Preparation of epoxy resin-modified cellulose nanoparticles by in-situ reaction method and its application

Abstract

The invention discloses an in-situ reaction method for preparing epoxy resin-modified cellulose nanoparticles and applications thereof, and belongs to the field of film materials. The method uses E44 epoxy resin and CNC as raw materials, reacts to generate CNP / E44; then adds bisphenol A to prepare CNP / EP; adds a curing agent, scrapes the film, and obtains CNP / EPF. Compared with the existing nanocellulose / organic solvent-based epoxy resin composite material, CNP‑g‑E44 prepared by the in-situ reaction method can simultaneously strengthen and toughen organic solvent-based epoxy resin films, and has good practicality.

Description

Technical Field

[0001] The invention belongs to the field of film materials, and in particular relates to a cellulose nanoparticle / epoxy resin film and a preparation method thereof, and modified cellulose nanoparticles. Background Art

[0002] Epoxy resin (EP) is the most widely used matrix resin in polymer-based composite materials. It has excellent mechanical properties, stable chemical properties, easy processing, low cost and other characteristics. It is widely used in electronic materials, aerospace and other fields. However, after the traditional EP is cured, it has the disadvantages of insufficient toughness and poor impact resistance. Therefore, it is of great significance to modify EP and improve its mechanical properties.

[0003] At present, the commonly used modification methods include nanofiller modification and chemical modification of epoxy resin or curing agent. Among them, nanofillers such as carbon nanotubes, nanosilica, graphene nanosheets and nanocellulose (CN) show good modification effects. CN has attracted widespread attention due to its advantages such as high aspect ratio, high crystallinity, wide sources and environmental friendliness. CN is a linear polymer composed of glucose structural units linked by β, 1-4 glycosidic bonds. Each glucose structural unit contains 3 hydroxyl groups, so CN has a large polarity. CN modified waterborne epoxy resin shows good reinforcement or toughening effect. However, for organic solvent-based epoxy resin, CN needs to be chemically modified. For example, cellulose nanofibers (CNF) modified with silane coupling agent and cellulose nanocrystals (CNC) modified with acetylation can improve the tensile strength of epoxy resin; CNC modified with lauroyl chloride can improve the elongation at break of epoxy resin, but neither can achieve the effect of simultaneous reinforcement and toughening. Therefore, it is of great significance to prepare a new type of nanocellulose to simultaneously reinforce and toughen organic solvent-based epoxy resin film. Summary of the invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method for preparing a cellulose nanoparticle / epoxy resin film, which has the characteristics of being simple and reliable, and can simultaneously strengthen and toughen a solvent-based 901 epoxy resin film. Another technical problem to be solved by the present invention is to provide a cellulose nanoparticle / epoxy resin film. Another technical problem to be solved by the present invention is to provide a cellulose nanoparticle (CNP-g-E44) for modifying epoxy resin film.

[0005] In order to solve the above technical problems, the technical solution adopted in this application is:

[0006] A method for preparing a cellulose nanoparticle / epoxy resin film comprises: reacting E44 epoxy resin with cellulose nanocrystals (CNC) to generate CNP / E44 (including CNP-g-E44 and E44), adding bisphenol A to generate a CNP / 901 epoxy resin composite material (CNP / EP), adding a curing agent, and scraping the film to obtain a nanocellulose particle / epoxy resin film (CNP / EPF).

[0007] The preparation method of the cellulose nanoparticle / epoxy resin film comprises the following steps:

[0008] 1) Add E44 epoxy resin and CNC into a reaction vessel, heat to 60°C, stir continuously for reaction, then heat to 120°C, add tetrabutylammonium bromide, continue reaction, and obtain CNP / E44;

[0009] 2) adding bisphenol A to CNP / E44, and keeping the mixture warm until the reaction is complete after the bisphenol A is completely dissolved; cooling the mixture to room temperature to obtain CNP / EP;

[0010] 3) adding epoxy resin diluent to dilute the CNP / EP sample, then stirring and mixing with the cardanol phenol amine curing agent, ultrasonically degassing, coating on a glass plate with a film applicator, and obtaining CNP / EPF after curing.

[0011] In the method for preparing the cellulose nanoparticle / epoxy resin film, the amount of CNC used is less than 0.7wt% of the mass of the E44 epoxy resin.

[0012] In the method for preparing the cellulose nanoparticle / epoxy resin film, the mass ratio of bisphenol A to E44 epoxy resin is 0.175.

[0013] In the method for preparing the cellulose nanoparticle / epoxy resin film, the mass ratio of tetrabutylammonium bromide to E44 epoxy resin is 0.04.

