Washable hydrophobic oil-proof color-fixing type dyed paper and manufacturing method thereof

Abstract

The invention provides washable hydrophobic oil-proof color-fixing type dyed paper and a manufacturing method thereof, and the method comprises the following steps: with dip-dyed raw paper as a matrix raw material, sequentially carrying out dip dyeing, pre-drying, surface sizing and post-drying to obtain a washable hydrophobic oil-proof color-fixing type dyed paper material; the dip dyeing is carried out by adopting a hydrophobic dyeing coating, the hydrophobic dyeing coating comprises a dye, a water-based food-grade hydrophobic fixation auxiliary agent and water, and the water-based food-grade hydrophobic fixation auxiliary agent comprises nano-scale acrylic resin, food-grade fluoride-free trialkoxysilane and hydrophilic nano silicon dioxide. The preparation method has the advantages of green and environment-friendly preparation process, simple process, good color fixation and the like, and has higher application value in the fields of plastic-replacing dyeing art paper, paper-based dining table cloth and the like.

Description

Technical Field

[0001] The present invention belongs to the technical fields of functional coatings and papermaking, and particularly relates to a water-washable hydrophobic and oil-proof color-fixing dyed paper and a manufacturing method thereof. Background Art

[0002] With the increasing dual demands of consumers for the aesthetics and functionality of product packaging, dyed papers have received more and more attention in the market due to their unique colors and decorative effects. Especially in the packaging fields of high-value-added products such as food, cosmetics, and electronic products, the demand for dyed papers continues to grow.

[0003] Conventional papers are porous two-dimensional film-like materials formed by the interweaving of cellulose fibers with multiple hydroxyl groups on the surface. Therefore, they have natural hydrophilicity and certain lipophilicity (with a relatively high porosity and unable to achieve oil-proof through a barrier effect). Among them, hydrophilicity causes the mechanical properties of dyed papers to drop sharply and break in a water-related environment. At the same time, after the dyed papers absorb water, it will affect the uniform stability of the hue. In daily use, especially in application environments related to food, the oil-proof performance is also one of the key performance indicators that need to be focused on. Therefore, hydrophilicity and lipophilicity largely limit the wide application of plastic-replacing dyed papers. Currently, the processes for preparing dyed papers include various methods, among which internal sizing dyeing and external sizing dyeing are two common techniques. Internal sizing dyeing is to directly add dyes to the pulp during the papermaking process for dyeing. The advantage of this method is that the combination of the dye and cellulose fibers is relatively tight, which can improve the color adhesion rate and color fastness. However, internal sizing dyeing also has some disadvantages. For example, it may affect the strength and whiteness of the paper. External sizing dyeing is to apply dyes to the surface of the paper by means of impregnation, coating, or spraying after the paper is formed. This method is simple to operate, but the color adhesion rate is low, it is easy to fade when encountering water, and it may cause secondary pollution.

[0004] Currently, the main process for preparing oil-proof papers is the surface coating method. Usually, natural polymer materials such as chitosan and nanofibrillated cellulose are used as oil-proof agents, and an oil-proof layer is formed by coating them on the base paper. To endow materials with hydrophobicity, it is usually necessary to introduce oily compounds with a low surface energy and utilize the "immiscibility of oil and water" to achieve water resistance / hydrophobic performance. However, due to the similarity of the structures and physicochemical properties of oily compounds, they are extremely soluble in oil. Therefore, it is a major scientific challenge to simultaneously achieve the hydrophobic and oil-proof properties of materials without introducing fluorine-containing compounds with an extremely low surface energy.

[0005] In order to meet the quality requirements and stable appearance hues of dyed paper-based materials used in different occasions, how to endow dyed paper-based materials with stable hydrophobicity, oil-proofness, and color-fixing characteristics through an economical and environmentally friendly process has important scientific significance and practical value in expanding the application of dyed papers in the field of paper-based plastic replacement. Summary of the Invention

[0006] Based on the key common technical problems to be solved urgently described in the above research background, the purpose of the present invention is to provide a water-washable, oil-proof, and fixed-color type dyeing paper with both waterproof (hydrophobic) and oil-proof properties, and its manufacturing method, which has the advantages of being green and environmentally friendly in the preparation process, simple process, and good color fixation, and has high application value in many fields such as replacing plastic dyeing art paper and paper-based tablecloths.

