A full bamboo fiber oil-proof type paper pulp molded product and a preparation method thereof

Abstract

The application discloses a preparation method of a full-bamboo-fiber oil-proof pulp molded product. The application relates to the technical field of pulp molded products. The method comprises the following steps: processing bamboo pulp board raw materials to obtain long-fiber pulp; adding 3-3.5% of anionic oil-proof agent, 3% of waterproof agent and 0.03% of cationic retention aid into the long-fiber pulp to obtain a mixed pulp with a pulp concentration of 0.5%; forming the mixed pulp into a pulp molded wet blank with a water content of 70-80% through vacuum suction; performing hot-pressing treatment on the wet blank to obtain a semi-finished product with a dryness of greater than 90%; and cutting the edges of the semi-finished product to obtain the full-bamboo-fiber oil-proof pulp molded product. The application improves the oil-proof performance of the product by screening out impurity cells and adding cationic retention aid.

Description

Technical Field

[0001] This invention relates to the field of pulp molding technology, and in particular to an all-bamboo fiber oil-resistant pulp molding product and its preparation method. Background Technology

[0002] Pulp molding products are a type of three-dimensional pulp product made from plant fiber pulp (wood, bamboo, reed, sorghum, straw pulp, etc.) or recycled pulp from waste paper as the base material, with the addition of specialized processes and additives, and vacuum-formed on a special molding die (also called a water mold or wire mold). Although my country's pulp molding industry started relatively late, its development and changes have been rapid. In terms of product types, it has evolved from simple, low-end products like egg trays and fruit trays to exquisite industrial and food packaging. In terms of technology, it has progressed from simple recycling of waste paper to high-end disposable tableware products that meet the requirements of being waterproof, oil-proof, safe, non-toxic, odorless, and easy to use. Therefore, my country has reached a world-class level in certain performance indicators of pulp molding production processes and equipment. Furthermore, the production process of pulp molding products does not generate other waste, and the products can be easily recycled after consumption at a low cost. Even the non-recyclable portions can degrade on their own, making it a truly "green and environmentally friendly material."

[0003] However, existing research shows that bamboo fiber pulp molding still faces many performance challenges. Bamboo fiber contains a high content of impurities, including thin-walled cells, epidermal cells, and vessels, which negatively impact the physical properties of the paper product, leading to insufficient strength in the final product. Specifically, bamboo fiber pulp molding products exhibit lower bursting index, tearing index, and tensile strength, limiting their application in applications requiring high strength. Furthermore, bamboo fiber has poor hydrophobicity, resulting in inadequate water and oil resistance, necessitating increased use of additives, thus raising production costs and reducing the product's market competitiveness. While bamboo fiber holds great potential in pulp molding, its high impurity content, insufficient strength, and poor water and oil resistance remain unresolved issues. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing a whole bamboo fiber oil-resistant pulp molding product and its preparation method.

[0005] The present invention provides a method for preparing an oil-resistant bamboo fiber pulp molding product, comprising the following steps: processing bamboo pulp board raw material to obtain long fiber pulp;

[0006] Long fiber pulp is mixed with 3%–3.5% anionic oil repellent, 3% waterproofing agent, and 0.03% cationic retention aid to obtain a pulp concentrate with a concentration of 0.5%.

[0007] The prepared pulp is vacuum-formed to obtain a pulp molding wet blank with a moisture content of 70% to 80%. The wet blank is then hot-pressed to obtain a semi-finished product with a dryness of more than 90%. After trimming, an all-bamboo fiber oil-resistant pulp molding product is obtained.

[0008] Furthermore, the cationic retention aid is one or more of cationic polyacrylamide and cationic polydimethyldiallyl ammonium chloride.

[0009] Furthermore, the waterproofing agent is an alkyl ketene dimer.

[0010] Furthermore, the vacuum suction time is 15 seconds, and the vacuum degree is 0.06 MPa.

[0011] Furthermore, the wet blank is transferred to a hot press mold for hot pressing. The upper mold temperature is 160°C and the lower mold temperature is 170°C, and the time is controlled at 60 seconds.

[0012] Furthermore, the specific steps for processing bamboo pulp board raw materials into long fiber pulp are as follows:

[0013] Soak the bamboo pulp board for more than 4 hours;

[0014] The soaked pulp board is sent to the Wali pulping machine for dissolution to obtain wet pulp of a certain concentration;

[0015] The resulting wet slurry is then prepared to a concentration of 0.2% to 0.3%.

[0016] The obtained slurry is screened through a sieve.

[0017] The sieved long fibers are formulated to a certain mass concentration and then refined using a PFI refiner to cause the fiber cell walls to fray, tear, and fracture, thus producing long fiber pulp.

