Polyurethane solvent adhesive cold-bonding positioning agent, preparation method and application thereof

Abstract

The application discloses a polyurethane solvent glue cold-bonding positioning agent, a preparation method thereof and application of the positioning agent in polyurethane solvent glue. The preparation method comprises the following steps: (1) a first polyol and a first polyisocyanate are reacted to obtain an NCO-terminated polyurethane prepolymer, and then a monohydroxyl capping agent is used for reaction capping to obtain a single NCO-terminated polyurethane prepolymer; (2) the single NCO-terminated polyurethane prepolymer is reacted with a trihydroxy chain extender at room temperature to obtain a double-functional chain extender with long-chain polyurethane branch chain modification; and (3) a second polyol, a second polyisocyanate and the double-functional chain extender are reacted to obtain a polyurethane solvent glue cold-bonding positioning agent with long-branch polyurethane modification. The cold-bonding positioning agent is added into the polyurethane solvent glue, and the open time of the glue can be obviously prolonged in the sizing process of the polyurethane solvent glue, and meanwhile, the polyurethane solvent glue has excellent peeling and heat resistance.

Description

Technical Field

[0001] This invention relates to the field of polyurethane solvent adhesive additives, specifically to a polyurethane solvent adhesive cold-bonding positioning agent, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Polyurethane solvent adhesives still hold an irreplaceable position in industries such as textiles, woodworking, automobiles, and electronics due to their excellent peel strength, simple and effective application methods, and low cost.

[0004] In some applications, polyurethane solvent adhesives may crystallize too quickly, resulting in a non-adhesive and unpositionable adhesive layer. This problem can be addressed by adjusting the polyurethane formulation to reduce the crystallization rate, but this will reduce its initial peel strength, heat resistance, and other properties. It will also increase the difficulty of producing polyurethane granules, making them harder to granulate and package.

[0005] The following existing technologies were found through a search: The patent specification with publication number CN104178078A discloses a method for preparing a rapid positioning polyurethane sealant. First, two prepolymers are obtained by polymerizing polyether polyol and polyester polyol with polyisocyanate, respectively. Plasticizer, the two prepolymers and dehydrating agent are added to a planetary stirred tank and stirred under vacuum with hot water. Then, filler is added and stirred under vacuum with cold water. Finally, coupling agent and catalyst are added and stirred to obtain polyurethane sealant.

[0006] Patent specification CN118667502A discloses a UV-curable thermoplastic polyurethane elastomer solvate and its preparation method. The solvate comprises the following components in parts by weight: diisocyanate: 20-40 parts, self-made polyester diol: 45-75 parts, chain extender: 4.5-13 parts, photoinitiator: 2-5 parts, additives: 0.5-3.0 parts, and catalyst: 0.005-0.02 parts. This patented technology introduces acrylic groups into the molecular chain of the thermoplastic polyurethane elastomer solvate through self-made polyester diol, and matches it with a photoinitiator to obtain the solvate. Summary of the Invention

[0007] This invention provides a cold-bonding positioning agent for polyurethane solvent adhesives, its preparation method, and its application. When added to polyurethane solvent adhesives, this cold-bonding positioning agent significantly increases the open time of the adhesive during the application process, while also giving the polyurethane solvent adhesives excellent peel and heat resistance properties.

[0008] The specific technical solution is as follows: In a first aspect, the present invention provides a method for preparing a polyurethane solvent-based cold-applied positioning agent, comprising the steps of: (1) The first polyol and the first polyisocyanate react to obtain an NCO-terminated polyurethane prepolymer, and then the prepolymer is terminated by a single hydroxyl end-capping agent to obtain a single NCO-terminated polyurethane prepolymer. (2) The polyurethane prepolymer with single NCO end capping reacts with a trihydroxy chain extender at room temperature to obtain a bifunctional (two hydroxyl functional groups) chain extender modified with long-chain polyurethane branches. (3) The second polyol, the second polyisocyanate and the difunctional chain extender are reacted to obtain a polyurethane solvent cold-adhesive positioning agent modified with long-branched polyurethane.

