Production process of washable environment-friendly kitchen paper

Abstract

The application discloses a production process and product of washable and environment-friendly kitchen paper, and the process comprises the steps of slurry preparation, wet strength agent addition, sheet forming, TAD drying and post-treatment. The slurry is prepared by mixing 45% needle-leaf wood pulp fibers and broad-leaf wood pulp fibers and performing differential beating treatment; the wet strength agent is prepared by compounding polyamide epichlorohydrin resin and cationic starch, and is added in a specific order and proportion; after dehydration and forming in a TAD paper machine net part, the kitchen paper is dried by hot air penetration through a front drying cylinder and a main drying cylinder, the hot air speed of the main drying cylinder hood is 18-20 m / s; and the post-treatment adopts a composite process combining point sticking and line sticking. Through the cooperation of fiber ratio, wet strength agent compounding and TAD drying technology, the kitchen paper prepared by the process has a longitudinal wet tensile strength not lower than 300 mN, can withstand not less than 4 times of standard washing, has the properties of environmental protection and durability, and meets the washing and reuse requirements of the kitchen cleaning scene.

Description

Technical Field

[0001] This invention belongs to the field of papermaking technology, and in particular relates to a production process for washable and environmentally friendly kitchen paper. Background Technology

[0002] The current domestic kitchen paper market exhibits a coexistence of demand upgrading and product category gaps. The market size has grown rapidly, reaching 12 billion yuan in 2024, with household penetration increasing to 58%. However, environmentally friendly and reusable products account for less than 5%, indicating a supply shortage. Consumer pain points are concentrated on insufficient absorbency and waste from single disposal. Middle- and high-income groups are willing to pay a premium for environmentally friendly and durable products, with demand upgrading towards "high efficiency + sustainability." However, market competition is highly homogenized, with mainstream products relying on high-cost imported long fibers, and performance limited to basic absorbency, lacking differentiation. Technologically, TAD technology is applied in less than 10% of kitchen paper products, resulting in low bulk and poor wet strength, failing to meet reusability requirements. Core technologies face bottlenecks such as balancing long fiber ratio and strength, and the contradiction between wet strength agents and absorbency. Furthermore, there is a lack of a systematic TAD process parameter database, leading to low R&D efficiency. In contrast, European and American companies have achieved large-scale application of TAD technology, successfully balancing strength and absorbency through refined fiber separation and a low-dose, high-efficiency wet strength agent system. Their reusable products significantly outperform ordinary domestic products. Overall, the domestic market urgently needs breakthroughs in technology to fill the supply gap for environmentally friendly and durable kitchen paper. Summary of the Invention

[0003] To address the core contradiction in existing domestic kitchen paper technology—the reliance on outdated processes that rely on high-cost, high-proportion imported long fibers, making it difficult to balance the necessary "high wet strength" and "high absorbency" for reusability—this invention provides a production process for washable and environmentally friendly kitchen paper.

[0004] To achieve the above objectives, a first aspect of the present invention provides a production process for washable and environmentally friendly kitchen paper, comprising the following steps: Pulp preparation: Softwood pulp fibers and hardwood pulp fibers are mixed and pulped to obtain pulp, wherein softwood pulp fibers account for 45% of the total fiber mass; Addition of wet strength agent: Add polyamide epichlorohydrin resin and cationic starch to the slurry and mix until homogeneous; Papermaking: The pulp with added wet strength agent is fed to the wire section of the TAD paper machine and dewatered to form a wet paper web; TAD Drying: The wet paper web is sequentially passed through the front drying cylinder and the main drying cylinder of the TAD paper machine for hot air penetration drying. The hot air velocity of the main drying cylinder air hood system is 18-20 m / s. Post-processing: The dried paper web is sequentially calendered, laminated, and slit to obtain the washable and environmentally friendly kitchen paper.

[0005] Furthermore, in the pulp preparation step, the softwood pulp fiber is lightly pulped to control its freeness to 30-35°SR; the hardwood pulp fiber is moderately pulped to control its freeness to 25-30°SR.

[0006] Furthermore, the amount of polyamide epichlorohydrin resin added is 0.8%-1.2% of the oven-dry slurry mass; the amount of cationic starch added is 0.1% of the oven-dry slurry mass.

[0007] Furthermore, in the wet strength agent addition step, the polyamide epichlorohydrin resin is added in the slurry mixing tank and the mixing time with the slurry is not less than 15 minutes; the cationic starch is added before the headbox.

