Catalyst for synthesizing rigid polyurethane and preparation method thereof

Abstract

The invention belongs to the technical field of polyurethane synthesis, and particularly relates to a catalyst for synthesizing hard polyurethane and a preparation method of the catalyst. According to the catalyst, bismuth iso-octoate is taken as a matrix, hydroxypropyl methyl cellulose is firstly adsorbed on the surface of bismuth iso-octoate, and then 2-aminoterephthalic acid and bismuth iso-octoate are complexed at a certain temperature, so that the bismuth iso-octoate can better exert catalytic activity and selectivity, and the generation of byproducts is inhibited; furthermore, a polyurethane product has excellent mechanical properties, and the catalyst is more suitable for preparing a hard polyurethane material.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane synthesis, and particularly relates to a catalyst for synthesizing rigid polyurethane and a preparation method thereof. Background Art

[0002] Rigid polyurethane material is a material that does not deform significantly under a certain load, and cannot return to its original state after deformation under excessive load. It is a high-molecular polymer made of isocyanate and polyether as the main raw materials, catalyzed by a catalyst at a certain temperature, and foamed on-site by high-pressure spraying. It has excellent mechanical properties, acoustic properties, electrical properties, chemical properties and low thermal conductivity, and has been widely used in many fields such as automobiles, construction, electronics, and medical devices.

[0003] In the preparation process of rigid polyurethane materials, bismuth isooctanoate catalyst is one of the commonly used catalysts. Although bismuth isooctanoate catalyst is greener and safer than tin catalysts, it has the problems of low catalytic activity and many by-products, which leads to the decrease of mechanical properties of the finally prepared rigid polyurethane material. When used as a material in a load-bearing structure, it often fails to meet the requirements. Summary of the invention

[0004] Aiming at the problem that in the prior art, when bismuth isooctanoate is used to catalyze the synthesis of rigid polyurethane materials, the catalytic activity is low and many by-products are produced, resulting in that the mechanical properties of the prepared rigid polyurethane materials cannot meet the requirements, the present invention provides a catalyst for synthesizing rigid polyurethane. The catalyst uses bismuth isooctanoate as a matrix, firstly uses hydroxypropyl methylcellulose to adsorb on the surface of the bismuth isooctanoate, and then allows 2-aminoterephthalic acid and the bismuth isooctanoate to undergo complexation at a certain temperature, so that the bismuth isooctanoate can better exert its catalytic activity and selectivity, inhibit the generation of by-products, and then the polyurethane product obtains excellent mechanical properties. The catalyst is more suitable for preparing rigid polyurethane materials.

[0005] The first aspect of the present invention provides a method for preparing a catalyst for synthesizing rigid polyurethane, comprising the following steps: S1: dissolving a bismuth salt in a nitric acid solution to form a solution A; S2: dissolving hydroxypropyl methylcellulose, isooctanoic acid and polyvinyl pyrrolidone in ethylene glycol and stirring thoroughly to obtain solution B; S3: Slowly drop solution A into solution B, stir and mix thoroughly, then place in a high pressure reactor for a first solvothermal reaction to obtain a precursor; S4: dispersing the precursor in a mixed solution of 2-aminoterephthalic acid and methanol, placing the mixture in a high-pressure reactor for a second solvent thermal reaction, and then washing and filtering to obtain a catalyst for synthesizing rigid polyurethane.

[0006] Furthermore, in step S1, the bismuth salt is at least one of bismuth nitrate pentahydrate and bismuth acetate.

[0007] Furthermore, in step S1, the concentration of the nitric acid solution is 1-2 mol / L, and the addition ratio of the bismuth salt to the nitric acid solution is 0.01 mol:50-80 mL.

[0008] Furthermore, the ratio of bismuth salt, hydroxypropyl methylcellulose, isooctanoic acid, polyvinyl pyrrolidone and ethylene glycol is 0.01 mol: 0.001 mol: 0.03 mol: 0.001 mol: 50-80 mL.

[0009] Furthermore, in step S3, the first solvent thermal reaction temperature is 160-180° C., and the reaction time is 6-8 h.

[0010] Furthermore, in step S4, the addition ratio of 2-aminoterephthalic acid and methanol is 1~2g:30~50mL.

[0011] Furthermore, in step S4, the addition ratio of the precursor to the mixed solution of 2-aminoterephthalic acid and methanol is 3-5 g:30-50 mL.

[0012] Furthermore, in step S4, the second solvent thermal reaction temperature is 120-130° C., and the reaction time is 6-8 h.

