Water-blocking glue and preparation method and application thereof

Abstract

The invention relates to a water-blocking adhesive and a preparation method and application thereof, and the preparation method of the water-blocking adhesive comprises the following steps: (1) preparing modified polyol: uniformly mixing anhydride, long carbon chain polyol, a catalyst and a solvent, and reacting to obtain a polyol product after the reaction is finished; uniformly mixing the polyol product with castor oil polyol to obtain modified polyol for later use; preparing a polyurethane prepolymer: uniformly mixing diisocyanate, polyether polyol and a catalyst, and reacting to obtain the polyurethane prepolymer for later use; and (2) during use, uniformly mixing the prepared modified polyol with the prepared polyurethane prepolymer, and reacting to obtain the water-blocking adhesive. According to the invention, the modified polyol with a long alkane chain segment is used and matched with the castor oil polyol, so that the structural strength of the water-blocking adhesive is further improved, the water-blocking adhesive has an excellent water-blocking effect, and the problem that the water-blocking structure is damaged in a high-pressure state is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of water-blocking adhesives, and in particular to a water-blocking adhesive and a preparation method and application thereof. Background Art

[0002] Compared with the land environment, the deep sea environment has special environmental problems such as seawater erosion, large temperature difference, and high environmental pressure, so the cables in deep sea equipment have higher requirements. At present, ordinary cables are often used in deep sea equipment, but ordinary cables cannot adapt to the high water pressure environment of the deep sea, and are prone to water leakage. In more serious cases, seawater will enter the cable and corrode the cable, causing the cable to be scrapped or even damaging the deep sea equipment connected to the cable. Therefore, deep sea water blocking glue needs to take into account the use environment of optical fiber cables.

[0003] In the prior art, castor oil modified materials have excellent water-blocking properties and are widely used in the field of water-blocking adhesives. However, due to the relatively weak structural strength of castor oil modified materials, they are easily broken under high pressure, which deteriorates the water-blocking effect. Deep-sea optical fiber materials are accompanied by high pressure under the sea. When the external structure is damaged, such as when being bitten by sharks, the water-blocking effect of castor oil will be greatly reduced.

[0004] Therefore, how to achieve a water-blocking adhesive that has both water-blocking effect and structural strength in deep-sea environments has become a problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the above technical problems, the present invention uses modified polyols with long alkane chain segments in combination with castor oil polyol, so that the structural strength of the water-blocking adhesive is further increased, and has excellent water-blocking effect, thereby solving the problem of damage to the water-blocking structure under high pressure.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a water-blocking adhesive, the method for preparing the water-blocking adhesive comprising the following steps:

[0008] (1) Preparing modified polyols: uniformly mixing an acid anhydride, a long carbon chain polyol, a catalyst and a solvent, and reacting them. After the reaction is completed, a polyol product is obtained; uniformly mixing the polyol product with castor oil polyol to obtain the modified polyol for later use;

[0009] Preparation of polyurethane prepolymer: uniformly mixing diisocyanate, polyether polyol and catalyst, reacting to obtain the polyurethane prepolymer for standby use;

[0010] (2) When in use, the prepared modified polyol is uniformly mixed with the prepared polyurethane prepolymer to react to obtain the water-blocking adhesive.

[0011] The present invention adopts a long alkane chain segment modified polyol, which has the same hydrophobic effect as castor oil, but has higher strength than castor oil structure. At the same time, a small number of unsaturated bonds in the modified polyol obtained by compounding the long alkane chain segment modified polyol with castor oil undergo addition reaction at high temperature to form a cross-linked structure, so that the strength of the water-blocking adhesive structure is further increased, solving the problem that the water-blocking structure is easily damaged under high pressure.

[0012] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0013] Preferably, the anhydride comprises maleic anhydride.

[0014] Preferably, the long carbon chain polyol is a C10-C16 long carbon chain polyol.

[0015] Preferably, the C10-C16 long carbon chain polyol is selected from 1,10-decanediol and / or 1,12-dodecanediol.

[0016] In the present invention, C10-C16 long carbon chain polyols are selected, and long carbon chain polyols have a significant effect of improving the mechanical properties of the material. Because they have a long flexible carbon chain, the material is endowed with higher flexibility and ductility. The long carbon chain can form good compatibility in the polymer matrix, reduce stress concentration points, and thus improve the strength of the material. At the same time, C10-C16 has a good hydrophobic effect, which can further provide a water-blocking effect.

