WO2019141140A1

WO2019141140A1 - Micro-nano lignocellulose, preparation method thereof and application thereof

Info

Publication number: WO2019141140A1
Application number: PCT/CN2019/071536
Authority: WO
Inventors: 张金柱; 王鹏辉; 张安; 唐地源; 刘顶
Original assignee: 济南圣泉集团股份有限公司
Priority date: 2018-01-19
Filing date: 2019-01-14
Publication date: 2019-07-25

Abstract

The present invention discloses a micro-nano lignocellulose, a preparation method thereof and an application thereof. The micro-nano lignocellulose comprises a lignin structure, in which the lignin is combined with cellulose in the form of a hydrogen bond and a chemical bond. The preparation method of the micro-nano lignocellulose is as follows. A lignin-containing cellulose raw material is dispersed in an organic solvent, a hot urea aqueous solution, or water at a temperature of at least 50 °C, so as to obtain a cellulose raw material dispersion liquid. Peeling and grinding are performed by means of mechanical pretreatment to obtain a pretreated product. The pretreated product is subjected to high-pressure homogenization by using a high-pressure homogenizer, thereby obtaining a micro-nano lignocellulose dispersion liquid.

Description

Micro-nano lignocellulose and preparation method and use thereof

Technical field

The present application belongs to the field of nano material preparation, and relates to a micro nano lignin cellulose, a preparation method and use thereof, and a micro nano cellulose composite, a preparation method and a use thereof.

Background technique

With the continuous development of the social economy, non-renewable resources such as petroleum and coal are becoming scarcer, and environmental pollution is becoming more and more prominent. The application of renewable resources in various fields is receiving more and more attention. Plant fiber raw materials are the most important biomass resources on the earth, and their efficient and comprehensive utilization will occupy an extremely important position in the entire biomass industry. Plant fibers are mainly composed of cellulose, lignin and hemicellulose. Cellulose is a widely existing and renewable resource on earth. Nanocellulose prepared from natural cellulose not only has a large specific surface area, high hydrophilicity, high Young's modulus, high strength, good biodegradability and biocompatibility, and stable chemical properties, but also has a huge The potential for chemical modification has shown great application prospects in the fields of papermaking, adsorbent materials, battery separators and high-performance composites.

Lignin is the second abundant renewable resource in the world. It mainly exists between cellulose fibers. It forms a woven network to harden the cell wall and acts as a compressive force. Lignin can be used as a dispersant, adsorbent, and enhancer, and has an extremely wide range of uses.

The common preparation methods of nanocellulose are chemical method, mechanical method, biological method and artificial synthesis method. Among them, the mechanical preparation of nanocellulose has little impact on the environment and the steps are simple, and is a preparation method suitable for large-scale commercial production. Since hard lignin is interwoven in the middle of cellulose, it is impossible to directly remove nanocellulose by mechanical stripping. At present, there is no method for preparing nanocellulose with high lignin content in the method for preparing nanocellulose. In the related art, it is still necessary to first pretreat plant fibers with acid, alkali or organic solvent to remove lignin and hemicellulose, and then perform mechanical stripping. The steps are cumbersome, and the acid, alkali or organic solvent used in the pretreatment process is still The environment causes certain pollution.

CN 101949103 A discloses a process for the preparation of micro-nanocellulose which is prepared directly from plant straws but which is still subjected to delignification treatment using a delignification reagent; CN 103194027 A discloses a nanocellulose/lignin The preparation method of the light-blocking film obtains the high-lignin content nano-cellulosic material, but in the preparation process, the lignin is removed to carry out the cellulose nano-treatment, and then the lignin is mixed with the nano-cellulose, and the preparation process is complicated and complicated. CN 104693464 A discloses a preparation method of a lignin nanocellulose-reinforced polylactic acid composite membrane, which adopts a sulfuric acid hydrolysis-high pressure homogenization method to prepare lignin nanocellulose, and sulfuric acid is used in the process, which has a great influence on the environment.

There is a need in the art to develop an environmentally and highly efficient preparation process that does not require delignification and can produce high nanolignin content micro-nanocellulose.

Graphene is a two-dimensional material of a honeycomb structure composed of a single layer of sp2 hybridized carbon atoms. Since its discovery in 2004, graphene has become a research hotspot in the scientific community. Graphene has a wide range of properties in battery materials, energy storage materials, electronic devices, composite materials, etc. due to its unique structure, high mechanical strength, excellent heat transfer and electrical conductivity, and large specific surface area. Application prospects.

Common preparation methods of graphene include mechanical peeling method, redox method and chemical deposition method. The mechanical peeling method is to use a friction between an object and a graphite sheet to peel off a graphene sheet from the surface of the graphite sheet. This method is simple and easy, but the method has a problem of low peeling efficiency and long time, and was once considered to be incapable of industrialization. Production, so it is necessary to add an intercalating agent to improve the peeling efficiency.

CN 102874797A discloses a method for producing high quality graphene on a large scale, using a soluble salt compound as a stripper and then obtaining a graphene by sonication. The method has mild preparation conditions, simple operation and easy realization of large-scale production. However, the soluble salt acts as a stripping agent and cannot effectively destroy the interaction between the graphene sheets, thereby affecting the stripping efficiency of graphene. CN 105523549 A discloses a stripping agent and a use for preparing graphene by mechanical stripping method, using 70-80% of polymeric organic matter, 5-15% of organic foaming agent and 10-20% of carrier as stripping agent, The mechanical exfoliation produces graphene, and the obtained graphene has high yield and small structural defects, and can significantly shorten the time for mechanical exfoliation to prepare graphene. However, the stripping agent used is not environmentally friendly, and the intercalation effect and the dispersing effect on graphene are not obvious.

Nanocellulose prepared from natural cellulose not only has a large specific surface area, high hydrophilicity, high Young's modulus, high strength, good biodegradability and biocompatibility, and stable chemical properties, but also has a huge The potential for chemical modification has shown great application prospects in the fields of papermaking, adsorbent materials, battery separators and high-performance composites.

The combination of graphene and nanocellulose in the field is expected to enhance the strength of the matrix material, but because of poor compatibility between the two and the organic substrate, it is easy to agglomerate in the organic substrate, and the dispersion is uneven, which in turn causes the strength of the substrate. decline.

There is a need in the art to develop a method for environmentally and efficiently preparing graphene and nano-scale cellulose composites, and the prepared product has good compatibility with an organic substrate.

Summary of the invention

The following is a summary of the subject matter described in detail herein, and is not intended to limit the scope of the claims.

The purpose of the present application includes providing a micro-nanolignin cellulose, a preparation method and use thereof, and a micro-nanocellulose composite comprising the same, a preparation method and use thereof.

In order to achieve the purpose of this application, the present application adopts the following technical solutions:

In a first aspect, the present application provides a micro-nanolignin cellulose, wherein the micro-nanolignin cellulose contains a lignin structure, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds.

In the present application, the lignin in the micro-nanolignin cellulose is combined with cellulose in the form of hydrogen bonds and chemical bonds, unlike the products produced by physical mixing of cellulose and lignin in the related art. The role of the bond, which leads to the inability of lignin to form a strong interaction with nanocellulose, reducing the application performance of micro-nanolignin cellulose.

In the present application, the "micro-nano lignocellulose" refers to a micro-nanocellulose containing a lignin structure; the micro-nanolignin cellulose is understood to contain 10-35 wt% lignin, and the diameter is Cellulose material within 1 nm - 1 μm.

Optionally, the content of lignin in the micro-nanolignin cellulose is 10-35 wt%, such as 10%, 15%, 18%, 21%, 22%, 23%, 24%, 25%, 26%. 27% or 28%, 30%, 32%, 35%, optional 25-28%.

Optionally, the micro-nanolignin cellulose has a diameter of 5-180 nm, such as 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm or 180 nm, and the aspect ratio ≥ 200, for example, may be 200, 210, 220, 240, 260, 280, 300, 320, 340, 360, 380, and the like.

The micro-nanolignin cellulose defined in the present application has a diameter of D90, that is, 90% of the micro-nanolignin cellulose has a diameter below the D90 diameter.

In a second aspect, the present application provides a method of preparing micro-nanolignin cellulose as described above, the method comprising the steps of:

(1) adding a cellulose raw material containing lignin to an organic solvent, a hot aqueous urea solution or any solvent in water at 50 ° C or higher to obtain a raw material dispersion;

(2) the raw material dispersion obtained in the step (1) is subjected to mechanical pretreatment for peeling and grinding to obtain a pretreated product;

(3) The pretreated product obtained in the step (2) is subjected to high pressure homogenization using a high pressure homogenizer to obtain a dispersion of the micro nano lignin cellulose.

In the present application, it is not necessary to carry out delignification treatment on the lignin-containing cellulose raw material, and the hot urea aqueous solution is used to soften the lignin on the one hand, and the urea weakens the hydrogen bonding between the lignin and weakens the lignin on the other hand. The π-π conjugate of the benzene ring in the structure, thereby reducing the hardness of lignin and destroying the adhesion of lignin to cellulose, but urea does not cause chemical damage to lignin, and can be combined with mechanical pretreatment and high pressure. In the case of a qualitative means, a micro-nanocellulose having a high lignin content, that is, a micro-nanolignin cellulose, is prepared.

Or using an organic solvent, retaining lignin as a natural dispersant, which enhances the interaction of micro-nanocellulose with an organic solvent, and in combination with mechanical pretreatment and high-pressure homogenization means, first breaks the cellulose raw material into cellulose particles, and then first breaks the cellulose raw material into cellulose particles, and then The crushed cellulose particles are placed in a high-pressure homogenizer, and the cellulose particles are peeled off to obtain a micro-nano lignocellulose organic dispersion, so that the micro-nano lignocellulose organic dispersion is stable and does not precipitate.

Or it is only necessary to disperse the cellulose raw material containing lignin in water above 50 ° C, soften the lignin contained therein, and weaken the hydrogen bonding between the raw material lignin, and weaken the π-π of the benzene ring in the lignin structure. Conjugation, thereby reducing the hardness of lignin, destroying the adhesion of lignin to cellulose, combined with subsequent mechanical pretreatment and high-pressure homogenization, can achieve the detachment of lignin-containing cellulose raw materials, and obtain high lignin The content of micro-nanocellulose, namely micro-nano lignocellulose. If the water temperature of the step (1) of the method is lower than 50 ° C, the hardness of the lignin is large, and it is difficult to weaken the interaction between the lignin and the lignin and the cellulose, and it is difficult to carry out subsequent treatment of the raw material.

The preparation method of the micro-nanolignin cellulose of the present application solves the problems that the plant fiber raw material needs to be subjected to delignification pretreatment, low concentration, high energy consumption, easy clogging of the homogenization process and discontinuous preparation process in the related art. Moreover, the present application provides a mechanical pretreatment step prior to high pressure homogenization, which can effectively reduce the size of the cellulose particles, ensure that the high pressure homogenizer is not blocked during the high pressure homogenization process, and reduce the wear on the high pressure homogenizer.

In the step (1), optionally, the lignin-containing cellulose raw material in the preparation method of the micro-nano lignocellulose of the present application is a residue obtained by completely extracting hemicellulose or partially extracting hemicellulose from a plant material. .

Optionally, the plant material comprises any one of forest, crop, agricultural and forestry waste, or a combination of at least two.

Optionally, the lignin-containing cellulosic material comprises any one or a combination of at least two of furfural residue, xylose residue, unbleached wood pulp, unbleached straw pulp, and straw agricultural waste.

In the present application, optionally, the lignin-containing cellulose raw material has a lignin content of 10-30% by weight, such as 10% by weight, 12% by weight, 15% by weight, 18% by weight, 20% by weight, 22% by weight, 24% by weight, 26 wt%, 28 wt% or 30 wt%, and the like.

Optionally, the lignin-containing cellulosic feedstock has a cellulose content of 65 wt% or more, such as 65 wt%, 68 wt%, 70 wt%, 73 wt%, 75 wt%, 78 wt%, 80 wt%, and the like.

Optionally, the lignin-containing cellulosic material further comprises hemicellulose.

Optionally, the lignin-containing cellulosic feedstock has a hemicellulose content of ≤ 10 wt%, such as 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt% or 1wt%, etc.

When the solvent of the step (1) is an aqueous urea solution, optionally, the temperature of the aqueous urea solution is 72 ° C or more and less than 100 ° C, for example, 72 ° C, 74 ° C, 76 ° C, 78 ° C, 80 ° C, 82 ° C, 85 ° C, 88 ° C, 90 ° C, 93 ° C, 95 ° C, 98 ° C or 99 ° C, optional 80-90 ° C.

In the present application, a hot aqueous urea solution is used to overcome the influence of the presence of lignin on the formation of smaller diameter nanocellulose, if the temperature is too low, it will affect the formation of nanocellulose; Too high, for example above 100 ° C, the water will boil, affecting subsequent stripping, grinding, and high pressure homogenization processes, making subsequent processes inoperable.

Optionally, the concentration of the aqueous urea solution is 0.1-10 mol/L, for example, 0.1 mol/L, 0.5 mol/L, 0.8 mol/L, 1 mol/L, 1.3 mol/L, 1.5 mol/L, 2 mol/L. 2.5 mol/L, 3 mol/L, 3.5 mol/L, 4 mol/L, 5 mol/L, 6 mol/L, 7 mol/L, 8 mol/L, 9 mol/L, 9.5 mol/L or 10 mol/L.

Optionally, the concentration of the lignin-containing cellulose raw material in the raw material dispersion is 1 wt% to 10 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt% 9 wt% or 10 wt%, optionally 5 wt%.

In the present application, the lignin and the cellulose in the micro-nano lignocellulose dispersion are combined by hydrogen bonding and chemical bonding, and are suspended and dispersed in an aqueous solution.

When the solvent of the step (1) is an organic solvent, the organic solvent is optionally an organic solvent having a boiling point higher than 72 °C.

Optionally, the organic solvent is ethanol, isopropanol, n-butanol, tert-butanol, butanone, formamide, acetamide, N,N-dimethylformamide, N,N-dimethyl B. Any one or at least two of amide, aniline, benzene, toluene, xylene, chlorobenzene, octane, dimethyl sulfoxide, dioxane, ethyl acetate, acetonitrile, pyridine or carbon tetrachloride combination.

Optionally, the organic solvent is heated to 72-128 ° C, such as 72 ° C, 74 ° C, 76 ° C, 78 ° C, 80 ° C, 85 ° C, 88 ° C, before adding the lignin-containing cellulose raw material to the organic solvent. 90 ° C, 95 ° C, 100 ° C, 105 ° C, 110 ° C, 120 ° C or 125 ° C, and the like.

