A composition of an isocyanate prepolymer which is stable in storage and a method for preparing the same

Abstract

The present application provides a kind of isocyanate prepolymer composition and its preparation method which can be stably stored.The composition contains isocyanate prepolymer, phosphine compound.The phosphine compound does not react with isocyanate in the system, and can capture basic or metal catalyst in the prepolymer compound system to deactivate it, reduce the further reaction of isocyanate and carbamate / uretonimine crosslinking, and further reduce the generation of macromolecular polymer, reduce the viscosity and composition change of product, and thus improve the storage stability of product.

Description

Technical Field

[0001] This invention belongs to the field of isocyanates, specifically relating to a composition of a stable isocyanate prepolymer and its preparation method. Background Technology

[0002] Isocyanates are raw materials for polyurethane, primarily prepared through the phosgenation of corresponding amines. Organic amines react with phosgene to yield isocyanates, which, based on their chemical structure, are classified into aromatic isocyanates and aliphatic isocyanates. These are reacted with different polyols to produce polyurethane materials with varying properties, including foams and elastomers. Due to the high reactivity of isocyanate groups, they can react with primary / hydroxyl and secondary amine compounds under heating and alkaline catalysis. Whether based on aromatic isocyanates, aliphatic isocyanates, carbodiimide-modified isocyanates, or urethane-modified isocyanates reacting with polyols containing active hydrogen to obtain one or more isocyanate prepolymers, under heating and alkaline or metal catalyst catalysis, the isocyanate reacts with the secondary amine groups in the urethane to form large-molecule cross-linked compounds. This results in the loss of NCO (isocyanate groups) in the product, while simultaneously increasing the viscosity of the liquid product, leading to product deterioration and, in severe cases, solidification. In isocyanate prepolymers obtained by reacting isocyanates with polyols containing active hydrogen, abnormal product viscosity and NCO levels, and even reactor solidification, often occur during production due to high reactivity. During storage and transportation, these issues lead to increased product viscosity and decreased NCO. The instability of isocyanate-based prepolymers is mainly due to catalyst residue in the polyols containing active hydrogen, and this is more likely to occur in high-temperature environments. If the catalyst content exceeds the limit, the isocyanate reacts with urethane to form cross-linked macromolecules, causing product deterioration and economic losses.

[0003] In summary, there is an urgent need in this field to improve the storage stability of isocyanate prepolymers and reduce the risk of deterioration during production, storage and transportation. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method for improving the storage stability of isocyanate prepolymers, which can improve the storage stability of isocyanate prepolymers and reduce the risk of deterioration during production, storage and transportation.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A composition of an isocyanate prepolymer, the composition comprising an isocyanate prepolymer and a phosphononitrile compound; wherein the weight ratio of the phosphononitrile compound to the isocyanate compound is (0.001-1.0):100, preferably (0.003-0.01):100.

[0007] In this field, the catalysts used in polyether polyols are mainly alkaline catalysts, such as KOH, while those used in polyester polyols are mainly metal catalysts, such as tetrabutyl titanate. If the residual catalyst concentration exceeds 1 ppm during polyol production, the residual catalyst accelerates the reaction between the polyol and isocyanate, and catalyzes the reaction between isocyanate and urethane to form cross-linked macromolecules, leading to product deterioration. The inventors have discovered that phosphononitriles, due to their central electron-deficient structure, are strongly acidic Lewis acids that readily capture alkaline substances. When added to isocyanate, they can bind with the catalyst during the prepolymerization reaction, rendering it inactive and reducing the catalyst concentration, thereby reducing reactivity and extending shelf life.

[0008] In one embodiment of the present invention, the isocyanate prepolymer is a prepolymer obtained by reacting isocyanate with a polyol containing active hydrogen; preferably, the isocyanate is one or more of aliphatic isocyanate, alicyclic isocyanate, aromatic isocyanate, and compounds containing the above isocyanate structure, preferably one or more of diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, urethane-modified isocyanate, and carbodiimide-modified isocyanate; preferably, the polyol containing active hydrogen is one or more of 2-3 nucleotide polyethers or polyester polyols with a molecular weight of 100-3000, preferably one or more of C2020, PBA2000, C1010, and PTMG2000.

[0009] In one embodiment of the present invention, the phosphazene compound has the following structure:

[0010]

[0011] Wherein, R is an alkoxy group of C1-C18 and / or chlorine, preferably one or more of C1-C3 alkoxy groups.

[0012] In one embodiment of the present invention, the phosphazene compound comprises hexachlorophosphazene and / or a phosphazene compound obtained by a substitution reaction of hexachlorophosphazene with a C1-C18 primary sodium alkoxide.

