High-resilience polyurethane sponge for automotive trim and preparation method of high-resilience polyurethane sponge

Abstract

The invention discloses a high-resilience polyurethane sponge for automotive interiors and a preparation method thereof, belongs to the field of polyurethane sponges, and aims to solve the problems that an existing combination process of a gradient structure and a self-repairing function has a bottleneck, interface layering is easy to occur when the gradient structure and the self-repairing function are directly compounded, the overall mechanical property of the sponge is reduced, and the service life of the sponge is prolonged. The sponge comprises an edge area and a center area, the cross-linking density of the edge area is 30%-50% higher than that of the center area, and a continuous gradient cross-linking structure from the edge to the center is formed. The high cross-linked structure of the edge area provides basic strength support for the sponge, the tearing strength of the edge is improved by 30% or above in cooperation with the thickness design of 5-10 mm, the deformation rate is controlled to be 8% or below after a 75% compression cycle test, and the problem that the edge of a traditional sponge is prone to collapse after being cut is solved.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam, and more particularly to a high-resilience polyurethane foam for automotive interiors and its preparation method. Background Technology

[0002] High-resilience polyurethane foam for automotive interiors is widely used in components such as seats, steering wheels, and door panels due to its excellent resilience, support, and shock absorption properties.

[0003] In existing technologies, the preparation of this type of sponge mostly employs a molding foaming process. By adjusting the ratio of polyether polyol to isocyanate, the amount of foaming agent, and the reaction temperature, the high resilience of the sponge is achieved, with a resilience rate typically ≥40%. To improve the durability of the sponge, researchers have proposed several improvement schemes: for example, increasing the density of the edge region to form a gradient structure, and mechanically triggering the repair of micro-cracks. In addition, the industry often optimizes the curing temperature and time to reduce unreacted monomer residues inside the sponge, thereby improving overall stability.

[0004] However, existing technologies still have significant drawbacks:

[0005] On the one hand, a simple gradient structure sponge, although the gradient formed by density difference can improve the strength of the edge base, cannot repair the micro cracks at the edge after cutting. After long-term use, it will still collapse due to stress concentration.

[0006] On the other hand, sponges with only self-healing agents lack sufficient basic strength support, and under high-frequency loads, the edges are prone to macroscopic deformation.

[0007] Meanwhile, there are bottlenecks in the process of combining gradient structure and self-healing function. When the two are directly combined, interface delamination is likely to occur, which leads to a decline in the overall mechanical properties of the sponge and makes it difficult to meet the durability requirements of automotive interiors.

[0008] Therefore, the present invention provides a high-resilience polyurethane foam for automotive interiors and a method for preparing the same, in order to solve the above-mentioned technical problems. Summary of the Invention

[0009] To overcome the above problems, this invention aims to propose a high-resilience polyurethane foam for automotive interiors and its preparation method. The purpose is to solve the bottleneck in the current process of combining gradient structure and self-healing function. When the two are directly compounded, interface delamination is likely to occur, which leads to a decrease in the overall mechanical properties of the foam and makes it difficult to meet the durability requirements of automotive interiors.

[0010] Therefore, the specific technical solution adopted by the present invention is as follows:

[0011] According to one aspect of the present invention, a high-resilience polyurethane foam for automotive interiors is provided, the foam comprising an edge region and a central region, wherein the crosslinking density of the edge region is 30%-50% higher than that of the central region, forming a continuous gradient crosslinking structure from the edge to the center;

[0012] The thickness of the edge region is 5-10mm, accounting for 15%-20% of the total volume of the sponge;

[0013] The edge region also contains 3-5 wt% of a microencapsulated self-healing agent, wherein the microcapsules have a particle size of 5-10 μm, the core material contains isocyanate prepolymer and catalyst, and the wall material contains polyurea.

[0014] The isocyanate prepolymer is at least one of TDI prepolymer or MDI prepolymer, and its NCO content is 15-25 wt%.

[0015] The catalyst is at least one of triethylenediamine and dibutyltin dilaurate.