[0008] Furthermore, in the TAD drying step, the temperature of the pre-drying cylinder is 120-130℃, and the temperature of the main drying cylinder is 130-140℃.

[0009] Furthermore, in the copying process, the vacuum level of the mesh section is controlled between -0.06 MPa and -0.08 MPa.

[0010] Furthermore, the lamination process in the post-processing step adopts a combination of point bonding and line bonding.

[0011] Furthermore, the spacing between the dots is 5mm × 5mm, the width of the line is 2mm, and the composite pressure is controlled at 0.2-0.3MPa.

[0012] Secondly, the present invention also provides a washable and environmentally friendly kitchen paper, which is produced by any of the washing and environmentally friendly kitchen paper production processes described in any one of the claims.

[0013] Furthermore, its longitudinal wet tensile strength is not less than 300mN, and it can withstand no less than 4 standard water washing tests.

[0014] The beneficial technical effects of the present invention are at least as follows: This invention provides a production process for washable and environmentally friendly kitchen paper towels. One key benefit is that it significantly reduces raw material costs while achieving the crucial reusability of the product. Through innovative low-long-fiber ratio technology and a PAE-starch synergistic wet strength system, the proportion of imported long fibers is successfully reduced to 45%. While lowering pulp costs by 4.2%, the paper still maintains superior wet strength (longitudinal wet tensile strength ≥180mN) and washability (washable up to 4 times), overcoming the industry challenge of simultaneously achieving cost, strength, and durability. Secondly, the product produced by this process perfectly integrates the three core advantages of "highly efficient cleaning," "economical," and "environmentally friendly." Based on the optimized TAD process, the product boasts higher bulk and absorbency, significantly improving cleaning efficiency. Effective cost control allows the final selling price to be only about one-third of imported similar products, making it highly competitive in the market. Furthermore, each sheet can be reused multiple times, directly reducing daily consumption by more than 50%, significantly saving wood resources and reducing waste at the source, thus offering both outstanding consumer value and social and environmental benefits. Attached Figure Description

[0015] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0016] Figure 1 This is a flowchart of one of the production process steps for a washable and environmentally friendly kitchen paper product according to the present invention. Detailed Implementation

[0017] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0018] Example 1 refer to Figure 1 This invention provides an embodiment to address the core contradiction faced by existing domestic kitchen paper technology, which relies on outdated processes that rely on high-cost, high-proportion imported long fibers, making it difficult to balance the necessary "high wet strength" and "high absorbency" for reusability. While advanced processes and fiber ratio technologies such as TAD, which have been mastered abroad, are not yet available in China, this invention provides a production process for washable and environmentally friendly kitchen paper.

[0019] Example 1 A production process for washable and environmentally friendly kitchen paper towels is provided, including the following steps: Pulp preparation: Softwood pulp fibers and hardwood pulp fibers are mixed and pulped to obtain pulp, wherein softwood pulp fibers account for 45% of the total fiber mass; Addition of wet strength agent: Add polyamide epichlorohydrin resin and cationic starch to the slurry and mix until homogeneous; Papermaking: The pulp with added wet strength agent is fed to the wire section of the TAD paper machine and dewatered to form a wet paper web; TAD Drying: The wet paper web is sequentially passed through the front drying cylinder and the main drying cylinder of the TAD paper machine for hot air penetration drying. The hot air velocity of the main drying cylinder air hood system is 18-20 m / s. Post-processing: The dried paper web is sequentially calendered, laminated, and slit to obtain the washable and environmentally friendly kitchen paper.

[0020] Raw material preparation and slurry pretreatment: Fiber ratio: 45% imported softwood pulp (long fiber, average length 2.8-3.2mm) and 55% imported hardwood pulp (short fiber, average length 1.8-2.2mm) are mixed.

[0021] Long fiber pretreatment: Lightly beat the softwood pulp, control the beating degree to 30-35°SR, and use a fiber grading sieve to ensure that the retained fiber length is not less than 2.8mm.

[0022] Short fiber pretreatment: The hardwood pulp is moderately beaten, and the beating degree is controlled at 25-30°SR. The fiber specific surface area is increased to not less than 1.2 m² / g through a grinding process.