[0013] Another object of the present invention is to provide a method for preparing a composition of isocyanate prepolymer.

[0014] A method for preparing a composition of isocyanate prepolymer, wherein the composition is the above-mentioned composition of isocyanate prepolymer, and the preparation method involves adding a phosphononitrile compound during the isocyanate prepolymerization process.

[0015] Another object of the present invention is to provide a method for preparing phosphononitrile compounds.

[0016] A method for preparing a phosphononitrile compound, wherein the compound is the phosphononitrile compound described above, the method comprising the following steps:

[0017] The primary sodium alkoxide (C1-C18) was reacted with hexachlorophosphononitrile in a solvent, washed with water to obtain the crude product, and recrystallized to obtain the phosphononitrile compound.

[0018] In one embodiment of the present invention, the molar ratio of primary sodium alkoxide to hexachlorophosphononitrile in the method is (6.0-6.6):1.

[0019] Another object of the present invention is to provide the use of a composition of isocyanate prepolymer.

[0020] Use of an isocyanate prepolymer composition, wherein the composition is the isocyanate prepolymer composition described above, or a composition prepared by the above preparation method, wherein the composition is used as an isocyanate prepolymer with high storage stability, preferably as a raw material prepolymer for the production of polyurethane adhesives, coatings, and flexible foams.

[0021] Compared with the prior art, the positive effects of the present invention are as follows:

[0022] The addition of phosphononitrile compounds to isocyanates reduces the reactivity of the isocyanate compounds, making them compatible with polyols of different reactivity. This makes the reaction process controllable, and the resulting prepolymers have more stable storage performance. In particular, the prepolymers prepared from highly active polyols have a shelf life that is extended by more than six times. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the embodiments.

[0024] The raw materials are from the following sources, industrial grade:

[0025] MDI-50 Wanhua Chemical Group Co., Ltd.

[0026] MDI-100 Wanhua Chemical Group Co., Ltd.

[0027] HDI Wanhua Chemical Group Co., Ltd.

[0028] Polyether polyol C2020 Wanhua Chemical Group Co., Ltd.

[0029] Polyester polyol PBA2000, Wanhua Chemical Group Co., Ltd.

[0030] TDI-80 Wanhua Chemical Group Co., Ltd.

[0031] Beijing Innocare Technology Co., Ltd. (Hexachlorophosphononitrile)

[0032] Instruments and equipment:

[0033] Potentiometric titrator, METTLER TOLEOO, model: 905Titrando;

[0034] Viscometer, BROOKFIELD, Model: DV2TLVTJO;

[0035] Nuclear magnetic resonance spectrometer, Bruker GmbH, Germany, model: Bruker AvanceⅢ500 / 400MHz;

[0036] High-resolution direct injection time-of-flight mass spectrometer, Micromass, UK, model: GCT.

[0037] Preparation Example 1

[0038] Dissolve 10g KOH in 20g water to prepare a KOH aqueous solution with a mass fraction of 33.3%. Take 0.025g of the above KOH aqueous solution and add it to 1000g C2020 to prepare a highly active C2020 with a K ion concentration of 5ppm.

[0039] Preparation Example 2

[0040] Dissolve 20g of tetrabutyl titanate in 20g of propylene glycol to prepare a 50% (w / w) tetrabutyl titanate propylene glycol solution. Add 0.07g of the above tetrabutyl titanate propylene glycol solution to 1000g of PBA2000 to prepare a highly active PBA2000 with a titanium ion concentration of 5ppm.

[0041] Preparation Example 3

[0042] Sodium octadecyloxide was dissolved in acetone and placed in a reaction vessel. The mixture was heated to 55°C and refluxed. A solution of hexachlorophosphononitrile in acetone was then added dropwise to the reaction vessel, with a molar ratio of hexachlorophosphononitrile to sodium alkoxide of 1:6.5. The reaction was refluxed for 48 hours. After the reaction was complete, the solvent was removed, and the mixture was washed with water to obtain the crude product. The crude product was then heated with ethanol to reflux, stirred for 2 hours, cooled to room temperature, and filtered to obtain the final product.

[0043] Preparation Example 4

[0044] Sodium ethoxide was dissolved in acetone and placed in a reaction vessel. The mixture was heated to 55°C and refluxed. A solution of hexachlorophosphononitrile in acetone was then added dropwise to the reaction vessel, with a molar ratio of hexachlorophosphononitrile to sodium ethoxide of 1:6.5. The mixture was refluxed for 30 hours. After the reaction was complete, the solvent was removed, and the product was washed with water to obtain the crude product. The crude product was then heated with ethanol to reflux, stirred for 2 hours, cooled to room temperature, and filtered to obtain the final product.

