weight ratio of 100:5, and then stir at 500-600 rpm for 5-10 minutes until homogeneous. After applying the adhesive to ABS plastic sheets and leather, heat in a 50°C oven for 6 minutes to activate. After removing from the oven, adhere the two substrates side-by-side to form a finished product. Allow the adhesive layer to cool for 10 minutes to allow for full crystallization. Then, place it back into a 50°C oven and continue heating for 10 minutes. While in the oven, suspend a 1kg weight on the leather substrate, close the oven door, and observe and record the time it takes for the leather to be pulled off the ABS substrate. If it is not pulled off within 20 minutes, record the distance the weight has slid. The results are shown in Table 1 below.

[0094] Table 1 shows the odor and heat creep test results for each embodiment and comparative example.

[0095]

[0096] As shown in Examples 1-3, Comparative Example 1, and Table 1 of the present invention, the odor of the main adhesive prepared in Examples 1-3 is generally between level 1.5 and 2, while the odor of the comparative example reaches level 3.5. When the products prepared using Examples 1-3 of the present invention are made into parts after adhesive application and subjected to heat creep resistance testing, the leather does not tear off within 20 minutes, and the distance the weights slide is between 3.5 cm and 4 cm. In contrast, when the products prepared in the comparative example are made into parts after adhesive application and subjected to heat creep resistance testing, the leather tears off within 7 minutes.

[0097] In summary, the embodiments of this invention avoid using volatile small-molecule amine compounds such as triethylamine and ethylenediamine in the synthetic raw materials, thus avoiding odor sources. This minimizes the possibility of volatilization and reduces the impact of volatile odors on the environment and operators. Simultaneously, the introduction of polyfunctional isocyanates and silane coupling agents ensures the introduction of appropriate internal cross-linking structures during the reaction process, guaranteeing the required strength for heat creep resistance. Therefore, in addition to possessing excellent safety and environmental performance such as being non-flammable, environmentally friendly, non-toxic, and low-odor, this invention also improves heat creep resistance.

[0098] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive, characterized in that, Made from the following raw materials in parts by weight, including: 145-175 parts of polyester polyol 2-8 parts of polyether polyol, 7-9 parts isocyanate, The isocyanate is at least one of isofolone diisocyanate, hexamethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate; 1-3 parts of polyfunctional isocyanate, The polyfunctional isocyanate is at least one of triphenylmethane triisocyanate and HDI trimer; 8-10 parts of sulfonic acid isocyanate 1-2 parts of sulfonic acid-based hydrophilic chain extender Alcohol chain extender 0.4–1.7 parts, Catalyst 0.02–0.06 parts, 150-270 parts acetone 150-270 parts deionized water 0.3 to 1 part of silane coupling agent, Thickener 0.2–0.9 parts, Defoamer 0.2–0.9 parts; The number average molecular weight of the polyester polyol is 1000-3000; the polyester polyol is at least one of polybutylene adipate, polypropylene carbonate diol, and polyhexyl sebacate. The number average molecular weight of the polyether polyol is 1000-2000; the polyether polyol is at least one of polytetrahydrofuran diol and polyoxypropylene diol.

2. The low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive according to claim 1, characterized in that, The sulfonic acid isocyanate is at least one of BY-3508 and BY-3509 from Baiyuan Chemical. The sulfonic acid-type hydrophilic chain extender is at least one of BY3305 and BY-3306 from Baiyuan Chemical.

3. The low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive according to claim 1, characterized in that, The alcohol chain extender is at least one selected from 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, and 1,2-propanediol.

4. The low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive according to claim 1 or 2, characterized in that, The catalyst is at least one of organotin catalysts and organobismuth catalysts.

5. The low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive according to claim 1, characterized in that, The silane coupling agent is at least one of primary aminosilane, secondary aminosilane, and mercaptosilane.

6. The low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive according to claim 1, characterized in that, The thickener is one or more of the following: Evonik's TEGO Visco Plus 3000, Rohm and Haas's Acrysol RM8W and Acrysol RM5000, and Hefei Anke's HEUR-A and HEUR-B.

7. The low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive according to claim 1, characterized in that, The defoamer is one or more of the following: BASF Foamaster 8034, BYK018 and BYK019, KLAIN A200 and AFCONA 2590, and Sangjing Chemical SKC DF942 and DF677.

8. A method for preparing a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: According to the formulation of the low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive as described in any one of claims 1-7, weigh out the following: polyester polyol, polyether polyol, polyfunctional isocyanate, sulfonic acid isocyanate, sulfonic acid hydrophilic chain extender, alcohol chain extender, catalyst, silane coupling agent, acetone, deionized water, thickener and defoamer. Step 2: The polyester polyol, polyether polyol, and sulfonic acid hydrophilic chain extender are added to the reaction apparatus. Dehydration is carried out for 40-60 minutes at 60-100°C and a vacuum of -0.08-0.09 MPa, followed by dehydration for 20-40 minutes at 100-110°C and a vacuum of -0.1 MPa. The temperature is then lowered to 50-60°C, and the isocyanate, polyfunctional isocyanate, sulfonic acid isocyanate, alcohol chain extender, and catalyst are added to the reaction apparatus. The reaction is carried out at 65-80°C for 1-3 hours until the -NCO content reaches 0.9%-1.3%, thus obtaining the first intermediate. Step 3: Cool the first intermediate to 35-60°C, then add acetone to the first intermediate to adjust its viscosity, and then add deionized water to emulsify it to obtain the second intermediate. Step 4: Control the temperature of the second intermediate at 35-55°C, then add the silane coupling agent to the second intermediate, stir for 30 min to 2 h, remove acetone under reduced pressure until the solid content reaches 48-51%, then filter and discharge to obtain the third intermediate. Step 5: Control the temperature of the third intermediate at 30-60℃, and add the thickener and defoamer to the third intermediate while stirring at 400-600 r / min. After the addition is complete, continue stirring at 400-600 r / min for 40-70 min until the viscosity reaches 5000-9000 mPa·s. Stop stirring and filter to obtain the product, which is a low-odor, high-heat-resistant, creep-resistant waterborne polyurethane hot melt adhesive.

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