Enhanced protection method for edge section of full-paper-based container

Abstract

The invention discloses a reinforced protection method for an edge section of a full-paper-based container, which belongs to the technical field of paper-based container treatment, and comprises the following steps: step 1, end surface pretreatment: carrying out chip removal treatment on the cut end surface of a paper tube, and keeping a loose state of fibers; step 2, local impregnation and permeation: vertically and downwards immersing the end surface of the paper tube into the prepared solution, fixing the immersion depth to be 0.8 mm, keeping the immersion depth for 5 seconds, and enabling the paper tube to naturally permeate upwards along a gap of a paper layer by utilizing the low viscosity characteristic of the liquid; and 3, gradient curing is conducted, specifically, the treated paper tube is placed in circulating hot air at the temperature of 55 DEG C to be dried for 15 minutes. Different from a traditional method for coating the whole pipe body or compounding a plastic inner container, only the weakest cutting end face is subjected to precise treatment, the equivalent and even better protection effect is achieved, meanwhile, the use amount of chemicals is greatly reduced, the production cost is reduced, and the original advantages of air permeability of the wall body of the paper pipe and the like are kept.

Description

Technical Field

[0001] This invention belongs to the field of paper-based container processing technology, and particularly relates to a method for strengthening and protecting the edge cut surfaces of an all-paper-based container. Background Technology

[0002] The application of paper-based packaging in the cosmetics industry is undergoing a substantial leap from "outer packaging" to "direct contact containers".

[0003] Initial stage (physical shielding): In the early stages, the paper tubes were only used as outer boxes and did not directly contact the paste. Interface protection was almost zero, relying solely on the density of the paper fibers.

[0004] Intermediate stage (localized precision protection and bio-based barrier): Instead of relying on an overall plastic barrier, this stage focuses on molecular-level penetration and reinforcement of the paper's most vulnerable **"cut surfaces" and "friction interfaces." Bio-based materials (such as modified cellulose and water-based coatings) alter the energy state of the fiber surface, giving the paper similar oil, water, and friction resistance to plastics. The existing solution has the following drawbacks: Capillary action: After the paper tubes are slit, the exposed fiber ends have a strong capillary effect. Oils or water in cosmetics can quickly penetrate into the paper layers through the cuts.

[0005] Structural damage: Once the paste seeps in, it will cause the adhesive between the paper layers to fail (seamlessness), the paper fibers to swell and soften (breakage), and ultimately the entire packaging will collapse.

[0006] Dynamic wear failure: When sliding components (such as pushers) frequently rub against the cut surface, the untreated cut surface is prone to fuzzing and delamination, resulting in paper dust contamination of the paste. To address this, we propose a method for reinforcing and protecting the edge cut surfaces of all-paper-based containers. Summary of the Invention

[0007] To address the aforementioned issues, this invention proposes a method for reinforcing and protecting the edge cut surfaces of all-paper-based containers. This method overcomes the shortcomings of existing technologies, such as the failure of interlayer adhesives and the expansion and softening of paper fibers after the paste seeps in, ultimately leading to the collapse of the entire packaging.

[0008] This invention is achieved through the following technical solution: This invention proposes a method for reinforcing and protecting the edge cut surface of an all-paper-based container, comprising the following steps: Step 1: End face pretreatment. The paper tube cutting end face is treated to remove chips and keep the fibers loose. Step 2: Local immersion and penetration. Immerse the end face of the paper tube vertically downward into the prepared solution, with a fixed immersion depth of 0.8 mm and a holding time of 5 seconds. Utilize the low viscosity of the liquid to allow it to naturally penetrate upward along the gaps between the paper layers. Step 3: Gradient curing. The treated paper tube is placed in a 55°C circulating hot air dryer for 15 minutes. During this process, the nanoparticles in the solution migrate with the moisture and form a high-density "hardening plug" in the 0.2mm area near the cut surface.

[0009] Furthermore, the paper tube, after being cut, has a three-layer structure with a wall thickness of 1.5 mm and an inner diameter of 20 mm.

[0010] Furthermore, the solution is a modified acrylic copolymer emulsion with a solid content of 20%, a viscosity of 25 mPa·s, and an average particle size of 0.1 μm.

[0011] Furthermore, in step one, the cut end face of the paper tube is heated to 50°C by infrared heating to form open fiber micropores.

[0012] Furthermore, following step one, an ultraviolet or ozone surface cleaning and activation step is included to remove trace organic contaminants from the cut surface and improve the fiber surface energy, thereby enhancing solution penetration and adhesion.