[0018] Furthermore, the slurry is sieved through a 14-mesh sieve.

[0019] An oil-resistant bamboo fiber pulp molding product prepared using the above-described preparation method.

[0020] This invention improves the oil resistance of molded products by sieving out impurities and adding cationic retention aids. Using 100% bamboo pulp as raw material, appropriate screening methods are employed to remove impurities, significantly increasing the purity of the pulp fibers. By sieving out some impurities and short fibers while retaining long fibers, the impact of impurities and short fibers on the oil resistance of molded bamboo pulp products is eliminated at the source. This not only improves the oil resistance level but also strengthens the bond between fibers, enhancing the product's strength and durability. Furthermore, it reduces the amount of additives needed, thereby lowering production costs and improving the product's economic efficiency.

[0021] To ensure that the oil-repellent and water-repellent agents effectively adhere to the fibers, this invention adds an appropriate amount of cationic retention aid to the system. The positively charged cationic aid (e.g., CPAM, PDADMAC, etc.) bridges the fibers and the negatively charged oil-repellent agents, improving the adhesion of the oil-repellent agents to the fiber surface and reducing their loss. This not only reduces the consumption of chemicals but also further improves the oil-repellent rating of bamboo fiber products, enhances quality, and reduces production costs.

[0022] In actual factory production, the high content of impurities in bamboo pulp leads to increased use of oil-resistant agents during pulp molding, resulting in higher costs. This invention proposes for the first time to remove some impurities through fiber grading and to add an appropriate amount of cationic retention aids (e.g., CPAM, PDADMAC, etc.) to the graded bamboo pulp, allowing the oil-resistant agent to adhere more effectively to the fibers. This combined approach reduces the amount of oil-resistant agent used and lowers costs.

[0023] Impurities in bamboo pulp are a major factor affecting the strength of molded pulp products. The higher the impurity content in bamboo pulp, the higher the freeness and the worse the water filtration performance. Under the same freeness conditions, higher impurity content leads to a decrease in the bursting index, tear index, tensile strength, elongation at break, and folding endurance of the bamboo pulp. This invention proposes for the first time a method of removing some impurities through fiber grading to increase bamboo pulp strength and improve product quality.

[0024] This invention uses 100% bamboo fiber as the raw material for pulp molding, replacing wood with bamboo, which is of great significance for environmental protection and forest conservation, and makes full use of other fast-growing non-wood plant fiber resources. Furthermore, it has low recycling costs, and the non-recyclable portion can degrade on its own, making it a truly "green and environmentally friendly material". Attached Figure Description

[0025] Figure 1 An optical microscope image of short fibers and mixed cells;

[0026] Figure 2 This is an optical microscope image of a long fiber.

[0027] Figure 3 This is a statistical chart of fiber distribution before screening;

[0028] Figure 4 This is a statistical chart of fiber distribution after screening. Detailed Implementation

[0029] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0030] Example 1

[0031] The experimental steps are as follows:

[0032] (1) Soak the bamboo pulp board for more than 4 hours.

[0033] (2) The soaked pulp board in step (1) is sent to the Wali pulping machine for decomposition to obtain a wet pulp with a concentration of 1.57%.

[0034] (3) Prepare the wet slurry obtained in step (2) into a slurry with a concentration of 0.2% to 0.3%.

[0035] (4) The pulp obtained in step (3) is sieved through a 14-mesh sieve, repeated twice. The pulp above the sieve is long fiber pulp, and the pulp below the sieve is mixed cells and short fiber pulp. See [link to fiber morphology and distribution] for details. Figures 1-4 The freeness was measured separately, and the results are shown in Table 1.

[0036] (5) The long fibers after sieving are prepared to a mass concentration of 10wt%, and then refined using a PFI refiner to cause the fiber cell walls to fray, tear, and fracture, thus obtaining bamboo fiber with a beating degree of 35°SR.

[0037] (6) The strength index of the pulped bamboo fiber was tested. The results are shown in Table 3.

[0038] (7) Dilute the reagent with deionized water at a ratio of 1:20. Add 3% oil repellent, 3% water repellent, and 0.03% retention aid to the long fiber pulp after beating. Adjust the pulp consistency to 0.5% with water to obtain bamboo fiber pulp for pulp molding. Measure the oil repellency value. The results are shown in Table 2.

