Adhesive film suitable for compounding of automotive interiors and preparation method of adhesive film

Abstract

The invention discloses an adhesive film suitable for automobile interior compounding and a preparation method of the adhesive film, and particularly relates to the technical field of automobile interior materials, the preparation method comprises the following steps: blocking an isocyanate group of polyurethane to prepare a blocked polyurethane prepolymer; adding a reaction type end-capping reagent and a catalyst to obtain an aliphatic polyurethane adhesive; preparing the aliphatic polyurethane adhesive into a polyurethane adhesive film; the polyurethane adhesive film is heated, activated and unsealed, the unsealed polyurethane prepolymer and the reactive groups are subjected to a curing reaction, the bonding characteristic is rapidly achieved, and the interior materials are bonded. According to the method disclosed by the invention, the polyurethane adhesive film is endowed with the characteristics of low-temperature activity, rapid curing and the like, can be activated and rapidly bonded at a relatively low temperature, avoids the problem that thermal deformation of a base material is easily caused at a high temperature, has excellent environment-friendly properties of hydrolysis resistance, yellowing resistance, solvent resistance, low emission and the like, and has good bonding strength, heat resistance and flexibility; and various use requirements of the automotive trim composite material are met.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile interior materials, and more particularly to an adhesive film suitable for automobile interior composites and a preparation method thereof. Background Art

[0002] The composite process for automotive interior materials typically utilizes solvent-based or hot-melt adhesives. While simple to operate, solvent-based adhesives pose safety risks, including significant environmental pollution, adverse health effects for workers, and flammability and explosiveness. They are also costly, energy-intensive, and prone to excessive solvent residue. While hot-melt adhesives are solvent-free, traditional thermoplastic hot-melt adhesives exhibit low bond strength and poor heat resistance. While reactive polyurethane hot-melt adhesives offer excellent overall performance, they suffer from drawbacks such as high application temperatures that can easily cause thermal deformation of the bonded material, demanding storage conditions, and long post-curing times.

[0003] Automotive interior materials place stringent demands on adhesives, requiring them to possess environmentally friendly properties such as excellent hydrolysis resistance, yellowing resistance, solvent resistance, and low emissions. They must also possess excellent performance characteristics such as bonding strength, heat resistance, and flexibility. Existing technologies struggle to simultaneously meet all of these performance requirements.

[0004] Chinese Patent Publication No. CN118222234A discloses an aliphatic polyurethane adhesive that is resistant to UV aging and yellowing, and its preparation method. The polyurethane adhesive produced in this patent exhibits rapid curing at room temperature and humidity, maintains high mechanical properties for long periods of time even under intense UV irradiation, and exhibits excellent resistance to yellowing. However, this patent still faces challenges in optimizing the formulation and process parameters to improve the adhesive's UV aging and yellowing resistance.

[0005] Chinese Patent Publication No. CN113249081A discloses a polyurethane film and its preparation method. Through the screening and compounding of components, this polyurethane film exhibits high tensile strength, high elongation at break, and high light transmittance, demonstrating excellent mechanical strength, flexibility, optical properties, and yellowing resistance, making it suitable as an interlayer material for laminated glass. However, this patent still faces the challenge of further optimizing the ratio of polyether polyol and diisocyanate to improve the film's mechanical and optical properties.

[0006] Therefore, it is of great significance to develop a new type of film material suitable for automotive interior composites. Summary of the Invention

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention provides an adhesive film suitable for automotive interior composite and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions: In the first aspect, the present application provides a composite adhesive film suitable for automotive interiors, which adopts the following technical solutions: A composite adhesive film suitable for automotive interiors, the raw materials for its preparation include the following components in parts by weight: 40-50 parts of 4,4-dicyclohexylmethane diisocyanate, 35-50 parts of polyol, 25-40 parts of polyester diol, 1-3 parts of chain extender, 1-3 parts of prepolymer catalyst, 15-20 parts of end-capping agent and 1-3 parts of composite catalyst.

[0009] Furthermore, the polyol includes at least one or more of trifunctional polyether polyol with a molecular weight of 5000, polypropylene glycol with a molecular weight of 1000, and polyethylene glycol with a molecular weight of 6000; The polyester diol includes at least one or more of polyneopentyl adipate diol with a molecular weight of 2000 and polybutylene succinate diol with a molecular weight of 2000; The chain extender includes at least one or more of diethylene glycol and diethylene glycol; The prepolymer catalyst includes at least one or more of dibutyltin dilaurate and bis(octyltin).

