Stamping-resistant functional resin for reflective material and preparation method thereof

Abstract

The invention discloses a preparation method of a stamping-resistant functional resin for a reflective material, which comprises the following steps: synergistically modifying hyperbranched polyurethane and polyether ester, and combining a dynamic cross-linking technology and a solution type thermal initiation process, thereby obtaining the stamping-resistant functional resin for the reflective material. The technical contradiction of the existing reflective film and license plate film resin in the aspects of stamping resistance (falling ball impact is greater than or equal to 9J), metal base material adhesive force (greater than 8.5 N / cm), high transparency (greater than or equal to 95%) and extensibility (greater than or equal to 500%) is solved; the resin does not crack in a temperature change cycle of-40 DEG C to 120 DEG C, is resistant to solvent wiping for more than or equal to 200 times, is particularly suitable for high-end fields such as motor vehicle license plate films and the like, and fills the technical blank of high-weather-resistant reflective materials.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and specifically relates to a stamping-resistant functional resin for reflective materials and a preparation method thereof. Background Art

[0002] Analysis of Defects in the Prior Art: 1. Resin for license plate film: CN202210345678A (high refractive index license plate film resin): The refractive index reaches 1.63 by sulfur element modification, but the dynamic crosslinking density is low (2.3×10 -4 mol / cm 3 ), resulting in insufficient impact resistance (falling ball test 7.5J), and the adhesion decreases by more than 40% under high temperature and high humidity (85℃ / 85%RH).

[0003] JP2022078911A (fluorosilicon-modified acrylic resin): It has excellent weather resistance (ΔE<2.0 after QUV 3000h), but the curing shrinkage rate is as high as 8.2%, resulting in stress whitening (haze≥18%), and obvious low-temperature brittleness (-40℃ impact fracture elongation rate<100%).

[0004] CN113831524A (epoxy-acrylic composite resin): The metal adhesion reaches 7.8N / cm, but the light transmittance is only 82%, and the solvent system contains toluene (VOCs>400g / L), which does not meet the environmental protection regulations.

[0005] 2. Resin for reflective film substrate: CN103450216A (solution-type acrylic resin): Toluene is used as the solvent, and the VOCs emission exceeds the standard (>350g / L). After curing, the hardness is low (pencil hardness≤H), and the resistance to gravel impact is only 6J.

[0006] JP2021085567A (fluorine-modified polyurethane resin): It has excellent chemical resistance, but it decomposes when the processing temperature>150℃, resulting in a yellowing index Δb>4.5, and the cost is high (unit price>￥85,000 / ton).

[0007] The following key problems exist in the prior art: Performance imbalance: It is difficult to coexist high refractive index (≥1.60) and high light transmittance (≥90%), and impact resistance and adhesion restrict each other; Environmental protection defects: High-performance resins mostly rely on high-VOCs solvents (toluene, xylene), which do not meet the GB 38508-2020 standard; Process limitations: Photocurable resins rely on expensive equipment, while thermosetting resins have high energy consumption and are prone to yellowing (Δb > 3.0). Summary of the Invention

[0008] To solve the problems of brittle fracture, optical property deterioration, and insufficient environmental friendliness of traditional reflective film resins during stamping processing, and to break through the technical contradiction between high adhesion, stamping resistance, and low VOC emissions. Through the molecular design and dynamic crosslinking technology of hyperbranched polyurethane and polyether ester, the present invention significantly improves the mechanical strength, optical properties, and environmental tolerance of the resin, and is particularly suitable for special reflective products that need to withstand extreme stamping stress and outdoor aging, such as license plate films.

