Method for adjusting viscosity of dicyclopentadiene monomer

Abstract

The invention provides a method for adjusting the viscosity of a dicyclopentadiene monomer. By adopting the method disclosed by the invention, no additive is contained, the process is simple, the viscosity of the dicyclopentadiene monomer at room temperature can be adjusted between 100 mPa.s and 5000 mPa.s, and the requirements of various composite material forming processes on the resin viscosity are met. The problem that an existing dicyclopentadiene monomer is too low in viscosity is solved, and the dicyclopentadiene monomer can be suitable for preparing a carbon fiber composite material.

Description

Technical Field

[0001] The invention belongs to the field of resin material preparation, and particularly relates to a method for adjusting the viscosity of dicyclopentadiene monomer. Background Art

[0002] Polydicyclopentadiene (PDCPD) is a new type of thermosetting resin with both rigidity and toughness. It is obtained by ring-opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) catalyzed by organic metals. Since the viscosity of DCPD monomer is relatively low (less than 10mPa·s at room temperature), once the reaction is initiated after adding the catalyst, the polymerization can be completed in a very short time (3-5min). At present, it has been prepared through reaction injection molding (RIM) for a variety of applications in automobile shells and other large-scale engineering equipment outer shells, and the industry development has become increasingly mature.

[0003] With the rapid development of new materials, a single material cannot meet the diverse application scenarios. Compounding PDCPD materials with continuous reinforced carbon fibers through a low-cost molding process to prepare high-impact composite materials will be a research direction with commercial prospects and scientific significance.

[0004] Since the viscosity of DCPD monomer is low, less than 10mPa·s at room temperature, and has certain volatility, it is not currently suitable for any long fiber reinforced composite material preparation process. In order to increase the viscosity of DCPD monomer, the existing technology adds soluble polymer plastics to it, but it will lead to a decrease in the mechanical properties and heat resistance of the product after DCPD polymerization. How to solve the viscosity problem of DCPD monomer is a prerequisite for the subsequent preparation of carbon fiber reinforced polydicyclopentadiene composite materials. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a method for increasing the viscosity of a DCPD monomer. The method has a simple preparation process, strong operability, and is suitable for industrial production. The viscosity after modification can be adjusted between 100 and 5000 mPa·s, meeting the resin viscosity requirements of various composite material molding processes.

[0006] The present invention provides a method for adjusting the viscosity of dicyclopentadiene monomer, comprising the following steps:

[0007] S1: dissolving the Grubbs II catalyst in cyclohexylbenzene at elevated temperature, and then adding tributyl phosphite as a retarder to prepare a catalyst solution;

[0008] S2: adding the catalyst solution obtained in step S1 to the dicyclopentadiene monomer raw material, heating and prepolymerizing to obtain a dicyclopentadiene monomer product; wherein the molar ratio of the Grubbs second-generation catalyst to the dicyclopentadiene monomer raw material is 1:(20000-100000); if the amount of the Grubbs second-generation catalyst is too small, DCPD will not be prepolymerized; if the amount of the Grubbs catalyst is too large, DCPD will directly cross-link, and the product is an insoluble gel or solid.

[0009] Preferably, in step S1, the mass ratio of Grubbs second-generation catalyst to cyclohexylbenzene is 1:(100-400); the dissolution temperature of Grubbs second-generation catalyst in cyclohexylbenzene is 40-60°C, and the dissolution time is 30-60 minutes; the molar ratio of Grubbs second-generation catalyst to tributyl phosphite is 1:(1-8).

[0010] Preferably, in step S2, the dicyclopentadiene monomer raw material is a mixture of dicyclopentadiene and norbornene, and the mass fraction of norbornene is 3% to 5%; the prepolymerization temperature is 60 to 90° C., and the prepolymerization time is 15 to 30 minutes.

[0011] By adopting the above method for adjusting the viscosity of dicyclopentadiene monomer, the viscosity of the obtained dicyclopentadiene monomer product is 100 to 5000 mPa·s. The viscosity can be adjusted by the following means: for example, for the prepolymerized DCPD product, if the viscosity is too high, then the DCPD monomer is re-added to the prepolymer of this viscosity. This prepolymer can be re-dissolved in the DCPD monomer, which is equivalent to a viscosity reduction process, thereby achieving adjustable viscosity.

