High-temperature-resistant TPU (thermoplastic polyurethane) hot melt adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of polymer adhesive materials. The invention relates to a hot melt adhesive, in particular to a high-temperature-resistant TPU hot melt adhesive and a preparation method thereof. During preparation of the product, the preparation method comprises the following steps: dehydrating polyester polyol, and preheating to 70-75 DEG C under the protection of inert gas to obtain preheated polyester polyol; the preparation method comprises the following steps: heating and melting diphenylmethane diisocyanate to obtain molten isocyanate; the preparation method comprises the following steps: mixing molten isocyanate and preheated polyester polyol, carrying out heat preservation reaction for 100-120 minutes at the temperature of 70-75 DEG C, heating to 80-85 DEG C, adding a chain extender aromatic diamine, continuously carrying out heat preservation reaction for 40-60 minutes, sequentially adding a defoaming agent, an antioxidant, an anti-hydrolysis agent and a filler, continuously stirring uniformly, curing for 100-120 minutes at the temperature of 100-110 DEG C, discharging, and cooling, thereby obtaining a finished product. The high-temperature-resistant TPU hot melt adhesive is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer adhesive materials and more specifically relates to a high temperature resistant TPU hot melt adhesive and a preparation method thereof. Background Art

[0002] TPU hot melt adhesive is a hot melt adhesive product made of thermoplastic polyurethane (TPU) as the main raw material. It has many excellent physical and chemical properties and is therefore widely used in industrial manufacturing and product development.

[0003] TPU hot melt adhesive is usually bonded by pressing equipment, and the appropriate temperature and time need to be controlled to ensure the bonding effect. For example, the melting point of TPU hot melt adhesive is about 120-150℃, and the pressing time is 10-20 seconds. Before use, the bonding surface needs to be pre-treated to ensure the bonding effect.

[0004] During actual product use, it is necessary to improve the stability of the product during high-temperature storage to avoid the impact of long-term high-temperature environment on the product's bonding performance. Summary of the invention

[0005] The technical problem to be solved by the present invention is: for a thermoplastic polyurethane hot melt adhesive system, its thermal stability during product processing or storage is insufficient, thereby affecting the bonding performance of the product during long-term use. The present invention provides a high-temperature resistant TPU hot melt adhesive and a preparation method thereof.

[0006] The purpose of the invention is to provide a high temperature resistant TPU hot melt adhesive.

[0007] Another object of the present invention is to provide a method for preparing a high temperature resistant TPU hot melt adhesive.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing a high temperature resistant TPU hot melt adhesive, the specific preparation steps comprising:

[0010] After dehydration treatment, the polyester polyol is preheated to 70-75° C. under inert gas protection to obtain preheated polyester polyol;

[0011] Heat and melt diphenylmethane diisocyanate to obtain molten isocyanate;

[0012] After mixing the molten isocyanate and the preheated polyester polyol, keep the mixture at 70-75°C for 100-120 minutes, then heat to 80-85°C, add the chain extender aromatic diamine, keep the mixture at 40-60 minutes, add the defoamer, antioxidant, anti-hydrolysis agent and filler in turn, stir evenly, mature at 100-110°C for 100-120 minutes, discharge, and cool to obtain the high temperature resistant TPU hot melt adhesive;

[0013] Wherein, the molar ratio of the polyester polyol, the diphenylmethane diisocyanate and the chain extender aromatic diamine is (70-75): (10-12): (20-22).

[0014] For the above technical scheme, by adopting a certain ratio of polyester polyol, diphenylmethane diisocyanate and aromatic diamine chain extender, and matching corresponding processing conditions, it is ensured that in the prepared thermoplastic polyurethane hot melt adhesive system, the molecular chain length distribution of the polyurethane resin is relatively uniform, and the molecular weight distribution is relatively uniform, which is more conducive to the compatibility between the hard segment (the rigid part formed by diphenylmethane diisocyanate and the chain extender) and the soft segment (the flexible part formed by the polyester polyol). In this way, the hard segment and the soft segment in the molecular chain of the polyurethane resin can be Microphase separation is formed between the hard segments. The aggregates of the hard segments can serve as physical training points to increase the material's stability and resist thermal degradation under high temperature conditions, while the soft segments provide the necessary flexibility, allowing the material to better disperse stress when subjected to thermal or mechanical stress. The relative uniformity of the molecular chain length or molecular weight makes the distribution of soft and hard segments more uniform, giving the product more uniform physical and chemical properties, and can effectively reduce defects in the molecular chain, such as chain branching and chain termination (these defects may become the starting point of thermal degradation at high temperatures), thereby improving the overall thermal stability of the product.

