CN114015017A - Cellulose-based epoxy resin and preparation method and application thereof - Google Patents

Cellulose-based epoxy resin and preparation method and application thereof Download PDF

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CN114015017A
CN114015017A CN202111191738.7A CN202111191738A CN114015017A CN 114015017 A CN114015017 A CN 114015017A CN 202111191738 A CN202111191738 A CN 202111191738A CN 114015017 A CN114015017 A CN 114015017A
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cellulose
epoxy resin
sodium
reaction
based epoxy
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朱新宝
张彤彤
姚玉成
余敏
谈继淮
程振朔
李大钱
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Anhui Xinyuan Technology Co ltd
Nanjing Forestry University
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Anhui Xinyuan Technology Co ltd
Nanjing Forestry University
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    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
    • C08G59/02—Polycondensates containing more than one epoxy group per molecule
    • C08G59/04—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins

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Abstract

The invention provides a cellulose-based epoxy resin and a preparation method and application thereof, relates to the technical field of organic synthesis, and is characterized in that a small amount of the cellulose-based epoxy resin prepared by the invention is doped into bisphenol A epoxy resin, so that the mechanical property of a cured bisphenol A epoxy resin can be obviously improved, the application is wide, the high-added-value utilization of waste agriculture and forestry resources is effectively realized, the ecological environment pressure is reduced, and the strategic idea of sustainable development is met. The preparation method provided by the invention is simple and the product performance is excellent.

Description

Cellulose-based epoxy resin and preparation method and application thereof
Technical Field
The invention relates to the technical field of organic synthesis, in particular to cellulose-based epoxy resin and a preparation method and application thereof.
Background
Bisphenol A type epoxy resin (EP) has the advantages of higher storage stability, good processability, flexible and various formula design, lower volume shrinkage rate in the curing process and the like, and an EP cured product has excellent mechanical property, chemical resistance, electrical property and adhesive property, so the EP cured product is widely applied to the fields of machinery, electronics and electricity, aerospace, transportation, buildings and the like as a thermosetting resin. However, the EP has high crosslinking density after curing, and the cured product has poor toughness, thereby limiting the application range of the EP to a certain extent. At present, the commonly adopted toughening methods mainly comprise rubber elastomer toughening, thermoplastic resin toughening, inorganic rigid particle toughening, Interpenetrating Polymer Networks (IPNs) toughening and the like.
In recent years, with the increasing awareness of environmental protection, bio-based resin materials are becoming one of the research hotspots in this field. In order to improve the toughness of bisphenol a epoxy resins, various environmentally friendly renewable materials have been developed. Some renewable materials have been successfully applied to significantly improve the fracture properties of bisphenol a type epoxy resins, such as soybean oil, castor oil, palm oil, tung oil, cardanol, rosin, and the like. But soybean oil and castor oil may damage the tensile strength and the glass transition temperature of the material due to a flexible structure. Among them, cellulose is abundant in natural sources, mainly from lignocellulose, which is a main component in most agricultural and forestry wastes and non-grain biomass, and is a natural polymer material with good biocompatibility, so that the utilization of cellulose has become a research hotspot in the fields of chemistry, chemical engineering and material science. However, when used as a polymer material, the polymer material has a problem of insufficient processability, and modification is usually required to improve the processability, the composite compatibility with other materials, and the like. The currently common modification methods mainly include etherification modification, esterification modification, oxidation modification and the like. The cellulose is used as a raw material, and the epoxy resin prepared by graft modification replaces or partially replaces the non-renewable petroleum-based epoxy resin toughening agent, so that the method has great significance in leading the material industry to green, environment-friendly and sustainable development. At present, reports that the bio-based liquid epoxy resin prepared by modifying cellulose serving as a raw material is used for toughening the bisphenol A epoxy resin are not found.