[0007] The present invention provides a manufacturing method of a water-washable, hydrophobic and oil-proof fixed-color type dyeing paper, comprising the following steps:

[0008] Using the impregnated base paper as the matrix raw material, successively carrying out impregnation, pre-drying, surface sizing, and post-drying to obtain a water-washable, hydrophobic and oil-proof fixed-color type dyeing paper material;

[0009] The impregnation is carried out using a hydrophobic dyeing coating, and the hydrophobic dyeing coating contains a dye, a water-based food-grade hydrophobic color-fixing aid, and water. The water-based food-grade hydrophobic color-fixing aid contains: nano-scale acrylic resin, food-grade fluorine-free trialkoxysilane, and hydrophilic nano-silica; the mass ratio of the dye, the water-based food-grade hydrophobic color-fixing aid to water is 1:(1-2):(7-8);

[0010] The surface sizing is carried out using a water-based fluorine-free oil-proof functional coating, and the water-based fluorine-free oil-proof functional coating contains starch, acrylate copolymer, and dodecyl sulfate; the water-based fluorine-free oil-proof functional coating is neutral.

[0011] In an embodiment of the present invention, in the hydrophobic dyeing coating, the dye is a liquid color paste or a solid dye aqueous dispersion.

[0012] In an embodiment of the present invention, in the water-based food-grade hydrophobic color-fixing aid, the solid content of the nano-scale acrylic resin is 35-40%, and the particle size is 40-70 nm.

[0013] In an embodiment of the present invention, the preparation of the water-based fluorine-free oil-proof functional coating includes:

[0014] Mixing starch, dodecyl sulfate, and an initiator, adding water and heating to obtain a dispersion;

[0015] Mixing methyl methacrylate, butyl acrylate, and methacrylic acid, adding them to the dispersion, heating and reacting, and adjusting the pH value to neutral to obtain the water-based fluorine-free oil-proof functional coating.

[0016] In the embodiments of the present invention, in the preparation of the aqueous fluorine-free oil-proof functional coating, the mass ratio of the starch, dodecyl sulfate and initiator is (3-5):(5-6):1; the mass ratio of methyl methacrylate, butyl acrylate and methacrylic acid is (10-12):(10-14):(0.8-1).

[0017] In the embodiments of the present invention, in the preparation of the aqueous fluorine-free oil-proof functional coating, the initiator is persulfate; the temperature of the heating reaction is 60-100 °C, the time is 1-3 h, and the pH value is adjusted to 6.8-7.2 with ammonia water.

[0018] In the embodiments of the present invention, the basis weight of the impregnated base paper is 80-120 g / m 2 , and the water absorption value is 100-250 g / m 2 .

[0019] In the embodiments of the present invention, after impregnation, it is dried in an oven and then enters pre-drying; the temperatures of the oven drying and pre-drying are 80-150 °C respectively.

[0020] The present invention provides a hydrophobic oil-proof color-fixing type dyed paper material obtained by the manufacturing method as described above, and its water absorption value is 2.5 g / m 2 or less.

[0021] In the embodiments of the present invention, the water absorption value of the hydrophobic oil-proof color-fixing type dyed paper material is 1.0-2.3 g / m 2 .

[0022] Compared with the prior art, the present invention uses impregnated base paper as raw material, and through the main processes of "specific hydrophobic dyeing coating impregnation - pre-drying - specific aqueous fluorine-free oil-proof functional coating surface sizing - post-drying", finally obtains a water-washable hydrophobic oil-proof color-fixing type dyed paper material. The present invention uses two different impregnation and coating processes on the same production line to centrally realize the dyeing, waterproofing (hydrophobic) and oil-proofing treatments of paper-based materials, and overcomes the scientific problem that the waterproofing (hydrophobic) coating is lipophilic due to its low surface energy under conventional conditions without fluorine, and successfully develops a fluorine-free waterproof and oil-proof dyed paper. Among them, the color-fixing aid contains nano-level acrylic resin, and through its unique chemical structure and physical properties, it can effectively improve the dispersibility and adhesion of dyes, thereby improving the color-fixing effect; at the same time, the addition of hydrophilic silica inorganic nanoparticles has a significant impact on the color stability of the nano-level acrylic resin. The dyed paper produced in the embodiments of the present invention has no color fading phenomenon (at least 3 days) after being soaked in water environment for a long time, and the Cobb value can be as low as 1.0 g / m 2 , the water contact angle is as high as 130°, and the oil-proof grade can reach 8 levels, having excellent waterproof and oil-proof characteristics.

