A photocurable polyurethane resin, its preparation method and application

Abstract

The present invention relates to a photocurable polyurethane resin, a preparation method and an application thereof, belonging to the technical field of polyurethane materials. The raw materials for preparing the photocurable polyurethane resin include a photosensitive photocurable monomer and a polyurethane prepolymer; the specific preparation method of the photosensitive photocurable monomer comprises the following steps: mixing acrylic acid, glycidyl acrylate, catalyst A and inhibitor, and reacting at 100-110 °C for 3-6 h to obtain the photosensitive photocurable monomer; the molar ratio of acrylic acid to glycidyl acrylate is (1.02-1.05):1. The photocurable polyurethane resin provided by the present invention has good photocuring activity, can greatly improve the preparation efficiency of shock-absorbing materials, and the obtained photocurable polyurethane material has a narrow molecular weight, low internal heat generation during use, and can effectively enhance its shock-absorbing life.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane materials, and in particular to a photocurable polyurethane resin, a preparation method thereof, and an application thereof. Background Art

[0002] Vibration damping has important uses in household items, mechanical equipment, railway tracks, bridges, aerospace, etc. Vibration damping materials are mainly used to absorb and reduce vibrations, which can improve the operating stability and service life of equipment, thus achieving good vibration damping effects. In the actual application process, due to the need for long-term high-intensity vibration abrasion and tensile compression, vibration damping materials will generate a certain amount of heat during long-term fatigue movement. When the heat reaches a certain temperature, further abrasion will cause irreversible deformation. Continuous accumulation of the vibration damping materials will result in damage, thus reducing their service life, and they need to be replaced in a timely manner, which in turn affects work efficiency and increases economic costs.

[0003] Polyurethane materials have the advantages of light weight, environmental protection, better temperature stability, impact resistance, and wear resistance. Polyurethane vibration damping materials have attracted more and more attention. However, existing polyurethane vibration damping materials still have the problem of a significant decrease in vibration damping effect after long-term use.

[0004] In addition, most of the commonly used vibration damping materials on the market are mainly thermally cured, with a preparation time of mostly 16 - 24 h, and a few also require a process of more than 4 h, and the site turnover space is also relatively large. The choice of photocuring can significantly improve production efficiency.

[0005] Therefore, it is of great significance to provide a photocurable vibration damping polyurethane material with a high vibration damping life. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a photocurable polyurethane resin, a preparation method thereof, and an application thereof. The photocurable polyurethane resin has good photocuring activity, can greatly improve the preparation efficiency of vibration damping materials, and the photocurable polyurethane material prepared therefrom has a narrow molecular weight. During use, the internal heat generation is low, which can effectively enhance its vibration damping life.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a photocurable polyurethane resin, and the raw materials for preparing the photocurable polyurethane resin include a photosensitive photocurable monomer and a polyurethane prepolymer;

[0009] The specific preparation method of the photosensitive photocurable monomer includes the following steps:

[0010] Mix acrylic acid, glycidyl acrylate, catalyst A and inhibitor, and react at 100 - 110 °C for 3 - 6 h to obtain the photosensitive photocurable monomer;

[0011] The molar ratio of the acrylic acid to the glycidyl acrylate is (1.02 - 1.05):1;

[0012] Based on the total mass of the acrylic acid and the glycidyl acrylate being 100%, the content of catalyst A is 0.8 - 1.2%;

[0013] Based on the total mass of the acrylic acid and the glycidyl acrylate being 100%, the content of the inhibitor is 0.05 - 0.2%.

[0014] The photosensitive photocurable monomer obtained by the reaction of acrylic acid and glycidyl acrylate in the present invention has a specific bifunctional monohydroxy structure. When combined with the polyurethane prepolymer, it can make the molecules of the obtained photocurable polyurethane resin carry more active vinyl groups. The vinyl groups are less affected by steric hindrance, enabling the double bonds to be fully and effectively utilized during the photocuring process, thereby making it have strong photocuring activity. While greatly improving the preparation efficiency of the damping material, it can preferably increase the crosslinking degree to form a network structure, and then has excellent damping effects. Moreover, the molecular weight of the obtained photocurable polyurethane material is narrow, and during use, the internal heat generation is low, making its wear resistance performance excellent, thereby effectively enhancing its damping life; at the same time, it also has a strong buffering effect and excellent impact resistance performance.

[0015] In the present invention, the molar ratio of the acrylic acid to the glycidyl acrylate is (1.02 - 1.05):1. Among them, (1.02 - 1.05) can be, for example, 1.02, 1.03, 1.04 or 1.05, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0016] In the present invention, when the molar ratio of the acrylic acid to the glycidyl acrylate is (1.02 - 1.05):1, the carboxyl group (-COOH) in the acrylic acid and the epoxy group in the glycidyl acrylate undergo a ring-opening reaction, thereby obtaining a photosensitive photocurable monomer with a monohydroxy structure having low by-products and vinyl groups at both ends, which is conducive to its full combination with the subsequent polyurethane prepolymer to obtain a photocurable polyurethane resin with excellent damping performance. When the molar ratio of the acrylic acid to the glycidyl acrylate is too high, there is too much acid residue in the system, which will affect the water resistance of the product and make it prone to hydrolysis; when the molar ratio of the two is too low, at this time, the glycidyl acrylate is too high and there is too much epoxy group residue, making the product quality unstable, such as the viscosity increasing continuously with the increase of the storage time at room temperature.