[0017] Preferably, the catalyst comprises a sulfonic acid and / or a sulfonate.

[0018] Preferably, the solvent includes any one of toluene, isobutyl alcohol or isopropyl alcohol, or a combination of at least two of them.

[0019] Preferably, the amount of the solvent added is 25-35wt.% of the sum of the amount of the anhydride added and the amount of the long-chain polyol added, for example, it can be 25wt.%, 27wt.%, 29wt.%, 30wt.%, 32wt.%, 34wt.% or 35wt.%.

[0020] Preferably, the molar ratio of the acid anhydride to the long carbon chain polyol is 1:(1.1-1.7), for example, it can be 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6 or 1:1.7.

[0021] Preferably, the amount of the catalyst added is 0.5-0.7 wt.% of the sum of the amount of the acid anhydride added and the amount of the long-chain polyol added, for example, it can be 0.5 wt.%, 0.55 wt.%, 0.6 wt.%, 0.65 wt.% or 0.7 wt.%.

[0022] Preferably, the reaction temperature in the step of preparing the modified polyol is 80-90°C, for example, 80°C, 82°C, 84°C, 86°C, 88°C or 90°C.

[0023] Preferably, the acid value of the product at the end of the reaction in the step of preparing the modified polyol is <5 mgKOH / g, for example, it may be 1 mgKOH / g, 2 mgKOH / g, 3 mgKOH / g, 4 mgKOH / g or 4.5 mgKOH / g.

[0024] Preferably, the step of preparing the modified polyol further includes a post-treatment step after the reaction is completed.

[0025] Preferably, the post-treatment step comprises a solvent removal process.

[0026] Preferably, the number average molecular weight of the castor oil polyol is 800-2000, for example, 800, 1000, 1200, 1400, 1500, 1700, 1900 or 200.

[0027] Preferably, the number average molecular weight of the castor oil polyol is 1000-1500, for example, 1000, 1200, 1300, 1400 or 1500.

[0028] Preferably, the mass ratio of the castor oil polyol to the polyol product is (1-1.6):(2.4-3), wherein "1-1.6" can be 1, 1.1, 1.2, 1.3, 1.4, 1.5 or 1.6; "2.4-3" can be 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.

[0029] Preferably, the mixing temperature of the castor oil polyol and the polyol is 70-90°C, for example, 70°C, 75°C, 80°C, 85°C or 90°C.

[0030] Preferably, the diisocyanate includes any one of diphenylmethane diisocyanate, toluene diisocyanate or meta-xylylene diisocyanate, or a combination of at least two thereof.

[0031] Preferably, the polyether polyol comprises polytetramethylene ether glycol and / or polytrimethylene ether glycol.

[0032] Preferably, the molar ratio of the isocyanate to the polyether polyol is (1.8-2.2):1, for example, it can be 1.8:1, 1.9:1, 2:1, 2.1:1 or 2.2:1.

[0033] Preferably, the catalyst comprises an amine catalyst and / or an organometallic catalyst.

[0034] Preferably, the added amount of the catalyst is 0.05-0.1 wt.% of the sum of the added amounts of isocyanate and polyether polyol, for example, it may be 0.05 wt.%, 0.06 wt.%, 0.07 wt.%, 0.08 wt.%, 0.09 wt.% or 0.1 wt.%.

[0035] Preferably, the reaction temperature in the step of preparing the polyurethane prepolymer is 60-70°C, for example, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C.

[0036] Preferably, the reaction time in the step of preparing the polyurethane prepolymer is 8-10 h, for example, 8 h, 8.5 h, 9 h, 9.5 h or 10 h.

[0037] Preferably, the mass ratio of the modified polyol to the polyurethane prepolymer in step (2) is (1-2):(3-5.7), wherein "1-2" can be 1, 1.2, 1.4, 1.6, 1.8 or 2; "3-5.7" can be 3, 3.5, 4, 4.5, 5, 5.5 or 5.7.

[0038] Preferably, the reaction temperature in step (2) is 10-35°C, for example, 10°C, 15°C, 20°C, 25°C, 30°C or 35°C.

[0039] In a second aspect, the present invention provides a water-blocking adhesive prepared by the method for preparing the water-blocking adhesive as described in the first aspect.