[0010] Furthermore, the end-capping agent includes at least one or more of acetyl tributyl citrate and acetylacetone semiol; The composite catalyst comprises at least one or more of dibutyltin dilaurate, bismorpholine diethyl ether, bis(2-ethylhexyl)tin salt, and tri(di-n-butyl)tin oxide.

[0011] Furthermore, the invention further comprises 1-3 parts of a light stabilizer and 1-3 parts of an antioxidant, wherein the light stabilizer is bis(1,2,2,6,6-pentamethylpiperidinol) sebacate, and the antioxidant is isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

[0012] In a second aspect, the present application provides a method for preparing a composite adhesive film for automotive interiors, using the following technical solution: A method for preparing a composite adhesive film for automotive interiors comprises the following steps: Step 1: preparing 4,4-dicyclohexylmethane diisocyanate, polyol, polyester diol, chain extender, prepolymer catalyst, end-capping agent and composite catalyst as raw materials; Step 2: Under nitrogen protection, add 4,4-dicyclohexylmethane diisocyanate to a reactor, raise the temperature to 75-80°C, add polyol, polyester diol, chain extender and prepolymer catalyst, and react at a constant temperature for 2-4 hours. After the NCO% of the reactant reaches the theoretical value, stop the reaction and cool to 40-60°C to prepare a blocked polyurethane prepolymer; Step 3: adding a blocking agent and a composite catalyst to the system of the prepared blocked polyurethane prepolymer, stirring, discharging and sealing for storage to prepare an aliphatic polyurethane adhesive; Step 4: preparing the prepared aliphatic polyurethane adhesive into a polyurethane film by roller coating, transfer, casting or calendaring; Step 5: Heat the prepared polyurethane film until its temperature reaches the melting point and then activate and unblock it, exposing the isocyanate groups; allow the unblocked polyurethane prepolymer to mature and react with the reactive groups in the system to quickly achieve bonding properties and bond the interior materials.

[0013] Furthermore, the specific steps of step 2 are: under nitrogen protection, adding isocyanate to the reactor, heating to 75-80°C, adding polyol, chain extender and prepolymer catalyst, reacting at a constant temperature for 2-3 hours, and stopping the reaction after the NCO% of the test reactant reaches the theoretical value and cooling to 40-60°C.

[0014] Furthermore, the specific steps of step 2 are: under nitrogen protection, adding 4,4-dicyclohexylmethane diisocyanate to a reactor, heating to 75-80°C, adding a trifunctional high-activity polyether polyol with a molecular weight of 5000, polyneopentyl adipate diol with a molecular weight of 2000, diethylene glycol and dibutyltin dilaurate, reacting at a constant temperature for 2-3 hours, and stopping the reaction after the NCO% of the test reactant is close to the theoretical value and cooling to 50°C.

[0015] Furthermore, the specific steps of step 2 are: under nitrogen protection, 4,4-dicyclohexylmethane diisocyanate is added to the reactor, the temperature is raised to 70-85°C, poly (neopentyl adipate glycol) with a molecular weight of 2000, polypropylene glycol with a molecular weight of 1000, diethylene glycol and dioctyl tin are reacted at a constant temperature for 2-4 hours, and the reaction is stopped after the NCO% of the test reactants reaches the theoretical value and the temperature is lowered to 45-55°C.

[0016] Furthermore, the specific steps of step 2 are: under nitrogen protection, 4,4-dicyclohexylmethane diisocyanate is added to the reactor, the temperature is raised to 75-83 ° C, polyethylene glycol with a molecular weight of 6000, polybutylene succinate diol with a molecular weight of 2000, diethylene glycol and dioctyl tin are added, and the reaction is carried out at a constant temperature for 2.5-3.5 hours. After the NCO% of the test reactant reaches the theoretical value, the reaction is stopped and the temperature is lowered to 48-58 ° C.

[0017] Furthermore, the specific steps of step 3 are: adding a reactive end-capping agent and a catalyst into the system, stirring for 20-40 minutes, then discharging the material and sealing and storing it to obtain an aliphatic polyurethane adhesive.

[0018] Furthermore, the specific steps of step 3 are: adding acetyl tributyl citrate, bis(1,2,2,6,6-pentamethylpiperidinol) sebacate, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, dibutyltin dilaurate and bismorpholine diethyl ether into the system, stirring for 30 minutes, then discharging and sealing for storage to obtain an aliphatic polyurethane adhesive.