Disclosure of Invention
The invention aims to provide a cellulose-based epoxy resin and a preparation method and application thereof, a small amount of the cellulose-based epoxy resin provided by the invention is doped into bisphenol A epoxy resin, the mechanical property of a cured bisphenol A epoxy resin can be obviously improved, the application is wide, the high-added-value utilization of waste agriculture and forestry resources is effectively realized, the ecological environment pressure is reduced, and the strategic idea of sustainable development is met. The preparation method provided by the invention is simple and the product performance is excellent.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a cellulose-based epoxy resin, which has a structure shown in a formula I:
Figure BDA0003301413780000021
in the formula I, R1～R5Independently comprises H,
Figure BDA0003301413780000022
n、n1And n2Is the degree of polymerization; n is1Is 2 to 5; n is2Is 2 to 5.
The invention provides a preparation method of cellulose-based epoxy resin, which comprises the following steps:
mixing sodium cellulose and an epoxy compound in an organic solvent, and carrying out ring-opening addition reaction to obtain liquid cellulose polyether sodium;
and mixing the liquid cellulose polyether sodium and epichlorohydrin, and carrying out epoxidation reaction to obtain the cellulose-based epoxy resin.
Preferably, the epoxy compound is one or both of ethylene oxide and propylene oxide.
Preferably, the mass ratio of the epoxy compound to the sodium cellulose is 5-10: 1.
Preferably, the organic solvent comprises diethoxymethane, dipropoxymethane, dibutoxymethane, glyme, diglyme, toluene, xylene or 1, 4-dioxane.
Preferably, the mass ratio of the organic solvent to the sodium cellulose is 3-20: 1.
Preferably, the temperature of the ring-opening addition reaction is 70-130 ℃; the time of the ring-opening addition reaction is 2-8 h.
Preferably, the molar ratio of the liquid cellulose polyether sodium to the epichlorohydrin is 1: 3-20.
Preferably, the temperature of the epoxidation reaction is 30-80 ℃; the time of the epoxidation reaction is 1-6 h.
The invention provides application of the cellulose-based epoxy resin prepared by the technical scheme or the preparation method in the technical scheme in toughening of bisphenol A epoxy resin.
The invention provides a cellulose-based epoxy resin, wherein the structure of the cellulose-based epoxy resin contains a rigid skeleton sugar ring, so that the rigidity strength of an epoxy system can be improved; in addition, because a large amount of epoxy compounds are grafted, the C-O-C chain segment is increased, the number of flexible chain segments is increased, the brittleness of pure E-51 can be reduced, and the toughness of the cured epoxy resin is improved.
The invention provides a preparation method of cellulose-based epoxy resin, which comprises the steps of carrying out ring-opening addition reaction on sodium cellulose (alkali cellulose) serving as a raw material and an epoxy compound to prepare liquid cellulose polyether sodium, and then reacting the liquid cellulose polyether sodium with epichlorohydrin to prepare the low-viscosity liquid cellulose-based epoxy resin. The cellulose-based epoxy resin prepared by the invention has the viscosity of 1000-2500 mPa & s, the epoxy value of 0.25-0.35 eq/100g, and long and flexible chain segments (C-O-C chain segments) contained in molecules, and can be doped into bisphenol A epoxy resin, so that the mechanical property of a cured bisphenol A epoxy resin can be obviously improved. The invention organically combines the cellulose alkali activation and the epoxidation process for preparing the epoxy resin, catalyzes the ring opening addition of an epoxy compound after alkali activation of cellulose (alkali cellulose), and further uses the cellulose alkali activation and the alkali activation as a catalyst for the ring opening reaction of epoxy chloropropane and a ring-closing reaction raw material. The low-viscosity cellulose-based epoxy resin is prepared by using the bio-based cellulose as a raw material, is an excellent modifier of bisphenol A epoxy resin, can effectively realize the effective utilization of waste agriculture and forestry resources, reduces the ecological environment pressure, conforms to the strategic idea of sustainable development, and provides a strategy for the high-valued utilization of the cellulose.