[0040] In a third aspect, the present invention provides a use of the water-blocking adhesive as described in the second aspect in a deep-sea optical cable.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] (1) The present invention adopts a long alkane chain segment modified polyol, which has the same hydrophobic effect as castor oil, but has higher strength than castor oil structure. At the same time, a small number of unsaturated bonds in the modified polyol obtained by compounding the long alkane chain segment modified polyol with castor oil undergo addition reaction at high temperature to form a cross-linked structure, which further increases the strength of the water-blocking adhesive structure and solves the problem that the water-blocking structure is easily damaged under high pressure.

[0043] (2) The water-blocking adhesive provided by the present invention can be used to solve the water-blocking problem of submarine optical cables. The optical cables are assembled, coated with the water-blocking adhesive prepared by the present invention, and placed in a copper tube. The water-blocking adhesive fits the copper tube and covers the optical cable. When water vapor corrodes the copper tube, causing it to rupture, the water-blocking adhesive has excellent bonding strength and hydrophobic properties, which prevents water vapor from further corroding the cable and causing the cable to be scrapped. DETAILED DESCRIPTION

[0044] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0045] The sources of raw materials used in the following examples and comparative examples are as follows:

[0046] 1. Maleic anhydride, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0047] 2. 1,10-Decanediol, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0048] 3. 1,12-Dodecanediol, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0049] 4. 1,16-Dodecanediol, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0050] 5. 1,6-Hexanediol was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0051] 6. 1,20-Eicosanediol, purchased from Shanghai BiDe Pharmaceutical Technology Co., Ltd.;

[0052] 7. p-Toluenesulfonic acid, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0053] 8. Dodecylbenzenesulfonic acid, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0054] 9. Castor oil polyol, brand D1000, purchased from Vantrus;

[0055] 10. Castor oil polyol, brand D2000, purchased from Vantrus;

[0056] 11. Castor oil polyol, brand D3000, purchased from Vantrus;

[0057] 12. Diphenylmethane diisocyanate, purchased from Wanhua Chemical;

[0058] 13. Toluene diisocyanate, purchased from Wanhua Chemical;

[0059] 14. m-Xylylenedimethyl isocyanate, purchased from Mitsui Chemicals, Japan;

[0060] 15. Polytetramethylene glycol, PTMEG1000, purchased from Hyosung, Korea;

[0061] 16. Polytrimethylene ether glycol, H1000, purchased from SK, South Korea;

[0062] 17. Dibutyltin dilaurate, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0063] 18. Bismuth isooctanoate, BCAT, purchased from Guangzhou Yourun Chemical;

[0064] 19. N,N-Dimethylbenzylamine was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0065] Example 1

[0066] A method for preparing a water-blocking adhesive, the method comprising the following steps:

[0067] (1) Preparation of modified polyol: Maleic anhydride and 1,10-decanediol in a molar ratio of 1:1.1, p-toluenesulfonic acid (the amount of which added is 0.5 wt.% of the sum of the amounts of maleic anhydride and 1,10-decanediol added) and toluene (the amount of which added is 35 wt.% of the sum of the amounts of maleic anhydride and 1,10-decanediol added) are uniformly mixed, reacted at 70° C., and the reaction is terminated after the acid value of the reaction product is less than 5 mgKOH / g, and the solvent is removed by reduced pressure distillation to obtain a polyol product;

[0068] Mix castor oil (D1000) polyol and polyol product at a mass ratio of 1:2 at 70° C. to obtain the modified polyol, and seal the package for later use;

[0069] Preparation of polyurethane prepolymer: uniformly mixing diphenylmethane diisocyanate and polytetramethylene glycol in a mass ratio of 1.8:1 with dibutyltin dilaurate (the addition amount thereof is 0.05wt.% of the sum of the addition amounts of diphenylmethane diisocyanate and polytetramethylene glycol), reacting at 60° C. for 10 hours to obtain the polyurethane prepolymer, which is then packed and sealed for standby use;

[0070] (2) When in use, the prepared modified polyol and the prepared polyurethane prepolymer are mixed uniformly at a mass ratio of 1:3 at 20° C. to obtain the water-blocking adhesive.

