A kind of pulp molding moisture-proof paint and suction filtration equipment

Abstract

The present application relates to moisture-proof paint technical field, concretely is a kind of paper pulp molding with moisture-proof paint and filter equipment, comprising: water-based polyurethane emulsion, film-forming aid and leveller are uniformly mixed, obtain mixed solution;Hollow mesoporous silica microspheres, modified nano filler and thickening agent are added to mixed solution, uniformly stirred, and after vacuum defoaming, paper pulp molding with moisture-proof paint is prepared.The present application adds hollow mesoporous silica microspheres and modified nano filler in paint matrix, so that the paint has good air permeability and hydrophobicity.Specifically, the nano filler is hydrophobically modified, and by the dense arrangement of micron-sized hollow mesoporous silica microspheres and nanoscale modified nano filler, a micro-nano rough structure is formed on the surface of the coating, which greatly improves the hydrophobicity and waterproofness of the coating;At the same time, the interspersed hollow mesoporous silica microspheres are beneficial to the transmission of water vapor due to the mesoporous structure, which can timely discharge the water vapor in the paper pulp molding and prevent mold.

Description

Technical Field

[0001] This invention relates to the field of moisture-proof coating technology, specifically to a moisture-proof coating for pulp molding and a filtration device. Background Technology

[0002] Pulp molding is a three-dimensional papermaking technology that uses waste paper as raw material, shaping paper products into specific forms using special molds on a molding machine. It has four main advantages: ① The raw material is waste paper, including cardboard, waste corrugated cardboard, and waste paper scraps, making it widely available; ② The production process involves pulping, adsorption molding, drying, and setting, which is environmentally friendly; ③ It can be recycled and reused; ④ It is smaller in volume than foamed plastics, can be stacked, and is convenient for transportation. Besides being used for lunch boxes and tableware, pulp molding is also rapidly developing as industrial cushioning packaging.

[0003] In practical applications, the quality of molded pulp products is often severely affected when used in high-humidity environments or in direct contact with liquids. Currently, moisture-proof coatings, such as water-based polyurethane coatings, can be evenly sprayed onto the surface of molded pulp products to achieve a waterproof effect; however, the coating formed after the water-based polyurethane coating has poor air permeability, and moisture remaining inside the molded pulp product is difficult to expel, leading to mold growth or even rotting. Based on this, a moisture-proof coating and filtration device for molded pulp are proposed. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a moisture-proof coating for pulp molding and a filtration device. By adding hollow mesoporous silica microspheres and modified nanofillers to the coating matrix, the coating exhibits good air permeability and hydrophobicity.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a moisture-proof coating for pulp molding, comprising the following raw materials in parts by weight: 80-90 parts of waterborne polyurethane emulsion, 10-15 parts of hollow mesoporous silica microspheres, 15-20 parts of modified nanofiller, 2-4 parts of film-forming aid, 1-2 parts of leveling agent, and 0.5-1 parts of thickener.

[0006] Preferably, the hollow mesoporous silica microspheres have a particle size of 1-2 μm and a mesopore diameter of less than 10 nm.

[0007] Preferably, the modified nanofiller is prepared as follows: S1, dodecyltriethoxysilane is dissolved in anhydrous ethanol to obtain a modified solution; S2, the nanofiller is ultrasonically dispersed in the modified solution and reacted for 1.5-2 hours to obtain a reaction material; S3, the reaction material is filtered and then vacuum dried to obtain the modified nanofiller.

[0008] Preferably, the nanofiller is composed of nano-silica and carbon nanofibers in a mass ratio of 3:1; and the diameter of the nano-silica and carbon nanofibers is controlled between 100-150 nm.

[0009] Preferably, in step S1, the volume ratio of the dodecyltriethoxysilane to anhydrous ethanol is 1:(3-4).

[0010] Preferably, the film-forming aid is selected from propylene glycol butyl ether and benzyl alcohol; the leveling agent is selected from cellulose acetate butyrate and polydimethylsiloxane; and the thickener is selected from hydroxypropyl methylcellulose and hydroxyethyl cellulose.

[0011] This invention provides a method for preparing a moisture-proof coating for pulp molding, comprising the following steps: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Hollow mesoporous silica microspheres, modified nanofillers and thickeners are added to the mixture, stirred evenly, and defoamed under vacuum to obtain a moisture-proof coating for pulp molding.