[0015] Furthermore, the amount of the filler is 10-15% of the mass of the polyester polyol;

[0016] The filler is monodisperse boehmite; and the particle size distribution range of the monodisperse boehmite is 10-20 μm.

[0017] The above scheme further adds a certain amount of monodisperse boehmite as a filler, and adopts single-molecule boehmite with a narrow particle size distribution range as a filler. From a macroscopic perspective, it can make it easier for the hot melt adhesive to form a film of uniform thickness during the film formation process. From a microscopic perspective, it can make the distribution of fillers and resins in the adhesive layers in different regions relatively balanced, so that the physical and chemical properties of different regions of the film as a whole are relatively balanced, thereby avoiding insufficient local thermal stability caused by weak local physical and chemical properties during use, which leads to overall bonding failure of the product.

[0018] Furthermore, the preparation steps of the monodisperse boehmite include:

[0019] The boehmite and water are mixed, ultrasonically dispersed, and then a silane coupling agent of 8-10% of the mass of the boehmite is added. After heating and stirring for reaction, the mixture is spray-dried and sieved to obtain the monodisperse boehmite.

[0020] By pretreating boehmite with a coupling agent, the interfacial compatibility between boehmite and the polyurethane resin can be improved, thereby further improving its dispersion in the resin system. In particular, the above scheme further adopts spray drying to remove solvent water and other substances. During the spray drying process, spherical particles with a large specific surface area are easily formed, which helps it to obtain better fluidity when added to the resin system, thereby facilitating its dispersion. In addition, the spherical particles have similar physical and chemical properties at different angles, which is also beneficial to improving the overall performance uniformity of the hot melt adhesive.

[0021] Furthermore, the silane coupling agent is selected from any one of silane coupling agent KH-540, silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570, and silane coupling agent KH-580.

[0022] Furthermore, the polyester polyol is selected from any one of poly(1,4-butylene adipate), poly(1,6-hexane adipate) and poly(diethylene adipate).

[0023] Further, the defoamer is selected from any one of BYK-141, BYK-065, BYK-066, BYK-051, and BYK-052;

[0024] Furthermore, the defoaming agent is used in an amount of 0.12-0.20% of the mass of the polyester polyol;

[0025] The antioxidant is selected from any one of antioxidant V-900, antioxidant V-902, and antioxidant V-800;

[0026] Furthermore, the amount of the antioxidant is 0.04-0.06% of the mass of the polyester polyol;

[0027] The anti-hydrolysis agent is selected from any one of N,N'-diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, dicyclohexylcarbodiimide, and N,N'-tetramethylbenzene bis[2,6-bis(1-methylethyl)aniline];

[0028] Furthermore, the dosage of the anti-hydrolysis agent is 0.03-0.05% of the mass of the polyester polyol.

[0029] A high temperature resistant TPU hot melt adhesive is prepared by the above preparation method. DETAILED DESCRIPTION

[0030] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0031] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0032] Example 1

[0033] Boehmite and water are mixed in a mass ratio of 1:5, wherein the boehmite is selected to have a D50 of 0.1 μm, and ultrasonic dispersion is performed for 40 minutes at an ultrasonic frequency of 120 kHz, and then a silane coupling agent of 8% by mass of the boehmite is added, and then heated and stirred for reaction for 2 hours at a temperature of 75°C and a stirring speed of 400 r / min, and then transferred to a spray dryer, and the feed rate is 80 g / min, and spray drying and sieving are performed at an inlet air temperature of 130°C, an outlet air temperature of 100°C, and a main disk speed of 8000 r / min to obtain a monodisperse boehmite with a particle size distribution range of 10-20 μm;