Drawings
FIG. 1 is an infrared spectrum of sodium cellulose, sodium cellulose polyether prepared in example 5 and sodium cellulose polyether prepared in example 7;
FIG. 2 is an infrared spectrum of the cellulose-based epoxy resin prepared in example 5;
FIG. 3 is an infrared spectrum of the cellulose-based epoxy resin prepared in example 7.
Detailed Description
The invention provides a cellulose-based epoxy resin, which has a structure shown in a formula I:
Figure BDA0003301413780000041
in the formula I, R1～R5Independently comprises H,
Figure BDA0003301413780000042
n、n1And n2Is the degree of polymerization; n is1Is 2 to 5; n is2Is 2 to 5. In the invention, n is preferably 50-200.
In the present invention, the epoxy value of the cellulose-based epoxy resin is preferably 0.25 to 0.35eq/100g, more preferably 0.29 to 0.34eq/100g, and still more preferably 0.31 to 0.33eq/100 g.
The invention provides a preparation method of cellulose-based epoxy resin, which comprises the following steps:
mixing sodium cellulose and an epoxy compound in an organic solvent, and carrying out ring-opening addition reaction to obtain liquid cellulose polyether sodium;
and mixing the liquid cellulose polyether sodium and epichlorohydrin, and carrying out epoxidation reaction to obtain the cellulose-based epoxy resin.
In the present invention, if not specifically required, the starting materials for the preparation are commercially available products known to those skilled in the art.
The method comprises the steps of mixing sodium cellulose and an epoxy compound in an organic solvent, and carrying out ring-opening addition reaction to obtain the liquid cellulose polyether sodium. In the present invention, the preparation method of the sodium cellulose preferably includes: soaking a cellulose raw material in a sodium hydroxide solution, carrying out alkalization treatment, and sequentially squeezing, drying and crushing an obtained alkalization system to obtain the sodium cellulose. In the invention, the mass concentration of the sodium hydroxide solution is preferably 10-20%. In the invention, the temperature of the alkalization treatment is preferably 5-30 ℃; the time of the alkalization treatment is preferably 1-3 h. In the invention, the method for treating the cellulose by using the alkali has mild conditions, relatively short time and low energy consumption, meanwhile, the reaction activity of the cellulose can be improved by the alkali treatment, and the sodium cellulose with better processing and reaction performances is obtained.
In the present invention, the epoxy compound is one or both of ethylene oxide and propylene oxide; when the epoxy compound is a mixture of ethylene oxide and propylene oxide, the mass ratio of the ethylene oxide to the propylene oxide is preferably 1-2: 5-6, and more preferably 2: 5.
In the invention, the mass ratio of the epoxy compound to the sodium cellulose is preferably 5-10: 1, and more preferably 6-8: 1.
In the present invention, the organic solvent preferably includes diethoxymethane, dipropoxymethane, dibutoxymethane, glyme (DME), diglyme (DMDE), toluene, xylene, or 1, 4-dioxane. In the invention, the mass ratio of the organic solvent to the sodium cellulose is preferably 3-20: 1, and more preferably 4-10: 1.
In the present invention, the method of mixing the sodium cellulose and the epoxy compound in the organic solvent preferably includes: mixing sodium cellulose and an organic solvent to obtain a sodium cellulose solution; then adding the obtained sodium cellulose solution into a reaction kettle, N2Displacing and heating to a given reaction temperature, adding an epoxy compound at a certain feeding speed, and carrying out ring-opening addition reaction.
In the invention, the epoxy compound is continuously fed for 1-6 h, the reaction is carried out for 1-2 h under the condition of heat preservation, and the pressure is not reduced at the moment.
In the invention, the temperature of the epoxide ring-opening addition reaction is preferably 70-130 ℃, and more preferably 90-100 ℃; the time of the epoxide ring-opening addition reaction is preferably 2-8 h, and more preferably 4-5 h. In the present invention, the pressure of the epoxide ring-opening addition reaction is preferably not more than 0.8MPa, more preferably 0.6 MPa.
