An ultra-soft bio-based solvent-free blocked polyurethane resin and a preparation method thereof

Abstract

This invention relates to the field of closed-cell polyurethane synthesis technology, and in particular to an ultra-soft, bio-based, solvent-free closed-cell polyurethane resin and its preparation method. An ultra-soft, bio-based, solvent-free closed-cell polyurethane resin comprises a closed-cell polyurethane prepolymer and an amino-terminated polysiloxane with a molecular weight of 800-2000; the mass ratio of the amino-terminated polysiloxane with a molecular weight of 800-2000 to the closed-cell polyurethane prepolymer is (6-25):100; the closed-cell polyurethane prepolymer is made from the following raw materials in parts by weight: diisocyanate, bio-based polyol, blocking agent, catalyst, defoamer, leveling agent, and anti-aging agent. This invention uses diamino-modified polysiloxane for post-chain extension, resulting in a film layer with a significantly lower modulus than films prepared with existing diamine curing agents, giving it a full, soft feel and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of closed polyurethane synthesis technology, and in particular to an ultra-soft, bio-based, solvent-free closed polyurethane resin and its preparation method. Background Technology

[0002] With increasing environmental awareness, solvent-free blocked polyurethane resins have become a hot topic in polyurethane research and development. Blocked isocyanates are compounds with one or more terminal isocyanate groups blocked by a blocking agent that cannot be deblocked at low temperatures (such as methanol, ethanol, caprolactam, methylacetamide, succinimide, acetanilide, glyceryl carbonate, phenol, acetylacetone, etc.). Blocked isocyanates are chemically stable at room temperature, but at higher temperatures, they deblock into free isocyanate groups and the blocking agent, regaining their reactivity. When mixed with amine curing agents, they can crosslink at higher temperatures to form a cured product.

[0003] Existing blocked polyurethane resins, such as the solvent-free blocked polyurethane resin composition disclosed in Chinese Patent CN112625213B, are prepared by comprising 100 parts of blocked polyurethane prepolymer, 4-13 parts of 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM), and 0.1-10 parts of polycat SA8. The raw materials for preparing the blocked polyurethane prepolymer include the following components by mass percentage: 63.2-80% polyol, 0-5% chain extender, 0-5% crosslinking agent, 5-22% isocyanate, 0-1% synergist, 1-15% blocking agent, and 0.2-1% leveling agent. The polyol includes polyester polyols and / or polyether polyols with a molecular weight of 250-10000.

[0004] Existing blocked solvent-free polyurethane technologies typically employ a production process involving prepolymerization of polyether or polyester diols with isocyanates, followed by blocking with ketoximes or pyrazole compounds. Before application, the polyurethane is mixed with MACM and subjected to chain extension at high temperatures to form a film. However, the resulting film lacks sufficient flexibility, significantly limiting its applications. Furthermore, existing blocked solvent-free polyurethanes use petroleum-based polyols as raw materials, and their environmental performance needs improvement. Therefore, the inventors provide an ultra-soft, bio-based, solvent-free blocked polyurethane resin and its preparation method. Summary of the Invention

[0005] To address the technical issues of insufficient softness and inadequate environmental performance of existing closed-type polyurethane resin curing films, this invention develops an ultra-soft, bio-based solvent-free closed-type polyurethane resin using bio-based polyols as raw materials and its preparation method.

[0006] The present invention provides an ultra-soft, bio-based, solvent-free, blocked polyurethane resin, which is achieved through the following technical solution: An ultra-soft, bio-based, solvent-free, blocked polyurethane resin comprises a blocked polyurethane prepolymer and an amino-terminated polysiloxane with a molecular weight of 800-2000; the mass ratio of the amino-terminated polysiloxane with a molecular weight of 800-2000 to the blocked polyurethane prepolymer is (6-25):100.

[0007] This invention uses diamine-modified polysiloxane for post-chain extension, and the modulus of the prepared film is significantly lower than that of the film prepared by existing diamine curing agents, giving it a full and soft feel and environmental friendliness. In addition, diamine-modified polysiloxane can introduce siloxy groups into the molecular chain, which can improve the overall wear resistance, slip and non-stick properties.

[0008] Preferably, the closed polyurethane prepolymer is made from the following raw materials in parts by weight: 10-20 parts of diisocyanate, 80-90 parts of bio-based polyol, 1.5-3.0 parts of blocker, 0.05-0.20 parts of catalyst, 0.05-0.20 parts of defoamer, 0.2-0.5 parts of leveling agent, and 0.05-0.20 parts of anti-aging agent.

[0009] Preferably, the bio-based polyols include castor oil polyols and PO3G polyols, wherein the hydroxyl value of the castor oil polyols is 80-300 mgKOH / g; and the hydroxyl value of the PO3G polyols is 35-120 mgKOH / g.

[0010] The closed polyurethane prepolymer of this invention uses bio-based polyol + diisocyanate prepolymer, which endows the ultra-soft bio-based solvent-free closed polyurethane resin with excellent green and environmentally friendly properties.

[0011] Preferably, the diisocyanate is at least one of TDI-80, TDI-100, TDI-65, MDI-100, MDI-50, carbodiimide-modified MDI-100HL, and carbodiimide-modified MDI-100LL.

[0012] Preferably, the blocking agent is at least one of acetanilide, methyl ethyl ketone oxime, 3,5-dimethylpyrazole, 1,2,4-triazole, acetylacetone, butanone oxime, and acetone oxime.