[0009] In step (2), the reaction of the single NCO-terminated polyurethane prepolymer with the trihydroxy chain extender at room temperature can control the reaction ratio and other properties, ensuring the initial peel strength and heat resistance of the resulting cold-adhesive positioning agent and the polyurethane solvent adhesive used thereon.

[0010] Preferably, in step (1), the reaction temperature of the first polyol and the first polyisocyanate is 0~100℃, further 45~55℃, for example 50℃, etc., and the time is 10~60 min, for example 30 min, etc.

[0011] Preferably, in step (1), the atmosphere in which the first polyol and the first polyisocyanate react is an inert atmosphere. In this invention, the inert atmosphere refers to an atmosphere that does not participate in the reaction, such as a nitrogen atmosphere.

[0012] Preferably, in step (1), the first polyol and the first polyisocyanate react under stirring.

[0013] Preferably, in step (1), the first polyol and the first polyisocyanate react in a solvent, wherein the solvent preferably does not participate in the reaction, and the solvent preferably includes one or more of butanone, acetone, N,N-dimethylformamide (DMF), ethyl acetate, etc.

[0014] Preferably, in step (1), the monohydroxy end-capping agent reaction end-capping process is carried out in the presence of a catalyst. The amount of catalyst can be in the ppm range, for example, 5 ppm, based on the total mass of the reaction system during the end-capping process. The catalyst can be added after dilution with a solvent, which preferably does not participate in the reaction. The solvent preferably includes one or more of butanone, acetone, N,N-dimethylformamide, ethyl acetate, etc. The catalyst preferably includes dibutyltin dilaurate, etc.

[0015] Preferably, in step (1), the reaction time of the monohydroxy end-capping agent is 10~60 min, for example 30 min.

[0016] Preferably, in step (2), a trihydroxy chain extender is added to the polyurethane prepolymer mixture with single NCO end capping obtained in step (1).

[0017] Preferably, in step (2), the reaction time of the single NCO-terminated polyurethane prepolymer with the trihydroxy chain extender at room temperature is 10~60 min, for example 30 min.

[0018] Preferably, in step (3), the second polyol, the second polyisocyanate and the difunctional chain extender react in a solvent, wherein the solvent preferably does not participate in the reaction, and the solvent preferably includes one or more of butanone, acetone, N,N-dimethylformamide, ethyl acetate, etc.

[0019] Preferably, in step (3), the reaction temperature of the second polyol, the second polyisocyanate and the difunctional chain extender is 0~100℃, further 45~55℃, for example 50℃, etc., and the time is 3~4 hours, for example 3.5 hours, etc.

[0020] Preferably, in step (3), the second polyol and the second polyisocyanate react for a period of time before reacting with the difunctional chain extender. More preferably, the second polyol and the second polyisocyanate react for a period of time before the difunctional chain extender mixture obtained in step (2) is added. The preferred temperature for the initial reaction of the second polyol and the second polyisocyanate is 0~100℃, more preferably 45~55℃, for example 50℃, etc., and the preferred time is 10~60 min, for example 30 min, etc. The preferred atmosphere for the initial reaction of the second polyol and the second polyisocyanate is an inert atmosphere.

[0021] Preferably, in step (3), the reaction with the bifunctional chain extender is carried out in the presence of a catalyst. The amount of catalyst can be in the ppm range, for example, 10 ppm, based on the total mass of the reaction system during the reaction with the bifunctional chain extender. The catalyst can be added after dilution with a solvent, which preferably does not participate in the reaction. The solvent preferably includes one or more of butanone, acetone, N,N-dimethylformamide, ethyl acetate, etc. The catalyst preferably includes dibutyltin dilaurate, etc.