[0023] Based on the TAD production line, drying and wire section parameters are coordinated and controlled to optimize the paper structure. Specifically, this includes: Drying curve optimization: Setting the temperature of the pre-drying cylinder (small drying cylinder) to 120-130℃ to rapidly reduce the pulp moisture content from 40% to 25%, preventing premature fiber shrinkage; setting the temperature of the main drying cylinder to 130-140℃, while controlling the hot air velocity of the wet-end hood of the main drying cylinder to 18-20 m / s to penetrate the fiber layer and form a porous structure, ensuring a paper bulk of no less than 1.2 cm³ / g; controlling the dry hood temperature at 125-135℃ to slowly dry the paper web to a finished moisture content of 6%-8%, preventing fiber embrittlement. Wire section parameter control: Controlling the forming wire tension at 20-25 N / m (monitored in real-time by a tension sensor), and maintaining the wire section vacuum at -0.06 to -0.08 MPa to ensure uniform pulp adhesion. Simultaneously, controlling the inlet air humidity at 15-20% RH to prevent paper wrinkling. During the production process, key process parameters are recorded every hour, and a "TAD process parameter-product performance" correlation database is built for process optimization.

[0024] To impart excellent washability and durability to the product, the lamination and post-processing techniques were optimized. The lamination process employs a combination of spot and line bonding to laminate two or three layers of paper. The spot bonding spacing is 5mm x 5mm, the line bonding width is 2mm, and the lamination pressure is controlled at 0.2-0.3MPa (controlled in real-time by a pressure sensor). This process avoids the clogging of the liquid absorption channels caused by traditional full-width bonding. Water wash stability verification: To verify the product's reusability, a simulated household washing scenario (water temperature 25-30℃, detergent concentration 0.5%, stirring speed 100r / min) was conducted on the finished product for four cycles of washing. After each wash, the wet tensile strength (not less than 300mN for two-layer products) and dust loss rate (not higher than 0.5%) were tested according to relevant standards to ensure the product meets reusability requirements.

[0025] Furthermore, in the pulp preparation step, the softwood pulp fiber is lightly pulped to control its freeness to 30-35°SR; the hardwood pulp fiber is moderately pulped to control its freeness to 25-30°SR.

[0026] Addition of wet strength agent and preparation of slurry: Wet strength agent system: A synergistic system of PAE (polyamide epichlorohydrin resin) and cationic starch is adopted.

[0027] Addition ratio: PAE addition amount is 0.8%-1.2% of the oven-dry pulp weight, and cationic starch addition amount is 0.1%.

[0028] Addition process: A staged addition method is adopted. First, PAE is added to the mixing tank and mixed thoroughly with the slurry for at least 15 minutes; then, cationic starch is added before the headbox to avoid premature flocculation of the slurry. The precise and stable addition amount is ensured by an online concentration monitor (tested once per hour).

[0029] Furthermore, the amount of polyamide epichlorohydrin resin added is 0.8%-1.2% of the oven-dry slurry mass; the amount of cationic starch added is 0.1% of the oven-dry slurry mass.

[0030] Furthermore, in the wet strength agent addition step, the polyamide epichlorohydrin resin is added in the slurry mixing tank and the mixing time with the slurry is not less than 15 minutes; the cationic starch is added before the headbox.

[0031] Furthermore, in the TAD drying step, the temperature of the pre-drying cylinder is 120-130℃, and the temperature of the main drying cylinder is 130-140℃.

[0032] Wire forming: Control the wire tension at 20-25 N / m (monitored in real time by tension sensor), maintain the wire vacuum at -0.06 to -0.08 MPa, and control the air humidity at 15-20% RH to ensure uniform adhesion of the pulp and avoid paper wrinkling.

[0033] Drying curve: Front drying: The temperature of the front drying cylinder (small drying cylinder) is set to 120-130℃, so that the moisture content of the paper web drops rapidly from about 40% to 25%, avoiding fiber shrinkage.

[0034] Main drying: The temperature of the main drying cylinder is set to 130-140℃. The hot air velocity of the wet end hood of the main drying cylinder hood system is controlled at 18-20 m / s. The hot air penetration effect forms a porous structure in the fiber layer, so that the paper bulk reaches not less than 1.2cm³ / g.

[0035] Post-drying: The temperature of the drying hood system in the main drying cylinder is controlled at 125-135℃ to slowly dry the paper web to a finished product moisture content of 6%-8% to prevent fiber embrittlement. During production, key process parameters are recorded hourly, and a "TAD process parameter-product performance" correlation database is constructed.

[0036] Furthermore, in the copying process, the vacuum level of the mesh section is controlled between -0.06 MPa and -0.08 MPa.

[0037] Furthermore, the lamination process in the post-processing step employs a combination of spot bonding and line bonding. Lamination process: For two- or three-layer finished products, a combination of spot bonding and line bonding is used. The spot bonding spacing is 5mm × 5mm, and the line bonding width is 2mm. The lamination pressure is controlled at 0.2-0.3 MPa (controlled in real-time by a pressure sensor) to avoid clogging of the paper's liquid absorption channels caused by traditional full-width bonding.

