Preparation method of aromatic polyurethane acrylate

Abstract

The invention relates to the technical field of organic synthesis, in particular to a preparation method of aromatic polyurethane acrylate, which comprises the following steps: S1, adding toluene diisocynate and dibutyltin dilaurate into a reactor, introducing dry air, adding octyldodecanol, and stirring for reaction to obtain a prepolymer; and S2, adding dibutyltin dilaurate and p-methoxyphenol into the prepolymer, then adding hydroxyethyl acrylate, carrying out a stirring reaction, cooling and filtering to obtain the aromatic polyurethane acrylate. The invention provides a method for preparing aromatic polyurethane acrylate, and the product, as an oligomer of an ultraviolet curing optical fiber coating, has the advantages of good flexibility, high curing rate, good solvent resistance, good wear resistance and the like, also has excellent yellowing resistance, also has very excellent weather resistance while ensuring high mechanical properties, and is suitable for industrial production. And the market prospect is wide.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing aromatic polyurethane acrylate. Background Art

[0002] As a high-performance polymer, polyurethane acrylate (PUA) material has the advantages of good flexibility, high curing rate, excellent solvent resistance and wear resistance. It is increasingly widely used in new energy, transportation, medical equipment, consumer electronics and daily necessities. In the field of new energy, polyurethane acrylate is widely used in the encapsulation and protective layer of solar panels, wind power equipment, etc. due to its excellent insulation performance and good processability, effectively improving the overall performance and service life of the equipment. In the transportation industry, PUA materials, as key components of coatings and adhesives, significantly improve the weather resistance, impact resistance and aesthetics of vehicle shells, and promote the lightweight and environmental protection process of the automotive industry. In addition, in the field of medical devices, polyurethane acrylate has become an ideal material for manufacturing high-end medical devices such as medical catheters and artificial organs due to its good biocompatibility and chemical resistance, providing strong support for the development of medical technology. At the same time, in the field of consumer electronics, PUA materials are also widely used in the shells and display screen protective coatings of electronic products such as smartphones and tablets, which not only enhances the durability of the products, but also improves the user experience.

[0003] In the prior art, traditional aromatic polyurethane acrylates are prone to photooxidation when exposed to ultraviolet light for a long time, resulting in yellowing on the surface of the material, which not only affects the appearance of the product, but may also further affect the light transmittance and mechanical properties of the product. Long-term exposure to ultraviolet light can also cause the breakage and rearrangement of chemical bonds inside the material, leading to photodegradation of the material, thereby reducing the overall performance and service life of the material. In addition, when preparing aromatic polyurethane acrylates, the high mechanical properties of the material often sacrifice a certain degree of weather resistance, and vice versa. Summary of the invention

[0004] In order to solve the problems mentioned in the above background technology, the present invention provides a method for preparing aromatic polyurethane acrylate.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing aromatic polyurethane acrylate comprises the following steps:

[0007] S1. Add toluene diisocyanate and dibutyltin dilaurate into the reactor, stir for 10 minutes to mix evenly, then introduce dry air, maintaining an air flow rate of 0.2-0.3m 3 / h, adding octyldodecanol, controlling the temperature, stirring and reacting to obtain a prepolymer containing an isocyanate group;

[0008] The reaction equation is:

[0009]

[0010] In step S1, toluene diisocyanate (TDI) and octyl dodecanol react under the action of catalyst dibutyltin dilaurate (DBTDL). As an aromatic diisocyanate, the isocyanate group (-NCO) in the molecular structure of TDI is highly reactive. When in contact with the hydroxyl group (-OH) of octyl dodecanol, an addition polymerization reaction will occur to form a carbamate bond (-NHCOO-), while releasing carbon dioxide. In this process, DBTDL, as a catalyst, can effectively reduce the activation energy of the reaction, accelerate the reaction process, and ensure the efficient generation of the prepolymer.

[0011] S2. Adding a catalyst, dibutyltin dilaurate, and a polymerization inhibitor, p-methoxyphenol, to the prepolymer, and then adding hydroxyethyl acrylate, controlling the temperature, stirring to react, cooling, and filtering to obtain aromatic polyurethane acrylate.

[0012] The reaction equation is:

[0013]

[0014] in,

[0015] R1:CH3(CH2) 19 -R2: R3:

[0016] In step S2, the remaining isocyanate groups in the prepolymer react with the hydroxyl groups of hydroxyethyl acrylate (HEA) in the presence of DBTDL and inhibitor p-methoxyphenol (MEQP) to form new urethane bonds, and at the same time, the acrylic acid groups (C=C double bonds) of HEA are introduced into the polyurethane chain.

