WO2023088018A1 - Aqueous coating having water-proof and oil-proof properties, preparation method therefor and application thereof - Google Patents

Abstract

Disclosed are an aqueous coating having water-proof and oil-proof properties, a preparation method therefor and an application thereof. The aqueous coating comprises the following components: a hydrophobic component selected from an oil-in-water Pickering emulsion; and an oil-proof component selected from one or more of natural polysaccharide substances and polyvinyl alcohol. The present invention solves the problems of the unavailability of a water-proof and oil-proof coating which is hydrophobic, waterproof, oil-proof, green, environment-friendly, safe, and applicable in a large scale.

Description

A kind of water-based paint with waterproof and oil-proof performance, its preparation method and application technical field

The invention relates to the technical field of hydrophobic and oil-proof paper. More specifically, it relates to a water-based paint with waterproof and oil-repellent performance, its preparation method and application.

Background technique

Paper-based materials are widely used and are expected to replace plastics due to their low-cost, renewable, readily available, and biodegradable properties. However, due to the porosity and hydrophilicity of paper-based materials, they have no barrier effect on gas, water, and oil, and their strength is severely reduced in high-humidity environments or when they encounter water, which greatly limits their further applications. Therefore, many methods are used to improve the water and oil repellency of paper materials to further expand its application range, such as: adding sizing agents in the papermaking process or coating the paper surface. These methods are mainly to improve the paper surface fiber The hydrophobicity also fills the pores between paper fibers.

At present, the commercial waterproof and oil-proof paper is mainly coated with a layer of plastic film on the surface of the paper substrate, also known as plastic coating. Polymers such as polypropylene, low-density polyethylene, polyvinyl chloride and polyethylene terephthalate are usually combined on the surface of the paper by coating or lamination. These polymer materials will form a dense structure on the surface of the paper. The film forms a barrier layer to prevent water and oil from contacting the paper, thereby achieving the effect of waterproof and oil-proof. Paper cups, paper boxes, and paper lunch boxes in daily life are almost all made by the above methods. However, on the one hand, the polymers on the surface of the paper products prepared by these methods are difficult to separate from the paper-based materials, which brings troubles to the recycling of paper-based materials, and on the other hand, their inability to be degraded will aggravate the problem of microplastics. In addition, fluorine compounds, which were first used in the field of paper oil repellency, have excellent hydrophobic and oleophobic properties due to their low surface tension, and the outward orientation of hydrophobic groups can form a barrier barrier, endowing paper-based materials with excellent water repellency Oil-resistant properties. However, fluorine-containing substances are not only expensive, but also have potential health hazards and environmental risks. Fluorinated substances with long carbon chains have been shown to cause cancer. In 2019, the United States announced a ban on the use of fluorinated chemicals in food packaging applications, as well as in cookware and food containers. Polysiloxane (especially polydimethylsiloxane, PDMS) has also been favored by researchers as a low surface energy substance. Because it is an oily viscous liquid at room temperature, it cannot be used directly. It is usually prepared into an emulsion for use. Although polysiloxane is used in food, daily chemicals, pharmaceuticals, etc., it is not biodegradable, and the reaction conditions are harsh in some preparation processes, requiring the use of organic solvents, etc., which are not conducive to industrial production.

In order to minimize the impact of coated paper, fluorine-containing substances and other non-degradable polymers on the environment, degradable polymers represented by PLA are used to replace non-degradable polymers to prepare waterproof and oil-proof paper-based materials. However, PLA Poor thermal stability is not conducive to processing and practical application. In addition, paper materials coated with PLA also face the problem of separation and recycling difficulties. More importantly, PLA is not only expensive, but also difficult to degrade in ordinary environments. Therefore, PLA is not a good choice. Therefore, extensive research has been devoted to improving the water, oil, and gas barrier properties of paper substrates by coating renewable, biocompatible, biodegradable, and nontoxic materials. Natural polymers such as polysaccharides (such as chitosan, cellulose, alginate, starch, etc.), proteins (whey protein, soybean protein, zein, etc.) have been applied to the surface of paper substrates as coatings. Improve the barrier performance and mechanical strength of paper by filling the pores between paper fibers. However, most natural polymers are hydrophilic in nature, their performance is greatly affected by the relative humidity of the environment, and they do not repel water. How to combine natural polymers with hydrophobic substances to prepare waterproof and oil-repellent coatings has almost no industrial applications. The current research is also mostly focused on the method of constructing double coatings. The hydrophobic layer mainly uses PDMS and zein, but its price is much higher than other commonly used sizing agents (AKD, ASA, rosin, etc.). The method and the high coating volume have brought great difficulties to the large-scale application.

