Polyurethane coating having hydrophobic and multi-curing properties and method for preparing the same

Abstract

The application discloses a polyurethane coating with hydrophobicity and multiple curing performance and a preparation method thereof, and relates to the field of polyurethane coatings. Unsaturated polyurethane prepolymer containing NCO end groups is prepared by taking aliphatic diisocyanate and unsaturated dihydric alcohol as raw materials, then a hydroxyl-terminated silane coupling agent synthesized by a mercapto double bond reaction is added for sealing, and a series of unsaturated polyurethane with silane end groups is obtained by reaction, which can be used for preparing the polyurethane coating with hydrophobicity and multiple curing performance. The polyurethane with a carbon chain containing double bonds as a main chain and silane as end groups is synthesized, the surface of the coating is rapidly hardened by ultraviolet light, the end group silane is rapidly migrated to the surface, the coating interior is crosslinked by multiple curing, and the hydrophobicity, adhesion and surface strength of the coating are effectively improved, so that the polyurethane coating has potential application prospects in the fields of buildings, automobiles, aerospace and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular material and coating technology, and particularly relates to a polyurethane coating with hydrophobicity and multiple curing performance and a preparation method thereof. BACKGROUND

[0002] Polyurethane is generally a block copolymer obtained by polyaddition reaction of polyol compound and isocyanate compound. As a kind of coating, polyurethane coating has been widely applied in the fields of industry, agriculture, transportation and aerospace, etc. due to its simple construction, recyclability, high gloss, excellent decorative performance, strong wear resistance, good adhesion, good weather resistance, corrosion resistance and mechanical properties.

[0003] In recent years, the development of super-hydrophobic polyurethane coating has attracted extensive attention, and it has great potential in the applications of anti-fouling self-cleaning, oil spill treatment, protective coating, self-healing material and sensor, etc. It has been reported that polyurethane molecules with a large number of -Si-O-Si- bond structures in the main chain are prepared by mixing polysilane containing dihydroxyl or polyhydroxyl with other polyols, and then reacting with isocyanate. The phase separation of polysilane (PDMS) and isocyanate segment promotes the migration of the -Si-O-Si- bond structure in the main chain to the surface of the coating, and the hydrophobicity and wear resistance of the coating are endowed by the hydrophobicity of the structure. However, the introduction of a large amount of polysilane into the polyurethane main chain, although it is beneficial to the migration of silicon atoms to the surface of the coating, but it also inevitably has an adverse effect on the performance of the coating matrix (such as adhesion and mechanical properties).

[0004] Another method for improving the hydrophobicity of the coating is to introduce silane coupling agents with active hydrogen, such as mercapto silane and amino silane (KH550), at both ends of the polyurethane molecular chain. In this method, the silane introduced at the end of the polyurethane can be cross-linked by hydrolysis to complete the wet curing and form a silica-like structure in the coating. However, due to the small content of silane coupling agent, the silica-like structure is mostly uniformly embedded in the polymer matrix to form a hybrid material, and it cannot migrate to the surface. Therefore, the improvement of the contact angle and surface wear resistance of this kind of polyurethane coating is limited. SUMMARY

[0005] In view of the problems of poor surface hydrophobicity, insufficient adhesion or large coating viscosity and difficult to flow of the existing polyurethane coating, the present application provides a polyurethane coating with hydrophobicity and multiple curing performance and a preparation method thereof. The coating is made of end-silane unsaturated polyurethane as the main raw material.

[0006] The technical scheme of the present application is as follows:

[0007] A terminal silane unsaturated polyurethane is prepared by the following method:

[0008] S1: Preparation of terminal hydroxyl silane

[0009] The hydroxyl-containing olefin compound, mercapto silane coupling agent, and catalyst are mixed and stirred at 70°C under nitrogen protection for 7h to obtain the terminal hydroxyl silane.

[0010] The hydroxyl-containing olefin compound is selected from hydroxyethyl acrylate, allyl alcohol, etc.

[0011] The mercapto silane coupling agent is γ-mercaptopropyl trimethoxysilane.

[0012] The catalyst is azobisisobutyronitrile.

[0013] The mass ratio of the hydroxyl-containing olefin compound, mercapto silane coupling agent, and catalyst is preferably 3.7-7.4:12.5:0.2.

