Preparation method of cardanol modified thermosetting phenolic resin

Abstract

In order to improve the toughness of the phenolic resin, the invention provides a toughening method of the phenolic resin, because cardanol contains a plurality of hydroxyl groups and a long carbon chain structure and can participate in a cross-linking reaction of a phenolic resin system in multiple dimensions, the cross-linking structure of the system is changed, and the toughness of the phenolic resin is improved. The comprehensive mechanical property of the system is effectively improved, and the material toughness can be greatly improved. The toughened resin can be applied to the industries of laminated boards, copper-clad plates and the like. The synthesis method comprises the following specific synthesis steps: 1, adding phenol, cardanol and a catalyst into a reaction kettle, heating to 70-90 DEG C, reacting, and adding a terminator after detecting that the content of cardanol is less than 1%; and 2, cooling the reaction kettle to 50-60 DEG C, adding phenol, formaldehyde and a basic catalyst, starting stirring, heating to 70-95 DEG C, carrying out a thermal reaction until free aldehyde is less than 1%, carrying out vacuum dehydration until the viscosity is qualified, and adding a solvent to adjust the solid content so as to obtain the cardanol modified thermosetting phenolic resin.

Description

Technical Field

[0001] This invention relates to a method for preparing phenolic resins, belonging to the field of polymer chemistry, specifically a method for preparing cashew phenol-modified thermosetting phenolic resins. Background Technology

[0002] Phenolic resin generally refers to a polymer material formed by dehydration condensation of phenol and formaldehyde solutions under heated acidic or alkaline conditions. With the continuous development of industrial technology, the requirements for the performance of composite materials are becoming increasingly stringent. However, the high brittleness of pure phenolic resin cured products has consistently limited its applications in many fields. Therefore, toughening and modifying phenolic resins to improve their mechanical properties remains a hot research topic for scholars both domestically and internationally, and will determine the future development direction of phenolic resins.

[0003] Phenolic resins are brittle, have low elongation, and their phenolic hydroxyl and methylene groups are easily oxidized. To meet the performance requirements of phenolic resins in copper-clad laminates, aerospace, and other high-end applications, toughening and heat-resistant modifications are necessary. Among existing modified phenolic resins, biomass toughening has become a mainstream toughening method.

[0004] The rapid development of information technology and electronic products has placed higher technical performance requirements on copper-clad laminates (CCLs). Various CCLs based on high-performance resins have been developed (such as MPPO, PTFE, CE, BMI, PMR, PCH, etc.), but they still cannot fully meet the requirements (cost, performance, process, etc.). Therefore, people are exploring the development of various high-performance resin matrices based on neophenolic resins.

[0005] Resin matrices, as high-performance materials, need to solve two major technical challenges in practical applications: ① Improve the processing performance of resins through copolymerization, blending, or other methods to solve problems such as high brittleness and easy fracture caused by solid-phase high-temperature curing molding; ② Improve toughness while ensuring that the material has sufficiently high heat resistance, mechanical properties, and mechanical strength, and prepare chemical products that combine excellent properties such as strength, toughness, heat resistance, and processability.

[0006] Commonly used chemical modifiers include polyethylene glycol, polyurethane prepolymer, polyvinyl acetal, and carboxylated nitrile rubber. While these methods can improve the toughness of cured phenolic resins to some extent, thermosetting materials such as composite materials and insulation materials have higher requirements for toughness. Therefore, we propose a method for preparing cashew nut phenol-modified thermosetting phenolic resin. Summary of the Invention

[0007] The purpose of this invention is to provide a more efficient toughening method for phenolic resins. Cashew phenol, due to its multiple hydroxyl groups and long carbon chain structure, can participate in the cross-linking reaction of the phenolic resin system in multiple dimensions, change the cross-linking structure of the system, effectively improve the comprehensive mechanical properties of the system, and significantly enhance the toughness of the material.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing cashew phenol-modified thermosetting phenolic resin includes the following steps: Step 1: Add phenol, cashew nut phenol, and catalyst to the reactor, heat to 70-90℃ and react. If the cashew nut phenol content is <1%, add a terminator. Step 2: Cool the reactor to 50-60℃, add phenol, formaldehyde, and alkaline catalyst, start stirring, heat to 70-95℃, maintain the temperature and react until the free aldehyde content is less than 1%. Perform vacuum dehydration until the viscosity is qualified, add solvent to adjust the solid content, and you can obtain cashew nut phenol modified thermosetting phenolic resin.

