Preparation process of bombarding kraft paper
Through the preparation process of kneaded kraft paper, free radical polymerization modified silica and polyethyleneimine are used to form an electrostatic crosslinking structure, which solves the problem of low wet strength in traditional kraft paper in the state of prone to cracking and wet under heavy objects, and significantly improves the durability and wet strength of kraft paper.
Patent Information
- Application Number
- CN202510091797.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-21
- Publication Date
- 2025-03-28
AI Technical Summary
Traditional kraft paper is prone to rupture when it bears heavy objects, and has a low wet strength retention rate in a wet state, which affects its performance.
A preparation process of kneading kraft paper, including beating, scribing, coating and krafting, is adopted to form an epoxy polymer by radical polymerization, and co-modifying polyethyleneimine with other epoxy-containing substances to obtain additives with electrostatic crosslinking and amino and silicon elements, to enhance the mechanical properties and wet strength of kraft paper.
It significantly improves the durability, mechanical properties, wear resistance, wetting and chemical stability of kraft paper, and enhances its performance in humid environments.
Smart Images
Figure BDA0005251768040000081 
Figure BDA0005251768040000091
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of creped kraft paper, in particular to a preparation process of creped kraft paper. Background Art
[0002] With growing environmental awareness and increasing demands for paper quality, kraft paper, as an environmentally friendly, strong, and versatile packaging paper, particularly kraft paper bags, has garnered increasing attention in recent years. However, traditional kraft paper production processes are struggling to meet market demand for high-quality, diverse kraft paper products.
[0003] Kraft paper produced using conventional manufacturing processes for packaging has a certain upper limit to its burst strength. When used to support heavy items, the paper easily breaks, which not only affects the packaging quality but also significantly reduces the consumer experience. Furthermore, when wet, traditional kraft paper easily breaks hydrogen bonds between fibers, resulting in low wet strength retention. This compromises its performance in humid environments.
[0004] In summary, it is of great significance to prepare a rubbed kraft paper. Summary of the Invention
[0005] The object of the present invention is to provide a process for preparing creped kraft paper to solve the problems raised in the above background technology.
[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:
[0007] A process for preparing creped kraft paper comprises the following steps:
[0008] Step 1: adding softwood kraft bleached chemical pulp, hardwood kraft bleached chemical pulp, and coffee grounds into deionized water for crushing and beating, then adding additives for papermaking, coating with coating latex, and drying to obtain pretreated kraft paper;
[0009] Step 2: Soak the pretreated kraft paper in deionized water with softener added, wash with water for 1 to 2 hours, dry, add special auxiliary materials to the machine for the first rubbing, dry, add special auxiliary materials to the machine for the second rubbing, roll, inspect and package to obtain the rubbing kraft paper.
[0010] More optimally, the creped kraft paper comprises the following raw materials in parts by weight: 42-48 parts of softwood kraft bleached chemical pulp, 35-40 parts of hardwood kraft bleached chemical pulp, 2-5 parts of coffee grounds, 2-5 parts of additives, 30-35 parts of coating latex, and 2-3 parts of softener.
[0011] In a further embodiment, the coating latex is a propionate.
[0012] More optimally, in step 1, the specific process of beating is: after the crushing treatment, the beating concentration is set to 3.0-3.5%, and the beating degree is set to 15°SR-20°SR for beating.
[0013] More optimally, in step 1, the specific process of the papermaking treatment is: after beating, adding additives and conducting papermaking treatment at a papermaking speed of 70 to 80 m / min.
[0014] More optimally, in step 1, the specific process of coating is: after papermaking, setting the coating concentration to 25-30%, and applying the coating latex at a speed of 80-100 m / min for coating.
[0015] More optimally, in step 2, the softener comprises polyacrylamide and quaternary ammonium salt in a mass ratio of 1-1.5:0.5-0.8.
[0016] More optimally, the quaternary ammonium salt includes one or more of polyquaternium-10, polyquaternium-7, polyquaternium-11, and polyquaternium-6.