[0014] S2: Preparation of terminal silane unsaturated polyurethane

[0015] The fatty diisocyanate, unsaturated diol, and catalyst are dissolved in a solvent and stirred at 50°C under dry nitrogen for 2h to obtain an unsaturated polyurethane prepolymer containing a terminal -NCO group, and the terminal hydroxyl silane prepared in S1 is added and reacted at 60°C for 1h, and then cooled to room temperature to obtain the terminal silane unsaturated polyurethane (which can be directly used for the preparation of subsequent coatings).

[0016] The fatty diisocyanate is selected from one of hexamethylene diisocyanate and isophorone diisocyanate.

[0017] The unsaturated diol is cis-2-butene-1,4 diol.

[0018] The catalyst is dibutyl tin dilaurate.

[0019] The solvent is selected from anhydrous acetone or N,N-dimethylformamide.

[0020] The mass ratio of the fatty diisocyanate, unsaturated diol, catalyst, and terminal hydroxyl silane is preferably 5:1.308-2.181:0.025:2.

[0021] The molar ratio of isocyanate groups (-NCO) to hydroxyl groups (-OH) in the reaction raw materials, i.e., the value of R, is preferably in the range of 1.2-2.

[0022] The terminal silane unsaturated polyurethane described in the present application can be used to prepare a polyurethane coating having hydrophobicity and multiple curing properties.

[0023] Therefore, the application further relates to a polyurethane coating with hydrophobicity and multiple curing performance, which is prepared from end-silane unsaturated polyurethane and benzoin dimethyl ether.

[0024] Specific coating preparation methods are as follows: the end-silane unsaturated polyurethane and the benzoin dimethyl ether are mixed, stirred at 60 DEG C for 30 minutes, poured into a dry glass dish, irradiated under a UV lamp, and then placed in an oven to be cured into a film;

[0025] The mass ratio of the benzoin dimethyl ether in the raw material is 2.2-2.3%;

[0026] The UV lamp irradiation time is 15-20 minutes;

[0027] The oven curing conditions are 80 DEG C and 30 minutes.

[0028] The polyurethane coating with hydrophobicity and multiple curing performance has the following characteristics.

[0029] The coating has the characteristics of multiple curing, hydrophobic surface, high surface hardness and good adhesion, wherein the multiple curing includes but is not limited to thermal curing, UV curing and moisture curing; the hydrophobic surface is formed by surface curing of the coating, and the water contact angle of the surface can be greater than 120 DEG; the high surface hardness is also formed by surface curing of the coating, and the surface hardness can be greater than 4H; and the good adhesion is achieved by constructing a gradient crosslinking structure of the coating, and the adhesion to the glass surface can be greater than 5A.

[0030] The application has the following beneficial effects.

[0031] 1. The polyurethane coating has the characteristics of low viscosity before curing, high surface hardness and good adhesion after curing, and can be implemented in the spraying of various complex types of products.

[0032] 2. The application develops polyurethane multiple curing with different reaction principles. The system is quickly shaped or reaches "surface dry" by using light curing, and the shadow or bottom layer is completely cured by using thermal reaction or moisture reaction to achieve "real dry", so that the overall curing of the shape-retaining coating is realized.

[0033] 3. The polyurethane coating can promote the migration of silane to the surface of the coating by the rapid "surface dry" of the coating, form a gradient distribution of silicon atoms on the surface of the coating, and endow the coating surface with good hydrophobicity and hardness.

[0034] 4. The polyurethane coating can realize the combination of the properties of the coating surface, such as hydrophobicity, hardness and good adhesion to the substrate, by controlling the curing degree of the coating at different depths.

[0035] 5. The polyurethane coating of the present invention has the advantages of simple preparation process, low reaction temperature, low viscosity and low cost, and has potential application prospects in the fields of construction, automobiles, aerospace and other fields. Attached Figure Description

[0036] Figure 1 : Schematic diagram of the reaction route for preparing terminal silane unsaturated polyurethane according to the present invention.

[0037] Figure 2 Fourier transform infrared spectra of hydroxysilane coupling agents in Examples 1-4.

[0038] Figure 3 Example 3: Fourier transform infrared spectra of unsaturated polyurethane prepolymer and silane-terminated unsaturated polyurethane.

[0039] Figure 4 Example 3: Elemental distribution of silicon from the surface to the interior of silane-terminated unsaturated polyurethane before and after surface drying.