[0071] Example 2

[0072] A method for preparing a water-blocking adhesive, the method comprising the following steps:

[0073] (1) Preparation of modified polyol: Maleic anhydride and 1,12-dodecanediol in a molar ratio of 1:1.4, dodecylbenzenesulfonic acid (the amount of which added is 0.6 wt.% of the sum of the amounts of maleic anhydride and 1,12-dodecanediol added) and isopropanol (the amount of which added is 25 wt.% of the sum of the amounts of maleic anhydride and 1,12-dodecanediol added) are uniformly mixed, and reacted at 85° C. until the acid value of the reaction product is less than 5 mgKOH / g, and the reaction is terminated, and the solvent is removed by reduced pressure distillation to obtain a polyol product;

[0074] Mix castor oil (D2000) polyol and polyol product at a mass ratio of 1:2.5 at 80° C. to obtain the modified polyol, and seal the package for later use;

[0075] Preparation of polyurethane prepolymer: uniformly mixing toluene diisocyanate and polytrimethylene ether glycol in a mass ratio of 2:1 with bismuth isooctanoate (the addition amount of which is 0.08wt.% of the sum of the addition amounts of toluene diisocyanate and polytrimethylene ether glycol), reacting at 65° C. for 9 hours to obtain the polyurethane prepolymer, which is then packed and sealed for standby use;

[0076] (2) When in use, the prepared modified polyol and the prepared polyurethane prepolymer are mixed uniformly at a mass ratio of 1:4 at 25° C. to obtain the water-blocking adhesive.

[0077] Example 3

[0078] A method for preparing a water-blocking adhesive, the method comprising the following steps:

[0079] (1) Preparation of modified polyol: Maleic anhydride and 1,16-hexadecanediol in a molar ratio of 1:1.7 are uniformly mixed with p-toluenesulfonic acid (the amount of which is 0.7 wt.% of the sum of the amounts of maleic anhydride and 1,16-hexadecanediol) and isobutyl alcohol (the amount of which is 35 wt.% of the sum of the amounts of maleic anhydride and 1,16-hexadecanediol) and reacted at 90° C. until the acid value of the reaction product is less than 5 mgKOH / g, and the reaction is terminated. The solvent is removed by distillation under reduced pressure to obtain a polyol product;

[0080] Mix castor oil (D3000) polyol and polyol product at a mass ratio of 1:3 at 70° C. to obtain the modified polyol, and seal the package for later use;

[0081] Preparation of polyurethane prepolymer: uniformly mixing m-xylylene diisocyanate and polytetramethylene glycol in a mass ratio of 2.2:1 with N,N-dimethylbenzylamine (the addition amount of which is 0.1wt.% of the sum of the addition amounts of m-xylylene diisocyanate and polytetramethylene glycol), reacting at 70° C. for 8 hours to obtain the polyurethane prepolymer, which is then packed and sealed for standby use;

[0082] (2) The prepared modified polyol and the prepared polyurethane prepolymer were uniformly mixed at a mass ratio of 1:5.7 at 30° C. to obtain the water-blocking adhesive.

[0083] Example 4

[0084] A method for preparing a water-blocking adhesive, which is different from that of Example 1 in that the molar ratio of maleic anhydride to 1,10-decanediol in step (1) is 1:1.

[0085] Example 5

[0086] A method for preparing a water-blocking adhesive, which is different from that of Example 1 in that the molar ratio of maleic anhydride to 1,10-decanediol in step (1) is 1:2.

[0087] Example 6

[0088] A method for preparing a water-blocking adhesive, which is different from that of Example 1 in that: in step (1), the mass ratio of castor oil polyol to polyol product is 1:1.

[0089] Example 7

[0090] A method for preparing a water-blocking adhesive, which is different from that of Example 1 in that: in step (1), the mass ratio of castor oil polyol to polyol product is 1:4.

[0091] Example 8

[0092] A method for preparing a water-blocking adhesive, which is different from that of Example 1 in that: the 1,10-decanediol in step (1) is replaced by 1,6-hexanediol, and the molar ratio of maleic anhydride to 1,6-hexanediol is 1:1.1.

[0093] Example 9

[0094] A method for preparing a water-blocking adhesive, which is different from that of Example 1 in that: the 1,10-decanediol in step (1) is replaced by 1,20-eicosandiol, and the molar ratio of maleic anhydride to 1,20-eicosandiol is 1:1.1.

