High-temperature-resistant thermoplastic polyurethane adhesive film and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant thermoplastic polyurethane adhesive film and a preparation method thereof. According to the adhesive film, through a specific raw material formula and a preparation process, the high temperature resistance of the thermoplastic polyurethane adhesive film is remarkably improved, and meanwhile, the comprehensive performance such as good flexibility and cohesiveness is kept. The preparation method disclosed by the invention is simple to operate and easy for industrial production, and the heat-resistant modifier containing the benzotriazole structure is added, so that a stable structure can be formed at high temperature, and the high-temperature resistance of the thermoplastic polyurethane adhesive film is effectively improved. Tests show that the adhesive film can still keep good shape and performance after being heated at 150 DEG C for a long time, the thermal deformation temperature is remarkably improved, and good flexibility, cohesiveness and mechanical performance are kept while the high temperature resistance is improved. The elongation at break can reach 500% or above, and the adhesive has good adhesion to various materials, and can meet the use requirements in different fields.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of high-molecular materials, in particular to a high-temperature-resistant thermoplastic polyurethane adhesive film and a preparation method thereof. BACKGROUND

[0002] The thermoplastic polyurethane is a linear high-molecular material prepared through step-by-step polymerization reaction of diisocyanate, polyol and chain extender. Since the molecular chain contains urethane groups, the thermoplastic polyurethane has good physical and chemical properties. However, under high-temperature conditions, the urethane groups are prone to decomposition reaction, resulting in the performance decline of the adhesive film.

[0003] At present, the methods for improving the high-temperature resistance of the thermoplastic polyurethane mainly include the following: 1. adding heat-resistant additives such as inorganic fillers and flame retardants, but the addition of a large amount of these additives will affect the flexibility and adhesion of the adhesive film; 2. using special diisocyanate or polyol monomers, but these monomers are usually expensive, increasing the production cost; 3. chemically modifying the thermoplastic polyurethane, such as introducing heat-resistant groups, but the modification process is complex and difficult to realize industrial production. Therefore, we propose a method which can effectively improve the high-temperature resistance of the thermoplastic polyurethane adhesive film while maintaining its good comprehensive performance, and the preparation process is simple and the cost is low. Therefore, we propose a high-temperature-resistant thermoplastic polyurethane adhesive film and a preparation method thereof. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a high-temperature-resistant thermoplastic polyurethane adhesive film and a preparation method thereof, which solve the problems raised in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a high-temperature-resistant thermoplastic polyurethane adhesive film, the raw materials of which include the following components in parts by weight: polyester polyol: 30-50 parts; diisocyanate: 20-40 parts; chain extender: 5-15 parts; heat-resistant modifier: 3-10 parts; catalyst: 0.01-0.1 parts; antioxidant: 0.1-1 parts; light stabilizer: 0.1-1 parts.

[0006] Preferably, the polyester polyol is a polyester polyol with a number average molecular weight of 1000-3000.

[0007] Preferably, the diisocyanate is one of toluene diisocyanate, diphenylmethane diisocyanate or hexamethylene diisocyanate.

[0008] Preferably, the chain extender is one of 1,4-butanediol or ethylenediamine.

[0009] Preferably, the heat-resistant modifier is an organic compound containing a benzotriazole structure.

[0010] Preferably, the catalyst is dibutyltin dilaurate.

[0011] Preferably, the antioxidant is a hindered phenolic antioxidant, and the light stabilizer is a hindered amine light stabilizer.

[0012] The raw materials include the following components by weight fraction: Polyester polyol: 30-50 parts; diisocyanate: 20-40 parts; chain extender: 5-15 parts; heat-resistant modifier: 3-10 parts; catalyst: 0.01-0.1 parts; antioxidant: 0.1-1 parts; light stabilizer: 0.1-1 parts.

