A waterproof pulp molding material and its preparation method

Abstract

This invention provides a waterproof pulp molding material, its preparation method, and its application. The waterproof pulp molding material comprises a bamboo-wood mixed pulp, hydrophobically modified chitosan, hydrophobically modified cyclodextrin, a sizing agent, and a retention aid. This invention modifies the hydrophilic groups on the surfaces of chitosan and cyclodextrin by adding hydrophobically modified chitosan and cyclodextrin to the pulp molding material. This is achieved through hydrophobic modification of the hydroxyl and amino groups on the chitosan surface using short-chain heptafluorobutyric acid (HFA) and AKD, and hydrophobic modification of the hydroxyl groups on the cyclodextrin surface using AKD. Simultaneously, the synergistic effect of these two modifiers results in a final pulp molding material with excellent waterproof performance, Cobb60 < 8 g / m³. 2 The static water contact angle is >125°. After standing in hot water for 30 minutes, there is no seepage, leakage, or deformation on the back of the sample, which greatly expands the application of pulp molding materials in the field of waterproof packaging.

Description

Technical Field

[0001] This invention relates to the field of pulp molding materials, and in particular to a waterproof pulp molding material and its preparation method. Background Technology

[0002] Pulp molding materials, as a new type of environmentally friendly packaging material, have received widespread attention and application globally in recent years. They are three-dimensional paper products made from waste paper and plant fibers (such as bagasse, bamboo fiber, wheat straw, rice straw, reeds, and other renewable resources) through a series of processes including pulping, molding, and drying.

[0003] Based on the different raw materials, existing pulp molding materials can be mainly divided into the following categories:

[0004] Waste paper pulp molding materials: These are made from recycled waste paper through processing. These materials are inexpensive, contribute to resource recycling, and reduce environmental pollution from landfills and incineration.

[0005] Plant fiber molding materials: These materials are made from plant fibers such as sugarcane bagasse, bamboo fiber, and wheat straw. They not only have excellent physical properties, such as high strength and good toughness, but also fully meet environmental protection requirements and are biodegradable.

[0006] Composite pulp molding material: Combining the advantages of waste paper pulp and plant fiber, it is processed through special technology to improve the overall performance of the material, such as enhancing water resistance and oil resistance.

[0007] Pulp molding materials, with their unique environmental friendliness, biodegradability, cushioning properties, and good air permeability, have shown great application potential in many fields such as packaging, tableware, agriculture, and construction.

[0008] Despite the many advantages of pulp molding materials, their poor waterproof performance due to their natural hydrophilicity, which is mainly composed of plant fibers, limits their application in certain areas requiring waterproofing and moisture protection.

[0009] Therefore, developing a pulp molding material with excellent waterproof performance to address the problems existing in the current technology is of practical significance and economic value, and can further promote the sustainable and healthy development of the pulp molding material industry. Summary of the Invention

[0010] In view of the shortcomings of the prior art, one object of the present invention is to provide a pulp molding material with excellent waterproof performance and its preparation method, aiming to solve the technical problem of poor waterproof performance of existing pulp molding materials.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A waterproof pulp molding material, comprising the following components and their parts by weight:

[0013] 60-80 parts of bamboo and wood mixed pulp

[0014] 10-15 parts of chitosan with hydrophobic modification

[0015] 3-10 parts of hydrophobically modified cyclodextrin

[0016] 1-3 parts of sizing agent

[0017] 0.1-0.5 parts of retention aid.

[0018] The bamboo-wood mixed pulp is obtained by mixing 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp;

[0019] The mass ratio of the hydrophobically modified chitosan to the hydrophobically modified cyclodextrin is (2-5):1;

[0020] The hydrophobically modified chitosan is a chitosan co-modified with heptafluorobutyric acid and alkyl ketene dimer AKD, and its specific preparation method is as follows:

[0021] (1) Dissolve an appropriate amount of chitosan and heptafluorobutyric acid in the organic solvent dimethyl sulfoxide with a solid content of 20wt%. Add dehydrating agent EDC·HCl and react at 40-60℃ in the dark for 15-30h. After centrifugation, filtration, alcohol washing and drying, heptafluorobutyric acid modified chitosan is obtained.