[0095] Comparative Example 1

[0096] A method for preparing a water-blocking adhesive, the method comprising the following steps:

[0097] (1) Preparation of modified polyols: Maleic anhydride and 1,10-decanediol in a molar ratio of 1:1.1 are uniformly mixed with p-toluenesulfonic acid (the amount of which is 0.5 wt.% of the sum of the amounts of maleic anhydride and 1,10-decanediol) and toluene (the amount of which is 35 wt.% of the sum of the amounts of maleic anhydride and 1,10-decanediol), and reacted at 70° C. until the acid value of the reaction product is less than 5 mgKOH / g, and the reaction is terminated. The solvent is removed by distillation under reduced pressure to obtain a polyol product, which is packaged and sealed for standby use;

[0098] Preparation of polyurethane prepolymer: uniformly mixing diphenylmethane diisocyanate and polytetramethylene glycol in a mass ratio of 1.8:1 with dibutyltin dilaurate (the addition amount is 0.05wt.% of the sum of the mass of diphenylmethane diisocyanate and polytetramethylene glycol), reacting at 60° C. for 10 hours to obtain the polyurethane prepolymer, which is then packed and sealed for standby use;

[0099] (2) The prepared polyol product and the prepared polyurethane prepolymer were uniformly mixed at a mass ratio of 1:3 at 20° C. to obtain the water-blocking adhesive.

[0100] Comparative Example 2

[0101] A method for preparing a water-blocking adhesive, the method comprising the following steps:

[0102] (1) preparing a polyurethane prepolymer: uniformly mixing diphenylmethane diisocyanate and polytetramethylene glycol in a mass ratio of 1.8:1 with dibutyltin dilaurate (the amount of which is 0.05 wt.% of the sum of the mass of diphenylmethane diisocyanate and polytetramethylene glycol), reacting at 60° C. for 10 h to obtain the polyurethane prepolymer, which is then packaged and sealed for later use;

[0103] (2) Castor oil and the prepared polyurethane prepolymer were mixed uniformly at a mass ratio of 1:3 at 20° C. to obtain the water-blocking adhesive.

[0104] Test Method

[0105] Adhesion strength test (copper to copper):

[0106] The glue is mixed according to the ratio in the above embodiment (comparative example) and then coated on a copper sheet (70×70×0.1mm). The coating area is half a sheet, that is, 30×70mm of glue is coated on any side from the edge, and the thickness of the glue layer is about 20μm. Then take another 70×70×0.1mm copper sheet and start covering the center of the previous copper sheet. The overlapping area of ​​the two copper sheets is 35×70mm, and the overlapping area needs to cover the entire glue area. Then use a hot press to perform hot pressing. The hot pressing pressure is set at 8MPa, the hot pressing temperature is 120℃, the time is 300s, and then cooled to 25℃.

[0107] A universal tensile machine was used to test the bonding strength. A 200N sensor was used to fix the hot-pressed copper laminated sheet with clamps at both ends. The clamping lengths of the clamps at both ends were 20mm, and the middle clamping distance was 55mm. The maximum peeling force (N) when pulled apart was tested.

[0108] Water contact angle: The glue was mixed according to the ratios in the above Examples 1-9 and Comparative Examples 1-2 and then coated on a smooth and flat glass sheet with a coating thickness of 40 μm. The mixture was then transferred to a 120° C. oven and baked for 25 min. The mixture was taken out and cooled. The water contact angle of the coated surface was tested using a water contact angle meter.

[0109] Test Results

[0110] Table 1

[0111] Peel force(N) Water contact angle° Example 1 167 95.3 Example 2 159 95.1 Example 3 162 94.4 Example 4 147 94.8 Example 5 148 93.7 Example 6 146 92.4 Example 7 144 92.1 Example 8 142 92.1 Example 9 143 91.4 Comparative Example 1 103 78.5 Comparative Example 2 48 85.3

[0112] The test results show that:

[0113] (1) It can be seen from Examples 1 to 9 that the water-blocking adhesive prepared by compounding the long alkane chain modified polyol with castor oil has strong bonding strength, a peel force greater than 140N, excellent waterproof effect, and a water contact angle greater than 90°, and can be used to achieve a water-blocking effect in special environments.