[0040] Figure 5 Example 3: Distribution of bromine from the surface to the interior of silane-terminated unsaturated polyurethane after bromine staining treatment of unsaturated bonds before and after surface drying. Detailed Implementation

[0041] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0042] In the following examples, the hardness was tested on different coating surfaces using a QHQ-A push-type pencil hardness tester (700±50g) according to the national standard GB / T 6739-2006. Zhonghua brand pencils of different hardnesses were inserted into the pencil hardness tester and secured with clips. The pencil tips were placed on the coating surface, and the test plate was pushed at least 7mm towards the operator. The scratches were observed. If scratches exceeding 3mm appeared, the pencil hardness was reduced, and the test was repeated until scratches exceeding 3mm no longer appeared. The pencil hardness of the coating was represented by the hardest pencil that did not cause scratches of 3mm or more.

[0043] Adhesion was assessed according to the standard test method for assessing adhesion using tape, as per ASTM D3359-17. The X-cut tape test was conducted using approximately 75mm thick pressure-sensitive tape. The center of the tape was adhered to the interface intersection, air was expelled, and adhesion was allowed for 90±30 seconds. After quickly removing the tape, the cut area was checked for detachment from the substrate. Adhesion was rated as follows: 5A No peeling or removal; 4A Peeling or removal along the cut or its intersection; 3A Removal of serrations up to 1.6mm (1 / 16in.) on both sides of the cut; 2A Serrated cut along most of the cut, up to 3.2mm (1 / 8in.) on both sides; 1A Removal from most of the area beneath the tape; 0A Removal outside the X area.

[0044] Example 1

[0045] Preparation of hydroxysilane: 7.4 g of hydroxyethyl acrylate, 12.5 g of KH590 and 0.2 g of azobisisobutyronitrile (AIBN) were added to a three-necked flask equipped with a magnetic stirrer and a thermometer. The reaction was carried out at 70 °C with stirring for 7 h, and nitrogen gas was introduced throughout the process.

[0046] Preparation of silane-terminated unsaturated polyurethane: 5.000 g hexamethylene diisocyanate, 1.745 g cis-2-buten-1,4-diol, and 0.025 g dibutyltin dilaurate were added to 30 mL N,N-dimethylformamide (DMF) and stirred at 50 °C for 2 h under dry nitrogen. Then, 2 g of the synthesized silane coupling agent was added, and the reaction was carried out at 60 °C for 1 h. The reaction was stopped by cooling to room temperature.

[0047] Preparation of a polyurethane coating with hydrophobic and multiple curing properties: 0.2g of benzoin dimethyl ether was added to the above-prepared silane-terminated unsaturated polyurethane, and the mixture was stirred at 60°C for 30 minutes. The mixture was then poured into a pre-prepared dry glass dish with a diameter of 60mm, irradiated under a UV lamp for 20 minutes, and then placed in an oven at 80°C for 30 minutes to cure and form a film.

[0048] Example 2

[0049] Preparation of hydroxysilane: 7.4 g of hydroxyethyl acrylate, 12.5 g of KH590 and 0.2 g of azobisisobutyronitrile (AIBN) were added to a three-necked flask equipped with a magnetic stirrer and a thermometer. The reaction was carried out at 70 °C with stirring for 7 h, and nitrogen gas was introduced throughout the process.

[0050] Preparation of silane terminated unsaturated polyurethane: 5.000 g of hexamethylene diisocyanate, 1.745 g of cis-2-butene-1,4-diol, 0.025 g of dibutyl tin dilaurate were added to 30 mL of N,N dimethylformamide (DMF) and stirred at 50 °C for 2 h under dry nitrogen, followed by the addition of 2 g of the silane coupling agent synthesized above and reacted at 60 °C for 1 h, and the reaction was stopped by cooling to room temperature.

[0051] Preparation of polyurethane coating with hydrophobic and multi-cure properties: 0.2 g of benzpinacol was added to the silane terminated unsaturated polyurethane prepared above and mixed at 60 °C for 30 min, poured into a previously prepared dry glass dish of 60 mm diameter, irradiated under UV lamp for 15 min, and then placed in an oven at 80 °C for 30 min to form a film. The cured coating was placed in a 60 °C water bath for 1 h.