[0022] (2) Heptafluorobutyric acid modified chitosan and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 60-80℃ for 5-8 h. After centrifugation, filtration, alcohol washing and drying, hydrophobically modified chitosan was obtained.

[0023] The molar ratio of heptafluorobutyric acid, alkyl ketone dimer AKD and chitosan is (3-5):(5-7):1; the molar ratio of heptafluorobutyric acid to dehydrating agent EDC·HCl is 1:3.

[0024] The hydrophobically modified cyclodextrin is an alkyl ketene dimer modified with AKD, and its specific preparation method is as follows:

[0025] Cyclodextrin and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 60-80℃ for 5-8 h. After centrifugation, filtration, alcohol washing, and drying, hydrophobically modified cyclodextrin was obtained.

[0026] The molar ratio of alkyl ketene dimer AKD to cyclodextrin is (8-10):1.

[0027] The sizing agent is selected from one or more of anionic dispersed rosin gum, cationic dispersed rosin gum, and alkyl ketene dimer AKD;

[0028] The retention aid is selected from one or more of cationic polyacrylamide, anionic polyacrylamide, amphoteric polyacrylamide, and polyethyleneimine.

[0029] A second objective of this invention is to provide a method for preparing a waterproof pulp molding material, comprising the following steps:

[0030] S1. Weigh the raw materials according to the following proportions by weight: bamboo and wood mixed pulp, hydrophobically modified chitosan, hydrophobically modified cyclodextrin, sizing agent and retention aid;

[0031] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for a period of time, and then tap water is added to dilute it to a certain pulp concentration. Then, the hydrophobically modified chitosan, the hydrophobically modified cyclodextrin, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 15-30 minutes after being added before adding the next component.

[0032] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5-10 min, and dry at 100-120℃ for 30 min to obtain semi-finished pulp molding material;

[0033] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5-8 minutes to obtain the pulp molding material.

[0034] Preferably, the disintegration time in step S2 is 5-20 min, and the slurry concentration after dilution is 5wt%-10wt%.

[0035] A third objective of this invention is to provide an application of a waterproof pulp molding material in the field of waterproof packaging.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] (1) This invention creatively incorporates hydrophobically modified chitosan and hydrophobically modified cyclodextrin into pulp molding materials using an in-sizing method. On the one hand, it utilizes the waterproof properties of the chitosan and cyclodextrin structures themselves. On the other hand, it modifies the hydrophilic groups on the surfaces of chitosan and cyclodextrin by hydrophobically modifying the hydroxyl and amino groups on the surface of chitosan with heptafluorobutyric acid and AKD, and by hydrophobically modifying the hydroxyl groups on the surface of cyclodextrin with AKD. This results in a final pulp molding material with excellent waterproof properties, Cobb60 < 8 g / m³. 2 The static water contact angle is >125°. After standing in hot water for 30 minutes, there is no seepage, leakage, or deformation on the back of the sample.

[0038] (2) The present invention creatively discovers that the addition of hydrophobically modified chitosan and hydrophobically modified cyclodextrin to pulp molding materials produces a synergistic effect, which together improves the waterproof performance of pulp molding materials. Detailed Implementation

[0039] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0040] Unless otherwise specified, the terms used in this specification have the same meaning as those commonly understood by those skilled in the art; however, in the event of any conflict, the definitions in this specification shall prevail.

[0041] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0042] The raw materials are selected as follows:

[0043] Bamboo pulp and chemical pulp: Luzhou Yongfeng, bamboo pulp and chemical pulp;

[0044] Softwood chemical pulp: Zhejiang Zhongyi Paper Co., Ltd., bleached softwood pulp;

[0045] Chitosan: Shanghai Aladdin Biochemical Technology Co., Ltd., degree of deacetylation ≥95%, viscosity 100~200mPa·s;

[0046] Cyclodextrin: Qianhui Biotechnology, CAS NO.: 7585-39-9;

[0047] Heptafluorobutyric acid: Shanghai Maclean, CAS NO.:375-22-4;

[0048] Sizing agent: Qingzhou Jinhao New Materials Co., Ltd., alkyl ketene dimer AKD;

[0049] Retention aid: cationic polyacrylamide, Xinqi Chemical.

