CN114561827B - A kind of all-biomass-based wax emulsion waterproof coating and its preparation method and application - Google Patents

Abstract

The invention belongs to the field of waterproof material preparation, and provides a full biomass-based wax emulsion waterproof coating, and a preparation method and application thereof. The amphiphilic derivative prepared by modifying biomass polysaccharide with natural fatty acid is used for constructing self-assembled nano-micelle which is stably dispersed in water, and the amphiphilic biomass micelle is used for realizing water-phase dispersion and emulsification of various biological waxes, so that uniform and stable aqueous wax emulsion is obtained. The aqueous wax emulsion can act on substrates such as paper, paperboard, pulp molding and the like in various modes such as spraying, knife coating, dipping and the like, so that the high-efficiency waterproof performance of paper-based materials 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 is renewable, and has good biocompatibility, food contact safety and environmental friendliness.

Description

A kind of all-biomass-based wax emulsion waterproof coating and its preparation method and application

Technical field:

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

Background technique:

Paper-based packaging materials such as paper, cardboard, and pulp molding are important choices to replace disposable plastic products, but paper-based materials with cellulose as the main component have poor barrier properties as packaging materials due to the hydrophilicity of cellulose molecules , and get wet after absorbing water, the mechanical strength is significantly reduced, so it is particularly important to improve the water resistance of lignocellulosic materials.

At present, the means to improve the waterproof performance of paper packaging materials mainly include waterproof coating and composite waterproof layer. The composite waterproof layer is usually a composite of plastic, film and other materials with paper materials to make it waterproof. Like the existing polyethylene coated paper laminate, it has excellent mechanical strength and water resistance. But for paper/polymer composites prepared based on this technique, the polyethylene film layer is difficult to separate from the cellulose material, making it impossible to be recycled and degraded in the environment.

Forming a waterproof coating on the surface of a material by spraying or soaking is considered to be an economical and effective measure to endow the material with hydrophobicity. At present, waterproof coatings usually use low surface energy materials (such as fluoropolymers, siloxanes), mainly fluoropolymers. However, fluoropolymers are biologically toxic, and siloxane is relatively less toxic, but the cost is high, and these materials often need to use organic solvents, which greatly limit their practical applications. Therefore, the selection of biomass materials with a wide range of sources, low cost, and natural non-toxicity as waterproof coating decoration has a good application prospect.

Waxy, the main component is an ester formed by long-chain fatty acids and fatty alcohols, and other components such as free long-chain fatty acids and alcohols, long-chain alkanes, etc. also have a certain content. Higher fatty acids and alcohols in the wax form a certain degree of crystallization area, forming a more compact structure, which can well insulate water vapor and endow the material with excellent waterproof performance. Paraffin wax is the most common type of wax used for waterproofing. Coating paraffin wax on the surface of the fiber material can prevent the cellulose material from absorbing water. However, paraffin is derived from petroleum, coal, etc., and is a non-renewable resource, which limits its application.

Therefore, in recent years, biowaxes derived from abundant and renewable plant or animal resources have become a research and application hotspot. For example, in US 20190249369A1, plant-derived rice bran wax and sugarcane wax are used, and a surfactant such as stearic acid is added to improve its adhesion to the underlying material. Through the hot extrusion process, the prepared waterproof paper-based material can be economically recycled, and the waterproof coating compounded by the two kinds of vegetable waxes can also be used as a container for hot drinks. However, for practical applications, the wax extrusion process is relatively complicated. In contrast, wax emulsions are easier to promote for industrial applications. However, in the current prior art of forming wax emulsions, there are still problems such as high viscosity of wax emulsions, poor emulsion stability, and large amounts of emulsifiers. Therefore, a source of Wide range of emulsifiers that are green, non-toxic and have excellent emulsifying effects are very important.

Invention content:

In order to overcome the shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide a preparation method of an all-biomass wax emulsion waterproof coating, which does not involve fluorine-containing chemicals or toxic reagents, is simple to operate, non-toxic and environmentally friendly, and is suitable for industrial continuous production application.

Another object of the present invention is to provide the all-biomass wax emulsion waterproof coating prepared by the above method.

Another object of the present invention is to provide the application of the above-mentioned all-biomass wax emulsion waterproof coating in the preparation of waterproof paper-based materials.