[0034] The polyester polyol was subjected to reduced pressure distillation and dehydration for 4 hours at a vacuum degree of 0.09 MPa and a temperature of 100° C., and then preheated to 70° C. under argon gas protection to obtain preheated polyester polyol;

[0035] Heat and melt diphenylmethane diisocyanate to obtain molten isocyanate;

[0036] After the molten isocyanate and the preheated polyester polyol are mixed, the mixture is kept warm for 100 minutes at 70°C, then heated to 80°C, and the chain extender aromatic diamine is added. After the mixture is kept warm for 40 minutes, the defoamer, antioxidant, anti-hydrolysis agent and filler are added in sequence. After the mixture is stirred at 300 r / min for 30 minutes with a stirrer, the mixture is aged for 100 minutes at 100°C, discharged, and cooled to obtain a high temperature resistant TPU hot melt adhesive.

[0037] Wherein, the molar ratio of the polyester polyol, the diphenylmethane diisocyanate and the chain extender aromatic diamine is 70:10:20;

[0038] The amount of the filler is 10% of the mass of the polyester polyol; the filler is monodisperse boehmite;

[0039] The silane coupling agent is selected from silane coupling agent KH-540;

[0040] The polyester polyol is selected from poly(1,4-butylene adipate);

[0041] The defoamer is selected from BYK-141;

[0042] Furthermore, the defoaming agent is used in an amount of 0.12% of the mass of the polyester polyol;

[0043] The antioxidant is selected from antioxidant V-900;

[0044] Furthermore, the amount of the antioxidant is 0.04% by mass of the polyester polyol;

[0045] The anti-hydrolysis agent is selected from N,N'-diisopropylcarbodiimide;

[0046] Furthermore, the dosage of the anti-hydrolysis agent is 0.03% of the mass of the polyester polyol.

[0047] Example 2

[0048] Boehmite and water are mixed in a mass ratio of 1:5, wherein the boehmite is selected to have a D50 of 0.2 μm, and ultrasonic dispersion is performed for 50 min at an ultrasonic frequency of 130 kHz, and then a silane coupling agent of 9% by mass of the boehmite is added, and then heated and stirred for reaction for 2 h at a temperature of 78° C. and a stirring speed of 400 r / min, and then transferred to a spray dryer, and fed at a feeding rate of 80 g / min, and spray dried and sieved at an inlet air temperature of 135° C., an outlet air temperature of 105° C., and a main disk speed of 8000 r / min to obtain a monodisperse boehmite with a particle size distribution range of 10-20 μm;

[0049] The polyester polyol was subjected to reduced pressure distillation and dehydration for 4 hours at a vacuum degree of 0.09 MPa and a temperature of 100° C., and then preheated to 72° C. under argon gas protection to obtain preheated polyester polyol;

[0050] Heat and melt diphenylmethane diisocyanate to obtain molten isocyanate;

[0051] After the molten isocyanate and the preheated polyester polyol are mixed, the mixture is kept warm for 110 minutes at 72°C, and then heated to 82°C, and the chain extender aromatic diamine is added, and the mixture is kept warm for 50 minutes, and then the defoamer, antioxidant, anti-hydrolysis agent and filler are added in sequence, and the mixture is stirred at 300 r / min for 30 minutes with a stirrer, and then aged at 105°C for 110 minutes, discharged, and cooled to obtain a high temperature resistant TPU hot melt adhesive;

[0052] Wherein, the molar ratio of the polyester polyol, the diphenylmethane diisocyanate and the chain extender aromatic diamine is 72:11:21;

[0053] The amount of the filler is 12% of the mass of the polyester polyol; the filler is monodisperse boehmite;

[0054] The silane coupling agent is selected from silane coupling agent KH-550;

[0055] The polyester polyol is selected from poly-1,6-hexanediol adipate;

[0056] The defoamer is selected from BYK-065;

[0057] Furthermore, the defoaming agent is used in an amount of 0.16% of the mass of the polyester polyol;

[0058] The antioxidant is selected from antioxidant V-902;

[0059] Furthermore, the amount of the antioxidant is 0.05% of the mass of the polyester polyol;

[0060] The anti-hydrolysis agent is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride;

[0061] Furthermore, the dosage of the anti-hydrolysis agent is 0.04% of the mass of the polyester polyol.