According to the invention, preferably, after the epoxide ring-opening addition reaction, the obtained system is cooled to 30-50 ℃, and then the organic solvent is removed through distillation, so as to obtain the liquid cellulose polyether sodium.
After the liquid cellulose polyether sodium is obtained, the liquid cellulose polyether sodium and epoxy chloropropane are mixed for epoxidation reaction to obtain the cellulose-based epoxy resin.
In the invention, the molar ratio of the liquid cellulose polyether sodium to the epichlorohydrin is preferably 1: 3-20, more preferably 1: 4-12, and further preferably 1: 7.
In the present invention, the method for mixing liquid cellulose polyether sodium and epichlorohydrin preferably comprises: adding epichlorohydrin dropwise to the liquid cellulose polyether sodium. In the invention, the dripping time of the epoxy chloropropane is preferably 1-6 h, and more preferably 2-5 h. The invention adopts a dripping mode, has the advantage of stable reaction, and can prevent sudden temperature rise caused by violent reaction from influencing the product quality and causing danger.
In the invention, the temperature of the epoxidation reaction is preferably 30-80 ℃, and more preferably 40-50 ℃; the heat preservation time of the epoxidation reaction is preferably 1-4 h, more preferably 2-3 h, and the heat preservation time of the epoxidation reaction is counted when all the epoxy chloropropane is dripped.
In the present invention, after the epoxidation reaction, it is preferable to sequentially subject the obtained reaction system to suction filtration and refining treatment, and then remove excess epichlorohydrin by distillation under reduced pressure to obtain the cellulose-based epoxy resin. In the invention, the refining treatment comprises the steps of neutralization by phosphoric acid, adsorption by activated clay and a refining agent of magnesium silicate, and suction filtration.
In the present invention, the cellulose-based epoxy resin is liquid at normal temperature. The viscosity of the cellulose-based epoxy resin prepared by the invention is preferably 1000-2500 mPas, and more preferably 1500-2100 mPas. The cellulose-based epoxy resin prepared by the invention is far lower than the viscosity (between 10000-12000 mPa & s) of pure bisphenol A epoxy resin.
The invention provides application of the cellulose-based epoxy resin prepared by the technical scheme or the preparation method in the technical scheme in toughening of bisphenol A epoxy resin. In the present invention, the method of application preferably comprises: and mixing the cellulose-based epoxy resin, the bisphenol A epoxy resin and a curing agent, and curing to obtain a cured product. In the invention, the cellulose-based epoxy resin preferably accounts for 5-20% of the bisphenol A epoxy resin by mass. In the present invention, the bisphenol A type epoxy resin is preferably E-51 epoxy resin; the curing agent is preferably a diethylenetriamine curing agent. In the embodiment of the present invention, the curing preferably comprises sequential processes of overnight curing at room temperature, curing at 80 ℃ for 3h, and aging at room temperature for 7 days.
The cellulose-based epoxy resin prepared by the invention can obviously improve the tensile strength, the elongation at break and the impact strength of a cured product of the bisphenol A epoxy resin.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The sodium cellulose in the following examples is supplied by Duyan fiber GmbH;
ethylene Oxide (EO), Propylene Oxide (PO), diethoxymethane, dibutoxymethane, diglyme, and toluene, provided by new materials chenozu gmbh;
epichlorohydrin (ECH), bisphenol A epoxy resin (E-51) and diethylenetriamine are provided by the company of New and far science and technology, Anhui, of industrial grade;
both the hydrochloric acid and acetone were analytically pure and were provided by Nanjing chemical reagents, Inc.
Detecting the epoxy value of the cellulose-based epoxy resin by using a hydrochloric acid-acetone method;
FTIR tests were performed using a U.S. Nicolet FTIR-360 Fourier transform Infrared spectrometer: the potassium bromide coating method is adopted, and the measuring range is 400-4000 cm-1。
The dosage of the curing agent refers to the book of curing agent of chemical industry publishers, diethylenetriamine is the curing agent of the epoxy resin condensate, and the calculation formula of the dosage is as follows:
G＝(M×E)/Hn
in the formula: g-grams of amine, G, required to cure 100G of epoxy resin; m-molecular weight of amine, g/mol; e-epoxy number of epoxy resin, eq/100 g; the total number of active hydrogens in the Hn-amine molecule.
