Self-sealing adhesive for tires and preparation method of self-sealing adhesive

Abstract

The invention relates to the technical field of adhesives, and discloses a self-sealing adhesive for tires and a preparation method thereof.The self-sealing adhesive is prepared from ethylene propylene diene monomer as a base material and a functional cross-linking agent, an initiator, a plasticizer and a modified reinforcing material as auxiliary materials through banburying and extrusion processes, wherein the functional crosslinking agent contains a disulfide bond-maleimide block alternate connection structure, crosslinking modification of the ethylene propylene diene monomer can be achieved, the ethylene propylene diene monomer is converted into a three-dimensional crosslinked network structure from a straight-chain structure, the structure has high cohesive energy, and therefore higher bonding performance can be shown; a disulfide bond contained in the structure of the functional cross-linking agent can endow a three-dimensional network with self-repairing performance, and an unsaturated alkenyl functional group contained in the surface of the modified reinforcing material can participate in a subsequent cross-linking process, so that kaolin can efficiently exert own advantages, and the strength of a sealant layer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to a self-sealing adhesive for tires and a preparation method thereof. Background Art

[0002] In today's rapidly developing automotive industry, tires, as the only part of a vehicle that comes into direct contact with the ground, are of paramount importance for their safety. Once a tire is punctured by a sharp object, not only can the vehicle not function properly, it can also cause a serious traffic accident. To address this issue, tire self-sealing adhesives have emerged. These self-sealing adhesives are formed by coating the inside of the tire with a layer of self-sealing adhesive. They automatically seal the wound the moment the tire is punctured, preventing air leaks and a rapid drop in tire pressure, allowing the vehicle to continue driving for a certain distance and buying the driver valuable time to resolve the issue.

[0003] At present, self-sealing adhesives for tires are generally divided into hot melt adhesive systems and rubber systems. The hot melt adhesive system is relatively simple in formulation and process, but the disadvantage of the hot melt adhesive system is that it requires high-temperature spraying. This spraying method is difficult to achieve a uniform coating effect inside a tire with an arc structure, resulting in uneven thickness of the self-sealing adhesive layer, making it difficult to form effective protection. Compared with the hot melt adhesive system, the rubber system has a simpler coating process, but the problem with the rubber system is that it has a low degree of cross-linking, poor high-temperature dimensional stability, and no self-repair effect. Once the tire is repeatedly punctured in the same area, there is still a high risk of accidents. Based on this, the present invention provides a self-sealing adhesive that can be directly used on tires to solve the problems existing in the prior art. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In view of the deficiencies in the prior art, the present invention provides a self-sealing adhesive for tires and a preparation method thereof.

[0006] (2) Technical solution

[0007] A self-sealing adhesive for tires, comprising the following raw materials in parts by weight:

[0008] 70-85 parts of EPDM rubber, 2-5 parts of functional crosslinking agent, 0.3-0.5 parts of initiator, 10-20 parts of plasticizer, 5-10 parts of modified reinforcing material;

[0009] The modified reinforcing material is kaolin with unsaturated olefinic functional groups modified on the surface.

[0010] As a further embodiment of the present invention, the preparation method of the functional cross-linking agent comprises the following steps:

[0011] Step 1: Prepare intermediate material

[0012] Nitrogen is introduced into the reactor and air is exhausted. 3-maleimidopropionic acid and acetone are then added to the reactor and stirred to mix evenly. The composite catalyst is then added to the reactor and stirred at 30-40° C. for 1-2 hours. 1,3-diglycidyl ether glycerol is then added to the reactor and stirred at room temperature for 3-6 hours. The solvent is evaporated and the product is collected to obtain an intermediate material.

[0013] Step 2: Preparation of functional cross-linking agent

[0014] Add the intermediate material, 3,3'-dithiodipropionic acid and N,N-dimethylformamide to a polymerization kettle filled with nitrogen. After the addition is completed, start stirring until a uniform solution is formed. Then add the phase transfer catalyst to the polymerization kettle. After the addition is completed, start heating and control the temperature at 70-80°C. After continuous stirring and insulation for 12-18 hours, stop heating, cool and discharge the material to obtain a functional crosslinking agent.

[0015] As a further embodiment of the present invention, in step 1, the molar ratio of 3-maleimidopropionic acid to 1,3-diglycidyl ether glycerol is 1:1.

