Preparation of high activity and high stability chdi-based elastomers by prepolymerization

Abstract

This invention belongs to the field of polyurethane elastomers and provides a prepolymerization method for preparing highly active and stable CHDI-based elastomers. The purpose is to solve the problems of low reactivity of existing CHDI, the need to add more catalysts to regulate the reaction rate, which leads to unstable product performance. The invention proposes to introduce PPDI monomers into the synthesis process of CHDI-based prepolymers. By utilizing the high reactivity of PPDI and its structural similarity to CHDI, high efficiency of prepolymerization is ensured without the need for catalyst introduction. The high activity of chain extension reaction is also beneficial to the stability of subsequent elastomer performance.

Description

Technical Field

[0001] This invention belongs to the field of 1,4-cyclohexane diisocyanate (CHDI) based polyurethane elastomers, and relates to a prepolymer method for preparing highly active and stable CHDI based elastomers. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] 1,4-Cyclohexane diisocyanate (CHDI) has two isomers, cis and trans. The trans structure is superior to the cis structure in terms of performance and activity. However, an excessively high trans ratio can cause difficulties in subsequent plasticizing processes. Therefore, in practical applications, it is usually necessary to use a combination of cis and trans isomers and add more catalysts to meet the molding and processing requirements. For example, patents CN104017166B, CN106810671B, and CN118812814A all introduce a large amount of catalysts during the reaction process. However, the addition of excessive catalysts will have a continuous catalytic effect on the material during processing and application at high temperatures, affecting the stability of the final product performance. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a prepolymerization method for preparing highly active and stable CHDI-based elastomers. By introducing terephthalic diisocyanate (PPDI) monomers during the prepolymerization process, and utilizing the high initiation activity of PPDI and its structural similarity to CHDI, this method ensures high efficiency in prepolymerization and high activity in the chain extension reaction without the need for a catalyst, while also contributing to the stability of the subsequent elastomer properties.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a prepolymer method for preparing a highly active and stable CHDI-based elastomer, comprising: Under an inert atmosphere, the dehydrated oligomeric polyol is reacted with CHDI monomer. After a predetermined reaction time, PPDI monomer is added to continue the reaction until NCO reaches the theoretical value, thus obtaining a prepolymer with CHDI as the main structure. A chain extender is added to the prepolymer with CHDI as the main structure to carry out the reaction. After the reaction is completed, the prepolymer is degassed, poured into a mold, and cured to obtain the final product.

[0006] In a second aspect, the present invention provides a CHDI-based elastomer prepared by the above-described method.

[0007] A third aspect of the present invention provides applications of the above-described CHDI-based elastomer in the fields of medical, automotive, mining, aerospace, and industrial installations.

[0008] Beneficial effects of the present invention (1) This invention introduces PPDI into CHDI-based elastomers prepared by prepolymerization. PPDI has high activity and high exothermic reaction, which improves the disadvantages of long reaction time, low reaction efficiency or the need to add more catalysts during the polymerization of CHDI prepolymers.

[0009] (2) The present invention introduces PPDI into CHDI-based elastomers prepared by prepolymerization, which can effectively avoid the addition of excessive catalyst in the subsequent chain extension process of CHDI prepolymer and improve the stability of CHDI-based elastomers.

[0010] (3) The present invention introduces PPDI with a similar structure on the basis of prepolymerization method to prepare CHDI-based elastomer, which improves the activity of prepolymerization reaction without affecting the high heat resistance, low internal heat generation and excellent comprehensive performance of CHDI-based prepolymer in subsequent preparation of elastomer or other applications.