[0017] In a further embodiment, the quaternary ammonium salt is polyquaternium-10.
[0018] In a further embodiment, the molecular weight of polyquaternium-10 is 5000.
[0019] More optimally, in step 2, the specially prepared auxiliary materials include one or more of rubber balls, iron balls, stone balls, and sand bags.
[0020] More optimally, the preparation process of the additive is:
[0021] Step 1: Preparation of modified silica: (1) adding aminopolyethylene glycol epoxy group and 3-(2,3-epoxypropoxy)propyltrimethoxysilane to a 45-55 wt% methanol solution, reacting at 45-55° C. for 2-3 hours, purifying and drying to obtain a modified silane coupling agent; (2) adding the modified silane coupling agent and nano-silica to a 75-85 wt% ethanol aqueous solution, reacting at 50-80° C. for 8-10 hours, cooling and centrifuging to obtain modified silica;
[0022] Step 2: Add acrylamide, acrylic acid, 1,4-butanediol diacrylate, N,N'-methylenebisacrylamide, isooctyl acrylate, ammonium persulfate, sodium dodecylbenzenesulfonate, and polyoxyethylene octylphenyl ether to deionized water, adjust the pH to 6.0-7.5, react at 85-95° C. for 1-2 hours, and then adjust the pH to 6.9-7.1 to obtain polymer A; react dicyclohexylcarbodiimide, polymer A, and modified silica at 100-130° C. for 22-24 hours, and cool to obtain polymer B;
[0023] Step 3: Add polyethyleneimine, 2,3-epoxypropyltrimethylammonium chloride, polymer B, and 3-(2,3-epoxypropyloxy)propyltrimethoxysilane to a 45-55 wt% methanol solution, then add 8-12 wt% potassium hydroxide solution to adjust the pH to 7.8-8.3, react at 40-60°C for 2-3 hours, and adjust the pH to 4.0-4.5 to obtain an additive.
[0024] In a further embodiment, the molecular weight of polyethyleneimine is 5000; the molecular weight of aminopolyethylene glycol epoxy is 200.
[0025] In a further embodiment, the particle size of the nano-silica is 10 to 30 nm.
[0026] In the scheme, free radical polymerization and modified silica are used to synthesize modified polymers with epoxy groups, and then polyethyleneimine is modified together with other substances with epoxy groups to synthesize additives. The additives have strong cationic properties and can produce cross-linking with the fiber surface through electrostatic effects. While having softness, it can also increase mechanical properties, wear resistance, wettability, and chemical stability, thereby improving the durability of kraft paper and further improving the quality of creped kraft paper.
[0027] Acrylic acid and its derivatives have carbon-carbon double bonds, which can generate free radical copolymerization under the conditions of an initiator, introducing more flexible groups such as ester groups and creating cross-linked structures. This enhances the mechanical properties of kraft paper while maintaining its flexibility. However, these flexible groups are easily affected by acids and bases and have poor chemical stability. Therefore, this solution introduces modified inorganic fillers to enhance chemical stability while further improving the wear resistance and mechanical properties of kraft paper, further enhancing its durability.
[0028] Among them, in order to further enhance the wet strength of kraft paper, polyethyleneimine grafted silane coupling agent, quaternary ammonium salt, the above-mentioned polymer with epoxy group, and multiple amino groups are introduced to further improve the softness and wet strength of kraft paper, and synthesize kraft paper with wet strength, high temperature resistance, wear resistance, tear resistance and high strength.
[0029] In a further solution, in order to further enhance the softness, a softener is added to the solution, which works together with the additives to improve the feel of the kraft paper and facilitate subsequent rubbing operations.