[0052] Example 3

[0053] Preparation of hydroxyl silane: 7.4 g of hydroxyethyl acrylate, 12.5 g of KH590, and 0.2 g of azobisisobutyronitrile (AIBN) were added to a three-necked flask equipped with magnetic stirring and a thermometer. The reaction was carried out at 70 °C for 7 h under stirring with nitrogen gas being passed throughout the reaction.

[0054] Preparation of silane terminated unsaturated polyurethane: 5.000 g of hexamethylene diisocyanate, 1.745 g of cis-2-butene-1,4-diol, 0.025 g of dibutyl tin dilaurate were added to 30 mL of N,N dimethylformamide (DMF) and stirred at 50 °C for 2 h under dry nitrogen, followed by the addition of 2 g of the silane coupling agent synthesized above and reacted at 60 °C for 1 h, and the reaction was stopped by cooling to room temperature.

[0055] Preparation of polyurethane coating with hydrophobic and multi-cure properties: 0.2 g of benzpinacol was added to the silane terminated unsaturated polyurethane prepared above and mixed at 60 °C for 30 min, poured into a previously prepared dry glass dish of 60 mm diameter, irradiated under UV lamp for 15 min, and then placed in an oven at 80 °C for 30 min to form a film. The cured coating was placed in a 60 °C water bath for 1 h.

[0056] Example 4

[0057] Preparation of hydroxyl silane: 7.4 g of hydroxyethyl acrylate, 12.5 g of KH590, and 0.2 g of azobisisobutyronitrile (AIBN) were added to a three-necked flask equipped with magnetic stirring and a thermometer. The reaction was carried out at 70 °C for 7 h under stirring with nitrogen gas being passed throughout the reaction.

[0058] Preparation of silane terminated unsaturated polyurethane: 5.000 g of hexamethylene diisocyanate, 1.308 g of cis-2-butene-1,4-diol, 0.025 g of dibutyl tin dilaurate were added to 30 mL of N,N dimethylformamide (DMF) and stirred at 50 °C for 2 h under dry nitrogen, followed by addition of 2 g of silane coupling agent synthesized above and reacted at 60 °C for 1 h, cooled to room temperature and the reaction was stopped.

[0059] Preparation of polyurethane coating with hydrophobic and multi-cure properties: 0.2 g of benzpinacol was added to the silane terminated unsaturated polyurethane prepared above and mixed at 60 °C for 30 min, poured into a previously prepared dry glass dish of 60 mm diameter and irradiated under UV lamp for 15 min, followed by curing in an oven at 80 °C for 30 min to form a film.

[0060] Example 5

[0061] Preparation of hydroxyl silane: 3.7 g of allyl alcohol, 12.5 g of KH590 and 0.2 g of azobisisobutyronitrile (AIBN) were added to a three necked flask equipped with magnetic stirring and thermometer. The reaction was carried out at 70 °C for 7 h under stirring and nitrogen flow.

[0062] Preparation of silane terminated unsaturated polyurethane: 5.000 g of isophorone diisocyanate, 1.745 g of cis-2-butene-1,4-diol, 0.025 g of dibutyl tin dilaurate were added to 30 mL of N,N dimethylformamide (DMF) and stirred at 50 °C for 2 h under dry nitrogen, followed by addition of 2 g of silane coupling agent synthesized above and reacted at 60 °C for 1 h, cooled to room temperature and the reaction was stopped.

[0063] Preparation of polyurethane coating with hydrophobic and multi-cure properties: 0.2 g of benzpinacol was added to the silane terminated unsaturated polyurethane prepared above and mixed at 60 °C for 30 min, poured into a previously prepared dry glass dish of 60 mm diameter and irradiated under UV lamp for 15 min, followed by curing in an oven at 80 °C for 30 min to form a film.

[0064] Comparative Example 1

[0065] Preparation of PU prepolymer coating: 5.000 g of hexamethylene diisocyanate, 1.745 g of cis-2-butene-1,4-diol were added to a three-necked flask equipped with a magnetic stirrer and purged with dry nitrogen, 0.025 g of dibutyltin dilaurate was added as a catalyst, 30 mL of DMF was added as a solvent, and the reaction was carried out at 50°C for 2 h to obtain an unsaturated polyurethane having a terminal -NCO group. 0.2 g of benzoin dimethyl ether was added to the above-prepared terminal silane unsaturated polyurethane, mixed and stirred at 60°C for 30 min, poured into a previously prepared dry glass dish with a diameter of 60 mm, irradiated under a UV lamp for 15 min, and then placed in an oven at 80°C for 30 min to form a film.