Alternatively, the heating temperature is not higher than the boiling point of the organic solvent.

If the heating temperature of the organic solvent is too low, it will affect the formation of micro-nanolignin cellulose, and if the heating temperature is too high, for example, higher than the boiling point of the organic solvent, the organic solvent will boil, which will affect the subsequent peeling and grinding. And the high pressure homogenization process, making these subsequent mechanical stripping processes inoperable.

Optionally, the content of the lignin-containing cellulose raw material in the raw material dispersion in the step (1) is 1-20 wt%, for example, 1 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt%. 16 wt%, 18 wt% or 20 wt%, optionally 3-10 wt%.

When the solvent of the step (1) is water above 50 ° C, optionally, the temperature of the water in the step (1) is ≥ 70 ° C (for example, 72 ° C, 76 ° C, 78 ° C, 85 ° C, 88 ° C, 92 ° C, etc.) The temperature of the water may be selected to be below the boiling point of water, optionally 70 to 80 ° C, optionally 70 to 75 ° C.

If the temperature of the water is too high (such as above 90 °C), it will destroy the chemical structure of the lignin itself, freeing the lignin from the cellulose and reducing the lignin content in the micro-nano lignocellulose.

It should be understood by those skilled in the art that water above 90 ° C does not mean that water above 90 ° C cannot be used in the present application, but wood in the prepared micro-nano lignocellulose when the water temperature is higher than 90 ° C. The content of the hormone has decreased. When the lignin content is 38%, when the water temperature is higher than 90 ° C, the lignin content in the prepared micro-nano lignocellulose is about 10 to 15 wt%; When the water temperature is between 50 and 90 ° C, the lignin content in the prepared micro-nano lignocellulose is 13 to 37 wt%; and when the water temperature is between 60 and 80 ° C, the prepared micro-nano lignocellulose The lignin content in the range is 20 to 37% by weight.

Optionally, the concentration of the lignin-containing cellulose raw material in the raw material dispersion is 0.08-18 wt%, for example, 0.1 wt%, 0.4 wt%, 0.8 wt%, 1.5 wt%, 2.8 wt%, 6 wt%, 8 wt%, 11 wt%, 14 wt%, 17 wt%, etc., optionally 5-8 wt%.

In the step (2), optionally, the mechanical pretreatment comprises one or a combination of at least two of ball milling, disc grinding or sanding, optionally sanding.

Optionally, the number of cycles of the mechanical pretreatment is greater than or equal to one, for example, 2, 3, 4, 5, 6, 7, 8, 11, 15, 15, or 18 times. 20 times.

In the present application, the manner of mechanical pretreatment and the number of cycles can be appropriately selected depending on the size of the desired product.

Alternatively, when sanding is used, the number of cycles of the sand mill is 1-3 times, and the diameter of the sanded product is 200-1000 nm, for example, 220 nm, 250 nm, 280 nm, 300 nm, 320 nm, 350 nm, 380 nm, 400 nm, 450 nm. 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, etc.; the number of cycles of the sand mill is ≥ 5 times, and the diameter of the sanded product is 100-200 nm, for example, 120 nm, 140 nm, 160 nm, 180 nm, and the like.

Alternatively, when ball milling and/or disc grinding is employed, the number of cycles is greater than or equal to 10 times, for example, 11 times, 13 times, 14 times, 15 times, 16 times, 18 times, 20 times, and the like.

Optionally, when the solvent in the step (1) is a hot aqueous urea solution, when the raw material dispersion obtained in the step (1) is peeled and ground by mechanical pretreatment, the temperature of the raw material dispersion is maintained at 72 or more. °C and less than 100 °C.

Optionally, when the solvent in the step (1) is an organic solvent, when the raw material dispersion obtained in the step (1) is peeled and ground by mechanical pretreatment, the temperature of the raw material dispersion is kept not higher than the above. The boiling point of the organic solvent in the raw material dispersion.

Optionally, when the solvent in the step (1) is water above 50 ° C, the raw material dispersion obtained in the step (1) is subjected to mechanical pretreatment for peeling and grinding, and the temperature of the raw material dispersion is maintained at 70. -80 ° C, for example, 70 ° C, 72 ° C, 75 ° C, 77 ° C, 78 ° C, 79 ° C, and the like.

Maintaining the temperature of the raw material dispersion during the mechanical pretreatment can soften the lignin while mechanically peeling off, and improve the yield of the micro-nanolignin cellulose.

In the step (3), optionally, the high pressure homogenization pressure is 50-150 MPa, for example, 60 MPa, 65 MPa, 70 MPa, 75 MPa, 80 MPa, 90 MPa, 110 MPa, 120 MPa, 140 MPa, etc., optionally 60-80 MPa.

Alternatively, the number of cycles of the high pressure homogenization is 3-7 times, for example 4 times, 5 times, 6 times or 7 times.

Optionally, when the solvent in the step (1) is a hot aqueous urea solution, the temperature during the high pressure homogenization is maintained at a temperature of 72 ° C or more and less than 100 ° C.

Optionally, when the solvent in the step (1) is an organic solvent, the high pressure homogenization process maintains the temperature not higher than the boiling point of the organic solvent in the pretreatment product obtained in the step (2).

Optionally, when the solvent in the step (1) is water above 50 ° C, the temperature during the high pressure homogenization is maintained at 70-80 ° C, for example, 70 ° C, 72 ° C, 75 ° C, 77 ° C, 78. °C, 79 °C, etc.

The high temperature homogenization process maintains the temperature of the raw material dispersion liquid to soften the lignin while mechanically peeling off, and improves the yield of the micro-nano lignocellulose.

When the solvent in the step (1) is an organic solvent, optionally, the micro-nano lignocellulose in the micro-nano lignocellulose dispersion obtained in the step (3) has a diameter of 5 to 250 nm (for example, 5 nm, 8 nm, 10 nm). 20 nm, 50 nm, 80 nm, 100 nm, 130 nm, 150 nm, 180 nm, 200 nm, 220 nm or 240 nm), the length is more than 2 μm (for example, 2 μm, 3 μm, 5 μm, 8 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm or 50 μm, etc.). Optionally, the content of the micro-nano lignocellulose in the micro-nano lignocellulose dispersion is 0.1%-18%, such as 0.1%, 0.5%, 0.8%, 1.0%, 1.5%, 3%, 5 %, 8%, 10%, 12%, 16%, 18%, etc.

Optionally, when the solvent in the step (1) is water above 50 ° C, optionally, the micro-nanolignin cellulose has a diameter of 20 to 800 nm, for example, 25 nm, 30 nm, 50 nm, 80 nm, 100 nm, 120 nm. , 140 nm, 160 nm, 180 nm, 200 nm, 250 nm, 300 nm, 400 nm, 450 nm, 500 nm, 600 nm, 650 nm, 700 nm or 750, etc., the aspect ratio is ≥ 50, and the optional micro-nano lignocellulose has a diameter of 20 to 200 nm, for example, 25 nm. 30 nm, 50 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm or 180 nm, etc., the aspect ratio is ≥200.

In the present application, the content of micro-nanocellulose in the micro-nano lignocellulose dispersion refers to the total mass percentage of micro-nanocellulose containing lignin in the dispersion, and the content of lignin refers to lignin The percentage content of the total mass of the nanolignin cellulose is the percentage content of the solid content of the micro-nanolignin cellulose in the micro-nano lignocellulose dispersion.

Optionally, after step (3), step (4) is carried out: removing the solvent of the dispersion of the micro-nano lignocellulose to obtain micro-nanolignin cellulose.

Alternatively, the method of "removing a solvent of the dispersion of the micro-nanolignin cellulose to obtain micro-nanolignin cellulose" includes any one or a combination of at least two of filtration, centrifugation, and drying.

Optionally, the method of “removing the solvent of the dispersion of the micro-nano lignocellulose to obtain micro-nano lignocellulose” is carried out by filtration or centrifugation, and then the filter residue is dried to obtain micro-nanolignin fiber. Prime.

Optionally, the drying comprises any one or a combination of at least two of spray drying, freeze drying and supercritical drying.

Alternatively, the micro-nano lignocellulose dispersion is post-treated to obtain a micro-nano lignocellulose dispersion, a micro-nanolignin cellulose powder or a micro-nano lignocellulose film.

Optionally, the post treatment comprises any one or a combination of at least two of filtration, washing, spray drying, and coating film formation.

In the present application, the micro-nano lignocellulose dispersion can be post-treated to prepare micro-nano lignocellulose powder, for example, by filtering, washing and spray-drying the micro-nano lignocellulose dispersion into a powder; The micro-nano lignocellulose dispersion is post-treated to prepare a micro-nano lignocellulose film, for example, filtered, washed, coated to form a film, or the micro-nano lignocellulose dispersion prepared by the step (3) can be prepared. After filtration and washing, the micro-nano lignocellulose dispersion is directly applied.

The preparation method described in the present application reduces the pretreatment process of the cellulose raw material, reduces the use of a large amount of chemical reagents, reduces environmental pollution, eliminates the need to remove lignin, and realizes micro-nano fibers having good performance under high lignin content. Prime. When an organic solvent is used, the high content of lignin contained in the micro-nano lignocellulose dispersion is combined with cellulose by hydrogen bonding and chemical bonding, suspended and dispersed in a solution, and micro-nanolignin is dispersed by means of lignin dispersion. The cellulose organic dispersion has good dispersibility and effectively improves the performance of the micro-nano lignocellulose, thereby realizing the micro-nanocellulose organic dispersion with good dispersibility under high lignin content, and solving the current lignin. The problem of dispersion of nanocellulose in organic solvents cannot be solved without the use of other dispersants. When water above 50 °C is used, most of the lignin (about 80% or more) in the micro-nanolignin cellulose is bound to cellulose in the form of a covalent bond. A chemical bond can be interpreted as "a general term for a strong interaction force between two or more atoms (or ions) within a pure molecule or within a crystal." The force that binds ions or combines atoms is commonly referred to as a chemical bond. Chemical bonds include ionic bonds, covalent bonds, and metal bonds, excluding hydrogen bonds.

The application uses hot water to soften lignin, urea weakens the hydrogen bonding function of lignin and cellulose, reduces the hardness of lignin, destroys the adhesion of lignin to cellulose, and makes high lignin cellulose raw materials (such as agricultural waste materials) It is possible to directly prepare micro-nanocellulose.

In a third aspect, the application provides the use of micro-nano lignocellulose as described above for textile materials, medical materials, high performance auxiliaries, adsorbent materials, food packaging materials or composites Preparation of materials.

In a fourth aspect, the present application provides a micro-nanocellulose composite comprising the micro-nanolignin cellulose of the first aspect, and dispersed in the micro-nanolignin cellulose Graphene material.

Optionally, the content of the graphene material is 15 wt% or less (for example, 10 wt%, 8 wt%, 5 wt%, 2 wt%, 1 wt%, etc.) of the micro-nanolignin cellulose, optionally 5 wt% or less, and optionally 1 wt. %the following.

Optionally, the graphene material has a thickness of ≤20 nm (eg, 18 nm, 15 nm, 12 nm, 8 nm, 5 nm, etc.), optionally 3 to 10 nm.

Optionally, the micro-nanocellulose composite has a length of ≥1 μm (eg, 1.1 μm, 2 μm, 3 μm, 5 μm, 7 μm, etc.) and a diameter of 4 to 200 nm (eg, 10 nm, 50 nm, 80 nm, 150 nm, 180 nm, etc.), The aspect ratio is 100 to 500 (for example, 120, 180, 220, 270, 300, 350, 380, 420, 480, etc.).

In a fifth aspect, the present application provides a method for preparing the micro-nanocellulose composite, the method comprising the following steps:

(I) dispersing the cellulose raw material containing lignin and the graphene material in water, and uniformly mixing to obtain a dispersion;

(II) pre-stripping the dispersion by mechanical force to obtain a pre-separation product dispersion;

(III) The pre-stripped product dispersion is homogenized by a high-pressure homogenizer to obtain a micro-nanocellulose composite dispersion.

The method adopts a combination of mechanical pre-peeling and high-pressure homogenizer to prepare the micro-nanocellulose composite, which can avoid the clogging of the high-pressure homogenizer directly in the crushing process and reduce wear.

Optionally, the plant material comprises any one or a combination of at least two of forest trees, crops, and agricultural and forestry wastes;

Optionally, the lignin-containing cellulose raw material has a lignin content of 10 to 30 wt% (for example, 15 wt%, 20 wt%, 25 wt%, etc.), and the cellulose content of the xylose residue is 65% or more. (eg 70 wt%, 75 wt%, 80 wt%, etc.).

Optionally, the lignin-containing cellulose raw material has a hemicellulose content of ≤10 wt% (for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%) , 10wt%, etc.).

In the related art, in the preparation process of nanocellulose, the raw material needs to be bleached, and the so-called bleaching treatment requires removal of lignin in the raw material by using a strong acid, a strong alkali or an organic solvent. The preparation method of the micro-nanocellulose composite provided by the present application utilizes a graphene material intercalation of a lignin-containing cellulose raw material, and realizes lignin only by mechanical force without using a strong acid, a strong alkali and an organic solvent. The exfoliation of the higher content of the cellulose raw material obtains the micro-nanocellulose composite, which is environmentally friendly and non-polluting.

The graphene material is prepared by a mechanical stripping method, a redox method, a thermal cracking method, an intercalation stripping method, a chemical vapor deposition method, a liquid phase stripping method, or a biomass hydrothermal carbonization method.

Optionally, the graphene material has an average sheet thickness of ≤20 nm (eg, 18 nm, 14 nm, 10 nm, 5 nm, 2 nm, etc.), optionally 3-10 nm.

The graphene material having a thickness of 3 to 10 nm is more favorable for intercalation into the interior of the lignin molecule, thereby achieving the peeling of the micro-nanocellulose composite.

Optionally, the sum of the concentrations of the lignin-containing cellulose raw material and the graphene material in the dispersion is 0.1 wt% to 15 wt% (for example, 1 wt%, 3 wt%, 6 wt%, 7 wt%, 9 wt%, 12 wt%) %, etc.), optionally 5wt%-7wt%.

Optionally, the graphene material is added in an amount of 10 wt% or less of the lignin-containing cellulose raw material (for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9wt%, etc.), optionally 5wt% or less, optionally 1wt% or less.

Optionally, the mechanical force pre-peeling comprises any one of ultrasonic peeling, ball peeling, disc peeling, sanding peeling, and grinding peeling.

Optionally, the mechanically pre-exfoliated product has a diameter of 200 to 1500 nm (eg, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm). , 1400nm, etc.).