[0014] In the preparation method of the cellulose nanoparticle / epoxy resin film, the epoxy resin diluent is a mixed solution of xylene and n-butanol in a mass ratio of 4:1.

[0015] In the method for preparing the cellulose nanoparticle / epoxy resin film, the mass ratio of the cardanol phenol amine curing agent to the CNP / EP sample is equal to the epoxy value of 33.49×CNP / EP.

[0016] The preparation method of the cellulose nanoparticle / epoxy resin film comprises the following steps:

[0017] 1) 30 g of E44 epoxy resin and CNC were added to a 50 mL three-necked flask equipped with a thermometer and a condenser, heated to 60° C., stirred continuously for 3 h, then heated to 120° C., 1.2 g of tetrabutylammonium bromide was added, and reacted for 3 h to obtain CNP / E44; wherein the mass of CNC was less than 0.7 wt % of the mass of E44 epoxy resin;

[0018] 2) adding 5.25 g of bisphenol A to CNP / E44, and after the bisphenol A is completely dissolved, keeping the mixture warm for 6 h, and cooling to room temperature to obtain CNP / EP;

[0019] 3) Add epoxy resin diluent to dilute the CNP / EP sample to 60% concentration, then stir and mix with cardanol phenol amine curing agent, degas by ultrasonic, apply on a glass plate with a 1000 μm applicator, and cure at room temperature for 20 days to obtain CNP / EPF.

[0020] The cellulose nanoparticle / epoxy resin film is obtained by the preparation method of the cellulose nanoparticle / epoxy resin film.

[0021] Application of cellulose nanoparticles (CNP-g-E44) in modified epoxy resin film; the CNP-g-E44 is prepared by the following method: 30g E44 epoxy resin and CNC are added to a 50mL three-necked flask equipped with a thermometer and a condenser, heated to 60°C, stirred continuously for 3h, then heated to 120°C, 1.2g tetrabutylammonium bromide is added, and reacted for 3h to obtain CNP / E44, wherein CNP / E44 contains CNP-g-E44 and unreacted E44, and the mass of CNC is less than 0.7wt% of the mass of E44 epoxy resin.

[0022] Beneficial effects: Compared with existing nanocellulose, the technical advantages of the present invention include: the novel CNP-g-E44 prepared by the present invention can simultaneously strengthen and toughen solvent-based 901 epoxy resin film. Compared with 901 epoxy resin film, the tensile strength of CNP / EPF increased by up to 24%, and the elongation at break increased by 61%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 are the infrared spectra of CNC, E44, and CNP-g-E44;

[0024] Figure 2 These are electron microscope images of CNC and CNP-g-E44; the left image is CNC and the right image is CNP-g-E44. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments.

[0026] The cellulose nanocrystals (CNC) used in the following examples were prepared by conventional sulfuric acid hydrolysis method, and their dimensions were: a width of about 20 nm and a length of 90-200 nm.

[0027] Example 1

[0028] 1) Add 30g of E44 to a 50mL three-necked flask equipped with a thermometer and a condenser, heat to 60°C, stir continuously for 3h, then heat to 120°C, add 1.2g of tetrabutylammonium bromide, and react for 3h. Add 5.25g of bisphenol A, wait for it to completely dissolve, keep warm for 6h, and cool to room temperature to obtain EP.

[0029] 2) An epoxy resin diluent (the mass ratio of xylene to n-butanol is 4:1) was added to dilute the EP sample concentration to 60%, and then mixed with a cardanol phenol amine curing agent (PLR730, active hydrogen equivalent is 95) (the mass ratio of the cardanol phenol amine curing agent to the EP sample is equal to 33.49×the epoxy value of EP, the same below) and ultrasonically degassed, and coated on a glass plate with a 1000 μm applicator. After curing at room temperature for 20 days, a film with a thickness of about 290 μm was obtained. The sample was labeled CNP / EPF-0.

[0030] Example 2

[0031] 1) 30g E44 and CNC (0.1wt% E44) were added to a 50mL three-necked flask equipped with a thermometer and a condenser, heated to 60°C, stirred continuously for 3h, then heated to 120°C, 1.2g tetrabutylammonium bromide was added, reacted for 3h, and CNP / E44 (including CNP-g-E44 and unreacted E44) was obtained. 5.25g bisphenol A was added, and after it was completely dissolved, the temperature was kept for 6h, and cooled to room temperature to obtain CNP / EP.