[0016] As a further embodiment of the present invention, in step 1, the composite catalyst is a mixture of N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, with a mass ratio of 0.3-0.4:1.

[0017] As a further embodiment of the present invention, in step 2, the molar ratio of the intermediate material to 3,3'-dithiodipropionic acid is 1:0.8-1.

[0018] As a further embodiment of the present invention, in step 2, the phase transfer catalyst is any one of tetrabutylammonium hydrogen sulfate, tetramethylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride or N,N-dimethylbenzylamine.

[0019] In the above technical solution, 3-maleimidopropionic acid and 1,3-diepoxyglycerol ether glycerol are first used as reactants. Under the catalytic action of a composite catalyst, the active carboxyl substituents and hydroxyl substituents in each other's structures can undergo an esterification condensation reaction at room temperature to obtain a maleimide derivative containing two equivalents of epoxy substituents in the structure, i.e., an intermediate material. Then, under the action of a phase transfer catalyst, 3,3'-dithiodipropionic acid is used as a chain extender to undergo a continuous ring-opening esterification reaction with the epoxy substituents in the intermediate material structure to obtain a macromolecular functional cross-linking agent connected by ester bonds and having a disulfide bond-maleimide block alternating connection structure.

[0020] As a further embodiment of the present invention, the initiator is benzoyl peroxide or dicumyl peroxide; and the plasticizer is at least one of polyisoprene, polybutadiene, polybutylene or styrene-butadiene copolymer.

[0021] As a further embodiment of the present invention, the preparation method of the modified reinforcing material is as follows:

[0022] The kaolin is ultrasonically dispersed in toluene to form a uniform dispersion, and then a functionalizing agent and an organic tin catalyst are added to the dispersion. After the addition is completed, the temperature is raised to 80-90°C, and the mixture is kept warm and stirred for 6-9 hours. The mixture is then cooled and discharged. After a post-processing purification process, the modified reinforcing material can be obtained.

[0023] As a further embodiment of the present invention, the functionalizing agent is any one of ethyl isocyanate acrylate, isocyanoethyl methacrylate or 3-isopropyl-dimethylbenzyl isocyanate; and the organotin catalyst is any one of dibutyltin dilaurate, dioctyltin dilaurate, methyl tin mercaptan or octyl tin mercaptan.

[0024] In the above technical solution, under the action of an organic tin catalyst, the isocyanate group in the functionalizing agent structure can undergo an amine esterification reaction with the hydroxyl group on the surface of kaolin, thereby modifying the unsaturated olefinic functional group in the functionalizing agent on the surface of kaolin to prepare a modified reinforcing material.

[0025] A method for preparing a self-sealing adhesive for a tire comprises the following steps:

[0026] The first step is to weigh each raw material according to the weight and set aside;

[0027] Step 2: Add EPDM rubber, functional cross-linking agent, initiator and modified reinforcing material into an internal mixer and mix them to form a mixture;

[0028] The third step is to add plasticizer to the mixture, mix it evenly, and then feed it into a twin-screw extruder for melt extrusion.

[0029] (3) Beneficial technical effects

[0030] The present invention prepares a macromolecular functional crosslinker containing an alternating disulfide-maleimide block structure as a crosslinker for EPDM rubber. During the subsequent melt extrusion process, the presence of the functional crosslinker can achieve crosslinking modification of the EPDM rubber, transforming it from a linear structure into a three-dimensional crosslinked network. This structure has higher cohesive energy and therefore exhibits higher adhesion properties. Furthermore, because the functional crosslinker structure contains a large number of hydroxyl functional groups generated by the ring-opening esterification reaction, these hydroxyl functional groups can form more hydrogen bonding sites with the tire, further improving the sealant's adhesion and enabling it to better adhere to the inside of the tire. Furthermore, the disulfide bonds in the functional crosslinker structure can impart self-healing properties to the three-dimensional network. After a tire puncture, the self-sealing sealant can be self-repaired by heating, preventing repeated punctures in the same area, which would significantly increase the risk of accidents.