[0009] Preferably, the cashew phenol is refined cashew phenol, crude cashew phenol, or at least one of the following structures.

[0010] Preferably, the mass ratio of phenol:42% formaldehyde:cashew phenol is 100:80-120:60-80.

[0011] Preferably, the alkaline catalyst is ammonia, ethylenediamine, triethylamine, or at least one of the following structures.

[0012] Compared with the prior art, the beneficial effects of this invention are as follows: 1. A method for preparing cashew nut shell phenol-modified thermosetting phenolic resin. This method uses cashew nut shell phenol as a modifier. Because the molecular structure of this modifier contains benzene rings, polar hydroxyl groups and meta-unsaturated double bonds in a straight chain, the modified resin system has multiple interaction sites due to its multiple structures, which increases the interaction between the resin and the substrate. It has excellent electrical and mechanical properties, which can effectively improve the adhesion of the coating on the substrate surface, significantly improve the toughness of the material, and significantly improve the tensile strength and flexural strength of the modified resin. Its thermal stability before 300℃ is better than that of ordinary resin.

[0013] 2. The cashew phenol-modified thermosetting phenolic resin involved in this preparation method can be applied to industries such as high heat-resistant insulating laminates, copper-clad laminates, aerospace composite materials, carbonized functional materials, and high-end heat and sound insulation materials due to its excellent toughness and flame retardant properties. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0015] Example 1 First, add 80 parts phenol, 80 parts cashew nut phenol, and a catalyst to the reactor, heat to 70-90℃ and react. If the cashew nut phenol content is less than 1%, add a terminator. Second, cool the reactor to 50-60℃, add 20 parts phenol, 120 parts formaldehyde, and ammonia. Start stirring, heat to 70-95℃, and maintain the temperature until the free aldehyde content is less than 1%. Perform vacuum dehydration until the viscosity is qualified, add solvent to adjust the solid content, and you will get cashew nut phenol modified thermosetting phenolic resin.

[0016] Example 2 First, add 80 parts phenol, 120 parts cashew nut phenol, and catalyst to the reactor, heat to 70-90℃ and react. If the cashew nut phenol content is less than 1%, add a terminator. Second, cool the reactor to 50-60℃, add 20 parts phenol, 180 parts formaldehyde, and ammonia. Start stirring, heat to 70-95℃, and maintain the temperature until the free aldehyde content is less than 1%. Perform vacuum dehydration until the viscosity is qualified, add solvent to adjust the solid content, and you can obtain cashew nut phenol modified thermosetting phenolic resin.

[0017] Example 3 First, add 80 parts phenol, 90 parts cashew nut phenol, and a catalyst to a reaction vessel, heat to 70-90℃, and react until the cashew nut phenol content is <1%. Then, add a terminator. Second, cool the reaction vessel to 50-60℃, add 20 parts phenol, 150 parts formaldehyde, and triethylamine, start stirring, heat to 70-95℃, and maintain the temperature until the free aldehyde content is less than 1%. Then, perform vacuum dehydration until the viscosity is qualified, add solvent to adjust the solid content, and you can obtain cashew nut phenol modified thermosetting phenolic resin.

[0018] Example 4 First, add 80 parts phenol, 85 parts cashew nut phenol, and a catalyst to the reactor, heat to 70-90℃ and react. If the cashew nut phenol content is less than 1%, add a terminator. Second, cool the reactor to 50-60℃, add 20 parts phenol, 150 parts formaldehyde, and ethylenediamine, start stirring, heat to 70-95℃, and maintain the temperature until the free aldehyde content is less than 1%. Perform vacuum dehydration until the viscosity is qualified, add solvent to adjust the solid content, and you will get cashew nut phenol modified thermosetting phenolic resin.