[0009] To achieve the above object, the present invention provides the following technical solutions: The present invention provides a preparation method of a stamping-resistant functional resin for reflective materials, comprising the following steps: Prepare hyperbranched polyurethane-polyether ester copolymer: Mix amide, isocyanate monomer, high molecular polyether ester, and catalyst, and react at 60 - 80°C for 2 - 3 h; Prepare caprolactone-modified acrylate chain extender: Chain extend caprolactone-grafted hydroxyacrylate monomer and isocyanate according to a mass ratio of 1.1 - 1.3:1, and react at 70 - 80°C for 4 - 6 h; Prepare resin solution: Mix the products of step (1) and (2) in a mass ratio of 1:1, add ethyl acetate and azobisisobutyronitrile, and react at 60 - 80°C for 3 - 5 h to form a nano-interpenetrating network structure.

[0010] Further, in step (1), by mass percentage, amide is 40 - 55%, isocyanate monomer is 30 - 50%, high molecular polyether ester is 5 - 15%, and catalyst is 0.5 - 2%.

[0011] Further, in step (1), the molecular weight of the high molecular polyether ester is 2000 - 5000, the hydroxyl functionality is 2 - 4, and dynamic mechanical analysis shows that the loss factor tan δ = 0.12 - 0.18.

[0012] Further, the catalyst is an organic bismuth catalyst.

[0013] Further, the amide is one or more of N,N-dimethylacetamide and N,N-dimethylformamide.

[0014] Further, in step (3), add 40 - 60% ethyl acetate ((ethyl acetate mass / total raw material mass of step (1) and (2)) * 100%) and 0.5 - 1.5% azobisisobutyronitrile ((azobisisobutyronitrile mass / total raw material mass of step (1) and (2)) * 100%).

[0015] Further, in step (3), the phase domain size of the nano-interpenetrating network structure < 50 nm.

[0016] The present invention also provides a stamping-resistant functional resin for reflective materials prepared by the preparation method as described above.

[0017] The present invention also provides an application of the stamping-resistant functional resin for reflective materials as described above in the preparation of motor vehicle reflective license plate films.

[0018] Further, it is coated on an anodic aluminum oxide substrate by screen printing to form a 5 - 8 μm thin film.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The hyperbranched polyurethane main chain (HDI / IPDI mixed system) of the present invention provides a rigid skeleton (storage modulus E' = 1.5 GPa), and the flexible chain of the high molecular polyether ester (T g = -25 °C) forms an energy dissipation network through dynamic transesterification, and the SEM of the impact fracture surface shows the characteristics of ductile fracture; The present invention applies the block copolymerization of hyperbranched polyurethane and high molecular polyether ester to the field of reflective materials, so that the tensile strength / elongation rate reaches 30 MPa / 500%, which is 60% higher than that of traditional resins. Using ethyl acetate as a solvent (VOCs = 175 g / L), cooperating with AIBN for low-temperature initiation (decomposition temperature 64 °C), and the curing temperature ≤ 100 °C, the energy consumption is reduced by 50%.

[0020] Through the synergistic modification of hyperbranched polyurethane and polyether ester, combined with the dynamic crosslinking technology and the solution-type thermal initiation process, the technical contradictions of the existing reflective film and license plate film resins in terms of stamping resistance (falling ball impact ≥ 9 J), adhesion to metal substrates (> 8.5 N / cm), high transparency (≥ 95%) and extensibility (≥ 500%) are solved; this resin has no cracking during the temperature change cycle of -40 °C to 120 °C and can withstand solvent wiping ≥ 200 times, and is particularly suitable for high-end fields such as motor vehicle license plate films, filling the technical gap of highly weather-resistant reflective materials. Specific Embodiments

[0021] The technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Example 1

[0022] Preparation of Stamping-Resistant Resin (1) Synthesis of hyperbranched polyurethane-polyether ester: Raw materials: 50 g of N,N-dimethylacetamide, 38 g of HDI / IPDI (7:3), 10 g of high molecular polyether ester (Mw = 3000) (Shanghai Yuyu New Materials Technology Co., Ltd., model 174), 2 g of organic bismuth (Shanghai Deyin Chemistry Co., Ltd.: brand DY-20); Process: React at 70 °C for 2.5 h and degas under reduced pressure.

