CN116554438A - Preparation method of cardanol modified epoxy resin - Google Patents

Abstract

The invention belongs to the technical field of epoxy resin modification, and particularly relates to a preparation method of cardanol modified epoxy resin. The cardanol modified epoxy resin is prepared by adding the cardanol with the epoxy groups of the epoxy resin under the action of the catalyst, and the cardanol modified epoxy resin prepared by the invention has excellent water resistance, strength and toughness, and the prepared coating can realize low-temperature curing.

Description

A kind of preparation method of cardanol modified epoxy resin

technical field

The invention belongs to the technical field of epoxy resin modification, and in particular relates to a preparation method of cardanol-modified epoxy resin.

Background technique

Epoxy resin generally refers to a polymer containing two or more epoxy groups in the molecule, which has excellent adhesion, mechanical properties, electrical insulation properties, chemical stability, high and low temperature resistance, and low shrinkage, It has the advantages of easy processing and forming, better stress transmission and low cost. It is widely used in the fields of adhesives, electronic instruments, light industry, construction, machinery, aerospace, coatings, bonding, electronic and electrical insulation materials, and advanced composite material substrates.

Epoxy resin is a thermosetting material with a high degree of cross-linking. It has a three-dimensional network structure in space. The molecular chains are not easy to slide, and the internal stress is large, which leads to problems such as insufficient toughness, poor impact resistance and easy cracking after curing. . Therefore, how to realize epoxy resin softening and toughening modification technology has always been a subject of great concern. Traditional epoxy resin toughening, such as rubber elastomer toughening epoxy resin, has obvious toughening effect, but it will reduce the heat resistance and modulus of the system. Although the thermoplastic resin toughened epoxy resin does not reduce the material modulus and heat resistance, it is used in a large amount, has poor solubility and fluidity, and is difficult to cure and form a film. TLCP toughened epoxy resin can significantly improve toughness with less dosage, but its cost is high and processing is difficult. Therefore, the paint industry urgently needs to find a modified epoxy resin that is low in cost, curable at low temperature, and has excellent water resistance and toughness of the paint film after curing.

Contents of the invention

In view of this, the purpose of the present invention is to provide a kind of preparation method of cardanol modified epoxy resin, the cardanol modified epoxy resin prepared by the present invention has excellent water resistance, strength and toughness, and the coating prepared by it can realize Curing at low temperature.

In order to achieve the above object, the present invention provides the following technical solutions:

The invention provides a kind of preparation method of cardanol modified epoxy resin, comprising the following steps:

The liquid epoxy resin, cardanol and catalyst are mixed, and the ring-opening addition reaction is carried out to obtain the cardanol-modified epoxy resin.

Preferably, the liquid epoxy resin is E51 liquid epoxy resin and/or E54 liquid epoxy resin.

Preferably, the epoxy equivalent of the liquid epoxy resin is 180-190 g/eq.

Preferably, the catalyst is triphenylphosphine and/or triphenylphosphine derivatives.

Preferably, the triphenylphosphine derivatives include one of bromobutyltriphenylphosphine, ethyltriphenylphosphine chloride, ethyltriphenylphosphine bromide and ethyltriphenylphosphine iodide species or several.

Preferably, the mass of the catalyst is 0.5-1% of the mass of the liquid epoxy resin.

Preferably, the mass ratio of the cardanol to the liquid epoxy resin is (20-30):(90-100).

Preferably, the temperature of the ring-opening addition reaction is 100-120° C.; the time of the ring-opening addition reaction is 2-3 hours.

Preferably, the heating rate to the ring-opening addition reaction temperature is 0.5-1° C./min.

Preferably, after the ring-opening addition reaction, further comprising: cooling the product obtained in the ring-opening addition reaction to room temperature through a cold water bath.

The invention provides a preparation method of cardanol-modified epoxy resin, comprising the following steps: mixing liquid epoxy resin, cardanol and a catalyst, and performing ring-opening addition reaction to obtain cardanol-modified epoxy resin. The present invention utilizes cardanol to add the epoxy group of epoxy resin under the action of catalyst to prepare cardanol modified epoxy resin. Cardanol is a mixture of phenolic compounds with unsaturated long side chain hydrocarbon groups, and its benzene ring has Rigidity can improve the strength of cardanol modified epoxy resin. There is a hydrophobic force between the longer hydrophobic chains in its molecular structure. The hydrophobic chain can hinder the infiltration of water molecules, so that it has excellent water resistance and can also limit Molecular diffusion makes the coating based on cardanol-modified epoxy resin have a longer pot life; the flexible long-chain alkane structure in cardanol can enhance the flexibility of cardanol-modified epoxy resin, thereby improving its toughness, and cardanol The phenolic hydroxyl group in it is a polar group, which can provide better bonding performance, reduce reactivity, and accelerate resin reaction. The coating prepared by cardanol-modified epoxy resin can be cured at room temperature or low temperature, and the cardanol-modified epoxy resin can be shortened. The coating cycle of epoxy resin coating.