[0013] Polyester polyol: A polyester polyol with a number average molecular weight of 1000-3000 is selected, such as polybutylene adipate glycol, polyethylene adipate glycol, etc. The molecular structure and molecular weight of the polyester polyol have an important influence on the performance of the thermoplastic polyurethane, and a suitable molecular weight range can ensure that the adhesive film has good flexibility and mechanical properties.

[0014] Diisocyanate: Toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), etc. can be selected. Diisocyanate is an important raw material for forming the polyurethane molecular chain, and different diisocyanates will affect the hardness, heat resistance, and other properties of the polyurethane.

[0015] Chain extender: A small molecule diol or diamine is selected, such as 1,4-butanediol, ethylenediamine, etc. The chain extender can increase the length of the polyurethane molecular chain, improving the strength and hardness of the adhesive film.

[0016] Heat-resistant modifier: It is an organic compound containing a benzotriazole structure, such as 2-(2'-hydroxy-5'-methylphenyl) benzotriazole. This heat-resistant modifier can form a stable structure at high temperatures, improving the high-temperature resistance of the adhesive film, and at the same time has good compatibility with the polyurethane matrix.

[0017] Catalyst: An organometallic catalyst such as dibutyltin dilaurate is selected. The catalyst can accelerate the polymerization reaction and shorten the reaction time.

[0018] Antioxidant: A hindered phenolic antioxidant such as antioxidant 1010 is selected. The antioxidant can prevent the adhesive film from undergoing oxidative degradation in a high-temperature and oxygen environment, extending the service life of the adhesive film.

[0019] Light stabilizer: A hindered amine light stabilizer such as Hostavin W 770 is selected. The light stabilizer can improve the light resistance of the adhesive film and prevent the adhesive film from aging under light.

[0020] The application provides a preparation method of the high-temperature-resistant thermoplastic polyurethane adhesive film. Step 1: raw material pretreatment The polyester polyol is vacuum dehydrated at 100-120 DEG C for 2-4 hours to remove water, so that the water does not react with diisocyanate and affect the polymerization.

[0021] Step 2: prepolymerization The dehydrated polyester polyol is added to a reaction kettle, heated to 60-80 DEG C, then diisocyanate and a catalyst are added, and stirred under nitrogen protection for 2-4 hours to form a polyurethane prepolymer. During the reaction, diisocyanate reacts with polyester polyol to form a prepolymer containing isocyanate end groups.

[0022] Step 3: chain extension The temperature of the reaction kettle is reduced to 40-60 DEG C, the chain extender is added, and the stirring reaction is continued for 1-3 hours to further increase the molecular chain of the prepolymer. After the chain extension reaction is completed, a polyurethane polymer with a certain molecular weight is obtained.

[0023] Step 4: adding additives The heat-resistant modifier, antioxidant and light stabilizer are added to the reaction kettle and stirred uniformly to fully disperse the additives in the polyurethane polymer.

[0024] Step 5: film forming The polyurethane polymer solution obtained by the reaction is made into an adhesive film by a casting method or an extrusion method. The casting method is to uniformly cast the polymer solution on a smooth carrier, and then volatilize the solvent by heating to form an adhesive film. The extrusion method is to extrude the polymer into a film through an extruder.

[0025] Compared with the prior art, the application provides a high-temperature-resistant thermoplastic polyurethane adhesive film and a preparation method thereof, which have the following beneficial effects: 1. The heat-resistant modifier containing a benzotriazole structure is added in the application, which can form a stable structure at high temperature and effectively improve the high-temperature resistance of the thermoplastic polyurethane adhesive film. After long-time heating at 150 DEG C, the adhesive film still maintains good shape and performance, and the heat distortion temperature is significantly improved. 2. The application maintains good flexibility, adhesion and mechanical properties while improving high-temperature resistance. The elongation at break can be more than 500%, and the adhesive film has good adhesion to various materials and can meet the use requirements in different fields. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0027] Secondly, "one embodiment" or "an embodiment" referred to herein means that a specific feature, structure, or characteristic described can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor does it mean that the embodiment is separate or alternative to other embodiments. Embodiment one:

[0028] A high-temperature-resistant thermoplastic polyurethane adhesive film and a preparation method thereof, Raw material formula Polybutylene adipate glycol (number average molecular weight 2000): 40 parts; diphenyl methane diisocyanate (MDI): 30 parts; 1,4-butanediol: 10 parts; 2-(2'-hydroxy-5'-methylphenyl) benzotriazole: 5 parts; dibutyltin dilaurate: 0.05 parts; antioxidant 1010: 0.5 parts; light stabilizer 770: 0.5 parts; Preparation steps Raw material pretreatment: polybutylene adipate glycol was vacuum dehydrated at 110°C for 3 hours.

[0029] Prepolymerization: after dehydration, the polybutylene adipate glycol was added to the reaction kettle, heated to 70°C, and diphenyl methane diisocyanate and dibutyltin dilaurate were added, and stirred under nitrogen protection for 3 hours.

[0030] Chain extension reaction: the temperature of the reaction kettle was reduced to 50°C, 1,4-butanediol was added, and the stirring reaction was continued for 2 hours.

[0031] Addition of additives: 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, antioxidant 1010 and light stabilizer 770 were added to the reaction kettle and stirred uniformly.

[0032] Film formation: the polyurethane polymer solution obtained by reaction was made into an adhesive film by a flow casting method. Embodiment two:

[0033] A high-temperature-resistant thermoplastic polyurethane adhesive film and a preparation method thereof; Raw material formula Polyethylene adipate diol (number average molecular weight 1500): 35 parts; Toluene diisocyanate (TDI): 35 parts; Ethylenediamine: 8 parts; 2-(2'-hydroxy-5'-methylphenyl)benzotriazole: 6 parts; Dibutyltin dilaurate: 0.06 parts; Antioxidant 1010: 0.6 parts; Light stabilizer 770: 0.6 parts; Preparation steps Raw material pretreatment: Polyethylene adipate diol was vacuum dehydrated at 105°C for 3.5 hours.

[0034] Prepolymerization reaction: Dehydrated polyethylene adipate diol was added to a reaction vessel, heated to 75°C, and toluene diisocyanate and dibutyltin dilaurate were added. The mixture was stirred and reacted for 3.5 hours under nitrogen protection.

[0035] Chain extension reaction: Reduce the temperature of the reactor to 55°C, add ethylenediamine, and continue stirring for 1.5 hours.

[0036] Addition of additives: Add 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, antioxidant 1010 and light stabilizer 770 to the reactor and stir until homogeneous.

[0037] Film formation: The polyurethane polymer solution obtained from the reaction is extruded to form a film.

[0038] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0039] Furthermore, in the interest of providing a concise description of illustrative embodiments, not all features of an actual implementation can be described (i.e., those pertaining to the best mode for carrying out the application currently under consideration, or those that, while associated with the application, do not pertain to the best mode for carrying it out).

[0040] Finally, it should be noted that the above-mentioned embodiments are merely used to illustrate the technical solutions of the present application, but not limit the protection scope of the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalent replaced without departing from the spirit and scope of the present application.

Claims

1. A high-temperature resistant thermoplastic polyurethane film, characterized in that, Its raw materials include the following components by weight: polyester polyol: 30-50 parts; Diisocyanate: 20-40 parts; Chain extender: 5-15 parts; heat-resistant modifier: 3-10 parts; Catalyst: 0.01-0.1 parts; Antioxidant: 0.1-1 parts; Light stabilizer: 0.1-1 part.

2. The high-temperature resistant thermoplastic polyurethane film according to claim 1, characterized in that, The polyester polyol is a polyester polyol with a number average molecular weight of 1000-3000.

3. The high-temperature resistant thermoplastic polyurethane film according to claim 1, characterized in that, The diisocyanate is one of toluene diisocyanate, diphenylmethane diisocyanate, or hexamethylene diisocyanate.

4. The high-temperature resistant thermoplastic polyurethane film according to claim 1, characterized in that, The chain extender is one of 1,4-butanediol or ethylenediamine.