[0039] (8) A pulp molding machine is used to form a pulp molded blank with a moisture content of 70% to 80% by vacuum suction molding (suction time 15s, vacuum degree 0.06Mpa). The wet blank is transferred to a hot press mold for heat treatment. The hot press temperature is set to 160℃ for the upper mold and 170℃ for the lower mold, and the time is controlled at 60s to obtain a semi-finished product with a dryness of more than 90%. After the dried semi-finished product is cooled, it is then trimmed by a paper mold trimming machine to finally obtain a whole bamboo fiber pulp molded product.

[0040] from Figures 1-4 It can be seen that fiber grading can reduce the content of impurities and short fibers, and the proportion of long fibers after sieving is higher and the average length is longer.

[0041] Example 2

[0042] The experimental steps are as follows:

[0043] (1) Soak the bamboo pulp board raw material for more than 4 hours.

[0044] (2) The soaked pulp board in step (1) is sent to the Wali pulping machine for decomposition to obtain a wet pulp with a concentration of 1.57%.

[0045] (3) Prepare the wet slurry obtained in step (2) into a slurry with a concentration of 0.2% to 0.3%.

[0046] (4) The pulp obtained in step (3) is screened through a 14-mesh sieve. This process is repeated twice. The pulp on the sieve is long fiber pulp, while the pulp below the sieve is mixed cells and short fiber pulp.

[0047] (5) The long fibers after sieving are prepared to a mass concentration of 10wt%, and then refined using a PFI refiner to cause the fiber cell walls to fray, tear, and fracture, thus obtaining bamboo fiber with a beating degree of 35°SR.

[0048] (6) Dilute the reagent with deionized water at a ratio of 1:20. Add 3.5% oil repellent, 3% water repellent, and 0.03% retention aid to the beaten long fiber pulp, and adjust the pulp consistency to 0.5% with water to obtain bamboo fiber pulp for pulp molding. Measure the oil repellency value. The results are shown in Table 2. Perform strength index testing, and the results are shown in Table 3.

[0049] (7) The prepared pulp is molded by a pulp molding machine, using vacuum suction molding with a suction time of 15s and a vacuum degree of 0.06MPa to obtain a pulp molding wet blank with a moisture content of 70% to 80%. The wet blank is transferred to a hot press mold for heat treatment. The hot press temperature is set to 160℃ for the upper mold and 170℃ for the lower mold, and the time is controlled at 60s to obtain a semi-finished product with a dryness of more than 90%. After the dried semi-finished product is cooled, it is then trimmed by a paper mold trimming machine to finally obtain a 100% bamboo pulp molded product.

[0050] Comparative Example 1

[0051] The experimental steps are as follows:

[0052] (1) Soak the bamboo pulp board raw material for more than 4 hours.

[0053] (2) The soaked pulp board from step (1) was sent to the Wali pulper for dissolution to obtain a wet pulp with a concentration of 1.57%. The degree of freeness was measured, and the results are shown in Table 1.

[0054] (3) The strength index of bamboo fiber was tested. The results are shown in Table 3.

[0055] (4) Dilute the reagent with deionized water at a ratio of 1:20. Add 3% oil repellent and 3% water repellent to the beaten bamboo fiber, and adjust the pulp consistency to 0.5% with water to obtain bamboo fiber pulp for paper molding. Measure the oil repellency value. The results are shown in Table 2.

[0056] (5) The prepared pulp is molded by a pulp molding machine, using vacuum suction molding with a suction time of 15s and a vacuum degree of 0.06MPa to obtain a pulp molding wet blank with a moisture content of 70% to 80%. The wet blank is transferred to a hot press mold for heat treatment. The hot press temperature is set to 160℃ for the upper mold and 170℃ for the lower mold, and the time is controlled at 60s to obtain a semi-finished product with a dryness of more than 90%. After the dried semi-finished product is cooled, it is then trimmed by a paper mold trimming machine to finally obtain a 100% bamboo pulp molded product.

[0057] Comparative Example 2

[0058] The experimental steps are as follows:

[0059] (1) Soak the bamboo pulp board raw material for more than 4 hours.

[0060] (2) The soaked pulp board in step (1) is sent to the Wali pulping machine for decomposition to obtain a wet pulp with a concentration of 1.57%.

[0061] (3) Bamboo fiber was prepared to a mass concentration of 10wt%, and was refined using a PFI refiner to cause the fiber cell walls to fray, tear, and fracture, resulting in bamboo fiber with a beating degree of 35°SR. Strength index was tested, and the results are shown in Table 3.

[0062] (4) Dilute the reagent with deionized water at a ratio of 1:20. Add 3% oil repellent and 3% water repellent to the pulped bamboo fiber to obtain bamboo fiber pulp for paper molding. Measure the oil repellency value. The results are shown in Table 2.