Its technical scheme is as follows:

A preparation method for an all-biomass wax emulsion waterproof coating, comprising the following steps:

(1) Preparation of self-assembled micelles of biomass-based derivatives: adding biomass and fatty acids to the solvent, stirring and dissolving to obtain a mixed solution; then adding a catalyst to the mixed solution and stirring, after the reaction, the reaction The mixture is poured into an anti-solvent for precipitation to obtain a biomass-based amphiphilic derivative; the above-mentioned biomass-based amphiphilic derivative is dissolved in a good solvent, and the aqueous dispersion of biomass-based nano micelles is obtained by dialysis in water;

(2) Preparation of wax emulsion: After mixing the wax and the biomass-based micelles aqueous dispersion in step (1), heat to above the melting point of the wax, then stir until the wax and the biomass-based micelles are mixed evenly, after emulsification treatment Obtain the all-biomass wax emulsion waterproof coating.

Preferably, in step (1), the biomass can be selected from cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, dialdehyde fiber One or more of cellulose, hemicellulose, chitosan, carboxymethyl chitosan, starch, cationic starch, dialdehyde starch.

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

Preferably, in step (1), the fatty acid may be selected from butyric acid, valeric acid, caproic acid, heptanoic acid, octanoic acid, nonanoic acid, capric acid, sebacic acid, lauric acid, oleic acid, linoleic acid, palmitic acid One or more of linolenic acid, linolenic acid and stearic acid.

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

Preferably, the solvent in step (1) can be selected from at least one of the following: ionic liquids, deep eutectic solvents, and organic solvents. Preferably, the ionic liquid is 1-butyl-3-methylimidazole chloride, and the organic solvent is dimethylsulfoxide (DMSO).

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

Preferably, in step (1), the anti-solvent can be selected from any one of methanol, ethanol, isopropanol, acetone, N,N-dimethylformamide, ether, water and the like.

Preferably, in step (1), the stirring and dissolving temperature is 25-100° C., and the stirring time is 0.5-3 h.

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

Preferably, in step (1), the rotational speed of the centrifugation is 4000-6000 rpm, and the time is 5-30 minutes, and the temperature of the drying is 40-80° C., and the time is 6-24 hours.

Preferably, the wax in step (2) can be selected from one or more of the following: vegetable wax or animal wax from natural sources, more preferably beeswax, palm wax, carnauba wax, candelilla wax, rice bran wax, sunflower wax At least one of wax, sugarcane wax, soybean wax, coconut wax and fruit wax.

Preferably, the mass ratio of the wax in step (2) to the aqueous dispersion of biomass-based nano micelles 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 0.8wt-3wt%.

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

The application of the all-biomass wax emulsion waterproof coating in the preparation of waterproof paper-based materials.

The application is specifically to apply the all-biomass wax emulsion waterproof coating on the surface of the paper-based packaging material, followed by heat treatment to obtain the waterproof paper-based material.

The paper-based packaging material is paper, cardboard or pulp molding; the coating application method is selected from at least one of the following: spraying, coating, and laminating. The heat treatment temperature is 60-150° C., and the heat treatment time is 15-120 minutes.

Compared with prior art, the present invention has following advantage and effect:

(1) In this method, natural wax is selected as the wax raw material, and the biomass-derived micelles are used as the emulsifier. In the case of a small amount of emulsifier added, a water-based wax emulsion with stable dispersion can be obtained. The source of raw materials is extensive, easy to obtain, and low in cost.

(2) The method sprays the waterproof paint on the surface of the substrate in the form of emulsion, without the use of organic solvents, and is environmentally friendly, and the paint application process is simple and easy for industrial production.

(3) The obtained waterproof substrate has a good waterproof effect, is entirely biomass-based, is naturally non-toxic, renewable, food-contactable, and naturally degradable.

Description of drawings:

Figure 1 is the particle size distribution of the biomass-based micelles in Example 1.

Fig. 2 is the electron micrograph of embodiment 1 wax emulsion.

FIG. 3 is a diagram of the waterproof effect of the waterproof paper obtained in Example 1. FIG.

FIG. 4 is a waterproof effect diagram of the waterproof pulp molded dinner plate obtained in Example 2. FIG.

