CN114561827A

CN114561827A - Full-biomass-based wax emulsion waterproof coating and preparation method and application thereof

Info

Publication number: CN114561827A
Application number: CN202210180360.9A
Authority: CN
Inventors: 王小慧; 王玉园; 阚立军
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2022-02-25
Filing date: 2022-02-25
Publication date: 2022-05-31
Anticipated expiration: 2042-02-25
Also published as: CN114561827B

Abstract

The invention belongs to the field of waterproof material preparation, and provides a full biomass-based wax emulsion waterproof coating as well as a preparation method and application thereof. The amphiphilic derivative prepared by natural fatty acid modified biomass polysaccharide is used for constructing self-assembled nano micelles stably dispersed in water, and the amphiphilic biomass micelles are used for realizing water phase dispersion and emulsification of various biological waxes to obtain uniform and stable water-based wax emulsion. The water-based wax emulsion can act on substrates such as paper, paperboard, pulp molding and the like in various modes such as spraying, blade coating, dipping and the like, so that the high-efficiency water resistance of the paper-based material is realized. The raw materials of the invention are all from natural biomass resources, the preparation process does not involve the use of any harmful chemicals or organic solvents, the operation is simple, the invention is suitable for industrial continuous production and application, and the prepared biomass-based wax emulsion can be stably stored for a long time, is green and nontoxic, has low price and can be regenerated, and has good biocompatibility, food contact safety and environmental friendliness.

Description

Full-biomass-based wax emulsion waterproof coating and preparation method and application thereof

The technical field is as follows:

the invention belongs to the field of waterproof material preparation, and relates to a full biomass-based wax emulsion waterproof coating, and a preparation method and application thereof.

Background art:

paper-based packaging materials such as paper, paperboard, pulp molding and the like are important choices for replacing disposable plastic products, but paper-based materials with cellulose as a main component have poor barrier property as the packaging materials due to the hydrophilicity of cellulose molecules, and have remarkably reduced mechanical strength after being wetted after absorbing water, so that the improvement of the water resistance of wood fiber materials is particularly important.

At present, means for improving the waterproof performance of paper packaging materials mainly comprise a waterproof coating and a composite waterproof layer. The composite waterproof layer is generally made by combining a paper material with a plastic material, a film material, etc., so as to make the paper material waterproof. Such as the existing polyethylene-coated paper laminate, which has excellent mechanical strength and water resistance. However, for paper/polymer composites prepared based on this technique, the polyethylene film layer is difficult to separate from the cellulosic material, making it impossible to recycle it and degrade it in the environment.

The formation of a water repellent coating on a material surface by spraying or dipping is considered as an economically effective means for imparting hydrophobicity to the material. Currently, low surface energy materials (such as fluorine-containing polymers and siloxane) are generally used for waterproof coatings, and the fluorine-containing polymers are mainly used. However, the fluorine-containing polymer has biological toxicity, the siloxane is relatively less toxic, but the cost is high, and the organic solvent which is often used for using the materials greatly limits the practical application of the materials. Therefore, the biomass material with wide source, low cost, nature and no toxicity is selected as the waterproof coating for modification, and the waterproof coating has good application prospect.

The wax has main component of ester formed by long chain fatty acid and fatty alcohol, and other components such as free long chain fatty acid and alcohol, long chain alkane, etc. also have certain content. High-grade fatty acid, alcohol and the like in the wax form a crystallization area to a certain degree, a more compact structure is formed, the water vapor resisting capability can be well realized, and the material is endowed with excellent waterproof performance. Paraffin is the most common type of wax used for water repellent treatment, and coating paraffin on the surface of a fibrous material can prevent the cellulose material from absorbing moisture. However, paraffin is derived from petroleum, coal, etc., and is a non-renewable resource, which limits its applications.

Thus, in recent years, biological waxes derived from abundant, renewable plant or animal resources have been the focus of research and application. For example, in US 20190249369a1, rice bran wax and sugar cane wax of vegetable origin are used, and surfactants such as stearic acid are added to improve adhesion to the underlying material. The waterproof paper base material prepared by the hot extrusion process can be economically recycled, and the waterproof coating compounded by the two vegetable waxes can also be used as a container of hot drinks. However, for practical applications, the wax extrusion process is relatively complex. In contrast, wax emulsion is easier to popularize for industrial application, but in the prior art of forming wax emulsion at present, the problems of large viscosity, poor emulsion stability, more addition amount of emulsifier and the like exist, so that it is very important to find an emulsifier which is wide in source, green and nontoxic and has excellent emulsifying effect.

The invention content is as follows:

in order to overcome the defects of the prior art, the invention aims to provide the preparation method of the full-biomass wax emulsion waterproof coating, which does not relate to fluorine-containing chemicals or toxic reagents, is simple to operate, is non-toxic and environment-friendly and is suitable for industrial continuous production and application.