Example 1
Adding 30g of sodium cellulose and 120g of dibutoxymethane into a high-pressure reaction kettle, replacing 3 times with nitrogen, starting a stirrer, slowly heating to 70 ℃, continuously introducing EO to 180g within 2 hours, controlling the reaction temperature to be 90 ℃, after the EO is added, keeping the reaction pressure to be lower than 0.7MPa, and keeping the temperature for reaction for 1 hour, wherein the reaction pressure is not reduced any more; cooling to 30 ℃, releasing pressure and discharging to obtain a cellulose polyether sodium solution, and distilling to remove dibutoxymethane to obtain cellulose polyether sodium;
adding the cellulose polyether sodium into a four-neck flask provided with a reflux condenser tube, a thermometer and a constant-pressure dropping funnel, heating to 40 ℃, and performing reaction according to the formula (n) of the cellulose polyether sodium: and (n) (ECH) is dropwise added with ECH according to the proportion of 1:6, after 1h of dropwise addition is finished, the mixture reacts for 4h at the temperature of 40 ℃, after the reaction is finished, the mixture is filtered, refined, and then the excessive ECH is removed by distillation (the vacuum degree is controlled to be-0.09 MPa, the kettle temperature is lower than 130 ℃) to prepare the cellulose-based epoxy resin, wherein the epoxy value is 0.33eq/100g, and the viscosity is 1100 mPas.
Example 2
Adding 30g of sodium cellulose and 120g of toluene into a high-pressure reaction kettle, replacing 3 times with nitrogen, starting a stirrer, slowly heating to 70 ℃, continuously introducing EO to 180g within 3 hours, controlling the reaction temperature to be 100 ℃, after EO is added, keeping the reaction pressure to be lower than 0.6MPa, and keeping the temperature for reaction for 1 hour, wherein the reaction pressure is not reduced any more; reducing the temperature to 50 ℃, then decompressing and discharging to obtain a cellulose polyether sodium solution, and distilling to remove toluene to obtain cellulose polyether sodium;
adding the cellulose polyether sodium into a four-neck flask provided with a reflux condenser tube, a thermometer and a constant-pressure dropping funnel, heating to 40 ℃, and performing reaction according to the formula (n) of the cellulose polyether sodium: and n (ECH) is dropwise added with ECH according to the proportion of 1:5, after 2h of dropwise addition is finished, the mixture reacts for 3h at the temperature of 40 ℃, after the reaction is finished, the mixture is filtered, refined, and then the excessive ECH is removed by distillation (the vacuum degree is controlled to be-0.09 MPa, the kettle temperature is lower than 130 ℃) to prepare the cellulose-based epoxy resin, wherein the epoxy value is 0.31eq/100g, and the viscosity is 1300 mPas.
Example 3
Adding 30g of sodium cellulose and 150g of toluene into a high-pressure reaction kettle, replacing 3 times with nitrogen, starting a stirrer, slowly heating to 80 ℃, continuously introducing EO to 180g within 2 hours, controlling the reaction temperature to be 100 ℃, after EO is added, keeping the reaction pressure to be lower than 0.7MPa, and keeping the temperature for reaction for 1 hour, wherein the reaction pressure is not reduced any more; reducing the temperature to 40 ℃, then decompressing and discharging to obtain a cellulose polyether sodium solution, and distilling to remove toluene to obtain cellulose polyether sodium;
adding the cellulose polyether sodium into a four-neck flask provided with a reflux condenser tube, a thermometer and a constant-pressure dropping funnel, heating to 40 ℃, and performing reaction according to the formula (n) of the cellulose polyether sodium: and n (ECH) is dropwise added into ECH according to the proportion of 1:3, after 1h of dropwise addition is finished, the mixture reacts for 2h at the temperature of 50 ℃, after the reaction is finished, the mixture is filtered, refined, and then excessive ECH is removed by distillation (the vacuum degree is controlled to be-0.09 MPa, the kettle temperature is lower than 130 ℃) to prepare the cellulose-based epoxy resin, wherein the epoxy value is 0.25eq/100g, and the viscosity is 2100mPa & s.