[0013] By adopting the above technical solution, the unsealing temperature is controlled at 100-140℃, which facilitates subsequent unsealing processing.

[0014] Preferably, the catalyst is an organic bismuth and / or an organic zinc; the organic bismuth is at least one of bismuth isooctanoate BiCAT 8118, BiCAT 8108, and BiCAT 8124; and the organic zinc is at least one of zinc isooctanoate 825-1, zinc isooctanoate 825-4, zinc isooctanoate 825-12, and zinc isooctanoate BiCAT ZM.

[0015] Preferably, the defoamer is an organosilicon defoamer, and the organosilicon defoamer is at least one of BYK-060N, BYK-066N, and BYK-A530; Preferably, the leveling agent is any one of BYK-UV3510, BYK-UV3500, TEGO Flow300, TEGO Rad2200N, and TEGO Rad2100.

[0016] By adopting the above technical solutions, the leveling properties, processability, and film-forming properties of the finished product can be improved.

[0017] Preferably, the anti-aging agent includes an antioxidant and an anti-ultraviolet agent, wherein the antioxidant is at least one selected from antioxidant BHT, antioxidant 245, antioxidant 1010, antioxidant 1035, antioxidant 1076, antioxidant 1098, antioxidant 3114, and antioxidant 168; and the anti-ultraviolet agent is at least one selected from UV-292, UV-622, UV-770, UV-944, UV-5050, UV-5060, UV-5151, UV-531, and UV-327.

[0018] By adopting the above technical solutions, the anti-aging and weather resistance of the formed solidified material can be improved.

[0019] The present invention provides a method for preparing an ultra-soft, bio-based, solvent-free, blocked polyurethane resin, which is achieved through the following technical solution: A method for preparing an ultra-soft, bio-based, solvent-free, blocked polyurethane resin includes the following steps: Step 1: Vacuum dehydration treatment of bio-based polyols; Step 2: Under nitrogen protection, the vacuum-dehydrated bio-based polyol and anti-aging agent are mixed evenly, the temperature is adjusted to 50-60℃, diisocyanate is added, and the reaction is carried out at 80-85℃ for 100-135 min. Then, a catalyst is added, and the reaction is carried out at 80-95℃ for 50-75 min. The sample is taken for testing, and the -NCO% content of the material in the system reaches the theoretical value, which is 0.5-1.0%. A blocking agent is added, and the reaction is carried out at 80-90℃ for 50-75 min. The sample is taken for testing, and the -NCO% content of the material is 0. Then, a defoamer and a leveling agent are added, and the mixture is stirred for 15-45 min to obtain a bio-based solvent-free blocked polyurethane prepolymer. Step 3: Mix the bio-based solvent-free blocked polyurethane prepolymer and amino-terminated polysiloxane at a mass ratio of (10-25):100 to obtain the ultra-soft bio-based solvent-free blocked polyurethane resin.

[0020] The preparation method of the ultra-soft bio-based solvent-free blocked polyurethane resin provided in this invention is mature, simple to operate, and easy to mass-produce.

[0021] In summary, the present invention has the following advantages: 1. Compared with traditional solvent-based resin processes, the preparation method in this invention does not have any solvent pollution problems, is clean and environmentally friendly, and conforms to the trend of green production.

[0022] 2. The automotive leather prepared using this invention has a full and soft feel, and also has good weather resistance, folding resistance, abrasion resistance, and processing performance, enriching the types of automotive leather and expanding the application range of closed polyurethane.

[0023] 3. This invention uses bio-based polyols instead of petroleum-based polyols, giving the closed polyurethane prepolymer excellent environmentally friendly production performance, which is in line with the trend of green production. Detailed Implementation

[0024] To further understand the inventiveness and technical advancements of this invention, the preferred embodiments of this invention will be discussed in detail below with reference to examples and comparative examples.

[0025] Example: An ultra-soft bio-based solvent-free blocked polyurethane resin comprises a blocked polyurethane prepolymer and an amino-terminated polysiloxane with a molecular weight of 800-2000, wherein the mass ratio of the amino-terminated polysiloxane with a molecular weight of 800-2000 to the blocked polyurethane prepolymer is (6-25):100.

[0026] The closed-cell polyurethane prepolymer is made from the following raw materials in parts by weight: 10-20 parts diisocyanate, 80-90 parts bio-based polyol, 1.5-3.0 parts blocker, 0.05-0.20 parts catalyst, 0.05-0.20 parts defoamer, 0.2-0.5 parts leveling agent, and 0.05-0.20 parts anti-aging agent.

[0027] Bio-based polyols include castor oil polyols and PO3G polyols. The hydroxyl value of castor oil polyols is 80-300 mgKOH / g; the hydroxyl value of PO3G polyols is 35-120 mgKOH / g. The molar ratio of castor oil polyols to PO3G polyols is (4-6):10.

[0028] The diisocyanate is at least one of TDI-80, TDI-100, TDI-65, MDI-100, MDI-50, carbodiimide-modified MDI-100HL, and carbodiimide-modified MDI-100LL.

[0029] The blocking agent is at least one of acetanilide, methyl ethyl ketone oxime, 3,5-dimethylpyrazole, 1,2,4-triazole, and acetylacetone.

[0030] The catalyst is an organobismuth and / or an organozinc.