The invention also aims to provide the full biomass wax emulsion waterproof coating prepared by the method.

The invention further aims to provide application of the full biomass wax emulsion waterproof coating in preparation of waterproof paper base materials.

The technical scheme is as follows:

a preparation method of a full biomass wax emulsion waterproof coating comprises the following steps:

(1) preparation of the biomass-based derivative self-assembled micelle: adding biomass and fatty acid into a solvent, and stirring and dissolving to obtain a mixed solution; then adding a catalyst into the mixed solution, stirring, and after the reaction is finished, pouring the reaction mixture into an anti-solvent for precipitation to obtain the biomass-based amphiphilic derivative; dissolving the biomass-based amphiphilic derivative in a good solvent, and dialyzing in water to obtain a biomass-based nano micelle aqueous dispersion;

(2) preparation of wax emulsion: and (2) mixing the wax and the biomass-based micelle aqueous dispersion in the step (1), heating to a temperature above the melting point of the wax, stirring until the wax and the biomass-based micelle are uniformly mixed, and emulsifying to obtain the full-biomass wax emulsion waterproof coating.

Preferably, in step (1), the biomass may be one or more selected from cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, dialdehyde cellulose, hemicellulose, chitosan, carboxymethyl chitosan, starch, cationic starch and dialdehyde starch.

Preferably, in the step (1), the mass percentage concentration of the biomass in the solvent is 1 wt% to 10 wt%.

Preferably, in the step (1), the fatty acid may be one or more selected from butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, sebacic acid, lauric acid, oleic acid, linoleic acid, palmitic acid, linolenic acid and stearic acid.

Preferably, in the step (1), the mass ratio of the biomass to the fatty acid is (0.5-5): 5.

preferably, the solvent in step (1) may be selected from at least one of the following: ionic liquid, eutectic solvent and organic solvent. Preferably, the ionic liquid is 1-butyl-3-methylimidazole chloride, and the organic solvent is dimethyl sulfoxide (DMSO).

Preferably, in step (1), the catalyst may be selected from one or two or more of the following compositions: n, N-dimethyl-4-aminopyridine (DMAP), Dicyclohexylcarbodiimide (DCC), N' -Diisopropylcarbodiimide (DIC).

Preferably, in step (1), the antisolvent may be selected from: any one of methanol, ethanol, isopropanol, acetone, N-dimethylformamide, diethyl ether, water, etc.

Preferably, in the step (1), the temperature for stirring and dissolving is 25-100 ℃, and the stirring time is 0.5-3 hours.

Preferably, in the step (1), the adding of the catalyst is performed for stirring for 1-24 hours at normal temperature. Preferably 6-24 h.

Preferably, in the step (1), the rotation speed of the centrifugation is 4000-6000 rpm, the time is 5-30 min, the drying temperature is 40-80 ℃, and the time is 6-24 h.

Preferably, the wax in step (2) can be selected from one or more of the following: a natural source of vegetable wax or animal wax, more preferably at least one of beeswax, carnauba wax, candelilla wax, rice bran wax, sunflower wax, sugar cane wax, soybean wax, coconut wax, and fruit wax.

Preferably, the mass ratio of the wax to the biomass-based nanomicelle aqueous dispersion in the step (2) is (0.05:10) to (2: 10). The mass fraction of the biomass-based nano-micelle in the biomass-based nano-micelle dispersion liquid is 0.8 wt% -3 wt%.

Preferably, the emulsification treatment in step (2) may be at least one of the following: ultrasonic and homogenizing emulsifying with emulsifier. The ultrasonic power is 40-80w, the time is 5-30 min, and the stirring speed of the homogeneous emulsifier is 10000-20000 rpm.

The application of the full biomass wax emulsion waterproof coating in preparing a waterproof paper base material.

The application specifically comprises the steps of applying the full biomass wax emulsion waterproof coating on the surface of a paper-based packaging material, and then carrying out heat treatment to obtain the waterproof paper-based material.

The paper-based packaging material is molded by paper, paperboard or paper pulp; the coating application mode is selected from at least one of the following modes: spraying, coating and laminating. The heat treatment temperature is 60-150 ℃, and the heat treatment time is 15-120 min.

Compared with the prior art, the invention has the following advantages and effects:

(1) the method selects natural wax as a wax raw material, utilizes the biomass-based derivative micelle as an emulsifier, and can obtain the stably dispersed aqueous wax emulsion under the condition of adding a small amount of the emulsifier. The raw materials are wide in source, simple and easy to obtain, and low in cost.

(2) The method sprays the waterproof coating on the surface of the substrate in the form of emulsion, does not use organic solvent, is green and environment-friendly, has simple coating application process, and is easy for industrial production.

(3) The obtained waterproof substrate has good waterproof effect, is a full biomass base, is natural, non-toxic, renewable, can be contacted with edible products, and can be naturally degraded.