5. The high-temperature resistant thermoplastic polyurethane film according to claim 1, characterized in that, The heat-resistant modifier is an organic compound containing a benzotriazole structure.

6. The high-temperature resistant thermoplastic polyurethane film according to claim 1, characterized in that, The catalyst is dibutyltin dilaurate.

7. The high-temperature resistant thermoplastic polyurethane film according to claim 1, characterized in that, The antioxidant is a hindered phenolic antioxidant, and the light stabilizer is a hindered amine light stabilizer.

8. A method for preparing a high-temperature resistant thermoplastic polyurethane film as described in any one of claims 1-7, characterized in that, Includes the following steps: Its raw materials include the following components by weight: Polyester polyol: 30-50 parts; Diisocyanate: 20-40 parts; Chain extender: 5-15 parts; heat-resistant modifier: 3-10 parts; Catalyst: 0.01-0.1 parts; Antioxidant: 0.1-1 parts; Light stabilizer: 0.1-1 part; Polyester polyols: Polyester polyols with a number-average molecular weight of 1000-3000, such as polybutylene adipate diol and polyethylene adipate diol, are selected. The molecular structure and molecular weight of polyester polyols have a significant impact on the performance of thermoplastic polyurethanes; a suitable molecular weight range can ensure that the film has good flexibility and mechanical properties. Diisocyanate: Toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI) can be selected. Diisocyanates are important raw materials for forming polyurethane molecular chains, and different diisocyanates will affect the hardness, heat resistance, and other properties of polyurethane. Chain extender: Small molecule diols or diamines, such as 1,4-butanediol and ethylenediamine, are selected. Chain extenders can increase the length of polyurethane molecular chains, thereby improving the strength and hardness of the film. Heat-resistant modifier: It is an organic compound containing a benzotriazole structure, such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. This heat-resistant modifier can form a stable structure at high temperatures, improving the high-temperature resistance of the film, while also exhibiting good compatibility with the polyurethane matrix; catalyst: Organometallic catalysts such as dibutyltin dilaurate are selected, which can accelerate the polymerization reaction and shorten the reaction time. Antioxidants: Hindered phenolic antioxidants, such as antioxidant 1010, are selected. Antioxidants can prevent oxidative degradation of the film under high temperature and oxygen conditions, thus extending the service life of the film. Light stabilizers: Hindered amine light stabilizers, such as light stabilizer 770, are selected. Light stabilizers can improve the light resistance of the film and prevent the film from aging under light exposure; The present invention discloses a method for preparing a high-temperature resistant thermoplastic polyurethane film, comprising the following steps: Step 1: Raw material pretreatment The polyester polyol is vacuum dehydrated at 100-120℃ for 2-4 hours to remove the water and prevent the water from reacting with the diisocyanate, which would affect the polymerization reaction. Step 2: Prepolymerization reaction The dehydrated polyester polyol is added to a reactor, heated to 60-80℃, and then diisocyanate and catalyst are added. The mixture is stirred and reacted under nitrogen protection for 2-4 hours to generate a polyurethane prepolymer. During the reaction, the diisocyanate reacts with the polyester polyol to form a prepolymer containing isocyanate end groups. Step 3: Chain extension reaction The reactor temperature was lowered to 40-60℃, a chain extender was added, and the reaction was continued with stirring for 1-3 hours to further extend the molecular chains of the prepolymer. After the chain extension reaction was completed, a polyurethane polymer with a certain molecular weight was obtained. Step 4: Adding additives Add heat-resistant modifier, antioxidant and light stabilizer to the reaction vessel, stir evenly to fully disperse the additives in the polyurethane polymer; Step 5: Film Formation The polyurethane polymer solution obtained from the reaction is made into a film by casting or extrusion. Casting involves uniformly casting the polymer solution onto a smooth carrier, and then evaporating the solvent by heating to form a film; extrusion involves extruding the polymer into a film using an extruder.