[0011] (4) The preparation method of the present invention is simple, practical and easy to promote. Detailed Implementation

[0012] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0013] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods in the art or product instructions. Similarly, unless otherwise specified, the test methods of this invention are performed in accordance with conventional methods in the art or industry-standard methods or practices. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0014] Due to the low reactivity of CHDI, a large amount of catalyst is often required to improve reaction efficiency during prepolymerization or subsequent chain extension processing. However, the addition of catalyst may introduce instability into the regulation of reaction performance, and excessive catalyst can easily lead to continuous catalytic reaction during subsequent high-temperature processing, causing uncertainty in product performance. Therefore, this invention provides a prepolymerization method for preparing highly active and stable CHDI-based elastomers, comprising: Under an inert atmosphere, the dehydrated oligomeric polyol is reacted with CHDI monomer. After a predetermined reaction time, PPDI monomer is added to continue the reaction until NCO reaches the theoretical value, thus obtaining a prepolymer with CHDI as the main structure. A chain extender is added to the prepolymer with CHDI as the main structure to carry out the reaction. After the reaction is completed, the prepolymer is degassed, poured into a mold, and cured to obtain the final product.

[0015] Oligomeric polyols mainly function as soft segment components in polyurethanes. They react with isocyanates and other compounds to form urethane structures, directly affecting the physical properties and microstructure of polyurethanes. Therefore, this invention has investigated the types of oligomeric polyols. In some embodiments, the oligomeric polyol is selected from at least one of polytetramethylene ether polyol, polycaprolactone polyol, polycarbonate polyol, polyadipate polyol, polyether ester copolymer polyol, polyethylene glycol, and polypropylene glycol to obtain superior product performance and high-temperature stability.

[0016] The trans structure is superior to the cis structure in terms of performance and activity, but an excessively high trans ratio can cause difficulties in subsequent plasticizing processes. Therefore, in practical applications, it is usually necessary to use a combination of cis and trans ratios. To this end, this invention has studied the cis-trans ratio of CHDI. In some embodiments, the cis-trans ratio of CHDI is 2 / 8 to 8 / 2 to obtain better high-temperature stability while facilitating plasticizing processes.

[0017] The timing of PPDI addition affects the product's performance and high-temperature stability. Therefore, this invention has studied the timing of PPDI addition. In some embodiments, the predetermined time is 15-30 minutes after the reaction temperature reaches its maximum, so as to prepare a high-performance CHDI-based elastomer without adding a catalyst.

[0018] This invention introduces structurally similar PPDI into the prepolymerization process for preparing CHDI-based elastomers to improve prepolymerization reactivity. To this end, the total amount and ratio of CHDI and PPDI were investigated. In some embodiments, the mass ratio of the total CHDI and PPDI to the oligomeric polyol is 1:5 to 1:10. In other embodiments, the mass / molar ratio of PPDI to CHDI is 1:5 to 1:10 to prepare CHDI-based elastomers with superior performance.

[0019] Chain extenders primarily function in the synthesis of polyurethane elastomers to increase molecular chain length and crosslinking density, thereby improving the strength and elasticity of the elastomer. Therefore, this invention has investigated the types of chain extenders. In some embodiments, the chain extender is selected from at least one of ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, trimethylolpropane, hydroquinone dihydroxyethyl ether, and 3,3-dichloro-4,4-diaminodiphenylmethane to improve chain extension efficiency.

[0020] The curing temperature affects the final properties of polyurethane. Therefore, the present invention has studied the curing temperature. In some embodiments, the curing temperature is 110-130°C to obtain polyurethane with better performance.

[0021] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0022] Example 1 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2h. Then, the temperature was lowered to 80℃ and 302g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection. After the reaction temperature reached its maximum, 32g of PPDI was added within 25min to continue the reaction until NCO reached 6.4%, thus obtaining a prepolymer with CHDI as the main structure. Then, butanediol was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain a CHDI-based elastomer.

[0023] Example 2 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2h. Then, the temperature was lowered to 80℃ and 268g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection. After the reaction temperature reached its maximum, 65g of PPDI was added within 20min to continue the reaction until NCO reached 6.5%, thus obtaining a prepolymer with CHDI as the main structure. Then, butanediol was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain a CHDI-based elastomer.