[0030] More optimally, by weight, 2 to 3 parts of aminopolyethylene glycol epoxy, 2 to 4 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and 1 to 2 parts of nano-silica;
[0031] The polymer A comprises the following components: by mass, 2 to 3 parts of acrylamide, 2 to 3 parts of acrylic acid, 50 to 60 parts of deionized water, 5 to 7 parts of 1,4-butanediol diacrylate, 4 to 6 parts of N,N'-methylenebisacrylamide, 6 to 9 parts of isooctyl acrylate, 0.5 to 1 part of ammonium persulfate, 1 to 2 parts of sodium dodecylbenzenesulfonate, and 1 to 2 parts of polyoxyethylene octylphenyl ether;
[0032] The polymer B comprises the following components: 0.2 to 0.4 parts by mass of dicyclohexylcarbodiimide, 6 to 9 parts of polymer A, and 1 to 3 parts of modified silicon dioxide;
[0033] The additive comprises the following components: by mass, 6 to 9 parts of polyethyleneimine, 0.1 to 0.2 parts of 2,3-epoxypropyltrimethylammonium chloride, 0.05 to 0.1 parts of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane, 5 to 8 parts of polymer B, and 50 to 60 parts of 45 to 55 wt% methanol solution.
[0034] Compared with the prior art, the present invention has the following beneficial effects:
[0035] 1. In this scheme, silica is modified by free radical polymerization to form an epoxy polymer, which is then modified with other epoxy-containing substances to form polyethyleneimine to obtain an additive that can electrostatically cross-link with the fiber. On the basis of softness, amino groups, silicon elements, and cross-linking structures are introduced to further enhance the mechanical properties, softness, wear resistance, wettability and chemical stability, thereby improving the durability and quality of kraft paper. Subsequently, a softener is added during washing to synergistically improve the softness.
[0036] 2. The solution uses a secondary kneading operation method and adds special auxiliary materials into the machine during the kneading operation to synergistically increase the effect, speed and feel of kneading. DETAILED DESCRIPTION
[0037] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.
[0038] It should be noted that the following parts are by mass, and all raw materials involved in the present invention are purchased from manufacturers without any special restrictions. Examples include: in the following examples, the molecular weight of aminopolyethylene glycol epoxy is 200, and the product number is P002024; the particle size of nanosilica is 20 nm, and the product number is AM-SiO2-021-1; the molecular weight of polyethyleneimine is 5000, and the product number is 294321; the model of polyoxyethylene octylphenyl ether is OP-9; the product number of softwood kraft bleached chemical pulp is Y00011; and the product number of hardwood kraft bleached chemical pulp is 001.
[0039] Example 1: A process for preparing creped kraft paper, comprising the following steps:
[0040] Step 1: (1) adding 2.5 parts of aminopolyethylene glycol epoxy and 3 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane to a 50 wt% methanol solution, reacting at 50°C for 2.5 hours, purifying and drying to obtain a modified silane coupling agent; adding the modified silane coupling agent and 1.5 parts of nano-silica to an 80 wt% ethanol aqueous solution, reacting at 65°C for 9 hours, cooling and centrifuging to obtain modified silica; (2) adding 2.5 parts of acrylamide, 2.5 parts of acrylic acid, 6 parts of 1,4-butanediol diacrylate, 5 parts of N,N'-methylenebisacrylamide, 7.5 parts of isooctyl acrylate, 0.8 parts of ammonium persulfate, 1.5 parts of sodium dodecylbenzenesulfonate, and 1.5 parts of polyoxyethylene octylphenyl ether; Add to 55 parts of deionized water, adjust the pH to 6.8, react at 90°C for 1.5 hours, and then adjust the pH to 7.0 to obtain polymer A; react 0.3 parts of dicyclohexylcarbodiimide, 7.5 parts of polymer A, and 2 parts of modified silica at 115°C for 23 hours, cool, and obtain polymer B; (3) add 7.5 parts of polyethyleneimine, 0.15 parts of 2,3-epoxypropyltrimethylammonium chloride, 6.5 parts of polymer B, and 0.08 parts of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane to 55 parts of 50wt% methanol solution, then add 10wt% potassium hydroxide solution to adjust the pH to 8.0, react at 50°C for 2.5 hours, and adjust the pH to 4.2 to obtain an additive;
[0041] Step 2: adding 45 parts of softwood kraft bleached chemical pulp, 38 parts of hardwood kraft bleached chemical pulp, and 3.5 parts of coffee grounds to deionized water for disintegration treatment, setting the beating concentration to 3.2% and the beating degree to 18°SR for beating, then adding 3.5 parts of additives and performing papermaking treatment at a papermaking speed of 75 m / min, setting the coating concentration to 28%, applying 32 parts of coating latex at a speed of 90 m / min for coating, and drying to obtain pretreated kraft paper;
[0042] Step 3: Soak the pretreated kraft paper in deionized water with 2.5 parts of softener, the softener includes polyacrylamide and polyquaternium-10 in a mass ratio of 1.2:0.65, wash with water for 1.5 hours, dry, add special auxiliary materials to the machine for the first rubbing, the special auxiliary materials are rubber balls, dry, add special auxiliary materials to the machine for the second rubbing, roll, inspect and package to obtain rubbing kraft paper.