[0022] In step (1), the molar ratio of the hydroxyl groups in the first polyol to the isocyanate groups (-NCO) in the first polyisocyanate determines the length of the polyurethane side chains modified on the polyurethane solvent-based cold-bonding positioner. This length of polyurethane side chains determines the peel strength, heat resistance, open time, and other properties that the cold-bonding positioner can produce after being applied to the polyurethane solvent-based adhesive. Longer polyurethane side chains result in better peel strength, heat resistance, open time, and other properties after the cold-bonding positioner is applied to the polyurethane solvent-based adhesive. Therefore, in step (1), the molar ratio of the hydroxyl groups in the first polyol to the isocyanate groups in the first polyisocyanate is preferably 1:1.1~2, and more preferably 1:1.1~1.5.

[0023] Preferably, the molar amount of the monohydroxy end-capping agent in step (1) is half the molar amount of isocyanate groups in the NCO-terminated polyurethane prepolymer.

[0024] Preferably, the molar amount of the trihydroxy chain extender in step (2) is half the molar amount of isocyanate groups in the NCO-terminated polyurethane prepolymer described in step (1).

[0025] Preferably, in step (3), the molar ratio of the hydroxyl group in the second polyol to the isocyanate group in the second polyisocyanate is 1:(1+X), and the molar ratio of the hydroxyl group in the bifunctional chain extender to the isocyanate group in the second polyisocyanate is X:(1+X), where X is 0.15~0.16.

[0026] In this invention, preferably, the first polyol includes a diol, specifically one or more of polyester-based diols, polycaprolactone-based diols, polycarbonate-based diols, and polyether-based diols, such as polybutylene adipate diol.

[0027] In this invention, preferably, the number average molecular weight of the first polyol is 300~4000 g / mol, for example 1000 g / mol.

[0028] In this invention, preferably, the first polyisocyanate includes a diisocyanate, specifically including at least one of diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isoflurone diisocyanate (IPDI), and toluene diisocyanate (TDI).

[0029] In this invention, preferably, the second polyol includes a diol, specifically one or more of polyester-based diols, polycaprolactone-based diols, polycarbonate-based diols, and polyether-based diols, such as polybutylene adipate diol.

[0030] In this invention, preferably, the number-average molecular weight of the second polyol is 300-4000 g / mol.

[0031] In this invention, preferably, the second polyisocyanate includes a diisocyanate, specifically including at least one of diphenylmethane diisocyanate, hexamethylene diisocyanate, isoflurone diisocyanate, and toluene diisocyanate.

[0032] In this invention, preferably, the monohydroxy end-capping agent includes one or more of triethylene glycol monobutyl ether, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, and propylene glycol butyl ether.

[0033] In this invention, preferably, the trihydroxy chain extender includes one or more of glycerol, trimethylolpropane, polyether triol, and polycaprolactone triol.

[0034] Preferably, the number-average molecular weight of the polyether triol is 400~1000 g / mol.

[0035] Preferably, the number-average molecular weight of the polycaprolactone triol is 100~1000 g / mol.

[0036] Secondly, the present invention provides a polyurethane solvent-based cold-applied positioning agent prepared by the preparation method described in the first aspect.

[0037] Thirdly, the present invention provides the application of the polyurethane solvent adhesive cold-bonding positioning agent described in the second aspect in polyurethane solvent adhesives.

[0038] Fourthly, the present invention provides a polyurethane solvent adhesive, comprising the polyurethane solvent adhesive cold-bonding positioning agent described in the second aspect.

[0039] In the applications described in the third aspect and the polyurethane solvent adhesives described in the fourth aspect, the cold-adhesive positioning agent has a mass percentage content of 10% to 20% in the polyurethane solvent adhesive.

[0040] Compared with the prior art, the beneficial effects of this invention are as follows: 1. The polyurethane solvent adhesive cold-bonding positioning agent of the present invention is a thermoplastic polyurethane modified with long-branched polyurethane that has excellent peel and heat resistance. It has good solubility. When added to polyurethane solvent adhesive, it can make the polyurethane solvent adhesive have excellent peel and heat resistance properties as well as a long open time, thus achieving a cold-bonding effect.