Optionally, the homogeneous pressure in the step (3) is 50-150 MPa (for example, 70 MPa, 90 MPa, 110 MPa, 120 MPa, 140 MPa, etc.), and optionally 60-80 MPa.

Optionally, the number of times of homogenization is 3 to 10 times (for example, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, etc.), and may be selected 3 to 7 times.

Optionally, after step (3), step (4) is carried out: the micro-nanocellulose composite dispersion is post-treated to obtain a micro-nanocellulose composite powder.

Optionally, the post treatment comprises any one or a combination of at least two of washing, grinding, and spray drying.

In a sixth aspect, the present application provides another method for preparing a micro-nanocellulose composite according to the fourth aspect, the method comprising the steps of:

(a) adding a graphite raw material and a cellulose raw material containing lignin to the aqueous urea solution to obtain a mixed raw material dispersion;

(b) mechanically separating the mixed raw material dispersion to obtain a micro-nanocellulose composite dispersion;

Alternatively, the solvent of the micro-nanocellulose composite dispersion is removed to obtain a micro-nanocellulose composite.

In this method, urea can be initially stripped of graphite and/or lignin-containing cellulose raw material to obtain a small amount of graphene and/or micro-nanolignin cellulose, followed by stripping of graphene and/or micro-nanolignin. Cellulose can continue to strip the raw material as an intercalating agent. For example, the stripped graphene can peel off the cellulose raw material containing lignin to obtain micro-nano lignocellulose, and the stripped micro-nano lignocellulose can peel off the graphite raw material. A graphene is obtained.

In this method, urea acts as an auxiliary stripping effect, and subsequent graphene acts as an intercalating agent to strip the cellulose raw material containing lignin, and the micro-nano lignocellulose further serves as an intercalating agent to strip the graphite raw material.

Optionally, in the aqueous urea solution, the ratio of the mass of the urea to the mass of the graphite raw material and the lignin-containing cellulose raw material is ≤1:3, for example, 0.8:3, 0.7:3, 0.6:3, 0.5:3, 0.4:3, 0.3:3, 0.2:3, 0.1:3, 0.08:3, 0.05:3, 0.03:3, 0.02:3, 0.01:3, 0.008:3, etc., optional 0.01:1 to 1:1 .

In this method, urea only serves to assist the peeling, and the amount of addition is lower than that of urea in the related art as the main stripper.

Optionally, the aqueous urea solution has a temperature of 72 to 100 ° C, for example, 75 ° C, 80 ° C, 85 ° C, 90 ° C, 95 ° C, etc., optionally 80 to 90 ° C.

In the lignin-containing cellulose raw material, the lignin existing between the cellulose firmly binds the cellulose together, and is not easily peeled off to obtain the micro-nano lignocellulose, and the higher temperature aqueous urea solution can soften the wood. It reduces the binding force between lignin and cellulose and improves the peeling efficiency of micro-nano lignocellulose.

Optionally, in the mixed raw material dispersion, the sum of the concentrations of the graphite raw material and the lignin-containing cellulose raw material is 0.1 to 20 wt%, for example, 0.2 wt%, 0.5 wt%, 0.8 wt%, 2 wt%, 5 wt%. 8 wt%, 9 wt%, 12 wt%, 15 wt%, 18 wt%, etc., optionally 8 to 10 wt%.

Optionally, the mass ratio of the graphite raw material to the lignin-containing cellulose raw material is 1:10 to 10:1, for example, 2:10, 3:10, 4:10, 5:10, 6:10, 7 :10, 8:10, 9:10, 10:10, 10:9, 10:8, 10:7, 10:6, 10:5, 10:4, 10:3, 10:2, 10:1 Wait.

Optionally, the lignin-containing cellulosic material is a residue obtained by completely extracting hemicellulose or partially extracting hemicellulose from a plant material.

Optionally, the plant material comprises any one or a combination of at least two of forest trees, crops, and agricultural and forestry waste.

Optionally, the lignin-containing cellulose raw material has a lignin content of 10 to 30% by weight, for example, 12% by weight, 15% by weight, 17% by weight, 20% by weight, 23% by weight, 25% by weight, 28% by weight, etc., and cellulose The content is above 65%.

Optionally, the lignin-containing cellulose raw material has a hemicellulose content of ≤10 wt%, for example, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%. Wait.

Optionally, the graphite raw material comprises any one or a combination of at least two of expanded graphite, flake graphite, and graphite oxide.

Optionally, the mechanical peeling comprises any one or a combination of at least two of ultrasonic peeling, ball peeling, disc peeling, sanding peeling, high pressure homogenizing peeling, high pressure micro jet stripping, and grinding stripping.

Illustratively, the ultrasonic stripping power is 100-1500 kW, the ultrasonic time is 10-90 minutes; the high pressure homogenizing stripping pressure is 30-150 MPa, and the high pressure homogenizing is 3-30 cycles; the high-pressure micro jet stripping The pressure is 150-300 MPa, and the peeling is 3-20 cycles.

Alternatively, the method of "removing the solvent of the micro-nanocellulose composite dispersion" includes any one or a combination of at least two of filtration, centrifugation, and drying.

Alternatively, the method of “removing the solvent of the micro-nanocellulose composite dispersion” is followed by filtration separation or centrifugation, and the filter residue is dried to obtain a micro-nanocellulose composite.

Optionally, the micro-nanocellulose composite prepared by the method has a diameter of 5 to 180 nm and an aspect ratio of ≥200; and the graphene material has a particle diameter of 0.1 to 50 μm.

In a seventh aspect, the present application provides the use of the micro-nanocellulose composite according to the fourth aspect, wherein the micro-nanocellulose composite is used in the textile field, the medical field, the high-performance auxiliary field, the adsorption material field, In the field of food packaging or composite materials, for example, the micro-nanocellulose composites are used in the preparation of textile materials, medical materials, high performance auxiliaries, adsorbent materials, food packaging materials or composite materials.

Compared with related technologies, the present application has the following beneficial effects:

(1) The lignin in the micro-nanolignin cellulose of the present application is bonded to cellulose in the form of hydrogen bonds and chemical bonds, and the cellulose has a diameter of 5-180 nm and an aspect ratio of ≥200, wherein the lignin content is 10-35 wt%. It can effectively improve the performance of micro-nanocellulose, and can be made into aqueous slurry, dried into powder or made into film material, and has a wide application range.

(2) This application uses organic solvent, hot urea aqueous solution or any solvent in water above 50 °C to soften lignin. Urea weakens the hydrogen bonding of lignin and cellulose, reduces the hardness of lignin, and destroys lignin to fiber. The binding of the pigment makes it possible to prepare the micro-nano lignocellulose directly from the high lignocellulose raw material (for example, agricultural waste raw materials).

(3) Preparation of micro-nano lignin cellulose by mechanical separation, urea solution can be recycled and recycled, avoiding the use of various strong acids, alkalis and organic solvents, environmental protection and pollution-free; high production efficiency, strong continuity, low cost, products The fineness is high, and the fineness of the product can be adjusted by adding or subtracting the grinding medium; the micro-nano lignin cellulose is prepared by the combination of mechanical pretreatment and high-pressure homogenizer, which can avoid the blockage of the high-pressure homogenizer in the crushing process. Reduce wear and tear.

(4) The present application utilizes the thin layer characteristics of the graphene material to mix it with the lignin-containing cellulose raw material, and the graphene material is intercalated into the lignin-containing cellulose raw material, and the lignin is stripped to obtain the micro-nano wood. Cellulose, the process does not require chemical reagents, the operation is simple and easy to control; graphene acts as an intercalation layer, and it is not necessary to pretreat the cellulose raw material containing lignin to the lignin, and then directly peel off to obtain micro-nano Cellulose composite, environmentally friendly and non-polluting;

(5) The present application uses urea to assist the stripping of the graphite material and the cellulose raw material containing lignin, and then further strips the remaining raw materials by using the stripped material, without using other chemical intercalating agents, environmentally friendly and easy to operate; The micro-nanocellulose composite exhibits good dispersibility in a non-aqueous solvent and improves the compatibility of the micro-nanocellulose composite with the polymer material.

Other aspects will be apparent upon reading and understanding the detailed description and drawings.

DRAWINGS

Figure 1 is a transmission electron micrograph of the micro-nanolignin cellulose of Example 1-1 of the present application, the scale of which is 500 nm;

2 is a transmission electron micrograph of the micro-nano lignocellulose dispersion prepared in Example 3-1 of the present application, the scale of which is 2 μm;

3 is a transmission electron micrograph of the micro-nano lignocellulose dispersion prepared in Example 3-2 of the present application, the scale of which is 2 μm.

Detailed ways

The technical solutions of the present application are further described below by way of specific embodiments. It should be understood by those skilled in the art that the present invention is only to be understood as an understanding of the present application and should not be construed as a limitation.

In the present application, lignin, fiber contained in residues such as furfural residue, xylose residue, unbleached wood pulp, unbleached straw pulp, and straw agricultural waste obtained after extracting hemicellulose or partial hemicellulose from plant raw materials The contents of the pigments and hemicelluloses are similar, so the following examples use xylose slag as an example to prepare micro-nano lignocellulosic products or composites thereof.

Example 1-1

In the present embodiment, the micro-nano lignocellulose has a lignin content of 22%, a cellulose diameter of 110 nm, and an aspect ratio of 212, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds.

The preparation method specifically comprises the following steps:

(1) Weigh 10g xylose residue (lignin 25wt%, cellulose 70wt%, hemicellulose 5wt%) dissolved in 490mL 5mol / L urea aqueous solution heated to 72 ° C and stirred to obtain xylose residue raw material dispersion;

(2) The xylose residue raw material dispersion obtained in the step (1) is placed in a sand mill, and the slurry is pulverized once while maintaining the temperature of the raw material dispersion liquid at 72 ° C to obtain a peeled product having a diameter of about 500 nm;

(3) The peeled product prepared in the step (2) is transferred to a high-pressure homogenizer, and the high-pressure crushing is performed 7 times under the pressure of 100 MPa while maintaining the solution temperature at 72 ° C.

FIG. 1 is a TEM image obtained by using a JEM-1200EX (120KV) type transmission electron microscope test for the micro-nanolignin cellulose prepared in the present embodiment. It can be seen from the figure that the cellulose is effectively stripped to the nanometer scale, and the aspect ratio is high, and the layers are connected to each other to form a network structure, and the lignin is combined with the cellulose to adhere to the surface of the nanocellulose.

Example 1-2

In the present embodiment, the micro-nano lignocellulose has a lignin content of 25%, a cellulose diameter of 69 nm, and an aspect ratio of 351, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds. The preparation method is similar to that of Example 1-1 except that the temperatures of the steps (1)-(3) of the present embodiment are both 80 ° C instead of 70 ° C; the pressure of the step (3) is 100 MPa instead of 60 MPa.

Examples 1-3

In this embodiment, the micro-nano lignocellulose has a lignin content of 28%, a cellulose diameter of 88 nm, and an aspect ratio of 298, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds. The preparation method is similar to that of the embodiment 1-1 except that the xylose residue composition is 28 wt% lignin and 72 wt% cellulose in the embodiment, and the temperatures of the steps (1)-(3) are both 80 ° C instead of 70. °C; Step (2) to obtain a peeling material having a diameter of about 400 nm, and the number of high-pressure crushing in step (3) is three times.

Examples 1-4

In the present embodiment, the micro-nano lignocellulose has a lignin content of 22%, a cellulose diameter of 170 nm, and an aspect ratio of 205, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds. The preparation method is similar to that of the embodiment 1-1 except that the composition of the xylose residue in the embodiment is 20 wt% lignin, 75 wt% cellulose and 5 wt% hemicellulose; the step (2) the number of ball milling is 10 times, A stripper having a diameter of about 800 nm; and a pressure of step (3) of 50 MPa.

Examples 1-5

In the present embodiment, the micro-nanolignin cellulose has a lignin content of 27%, a cellulose diameter of 30 nm, and an aspect ratio of 355, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds. The preparation method is similar to that of the embodiment 1-1 except that the composition of the xylose residue of the present embodiment is 30 wt% lignin and 70 wt% cellulose; the aqueous urea solution is 1 mol/L; the temperatures of the steps (1)-(3) are both It is 90 ° C; the step (2) is cycled 5 times to obtain a peeling material having a diameter of about 150 nm; and the step (3) is a pressure of 80 MPa.

Example 1-6

In the present embodiment, the micro-nano lignocellulose has a lignin content of 26%, a cellulose diameter of 120 nm, and an aspect ratio of 262, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds.

The preparation method specifically comprises the following steps:

(1) Weigh 10 g of xylose residue (in which 28% by weight of lignin in xylose residue, 70% by weight of cellulose, 2% by weight of hemicellulose) is dissolved in 324 mL of 3 mol/L urea aqueous solution, and heated to 80 ° C to stir evenly. Obtaining a raw material dispersion of xylose residue;

(2) The xylose residue raw material dispersion obtained in the step (1) is placed in a disc grinder, and the disc is subjected to a circular grinding 15 times while maintaining the temperature of the dispersion liquid at 80 ° C to obtain a peeling material having a diameter of 500 to 600 nm;

(3) The peeled product prepared in the step (2) is transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out 4 times under the condition of maintaining the temperature of the solution at 80 ° C under a pressure of 100 MPa.

Example 1-7

In this embodiment, the micro-nano lignocellulose has a lignin content of 22%, a cellulose diameter of 6 nm, and an aspect ratio of 400, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds.

The preparation method specifically comprises the following steps:

(1) Weigh 10g xylose residue (in which the lignin in the xylose residue is 25wt%, the cellulose content is 65wt%, and the hemicellulose is 10wt%) dissolved in 90mL 8mol/L urea aqueous solution, heated to 95 ° C and stirred evenly. Obtaining a raw material dispersion of xylose residue;

(2) The xylose residue raw material dispersion obtained in the step (1) is placed in a sand mill, and the slurry is circulated and sanded 7 times while maintaining the temperature of the dispersion liquid at 95 ° C to obtain a peeled product having a diameter of about 200 nm;

(3) The peeled product prepared in the step (2) is transferred to a high-pressure homogenizer, and the pressure is maintained at 95 ° C under a pressure of 150 MPa, and the high-pressure crushing is performed 3 times.

Example 1-8

In the present embodiment, the micro-nano lignocellulose has a lignin content of 27.5%, a cellulose diameter of 52 nm, and an aspect ratio of 345, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds.