Detailed ways

The invention provides a kind of preparation method of cardanol modified epoxy resin, comprising the following steps:

The liquid epoxy resin, cardanol and catalyst are mixed, and the ring-opening addition reaction is carried out to obtain the cardanol-modified epoxy resin.

Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used for the preparation, and commercially available products well known to those skilled in the art can be used.

The invention mixes the liquid epoxy resin, the cardanol and the catalyst to obtain the mixture.

In the present invention, the liquid epoxy resin is preferably E51 liquid epoxy resin and/or E54 liquid epoxy resin, more preferably E51 liquid epoxy resin; when the liquid epoxy resin is E51 liquid epoxy resin and E54 liquid epoxy resin When epoxy resin, the present invention has no special limitation to the proportioning of two kinds of liquid epoxy resins, any proportioning all can; The epoxy equivalent of described liquid epoxy resin is preferably 180～190g/eq, is more preferably 182～ 188g/eq.

In the present invention, the catalyst is preferably triphenylphosphine and/or triphenylphosphine derivatives, more preferably triphenylphosphine derivatives; the triphenylphosphine derivatives preferably include bromobutyltriphenyl One or more of base phosphine, ethyl triphenyl phosphine chloride, ethyl triphenyl phosphine bromide and ethyl triphenyl phosphine iodide, more preferably bromobutyl triphenyl phosphine, ethyl triphenyl phosphine Triphenylphosphine chloride or ethyltriphenylphosphine bromide; when the catalyst is multiple, the present invention has no special limitation on the proportioning of different types of catalysts, any proportioning can be; the quality of the catalyst is preferably The mass of the liquid epoxy resin is 0.5-1%, more preferably 0.5-0.8%.

In the present invention, the mass ratio of the cardanol to the liquid epoxy resin is preferably (20-30):(90-100), more preferably (20-27):(90-100).

Cardanol is the main component of cashew nutshell liquid (CNSL), and its chemical structure is a phenol structure containing long-chain unsaturated alkanes, which is biorenewable and low in price.

In the present invention, CNSL modified epoxy resin is prepared by adding cardanol to the epoxy group of epoxy resin under the action of a catalyst. The phenolic hydroxyl group in the CNSL structure can provide better bonding performance, reduce reactivity, accelerate resin reaction, and realize The low-temperature curing of the coating shortens the coating cycle, and the hydrophobic force between the longer hydrophobic chains in its molecular structure can limit the molecular diffusion on the one hand, making the coating based on CNSL modified epoxy resin have a longer application period, and on the other hand On the one hand, it can improve the hydrophobicity of the paint film, and the hydrophobic chain can hinder the infiltration of water molecules and improve the water resistance of the paint film; the flexible long-chain alkane structure in cardanol can enhance the flexibility of cardanol-modified epoxy resin, thereby improving its toughness.

After the mixture is obtained, the present invention performs ring-opening addition reaction on the mixture to obtain the cardanol-modified epoxy resin.

In the present invention, the temperature of the ring-opening addition reaction is preferably 100-120°C, more preferably 110-120°C; the time of the ring-opening addition reaction is preferably 2-3h, more preferably 2h; The temperature rise rate to the ring-opening addition reaction temperature is preferably 0.5-1°C/min, more preferably 0.6-0.8°C/min; the ring-opening addition reaction is preferably carried out under stirring conditions; the stirring The speed is preferably 130-150 r/min, more preferably 140-150 r/min.

After the ring-opening addition reaction, the present invention preferably further includes: cooling the product obtained in the ring-opening addition reaction to room temperature through a cold water bath; the room temperature is preferably 24-30°C, more preferably 24-29°C.

The invention utilizes the phenolic hydroxyl group of cardanol to be easily added to the epoxy group under the action of a catalyst to prepare the CNSL modified epoxy resin, which can improve the water resistance and toughness of the paint film, and make the cured coating have stronger toughness and strength and water resistance.

The coating prepared by the cardanol-modified epoxy resin prepared by the invention can realize low-temperature curing, shorten the coating period, reduce coating defects, and the biological regeneration of raw materials is low in price, and no three wastes are generated in the preparation process. The preparation method of the invention has simple process, easy operation and convenient industrial implementation.

The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, but they should not be construed as limiting the protection scope of the present invention.

Example 1

Get 95gE51 liquid epoxy resin (epoxy equivalent 186.6g/eq, viscosity is 12680cp.s), 23g cardanol and 0.76g bromobutyltriphenylphosphine are added in 500mL four-necked bottle, and the resulting mixture is stirred at 130rpm to Raise the temperature at 0.5°C/min to 100°C for 2 hours, then cool down to 26°C and take it out to obtain a cardanol-modified epoxy resin. After testing, the modified viscosity is 25630cp.s.