[0024] Example 3 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2h. Then, the temperature was lowered to 80℃ and 302g of CHDI with a cis / trans ratio of 4 / 6 was added under nitrogen protection. After the reaction temperature reached its maximum, 32g of PPDI was added within 25min to continue the reaction until NCO reached 6.4%, thus obtaining a prepolymer with CHDI as the main structure. Then, butanediol was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain a CHDI-based elastomer.

[0025] Example 4 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2h. Then, the temperature was lowered to 80℃ and 302g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection. After the reaction temperature reached its maximum, 32g of PPDI was added within 25min to continue the reaction until NCO reached 6.4%, thus obtaining a prepolymer with CHDI as the main structure. Then, hydroquinone dihydroxyethyl ether was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain a CHDI-based elastomer.

[0026] Example 5 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2h. Then, the temperature was lowered to 80℃ and 302g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection. After the reaction temperature reached its maximum, 32g of PPDI was added within 25min to continue the reaction until NCO reached 6.4%, thus obtaining a prepolymer with CHDI as the main structure. Then, 3,3-dichloro-4,4-diaminodiphenylmethane was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 110℃ to obtain a CHDI-based elastomer.

[0027] Example 6 First, 1000g of polycaprolactone polyol with a molecular weight of 2000 g / mol was vacuum dehydrated at 120℃ for 2h. Then, the temperature was lowered to 80℃ and 153g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection. After the reaction temperature reached its maximum, 16g of PPDI was added within 30min to continue the reaction until NCO reached 3.8%, thus obtaining a prepolymer with CHDI as the main structure. Then, butanediol was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 110℃ to obtain a CHDI-based elastomer.

[0028] Example 7 First, 1000g of polybutylene adipate polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 120℃ for 2 hours. Then, the temperature was lowered to 80℃ and 302g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection. After the reaction temperature reached its maximum, 32g of PPDI was added within 25 minutes to continue the reaction until NCO reached 6.4%, thus obtaining a prepolymer with CHDI as the main structure. Then, butanediol was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain a CHDI-based elastomer.

[0029] Comparative Example 1 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2 hours. Then, the temperature was lowered to 80℃ and 336g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection to react until NCO reached 6.4% to obtain CHDI prepolymer. Then, butanediol was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain CHDI-based elastomer.

[0030] Comparative Example 2 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2 hours. Then, the temperature was lowered to 80℃ and 336g of CHDI with a cis / trans ratio of 6 / 4 and 100ppm of stannous octoate were added under nitrogen protection to react until NCO reached 6.4% to obtain CHDI prepolymer. Then, butanediol was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain CHDI-based elastomer.

[0031] Comparative Example 3 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2 hours. Then, the temperature was lowered to 80℃ and 336g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection to react until NCO reached 6.4% to obtain CHDI prepolymer. Then, butanediol and 400ppm stannous octoate were added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain CHDI-based elastomer.

[0032] Comparative Example 4 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2h. Then, the temperature was lowered to 80℃ and 302g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection. After the reaction temperature reached its maximum, 35g of toluene diisocyanate (TDI) was added within 25min to continue the reaction until NCO reached 6.4%, thus obtaining a prepolymer with CHDI as the main structure. Then, butanediol was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain a CHDI-based elastomer.

[0033] Comparative Example 5 First, 1000g of polycaprolactone polyol with a molecular weight of 1000 g / mol was vacuum dehydrated at 110℃ for 2h. Then, the temperature was lowered to 80℃ and 302g of CHDI with a cis / trans ratio of 6 / 4 was added under nitrogen protection. After the reaction temperature reached its maximum, 42g of 1,5-naphthalene diisocyanate (NDI) was added within 25min to continue the reaction until NCO reached 6.4%, thus obtaining a prepolymer with CHDI as the main structure. Then, butanediol was added to the prepolymer for chain extension. After vacuum degassing, it was poured into a mold and cured at 120℃ to obtain a CHDI-based elastomer.