The preparation method specifically comprises the following steps:

(1) Weigh 5g of xylose residue (30% of lignin in xylose residue, 70wt% of cellulose) dissolved in 495mL of 5mol/L urea aqueous solution, heated to 80 ° C and stirred uniformly to obtain xylose residue raw material dispersion;

(2) The xylose residue raw material dispersion obtained in the step (1) is placed in a sand mill, and the slurry is circulated and sanded four times while maintaining the temperature of the dispersion liquid at 80 ° C to obtain a peeled product having a diameter of about 400 nm;

(3) The peeled product prepared in the step (2) is transferred to a high-pressure homogenizer, and under a pressure of 100 MPa, the temperature of the solution is maintained at 80 ° C, and the high-pressure crushing is performed 5 times.

Examples 1-9 to 1-16 are the micro-nano lignocelluloses prepared in Examples 1-1 to 1-8 applied to corrugated packaging paper: the softwood pulp was separately obtained from Examples 1-1 to 1-8. The micro-nano lignocellulose dispersion was mixed, and the mass ratio of the softwood pulp to the micro-nanolignin cellulose was 9.5:0.5, and the paper was super-paper. After completion, the physical examination was carried out for 24 hours, and Table 1-1 shows the utilization. The test results of the corrugated wrapping paper prepared by the micro-nanolignin cellulose of Examples 1-9 to 1-16.

Table 1-1 Comparison of performance of coniferous wood wrapping paper and composite paper

	抗张指数(N·m/g)Tensile index (N·m/g)	耐破指数(Kpa·m2/g)Breaking index (Kpa·m2/g)
针叶木浆Softwood pulp	6060	3.43.4
实施例1-9Example 1-9	9595	4.94.9
实施例1-10Examples 1-10	9696	4.74.7
实施例1-11Example 1-11	9898	4.54.5
实施例1-12Example 1-12	8989	4.34.3
实施例1-13Example 1-13	7575	4.14.1
实施例1-14Example 1-14	7171	3.83.8
实施例1-15Example 1-15	108108	5.35.3
实施例1-16Example 1-16	8888	4.64.6

It can be seen from Table 1-1 that with the addition of 5wt% micro-nanolignin cellulose, the tensile index and the bursting index of the composite wrapping paper are increased by 18.3%-80% and 11.7%-55.8%, respectively, which have better reinforcing effects.

Example 1-17~1-24

Examples 1-17 to 1-24 are the micro-nano lignocellulosic fibers prepared in Examples 1-1 to 1-8 applied to a polypropylene composite material:

The dispersions of the micro-nano lignocellulosic fibers of Examples 1-1 to 1-8 were post-treated to obtain micro-nano lignocellulosic fiber powders, which were respectively extruded and blended with polypropylene at a mass ratio of 3:7. Injection molding prepared strips for mechanical performance testing. Table 1-2 shows the test results of polypropylene and composite materials prepared using the micro-nanolignin cellulose fibers of Examples 1-1 to 1-8.

Table 1-2 Comparison of tensile properties of polypropylene and composites

	拉伸模量(GPa)Tensile modulus (GPa)	拉伸强度(MPa)Tensile strength (MPa)
聚丙烯Polypropylene	1.11.1	2828
实施例1-17Example 1-17	4.14.1	5858
实施例1-18Example 1-18	4.64.6	6868
实施例1-19Example 1-19	4.84.8	7575
实施例1-20Example 1-20	3.53.5	4545
实施例1-21Example 1-21	3.23.2	4949
实施例1-22Example 1-22	3.93.9	5555
实施例1-23Example 1-23	5.85.8	9393
实施例1-24Example 1-24	5.55.5	9191

It can be seen from Table 1-2 that the addition of 30wt% micro-nano lignocellulose increases the tensile film strength and tensile strength of the composite by 190.9%-427% and 60.7%-232%, respectively, and has a better reinforcing effect.

Comparative example 1-1

In this comparative example, the preparation method is as follows:

(1) Weigh 10g of xylose residue dissolved in 490mL of 5mol / L urea aqueous solution, and keep stirring at 25 ° C to obtain a xylose residue raw material dispersion;

(2) The xylose residue raw material dispersion obtained in the step (1) is placed in a sand mill, and the slurry is circulated and sanded once while maintaining the temperature of the dispersion liquid at 25 ° C to obtain a peeled product having a diameter of about 2400 nm;

(3) The peeled product prepared in the step (2) was transferred to a high-pressure homogenizer, and crushed 5 times under high pressure at a pressure of 60 MPa to obtain a micro-nanocellulose having a diameter of D90 = 1800 nm and an aspect ratio of 10.

Comparative example 1-2

Different from Example 1-1, in step (1), the aqueous urea solution is heated to 130 ° C, and 10 g of xylose residue is dissolved in 490 mL of a 5 mol/L urea aqueous solution to obtain a xylose residue raw material dispersion, because the temperature exceeds 100. °C, a large amount of steam is generated during mechanical pretreatment and high pressure homogenization, so the mechanical stripping process cannot be operated normally, and micro-nano lignocellulose cannot be produced.

Comparative example 1-3

The difference from the embodiment 1-1 is that the step (1) is: dissolving 10 g of xylose residue in 490 mL of a 5 mol/L aqueous solution of formamide, heating to 72 ° C and stirring uniformly to obtain a xylose residue raw material dispersion; And step (3) are the same as in the embodiment 1-1. The nanocellulose was obtained to have a diameter of 852 nm and an aspect ratio of 50, and the peeling effect in the urea solution could not be achieved.

Comparative example 1-4

Different from the first embodiment, the lignin in the micro-nano lignocellulose is bonded to the cellulose only in the form of hydrogen bonds, that is, the nano cellulose is physically mixed with the solvent lignin to obtain a lignin content of 22%. Cellulose. The composite material was prepared according to the method of Examples 1-17, and 30% by weight was added. The tensile film strength and tensile strength of the composite material were increased by 82% and 48%, respectively, and the reinforcing effect was greatly reduced.

In order to verify that lignin in the micro-nano lignocellulosic fibers of Examples 1-1 to 1-8 was combined with cellulose in the form of hydrogen bonds and chemical bonds, the following tests were carried out:

The micro-nano lignocellulosic fibers of Examples 1-1 to 1-8 were subjected to carboxymethylation modification so that the degree of product substitution was greater than 1, and the degree of substitution of lignin was less than 0.4 (verified by the lignin model compound). 5 g of the modified product was dispersed in 300 mL of deionized water, stirred thoroughly, and then centrifuged, and the supernatant and the precipitate were freeze-dried to obtain a water-soluble substance and a precipitate, and the mass fraction of the precipitated product of the carboxymethylated product and the micro-nano wood were determined. The content of hemicellulose and lignin in the cellulose fiber was judged according to the content of the precipitate, and the chemical bond between the lignin and the cellulose was judged. The test results are shown in Table 1-3.

Table 1-3

	半纤维素(wt％)Hemicellulose (wt%)	木质素(wt％)Lignin (wt%)	沉淀物(wt％)Precipitate (wt%)
实施例1-1Example 1-1	6.56.5	22twenty two	4848
实施例1-2Example 1-2	77	2525	43.243.2
实施例1-3Examples 1-3	6.86.8	2828	39.139.1

实施例1-4Examples 1-4	7.37.3	22twenty two	35.635.6
实施例1-5Examples 1-5	26.326.3	2727	62.562.5
实施例1-6Example 1-6	25.425.4	2626	67.667.6
实施例1-7Example 1-7	17.517.5	22twenty two	51.651.6
实施例1-8Example 1-8	6.96.9	27.527.5	45.345.3
对比例1-4Comparative example 1-4	00	22twenty two	16.316.3

The carboxymethylation modified degree of polysaccharide compound can be dissolved in water when the degree of substitution is more than 0.4, while the lignin has low degree of carboxymethylation and is insoluble in water. Hemicellulose has a stable chemical bond with lignin, and even if the hemicellulose carboxymethylation degree of substitution is greater than 0.4, it will be partially present in the precipitated portion of the carboxymethylated product. However, as can be seen from Tables 1-3, the mass fraction of the precipitates after carboxymethylation modification of the micro-nano lignocellulose fibers prepared in Examples 1-1 to 1-8 is far greater than that of the pre-modified lignin and the half. The sum of the mass fractions of cellulose indicates that the carboxymethylated cellulose is present in the precipitated portion of the carboxymethylated product, and the lignin has a chemical bond with the cellulose in the prepared micro-nanolignin cellulose fiber. After carboxymethylation modification of the product of Comparative Example 1-4, the lignin content was 16.3 wt%, which was consistent with the mass fraction of the precipitate, indicating that carboxymethyl cellulose was not present in the precipitate, and lignin was not chemically bonded to cellulose. .

It can be seen from the comparison of Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-4 that the preparation method of the present application can realize mechanical pretreatment and high pressure homogenizer in a certain temperature urea aqueous solution. High-lignin content micro-nano lignocellulose can be directly produced by using plant fiber raw materials; if the temperature is lower than this temperature range, efficient high-pressure homogenization of cellulose can not be performed, and it is difficult to obtain nanocellulose; High, it will produce a lot of water vapor, which makes the mechanical stripping process impossible, and can not produce micro-nano lignocellulose. It can be seen from Examples 1-9 to 1-16 and Examples 1-17 to 1-24 that the micro-nano lignocellulose prepared by the present invention is composited with other materials to prepare a composite material, which can significantly improve the properties of the material.

Example 2-1

A micro-nano lignocellulose prepared by the following method:

(1) Weigh 10g of xylose residue (containing 70wt% cellulose, 28wt% lignin and 2wt% hemicellulose) extracted from corn cob in 490mL deionized water and heated to 60 °C Stir well to obtain a raw material dispersion (concentration 2wt%);

(2) The xylose residue raw material dispersion obtained in the step (1) is placed in a sand mill, and the mixture is sanded twice while maintaining the temperature of the raw material dispersion liquid at 60 ° C to obtain a peeled product having a diameter of about 400 nm;

(3) The exfoliate prepared in the step (2) was transferred to a high-pressure homogenizer at a pressure of 75 MPa, and the solution was subjected to high-pressure crushing 5 times at 60 ° C to obtain a dispersion of micro-nano lignocellulose.

The micro-nano lignocellulose has a diameter of between 100 and 150 nm, an aspect ratio ranging from 220 to 250, and a lignin content of 26 wt%.

Example 2-2 to 2-6

A micro-nano lignocellulose differs from Example 2-1 only in that the temperature at which step (1) is stirred is 50 ° C (Example 2-2), 70 ° C (Example 2-3), 75 °C (Examples 2-4), 80 °C (Examples 2-5), and 85 °C (Examples 2-6).

The micro-nanolignin cellulose obtained in Example 2-2 had a diameter of 80 to 170 nm, an aspect ratio of 230 to 260, and a lignin content of 27% by weight.

The micro-nanolignin cellulose obtained in Example 2-3 has a diameter of 100 to 180 nm, an aspect ratio of 280 to 320, and a lignin content of 25% by weight.

The micro-nanolignin cellulose obtained in Example 2-4 had a diameter of between 110 and 190 nm, an aspect ratio ranging from 270 to 310, and a lignin content of 24% by weight.

The micro-nanolignin cellulose obtained in Example 2-5 had a diameter of between 120 and 200 nm, an aspect ratio ranging from 265 to 320, and a lignin content of 24% by weight.

The micro-nanolignin cellulose obtained in Examples 2-6 had a diameter of between 20 and 60 nm, an aspect ratio ranging from 200 to 210, and a lignin content of 22% by weight.

Example 2-7~2-10

A micro-nano lignocellulose differs from Example 2-1 only in that the mixing ratio of xylose slag and water is adjusted, and the concentration of the raw material dispersion in step (1) is obtained as 0.08 wt%, respectively (Example 2 7), 5 wt% (Examples 2-8), 8 wt% (Examples 2-9), 18 wt% (Examples 2-10).

The micro-nanolignin cellulose obtained in Examples 2-7 had a diameter of 80 to 100 nm, an aspect ratio ranging from 210 to 230, and a lignin content of 22% by weight.

The micro-nanolignin cellulose obtained in Examples 2-8 had a diameter of between 110 and 180 nm, an aspect ratio ranging from 250 to 280, and a lignin content of 23% by weight.

The micro-nanolignin cellulose obtained in Examples 2-9 each had a diameter of between 120 and 190 nm, an aspect ratio ranging from 270 to 320, and a lignin content of 24% by weight.

The micro-nanolignin cellulose obtained in Examples 2-10 each had a diameter of 130 to 200 nm, an aspect ratio ranging from 265 to 300, and a lignin content of 25 wt%.

Example 2-11

A micro-nano lignocellulose prepared by the following method:

(2) The xylose residue raw material dispersion obtained in the step (1) is placed in a sand mill, and the slurry is pulverized once while maintaining the temperature of the raw material dispersion liquid at 70 ° C to obtain a peeled product having a diameter of about 800 nm;

(3) The exfoliate prepared in the step (2) was transferred to a high-pressure homogenizer at a pressure of 170 MPa, and the solution was subjected to high-pressure crushing 3 times while maintaining the solution temperature at 80 ° C to obtain a dispersion of micro-nano lignocellulose.

The micro-nanolignin cellulose has a diameter of between 300 and 550 nm, an aspect ratio ranging from 100 to 250, and a lignin content of 25 wt%.

Example 2-12

A micro-nano lignocellulose prepared by the following method:

(2) The xylose residue raw material dispersion obtained in the step (1) is placed in a sand mill, and is circulated and sanded 5 times while maintaining the temperature of the raw material dispersion liquid at 80 ° C to obtain a peeled product having a diameter of about 180 nm;

(3) transferring the stripper prepared in the step (2) to a high-pressure homogenizer, and dispersing the micro-nano lignocellulose at a pressure of 55 MPa while maintaining the temperature of the solution at 70 ° C for 7 times under high pressure. liquid.

The micro-nano lignocellulose has a diameter of between 50 and 100 nm, an aspect ratio ranging from 220 to 270, and a lignin content of 25 wt%.

Example 2-13

The difference from Example 2-3 is that the equivalent mass of the xylose residue is the xylose residue (containing 65 wt% of cellulose, 25 wt% of lignin, 10 wt% of hemicellulose) after hemicellulose extraction from corn stover.

The micro-nano lignocellulose has a diameter of between 142 and 156 nm, an aspect ratio ranging from 210 to 240, and a lignin content of 21% by weight.

Example 2-14

The difference from Example 2-3 is that the equivalent mass of the xylose residue is the xylose residue (containing 65 wt% of cellulose, 30 wt% of lignin, and 5 wt% of hemicellulose) after hemicellulose extraction from wood.