Contents of the invention

Based on the above problems, the object of the present invention is to provide a water-based paint with waterproof and oil-repellent properties and its preparation method and application, so as to solve the problem of being unable to provide a good hydrophobic, waterproof, and oil-repellent green and safe paint at the same time. The problem of water and oil repellent coatings that can be applied on a large scale.

In one aspect, the present invention provides a water-based paint with water and oil repellency, comprising the following components:

Hydrophobic ingredients selected from oil-in-water Pickering emulsions;

The anti-oil component is selected from one or more of natural polysaccharides and polyvinyl alcohol.

In the above technical solution, the oil-repellent component can penetrate into the paper to reduce the pores of the paper, and because of its excellent film-forming property, it can form a dense barrier layer to resist oily substances from entering the paper. In addition, natural polysaccharides contain a large number of polar groups that repel the non-polar groups of oil, which further improves the oil-proof performance. In addition, these polar groups can form hydrogen bonds with the hydroxyl groups on the surface of paper fibers. role, thereby improving the mechanical properties of paper.

Further, the natural polysaccharides are selected from one or more of cellulose and its derivatives, chitosan, sodium alginate, starch, and guar gum.

Further, the oil-in-water Pickering emulsion is a hydrophobic material emulsified by nanoparticles.

Further, the nanoparticles are selected from one or more of SiO ₂ , TiO ₂ , ZnO, CaCO ₃ , clay, saponite, nanocellulose, and wood nanocellulose; and/or

The hydrophobic material is selected from one or more of wax, AKD, ASA and rosin.

Further, the wax is selected from one or more of vegetable wax, animal wax, and food-grade paraffin.

Further, in the hydrophobic material emulsified by nanoparticles, the mass ratio of nanoparticles to hydrophobic material to water is 1:80-1:4.

Further, the mass ratio (solid mass ratio) of the hydrophobic component to the oil-repelling component is 60:1-1:2, preferably 30:1-2:1. When the oil-repellent component is too little, it will lead to poor oil repellency; when the hydrophobic component is too little, its waterproof performance will be poor.

In yet another aspect, the present invention provides the preparation method of the water-based paint as described in the first object above, the preparation method may further comprise the steps:

The water-based paint is obtained by mixing a hydrophobic component with an oil-repellent component.

Further, the mixing method is: slowly adding the oil-repellent component into the hydrophobic component under stirring condition.

In yet another aspect, the present invention provides the application of the water-based coating described in the first aspect above in the preparation of hydrophobic and oil-proof paper products.

Further, the water-based coating is applied on the surface of the paper-based material and dried to obtain a hydrophobic and oil-proof paper product.

Further, the applied amount of the water-based paint is above 3g/m ² .

Further, the applying method is one of dip coating, spin coating, blade coating and coating.

Further, the water-based paint can be applied on one surface or both surfaces of the paper-based material, which can be selected according to the actual environment where hydrophobic treatment is required.

Further, the paper base material suitable for the hydrophobic paper of the present invention can be a sheet material with a porous network structure produced from natural plant fibers or substrates. Preferred paper substrates include, but are not limited to, conventionally used papers selected from kraft paper, corrugated paper, parchment paper, newsprint, white cardboard, printing paper, and the like.

Further, the hydrophobic and oil-proof paper products are hydrophobic and oil-proof paper packages, paper straws, paper lunch boxes, paper cups and the like.

The beneficial effects of the present invention are as follows:

In the water-based paint provided by the present invention, the emulsion particles are spherical, have high stability, and avoid the use of organic solvents. After the water-based coating is coated on the paper, the paper has good hydrophobicity, water resistance and oil repellency. Among them, the highest water contact angle can reach more than 130°, the lowest Cobb60 value can reach less than 6g/ ^m2 , the hydrophobic and waterproof performance is greatly improved, the air permeability is greatly reduced, the oil resistance performance is improved, the Kit value is up to 12, and the water vapor transmission rate is greatly improved. Decrease the tensile strength of the paper.