[0012] The present invention also provides a filtration device for moisture-proof coatings, including a conical bottle, a negative pressure pipe connected to the upper part of the side end of the conical bottle, a vacuum pump connected to the other end of the negative pressure pipe, a bottle stopper installed at the mouth of the conical bottle, a connecting pipe installed through the middle of the bottle stopper, a filtration hopper connected to the other end of the connecting pipe, an annular groove opened inside the filtration hopper, a perforated plate arranged inside the groove, an annular rubber sleeve fixed between the top edge of the perforated plate and the top wall of the groove, and at least two sets of power units for driving the perforated plate to vibrate along the circumferential direction of the groove.

[0013] Preferably, the power unit includes a servo motor installed at the outer end of the filter hopper. The output shaft of the servo motor extends out of the groove and is fixed with a circular plate. Several sets of support rods are fixed along the circumference of the circular plate. Rollers are installed at the other end of the support rods. The several sets of rollers take turns hitting the filter plate.

[0014] Preferably, a ring plate is fixed at the bottom end of the leak plate outside its leak hole.

[0015] This invention provides a moisture-proof coating for pulp molding and a filtration device, which have the following advantages compared with the prior art: This invention incorporates hollow mesoporous silica microspheres and modified nanofillers into the coating matrix, resulting in coatings with excellent air permeability and hydrophobicity. Specifically, the nanofillers are hydrophobically modified, and the dense arrangement of micron-sized hollow mesoporous silica microspheres and nano-sized modified nanofillers creates a micro-nano rough structure on the coating surface, significantly improving the coating's hydrophobic and waterproof properties. Simultaneously, the interspersed hollow mesoporous silica microspheres, due to their mesopores, facilitate the permeation of moisture, allowing for timely removal of moisture from the pulp molding process and preventing mold growth. Furthermore, during coating drying and curing, they promote rapid moisture loss, accelerating the curing process.

[0016] The filtration device of this invention starts a servo motor during use, which drives several sets of rollers to rotate. These rollers then collide with the bottom of the filter plate in turn, causing the filter plate and the filter material above it to shake rapidly. This loosens the nano-sized filter material and improves the filtration efficiency of the reaction material. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the structure of the filtration device of the present invention; Figure 2 This is a schematic diagram of the internal structure of the filter bucket of the present invention; Figure 3 For the present invention Figure 2 Enlarged diagram of part A in the middle.

[0018] In the attached diagram: 1-conical flask, 2-stopper, 3-connecting pipe, 4-negative pressure pipe, 5-first flexible hose, 6-vacuum pump, 7-second flexible hose, 8-filter funnel, 9-tank, 10-strainer plate, 11-rubber sleeve, 12-circular plate, 13-support rod, 14-roller, 15-servo motor, 16-ring plate. Detailed Implementation

[0019] The following embodiments are provided to illustrate the implementation of this application in detail, so that the process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0020] Example 1 Because nano-sized fillers have small particle sizes and are prone to agglomeration, they can easily clog filter paper or membranes during filtration, leading to deviations in filtration performance and limiting filtration efficiency. To address this, a filtration device for moisture-proof coatings is provided, comprising a conical flask 1, a negative pressure pipe 4 connected to the upper side of the conical flask 1, a vacuum pump 6 connected to the other end of the negative pressure pipe 4, a stopper 2 installed at the mouth of the conical flask 1, a connecting pipe 3 penetrating the middle of the stopper 2, and a filtration hopper 8 connected to the other end of the connecting pipe 3. The filtration hopper 8 has an annular groove 9 inside, and a perforated plate 10 is installed inside the groove 9. A ring plate 16 is fixed to the bottom of the perforated plate 10 outside its perforation, preventing liquid leaking from the perforation from splashing into the groove 9. An annular rubber sleeve 11 is fixed between the top edge of the perforated plate 10 and the top wall of the groove 9, and at least two sets of power units driving the perforated plate 10 to vibrate are provided along the circumference of the groove 9. The power unit includes a servo motor 15 installed at the outer end of the filter hopper 8. The output shaft of the servo motor 15 extends out of the groove 9 and is fixed with a circular plate 12. Several sets of support rods 13 are fixed along the circumference of the circular plate 12. Rollers 14 are installed at the other end of the support rods 13. The several sets of rollers 14 take turns hitting the filter plate 10.

