Preparation method of polyurethane chain extender 2-methoxy-2'-aminobiphenyl

Abstract

The invention discloses a preparation method of polyurethane chain extender 2-methoxy-2'-aminobenzidine, which relates to the technical field of polyurethane chain extenders. The preparation method comprises the following steps: weighing o-chloroaniline and methanol in proportion; adding o-chloroaniline into a high-pressure reactor, adding methanol and a copper catalyst, heating, and keeping the reaction at a constant temperature; sampling and analyzing the reacted substances; and cooling the product after recovering methanol. The advantages of the invention are as follows: 2-methoxy-2'-aminobenzidine is directly synthesized from o-chloroaniline and methanol under the catalysis, the reaction steps are simple, the product is safe and non-toxic, the raw material cost for preparation is low, the preparation cost is reduced, and it is suitable for industrial production. The tensile strength of the polyurethane product chain-extended by 2-methoxy-2'-aminobenzidine is improved, the requirements for the tensile strength of polyurethane can be met, and the actual application range is wider.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane chain extenders, and particularly relates to a preparation method of a polyurethane chain extender 2-methoxy-2'-aminobenzidine. Background Art

[0002] A chain extender, also known as a chain growth agent, is a substance that can react with functional groups on the linear polymer chain to expand the molecular chain and increase the molecular weight. The chain extender is very important for the synthesis of polyurethane adhesives and sealants, directly affecting the mechanical properties and processing properties of the products, and is a necessary reagent in polyurethane production. Polyurethane is a prepolymer formed by the reaction of aliphatic and aromatic monomers containing diisocyanate groups with polyesters or polyethers containing diols or polyols. When in use, a chain extender is added to make the resin chain-extended and formed. Currently, 3,3′-dichloro-4,4-diaminodiphenylmethane is commonly used. It is an aromatic diamine chain extender and is an extremely important chain extender in the production of polyurethane, especially polyurethane rubber, coatings and other products. However, it has potential toxicity, and alternative chain extenders need to be sought.

[0003] Patent CN202110917970.8 discloses a lignin-based polyurethane chain extender and its preparation method and application. The disclosed carbamate-containing diol polyurethane chain extender is an environmentally friendly chain extender, which can replace the currently used 3,3′-dichloro-4,4-diaminodiphenylmethane chain extender. However, the tensile strength of the polyurethane product chain-extended by it is not high, and it is limited in actual application and cannot be applied to the production of polyurethanes with higher requirements for tensile strength. 2-methoxy-2'-aminobenzidine can meet the requirements of tensile strength, but there is no record in the prior art of applying 2-methoxy-2'-aminobenzidine to chain extenders. In addition, in the prior art, 2-methoxy-2'-aminobenzidine is obtained by reacting 2-nitrofluorobenzene with o-methoxyaniline and then hydrogenating. However, due to the high cost of fluorine-containing compounds, it is not suitable for industrial production. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a preparation method of a polyurethane chain extender 2-methoxy-2'-aminobenzidine, which can solve the problems in the prior art that the tensile strength of the polyurethane product chain-extended by the polyurethane chain extender is not high, is limited in actual application, the existing synthesis method needs to use fluorine-containing compounds, and the fluorine-containing compounds have high costs and are not suitable for industrial production.

[0005] To solve the above technical problems, the technical solution of the present invention is as follows: including the following steps:

[0006] S1. Weigh o-chloroaniline and methanol in proportion;

[0007] S2. Add o-chloroaniline into a high-pressure reaction kettle, and add methanol and a copper catalyst, heat, and keep the reaction at a constant temperature;

[0008] S3. Sample and analyze the reacted substances;

[0009] S4. Recover methanol and then cool to obtain the product;

[0010] The reaction process of the above steps is as follows:

[0011]

[0012] Further, in the step S1, the ratio of the weighed amounts of o-chloroaniline and methanol is 1:1 - 3.

[0013] Further, in the step S2, the ratio of the amount of the copper catalyst used to methanol is 1:5 - 20.

[0014] Further, in the step S2, heat to 250 - 350 °C and keep the temperature for 10 hours.

[0015] Further, in the step S3, sample and analyze the reacted substances, and analyze by HPLC to determine that the o-chloroaniline reaction is complete.

[0016] Further, in the step S4, cool to room temperature.

[0017] The advantages of the present invention are as follows: 2-Methoxy-2'-aminobenzidine is directly synthesized from o-chloroaniline and methanol under the catalysis. The reaction steps are simple, the product is safe and non-toxic, the raw material cost for preparation is relatively low, the preparation cost is reduced, it is suitable for industrial production. The tensile strength of the polyurethane product chain-extended with 2-methoxy-2'-aminobenzidine as a chain extender is improved, which can meet the requirements of the tensile strength of polyurethane, and the actual application range is wider. Specific Embodiments

[0018] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further details the present invention in combination with specific embodiments. The following embodiments can enable those skilled in the art to more comprehensively understand the present invention, but do not limit the present invention within the scope of the described embodiments.