[0066] The contact angle, adhesion, and hardness of Comparative Example 1 were lower than those of Example 3. From the above results, it can be seen that the silane in Example 3 migrated and aggregated to the surface of the coating after curing. Therefore, the contact angle and surface hardness of Comparative Example 1 were lower than those of Example 3 due to the lack of the silane component. On the other hand, the silane contained in Example 3 forms silanol groups after absorbing moisture in the air and forms a strong chemical bond with the hydroxyl groups on the surface of the adherend. Since Comparative Example 1 does not contain silane, it interacts with the adherend by forming hydrogen bonds or other strong interactions with the urethane on the surface of the adherend. Therefore, the adhesion of Comparative Example 1 is also lower than that of Example 3. Figure 3 It can be seen that Example 3 has a stretching vibration peak of Si-O-C at 1095 cm -1 Figure 4 It can be seen that the silane in Example 3 migrated and aggregated to the surface of the coating after curing. Therefore, the contact angle and surface hardness of Comparative Example 1 were lower than those of Example 3 due to the lack of the silane component. On the other hand, the silane contained in Example 3 forms silanol groups after absorbing moisture in the air and forms a strong chemical bond with the hydroxyl groups on the surface of the adherend. Since Comparative Example 1 does not contain silane, it interacts with the adherend by forming hydrogen bonds or other strong interactions with the urethane on the surface of the adherend. Therefore, the adhesion of Comparative Example 1 is also lower than that of Example 3.

[0067] Comparative Example 2

[0068] Preparation of hydroxyl silane: 7.4 g of hydroxyethyl acrylate, 12.5 g of KH590, and 0.2 g of azobisisobutyronitrile (AIBN) were added to a three-necked flask equipped with a magnetic stirrer and a thermometer. The reaction was carried out at 70°C for 7 h with stirring and nitrogen was purged throughout the process.

[0069] Preparation of terminal silane unsaturated polyurethane: 5.000 g of hexamethylene diisocyanate, 1.745 g of cis-2-butene-1,4-diol, and 0.025 g of dibutyltin dilaurate were added to 30 mL of N,N-dimethylformamide (DMF) and stirred at 50°C for 2 h under dry nitrogen, followed by the addition of 2 g of the above-synthesized silane coupling agent and reaction at 60°C for 1 h, and cooling to room temperature to stop the reaction.

[0070] Preparation of polyurethane coating having hydrophobicity and multiple curing properties: 0.2 g of benzoin dimethyl ether was added to the above-prepared terminal silane unsaturated polyurethane, mixed and stirred at 60°C for 30 min, poured into a previously prepared dry glass dish with a diameter of 60 mm, and directly formed a film without UV curing and thermal curing.​

[0071] The coating of Comparative Example 2 cracked after film formation and exhibited poor performance. The reasons for the poor performance of Comparative Example 2 are mainly the following three points: 1. The coating was not cured by UV light, which caused a dense cross-linked layer to form on the surface of the coating to achieve rapid "surface drying" of the coating, and the solvent evaporation rate did not match the curing rate of the coating. The solvent contained therein caused surface cracks in the coating after rapid evaporation. 2. The coating, which was not cured by UV light and heat, could not migrate and enrich the surface of the silicon element, and the silicon element exhibited a phenomenon of uniform distribution throughout the depth of the coating. Figure 4 )3. Without UV curing and heat curing, the curing can only be completed by limited silane through wet curing, and the coating has low cross-linking degree and small strength. The above three factors all lead to smaller surface hardness and weaker adhesion of Comparative Example 2 than Example 3.

[0072] Comparative Example 3

[0073] Preparation of hydroxyl silane: 7.4 g of hydroxyethyl acrylate, 12.5 g of KH590 and 0.2 g of azobisisobutyronitrile (AIBN) were added to a three-necked flask equipped with magnetic stirring and a thermometer. The reaction was carried out at 70°C for 7h under stirring and nitrogen was passed throughout the process.