The micro-nano lignocellulose has a diameter of between 152 and 166 nm, an aspect ratio ranging from 210 to 230, and a lignin content of 29 wt%.

Example 2-15

After the step (3) of Example 2-1, the step (4) is carried out to spray-dry the micro-nano lignocellulose dispersion to obtain micro-nanolignin cellulose.

The micro-nano lignocellulose is redispersed in water and arranged as a dispersion. The micro-nanocellulose has a diameter of 80 to 120 nm, an aspect ratio ranging from 210 to 250, and a lignin content of 22% by weight.

Example 2-16~2-18

The difference from Example 2-1 is that 2.5 mol of urea (Preparation Example 2-16), 5.0 mol of urea (Preparation Example 2-17), and 0.5 mol of urea are added to the raw material dispersion of the step (1) (Preparation Example) 2-18).

The micro-nanolignin cellulose obtained in Examples 2-16 had a diameter of between 200 and 250 nm, an aspect ratio ranging from 220 to 250, and a lignin content of 26% by weight.

The micro-nanolignin cellulose obtained in Examples 2-17 had a diameter of 220 to 260 nm, an aspect ratio ranging from 230 to 260, and a lignin content of 26% by weight.

The micro-nanolignin cellulose obtained in Examples 2-18 had a diameter of 160 to 190 nm, an aspect ratio ranging from 180 to 220, and a lignin content of 26% by weight.

Comparative example 2-1

The difference from Example 2-1 was that the temperature at which the step (1) was stirred was 45 °C.

The micro-nanolignin cellulose prepared in Comparative Example 2-1 had a diameter of between 200 and 300 nm, an aspect ratio ranging from 50 to 100, and a lignin content of 26% by weight.

Comparative Example 2-2

Nanocellulose having a diameter of 100 to 150 nm and an aspect ratio of 220 to 250 is physically mixed with lignin in an aqueous solution to obtain cellulose having a lignin content of 26%.

Application Examples 2-1 to 2-18 and Comparative Application Examples 2-1 to 2-2 are micro-nano lignocelluloses prepared by using Examples 2-1 to 2-18 and Comparative Examples 2-1 to 2-2. In corrugated packaging paper: the softwood pulp is mixed with the micro-nano lignocellulose dispersions of Examples 2-1 to 2-18 and Comparative Examples 2-1 to 2-2, respectively, and the softwood pulp and the micro-nanolignin fiber. The mass ratio was 9.5:0.5, and papermaking was carried out. After completion, the physical examination was performed for 24 hours, and Table 2-1 shows the application examples 2-1 to 2-18 and the comparative application examples 2-1 to 2-2. The detection results of corrugated wrapping paper prepared by micro-nano lignocellulose.

Table 2-1 Comparison of performance of coniferous wood wrapping paper and composite paper

项目project	微纳米木质素纤维素Micro-nanolignin cellulose	抗张指数(N·m/g)Tensile index (N·m/g)	耐破指数(kpa·m ²/g) Breaking index (kpa·m ² /g)
针叶木浆Softwood pulp	————	6060	3.43.4
应用例2-1Application Example 2-1	实施例2-1Example 2-1	7373	4.04.0
应用例2-2Application Example 2-2	实施例2-2Example 2-2	7070	3.83.8
应用例2-3Application Example 2-3	实施例2-3Example 2-3	9595	4.64.6
应用例2-4Application Example 2-4	实施例2-4Example 2-4	9696	4.74.7
应用例2-5Application Example 2-5	实施例2-5Example 2-5	9898	4.84.8
应用例2-6Application Example 2-6	实施例2-6Example 2-6	7575	4.24.2
应用例2-7Application Example 2-7	实施例2-7Example 2-7	6868	3.93.9
应用例2-8Application Example 2-8	实施例2-8Example 2-8	9494	4.44.4
应用例2-9Application Example 2-9	实施例2-9Example 2-9	9696	4.74.7
应用例2-10Application Example 2-10	实施例2-10Example 2-10	8888	4.34.3
应用例2-11Application Example 2-11	实施例2-11Example 2-11	8787	4.04.0
应用例2-12Application Example 2-12	实施例2-12Example 2-12	9393	4.24.2
应用例2-13Application Example 2-13	实施例2-13Example 2-13	9292	4.04.0
应用例2-14Application Example 2-14	实施例2-14Example 2-14	9595	4.64.6
应用例2-15Application Example 2-15	实施例2-15Example 2-15	7373	4.24.2
应用例2-16Application Example 2-16	实施例2-16Example 2-16	9898	4.74.7
应用例2-17Application Example 2-17	实施例2-17Example 2-17	9797	4.74.7
应用例2-18Application Example 2-18	实施例2-18Example 2-18	9696	4.54.5
对比例应用例2-1Comparative application example 2-1	对比例2-1Comparative example 2-1	6262	3.43.4
对比例应用例2-2Comparative Example Application Example 2-2	对比例2-2Comparative Example 2-2	6565	3.63.6

It can be seen from Table 2-1 that with the addition of 5wt% micro-nanolignin cellulose, the tensile index and the bursting index of the composite wrapping paper are increased by 13.3%-63% and 11.7%-41%, respectively, which have a better reinforcing effect. Especially when the temperature of the aqueous solution in step (1) of the micro-nano lignocellulose preparation method is 70-80 ° C, the tensile index and the fracture-resistant index of the composite wrapping paper are increased by 58.3%-63% and 40%-41%, respectively. . When the temperature of the raw material dispersion liquid is lower than 50 ° C (Comparative Example 2-1) in the preparation method of the micro-nano lignocellulose provided by the present application, the cellulose raw material containing lignin cannot be sufficiently peeled off, for the composite wrapping paper. The effect of improving the tensile index and the fracture resistance index is not obvious; when the nano-cellulose and lignin are mixed by physical methods, the two cannot be effectively combined, and the improvement effect of the tensile index and the fracture-resistant index of the composite wrapping paper is also not obvious.

Application Examples 2-19 to 2-35 and Comparative Application Examples 2-3 to 2-4 were prepared in Examples 2-1 to 2-14, 2-16 to 2-18, and Comparative Examples 2-1 to 2-2. Micro-nano lignocellulosic fiber for polypropylene composites:

The dispersions of the micro-nano lignocellulosic fibers of Examples 2-1 to 2-14 were spray-dried to obtain micro-nano lignocellulose powders, which were respectively extruded and blended with polypropylene at a mass ratio of 3:7. Injection molding prepared strips for mechanical performance testing. Table 2-2 shows the test results of polypropylene and composite materials prepared using the micro-nanolignin cellulose fibers of Examples 2-1 to 2-14 and Comparative Examples 2-1 to 2-2.

Table 2-2 Comparison of tensile properties of polypropylene and composites

项目project	微纳米木质素纤维素Micro-nanolignin cellulose	拉伸模量(GPa)Tensile modulus (GPa)	拉伸强度(MPa)Tensile strength (MPa)
聚丙烯Polypropylene	————	1.11.1	2828
应用例2-19Application Example 2-19	实施例2-1Example 2-1	4.14.1	5858
应用例2-20Application Example 2-20	实施例2-2Example 2-2	3.83.8	5454
应用例2-21Application Example 2-21	实施例2-3Example 2-3	4.64.6	7070
应用例2-22Application Example 2-22	实施例2-4Example 2-4	4.74.7	7171
应用例2-23Application Example 2-23	实施例2-5Example 2-5	4.84.8	7272
应用例2-24Application Example 2-24	实施例2-6Example 2-6	4.24.2	7373
应用例2-25Application Example 2-25	实施例2-7Example 2-7	4.04.0	6363
应用例2-26Application Example 2-26	实施例2-8Example 2-8	4.54.5	6767
应用例2-27Application Example 2-27	实施例2-9Example 2-9	4.64.6	7070
应用例2-28Application Example 2-28	实施例2-10Example 2-10	4.24.2	6969
应用例2-29Application Example 2-29	实施例2-11Example 2-11	4.14.1	6969
应用例2-30Application Example 2-30	实施例2-12Example 2-12	4.44.4	7373
应用例2-31Application Example 2-31	实施例2-13Example 2-13	4.34.3	7474
应用例2-32Application Example 2-32	实施例2-14Example 2-14	4.44.4	7373
应用例2-33Application Example 2-33	实施例2-16Example 2-16	4.94.9	7575
应用例2-34Application Example 2-34	实施例2-17Example 2-17	4.84.8	7575
应用例2-35Application Example 2-35	实施例2-18Example 2-18	4.74.7	7676
对比例应用例2-3Comparative Example Application Example 2-3	对比例2-1Comparative example 2-1	1.51.5	3232
对比例应用例2-4Comparative application example 2-4	对比例2-2Comparative Example 2-2	2.32.3	4040

It can be seen from Table 2-2 that the addition of 30wt% micro-nano lignocellulose increases the tensile film strength and tensile strength of the composite by 245%-336% and 92.8%-164%, respectively, and has a better reinforcing effect. When the temperature of the raw material dispersion liquid is lower than 50 ° C (Comparative Example 2-1) in the preparation method of the micro-nano lignocellulose provided by the present application, the cellulose raw material containing lignin cannot be sufficiently peeled off, and the composite material is pulled. The effect of improving the film stretch and tensile strength is not obvious; when the nanocellulose and lignin are mixed by physical methods, the two can not be effectively combined, and the effect of the tensile film amount and tensile strength of the composite material is also not obvious.

In order to verify that lignin in the micro-nano lignocellulosic fibers of Examples 2-1 to 2-14, 2-16 to 2-18 was combined with cellulose in the form of hydrogen bonds and chemical bonds, the following test was conducted: Example 2 The micro-nano lignocellulosic fibers of -1 to 2-14, 2-16 to 2-18 and Comparative Example 2-2 were modified by carboxymethylation to give a product substitution degree of more than 1, and a lignin substitution degree of less than 0.4. (Verified by lignin model compounds). 5 g of the modified product was dispersed in 300 mL of deionized water, stirred thoroughly, and then centrifuged, and the supernatant and the precipitate were freeze-dried to obtain a water-soluble substance and a precipitate, and the mass fraction of the precipitated product of the carboxymethylated product and the micro-nano wood were determined. The content of hemicellulose and lignin in the cellulose fiber was judged according to the content of the precipitate, and the chemical bond between lignin and cellulose was judged. The test results are shown in Table 2-3.

Table 2-3

样品sample	半纤维素Hemicellulose	木质素Lignin	沉淀物Precipitate	样品sample	半纤维素Hemicellulose	木质素Lignin	沉淀物Precipitate
实施例2-1Example 2-1	2wt％2wt%	28wt％28wt%	40.2wt％40.2wt%	实施例2-10Example 2-10	2wt％2wt%	28wt％28wt%	40.2wt％40.2wt%
实施例2-2Example 2-2	2wt％2wt%	28wt％28wt%	40.3wt％40.3wt%	实施例2-11Example 2-11	2wt％2wt%	28wt％28wt%	40.3wt％40.3wt%
实施例2-3Example 2-3	2wt％2wt%	28wt％28wt%	40.5wt％40.5wt%	实施例2-12Example 2-12	2wt％2wt%	28wt％28wt%	40.2wt％40.2wt%
实施例2-4Example 2-4	2wt％2wt%	28wt％28wt%	40.7wt％40.7wt%	实施例2-13Example 2-13	10wt％10wt%	25wt％25wt%	45.2wt％45.2wt%
实施例2-5Example 2-5	2wt％2wt%	28wt％28wt%	40.4wt％40.4wt%	实施例2-14Example 2-14	5wt％5wt%	30wt％30wt%	45.6wt％45.6wt%
实施例2-6Example 2-6	2wt％2wt%	28wt％28wt%	40.1wt％40.1wt%	实施例2-16Example 2-16	2wt％2wt%	28wt％28wt%	40.3wt％40.3wt%
实施例2-7Example 2-7	2wt％2wt%	28wt％28wt%	40.2wt％40.2wt%	实施例2-17Example 2-17	2wt％2wt%	28wt％28wt%	40.5wt％40.5wt%
实施例2-8Example 2-8	2wt％2wt%	28wt％28wt%	40.3wt％40.3wt%	实施例2-18Example 2-18	2wt％2wt%	28wt％28wt%	40.8wt％40.8wt%
实施例2-9Example 2-9	2wt％2wt%	28wt％28wt%	40.5wt％40.5wt%	对比例2-2Comparative Example 2-2	0wt％0wt%	22wt％22wt%	16.3wt％16.3wt%

The carboxymethylation modified degree of polysaccharide compound can be dissolved in water when the degree of substitution is more than 0.4, while the lignin has low degree of carboxymethylation and is insoluble in water. Hemicellulose has a stable chemical bond with lignin, and even if the hemicellulose carboxymethylation degree of substitution is greater than 0.4, it will be partially present in the precipitated portion of the carboxymethylated product. However, as can be seen from Table 2-3, the mass fraction of the precipitates after carboxymethylation modification of the micro-nano lignocellulose fibers prepared in Examples 2-1 to 2-14 is much larger than that of the pre-modified lignin and the half. The sum of the mass fractions of cellulose indicates that the carboxymethylated cellulose is present in the precipitated portion of the carboxymethylated product, and the lignin has a chemical bond with the cellulose in the prepared micro-nanolignin cellulose fiber. After carboxymethylation modification of the product of Comparative Example 2-2, the lignin content was 16.3 wt%, which was consistent with the mass fraction of the precipitate, indicating that carboxymethyl cellulose was not present in the precipitate, and lignin was not chemically bonded to cellulose. .

From the comparison of Examples 2-1 to 2-18, Application Examples 2-1 to 2-35, and Comparative Examples 2-1 to 2-2 and the comparative examples, it can be seen that the preparation method described in the present application can be realized at 50. Dispersing cellulose raw materials containing lignin in an aqueous solution above °C in combination with mechanical pretreatment and high-pressure homogenizer homogenization can directly produce high-lignin content micro-nano lignocellulose using plant fiber raw materials; the temperature is lower than this temperature range It is difficult to obtain effective high-pressure homogenization of cellulose, and it is difficult to obtain nano-cellulose; if the temperature is too high, the chemical structure of lignin itself will be broken, and lignin will be freed from cellulose, and micro-nano-lignin fiber will be reduced. The content of lignin in the prime. The micro-nano lignocellulose prepared by the present invention is combined with other materials to prepare a composite material, which can significantly improve the performance of the material.