[0031] The organic bismuth is at least one of bismuth isooctanoate BiCAT 8118, BiCAT 8108, and BiCAT 8124.

[0032] The organic zinc is at least one of zinc isooctanoate 825-1, zinc isooctanoate 825-4, zinc isooctanoate 825-12, and zinc isooctanoate BiCAT ZM.

[0033] The defoamer is a silicone-based defoamer, and the silicone-based defoamer is at least one of BYK-060N, BYK-066N, and BYK-A530.

[0034] The leveling agent is any one of BYK-UV3510, BYK-UV3500, TEGO Flow300, TEGO Rad2200N, and TEGO Rad2100.

[0035] Anti-aging agents include antioxidants and UV protectants. The antioxidant is at least one of the following: antioxidant BHT, antioxidant 245, antioxidant 1010, antioxidant 1035, antioxidant 1076, antioxidant 1098, antioxidant 3114, and antioxidant 168. The UV protectant is at least one of the following: UV-292, UV-622, UV-770, UV-944, UV-5050, UV-5060, UV-5151, UV-531, and UV-327.

[0036] A method for preparing an ultra-soft, bio-based, solvent-free, blocked polyurethane resin includes the following steps: Step 1: Vacuum dehydration treatment of bio-based polyols; Step 2: Under nitrogen protection, the vacuum-dehydrated bio-based polyol and anti-aging agent are mixed evenly. The temperature is adjusted to 50-60℃, diisocyanate is added, and the reaction is carried out at 80-85℃ for 100-135 minutes. Then, a catalyst is added, and the reaction is carried out at 80-95℃ for 50-75 minutes. The sample is taken for testing. The -NCO% content of the material in the system reaches the theoretical value, which is 0.5-1.0%. A blocking agent is added, and the reaction is carried out at 80-90℃ for 50-75 minutes. The sample is taken for testing. The -NCO% content of the material is 0. Then, a defoamer and a leveling agent are added, and the mixture is stirred for 15-45 minutes to obtain a bio-based solvent-free blocked polyurethane prepolymer. Step 3: Mix the bio-based solvent-free blocked polyurethane prepolymer and amino-terminated polysiloxane at a mass ratio of (10-25):100 to obtain the ultra-soft bio-based solvent-free blocked polyurethane resin.

[0037] Example 1: An ultra-soft bio-based solvent-free blocked polyurethane resin is provided by Suzhou Qitian New Materials Co., Ltd., consisting of 100 parts by weight of bio-based blocked polyurethane prepolymer and 12 parts by weight of diamino-terminated polysiloxane Cheersil 8110 with a molecular weight of 1000 and a functionality of 2.

[0038] The bio-based blocked polyurethane prepolymer was prepared from 15 parts by weight of castor oil polyol (hydroxyl value 225 mgKOH / g, functionality 3, Shanghai Shuyu Chemical Co., Ltd. SY-790), 69 parts by weight of PO3G polyol (hydroxyl value 56.1 mgKOH / g, functionality 2, SK Chemicals H2000, South Korea), 13.3 parts by weight of TDI-80 (Bluestar Chemical Co., Ltd.), 1.8 parts by weight of methyl ethyl ketone oxime (Jinan Huifengda Chemical Co., Ltd.), 0.1 parts by weight of organic bismuth catalyst BiCAT 8124 (Leading Chemicals, USA), 0.1 parts by weight of antioxidant 1010 (Aladdin), 0.01 parts by weight of antioxidant 168 (Aladdin), 0.05 parts by weight of UV-531 (Aladdin), 0.1 parts by weight of defoamer BYK-A530 (BYK, Germany), and 0.4 parts by weight of leveling agent BYK-UV3500 (BYK, Germany).

[0039] A method for preparing an ultra-soft, bio-based, solvent-free, blocked polyurethane resin includes the following steps: Step 1: 15 parts by weight of castor oil polyol (hydroxyl value 225 mgKOH / g, functionality 3) and 69 parts by weight of PO3G polyol (hydroxyl value 56.1 mgKOH / g) were placed under vacuum at 120°C for 2 hours. Step 2: Purge with nitrogen to restore room temperature, then adjust the temperature to 55℃. Under nitrogen protection, add 0.09 parts by weight of antioxidant 1010 and 0.01 parts by weight of antioxidant 168, and stir at 300 rpm for 5 minutes. After mixing thoroughly, add 13.3 parts by weight of TDI-80, adjust the temperature to 80℃, and maintain a constant temperature of 80℃ for 120 minutes. Then add 0.1 parts by weight of organic bismuth catalyst BiCAT8124, and continue to react at a constant temperature of 80℃ for 60 minutes. Sampling and testing showed that the -NCO% content of the material in the system reached the theoretical value (1.0%). 1.8 parts of methyl ethyl ketone oxime were added, and the temperature was adjusted to 90℃ and reacted for 60 min. Sampling and testing showed that the -NCO% content of the material was 0, that is, there was no NCO characteristic peak in the infrared test. Then, 0.1 parts by weight of defoamer BYK-A530 and 0.4 parts by weight of leveling agent BYK-UV3500 were added, and the mixture was stirred at 300 rpm for 30 min to obtain a bio-based solvent-free blocked polyurethane prepolymer. Step 3: Mix the bio-based solvent-free blocked polyurethane prepolymer and the diamino-terminated polysiloxane Cheersil 8110 at a mass ratio of 100:12 to obtain an ultra-soft bio-based solvent-free blocked polyurethane resin mixture, which is ready for use.