Description of drawings

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Figure 1 shows the SEM image of the water and oil repellent of Example 1.

Fig. 2 shows the macrophotograph diagram of embodiment 1 water and oil repellent.

Fig. 3 shows the state (a) of the water drop on the surface of the waterproof and oil-proof paper in Example 1 and the photo (b) of the water drop on the surface of the paper after 5 minutes of wiping.

Fig. 4 shows the state (a) of embodiment 1 castor oil on the waterproof and oil-proof paper surface and the photo (b) of castor oil after wiping the paper surface 5min.

Detailed ways

In order to illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments and accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not limit the protection scope of the present invention.

Example 1

Take nanocellulose, palm wax, and polyvinyl alcohol as examples:

Use nanocellulose as an emulsifier to form a dispersion with a concentration of 0.3wt%, ultrasonically in a water bath, take a certain amount of nanocellulose aqueous dispersion and add it to a high-speed mixer that integrates heating and stirring, and continue to disperse at 3000rpm for 5 minutes . Then weigh a certain amount of palm wax and add it to the above-mentioned nanocellulose dispersion, so that the ratio of the amount of palm wax to nanocellulose is 30:1, heat to 90° C., and emulsify at 30,000 rpm for 5 minutes. After the emulsification is completed, cool down, and when the temperature of the emulsion drops to room temperature, a milky white O/W Pickering emulsion is obtained, which is put into a container bottle for use.

A 3 wt % polyvinyl alcohol solution was prepared by dissolving 3 g of polyvinyl alcohol in 97 g of water. Take a certain amount of polyvinyl alcohol solution and add it to the stable O/W Pickering emulsion prepared above, and stir it magnetically at 800 rpm for 15 minutes to ensure uniform mixing, and then transfer it to a container bottle for use. Wherein, the mass ratio of polyvinyl alcohol (solid content) to hydrophobic component is 1:60, and a waterproof and oil-repellent coating can be obtained.

Preparation of waterproof and oil-proof paper:

Dry the unsized kraft paper in an oven at 60°C for 5 hours, then apply the water and oil repellent agent on the surface of the paper by coating (only one side coating), the coating amount is 5g/m ² , and The coated paper can be dried in an oven at 70°C for 2 hours. Then its water and oil repellency was characterized. The obtained paper had a water contact angle of 122°, a cobb60 value of 9 g/m ² , a kit value of 8, an air permeability of 0.17 μm/Pa·s, and a tensile strength of 37 MPa. The water contact angle of the blank kraft paper is 60°, the cobb60 value is 88g/m ² , the kit value is 0, and the air permeability is 9.67μm/Pa·s. The tensile strength is 28MPa.

According to ISO535-2014 test the water absorption Cobb60 value of the paper sample. Use a Cobb water absorption tester (ZB-Cobb25) to contact the paper sample with 100mL deionized water at 20±1°C for 60 seconds, and test each sample three times to get the average value.

The grease resistance of the paper samples was tested according to the TAPPI T 559cm-12 standard. Drop solutions 1 to 12 of different ratios of castor oil/heptane/toluene from 2.54cm above the sample, and wipe it after 15 seconds to see if the contact between the sample and the oil drop becomes darker. It is represented by the kit value, where the larger the kit value, the better the oil resistance.

The air permeability of the paper sample is tested according to the ISO5636-2 standard, using the Schhopper method (ZB-TQ1000) to test a sample of 10.0±0.2cm ² in an environment of 20±5°C. At least three different locations were tested for each sample and the average value was taken.

The hydrophobic properties of the samples were characterized by the water contact angle. The water contact angle of the paper samples was measured by a contact angle tester DataPhysics OCA-20 using 3 μL of deionized water at room temperature.

Example 2

Take SiO ₂ , ASA and starch as examples:

Use _SiO2 as an emulsifier to prepare a dispersion with a concentration of 1wt%, ultrasonicate in a water bath, take a certain amount of _SiO2 aqueous dispersion and add it to a high-speed mixer integrating heating and stirring, and continue to disperse at 6000rpm for 3min. Then weigh a certain amount of ASA and add it to the above-mentioned SiO ₂ dispersion, so that the mass ratio of the amount of ASA to SiO ₂ is 4:1, and emulsify at 9000rpm for 4min. After the emulsification is completed, a milky white O/W Pickering emulsion is obtained, which is put into a container bottle for use.