Example 4
Adding 30g of sodium cellulose and 120g of diethylene glycol dimethyl ether into a high-pressure reaction kettle, replacing with nitrogen for 3 times, starting a stirrer, slowly heating to 70 ℃, continuously introducing EO to 180g within 2 hours, controlling the reaction temperature to be 100 ℃, finishing EO addition, keeping the reaction pressure below 0.7MPa, and keeping the temperature for reaction for 1 hour, wherein the reaction pressure is not reduced any more; reducing the temperature to 30 ℃, releasing pressure and discharging to obtain a cellulose polyether sodium solution, and distilling to remove diethylene glycol dimethyl ether to obtain cellulose polyether sodium;
adding the cellulose polyether sodium into a four-neck flask provided with a reflux condenser tube, a thermometer and a constant-pressure dropping funnel, heating to 40 ℃, and performing reaction according to the formula (n) of the cellulose polyether sodium: and n (ECH) is dropwise added with ECH according to the proportion of 1:4, after 1h of dropwise addition is finished, the mixture reacts for 3h at the temperature of 50 ℃, after the reaction is finished, the mixture is filtered, refined, and then the excessive ECH is removed by distillation (the vacuum degree is controlled to be-0.09 MPa, the kettle temperature is lower than 130 ℃) to prepare the cellulose-based epoxy resin, wherein the epoxy value is 0.29eq/100g, and the viscosity is 1700 mPas.
Example 5
Adding 30g of sodium cellulose and 120g of toluene into a high-pressure reaction kettle, replacing 3 times with nitrogen, starting a stirrer, slowly heating to 70 ℃, continuously introducing EO to 180g within 3 hours, controlling the reaction temperature to be 100 ℃, after EO is added, keeping the reaction pressure to be lower than 0.7MPa, and keeping the temperature for reaction for 1 hour, wherein the reaction pressure is not reduced any more; reducing the temperature to 50 ℃, then decompressing and discharging to obtain a cellulose polyether sodium solution, and distilling to remove toluene to obtain cellulose polyether sodium;
adding the cellulose polyether sodium into a four-neck flask provided with a reflux condenser tube, a thermometer and a constant-pressure dropping funnel, heating to 40 ℃, and performing reaction according to the formula (n) of the cellulose polyether sodium: and n (ECH) is added into ECH dropwise according to the proportion of 1:7, after 2h of dropwise addition is finished, the mixture reacts for 2h at the temperature of 40 ℃, after the reaction is finished, the mixture is filtered, refined, and then excessive ECH is removed by distillation (the vacuum degree is controlled to be-0.09 MPa, the kettle temperature is lower than 130 ℃) to prepare the cellulose-based epoxy resin, wherein the epoxy value is 0.35eq/100g, and the viscosity is 1000 mPas.
Example 6
Adding 30g of sodium cellulose and 120g of diethoxymethane into a high-pressure reaction kettle, replacing 3 times with nitrogen, starting a stirrer, slowly heating to 70 ℃, continuously introducing PO to 180g within 2 hours, controlling the reaction temperature to be 100 ℃, keeping the reaction pressure to be lower than 0.7MPa after the PO addition is finished, and keeping the temperature for reaction for 1 hour, wherein the reaction pressure is not reduced any more; cooling to 30 ℃, then decompressing and discharging to obtain a cellulose polyether sodium solution, and distilling to remove diethoxymethane to obtain cellulose polyether sodium;
adding the cellulose polyether sodium into a four-neck flask provided with a reflux condenser tube, a thermometer and a constant-pressure dropping funnel, heating to 40 ℃, and performing reaction according to the formula (n) of the cellulose polyether sodium: and (n) (ECH) is dropwise added with ECH according to the proportion of 1:5, after 1h of dropwise addition is finished, the mixture reacts for 4h at the temperature of 40 ℃, after the reaction is finished, the mixture is filtered, refined, and then the excessive ECH is removed by distillation (the vacuum degree is controlled to be-0.09 MPa, the kettle temperature is lower than 130 ℃) to prepare the cellulose-based epoxy resin, wherein the epoxy value is 0.31eq/100g, and the viscosity is 1300 mPas.