[0012] The beneficial effects of the present invention are as follows: (1) The present invention mainly solves the problem that the viscosity of the existing dicyclopentadiene monomer is too low, which limits its application in carbon fiber composite materials. (2) By adopting the method provided by the present invention, it is not necessary to add any additives to the DCPD monomer, and it is only necessary to adjust the content of the Grubbs catalyst so that it only polymerizes without cross-linking, thereby achieving the purpose of adjusting the viscosity of the DCPD monomer. (3) By adopting the method provided by the present invention, no additives are contained, the process is simple, and the viscosity of the dicyclopentadiene monomer can be adjusted between 100 and 5000 mPa·s at room temperature, meeting the resin viscosity requirements of various composite material molding processes. DETAILED DESCRIPTION

[0013] The present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments are only used to illustrate the invention, but do not limit the scope of the present invention in any form. In addition, it should be noted that those skilled in the art can make various modifications and improvements to the present invention. These all belong to the protection scope of the present invention.

[0014] Example 1

[0015] (1) Grubbs second-generation catalyst and cyclohexylbenzene were prepared in a mass ratio of 1:100, and the temperature was raised to 60°C. After 1 hour, the catalyst was completely dissolved, and then a retarder was added in a molar ratio of catalyst to tributyl phosphite of 1:1. The catalyst solution was left at room temperature for use.

[0016] (2) A prepolymerization formula with a molar ratio of catalyst to DCPD monomer of 1:20,000 was used, the amount of catalyst solution was calculated based on the catalyst concentration in (1), and added to the dicyclopentadiene monomer (norbornene content was 5%), and the prepolymerization process was completed after the temperature was raised to 60° C. for half an hour.

[0017] Example 2

[0018] (1) Grubbs second-generation catalyst and cyclohexylbenzene were prepared in a mass ratio of 1:200, and the temperature was raised to 45° C. After 45 minutes, the catalyst was completely dissolved, and then a retarder was added in a molar ratio of catalyst to tributyl phosphite of 1:2. The catalyst solution was placed at room temperature for use.

[0019] (2) A prepolymerization formula with a molar ratio of catalyst to DCPD monomer of 1:30,000 was used, the amount of catalyst solution was calculated based on the catalyst concentration in (1), added to the dicyclopentadiene monomer (norbornene content was 3%), the temperature was raised to 60° C., and the prepolymerization process was completed after half an hour.

[0020] Example 3

[0021] (1) Grubbs second-generation catalyst and cyclohexylbenzene were prepared in a mass ratio of 1:400, and the temperature was raised to 45° C. After 45 minutes, the catalyst was completely dissolved, and then a retarder was added in a molar ratio of catalyst to tributyl phosphite of 1:4. The catalyst solution was placed at room temperature for use.

[0022] (2) A prepolymerization formula with a molar ratio of catalyst to DCPD monomer of 1:100,000 was used, the amount of catalyst solution was calculated based on the catalyst concentration in (1), added to the dicyclopentadiene monomer (norbornene content was 5%), the temperature was raised to 90° C., and the prepolymerization process was completed after 15 minutes.

[0023] Example 4

[0024] (1) Grubbs second-generation catalyst and cyclohexylbenzene were prepared in a mass ratio of 1:300, and the temperature was raised to 45° C. After half an hour, the catalyst was completely dissolved, and then a retarder was added in a molar ratio of catalyst to tributyl phosphite of 1:8. The catalyst solution was placed at room temperature for use.

[0025] (2) A prepolymerization formula with a molar ratio of catalyst to DCPD monomer of 1:40,000 was used. The amount of catalyst solution was calculated based on the catalyst concentration in (1), added to the dicyclopentadiene monomer (norbornene content was 5%), and the prepolymerization process was completed after the temperature was raised to 75° C. for half an hour.

[0026] Example 5

[0027] (1) Grubbs second-generation catalyst and cyclohexylbenzene were prepared in a mass ratio of 1:200, and the temperature was raised to 40°C. After half an hour, the catalyst was completely dissolved, and then a retarder was added in a molar ratio of catalyst to tributyl phosphite of 1:4. The catalyst solution was left at room temperature for use.

[0028] (2) A prepolymerization formula with a molar ratio of catalyst to DCPD monomer of 1:50,000 was used, the amount of catalyst solution was calculated based on the catalyst concentration in (1), added to the dicyclopentadiene monomer (norbornene content was 4%), the temperature was raised to 75° C., and the prepolymerization process was completed after 20 minutes.

[0029] Comparative Example 1

[0030] (1) Grubbs second-generation catalyst and cyclohexylbenzene were prepared in a mass ratio of 1:100, and the temperature was raised to 60°C. After 1 hour, the catalyst was completely dissolved, and then a retarder was added in a molar ratio of catalyst to tributyl phosphite of 1:2. The catalyst solution was left at room temperature for use.