[0062] Example 3

[0063] Boehmite and water are mixed in a mass ratio of 1:5, wherein the boehmite is selected to have a D50 of 0.2 μm, and ultrasonic dispersion is performed for 60 min at an ultrasonic frequency of 130 kHz, and then a silane coupling agent of 10% by mass of the boehmite is added, and then heated and stirred for reaction for 2 h at a temperature of 80° C. and a stirring speed of 400 r / min, and then transferred to a spray dryer, and the feed rate is 80 g / min, and the feed rate is 80 g / min, and the feed rate is spray-dried and sieved at an inlet air temperature of 140° C., an outlet air temperature of 110° C., and a main disk speed of 8000 r / min, so as to obtain a monodisperse boehmite with a particle size distribution range of 10-20 μm;

[0064] The polyester polyol was subjected to reduced pressure distillation and dehydration for 4 hours at a vacuum degree of 0.09 MPa and a temperature of 100° C., and then preheated to 75° C. under argon gas protection to obtain preheated polyester polyol;

[0065] Heat and melt diphenylmethane diisocyanate to obtain molten isocyanate;

[0066] After the molten isocyanate and the preheated polyester polyol are mixed, the mixture is kept warm for 120 minutes at 75°C, and then heated to 85°C, and the chain extender aromatic diamine is added, and the mixture is kept warm for 60 minutes, and then the defoamer, antioxidant, anti-hydrolysis agent and filler are added in sequence, and the mixture is stirred at 300r / min for 30 minutes with a stirrer, and then aged at 110°C for 120 minutes, discharged, and cooled to obtain a high temperature resistant TPU hot melt adhesive;

[0067] Wherein, the molar ratio of the polyester polyol, the diphenylmethane diisocyanate and the chain extender aromatic diamine is 75:12:22;

[0068] The amount of the filler is 15% of the mass of the polyester polyol; the filler is monodisperse boehmite;

[0069] The silane coupling agent is selected from silane coupling agent KH-560;

[0070] The polyester polyol is selected from polyethylene adipate;

[0071] The defoamer is selected from BYK-066;

[0072] Furthermore, the defoaming agent is used in an amount of 0.20% of the mass of the polyester polyol;

[0073] The antioxidant is selected from antioxidant V-800;

[0074] Furthermore, the amount of the antioxidant is 0.06% of the mass of the polyester polyol;

[0075] The anti-hydrolysis agent is selected from dicyclohexylcarbodiimide;

[0076] Furthermore, the dosage of the anti-hydrolysis agent is 0.05% of the mass of the polyester polyol.

[0077] Example 4

[0078] The present embodiment is different from the embodiment 1 in that the particle size distribution range of the monodisperse boehmite is 5-30 μm, and the other conditions remain unchanged.

[0079] Example 5

[0080] Compared with Example 1, this embodiment is different in that:

[0081] Boehmite and water are mixed in a mass ratio of 1:5, wherein the boehmite is selected to have a D50 of 8 μm, and ultrasonic dispersion is performed for 40 minutes at an ultrasonic frequency of 120 kHz, and then a silane coupling agent of 8% by mass of the boehmite is added, and then heated and stirred for reaction for 2 hours at a temperature of 75° C. and a stirring speed of 400 r / min, and then filtered to collect the filter cake, and the obtained filter cake is dried to constant weight at a temperature of 100° C., broken up, and sieved to obtain monodisperse boehmite with a particle size distribution range of 10-20 μm;

[0082] The rest of the conditions remain unchanged.

[0083] Example 6

[0084] Compared with Example 1, this embodiment differs in that no filler is added and other conditions remain unchanged.

[0085] Comparative Example 1

[0086] The difference between this comparative example and Example 1 is that an equal amount of 1,4-butanediol is used to replace the aromatic diamine as a chain extender, and other conditions remain unchanged.

[0087] The performance tests were performed on the products obtained in the above examples and comparative examples. The specific test methods and test results are as follows:

[0088] A PVC plastic substrate with a specification of 120 mm×30 mm×2 mm was selected, and the hot melt adhesive product obtained in the above embodiments or comparative examples was coated on the surface of the substrate with a coating thickness of 1 mm. After the adhesive was cooled and solidified, the bonding strength was measured by a universal testing machine according to ASTM D 1002.