[0019] Example 5 First, add 80 parts phenol, 115 parts cashew nut phenol, and a catalyst to the reactor, heat to 70-90℃ and react. If the cashew nut phenol content is less than 1%, add a terminator. Second, cool the reactor to 50-60℃, add 20 parts phenol, 140 parts formaldehyde, and ethylenediamine, start stirring, heat to 70-95℃, and maintain the temperature until the free aldehyde content is less than 1%. Perform vacuum dehydration until the viscosity is qualified, add solvent to adjust the solid content, and you can obtain cashew nut phenol modified thermosetting phenolic resin.

[0020] Example 6 First, add 80 parts phenol, 100 parts cashew nut phenol, and a catalyst to the reactor, heat to 70-90℃ and react. If the cashew nut phenol content is less than 1%, add a terminator. Second, cool the reactor to 50-60℃, add 20 parts phenol, 160 parts formaldehyde, and triethylamine, start stirring, heat to 70-95℃, and maintain the temperature until the free aldehyde content is less than 1%. Perform vacuum dehydration until the viscosity is qualified, add solvent to adjust the solid content, and you can obtain cashew nut phenol modified thermosetting phenolic resin.

[0021] The following experimental examples further illustrate the beneficial effects of the preparation method of the cashew phenol-modified thermosetting phenolic resin of the present invention: 100 grams each of unmodified phenolic resin and cashew phenol-modified thermosetting phenolic resins from Examples 1-6 were placed in an oven at 120°C for 2 hours for curing, and samples were taken to measure their impact strength. The results showed that the impact strength of the cashew phenol-modified thermosetting phenolic resins from Examples 1-6 was significantly higher than that of the unmodified phenolic resin. Specific data are shown in the table below: Resin Name <![CDATA[Impact strength kJ / m 2 > Unmodified resin 2.20 Example 1: Cashew Phenolic Resin Modified Thermosetting Phenolic Resin 3.41 Example 2: Cashew Phenolic Resin Modified Thermosetting Phenolic Resin 3.81 Example 3: Cashew Phenolic Resin Modified Thermosetting Phenolic Resin 3.46 Example 4: Cashew Phenolic Resin Modified Thermosetting Phenolic Resin 3.28 Example 5: Cashew Phenolic Resin Modified Thermosetting Phenolic Resin 3.76 Example 6: Cashew Phenolic Resin Modified Thermosetting Phenolic Resin 3.54 The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing cashew phenol-modified thermosetting phenolic resin, characterized in that, It is made by the following steps: Step 1: Add phenol, cashew nut phenol, and catalyst to the reaction vessel, heat to 70-90℃ and react. If the cashew nut phenol content is <1%, add a terminator. Step 2: Cool the reactor to 50-60℃, add phenol, formaldehyde, and alkaline catalyst, start stirring, raise the temperature to 70-95℃, maintain the temperature for reaction, and react until the free aldehyde is less than 1%. Perform vacuum dehydration until the viscosity is qualified, add solvent to adjust the solid content, and you can get cashew phenol modified thermosetting phenolic resin.

2. The method for preparing cashew phenol-modified thermosetting phenolic resin according to claim 1, characterized in that, The cashew phenol is refined cashew phenol, crude cashew phenol, or at least one of the following structures.

3. The method for preparing cashew phenol-modified thermosetting phenolic resin according to claim 1, characterized in that, The mass ratio of phenol:42% formaldehyde:cashew phenol is 100:120-180:80-120.

4. The method for preparing cashew phenol-modified thermosetting phenolic resin according to claim 1, characterized in that, The alkaline catalyst is ammonia, ethylenediamine, triethylamine, or at least one of the following structures.