[0074] Preparation of silane-terminated unsaturated polyurethane: 5.000 g of hexamethylene diisocyanate, 2.181 g of cis-2-butene-1,4-diol, and 0.025 g of dibutyltin dilaurate were added to 30 mL of N,N-dimethylformamide (DMF) and stirred at 50°C for 2h under dry nitrogen, followed by the addition of 2 g of the above-synthesized silane coupling agent, and reaction at 60°C for 1h, and cooling to room temperature to stop the reaction.

[0075] Preparation of polyurethane coating with hydrophobicity and multiple curing properties: 0.2 g of benzylic dimethyl ether was added to the above-prepared silane-terminated unsaturated polyurethane, mixed and stirred at 60°C for 30 minutes, poured into a previously prepared dry glass dish with a diameter of 60 mm, irradiated under a UV lamp for 15 minutes, and then placed in an oven at 80°C for 30 min to form a film.

[0076] Comparative Example 3 cracked after film formation and exhibited poor performance. Compared with Example 3, Comparative Example 3 has a larger soft segment content. Therefore, during the preparation of silane-terminated unsaturated polyurethane, Comparative Example 3 requires a longer reaction time to complete the reaction. Under the same reaction time, Comparative Example 3 has more small molecular components that do not participate in the reaction or have a lower reaction degree compared with Example 3. Therefore, when the silane-terminated unsaturated polyurethane of Comparative Example 3 forms a coating, due to the large difference in molecular weight of the components and the difference in the consistency and drying rate of each component, cracks and poor adhesion occur.

[0077] The state of the silane-terminated unsaturated polyurethane coating films obtained in the examples and comparative examples is shown in Table 1 below.

[0078] Table 1

[0079]

Claims

1. A polyurethane coating with hydrophobicity and multiple curing properties, characterized in that, Prepared as follows: Mix terminal silane unsaturated polyurethane and benzoin dimethyl ether, stir at 60°C for 30 minutes, pour into a dry glass dish, irradiate under a UV lamp first, and then place in an oven to cure into a film; the mass percentage of benzoin dimethyl ether in the raw materials is 2.2~2.3%; UV irradiation time is 15~20 min; oven curing conditions: 80°C, 30 min; in, Silane-terminated unsaturated polyurethane was prepared by the following method: S1: Preparation of terminal hydroxyl silanes A hydroxyl-containing olefin compound, a mercaptosilane coupling agent, and a catalyst were mixed and reacted under nitrogen protection and at 70°C for 7 hours to obtain a terminal hydroxyl silane. Hydroxyl-containing olefins are selected from: hydroxyethyl acrylate or allyl alcohol; The mercaptosilane coupling agent is γ-mercaptopropyltrimethoxysilane; The catalyst is azobisisobutyronitrile; S2: Preparation of silane-terminated unsaturated polyurethane Aliphatic diisocyanate, unsaturated diol and catalyst were dissolved in a solvent and stirred at 50°C for 2 hours under dry nitrogen to obtain an unsaturated polyurethane prepolymer with -NCO end groups. The terminal hydroxyl silane prepared by S1 was added and the reaction was continued at 60°C for 1 hour. After cooling to room temperature, the silane-terminated unsaturated polyurethane was obtained. The mass ratio of aliphatic diisocyanate, unsaturated diol, catalyst, and terminal hydroxyl silane is 5:1.308~2.181:0.025:2; The fatty diisocyanate is selected from one of the following: hexamethylene diisocyanate and isoflurone diisocyanate; The unsaturated diol is cis-2-buten-1,4-diol; The catalyst is dibutyltin dilaurate.

2. The polyurethane coating with hydrophobicity and multiple curing properties as described in claim 1, characterized in that, In method S1 for preparing silane-terminated unsaturated polyurethane, the mass ratio of hydroxyl-containing olefin compound, mercaptosilane coupling agent, and catalyst is 3.7~7.4:12.5:0.

2.

3. The polyurethane coating with hydrophobicity and multiple curing properties as described in claim 1, characterized in that, In method S2 for preparing silane-terminated unsaturated polyurethane, the solvent is selected from anhydrous acetone or N,N-dimethylformamide.

4. The polyurethane coating with hydrophobicity and multiple curing properties as described in claim 1, characterized in that, The molar ratio of isocyanate groups (-NCO) to hydroxyl groups (-OH) in the reaction raw materials for preparing silane-terminated unsaturated polyurethanes ranges from 1.2 to 2.

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