[0023] In addition, the coating materials used are all food-grade materials, making the waterproof, oil-proof and color-fixing dyed paper produced by the present invention have broad application prospects in the field of plastic substitution. Description of the Drawings

[0024] Figure 1 It is a photo of the dyed paper produced in Example 1 after being folded 1000 times (the coating has no obvious cracks);

[0025] Figure 2 It is a comparison photo of the oil-proof performance between the oil-proof dyed paper and the dyed paper in Example 2;

[0026] Figure 3 It is a scanning electron microscope comparison photo of the oil-proof paper and the original paper in Comparative Example 2. Detailed Description of the Invention

[0027] In order to more clearly understand the technical features, objectives and effects of the present invention, the technical solutions of the present invention will be described in detail below with reference to specific embodiments. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0028] The present invention provides a method for manufacturing a water-washable hydrophobic, oil-proof and color-fixing dyed paper, which includes the following steps:

[0029] Using the impregnated base paper as the matrix raw material, successively carrying out impregnation, pre-drying, surface sizing and post-drying to obtain a water-washable hydrophobic, oil-proof and color-fixing dyed paper material;

[0030] The impregnation is carried out with a hydrophobic dyeing coating, and the hydrophobic dyeing coating contains a dye, a water-based food-grade hydrophobic color-fixing aid and water. The water-based food-grade hydrophobic color-fixing aid contains: nano-scale acrylic resin, food-grade fluorine-free trialkoxysilane and hydrophilic nano-silica; the mass ratio of the dye, the water-based food-grade hydrophobic color-fixing aid to water is 1:(1-2):(7-8);

[0031] The surface sizing is carried out with a water-based fluorine-free oil-proof functional coating, and the water-based fluorine-free oil-proof functional coating contains starch, acrylate copolymer and dodecyl sulfate; the water-based fluorine-free oil-proof functional coating is neutral.

[0032] The method for manufacturing the dyed paper-based material of the present invention has the characteristics of simple process, economy and environmental protection. The obtained dyed paper material has good color fixation, stable hydrophobicity and oil-proofness, and is conducive to application.

[0033] First, the steps of the embodiment of the present invention are the compounding of a solid dye dispersion / liquid color paste and a hydrophobic color-fixing agent to obtain a hydrophobic dyeing coating with hydrophobic and color-fixing effects. Specifically, a black / yellow color paste or a dye dispersion with a certain mass fraction can be mixed with an aqueous food-grade hydrophobic color-fixing agent and water in a mass ratio of 1:(1-2):(7-8), and a high-speed disperser can be used to stir evenly to obtain a functional coating.

[0034] Based on the above technical solutions, preferably, the dye materials include two categories: liquid color paste and solid dye aqueous dispersion. Among them, the mass fraction of the yellow / black color paste is 30-45%, and its mass fraction can be flexibly adjusted according to the specific requirements of color depth. In the current process, it is preferably 38-40%; the mass fraction of the solid dye aqueous dispersion is 10-40%. In order to make the final dyed paper have an ideal coloring effect, in the current process, it is preferably 20-30%.

[0035] The dye is an organic compound that can dissolve in water, oil or other solvents, and can penetrate into the fiber interior and react with the fiber to achieve coloring. The dyes involved in some embodiments of the present invention are solids and are formulated into dye aqueous dispersions with water. The color paste is a semi-finished product made by mixing pigments or pigments and fillers through processes such as grinding and dispersion; in some embodiments of the present invention, the color paste is a yellow / black liquid, and the mass fraction of the color paste pigment is 30-45%.

[0036] Based on the above technical solutions, preferably, the aqueous food-grade hydrophobic color-fixing agent is composed of a nano-scale acrylic resin, a food-grade fluorine-free trialkoxysilane, and a hydrophilic nano-silica dispersion in a specific ratio. The acrylic resin is the general term for substituted or unsubstituted acrylic acid and its derivatives, including production methods such as emulsion polymerization, suspension polymerization, and bulk polymerization; it is divided into thermosetting and thermoplastic acrylic resins in terms of structure and performance. The embodiment of the present invention uses an aqueous acrylic resin material, in which the polymer has a nano-particle morphology; the solid content of the nano-scale acrylic resin is preferably 35-40%, more preferably 38%; the particle size is preferably 40-70 nm, more preferably 50 nm; the room temperature viscosity can be 12-25 cp, preferably 20 cp.

[0037] Among them, the food-grade fluorine-free trialkoxysilane is a food-grade low surface energy silane-based modifier without fluorine; it is preferably one of methyltrimethoxysilane and 3-aminopropyltriethoxysilane. Moreover, in the embodiments of the present invention, a hydrophilic nano-silica dispersion is further added to further improve color stability. The mass fraction of the hydrophilic nano-silica dispersion is preferably 1-4%, more preferably 1-3%, and most preferably 2%. Specifically, nano-acrylic resin: food-grade fluorine-free low surface energy modifier: hydrophilic nano-silica dispersion = 2:1:100 (mass ratio).