[0016] Optionally, the wall material of the microcapsule has a double-layer structure, with an inner layer of polyurea and an outer layer of silica. The double-layer wall material is prepared by in-situ polymerization, wherein the thickness of the inner polyurea layer is 0.5-2 μm and the thickness of the outer silica layer is 0.1-0.5 μm.

[0017] Optionally, the Shore C hardness of the edge region is 50-55, the Shore C hardness of the center region is 40-45, the overall resilience of the sponge is ≥45%, the tensile strength is ≥100kPa, and the elongation at break is ≥150%.

[0018] Optionally, the core material of the microcapsule further contains 0.1 wt% of a low-temperature catalyst, wherein the low-temperature catalyst is a dibutyltin dilaurate derivative, and the chemical structure of the low-temperature catalyst contains at least two tertiary amine groups and one organotin group.

[0019] A method for preparing high-resilience polyurethane foam for automotive interiors, the method comprising the following steps:

[0020] S1. Inject a highly cross-linked formulation into the edge area of ​​the mold. The highly cross-linked formulation contains an isocyanate component with an isocyanate index of 105-110, a polyether polyol component, and 3-5 wt% of a microencapsulated self-healing agent. Control the temperature of the edge area of ​​the mold to 60-70°C.

[0021] The isocyanate component is at least one of TDI-80 and MDI-50, and the polyether polyol component is a mixture of polyoxypropylene glycol and polyoxypropylene triol with a molecular weight of 3000-6000.

[0022] S2. 2-3 seconds after injecting the edge layer, inject the ordinary formula into the center area of ​​the mold. The ordinary formula contains an isocyanate component with an isocyanate index of 100 and a polyether polyol component. Control the temperature of the center area of ​​the mold to 50-55°C.

[0023] S3. After foaming, keep the mold at 60°C for 24 hours to form a gradient cross-linked structure.

[0024] Optionally, in the edge layer preparation step, the highly crosslinked formulation further includes 0.5 wt% of polyether-modified silicone oil, wherein the polyether-modified silicone oil has a viscosity of 1000-3000 mPa·s and an HLB value of 8-12.

[0025] Optionally, the injection volume ratio of the edge layer to the center layer is 1:4 to 1:5, and the injection uses a high-pressure mixing head with a mixing pressure of 12-18 MPa.

[0026] Optionally, the microencapsulated self-healing agent is uniformly dispersed in the highly cross-linked formulation by mechanical stirring at a speed of 1500 r / min for 5 minutes. During stirring, the temperature is controlled at 25±2℃ and the shear force is 500-1000 Pa.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] First, the highly cross-linked structure in the edge region provides basic strength support for the sponge. Combined with a thickness design of 5-10mm, the tear resistance of the edge is increased by more than 30%, and the deformation rate after 75% compression cycle test is controlled below 8%, solving the problem of easy collapse of the edge after traditional sponge is cut. At the same time, the microencapsulated self-healing agent (3-5wt%) added to the edge region can release isocyanate prepolymer through mechanical triggering, and complete the in-situ repair of micro-cracks under the action of humidity. This increases the repair efficiency at low temperature (-10℃) to 25%, and the activity retention rate of the repair agent in high temperature (80℃) environment exceeds 90%, overcoming the environmental adaptability defects of single self-healing solutions.

[0029] Secondly, by using a step-by-step injection process and temperature gradient control (60-70℃ at the edges and 50-55℃ at the center), combined with the interfacial compatibility of polyether-modified silicone oil, the bonding strength between the edge layer and the center layer is increased from 0.5MPa in the traditional process to over 1.2MPa, avoiding the risk of delamination in the composite structure, and achieving a yield rate of over 98%. Furthermore, the overall sponge's resilience remains above 45%, and the Shore hardness gradient matches ergonomic requirements (50-55 at the edges and 40-45 at the center), balancing high resilience performance with ride comfort. In addition, the process does not require modification of existing production lines; it can be achieved simply by adjusting the raw material ratio and temperature control parameters, resulting in low modification costs, suitability for mass production, and meeting the comprehensive requirements of automotive interiors for durability, stability, and economy. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0031] Example 1