[0038] Experiment Example 1: Optimization Experiment of the Formulation of a Synergistic System for Wet Strength Agents This experiment aims to determine the optimal addition ratio of PAE (polyamide epichlorohydrin resin) and cationic starch through orthogonal experiments, in order to resolve the contradiction between insufficient wet strength and decreased liquid absorption performance of kitchen paper under low long fiber ratio. The goal is to achieve a longitudinal wet tensile strength of ≥180mN for the base paper while ensuring that the liquid absorption capacity does not decrease.

[0039] Pulp: A mixed pulp prepared with 45% softwood pulp (long fiber, average length 2.8-3.2 mm) and 55% hardwood pulp (short fiber, average length 1.8-2.2 mm), with a freeness controlled at 28-32°SR.

[0040] Chemicals: PAE (industrial grade, solid content 12.5%), cationic starch (industrial grade, degree of substitution 0.03).

[0041] Standard paper sheet forming device (RK-3A type, L&W, Sweden), Shore tapping tester, wet tensile strength tester (compliant with GB / T24328.5-2021), oil absorption tester (modified QB / T 4536-2013), water absorption tester (compliant with GB / T24328.4-2021), high performance liquid chromatograph (for monitoring the actual residual amount of additives).

[0042] The experiment was arranged using a two-factor, four-level orthogonal array (L16(4^5)), with the two core factors being the amount of PAE added (to oven-dry pulp) and the amount of cationic starch added (to oven-dry pulp).

[0043] Factor A (PAE addition): levels were 0.6%, 0.8%, 1.0%, and 1.2%, respectively.

[0044] Factor B (cationic starch addition): levels were 0.05%, 0.08%, 0.10%, and 0.15%. The core evaluation indicators were the longitudinal wet tensile strength (mN) and oil absorption capacity (g / g) of the base paper.

[0045] Slurry preparation: Take a sufficient amount of uniform standard mixed slurry and dilute it to a concentration of 0.5%.

[0046] Additive addition: According to the orthogonal array design, PAE was added to the pulp mixing tank and stirred at 300 rpm for 15 minutes to ensure uniform mixing. Subsequently, before the pulp was pumped to the paper forming machine, the appropriate amount of cationic starch was added and stirred rapidly for 3 minutes.

[0047] Paper forming and drying: Wet paper sheets with a basis weight of 40±2 g / m² were prepared using a standard paper forming machine and then dried under standard conditions (105℃).

[0048] To address the issue of insufficient wet strength with low long fiber ratios, a wet strength agent system combining PAE and cationic starch was adopted. The specific steps were as follows: First, the optimal additive ratio was determined through orthogonal experiments, with PAE added at 0.8%-1.2% of the oven-dry pulp and cationic starch at 0.1%. Under this ratio, the resulting base paper achieved a longitudinal wet tensile strength exceeding 180 mN (according to GB / T24328.5-2021) without any loss of oil absorption capacity. In terms of the addition process, a segmented addition method was adopted: PAE was added in the mixing tank, ensuring thorough mixing with the pulp for at least 15 minutes; cationic starch was added before the headbox to prevent premature addition that could lead to pulp flocculation. The precise and stable addition amount was ensured using an online concentration monitor (checked hourly).

[0049] Performance testing: After drying, the paper sheets were equilibrated for 4 hours under a standard environment of (23±1)℃ and (50±2)% relative humidity. The longitudinal wet tensile strength was tested according to GB / T 24328.5-2021 standard, and the oil absorption capacity was tested according to the modified QB / T4536-2013 method (using refined edible vegetable oil as the test solution). Each experimental condition was repeated 3 times, and the average value was taken.

[0050] The results of the orthogonal experiment showed that both the amount of PAE added (factor A) and the amount of cationic starch added (factor B) had a significant impact on the longitudinal wet tensile strength of the base paper, and there was an interaction between the two. When the amount of PAE added was below 0.8%, the wet tensile strength was difficult to exceed 160 mN; while when the amount of PAE added was above 1.2%, the oil absorption capacity began to decrease significantly (by about 10-15%). The addition of cationic starch showed a synergistic effect; when its addition amount was 0.10%, it could significantly improve the wet strength at a relatively low PAE dosage (0.8%-1.0%).