[0017] In other embodiments, acrylic acid can also be replaced with C1-C3 (e.g., C1, C2, or C3) alkylacrylic acid.

[0018] In the specific preparation method of the photosensitive photocurable monomer provided by the present invention, 100-110 °C can be 100 °C, 101 °C, 102 °C, 103 °C, 104 °C, 105 °C, 106 °C, 107 °C, 108 °C, 109 °C, or 110 °C, etc.; 3-6 h can be 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, or 6 h, etc.

[0019] In the present invention, based on the total mass of the acrylic acid and glycidyl acrylate being 100%, the content of catalyst A is 0.8-1.2%, for example, it can be 0.8%, 0.85%, 0.9%, 0.95%, 1%, 1.05%, 1.1%, 1.15%, or 1.2%, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0020] In the present invention, based on the total mass of the acrylic acid and glycidyl acrylate being 100%, the content of the inhibitor is 0.05-0.2%, for example, it can be 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, or 0.2%, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0021] In the present invention, when the content of the inhibitor is too low, uncontrolled polymerization may occur during the preparation process. When the content is too high, it will not only cause waste of raw materials but also reduce the photocuring efficiency, resulting in insufficient crosslinking degree, thereby reducing the impact resistance and abrasion resistance of the obtained polyurethane material, and further affecting its shock absorption life.

[0022] Preferably, catalyst A includes any one or a combination of at least two of tetraethylammonium bromide, tetrabutylammonium bromide, tetrabutylammonium chloride, tetraethylammonium bromide, tetrabutylammonium hydrogensulfate, benzyltriethylammonium chloride, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, or tetradecyltrimethylammonium chloride.

[0023] Preferably, the inhibitor includes p-methoxyphenol (MEHQ) and / or tert-butyl-p-cresol (BHT).

[0024] In the present invention, a photosensitive photocurable monomer with specific bifunctional monohydroxy groups is prepared by reacting acrylic acid and glycidyl acrylate in a specific ratio, which can endow the obtained photocurable polyurethane resin with strong photocuring activity, high light conversion rate, and while greatly improving the preparation efficiency of the damping material, can preferably increase the crosslinking degree to form a network structure, thereby increasing its damping life and having excellent damping effect.

[0025] Exemplarily, the reaction equation for preparing the photosensitive photocurable monomer in the present invention is shown in Formula I: Formula I.

[0026] In the preparation process of the photosensitive photocurable monomer of the present invention, the reaction is stopped when the measured acid value is lower than 5 mgKOH / g, and the obtained photosensitive photocurable monomer has a monohydroxy structure with vinyl groups at both ends (the specific structure of which is not further explored whether it is A or B).

[0027] In the present invention, the acid value is measured by a conventional acid value measurement method. Further, as a preferred technical solution of the present invention, the acid value is measured by acid-base titration.

[0028] Preferably, the polyurethane prepolymer is prepared by reacting a polyester polyol and an isocyanate monomer.

[0029] Preferably, the molar ratio of the isocyanate monomer to the polyester polyol is (1.5 - 2):1, where (1.5 - 2) can be, for example, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95 or 2, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0030] Preferably, the polyester polyol includes any one or a combination of at least two of polyhexamethylene adipate, polycaprolactone diol or polybutylene adipate; more preferably, it is any one or a combination of at least two of polyhexamethylene adipate 1000, polycaprolactone diol 1000 or polybutylene adipate 1000.

[0031] In the present invention, by further optimizing the polyester polyol, the polyester polyol used is a highly crystalline polyol, and structures such as polyhexamethylene adipate and polycaprolactone diol have strong crystallinity, which can enhance the microphase separation of the polyurethane, making it have a strong buffering effect when resisting external impacts, avoiding damage to the obtained polyurethane material under repeated impact and stretching, and thereby increasing its damping life.

[0032] Preferably, the polyester polyol needs to be dehydrated before the reaction.

[0033] Preferably, the water removal treatment method includes vacuum water removal at 105-115 °C (such as 106 °C, 107 °C, 108 °C, 109 °C, 110 °C, 111 °C, 112 °C, 113 °C or 114 °C, etc.).

[0034] Preferably, the isocyanate monomer includes any one or a combination of at least two of toluene diisocyanate (TDI) monomer, diphenylmethane diisocyanate (MDI) monomer or hexamethylene diisocyanate (HDI) monomer.

[0035] Preferably, the TDI monomer includes any one or a combination of at least two of TDI-100, TDI-80 or TDI-65.

[0036] In the present invention, the isocyanate monomer is preferably TDI-100, which has a more regular structure. The polyurethane prepolymer prepared from it has a narrower molecular weight distribution, so that the impact resistance and abrasion resistance of the obtained polyurethane material are good, and thus the overall technical effect is better.