[0050] Preparation of chitosan with hydrophobic modification

[0051] Preparation Example 1

[0052] Preparation of chitosan SK1 with hydrophobic modification:

[0053] (1) Dissolve an appropriate amount of chitosan and heptafluorobutyric acid in the organic solvent dimethyl sulfoxide with a solid content of 20wt%. Add dehydrating agent EDC·HCl and react at 40℃ in the dark for 20h. After centrifugation and filtration, wash three times with anhydrous ethanol and vacuum dry at 85℃ for 3h, obtain heptafluorobutyric acid modified chitosan.

[0054] (2) Heptafluorobutyric acid modified chitosan and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 6 h, centrifuged and filtered, washed three times with anhydrous ethanol, and vacuum dried at 85 °C for 3 h to obtain hydrophobically modified chitosan.

[0055] The molar ratio of heptafluorobutyric acid, alkyl ketone dimer AKD, and chitosan is 3:5:1; the molar ratio of heptafluorobutyric acid to dehydrating agent EDC·HCl is 1:3.

[0056] Preparation Example 2

[0057] Preparation of chitosan SK2 with hydrophobic modification:

[0058] (1) Dissolve an appropriate amount of chitosan and heptafluorobutyric acid in the organic solvent dimethyl sulfoxide with a solid content of 20wt%. Add dehydrating agent EDC·HCl and react at 40℃ in the dark for 20h. After centrifugation and filtration, wash three times with anhydrous ethanol and vacuum dry at 85℃ for 3h, obtain heptafluorobutyric acid modified chitosan.

[0059] (2) Heptafluorobutyric acid modified chitosan and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 6 h, centrifuged and filtered, washed three times with anhydrous ethanol, and vacuum dried at 85 °C for 3 h to obtain hydrophobically modified chitosan.

[0060] The molar ratio of heptafluorobutyric acid, alkyl ketone dimer AKD, and chitosan is 3:7:1; the molar ratio of heptafluorobutyric acid to dehydrating agent EDC·HCl is 1:3.

[0061] Preparation Example 3

[0062] Preparation of hydrophobically modified chitosan SK3:

[0063] (1) Dissolve an appropriate amount of chitosan and heptafluorobutyric acid in the organic solvent dimethyl sulfoxide with a solid content of 20wt%. Add dehydrating agent EDC·HCl and react at 40℃ in the dark for 20h. After centrifugation and filtration, wash three times with anhydrous ethanol and vacuum dry at 85℃ for 3h, obtain heptafluorobutyric acid modified chitosan.

[0064] (2) Heptafluorobutyric acid modified chitosan and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 6 h, centrifuged and filtered, washed three times with anhydrous ethanol, and vacuum dried at 85 °C for 3 h to obtain hydrophobically modified chitosan.

[0065] The molar ratio of heptafluorobutyric acid, alkyl ketone dimer AKD, and chitosan is 5:5:1; the molar ratio of heptafluorobutyric acid to dehydrating agent EDC·HCl is 1:3.

[0066] Preparation Example 4

[0067] Preparation of chitosan SK4 with hydrophobic modification:

[0068] (1) Dissolve an appropriate amount of chitosan and heptafluorobutyric acid in the organic solvent dimethyl sulfoxide with a solid content of 20wt%. Add dehydrating agent EDC·HCl and react at 40℃ in the dark for 20h. After centrifugation and filtration, wash three times with anhydrous ethanol and vacuum dry at 85℃ for 3h, obtain heptafluorobutyric acid modified chitosan.

[0069] (2) Heptafluorobutyric acid modified chitosan and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 6 h, centrifuged and filtered, washed three times with anhydrous ethanol, and vacuum dried at 85 °C for 3 h to obtain hydrophobically modified chitosan.

[0070] The molar ratio of heptafluorobutyric acid, alkyl ketone dimer AKD, and chitosan is 5:7:1; the molar ratio of heptafluorobutyric acid to dehydrating agent EDC·HCl is 1:3.

[0071] Comparative Preparation Example 1

[0072] Preparation of chitosan SK-C1 with hydrophobic modification:

[0073] (1) Dissolve an appropriate amount of chitosan and heptafluorobutyric acid in the organic solvent dimethyl sulfoxide with a solid content of 20wt%. Add dehydrating agent EDC·HCl and react at 40℃ in the dark for 20h. After centrifugation and filtration, wash three times with anhydrous ethanol and vacuum dry at 85℃ for 3h, obtain heptafluorobutyric acid modified chitosan.