[0038] Based on the above technical solutions, the stirring speed during the preparation of the aqueous food-grade hydrophobic color fixing agent can be 1000-2500 rpm, more preferably 1500-2500 rpm, and most preferably 2000 rpm; the stirring time is preferably 20-60 min, more preferably 20-40 min, and most preferably 30 min. In addition, the aqueous food-grade hydrophobic color fixing agent can use the commercially available GS-03 product, and its basic structure is a nano-acrylate resin (solid content 38%, provided by Shanghai Xianke Chemical Co., Ltd.).

[0039] Meanwhile, the embodiments of the present invention can carry out the preparation steps of an aqueous fluorine-free oil-proof functional coating. Specifically, tapioca starch, sodium dodecyl sulfate, and ammonium persulfate can be mixed, and then a certain amount of water (which can be deionized water) is added for sufficient stirring and heating to obtain a dispersion; then the monomer mixture of methyl methacrylate, butyl acrylate, and methacrylic acid is slowly added dropwise to the dispersion, and heating is continued for a period of time for reaction. After the reaction is completed, it is cooled to room temperature, and it can be filtered through a 200-mesh sieve. It is preferably to adjust the pH value to 6.8-7.2 with ammonia water, and more preferably adjusted to 7 to obtain an aqueous fluorine-free oil-proof functional coating.

[0040] Based on the above technical solutions, when preparing the dispersion with tapioca starch, sodium dodecyl sulfate, ammonium persulfate, and water, the starch can be of other types. The dodecyl sulfate is specifically the sodium salt, and the initiator is a persulfate, preferably ammonium persulfate. The preferred mass ratio is (3-5):(5-6):1:120, further 4:6:1:120; the heating temperature can be 60-100 °C, more preferably 80 °C, the stirring speed is 200-400 rpm, more preferably 300 rpm, and the stirring time is 10-40 min, more preferably 30 min.

[0041] Afterwards, when using the monomer mixture of methyl methacrylate, butyl acrylate and methacrylic acid, preferably, the mass ratio of methyl methacrylate, butyl acrylate and methacrylic acid is (10-12):(10-14):(0.8-1), more preferably 12:12:1. When preparing the oil-proof functional coating with the above-mentioned dispersion liquid, the stirring speed is preferably 500-1000 rpm, more preferably 600-800 rpm, the reaction temperature is 60-100 °C, further 70-90 °C, and the reaction time is 1-3 h, specifically 2 h.

[0042] In the embodiments of the present invention, it mainly overcomes the problem that the surface of hydrophobic materials usually shows a certain degree of lipophilicity. Without using materials with ultra-low surface energy such as fluorocarbons, it is very difficult to simultaneously achieve the hydrophobic and oleophobic properties of materials in the same aqueous system. This is because hydrophobic materials achieve superhydrophobicity by reducing the surface energy and increasing the surface roughness, so that water droplets form a large contact angle on the surface and are easy to slide off, achieving a self-cleaning effect. However, these materials show extremely high affinity for oil-based liquids because oil-based liquids are non-polar and have a small interaction force with the hydrophobic surface, resulting in the rapid spreading and adsorption of oil droplets on the hydrophobic surface.

[0043] The embodiments of the present invention use impregnated base paper with a relatively high water absorption value as the raw material, and combine the process of "impregnation (the hydrophobic dyeing coating) - oven - pre-drying cylinder - surface sizing machine (the oil-proof functional coating) - post-drying cylinder - calendering - coiling" to achieve hydrophobic dyeing and oil-proof treatment on the same production line. The method of the present invention is flexible in operation, overcomes the contradiction that hydrophobic and oleophobic properties are difficult to be compatible in an aqueous system without fluorine, and successfully prepares a fluorine-free food-grade hydrophobic, oleophobic, fold-resistant and water-resistant dyed paper.

[0044] Based on the above technical solutions, in the above steps, the quantitative range of the impregnated base paper with a relatively high water absorption value is generally 80-120 g / m 2 , more preferably 80 g / m 2 ; the water absorption value (Cobb value) range is 100-250 g / m 2 , more preferably 120 g / m 2 .