FIG. 5 is an effect diagram of the wax emulsion obtained in Comparative Example 1.

Detailed ways:

The present invention will be further described in detail below with reference to the examples and drawings, but the implementation of the present invention is not limited thereto. For the process parameters not specified in particular, it can be carried out with reference to conventional techniques.

Example 1:

(1) Add 1g hemicellulose and 5g lauric acid into 100ml DMSO, stir at 95°C for 1.5h to dissolve completely, and then cool to room temperature. Subsequently, catalyst 0.3g DMAP and 1.5g DCC were added and stirred at room temperature for 24 hours. After the reaction, precipitate with absolute ethanol, centrifuge at 4000rpm for 5 minutes to collect the precipitate, wash with absolute ethanol three times, and then dry at 60°C to obtain hemicellulose-derived laurate. The obtained product was dissolved in DMSO at a concentration of 1 wt%, and dialyzed in water to obtain hemicellulose laurate micelles.

Use dynamic light scattering (DLS) to measure its particle size, as shown in Figure 1, it can be seen that the micelles have only one particle size distribution peak, and the distribution is narrow, indicating that the micelles are single and uniformly distributed, and the average particle size About 70nm.

(2) Heat and mix 3g of beeswax and 30ml of 1wt% hemicellulose amphiphilic micelles at 75°C, stir at 500rpm for 10min, and ultrasonicate for 15min to obtain a uniformly dispersed wax emulsion.

It can be seen from Figure 2 that the micellar nanoparticles are evenly distributed on the surface of the wax emulsion droplets, forming a space barrier and effectively preventing the aggregation of the wax emulsion, indicating the successful preparation of the wax emulsion.

Spray the wax emulsion obtained in step (2) on the surface of cellulose base paper with a spray gun, the spray gun is 15-25 cm away from the base, and the number of sprayed layers is 3-5 layers. The treated paper is heat-treated at 75°C for 15-120 minutes to obtain waterproof paper.

As shown in Figure 3, several different droplets are selected, and they all maintain a hydrophobic state on the surface of the waterproof paper, and the paper will not be wetted, showing excellent water resistance.

Example 2

(1) Dissolve 2g of cellulose and 5g of oleic acid in 100ml of ionic liquid (1-butyl-3-methylimidazole chloride), stir at 80°C for 0.5h to dissolve completely. Then add catalyst 2ml DIC, stir at room temperature for 24 hours. After the reaction, precipitate with acetone, centrifuge at 4000 rpm for 5 minutes to collect the precipitate, wash with acetone and absolute ethanol three times, and then dry at 60°C to obtain cellulose-based oleate. The obtained product was dissolved in DMSO and dialyzed in water to obtain cellulose-based amphiphilic micelles.

(2) 3g of palm wax and 50ml of 1wt% cellulose-based amphiphilic micelles were heated and stirred at 100°C, and then stirred with a homogeneous emulsifier at 20,000rpm for 5min to obtain a uniformly dispersed wax emulsion.

Spray the wax emulsion obtained in step (2) on the surface of the pulp molded dinner plate, the spray gun is 15 cm away from the base, and the number of sprayed layers is 3 to 5 layers. The treated dinner plate is heat-treated at 100° C. for 15 to 120 minutes to obtain a waterproof dinner plate . As shown in Fig. 4, the obtained pulp molded dinner plate exhibited excellent hydrophobicity, and the plate would not be wetted by water.

Example 3

(1) 1g of chitosan and 5g of linoleic acid were dissolved in 100ml of ionic liquid (chlorinated-1-allyl-3-methylimidazole), stirred at 90°C for 3h to dissolve completely, and then cooled to room temperature. Subsequently, 0.3 g catalyst DMAP and 1 ml DIC were added, and stirred at room temperature for 12 hours. After the reaction, use absolute ethanol to precipitate, centrifuge at 4000 rpm for 5 minutes to collect the precipitate, wash with absolute ethanol three times, and then dry at 80° C. to obtain chitosan-derived linoleic acid ester. The obtained product was dissolved in DMSO and dialyzed in water to obtain chitosan-based amphiphilic micelles.

(2) Heat 2g of candelilla wax and 30ml of 1wt% chitosan-based amphiphilic micelles to 75°C, mix and stir, stir at 500rpm for 10min, and ultrasonicate for 15min to obtain a uniformly dispersed wax emulsion.