[0063] (5) The prepared pulp is molded by a pulp molding machine, using vacuum suction molding with a suction time of 15s and a vacuum degree of 0.06MPa to obtain a pulp molding wet blank with a moisture content of 70% to 80%. The wet blank is transferred to a hot press mold for heat treatment. The hot press temperature is set to 160℃ for the upper mold and 170℃ for the lower mold, and the time is controlled at 60s to obtain a semi-finished product with a dryness of more than 90%. After the dried semi-finished product is cooled, it is then trimmed by a paper mold trimming machine to finally obtain a 100% bamboo pulp molded product.

[0064] Comparative Example 3

[0065] The experimental steps are as follows:

[0066] (1) Soak the bamboo pulp board raw material for more than 4 hours.

[0067] (2) The soaked pulp board in step (1) is sent to the Wali pulping machine for decomposition to obtain a wet pulp with a concentration of 1.57%.

[0068] (3) Bamboo fiber is prepared to a mass concentration of 10wt%, and then refined using a PFI refiner to cause the fiber cell walls to fray, tear, and defilamentize, thus obtaining bamboo fiber with a beating degree of 35°SR.

[0069] (4) Dilute the reagent with deionized water at a ratio of 1:20. Add 3.5% oil repellent and 3% water repellent to the pulped bamboo fiber, measure the oil repellency value, and the results are shown in Table 2.

[0070] (5) The prepared pulp is molded by a pulp molding machine, using vacuum suction molding with a suction time of 15s and a vacuum degree of 0.06MPa to obtain a pulp molding wet blank with a moisture content of 70% to 80%. The wet blank is transferred to a hot press mold for heat treatment. The hot press temperature is set to 160℃ for the upper mold and 170℃ for the lower mold, and the time is controlled at 60s to obtain a semi-finished product with a dryness of more than 90%. After the dried semi-finished product is cooled, it is then trimmed by a paper mold trimming machine to finally obtain a 100% bamboo pulp molded product.

[0071] Comparative Example 4

[0072] The experimental steps are as follows:

[0073] (1) Soak the bamboo pulp board raw material for more than 4 hours.

[0074] (2) The soaked pulp board in step (1) is sent to the Wali pulping machine for decomposition to obtain a wet pulp with a concentration of 1.57%.

[0075] (3) Prepare the wet slurry obtained in step (2) into a slurry with a concentration of 0.2% to 0.3%.

[0076] (4) The pulp obtained in step (3) is screened through a 14-mesh sieve. This process is repeated twice. The pulp on the sieve is long fiber pulp, while the pulp below the sieve is mixed cells and short fiber pulp.

[0077] (5) The long fibers after sieving are prepared to a mass concentration of 10wt%, and then refined using a PFI refiner to cause the fiber cell walls to fray, tear, and fracture, thus obtaining bamboo fiber with a beating degree of 35°SR.

[0078] (6) Dilute the reagent with deionized water at a ratio of 1:20. Add 3% oil repellent and 3% water repellent to the long fiber pulp after beating, and adjust the pulp consistency to 0.5% with water to obtain bamboo fiber pulp for pulp molding. Measure the oil repellency value. The results are shown in Table 2.

[0079] (7) The prepared pulp is molded by a pulp molding machine, using vacuum suction molding with a suction time of 15s and a vacuum degree of 0.06MPa to obtain a pulp molding wet blank with a moisture content of 70% to 80%. The wet blank is transferred to a hot press mold for heat treatment. The hot press temperature is set to 160℃ for the upper mold and 170℃ for the lower mold, and the time is controlled at 60s to obtain a semi-finished product with a dryness of more than 90%. After the dried semi-finished product is cooled, it is then trimmed by a paper mold trimming machine to finally obtain a 100% bamboo pulp molded product.

[0080] Comparative Example 5

[0081] The experimental steps are as follows:

[0082] (1) Soak the bamboo pulp board raw material for more than 4 hours.

[0083] (2) The soaked pulp board in step (1) is sent to the Wali pulping machine for decomposition to obtain a wet pulp with a concentration of 1.57%.

[0084] (3) Prepare the wet slurry obtained in step (2) into a slurry with a concentration of 0.2% to 0.3%.

[0085] (4) The pulp obtained in step (3) is screened through a 14-mesh sieve. This process is repeated twice. The pulp on the sieve is long fiber pulp, while the pulp below the sieve is mixed cells and short fiber pulp.

[0086] (5) The long fibers after sieving are prepared to a mass concentration of 10wt%, and then refined using a PFI refiner to cause the fiber cell walls to fray, tear, and fracture, thus obtaining bamboo fiber with a beating degree of 35°SR.