[0045] The hexa(ethoxy)cyclophosphononitrile prepared in this preparation example was characterized, and the results are as follows: 1H NMR(400MHz, DMSO)δ4.01(p,J=8.6Hz,12H),1.2(t,J=7.3Hz,18H).TOF-EI-MS(m / z):calcd.forC 12 H 30 N3O6P3 405.1335,found 405.1308[M + ].

[0046] Example 1

[0047] Take 1g of hexa(octadecyloxy)cyclophosphononitrile from Preparation Example 2 and add it to 1000g of MDI-100. After stirring evenly, take 449g and place it in a four-necked flask. Keep the temperature constant in an oil bath at 55°C. When the material temperature reaches 50°C, add 835g of the highly reactive C2020 obtained in Preparation Example 1 to the flask, start mechanical stirring, and raise the material temperature to 80°C through the oil bath. React at this temperature for 3 hours. The product is a prepolymer with an NCO content of 9.01%.

[0048] Weigh 100g of the prepolymer into a 100mL glass bottle and store it in a constant temperature and humidity chamber at 35℃ and 40% humidity to test the shelf life of the sample. After 30 days and 100 days, test the viscosity and NCO of the sample to obtain the shelf life data. The viscosity test method refers to GB / T 10247-2008, and the NCO test method refers to GB / T 9725-2007.

[0049] Example 2

[0050] Take 0.05g of hexa(ethoxy)cyclophosphonium from Preparation Example 2 and add it to 1000g of MDI-100. After stirring evenly, take 449g and place it in a four-necked flask. Keep the temperature constant in an oil bath at 55°C. When the material temperature reaches 50°C, add 835g of the highly reactive C2020 obtained in Preparation Example 1 to the flask, start mechanical stirring, and raise the material temperature to 80°C through the oil bath. React at this temperature for 3 hours. The product is a prepolymer with an NCO content of 9.01%.

[0051] Weigh 100g of prepolymer into a 100mL glass bottle and store it in a constant temperature and humidity chamber at 35℃ and 40% for shelf life testing. After 30 days and 100 days, test the viscosity and NCO of the sample to obtain the shelf life data.

[0052] Example 3

[0053] 0.05g of hexachlorophosphononitrile was added to 1000g of TDI-80 and stirred until homogeneous. 125g of this mixture was placed in a four-necked flask and kept at a constant temperature of 55°C in an oil bath. When the material temperature reached 50°C, 537g of the highly reactive C2020 obtained in Preparation Example 1 was added to the flask. Mechanical stirring was started, and the material temperature was raised to 80°C using the oil bath. The reaction was carried out at this temperature for 3 hours. The product was a prepolymer with an NCO content of 9.03%. 100g of the prepolymer was weighed using a 100mL glass bottle and stored in a constant temperature and humidity chamber at 35°C and 40% humidity for shelf-life testing. The appearance of the samples was observed after 30 days and 100 days, and the viscosity and NCO content were tested to obtain the shelf-life data.

[0054] Example 4

[0055] 0.05 g of hexa(ethoxy)phosphononitrile was added to 1000 g of HDI and stirred until homogeneous. 125 g of the mixture was placed in a four-necked flask and kept at a constant temperature of 55°C in an oil bath. When the material temperature reached 50°C, 561 g of the highly reactive C2020 obtained in Preparation Example 1 was added to the flask. Mechanical stirring was started, and the material temperature was raised to 80°C using the oil bath. The reaction was carried out at this temperature for 3 hours. The product was a prepolymer with an NCO content of 9.03%. 100 g of the prepolymer was weighed using a 100 mL glass bottle and stored in a constant temperature and humidity chamber at 35°C and 40% humidity for shelf-life testing. The appearance of the sample was observed after 30 days and 100 days, and the viscosity and NCO content were tested to obtain the shelf-life data.

[0056] Example 5

[0057] 0.05 g of hexa(ethoxy)phosphononitrile was added to 1000 g of MDI-100 and stirred until homogeneous. 125 g of the mixture was placed in a four-necked flask and kept at a constant temperature of 55°C in an oil bath. When the material temperature reached 50°C, 561 g of the highly reactive PBA2000 obtained in Preparation Example 2 was added to the flask. Mechanical stirring was started, and the material temperature was raised to 80°C using the oil bath. The reaction was carried out at this temperature for 3 hours. The product was a prepolymer with an NCO content of 9.03%. 100 g of the prepolymer was weighed using a 100 mL glass bottle and stored in a constant temperature and humidity chamber at 35°C and 40% humidity for shelf-life testing. The appearance of the sample was observed after 30 days and 100 days, and the viscosity and NCO content were tested to obtain the shelf-life data.