[0114] (2) It can be seen from Example 1 and Comparative Example 1 that when the water-blocking adhesive does not contain castor oil, the water-blocking effect decreases by about 18%, and the bonding strength decreases by about 38%, which cannot solve the problem of easy damage to the water-blocking structure under high pressure and effective water blocking.

[0115] (3) It can be seen from Example 1 and Comparative Example 2 that the conventional castor oil-polyurethane prepolymer glue has a worse bonding strength and cannot meet actual production needs.

[0116] The applicant declares that the above is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a water-blocking adhesive, characterized in that: The preparation method of the water-blocking adhesive comprises the following steps: (1) Preparing modified polyols: uniformly mixing an acid anhydride, a long carbon chain polyol, a catalyst and a solvent, and reacting them. After the reaction is completed, a polyol product is obtained; uniformly mixing the polyol product with castor oil polyol to obtain the modified polyol for later use; Preparation of polyurethane prepolymer: uniformly mixing diisocyanate, polyether polyol and catalyst, reacting to obtain the polyurethane prepolymer for standby use; (2) When in use, the prepared modified polyol is uniformly mixed with the prepared polyurethane prepolymer to react to obtain the water-blocking adhesive.

2. The method for preparing the water-blocking adhesive according to claim 1, characterized in that: The acid anhydride includes maleic anhydride; Preferably, the long carbon chain polyol is a C10-C16 long carbon chain polyol; Preferably, the catalyst comprises a sulfonic acid and / or a sulfonate; Preferably, the solvent comprises any one of toluene, isobutyl alcohol or isopropyl alcohol, or a combination of at least two thereof; Preferably, the amount of the solvent added is 25-35 wt.% of the sum of the amount of the acid anhydride added and the amount of the long-chain polyol added; Preferably, the molar ratio of the acid anhydride to the long carbon chain polyol is 1:(1.1-1.7); Preferably, the amount of the catalyst added is 0.5-0.7 wt.% of the sum of the amount of the acid anhydride added and the amount of the long-chain polyol added; Preferably, the reaction temperature in the step of preparing the modified polyol is 80-90°C; Preferably, in the step of preparing the modified polyol, the acid value of the product at the end of the reaction is ≤5 mgKOH / g; Preferably, the step of preparing the modified polyol further comprises a post-treatment step after the reaction is completed; Preferably, the post-treatment step comprises a solvent removal process.

3. The method for preparing the water-blocking adhesive according to claim 1 or 2, characterized in that: The number average molecular weight of the castor oil polyol is 800-2000.

4. The method for preparing the water-blocking adhesive according to any one of claims 1 to 3, characterized in that: The number average molecular weight of the castor oil polyol is 1000-1500.

5. The method for preparing the water-blocking adhesive according to any one of claims 1 to 4, characterized in that: The mass ratio of the castor oil polyol to the polyol product is (1-1.6):(2.4-3); Preferably, the mixing temperature of the castor oil polyol and the polyol is 70-90°C.

6. The method for preparing the water-blocking adhesive according to any one of claims 1 to 5, characterized in that: The diisocyanate includes any one of diphenylmethane diisocyanate, toluene diisocyanate or meta-xylylene diisocyanate or a combination of at least two thereof; Preferably, the polyether polyol comprises polytetramethylene ether glycol and / or polytrimethylene ether glycol; Preferably, the molar ratio of the isocyanate to the polyether polyol is (1.8-2.2):1; Preferably, the catalyst comprises an amine catalyst and / or an organometallic catalyst; Preferably, the added amount of the catalyst is 0.05-0.1 wt.% of the sum of the added amounts of the isocyanate and the polyether polyol.

7. The method for preparing the water-blocking adhesive according to any one of claims 1 to 6, characterized in that: The reaction temperature in the step of preparing the polyurethane prepolymer is 60-70°C; Preferably, the reaction time in the step of preparing the polyurethane prepolymer is 8-10 hours.

8. The method for preparing the water-blocking adhesive according to any one of claims 1 to 7, characterized in that: The mass ratio of the modified polyol to the polyurethane prepolymer in step (2) is (1-2):(3-5.7); Preferably, the reaction temperature in step (2) is 10-35°C.

9. A water-blocking adhesive prepared by the method for preparing the water-blocking adhesive according to any one of claims 1 to 8.

10. Use of the water-blocking adhesive as claimed in claim 9 in deep-sea optical cables.