[0043] Example 2: A process for preparing creped kraft paper, comprising the following steps:
[0044] Step 1: (1) adding 2.5 parts of aminopolyethylene glycol epoxy and 3 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane to a 50 wt% methanol solution, reacting at 50°C for 2.5 hours, purifying and drying to obtain a modified silane coupling agent; adding the modified silane coupling agent and 1.5 parts of nano-silica to an 80 wt% ethanol aqueous solution, reacting at 65°C for 9 hours, cooling and centrifuging to obtain modified silica; (2) adding 2.5 parts of acrylamide, 2.5 parts of acrylic acid, 6 parts of 1,4-butanediol diacrylate, 5 parts of N,N'-methylenebisacrylamide, 7.5 parts of isooctyl acrylate, 0.8 parts of ammonium persulfate, 1.5 parts of sodium dodecylbenzenesulfonate, and 1.5 parts of polyoxyethylene octylphenyl ether; Add to 55 parts of deionized water, adjust the pH to 6.0, react at 90°C for 1.5 hours, and then adjust the pH to 6.9 to obtain polymer A; react 0.3 parts of dicyclohexylcarbodiimide, 7.5 parts of polymer A, and 2 parts of modified silica at 115°C for 23 hours, cool, and obtain polymer B; (3) add 7.5 parts of polyethyleneimine, 0.15 parts of 2,3-epoxypropyltrimethylammonium chloride, 6.5 parts of polymer B, and 0.08 parts of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane to 55 parts of 50wt% methanol solution, then add 10wt% potassium hydroxide solution to adjust the pH to 7.8, react at 50°C for 2.5 hours, and adjust the pH to 4.0 to obtain an additive;
[0045] Step 2: adding 45 parts of softwood kraft bleached chemical pulp, 38 parts of hardwood kraft bleached chemical pulp, and 2 parts of coffee grounds to deionized water for disintegration treatment, setting the beating concentration to 3.2% and the beating degree to 18°SR for beating, then adding 2 parts of additives and performing papermaking treatment at a papermaking speed of 75 m / min, setting the coating concentration to 28%, applying 32 parts of coating latex at a speed of 90 m / min for coating, and drying to obtain pretreated kraft paper;
[0046] Step 3: Soak the pretreated kraft paper in deionized water with 2 parts of softener added, the softener includes polyacrylamide and polyquaternium-10 in a mass ratio of 1:0.5, wash with water for 1 hour, dry, add special auxiliary materials to the machine for the first rubbing, the special auxiliary materials are rubber balls, dry, add special auxiliary materials to the machine for the second rubbing, roll, inspect and package to obtain rubbing kraft paper.