[0021] In use, filter paper or filter membrane is placed on top of the filter plate 10, and nanoscale reaction material is poured into the filtration hopper 8. The vacuum pump 6 is started, and the servo motor 15 is started during the filtration process to drive the circular plate 12 and its support rod 13 to rotate, thereby driving several sets of rollers 14 to rotate. These rollers then collide with the bottom of the filter plate 10 in turn, causing the filter plate 10 and the filter material above it to shake rapidly, making the nanoscale filter material loose, which is beneficial to improving the filtration efficiency of the reaction material.

[0022] Example 2 The preparation method of the modified nanofiller is as follows: S1. Dissolve dodecyltriethoxysilane in anhydrous ethanol at a volume ratio of 1:4 to obtain the modified solution; S2. The nanofiller is ultrasonically dispersed in the modified liquid and reacted for 1.5 h to obtain the reaction material; wherein the nanofiller is composed of nano-silica and carbon nanofibers in a mass ratio of 3:1; and the diameter of nano-silica and carbon nanofibers is controlled between 100-150 nm. S3. The reaction material is filtered and then dried under vacuum to obtain the modified nanofiller.

[0023] Example 3 The preparation method of the modified nanofiller is as follows: S1. Dissolve dodecyltriethoxysilane in anhydrous ethanol at a volume ratio of 1:3 to obtain the modified solution; S2. The nanofiller is ultrasonically dispersed in the modified liquid and reacted for 2 hours to obtain the reaction material; wherein the nanofiller is composed of nano-silica and carbon nanofibers in a mass ratio of 3:1; and the diameter of nano-silica and carbon nanofibers is controlled between 100-150nm. S3. The reaction material is filtered and then dried under vacuum to obtain the modified nanofiller.

[0024] Example 4 A moisture-proof coating for pulp molding comprises the following raw materials in parts by weight: 90 parts of waterborne polyurethane emulsion, 10 parts of hollow mesoporous silica microspheres (particle size 1-2 μm, mesopore diameter within 10 nm), 20 parts of modified nanofiller (prepared in Example 2), 2 parts of benzyl alcohol, 2 parts of cellulose acetate-butyrate, and 0.5 parts of hydroxyethyl cellulose.

[0025] The preparation method of the above-mentioned moisture-proof coating for pulp molding includes the following steps: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Hollow mesoporous silica microspheres, modified nanofillers and thickeners are added to the mixture, stirred evenly, and defoamed under vacuum to obtain a moisture-proof coating for pulp molding.

[0026] Example 5 A moisture-proof coating for pulp molding comprises the following raw materials in parts by weight: 80 parts of waterborne polyurethane emulsion, 15 parts of hollow mesoporous silica microspheres (particle size 1-2 μm, mesopore diameter within 10 nm), 15 parts of modified nanofiller (prepared in Example 3), 4 parts of propylene glycol butyl ether, 1 part of polydimethylsiloxane, and 1 part of hydroxypropyl methylcellulose.

[0027] The preparation method of the above-mentioned moisture-proof coating for pulp molding includes the following steps: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Hollow mesoporous silica microspheres, modified nanofillers and thickeners are added to the mixture, stirred evenly, and defoamed under vacuum to obtain a moisture-proof coating for pulp molding.

[0028] Example 6 A moisture-proof coating for pulp molding comprises the following raw materials in parts by weight: 85 parts of waterborne polyurethane emulsion, 12 parts of hollow mesoporous silica microspheres (particle size 1-2 μm, mesopore diameter within 10 nm), 18 parts of modified nanofiller (prepared in Example 2), 3 parts of propylene glycol butyl ether, 1.5 parts of polydimethylsiloxane, and 0.6 parts of hydroxyethyl cellulose.

[0029] The preparation method of the above-mentioned moisture-proof coating for pulp molding includes the following steps: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Hollow mesoporous silica microspheres, modified nanofillers and thickeners are added to the mixture, stirred evenly, and defoamed under vacuum to obtain a moisture-proof coating for pulp molding.

[0030] Comparative Example 1 A moisture-proof coating for pulp molding comprises the following raw materials in parts by weight: 85 parts of waterborne polyurethane emulsion, 12 parts of hollow silica microspheres (particle size 1-2 μm), 18 parts of modified nanofiller (prepared in Example 2), 3 parts of propylene glycol butyl ether, 1.5 parts of polydimethylsiloxane, and 0.6 parts of hydroxyethyl cellulose.

[0031] The preparation method of the above-mentioned moisture-proof coating for pulp molding includes the following steps: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Add hollow silica, modified nanofiller and thickener to the mixture, stir evenly, and then defoam under vacuum to obtain a moisture-proof coating for pulp molding.