[0032] According to an embodiment of the present invention, a high-resilience polyurethane foam for automotive interior is provided, the foam comprising an edge region and a central region, wherein the crosslinking density of the edge region is 30%-50% higher than that of the central region, forming a continuous gradient crosslinking structure from the edge to the center;

[0033] The thickness of the edge area is 5-10mm, accounting for 15%-20% of the total volume of the sponge;

[0034] The edge region also contains 3-5 wt% of microencapsulated self-healing agent, wherein the microcapsules have a particle size of 5-10 μm, the core material contains isocyanate prepolymer and catalyst, and the wall material contains polyurea;

[0035] The isocyanate prepolymer is at least one of TDI prepolymer or MDI prepolymer, and its NCO content is 15-25 wt%.

[0036] The catalyst is at least one of triethylenediamine and dibutyltin dilaurate.

[0037] The wall material of the microcapsule has a double-layer structure, with an inner layer of polyurea and an outer layer of silica. The double-layer wall material is prepared by in-situ polymerization, wherein the thickness of the inner polyurea layer is 0.5-2 μm and the thickness of the outer silica layer is 0.1-0.5 μm.

[0038] The Shore C hardness of the edge area is 50-55, and the Shore C hardness of the center area is 40-45. The overall resilience of the sponge is ≥45%, the tensile strength is ≥100kPa, and the elongation at break is ≥150%.

[0039] The core material of the microcapsule also contains 0.1 wt% of a low-temperature catalyst, which is a dibutyltin dilaurate derivative, and the chemical structure of the low-temperature catalyst contains at least two tertiary amine groups and one organotin group.

[0040] A method for preparing high-resilience polyurethane foam for automotive interiors, the method comprising the following steps:

[0041] S1. Inject a highly cross-linked formulation into the edge area of ​​the mold. The highly cross-linked formulation contains an isocyanate component with an isocyanate index of 105-110, a polyether polyol component, and 3-5 wt% of a microencapsulated self-healing agent. Control the temperature of the edge area of ​​the mold to 60-70°C.

[0042] The isocyanate component is at least one of TDI-80 and MDI-50, and the polyether polyol component is a mixture of polyoxypropylene glycol and polyoxypropylene triol with a molecular weight of 3000-6000.

[0043] S2. 2-3 seconds after injecting the edge layer, inject the ordinary formula into the center area of ​​the mold. The ordinary formula contains an isocyanate component with an isocyanate index of 100 and a polyether polyol component. Control the temperature of the center area of ​​the mold to 50-55°C.

[0044] S3. After foaming, keep the mold at 60°C for 24 hours to form a gradient cross-linked structure.

[0045] In the edge layer preparation step, the highly crosslinked formulation also contains 0.5 wt% of polyether-modified silicone oil, wherein the polyether-modified silicone oil has a viscosity of 1000-3000 mPa·s and an HLB value of 8-12.

[0046] The injection volume ratio of the edge layer to the center layer is 1:4-1:5, and the injection is performed using a high-pressure mixing head with a mixing pressure of 12-18 MPa.

[0047] The microencapsulated self-healing agent was uniformly dispersed in the highly cross-linked formulation by mechanical stirring at a speed of 1500 r / min for 5 minutes. During the stirring process, the temperature was controlled at 25±2℃ and the shear force was 500-1000 Pa.

[0048] Example 2

[0049] A method for preparing high-resilience polyurethane foam for automotive interiors includes the following steps:

[0050] S1, Highly Crosslinked Formulation (Edge Layer): 70 parts of polyether polyol (molecular weight 3000, 3 functionalities), 30 parts of isocyanate component (MDI, isocyanate index 105), 4 parts of microencapsulated self-healing agent (core material is MDI prepolymer + 0.5 parts of triethylenediamine catalyst, wall material is polyurea, particle size 5-8μm), and 0.5 parts of polyether modified silicone oil (viscosity 2000mPa·s, HLB value 10).

[0051] S2, 75 parts of polyether polyol (molecular weight 3500, 3 functionalities) and 25 parts of isocyanate component (MDI, isocyanate index 100).