Example 3-1

In this embodiment, the micro-nano lignocellulose dispersion is prepared by the following method, specifically comprising the following steps:

(1) Weigh 97g of N,N-dimethylformamide to 90 ° C, weigh 3g of dried xylose residue (where the lignin content in the sugar residue is 25wt%, the cellulose content is 70wt%, semi-fiber a content of 5 wt%) is added to the heated N, N-dimethylformamide to obtain a xylose residue raw material dispersion;

(2) The xylose residue raw material dispersion obtained in the step (1) is circulated and sanded once while maintaining the temperature of the dispersion liquid at 90 ° C to obtain a peeled product having a diameter of about 500 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the solution is subjected to high-pressure crushing for 7 cycles under a pressure of 60 MPa while maintaining the solution temperature at 90 ° C to obtain a diameter of 20-130 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 2.85%, and a lignin content of 25% of the micro-nanolignin cellulose solid content.

2 is a TEM image obtained by using a JEM-1200EX (120KV) type transmission electron microscope test for the micro-nano lignocellulose dispersion prepared in the present embodiment. It can be seen from the figure that most of the cellulose is defibrated to less than 100 nm, and the aspect ratio is high, and the layers are connected to each other in a network structure.

Example 3-2

(1) Weigh 97g of N,N-dimethylformamide to 72°C; weigh 3g of dried xylose residue (where the lignin content in the xylose residue is 28wt%, the cellulose content is 70wt%, hemicellulose a content of 2% by weight) is added to the heated N, N-dimethylformamide to obtain a xylose residue raw material dispersion;

(2) The xylose residue raw material dispersion obtained in the step (1) is circulated and sanded once while maintaining the temperature of the dispersion liquid at 72 ° C to obtain a peeled product having a diameter of about 500 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out for 5 cycles under the pressure of 100 MPa while maintaining the solution temperature at 72 ° C to obtain a diameter of 10-100 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 2.79%, and a lignin content of 28% of the micro-nanolignin cellulose solid content.

3 is a TEM image obtained by using a JEM-1200EX (120KV) type transmission electron microscope to obtain a micro-nano lignocellulose dispersion prepared in the present embodiment. It can be seen from the figure that all cellulose is defibrated to less than 100 nm. The size is relatively more uniform and the aspect ratio is high.

Example 3-3

(1) Weigh 95g of ethanol to 72 ° C; weigh 5g of dried xylose residue (where the lignin content of xylose residue is 28wt%, the cellulose content is 70wt%, and the hemicellulose content is 2wt%) In the heated ethanol, a xylose residue raw material dispersion is obtained;

(2) The xylose residue raw material dispersion obtained in the step (1) is circulated and sanded three times while maintaining the temperature of the dispersion liquid at 72 ° C to obtain a peeled product having a diameter of about 300 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out for 3 cycles under the pressure of 80 MPa while maintaining the solution temperature at 72 ° C to obtain a diameter of 30-100 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 4.79%, and a lignin content of 27% of the micro-nanolignin cellulose solid content.

Example 3-4

(1) Weighing 90 g of n-butanol to 100 ° C; weighing 10 g of dried xylose residue (in which the lignin content of the xylose residue is 25 wt%, the cellulose content is 75 wt%) is added to the heated n-butanol In the middle, a xylose residue raw material dispersion is obtained;

(2) The xylose residue raw material dispersion obtained in the step (1) is subjected to sanding 5 times while maintaining the temperature of the dispersion liquid at 100 ° C to obtain a peeled product having a diameter of about 150 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out for 3 cycles under the pressure of 50 MPa while maintaining the solution temperature at 100 ° C to obtain a diameter of 5-80 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 9.55%, and a lignin content of 26% of the micro-nanolignin cellulose solid content.

Example 3-5

(1) Weigh 92g of xylene to 100 ° C; weigh 8g of dried xylose residue (where the lignin content of the xylose residue is 25wt%, the cellulose content is 70wt%, the hemicellulose content is 5wt%) Into the heated xylene, a xylose residue raw material dispersion is obtained;

(2) The xylose residue raw material dispersion obtained in the step (1) is subjected to secondary sanding while maintaining the temperature of the dispersion liquid at 100 ° C to obtain a peeled product having a diameter of about 400 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out for 7 cycles under the pressure of 150 MPa while maintaining the solution temperature at 100 ° C to obtain a diameter of 5-15 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 7.12%, and a lignin content of 27% of the micro-nanolignin cellulose solid content.

Example 3-6

(1) Weigh 80 g of dimethyl sulfoxide to 128 ° C; weigh 20 g of dried xylose residue (in which the lignin content of xylose residue is 22 wt%, the cellulose content is 78 wt%) is added to the heated two In methyl sulfoxide, a xylose residue raw material dispersion is obtained;

(2) The xylose residue raw material dispersion obtained in the step (1) is subjected to secondary sanding while maintaining the temperature of the dispersion liquid at 128 ° C to obtain a peeled product having a diameter of about 500 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out for 3 cycles under the pressure of 80 MPa while maintaining the solution temperature at 128 ° C to obtain a diameter of 100-250 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 17.62%, and a lignin content of 23% of the micro-nanolignin cellulose solid content.

Example 3-7

(1) Weigh 99g of pyridine to 105 ° C; weigh 1g of dried xylose residue (where the lignin content of the xylose residue is 25wt%, the cellulose content is 65wt%, the hemicellulose content is 10wt%) In the heated pyridine, a xylose residue raw material dispersion is obtained;

(2) The xylose residue raw material dispersion obtained in the step (1) is subjected to cyclic sanding 7 times while maintaining the temperature of the dispersion liquid at 105 ° C to obtain a peeled product having a diameter of about 200 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out for 5 cycles under the pressure of 100 MPa while maintaining the solution temperature at 105 ° C to obtain a diameter of 10-20 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 0.75%, and a lignin content of 22.5% of the micro-nanolignin cellulose solid content.

Example 3-8

(1) Weigh 95g of carbon tetrachloride to 72°C; weigh 5g of dried xylose residue (where the lignin content in the xylose residue is 28wt%, the cellulose content is 70wt%, and the hemicellulose content is 2wt%) Adding to the heated carbon tetrachloride to obtain a xylose residue raw material dispersion;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out for 3 cycles under the pressure of 150 MPa while maintaining the solution temperature at 72 ° C to obtain a diameter of 150-250 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 4.58%, and a lignin content of 24.5% solid content of the micro-nanolignin cellulose.

Example 3-9

(1) Weigh 90g of N,N-dimethylacetamide to 120 ° C; weigh 10g of dried xylose residue (where the lignin content of xylose residue is 20wt%, cellulose content is 80wt%) In the heated N,N-dimethylacetamide, a xylose residue raw material dispersion is obtained;

(2) The xylose residue raw material dispersion obtained in the step (1) is circulated and sanded twice while maintaining the temperature of the dispersion liquid at 120 ° C to obtain a peeled product having a diameter of about 300 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out for 7 cycles under the pressure of 80 MPa while maintaining the solution temperature at 120 ° C to obtain a diameter of 5-100 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 8.11%, and a lignin content of 21% of the micro-nanolignin cellulose solid content.

Example 3-10

(1) Weigh 95g of octane to 120 ° C; weigh 5g of dried xylose slag xylose residue (where the lignin content in the sugar residue is 25wt%, the cellulose content is 68wt%, and the hemicellulose content is 7wt %) is added to the heated octane to obtain a xylose residue raw material dispersion;

(2) The xylose residue raw material dispersion obtained in the step (1) is circulated and sanded three times while maintaining the temperature of the dispersion liquid at 120 ° C to obtain a peeled product having a diameter of about 300 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and the high-pressure crushing is carried out for 3 cycles under the pressure of 60 MPa while maintaining the solution temperature at 120 ° C to obtain a diameter of 100-200 nm and a length. A micro-nano lignocellulose dispersion having a content of more than 2 μm, a micro-nanocellulose content of 4.41%, and a lignin content of 22% of the micro-nanolignin cellulose solid content.

Example 3-11

The difference between the present embodiment and the embodiment 3-1 is that the step (2) is: the xylose residue raw material dispersion obtained in the step (1) is subjected to wire grinding while maintaining the temperature of the dispersion liquid at 90 ° C, and the cycle 15 The same procedure as in Example 3-1 was carried out except that a peeled product having a diameter of about 500 nm was obtained.

The micro-nanocellulose in the obtained micro-nano lignocellulose dispersion has a diameter of 20-150 nm, a length of more than 2 μm, a micro-nanocellulose content of 2.55%, and a lignin content of 24% of the micro-nanolignin cellulose solid content.

Example 3-12

The difference between the present embodiment and the embodiment 3-1 is that the step (2) is: the xylose residue raw material dispersion obtained in the step (1) is ball-milled while the dispersion temperature is maintained at 90 ° C, and the cycle is repeated 10 times. The same procedure as in Example 3-1 was carried out except that a peeled product having a diameter of about 800 nm was obtained.

The prepared micro-nano lignocellulose dispersion has a diameter of 50-200 nm, a length of more than 2 μm, a micro-nanocellulose content of 2.40%, and a lignin content of 23.5 of the micro-nano lignin cellulose solid content. %.

Comparative example 3-1

In this comparative example, the preparation method is as follows:

(1) Weighing 97g of N,N-dimethylformamide to 25 ° C, weighed 3g of dried xylose slag was added to N, N-dimethylformamide to obtain a xylose residue raw material dispersion;

(2) The xylose residue raw material dispersion obtained in the step (1) is placed in a ball mill at a rotation speed of 300 to 500 rpm, and ball-milled at 25 ° C for 5 hours to obtain a peeling material having a diameter of about 2,500 nm;

(3) The stripper prepared in the step (2) is directly transferred to a high-pressure homogenizer, and subjected to high-pressure crushing for 7 cycles under a pressure of 60 MPa while maintaining 25 ° C, and the obtained cellulose dispersion liquid has a diameter of 1500 nm. The size is large, and the dispersion system quickly precipitates and stratifies.

Comparative example 3-2

Different from Example 3-1, the organic solvent was heated to 150 ° C in the step (1), and both the step (2) and the step (3) were also carried out while maintaining the solution temperature at 150 °C. The obtained cellulose dispersion has a cellulose diameter of 10-100 nm, and the lignin content in the micro-nano lignocellulose dispersion is only 5% due to excessive decomposition of the lignin, and the micro-nano lignocellulose dispersion liquid The system is also not stable enough to precipitate.

It can be seen from the comparison of Examples 3-1 to 3-12 and Comparative Examples 3-1 to 3-2 that the preparation method described in the present application can realize mechanical pretreatment and high pressure in an organic system within a certain temperature range. The homogenizer homogenizes to obtain a high lignin content micro-nano lignocellulose dispersion, and the temperature is lower than the temperature range, and the high-pressure homogenization peeling of the cellulose in the organic solvent dispersion system cannot be obtained, and it is difficult to obtain An organic dispersion of suitable size and high lignin content; if the temperature is higher than this temperature range, the smaller size of the micro-nano lignocellulose can not be further obtained, but the lignin content is lowered, so that the dispersion system is not stable enough and is easy to precipitate.

Example 4-1

A method for preparing a micro-nanocellulose composite comprises the following steps:

(1) 10 g of xylose residue (containing 70 wt% of cellulose, 28 wt% of lignin and 2 wt% of hemicellulose) and 0.5 g of graphene (the average thickness of the sheet is 5 nm) from the corn cob Disperse in 200 mL of water and mix well to obtain a dispersion;

(2) placing the dispersion in a ball mill for pre-peeling to obtain a pre-stripped product dispersion (with a peeling product diameter of 200 to 1500 nm);

(3) Dispersing the pre-stripped product dispersion in a high-pressure homogenizer at a cycle of 130 MPa for 3 cycles to obtain a nanocellulose composite dispersion having a diameter of 5 to 20 nm and a lignin content of 28%; the micro/nano fiber The concentration of the dispersion is 4.8 wt%, the diameter of the micro-nanocellulose is in the range of 3 to 7 nm, and the aspect ratio is in the range of 230 to 260.

Example 4-2

The difference from Example 4-1 is that the equivalent mass of the xylose residue is the xylose residue (containing 65 wt% cellulose, 25 wt% lignin, 10 wt% hemicellulose) after extracting hemicellulose from corn stover. .

The concentration of the micro-nanocellulose dispersion obtained in Example 4-2 was 4.8 wt%, the diameter of the micro-nanocellulose was in the range of 20 to 40 nm, and the aspect ratio was in the range of 340 to 380.

Example 4-3

The difference from Example 4-1 is that the equivalent mass of the xylose residue is the xylose residue (containing 65 wt% of cellulose, 30 wt% of lignin, and 5 wt% of hemicellulose) after hemicellulose extraction from wood.

The concentration of the micro-nanocellulose dispersion obtained in Example 4-3 was 4.5% by weight, and the diameter of the micro-nanocellulose was in the range of 10 to 20 nm, and the aspect ratio was in the range of 240 to 250.

Examples 4-4 to 4-6

The difference from Example 4-1 is that graphene having an average thickness of 20 nm (Example 4-4), 3 nm of graphene (Example 4-5), and 10 nm of graphene (Examples 4-6) .

The concentration of the micro-nanocellulose dispersion obtained in Example 4-4 was 4.6 wt%, the diameter of the micro-nanocellulose was in the range of 170 to 210 nm, and the aspect ratio was in the range of 100 to 214.

The concentration of the micro-nanocellulose dispersion obtained in Example 4-5 was 4.75 wt%, the diameter of the micro-nanocellulose was between 10 and 20 nm, and the aspect ratio was in the range of 230 to 270.

The concentration of the micro-nanocellulose dispersion obtained in Examples 4-6 was 4.68 wt%, the diameter of the micro-nanocellulose was between 45 and 55 nm, and the aspect ratio was in the range of 150 to 210.

Example 4-7~4-11

The difference from Example 4-1 is that the addition of the graphene material is 0.1 g of graphene (Example 4-7), 0.6 g of graphene oxide (Example 4-8), and 0.7 g of graphene (Example 4) -9), 0.8 g of graphene (Examples 4-10), and 0.9 g of graphene oxide (Examples 4-11).

The concentration of the micro-nanocellulose dispersion obtained in Examples 4-7 was 4.5% by weight, and the diameter of the micro-nanocellulose was between 3 and 5 nm, and the aspect ratio was 260 to 270.

The concentration of the micro-nanocellulose dispersion obtained in Examples 4-8 was 4.0% by weight, and the diameter of the micro-nanocellulose was between 15 and 25 nm, and the aspect ratio was 235 to 255.

The concentration of the micro-nanocellulose dispersion obtained in Examples 4-9 was 3.8 wt%, and the diameter of the micro-nanocellulose was between 45 and 55 nm, and the aspect ratio was 230 to 250.