Spray the wax emulsion obtained in step (2) on the surface of the cellulose base paper through a spray gun, the spray gun is 15 cm away from the substrate, and the number of sprayed layers is 3 to 5 layers. The treated paper is heat-treated at 70°C for 30 minutes to obtain waterproof paper.

The liquid droplets remain in a hydrophobic state on the surface of the waterproof paper, and the paper will not be wetted, showing excellent water resistance.

Comparative example 1

(1) Add 1g of hemicellulose and 0.5g of lauric acid into 100ml of DMSO, stir at 95°C for 1.5h to dissolve completely, and then cool to room temperature. Subsequently, catalyst 0.3g DMAP and 1.5g DCC were added and stirred at room temperature for 24 hours. After the reaction, precipitate with absolute ethanol, centrifuge at 4000rpm for 5 minutes to collect the precipitate, wash with absolute ethanol three times, and then dry at 60°C to obtain hemicellulose-derived laurate. The obtained product was dissolved in DMSO at a concentration of 1 wt%, and dialyzed in water to obtain hemicellulose laurate micelles.

(2) 3g of beeswax and 30ml of 0.5wt% hemicellulose amphiphilic micelles were heated and mixed at 75°C, stirred at 500rpm for 10min, and ultrasonicated for 15min. The resulting wax emulsion had poor dispersion and more precipitation, as shown in Figure 5. Show.

Claims (6)

1. a kind of preparation method of full biomass wax emulsion waterproof coating is characterized in that comprising the following steps: (1) Preparation of self-assembled micelles of biomass-based derivatives: adding biomass and fatty acids to the solvent, stirring and dissolving to obtain a mixed solution; then adding a catalyst to the mixed solution, and pouring the reaction mixture Precipitate in an anti-solvent to obtain a biomass-based amphiphilic derivative; dissolve the above-mentioned biomass-based amphiphilic derivative in a good solvent, and obtain a biomass-based nanomicelle water dispersion by dialysis in water; The biomass is selected from cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, dialdehyde cellulose, hemicellulose, chitosan, One or more of carboxymethyl chitosan, starch, cationic starch, and dialdehyde starch; One or more of diacid, lauric acid, oleic acid, linoleic acid, palmitic acid, linolenic acid and stearic acid; the solvent is selected from at least one of the following: ionic liquid, deep eutectic solvent, organic Solvent; the catalyst is selected from one or more of the following compositions: N,N-dimethyl-4-aminopyridine, dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiyl Imine; the anti-solvent is selected from any one of methanol, ethanol, isopropanol, acetone, N,N-dimethylformamide, ether, and water; (2) Preparation of wax emulsion: Mix the wax and the aqueous dispersion of biomass-based micelles in step (1) and heat to above the melting point of the wax, then stir until the wax and biomass-based micelles are evenly mixed, and after emulsification treatment Obtain full biomass wax emulsion waterproof coating; The wax is at least one of beeswax, palm wax, candelilla wax, rice bran wax, sunflower wax, sugarcane wax, soybean wax, coconut wax and fruit wax; In step (1), the mass percent concentration of the biomass in the solvent is 0.5wt%-10wt%; the mass ratio of the biomass to the fatty acid is (0.5-5):5. 2. The preparation method according to claim 1, characterized in that: the wax in step (2) is vegetable wax or animal wax of natural origin; the wax in step (2) and the biomass-based nano-micelle water dispersion The mass ratio is (0.05:10)~(2:10), and the mass fraction of the biomass-based nanomicelles in the biomass-based nanomicelle dispersion is 0.6wt~3wt%. 3. The preparation method according to claim 1, characterized in that: the emulsification treatment in step (2) is emulsification by ultrasonic and/or homogeneous emulsifier. 4. An all-biomass wax emulsion waterproof coating is prepared by the method described in any one of claims 1 to 3. 5. the application of the all-biomass wax emulsion waterproof coating described in claim 4 in the preparation of waterproof paper-based materials. 6. The application according to claim 5, characterized in that the application is specifically applying the all-biomass wax emulsion waterproof coating on the surface of the paper-based packaging material, followed by heat treatment to obtain a waterproof paper-based material.

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