[0017] Furthermore, in step S1, the reaction temperature is 25-45° C., and the stirring speed is 50-100 rpm.

[0018] Furthermore, after stirring the reaction for 2 hours in step S1, sampling is performed to detect the content of isocyanate groups. When 7.86%≤NCO≤8.13%, the prepolymerization reaction is considered to be completed. If the requirement is not met, sampling is performed every 1 hour until the requirement is met.

[0019] Furthermore, in step S2, the reaction temperature is 55-75°C, the stirring speed is 100-200 rpm, and the temperature is reduced to 55-65°C.

[0020] Furthermore, after stirring the reaction for 2 hours in step S2, sampling is performed to detect the content of isocyanate groups. When NCO ≤ 0.06%, the reaction is considered to be completed. If the requirement is not met, sampling is performed every 1 hour until the requirement is met.

[0021] Furthermore, the molar ratio of the reactants octyl dodecanol: toluene diisocyanate: hydroxyethyl acrylate is 1:(1.1-1.2):1.

[0022] Furthermore, the amount of dibutyltin dilaurate used in step S1 is 0.03-0.05wt% of the total mass of the reactants, and the amount of dibutyltin dilaurate used in step S2 is 0.07-0.08wt% of the total mass of the reactants.

[0023] Furthermore, the amount of p-methoxyphenol used in step S2 is 0.07-0.09wt% of the total mass of the reactants.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The polyurethane molecular chain prepared by the present invention contains a large amount of carbamate bonds (-NHCOO-), which has a certain degree of rotational freedom, so that the polyurethane chain segments can undergo elastic deformation when subjected to external forces, thereby giving the material good elasticity. Octyldodecanol is a long-chain alcohol, and its introduction significantly increases the length and flexibility of the polyurethane molecular chain. The long-chain structure can more effectively disperse and absorb energy when subjected to external forces, reduce stress concentration, and thus improve the flexibility and impact resistance of the material. The polyurethane molecular chains interact through non-covalent bonds such as hydrogen bonds to form a three-dimensional network structure, which allows the segments to move freely within a certain range while maintaining the strength of the material, further enhancing the flexibility of the material.

[0026] 2. The aromatic ring structure in the aromatic polyurethane acrylate prepared by the present invention has high stability and is not easily affected by external factors such as ultraviolet rays and chemical changes that lead to yellowing. In addition, the hard surface layer formed after the acrylic acid group is cured provides additional wear protection for the coating. The combination of the elasticity of polyurethane and the hardness of the acrylic acid group enables the coating to simultaneously exhibit good elasticity and wear resistance when subjected to external forces. Therefore, the obtained aromatic polyurethane acrylate has both weather resistance and good mechanical properties.

[0027] 3. The three-dimensional network structure formed after curing of polyurethane acrylate is highly dense, which can effectively block the penetration and diffusion of solvent molecules, making it difficult for solvent molecules to destroy the stability of this structure, thereby improving the solvent resistance of the coating. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market.

[0030] The NCO value is tested in accordance with the method in GB / T 12009.4-2016 "Aromatic isocyanates for the production of plastic polyurethanes Part 4: Determination of isocyanate content".

[0031] Example 1

[0032] A method for preparing aromatic polyurethane acrylate comprises the following steps:

[0033] According to the amount of substances, octyl dodecanol: toluene diisocyanate: hydroxyethyl acrylate = 1:1.1:1, 191.60g toluene diisocyanate and 0.25g dibutyltin laurate were added into a four-necked flask with a thermometer and an air connection tube. After stirring for 10 minutes and mixing evenly, the air flow rate was 0.2m 3 / h, add 298.56g of octyldodecanol into the flask in portions, control the temperature of the material in the flask to maintain at 25℃ for reaction, stir and react for 2h, take a sample to detect the NCO value = 7.93%, add 0.42g of dibutyltin dilaurate and 0.42g of p-methoxyphenol into the flask in sequence, and then add 116.15g of hydroxyethyl acrylate in portions, control the temperature of the material in the flask to maintain at 55℃ for reaction, stir and react for 2h, take a sample to detect the NCO value = 0.02%, the reaction is completed, cool to 60℃, filter under pressure to obtain a colorless and transparent aromatic polyurethane acrylate product.