[0045] When impregnating with the hydrophobic dyeing coating, the impregnation sizing speed can be 50 - 200 m / min, and the impregnation time is about 3 - 8 s to form the colored paper material. For the impregnation process, it is recommended to control the temperature at 40 - 60 °C and the impregnation time at 3 - 8 s to ensure uniform coloring of the fibers. The drying of the impregnated and coated dyed paper consists of two parts: the drying section and the dryer cylinders. The actual drying time is related to the selected paper thickness, Cobb value, and the running speed of the instrument, and can be flexibly adjusted in actual production. For example, the drying temperatures in two stages are 80 - 150 °C respectively. Also, sizing is carried out through an impregnation sizing machine, and the coating amount is 3 - 8 g / m 2 ; The calendering and curling are both conventional operations without special restrictions. The temperature gradient of the oven is preferably controlled in a three - stage manner of 120 - 150 - 100 °C, the wind speed is 8 - 12 m / s, and the residence time is 20 - 40 s; The temperature of the front dryer cylinder group can be 80 - 110 °C, and the line pressure is 20 - 40 kN / m to increase the dryness of the paper to 65 - 75%.

[0046] In addition, the sizing machine should control the glue solution concentration at 5 - 12% and the coating amount at 3 - 8 g / m 2 , and the penetration depth of the sizing material needs to reach more than 1 / 3 of the paper web thickness; The temperature of the rear dryer cylinder decreases in a stepped manner (95 - 80 - 65 °C) to prevent the sizing layer from wrinkling. The line pressure of the calendering process is 50 - 150 kN / m, the roll surface temperature is 60 - 90 °C, and the vehicle speed matches the re - wetting rate of the paper after sizing (±2%); The curling tension is controlled at 0.8 - 1.5 kN / m to ensure the reel tightness of 650 - 850 kg / m 3 . In actual production, parameters need to be adjusted according to the paper type (printing paper / packaging paper). Excessive drying of the front dryer cylinder will affect the sizing effect, and too large a temperature difference in the rear dryer cylinder is likely to cause curling defects, and it is necessary to monitor in real - time through an on - line moisture meter (control accuracy ±0.5%).

[0047] The present invention also relates to a hydrophobic oil - proof color - fixing type dyed paper material obtained according to the manufacturing method described above. It has hydrophobicity, and the water absorption value is 2.5 g / m 2 The following (specifically, it can be 1.0 - 2.3 g / m 2 ), and the water contact angle can be as high as 130°; The oil - proof grade can reach level 8, and it has excellent waterproof and oil - proof properties.

[0048] The dyed paper produced in the embodiments of the present invention does not fade after being soaked in water for a long time, has good color - fixing performance, and is resistant to washing and folding. At the same time, all the coating materials used are food - grade materials, making the color - fixing type dyed paper produced by the present invention have broad application prospects in the field of replacing plastics and other fields.

[0049] To further understand the present invention, the present invention will be described in detail below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments. In the embodiments, all the original reagents and materials are commercially available, and the experimental methods without specific experimental conditions are conventional methods and conditions well-known in the art.

[0050] Example 1

[0051] First, the aqueous food-grade hydrophobic color fixing aid is obtained by mixing 38% of nanoacrylate resin GS-03 (Shanghai Xianke Chemical Co., Ltd.), food-grade fluorine-free low surface energy modifier 3-aminopropyltriethoxysilane and hydrophilic nano-silica dispersion liquid (2%, 50 nm) in a mass ratio of 2:1:100. Then, a black solid dye dispersion liquid with a mass fraction of 30% is mixed with the prepared aqueous food-grade hydrophobic color fixing aid and water in a mass ratio of 1:2:7, and then stirred at 2000 rpm for 30 min to obtain hydrophobic dyeing coating A.

[0052] Next, cassava starch, sodium dodecyl sulfate, ammonium persulfate and water are mixed in a mass ratio of 4:6:1:120, stirred at 80 °C and 300 rpm for 30 min to obtain dispersion liquid B. Then, methyl methacrylate, butyl acrylate and methacrylic acid are mixed in a mass ratio of 12:12:1 to obtain monomer mixture C. C is slowly added dropwise to dispersion liquid B, and then reacted with stirring at the above temperature and 600 rpm for 2 h to obtain oil-proof coating D.

[0053] Finally, with a quantitative amount of 125 g / m 2 , and a Cobb value of 211 g / m 2 The impregnated base paper is processed through the process of "impregnation (hydrophobic dyeing coating A) - oven - pre-drying cylinder - sizing machine (oil-proof coating D) - post-drying cylinder - calendering - coiling" to obtain a water-washable superhydrophobic oil-proof color fixing type dyed paper material.