[0032] 2) An epoxy resin diluent (xylene and n-butanol in a mass ratio of 4:1) was added to dilute the CNP / EP sample concentration to 60%, followed by stirring and mixing with a cardanol phenol amine curing agent (PLR730, active hydrogen equivalent of 95), ultrasonic degassing, and coating on a glass plate with a 1000 μm applicator. After curing at room temperature for 20 days, a film (CNP / EPF) with a thickness of about 290 μm was obtained. The sample was labeled CNP / EPF-0.1.

[0033] Example 3

[0034] 1) 30g F44 and CNC (0.3wt% E44) were added to a 50mL three-necked flask equipped with a thermometer and a condenser, heated to 60°C, stirred continuously for 3h, then heated to 120°C, 1.2g tetrabutylammonium bromide was added, reacted for 3h, and CNP / E44 (including CNP-g-E44 and unreacted F44) was obtained. 5.25g bisphenol A was added, and after it was completely dissolved, the mixture was kept warm for 6h and cooled to room temperature to obtain CNP / EP.

[0035] 2) An epoxy resin diluent (xylene and n-butanol in a mass ratio of 4:1) was added to dilute the CNP / EP sample concentration to 60%, followed by stirring and mixing with a cardanol phenol amine curing agent (PLR730, active hydrogen equivalent of 95), ultrasonic degassing, and coating on a glass plate with a 1000 μm applicator. After curing at room temperature for 20 days, a film (CNP / EPF) with a thickness of about 290 μm was obtained. The sample was labeled CNP / EPF-0.3.

[0036] Example 4

[0037] 1) 30g E44 and CNC (0.5wt% E44) were added to a 50mL three-necked flask equipped with a thermometer and a condenser, heated to 60°C, stirred continuously for 3h, then heated to 120°C, 1.2g tetrabutylammonium bromide was added, reacted for 3h, and CNP / E44 (including CNP-g-E44 and unreacted E44) was obtained. 5.25g bisphenol A was added, and after it was completely dissolved, the temperature was kept for 6h, and cooled to room temperature to obtain CNP / EP.

[0038] (2) An epoxy resin diluent (xylene and n-butanol in a mass ratio of 4:1) was added to dilute the CNP / EP sample concentration to 60%, and then mixed with a cardanol phenol amine curing agent (PLR730, active hydrogen equivalent of 95) and ultrasonically degassed. The sample was coated on a glass plate using a 1000 μm applicator and cured at room temperature for 20 days to obtain a film (CNP / EPF) with a thickness of about 290 μm. The sample was labeled CNP / EPF-0.5.

[0039] Example 5

[0040] 1) 30g E44 and CNC (0.7wt% E44) were added to a 50mL three-necked flask equipped with a thermometer and a condenser, heated to 60°C, stirred continuously for 3h, then heated to 120°C, 1.2g tetrabutylammonium bromide was added, reacted for 3h, and CNP / E44 (including CNP-g-E44 and unreacted E44) was obtained. 5.25g bisphenol A was added, and after it was completely dissolved, the temperature was kept for 6h, and cooled to room temperature to obtain CNP / EP.

[0041] 2) An epoxy resin diluent (xylene and n-butanol in a mass ratio of 4:1) was added to dilute the CNP / EP sample concentration to 60%, followed by stirring and mixing with a cardanol phenol amine curing agent (PLR730, active hydrogen equivalent of 95), ultrasonic degassing, and coating on a glass plate with a 1000 μm applicator. After curing at room temperature for 20 days, a film (CNP / EPF) with a thickness of about 290 μm was obtained. The sample was labeled CNP / EPF-0.7.

[0042] Example 6

[0043] The tensile properties of CNP / EPF specimens at room temperature were tested using a universal testing machine (TY8000B, TYTESTEER, China) according to GB / T 1040.3-2006 standard. The specimens were made into dumbbells with a length of 200 mm and a gauge length of 50 mm. The load cell was 5 KN, the crosshead speed was set to 20 mm / min, and at least three specimens were measured in each group. The test results of the products prepared in each embodiment are shown in Table 1.

[0044] Table 1 Product performance parameter test results

[0045]

[0046] The results in Table 1 show that the tensile strength and elongation at break of CNP / EPF-0.1, CNP / EPF-0.3, CNP / EPF-0.5 and CNP / EPF-0.7 films are higher than those of CNP / EPF-0 film, and the tensile strength and elongation at break of CNP / EPF-0.3 film are 24% and 61% higher than those of CNP / EPF-0 film, respectively. This indicates that CNP-g-E44 can simultaneously strengthen and toughen solvent-based 901 epoxy resin films.