[0074] (2) Heptafluorobutyric acid modified chitosan and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 6 h, centrifuged and filtered, washed three times with anhydrous ethanol, and vacuum dried at 85 °C for 3 h to obtain hydrophobically modified chitosan.

[0075] The molar ratio of heptafluorobutyric acid, alkyl ketone dimer AKD, and chitosan is 2:5:1; the molar ratio of heptafluorobutyric acid to dehydrating agent EDC·HCl is 1:3.

[0076] Comparative Preparation Example 2

[0077] Preparation of chitosan SK-C2 with hydrophobic modification:

[0078] (1) Dissolve an appropriate amount of chitosan and heptafluorobutyric acid in the organic solvent dimethyl sulfoxide with a solid content of 20wt%. Add dehydrating agent EDC·HCl and react at 40℃ in the dark for 20h. After centrifugation and filtration, wash three times with anhydrous ethanol and vacuum dry at 85℃ for 3h, obtain heptafluorobutyric acid modified chitosan.

[0079] (2) Heptafluorobutyric acid modified chitosan and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 6 h, centrifuged and filtered, washed three times with anhydrous ethanol, and vacuum dried at 85 °C for 3 h to obtain hydrophobically modified chitosan.

[0080] The molar ratio of heptafluorobutyric acid, alkyl ketone dimer AKD, and chitosan is 5:8:1; the molar ratio of heptafluorobutyric acid to dehydrating agent EDC·HCl is 1:3.

[0081] Comparative preparation example 3

[0082] Preparation of chitosan SK-C3 treated with heptafluorobutyric acid:

[0083] An appropriate amount of chitosan and heptafluorobutyric acid were dissolved in the organic solvent dimethyl sulfoxide, with a solid content of 20 wt%. Dehydrating agent EDC·HCl was added, and the mixture was reacted at 40°C in the dark for 20 h. After centrifugation and filtration, the mixture was washed three times with anhydrous ethanol and dried under vacuum at 85°C for 3 h to obtain heptafluorobutyric acid modified chitosan.

[0084] The molar ratio of heptafluorobutyric acid to chitosan is 10:1; the molar ratio of heptafluorobutyric acid to dehydrating agent EDC·HCl is 1:3.

[0085] Comparative preparation example 4

[0086] Preparation of chitosan SK-C4 modified with alkyl ketene dimer AKD:

[0087] An appropriate amount of chitosan and alkyl ketene dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 6 h, centrifuged and filtered, washed three times with anhydrous ethanol, and dried under vacuum at 85 °C for 3 h to obtain chitosan modified with alkyl ketene dimer AKD.

[0088] The molar ratio of alkyl ketene dimer AKD to chitosan is 10:1.

[0089] Preparation of cyclodextrin with hydrophobic modification

[0090] Preparation Example 1'

[0091] Preparation of hydrophobically modified cyclodextrin SH1:

[0092] Cyclodextrin and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 8 h, centrifuged and filtered, washed three times with anhydrous ethanol, and dried under vacuum at 85 °C for 3 h to obtain hydrophobically modified cyclodextrin.

[0093] The molar ratio of alkyl ketene dimer AKD to cyclodextrin is 8:1.

[0094] Preparation Example 2'

[0095] Preparation of cyclodextrin SH2 by hydrophobic modification:

[0096] Cyclodextrin and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 8 h, centrifuged and filtered, washed three times with anhydrous ethanol, and dried under vacuum at 85 °C for 3 h to obtain hydrophobically modified cyclodextrin.

[0097] The molar ratio of alkyl ketene dimer AKD to cyclodextrin is 10:1.

[0098] Comparative preparation example 1'

[0099] Preparation of hydrophobically modified cyclodextrin SH-C1:

[0100] Cyclodextrin and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 80 °C for 8 h, centrifuged and filtered, washed three times with anhydrous ethanol, and dried under vacuum at 85 °C for 3 h to obtain hydrophobically modified cyclodextrin.

[0101] The molar ratio of alkyl ketene dimer AKD to cyclodextrin is 6:1.