[0031] The present invention prepares kaolin with unsaturated olefinic functional groups on its surface as a modified reinforcing material. Since the unsaturated olefinic functional groups can participate in the subsequent cross-linking process, the interface problem between the kaolin and the EPDM rubber can be effectively improved, and the kaolin exists in the cross-linking network in the form of a cross-linking core, effectively exerting its advantages and improving the puncture resistance of the sealant layer. DETAILED DESCRIPTION

[0032] To facilitate understanding of the present invention, the present invention will be described in more detail below. Preferred embodiments of the present invention are provided below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0033] Example 1

[0034] A self-sealing adhesive for tires, comprising the following raw materials in parts by weight:

[0035] 70 parts of EPDM rubber, 2 parts of functional crosslinking agent, 0.3 parts of benzoyl peroxide, 10 parts of polyisoprene, and 5 parts of modified reinforcing material;

[0036] The preparation method of the self-sealing adhesive comprises the following steps:

[0037] The first step is to weigh each raw material according to the weight and set aside;

[0038] Step 2: adding EPDM rubber, functional cross-linking agent, benzoyl peroxide and modified reinforcing material into an internal mixer and mixing to form a mixture;

[0039] The third step is to add polyisoprene to the mixture, mix it evenly, and then feed it into a twin-screw extruder. Set the temperature of the three zones to 150°C and the screw aspect ratio to 60 for melt extrusion.

[0040] The preparation method of the functional cross-linking agent comprises the following steps:

[0041] Step 1: Prepare intermediate material

[0042] Nitrogen was introduced into the reactor and the air was exhausted. Then, 0.4 g of 3-maleimidopropionic acid and acetone were added to the reactor and stirred to mix evenly. Then, 0.1 g of N-hydroxysuccinimide and 0.3 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride were added to the reactor. After the addition was complete, the mixture was stirred at 40° C. for 1 h. 0.48 g of 1,3-diglycidyl ether glycerol was added to the reactor. After the addition was complete, the mixture was stirred at room temperature for 4 h. The solvent was evaporated and the product was collected to obtain an intermediate material.

[0043] Step 2: Preparation of functional cross-linking agent

[0044] Add 0.8 g of the intermediate material, 0.4 g of 3,3'-dithiodipropionic acid and N,N-dimethylformamide to a polymerization kettle filled with nitrogen. After the addition is completed, start stirring until a uniform solution is formed. Then, add 0.01 g of tetrabutylammonium bromide to the polymerization kettle. After the addition is completed, start heating and control the temperature at 75°C. After continuous stirring and insulation for 16 hours, stop heating, cool and discharge the material to obtain a functional crosslinking agent.

[0045] The preparation method of the modified reinforcing material is as follows:

[0046] 1.5 g of kaolin was ultrasonically dispersed in toluene to form a uniform dispersion. Then, 0.4 g of ethyl cyanate acrylate and 0.01 g of dibutyltin dilaurate were added to the dispersion. After the addition, the temperature was raised to 85°C, and the mixture was kept warm and stirred for 8 hours. The temperature was then lowered and the material was discharged. After post-processing and purification, the modified reinforcing material was obtained.

[0047] Example 2

[0048] A self-sealing adhesive for tires, comprising the following raw materials in parts by weight:

[0049] 75 parts of EPDM rubber, 4.5 parts of functional crosslinking agent, 0.4 parts of dicumyl peroxide, 15 parts of polybutadiene, and 8.5 parts of modified reinforcing material;

[0050] The preparation method of the self-sealing adhesive comprises the following steps:

[0051] The first step is to weigh each raw material according to the weight and set aside;

[0052] The second step is to add EPDM rubber, functional crosslinking agent, dicumyl peroxide and modified reinforcing material into an internal mixer and mix them to form a mixture;

[0053] The third step is to add polybutadiene to the mixture, mix it evenly, and then feed it into a twin-screw extruder. Set the temperature of the three zones to 150°C and the screw aspect ratio to 60 for melt extrusion.

[0054] The preparation method of the functional cross-linking agent and the modified reinforcing material is the same as that in Example 1.