The concentration of the micro-nanocellulose dispersion obtained in Examples 4-10 was 3.75 wt%, and the diameter of the micro-nanocellulose was between 90 and 98 nm, and the aspect ratio was 200-220.

The concentration of the micro-nanocellulose dispersion obtained in Examples 4 to 11 was 3.5 wt%, and the diameter of the micro-nanocellulose was between 160 and 170 nm, and the aspect ratio was 170 to 190.

Example 4-12

The difference from Example 4-1 is that the conditions of high pressure homogenization are: 150 MPa cyclic stripping for 5 cycles (Examples 4-12); 50 MPa cycle stripping for 10 cycles (Examples 4-13); 60 MPa cycle stripping 3 Cycling (Examples 4-14); 8 cycles of 80 MPa cyclic stripping (Examples 4-15).

The concentration of the micro-nanocellulose dispersion obtained in Examples 4-12 was 4.78 wt%, and the diameter of the micro-nanocellulose was between 3 and 5 nm, and the aspect ratio was 240 to 260.

The concentration of the micro-nanocellulose dispersion obtained in Examples 4-13 was 4.6 wt%, and the diameter of the micro-nanocellulose was 13 to 19 nm, and the aspect ratio was 230 to 240.

The concentration of the micro-nanocellulose dispersion obtained in Examples 4-14 was 4.55 wt%, and the diameter of the micro-nanocellulose was 45 to 55 nm, and the aspect ratio was 220 to 230.

The concentration of the micro-nanocellulose dispersion obtained in Examples 4-15 was 4.58 wt%, and the diameter of the micro-nanocellulose was 28 to 42 nm, and the aspect ratio was 210 to 225.

Example 4-16

After the step (3) of Example 4-1, the step (4) is carried out to spray-dry the micro-nanocellulose dispersion to obtain a micro-nanocellulose powder.

The micro-nanocellulose has a diameter ranging from 13 to 17 nm and an aspect ratio ranging from 240 to 250.

Comparative Example 4-1

(1) dispersing xylose residue containing 70% by weight of cellulose, 28% by weight of lignin and 2% by weight of hemicellulose from corn cob in 200 mL of water, and uniformly mixing to obtain a dispersion;

(2) placing the dispersion in a ball mill for pre-peeling to obtain a pre-stripped product dispersion;

(3) The pre-stripped product dispersion is placed in a high-pressure homogenizer at 130 MPa for 3 cycles to obtain a micro-nanocellulose composite dispersion having a lignin content of 28%; the concentration of the micro-nanocellulose dispersion The polyamide has a diameter of 1700 to 1900 nm and an aspect ratio of 8 to 12 at 3.3 wt%.

Comparative Example 4-2

(1) 10 g of xylose residue (containing 70% by weight of cellulose, 28% by weight of lignin and 2% by weight of hemicellulose) and 0.5 g of graphite (average thickness of sheet layer of 50 nm) after hemicellulose extraction from corn cob Disperse in 200 mL of water, mix well to obtain a dispersion;

(3) The pre-stripped product dispersion is placed in a high-pressure homogenizer at 130 MPa for 3 cycles to obtain a micro-nanocellulose composite dispersion having a lignin content of 28%; the concentration of the micro-nanocellulose dispersion The micro-nanocellulose has a diameter ranging from 830 to 890 nm and an aspect ratio ranging from 25 to 35.

Comparative Example 4-3

A method for preparing micro-nanocellulose, comprising the following steps:

(1) Dispersing 10 g of bleached wood pulp (containing 85 wt% of cellulose and 15 wt% of hemicellulose) in 200 mL of water, and uniformly mixing to obtain a dispersion;

(3) The pre-stripped product dispersion is placed in a high-pressure homogenizer at 130 MPa for 3 cycles to obtain a nanocellulose dispersion; the concentration of the nanocellulose dispersion is 4.5 wt%, and the diameter range of the nanocellulose It is 30 to 90 nm, and the aspect ratio ranges from 205 to 230.

From the results of the examples and the comparative examples, it can be seen that in the aqueous solution system, the intercalation of the graphene material is performed by means of mechanical pretreatment and high-pressure homogenization without any chemical treatment of the xylose residue. Function, the cellulose is stripped, and a micro-nanocellulose composite having a certain aspect ratio (100-500) is prepared, the diameter of which is 4 to 200 nm, the preparation process is simple and easy to control, and no chemical reagent is used in the preparation process. , environmental protection and no pollution.

Performance test: compatibility test, which was carried out by spray drying the dispersions obtained in Examples 4-1 to 4-15 and Comparative Examples 4-1 to 4-3, and dispersed in the ratio of 0.1% by weight of the powder. In the methyl chloride, the stratification time of the dispersion was observed by standing. The test results are shown in Table 4-1:

Table 4-1

样品sample	溶液分层时间Solution stratification time	样品sample	溶液分层时间Solution stratification time
实施例4-1Example 4-1	＞3个月>3 months	实施例4-10Example 4-10	54天54 days
实施例4-2Example 4-2	＞3个月>3 months	实施例4-11Example 4-11	35天35 days
实施例4-3Example 4-3	＞3个月>3 months	实施例4-12Example 4-12	＞3个月>3 months
实施例4-4Example 4-4	28天28 days	实施例4-13Example 4-13	＞3个月>3 months
实施例4-5Example 4-5	＞3个月>3 months	实施例4-14Example 4-14	＞3个月>3 months
实施例4-6Example 4-6	＞3个月>3 months	实施例4-15Example 4-15	＞3个月>3 months
实施例4-7Example 4-7	＞3个月>3 months	对比例4-1Comparative Example 4-1	瞬间沉淀Instant precipitation
实施例4-8Example 4-8	＞3个月>3 months	对比例4-2Comparative Example 4-2	2小时2 hours

Example 4-9

>3 months

Comparative Example 4-3

3 days

It can be seen from the test results in Table 4-1 that the micro-nanocellulose composite prepared by using xylose residue as a raw material has good dispersibility in an organic solvent, good compatibility with an organic solvent, and can be long. The time is stable so that it is well compatible with oily polymers or oily polymerizable monomers. When the graphene material has a thickness of 3 to 10 nm and the graphene material is added in an amount of 10 wt% or less of the xylose residue, the prepared micro-nanocellulose composite can be stably present in an organic solvent for more than 3 months.

Example 5-1

A micro-nanocellulose composite prepared by the following method:

(1) To 100 kg of an aqueous urea solution having a temperature of 80 ° C and a concentration of 6 wt%, 100 g of expanded graphite and 100 g of xylose residue obtained by extracting hemicellulose from corn cobs (containing 70 wt% of cellulose, 28 wt% of lignin and 2wt% hemicellulose) to obtain a mixed raw material dispersion;

(2) The mixed raw material dispersion was ultrasonically peeled off at a power of 500 kW to obtain a micro-nanocellulose composite dispersion.

The concentration of the micro-nanocellulose composite dispersion is 15% by weight, the diameter of the micro-nanocellulose is in the range of 13 to 17 nm, and the aspect ratio ranges from 230 to 260.

Example 5-2

A micro-nanocellulose composite prepared by the following method:

(1) Adding 0.2 g of flake graphite and 0.8 g of xylose residue after extracting hemicellulose from corn cob to 1 kg of a urea aqueous solution having a temperature of 80 ° C and a concentration of 0.01 wt% (containing 70 wt% of cellulose, 28 wt% Lignin and 2% by weight of hemicellulose) to obtain a mixed raw material dispersion;

(2) The mixed raw material dispersion was ultrasonically peeled off at a power of 1000 kW to obtain a micro-nanocellulose composite dispersion.

The concentration of the micro-nanocellulose composite dispersion is 0.1 wt%, the diameter of the micro-nanocellulose is in the range of 20 to 50 nm, and the aspect ratio ranges from 260 to 280.

Example 5-3

A micro-nanocellulose composite prepared by the following method:

(1) Adding 10 g of expanded graphite and 90 g of xylose residue (containing 70 wt% of cellulose, 28 wt% of lignin, and 1 g of hemicellulose extracted from corn cob to 1 kg of a urea aqueous solution having a temperature of 80 ° C and a concentration of 1 wt%; 2wt% hemicellulose) to obtain a mixed raw material dispersion;

(2) The mixed raw material dispersion was ultrasonically peeled off at a power of 800 kW to obtain a micro-nanocellulose composite dispersion.

The concentration of the micro-nanocellulose composite dispersion is 8.3 wt%, the diameter of the micro-nanocellulose is in the range of 70-100 nm, and the aspect ratio ranges from 230 to 240.

Example 5-4

A micro-nanocellulose composite prepared by the following method:

(1) Adding 70 g of expanded graphite and 10 g of xylose residue after extracting hemicellulose from corn cob to 1 kg of a urea aqueous solution having a temperature of 80 ° C and a concentration of 0.01 wt% (containing 70 wt% of cellulose, 28 wt% of lignin) And 2% by weight of hemicellulose) to obtain a mixed raw material dispersion;

(2) The mixed raw material dispersion was ball-peeled to obtain a micro-nanocellulose composite dispersion.

The concentration of the micro-nanocellulose composite dispersion is 7.2% by weight, the diameter of the micro-nanocellulose is in the range of 150-175 nm, and the aspect ratio ranges from 200 to 206.

Example 5-5

The difference from Example 5-3 is that the equivalent mass of the xylose residue is the xylose residue (containing 65 wt% of cellulose, 25 wt% of lignin, 10 wt% of hemicellulose) after hemicellulose extraction from corn stover.

The concentration of the micro-nanocellulose composite dispersion is 8.3 wt%, the diameter of the micro-nanocellulose is in the range of 140-155 nm, and the aspect ratio ranges from 206 to 216.

Example 5-6

The difference from Example 5-3 is that the equivalent mass of the xylose residue is the xylose residue (containing 65 wt% of cellulose, 30 wt% of lignin, and 5 wt% of hemicellulose) after hemicellulose extraction from wood.

The concentration of the micro-nanocellulose composite dispersion is 8.2% by weight, the diameter of the micro-nanocellulose is in the range of 155-180 nm, and the aspect ratio ranges from 200 to 220.

Example 5-7

The difference from Example 5-3 was that the concentration of the aqueous urea solution was 5% by weight.

The concentration of the micro-nanocellulose composite dispersion is 8.1% by weight, the diameter of the micro-nanocellulose is in the range of 30-70 nm, and the aspect ratio ranges from 240 to 260.

Example 5-8~5-11

The difference from Example 5-3 is that the temperature of the aqueous urea solution is 72 ° C (Examples 5-8), 90 ° C (Examples 5-9), 100 ° C (Examples 5-10), 65 ° C (Examples) 5-11).

The concentration of the micro-nanocellulose composite dispersion prepared in Examples 5-8 was 8.1% by weight, the diameter of the micro-nanocellulose was in the range of 100 to 130 nm, and the aspect ratio was in the range of 220 to 280.

The concentration of the micro-nanocellulose composite dispersion prepared in Examples 5-9 was 8.2% by weight, the diameter of the micro-nanocellulose was in the range of 10 to 30 nm, and the aspect ratio was in the range of 280 to 311.

The concentration of the micro-nanocellulose composite dispersion prepared in Examples 5-10 was 7.9 wt%, the diameter of the micro-nanocellulose was in the range of 5 to 20 nm, and the aspect ratio was in the range of 270 to 318.

The concentration of the micro-nanocellulose composite dispersion prepared in Examples 5-11 was 8.1% by weight, and the diameter of the micro-nanocellulose was in the range of 250 to 300 nm, and the aspect ratio was in the range of 130 to 160.

Example 5-12

After the step (2) of Example 5-3, the step (3) is carried out to spray-dry the micro-nanocellulose composite dispersion to obtain a micro-nanocellulose powder.

The micro-nanocellulose composite was redispersed in water and arranged to a concentration of 8.1% by weight of the dispersion. The diameter of the micro-nanocellulose was in the range of 80-106 nm, and the aspect ratio ranged from 220 to 240.

Comparative example 5-1

The difference from Example 5-3 is that the mass of the aqueous urea solution or the like is replaced with a pure aqueous solution.

The prepared micro-nanocellulose composite dispersion has a concentration of 8.1% by weight, the micro-nanocellulose has a diameter in the range of 1500 to 1700 nm, and the aspect ratio ranges from 30 to 60.

Comparative Example 5-2

The difference from Example 5-3 was that the mass of the aqueous urea solution or the like was replaced with an aqueous solution of dimethylformamide (DMF) having a concentration of 1% by weight.

The prepared micro-nanocellulose composite dispersion has a concentration of 8.1% by weight, the micro-nanocellulose has a diameter in the range of 500 to 700 nm, and the aspect ratio ranges from 150 to 160.

Comparative Example 5-3

The difference from Example 5-3 is that the mass of xylose residue (containing 70% by weight of cellulose, 28% by weight of lignin and 2% by weight of hemicellulose) after heparin extraction from corn cob is replaced with bleached wood paddle. (containing 85 wt% cellulose and 15 wt% hemicellulose).

The prepared micro-nanocellulose composite dispersion has a concentration of 8.1% by weight, the micro-nanocellulose has a diameter of 70 to 90 nm, and the aspect ratio ranges from 170 to 180.

Performance Testing:

The compatibility test was carried out by spray-drying the dispersions obtained in Examples 5 to 5-12 and Comparative Examples 5-1 to 5-3, and dispersed in dichloromethane at a powder concentration of 0.1% by weight. , stand still to observe the stratification time of the dispersion. The test results are shown in Table 5-1:

Table 5-1

样品sample	溶液分层时间Solution stratification time	样品sample	溶液分层时间Solution stratification time
实施例5-1Example 5-1	40天40 days	实施例5-9Example 5-9	30天30 days
实施例5-2Example 5-2	60天60 days	实施例5-10Example 5-10	45天45 days
实施例5-3Example 5-3	15天15 days	实施例5-11Example 5-11	5天5 days
实施例5-4Example 5-4	8天8 days	实施例5-12Example 5-12	20天20 days
实施例5-5Example 5-5	10天10 days	对比例5-1Comparative example 5-1	30分钟30 minutes
实施例5-6Example 5-6	7天7 days	对比例5-2Comparative Example 5-2	1天1 day
实施例5-7Example 5-7	18天18 days	对比例5-3Comparative Example 5-3	3天3 days
实施例5-8Example 5-8	20天20 days

It can be seen from the test results in Table 5-1 that the micro-nanocellulose composites prepared in Examples 5-1 to 5-12 can effectively strip the raw materials to the nanometer scale and at least stably disperse in the organic solvent for a long time. More than 5 days. In the comparative examples 5-1 to 5-2, the pure aqueous solution and the aqueous solution of dimethylformamide could not be used for urea-assisted peeling, and the micro-nanocellulose composite had a large particle size, and the dispersion rapidly precipitated.