[0047] Example 3: A process for preparing creped kraft paper, comprising the following steps:
[0048] Step 1: (1) adding 2.5 parts of aminopolyethylene glycol epoxy and 3 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane to a 50 wt% methanol solution, reacting at 50°C for 2.5 hours, purifying and drying to obtain a modified silane coupling agent; adding the modified silane coupling agent and 1.5 parts of nano-silica to an 80 wt% ethanol aqueous solution, reacting at 65°C for 9 hours, cooling and centrifuging to obtain modified silica; (2) adding 2.5 parts of acrylamide, 2.5 parts of acrylic acid, 6 parts of 1,4-butanediol diacrylate, 5 parts of N,N'-methylenebisacrylamide, 7.5 parts of isooctyl acrylate, 0.8 parts of ammonium persulfate, 1.5 parts of sodium dodecylbenzenesulfonate, and 1.5 parts of polyoxyethylene octylphenyl ether; Add to 55 parts of deionized water, adjust the pH to 7.5, react at 90°C for 1.5 hours, and then adjust the pH to 7.1 to obtain polymer A; react 0.3 parts of dicyclohexylcarbodiimide, 7.5 parts of polymer A, and 2 parts of modified silica at 115°C for 23 hours, cool, and obtain polymer B; (3) add 7.5 parts of polyethyleneimine, 0.15 parts of 2,3-epoxypropyltrimethylammonium chloride, 6.5 parts of polymer B, and 0.08 parts of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane to 55 parts of 50wt% methanol solution, then add 10wt% potassium hydroxide solution to adjust the pH to 8.3, react at 50°C for 2.5 hours, and adjust the pH to 4.5 to obtain an additive;
[0049] Step 2: adding 45 parts of softwood kraft bleached chemical pulp, 38 parts of hardwood kraft bleached chemical pulp, and 5 parts of coffee grounds to deionized water for disintegration treatment, setting the beating concentration to 3.2% and the beating degree to 18°SR for beating, then adding 5 parts of additives and performing papermaking treatment at a papermaking speed of 75 m / min, setting the coating concentration to 28%, applying 32 parts of coating latex at a speed of 90 m / min for coating, and drying to obtain pretreated kraft paper;
[0050] Step 3: Soak the pretreated kraft paper in deionized water with 3 parts of softener added, the softener includes polyacrylamide and polyquaternium-10 with a mass ratio of 1.5:0.8, wash with water for 2 hours, dry, add special auxiliary materials to the machine for the first rubbing, the special auxiliary materials are rubber balls, dry, add special auxiliary materials to the machine for the second rubbing, roll, inspect and package to obtain rubbing kraft paper.
[0051] Comparative Example 1: Based on Example 1, modified silicon dioxide was not added, and the other processes remained unchanged, specifically:
[0052] Step 1: (1) 2.5 parts of acrylamide, 2.5 parts of acrylic acid, 6 parts of 1,4-butanediol diacrylate, 5 parts of N,N'-methylenebisacrylamide, 7.5 parts of isooctyl acrylate, 0.8 parts of ammonium persulfate, 1.5 parts of sodium dodecylbenzenesulfonate, and 1.5 parts of polyoxyethylene octylphenyl ether are added to 55 parts of deionized water, and the pH is adjusted to 6.8. The mixture is reacted at 90°C for 1.5 hours, and then the pH is adjusted to 7.0 to obtain polymer A; (2) 7.5 parts of polyethyleneimine, 0.15 parts of 2,3-epoxypropyltrimethylammonium chloride, 5.5 parts of polymer A, and 0.08 parts of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane are added to 55 parts of a 50 wt% methanol solution, and then a 10 wt% potassium hydroxide solution is added to adjust the pH to 8.0. The mixture is reacted at 50°C for 2.5 hours, and the pH is adjusted to 4.2 to obtain an additive;
[0053] Step 2: adding 45 parts of softwood kraft bleached chemical pulp, 38 parts of hardwood kraft bleached chemical pulp, and 3.5 parts of coffee grounds to deionized water for disintegration treatment, setting the beating concentration to 3.2% and the beating degree to 18°SR for beating, then adding 3.5 parts of additives and performing papermaking treatment at a papermaking speed of 75 m / min, setting the coating concentration to 28%, applying 32 parts of coating latex at a speed of 90 m / min for coating, and drying to obtain pretreated kraft paper;
[0054] Step 3: Soak the pretreated kraft paper in deionized water with 2.5 parts of softener, the softener includes polyacrylamide and polyquaternium-10 in a mass ratio of 1.2:0.65, wash with water for 1.5 hours, dry, add special auxiliary materials to the machine for the first rubbing, the special auxiliary materials are rubber balls, dry, add special auxiliary materials to the machine for the second rubbing, roll, inspect and package to obtain rubbing kraft paper.