[0040] The method for preparing a film using ultra-soft, bio-based, solvent-free, blocked polyurethane resin is as follows: The above resin mixture is coated onto release paper at a coating amount of 25 g / m². 2 Then place it at 110℃ for 2 minutes to fully defoam and self-level, then cure at 130℃ for 2 minutes, then cure at 150℃ for 3 minutes, cool to room temperature, and peel off to obtain the film.

[0041] The method for leather making using ultra-soft, bio-based, solvent-free, blocked polyurethane resin is as follows: The above resin mixture is scraped onto release paper that has already been coated with a top layer of resin, with a scraping amount of 25 g / m². 2 Then, it is placed at 120℃ for about 1 minute to mature. When it is semi-dry, it is attached to the suede base. Finally, it is placed at 130℃ for 2 minutes to cure, and then at 150℃ for 3 minutes to cure. After cooling to room temperature, it can be removed and peeled off to obtain synthetic leather.

[0042] The difference between Example 2 and Example 1 is that the ultra-soft bio-based solvent-free blocked polyurethane resin is provided by Suzhou Qitian New Materials Co., Ltd., consisting of 100 parts by weight of blocked polyurethane prepolymer and 24 parts by weight of diamino-terminated polysiloxane Cheersil 8120 (molecular weight of 2000, functionality of 2).

[0043] The difference between Example 3 and Example 1 is that the ultra-soft bio-based solvent-free blocked polyurethane resin is composed of 100 parts by weight of blocked polyurethane prepolymer, 6 parts by weight of diamino-terminated polysiloxane Cheersil 8110 with a molecular weight of 1000, and 12 parts by weight of diamino-terminated polysiloxane Cheersil 8120 with a molecular weight of 1000.

[0044] The difference between Example 4 and Example 1 is that the ultra-soft bio-based solvent-free blocked polyurethane resin is composed of 100 parts by weight of blocked polyurethane prepolymer and 14.5 parts by weight of self-made amino-terminated polysiloxane.

[0045] The preparation method of diamino-terminated polysiloxane is as follows: 10g (0.01mol) of linear vinyl silicone oil IOTA-273 (molecular weight 1000, vinyl content 5.4%, Anhui Aiyota Silicone Oil Co., Ltd.), 1.62g (0.021mol) of β-mercaptoethylamine (Maclean, CAS: 60-23-1, purity 95%), 0.16g of 2,4-diethylthioxanthone DETX (Aladdin, CAS: 82799-44-8) and 90g of methyl ethyl ketone were magnetically stirred at 300rpm for 15min. The mixture was then ultrasonically dispersed under a UV LED lamp with ultrasonic parameters of 40kHz / 650W, UV wavelength of 365nm, and UV intensity of 80μW / cm². The mixture was reacted at room temperature for 5min. Subsequently, methyl ethyl ketone was removed by vacuum distillation. After dehydration treatment with dehydrating agent-4A zeolite powder, the mixture was filtered to obtain amino-terminated polysiloxane.

[0046] The difference between Example 5 and Example 1 is that the ultra-soft bio-based solvent-free blocked polyurethane resin is composed of 100 parts by weight of bio-based blocked polyurethane prepolymer and 6 parts by weight of diamino-terminated polysiloxane Cheersil 8110 with a molecular weight of 1000.

[0047] The bio-based blocked polyurethane prepolymer was prepared from 15 parts by weight of castor oil polyol (hydroxyl value 225 mgKOH / g, functionality 3, Shanghai Shuyu Chemical Co., Ltd. SY-790), 70.8 parts by weight of PO3G polyol (hydroxyl value 56.1 mgKOH / g, functionality 2, SK Chemicals H2000, South Korea), 12.4 parts by weight of TDI-80 (Bluestar Chemical Co., Ltd.), 0.9 parts by weight of methyl ethyl ketone oxime (Jinan Huifengda Chemical Co., Ltd.), 0.1 parts by weight of organic bismuth catalyst BiCAT 8124 (Leading Chemicals, USA), 0.1 parts by weight of antioxidant 1010 (Aladdin), 0.01 parts by weight of antioxidant 168 (Aladdin), 0.05 parts by weight of UV-531 (Aladdin), 0.1 parts by weight of defoamer BYK-A530 (BYK, Germany), and 0.4 parts by weight of leveling agent BYK-UV3500 (BYK, Germany).

[0048] A method for preparing an ultra-soft, bio-based, solvent-free, blocked polyurethane resin includes the following steps: Step 1: 15 parts by weight of castor oil polyol (hydroxyl value 225 mgKOH / g, functionality 3) and 70.8 parts by weight of PO3G polyol (hydroxyl value 56.1 mgKOH / g) were placed under vacuum at 120°C for 2 hours. Step 2: Purge with nitrogen to restore room temperature, then adjust the temperature to 55℃. Under nitrogen protection, add 0.09 parts by weight of antioxidant 1010 and 0.01 parts by weight of antioxidant 168, and stir at 300 rpm for 5 minutes. After mixing thoroughly, add 12.4 parts by weight of TDI-80, adjust the temperature to 80℃, and maintain a constant temperature of 80℃ for 120 minutes. Then add 0.1 parts by weight of organic bismuth catalyst BiCAT8124, and continue the reaction at a constant temperature of 80℃ for 60 minutes. n, sampling and testing showed that the -NCO% content of the material in the system reached the theoretical value (0.5%). 0.9 parts of methyl ethyl ketone oxime were added, and the temperature was adjusted to 90℃ and reacted for 60 min. Sampling and testing showed that the -NCO% content of the material was 0, that is, there was no NCO characteristic peak in the infrared test. Then, 0.1 parts by weight of defoamer BYK-A530 and 0.4 parts by weight of leveling agent BYK-UV3500 were added, and the mixture was stirred at 300 rpm for 30 min to obtain a bio-based solvent-free blocked polyurethane prepolymer. Step 3: Mix the bio-based solvent-free blocked polyurethane prepolymer and the diamino-terminated polysiloxane Cheersil 8110 at a mass ratio of 100:6 to obtain an ultra-soft bio-based solvent-free blocked polyurethane resin mixture, which is ready for use.