[0034] Table 1 shows a comparison of the prepolymerization time, gelation time during chain extension, elastomer tensile strength, and thermal decomposition temperature at 5% weight loss in the above embodiments and comparative examples. Table 1 Synthesis conditions and performance test results of various elastomers

[0035] As shown in Table 1, the CHDI-based elastomers with added PPDI in the examples exhibit significantly shorter prepolymerization and chain extension gelation times compared to the pure CHDI elastomer in Comparative Example 1, indicating that the addition of highly active PPDI can significantly improve polymerization efficiency. In Comparative Examples 2 and 3, the CHDI elastomers with added catalysts showed a significant improvement in polymerization efficiency; however, the thermal decomposition temperature of the elastomers decreased significantly due to the increased amount of catalyst added. This resulted in poor performance of the CHDI elastomers during processing or application at high temperatures due to the breakage of some chemical bonds. In Comparative Examples 4 and 5, TDI and NDI were used instead of PPDI. TDI, due to its lower activity than PPDI, had limited impact on the overall prepolymerization process due to its exothermic reaction, and the polymerization efficiency was not significantly improved. Although NDI had higher reactivity, its high melting point resulted in lower reaction efficiency with polyols during prepolymerization, requiring a longer prepolymerization time. Furthermore, the significant structural differences between TDI and NDI and CHDI made their chain segment regularity easily disrupted, affecting the microphase separation of the elastomer and leading to reduced strength. Therefore, introducing highly active PPDI into the CHDI prepolymerization process can improve polymerization efficiency without the need for a catalyst. Furthermore, the high rigidity of the benzene ring structure of PPDI, which is similar to that of CHDI, can further improve the elastomer strength and decomposition temperature, ensuring the high strength and high temperature stability of the CHDI-based elastomer.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high activity, high stability CHDI-based elastomer prepared by a prepolymerization process, characterized in that, Preparation methods include: Under an inert atmosphere, the dehydrated oligomeric polyol is reacted with CHDI monomer. After a predetermined reaction time, PPDI monomer is added to continue the reaction until NCO reaches the theoretical value, thus obtaining a prepolymer with CHDI as the main structure. A chain extender is added to the prepolymer with CHDI as the main structure to carry out the reaction. After the reaction is completed, the prepolymer is degassed, poured into a mold, and cured to obtain the final product.

2. The high activity, high stability CHDI-based elastomer prepared by the prepolymer method of claim 1, wherein, The oligomeric polyol is selected from at least one of polytetramethylene ether polyol, polycaprolactone polyol, polycarbonate polyol, polyadipate polyol, polyether ester copolyol, polyethylene glycol, and polypropylene glycol.

3. The highly active and stable CHDI-based elastomer prepared by the prepolymerization method as described in claim 1, characterized in that, The cis-trans ratio of the CHDI is 2 / 8 to 8 / 2.

4. The highly active and stable CHDI-based elastomer prepared by the prepolymerization method as described in claim 1, characterized in that, The predetermined time is 15-30 minutes after the reaction temperature reaches its maximum.

5. The highly active and stable CHDI-based elastomer prepared by the prepolymerization method as described in claim 1, characterized in that, The total mass ratio of CHDI and PPDI to the oligomeric polyol is 1:5 to 1:

10.

6. The highly active and stable CHDI-based elastomer prepared by the prepolymerization method as described in claim 1, characterized in that, The mass ratio of PPDI to CHDI is 1:5 to 1:

10.

7. The highly active and stable CHDI-based elastomer prepared by the prepolymerization method as described in claim 1, characterized in that, The chain extender is selected from at least one of ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, trimethylolpropane, hydroquinone dihydroxyethyl ether, and 3,3-dichloro-4,4-diaminodiphenylmethane.

8. The highly active and stable CHDI-based elastomer prepared by the prepolymerization method as described in claim 1, characterized in that, The ripening temperature is 110-130℃.

9. The application of the CHDI-based elastomer according to any one of claims 1-8 in the fields of medical, automotive, mining, aerospace, and industrial installations.

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