[0037] Preferably, the reaction is carried out under catalyst B.

[0038] Preferably, the catalyst B includes an organotin catalyst.

[0039] Preferably, the organotin catalyst includes dibutyltin dilaurate (DBTDL) and / or stannous octoate.

[0040] Preferably, based on the total mass of the polyester polyol and the isocyanate monomer being 100%, the content of the catalyst B is 0.05-0.2%, such as 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18% or 0.2%, and the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0041] Preferably, the reaction is carried out in an inert gas atmosphere.

[0042] Preferably, the inert gas includes any one or a combination of at least two of nitrogen, argon or helium.

[0043] Preferably, the preparation method of the polyurethane prepolymer specifically includes the following steps:

[0044] Under the action of catalyst B, the polyester polyol and the isocyanate monomer are reacted, and the reaction temperature is controlled not to exceed 35 °C, and the reaction is carried out until the hydroxyl value is lower than 5 mgKOH / g to obtain the polyurethane prepolymer.

[0045] In the preparation process of the polyurethane prepolymer of the present invention, under the action of catalyst B, the hydroxyl group (-OH) in the polyester polyol reacts with the isocyanate group (-NCO) in the isocyanate monomer; further, since the molar ratio of the isocyanate monomer to the polyester polyol is (1.5 - 2):1, that is, the amount of the isocyanate group > the amount of the hydroxyl group, a polyurethane prepolymer capped with an isocyanate group can be obtained.

[0046] Exemplarily, the reaction equation for preparing the polyurethane prepolymer in the present invention is shown in Formula II:

[0047] Formula II.

[0048] In the said Formula II, " " represents the polyester polyol, " " represents the isocyanate, and " " represents the polyurethane prepolymer.

[0049] Preferably, before adding the polyester polyol, the reaction temperature is controlled not to be higher than 15 °C, and more preferably 5 - 15 °C (for example, it can be 5 °C, 6 °C, 7 °C, 8 °C, 9 °C, 10 °C, 11 °C, 12 °C, 13 °C, 14 °C or 15 °C, etc.).

[0050] In the present invention, the hydroxyl value is measured by a conventional method in the art, including "GBT 7193.2 - 1987 Determination Method for Hydroxyl Value of Unsaturated Polyester Resins".

[0051] Preferably, after the reaction, a low-free treatment is carried out.

[0052] Preferably, the low-free treatment specifically includes subjecting the reaction solution after the reaction to vacuum distillation.

[0053] Preferably, the temperature of the vacuum distillation is 110 - 150 °C, for example, it can be 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C or 150 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the said range.

[0054] Preferably, the vacuum degree of the vacuum distillation is 0.1 - 2.0 mmHg, for example, it can be 0.1 mmHg, 0.3 mmHg, 0.5 mmHg, 0.8 mmHg, 1 mmHg, 1.2 mmHg, 1.5 mmHg, 1.8 mmHg or 2 mmHg, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the said range.

[0055] Preferably, the time for vacuum distillation is 6 - 8 h, for example, it can be 6 h, 6.5 h, 7 h, 7.5 h, 8 h or 8.5 h, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0056] Preferably, the free degree of isocyanate monomer in the polyurethane prepolymer is less than 0.1%.

[0057] In the present invention, the free degree of isocyanate monomer is determined by preparing an external standard curve using GC.

[0058] In the preparation process of the polyurethane prepolymer of the present invention, the polyester polyol reacts with the isocyanate monomer by adding it dropwise in batches slowly (it can be divided into 3 - 8 times, and the specific number of batches and the dropping rate are adjusted according to the actual temperature change), and during the reaction, the temperature is controlled by cooling with condensed water, so that the reaction temperature in the whole reaction system does not exceed 35°C. With the subsequent vacuum distillation post-treatment method, a small number of possible low-molecular-weight products or raw materials are eliminated, making the molecular weight distribution of the polyurethane material structure prepared very narrow. A narrow molecular weight distribution shows more isotropy when resisting external impacts, reduces internal losses, so that during its use, the heat generated inside is much lower than that of conventional materials, thereby improving its abrasion resistance performance and further enhancing its shock absorption life. When the reaction temperature is too high during the preparation process of the prepolymer, the molecular weight distribution of the polyurethane material structure prepared becomes wider, and during use, it cannot well reduce the internal heat generation, so it cannot well extend its shock absorption life.

[0059] Commercially available methods for preparing low-free prepolymers mainly use the diaphragm evaporation method. The polyurethane prepolymer prepared by this method is relatively convenient, but due to the high cost of the diaphragm evaporator equipment, the preparation cost is extremely high, and its preparation process cost is often equivalent to the material cost. In contrast, the present invention provides a method for preparing a low-free polyurethane prepolymer by combining a low-temperature process with vacuum distillation, which has a low preparation cost, and the dispersion coefficient of the polyurethane prepolymer prepared thereby is much lower than that of the polyurethane prepolymer prepared by the diaphragm evaporation method, enhancing its shock absorption effect.