[0102] Example 1

[0103] The preparation of a waterproof pulp molding material includes the following steps:

[0104] S1. Weigh the raw materials according to the following components and their mass fractions:

[0105] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0106] 10 parts of chitosan SK1 treated with hydrophobic modification

[0107] Hydrophobic modification treatment of cyclodextrin SH1 (5 parts)

[0108] Alkyl ketene dimer AKD 3 parts

[0109] 0.5 parts of cationic polyacrylamide;

[0110] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK1, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0111] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0112] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0113] Example 2

[0114] The preparation of a waterproof pulp molding material includes the following steps:

[0115] S1. Weigh the raw materials according to the following components and their mass fractions:

[0116] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0117] 10 parts of chitosan SK2 treated with hydrophobic modification

[0118] Hydrophobic modification treatment of cyclodextrin SH1 (5 parts)

[0119] Alkyl ketene dimer AKD 3 parts

[0120] 0.5 parts of cationic polyacrylamide;

[0121] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK2, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0122] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0123] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0124] Example 3

[0125] The preparation of a waterproof pulp molding material includes the following steps:

[0126] S1. Weigh the raw materials according to the following components and their mass fractions:

[0127] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0128] 10 parts of chitosan SK3 with hydrophobic modification treatment

[0129] Hydrophobic modification treatment of cyclodextrin SH1 (5 parts)

[0130] Alkyl ketene dimer AKD 3 parts

[0131] 0.5 parts of cationic polyacrylamide;

[0132] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK3, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0133] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0134] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0135] Example 4

[0136] The preparation of a waterproof pulp molding material includes the following steps:

[0137] S1. Weigh the raw materials according to the following components and their mass fractions:

[0138] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0139] 10 parts of hydrophobically modified chitosan SK4

[0140] Hydrophobic modification treatment of cyclodextrin SH1 (5 parts)

[0141] Alkyl ketene dimer AKD 3 parts

[0142] 0.5 parts of cationic polyacrylamide;

[0143] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK4, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0144] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0145] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0146] Example 5

[0147] The preparation of a waterproof pulp molding material includes the following steps:

[0148] S1. Weigh the raw materials according to the following components and their mass fractions:

[0149] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0150] 10 parts of chitosan SK2 treated with hydrophobic modification

[0151] Hydrophobic modification treatment of cyclodextrin SH2 (5 parts)

[0152] Alkyl ketene dimer AKD 3 parts

[0153] 0.5 parts of cationic polyacrylamide;

[0154] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK2, the hydrophobically modified cyclodextrin SH2, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0155] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0156] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0157] Example 6

[0158] The preparation of a waterproof pulp molding material includes the following steps:

[0159] S1. Weigh the raw materials according to the following components and their mass fractions:

[0160] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0161] 15 parts of chitosan SK2 treated with hydrophobic modification

[0162] Hydrophobic modification treatment of cyclodextrin SH1 (5 parts)

[0163] Alkyl ketene dimer AKD 3 parts

[0164] 0.5 parts of cationic polyacrylamide;

[0165] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK2, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0166] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0167] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0168] Example 7

[0169] The preparation of a waterproof pulp molding material includes the following steps:

[0170] S1. Weigh the raw materials according to the following components and their mass fractions:

[0171] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0172] 15 parts of chitosan SK2 treated with hydrophobic modification

[0173] Hydrophobic modification treatment of cyclodextrin SH1 (3 parts)

[0174] Alkyl ketene dimer AKD 3 parts

[0175] 0.5 parts of cationic polyacrylamide;

[0176] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK2, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0177] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0178] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0179] Comparative Example 1

[0180] The preparation of a waterproof pulp molding material includes the following steps:

[0181] S1. Weigh the raw materials according to the following components and their mass fractions:

[0182] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0183] 10 parts of chitosan SK2 treated with hydrophobic modification

[0184] Hydrophobic modification treatment of cyclodextrin SH1 (10 parts)

[0185] Alkyl ketene dimer AKD 3 parts

[0186] 0.5 parts of cationic polyacrylamide;

[0187] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK2, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0188] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0189] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0190] Comparative Example 2

[0191] The preparation of a waterproof pulp molding material includes the following steps:

[0192] S1. Weigh the raw materials according to the following components and their mass fractions:

[0193] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0194] 15 parts of chitosan SK2 treated with hydrophobic modification