[0049] The difference between Example 6 and Example 5 is that the ultra-soft bio-based solvent-free blocked polyurethane resin is composed of 100 parts by weight of bio-based blocked polyurethane prepolymer and 12 parts by weight of diamino-terminated polysiloxane Cheersil 8120 with a molecular weight of 2000.

[0050] The difference between Comparative Example 1 and Example 1 is that the blocked polyurethane resin is composed of 100 parts of petroleum-based blocked polyurethane prepolymer and 2.4 parts of 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM) (Jiangsu Qingquan Chemical Co., Ltd.).

[0051] The closed-cell polyurethane prepolymer was prepared from 15 parts by weight of polyether polyol PPG (hydroxyl value 225 mgKOH / g, functionality 3, GY-750P from Guodu Chemical Co., Ltd.), 69 parts by weight of polyether polyol PPG (hydroxyl value 56 mgKOH / g, functionality 2, DP-2000P from Guodu Chemical Co., Ltd.), 13.3 parts by weight of TDI-80 (Bluestar Chemical Co., Ltd.), 1.8 parts by weight of methyl ethyl ketone oxime (Jinan Huifengda Chemical Co., Ltd.), 0.1 parts by weight of organic bismuth catalyst BiCAT 8124 (Leading Chemicals, Inc., USA), 0.09 parts by weight of antioxidant 1010 (Aladdin), 0.01 parts by weight of antioxidant 168 (Aladdin), 0.05 parts by weight of UV-531 (Aladdin), 0.1 parts by weight of defoamer BYK-A530 (BYK, Germany), and 0.4 parts by weight of leveling agent BYK-UV3500 (BYK, Germany).

[0052] A method for preparing a petroleum-based solvent-free blocked polyurethane resin includes the following steps: Step 1: 15 parts by weight of polyether polyol PPG (hydroxyl value 225 mgKOH / g, functionality 3) and 69 parts by weight of polyether polyol PPG (hydroxyl value 56 mgKOH / g, functionality 2) were placed under vacuum at 120°C for 2 hours. Step 2: Purge with nitrogen to restore room temperature, then adjust the temperature to 55℃. Under nitrogen protection, add 0.09 parts by weight of antioxidant 1010 and 0.01 parts by weight of antioxidant 168, and stir at 300 rpm for 5 minutes. After mixing thoroughly, add 13.3 parts by weight of TDI-80, adjust the temperature to 80℃, and maintain a constant temperature of 80℃ for 120 minutes. Then add 0.1 parts by weight of organic bismuth catalyst BiCAT8124, and continue to react at a constant temperature of 80℃ for 60 minutes. Sampling and testing showed that the -NCO% content of the material in the system reached the theoretical value (1.0%). 1.8 parts of methyl ethyl ketone oxime were added, and the temperature was adjusted to 90℃ and reacted for 60 min. Sampling and testing showed that the -NCO% content of the material was 0, that is, there was no NCO characteristic peak in the infrared test. Then, 0.1 parts by weight of defoamer BYK-A530 and 0.4 parts by weight of leveling agent BYK-UV3500 were added, and the mixture was stirred at 300 rpm for 30 min to obtain a bio-based solvent-free blocked polyurethane prepolymer. Step 3: Mix the petroleum-based solvent-free blocked polyurethane prepolymer with 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM) at a mass ratio of 100:2.4, and react at 140-150℃ for 5-10 minutes to obtain the solvent-free blocked polyurethane resin.

[0053] The difference between Comparative Example 2 and Comparative Example 1 is that the solvent-free blocked polyurethane resin consists of 100 parts by weight of petroleum-based blocked polyurethane prepolymer and 12 parts by weight of diamino-terminated polysiloxane Cheersil 8110 with a molecular weight of 1000.

[0054] The difference between Comparative Example 3 and Example 1 is that the solvent-free blocked polyurethane resin is composed of 100 parts by weight of bio-based blocked polyurethane prepolymer and 2.4 parts by weight of 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM).

[0055] The difference between Comparative Example 4 and Comparative Example 1 is that the solvent-free blocked polyurethane resin consists of 100 parts by weight of bio-based blocked polyurethane prepolymer and 4.04 parts by weight of aminopropyl dual-terminated polydimethylsiloxane (Guangdong Wengjiang Chemical Reagent Co., Ltd., molecular formula C...). 12 H 34 N2O2Si3).