[0023] (2)Chain extension reaction: Caprolactone-grafted hydroxyacrylate monomer (Korea Miwon: brand M100) and HDI (Wanhua Chemical) are mixed at a mass ratio of 1.2:1 and reacted at 75 °C for 5 h.

[0024] (3)Preparation of resin solution: Mix the products of steps (1) and (2) (50 g, 50 g), add 50 g of ethyl acetate and 1 g of AIBN, and react at 75 °C for 4 h; Coat on an anodized aluminum substrate by screen printing, cure at 90 °C for 1 h to form a film, and form a 5 - 8 μm thin film.

[0025] Performance testing: Ball drop impact: 9.1 J (GB / T 1732); Adhesion to metal: 9.2 N / cm (ISO 4624); Light transmittance: 95.5% (GB / T 2410); Tensile strength: 31 MPa (GB / T 1040.3 - 2022); Elongation (50 μm): 520% (GB / T 1040.3 - 2022).

[0026] Storage modulus (E’) testing: Use a dynamic thermomechanical analyzer (DMA) to test the prepared resin film. Set the temperature range from -50 °C to 150 °C, the heating rate is 5 °C / min, and the frequency is 1 Hz. During the test, record the change of the storage modulus with temperature. The results show that at room temperature (25 °C), the storage modulus E’ of this resin film = 1.5 GPa, proving that the hyperbranched polyurethane main chain (HDI / IPDI mixed system) provides a rigid skeleton.

[0027] Glass transition temperature (Tg) testing: Also use a dynamic thermomechanical analyzer (DMA). Based on the storage modulus data of the above test, determine the glass transition temperature of the flexible chain of the high molecular polyether ester by analyzing the change of the curve. The test results show that the Tg of the flexible chain of the high molecular polyether ester = -25 °C.

[0028] SEM Observation of Impact Cross-Section: The impact cross-section of the resin film after the falling ball impact test was processed, and its microstructure was observed using a scanning electron microscope (SEM). The observation results showed that the impact cross-section presented ductile fracture characteristics, further verifying that the flexible chains of the polyether ester formed an energy dissipation network through dynamic transesterification.

[0029] Comparison with Traditional Resins: Traditional resin samples commonly used in the field of reflective materials on the market were collected, and their tensile strength and elongation were tested according to the same test methods (tensile strength test was based on GB / T 1040.3 - 2022, and elongation test was based on GB / T 1040.3 - 2022). The test results showed that the average tensile strength of the traditional resin was 18.75 MPa, and the average elongation was 312.5%. While the tensile strength of the resin in this example was 31 MPa, and the elongation was 520%. Compared with the traditional resin, the tensile strength increased by (31 - 18.75)÷18.75×100% = 65%, and the elongation increased by (520 - 312.5)÷312.5×100% = 66%, proving that the application of hyperbranched polyurethane and polyether ester block copolymerization in the field of reflective materials in this invention increased the tensile strength / elongation by about 60% compared with traditional resins.

[0030] Tests Related to Energy Consumption: Record the energy consumption during the curing process of the resin in this example, including information such as equipment power and curing time. At the same time, collect the energy consumption data of the traditional resin curing process (the curing temperature of the traditional resin was about 200 °C, and the curing time was the same). After calculation, the resin of this invention used ethyl acetate as a solvent and was initiated at low temperature with AIBN, and the curing temperature ≤ 100 °C, and the energy consumption was reduced by 50% compared with the traditional resin.

[0031] VOCs Content Test: The VOCs content in the ethyl acetate solvent was tested according to relevant standards (such as HJ 583-2010). The test results showed that VOCs = 175 g / L. Example 2

[0032] Preparation of Impact-Resistant Resin (1) Synthesis of Hyperbranched Polyurethane-Polyether Ester: Raw Materials: 50 g of N,N-dimethylacetamide, 38 g of HDI / IPDI (7:3), 10 g of polyether ester (Mw = 3000) (Shanghai Yuyu New Materials Technology Co., Ltd., model 174), and variable addition of organic bismuth (Shanghai Deyin Chemistry Co., Ltd.: brand DY-20) (0.5 g, 1.0 g, 2.0 g); Process: React at 70 °C for 2.5 h and perform vacuum degassing.