Description of the drawings:

fig. 1 is a graph showing the particle size distribution of biomass-based micelles in example 1.

FIG. 2 is an electron microscope photograph of the wax emulsion of example 1.

Fig. 3 is a diagram showing the water-repellent effect of the water-repellent paper obtained in example 1.

Fig. 4 is a diagram showing the water-repellent effect of the water-repellent pulp-molded dinner plate obtained in example 2.

FIG. 5 is a graph showing the effect of the wax emulsion obtained in comparative example 1.

The specific implementation mode is as follows:

the present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto. For process parameters not specifically noted, reference may be made to conventional techniques.

Example 1:

(1)1g of hemicellulose and 5g of lauric acid were added to 100ml of DMSO, stirred at 95 ℃ for 1.5 hours to completely dissolve them, and then cooled to room temperature. Subsequently, 0.3g of DMAP and 1.5g of DCC as catalysts were added, and the mixture was stirred at room temperature for 24 hours. After the reaction is finished, precipitating by using absolute ethyl alcohol, centrifuging at 4000rpm for 5min, collecting the precipitate, washing by using the absolute ethyl alcohol for 3 times, and drying at 60 ℃ to obtain the hemicellulose-derived laurate. The resulting product was dissolved in DMSO at a concentration of 1 wt%, and dialyzed in water to obtain hemicellulose laurate micelles.

When the particle size is measured by Dynamic Light Scattering (DLS), as shown in fig. 1, it can be seen that the micelle has only one peak of particle size distribution and has narrow distribution, indicating that the micelle is single and uniformly distributed and has an average particle size of about 70 nm.

(2) Heating and mixing 3g of beeswax and 30ml of 1 wt% hemicellulose amphiphilic micelle at 75 ℃, stirring at 500rpm for 10min, and performing ultrasonic treatment for 15min to obtain uniformly dispersed wax emulsion.

Fig. 2 shows that the micelle nanoparticles are uniformly distributed on the surface of the wax emulsion droplets to form a space barrier, which effectively prevents the wax emulsion from aggregating, indicating the successful preparation of the wax emulsion.

And (3) spraying the wax emulsion obtained in the step (2) on the surface of the cellulose base paper by a spray gun, wherein the distance between the spray gun and the substrate is 15-25 cm, the number of spraying layers is 3-5, and carrying out heat treatment on the treated paper at 75 ℃ for 15-120 min to obtain the waterproof paper.

As shown in fig. 3, several different liquid drops are selected, which maintain a hydrophobic state on the surface of the waterproof paper, and the paper is not wetted, showing excellent waterproofness.

Example 2

(1)2g of cellulose and 5g of oleic acid were dissolved in 100ml of an ionic liquid (1-butyl-3-methylimidazole chloride) and stirred at 80 ℃ for 0.5h to completely dissolve the cellulose and the oleic acid. Then, 2ml of DIC as a catalyst was added thereto, and the mixture was stirred at room temperature for 24 hours. After the reaction is finished, acetone is used for precipitation, the mixture is centrifuged at 4000rpm for 5min, the precipitate is collected, then acetone and absolute ethyl alcohol are used for washing for 3 times, and then drying is carried out at 60 ℃ to obtain the cellulose-based oleate. Dissolving the obtained product in DMSO, and dialyzing in water to obtain the cellulose-based amphiphilic micelle.

(2)3g of palm wax and 50ml of 1 wt% cellulose-based amphiphilic micelle are heated, stirred and mixed at 100 ℃, and then the homogeneous emulsifier is stirred at 20000rpm for 5min to obtain the evenly dispersed wax emulsion.

And (3) spraying the wax emulsion obtained in the step (2) on the surface of the paper pulp molding dinner plate, wherein the distance between a spray gun and a substrate is 15 cm, the number of spraying layers is 3-5, and the treated dinner plate is subjected to heat treatment at 100 ℃ for 15-120 min to obtain the waterproof dinner plate. As shown in fig. 4, the resulting pulp molded dishes exhibited excellent hydrophobicity and the dishes were not wetted by water.

Example 3

(1) Dissolving 1g of chitosan and 5g of linoleic acid in 100ml of ionic liquid (1-allyl-3-methylimidazole chloride), stirring at 90 ℃ for 3 hours to completely dissolve the chitosan and the linoleic acid, and then cooling to room temperature. 0.3g of DMAP catalyst and 1ml of DIC are subsequently added and the mixture is stirred at room temperature for 12 hours. After the reaction is finished, precipitating by using absolute ethyl alcohol, centrifuging at 4000rpm for 5min, collecting the precipitate, washing by using the absolute ethyl alcohol for 3 times, and drying at 80 ℃ to obtain the chitosan derivative linoleate. Dissolving the obtained product in DMSO, and dialyzing in water to obtain the chitosan-based amphiphilic micelle.