[0054] Among them, the temperature of the impregnation process is controlled at 50 °C and the impregnation time is 4 - 6 s to ensure uniform coloring of the fibers; the temperature gradient of the oven is preferably controlled in a three-stage manner of 120 - 150 - 100 °C, the wind speed is 8 - 12 m / s, and the residence time is 30 s; the temperature of the pre-drying cylinder group is 105 °C, and the line pressure is 30 kN / m to increase the dryness of the paper to 65 - 75%. The sizing machine should control the glue solution concentration at 5% and the coating amount at 3 - 8 g / m 2 , and the penetration depth of the sizing material needs to reach more than 1 / 3 of the paper thickness; the temperature of the post-drying cylinder decreases step by step (95 - 80 - 65 °C) to prevent the glue layer from wrinkling. The line pressure of the calendering process is 100 kN / m, the roll surface temperature is 80 °C, and the vehicle speed matches the rewetting rate of the paper after sizing (±2%); the coiling tension is controlled at 1.0 - 1.3 kN / m to ensure a reel tightness of 800 kg / m 3In actual production, parameters need to be adjusted according to the paper type (printing paper / packaging paper). Excessive drying of the front drying cylinder will affect the sizing effect, and too large a temperature difference in the rear drying cylinder is likely to cause curling defects. It is necessary to monitor in real time through an on-line moisture meter (control accuracy ±0.5%).

[0055] The obtained dyed paper was soaked in water at room temperature for 7 days, taken out and wiped with blotting paper, and there was no obvious color fading on the surface. As Figure 1 shown, after folding 1000 times, there were no cracks on the surface coating of the dyed paper, and the surface color fixation effect was excellent. At the same time, the Cobb value of the dyed paper was measured to be 2.3 g / m 2 .

[0056] The oil-proof grade of the paper is specified in GB / T 22805.2-2008. The test liquid is dropped on the paper surface from a certain height, wiped off after 15 s, and whether there are dark spots on the paper surface is observed to judge the oil-proof grade. After multiple tests, the oil-proof grade of the paper produced by the present invention can be stably at grade 7.

[0057] Example 2

[0058] First, the water-based food-grade hydrophobic color-fixing aid is obtained by mixing 38% nanoacrylate resin GS-03, food-grade fluorine-free low surface energy modifier methyltrimethoxysilane and hydrophilic nano-silica dispersion liquid (2%, 50 nm) in a mass ratio of 2:1:100. Then, a yellow pulp with a mass fraction of 40% is selected as the dye material, mixed with the prepared water-based food-grade hydrophobic color-fixing aid and water in a mass ratio of 1:2:7, and then stirred at 2000 rpm for 30 min to obtain hydrophobic dyeing coating A.

[0059] Next, tapioca starch, sodium dodecyl sulfate, ammonium persulfate and water are mixed in a mass ratio of 4:6:1:120, stirred at 80 °C and 300 rpm for 30 min to obtain dispersion liquid B. Then, methyl methacrylate, butyl acrylate and methacrylic acid are mixed in a mass ratio of 12:12:1 to obtain monomer mixture C. C is slowly added dropwise to dispersion liquid B, and then reacted with stirring at the above temperature and 600 rpm for 2 h to obtain oil-proof coating D.

[0060] Finally, using a sizing base paper with a basis weight of 80 g / m 2 and a Cobb value of 137 g / m 2 through the process of "dyeing (hydrophobic dyeing coating A) - oven - front drying cylinder - sizing machine (oil-proof coating D) - rear drying cylinder - calendering - curling", a superhydrophobic oil-proof color-fixing type dyed paper material resistant to washing is obtained.

[0061] Among them, in the impregnation process, the temperature is controlled at 50°C and the impregnation time is 4 - 6 s to ensure uniform coloring of the fibers; the temperature gradient of the oven is preferably controlled in a three-stage manner of 120 - 150 - 100°C, the wind speed is 8 - 12 m / s, and the residence time is 30 s; the temperature of the front drying cylinder group is 105°C and the linear pressure is 30 kN / m to increase the dryness of the paper to 65 - 75%. The sizing machine should control the sizing solution concentration at 12% and the coating amount at 3 - 8 g / m 2 , and the penetration depth of the sizing material needs to reach more than 1 / 3 of the paper sheet thickness; the temperature of the rear drying cylinder decreases in a stepwise manner (95 - 80 - 65°C) to prevent the sizing layer from wrinkling. The linear pressure of the calendering process is 150 kN / m, the roll surface temperature is 80°C, and the vehicle speed matches the rewetting rate of the paper sheet after sizing (±2%); the coiling tension is controlled at 1.0 - 1.3 kN / m to ensure the reel tightness of 750 kg / m 3 .