[0013] Furthermore, in step S4, the second solvent thermal reaction temperature is 120° C. and the reaction time is 7 h.

[0014] The second aspect of the present invention provides a catalyst for synthesizing rigid polyurethane prepared by the method for preparing the catalyst for synthesizing rigid polyurethane.

[0015] The beneficial effects achieved by one or more technical solutions of the present invention are as follows: 1. The present invention uses hydroxypropyl methylcellulose to be adsorbed on the surface of bismuth isooctanoate, which can effectively prevent the agglomeration of bismuth isooctanoate, thereby achieving a dispersion stabilization effect, so that it can better exert catalytic activity. At the same time, hydroxypropyl methylcellulose can effectively improve the molding strength of the catalyst by virtue of structural specificity, inhibit the catalyst from pulverizing and breaking during the reaction process of synthesizing polyurethane, thereby extending the service life of the catalyst, and can also stabilize the relative speed of the reaction well, so the stability of the product polyurethane growth is better and the mechanical strength is higher.

[0016] There is a strong complexation between 2.2-aminoterephthalic acid and bismuth isooctanoate. 2-aminoterephthalic acid can be evenly complexed around bismuth isooctanoate, which can not only inhibit the hydrolysis and deterioration of bismuth isooctanoate and improve the stability of bismuth isooctanoate, but also further enhance the catalytic activity and selectivity of bismuth isooctanoate, inhibit the generation of by-product molecules and their inclusion in polyurethane products, and thus the prepared hard polyurethane material can obtain excellent mechanical properties. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments and comparative examples.

[0018] Example 1 This embodiment provides a method for preparing a catalyst for synthesizing rigid polyurethane, and the specific steps are as follows: S1: dissolving 4.85 g of bismuth nitrate pentahydrate in 50 mL of nitric acid solution having a concentration of 1 mol / L to form solution A; S2: Dissolve hydroxypropyl methylcellulose, isooctanoic acid, and polyvinyl pyrrolidone in ethylene glycol, wherein the ratio of bismuth nitrate pentahydrate, hydroxypropyl methylcellulose, isooctanoic acid, polyvinyl pyrrolidone, and ethylene glycol is 0.01 mol: 0.001 mol: 0.03 mol: 0.001 mol: 50 mL, and stir well to obtain solution B; S3: Slowly drop solution A into solution B, stir and mix thoroughly, then place in a high pressure reactor for the first solvothermal reaction at a reaction temperature of 160° C. for 8 h to obtain a precursor; S4: Dissolve 2 g of 2-aminoterephthalic acid in 50 mL of methanol, and then disperse 5 g of the precursor in 50 mL of a mixed solution of 2-aminoterephthalic acid and methanol, and place in a high-pressure reactor for a second solvent thermal reaction at a reaction temperature of 120°C for 7 hours, then wash and filter to obtain a catalyst for synthesizing rigid polyurethane.

[0019] Example 2 This embodiment provides a method for preparing a catalyst for synthesizing rigid polyurethane, and the specific steps are as follows: S1: dissolving 4.85 g of bismuth nitrate pentahydrate in 80 mL of nitric acid solution having a concentration of 1 mol / L to form solution A; S2: Dissolve hydroxypropyl methylcellulose, isooctanoic acid, and polyvinyl pyrrolidone in ethylene glycol, wherein the ratio of bismuth nitrate pentahydrate, hydroxypropyl methylcellulose, isooctanoic acid, polyvinyl pyrrolidone, and ethylene glycol is 0.01 mol: 0.001 mol: 0.03 mol: 0.001 mol: 50 mL, and stir well to obtain solution B; S3: Slowly drop solution A into solution B, stir and mix thoroughly, then place in a high pressure reactor for the first solvothermal reaction at a reaction temperature of 180° C. for 6 h to obtain a precursor; S4: Dissolve 1 g of 2-aminoterephthalic acid in 30 mL of methanol, and then disperse 5 g of the precursor in 30 mL of a mixed solution of 2-aminoterephthalic acid and methanol, and place in a high-pressure reactor for a second solvent thermal reaction at a reaction temperature of 120°C for 6 hours, then wash and filter to obtain a catalyst for synthesizing rigid polyurethane.