[0031] (2) A catalyst to DCPD monomer molar ratio of 1:10000 was used as the prepolymerization formula, the amount of catalyst solution was calculated based on the catalyst concentration in (1), and added to the dicyclopentadiene monomer (norbornene content was 5%), and the temperature was raised to 60° C. for half an hour.

[0032] Comparative Example 2

[0033] (1) Grubbs second-generation catalyst and cyclohexylbenzene were prepared in a mass ratio of 1:100, and the temperature was raised to 60°C. After 1 hour, the catalyst was completely dissolved, and then a retarder was added in a molar ratio of catalyst to tributyl phosphite of 1:2. The catalyst solution was left at room temperature for use.

[0034] (2) A catalyst to DCPD monomer molar ratio of 1:120000 was used as the prepolymerization formula, the amount of catalyst solution was calculated based on the catalyst concentration in (1), and added to the dicyclopentadiene monomer (norbornene content was 5%), and the temperature was raised to 60° C. for half an hour.

[0035] Table 1 Example DCPD rotational viscosity

[0036] Serial number Viscosity (mPa·s), room temperature Example 1 3800～4200 Example 2 1600～1900 Example 3 1600～1900 Example 4 500～800 Example 5 100～300 Comparative Example 1 Gel, no obvious fluidity Comparative Example 2 ＜10

[0037] From the above experimental results: at a specific molar ratio of DCPD to Grubbs second-generation catalyst (1:20000 to 1:100000), DCPD only undergoes linear polymerization without crosslinking. This is because the two structures present in the molecular formula of dicyclopentadiene: norbornene and cyclopentene have different reactivity. Among them, the ring tension of norbornene is much greater than that of cyclopentene, so the norbornene ring preferentially undergoes a ring-opening reaction. In other words, when the catalyst content is insufficient, cyclopentene in the system may not or less participate in the crosslinking reaction (as shown in Comparative Example 1). Secondly, the higher the catalyst content, the higher the viscosity of the prepolymer product (as shown in Example 2). Catalyst content is the most important factor affecting the viscosity of the prepolymer.

[0038] In addition, in Example 1, a certain proportion of DCPD monomer can be added to the prepolymer again, and the linear prepolymer can be redissolved in the DCPD monomer. According to this method, a wide range of viscosity adjustment can be achieved.

[0039] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not limit it. Although this patent is described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions recorded in the aforementioned embodiments or to replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims

1. A method for adjusting the viscosity of dicyclopentadiene monomer, characterized in that: The following steps are involved: S1: dissolving the Grubbs II catalyst in cyclohexylbenzene at elevated temperature, and then adding tributyl phosphite as a retarder to prepare a catalyst solution; S2: adding the catalyst solution obtained in step S1 to the dicyclopentadiene monomer raw material, heating and prepolymerizing to obtain a dicyclopentadiene monomer product; wherein the molar ratio of the Grubbs second-generation catalyst to the dicyclopentadiene monomer raw material is 1:(20000-100000).

2. A method for regulating the viscosity of dicyclopentadiene monomer as claimed in claim 1, characterized in that: In step S1, the mass ratio of the Grubbs second-generation catalyst to cyclohexylbenzene is 1:(100-400).

3. A method for regulating the viscosity of dicyclopentadiene monomer as claimed in claim 1, characterized in that: In step S1, the dissolution temperature of the Grubbs second-generation catalyst in cyclohexylbenzene is 40-60° C., and the dissolution time is 30-60 minutes.

4. A method for regulating the viscosity of dicyclopentadiene monomer as claimed in claim 1, characterized in that: In step S1, the molar ratio of the Grubbs second generation catalyst to tributyl phosphite is 1:(1-8).

5. A method for regulating the viscosity of dicyclopentadiene monomer as claimed in claim 1, characterized in that: In step S2, the dicyclopentadiene monomer raw material is a mixture of dicyclopentadiene and norbornene, and the mass fraction of norbornene is 3% to 5%.

6. A method for adjusting the viscosity of dicyclopentadiene monomer as claimed in claim 1, characterized in that: In step S2, the prepolymerization temperature is 60-90° C., and the prepolymerization time is 15-30 minutes.

7. A method for adjusting the viscosity of dicyclopentadiene monomer as claimed in claim 1, characterized in that: The viscosity of the obtained dicyclopentadiene monomer product is 100 to 5000 mPa·s.