[0060] In the second aspect, the present invention provides a method for preparing a photocurable polyurethane resin as described in the first aspect, and the preparation method includes the following steps:

[0061] Mix and react a photosensitive photocurable monomer with the polyurethane prepolymer, control the molar ratio of hydroxyl group to NCO to be 1:1, until the reaction NCO is less than 0.1%, to obtain the photocurable polyurethane resin.

[0062] In the preparation process of the photocurable polyurethane resin of the present invention, the isocyanate groups in the polyurethane prepolymer react with the hydroxyl groups in the photosensitive photocurable monomer, and the molar ratio of hydroxyl groups to NCO is controlled to be 1:1, so that the hydroxyl groups and isocyanate groups react completely, and a photocurable polyurethane resin containing acrylate groups is obtained.

[0063] Exemplarily, the reaction equation for preparing the photocurable polyurethane resin in the present invention is shown in Formula III:

[0064] Formula III.

[0065] In the said Formula III, " " represents the polyurethane prepolymer, " " represents the photosensitive photocurable monomer, and " " represents the photocurable polyurethane resin.

[0066] Preferably, the preparation method of the photocurable polyurethane resin specifically includes the following steps:

[0067] (1) Preparation of the photosensitive photocurable monomer

[0068] Mix acrylic acid, glycidyl acrylate, catalyst A and inhibitor, react at 100 - 110 °C for 3 - 6 h, and stop the reaction when the acid value is lower than 5 mgKOH / g to obtain the photosensitive photocurable monomer.

[0069] (2) Preparation of the polyurethane prepolymer

[0070] Under a nitrogen atmosphere, add isocyanate monomer and catalyst B to the reactor, stir and mix, and slowly add polyester polyol in batches when the temperature is 5 - 15 °C, keep the temperature not exceeding 35 °C, stop the reaction when the hydroxyl value is lower than 5 mgKOH / g, and carry out vacuum distillation on the reaction solution at a temperature of 110 - 150 °C, a vacuum degree of 0.1 - 2.0 mmHg, and a time of 6 - 8 h to obtain the polyurethane prepolymer, wherein the free degree of isocyanate is lower than 0.1%.

[0071] (3) Mix the photosensitive photocurable monomer described in step (1) with the polyurethane prepolymer described in step (2), control the molar ratio of hydroxyl groups to NCO to be 1:1 for reaction, and when NCO is lower than 0.1%, obtain the photocurable polyurethane resin.

[0072] In the third aspect, the present invention provides a photocurable polyurethane material, and the photocurable polyurethane material includes the photocurable polyurethane resin described in the first aspect.

[0073] Preferably, the photocurable polyurethane material includes the following components in parts by weight:

[0074] 60 - 80 parts by weight of the photocurable polyurethane resin, 10 - 20 parts by weight of the photocurable monomer, 2 - 8 parts by weight of the photocuring initiator, and 2 - 5 parts by weight of the filler as described in the first aspect.

[0075] In the photocurable polyurethane material of the present invention, the content of the photocurable polyurethane resin is 60 - 80 parts by weight, and for example, it can be 60 parts by weight, 62 parts by weight, 65 parts by weight, 68 parts by weight, 70 parts by weight, or 80 parts by weight, etc.

[0076] The content of the photocurable monomer is 10 - 20 parts by weight, and for example, it can be 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, or 20 parts by weight, etc.

[0077] The content of the photocuring initiator is 2 - 8 parts by weight, and for example, it can be 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, or 8 parts by weight, etc.

[0078] The content of the filler is 2 - 5 parts by weight, and for example, it can be 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, or 5 parts by weight, etc.

[0079] Preferably, the photocurable monomer described in the present invention is a conventional bifunctional monomer or trifunctional monomer in the art, including but not limited to any one or a combination of at least two of hexanediol diacrylate (HDDA), neopentyl glycol diacrylate (NPGDA), or trimethylolpropane triacrylate (TMPTA).

[0080] Preferably, the photocuring initiator of the present invention is a conventional product in the art, including but not limited to any one or a combination of at least two of photoinitiator 819, photoinitiator 1173, photoinitiator TPO, or photoinitiator 184.

[0081] Preferably, the filler includes carbon black.

[0082] Exemplarily, the preparation method of the photocurable polyurethane material provided by the present invention includes the following steps:

[0083] Mix the photocurable polyurethane resin, the photocurable monomer, the photocuring initiator, and the filler, and perform photocuring under ultraviolet light to obtain the photocurable polyurethane material.

[0084] Preferably, the exposure wavelength of the ultraviolet light is 365 - 380 nm, for example, it can be 365 nm, 368 nm, 370 nm, 372 nm, 375 nm, 378 nm or 380 nm, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0085] Preferably, the exposure energy of the ultraviolet light is 400 - 500 mJ / cm 2 , for example, it can be 400 mJ / cm 2 , 410 mJ / cm 2 , 420 mJ / cm 2 , 430 mJ / cm 2 , 440 mJ / cm 2 , 450 mJ / cm 2 , 460 mJ / cm 2 , 470 mJ / cm 2 , 480 mJ / cm 2 , 490 mJ / cm 2 or 500 mJ / cm 2 , as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0086] In the present invention, the exposure energy is limited. When it is higher than this range, the brittleness of the obtained polyurethane material is enhanced and the shock absorption effect is reduced.