[0052] S3. Preheat the mold to 50°C, inject the highly cross-linked formula into the edge area of ​​the mold through a high-pressure mixing head (pressure 15MPa), control the temperature of the mold edge to 65°C, and react for 30 seconds until the initial gel is formed.

[0053] After a 2-second delay, inject the central formula into the center area of ​​the mold, control the temperature of the mold center to 50°C, and allow the two components to naturally blend and foam, with a total foaming time of 2.5 minutes.

[0054] S4. After foaming, the sponge is cured in a 60℃ oven for 24 hours to obtain a gradient-self-healing composite sponge with an edge area thickness of 8mm, where the edge area accounts for 18% of the total volume.

[0055] Experimental Example 1

[0056] The experimental process based on Example 2 is as follows:

[0057] Test method:

[0058] Crosslinking density test: The crosslinking density of the edge and center regions was tested using the equilibrium swelling method (unit: mol / cm³). 3 ), calculate the ratio of the two;

[0059] Edge compression deformation test: According to GB / T10807-2006, the edge area is subjected to a 75% compression cycle test (1000 times, 23℃), and the permanent deformation rate after compression is recorded.

[0060] Self-healing efficiency test: After trimming the edge, apply 50% compression load 100 times, monitor the change in intensity of characteristic peaks of isocyanate group (-NCO) before and after repair by infrared spectroscopy, and calculate the repair rate.

[0061] Experimental results:

[0062] Crosslinking density in the edge region: 3.2 × 10⁻⁶ -4 mol / cm 3 Central area: 2.3 × 10 -4 mol / cm3 The ratio was 1.39 (i.e., 39% higher);

[0063] Edge deformation rate after 1000 compressions: 7.8% (compared to 35% for traditional uniform sponge);

[0064] Self-healing efficiency: 22% (10% for self-healing sponges without gradient structures).

[0065] Example 3

[0066] A method for preparing high-resilience polyurethane foam for automotive interiors includes the following steps:

[0067] S1, Highly Crosslinked Formulation (Edge Layer): 68 parts of polyether polyol (molecular weight 3000, 3 functionalities), 32 parts of isocyanate component (TDI, isocyanate index 110), 5 parts of microencapsulated self-healing agent (core material is TDI prepolymer + 0.3 parts of dibutyltin dilaurate derivative catalyst, wall material is polyurea-silica bilayer structure, inner polyurea thickness 1μm, outer silica thickness 0.3μm, particle size 8-10μm), and 0.5 parts of polyether modified silicone oil (viscosity 3000mPa·s, HLB value 12).

[0068] S2, 72 parts of polyether polyol (molecular weight 3500, 3 functionalities) and 28 parts of isocyanate component (TDI, isocyanate index 100).

[0069] S3. Preheat the mold to 55°C, inject the highly cross-linked formula into the edge area of ​​the mold through a high-pressure mixing head (pressure 18MPa), control the temperature of the mold edge to 70°C, and react for 25 seconds until the initial gel is formed.

[0070] After a 3-second delay, inject the central formula into the center area of ​​the mold, control the temperature of the mold center to 55℃, and allow the two components to naturally blend and foam, with a total foaming time of 3 minutes.

[0071] S4. After foaming, the sponge is cured in a 60℃ oven for 24 hours to obtain a gradient-self-healing composite sponge with an edge area thickness of 10mm, where the edge area accounts for 20% of the total volume.

[0072] Experimental Example 2

[0073] The experimental process based on Example 3 is as follows:

[0074] Test method:

[0075] High and low temperature cycling test: The sponge is cycled 50 times between -40℃ (4 hours) and 80℃ (4 hours), and the edge tear resistance is tested after the cycle (according to ISO34-1 standard);

[0076] Microcapsule activity test: After being placed at 80℃ for 72 hours, the residual amount of NCO groups of the self-healing agent in the microcapsules in the edge area was determined (by chemical titration).

[0077] Resilience test: Test the resilience rate of the central area of ​​the sponge according to GB / T6670-2008.