[0055] Example 3

[0056] A self-sealing adhesive for tires, comprising the following raw materials in parts by weight:

[0057] 85 parts of EPDM rubber, 5 parts of functional crosslinking agent, 0.5 parts of dicumyl peroxide, 20 parts of polyisoprene, and 10 parts of modified reinforcing material;

[0058] The preparation method of the self-sealing adhesive comprises the following steps:

[0059] The first step is to weigh each raw material according to the weight and set aside;

[0060] The second step is to add EPDM rubber, functional crosslinking agent, dicumyl peroxide and modified reinforcing material into an internal mixer and mix them to form a mixture;

[0061] The third step is to add polyisoprene to the mixture, mix it evenly, and then feed it into a twin-screw extruder. Set the temperature of the three zones to 150°C and the screw aspect ratio to 60 for melt extrusion.

[0062] The preparation method of the functional cross-linking agent and the modified reinforcing material is the same as that in Example 1.

[0063] Comparative Example 1

[0064] A self-sealing adhesive for tires, comprising the following raw materials in parts by weight:

[0065] 75 parts of EPDM rubber, 4.5 parts of functional crosslinking agent, 0.4 parts of dicumyl peroxide, 15 parts of polybutadiene, and 8.5 parts of kaolin;

[0066] The preparation method of the self-sealing adhesive comprises the following steps:

[0067] The first step is to weigh each raw material according to the weight and set aside;

[0068] The second step is to add EPDM rubber, functional crosslinking agent, dicumyl peroxide and kaolin into an internal mixer and mix them to form a mixture;

[0069] The third step is to add polybutadiene to the mixture, mix it evenly, and then feed it into a twin-screw extruder. Set the temperature of the three zones to 150°C and the screw aspect ratio to 60 for melt extrusion.

[0070] The preparation method of the functional cross-linking agent is the same as that in Example 1.

[0071] Comparative Example 2

[0072] A self-sealing adhesive for tires, comprising the following raw materials in parts by weight:

[0073] 75 parts of EPDM rubber, 4.5 parts of functional crosslinking agent, 0.4 parts of dicumyl peroxide, and 15 parts of polybutadiene;

[0074] The preparation method of the self-sealing adhesive comprises the following steps:

[0075] The first step is to weigh each raw material according to the weight and set aside;

[0076] Step 2: adding EPDM rubber, functional crosslinking agent and dicumyl peroxide into an internal mixer and mixing to form a mixture;

[0077] The third step is to add polybutadiene to the mixture, mix it evenly, and then feed it into a twin-screw extruder. Set the temperature of the three zones to 150°C and the screw aspect ratio to 60 for melt extrusion.

[0078] The preparation method of the functional cross-linking agent is the same as that in Example 1.

[0079] Comparative Example 3

[0080] A self-sealing adhesive for tires, comprising the following raw materials in parts by weight:

[0081] 75 parts of EPDM rubber, 0.4 parts of dicumyl peroxide, 15 parts of polybutadiene, and 8.5 parts of modified reinforcing material;

[0082] The preparation method of the self-sealing adhesive comprises the following steps:

[0083] The first step is to weigh each raw material according to the weight and set aside;

[0084] Step 2: Add EPDM rubber, dicumyl peroxide and modified reinforcing material into an internal mixer and mix them to form a mixture;

[0085] The third step is to add polybutadiene to the mixture, mix it evenly, and then feed it into a twin-screw extruder. Set the temperature of the three zones to 150°C and the screw aspect ratio to 60 for melt extrusion.

[0086] The preparation method of the modified reinforcing material is the same as that of Example 1.

[0087] Performance Testing

[0088] The self-sealing adhesives prepared in the examples and comparative examples were made into various film test samples that met the specifications, and various performance tests were performed. The results are recorded in Table 1:

[0089] Table 1 - Test results

[0090] 180° peel strength (N / 25mm) Puncture resistance (N / mm) Self-repair rate (%) Example 1 6.8 259 100 Example 2 7.1 265 100 Example 3 7.0 263 100 Comparative Example 1 6.5 218 100 Comparative Example 2 6.6 178 100 Comparative Example 3 5.5 241 20

[0091] The 180° peel strength is tested according to the standard GB / T 2792-2014; the puncture resistance is tested according to the standard GB / T37841-2019; the self-repair rate test method is as follows: use a scraper to scrape a 5mm deep dent on the surface of a 1cm thick film sample, then place the film sample in a temperature environment of 80℃, take it out after 4 hours, measure the dent depth, and calculate the repair rate.

[0092] According to the test results, it can be analyzed that the self-sealing adhesive prepared in the embodiment of the present invention has good bonding performance, puncture resistance and self-repair effect.