[0087] The polyurethane material of the present invention is prepared from a polyurethane resin prepared with a photosensitive photocurable monomer having a specific double photofunctional group and single hydroxyl structure, which has strong photocuring activity. Since most shock-absorbing materials will be added with certain fillers, such as color powders for distinguishing colors, carbon black, pigments, etc., or some flame-retardant materials, such as flame retardants, or a certain amount of heat-conducting materials, such as micron-level alumina, aluminum nitride, boron nitride, etc., these materials will all affect the ultraviolet light and reduce the photocuring activity of the obtained polyurethane material. The polyurethane material of the present invention can use the self-made photosensitive photocurable monomer to compensate for the dilution of light by the filler as much as possible, thereby greatly improving the preparation efficiency of the obtained polyurethane material.

[0088] Fourthly, the present invention provides an application of the photocurable polyurethane material as described in the third aspect in automobiles and buildings.

[0089] The photocurable polyurethane material provided by the present invention can be well applied to the gaskets in various links of automobile shock absorption, so that it has a stronger shock absorption life.

[0090] Compared with the prior art, the present invention has at least the following beneficial effects:

[0091] The photosensitive photocurable monomer obtained by the reaction of acrylic acid and glycidyl acrylate in the present invention has a specific bifunctional monohydroxy structure, which can endow the obtained photocurable polyurethane resin with strong photocuring activity. While greatly improving the preparation efficiency of the damping material, it can also increase the crosslinking degree, and thus has excellent damping effect. Further, the photocurable polyurethane material prepared from the photocurable polyurethane resin provided by the present invention has a narrow molecular weight, low internal heat generation during use, so that its abrasion resistance can be effectively improved, and its damping life can be enhanced; at the same time, it also has a strong buffering effect and excellent impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 is the infrared spectrum of the photosensitive photocurable monomer obtained in Example 1;

[0093] Figure 2 is the infrared spectrum of the polyurethane prepolymer obtained in Example 1;

[0094] Figure 3 is the infrared spectrum of the photocurable polyurethane resin obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0095] The technical solution of the present invention will be further described below with reference to the drawings and specific embodiments. However, the following examples are only simple examples of the present invention, and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention is subject to the claims.

[0096] Unless otherwise specified, the raw materials and reagents used in the following examples, comparative examples and application examples are all commercially available. Some raw material information is as follows:

[0097] Polyhexamethylene adipate 1000: purchased from Huakai Resin hk-5112, Jining, Shandong;

[0098] Polycaprolactone diol 1000: purchased from Juren PCL1000, Hunan;

[0099] Polybutylene adipate 1000: purchased from Huafeng PE-T3010, Zhejiang;

[0100] Carbon black: purchased from Cabot MONARCH 1400.

[0101] Example 1

[0102] This example provides a photocurable polyurethane resin, and its preparation method includes the following steps:

[0103] (1) Preparation of photosensitive photocurable monomer

[0104] Acrylic acid (1.05 mol), glycidyl acrylate (1 mol), tetraethylammonium bromide (2 g) and inhibitor MEHQ (0.15 g) were mixed and reacted at 105 °C for 4.5 h. With an acid value of 3.3 mgKOH / g, the photosensitive photocurable monomer was obtained.

[0105] The obtained photosensitive photocurable monomer was tested by infrared spectroscopy. The test results are as Figure 1 shown. A relatively high characteristic absorption peak of alcoholic hydroxyl groups appeared at a wave number of 3550 cm -1 , indicating that the epoxy ring was opened to form free alcoholic hydroxyl groups. The characteristic absorption peak at a wave number of 1710 cm -1 was for the carbonyl group, and the characteristic absorption peaks at wave numbers of 1620 cm -1 and 1400 cm -1 indicated the presence of double bonds.

[0106] (2) Preparation of polyurethane prepolymer

[0107] Under a nitrogen atmosphere, TDI-100 monomer (2 mol) and dibutyltin dilaurate (0.7 g) were added to a reactor, stirred and mixed. At 10 °C, polyhexamethylene adipate 1000 (1 mol) was slowly added dropwise in four portions, keeping the temperature not exceeding 35 °C. The reaction was stopped when the hydroxyl value was measured to be less than 5 mgKOH / g. The reaction solution was subjected to vacuum distillation at a temperature of 130 °C, a vacuum degree of 1.0 mmHg, and a time of 7 h to obtain a polyurethane prepolymer, in which the free degree of TDI-100 was 0.08%.

[0108] The obtained polyurethane prepolymer was tested by infrared spectroscopy. The test results are as Figure 2 shown. There was no relatively high characteristic absorption peak of alcoholic hydroxyl groups at a wave number of 3500 cm -1 , and a characteristic absorption peak of NH appeared at 3250 cm -1 . There was an obvious characteristic absorption peak of NCO at 2260 cm -1 , indicating that the hydroxyl groups in the polyester polyol and the isocyanate monomer reacted to form an NCO-terminated prepolymer.