Example 2

Get 90gE51 liquid epoxy resin (epoxy equivalent 182.8g/eq, viscosity is 14200cp.s), 25g cardanol and 0.9g ethyltriphenylphosphine chloride are added in a 500mL four-necked bottle, and the resulting mixture is stirred at 140rpm to Raise the temperature at 0.6°C/min to 105°C for 2 hours, then cool down to 24°C and take it out to obtain a cardanol-modified epoxy resin. After testing, the modified viscosity is 26800cp.s.

Example 3

Get 100gE51 liquid epoxy resin (epoxy equivalent 184.6g/eq, viscosity is 14000cp.s), 20g cardanol and 0.6g ethyltriphenylphosphine bromide are added in 500mL four-necked bottle, and the resulting mixture is stirred at 145rpm to Raise the temperature at 1°C/min to 115°C for 2 hours, then cool down to 29°C and take it out to obtain a cardanol-modified epoxy resin. After testing, the modified viscosity is 24630cp.s.

Example 4

Get 98gE51 liquid epoxy resin (epoxy equivalent 187.5g/eq, viscosity is 13500cp.s), 24g cardanol and 0.784g bromobutyltriphenylphosphine are added in 500mL four-necked bottle, and the resulting mixture is stirred at 150rpm to Raise the temperature at 0.8°C/min to 120°C for 2 hours, then cool down to 27°C and take it out to obtain a cardanol-modified epoxy resin. After testing, the modified viscosity is 25200cp.s.

Example 5

Get 93gE51 liquid epoxy resin (epoxy equivalent 183.7g/eq, viscosity is 13050cp.s), 27g cardanol and 0.651g ethyltriphenylphosphine iodide are added in 500mL four-necked bottle, and the resulting mixture is stirred at 140rpm to Raise the temperature at 0.7°C/min to 117°C for 2 hours, then cool down to 24°C and take it out to obtain a cardanol-modified epoxy resin. After testing, the modified viscosity is 26730cp.s.

Performance Testing

Add 20g of the cardanol-modified epoxy resin obtained in Examples 1 to 5 to 12g of N,N-dimethylbenzylamine (BDMA) and 8g of methylhexahydrophthalic anhydride (MeHHPA) to carry out the curing experiment. The test standard is GB/T 2423.5-2019, the results are shown in Table 1.

The performance test result of the cardanol-modified epoxy resin cured product that table 1 embodiment 1～5 obtains

It can be seen from Table 1 that the forward impact strength of the cardanol-modified epoxy resin cured product prepared by the present invention is 45-65J/cm ² , which is much higher than the blank sample's forward impact strength of 9-11J/cm ² ; The reverse impact strength of the cardanol-modified epoxy resin is 30-50J/cm ² , much higher than the blank sample reverse impact strength 5-6J/cm ² , indicating that the cardanol-modified epoxy resin prepared by the present invention The cured product formed has excellent toughness.

Although the foregoing embodiment has described the present invention in detail, it is only a part of the embodiments of the present invention rather than all embodiments, and people can also obtain other embodiments according to the present embodiment without inventive step, and these embodiments are all Belong to the protection scope of the present invention.

Claims (10)

1. The preparation method of the cardanol modified epoxy resin is characterized by comprising the following steps of:

mixing liquid epoxy resin, cardanol and a catalyst, and performing ring-opening addition reaction to obtain cardanol modified epoxy resin.

2. The method of claim 1, wherein the liquid epoxy resin is E51 liquid epoxy resin and/or E54 liquid epoxy resin.

3. The preparation method according to claim 1 or 2, wherein the liquid epoxy resin has an epoxy equivalent of 180 to 190g/eq.

4. The process according to claim 1, wherein the catalyst is triphenylphosphine and/or a triphenylphosphine derivative.

5. The preparation method according to claim 4, wherein the triphenylphosphine derivative comprises one or more of butyl triphenylphosphine bromide, ethyl triphenylphosphine chloride, ethyl triphenylphosphine bromide and ethyl triphenylphosphine iodide.

6. The method according to claim 1, 2, 4 or 5, wherein the mass of the catalyst is 0.5 to 1% of the mass of the liquid epoxy resin.

7. The preparation method according to claim 1, wherein the mass ratio of cardanol to liquid epoxy resin is (20-30): 90-100.

8. The method according to claim 1 or 7, wherein the temperature of the ring-opening addition reaction is 100 to 120 ℃; the time of the ring-opening addition reaction is 2-3 h.

9. The method according to claim 8, wherein the rate of temperature rise to the ring-opening addition reaction temperature is 0.5 to 1 ℃/min.

10. The method according to claim 1, further comprising, after the ring-opening addition reaction: and cooling the product obtained by the ring-opening addition reaction to room temperature through a cold water bath.