[0056] The difference between Comparative Example 5 and Example 1 is that the blocked polyurethane resin consists of 100 parts by weight of bio-based blocked polyurethane prepolymer and 60 parts by weight of aminopropyl double-terminated polydimethylsiloxane with a molecular weight of 5000 (molecular weight 5000, functionality 2, Suzhou Qitian New Materials Co., Ltd. Cheersil 8150).

[0057] The difference between Comparative Example 6 and Example 1 is that the solvent-free blocked polyurethane resin is composed of 100 parts by weight of bio-based blocked polyurethane prepolymer and 4.45 parts by weight of self-made amino-terminated polysiloxane.

[0058] The preparation method of amino-terminated polysiloxane is as follows: 1.86 g (0.01 mol) of linear vinyl silicone oil IOTA-273 (molecular weight 186, vinyl content 29%, Anhui Aiyota Silicone Oil Co., Ltd.), 1.62 g (0.021 mol) of β-mercaptoethylamine (Maclean, CAS: 60-23-1, purity 95%), 0.16 g of 2,4-diethylthioxanthone DETX (Aladdin, CAS: 82799-44-8) and 90 g of methyl ethyl ketone were magnetically stirred at 300 rpm for 15 min, and then ultrasonically dispersed under a UV LED lamp with ultrasonic parameters of 40 kHz / 650 W, UV wavelength of 365 nm, and UV intensity of 80 μW / cm². The reaction was carried out at room temperature for 5 min. Then, the methyl ethyl ketone was removed by vacuum distillation, and the mixture was filtered after dehydration treatment with dehydrating agent-4A zeolite powder to obtain amino-terminated polysiloxane.

[0059] The difference between Comparative Example 7 and Example 1 is that the blocked polyurethane resin is composed of 100 parts of petroleum-based blocked polyurethane prepolymer and 1.2 parts of 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM).

[0060] The closed-cell polyurethane prepolymer was prepared from 15 parts by weight of polyether polyol PPG (hydroxyl value 225 mgKOH / g, functionality 3, GY-750P from Guodu Chemical Co., Ltd.), 69 parts by weight of polyether polyol PPG (hydroxyl value 56 mgKOH / g, functionality 2, DP-2000P from Guodu Chemical Co., Ltd.), 12.4 parts by weight of TDI-80 (Bluestar Chemical Co., Ltd.), 0.9 parts by weight of methyl ethyl ketone oxime (Jinan Huifengda Chemical Co., Ltd.), 0.1 parts by weight of organic bismuth catalyst BiCAT 8124 (Leading Chemicals, Inc., USA), 0.09 parts by weight of antioxidant 1010 (Aladdin), 0.01 parts by weight of antioxidant 168 (Aladdin), 0.05 parts by weight of UV-531 (Aladdin), 0.1 parts by weight of defoamer BYK-A530 (BYK, Germany), and 0.4 parts by weight of leveling agent BYK-UV3500 (BYK, Germany).

[0061] A method for preparing a petroleum-based solvent-free blocked polyurethane resin includes the following steps: Step 1: 15 parts by weight of polyether polyol PPG (hydroxyl value 225 mgKOH / g, functionality 3) and 70.8 parts by weight of polyether polyol PPG (hydroxyl value 56.1 mgKOH / g, functionality 2) were placed under vacuum at 120°C for 2 hours. Step 2: Purge with nitrogen to restore room temperature, then adjust the temperature to 55℃. Under nitrogen protection, add 0.09 parts by weight of antioxidant 1010 and 0.01 parts by weight of antioxidant 168, and stir at 300 rpm for 5 minutes. After mixing thoroughly, add 12.4 parts by weight of TDI-80, adjust the temperature to 80℃, and maintain a constant temperature of 80℃ for 120 minutes. Then add 0.1 parts by weight of organic bismuth catalyst BiCAT8124, and continue to react at a constant temperature of 80℃ for 60 minutes. Sampling and testing showed that the -NCO% content of the material in the system reached the theoretical value (0.5%). 0.9 parts of methyl ethyl ketone oxime were added, and the temperature was adjusted to 90℃ and reacted for 60 min. Sampling and testing showed that the -NCO% content of the material was 0, that is, there was no NCO characteristic peak in the infrared test. Then, 0.1 parts by weight of defoamer BYK-A530 and 0.4 parts by weight of leveling agent BYK-UV3500 were added, and the mixture was stirred at 300 rpm for 30 min to obtain a bio-based solvent-free blocked polyurethane prepolymer. Step 3: Mix the petroleum-based solvent-free blocked polyurethane prepolymer with 3,3'-dimethyl-4,4-diaminodicyclohexylmethane (MACM) at a mass ratio of 100:1.2, and react at 140-150℃ for 5-10 minutes to obtain the solvent-free blocked polyurethane resin.

[0062] The difference between Comparative Example 8 and Example 1 is that the solvent-free blocked polyurethane resin consists of 100 parts by weight of bio-based blocked polyurethane prepolymer and 24 parts by weight of diamino-terminated polysiloxane Cheersil 8110 with a molecular weight of 1000.