[0032] Comparative Example 2 A moisture-proof coating for pulp molding comprises the following raw materials in parts by weight: 85 parts of waterborne polyurethane emulsion, 12 parts of modified hollow mesoporous silica microspheres (particle size 1-2 μm, mesopore diameter within 10 nm), 18 parts of modified nanofiller (prepared in Example 2), 3 parts of propylene glycol butyl ether, 1.5 parts of polydimethylsiloxane, and 0.6 parts of hydroxyethyl cellulose.

[0033] The preparation method of modified hollow mesoporous silica microspheres is as follows: S1. Dissolve dodecyltriethoxysilane in anhydrous ethanol at a volume ratio of 1:4 to obtain the modified solution; S2. The hollow mesoporous silica microspheres were ultrasonically dispersed in the modified liquid and reacted for 1.5 h to obtain the reaction material; S3. The reaction material is filtered and then dried under vacuum to obtain modified hollow mesoporous silica microspheres.

[0034] The preparation method of the above-mentioned moisture-proof coating for pulp molding includes the following steps: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Add modified hollow mesoporous silica microspheres, modified nanofillers and thickeners to the mixture, stir evenly, and then defoam under vacuum to obtain a moisture-proof coating for pulp molding.

[0035] Comparative Example 3 A moisture-proof coating for pulp molding comprises the following raw materials in parts by weight: 85 parts of waterborne polyurethane emulsion, 30 parts of modified nanofiller (prepared in Example 2), 3 parts of propylene glycol butyl ether, 1.5 parts of polydimethylsiloxane, and 0.6 parts of hydroxyethyl cellulose.

[0036] The preparation method of the above-mentioned moisture-proof coating for pulp molding includes the following steps: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Add modified nanofiller and thickener to the mixture, stir evenly, and then defoam under vacuum to obtain a moisture-proof coating for pulp molding.

[0037] Comparative Example 4 A moisture-proof coating for pulp molding comprises the following raw materials in parts by weight: 85 parts of waterborne polyurethane emulsion, 30 parts of hollow mesoporous silica microspheres (particle size of 1-2 μm, mesopore diameter within 10 nm), 3 parts of propylene glycol butyl ether, 1.5 parts of polydimethylsiloxane, and 0.6 parts of hydroxyethyl cellulose.

[0038] The preparation method of the above-mentioned moisture-proof coating for pulp molding includes the following steps: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Add hollow mesoporous silica microspheres and thickener to the mixture, stir evenly, and then defoam under vacuum to obtain a moisture-proof coating for pulp molding.

[0039] Comparative Example 5 A moisture-proof coating for pulp molding comprises the following raw materials in parts by weight: 85 parts of waterborne polyurethane emulsion, 3 parts of propylene glycol butyl ether, 1.5 parts of polydimethylsiloxane, and 0.6 parts of hydroxyethyl cellulose.

[0040] The preparation method of the above-mentioned moisture-proof coating for pulp molding includes the following steps: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Add thickener to the mixture, stir evenly, and then defoam under vacuum to obtain a moisture-proof coating for pulp molding.

[0041] Quality Inspection The examples and comparative examples specifically use waterborne polyurethane emulsion 8355.

[0042] 1. The moisture-proof coatings from Examples 4-6 and Comparative Examples 1-5 were brushed onto cardboard and cured to obtain coating samples. The water vapor transmission rate (air permeability) of the coating samples was tested according to the standard GB / T22921-2008 under the conditions of 38°C and 90% humidity. The specific results are shown in Table 1.

[0043] Table 1 Water vapor transmission rate

[0044] 2. The moisture-proof coatings from Examples 4-6 and Comparative Examples 1-5 were brushed onto cardboard and cured to obtain coated samples. Water contact angle tests were then performed. After 100 washes and drying, the water contact angle was tested again. The stability of the coated samples was characterized by the rate of change of the water contact angle before and after washing. The formula for calculating the rate of change is as follows: In the above formula: Indicates the water contact angle of the coated sample before washing; This indicates the water contact angle of the coated sample after washing.

[0045] The specific results are shown in Table 2.