[0093] After the modified reinforcing material is replaced with kaolin that has not been surface-modified, due to interface problems, the kaolin cannot effectively exert its own reinforcing effect, and the puncture resistance is greatly reduced.

[0094] After the functional cross-linking agent is removed, the self-sealing adhesive cannot form a cross-linking structure, and the structure does not contain disulfide bonds, so it cannot produce a self-repairing effect.

[0095] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0096] Based on the ideal embodiments of the present invention, and with reference to the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A self-sealing adhesive for tires, characterized in that: According to parts by weight, the following raw materials are included: 70-85 parts of EPDM rubber, 2-5 parts of functional crosslinking agent, 0.3-0.5 parts of initiator, 10-20 parts of plasticizer, 5-10 parts of modified reinforcing material; The modified reinforcing material is kaolin with unsaturated olefinic functional groups modified on the surface.

2. The tire self-sealing adhesive according to claim 1, characterized in that: The preparation method of the functional cross-linking agent comprises the following steps: Step 1: Prepare intermediate material Nitrogen is introduced into the reactor and air is exhausted. 3-maleimidopropionic acid and acetone are then added to the reactor and stirred to mix evenly. The composite catalyst is then added to the reactor and stirred at 30-40° C. for 1-2 hours. 1,3-diglycidyl ether glycerol is then added to the reactor and stirred at room temperature for 3-6 hours. The solvent is evaporated and the product is collected to obtain an intermediate material. Step 2: Preparation of functional cross-linking agent Add the intermediate material, 3,3'-dithiodipropionic acid and N,N-dimethylformamide to a polymerization kettle filled with nitrogen. After the addition is completed, start stirring until a uniform solution is formed. Then add the phase transfer catalyst to the polymerization kettle. After the addition is completed, start heating and control the temperature at 70-80°C. After continuous stirring and insulation for 12-18 hours, stop heating, cool and discharge the material to obtain a functional crosslinking agent.

3. The self-sealing adhesive for tire according to claim 2, characterized in that: In step 1, the molar ratio of the 3-maleimidopropionic acid to the 1,3-diglycidyl ether glycerol is 1:

1.

4. The tire self-sealing adhesive according to claim 2, characterized in that: In step 1, the composite catalyst is a mixture of N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, with a mass ratio of 0.3-0.4:

1.

5. The self-sealing adhesive for tire according to claim 2, characterized in that: In step 2, the molar ratio of the intermediate material to 3,3'-dithiodipropionic acid is 1:0.8-1.

6. The self-sealing adhesive for tire according to claim 2, characterized in that: In step 2, the phase transfer catalyst is any one of tetrabutylammonium hydrogen sulfate, tetramethylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride or N,N-dimethylbenzylamine.

7. The self-sealing adhesive for tire according to claim 1, characterized in that: The initiator is benzoyl peroxide or dicumyl peroxide; the plasticizer is at least one of polyisoprene, polybutadiene, polybutylene or styrene-butadiene copolymer.

8. The self-sealing adhesive for tires according to claim 1, characterized in that: The preparation method of the modified reinforcing material is as follows: The kaolin is ultrasonically dispersed in toluene to form a uniform dispersion, and then a functionalizing agent and an organic tin catalyst are added to the dispersion. After the addition is completed, the temperature is raised to 80-90°C, and the mixture is kept warm and stirred for 6-9 hours. The mixture is then cooled and discharged. After a post-processing purification process, the modified reinforcing material can be obtained.

9. The self-sealing adhesive for tires according to claim 8, characterized in that: The functionalizing agent is any one of ethyl isocyanate acrylate, isocyanoethyl methacrylate or 3-isopropyl-dimethylbenzyl isocyanate; the organotin catalyst is any one of dibutyltin dilaurate, dioctyltin dilaurate, methyl tin mercaptan or octyl tin mercaptan.

10. A method for preparing the self-sealing adhesive for tires according to claim 1, characterized in that: The following steps are involved: The first step is to weigh each raw material according to the weight and set aside; Step 2: Add EPDM rubber, functional cross-linking agent, initiator and modified reinforcing material into an internal mixer and mix them to form a mixture; The third step is to add plasticizer to the mixture, mix it evenly, and then feed it into a twin-screw extruder for melt extrusion.