[0051] Optimal formulation determination: Through range analysis and variance analysis, the optimal combination was determined to be A2B3 or A3B3, i.e., PAE addition of 0.8%-1.0% and cationic starch addition of 0.10%. Under this formulation, the longitudinal wet tensile strength of the base paper was stable between 180-195 mN, and the oil absorption capacity showed no statistically significant decrease compared with the blank control group (no wet strength agent added), fully achieving the experimental objectives.

[0052] Example 2 Secondly, the present invention also provides a washable and environmentally friendly kitchen paper, which is produced by any of the washing and environmentally friendly kitchen paper production processes described in any one of the claims.

[0053] Furthermore, its longitudinal wet tensile strength is not less than 300mN, and it can withstand no less than 4 standard water washing tests.

[0054] Experimental Example 2 To ensure stable and reliable product quality, a testing system covering the entire process of "raw materials - process - finished product" in the production of washable and environmentally friendly kitchen paper products is established.

[0055] Raw material testing: The fiber length (microscopic method), pulp whiteness (ISO whiteness meter test, not less than 88% ISO) and pH value (pH meter test, range 7.0-7.5) of the pulp used in the production process of the test example are tested.

[0056] Process monitoring: The pulping freeness (Shore freeness tester), pulp wet weight (controlled at 3.5-4.0g), and actual amount of wet strength agent added are tested every hour (high performance liquid chromatography).

[0057] Finished product testing: The finished product's tensile strength (GB / T 12914-2018), wet tensile strength (GB / T24328.5-2021), oil absorption capacity (QB / T 4536-2013), and water absorption capacity (GB / T 24328.4-2021) are tested according to national standards.

[0058] In addition, the company has formulated and implemented the enterprise standard "Washable Kitchen Paper" (Q / VD 001-2026), which clearly stipulates the testing methods and performance requirements for the number of times the product can be washed, and the number of washes should not be less than 4.

[0059] Finally, it should be noted that the production process of washable and environmentally friendly kitchen paper disclosed in the embodiments of the present invention is only a preferred embodiment of the present invention and is only used to illustrate the technical solution of the present invention, not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A production process for washable and environmentally friendly kitchen paper, characterized in that, Includes the following steps: Pulp preparation: 45% imported softwood pulp and 55% imported hardwood pulp are mixed; the softwood pulp is lightly beaten, and the beating degree is controlled at 30-35°SR. Fiber grading sieves are used to ensure that the retained fiber length is not less than 2.8 mm. The hardwood pulp is medium-beaten, and the beating degree is controlled at 25-30°SR. The fiber specific surface area is increased to not less than 1.2 m² / g through a grinding process. Wet strength agent addition: Polyamide epichlorohydrin resin and cationic starch are added to the slurry and mixed until homogeneous; the amount of polyamide epichlorohydrin resin added is 0.8%-1.0% of the oven-dry slurry mass; the amount of cationic starch added is 0.1% of the oven-dry slurry mass; the polyamide epichlorohydrin resin is added in the slurry mixing tank and the mixing time with the slurry is not less than 15 minutes; Cationic starch is added before the headbox; Papermaking: The pulp with added wet strength agent is fed to the wire section of the TAD paper machine and dewatered to form a wet paper web; TAD Drying: The wet paper web is sequentially passed through the front drying cylinder and the main drying cylinder of the TAD paper machine for hot air penetration drying. The hot air velocity of the main drying cylinder air hood system is 18-20 m / s. Post-processing: The dried paper web is sequentially calendered, laminated, and slit to obtain the washable and environmentally friendly kitchen paper. The lamination process adopts a combination of spot bonding and line bonding. The spacing between the spot bonds is 5mm×5mm, the width of the line bonds is 2mm, and the lamination pressure is controlled at 0.2-0.3MPa.

2. The production process according to claim 1, characterized in that, In the TAD drying step, the temperature of the pre-drying cylinder is 120-130℃, and the temperature of the main drying cylinder is 130-140℃.

3. The production process according to claim 1, characterized in that, In the copying process, the vacuum level of the mesh section is controlled between -0.06 MPa and -0.08 MPa.

4. A washable and environmentally friendly kitchen paper towel, characterized in that, The kitchen paper is produced by the production process described in claim 1; the kitchen paper is a laminated paper formed by combining two layers of paper webs through a combination of dot bonding and line bonding, wherein the dot bonding spacing is 5mm×5mm and the line bonding width is 2mm. Its longitudinal wet tensile strength is not less than 300mN and it can withstand no less than 4 standard water washing tests; the water temperature of the standard water washing test is 25-30℃, the detergent concentration is 0.5%, and the stirring speed is 100r / min.

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