[0013] Furthermore, after step three, an in-situ photocuring or hot-pressing flattening step is also included to form a denser and smoother barrier layer on the cut surface, with its surface roughness Ra controlled below 0.5 μm.

[0014] Furthermore, the method is particularly suitable for processing rotationally formed or wound paper-based containers with an inner diameter between 10 mm and 50 mm and a wall thickness between 0.8 mm and 3.0 mm.

[0015] Furthermore, the solution comprises the following components in mass fractions: Modified acrylic copolymer emulsion: 40% - 60%; Nanocellulose dispersion: 20% - 40%; Bio-based wax microemulsions: 5% - 15%; Water: Balance; Furthermore, the dynamic viscosity of the solution at 25°C was ultimately adjusted to 15 mPa·s - 40 mPa·s.

[0016] Furthermore, in step two, by controlling the surface tension of the solution to be 25-35 mN / m and the preheating temperature of the paper tube end face to be between 45°C and 60°C, the capillary permeation rate and final morphology of the solution in the gap between the paper layers are jointly regulated, so that the outline of the permeation front of the formed "hardened plug" is serrated or feather-shaped, in order to maximize the mechanical interlocking area with the paper fibers.

[0017] Furthermore, the method is also applicable to strengthening and protecting the cut end face of paper-based containers with multi-layer composite structures or surfaces that have been printed or aluminum-plated; before processing, the end face of the composite layer or surface treatment layer needs to be plasma-treated to remove the weak boundary layer at the interface and improve the affinity of each layer of material to the solution.

[0018] The method for reinforcing and protecting the edge cut surface of an all-paper-based container proposed in this invention can bring the following beneficial effects: 1. Through precise local deep penetration, a "chemical anchor" is formed in the fiber gaps, which fundamentally blocks the path of oil and water diffusion inward along the capillary of the cut surface, and completely solves the problems of interlayer delamination, fiber swelling and softening and overall structural collapse caused by oil seepage in traditional paper tubes. 2. After the paper tube cut surface treated by this method comes into contact with a high-oil cosmetic paste (such as lipstick or perfume) and is stored for 12 months, the interlayer peel strength of its edge area decreases by no more than 5%, and there are no visible penetration marks. 3. The cured "hardened plug" significantly improves the hardness and scratch resistance of the paper base surface, enabling it to withstand long-term reciprocating friction of sliding components (such as pushers and pistons) without fuzzing or delamination. 4. It effectively seals the loose fibers on the cut end face, ensuring that no paper scraps or fiber fragments fall off during use, avoiding cosmetic contamination caused by this, and meeting the stringent purity requirements of the high-end market. 5. By using water-based or bio-based materials such as modified acrylic acid, nanocellulose, and bio-wax, the treated paper-based containers can be completely pulped and recycled after disposal, without affecting the paper recycling cycle, thus realizing a green closed loop throughout the entire life cycle from raw materials to waste. In summary, this solution features a simple structure and novel design. Unlike traditional methods that coat or composite plastic liner on the entire tube, this invention precisely treats only the weakest cut end face. While achieving the same or even better protective effect, it greatly reduces the amount of chemicals used, lowers production costs, and maintains the original advantages of the paper tube wall, such as its breathability. Attached Figure Description

[0019] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0020] In the attached diagram: Figure 1 This is a schematic diagram of the process structure of the present invention. Detailed Implementation

[0021] This invention proposes a method for reinforcing and protecting the edge cut surface of an all-paper-based container, comprising the following steps: Step 1: End face pretreatment. The paper tube cutting end face is treated to remove chips and keep the fibers loose. Step 2: Local immersion and penetration. Immerse the end face of the paper tube vertically downward into the prepared solution, with a fixed immersion depth of 0.8 mm and a holding time of 5 seconds. Utilize the low viscosity of the liquid to allow it to naturally penetrate upward along the gaps between the paper layers. Step 3: Gradient curing. The treated paper tube is placed in a 55°C circulating hot air dryer for 15 minutes. During this process, the nanoparticles in the solution migrate with the moisture and form a high-density "hardening plug" in the 0.2mm area near the cut surface.

[0022] In this embodiment, the paper tube is cut into three layers, with a wall thickness of 1.5 mm and an inner diameter of 20 mm.

[0023] In this embodiment, the solution is a modified acrylic copolymer emulsion with a solid content of 20%, a viscosity of 25 mPa·s, and an average particle size of 0.1 μm.