[0047] In order to characterize the modified CNPs, the mixture of CNC and E44 (CNP / E44) was washed several times with epoxy resin diluent and centrifuged to remove the unreacted E44, and the obtained solid was dried in an oven at 60 °C for 1 h to obtain a powder sample as the modified CNP, which was labeled as CNP-g-E44.

[0048] CNC, E44 and CNP-g-E44 were characterized by infrared spectroscopy. Figure 2 As shown, E44 at 1510cm -1 The vibration peak of the benzene ring is shown at 1454cm. CNP-g-E44 also has a vibration peak here, indicating that CNP is grafted with E44. -1 The stretching vibration peak of ester bond CO is shown at 1430 cm-1, while the absorption peak of CNP-g-E44 at this point shifts to 1430 cm-1. -1This proves that the ester bonds in CNC are broken and CNC is broken into CNP.

[0049] CNC and CNP-g-E44 were characterized by scanning electron microscopy. Figure 2 As shown, the width of CNC is about 20 nm and the length is 90-200 nm; CNP-g-E44 is a nanoparticle with a particle size of 50-100 nm.

[0050] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A method for preparing a cellulose nanoparticle / epoxy resin film, characterized in that: E44 epoxy resin reacts with CNC to generate CNP / E44, then bisphenol A is added to generate CNP / EP, curing agent is added, and film is scraped to obtain CNP / EPF; the steps are as follows: 1) Add E44 epoxy resin and CNC into a reaction vessel, heat to 60°C, stir continuously for reaction, then heat to 120°C, add tetrabutylammonium bromide, continue reaction, and obtain CNP / E44; 2) Add bisphenol A to CNP / E44, wait for it to completely dissolve, and keep warm until the reaction is complete; cool to room temperature to obtain CNP / EP; 3) Add epoxy resin diluent to dilute CNP / EP sample, then stir and mix with cardanol phenol amine curing agent, perform ultrasonic degassing, apply on glass plate with applicator, and obtain CNP / EPF after curing; The amount of CNC used is less than 0.7wt% of the mass of the E44 epoxy resin; and the mass ratio of bisphenol A to the E44 epoxy resin is 0.

175.

2. The method for preparing the cellulose nanoparticle / epoxy resin film according to claim 1, characterized in that: The mass ratio of tetrabutylammonium bromide to E44 epoxy resin is 0.

04.

3. The method for preparing the cellulose nanoparticle / epoxy resin film according to claim 1, characterized in that: The epoxy resin diluent is a mixed solution of xylene and n-butanol in a mass ratio of 4:

1.

4. The method for preparing the cellulose nanoparticle / epoxy resin film according to claim 1, characterized in that: The mass ratio of cardanol phenol amine curing agent to CNP / EP sample is equal to 33.49×the epoxy value of CNP / EP.

5. The method for preparing the cellulose nanoparticle / epoxy resin film according to claim 1, characterized in that: Here are the steps: 1) Add 30g E44 epoxy resin and CNC into a 50mL three-necked flask equipped with a thermometer and a condenser, heat to 60°C, stir continuously for 3h, then heat to 120°C, add 1.2g tetrabutylammonium bromide, react for 3h to obtain CNP / E44; wherein the mass of CNC is less than 0.7wt% of the mass of F44 epoxy resin; 2) Add 5.25 g of bisphenol A to CNP / E44, wait for it to completely dissolve, keep warm for 6 hours, and cool to room temperature to obtain CNP / EP; 3) Epoxy resin diluent was added to dilute the CNP / EP sample to 60% concentration, and then mixed with cardanol phenol amine curing agent, ultrasonically degassed, and coated on a glass plate with a 1000 μm applicator. After curing at room temperature for 20 days, nanocellulose particles / epoxy resin film CNP / EPF was obtained.

6. The cellulose nanoparticle / epoxy resin film obtained by the method for preparing the cellulose nanoparticle / epoxy resin film according to any one of claims 1 to 5.

7. Application of CNP-g-E44 in modified epoxy resin film; the CNP-g-E44 is prepared by the following method: 30g of E44 epoxy resin and CNC are added to a 50mL three-necked flask equipped with a thermometer and a condenser, heated to 60°C, stirred continuously for 3h, then heated to 120°C, 1.2g of tetrabutylammonium bromide is added, and reacted for 3h to obtain CNP / E44; wherein, CNP / E44 contains CNP-g-E44 and unreacted E44, and the mass of CNC is less than 0.7 wt % of the mass of E44 epoxy resin.

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