[0055] Comparative Example 2: Based on Example 1, polymer B replaces the additive, and the rest of the process remains unchanged, specifically:
[0056] Step 1: (1) adding 2.5 parts of aminopolyethylene glycol epoxy and 3 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane to a 50 wt% methanol solution, reacting at 50°C for 2.5 hours, purifying and drying to obtain a modified silane coupling agent; adding the modified silane coupling agent and 1.5 parts of nano-silica to an 80 wt% ethanol aqueous solution, reacting at 65°C for 9 hours, cooling and centrifuging to obtain modified silica; (2) adding 2.5 parts of acrylamide, 2.5 parts of acrylic acid, 6 parts of 1,4-butanediol, Glycol diacrylate, 5 parts of N,N'-methylenebisacrylamide, 7.5 parts of isooctyl acrylate, 0.8 parts of ammonium persulfate, 1.5 parts of sodium dodecylbenzenesulfonate, and 1.5 parts of polyoxyethylene octylphenyl ether were added to 55 parts of deionized water, and the pH was adjusted to 6.8. The mixture was reacted at 90°C for 1.5 hours, and then the pH was adjusted to 7.0 to obtain polymer A. 0.3 parts of dicyclohexylcarbodiimide, 7.5 parts of polymer A, and 2 parts of modified silica were reacted at 115°C for 23 hours, and then cooled to obtain an additive.
[0057] Step 2: adding 45 parts of softwood kraft bleached chemical pulp, 38 parts of hardwood kraft bleached chemical pulp, and 3.5 parts of coffee grounds to deionized water for disintegration treatment, setting the beating concentration to 3.2% and the beating degree to 18°SR for beating, then adding 3.5 parts of additives and performing papermaking treatment at a papermaking speed of 75 m / min, setting the coating concentration to 28%, applying 32 parts of coating latex at a speed of 90 m / min for coating, and drying to obtain pretreated kraft paper;
[0058] Step 3: Soak the pretreated kraft paper in deionized water with 2.5 parts of softener, the softener includes polyacrylamide and polyquaternium-10 in a mass ratio of 1.2:0.65, wash with water for 1.5 hours, dry, add special auxiliary materials to the machine for the first rubbing, the special auxiliary materials are rubber balls, dry, add special auxiliary materials to the machine for the second rubbing, roll, inspect and package to obtain rubbing kraft paper.
[0059] Comparative Example 3: Based on Example 1, the additive was changed to styrene-butadiene latex, and the other processes remained unchanged, specifically:
[0060] Step 1: 45 parts of softwood kraft bleached chemical pulp, 38 parts of hardwood kraft bleached chemical pulp, and 3.5 parts of coffee grounds are added to deionized water for crushing treatment, and the beating concentration is set to 3.2%, and the beating degree is set to 18°SR for beating, and then 3.5 parts of styrene-butadiene latex are added and papermaking treatment is carried out at a papermaking speed of 75 m / min, and the coating concentration is set to 28%, and 32 parts of the coating latex are applied at a speed of 90 m / min for coating, and dried to obtain pretreated kraft paper;
[0061] Step 2: Soak the pretreated kraft paper in deionized water, wash it for 1.5 hours, dry it, add special auxiliary materials into the machine for the first rubbing, the special auxiliary materials are rubber balls, dry it, add special auxiliary materials into the machine for the second rubbing, roll it up, inspect it, and package it to obtain the rubbing kraft paper.