Example 7
Adding 30g of sodium cellulose and 120g of toluene into a high-pressure reaction kettle, replacing 3 times with nitrogen, starting a stirrer, slowly heating to 70 ℃, continuously introducing PO to 180g within 2 hours, controlling the reaction temperature to be 100 ℃, keeping the reaction pressure to be lower than 0.7MPa after the PO is added, and keeping the temperature for reaction for 1 hour, wherein the reaction pressure is not reduced any more; reducing the temperature to 40 ℃, then decompressing and discharging to obtain a cellulose polyether sodium solution, and distilling to remove toluene to obtain cellulose polyether sodium;
adding the cellulose polyether sodium into a four-neck flask provided with a reflux condenser tube, a thermometer and a constant-pressure dropping funnel, heating to 40 ℃, and performing reaction according to the formula (n) of the cellulose polyether sodium: and n (ECH) is added into ECH dropwise according to the proportion of 1:8, after 1h of dropwise addition is finished, the mixture reacts for 3h at the temperature of 40 ℃, after the reaction is finished, the mixture is filtered, refined, and then excessive ECH is removed by distillation (the vacuum degree is controlled to be-0.09 MPa, the kettle temperature is lower than 130 ℃) to prepare the cellulose-based epoxy resin, wherein the epoxy value is 0.34eq/100g, and the viscosity is 1000mPa & s.
Test example 1
The infrared spectra of sodium cellulose, cellulose polyether sodium prepared in example 5, and cellulose polyether sodium prepared in example 7 are shown in fig. 1. In fig. 1, a is sodium cellulose, b is cellulose polyether sodium prepared in example 5, and c is cellulose polyether sodium prepared in example 7. As can be seen from FIG. 1, compared with sodium cellulose, the cellulose polyether sodium is 3413-3381 cm-1The absorption peak of hydroxyl group was reduced and was found to be 2938-2867cm-1The grafted modified polyether sodium has absorption peaks of methyl and methylene, does not appear in the raw material sodium cellulose, and is 1118-1059 cm-1The absorption peak of C-O-C is obviously enhanced, which proves that the grafting modification is successful.
Test example 2
The infrared spectrum of the cellulose-based epoxy resin prepared in example 5 is shown in fig. 2; the infrared spectrum of the cellulose-based epoxy resin prepared in example 7 is shown in fig. 3. As can be seen from FIGS. 2 and 3, the distance between 3413 cm and 3381cm is compared with that between b and c in FIG. 1-1The absorption peak of hydroxyl is reduced and is additionally 854cm-1And 908cm-1The characteristic absorption peak of epoxy group appears nearby, which proves that the epoxidation modification is successful, and the cellulose-based epoxy resin is prepared.
Application example 1
The cellulose-based epoxy resin prepared in example 5 is blended into E-51 epoxy resin, and then a theoretically required amount of diethylenetriamine curing agent is added for curing, wherein the curing conditions are as follows: the curing performance data are shown in Table 1 after overnight at room temperature, curing for 3h at 80 ℃ and aging for 7 days at room temperature. As can be seen from Table 1, the incorporation of the cellulose-based epoxy resin significantly improved the tensile strength, elongation at break and impact strength of the cured E-51 epoxy resin. Wherein, the cellulose-based epoxy resin with 10 percent of doping amount has the best impact resistance and toughness of a cured product.