[0109] (3) The photosensitive photocurable monomer described in step (1) was mixed with the polyurethane prepolymer described in step (2), and the reaction was carried out by controlling the molar ratio of hydroxyl groups to NCO to be 1:1. When the NCO was measured to be less than 0.1%, the photocurable polyurethane resin was obtained.

[0110] The obtained photocurable polyurethane resin was tested by infrared spectroscopy. The test results are as Figure 3 shown. Compared with Figure 2 , it had a characteristic absorption peak of NCO at 2260 cm-1 It disappeared significantly, indicating that the isocyanate groups in the polyurethane prepolymer reacted with the hydroxyl groups in the photosensitive photocurable monomer.

[0111] Example 2

[0112] This example provides a photocurable polyurethane resin, and its preparation method includes the following steps:

[0113] (1) Preparation of the photosensitive photocurable monomer

[0114] Mix acrylic acid (1.02 mol), glycidyl acrylate (1 mol), tetrabutylammonium bromide (2 g) and inhibitor BHT (0.2 g), react at 110 °C for 3 h, with an acid value of 4.2 mgKOH / g, to obtain the photosensitive photocurable monomer.

[0115] (2) Preparation of the polyurethane prepolymer

[0116] Under a nitrogen atmosphere, add TDI-100 monomer (2 mol) and dibutyltin dilaurate (1.4 g) to the reactor, stir and mix, and slowly add polycaprolactone diol 1000 (1 mol) dropwise in three portions starting at 15 °C, keeping the temperature not exceeding 35 °C. Stop the reaction when the hydroxyl value is lower than 5 mgKOH / g. Carry out vacuum distillation on the reaction solution at a temperature of 110 °C, a vacuum degree of 0.1 mmHg, and a time of 8 h to obtain the polyurethane prepolymer, where the free TDI-100 content is 0.08%.

[0117] (3) Mix the photosensitive photocurable monomer described in step (1) with the polyurethane prepolymer described in step (2), control the molar ratio of hydroxyl group to NCO to be 1:1 for reaction, and when the NCO is lower than 0.1%, obtain the photocurable polyurethane resin.

[0118] Example 3

[0119] This example provides a photocurable polyurethane resin, and its preparation method includes the following steps:

[0120] (1) Preparation of the photosensitive photocurable monomer

[0121] Mix acrylic acid (1 mol), glycidyl acrylate (1 mol), tetraethylammonium bromide (2.2 g) and inhibitor MEHQ (0.2 g), react at 100 °C for 6 h, with an acid value of 4.4 mgKOH / g, to obtain the photosensitive photocurable monomer.

[0122] (2) Preparation of the polyurethane prepolymer

[0123] Under a nitrogen atmosphere, 3 mol of TDI-100 monomer and 5 g of dibutyltin dilaurate were added to a reactor, stirred and mixed. At 5°C, 2 mol of polybutylene adipate 1000 was slowly added dropwise in five portions, keeping the temperature not exceeding 35°C. The reaction was stopped when the hydroxyl value was lower than 5 mgKOH / g. The reaction solution was subjected to vacuum distillation at a temperature of 150°C, a vacuum degree of 2.0 mmHg, and a time of 6 h to obtain a polyurethane prepolymer, with the free TDI-100 content being 0.07%.

[0124] (3) Mix the photosensitive photocurable monomer described in step (1) with the polyurethane prepolymer described in step (2), and control the molar ratio of hydroxyl group to NCO to be 1:1 for reaction. When the NCO content is lower than 0.1%, the photocurable polyurethane resin is obtained.

[0125] Example 4

[0126] This example provides a photocurable polyurethane resin, which is different from Example 1 in that 1000 of neopentyl glycol polyphthalate (purchased from Zhejiang Huafeng HF-8211) with an equal molar amount is used to replace 1000 of polyhexylene adipate in step (2), and other raw materials, contents, and preparation methods are the same as those in Example 1.

[0127] Example 5

[0128] This example provides a photocurable polyurethane resin, which is different from Example 1 in that the temperature is maintained at 50 ± 3°C in step (2), and other raw materials, contents, and preparation methods are the same as those in Example 1.

[0129] Example 6

[0130] This example provides a photocurable polyurethane resin, which is different from Example 1 in that the TDI-100 monomer in step (2) is replaced with an equal mass of TDI-80, and other raw materials, contents, and preparation methods are the same as those in Example 1.

[0131] Example 7

[0132] This example provides a photocurable polyurethane resin, which is different from Example 1 in that the TDI-100 monomer in step (2) is replaced with an equal mass of TDI-65, and other raw materials, contents, and preparation methods are the same as those in Example 1.

[0133] Example 8

[0134] This embodiment provides a photocurable polyurethane resin, which is different from that of Example 1 in that the content of the inhibitor MEHQ in step (1) is adjusted from 0.15 g to 0.6 g, and the other raw materials, contents and preparation methods are the same as those of Example 1.