[0020] Example 3 This embodiment provides a method for preparing a catalyst for synthesizing rigid polyurethane, and the specific steps are as follows: S1: dissolving 4.85 g of bismuth nitrate pentahydrate in 50 mL of nitric acid solution having a concentration of 2 mol / L to form solution A; S2: Dissolve hydroxypropyl methylcellulose, isooctanoic acid, and polyvinyl pyrrolidone in ethylene glycol, wherein the ratio of bismuth nitrate pentahydrate, hydroxypropyl methylcellulose, isooctanoic acid, polyvinyl pyrrolidone, and ethylene glycol is 0.01 mol: 0.001 mol: 0.03 mol: 0.001 mol: 80 mL, and stir well to obtain solution B; S3: Slowly drop solution A into solution B, stir and mix thoroughly, then place in a high pressure reactor for the first solvothermal reaction at a reaction temperature of 180° C. for 6 h to obtain a precursor; S4: Dissolve 1 g of 2-aminoterephthalic acid in 30 mL of methanol, and then disperse 3 g of the precursor in 30 mL of a mixed solution of 2-aminoterephthalic acid and methanol, and place in a high-pressure reactor for a second solvent thermal reaction at a reaction temperature of 120°C for 8 hours, then wash and filter to obtain a catalyst for synthesizing rigid polyurethane.

[0021] Example 4 This embodiment provides a method for preparing a catalyst for synthesizing rigid polyurethane, and the specific steps are as follows: S1: dissolving 4.85 g of bismuth nitrate pentahydrate in 50 mL of nitric acid solution having a concentration of 2 mol / L to form solution A; S2: Dissolve hydroxypropyl methylcellulose, isooctanoic acid, and polyvinyl pyrrolidone in ethylene glycol, wherein the ratio of bismuth nitrate pentahydrate, hydroxypropyl methylcellulose, isooctanoic acid, polyvinyl pyrrolidone, and ethylene glycol is 0.01 mol: 0.001 mol: 0.03 mol: 0.001 mol: 50 mL, and stir well to obtain solution B; S3: Slowly drop solution A into solution B, stir and mix thoroughly, then place in a high pressure reactor for the first solvothermal reaction at a reaction temperature of 180° C. for 6 h to obtain a precursor; S4: Dissolve 1 g of 2-aminoterephthalic acid in 50 mL of methanol, and then disperse 3 g of the precursor in 50 mL of a mixed solution of 2-aminoterephthalic acid and methanol, and place in a high-pressure reactor for a second solvent thermal reaction at a reaction temperature of 130°C for 6 hours, then wash and filter to obtain a catalyst for synthesizing rigid polyurethane.

[0022] Comparative Example 1 This comparative example provides a method for preparing a catalyst for synthesizing rigid polyurethane, and the specific steps are as follows: S1: dissolving 4.85 g of bismuth nitrate pentahydrate in 50 mL of nitric acid solution having a concentration of 1 mol / L to form solution A; S2: dissolving isooctanoic acid and polyvinyl pyrrolidone in ethylene glycol, wherein the ratio of bismuth nitrate pentahydrate, isooctanoic acid, polyvinyl pyrrolidone and ethylene glycol is 0.01 mol: 0.03 mol: 0.001 mol: 50 mL, and stirring well to obtain solution B; S3: Slowly drop solution A into solution B, stir and mix thoroughly, then place in a high pressure reactor for the first solvothermal reaction at a reaction temperature of 160° C. for 8 h to obtain a precursor; S4: Dissolve 2 g of 2-aminoterephthalic acid in 50 mL of methanol, and then disperse 5 g of the precursor in 50 mL of a mixed solution of 2-aminoterephthalic acid and methanol, and place in a high-pressure reactor for a second solvent thermal reaction at a reaction temperature of 120°C for 7 hours, then wash and filter to obtain a catalyst for synthesizing rigid polyurethane.

[0023] Comparative Example 2 This comparative example provides a method for preparing a catalyst for synthesizing rigid polyurethane, and the specific steps are as follows: S1: dissolving 4.85 g of bismuth nitrate pentahydrate in 50 mL of nitric acid solution having a concentration of 1 mol / L to form solution A; S2: Dissolve hydroxypropyl methylcellulose, isooctanoic acid, and polyvinyl pyrrolidone in ethylene glycol, wherein the ratio of bismuth nitrate pentahydrate, hydroxypropyl methylcellulose, isooctanoic acid, polyvinyl pyrrolidone, and ethylene glycol is 0.01 mol: 0.001 mol: 0.03 mol: 0.001 mol: 50 mL, and stir well to obtain solution B; S3: Slowly add solution A to solution B, stir and mix thoroughly, then place in a high-pressure reactor for solvent thermal reaction at a reaction temperature of 160° C. for 8 h, then wash and filter to obtain a catalyst for synthesizing rigid polyurethane.