[0034] Example 2

[0035] According to the amount of substances, octyl dodecanol: toluene diisocyanate: hydroxyethyl acrylate = 1:1.1:1, 191.55g toluene diisocyanate and 0.24g dibutyltin laurate were added into a four-necked flask with a thermometer and an air connection tube. After stirring for 10 minutes and mixing evenly, the air flow rate was 0.2m 3 / h, add 298.55g of octyldodecanol into the flask in portions, control the temperature of the material in the flask to maintain at 30°C for reaction, stir and react for 2h, take a sample to detect the NCO value = 7.93%, add 0.41g of dibutyltin dilaurate and 0.41g of p-methoxyphenol into the flask in sequence, and then add 116.16g of hydroxyethyl acrylate in portions, control the temperature of the material in the flask to maintain at 60°C for reaction, stir and react for 2h, take a sample to detect the NCO value = 0.04%, the reaction is completed, cool to 55°C, filter under pressure to obtain a colorless and transparent aromatic polyurethane acrylate product.

[0036] Example 3

[0037] According to the amount of substances, octyl dodecanol: toluene diisocyanate: hydroxyethyl acrylate = 1:1.2:1, 209.19g toluene diisocyanate and 0.25g dibutyltin laurate were added into a four-necked flask with a thermometer and an air connection tube, and stirred for 10 minutes to mix well. The air flow rate was 0.3m 3 / h, add 298.60g of octyldodecanol into the flask in portions, control the temperature of the material in the flask to maintain at 30°C for reaction, stir and react for 2h, take a sample to detect the NCO value = 8.01%, add 0.44g of dibutyltin dilaurate and 0.44g of p-methoxyphenol into the flask in sequence, and then add 116.12g of hydroxyethyl acrylate in portions, control the temperature of the material in the flask to maintain at 65°C for reaction, stir and react for 2h, take a sample to detect the NCO value = 0.04%, the reaction is completed, cool to 60°C, filter under pressure to obtain a colorless and transparent aromatic polyurethane acrylate product.

[0038] Example 4

[0039] According to the amount of substances, octyl dodecanol: toluene diisocyanate: hydroxyethyl acrylate = 1:1.1:1, 191.60g toluene diisocyanate and 0.25g dibutyltin laurate were added into a four-necked flask with a thermometer and an air connection tube. After stirring for 10 minutes and mixing evenly, the air flow rate was 0.3m 3 / h, add 298.55g of octyldodecanol into the flask in portions, control the temperature of the material in the flask to maintain at 40°C for reaction, stir and react for 2h, take a sample to detect the NCO value = 7.93%, add 0.41g of dibutyltin dilaurate and 0.41g of p-methoxyphenol into the flask in sequence, and then add 116.18g of hydroxyethyl acrylate in portions, control the temperature of the material in the flask to maintain at 70°C for reaction, stir and react for 2h, take a sample to detect the NCO value = 0.05%, the reaction is completed, cool to 65°C, filter under pressure to obtain a colorless and transparent aromatic polyurethane acrylate product.

[0040] Example 5

[0041] According to the amount of substances, octyl dodecanol: toluene diisocyanate: hydroxyethyl acrylate = 1:1.1:1, 191.58g toluene diisocyanate and 0.24g dibutyltin laurate were added into a four-necked flask with a thermometer and an air connection tube. After stirring for 10 minutes and mixing evenly, the air flow rate was 0.3m 3 / h, add 298.58g of octyldodecanol into the flask in portions, control the temperature of the material in the flask to maintain at 40°C for reaction, stir and react for 2h, take a sample to detect the NCO value = 8.11%, add 0.42g of dibutyltin dilaurate and 0.42g of p-methoxyphenol into the flask in sequence, and then add 116.16g of hydroxyethyl acrylate in portions, control the temperature of the material in the flask to maintain at 70°C for reaction, stir and react for 2h, take a sample to detect the NCO value = 0.01%, the reaction is completed, cool to 60°C, filter under pressure to obtain a colorless and transparent aromatic polyurethane acrylate product.