[0087] (6) Dilute the reagent with deionized water at a ratio of 1:20. Add 3.5% oil repellent and 3% water repellent to the beaten long fiber pulp, and adjust the pulp consistency to 0.5% with water to obtain bamboo fiber pulp for pulp molding. Measure the oil repellency value. The results are shown in Table 2. Perform strength index testing, and the results are shown in Table 3.

[0088] (7) The prepared pulp is molded by a pulp molding machine, using vacuum suction molding with a suction time of 15s and a vacuum degree of 0.06MPa to obtain a pulp molding wet blank with a moisture content of 70% to 80%. The wet blank is transferred to a hot press mold for heat treatment. The hot press temperature is set to 160℃ for the upper mold and 170℃ for the lower mold, and the time is controlled at 60s to obtain a semi-finished product with a dryness of more than 90%. After the dried semi-finished product is cooled, it is then trimmed by a paper mold trimming machine to finally obtain a 100% bamboo pulp molded product.

[0089] Table 1. Results of freeness measurement

[0090]

[0091] Table 2. Results of oil resistance test on samples

[0092] Example 1 5 Example 2 7 Comparative Example 1 0 Comparative Example 2 1 Comparative Example 3 4 Comparative Example 4 4 Comparative Example 5 6

[0093] Table 3 Results of Sample Strength Index Testing

[0094]

[0095] As can be seen from Table 1, the short fiber pulp and impurities removed by screening have a high degree of beating and poor water permeability. The degree of beating after removing impurities is lower than that before screening, which proves that removing some impurities is beneficial to improving the water permeability of bamboo pulp.

[0096] As shown in Table 2, when the oil repellent content is 3% and 3.5%, the oil repellent value of the samples after removing impurities is greater than that of the samples before removing impurities, proving that removing some impurities can improve the oil repellent value of bamboo pulp. After adding retention aid, the oil repellent level of the samples is improved, proving that retention aid can effectively adhere the oil repellent and waterproofing agent to the fiber, thereby improving the oil repellent performance of the product.

[0097] By combining pulping, screening to remove impurities, and adding retention aids, the oil resistance level was improved by 5 levels when the oil resistance agent content was 3%. Therefore, the amount of oil resistance agent used can be significantly reduced in actual production.

[0098] As shown in Table 3, after removing some impurities, the bursting index, tear index, and tensile strength of the paper were all higher than the corresponding values ​​of the bamboo pulp before removing impurities, and showed a significant improvement compared to the untreated bamboo pulp, proving that removing some impurities can improve the physical properties of bamboo pulp. Moreover, as can be seen from Comparative Examples 2 and 5, the physical properties of the samples were also improved after adding retention aids.

[0099] For any points not covered above, existing technologies shall apply.

[0100] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an all-bamboo fiber oil-resistant pulp molding product, characterized in that: The process includes the following steps: processing bamboo pulp board raw materials to obtain long fiber pulp; Long fiber pulp is mixed with 3%~3.5% anionic oil repellent, 3% waterproofing agent, and 0.03% cationic retention aid to obtain a pulp consistency of 0.5%. The prepared pulp is vacuum-formed to obtain a pulp molding wet blank with a moisture content of 70% to 80%. The wet blank is then hot-pressed to obtain a semi-finished product with a dryness of more than 90%. After trimming, an all-bamboo fiber oil-resistant pulp molding product is obtained. The cationic retention aid is one or more of cationic polyacrylamide and cationic polydimethyldiallyl ammonium chloride; The waterproofing agent is an alkyl ketene dimer; The specific steps for processing bamboo pulp board raw materials to obtain long fiber pulp are as follows: Soak the bamboo pulp board for more than 4 hours; The soaked pulp board is sent to the Wali pulping machine for dissolution to obtain wet pulp of a certain concentration; The obtained wet slurry is then prepared to a concentration of 0.2% to 0.3%. The obtained slurry is screened through a sieve. The sieved long fibers are formulated to a certain mass concentration and then refined using a PFI refiner to cause the fiber cell walls to fray, tear, and fracture, thus producing long fiber pulp. The slurry was sieved through a 14-mesh sieve.

2. The preparation method according to claim 1, characterized in that: The vacuum suction time is 15 seconds, and the vacuum degree is 0.06 MPa.

3. The preparation method according to claim 1, characterized in that: The wet blank is transferred to a hot press mold for hot pressing. The upper mold temperature is 160℃ and the lower mold temperature is 170℃, and the time is controlled at 60s.

4. A whole bamboo fiber oil-resistant pulp molding product prepared by the preparation method according to any one of claims 1-3.

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