[0033] (2) Chain Extension Reaction: The same as in Example 1.

[0034] (3) Preparation of resin solution: The same as in Example 1.

[0035] The performance test results are shown in Table 1 below.

[0036] Table 1 Performance test results of Example 2 Catalyst dosage (g) Metal adhesion force N / cm Tensile strength (MPa) Impact strength (J) 0.5 9.1 35 8.2 1.0 9.5 38 9.5 2.0 9.2 31 9.1 Conclusion: When the catalyst dosage is 1.0 g (1.0%), the performance is optimal.

[0037] Storage modulus (E’), glass transition temperature (Tg), SEM observation of impact fracture surface, comparison with traditional resin (tensile strength and elongation), energy consumption related tests, and VOCs content tests. The test methods and standards for each item are the same as those in Example 1 to further verify the beneficial effects of the present invention, the stability and consistency under different catalyst dosages. The test results are as follows: Storage modulus (E’): At room temperature (25 °C), the storage modulus of the resin film with different catalyst dosages is about 1.5 GPa, and the fluctuation range is less than ±5%.

[0038] Glass transition temperature (Tg): The Tg of the flexible chain of the high molecular polyether ester is about -25 °C, and the fluctuation range is less than ±2 °C.

[0039] SEM observation of impact fracture surface: The impact fracture surfaces of the resin films with different catalyst dosages all show the characteristics of ductile fracture.

[0040] Comparison with traditional resin (tensile strength and elongation): The improvement ranges of the tensile strength and elongation of the resin under different catalyst dosages compared with the traditional resin are both about 60%.

[0041] Energy consumption related tests: The energy consumption is reduced by about 50% compared with the traditional resin.

[0042] VOCs content tests: The VOCs content is about 175 g / L, and the fluctuation range is less than ±5 g / L. Comparative Example 1

[0043] Preparation of stamping-resistant resin (1)Synthesis of hyperbranched polyurethane-polyether ester: Raw materials: 50 g of N,N-dimethylacetamide, 38 g of HDI / IPDI (7:3), 1 g of high molecular polyether ester (Mw = 3000) (Shanghai Yuyu New Materials Technology Co., Ltd., model 174), 2 g of organic bismuth (Shanghai Deyin Chemical Co., Ltd.: brand DY-20); Process: React at 70 °C for 2.5 h, and carry out vacuum defoaming.

[0044] (2)Chain extension reaction: The caprolactone-grafted hydroxyacrylate monomer (Korea Miawon: grade M100) and HDI (Wanhua Chemical) were mixed at a mass ratio of 1.2:1 and reacted at 75 °C for 5 h.

[0045] (3)Preparation of resin solution: The products from steps (1) and (2) were mixed (50 g:50 g), 50 g of ethyl acetate and 1 g of AIBN were added, and the mixture was reacted at 75 °C for 4 h; It was coated on an anodized aluminum substrate by screen printing and cured at 90 °C for 1 h to form a film.

[0046] Performance testing: Falling ball impact: 6.1 J (GB / T 1732); Adhesion to metal: 8.2 N / cm (ISO 4624); Light transmittance: 95.5% (GB / T 2410); Tensile strength: 15 MPa (GB / T 1040.3-2022); Elongation (50 μm): 220% (GB / T 1040.3-2022). Comparative Example 2

[0047] Preparation of stamping-resistant resin (1)Synthesis of hyperbranched polyurethane-polyester: Raw materials: 50 g of N,N-dimethylacetamide, 38 g of HDI / IPDI (7:3), 1 g of high molecular weight polyether ester (Mw = 3000) (Shanghai Yuyu New Material Technology Co., Ltd., model 174), 0.1 g of organic bismuth (Shanghai Deyin Chemical Co., Ltd.: grade DY-20); Process: React at 70 °C for 2.5 h and carry out vacuum defoaming.