[0019] Furthermore, the specific steps of step 3 are: adding acetylacetone semi-alcohol, bis(2-ethylhexyl)tin salt, tri(di-n-butyl)tin oxide and bismorpholine diethyl ether into the system, stirring for 20-40 minutes, then discharging and sealing for storage to obtain an aliphatic polyurethane adhesive.

[0020] Furthermore, the specific steps of step 3 are: adding acetylacetone semi-alcohol, bis(2-ethylhexyl)tin salt, tri(di-n-butyl)tin oxide and bismorpholine diethyl ether into the system, stirring for 25-35 minutes, then discharging and sealing for storage to obtain an aliphatic polyurethane adhesive.

[0021] In summary, this application has the following beneficial effects: The preparation method of the present invention gives the polyurethane film the characteristics of low-temperature activity and rapid curing. It can be activated at a relatively low temperature and quickly achieve bonding, avoiding the problem of thermal deformation of the substrate easily caused by high temperature. At the same time, it has excellent environmental protection properties such as hydrolysis resistance, yellowing resistance, solvent resistance, and low emission, as well as good bonding strength, heat resistance and softness, meeting various use requirements of automotive interior composite materials. DETAILED DESCRIPTION

[0022] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0023] Example 1 A composite adhesive film suitable for automotive interiors is prepared by the following steps: Step 1: 30 parts of polyneopentyl adipate diol with a molecular weight of 2000, 50 parts of trifunctional high-activity polyether polyol with a molecular weight of 5000, and 40 parts of 4,4-dicyclohexylmethane diisocyanate are selected as the main raw materials of polyurethane; 20 parts of acetyl tributyl citrate are selected as a reactive end-capping agent with low-temperature activity.

[0024] Step 2: Under nitrogen protection, add 4,4-dicyclohexylmethane diisocyanate to the reactor, raise the temperature to 75°C, add a trifunctional high-activity polyether polyol with a molecular weight of 5000, polyneopentyl adipate diol with a molecular weight of 2000, 2 parts of diethylene glycol and 2 parts of dibutyltin dilaurate as a prepolymer catalyst, react at a constant temperature for 2 hours, and stop the reaction when the NCO% of the reactant is close to the theoretical value and cool to about 40°C.

[0025] Step 3: Add acetyl tributyl citrate, 1 part of bis(1,2,2,6,6-pentamethylpiperidinol) sebacate, 1 part of isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1 part of dibutyltin dilaurate, and 1 part of a composite catalyst of bismorpholine diethyl ether to the system, stir for 30 minutes, then discharge the material and seal for storage to obtain an aliphatic polyurethane adhesive.

[0026] Step 4: prepare the aliphatic polyurethane adhesive into a polyurethane film by roll coating, transfer, casting or calendaring.

[0027] Step 5: Heat the polyurethane film to 55°C until it reaches its melting point, deblocking it and exposing the isocyanate groups. The deblocked polyurethane prepolymer reacts with the hydroxyl and other reactive groups in the system to quickly achieve bonding properties, allowing interior materials to be bonded.

[0028] Example 2 A composite adhesive film suitable for automotive interiors is prepared by the following steps: Step 1: Select 40 parts of polypropylene glycol with a molecular weight of 1000, 35 parts of polyneopentyl adipate glycol with a molecular weight of 2000, and 45 parts of 4,4-dicyclohexylmethane diisocyanate as main raw materials of polyurethane; select 15 parts of acetylacetone semiol as a reactive end-capping agent with low-temperature activity.

[0029] Step 2: Under nitrogen protection, add 4,4-dicyclohexylmethane diisocyanate to the reactor, raise the temperature to 80°C, add poly (neopentyl adipate glycol) with a molecular weight of 2000, poly (propylene glycol) with a molecular weight of 1000, 1 part of diethylene glycol and 1 part of dioctyl tin prepolymer catalyst, react at a constant temperature for 2-4 hours, and stop the reaction when the NCO% of the test reactant is close to the theoretical value and cool to 60°C. Step 3: Add a composite catalyst of acetylacetone semi-ol, 1 part of bis(2-ethylhexyl)tin salt, 1 part of tri(di-n-butyl)tin oxide and 1 part of bismorpholine diethyl ether to the system, stir for 20-40 minutes, then discharge and seal for storage to obtain an aliphatic polyurethane adhesive.