[0024] Comparative Example 3 This comparative example provides a method for preparing a catalyst for synthesizing rigid polyurethane, and the specific steps are as follows: S1: dissolving 4.85 g of bismuth nitrate pentahydrate in 50 mL of nitric acid solution having a concentration of 1 mol / L to form solution A; S2: dissolving isooctanoic acid and polyvinyl pyrrolidone in ethylene glycol, wherein the ratio of bismuth nitrate pentahydrate, isooctanoic acid, polyvinyl pyrrolidone and ethylene glycol is 0.01 mol: 0.03 mol: 0.001 mol: 50 mL, and stirring well to obtain solution B; S3: Slowly add solution A to solution B, stir and mix thoroughly, then place in a high-pressure reactor for solvent thermal reaction at a reaction temperature of 160° C. for 8 h, then wash and filter to obtain a catalyst for synthesizing rigid polyurethane.

[0025] Performance Test: 2g of the catalyst prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were respectively mixed with 80g of polyether polyol, 2g of silicone oil, 1g of trimethyl phosphate, 2g of water, and 1g of cyclopentane in a stirring tank, and then 100g of xylene diisocyanate was added, and stirred at 25°C at a stirring speed of 2000r / min for 7s, and then poured into a mold coated with a release agent and foamed at 28°C for 5min, and then allowed to stand and cure at room temperature for 20min to obtain a hard polyurethane material. The reaction results are shown in Table 1: Table 1

[0026] The mechanical properties of the hard polyurethane materials prepared by the catalysts obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were tested, and the results are shown in Table 2: Table 2

Claims

1. A method for preparing a catalyst for synthesizing rigid polyurethane, characterized in that: The steps include: S1: dissolving a bismuth salt in a nitric acid solution to form a solution A; S2: dissolving hydroxypropyl methylcellulose, isooctanoic acid and polyvinyl pyrrolidone in ethylene glycol and stirring thoroughly to obtain solution B; S3: Slowly drop solution A into solution B, stir and mix thoroughly, then place in a high pressure reactor for a first solvothermal reaction to obtain a precursor; S4: dispersing the precursor in a mixed solution of 2-aminoterephthalic acid and methanol, placing the mixture in a high-pressure reactor for a second solvent thermal reaction, and then washing and filtering to obtain a catalyst for synthesizing rigid polyurethane.

2. The method for preparing a catalyst for synthesizing rigid polyurethane according to claim 1, characterized in that: In step S1, the bismuth salt is at least one of bismuth nitrate pentahydrate and bismuth acetate.

3. The method for preparing a catalyst for synthesizing rigid polyurethane according to claim 1, characterized in that: In step S1, the concentration of the nitric acid solution is 1-2 mol / L, and the addition ratio of the bismuth salt to the nitric acid solution is 0.01 mol:50-80 mL.

4. The method for preparing a catalyst for synthesizing rigid polyurethane according to claim 1, characterized in that: The ratio of bismuth salt, hydroxypropyl methylcellulose, isooctanoic acid, polyvinyl pyrrolidone and ethylene glycol is 0.01 mol: 0.001 mol: 0.03 mol: 0.001 mol: 50~80 mL.

5. The method for preparing a catalyst for synthesizing rigid polyurethane according to claim 1, characterized in that: In step S3, the first solvent thermal reaction temperature is 160-180° C., and the reaction time is 6-8 h.

6. The method for preparing a catalyst for synthesizing rigid polyurethane according to claim 1, characterized in that: In step S4, the addition ratio of 2-aminoterephthalic acid and methanol is 1-2 g: 30-50 mL.

7. The method for preparing a catalyst for synthesizing rigid polyurethane according to claim 1, characterized in that: In step S4, the addition ratio of the precursor to the mixed solution of 2-aminoterephthalic acid and methanol is 3-5 g:30-50 mL.

8. The method for preparing a catalyst for synthesizing rigid polyurethane according to claim 1, characterized in that: In step S4, the second solvent thermal reaction temperature is 120-130° C., and the reaction time is 6-8 h.

9. The method for preparing a catalyst for synthesizing rigid polyurethane according to claim 8, characterized in that: In step S4, the second solvent thermal reaction temperature is 120° C. and the reaction time is 7 h.

10. The catalyst for synthesizing rigid polyurethane prepared by the method for preparing the catalyst for synthesizing rigid polyurethane according to any one of claims 1 to 9.

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