[0063] The bio-based blocked polyurethane prepolymer was prepared from 15 parts by weight of castor oil polyol (hydroxyl value 225 mgKOH / g, functionality 3, Shanghai Shuyu Chemical Co., Ltd. SY-790), 65.5 parts by weight of PO3G polyol (hydroxyl value 56.1 mgKOH / g, functionality 2, SK Chemicals H2000, South Korea), 15.1 parts by weight of TDI-80 (Bluestar Chemical Co., Ltd.), 3.6 parts by weight of methyl ethyl ketone oxime (Jinan Huifengda Chemical Co., Ltd.), 0.1 parts by weight of organic bismuth catalyst BiCAT 8124 (Leading Chemicals, USA), 0.1 parts by weight of antioxidant 1010 (Aladdin), 0.01 parts by weight of antioxidant 168 (Aladdin), 0.05 parts by weight of UV-531 (Aladdin), 0.1 parts by weight of defoamer BYK-A530 (BYK, Germany), and 0.4 parts by weight of leveling agent BYK-UV3500 (BYK, Germany).

[0064] A method for preparing an ultra-soft, bio-based, solvent-free, blocked polyurethane resin includes the following steps: Step 1: 15 parts by weight of castor oil polyol (hydroxyl value 225 mgKOH / g, functionality 3) and 65.5 parts by weight of PO3G polyol (hydroxyl value 56.1 mgKOH / g) were placed under vacuum at 120°C for 2 hours. Step 2: Purge with nitrogen to restore room temperature, then adjust the temperature to 55℃. Under nitrogen protection, add 0.09 parts by weight of antioxidant 1010 and 0.01 parts by weight of antioxidant 168, and stir at 300 rpm for 5 minutes. After mixing thoroughly, add 15.1 parts by weight of TDI-80, adjust the temperature to 80℃, and maintain a constant temperature of 80℃ for 120 minutes. Then add 0.1 parts by weight of organic bismuth catalyst BiCAT8124, and continue to react at a constant temperature of 80℃ for 60 minutes. Sampling and testing showed that the -NCO% content of the material in the system reached the theoretical value (2.0%). 3.6 parts of methyl ethyl ketone oxime were added, and the temperature was adjusted to 90℃ and reacted for 60 min. Sampling and testing showed that the -NCO% content of the material was 0, that is, there was no NCO characteristic peak in the infrared test. Then, 0.1 parts by weight of defoamer BYK-A530 and 0.4 parts by weight of leveling agent BYK-UV3500 were added, and the mixture was stirred at 300 rpm for 30 min to obtain a bio-based solvent-free blocked polyurethane prepolymer. Step 3: Mix the bio-based solvent-free blocked polyurethane prepolymer and the diamino-terminated polysiloxane Cheersil 8110 at a mass ratio of 100:24 to obtain an ultra-soft bio-based solvent-free blocked polyurethane resin mixture.

[0065] Performance testing: 1. 100% Modulus Test Method: Cut the prepared film into rectangular samples of 20mm*100mm using a utility knife. Measure the thickness at three points using a thickness gauge and calculate the average value. Clamp the cut sample onto a universal tensile testing machine as specified, with a 50mm gap between the upper and lower clamps. Start the tensile testing machine at a constant speed of 100mm / min. When the sample is stretched to 100mm, record the tensile force (in N). 100% Modulus: Modulus = Tensile force at 100% displacement / (Sample thickness * Sample width).

[0066] 2. Rebound Rate Test Method: Cut the prepared membrane into rectangular samples of 20mm*100mm using a utility knife. Measure the thickness at three points using a thickness gauge and calculate the average value. Clamp the cut sample onto a universal tensile testing machine as specified, with a 50mm gap between the upper and lower clamps. Start the tensile testing machine at a constant speed of 100mm / min. When the sample is stretched to 100mm, hold for 10 minutes. Then unload the membrane, let it stand for 10 minutes, and measure the recovered membrane length L. The formula for calculating the membrane's tensile rebound rate is: (100-L) / 50.

[0067] 2. Peel strength was determined in accordance with ISO 11339:2022 "Adhesives - T-peel test for flexible to flexible bonded components".

[0068] 3. Jungle test method: The leather is placed in a constant temperature and humidity aging chamber and placed at 70℃ and 95% humidity for 5 weeks. Then it is taken out and subjected to peel strength test (ISO 11339:2022).

[0069] 4. Cold resistance test: The leather is placed at -20℃ and subjected to 80,000 bends. The appearance quality of the leather surface is then observed.

[0070] Table 1: Performance Test Parameters of Examples 1-6 and Comparative Examples 1-8

[0071] As can be seen from Examples 1-4, Example 6, Comparative Examples 1 and 3, and Table 1, when the present invention uses diamine-modified polysiloxane for post-chain extension and controls the NCO% before resin sealing to be in the range of 0.5-1.0%, the modulus of the PU film is significantly lower than that of PU films prepared with existing diamine curing agents, giving it a full, soft feel and environmental friendliness. As can be seen from Examples 1 and Comparative Example 8, when the NCO% before resin sealing is too low, the R value is close to 1, which leads to excessively high resin viscosity, or even explosive polymerization; while when the NCO% before resin sealing is too high, the modulus of the PU film is too high, resulting in a harder feel.

[0072] Based on Examples 1-6, Comparative Examples 2, 4, and 5, and in conjunction with Table 1, it can be seen that the mass ratio of amino-terminated polysiloxane to blocked polyurethane prepolymer should ideally be controlled at (6-25):100. If the molecular weight of diamino-terminated polysiloxane is too low, the feel will be too hard, the modulus will be too high, and excellent softness will not be achieved. The low-temperature cold resistance will also be poor. On the other hand, if the molecular weight of diamino-terminated polysiloxane is too high, the feel will be too soft, the film will have poor elasticity, and the abrasion resistance, resilience, and peel strength will be low.