TABLE 1 Performance results after incorporation of cellulose-based epoxy resins
Figure BDA0003301413780000101
Figure BDA0003301413780000111
Application example 2
The cellulose-based epoxy resin prepared in example 7 is blended into E-51 epoxy resin, and then a theoretically required amount of diethylenetriamine curing agent is added for curing, wherein the curing conditions are as follows: the curing performance data are shown in Table 2 after overnight at room temperature, curing for 3h at 80 ℃ and aging for 7 days at room temperature. As can be seen from Table 2, the incorporation of the cellulose-based epoxy resin improves the tensile strength, elongation at break and impact strength of the cured E-51 epoxy resin, wherein the improvement of the impact strength is particularly significant when the incorporation amount reaches 15%.
TABLE 2 Performance results after incorporation of cellulose-based epoxy resins
Figure BDA0003301413780000112
In tables 1 and 2, the method for calculating the incorporation amount of the cellulose-based epoxy resin is as follows: the cellulose-based epoxy resin accounts for the mass fraction of the bisphenol A epoxy resin.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A cellulose-based epoxy resin having a structure represented by formula I:
Figure FDA0003301413770000011
in the formula I, R1～R5Independently comprises H,
Figure FDA0003301413770000012
n、n1And n2Is the degree of polymerization; n is1Is 2 to 5; n is2Is 2 to 5.
2. The method for preparing the cellulose-based epoxy resin according to claim 1, comprising the steps of:
mixing sodium cellulose and an epoxy compound in an organic solvent, and carrying out ring-opening addition reaction to obtain liquid cellulose polyether sodium;
and mixing the liquid cellulose polyether sodium and epichlorohydrin, and carrying out epoxidation reaction to obtain the cellulose-based epoxy resin.
3. The production method according to claim 2, wherein the epoxy compound is one or both of ethylene oxide and propylene oxide.
4. The preparation method according to claim 2 or 3, wherein the mass ratio of the epoxy compound to the sodium cellulose is 5-10: 1.
5. The method according to claim 2, wherein the organic solvent comprises diethoxymethane, dipropoxymethane, dibutoxymethane, glyme, diglyme, toluene, xylene, or 1, 4-dioxane.
6. The preparation method according to claim 2 or 5, wherein the mass ratio of the organic solvent to the sodium cellulose is 3-20: 1.
7. The method according to claim 2, wherein the temperature of the ring-opening addition reaction is 70 to 130 ℃; the time of the ring-opening addition reaction is 2-8 h.
8. The preparation method of claim 2, wherein the molar ratio of the liquid cellulose polyether sodium to the epichlorohydrin is 1: 3-20.
9. The method according to claim 2 or 8, wherein the temperature of the epoxidation reaction is 30 to 80 ℃; the time of the epoxidation reaction is 1-6 h.
10. Use of the cellulose-based epoxy resin according to claim 1 or the cellulose-based epoxy resin prepared by the preparation method according to any one of claims 2 to 9 in toughening bisphenol a epoxy resin.
CN202111191738.7A 2021-10-13 2021-10-13 Cellulose-based epoxy resin and preparation method and application thereof Pending CN114015017A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108084402A (en) * 2017-12-15 2018-05-29 南京林业大学 A kind of hemicellulose base epoxy and preparation method thereof
JP2019210309A (en) * 2018-05-31 2019-12-12 公立大学法人兵庫県立大学 Production method of epoxidized cellulose
CN111116867A (en) * 2019-12-31 2020-05-08 南京林业大学 Tannin extract-based epoxy resin and preparation method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108084402A (en) * 2017-12-15 2018-05-29 南京林业大学 A kind of hemicellulose base epoxy and preparation method thereof
JP2019210309A (en) * 2018-05-31 2019-12-12 公立大学法人兵庫県立大学 Production method of epoxidized cellulose
CN111116867A (en) * 2019-12-31 2020-05-08 南京林业大学 Tannin extract-based epoxy resin and preparation method thereof

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