[0195] Hydrophobic modification of cyclodextrin SH1 2.5 parts

[0196] Alkyl ketene dimer AKD 3 parts

[0197] 0.5 parts of cationic polyacrylamide;

[0198] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK2, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0199] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0200] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0201] Comparative Example 3

[0202] The preparation of a waterproof pulp molding material includes the following steps:

[0203] S1. Weigh the raw materials according to the following components and their mass fractions:

[0204] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0205] 10 parts of hydrophobically modified chitosan SK-C1

[0206] Hydrophobic modification treatment of cyclodextrin SH1 (5 parts)

[0207] Alkyl ketene dimer AKD 3 parts

[0208] 0.5 parts of cationic polyacrylamide;

[0209] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK-C1, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0210] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0211] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0212] Comparative Example 4

[0213] The preparation of a waterproof pulp molding material includes the following steps:

[0214] S1. Weigh the raw materials according to the following components and their mass fractions:

[0215] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0216] 10 parts of hydrophobically modified chitosan SK-C2

[0217] Hydrophobic modification treatment of cyclodextrin SH1 (5 parts)

[0218] Alkyl ketene dimer AKD 3 parts

[0219] 0.5 parts of cationic polyacrylamide;

[0220] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK-C2, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0221] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0222] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0223] Comparative Example 5

[0224] The preparation of a waterproof pulp molding material includes the following steps:

[0225] S1. Weigh the raw materials according to the following components and their mass fractions:

[0226] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0227] 10 parts of hydrophobically modified chitosan SK-C3

[0228] Hydrophobic modification treatment of cyclodextrin SH1 (5 parts)

[0229] Alkyl ketene dimer AKD 3 parts

[0230] 0.5 parts of cationic polyacrylamide;

[0231] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK-C3, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0232] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0233] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0234] Comparative Example 6

[0235] The preparation of a waterproof pulp molding material includes the following steps:

[0236] S1. Weigh the raw materials according to the following components and their mass fractions:

[0237] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0238] 10 parts of hydrophobically modified chitosan SK-C4

[0239] Hydrophobic modification treatment of cyclodextrin SH1 (5 parts)

[0240] Alkyl ketene dimer AKD 3 parts

[0241] 0.5 parts of cationic polyacrylamide;

[0242] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK-C4, the hydrophobically modified cyclodextrin SH1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0243] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0244] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0245] Comparative Example 7

[0246] The preparation of a waterproof pulp molding material includes the following steps:

[0247] S1. Weigh the raw materials according to the following components and their mass fractions:

[0248] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0249] 10 parts of chitosan SK2 treated with hydrophobic modification

[0250] Hydrophobic modification treatment of cyclodextrin SH-C1 (5 parts)

[0251] Alkyl ketene dimer AKD 3 parts

[0252] 0.5 parts of cationic polyacrylamide;

[0253] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, the hydrophobically modified chitosan SK2, the hydrophobically modified cyclodextrin SH-C1, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0254] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0255] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0256] Comparative Example 8

[0257] The preparation of a waterproof pulp molding material includes the following steps:

[0258] S1. Weigh the raw materials according to the following components and their mass fractions:

[0259] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0260] 15 parts of chitosan SK2 treated with hydrophobic modification

[0261] Alkyl ketene dimer AKD 3 parts

[0262] 0.5 parts of cationic polyacrylamide;

[0263] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5 wt%. Then, the hydrophobically modified chitosan SK2, sizing agent and retention aid are added in sequence by internal sizing to obtain mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0264] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0265] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0266] Comparative Example 9

[0267] The preparation of a waterproof pulp molding material includes the following steps:

[0268] S1. Weigh the raw materials according to the following components and their mass fractions:

[0269] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0270] Hydrophobic modification treatment of cyclodextrin SH1 (15 parts)

[0271] Alkyl ketene dimer AKD 3 parts

[0272] 0.5 parts of cationic polyacrylamide;

[0273] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5wt%. Then, hydrophobically modified cyclodextrin SH1, sizing agent and retention aid are added in sequence by internal sizing to obtain mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0274] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0275] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0276] Comparative Example 10

[0277] The preparation of a waterproof pulp molding material includes the following steps:

[0278] S1. Weigh the raw materials according to the following components and their mass fractions:

[0279] Bamboo-wood blended pulp (a mixture of 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp) 80 parts

[0280] 10 parts chitosan

[0281] 5 parts of cyclodextrin

[0282] Alkyl ketene dimer AKD 3 parts

[0283] 0.5 parts of cationic polyacrylamide;

[0284] S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for 20 minutes, and tap water is added to dilute it to a pulp concentration of 5 wt%. Then, chitosan, cyclodextrin, sizing agent and retention aid are added in sequence by internal sizing to obtain mixed pulp. Each component is mixed for 30 minutes after being added before adding the next component.