It can be seen from the comparison of Examples 5-1 to 5-12 and Comparative Examples 5-1 to 5-2 that, in the preparation method described in the present application, urea can initially be used for graphite raw materials and/or lignin-containing cellulose raw materials. Peeling to obtain a small amount of graphene and/or micro-nanolignin cellulose, and then peeling off the graphene to peel off the cellulose raw material containing lignin to obtain micro-nano lignocellulose, and peeling off the micro-nano lignocellulose The graphite raw material can be peeled off to obtain graphene. The two exfoliation effects promote each other to obtain a micro-nanocellulose composite having a smaller size. After replacing the urea solution with a pure aqueous solution and an aqueous solution of dimethylformamide, the graphite and the lignin-containing cellulose raw material could not be assisted and peeled off, and the prepared composite had a large particle size and poor suspension stability; Example 5 - It can be seen from the comparison of 1 to 5-12 and Comparative Example 5-3 that the micro-nanocellulose composite containing lignin has good dispersibility in an organic solvent and good compatibility with an organic solvent.

It can be seen from the test results of Examples 5-11 and the remaining examples that the urea aqueous solution can obtain micro-nanocellulose (less than 200 nm) having a smaller diameter at 72 to 100 ° C, and its stability in dichloromethane. The dispersion time is more than one week.

The present application describes the micro-nanolignin cellulose of the present application and its preparation method and use by the above examples, but the present application is not limited to the above embodiments, that is, it does not mean that the present application must be implemented by relying on the above embodiments.

Claims

A micro-nanolignin cellulose, wherein the micro-nanolignin cellulose contains a lignin structure, and the lignin is combined with cellulose in the form of hydrogen bonds and chemical bonds.
The micro-nanolignin cellulose according to claim 1, wherein the micro-nanolignin cellulose has a lignin content of 10 to 35 wt%, optionally 25 to 28%.
The micro-nano lignocellulose according to claim 1 or 2, wherein the micro-nanolignin cellulose has a diameter of 5 to 250 nm and a length of more than 2 μm;

Optionally, the micro-nano lignocellulose has a diameter of 20-800 nm and an aspect ratio ≥50;

Optionally, the micro-nano lignocellulose has a diameter of 5-180 nm and an aspect ratio ≥200.
The method for producing micro-nanolignin cellulose according to any one of claims 1 to 3, wherein the method comprises the following steps:

(1) adding a cellulose raw material containing lignin to any solvent selected from the group consisting of an organic solvent, a hot aqueous urea solution or water at 50 ° C or higher to obtain a raw material dispersion;

(2) the raw material dispersion obtained in the step (1) is subjected to mechanical pretreatment for peeling and grinding to obtain a pretreated product;

(3) The pretreated product obtained in the step (2) is subjected to high pressure homogenization using a high pressure homogenizer to obtain a dispersion of the micro nano lignin cellulose.
The production method according to claim 4, wherein the organic solvent in the step (1) is an organic solvent having a boiling point higher than 72 ° C; and the organic solvent is heated before the cellulose raw material containing lignin is added to the organic solvent. To 72-128 ° C;

The temperature of the aqueous urea solution in step (1) is greater than or equal to 72 ° C and less than 100 ° C;

Optionally, the aqueous urea solution has a concentration of 0.1 to 10 mol/L.
The preparation method according to claim 4 or 5, wherein the temperature of the water above 50 ° C in the step (1) is ≥ 70 ° C, and the temperature of the water may be selected to be below the boiling point of water, optionally 70-80 °C, optional 70-75 ° C;

Optionally, the lignin-containing cellulose raw material in the step (1) is a residue obtained by completely extracting hemicellulose or partially extracting hemicellulose from a plant material;

Optionally, the plant material comprises any one of forest trees, crops, agricultural and forestry waste, or a combination of at least two;

Optionally, the lignin-containing cellulosic material comprises agricultural waste such as furfural residue, xylose residue, unbleached wood pulp, unbleached straw pulp, twigs, bark, wood shavings, roots, sawdust and straw. Any one or a combination of at least two; any one or a combination of at least two of optional alfalfa slag, xylose residue, unbleached wood pulp, unbleached straw pulp, and straw agricultural waste;

Optionally, the lignin-containing cellulose raw material has a lignin content of 10-30% by weight;

Optionally, the lignin-containing cellulose raw material has a cellulose content of 65 wt% or more;

Optionally, the lignin-containing cellulose raw material further contains hemicellulose;

Optionally, the lignin-containing cellulose raw material has a hemicellulose content of ≤10 wt%;

Optionally, the organic solvent is ethanol, isopropanol, n-butanol, tert-butanol, butanone, formamide, acetamide, N,N-dimethylformamide, N,N-dimethyl B. Any one or at least two of amide, aniline, benzene, toluene, xylene, chlorobenzene, octane, dimethyl sulfoxide, dioxane, ethyl acetate, acetonitrile, pyridine or carbon tetrachloride combination;

Optionally, the concentration of the cellulose raw material containing lignin in the raw material dispersion obtained in the step (1) is 1% by weight to 20% by weight, optionally 3-10% by weight, and optionally 5wt% to 10% by weight;

Optionally, the mechanical pretreatment of step (2) includes any one or a combination of at least two of ball milling, disc grinding or sanding, optionally sanding;

Optionally, the number of cycles of the mechanical pretreatment is greater than or equal to 1 time;

Alternatively, when sanding is used, the number of cycles of the sand mill is 1-3 times, the diameter of the sanded product is 180-1000 nm, the number of cycles of the sand mill is ≥5 times, and the diameter of the sanded product is 80. -200nm;

Optionally, when disc grinding and/or ball milling is used, the number of cycles is greater than or equal to 10 times, and optionally 12 or more times;

Optionally, when the raw material dispersion obtained in the step (1) is subjected to mechanical pretreatment for stripping and grinding as described in the step (2), the temperature of the raw material dispersion liquid is not higher than the boiling point of the solvent in the raw material dispersion liquid;

Optionally, when the solvent in the step (1) is a hot aqueous urea solution, the raw material dispersion obtained in the step (1) is subjected to mechanical pretreatment for stripping and grinding, and the raw material is dispersed. The liquid temperature is greater than or equal to 72 ° C and less than 100 ° C;

Optionally, when the solvent in the step (1) is water at 50° C. or higher, the raw material dispersion obtained in the step (1) is subjected to mechanical pretreatment for peeling and grinding, and the raw material is kept as described in the step (2). The temperature of the dispersion is 70-80 ° C;

Optionally, the pressure of the high pressure homogenization in the step (3) is 50-170 MPa, optionally 60-80 MPa;

Optionally, the number of cycles of the high pressure homogenization is 3-7 times;

Optionally, the high pressure homogenization process maintains the temperature not higher than the boiling point of the solvent in the pretreatment product obtained in the step (2);

Optionally, when the solvent in the step (1) is a hot aqueous urea solution, the high temperature homogenization in the step (3) is maintained at a temperature of 72 ° C or more and less than 100 ° C;

Optionally, when the solvent in step (1) is water above 50 ° C, the high temperature homogenization process in step (3) is maintained at a temperature of 70-80 ° C;

Optionally, the content of the micro-nano lignocellulose in the micro-nano lignocellulose dispersion is 0.1-18%;

Optionally, after step (3), performing step (4): removing the solvent of the dispersion of the micro-nano lignocellulose to obtain micro-nanolignin cellulose;

Optionally, the method of “removing a solvent of the dispersion of the micro-nano lignocellulose to obtain micro-nanolignin cellulose” includes any one of a combination of filtration, centrifugation, and drying, or a combination of at least two;

Optionally, the method of “removing the solvent of the dispersion of the micro-nano lignocellulose to obtain micro-nano lignocellulose” is carried out by filtration or centrifugation, and then the filter residue is dried to obtain micro-nanolignin fiber. Prime

Optionally, the drying comprises any one or a combination of at least two of spray drying, freeze drying and supercritical drying;

Optionally, the micro-nanolignin cellulose comprises a micro-nano lignocellulose powder or a micro-nano lignocellulose film;

Optionally, the post treatment comprises any one or a combination of at least two of filtration, washing, spray drying, and coating film formation.
A micro-nanocellulose composite, wherein the micro-nanocellulose composite comprises the micro-nano lignocellulose according to any one of claims 1 to 3, and dispersed in micro-nanolignin cellulose. Graphene material.
The micro-nanocellulose composite according to claim 7, wherein the content of the graphene material is 15 wt% or less, alternatively 5 wt% or less, alternatively 1 wt% or less of the micro-nanolignin cellulose.
The micro-nanocellulose composite according to claim 7 or 8, wherein the micro-nanocellulose composite has a length of ≥ 1 μm, a diameter of 4 to 200 nm, and an aspect ratio of 100 to 500;

Optionally, the graphene material has a thickness of < 20 nm, optionally 3-10 nm.
A method of preparing a micro-nanocellulose composite according to any one of claims 7-9, wherein the method comprises the steps of:

(I) dispersing the cellulose raw material containing lignin and the graphene material in water, and uniformly mixing to obtain a dispersion;

(II) pre-stripping the dispersion by mechanical force to obtain a pre-separation product dispersion;

(III) The pre-stripped product dispersion is homogenized by a high-pressure homogenizer to obtain a micro-nanocellulose composite dispersion.
The preparation method according to claim 10, wherein the graphene material of the step (I) has an average sheet thickness of ≤ 20 nm, optionally 3-10 nm.
The production method according to claim 10 or 11, wherein the concentration of the lignin-containing cellulose raw material and the graphene material in the dispersion obtained in the step (I) is 0.1% by weight to 15% by weight, and optionally 5% by weight. -7wt%;

Optionally, the lignin-containing cellulose raw material in the step (I) is a residue obtained by completely extracting hemicellulose or partially extracting hemicellulose from a plant material;

Optionally, the plant material comprises any one or a combination of at least two of forest trees, crops, and agricultural and forestry wastes;

Optionally, the lignin-containing cellulosic material comprises any one or a combination of at least two of furfural residue, xylose residue, unbleached wood pulp, unbleached straw pulp, and straw agricultural waste;

Optionally, the lignin-containing cellulose raw material has a lignin content of 10-30% by weight and a cellulose content of 65% or more;

Optionally, the lignin-containing cellulose raw material further contains hemicellulose;

Optionally, the lignin-containing cellulose raw material has a hemicellulose content of ≤10 wt%;

Optionally, the graphene material is prepared by a mechanical stripping method, a redox method, a thermal cracking method, an intercalation stripping method, a chemical vapor deposition method, a liquid phase stripping method or a biomass hydrothermal carbonization method;

Optionally, the graphene material is added in an amount of 10 wt% or less, optionally 5 wt% or less, alternatively 1 wt% or less, of the lignin-containing cellulose raw material;

Optionally, the mechanical force pre-peeling of step (II) includes any one of ultrasonic peeling, ball peeling, disc peeling, sanding peeling, and grinding peeling;

Optionally, the mechanical force pre-peeled product has a diameter of 200-1500 nm;

Optionally, the homogeneous pressure in the step (III) is 50-150 MPa, optionally 60-80 MPa;

Optionally, the number of times of homogenization is 3-10 times, optionally 3-7 times;

Optionally, after step (III), performing step (IV): post-treating the micro-nanocellulose composite dispersion to obtain a micro-nanocellulose composite powder;

Optionally, the post treatment comprises any one or a combination of at least two of washing, grinding, and spray drying.
A method of preparing a micro-nanocellulose composite according to any one of claims 7-9, wherein the method comprises the steps of:

(a) adding a graphite raw material and a cellulose raw material containing lignin to the aqueous urea solution to obtain a mixed raw material dispersion;

(b) mechanically separating the mixed raw material dispersion to obtain a micro-nanocellulose composite dispersion;

Alternatively, the solvent of the micro-nanocellulose composite dispersion is removed to obtain a micro-nanocellulose composite.
The preparation method according to claim 13, wherein in the aqueous urea solution of the step (a), the ratio of the mass of the urea to the sum of the mass of the graphite raw material and the cellulose raw material containing lignin is ≤1:3, optionally 0.01: 1-1:1.
The preparation method according to claim 13 or 14, wherein the aqueous urea solution has a temperature of 72-100 ° C, optionally 80-90 ° C;

Optionally, in the mixed raw material dispersion obtained in the step (a), the sum of the concentration of the graphite raw material and the lignin-containing cellulose raw material is 0.1-20% by weight, optionally 8-10% by weight;

Optionally, the mass ratio of the graphite raw material and the lignin-containing cellulose raw material is 1:10-10:1;

Optionally, the lignin-containing cellulose raw material is a residue obtained by completely extracting hemicellulose or partially extracting hemicellulose from a plant material;

Optionally, the plant material comprises any one or a combination of at least two of forest trees, crops, and agricultural and forestry wastes;

Optionally, the lignin-containing cellulosic material comprises any one or a combination of at least two of furfural residue, xylose residue, unbleached wood pulp, unbleached straw pulp, and straw agricultural waste;

Optionally, the lignin-containing cellulose raw material has a lignin content of 10-30% by weight and a cellulose content of 65% or more;

Optionally, the lignin-containing cellulose raw material further contains hemicellulose;

Optionally, the lignin-containing cellulose raw material has a hemicellulose content of ≤10 wt%;

Optionally, the graphite raw material comprises any one or a combination of at least two of expanded graphite, flake graphite, and graphite oxide;

Optionally, the mechanical peeling of step (b) includes any one or a combination of at least two of ultrasonic peeling, ball peeling, disc peeling, sanding peeling, high pressure homogenizing peeling, high pressure micro jet stripping, and grinding stripping. ;

Optionally, the method of “removing the solvent of the micro-nanocellulose composite dispersion” includes any one or a combination of at least two of filtration, centrifugation, and drying;

Optionally, the method of “removing the solvent of the micro-nanocellulose composite dispersion” is followed by filtration separation or centrifugation, and the filter residue is dried to obtain a micro-nanocellulose composite;

Optionally, the drying comprises any one or a combination of at least two of spray drying, freeze drying and supercritical drying;

Optionally, the micro-nanocellulose composite has a diameter of 5-180 nm and an aspect ratio ≥200; and the graphene material has a particle diameter of 0.1-50 μm.
The use of the micro-nanolignin cellulose according to any one of claims 1 to 3, wherein the micro-nano lignocellulose is used for textile materials, medical materials, high-performance additives, adsorbent materials, food packaging materials Or the preparation of composite materials.