[0030] Step 4: prepare the aliphatic polyurethane adhesive into a polyurethane film by roll coating, transfer, casting or calendaring.

[0031] Step 5: Heat the polyurethane film to 70°C until it reaches its melting point, activating and deblocking it, exposing the isocyanate groups. The deblocked polyurethane prepolymer reacts with the hydroxyl and other reactive groups within the system to quickly achieve bonding properties, allowing interior materials to be bonded.

[0032] Example 3 A composite adhesive film suitable for automotive interiors is prepared by the following steps: Step 1: Select 25 parts of polybutylene succinate diol with a molecular weight of 2000, 45 parts of polyethylene glycol with a molecular weight of 6000, and 50 parts of 4,4-dicyclohexylmethane diisocyanate as the main raw materials of polyurethane; select 18 parts of acetylacetone semiol as a reactive end-capping agent with low-temperature activity. Step 2: Under nitrogen protection, 4,4-dicyclohexylmethane diisocyanate was added to the reactor, the temperature was raised to 78 ° C, polyethylene glycol with a molecular weight of 6000, polybutylene succinate diol with a molecular weight of 2000, 3 parts of diethylene glycol and 3 parts of dioctyl tin prepolymer catalyst were added, and the reaction was carried out at a constant temperature for 3 hours. After the NCO% of the test reactant was close to the theoretical value, the reaction was stopped and the temperature was lowered to 50 ° C.

[0033] Step 3: Add a composite catalyst of acetylacetone semi-ol, 1 part of bis(2-ethylhexyl)tin salt, 1 part of tri(di-n-butyl)tin oxide and 1 part of bismorpholine diethyl ether to the system, stir for 25-35 minutes, then discharge and seal for storage to obtain an aliphatic polyurethane adhesive.

[0034] Step 4: prepare the aliphatic polyurethane adhesive into a polyurethane film by roll coating, transfer, casting or calendaring.

[0035] Step 5: Heat the polyurethane film to 55°C until it reaches its melting point, deblocking it and exposing the isocyanate groups. The deblocked polyurethane prepolymer reacts with the hydroxyl and other reactive groups within the system to quickly achieve bonding properties, allowing interior materials to be bonded.

[0036] Performance testing The performance tests were conducted on the adhesive films suitable for automotive interior composites prepared in Examples 1-3 and a commercially available adhesive film as Comparative Example 1. The commercially available adhesive film in Comparative Example 1 was a spray-free adhesive film produced by Shanghai Xuanliyoupin Environmental Protection Technology Co., Ltd. The following properties were tested. The test methods and results are as follows: Melting point: According to the DSC test method, the exothermic curve was measured in the range of 0 to 180°C using a differential scanning calorimeter.

[0037] Tensile properties: According to DIN EN ISO 1798-2008, the tensile strength and elongation at break properties were tested using an electronic universal testing machine.

[0038] Rheological properties: Use a multi-module accelerating calorimeter to maintain the test condition at 120℃ for 30 minutes, and record the modulus and viscosity data.

[0039] Odor: According to VDA 270-2018 standard, the odor level is evaluated through subjective testing.

[0040] VOC and TVOC: VOC and TVOC content are tested using GC-MS mass spectrometry in accordance with GS 97014-3-2002.

[0041] Humidity and heat aging: 10 cycles are set according to Volkswagen PV1200 (+80℃ to -40℃).

[0042] Color difference: According to the CLAB test standard, record the L, a, b values ​​and calculate the DE value.

[0043] Temperature resistance test: According to the temperature resistance test at 120℃ and 180°, the displacement is measured when a 500g weight is hung on the surface for 30 minutes.

[0044] Peel force: According to GB / T 8808-1988 standard, use a tensile testing machine to test and record the data.

[0045] Test items Example 1 Example 2 Example 3 Commercially available comparative example 1 Melting point 54.24 58.47 60.32 88.92 Rheological properties: 120℃, 0~30min modulus increase pa 5000 8000 6000 1000 Rheological properties: 120℃, viscosity increase in 30min pa.s 1000 1900 1200 200 Tensile strength KPa 26 25 28 38 Odor level 3.5 Plastic smell 3.5 Plastic smell 3.5 Plastic smell 3.5 Plastic smell Formaldehyde μg / m3 56 38 76 122 TVOC μg / m3 2087 1320 1580 5203 Color difference DE is tested after 10 cycles of damp heat aging 2.1 2.5 2.4 3.5 Film application case: Bonding PVC and fabric substrates. The bonding process is set according to the film's melting point. After bonding, performance testing is performed.