[0285] S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5 min, and dry at 120℃ for 30 min to obtain semi-finished pulp molding material;

[0286] S4: Vacuum dewater the obtained semi-finished pulp molding material for 5 minutes to obtain the pulp molding material.

[0287] Sample preparation and performance testing:

[0288] The pulp molding materials of each embodiment and comparative example were placed in a constant temperature and humidity test chamber and treated at a temperature of (23±2)℃ and a relative humidity of (50±10)% for 24 h before their waterproof performance was tested.

[0289] The waterproof performance test method is as follows:

[0290] Cobb 60 value determination: The water absorption of molded pulp samples was determined using a Cobb absorbency tester according to GB / T 1540—2002. Cobb 60 (g / m³) was measured. 2 The Cobb value refers to the water absorption test time of 60 s. Five sheets were tested for each sample and the average value was taken.

[0291] Static water contact angle test: Cut 10 mm × 15 mm flat pulp molded samples, fix them to glass slides with double-sided tape, and use a contact angle meter to measure the wetting performance of deionized water on the surface of the pulp molded sample. Five test points are selected on each sample, and the average value is taken.

[0292] Hot water permeability test: According to GB / T 36787—2018, an appropriate amount of hot water at (95±5)℃ is dripped into the pulp molding sample, left to stand for 30 minutes, and observed whether there is any leakage of hot water.

[0293] The test results are shown in Table 1 below:

[0294] Table 1

[0295]

[0296] Comparing Examples 1-7 and Comparative Examples 1-10 in Table 1, it can be seen that the present invention, by adding hydrophobically modified chitosan and hydrophobically modified cyclodextrin to the pulp molding material through in-sizing, and by using heptafluorobutyric acid and AKD to hydrophobically modify chitosan and AKD to hydrophobically modify cyclodextrin, results in a final pulp molding material with good waterproof performance, Cobb60 < 8 g / m³. 2 The static water contact angle is >125°. After standing in hot water for 30 minutes, there is no seepage, leakage, or deformation on the back of the sample.

[0297] Comparing Examples 1-7 with Comparative Examples 1-2 in Table 1, it can be seen that when the compound ratio of hydrophobically modified chitosan and hydrophobically modified cyclodextrin in the pulp molding material is not within the range specified in this invention, all waterproof properties show a certain degree of decline.

[0298] Comparing Examples 1-7 with Comparative Examples 3-4 in Table 1, it can be seen that when preparing hydrophobically modified chitosan and hydrophobically modified cyclodextrin, if the molar ratio of heptafluorobutyric acid, AKD to chitosan, or AKD to cyclodextrin is not within the range defined by this invention, the various waterproof properties of the pulp molding material are relatively poor. This may be due to the different degrees of modification of the amino and hydroxyl groups on the surface of chitosan by heptafluorobutyric acid and AKD, or the different degrees of modification of the hydroxyl groups on the surface of cyclodextrin by AKD.

[0299] Comparing Example 7 with Comparative Examples 5-6 in Table 1, it can be seen that when only heptafluorobutyric acid or AKD is used for hydrophobic modification of chitosan during preparation, the waterproof performance of the pulp molding material is poor. This is because chitosan has hydroxyl and amino groups on its surface. Heptafluorobutyric acid improves the waterproof performance by modifying the amino groups with fluorine segments on the surface, while AKD modifies the hydroxyl groups, reducing the residual hydrophilic groups on the surface. Modification of only hydroxyl or amino groups cannot effectively improve the waterproof performance.