[0041] 2. This invention obtains a long-chain polyurethane prepolymer with single NCO end-capping agent, and then grafts it onto the long chain of thermoplastic polyurethane using a trihydroxy chain extender to form a polyurethane solvent adhesive cold-tack positioning agent. When this cold-tack positioning agent is added to the polyurethane solvent adhesive, the presence of long-chain polyurethane grafts makes the polyurethane solvent adhesive an exceptionally slow-crystallizing cold-tack adhesive that can achieve room temperature adhesion. At the same time, the presence of long side-chain polyurethane gives the polyurethane solvent adhesive excellent strength and heat resistance, effectively improving the open time and achieving room temperature positioning.

[0042] 3. The operation method of this invention is simple, low-cost, universally applicable, and easy to scale up for production. Detailed Implementation

[0043] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0044] Unless otherwise specified, the molecular weights in the following examples are exponential molecular weights, and the units are g / mol.

[0045] Example 1: (1) 39.2 g of polybutylene adipate diol (molecular weight 1000) and 10.8 g of isocyanate MDI were added to a three-necked flask containing 50 g of butanone. The mixture was stirred and reacted under nitrogen protection at 50 degrees Celsius for 30 min to obtain an NCO-terminated polyurethane prepolymer. 0.82 g of triethylene glycol monobutyl ether, a monohydroxy end-capping agent, and 5 ppm of dibutyltin dilaurate catalyst (calculated based on the total mass of the solution, the catalyst was diluted with butanone before addition) were added. The reaction was continued for 30 min to obtain a mono-NCO-terminated polyurethane prepolymer.

[0046] (2) In the prepolymer solution with single NCO end cap obtained in step (1), stir at room temperature, add 0.54 g of trihydroxy chain extender trimethylolpropane (TMP), react for 30 min, and react quantitatively with the prepolymer with single NCO end cap obtained in step (1) to obtain a bifunctional chain extender modified with long-chain polyurethane branches.

[0047] (3) Add 23.5g of polybutylene adipate diol (molecular weight 1000) and 6.8g of isocyanate MDI to a three-necked flask containing 25g of butanone. Under nitrogen protection, react at 50 degrees Celsius for 30 minutes. Then, add the bifunctional chain extender solution obtained in steps (1) and (2) to the reaction according to the product R value (-NCO:-OH molar ratio) 1:1. At the same time, add 10ppm of catalyst dibutyltin dilaurate (calculated according to the total mass of the solution, the catalyst is added after being diluted with butanone). React at 50 degrees Celsius for 3 hours to obtain a thermoplastic polyurethane adhesive solution modified with long branched polyurethane that has good solubility and excellent heat resistance for peeling. It can be used as a cold-adhesive positioning agent to be added to polyurethane adhesive.

[0048] Example 2: (1) 33.3 g of polybutylene adipate diol (molecular weight 1000) and 16.6 g of isocyanate MDI were added to a three-necked flask containing 50 g of butanone. The mixture was stirred and reacted under nitrogen protection at 50 degrees Celsius for 30 min to obtain an NCO-terminated polyurethane prepolymer. 6.8 g of triethylene glycol monobutyl ether, a monohydroxy end-capping agent, and 5 ppm of dibutyltin dilaurate catalyst (calculated based on the total mass of the solution, the catalyst was diluted with butanone before addition) were added, and the reaction was continued for 30 min to obtain a mono-NCO-terminated polyurethane prepolymer.

[0049] (2) In the prepolymer solution with single NCO end cap obtained in step (1), stir at room temperature, add 4.4 g of trihydroxy chain extender trimethylolpropane (TMP), react for 30 min, and react quantitatively with the prepolymer with single NCO end cap obtained in step (1) to obtain a bifunctional chain extender modified with long-chain polyurethane branches.

[0050] (3) Add 158g of polybutylene adipate diol (molecular weight 1000) and 45.5g of isocyanate MDI to a three-necked flask containing 170g of butanone. Under nitrogen protection, react at 50 degrees Celsius for 30 minutes. Then, add the bifunctional chain extender solution obtained in steps (1) and (2) to the reaction according to the product R value (-NCO:-OH molar ratio) 1:1. At the same time, add 10ppm of catalyst dibutyltin dilaurate (calculated according to the total mass of the solution, the catalyst is added after being diluted with butanone). React at 50 degrees Celsius for 3 hours to obtain a cold-adhesive positioning agent.