Disperse 2 g of starch in 98 g of water, heat to 95° C. for 1 h, and cool down to prepare a 2 wt % starch solution. Add a certain amount of starch solution to the O/W Pickering emulsion prepared above, and magnetically stir at 500 rpm for 15 minutes to ensure uniform mixing, and then transfer to a container bottle for use. The amount of starch (solid content) and the mass ratio of the hydrophobic component is 1:50, and the waterproof and oil-proof coating can be obtained.

Preparation of waterproof and oil-proof paper:

Dry the unsized white cardboard in an oven at 60°C for 5 hours, then apply the waterproof and oil-repellent agent on the surface of the paper by blade coating (only one side coating), the coating amount is 3g/m ² , And dry the coated paper in an oven at 70°C for 2 hours. Then its water and oil repellency was characterized. The obtained paper had a water contact angle of 125°, a cobb60 value of 7.8 g/m ² , a kit value of 6, an air permeability of 0.23 μm/Pa·s, and a tensile strength of 57 MPa. The water contact angle of the blank white cardboard is 65°, the cobb60 value is 64g/m ² , the kit value is 0, and the air permeability is 7.84μm/Pa·s. The tensile strength is 48MPa.

Example 3

Take TiO ₂ , AKD and chitosan as examples:

Use _TiO2 as an emulsifier to prepare a dispersion with a concentration of 0.3wt%, ultrasonicate in a water bath, take a certain amount of _TiO2 aqueous dispersion and add it to a high-speed mixer integrating heating and stirring, and continue to disperse at 4000rpm for 2min. Then a certain amount of AKD was weighed and added to the above TiO ₂ dispersion so that the mass ratio of AKD to TiO ₂ was 40:1, heated to 80°C, and emulsified at 18000rpm for 2min. After the emulsification is completed, cool down, and when the temperature of the emulsion drops to room temperature, a milky white O/W Pickering emulsion is obtained, which is put into a container bottle for use.

2g chitosan is dispersed in 98g 2% (v/v) acetic acid aqueous solution, stirs 6h, prepares the chitosan solution of 2wt%. Take a certain amount of chitosan solution and add it to the O/W Pickering emulsion prepared above, and stir it magnetically for 15 minutes at 700rpm to ensure uniform mixing, and then transfer it to a container bottle for use. Wherein the mass ratio of the amount of chitosan (solid content) to the hydrophobic component is 1:35, and the waterproof and oil-proof coating can be obtained.

Preparation of waterproof and oil-proof paper:

Dry the unsized corrugated paper in an oven at 60°C for 5 hours, then apply the water and oil repellent on the surface of the paper by spin coating (double-sided coating), the total coating amount is 11g/m ² , and The coated paper can be dried in an oven at 70°C for 2 hours. Then its water and oil repellency was characterized. The obtained paper had a water contact angle of 135°, a cobb60 value of 6.1 g/m ² , a kit value of 7, an air permeability of 0.19 μm/Pa·s, and a tensile strength of 45 MPa. The water contact angle of the blank corrugated paper is 52°, the cobb60 value is 91g/m ² , the kit value is 0, and the air permeability is 9.44μm/Pa·s. The tensile strength is 36MPa.

Example 4

Take clay, rosin and sodium alginate as examples:

Use clay as an emulsifier to prepare a dispersion with a concentration of 0.2wt%, ultrasonicate in a water bath, take a certain amount of clay water dispersion and add it to a high-speed mixer integrating heating and stirring, and continue to disperse at 7000rpm for 5 minutes. Then a certain amount of rosin was weighed and added to the above clay dispersion so that the mass ratio of the amount of rosin to clay was 25:1, heated to 100°C, and emulsified at 20000rpm for 3min. After the emulsification is completed, cool down, and when the temperature of the emulsion drops to room temperature, a milky white O/W Pickering emulsion is obtained, which is put into a container bottle for use.