[0300] Comparing Examples 1-7 and Comparative Examples 8-10 in Table 1, it can be seen that the addition of hydrophobically modified chitosan and hydrophobically modified cyclodextrin to the pulp molding material produced a synergistic effect, which jointly improved the waterproof performance of the pulp molding material. However, the addition of chitosan and cyclodextrin without any hydrophobic treatment resulted in the worst waterproof performance.

[0301] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and not to limit them. Although the embodiments of the present invention have been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the embodiments of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A waterproof pulp molding material, characterized in that, Includes the following components and their mass fractions: 60-80 parts of bamboo and wood mixed pulp 10-15 parts of chitosan with hydrophobic modification 3-10 parts of hydrophobically modified cyclodextrin 1-3 parts of sizing agent Retention aid 0.1-0.5 parts; The mass ratio of the hydrophobically modified chitosan to the hydrophobically modified cyclodextrin is (2-5):1; The hydrophobically modified chitosan is chitosan co-modified with heptafluorobutyric acid and alkyl ketene dimer AKD; wherein the molar ratio of heptafluorobutyric acid, alkyl ketene dimer AKD and chitosan is (3-5):(5-7):

1. The hydrophobically modified cyclodextrin is cyclodextrin modified with alkyl ketene dimer AKD; wherein the molar ratio of alkyl ketene dimer AKD to cyclodextrin is (8-10):

1.

2. The waterproof pulp molding material according to claim 1, characterized in that, The bamboo-wood mixed pulp is obtained by mixing 70wt% bamboo chemical pulp and 30wt% coniferous wood chemical pulp; The sizing agent is selected from one or more of anionic dispersed rosin gum, cationic dispersed rosin gum, and alkyl ketene dimer AKD; The retention aid is selected from one or more of cationic polyacrylamide, anionic polyacrylamide, amphoteric polyacrylamide, and polyethyleneimine.

3. The waterproof pulp molding material according to claim 1, characterized in that, The specific preparation method of the hydrophobically modified chitosan is as follows: (1) Dissolve an appropriate amount of chitosan and heptafluorobutyric acid in the organic solvent dimethyl sulfoxide with a solid content of 20wt%. Add dehydrating agent EDC·HCl and react at 40-60℃ in the dark for 15-30h. After centrifugation, filtration, alcohol washing and drying, heptafluorobutyric acid modified chitosan is obtained. (2) Heptafluorobutyric acid modified chitosan and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt% and reacted at 60-80℃ for 5-8 h. After centrifugation, filtration, alcohol washing and drying, hydrophobically modified chitosan was obtained. The molar ratio of heptafluorobutyric acid to dehydrating agent EDC·HCl was 1:

3.

4. The waterproof pulp molding material according to claim 1, characterized in that, The specific preparation method of the hydrophobically modified cyclodextrin is as follows: Cyclodextrin and alkyl ketone dimer AKD were dissolved in ethyl acetate with a solid content of 20 wt%. The mixture was reacted at 60-80℃ for 5-8 h. After centrifugation, filtration, alcohol washing, and drying, hydrophobically modified cyclodextrin was obtained.

5. A method for preparing a waterproof pulp molding material according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Weigh the raw materials according to the following proportions by weight: bamboo and wood mixed pulp, hydrophobically modified chitosan, hydrophobically modified cyclodextrin, sizing agent and retention aid; S2. The bamboo and wood mixed pulp is loosened in the pulp tank of the pulping machine for a period of time, and then tap water is added to dilute it to a certain pulp concentration. Then, the hydrophobically modified chitosan, the hydrophobically modified cyclodextrin, the sizing agent and the retention aid are added in sequence by internal sizing to obtain the mixed pulp. Each component is mixed for 15-30 minutes after being added before adding the next component. S3. Transfer the above mixed pulp to a mold for molding, pressurize at 1000 kPa for 5-10 min, and dry at 100-120℃ for 30 min to obtain semi-finished pulp molding material; S4: Vacuum dewater the obtained semi-finished pulp molding material for 5-8 minutes to obtain the pulp molding material.

6. The method for preparing the waterproof pulp molding material according to claim 5, characterized in that, In step S2, the disintegration time is 5-20 min, and the pulp concentration after dilution is 5wt%-10wt%.

7. The application of a waterproof pulp molding material according to any one of claims 1-4 or a waterproof pulp molding material obtained by the preparation method according to any one of claims 5-6 in the field of waterproof packaging.

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