(2) 2g of candelilla wax and 30ml of 1 wt% chitosan-based amphiphilic micelle are heated to 75 ℃, mixed and stirred at 500rpm for 10min, and then the mixture is subjected to ultrasonic treatment for 15min to obtain evenly dispersed wax emulsion.

And (3) spraying the wax emulsion obtained in the step (2) on the surface of the cellulose base paper by a spray gun, wherein the distance between the spray gun and the substrate is 15 cm, the number of spraying layers is 3-5, and carrying out heat treatment on the treated paper at 70 ℃ for 30min to obtain the waterproof paper.

The liquid drops keep a hydrophobic state on the surface of the waterproof paper, so that the paper cannot be wetted and excellent waterproofness is realized.

Comparative example 1

(1)1g of hemicellulose and 0.5g of lauric acid were added to 100ml of DMSO, and they were completely dissolved by stirring at 95 ℃ for 1.5 hours, followed by cooling to room temperature. Subsequently, 0.3g of DMAP and 1.5g of DCC as catalysts were added, and the mixture was stirred at room temperature for 24 hours. After the reaction is finished, precipitating by using absolute ethyl alcohol, centrifuging at 4000rpm for 5min, collecting the precipitate, washing by using the absolute ethyl alcohol for 3 times, and drying at 60 ℃ to obtain the hemicellulose-derived laurate. The resulting product was dissolved in DMSO at a concentration of 1 wt%, and dialyzed in water to obtain hemicellulose laurate micelles.

(2) Heating and mixing 3g of beeswax and 30ml of 0.5 wt% hemicellulose amphiphilic micelle at 75 ℃, stirring at 500rpm for 10min, and performing ultrasonic treatment for 15min to obtain a wax emulsion with poor dispersibility and more precipitates, as shown in figure 5.

Claims

1. A preparation method of a full biomass wax emulsion waterproof coating is characterized by comprising the following steps:

(1) preparation of the biomass-based derivative self-assembled micelle: adding biomass and fatty acid into a solvent, and stirring and dissolving to obtain a mixed solution; then adding a catalyst into the mixed solution, and pouring the reaction mixture into an anti-solvent for precipitation after the reaction is finished to obtain the biomass-based amphiphilic derivative; dissolving the biomass-based amphiphilic derivative in a good solvent, and dialyzing in water to obtain a biomass-based nano micelle aqueous dispersion;

2. The production method according to claim 1, characterized in that: in the step (1), the biomass is selected from one or more than two of cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, dialdehyde cellulose, hemicellulose, chitosan, carboxymethyl chitosan, starch, cationic starch and dialdehyde starch; the fatty acid is selected from one or more of butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, sebacic acid, lauric acid, oleic acid, linoleic acid, palmitic acid, linolenic acid and stearic acid.

3. The method of claim 1, wherein: in the step (1), the mass percentage concentration of the biomass in the solvent is 0.5 wt% -10 wt%; the mass ratio of the biomass to the fatty acid is (0.5-5): 5.

4. the method of claim 1, wherein: the solvent in the step (1) is selected from at least one of the following solvents: ionic liquid, eutectic solvent and diorgano solution; the catalyst is selected from one or more of the following compositions: n, N-dimethyl-4-aminopyridine, dicyclohexylcarbodiimide, N' -diisopropylcarbodiimide; the antisolvent is selected from: any one of methanol, ethanol, isopropanol, acetone, N-dimethylformamide, diethyl ether and water.

5. The production method according to claim 1, characterized in that: the wax in the step (2) is natural plant wax or animal wax; the mass ratio of the wax to the biomass-based nano micelle aqueous dispersion in the step (2) is (0.05:10) - (2:10), and the mass fraction of the biomass-based nano micelle in the biomass-based nano micelle aqueous dispersion is 0.6 wt% -3 wt%.

6. The method of claim 1, wherein: the wax in the step (2) is at least one of beeswax, palm wax, carnauba wax, candelilla wax, rice bran wax, sunflower wax, sugar cane wax, soybean wax, coconut wax and fruit wax.

7. The production method according to claim 1, characterized in that: the emulsification treatment in the step (2) is specifically emulsification by ultrasonic and/or homogeneous emulsifying agents; the temperature of the heat treatment in the step (3) is 60-150 ℃, and the time of the heat treatment is 15-120 min.

8. An all-biomass wax emulsion waterproof coating prepared by the method of any one of claims 1 to 7.

9. Use of the all biomass wax emulsion water repellant coating of claim 8 in the preparation of a water repellant paper base material.

10. The use according to claim 9, characterized in that it is in particular the application of a full biomass wax emulsion waterproofing coating on the surface of a paper based packaging material, followed by a heat treatment to obtain a waterproofing paper based material.