[0042] Example 6

[0043] According to the amount of substances, octyl dodecanol: toluene diisocyanate: hydroxyethyl acrylate = 1:1.1:1, 191.55g toluene diisocyanate and 0.25g dibutyltin laurate were added into a four-necked flask with a thermometer and an air connection tube, and stirred for 10 minutes to mix well. The air flow rate was 0.3m 3 / h, add 298.54g of octyldodecanol into the flask in portions, control the temperature of the material in the flask to maintain at 45°C for reaction, stir the reaction for 2h, take a sample to detect the NCO value = 7.96%, add 0.41g of dibutyltin dilaurate and 0.41g of p-methoxyphenol into the flask in sequence, and then add 116.19g of hydroxyethyl acrylate in portions, control the temperature of the material in the flask to maintain at 75°C for reaction, stir the reaction for 2h, take a sample to detect the NCO value = 0.02%, the reaction is completed, cool to 55°C, filter under pressure to obtain a colorless and transparent aromatic polyurethane acrylate product.

[0044] Comparative Example 1

[0045] The difference between this comparative example and Example 1 is that hydroxyethyl acrylate is not added, and the remaining steps are the same as those in Example 1.

[0046] Comparative Example 2

[0047] The difference between this comparative example and Example 2 is that diphenylmethane diisocyanate (MDI) is used instead of toluene diisocyanate (TDI), and the remaining steps are the same as those in Example 2.

[0048] Methylene diphenyl diisocyanate

[0049] At 25° C., the viscosity (Brookfield, digital viscometer DV3TRVTJO model) and refractive index (Abbe refractometer, WAY-3S) of Examples 1-6 were measured. The results are shown in Table 1:

[0050] Table 1. Viscosity and refractive index results of Examples 1-6

[0051]

[0052]

[0053] Elasticity test: 5 samples were selected from Examples 1-6 and placed under standard temperature and humidity conditions for 24 hours to eliminate internal stress. The stress and strain of the samples during the stretching process were measured using a dynamic mechanical analyzer (DMA). The tensile test was performed at room temperature at a stretching rate of 5% / min, and the stress-strain curve was recorded. The slope of the initial stage of the curve was the elastic modulus, and the elongation at break (i.e., the strain value when the sample broke) was calculated. The results are shown in Table 2:

[0054] Table 2. Elasticity test results of Examples 1-6

[0055] serial number Elastic modulus (MPa) Elongation at break (%) Example 1 154 344 Example 2 153 371 Example 3 147 387 Example 4 143 353 Example 5 158 358 Example 6 142 375 Comparative Example 1 127 314 Comparative Example 2 141 307

[0056] Weather resistance test: The samples prepared in Examples 1-6 were placed in an accelerated aging test chamber and the UV irradiation intensity was set to 1 W / m 2 , the temperature is 60℃, and the aging is 48h to simulate the aging in the actual use environment. Observe whether there are cracks on the surface of the sample, and use a colorimeter to measure the color difference of the sample before and after aging. The results are shown in Table 3:

[0057] Table 3. Weathering resistance test results of Examples 1-6

[0058] serial number Color difference change (ΔE) Crack situation Example 1 0.3±0.1 No cracks Example 2 0.4±0.1 No cracks Example 3 0.3±0.1 No cracks Example 4 0.3±0.1 No cracks Example 5 0.3±0.1 No cracks Example 6 0.3±0.1 No cracks Comparative Example 1 0.6±0.1 Slight cracks Comparative Example 2 0.8±0.1 Slight cracks

[0059] Mechanical property test: The samples in Examples 1-6 were placed under standard temperature and humidity conditions for 24 h, and a universal material testing machine (XL-AS100 / AS300) was used to record the tensile strength at a tensile rate of 10 mm / min and the compressive strength at a compression rate of 5 mm / min. The results are shown in Table 4:

[0060] Table 4. Mechanical properties test results of Examples 1-6

[0061]

[0062]

[0063] As can be seen from Table 1, the viscosity and refractive index of Examples 1-6 all show a certain range of variation. The change in viscosity is mainly affected by the length of the molecular chain, the degree of branching and the degree of crosslinking, while the refractive index is closely related to the chemical composition and molecular structure of the material. The viscosity of Comparative Example 1 was significantly reduced because hydroxyethyl acrylate was not added, indicating that the addition of hydroxyethyl acrylate increased the length of the molecular chain or the degree of crosslinking, thereby increasing the viscosity. Comparative Example 2 used diphenylmethane diisocyanate instead of toluene diisocyanate, and the viscosity also decreased, which may be due to the different effects of different isocyanates on the molecular chain structure.