Disperse 4 g of sodium alginate in 96 g of deionized water and stir for 4 h to prepare a 4 wt % sodium alginate solution. Add a certain amount of sodium alginate solution to the O/W Pickering emulsion prepared above, and magnetically stir at 800 rpm for 15 minutes to ensure uniform mixing, and then transfer to a container bottle for use. Wherein the amount of sodium alginate (solid content) and the mass ratio of the hydrophobic component is 1:60, and the waterproof and oil-proof coating can be obtained.

Preparation of waterproof and oil-proof paper:

Dry the unsized printing paper in an oven at 60°C for 5 hours, then apply the water and oil repellent agent on the surface of the paper by coating (one-side coating), the coating amount is 5g/m ² , and The coated paper can be dried in an oven at 70°C for 2 hours. Then its water and oil repellency was characterized. The obtained paper has a water contact angle of 119°, a cobb60 value of 7.4 g/m ² , a kit value of 5, an air permeability of 0.21 μm/Pa·s, and a tensile strength of 31 MPa. The water contact angle of the blank printing paper is 63°, the cobb60 value is 69g/m ² , the kit value is 0, and the air permeability is 7.49μm/Pa·s. The tensile strength is 23MPa.

Example 5

Take ZnO, beeswax and carboxymethyl cellulose as examples:

Use ZnO as an emulsifier to prepare a dispersion with a concentration of 1wt%, ultrasonicate in a water bath, take a certain amount of ZnO aqueous dispersion and add it to a high-speed mixer integrating heating and stirring, and continue to disperse at 5000rpm for 2min. Then a certain amount of beeswax was weighed and added to the above ZnO dispersion so that the mass ratio of the amount of beeswax to ZnO was 80:1, heated to 80° C., and emulsified at 25,000 rpm for 2 minutes. After the emulsification is completed, cool down, and when the temperature of the emulsion drops to room temperature, a milky white O/W Pickering emulsion is obtained, which is put into a container bottle for use.

Disperse 2 g of carboxymethyl cellulose in 98 g of deionized water and stir for 3 h to prepare a 2 wt % carboxymethyl cellulose solution. Take a certain amount of carboxymethyl cellulose solution and add it to the O/W Pickering emulsion prepared above, and magnetically stir at 700 rpm for 15 minutes to ensure uniform mixing, and then transfer it to a container bottle for use. Wherein the amount of carboxymethyl cellulose (solid content) and the mass ratio of hydrophobic components is 1:20, and the waterproof and oil-proof coating can be obtained.

Preparation of waterproof and oil-proof paper:

The unsized parchment paper was dried in an oven at 60°C for 5 hours, and then the water and oil repellent was coated on the surface of the paper by spin coating (double-sided coating), the total coating amount was 15g/m ² , and Dry the coated paper in an oven at 70°C for 2 hours. Then its water and oil repellency was characterized. The obtained paper had a water contact angle of 133°, a cobb60 value of 5.5 g/m ² , a kit value of 12, an air permeability of 0.08 μm/Pa·s, and a tensile strength of 51 MPa. The water contact angle of blank parchment paper is 41°, the cobb60 value is 85g/m ² , the kit value is 0, and the air permeability is 8.42μm/Pa·s. The tensile strength is 42MPa.

Example 6

Take CaCO ₃ , food grade paraffin and hydroxypropyl cellulose as examples:

Use CaCO ₃ as an emulsifier to prepare a dispersion with a concentration of 0.4wt%, ultrasonicate in a water bath, take a certain amount of CaCO ₃ aqueous dispersion and add it to a high-speed mixer integrating heating and stirring, and continue to disperse at 5500rpm for 3 minutes. Then a certain amount of food-grade paraffin was weighed and added to the above-mentioned CaCO ₃ dispersion, so that the mass ratio of the amount of food-grade paraffin to CaCO ₃ was 15:1, heated to 70°C, and emulsified at 20,000 rpm for 5 min. After the emulsification is completed, cool down, and when the temperature of the emulsion drops to room temperature, a milky white O/W Pickering emulsion is obtained, which is put into a container bottle for use.

Disperse 2 g of hydroxypropyl cellulose in 98 g of deionized water and stir for 3 h to prepare a 2 wt % hydroxypropyl cellulose solution. Take a certain amount of hydroxypropyl cellulose solution and add it to the O/W Pickering emulsion prepared above, and stir it magnetically at 800 rpm for 15 minutes to ensure uniform mixing, and then transfer it to a container bottle for use. The mass ratio of the amount of hydroxypropyl cellulose (solid content) to the hydrophobic component is 1:0.5, and the waterproof and oil-proof coating can be obtained.