[0135] Comparative Example 1

[0136] This comparative example provides a photocurable polyurethane resin, which is different from that of Example 1 in that the photosensitive photocurable monomer is replaced with 2-hydroxyethyl acrylate (HEA), and the other raw materials, contents and preparation methods are the same as those of Example 1.

[0137] Application Example 1

[0138] This application example provides a photocurable polyurethane material, and its preparation method includes the following steps:

[0139] Mix 70 parts by weight of photocurable polyurethane resin (Example 1), 15 parts by weight of photocurable monomer HDDA, 5 parts by weight of photoinitiator 1173, and 3.5 parts by weight of carbon black to obtain a mixed solution. Introduce the mixed solution into a trough with a mold of 100*100*3 mm for exposure. Under the conditions of an exposure wavelength of 365 - 380 nm and an exposure energy of 400 - 500 mJ / cm 2 Perform photocuring to obtain the photocurable polyurethane material.

[0140] Application Example 2

[0141] This application example provides a photocurable polyurethane material, and its preparation method includes the following steps:

[0142] Mix 60 parts by weight of photocurable polyurethane resin (Example 1), 10 parts by weight of photocurable monomer NPGDA, 2 parts by weight of photoinitiator 184, and 2 parts by weight of carbon black to obtain a mixed solution. Introduce the mixed solution into a trough with a mold of 100*100*3 mm for exposure. Under the conditions of an exposure wavelength of 365 - 380 nm and an exposure energy of 400 - 500 mJ / cm 2 Perform photocuring to obtain the photocurable polyurethane material.

[0143] Application Example 3

[0144] This application example provides a photocurable polyurethane material, and its preparation method includes the following steps:

[0145] Mix 80 parts by weight of photocurable polyurethane resin (Example 1), 20 parts by weight of photocurable monomer TMPTA, 8 parts by weight of photoinitiator 819, and 5 parts by weight of carbon black to obtain a mixed solution. Introduce the mixed solution into a trough with a mold of 100*100*3 mm for exposure. Under the conditions of an exposure wavelength of 365 - 380 nm and an exposure energy of 400 - 500 mJ / cm2 Perform bottom light curing to obtain the light-cured polyurethane material.

[0146] Application Examples 4 - 10

[0147] The difference between Application Examples 4 - 10 and Application Example 1 is that the light-cured polyurethane resin (Example 1) in Application Example 1 is replaced with an equal mass of light-cured polyurethane resins (Examples 2 - 8), and other components, contents, and preparation methods are the same as those in Application Example 1.

[0148] Comparative Application Example 1

[0149] This Comparative Application Example 1 provides a light-cured polyurethane material. The difference between it and Application Example 1 is that the light-cured polyurethane resin (Example 1) in Application Example 1 is replaced with an equal mass of light-cured polyurethane resin (Comparative Example 1), and other components, contents, and preparation methods are the same as those in Application Example 1.

[0150] Perform performance tests on the above Application Examples 1 - 10 and Comparative Application Example 1. The test methods / standards are as follows:

[0151] (1) Impact resistance: Refer to GB / T 39814 - 2021, use a 50 g metal ball, and test the cracking height (mm) when the falling ball is at the center position;

[0152] (2) Abrasion resistance: Use a Taber abrasion machine, select CS - 10 rollers, set a load of 500 g, 60 revolutions per minute, and test the abrasion result after 200 revolutions:

[0153] Abrasion index = loss mass / 200 * 1000 (mg);

[0154] (3) Light curing efficiency (%): Refer to GB / T 6040 - 2019, select the characteristic absorption peak at 1380 - 1420 cm -1 double bond peak, select the reference peak at 1656 - 1730 cm -1 near carbonyl peak. Before curing, the test sample is a mixture. After curing, select a sample piece for the test sample. The test surface of the sample piece needs to be cleaned with alcohol first, and then pressed into a tablet for infrared testing.

[0155] The test results are shown in Table 1.

[0156] Table 1

[0157]

[0158] It can be seen from the test results that:

[0159] (1)As can be seen from Application Examples 1 to 10, when the photocurable polyurethane resin prepared by reacting a specific photosensitive polyurethane monomer with a polyurethane prepolymer of the present invention is applied to a photocurable polyurethane material, it can endow the material with excellent photocuring efficiency (65.44 - 80.16%), high impact resistance (the cracking height is not less than 200 mm), and high abrasion resistance. The comprehensive effect is excellent, which can effectively improve its shock absorption life and endow it with excellent shock absorption effect.

[0160] (2)As can be seen from the comparison between Application Example 1 and Application Example 6, Application Example 6 uses a non-specific polyester polyol of the present invention, and the impact resistance and abrasion resistance of the obtained photocurable polyurethane material are significantly reduced. This shows that by further selecting and optimizing the polyamine polyol in the preparation process of the photocurable polyurethane resin of the present invention, the obtained polyurethane resin can have better impact resistance and abrasion resistance when applied to the photocurable polyurethane material, which can effectively improve its shock absorption life and endow it with better shock absorption effect.