[0046] Example 1 Example 2 Example 3 Commercially available comparative example 1 Peel force N / 5cm 68 88 79 32 Temperature resistance 120℃, 30min No displacement No displacement No displacement Disengagement, displacement> 5cm From the above data, it can be seen that the adhesive films prepared in Examples 1-3 are about 30°C lower than commercially available products, achieving low-temperature activation, energy saving and high efficiency, and avoiding thermal deformation of the substrate.

[0047] Rheological data show that the film of the present invention completes rapid crosslinking within 30 minutes at 120° C., shortening the production cycle.

[0048] The formaldehyde and TVOC content is much lower than that of commercially available products, meeting the low emission and high environmental protection requirements of the automotive industry.

[0049] It is superior to commercially available films in key indicators such as peeling force, temperature resistance, and weather resistance, and is suitable for complex usage scenarios in automotive interiors.

[0050] Test data show that the adhesive film of the present invention has achieved technological breakthroughs in low-temperature activity, curing efficiency, environmental protection and bonding performance through formula and process optimization, solving the core defects of traditional adhesives and having significant industrial application value.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite film suitable for automotive interiors, characterized in that: The preparation raw materials include the following components in parts by weight: 40-50 parts of 4,4-dicyclohexylmethane diisocyanate, 35-50 parts of polyol, 25-40 parts of polyester diol, 1-3 parts of chain extender, 1-3 parts of prepolymer catalyst, 15-20 parts of end-capping agent and 1-3 parts of composite catalyst.

2. The adhesive film for automotive interior composite according to claim 1, characterized in that: The polyol includes at least one or more of trifunctional polyether polyol with a molecular weight of 5000, polypropylene glycol with a molecular weight of 1000, and polyethylene glycol with a molecular weight of 6000; The polyester diol includes at least one or more of polyneopentyl adipate diol with a molecular weight of 2000 and polybutylene succinate diol with a molecular weight of 2000; The chain extender includes at least one or more of diethylene glycol and diethylene glycol; The prepolymer catalyst includes at least one or more of dibutyltin dilaurate and bis(octyltin).

3. The adhesive film suitable for automotive interior composite according to claim 1, characterized in that: The end-capping agent includes at least one or more of acetyl tributyl citrate and acetylacetone semi-alcohol; The composite catalyst comprises at least one or more of dibutyltin dilaurate, bismorpholine diethyl ether, bis(2-ethylhexyl)tin salt, and tri(di-n-butyl)tin oxide.

4. The adhesive film for automotive interior composite according to claim 1, characterized in that: The invention also comprises 1-3 parts of a light stabilizer and 1-3 parts of an antioxidant, wherein the light stabilizer is bis(1,2,2,6,6-pentamethylpiperidinol) sebacate, and the antioxidant is isooctyl beta-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

5. A method for preparing a composite adhesive film for automobile interior, characterized in that: The following steps are involved: Step 1: preparing 4,4-dicyclohexylmethane diisocyanate, polyol, polyester diol, chain extender, prepolymer catalyst, end-capping agent and composite catalyst as raw materials; Step 2: Under nitrogen protection, add 4,4-dicyclohexylmethane diisocyanate to a reactor, raise the temperature to 75-80°C, add polyol, polyester diol, chain extender and prepolymer catalyst, and react at a constant temperature for 2-4 hours. After the NCO% of the reactant reaches the theoretical value, stop the reaction and cool to 40-60°C to prepare a blocked polyurethane prepolymer; Step 3: adding a blocking agent and a composite catalyst to the system of the prepared blocked polyurethane prepolymer, stirring, discharging and sealing for storage to prepare an aliphatic polyurethane adhesive; Step 4: preparing the prepared aliphatic polyurethane adhesive into a polyurethane film by roller coating, transfer, casting or calendaring; Step 5: Heat the prepared polyurethane film until its temperature reaches the melting point and then activate and unblock it, exposing the isocyanate groups; allow the unblocked polyurethane prepolymer to mature and react with the reactive groups in the system to quickly achieve bonding properties and bond the interior materials.

6. The method for preparing a composite adhesive film for automobile interior according to claim 5, characterized in that: In step 3, the stirring time is 20-40 minutes.