[0089] A PVC plastic substrate with a specification of 120 mm × 30 mm × 2 mm was selected, and the hot melt adhesive product obtained in the above embodiments or comparative examples was coated on the surface of the substrate with a coating thickness of 1 mm. After the adhesive was cooled and solidified, it was subjected to a wet heat aging treatment at a temperature of 50° C. and a relative humidity of 75% for 14 days, and then the bonding strength was measured again using a universal testing machine according to ASTM D1002.

[0090] The detailed test results are shown in Table 1;

[0091] Table 1: Product performance test results

[0092] Bond strength 1 / MPa Bond strength 2 / MPa Example 1 28.98 27.86 Example 2 29.02 27.99 Example 3 29.11 28.20 Example 4 28.95 27.61 Example 5 28.92 27.53 Example 6 24.15 22.98 Comparative Example 1 27.01 25.44

[0093] It can be seen from the test results in Table 1 that the product obtained by the present invention can obtain relatively more beneficial thermal stability, and still has good bonding strength retention after long-term wet heat aging.

[0094] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing high temperature resistant TPU hot melt adhesive, It is characterized in that The specific preparation steps include: After dehydration treatment, the polyester polyol is preheated to 70-75° C. under inert gas protection to obtain preheated polyester polyol; Heat and melt diphenylmethane diisocyanate to obtain molten isocyanate; After mixing the molten isocyanate and the preheated polyester polyol, keep the mixture at 70-75°C for 100-120 minutes, then heat to 80-85°C, add the chain extender aromatic diamine, keep the mixture at 40-60 minutes, add the defoamer, antioxidant, anti-hydrolysis agent and filler in turn, stir evenly, mature at 100-110°C for 100-120 minutes, discharge, and cool to obtain the high temperature resistant TPU hot melt adhesive; Wherein, the molar ratio of the polyester polyol, the diphenylmethane diisocyanate and the chain extender aromatic diamine is (70-75): (10-12): (20-22).

2. A method for preparing a high temperature resistant TPU hot melt adhesive according to claim 1, It is characterized in that The amount of the filler is 10-15% of the mass of the polyester polyol; The filler is monodisperse boehmite; and the particle size distribution range of the monodisperse boehmite is 10-20 μm.

3. A method for preparing a high temperature resistant TPU hot melt adhesive according to claim 2, It is characterized in that The preparation steps of the monodisperse boehmite include: The boehmite and water are mixed, dispersed by ultrasonication, and then a silane coupling agent of 8-10% of the mass of the boehmite is added. After heating and stirring for reaction, the mixture is spray-dried and sieved to obtain the monodisperse boehmite.

4. A method for preparing a high temperature resistant TPU hot melt adhesive according to claim 3, It is characterized in that The silane coupling agent is selected from any one of silane coupling agent KH-540, silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570 and silane coupling agent KH-580.

5. A method for preparing a high temperature resistant TPU hot melt adhesive according to claim 1, It is characterized in that The polyester polyol is selected from any one of poly(1,4-butylene adipate), poly(1,6-hexane adipate) and poly(diethylene adipate).

6. A method for preparing a high temperature resistant TPU hot melt adhesive according to claim 1, It is characterized in that The defoamer is selected from any one of BYK-141, BYK-065, BYK-066, BYK-051 and BYK-052; Furthermore, the defoaming agent is used in an amount of 0.12-0.20% of the mass of the polyester polyol; The antioxidant is selected from any one of antioxidant V-900, antioxidant V-902, and antioxidant V-800; Furthermore, the amount of the antioxidant is 0.04-0.06% of the mass of the polyester polyol; The anti-hydrolysis agent is selected from any one of N,N'-diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, dicyclohexylcarbodiimide, and N,N'-tetramethylbenzene bis[2,6-bis(1-methylethyl)aniline]; Furthermore, the dosage of the anti-hydrolysis agent is 0.03-0.05% of the mass of the polyester polyol.

7. A high temperature resistant TPU hot melt adhesive, It is characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 6.