[0161] (3)As can be seen from the comparison between Application Example 1 and Application Example 7, the process temperature in the preparation process of the polyurethane prepolymer in the photocurable polyurethane resin of Application Example 7 is relatively high, resulting in a too wide molecular weight distribution. As a result, the impact resistance and abrasion resistance of the obtained polyurethane material are significantly reduced. This shows that by optimizing the process temperature of the polyurethane prepolymer in the preparation process of the photocurable polyurethane resin of the present invention, the impact resistance and abrasion resistance of the obtained polyurethane material can be significantly improved, thereby improving its shock absorption life and endowing it with better shock absorption effect.

[0162] (4)As can be seen from the comparison between Application Example 1 and Application Examples 8 and 9, TDI-80 and TDI-65 are used in Application Examples 8 and 9 respectively, and their regularity is slightly worse than that of TDI-100. Therefore, the molecular weight distribution of the products prepared is wider, and their impact resistance and abrasion resistance are slightly worse than those of Application Example 1. This shows that by further selecting and optimizing the isocyanate in the preparation process of the photocurable polyurethane resin of the present invention, better comprehensive performance can be obtained, thereby improving its shock absorption life and endowing it with better shock absorption effect.

[0163] (5)As can be seen from the comparison between Application Example 1 and Application Example 10, during the preparation process of the photocurable polyurethane resin, when the content of the inhibitor is too high, the photocuring effect will be reduced, resulting in insufficient crosslinking degree and a slight decrease in both impact resistance and abrasion resistance.

[0164] (6) It can be seen from the comparison between Application Example 1 and Comparative Application Example 1 that in Comparative Application Example 1, a HEA was used to replace the specific photosensitive type of photocurable monomer of the present invention, resulting in a significant reduction in the photocuring conversion efficiency, a substantial decrease in both the impact resistance and wear resistance, and an inability to effectively improve the shock absorption life of the resulting polyurethane material.

[0165] In summary, when the photocurable polyurethane resin prepared by reacting a specific photosensitive type of polyurethane monomer with a polyurethane prepolymer according to the present invention is applied to a photocurable polyurethane material, it can endow the material with excellent photocuring efficiency, high impact resistance, and high wear resistance, thereby effectively improving its shock absorption life and achieving excellent shock absorption effects.

[0166] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A photocurable polyurethane resin, characterized in that, The raw materials for preparing the photocurable polyurethane resin include a photosensitive photocurable monomer and a polyurethane prepolymer; The specific preparation method of the photosensitive photocurable monomer includes the following steps: Mix acrylic acid, glycidyl acrylate, catalyst A and inhibitor, and react at 100 - 110 °C for 3 - 6 h to obtain the photosensitive photocurable monomer; The molar ratio of acrylic acid to glycidyl acrylate is (1.02 - 1.05):1; Based on the total mass of acrylic acid and glycidyl acrylate being 100%, the content of catalyst A is 0.8 - 1.2%; Based on the total mass of acrylic acid and glycidyl acrylate being 100%, the content of inhibitor is 0.05 - 0.2%; The preparation method of the polyurethane prepolymer specifically includes the following steps: Under the action of catalyst B, react polyester polyol with isocyanate monomer, control the reaction temperature not higher than 35 °C, and react until the hydroxyl value is lower than 5 mgKOH / g to obtain the polyurethane prepolymer; The polyester polyol includes any one or a combination of at least two of polyhexamethylene adipate, polycaprolactone diol or polybutylene adipate; The isocyanate monomer is TDI - 100.

2. The photocurable polyurethane resin according to claim 1, wherein In the preparation method of the polyurethane prepolymer, the molar ratio of the isocyanate monomer to the polyester polyol is (1.5 - 2):1; The catalyst B includes an organotin catalyst.

3. The photocurable polyurethane resin according to claim 1, characterized in that, After the reaction of the polyester polyol and the isocyanate monomer, low - free treatment is carried out; The low - free treatment specifically includes subjecting the reaction solution after the reaction to vacuum distillation; The free degree of the isocyanate monomer in the polyurethane prepolymer is lower than 0.1%.

4. A method for preparing a photocurable polyurethane resin according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: Mix and react the photosensitive photocurable monomer with the polyurethane prepolymer, control the molar ratio of hydroxyl group to NCO to be 1:1, and react until the NCO is lower than 0.1% to obtain the photocurable polyurethane resin.

5. A photocurable polyurethane material, characterized in that, The photocurable polyurethane material includes the photocurable polyurethane resin according to any one of claims 1 - 3.

6. The photocurable polyurethane material according to claim 5, characterized in that, The photocurable polyurethane material includes the following components in parts by weight: 60 - 80 parts by weight of the photocurable polyurethane resin according to any one of claims 1 - 3, 10 - 20 parts by weight of photocurable monomer, 2 - 8 parts by weight of photocurable initiator, 2 - 5 parts by weight of filler; The photocurable monomer includes any one or a combination of at least two of HDDA, NPGDA or TMPTA; The filler includes carbon black.

7. The application of the photocurable polyurethane material according to claim 5 in automobiles and buildings.

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