[0024] In this embodiment, in step one, the cut end face of the paper tube is heated to 50°C by infrared heating to form open fiber micropores.

[0025] In this embodiment, after step one, there is also a UV or ozone surface cleaning and activation step to remove trace organic pollutants from the cut surface and improve the fiber surface energy, thereby enhancing solution penetration and adhesion.

[0026] In this embodiment, after step three, there is also an in-situ photocuring or hot-pressing flattening step, which makes the cut surface layer form a denser and smoother barrier layer, with its surface roughness Ra controlled below 0.5μm.

[0027] In this embodiment, the method is particularly suitable for processing paper-based containers formed by rotation or winding with an inner diameter between 10 mm and 50 mm and a wall thickness between 0.8 mm and 3.0 mm.

[0028] The solution consists of the following components by mass fraction: Modified acrylic copolymer emulsion: 40% - 60%; Nanocellulose dispersion: 20% - 40%; Bio-based wax microemulsions: 5% - 15%; Water: Balance; The dynamic viscosity of the solution at 25°C was eventually adjusted to 15 mPa·s - 40 mPa·s.

[0029] In this embodiment, in step two, by controlling the surface tension of the solution to be 25-35 mN / m and the preheating temperature of the paper tube end face to be between 45°C and 60°C, the capillary permeation rate and final morphology of the solution in the gap between the paper layers are jointly regulated, so that the outline of the permeation front of the formed "hardened plug" is serrated or feather-shaped, so as to maximize the mechanical interlocking area with the paper fibers.

[0030] In this embodiment, the method is also applicable to strengthening the protection of the cut end face of paper-based containers with multi-layer composite structures or with printed or aluminum-plated surfaces; before processing, the end face of the composite layer or surface treatment layer needs to be plasma-treated to remove the weak boundary layer at the interface and improve the affinity of each layer of material to the solution.

[0031] Example 1: Enhanced protection against highly oily ointments Objective: To provide reinforced protection for paper tubes containing lipsticks with high plant oil content.

[0032] Paper tube specifications: Three-layer white cardboard wound tube, wall thickness 1.5mm, inner diameter 16mm.

[0033] Strengthening solution: Take the formula in claim 5 (50% modified acrylic emulsion, 30% nanocellulose dispersion, 10% carnauba wax microemulsion, and 10% water) according to the mass ratio, stir evenly and adjust the viscosity to 25 mPa·s.

[0034] Process steps: Pretreatment: Place the end face of the paper tube under 60°C infrared heat for 30 seconds.

[0035] Immersion: Immerse vertically into the solution to a depth of 1.0 mm and hold for 5 seconds.

[0036] Curing: Place in a 60°C hot air bath and allow to dry gradually for 20 minutes.

[0037] Results: The static contact angle of the treated cut surface with olive oil reached 115°. After accelerated aging test (40°C, 75% humidity, 90 days of storage), there were no signs of grease penetration, and no visible wear was observed after 1000 rubs on the cut surface.

[0038] Example 2: Moisture-proof and friction-resistant protection for water-based cream containers Objective: To improve the moisture resistance of the end face of paper cans containing water-based creams and their abrasion resistance under repeated twisting and turning with plastic caps.

[0039] Paper can specifications: Molded paper can, wall thickness 2.0mm, end face is flat cut.

[0040] Enhanced solution: Focusing on hydrophobicity and lubrication. The formula was adjusted to: 60% modified acrylic emulsion, 15% fluorocarbon modified hydrophobic emulsion, 15% polyethylene wax microemulsion, and 10% water, with the viscosity adjusted to 18 mPa·s.

[0041] Process steps: Pretreatment: The surface is first activated by ozone treatment for 10 seconds.

[0042] Impregnation: The end face is treated with a precise spraying method to control the thickness of the wet film.

[0043] Curing: First, use hot air at 50°C to dry for 10 minutes, then roll at 80°C for 10 seconds to make the surface smooth.

[0044] Results: After treatment, the water contact angle of the cut surface reached 130°, and the water absorption decreased by 90%. After 500 simulated cap screwing tests, there was no obvious wear on the cut surface, and the screwing torque remained stable.

[0045] Example 3: High-speed processing solution adapted to automated production lines Objective: To adapt to high-speed production lines and shorten process time.

[0046] Paper tube specifications: Roll paper tubes in various diameters.

[0047] Strengthening solution: Utilizes a UV curing system. The formula is as follows: 70% UV-curable waterborne polyurethane acrylate emulsion, 5% nano-silica (hardening agent), 3% photoinitiator, 1% leveling agent, and 21% water.