[0078] Experimental results:

[0079] Edge tear resistance after high and low temperature cycling: 1.9 N / mm (1.2 N / mm for traditional composite sponge);

[0080] The residual NCO content of the self-healing agent at 80℃ is 90% (70% for single-layer wall material microcapsules);

[0081] Central area rebound rate: 46% (meets the high resilience sponge standard of ≥40%).

[0082] Although the present invention has been disclosed above with reference to preferred embodiments, the embodiments are merely examples for illustrative purposes and are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. The scope of protection claimed by the present invention should be determined by the claims.

Claims

1. A high-resilience polyurethane foam for automotive interiors, characterized in that, The sponge includes an edge region and a central region, wherein the crosslinking density of the edge region is 30%-50% higher than that of the central region, forming a continuous gradient crosslinking structure from the edge to the center; The thickness of the edge region is 5-10mm, accounting for 15%-20% of the total volume of the sponge; The edge region also contains 3-5 wt% of a microencapsulated self-healing agent, wherein the microcapsules have a particle size of 5-10 μm, the core material contains isocyanate prepolymer and catalyst, and the wall material contains polyurea. The isocyanate prepolymer is at least one of TDI prepolymer or MDI prepolymer, and its NCO content is 15-25 wt%. The catalyst is at least one of triethylenediamine and dibutyltin dilaurate.

2. The high-resilience polyurethane foam for automotive interiors according to claim 1, characterized in that, The wall material of the microcapsule has a double-layer structure, with an inner layer of polyurea and an outer layer of silica. The double-layer wall material is prepared by in-situ polymerization, wherein the thickness of the inner polyurea layer is 0.5-2 μm and the thickness of the outer silica layer is 0.1-0.5 μm.

3. The high-resilience polyurethane foam for automotive interiors according to claim 1, characterized in that, The Shore C hardness of the edge region is 50-55, the Shore C hardness of the center region is 40-45, the overall resilience of the sponge is ≥45%, the tensile strength is ≥100kPa, and the elongation at break is ≥150%.

4. The high-resilience polyurethane foam for automotive interiors according to claim 1, characterized in that, The core material of the microcapsule also contains 0.1 wt% of a low-temperature catalyst, which is a dibutyltin dilaurate derivative. The chemical structure of the low-temperature catalyst contains at least two tertiary amine groups and one organotin group.

5. The method for preparing a high-resilience polyurethane foam for automotive interiors according to claim 1, characterized in that, This method includes the following steps: S1. Inject a highly cross-linked formulation into the edge area of ​​the mold. The highly cross-linked formulation contains an isocyanate component with an isocyanate index of 105-110, a polyether polyol component, and 3-5 wt% of a microencapsulated self-healing agent. Control the temperature of the edge area of ​​the mold to 60-70°C. The isocyanate component is at least one of TDI-80 and MDI-50, and the polyether polyol component is a mixture of polyoxypropylene glycol and polyoxypropylene triol with a molecular weight of 3000-6000. S2. 2-3 seconds after injecting the edge layer, inject the ordinary formula into the center area of ​​the mold. The ordinary formula contains an isocyanate component with an isocyanate index of 100 and a polyether polyol component. Control the temperature of the center area of ​​the mold to 50-55°C. S3. After foaming, keep the mold at 60°C for 24 hours to form a gradient cross-linked structure.

6. The method for preparing a high-resilience polyurethane foam for automotive interiors according to claim 5, characterized in that, In the edge layer preparation step, the highly crosslinked formulation also includes 0.5 wt% of polyether-modified silicone oil, wherein the viscosity of the polyether-modified silicone oil is 1000-3000 mPa·s and the HLB value is 8-12.

7. The method for preparing a high-resilience polyurethane foam for automotive interiors according to claim 5, characterized in that, The injection ratio of the edge layer to the center layer is 1:4 to 1:5, and the injection uses a high-pressure mixing head with a mixing pressure of 12-18 MPa.

8. The method for preparing a high-resilience polyurethane foam for automotive interiors according to claim 5, characterized in that, The microencapsulated self-healing agent is uniformly dispersed in the highly cross-linked formulation by mechanical stirring at a speed of 1500 r / min for 5 minutes. During the stirring process, the temperature is controlled at 25±2℃ and the shear force is 500-1000 Pa.