[0048] (2)Chain extension reaction: The caprolactone-grafted hydroxyacrylate monomer (Korea Miawon: grade M100) and HDI (Wanhua Chemical) were mixed at a mass ratio of 1.3:1 and reacted at 75 °C for 5 h.

[0049] (3)Preparation of resin solution: The products from steps (1) and (2) were mixed (50 g:50 g), 50 g of ethyl acetate and 1 g of AIBN were added, and the mixture was reacted at 75 °C for 4 h; It was coated on an anodized aluminum substrate by screen printing and cured at 90 °C for 1 h to form a film.

[0050] Performance testing: Falling ball impact: 5.1 J (GB / T 1732); Adhesion to metal: 6.2 N / cm (ISO 4624); Light transmittance: 94.5% (GB / T 2410); Tensile strength: 12 MPa (GB / T 1040.3 - 2022); Elongation (50um) 180% (GB / T 1040.3 - 2022).

[0051] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non - exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0052] It should be noted that the above content only illustrates the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a stamping-resistant functional resin for reflective material, characterized in that: The following steps are involved: Preparation of hyperbranched polyurethane-polyether ester copolymer: amide, isocyanate monomer, high molecular weight polyether ester and catalyst are mixed and reacted at 60-80°C for 2-3h; Preparation of caprolactone modified acrylate chain extender: chain extend caprolactone grafted hydroxy acrylate monomer and isocyanate at a mass ratio of 1.1 to 1.3:1, and react at 70 to 80° C. for 4 to 6 hours; Prepare a resin solution: mix the product of step (1) and the product of step (2) in a mass ratio of 1:1, add ethyl acetate and azobisisobutyronitrile, and react at 60-80° C. for 3-5 hours to form a nano interpenetrating network structure.

2. The method for preparing a punch-resistant functional resin for reflective material according to claim 1, characterized in that: In step (1), by mass percentage, the amide is 40-55%, the isocyanate monomer is 30-50%, the polymer polyether ester is 5-15%, and the catalyst is 0.5-2%.

3. The method for preparing a punch-resistant functional resin for reflective material according to claim 1, characterized in that: In step (1), the molecular weight of the polymer polyether ester is 2000-5000, the hydroxyl functionality is 2-4, and the dynamic mechanical analysis shows that the loss factor tan δ is 0.12-0.

18.

4. The method for preparing a punch-resistant functional resin for reflective material according to claim 1, characterized in that: The catalyst is an organic bismuth catalyst.

5. The method for preparing a punch-resistant functional resin for reflective material according to claim 1, characterized in that: The amide is one or more of N,N-dimethylacetamide and N,N-dimethylformamide.

6. The method for preparing a punch-resistant functional resin for reflective material according to claim 1, characterized in that: In step (3), the product of step (1) and the product of step (2) are mixed in a mass ratio of 1:1 to obtain a mixture, and 40 to 60% by mass of ethyl acetate and 0.5 to 1.5% by mass of azobisisobutyronitrile are added to the mixture.

7. The method for preparing a punch-resistant functional resin for reflective material according to claim 1, characterized in that: In step (3), the phase domain size of the nano interpenetrating network structure is less than 50 nm.

8. A stamping-resistant functional resin for reflective material prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the punch-resistant functional resin for reflective material as claimed in claim 8 in preparing reflective license plate film for motor vehicles.

10. The use of a punch-resistant functional resin for reflective material according to claim 9 in preparing a reflective license plate film for a motor vehicle, characterized in that: The film is coated on anodized aluminum substrate by screen printing to form a 5-8 μm thin film.