[0048] Process steps: Pretreatment: Online plasma cleaning.

[0049] Coating: The solution is transferred to the end face of a rotating paper tube using precision metering rollers.

[0050] Curing: Surface drying and deep curing are achieved immediately by irradiating with a high-intensity UV LED lamp for 3 seconds.

[0051] Results: The entire processing cycle is less than 10 seconds, perfectly matching high-speed production lines. The cured coating has high hardness, good wear resistance, and extremely low VOC emissions.

[0052] The performance test data is as follows:

[0053] The test comparison is as follows:

[0054] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0055] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

[0056] Of course, the present invention may have many other embodiments. Based on this embodiment, other embodiments obtained by those skilled in the art without any creative effort are all within the scope of protection of the present invention.

Claims

1. A method for reinforcing and protecting the edge cut surface of an all-paper-based container, characterized in that, Includes the following steps: Step 1: End face pretreatment. The paper tube cutting end face is treated to remove chips and keep the fibers loose. Step 2: Local immersion and penetration. Immerse the end face of the paper tube vertically downward into the prepared solution, with a fixed immersion depth of 0.8 mm and a holding time of 5 seconds. Utilize the low viscosity of the liquid to allow it to naturally penetrate upward along the gaps between the paper layers. Step 3: Gradient curing. The treated paper tube is placed in a 55°C circulating hot air dryer for 15 minutes. During this process, the nanoparticles in the solution migrate with the moisture and form a high-density "hardened plug" in the 0.2mm area near the cut surface.

2. The method for reinforcing and protecting the edge cut surface of an all-paper-based container according to claim 1, characterized in that, The paper tube is cut into three layers, with a wall thickness of 1.5 mm and an inner diameter of 20 mm.

3. The method for reinforcing and protecting the edge cut surface of an all-paper-based container according to claim 1, characterized in that, The solution is a modified acrylic copolymer emulsion with a solid content of 20%, a viscosity of 25 mPa·s, and an average particle size of 0.1 μm.

4. The method for reinforcing and protecting the edge cut surface of an all-paper-based container according to claim 1, characterized in that, In step one, the cut end face of the paper tube is heated to 50°C by infrared heating to form open fiber micropores.

5. The method for reinforcing and protecting the edge cut surface of an all-paper-based container according to claim 1, characterized in that, Following step one, a UV or ozone surface cleaning and activation step is also included to remove trace organic contaminants from the cut surface and improve the fiber surface energy, thereby enhancing solution penetration and adhesion.

6. The method for reinforcing and protecting the edge cut surface of an all-paper-based container according to claim 1, characterized in that, Following step three, an in-situ photocuring or hot-pressing flattening step is also included to form a denser and smoother barrier layer on the cut surface, with its surface roughness Ra controlled below 0.5 μm.

7. The method for reinforcing and protecting the edge cut surface of an all-paper-based container according to claim 1, characterized in that, The method is particularly suitable for processing rotationally formed or wound paper-based containers with an inner diameter between 10 mm and 50 mm and a wall thickness between 0.8 mm and 3.0 mm.

8. A method for reinforcing and protecting the edge cut surface of an all-paper-based container according to claim 1, characterized in that, The solution consists of the following components by mass fraction: Modified acrylic copolymer emulsion: 40%-60%; Nanocellulose dispersion: 20%-40%; Bio-based wax microemulsions: 5%-15%; Water: Balance; Furthermore, the dynamic viscosity of the solution at 25°C was ultimately adjusted to 15 mPa·s - 40 mPa·s.

9. A method for reinforcing and protecting the edge cut surface of an all-paper-based container according to claim 1, characterized in that, In step two, by controlling the surface tension of the solution to 25-35 mN / m and the preheating temperature of the paper tube end face to between 45°C and 60°C, the capillary permeation rate and final morphology of the solution in the gap between the paper layers are jointly regulated, so that the outline of the permeation front of the formed "hardened plug" is serrated or feather-shaped, in order to maximize the mechanical interlocking area with the paper fibers.

10. A method for reinforcing and protecting the edge cut surface of an all-paper-based container according to claim 1, characterized in that, The method is also applicable to strengthening the protection of the cut end face of paper-based containers with multi-layer composite structures or with printed or aluminum-plated surfaces; before treatment, the end face of the composite layer or surface treatment layer needs to be plasma-treated to remove the weak boundary layer at the interface and improve the affinity of each layer of material to the solution.

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