[0062] Comparative Example 4: Based on Example 1, free radical copolymerization was not used, and the other processes remained unchanged, specifically:
[0063] Step 1: (1) adding 2.5 parts of aminopolyethylene glycol epoxy and 3 parts of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane to a 50 wt% methanol solution, reacting at 50°C for 2.5 hours, purifying and drying to obtain a modified silane coupling agent; adding the modified silane coupling agent and 1.5 parts of nano-silica to an 80 wt% ethanol aqueous solution, reacting at 65°C for 9 hours, cooling and centrifuging to obtain modified silica; (2) adding 5.5 parts of polyethyleneimine, 0.15 parts of 2,3-epoxypropyltrimethylammonium chloride, 1 part of modified silica, and 0.08 parts of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane to 55 parts of a 50 wt% methanol solution, then adding 10 wt% potassium hydroxide solution to adjust the pH to 8.0, reacting at 50°C for 2.5 hours, and adjusting the pH to 4.2 to obtain an additive;
[0064] Step 2: adding 45 parts of softwood kraft bleached chemical pulp, 38 parts of hardwood kraft bleached chemical pulp, and 3.5 parts of coffee grounds to deionized water for disintegration treatment, setting the beating concentration to 3.2% and the beating degree to 18°SR for beating, then adding 3.5 parts of additives and performing papermaking treatment at a papermaking speed of 75 m / min, setting the coating concentration to 28%, applying 32 parts of coating latex at a speed of 90 m / min for coating, and drying to obtain pretreated kraft paper;
[0065] Step 3: Soak the pretreated kraft paper in deionized water with 2.5 parts of softener, the softener includes polyacrylamide and polyquaternium-10 in a mass ratio of 1.2:0.65, wash with water for 1.5 hours, dry, add special auxiliary materials to the machine for the first rubbing, the special auxiliary materials are rubber balls, dry, add special auxiliary materials to the machine for the second rubbing, roll, inspect and package to obtain rubbing kraft paper.
[0066] Test experiment 1: The performance of the creped kraft paper prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested: (1) Mechanical properties test: The creped kraft paper prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested at 70 g / cm 2The samples were tested for burst resistance with reference to GB / T 22865-2008, and the results are shown in Table 1; (2) Wet strength test: The creped kraft paper prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested for its wet tensile index with reference to GB / T 24328.4-2020, and the results are shown in Table 1.
[0067]
[0068]
[0069] Table 1
[0070] Result analysis: According to the data analysis in Table 1, it can be seen that this scheme uses free radical copolymerization and introduces modified silica to form a cross-linked network structure, thereby enhancing the overall mechanical properties of the creped kraft paper; the scheme introduces coupling groups to form a three-dimensional network structure to further improve the wet strength and waterproof properties.
[0071] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.
Claims
1. A process for preparing creped kraft paper, characterized in that: The following steps are involved: Step 1: adding softwood kraft bleached chemical pulp, hardwood kraft bleached chemical pulp and coffee grounds into deionized water for crushing and pulping, then adding additives for papermaking, coating with coating latex, and drying to obtain pretreated kraft paper; Step 2: Soak the pretreated kraft paper in deionized water with softener added, wash for 1 to 2 hours, dry, add special auxiliary materials in the machine for the first rubbing, dry, add special auxiliary materials in the machine for the second rubbing, roll, inspect and package to obtain rubbing kraft paper.
2. The process for preparing creped kraft paper according to claim 1, characterized in that: The rubbed kraft paper comprises the following raw materials in parts by weight: 42-48 parts of softwood kraft bleached chemical pulp, 35-40 parts of hardwood kraft bleached chemical pulp, 2-5 parts of coffee grounds, 2-5 parts of additives, 30-35 parts of coating latex, and 2-3 parts of softener.
3. The process for preparing creped kraft paper according to claim 1, characterized in that: In step 1, the specific process of pulping is: after the crushing treatment, the pulping concentration is set to 3.0-3.5%, and the pulping degree is set to 15°SR-20°SR for pulping.