[0062] The obtained dyed paper is soaked in water at room temperature for 7 days, taken out and wiped with absorbent paper, and there is no obvious color fading on the surface. After folding 1000 times, there are no cracks on the surface coating of the dyed paper, and the surface color fixation effect is excellent. At the same time, the Cobb value of the dyed paper is measured to be 1.0 g / m 2 , and the oil-proof grade is 8.

[0063] Comparative Example 1

[0064] For further comparative illustration, in this comparative example, only the paper base material is subjected to hydrophobic-dyeing treatment without oil-proof treatment. First, the water-based food-grade hydrophobic color-fixing aid is prepared by mixing 38% of nano-level acrylate resin GS-03 (its basic structure is nano-level acrylate resin, provided by Shanghai Xianke Chemical Co., Ltd.), food-grade fluorine-free low-surface-energy modifier methyltrimethoxysilane and hydrophilic nano-silica dispersion liquid (2%, 50 nm) in a mass ratio of 2:1:100. Then, a yellow paste with a mass fraction of 40% is selected as the dye material, mixed with the prepared water-based food-grade hydrophobic color-fixing aid and water in a mass ratio of 1:2:7, and then stirred at 2000 rpm for 30 min to obtain hydrophobic dyeing coating A.

[0065] With a basis weight of 80 g / m 2 , and a Cobb value of 137 g / m 2The impregnated base paper is processed through the process of "impregnation (hydrophobic dyeing coating A) - oven - pre - drying cylinder - post - drying cylinder - calendering - coiling" to obtain a super - hydrophobic color - fixing type dyeing paper material with water - washing resistance. The process conditions are simplified from the examples. For the impregnation process, it is recommended to control the temperature at 40 - 60 °C and the impregnation time at 3 - 8 s to ensure uniform fiber coloring; the oven temperature gradient is preferably controlled in a three - stage manner of 120 - 150 - 100 °C, the wind speed is 8 - 12 m / s, and the residence time is 20 - 40 s; the temperature of the pre - drying cylinder group is 80 - 110 °C, and the line pressure is 20 - 40 kN / m to increase the paper dryness to 65 - 75%; the temperature of the post - drying cylinder decreases step - by - step (95 - 80 - 65 °C) to prevent the glue layer from wrinkling. The line pressure of the calendering process is 50 - 150 kN / m, the roll surface temperature is 60 - 90 °C, and the vehicle speed matches the re - wetting rate of the paper after sizing (±2%); the coiling tension is controlled at 0.8 - 1.5 kN / m to ensure the reel tightness of 650 - 850 kg / m 3 。

[0066] The comparison photos of the oil - proof performance between the obtained dyeing paper and the oil - proof dyeing paper in Example 2 are as Figure 2 shown. The product of Example 2 ( Figure 2 right) has good oil - proof performance; the comparison of other properties is shown in Table 1.

[0067] Comparative Example 2

[0068] For further comparative illustration, in this comparative example, only the paper - based material is subjected to separate oil - proof treatment. Cassava starch, sodium dodecyl sulfate, ammonium persulfate and water are mixed in a mass ratio of 4:6:1:120, and after stirring for 30 min at 80 °C and 300 rpm, dispersion liquid B is obtained. Then, methyl methacrylate, butyl acrylate and methacrylic acid are mixed in a mass ratio of 12:12:1 to obtain monomer mixture C. C is slowly added drop - by - drop to dispersion liquid B, and then reacted with stirring at the above temperature and 600 rpm for 2 h to obtain oil - proof coating D.

[0069] Using the impregnated base paper with a basis weight of 80 g / m 2 and a Cobb value of 137 g / m 2 , through the process of "sizing machine (oil - proof coating D) - post - drying cylinder - calendering - coiling", an oil - proof paper - based material is obtained. Among them, the sizing machine should control the glue liquid concentration at 5 - 12% and the coating amount at 3 - 8 g / m 2 , and the penetration depth of the sizing material needs to reach more than 1 / 3 of the paper thickness; the temperature of the post - drying cylinder decreases step - by - step (95 - 80 - 65 °C) to prevent the glue layer from wrinkling. The line pressure of the calendering process is 50 - 150 kN / m, the roll surface temperature is 60 - 90 °C, and the vehicle speed matches the re - wetting rate of the paper after sizing (±2%); the coiling tension is controlled at 0.8 - 1.5 kN / m to ensure the reel tightness of 650 - 850 kg / m 3 。

[0070] The surface morphologies of the obtained greaseproof paper and the base paper are compared as follows Figure 3 shown in the scanning electron microscope images in the figure. The surface of the base paper ( Figure 3 left) is rough, and there is an obvious porous structure between the fibers. However, the surface of the greaseproof paper becomes uniform and flat, the fiber structure is completely covered by the coating, and at the same time, a dense and smooth film is formed on the surface, and the gaps between the fibers are fully filled; the comparison of other properties is shown in Table 1.