[0019] The present specific embodiment adopts the following technical solutions: including the following steps:

[0020] S1. Weigh o-chloroaniline and methanol in proportion, and the ratio of the weighed amounts of o-chloroaniline and methanol is 1:1 - 3.

[0021] S2. Add o-chloroaniline into a high-pressure reactor, and add methanol and a copper catalyst, heat to 300 °C, keep the temperature for 10 hours for reaction, and the ratio of the amount of the copper catalyst used to methanol is 1:5 - 20.

[0022] S3. Take a sample of the reacted substances for analysis. By HPLC analysis, it is found that the o-chloroaniline reaction is complete.

[0023] S4. After recovering methanol, cool to obtain the product, and cool to room temperature.

[0024] The reaction process of the above steps is as follows:

[0025]

[0026] Example 1:

[0027] S1. Weigh 100 g of o-chloroaniline and 150 g of methanol.

[0028] S2. Add o-chloroaniline to a high-pressure reactor, and add methanol and 10 g of copper catalyst. Heat to 300 °C and hold for 10 hours for reaction.

[0029] S3. Take a sample of the reacted substances for analysis. By HPLC analysis, it is found that the o-chloroaniline reaction is complete.

[0030] S4. After recovering methanol, cool to obtain the product, cool to room temperature, and the yield is 65%.

[0031] Example 2:

[0032] This example has the same steps as Example 1, except that the addition amount of the copper catalyst is 20 g and the yield is 66%.

[0033] Using the same prepolymer, 2-methoxy-2'-aminobiphenylamine and MOCA prepared through Example 1 and Example 2 are respectively used for chain extension, and curing and molding are carried out at a certain temperature. The curing and molding method of the prepolymer is a conventional method, only replacing the chain extender. The obtained elastomers are respectively subjected to mechanical experiments, and the mechanical properties are compared. The results are shown in Table 1.

[0034] Table 1: Comparison table of mechanical properties of elastomers obtained by chain extension with 2-methoxy-2'-aminobiphenylamine and MOCA prepared through Example 1 and Example 2

[0035]

[0036]

[0037] As can be seen from Table 1, the 2-methoxy-2'-aminobenzidine prepared in Examples 1 and 2 can replace 3,3'-dichloro-4,4-diaminodiphenylmethane as a polyurethane chain extender. Compared with the elastomer chain-extended with 3,3'-dichloro-4,4-diaminodiphenylmethane as the chain extender, the elongation rate of the elastomer chain-extended with the 2-methoxy-2'-aminobenzidine chain extender is significantly improved on the basis of maintaining the original mechanical properties; the tensile strength of the elastomer chain-extended with the existing lignin-based polyurethane chain extender is 11-14 MP. Compared with the elastomer chain-extended with the existing lignin-based polyurethane chain extender, the tensile strength of the elastomer chain-extended with the 2-methoxy-2'-aminobenzidine chain extender is significantly improved, and it can meet the requirements of the polyurethane tensile strength on the basis of safety and non-toxicity; in the examples, 2-methoxy-2'-aminobenzidine is directly synthesized from o-chloroaniline and methanol under the catalysis, the reaction steps are simple, the raw material cost for preparation is low, the preparation cost is reduced, and it is suitable for industrial production.

[0038] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. Preparation method of polyurethane chain extender 2-methoxy-2'-aminobiphenyl Characterized in that: Comprising the following steps: S1. Weigh o-chloroaniline and methanol in proportion; S2. Add o-chloroaniline to a high-pressure reactor, add methanol and a copper catalyst, heat, and keep the reaction at a constant temperature; S3. Take a sample of the reacted substance for analysis; S4. Recover methanol and then cool to obtain the product; The reaction process of the above steps is as follows:

2. The preparation method of polyurethane chain extender 2-methoxy-2'-aminobiphenyl according to claim 1, Characterized in that: In the step S1, the ratio of the weighed amounts of o-chloroaniline and methanol is 1:1 - 3.

3. The preparation method of polyurethane chain extender 2-methoxy-2'-aminobiphenyl according to claim 1, Characterized in that: In the step S2, the ratio of the amount of the copper catalyst to methanol is 1:5 - 20.

4. The preparation method of polyurethane chain extender 2-methoxy-2'-aminobiphenyl according to claim 1, Characterized in that: In the step S2, heat to 250 - 350 °C and keep the temperature for 10 hours.

5. The preparation method of polyurethane chain extender 2-methoxy-2'-aminobiphenyl according to claim 1, Characterized in that: In the step S3, take a sample of the reacted substance for analysis, and analyze by HPLC to determine that the o-chloroaniline reaction is complete.

6. The preparation method of polyurethane chain extender 2-methoxy-2'-aminobiphenyl according to claim 1, Characterized in that: In the step S4, cool to room temperature.

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