[0073] As can be seen from Example 4 and Comparative Example 6, and Table 1, the low molecular weight of the self-made diamino-terminated polysiloxane also leads to a hard PU film that cannot achieve excellent softness.

[0074] Combining Examples 1 and 4 with Table 1, it can be seen that the self-made diamino-terminated polysiloxane in Example 4 can improve the peel strength between the PU film or leather and the surface layer while ensuring the wear resistance, weather resistance, mechanical properties, and cold resistance of the PU film or leather. This is beneficial for improving the adhesion stability and service life of the leather.

[0075] It should be noted that this specific embodiment is merely an explanation of the technical solution of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. An ultra-soft, bio-based, solvent-free, blocked polyurethane resin, characterized in that: It includes a blocked polyurethane prepolymer and an amino-terminated polysiloxane with a molecular weight of 800-2000; the mass ratio of the amino-terminated polysiloxane with a molecular weight of 800-2000 to the blocked polyurethane prepolymer is (6-25):

100.

2. The ultra-soft, bio-based, solvent-free, blocked polyurethane resin according to claim 1, characterized in that: The closed-cell polyurethane prepolymer is made from the following raw materials in parts by weight: 10-20 parts of diisocyanate, 80-90 parts of bio-based polyol, 1.5-3.0 parts of blocker, 0.05-0.20 parts of catalyst, 0.05-0.20 parts of defoamer, 0.2-0.5 parts of leveling agent, and 0.05-0.20 parts of anti-aging agent.

3. The ultra-soft, bio-based, solvent-free, blocked polyurethane resin according to claim 2, characterized in that: The bio-based polyols include castor oil polyols and PO3G polyols. The hydroxyl value of castor oil polyols is 80-300 mgKOH / g, and the hydroxyl value of PO3G polyols is 35-120 mgKOH / g.

4. The ultra-soft, bio-based, solvent-free, blocked polyurethane resin according to claim 3, characterized in that: The molar ratio of castor oil polyol to PO3G polyol is (4-6):

10.

5. The ultra-soft, bio-based, solvent-free, blocked polyurethane resin according to claim 2, characterized in that: The diisocyanate is at least one of TDI-80, TDI-100, TDI-65, MDI-100, MDI-50, carbodiimide-modified MDI-100HL, and carbodiimide-modified MDI-100LL.

6. The ultra-soft, bio-based, solvent-free, blocked polyurethane resin according to claim 2, characterized in that: The blocking agent is at least one of acetanilide, methyl ethyl ketone oxime, 3,5-dimethylpyrazole, 1,2,4-triazole, acetylacetone, butanone oxime, and acetone oxime.

7. The ultra-soft, bio-based, solvent-free, blocked polyurethane resin according to claim 2, characterized in that: The catalyst is an organic bismuth and / or an organic zinc; the organic bismuth is at least one of bismuth isooctanoate BiCAT 8118, BiCAT 8108, and BiCAT 8124; the organic zinc is at least one of zinc isooctanoate 825-1, zinc isooctanoate 825-4, zinc isooctanoate 825-12, and zinc isooctanoate BiCAT ZM.

8. The ultra-soft, bio-based, solvent-free, blocked polyurethane resin according to claim 2, characterized in that: The defoamer is a silicone-based defoamer, and the silicone-based defoamer is at least one of BYK-060N, BYK-066N, and BYK-A530; the leveling agent is any one of BYK-UV3510, BYK-UV3500, TEGO Flow300, TEGO Rad2200N, and TEGORad2100.

9. The ultra-soft, bio-based, solvent-free, blocked polyurethane resin according to claim 2, characterized in that: The anti-aging agent includes an antioxidant and an anti-ultraviolet agent. The antioxidant is at least one of antioxidant BHT, antioxidant 245, antioxidant 1010, antioxidant 1035, antioxidant 1076, antioxidant 1098, antioxidant 3114, and antioxidant 168. The anti-ultraviolet agent is at least one of UV-292, UV-622, UV-770, UV-944, UV-5050, UV-5060, UV-5151, UV-531, and UV-327.

10. A method for preparing an ultra-soft, bio-based, solvent-free, blocked polyurethane resin according to any one of claims 1-9, characterized in that: Includes the following steps: Step 1: Vacuum dehydration treatment of bio-based polyols; Step 2: Under nitrogen protection, the vacuum-dehydrated bio-based polyol and anti-aging agent are mixed evenly, the temperature is adjusted to 50-60℃, diisocyanate is added, and the reaction is carried out at 80-85℃ for 100-135 min. Then, a catalyst is added, and the reaction is carried out at 80-95℃ for 50-75 min. The sample is taken for testing, and the -NCO% content of the material in the system reaches the theoretical value, which is 0.5-1.0%. A blocking agent is added, and the reaction is carried out at 80-90℃ for 50-75 min. The sample is taken for testing, and the -NCO% content of the material is 0. Then, a defoamer and a leveling agent are added, and the mixture is stirred for 15-45 min to obtain a bio-based solvent-free blocked polyurethane prepolymer. Step 3: Mix the bio-based solvent-free blocked polyurethane prepolymer and amino-terminated polysiloxane at a mass ratio of (10-25):100 to obtain the ultra-soft bio-based solvent-free blocked polyurethane resin.

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