[0058] Comparative Example 1

[0059] Compared with Example 1, the only difference is that no phosphazene adjuvants were added; all other operations were the same.

[0060] Comparative Example 2

[0061] Compared with Example 3, the only difference is that no phosphazene adjuvants were added; all other operations were the same.

[0062] Comparative Example 3

[0063] Compared with Example 4, the only difference is that no phosphazene adjuvants were added; all other operations were the same.

[0064] Comparative Example 4

[0065] Compared with Example 5, the only difference is that no phosphazene additives were added; all other operations were the same.

[0066] The data from the above examples and comparative examples are shown in the table below. Shelf life tracking shows that the shelf life of prepolymers prepared from isocyanates with added phosphononitrile additives and highly reactive polyols can be extended by more than 6 times, indicating that phosphononitrile additives have a positive effect on extending the shelf life of prepolymers. Among them, hexa(ethoxy)phosphononitrile showed the best effect in extending the shelf life of prepolymers due to its good nucleophilicity, small steric hindrance, and strong molecular stability.

[0067] Adding phosphononitrile stabilizers to isocyanate compounds and preparing prepolymers with polyols allows the phosphononitrile compounds in the system to capture the catalyst introduced during the polyol production process. This prevents the catalyst from catalyzing the reaction between isocyanate and urethane to form cross-linked macromolecules during storage, thus preventing product deterioration. It also improves the compatibility of isocyanate compounds with different active polyols and enhances the storage stability of isocyanate prepolymers.

[0068]

[0069] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A composition of an isocyanate prepolymer, characterized in that, The composition contains isocyanate prepolymer and phosphononitrile compound; The isocyanate prepolymer is a prepolymer obtained by reacting isocyanate with a polyol containing active hydrogen. The weight ratio of the phosphononitrile compound to the isocyanate is (0.001~1.0):100; The structure of the phosphazene compound is as follows: Wherein, R is a C1-C18 alkoxy group and / or chlorine; The composition incorporates phosphononitrile compounds during the isocyanate prepolymerization process.

2. The composition according to claim 1, characterized in that, The weight ratio of the phosphononitrile compound to the isocyanate is (0.003~0.01):

100.

3. The composition according to claim 1, characterized in that, The isocyanate is one or more of aliphatic isocyanates, alicyclic isocyanates, aromatic isocyanates, and compounds containing the above isocyanate structures; The active hydrogen-containing polyol is one or more of 2-3 nucleotide polyethers or polyester polyols with a molecular weight of 100-3000.

4. The composition according to claim 3, characterized in that, The isocyanate is one or more selected from diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, urethane-modified isocyanate, and carbodiimide-modified isocyanate. The active hydrogen-containing polyol is one or more of C2020, PBA2000, C1010, and PTMG2000.

5. The composition according to claim 1 or 2, characterized in that, In the structure of the phosphononitrile compound, R is one or more alkoxy groups from C1 to C3.

6. The composition according to claim 5, characterized in that, The phosphazene compounds include hexachlorophosphazene and / or phosphazene compounds obtained by substitution reaction of hexachlorophosphazene with C1-C18 primary sodium alkoxide.

7. A method for preparing a composition of an isocyanate prepolymer, wherein the composition is the isocyanate prepolymer composition according to any one of claims 1-6, characterized in that, The preparation method involves adding a phosphononitrile compound during the isocyanate prepolymerization process.

8. The preparation method according to claim 7, characterized in that, The method for preparing the phosphazene compound comprises the following steps: The primary sodium alkoxide (C1-C18) was reacted with hexachlorophosphononitrile in a solvent, washed with water to obtain the crude product, and recrystallized to obtain the phosphononitrile compound.

9. The preparation method according to claim 8, characterized in that, In the method for preparing the phosphazene compound, the molar ratio of primary sodium alkoxide to hexachlorophosphazene is (6.0-6.6):

1.

10. Use of a composition of an isocyanate prepolymer, said composition being a composition of an isocyanate prepolymer according to any one of claims 1-6, or a composition prepared by any one of claims 7-9, said composition being used as an isocyanate prepolymer with high storage stability.

11. The use according to claim 10, characterized in that, The composition is used as a raw material prepolymer for the production of polyurethane adhesives, coatings, and flexible foams.

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