4. The process for preparing creped kraft paper according to claim 1, characterized in that: In step 1, the specific process of the papermaking treatment is: after pulping, additives are added and the papermaking treatment is carried out at a papermaking speed of 70 to 80 m / min.
5. The process for preparing creped kraft paper according to claim 1, characterized in that: In step 1, the specific process of coating is: after papermaking, setting the coating concentration to 25-30%, and applying the coating latex at a speed of 80-100 m / min for coating.
6. The process for preparing creped kraft paper according to claim 1, characterized in that: In step 2, the softener includes polyacrylamide and quaternary ammonium salt in a mass ratio of 1-1.5:0.5-0.
8.
7. The process for preparing creped kraft paper according to claim 6, characterized in that: The quaternary ammonium salt includes one or more of polyquaternium-10, polyquaternium-7, polyquaternium-11, and polyquaternium-6.
8. The process for preparing creped kraft paper according to claim 1, characterized in that: In step 2, the special auxiliary materials include one or more of rubber balls, iron balls, stone balls, and sand bags.
9. The process for preparing creped kraft paper according to claim 1, characterized in that: The preparation process of the additive is: Step 1: Preparation of modified silica: (1) adding aminopolyethylene glycol epoxy group and 3-(2,3-epoxypropoxy)propyltrimethoxysilane to a 45-55 wt % methanol solution, reacting at 45-55° C. for 2-3 hours, purifying and drying to obtain a modified silane coupling agent; (2) adding a modified silane coupling agent and nano-silica to a 75-85 wt % ethanol aqueous solution, reacting at 50-80° C. for 8-10 hours, cooling, and centrifuging to obtain modified silica; Step 2: Add acrylamide, acrylic acid, 1,4-butanediol diacrylate, N,N'-methylenebisacrylamide, isooctyl acrylate, ammonium persulfate, sodium dodecylbenzene sulfonate, and polyoxyethylene octylphenyl ether to deionized water, adjust the pH to 6.0-7.5, react at 85-95° C. for 1-2 hours, and then adjust the pH to 6.9-7.1 to obtain polymer A; react dicyclohexylcarbodiimide, polymer A, and modified silica at 100-130° C. for 22-24 hours, and cool to obtain polymer B; Step 3: Add polyethyleneimine, 2,3-epoxypropyltrimethylammonium chloride, polymer B, and 3-(2,3-epoxypropyloxy)propyltrimethoxysilane to a 45-55wt% methanol solution, then add 8-12wt% potassium hydroxide solution to adjust the pH to 7.8-8.3, react at 40-60°C for 2-3 hours, adjust the pH to 4.0-4.5, and obtain an additive.
10. The process for preparing creped kraft paper according to claim 9, characterized in that: The modified silicon dioxide comprises the following components: 2 to 3 parts by mass of aminopolyethylene glycol epoxy, 2 to 4 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and 1 to 2 parts of nano silicon dioxide; The polymer A comprises the following components: by mass, 2 to 3 parts of acrylamide, 2 to 3 parts of acrylic acid, 50 to 60 parts of deionized water, 5 to 7 parts of 1,4-butanediol diacrylate, 4 to 6 parts of N,N'-methylenebisacrylamide, 6 to 9 parts of isooctyl acrylate, 0.5 to 1 part of ammonium persulfate, 1 to 2 parts of sodium dodecylbenzene sulfonate, and 1 to 2 parts of polyoxyethylene octylphenyl ether; The polymer B comprises the following components: by mass, 0.2-0.4 parts of dicyclohexylcarbodiimide, 6-9 parts of polymer A, and 1-3 parts of modified silicon dioxide; The additive comprises the following components: by mass, 6-9 parts of polyethyleneimine, 0.1-0.2 parts of 2,3-epoxypropyltrimethylammonium chloride, 0.05-0.1 parts of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane, 5-8 parts of polymer B, and 50-60 parts of 45-55wt% methanol solution.