[0071] Table 1 Comparison of the main properties of different embodiments

[0072]

[0073] As can be seen from the above embodiments, the embodiments of the present invention use two different dip coating processes on the same production line to centrally achieve the dyeing, waterproofing (hydrophobic) and oil-proofing treatments of paper-based materials, and overcome the scientific problem that waterproof (hydrophobic) coatings are lipophilic due to their low surface energy under conventional conditions without fluorine, and successfully developed a fluorine-free waterproof and oil-proof dyed paper. The dyed paper produced by the embodiments of the present invention does not fade after being immersed in water for a long time (at least 3 days), and the Cobb value can be as low as 1.0 g / m 2 , the water contact angle is as high as 130°, and the oil-proof grade can reach 8 levels, with excellent waterproof and oil-proof characteristics.

[0074] The above examples are only used to illustrate the technical features and implementation processes of the present invention, rather than limiting the technical solutions of the present invention. It should be pointed out that for those of ordinary skill in the art, the present invention can still be modified or equivalently replaced, and any modification or replacement that does not depart from the principle of the present invention is covered by the protection of the present invention.

Claims

1. A method for producing washable, hydrophobic, oil-proof, fixed-color dyed paper, characterized in that: The following steps are involved: Taking the impregnated base paper as the base material, impregnation, pre-drying, surface sizing and post-drying are carried out in sequence to obtain a washable, hydrophobic, oil-proof and fixed-color dyed paper material; The dyeing is carried out by using a hydrophobic dyeing coating, the hydrophobic dyeing coating comprises a dye, a water-based food-grade hydrophobic color-fixing aid and water, the water-based food-grade hydrophobic color-fixing aid comprises: nano-grade acrylic resin, food-grade fluorine-free trialkoxysilane and hydrophilic nano-silica; the mass ratio of the dye, the water-based food-grade hydrophobic color-fixing aid and water is 1:(1-2):(7-8); The surface sizing is performed using a water-based fluorine-free oil-proof functional coating, which contains starch, an acrylate copolymer and dodecyl sulfate; the water-based fluorine-free oil-proof functional coating is neutral.

2. The manufacturing method according to claim 1, characterized in that: In the hydrophobic dyed coating, the dye is a liquid color paste or a solid dye aqueous dispersion.

3. The manufacturing method according to claim 1, characterized in that: In the water-based food-grade hydrophobic color-fixing auxiliary agent, the solid content of the nano-scale acrylic resin is 35-40%, and the particle size is 40-70 nm.

4. The manufacturing method according to any one of claims 1 to 3, characterized in that: The preparation of the water-based fluorine-free oil-proof functional coating comprises: After starch, dodecyl sulfate and an initiator are mixed, water is added and heated to obtain a dispersion; Methyl methacrylate, butyl acrylate and methacrylic acid are mixed, added into the dispersion, heated for reaction, and the pH value is adjusted to be neutral, thereby obtaining the water-based fluorine-free oil-proof functional coating.

5. The manufacturing method according to claim 4, characterized in that: In the preparation of the water-based fluorine-free oil-proof functional coating, the mass ratio of the starch, dodecyl sulfate and initiator is (3-5): (5-6): 1; the mass ratio of the methyl methacrylate, butyl acrylate and methacrylic acid is (10-12): (10-14): (0.8-1).

6. The manufacturing method according to claim 5, characterized in that: In the preparation of the water-based fluorine-free oil-proof functional coating, the initiator is persulfate; the temperature of the heating reaction is 60-100° C., the time is 1-3 hours, and the pH value is adjusted to 6.8-7.2 with ammonia water.

7. The manufacturing method according to any one of claims 1 to 3, characterized in that: The basis weight of the impregnated base paper is 80-120 g / m 2 , water absorption value is 100~250g / m 2 .

8. The manufacturing method according to claim 7, characterized in that: After the impregnation, the process is oven dried and then pre-dried; the temperatures of the oven drying and pre-drying are 80-150° C. respectively.

9. The hydrophobic, oil-proof, color-fixing dyed paper material obtained by the manufacturing method according to any one of claims 1 to 8, wherein the water absorption value is 2.5 g / m 2 the following.

10. The hydrophobic, oil-proof, color-fixing dyed paper material according to claim 9, characterized in that: The water absorption value of the hydrophobic, oil-proof and color-fixing dyed paper material is 1.0 to 2.3 g / m 2 .

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