[0051] Example 3: (1) 36.3 g of polybutylene adipate diol (molecular weight 1000) and 13.6 g of isocyanate MDI were added to a three-necked flask containing 50 g of butanone. The mixture was stirred and reacted under nitrogen protection at 50 degrees Celsius for 30 min to obtain an NCO-terminated polyurethane prepolymer. 3.7 g of triethylene glycol monobutyl ether, a monohydroxy end-capping agent, and 5 ppm of dibutyltin dilaurate catalyst (calculated based on the total mass of the solution; the catalyst was diluted with butanone before addition) were added. The reaction was continued for 30 min to obtain a mono-NCO-terminated polyurethane prepolymer.

[0052] (2) In the prepolymer solution with single NCO end cap obtained in step (1), stir at room temperature, add 2.4 g of trihydroxy chain extender trimethylolpropane (TMP), react for 30 min, and react quantitatively with the prepolymer with single NCO end cap obtained in step (1) to obtain a bifunctional chain extender modified with long-chain polyurethane branches.

[0053] (3) Add 87.4g of polybutylene adipate diol (molecular weight 1000) and 25.3g of isocyanate MDI to a three-necked flask containing 94g of butanone. Under nitrogen protection, react at 50 degrees Celsius for 30 minutes. Then, add the bifunctional chain extender solution obtained in steps (1) and (2) to the reaction according to the product R value (-NCO:-OH molar ratio) 1:1. At the same time, add 10ppm of catalyst dibutyltin dilaurate (calculated according to the total mass of the solution, the catalyst is added after being diluted with butanone). React at 50 degrees Celsius for 3 hours to obtain a cold-adhesive positioning agent.

[0054] Example 4: (1) 39.2 g of polybutylene adipate diol (molecular weight 1000) and 10.8 g of isocyanate MDI were added to a three-necked flask containing 50 g of butanone. The mixture was stirred and reacted under nitrogen protection at 50 degrees Celsius for 30 min to obtain an NCO-terminated polyurethane prepolymer. 0.82 g of triethylene glycol monobutyl ether, a monohydroxy end-capping agent, and 5 ppm of dibutyltin dilaurate catalyst (calculated based on the total mass of the solution, the catalyst was diluted with butanone before addition) were added. The reaction was continued for 30 min to obtain a mono-NCO-terminated polyurethane prepolymer.

[0055] (2) In the prepolymer solution with single NCO end caps obtained in step (1), stir at 50 degrees and add 0.54 g of trihydroxy chain extender trimethylolpropane (TMP). React for 30 min to obtain the modified chain extender.

[0056] (3) Add 23.5g of polybutylene adipate diol (molecular weight 1000) and 6.8g of isocyanate MDI to a three-necked flask containing 25g of butanone. Under nitrogen protection, react at 50 degrees Celsius for 30 minutes. Then, add the bifunctional chain extender solution obtained in steps (1) and (2) to the reaction according to the product R value (-NCO:-OH molar ratio) 1:1. At the same time, add 10ppm of catalyst dibutyltin dilaurate (calculated according to the total mass of the solution, the catalyst is added after being diluted with butanone). React at 50 degrees Celsius for 3 hours to obtain a cold-adhesive positioning agent.

[0057] The cold-bonding positioning agents obtained in each embodiment were added to the polyurethane solvent shoe adhesive at a mass of 15% of the polyurethane solvent shoe adhesive. All solutions dissolved well. After application, initial tack testing was conducted according to the test methods specified in GB / T 19340-2014 Adhesives for Shoes and Bags. The initial peel strength was obtained by pressing at 70 degrees Celsius for 10 minutes. Heat resistance was tested according to HG / T2815-1996 Heat Resistance Test for Shoe Adhesives. After bonding at 70 degrees Celsius for 24 hours, a 500g weight was attached, and the sample was tested in a 70-degree Celsius oven for 10 minutes to obtain the heat-resistant displacement. The open time (adhesive release time) of the test piece was tested after baking at 70 degrees Celsius for 10 minutes. Specific test results are shown in Table 1 below.