Preparation of waterproof and oil-proof paper:

Dry the unsized newsprint in an oven at 60°C for 5 hours, then apply the waterproof and oil-repellent agent on the surface of the paper by blade coating (double-sided coating), the total coating amount is 8g/m ² , and The coated paper can be dried in an oven at 70°C for 2 hours. Then its water and oil repellency was characterized. The obtained paper had a water contact angle of 119°, a cobb60 value of 8.9 g/m ² , a kit value of 6, an air permeability of 0.18 μm/Pa·s, and a tensile strength of 16 MPa. The water contact angle of newsprint is 26°, the cobb60 value is 90g/m ² , the kit value is 0, and the air permeability is 12.4μm/Pa·s. The tensile strength is 9.8MPa.

Example 7

Take lignocellulose, palm wax and polyvinyl alcohol as examples:

Use lignonanocellulose as an emulsifier to form a dispersion with a concentration of 0.05wt%, ultrasonicate in a water bath, take a certain amount of lignonanocellulose aqueous dispersion and add it to a high-speed mixer integrating heating and stirring, and continue at 6000rpm Disperse for 3min. Then a certain amount of palm wax was weighed and added to the above-mentioned lignocellulose dispersion, so that the mass ratio of the amount of palm wax to lignocellulose was 45:1, heated to 90° C., and emulsified at 30,000 rpm for 5 minutes. After the emulsification is completed, cool down, and when the temperature of the emulsion drops to room temperature, a milky white O/W Pickering emulsion is obtained, which is put into a container bottle for use.

A 3 wt % polyvinyl alcohol solution was prepared by dissolving 3 g of polyvinyl alcohol in 97 g of water. Take a certain amount of polyvinyl alcohol solution and add it to the stable O/W Pickering emulsion prepared above, and stir it magnetically at 800 rpm for 15 minutes to ensure uniform mixing, and then transfer it to a container bottle for use. Wherein the amount of polyvinyl alcohol (solid content) and the mass ratio of the hydrophobic component is 1:0.5, and the waterproof and oil-proof coating can be obtained.

Preparation of waterproof and oil-proof paper:

Dry the unsized kraft paper in an oven at 60°C for 5 hours, then apply the water and oil repellent on the surface of the paper by coating (only one side coating), the coating amount is 7g/m ² , and The coated paper can be dried in an oven at 70°C for 2 hours. Then its water and oil repellency was characterized. The obtained paper had a water contact angle of 120°, a cobb60 value of 9.4 g/m ² , a kit value of 11, an air permeability of 0.11 μm/Pa·s, and a tensile strength of 41 MPa. The water contact angle of the blank kraft paper is 60°, the cobb60 value is 88g/m ² , the kit value is 0, and the air permeability is 9.67μm/Pa·s. The tensile strength is 28MPa.

Example 8

Take saponite, ASA and sodium alginate as examples:

Use saponite as an emulsifier to prepare a dispersion with a concentration of 0.5wt%, ultrasonically in a water bath, take a certain amount of saponite water dispersion and add it to a high-speed mixer that integrates heating and stirring, and continue to disperse at 5500rpm for 3 minutes . Then a certain amount of ASA was weighed and added to the above saponite dispersion, so that the mass ratio of the amount of ASA to saponite was 35:1, heated to 90°C, and emulsified at 30000rpm for 5min. After the emulsification is completed, cool down, and when the temperature of the emulsion drops to room temperature, a milky white O/W Pickering emulsion is obtained, which is put into a container bottle for use.

Disperse 2 g of sodium alginate in 98 g of deionized water and stir for 3 h to prepare a 2 wt % sodium alginate solution. Add a certain amount of sodium alginate solution to the O/W Pickering emulsion prepared above, and magnetically stir at 800 rpm for 15 minutes to ensure uniform mixing, and then transfer to a container bottle for use. Wherein the mass ratio of the amount of sodium alginate (solid content) to the hydrophobic component is 1:10, and the waterproof and oil-proof coating can be obtained.