[0064] As shown in Table 2, elastic modulus and elongation at break are important indicators for measuring the elastic properties of materials. The elastic modulus of Examples 1-6 fluctuates within a certain range, while the elongation at break is generally high, indicating that the prepared aromatic polyurethane acrylate has good elasticity and toughness. Comparative Example 1 has no addition of hydroxyethyl acrylate, so the elastic modulus and elongation at break are both reduced, indicating that the addition of hydroxyethyl acrylate helps to improve the elasticity and toughness of the material. Comparative Example 2 uses different isocyanates, and the elastic modulus does not change much, but the elongation at break is significantly reduced, indicating that the type of isocyanate has a greater impact on the toughness of the material.

[0065] As shown in Table 3, all examples showed no cracks after the accelerated aging test, and the color difference changed slightly, indicating that the prepared aromatic polyurethane acrylate had good weather resistance. Comparative Examples 1 and 2 both showed slight cracks after aging, and the color difference changed greatly, indicating that the addition of hydroxyethyl acrylate and the selection of isocyanate had an important influence on the weather resistance of the material. This may be related to the fact that the functional groups in the molecules of hydroxyethyl acrylate and toluene diisocyanate can improve the stability and weather resistance of the material.

[0066] As shown in Table 4, the tensile strength and compressive strength of Examples 4 and 6 are both high, indicating that the materials prepared in these two examples have good mechanical properties. Since no hydroxyethyl acrylate is added to Comparative Example 1, the tensile strength and compressive strength are significantly reduced, which again shows that the addition of hydroxyethyl acrylate plays an important role in improving the mechanical properties of the material. Comparative Example 2 uses different isocyanates, and the tensile strength is improved, but the compressive strength does not change much, indicating that the type of isocyanate has a great influence on the tensile properties of the material.

[0067] In summary, the aromatic polyurethane acrylates prepared in Examples 1-6 have relatively high viscosity, elasticity, toughness and mechanical properties, and have good weather resistance while improving material stability.

[0068] In the description of the specification, the description with reference to the terms "preparation example", "embodiment", "various embodiments" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or preparation example are included in at least one embodiment or preparation example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or preparation example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or preparation examples in a suitable manner.

[0069] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing an aromatic polyurethane acrylate, characterized in that: The following steps are involved: S1, adding toluene diisocyanate and dibutyltin dilaurate into a reactor, introducing dry air, adding octyl dodecanol, controlling the temperature, stirring and reacting to obtain a prepolymer containing an isocyanate group; S2. Add dibutyltin dilaurate and p-methoxyphenol to the prepolymer, and then add hydroxyethyl acrylate, control the temperature, stir to react, cool down, filter, and obtain aromatic polyurethane acrylate.

2. The method for preparing the aromatic polyurethane acrylate according to claim 1, characterized in that: In step S1, the reaction temperature is 25-45° C., and the stirring speed is 50-100 rpm.

3. The method for preparing the aromatic polyurethane acrylate according to claim 1, characterized in that: After stirring the reaction for 2 hours in step S1, sampling is performed to detect the content of isocyanate groups. When 7.86%≤NCO≤8.13%, the prepolymerization reaction is considered to be completed. If the requirement is not met, sampling is performed every 1 hour until the requirement is met.

4. The method for preparing the aromatic polyurethane acrylate according to claim 1, characterized in that: In step S2, the reaction temperature is 55-75°C, the stirring speed is 100-200 rpm, and the temperature is reduced to 55-65°C.

5. The method for preparing the aromatic polyurethane acrylate according to claim 1, characterized in that: After stirring the reaction for 2 hours in step S2, sampling is performed to detect the content of isocyanate groups. When NCO ≤ 0.06%, the reaction is considered to be complete. If the requirement is not met, sampling is performed every 1 hour until the requirement is met.

6. The method for preparing the aromatic polyurethane acrylate according to claim 1, characterized in that: The molar ratio of the reactants octyl dodecanol: toluene diisocyanate: hydroxyethyl acrylate is 1: (1.1-1.2):

1.

7. The method for preparing the aromatic polyurethane acrylate according to claim 1, characterized in that: The amount of dibutyltin dilaurate used in step S1 is 0.03-0.05wt% of the total mass of the reactants, and the amount of dibutyltin dilaurate used in step S2 is 0.07-0.08wt% of the total mass of the reactants.

8. The method for preparing the aromatic polyurethane acrylate according to claim 1, characterized in that: The amount of p-methoxyphenol used in step S2 is 0.07-0.09wt% of the total mass of the reactants.

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