[0058] Table 1 The test results in the table above show that: Example 1, due to the presence of long polyurethane side chains, can effectively improve the open time and significantly improve the heat resistance; in Examples 2 and 3, the polyurethane side chain length is shorter than that in Example 1, and the effect is not as obvious as that in Example 1; in Example 4, the reaction between the trihydroxy chain extender and the monohydroxy NCO chain cannot be controlled, resulting in an abnormal reaction ratio, a longer open time, but poorer performance, which affects the performance of the adhesive.

[0059] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for preparing a polyurethane solvent-based cold-applied positioning agent, characterized in that, Including the following steps: (1) The first polyol and the first polyisocyanate react to obtain an NCO-terminated polyurethane prepolymer, and then the prepolymer is terminated by a single hydroxyl end-capping agent to obtain a single NCO-terminated polyurethane prepolymer. (2) The polyurethane prepolymer with single NCO end capping reacts with a trihydroxy chain extender at room temperature to obtain a bifunctional chain extender modified with long-chain polyurethane branches. (3) The second polyol, the second polyisocyanate and the difunctional chain extender are reacted to obtain a polyurethane solvent cold-adhesive positioning agent modified with long-branched polyurethane.

2. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of the hydroxyl group in the first polyol to the isocyanate group in the first polyisocyanate is 1:1.1~2.

3. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of the hydroxyl group in the first polyol to the isocyanate group in the first polyisocyanate is 1:1.1~1.

5.

4. The preparation method according to claim 1, characterized in that, In step (1), the molar amount of the monohydroxy end-capping agent is half the molar amount of isocyanate groups in the NCO-terminated polyurethane prepolymer. In step (2), the molar amount of the trihydroxy chain extender is half the molar amount of isocyanate groups in the NCO-terminated polyurethane prepolymer described in step (1).

5. The preparation method according to claim 1, characterized in that, In step (3), the molar ratio of the hydroxyl group in the second polyol to the isocyanate group in the second polyisocyanate is 1:(1+X), and the molar ratio of the hydroxyl group in the bifunctional chain extender to the isocyanate group in the second polyisocyanate is X:(1+X), where X is 0.15~0.

16.

6. The preparation method according to claim 1, characterized in that, The first polyol is one or more of polyester-based diol, polycaprolactone-based diol, polycarbonate-based diol, and polyether-based diol; The number-average molecular weight of the first polyol is 300~4000 g / mol; The first polyisocyanate is at least one of diphenylmethane diisocyanate, hexamethylene diisocyanate, isoflurone diisocyanate, and toluene diisocyanate; The second polyol is one or more of polyester-based diols, polycaprolactone-based diols, polycarbonate-based diols, and polyether-based diols; The number-average molecular weight of the second polyol is 300~4000 g / mol; The second polyisocyanate is at least one of diphenylmethane diisocyanate, hexamethylene diisocyanate, isoflurone diisocyanate, and toluene diisocyanate.

7. The preparation method according to claim 1, characterized in that, The monohydroxy end-capping agent includes one or more of triethylene glycol monobutyl ether, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, and propylene glycol butyl ether.

8. The preparation method according to claim 1, characterized in that, The trihydroxy chain extender includes one or more of glycerol, trimethylolpropane, polyether triol, and polycaprolactone triol; The number-average molecular weight of the polyether triol is 400~1000 g / mol; The number-average molecular weight of the polycaprolactone triol is 100~1000 g / mol.

9. The polyurethane solvent-based cold-applied positioning agent prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the polyurethane solvent adhesive cold-bonding positioning agent according to claim 9 in polyurethane solvent adhesives.

11. A polyurethane solvent adhesive, characterized in that, Includes the polyurethane solvent-based cold-applied positioning agent as described in claim 9.

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