Preparation of waterproof and oil-proof paper:

Dry the unsized kraft paper in an oven at 60°C for 5 hours, then apply the water and oil repellent on the surface of the paper by coating (only one side coating), the coating amount is 4g/m ² , and The coated paper can be dried in an oven at 70°C for 2 hours. Then its water and oil repellency was characterized. The obtained paper had a water contact angle of 122°, a cobb60 value of 8.3 g/m ² , a kit value of 4, an air permeability of 0.27 μm/Pa·s, and a tensile strength of 37 MPa. The water contact angle of the blank kraft paper is 60°, the cobb60 value is 88g/m ² , the kit value is 0, and the air permeability is 9.67μm/Pa·s. The tensile strength is 28MPa.

Example 9

Use lignonanocellulose as an emulsifier to form a dispersion with a concentration of 0.1wt%, ultrasonicate in a water bath, take a certain amount of lignonanocellulose aqueous dispersion and add it to a high-speed mixer that integrates heating and stirring, and continue at 8000rpm Disperse for 3min. Then a certain amount of palm wax was weighed and added to the above-mentioned lignocellulose dispersion, so that the mass ratio of the amount of palm wax to lignocellulose was 60:1, heated to 90° C., and emulsified at 30,000 rpm for 4 minutes. After the emulsification is completed, cool down, and when the temperature of the emulsion drops to room temperature, a milky white O/W Pickering emulsion is obtained, which is put into a container bottle for use.

A 2 wt % guar solution was prepared by dissolving 2 g of guar gum in 98 g of water. Take a certain amount of guar gum solution and add it to the stable O/W Pickering emulsion prepared above, and stir it magnetically for 15 minutes at 800 rpm to ensure uniform mixing, and then transfer it to a container bottle for use. Wherein the mass ratio of the amount of guar gum (solid content) to the hydrophobic component is 1:19, and the waterproof and oil-proof coating can be obtained.

Preparation of waterproof and oil-proof paper:

Dry the unsized kraft paper in an oven at 60°C for 5 hours, then apply the water and oil repellent on the surface of the paper by coating (only one side coating), the coating amount is 10g/m ² , and The coated paper can be dried in an oven at 70°C for 2 hours. Then its water and oil repellency was characterized. The obtained paper had a water contact angle of 123°, a cobb60 value of 8.8 g/m ² , a kit value of 12, an air permeability of 0.03 μm/Pa·s, and a tensile strength of 43 MPa. The water contact angle of the blank kraft paper is 60°, the cobb60 value is 88g/m ² , the kit value is 0, and the air permeability is 9.67μm/Pa·s. The tensile strength is 28MPa.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those of ordinary skill in the art can also make It is not possible to exhaustively list all the embodiments here, and any obvious changes or changes derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims (10)

A kind of water-based paint with waterproof and oil-proof performance, is characterized in that, comprises following component: Hydrophobic ingredients selected from oil-in-water Pickering emulsions; The anti-oil component is selected from one or more of natural polysaccharides and polyvinyl alcohol. The water-based coating according to claim 1, wherein the natural polysaccharide is selected from one or more of cellulose and its derivatives, chitosan, sodium alginate, and starch. The water-based coating according to claim 1, wherein the oil-in-water Pickering emulsion is a hydrophobic material emulsified by nanoparticles. The water-based coating according to claim 3, wherein the nanoparticles are selected from one of SiO ₂ , TiO ₂ , ZnO, CaCO ₃ , clay, saponite, nanocellulose, wood nanocellulose or several; and/or The hydrophobic material is selected from one or more of wax, AKD, ASA and rosin. The water-based coating according to claim 3 or 4, characterized in that, in the hydrophobic material emulsified by nanoparticles, the mass ratio of nanoparticles to hydrophobic material to water is 1:80-1:4. The water-based paint according to claim 1, wherein the mass ratio of the hydrophobic component to the oil-repellent component is 30:1-2:1. The preparation method of the water-based coating as described in any one of claims 1-6, is characterized in that, comprises the steps: The water-based paint is obtained by mixing a hydrophobic component with an oil-repellent component. Application of the water-based coating as described in any one of claims 1-6 in the preparation of hydrophobic and oil-proof paper products. The application according to claim 8, characterized in that, the water-based paint is applied on the surface of the paper-based material and dried to obtain a hydrophobic and oil-proof paper product. The application according to claim 9, characterized in that the application method is one of dip coating, spin coating, blade coating and coating.

Images