[0046] Table 2 Hydrophobicity and Stability

[0047] Based on Tables 1 and 2, it can be seen that compared with Example 6, the coating sample in Comparative Example 1 still maintains good hydrophobicity, but its air permeability is poor; the coating sample in Comparative Example 2 has a slight improvement in hydrophobicity, but its air permeability is still poor; the coating sample in Comparative Example 3 has reduced hydrophobicity and poor air permeability due to the lack of micro-rough surface structure; the coating sample in Comparative Example 4 has excellent air permeability, but its hydrophobicity is significantly reduced. Compared with Example 6, no hollow mesoporous silica microspheres were added in Comparative Example 3, and no modified nanofiller was added in Comparative Example 4, resulting in stability deviation. This indicates that the combined use of mesoporous silica microspheres and modified nanofiller can further improve the scrub resistance of the coating.

[0048] 3. Divide the reaction mixture from Example 6 into two equal volumes, and filter them separately using the filtration equipment from Example 1 and a traditional Buchner funnel. Filtration is considered complete when the filtrate reaches the specified volume. The specific filtration times are shown in Table 3.

[0049] Table 3 Filtration Time

[0050] As shown in Table 3, compared with the traditional Buchner funnel, the filtration device in Example 1 has a higher filtration efficiency for slurries containing nanoscale fillers.

[0051] In addition, the filter paper was replaced once during the traditional Buchner funnel filtration process.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a moisture-proof coating for pulp molding, characterized in that, The moisture-proof coating comprises the following raw materials in parts by weight: 80-90 parts of water-based polyurethane emulsion, 10-15 parts of hollow mesoporous silica microspheres, 15-20 parts of modified nanofiller, 2-4 parts of film-forming aid, 1-2 parts of leveling agent, and 0.5-1 parts of thickener. The hollow mesoporous silica microspheres have a particle size of 1-2 μm and a mesopore size of less than 10 nm. The modified nanofiller is prepared as follows: S1. Dissolve dodecyltriethoxysilane in anhydrous ethanol to obtain the modified solution; S2. The nanofiller is ultrasonically dispersed in the modified liquid and reacted for 1.5-2 hours to obtain the reaction material; wherein the nanofiller is composed of nano-silica and carbon nanofibers in a mass ratio of 3:

1. S3. The reaction material is filtered and then dried under vacuum to obtain the modified nanofiller. The preparation method of the moisture-proof coating is as follows: (1) Mix the waterborne polyurethane emulsion, film-forming aid and leveling agent evenly to obtain a mixture; (2) Hollow mesoporous silica microspheres, modified nanofillers and thickeners are added to the mixture, stirred evenly, and defoamed under vacuum to obtain a moisture-proof coating for pulp molding. The filtration process employs a filtration device, including a filtration bucket (8). The filtration bucket (8) has an annular groove (9) inside. A perforated plate (10) is installed inside the groove (9). An annular rubber sleeve (11) is fixed between the top edge of the perforated plate (10) and the top wall of the groove (9). The groove (9) is provided with at least two sets of power units that drive the perforated plate (10) to vibrate along the circumferential direction. The power unit includes a servo motor (15) installed at the outer end of the filtration bucket (8). The output shaft of the servo motor (15) extends out of the groove (9) and is fixed with a circular plate (12). Several sets of support rods (13) are fixed along the circumference of the circular plate (12). Rollers (14) are installed at the other end of the support rods (13). Several sets of rollers (14) take turns hitting the perforated plate (10).

2. The method for preparing the moisture-proof coating for pulp molding according to claim 1, characterized in that, The diameter of the nano-silica and carbon nanofibers is controlled between 100-150 nm.

3. The method for preparing the moisture-proof coating for pulp molding according to claim 1, characterized in that, In step S1, the volume ratio of dodecyltriethoxysilane to anhydrous ethanol is 1:(3-4).

4. The method for preparing the moisture-proof coating for pulp molding according to claim 1, characterized in that, The film-forming aid is selected from propylene glycol butyl ether and benzyl alcohol; the leveling agent is selected from cellulose acetate butyrate and polydimethylsiloxane; and the thickener is selected from hydroxypropyl methylcellulose and hydroxyethyl cellulose.

5. The method for preparing the moisture-proof coating for pulp molding according to claim 1, characterized in that, The filtration device includes a conical flask (1), a negative pressure pipe (4) connected to the upper part of the side end of the conical flask (1), a vacuum pump (6) connected to the other end of the negative pressure pipe (4), a bottle stopper (2) installed at the mouth of the conical flask (1), a connecting pipe (3) installed through the middle of the bottle stopper (2), and a filtration hopper (8) connected to the other end of the connecting pipe (3).

6. The method for preparing the moisture-proof coating for pulp molding according to claim 5, characterized in that, The bottom end of the leak plate (10) is fixed with a ring plate (16) outside its leak hole.

Images